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John Criswell85ed3612003-06-12 19:34:44 +0000[diff] [blame]3 <head>
4 <title>Getting Started with LLVM System</title>
5 </head>
6
7 <body bgcolor=white>
8 <center><h1>Getting Started with the LLVM System<br><font size=3>By: <a
9 href="mailto:gshi1@uiuc.edu">Guochun Shi</a>,
John Criswellcb27f1e2003-07-01 21:55:57 +0000[diff] [blame]10 <a href="mailto:sabre@nondot.org">Chris Lattner</a>,
11 <a href="mailto:criswell@uiuc.edu">John Criswell</a>, and
John Criswell85ed3612003-06-12 19:34:44 +0000[diff] [blame]12 <a href="http://www.cs.uiuc.edu/~vadve">Vikram Adve</a>
13 </font></h1></center>
14
15 <!--=====================================================================-->
16 <h2><a name="Contents">Contents</a></h2>
17 <!--=====================================================================-->
18
19 <ul>
20 <li><a href="#overview">Overview</a>
John Criswellce760f62003-07-03 16:01:38 +0000[diff] [blame]21 <ol>
John Criswell7a73b802003-06-30 21:59:07 +0000[diff] [blame]22 <li><a href="#requirements">Requirements</a>
23 <ol>
24 <li><a href="#hardware">Hardware</a>
25 <li><a href="#software">Software</a>
26 </ol>
John Criswellce760f62003-07-03 16:01:38 +0000[diff] [blame]27 </ol>
28 <li><a href="#starting">Getting started with LLVM</a>
29 <ol>
John Criswell85ed3612003-06-12 19:34:44 +0000[diff] [blame]30 <li><a href="#quickstart">Getting started quickly (a summary)</a>
John Criswell85ed3612003-06-12 19:34:44 +0000[diff] [blame]31 <li><a href="#terminology">Terminology and Notation</tt></a>
John Criswell85ed3612003-06-12 19:34:44 +0000[diff] [blame]32 <li><a href="#environment">Setting up your environment</a>
John Criswellce760f62003-07-03 16:01:38 +0000[diff] [blame]33 <li><a href="#checkout">Checkout LLVM from CVS</a>
34 <li><a href="#config">Local LLVM Configuration</tt></a>
35 <li><a href="#compile">Compiling the LLVM Suite Source Code</a>
36 <li><a href="#build">Building the LLVM C Front End</a>
37 <li><a href="#objfiles">The location for object files</tt></a>
John Criswell85ed3612003-06-12 19:34:44 +0000[diff] [blame]38 </ol>
39 <li><a href="#layout">Program layout</a>
40 <ol>
41 <li><a href="#cvsdir">CVS directories</a>
John Criswell85ed3612003-06-12 19:34:44 +0000[diff] [blame]42 <li><a href="#include"><tt>llvm/include</tt></a>
43 <li><a href="#lib"><tt>llvm/lib</tt></a>
44 <li><a href="#test"><tt>llvm/test</tt></a>
45 <li><a href="#tools"><tt>llvm/tools</tt></a>
46 </ol>
47 <li><a href="#tutorial">An example using the LLVM tool chain</a>
48 <li><a href="#links">Links</a>
49 </ul>
50
51
52 <!--=====================================================================-->
53 <center>
54 <h2><a name="overview"><b>Overview</b></a></h2>
55 </center>
56 <!--=====================================================================-->
57
John Criswellce760f62003-07-03 16:01:38 +0000[diff] [blame]58 Welcome to LLVM! In order to get started, you first need to know some
59 basic information.
60
61 <p>
62 First, LLVM comes in two pieces. The first piece is the LLVM suite. This
63 contains all of the tools, libraries, and header files needed to use the
64 low level virtual machine. It also contains a test suite that can be used
65 to test the LLVM tools and the GCC front end.
66 <p>
67 The second piece is the GCC front end. This component provides a version
68 of GCC that compiles C code into LLVM bytecode. Currently, the C front end
69 is a modified version of GCC 3.4 (we track the GCC 3.4 development).
70 Once compiled into LLVM bytecode, a program can be manipulated with the
71 LLVM tools.
72
73 <!--=====================================================================-->
74 <h3><a name="requirements"><b>Requirements</b></a></h3>
75 <!--=====================================================================-->
76
77 Before you begin to use the LLVM system, review the requirements given
78 below. This may save you some trouble by knowing ahead of time what
79 hardware and software you will need.
80
81 <!--=====================================================================-->
82 <h4><a name="hardware"><b>Hardware</b></a></h4>
83 <!--=====================================================================-->
84 LLVM is known to work on the following platforms:
85 <ul>
86 <li> Linux on x86
87 <ul>
88 <li> Approximately 700 MB of Free Disk Space
89 <ul>
90 <li>Source code: 30 MB
91 <li>Object code: 670 MB
92 </ul>
93 </ul>
94 <li> Solaris on SparcV9 (Ultrasparc)
95 <ul>
96 <li> Approximately 1.03 GB of Free Disk Space
97 <ul>
98 <li>Source code: 30 MB
99 <li>Object code: 1000 MB
100 </ul>
101 </ul>
102 </ul>
103
104 LLVM <i>may</i> compile on other platforms. The LLVM utilities should work
105 on other platforms, so it should be possible to generate and produce LLVM
106 bytecode on unsupported platforms (although bytecode generated on one
107 platform may not work on another platform). However, the code generators
Misha Brukmanc56e5822003-07-03 16:29:36 +0000[diff] [blame^]108 and Just-In-Time (JIT) compilers only generate SparcV9 or x86 machine code.
