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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html> <html>
<head> <head>
<title>Getting Started with LLVM System</title> <title>Getting Started with LLVM System</title>
</head> </head>
<body bgcolor="white">
<body bgcolor=white>
<center> <center><h1>Getting Started with the LLVM System<br><font size=3>By: <a
<h1>Getting Started with the LLVM System<br> href="mailto:gshi1@uiuc.edu">Guochun Shi</a>,
<font size="3">By: <a href="mailto:gshi1@uiuc.edu">Guochun Shi</a>, <a <a href="mailto:sabre@nondot.org">Chris Lattner</a> and
href="mailto:sabre@nondot.org">Chris Lattner</a> and <a <a href="http://www.cs.uiuc.edu/~vadve">Vikram Adve</a>
href="http://www.cs.uiuc.edu/%7Evadve">Vikram Adve</a> </font></h1> </font></h1></center>
</center>
<!--=====================================================================--> <!--=====================================================================-->
<h2><a name="Contents">Contents</a></h2>
<h2><a name="Contents">Contents</a></h2> <!--=====================================================================-->
<!--=====================================================================-->
<ul>
<ul> <li><a href="#overview">Overview</a>
<li><a href="#overview">Overview</a> </li> <li><a href="#starting">Getting started with LLVM</a>
<li><a href="#starting">Getting started with LLVM</a> <ol>
<li><a href="#quickstart">Getting started quickly (a summary)</a>
<li><a href="#checkout">Checkout LLVM from CVS</a>
<li><a href="#terminology">Terminology and Notation</tt></a>
<li><a href="#objfiles">The location for object files</tt></a>
<li><a href="#config">Local Configuration Options</tt></a>
<li><a href="#environment">Setting up your environment</a>
<li><a href="#compile">Compiling the source code</a>
</ol>
<li><a href="#layout">Program layout</a>
<ol>
<li><a href="#cvsdir">CVS directories</a>
<li><a href="#dd"><tt>Depend</tt>, <tt>Debug</tt>, &amp;
<tt>Release</tt> directories</a></li>
<li><a href="#include"><tt>llvm/include</tt></a>
<li><a href="#lib"><tt>llvm/lib</tt></a>
<li><a href="#test"><tt>llvm/test</tt></a>
<li><a href="#tools"><tt>llvm/tools</tt></a>
</ol>
<li><a href="#tutorial">An example using the LLVM tool chain</a>
<li><a href="#links">Links</a>
</ul>
<!--=====================================================================-->
<center>
<h2><a name="overview"><b>Overview</b></a></h2>
</center>
<!--=====================================================================-->
<p>The <a href"starting">next section</a> of this guide is meant to get
you up and running with LLVM and to give you some basic information about
the LLVM environment. The <a href"#quickstart">first subsection</a> gives
a short summary for those who are already familiar with the system and
want to get started as quickly as possible.
<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</b></a></h2>
</center>
<!--=====================================================================-->
<!--=====================================================================-->
<h3><a name="quickstart"><b>Getting Started Quickly (A Summary)</b></a></h3>
<!--=====================================================================-->
Here's the short story for getting up and running quickly with LLVM:
<ol> <ol>
<li><a href="#quickstart">Getting started quickly (a summary)</a> <li>Find the path to the CVS repository containing LLVM (we'll call this <i>CVSROOTDIR</i>).
</li> <li><tt>cd <i>where-you-want-llvm-to-live</i></tt>
<li><a href="#checkout">Checkout LLVM from CVS</a> </li> <li><tt>cvs -d <i>CVSROOTDIR</i> checkout llvm</tt>
<li><a href="#terminology">Terminology and Notation</a> </li> <li><tt>cd llvm</tt>
<li><a href="#objfiles">The location for object files</a> </li> <li>Edit <tt>Makefile.config</tt> to set local paths. This includes
<li><a href="#config">Local Configuration Options</a> </li> setting the install location of the C frontend and the various paths
<li><a href="#environment">Setting up your environment</a> to the C and C++ compilers used to build LLVM itself.
