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4 <title>Using The LLVM Libraries</title>
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8 <div class="doc_title">Using The LLVM Libraries</div>
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>
16 <li><a href="#always">Always link LLVMCore, LLVMSupport, LLVMSystem</a>
17 <li><a href="#onlyone">Never link both archive and re-linked</a>
22 <div class="doc_author">
23 <p>Written by <a href="mailto:rspencer@x10sys.com">Reid Spencer</a></p>
26 <p class="doc_warning">Warning: This document is out of date, please see <a href="CommandGuide/html/llvm-config.html">llvm-config</a> for more information.</p>
28 <!-- ======================================================================= -->
29 <div class="doc_section"><a name="abstract">Abstract</a></div>
30 <div class="doc_text">
31 <p>Amongst other things, LLVM is a toolkit for building compilers, linkers,
32 runtime executives, virtual machines, and other program execution related
33 tools. In addition to the LLVM tool set, the functionality of LLVM is
34 available through a set of libraries. To use LLVM as a toolkit for
35 constructing tools, a developer needs to understand what is contained in the
36 various libraries, what they depend on, and how to use them. This document
37 describes the contents of the libraries and how and when to use them.
41 <!-- ======================================================================= -->
42 <div class="doc_section"> <a name="introduction">Introduction</a></div>
43 <div class="doc_text">
44 <p>If you're writing a compiler, virtual machine, or any other utility based
45 on LLVM, you'll need to figure out which of the many libraries files you will
46 need to link with to be successful. An understanding of the contents of these
47 files and their inter-relationships will be useful in coming up with an optimal
48 specification for the libraries to link with. The purpose of this document is
49 to reduce some of the trial and error that the author experienced in using
51 <p>LLVM produces two types of libraries: archives (ending in <tt>.a</tt>) and
52 objects (ending in <tt>.o</tt>). However, both are libraries. Libraries ending
53 in <tt>.o</tt> are known as re-linked libraries because they contain all the
54 compilation units of the library linked together as a single <tt>.o</tt> file.
55 Furthermore, many of the libraries have <em>both</em> forms of library. The
56 re-linked libraries are used whenever you want to include all symbols from the
57 library. The archive libraries are used whenever you want to only resolve
58 outstanding symbols at that point in the link without including everything in
60 <p>When linking your tools, you will use the <tt>LLVMLIBS</tt> make variable.
61 (see the <a href="MakefileGuide.html#LLVMLIBS">Makefile Guide</a> for
62 details). This variable specifies which LLVM libraries to link into your tool
63 and the order in which they will be linked. You specify re-linked libraries by
64 naming the library without a suffix. You specify archive libraries by naming
65 the library with a <tt>.a</tt> suffix but without the <tt>lib</tt> prefix. The
66 order in which the libraries appear in the <tt>LLVMLIBS</tt> variable
67 definition is the order in which they will be linked. Getting this order
68 correct for your tool can sometimes be challenging.
70 <!-- ======================================================================= -->
71 <div class="doc_section"><a name="descriptions"></a>Library Descriptions</div>
72 <div class="doc_text">
