<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>
<p>The second piece is the GCC front end. This component provides a version of
GCC that compiles C and C++ code into LLVM bytecode. Currently, the GCC front
-end is a modified version of GCC 3.4 (we track the GCC 3.4 development). Once
+end uses the GCC parser to convert code to LLVM. Once
compiled into LLVM bytecode, a program can be manipulated with the LLVM tools
from the LLVM suite.</p>
<li>Install the GCC front end if you intend to compile C or C++:
<ol>
<li><tt>cd <i>where-you-want-the-C-front-end-to-live</i></tt></li>
- <li><tt>gunzip --stdout cfrontend.<i>platform</i>.tar.gz | tar -xvf -</tt>
+ <li><tt>gunzip --stdout llvm-gcc.<i>platform</i>.tar.gz | tar -xvf -</tt>
</li>
- <li><tt>cd cfrontend/<i>platform</i><br>
+ <li><tt>cd llvm-gcc3.4/<i>platform</i> (llvm-gcc3.4 only)<br>
./fixheaders</tt></li>
- <li>Add the cfrontend's "bin" directory to your PATH variable.</li>
+ <li>Add llvm-gcc's "bin" directory to your PATH variable.</li>
</ol></li>
<li>Get the LLVM Source Code
<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)" see <a href="#brokengcc">below</a>.</li>
+ <li>If you get an "internal compiler error (ICE)" or test failures, see
+ <a href="#brokengcc">below</a>.</li>
</ol>
</ol>
<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 below). Other versions of GCC will
-probably work as well. GCC versions listed
+successfully with them (however, see important notes below). 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
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
to a newer version of GCC.</p>
+<p><b>GCC 3.4.0</b> on linux/x86 (32-bit)</b>: GCC miscompiles portions of the
+ code generator, causing an infinite loop in the llvm-gcc build when built
+ with optimizations enabled (i.e. a release build).</p>
+<p><b>GCC 3.4.2</b> on linux/x86 (32-bit)</b>: GCC miscompiles portions of the
+ code generator at -O3, as with 3.4.0. However gcc 3.4.2 (unlike 3.4.0)
+ correctly compiles LLVM at -O2. A work around is to build release LLVM
+ builds with "make ENABLE_OPTIMIZED=1 OPTIMIZE_OPTION=-O2 ..."</p>
+<p><b>GCC 3.4.x</b> on X86-64/amd64</b>: GCC <a href="http://llvm.org/PR1056">
+ miscompiles portions of LLVM</a>.</p>
<p><b>IA-64 GCC 4.0.0</b>: The IA-64 version of GCC 4.0.0 is known to
miscompile LLVM.</p>
<p><b>Apple Xcode 2.3</b>: GCC crashes when compiling LLVM at -O3 (which is the
<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>GCC 4.1.1 on X86-64/amd64</b>: GCC <a href="http://llvm.org/PR1063">
+ miscompiles portions of LLVM</a> when compiling llvm itself into 64-bit
+ code. LLVM will appear to mostly work but will be buggy, e.g. failing
+ portions of its testsuite.</p>
+<p><b>GCC 4.1.2 on OpenSUSE</b>: Seg faults during libstdc++ build and on x86_64
+platforms compiling md5.c gets a mangled constant.</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>
This is where the LLVM GCC Front End is installed.
<p>
For the pre-built GCC front end binaries, the LLVMGCCDIR is
- <tt>cfrontend/<i>platform</i>/llvm-gcc</tt>.
+ <tt>llvm-gcc/<i>platform</i>/llvm-gcc</tt>.
