<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>Getting Started with LLVM System</title>
- <link rel="stylesheet" href="llvm.css" type="text/css">
+ <link rel="stylesheet" href="_static/llvm.css" type="text/css">
</head>
<body>
<li><a href="#unpack">Unpacking the LLVM Archives</a></li>
<li><a href="#checkout">Checkout LLVM from Subversion</a></li>
<li><a href="#git_mirror">LLVM GIT mirror</a></li>
- <li><a href="#installcf">Install the GCC Front End</a></li>
<li><a href="#config">Local LLVM Configuration</a></li>
<li><a href="#compile">Compiling the LLVM Suite Source Code</a></li>
<li><a href="#cross-compile">Cross-Compiling LLVM</a></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="#tutorial4">Example with Clang</a></li>
</ol>
<li><a href="#problems">Common Problems</a>
<li><a href="#links">Links</a>
<p>First, LLVM comes in three 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, bitcode analyzer and bitcode optimizer. It
-also contains basic regression tests 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
-GCC that compiles C and C++ code into LLVM bitcode. Currently, the GCC front
-end uses the GCC parser to convert code to LLVM. Once
-compiled into LLVM bitcode, a program can be manipulated with the LLVM tools
-from the LLVM suite.</p>
+needed to use LLVM. It contains an assembler, disassembler, bitcode
+analyzer and bitcode optimizer. It also contains basic regression tests that
+can be used to test the LLVM tools and the Clang front end.</p>
+
+<p>The second piece is the <a href="http://clang.llvm.org/">Clang</a> front end.
+This component compiles C, C++, Objective C, and Objective C++ code into LLVM
+bitcode. Once compiled into LLVM bitcode, a program can be manipulated with the
+LLVM tools from the LLVM suite.
+</p>
<p>
There is a third, optional piece called Test Suite. It is a suite of programs
<div>
+<p>The LLVM Getting Started documentation may be out of date. So, the Clang
+<a href="http://clang.llvm.org/get_started.html">Getting Started</a> page might
+also be a good place to start.</p>
+
<p>Here's the short story for getting up and running quickly with LLVM:</p>
<ol>
<li>Read the documentation.</li>
<li>Read the documentation.</li>
<li>Remember that you were warned twice about reading the documentation.</li>
- <li>Install the llvm-gcc-4.2 front end if you intend to compile C or C++
- (see <a href="#installcf">Install the GCC Front End</a> for details):
- <ol>
- <li><tt>cd <i>where-you-want-the-C-front-end-to-live</i></tt></li>
- <li><tt>gunzip --stdout llvm-gcc-4.2-<i>version</i>-<i>platform</i>.tar.gz | tar -xvf -</tt></li>
- <li><tt><i>install-binutils-binary-from-MinGW</i></tt> (Windows only)</li>
- <li>Note: If the binary extension is "<tt>.bz</tt>" use <tt>bunzip2</tt> instead of <tt>gunzip</tt>.</li>
- <li>Note: On Windows, use <a href="http://www.7-zip.org/">7-Zip</a> or a similar archiving tool.</li>
- <li>Add <tt>llvm-gcc</tt>'s "<tt>bin</tt>" directory to your <tt>PATH</tt> environment variable.</li>
- </ol></li>
- <li>Get the LLVM Source Code
+ <li>Checkout LLVM:
<ul>
- <li>With the distributed files (or use <a href="#checkout">SVN</a>):
- <ol>
- <li><tt>cd <i>where-you-want-llvm-to-live</i></tt>