73 <p>The table below categorizes each library
74 <table style="text-align:left">
75 <tr><th>Library</th><th>Forms</th><th>Description</th></tr>
76 <tr><th colspan="3">Core Libraries</th></tr>
77 <tr><td>LLVMArchive</td><td><tt>.a</tt></td>
78 <td>LLVM archive reading and writing</td></tr>
79 <tr><td>LLVMAsmParser</td><td><tt>.o</tt></td>
80 <td>LLVM assembly parsing</td></tr>
81 <tr><td>LLVMBCReader</td><td><tt>.o</tt></td>
82 <td>LLVM bytecode reading</td></tr>
83 <tr><td>LLVMBCWriter</td><td><tt>.o</tt></td>
84 <td>LLVM bytecode writing</td></tr>
85 <tr><td>LLVMCore</td><td><tt>.o</tt></td>
86 <td>LLVM core intermediate representation</td></tr>
87 <tr><td>LLVMDebugger</td><td><tt>.o</tt></td>
88 <td>Source level debugging support</td></tr>
89 <tr><td>LLVMLinker</td><td><tt>.a</tt></td>
90 <td>Bytecode and archive linking interface</td></tr>
91 <tr><td>LLVMSupport</td><td><tt>.a .o</tt></td>
92 <td>General support utilities</td></tr>
93 <tr><td>LLVMSystem</td><td><tt>.a .o</tt></td>
94 <td>Operating system abstraction layer</td></tr>
96 <tr><th colspan="3">Analysis Libraries</th></tr>
97 <tr><td>LLVMAnalysis</td><td><tt>.a .o</tt></td>
98 <td>Various analysis passes.</td></tr>
99 <tr><td>LLVMDataStructure</td><td><tt>.a .o</tt></td>
100 <td>Data structure analysis passes.</td></tr>
101 <tr><td>LLVMipa</td><td><tt>.a .o</tt></td>
102 <td>Inter-procedural analysis passes.</td></tr>
104 <tr><th colspan="3">Transformation Libraries</th></tr>
105 <tr><td>LLVMInstrumentation</td><td><tt>.a .o</tt></td>
106 <td>Instrumentation passes.</td></tr>
107 <tr><td>LLVMipo</td><td><tt>.a .o</tt></td>
108 <td>All inter-procedural optimization passes.</td></tr>
109 <tr><td>LLVMScalarOpts</td><td><tt>.a .o</tt></td>
110 <td>All scalar optimization passes.</td></tr>
111 <tr><td>LLVMTransforms</td><td><tt>.a .o</tt></td>
112 <td>Uncategorized transformation passes.</td></tr>
113 <tr><td>LLVMTransformUtils</td><td><tt>.a .o</tt></td>
114 <td>Transformation utilities.</td></tr>
116 <tr><th colspan="3">Code Generation Libraries </th></tr>
117 <tr><td>LLVMCodeGen</td><td><tt>.o</tt></td>
118 <td>Native code generation infrastructure</td></tr>
120 <tr><th colspan="3">Target Libraries</th></tr>
121 <tr><td>LLVMAlpha</td><td><tt>.o</tt></td>
122 <td>Code generation for Alpha architecture</td></tr>
123 <tr><td>LLVMCBackend</td><td><tt>.o</tt></td>
124 <td>'C' language code generator.</td></tr>
125 <tr><td>LLVMIA64</td><td><tt>.o</tt></td>
126 <td>Code generation for IA64 architecture</td></tr>
127 <tr><td>LLVMPowerPC</td><td><tt>.o</tt></td>
128 <td>Code generation for PowerPC architecture</td></tr>
129 <tr><td>LLVMSelectionDAG</td><td><tt>.o</tt></td>
130 <td>Aggressive instruction selector for directed acyclic graphs</td></tr>
131 <tr><td>LLVMSparc</td><td><tt>.o</tt></td>
132 <td>Code generation for Sparc architecture</td></tr>
133 <tr><td>LLVMTarget</td><td><tt>.a .o</tt></td>
134 <td>Generic code generation utilities.</td></tr>
135 <tr><td>LLVMX86</td><td><tt>.o</tt></td>
136 <td>Code generation for Intel x86 architecture</td></tr>
138 <tr><th colspan="3">Runtime Libraries</th></tr>
139 <tr><td>LLVMInterpreter</td><td><tt>.o</tt></td>
140 <td>Bytecode Interpreter</td></tr>
141 <tr><td>LLVMJIT</td><td><tt>.o</tt></td>
142 <td>Bytecode JIT Compiler</td></tr>
143 <tr><td>LLVMExecutionEngine</td><td><tt>.o</tt></td>
144 <td>Virtual machine engine</td></tr>
148 <!-- ======================================================================= -->
149 <div class="doc_section"><a name="dependencies"></a>Library Dependencies</div>
150 <div class="doc_text">
