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111 lines
4.8 KiB
HTML
111 lines
4.8 KiB
HTML
4 years ago
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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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<!-- 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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<!-- Created by GNU Texinfo 6.4, http://www.gnu.org/software/texinfo/ -->
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<head>
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<title>Transformations On Global Variables (STABS)</title>
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<meta name="description" content="Transformations On Global Variables (STABS)">
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<meta name="keywords" content="Transformations On Global Variables (STABS)">
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<meta name="resource-type" content="document">
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<meta name="distribution" content="global">
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<meta name="Generator" content="makeinfo">
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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<link href="index.html#Top" rel="start" title="Top">
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<link href="Symbol-Types-Index.html#Symbol-Types-Index" rel="index" title="Symbol Types Index">
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<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
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<link href="Transformations-On-Symbol-Tables.html#Transformations-On-Symbol-Tables" rel="up" title="Transformations On Symbol Tables">
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<link href="Stab-Section-Transformations.html#Stab-Section-Transformations" rel="next" title="Stab Section Transformations">
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<link href="Transformations-On-Static-Variables.html#Transformations-On-Static-Variables" rel="prev" title="Transformations On Static Variables">
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<style type="text/css">
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a.summary-letter {text-decoration: none}
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span.nolinebreak {white-space: nowrap}
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ul.no-bullet {list-style: none}
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-->
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</style>
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</head>
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<body lang="en">
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<a name="Transformations-On-Global-Variables"></a>
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<div class="header">
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<p>
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Next: <a href="Stab-Section-Transformations.html#Stab-Section-Transformations" accesskey="n" rel="next">Stab Section Transformations</a>, Previous: <a href="Transformations-On-Static-Variables.html#Transformations-On-Static-Variables" accesskey="p" rel="prev">Transformations On Static Variables</a>, Up: <a href="Transformations-On-Symbol-Tables.html#Transformations-On-Symbol-Tables" accesskey="u" rel="up">Transformations On Symbol Tables</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>
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</div>
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<hr>
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<a name="Transformations-on-Global-Variables"></a>
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<h4 class="subsection">7.2.2 Transformations on Global Variables</h4>
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<p>Stabs for global variables do not contain location information. In
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this case, the debugger finds location information in the assembler or
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linker symbol table entry describing the variable. The source line:
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</p>
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<div class="example">
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<pre class="example">char g_foo = 'c';
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</pre></div>
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<p>generates the stab:
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</p>
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<div class="example">
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<pre class="example">.stabs "g_foo:G2",32,0,0,0
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</pre></div>
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<p>The variable is represented by two symbol table entries in the object
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file (see below). The first one originated as a stab. The second one
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is an external symbol. The upper case ‘<samp>D</samp>’ signifies that the
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<code>n_type</code> field of the symbol table contains 7, <code>N_DATA</code> with
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local linkage. The stab’s value is zero since the value is not used for
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<code>N_GSYM</code> stabs. The value of the linker symbol is the relocatable
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address corresponding to the variable.
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</p>
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<div class="example">
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<pre class="example">00000000 - 00 0000 GSYM g_foo:G2
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00000080 D _g_foo
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</pre></div>
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<p>These entries as transformed by the linker. The linker symbol table
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entry now holds an absolute address:
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</p>
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<div class="example">
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<pre class="example">00000000 - 00 0000 GSYM g_foo:G2
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…
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0000e008 D _g_foo
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</pre></div>
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</body>
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</html>
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