</dl>
</div>
<dt><tt>llvm-test-x.y.tar.gz</tt></dt>
<dd>Source release for the LLVM test suite.</dd>
- <dt><tt>cfrontend-x.y.source.tar.gz</tt></dt>
- <dd>Source release of the GCC front end.<br/></dd>
-
- <dt><tt>cfrontend-x.y.i686-redhat-linux-gnu.tar.gz</tt></dt>
- <dd>Binary release of the GCC front end for Linux/x86.<br/></dd>
-
<dt><tt>llvm-gcc4-x.y.source.tar.gz</tt></dt>
<dd>Source release of the llvm-gcc4 front end. See README.LLVM in the root
directory for build instructions.<br/></dd>
- <dt><tt>llvm-gcc4-x.y.powerpc-apple-darwin8.6.0.tar.gz</tt></dt>
- <dd>Binary release of the llvm-gcc4 front end for MacOS X/PowerPC.<br/></dd>
+ <dt><tt>llvm-gcc4-x.y-platform.tar.gz</tt></dt>
+ <dd>Binary release of the llvm-gcc4 front end for a specific platform.<br/></dd>
- <dt><tt>llvm-gcc4-x.y.i686-apple-darwin8.6.1.tar.gz</tt></dt>
- <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
labels:</p>
<ul>
+<li>Release 2.0: <b>RELEASE_20</b></li>
+<li>Release 1.9: <b>RELEASE_19</b></li>
+<li>Release 1.8: <b>RELEASE_18</b></li>
<li>Release 1.7: <b>RELEASE_17</b></li>
<li>Release 1.6: <b>RELEASE_16</b></li>
<li>Release 1.5: <b>RELEASE_15</b></li>
configured by the LLVM configure script as well as automatically updated when
you run <tt>cvs update</tt>.</p>
-<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.org:/var/cvs/llvm co llvm-gcc
-</pre>
-
-<p>Please note that you must follow <a href="CFEBuildInstrs.html">these
-instructions</a> to successfully build the LLVM GCC front-end.</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="CFEBuildInstrs.html">these
+instructions</a> to successfully get and build the LLVM GCC front-end.</p>
</div>
<div class="doc_text">
-<p>Before configuring and compiling the LLVM suite, you need to extract the LLVM
-GCC front end from the binary distribution. It is used for building the
-bytecode libraries later used by the GCC front end for linking programs, and its
-location must be specified when the LLVM suite is configured.</p>
+<p>Before configuring and compiling the LLVM suite, you can optionally extract the
+LLVM GCC front end from the binary distribution. It is used for running the
+llvm-test testsuite and for compiling C/C++ programs. Note that you can optionally
+<a href="CFEBuildInstrs.html">build llvm-gcc yourself</a> after building the
+main LLVM repository.</p>
<p>To install the GCC front end, do the following:</p>
<ol>
<li><tt>cd <i>where-you-want-the-front-end-to-live</i></tt></li>
- <li><tt>gunzip --stdout cfrontend-<i>version</i>.<i>platform</i>.tar.gz | tar -xvf
+ <li><tt>gunzip --stdout llvmgcc-<i>version</i>.<i>platform</i>.tar.gz | tar -xvf
-</tt></li>
</ol>
-<p>Next, you will need to fix your system header files:</p>
-
-<p><tt>cd cfrontend/<i>platform</i><br>
- ./fixheaders</tt></p>
+<p>Once the binary is uncompressed, you should add a symlink for llvm-gcc and
+llvm-g++ to some directory in your path. When you configure LLVM, it will
+automatically detect llvm-gcc's presence (if it is in your path) enabling its
+use in llvm-test. Note that you can always build or install llvm-gcc at any
+pointer after building the main LLVM repository: just reconfigure llvm and
+llvm-test will pick it up.
+</p>
<p>The binary versions of the GCC front end may not suit all of your needs. For
example, the binary distribution may include an old version of a system header
<p>In cases like these, you may want to try <a
href="CFEBuildInstrs.html">building the GCC front end from source.</a> This is
-not for the faint of heart, so be forewarned.</p>
+much easier now than it was in the past.</p>
</div>
documentation from the source code. This is disabled by default because
generating the documentation can take a long time and producess 100s of
megabytes of output.</dd>
+ <dt><i>--with-udis86</i></dt>
+ <dd>LLVM can use external disassembler library for various purposes (now it's
+ used only for examining code produced by JIT). This option will enable usage
+ of <a href="http://udis86.sourceforge.net/">udis86</a> x86 (both 32 and 64
+ bits) disassembler library.</dd>
</dl>
<p>To configure LLVM, follow these steps:</p>
LLVM assembly.</dd>
<dt><tt><b>llvm-ld</b></tt></dt>
- <dd><tt>llvm-ld</tt> is very similar to gccld and provides a general purpose
- and extensible linker for LLVM. This is the linker invoked by <tt>llvmc</tt>.
