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106 lines
4.4 KiB
HTML
106 lines
4.4 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>RTL Declarations (GNU Compiler Collection (GCC) Internals)</title>
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<meta name="description" content="RTL Declarations (GNU Compiler Collection (GCC) Internals)">
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<meta name="keywords" content="RTL Declarations (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="RTL.html#RTL" rel="up" title="RTL">
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<link href="Side-Effects.html#Side-Effects" rel="next" title="Side Effects">
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<link href="Conversions.html#Conversions" rel="prev" title="Conversions">
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<style type="text/css">
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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="RTL-Declarations"></a>
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<div class="header">
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<p>
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Next: <a href="Side-Effects.html#Side-Effects" accesskey="n" rel="next">Side Effects</a>, Previous: <a href="Conversions.html#Conversions" accesskey="p" rel="prev">Conversions</a>, Up: <a href="RTL.html#RTL" accesskey="u" rel="up">RTL</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="Declarations-2"></a>
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<h3 class="section">14.14 Declarations</h3>
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<a name="index-RTL-declarations"></a>
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<a name="index-declarations_002c-RTL"></a>
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<p>Declaration expression codes do not represent arithmetic operations
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but rather state assertions about their operands.
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</p>
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<dl compact="compact">
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<dd><a name="index-strict_005flow_005fpart"></a>
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<a name="index-subreg_002c-in-strict_005flow_005fpart"></a>
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</dd>
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<dt><code>(strict_low_part (subreg:<var>m</var> (reg:<var>n</var> <var>r</var>) 0))</code></dt>
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<dd><p>This expression code is used in only one context: as the destination operand of a
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<code>set</code> expression. In addition, the operand of this expression
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must be a non-paradoxical <code>subreg</code> expression.
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</p>
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<p>The presence of <code>strict_low_part</code> says that the part of the
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register which is meaningful in mode <var>n</var>, but is not part of
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mode <var>m</var>, is not to be altered. Normally, an assignment to such
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a subreg is allowed to have undefined effects on the rest of the
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register when <var>m</var> is smaller than ‘<samp>REGMODE_NATURAL_SIZE (<var>n</var>)</samp>’.
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</p></dd>
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</dl>
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</body>
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</html>
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