</li> <li>Set your LLVM_LIB_SEARCH_PATH environment variable.
<li><a href="#compile">Compiling the source code</a> </li> <li><tt>gmake -k |& tee gnumake.out
&nbsp;&nbsp;&nbsp;# this is csh or tcsh syntax</tt>
</ol> </ol>
</li>
<li><a href="#layout">Program layout</a> <p>See <a href="#environment">Setting up your environment</a> on tips to
<ol> simplify working with the LLVM front-end and compiled tools. See the
<li><a href="#cvsdir">CVS directories</a> </li> other sub-sections below for other useful details in working with LLVM,
<li><a href="#dd"><tt>Depend</tt>, <tt>Debug</tt>, &amp; or go straight to <a href="#layout">Program Layout</a> to learn about the
<tt>Release</tt> directories</a></li> layout of the source code tree.
<li><a href="#include"><tt>llvm/include</tt></a> </li>
<li><a href="#lib"><tt>llvm/lib</tt></a> </li> <!------------------------------------------------------------------------->
<li><a href="#test"><tt>llvm/test</tt></a> </li> <h3><a name="terminology">Terminology and Notation</a></h3>
<li><a href="#tools"><tt>llvm/tools</tt></a> </li> <!------------------------------------------------------------------------->
</ol>
</li> <p>Throughout this manual, the following names are used to denote paths
<li><a href="#tutorial">An example using the LLVM tool chain</a> specific to the local system and working environment. <i>These are not
</li> environment variables you need to set, but just strings used in the rest
<li><a href="#links">Links</a> </li> of this document below.</i>. In any of the examples below, simply replace
</ul> each of these names with the appropriate pathname on your local system.
<!--=====================================================================-->
<center>
<h2><a name="overview"><b>Overview</b></a></h2>
</center>
<!--=====================================================================-->
<p>The <a href="" starting="">next section</a> of this guide is meant to
get you up and running with LLVM, and to give you some basic information
about the LLVM environment. The <a href="" #quickstart="">first subsection</a>
gives a short summary for those who are already familiar with the system
and want to get started as quickly as possible. </p>
<p>The later sections of this guide describe the <a href="" #layout="">general
layout</a> of 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>
<center>
<h2><a name="starting"><b>Getting Started</b></a></h2>
</center>
<!--=====================================================================-->
<!--=====================================================================-->
<h3><a name="quickstart"><b>Getting Started Quickly (A Summary)</b></a></h3>
<!--=====================================================================-->
Here's the short story for getting up and running quickly with LLVM:
<ol>
<li>Find the path to the CVS repository containing LLVM (we'll call
this <i>CVSROOTDIR</i>). </li>
<li><tt>cd <i>where-you-want-llvm-to-live</i></tt> </li>
<li><tt>cvs -d <i>CVSROOTDIR</i> checkout llvm</tt> </li>
<li><tt>cd llvm</tt> </li>
<li>Edit <tt>Makefile.config</tt> to set local paths. This includes
setting the install location of the C frontend and the various paths
to the C and C++ compilers used to build LLVM itself. </li>
<li>Set your LLVM_LIB_SEARCH_PATH environment variable. </li>
<li><tt>gmake -k |&amp; tee gnumake.out &nbsp;&nbsp;&nbsp;# this is
csh or tcsh syntax</tt> </li>
</ol>
<p>See <a href="#environment">Setting up your environment</a> on tips to
simplify working with the LLVM front-end and compiled tools. See the
other sub-sections below for other useful details in working with LLVM,
or go straight to <a href="#layout">Program Layout</a> to learn about
the layout of the source code tree. <!------------------------------------------------------------------------->
</p>
<h3><a name="terminology">Terminology and Notation</a></h3>
<!------------------------------------------------------------------------->
<p>Through 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> All these paths are absolute:</p>
<ul>
<ul> </ul>
</ul> <!------------------------------------------------------------------------->
<!-------------------------------------------------------------------------> <h3><a name="checkout">Checkout LLVM from CVS</a></h3>
<!------------------------------------------------------------------------->
<h3><a name="checkout">Checkout LLVM from CVS</a></h3>
<!-------------------------------------------------------------------------> <p>Before checking out the source code, you will need to know the path to
the CVS repository containing LLVM source code (we'll call this
<p>Before checking out the source code, you will need to know the path to <i>CVSROOTDIR</i> below). Ask the person responsible for your local LLVM
the CVS repository containing LLVM source code (we'll call this <i>CVSROOTDIR</i> installation to give you this path.
