Gitiles
Code Review Sign In
gerrit-public.fairphone.software / fp2-dev / platform / external / llvm / 44ac659bc5632d93e349389b4ac1a210bd25928a / . / docs / GettingStarted.html
blob: 96bd877dd0eec4f4076dd66d267133d594effb38 [file] [log] [blame]
Guochun Shif4688a82002-07-17 23:05:56 +0000[diff] [blame]1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
2<html>
3 <head>
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]4 <title>Getting Started with LLVM System</title>
Guochun Shif4688a82002-07-17 23:05:56 +0000[diff] [blame]5 </head>
6
Chris Lattner945de2d2002-07-24 19:59:33 +0000[diff] [blame]7 <body bgcolor=white>
8 <h1>Getting Started with the LLVM System<br><font size=3>By: <a
9 href="mailto:gshi1@uiuc.edu">Guochun Shi</a> and <a
10 href="mailto:sabre@nondot.org">Chris Lattner</a></font></h1>
11
Guochun Shif4688a82002-07-17 23:05:56 +0000[diff] [blame]12 <ul>
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]13 <li><a href="#quickstart">Getting started with LLVM</a>
14 <ol>
15 <li><a href="#cvs">Checkout LLVM from CVS</a>
16 <li><a href="#environment">Set up your environment</a>
17 <li><a href="#compile">Compiling the Source Code</a>
18 </ol>
Guochun Shif4688a82002-07-17 23:05:56 +0000[diff] [blame]19 <li><a href="#layout">Program layout</a>
20 <ol>
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]21 <li><a href="#cvsdir">CVS directories</a>
Chris Lattner44ac6592002-08-09 16:14:56 +0000[diff] [blame^]22 <li><a href="#dd"><tt>Depend</tt>, <tt>Debug</tt>, &amp;
23 <tt>Release</tt> directories</a></li>
24 <li><a href="#include"><tt>llvm/include</tt></a>
25 <li><a href="#lib"><tt>llvm/lib</tt></a>
26 <li><a href="#test"><tt>llvm/test</tt></a>
27 <li><a href="#tools"><tt>llvm/tools</tt></a>
Guochun Shif4688a82002-07-17 23:05:56 +0000[diff] [blame]28 </ol>
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]29 <li><a href="#tutorial">An example using the LLVM tool chain</a>
Guochun Shif4688a82002-07-17 23:05:56 +0000[diff] [blame]30 <li><a href="#links">Links</a>
31 </ul>
Guochun Shif4688a82002-07-17 23:05:56 +0000[diff] [blame]32
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]33
34
35 <!--=====================================================================-->
36 <h2><a name="quickstart">Getting Started with LLVM</a></h2>
37 <!--=====================================================================-->
38
39 <p>This guide is meant to get you up and running with LLVM as quickly as
40 possible. Once you get the basic system running you can choose an area to
41 dive into and learn more about. If you get stuck or something is missing
42 from this document, please email <a
43 href="mailto:sabre@nondot.org">Chris</a>.</p>
44
45
46 <!------------------------------------------------------------------------->
47 <h3><a name="tools">Checkout LLVM from CVS</a></h3>
48 <!------------------------------------------------------------------------->
49
50 <p>First step is to get the actual source code. To do this, all you need to
51 do is check it out from CVS. From your home directory, just enter:</p>
52
Chris Lattner44ac6592002-08-09 16:14:56 +0000[diff] [blame^]53 <p><tt>cvs -d /home/vadve/vadve/Research/DynOpt/CVSRepository checkout
54 llvm</tt></p>
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]55
Chris Lattner44ac6592002-08-09 16:14:56 +0000[diff] [blame^]56 <p>This will create an '<tt>llvm</tt>' directory in your home directory and
57 fully populate it with the source code for LLVM.</p>
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]58
59
60 <!------------------------------------------------------------------------->
61 <h3><a name="tools">Set up your environment</a></h3>
62 <!------------------------------------------------------------------------->
63
64 <p>Now that you have the source code available, you should set up your
65 environment to be able to use the LLVM tools (once compiled) with as little
66 hassle as possible. To do this, we recommend that you add the following
67 lines to your <tt>.cshrc</tt> (or the corresponding lines to your
68 <tt>.profile</tt> if you use a bourne shell derivative):
69
70 <pre>
71 # Make the C frontend easy to use...