151 <p>Below are two dependency graphs and a list that show the relationships
152 between the various LLVM archive libraries and object files. This information
153 can be automatically generated with the <tt>GenLibDeps.pl</tt> utility found
154 in the <tt>llvm/utils</tt> directory.</p>
155 <!-- =======NOTE: =========================================================-->
156 <!-- === The following graphs and <dl> list are generated automatically ===-->
157 <!-- === by the util named GenLibDeps.pl in the llvm/utils directory. ===-->
158 <!-- === This should be updated whenever new libraries are added, ===-->
159 <!-- === removed, or changed ===-->
160 <!-- =======NOTE: =========================================================-->
161 <h2>Dependency Relationships Of Libraries</h2>
162 <p>This graph shows the dependency of archive libraries on other archive
163 libraries or objects. Where a library has both archive and object forms, only
164 the archive form is shown.</p>
165 <img src="img/libdeps.gif" alt="Library Dependencies"/>
166 <h2>Dependency Relationships Of Object Files</h2>
167 <p>This graph shows the dependency of object files on archive libraries or
168 other objects. Where a library has both object and archive forms, only the
169 dependency to the archive form is shown.</p>
170 <img src="img/objdeps.gif" alt="Object File Dependencies"/>
171 <p>The following list shows the dependency relationships between libraries in
172 textual form. The information is the same as shown on the graphs but arranged
175 <dt><b>libLLVMAnalysis.a</b</dt><dd><ul>
176 <li>libLLVMSupport.a</li>
177 <li>libLLVMTarget.a</li>
180 <dt><b>libLLVMArchive.a</b</dt><dd><ul>
181 <li>libLLVMSupport.a</li>
182 <li>libLLVMSystem.a</li>
183 <li>LLVMBCReader.o</li>
186 <dt><b>libLLVMInstrumentation.a</b</dt><dd><ul>
187 <li>libLLVMScalarOpts.a</li>
188 <li>libLLVMSupport.a</li>
189 <li>libLLVMTransformUtils.a</li>
192 <dt><b>libLLVMLinker.a</b</dt><dd><ul>
193 <li>libLLVMArchive.a</li>
194 <li>libLLVMSystem.a</li>
195 <li>LLVMBCReader.o</li>
198 <dt><b>libLLVMScalarOpts.a</b</dt><dd><ul>
199 <li>libLLVMAnalysis.a</li>
200 <li>libLLVMSupport.a</li>
201 <li>libLLVMTarget.a</li>
202 <li>libLLVMTransformUtils.a</li>
205 <dt><b>libLLVMSupport.a</b</dt><dd><ul>
206 <li>libLLVMSystem.a</li>
209 <dt><b>libLLVMSystem.a</b</dt><dd><ul>
211 <dt><b>libLLVMTarget.a</b</dt><dd><ul>
212 <li>libLLVMSupport.a</li>
214 <li>LLVMSelectionDAG.o</li>
216 <dt><b>libLLVMTransformUtils.a</b</dt><dd><ul>
217 <li>libLLVMAnalysis.a</li>
218 <li>libLLVMipa.a</li>
219 <li>libLLVMScalarOpts.a</li>
220 <li>libLLVMSupport.a</li>
223 <dt><b>libLLVMTransforms.a</b</dt><dd><ul>
224 <li>libLLVMSupport.a</li>
225 <li>libLLVMTarget.a</li>
226 <li>libLLVMTransformUtils.a</li>
229 <dt><b>libLLVMipa.a</b</dt><dd><ul>
230 <li>libLLVMAnalysis.a</li>
231 <li>libLLVMSupport.a</li>
234 <dt><b>libLLVMipo.a</b</dt><dd><ul>
235 <li>libLLVMAnalysis.a</li>
236 <li>libLLVMipa.a</li>
237 <li>libLLVMSupport.a</li>
238 <li>libLLVMTarget.a</li>
239 <li>libLLVMTransformUtils.a</li>
242 <dt><b>LLVMAlpha.o</b</dt><dd><ul>
243 <li>libLLVMScalarOpts.a</li>
244 <li>libLLVMSupport.a</li>
245 <li>libLLVMTarget.a</li>
246 <li>LLVMCodeGen.o</li>
248 <li>LLVMSelectionDAG.o</li>
250 <dt><b>LLVMAsmParser.o</b</dt><dd><ul>
253 <dt><b>LLVMBCReader.o</b</dt><dd><ul>
254 <li>libLLVMSupport.a</li>
255 <li>libLLVMSystem.a</li>
258 <dt><b>LLVMBCWriter.o</b</dt><dd><ul>
259 <li>libLLVMSupport.a</li>
262 <dt><b>LLVMCBackend.o</b</dt><dd><ul>
263 <li>libLLVMAnalysis.a</li>
264 <li>libLLVMipa.a</li>
265 <li>libLLVMScalarOpts.a</li>