below). Ask the person responsible for your local LLVM installation
to give you this path. </p> <p>To get a fresh copy of the entire source code, all you
<p>To get a fresh copy of the entire source code, all you need to do need to do is check it out from CVS as follows:
is check it out from CVS as follows: </p> <ul>
<ul> <li><tt>cd <i>where-you-want-llvm-to-live</i></tt>
<li><tt>cd <i>where-you-want-llvm-to-live</i></tt> </li> <li><tt>cvs -d <i>CVSROOTDIR</i> checkout llvm</tt></p>
<li><tt>cvs -d <i>CVSROOTDIR</i> checkout llvm</tt> </ul>
<p></p>
</li> <p>This will create an '<tt>llvm</tt>' directory in the current
</ul> directory and fully populate it with the LLVM source code, Makefiles,
test directories, and local copies of documentation files.</p>
<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> <h3><a name="config">Local Configuration Options</a></h3>
<!-------------------------------------------------------------------------> <!------------------------------------------------------------------------->
<h3><a name="config">Local Configuration Options</a></h3> <p>The file <tt>llvm/Makefile.config</tt>
<!-------------------------------------------------------------------------> defines the following path variables
which are specific to a particular installation of LLVM.
<p>The file <tt>llvm/Makefile.config</tt> defines the following path These need to be modified only once after checking out a copy
variables which are specific to a particular installation of LLVM. of LLVM (if the default values do not already match your system):
These should need to be modified only once after checking out a copy
of LLVM (if the default values do not already match your system): <ul>
</p> <p><li><i>CXX</i> = Path to C++ compiler to use.
<ul> <p><li><i>OBJ_ROOT</i> = Path to the llvm directory where
object files should be placed.
<p></p> (See the Section on <a href=#objfiles>
<li><i>CXX</i> = Path to C++ compiler to use. The location for LLVM object files</a>
<p></p> for more information.)
</li> <p><li><i>LLVMGCCDIR</i> = Path to the location of the LLVM front-end
<li><i>OBJ_ROOT</i> = Path to the llvm directory where object files binaries and associated libraries.
should be placed. (See the Section on <a href="#objfiles"> The <p><li><i>PURIFY</i> = Path to the purify program.
location for LLVM object files</a> for more information.) </ul>
<p></p>
</li> In addition to settings in this file, you must set a
<li><i>LLVMGCCDIR</i> = Path to the location of the LLVM front-end <tt>LLVM_LIB_SEARCH_PATH</tt> environment variable in your startup scripts.
binaries and associated libraries. This environment variable is used to locate "system" libraries like
<p></p> "<tt>-lc</tt>" and "<tt>-lm</tt>" when linking. This variable should be set
</li> to the absolute path for the bytecode-libs subdirectory of the C front-end
<li><i>PURIFY</i> = Path to the purify program. </li> install. For example, one might use
</ul> <tt>/home/vadve/lattner/local/x86/llvm-gcc/bytecode-libs</tt> for the X86
In addition to settings in this file, you must set a <tt>LLVM_LIB_SEARCH_PATH</tt> version of the C front-end on our research machines.<p>
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 <h3><a name="objfiles">The location for LLVM object files</a></h3>
bytecode-libs subdirectory of the C front-end install. For example, <!------------------------------------------------------------------------->
<tt>/home/vadve/lattner/local/x86/llvm-gcc/bytecode-libs</tt> is used
for the X86 version of the C front-end on our research machines. <p>The LLVM make system sends most output files generated during the build
<p> <!-------------------------------------------------------------------------> into the directory defined by the variable OBJ_ROOT in
</p> <tt>llvm/Makefile.config</tt>. This can be either just your normal LLVM
<h3><a name="objfiles">The location for LLVM object files</a></h3> source tree or some other directory writable by you. You may wish to put
<!-------------------------------------------------------------------------> object files on a different filesystem either to keep them from being backed
up or to speed up local builds.
