1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd"> 2<html> 3<head> 4 <title>Using The LLVM Libraries</title> 5 <link rel="stylesheet" href="llvm.css" type="text/css"> 6</head> 7<body> 8<h1>Using The LLVM Libraries</h1> 9<ol> 10 <li><a href="#abstract">Abstract</a></li> 11 <li><a href="#introduction">Introduction</a></li> 12 <li><a href="#descriptions">Library Descriptions</a></li> 13 <li><a href="#dependencies">Library Dependencies</a></li> 14 <li><a href="#rot">Linkage Rules Of Thumb</a> 15 <ol> 16 <li><a href="#always">Always link LLVMCore, LLVMSupport, LLVMSystem</a> 17 <li><a href="#onlyone">Never link both archive and re-linked</a> 18 </ol> 19 </li> 20</ol> 21 22<div class="doc_author"> 23 <p>Written by <a href="mailto:rspencer@x10sys.com">Reid Spencer</a></p> 24</div> 25 26<p class="doc_warning">Warning: This document is out of date, for more 27 information please 28 see <a href="CommandGuide/html/llvm-config.html">llvm-config</a> or, 29 if you use CMake, <a href="CMake.html#embedding">the CMake LLVM 30 guide</a>.</p> 31 32<!-- ======================================================================= --> 33<h2><a name="abstract">Abstract</a></h2> 34<div> 35 <p>Amongst other things, LLVM is a toolkit for building compilers, linkers, 36 runtime executives, virtual machines, and other program execution related 37 tools. In addition to the LLVM tool set, the functionality of LLVM is 38 available through a set of libraries. To use LLVM as a toolkit for 39 constructing tools, a developer needs to understand what is contained in the 40 various libraries, what they depend on, and how to use them. Fortunately, 41 there is a tool, <tt>llvm-config</tt> to aid with this. This document 42 describes the contents of the libraries and how to use <tt>llvm-config</tt> 43 to generate command line options. 44</p> 45</div> 46 47<!-- ======================================================================= --> 48<h2><a name="introduction">Introduction</a></h2> 49<div> 50 <p>If you're writing a compiler, virtual machine, or any other utility based 51 on LLVM, you'll need to figure out which of the many libraries files you will 52 need to link with to be successful. An understanding of the contents of these 53 libraries will be useful in coming up with an optimal specification for the 54 libraries to link with. The purpose of this document is to reduce some of 55 the trial and error that the author experienced in using LLVM.</p> 56 <p>LLVM produces two types of libraries: archives (ending in <tt>.a</tt>) and 57 objects (ending in <tt>.o</tt>). However, both are libraries. Libraries ending 58 in <tt>.o</tt> are known as re-linked libraries because they contain all the 59 compilation units of the library linked together as a single <tt>.o</tt> file. 60 Furthermore, several of the libraries have <em>both</em> forms of library. The 61 re-linked libraries are used whenever you want to include all symbols from the 62 library. The archive libraries are used whenever you want to only resolve 63 outstanding symbols at that point in the link without including everything in 64 the library. </p> 65 <p>If you're using the LLVM Makefile system to link your tools,you will use 66 the <tt>LLVMLIBS</tt> make variable. 