- <li><tt>gunzip --stdout llvm-<i>version</i>.tar.gz | tar -xvf -</tt>
- </ol></li>
-
- </ul></li>
+ <li><tt>cd <i>where-you-want-llvm-to-live</i></tt>
+ <li><tt>svn co http://llvm.org/svn/llvm-project/llvm/trunk llvm</tt></li>
+ </ul>
+ </li>
- <li><b>[Optional]</b> Get the Test Suite Source Code
+ <li>Checkout Clang:
<ul>
- <li>With the distributed files (or use <a href="#checkout">SVN</a>):
- <ol>
- <li><tt>cd <i>where-you-want-llvm-to-live</i></tt>
- <li><tt>cd llvm/projects</tt>
- <li><tt>gunzip --stdout llvm-test-<i>version</i>.tar.gz | tar -xvf -</tt>
- <li><tt>mv llvm-test-<i>version</i> test-suite</tt>
- </ol></li>
+ <li><tt>cd <i>where-you-want-llvm-to-live</i></tt>
+ <li><tt>cd llvm/tools</tt>
+ <li><tt>svn co http://llvm.org/svn/llvm-project/cfe/trunk clang</tt></li>
+ </ul>
+ </li>
- </ul></li>
+ <li>Checkout Compiler-RT:
+ <ul>
+ <li><tt>cd <i>where-you-want-llvm-to-live</i></tt>
+ <li><tt>cd llvm/projects</tt>
+ <li><tt>svn co http://llvm.org/svn/llvm-project/compiler-rt/trunk
+ compiler-rt</tt></li>
+ </ul>
+ </li>
+ <li>Get the Test Suite Source Code <b>[Optional]</b>
+ <ul>
+ <li><tt>cd <i>where-you-want-llvm-to-live</i></tt>
+ <li><tt>cd llvm/projects</tt>
+ <li><tt>svn co http://llvm.org/svn/llvm-project/test-suite/trunk test-suite</tt></li>
+ </ul>
+ </li>
- <li>Configure the LLVM Build Environment
- <ol>
+ <li>Configure and build LLVM and Clang:
+ <ul>
<li><tt>cd <i>where-you-want-to-build-llvm</i></tt></li>
- <li><tt><i>/path/to/llvm/</i>configure [options]</tt><br>
- Some common options:
+ <li><tt>mkdir build</tt> (for building without polluting the source dir)</li>
+ <li><tt>cd build</tt></li>
+ <li><tt>../llvm/configure [options]</tt>
+ <br>Some common options:
<ul>
- <li><tt>--prefix=<i>directory</i></tt>
- <p>Specify for <i>directory</i> the full pathname of where you
+ <li><tt>--prefix=<i>directory</i></tt> -
+ Specify for <i>directory</i> the full pathname of where you
want the LLVM tools and libraries to be installed (default
- <tt>/usr/local</tt>).</p></li>
- <li><tt>--with-llvmgccdir=<i>directory</i></tt>
- <p>Optionally, specify for <i>directory</i> the full pathname of the
- C/C++ front end installation to use with this LLVM configuration. If
- not specified, the PATH will be searched. This is only needed if you
- want to run test-suite or do some special kinds of LLVM builds.</p></li>
- <li><tt>--enable-spec2000=<i>directory</i></tt>
- <p>Enable the SPEC2000 benchmarks for testing. The SPEC2000
- benchmarks should be available in
- <tt><i>directory</i></tt>.</p></li>
+ <tt>/usr/local</tt>).</li>
</ul>
- </ol></li>
- <li>Build the LLVM Suite:
- <ol>
- <li><tt>gmake -k |& tee gnumake.out
- # this is csh or tcsh syntax</tt></li>
- <li>If you get an "internal compiler error (ICE)" or test failures, see
- <a href="#brokengcc">below</a>.</li>
- </ol>
+ <ul>
+ <li><tt>--enable-optimized</tt> -
+ Compile with optimizations enabled (default is NO).</li>
+ </ul>
+
+ <ul>
+ <li><tt>--enable-assertions</tt> -
+ Compile with assertion checks enabled (default is YES).</li>
+ </ul>
+ </li>
+ <li><tt>make [-j]</tt> - The -j specifies the number of jobs (commands) to
+ run simultaneously. This builds both LLVM and Clang for Debug+Asserts mode.