John Criswellce760f62003-07-03 16:01:38 +0000[diff] [blame]109
110 <!--=====================================================================-->
111 <h4><a name="software"><b>Software</b></a></h4>
112 <!--=====================================================================-->
113 <p>
114 Compiling LLVM requires that you have several different software packages
115 installed:
116
117 <dl compact>
118 <dt> GCC
119 <dd>
120 The GNU Compiler Collection must be installed with C and C++ language
121 support. GCC 3.2.x works, and GCC 3.x is generally supported.
122
123 <p>
124 Note that we currently do not support any other C++ compiler.
125 </p>
126
127 <dt> GNU Make
128 <dd>
129 The LLVM build system relies upon GNU Make extensions. Therefore, you
130 will need GNU Make (sometimes known as gmake) to build LLVM.
131 <p>
132
133 <dt> Flex and Bison
134 <dd>
135 The LLVM source code is built using flex and bison. You will not be
136 able to configure and compile LLVM without them.
137 <p>
138
139 <dt> GNU M4
140 <dd>
141 If you are installing Bison on your machine for the first time, you
142 will need GNU M4 (version 1.4 or higher).
143 </dl>
144
145 <p>
146 There are some additional tools that you may want to have when working with
147 LLVM:
148 </p>
149
150 <ul>
151 <li>GNU Autoconf
152 <li>GNU M4
153 <p>
154 If you want to make changes to the configure scripts, you will need
155 GNU autoconf (2.53 or higher), and consequently, GNU M4 (version 1.4
156 or higher).
157 </p>
158 </ul>
159
160
161 <p>The <a href="starting">next section</a> of this guide is meant to get
John Criswell85ed3612003-06-12 19:34:44 +0000[diff] [blame]162 you up and running with LLVM and to give you some basic information about
163 the LLVM environment. The <a href"#quickstart">first subsection</a> gives
164 a short summary for those who are already familiar with the system and
165 want to get started as quickly as possible.
166
167 <p>The later sections of this guide describe the <a
John Criswellcb27f1e2003-07-01 21:55:57 +0000[diff] [blame]168 href="#layout">general layout</a> of the the LLVM source-tree, a <a
John Criswell85ed3612003-06-12 19:34:44 +0000[diff] [blame]169 href="#tutorial">simple example</a> using the LLVM tool chain, and <a
170 href="#links">links</a> to find more information about LLVM or to get
171 help via e-mail.
172
173 <!--=====================================================================-->
174 <center>
175 <h2><a name="starting"><b>Getting Started</b></a></h2>
176 </center>
177 <!--=====================================================================-->
178
John Criswell7a73b802003-06-30 21:59:07 +0000[diff] [blame]179 <!--=====================================================================-->
John Criswell85ed3612003-06-12 19:34:44 +0000[diff] [blame]180 <h3><a name="quickstart"><b>Getting Started Quickly (A Summary)</b></a></h3>
181 <!--=====================================================================-->
182
183 Here's the short story for getting up and running quickly with LLVM:
Chris Lattner96768ea2003-02-14 04:22:13 +0000[diff] [blame]184 <ol>
John Criswellce760f62003-07-03 16:01:38 +0000[diff] [blame]185 <li>Build the LLVM suite
186 <ol>
187 <li>Find the path to the CVS repository containing LLVM (we'll call this <i>CVSROOTDIR</i>).
188 <li><tt>cd <i>where-you-want-llvm-to-live</i></tt>
189 <li><tt>cvs -d <i>CVSROOTDIR</i> checkout llvm</tt>
190 <li><tt>cd llvm</tt>
191 <li>Run <tt>configure</tt> to configure the Makefiles and header files.
192 Useful options include:
193 <ul>
194 <li><tt>--with-objroot=<i>directory</i></tt>
195 <br>
196 Specify where object files should be placed during the build.
John Criswell7a73b802003-06-30 21:59:07 +0000[diff] [blame]197
John Criswellce760f62003-07-03 16:01:38 +0000[diff] [blame]198 <li><tt>--with-llvmgccdir=<i>directory</i></tt>
199 <br>
200 Specify where the LLVM C frontend is going to be installed.
201 </ul>
202 <li>Set your LLVM_LIB_SEARCH_PATH environment variable.
203 <li><tt>gmake -k |& tee gnumake.out
204 &nbsp;&nbsp;&nbsp;# this is csh or tcsh syntax</tt>
205 </ol>
206 <p>
John Criswell6e0a6672003-07-03 16:03:39 +0000[diff] [blame]207 <li>Build the LLVM C Front End <b>(optional)</b>
John Criswellce760f62003-07-03 16:01:38 +0000[diff] [blame]208 <ol>
209 <li>Create a directory for the object files to live.
210 <li><tt>cd <i>object file directory</i></tt>
211 <li>Run <tt><i>Pathname-to-where-the-source-code-lives</i>/configure --prefix=<i>LLVMGCCDIR</i></tt> to configure GCC.
212 <li><tt>make bootstrap</tt>
213 <li><tt>make install</tt>
214 </ol>
Chris Lattner96768ea2003-02-14 04:22:13 +0000[diff] [blame]215 </ol>
John Criswell85ed3612003-06-12 19:34:44 +0000[diff] [blame]216
217 <p>See <a href="#environment">Setting up your environment</a> on tips to
218 simplify working with the LLVM front-end and compiled tools. See the
219 other sub-sections below for other useful details in working with LLVM,
220 or go straight to <a href="#layout">Program Layout</a> to learn about the
221 layout of the source code tree.
