71 lines
3.2 KiB
HTML
71 lines
3.2 KiB
HTML
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<html lang="en">
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<head>
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<title>Register Variables - STABS</title>
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<meta name="description" content="STABS">
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<meta name="generator" content="makeinfo 4.13">
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<link title="Top" rel="start" href="index.html#Top">
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<link rel="up" href="Variables.html#Variables" title="Variables">
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<link rel="prev" href="Global-Variables.html#Global-Variables" title="Global Variables">
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<link rel="next" href="Common-Blocks.html#Common-Blocks" title="Common Blocks">
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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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Copyright (C) 1992-2019 Free Software Foundation, Inc.
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Contributed by Cygnus Support. Written by Julia Menapace, Jim Kingdon,
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and David MacKenzie.
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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 no
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Invariant Sections, with no Front-Cover Texts, and with no Back-Cover
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Texts. A copy of the license is included in the section entitled ``GNU
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Free Documentation License''.-->
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</head>
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<body>
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<div class="node">
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<a name="Register-Variables"></a>
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<p>
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Next: <a rel="next" accesskey="n" href="Common-Blocks.html#Common-Blocks">Common Blocks</a>,
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Previous: <a rel="previous" accesskey="p" href="Global-Variables.html#Global-Variables">Global Variables</a>,
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Up: <a rel="up" accesskey="u" href="Variables.html#Variables">Variables</a>
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<hr>
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</div>
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<h3 class="section">4.3 Register Variables</h3>
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<p><a name="index-N_005fRSYM-29"></a><a name="index-C_005fRSYM-30"></a><!-- According to an old version of this manual, AIX uses C_RPSYM instead -->
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<!-- of C_RSYM. I am skeptical; this should be verified. -->
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Register variables have their own stab type, <code>N_RSYM</code>
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(<code>C_RSYM</code> for XCOFF), and their own symbol descriptor, ‘<samp><span class="samp">r</span></samp>’.
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The stab's value is the number of the register where the variable data
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will be stored.
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<!-- .stabs "name:type",N_RSYM,0,RegSize,RegNumber (Sun doc) -->
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<p>AIX defines a separate symbol descriptor ‘<samp><span class="samp">d</span></samp>’ for floating point
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registers. This seems unnecessary; why not just just give floating
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point registers different register numbers? I have not verified whether
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the compiler actually uses ‘<samp><span class="samp">d</span></samp>’.
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<p>If the register is explicitly allocated to a global variable, but not
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initialized, as in:
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<pre class="example"> register int g_bar asm ("%g5");
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</pre>
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<p class="noindent">then the stab may be emitted at the end of the object file, with
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the other bss symbols.
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</body></html>
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