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