222
223 <!------------------------------------------------------------------------->
224 <h3><a name="terminology">Terminology and Notation</a></h3>
225 <!------------------------------------------------------------------------->
226
227 <p>Throughout this manual, the following names are used to denote paths
228 specific to the local system and working environment. <i>These are not
John Criswell7a73b802003-06-30 21:59:07 +0000[diff] [blame]229 environment variables you need to set but just strings used in the rest
230 of this document below</i>. In any of the examples below, simply replace
John Criswell85ed3612003-06-12 19:34:44 +0000[diff] [blame]231 each of these names with the appropriate pathname on your local system.
Chris Lattner1db872d2002-09-06 16:26:13 +0000[diff] [blame]232 All these paths are absolute:</p>
John Criswellce760f62003-07-03 16:01:38 +0000[diff] [blame]233 <dl compact>
234 <dt>CVSROOTDIR
235 <dd>
236 This is the path for the CVS repository containing the LLVM source
237 code. Ask the person responsible for your local LLVM installation to
238 give you this path.
239 <p>
240
241 <dt>OBJ_ROOT
242 <dd>
243 This is the top level directory for where the LLVM suite object files
244 will be placed during the build.
245 <p>
246
247 <dt>LLVMGCCDIR
248 <dd>
249 This is the pathname to the location where the LLVM C Front End will
250 be installed. Note that the C front end does not need to be installed
251 during the LLVM suite build; you will just need to know where it will
252 go for configuring the build system and running the test suite later.
253 <p>
254
255 <dt>GCCSRC
256 <dd>
257 This is the pathname of the directory where the LLVM C front end source
258 code can be found.
259 <p>
260
261 <dt>GCCOBJ
262 <dd>
263 This is the pathname of the directory where the LLVM C front end object
264 code will be placed during the build. It can be safely removed once
265 the build is complete.
266 </dl>
267
268 <!------------------------------------------------------------------------->
269 <h3><a name="environment">Setting up your environment</a></h3>
270 <!------------------------------------------------------------------------->
271
272 <p>
273 In order to compile and use LLVM, you will need to set some environment
274 variables. There are also some shell aliases which you may find useful.
275 You can set these on the command line, or better yet, set them in your
276 <tt>.cshrc</tt> or <tt>.profile</tt>.
277
278 <dl compact>
279 <dt><tt>LLVM_LIB_SEARCH_PATH</tt>=<tt><i>LLVMGCCDIR</i>/llvm-gcc/bytecode-libs</tt>
280 <dd>
281 This environment variable helps the LLVM C front end find bytecode
282 libraries that it will need for compilation.
283 <p>
284
285 <dt><tt>PATH</tt>=<tt>${PATH}:<i>OBJ_ROOT</i>/llvm/tools/Debug</tt>
286 <dd>
287 Adding this directory to the end of your path will allow the
288 compilation of the C front end to find the LLVM tools. The LLVM tools
289 are needed for the C front end compile.
290 <p>
291
292 <dt><tt>CC</tt>=<i>Pathname to your GCC compiler</i>
293 <dd>
294 The GCC compiler that you want to use must be the first C compiler in
295 your <tt>PATH</tt>. Otherwise, set this variable so that
296 <tt>configure</tt> will use the GCC compiler that you want to use.
297 <p>
298
299 <dt><tt>CXX</tt>=<i>Pathname to your GCC C++ compiler</i>
300 <dd>
301 The GCC compiler that you want to use must be the first C++ compiler in
302 your <tt>PATH</tt>. Otherwise, set this variable so that
303 <tt>configure</tt> will use the GCC compiler that you want to use.
304 <p>
305
306 <dt><tt>CVSROOT</tt>=<i>CVSROOT</i>
307 <dd>
308 This environment variable tells CVS where to find the CVS repository.
309 <p>
310
311 <dt>alias llvmgcc <i>LLVMGCCDIR</i><tt>/bin/llvm-gcc</tt>
312 <dd>
313 This alias allows you to use the LLVM C front end without putting it in
314 your <tt>PATH</tt> or typing in its complete pathname.
315 </dl>
John Criswell85ed3612003-06-12 19:34:44 +0000[diff] [blame]316
317 <!------------------------------------------------------------------------->
318 <h3><a name="checkout">Checkout LLVM from CVS</a></h3>
319 <!------------------------------------------------------------------------->
320
John Criswell85ed3612003-06-12 19:34:44 +0000[diff] [blame]321 <p>To get a fresh copy of the entire source code, all you
322 need to do is check it out from CVS as follows:
323 <ul>
324 <li><tt>cd <i>where-you-want-llvm-to-live</i></tt>
325 <li><tt>cvs -d <i>CVSROOTDIR</i> checkout llvm</tt></p>
326 </ul>
327
328 <p>This will create an '<tt>llvm</tt>' directory in the current
329 directory and fully populate it with the LLVM source code, Makefiles,
330 test directories, and local copies of documentation files.</p>
331
John Criswellce760f62003-07-03 16:01:38 +0000[diff] [blame]332 <p>
333 Note that the C front end is not included in the CVS repository. You
334 should have either downloaded the source, or better yet, downloaded the
335 binary distribution for your platform.
336 </p>
337
John Criswell85ed3612003-06-12 19:34:44 +0000[diff] [blame]338 <!------------------------------------------------------------------------->
John Criswellce760f62003-07-03 16:01:38 +0000[diff] [blame]339 <h3><a name="config">Local LLVM Configuration</a></h3>
John Criswell85ed3612003-06-12 19:34:44 +0000[diff] [blame]340 <!------------------------------------------------------------------------->
341
John Criswellce760f62003-07-03 16:01:38 +0000[diff] [blame]342 <p>Once checked out from the CVS repository, the LLVM suite source code
343 must be configured via the <tt>configure</tt> script. This script sets
344 variables in <tt>llvm/Makefile.config</tt> and
John Criswell7a73b802003-06-30 21:59:07 +0000[diff] [blame]345 <tt>llvm/include/Config/config.h</tt>.
