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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<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:gshi1@uiuc.edu">Guochun Shi</a>, <a
href="mailto:sabre@nondot.org">Chris Lattner</a> and <a
href="http://www.cs.uiuc.edu/%7Evadve">Vikram Adve</a> </font></h1>
</center>
<!--=====================================================================-->
<h2><a name="Contents">Contents</a></h2>
<!--=====================================================================-->
<ul>
<li><a href="#overview">Overview</a> </li>
<li><a href="#starting">Getting started with LLVM</a>
<ol>
<li><a href="#quickstart">Getting started quickly (a summary)</a>
</li>
<li><a href="#checkout">Checkout LLVM from CVS</a> </li>
<li><a href="#terminology">Terminology and Notation</a> </li>
<li><a href="#objfiles">The location for object files</a> </li>
<li><a href="#config">Local Configuration Options</a> </li>
<li><a href="#environment">Setting up your environment</a>
</li>
<li><a href="#compile">Compiling the source code</a> </li>
</ol>
</li>
<li><a href="#layout">Program layout</a>
<ol>
<li><a href="#cvsdir">CVS directories</a> </li>
<li><a href="#dd"><tt>Depend</tt>, <tt>Debug</tt>, &
<tt>Release</tt> directories</a></li>
<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>
<li><a href="#tools"><tt>llvm/tools</tt></a> </li>
</ol>
</li>
<li><a href="#tutorial">An example using the LLVM tool chain</a>
</li>
<li><a href="#links">Links</a> </li>
</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>
<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 |& tee gnumake.out # 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>
<ul>
</ul>
<!------------------------------------------------------------------------->
<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 <i>CVSROOTDIR</i>
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 need to do
is check it out from CVS as follows: </p>
<ul>
<li><tt>cd <i>where-you-want-llvm-to-live</i></tt> </li>
<li><tt>cvs -d <i>CVSROOTDIR</i> checkout llvm</tt>
<p></p>
</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>
<!------------------------------------------------------------------------->
<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.
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):
</p>
<ul>
<p></p>
<li><i>CXX</i> = Path to C++ compiler to use.
<p></p>
</li>
<li><i>OBJ_ROOT</i> = Path to the llvm directory where object files
should be placed. (See the Section on <a href="#objfiles"> The
location for LLVM object files</a> for more information.)
<p></p>
</li>
<li><i>LLVMGCCDIR</i> = Path to the location of the LLVM front-end
binaries and associated libraries.
<p></p>
</li>
<li><i>PURIFY</i> = Path to the purify program. </li>
</ul>
In addition to settings in this file, you must set a <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 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> <!------------------------------------------------------------------------->
</p>
<h3><a name="objfiles">The location for LLVM object files</a></h3>
<!------------------------------------------------------------------------->
<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>.
This can be either just your normal LLVM 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>
<p>If you do not wish to use a different location for object files (i.e.
building into the source tree directly), just set this variable to ".".</p>
<p> <!------------------------------------------------------------------------->
</p>
<h3><a name="environment">Setting up your environment</a></h3>
<!------------------------------------------------------------------------->
<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>
<pre> # Make the C front end easy to use...<br> alias llvmgcc <i>LLVMGCCDIR</i><tt>/bin/llvm-gcc</tt>
# Make the LLVM tools easy to use...
setenv PATH <i>OBJ_ROOT</i>/llvm/tools/Debug:${PATH}<br> </pre>
The <tt>llvmgcc</tt> alias is useful because the C compiler is not
included in the CVS tree you just checked out.
<p>The other <a href="#tools">LLVM tools</a> are part of the LLVM source
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>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
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
waiting for you in <tt><i>OBJ_ROOT</i></tt><tt>/llvm/tools/Debug</tt>.
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>
If you get an error about the <tt>/localhome</tt> directory, chances
are good that something has been misconfigured. Follow the instructions
in the section about <a href="#environment">Setting Up Your Environment.</a>
<!--=====================================================================-->
<center>
<h2><a name="layout"><b>Program Layout</b></a></h2>
</center>
<!--=====================================================================-->
<p>One useful source of infomation about the LLVM sourcebase 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="ddr"><tt>Depend</tt>, <tt>Debug</tt>, & <tt>Release</tt>
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
two directories, <tt>Depend</tt> and <tt>Debug</tt>. The <tt>Depend</tt>
directory contains automatically generated dependance files which are
used during compilation to make sure that source files get rebuilt if
a header file they use is modified. The <tt>Debug</tt> directory holds
the object files, library files, and executables that are used for building
a debug enabled build. The <tt>Release</tt> directory is created to
hold the same files when the <tt>ENABLE_OPTIMIZED=1</tt> flag is passed
to <tt>gmake</tt>, 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
library. The two main subdirectories of this directory are:
<p> </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>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>
</
|