67 (see the <a href="MakefileGuide.html#LLVMLIBS">Makefile Guide</a> for 68 details). This variable specifies which LLVM libraries to link into your tool 69 and the order in which they will be linked. You specify re-linked libraries by 70 naming the library without a suffix. You specify archive libraries by naming 71 the library with a <tt>.a</tt> suffix but without the <tt>lib</tt> prefix. The 72 order in which the libraries appear in the <tt>LLVMLIBS</tt> variable 73 definition is the order in which they will be linked. Getting this order 74 correct for your tool can sometimes be challenging. 75</div> 76<!-- ======================================================================= --> 77<h2><a name="descriptions">Library Descriptions</a></h2> 78<div> 79 <p>The table below categorizes each library 80<table style="text-align:left"> 81 <tr><th>Library</th><th>Forms</th><th>Description</th></tr> 82 <tr><th colspan="3">Core Libraries</th></tr> 83 <tr><td>LLVMArchive</td><td><tt>.a</tt></td> 84 <td>LLVM archive reading and writing</td></tr> 85 <tr><td>LLVMAsmParser</td><td><tt>.a</tt></td> 86 <td>LLVM assembly parsing</td></tr> 87 <tr><td>LLVMBCReader</td><td><tt>.a</tt></td> 88 <td>LLVM bitcode reading</td></tr> 89 <tr><td>LLVMBCWriter</td><td><tt>.a</tt></td> 90 <td>LLVM bitcode writing</td></tr> 91 <tr><td>LLVMCore</td><td><tt>.a</tt></td> 92 <td>LLVM core intermediate representation</td></tr> 93 <tr><td>LLVMDebugger</td><td><tt>.a</tt></td> 94 <td>Source level debugging support</td></tr> 95 <tr><td>LLVMLinker</td><td><tt>.a</tt></td> 96 <td>Bitcode and archive linking interface</td></tr> 97 <tr><td>LLVMSupport</td><td><tt>.a</tt></td> 98 <td>General support utilities</td></tr> 99 <tr><td>LLVMSystem</td><td><tt>.a</tt></td> 100 <td>Operating system abstraction layer</td></tr> 101 <tr><td>LLVMbzip2</td><td><tt>.a</tt></td> 102 <td>BZip2 compression library</td></tr> 103 104 <tr><th colspan="3">Analysis Libraries</th></tr> 105 <tr><td>LLVMAnalysis</td><td><tt>.a</tt></td> 106 <td>Various analysis passes.</td></tr> 107 <tr><td>LLVMDataStructure</td><td><tt>.o</tt></td> 108 <td>Data structure analysis passes.</td></tr> 109 <tr><td>LLVMipa</td><td><tt>.a</tt></td> 110 <td>Inter-procedural analysis passes.</td></tr> 111 112 <tr><th colspan="3">Transformation Libraries</th></tr> 113 <tr><td>LLVMInstrumentation</td><td><tt>.a</tt></td> 114 <td>Instrumentation passes.</td></tr> 115 <tr><td>LLVMipo</td><td><tt>.a</tt></td> 116 <td>All inter-procedural optimization passes.</td></tr> 117 <tr><td>LLVMScalarOpts</td><td><tt>.a</tt></td> 118 <td>All scalar optimization passes.</td></tr> 119 <tr><td>LLVMTransformUtils</td><td><tt>.a</tt></td> 120 <td>Transformation utilities used by many passes.