<p>The LLVM make system sends most output files generated during the build
into the directory defined by the variable OBJ_ROOT in <tt>llvm/Makefile.config</tt>. <p>If you do not wish to use a different location for object files (i.e.
This can be either just your normal LLVM source tree or some other directory you are building into the source tree directly), just set this variable to
writable by you. You may wish to put object files on a different filesystem ".".<p>
either to keep them from being backed up or to speed up local builds.
</p> <!------------------------------------------------------------------------->
<p>If you do not wish to use a different location for object files (i.e. <h3><a name="environment">Setting up your environment</a></h3>
building into the source tree directly), just set this variable to ".".</p> <!------------------------------------------------------------------------->
<p> <!------------------------------------------------------------------------->
</p> <i>NOTE: This step is optional but will set up your environment so you
<h3><a name="environment">Setting up your environment</a></h3> can use the compiled LLVM tools with as little hassle as
<!-------------------------------------------------------------------------> possible.</i>)
<i>NOTE: This step is optional but will set up your environment so you
can use the compiled LLVM tools with as little hassle as possible.</i>) <p>Add the following lines to your <tt>.cshrc</tt> (or the corresponding
lines to your <tt>.profile</tt> if you use a bourne shell derivative).
<p>Add the following lines to your <tt>.cshrc</tt> (or the corresponding
lines to your <tt>.profile</tt> if you use a bourne shell derivative). <pre>
</p> # Make the C front end easy to use...
<pre> # Make the C front end easy to use...<br> alias llvmgcc <i>LLVMGCCDIR</i><tt>/bin/llvm-gcc</tt> alias llvmgcc <i>LLVMGCCDIR</i><tt>/bin/llvm-gcc</tt>
# Make the LLVM tools easy to use... # Make the LLVM tools easy to use...
setenv PATH <i>OBJ_ROOT</i>/llvm/tools/Debug:${PATH}<br> </pre> setenv PATH <i>OBJ_ROOT</i>/llvm/tools/Debug:${PATH}
The <tt>llvmgcc</tt> alias is useful because the C compiler is not </pre>
included in the CVS tree you just checked out. The <tt>llvmgcc</tt> alias is useful because the C compiler is not
<p>The other <a href="#tools">LLVM tools</a> are part of the LLVM source included in the CVS tree you just checked out.
base and are built when compiling LLVM. They will be built into the
<tt><i>OBJ_ROOT</i>/tools/Debug</tt> directory.</p>
<!------------------------------------------------------------------------->
<h3><a name="compile">Compiling the source code</a></h3> <p>The other <a href="#tools">LLVM tools</a> are part of the LLVM
<!-------------------------------------------------------------------------> source base and built when compiling LLVM. They will be built into the
<tt><i>OBJ_ROOT</i>/tools/Debug</tt> directory.</p>
<p>Every directory in the LLVM source tree includes a <tt>Makefile</tt> to
build it and any subdirectories that it contains. These makefiles require <!------------------------------------------------------------------------->
GNU Make (<tt>gmake)</tt> instead of <tt>make</tt> to build them, but <h3><a name="compile">Compiling the source code</a></h3>
can otherwise be used freely. To build the entire LLVM system, just <!------------------------------------------------------------------------->
enter the top level <tt>llvm</tt> directory and type <tt>gmake</tt>.
