diff options
| author | alk3pInjection <webmaster@raspii.tech> | 2024-02-04 16:16:35 +0800 |
|---|---|---|
| committer | alk3pInjection <webmaster@raspii.tech> | 2024-02-04 16:16:35 +0800 |
| commit | abdaadbcae30fe0c9a66c7516798279fdfd97750 (patch) | |
| tree | 00a54a6e25601e43876d03c1a4a12a749d4a914c /share/doc/gcc/Alignment.html | |
https://developer.arm.com/downloads/-/arm-gnu-toolchain-downloads
Change-Id: I7303388733328cd98ab9aa3c30236db67f2e9e9c
Diffstat (limited to 'share/doc/gcc/Alignment.html')
| -rw-r--r-- | share/doc/gcc/Alignment.html | 122 |
1 files changed, 122 insertions, 0 deletions
diff --git a/share/doc/gcc/Alignment.html b/share/doc/gcc/Alignment.html new file mode 100644 index 0000000..4ace194 --- /dev/null +++ b/share/doc/gcc/Alignment.html @@ -0,0 +1,122 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> +<html> +<!-- This file documents the use of the GNU compilers. + +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>Using the GNU Compiler Collection (GCC): Alignment</title> + +<meta name="description" content="Using the GNU Compiler Collection (GCC): Alignment"> +<meta name="keywords" content="Using the GNU Compiler Collection (GCC): Alignment"> +<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="Indices.html#Indices" rel="index" title="Indices"> +<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents"> +<link href="C-Extensions.html#C-Extensions" rel="up" title="C Extensions"> +<link href="Inline.html#Inline" rel="next" title="Inline"> +<link href="Character-Escapes.html#Character-Escapes" rel="previous" title="Character Escapes"> +<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_US" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000"> +<a name="Alignment"></a> +<div class="header"> +<p> +Next: <a href="Inline.html#Inline" accesskey="n" rel="next">Inline</a>, Previous: <a href="Character-Escapes.html#Character-Escapes" accesskey="p" rel="previous">Character Escapes</a>, Up: <a href="C-Extensions.html#C-Extensions" accesskey="u" rel="up">C Extensions</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Indices.html#Indices" title="Index" rel="index">Index</a>]</p> +</div> +<hr> +<a name="Determining-the-Alignment-of-Functions_002c-Types-or-Variables"></a> +<h3 class="section">6.44 Determining the Alignment of Functions, Types or Variables</h3> +<a name="index-alignment"></a> +<a name="index-type-alignment"></a> +<a name="index-variable-alignment"></a> + +<p>The keyword <code>__alignof__</code> determines the alignment requirement of +a function, object, or a type, or the minimum alignment usually required +by a type. Its syntax is just like <code>sizeof</code> and C11 <code>_Alignof</code>. +</p> +<p>For example, if the target machine requires a <code>double</code> value to be +aligned on an 8-byte boundary, then <code>__alignof__ (double)</code> is 8. +This is true on many RISC machines. On more traditional machine +designs, <code>__alignof__ (double)</code> is 4 or even 2. +</p> +<p>Some machines never actually require alignment; they allow references to any +data type even at an odd address. For these machines, <code>__alignof__</code> +reports the smallest alignment that GCC gives the data type, usually as +mandated by the target ABI. +</p> +<p>If the operand of <code>__alignof__</code> is an lvalue rather than a type, +its value is the required alignment for its type, taking into account +any minimum alignment specified by attribute <code>aligned</code> +(see <a href="Common-Variable-Attributes.html#Common-Variable-Attributes">Common Variable Attributes</a>). For example, after this +declaration: +</p> +<div class="smallexample"> +<pre class="smallexample">struct foo { int x; char y; } foo1; +</pre></div> + +<p>the value of <code>__alignof__ (foo1.y)</code> is 1, even though its actual +alignment is probably 2 or 4, the same as <code>__alignof__ (int)</code>. +It is an error to ask for the alignment of an incomplete type other +than <code>void</code>. +</p> +<p>If the operand of the <code>__alignof__</code> expression is a function, +the expression evaluates to the alignment of the function which may +be specified by attribute <code>aligned</code> (see <a href="Common-Function-Attributes.html#Common-Function-Attributes">Common Function Attributes</a>). +</p> + + + +</body> +</html> |