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1046 lines
42 KiB
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1046 lines
42 KiB
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<html>
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<head>
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<title>Getting Started with LLVM System</title>
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</head>
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<body bgcolor=white>
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<center><h1>Getting Started with the LLVM System<br><font size=3>By: <a
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href="mailto:gshi1@uiuc.edu">Guochun Shi</a>,
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<a href="mailto:sabre@nondot.org">Chris Lattner</a>,
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<a href="mailto:criswell@uiuc.edu">John Criswell</a>,
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<a href="http://misha.brukman.net">Misha Brukman</a>, and
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<a href="http://www.cs.uiuc.edu/~vadve">Vikram Adve</a>
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</font></h1></center>
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<!--=====================================================================-->
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<h2><a name="Contents">Contents</a></h2>
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<!--=====================================================================-->
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<ul>
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<li><a href="#overview">Overview</a>
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<ol>
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<li><a href="#requirements">Requirements</a>
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<ol>
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<li><a href="#hardware">Hardware</a>
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<li><a href="#software">Software</a>
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</ol>
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</ol>
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<li><a href="#quickstart">Getting Started Quickly (A Summary)</a>
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<li><a href="#starting">Getting Started with LLVM</a>
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<ol>
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<li><a href="#terminology">Terminology and Notation</tt></a>
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<li><a href="#environment">Setting Up Your Environment</a>
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<li><a href="#unpack">Unpacking the LLVM Archives</a>
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<li><a href="#checkout">Checkout LLVM from CVS</a>
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<li><a href="#installcf">Install the GCC Front End</a>
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<li><a href="#config">Local LLVM Configuration</tt></a>
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<li><a href="#compile">Compiling the LLVM Suite Source Code</a>
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<li><a href="#objfiles">The Location of LLVM Object Files</tt></a>
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</ol>
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<li><a href="#layout">Program layout</a>
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<ol>
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<li><a href="#cvsdir"><tt>CVS</tt> directories</a>
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<li><a href="#include"><tt>llvm/include</tt></a>
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<li><a href="#lib"><tt>llvm/lib</tt></a>
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<li><a href="#runtime"><tt>llvm/runtime</tt></a>
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<li><a href="#test"><tt>llvm/test</tt></a>
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<li><a href="#tools"><tt>llvm/tools</tt></a>
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<li><a href="#utils"><tt>llvm/utils</tt></a>
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</ol>
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<li><a href="#tutorial">An Example Using the LLVM Tool Chain</a>
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<li><a href="#problems">Common Problems</a>
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<li><a href="#links">Links</a>
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</ul>
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<!--=====================================================================-->
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<center>
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<h2><a name="overview"><b>Overview</b></a></h2>
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</center>
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<hr>
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<!--=====================================================================-->
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Welcome to LLVM! In order to get started, you first need to know some
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basic information.
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<p>
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First, LLVM comes in two pieces. The first piece is the LLVM suite. This
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contains all of the tools, libraries, and header files needed to use the
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low level virtual machine. It also contains a test suite that can be used
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to test the LLVM tools and the GCC front end.
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<p>
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The second piece is the GCC front end. This component provides a version
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of GCC that compiles C and C++ code into LLVM bytecode. Currently, the
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GCC front end is a modified version of GCC 3.4 (we track the GCC 3.4
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development). Once compiled into LLVM bytecode, a program can be
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manipulated with the LLVM tools from the LLVM suite.
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<!--=====================================================================-->
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<h3><a name="requirements"><b>Requirements</b></a></h3>
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<!--=====================================================================-->
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Before you begin to use the LLVM system, review the requirements given
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below. This may save you some trouble by knowing ahead of time what
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hardware and software you will need.
