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10 <div class="doc_title">
11 Getting Started with the LLVM System
15 <li><a href="#overview">Overview</a>
16 <li><a href="#quickstart">Getting Started Quickly (A Summary)</a>
17 <li><a href="#requirements">Requirements</a>
19 <li><a href="#hardware">Hardware</a>
20 <li><a href="#software">Software</a>
21 <li><a href="#brokengcc">Broken versions of GCC</a>
24 <li><a href="#starting">Getting Started with LLVM</a>
26 <li><a href="#terminology">Terminology and Notation</a>
27 <li><a href="#environment">Setting Up Your Environment</a>
28 <li><a href="#unpack">Unpacking the LLVM Archives</a>
29 <li><a href="#checkout">Checkout LLVM from CVS</a>
30 <li><a href="#installcf">Install the GCC Front End</a>
31 <li><a href="#config">Local LLVM Configuration</a>
32 <li><a href="#compile">Compiling the LLVM Suite Source Code</a>
33 <li><a href="#objfiles">The Location of LLVM Object Files</a>
34 <li><a href="#optionalconfig">Optional Configuration Items</a>
37 <li><a href="#layout">Program layout</a>
39 <li><a href="#cvsdir"><tt>CVS</tt> directories</a>
40 <li><a href="#include"><tt>llvm/include</tt></a>
41 <li><a href="#lib"><tt>llvm/lib</tt></a>
42 <li><a href="#runtime"><tt>llvm/runtime</tt></a>
43 <li><a href="#test"><tt>llvm/test</tt></a>
44 <li><a href="#llvmtest"><tt>llvm-test</tt></a>
45 <li><a href="#tools"><tt>llvm/tools</tt></a>
46 <li><a href="#utils"><tt>llvm/utils</tt></a>
49 <li><a href="#tutorial">An Example Using the LLVM Tool Chain</a>
50 <li><a href="#problems">Common Problems</a>
51 <li><a href="#links">Links</a>
54 <div class="doc_author">
56 <a href="mailto:criswell@uiuc.edu">John Criswell</a>,
57 <a href="mailto:sabre@nondot.org">Chris Lattner</a>,
58 <a href="http://misha.brukman.net">Misha Brukman</a>,
59 <a href="http://www.cs.uiuc.edu/~vadve">Vikram Adve</a>, and
60 <a href="mailto:gshi1@uiuc.edu">Guochun Shi</a>.
65 <!-- *********************************************************************** -->
66 <div class="doc_section">
67 <a name="overview"><b>Overview</b></a>
69 <!-- *********************************************************************** -->
71 <div class="doc_text">
73 <p>Welcome to LLVM! In order to get started, you first need to know some
74 basic information.</p>
76 <p>First, LLVM comes in two pieces. The first piece is the LLVM suite. This
77 contains all of the tools, libraries, and header files needed to use the low
78 level virtual machine. It contains an assembler, disassembler, bytecode
79 analyzer, and bytecode optimizer. It also contains a test suite that can be
80 used to test the LLVM tools and the GCC front end.</p>
82 <p>The second piece is the GCC front end. This component provides a version of
83 GCC that compiles C and C++ code into LLVM bytecode. Currently, the GCC front
84 end is a modified version of GCC 3.4 (we track the GCC 3.4 development). Once
85 compiled into LLVM bytecode, a program can be manipulated with the LLVM tools
86 from the LLVM suite.</p>
90 <!-- *********************************************************************** -->
91 <div class="doc_section">
92 <a name="quickstart"><b>Getting Started Quickly (A Summary)</b></a>
94 <!-- *********************************************************************** -->
96 <div class="doc_text">
98 <p>Here's the short story for getting up and running quickly with LLVM:</p>
101 <li>Install the GCC front end:
103 <li><tt>cd <i>where-you-want-the-C-front-end-to-live</i></tt>
104 <li><tt>gunzip --stdout cfrontend.<i>platform</i>.tar.gz | tar -xvf -</tt>
105 <li><b>Sparc and MacOS X Only:</b><br>
106 <tt>cd cfrontend/<i>platform</i><br>
110 <li>Get the Source Code
112 <li>With the distributed files:
114 <li><tt>cd <i>where-you-want-llvm-to-live</i></tt>
115 <li><tt>gunzip --stdout llvm-<i>version</i>.tar.gz | tar -xvf -</tt>
119 <li>With anonymous CVS access (or use a <a href="#mirror">mirror</a>):
121 <li><tt>cd <i>where-you-want-llvm-to-live</i></tt></li>
123 :pserver:anon@llvm-cvs.cs.uiuc.edu:/var/cvs/llvm login</tt></li>
124 <li>Hit the return key when prompted for the password.
125 <li><tt>cvs -z3 -d :pserver:anon@llvm-cvs.cs.uiuc.edu:/var/cvs/llvm
127 <li><tt>cd llvm</tt></li>
131 <li>Configure the LLVM Build Environment
133 <li>Change directory to where you want to store the LLVM object
134 files and run <tt>configure</tt> to configure the Makefiles and
135 header files for the default platform. Useful options include:
137 <li><tt>--with-llvmgccdir=<i>directory</i></tt>
138 <p>Specify the full pathname of where the LLVM GCC frontend is
140 <li><tt>--enable-spec2000=<i>directory</i></tt>
141 <p>Enable the SPEC2000 benchmarks for testing. The SPEC2000
142 benchmarks should be available in
143 <tt><i>directory</i></tt>.</p></li>
147 <li>Build the LLVM Suite:
149 <li>Set your LLVM_LIB_SEARCH_PATH environment variable.</li>
150 <li><tt>gmake -k |& tee gnumake.out
151 # this is csh or tcsh syntax</tt></li>
152 <li>If you get an "internal compiler error (ICE)" see <a href="#brokengcc">below</a>.</li>
157 <p>Consult the <a href="#starting">Getting Started with LLVM</a> section for
158 detailed information on configuring and compiling LLVM. See <a
159 href="#environment">Setting Up Your Environment</a> for tips that simplify
160 working with the GCC front end and LLVM tools. Go to <a href="#layout">Program
161 Layout</a> to learn about the layout of the source code tree.</p>
165 <!-- *********************************************************************** -->
166 <div class="doc_section">
167 <a name="requirements"><b>Requirements</b></a>
169 <!-- *********************************************************************** -->
171 <div class="doc_text">
173 <p>Before you begin to use the LLVM system, review the requirements given below.
