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In order to get started, you first need to know some +basic information.</p> + +<p>First, LLVM comes in two pieces. The first piece is the LLVM suite. This +contains all of the tools, libraries, and header files needed to use the low +level virtual machine. It contains an assembler, disassembler, bitcode +analyzer and bitcode optimizer. It also contains a test suite that can be +used to test the LLVM tools and the GCC front end.</p> + +<p>The second piece is the GCC front end. This component provides a version of +GCC that compiles C and C++ code into LLVM bitcode. Currently, the GCC front +end uses the GCC parser to convert code to LLVM. Once +compiled into LLVM bitcode, a program can be manipulated with the LLVM tools +from the LLVM suite.</p> + +<p> +There is a third, optional piece called llvm-test. It is a suite of programs +with a testing harness that can be used to further test LLVM's functionality +and performance. +</p> + +</div> + +<!-- *********************************************************************** --> +<div class="doc_section"> + <a name="quickstart"><b>Getting Started Quickly (A Summary)</b></a> +</div> +<!-- *********************************************************************** --> + +<div class="doc_text"> + +<p>Here's the short story for getting up and running quickly with LLVM:</p> + +<ol> + <li>Read the documentation.</li> + <li>Read the documentation.</li> + <li>Remember that you were warned twice about reading the documentation.</li> + <li>Install the llvm-gcc-4.2 front end if you intend to compile C or C++ + (see <a href="#installcf">Install the GCC Front End</a> for details):</li> + <ol> + <li><tt>cd <i>where-you-want-the-C-front-end-to-live</i></tt></li> + <li><tt>gunzip --stdout llvm-gcc-4.2-<i>version</i>-<i>platform</i>.tar.gz | tar -xvf -</tt></li> + <li><tt><i>install-binutils-binary-from-MinGW</i></tt> (Windows only)</li> + <li>Note: If the binary extension is "<tt>.bz</tt>" use <tt>bunzip2</tt> instead of <tt>gunzip</tt>.</li> + <li>Note: On Windows, use <a href="http://www.7-zip.org">7-Zip</a> or a similar archiving tool.</li> + <li>Add <tt>llvm-gcc</tt>'s "<tt>bin</tt>" directory to your <tt>PATH</tt> environment variable.</li> + </ol></li> + + <li>Get the LLVM Source Code + <ul> + <li>With the distributed files (or use <a href="#checkout">SVN</a>): + <ol> + <li><tt>cd <i>where-you-want-llvm-to-live</i></tt> + <li><tt>gunzip --stdout llvm-<i>version</i>.tar.gz | tar -xvf -</tt> + </ol></li> + + </ul></li> + + <li><b>[Optional]</b> Get the Test Suite Source Code + <ul> + <li>With the distributed files (or use <a href="#checkout">SVN</a>): + <ol> + <li><tt>cd <i>where-you-want-llvm-to-live</i></tt> + <li><tt>cd llvm/projects</tt> + <li><tt>gunzip --stdout llvm-test-<i>version</i>.tar.gz | tar -xvf -</tt> + </ol></li> + + </ul></li> + + + <li>Configure the LLVM Build Environment + <ol> + <li><tt>cd <i>where-you-want-to-build-llvm</i></tt></li> + <li><tt><i>/path/to/llvm/</i>configure [options]</tt><br> + Some common options: + + <ul> + <li><tt>--prefix=<i>directory</i></tt> + <p>Specify for <i>directory</i> the full pathname of where you + want the LLVM tools and libraries to be installed (default + <tt>/usr/local</tt>).</p></li> + <li><tt>--with-llvmgccdir=<i>directory</i></tt> + <p>Optionally, specify for <i>directory</i> the full pathname of the + C/C++ front end installation to use with this LLVM configuration. If + not specified, the PATH will be searched. This is only needed if you + want to run the testsuite or do some special kinds of LLVM builds.</p></li> + <li><tt>--enable-spec2000=<i>directory</i></tt> + <p>Enable the SPEC2000 benchmarks for testing. The SPEC2000 + benchmarks should be available in + <tt><i>directory</i></tt>.</p></li> + </ul> + </ol></li> + + <li>Build the LLVM Suite: + <ol> + <li><tt>gmake -k |& tee gnumake.out + # this is csh or tcsh syntax</tt></li> + <li>If you get an "internal compiler error (ICE)" or test failures, see + <a href="#brokengcc">below</a>.</li> + </ol> + +</ol> + +<p>Consult the <a href="#starting">Getting Started with LLVM</a> section for +detailed information on configuring and compiling LLVM. See <a +href="#environment">Setting Up Your Environment</a> for tips that simplify +working with the GCC front end and LLVM tools. Go to <a href="#layout">Program +Layout</a> to learn about the layout of the source code tree.</p> + +</div> + +<!-- *********************************************************************** --> +<div class="doc_section"> + <a name="requirements"><b>Requirements</b></a> +</div> +<!-- *********************************************************************** --> + +<div class="doc_text"> + +<p>Before you begin to use the LLVM system, review the requirements given below. +This may save you some trouble by knowing ahead of time what hardware and +software you will need.</p> + +</div> + +<!-- ======================================================================= --> +<div class="doc_subsection"> + <a name="hardware"><b>Hardware</b></a> +</div> + +<div class="doc_text"> + +<p>LLVM is known to work on the following platforms:</p> + +<table cellpadding="3" summary="Known LLVM platforms"> +<tr> + <th>OS</th> + <th>Arch</th> + <th>Compilers</th> +</tr> +<tr> + <td>AuroraUX</td> + <td>x86<sup><a href="#pf_1">1</a></sup></td> + <td>GCC</td> +</tr> +<tr> + <td>Linux</td> + <td>x86<sup><a href="#pf_1">1</a></sup></td> + <td>GCC</td> +</tr> +<tr> + <td>Linux</td> + <td>amd64</td> + <td>GCC</td> +</tr> +<tr> + <td>Solaris</td> + <td>V9 (Ultrasparc)</td> + <td>GCC</td> +</tr> +<tr> + <td>FreeBSD</td> + <td>x86<sup><a href="#pf_1">1</a></sup></td> + <td>GCC</td> +</tr> +<tr> + <td>MacOS X<sup><a href="#pf_2">2</a></sup></td> + <td>PowerPC</td> + <td>GCC</td> +</tr> +<tr> + <td>MacOS X<sup><a href="#pf_2">2</a>,<a href="#pf_9">9</a></sup></td> + <td>x86</td> + <td>GCC</td> +</tr> +<tr> + <td>Cygwin/Win32</td> + <td>x86<sup><a href="#pf_1">1</a>,<a href="#pf_8">8</a>, + <a href="#pf_11">11</a></sup></td> + <td>GCC 3.4.X, binutils 2.20</td> +</tr> +<tr> + <td>MinGW/Win32</td> + <td>x86<sup><a href="#pf_1">1</a>,<a href="#pf_6">6</a>, + <a href="#pf_8">8</a>, <a href="#pf_10">10</a></sup></td> + <td>GCC 3.4.X, binutils 2.20</td> +</tr> +</table> + +<p>LLVM has partial support for the following platforms:</p> + +<table summary="LLVM partial platform support"> +<tr> + <th>OS</th> + <th>Arch</th> + <th>Compilers</th> +</tr> +<tr> + <td>Windows</td> + <td>x86<sup><a href="#pf_1">1</a></sup></td> + <td>Visual Studio 2005 SP1 or higher<sup><a href="#pf_4">4</a>,<a href="#pf_5">5</a></sup></td> +<tr> + <td>AIX<sup><a href="#pf_3">3</a>,<a href="#pf_4">4</a></sup></td> + <td>PowerPC</td> + <td>GCC</td> +</tr> +<tr> + <td>Linux<sup><a href="#pf_3">3</a>,<a href="#pf_5">5</a></sup></td> + <td>PowerPC</td> + <td>GCC</td> +</tr> + +<tr> + <td>Linux<sup><a href="#pf_7">7</a></sup></td> + <td>Alpha</td> + <td>GCC</td> +</tr> +<tr> + <td>Linux<sup><a href="#pf_7">7</a></sup></td> + <td>Itanium (IA-64)</td> + <td>GCC</td> +</tr> +<tr> + <td>HP-UX<sup><a href="#pf_7">7</a></sup></td> + <td>Itanium (IA-64)</td> + <td>HP aCC</td> +</tr> +</table> + +<p><b>Notes:</b></p> + +<div class="doc_notes"> +<ol> +<li><a name="pf_1">Code generation supported for Pentium processors and +up</a></li> +<li><a name="pf_2">Code generation supported for 32-bit ABI only</a></li> +<li><a name="pf_3">No native code generation</a></li> +<li><a name="pf_4">Build is not complete: one or more tools do not link or function</a></li> +<li><a name="pf_5">The GCC-based C/C++ frontend does not build</a></li> +<li><a name="pf_6">The port is done using the MSYS shell.</a></li> +<li><a name="pf_7">Native code generation exists but is not complete.</a></li> +<li><a name="pf_8">Binutils 2.20 or later is required to build the assembler + generated by LLVM properly.