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77 lines
3.3 KiB
HTML
77 lines
3.3 KiB
HTML
4 years ago
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<title>RTL Declarations - GNU Compiler Collection (GCC) Internals</title>
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<link title="Top" rel="start" href="index.html#Top">
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<link rel="up" href="RTL.html#RTL" title="RTL">
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<link rel="prev" href="Conversions.html#Conversions" title="Conversions">
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Copyright (C) 1988-2015 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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(a) The FSF's Front-Cover Text is:
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A GNU Manual
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<body>
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<div class="node">
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<a name="RTL-Declarations"></a>
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<p>
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Next: <a rel="next" accesskey="n" href="Side-Effects.html#Side-Effects">Side Effects</a>,
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Previous: <a rel="previous" accesskey="p" href="Conversions.html#Conversions">Conversions</a>,
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Up: <a rel="up" accesskey="u" href="RTL.html#RTL">RTL</a>
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<hr>
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</div>
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<h3 class="section">13.14 Declarations</h3>
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<p><a name="index-RTL-declarations-3027"></a><a name="index-declarations_002c-RTL-3028"></a>
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Declaration expression codes do not represent arithmetic operations
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but rather state assertions about their operands.
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<a name="index-strict_005flow_005fpart-3029"></a>
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<a name="index-g_t_0040code_007bsubreg_007d_002c-in-_0040code_007bstrict_005flow_005fpart_007d-3030"></a>
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<dl><dt><code>(strict_low_part (subreg:</code><var>m</var><code> (reg:</code><var>n</var> <var>r</var><code>) 0))</code><dd>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>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 less than a word.
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</dl>
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</body></html>
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