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| author | alk3pInjection <webmaster@raspii.tech> | 2024-02-04 16:16:35 +0800 |
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| committer | alk3pInjection <webmaster@raspii.tech> | 2024-02-04 16:16:35 +0800 |
| commit | abdaadbcae30fe0c9a66c7516798279fdfd97750 (patch) | |
| tree | 00a54a6e25601e43876d03c1a4a12a749d4a914c /share/doc/gfortran/OpenMP.html | |
https://developer.arm.com/downloads/-/arm-gnu-toolchain-downloads
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diff --git a/share/doc/gfortran/OpenMP.html b/share/doc/gfortran/OpenMP.html new file mode 100644 index 0000000..d4748c1 --- /dev/null +++ b/share/doc/gfortran/OpenMP.html @@ -0,0 +1,143 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> +<html> +<!-- Copyright (C) 1999-2023 Free Software Foundation, Inc. + +Permission is granted to copy, distribute and/or modify this document +under the terms of the GNU Free Documentation License, Version 1.3 or +any later version published by the Free Software Foundation; with the +Invariant Sections being "Funding Free Software", the Front-Cover +Texts being (a) (see below), and with the Back-Cover Texts being (b) +(see below). A copy of the license is included in the section entitled +"GNU Free Documentation License". + +(a) The FSF's Front-Cover Text is: + +A GNU Manual + +(b) The FSF's Back-Cover Text is: + +You have freedom to copy and modify this GNU Manual, like GNU + software. Copies published by the Free Software Foundation raise + funds for GNU development. --> +<!-- Created by GNU Texinfo 5.1, http://www.gnu.org/software/texinfo/ --> +<head> +<title>The GNU Fortran Compiler: OpenMP</title> + +<meta name="description" content="The GNU Fortran Compiler: OpenMP"> +<meta name="keywords" content="The GNU Fortran Compiler: OpenMP"> +<meta name="resource-type" content="document"> +<meta name="distribution" content="global"> +<meta name="Generator" content="makeinfo"> +<meta http-equiv="Content-Type" content="text/html; charset=utf-8"> +<link href="index.html#Top" rel="start" title="Top"> +<link href="Option-Index.html#Option-Index" rel="index" title="Option Index"> +<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents"> +<link href="Extensions-implemented-in-GNU-Fortran.html#Extensions-implemented-in-GNU-Fortran" rel="up" title="Extensions implemented in GNU Fortran"> +<link href="OpenACC.html#OpenACC" rel="next" title="OpenACC"> +<link href="CONVERT-specifier.html#CONVERT-specifier" rel="previous" title="CONVERT specifier"> +<style type="text/css"> +<!-- +a.summary-letter {text-decoration: none} +blockquote.smallquotation {font-size: smaller} +div.display {margin-left: 3.2em} +div.example {margin-left: 3.2em} +div.indentedblock {margin-left: 3.2em} +div.lisp {margin-left: 3.2em} +div.smalldisplay {margin-left: 3.2em} +div.smallexample {margin-left: 3.2em} +div.smallindentedblock {margin-left: 3.2em; font-size: smaller} +div.smalllisp {margin-left: 3.2em} +kbd {font-style:oblique} +pre.display {font-family: inherit} +pre.format {font-family: inherit} +pre.menu-comment {font-family: serif} +pre.menu-preformatted {font-family: serif} +pre.smalldisplay {font-family: inherit; font-size: smaller} +pre.smallexample {font-size: smaller} +pre.smallformat {font-family: inherit; font-size: smaller} +pre.smalllisp {font-size: smaller} +span.nocodebreak {white-space:nowrap} +span.nolinebreak {white-space:nowrap} +span.roman {font-family:serif; font-weight:normal} +span.sansserif {font-family:sans-serif; font-weight:normal} +ul.no-bullet {list-style: none} +--> +</style> + + +</head> + +<body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000"> +<a name="OpenMP"></a> +<div class="header"> +<p> +Next: <a href="OpenACC.html#OpenACC" accesskey="n" rel="next">OpenACC</a>, Previous: <a href="CONVERT-specifier.html#CONVERT-specifier" accesskey="p" rel="previous">CONVERT specifier</a>, Up: <a href="Extensions-implemented-in-GNU-Fortran.html#Extensions-implemented-in-GNU-Fortran" accesskey="u" rel="up">Extensions implemented in GNU Fortran</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Option-Index.html#Option-Index" title="Index" rel="index">Index</a>]</p> +</div> +<hr> +<a name="OpenMP-1"></a> +<h4 class="subsection">5.1.18 OpenMP</h4> +<a name="index-OpenMP-1"></a> + +<p>OpenMP (Open Multi-Processing) is an application programming +interface (API) that supports multi-platform shared memory +multiprocessing programming in C/C++ and Fortran on many +architectures, including Unix and Microsoft Windows platforms. +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="https://openmp.org/specifications/">OpenMP Application Program Interface v4.5</a>. +</p> +<p>To enable the processing of the OpenMP directive <code>!$omp</code> in +free-form source code; the <code>c$omp</code>, <code>*$omp</code> and <code>!$omp</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>-fopenmp</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 OpenMP Fortran runtime library routines are provided both in a +form of a Fortran 90 module named <code>omp_lib</code> and in a form of +a Fortran <code>include</code> file named <samp>omp_lib.h</samp>. +</p> +<p>An example of a parallelized loop taken from Appendix A.1 of +the OpenMP Application Program Interface v2.5: +</p><div class="smallexample"> +<pre class="smallexample">SUBROUTINE A1(N, A, B) + INTEGER I, N + REAL B(N), A(N) +!$OMP PARALLEL DO !I is private by default + DO I=2,N + B(I) = (A(I) + A(I-1)) / 2.0 + ENDDO +!$OMP END PARALLEL DO +END SUBROUTINE A1 +</pre></div> + +<p>Please note: +</p><ul> +<li> <samp>-fopenmp</samp> implies <samp>-frecursive</samp>, i.e., all local arrays +will be allocated on the stack. When porting existing code to OpenMP, +this may lead to surprising results, especially to segmentation faults +if the stacksize is limited. + +</li><li> On glibc-based systems, OpenMP enabled applications cannot be statically +linked due to limitations of the underlying pthreads-implementation. It +might be possible to get a working solution if +<code>-Wl,--whole-archive -lpthread -Wl,--no-whole-archive</code> is added +to the command line. However, this is not supported by <code>gcc</code> and +thus not recommended. +</li></ul> + +<hr> +<div class="header"> +<p> +Next: <a href="OpenACC.html#OpenACC" accesskey="n" rel="next">OpenACC</a>, Previous: <a href="CONVERT-specifier.html#CONVERT-specifier" accesskey="p" rel="previous">CONVERT specifier</a>, Up: <a href="Extensions-implemented-in-GNU-Fortran.html#Extensions-implemented-in-GNU-Fortran" accesskey="u" rel="up">Extensions implemented in GNU Fortran</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Option-Index.html#Option-Index" title="Index" rel="index">Index</a>]</p> +</div> + + + +</body> +</html> |