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  11 <div class="doc_title">
  12   Getting Started with the LLVM System
  13 </div>
  14
  15 <ul>
  16   <li><a href="#overview">Overview</a>
  17   <li><a href="#quickstart">Getting Started Quickly (A Summary)</a>
  18   <li><a href="#requirements">Requirements</a>
  19     <ol>
  20       <li><a href="#hardware">Hardware</a></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="#llvmtest"><tt>llvm-test</tt></a></li>
  48       <li><a href="#tools"><tt>llvm/tools</tt></a></li>
  49       <li><a href="#utils"><tt>llvm/utils</tt></a></li>
  50       <li><a href="#win32"><tt>llvm/win32</tt></a></li>
  51     </ol></li>
  52
  53   <li><a href="#tutorial">An Example Using the LLVM Tool Chain</a>
  54       <ol>
  55          <li><a href="#tutorial4">Example with llvm-gcc4</a></li>
  56       </ol>
  57   <li><a href="#problems">Common Problems</a>
  58   <li><a href="#links">Links</a>
  59 </ul>
  60
  61 <div class="doc_author">
  62   <p>Written by:
  63     <a href="mailto:criswell@uiuc.edu">John Criswell</a>,
  64     <a href="mailto:sabre@nondot.org">Chris Lattner</a>,
  65     <a href="http://misha.brukman.net">Misha Brukman</a>,
  66     <a href="http://www.cs.uiuc.edu/~vadve">Vikram Adve</a>, and
  67     <a href="mailto:gshi1@uiuc.edu">Guochun Shi</a>.
  68   </p>
  69 </div>
  70
  71
  72 <!-- *********************************************************************** -->
  73 <div class="doc_section">
  74   <a name="overview"><b>Overview</b></a>
  75 </div>
  76 <!-- *********************************************************************** -->
  77
  78 <div class="doc_text">
  79
  80 <p>Welcome to LLVM! In order to get started, you first need to know some
  81 basic information.</p>
  82
  83 <p>First, LLVM comes in two pieces. The first piece is the LLVM suite. This
  84 contains all of the tools, libraries, and header files needed to use the low
  85 level virtual machine.  It contains an assembler, disassembler, bitcode
  86 analyzer and bitcode optimizer.  It also contains a test suite that can be
  87 used to test the LLVM tools and the GCC front end.</p>
  88
  89 <p>The second piece is the GCC front end.  This component provides a version of
  90 GCC that compiles C and C++ code into LLVM bitcode.  Currently, the GCC front
  91 end uses the GCC parser to convert code to LLVM.  Once
  92 compiled into LLVM bitcode, a program can be manipulated with the LLVM tools
  93 from the LLVM suite.</p>
  94
  95 <p>
  96 There is a third, optional piece called llvm-test.  It is a suite of programs
  97 with a testing harness that can be used to further test LLVM's functionality
  98 and performance.
  99 </p>
 100
 101 </div>
 102
 103 <!-- *********************************************************************** -->
 104 <div class="doc_section">
 105   <a name="quickstart"><b>Getting Started Quickly (A Summary)</b></a>
 106 </div>
 107 <!-- *********************************************************************** -->
 108
 109 <div class="doc_text">
 110
 111 <p>Here's the short story for getting up and running quickly with LLVM:</p>
 112
 113 <ol>
 114   <li>Read the documentation.</li>
 115   <li>Read the documentation.</li>
 116   <li>Remember that you were warned twice about reading the documentation.</li>
 117   <li>Install the 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     </ol></li>
 146
 147   </ul></li>
 148
 149
 150   <li>Configure the LLVM Build Environment
 151   <ol>
 152     <li><tt>cd <i>where-you-want-to-build-llvm</i></tt></li>
 153     <li><tt><i>/path/to/llvm/</i>configure [options]</tt><br>
 154     Some common options:
 155
 156       <ul>
 157         <li><tt>--prefix=<i>directory</i></tt>
 158         <p>Specify for <i>directory</i> the full pathname of where you
 159         want the LLVM tools and libraries to be installed (default
 160         <tt>/usr/local</tt>).</p></li>
 161         <li><tt>--with-llvmgccdir=<i>directory</i></tt>
 162         <p>Optionally, specify for <i>directory</i> the full pathname of the
 163         C/C++ front end installation to use with this LLVM configuration. If
 164         not specified, the PATH will be searched.  This is only needed if you
 165         want to run the testsuite or do some special kinds of LLVM builds.</p></li>
 166         <li><tt>--enable-spec2000=<i>directory</i></tt>
 167             <p>Enable the SPEC2000 benchmarks for testing.  The SPEC2000
 168             benchmarks should be available in
 169             <tt><i>directory</i></tt>.</p></li>
 170       </ul>
 171   </ol></li>
 172
 173   <li>Build the LLVM Suite:
 174   <ol>
 175       <li><tt>gmake -k |&amp; tee gnumake.out
 176       &nbsp;&nbsp;&nbsp;# this is csh or tcsh syntax</tt></li>
 177       <li>If you get an "internal compiler error (ICE)" or test failures, see
 178           <a href="#brokengcc">below</a>.</li>
 179   </ol>
 180
 181 </ol>
 182
 183 <p>Consult the <a href="#starting">Getting Started with LLVM</a> section for
 184 detailed information on configuring and compiling LLVM.  See <a
 185 href="#environment">Setting Up Your Environment</a> for tips that simplify
 186 working with the GCC front end and LLVM tools.  Go to <a href="#layout">Program
 187 Layout</a> to learn about the layout of the source code tree.</p>
 188
 189 </div>
 190
 191 <!-- *********************************************************************** -->
 192 <div class="doc_section">
 193   <a name="requirements"><b>Requirements</b></a>
 194 </div>
 195 <!-- *********************************************************************** -->
 196
 197 <div class="doc_text">
 198
 199 <p>Before you begin to use the LLVM system, review the requirements given below.
 200 This may save you some trouble by knowing ahead of time what hardware and
 201 software you will need.</p>
 202
 203 </div>
 204
 205 <!-- ======================================================================= -->
 206 <div class="doc_subsection">
 207   <a name="hardware"><b>Hardware</b></a>
 208 </div>
 209
 210 <div class="doc_text">
 211
 212 <p>LLVM is known to work on the following platforms:</p>
 213
 214 <table cellpadding="3" summary="Known LLVM platforms">
 215 <tr>
 216   <th>OS</th>
 217   <th>Arch</th>
 218   <th>Compilers</th>
 219 </tr>
 220 <tr>
 221   <td>AuroraUX</td>
 222   <td>x86<sup><a href="#pf_1">1</a></sup></td>
 223   <td>GCC</td>
 224 </tr>
 225 <tr>
 226   <td>Linux</td>
 227   <td>x86<sup><a href="#pf_1">1</a></sup></td>
 228   <td>GCC</td>
 229 </tr>
 230 <tr>
 231   <td>Linux</td>
 232   <td>amd64</td>
 233   <td>GCC</td>
 234 </tr>
 235 <tr>
 236   <td>Solaris</td>
 237   <td>V9 (Ultrasparc)</td>
 238   <td>GCC</td>
 239 </tr>
 240 <tr>
 241   <td>FreeBSD</td>
 242   <td>x86<sup><a href="#pf_1">1</a></sup></td>
 243   <td>GCC</td>
 244 </tr>
 245 <tr>
 246   <td>MacOS X<sup><a href="#pf_2">2</a></sup></td>
 247   <td>PowerPC</td>
 248   <td>GCC</td>
 249 </tr>
 250 <tr>
 251   <td>MacOS X<sup><a href="#pf_2">2</a>,<a href="#pf_9">9</a></sup></td>
 252   <td>x86</td>
 253   <td>GCC</td>
 254 </tr>
 255 <tr>
 256   <td>Cygwin/Win32</td>
 257   <td>x86<sup><a href="#pf_1">1</a>,<a href="#pf_8">8</a>,
 258      <a href="#pf_11">11</a></sup></td>
 259   <td>GCC 3.4.X, binutils 2.20</td>
 260 </tr>
 261 <tr>
 262   <td>MinGW/Win32</td>
 263   <td>x86<sup><a href="#pf_1">1</a>,<a href="#pf_6">6</a>,
 264      <a href="#pf_8">8</a>, <a href="#pf_10">10</a></sup></td>
 265   <td>GCC 3.4.X, binutils 2.20</td>
 266 </tr>
 267 </table>
 268
 269 <p>LLVM has partial support for the following platforms:</p>
 270
 271 <table summary="LLVM partial platform support">
 272 <tr>
 273   <th>OS</th>
 274   <th>Arch</th>
 275   <th>Compilers</th>
 276 </tr>
 277 <tr>
 278   <td>Windows</td>
 279   <td>x86<sup><a href="#pf_1">1</a></sup></td>
 280   <td>Visual Studio 2005 SP1 or higher<sup><a href="#pf_4">4</a>,<a href="#pf_5">5</a></sup></td>
 281 <tr>
 282   <td>AIX<sup><a href="#pf_3">3</a>,<a href="#pf_4">4</a></sup></td>
 283   <td>PowerPC</td>
 284   <td>GCC</td>
 285 </tr>
 286 <tr>
 287   <td>Linux<sup><a href="#pf_3">3</a>,<a href="#pf_5">5</a></sup></td>
 288   <td>PowerPC</td>
 289   <td>GCC</td>
 290 </tr>
 291
 292 <tr>
 293   <td>Linux<sup><a href="#pf_7">7</a></sup></td>
 294   <td>Alpha</td>
 295   <td>GCC</td>
 296 </tr>
 297 <tr>
 298   <td>Linux<sup><a href="#pf_7">7</a></sup></td>
 299   <td>Itanium (IA-64)</td>
 300   <td>GCC</td>
 301 </tr>
 302 <tr>
 303   <td>HP-UX<sup><a href="#pf_7">7</a></sup></td>
 304   <td>Itanium (IA-64)</td>
 305   <td>HP aCC</td>
 306 </tr>
 307 </table>
 308
 309 <p><b>Notes:</b></p>
 310
 311 <div class="doc_notes">
 312 <ol>
 313 <li><a name="pf_1">Code generation supported for Pentium processors and
 314 up</a></li>
 315 <li><a name="pf_2">Code generation supported for 32-bit ABI only</a></li>
 316 <li><a name="pf_3">No native code generation</a></li>
 317 <li><a name="pf_4">Build is not complete: one or more tools do not link or function</a></li>
 318 <li><a name="pf_5">The GCC-based C/C++ frontend does not build</a></li>
 319 <li><a name="pf_6">The port is done using the MSYS shell.</a></li>
 320 <li><a name="pf_7">Native code generation exists but is not complete.</a></li>
 321 <li><a name="pf_8">Binutils 2.20 or later is required to build the assembler
 322     generated by LLVM properly.</a></li>
 323 <li><a name="pf_9">XCode 2.5 and gcc 4.0.1</a> (Apple Build 5370) will trip
 324     internal LLVM assert messages when compiled for Release at optimization
 325     levels greater than 0 (i.e., <i>"-O1"</i> and higher).
