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| <title>Getting Started with LLVM System</title> |
| </head> |
| |
| <body bgcolor=white> |
| <center><h1>Getting Started with the LLVM System<br><font size=3>By: <a |
| href="mailto:[email protected]">Guochun Shi</a>, |
| <a href="mailto:[email protected]">Chris Lattner</a>, |
| <a href="mailto:[email protected]">John Criswell</a>, |
| <a href="http://misha.brukman.net">Misha Brukman</a>, and |
| <a href="http://www.cs.uiuc.edu/~vadve">Vikram Adve</a> |
| </font></h1></center> |
| |
| <!--=====================================================================--> |
| <h2><a name="Contents">Contents</a></h2> |
| <!--=====================================================================--> |
| |
| <ul> |
| <li><a href="#overview">Overview</a> |
| <li><a href="#quickstart">Getting Started Quickly (A Summary)</a> |
| <li><a href="#requirements">Requirements</a> |
| <ol> |
| <li><a href="#hardware">Hardware</a> |
| <li><a href="#software">Software</a> |
| </ol> |
| |
| <li><a href="#starting">Getting Started with LLVM</a> |
| <ol> |
| <li><a href="#terminology">Terminology and Notation</tt></a> |
| <li><a href="#environment">Setting Up Your Environment</a> |
| <li><a href="#unpack">Unpacking the LLVM Archives</a> |
| <li><a href="#checkout">Checkout LLVM from CVS</a> |
| <li><a href="#installcf">Install the GCC Front End</a> |
| <li><a href="#config">Local LLVM Configuration</tt></a> |
| <li><a href="#compile">Compiling the LLVM Suite Source Code</a> |
| <li><a href="#objfiles">The Location of LLVM Object Files</tt></a> |
| </ol> |
| <li><a href="#layout">Program layout</a> |
| <ol> |
| <li><a href="#cvsdir"><tt>CVS</tt> directories</a> |
| <li><a href="#include"><tt>llvm/include</tt></a> |
| <li><a href="#lib"><tt>llvm/lib</tt></a> |
| <li><a href="#runtime"><tt>llvm/runtime</tt></a> |
| <li><a href="#test"><tt>llvm/test</tt></a> |
| <li><a href="#tools"><tt>llvm/tools</tt></a> |
| <li><a href="#utils"><tt>llvm/utils</tt></a> |
| </ol> |
| <li><a href="#tutorial">An Example Using the LLVM Tool Chain</a> |
| <li><a href="#problems">Common Problems</a> |
| <li><a href="#links">Links</a> |
| </ul> |
| |
| |
| <!--=====================================================================--> |
| <center> |
| <h2><a name="overview"><b>Overview</b></a></h2> |
| </center> |
| <hr> |
| <!--=====================================================================--> |
| |
| Welcome to LLVM! In order to get started, you first need to know some |
| basic information. |
| |
| <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, |
| bytecode analyzer, and bytecode optimizer. It also contains a test suite |
| that can be used to test the LLVM tools and the GCC front end. |
| <p> |
| The second piece is the GCC front end. This component provides a version |
| of GCC that compiles C and C++ code into LLVM bytecode. Currently, the |
| GCC front end is a modified version of GCC 3.4 (we track the GCC 3.4 |
| development). Once compiled into LLVM bytecode, a program can be |
| manipulated with the LLVM tools from the LLVM suite. |
| |
| <!--=====================================================================--> |
| <center> |
| <h2><a name="quickstart"><b>Getting Started Quickly (A Summary)</b></a></h2> |
| </center> |
| <hr> |
| <!--=====================================================================--> |
| |
| Here's the short story for getting up and running quickly with LLVM: |
| <ol> |
| <li>Install the GCC front end: |
| <ol> |
| <li><tt>cd <i>where-you-want-the-C-front-end-to-live</i></tt> |
| <li><tt>gunzip --stdout cfrontend.<i>platform</i>.tar.gz | tar -xvf |
| -</tt> |
| </ol> |
| |
| <p> |
| |
| <li>Get the Source Code |
| <ul> |
| <li>With the distributed files: |
| <ol> |
| <li><tt>cd <i>where-you-want-llvm-to-live</i></tt> |
| <li><tt>gunzip --stdout llvm.tar.gz | tar -xvf -</tt> |
