<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="mailto:sabre@nondot.org">Chris Lattner</a>,
+ <a href="mailto:criswell@uiuc.edu">John Criswell</a>, and
<a href="http://www.cs.uiuc.edu/~vadve">Vikram Adve</a>
</font></h1></center>
<ul>
<li><a href="#overview">Overview</a>
+ <ol>
+ <li><a href="#requirements">Requirements</a>
+ <ol>
+ <li><a href="#hardware">Hardware</a>
+ <li><a href="#software">Software</a>
+ </ol>
+ </ol>
<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="#quickstart">Getting Started Quickly (A Summary)</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>
+ <li><a href="#environment">Setting Up Your Environment</a>
+ <li><a href="#unpack">Unpacking the LLVM Archives</a>
+ <li><a href="#checkout">Checkout LLVM from CVS</a>
+ <li><a href="#installcf">Install the C Front End</a>
+ <li><a href="#config">Local LLVM Configuration</tt></a>
+ <li><a href="#compile">Compiling the LLVM Suite Source Code</a>
+ <li><a href="#objfiles">The Location of LLVM Object Files</tt></a>
</ol>
<li><a href="#layout">Program layout</a>
<ol>
- <li><a href="#cvsdir">CVS directories</a>
- <li><a href="#dd"><tt>Depend</tt>, <tt>Debug</tt>, &
- <tt>Release</tt> directories</a></li>
+ <li><a href="#cvsdir"><tt>CVS</tt> directories</a>
<li><a href="#include"><tt>llvm/include</tt></a>
<li><a href="#lib"><tt>llvm/lib</tt></a>
<li><a href="#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="#cfront">Compiling the LLVM C Front End</a>
+ <li><a href="#tutorial">An Example Using the LLVM Tool Chain</a>
+ <li><a href="#problems">Common Problems</a>
<li><a href="#links">Links</a>
</ul>
</center>
<!--=====================================================================-->
- <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
+ Welcome to LLVM! In order to get started, you first need to know some
+ basic information.
+
+ <p>
+ First, LLVM comes in two pieces. The first piece is the LLVM suite. This
+ contains all of the tools, libraries, and header files needed to use the
+ low level virtual machine. It also contains a test suite that can be used
+ to test the LLVM tools and the C front end.
+ <p>
+ The second piece is the C front end. This component provides a version
+ of GCC that compiles C code into LLVM bytecode. Currently, the C front end
+ is a modified version of GCC 3.4 (we track the GCC 3.4 development).
+ Once compiled into LLVM bytecode, a program can be manipulated with the
+ LLVM tools from the LLVM suite.
+
+ <!--=====================================================================-->
+ <h3><a name="requirements"><b>Requirements</b></a></h3>
+ <!--=====================================================================-->
+
+ Before you begin to use the LLVM system, review the requirements given
+ below. This may save you some trouble by knowing ahead of time what
+ hardware and software you will need.
+
+ <!--=====================================================================-->
+ <h4><a name="hardware"><b>Hardware</b></a></h4>
+ <!--=====================================================================-->
+ LLVM is known to work on the following platforms:
+ <ul>
+ <li> Linux on x86
+ <ul>
+ <li> Approximately 760 MB of Free Disk Space
+ <ul>
+ <li>Source code: 30 MB
+ <li>Object code: 670 MB
+ <li>C front end: 60 MB
+ </ul>
+ </ul>
+
+ <p>
+
+ <li> Solaris on SparcV9 (Ultrasparc)
+ <ul>
+ <li> Approximately 1.24 GB of Free Disk Space
+ <ul>
+ <li>Source code: 30 MB
+ <li>Object code: 1000 MB
+ <li>C front end: 210 MB
+ </ul>
+ </ul>
+ </ul>
+
+ <p>
+ If you want to compile your own version of the C front end, you will need
+ additional disk space:
+ </p>
+
+ <ul>
+ <li>Linux on x86
+ <ul>
+ <li> Approximately 249 MB of Free Disk Space
+ <ul>
+ <li>Source code: 146 MB
+ <li>Object code: 82 MB
+ <li>Installed binaries: 21 MB
+ </ul>
+ </ul>
+
+ <p>
+
+ <li>Solaris on Sparc
+ <ul>
+ <li> Approximately 264 MB of Free Disk Space
+ <ul>
+ <li>Source code: 146 MB
+ <li>Object code: 93 MB
+ <li>Installed binaries: 25 MB
+ </ul>
+ </ul>
+ </ul>
+
+ <p>
+ LLVM <i>may</i> compile on other platforms. The LLVM utilities should work
+ on other platforms, so it should be possible to generate and produce LLVM
+ bytecode on unsupported platforms (although bytecode generated on one
+ platform may not work on another platform). However, the code generators
+ and Just-In-Time (JIT) compilers only generate SparcV9 or x86 machine code.
