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| <!--*********************************************************************--> |
| <h1>OpenMP®: Support for the OpenMP language</h1> |
| <!--*********************************************************************--> |
| |
| <p>The OpenMP subproject of LLVM contains the |
| components required to build an executable 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 <tt>clang -fopenmp</tt> must be linked before it |
| can run. |
| </li> |
| <li> |
| the library that supports offload to target devices (in |
| "libomptarget") |
| </li> |
| </ul> |
| </p> |
| |
| <p>Support for the parts of the OpenMP 4.0 (and later) 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 "libomptarget" directory. |
| </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> |
| |
| <!--=====================================================================--> |
| <h2 id="dir-structure">Status</h2> |
| <!--=====================================================================--> |
| |
| <p>With the release of Clang 3.8.0, OpenMP 3.1 support is enabled in |
| Clang by default, and the OpenMP runtime is therefore built as a |
| normal part of the Clang build, and distributed with the binary |
| distributions.You do not, therefore, need explicitly to check out this code, or |
| build it out of tree; a normal Clang check out and build will |
| automatically include building these runtime libraries. |
| </p> |
| |
| <!--=====================================================================--> |
| <h2 id="goals">Features and Goals</h2> |
| <!--=====================================================================--> |
| |
| <ul> |
| <li>Support for the <a href="http://www.openmp.org/mp-documents/OpenMP3.1.pdf">OpenMP |
| 3.1 standard (PDF)</a> has been achieved in the Clang 3.8.0 |
| release. |
| </li> |
| |
| <li>Support for the |
| <a href="http://www.openmp.org/mp-documents/OpenMP4.0.0.pdf">OpenMP |
| 4.0 standard (PDF)</a> and <a href="http://www.openmp.org/mp-documents/OpenMP4.5.pdf">OpenMP |
| 4.5 standard (PDF)</a> is now being implemented. (Some OpenMP 4.0 |
| and 4.5 features are already available). |
| <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> |
| We currently have binary 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> |
| |
| <!--=====================================================================--> |
| <h2 id="why">Why have the runtime code here?</h2> |
| <!--=====================================================================--> |
| |
| <p>It makes sense to have the runtime sources in the same place |
| (and with the same license) as the compiler. |
| </p> |
| |
| <!--=====================================================================--> |
| <h2 id="requirements">Platform Support</h2> |
| <!--=====================================================================--> |
| |
| <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 OpenMP runtime is known to work on |
| <ul> |
| <li>ARM® architecture processors</li> |
| <li>PowerPC™ processors</li> |
| <li>32 and 64 bit X86 |
| processors when compiled with clang, with the Intel compiler |
| or with gcc, and also the Intel® Xeon Phi™ product family, when compiled with |
| the Intel compiler. |
| </li> |
| <li>MIPS and MIPS64</li> |
| </ul> |
| Ports to other architectures and operating systems are welcome. |
| </p> |
| |
| <p>A full OS and architecture compatibility matrix is in |
| <a href="README.txt">README.txt</a> |
| </p> |
| |
| |
| <!--=====================================================================--> |
| <h2>Get it and get involved!</h2> |
| <!--=====================================================================--> |
| |
| <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 && cd build</code></li> |
| <li><code>cmake path/to/llvm -DCMAKE_C_COMPILER=<C compiler> -DCMAKE_CXX_COMPILER=<C++ compiler></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</code></li> |
| <li><code>mkdir build && cd build</code></li> |
| <li><code>cmake path/to/openmp -DCMAKE_C_COMPILER=<C compiler> -DCMAKE_CXX_COMPILER=<C++ compiler></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 README.rst in the source code repository. |
| </p> |
| |
| <!--=====================================================================--> |
| <h3>Notes</h3> |
| <!--=====================================================================--> |
| |
| <p> |
| |
| </p> |
| |
| <p>Send discussions to the |
| (<a href="http://lists.llvm.org/mailman/listinfo/openmp-dev">OpenMP mailing list</a>).</p> |
| |
| |
| <!--=====================================================================--> |
| <h2>Design Documents</h2> |
| <!--=====================================================================--> |
| |
| <ul> |
| <li><a href="Reference.pdf">Runtime design (PDF)</a></li> |
| </ul> |
| |
| <!--=====================================================================--> |
| <h2>Copyright notices</h2> |
| <!--=====================================================================--> |
| <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> |
| <li> |
| MIPS is a trademark of MIPS Computer Systems in the U.S. and/or |
| other countries. |
| </li> |
| </ul> |
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