</ol></li>
<li><a href="#tutorial">An Example Using the LLVM Tool Chain</a>
+ <ol>
+ <li><a href="#tutorial4">Example with llvm-gcc4</a></li>
+ <li><a href="#tutorial3">Example with llvm-gcc3</a></li>
+ </ol>
<li><a href="#problems">Common Problems</a>
<li><a href="#links">Links</a>
</ul>
<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 contains an assembler, disassembler, bytecode
-analyzer, and bytecode optimizer. It also contains a test suite that can be
+analyzer and bytecode optimizer. It also contains a test suite that can be
used to test the LLVM tools and the GCC front end.</p>
<p>The second piece is the GCC front end. This component provides a version of
<p>LLVM is known to work on the following platforms:</p>
-<table cellpadding="3">
+<table cellpadding="3" summary="Known LLVM platforms">
<tr>
<th>OS</th>
<th>Arch</th>
<p>LLVM has partial support for the following platforms:</p>
-<table>
+<table summary="LLVM partial platform support">
<tr>
<th>OS</th>
<th>Arch</th>
<li><a name="pf_3">No native code generation</a></li>
<li><a name="pf_4">Build is not complete: one or more tools don't link</a></li>
<li><a name="pf_5">The GCC-based C/C++ frontend does not build</a></li>
-<li><a name="pf_6">The port is done using the MSYS shell.
+<li><a name="pf_6">The port is done using the MSYS shell.</a>
<a href="http://www.mingw.org/MinGWiki/">Download</a> and install
bison (excl. M4.exe) and flex in that order. Build binutils-2.15 from source,
-if necessary. Bison & flex can be also grabbed from GNUWin32 sf.net project</li>
+if necessary. Bison & flex can be also grabbed from GNUWin32 sf.net
+project.</li>
<li><a name="pf_7">Native code generation exists but is not complete.</a></li>
-<li><a name="pf_8">Binutils up to post-2.17 has bug in bfd/cofflink.c
+<li><a name="pf_8">Binutils</a> up to post-2.17 has bug in bfd/cofflink.c
preventing LLVM from building correctly. Several workarounds have been
introduced into LLVM build system, but the bug can occur anytime in the
- future. It's highly recommended to rebuild your current binutils with the
+ future. We highly recommend that you rebuild your current binutils with the
patch from <a href="http://sourceware.org/bugzilla/show_bug.cgi?id=2659">
- Binutils bugzilla</a>, if it's wasn't already applied. </a></li>
+ Binutils bugzilla</a>, if it wasn't already applied.</li>
</ol>
</div>
is the usual name for the software package that LLVM depends on. The Version
column provides "known to work" versions of the package. The Notes column
describes how LLVM uses the package and provides other details.</p>
- <table>
+ <table summary="Packages required to compile LLVM">
<tr><th>Package</th><th>Version</th><th>Notes</th></tr>
<tr>
<p><b>Notes:</b></p>
<div class="doc_notes">
<ol>
- <li><a name="sf3">Only the C and C++ languages are needed so there's no
+ <li><a name="sf1">Only the C and C++ languages are needed so there's no
need to build the other languages for LLVM's purposes.</a> See
<a href="#brokengcc">below</a> for specific version info.</li>
<li><a name="sf2">You only need CVS if you intend to build from the
<p><b>Apple Xcode 2.3</b>: GCC crashes when compiling LLVM at -O3 (which is the
default with ENABLE_OPTIMIZED=1. To work around this, build with
"ENABLE_OPTIMIZED=1 OPTIMIZE_OPTION=-O2".</p>
+<p><b>GCC 4.1.1</b>: GCC fails to build LLVM with template concept check errors
+ compiling some files. At the time of this writing, GCC mainline (4.2)
+ did not share the problem.</p>
+<p><b>GNU ld 2.16.X</b>. Some 2.16.X versions of the ld linker will produce very
+long warning messages complaining that some ".gnu.linkonce.t.*" symbol was
+defined in a discarded section. You can safely ignore these messages as they are
+erroneous and the linkage is correct. These messages disappear using ld
+2.17.</p>
</div>
<dt>SRC_ROOT
<dd>
This is the top level directory of the LLVM source tree.