 326     Add <i>OPTIMIZE_OPTION="-O0"</i> to the build command line
 327     if compiling for LLVM Release or bootstrapping the LLVM toolchain.</li>
 328 <li><a name="pf_10">For MSYS/MinGW on Windows, be sure to install the MSYS
 329     version of the perl package, and be sure it appears in your path
 330     before any Windows-based versions such as Strawberry Perl and
 331     ActivePerl, as these have Windows-specifics that will cause the
 332     build to fail.</a></li>
 333 <li><a name="pf_11">In general, LLVM modules requiring dynamic linking can
 334     not be built on Windows. However, you can build LLVM tools using
 335     <i>"make tools-only"</i>.</li>
 336 </ol>
 337 </div>
 338
 339 <p>Note that you will need about 1-3 GB of space for a full LLVM build in Debug
 340 mode, depending on the system (it is so large because of all the debugging
 341 information and the fact that the libraries are statically linked into multiple
 342 tools).  If you do not need many of the tools and you are space-conscious, you
 343 can pass <tt>ONLY_TOOLS="tools you need"</tt> to make.  The Release build
 344 requires considerably less space.</p>
 345
 346 <p>The LLVM suite <i>may</i> compile on other platforms, but it is not
 347 guaranteed to do so.  If compilation is successful, the LLVM utilities should be
 348 able to assemble, disassemble, analyze, and optimize LLVM bitcode.  Code
 349 generation should work as well, although the generated native code may not work
 350 on your platform.</p>
 351
 352 <p>The GCC front end is not very portable at the moment.  If you want to get it
 353 to work on another platform, you can download a copy of the source and <a
 354 href="GCCFEBuildInstrs.html">try to compile it</a> on your platform.</p>
 355
 356 </div>
 357
 358 <!-- ======================================================================= -->
 359 <div class="doc_subsection"><a name="software"><b>Software</b></a></div>
 360 <div class="doc_text">
 361   <p>Compiling LLVM requires that you have several software packages
 362   installed. The table below lists those required packages. The Package column
 363   is the usual name for the software package that LLVM depends on. The Version
 364   column provides "known to work" versions of the package. The Notes column
 365   describes how LLVM uses the package and provides other details.</p>
 366   <table summary="Packages required to compile LLVM">
 367     <tr><th>Package</th><th>Version</th><th>Notes</th></tr>
 368
 369     <tr>
 370       <td><a href="http://savannah.gnu.org/projects/make">GNU Make</a></td>
 371       <td>3.79, 3.79.1</td>
 372       <td>Makefile/build processor</td>
 373     </tr>
 374
 375     <tr>
 376       <td><a href="http://gcc.gnu.org">GCC</a></td>
 377       <td>3.4.2</td>
 378       <td>C/C++ compiler<sup><a href="#sf1">1</a></sup></td>
 379     </tr>
 380
 381     <tr>
 382       <td><a href="http://www.gnu.org/software/texinfo">TeXinfo</a></td>
 383       <td>4.5</td>
 384       <td>For building the CFE</td>
 385     </tr>
 386
 387     <tr>
 388       <td><a href="http://subversion.tigris.org/project_packages.html">SVN</a></td>
 389       <td>&ge;1.3</td>
 390       <td>Subversion access to LLVM<sup><a href="#sf2">2</a></sup></td>
 391     </tr>
 392
 393     <tr>
 394       <td><a href="http://savannah.gnu.org/projects/dejagnu">DejaGnu</a></td>
 395       <td>1.4.2</td>
 396       <td>Automated test suite<sup><a href="#sf3">3</a></sup></td>
 397     </tr>
 398
 399     <tr>
 400       <td><a href="http://www.tcl.tk/software/tcltk/">tcl</a></td>
 401       <td>8.3, 8.4</td>
 402       <td>Automated test suite<sup><a href="#sf3">3</a></sup></td>
 403     </tr>
 404
 405     <tr>
 406       <td><a href="http://expect.nist.gov/">expect</a></td>
 407       <td>5.38.0</td>
 408       <td>Automated test suite<sup><a href="#sf3">3</a></sup></td>
 409     </tr>
 410
 411     <tr>
 412       <td><a href="http://www.perl.com/download.csp">perl</a></td>
 413       <td>&ge;5.6.0</td>
 414       <td>Nightly tester, utilities</td>
 415     </tr>
 416
 417     <tr>
 418       <td><a href="http://savannah.gnu.org/projects/m4">GNU M4</a>
 419       <td>1.4</td>
 420       <td>Macro processor for configuration<sup><a href="#sf4">4</a></sup></td>
 421     </tr>
 422
 423     <tr>
 424       <td><a href="http://www.gnu.org/software/autoconf">GNU Autoconf</a></td>
 425       <td>2.60</td>
 426       <td>Configuration script builder<sup><a href="#sf4">4</a></sup></td>
 427     </tr>
 428
 429     <tr>
 430       <td><a href="http://www.gnu.org/software/automake">GNU Automake</a></td>
 431       <td>1.9.6</td>
 432       <td>aclocal macro generator<sup><a href="#sf4">4</a></sup></td>
 433     </tr>
 434
 435     <tr>
 436       <td><a href="http://savannah.gnu.org/projects/libtool">libtool</a></td>
 437       <td>1.5.22</td>
 438       <td>Shared library manager<sup><a href="#sf4">4</a></sup></td>
 439     </tr>
 440
 441   </table>
 442
 443   <p><b>Notes:</b></p>
 444   <div class="doc_notes">
 445   <ol>
 446     <li><a name="sf1">Only the C and C++ languages are needed so there's no
 447       need to build the other languages for LLVM's purposes.</a> See
 448       <a href="#brokengcc">below</a> for specific version info.</li>
 449     <li><a name="sf2">You only need Subversion if you intend to build from the
 450       latest LLVM sources. If you're working from a release distribution, you
 451       don't need Subversion.</a></li>
 452     <li><a name="sf3">Only needed if you want to run the automated test
 453       suite in the <tt>llvm/test</tt> directory.</a></li>
 454     <li><a name="sf4">If you want to make changes to the configure scripts,
 455       you will need GNU autoconf (2.60), and consequently, GNU M4 (version 1.4
 456       or higher). You will also need automake (1.9.6). We only use aclocal
 457       from that package.</a></li>
 458   </ol>
 459   </div>
 460
 461   <p>Additionally, your compilation host is expected to have the usual
 462   plethora of Unix utilities. Specifically:</p>
 463   <ul>
 464     <li><b>ar</b> - archive library builder</li>
 465     <li><b>bzip2*</b> - bzip2 command for distribution generation</li>
 466     <li><b>bunzip2*</b> - bunzip2 command for distribution checking</li>
 467     <li><b>chmod</b> - change permissions on a file</li>
 468     <li><b>cat</b> - output concatenation utility</li>
 469     <li><b>cp</b> - copy files</li>
 470     <li><b>date</b> - print the current date/time </li>
 471     <li><b>echo</b> - print to standard output</li>
 472     <li><b>egrep</b> - extended regular expression search utility</li>
 473     <li><b>find</b> - find files/dirs in a file system</li>
 474     <li><b>grep</b> - regular expression search utility</li>
 475     <li><b>gzip*</b> - gzip command for distribution generation</li>
 476     <li><b>gunzip*</b> - gunzip command for distribution checking</li>
 477     <li><b>install</b> - install directories/files </li>
 478     <li><b>mkdir</b> - create a directory</li>
 479     <li><b>mv</b> - move (rename) files</li>
 480     <li><b>ranlib</b> - symbol table builder for archive libraries</li>
 481     <li><b>rm</b> - remove (delete) files and directories</li>
 482     <li><b>sed</b> - stream editor for transforming output</li>
 483     <li><b>sh</b> - Bourne shell for make build scripts</li>
 484     <li><b>tar</b> - tape archive for distribution generation</li>
 485     <li><b>test</b> - test things in file system</li>
 486     <li><b>unzip*</b> - unzip command for distribution checking</li>
 487     <li><b>zip*</b> - zip command for distribution generation</li>
 488   </ul>
 489 </div>
 490
 491 <!-- ======================================================================= -->
 492 <div class="doc_subsection">
 493   <a name="brokengcc">Broken versions of GCC and other tools</a>
 494 </div>
 495
 496 <div class="doc_text">
 497
 498 <p>LLVM is very demanding of the host C++ compiler, and as such tends to expose
 499 bugs in the compiler.  In particular, several versions of GCC crash when trying
 500 to compile LLVM.  We routinely use GCC 3.3.3, 3.4.0, and Apple 4.0.1
 501 successfully with them (however, see important notes below).  Other versions
 502 of GCC will probably work as well.  GCC versions listed
 503 here are known to not work.  If you are using one of these versions, please try
 504 to upgrade your GCC to something more recent.  If you run into a problem with a
 505 version of GCC not listed here, please <a href="mailto:llvmdev@cs.uiuc.edu">let
 506 us know</a>.  Please use the "<tt>gcc -v</tt>" command to find out which version
 507 of GCC you are using.
