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<title>Debugging with GDB: Symbols</title>
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<body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000">
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<a name="Symbols"></a>
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<div class="header">
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<p>
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Next: <a href="Altering.html#Altering" accesskey="n" rel="next">Altering</a>, Previous: <a href="Languages.html#Languages" accesskey="p" rel="previous">Languages</a>, Up: <a href="index.html#Top" accesskey="u" rel="up">Top</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="Examining-the-Symbol-Table"></a>
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<h2 class="chapter">16 Examining the Symbol Table</h2>
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<p>The commands described in this chapter allow you to inquire about the
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symbols (names of variables, functions and types) defined in your
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program. This information is inherent in the text of your program and
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does not change as your program executes. <small>GDB</small> finds it in your
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program’s symbol table, in the file indicated when you started <small>GDB</small>
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(see <a href="File-Options.html#File-Options">Choosing Files</a>), or by one of the
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file-management commands (see <a href="Files.html#Files">Commands to Specify Files</a>).
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</p>
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<a name="index-symbol-names"></a>
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<a name="index-names-of-symbols"></a>
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<a name="index-quoting-names"></a>
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<a name="quoting-names"></a><p>Occasionally, you may need to refer to symbols that contain unusual
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characters, which <small>GDB</small> ordinarily treats as word delimiters. The
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most frequent case is in referring to static variables in other
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source files (see <a href="Variables.html#Variables">Program Variables</a>). File names
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are recorded in object files as debugging symbols, but <small>GDB</small> would
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ordinarily parse a typical file name, like <samp>foo.c</samp>, as the three words
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‘<samp>foo</samp>’ ‘<samp>.</samp>’ ‘<samp>c</samp>’. To allow <small>GDB</small> to recognize
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‘<samp>foo.c</samp>’ as a single symbol, enclose it in single quotes; for example,
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</p>
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<div class="smallexample">
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<pre class="smallexample">p 'foo.c'::x
|
</pre></div>
|
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<p>looks up the value of <code>x</code> in the scope of the file <samp>foo.c</samp>.
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</p>
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<dl compact="compact">
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<dd><a name="index-case_002dinsensitive-symbol-names"></a>
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<a name="index-case-sensitivity-in-symbol-names"></a>
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<a name="index-set-case_002dsensitive"></a>
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</dd>
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<dt><code>set case-sensitive on</code></dt>
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<dt><code>set case-sensitive off</code></dt>
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<dt><code>set case-sensitive auto</code></dt>
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<dd><p>Normally, when <small>GDB</small> looks up symbols, it matches their names
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with case sensitivity determined by the current source language.
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Occasionally, you may wish to control that. The command <code>set
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case-sensitive</code> lets you do that by specifying <code>on</code> for
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case-sensitive matches or <code>off</code> for case-insensitive ones. If
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you specify <code>auto</code>, case sensitivity is reset to the default
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suitable for the source language. The default is case-sensitive
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matches for all languages except for Fortran, for which the default is
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case-insensitive matches.
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</p>
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<a name="index-show-case_002dsensitive"></a>
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</dd>
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<dt><code>show case-sensitive</code></dt>
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<dd><p>This command shows the current setting of case sensitivity for symbols
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lookups.
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</p>
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<a name="index-set-print-type-methods"></a>
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</dd>
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<dt><code>set print type methods</code></dt>
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<dt><code>set print type methods on</code></dt>
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<dt><code>set print type methods off</code></dt>
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<dd><p>Normally, when <small>GDB</small> prints a class, it displays any methods
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declared in that class. You can control this behavior either by
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passing the appropriate flag to <code>ptype</code>, or using <code>set
|
print type methods</code>. Specifying <code>on</code> will cause <small>GDB</small> to
|
display the methods; this is the default. Specifying <code>off</code> will
|
cause <small>GDB</small> to omit the methods.
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</p>
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<a name="index-show-print-type-methods"></a>
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</dd>
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<dt><code>show print type methods</code></dt>
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<dd><p>This command shows the current setting of method display when printing
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classes.
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</p>
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<a name="index-set-print-type-nested_002dtype_002dlimit"></a>
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</dd>
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<dt><code>set print type nested-type-limit <var>limit</var></code></dt>
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<dt><code>set print type nested-type-limit unlimited</code></dt>
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<dd><p>Set the limit of displayed nested types that the type printer will
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show. A <var>limit</var> of <code>unlimited</code> or <code>-1</code> will show all
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nested definitions. By default, the type printer will not show any nested
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types defined in classes.
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</p>
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<a name="index-show-print-type-nested_002dtype_002dlimit"></a>
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</dd>
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<dt><code>show print type nested-type-limit</code></dt>
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<dd><p>This command shows the current display limit of nested types when
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printing classes.