</a></li> +<li><a name="pf_9">XCode 2.5 and gcc 4.0.1</a> (Apple Build 5370) will trip + internal LLVM assert messages when compiled for Release at optimization + levels greater than 0 (i.e., <i>"-O1"</i> and higher). + Add <i>OPTIMIZE_OPTION="-O0"</i> to the build command line + if compiling for LLVM Release or bootstrapping the LLVM toolchain.</li> +<li><a name="pf_10">For MSYS/MinGW on Windows, be sure to install the MSYS + version of the perl package, and be sure it appears in your path + before any Windows-based versions such as Strawberry Perl and + ActivePerl, as these have Windows-specifics that will cause the + build to fail.</a></li> +<li><a name="pf_11">In general, LLVM modules requiring dynamic linking can + not be built on Windows. However, you can build LLVM tools using + <i>"make tools-only"</i>.</li> +</ol> +</div> + +<p>Note that you will need about 1-3 GB of space for a full LLVM build in Debug +mode, depending on the system (it is so large because of all the debugging +information and the fact that the libraries are statically linked into multiple +tools). If you do not need many of the tools and you are space-conscious, you +can pass <tt>ONLY_TOOLS="tools you need"</tt> to make. The Release build +requires considerably less space.</p> + +<p>The LLVM suite <i>may</i> compile on other platforms, but it is not +guaranteed to do so. If compilation is successful, the LLVM utilities should be +able to assemble, disassemble, analyze, and optimize LLVM bitcode. Code +generation should work as well, although the generated native code may not work +on your platform.</p> + +<p>The GCC front end is not very portable at the moment. If you want to get it +to work on another platform, you can download a copy of the source and <a +href="GCCFEBuildInstrs.html">try to compile it</a> on your platform.</p> + +</div> + +<!-- ======================================================================= --> +<div class="doc_subsection"><a name="software"><b>Software</b></a></div> +<div class="doc_text"> + <p>Compiling LLVM requires that you have several software packages + installed. The table below lists those required packages. The Package column + is the usual name for the software package that LLVM depends on. The Version + column provides "known to work" versions of the package. The Notes column + describes how LLVM uses the package and provides other details.</p> + <table summary="Packages required to compile LLVM"> + <tr><th>Package</th><th>Version</th><th>Notes</th></tr> + + <tr> + <td><a href="http://savannah.gnu.org/projects/make">GNU Make</a></td> + <td>3.79, 3.79.1</td> + <td>Makefile/build processor</td> + </tr> + + <tr> + <td><a href="http://gcc.gnu.org">GCC</a></td> + <td>3.4.2</td> + <td>C/C++ compiler<sup><a href="#sf1">1</a></sup></td> + </tr> + + <tr> + <td><a href="http://www.gnu.org/software/texinfo">TeXinfo</a></td> + <td>4.5</td> + <td>For building the CFE</td> + </tr> + + <tr> + <td><a href="http://subversion.tigris.org/project_packages.html">SVN</a></td> + <td>≥1.3</td> + <td>Subversion access to LLVM<sup><a href="#sf2">2</a></sup></td> + </tr> + + <tr> + <td><a href="http://savannah.gnu.org/projects/dejagnu">DejaGnu</a></td> + <td>1.4.2</td> + <td>Automated test suite<sup><a href="#sf3">3</a></sup></td> + </tr> + + <tr> + <td><a href="http://www.tcl.tk/software/tcltk/">tcl</a></td> + <td>8.3, 8.4</td> + <td>Automated test suite<sup><a href="#sf3">3</a></sup></td> + </tr> + + <tr> + <td><a href="http://expect.nist.gov/">expect</a></td> + <td>5.38.0</td> + <td>Automated test suite<sup><a href="#sf3">3</a></sup></td> + </tr> + + <tr> + <td><a href="http://www.perl.com/download.csp">perl</a></td> + <td>≥5.6.0</td> + <td>Nightly tester, utilities</td> + </tr> + + <tr> + <td><a href="http://savannah.gnu.org/projects/m4">GNU M4</a> + <td>1.4</td> + <td>Macro processor for configuration<sup><a href="#sf4">4</a></sup></td> + </tr> + + <tr> + <td><a href="http://www.gnu.org/software/autoconf">GNU Autoconf</a></td> + <td>2.60</td> + <td>Configuration script builder<sup><a href="#sf4">4</a></sup></td> + </tr> + + <tr> + <td><a href="http://www.gnu.org/software/automake">GNU Automake</a></td> + <td>1.9.6</td> + <td>aclocal macro generator<sup><a href="#sf4">4</a></sup></td> + </tr> + + <tr> + <td><a href="http://savannah.gnu.org/projects/libtool">libtool</a></td> + <td>1.5.22</td> + <td>Shared library manager<sup><a href="#sf4">4</a></sup></td> + </tr> + + </table> + + <p><b>Notes:</b></p> + <div class="doc_notes"> + <ol> + <li><a name="sf1">Only the C and C++ languages are needed so there's no + need to build the other languages for LLVM's purposes.</a> See + <a href="#brokengcc">below</a> for specific version info.</li> + <li><a name="sf2">You only need Subversion if you intend to build from the + latest LLVM sources. If you're working from a release distribution, you + don't need Subversion.</a></li> + <li><a name="sf3">Only needed if you want to run the automated test + suite in the <tt>llvm/test</tt> directory.</a></li> + <li><a name="sf4">If you want to make changes to the configure scripts, + you will need GNU autoconf (2.59), and consequently, GNU M4 (version 1.4 + or higher). You will also need automake (1.9.2). We only use aclocal + from that package.</a></li> + </ol> + </div> + + <p>Additionally, your compilation host is expected to have the usual + plethora of Unix utilities. Specifically:</p> + <ul> + <li><b>ar</b> - archive library builder</li> + <li><b>bzip2*</b> - bzip2 command for distribution generation</li> + <li><b>bunzip2*</b> - bunzip2 command for distribution checking</li> + <li><b>chmod</b> - change permissions on a file</li> + <li><b>cat</b> - output concatenation utility</li> + <li><b>cp</b> - copy files</li> + <li><b>date</b> - print the current date/time </li> + <li><b>echo</b> - print to standard output</li> + <li><b>egrep</b> - extended regular expression search utility</li> + <li><b>find</b> - find files/dirs in a file system</li> + <li><b>grep</b> - regular expression search utility</li> + <li><b>gzip*</b> - gzip command for distribution generation</li> + <li><b>gunzip*</b> - gunzip command for distribution checking</li> + <li><b>install</b> - install directories/files </li> + <li><b>mkdir</b> - create a directory</li> + <li><b>mv</b> - move (rename) files</li> + <li><b>ranlib</b> - symbol table builder for archive libraries</li> + <li><b>rm</b> - remove (delete) files and directories</li> + <li><b>sed</b> - stream editor for transforming output</li> + <li><b>sh</b> - Bourne shell for make build scripts</li> + <li><b>tar</b> - tape archive for distribution generation</li> + <li><b>test</b> - test things in file system</li> + <li><b>unzip*</b> - unzip command for distribution checking</li> + <li><b>zip*</b> - zip command for distribution generation</li> + </ul> +</div> + +<!-- ======================================================================= --> +<div class="doc_subsection"> + <a name="brokengcc">Broken versions of GCC and other tools</a> +</div> + +<div class="doc_text"> + +<p>LLVM is very demanding of the host C++ compiler, and as such tends to expose +bugs in the compiler. In particular, several versions of GCC crash when trying +to compile LLVM. We routinely use GCC 3.3.3, 3.4.0, and Apple 4.0.1 +successfully with them (however, see important notes below). Other versions +of GCC will probably work as well. GCC versions listed +here are known to not work. If you are using one of these versions, please try +to upgrade your GCC to something more recent. If you run into a problem with a +version of GCC not listed here, please <a href="mailto:llvmdev@cs.uiuc.edu">let +us know</a>. Please use the "<tt>gcc -v</tt>" command to find out which version +of GCC you are using. +</p> + +<p><b>GCC versions prior to 3.0</b>: GCC 2.96.x and before had several +problems in the STL that effectively prevent it from compiling LLVM. +</p> + +<p><b>GCC 3.2.2 and 3.2.3</b>: These versions of GCC fails to compile LLVM with +a bogus template error. This was fixed in later GCCs.