 508 </p>
 509
 510 <p><b>GCC versions prior to 3.0</b>: GCC 2.96.x and before had several
 511 problems in the STL that effectively prevent it from compiling LLVM.
 512 </p>
 513
 514 <p><b>GCC 3.2.2 and 3.2.3</b>: These versions of GCC fails to compile LLVM with
 515 a bogus template error.  This was fixed in later GCCs.</p>
 516
 517 <p><b>GCC 3.3.2</b>: This version of GCC suffered from a <a
 518 href="http://gcc.gnu.org/PR13392">serious bug</a> which causes it to crash in
 519 the "<tt>convert_from_eh_region_ranges_1</tt>" GCC function.</p>
 520
 521 <p><b>Cygwin GCC 3.3.3</b>: The version of GCC 3.3.3 commonly shipped with
 522    Cygwin does not work.  Please <a href="GCCFEBuildInstrs.html#cygwin">upgrade
 523    to a newer version</a> if possible.</p>
 524 <p><b>SuSE GCC 3.3.3</b>: The version of GCC 3.3.3 shipped with SuSE 9.1 (and
 525    possibly others) does not compile LLVM correctly (it appears that exception
 526    handling is broken in some cases).  Please download the FSF 3.3.3 or upgrade
 527    to a newer version of GCC.</p>
 528 <p><b>GCC 3.4.0 on linux/x86 (32-bit)</b>: GCC miscompiles portions of the
 529    code generator, causing an infinite loop in the llvm-gcc build when built
 530    with optimizations enabled (i.e. a release build).</p>
 531 <p><b>GCC 3.4.2 on linux/x86 (32-bit)</b>: GCC miscompiles portions of the
 532    code generator at -O3, as with 3.4.0.  However gcc 3.4.2 (unlike 3.4.0)
 533    correctly compiles LLVM at -O2.  A work around is to build release LLVM
 534    builds with "make ENABLE_OPTIMIZED=1 OPTIMIZE_OPTION=-O2 ..."</p>
 535 <p><b>GCC 3.4.x on X86-64/amd64</b>: GCC <a href="http://llvm.org/PR1056">
 536    miscompiles portions of LLVM</a>.</p>
 537 <p><b>GCC 3.4.4 (CodeSourcery ARM 2005q3-2)</b>: this compiler miscompiles LLVM
 538    when building with optimizations enabled.  It appears to work with
 539    "<tt>make ENABLE_OPTIMIZED=1 OPTIMIZE_OPTION=-O1</tt>" or build a debug
 540    build.</p>
 541 <p><b>IA-64 GCC 4.0.0</b>: The IA-64 version of GCC 4.0.0 is known to
 542    miscompile LLVM.</p>
 543 <p><b>Apple Xcode 2.3</b>: GCC crashes when compiling LLVM at -O3 (which is the
 544    default with ENABLE_OPTIMIZED=1.  To work around this, build with
 545    "ENABLE_OPTIMIZED=1 OPTIMIZE_OPTION=-O2".</p>
 546 <p><b>GCC 4.1.1</b>: GCC fails to build LLVM with template concept check errors
 547       compiling some files.  At the time of this writing, GCC mainline (4.2)
 548       did not share the problem.</p>
 549 <p><b>GCC 4.1.1 on X86-64/amd64</b>: GCC <a href="http://llvm.org/PR1063">
 550    miscompiles portions of LLVM</a> when compiling llvm itself into 64-bit
 551    code.  LLVM will appear to mostly work but will be buggy, e.g. failing
 552    portions of its testsuite.</p>
 553 <p><b>GCC 4.1.2 on OpenSUSE</b>: Seg faults during libstdc++ build and on x86_64
 554 platforms compiling md5.c gets a mangled constant.</p>
 555 <p><b>GCC 4.1.2 (20061115 (prerelease) (Debian 4.1.1-21)) on Debian</b>: Appears
 556 to miscompile parts of LLVM 2.4. One symptom is ValueSymbolTable complaining
 557 about symbols remaining in the table on destruction.</p>
 558 <p><b>GCC 4.1.2 20071124 (Red Hat 4.1.2-42)</b>: Suffers from the same symptoms
 559 as the previous one. It appears to work with ENABLE_OPTIMIZED=0 (the default).</p>
 560 <p><b>Cygwin GCC 4.3.2 20080827 (beta) 2</b>:
 561   Users <a href="http://llvm.org/PR4145">reported</a> various problems related
 562   with link errors when using this GCC version.</p>
 563 <p><b>Debian GCC 4.3.2 on X86</b>: Crashes building some files in LLVM 2.6.</p>
 564 <p><b>GCC 4.3.3 (Debian 4.3.3-10) on ARM</b>: Miscompiles parts of LLVM 2.6
 565 when optimizations are turned on. The symptom is an infinite loop in
 566 FoldingSetImpl::RemoveNode while running the code generator.</p>
 567 <p><b>GNU ld 2.16.X</b>. Some 2.16.X versions of the ld linker will produce very
 568 long warning messages complaining that some ".gnu.linkonce.t.*" symbol was
 569 defined in a discarded section. You can safely ignore these messages as they are
 570 erroneous and the linkage is correct.  These messages disappear using ld
 571 2.17.</p>
 572
 573 <p><b>GNU binutils 2.17</b>: Binutils 2.17 contains <a
 574 href="http://sourceware.org/bugzilla/show_bug.cgi?id=3111">a bug</a> which
 575 causes huge link times (minutes instead of seconds) when building LLVM.  We
 576 recommend upgrading to a newer version (2.17.50.0.4 or later).</p>
 577
 578 <p><b>GNU Binutils 2.19.1 Gold</b>: This version of Gold contained
 579 <a href="http://sourceware.org/bugzilla/show_bug.cgi?id=9836">a bug</a>
 580 which causes intermittent failures when building LLVM with position independent
 581 code.  The symptom is an error about cyclic dependencies.  We recommend
 582 upgrading to a newer version of Gold.</p>
 583
 584 </div>
 585
 586
 587
 588 <!-- *********************************************************************** -->
 589 <div class="doc_section">
 590   <a name="starting"><b>Getting Started with LLVM</b></a>
 591 </div>
 592 <!-- *********************************************************************** -->
 593
 594 <div class="doc_text">
 595
 596 <p>The remainder of this guide is meant to get you up and running with
 597 LLVM and to give you some basic information about the LLVM environment.</p>
 598
 599 <p>The later sections of this guide describe the <a
 600 href="#layout">general layout</a> of the the LLVM source tree, a <a
 601 href="#tutorial">simple example</a> using the LLVM tool chain, and <a
 602 href="#links">links</a> to find more information about LLVM or to get
 603 help via e-mail.</p>
 604 </div>
 605
 606 <!-- ======================================================================= -->
 607 <div class="doc_subsection">
 608   <a name="terminology">Terminology and Notation</a>
 609 </div>
 610
 611 <div class="doc_text">
 612
 613 <p>Throughout this manual, the following names are used to denote paths
 614 specific to the local system and working environment.  <i>These are not
 615 environment variables you need to set but just strings used in the rest
 616 of this document below</i>.  In any of the examples below, simply replace
 617 each of these names with the appropriate pathname on your local system.
 618 All these paths are absolute:</p>
 619
 620 <dl>
 621     <dt>SRC_ROOT
 622     <dd>
 623     This is the top level directory of the LLVM source tree.
 624     <br><br>
 625
 626     <dt>OBJ_ROOT
 627     <dd>
 628     This is the top level directory of the LLVM object tree (i.e. the
 629     tree where object files and compiled programs will be placed.  It
 630     can be the same as SRC_ROOT).
 631     <br><br>
 632
 633     <dt>LLVMGCCDIR
 634     <dd>
 635     This is where the LLVM GCC Front End is installed.
 636     <p>
 637     For the pre-built GCC front end binaries, the LLVMGCCDIR is
 638     <tt>llvm-gcc/<i>platform</i>/llvm-gcc</tt>.
 639 </dl>
 640
 641 </div>
 642
 643 <!-- ======================================================================= -->
 644 <div class="doc_subsection">
 645   <a name="environment">Setting Up Your Environment</a>
 646 </div>
 647
 648 <div class="doc_text">
 649
 650 <p>
 651 In order to compile and use LLVM, you may need to set some environment
 652 variables.