A few minutes later you will hopefully have a freshly compiled toolchain <p>Every directory in the LLVM source tree includes a <tt>Makefile</tt> to
waiting for you in <tt><i>OBJ_ROOT</i></tt><tt>/llvm/tools/Debug</tt>. build it and any subdirectories that it contains. These makefiles require
If you want to look at the libraries that were compiled, look in <tt><i>OBJ_ROOT</i></tt><tt>/llvm/lib/Debug</tt>.</p> that you use GNU Make (aka <tt>gmake</tt>) instead of <tt>make</tt> to
If you get an error about the <tt>/localhome</tt> directory, chances build them, but can
are good that something has been misconfigured. &nbsp;Follow the instructions otherwise be used freely. To build the entire LLVM system, just enter the
in the section about <a href="#environment">Setting Up Your Environment.</a> top level <tt>llvm</tt> directory and type <tt>gmake</tt>. A few minutes
<!--=====================================================================--> later you will hopefully have a freshly compiled toolchain waiting for you
in <tt><i>OBJ_ROOT</i>/llvm/tools/Debug</tt>. If you want to look at the
<center> libraries that were compiled, look in
<h2><a name="layout"><b>Program Layout</b></a></h2> <tt><i>OBJ_ROOT</i>/llvm/lib/Debug</tt>.</p>
</center>
<!--=====================================================================--> If you get an error about a <tt>/localhome</tt> directory, follow the
instructions in the section about <a href="#environment">Setting Up Your
<p>One useful source of infomation about the LLVM sourcebase is the LLVM Environment.</a>
<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>
<!-------------------------------------------------------------------------> <!--=====================================================================-->
<center>
<h3><a name="cvsdir"><tt>CVS</tt> directories</a></h3> <h2><a name="layout"><b>Program Layout</b></a></h2>
<!-------------------------------------------------------------------------> </center>
Every directory checked out of CVS will contain a <tt>CVS</tt> directory; <!--=====================================================================-->
for the most part, these can just be ignored. <!------------------------------------------------------------------------->
<p>One useful source of infomation about the LLVM sourcebase is the LLVM <a
<h3><a name="ddr"><tt>Depend</tt>, <tt>Debug</tt>, &amp; <tt>Release</tt> 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="ddr"><tt>Depend</tt>, <tt>Debug</tt>, &amp; <tt>Release</tt>
directories</a></h3> directories</a></h3>
<!-------------------------------------------------------------------------> <!------------------------------------------------------------------------->
If you are building with the "<tt>OBJ_ROOT=.</tt>" option enabled in
the <tt>Makefile.config</tt> file, most source directories will contain If you are building with the "<tt>OBJ_ROOT=.</tt>" option enabled in the
two directories, <tt>Depend</tt> and <tt>Debug</tt>. The <tt>Depend</tt> <tt>Makefile.config</tt> file, most source directories will contain two
directory contains automatically generated dependance files which are directories, <tt>Depend</tt> and <tt>Debug</tt>. The <tt>Depend</tt>
used during compilation to make sure that source files get rebuilt if directory contains automatically generated dependance files which are used
a header file they use is modified. The <tt>Debug</tt> directory holds during compilation to make sure that source files get rebuilt if a header
the object files, library files, and executables that are used for building file they use is modified. The <tt>Debug</tt> directory holds the object
a debug enabled build. The <tt>Release</tt> directory is created to files, library files, and executables that are used for building a debug
hold the same files when the <tt>ENABLE_OPTIMIZED=1</tt> flag is passed enabled build. The <tt>Release</tt> directory is created to hold the same
to <tt>gmake</tt>, causing an optimized built to be performed. files when the <tt>ENABLE_OPTIMIZED=1</tt> flag is passed to <tt>gmake</tt>,
<p> <!-------------------------------------------------------------------------> causing an optimized built to be performed.<p>
</p>
<h3><a name="include"><tt>llvm/include</tt></a></h3>
<!-------------------------------------------------------------------------> <!------------------------------------------------------------------------->
This directory contains public header files exported from the LLVM <h3><a name="include"><tt>llvm/include</tt></a></h3>
library. The two main subdirectories of this directory are: <!------------------------------------------------------------------------->
<p> </p>
<ol> This directory contains public header files exported from the LLVM
<li><tt>llvm/include/llvm</tt> - This directory contains all of the library. The two main subdirectories of this directory are:<p>
LLVM specific header files. This directory also has subdirectories
for different portions of LLVM: <tt>Analysis</tt>, <tt>CodeGen</tt>,
<tt>Reoptimizer</tt>, <tt>Target</tt>, <tt>Transforms</tt>, etc...
