111 lines
4.9 KiB
HTML
111 lines
4.9 KiB
HTML
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<title>Using the GNU Compiler Collection (GCC): x86 Variable Attributes</title>
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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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<a name="x86-Variable-Attributes"></a>
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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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<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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