 653
 654 <dl>
 655   <dt><tt>LLVM_LIB_SEARCH_PATH</tt>=<tt>/path/to/your/bitcode/libs</tt></dt>
 656   <dd>[Optional] This environment variable helps LLVM linking tools find the
 657   locations of your bitcode libraries. It is provided only as a
 658   convenience since you can specify the paths using the -L options of the
 659   tools and the C/C++ front-end will automatically use the bitcode files
 660   installed in its
 661   <tt>lib</tt> directory.</dd>
 662 </dl>
 663
 664 </div>
 665
 666 <!-- ======================================================================= -->
 667 <div class="doc_subsection">
 668   <a name="unpack">Unpacking the LLVM Archives</a>
 669 </div>
 670
 671 <div class="doc_text">
 672
 673 <p>
 674 If you have the LLVM distribution, you will need to unpack it before you
 675 can begin to compile it.  LLVM is distributed as a set of two files: the LLVM
 676 suite and the LLVM GCC front end compiled for your platform.  There is an
 677 additional test suite that is optional.  Each file is a TAR archive that is
 678 compressed with the gzip program.
 679 </p>
 680
 681 <p>The files are as follows, with <em>x.y</em> marking the version number:
 682 <dl>
 683   <dt><tt>llvm-x.y.tar.gz</tt></dt>
 684   <dd>Source release for the LLVM libraries and tools.<br></dd>
 685
 686   <dt><tt>llvm-test-x.y.tar.gz</tt></dt>
 687   <dd>Source release for the LLVM test suite.</dd>
 688
 689   <dt><tt>llvm-gcc-4.2-x.y.source.tar.gz</tt></dt>
 690   <dd>Source release of the llvm-gcc-4.2 front end.  See README.LLVM in the root
 691       directory for build instructions.<br></dd>
 692
 693   <dt><tt>llvm-gcc-4.2-x.y-platform.tar.gz</tt></dt>
 694   <dd>Binary release of the llvm-gcc-4.2 front end for a specific platform.<br></dd>
 695
 696 </dl>
 697
 698 </div>
 699
 700 <!-- ======================================================================= -->
 701 <div class="doc_subsection">
 702   <a name="checkout">Checkout LLVM from Subversion</a>
 703 </div>
 704
 705 <div class="doc_text">
 706
 707 <p>If you have access to our Subversion repository, you can get a fresh copy of
 708 the entire source code.  All you need to do is check it out from Subversion as
 709 follows:</p>
 710
 711 <ul>
 712   <li><tt>cd <i>where-you-want-llvm-to-live</i></tt></li>
 713   <li>Read-Only: <tt>svn co http://llvm.org/svn/llvm-project/llvm/trunk llvm</tt></li>
 714   <li>Read-Write:<tt>svn co https://user@llvm.org/svn/llvm-project/llvm/trunk
 715     llvm</tt></li>
 716 </ul>
 717
 718
 719 <p>This will create an '<tt>llvm</tt>' directory in the current
 720 directory and fully populate it with the LLVM source code, Makefiles,
 721 test directories, and local copies of documentation files.</p>
 722
 723 <p>If you want to get a specific release (as opposed to the most recent
 724 revision), you can checkout it from the '<tt>tags</tt>' directory (instead of
 725 '<tt>trunk</tt>'). The following releases are located in the following
 726 subdirectories of the '<tt>tags</tt>' directory:</p>
 727
 728 <ul>
 729 <li>Release 2.6: <b>RELEASE_26</b></li>
 730 <li>Release 2.5: <b>RELEASE_25</b></li>
 731 <li>Release 2.4: <b>RELEASE_24</b></li>
 732 <li>Release 2.3: <b>RELEASE_23</b></li>
 733 <li>Release 2.2: <b>RELEASE_22</b></li>
 734 <li>Release 2.1: <b>RELEASE_21</b></li>
 735 <li>Release 2.0: <b>RELEASE_20</b></li>
 736 <li>Release 1.9: <b>RELEASE_19</b></li>
 737 <li>Release 1.8: <b>RELEASE_18</b></li>
 738 <li>Release 1.7: <b>RELEASE_17</b></li>
 739 <li>Release 1.6: <b>RELEASE_16</b></li>
 740 <li>Release 1.5: <b>RELEASE_15</b></li>
 741 <li>Release 1.4: <b>RELEASE_14</b></li>
 742 <li>Release 1.3: <b>RELEASE_13</b></li>
 743 <li>Release 1.2: <b>RELEASE_12</b></li>
 744 <li>Release 1.1: <b>RELEASE_11</b></li>
 745 <li>Release 1.0: <b>RELEASE_1</b></li>
 746 </ul>
 747
 748 <p>If you would like to get the LLVM test suite (a separate package as of 1.4),
 749 you get it from the Subversion repository:</p>
 750
 751 <div class="doc_code">
 752 <pre>
 753 % cd llvm/projects
 754 % svn co http://llvm.org/svn/llvm-project/test-suite/trunk llvm-test
 755 </pre>
 756 </div>
 757
 758 <p>By placing it in the <tt>llvm/projects</tt>, it will be automatically
 759 configured by the LLVM configure script as well as automatically updated when
 760 you run <tt>svn update</tt>.</p>
 761
 762 <p>If you would like to get the GCC front end source code, you can also get it
 763 and build it yourself.  Please follow <a href="GCCFEBuildInstrs.html">these
 764 instructions</a> to successfully get and build the LLVM GCC front-end.</p>
 765
 766 </div>
 767
 768 <!-- ======================================================================= -->
 769 <div class="doc_subsection">
 770   <a name="installcf">Install the GCC Front End</a>
 771 </div>
 772
 773 <div class="doc_text">
 774
 775 <p>Before configuring and compiling the LLVM suite (or if you want to use just the LLVM
 776 GCC front end) you can optionally extract the front end from the binary distribution.
 777 It is used for running the llvm-test testsuite and for compiling C/C++ programs.  Note that
 778 you can optionally <a href="GCCFEBuildInstrs.html">build llvm-gcc yourself</a> after building the
 779 main LLVM repository.</p>
 780
 781 <p>To install the GCC front end, do the following (on Windows, use an archival tool
 782 like <a href="http://www.7-zip.org">7-zip</a> that understands gzipped tars):</p>
 783
 784 <ol>
 785   <li><tt>cd <i>where-you-want-the-front-end-to-live</i></tt></li>
 786   <li><tt>gunzip --stdout llvm-gcc-4.2-<i>version</i>-<i>platform</i>.tar.gz | tar -xvf
 787       -</tt></li>
 788 </ol>
 789
 790 <p>Once the binary is uncompressed, if you're using a *nix-based system, add a symlink for
 791 <tt>llvm-gcc</tt> and <tt>llvm-g++</tt> to some directory in your path.  If you're using a
 792 Windows-based system, add the <tt>bin</tt> subdirectory of your front end installation directory
 793 to your <tt>PATH</tt> environment variable.  For example, if you uncompressed the binary to
 794 <tt>c:\llvm-gcc</tt>, add <tt>c:\llvm-gcc\bin</tt> to your <tt>PATH</tt>.</p>
 795
 796 <p>If you now want to build LLVM from source, when you configure LLVM, it will
 797 automatically detect <tt>llvm-gcc</tt>'s presence (if it is in your path) enabling its
 798 use in llvm-test.  Note that you can always build or install <tt>llvm-gcc</tt> at any
 799 point after building the main LLVM repository: just reconfigure llvm and
 800 llvm-test will pick it up.
 801 </p>
 802
 803 <p>As a convenience for Windows users, the front end binaries for MinGW/x86 include
 804 versions of the required w32api and mingw-runtime binaries.  The last remaining step for
 805 Windows users is to simply uncompress the binary binutils package from
 806 <a href="http://mingw.org/">MinGW</a> into your front end installation directory.  While the
 807 front end installation steps are not quite the same as a typical manual MinGW installation,
 808 they should be similar enough to those who have previously installed MinGW on Windows systems.</p>
 809
 810 <p>To install binutils on Windows:</p>
 811
 812 <ol>
 813   <li><tt><i>download GNU Binutils from <a href="http://sourceforge.net/projects/mingw/files/">MinGW Downloads</a></i></tt></li>
 814   <li><tt>cd <i>where-you-uncompressed-the-front-end</i></tt></li>
 815   <li><tt><i>uncompress archived binutils directories (not the tar file) into the current directory</i></tt></li>
 816 </ol>
 817
 818 <p>The binary versions of the LLVM GCC front end may not suit all of your needs.  For
 819 example, the binary distribution may include an old version of a system header
 820 file, not "fix" a header file that needs to be fixed for GCC, or it may be linked with
 821 libraries not available on your system.  In cases like these, you may want to try
 822 <a href="GCCFEBuildInstrs.html">building the GCC front end from source</a>.  Thankfully,
 823 this is much easier now than it was in the past.</p>
 824
 825 <p>We also do not currently support updating of the GCC front end by manually overlaying
 826 newer versions of the w32api and mingw-runtime binary packages that may become available
 827 from MinGW.  At this time, it's best to think of the MinGW LLVM GCC front end binary as
 828 a self-contained convenience package that requires Windows users to simply download and
 829 uncompress the GNU Binutils binary package from the MinGW project.</p>
 830
 831 <p>Regardless of your platform, if you discover that installing the LLVM GCC front end
 832 binaries is not as easy as previously described, or you would like to suggest improvements,
 833 please let us know how you would like to see things improved by dropping us a note on our
 834 <a href="http://llvm.org/docs/#maillist">mailing list</a>.</p>
 835
 836 </div>
 837
 838 <!-- ======================================================================= -->
 839 <div class="doc_subsection">
 840   <a name="config">Local LLVM Configuration</a>
 841 </div>
 842
 843 <div class="doc_text">
 844
 845   <p>Once checked out from the Subversion repository, the LLVM suite source
 846   code must be
 847 configured via the <tt>configure</tt> script.  This script sets variables in the
 848 various <tt>*.in</tt> files, most notably <tt>llvm/Makefile.config</tt> and
 849 <tt>llvm/include/Config/config.h</tt>.  It also populates <i>OBJ_ROOT</i> with
 850 the Makefiles needed to begin building LLVM.</p>
 851
 852 <p>The following environment variables are used by the <tt>configure</tt>
 853 script to configure the build system:</p>
 854
 855 <table summary="LLVM configure script environment variables">
 856   <tr><th>Variable</th><th>Purpose</th></tr>
 857   <tr>
 858     <td>CC</td>
 859     <td>Tells <tt>configure</tt> which C compiler to use.  By default,
 860         <tt>configure</tt> will look for the first GCC C compiler in
 861         <tt>PATH</tt>.  Use this variable to override
 862         <tt>configure</tt>'s default behavior.</td>
 863   </tr>
 864   <tr>
 865     <td>CXX</td>
 866     <td>Tells <tt>configure</tt> which C++ compiler to use.  By default,
 867        <tt>configure</tt> will look for the first GCC C++ compiler in
 868        <tt>PATH</tt>.  Use this variable to override
 869        <tt>configure</tt>'s default behavior.</td>
 870   </tr>
 871 </table>
 872
 873 <p>The following options can be used to set or enable LLVM specific options:</p>
 874
 875 <dl>
 876   <dt><i>--with-llvmgccdir</i></dt>
 877   <dd>Path to the LLVM C/C++ FrontEnd to be used with this LLVM configuration.
