1<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> 2<html> 3<!-- Copyright (C) 1992-2021 Free Software Foundation, Inc. 4Contributed by Cygnus Support. Written by Julia Menapace, Jim Kingdon, 5and David MacKenzie. 6 7Permission is granted to copy, distribute and/or modify this document 8under the terms of the GNU Free Documentation License, Version 1.3 or 9any later version published by the Free Software Foundation; with no 10Invariant Sections, with no Front-Cover Texts, and with no Back-Cover 11Texts. A copy of the license is included in the section entitled "GNU 12Free Documentation License". --> 13<!-- Created by GNU Texinfo 5.1, http://www.gnu.org/software/texinfo/ --> 14<head> 15<title>STABS: Register Variables</title> 16 17<meta name="description" content="STABS: Register Variables"> 18<meta name="keywords" content="STABS: Register Variables"> 19<meta name="resource-type" content="document"> 20<meta name="distribution" content="global"> 21<meta name="Generator" content="makeinfo"> 22<meta http-equiv="Content-Type" content="text/html; charset=utf-8"> 23<link href="index.html#Top" rel="start" title="Top"> 24<link href="Symbol-Types-Index.html#Symbol-Types-Index" rel="index" title="Symbol Types Index"> 25<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents"> 26<link href="Variables.html#Variables" rel="up" title="Variables"> 27<link href="Common-Blocks.html#Common-Blocks" rel="next" title="Common Blocks"> 28<link href="Global-Variables.html#Global-Variables" rel="previous" title="Global Variables"> 29<style type="text/css"> 30<!-- 31a.summary-letter {text-decoration: none} 32blockquote.smallquotation {font-size: smaller} 33div.display {margin-left: 3.2em} 34div.example {margin-left: 3.2em} 35div.indentedblock {margin-left: 3.2em} 36div.lisp {margin-left: 3.2em} 37div.smalldisplay {margin-left: 3.2em} 38div.smallexample {margin-left: 3.2em} 39div.smallindentedblock {margin-left: 3.2em; font-size: smaller} 40div.smalllisp {margin-left: 3.2em} 41kbd {font-style:oblique} 42pre.display {font-family: inherit} 43pre.format {font-family: inherit} 44pre.menu-comment {font-family: serif} 45pre.menu-preformatted {font-family: serif} 46pre.smalldisplay {font-family: inherit; font-size: smaller} 47pre.smallexample {font-size: smaller} 48pre.smallformat {font-family: inherit; font-size: smaller} 49pre.smalllisp {font-size: smaller} 50span.nocodebreak {white-space:nowrap} 51span.nolinebreak {white-space:nowrap} 52span.roman {font-family:serif; font-weight:normal} 53span.sansserif {font-family:sans-serif; font-weight:normal} 54ul.no-bullet {list-style: none} 55--> 56</style> 57 58 59</head> 60 61<body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000"> 62<a name="Register-Variables"></a> 63<div class="header"> 64<p> 65Next: <a href="Common-Blocks.html#Common-Blocks" accesskey="n" rel="next">Common Blocks</a>, Previous: <a href="Global-Variables.html#Global-Variables" accesskey="p" rel="previous">Global Variables</a>, Up: <a href="Variables.html#Variables" accesskey="u" rel="up">Variables</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Symbol-Types-Index.html#Symbol-Types-Index" title="Index" rel="index">Index</a>]</p> 66</div> 67<hr> 68<a name="Register-Variables-1"></a> 69<h3 class="section">4.3 Register Variables</h3> 70 71<a name="index-N_005fRSYM"></a> 72<a name="index-C_005fRSYM"></a> 73<p>Register variables have their own stab type, <code>N_RSYM</code> 74(<code>C_RSYM</code> for XCOFF), and their own symbol descriptor, ‘<samp>r</samp>’. 75The stab’s value is the number of the register where the variable data 76will be stored. 77</p> 78<p>AIX defines a separate symbol descriptor ‘<samp>d</samp>’ for floating point 79registers. This seems unnecessary; why not just just give floating 80point registers different register numbers? I have not verified whether 81the compiler actually uses ‘<samp>d</samp>’. 82</p> 83<p>If the register is explicitly allocated to a global variable, but not 84initialized, as in: 85</p> 86<div class="example"> 87<pre class="example">register int g_bar asm ("%g5"); 88</pre></div> 89 90<p>then the stab may be emitted at the end of the object file, with 91the other bss symbols. 92</p> 93 94 95 96</body> 97</html> 98