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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     <ol>
 119       <li><tt>cd <i>where-you-want-the-C-front-end-to-live</i></tt></li>
 120       <li><tt>gunzip --stdout llvm-gcc-4.2-<i>version</i>-<i>platform</i>.tar.gz | tar -xvf -</tt>
 121       </li>
 122       <li>Note: If the binary extension is ".bz" use bunzip2 instead of gunzip.</li>
 123       <li>Add llvm-gcc's "bin" directory to your PATH variable.</li>
 124     </ol></li>
 125
 126   <li>Get the LLVM Source Code
 127   <ul>
 128     <li>With the distributed files (or use <a href="#checkout">SVN</a>):
 129     <ol>
 130       <li><tt>cd <i>where-you-want-llvm-to-live</i></tt>
 131       <li><tt>gunzip --stdout llvm-<i>version</i>.tar.gz | tar -xvf -</tt>
 132     </ol></li>
 133
 134   </ul></li>
 135
 136   <li><b>[Optional]</b> Get the Test Suite Source Code
 137   <ul>
 138     <li>With the distributed files (or use <a href="#checkout">SVN</a>):
 139     <ol>
 140       <li><tt>cd <i>where-you-want-llvm-to-live</i></tt>
 141       <li><tt>cd llvm/projects</tt>
 142       <li><tt>gunzip --stdout llvm-test-<i>version</i>.tar.gz | tar -xvf -</tt>
 143     </ol></li>
 144
 145   </ul></li>
 146
 147
 148   <li>Configure the LLVM Build Environment
 149   <ol>
 150     <li><tt>cd <i>where-you-want-to-build-llvm</i></tt></li>
 151     <li><tt><i>/path/to/llvm/</i>configure [options]</tt><br>
 152     Some common options:
 153
 154       <ul>
 155         <li><tt>--prefix=<i>directory</i></tt>
 156         <p>Specify for <i>directory</i> the full pathname of where you
 157         want the LLVM tools and libraries to be installed (default
 158         <tt>/usr/local</tt>).</p></li>
 159         <li><tt>--with-llvmgccdir=<i>directory</i></tt>
 160         <p>Optionally, specify for <i>directory</i> the full pathname of the
 161         C/C++ front end installation to use with this LLVM configuration. If
 162         not specified, the PATH will be searched.  This is only needed if you
 163         want to run the testsuite or do some special kinds of LLVM builds.</p></li>
 164         <li><tt>--enable-spec2000=<i>directory</i></tt>
 165             <p>Enable the SPEC2000 benchmarks for testing.  The SPEC2000
 166             benchmarks should be available in
 167             <tt><i>directory</i></tt>.</p></li>
 168       </ul>
 169   </ol></li>
 170
 171   <li>Build the LLVM Suite:
 172   <ol>
 173       <li><tt>gmake -k |&amp; tee gnumake.out
 174       &nbsp;&nbsp;&nbsp;# this is csh or tcsh syntax</tt></li>
 175       <li>If you get an "internal compiler error (ICE)" or test failures, see
 176           <a href="#brokengcc">below</a>.</li>
 177   </ol>
 178
 179 </ol>
 180
 181 <p>Consult the <a href="#starting">Getting Started with LLVM</a> section for
 182 detailed information on configuring and compiling LLVM.  See <a
 183 href="#environment">Setting Up Your Environment</a> for tips that simplify
 184 working with the GCC front end and LLVM tools.  Go to <a href="#layout">Program
 185 Layout</a> to learn about the layout of the source code tree.</p>
 186
 187 </div>
 188
 189 <!-- *********************************************************************** -->
 190 <div class="doc_section">
 191   <a name="requirements"><b>Requirements</b></a>
 192 </div>
 193 <!-- *********************************************************************** -->
 194
 195 <div class="doc_text">
 196
 197 <p>Before you begin to use the LLVM system, review the requirements given below.
 198 This may save you some trouble by knowing ahead of time what hardware and
 199 software you will need.</p>
 200
 201 </div>
 202
 203 <!-- ======================================================================= -->
 204 <div class="doc_subsection">
 205   <a name="hardware"><b>Hardware</b></a>
 206 </div>
 207
 208 <div class="doc_text">
 209
 210 <p>LLVM is known to work on the following platforms:</p>
 211
 212 <table cellpadding="3" summary="Known LLVM platforms">
 213 <tr>
 214   <th>OS</th>
 215   <th>Arch</th>
 216   <th>Compilers</th>
 217 </tr>
 218 <tr>
 219   <td>Linux</td>
 220   <td>x86<sup><a href="#pf_1">1</a></sup></td>
 221   <td>GCC</td>
 222 </tr>
 223 <tr>
 224   <td>Solaris</td>
 225   <td>V9 (Ultrasparc)</td>
 226   <td>GCC</td>
 227 </tr>
 228 <tr>
 229   <td>FreeBSD</td>
 230   <td>x86<sup><a href="#pf_1">1</a></sup></td>
 231   <td>GCC</td>
 232 </tr>
 233 <tr>
 234   <td>MacOS X<sup><a href="#pf_2">2</a></sup></td>
 235   <td>PowerPC</td>
 236   <td>GCC</td>
 237 </tr>
 238 <tr>
 239   <td>MacOS X<sup><a href="#pf_2">2</a>,<a href="#pf_9">9</a></sup></td>
 240   <td>x86</td>
 241   <td>GCC</td>
 242
 243 </tr>
 244 <tr>
 245   <td>Cygwin/Win32</td>
 246   <td>x86<sup><a href="#pf_1">1</a>,<a href="#pf_8">8</a></sup></td>
 247   <td>GCC 3.4.X, binutils 2.15</td>
 248 </tr>
 249 <tr>
 250   <td>MinGW/Win32</td>
 251   <td>x86<sup><a href="#pf_1">1</a>,<a href="#pf_6">6</a>,<a href="#pf_8">8</a></sup></td>
 252   <td>GCC 3.4.X, binutils 2.15</td>
 253 </tr>
 254 <tr>
 255   <td>Linux</td>
 256   <td>amd64</td>
 257   <td>GCC</td>
 258 </tr>
 259 </table>
 260
 261 <p>LLVM has partial support for the following platforms:</p>
 262
 263 <table summary="LLVM partial platform support">
 264 <tr>
 265   <th>OS</th>
 266   <th>Arch</th>
 267   <th>Compilers</th>
 268 </tr>
 269 <tr>
 270   <td>Windows</td>
 271   <td>x86<sup><a href="#pf_1">1</a></sup></td>
 272   <td>Visual Studio 2005 SP1 or higher<sup><a href="#pf_4">4</a>,<a href="#pf_5">5</a></sup></td>
 273 <tr>
 274   <td>AIX<sup><a href="#pf_3">3</a>,<a href="#pf_4">4</a></sup></td>
 275   <td>PowerPC</td>
 276   <td>GCC</td>
 277 </tr>
 278 <tr>
 279   <td>Linux<sup><a href="#pf_3">3</a>,<a href="#pf_5">5</a></sup></td>
 280   <td>PowerPC</td>
 281   <td>GCC</td>
 282 </tr>
 283
 284 <tr>
 285   <td>Linux<sup><a href="#pf_7">7</a></sup></td>
 286   <td>Alpha</td>
 287   <td>GCC</td>
 288 </tr>
 289 <tr>
 290   <td>Linux<sup><a href="#pf_7">7</a></sup></td>
 291   <td>Itanium (IA-64)</td>
 292   <td>GCC</td>
 293 </tr>
 294 <tr>
 295   <td>HP-UX<sup><a href="#pf_7">7</a></sup></td>
 296   <td>Itanium (IA-64)</td>
 297   <td>HP aCC</td>
 298 </tr>
 299 </table>
 300
 301 <p><b>Notes:</b></p>
 302
 303 <div class="doc_notes">
 304 <ol>
 305 <li><a name="pf_1">Code generation supported for Pentium processors and
 306 up</a></li>
 307 <li><a name="pf_2">Code generation supported for 32-bit ABI only</a></li>
 308 <li><a name="pf_3">No native code generation</a></li>
 309 <li><a name="pf_4">Build is not complete: one or more tools do not link or function</a></li>
 310 <li><a name="pf_5">The GCC-based C/C++ frontend does not build</a></li>
 311 <li><a name="pf_6">The port is done using the MSYS shell.</a></li>
 312 <li><a name="pf_7">Native code generation exists but is not complete.</a></li>
 313 <li><a name="pf_8">Binutils</a> up to post-2.17 has bug in bfd/cofflink.c
 314     preventing LLVM from building correctly. Several workarounds have been
 315     introduced into LLVM build system, but the bug can occur anytime in the
 316     future. We highly recommend that you rebuild your current binutils with the
 317     patch from <a href="http://sourceware.org/bugzilla/show_bug.cgi?id=2659">
 318     Binutils bugzilla</a>, if it wasn't already applied.</li>
 319 <li><a name="pf_9">XCode 2.5 and gcc 4.0.1</a> (Apple Build 5370) will trip
 320     internal LLVM assert messages when compiled for Release at optimization
 321     levels greater than 0 (i.e., <i>"-O1"</i> and higher).