+ The --enabled-optimized configure option is used to specify a Release build.</li>
+ <li><tt>make check-all</tt> -
+ This run the regression tests to ensure everything is in working order.</li>
+ <li><tt>make update</tt> -
+ This command is used to update all the svn repositories at once, rather then
+ having to <tt>cd</tt> into the individual repositories and running
+ <tt>svn update</tt>.</li>
+ <li>It is also possible to use CMake instead of the makefiles. With CMake
+ it is also possible to generate project files for several IDEs: Eclipse
+ CDT4, CodeBlocks, Qt-Creator (use the CodeBlocks generator), KDevelop3.</li>
+ <li>If you get an "internal compiler error (ICE)" or test failures, see
+ <a href="#brokengcc">below</a>.</li>
+
+ </ul>
+ </li>
</ol>
<p>Consult the <a href="#starting">Getting Started with LLVM</a> section for
detailed information on configuring and compiling LLVM. See <a
href="#environment">Setting Up Your Environment</a> for tips that simplify
-working with the
GCC front end and LLVM tools. Go to <a href="#layout">Program
+working with the
Clang front end and LLVM tools. Go to <a href="#layout">Program
Layout</a> to learn about the layout of the source code tree.</p>
</div>
<tr>
<td>Windows</td>
<td>x86<sup><a href="#pf_1">1</a></sup></td>
- <td>Visual Studio 200
5 SP1 or higher<sup><a href="#pf_4">4</a>,<a href="#pf_5">5</a></sup></td>
+ <td>Visual Studio 200
8 or higher<sup><a href="#pf_4">4</a>,<a href="#pf_5">5</a></sup></td>
<tr>
<td>AIX<sup><a href="#pf_3">3</a>,<a href="#pf_4">4</a></sup></td>
<td>PowerPC</td>
generation should work as well, although the generated native code may not work
on your platform.</p>
-<p>The GCC front end is not very portable at the moment. If you want to get it
-to work on another platform, you can download a copy of the source and <a
-href="GCCFEBuildInstrs.html">try to compile it</a> on your platform.</p>
-
</div>
<!-- ======================================================================= -->
<tr>
<td><a href="http://www.perl.com/download.csp">perl</a></td>
<td>≥5.6.0</td>
- <td>Nightly tester, utilities</td>
+ <td>Utilities</td>
</tr>
<tr>
<p>LLVM is very demanding of the host C++ compiler, and as such tends to expose
bugs in the compiler. In particular, several versions of GCC crash when trying
-to compile LLVM. We routinely use GCC 3.3.3, 3.4.0, and Apple 4.0.1
-successfully with them (however, see important notes below). Other versions
-of GCC will probably work as well. GCC versions listed
+to compile LLVM. We routinely use GCC 4.2 (and higher) or Clang.
+Other versions of GCC will probably work as well. GCC versions listed
here are known to not work. If you are using one of these versions, please try
to upgrade your GCC to something more recent. If you run into a problem with a
version of GCC not listed here, please <a href="mailto:llvmdev@cs.uiuc.edu">let
the "<tt>convert_from_eh_region_ranges_1</tt>" GCC function.</p>
<p><b>Cygwin GCC 3.3.3</b>: The version of GCC 3.3.3 commonly shipped with
- Cygwin does not work. Please <a href="GCCFEBuildInstrs.html#cygwin">upgrade
- to a newer version</a> if possible.</p>
+ Cygwin does not work.</p>
<p><b>SuSE GCC 3.3.3</b>: The version of GCC 3.3.3 shipped with SuSE 9.1 (and
possibly others) does not compile LLVM correctly (it appears that exception
handling is broken in some cases). Please download the FSF 3.3.3 or upgrade
can be the same as SRC_ROOT).
<br><br>
- <dt>LLVMGCCDIR
- <dd>
- This is where the LLVM GCC Front End is installed.