174 This may save you some trouble by knowing ahead of time what hardware and
175 software you will need.</p>
179 <!-- ======================================================================= -->
180 <div class="doc_subsection">
181 <a name="hardware"><b>Hardware</b></a>
184 <div class="doc_text">
186 <p>LLVM is known to work on the following platforms:</p>
190 <li>Linux on x86 (Pentium and above)
192 <li>Approximately 2.6 GB of Free Disk Space
194 <li>Source code: 57 MB</li>
195 <li>Object code: 2.5 GB</li>
196 <li>GCC front end: 30 MB</li>
201 <li>Solaris on SparcV9 (Ultrasparc)
203 <li>Approximately 2.6 GB of Free Disk Space
205 <li>Source code: 57 MB</li>
206 <li>Object code: 2.5 GB</li>
207 <li>GCC front end: 46 MB</li>
212 <li>FreeBSD on x86 (Pentium and above)
214 <li>Approximately 1 GB of Free Disk Space
216 <li>Source code: 57 MB</li>
217 <li>Object code: 850 MB</li>
218 <li>GCC front end: 40 MB</li>
223 <li>MacOS X on PowerPC
225 <li>Experimental support for static native code generation
226 <li>Approximately 1.6 GB of Free Disk Space
228 <li>Source code: 57 MB</li>
229 <li>Object code: 1.5 GB</li>
230 <li>GCC front end: 36 MB</li>
237 <li><div class="doc_warning">No native code generation</div>
238 <li>Approximately 2 GB of Free Disk Space
240 <li>Source code: 92 MB</li>
241 <li>Object code: 2.8 GB</li>
242 <li>GCC front end: 123 MB</li>
249 <p>The LLVM suite <i>may</i> compile on other platforms, but it is not
250 guaranteed to do so. If compilation is successful, the LLVM utilities should be
251 able to assemble, disassemble, analyze, and optimize LLVM bytecode. Code
252 generation should work as well, although the generated native code may not work
253 on your platform.</p>
255 <p>The GCC front end is not very portable at the moment. If you want to get it
256 to work on another platform, you can download a copy of the source and <a
257 href="CFEBuildInstrs.html">try to compile it</a> on your platform.</p>
261 <!-- ======================================================================= -->
262 <div class="doc_subsection">
263 <a name="software"><b>Software</b></a>
266 <div class="doc_text">
268 <p>Compiling LLVM requires that you have several software packages
272 <li><a href="http://gcc.gnu.org">GCC 3.x with C and C++ language
273 support</a> (See <a href="#brokengcc">below</a> for specific version info)</li>
275 <li><a href="http://savannah.gnu.org/projects/make">GNU Make</a></li>
277 <li><a href="http://www.gnu.org/software/flex">Flex</a></li>
279 <li><a href="http://www.gnu.org/software/bison/bison.html">Bison</a></li>
282 <p>There are some additional tools that you may want to have when working with
286 <li><A href="http://www.gnu.org/software/automake">GNU Automake</A></li>
287 <li><A href="http://www.gnu.org/software/autoconf">GNU Autoconf</A></li>
288 <li><A href="http://savannah.gnu.org/projects/m4">GNU M4</A>
290 <p>If you want to make changes to the configure scripts, you will need GNU
291 autoconf (2.57 or higher), and consequently, GNU M4 (version 1.4 or
292 higher). You will also need automake. Any old version of
293 automake from 1.4p5 on should work; we only use aclocal from that
296 <li><A href="http://www.codesourcery.com/qm/qmtest">QMTest 2.0.3</A></li>
297 <li><A href="http://www.python.org">Python</A>
300 These are needed to use the LLVM test suite. Please note that newer
301 versions of QMTest may not work with the LLVM test suite. QMTest 2.0.3
302 can be retrieved from the QMTest CVS repository using the following
305 <li><tt>cvs -d :pserver:anoncvs@cvs.codesourcery.com:/home/qm/Repository login</tt>
307 <li>When prompted, use <tt>anoncvs</tt> as the password.
309 <li><tt>cvs -d :pserver:anoncvs@cvs.codesourcery.com:/home/qm/Repository co -r release-2-0-3 qm</tt>
317 <!-- ======================================================================= -->
318 <div class="doc_subsection">
319 <a name="brokengcc">Broken versions of GCC</a>
322 <div class="doc_text">
324 <p>LLVM is very demanding of the host C++ compiler, and as such tends to expose
325 bugs in the compiler. In particular, several versions of GCC crash when trying
326 to compile LLVM. We routinely use GCC 3.3.3 and GCC 3.4.0 and have had success
327 with them. Other versions of GCC will probably work as well. GCC versions listed
328 here are known to not work. If you are using one of these versions, please try
329 to upgrade your GCC to something more recent. If you run into a problem with a
330 version of GCC not listed here, please <a href="mailto:llvmdev@cs.uiuc.edu">let
331 us know</a>. Please use the "<tt>gcc -v</tt>" command to find out which version
332 of GCC you are using.
335 <p><b>GCC versions prior to 3.0</b>: GCC 2.96.x and before had several
336 problems in the STL that effectively prevent it from compiling LLVM.