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<!--=====================================================================-->
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<h4><a name="hardware"><b>Hardware</b></a></h4>
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<!--=====================================================================-->
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LLVM is known to work on the following platforms:
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<ul>
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<li> Linux on x86 (Pentium and above)
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<ul>
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<li> Approximately 760 MB of Free Disk Space
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<ul>
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<li>Source code: 30 MB
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<li>Object code: 670 MB
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<li>GCC front end: 60 MB
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</ul>
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</ul>
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<p>
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<li> Solaris on SparcV9 (Ultrasparc)
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<ul>
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<li> Approximately 1.24 GB of Free Disk Space
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<ul>
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<li>Source code: 30 MB
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<li>Object code: 1000 MB
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<li>GCC front end: 210 MB
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</ul>
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</ul>
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</ul>
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LLVM <i>may</i> compile on other platforms. The LLVM utilities should work
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on other platforms, so it should be possible to generate and produce LLVM
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bytecode on unsupported platforms (although bytecode generated on one
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platform may not work on another platform). However, the code generators
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and Just-In-Time (JIT) compilers only generate SparcV9 or x86 machine code.
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</p>
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<!--=====================================================================-->
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<h4><a name="software"><b>Software</b></a></h4>
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<!--=====================================================================-->
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<p>
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Unpacking the distribution requires the following tools:
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<dl compact>
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<dt>
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<A href="http://www.gnu.org/software/gzip/gzip.html">GNU Zip (gzip)</A>
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<dt><A href="http://www.gnu.org/software/tar/tar.html">GNU Tar</A>
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<dd>
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These tools are needed to uncompress and unarchive the software.
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Regular Solaris <tt>tar</tt> may work for unpacking the TAR archive but
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is untested.
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</dl>
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Compiling LLVM requires that you have several different software packages
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installed:
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<dl compact>
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<dt> <A href="http://gcc.gnu.org">GCC</A>
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<dd>
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The GNU Compiler Collection must be installed with C and C++ language
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support. GCC 3.2.x works, and GCC 3.x is generally supported.
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<p>
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Note that we currently do not support any other C++ compiler.
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</p>
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<dt> <A href="http://savannah.gnu.org/projects/make">GNU Make</A>
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<dd>
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The LLVM build system relies upon GNU Make extensions. Therefore, you
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will need GNU Make (sometimes known as gmake) to build LLVM.
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<p>
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<dt> <A href="http://www.gnu.org/software/flex">Flex</A>
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and
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<A href="http://www.gnu.org/software/bison/bison.html">Bison</A>
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<dd>
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The LLVM source code is built using flex and bison. You will not be
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able to configure and compile LLVM without them.
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<p>
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<dt> <A href="http://savannah.gnu.org/projects/m4">GNU M4</A>
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<dd>
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If you are installing Bison on your machine for the first time, you
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will need GNU M4 (version 1.4 or higher).
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</dl>
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<p>
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There are some additional tools that you may want to have when working with
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LLVM:
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</p>
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<ul>
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<li><A href="http://www.gnu.org/software/autoconf">GNU Autoconf</A>
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<li><A href="http://savannah.gnu.org/projects/m4">GNU M4</A>
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<p>
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If you want to make changes to the configure scripts, you will need
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GNU autoconf (2.53 or higher), and consequently, GNU M4 (version 1.4
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or higher).
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</p>
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<li><A href="http://www.codesourcery.com/qm/qmtest">QMTest</A>
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<li><A href="http://www.python.org">Python</A>
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<p>
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In order to run the tests in the LLVM test suite, you will need QMTest and
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a version of the Python interpreter that works with QMTest.
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</ul>
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<p>The remainder of this guide is meant to get you up and running with
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LLVM and to give you some basic information about the LLVM environment.
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The <a href"#quickstart">next section</a> gives a short summary for those
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who are already familiar with the system and want to get started as quickly
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as possible. A <a href="#starting">complete guide to installation</a> is
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provided in the subsequent section.
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<p>The later sections of this guide describe the <a
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href="#layout">general layout</a> of the the LLVM source-tree, a <a
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href="#tutorial">simple example</a> using the LLVM tool chain, and <a
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href="#links">links</a> to find more information about LLVM or to get
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help via e-mail.