 322     Add <i>OPTIMIZE_OPTION="-O0"</i> to the build command line
 323     if compiling for LLVM Release or bootstrapping the LLVM toolchain.</li>
 324 </ol>
 325 </div>
 326
 327 <p>Note that you will need about 1-3 GB of space for a full LLVM build in Debug
 328 mode, depending on the system (it is so large because of all the debugging
 329 information and the fact that the libraries are statically linked into multiple
 330 tools).  If you do not need many of the tools and you are space-conscious, you
 331 can pass <tt>ONLY_TOOLS="tools you need"</tt> to make.  The Release build
 332 requires considerably less space.</p>
 333
 334 <p>The LLVM suite <i>may</i> compile on other platforms, but it is not
 335 guaranteed to do so.  If compilation is successful, the LLVM utilities should be
 336 able to assemble, disassemble, analyze, and optimize LLVM bitcode.  Code
 337 generation should work as well, although the generated native code may not work
 338 on your platform.</p>
 339
 340 <p>The GCC front end is not very portable at the moment.  If you want to get it
 341 to work on another platform, you can download a copy of the source and <a
 342 href="GCCFEBuildInstrs.html">try to compile it</a> on your platform.</p>
 343
 344 </div>
 345
 346 <!-- ======================================================================= -->
 347 <div class="doc_subsection"><a name="software"><b>Software</b></a></div>
 348 <div class="doc_text">
 349   <p>Compiling LLVM requires that you have several software packages
 350   installed. The table below lists those required packages. The Package column
 351   is the usual name for the software package that LLVM depends on. The Version
 352   column provides "known to work" versions of the package. The Notes column
 353   describes how LLVM uses the package and provides other details.</p>
 354   <table summary="Packages required to compile LLVM">
 355     <tr><th>Package</th><th>Version</th><th>Notes</th></tr>
 356
 357     <tr>
 358       <td><a href="http://savannah.gnu.org/projects/make">GNU Make</a></td>
 359       <td>3.79, 3.79.1</td>
 360       <td>Makefile/build processor</td>
 361     </tr>
 362
 363     <tr>
 364       <td><a href="http://gcc.gnu.org">GCC</a></td>
 365       <td>3.4.2</td>
 366       <td>C/C++ compiler<sup><a href="#sf1">1</a></sup></td>
 367     </tr>
 368
 369     <tr>
 370       <td><a href="http://www.gnu.org/software/texinfo">TeXinfo</a></td>
 371       <td>4.5</td>
 372       <td>For building the CFE</td>
 373     </tr>
 374
 375     <tr>
 376       <td><a href="http://subversion.tigris.org/project_packages.html">SVN</a></td>
 377       <td>&ge;1.3</td>
 378       <td>Subversion access to LLVM<sup><a href="#sf2">2</a></sup></td>
 379     </tr>
 380
 381     <tr>
 382       <td><a href="http://savannah.gnu.org/projects/dejagnu">DejaGnu</a></td>
 383       <td>1.4.2</td>
 384       <td>Automated test suite<sup><a href="#sf3">3</a></sup></td>
 385     </tr>
 386
 387     <tr>
 388       <td><a href="http://www.tcl.tk/software/tcltk/">tcl</a></td>
 389       <td>8.3, 8.4</td>
 390       <td>Automated test suite<sup><a href="#sf3">3</a></sup></td>
 391     </tr>
 392
 393     <tr>
 394       <td><a href="http://expect.nist.gov/">expect</a></td>
 395       <td>5.38.0</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.perl.com/download.csp">perl</a></td>
 401       <td>&ge;5.6.0</td>
 402       <td>Nightly tester, utilities</td>
 403     </tr>
 404
 405     <tr>
 406       <td><a href="http://savannah.gnu.org/projects/m4">GNU M4</a>
 407       <td>1.4</td>
 408       <td>Macro processor for configuration<sup><a href="#sf4">4</a></sup></td>
 409     </tr>
 410
 411     <tr>
 412       <td><a href="http://www.gnu.org/software/autoconf">GNU Autoconf</a></td>
 413       <td>2.59</td>
 414       <td>Configuration script builder<sup><a href="#sf4">4</a></sup></td>
 415     </tr>
 416
 417     <tr>
 418       <td><a href="http://www.gnu.org/software/automake">GNU Automake</a></td>
 419       <td>1.9.2</td>
 420       <td>aclocal macro generator<sup><a href="#sf4">4</a></sup></td>
 421     </tr>
 422
 423     <tr>
 424       <td><a href="http://savannah.gnu.org/projects/libtool">libtool</a></td>
 425       <td>1.5.10</td>
 426       <td>Shared library manager<sup><a href="#sf4">4</a></sup></td>
 427     </tr>
 428
 429   </table>
 430
 431   <p><b>Notes:</b></p>
 432   <div class="doc_notes">
 433   <ol>
 434     <li><a name="sf1">Only the C and C++ languages are needed so there's no
 435       need to build the other languages for LLVM's purposes.</a> See
 436       <a href="#brokengcc">below</a> for specific version info.</li>
 437     <li><a name="sf2">You only need Subversion if you intend to build from the
 438       latest LLVM sources. If you're working from a release distribution, you
 439       don't need Subversion.</a></li>
 440     <li><a name="sf3">Only needed if you want to run the automated test
 441       suite in the <tt>llvm/test</tt> directory.</a></li>
 442     <li><a name="sf4">If you want to make changes to the configure scripts,
 443       you will need GNU autoconf (2.59), and consequently, GNU M4 (version 1.4
 444       or higher). You will also need automake (1.9.2). We only use aclocal
 445       from that package.</a></li>
 446   </ol>
 447   </div>
 448
 449   <p>Additionally, your compilation host is expected to have the usual
 450   plethora of Unix utilities. Specifically:</p>
 451   <ul>
 452     <li><b>ar</b> - archive library builder</li>
 453     <li><b>bzip2*</b> - bzip2 command for distribution generation</li>
 454     <li><b>bunzip2*</b> - bunzip2 command for distribution checking</li>
 455     <li><b>chmod</b> - change permissions on a file</li>
 456     <li><b>cat</b> - output concatenation utility</li>
 457     <li><b>cp</b> - copy files</li>
 458     <li><b>date</b> - print the current date/time </li>
 459     <li><b>echo</b> - print to standard output</li>
 460     <li><b>egrep</b> - extended regular expression search utility</li>
 461     <li><b>find</b> - find files/dirs in a file system</li>
 462     <li><b>grep</b> - regular expression search utility</li>
 463     <li><b>gzip*</b> - gzip command for distribution generation</li>
 464     <li><b>gunzip*</b> - gunzip command for distribution checking</li>
 465     <li><b>install</b> - install directories/files </li>
 466     <li><b>mkdir</b> - create a directory</li>
 467     <li><b>mv</b> - move (rename) files</li>
 468     <li><b>ranlib</b> - symbol table builder for archive libraries</li>
 469     <li><b>rm</b> - remove (delete) files and directories</li>
 470     <li><b>sed</b> - stream editor for transforming output</li>
 471     <li><b>sh</b> - Bourne shell for make build scripts</li>
 472     <li><b>tar</b> - tape archive for distribution generation</li>
 473     <li><b>test</b> - test things in file system</li>
 474     <li><b>unzip*</b> - unzip command for distribution checking</li>
 475     <li><b>zip*</b> - zip command for distribution generation</li>
 476   </ul>
 477 </div>
 478
 479 <!-- ======================================================================= -->
 480 <div class="doc_subsection">
 481   <a name="brokengcc">Broken versions of GCC and other tools</a>
 482 </div>
 483
 484 <div class="doc_text">
 485
 486 <p>LLVM is very demanding of the host C++ compiler, and as such tends to expose
 487 bugs in the compiler.  In particular, several versions of GCC crash when trying
 488 to compile LLVM.  We routinely use GCC 3.3.3, 3.4.0, and Apple 4.0.1
 489 successfully with them (however, see important notes below).  Other versions
 490 of GCC will probably work as well.  GCC versions listed
 491 here are known to not work.  If you are using one of these versions, please try
 492 to upgrade your GCC to something more recent.  If you run into a problem with a
 493 version of GCC not listed here, please <a href="mailto:llvmdev@cs.uiuc.edu">let
 494 us know</a>.  Please use the "<tt>gcc -v</tt>" command to find out which version
 495 of GCC you are using.