+ </p>
+
+ <!--=====================================================================-->
+ <h4><a name="software"><b>Software</b></a></h4>
+ <!--=====================================================================-->
+ <p>
+
+ Unpacking the distribution requires the following tools:
+ <dl compact>
+ <dt>GNU Zip (gzip)
+ <dt>GNU Tar
+ <dd>
+ These tools are needed to uncompress and unarchive the software.
+ Regular Solaris <tt>tar</tt> may work for unpacking the TAR archive but
+ is untested.
+ </dl>
+
+ Compiling LLVM requires that you have several different software packages
+ installed:
+
+ <dl compact>
+ <dt> GCC
+ <dd>
+ The GNU Compiler Collection must be installed with C and C++ language
+ support. GCC 3.2.x works, and GCC 3.x is generally supported.
+
+ <p>
+ Note that we currently do not support any other C++ compiler.
+ </p>
+
+ <dt> GNU Make
+ <dd>
+ The LLVM build system relies upon GNU Make extensions. Therefore, you
+ will need GNU Make (sometimes known as gmake) to build LLVM.
+ <p>
+
+ <dt> Flex and Bison
+ <dd>
+ The LLVM source code is built using flex and bison. You will not be
+ able to configure and compile LLVM without them.
+ <p>
+
+ <dt> GNU M4
+ <dd>
+ If you are installing Bison on your machine for the first time, you
+ will need GNU M4 (version 1.4 or higher).
+ </dl>
+
+ <p>
+ There are some additional tools that you may want to have when working with
+ LLVM:
+ </p>
+
+ <ul>
+ <li>GNU Autoconf
+ <li>GNU M4
+ <p>
+ If you want to make changes to the configure scripts, you will need
+ GNU autoconf (2.53 or higher), and consequently, GNU M4 (version 1.4
+ or higher).
+ </p>
+ </ul>
+
+
+ <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
="#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>
+ <h2><a name="starting"><b>Getting Started with LLVM</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:
- <ul>
- <li>Find the path to the CVS repository containing LLVM (we'll call this <i>CVSROOTDIR</i>).
- <li><tt>cd <i>where-you-want-llvm-to-live</i></tt>
- <li><tt>cvs -d <i>CVSROOTDIR</i> checkout llvm</tt>
- <li>Edit <tt>llvm/Makefile.config</tt> to set local paths if necessary.
- <li><tt>cd llvm</tt>
- <li><tt>gmake -k |& tee gnumake.out
- # this is csh or tcsh syntax</tt>
- </ul>
+ <ol>
+ <li>Install the C front end:
+ <ol>
+ <li><tt>cd <i>where-you-want-the-C-front-end-to-live</i></tt>
+ <li><tt>gunzip --stdout cfrontend.<i>platform</i>.tar.gz | tar -xvf
+ -</tt>
+ </ol>
+
+ <p>
+
+ <li>Get the Source Code
+ <ul>
+ <li>With the distributed files:
+ <ol>
+ <li><tt>cd <i>where-you-want-llvm-to-live</i></tt>
+ <li><tt>gunzip --stdout llvm.tar.gz | tar -xvf -</tt>
+ <li><tt>gunzip --stdout cfrontend.<i>platform</i>.tar.gz | tar -xvf -</tt>
+ <li><tt>cd llvm</tt>
+ </ol>
+
+ <p>
+
+ <li>With anonymous CVS access:
+ <ol>
+ <li>Find the path to the CVS repository containing LLVM (we'll call this <i>CVSROOTDIR</i>).
