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