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<title>The GNU Fortran Compiler: OpenACC</title>

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<a name="OpenACC-1"></a>
<h4 class="subsection">6.1.17 OpenACC</h4>
<a name="index-OpenACC-1"></a>

<p>OpenACC is an application programming interface (API) that supports
offloading of code to accelerator devices.  It consists of a set of
compiler directives, library routines, and environment variables that
influence run-time behavior.
</p>
<p>GNU Fortran strives to be compatible to the
<a href="http://www.openacc.org/">OpenACC Application Programming
Interface v2.0</a>.
</p>
<p>To enable the processing of the OpenACC directive <code>!$acc</code> in
free-form source code; the <code>c$acc</code>, <code>*$acc</code> and <code>!$acc</code>
directives in fixed form; the <code>!$</code> conditional compilation
sentinels in free form; and the <code>c$</code>, <code>*$</code> and <code>!$</code>
sentinels in fixed form, <code>gfortran</code> needs to be invoked with
the <samp>-fopenacc</samp>.  This also arranges for automatic linking of
the GNU Offloading and Multi Processing Runtime Library
<a href="http://gcc.gnu.org/onlinedocs/libgomp/index.html#Top">libgomp</a> in <cite>GNU Offloading and Multi Processing Runtime
Library</cite>.
</p>
<p>The OpenACC Fortran runtime library routines are provided both in a
form of a Fortran 90 module named <code>openacc</code> and in a form of a
Fortran <code>include</code> file named <samp>openacc_lib.h</samp>.
</p>
<p>Note that this is an experimental feature, incomplete, and subject to
change in future versions of GCC.  See
<a href="https://gcc.gnu.org/wiki/OpenACC">https://gcc.gnu.org/wiki/OpenACC</a> for more information.
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