- <p>
+ <br><br>
<dt>OBJ_ROOT
<dd>
This is the top level directory of the LLVM object tree (i.e. the
tree where object files and compiled programs will be placed. It
can be the same as SRC_ROOT).
- <p>
+ <br><br>
<dt>LLVMGCCDIR
<dd>
<dd>Binary release of the llvm-gcc4 front end for MacOS X/X86.<br/></dd>
</dl>
-<p>It is also possible to download the sources of the llvm-gcc4 front end from
-a read-only subversion mirror at svn://anonsvn.opensource.apple.com/svn/llvm.
-</p>
+<p>It is also possible to download the sources of the llvm-gcc4 front end from a
+read-only subversion mirror at
+svn://anonsvn.opensource.apple.com/svn/llvm/trunk. </p>
</div>
<ul>
<li><tt>cd <i>where-you-want-llvm-to-live</i></tt>
- <li><tt>cvs -d :pserver:anon@llvm-cvs.cs.uiuc.edu:/var/cvs/llvm login</tt>
+ <li><tt>cvs -d :pserver:anon@llvm.org:/var/cvs/llvm login</tt>
<li>Hit the return key when prompted for the password.
- <li><tt>cvs -z3 -d :pserver:anon@llvm-cvs.cs.uiuc.edu:/var/cvs/llvm co
+ <li><tt>cvs -z3 -d :pserver:anon@llvm.org:/var/cvs/llvm co
llvm</tt>
</ul>
you get it from the CVS repository:</p>
<pre>
cd llvm/projects
- cvs -z3 -d :pserver:anon@llvm-cvs.cs.uiuc.edu:/var/cvs/llvm co llvm-test
+ cvs -z3 -d :pserver:anon@llvm.org:/var/cvs/llvm co llvm-test
</pre>
<p>By placing it in the <tt>llvm/projects</tt>, it will be automatically
configured by the LLVM configure script as well as automatically updated when
<p>If you would like to get the GCC 3.4 front end source code, you can also get it from the CVS repository:</p>
<pre>
- cvs -z3 -d :pserver:anon@llvm-cvs.cs.uiuc.edu:/var/cvs/llvm co llvm-gcc
+ cvs -z3 -d :pserver:anon@llvm.org:/var/cvs/llvm co llvm-gcc
</pre>
<p>Please note that you must follow <a href="CFEBuildInstrs.html">these
<p>The following environment variables are used by the <tt>configure</tt>
script to configure the build system:</p>
-<table>
+<table summary="LLVM configure script environment variables">
<tr><th>Variable</th><th>Purpose</th></tr>
<tr>
<td>CC</td>
dejagnu based test suite in <tt>llvm/test</tt>. If you don't specify this
option, the LLVM configure script will search for the tcl 8.4 and 8.3
releases.
- <p></p>
+ <br><br>
</dd>
<dt><i>--enable-optimized</i></dt>
<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></p>
+ <br><br>
</dd>
<dt><i>--enable-debug-runtime</i></dt>
<dd>
available
on all platforms. The default is dependent on platform, so it is best
to explicitly enable it if you want it.
- <p></p>
+ <br><br>
</dd>
<dt><i>--enable-targets=</i><tt>target-option</tt></dt>
<dd>Controls which targets will be built and linked into llc. The default
separated list of target names that you want available in llc. The target
names use all lower case. The current set of targets is: <br/>
<tt>alpha, ia64, powerpc, skeleton, sparc, x86</tt>.
- <p></p></dd>
+ <br><br></dd>
<dt><i>--enable-doxygen</i></dt>
<dd>Look for the doxygen program and enable construction of doxygen based
documentation from the source code. This is disabled by default because
<li>Change directory into the object root directory:
<br>
<tt>cd <i>OBJ_ROOT</i></tt>
- <p>
+ <br><br>
<li>Run the <tt>configure</tt> script located in the LLVM source tree:
<br>
<tt><i>SRC_ROOT</i>/configure --prefix=/install/path [other options]</tt>
- <p>
+ <br><br>
</ol>
</div>
<tt>--enable-optimized</tt> option was used during configuration). The
build system will compile the tools and libraries with debugging
information.