</p> + +<p><b>GCC 3.3.2</b>: This version of GCC suffered from a <a +href="http://gcc.gnu.org/PR13392">serious bug</a> which causes it to crash in +the "<tt>convert_from_eh_region_ranges_1</tt>" GCC function.</p> + +<p><b>Cygwin GCC 3.3.3</b>: The version of GCC 3.3.3 commonly shipped with + Cygwin does not work. Please <a href="GCCFEBuildInstrs.html#cygwin">upgrade + to a newer version</a> if possible.</p> +<p><b>SuSE GCC 3.3.3</b>: The version of GCC 3.3.3 shipped with SuSE 9.1 (and + possibly others) does not compile LLVM correctly (it appears that exception + handling is broken in some cases). Please download the FSF 3.3.3 or upgrade + to a newer version of GCC.</p> +<p><b>GCC 3.4.0 on linux/x86 (32-bit)</b>: GCC miscompiles portions of the + code generator, causing an infinite loop in the llvm-gcc build when built + with optimizations enabled (i.e. a release build).</p> +<p><b>GCC 3.4.2 on linux/x86 (32-bit)</b>: GCC miscompiles portions of the + code generator at -O3, as with 3.4.0. However gcc 3.4.2 (unlike 3.4.0) + correctly compiles LLVM at -O2. A work around is to build release LLVM + builds with "make ENABLE_OPTIMIZED=1 OPTIMIZE_OPTION=-O2 ..."</p> +<p><b>GCC 3.4.x on X86-64/amd64</b>: GCC <a href="http://llvm.org/PR1056"> + miscompiles portions of LLVM</a>.</p> +<p><b>GCC 3.4.4 (CodeSourcery ARM 2005q3-2)</b>: this compiler miscompiles LLVM + when building with optimizations enabled. It appears to work with + "<tt>make ENABLE_OPTIMIZED=1 OPTIMIZE_OPTION=-O1</tt>" or build a debug + build.</p> +<p><b>IA-64 GCC 4.0.0</b>: The IA-64 version of GCC 4.0.0 is known to + miscompile LLVM.</p> +<p><b>Apple Xcode 2.3</b>: GCC crashes when compiling LLVM at -O3 (which is the + default with ENABLE_OPTIMIZED=1. To work around this, build with + "ENABLE_OPTIMIZED=1 OPTIMIZE_OPTION=-O2".</p> +<p><b>GCC 4.1.1</b>: GCC fails to build LLVM with template concept check errors + compiling some files. At the time of this writing, GCC mainline (4.2) + did not share the problem.</p> +<p><b>GCC 4.1.1 on X86-64/amd64</b>: GCC <a href="http://llvm.org/PR1063"> + miscompiles portions of LLVM</a> when compiling llvm itself into 64-bit + code. LLVM will appear to mostly work but will be buggy, e.g. failing + portions of its testsuite.</p> +<p><b>GCC 4.1.2 on OpenSUSE</b>: Seg faults during libstdc++ build and on x86_64 +platforms compiling md5.c gets a mangled constant.</p> +<p><b>GCC 4.1.2 (20061115 (prerelease) (Debian 4.1.1-21)) on Debian</b>: Appears +to miscompile parts of LLVM 2.4. One symptom is ValueSymbolTable complaining +about symbols remaining in the table on destruction.</p> +<p><b>GCC 4.1.2 20071124 (Red Hat 4.1.2-42)</b>: Suffers from the same symptoms +as the previous one. It appears to work with ENABLE_OPTIMIZED=0 (the default).</p> +<p><b>Cygwin GCC 4.3.2 20080827 (beta) 2</b>: + Users <a href="http://llvm.org/PR4145">reported</a> various problems related + with link errors when using this GCC version.</p> +<p><b>Debian GCC 4.3.2 on X86</b>: Crashes building some files in LLVM 2.6.</p> +<p><b>GCC 4.3.3 (Debian 4.3.3-10) on ARM</b>: Miscompiles parts of LLVM 2.6 +when optimizations are turned on. The symptom is an infinite loop in +FoldingSetImpl::RemoveNode while running the code generator.</p> +<p><b>GNU ld 2.16.X</b>. Some 2.16.X versions of the ld linker will produce very +long warning messages complaining that some ".gnu.linkonce.t.*" symbol was +defined in a discarded section. You can safely ignore these messages as they are +erroneous and the linkage is correct. These messages disappear using ld +2.17.</p> + +<p><b>GNU binutils 2.17</b>: Binutils 2.17 contains <a +href="http://sourceware.org/bugzilla/show_bug.cgi?id=3111">a bug</a> which +causes huge link times (minutes instead of seconds) when building LLVM. We +recommend upgrading to a newer version (2.17.50.0.4 or later).</p> + +<p><b>GNU Binutils 2.19.1 Gold</b>: This version of Gold contained +<a href="http://sourceware.org/bugzilla/show_bug.cgi?id=9836">a bug</a> +which causes intermittent failures when building LLVM with position independent +code. The symptom is an error about cyclic dependencies. We recommend +upgrading to a newer version of Gold.</p> + +</div> + + + +<!-- *********************************************************************** --> +<div class="doc_section"> + <a name="starting"><b>Getting Started with LLVM</b></a> +</div> +<!-- *********************************************************************** --> + +<div class="doc_text"> + +<p>The remainder of this guide is meant to get you up and running with +LLVM and to give you some basic information about the LLVM environment.</p> + +<p>The later sections of this guide describe the <a +href="#layout">general layout</a> of the the LLVM source tree, a <a +href="#tutorial">simple example</a> using the LLVM tool chain, and <a +href="#links">links</a> to find more information about LLVM or to get +help via e-mail.</p> +</div> + +<!-- ======================================================================= --> +<div class="doc_subsection"> + <a name="terminology">Terminology and Notation</a> +</div> + +<div class="doc_text"> + +<p>Throughout this manual, the following names are used to denote paths +specific to the local system and working environment. <i>These are not +environment variables you need to set but just strings used in the rest +of this document below</i>. In any of the examples below, simply replace +each of these names with the appropriate pathname on your local system. +All these paths are absolute:</p> + +<dl> + <dt>SRC_ROOT + <dd> + This is the top level directory of the LLVM source tree. + <br><br> + + <dt>OBJ_ROOT + <dd> + This is the top level directory of the LLVM object tree (i.e. the + tree where object files and compiled programs will be placed. It + can be the same as SRC_ROOT). + <br><br> + + <dt>LLVMGCCDIR + <dd> + This is where the LLVM GCC Front End is installed. + <p> + For the pre-built GCC front end binaries, the LLVMGCCDIR is + <tt>llvm-gcc/<i>platform</i>/llvm-gcc</tt>. +</dl> + +</div> + +<!-- ======================================================================= --> +<div class="doc_subsection"> + <a name="environment">Setting Up Your Environment</a> +</div> + +<div class="doc_text"> + +<p> +In order to compile and use LLVM, you may need to set some environment +variables. + +<dl> + <dt><tt>LLVM_LIB_SEARCH_PATH</tt>=<tt>/path/to/your/bitcode/libs</tt></dt> + <dd>[Optional] This environment variable helps LLVM linking tools find the + locations of your bitcode libraries. It is provided only as a + convenience since you can specify the paths using the -L options of the + tools and the C/C++ front-end will automatically use the bitcode files + installed in its + <tt>lib</tt> directory.</dd> +</dl> + +</div> + +<!-- ======================================================================= --> +<div class="doc_subsection"> + <a name="unpack">Unpacking the LLVM Archives</a> +</div> + +<div class="doc_text"> + +<p> +If you have the LLVM distribution, you will need to unpack it before you +can begin to compile it. LLVM is distributed as a set of two files: the LLVM +suite and the LLVM GCC front end compiled for your platform. There is an +additional test suite that is optional. Each file is a TAR archive that is +compressed with the gzip program. +</p> + +<p>The files are as follows, with <em>x.y</em> marking the version number: +<dl> + <dt><tt>llvm-x.y.tar.gz</tt></dt> + <dd>Source release for the LLVM libraries and tools.<br></dd> + + <dt><tt>llvm-test-x.y.tar.gz</tt></dt> + <dd>Source release for the LLVM test suite.</dd> + + <dt><tt>llvm-gcc-4.2-x.y.source.tar.gz</tt></dt> + <dd>Source release of the llvm-gcc-4.2 front end. See README.LLVM in the root + directory for build instructions.<br></dd> + + <dt><tt>llvm-gcc-4.2-x.y-platform.tar.gz</tt></dt> + <dd>Binary release of the llvm-gcc-4.2 front end for a specific platform.