339 <p><b>GCC 3.3.2</b>: This version of GCC suffered from a <a
340 href="http://gcc.gnu.org/PR13392">serious bug</a> which causes it to crash in
341 the "<tt>convert_from_eh_region_ranges_1</tt>" GCC function.</p>
347 <!-- *********************************************************************** -->
348 <div class="doc_section">
349 <a name="starting"><b>Getting Started with LLVM</b></a>
351 <!-- *********************************************************************** -->
353 <div class="doc_text">
355 <p>The remainder of this guide is meant to get you up and running with
356 LLVM and to give you some basic information about the LLVM environment.</p>
358 <p>The later sections of this guide describe the <a
359 href="#layout">general layout</a> of the the LLVM source tree, a <a
360 href="#tutorial">simple example</a> using the LLVM tool chain, and <a
361 href="#links">links</a> to find more information about LLVM or to get
365 <!-- ======================================================================= -->
366 <div class="doc_subsection">
367 <a name="terminology">Terminology and Notation</a>
370 <div class="doc_text">
372 <p>Throughout this manual, the following names are used to denote paths
373 specific to the local system and working environment. <i>These are not
374 environment variables you need to set but just strings used in the rest
375 of this document below</i>. In any of the examples below, simply replace
376 each of these names with the appropriate pathname on your local system.
377 All these paths are absolute:</p>
382 This is the top level directory of the LLVM source tree.
387 This is the top level directory of the LLVM object tree (i.e. the
388 tree where object files and compiled programs will be placed. It
389 can be the same as SRC_ROOT).
394 This is the where the LLVM GCC Front End is installed.
396 For the pre-built GCC front end binaries, the LLVMGCCDIR is
397 <tt>cfrontend/<i>platform</i>/llvm-gcc</tt>.
402 <!-- ======================================================================= -->
403 <div class="doc_subsection">
404 <a name="environment">Setting Up Your Environment</a>
407 <div class="doc_text">
410 In order to compile and use LLVM, you will need to set some environment
411 variables. There are also some shell aliases which you may find useful.
412 You can set these on the command line, or better yet, set them in your
413 <tt>.cshrc</tt> or <tt>.profile</tt>.
416 <dt><tt>LLVM_LIB_SEARCH_PATH</tt>=<tt><i>LLVMGCCDIR</i>/bytecode-libs</tt>
418 This environment variable helps the LLVM GCC front end find bytecode
419 libraries that it will need for compilation.
422 <dt>alias llvmgcc <i>LLVMGCCDIR</i><tt>/bin/gcc</tt>
423 <dt>alias llvmg++ <i>LLVMGCCDIR</i><tt>/bin/g++</tt>
425 This alias allows you to use the LLVM C and C++ front ends without putting
426 them in your <tt>PATH</tt> or typing in their complete pathnames.
431 <!-- ======================================================================= -->
432 <div class="doc_subsection">
433 <a name="unpack">Unpacking the LLVM Archives</a>
436 <div class="doc_text">
439 If you have the LLVM distribution, you will need to unpack it before you
440 can begin to compile it. LLVM is distributed as a set of two files: the LLVM
441 suite and the LLVM GCC front end compiled for your platform. Each
442 file is a TAR archive that is compressed with the gzip program.
445 <p> The files are as follows:
448 <dd>This is the source code to the LLVM suite.
451 <dt>cfrontend-1.3.sparc-sun-solaris2.8.tar.gz
452 <dd>This is the binary release of the GCC front end for Solaris/Sparc.
455 <dt>cfrontend-1.3.i686-redhat-linux-gnu.tar.gz
456 <dd>This is the binary release of the GCC front end for Linux/x86.
459 <dt>cfrontend-1.3.i386-unknown-freebsd5.1.tar.gz
460 <dd>This is the binary release of the GCC front end for FreeBSD/x86.
463 <dt>cfrontend-1.3.powerpc-apple-darwin7.0.0.tar.gz
464 <dd>This is the binary release of the GCC front end for MacOS X/PPC.
469 <!-- ======================================================================= -->
470 <div class="doc_subsection">
471 <a name="checkout">Checkout LLVM from CVS</a>
474 <div class="doc_text">
476 <p>If you have access to our CVS repository, you can get a fresh copy of
477 the entire source code. All you need to do is check it out from CVS as
481 <li><tt>cd <i>where-you-want-llvm-to-live</i></tt>
482 <li><tt>cvs -d :pserver:anon@llvm-cvs.cs.uiuc.edu:/var/cvs/llvm login</tt>
483 <li>Hit the return key when prompted for the password.
484 <li><tt>cvs -z3 -d :pserver:anon@llvm-cvs.cs.uiuc.edu:/var/cvs/llvm co
488 <p>This will create an '<tt>llvm</tt>' directory in the current
489 directory and fully populate it with the LLVM source code, Makefiles,
490 test directories, and local copies of documentation files.</p>
492 <p>If you want to get a specific release (as opposed to the most recent
493 revision), you can specify a label. The following releases have the following
497 <li>Release 1.3: <b>RELEASE_13</b></li>
498 <li>Release 1.2: <b>RELEASE_12</b></li>
499 <li>Release 1.1: <b>RELEASE_11</b></li>
500 <li>Release 1.0: <b>RELEASE_1</b></li>
503 <p>If you would like to get the GCC front end source code, you can also get it
504 from the CVS repository:</p>
507 cvs -z3 -d :pserver:anon@llvm-cvs.cs.uiuc.edu:/var/cvs/llvm co llvm-gcc
510 <p>Please note that you must follow <a href="CFEBuildInstrs.html">these
511 instructions</a> to successfully build the LLVM C front-end.</p>
515 <!-- ======================================================================= -->
516 <div class="doc_subsubsection">
517 <a name="mirrors">LLVM CVS Mirrors</a>
520 <div class="doc_text">
522 <p>If the main CVS server is overloaded or inaccessible, you can try one of
523 these user-hosted mirrors:</p>
526 <li><a href="http://llvm.x10sys.com/">Mirror hosted by eXtensible Systems
531 <!-- ======================================================================= -->
532 <div class="doc_subsection">
533 <a name="installcf">Install the GCC Front End</a>