 878   The value of this option should specify the full pathname of the C/C++ Front
 879   End to be used. If this option is not provided, the PATH will be searched for
 880   a program named <i>llvm-gcc</i> and the C/C++ FrontEnd install directory will
 881   be inferred from the path found. If the option is not given, and no llvm-gcc
 882   can be found in the path then a warning will be produced by
 883   <tt>configure</tt> indicating this situation. LLVM may still be built with
 884   the <tt>tools-only</tt> target but attempting to build the runtime libraries
 885   will fail as these libraries require llvm-gcc and llvm-g++. See
 886   <a href="#installcf">Install the GCC Front End</a> for details on installing
 887   the C/C++ Front End. See
 888   <a href="GCCFEBuildInstrs.html">Bootstrapping the LLVM C/C++ Front-End</a>
 889   for details on building the C/C++ Front End.</dd>
 890   <dt><i>--with-tclinclude</i></dt>
 891   <dd>Path to the tcl include directory under which <tt>tclsh</tt> can be
 892   found. Use this if you have multiple tcl installations on your machine and you
 893   want to use a specific one (8.x) for LLVM. LLVM only uses tcl for running the
 894   dejagnu based test suite in <tt>llvm/test</tt>. If you don't specify this
 895   option, the LLVM configure script will search for the tcl 8.4 and 8.3
 896   releases.
 897   <br><br>
 898   </dd>
 899   <dt><i>--enable-optimized</i></dt>
 900   <dd>
 901     Enables optimized compilation (debugging symbols are removed
 902     and GCC optimization flags are enabled). Note that this is the default
 903     setting     if you are using the LLVM distribution. The default behavior
 904     of an Subversion checkout is to use an unoptimized build (also known as a
 905     debug build).
 906     <br><br>
 907   </dd>
 908   <dt><i>--enable-debug-runtime</i></dt>
 909   <dd>
 910     Enables debug symbols in the runtime libraries. The default is to strip
 911     debug symbols from the runtime libraries.
 912   </dd>
 913   <dt><i>--enable-jit</i></dt>
 914   <dd>
 915     Compile the Just In Time (JIT) compiler functionality.  This is not
 916     available
 917     on all platforms.  The default is dependent on platform, so it is best
 918     to explicitly enable it if you want it.
 919     <br><br>
 920   </dd>
 921   <dt><i>--enable-targets=</i><tt>target-option</tt></dt>
 922   <dd>Controls which targets will be built and linked into llc. The default
 923   value for <tt>target_options</tt> is "all" which builds and links all
 924   available targets.  The value "host-only" can be specified to build only a
 925   native compiler (no cross-compiler targets available). The "native" target is
 926   selected as the target of the build host. You can also specify a comma
 927   separated list of target names that you want available in llc. The target
 928   names use all lower case. The current set of targets is: <br>
 929   <tt>alpha, ia64, powerpc, skeleton, sparc, x86</tt>.
 930   <br><br></dd>
 931   <dt><i>--enable-doxygen</i></dt>
 932   <dd>Look for the doxygen program and enable construction of doxygen based
 933   documentation from the source code. This is disabled by default because
 934   generating the documentation can take a long time and producess 100s of
 935   megabytes of output.</dd>
 936   <dt><i>--with-udis86</i></dt>
 937   <dd>LLVM can use external disassembler library for various purposes (now it's
 938   used only for examining code produced by JIT). This option will enable usage
 939   of <a href="http://udis86.sourceforge.net/">udis86</a> x86 (both 32 and 64
 940   bits) disassembler library.</dd>
 941 </dl>
 942
 943 <p>To configure LLVM, follow these steps:</p>
 944
 945 <ol>
 946     <li><p>Change directory into the object root directory:</p>
 947
 948     <div class="doc_code"><pre>% cd <i>OBJ_ROOT</i></pre></div></li>
 949
 950     <li><p>Run the <tt>configure</tt> script located in the LLVM source
 951     tree:</p>
 952
 953     <div class="doc_code">
 954     <pre>% <i>SRC_ROOT</i>/configure --prefix=/install/path [other options]</pre>
 955     </div></li>
 956 </ol>
 957
 958 </div>
 959
 960 <!-- ======================================================================= -->
 961 <div class="doc_subsection">
 962   <a name="compile">Compiling the LLVM Suite Source Code</a>
 963 </div>
 964
 965 <div class="doc_text">
 966
 967 <p>Once you have configured LLVM, you can build it.  There are three types of
 968 builds:</p>
 969
 970 <dl>
 971     <dt>Debug Builds
 972     <dd>
 973     These builds are the default when one is using an Subversion checkout and
 974     types <tt>gmake</tt> (unless the <tt>--enable-optimized</tt> option was
 975     used during configuration).  The build system will compile the tools and
 976     libraries with debugging information.  To get a Debug Build using the
 977     LLVM distribution the <tt>--disable-optimized</tt> option must be passed
 978     to <tt>configure</tt>.
 979     <br><br>
 980
 981     <dt>Release (Optimized) Builds
 982     <dd>
 983     These builds are enabled with the <tt>--enable-optimized</tt> option to
 984     <tt>configure</tt> or by specifying <tt>ENABLE_OPTIMIZED=1</tt> on the
 985     <tt>gmake</tt> command line.  For these builds, the build system will
 986     compile the tools and libraries with GCC optimizations enabled and strip
 987     debugging information from the libraries and executables it generates.
 988     Note that Release Builds are default when using an LLVM distribution.
 989     <br><br>
 990
 991     <dt>Profile Builds
 992     <dd>
 993     These builds are for use with profiling.  They compile profiling
 994     information into the code for use with programs like <tt>gprof</tt>.
 995     Profile builds must be started by specifying <tt>ENABLE_PROFILING=1</tt>
 996     on the <tt>gmake</tt> command line.
 997 </dl>
 998
 999 <p>Once you have LLVM configured, you can build it by entering the
1000 <i>OBJ_ROOT</i> directory and issuing the following command:</p>
1001
1002 <div class="doc_code"><pre>% gmake</pre></div>
1003
1004 <p>If the build fails, please <a href="#brokengcc">check here</a> to see if you
1005 are using a version of GCC that is known not to compile LLVM.</p>
1006
1007 <p>
1008 If you have multiple processors in your machine, you may wish to use some of
1009 the parallel build options provided by GNU Make.  For example, you could use the
1010 command:</p>
1011
1012 <div class="doc_code"><pre>% gmake -j2</pre></div>
1013
1014 <p>There are several special targets which are useful when working with the LLVM
1015 source code:</p>
1016
1017 <dl>
1018   <dt><tt>gmake clean</tt>
1019   <dd>
1020   Removes all files generated by the build.  This includes object files,
1021   generated C/C++ files, libraries, and executables.
1022   <br><br>
1023
1024   <dt><tt>gmake dist-clean</tt>
1025   <dd>
1026   Removes everything that <tt>gmake clean</tt> does, but also removes files
1027   generated by <tt>configure</tt>.  It attempts to return the source tree to the
1028   original state in which it was shipped.
1029   <br><br>
1030
1031   <dt><tt>gmake install</tt>
1032   <dd>
1033   Installs LLVM header files, libraries, tools, and documentation in a
1034   hierarchy
1035   under $PREFIX, specified with <tt>./configure --prefix=[dir]</tt>, which
1036   defaults to <tt>/usr/local</tt>.
1037   <br><br>
1038
1039   <dt><tt>gmake -C runtime install-bytecode</tt>
1040   <dd>
1041   Assuming you built LLVM into $OBJDIR, when this command is run, it will
1042   install bitcode libraries into the GCC front end's bitcode library
1043   directory.  If you need to update your bitcode libraries,
1044   this is the target to use once you've built them.