- <p>
+ <br><br>
<dt>Release (Optimized) Builds
<dd>
<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>
+ <br><br>
<dt>Profile Builds
<dd>
<dd>
Removes all files generated by the build. This includes object files,
generated C/C++ files, libraries, and executables.
- <p>
+ <br><br>
<dt><tt>gmake dist-clean</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>
+ <br><br>
<dt><tt>gmake install</tt>
<dd>
hierarchy
under $PREFIX, specified with <tt>./configure --prefix=[dir]</tt>, which
defaults to <tt>/usr/local</tt>.
- <p>
-
+ <br><br>
+
<dt><tt>gmake -C runtime install-bytecode</tt>
<dd>
Assuming you built LLVM into $OBJDIR, when this command is run, it will
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>
+ <br><br>
</dl>
<p>Please see the <a href="MakefileGuide.html">Makefile Guide</a> for further
<dt><tt>gmake ENABLE_OPTIMIZED=1</tt>
<dd>
Perform a Release (Optimized) build.
- <p>
+ <br><br>
<dt><tt>gmake ENABLE_OPTIMIZED=1 DISABLE_ASSERTIONS=1</tt>
<dd>
Perform a Release (Optimized) build without assertions enabled.
- <p>
+ <br><br>
<dt><tt>gmake ENABLE_PROFILING=1</tt>
<dd>
Perform a Profiling build.
- <p>
+ <br><br>
<dt><tt>gmake VERBOSE=1</tt>
<dd>
Print what <tt>gmake</tt> is doing on standard output.
- <p>
+ <br><br>
<dt><tt>gmake TOOL_VERBOSE=1</tt></dt>
<dd>Ask each tool invoked by the makefiles to print out what it is doing on
the standard output. This also implies <tt>VERBOSE=1</tt>.
- <p></dd>
+ <br><br></dd>
</dl>
<p>Every directory in the LLVM object tree includes a <tt>Makefile</tt> to build
<dt>Libraries
<dd><tt><i>OBJ_ROOT</i>/Debug/lib</tt>
</dl>
- <p>
+ <br><br>
<dt>Release Builds
<dd>
<dt>Libraries
<dd><tt><i>OBJ_ROOT</i>/Release/lib</tt>
</dl>
- <p>
+ <br><br>
<dt>Profile Builds
<dd>
information is in the <a href="CommandGuide/index.html">Command Guide</a>.</p>
<dl>
- <dt><tt><b>analyze</b></tt></dt>
- <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.</dd>
<dt><tt><b>bugpoint</b></tt></dt>
<dd><tt>bugpoint</tt> is used to debug
</dd>
<dt><tt><b>opt</b></tt></dt>
- <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.</dd>
+ <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.<br/>
+ <dd><tt>opt</tt> can also be 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.</dd>
</dl>
</div>
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>
+ manual, run <tt>`perldoc codegen-diff'</tt>.<br><br>
<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
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>
+ preferred way of updating the tree.<br><br>
<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>
+ the <tt>README</tt> file in that directory.<br><br>
<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>
-
+ tree.<br><br>
+
<dt><tt><b>llvmgrep</b></tt></dt>
<dd>This little tool performs an "egrep -H -n" on each source file in LLVM and
passes to it a regular expression provided on <tt>llvmgrep</tt>'s command
<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>
+ causing a re-linking of LLC.<br><br>
<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.org/">LLVM homepage</a>.<p>
+ the <a href="http://llvm.org/">LLVM homepage</a>.<br><br>
<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>
+ files.<br><br>
<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>
+ the <tt>README</tt> file in that directory.<br><br>
</dl>
</div>
<!-- *********************************************************************** -->
+<div class="doc_text">
+<p>This section gives an example of using LLVM. Since we are currently
+transitioning from llvm-gcc3 to llvm-gcc4, we include examples for both.