+ <li><tt>cd <i>where-you-want-llvm-to-live</i></tt>
+ <li><tt>cvs -d <i>CVSROOTDIR</i> checkout llvm</tt>
+ <li><tt>cd llvm</tt>
+ </ol>
+ </ul>
+ </ul>
+
+ <p>
+
+ <li>Configure the LLVM Build Environment
+ <ol>
+ <li>Run <tt>configure</tt> to configure the Makefiles and header
+ files for the default platform.
+ Useful options include:
+ <ul>
+ <li><tt>--with-objroot=<i>directory</i></tt>
+ <br>
+ Specify where object files should be placed during the build.
+
+ <li><tt>--with-llvmgccdir=<i>directory</i></tt>
+ <br>
+ Specify where the LLVM C frontend is going to be installed.
+ </ul>
+ </ol>
+
+ <p>
+
+ <li>Build the LLVM Suite
+ <ol>
+ <li>Set your LLVM_LIB_SEARCH_PATH environment variable.
+ <li><tt>gmake -k |& tee gnumake.out
+ # this is csh or tcsh syntax</tt>
+ </ol>
+
+ <p>
+
+ </ol>
- <p>See <a href="#environment">Setting up your environment</a> on tips to
- simplify working with the llvm front-end and compiled tools. See the
+ <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.
+ layout of the source code tree. For information on building the C front
+ end yourself, see <a href="#cfront">Compiling the LLVM C Front End</a> for
+ information.
<!------------------------------------------------------------------------->
<h3><a name="terminology">Terminology and Notation</a></h3>
<!------------------------------------------------------------------------->
- <p>Through this manual, the following names are used to denote paths
+ <p>Throughout this manual, the following names are used to denote paths
specific to the local system and working environment. <i>These are not
- environment variables you need to set, but just strings used in the rest
- of this document below.</i>. In any of the examples below, simply replace
+ 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>
+ <dl compact>
+ <dt>CVSROOTDIR
+ <dd>
+ This is the path for the CVS repository containing the LLVM source
+ code. Ask the person responsible for your local LLVM installation to
+ give you this path.
+ <p>
+
+ <dt>OBJ_ROOT
+ <dd>
+ This is the top level directory for where the LLVM suite object files
+ will be placed during the build.
+ <p>
+
+ <dt>LLVMGCCDIR
+ <dd>
+ This is the pathname to the location where the LLVM C Front End will
+ be installed. Note that the C front end does not need to be installed
+ during the LLVM suite build; you will just need to know where it will
+ go for configuring the build system and running the test suite later.
+ <p>
+ For the pre-built C front end binaries, the LLVMGCCDIR is
+ <tt>cfrontend/<i>platform</i>/llvm-gcc</tt>.
+
+ <dt>GCCSRC
+ <dd>
+ This is the pathname of the directory where the LLVM C front end source
+ code can be found.
+ <p>
+
+ <dt>GCCOBJ
+ <dd>
+ This is the pathname of the directory where the LLVM C front end object
+ code will be placed during the build. It can be safely removed once
+ the build is complete.
+ </dl>
<!------------------------------------------------------------------------->
- <h3><a name="checkout">Checkout LLVM from CVS</a></h3>
+ <h3><a name="environment">Setting Up Your Environment</a></h3>
+ <!------------------------------------------------------------------------->
+
+ <p>
+ In order to compile and use LLVM, you will need to set some environment
+ variables. There are also some shell aliases which you may find useful.
+ You can set these on the command line, or better yet, set them in your
+ <tt>.cshrc</tt> or <tt>.profile</tt>.
+
+ <dl compact>
+ <dt><tt>LLVM_LIB_SEARCH_PATH</tt>=<tt><i>LLVMGCCDIR</i>/llvm-gcc/bytecode-libs</tt>
+ <dd>
+ This environment variable helps the LLVM C front end find bytecode
+ libraries that it will need for compilation.
+ <p>
+
+ <dt>alias llvmgcc <i>LLVMGCCDIR</i><tt>/bin/llvm-gcc</tt>
+ <dd>
+ This alias allows you to use the LLVM C front end without putting it in
+ your <tt>PATH</tt> or typing in its complete pathname.
+ </dl>
+
+ <!------------------------------------------------------------------------->
+ <h3><a name="unpack">Unpacking the LLVM Archives</a></h3>
<!------------------------------------------------------------------------->
- <p>Before checking out the source code, you will need to know the path to
- 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>
+ If you have the LLVM distribution, you will need to unpack it before you
+ can begin to compile it. LLVM is distributed as a set of four files. Each
+ file is a TAR archive that is compressed with the gzip program.
