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82 lines
3.4 KiB
HTML
82 lines
3.4 KiB
HTML
4 years ago
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<title>Mode Iterators - GNU Compiler Collection (GCC) Internals</title>
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<meta http-equiv="Content-Type" content="text/html">
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<meta name="description" content="GNU Compiler Collection (GCC) Internals">
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<meta name="generator" content="makeinfo 4.13">
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<link title="Top" rel="start" href="index.html#Top">
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<link rel="up" href="Iterators.html#Iterators" title="Iterators">
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<link rel="next" href="Code-Iterators.html#Code-Iterators" title="Code Iterators">
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<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage">
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<!--
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Copyright (C) 1988-2015 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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funds for GNU development.-->
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--></style>
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</head>
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<body>
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<div class="node">
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<a name="Mode-Iterators"></a>
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<p>
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Next: <a rel="next" accesskey="n" href="Code-Iterators.html#Code-Iterators">Code Iterators</a>,
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Up: <a rel="up" accesskey="u" href="Iterators.html#Iterators">Iterators</a>
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<hr>
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</div>
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<h4 class="subsection">16.23.1 Mode Iterators</h4>
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<p><a name="index-mode-iterators-in-_0040file_007b_002emd_007d-files-3837"></a>
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Ports often need to define similar patterns for two or more different modes.
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For example:
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<ul>
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<li>If a processor has hardware support for both single and double
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floating-point arithmetic, the <code>SFmode</code> patterns tend to be
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very similar to the <code>DFmode</code> ones.
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<li>If a port uses <code>SImode</code> pointers in one configuration and
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<code>DImode</code> pointers in another, it will usually have very similar
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<code>SImode</code> and <code>DImode</code> patterns for manipulating pointers.
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</ul>
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<p>Mode iterators allow several patterns to be instantiated from one
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<samp><span class="file">.md</span></samp> file template. They can be used with any type of
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rtx-based construct, such as a <code>define_insn</code>,
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<code>define_split</code>, or <code>define_peephole2</code>.
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<ul class="menu">
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<li><a accesskey="1" href="Defining-Mode-Iterators.html#Defining-Mode-Iterators">Defining Mode Iterators</a>: Defining a new mode iterator.
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<li><a accesskey="2" href="Substitutions.html#Substitutions">Substitutions</a>: Combining mode iterators with substitutions
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<li><a accesskey="3" href="Examples.html#Examples">Examples</a>: Examples
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</ul>
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</body></html>
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