llvm-project/openmp/www/index.html

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<a href="http://llvm.org/">LLVM Home</a>
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<label>OpenMP Info</label>
<a href="/index.html">About</a>
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<label>Quick Links</label>
<a href="http://lists.llvm.org/mailman/listinfo/openmp-dev">openmp-dev</a>
<a href="http://lists.llvm.org/mailman/listinfo/openmp-commits">openmp-commits</a>
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<h1>OpenMP&reg;: Support for the OpenMP language</h1>
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<p>The OpenMP subproject of LLVM is intended to contain all of the
components required to build an executing OpenMP program that are
outside the compiler itself.
</p>
<p>Here you can find :-
<ul>
<li>
the code for the runtime library against which
code compiled by the OpenMP/Clang compiler must be linked before it
can run. This code is also available
at <a href="http://openmprtl.org/">openmprtl.org</a>; we intend to
keep the different sites in sync.
</li>
<li>
the library that supports offload to target devices (in
"offload")
</li>
<li>
the OpenUH test-suite which is being integrated.
</li>
</ul>
</p>
<p>Support for the parts of the OpenMP 4.0 language that are not
associated with the "target" constructs are contained in the
"runtime" directory. Support for offloading computation via the
"target" directive is in the separate "offload" directory. That
builds a library that provides the interfaces for transferring code
and data to an attached computational device. Initial support here
is for the Intel&reg Xeon Phi&#0153 coprocessor, but work is
beginning to support other attached computing devices, and the
design is intended to be general. The README.txt in the "offload"
directory describes how to build the offload library.
</p>
<p>All of the code here is <a
href="http://llvm.org/docs/DeveloperPolicy.html#license">dual licensed</a>
under the MIT license and the UIUC License (a BSD-like license).
The LICENSE.txt file at the top of the OpenMP project contains
the license text and associated patent grants.
</p>
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<h2 id="goals">Features and Goals</h2>
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<ul>
<li>Correctness as defined by the
<a href="http://www.openmp.org/mp-documents/OpenMP3.1.pdf">OpenMP
3.1 standard (PDF)</a> now, and <a href="http://www.openmp.org/mp-documents/OpenMP4.0.0.pdf">OpenMP
4.0 standard (PDF)</a> in the future.</li>
<li>High performance.</li>
<li>ABI compatibility with <a href="http://gcc.gnu.org">Gcc</a> and
<a href="http://software.intel.com/en-us/intel-compilers">Intel's
existing OpenMP compilers.</a>
With this release we have restored compatibility with OpenMP
3.1 code compiled by gcc 4.9, however we do not have support
for OpenMP 4.0 code that uses task cancellation when compiled
by gcc 4.9. How we will support such code remains a research issue.
</li>
</ul>
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<h2 id="why">Why have the runtime code here?</h2>
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<p>It makes sense to have the runtime sources in the same place
(and with the same license) as the compiler.
</p>
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<h2 id="requirements">Platform Support</h2>
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<p>The OpenMP runtime is known to work on
<ul>
<li>ARM&reg;&nbsp; architecture processors</li>
<li>PowerPC&trade;&nbsp; processors</li>
<li>32 and 64 bit X86
processors when compiled with clang, with the Intel compiler
or with gcc, and also the Intel&reg;&nbsp;Xeon Phi&trade; product family, when compiled with
the Intel compiler.
</li>
</ul>
Ports to other architectures and operating systems are welcome.
</p>
<p>A full OS and archiecture compatibility matrix is in
<a href="README.txt">README.txt</a>
</p>
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<h2 id="dir-structure">Status</h2>
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<p>The runtime can be built with gcc, icc or clang. However, note
that a runtime built with clang cannot be guaranteed to work with
OpenMP code compiled by the other compilers, since clang does not support
a 128-bit float type, and cannot therefore generate the code used
for reductions of that type (which may occur in user code compiled
by the other compilers).
</p>
<p>The University of Houston has kindly contributed their test
suite (in the "testsuite" directory). Integration and use of this
for automatic testing is in progress.
</p>
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<h2>Get it and get involved!</h2>
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<p>First please review our
<a href="http://llvm.org/docs/DeveloperPolicy.html">Developer's Policy</a>.
<p>To check out the code, use:</p>
<ul>
<li><code>svn co http://llvm.org/svn/llvm-project/openmp/trunk openmp</code></li>
</ul>
<p>
Note that for an in-tree build, you should check out openmp to llvm/projects.
</p>
<p>In-tree build:</p>
<ul>
<li><code>cd where-you-want-to-live</code></li>
<li>Check out openmp into llvm/projects</li>
<li><code>cd where-you-want-to-build</code></li>
<li><code>mkdir build &amp;&amp; cd build</code></li>
<li><code>cmake path/to/llvm -DCMAKE_C_COMPILER=&lt;C compiler&gt; -DCMAKE_CXX_COMPILER=&lt;C++ compiler&gt;</code></li>
<li><code>make omp</code></li>
</ul>
<p>Out-of-tree build:</p>
<ul>
<li><code>cd where-you-want-to-live</code></li>
<li>Check out openmp</li>
<li><code>cd where-you-want-to-live/openmp/runtime</code></li>
<li><code>mkdir build &amp;&amp; cd build</code></li>
<li><code>cmake path/to/openmp -DCMAKE_C_COMPILER=&lt;C compiler&gt; -DCMAKE_CXX_COMPILER=&lt;C++ compiler&gt;</code></li>
<li><code>make</code></li>
</ul>
<p>Full details of how to build are in the
<a href="README.txt">README.txt</a> and Build_With_CMake.txt (inside the runtime/ subdirectory)
</p>
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<h3>Notes</h3>
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<p>
</p>
<p>Send discussions to the
(<a href="http://lists.llvm.org/mailman/listinfo/openmp-dev">OpenMP mailing list</a>).</p>
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<h2>Design Documents</h2>
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<ul>
<li><a href="Reference.pdf">Runtime design (PDF)</a></li>
</ul>
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<h2>Copyright notices</h2>
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<ul>
<li>
The OpenMP name and the OpenMP logo are registered trademarks of the
OpenMP Architecture Review Board.
</li>
<li>
Intel is a trademark of Intel Corporation in the U.S. and/or other
countries.
</li>
<li>
PowerPC is a trademark of IBM Corporation in the U.S. and/or other
countries.
</li>
<li>
ARM is a trademark of ARM Corporation in the U.S. and/or
other countries.
</li>
</ul>
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