+ </p>
+
+ <p> The four files are as follows:
+ <dl compact>
+ <dt>llvm.tar.gz
+ <dd>This is the source code to the LLVM suite.
+ <p>
+
+ <dt>cfrontend.sparc.tar.gz
+ <dd>This is the binary release of the C front end for Solaris/Sparc.
+ <p>
+
+ <dt>cfrontend.x86.tar.gz
+ <dd>This is the binary release of the C front end for Linux/x86.
+ <p>
+
+ <dt>cfrontend-src.tar.gz
+ <dd>This is the source code release of the C front end.
+ <p>
+ </dl>
+
+ <!------------------------------------------------------------------------->
+ <h3><a name="checkout">Checkout LLVM from CVS</a></h3>
+ <!------------------------------------------------------------------------->
- <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>If you have access to our CVS repository, you can get a fresh copy of
+ the entire source code. All you need to do is check it out from CVS as
+ follows:
<ul>
<li><tt>cd <i>where-you-want-llvm-to-live</i></tt>
<li><tt>cvs -d <i>CVSROOTDIR</i> checkout llvm</tt></p>
directory and fully populate it with the LLVM source code, Makefiles,
test directories, and local copies of documentation files.</p>
+ <p>
+ Note that the C front end is not included in the CVS repository. You
+ should have either downloaded the source, or better yet, downloaded the
+ binary distribution for your platform.
+ </p>
+
<!------------------------------------------------------------------------->
- <h3><a name="config">Local Configuration Options</a></h3>
+ <h3><a name="installcf">Install the C Front End</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>
+ Before configuring and compiling the LLVM suite, it is best to extract the
+ LLVM C front end. While not used in building, the C front end is used by
+ the LLVM test suite, and its location must be given to the
+ <tt>configure</tt> script before the LLVM suite can be built.
+ </p>
- <ul>
- <p><li><i>LLVM_OBJ_DIR</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><li><i>LLVMGCCDIR</i> = Path to the location of the LLVM front-end
- binaries and associated libraries.
- <p><li><i>BURG</i> = Path to the burg program used for instruction
- selection.
- <p><li><i>PURIFY</i> = Path to the purify program.
- </ul>
+ <p>
+ To install the C front end, do the following:
+ <ol>
+ <li><tt>cd <i>where-you-want-the-front-end-to-live</i></tt>
+ <li><tt>gunzip --stdout cfrontend.<i>platform</i>.tar.gz | tar -xvf
+ -</tt>
+ </ol>
<!------------------------------------------------------------------------->
- <h3><a name="objfiles">The location for LLVM object files</a></h3>
+ <h3><a name="config">Local LLVM Configuration</a></h3>
<!------------------------------------------------------------------------->
- <p>The LLVM make system sends most output files generated during the build
- into the directory defined by the variable LLVM_OBJ_DIR in
- <tt>llvm/Makefile.config</tt>.
- This can be either just your normal </tt>llvm</tt> 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>Once checked out from the CVS repository, the LLVM suite source code
+ must be configured via the <tt>configure</tt> script. This script sets
+ variables in <tt>llvm/Makefile.config</tt> and
+ <tt>llvm/include/Config/config.h</tt>.
+
+ <p>
+ The following environment variables are used by the <tt>configure</tt>
+ script to configure the build system:
+ </p>
+
+ <table border=1>
+ <tr>
+ <th>Variable</th>
+ <th>
+ Purpose
+ </th>
+ </tr>
+
+ <tr>
+ <td>CC</td>
+ <td>
+ Tells <tt>configure</tt> which C compiler to use. By default,
+ <tt>configure</tt> will look for the first GCC compiler in
+ <tt>PATH</tt>. Use this variable to override
+ <tt>configure</tt>'s default behavior.
+ </td>
+ </tr>
+
+ <tr>
+ <td>CXX</td>
+ <td>
+ Tells <tt>configure</tt> which C++ compiler to use. By default,
+ <tt>configure</tt> will look for the first GCC 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-objroot=OBJ_ROOT</i>
+ <dd>
+ Path to the directory where
+ object files, libraries, and executables should be placed.
