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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
 549 <p><b>GNU ld 2.16.X</b>. Some 2.16.X versions of the ld linker will produce very
 550 long warning messages complaining that some ".gnu.linkonce.t.*" symbol was
 551 defined in a discarded section. You can safely ignore these messages as they are
 552 erroneous and the linkage is correct.  These messages disappear using ld
 553 2.17.</p>
 554
 555 <p><b>GNU binutils 2.17</b>: Binutils 2.17 contains <a
 556 href="http://sourceware.org/bugzilla/show_bug.cgi?id=3111">a bug</a> which
 557 causes huge link times (minutes instead of seconds) when building LLVM.  We
 558 recommend upgrading to a newer version (2.17.50.0.4 or later).</p>
 559
 560 <p><b>GNU Binutils 2.19.1 Gold</b>: This version of Gold contained
 561 <a href="http://sourceware.org/bugzilla/show_bug.cgi?id=9836">a bug</a>
 562 which causes intermittent failures when building LLVM with position independent
 563 code.  The symptom is an error about cyclic dependencies.  We recommend
 564 upgrading to a newer version of Gold.</p>
 565
 566 </div>
 567
 568
 569
 570 <!-- *********************************************************************** -->
 571 <div class="doc_section">
 572   <a name="starting"><b>Getting Started with LLVM</b></a>
 573 </div>
 574 <!-- *********************************************************************** -->
 575
 576 <div class="doc_text">
 577
 578 <p>The remainder of this guide is meant to get you up and running with
 579 LLVM and to give you some basic information about the LLVM environment.</p>
 580
 581 <p>The later sections of this guide describe the <a
 582 href="#layout">general layout</a> of the the LLVM source tree, a <a
 583 href="#tutorial">simple example</a> using the LLVM tool chain, and <a
 584 href="#links">links</a> to find more information about LLVM or to get
 585 help via e-mail.</p>
 586 </div>
 587
 588 <!-- ======================================================================= -->
 589 <div class="doc_subsection">
 590   <a name="terminology">Terminology and Notation</a>
 591 </div>
 592
 593 <div class="doc_text">
 594
 595 <p>Throughout this manual, the following names are used to denote paths
 596 specific to the local system and working environment.  <i>These are not
 597 environment variables you need to set but just strings used in the rest
 598 of this document below</i>.  In any of the examples below, simply replace
 599 each of these names with the appropriate pathname on your local system.
 600 All these paths are absolute:</p>
 601
 602 <dl>
 603     <dt>SRC_ROOT
 604     <dd>
 605     This is the top level directory of the LLVM source tree.
 606     <br><br>
 607
 608     <dt>OBJ_ROOT
 609     <dd>
 610     This is the top level directory of the LLVM object tree (i.e. the
 611     tree where object files and compiled programs will be placed.  It
 612     can be the same as SRC_ROOT).
 613     <br><br>
 614
 615     <dt>LLVMGCCDIR
 616     <dd>
 617     This is where the LLVM GCC Front End is installed.
 618     <p>
 619     For the pre-built GCC front end binaries, the LLVMGCCDIR is
 620     <tt>llvm-gcc/<i>platform</i>/llvm-gcc</tt>.
 621 </dl>
 622
 623 </div>
 624
 625 <!-- ======================================================================= -->
 626 <div class="doc_subsection">
 627   <a name="environment">Setting Up Your Environment</a>
 628 </div>
 629
 630 <div class="doc_text">
 631
 632 <p>
 633 In order to compile and use LLVM, you may need to set some environment
 634 variables.
 635
 636 <dl>
 637   <dt><tt>LLVM_LIB_SEARCH_PATH</tt>=<tt>/path/to/your/bitcode/libs</tt></dt>
 638   <dd>[Optional] This environment variable helps LLVM linking tools find the
 639   locations of your bitcode libraries. It is provided only as a
 640   convenience since you can specify the paths using the -L options of the
 641   tools and the C/C++ front-end will automatically use the bitcode files
 642   installed in its
 643   <tt>lib</tt> directory.</dd>
 644 </dl>
 645
 646 </div>
 647
 648 <!-- ======================================================================= -->
 649 <div class="doc_subsection">
 650   <a name="unpack">Unpacking the LLVM Archives</a>
 651 </div>
 652
 653 <div class="doc_text">
 654
 655 <p>
 656 If you have the LLVM distribution, you will need to unpack it before you
 657 can begin to compile it.  LLVM is distributed as a set of two files: the LLVM
 658 suite and the LLVM GCC front end compiled for your platform.  There is an
 659 additional test suite that is optional.  Each file is a TAR archive that is
 660 compressed with the gzip program.