| <li><tt>cd llvm</tt> |
| </ol> |
| |
| <p> |
| |
| <li>With anonymous CVS access: |
| <ol> |
| <li><tt>cd <i>where-you-want-llvm-to-live</i></tt> |
| <li><tt>cvs -d :pserver:[email protected]:/var/cvs/llvm login</tt> |
| <li>Hit the return key when prompted for the password. |
| <li><tt>cvs -z3 -d :pserver:[email protected]:/var/cvs/llvm co llvm</tt> |
| <li><tt>cd llvm</tt> |
| </ol> |
| </ul> |
| </ul> |
| |
| <p> |
| |
| <li>Configure the LLVM Build Environment |
| <ol> |
| <li>Change directory to where you want to store the LLVM object |
| files and run <tt>configure</tt> to configure the Makefiles and |
| header files for the default platform. |
| Useful options include: |
| <ul> |
| <li><tt>--with-llvmgccdir=<i>directory</i></tt> |
| <br> |
| Specify where the LLVM GCC frontend is installed. |
| <p> |
| |
| <li><tt>--enable-spec2000=<i>directory</i></tt> |
| <br> |
| Enable the SPEC2000 benchmarks for testing. The SPEC2000 |
| benchmarks should be available in <tt><i>directory</i></tt>. |
| </ul> |
| </ol> |
| |
| <p> |
| |
| <li>Build the LLVM Suite |
| <ol> |
| <li>Set your LLVM_LIB_SEARCH_PATH environment variable. |
| <li><tt>gmake -k |& tee gnumake.out |
| # this is csh or tcsh syntax</tt> |
| </ol> |
| |
| <p> |
| |
| </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. |
| |
| <!--=====================================================================--> |
| <center> |
| <h2><a name="requirements"><b>Requirements</b></a></h2> |
| </center> |
| <hr> |
| <!--=====================================================================--> |
| |
| 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. |
| |
| <!--=====================================================================--> |
| <h3><a name="hardware"><b>Hardware</b></a></h3> |
| <!--=====================================================================--> |
| LLVM is known to work on the following platforms: |
| <ul> |
| <li> Linux on x86 (Pentium and above) |
| <ul> |
| <li> Approximately 760 MB of Free Disk Space |
| <ul> |
| <li>Source code: 30 MB |
| <li>Object code: 670 MB |
| <li>GCC front end: 60 MB |
| </ul> |
| </ul> |
| |
| <p> |
| |
| <li> Solaris on SparcV9 (Ultrasparc) |
| <ul> |
| <li> Approximately 1.24 GB of Free Disk Space |
| <ul> |
| <li>Source code: 30 MB |
| <li>Object code: 1000 MB |
| <li>GCC front end: 210 MB |
| </ul> |
| </ul> |
| </ul> |
| |
| 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 |
| bytecode. Code generation should work as well, although the generated |
| native code may not work on your platform. |
| <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 always request |
| <a href="mailto:[email protected]">a copy of the source</a> |
| and try to compile it on your platform. |
| </p> |
| |
| <!--=====================================================================--> |
| <h3><a name="software"><b>Software</b></a></h3> |
| <!--=====================================================================--> |
| <p> |
| |
| Compiling LLVM requires that you have several software packages installed: |
| |
| <ul compact> |
| <li> |
| <a href="http://gcc.gnu.org">GCC 3.x with C and C++ language support</a> |
| |
| <li> |
| <a href="http://savannah.gnu.org/projects/make">GNU Make</a> |
| |
| <li> |
| <a href="http://www.gnu.org/software/flex">Flex</a> |
| |
| <li> |
| <a href="http://www.gnu.org/software/bison/bison.html">Bison</a> |
| </ul> |
| |
| <p> |
| There are some additional tools that you may want to have when working with |
| LLVM: |
| </p> |
| |
| <ul> |
| <li><A href="http://www.gnu.org/software/autoconf">GNU Autoconf</A> |
| <li><A href="http://savannah.gnu.org/projects/m4">GNU M4</A> |
| <p> |
| If you want to make changes to the configure scripts, you will need |
| GNU autoconf (2.57 or higher), and consequently, GNU M4 (version 1.4 |
| or higher). |
| </p> |
| |
| <li><A href="http://www.codesourcery.com/qm/qmtest">QMTest</A> |