+ If this is set to <tt>.</tt>, then the object files will be placed
+ within the source code tree. If left unspecified, the default value is
+ <tt>.</tt>.
+ (See the Section on <a href=#objfiles>
+ The Location of LLVM Object Files</a>
+ for more information.)
+ <p>
+ <dt><i>--with-llvmgccdir=LLVMGCCDIR</i>
+ <dd>
+ Path to the location where the LLVM C front end binaries and
+ associated libraries will be installed.
+ <p>
+ <dt><i>--enable-optimized</i>
+ <dd>
+ Enables optimized compilation (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.
+ </dl>
- <p>If you do not wish to use a different location for object files,
- just set this variable to ".".
+ 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 C front-end
+ install, or LLVMGCCDIR/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 C front-end on our research machines.<p>
<!------------------------------------------------------------------------->
- <h3><a name="environment">Setting up your environment</a></h3>
+ <h3><a name="compile">Compiling the LLVM Suite Source Code</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>)
+ Once you have configured LLVM, you can build it. There are three types of
+ builds:
- <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).
+ <dl compact>
+ <dt>Debug Builds
+ <dd>
+ These builds are the default. They 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>. They compile the tools and libraries with GCC
+ optimizer flags on 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 setting variables on the
+ <tt>gmake</tt> command line.
+ </dl>
- <pre>
- # Make the C front end easy to use...
- alias llvmgcc <i>LLVMGCCDIR</i><tt>/bin/gcc</tt>
+ Once you have LLVM configured, you can build it by entering the top level
+ <tt>llvm</tt> directory and issuing the following command:
+ <p>
+ <tt>gmake</tt>
- # Make the LLVM tools easy to use...
- setenv PATH <i>LLVM_OBJ_DIR</i>/tools/Debug:${PATH}
- </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 LLVM <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>LLVM_OBJ_DIR</i>/tools/Debug</tt> directory.</p>
+ <p>
+ If you have multiple processors in your machine, you may wish to use some
+ of the parallel build options provided by GNU Make. For example, you could
+ use the command:
+ </p>
- <!------------------------------------------------------------------------->
- <h3><a name="compile">Compiling the source code</a></h3>
- <!------------------------------------------------------------------------->
+ <p>
+ <tt>gmake -j2</tt>
- <p>Every directory in the LLVM source tree includes a Makefile to build it,
- and any subdirectories that it contains. These makefiles require that you
- use <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>llvm/tools/Debug</tt>. If you want to look at the libraries that
- were compiled, look in <tt>llvm/lib/Debug</tt>.</p>
+ <p>
+ There are several other targets which are useful when working with the LLVM
+ source code:
- If you get an error talking about a <tt>/shared</tt> directory, follow the
- instructions in the section about <a href="#environment">Setting Up Your
- Environment.</a>
+ <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>
+ </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 source tree includes a <tt>Makefile</tt> to
+ build it and any subdirectories that it contains. Entering any directory
+ inside the LLVM source 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 sends most output files generated during the build
+ into the directory defined by the variable <i>OBJ_ROOT</i> in
+ <tt>llvm/Makefile.config</tt>, which is set by the <i>--with-objroot</i>
+ option in <tt>configure</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>
+ If <i>OBJ_ROOT</i> is specified, then the build system will create a
+ directory tree underneath it that resembles the source code's pathname
+ relative to your home directory.
+ </p>
+
+ <p>
+ For example, suppose that <i>OBJ_ROOT</i> is set to <tt>/tmp</tt> and the
+ LLVM suite source code is located in <tt>/usr/home/joe/src/llvm</tt>, where
+ <tt>/usr/home/joe</tt> is the home directory of a user named Joe. Then,
+ the object files will be placed in <tt>/tmp/src/llvm</tt>.
