102 lines
4.6 KiB
HTML
102 lines
4.6 KiB
HTML
<!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) 1992-2017 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 5.2, http://www.gnu.org/software/texinfo/ -->
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<head>
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<title>STABS: Flow</title>
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<meta name="description" content="STABS: Flow">
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<meta name="keywords" content="STABS: Flow">
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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="Overview.html#Overview" rel="up" title="Overview">
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<link href="Stabs-Format.html#Stabs-Format" rel="next" title="Stabs Format">
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<link href="Overview.html#Overview" rel="prev" title="Overview">
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</head>
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<body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000">
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<a name="Flow"></a>
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<div class="header">
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<p>
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Next: <a href="Stabs-Format.html#Stabs-Format" accesskey="n" rel="next">Stabs Format</a>, Up: <a href="Overview.html#Overview" accesskey="u" rel="up">Overview</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="Overview-of-Debugging-Information-Flow"></a>
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<h3 class="section">1.1 Overview of Debugging Information Flow</h3>
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<p>The GNU C compiler compiles C source in a <samp>.c</samp> file into assembly
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language in a <samp>.s</samp> file, which the assembler translates into
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a <samp>.o</samp> file, which the linker combines with other <samp>.o</samp> files and
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libraries to produce an executable file.
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</p>
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<p>With the ‘<samp>-g</samp>’ option, GCC puts in the <samp>.s</samp> file additional
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debugging information, which is slightly transformed by the assembler
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and linker, and carried through into the final executable. This
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debugging information describes features of the source file like line
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numbers, the types and scopes of variables, and function names,
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parameters, and scopes.
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</p>
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<p>For some object file formats, the debugging information is encapsulated
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in assembler directives known collectively as <em>stab</em> (symbol table)
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directives, which are interspersed with the generated code. Stabs are
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the native format for debugging information in the a.out and XCOFF
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object file formats. The GNU tools can also emit stabs in the COFF and
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ECOFF object file formats.
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</p>
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<p>The assembler adds the information from stabs to the symbol information
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it places by default in the symbol table and the string table of the
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<samp>.o</samp> file it is building. The linker consolidates the <samp>.o</samp>
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files into one executable file, with one symbol table and one string
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table. Debuggers use the symbol and string tables in the executable as
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a source of debugging information about the program.
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</p>
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</body>
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</html>
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