 661 </p>
 662
 663 <p>The files are as follows, with <em>x.y</em> marking the version number:
 664 <dl>
 665   <dt><tt>llvm-x.y.tar.gz</tt></dt>
 666   <dd>Source release for the LLVM libraries and tools.<br></dd>
 667
 668   <dt><tt>llvm-test-x.y.tar.gz</tt></dt>
 669   <dd>Source release for the LLVM test suite.</dd>
 670
 671   <dt><tt>llvm-gcc-4.2-x.y.source.tar.gz</tt></dt>
 672   <dd>Source release of the llvm-gcc-4.2 front end.  See README.LLVM in the root
 673       directory for build instructions.<br></dd>
 674
 675   <dt><tt>llvm-gcc-4.2-x.y-platform.tar.gz</tt></dt>
 676   <dd>Binary release of the llvm-gcc-4.2 front end for a specific platform.<br></dd>
 677
 678 </dl>
 679
 680 </div>
 681
 682 <!-- ======================================================================= -->
 683 <div class="doc_subsection">
 684   <a name="checkout">Checkout LLVM from Subversion</a>
 685 </div>
 686
 687 <div class="doc_text">
 688
 689 <p>If you have access to our Subversion repository, you can get a fresh copy of
 690 the entire source code.  All you need to do is check it out from Subversion as
 691 follows:</p>
 692
 693 <ul>
 694   <li><tt>cd <i>where-you-want-llvm-to-live</i></tt></li>
 695   <li>Read-Only: <tt>svn co http://llvm.org/svn/llvm-project/llvm/trunk llvm</tt></li>
 696   <li>Read-Write:<tt>svn co https://user@llvm.org/svn/llvm-project/llvm/trunk
 697     llvm</tt></li>
 698 </ul>
 699
 700
 701 <p>This will create an '<tt>llvm</tt>' directory in the current
 702 directory and fully populate it with the LLVM source code, Makefiles,
 703 test directories, and local copies of documentation files.</p>
 704
 705 <p>If you want to get a specific release (as opposed to the most recent
 706 revision), you can checkout it from the '<tt>tags</tt>' directory (instead of
 707 '<tt>trunk</tt>'). The following releases are located in the following
 708 subdirectories of the '<tt>tags</tt>' directory:</p>
 709
 710 <ul>
 711 <li>Release 2.5: <b>RELEASE_25</b></li>
 712 <li>Release 2.4: <b>RELEASE_24</b></li>
 713 <li>Release 2.3: <b>RELEASE_23</b></li>
 714 <li>Release 2.2: <b>RELEASE_22</b></li>
 715 <li>Release 2.1: <b>RELEASE_21</b></li>
 716 <li>Release 2.0: <b>RELEASE_20</b></li>
 717 <li>Release 1.9: <b>RELEASE_19</b></li>
 718 <li>Release 1.8: <b>RELEASE_18</b></li>
 719 <li>Release 1.7: <b>RELEASE_17</b></li>
 720 <li>Release 1.6: <b>RELEASE_16</b></li>
 721 <li>Release 1.5: <b>RELEASE_15</b></li>
 722 <li>Release 1.4: <b>RELEASE_14</b></li>
 723 <li>Release 1.3: <b>RELEASE_13</b></li>
 724 <li>Release 1.2: <b>RELEASE_12</b></li>
 725 <li>Release 1.1: <b>RELEASE_11</b></li>
 726 <li>Release 1.0: <b>RELEASE_1</b></li>
 727 </ul>
 728
 729 <p>If you would like to get the LLVM test suite (a separate package as of 1.4),
 730 you get it from the Subversion repository:</p>
 731
 732 <div class="doc_code">
 733 <pre>
 734 % cd llvm/projects
 735 % svn co http://llvm.org/svn/llvm-project/test-suite/trunk llvm-test
 736 </pre>
 737 </div>
 738
 739 <p>By placing it in the <tt>llvm/projects</tt>, it will be automatically
 740 configured by the LLVM configure script as well as automatically updated when
 741 you run <tt>svn update</tt>.</p>
 742
 743 <p>If you would like to get the GCC front end source code, you can also get it
 744 and build it yourself.  Please follow <a href="GCCFEBuildInstrs.html">these
 745 instructions</a> to successfully get and build the LLVM GCC front-end.</p>
 746
 747 </div>
 748
 749 <!-- ======================================================================= -->
 750 <div class="doc_subsection">
 751   <a name="installcf">Install the GCC Front End</a>
 752 </div>
 753
 754 <div class="doc_text">
 755
 756 <p>Before configuring and compiling the LLVM suite, you can optionally extract the
 757 LLVM GCC front end from the binary distribution.  It is used for running the
 758 llvm-test testsuite and for compiling C/C++ programs.  Note that you can optionally
 759 <a href="GCCFEBuildInstrs.html">build llvm-gcc yourself</a> after building the
 760 main LLVM repository.</p>
 761
 762 <p>To install the GCC front end, do the following:</p>
 763
 764 <ol>
 765   <li><tt>cd <i>where-you-want-the-front-end-to-live</i></tt></li>
 766   <li><tt>gunzip --stdout llvm-gcc-4.2-<i>version</i>-<i>platform</i>.tar.gz | tar -xvf
 767       -</tt></li>
 768 </ol>
 769
 770 <p>Once the binary is uncompressed, you should add a symlink for llvm-gcc and
 771 llvm-g++ to some directory in your path.  When you configure LLVM, it will
 772 automatically detect llvm-gcc's presence (if it is in your path) enabling its
 773 use in llvm-test.  Note that you can always build or install llvm-gcc at any
 774 pointer after building the main LLVM repository: just reconfigure llvm and
 775 llvm-test will pick it up.
 776 </p>
 777
 778 <p>The binary versions of the GCC front end may not suit all of your needs.  For
 779 example, the binary distribution may include an old version of a system header
 780 file, not "fix" a header file that needs to be fixed for GCC, or it may be
 781 linked with libraries not available on your system.</p>
 782
 783 <p>In cases like these, you may want to try <a
 784 href="GCCFEBuildInstrs.html">building the GCC front end from source.</a> This is
 785 much easier now than it was in the past.</p>
 786
 787 </div>
 788
 789 <!-- ======================================================================= -->
 790 <div class="doc_subsection">
 791   <a name="config">Local LLVM Configuration</a>
 792 </div>
 793
 794 <div class="doc_text">
 795
 796   <p>Once checked out from the Subversion repository, the LLVM suite source
 797   code must be
 798 configured via the <tt>configure</tt> script.  This script sets variables in the
 799 various <tt>*.in</tt> files, most notably <tt>llvm/Makefile.config</tt> and
 800 <tt>llvm/include/Config/config.h</tt>.  It also populates <i>OBJ_ROOT</i> with
 801 the Makefiles needed to begin building LLVM.</p>
 802
 803 <p>The following environment variables are used by the <tt>configure</tt>
 804 script to configure the build system:</p>
 805
 806 <table summary="LLVM configure script environment variables">
 807   <tr><th>Variable</th><th>Purpose</th></tr>
 808   <tr>
 809     <td>CC</td>
 810     <td>Tells <tt>configure</tt> which C compiler to use.  By default,
 811         <tt>configure</tt> will look for the first GCC C compiler in
 812         <tt>PATH</tt>.  Use this variable to override
 813         <tt>configure</tt>'s default behavior.</td>
 814   </tr>
 815   <tr>
 816     <td>CXX</td>
 817     <td>Tells <tt>configure</tt> which C++ compiler to use.  By default,
 818        <tt>configure</tt> will look for the first GCC C++ compiler in
 819        <tt>PATH</tt>.  Use this variable to override
 820        <tt>configure</tt>'s default behavior.</td>
 821   </tr>
 822 </table>
 823
 824 <p>The following options can be used to set or enable LLVM specific options:</p>
 825
 826 <dl>
 827   <dt><i>--with-llvmgccdir</i></dt>
 828   <dd>Path to the LLVM C/C++ FrontEnd to be used with this LLVM configuration.