<br></dd> + +</dl> + +</div> + +<!-- ======================================================================= --> +<div class="doc_subsection"> + <a name="checkout">Checkout LLVM from Subversion</a> +</div> + +<div class="doc_text"> + +<p>If you have access to our Subversion repository, you can get a fresh copy of +the entire source code. All you need to do is check it out from Subversion as +follows:</p> + +<ul> + <li><tt>cd <i>where-you-want-llvm-to-live</i></tt></li> + <li>Read-Only: <tt>svn co http://llvm.org/svn/llvm-project/llvm/trunk llvm</tt></li> + <li>Read-Write:<tt>svn co https://user@llvm.org/svn/llvm-project/llvm/trunk + llvm</tt></li> +</ul> + + +<p>This will create an '<tt>llvm</tt>' directory in the current +directory and fully populate it with the LLVM source code, Makefiles, +test directories, and local copies of documentation files.</p> + +<p>If you want to get a specific release (as opposed to the most recent +revision), you can checkout it from the '<tt>tags</tt>' directory (instead of +'<tt>trunk</tt>'). The following releases are located in the following +subdirectories of the '<tt>tags</tt>' directory:</p> + +<ul> +<li>Release 2.6: <b>RELEASE_26</b></li> +<li>Release 2.5: <b>RELEASE_25</b></li> +<li>Release 2.4: <b>RELEASE_24</b></li> +<li>Release 2.3: <b>RELEASE_23</b></li> +<li>Release 2.2: <b>RELEASE_22</b></li> +<li>Release 2.1: <b>RELEASE_21</b></li> +<li>Release 2.0: <b>RELEASE_20</b></li> +<li>Release 1.9: <b>RELEASE_19</b></li> +<li>Release 1.8: <b>RELEASE_18</b></li> +<li>Release 1.7: <b>RELEASE_17</b></li> +<li>Release 1.6: <b>RELEASE_16</b></li> +<li>Release 1.5: <b>RELEASE_15</b></li> +<li>Release 1.4: <b>RELEASE_14</b></li> +<li>Release 1.3: <b>RELEASE_13</b></li> +<li>Release 1.2: <b>RELEASE_12</b></li> +<li>Release 1.1: <b>RELEASE_11</b></li> +<li>Release 1.0: <b>RELEASE_1</b></li> +</ul> + +<p>If you would like to get the LLVM test suite (a separate package as of 1.4), +you get it from the Subversion repository:</p> + +<div class="doc_code"> +<pre> +% cd llvm/projects +% svn co http://llvm.org/svn/llvm-project/test-suite/trunk llvm-test +</pre> +</div> + +<p>By placing it in the <tt>llvm/projects</tt>, it will be automatically +configured by the LLVM configure script as well as automatically updated when +you run <tt>svn update</tt>.</p> + +<p>If you would like to get the GCC front end source code, you can also get it +and build it yourself. Please follow <a href="GCCFEBuildInstrs.html">these +instructions</a> to successfully get and build the LLVM GCC front-end.</p> + +</div> + +<!-- ======================================================================= --> +<div class="doc_subsection"> + <a name="installcf">Install the GCC Front End</a> +</div> + +<div class="doc_text"> + +<p>Before configuring and compiling the LLVM suite (or if you want to use just the LLVM +GCC front end) you can optionally extract the front end from the binary distribution. +It is used for running the llvm-test testsuite and for compiling C/C++ programs. Note that +you can optionally <a href="GCCFEBuildInstrs.html">build llvm-gcc yourself</a> after building the +main LLVM repository.</p> + +<p>To install the GCC front end, do the following (on Windows, use an archival tool +like <a href="http://www.7-zip.org">7-zip</a> that understands gzipped tars):</p> + +<ol> + <li><tt>cd <i>where-you-want-the-front-end-to-live</i></tt></li> + <li><tt>gunzip --stdout llvm-gcc-4.2-<i>version</i>-<i>platform</i>.tar.gz | tar -xvf + -</tt></li> +</ol> + +<p>Once the binary is uncompressed, if you're using a *nix-based system, add a symlink for +<tt>llvm-gcc</tt> and <tt>llvm-g++</tt> to some directory in your path. If you're using a +Windows-based system, add the <tt>bin</tt> subdirectory of your front end installation directory +to your <tt>PATH</tt> environment variable. For example, if you uncompressed the binary to +<tt>c:\llvm-gcc</tt>, add <tt>c:\llvm-gcc\bin</tt> to your <tt>PATH</tt>.</p> + +<p>If you now want to build LLVM from source, when you configure LLVM, it will +automatically detect <tt>llvm-gcc</tt>'s presence (if it is in your path) enabling its +use in llvm-test. Note that you can always build or install <tt>llvm-gcc</tt> at any +point after building the main LLVM repository: just reconfigure llvm and +llvm-test will pick it up. +</p> + +<p>As a convenience for Windows users, the front end binaries for MinGW/x86 include +versions of the required w32api and mingw-runtime binaries. The last remaining step for +Windows users is to simply uncompress the binary binutils package from +<a href="http://mingw.org/">MinGW</a> into your front end installation directory. While the +front end installation steps are not quite the same as a typical manual MinGW installation, +they should be similar enough to those who have previously installed MinGW on Windows systems.</p> + +<p>To install binutils on Windows:</p> + +<ol> + <li><tt><i>download GNU Binutils from <a href="http://sourceforge.net/projects/mingw/files/">MinGW Downloads</a></i></tt></li> + <li><tt>cd <i>where-you-uncompressed-the-front-end</i></tt></li> + <li><tt><i>uncompress archived binutils directories (not the tar file) into the current directory</i></tt></li> +</ol> + +<p>The binary versions of the LLVM GCC front end may not suit all of your needs. For +example, the binary distribution may include an old version of a system header +file, not "fix" a header file that needs to be fixed for GCC, or it may be linked with +libraries not available on your system. In cases like these, you may want to try +<a href="GCCFEBuildInstrs.html">building the GCC front end from source</a>. Thankfully, +this is much easier now than it was in the past.</p> + +<p>We also do not currently support updating of the GCC front end by manually overlaying +newer versions of the w32api and mingw-runtime binary packages that may become available +from MinGW. At this time, it's best to think of the MinGW LLVM GCC front end binary as +a self-contained convenience package that requires Windows users to simply download and +uncompress the GNU Binutils binary package from the MinGW project.</p> + +<p>Regardless of your platform, if you discover that installing the LLVM GCC front end +binaries is not as easy as previously described, or you would like to suggest improvements, +please let us know how you would like to see things improved by dropping us a note on our +<a href="http://llvm.org/docs/#maillist">mailing list</a>.</p> + +</div> + +<!-- ======================================================================= --> +<div class="doc_subsection"> + <a name="config">Local LLVM Configuration</a> +</div> + +<div class="doc_text"> + + <p>Once checked out from the Subversion repository, the LLVM suite source + code must be +configured via the <tt>configure</tt> script. This script sets variables in the +various <tt>*.in</tt> files, most notably <tt>llvm/Makefile.config</tt> and +<tt>llvm/include/Config/config.h</tt>. It also populates <i>OBJ_ROOT</i> with +the Makefiles needed to begin building LLVM.</p> + +<p>The following environment variables are used by the <tt>configure</tt> +script to configure the build system:</p> + +<table summary="LLVM configure script environment variables"> + <tr><th>Variable</th><th>Purpose</th></tr> + <tr> + <td>CC</td> + <td>Tells <tt>configure</tt> which C compiler to use. By default, + <tt>configure</tt> will look for the first GCC C compiler in + <tt>PATH</tt>. Use this variable to override + <tt>configure</tt>'s default behavior.</td> + </tr> + <tr> + <td>CXX</td> + <td>Tells <tt>configure</tt> which C++ compiler to use. By default, + <tt>configure</tt> will look for the first GCC C++ compiler in + <tt>PATH</tt>. Use this variable to override + <tt>configure</tt>'s default behavior.