Performed a major update for the pre-release.

Attempted to better structure and order the document.
Added more information about autoconf, the build system, and how to build LLVM.
Added directions on how to build the C front end.
Added a section on common problems and their solutions.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@7096 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
John Criswell 2003-07-03 16:01:38 +00:00
parent f2413aedb6
commit ce760f6f54

View File

@ -18,26 +18,27 @@
<ul>
<li><a href="#overview">Overview</a>
<li><a href="#starting">Getting started with LLVM</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="#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="#checkout">Checkout LLVM from CVS</a>
<li><a href="#config">Local LLVM Configuration</tt></a>
<li><a href="#compile">Compiling the LLVM Suite Source Code</a>
<li><a href="#build">Building the LLVM C Front End</a>
<li><a href="#objfiles">The location for 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>, &amp;
<tt>Release</tt> directories</a></li>
<li><a href="#include"><tt>llvm/include</tt></a>
<li><a href="#lib"><tt>llvm/lib</tt></a>
<li><a href="#test"><tt>llvm/test</tt></a>
@ -54,7 +55,111 @@
</center>
<!--=====================================================================-->
<p>The <a href"starting">next section</a> of this guide is meant to get
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 GCC front end.
<p>
The second piece is the GCC 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.
<!--=====================================================================-->
<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 700 MB of Free Disk Space
<ul>
<li>Source code: 30 MB
<li>Object code: 670 MB
</ul>
</ul>
<li> Solaris on SparcV9 (Ultrasparc)
<ul>
<li> Approximately 1.03 GB of Free Disk Space
<ul>
<li>Source code: 30 MB
<li>Object code: 1000 MB
</ul>
</ul>
</ul>
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 Compilers (JIT's) only generate SparcV9 or x86 machine
code.
<!--=====================================================================-->
<h4><a name="software"><b>Software</b></a></h4>
<!--=====================================================================-->
<p>
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
@ -72,88 +177,13 @@
</center>
<!--=====================================================================-->
<!--=====================================================================-->
<h3><a name="requirements"><b>Requirements</b></a></h3>
<!--=====================================================================-->
<!--=====================================================================-->
<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 700 MB of Free Disk Space
<ul>
<li>Source code: 30 MB
<li>Object code: 670 MB
</ul>
</ul>
<li> Solaris on Sparc
<ul>
<li> Approximately 1.03 GB of Free Disk Space
<ul>
<li>Source code: 30 MB
<li>Object code: 1000 MB
</ul>
</ul>
</ul>
LLVM may compile on other platforms. While the LLVM utilities should work,
they will only generate Sparc or x86 machine code.
<!--=====================================================================-->
<h4><a name="software"><b>Software</b></a></h4>
<!--=====================================================================-->
<p>
Compiling LLVM requires that you have several different software packages
installed:
<ul>
<li> GCC
<p>
The GNU Compiler Collection must be installed with C and C++ language
support. GCC 3.x is supported, although some effort has been made to
support GCC 2.96.
</p>
<p>
Note that we currently do not support any other C++ compiler.
</p>
<li> GNU Make
<p>
The LLVM build system relies upon GNU Make extensions. Therefore, you
will need GNU Make (sometimes known as gmake) to build LLVM.
</p>
<li> Flex and Bison
<p>
The LLVM source code is built using flex and bison. You will not be
able to configure and compile LLVM without them.
</p>
</ul>
<p>
There are some additional tools that you may want to have when working with
LLVM:
</p>
<ul>
<li> GNU Autoconf and GNU M4
<p>
If you want to make changes to the autoconf scripts which configure LLVM
for compilation, you will need GNU autoconf, and consequently, GNU M4.
LLVM was built with autoconf 2.53, so that release and any later
release should work.
</p>
</ul>
<!--=====================================================================-->
<h3><a name="quickstart"><b>Getting Started Quickly (A Summary)</b></a></h3>
<!--=====================================================================-->
Here's the short story for getting up and running quickly with LLVM:
<ol>
<li>Build the LLVM suite
<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>
@ -164,16 +194,26 @@
<ul>
<li><tt>--with-objroot=<i>directory</i></tt>
<br>
Specifiy where object files should be placed during the build.
Specify where object files should be placed during the build.
<li><tt>--with-llvmgccdir=<i>directory</i></tt>
<br>
Specifiy where the LLVM C frontend has been installed.