 829   The value of this option should specify the full pathname of the C/C++ Front
 830   End to be used. If this option is not provided, the PATH will be searched for
 831   a program named <i>llvm-gcc</i> and the C/C++ FrontEnd install directory will
 832   be inferred from the path found. If the option is not given, and no llvm-gcc
 833   can be found in the path then a warning will be produced by
 834   <tt>configure</tt> indicating this situation. LLVM may still be built with
 835   the <tt>tools-only</tt> target but attempting to build the runtime libraries
 836   will fail as these libraries require llvm-gcc and llvm-g++. See
 837   <a href="#installcf">Install the GCC Front End</a> for details on installing
 838   the C/C++ Front End. See
 839   <a href="GCCFEBuildInstrs.html">Bootstrapping the LLVM C/C++ Front-End</a>
 840   for details on building the C/C++ Front End.</dd>
 841   <dt><i>--with-tclinclude</i></dt>
 842   <dd>Path to the tcl include directory under which <tt>tclsh</tt> can be
 843   found. Use this if you have multiple tcl installations on your machine and you
 844   want to use a specific one (8.x) for LLVM. LLVM only uses tcl for running the
 845   dejagnu based test suite in <tt>llvm/test</tt>. If you don't specify this
 846   option, the LLVM configure script will search for the tcl 8.4 and 8.3
 847   releases.
 848   <br><br>
 849   </dd>
 850   <dt><i>--enable-optimized</i></dt>
 851   <dd>
 852     Enables optimized compilation (debugging symbols are removed
 853     and GCC optimization flags are enabled). Note that this is the default
 854     setting     if you are using the LLVM distribution. The default behavior
 855     of an Subversion checkout is to use an unoptimized build (also known as a
 856     debug build).
 857     <br><br>
 858   </dd>
 859   <dt><i>--enable-debug-runtime</i></dt>
 860   <dd>
 861     Enables debug symbols in the runtime libraries. The default is to strip
 862     debug symbols from the runtime libraries.
 863   </dd>
 864   <dt><i>--enable-jit</i></dt>
 865   <dd>
 866     Compile the Just In Time (JIT) compiler functionality.  This is not
 867     available
 868     on all platforms.  The default is dependent on platform, so it is best
 869     to explicitly enable it if you want it.
 870     <br><br>
 871   </dd>
 872   <dt><i>--enable-targets=</i><tt>target-option</tt></dt>
 873   <dd>Controls which targets will be built and linked into llc. The default
 874   value for <tt>target_options</tt> is "all" which builds and links all
 875   available targets.  The value "host-only" can be specified to build only a
 876   native compiler (no cross-compiler targets available). The "native" target is
 877   selected as the target of the build host. You can also specify a comma
 878   separated list of target names that you want available in llc. The target
 879   names use all lower case. The current set of targets is: <br>
 880   <tt>alpha, ia64, powerpc, skeleton, sparc, x86</tt>.
 881   <br><br></dd>
 882   <dt><i>--enable-doxygen</i></dt>
 883   <dd>Look for the doxygen program and enable construction of doxygen based
 884   documentation from the source code. This is disabled by default because
 885   generating the documentation can take a long time and producess 100s of
 886   megabytes of output.</dd>
 887   <dt><i>--with-udis86</i></dt>
 888   <dd>LLVM can use external disassembler library for various purposes (now it's
 889   used only for examining code produced by JIT). This option will enable usage
 890   of <a href="http://udis86.sourceforge.net/">udis86</a> x86 (both 32 and 64
 891   bits) disassembler library.</dd>
 892 </dl>
 893
 894 <p>To configure LLVM, follow these steps:</p>
 895
 896 <ol>
 897     <li><p>Change directory into the object root directory:</p>
 898
 899     <div class="doc_code"><pre>% cd <i>OBJ_ROOT</i></pre></div></li>
 900
 901     <li><p>Run the <tt>configure</tt> script located in the LLVM source
 902     tree:</p>
 903
 904     <div class="doc_code">
 905     <pre>% <i>SRC_ROOT</i>/configure --prefix=/install/path [other options]</pre>
 906     </div></li>
 907 </ol>
 908
 909 </div>
 910
 911 <!-- ======================================================================= -->
 912 <div class="doc_subsection">
 913   <a name="compile">Compiling the LLVM Suite Source Code</a>
 914 </div>
 915
 916 <div class="doc_text">
 917
 918 <p>Once you have configured LLVM, you can build it.  There are three types of
 919 builds:</p>
 920
 921 <dl>
 922     <dt>Debug Builds
 923     <dd>
 924     These builds are the default when one is using an Subversion checkout and
 925     types <tt>gmake</tt> (unless the <tt>--enable-optimized</tt> option was
 926     used during configuration).  The build system will compile the tools and
 927     libraries with debugging information.  To get a Debug Build using the
 928     LLVM distribution the <tt>--disable-optimized</tt> option must be passed
 929     to <tt>configure</tt>.
 930     <br><br>
 931
 932     <dt>Release (Optimized) Builds
 933     <dd>
 934     These builds are enabled with the <tt>--enable-optimized</tt> option to
 935     <tt>configure</tt> or by specifying <tt>ENABLE_OPTIMIZED=1</tt> on the
 936     <tt>gmake</tt> command line.  For these builds, the build system will
 937     compile the tools and libraries with GCC optimizations enabled and strip
 938     debugging information from the libraries and executables it generates.
 939     Note that Release Builds are default when using an LLVM distribution.
 940     <br><br>
 941
 942     <dt>Profile Builds
 943     <dd>
 944     These builds are for use with profiling.  They compile profiling
 945     information into the code for use with programs like <tt>gprof</tt>.
