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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/Cleanups.html | |
https://developer.arm.com/downloads/-/arm-gnu-toolchain-downloads
Change-Id: I7303388733328cd98ab9aa3c30236db67f2e9e9c
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| -rw-r--r-- | share/doc/gccint/Cleanups.html | 135 |
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diff --git a/share/doc/gccint/Cleanups.html b/share/doc/gccint/Cleanups.html new file mode 100644 index 0000000..2e70bd7 --- /dev/null +++ b/share/doc/gccint/Cleanups.html @@ -0,0 +1,135 @@ +<!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: Cleanups</title> + +<meta name="description" content="GNU Compiler Collection (GCC) Internals: Cleanups"> +<meta name="keywords" content="GNU Compiler Collection (GCC) Internals: Cleanups"> +<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="OpenMP.html#OpenMP" rel="next" title="OpenMP"> +<link href="Jumps.html#Jumps" rel="previous" title="Jumps"> +<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="Cleanups"></a> +<div class="header"> +<p> +Next: <a href="OpenMP.html#OpenMP" accesskey="n" rel="next">OpenMP</a>, Previous: <a href="Jumps.html#Jumps" accesskey="p" rel="previous">Jumps</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="Cleanups-1"></a> +<h4 class="subsection">11.7.6 Cleanups</h4> +<a name="index-Cleanups"></a> + +<p>Destructors for local C++ objects and similar dynamic cleanups are +represented in GIMPLE by a <code>TRY_FINALLY_EXPR</code>. +<code>TRY_FINALLY_EXPR</code> has two operands, both of which are a sequence +of statements to execute. The first sequence is executed. When it +completes the second sequence is executed. +</p> +<p>The first sequence may complete in the following ways: +</p> +<ol> +<li> Execute the last statement in the sequence and fall off the +end. + +</li><li> Execute a goto statement (<code>GOTO_EXPR</code>) to an ordinary +label outside the sequence. + +</li><li> Execute a return statement (<code>RETURN_EXPR</code>). + +</li><li> Throw an exception. This is currently not explicitly represented in +GIMPLE. + +</li></ol> + +<p>The second sequence is not executed if the first sequence completes by +calling <code>setjmp</code> or <code>exit</code> or any other function that does +not return. The second sequence is also not executed if the first +sequence completes via a non-local goto or a computed goto (in general +the compiler does not know whether such a goto statement exits the +first sequence or not, so we assume that it doesn’t). +</p> +<p>After the second sequence is executed, if it completes normally by +falling off the end, execution continues wherever the first sequence +would have continued, by falling off the end, or doing a goto, etc. +</p> +<p>If the second sequence is an <code>EH_ELSE_EXPR</code> selector, then the +sequence in its first operand is used when the first sequence completes +normally, and that in its second operand is used for exceptional +cleanups, i.e., when an exception propagates out of the first sequence. +</p> +<p><code>TRY_FINALLY_EXPR</code> complicates the flow graph, since the cleanup +needs to appear on every edge out of the controlled block; this +reduces the freedom to move code across these edges. Therefore, the +EH lowering pass which runs before most of the optimization passes +eliminates these expressions by explicitly adding the cleanup to each +edge. Rethrowing the exception is represented using <code>RESX_EXPR</code>. +</p> +<hr> +<div class="header"> +<p> +Next: <a href="OpenMP.html#OpenMP" accesskey="n" rel="next">OpenMP</a>, Previous: <a href="Jumps.html#Jumps" accesskey="p" rel="previous">Jumps</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> |