</td> + </tr> +</table> + +<p>The following options can be used to set or enable LLVM specific options:</p> + +<dl> + <dt><i>--with-llvmgccdir</i></dt> + <dd>Path to the LLVM C/C++ FrontEnd to be used with this LLVM configuration. + The value of this option should specify the full pathname of the C/C++ Front + End to be used. If this option is not provided, the PATH will be searched for + a program named <i>llvm-gcc</i> and the C/C++ FrontEnd install directory will + be inferred from the path found. If the option is not given, and no llvm-gcc + can be found in the path then a warning will be produced by + <tt>configure</tt> indicating this situation. LLVM may still be built with + the <tt>tools-only</tt> target but attempting to build the runtime libraries + will fail as these libraries require llvm-gcc and llvm-g++. See + <a href="#installcf">Install the GCC Front End</a> for details on installing + the C/C++ Front End. See + <a href="GCCFEBuildInstrs.html">Bootstrapping the LLVM C/C++ Front-End</a> + for details on building the C/C++ Front End.</dd> + <dt><i>--with-tclinclude</i></dt> + <dd>Path to the tcl include directory under which <tt>tclsh</tt> can be + found. Use this if you have multiple tcl installations on your machine and you + want to use a specific one (8.x) for LLVM. LLVM only uses tcl for running the + dejagnu based test suite in <tt>llvm/test</tt>. If you don't specify this + option, the LLVM configure script will search for the tcl 8.4 and 8.3 + releases. + <br><br> + </dd> + <dt><i>--enable-optimized</i></dt> + <dd> + Enables optimized compilation (debugging symbols are removed + and GCC optimization flags are enabled). Note that this is the default + setting if you are using the LLVM distribution. The default behavior + of an Subversion checkout is to use an unoptimized build (also known as a + debug build). + <br><br> + </dd> + <dt><i>--enable-debug-runtime</i></dt> + <dd> + Enables debug symbols in the runtime libraries. The default is to strip + debug symbols from the runtime libraries. + </dd> + <dt><i>--enable-jit</i></dt> + <dd> + Compile the Just In Time (JIT) compiler functionality. This is not + available + on all platforms. The default is dependent on platform, so it is best + to explicitly enable it if you want it. + <br><br> + </dd> + <dt><i>--enable-targets=</i><tt>target-option</tt></dt> + <dd>Controls which targets will be built and linked into llc. The default + value for <tt>target_options</tt> is "all" which builds and links all + available targets. The value "host-only" can be specified to build only a + native compiler (no cross-compiler targets available). The "native" target is + selected as the target of the build host. You can also specify a comma + separated list of target names that you want available in llc. The target + names use all lower case. The current set of targets is: <br> + <tt>alpha, ia64, powerpc, skeleton, sparc, x86</tt>. + <br><br></dd> + <dt><i>--enable-doxygen</i></dt> + <dd>Look for the doxygen program and enable construction of doxygen based + documentation from the source code. This is disabled by default because + generating the documentation can take a long time and producess 100s of + megabytes of output.</dd> + <dt><i>--with-udis86</i></dt> + <dd>LLVM can use external disassembler library for various purposes (now it's + used only for examining code produced by JIT). This option will enable usage + of <a href="http://udis86.sourceforge.net/">udis86</a> x86 (both 32 and 64 + bits) disassembler library.</dd> +</dl> + +<p>To configure LLVM, follow these steps:</p> + +<ol> + <li><p>Change directory into the object root directory:</p> + + <div class="doc_code"><pre>% cd <i>OBJ_ROOT</i></pre></div></li> + + <li><p>Run the <tt>configure</tt> script located in the LLVM source + tree:</p> + + <div class="doc_code"> + <pre>% <i>SRC_ROOT</i>/configure --prefix=/install/path [other options]</pre> + </div></li> +</ol> + +</div> + +<!-- ======================================================================= --> +<div class="doc_subsection"> + <a name="compile">Compiling the LLVM Suite Source Code</a> +</div> + +<div class="doc_text"> + +<p>Once you have configured LLVM, you can build it. There are three types of +builds:</p> + +<dl> + <dt>Debug Builds + <dd> + These builds are the default when one is using an Subversion checkout and + types <tt>gmake</tt> (unless the <tt>--enable-optimized</tt> option was + used during configuration). The build system will compile the tools and + libraries with debugging information. To get a Debug Build using the + LLVM distribution the <tt>--disable-optimized</tt> option must be passed + to <tt>configure</tt>. + <br><br> + + <dt>Release (Optimized) Builds + <dd> + These builds are enabled with the <tt>--enable-optimized</tt> option to + <tt>configure</tt> or by specifying <tt>ENABLE_OPTIMIZED=1</tt> on the + <tt>gmake</tt> command line. For these builds, the build system will + compile the tools and libraries with GCC optimizations enabled and strip + debugging information from the libraries and executables it generates. + Note that Release Builds are default when using an LLVM distribution. + <br><br> + + <dt>Profile Builds + <dd> + These builds are for use with profiling. They compile profiling + information into the code for use with programs like <tt>gprof</tt>. + Profile builds must be started by specifying <tt>ENABLE_PROFILING=1</tt> + on the <tt>gmake</tt> command line. +</dl> + +<p>Once you have LLVM configured, you can build it by entering the +<i>OBJ_ROOT</i> directory and issuing the following command:</p> + +<div class="doc_code"><pre>% gmake</pre></div> + +<p>If the build fails, please <a href="#brokengcc">check here</a> to see if you +are using a version of GCC that is known not to compile LLVM.</p> + +<p> +If you have multiple processors in your machine, you may wish to use some of +the parallel build options provided by GNU Make. For example, you could use the +command:</p> + +<div class="doc_code"><pre>% gmake -j2</pre></div> + +<p>There are several special targets which are useful when working with the LLVM +source code:</p> + +<dl> + <dt><tt>gmake clean</tt> + <dd> + Removes all files generated by the build. This includes object files, + generated C/C++ files, libraries, and executables. + <br><br> + + <dt><tt>gmake dist-clean</tt> + <dd> + Removes everything that <tt>gmake clean</tt> does, but also removes files + generated by <tt>configure</tt>. It attempts to return the source tree to the + original state in which it was shipped. + <br><br> + + <dt><tt>gmake install</tt> + <dd> + Installs LLVM header files, libraries, tools, and documentation in a + hierarchy + under $PREFIX, specified with <tt>./configure --prefix=[dir]</tt>, which + defaults to <tt>/usr/local</tt>. + <br><br> + + <dt><tt>gmake -C runtime install-bytecode</tt> + <dd> + Assuming you built LLVM into $OBJDIR, when this command is run, it will + install bitcode libraries into the GCC front end's bitcode library + directory. If you need to update your bitcode libraries, + this is the target to use once you've built them. + <br><br> +</dl> + +<p>Please see the <a href="MakefileGuide.html">Makefile Guide</a> for further +details on these <tt>make</tt> targets and descriptions of other targets +available.</p> + +<p>It is also possible to override default values from <tt>configure</tt> by +declaring variables on the command line. The following are some examples:</p> + +<dl> + <dt><tt>gmake ENABLE_OPTIMIZED=1</tt> + <dd> + Perform a Release (Optimized) build. + <br><br> + + <dt><tt>gmake ENABLE_OPTIMIZED=1 DISABLE_ASSERTIONS=1</tt> + <dd> + Perform a Release (Optimized) build without assertions enabled. + <br><br> + + <dt><tt>gmake ENABLE_OPTIMIZED=0</tt> + <dd> + Perform a Debug build. + <br><br> + + <dt><tt>gmake ENABLE_PROFILING=1</tt> + <dd> + Perform a Profiling build. + <br><br> + + <dt><tt>gmake VERBOSE=1</tt> + <dd> + Print what <tt>gmake</tt> is doing on standard output. + <br><br> + + <dt><tt>gmake TOOL_VERBOSE=1</tt></dt> + <dd>Ask each tool invoked by the makefiles to print out what it is doing on + the standard output. This also implies <tt>VERBOSE=1</tt>. + <br><br></dd> +</dl> + +<p>Every directory in the LLVM object tree includes a <tt>Makefile</tt> to build +it and any subdirectories that it contains. Entering any directory inside the +LLVM object tree and typing <tt>gmake</tt> should rebuild anything in or below +that directory that is out of date.