+</p>
+
+<p><b>Note:</b> The <i>gcc4</i> frontend's invocation is <b><i>considerably different</i></b>
+from the previous <i>gcc3</i> frontend. In particular, the <i>gcc4</i> frontend <b><i>does not</i></b>
+create bytecode by default: <i>gcc4</i> produces native code. As the example below illustrates,
+the '--emit-llvm' flag is needed to produce LLVM bytecode output. For <i>makefiles</i> and
+<i>configure</i> scripts, the CFLAGS variable needs '--emit-llvm' to produce bytecode
+output.</p>
+</div>
+
+<!-- ======================================================================= -->
+<div class="doc_subsection"><a name="tutorial4">Example with llvm-gcc4</a></div>
+
+<div class="doc_text">
+
+<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>
+
+ <li><p>Next, compile the C file into a native executable:</p>
+
+ <p><tt>% llvm-gcc hello.c -o hello</tt></p>
+
+ <p>Note that llvm-gcc works just like GCC by default. The standard -S and
+ -c arguments work as usual (producing a native .s or .o file,
+ respectively). </p>
+
+ <li><p>Next, compile the C file into a LLVM bytecode file:</p>
+ <p><tt>% llvm-gcc -O3 -emit-llvm hello.c -c -o hello.bc</tt></p>
+
+ <p>The -emit-llvm option can be used with the -S or -c options to emit an
+ LLVM ".ll" or ".bc" file (respectively) for the code. This allows you
+ to use the <a href="CommandGuide/index.html">standard LLVM tools</a> on
+ the bytecode file.</p>
+
+ <p>Unlike llvm-gcc3, llvm-gcc4 correctly responds to -O[0123] arguments.
+ </p></li>
+
+ <li><p>Run the program in both forms. To run the program, use:</p>
+
+ <p><tt>% ./hello</tt></p>
+
+ <p>and</p>
+
+ <p><tt>% lli hello.bc</tt></p>
+
+ <p>The second examples shows how to invoke the LLVM JIT, <a
+ href="CommandGuide/html/lli.html">lli</a>.</p></li>
+
+ <li><p>Use the <tt>llvm-dis</tt> utility to take a look at the LLVM assembly
+ code:</p>
+
+ <p><tt>% llvm-dis < hello.bc | less</tt><br><br></li>
+
+ <li><p>Compile the program to native assembly using the LLC code
+ generator:</p>
+
+ <p><tt>% llc hello.bc -o hello.s</tt></p>
+
+ <li><p>Assemble the native assembly language file into a program:</p>
+
+ <p><b>Solaris:</b><tt>% /opt/SUNWspro/bin/cc -xarch=v9 hello.s -o hello.native</tt></p>
+ <p><b>Others:</b><tt>% gcc hello.s -o hello.native</tt></p>
+
+ <li><p>Execute the native code program:</p>
+
+ <p><tt>% ./hello.native</tt></p>
+
+ <p>Note that using llvm-gcc to compile directly to native code (i.e. when
+ the -emit-llvm option is not present) does steps 6/7/8 for you.</p>
+ </li>
+
+</ol>
+
+</div>
+
+<!-- ======================================================================= -->
+<div class="doc_subsection"><a name="tutorial3">Example with llvm-gcc3</a></div>
+
<div class="doc_text">
<ol>
<li><p>Run the program. To make sure the program ran, execute one of the
following commands:</p>
-
+
<p><tt>% ./hello</tt></p>
-
+
<p>or</p>
<p><tt>% lli hello.bc</tt></p></li>
<li><p>Use the <tt>llvm-dis</tt> utility to take a look at the LLVM assembly
code:</p>
- <p><tt>% llvm-dis < hello.bc | less</tt><p></li>
+ <p><tt>% llvm-dis < hello.bc | less</tt><br><br></li>
<li><p>Compile the program to native assembly using the LLC code
generator:</p>
projects / oota-llvm.git / blobdiff