266 <li>libLLVMSupport.a</li>
267 <li>libLLVMTarget.a</li>
268 <li>LLVMCodeGen.o</li>
271 <dt><b>LLVMCodeGen.o</b</dt><dd><ul>
272 <li>libLLVMAnalysis.a</li>
273 <li>libLLVMSupport.a</li>
274 <li>libLLVMTarget.a</li>
277 <dt><b>LLVMCore.o</b</dt><dd><ul>
278 <li>libLLVMSupport.a</li>
280 <dt><b>LLVMDataStructure.o</b</dt><dd><ul>
281 <li>libLLVMAnalysis.a</li>
282 <li>libLLVMSupport.a</li>
283 <li>libLLVMTarget.a</li>
286 <dt><b>LLVMDebugger.o</b</dt><dd><ul>
287 <li>libLLVMSupport.a</li>
288 <li>libLLVMSystem.a</li>
289 <li>LLVMBCReader.o</li>
292 <dt><b>LLVMExecutionEngine.o</b</dt><dd><ul>
293 <li>libLLVMSupport.a</li>
294 <li>libLLVMSystem.a</li>
295 <li>libLLVMTarget.a</li>
298 <dt><b>LLVMIA64.o</b</dt><dd><ul>
299 <li>libLLVMScalarOpts.a</li>
300 <li>libLLVMSupport.a</li>
301 <li>libLLVMTarget.a</li>
302 <li>LLVMCodeGen.o</li>
304 <li>LLVMSelectionDAG.o</li>
306 <dt><b>LLVMInterpreter.o</b</dt><dd><ul>
307 <li>libLLVMSupport.a</li>
308 <li>libLLVMSystem.a</li>
309 <li>libLLVMTarget.a</li>
311 <li>LLVMExecutionEngine.o</li>
313 <dt><b>LLVMJIT.o</b</dt><dd><ul>
314 <li>libLLVMSupport.a</li>
315 <li>libLLVMSystem.a</li>
316 <li>libLLVMTarget.a</li>
317 <li>LLVMCodeGen.o</li>
319 <li>LLVMExecutionEngine.o</li>
321 <dt><b>LLVMPowerPC.o</b</dt><dd><ul>
322 <li>libLLVMScalarOpts.a</li>
323 <li>libLLVMSupport.a</li>
324 <li>libLLVMTarget.a</li>
325 <li>LLVMCodeGen.o</li>
327 <li>LLVMSelectionDAG.o</li>
329 <dt><b>LLVMSelectionDAG.o</b</dt><dd><ul>
330 <li>libLLVMSupport.a</li>
331 <li>libLLVMSystem.a</li>
332 <li>libLLVMTarget.a</li>
333 <li>libLLVMTransformUtils.a</li>
334 <li>LLVMCodeGen.o</li>
337 <dt><b>LLVMSparc.o</b</dt><dd><ul>
338 <li>libLLVMScalarOpts.a</li>
339 <li>libLLVMSupport.a</li>
340 <li>libLLVMTarget.a</li>
341 <li>LLVMCodeGen.o</li>
343 <li>LLVMSelectionDAG.o</li>
345 <dt><b>LLVMX86.o</b</dt><dd><ul>
346 <li>libLLVMScalarOpts.a</li>
347 <li>libLLVMSupport.a</li>
348 <li>libLLVMTarget.a</li>
349 <li>LLVMCodeGen.o</li>
351 <li>LLVMSelectionDAG.o</li>
353 <dt><b>LLVMbzip2.o</b</dt><dd><ul>
358 <!-- ======================================================================= -->
359 <div class="doc_section"><a name="rot">Linkage Rules Of Thumb</a></div>
360 <div class="doc_text">
361 <p>This section contains various "rules of thumb" about what files you
362 should link into your programs.</p>
364 <!-- ======================================================================= -->
365 <div class="doc_subsection"><a name="always">Always Link LLVMCore, LLVMSupport,
366 and LLVMSystem</a></div>
367 <div class="doc_text">
368 <p>No matter what you do with LLVM, the last three entries in the value of
369 your LLVMLIBS make variable should always be:
370 <tt>LLVMCore LLVMSupport.a LLVMSystem.a</tt>. There are no <tt>LLVM</tt>
371 programs that don't depend on these three.</p>
373 <!-- ======================================================================= -->
374 <div class="doc_subsection"><a name="onlyone">Never link both archive and
375 re-linked library</a></div>
376 <div class="doc_text">
377 <p>There is never any point to linking both the re-linked (<tt>.o</tt>) and
378 the archive (<tt>.a</tt>) versions of a library. Since the re-linked version
379 includes the entire library, the archive version will not resolve any symbols.
380 You could even end up with link error if you place the archive version before
381 the re-linked version on the linker's command line.</p>
383 <!-- ======================================================================= -->
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