</p> + +</div> + +<!-- ======================================================================= --> +<div class="doc_subsection"> + <a name="cross-compile">Cross-Compiling LLVM</a> +</div> + +<div class="doc_text"> + <p>It is possible to cross-compile LLVM itself. That is, you can create LLVM + executables and libraries to be hosted on a platform different from the + platform where they are build (a Canadian Cross build). To configure a + cross-compile, supply the configure script with <tt>--build</tt> and + <tt>--host</tt> options that are different. The values of these options must + be legal target triples that your GCC compiler supports.</p> + + <p>The result of such a build is executables that are not runnable on + on the build host (--build option) but can be executed on the compile host + (--host option).</p> +</div> + +<!-- ======================================================================= --> +<div class="doc_subsection"> + <a name="objfiles">The Location of LLVM Object Files</a> +</div> + +<div class="doc_text"> + +<p>The LLVM build system is capable of sharing a single LLVM source tree among +several LLVM builds. Hence, it is possible to build LLVM for several different +platforms or configurations using the same source tree.</p> + +<p>This is accomplished in the typical autoconf manner:</p> + +<ul> + <li><p>Change directory to where the LLVM object files should live:</p> + + <div class="doc_code"><pre>% cd <i>OBJ_ROOT</i></pre></div></li> + + <li><p>Run the <tt>configure</tt> script found in the LLVM source + directory:</p> + + <div class="doc_code"><pre>% <i>SRC_ROOT</i>/configure</pre></div></li> +</ul> + +<p>The LLVM build will place files underneath <i>OBJ_ROOT</i> in directories +named after the build type:</p> + +<dl> + <dt>Debug Builds + <dd> + <dl> + <dt>Tools + <dd><tt><i>OBJ_ROOT</i>/Debug/bin</tt> + <dt>Libraries + <dd><tt><i>OBJ_ROOT</i>/Debug/lib</tt> + </dl> + <br><br> + + <dt>Release Builds + <dd> + <dl> + <dt>Tools + <dd><tt><i>OBJ_ROOT</i>/Release/bin</tt> + <dt>Libraries + <dd><tt><i>OBJ_ROOT</i>/Release/lib</tt> + </dl> + <br><br> + + <dt>Profile Builds + <dd> + <dl> + <dt>Tools + <dd><tt><i>OBJ_ROOT</i>/Profile/bin</tt> + <dt>Libraries + <dd><tt><i>OBJ_ROOT</i>/Profile/lib</tt> + </dl> +</dl> + +</div> + +<!-- ======================================================================= --> +<div class="doc_subsection"> + <a name="optionalconfig">Optional Configuration Items</a> +</div> + +<div class="doc_text"> + +<p> +If you're running on a Linux system that supports the "<a +href="http://www.tat.physik.uni-tuebingen.de/~rguenth/linux/binfmt_misc.html">binfmt_misc</a>" +module, and you have root access on the system, you can set your system up to +execute LLVM bitcode files directly. To do this, use commands like this (the +first command may not be required if you are already using the module):</p> + +<div class="doc_code"> +<pre> +$ mount -t binfmt_misc none /proc/sys/fs/binfmt_misc +$ echo ':llvm:M::BC::/path/to/lli:' > /proc/sys/fs/binfmt_misc/register +$ chmod u+x hello.bc (if needed) +$ ./hello.bc +</pre> +</div> + +<p> +This allows you to execute LLVM bitcode files directly. On Debian, you +can also use this command instead of the 'echo' command above:</p> +</p> + +<div class="doc_code"> +<pre> +$ sudo update-binfmts --install llvm /path/to/lli --magic 'BC' +</pre> +</div> + +</div> + +<!-- *********************************************************************** --> +<div class="doc_section"> + <a name="layout"><b>Program Layout</b></a> +</div> +<!-- *********************************************************************** --> + +<div class="doc_text"> + +<p>One useful source of information about the LLVM source base is the LLVM <a +href="http://www.doxygen.org">doxygen</a> documentation available at <tt><a +href="http://llvm.org/doxygen/">http://llvm.org/doxygen/</a></tt>. +The following is a brief introduction to code layout:</p> + +</div> + +<!-- ======================================================================= --> +<div class="doc_subsection"><a name="examples"><tt>llvm/examples</tt></a></div> +<div class="doc_text"> + <p>This directory contains some simple examples of how to use the LLVM IR and + JIT.</p> +</div> + +<!-- ======================================================================= --> +<div class="doc_subsection"><a name="include"><tt>llvm/include</tt></a></div> +<div class="doc_text"> + +<p>This directory contains public header files exported from the LLVM +library. The three main subdirectories of this directory are:</p> + +<dl> + <dt><tt><b>llvm/include/llvm</b></tt></dt> + <dd>This directory contains all of the LLVM specific header files. This + directory also has subdirectories for different portions of LLVM: + <tt>Analysis</tt>, <tt>CodeGen</tt>, <tt>Target</tt>, <tt>Transforms</tt>, + etc...</dd> + + <dt><tt><b>llvm/include/llvm/Support</b></tt></dt> + <dd>This directory contains generic support libraries that are provided with + LLVM but not necessarily specific to LLVM. For example, some C++ STL utilities + and a Command Line option processing library store their header files here. + </dd> + + <dt><tt><b>llvm/include/llvm/Config</b></tt></dt> + <dd>This directory contains header files configured by the <tt>configure</tt> + script. They wrap "standard" UNIX and C header files. Source code can + include these header files which automatically take care of the conditional + #includes that the <tt>configure</tt> script generates.</dd> +</dl> +</div> + +<!-- ======================================================================= --> +<div class="doc_subsection"><a name="lib"><tt>llvm/lib</tt></a></div> +<div class="doc_text"> + +<p>This directory contains most of the source files of the LLVM system. In LLVM, +almost all code exists in libraries, making it very easy to share code among the +different <a href="#tools">tools</a>.</p> + +<dl> + <dt><tt><b>llvm/lib/VMCore/</b></tt></dt> + <dd> This directory holds the core LLVM source files that implement core + classes like Instruction and BasicBlock.</dd> + + <dt><tt><b>llvm/lib/AsmParser/</b></tt></dt> + <dd>This directory holds the source code for the LLVM assembly language parser + library.</dd> + + <dt><tt><b>llvm/lib/BitCode/</b></tt></dt> + <dd>This directory holds code for reading and write LLVM bitcode.</dd> + + <dt><tt><b>llvm/lib/Analysis/</b></tt><dd>This directory contains a variety of + different program analyses, such as Dominator Information, Call Graphs, + Induction Variables, Interval Identification, Natural Loop Identification, + etc.</dd> + + <dt><tt><b>llvm/lib/Transforms/</b></tt></dt> + <dd> This directory contains the source code for the LLVM to LLVM program + transformations, such as Aggressive Dead Code Elimination, Sparse Conditional + Constant Propagation, Inlining, Loop Invariant Code Motion, Dead Global + Elimination, and many others.</dd> + + <dt><tt><b>llvm/lib/Target/</b></tt></dt> + <dd> This directory contains files that describe various target architectures + for code generation. For example, the <tt>llvm/lib/Target/X86</tt> + directory holds the X86 machine description while + <tt>llvm/lib/Target/CBackend</tt> implements the LLVM-to-C converter.</dd> + + <dt><tt><b>llvm/lib/CodeGen/</b></tt></dt> + <dd> This directory contains the major parts of the code generator: Instruction + Selector, Instruction Scheduling, and Register Allocation.