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68 lines
3.2 KiB
HTML
68 lines
3.2 KiB
HTML
15 years ago
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<title>Xtensa Relaxation - Using as</title>
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<meta name="description" content="Using as">
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<link title="Top" rel="start" href="index.html#Top">
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<link rel="up" href="Xtensa_002dDependent.html#Xtensa_002dDependent" title="Xtensa-Dependent">
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<link rel="prev" href="Xtensa-Optimizations.html#Xtensa-Optimizations" title="Xtensa Optimizations">
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<link rel="next" href="Xtensa-Directives.html#Xtensa-Directives" title="Xtensa Directives">
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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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This file documents the GNU Assembler "as".
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Copyright (C) 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000, 2001, 2002,
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2006, 2007 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 1.1
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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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--></style>
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</head>
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<body>
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<div class="node">
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<p>
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<a name="Xtensa-Relaxation"></a>Next: <a rel="next" accesskey="n" href="Xtensa-Directives.html#Xtensa-Directives">Xtensa Directives</a>,
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Previous: <a rel="previous" accesskey="p" href="Xtensa-Optimizations.html#Xtensa-Optimizations">Xtensa Optimizations</a>,
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Up: <a rel="up" accesskey="u" href="Xtensa_002dDependent.html#Xtensa_002dDependent">Xtensa-Dependent</a>
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<hr><br>
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</div>
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<h4 class="subsection">9.36.4 Xtensa Relaxation</h4>
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<p><a name="index-relaxation-1863"></a>
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When an instruction operand is outside the range allowed for that
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particular instruction field, <span class="command">as</span> 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 <dfn>relaxation</dfn>. 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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<ul class="menu">
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<li><a accesskey="1" href="Xtensa-Branch-Relaxation.html#Xtensa-Branch-Relaxation">Xtensa Branch Relaxation</a>: Relaxation of Branches.
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<li><a accesskey="2" href="Xtensa-Call-Relaxation.html#Xtensa-Call-Relaxation">Xtensa Call Relaxation</a>: Relaxation of Function Calls.
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<li><a accesskey="3" href="Xtensa-Immediate-Relaxation.html#Xtensa-Immediate-Relaxation">Xtensa Immediate Relaxation</a>: Relaxation of other Immediate Fields.
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</ul>
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</body></html>
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