 496 </p>
 497
 498 <p><b>GCC versions prior to 3.0</b>: GCC 2.96.x and before had several
 499 problems in the STL that effectively prevent it from compiling LLVM.
 500 </p>
 501
 502 <p><b>GCC 3.2.2 and 3.2.3</b>: These versions of GCC fails to compile LLVM with
 503 a bogus template error.  This was fixed in later GCCs.</p>
 504
 505 <p><b>GCC 3.3.2</b>: This version of GCC suffered from a <a
 506 href="http://gcc.gnu.org/PR13392">serious bug</a> which causes it to crash in
 507 the "<tt>convert_from_eh_region_ranges_1</tt>" GCC function.</p>
 508
 509 <p><b>Cygwin GCC 3.3.3</b>: The version of GCC 3.3.3 commonly shipped with
 510    Cygwin does not work.  Please <a href="GCCFEBuildInstrs.html#cygwin">upgrade
 511    to a newer version</a> if possible.</p>
 512 <p><b>SuSE GCC 3.3.3</b>: The version of GCC 3.3.3 shipped with SuSE 9.1 (and
 513    possibly others) does not compile LLVM correctly (it appears that exception
 514    handling is broken in some cases).  Please download the FSF 3.3.3 or upgrade
 515    to a newer version of GCC.</p>
 516 <p><b>GCC 3.4.0 on linux/x86 (32-bit)</b>: GCC miscompiles portions of the
 517    code generator, causing an infinite loop in the llvm-gcc build when built
 518    with optimizations enabled (i.e. a release build).</p>
 519 <p><b>GCC 3.4.2 on linux/x86 (32-bit)</b>: GCC miscompiles portions of the
 520    code generator at -O3, as with 3.4.0.  However gcc 3.4.2 (unlike 3.4.0)
 521    correctly compiles LLVM at -O2.  A work around is to build release LLVM
 522    builds with "make ENABLE_OPTIMIZED=1 OPTIMIZE_OPTION=-O2 ..."</p>
 523 <p><b>GCC 3.4.x on X86-64/amd64</b>: GCC <a href="http://llvm.org/PR1056">
 524    miscompiles portions of LLVM</a>.</p>
 525 <p><b>GCC 3.4.4 (CodeSourcery ARM 2005q3-2)</b>: this compiler miscompiles LLVM
 526    when building with optimizations enabled.  It appears to work with
 527    "<tt>make ENABLE_OPTIMIZED=1 OPTIMIZE_OPTION=-O1</tt>" or build a debug
 528    build.</p>
 529 <p><b>IA-64 GCC 4.0.0</b>: The IA-64 version of GCC 4.0.0 is known to
 530    miscompile LLVM.</p>
 531 <p><b>Apple Xcode 2.3</b>: GCC crashes when compiling LLVM at -O3 (which is the
 532    default with ENABLE_OPTIMIZED=1.  To work around this, build with
 533    "ENABLE_OPTIMIZED=1 OPTIMIZE_OPTION=-O2".</p>
 534 <p><b>GCC 4.1.1</b>: GCC fails to build LLVM with template concept check errors
 535       compiling some files.  At the time of this writing, GCC mainline (4.2)
 536       did not share the problem.</p>
 537 <p><b>GCC 4.1.1 on X86-64/amd64</b>: GCC <a href="http://llvm.org/PR1063">
 538    miscompiles portions of LLVM</a> when compiling llvm itself into 64-bit
 539    code.  LLVM will appear to mostly work but will be buggy, e.g. failing
 540    portions of its testsuite.</p>
 541 <p><b>GCC 4.1.2 on OpenSUSE</b>: Seg faults during libstdc++ build and on x86_64
 542 platforms compiling md5.c gets a mangled constant.</p>
 543 <p><b>GCC 4.1.2 (20061115 (prerelease) (Debian 4.1.1-21)) on Debian</b>: Appears
 544 to miscompile parts of LLVM 2.4. One symptom is ValueSymbolTable complaining
 545 about symbols remaining in the table on destruction.</p>
 546 <p><b>GCC 4.1.2 20071124 (Red Hat 4.1.2-42)</b>: Suffers from the same symptoms
 547 as the previous one. It appears to work with ENABLE_OPTIMIZED=0 (the default).</p>
 548 <p><b>Cygwin GCC 4.3.2 20080827 (beta) 2</b>:
 549   Users <a href="http://llvm.org/PR4145">reported</a> various problems related
 550   with link errors when using this GCC version.</p>
 551
 552 <p><b>GNU ld 2.16.X</b>. Some 2.16.X versions of the ld linker will produce very
 553 long warning messages complaining that some ".gnu.linkonce.t.*" symbol was
 554 defined in a discarded section. You can safely ignore these messages as they are
 555 erroneous and the linkage is correct.  These messages disappear using ld
 556 2.17.</p>
 557
 558 <p><b>GNU binutils 2.17</b>: Binutils 2.17 contains <a
 559 href="http://sourceware.org/bugzilla/show_bug.cgi?id=3111">a bug</a> which
 560 causes huge link times (minutes instead of seconds) when building LLVM.  We
 561 recommend upgrading to a newer version (2.17.50.0.4 or later).</p>
 562
 563 <p><b>GNU Binutils 2.19.1 Gold</b>: This version of Gold contained
 564 <a href="http://sourceware.org/bugzilla/show_bug.cgi?id=9836">a bug</a>
 565 which causes intermittent failures when building LLVM with position independent
 566 code.  The symptom is an error about cyclic dependencies.  We recommend
 567 upgrading to a newer version of Gold.</p>
 568
 569 </div>
 570
 571
 572
 573 <!-- *********************************************************************** -->
 574 <div class="doc_section">
 575   <a name="starting"><b>Getting Started with LLVM</b></a>
 576 </div>
 577 <!-- *********************************************************************** -->
 578
 579 <div class="doc_text">
 580
 581 <p>The remainder of this guide is meant to get you up and running with
 582 LLVM and to give you some basic information about the LLVM environment.</p>
 583
 584 <p>The later sections of this guide describe the <a
 585 href="#layout">general layout</a> of the the LLVM source tree, a <a
 586 href="#tutorial">simple example</a> using the LLVM tool chain, and <a
 587 href="#links">links</a> to find more information about LLVM or to get
 588 help via e-mail.</p>
 589 </div>
 590
 591 <!-- ======================================================================= -->
 592 <div class="doc_subsection">
 593   <a name="terminology">Terminology and Notation</a>
 594 </div>
 595
 596 <div class="doc_text">
 597
 598 <p>Throughout this manual, the following names are used to denote paths
 599 specific to the local system and working environment.  <i>These are not
 600 environment variables you need to set but just strings used in the rest
 601 of this document below</i>.  In any of the examples below, simply replace
 602 each of these names with the appropriate pathname on your local system.
 603 All these paths are absolute:</p>
 604
 605 <dl>
 606     <dt>SRC_ROOT
 607     <dd>
 608     This is the top level directory of the LLVM source tree.
 609     <br><br>
 610
 611     <dt>OBJ_ROOT
 612     <dd>
 613     This is the top level directory of the LLVM object tree (i.e. the
 614     tree where object files and compiled programs will be placed.  It
 615     can be the same as SRC_ROOT).
 616     <br><br>
 617
 618     <dt>LLVMGCCDIR
 619     <dd>
 620     This is where the LLVM GCC Front End is installed.
 621     <p>
 622     For the pre-built GCC front end binaries, the LLVMGCCDIR is
 623     <tt>llvm-gcc/<i>platform</i>/llvm-gcc</tt>.
 624 </dl>
 625
 626 </div>
 627
 628 <!-- ======================================================================= -->
 629 <div class="doc_subsection">
 630   <a name="environment">Setting Up Your Environment</a>
 631 </div>
 632
 633 <div class="doc_text">
 634
 635 <p>
 636 In order to compile and use LLVM, you may need to set some environment
 637 variables.
 638
 639 <dl>
 640   <dt><tt>LLVM_LIB_SEARCH_PATH</tt>=<tt>/path/to/your/bitcode/libs</tt></dt>
 641   <dd>[Optional] This environment variable helps LLVM linking tools find the
 642   locations of your bitcode libraries. It is provided only as a
 643   convenience since you can specify the paths using the -L options of the
 644   tools and the C/C++ front-end will automatically use the bitcode files
 645   installed in its
 646   <tt>lib</tt> directory.</dd>
 647 </dl>
 648
 649 </div>
 650
 651 <!-- ======================================================================= -->
 652 <div class="doc_subsection">
 653   <a name="unpack">Unpacking the LLVM Archives</a>
 654 </div>
 655
 656 <div class="doc_text">
 657
 658 <p>
 659 If you have the LLVM distribution, you will need to unpack it before you
 660 can begin to compile it.  LLVM is distributed as a set of two files: the LLVM
 661 suite and the LLVM GCC front end compiled for your platform.  There is an
 662 additional test suite that is optional.  Each file is a TAR archive that is
 663 compressed with the gzip program.
