114 lines
5.3 KiB
HTML
114 lines
5.3 KiB
HTML
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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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<html>
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<!-- Copyright (C) 1988-2016 Free Software Foundation, Inc.
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Permission is granted to copy, distribute and/or modify this document
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under the terms of the GNU Free Documentation License, Version 1.3 or
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any later version published by the Free Software Foundation; with the
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Invariant Sections being "Funding Free Software", the Front-Cover
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Texts being (a) (see below), and with the Back-Cover Texts being (b)
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(see below). A copy of the license is included in the section entitled
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"GNU Free Documentation License".
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(a) The FSF's Front-Cover Text is:
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A GNU Manual
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(b) The FSF's Back-Cover Text is:
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You have freedom to copy and modify this GNU Manual, like GNU
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software. Copies published by the Free Software Foundation raise
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funds for GNU development. -->
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<!-- Created by GNU Texinfo 5.2, http://www.gnu.org/software/texinfo/ -->
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<head>
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<title>GNU Compiler Collection (GCC) Internals: Plugins GC</title>
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<meta name="description" content="GNU Compiler Collection (GCC) Internals: Plugins GC">
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<meta name="keywords" content="GNU Compiler Collection (GCC) Internals: Plugins GC">
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<meta name="resource-type" content="document">
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<meta name="distribution" content="global">
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<meta name="Generator" content="makeinfo">
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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<link href="index.html#Top" rel="start" title="Top">
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<link href="Option-Index.html#Option-Index" rel="index" title="Option Index">
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<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
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<link href="Plugins.html#Plugins" rel="up" title="Plugins">
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<link href="Plugins-description.html#Plugins-description" rel="next" title="Plugins description">
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<link href="Plugins-pass.html#Plugins-pass" rel="prev" title="Plugins pass">
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<style type="text/css">
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<!--
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a.summary-letter {text-decoration: none}
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kbd {font-style:oblique}
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pre.display {font-family: inherit}
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pre.format {font-family: inherit}
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pre.smalllisp {font-size: smaller}
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span.nocodebreak {white-space:nowrap}
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span.nolinebreak {white-space:nowrap}
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span.roman {font-family:serif; font-weight:normal}
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span.sansserif {font-family:sans-serif; font-weight:normal}
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ul.no-bullet {list-style: none}
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-->
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</style>
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</head>
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<body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000">
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<a name="Plugins-GC"></a>
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<div class="header">
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<p>
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Next: <a href="Plugins-description.html#Plugins-description" accesskey="n" rel="next">Plugins description</a>, Previous: <a href="Plugins-pass.html#Plugins-pass" accesskey="p" rel="prev">Plugins pass</a>, Up: <a href="Plugins.html#Plugins" accesskey="u" rel="up">Plugins</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>
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</div>
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<hr>
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<a name="Interacting-with-the-GCC-Garbage-Collector"></a>
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<h3 class="section">23.4 Interacting with the GCC Garbage Collector</h3>
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<p>Some plugins may want to be informed when GGC (the GCC Garbage
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Collector) is running. They can register callbacks for the
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<code>PLUGIN_GGC_START</code> and <code>PLUGIN_GGC_END</code> events (for which
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the callback is called with a null <code>gcc_data</code>) to be notified of
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the start or end of the GCC garbage collection.
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</p>
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<p>Some plugins may need to have GGC mark additional data. This can be
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done by registering a callback (called with a null <code>gcc_data</code>)
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for the <code>PLUGIN_GGC_MARKING</code> event. Such callbacks can call the
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<code>ggc_set_mark</code> routine, preferably through the <code>ggc_mark</code> macro
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(and conversely, these routines should usually not be used in plugins
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outside of the <code>PLUGIN_GGC_MARKING</code> event). Plugins that wish to hold
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weak references to gc data may also use this event to drop weak references when
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the object is about to be collected. The <code>ggc_marked_p</code> function can be
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used to tell if an object is marked, or is about to be collected. The
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<code>gt_clear_cache</code> overloads which some types define may also be of use in
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managing weak references.
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</p>
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<p>Some plugins may need to add extra GGC root tables, e.g. to handle their own
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<code>GTY</code>-ed data. This can be done with the <code>PLUGIN_REGISTER_GGC_ROOTS</code>
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pseudo-event with a null callback and the extra root table (of type <code>struct
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ggc_root_tab*</code>) as <code>user_data</code>. Running the
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<code>gengtype -p <var>source-dir</var> <var>file-list</var> <var>plugin*.c</var> ...</code>
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utility generates these extra root tables.
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</p>
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<p>You should understand the details of memory management inside GCC
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before using <code>PLUGIN_GGC_MARKING</code> or <code>PLUGIN_REGISTER_GGC_ROOTS</code>.
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</p>
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</body>
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</html>
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