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162 lines
7.4 KiB
HTML
162 lines
7.4 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) 1988-2019 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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any later version published by the Free Software Foundation; with the
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Invariant Sections being "Free Software" and "Free Software Needs
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Free Documentation", with the Front-Cover Texts being "A GNU Manual,"
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and with the Back-Cover Texts as in (a) below.
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(a) The FSF's Back-Cover Text is: "You are free to copy and modify
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this GNU Manual. Buying copies from GNU Press supports the FSF in
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developing GNU and promoting software freedom." -->
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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>Line Tables In Python (Debugging with GDB)</title>
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<meta name="description" content="Line Tables In Python (Debugging with GDB)">
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<meta name="keywords" content="Line Tables In Python (Debugging with GDB)">
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<meta name="resource-type" content="document">
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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="Concept-Index.html#Concept-Index" rel="index" title="Concept Index">
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<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
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<link href="Python-API.html#Python-API" rel="up" title="Python API">
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<link href="Breakpoints-In-Python.html#Breakpoints-In-Python" rel="next" title="Breakpoints In Python">
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<link href="Symbol-Tables-In-Python.html#Symbol-Tables-In-Python" rel="prev" title="Symbol Tables In Python">
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</style>
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</head>
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<body lang="en">
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<a name="Line-Tables-In-Python"></a>
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<div class="header">
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<p>
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Next: <a href="Breakpoints-In-Python.html#Breakpoints-In-Python" accesskey="n" rel="next">Breakpoints In Python</a>, Previous: <a href="Symbol-Tables-In-Python.html#Symbol-Tables-In-Python" accesskey="p" rel="prev">Symbol Tables In Python</a>, Up: <a href="Python-API.html#Python-API" accesskey="u" rel="up">Python API</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
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</div>
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<hr>
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<a name="Manipulating-line-tables-using-Python"></a>
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<h4 class="subsubsection">23.2.2.29 Manipulating line tables using Python</h4>
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<a name="index-line-tables-in-python"></a>
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<a name="index-gdb_002eLineTable"></a>
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<p>Python code can request and inspect line table information from a
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symbol table that is loaded in <small>GDB</small>. A line table is a
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mapping of source lines to their executable locations in memory. To
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acquire the line table information for a particular symbol table, use
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the <code>linetable</code> function (see <a href="Symbol-Tables-In-Python.html#Symbol-Tables-In-Python">Symbol Tables In Python</a>).
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</p>
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<p>A <code>gdb.LineTable</code> is iterable. The iterator returns
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<code>LineTableEntry</code> objects that correspond to the source line and
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address for each line table entry. <code>LineTableEntry</code> objects have
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the following attributes:
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</p>
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<dl>
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<dt><a name="index-LineTableEntry_002eline"></a>Variable: <strong>LineTableEntry.line</strong></dt>
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<dd><p>The source line number for this line table entry. This number
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corresponds to the actual line of source. This attribute is not
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writable.
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</p></dd></dl>
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<dl>
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<dt><a name="index-LineTableEntry_002epc"></a>Variable: <strong>LineTableEntry.pc</strong></dt>
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<dd><p>The address that is associated with the line table entry where the
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executable code for that source line resides in memory. This
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attribute is not writable.
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</p></dd></dl>
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<p>As there can be multiple addresses for a single source line, you may
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receive multiple <code>LineTableEntry</code> objects with matching
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<code>line</code> attributes, but with different <code>pc</code> attributes. The
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iterator is sorted in ascending <code>pc</code> order. Here is a small
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example illustrating iterating over a line table.
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</p>
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<div class="smallexample">
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<pre class="smallexample">symtab = gdb.selected_frame().find_sal().symtab
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linetable = symtab.linetable()
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for line in linetable:
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print "Line: "+str(line.line)+" Address: "+hex(line.pc)
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</pre></div>
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<p>This will have the following output:
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</p>
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<div class="smallexample">
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<pre class="smallexample">Line: 33 Address: 0x4005c8L
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Line: 37 Address: 0x4005caL
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Line: 39 Address: 0x4005d2L
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Line: 40 Address: 0x4005f8L
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Line: 42 Address: 0x4005ffL
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Line: 44 Address: 0x400608L
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Line: 42 Address: 0x40060cL
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Line: 45 Address: 0x400615L
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</pre></div>
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<p>In addition to being able to iterate over a <code>LineTable</code>, it also
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has the following direct access methods:
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</p>
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<dl>
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<dt><a name="index-LineTable_002eline"></a>Function: <strong>LineTable.line</strong> <em>(line)</em></dt>
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<dd><p>Return a Python <code>Tuple</code> of <code>LineTableEntry</code> objects for any
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entries in the line table for the given <var>line</var>, which specifies
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the source code line. If there are no entries for that source code
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<var>line</var>, the Python <code>None</code> is returned.
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</p></dd></dl>
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<dl>
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<dt><a name="index-LineTable_002ehas_005fline"></a>Function: <strong>LineTable.has_line</strong> <em>(line)</em></dt>
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<dd><p>Return a Python <code>Boolean</code> indicating whether there is an entry in
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the line table for this source line. Return <code>True</code> if an entry
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is found, or <code>False</code> if not.
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</p></dd></dl>
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<dl>
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<dt><a name="index-LineTable_002esource_005flines"></a>Function: <strong>LineTable.source_lines</strong> <em>()</em></dt>
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<dd><p>Return a Python <code>List</code> of the source line numbers in the symbol
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table. Only lines with executable code locations are returned. The
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contents of the <code>List</code> will just be the source line entries
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represented as Python <code>Long</code> values.
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</p></dd></dl>
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<hr>
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<div class="header">
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<p>
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Next: <a href="Breakpoints-In-Python.html#Breakpoints-In-Python" accesskey="n" rel="next">Breakpoints In Python</a>, Previous: <a href="Symbol-Tables-In-Python.html#Symbol-Tables-In-Python" accesskey="p" rel="prev">Symbol Tables In Python</a>, Up: <a href="Python-API.html#Python-API" accesskey="u" rel="up">Python API</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
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</div>
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</body>
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</html>
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