 664 </p>
 665
 666 <p>The files are as follows, with <em>x.y</em> marking the version number:
 667 <dl>
 668   <dt><tt>llvm-x.y.tar.gz</tt></dt>
 669   <dd>Source release for the LLVM libraries and tools.<br></dd>
 670
 671   <dt><tt>llvm-test-x.y.tar.gz</tt></dt>
 672   <dd>Source release for the LLVM test suite.</dd>
 673
 674   <dt><tt>llvm-gcc-4.2-x.y.source.tar.gz</tt></dt>
 675   <dd>Source release of the llvm-gcc-4.2 front end.  See README.LLVM in the root
 676       directory for build instructions.<br></dd>
 677
 678   <dt><tt>llvm-gcc-4.2-x.y-platform.tar.gz</tt></dt>
 679   <dd>Binary release of the llvm-gcc-4.2 front end for a specific platform.<br></dd>
 680
 681 </dl>
 682
 683 </div>
 684
 685 <!-- ======================================================================= -->
 686 <div class="doc_subsection">
 687   <a name="checkout">Checkout LLVM from Subversion</a>
 688 </div>
 689
 690 <div class="doc_text">
 691
 692 <p>If you have access to our Subversion repository, you can get a fresh copy of
 693 the entire source code.  All you need to do is check it out from Subversion as
 694 follows:</p>
 695
 696 <ul>
 697   <li><tt>cd <i>where-you-want-llvm-to-live</i></tt></li>
 698   <li>Read-Only: <tt>svn co http://llvm.org/svn/llvm-project/llvm/trunk llvm</tt></li>
 699   <li>Read-Write:<tt>svn co https://user@llvm.org/svn/llvm-project/llvm/trunk
 700     llvm</tt></li>
 701 </ul>
 702
 703
 704 <p>This will create an '<tt>llvm</tt>' directory in the current
 705 directory and fully populate it with the LLVM source code, Makefiles,
 706 test directories, and local copies of documentation files.</p>
 707
 708 <p>If you want to get a specific release (as opposed to the most recent
 709 revision), you can checkout it from the '<tt>tags</tt>' directory (instead of
 710 '<tt>trunk</tt>'). The following releases are located in the following
 711 subdirectories of the '<tt>tags</tt>' directory:</p>
 712
 713 <ul>
 714 <li>Release 2.5: <b>RELEASE_25</b></li>
 715 <li>Release 2.4: <b>RELEASE_24</b></li>
 716 <li>Release 2.3: <b>RELEASE_23</b></li>
 717 <li>Release 2.2: <b>RELEASE_22</b></li>
 718 <li>Release 2.1: <b>RELEASE_21</b></li>
 719 <li>Release 2.0: <b>RELEASE_20</b></li>
 720 <li>Release 1.9: <b>RELEASE_19</b></li>
 721 <li>Release 1.8: <b>RELEASE_18</b></li>
 722 <li>Release 1.7: <b>RELEASE_17</b></li>
 723 <li>Release 1.6: <b>RELEASE_16</b></li>
 724 <li>Release 1.5: <b>RELEASE_15</b></li>
 725 <li>Release 1.4: <b>RELEASE_14</b></li>
 726 <li>Release 1.3: <b>RELEASE_13</b></li>
 727 <li>Release 1.2: <b>RELEASE_12</b></li>
 728 <li>Release 1.1: <b>RELEASE_11</b></li>
 729 <li>Release 1.0: <b>RELEASE_1</b></li>
 730 </ul>
 731
 732 <p>If you would like to get the LLVM test suite (a separate package as of 1.4),
 733 you get it from the Subversion repository:</p>
 734
 735 <div class="doc_code">
 736 <pre>
 737 % cd llvm/projects
 738 % svn co http://llvm.org/svn/llvm-project/test-suite/trunk llvm-test
 739 </pre>
 740 </div>
 741
 742 <p>By placing it in the <tt>llvm/projects</tt>, it will be automatically
 743 configured by the LLVM configure script as well as automatically updated when
 744 you run <tt>svn update</tt>.</p>
 745
 746 <p>If you would like to get the GCC front end source code, you can also get it
 747 and build it yourself.  Please follow <a href="GCCFEBuildInstrs.html">these
 748 instructions</a> to successfully get and build the LLVM GCC front-end.</p>
 749
 750 </div>
 751
 752 <!-- ======================================================================= -->
 753 <div class="doc_subsection">
 754   <a name="installcf">Install the GCC Front End</a>
 755 </div>
 756
 757 <div class="doc_text">
 758
 759 <p>Before configuring and compiling the LLVM suite, you can optionally extract the
 760 LLVM GCC front end from the binary distribution.  It is used for running the
 761 llvm-test testsuite and for compiling C/C++ programs.  Note that you can optionally
 762 <a href="GCCFEBuildInstrs.html">build llvm-gcc yourself</a> after building the
 763 main LLVM repository.</p>
 764
 765 <p>To install the GCC front end, do the following:</p>
 766
 767 <ol>
 768   <li><tt>cd <i>where-you-want-the-front-end-to-live</i></tt></li>
 769   <li><tt>gunzip --stdout llvm-gcc-4.2-<i>version</i>-<i>platform</i>.tar.gz | tar -xvf
 770       -</tt></li>
 771 </ol>
 772
 773 <p>Once the binary is uncompressed, you should add a symlink for llvm-gcc and
 774 llvm-g++ to some directory in your path.  When you configure LLVM, it will
 775 automatically detect llvm-gcc's presence (if it is in your path) enabling its
 776 use in llvm-test.  Note that you can always build or install llvm-gcc at any
 777 pointer after building the main LLVM repository: just reconfigure llvm and
 778 llvm-test will pick it up.
 779 </p>
 780
 781 <p>The binary versions of the GCC front end may not suit all of your needs.  For
 782 example, the binary distribution may include an old version of a system header
 783 file, not "fix" a header file that needs to be fixed for GCC, or it may be
 784 linked with libraries not available on your system.</p>
 785
 786 <p>In cases like these, you may want to try <a
 787 href="GCCFEBuildInstrs.html">building the GCC front end from source.</a> This is
 788 much easier now than it was in the past.</p>
 789
 790 </div>
 791
 792 <!-- ======================================================================= -->
 793 <div class="doc_subsection">
 794   <a name="config">Local LLVM Configuration</a>
 795 </div>
 796
 797 <div class="doc_text">
 798
 799   <p>Once checked out from the Subversion repository, the LLVM suite source
 800   code must be
 801 configured via the <tt>configure</tt> script.  This script sets variables in the
 802 various <tt>*.in</tt> files, most notably <tt>llvm/Makefile.config</tt> and
 803 <tt>llvm/include/Config/config.h</tt>.  It also populates <i>OBJ_ROOT</i> with
 804 the Makefiles needed to begin building LLVM.</p>
 805
 806 <p>The following environment variables are used by the <tt>configure</tt>
 807 script to configure the build system:</p>
 808
 809 <table summary="LLVM configure script environment variables">
 810   <tr><th>Variable</th><th>Purpose</th></tr>
 811   <tr>
 812     <td>CC</td>
 813     <td>Tells <tt>configure</tt> which C compiler to use.  By default,
 814         <tt>configure</tt> will look for the first GCC C compiler in
 815         <tt>PATH</tt>.  Use this variable to override
 816         <tt>configure</tt>'s default behavior.</td>
 817   </tr>
 818   <tr>
 819     <td>CXX</td>
 820     <td>Tells <tt>configure</tt> which C++ compiler to use.  By default,
 821        <tt>configure</tt> will look for the first GCC C++ compiler in
 822        <tt>PATH</tt>.  Use this variable to override
 823        <tt>configure</tt>'s default behavior.</td>
 824   </tr>
 825 </table>
 826
 827 <p>The following options can be used to set or enable LLVM specific options:</p>
 828
 829 <dl>
 830   <dt><i>--with-llvmgccdir</i></dt>
 831   <dd>Path to the LLVM C/C++ FrontEnd to be used with this LLVM configuration.