72 alias llvmgcc /home/vadve/lattner/cvs/gcc_install/bin/gcc
73
74 # Make the LLVM tools easy to use...
75 setenv PATH ~/llvm/tools/Debug:${PATH}
76 </pre>
77
78 <p>The C compiler is not included in the CVS tree you just checked out, so
79 we just point to the cannonical location, and access it with the
80 <tt>llvmgcc</tt> command. The rest of the <a href="#tools">LLVM tools</a>
Chris Lattner44ac6592002-08-09 16:14:56 +0000[diff] [blame^]81 will be built into the <tt>llvm/tools/Debug</tt> directory inside of the
82 sourcebase. Adding them to your path will make it much easier to use
83 them.</p>
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]84
85
86
87 <!------------------------------------------------------------------------->
88 <h3><a name="compile">Compiling the Source Code</a></h3>
89 <!------------------------------------------------------------------------->
90
91 <p>Every directory in the LLVM source tree includes a Makefile to build it,
92 and any subdirectories that it contains. These makefiles require that you
93 use <tt>gmake</tt>, instead of <tt>make</tt> to build them, but can
94 otherwise be used freely. To build the entire LLVM system, just enter the
95 top level <tt>llvm</tt> directory and type <tt>gmake</tt>. A few minutes
96 later you will hopefully have a freshly compiled toolchain waiting for you
97 in <tt>llvm/tools/Debug</tt>. If you want to look at the libraries that
98 were compiled, look in <tt>llvm/lib/Debug</tt>.</p>
99
Chris Lattner44ac6592002-08-09 16:14:56 +0000[diff] [blame^]100 <p>By default, the LLVM build process sends all temporary (<tt>.o</tt>,
101 <tt>.so</tt>, <tt>.a</tt>) files into a <tt>/shared/[your login
102 name]/...</tt> directory, which is supposed to be on a disk local to the
103 current machine. If you get an error talking about a <tt>/shared</tt>
104 directory, and you find out that it doesn't exist, try enabling the
105 "<tt>BUILD_ROOT = .</tt> line in the top level <tt>Makefile.common</tt> that
106 will change LLVM to build into the current directory instead of
107 <tt>/shared</tt>.<p>
108
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]109
110 <!--=====================================================================-->
111 <h2><a name="layout">Program Layout</a></h2>
112 <!--=====================================================================-->
113
Chris Lattner44ac6592002-08-09 16:14:56 +0000[diff] [blame^]114 <p>One useful source of infomation about the LLVM sourcebase is the LLVM <a
115 href="http://www.doxygen.org">doxygen</a> documentation, available at <tt><a
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]116 href="http://llvm.cs.uiuc.edu/doxygen/">http://llvm.cs.uiuc.edu/doxygen/</a></tt>. The
117 following is a brief introduction to code layout:</p>
118
119
120 <!------------------------------------------------------------------------->
Chris Lattner44ac6592002-08-09 16:14:56 +0000[diff] [blame^]121 <h3><a name="cvsdir"><tt>CVS</tt> directories</a></h3>
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]122 <!------------------------------------------------------------------------->
123
Chris Lattner44ac6592002-08-09 16:14:56 +0000[diff] [blame^]124 Every directory checked out of CVS will contain a <tt>CVS</tt> directory,
125 for the most part these can just be ignored.