346
347 <p>
348 The following environment variables are used by <tt>configure</tt> to
349 configure Makefile.config:
350 </p>
John Criswell85ed3612003-06-12 19:34:44 +0000[diff] [blame]351
352 <ul>
John Criswellce760f62003-07-03 16:01:38 +0000[diff] [blame]353 <p><li><i>CXX</i> = Pathname of the C++ compiler to use.
354 <p><li><i>CC</i> = Pathname of the C compiler to use.
John Criswell85ed3612003-06-12 19:34:44 +0000[diff] [blame]355 </ul>
356
John Criswell7a73b802003-06-30 21:59:07 +0000[diff] [blame]357 The following options can be used to set or enable LLVM specific options:
358
John Criswellce760f62003-07-03 16:01:38 +0000[diff] [blame]359 <dl compact>
360 <dt><i>--with-objroot=OBJ_ROOT</i>
361 <dd>
John Criswell7a73b802003-06-30 21:59:07 +0000[diff] [blame]362 Path to the directory where
363 object files, libraries, and executables should be placed.
John Criswellce760f62003-07-03 16:01:38 +0000[diff] [blame]364 If this is set to <tt>.</tt>, then the object files will be placed
365 within the source code tree. If left unspecified, the default value is
366 <tt>.</tt>.
John Criswell7a73b802003-06-30 21:59:07 +0000[diff] [blame]367 (See the Section on <a href=#objfiles>
368 The location for LLVM object files</a>
369 for more information.)
John Criswellce760f62003-07-03 16:01:38 +0000[diff] [blame]370 <p>
371 <dt><i>--with-llvmgccdir=LLVMGCCDIR</i>
372 <dd>
373 Path to the location where the LLVM C front end binaries and
374 associated libraries will be installed.
375 <p>
376 <dt><i>--enable-optimized</i>
377 <dd>
John Criswell7a73b802003-06-30 21:59:07 +0000[diff] [blame]378 Enables optimized compilation (debugging symbols are removed and GCC
John Criswellce760f62003-07-03 16:01:38 +0000[diff] [blame]379 optimization flags are enabled). The default is to use an unoptimized
380 build (also known as a debug build).
381 <p>
382 <dt><i>--enable-jit</i>
383 <dd>
John Criswell7a73b802003-06-30 21:59:07 +0000[diff] [blame]384 Compile the Just In Time (JIT) functionality. This is not available
John Criswellce760f62003-07-03 16:01:38 +0000[diff] [blame]385 on all platforms. The default is dependent on platform, so it is best
386 to explicitly enable it if you want it.
387 </dl>
John Criswell7a73b802003-06-30 21:59:07 +0000[diff] [blame]388
389 In addition to running <tt>configure</tt>, you must set the
John Criswell85ed3612003-06-12 19:34:44 +0000[diff] [blame]390 <tt>LLVM_LIB_SEARCH_PATH</tt> environment variable in your startup scripts.
391 This environment variable is used to locate "system" libraries like
392 "<tt>-lc</tt>" and "<tt>-lm</tt>" when linking. This variable should be set
393 to the absolute path for the bytecode-libs subdirectory of the C front-end
John Criswellce760f62003-07-03 16:01:38 +0000[diff] [blame]394 install, or LLVMGCCDIR/llvm-gcc/bytecode-libs. For example, one might
395 set <tt>LLVM_LIB_SEARCH_PATH</tt> to
John Criswell85ed3612003-06-12 19:34:44 +0000[diff] [blame]396 <tt>/home/vadve/lattner/local/x86/llvm-gcc/bytecode-libs</tt> for the X86
397 version of the C front-end on our research machines.<p>
398
399 <!------------------------------------------------------------------------->
John Criswellce760f62003-07-03 16:01:38 +0000[diff] [blame]400 <h3><a name="compile">Compiling the LLVM Suite Source Code</a></h3>
401 <!------------------------------------------------------------------------->
402
403 Once you have configured LLVM, you can build it. There are three types of
404 builds:
405
406 <dl compact>
407 <dt>Debug Builds
408 <dd>
409 These builds are the default. They compile the tools and libraries
410 with debugging information.
411 <p>
412
413 <dt>Release (Optimized) Builds
414 <dd>
415 These builds are enabled with the <tt>--enable-optimized</tt> option to
416 <tt>configure</tt>. They compile the tools and libraries with GCC
417 optimizer flags on and strip debugging information from the libraries
418 and executables it generates.
419 <p>
420
421 <dt>Profile Builds
422 <dd>
423 These builds are for use with profiling. They compile profiling
424 information into the code for use with programs like <tt>gprof</tt>.
425 Profile builds must be started by setting variables on the
426 <tt>make</tt> command line.
427 </dl>
428
429 Once you have LLVM configured, you can build it by entering the top level
430 <tt>llvm</tt> directory and issuing the following command:
431 <p>
432 <tt>make</tt>
433
434 <p>
435 If you have multiple processors in your machine, you may wish to use some
436 of the parallel build options provided by GNU Make. For example, you could
437 use the command:
438 </p>
439
440 <p>
441 <tt>make -j2</tt>
442
443 <p>
444 There are several other targets which are useful when working with the LLVM
445 source code:
446
447 <dl compact>
448 <dt><tt>make clean</tt>
449 <dd>
450 Removes all files generated by the build. This includes object files,
451 generated C/C++ files, libraries, and executables.
452 <p>
453
454 <dt><tt>make distclean</tt>
455 <dd>
456 Removes everything that <tt>make clean</tt> does, but also removes
457 files generated by <tt>configure</tt>. It attempts to return the
458 source tree to the original state in which it was shipped.