- <p>
- For the pre-built GCC front end binaries, the LLVMGCCDIR is
- <tt>llvm-gcc/<i>platform</i>/llvm-gcc</tt>.
</dl>
</div>
configured by the LLVM configure script as well as automatically updated when
you run <tt>svn update</tt>.</p>
-<p>If you would like to get the GCC front end source code, you can also get it
-and build it yourself. Please follow <a href="GCCFEBuildInstrs.html">these
-instructions</a> to successfully get and build the LLVM GCC front-end.</p>
-
</div>
<!-- ======================================================================= -->
now mirrors reflect only <tt>trunk</tt> for each project. You can do the
read-only GIT clone of LLVM via:</p>
-<pre>
+<pre class="doc_code">
git clone http://llvm.org/git/llvm.git
</pre>
<p>If you want to check out clang too, run:</p>
-<pre>
+<pre class="doc_code">
git clone http://llvm.org/git/llvm.git
cd llvm/tools
git clone http://llvm.org/git/clang.git
</pre>
+<p>
+Since the upstream repository is in Subversion, you should use
+<tt>"git pull --rebase"</tt>
+instead of <tt>"git pull"</tt> to avoid generating a non-linear
+history in your clone.
+To configure <tt>"git pull"</tt> to pass <tt>--rebase</tt> by default
+on the master branch, run the following command:
+</p>
+
+<pre class="doc_code">
+git config branch.master.rebase true
+</pre>
+
+<h4>Sending patches with Git</h4>
+<div>
+<p>
+Please read <a href="DeveloperPolicy.html#patches">Developer Policy</a>, too.
+</p>
+
+<p>
+Assume <tt>master</tt> points the upstream and <tt>mybranch</tt> points your
+working branch, and <tt>mybranch</tt> is rebased onto <tt>master</tt>.
+At first you may check sanity of whitespaces:
+</p>
+
+<pre class="doc_code">
+git diff --check master..mybranch
+</pre>
+
+<p>
+The easiest way to generate a patch is as below:
+</p>
+
+<pre class="doc_code">
+git diff master..mybranch > /path/to/mybranch.diff
+</pre>
+
+<p>
+It is a little different from svn-generated diff. git-diff-generated diff has
+prefixes like <tt>a/</tt> and <tt>b/</tt>. Don't worry, most developers might
+know it could be accepted with <tt>patch -p1 -N</tt>.
+</p>
+
+<p>
+But you may generate patchset with git-format-patch. It generates
+by-each-commit patchset. To generate patch files to attach to your article:
+</p>
+
+<pre class="doc_code">
+git format-patch --no-attach master..mybranch -o /path/to/your/patchset
+</pre>
+
+<p>
+If you would like to send patches directly, you may use git-send-email or
+git-imap-send. Here is an example to generate the patchset in Gmail's [Drafts].
+</p>
+
+<pre class="doc_code">
+git format-patch --attach master..mybranch --stdout | git imap-send
+</pre>
+
+<p>
+Then, your .git/config should have [imap] sections.
+</p>
+
+<pre class="doc_code">
+[imap]
+ host = imaps://imap.gmail.com
+ user = <em>your.gmail.account</em>@gmail.com
+ pass = <em>himitsu!</em>
+ port = 993
+ sslverify = false
+; in English
+ folder = "[Gmail]/Drafts"
+; example for Japanese, "Modified UTF-7" encoded.