536 <div class="doc_text">
538 <p>Before configuring and compiling the LLVM suite, you need to extract the LLVM
539 GCC front end from the binary distribution. It is used for building the
540 bytecode libraries later used by the GCC front end for linking programs, and its
541 location must be specified when the LLVM suite is configured.</p>
543 <p>To install the GCC front end, do the following:</p>
546 <li><tt>cd <i>where-you-want-the-front-end-to-live</i></tt></li>
547 <li><tt>gunzip --stdout cfrontend-<i>version</i>.<i>platform</i>.tar.gz | tar -xvf
551 <p>If you are using Solaris/Sparc or MacOS X/PPC, you will need to fix the
554 <p><tt>cd cfrontend/<i>platform</i><br>
555 ./fixheaders</tt></p>
557 <p>The binary versions of the GCC front end may not suit all of your needs. For
558 example, the binary distribution may include an old version of a system header
559 file, not "fix" a header file that needs to be fixed for GCC, or it may be
560 linked with libraries not available on your system.</p>
562 <p>In cases like these, you may want to try <a
563 href="CFEBuildInstrs.html">building the GCC front end from source.</a> This is
564 not for the faint of heart, so be forewarned.</p>
568 <!-- ======================================================================= -->
569 <div class="doc_subsection">
570 <a name="config">Local LLVM Configuration</a>
573 <div class="doc_text">
575 <p>Once checked out from the CVS repository, the LLVM suite source code must be
576 configured via the <tt>configure</tt> script. This script sets variables in
577 <tt>llvm/Makefile.config</tt> and <tt>llvm/include/Config/config.h</tt>. It
578 also populates <i>OBJ_ROOT</i> with the Makefiles needed to begin building
581 <p>The following environment variables are used by the <tt>configure</tt>
582 script to configure the build system:</p>
592 <td>Tells <tt>configure</tt> which C compiler to use. By default,
593 <tt>configure</tt> will look for the first GCC C compiler in
594 <tt>PATH</tt>. Use this variable to override
595 <tt>configure</tt>'s default behavior.</td>
600 <td>Tells <tt>configure</tt> which C++ compiler to use. By default,
601 <tt>configure</tt> will look for the first GCC C++ compiler in
602 <tt>PATH</tt>. Use this variable to override
603 <tt>configure</tt>'s default behavior.</td>
607 <p>The following options can be used to set or enable LLVM specific options:</p>
610 <dt><i>--with-llvmgccdir=LLVMGCCDIR</i>
612 Path to the location where the LLVM GCC front end binaries and
613 associated libraries were installed. This must be specified as an
616 <dt><i>--enable-optimized</i>
618 Enables optimized compilation by default (debugging symbols are removed
619 and GCC optimization flags are enabled). The default is to use an
620 unoptimized build (also known as a debug build).
622 <dt><i>--enable-jit</i>
624 Compile the Just In Time (JIT) compiler functionality. This is not
626 on all platforms. The default is dependent on platform, so it is best
627 to explicitly enable it if you want it.
629 <dt><i>--enable-spec2000</i>
630 <dt><i>--enable-spec2000=<<tt>directory</tt>></i>
632 Enable the use of SPEC2000 when testing LLVM. This is disabled by default
633 (unless <tt>configure</tt> finds SPEC2000 installed). By specifying
634 <tt>directory</tt>, you can tell configure where to find the SPEC2000
635 benchmarks. If <tt>directory</tt> is left unspecified, <tt>configure</tt>
636 uses the default value
637 <tt>/home/vadve/shared/benchmarks/speccpu2000/benchspec</tt>.
639 <dt><i>--enable-spec95</i>
640 <dt><i>--enable-spec95=<<tt>directory</tt>></i>
642 Enable the use of SPEC95 when testing LLVM. It is similar to the
643 <i>--enable-spec2000</i> option.
645 <dt><i>--enable-povray</i>
646 <dt><i>--enable-povray=<<tt>directory</tt>></i>
648 Enable the use of Povray as an external test. Versions of Povray written
649 in C should work. This option is similar to the <i>--enable-spec2000</i>
653 <p>To configure LLVM, follow these steps:</p>
656 <li>Change directory into the object root directory:
658 <tt>cd <i>OBJ_ROOT</i></tt>
661 <li>Run the <tt>configure</tt> script located in the LLVM source tree:
663 <tt><i>SRC_ROOT</i>/configure</tt>
667 <p>In addition to running <tt>configure</tt>, you must set the
668 <tt>LLVM_LIB_SEARCH_PATH</tt> environment variable in your startup scripts.
669 This environment variable is used to locate "system" libraries like
670 "<tt>-lc</tt>" and "<tt>-lm</tt>" when linking. This variable should be set to
671 the absolute path of the <tt>bytecode-libs</tt> subdirectory of the GCC front
672 end, or <i>LLVMGCCDIR</i>/<tt>bytecode-libs</tt>. For example, one might set
673 <tt>LLVM_LIB_SEARCH_PATH</tt> to
674 <tt>/home/vadve/lattner/local/x86/llvm-gcc/bytecode-libs</tt> for the x86
675 version of the GCC front end on our research machines.</p>
679 <!-- ======================================================================= -->
680 <div class="doc_subsection">
681 <a name="compile">Compiling the LLVM Suite Source Code</a>
684 <div class="doc_text">
686 <p>Once you have configured LLVM, you can build it. There are three types of
692 These builds are the default when one types <tt>gmake</tt> (unless the
693 <tt>--enable-optimized</tt> option was used during configuration). The
694 build system will compile the tools and libraries with debugging
698 <dt>Release (Optimized) Builds
700 These builds are enabled with the <tt>--enable-optimized</tt> option to
701 <tt>configure</tt> or by specifying <tt>ENABLE_OPTIMIZED=1</tt> on the
702 <tt>gmake</tt> command line. For these builds, the build system will
703 compile the tools and libraries with GCC optimizations enabled and strip
704 debugging information from the libraries and executables it generates.
709 These builds are for use with profiling. They compile profiling
710 information into the code for use with programs like <tt>gprof</tt>.
711 Profile builds must be started by specifying <tt>ENABLE_PROFILING=1</tt>
712 on the <tt>gmake</tt> command line.