 832   The value of this option should specify the full pathname of the C/C++ Front
 833   End to be used. If this option is not provided, the PATH will be searched for
 834   a program named <i>llvm-gcc</i> and the C/C++ FrontEnd install directory will
 835   be inferred from the path found. If the option is not given, and no llvm-gcc
 836   can be found in the path then a warning will be produced by
 837   <tt>configure</tt> indicating this situation. LLVM may still be built with
 838   the <tt>tools-only</tt> target but attempting to build the runtime libraries
 839   will fail as these libraries require llvm-gcc and llvm-g++. See
 840   <a href="#installcf">Install the GCC Front End</a> for details on installing
 841   the C/C++ Front End. See
 842   <a href="GCCFEBuildInstrs.html">Bootstrapping the LLVM C/C++ Front-End</a>
 843   for details on building the C/C++ Front End.</dd>
 844   <dt><i>--with-tclinclude</i></dt>
 845   <dd>Path to the tcl include directory under which <tt>tclsh</tt> can be
 846   found. Use this if you have multiple tcl installations on your machine and you
 847   want to use a specific one (8.x) for LLVM. LLVM only uses tcl for running the
 848   dejagnu based test suite in <tt>llvm/test</tt>. If you don't specify this
 849   option, the LLVM configure script will search for the tcl 8.4 and 8.3
 850   releases.
 851   <br><br>
 852   </dd>
 853   <dt><i>--enable-optimized</i></dt>
 854   <dd>
 855     Enables optimized compilation (debugging symbols are removed
 856     and GCC optimization flags are enabled). Note that this is the default
 857     setting     if you are using the LLVM distribution. The default behavior
 858     of an Subversion checkout is to use an unoptimized build (also known as a
 859     debug build).
 860     <br><br>
 861   </dd>
 862   <dt><i>--enable-debug-runtime</i></dt>
 863   <dd>
 864     Enables debug symbols in the runtime libraries. The default is to strip
 865     debug symbols from the runtime libraries.
 866   </dd>
 867   <dt><i>--enable-jit</i></dt>
 868   <dd>
 869     Compile the Just In Time (JIT) compiler functionality.  This is not
 870     available
 871     on all platforms.  The default is dependent on platform, so it is best
 872     to explicitly enable it if you want it.
 873     <br><br>
 874   </dd>
 875   <dt><i>--enable-targets=</i><tt>target-option</tt></dt>
 876   <dd>Controls which targets will be built and linked into llc. The default
 877   value for <tt>target_options</tt> is "all" which builds and links all
 878   available targets.  The value "host-only" can be specified to build only a
 879   native compiler (no cross-compiler targets available). The "native" target is
 880   selected as the target of the build host. You can also specify a comma
 881   separated list of target names that you want available in llc. The target
 882   names use all lower case. The current set of targets is: <br>
 883   <tt>alpha, ia64, powerpc, skeleton, sparc, x86</tt>.
 884   <br><br></dd>
 885   <dt><i>--enable-doxygen</i></dt>
 886   <dd>Look for the doxygen program and enable construction of doxygen based
 887   documentation from the source code. This is disabled by default because
 888   generating the documentation can take a long time and producess 100s of
 889   megabytes of output.</dd>
 890   <dt><i>--with-udis86</i></dt>
 891   <dd>LLVM can use external disassembler library for various purposes (now it's
 892   used only for examining code produced by JIT). This option will enable usage
 893   of <a href="http://udis86.sourceforge.net/">udis86</a> x86 (both 32 and 64
 894   bits) disassembler library.</dd>
 895 </dl>
 896
 897 <p>To configure LLVM, follow these steps:</p>
 898
 899 <ol>
 900     <li><p>Change directory into the object root directory:</p>
 901
 902     <div class="doc_code"><pre>% cd <i>OBJ_ROOT</i></pre></div></li>
 903
 904     <li><p>Run the <tt>configure</tt> script located in the LLVM source
 905     tree:</p>
 906
 907     <div class="doc_code">
 908     <pre>% <i>SRC_ROOT</i>/configure --prefix=/install/path [other options]</pre>
 909     </div></li>
 910 </ol>
 911
 912 </div>
 913
 914 <!-- ======================================================================= -->
 915 <div class="doc_subsection">
 916   <a name="compile">Compiling the LLVM Suite Source Code</a>
 917 </div>
 918
 919 <div class="doc_text">
 920
 921 <p>Once you have configured LLVM, you can build it.  There are three types of
 922 builds:</p>
 923
 924 <dl>
 925     <dt>Debug Builds
 926     <dd>
 927     These builds are the default when one is using an Subversion checkout and
 928     types <tt>gmake</tt> (unless the <tt>--enable-optimized</tt> option was
 929     used during configuration).  The build system will compile the tools and
 930     libraries with debugging information.  To get a Debug Build using the
 931     LLVM distribution the <tt>--disable-optimized</tt> option must be passed
 932     to <tt>configure</tt>.
 933     <br><br>
 934
 935     <dt>Release (Optimized) Builds
 936     <dd>
 937     These builds are enabled with the <tt>--enable-optimized</tt> option to
 938     <tt>configure</tt> or by specifying <tt>ENABLE_OPTIMIZED=1</tt> on the
 939     <tt>gmake</tt> command line.  For these builds, the build system will
 940     compile the tools and libraries with GCC optimizations enabled and strip
 941     debugging information from the libraries and executables it generates.
 942     Note that Release Builds are default when using an LLVM distribution.
 943     <br><br>
 944
 945     <dt>Profile Builds
 946     <dd>
 947     These builds are for use with profiling.  They compile profiling
 948     information into the code for use with programs like <tt>gprof</tt>.
 949     Profile builds must be started by specifying <tt>ENABLE_PROFILING=1</tt>
 950     on the <tt>gmake</tt> command line.
 951 </dl>
 952
 953 <p>Once you have LLVM configured, you can build it by entering the
 954 <i>OBJ_ROOT</i> directory and issuing the following command:</p>
 955
 956 <div class="doc_code"><pre>% gmake</pre></div>
 957
 958 <p>If the build fails, please <a href="#brokengcc">check here</a> to see if you
 959 are using a version of GCC that is known not to compile LLVM.</p>
 960
 961 <p>
 962 If you have multiple processors in your machine, you may wish to use some of
 963 the parallel build options provided by GNU Make.  For example, you could use the
 964 command:</p>
 965
 966 <div class="doc_code"><pre>% gmake -j2</pre></div>
 967
 968 <p>There are several special targets which are useful when working with the LLVM
 969 source code:</p>
 970
 971 <dl>
 972   <dt><tt>gmake clean</tt>
 973   <dd>
 974   Removes all files generated by the build.  This includes object files,
 975   generated C/C++ files, libraries, and executables.
 976   <br><br>
 977
 978   <dt><tt>gmake dist-clean</tt>
 979   <dd>
 980   Removes everything that <tt>gmake clean</tt> does, but also removes files
 981   generated by <tt>configure</tt>.  It attempts to return the source tree to the
 982   original state in which it was shipped.
 983   <br><br>
 984
 985   <dt><tt>gmake install</tt>
 986   <dd>
 987   Installs LLVM header files, libraries, tools, and documentation in a
 988   hierarchy
 989   under $PREFIX, specified with <tt>./configure --prefix=[dir]</tt>, which
 990   defaults to <tt>/usr/local</tt>.
 991   <br><br>
 992
 993   <dt><tt>gmake -C runtime install-bytecode</tt>
 994   <dd>
 995   Assuming you built LLVM into $OBJDIR, when this command is run, it will
 996   install bitcode libraries into the GCC front end's bitcode library
 997   directory.  If you need to update your bitcode libraries,
 998   this is the target to use once you've built them.
 999   <br><br>
1000 </dl>
1001
1002 <p>Please see the <a href="MakefileGuide.html">Makefile Guide</a> for further
1003 details on these <tt>make</tt> targets and descriptions of other targets
1004 available.</p>
1005
1006 <p>It is also possible to override default values from <tt>configure</tt> by
1007 declaring variables on the command line.  The following are some examples:</p>
1008
1009 <dl>
1010   <dt><tt>gmake ENABLE_OPTIMIZED=1</tt>
1011   <dd>
1012   Perform a Release (Optimized) build.
1013   <br><br>
1014
1015   <dt><tt>gmake ENABLE_OPTIMIZED=1 DISABLE_ASSERTIONS=1</tt>
1016   <dd>
1017   Perform a Release (Optimized) build without assertions enabled.
1018   <br><br>
1019
1020   <dt><tt>gmake ENABLE_OPTIMIZED=0</tt>
1021   <dd>
1022   Perform a Debug build.
1023   <br><br>
1024
1025   <dt><tt>gmake ENABLE_PROFILING=1</tt>
1026   <dd>
1027   Perform a Profiling build.
1028   <br><br>
1029
1030   <dt><tt>gmake VERBOSE=1</tt>
1031   <dd>
1032   Print what <tt>gmake</tt> is doing on standard output.
1033   <br><br>
1034
1035   <dt><tt>gmake TOOL_VERBOSE=1</tt></dt>
1036   <dd>Ask each tool invoked by the makefiles to print out what it is doing on
1037   the standard output. This also implies <tt>VERBOSE=1</tt>.