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</p>
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<a name="index-set-print-type-typedefs"></a>
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</dd>
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<dt><code>set print type typedefs</code></dt>
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<dt><code>set print type typedefs on</code></dt>
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<dt><code>set print type typedefs off</code></dt>
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<dd>
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<p>Normally, when <small>GDB</small> prints a class, it displays any typedefs
|
defined in that class. You can control this behavior either by
|
passing the appropriate flag to <code>ptype</code>, or using <code>set
|
print type typedefs</code>. Specifying <code>on</code> will cause <small>GDB</small> to
|
display the typedef definitions; this is the default. Specifying
|
<code>off</code> will cause <small>GDB</small> to omit the typedef definitions.
|
Note that this controls whether the typedef definition itself is
|
printed, not whether typedef names are substituted when printing other
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types.
|
</p>
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<a name="index-show-print-type-typedefs"></a>
|
</dd>
|
<dt><code>show print type typedefs</code></dt>
|
<dd><p>This command shows the current setting of typedef display when
|
printing classes.
|
</p>
|
<a name="index-info-address"></a>
|
<a name="index-address-of-a-symbol"></a>
|
</dd>
|
<dt><code>info address <var>symbol</var></code></dt>
|
<dd><p>Describe where the data for <var>symbol</var> is stored. For a register
|
variable, this says which register it is kept in. For a non-register
|
local variable, this prints the stack-frame offset at which the variable
|
is always stored.
|
</p>
|
<p>Note the contrast with ‘<samp>print &<var>symbol</var></samp>’, which does not work
|
at all for a register variable, and for a stack local variable prints
|
the exact address of the current instantiation of the variable.
|
</p>
|
<a name="index-info-symbol"></a>
|
<a name="index-symbol-from-address"></a>
|
<a name="index-closest-symbol-and-offset-for-an-address"></a>
|
</dd>
|
<dt><code>info symbol <var>addr</var></code></dt>
|
<dd><p>Print the name of a symbol which is stored at the address <var>addr</var>.
|
If no symbol is stored exactly at <var>addr</var>, <small>GDB</small> prints the
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nearest symbol and an offset from it:
|
</p>
|
<div class="smallexample">
|
<pre class="smallexample">(gdb) info symbol 0x54320
|
_initialize_vx + 396 in section .text
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</pre></div>
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<p>This is the opposite of the <code>info address</code> command. You can use
|
it to find out the name of a variable or a function given its address.
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</p>
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<p>For dynamically linked executables, the name of executable or shared
|
library containing the symbol is also printed:
|
</p>
|
<div class="smallexample">
|
<pre class="smallexample">(gdb) info symbol 0x400225
|
_start + 5 in section .text of /tmp/a.out
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(gdb) info symbol 0x2aaaac2811cf
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__read_nocancel + 6 in section .text of /usr/lib64/libc.so.6
|
</pre></div>
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<a name="index-demangle-1"></a>
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<a name="index-demangle"></a>
|
</dd>
|
<dt><code>demangle <span class="roman">[</span>-l <var>language</var><span class="roman">]</span> <span class="roman">[</span><var>--</var><span class="roman">]</span> <var>name</var></code></dt>
|
<dd><p>Demangle <var>name</var>.
|
If <var>language</var> is provided it is the name of the language to demangle
|
<var>name</var> in. Otherwise <var>name</var> is demangled in the current language.
|
</p>
|
<p>The ‘<samp>--</samp>’ option specifies the end of options,
|
and is useful when <var>name</var> begins with a dash.
|
</p>
|
<p>The parameter <code>demangle-style</code> specifies how to interpret the kind
|
of mangling used. See <a href="Print-Settings.html#Print-Settings">Print Settings</a>.
|
</p>
|
<a name="index-whatis"></a>
|
</dd>
|
<dt><code>whatis[/<var>flags</var>] [<var>arg</var>]</code></dt>
|
<dd><p>Print the data type of <var>arg</var>, which can be either an expression
|
or a name of a data type. With no argument, print the data type of
|
<code>$</code>, the last value in the value history.
|
</p>
|
<p>If <var>arg</var> is an expression (see <a href="Expressions.html#Expressions">Expressions</a>), it
|
is not actually evaluated, and any side-effecting operations (such as
|
assignments or function calls) inside it do not take place.
|
</p>
|
<p>If <var>arg</var> is a variable or an expression, <code>whatis</code> prints its
|
literal type as it is used in the source code. If the type was
|
defined using a <code>typedef</code>, <code>whatis</code> will <em>not</em> print
|
the data type underlying the <code>typedef</code>. If the type of the
|
variable or the expression is a compound data type, such as
|
<code>struct</code> or <code>class</code>, <code>whatis</code> never prints their
|
fields or methods. It just prints the <code>struct</code>/<code>class</code>
|
name (a.k.a. its <em>tag</em>). If you want to see the members of
|
such a compound data type, use <code>ptype</code>.
|
</p>
|
<p>If <var>arg</var> is a type name that was defined using <code>typedef</code>,
|
<code>whatis</code> <em>unrolls</em> only one level of that <code>typedef</code>.
|
Unrolling means that <code>whatis</code> will show the underlying type used
|
in the <code>typedef</code> declaration of <var>arg</var>. However, if that
|
underlying type is also a <code>typedef</code>, <code>whatis</code> will not
|
unroll it.
|
</p>
|
<p>For C code, the type names may also have the form ‘<samp>class
|
<var>class-name</var></samp>’, ‘<samp>struct <var>struct-tag</var></samp>’, ‘<samp>union
|
<var>union-tag</var></samp>’ or ‘<samp>enum <var>enum-tag</var></samp>’.
|
</p>
|
<p><var>flags</var> can be used to modify how the type is displayed.
|
Available flags are:
|
</p>
|
<dl compact="compact">
|
<dt><code>r</code></dt>
|
<dd><p>Display in “raw” form. Normally, <small>GDB</small> substitutes template
|
parameters and typedefs defined in a class when printing the class’
|
members. The <code>/r</code> flag disables this.
|
</p>
|
</dd>
|
<dt><code>m</code></dt>
|
<dd><p>Do not print methods defined in the class.
|
</p>
|
</dd>
|
<dt><code>M</code></dt>
|
<dd><p>Print methods defined in the class. This is the default, but the flag
|
exists in case you change the default with <code>set print type methods</code>.