715 <p>Once you have LLVM configured, you can build it by entering the
716 <i>OBJ_ROOT</i> directory and issuing the following command:</p>
718 <p><tt>gmake</tt></p>
720 <p>If the build fails, please <a href="#brokengcc">check here</a> to see if you
721 are using a known broken version of GCC to compile LLVM with.</p>
724 If you have multiple processors in your machine, you may wish to use some of
725 the parallel build options provided by GNU Make. For example, you could use the
728 <p><tt>gmake -j2</tt></p>
730 <p>There are several special targets which are useful when working with the LLVM
734 <dt><tt>gmake clean</tt>
736 Removes all files generated by the build. This includes object files,
737 generated C/C++ files, libraries, and executables.
740 <dt><tt>gmake distclean</tt>
742 Removes everything that <tt>gmake clean</tt> does, but also removes files
743 generated by <tt>configure</tt>. It attempts to return the source tree to the
744 original state in which it was shipped.
747 <dt><tt>gmake install</tt>
749 Installs LLVM libraries and tools in a heirarchy under $PREFIX, specified with
750 <tt>./configure --prefix=[dir]</tt>, defaults to <tt>/usr/local</tt>.
753 <dt><tt>gmake install-bytecode</tt>
755 Assuming you built LLVM into $OBJDIR, when this command is run in
756 $OBJDIR/runtime, it will install bytecode libraries into the GCC front end's
757 bytecode library directory. If you need to update your bytecode libraries,
758 this is the target to use once you've built them.
762 <p>It is also possible to override default values from <tt>configure</tt> by
763 declaring variables on the command line. The following are some examples:</p>
766 <dt><tt>gmake ENABLE_OPTIMIZED=1</tt>
768 Perform a Release (Optimized) build.
771 <dt><tt>gmake ENABLE_PROFILING=1</tt>
773 Perform a Profiling build.
776 <dt><tt>gmake VERBOSE=1</tt>
778 Print what <tt>gmake</tt> is doing on standard output.
782 <p>Every directory in the LLVM object tree includes a <tt>Makefile</tt> to build
783 it and any subdirectories that it contains. Entering any directory inside the
784 LLVM object tree and typing <tt>gmake</tt> should rebuild anything in or below
785 that directory that is out of date.</p>
789 <!-- ======================================================================= -->
790 <div class="doc_subsection">
791 <a name="objfiles">The Location of LLVM Object Files</a>
794 <div class="doc_text">
796 <p>The LLVM build system is capable of sharing a single LLVM source tree among
797 several LLVM builds. Hence, it is possible to build LLVM for several different
798 platforms or configurations using the same source tree.</p>
800 <p>This is accomplished in the typical autoconf manner:</p>
803 <li><p>Change directory to where the LLVM object files should live:</p>
805 <p><tt>cd <i>OBJ_ROOT</i></tt></p></li>
807 <li><p>Run the <tt>configure</tt> script found in the LLVM source
810 <p><tt><i>SRC_ROOT</i>/configure</tt></p></li>
813 <p>The LLVM build will place files underneath <i>OBJ_ROOT</i> in directories
814 named after the build type:</p>
821 <dd><tt><i>OBJ_ROOT</i>/tools/Debug</tt>
823 <dd><tt><i>OBJ_ROOT</i>/lib/Debug</tt>
831 <dd><tt><i>OBJ_ROOT</i>/tools/Release</tt>
833 <dd><tt><i>OBJ_ROOT</i>/lib/Release</tt>
841 <dd><tt><i>OBJ_ROOT</i>/tools/Profile</tt>
843 <dd><tt><i>OBJ_ROOT</i>/lib/Profile</tt>
849 <!-- ======================================================================= -->
850 <div class="doc_subsection">
851 <a name="optionalconfig">Optional Configuration Items</a>
854 <div class="doc_text">
857 If you're running on a linux system that supports the "<a
858 href="http://www.tat.physik.uni-tuebingen.de/~rguenth/linux/binfmt_misc.html">binfmt_misc</a>"
859 module, and you have root access on the system, you can set your system up to
860 execute LLVM bytecode files directly. To do this, use commands like this (the
861 first command may not be required if you are already using the module):</p>
864 $ mount -t binfmt_misc none /proc/sys/fs/binfmt_misc
865 $ echo ':llvm:M::llvm::/path/to/lli:' > /proc/sys/fs/binfmt_misc/register
866 $ chmod u+x hello.bc (if needed)
871 This allows you to execute LLVM bytecode files directly. Thanks to Jack
872 Cummings for pointing this out!
878 <!-- *********************************************************************** -->
879 <div class="doc_section">
880 <a name="layout"><b>Program Layout</b></a>
882 <!-- *********************************************************************** -->
884 <div class="doc_text">
886 <p>One useful source of information about the LLVM source base is the LLVM <a
887 href="http://www.doxygen.org">doxygen</a> documentation available at <tt><a
888 href="http://llvm.cs.uiuc.edu/doxygen/">http://llvm.cs.uiuc.edu/doxygen/</a></tt>.
889 The following is a brief introduction to code layout:</p>
893 <!-- ======================================================================= -->
894 <div class="doc_subsection"><a name="cvsdir"><tt>CVS</tt> directories</a></div>
896 <div class="doc_text">
898 <p>Every directory checked out of CVS will contain a <tt>CVS</tt> directory; for
899 the most part these can just be ignored.</p>
903 <!-- ======================================================================= -->
904 <div class="doc_subsection"><a name="include"><tt>llvm/include</tt></a></div>
906 <div class="doc_text">
908 <p>This directory contains public header files exported from the LLVM
909 library. The three main subdirectories of this directory are:</p>
912 <dt><tt><b>llvm/include/llvm</b></tt></dt>
913 <dd>This directory contains all of the LLVM specific header files. This
914 directory also has subdirectories for different portions of LLVM:
915 <tt>Analysis</tt>, <tt>CodeGen</tt>, <tt>Target</tt>, <tt>Transforms</tt>,
918 <dt><tt><b>llvm/include/llvm/Support</b></tt></dt>
919 <dd>This directory contains generic support libraries that are provided with
920 LLVM but not necessarily specific to LLVM. For example, some C++ STL utilities
921 and a Command Line option processing library store their header files here.