</td></tr> 121 122 <tr><th colspan="3">Code Generation Libraries </th></tr> 123 <tr><td>LLVMCodeGen</td><td><tt>.o</tt></td> 124 <td>Native code generation infrastructure</td></tr> 125 <tr><td>LLVMSelectionDAG</td><td><tt>.o</tt></td> 126 <td>Aggressive instruction selector for directed acyclic graphs</td></tr> 127 128 <tr><th colspan="3">Target Libraries</th></tr> 129 <tr><td>LLVMAlpha</td><td><tt>.o</tt></td> 130 <td>Code generation for Alpha architecture</td></tr> 131 <tr><td>LLVMARM</td><td><tt>.o</tt></td> 132 <td>Code generation for ARM architecture</td></tr> 133 <tr><td>LLVMCBackend</td><td><tt>.o</tt></td> 134 <td>'C' language code generator.</td></tr> 135 <tr><td>LLVMPowerPC</td><td><tt>.o</tt></td> 136 <td>Code generation for PowerPC architecture</td></tr> 137 <tr><td>LLVMSparc</td><td><tt>.o</tt></td> 138 <td>Code generation for Sparc architecture</td></tr> 139 <tr><td>LLVMTarget</td><td><tt>.a</tt></td> 140 <td>Generic code generation utilities.</td></tr> 141 <tr><td>LLVMX86</td><td><tt>.o</tt></td> 142 <td>Code generation for Intel x86 architecture</td></tr> 143 144 <tr><th colspan="3">Runtime Libraries</th></tr> 145 <tr><td>LLVMInterpreter</td><td><tt>.o</tt></td> 146 <td>Bitcode Interpreter</td></tr> 147 <tr><td>LLVMJIT</td><td><tt>.o</tt></td> 148 <td>Bitcode JIT Compiler</td></tr> 149 <tr><td>LLVMExecutionEngine</td><td><tt>.o</tt></td> 150 <td>Virtual machine engine</td></tr> 151</table> 152</div> 153 154<!-- ======================================================================= --> 155<h2><a name="dependencies">Using llvm-config</a></h2> 156<div> 157 <p>The <tt>llvm-config</tt> tool is a perl script that produces on its output 158 various kinds of information. For example, the source or object directories 159 used to build LLVM can be accessed by passing options to <tt>llvm-config</tt>. 160 For complete details on this tool, please see the 161 <a href="CommandGuide/html/llvm-config.html">manual page</a>.</p> 162 <p>To understand the relationships between libraries, the <tt>llvm-config</tt> 163 can be very useful. If all you know is that you want certain libraries to 164 be available, you can generate the complete set of libraries to link with 165 using one of four options, as below:</p> 166 <ol> 167 <li><tt>--ldflags</tt>. This generates the command line options necessary to 168 be passed to the <tt>ld</tt> tool in order to link with LLVM. Most notably, 169 the <tt>-L</tt> option is provided to specify a library search directory 170 that contains the LLVM libraries.</li> 171 <li><tt>--libs</tt>. This generates command line options suitable for 172 use with a gcc-style linker. That is, libraries are given with a -l option 173 and object files are given with a full path.</li> 174 <li><tt>--libnames</tt>. This generates a list of just the library file 175 names. If you know the directory in which these files reside (see --ldflags) 176 then you can find the libraries there.</li> 177 <li><tt>--libfiles</tt>. This generates the full path names of the 178 LLVM library files.</li> 179 </ol> 180 <p>If you wish to delve further into how <tt>llvm-config</tt> generates the 181 correct order (based on library dependencies), please see the tool named 182 <tt>GenLibDeps.pl</tt> in the <tt>utils</tt> source directory of LLVM.