|
</p>
|
</dd>
|
<dt><code>t</code></dt>
|
<dd><p>Do not print typedefs defined in the class. Note that this controls
|
whether the typedef definition itself is printed, not whether typedef
|
names are substituted when printing other types.
|
</p>
|
</dd>
|
<dt><code>T</code></dt>
|
<dd><p>Print typedefs defined in the class. This is the default, but the flag
|
exists in case you change the default with <code>set print type typedefs</code>.
|
</p>
|
</dd>
|
<dt><code>o</code></dt>
|
<dd><p>Print the offsets and sizes of fields in a struct, similar to what the
|
<code>pahole</code> tool does. This option implies the <code>/tm</code> flags.
|
</p>
|
<p>For example, given the following declarations:
|
</p>
|
<div class="smallexample">
|
<pre class="smallexample">struct tuv
|
{
|
int a1;
|
char *a2;
|
int a3;
|
};
|
|
struct xyz
|
{
|
int f1;
|
char f2;
|
void *f3;
|
struct tuv f4;
|
};
|
|
union qwe
|
{
|
struct tuv fff1;
|
struct xyz fff2;
|
};
|
|
struct tyu
|
{
|
int a1 : 1;
|
int a2 : 3;
|
int a3 : 23;
|
char a4 : 2;
|
int64_t a5;
|
int a6 : 5;
|
int64_t a7 : 3;
|
};
|
</pre></div>
|
|
<p>Issuing a <kbd>ptype /o struct tuv</kbd> command would print:
|
</p>
|
<div class="smallexample">
|
<pre class="smallexample">(gdb) ptype /o struct tuv
|
/* offset | size */ type = struct tuv {
|
/* 0 | 4 */ int a1;
|
/* XXX 4-byte hole */
|
/* 8 | 8 */ char *a2;
|
/* 16 | 4 */ int a3;
|
|
/* total size (bytes): 24 */
|
}
|
</pre></div>
|
|
<p>Notice the format of the first column of comments. There, you can
|
find two parts separated by the ‘<samp>|</samp>’ character: the <em>offset</em>,
|
which indicates where the field is located inside the struct, in
|
bytes, and the <em>size</em> of the field. Another interesting line is
|
the marker of a <em>hole</em> in the struct, indicating that it may be
|
possible to pack the struct and make it use less space by reorganizing
|
its fields.
|
</p>
|
<p>It is also possible to print offsets inside an union:
|
</p>
|
<div class="smallexample">
|
<pre class="smallexample">(gdb) ptype /o union qwe
|
/* offset | size */ type = union qwe {
|
/* 24 */ struct tuv {
|
/* 0 | 4 */ int a1;
|
/* XXX 4-byte hole */
|
/* 8 | 8 */ char *a2;
|
/* 16 | 4 */ int a3;
|
|
/* total size (bytes): 24 */
|
} fff1;
|
/* 40 */ struct xyz {
|
/* 0 | 4 */ int f1;
|
/* 4 | 1 */ char f2;
|
/* XXX 3-byte hole */
|
/* 8 | 8 */ void *f3;
|
/* 16 | 24 */ struct tuv {
|
/* 16 | 4 */ int a1;
|
/* XXX 4-byte hole */
|
/* 24 | 8 */ char *a2;
|
/* 32 | 4 */ int a3;
|
|
/* total size (bytes): 24 */
|
} f4;
|
|
/* total size (bytes): 40 */
|
} fff2;
|
|
/* total size (bytes): 40 */
|
}
|
</pre></div>
|
|
<p>In this case, since <code>struct tuv</code> and <code>struct xyz</code> occupy the
|
same space (because we are dealing with an union), the offset is not
|
printed for them. However, you can still examine the offset of each
|
of these structures’ fields.
|
</p>
|
<p>Another useful scenario is printing the offsets of a struct containing
|
bitfields:
|
</p>
|
<div class="smallexample">
|
<pre class="smallexample">(gdb) ptype /o struct tyu
|
/* offset | size */ type = struct tyu {
|
/* 0:31 | 4 */ int a1 : 1;
|
/* 0:28 | 4 */ int a2 : 3;
|
/* 0: 5 | 4 */ int a3 : 23;
|
/* 3: 3 | 1 */ signed char a4 : 2;
|
/* XXX 3-bit hole */
|
/* XXX 4-byte hole */
|
/* 8 | 8 */ int64_t a5;
|
/* 16: 0 | 4 */ int a6 : 5;
|
/* 16: 5 | 8 */ int64_t a7 : 3;
|
"/* XXX 7-byte padding */
|
|
/* total size (bytes): 24 */
|
}
|
</pre></div>
|
|
<p>Note how the offset information is now extended to also include the
|
first bit of the bitfield.
|
</p></dd>
|
</dl>
|
|
<a name="index-ptype"></a>
|
</dd>
|
<dt><code>ptype[/<var>flags</var>] [<var>arg</var>]</code></dt>
|
<dd><p><code>ptype</code> accepts the same arguments as <code>whatis</code>, but prints a
|
detailed description of the type, instead of just the name of the type.
|
See <a href="Expressions.html#Expressions">Expressions</a>.
|
</p>
|
<p>Contrary to <code>whatis</code>, <code>ptype</code> always unrolls any
|
<code>typedef</code>s in its argument declaration, whether the argument is
|
a variable, expression, or a data type. This means that <code>ptype</code>
|
of a variable or an expression will not print literally its type as
|
present in the source code—use <code>whatis</code> for that. <code>typedef</code>s at
|
the pointer or reference targets are also unrolled. Only <code>typedef</code>s of
|
fields, methods and inner <code>class typedef</code>s of <code>struct</code>s,
|
<code>class</code>es and <code>union</code>s are not unrolled even with <code>ptype</code>.
