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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/gccint/OpenMP.html | |
https://developer.arm.com/downloads/-/arm-gnu-toolchain-downloads
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diff --git a/share/doc/gccint/OpenMP.html b/share/doc/gccint/OpenMP.html new file mode 100644 index 0000000..4edb113 --- /dev/null +++ b/share/doc/gccint/OpenMP.html @@ -0,0 +1,321 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> +<html> +<!-- Copyright (C) 1988-2023 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>GNU Compiler Collection (GCC) Internals: OpenMP</title> + +<meta name="description" content="GNU Compiler Collection (GCC) Internals: OpenMP"> +<meta name="keywords" content="GNU Compiler Collection (GCC) Internals: 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="Statements.html#Statements" rel="up" title="Statements"> +<link href="OpenACC.html#OpenACC" rel="next" title="OpenACC"> +<link href="Cleanups.html#Cleanups" rel="previous" title="Cleanups"> +<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="Cleanups.html#Cleanups" accesskey="p" rel="previous">Cleanups</a>, Up: <a href="Statements.html#Statements" accesskey="u" rel="up">Statements</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">11.7.7 OpenMP</h4> +<a name="index-OMP_005fPARALLEL"></a> +<a name="index-OMP_005fFOR"></a> +<a name="index-OMP_005fSIMD"></a> +<a name="index-OMP_005fDISTRIBUTE"></a> +<a name="index-OMP_005fTASKLOOP"></a> +<a name="index-OMP_005fLOOP"></a> +<a name="index-OMP_005fSECTIONS"></a> +<a name="index-OMP_005fSINGLE"></a> +<a name="index-OMP_005fSECTION"></a> +<a name="index-OMP_005fMASTER"></a> +<a name="index-OMP_005fORDERED"></a> +<a name="index-OMP_005fCRITICAL"></a> +<a name="index-OMP_005fRETURN"></a> +<a name="index-OMP_005fCONTINUE"></a> +<a name="index-OMP_005fATOMIC"></a> +<a name="index-OMP_005fCLAUSE"></a> + +<p>All the statements starting with <code>OMP_</code> represent directives and +clauses used by the OpenMP API <a href="https://www.openmp.org">https://www.openmp.org</a><!-- /@w -->. +</p> +<dl compact="compact"> +<dt><code>OMP_PARALLEL</code></dt> +<dd> +<p>Represents <code>#pragma omp parallel [clause1 … clauseN]</code>. It +has four operands: +</p> +<p>Operand <code>OMP_PARALLEL_BODY</code> is valid while in GENERIC and +High GIMPLE forms. It contains the body of code to be executed +by all the threads. During GIMPLE lowering, this operand becomes +<code>NULL</code> and the body is emitted linearly after +<code>OMP_PARALLEL</code>. +</p> +<p>Operand <code>OMP_PARALLEL_CLAUSES</code> is the list of clauses +associated with the directive. +</p> +<p>Operand <code>OMP_PARALLEL_FN</code> is created by +<code>pass_lower_omp</code>, it contains the <code>FUNCTION_DECL</code> +for the function that will contain the body of the parallel +region. +</p> +<p>Operand <code>OMP_PARALLEL_DATA_ARG</code> is also created by +<code>pass_lower_omp</code>. If there are shared variables to be +communicated to the children threads, this operand will contain +the <code>VAR_DECL</code> that contains all the shared values and +variables. +</p> +</dd> +<dt><code>OMP_FOR</code></dt> +<dt><code>OMP_SIMD</code></dt> +<dt><code>OMP_DISTRIBUTE</code></dt> +<dt><code>OMP_TASKLOOP</code></dt> +<dt><code>OMP_LOOP</code></dt> +<dd> +<p>Represents <code>#pragma omp for [clause1 … clauseN]</code> and +related loop constructs (respectively). +</p> +<p>A single <code>OMP_FOR</code> node represents an entire nest of collapsed +loops; as noted below, some of its arguments are vectors of length +equal to the collapse depth, and the corresponding elements holding +data specific to a particular loop in the nest. These vectors are +numbered