1045   <br><br>
1046 </dl>
1047
1048 <p>Please see the <a href="MakefileGuide.html">Makefile Guide</a> for further
1049 details on these <tt>make</tt> targets and descriptions of other targets
1050 available.</p>
1051
1052 <p>It is also possible to override default values from <tt>configure</tt> by
1053 declaring variables on the command line.  The following are some examples:</p>
1054
1055 <dl>
1056   <dt><tt>gmake ENABLE_OPTIMIZED=1</tt>
1057   <dd>
1058   Perform a Release (Optimized) build.
1059   <br><br>
1060
1061   <dt><tt>gmake ENABLE_OPTIMIZED=1 DISABLE_ASSERTIONS=1</tt>
1062   <dd>
1063   Perform a Release (Optimized) build without assertions enabled.
1064   <br><br>
1065
1066   <dt><tt>gmake ENABLE_OPTIMIZED=0</tt>
1067   <dd>
1068   Perform a Debug build.
1069   <br><br>
1070
1071   <dt><tt>gmake ENABLE_PROFILING=1</tt>
1072   <dd>
1073   Perform a Profiling build.
1074   <br><br>
1075
1076   <dt><tt>gmake VERBOSE=1</tt>
1077   <dd>
1078   Print what <tt>gmake</tt> is doing on standard output.
1079   <br><br>
1080
1081   <dt><tt>gmake TOOL_VERBOSE=1</tt></dt>
1082   <dd>Ask each tool invoked by the makefiles to print out what it is doing on
1083   the standard output. This also implies <tt>VERBOSE=1</tt>.
1084   <br><br></dd>
1085 </dl>
1086
1087 <p>Every directory in the LLVM object tree includes a <tt>Makefile</tt> to build
1088 it and any subdirectories that it contains.  Entering any directory inside the
1089 LLVM object tree and typing <tt>gmake</tt> should rebuild anything in or below
1090 that directory that is out of date.</p>
1091
1092 </div>
1093
1094 <!-- ======================================================================= -->
1095 <div class="doc_subsection">
1096   <a name="cross-compile">Cross-Compiling LLVM</a>
1097 </div>
1098
1099 <div class="doc_text">
1100   <p>It is possible to cross-compile LLVM itself. That is, you can create LLVM
1101   executables and libraries to be hosted on a platform different from the
1102   platform where they are build (a Canadian Cross build). To configure a
1103   cross-compile, supply the configure script with <tt>--build</tt> and
1104   <tt>--host</tt> options that are different. The values of these options must
1105   be legal target triples that your GCC compiler supports.</p>
1106
1107   <p>The result of such a build is executables that are not runnable on
1108   on the build host (--build option) but can be executed on the compile host
1109   (--host option).</p>
1110 </div>
1111
1112 <!-- ======================================================================= -->
1113 <div class="doc_subsection">
1114   <a name="objfiles">The Location of LLVM Object Files</a>
1115 </div>
1116
1117 <div class="doc_text">
1118
1119 <p>The LLVM build system is capable of sharing a single LLVM source tree among
1120 several LLVM builds.  Hence, it is possible to build LLVM for several different
1121 platforms or configurations using the same source tree.</p>
1122
1123 <p>This is accomplished in the typical autoconf manner:</p>
1124
1125 <ul>
1126   <li><p>Change directory to where the LLVM object files should live:</p>
1127
1128       <div class="doc_code"><pre>% cd <i>OBJ_ROOT</i></pre></div></li>
1129
1130   <li><p>Run the <tt>configure</tt> script found in the LLVM source
1131       directory:</p>
1132
1133       <div class="doc_code"><pre>% <i>SRC_ROOT</i>/configure</pre></div></li>
1134 </ul>
1135
1136 <p>The LLVM build will place files underneath <i>OBJ_ROOT</i> in directories
1137 named after the build type:</p>
1138
1139 <dl>
1140   <dt>Debug Builds
1141   <dd>
1142   <dl>
1143     <dt>Tools
1144     <dd><tt><i>OBJ_ROOT</i>/Debug/bin</tt>
1145     <dt>Libraries
1146     <dd><tt><i>OBJ_ROOT</i>/Debug/lib</tt>
1147   </dl>
1148   <br><br>
1149
1150   <dt>Release Builds
1151   <dd>
1152   <dl>
1153     <dt>Tools
1154     <dd><tt><i>OBJ_ROOT</i>/Release/bin</tt>
1155     <dt>Libraries
1156     <dd><tt><i>OBJ_ROOT</i>/Release/lib</tt>
1157   </dl>
1158   <br><br>
1159
1160   <dt>Profile Builds
1161   <dd>
1162   <dl>
1163     <dt>Tools
1164     <dd><tt><i>OBJ_ROOT</i>/Profile/bin</tt>
1165     <dt>Libraries
1166     <dd><tt><i>OBJ_ROOT</i>/Profile/lib</tt>
1167   </dl>
1168 </dl>
1169
1170 </div>
1171
1172 <!-- ======================================================================= -->
1173 <div class="doc_subsection">
1174   <a name="optionalconfig">Optional Configuration Items</a>
1175 </div>
1176
1177 <div class="doc_text">
1178
1179 <p>
1180 If you're running on a Linux system that supports the "<a
1181 href="http://www.tat.physik.uni-tuebingen.de/~rguenth/linux/binfmt_misc.html">binfmt_misc</a>"
1182 module, and you have root access on the system, you can set your system up to
1183 execute LLVM bitcode files directly. To do this, use commands like this (the
1184 first command may not be required if you are already using the module):</p>
1185
1186 <div class="doc_code">
1187 <pre>
1188 $ mount -t binfmt_misc none /proc/sys/fs/binfmt_misc
1189 $ echo ':llvm:M::BC::/path/to/lli:' &gt; /proc/sys/fs/binfmt_misc/register
1190 $ chmod u+x hello.bc   (if needed)
1191 $ ./hello.bc
1192 </pre>
1193 </div>
1194
1195 <p>
1196 This allows you to execute LLVM bitcode files directly.  On Debian, you
1197 can also use this command instead of the 'echo' command above:</p>
1198 </p>
1199
1200 <div class="doc_code">
1201 <pre>
1202 $ sudo update-binfmts --install llvm /path/to/lli --magic 'BC'
1203 </pre>
1204 </div>
1205
1206 </div>
1207
1208 <!-- *********************************************************************** -->
1209 <div class="doc_section">
1210   <a name="layout"><b>Program Layout</b></a>
1211 </div>
1212 <!-- *********************************************************************** -->
1213
1214 <div class="doc_text">
1215
1216 <p>One useful source of information about the LLVM source base is the LLVM <a
1217 href="http://www.doxygen.org">doxygen</a> documentation available at <tt><a
1218 href="http://llvm.org/doxygen/">http://llvm.org/doxygen/</a></tt>.
1219 The following is a brief introduction to code layout:</p>
1220
1221 </div>
1222
1223 <!-- ======================================================================= -->
1224 <div class="doc_subsection"><a name="examples"><tt>llvm/examples</tt></a></div>
1225 <div class="doc_text">
1226   <p>This directory contains some simple examples of how to use the LLVM IR and
1227   JIT.</p>
1228 </div>
1229
1230 <!-- ======================================================================= -->
1231 <div class="doc_subsection"><a name="include"><tt>llvm/include</tt></a></div>
1232 <div class="doc_text">
1233
1234 <p>This directory contains public header files exported from the LLVM
1235 library. The three main subdirectories of this directory are:</p>
1236
1237 <dl>
1238   <dt><tt><b>llvm/include/llvm</b></tt></dt>
1239   <dd>This directory contains all of the LLVM specific header files.  This
1240   directory also has subdirectories for different portions of LLVM:
1241   <tt>Analysis</tt>, <tt>CodeGen</tt>, <tt>Target</tt>, <tt>Transforms</tt>,
1242   etc...</dd>
1243
1244   <dt><tt><b>llvm/include/llvm/Support</b></tt></dt>
1245   <dd>This directory contains generic support libraries that are provided with
1246   LLVM but not necessarily specific to LLVM. For example, some C++ STL utilities
1247   and a Command Line option processing library store their header files here.