</dd> + + <dt><tt><b>llvm/lib/Debugger/</b></tt></dt> + <dd> This directory contains the source level debugger library that makes + it possible to instrument LLVM programs so that a debugger could identify + source code locations at which the program is executing.</dd> + + <dt><tt><b>llvm/lib/ExecutionEngine/</b></tt></dt> + <dd> This directory contains libraries for executing LLVM bitcode directly + at runtime in both interpreted and JIT compiled fashions.</dd> + + <dt><tt><b>llvm/lib/Support/</b></tt></dt> + <dd> This directory contains the source code that corresponds to the header + files located in <tt>llvm/include/Support/</tt>.</dd> + + <dt><tt><b>llvm/lib/System/</b></tt></dt> + <dd>This directory contains the operating system abstraction layer that + shields LLVM from platform-specific coding.</dd> +</dl> + +</div> + +<!-- ======================================================================= --> +<div class="doc_subsection"><a name="projects"><tt>llvm/projects</tt></a></div> +<div class="doc_text"> + <p>This directory contains projects that are not strictly part of LLVM but are + shipped with LLVM. This is also the directory where you should create your own + LLVM-based projects. See <tt>llvm/projects/sample</tt> for an example of how + to set up your own project.</p> +</div> + +<!-- ======================================================================= --> +<div class="doc_subsection"><a name="runtime"><tt>llvm/runtime</tt></a></div> +<div class="doc_text"> + +<p>This directory contains libraries which are compiled into LLVM bitcode and +used when linking programs with the GCC front end. Most of these libraries are +skeleton versions of real libraries; for example, libc is a stripped down +version of glibc.</p> + +<p>Unlike the rest of the LLVM suite, this directory needs the LLVM GCC front +end to compile.</p> + +</div> + +<!-- ======================================================================= --> +<div class="doc_subsection"><a name="test"><tt>llvm/test</tt></a></div> +<div class="doc_text"> + <p>This directory contains feature and regression tests and other basic sanity + checks on the LLVM infrastructure. These are intended to run quickly and cover + a lot of territory without being exhaustive.</p> +</div> + +<!-- ======================================================================= --> +<div class="doc_subsection"><a name="llvmtest"><tt>test-suite</tt></a></div> +<div class="doc_text"> + <p>This is not a directory in the normal llvm module; it is a separate + Subversion + module that must be checked out (usually to <tt>projects/test-suite</tt>). + This + module contains a comprehensive correctness, performance, and benchmarking + test + suite for LLVM. It is a separate Subversion module because not every LLVM + user is + interested in downloading or building such a comprehensive test suite. For + further details on this test suite, please see the + <a href="TestingGuide.html">Testing Guide</a> document.</p> +</div> + +<!-- ======================================================================= --> +<div class="doc_subsection"><a name="tools"><tt>llvm/tools</tt></a></div> +<div class="doc_text"> + +<p>The <b>tools</b> directory contains the executables built out of the +libraries above, which form the main part of the user interface. You can +always get help for a tool by typing <tt>tool_name -help</tt>. The +following is a brief introduction to the most important tools. More detailed +information is in the <a href="CommandGuide/index.html">Command Guide</a>.</p> + +<dl> + + <dt><tt><b>bugpoint</b></tt></dt> + <dd><tt>bugpoint</tt> is used to debug + optimization passes or code generation backends by narrowing down the + given test case to the minimum number of passes and/or instructions that + still cause a problem, whether it is a crash or miscompilation. See <a + href="HowToSubmitABug.html">HowToSubmitABug.html</a> for more information + on using <tt>bugpoint</tt>.</dd> + + <dt><tt><b>llvmc</b></tt></dt> + <dd>The LLVM Compiler Driver. This program can + be configured to utilize both LLVM and non-LLVM compilation tools to enable + pre-processing, translation, optimization, assembly, and linking of programs + all from one command line. <tt>llvmc</tt> also takes care of processing the + dependent libraries found in bitcode. This reduces the need to get the + traditional <tt>-l<name></tt> options right on the command line. Please + note that this tool, while functional, is still experimental and not feature + complete.</dd> + + <dt><tt><b>llvm-ar</b></tt></dt> + <dd>The archiver produces an archive containing + the given LLVM bitcode files, optionally with an index for faster + lookup.</dd> + + <dt><tt><b>llvm-as</b></tt></dt> + <dd>The assembler transforms the human readable LLVM assembly to LLVM + bitcode.</dd> + + <dt><tt><b>llvm-dis</b></tt></dt> + <dd>The disassembler transforms the LLVM bitcode to human readable + LLVM assembly.</dd> + + <dt><tt><b>llvm-ld</b></tt></dt> + <dd><tt>llvm-ld</tt> is a general purpose and extensible linker for LLVM. + This is the linker invoked by <tt>llvmc</tt>. It performsn standard link time + optimizations and allows optimization modules to be loaded and run so that + language specific optimizations can be applied at link time.</dd> + + <dt><tt><b>llvm-link</b></tt></dt> + <dd><tt>llvm-link</tt>, not surprisingly, links multiple LLVM modules into + a single program.</dd> + + <dt><tt><b>lli</b></tt></dt> + <dd><tt>lli</tt> is the LLVM interpreter, which + can directly execute LLVM bitcode (although very slowly...). For architectures + that support it (currently x86, Sparc, and PowerPC), by default, <tt>lli</tt> + will function as a Just-In-Time compiler (if the functionality was compiled + in), and will execute the code <i>much</i> faster than the interpreter.</dd> + + <dt><tt><b>llc</b></tt></dt> + <dd> <tt>llc</tt> is the LLVM backend compiler, which + translates LLVM bitcode to a native code assembly file or to C code (with + the -march=c option).</dd> + + <dt><tt><b>llvm-gcc</b></tt></dt> + <dd><tt>llvm-gcc</tt> is a GCC-based C frontend that has been retargeted to + use LLVM as its backend instead of GCC's RTL backend. It can also emit LLVM + bitcode or assembly (with the <tt>-emit-llvm</tt> option) instead of the + usual machine code output. It works just like any other GCC compiler, + taking the typical <tt>-c, -S, -E, -o</tt> options that are typically used. + Additionally, the the source code for <tt>llvm-gcc</tt> is available as a + separate Subversion module.</dd> + + <dt><tt><b>opt</b></tt></dt> + <dd><tt>opt</tt> reads LLVM bitcode, applies a series of LLVM to LLVM + transformations (which are specified on the command line), and then outputs + the resultant bitcode. The '<tt>opt -help</tt>' command is a good way to + get a list of the program transformations available in LLVM.<br> + <dd><tt>opt</tt> can also be used to run a specific analysis on an input + LLVM bitcode file and print out the results. It is primarily useful for + debugging analyses, or familiarizing yourself with what an analysis does.</dd> +</dl> +</div> + +<!-- ======================================================================= --> +<div class="doc_subsection"><a name="utils"><tt>llvm/utils</tt></a></div> +<div class="doc_text"> + +<p>This directory contains utilities for working with LLVM source code, and some +of the utilities are actually required as part of the build process because they +are code generators for parts of LLVM infrastructure.</p> + +<dl> + <dt><tt><b>codegen-diff</b></tt> <dd><tt>codegen-diff</tt> is a script + that finds differences between code that LLC generates and code that LLI + generates. This is a useful tool if you are debugging one of them, + assuming that the other generates correct output. For the full user + manual, run <tt>`perldoc codegen-diff'</tt>.