+ folder = "[Gmail]/&Tgtm+DBN-"
+; example for Traditional Chinese
+ folder = "[Gmail]/&g0l6Pw-"
+</pre>
+
+</div>
+
+<h4>For developers to work with git-svn</h4>
+<div>
+
<p>To set up clone from which you can submit code using
<tt>git-svn</tt>, run:</p>
-<pre>
-git clone http://llvm.org/git/llvm
+<pre class="doc_code">
+git clone http://llvm.org/git/llvm.git
cd llvm
git svn init https://llvm.org/svn/llvm-project/llvm/trunk --username=<username>
git config svn-remote.svn.fetch :refs/remotes/origin/master
# If you have clang too:
cd tools
-git clone http://llvm.org/git/clang.git clang
+git clone http://llvm.org/git/clang.git
cd clang
git svn init https://llvm.org/svn/llvm-project/cfe/trunk --username=<username>
git config svn-remote.svn.fetch :refs/remotes/origin/master
<p>To update this clone without generating git-svn tags that conflict
with the upstream git repo, run:</p>
-<pre>
+<pre class="doc_code">
git fetch && (cd tools/clang && git fetch) # Get matching revisions of both trees.
git checkout master
git svn rebase -l
dcommit</code> stops working, complaining about files with uncommitted
changes. The fix is to rebuild the metadata:</p>
-<pre>
+<pre class="doc_code">
rm -rf .git/svn
git svn rebase -l
</pre>
</div>
-<!-- ======================================================================= -->
-<h3>
- <a name="installcf">Install the GCC Front End</a>
-</h3>
-
-<div>
-
-<p>Before configuring and compiling the LLVM suite (or if you want to use just the LLVM
-GCC front end) you can optionally extract the front end from the binary distribution.
-It is used for running the LLVM test-suite and for compiling C/C++ programs. Note that
-you can optionally <a href="GCCFEBuildInstrs.html">build llvm-gcc yourself</a> after building the
-main LLVM repository.</p>
-
-<p>To install the GCC front end, do the following (on Windows, use an archival tool
-like <a href="http://www.7-zip.org/">7-zip</a> that understands gzipped tars):</p>
-
-<ol>
- <li><tt>cd <i>where-you-want-the-front-end-to-live</i></tt></li>
- <li><tt>gunzip --stdout llvm-gcc-4.2-<i>version</i>-<i>platform</i>.tar.gz | tar -xvf
- -</tt></li>
-</ol>
-
-<p>Once the binary is uncompressed, if you're using a *nix-based system, add a symlink for
-<tt>llvm-gcc</tt> and <tt>llvm-g++</tt> to some directory in your path. If you're using a
-Windows-based system, add the <tt>bin</tt> subdirectory of your front end installation directory
-to your <tt>PATH</tt> environment variable. For example, if you uncompressed the binary to
-<tt>c:\llvm-gcc</tt>, add <tt>c:\llvm-gcc\bin</tt> to your <tt>PATH</tt>.</p>
-
-<p>If you now want to build LLVM from source, when you configure LLVM, it will
-automatically detect <tt>llvm-gcc</tt>'s presence (if it is in your path) enabling its
-use in test-suite. Note that you can always build or install <tt>llvm-gcc</tt> at any
-point after building the main LLVM repository: just reconfigure llvm and
-test-suite will pick it up.