- It allows optimization modules to be loaded so that language specific
- optimizations can be applied at link time. This tool is considered
- experimental.</dd>
+ <dd><tt>llvm-ld</tt> is a general purpose and extensible linker for LLVM.
+ This is the linker invoked by <tt>llvmc</tt>. It performsn 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
the -march=c option).</dd>
<dt><tt><b>llvm-gcc</b></tt></dt>
- <dd><tt>llvm-gcc</tt> is a GCC-based C frontend
- that has been retargeted to emit LLVM code as the machine code output. It
- works just like any other GCC compiler, taking the typical <tt>-c, -S, -E,
- -o</tt> options that are typically used. The source code for the
- <tt>llvm-gcc</tt> tool is available as a separate CVS module.
- <blockquote>
- <dl>
- <dt><tt><b>gccas</b></tt></dt>
- <dd>This tool is invoked by the <tt>llvm-gcc</tt> frontend as the
- "assembler" part of the compiler. This tool actually assembles LLVM
- assembly to LLVM bytecode, performs a variety of optimizations, and
- outputs LLVM bytecode. Thus when you invoke
- <tt>llvm-gcc -c x.c -o x.o</tt>, you are causing <tt>gccas</tt> to be
- run, which writes the <tt>x.o</tt> file (which is an LLVM bytecode file
- that can be disassembled or manipulated just like any other bytecode
- file). The command line interface to <tt>gccas</tt> is designed to be
- as close as possible to the <b>system</b> `<tt>as</tt>' utility so that
- the gcc frontend itself did not have to be modified to interface to
- a "weird" assembler.</dd>
-
- <dt><tt><b>gccld</b></tt></dt>
- <dd><tt>gccld</tt> links together several LLVM bytecode files into one
- bytecode file and does some optimization. It is the linker invoked by
- the GCC frontend when multiple .o files need to be linked together.
- Like <tt>gccas</tt>, the command line interface of <tt>gccld</tt> is
- designed to match the system linker, to aid interfacing with the GCC
- frontend.</dd>
- </dl>
- </blockquote>
- </dd>
+ <dd><tt>llvm-gcc</tt> is a GCC-based C frontend that has been retargeted to
+ use LLVM as its backend instead of GCC's RTL backend. It can also emit LLVM
+ byte code or assembly (with the <tt>-emit-llvm</tt> option) instead of the
+ usual machine code output. It works just like any other GCC compiler,
+ taking the typical <tt>-c, -S, -E, -o</tt> options that are typically used.
+ Additionally, the the source code for <tt>llvm-gcc</tt> is available as a
+ separate CVS module.</dd>
<dt><tt><b>opt</b></tt></dt>
<dd><tt>opt</tt> reads LLVM bytecode, applies a series of LLVM to LLVM
directory, switch to directory <tt>llvm/tools/llc</tt> and build it,
causing a re-linking of LLC.<br><br>
- <dt><tt><b>NightlyTest.pl</b></tt> and
+ <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
<!-- *********************************************************************** -->
<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>This section gives an example of using LLVM. llvm-gcc3 is now obsolete,
+so we only include instructiosn for llvm-gcc4.
</p>
<p><b>Note:</b> The <i>gcc4</i> frontend's invocation is <b><i>considerably different</i></b>
</div>
-<!-- ======================================================================= -->
-<div class="doc_subsection"><a name="tutorial3">Example with llvm-gcc3</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 LLVM bytecode file:</p>
- <p><tt>% llvm-gcc hello.c -o hello</tt></p>
-
- <p>Note that you should have already built the tools and they have to be
- in your path, at least <tt>gccas</tt> and <tt>gccld</tt>.</p>
-
- <p>This will create two result files: <tt>hello</tt> and
- <tt>hello.bc</tt>. The <tt>hello.bc</tt> is the LLVM bytecode that
- corresponds the the compiled program and the library facilities that it
- required. <tt>hello</tt> is a simple shell script that runs the bytecode
- file with <tt>lli</tt>, making the result directly executable. Note that
- all LLVM optimizations are enabled by default, so there is no need for a
- "-O3" switch.</p></li>
-
- <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><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></li>
-
-</ol>
-
-</div>
<!-- *********************************************************************** -->
<div class="doc_section">
projects / oota-llvm.git / blobdiff