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]126
127
128 <!------------------------------------------------------------------------->
Chris Lattner44ac6592002-08-09 16:14:56 +0000[diff] [blame^]129 <h3><a name="ddr"><tt>Depend</tt>, <tt>Debug</tt>, &amp; <tt>Release</tt>
130 directories</a></h3>
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]131 <!------------------------------------------------------------------------->
132
Chris Lattner44ac6592002-08-09 16:14:56 +0000[diff] [blame^]133 If you are building with the "<tt>BUILD_ROOT=.</tt>" option enabled in the
134 <tt>Makefile.common</tt> file, most source directories will contain two
135 directories, <tt>Depend</tt> and <tt>Debug</tt>. The <tt>Depend</tt>
136 directory contains automatically generated dependance files which are used
137 during compilation to make sure that source files get rebuilt if a header
138 file they use is modified. The <tt>Debug</tt> directory holds the object
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]139 files, library files and executables that are used for building a debug
Chris Lattner44ac6592002-08-09 16:14:56 +0000[diff] [blame^]140 enabled build. The <tt>Release</tt> directory is created to hold the same
141 files when the <tt>ENABLE_OPTIMIZED=1</tt> flag is passed to <tt>gmake</tt>,
142 causing an optimized built to be performed.<p>
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]143
144
145 <!------------------------------------------------------------------------->
Chris Lattner44ac6592002-08-09 16:14:56 +0000[diff] [blame^]146 <h3><a name="include"><tt>llvm/include</tt></a></h3>
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]147 <!------------------------------------------------------------------------->
148
149 This directory contains public header files exported from the LLVM
Chris Lattner44ac6592002-08-09 16:14:56 +0000[diff] [blame^]150 library. The two main subdirectories of this directory are:<p>
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]151
152 <ol>
153 <li><tt>llvm/include/llvm</tt> - This directory contains all of the LLVM
154 specific header files. This directory also has subdirectories for
155 different portions of llvm: <tt>Analysis</tt>, <tt>CodeGen</tt>,
156 <tt>Reoptimizer</tt>, <tt>Target</tt>, <tt>Transforms</tt>, etc...
157
158 <li><tt>llvm/include/Support</tt> - This directory contains generic
159 support libraries that are independant of LLVM, but are used by LLVM.
160 For example, some C++ STL utilities and a Command Line option processing
161 library.
162 </ol>
163
164 <!------------------------------------------------------------------------->
Chris Lattner44ac6592002-08-09 16:14:56 +0000[diff] [blame^]165 <h3><a name="lib"><tt>llvm/lib</tt></a></h3>
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]166 <!------------------------------------------------------------------------->
167
168 This directory contains most source files of LLVM system. In LLVM almost all
169 code exists in libraries, making it very easy to share code among the
170 different <a href="#tools">tools</a>.<p>
171
172 <dl compact>
173 <dt><tt>llvm/lib/VMCore/</tt><dd> This directory holds the core LLVM
174 source files that implement core classes like Instruction and BasicBlock.
175
176 <dt><tt>llvm/lib/AsmParser/</tt><dd> This directory holds the source code
177 for the LLVM assembly language parser library.
178
179 <dt><tt>llvm/lib/ByteCode/</tt><dd> This directory holds code for reading
180 and write LLVM bytecode.
181
182 <dt><tt>llvm/lib/CWrite/</tt><dd> This directory implements the LLVM to C
183 converter.
184
185 <dt><tt>llvm/lib/Analysis/</tt><dd> This directory contains a variety of
186 different program analyses, such as Dominator Information, Call Graphs,
187 Induction Variables, Interval Identification, Natural Loop Identification,
188 etc...
189
190 <dt><tt>llvm/lib/Transforms/</tt><dd> This directory contains the source
191 code for the LLVM to LLVM program transformations, such as Aggressive Dead
192 Code Elimination, Sparse Conditional Constant Propogation, Inlining, Loop
193 Invarient Code Motion, Dead Global Elimination, Pool Allocation, and many
194 others...
195
196 <dt><tt>llvm/lib/Target/</tt><dd> This directory contains files that
197 describe various target architectures for code generation. For example,
198 the llvm/lib/Target/Sparc directory holds the Sparc machine
199 description.<br>
200
201 <dt><tt>llvm/lib/CodeGen/</tt><dd> This directory contains the major parts
202 of the code generator: Instruction Selector, Instruction Scheduling, and
203 Register Allocation.
204
205 <dt><tt>llvm/lib/Reoptimizer/</tt><dd> This directory holds code related
206 to the runtime reoptimizer framework that is currently under development.