|
</p>
|
<p>For example, for this variable declaration:
|
</p>
|
<div class="smallexample">
|
<pre class="smallexample">typedef double real_t;
|
struct complex { real_t real; double imag; };
|
typedef struct complex complex_t;
|
complex_t var;
|
real_t *real_pointer_var;
|
</pre></div>
|
|
<p>the two commands give this output:
|
</p>
|
<div class="smallexample">
|
<pre class="smallexample">(gdb) whatis var
|
type = complex_t
|
(gdb) ptype var
|
type = struct complex {
|
real_t real;
|
double imag;
|
}
|
(gdb) whatis complex_t
|
type = struct complex
|
(gdb) whatis struct complex
|
type = struct complex
|
(gdb) ptype struct complex
|
type = struct complex {
|
real_t real;
|
double imag;
|
}
|
(gdb) whatis real_pointer_var
|
type = real_t *
|
(gdb) ptype real_pointer_var
|
type = double *
|
</pre></div>
|
|
<p>As with <code>whatis</code>, using <code>ptype</code> without an argument refers to
|
the type of <code>$</code>, the last value in the value history.
|
</p>
|
<a name="index-incomplete-type"></a>
|
<p>Sometimes, programs use opaque data types or incomplete specifications
|
of complex data structure. If the debug information included in the
|
program does not allow <small>GDB</small> to display a full declaration of
|
the data type, it will say ‘<samp><incomplete type></samp>’. For example,
|
given these declarations:
|
</p>
|
<div class="smallexample">
|
<pre class="smallexample"> struct foo;
|
struct foo *fooptr;
|
</pre></div>
|
|
<p>but no definition for <code>struct foo</code> itself, <small>GDB</small> will say:
|
</p>
|
<div class="smallexample">
|
<pre class="smallexample"> (gdb) ptype foo
|
$1 = <incomplete type>
|
</pre></div>
|
|
<p>“Incomplete type” is C terminology for data types that are not
|
completely specified.
|
</p>
|
<a name="index-unknown-type"></a>
|
<p>Othertimes, information about a variable’s type is completely absent
|
from the debug information included in the program. This most often
|
happens when the program or library where the variable is defined
|
includes no debug information at all. <small>GDB</small> knows the variable
|
exists from inspecting the linker/loader symbol table (e.g., the ELF
|
dynamic symbol table), but such symbols do not contain type
|
information. Inspecting the type of a (global) variable for which
|
<small>GDB</small> has no type information shows:
|
</p>
|
<div class="smallexample">
|
<pre class="smallexample"> (gdb) ptype var
|
type = <data variable, no debug info>
|
</pre></div>
|
|
<p>See <a href="Variables.html#Variables">no debug info variables</a>, for how to print the values
|
of such variables.
|
</p>
|
<a name="index-info-types"></a>
|
</dd>
|
<dt><code>info types [-q] [<var>regexp</var>]</code></dt>
|
<dd><p>Print a brief description of all types whose names match the regular
|
expression <var>regexp</var> (or all types in your program, if you supply
|
no argument). Each complete typename is matched as though it were a
|
complete line; thus, ‘<samp>i type value</samp>’ gives information on all
|
types in your program whose names include the string <code>value</code>, but
|
‘<samp>i type ^value$</samp>’ gives information only on types whose complete
|
name is <code>value</code>.
|
</p>
|
<p>In programs using different languages, <small>GDB</small> chooses the syntax
|
to print the type description according to the
|
‘<samp>set language</samp>’ value: using ‘<samp>set language auto</samp>’
|
(see <a href="Automatically.html#Automatically">Set Language Automatically</a>) means to use the
|
language of the type, other values mean to use
|
the manually specified language (see <a href="Manually.html#Manually">Set Language Manually</a>).
|
</p>
|
<p>This command differs from <code>ptype</code> in two ways: first, like
|
<code>whatis</code>, it does not print a detailed description; second, it
|
lists all source files and line numbers where a type is defined.
|
</p>
|
<p>The output from ‘<samp>into types</samp>’ is proceeded with a header line
|
describing what types are being listed. The optional flag ‘<samp>-q</samp>’,
|
which stands for ‘<samp>quiet</samp>’, disables printing this header
|
information.
|
</p>
|
<a name="index-info-type_002dprinters"></a>
|
</dd>
|
<dt><code>info type-printers</code></dt>
|
<dd><p>Versions of <small>GDB</small> that ship with Python scripting enabled may
|
have “type printers” available. When using <code>ptype</code> or
|
<code>whatis</code>, these printers are consulted when the name of a type
|
is needed. See <a href="Type-Printing-API.html#Type-Printing-API">Type Printing API</a>, for more information on writing
|
type printers.
|
</p>
|
<p><code>info type-printers</code> displays all the available type printers.
|
</p>
|
<a name="index-enable-type_002dprinter"></a>
|
<a name="index-disable-type_002dprinter"></a>
|
</dd>
|
<dt><code>enable type-printer <var>name</var>…</code></dt>
|
<dt><code>disable type-printer <var>name</var>…</code></dt>
|
<dd><p>These commands can be used to enable or disable type printers.