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<!--=====================================================================-->
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<center>
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<h2><a name="quickstart"><b>Getting Started Quickly (A Summary)</b></a></h2>
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</center>
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<hr>
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<!--=====================================================================-->
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Here's the short story for getting up and running quickly with LLVM:
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<ol>
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<li>Install the GCC front end:
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<ol>
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<li><tt>cd <i>where-you-want-the-C-front-end-to-live</i></tt>
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<li><tt>gunzip --stdout cfrontend.<i>platform</i>.tar.gz | tar -xvf
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-</tt>
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</ol>
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<p>
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<li>Get the Source Code
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<ul>
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<li>With the distributed files:
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<ol>
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<li><tt>cd <i>where-you-want-llvm-to-live</i></tt>
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<li><tt>gunzip --stdout llvm.tar.gz | tar -xvf -</tt>
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<li><tt>cd llvm</tt>
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</ol>
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<p>
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<li>With anonymous CVS access:
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<ol>
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<li>Find the path to the CVS repository containing LLVM (we'll
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call this <i>CVSROOTDIR</i>).
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<li><tt>cd <i>where-you-want-llvm-to-live</i></tt>
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<li><tt>cvs -d <i>CVSROOTDIR</i> checkout llvm</tt>
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<li><tt>cd llvm</tt>
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</ol>
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</ul>
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</ul>
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<p>
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<li>Configure the LLVM Build Environment
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<ol>
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<li>Change directory to where you want to store the LLVM object
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files and run <tt>configure</tt> to configure the Makefiles and
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header files for the default platform.
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Useful options include:
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<ul>
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<li><tt>--with-llvmgccdir=<i>directory</i></tt>
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<br>
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Specify where the LLVM GCC frontend is installed.
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<p>
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<li><tt>--enable-spec2000=<i>directory</i></tt>
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<br>
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Enable the SPEC2000 benchmarks for testing. The SPEC2000
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benchmarks should be available in <tt><i>directory</i></tt>.
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</ul>
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</ol>
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<p>
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<li>Build the LLVM Suite
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<ol>
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<li>Set your LLVM_LIB_SEARCH_PATH environment variable.
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<li><tt>gmake -k |& tee gnumake.out
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# this is csh or tcsh syntax</tt>
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</ol>
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<p>
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</ol>
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<p>See <a href="#environment">Setting Up Your Environment</a> on tips to
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simplify working with the LLVM front-end and compiled tools. See the
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next section for other useful details in working with LLVM,
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or go straight to <a href="#layout">Program Layout</a> to learn about the
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layout of the source code tree.
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<!--=====================================================================-->
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<center>
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<h2><a name="starting"><b>Getting Started with LLVM</b></a></h2>
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</center>
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<hr>
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<!--=====================================================================-->
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<!------------------------------------------------------------------------->
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<h3><a name="terminology">Terminology and Notation</a></h3>
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<!------------------------------------------------------------------------->
|
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<p>Throughout this manual, the following names are used to denote paths
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specific to the local system and working environment. <i>These are not
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environment variables you need to set but just strings used in the rest
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of this document below</i>. In any of the examples below, simply replace
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each of these names with the appropriate pathname on your local system.
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All these paths are absolute:</p>
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<dl compact>
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<dt>CVSROOTDIR
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<dd>
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This is the path for the CVS repository containing the LLVM source
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code. Ask the person responsible for your local LLVM installation to
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give you this path.
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<p>
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<dt>SRC_ROOT
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<dd>
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This is the top level directory of the LLVM source tree.
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<p>
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<dt>OBJ_ROOT
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<dd>
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This is the top level directory of the LLVM object tree (i.e. the
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tree where object files and compiled programs will be placed. It
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can be the same as SRC_ROOT).
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<p>
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<dt>LLVMGCCDIR
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<dd>
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This is the where the LLVM GCC Front End is installed.
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<p>
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For the pre-built GCC front end binaries, the LLVMGCCDIR is
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<tt>cfrontend/<i>platform</i>/llvm-gcc</tt>.
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</dl>
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<!------------------------------------------------------------------------->
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<h3><a name="environment">Setting Up Your Environment</a></h3>
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<!------------------------------------------------------------------------->
|
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<p>
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In order to compile and use LLVM, you will need to set some environment
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variables. There are also some shell aliases which you may find useful.