207
208 <dt><tt>llvm/lib/Support/</tt><dd> This directory contains the source code
209 that corresponds to the header files located in
210 <tt>llvm/include/Support/</tt>.
211 </dl>
212
213 <!------------------------------------------------------------------------->
Chris Lattner44ac6592002-08-09 16:14:56 +0000[diff] [blame^]214 <h3><a name="test"><tt>llvm/test</tt></a></h3>
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]215 <!------------------------------------------------------------------------->
216
217 <p>This directory contains regression tests and source code that is used to
218 test the LLVM infrastructure...</p>
219
220 <!------------------------------------------------------------------------->
Chris Lattner44ac6592002-08-09 16:14:56 +0000[diff] [blame^]221 <h3><a name="tools"><tt>llvm/tools</tt></a></h3>
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]222 <!------------------------------------------------------------------------->
223
224 <p>The <b>tools</b> directory contains the executables built out of the
225 libraries above, which form the main part of the user interface. You can
226 always get help for a tool by typing <tt>tool_name --help</tt>. The
227 following is a brief introduction to the most important tools.</p>
228
229 <dl compact>
230 <dt><tt><b>as</b></tt><dd>The assembler transforms the human readable
231 llvm assembly to llvm bytecode.<p>
232
233 <dt><tt><b>dis</b></tt><dd>The disassembler transforms the llvm bytecode
234 to human readable llvm assembly. Additionally it can convert LLVM
235 bytecode to C, which is enabled with the <tt>-c</tt> option.<p>
236
237 <dt><tt><b>lli</b></tt><dd> <tt>lli</tt> is the LLVM interpreter, which
238 can directly execute LLVM bytecode (although very slowly...). In addition
239 to a simple intepreter, <tt>lli</tt> is also has debugger and tracing
240 modes (entered by specifying <tt>-debug</tt> or <tt>-trace</tt> on the
241 command line, respectively).<p>
242
243 <dt><tt><b>llc</b></tt><dd> <tt>llc</tt> is the LLVM backend compiler,
244 which translates LLVM bytecode to a SPARC assembly file.<p>
245
246 <dt><tt><b>llvmgcc</b></tt><dd> <tt>llvmgcc</tt> is a GCC based C frontend
247 that has been retargeted to emit LLVM code as the machine code output. It
248 works just like any other GCC compiler, taking the typical <tt>-c, -S, -E,
249 -o</tt> options that are typically used. The source code for the
250 <tt>llvmgcc</tt> tool is currently not included in the LLVM cvs tree
251 because it is quite large and not very interesting.<p>
252
253 <ol>
254 <dt><tt><b>gccas</b></tt><dd> This took is invoked by the
255 <tt>llvmgcc</tt> frontend as the "assembler" part of the compiler. This
256 tool actually assembles its input, performs a variety of optimizations,
257 and outputs LLVM bytecode. Thus when you invoke <tt>llvmgcc -c x.c -o
258 x.o</tt>, you are causing <tt>gccas</tt> to be run, which writes the
259 <tt>x.o</tt> file (which is an LLVM bytecode file that can be
260 disassembled or manipulated just like any other bytecode file). The
261 command line interface to <tt>gccas</tt> is designed to be as close as
262 possible to the <b>system</b> <tt>as</tt> utility so that the gcc
263 frontend itself did not have to be modified to interface to a "wierd"
264 assembler.<p>
265
266 <dt><tt><b>gccld</b></tt><dd> <tt>gccld</tt> links together several llvm
267 bytecode files into one bytecode file and does some optimization. It is
268 the linker invoked by the gcc frontend when multiple .o files need to be
269 linked together. Like <tt>gccas</tt> the command line interface of