<br><br> + + <dt><tt><b>emacs/</b></tt> <dd>The <tt>emacs</tt> directory contains + syntax-highlighting files which will work with Emacs and XEmacs editors, + providing syntax highlighting support for LLVM assembly files and TableGen + description files. For information on how to use the syntax files, consult + the <tt>README</tt> file in that directory.<br><br> + + <dt><tt><b>getsrcs.sh</b></tt> <dd>The <tt>getsrcs.sh</tt> script finds + and outputs all non-generated source files, which is useful if one wishes + to do a lot of development across directories and does not want to + individually find each file. One way to use it is to run, for example: + <tt>xemacs `utils/getsources.sh`</tt> from the top of your LLVM source + tree.<br><br> + + <dt><tt><b>llvmgrep</b></tt></dt> + <dd>This little tool performs an "egrep -H -n" on each source file in LLVM and + passes to it a regular expression provided on <tt>llvmgrep</tt>'s command + line. This is a very efficient way of searching the source base for a + particular regular expression.</dd> + + <dt><tt><b>makellvm</b></tt> <dd>The <tt>makellvm</tt> script compiles all + files in the current directory and then compiles and links the tool that + is the first argument. For example, assuming you are in the directory + <tt>llvm/lib/Target/Sparc</tt>, if <tt>makellvm</tt> is in your path, + simply running <tt>makellvm llc</tt> will make a build of the current + directory, switch to directory <tt>llvm/tools/llc</tt> and build it, + causing a re-linking of LLC.<br><br> + + <dt><tt><b>NewNightlyTest.pl</b></tt> and + <tt><b>NightlyTestTemplate.html</b></tt> <dd>These files are used in a + cron script to generate nightly status reports of the functionality of + tools, and the results can be seen by following the appropriate link on + the <a href="http://llvm.org/">LLVM homepage</a>.<br><br> + + <dt><tt><b>TableGen/</b></tt> <dd>The <tt>TableGen</tt> directory contains + the tool used to generate register descriptions, instruction set + descriptions, and even assemblers from common TableGen description + files.<br><br> + + <dt><tt><b>vim/</b></tt> <dd>The <tt>vim</tt> directory contains + syntax-highlighting files which will work with the VIM editor, providing + syntax highlighting support for LLVM assembly files and TableGen + description files. For information on how to use the syntax files, consult + the <tt>README</tt> file in that directory.<br><br> + +</dl> + +</div> + +<!-- ======================================================================= --> +<div class="doc_subsection"><a name="win32"><tt>llvm/win32</tt></a></div> +<div class="doc_text"> + <p>This directory contains build scripts and project files for use with + Visual C++. This allows developers on Windows to build LLVM without the need + for Cygwin. The contents of this directory should be considered experimental + at this time. + </p> +</div> +<!-- *********************************************************************** --> +<div class="doc_section"> + <a name="tutorial">An Example Using the LLVM Tool Chain</a> +</div> +<!-- *********************************************************************** --> + +<div class="doc_text"> +<p>This section gives an example of using LLVM. llvm-gcc3 is now obsolete, +so we only include instructions for llvm-gcc4. +</p> + +<p><b>Note:</b> The <i>gcc4</i> frontend's invocation is <b><i>considerably different</i></b> +from the previous <i>gcc3</i> frontend. In particular, the <i>gcc4</i> frontend <b><i>does not</i></b> +create bitcode by default: <i>gcc4</i> produces native code. As the example below illustrates, +the '--emit-llvm' flag is needed to produce LLVM bitcode output. For <i>makefiles</i> and +<i>configure</i> scripts, the CFLAGS variable needs '--emit-llvm' to produce bitcode +output.</p> +</div> + +<!-- ======================================================================= --> +<div class="doc_subsection"><a name="tutorial4">Example with llvm-gcc4</a></div> + +<div class="doc_text"> + +<ol> + <li><p>First, create a simple C file, name it 'hello.c':</p> + +<div class="doc_code"> +<pre> +#include <stdio.h> + +int main() { + printf("hello world\n"); + return 0; +} +</pre></div></li> + + <li><p>Next, compile the C file into a native executable:</p> + + <div class="doc_code"><pre>% llvm-gcc hello.c -o hello</pre></div> + + <p>Note that llvm-gcc works just like GCC by default. The standard -S and + -c arguments work as usual (producing a native .s or .o file, + respectively).</p></li> + + <li><p>Next, compile the C file into a LLVM bitcode file:</p> + + <div class="doc_code"> + <pre>% llvm-gcc -O3 -emit-llvm hello.c -c -o hello.bc</pre></div> + + <p>The -emit-llvm option can be used with the -S or -c options to emit an + LLVM ".ll" or ".bc" file (respectively) for the code. This allows you + to use the <a href="CommandGuide/index.html">standard LLVM tools</a> on + the bitcode file.</p> + + <p>Unlike llvm-gcc3, llvm-gcc4 correctly responds to -O[0123] arguments. + </p></li> + + <li><p>Run the program in both forms. To run the program, use:</p> + + <div class="doc_code"><pre>% ./hello</pre></div> + + <p>and</p> + + <div class="doc_code"><pre>% lli hello.bc</pre></div> + + <p>The second examples shows how to invoke the LLVM JIT, <a + href="CommandGuide/html/lli.html">lli</a>.</p></li> + + <li><p>Use the <tt>llvm-dis</tt> utility to take a look at the LLVM assembly + code:</p> + +<div class="doc_code"> +<pre>llvm-dis < hello.bc | less</pre> +</div></li> + + <li><p>Compile the program to native assembly using the LLC code + generator:</p> + + <div class="doc_code"><pre>% llc hello.bc -o hello.s</pre></div></li> + + <li><p>Assemble the native assembly language file into a program:</p> + +<div class="doc_code"> +<pre> +<b>Solaris:</b> % /opt/SUNWspro/bin/cc -xarch=v9 hello.s -o hello.native + +<b>Others:</b> % gcc hello.s -o hello.native +</pre> +</div></li> + + <li><p>Execute the native code program:</p> + + <div class="doc_code"><pre>% ./hello.native</pre></div> + + <p>Note that using llvm-gcc to compile directly to native code (i.e. when + the -emit-llvm option is not present) does steps 6/7/8 for you.</p> + </li> + +</ol> + +</div> + + +<!-- *********************************************************************** --> +<div class="doc_section"> + <a name="problems">Common Problems</a> +</div> +<!-- *********************************************************************** --> + +<div class="doc_text"> + +<p>If you are having problems building or using LLVM, or if you have any other +general questions about LLVM, please consult the <a href="FAQ.html">Frequently +Asked Questions</a> page.</p> + +</div> + +<!-- *********************************************************************** --> +<div class="doc_section"> + <a name="links">Links</a> +</div> +<!-- *********************************************************************** --> + +<div class="doc_text"> + +<p>This document is just an <b>introduction</b> on how to use LLVM to do +some simple things... there are many more interesting and complicated things +that you can do that aren't documented here (but we'll gladly accept a patch +if you want to write something up!). For more information about LLVM, check +out:</p> + +<ul> + <li><a href="http://llvm.org/">LLVM homepage</a></li> + <li><a href="http://llvm.org/doxygen/">LLVM doxygen tree</a></li> + <li><a href="http://llvm.org/docs/Projects.html">Starting a Project + that Uses LLVM</a></li> +</ul> + +</div> + +<!-- *********************************************************************** --> + +<hr> +<address> + <a href="http://jigsaw.w3.org/css-validator/check/referer"><img + src="http://jigsaw.w3.org/css-validator/images/vcss-blue" alt="Valid CSS"></a> + <a href="http://validator.w3.org/check/referer"><img + src="http://www.w3.org/Icons/valid-html401-blue" alt="Valid HTML 4.01"></a> + + <a href="mailto:sabre@nondot.org">Chris Lattner</a><br> + <a href="http://llvm.x10sys.com/rspencer/">Reid Spencer</a><br> + <a href="http://llvm.org">The LLVM Compiler Infrastructure</a><br> + Last modified: $Date$ +</address> +</body> +</html> |