</li>
<li><tt>llvm/include/Support</tt> - This directory contains generic
support libraries that are independant of LLVM, but are used by LLVM.
For example, some C++ STL utilities and a Command Line option processing
library. </li>
</ol>
<!------------------------------------------------------------------------->
<h3><a name="lib"><tt>llvm/lib</tt></a></h3>
<!------------------------------------------------------------------------->
This directory contains most source files of 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> </p>
<dl compact="compact">
<dt><tt>llvm/lib/VMCore/</tt></dt>
<dd> This directory holds the core LLVM source files that implement
core classes like Instruction and BasicBlock. </dd>
<dt><tt>llvm/lib/AsmParser/</tt></dt>
<dd> This directory holds the source code for the LLVM assembly language
parser library. </dd>
<dt><tt>llvm/lib/ByteCode/</tt></dt>
<dd> This directory holds code for reading and write LLVM bytecode.
</dd>
<dt><tt>llvm/lib/CWriter/</tt></dt>
<dd> This directory implements the LLVM to C converter. </dd>
<dt><tt>llvm/lib/Analysis/</tt></dt>
<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>llvm/lib/Transforms/</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 Invarient Code
Motion, Dead Global Elimination, Pool Allocation, and many others...
</dd>
<dt><tt>llvm/lib/Target/</tt></dt>
<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>
</dd>
<dt><tt>llvm/lib/CodeGen/</tt></dt>
<dd> This directory contains the major parts of the code generator:
Instruction Selector, Instruction Scheduling, and Register Allocation.
</dd>
<dt><tt>llvm/lib/Reoptimizer/</tt></dt>
<dd> This directory holds code related to the runtime reoptimizer
framework that is currently under development. </dd>
<dt><tt>llvm/lib/Support/</tt></dt>
<dd> This directory contains the source code that corresponds to
the header files located in <tt>llvm/include/Support/</tt>. </dd>
</dl>
<!------------------------------------------------------------------------->
<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="compact">
<dt><tt><b>as</b></tt></dt>
<dd>The assembler transforms the human readable LLVM assembly to
LLVM bytecode.
<p> </p>
</dd>
<dt><tt><b>dis</b></tt></dt>
<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> </p>
</dd>
<dt><tt><b>lli</b></tt></dt>
<dd> <tt>lli</tt> is the LLVM interpreter, which can directly execute
LLVM bytecode (although very slowly...). In addition to a simple intepreter,
<tt>lli</tt> is also has debugger and tracing modes (entered by
specifying <tt>-debug</tt> or <tt>-trace</tt> on the command line,
respectively).
<p> </p>
</dd>
<dt><tt><b>llc</b></tt></dt>
<dd> <tt>llc</tt> is the LLVM backend compiler, which translates
LLVM bytecode to a SPARC assembly file.
<p> </p>
</dd>
<dt><tt><b>llvmgcc</b></tt></dt>
<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> </p>
<ol> <ol>
<dt><tt><b>gccas</b></tt></dt> <li><tt>llvm/include/llvm</tt> - This directory contains all of the LLVM
<dd> This tool is invoked by the <tt>llvmgcc</tt> frontend specific header files. This directory also has subdirectories for
as the "assembler" part of the compiler. This tool actually assembles different portions of LLVM: <tt>Analysis</tt>, <tt>CodeGen</tt>,
LLVM assembly to LLVM bytecode, performs a variety of optimizations, <tt>Reoptimizer</tt>, <tt>Target</tt>, <tt>Transforms</tt>, etc...