|
</p>
|
<a name="index-info-scope"></a>
|
<a name="index-local-variables"></a>
|
</dd>
|
<dt><code>info scope <var>location</var></code></dt>
|
<dd><p>List all the variables local to a particular scope. This command
|
accepts a <var>location</var> argument—a function name, a source line, or
|
an address preceded by a ‘<samp>*</samp>’, and prints all the variables local
|
to the scope defined by that location. (See <a href="Specify-Location.html#Specify-Location">Specify Location</a>, for
|
details about supported forms of <var>location</var>.) For example:
|
</p>
|
<div class="smallexample">
|
<pre class="smallexample">(gdb) <b>info scope command_line_handler</b>
|
Scope for command_line_handler:
|
Symbol rl is an argument at stack/frame offset 8, length 4.
|
Symbol linebuffer is in static storage at address 0x150a18, length 4.
|
Symbol linelength is in static storage at address 0x150a1c, length 4.
|
Symbol p is a local variable in register $esi, length 4.
|
Symbol p1 is a local variable in register $ebx, length 4.
|
Symbol nline is a local variable in register $edx, length 4.
|
Symbol repeat is a local variable at frame offset -8, length 4.
|
</pre></div>
|
|
<p>This command is especially useful for determining what data to collect
|
during a <em>trace experiment</em>, see <a href="Tracepoint-Actions.html#Tracepoint-Actions">collect</a>.
|
</p>
|
<a name="index-info-source"></a>
|
</dd>
|
<dt><code>info source</code></dt>
|
<dd><p>Show information about the current source file—that is, the source file for
|
the function containing the current point of execution:
|
</p><ul>
|
<li> the name of the source file, and the directory containing it,
|
</li><li> the directory it was compiled in,
|
</li><li> its length, in lines,
|
</li><li> which programming language it is written in,
|
</li><li> if the debug information provides it, the program that compiled the file
|
(which may include, e.g., the compiler version and command line arguments),
|
</li><li> whether the executable includes debugging information for that file, and
|
if so, what format the information is in (e.g., STABS, Dwarf 2, etc.), and
|
</li><li> whether the debugging information includes information about
|
preprocessor macros.
|
</li></ul>
|
|
|
<a name="index-info-sources"></a>
|
</dd>
|
<dt><code>info sources</code></dt>
|
<dd><p>Print the names of all source files in your program for which there is
|
debugging information, organized into two lists: files whose symbols
|
have already been read, and files whose symbols will be read when needed.
|
</p>
|
</dd>
|
<dt><code>info sources [-dirname | -basename] [--] [<var>regexp</var>]</code></dt>
|
<dd><p>Like ‘<samp>info sources</samp>’, but only print the names of the files
|
matching the provided <var>regexp</var>.
|
By default, the <var>regexp</var> is used to match anywhere in the filename.
|
If <code>-dirname</code>, only files having a dirname matching <var>regexp</var> are shown.
|
If <code>-basename</code>, only files having a basename matching <var>regexp</var>
|
are shown.
|
The matching is case-sensitive, except on operating systems that
|
have case-insensitive filesystem (e.g., MS-Windows).
|
</p>
|
<a name="index-info-functions"></a>
|
</dd>
|
<dt><code>info functions [-q] [-n]</code></dt>
|
<dd><p>Print the names and data types of all defined functions.
|
Similarly to ‘<samp>info types</samp>’, this command groups its output by source
|
files and annotates each function definition with its source line
|
number.
|
</p>
|
<p>In programs using different languages, <small>GDB</small> chooses the syntax
|
to print the function name and type according to the
|
‘<samp>set language</samp>’ value: using ‘<samp>set language auto</samp>’
|
(see <a href="Automatically.html#Automatically">Set Language Automatically</a>) means to use the
|
language of the function, other values mean to use
|
the manually specified language (see <a href="Manually.html#Manually">Set Language Manually</a>).
|
</p>
|
<p>The ‘<samp>-n</samp>’ flag excludes <em>non-debugging symbols</em> from the
|
results. A non-debugging symbol is a symbol that comes from the
|
executable’s symbol table, not from the debug information (for
|
example, DWARF) associated with the executable.
|
</p>
|
<p>The optional flag ‘<samp>-q</samp>’, which stands for ‘<samp>quiet</samp>’, disables
|
printing header information and messages explaining why no functions
|
have been printed.
|
</p>
|
</dd>
|
<dt><code>info functions [-q] [-n] [-t <var>type_regexp</var>] [<var>regexp</var>]</code></dt>
|
<dd><p>Like ‘<samp>info functions</samp>’, but only print the names and data types
|
of the functions selected with the provided regexp(s).
|
</p>
|
<p>If <var>regexp</var> is provided, print only the functions whose names
|
match the regular expression <var>regexp</var>.
|
Thus, ‘<samp>info fun step</samp>’ finds all functions whose
|
names include <code>step</code>; ‘<samp>info fun ^step</samp>’ finds those whose names
|
start with <code>step</code>. If a function name contains characters that
|
conflict with the regular expression language (e.g.
|
‘<samp>operator*()</samp>’), they may be quoted with a backslash.
|
</p>
|
<p>If <var>type_regexp</var> is provided, print only the functions whose
|
types, as printed by the <code>whatis</code> command, match
|
the regular expression <var>type_regexp</var>.
|
If <var>type_regexp</var> contains space(s), it should be enclosed in
|
quote characters. If needed, use backslash to escape the meaning
|
of special characters or quotes.
|
Thus, ‘<samp>info fun -t '^int ('</samp>’ finds the functions that return
|
an integer; ‘<samp>info fun -t '(.*int.*'</samp>’ finds the functions that
|
have an argument type containing int; ‘<samp>info fun -t '^int (' ^step</samp>’
|
finds the functions whose names start with <code>step</code> and that return
|
int.