| <li><A href="http://www.python.org">Python</A> |
| <p> |
| These are needed to use the LLVM test suite. |
| </ul> |
| |
| |
| <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. |
| A <a href="#starting">complete guide to installation</a> is provided in the |
| next section. |
| |
| <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. |
| |
| <!--=====================================================================--> |
| <center> |
| <h2><a name="starting"><b>Getting Started with LLVM</b></a></h2> |
| </center> |
| <hr> |
| <!--=====================================================================--> |
| |
| <!-------------------------------------------------------------------------> |
| <h3><a name="terminology">Terminology and Notation</a></h3> |
| <!-------------------------------------------------------------------------> |
| |
| <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 compact> |
| <dt>SRC_ROOT |
| <dd> |
| This is the top level directory of the LLVM source tree. |
| <p> |
| |
| <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). |
| <p> |
| |
| <dt>LLVMGCCDIR |
| <dd> |
| This is the where the LLVM GCC Front End is installed. |
| <p> |
| For the pre-built GCC front end binaries, the LLVMGCCDIR is |
| <tt>cfrontend/<i>platform</i>/llvm-gcc</tt>. |
| </dl> |
| |
| <!-------------------------------------------------------------------------> |
| <h3><a name="environment">Setting Up Your Environment</a></h3> |
| <!-------------------------------------------------------------------------> |
| |
| <p> |
| In order to compile and use LLVM, you will need to set some environment |
| variables. There are also some shell aliases which you may find useful. |
| You can set these on the command line, or better yet, set them in your |
| <tt>.cshrc</tt> or <tt>.profile</tt>. |
| |
| <dl compact> |
| <dt><tt>LLVM_LIB_SEARCH_PATH</tt>=<tt><i>LLVMGCCDIR</i>/llvm-gcc/bytecode-libs</tt> |
| <dd> |
| This environment variable helps the LLVM GCC front end find bytecode |
| libraries that it will need for compilation. |
| <p> |
| |
| <dt>alias llvmgcc <i>LLVMGCCDIR</i><tt>/llvm-gcc/bin/gcc</tt> |
| <dt>alias llvmg++ <i>LLVMGCCDIR</i><tt>/llvm-gcc/bin/g++</tt> |
| <dd> |
| This alias allows you to use the LLVM C and C++ front ends without putting |
| them in your <tt>PATH</tt> or typing in their complete pathnames. |
| </dl> |
| |
| <!-------------------------------------------------------------------------> |
| <h3><a name="unpack">Unpacking the LLVM Archives</a></h3> |
| <!-------------------------------------------------------------------------> |
| |
| <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 three files. Each |
| file is a TAR archive that is compressed with the gzip program. |
| </p> |
| |
| <p> The three files are as follows: |
| <dl compact> |
| <dt>llvm.tar.gz |
| <dd>This is the source code to the LLVM suite. |
| <p> |
| |
| <dt>cfrontend.sparc.tar.gz |
| <dd>This is the binary release of the GCC front end for Solaris/Sparc. |
| <p> |
| |
| <dt>cfrontend.x86.tar.gz |
| <dd>This is the binary release of the GCC front end for Linux/x86. |
| </dl> |
| |
| <!-------------------------------------------------------------------------> |
| <h3><a name="checkout">Checkout LLVM from CVS</a></h3> |
| <!-------------------------------------------------------------------------> |
| |
| <p>If you have access to our CVS repository, you can get a fresh copy of |
| the entire source code. All you need to do is check it out from CVS as |
| follows: |
| <ul> |
| <li><tt>cd <i>where-you-want-llvm-to-live</i></tt> |
| <li><tt>cvs -d :pserver:[email protected]:/var/cvs/llvm login</tt> |
| <li>Hit the return key when prompted for the password. |
| <li><tt>cvs -z3 -d :pserver:[email protected]:/var/cvs/llvm co llvm</tt> |
| </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> |
| Note that the GCC front end is not included in the CVS repository. You |