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 <li><tt>llvm/include/Support</tt> - This directory contains generic
the <tt>x.o</tt> file (which is an LLVM bytecode file that can be support libraries that are independant of LLVM, but are used by LLVM.
disassembled or manipulated just like any other bytecode file). For example, header files for some C++ STL utilities and a Command Line
The command line interface to <tt>gccas</tt> is designed to be as option processing library are located here.
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 "wierd" assembler.
<p> </p>
</dd>
<dt><tt><b>gccld</b></tt></dt>
<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> </p>
</dd>
</ol> </ol>
</dd>
<dt><tt><b>opt</b></tt></dt> <!------------------------------------------------------------------------->
<dd> <tt>opt</tt> reads LLVM bytecode, applies a series of LLVM to <h3><a name="lib"><tt>llvm/lib</tt></a></h3>
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 This directory contains most source files of LLVM system. In LLVM, almost
in LLVM. all code exists in libraries, making it very easy to share code among the
<p> </p> different <a href="#tools">tools</a>.<p>
</dd>
<dt><tt><b>analyze</b></tt></dt> <dl compact>
<dd> <tt>analyze</tt> is used to run a specific analysis on an input <dt><tt>llvm/lib/VMCore/</tt><dd> This directory holds the core LLVM
LLVM bytecode file and print out the results. It is primarily useful source files that implement core classes like Instruction and BasicBlock.
for debugging analyses, or familiarizing yourself with what an analysis
does. <dt><tt>llvm/lib/AsmParser/</tt><dd> This directory holds the source code
<p> </p> for the LLVM assembly language parser library.
</dd>
</dl> <dt><tt>llvm/lib/ByteCode/</tt><dd> This directory holds code for reading
<!--=====================================================================--> and write LLVM bytecode.
<h2><a name="tutorial">An example using the LLVM tool chain</a></h2> <dt><tt>llvm/lib/CWriter/</tt><dd> This directory implements the LLVM to C
<a name="tutorial"> <!--=====================================================================--> converter.
</a>
<ol> <dt><tt>llvm/lib/Analysis/</tt><dd> This directory contains a variety of
<a name="tutorial"> <li>First, create a simple C file, name it 'hello.c': different program analyses, such as Dominator Information, Call Graphs,
Induction Variables, Interval Identification, Natural Loop Identification,
<pre> #include &lt;stdio.h&gt;<br> int main() {<br> printf("hello world\n");<br> return 0;<br> }<br> </pre> etc...
</li>
<li>Next, compile the C file into a LLVM bytecode file: <dt><tt>llvm/lib/Transforms/</tt><dd> This directory contains the source
<p> <tt>% llvmgcc hello.c -o hello</tt></p> code for the LLVM to LLVM program transformations, such as Aggressive Dead
<p> This will create two result files: <tt>hello</tt> and Code Elimination, Sparse Conditional Constant Propagation, Inlining, Loop
<tt>hello.bc</tt>. The <tt>hello.bc</tt> is the LLVM bytecode that Invarient Code Motion, Dead Global Elimination, Pool Allocation, and many
corresponds the the compiled program and the library facilities that it others...
required. <tt>hello</tt> is a simple shell script that runs the bytecode
file with <tt>lli</tt>, making the result directly executable.</p> <dt><tt>llvm/lib/Target/</tt><dd> This directory contains files that
<p> </p> describe various target architectures for code generation. For example,
</li> the llvm/lib/Target/Sparc directory holds the Sparc machine
<li>Run the program. To make sure the program ran, execute one of the description.<br>
following commands:
<p> <tt>% ./hello</tt></p> <dt><tt>llvm/lib/CodeGen/</tt><dd> This directory contains the major parts
<p> or</p> of the code generator: Instruction Selector, Instruction Scheduling, and
<p> <tt>% lli hello.bc</tt></p> Register Allocation.