270 <tt>gccld</tt> is designed to match the system linker, to aid
271 interfacing with the GCC frontend.<p>
272 </ol>
273
274 <dt><tt><b>opt</b></tt><dd> <tt>opt</tt> reads llvm bytecode, applies a
275 series of LLVM to LLVM transformations (which are specified on the command
276 line), and then outputs the resultant bytecode. The '<tt>opt --help</tt>'
277 command is a good way to get a list of the program transformations
278 available in LLVM.<p>
279
280
281 <dt><tt><b>analyze</b></tt><dd> <tt>analyze</tt> is used to run a specific
282 analysis on an input LLVM bytecode file and print out the results. It is
283 primarily useful for debugging analyses, or familiarizing yourself with
284 what an analysis does.<p>
285
286 </dl>
287
288 <!--=====================================================================-->
289 <h2><a name="tutorial">An example using the LLVM tool chain</h2>
290 <!--=====================================================================-->
291
292 <ol>
293 <li>First, create a simple C file, name it 'hello.c':
294 <pre>
295 #include &lt;stdio.h&gt;
296 int main() {
297 printf("hello world\n");
298 return 0;
299 }
300 </pre>
301
302 <li>Next, compile the C file into a LLVM bytecode file:<p>
303
304 <tt>% llvmgcc hello.c -o hello</tt><p>
305
306 This will create two result files: <tt>hello</tt> and
307 <tt>hello.bc</tt>. The <tt>hello.bc</tt> is the LLVM bytecode that
308 corresponds the the compiled program and the library facilities that it
309 required. <tt>hello</tt> is a simple shell script that runs the bytecode
310 file with <tt>lli</tt>, making the result directly executable.<p>
311
312 <li>Run the program. To make sure the program ran, execute one of the
313 following commands:<p>
314
315 <tt>% ./hello</tt><p>
316
317 or<p>
318
319 <tt>% lli hello.bc</tt><p>
320
321 <li>Use the <tt>dis</tt> utility to take a look at the LLVM assembly
322 code:<p>
323
324 <tt>% dis < hello.bc | less</tt><p>
325
326 <li>Compile the program to native Sparc assembly using the code
327 generator:<p>
328
329 <tt>% llc hello.bc -o hello.s</tt><p>
330
331 <li>Assemble the native sparc assemble file into a program:<p>
332
333 <tt>% /opt/SUNWspro/bin/cc -xarch=v9 hello.s -o hello.sparc</tt><p>
334
335 <li>Execute the native sparc program:<p>
336
337 <tt>% ./hello.sparc</tt><p>
338
339 </ol>
340
341
342 <!--=====================================================================-->
343 <h2><a name="links">Links</a></h2>
344 <!--=====================================================================-->
345
346 <p>This document is just an <b>introduction</b> to how to use LLVM to do
347 some simple things... there are many more interesting and complicated things
348 that you can do that aren't documented here (but we'll gladly accept a patch
349 if you want to write something up!). For more information about LLVM, check
350 out:</p>
351
352 <ul>
353 <li><a href="http://llvm.cs.uiuc.edu/">LLVM homepage</a></li>
354 <li><a href="http://tank.cs.uiuc.edu/doxygen/">LLVM doxygen tree</a></li>
355 </ul>
356
357 <hr>
358
359 If you have any questions or run into any snags (or you have any
360 additions...), please send an email to <a
361 href="mailto:sabre@nondot.org">Chris Lattner</a> or <a
362 href="mailto:gshi1@uiuc.edu">Guochun Shi</a>. <p>
363
Guochun Shif4688a82002-07-17 23:05:56 +0000[diff] [blame]364 <!-- Created: Mon Jul 1 02:29:02 CDT 2002 -->
365 <!-- hhmts start -->
Chris Lattner44ac6592002-08-09 16:14:56 +0000[diff] [blame^]366Last modified: Fri Aug 9 11:13:34 CDT 2002
Guochun Shif4688a82002-07-17 23:05:56 +0000[diff] [blame]367<!-- hhmts end -->
368 </body>
369</html>