| should have downloaded the binary distribution for your platform. |
| </p> |
| |
| <!-------------------------------------------------------------------------> |
| <h3><a name="installcf">Install the GCC Front End</a></h3> |
| <!-------------------------------------------------------------------------> |
| |
| <p> |
| Before configuring and compiling the LLVM suite, you need to extract the |
| LLVM GCC front end from the binary distribution. It is used for building the |
| bytecode libraries later used by the GCC front end for linking programs, and |
| its location must be specified when the LLVM suite is configured. |
| </p> |
| |
| <p> |
| To install the GCC front end, do the following: |
| <ol> |
| <li><tt>cd <i>where-you-want-the-front-end-to-live</i></tt> |
| <li><tt>gunzip --stdout cfrontend.<i>platform</i>.tar.gz | tar -xvf |
| -</tt> |
| </ol> |
| |
| <!-------------------------------------------------------------------------> |
| <h3><a name="config">Local LLVM Configuration</a></h3> |
| <!-------------------------------------------------------------------------> |
| |
| <p>Once checked out from the CVS repository, the LLVM suite source code |
| must be configured via the <tt>configure</tt> script. This script sets |
| variables in <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 build LLVM. |
| |
| <p> |
| The following environment variables are used by the <tt>configure</tt> |
| script to configure the build system: |
| </p> |
| |
| <table border=1> |
| <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 compact> |
| <dt><i>--with-llvmgccdir=LLVMGCCDIR</i> |
| <dd> |
| Path to the location where the LLVM C front end binaries and |
| associated libraries will be installed. |
| <p> |
| <dt><i>--enable-optimized</i> |
| <dd> |
| Enables optimized compilation by default (debugging symbols are removed |
| and GCC optimization flags are enabled). The default is to use an |
| unoptimized build (also known as a debug build). |
| <p> |
| <dt><i>--enable-jit</i> |
| <dd> |
| Compile the Just In Time (JIT) 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. |
| <p> |
| <dt><i>--enable-spec2000</i> |
| <dt><i>--enable-spec2000=<<tt>directory</tt>></i> |
| <dd> |
| Enable the use of SPEC2000 when testing LLVM. This is disabled by default |
| (unless <tt>configure</tt> finds SPEC2000 installed). By specifying |
| <tt>directory</tt>, you can tell configure where to find the SPEC2000 |
| benchmarks. If <tt>directory</tt> is left unspecified, <tt>configure</tt> |
| uses the default value |
| <tt>/home/vadve/shared/benchmarks/speccpu2000/benchspec</tt>. |
| </dl> |
| |
| <p> |
| To configure LLVM, follow these steps: |
| <ol> |
| <li>Change directory into the object root directory: |
| <br> |
| <tt>cd <i>OBJ_ROOT</i></tt> |
| <p> |
| |
| <li>Run the <tt>configure</tt> script located in the LLVM source tree: |
| <br> |
| <tt><i>SRC_ROOT</i>/configure</tt> |
| <p> |
| </ol> |
| </p> |
| |
| In addition to running <tt>configure</tt>, you must set the |
| <tt>LLVM_LIB_SEARCH_PATH</tt> environment variable in your startup scripts. |
| This environment variable is used to locate "system" libraries like |
| "<tt>-lc</tt>" and "<tt>-lm</tt>" when linking. This variable should be set |
| to the absolute path for the bytecode-libs subdirectory of the GCC front end |
| install, or <i>LLVMGCCDIR</i>/llvm-gcc/bytecode-libs. For example, one might |
| set <tt>LLVM_LIB_SEARCH_PATH</tt> to |
| <tt>/home/vadve/lattner/local/x86/llvm-gcc/bytecode-libs</tt> for the X86 |
| version of the GCC front end on our research machines.<p> |
| |
| <!-------------------------------------------------------------------------> |
| <h3><a name="compile">Compiling the LLVM Suite Source Code</a></h3> |
| <!-------------------------------------------------------------------------> |
| |