459 <p>
460 </dl>
461
462 It is also possible to override default values from <tt>configure</tt> by
463 declaring variables on the command line. The following are some examples:
464
465 <dl compact>
466 <dt><tt>make ENABLE_OPTIMIZED=1</tt>
467 <dd>
468 Perform a Release (Optimized) build.
469 <p>
470
471 <dt><tt>make ENABLE_PROFILING=1</tt>
472 <dd>
473 Perform a Profiling build.
474 <p>
475
476 <dt><tt>make VERBOSE=1</tt>
477 <dd>
478 Print what <tt>make</tt> is doing on standard output.
479 <p>
480 </dl>
481
482 Every directory in the LLVM source tree includes a <tt>Makefile</tt> to
483 build it and any subdirectories that it contains. Entering any directory
484 inside the LLVM source tree and typing <tt>make</tt> should rebuild
485 anything in or below that directory that is out of date.
486
487 <!------------------------------------------------------------------------->
488 <h3><a name="build">Building the LLVM C Front End</a></h3>
489 <!------------------------------------------------------------------------->
490
491 <b>
492 <p>
493 This step is optional if you have the C front end binary distrubtion for
494 your platform.
495 </p>
496 </b>
497
498 Now that you have the LLVM Suite built, you can build the C front end. For
499 those of you that have built GCC before, the process is very similar.
500 <p>
501 Be forewarned, though: the build system for the C front end is not as
502 polished as the rest of the LLVM code, so there will be many warnings and
503 errors that you will need to ignore for now:
504
505 <ol>
506 <li>Ensure that <tt><i>OBJ_ROOT</i>/llvm/tools/Debug</tt> is at the
507 <i>end</i> of your <tt>PATH</tt> environment variable.
508
509 <li><tt>cd <i>GCCOBJ</i></tt>
510
511 <li>Configure the source code:
512 <ul>
513 <li>On Linux/x86, use
514 <ul>
515 <li><tt><i>GCCSRC</i>/configure --prefix=<i>LLVMGCCDIR</i>
516 --enable-languages=c</tt>
517 </ul>
518
519 <li>On Solaris/Sparc, use
520 <ul>
521 <li><tt><i>GCCSRC</i>/configure --prefix=<i>LLVMGCCDIR</i>
522 --enable-languages=c --target=sparcv9-sun-solaris2</tt>
523 </ul>
524 </ul>
525
526 <li><tt>make bootstrap</tt>
527
528 <li>The build will eventually fail. Don't worry; chances are good that
529 everything that needed to build is built.
530
531 <li><tt>make install</tt>
532 </ol>
533
534 At this point, you should have a working copy of the LLVM C front end
535 installed in <i>LLVMGCCDIR</i>.
536
537 <!------------------------------------------------------------------------->
John Criswell85ed3612003-06-12 19:34:44 +0000[diff] [blame]538 <h3><a name="objfiles">The location for LLVM object files</a></h3>
539 <!------------------------------------------------------------------------->
540
John Criswellce760f62003-07-03 16:01:38 +0000[diff] [blame]541 <p>The LLVM build system sends most output files generated during the build
542 into the directory defined by the variable <i>OBJ_ROOT</i> in
543 <tt>llvm/Makefile.config</tt>, which is set by the <i>--with-objroot</i>
544 option in <tt>configure</tt>. This can be either just your normal LLVM
John Criswell85ed3612003-06-12 19:34:44 +0000[diff] [blame]545 source tree or some other directory writable by you. You may wish to put
546 object files on a different filesystem either to keep them from being backed
547 up or to speed up local builds.
548
John Criswellce760f62003-07-03 16:01:38 +0000[diff] [blame]549 <p>
550 If <i>OBJ_ROOT</i> is specified, then the build system will create a
551 directory tree underneath it that resembles the source code's pathname
552 relative to your home directory.
553 </p>
John Criswell85ed3612003-06-12 19:34:44 +0000[diff] [blame]554
John Criswellce760f62003-07-03 16:01:38 +0000[diff] [blame]555 <p>
556 For example, suppose that <i>OBJ_ROOT</i> is set to <tt>/tmp</tt> and the
557 LLVM suite source code is located in <tt>/usr/home/joe/src/llvm</tt>, where
558 <tt>/usr/home/joe</tt> is the home directory of a user named Joe. Then,
559 the object files will be placed in <tt>/tmp/src/llvm</tt>.