924 <dt><tt><b>llvm/include/llvm/Config</b></tt></dt>
925 <dd>This directory contains header files configured by the <tt>configure</tt>
926 script. They wrap "standard" UNIX and C header files. Source code can
927 include these header files which automatically take care of the conditional
928 #includes that the <tt>configure</tt> script generates.</dd>
932 <!-- ======================================================================= -->
933 <div class="doc_subsection"><a name="lib"><tt>llvm/lib</tt></a></div>
935 <div class="doc_text">
937 <p>This directory contains most of the source files of the LLVM system. In LLVM,
938 almost all code exists in libraries, making it very easy to share code among the
939 different <a href="#tools">tools</a>.</p>
942 <dt><tt><b>llvm/lib/VMCore/</b></tt></dt>
943 <dd> This directory holds the core LLVM source files that implement core
944 classes like Instruction and BasicBlock.</dd>
946 <dt><tt><b>llvm/lib/AsmParser/</b></tt></dt>
947 <dd>This directory holds the source code for the LLVM assembly language parser
950 <dt><tt><b>llvm/lib/ByteCode/</b></tt></dt>
951 <dd>This directory holds code for reading and write LLVM bytecode.</dd>
953 <dt><tt><b>llvm/lib/Analysis/</b></tt><dd>This directory contains a variety of
954 different program analyses, such as Dominator Information, Call Graphs,
955 Induction Variables, Interval Identification, Natural Loop Identification,
958 <dt><tt><b>llvm/lib/Transforms/</b></tt></dt>
959 <dd> This directory contains the source code for the LLVM to LLVM program
960 transformations, such as Aggressive Dead Code Elimination, Sparse Conditional
961 Constant Propagation, Inlining, Loop Invariant Code Motion, Dead Global
962 Elimination, and many others.</dd>
964 <dt><tt><b>llvm/lib/Target/</b></tt></dt>
965 <dd> This directory contains files that describe various target architectures
966 for code generation. For example, the <tt>llvm/lib/Target/SparcV9</tt>
967 directory holds the Sparc machine description while
968 <tt>llvm/lib/Target/CBackend</tt> implements the LLVM-to-C converter</dd>
970 <dt><tt><b>llvm/lib/CodeGen/</b></tt></dt>
971 <dd> This directory contains the major parts of the code generator: Instruction
972 Selector, Instruction Scheduling, and Register Allocation.</dd>
974 <dt><tt><b>llvm/lib/Debugger/</b></tt></dt>
975 <dd> This directory contains the source level debugger library that makes
976 it possible to instrument LLVM programs so that a debugger could identify
977 source code locations at which the program is executing.</dd>
979 <dt><tt><b>llvm/lib/ExecutionEngine/</b></tt></dt>
980 <dd> This directory contains libraries for executing LLVM bytecode directly
981 at runtime in both interpreted and JIT compiled fashions.</dd>
983 <dt><tt><b>llvm/lib/Support/</b></tt></dt>
984 <dd> This directory contains the source code that corresponds to the header
985 files located in <tt>llvm/include/Support/</tt>.</dd>
987 <dt><tt><b>llvm/lib/System/</b></tt></dt>
988 <dd>This directory contains the operating system abstraction layer that
989 shields LLVM from platform-specific coding.</dd>
994 <!-- ======================================================================= -->
995 <div class="doc_subsection"><a name="runtime"><tt>llvm/runtime</tt></a></div>
996 <div class="doc_text">
998 <p>This directory contains libraries which are compiled into LLVM bytecode and
999 used when linking programs with the GCC front end. Most of these libraries are
1000 skeleton versions of real libraries; for example, libc is a stripped down
1001 version of glibc.</p>
1003 <p>Unlike the rest of the LLVM suite, this directory needs the LLVM GCC front
1008 <!-- ======================================================================= -->
1009 <div class="doc_subsection"><a name="test"><tt>llvm/test</tt></a></div>
1010 <div class="doc_text">
1011 <p>This directory contains feature and regression tests and other basic sanity
1012 checks on the LLVM infrastructure. These are intended to run quickly and cover
1013 a lot of territory without being exhaustive.</p>
1016 <!-- ======================================================================= -->
1017 <div class="doc_subsection"><a name="llvmtest"><tt>llvm-test</tt></a></div>
1018 <div class="doc_text">
1019 <p>This is not a directory in the normal llvm module, it is a separate CVS
1020 module that must be checked out (usually to <tt>test/projects</tt>). This
1021 module contains a comprehensive correctness, performance and benchmarking test
1022 suite for LLVM. It is a separate CVS module because not every LLVM user is
1023 interested in downloading or building such a comprehensive test. For further
1024 details on this test suite, please see the
1025 <a href="TestingGuide.html">Testing Guide</a> document.</p>
1028 <!-- ======================================================================= -->
1029 <div class="doc_subsection"><a name="tools"><tt>llvm/tools</tt></a></div>
1030 <div class="doc_text">
1032 <p>The <b>tools</b> directory contains the executables built out of the
1033 libraries above, which form the main part of the user interface. You can
1034 always get help for a tool by typing <tt>tool_name --help</tt>. The
1035 following is a brief introduction to the most important tools:</p>
1038 <dt><tt><b>analyze</b></tt></dt>
1039 <dd><tt>analyze</tt> is used to run a specific
1040 analysis on an input LLVM bytecode file and print out the results. It is
1041 primarily useful for debugging analyses, or familiarizing yourself with
1042 what an analysis does.</dd>
1044 <dt><tt><b>bugpoint</b></tt></dt>
1045 <dd><tt>bugpoint</tt> is used to debug
1046 optimization passes or code generation backends by narrowing down the
1047 given test case to the minimum number of passes and/or instructions that