 946     Profile builds must be started by specifying <tt>ENABLE_PROFILING=1</tt>
 947     on the <tt>gmake</tt> command line.
 948 </dl>
 949
 950 <p>Once you have LLVM configured, you can build it by entering the
 951 <i>OBJ_ROOT</i> directory and issuing the following command:</p>
 952
 953 <div class="doc_code"><pre>% gmake</pre></div>
 954
 955 <p>If the build fails, please <a href="#brokengcc">check here</a> to see if you
 956 are using a version of GCC that is known not to compile LLVM.</p>
 957
 958 <p>
 959 If you have multiple processors in your machine, you may wish to use some of
 960 the parallel build options provided by GNU Make.  For example, you could use the
 961 command:</p>
 962
 963 <div class="doc_code"><pre>% gmake -j2</pre></div>
 964
 965 <p>There are several special targets which are useful when working with the LLVM
 966 source code:</p>
 967
 968 <dl>
 969   <dt><tt>gmake clean</tt>
 970   <dd>
 971   Removes all files generated by the build.  This includes object files,
 972   generated C/C++ files, libraries, and executables.
 973   <br><br>
 974
 975   <dt><tt>gmake dist-clean</tt>
 976   <dd>
 977   Removes everything that <tt>gmake clean</tt> does, but also removes files
 978   generated by <tt>configure</tt>.  It attempts to return the source tree to the
 979   original state in which it was shipped.
 980   <br><br>
 981
 982   <dt><tt>gmake install</tt>
 983   <dd>
 984   Installs LLVM header files, libraries, tools, and documentation in a
 985   hierarchy
 986   under $PREFIX, specified with <tt>./configure --prefix=[dir]</tt>, which
 987   defaults to <tt>/usr/local</tt>.
 988   <br><br>
 989
 990   <dt><tt>gmake -C runtime install-bytecode</tt>
 991   <dd>
 992   Assuming you built LLVM into $OBJDIR, when this command is run, it will
 993   install bitcode libraries into the GCC front end's bitcode library
 994   directory.  If you need to update your bitcode libraries,
 995   this is the target to use once you've built them.
 996   <br><br>
 997 </dl>
 998
 999 <p>Please see the <a href="MakefileGuide.html">Makefile Guide</a> for further
1000 details on these <tt>make</tt> targets and descriptions of other targets
1001 available.</p>
1002
1003 <p>It is also possible to override default values from <tt>configure</tt> by
1004 declaring variables on the command line.  The following are some examples:</p>
1005
1006 <dl>
1007   <dt><tt>gmake ENABLE_OPTIMIZED=1</tt>
1008   <dd>
1009   Perform a Release (Optimized) build.
1010   <br><br>
1011
1012   <dt><tt>gmake ENABLE_OPTIMIZED=1 DISABLE_ASSERTIONS=1</tt>
1013   <dd>
1014   Perform a Release (Optimized) build without assertions enabled.
1015   <br><br>
1016
1017   <dt><tt>gmake ENABLE_OPTIMIZED=0</tt>
1018   <dd>
1019   Perform a Debug build.
1020   <br><br>
1021
1022   <dt><tt>gmake ENABLE_PROFILING=1</tt>
1023   <dd>
1024   Perform a Profiling build.
1025   <br><br>
1026
1027   <dt><tt>gmake VERBOSE=1</tt>
1028   <dd>
1029   Print what <tt>gmake</tt> is doing on standard output.
1030   <br><br>
1031
1032   <dt><tt>gmake TOOL_VERBOSE=1</tt></dt>
1033   <dd>Ask each tool invoked by the makefiles to print out what it is doing on
1034   the standard output. This also implies <tt>VERBOSE=1</tt>.
1035   <br><br></dd>
1036 </dl>
1037
1038 <p>Every directory in the LLVM object tree includes a <tt>Makefile</tt> to build
1039 it and any subdirectories that it contains.  Entering any directory inside the
1040 LLVM object tree and typing <tt>gmake</tt> should rebuild anything in or below
1041 that directory that is out of date.</p>
1042
1043 </div>
1044
1045 <!-- ======================================================================= -->
1046 <div class="doc_subsection">
1047   <a name="cross-compile">Cross-Compiling LLVM</a>
1048 </div>
1049
1050 <div class="doc_text">
1051   <p>It is possible to cross-compile LLVM itself. That is, you can create LLVM
1052   executables and libraries to be hosted on a platform different from the
1053   platform where they are build (a Canadian Cross build). To configure a
1054   cross-compile, supply the configure script with <tt>--build</tt> and
1055   <tt>--host</tt> options that are different. The values of these options must
1056   be legal target triples that your GCC compiler supports.</p>
1057
1058   <p>The result of such a build is executables that are not runnable on
1059   on the build host (--build option) but can be executed on the compile host
1060   (--host option).</p>
1061 </div>
1062
1063 <!-- ======================================================================= -->
1064 <div class="doc_subsection">
1065   <a name="objfiles">The Location of LLVM Object Files</a>
1066 </div>
1067
1068 <div class="doc_text">
1069
1070 <p>The LLVM build system is capable of sharing a single LLVM source tree among
1071 several LLVM builds.  Hence, it is possible to build LLVM for several different
1072 platforms or configurations using the same source tree.</p>
1073
1074 <p>This is accomplished in the typical autoconf manner:</p>
1075
1076 <ul>
1077   <li><p>Change directory to where the LLVM object files should live:</p>
1078
1079       <div class="doc_code"><pre>% cd <i>OBJ_ROOT</i></pre></div></li>
1080
1081   <li><p>Run the <tt>configure</tt> script found in the LLVM source
1082       directory:</p>
1083
1084       <div class="doc_code"><pre>% <i>SRC_ROOT</i>/configure</pre></div></li>
1085 </ul>
1086
1087 <p>The LLVM build will place files underneath <i>OBJ_ROOT</i> in directories
1088 named after the build type:</p>
1089
1090 <dl>
1091   <dt>Debug Builds
1092   <dd>
1093   <dl>
1094     <dt>Tools
1095     <dd><tt><i>OBJ_ROOT</i>/Debug/bin</tt>
1096     <dt>Libraries
1097     <dd><tt><i>OBJ_ROOT</i>/Debug/lib</tt>
1098   </dl>
1099   <br><br>
1100