-</p>
-
-<p>As a convenience for Windows users, the front end binaries for MinGW/x86 include
-versions of the required w32api and mingw-runtime binaries. The last remaining step for
-Windows users is to simply uncompress the binary binutils package from
-<a href="http://mingw.org/">MinGW</a> into your front end installation directory. While the
-front end installation steps are not quite the same as a typical manual MinGW installation,
-they should be similar enough to those who have previously installed MinGW on Windows systems.</p>
-
-<p>To install binutils on Windows:</p>
-
-<ol>
- <li><tt><i>download GNU Binutils from <a href="http://sourceforge.net/projects/mingw/files/">MinGW Downloads</a></i></tt></li>
- <li><tt>cd <i>where-you-uncompressed-the-front-end</i></tt></li>
- <li><tt><i>uncompress archived binutils directories (not the tar file) into the current directory</i></tt></li>
-</ol>
-
-<p>The binary versions of the LLVM GCC front end may not suit all of your needs. For
-example, the binary distribution may include an old version of a system header
-file, not "fix" a header file that needs to be fixed for GCC, or it may be linked with
-libraries not available on your system. In cases like these, you may want to try
-<a href="GCCFEBuildInstrs.html">building the GCC front end from source</a>. Thankfully,
-this is much easier now than it was in the past.</p>
-
-<p>We also do not currently support updating of the GCC front end by manually overlaying
-newer versions of the w32api and mingw-runtime binary packages that may become available
-from MinGW. At this time, it's best to think of the MinGW LLVM GCC front end binary as
-a self-contained convenience package that requires Windows users to simply download and
-uncompress the GNU Binutils binary package from the MinGW project.</p>
-
-<p>Regardless of your platform, if you discover that installing the LLVM GCC front end
-binaries is not as easy as previously described, or you would like to suggest improvements,
-please let us know how you would like to see things improved by dropping us a note on our
-<a href="http://llvm.org/docs/#maillist">mailing list</a>.</p>
-
</div>
<!-- ======================================================================= -->
<p>The following options can be used to set or enable LLVM specific options:</p>
<dl>
- <dt><i>--with-llvmgccdir</i></dt>
- <dd>Path to the LLVM C/C++ FrontEnd to be used with this LLVM configuration.
- The value of this option should specify the full pathname of the C/C++ Front
- End to be used. If this option is not provided, the PATH will be searched for
- a program named <i>llvm-gcc</i> and the C/C++ FrontEnd install directory will
- be inferred from the path found. If the option is not given, and no llvm-gcc
- can be found in the path then a warning will be produced by
- <tt>configure</tt> indicating this situation. LLVM may still be built with
- the <tt>tools-only</tt> target but attempting to build the runtime libraries
- will fail as these libraries require llvm-gcc and llvm-g++. See
- <a href="#installcf">Install the GCC Front End</a> for details on installing
- the C/C++ Front End. See
- <a href="GCCFEBuildInstrs.html">Bootstrapping the LLVM C/C++ Front-End</a>
- for details on building the C/C++ Front End.</dd>
- <dt><i>--with-tclinclude</i></dt>
- <dd>Path to the tcl include directory under which <tt>tclsh</tt> can be
- found. Use this if you have multiple tcl installations on your machine and you
- want to use a specific one (8.x) for LLVM. LLVM only uses tcl for running the
- 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.
- <br><br>
- </dd>
<dt><i>--enable-optimized</i></dt>
<dd>
Enables optimized compilation (debugging symbols are removed
selected as the target of the build host. You can also specify a comma
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>.
+ <tt>arm, cpp, hexagon, mblaze, mips, mipsel, msp430, powerpc, ptx, sparc, spu, x86, x86_64, xcore</tt>.
<br><br></dd>
<dt><i>--enable-doxygen</i></dt>
<dd>Look for the doxygen program and enable construction of doxygen based
<dd> This directory contains files that describe various target architectures
for code generation. For example, the <tt>llvm/lib/Target/X86</tt>
directory holds the X86 machine description while
- <tt>llvm/lib/Target/CBackend</tt> implements the LLVM-to-C converter.</dd>
+ <tt>llvm/lib/Target/ARM</tt> implements the ARM backend.</dd>
<dt><tt><b>llvm/lib/CodeGen/</b></tt></dt>
<dd> This directory contains the major parts of the code generator: Instruction