from the outside in so that the outermost loop is element 0. +</p> +<p>These constructs have seven operands: +</p> +<p>Operand <code>OMP_FOR_BODY</code> contains the loop body. +</p> +<p>Operand <code>OMP_FOR_CLAUSES</code> is the list of clauses +associated with the directive. +</p> +<p>Operand <code>OMP_FOR_INIT</code> is a vector containing iteration +variable initializations of the form <code>VAR = N1</code>. +</p> +<p>Operand <code>OMP_FOR_COND</code> is vector containing loop +conditional expressions of the form <code>VAR {<,>,<=,>=} N2</code>. +</p> +<p>Operand <code>OMP_FOR_INCR</code> is a vector containing loop index +increment expressions of the form <code>VAR {+=,-=} INCR</code>. +</p> +<p>Operand <code>OMP_FOR_PRE_BODY</code> contains side effect code from +operands <code>OMP_FOR_INIT</code>, <code>OMP_FOR_COND</code> and +<code>OMP_FOR_INCR</code>. These side effects are part of the +<code>OMP_FOR</code> block but must be evaluated before the start of +loop body. <code>OMP_FOR_PRE_BODY</code> specifically +includes <code>DECL_EXPR</code>s for iteration variables that are +declared in the nested <code>for</code> loops. +Note this field is not a vector; it may be null, but otherwise is +usually a statement list collecting the side effect code from all +the collapsed loops. +</p> +<p>Operand <code>OMP_FOR_ORIG_DECLS</code> holds <code>VAR_DECLS</code> for the +original user-specified iterator variables in the source code. +In some cases, like C++ class iterators or range <code>for</code> with +decomposition, the <code>for</code> loop is rewritten by the front end to +use a temporary iteration variable. The purpose of this field is to +make the original variables available to the gimplifier so it can +adjust their data-sharing attributes and diagnose errors. +<code>OMP_FOR_ORIG_DECLS</code> is a vector field, with each element holding +a list of <code>VAR_DECLS</code> for the corresponding collapse level. +</p> +<p>The loop index variable <code>VAR</code> must be a signed integer variable, +which is implicitly private to each thread. For rectangular loops, +the bounds <code>N1</code> and <code>N2</code> and the increment expression +<code>INCR</code> are required to be loop-invariant integer expressions +that are evaluated without any synchronization. The evaluation order, +frequency of evaluation and side effects are otherwise unspecified +by the standard. +</p> +<p>For non-rectangular loops, in which the bounds of an inner loop depend +on the index of an outer loop, the bit <code>OMP_FOR_NON_RECTANGULAR</code> +must be set. In this case <code>N1</code> and <code>N2</code> are not ordinary +expressions, but instead a <code>TREE_VEC</code> with three elements: +the <code>DECL</code> for the outer loop variable, a multiplication +factor, and an offset. +</p> +</dd> +<dt><code>OMP_SECTIONS</code></dt> +<dd> +<p>Represents <code>#pragma omp sections [clause1 … clauseN]</code>. +</p> +<p>Operand <code>OMP_SECTIONS_BODY</code> contains the sections body, +which in turn contains a set of <code>OMP_SECTION</code> nodes for +each of the concurrent sections delimited by <code>#pragma omp +section</code>. +</p> +<p>Operand <code>OMP_SECTIONS_CLAUSES</code> is the list of clauses +associated with the directive. +</p> +</dd> +<dt><code>OMP_SECTION</code></dt> +<dd> +<p>Section delimiter for <code>OMP_SECTIONS</code>. +</p> +</dd> +<dt><code>OMP_SINGLE</code></dt> +<dd> +<p>Represents <code>#pragma omp single</code>. +</p> +<p>Operand <code>OMP_SINGLE_BODY</code> contains the body of code to be +executed by a single thread. +</p> +<p>Operand <code>OMP_SINGLE_CLAUSES</code> is the list of clauses +associated with the directive. +</p> +</dd> +<dt><code>OMP_MASTER</code></dt> +<dd> +<p>Represents <code>#pragma omp master</code>. +</p> +<p>Operand <code>OMP_MASTER_BODY</code> contains the body of code to be +executed by the master thread. +</p> +</dd> +<dt><code>OMP_ORDERED</code></dt> +<dd> +<p>Represents <code>#pragma omp ordered</code>. +</p> +<p>Operand <code>OMP_ORDERED_BODY</code> contains the body of code to be +executed in the sequential order dictated by the loop index +variable. +</p> +</dd> +<dt><code>OMP_CRITICAL</code></dt> +<dd> +<p>Represents <code>#pragma omp critical [name]</code>. +</p> +<p>Operand <code>OMP_CRITICAL_BODY</code> is the critical section. +</p> +<p>Operand <code>OMP_CRITICAL_NAME</code> is an optional identifier to +label the critical section. +</p> +</dd> +<dt><code>OMP_RETURN</code></dt> +<dd> +<p>This does not represent any OpenMP directive, it is an artificial +marker to indicate the end of the body of an OpenMP. It is used +by the flow graph (<code>tree-cfg.cc</code>) and OpenMP region +building code (<code>omp-low.cc</code>). +</p> +</dd> +<dt><code>OMP_CONTINUE</code></dt> +<dd> +<p>Similarly, this instruction does not represent an OpenMP +directive, it is used by <code>OMP_FOR</code> (and similar codes) as well as +<code>OMP_SECTIONS</code> to mark the place where the code needs to +loop to the next iteration, or the next section, respectively. +</p> +<p>In some cases, <code>OMP_CONTINUE</code> is placed right before +<code>OMP_RETURN</code>. But if there are cleanups that need to +occur right after the looping body, it will be emitted between +<code>OMP_CONTINUE</code> and <code>OMP_RETURN</code>. +</p> +</dd> +<dt><code>OMP_ATOMIC</code></dt> +<dd> +<p>Represents <code>#pragma omp atomic</code>. +</p> +<p>Operand 0 is the address at which the atomic operation is to be +performed. +</p> +<p>Operand 1 is the expression to evaluate. The gimplifier tries +three alternative code generation strategies. Whenever possible, +an atomic update built-in is used. If that fails, a +compare-and-swap loop is attempted. If that also fails, a +regular critical section around the expression is used. +</p> +</dd> +<dt><code>OMP_CLAUSE</code></dt> +<dd> +<p>Represents clauses associated with one of the <code>OMP_</code> directives. +Clauses are represented by separate subcodes defined in +<samp>tree.h</samp>. Clauses codes can be one of: +<code>OMP_CLAUSE_PRIVATE</code>, <code>OMP_CLAUSE_SHARED</code>, +<code>OMP_CLAUSE_FIRSTPRIVATE</code>, +<code>OMP_CLAUSE_LASTPRIVATE</code>, <code>OMP_CLAUSE_COPYIN</code>, +<code>OMP_CLAUSE_COPYPRIVATE</code>, <code>OMP_CLAUSE_IF</code>, +<code>OMP_CLAUSE_NUM_THREADS</code>, <code>OMP_CLAUSE_SCHEDULE</code>, +<code>OMP_CLAUSE_NOWAIT</code>, <code>OMP_CLAUSE_ORDERED</code>, +<code>OMP_CLAUSE_DEFAULT</code>, <code>OMP_CLAUSE_REDUCTION</code>, +<code>OMP_CLAUSE_COLLAPSE</code>, <code>OMP_CLAUSE_UNTIED</code>, +<code>OMP_CLAUSE_FINAL</code>, and <code>OMP_CLAUSE_MERGEABLE</code>. Each code +represents the corresponding OpenMP clause. +</p> +<p>Clauses associated with the same directive are chained together +via <code>OMP_CLAUSE_CHAIN</code>. Those clauses that accept a list +of variables are restricted to exactly one, accessed with +<code>OMP_CLAUSE_VAR</code>. Therefore, multiple variables under the +same clause <code>C</code> need to be represented as multiple <code>C</code> clauses +chained together. This facilitates adding new clauses during +compilation. +</p> +</dd> +</dl> + +<hr> +<div class="header"> +<p> +Next: <a href="OpenACC.html#OpenACC" accesskey="n" rel="next">OpenACC</a>, Previous: <a href="Cleanups.html#Cleanups" accesskey="p" rel="previous">Cleanups</a>, Up: <a href="Statements.html#Statements" accesskey="u" rel="up">Statements</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> |