1248   </dd>
1249
1250   <dt><tt><b>llvm/include/llvm/Config</b></tt></dt>
1251   <dd>This directory contains header files configured by the <tt>configure</tt>
1252   script.  They wrap "standard" UNIX and C header files.  Source code can
1253   include these header files which automatically take care of the conditional
1254   #includes that the <tt>configure</tt> script generates.</dd>
1255 </dl>
1256 </div>
1257
1258 <!-- ======================================================================= -->
1259 <div class="doc_subsection"><a name="lib"><tt>llvm/lib</tt></a></div>
1260 <div class="doc_text">
1261
1262 <p>This directory contains most of the source files of the LLVM system. In LLVM,
1263 almost all code exists in libraries, making it very easy to share code among the
1264 different <a href="#tools">tools</a>.</p>
1265
1266 <dl>
1267   <dt><tt><b>llvm/lib/VMCore/</b></tt></dt>
1268   <dd> This directory holds the core LLVM source files that implement core
1269   classes like Instruction and BasicBlock.</dd>
1270
1271   <dt><tt><b>llvm/lib/AsmParser/</b></tt></dt>
1272   <dd>This directory holds the source code for the LLVM assembly language parser
1273   library.</dd>
1274
1275   <dt><tt><b>llvm/lib/BitCode/</b></tt></dt>
1276   <dd>This directory holds code for reading and write LLVM bitcode.</dd>
1277
1278   <dt><tt><b>llvm/lib/Analysis/</b></tt><dd>This directory contains a variety of
1279   different program analyses, such as Dominator Information, Call Graphs,
1280   Induction Variables, Interval Identification, Natural Loop Identification,
1281   etc.</dd>
1282
1283   <dt><tt><b>llvm/lib/Transforms/</b></tt></dt>
1284   <dd> This directory contains the source code for the LLVM to LLVM program
1285   transformations, such as Aggressive Dead Code Elimination, Sparse Conditional
1286   Constant Propagation, Inlining, Loop Invariant Code Motion, Dead Global
1287   Elimination, and many others.</dd>
1288
1289   <dt><tt><b>llvm/lib/Target/</b></tt></dt>
1290   <dd> This directory contains files that describe various target architectures
1291   for code generation.  For example, the <tt>llvm/lib/Target/X86</tt>
1292   directory holds the X86 machine description while
1293   <tt>llvm/lib/Target/CBackend</tt> implements the LLVM-to-C converter.</dd>
1294
1295   <dt><tt><b>llvm/lib/CodeGen/</b></tt></dt>
1296   <dd> This directory contains the major parts of the code generator: Instruction
1297   Selector, Instruction Scheduling, and Register Allocation.</dd>
1298
1299   <dt><tt><b>llvm/lib/Debugger/</b></tt></dt>
1300   <dd> This directory contains the source level debugger library that makes
1301   it possible to instrument LLVM programs so that a debugger could identify
1302   source code locations at which the program is executing.</dd>
1303
1304   <dt><tt><b>llvm/lib/ExecutionEngine/</b></tt></dt>
1305   <dd> This directory contains libraries for executing LLVM bitcode directly
1306   at runtime in both interpreted and JIT compiled fashions.</dd>
1307
1308   <dt><tt><b>llvm/lib/Support/</b></tt></dt>
1309   <dd> This directory contains the source code that corresponds to the header
1310   files located in <tt>llvm/include/Support/</tt>.</dd>
1311
1312   <dt><tt><b>llvm/lib/System/</b></tt></dt>
1313   <dd>This directory contains the operating system abstraction layer that
1314   shields LLVM from platform-specific coding.</dd>
1315 </dl>
1316
1317 </div>
1318
1319 <!-- ======================================================================= -->
1320 <div class="doc_subsection"><a name="projects"><tt>llvm/projects</tt></a></div>
1321 <div class="doc_text">
1322   <p>This directory contains projects that are not strictly part of LLVM but are
1323   shipped with LLVM. This is also the directory where you should create your own
1324   LLVM-based projects. See <tt>llvm/projects/sample</tt> for an example of how
1325   to set up your own project.</p>
1326 </div>
1327
1328 <!-- ======================================================================= -->
1329 <div class="doc_subsection"><a name="runtime"><tt>llvm/runtime</tt></a></div>
1330 <div class="doc_text">
1331
1332 <p>This directory contains libraries which are compiled into LLVM bitcode and
1333 used when linking programs with the GCC front end.  Most of these libraries are
1334 skeleton versions of real libraries; for example, libc is a stripped down
1335 version of glibc.</p>
1336
1337 <p>Unlike the rest of the LLVM suite, this directory needs the LLVM GCC front
1338 end to compile.</p>
1339
1340 </div>
1341
1342 <!-- ======================================================================= -->
1343 <div class="doc_subsection"><a name="test"><tt>llvm/test</tt></a></div>
1344 <div class="doc_text">
1345   <p>This directory contains feature and regression tests and other basic sanity
1346   checks on the LLVM infrastructure. These are intended to run quickly and cover
1347   a lot of territory without being exhaustive.</p>
1348 </div>
1349
1350 <!-- ======================================================================= -->
1351 <div class="doc_subsection"><a name="llvmtest"><tt>test-suite</tt></a></div>
1352 <div class="doc_text">
1353   <p>This is not a directory in the normal llvm module; it is a separate
1354   Subversion
1355   module that must be checked out (usually to <tt>projects/test-suite</tt>).
1356   This
1357   module contains a comprehensive correctness, performance, and benchmarking
1358   test
1359   suite for LLVM. It is a separate Subversion module because not every LLVM
1360   user is
1361   interested in downloading or building such a comprehensive test suite. For
1362   further details on this test suite, please see the
1363   <a href="TestingGuide.html">Testing Guide</a> document.</p>
1364 </div>
1365
1366 <!-- ======================================================================= -->
1367 <div class="doc_subsection"><a name="tools"><tt>llvm/tools</tt></a></div>
1368 <div class="doc_text">
1369
1370 <p>The <b>tools</b> directory contains the executables built out of the
1371 libraries above, which form the main part of the user interface.  You can
1372 always get help for a tool by typing <tt>tool_name -help</tt>.  The
1373 following is a brief introduction to the most important tools.  More detailed
1374 information is in the <a href="CommandGuide/index.html">Command Guide</a>.</p>
1375
1376 <dl>
1377
1378   <dt><tt><b>bugpoint</b></tt></dt>
1379   <dd><tt>bugpoint</tt> is used to debug
1380   optimization passes or code generation backends by narrowing down the
1381   given test case to the minimum number of passes and/or instructions that
1382   still cause a problem, whether it is a crash or miscompilation. See <a
1383   href="HowToSubmitABug.html">HowToSubmitABug.html</a> for more information
1384   on using <tt>bugpoint</tt>.</dd>
1385
1386   <dt><tt><b>llvmc</b></tt></dt>
1387   <dd>The LLVM Compiler Driver. This program can
1388   be configured to utilize both LLVM and non-LLVM compilation tools to enable
1389   pre-processing, translation, optimization, assembly, and linking of programs
1390   all from one command line. <tt>llvmc</tt> also takes care of processing the
1391   dependent libraries found in bitcode. This reduces the need to get the
1392   traditional <tt>-l&lt;name&gt;</tt> options right on the command line. Please
1393   note that this tool, while functional, is still experimental and not feature
1394   complete.</dd>
1395
1396   <dt><tt><b>llvm-ar</b></tt></dt>
1397   <dd>The archiver produces an archive containing
1398   the given LLVM bitcode files, optionally with an index for faster
1399   lookup.</dd>
1400
1401   <dt><tt><b>llvm-as</b></tt></dt>
1402   <dd>The assembler transforms the human readable LLVM assembly to LLVM
1403   bitcode.</dd>
1404
1405   <dt><tt><b>llvm-dis</b></tt></dt>
1406   <dd>The disassembler transforms the LLVM bitcode to human readable
1407   LLVM assembly.</dd>
1408
1409   <dt><tt><b>llvm-ld</b></tt></dt>
1410   <dd><tt>llvm-ld</tt> is a general purpose and extensible linker for LLVM.
1411   This is the linker invoked by <tt>llvmc</tt>. It performsn standard link time
1412   optimizations and allows optimization modules to be loaded and run so that
1413   language specific optimizations can be applied at link time.</dd>
1414
1415   <dt><tt><b>llvm-link</b></tt></dt>
1416   <dd><tt>llvm-link</tt>, not surprisingly, links multiple LLVM modules into
1417   a single program.</dd>
1418
1419   <dt><tt><b>lli</b></tt></dt>
1420   <dd><tt>lli</tt> is the LLVM interpreter, which
1421   can directly execute LLVM bitcode (although very slowly...). For architectures
1422   that support it (currently x86, Sparc, and PowerPC), by default, <tt>lli</tt>
1423   will function as a Just-In-Time compiler (if the functionality was compiled
1424   in), and will execute the code <i>much</i> faster than the interpreter.</dd>
1425
1426   <dt><tt><b>llc</b></tt></dt>
1427   <dd> <tt>llc</tt> is the LLVM backend compiler, which
1428   translates LLVM bitcode to a native code assembly file or to C code (with
1429   the -march=c option).</dd>
1430
1431   <dt><tt><b>llvm-gcc</b></tt></dt>
1432   <dd><tt>llvm-gcc</tt> is a GCC-based C frontend that has been retargeted to
1433   use LLVM as its backend instead of GCC's RTL backend. It can also emit LLVM
1434   bitcode or assembly (with the <tt>-emit-llvm</tt> option) instead of the
1435   usual machine code output.  It works just like any other GCC compiler,
1436   taking the typical <tt>-c, -S, -E, -o</tt> options that are typically used.