1038   <br><br></dd>
1039 </dl>
1040
1041 <p>Every directory in the LLVM object tree includes a <tt>Makefile</tt> to build
1042 it and any subdirectories that it contains.  Entering any directory inside the
1043 LLVM object tree and typing <tt>gmake</tt> should rebuild anything in or below
1044 that directory that is out of date.</p>
1045
1046 </div>
1047
1048 <!-- ======================================================================= -->
1049 <div class="doc_subsection">
1050   <a name="cross-compile">Cross-Compiling LLVM</a>
1051 </div>
1052
1053 <div class="doc_text">
1054   <p>It is possible to cross-compile LLVM itself. That is, you can create LLVM
1055   executables and libraries to be hosted on a platform different from the
1056   platform where they are build (a Canadian Cross build). To configure a
1057   cross-compile, supply the configure script with <tt>--build</tt> and
1058   <tt>--host</tt> options that are different. The values of these options must
1059   be legal target triples that your GCC compiler supports.</p>
1060
1061   <p>The result of such a build is executables that are not runnable on
1062   on the build host (--build option) but can be executed on the compile host
1063   (--host option).</p>
1064 </div>
1065
1066 <!-- ======================================================================= -->
1067 <div class="doc_subsection">
1068   <a name="objfiles">The Location of LLVM Object Files</a>
1069 </div>
1070
1071 <div class="doc_text">
1072
1073 <p>The LLVM build system is capable of sharing a single LLVM source tree among
1074 several LLVM builds.  Hence, it is possible to build LLVM for several different
1075 platforms or configurations using the same source tree.</p>
1076
1077 <p>This is accomplished in the typical autoconf manner:</p>
1078
1079 <ul>
1080   <li><p>Change directory to where the LLVM object files should live:</p>
1081
1082       <div class="doc_code"><pre>% cd <i>OBJ_ROOT</i></pre></div></li>
1083
1084   <li><p>Run the <tt>configure</tt> script found in the LLVM source
1085       directory:</p>
1086
1087       <div class="doc_code"><pre>% <i>SRC_ROOT</i>/configure</pre></div></li>
1088 </ul>
1089
1090 <p>The LLVM build will place files underneath <i>OBJ_ROOT</i> in directories
1091 named after the build type:</p>
1092
1093 <dl>
1094   <dt>Debug Builds
1095   <dd>
1096   <dl>
1097     <dt>Tools
1098     <dd><tt><i>OBJ_ROOT</i>/Debug/bin</tt>
1099     <dt>Libraries
1100     <dd><tt><i>OBJ_ROOT</i>/Debug/lib</tt>
1101   </dl>
1102   <br><br>
1103
1104   <dt>Release Builds
1105   <dd>
1106   <dl>
1107     <dt>Tools
1108     <dd><tt><i>OBJ_ROOT</i>/Release/bin</tt>
1109     <dt>Libraries
1110     <dd><tt><i>OBJ_ROOT</i>/Release/lib</tt>
1111   </dl>
1112   <br><br>
1113
1114   <dt>Profile Builds
1115   <dd>
1116   <dl>
1117     <dt>Tools
1118     <dd><tt><i>OBJ_ROOT</i>/Profile/bin</tt>
1119     <dt>Libraries
1120     <dd><tt><i>OBJ_ROOT</i>/Profile/lib</tt>
1121   </dl>
1122 </dl>
1123
1124 </div>
1125
1126 <!-- ======================================================================= -->
1127 <div class="doc_subsection">
1128   <a name="optionalconfig">Optional Configuration Items</a>
1129 </div>
1130
1131 <div class="doc_text">
1132
1133 <p>
1134 If you're running on a Linux system that supports the "<a
1135 href="http://www.tat.physik.uni-tuebingen.de/~rguenth/linux/binfmt_misc.html">binfmt_misc</a>"
1136 module, and you have root access on the system, you can set your system up to
1137 execute LLVM bitcode files directly. To do this, use commands like this (the
1138 first command may not be required if you are already using the module):</p>
1139
1140 <div class="doc_code">
1141 <pre>
1142 $ mount -t binfmt_misc none /proc/sys/fs/binfmt_misc
1143 $ echo ':llvm:M::llvm::/path/to/lli:' &gt; /proc/sys/fs/binfmt_misc/register
1144 $ chmod u+x hello.bc   (if needed)
1145 $ ./hello.bc
1146 </pre>
1147 </div>
1148
1149 <p>
1150 This allows you to execute LLVM bitcode files directly.  Thanks to Jack
1151 Cummings for pointing this out!
1152 </p>
1153
1154 </div>
1155
1156
1157 <!-- *********************************************************************** -->
1158 <div class="doc_section">
1159   <a name="layout"><b>Program Layout</b></a>
1160 </div>
1161 <!-- *********************************************************************** -->
1162
1163 <div class="doc_text">
1164
1165 <p>One useful source of information about the LLVM source base is the LLVM <a
1166 href="http://www.doxygen.org">doxygen</a> documentation available at <tt><a
1167 href="http://llvm.org/doxygen/">http://llvm.org/doxygen/</a></tt>.
1168 The following is a brief introduction to code layout:</p>
1169
1170 </div>
1171
1172 <!-- ======================================================================= -->
1173 <div class="doc_subsection"><a name="examples"><tt>llvm/examples</tt></a></div>
1174 <div class="doc_text">
1175   <p>This directory contains some simple examples of how to use the LLVM IR and
1176   JIT.</p>
1177 </div>
1178
1179 <!-- ======================================================================= -->
1180 <div class="doc_subsection"><a name="include"><tt>llvm/include</tt></a></div>
1181 <div class="doc_text">
1182
1183 <p>This directory contains public header files exported from the LLVM
1184 library. The three main subdirectories of this directory are:</p>
1185
1186 <dl>
1187   <dt><tt><b>llvm/include/llvm</b></tt></dt>
1188   <dd>This directory contains all of the LLVM specific header files.  This
1189   directory also has subdirectories for different portions of LLVM:
1190   <tt>Analysis</tt>, <tt>CodeGen</tt>, <tt>Target</tt>, <tt>Transforms</tt>,
1191   etc...</dd>
1192
1193   <dt><tt><b>llvm/include/llvm/Support</b></tt></dt>
1194   <dd>This directory contains generic support libraries that are provided with
1195   LLVM but not necessarily specific to LLVM. For example, some C++ STL utilities
1196   and a Command Line option processing library store their header files here.