1101   <dt>Release Builds
1102   <dd>
1103   <dl>
1104     <dt>Tools
1105     <dd><tt><i>OBJ_ROOT</i>/Release/bin</tt>
1106     <dt>Libraries
1107     <dd><tt><i>OBJ_ROOT</i>/Release/lib</tt>
1108   </dl>
1109   <br><br>
1110
1111   <dt>Profile Builds
1112   <dd>
1113   <dl>
1114     <dt>Tools
1115     <dd><tt><i>OBJ_ROOT</i>/Profile/bin</tt>
1116     <dt>Libraries
1117     <dd><tt><i>OBJ_ROOT</i>/Profile/lib</tt>
1118   </dl>
1119 </dl>
1120
1121 </div>
1122
1123 <!-- ======================================================================= -->
1124 <div class="doc_subsection">
1125   <a name="optionalconfig">Optional Configuration Items</a>
1126 </div>
1127
1128 <div class="doc_text">
1129
1130 <p>
1131 If you're running on a Linux system that supports the "<a
1132 href="http://www.tat.physik.uni-tuebingen.de/~rguenth/linux/binfmt_misc.html">binfmt_misc</a>"
1133 module, and you have root access on the system, you can set your system up to
1134 execute LLVM bitcode files directly. To do this, use commands like this (the
1135 first command may not be required if you are already using the module):</p>
1136
1137 <div class="doc_code">
1138 <pre>
1139 $ mount -t binfmt_misc none /proc/sys/fs/binfmt_misc
1140 $ echo ':llvm:M::llvm::/path/to/lli:' &gt; /proc/sys/fs/binfmt_misc/register
1141 $ chmod u+x hello.bc   (if needed)
1142 $ ./hello.bc
1143 </pre>
1144 </div>
1145
1146 <p>
1147 This allows you to execute LLVM bitcode files directly.  Thanks to Jack
1148 Cummings for pointing this out!
1149 </p>
1150
1151 </div>
1152
1153
1154 <!-- *********************************************************************** -->
1155 <div class="doc_section">
1156   <a name="layout"><b>Program Layout</b></a>
1157 </div>
1158 <!-- *********************************************************************** -->
1159
1160 <div class="doc_text">
1161
1162 <p>One useful source of information about the LLVM source base is the LLVM <a
1163 href="http://www.doxygen.org">doxygen</a> documentation available at <tt><a
1164 href="http://llvm.org/doxygen/">http://llvm.org/doxygen/</a></tt>.
1165 The following is a brief introduction to code layout:</p>
1166
1167 </div>
1168
1169 <!-- ======================================================================= -->
1170 <div class="doc_subsection"><a name="examples"><tt>llvm/examples</tt></a></div>
1171 <div class="doc_text">
1172   <p>This directory contains some simple examples of how to use the LLVM IR and
1173   JIT.</p>
1174 </div>
1175
1176 <!-- ======================================================================= -->
1177 <div class="doc_subsection"><a name="include"><tt>llvm/include</tt></a></div>
1178 <div class="doc_text">
1179
1180 <p>This directory contains public header files exported from the LLVM
1181 library. The three main subdirectories of this directory are:</p>
1182
1183 <dl>
1184   <dt><tt><b>llvm/include/llvm</b></tt></dt>
1185   <dd>This directory contains all of the LLVM specific header files.  This
1186   directory also has subdirectories for different portions of LLVM:
1187   <tt>Analysis</tt>, <tt>CodeGen</tt>, <tt>Target</tt>, <tt>Transforms</tt>,
1188   etc...</dd>
1189
1190   <dt><tt><b>llvm/include/llvm/Support</b></tt></dt>
1191   <dd>This directory contains generic support libraries that are provided with
1192   LLVM but not necessarily specific to LLVM. For example, some C++ STL utilities
1193   and a Command Line option processing library store their header files here.
1194   </dd>
1195
1196   <dt><tt><b>llvm/include/llvm/Config</b></tt></dt>
1197   <dd>This directory contains header files configured by the <tt>configure</tt>
1198   script.  They wrap "standard" UNIX and C header files.  Source code can
1199   include these header files which automatically take care of the conditional
1200   #includes that the <tt>configure</tt> script generates.</dd>
1201 </dl>
1202 </div>
1203
1204 <!-- ======================================================================= -->
1205 <div class="doc_subsection"><a name="lib"><tt>llvm/lib</tt></a></div>
1206 <div class="doc_text">
1207
1208 <p>This directory contains most of the source files of the LLVM system. In LLVM,
1209 almost all code exists in libraries, making it very easy to share code among the
1210 different <a href="#tools">tools</a>.</p>
1211
1212 <dl>
1213   <dt><tt><b>llvm/lib/VMCore/</b></tt></dt>
1214   <dd> This directory holds the core LLVM source files that implement core
1215   classes like Instruction and BasicBlock.</dd>
1216
1217   <dt><tt><b>llvm/lib/AsmParser/</b></tt></dt>
1218   <dd>This directory holds the source code for the LLVM assembly language parser
1219   library.</dd>
1220
1221   <dt><tt><b>llvm/lib/BitCode/</b></tt></dt>
1222   <dd>This directory holds code for reading and write LLVM bitcode.</dd>
1223
1224   <dt><tt><b>llvm/lib/Analysis/</b></tt><dd>This directory contains a variety of
1225   different program analyses, such as Dominator Information, Call Graphs,
1226   Induction Variables, Interval Identification, Natural Loop Identification,
1227   etc.</dd>
1228
1229   <dt><tt><b>llvm/lib/Transforms/</b></tt></dt>
1230   <dd> This directory contains the source code for the LLVM to LLVM program
1231   transformations, such as Aggressive Dead Code Elimination, Sparse Conditional
1232   Constant Propagation, Inlining, Loop Invariant Code Motion, Dead Global
1233   Elimination, and many others.</dd>
1234
1235   <dt><tt><b>llvm/lib/Target/</b></tt></dt>
1236   <dd> This directory contains files that describe various target architectures
1237   for code generation.  For example, the <tt>llvm/lib/Target/X86</tt>
1238   directory holds the X86 machine description while
1239   <tt>llvm/lib/Target/CBackend</tt> implements the LLVM-to-C converter.</dd>
1240