1437   Additionally, the the source code for <tt>llvm-gcc</tt> is available as a
1438   separate Subversion module.</dd>
1439
1440   <dt><tt><b>opt</b></tt></dt>
1441   <dd><tt>opt</tt> reads LLVM bitcode, applies a series of LLVM to LLVM
1442   transformations (which are specified on the command line), and then outputs
1443   the resultant bitcode.  The '<tt>opt -help</tt>' command is a good way to
1444   get a list of the program transformations available in LLVM.<br>
1445   <dd><tt>opt</tt> can also be used to run a specific analysis on an input
1446   LLVM bitcode file and print out the results.  It is primarily useful for
1447   debugging analyses, or familiarizing yourself with what an analysis does.</dd>
1448 </dl>
1449 </div>
1450
1451 <!-- ======================================================================= -->
1452 <div class="doc_subsection"><a name="utils"><tt>llvm/utils</tt></a></div>
1453 <div class="doc_text">
1454
1455 <p>This directory contains utilities for working with LLVM source code, and some
1456 of the utilities are actually required as part of the build process because they
1457 are code generators for parts of LLVM infrastructure.</p>
1458
1459 <dl>
1460   <dt><tt><b>codegen-diff</b></tt> <dd><tt>codegen-diff</tt> is a script
1461   that finds differences between code that LLC generates and code that LLI
1462   generates. This is a useful tool if you are debugging one of them,
1463   assuming that the other generates correct output. For the full user
1464   manual, run <tt>`perldoc codegen-diff'</tt>.<br><br>
1465
1466   <dt><tt><b>emacs/</b></tt> <dd>The <tt>emacs</tt> directory contains
1467   syntax-highlighting files which will work with Emacs and XEmacs editors,
1468   providing syntax highlighting support for LLVM assembly files and TableGen
1469   description files. For information on how to use the syntax files, consult
1470   the <tt>README</tt> file in that directory.<br><br>
1471
1472   <dt><tt><b>getsrcs.sh</b></tt> <dd>The <tt>getsrcs.sh</tt> script finds
1473   and outputs all non-generated source files, which is useful if one wishes
1474   to do a lot of development across directories and does not want to
1475   individually find each file. One way to use it is to run, for example:
1476   <tt>xemacs `utils/getsources.sh`</tt> from the top of your LLVM source
1477   tree.<br><br>
1478
1479   <dt><tt><b>llvmgrep</b></tt></dt>
1480   <dd>This little tool performs an "egrep -H -n" on each source file in LLVM and
1481   passes to it a regular expression provided on <tt>llvmgrep</tt>'s command
1482   line. This is a very efficient way of searching the source base for a
1483   particular regular expression.</dd>
1484
1485   <dt><tt><b>makellvm</b></tt> <dd>The <tt>makellvm</tt> script compiles all
1486   files in the current directory and then compiles and links the tool that
1487   is the first argument. For example, assuming you are in the directory
1488   <tt>llvm/lib/Target/Sparc</tt>, if <tt>makellvm</tt> is in your path,
1489   simply running <tt>makellvm llc</tt> will make a build of the current
1490   directory, switch to directory <tt>llvm/tools/llc</tt> and build it,
1491   causing a re-linking of LLC.<br><br>
1492
1493   <dt><tt><b>NewNightlyTest.pl</b></tt> and
1494   <tt><b>NightlyTestTemplate.html</b></tt> <dd>These files are used in a
1495   cron script to generate nightly status reports of the functionality of
1496   tools, and the results can be seen by following the appropriate link on
1497   the <a href="http://llvm.org/">LLVM homepage</a>.<br><br>
1498
1499   <dt><tt><b>TableGen/</b></tt> <dd>The <tt>TableGen</tt> directory contains
1500   the tool used to generate register descriptions, instruction set
1501   descriptions, and even assemblers from common TableGen description
1502   files.<br><br>
1503
1504   <dt><tt><b>vim/</b></tt> <dd>The <tt>vim</tt> directory contains
1505   syntax-highlighting files which will work with the VIM editor, providing
1506   syntax highlighting support for LLVM assembly files and TableGen
1507   description files. For information on how to use the syntax files, consult
1508   the <tt>README</tt> file in that directory.<br><br>
1509
1510 </dl>
1511
1512 </div>
1513
1514 <!-- ======================================================================= -->
1515 <div class="doc_subsection"><a name="win32"><tt>llvm/win32</tt></a></div>
1516 <div class="doc_text">
1517   <p>This directory contains build scripts and project files for use with
1518   Visual C++. This allows developers on Windows to build LLVM without the need
1519   for Cygwin. The contents of this directory should be considered experimental
1520   at this time.
1521   </p>
1522 </div>
1523 <!-- *********************************************************************** -->
1524 <div class="doc_section">
1525   <a name="tutorial">An Example Using the LLVM Tool Chain</a>
1526 </div>
1527 <!-- *********************************************************************** -->
1528
1529 <div class="doc_text">
1530 <p>This section gives an example of using LLVM.  llvm-gcc3 is now obsolete,
1531 so we only include instructions for llvm-gcc4.
1532 </p>
1533
1534 <p><b>Note:</b> The <i>gcc4</i> frontend's invocation is <b><i>considerably different</i></b>
1535 from the previous <i>gcc3</i> frontend. In particular, the <i>gcc4</i> frontend <b><i>does not</i></b>
1536 create bitcode by default: <i>gcc4</i> produces native code. As the example below illustrates,
1537 the '--emit-llvm' flag is needed to produce LLVM bitcode output. For <i>makefiles</i> and
1538 <i>configure</i> scripts, the CFLAGS variable needs '--emit-llvm' to produce bitcode
1539 output.</p>
1540 </div>
1541
1542 <!-- ======================================================================= -->
1543 <div class="doc_subsection"><a name="tutorial4">Example with llvm-gcc4</a></div>
1544
1545 <div class="doc_text">
1546
1547 <ol>
1548   <li><p>First, create a simple C file, name it 'hello.c':</p>
1549
1550 <div class="doc_code">
1551 <pre>
1552 #include &lt;stdio.h&gt;
1553
1554 int main() {
1555   printf("hello world\n");
1556   return 0;
1557 }
1558 </pre></div></li>
1559
1560   <li><p>Next, compile the C file into a native executable:</p>
1561
1562       <div class="doc_code"><pre>% llvm-gcc hello.c -o hello</pre></div>
1563
1564       <p>Note that llvm-gcc works just like GCC by default.  The standard -S and
1565         -c arguments work as usual (producing a native .s or .o file,
1566         respectively).</p></li>
1567
1568   <li><p>Next, compile the C file into a LLVM bitcode file:</p>
1569
1570       <div class="doc_code">
1571       <pre>% llvm-gcc -O3 -emit-llvm hello.c -c -o hello.bc</pre></div>
1572
1573       <p>The -emit-llvm option can be used with the -S or -c options to emit an
1574          LLVM ".ll" or ".bc" file (respectively) for the code.  This allows you
1575          to use the <a href="CommandGuide/index.html">standard LLVM tools</a> on
1576          the bitcode file.</p>
1577
1578       <p>Unlike llvm-gcc3, llvm-gcc4 correctly responds to -O[0123] arguments.
1579          </p></li>
1580
1581   <li><p>Run the program in both forms. To run the program, use:</p>
1582
1583       <div class="doc_code"><pre>% ./hello</pre></div>
1584
1585       <p>and</p>
1586
1587       <div class="doc_code"><pre>% lli hello.bc</pre></div>
1588
1589       <p>The second examples shows how to invoke the LLVM JIT, <a
1590        href="CommandGuide/html/lli.html">lli</a>.</p></li>
1591
1592   <li><p>Use the <tt>llvm-dis</tt> utility to take a look at the LLVM assembly
1593       code:</p>
1594
1595 <div class="doc_code">
1596 <pre>llvm-dis &lt; hello.bc | less</pre>
1597 </div></li>
1598
1599   <li><p>Compile the program to native assembly using the LLC code
1600       generator:</p>
1601
1602       <div class="doc_code"><pre>% llc hello.bc -o hello.s</pre></div></li>
1603
1604   <li><p>Assemble the native assembly language file into a program:</p>
1605
1606 <div class="doc_code">
1607 <pre>
1608 <b>Solaris:</b> % /opt/SUNWspro/bin/cc -xarch=v9 hello.s -o hello.native
1609
1610 <b>Others:</b>  % gcc hello.s -o hello.native
1611 </pre>
1612 </div></li>
1613
1614   <li><p>Execute the native code program:</p>
1615
1616       <div class="doc_code"><pre>% ./hello.native</pre></div>
1617
1618       <p>Note that using llvm-gcc to compile directly to native code (i.e. when
1619          the -emit-llvm option is not present) does steps 6/7/8 for you.</p>
1620         </li>
1621
1622 </ol>
1623
1624 </div>
1625
1626
1627 <!-- *********************************************************************** -->
1628 <div class="doc_section">
1629   <a name="problems">Common Problems</a>
1630 </div>
1631 <!-- *********************************************************************** -->
1632
1633 <div class="doc_text">
1634
1635 <p>If you are having problems building or using LLVM, or if you have any other
1636 general questions about LLVM, please consult the <a href="FAQ.html">Frequently
1637 Asked Questions</a> page.</p>
1638
1639 </div>
1640
1641 <!-- *********************************************************************** -->
1642 <div class="doc_section">
1643   <a name="links">Links</a>
1644 </div>
1645 <!-- *********************************************************************** -->
1646
1647 <div class="doc_text">
1648
1649 <p>This document is just an <b>introduction</b> on how to use LLVM to do
1650 some simple things... there are many more interesting and complicated things
1651 that you can do that aren't documented here (but we'll gladly accept a patch
1652 if you want to write something up!).  For more information about LLVM, check
1653 out:</p>
1654
1655 <ul>
1656   <li><a href="http://llvm.org/">LLVM homepage</a></li>
1657   <li><a href="http://llvm.org/doxygen/">LLVM doxygen tree</a></li>
1658   <li><a href="http://llvm.org/docs/Projects.html">Starting a Project
1659   that Uses LLVM</a></li>
1660 </ul>
1661
1662 </div>
1663
1664 <!-- *********************************************************************** -->
1665
1666 <hr>
1667 <address>
1668   <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
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1672
1673   <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
1674   <a href="http://llvm.x10sys.com/rspencer/">Reid Spencer</a><br>
1675   <a href="http://llvm.org">The LLVM Compiler Infrastructure</a><br>
1676   Last modified: $Date$
1677 </address>
1678 </body>
1679 </html>