99 lines
4.9 KiB
HTML
99 lines
4.9 KiB
HTML
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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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<!-- This file documents the GNU Assembler "as".
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Copyright (C) 1991-2016 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
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or any later version published by the Free Software Foundation;
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with no Invariant Sections, with no Front-Cover Texts, and with no
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Back-Cover Texts. A copy of the license is included in the
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section entitled "GNU Free Documentation License".
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<!-- Created by GNU Texinfo 5.2, http://www.gnu.org/software/texinfo/ -->
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<head>
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<title>Using as: Xtensa Relaxation</title>
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<meta name="description" content="Using as: Xtensa Relaxation">
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<link href="index.html#Top" rel="start" title="Top">
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<link href="AS-Index.html#AS-Index" rel="index" title="AS Index">
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<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
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<link href="Xtensa_002dDependent.html#Xtensa_002dDependent" rel="up" title="Xtensa-Dependent">
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<link href="Xtensa-Branch-Relaxation.html#Xtensa-Branch-Relaxation" rel="next" title="Xtensa Branch Relaxation">
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<link href="Xtensa-Automatic-Alignment.html#Xtensa-Automatic-Alignment" rel="prev" title="Xtensa Automatic Alignment">
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<body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000">
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<a name="Xtensa-Relaxation"></a>
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<div class="header">
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<p>
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Next: <a href="Xtensa-Directives.html#Xtensa-Directives" accesskey="n" rel="next">Xtensa Directives</a>, Previous: <a href="Xtensa-Optimizations.html#Xtensa-Optimizations" accesskey="p" rel="prev">Xtensa Optimizations</a>, Up: <a href="Xtensa_002dDependent.html#Xtensa_002dDependent" accesskey="u" rel="up">Xtensa-Dependent</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="AS-Index.html#AS-Index" title="Index" rel="index">Index</a>]</p>
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</div>
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<hr>
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<a name="Xtensa-Relaxation-1"></a>
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<h4 class="subsection">9.52.4 Xtensa Relaxation</h4>
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<a name="index-relaxation"></a>
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<p>When an instruction operand is outside the range allowed for that
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particular instruction field, <code>as</code> can transform the code
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to use a functionally-equivalent instruction or sequence of
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instructions. This process is known as <em>relaxation</em>. This is
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typically done for branch instructions because the distance of the
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branch targets is not known until assembly-time. The Xtensa assembler
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offers branch relaxation and also extends this concept to function
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calls, <code>MOVI</code> instructions and other instructions with immediate
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fields.
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</p>
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<table class="menu" border="0" cellspacing="0">
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<tr><td align="left" valign="top">• <a href="Xtensa-Branch-Relaxation.html#Xtensa-Branch-Relaxation" accesskey="1">Xtensa Branch Relaxation</a>:</td><td> </td><td align="left" valign="top">Relaxation of Branches.
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</td></tr>
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<tr><td align="left" valign="top">• <a href="Xtensa-Call-Relaxation.html#Xtensa-Call-Relaxation" accesskey="2">Xtensa Call Relaxation</a>:</td><td> </td><td align="left" valign="top">Relaxation of Function Calls.
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</td></tr>
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<tr><td align="left" valign="top">• <a href="Xtensa-Jump-Relaxation.html#Xtensa-Jump-Relaxation" accesskey="3">Xtensa Jump Relaxation</a>:</td><td> </td><td align="left" valign="top">Relaxation of Jumps.
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</td></tr>
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<tr><td align="left" valign="top">• <a href="Xtensa-Immediate-Relaxation.html#Xtensa-Immediate-Relaxation" accesskey="4">Xtensa Immediate Relaxation</a>:</td><td> </td><td align="left" valign="top">Relaxation of other Immediate Fields.
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</td></tr>
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</table>
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</body>
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</html>
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