| Once you have configured LLVM, you can build it. There are three types of |
| builds: |
| |
| <dl compact> |
| <dt>Debug Builds |
| <dd> |
| These builds are the default when one 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. |
| <p> |
| |
| <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. |
| <p> |
| |
| <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> |
| |
| Once you have LLVM configured, you can build it by entering the |
| <i>OBJ_ROOT</i> directory and issuing the following command: |
| <p> |
| <tt>gmake</tt> |
| |
| <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> |
| |
| <p> |
| <tt>gmake -j2</tt> |
| |
| <p> |
| There are several special targets which are useful when working with the LLVM |
| source code: |
| |
| <dl compact> |
| <dt><tt>gmake clean</tt> |
| <dd> |
| Removes all files generated by the build. This includes object files, |
| generated C/C++ files, libraries, and executables. |
| <p> |
| |
| <dt><tt>gmake distclean</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. |
| <p> |
| |
| <dt><tt>gmake install</tt> |
| <dd> |
| Installs LLVM files into the proper location. For the most part, |
| this does nothing, but it does install bytecode libraries into the |
| GCC front end's bytecode library directory. If you need to update |
| your bytecode libraries, this is the target to use once you've built |
| them. |
| <p> |
| |
| </dl> |
| |
| It is also possible to override default values from <tt>configure</tt> by |
| declaring variables on the command line. The following are some examples: |
| |
| <dl compact> |
| <dt><tt>gmake ENABLE_OPTIMIZED=1</tt> |
| <dd> |
| Perform a Release (Optimized) build. |
| <p> |
| |
| <dt><tt>gmake ENABLE_PROFILING=1</tt> |
| <dd> |
| Perform a Profiling build. |
| <p> |
| |
| <dt><tt>gmake VERBOSE=1</tt> |
| <dd> |
| Print what <tt>gmake</tt> is doing on standard output. |
| <p> |
| </dl> |
| |
| 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. |
| |
| <!-------------------------------------------------------------------------> |
| <h3><a name="objfiles">The Location of LLVM Object Files</a></h3> |
| <!-------------------------------------------------------------------------> |
| |
| <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> |
| This is accomplished in the typical autoconf manner: |
| <ul> |
| <li>Change directory to where the LLVM object files should live: |
| <p> |
| <tt>cd <i>OBJ_ROOT</i></tt> |
| |
| <li>Run the <tt>configure</tt> script found in the LLVM source directory: |
| <p> |
| <tt><i>SRC_ROOT</i>/configure</tt> |
| </ul> |
| |
| <p> |
| The LLVM build will place files underneath <i>OBJ_ROOT</i> in directories |
| named after the build type: |
| </p> |
| |
| <dl compact> |
| <dt>Debug Builds |
| <dd> |
| <dl compact> |
| <dt>Tools |
| <dd><tt><i>OBJ_ROOT</i>/tools/Debug</tt> |
| <dt>Libraries |
| <dd><tt><i>OBJ_ROOT</i>/lib/Debug</tt> |
| </dl> |
| <p> |
| |
| <dt>Release Builds |
| <dd> |
| <dl compact> |
| <dt>Tools |
| <dd><tt><i>OBJ_ROOT</i>/tools/Release</tt> |
| <dt>Libraries |
| <dd><tt><i>OBJ_ROOT</i>/lib/Release</tt> |
| </dl> |
| <p> |
| |
| <dt>Profile Builds |
| <dd> |
| <dl compact> |
| <dt>Tools |
| <dd><tt><i>OBJ_ROOT</i>/tools/Profile</tt> |
| <dt>Libraries |
| <dd><tt><i>OBJ_ROOT</i>/lib/Profile</tt> |
| </dl> |
| </dl> |
| |
| <!--=====================================================================--> |
| <center> |
| <h2><a name="layout"><b>Program Layout</b></a></h2> |
| </center> |
| <hr> |
| <!--=====================================================================--> |
| |
| <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.cs.uiuc.edu/doxygen/">http://llvm.cs.uiuc.edu/doxygen/</a></tt>. |
| The following is a brief introduction to code layout: |
| </p> |
| |
| <!-------------------------------------------------------------------------> |
| <h3><a name="cvsdir"><tt>CVS</tt> directories</a></h3> |