|
</p>
|
<p>If both <var>regexp</var> and <var>type_regexp</var> are provided, a function
|
is printed only if its name matches <var>regexp</var> and its type matches
|
<var>type_regexp</var>.
|
</p>
|
|
<a name="index-info-variables"></a>
|
</dd>
|
<dt><code>info variables [-q] [-n]</code></dt>
|
<dd><p>Print the names and data types of all variables that are defined
|
outside of functions (i.e. excluding local variables).
|
The printed variables are grouped by source files and annotated with
|
their respective source line numbers.
|
</p>
|
<p>In programs using different languages, <small>GDB</small> chooses the syntax
|
to print the variable name and type according to the
|
‘<samp>set language</samp>’ value: using ‘<samp>set language auto</samp>’
|
(see <a href="Automatically.html#Automatically">Set Language Automatically</a>) means to use the
|
language of the variable, other values mean to use
|
the manually specified language (see <a href="Manually.html#Manually">Set Language Manually</a>).
|
</p>
|
<p>The ‘<samp>-n</samp>’ flag excludes non-debugging symbols from the results.
|
</p>
|
<p>The optional flag ‘<samp>-q</samp>’, which stands for ‘<samp>quiet</samp>’, disables
|
printing header information and messages explaining why no variables
|
have been printed.
|
</p>
|
</dd>
|
<dt><code>info variables [-q] [-n] [-t <var>type_regexp</var>] [<var>regexp</var>]</code></dt>
|
<dd><p>Like <kbd>info variables</kbd>, but only print the variables selected
|
with the provided regexp(s).
|
</p>
|
<p>If <var>regexp</var> is provided, print only the variables whose names
|
match the regular expression <var>regexp</var>.
|
</p>
|
<p>If <var>type_regexp</var> is provided, print only the variables whose
|
types, as printed by the <code>whatis</code> command, match
|
the regular expression <var>type_regexp</var>.
|
If <var>type_regexp</var> contains space(s), it should be enclosed in
|
quote characters. If needed, use backslash to escape the meaning
|
of special characters or quotes.
|
</p>
|
<p>If both <var>regexp</var> and <var>type_regexp</var> are provided, an argument
|
is printed only if its name matches <var>regexp</var> and its type matches
|
<var>type_regexp</var>.
|
</p>
|
<a name="index-info-modules"></a>
|
<a name="index-modules"></a>
|
</dd>
|
<dt><code>info modules <span class="roman">[</span>-q<span class="roman">]</span> <span class="roman">[</span><var>regexp</var><span class="roman">]</span></code></dt>
|
<dd><p>List all Fortran modules in the program, or all modules matching the
|
optional regular expression <var>regexp</var>.
|
</p>
|
<p>The optional flag ‘<samp>-q</samp>’, which stands for ‘<samp>quiet</samp>’, disables
|
printing header information and messages explaining why no modules
|
have been printed.
|
</p>
|
<a name="index-info-module"></a>
|
<a name="index-Fortran-modules_002c-information-about"></a>
|
<a name="index-functions-and-variables-by-Fortran-module"></a>
|
<a name="index-module-functions-and-variables"></a>
|
</dd>
|
<dt><code>info module functions <span class="roman">[</span>-q<span class="roman">]</span> <span class="roman">[</span>-m <var>module-regexp</var><span class="roman">]</span> <span class="roman">[</span>-t <var>type-regexp</var><span class="roman">]</span> <span class="roman">[</span><var>regexp</var><span class="roman">]</span></code></dt>
|
<dt><code>info module variables <span class="roman">[</span>-q<span class="roman">]</span> <span class="roman">[</span>-m <var>module-regexp</var><span class="roman">]</span> <span class="roman">[</span>-t <var>type-regexp</var><span class="roman">]</span> <span class="roman">[</span><var>regexp</var><span class="roman">]</span></code></dt>
|
<dd><p>List all functions or variables within all Fortran modules. The set
|
of functions or variables listed can be limited by providing some or
|
all of the optional regular expressions. If <var>module-regexp</var> is
|
provided, then only Fortran modules matching <var>module-regexp</var> will
|
be searched. Only functions or variables whose type matches the
|
optional regular expression <var>type-regexp</var> will be listed. And
|
only functions or variables whose name matches the optional regular
|
expression <var>regexp</var> will be listed.
|
</p>
|
<p>The optional flag ‘<samp>-q</samp>’, which stands for ‘<samp>quiet</samp>’, disables
|
printing header information and messages explaining why no functions
|
or variables have been printed.
|
</p>
|
<a name="index-info-classes"></a>
|
<a name="index-Objective_002dC_002c-classes-and-selectors"></a>
|
</dd>
|
<dt><code>info classes</code></dt>
|
<dt><code>info classes <var>regexp</var></code></dt>
|
<dd><p>Display all Objective-C classes in your program, or
|
(with the <var>regexp</var> argument) all those matching a particular regular
|
expression.
|
</p>
|
<a name="index-info-selectors"></a>
|
</dd>
|
<dt><code>info selectors</code></dt>
|
<dt><code>info selectors <var>regexp</var></code></dt>
|
<dd><p>Display all Objective-C selectors in your program, or
|
(with the <var>regexp</var> argument) all those matching a particular regular
|
expression.