Specify where the LLVM C frontend is going to be installed.
</ul>
<li>Set your LLVM_LIB_SEARCH_PATH environment variable.
<li><tt>gmake -k |& tee gnumake.out
&nbsp;&nbsp;&nbsp;# this is csh or tcsh syntax</tt>
</ol>
<p>
<li>Build the LLVM C Front End
<ol>
<li>Create a directory for the object files to live.
<li><tt>cd <i>object file directory</i></tt>
<li>Run <tt><i>Pathname-to-where-the-source-code-lives</i>/configure --prefix=<i>LLVMGCCDIR</i></tt> to configure GCC.
<li><tt>make bootstrap</tt>
<li><tt>make install</tt>
</ol>
</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
@ -191,18 +231,94 @@
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>
<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="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><tt>PATH</tt>=<tt>${PATH}:<i>OBJ_ROOT</i>/llvm/tools/Debug</tt>
<dd>
Adding this directory to the end of your path will allow the
compilation of the C front end to find the LLVM tools. The LLVM tools
are needed for the C front end compile.
<p>
<dt><tt>CC</tt>=<i>Pathname to your GCC compiler</i>
<dd>
The GCC compiler that you want to use must be the first C compiler in
your <tt>PATH</tt>. Otherwise, set this variable so that
<tt>configure</tt> will use the GCC compiler that you want to use.
<p>
<dt><tt>CXX</tt>=<i>Pathname to your GCC C++ compiler</i>
<dd>
The GCC compiler that you want to use must be the first C++ compiler in
your <tt>PATH</tt>. Otherwise, set this variable so that
<tt>configure</tt> will use the GCC compiler that you want to use.
<p>
<dt><tt>CVSROOT</tt>=<i>CVSROOT</i>
<dd>
This environment variable tells CVS where to find the CVS repository.
<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="checkout">Checkout LLVM from CVS</a></h3>
<!------------------------------------------------------------------------->
<p>Before checking out the source code, you will need to know the path to
the CVS repository containing the 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>To get a fresh copy of the entire source code, all you
need to do is check it out from CVS as follows:
<ul>
@ -214,13 +330,19 @@
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="config">Local LLVM Configuration</a></h3>
<!------------------------------------------------------------------------->
<p>Once checked out from the CVS repository, options and pathnames specific
to an installation of LLVM can be set via the <tt>configure</tt> script.
This script sets variables in <tt>llvm/Makefile.config</tt> and
<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>
@ -235,96 +357,244 @@
The following options can be used to set or enable LLVM specific options:
<ul>
<p><li><i>--with-objroot=LLVM_OBJ_ROOT</i> =
<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 for LLVM object files</a>
for more information.)
<p><li><i>--with-llvmgccdir=LLVMGCCDIR</i> =
Path to the location of the LLVM front-end
binaries and associated libraries.
<p><li><i>--enable-optimized</i> =
<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).
<p><li><i>--enable-jit</i> =
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.
</ul>
on all platforms. The default is dependent on platform, so it is best
to explicitly enable it if you want it.
</dl>
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. For example, one might set <tt>LLVM_LIB_SEARCH_PATH</tt> to
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="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. 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>make</tt> command line.
</dl>
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>make</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>make -j2</tt>
<p>
There are several other targets which are useful when working with the LLVM
source code:
<dl compact>
<dt><tt>make clean</tt>
<dd>
Removes all files generated by the build. This includes object files,
generated C/C++ files, libraries, and executables.
<p>
<dt><tt>make distclean</tt>
<dd>
Removes everything that <tt>make 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>make ENABLE_OPTIMIZED=1</tt>
<dd>
Perform a Release (Optimized) build.
<p>
<dt><tt>make ENABLE_PROFILING=1</tt>
<dd>
Perform a Profiling build.
<p>
<dt><tt>make VERBOSE=1</tt>
<dd>
Print what <tt>make</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>make</tt> should rebuild
anything in or below that directory that is out of date.
<!------------------------------------------------------------------------->
<h3><a name="build">Building the LLVM C Front End</a></h3>
<!------------------------------------------------------------------------->
<b>
<p>
This step is optional if you have the C front end binary distrubtion for
your platform.
</p>
</b>
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.