| <!-------------------------------------------------------------------------> |
| |
| Every directory checked out of CVS will contain a <tt>CVS</tt> directory; |
| for the most part these can just be ignored. |
| |
| |
| <!-------------------------------------------------------------------------> |
| <h3><a name="include"><tt>llvm/include</tt></a></h3> |
| <!-------------------------------------------------------------------------> |
| |
| This directory contains public header files exported from the LLVM |
| library. The three main subdirectories of this directory are:<p> |
| |
| <ol> |
| <li><tt>llvm/include/llvm</tt> - 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... |
| |
| <li><tt>llvm/include/Support</tt> - This directory contains generic |
| support libraries that are independent of LLVM, but are used by LLVM. |
| For example, some C++ STL utilities and a Command Line option processing |
| library store their header files here. |
| |
| <li><tt>llvm/include/Config</tt> - 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. |
| </ol> |
| |
| <!-------------------------------------------------------------------------> |
| <h3><a name="lib"><tt>llvm/lib</tt></a></h3> |
| <!-------------------------------------------------------------------------> |
| |
| 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 compact> |
| <dt><tt>llvm/lib/VMCore/</tt><dd> This directory holds the core LLVM |
| source files that implement core classes like Instruction and BasicBlock. |
| |
| <dt><tt>llvm/lib/AsmParser/</tt><dd> This directory holds the source code |
| for the LLVM assembly language parser library. |
| |
| <dt><tt>llvm/lib/ByteCode/</tt><dd> This directory holds code for reading |
| and write LLVM bytecode. |
| |
| <dt><tt>llvm/lib/CWriter/</tt><dd> This directory implements the LLVM to C |
| converter. |
| |
| <dt><tt>llvm/lib/Analysis/</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... |
| |
| <dt><tt>llvm/lib/Transforms/</tt><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... |
| |
| <dt><tt>llvm/lib/Target/</tt><dd> This directory contains files that |
| describe various target architectures for code generation. For example, |
| the llvm/lib/Target/Sparc directory holds the Sparc machine |
| description.<br> |
| |
| <dt><tt>llvm/lib/CodeGen/</tt><dd> This directory contains the major parts |
| of the code generator: Instruction Selector, Instruction Scheduling, and |
| Register Allocation. |
| |
| <dt><tt>llvm/lib/Support/</tt><dd> This directory contains the source code |
| that corresponds to the header files located in |
| <tt>llvm/include/Support/</tt>. |
| </dl> |
| |
| <!-------------------------------------------------------------------------> |
| <h3><a name="runtime"><tt>llvm/runtime</tt></a></h3> |
| <!-------------------------------------------------------------------------> |
| |
| <p> |
| This directory contains libraries which are compiled into LLVM bytecode 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> |
| |
| <!-------------------------------------------------------------------------> |
| <h3><a name="test"><tt>llvm/test</tt></a></h3> |
| <!-------------------------------------------------------------------------> |
| |
| <p>This directory contains regression tests and source code that is used to |
| test the LLVM infrastructure. |
| </p> |
| |
| <!-------------------------------------------------------------------------> |
| <h3><a name="tools"><tt>llvm/tools</tt></a></h3> |
| <!-------------------------------------------------------------------------> |
| |
| <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.</p> |
| |
| <dl compact> |
| <dt> |
| |
| <dt><tt><b>analyze</b></tt><dd> <tt>analyze</tt> is used to run a specific |
| analysis on an input LLVM bytecode file and print out the results. It is |
| primarily useful for debugging analyses, or familiarizing yourself with |
| what an analysis does.<p> |