at runtime in both interpreted and JIT compiled fashions.</dd>
<dt><tt><b>llvm/lib/Support/</b></tt></dt>
- <dd> This directory contains the source code that corresponds to the header
- files located in <tt>llvm/include/Support/</tt>.</dd>
-
- <!--FIXME: obsoleted -->
- <dt><tt><b>llvm/lib/System/</b></tt></dt>
- <dd>This directory contains the operating system abstraction layer that
- shields LLVM from platform-specific coding.</dd>
+ <dd> This directory contains the source code that corresponds to the header
+ files located in <tt>llvm/include/ADT/</tt>
+ and <tt>llvm/include/Support/</tt>.</dd>
</dl>
</div>
<div>
<p>This directory contains libraries which are compiled into LLVM bitcode and
-used when linking programs with the GCC front end. Most of these libraries are
+used when linking programs with the Clang front end. Most of these libraries are
skeleton versions of real libraries; for example, libc is a stripped down
version of glibc.</p>
href="HowToSubmitABug.html">HowToSubmitABug.html</a> for more information
on using <tt>bugpoint</tt>.</dd>
- <dt><tt><b>llvmc</b></tt></dt>
- <dd>The LLVM Compiler Driver. This program can
- be configured to utilize both LLVM and non-LLVM compilation tools to enable
- pre-processing, translation, optimization, assembly, and linking of programs
- all from one command line. <tt>llvmc</tt> also takes care of processing the
- dependent libraries found in bitcode. This reduces the need to get the
- traditional <tt>-l<name></tt> options right on the command line. Please
- note that this tool, while functional, is still experimental and not feature
- complete.</dd>
-
<dt><tt><b>llvm-ar</b></tt></dt>
<dd>The archiver produces an archive containing
the given LLVM bitcode files, optionally with an index for faster
<dd>The disassembler transforms the LLVM bitcode to human readable
LLVM assembly.</dd>
- <dt><tt><b>llvm-ld</b></tt></dt>
- <dd><tt>llvm-ld</tt> is a general purpose and extensible linker for LLVM.
- This is the linker invoked by <tt>llvmc</tt>. It performs standard link time
- optimizations and allows optimization modules to be loaded and run so that
- language specific optimizations can be applied at link time.</dd>
-
<dt><tt><b>llvm-link</b></tt></dt>
<dd><tt>llvm-link</tt>, not surprisingly, links multiple LLVM modules into
a single program.</dd>
directory, switch to directory <tt>llvm/tools/llc</tt> and build it,
causing a re-linking of LLC.<br><br>
- <dt><tt><b>NewNightlyTest.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>.<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
<!-- *********************************************************************** -->
<div>
-<p>This section gives an example of using LLVM. llvm-gcc3 is now obsolete,
-so we only include instructions for llvm-gcc4.
-</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 bitcode by default: <i>gcc4</i> produces native code. As the example below illustrates,
-the '--emit-llvm' flag is needed to produce LLVM bitcode output. For <i>makefiles</i> and
-<i>configure</i> scripts, the CFLAGS variable needs '--emit-llvm' to produce bitcode
-output.</p>
+<p>This section gives an example of using LLVM with the Clang front end.</p>
<!-- ======================================================================= -->
<h3>
- <a name="tutorial4">Example with llvm-gcc4</a>
+ <a name="tutorial4">Example with clang</a>
</h3>
<div>
<li><p>Next, compile the C file into a native executable:</p>
- <div class="doc_code"><pre>% llvm-gcc hello.c -o hello</pre></div>
+ <div class="doc_code"><pre>% clang hello.c -o hello</pre></div>
- <p>Note that llvm-gcc works just like GCC by default. The standard -S and
+ <p>Note that clang 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>
<li><p>Next, compile the C file into a LLVM bitcode file:</p>
<div class="doc_code">
- <pre>% llvm-gcc -O3 -emit-llvm hello.c -c -o hello.bc</pre></div>
+ <pre>% clang -O3 -emit-llvm hello.c -c -o hello.bc</pre></div>
<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 bitcode file.</p>
-
- <p>Unlike llvm-gcc3, llvm-gcc4 correctly responds to -O[0123] arguments.
- </p></li>
+ the bitcode file.</p></li>
<li><p>Run the program in both forms. To run the program, use:</p>
<div class="doc_code"><pre>% ./hello.native</pre></div>
- <p>Note that using llvm-gcc to compile directly to native code (i.e. when
+ <p>Note that using clang 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>
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