560 </p>
John Criswell85ed3612003-06-12 19:34:44 +0000[diff] [blame]561
John Criswellce760f62003-07-03 16:01:38 +0000[diff] [blame]562 <p>
563 The LLVM build will place files underneath <i>OBJ_ROOT</i> in directories
564 named after the build type:
565 </p>
John Criswell85ed3612003-06-12 19:34:44 +0000[diff] [blame]566
John Criswellce760f62003-07-03 16:01:38 +0000[diff] [blame]567 <dl compact>
568 <dt>Debug Builds
569 <dd>
570 <dl compact>
571 <dt>Tools
572 <dd><tt><i>OBJ_ROOT</i>/llvm/tools/Debug</tt>
573 <dt>Libraries
574 <dd><tt><i>OBJ_ROOT</i>/llvm/lib/Debug</tt>
575 </dl>
576 <p>
John Criswell85ed3612003-06-12 19:34:44 +0000[diff] [blame]577
John Criswellce760f62003-07-03 16:01:38 +0000[diff] [blame]578 <dt>Release Builds
579 <dd>
580 <dl compact>
581 <dt>Tools
582 <dd><tt><i>OBJ_ROOT</i>/llvm/tools/Release</tt>
583 <dt>Libraries
584 <dd><tt><i>OBJ_ROOT</i>/llvm/lib/Release</tt>
585 </dl>
586 <p>
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]587
John Criswellce760f62003-07-03 16:01:38 +0000[diff] [blame]588 <dt>Profile Builds
589 <dd>
590 <dl compact>
591 <dt>Tools
592 <dd><tt><i>OBJ_ROOT</i>/llvm/tools/Profile</tt>
593 <dt>Libraries
594 <dd><tt><i>OBJ_ROOT</i>/llvm/lib/Profile</tt>
595 </dl>
596 </dl>
John Criswell85ed3612003-06-12 19:34:44 +0000[diff] [blame]597
598 <!--=====================================================================-->
599 <center>
600 <h2><a name="layout"><b>Program Layout</b></a></h2>
601 </center>
602 <!--=====================================================================-->
603
John Criswellce760f62003-07-03 16:01:38 +0000[diff] [blame]604 <p>One useful source of information about the LLVM source base is the LLVM <a
John Criswell85ed3612003-06-12 19:34:44 +0000[diff] [blame]605 href="http://www.doxygen.org">doxygen</a> documentation, available at <tt><a
606 href="http://llvm.cs.uiuc.edu/doxygen/">http://llvm.cs.uiuc.edu/doxygen/</a></tt>. The
607 following is a brief introduction to code layout:</p>
608
609
610 <!------------------------------------------------------------------------->
611 <h3><a name="cvsdir"><tt>CVS</tt> directories</a></h3>
612 <!------------------------------------------------------------------------->
613
614 Every directory checked out of CVS will contain a <tt>CVS</tt> directory;
615 for the most part these can just be ignored.
616
617
618 <!------------------------------------------------------------------------->
John Criswell85ed3612003-06-12 19:34:44 +0000[diff] [blame]619 <h3><a name="include"><tt>llvm/include</tt></a></h3>
620 <!------------------------------------------------------------------------->
621
622 This directory contains public header files exported from the LLVM
John Criswell7a73b802003-06-30 21:59:07 +0000[diff] [blame]623 library. The three main subdirectories of this directory are:<p>
John Criswell85ed3612003-06-12 19:34:44 +0000[diff] [blame]624
John Criswell8df90e02003-06-11 20:46:40 +0000[diff] [blame]625 <ol>
John Criswell85ed3612003-06-12 19:34:44 +0000[diff] [blame]626 <li><tt>llvm/include/llvm</tt> - This directory contains all of the LLVM
627 specific header files. This directory also has subdirectories for
628 different portions of LLVM: <tt>Analysis</tt>, <tt>CodeGen</tt>,
629 <tt>Reoptimizer</tt>, <tt>Target</tt>, <tt>Transforms</tt>, etc...
630
631 <li><tt>llvm/include/Support</tt> - This directory contains generic
John Criswellce760f62003-07-03 16:01:38 +0000[diff] [blame]632 support libraries that are independent of LLVM, but are used by LLVM.
John Criswell7a73b802003-06-30 21:59:07 +0000[diff] [blame]633 For example, some C++ STL utilities and a Command Line option processing
634 library.
635
636 <li><tt>llvm/include/Config</tt> - This directory contains header files
637 configured by the <tt>configure</tt> script. They wrap "standard" UNIX
638 and C header files. Source code can include these header files which
639 automatically take care of the conditional #includes that the configure
640 script generates.
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]641 </ol>
John Criswell85ed3612003-06-12 19:34:44 +0000[diff] [blame]642
643 <!------------------------------------------------------------------------->
644 <h3><a name="lib"><tt>llvm/lib</tt></a></h3>
645 <!------------------------------------------------------------------------->
646
John Criswell7a73b802003-06-30 21:59:07 +0000[diff] [blame]647 This directory contains most of the source files of the LLVM system. In
648 LLVM almost all
649 code exists in libraries, making it very easy to share code among the
John Criswell85ed3612003-06-12 19:34:44 +0000[diff] [blame]650 different <a href="#tools">tools</a>.<p>
651
652 <dl compact>
653 <dt><tt>llvm/lib/VMCore/</tt><dd> This directory holds the core LLVM
654 source files that implement core classes like Instruction and BasicBlock.
655
656 <dt><tt>llvm/lib/AsmParser/</tt><dd> This directory holds the source code
657 for the LLVM assembly language parser library.
658
659 <dt><tt>llvm/lib/ByteCode/</tt><dd> This directory holds code for reading
660 and write LLVM bytecode.
661
662 <dt><tt>llvm/lib/CWriter/</tt><dd> This directory implements the LLVM to C
663 converter.
664
665 <dt><tt>llvm/lib/Analysis/</tt><dd> This directory contains a variety of
666 different program analyses, such as Dominator Information, Call Graphs,
667 Induction Variables, Interval Identification, Natural Loop Identification,
668 etc...
669
670 <dt><tt>llvm/lib/Transforms/</tt><dd> This directory contains the source
671 code for the LLVM to LLVM program transformations, such as Aggressive Dead
672 Code Elimination, Sparse Conditional Constant Propagation, Inlining, Loop
673 Invarient Code Motion, Dead Global Elimination, Pool Allocation, and many
674 others...
675
676 <dt><tt>llvm/lib/Target/</tt><dd> This directory contains files that
677 describe various target architectures for code generation. For example,
678 the llvm/lib/Target/Sparc directory holds the Sparc machine
679 description.<br>
680
681 <dt><tt>llvm/lib/CodeGen/</tt><dd> This directory contains the major parts
682 of the code generator: Instruction Selector, Instruction Scheduling, and
683 Register Allocation.
684
685 <dt><tt>llvm/lib/Reoptimizer/</tt><dd> This directory holds code related
686 to the runtime reoptimizer framework that is currently under development.