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You can set these on the command line, or better yet, set them in your
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<tt>.cshrc</tt> or <tt>.profile</tt>.
|
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<dl compact>
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<dt><tt>LLVM_LIB_SEARCH_PATH</tt>=<tt><i>LLVMGCCDIR</i>/llvm-gcc/bytecode-libs</tt>
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<dd>
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This environment variable helps the LLVM GCC front end find bytecode
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libraries that it will need for compilation.
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<p>
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<dt>alias llvmgcc <i>LLVMGCCDIR</i><tt>/llvm-gcc/bin/gcc</tt>
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<dt>alias llvmg++ <i>LLVMGCCDIR</i><tt>/llvm-gcc/bin/g++</tt>
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<dd>
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This alias allows you to use the LLVM C and C++ front ends without putting
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them in your <tt>PATH</tt> or typing in their complete pathnames.
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</dl>
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<!------------------------------------------------------------------------->
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<h3><a name="unpack">Unpacking the LLVM Archives</a></h3>
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<!------------------------------------------------------------------------->
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<p>
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If you have the LLVM distribution, you will need to unpack it before you
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can begin to compile it. LLVM is distributed as a set of three files. Each
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file is a TAR archive that is compressed with the gzip program.
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</p>
|
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<p> The three files are as follows:
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<dl compact>
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<dt>llvm.tar.gz
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<dd>This is the source code to the LLVM suite.
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<p>
|
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<dt>cfrontend.sparc.tar.gz
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<dd>This is the binary release of the GCC front end for Solaris/Sparc.
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<p>
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<dt>cfrontend.x86.tar.gz
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<dd>This is the binary release of the GCC front end for Linux/x86.
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</dl>
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<!------------------------------------------------------------------------->
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<h3><a name="checkout">Checkout LLVM from CVS</a></h3>
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<!------------------------------------------------------------------------->
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<p>If you have access to our CVS repository, you can get a fresh copy of
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the entire source code. All you need to do is check it out from CVS as
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follows:
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<ul>
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<li><tt>cd <i>where-you-want-llvm-to-live</i></tt>
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<li><tt>cvs -d <i>CVSROOTDIR</i> checkout llvm</tt></p>
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</ul>
|
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|
<p>This will create an '<tt>llvm</tt>' directory in the current
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directory and fully populate it with the LLVM source code, Makefiles,
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test directories, and local copies of documentation files.</p>
|
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|
|
<p>
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|
Note that the GCC front end is not included in the CVS repository. You
|
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should have downloaded the binary distribution for your platform.
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</p>
|
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<!------------------------------------------------------------------------->
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<h3><a name="installcf">Install the GCC Front End</a></h3>
|
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<!------------------------------------------------------------------------->
|
|
|
|
<p>
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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
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its location must be specified when the LLVM suite is configured.
|
|
</p>
|
|
|
|
<p>
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|
To install the GCC front end, do the following:
|
|
<ol>
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<li><tt>cd <i>where-you-want-the-front-end-to-live</i></tt>
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<li><tt>gunzip --stdout cfrontend.<i>platform</i>.tar.gz | tar -xvf
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-</tt>
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</ol>
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<!------------------------------------------------------------------------->
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<h3><a name="config">Local LLVM Configuration</a></h3>
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<!------------------------------------------------------------------------->
|
|
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<p>Once checked out from the CVS repository, the LLVM suite source code
|
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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
|
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the Makefiles needed to build LLVM.
|
|
|
|
<p>
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|
The following environment variables are used by the <tt>configure</tt>
|
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script to configure the build system:
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|
</p>
|
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|
|
<table border=1>
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|
<tr>
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<th>Variable</th>
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<th>
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|
Purpose
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</th>
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</tr>
|
|
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<tr>
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|
<td>CC</td>
|
|
<td>
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|
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>
|
|
|
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<tr>
|
|
<td>CXX</td>
|
|
<td>
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|
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>
|
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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 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:sabre@nondot.org">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>
|