1241   <dt><tt><b>llvm/lib/CodeGen/</b></tt></dt>
1242   <dd> This directory contains the major parts of the code generator: Instruction
1243   Selector, Instruction Scheduling, and Register Allocation.</dd>
1244
1245   <dt><tt><b>llvm/lib/Debugger/</b></tt></dt>
1246   <dd> This directory contains the source level debugger library that makes
1247   it possible to instrument LLVM programs so that a debugger could identify
1248   source code locations at which the program is executing.</dd>
1249
1250   <dt><tt><b>llvm/lib/ExecutionEngine/</b></tt></dt>
1251   <dd> This directory contains libraries for executing LLVM bitcode directly
1252   at runtime in both interpreted and JIT compiled fashions.</dd>
1253
1254   <dt><tt><b>llvm/lib/Support/</b></tt></dt>
1255   <dd> This directory contains the source code that corresponds to the header
1256   files located in <tt>llvm/include/Support/</tt>.</dd>
1257
1258   <dt><tt><b>llvm/lib/System/</b></tt></dt>
1259   <dd>This directory contains the operating system abstraction layer that
1260   shields LLVM from platform-specific coding.</dd>
1261 </dl>
1262
1263 </div>
1264
1265 <!-- ======================================================================= -->
1266 <div class="doc_subsection"><a name="projects"><tt>llvm/projects</tt></a></div>
1267 <div class="doc_text">
1268   <p>This directory contains projects that are not strictly part of LLVM but are
1269   shipped with LLVM. This is also the directory where you should create your own
1270   LLVM-based projects. See <tt>llvm/projects/sample</tt> for an example of how
1271   to set up your own project.</p>
1272 </div>
1273
1274 <!-- ======================================================================= -->
1275 <div class="doc_subsection"><a name="runtime"><tt>llvm/runtime</tt></a></div>
1276 <div class="doc_text">
1277
1278 <p>This directory contains libraries which are compiled into LLVM bitcode and
1279 used when linking programs with the GCC front end.  Most of these libraries are
1280 skeleton versions of real libraries; for example, libc is a stripped down
1281 version of glibc.</p>
1282
1283 <p>Unlike the rest of the LLVM suite, this directory needs the LLVM GCC front
1284 end to compile.</p>
1285
1286 </div>
1287
1288 <!-- ======================================================================= -->
1289 <div class="doc_subsection"><a name="test"><tt>llvm/test</tt></a></div>
1290 <div class="doc_text">
1291   <p>This directory contains feature and regression tests and other basic sanity
1292   checks on the LLVM infrastructure. These are intended to run quickly and cover
1293   a lot of territory without being exhaustive.</p>
1294 </div>
1295
1296 <!-- ======================================================================= -->
1297 <div class="doc_subsection"><a name="llvmtest"><tt>test-suite</tt></a></div>
1298 <div class="doc_text">
1299   <p>This is not a directory in the normal llvm module; it is a separate
1300   Subversion
1301   module that must be checked out (usually to <tt>projects/test-suite</tt>).
1302   This
1303   module contains a comprehensive correctness, performance, and benchmarking
1304   test
1305   suite for LLVM. It is a separate Subversion module because not every LLVM
1306   user is
1307   interested in downloading or building such a comprehensive test suite. For
1308   further details on this test suite, please see the
1309   <a href="TestingGuide.html">Testing Guide</a> document.</p>
1310 </div>
1311
1312 <!-- ======================================================================= -->
1313 <div class="doc_subsection"><a name="tools"><tt>llvm/tools</tt></a></div>
1314 <div class="doc_text">
1315
1316 <p>The <b>tools</b> directory contains the executables built out of the
1317 libraries above, which form the main part of the user interface.  You can
1318 always get help for a tool by typing <tt>tool_name --help</tt>.  The
1319 following is a brief introduction to the most important tools.  More detailed
1320 information is in the <a href="CommandGuide/index.html">Command Guide</a>.</p>
1321
1322 <dl>
1323
1324   <dt><tt><b>bugpoint</b></tt></dt>
1325   <dd><tt>bugpoint</tt> is used to debug
1326   optimization passes or code generation backends by narrowing down the
1327   given test case to the minimum number of passes and/or instructions that
1328   still cause a problem, whether it is a crash or miscompilation. See <a
1329   href="HowToSubmitABug.html">HowToSubmitABug.html</a> for more information
1330   on using <tt>bugpoint</tt>.</dd>
1331
1332   <dt><tt><b>llvmc</b></tt></dt>
1333   <dd>The LLVM Compiler Driver. This program can
1334   be configured to utilize both LLVM and non-LLVM compilation tools to enable
1335   pre-processing, translation, optimization, assembly, and linking of programs
1336   all from one command line. <tt>llvmc</tt> also takes care of processing the
1337   dependent libraries found in bitcode. This reduces the need to get the
1338   traditional <tt>-l&lt;name&gt;</tt> options right on the command line. Please
1339   note that this tool, while functional, is still experimental and not feature
1340   complete.</dd>
1341
1342   <dt><tt><b>llvm-ar</b></tt></dt>
1343   <dd>The archiver produces an archive containing
1344   the given LLVM bitcode files, optionally with an index for faster
1345   lookup.</dd>
1346
1347   <dt><tt><b>llvm-as</b></tt></dt>
1348   <dd>The assembler transforms the human readable LLVM assembly to LLVM
1349   bitcode.</dd>
1350
1351   <dt><tt><b>llvm-dis</b></tt></dt>
1352   <dd>The disassembler transforms the LLVM bitcode to human readable
1353   LLVM assembly.</dd>
1354
1355   <dt><tt><b>llvm-ld</b></tt></dt>
1356   <dd><tt>llvm-ld</tt> is a general purpose and extensible linker for LLVM.