<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>make bootstrap</tt>
<li>The build will eventually fail. Don't worry; chances are good that
everything that needed to build is built.
<li><tt>make install</tt>
</ol>
At this point, you should have a working copy of the LLVM C front end
installed in <i>LLVMGCCDIR</i>.
<!------------------------------------------------------------------------->
<h3><a name="objfiles">The location for LLVM object files</a></h3>
<!------------------------------------------------------------------------->
<p>The LLVM make system sends most output files generated during the build
into the directory defined by the variable OBJ_ROOT in
<tt>llvm/Makefile.config</tt>. This can be either just your normal LLVM
<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 you wish to place output files into a separate directory, use the
<tt>--with-objroot=<i>directory</i></tt> option of <tt>configure</tt> to
set the top level directory of where the object files will go. Otherwise,
leave this option unspecified, and <tt>configure</tt> will place files
within the LLVM source tree.
<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>
<!------------------------------------------------------------------------->
<h3><a name="environment">Setting up your environment</a></h3>
<!------------------------------------------------------------------------->
<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>
<i>NOTE: This step is optional but will set up your environment so you
can use the compiled LLVM tools with as little hassle as
possible.</i>)
<p>
The LLVM build will place files underneath <i>OBJ_ROOT</i> in directories
named after the build type:
</p>
<p>Add the following lines to your <tt>.cshrc</tt> (or the corresponding
lines to your <tt>.profile</tt> if you use a bourne shell derivative).
<pre>
# Make the C front end easy to use...
alias llvmgcc <i>LLVMGCCDIR</i><tt>/bin/llvm-gcc</tt>
# Make the LLVM tools easy to use...
setenv PATH <i>OBJ_ROOT</i>/llvm/tools/Debug:${PATH}
</pre>
The <tt>llvmgcc</tt> alias is useful because the C compiler is not
included in the CVS tree you just checked out.
<p>The other <a href="#tools">LLVM tools</a> are part of the LLVM
source base and built when compiling LLVM. They will be built into the
<tt><i>OBJ_ROOT</i>/tools/Debug</tt> directory.</p>
<!------------------------------------------------------------------------->
<h3><a name="compile">Compiling the source code</a></h3>
<!------------------------------------------------------------------------->
<p>Every directory in the LLVM source tree includes a <tt>Makefile</tt> to
build it and any subdirectories that it contains. These makefiles require
that you use GNU Make (sometimes called <tt>gmake</tt>) instead of
<tt>make</tt> to
build them, but can
otherwise be used freely. To build the entire LLVM system, just enter the
top level <tt>llvm</tt> directory and type <tt>gmake</tt>. A few minutes
later you will hopefully have a freshly compiled toolchain waiting for you
in <tt><i>OBJ_ROOT</i>/llvm/tools/Debug</tt>. If you want to look at the
libraries that
were compiled, look in <tt><i>OBJ_ROOT</i>/llvm/lib/Debug</tt>.</p>
If you get an error about a <tt>/localhome</tt> directory, follow the
instructions in the section about <a href="#environment">Setting Up Your
Environment.</a>
<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>
@ -332,7 +602,7 @@
</center>
<!--=====================================================================-->
<p>One useful source of infomation about the LLVM sourcebase is the LLVM <a
<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>
@ -346,25 +616,6 @@
for the most part these can just be ignored.
<!------------------------------------------------------------------------->
<h3><a name="ddr"><tt>Depend</tt>, <tt>Debug</tt>, &amp; <tt>Release</tt>
directories</a></h3>
<!------------------------------------------------------------------------->
If you are building with the "<tt>OBJ_ROOT=.</tt>" option enabled in the
<tt>Makefile.config</tt> file (i.e. you did not specify
<tt>--with-objroot</tt> when you ran <tt>configure</tt>), 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 build to be performed.<p>
<!------------------------------------------------------------------------->
<h3><a name="include"><tt>llvm/include</tt></a></h3>
<!------------------------------------------------------------------------->
@ -379,7 +630,7 @@
<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.
@ -466,7 +717,7 @@
<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>
@ -491,7 +742,7 @@
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"
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
@ -570,6 +821,58 @@
</ol>
<!--=====================================================================-->
<h2><a name="help">Common Problems</a></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><a name="links">Links</a></h2>
<!--=====================================================================-->
@ -583,6 +886,7 @@
<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>