| |
| <dt><tt><b>bugpoint</b></tt><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>.<p> |
| |
| <dt><tt><b>llvm-ar</b></tt><dd>The archiver produces an archive containing |
| the given LLVM bytecode files, optionally with an index for faster |
| lookup.<p> |
| |
| <dt><tt><b>llvm-as</b></tt><dd>The assembler transforms the human readable |
| LLVM assembly to LLVM bytecode.<p> |
| |
| <dt><tt><b>llvm-dis</b></tt><dd>The disassembler transforms the LLVM |
| bytecode to human readable LLVM assembly. Additionally, it can convert |
| LLVM bytecode to C, which is enabled with the <tt>-c</tt> option.<p> |
| |
| <dt><tt><b>llvm-link</b></tt><dd> <tt>llvm-link</tt>, not surprisingly, |
| links multiple LLVM modules into a single program.<p> |
| |
| <dt><tt><b>lli</b></tt><dd> <tt>lli</tt> is the LLVM interpreter, which |
| can directly execute LLVM bytecode (although very slowly...). In addition |
| to a simple interpreter, <tt>lli</tt> also has a tracing mode (entered by |
| specifying <tt>-trace</tt> on the command line). Finally, for |
| architectures that support it (currently only x86 and Sparc), 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.<p> |
| |
| <dt><tt><b>llc</b></tt><dd> <tt>llc</tt> is the LLVM backend compiler, |
| which translates LLVM bytecode to a SPARC or x86 assembly file.<p> |
| |
| <dt><tt><b>llvmgcc</b></tt><dd> <tt>llvmgcc</tt> is a GCC-based C frontend |
| that has been retargeted to emit LLVM code as the 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. The source code for the |
| <tt>llvmgcc</tt> tool is currently not included in the LLVM CVS tree |
| because it is quite large and not very interesting.<p> |
| |
| <ol> |
| <dt><tt><b>gccas</b></tt><dd> This tool is invoked by the |
| <tt>llvmgcc</tt> frontend as the "assembler" part of the compiler. This |
| tool actually assembles LLVM assembly to LLVM bytecode, |
| performs a variety of optimizations, and outputs LLVM bytecode. Thus |
| when you invoke <tt>llvmgcc -c x.c -o x.o</tt>, you are causing |
| <tt>gccas</tt> to be run, which writes the <tt>x.o</tt> file (which is |
| an LLVM bytecode file that can be disassembled or manipulated just like |
| any other bytecode file). The command line interface to <tt>gccas</tt> |
| is designed to be as close as possible to the <b>system</b> |
| `<tt>as</tt>' utility so that the gcc frontend itself did not have to be |
| modified to interface to a "weird" assembler.<p> |
| |
| <dt><tt><b>gccld</b></tt><dd> <tt>gccld</tt> links together several LLVM |
| bytecode files into one bytecode file and does some optimization. It is |
| the linker invoked by the GCC frontend when multiple .o files need to be |
| linked together. Like <tt>gccas</tt>, the command line interface of |
| <tt>gccld</tt> is designed to match the system linker, to aid |
| interfacing with the GCC frontend.<p> |
| </ol> |
| |
| <dt><tt><b>opt</b></tt><dd> <tt>opt</tt> reads LLVM bytecode, applies a |
| series of LLVM to LLVM transformations (which are specified on the command |
| line), and then outputs the resultant bytecode. The '<tt>opt --help</tt>' |
| command is a good way to get a list of the program transformations |
| available in LLVM.<p> |
| |
| </dl> |
| |
| <!-------------------------------------------------------------------------> |
| <h3><a name="utils"><tt>llvm/utils</tt></a></h3> |
| <!-------------------------------------------------------------------------> |
| |
| 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. |
| |
| <dl compact> |
| <td><tt><b>Burg/</b></tt><dd> <tt>Burg</tt> is an instruction selector |
| generator -- it builds trees on which it then performs pattern-matching to |
| select instructions according to the patterns the user has specified. Burg |
| is currently used in the Sparc V9 backend.<p> |
| |
| <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>.<p> |
| |