1048 still cause a problem, whether it is a crash or miscompilation. See <a
1049 href="HowToSubmitABug.html">HowToSubmitABug.html</a> for more information
1050 on using <tt>bugpoint</tt>.</dd>
1052 <dt><tt><b>llvmc</b></tt></dt>
1053 <dd>The LLVM Compiler Driver. This program can
1054 be configured to utilize both LLVM and non-LLVM compilation tools to enable
1055 pre-processing, translation, optimization, assembly, and linking of programs
1056 all from one command line. <tt>llvmc</tt> also takes care of processing the
1057 dependent libraries found in bytecode. This reduces the need to get the
1058 traditional <tt>-l<name></tt> options right on the command line.</dd>
1060 <dt><tt><b>llvm-ar</b></tt></dt>
1061 <dd>The archiver produces an archive containing
1062 the given LLVM bytecode files, optionally with an index for faster
1065 <dt><tt><b>llvm-as</b></tt></dt>
1066 <dd>The assembler transforms the human readable LLVM assembly to LLVM
1069 <dt><tt><b>llvm-dis</b></tt></dt>
1070 <dd>The disassembler transforms the LLVM bytecode to human readable
1073 <dt><tt><b>llvm-link</b></tt></dt>
1074 <dd><tt>llvm-link</tt>, not surprisingly, links multiple LLVM modules into
1075 a single program.</dd>
1077 <dt><tt><b>lli</b></tt></dt>
1078 <dd><tt>lli</tt> is the LLVM interpreter, which
1079 can directly execute LLVM bytecode (although very slowly...). In addition
1080 to a simple interpreter, <tt>lli</tt> also has a tracing mode (entered by
1081 specifying <tt>-trace</tt> on the command line). Finally, for
1082 architectures that support it (currently only x86 and Sparc), by default,
1083 <tt>lli</tt> will function as a Just-In-Time compiler (if the
1084 functionality was compiled in), and will execute the code <i>much</i>
1085 faster than the interpreter.</dd>
1087 <dt><tt><b>llc</b></tt></dt>
1088 <dd> <tt>llc</tt> is the LLVM backend compiler, which
1089 translates LLVM bytecode to a SPARC or x86 assembly file, or to C code (with
1090 the -march=c option).</dd>
1092 <dt><tt><b>llvmgcc</b></tt></dt>
1093 <dd><tt>llvmgcc</tt> is a GCC-based C frontend
1094 that has been retargeted to emit LLVM code as the machine code output. It
1095 works just like any other GCC compiler, taking the typical <tt>-c, -S, -E,
1096 -o</tt> options that are typically used. The source code for the
1097 <tt>llvmgcc</tt> tool is currently not included in the LLVM CVS tree
1098 because it is quite large and not very interesting.
1101 <dt><tt><b>gccas</b></tt></dt>
1102 <dd>This tool is invoked by the <tt>llvmgcc</tt> frontend as the
1103 "assembler" part of the compiler. This tool actually assembles LLVM
1104 assembly to LLVM bytecode, performs a variety of optimizations, and
1105 outputs LLVM bytecode. Thus when you invoke
1106 <tt>llvmgcc -c x.c -o x.o</tt>, you are causing <tt>gccas</tt> to be
1107 run, which writes the <tt>x.o</tt> file (which is an LLVM bytecode file
1108 that can be disassembled or manipulated just like any other bytecode
1109 file). The command line interface to <tt>gccas</tt> is designed to be
1110 as close as possible to the <b>system</b> `<tt>as</tt>' utility so that
1111 the gcc frontend itself did not have to be modified to interface to
1112 a "weird" assembler.</dd>
1114 <dt><tt><b>gccld</b></tt></dt>
1115 <dd><tt>gccld</tt> links together several LLVM bytecode files into one
1116 bytecode file and does some optimization. It is the linker invoked by
1117 the GCC frontend when multiple .o files need to be linked together.
1118 Like <tt>gccas</tt>, the command line interface of <tt>gccld</tt> is
1119 designed to match the system linker, to aid interfacing with the GCC
1125 <dt><tt><b>opt</b></tt></dt>
1126 <dd><tt>opt</tt> reads LLVM bytecode, applies a
1127 series of LLVM to LLVM transformations (which are specified on the command
1128 line), and then outputs the resultant bytecode. The '<tt>opt --help</tt>'
1129 command is a good way to get a list of the program transformations
1130 available in LLVM.</dd>
1134 <!-- ======================================================================= -->
1135 <div class="doc_subsection"><a name="utils"><tt>llvm/utils</tt></a></div>
1136 <div class="doc_text">
1138 <p>This directory contains utilities for working with LLVM source code, and some
1139 of the utilities are actually required as part of the build process because they
1140 are code generators for parts of LLVM infrastructure.</p>
1143 <dt><tt><b>Burg/</b></tt> <dd><tt>Burg</tt> is an instruction selector
1144 generator -- it builds trees on which it then performs pattern-matching to
1145 select instructions according to the patterns the user has specified. Burg
1146 is currently used in the Sparc V9 backend.<p>
1148 <dt><tt><b>codegen-diff</b></tt> <dd><tt>codegen-diff</tt> is a script
1149 that finds differences between code that LLC generates and code that LLI
1150 generates. This is a useful tool if you are debugging one of them,
1151 assuming that the other generates correct output. For the full user
1152 manual, run <tt>`perldoc codegen-diff'</tt>.<p>
1154 <dt><tt><b>cvsupdate</b></tt> <dd><tt>cvsupdate</tt> is a script that will
1155 update your CVS tree, but produce a much cleaner and more organized output
1156 than simply running <tt>`cvs -z3 up -dP'</tt> will. For example, it will group
1157 together all the new and updated files and modified files in separate
1158 sections, so you can see at a glance what has changed. If you are at the
1159 top of your LLVM CVS tree, running <tt>utils/cvsupdate</tt> is the
1160 preferred way of updating the tree.<p>
1162 <dt><tt><b>emacs/</b></tt> <dd>The <tt>emacs</tt> directory contains
1163 syntax-highlighting files which will work with Emacs and XEmacs editors,
1164 providing syntax highlighting support for LLVM assembly files and TableGen