1357   This is the linker invoked by <tt>llvmc</tt>. It performsn standard link time
1358   optimizations and allows optimization modules to be loaded and run so that
1359   language specific optimizations can be applied at link time.</dd>
1360
1361   <dt><tt><b>llvm-link</b></tt></dt>
1362   <dd><tt>llvm-link</tt>, not surprisingly, links multiple LLVM modules into
1363   a single program.</dd>
1364
1365   <dt><tt><b>lli</b></tt></dt>
1366   <dd><tt>lli</tt> is the LLVM interpreter, which
1367   can directly execute LLVM bitcode (although very slowly...). For architectures
1368   that support it (currently x86, Sparc, and PowerPC), by default, <tt>lli</tt>
1369   will function as a Just-In-Time compiler (if the functionality was compiled
1370   in), and will execute the code <i>much</i> faster than the interpreter.</dd>
1371
1372   <dt><tt><b>llc</b></tt></dt>
1373   <dd> <tt>llc</tt> is the LLVM backend compiler, which
1374   translates LLVM bitcode to a native code assembly file or to C code (with
1375   the -march=c option).</dd>
1376
1377   <dt><tt><b>llvm-gcc</b></tt></dt>
1378   <dd><tt>llvm-gcc</tt> is a GCC-based C frontend that has been retargeted to
1379   use LLVM as its backend instead of GCC's RTL backend. It can also emit LLVM
1380   bitcode or assembly (with the <tt>-emit-llvm</tt> option) instead of the
1381   usual machine code output.  It works just like any other GCC compiler,
1382   taking the typical <tt>-c, -S, -E, -o</tt> options that are typically used.
1383   Additionally, the the source code for <tt>llvm-gcc</tt> is available as a
1384   separate Subversion module.</dd>
1385
1386   <dt><tt><b>opt</b></tt></dt>
1387   <dd><tt>opt</tt> reads LLVM bitcode, applies a series of LLVM to LLVM
1388   transformations (which are specified on the command line), and then outputs
1389   the resultant bitcode.  The '<tt>opt --help</tt>' command is a good way to
1390   get a list of the program transformations available in LLVM.<br>
1391   <dd><tt>opt</tt> can also be used to run a specific analysis on an input
1392   LLVM bitcode file and print out the results.  It is primarily useful for
1393   debugging analyses, or familiarizing yourself with what an analysis does.</dd>
1394 </dl>
1395 </div>
1396
1397 <!-- ======================================================================= -->
1398 <div class="doc_subsection"><a name="utils"><tt>llvm/utils</tt></a></div>
1399 <div class="doc_text">
1400
1401 <p>This directory contains utilities for working with LLVM source code, and some
1402 of the utilities are actually required as part of the build process because they
1403 are code generators for parts of LLVM infrastructure.</p>
1404
1405 <dl>
1406   <dt><tt><b>codegen-diff</b></tt> <dd><tt>codegen-diff</tt> is a script
1407   that finds differences between code that LLC generates and code that LLI
1408   generates. This is a useful tool if you are debugging one of them,
1409   assuming that the other generates correct output. For the full user
1410   manual, run <tt>`perldoc codegen-diff'</tt>.<br><br>
1411
1412   <dt><tt><b>emacs/</b></tt> <dd>The <tt>emacs</tt> directory contains
1413   syntax-highlighting files which will work with Emacs and XEmacs editors,
1414   providing syntax highlighting support for LLVM assembly files and TableGen
1415   description files. For information on how to use the syntax files, consult
1416   the <tt>README</tt> file in that directory.<br><br>
1417
1418   <dt><tt><b>getsrcs.sh</b></tt> <dd>The <tt>getsrcs.sh</tt> script finds
1419   and outputs all non-generated source files, which is useful if one wishes
1420   to do a lot of development across directories and does not want to
1421   individually find each file. One way to use it is to run, for example:
1422   <tt>xemacs `utils/getsources.sh`</tt> from the top of your LLVM source
1423   tree.<br><br>
1424
1425   <dt><tt><b>llvmgrep</b></tt></dt>
1426   <dd>This little tool performs an "egrep -H -n" on each source file in LLVM and
1427   passes to it a regular expression provided on <tt>llvmgrep</tt>'s command
1428   line. This is a very efficient way of searching the source base for a
1429   particular regular expression.</dd>
1430
1431   <dt><tt><b>makellvm</b></tt> <dd>The <tt>makellvm</tt> script compiles all
1432   files in the current directory and then compiles and links the tool that
1433   is the first argument. For example, assuming you are in the directory
1434   <tt>llvm/lib/Target/Sparc</tt>, if <tt>makellvm</tt> is in your path,
1435   simply running <tt>makellvm llc</tt> will make a build of the current
1436   directory, switch to directory <tt>llvm/tools/llc</tt> and build it,
1437   causing a re-linking of LLC.<br><br>
1438
1439   <dt><tt><b>NewNightlyTest.pl</b></tt> and
1440   <tt><b>NightlyTestTemplate.html</b></tt> <dd>These files are used in a
1441   cron script to generate nightly status reports of the functionality of
1442   tools, and the results can be seen by following the appropriate link on
1443   the <a href="http://llvm.org/">LLVM homepage</a>.<br><br>
1444
1445   <dt><tt><b>TableGen/</b></tt> <dd>The <tt>TableGen</tt> directory contains
1446   the tool used to generate register descriptions, instruction set
1447   descriptions, and even assemblers from common TableGen description
1448   files.<br><br>
1449
1450   <dt><tt><b>vim/</b></tt> <dd>The <tt>vim</tt> directory contains
1451   syntax-highlighting files which will work with the VIM editor, providing
1452   syntax highlighting support for LLVM assembly files and TableGen
1453   description files. For information on how to use the syntax files, consult
1454   the <tt>README</tt> file in that directory.<br><br>
1455
1456 </dl>
1457
1458 </div>
1459
1460 <!-- ======================================================================= -->
1461 <div class="doc_subsection"><a name="win32"><tt>llvm/win32</tt></a></div>
1462 <div class="doc_text">
1463   <p>This directory contains build scripts and project files for use with
1464   Visual C++. This allows developers on Windows to build LLVM without the need
1465   for Cygwin. The contents of this directory should be considered experimental
1466   at this time.