1197   </dd>
1198
1199   <dt><tt><b>llvm/include/llvm/Config</b></tt></dt>
1200   <dd>This directory contains header files configured by the <tt>configure</tt>
1201   script.  They wrap "standard" UNIX and C header files.  Source code can
1202   include these header files which automatically take care of the conditional
1203   #includes that the <tt>configure</tt> script generates.</dd>
1204 </dl>
1205 </div>
1206
1207 <!-- ======================================================================= -->
1208 <div class="doc_subsection"><a name="lib"><tt>llvm/lib</tt></a></div>
1209 <div class="doc_text">
1210
1211 <p>This directory contains most of the source files of the LLVM system. In LLVM,
1212 almost all code exists in libraries, making it very easy to share code among the
1213 different <a href="#tools">tools</a>.</p>
1214
1215 <dl>
1216   <dt><tt><b>llvm/lib/VMCore/</b></tt></dt>
1217   <dd> This directory holds the core LLVM source files that implement core
1218   classes like Instruction and BasicBlock.</dd>
1219
1220   <dt><tt><b>llvm/lib/AsmParser/</b></tt></dt>
1221   <dd>This directory holds the source code for the LLVM assembly language parser
1222   library.</dd>
1223
1224   <dt><tt><b>llvm/lib/BitCode/</b></tt></dt>
1225   <dd>This directory holds code for reading and write LLVM bitcode.</dd>
1226
1227   <dt><tt><b>llvm/lib/Analysis/</b></tt><dd>This directory contains a variety of
1228   different program analyses, such as Dominator Information, Call Graphs,
1229   Induction Variables, Interval Identification, Natural Loop Identification,
1230   etc.</dd>
1231
1232   <dt><tt><b>llvm/lib/Transforms/</b></tt></dt>
1233   <dd> This directory contains the source code for the LLVM to LLVM program
1234   transformations, such as Aggressive Dead Code Elimination, Sparse Conditional
1235   Constant Propagation, Inlining, Loop Invariant Code Motion, Dead Global
1236   Elimination, and many others.</dd>
1237
1238   <dt><tt><b>llvm/lib/Target/</b></tt></dt>
1239   <dd> This directory contains files that describe various target architectures
1240   for code generation.  For example, the <tt>llvm/lib/Target/X86</tt>
1241   directory holds the X86 machine description while
1242   <tt>llvm/lib/Target/CBackend</tt> implements the LLVM-to-C converter.</dd>
1243
1244   <dt><tt><b>llvm/lib/CodeGen/</b></tt></dt>
1245   <dd> This directory contains the major parts of the code generator: Instruction
1246   Selector, Instruction Scheduling, and Register Allocation.</dd>
1247
1248   <dt><tt><b>llvm/lib/Debugger/</b></tt></dt>
1249   <dd> This directory contains the source level debugger library that makes
1250   it possible to instrument LLVM programs so that a debugger could identify
1251   source code locations at which the program is executing.</dd>
1252
1253   <dt><tt><b>llvm/lib/ExecutionEngine/</b></tt></dt>
1254   <dd> This directory contains libraries for executing LLVM bitcode directly
1255   at runtime in both interpreted and JIT compiled fashions.</dd>
1256
1257   <dt><tt><b>llvm/lib/Support/</b></tt></dt>
1258   <dd> This directory contains the source code that corresponds to the header
1259   files located in <tt>llvm/include/Support/</tt>.</dd>
1260
1261   <dt><tt><b>llvm/lib/System/</b></tt></dt>
1262   <dd>This directory contains the operating system abstraction layer that
1263   shields LLVM from platform-specific coding.</dd>
1264 </dl>
1265
1266 </div>
1267
1268 <!-- ======================================================================= -->
1269 <div class="doc_subsection"><a name="projects"><tt>llvm/projects</tt></a></div>
1270 <div class="doc_text">
1271   <p>This directory contains projects that are not strictly part of LLVM but are
1272   shipped with LLVM. This is also the directory where you should create your own
1273   LLVM-based projects. See <tt>llvm/projects/sample</tt> for an example of how
1274   to set up your own project.</p>
1275 </div>
1276
1277 <!-- ======================================================================= -->
1278 <div class="doc_subsection"><a name="runtime"><tt>llvm/runtime</tt></a></div>
1279 <div class="doc_text">
1280
1281 <p>This directory contains libraries which are compiled into LLVM bitcode and
1282 used when linking programs with the GCC front end.  Most of these libraries are
1283 skeleton versions of real libraries; for example, libc is a stripped down
1284 version of glibc.</p>
1285
1286 <p>Unlike the rest of the LLVM suite, this directory needs the LLVM GCC front
1287 end to compile.</p>
1288
1289 </div>
1290
1291 <!-- ======================================================================= -->
1292 <div class="doc_subsection"><a name="test"><tt>llvm/test</tt></a></div>
1293 <div class="doc_text">
1294   <p>This directory contains feature and regression tests and other basic sanity
1295   checks on the LLVM infrastructure. These are intended to run quickly and cover
1296   a lot of territory without being exhaustive.</p>
1297 </div>
1298
1299 <!-- ======================================================================= -->
1300 <div class="doc_subsection"><a name="llvmtest"><tt>test-suite</tt></a></div>
1301 <div class="doc_text">
1302   <p>This is not a directory in the normal llvm module; it is a separate
1303   Subversion
1304   module that must be checked out (usually to <tt>projects/test-suite</tt>).
1305   This
1306   module contains a comprehensive correctness, performance, and benchmarking
1307   test
1308   suite for LLVM. It is a separate Subversion module because not every LLVM
1309   user is
1310   interested in downloading or building such a comprehensive test suite. For
1311   further details on this test suite, please see the
1312   <a href="TestingGuide.html">Testing Guide</a> document.</p>
1313 </div>
1314
1315 <!-- ======================================================================= -->
1316 <div class="doc_subsection"><a name="tools"><tt>llvm/tools</tt></a></div>
1317 <div class="doc_text">
1318
1319 <p>The <b>tools</b> directory contains the executables built out of the
1320 libraries above, which form the main part of the user interface.  You can
1321 always get help for a tool by typing <tt>tool_name --help</tt>.  The
1322 following is a brief introduction to the most important tools.  More detailed
1323 information is in the <a href="CommandGuide/index.html">Command Guide</a>.</p>
1324
1325 <dl>
1326
1327   <dt><tt><b>bugpoint</b></tt></dt>
1328   <dd><tt>bugpoint</tt> is used to debug
1329   optimization passes or code generation backends by narrowing down the
1330   given test case to the minimum number of passes and/or instructions that
1331   still cause a problem, whether it is a crash or miscompilation. See <a
1332   href="HowToSubmitABug.html">HowToSubmitABug.html</a> for more information
1333   on using <tt>bugpoint</tt>.</dd>
1334
1335   <dt><tt><b>llvmc</b></tt></dt>
1336   <dd>The LLVM Compiler Driver. This program can
1337   be configured to utilize both LLVM and non-LLVM compilation tools to enable
1338   pre-processing, translation, optimization, assembly, and linking of programs
1339   all from one command line. <tt>llvmc</tt> also takes care of processing the
1340   dependent libraries found in bitcode. This reduces the need to get the
1341   traditional <tt>-l&lt;name&gt;</tt> options right on the command line. Please
1342   note that this tool, while functional, is still experimental and not feature
1343   complete.</dd>
1344
1345   <dt><tt><b>llvm-ar</b></tt></dt>
1346   <dd>The archiver produces an archive containing
1347   the given LLVM bitcode files, optionally with an index for faster
1348   lookup.</dd>
1349
1350   <dt><tt><b>llvm-as</b></tt></dt>
1351   <dd>The assembler transforms the human readable LLVM assembly to LLVM
1352   bitcode.</dd>
1353
1354   <dt><tt><b>llvm-dis</b></tt></dt>
1355   <dd>The disassembler transforms the LLVM bitcode to human readable
1356   LLVM assembly.</dd>
1357
1358   <dt><tt><b>llvm-ld</b></tt></dt>
1359   <dd><tt>llvm-ld</tt> is a general purpose and extensible linker for LLVM.
1360   This is the linker invoked by <tt>llvmc</tt>. It performsn standard link time
1361   optimizations and allows optimization modules to be loaded and run so that
1362   language specific optimizations can be applied at link time.</dd>
1363
1364   <dt><tt><b>llvm-link</b></tt></dt>
1365   <dd><tt>llvm-link</tt>, not surprisingly, links multiple LLVM modules into
1366   a single program.</dd>
1367
1368   <dt><tt><b>lli</b></tt></dt>
1369   <dd><tt>lli</tt> is the LLVM interpreter, which
1370   can directly execute LLVM bitcode (although very slowly...). For architectures
1371   that support it (currently x86, Sparc, and PowerPC), by default, <tt>lli</tt>
1372   will function as a Just-In-Time compiler (if the functionality was compiled
1373   in), and will execute the code <i>much</i> faster than the interpreter.</dd>
1374
1375   <dt><tt><b>llc</b></tt></dt>
1376   <dd> <tt>llc</tt> is the LLVM backend compiler, which
1377   translates LLVM bitcode to a native code assembly file or to C code (with
1378   the -march=c option).</dd>
1379
1380   <dt><tt><b>llvm-gcc</b></tt></dt>
1381   <dd><tt>llvm-gcc</tt> is a GCC-based C frontend that has been retargeted to
1382   use LLVM as its backend instead of GCC's RTL backend. It can also emit LLVM
1383   bitcode or assembly (with the <tt>-emit-llvm</tt> option) instead of the
1384   usual machine code output.  It works just like any other GCC compiler,
1385   taking the typical <tt>-c, -S, -E, -o</tt> options that are typically used.