1165 description files. For information on how to use the syntax files, consult
1166 the <tt>README</tt> file in that directory.<p>
1168 <dt><tt><b>getsrcs.sh</b></tt> <dd>The <tt>getsrcs.sh</tt> script finds
1169 and outputs all non-generated source files, which is useful if one wishes
1170 to do a lot of development across directories and does not want to
1171 individually find each file. One way to use it is to run, for example:
1172 <tt>xemacs `utils/getsources.sh`</tt> from the top of your LLVM source
1175 <dt><tt><b>llvmgrep</b></tt></dt>
1176 <dd>This little tool performs an "egrep -H -n" on each source file in LLVM and
1177 passes to it a regular expression provided on <tt>llvmgrep</tt>'s command
1178 line. This is a very efficient way of searching the source base for a
1179 particular regular expression.</dd>
1181 <dt><tt><b>makellvm</b></tt> <dd>The <tt>makellvm</tt> script compiles all
1182 files in the current directory and then compiles and links the tool that
1183 is the first argument. For example, assuming you are in the directory
1184 <tt>llvm/lib/Target/Sparc</tt>, if <tt>makellvm</tt> is in your path,
1185 simply running <tt>makellvm llc</tt> will make a build of the current
1186 directory, switch to directory <tt>llvm/tools/llc</tt> and build it,
1187 causing a re-linking of LLC.<p>
1189 <dt><tt><b>NightlyTest.pl</b></tt> and
1190 <tt><b>NightlyTestTemplate.html</b></tt> <dd>These files are used in a
1191 cron script to generate nightly status reports of the functionality of
1192 tools, and the results can be seen by following the appropriate link on
1193 the <a href="http://llvm.cs.uiuc.edu/">LLVM homepage</a>.<p>
1195 <dt><tt><b>TableGen/</b></tt> <dd>The <tt>TableGen</tt> directory contains
1196 the tool used to generate register descriptions, instruction set
1197 descriptions, and even assemblers from common TableGen description
1200 <dt><tt><b>vim/</b></tt> <dd>The <tt>vim</tt> directory contains
1201 syntax-highlighting files which will work with the VIM editor, providing
1202 syntax highlighting support for LLVM assembly files and TableGen
1203 description files. For information on how to use the syntax files, consult
1204 the <tt>README</tt> file in that directory.<p>
1210 <!-- *********************************************************************** -->
1211 <div class="doc_section">
1212 <a name="tutorial">An Example Using the LLVM Tool Chain</a>
1214 <!-- *********************************************************************** -->
1216 <div class="doc_text">
1219 <li>First, create a simple C file, name it 'hello.c':
1221 #include <stdio.h>
1223 printf("hello world\n");
1228 <li><p>Next, compile the C file into a LLVM bytecode file:</p>
1229 <p><tt>% llvmgcc hello.c -o hello</tt></p>
1231 <p>Note that you should have already built the tools and they have to be
1232 in your path, at least <tt>gccas</tt> and <tt>gccld</tt>.</p>
1234 <p>This will create two result files: <tt>hello</tt> and
1235 <tt>hello.bc</tt>. The <tt>hello.bc</tt> is the LLVM bytecode that
1236 corresponds the the compiled program and the library facilities that it
1237 required. <tt>hello</tt> is a simple shell script that runs the bytecode
1238 file with <tt>lli</tt>, making the result directly executable. Note that
1239 all LLVM optimizations are enabled by default, so there is no need for a
1240 "-O3" switch.</p></li>
1242 <li><p>Run the program. To make sure the program ran, execute one of the
1243 following commands:</p>
1245 <p><tt>% ./hello</tt></p>
1249 <p><tt>% lli hello.bc</tt></p></li>
1251 <li><p>Use the <tt>llvm-dis</tt> utility to take a look at the LLVM assembly
1254 <p><tt>% llvm-dis < hello.bc | less</tt><p></li>
1256 <li><p>Compile the program to native assembly using the LLC code
1259 <p><tt>% llc hello.bc -o hello.s</tt></p>
1261 <li><p>Assemble the native assembly language file into a program:</p>
1263 <p><b>Solaris:</b><tt>% /opt/SUNWspro/bin/cc -xarch=v9 hello.s -o hello.native</tt></p>
1264 <p><b>Others:</b><tt>% gcc hello.s -o hello.native</tt></p>
1266 <li><p>Execute the native code program:</p>
1268 <p><tt>% ./hello.native</tt></p></li>
1274 <!-- *********************************************************************** -->
1275 <div class="doc_section">
1276 <a name="problems">Common Problems</a>
1278 <!-- *********************************************************************** -->
1280 <div class="doc_text">
1282 <p>If you are having problems building or using LLVM, or if you have any other
1283 general questions about LLVM, please consult the <a href="FAQ.html">Frequently
1284 Asked Questions</a> page.</p>
1288 <!-- *********************************************************************** -->
1289 <div class="doc_section">
1290 <a name="links">Links</a>
1292 <!-- *********************************************************************** -->
1294 <div class="doc_text">
1296 <p>This document is just an <b>introduction</b> to how to use LLVM to do
1297 some simple things... there are many more interesting and complicated things
1298 that you can do that aren't documented here (but we'll gladly accept a patch
1299 if you want to write something up!). For more information about LLVM, check
1303 <li><a href="http://llvm.cs.uiuc.edu/">LLVM homepage</a></li>
1304 <li><a href="http://llvm.cs.uiuc.edu/doxygen/">LLVM doxygen tree</a></li>
1305 <li><a href="http://llvm.cs.uiuc.edu/docs/Projects.html">Starting a Project
1306 that Uses LLVM</a></li>
1311 <!-- *********************************************************************** -->
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1320 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
1321 <a href="http://llvm.x10sys.com/rspencer/">Reid Spencer</a><br>
1322 <a href="http://llvm.cs.uiuc.edu">The LLVM Compiler Infrastructure</a><br>
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