</p> 183 184 <!-- =======NOTE: =========================================================--> 185 <!-- === The following graphs and <dl> list are generated automatically ===--> 186 <!-- === by the util named GenLibDeps.pl in the llvm/utils directory. ===--> 187 <!-- === This should be updated whenever new libraries are added, ===--> 188 <!-- === removed, or changed ===--> 189 <!-- =======NOTE: =========================================================--> 190 <h3>Dependency Relationships Of Libraries</h3> 191 <p>This graph shows the dependency of archive libraries on other archive 192 libraries or objects. Where a library has both archive and object forms, only 193 the archive form is shown.</p> 194 <img src="img/libdeps.gif" alt="Library Dependencies"> 195 <h3>Dependency Relationships Of Object Files</h3> 196 <p>This graph shows the dependency of object files on archive libraries or 197 other objects. Where a library has both object and archive forms, only the 198 dependency to the archive form is shown.</p> 199 <img src="img/objdeps.gif" alt="Object File Dependencies"> 200 <p>The following list shows the dependency relationships between libraries in 201 textual form. The information is the same as shown on the graphs but arranged 202 alphabetically.</p> 203<dl> 204 <dt><b>libLLVMAnalysis.a</b></dt><dd><ul> 205 <li>libLLVMCore.a</li> 206 <li>libLLVMSupport.a</li> 207 <li>libLLVMSystem.a</li> 208 <li>libLLVMTarget.a</li> 209 </ul></dd> 210 <dt><b>libLLVMArchive.a</b></dt><dd><ul> 211 <li>libLLVMBCReader.a</li> 212 <li>libLLVMCore.a</li> 213 <li>libLLVMSupport.a</li> 214 <li>libLLVMSystem.a</li> 215 </ul></dd> 216 <dt><b>libLLVMAsmParser.a</b></dt><dd><ul> 217 <li>libLLVMCore.a</li> 218 <li>libLLVMSystem.a</li> 219 </ul></dd> 220 <dt><b>libLLVMBCReader.a</b></dt><dd><ul> 221 <li>libLLVMCore.a</li> 222 <li>libLLVMSupport.a</li> 223 <li>libLLVMSystem.a</li> 224 </ul></dd> 225 <dt><b>libLLVMBCWriter.a</b></dt><dd><ul> 226 <li>libLLVMCore.a</li> 227 <li>libLLVMSupport.a</li> 228 <li>libLLVMSystem.a</li> 229 </ul></dd> 230 <dt><b>libLLVMCodeGen.a</b></dt><dd><ul> 231 <li>libLLVMAnalysis.a</li> 232 <li>libLLVMCore.a</li> 233 <li>libLLVMScalarOpts.a</li> 234 <li>libLLVMSupport.a</li> 235 <li>libLLVMSystem.a</li> 236 <li>libLLVMTarget.a</li> 237 <li>libLLVMTransformUtils.a</li> 238 </ul></dd> 239 <dt><b>libLLVMCore.a</b></dt><dd><ul> 240 <li>libLLVMSupport.a</li> 241 <li>libLLVMSystem.a</li> 242 </ul></dd> 243 <dt><b>libLLVMDebugger.a</b></dt><dd><ul> 244 <li>libLLVMBCReader.a</li> 245 <li>libLLVMCore.a</li> 246 <li>libLLVMSupport.a</li> 247 <li>libLLVMSystem.a</li> 248 </ul></dd> 249 <dt><b>libLLVMInstrumentation.a</b></dt><dd><ul> 250 <li>libLLVMCore.a</li> 251 <li>libLLVMScalarOpts.a</li> 252 <li>libLLVMSupport.a</li> 253 <li>libLLVMTransformUtils.a</li> 254 </ul></dd> 255 <dt><b>libLLVMLinker.a</b></dt><dd><ul> 256 <li>libLLVMArchive.a</li> 257 <li>libLLVMBCReader.a</li> 258 <li>libLLVMCore.a</li> 259 <li>libLLVMSupport.a</li> 260 <li>libLLVMSystem.a</li> 261 </ul></dd> 262 <dt><b>libLLVMScalarOpts.a</b></dt><dd><ul> 263 <li>libLLVMAnalysis.a</li> 264 <li>libLLVMCore.a</li> 265 <li>libLLVMSupport.a</li> 266 <li>libLLVMSystem.a</li> 267 <li>libLLVMTarget.a</li> 268 <li>libLLVMTransformUtils.a</li> 269 </ul></dd> 270 <dt><b>libLLVMSelectionDAG.a</b></dt><dd><ul> 271 <li>libLLVMAnalysis.a</li> 272 <li>libLLVMCodeGen.a</li> 273 <li>libLLVMCore.a</li> 274 <li>libLLVMSupport.a</li> 275 <li>libLLVMSystem.a</li> 276 <li>libLLVMTarget.a</li> 277 <li>libLLVMTransformUtils.a</li> 278 </ul></dd> 279 <dt><b>libLLVMSupport.a</b></dt><dd><ul> 280 <li>libLLVMSystem.a</li> 281 <li>libLLVMbzip2.a</li> 282 </ul></dd> 283 <dt><b>libLLVMSystem.a</b></dt><dd> 284 </dd> 285 <dt><b>libLLVMTarget.a</b></dt><dd><ul> 286 <li>libLLVMCore.a</li> 287 <li>libLLVMSupport.a</li> 288 <li>libLLVMSystem.a</li> 289 </ul></dd> 290 <dt><b>libLLVMTransformUtils.a</b></dt><dd><ul> 291 <li>libLLVMAnalysis.a</li> 292 <li>libLLVMCore.a</li> 293 <li>libLLVMSupport.a</li> 294 <li>libLLVMSystem.a</li> 295 <li>libLLVMTarget.a</li> 296 <li>libLLVMipa.a</li> 297 </ul></dd> 298 <dt><b>libLLVMbzip2.a</b></dt><dd> 299 </dd> 300 <dt><b>libLLVMipa.a</b></dt><dd><ul> 301 <li>libLLVMAnalysis.a</li> 302 <li>libLLVMCore.a</li> 303 <li>libLLVMSupport.a</li> 304 <li>libLLVMSystem.a</li> 305 </ul></dd> 306 <dt><b>libLLVMipo.a</b></dt><dd><ul> 307 <li>libLLVMAnalysis.a</li> 308 <li>libLLVMCore.a</li> 309 <li>libLLVMSupport.a</li> 310 <li>libLLVMSystem.a</li> 311 <li>libLLVMTarget.a</li> 312 <li>libLLVMTransformUtils.a</li> 313 <li>libLLVMipa.a</li> 314 </ul></dd> 315 <dt><b>libLLVMlto.a</b></dt><dd><ul> 316 <li>libLLVMAnalysis.a</li> 317 <li>libLLVMBCReader.a</li> 318 <li>libLLVMBCWriter.a</li> 319 <li>libLLVMCore.a</li> 320 <li>libLLVMLinker.a</li> 321 <li>libLLVMScalarOpts.a</li> 322 <li>libLLVMSupport.a</li> 323 <li>libLLVMSystem.a</li> 324 <li>libLLVMTarget.a</li> 325 <li>libLLVMipa.a</li> 326 <li>libLLVMipo.a</li> 327 </ul></dd> 328 <dt><b>LLVMARM.o</b></dt><dd><ul> 329 <li>libLLVMCodeGen.a</li> 330 <li>libLLVMCore.a</li> 331 <li>libLLVMSelectionDAG.a</li> 332 <li>libLLVMSupport.a</li> 333 <li>libLLVMSystem.a</li> 334 <li>libLLVMTarget.a</li> 335 </ul></dd> 336 <dt><b>LLVMAlpha.o</b></dt><dd><ul> 337 <li>libLLVMCodeGen.a</li> 338 <li>libLLVMCore.a</li> 339 <li>libLLVMSelectionDAG.a</li> 340 <li>libLLVMSupport.a</li> 341 <li>libLLVMSystem.a</li> 342 <li>libLLVMTarget.a</li> 343 </ul></dd> 344 <dt><b>LLVMCBackend.o</b></dt><dd><ul> 345 <li>libLLVMAnalysis.a</li> 346 <li>libLLVMCodeGen.a</li> 347 <li>libLLVMCore.a</li> 348 <li>libLLVMScalarOpts.a</li> 349 <li>libLLVMSupport.a</li> 350 <li>libLLVMSystem.a</li> 351 <li>libLLVMTarget.a</li> 352 <li>libLLVMTransformUtils.a</li> 353 <li>libLLVMipa.a</li> 354 </ul></dd> 355 <dt><b>LLVMExecutionEngine.o</b></dt><dd><ul> 356 <li>libLLVMCore.a</li> 357 <li>libLLVMSupport.a</li> 358 <li>libLLVMSystem.a</li> 359 <li>libLLVMTarget.a</li> 360 </ul></dd> 361 <dt><b>LLVMInterpreter.o</b></dt><dd><ul> 362 <li>LLVMExecutionEngine.o</li> 363 <li>libLLVMCodeGen.a</li> 364 <li>libLLVMCore.a</li> 365 <li>libLLVMSupport.a</li> 366 <li>libLLVMSystem.a</li> 367 <li>libLLVMTarget.a</li> 368 </ul></dd> 369 <dt><b>LLVMJIT.o</b></dt><dd><ul> 370 <li>LLVMExecutionEngine.o</li> 371 <li>libLLVMCore.a</li> 372 <li>libLLVMSupport.a</li> 373 <li>libLLVMSystem.a</li> 374 <li>libLLVMTarget.a</li> 375 </ul></dd> 376 <dt><b>LLVMPowerPC.o</b></dt><dd><ul> 377 <li>libLLVMCodeGen.a</li> 378 <li>libLLVMCore.a</li> 379 <li>libLLVMSelectionDAG.a</li> 380 <li>libLLVMSupport.a</li> 381 <li>libLLVMSystem.a</li> 382 <li>libLLVMTarget.a</li> 383 </ul></dd> 384 <dt><b>LLVMSparc.o</b></dt><dd><ul> 385 <li>libLLVMCodeGen.a</li> 386 <li>libLLVMCore.a</li> 387 <li>libLLVMSelectionDAG.a</li> 388 <li>libLLVMSupport.a</li> 389 <li>libLLVMSystem.a</li> 390 <li>libLLVMTarget.a</li> 391 </ul></dd> 392 <dt><b>LLVMX86.o</b></dt><dd><ul> 393 <li>libLLVMCodeGen.a</li> 394 <li>libLLVMCore.a</li> 395 <li>libLLVMSelectionDAG.a</li> 396 <li>libLLVMSupport.a</li> 397 <li>libLLVMSystem.a</li> 398 <li>libLLVMTarget.a</li> 399 </ul></dd> 400</dl> 401</div> 402 403<!-- ======================================================================= --> 404<h2><a name="rot">Linkage Rules Of Thumb</a></h2> 405<div> 406 <p>This section contains various "rules of thumb" about what files you 407 should link into your programs.</p> 408<!-- ======================================================================= --> 409<h3> 410 <a name="always">Always Link LLVMCore, LLVMSupport, and LLVMSystem</a> 411</h3> 412<div> 413 <p>No matter what you do with LLVM, the last three entries in the value of 414 your LLVMLIBS make variable should always be: 415 <tt>LLVMCore LLVMSupport.a LLVMSystem.a</tt>. There are no <tt>LLVM</tt> 416 programs that don't depend on these three.</p> 417</div> 418<!-- ======================================================================= --> 419<h3> 420 <a name="onlyone">Never link both archive and re-linked library</a> 421</h3> 422<div> 423 <p>There is never any point to linking both the re-linked (<tt>.o</tt>) and 424 the archive (<tt>.a</tt>) versions of a library. Since the re-linked version 425 includes the entire library, the archive version will not resolve any symbols. 426 You could even end up with link error if you place the archive version before 427 the re-linked version on the linker's command line.</p> 428</div> 429 430</div> 431 432<!-- ======================================================================= --> 433<hr> 434<div class="doc_footer"> 435<address> 436 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img 437 src="http://jigsaw.w3.org/css-validator/images/vcss-blue" alt="Valid CSS"></a> 438 <a href="http://validator.w3.org/check/referer"><img 439 src="http://www.w3.org/Icons/valid-html401-blue" alt="Valid HTML 4.01"></a> 440 <a href="mailto:rspencer@x10sys.com">Reid Spencer</a> 441</address> 442<a href="http://llvm.org/">The LLVM Compiler Infrastructure</a> 443<br>Last modified: $Date: 2011-04-22 20:30:22 -0400 (Fri, 22 Apr 2011) $ </div> 444</body> 445</html> 446<!-- vim: sw=2 ts=2 ai 447--> 448