+ </p>
+
+ <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>/llvm/tools/Debug</tt>
+ <dt>Libraries
+ <dd><tt><i>OBJ_ROOT</i>/llvm/lib/Debug</tt>
+ </dl>
+ <p>
+
+ <dt>Release Builds
+ <dd>
+ <dl compact>
+ <dt>Tools
+ <dd><tt><i>OBJ_ROOT</i>/llvm/tools/Release</tt>
+ <dt>Libraries
+ <dd><tt><i>OBJ_ROOT</i>/llvm/lib/Release</tt>
+ </dl>
+ <p>
+
+ <dt>Profile Builds
+ <dd>
+ <dl compact>
+ <dt>Tools
+ <dd><tt><i>OBJ_ROOT</i>/llvm/tools/Profile</tt>
+ <dt>Libraries
+ <dd><tt><i>OBJ_ROOT</i>/llvm/lib/Profile</tt>
+ </dl>
+ </dl>
<!--=====================================================================-->
<center>
</center>
<!--=====================================================================-->
- <p>One useful source of info
mation about the LLVM sourcebase is the LLVM <a
+ <p>One useful source of info
rmation 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,
+ 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>BUILD_ROOT=.</tt>" option enabled in the
- <tt>Makefile.common</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>
-
-
<!------------------------------------------------------------------------->
<h3><a name="include"><tt>llvm/include</tt></a></h3>
<!------------------------------------------------------------------------->
This directory contains public header files exported from the LLVM
- library. The t
wo main subdirectories of this directory are:<p>
+ library. The t
hree 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>,
+ different portions of LLVM: <tt>Analysis</tt>, <tt>CodeGen</tt>,
<tt>Reoptimizer</tt>, <tt>Target</tt>, <tt>Transforms</tt>, etc...
<li><tt>llvm/include/Support</tt> - This directory contains generic
- support libraries that are independant of LLVM, but are used by LLVM.
+ 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.
+
+ <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 configure
+ script generates.
</ol>
<!------------------------------------------------------------------------->
<h3><a name="lib"><tt>llvm/lib</tt></a></h3>
<!------------------------------------------------------------------------->
- This directory contains most source files of LLVM system. In LLVM almost all
+ 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>
<dt><tt>llvm/lib/ByteCode/</tt><dd> This directory holds code for reading
and write LLVM bytecode.
- <dt><tt>llvm/lib/CWrite/</tt><dd> This directory implements the LLVM to C
+ <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
<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 Propogation, Inlining, Loop
+ Code Elimination, Sparse Conditional Constant Propagation, Inlining, Loop
Invarient Code Motion, Dead Global Elimination, Pool Allocation, and many
others...
<dl compact>
<dt><tt><b>as</b></tt><dd>The assembler transforms the human readable
-
llvm assembly to llvm bytecode.<p>
+
LLVM assembly to LLVM bytecode.<p>
- <dt><tt><b>dis</b></tt><dd>The disassembler transforms the llvm bytecode
- to human readable llvm assembly. Additionally it can convert LLVM
+ <dt><tt><b>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>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
+ to a simple interpreter, <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>
+ command line, respectively). 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 assembly file.<p>
+ 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
<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,
+ 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"
+ 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
+ <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
interfacing with the GCC frontend.<p>
</ol>
- <dt><tt><b>opt</b></tt><dd> <tt>opt</tt> reads llvm bytecode, applies a
+ <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
what an analysis does.<p>
</dl>
-
+
+ <!--=====================================================================-->
+ <h2><center><a name="cfront">Compiling the LLVM C Front End</center></h2>
+ <!--=====================================================================-->
+
+ <p>
+ <b>
+ This step is optional if you have the C front end binary distrubtion for
+ your platform.
+ </b>
+ </p>
+
+ Now that you have the LLVM suite built, you can build the C front end. For
+ those of you that have built GCC before, the process is very similar.
+ <p>
+ Be forewarned, though: the build system for the C front end is not as
+ polished as the rest of the LLVM code, so there will be many warnings and
+ errors that you will need to ignore for now:
+
+ <ol>
+ <li>Ensure that <tt><i>OBJ_ROOT</i>/llvm/tools/Debug</tt> is at the
+ <i>end</i> of your <tt>PATH</tt> environment variable. The front end
+ build needs to know where to find the LLVM tools, but you want to
+ ensure that these tools are not found before the system assembler and
+ linker that you normally use for compilation.
+
+ <li><tt>cd <i>GCCOBJ</i></tt>
+
+ <li>Configure the source code:
+ <ul>
+ <li>On Linux/x86, use
+ <ul>
+ <li><tt><i>GCCSRC</i>/configure --prefix=<i>LLVMGCCDIR</i>
+ --enable-languages=c</tt>
+ </ul>
+
+ <li>On Solaris/Sparc, use
+ <ul>
+ <li><tt><i>GCCSRC</i>/configure --prefix=<i>LLVMGCCDIR</i>
+ --enable-languages=c --target=sparcv9-sun-solaris2</tt>
+ </ul>
+ </ul>
+
+ <li><tt>gmake</tt>
+
+ <li>The build will eventually fail. Don't worry; chances are good that
+ everything that needed to build is built.