687
688 <dt><tt>llvm/lib/Support/</tt><dd> This directory contains the source code
689 that corresponds to the header files located in
690 <tt>llvm/include/Support/</tt>.
691 </dl>
692
693 <!------------------------------------------------------------------------->
694 <h3><a name="test"><tt>llvm/test</tt></a></h3>
695 <!------------------------------------------------------------------------->
696
697 <p>This directory contains regression tests and source code that is used to
698 test the LLVM infrastructure...</p>
699
700 <!------------------------------------------------------------------------->
701 <h3><a name="tools"><tt>llvm/tools</tt></a></h3>
702 <!------------------------------------------------------------------------->
703
704 <p>The <b>tools</b> directory contains the executables built out of the
705 libraries above, which form the main part of the user interface. You can
706 always get help for a tool by typing <tt>tool_name --help</tt>. The
707 following is a brief introduction to the most important tools.</p>
708
709 <dl compact>
710 <dt><tt><b>as</b></tt><dd>The assembler transforms the human readable
711 LLVM assembly to LLVM bytecode.<p>
712
713 <dt><tt><b>dis</b></tt><dd>The disassembler transforms the LLVM bytecode
714 to human readable LLVM assembly. Additionally it can convert LLVM
715 bytecode to C, which is enabled with the <tt>-c</tt> option.<p>
716
717 <dt><tt><b>lli</b></tt><dd> <tt>lli</tt> is the LLVM interpreter, which
718 can directly execute LLVM bytecode (although very slowly...). In addition
John Criswellce760f62003-07-03 16:01:38 +0000[diff] [blame]719 to a simple interpreter, <tt>lli</tt> is also has debugger and tracing
John Criswell85ed3612003-06-12 19:34:44 +0000[diff] [blame]720 modes (entered by specifying <tt>-debug</tt> or <tt>-trace</tt> on the
Misha Brukmanc56e5822003-07-03 16:29:36 +0000[diff] [blame^]721 command line, respectively). Finally, for architectures that support it
722 (currently only x86 and Sparc), by default, <tt>lli</tt> will function as
723 a Just-In-Time compiler (if the functionality was compiled in), and will
724 execute the code <i>much</i> faster than the interpreter.<p>
John Criswell85ed3612003-06-12 19:34:44 +0000[diff] [blame]725
726 <dt><tt><b>llc</b></tt><dd> <tt>llc</tt> is the LLVM backend compiler,
Misha Brukmanc56e5822003-07-03 16:29:36 +0000[diff] [blame^]727 which translates LLVM bytecode to a SPARC or x86 assembly file.<p>
John Criswell85ed3612003-06-12 19:34:44 +0000[diff] [blame]728
729 <dt><tt><b>llvmgcc</b></tt><dd> <tt>llvmgcc</tt> is a GCC based C frontend
730 that has been retargeted to emit LLVM code as the machine code output. It
731 works just like any other GCC compiler, taking the typical <tt>-c, -S, -E,
732 -o</tt> options that are typically used. The source code for the
733 <tt>llvmgcc</tt> tool is currently not included in the LLVM cvs tree
734 because it is quite large and not very interesting.<p>
735
736 <ol>
737 <dt><tt><b>gccas</b></tt><dd> This tool is invoked by the
738 <tt>llvmgcc</tt> frontend as the "assembler" part of the compiler. This
739 tool actually assembles LLVM assembly to LLVM bytecode,
John Criswell7a73b802003-06-30 21:59:07 +0000[diff] [blame]740 performs a variety of optimizations,
John Criswell85ed3612003-06-12 19:34:44 +0000[diff] [blame]741 and outputs LLVM bytecode. Thus when you invoke <tt>llvmgcc -c x.c -o
742 x.o</tt>, you are causing <tt>gccas</tt> to be run, which writes the
743 <tt>x.o</tt> file (which is an LLVM bytecode file that can be
744 disassembled or manipulated just like any other bytecode file). The
745 command line interface to <tt>gccas</tt> is designed to be as close as
746 possible to the <b>system</b> '<tt>as</tt>' utility so that the gcc
John Criswellce760f62003-07-03 16:01:38 +0000[diff] [blame]747 frontend itself did not have to be modified to interface to a "weird"
John Criswell85ed3612003-06-12 19:34:44 +0000[diff] [blame]748 assembler.<p>
749
750 <dt><tt><b>gccld</b></tt><dd> <tt>gccld</tt> links together several LLVM
751 bytecode files into one bytecode file and does some optimization. It is
752 the linker invoked by the gcc frontend when multiple .o files need to be
753 linked together. Like <tt>gccas</tt> the command line interface of
754 <tt>gccld</tt> is designed to match the system linker, to aid
755 interfacing with the GCC frontend.<p>
756 </ol>
757
758 <dt><tt><b>opt</b></tt><dd> <tt>opt</tt> reads LLVM bytecode, applies a
759 series of LLVM to LLVM transformations (which are specified on the command
760 line), and then outputs the resultant bytecode. The '<tt>opt --help</tt>'
761 command is a good way to get a list of the program transformations
762 available in LLVM.<p>
763
764
765 <dt><tt><b>analyze</b></tt><dd> <tt>analyze</tt> is used to run a specific
766 analysis on an input LLVM bytecode file and print out the results. It is
767 primarily useful for debugging analyses, or familiarizing yourself with
768 what an analysis does.<p>
769
770 </dl>
771
772 <!--=====================================================================-->
773 <h2><a name="tutorial">An example using the LLVM tool chain</h2>
774 <!--=====================================================================-->
775
776 <ol>
777 <li>First, create a simple C file, name it 'hello.c':