1386   Additionally, the the source code for <tt>llvm-gcc</tt> is available as a
1387   separate Subversion module.</dd>
1388
1389   <dt><tt><b>opt</b></tt></dt>
1390   <dd><tt>opt</tt> reads LLVM bitcode, applies a series of LLVM to LLVM
1391   transformations (which are specified on the command line), and then outputs
1392   the resultant bitcode.  The '<tt>opt --help</tt>' command is a good way to
1393   get a list of the program transformations available in LLVM.<br>
1394   <dd><tt>opt</tt> can also be used to run a specific analysis on an input
1395   LLVM bitcode file and print out the results.  It is primarily useful for
1396   debugging analyses, or familiarizing yourself with what an analysis does.</dd>
1397 </dl>
1398 </div>
1399
1400 <!-- ======================================================================= -->
1401 <div class="doc_subsection"><a name="utils"><tt>llvm/utils</tt></a></div>
1402 <div class="doc_text">
1403
1404 <p>This directory contains utilities for working with LLVM source code, and some
1405 of the utilities are actually required as part of the build process because they
1406 are code generators for parts of LLVM infrastructure.</p>
1407
1408 <dl>
1409   <dt><tt><b>codegen-diff</b></tt> <dd><tt>codegen-diff</tt> is a script
1410   that finds differences between code that LLC generates and code that LLI
1411   generates. This is a useful tool if you are debugging one of them,
1412   assuming that the other generates correct output. For the full user
1413   manual, run <tt>`perldoc codegen-diff'</tt>.<br><br>
1414
1415   <dt><tt><b>emacs/</b></tt> <dd>The <tt>emacs</tt> directory contains
1416   syntax-highlighting files which will work with Emacs and XEmacs editors,
1417   providing syntax highlighting support for LLVM assembly files and TableGen
1418   description files. For information on how to use the syntax files, consult
1419   the <tt>README</tt> file in that directory.<br><br>
1420
1421   <dt><tt><b>getsrcs.sh</b></tt> <dd>The <tt>getsrcs.sh</tt> script finds
1422   and outputs all non-generated source files, which is useful if one wishes
1423   to do a lot of development across directories and does not want to
1424   individually find each file. One way to use it is to run, for example:
1425   <tt>xemacs `utils/getsources.sh`</tt> from the top of your LLVM source
1426   tree.<br><br>
1427
1428   <dt><tt><b>llvmgrep</b></tt></dt>
1429   <dd>This little tool performs an "egrep -H -n" on each source file in LLVM and
1430   passes to it a regular expression provided on <tt>llvmgrep</tt>'s command
1431   line. This is a very efficient way of searching the source base for a
1432   particular regular expression.</dd>
1433
1434   <dt><tt><b>makellvm</b></tt> <dd>The <tt>makellvm</tt> script compiles all
1435   files in the current directory and then compiles and links the tool that
1436   is the first argument. For example, assuming you are in the directory
1437   <tt>llvm/lib/Target/Sparc</tt>, if <tt>makellvm</tt> is in your path,
1438   simply running <tt>makellvm llc</tt> will make a build of the current
1439   directory, switch to directory <tt>llvm/tools/llc</tt> and build it,
1440   causing a re-linking of LLC.<br><br>
1441
1442   <dt><tt><b>NewNightlyTest.pl</b></tt> and
1443   <tt><b>NightlyTestTemplate.html</b></tt> <dd>These files are used in a
1444   cron script to generate nightly status reports of the functionality of
1445   tools, and the results can be seen by following the appropriate link on
1446   the <a href="http://llvm.org/">LLVM homepage</a>.<br><br>
1447
1448   <dt><tt><b>TableGen/</b></tt> <dd>The <tt>TableGen</tt> directory contains
1449   the tool used to generate register descriptions, instruction set
1450   descriptions, and even assemblers from common TableGen description
1451   files.<br><br>
1452
1453   <dt><tt><b>vim/</b></tt> <dd>The <tt>vim</tt> directory contains
1454   syntax-highlighting files which will work with the VIM editor, providing
1455   syntax highlighting support for LLVM assembly files and TableGen
1456   description files. For information on how to use the syntax files, consult
1457   the <tt>README</tt> file in that directory.<br><br>
1458
1459 </dl>
1460
1461 </div>
1462
1463 <!-- ======================================================================= -->
1464 <div class="doc_subsection"><a name="win32"><tt>llvm/win32</tt></a></div>
1465 <div class="doc_text">
1466   <p>This directory contains build scripts and project files for use with
1467   Visual C++. This allows developers on Windows to build LLVM without the need
1468   for Cygwin. The contents of this directory should be considered experimental
1469   at this time.
1470   </p>
1471 </div>
1472 <!-- *********************************************************************** -->
1473 <div class="doc_section">
1474   <a name="tutorial">An Example Using the LLVM Tool Chain</a>
1475 </div>
1476 <!-- *********************************************************************** -->
1477
1478 <div class="doc_text">
1479 <p>This section gives an example of using LLVM.  llvm-gcc3 is now obsolete,
1480 so we only include instructions for llvm-gcc4.
1481 </p>
1482
1483 <p><b>Note:</b> The <i>gcc4</i> frontend's invocation is <b><i>considerably different</i></b>
1484 from the previous <i>gcc3</i> frontend. In particular, the <i>gcc4</i> frontend <b><i>does not</i></b>
1485 create bitcode by default: <i>gcc4</i> produces native code. As the example below illustrates,
1486 the '--emit-llvm' flag is needed to produce LLVM bitcode output. For <i>makefiles</i> and
1487 <i>configure</i> scripts, the CFLAGS variable needs '--emit-llvm' to produce bitcode
1488 output.</p>
1489 </div>
1490
1491 <!-- ======================================================================= -->
1492 <div class="doc_subsection"><a name="tutorial4">Example with llvm-gcc4</a></div>
1493
1494 <div class="doc_text">
1495
1496 <ol>
1497   <li><p>First, create a simple C file, name it 'hello.c':</p>
1498
1499 <div class="doc_code">
1500 <pre>
1501 #include &lt;stdio.h&gt;
1502
1503 int main() {
1504   printf("hello world\n");
1505   return 0;
1506 }
1507 </pre></div></li>
1508
1509   <li><p>Next, compile the C file into a native executable:</p>
1510
1511       <div class="doc_code"><pre>% llvm-gcc hello.c -o hello</pre></div>
1512
1513       <p>Note that llvm-gcc works just like GCC by default.  The standard -S and
1514         -c arguments work as usual (producing a native .s or .o file,
1515         respectively).</p></li>
1516
1517   <li><p>Next, compile the C file into a LLVM bitcode file:</p>
1518
1519       <div class="doc_code">
1520       <pre>% llvm-gcc -O3 -emit-llvm hello.c -c -o hello.bc</pre></div>
1521
1522       <p>The -emit-llvm option can be used with the -S or -c options to emit an
1523          LLVM ".ll" or ".bc" file (respectively) for the code.  This allows you
1524          to use the <a href="CommandGuide/index.html">standard LLVM tools</a> on
1525          the bitcode file.</p>
1526
1527       <p>Unlike llvm-gcc3, llvm-gcc4 correctly responds to -O[0123] arguments.
1528          </p></li>
1529
1530   <li><p>Run the program in both forms. To run the program, use:</p>
1531
1532       <div class="doc_code"><pre>% ./hello</pre></div>
1533
1534       <p>and</p>
1535
1536       <div class="doc_code"><pre>% lli hello.bc</pre></div>
1537
1538       <p>The second examples shows how to invoke the LLVM JIT, <a
1539        href="CommandGuide/html/lli.html">lli</a>.</p></li>
1540
1541   <li><p>Use the <tt>llvm-dis</tt> utility to take a look at the LLVM assembly
1542       code:</p>
1543
1544 <div class="doc_code">
1545 <pre>llvm-dis &lt; hello.bc | less</pre>
1546 </div></li>
1547
1548   <li><p>Compile the program to native assembly using the LLC code
1549       generator:</p>
1550
1551       <div class="doc_code"><pre>% llc hello.bc -o hello.s</pre></div></li>
1552
1553   <li><p>Assemble the native assembly language file into a program:</p>
1554
1555 <div class="doc_code">
1556 <pre>
1557 <b>Solaris:</b> % /opt/SUNWspro/bin/cc -xarch=v9 hello.s -o hello.native
1558
1559 <b>Others:</b>  % gcc hello.s -o hello.native
1560 </pre>
1561 </div></li>
1562
1563   <li><p>Execute the native code program:</p>
1564
1565       <div class="doc_code"><pre>% ./hello.native</pre></div>
1566
1567       <p>Note that using llvm-gcc to compile directly to native code (i.e. when
1568          the -emit-llvm option is not present) does steps 6/7/8 for you.</p>
1569         </li>
1570
1571 </ol>
1572
1573 </div>
1574
1575
1576 <!-- *********************************************************************** -->
1577 <div class="doc_section">
1578   <a name="problems">Common Problems</a>
1579 </div>
1580 <!-- *********************************************************************** -->
1581
1582 <div class="doc_text">
1583
1584 <p>If you are having problems building or using LLVM, or if you have any other
1585 general questions about LLVM, please consult the <a href="FAQ.html">Frequently
1586 Asked Questions</a> page.</p>
1587
1588 </div>
1589
1590 <!-- *********************************************************************** -->
1591 <div class="doc_section">
1592   <a name="links">Links</a>
1593 </div>
1594 <!-- *********************************************************************** -->
1595
1596 <div class="doc_text">
1597
1598 <p>This document is just an <b>introduction</b> on how to use LLVM to do
1599 some simple things... there are many more interesting and complicated things
1600 that you can do that aren't documented here (but we'll gladly accept a patch
1601 if you want to write something up!).  For more information about LLVM, check
1602 out:</p>
1603
1604 <ul>
1605   <li><a href="http://llvm.org/">LLVM homepage</a></li>
1606   <li><a href="http://llvm.org/doxygen/">LLVM doxygen tree</a></li>
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1612
1613 <!-- *********************************************************************** -->
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1621
1622   <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
1623   <a href="http://llvm.x10sys.com/rspencer/">Reid Spencer</a><br>
1624   <a href="http://llvm.org">The LLVM Compiler Infrastructure</a><br>
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