|
</p>
|
|
<a name="index-opaque-data-types"></a>
|
<a name="index-set-opaque_002dtype_002dresolution"></a>
|
</dd>
|
<dt><code>set opaque-type-resolution on</code></dt>
|
<dd><p>Tell <small>GDB</small> to resolve opaque types. An opaque type is a type
|
declared as a pointer to a <code>struct</code>, <code>class</code>, or
|
<code>union</code>—for example, <code>struct MyType *</code>—that is used in one
|
source file although the full declaration of <code>struct MyType</code> is in
|
another source file. The default is on.
|
</p>
|
<p>A change in the setting of this subcommand will not take effect until
|
the next time symbols for a file are loaded.
|
</p>
|
</dd>
|
<dt><code>set opaque-type-resolution off</code></dt>
|
<dd><p>Tell <small>GDB</small> not to resolve opaque types. In this case, the type
|
is printed as follows:
|
</p><div class="smallexample">
|
<pre class="smallexample">{<no data fields>}
|
</pre></div>
|
|
<a name="index-show-opaque_002dtype_002dresolution"></a>
|
</dd>
|
<dt><code>show opaque-type-resolution</code></dt>
|
<dd><p>Show whether opaque types are resolved or not.
|
</p>
|
<a name="index-set-print-symbol_002dloading"></a>
|
<a name="index-print-messages-when-symbols-are-loaded"></a>
|
</dd>
|
<dt><code>set print symbol-loading</code></dt>
|
<dt><code>set print symbol-loading full</code></dt>
|
<dt><code>set print symbol-loading brief</code></dt>
|
<dt><code>set print symbol-loading off</code></dt>
|
<dd><p>The <code>set print symbol-loading</code> command allows you to control the
|
printing of messages when <small>GDB</small> loads symbol information.
|
By default a message is printed for the executable and one for each
|
shared library, and normally this is what you want. However, when
|
debugging apps with large numbers of shared libraries these messages
|
can be annoying.
|
When set to <code>brief</code> a message is printed for each executable,
|
and when <small>GDB</small> loads a collection of shared libraries at once
|
it will only print one message regardless of the number of shared
|
libraries. When set to <code>off</code> no messages are printed.
|
</p>
|
<a name="index-show-print-symbol_002dloading"></a>
|
</dd>
|
<dt><code>show print symbol-loading</code></dt>
|
<dd><p>Show whether messages will be printed when a <small>GDB</small> command
|
entered from the keyboard causes symbol information to be loaded.
|
</p>
|
<a name="index-maint-print-symbols"></a>
|
<a name="index-symbol-dump"></a>
|
<a name="index-maint-print-psymbols"></a>
|
<a name="index-partial-symbol-dump"></a>
|
<a name="index-maint-print-msymbols"></a>
|
<a name="index-minimal-symbol-dump"></a>
|
</dd>
|
<dt><code>maint print symbols <span class="roman">[</span>-pc <var>address</var><span class="roman">]</span> <span class="roman">[</span><var>filename</var><span class="roman">]</span></code></dt>
|
<dt><code>maint print symbols <span class="roman">[</span>-objfile <var>objfile</var><span class="roman">]</span> <span class="roman">[</span>-source <var>source</var><span class="roman">]</span> <span class="roman">[</span>--<span class="roman">]</span> <span class="roman">[</span><var>filename</var><span class="roman">]</span></code></dt>
|
<dt><code>maint print psymbols <span class="roman">[</span>-objfile <var>objfile</var><span class="roman">]</span> <span class="roman">[</span>-pc <var>address</var><span class="roman">]</span> <span class="roman">[</span>--<span class="roman">]</span> <span class="roman">[</span><var>filename</var><span class="roman">]</span></code></dt>
|
<dt><code>maint print psymbols <span class="roman">[</span>-objfile <var>objfile</var><span class="roman">]</span> <span class="roman">[</span>-source <var>source</var><span class="roman">]</span> <span class="roman">[</span>--<span class="roman">]</span> <span class="roman">[</span><var>filename</var><span class="roman">]</span></code></dt>
|
<dt><code>maint print msymbols <span class="roman">[</span>-objfile <var>objfile</var><span class="roman">]</span> <span class="roman">[</span>--<span class="roman">]</span> <span class="roman">[</span><var>filename</var><span class="roman">]</span></code></dt>
|
<dd><p>Write a dump of debugging symbol data into the file <var>filename</var> or
|
the terminal if <var>filename</var> is unspecified.
|
If <code>-objfile <var>objfile</var></code> is specified, only dump symbols for
|
that objfile.
|
If <code>-pc <var>address</var></code> is specified, only dump symbols for the file
|
with code at that address. Note that <var>address</var> may be a symbol like
|
<code>main</code>.
|
If <code>-source <var>source</var></code> is specified, only dump symbols for that
|
source file.
|
</p>
|
<p>These commands are used to debug the <small>GDB</small> symbol-reading code.
|
These commands do not modify internal <small>GDB</small> state, therefore
|
‘<samp>maint print symbols</samp>’ will only print symbols for already expanded symbol
|
tables.
|
You can use the command <code>info sources</code> to find out which files these are.
|
If you use ‘<samp>maint print psymbols</samp>’ instead, the dump shows information
|
about symbols that <small>GDB</small> only knows partially—that is, symbols
|
defined in files that <small>GDB</small> has skimmed, but not yet read completely.
|
Finally, ‘<samp>maint print msymbols</samp>’ just dumps “minimal symbols”, e.g.,
|
“ELF symbols”.
|
</p>
|
<p>See <a href="Files.html#Files">Commands to Specify Files</a>, for a discussion of how
|
<small>GDB</small> reads symbols (in the description of <code>symbol-file</code>).
