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107 lines
4.2 KiB
HTML
107 lines
4.2 KiB
HTML
4 years ago
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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) 1988-2018 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 6.4, http://www.gnu.org/software/texinfo/ -->
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<head>
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<title>Conditional Expressions (GNU Compiler Collection (GCC) Internals)</title>
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<meta name="description" content="Conditional Expressions (GNU Compiler Collection (GCC) Internals)">
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<meta name="keywords" content="Conditional Expressions (GNU Compiler Collection (GCC) Internals)">
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<meta name="resource-type" content="document">
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<meta name="distribution" content="global">
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<meta name="Generator" content="makeinfo">
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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="Operands.html#Operands" rel="up" title="Operands">
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<link href="Logical-Operators.html#Logical-Operators" rel="next" title="Logical Operators">
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<link href="Compound-Lvalues.html#Compound-Lvalues" rel="prev" title="Compound Lvalues">
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<style type="text/css">
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a.summary-letter {text-decoration: none}
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div.example {margin-left: 3.2em}
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kbd {font-style: oblique}
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pre.display {font-family: inherit}
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pre.format {font-family: inherit}
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span.sansserif {font-family: sans-serif; font-weight: normal}
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ul.no-bullet {list-style: none}
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-->
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</style>
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</head>
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<body lang="en">
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<a name="Conditional-Expressions"></a>
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<div class="header">
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<p>
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Next: <a href="Logical-Operators.html#Logical-Operators" accesskey="n" rel="next">Logical Operators</a>, Previous: <a href="Compound-Lvalues.html#Compound-Lvalues" accesskey="p" rel="prev">Compound Lvalues</a>, Up: <a href="Operands.html#Operands" accesskey="u" rel="up">Operands</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="Conditional-Expressions-1"></a>
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<h4 class="subsection">12.6.3 Conditional Expressions</h4>
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<a name="index-Conditional-Expressions"></a>
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<p>A C <code>?:</code> expression is converted into an <code>if</code> statement with
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each branch assigning to the same temporary. So,
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</p>
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<div class="smallexample">
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<pre class="smallexample">a = b ? c : d;
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</pre></div>
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<p>becomes
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</p><div class="smallexample">
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<pre class="smallexample">if (b == 1)
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T1 = c;
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else
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T1 = d;
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a = T1;
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</pre></div>
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<p>The GIMPLE level if-conversion pass re-introduces <code>?:</code>
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expression, if appropriate. It is used to vectorize loops with
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conditions using vector conditional operations.
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</p>
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<p>Note that in GIMPLE, <code>if</code> statements are represented using
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<code>GIMPLE_COND</code>, as described below.
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</p>
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</body>
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</html>
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