1467   </p>
1468 </div>
1469 <!-- *********************************************************************** -->
1470 <div class="doc_section">
1471   <a name="tutorial">An Example Using the LLVM Tool Chain</a>
1472 </div>
1473 <!-- *********************************************************************** -->
1474
1475 <div class="doc_text">
1476 <p>This section gives an example of using LLVM.  llvm-gcc3 is now obsolete,
1477 so we only include instructions for llvm-gcc4.
1478 </p>
1479
1480 <p><b>Note:</b> The <i>gcc4</i> frontend's invocation is <b><i>considerably different</i></b>
1481 from the previous <i>gcc3</i> frontend. In particular, the <i>gcc4</i> frontend <b><i>does not</i></b>
1482 create bitcode by default: <i>gcc4</i> produces native code. As the example below illustrates,
1483 the '--emit-llvm' flag is needed to produce LLVM bitcode output. For <i>makefiles</i> and
1484 <i>configure</i> scripts, the CFLAGS variable needs '--emit-llvm' to produce bitcode
1485 output.</p>
1486 </div>
1487
1488 <!-- ======================================================================= -->
1489 <div class="doc_subsection"><a name="tutorial4">Example with llvm-gcc4</a></div>
1490
1491 <div class="doc_text">
1492
1493 <ol>
1494   <li><p>First, create a simple C file, name it 'hello.c':</p>
1495
1496 <div class="doc_code">
1497 <pre>
1498 #include &lt;stdio.h&gt;
1499
1500 int main() {
1501   printf("hello world\n");
1502   return 0;
1503 }
1504 </pre></div></li>
1505
1506   <li><p>Next, compile the C file into a native executable:</p>
1507
1508       <div class="doc_code"><pre>% llvm-gcc hello.c -o hello</pre></div>
1509
1510       <p>Note that llvm-gcc works just like GCC by default.  The standard -S and
1511         -c arguments work as usual (producing a native .s or .o file,
1512         respectively).</p></li>
1513
1514   <li><p>Next, compile the C file into a LLVM bitcode file:</p>
1515
1516       <div class="doc_code">
1517       <pre>% llvm-gcc -O3 -emit-llvm hello.c -c -o hello.bc</pre></div>
1518
1519       <p>The -emit-llvm option can be used with the -S or -c options to emit an
1520          LLVM ".ll" or ".bc" file (respectively) for the code.  This allows you
1521          to use the <a href="CommandGuide/index.html">standard LLVM tools</a> on
1522          the bitcode file.</p>
1523
1524       <p>Unlike llvm-gcc3, llvm-gcc4 correctly responds to -O[0123] arguments.
1525          </p></li>
1526
1527   <li><p>Run the program in both forms. To run the program, use:</p>
1528
1529       <div class="doc_code"><pre>% ./hello</pre></div>
1530
1531       <p>and</p>
1532
1533       <div class="doc_code"><pre>% lli hello.bc</pre></div>
1534
1535       <p>The second examples shows how to invoke the LLVM JIT, <a
1536        href="CommandGuide/html/lli.html">lli</a>.</p></li>
1537
1538   <li><p>Use the <tt>llvm-dis</tt> utility to take a look at the LLVM assembly
1539       code:</p>
1540
1541 <div class="doc_code">
1542 <pre>llvm-dis &lt; hello.bc | less</pre>
1543 </div></li>
1544
1545   <li><p>Compile the program to native assembly using the LLC code
1546       generator:</p>
1547
1548       <div class="doc_code"><pre>% llc hello.bc -o hello.s</pre></div></li>
1549
1550   <li><p>Assemble the native assembly language file into a program:</p>
1551
1552 <div class="doc_code">
1553 <pre>
1554 <b>Solaris:</b> % /opt/SUNWspro/bin/cc -xarch=v9 hello.s -o hello.native
1555
1556 <b>Others:</b>  % gcc hello.s -o hello.native
1557 </pre>
1558 </div></li>
1559
1560   <li><p>Execute the native code program:</p>
1561
1562       <div class="doc_code"><pre>% ./hello.native</pre></div>
1563
1564       <p>Note that using llvm-gcc to compile directly to native code (i.e. when
1565          the -emit-llvm option is not present) does steps 6/7/8 for you.</p>
1566         </li>
1567
1568 </ol>
1569
1570 </div>
1571
1572
1573 <!-- *********************************************************************** -->
1574 <div class="doc_section">
1575   <a name="problems">Common Problems</a>
1576 </div>
1577 <!-- *********************************************************************** -->
1578
1579 <div class="doc_text">
1580
1581 <p>If you are having problems building or using LLVM, or if you have any other
1582 general questions about LLVM, please consult the <a href="FAQ.html">Frequently
1583 Asked Questions</a> page.</p>
1584
1585 </div>
1586
1587 <!-- *********************************************************************** -->
1588 <div class="doc_section">
1589   <a name="links">Links</a>
1590 </div>
1591 <!-- *********************************************************************** -->
1592
1593 <div class="doc_text">
1594
1595 <p>This document is just an <b>introduction</b> on how to use LLVM to do
1596 some simple things... there are many more interesting and complicated things
1597 that you can do that aren't documented here (but we'll gladly accept a patch
1598 if you want to write something up!).  For more information about LLVM, check
1599 out:</p>
1600
1601 <ul>
1602   <li><a href="http://llvm.org/">LLVM homepage</a></li>
1603   <li><a href="http://llvm.org/doxygen/">LLVM doxygen tree</a></li>
1604   <li><a href="http://llvm.org/docs/Projects.html">Starting a Project
1605   that Uses LLVM</a></li>
1606 </ul>
1607
1608 </div>
1609
1610 <!-- *********************************************************************** -->
1611
1612 <hr>
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1618
1619   <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
1620   <a href="http://llvm.x10sys.com/rspencer/">Reid Spencer</a><br>
1621   <a href="http://llvm.org">The LLVM Compiler Infrastructure</a><br>
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