|
</p>
|
<a name="index-maint-info-symtabs"></a>
|
<a name="index-maint-info-psymtabs"></a>
|
<a name="index-listing-GDB_0027s-internal-symbol-tables"></a>
|
<a name="index-symbol-tables_002c-listing-GDB_0027s-internal"></a>
|
<a name="index-full-symbol-tables_002c-listing-GDB_0027s-internal"></a>
|
<a name="index-partial-symbol-tables_002c-listing-GDB_0027s-internal"></a>
|
</dd>
|
<dt><code>maint info symtabs <span class="roman">[</span> <var>regexp</var> <span class="roman">]</span></code></dt>
|
<dt><code>maint info psymtabs <span class="roman">[</span> <var>regexp</var> <span class="roman">]</span></code></dt>
|
<dd>
|
<p>List the <code>struct symtab</code> or <code>struct partial_symtab</code>
|
structures whose names match <var>regexp</var>. If <var>regexp</var> is not
|
given, list them all. The output includes expressions which you can
|
copy into a <small>GDB</small> debugging this one to examine a particular
|
structure in more detail. For example:
|
</p>
|
<div class="smallexample">
|
<pre class="smallexample">(gdb) maint info psymtabs dwarf2read
|
{ objfile /home/gnu/build/gdb/gdb
|
((struct objfile *) 0x82e69d0)
|
{ psymtab /home/gnu/src/gdb/dwarf2read.c
|
((struct partial_symtab *) 0x8474b10)
|
readin no
|
fullname (null)
|
text addresses 0x814d3c8 -- 0x8158074
|
globals (* (struct partial_symbol **) 0x8507a08 @ 9)
|
statics (* (struct partial_symbol **) 0x40e95b78 @ 2882)
|
dependencies (none)
|
}
|
}
|
(gdb) maint info symtabs
|
(gdb)
|
</pre></div>
|
<p>We see that there is one partial symbol table whose filename contains
|
the string ‘<samp>dwarf2read</samp>’, belonging to the ‘<samp>gdb</samp>’ executable;
|
and we see that <small>GDB</small> has not read in any symtabs yet at all.
|
If we set a breakpoint on a function, that will cause <small>GDB</small> to
|
read the symtab for the compilation unit containing that function:
|
</p>
|
<div class="smallexample">
|
<pre class="smallexample">(gdb) break dwarf2_psymtab_to_symtab
|
Breakpoint 1 at 0x814e5da: file /home/gnu/src/gdb/dwarf2read.c,
|
line 1574.
|
(gdb) maint info symtabs
|
{ objfile /home/gnu/build/gdb/gdb
|
((struct objfile *) 0x82e69d0)
|
{ symtab /home/gnu/src/gdb/dwarf2read.c
|
((struct symtab *) 0x86c1f38)
|
dirname (null)
|
fullname (null)
|
blockvector ((struct blockvector *) 0x86c1bd0) (primary)
|
linetable ((struct linetable *) 0x8370fa0)
|
debugformat DWARF 2
|
}
|
}
|
(gdb)
|
</pre></div>
|
|
<a name="index-maint-info-line_002dtable"></a>
|
<a name="index-listing-GDB_0027s-internal-line-tables"></a>
|
<a name="index-line-tables_002c-listing-GDB_0027s-internal"></a>
|
</dd>
|
<dt><code>maint info line-table <span class="roman">[</span> <var>regexp</var> <span class="roman">]</span></code></dt>
|
<dd>
|
<p>List the <code>struct linetable</code> from all <code>struct symtab</code>
|
instances whose name matches <var>regexp</var>. If <var>regexp</var> is not
|
given, list the <code>struct linetable</code> from all <code>struct symtab</code>.
|
</p>
|
<a name="index-maint-set-symbol_002dcache_002dsize"></a>
|
<a name="index-symbol-cache-size"></a>
|
</dd>
|
<dt><code>maint set symbol-cache-size <var>size</var></code></dt>
|
<dd><p>Set the size of the symbol cache to <var>size</var>.
|
The default size is intended to be good enough for debugging
|
most applications. This option exists to allow for experimenting
|
with different sizes.
|
</p>
|
<a name="index-maint-show-symbol_002dcache_002dsize"></a>
|
</dd>
|
<dt><code>maint show symbol-cache-size</code></dt>
|
<dd><p>Show the size of the symbol cache.
|
</p>
|
<a name="index-maint-print-symbol_002dcache"></a>
|
<a name="index-symbol-cache_002c-printing-its-contents"></a>
|
</dd>
|
<dt><code>maint print symbol-cache</code></dt>
|
<dd><p>Print the contents of the symbol cache.
|
This is useful when debugging symbol cache issues.
|
</p>
|
<a name="index-maint-print-symbol_002dcache_002dstatistics"></a>
|
<a name="index-symbol-cache_002c-printing-usage-statistics"></a>
|
</dd>
|
<dt><code>maint print symbol-cache-statistics</code></dt>
|
<dd><p>Print symbol cache usage statistics.
|
This helps determine how well the cache is being utilized.
|
</p>
|
<a name="index-maint-flush_002dsymbol_002dcache"></a>
|
<a name="index-symbol-cache_002c-flushing"></a>
|
</dd>
|
<dt><code>maint flush-symbol-cache</code></dt>
|
<dd><p>Flush the contents of the symbol cache, all entries are removed.
|
This command is useful when debugging the symbol cache.
|
It is also useful when collecting performance data.
|
</p>
|
</dd>
|
</dl>
|
|
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|
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