<p> </p>
</li> <dt><tt>llvm/lib/Reoptimizer/</tt><dd> This directory holds code related
<li>Use the <tt>dis</tt> utility to take a look at the LLVM assembly to the runtime reoptimizer framework that is currently under development.
code:
<p> <tt>% dis &lt; hello.bc | less</tt></p> <dt><tt>llvm/lib/Support/</tt><dd> This directory contains the source code
<p> </p> that corresponds to the header files located in
</li> <tt>llvm/include/Support/</tt>.
<li>Compile the program to native Sparc assembly using the code generator: </dl>
<p> <tt>% llc hello.bc -o hello.s</tt></p>
<p> </p> <!------------------------------------------------------------------------->
</li> <h3><a name="test"><tt>llvm/test</tt></a></h3>
<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>
<p> </p> <p>This directory contains regression tests and source code that is used to
</li> test the LLVM infrastructure...</p>
<li>Execute the native sparc program:
<p> <tt>% ./hello.sparc</tt></p> <!------------------------------------------------------------------------->
<p> </p> <h3><a name="tools"><tt>llvm/tools</tt></a></h3>
</li> <!------------------------------------------------------------------------->
</a>
</ol> <p>The <b>tools</b> directory contains the executables built out of the
<a name="tutorial"> <!--=====================================================================--> libraries above, which form the main part of the user interface. You can
</a> always get help for a tool by typing <tt>tool_name --help</tt>. The
<h2><a name="links">Links</a></h2> following is a brief introduction to the most important tools.</p>
<!--=====================================================================-->
<dl compact>
<p>This document is just an <b>introduction</b> to how to use LLVM to do <dt><tt><b>as</b></tt><dd>The assembler transforms the human readable
some simple things... there are many more interesting and complicated LLVM assembly to LLVM bytecode.<p>
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 <dt><tt><b>dis</b></tt><dd>The disassembler transforms the LLVM bytecode
about LLVM, check out:</p> 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>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 intepreter, <tt>lli</tt> is also has debugger and tracing
modes (entered by specifying <tt>-debug</tt> or <tt>-trace</tt> on the
command line, respectively).<p>
<dt><tt><b>llc</b></tt><dd> <tt>llc</tt> is the LLVM backend compiler,
which translates LLVM bytecode to a SPARC 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 "wierd"
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>
<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>
</dl>
<!--=====================================================================-->
<h2><a name="tutorial">An example using the LLVM tool chain</h2>
<!--=====================================================================-->
<ol>
<li>First, create a simple C file, name it 'hello.c':
<pre>
#include &lt;stdio.h&gt;
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>
<ul> <tt>% ./hello</tt><p>
<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> or<p>
</ul> <tt>% lli hello.bc</tt><p>
<hr> If you have any questions or run into any snags (or you have any <li>Use the <tt>dis</tt> utility to take a look at the LLVM assembly
additions...), please send an email to <a code:<p>
href="mailto:sabre@nondot.org">Chris Lattner</a>.
<p></p> <tt>% dis < hello.bc | less</tt><p>
<!-- Created: Mon Jul 1 02:29:02 CDT 2002 --> <!-- hhmts start -->
Last modified: Tue Jun 3 22:06:43 CDT 2003 <!-- hhmts end --> <br> <li>Compile the program to native Sparc assembly using the code
</body> generator:<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><a name="links">Links</a></h2>
<!--=====================================================================-->
<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>
</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:sabre@nondot.org">Chris Lattner</a>.</p>
<!-- Created: Mon Jul 1 02:29:02 CDT 2002 -->
<!-- hhmts start -->
Last modified: Tue Jun 3 22:06:43 CDT 2003
<!-- hhmts end -->
</body>
</html> </html>