111 lines
4.9 KiB
HTML
111 lines
4.9 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>Using the GNU Compiler Collection (GCC): x86 Variable Attributes</title>
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<meta name="description" content="Using the GNU Compiler Collection (GCC): x86 Variable Attributes">
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<meta name="keywords" content="Using the GNU Compiler Collection (GCC): x86 Variable Attributes">
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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="Variable-Attributes.html#Variable-Attributes" rel="up" title="Variable Attributes">
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<link href="Xstormy16-Variable-Attributes.html#Xstormy16-Variable-Attributes" rel="next" title="Xstormy16 Variable Attributes">
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<link href="V850-Variable-Attributes.html#V850-Variable-Attributes" rel="prev" title="V850 Variable Attributes">
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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="x86-Variable-Attributes"></a>
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<div class="header">
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<p>
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Next: <a href="Xstormy16-Variable-Attributes.html#Xstormy16-Variable-Attributes" accesskey="n" rel="next">Xstormy16 Variable Attributes</a>, Previous: <a href="V850-Variable-Attributes.html#V850-Variable-Attributes" accesskey="p" rel="prev">V850 Variable Attributes</a>, Up: <a href="Variable-Attributes.html#Variable-Attributes" accesskey="u" rel="up">Variable Attributes</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="x86-Variable-Attributes-1"></a>
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<h4 class="subsection">6.32.14 x86 Variable Attributes</h4>
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<p>Two attributes are currently defined for x86 configurations:
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<code>ms_struct</code> and <code>gcc_struct</code>.
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</p>
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<dl compact="compact">
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<dt><code>ms_struct</code></dt>
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<dt><code>gcc_struct</code></dt>
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<dd><a name="index-ms_005fstruct-variable-attribute_002c-x86"></a>
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<a name="index-gcc_005fstruct-variable-attribute_002c-x86"></a>
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<p>If <code>packed</code> is used on a structure, or if bit-fields are used,
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it may be that the Microsoft ABI lays out the structure differently
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than the way GCC normally does. Particularly when moving packed
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data between functions compiled with GCC and the native Microsoft compiler
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(either via function call or as data in a file), it may be necessary to access
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either format.
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</p>
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<p>The <code>ms_struct</code> and <code>gcc_struct</code> attributes correspond
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to the <samp>-mms-bitfields</samp> and <samp>-mno-ms-bitfields</samp>
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command-line options, respectively;
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see <a href="x86-Options.html#x86-Options">x86 Options</a>, for details of how structure layout is affected.
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See <a href="x86-Type-Attributes.html#x86-Type-Attributes">x86 Type Attributes</a>, for information about the corresponding
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attributes on types.
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</p>
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</dd>
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</dl>
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</body>
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</html>
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