1<html lang="en"> 2<head> 3<title>C99 Thread-Local Edits - Using the GNU Compiler Collection (GCC)</title> 4<meta http-equiv="Content-Type" content="text/html"> 5<meta name="description" content="Using the GNU Compiler Collection (GCC)"> 6<meta name="generator" content="makeinfo 4.13"> 7<link title="Top" rel="start" href="index.html#Top"> 8<link rel="up" href="Thread_002dLocal.html#Thread_002dLocal" title="Thread-Local"> 9<link rel="next" href="C_002b_002b98-Thread_002dLocal-Edits.html#C_002b_002b98-Thread_002dLocal-Edits" title="C++98 Thread-Local Edits"> 10<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage"> 11<!-- 12Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 131998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 142010 Free Software Foundation, Inc. 15 16Permission is granted to copy, distribute and/or modify this document 17under the terms of the GNU Free Documentation License, Version 1.3 or 18any later version published by the Free Software Foundation; with the 19Invariant Sections being ``Funding Free Software'', the Front-Cover 20Texts being (a) (see below), and with the Back-Cover Texts being (b) 21(see below). A copy of the license is included in the section entitled 22``GNU Free Documentation License''. 23 24(a) The FSF's Front-Cover Text is: 25 26 A GNU Manual 27 28(b) The FSF's Back-Cover Text is: 29 30 You have freedom to copy and modify this GNU Manual, like GNU 31 software. Copies published by the Free Software Foundation raise 32 funds for GNU development.--> 33<meta http-equiv="Content-Style-Type" content="text/css"> 34<style type="text/css"><!-- 35 pre.display { font-family:inherit } 36 pre.format { font-family:inherit } 37 pre.smalldisplay { font-family:inherit; font-size:smaller } 38 pre.smallformat { font-family:inherit; font-size:smaller } 39 pre.smallexample { font-size:smaller } 40 pre.smalllisp { font-size:smaller } 41 span.sc { font-variant:small-caps } 42 span.roman { font-family:serif; font-weight:normal; } 43 span.sansserif { font-family:sans-serif; font-weight:normal; } 44--></style> 45<link rel="stylesheet" type="text/css" href="../cs.css"> 46</head> 47<body> 48<div class="node"> 49<a name="C99-Thread-Local-Edits"></a> 50<a name="C99-Thread_002dLocal-Edits"></a> 51<p> 52Next: <a rel="next" accesskey="n" href="C_002b_002b98-Thread_002dLocal-Edits.html#C_002b_002b98-Thread_002dLocal-Edits">C++98 Thread-Local Edits</a>, 53Up: <a rel="up" accesskey="u" href="Thread_002dLocal.html#Thread_002dLocal">Thread-Local</a> 54<hr> 55</div> 56 57<h4 class="subsection">6.58.1 ISO/IEC 9899:1999 Edits for Thread-Local Storage</h4> 58 59<p>The following are a set of changes to ISO/IEC 9899:1999 (aka C99) 60that document the exact semantics of the language extension. 61 62 <ul> 63<li><cite>5.1.2 Execution environments</cite> 64 65 <p>Add new text after paragraph 1 66 67 <blockquote> 68Within either execution environment, a <dfn>thread</dfn> is a flow of 69control within a program. It is implementation defined whether 70or not there may be more than one thread associated with a program. 71It is implementation defined how threads beyond the first are 72created, the name and type of the function called at thread 73startup, and how threads may be terminated. However, objects 74with thread storage duration shall be initialized before thread 75startup. 76</blockquote> 77 78 <li><cite>6.2.4 Storage durations of objects</cite> 79 80 <p>Add new text before paragraph 3 81 82 <blockquote> 83An object whose identifier is declared with the storage-class 84specifier <code>__thread</code><!-- /@w --> has <dfn>thread storage duration</dfn>. 85Its lifetime is the entire execution of the thread, and its 86stored value is initialized only once, prior to thread startup. 87</blockquote> 88 89 <li><cite>6.4.1 Keywords</cite> 90 91 <p>Add <code>__thread</code>. 92 93 <li><cite>6.7.1 Storage-class specifiers</cite> 94 95 <p>Add <code>__thread</code> to the list of storage class specifiers in 96paragraph 1. 97 98 <p>Change paragraph 2 to 99 100 <blockquote> 101With the exception of <code>__thread</code>, at most one storage-class 102specifier may be given [<small class="dots">...</small>]. The <code>__thread</code> specifier may 103be used alone, or immediately following <code>extern</code> or 104<code>static</code>. 105</blockquote> 106 107 <p>Add new text after paragraph 6 108 109 <blockquote> 110The declaration of an identifier for a variable that has 111block scope that specifies <code>__thread</code> shall also 112specify either <code>extern</code> or <code>static</code>. 113 114 <p>The <code>__thread</code> specifier shall be used only with 115variables. 116</blockquote> 117 </ul> 118 119 </body></html> 120 121