+
+ <li><tt>gmake -k install</tt>
+ </ol>
+
+ <p>
+ Once this is done, you should have a built front end compiler in
+ <tt><i>LLVMGCCDIR</i></tt>.
+ </p>
+
<!--=====================================================================-->
- <h2><a name="tutorial">An example using the LLVM tool chain</h2>
+ <h2>
+ <center><a name="tutorial">An Example Using the LLVM Tool Chain</center>
+ </h2>
<!--=====================================================================-->
<ol>
<tt>% dis < hello.bc | less</tt><p>
<li>Compile the program to native Sparc assembly using the code
- generator:<p>
+ generator
(assuming you are currently on a Sparc system):<p>
<tt>% llc hello.bc -o hello.s</tt><p>
<!--=====================================================================-->
- <h2><a name="links">Links</a></h2>
+ <h2>
+ <center><a name="problems">Common Problems</a></center>
+ </h2>
+ <!--=====================================================================-->
+
+ Below are common problems and their remedies:
+
+ <dl compact>
+ <dt><b>When I run configure, it finds the wrong C compiler.</b>
+ <dd>
+ The <tt>configure</tt> script attempts to locate first <tt>gcc</tt> and
+ then <tt>cc</tt>, unless it finds compiler paths set in <tt>CC</tt> and
+ <tt>CXX</tt> for the C and C++ compiler, respectively.
+
+ If <tt>configure</tt> finds the wrong compiler, either adjust your
+ <tt>PATH</tt> environment variable or set <tt>CC</tt> and <tt>CXX</tt>
+ explicitly.
+ <p>
+
+ <dt><b>I compile the code, and I get some error about /localhome</b>.
+ <dd>
+ There are several possible causes for this. The first is that you
+ didn't set a pathname properly when using <tt>configure</tt>, and it
+ defaulted to a pathname that we use on our research machines.
+ <p>
+ Another possibility is that we hardcoded a path in our Makefiles. If
+ you see this, please email the LLVM bug mailing list with the name of
+ the offending Makefile and a description of what is wrong with it.
+
+ <dt><b>The <tt>configure</tt> script finds the right C compiler, but it
+ uses the LLVM linker from a previous build. What do I do?</b>
+ <dd>
+ The <tt>configure</tt> script uses the <tt>PATH</tt> to find
+ executables, so if it's grabbing the wrong linker/assembler/etc, there
+ are two ways to fix it:
+ <ol>
+ <li>Adjust your <tt>PATH</tt> environment variable so that the
+ correct program appears first in the <tt>PATH</tt>. This may work,
+ but may not be convenient when you want them <i>first</i> in your
+ path for other work.
+ <p>
+
+ <li>Run <tt>configure</tt> with an alternative <tt>PATH</tt> that
+ is correct. In a Borne compatible shell, the syntax would be:
+ <p>
+ <tt>PATH=<the path without the bad program> ./configure ...</tt>
+ <p>
+ This is still somewhat inconvenient, but it allows
+ <tt>configure</tt> to do its work without having to adjust your
+ <tt>PATH</tt> permanently.
+ </ol>
+ </dl>
+
+ <!--=====================================================================-->
+ <h2><center><a name="links">Links</a></center></h2>
<!--=====================================================================-->
<p>This document is just an <b>introduction</b> to how to use LLVM to do
<ul>
<li><a href="http://llvm.cs.uiuc.edu/">LLVM homepage</a></li>
- <li><a href="http://tank.cs.uiuc.edu/doxygen/">LLVM doxygen tree</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:hldnbrnd@uiuc.edu">Nicholas Hildenbrandt</a> or
<a href="mailto:sabre@nondot.org">Chris Lattner</a>.</p>
<!-- Created: Mon Jul 1 02:29:02 CDT 2002 -->
<!-- hhmts start -->
-Last modified: Tue Aug 13 16:09:25 CDT 2002
+Last modified: Tue Jun 3 22:06:43 CDT 2003
<!-- hhmts end -->
</body>
</html>
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