778 <pre>
779 #include &lt;stdio.h&gt;
780 int main() {
781 printf("hello world\n");
782 return 0;
783 }
784 </pre>
785
786 <li>Next, compile the C file into a LLVM bytecode file:<p>
787
788 <tt>% llvmgcc hello.c -o hello</tt><p>
789
790 This will create two result files: <tt>hello</tt> and
791 <tt>hello.bc</tt>. The <tt>hello.bc</tt> is the LLVM bytecode that
792 corresponds the the compiled program and the library facilities that it
793 required. <tt>hello</tt> is a simple shell script that runs the bytecode
794 file with <tt>lli</tt>, making the result directly executable.<p>
795
796 <li>Run the program. To make sure the program ran, execute one of the
797 following commands:<p>
John Criswell8df90e02003-06-11 20:46:40 +0000[diff] [blame]798
John Criswell85ed3612003-06-12 19:34:44 +0000[diff] [blame]799 <tt>% ./hello</tt><p>
800
801 or<p>
802
803 <tt>% lli hello.bc</tt><p>
804
805 <li>Use the <tt>dis</tt> utility to take a look at the LLVM assembly
806 code:<p>
807
808 <tt>% dis < hello.bc | less</tt><p>
809
810 <li>Compile the program to native Sparc assembly using the code
Misha Brukmanc56e5822003-07-03 16:29:36 +0000[diff] [blame^]811 generator (assuming you are currently on a Sparc system):<p>
John Criswell85ed3612003-06-12 19:34:44 +0000[diff] [blame]812
813 <tt>% llc hello.bc -o hello.s</tt><p>
814
815 <li>Assemble the native sparc assemble file into a program:<p>
816
817 <tt>% /opt/SUNWspro/bin/cc -xarch=v9 hello.s -o hello.sparc</tt><p>
818
819 <li>Execute the native sparc program:<p>
820
821 <tt>% ./hello.sparc</tt><p>
822
823 </ol>
824
825
826 <!--=====================================================================-->
John Criswellce760f62003-07-03 16:01:38 +0000[diff] [blame]827 <h2><a name="help">Common Problems</a></h2>
828 <!--=====================================================================-->
829
830 Below are common problems and their remedies:
831
832 <dl compact>
833 <dt><b>When I run configure, it finds the wrong C compiler.</b>
834 <dd>
835 The <tt>configure</tt> script attempts to locate first <tt>gcc</tt> and
836 then <tt>cc</tt>, unless it finds compiler paths set in <tt>CC</tt> and
837 <tt>CXX</tt> for the C and C++ compiler, respectively.
838
839 If <tt>configure</tt> finds the wrong compiler, either adjust your
840 <tt>PATH</tt> environment variable or set <tt>CC</tt> and <tt>CXX</tt>
841 explicitly.
842 <p>
843
844 <dt><b>I compile the code, and I get some error about /localhome</b>.
845 <dd>
846 There are several possible causes for this. The first is that you
847 didn't set a pathname properly when using <tt>configure</tt>, and it
848 defaulted to a pathname that we use on our research machines.
849 <p>
850 Another possibility is that we hardcoded a path in our Makefiles. If
851 you see this, please email the LLVM bug mailing list with the name of
852 the offending Makefile and a description of what is wrong with it.
853
854 <dt><b>The <tt>configure</tt> script finds the right C compiler, but it
855 uses the LLVM linker from a previous build. What do I do?</b>
856 <dd>
857 The <tt>configure</tt> script uses the <tt>PATH</tt> to find
858 executables, so if it's grabbing the wrong linker/assembler/etc, there
859 are two ways to fix it:
860 <ol>
861 <li>Adjust your <tt>PATH</tt> environment variable so that the
862 correct program appears first in the <tt>PATH</tt>. This may work,
863 but may not be convenient when you want them <i>first</i> in your
864 path for other work.
865 <p>
866
867 <li>Run <tt>configure</tt> with an alternative <tt>PATH</tt> that
868 is correct. In a Borne compatible shell, the syntax would be:
869 <p>
870 <tt>PATH=<the path without the bad program> ./configure ...</tt>
871 <p>
872 This is still somewhat inconvenient, but it allows
873 <tt>configure</tt> to do its work without having to adjust your
874 <tt>PATH</tt> permanently.
875 </ol>
876 </dl>
877
878 <!--=====================================================================-->
John Criswell85ed3612003-06-12 19:34:44 +0000[diff] [blame]879 <h2><a name="links">Links</a></h2>
880 <!--=====================================================================-->
881
882 <p>This document is just an <b>introduction</b> to how to use LLVM to do
883 some simple things... there are many more interesting and complicated things
884 that you can do that aren't documented here (but we'll gladly accept a patch
885 if you want to write something up!). For more information about LLVM, check
886 out:</p>
887
888 <ul>
889 <li><a href="http://llvm.cs.uiuc.edu/">LLVM homepage</a></li>
890 <li><a href="http://llvm.cs.uiuc.edu/doxygen/">LLVM doxygen tree</a></li>
John Criswellce760f62003-07-03 16:01:38 +0000[diff] [blame]891 <li><a href="http://llvm.cs.uiuc.edu/docs/Projects.html">Starting a Project that Uses LLVM</a></li>
John Criswell85ed3612003-06-12 19:34:44 +0000[diff] [blame]892 </ul>
893
894 <hr>
895
896 If you have any questions or run into any snags (or you have any
897 additions...), please send an email to
898 <a href="mailto:sabre@nondot.org">Chris Lattner</a>.</p>
899
900 <!-- Created: Mon Jul 1 02:29:02 CDT 2002 -->
901 <!-- hhmts start -->
902Last modified: Tue Jun 3 22:06:43 CDT 2003
903<!-- hhmts end -->
904 </body>
Guochun Shif4688a82002-07-17 23:05:56 +0000[diff] [blame]905</html>