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diff --git a/share/doc/gccint/Invoking-the-garbage-collector.html b/share/doc/gccint/Invoking-the-garbage-collector.html new file mode 100644 index 0000000..1280306 --- /dev/null +++ b/share/doc/gccint/Invoking-the-garbage-collector.html @@ -0,0 +1,111 @@ +<!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: Invoking the garbage collector</title> + +<meta name="description" content="GNU Compiler Collection (GCC) Internals: Invoking the garbage collector"> +<meta name="keywords" content="GNU Compiler Collection (GCC) Internals: Invoking the garbage collector"> +<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="Type-Information.html#Type-Information" rel="up" title="Type Information"> +<link href="Troubleshooting.html#Troubleshooting" rel="next" title="Troubleshooting"> +<link href="Files.html#Files" rel="previous" title="Files"> +<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="Invoking-the-garbage-collector"></a> +<div class="header"> +<p> +Next: <a href="Troubleshooting.html#Troubleshooting" accesskey="n" rel="next">Troubleshooting</a>, Previous: <a href="Files.html#Files" accesskey="p" rel="previous">Files</a>, Up: <a href="Type-Information.html#Type-Information" accesskey="u" rel="up">Type Information</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="How-to-invoke-the-garbage-collector"></a> +<h3 class="section">23.6 How to invoke the garbage collector</h3> +<a name="index-garbage-collector_002c-invocation"></a> +<a name="index-ggc_005fcollect"></a> + +<p>The GCC garbage collector GGC is only invoked explicitly. In contrast +with many other garbage collectors, it is not implicitly invoked by +allocation routines when a lot of memory has been consumed. So the +only way to have GGC reclaim storage is to call the <code>ggc_collect</code> +function explicitly. +With <var>mode</var> <code>GGC_COLLECT_FORCE</code> or otherwise (default +<code>GGC_COLLECT_HEURISTIC</code>) when the internal heuristic decides to +collect, this call is potentially an expensive operation, as it may +have to scan the entire heap. Beware that local variables (on the GCC +call stack) are not followed by such an invocation (as many other +garbage collectors do): you should reference all your data from static +or external <code>GTY</code>-ed variables, and it is advised to call +<code>ggc_collect</code> with a shallow call stack. The GGC is an exact mark +and sweep garbage collector (so it does not scan the call stack for +pointers). In practice GCC passes don’t often call <code>ggc_collect</code> +themselves, because it is called by the pass manager between passes. +</p> +<p>At the time of the <code>ggc_collect</code> call all pointers in the GC-marked +structures must be valid or <code>NULL</code>. In practice this means that +there should not be uninitialized pointer fields in the structures even +if your code never reads or writes those fields at a particular +instance. One way to ensure this is to use cleared versions of +allocators unless all the fields are initialized manually immediately +after allocation. +</p> + + + +</body> +</html> |