| <dt><tt><b>cvsupdate</b></tt><dd> <tt>cvsupdate</tt> is a script that will |
| update your CVS tree, but produce a much cleaner and more organized output |
| than simply running <tt>`cvs -z3 up -dP'</tt> will. For example, it will group |
| together all the new and updated files and modified files in separate |
| sections, so you can see at a glance what has changed. If you are at the |
| top of your LLVM CVS tree, running <tt>utils/cvsupdate</tt> is the |
| preferred way of updating the tree.<p> |
| |
| <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.<p> |
| |
| <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.<p> |
| |
| <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.<p> |
| |
| <dt><tt><b>NightlyTest.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.cs.uiuc.edu/">LLVM homepage</a>.<p> |
| |
| <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.<p> |
| |
| <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.<p> |
| |
| </dl> |
| |
| <!--=====================================================================--> |
| <h2> |
| <center><a name="tutorial">An Example Using the LLVM Tool Chain</center> |
| </h2> |
| <hr> |
| <!--=====================================================================--> |
| |
| <ol> |
| <li>First, create a simple C file, name it 'hello.c': |
| <pre> |
| #include <stdio.h> |
| int main() { |
| printf("hello world\n"); |
| return 0; |
| } |
| </pre> |
| |
| <li>Next, compile the C file into a LLVM bytecode file:<p> |
| |
| <tt>% llvmgcc hello.c -o hello</tt><p> |
| |
| This will create two result files: <tt>hello</tt> and |
| <tt>hello.bc</tt>. The <tt>hello.bc</tt> is the LLVM bytecode that |
| corresponds the the compiled program and the library facilities that it |
| required. <tt>hello</tt> is a simple shell script that runs the bytecode |
| file with <tt>lli</tt>, making the result directly executable.<p> |
| |
| <li>Run the program. To make sure the program ran, execute one of the |
| following commands:<p> |
| |
| <tt>% ./hello</tt><p> |
| |
| or<p> |
| |
| <tt>% lli hello.bc</tt><p> |
| |
| <li>Use the <tt>llvm-dis</tt> utility to take a look at the LLVM assembly |
| code:<p> |
| |
| <tt>% llvm-dis < hello.bc | less</tt><p> |
| |
| <li>Compile the program to native Sparc assembly using the code |
| generator (assuming you are currently on a Sparc system):<p> |
| |
| <tt>% llc hello.bc -o hello.s</tt><p> |
| |
| <li>Assemble the native sparc assemble file into a program:<p> |
| |
| <tt>% /opt/SUNWspro/bin/cc -xarch=v9 hello.s -o hello.sparc</tt><p> |
| |
| <li>Execute the native sparc program:<p> |
| |
| <tt>% ./hello.sparc</tt><p> |
| |
| </ol> |
| |
| |
| <!--=====================================================================--> |
| <h2> |
| <center><a name="problems">Common Problems</a></center> |
| </h2> |
| <hr> |
| <!--=====================================================================--> |
| |
| 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. |
| |
| <!--=====================================================================--> |
| <h2><center><a name="links">Links</a></center></h2> |
| <hr> |
| <!--=====================================================================--> |
| |
| <p>This document is just an <b>introduction</b> to 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.cs.uiuc.edu/">LLVM homepage</a></li> |
| <li><a href="http://llvm.cs.uiuc.edu/doxygen/">LLVM doxygen tree</a></li> |
| <li><a href="http://llvm.cs.uiuc.edu/docs/Projects.html">Starting a Project that Uses LLVM</a></li> |
| </ul> |
| |
| <hr> |
| |
| If you have any questions or run into any snags (or you have any |
| additions...), please send an email to |
| <a href="mailto:[email protected]">Chris Lattner</a>.</p> |
| |
| <!-- Created: Mon Jul 1 02:29:02 CDT 2002 --> |
| <!-- hhmts start --> |
| Last modified: Mon Aug 11 13:52:22 CDT 2003 |
| <!-- hhmts end --> |
| </body> |
| </html> |
