147 lines
7.4 KiB
HTML
147 lines
7.4 KiB
HTML
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<html lang="en">
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<head>
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<title>Frame Info - Debugging with GDB</title>
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<meta http-equiv="Content-Type" content="text/html">
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<meta name="description" content="Debugging with GDB">
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<meta name="generator" content="makeinfo 4.13">
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<link title="Top" rel="start" href="index.html#Top">
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<link rel="up" href="Stack.html#Stack" title="Stack">
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<link rel="prev" href="Selection.html#Selection" title="Selection">
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<link rel="next" href="Frame-Apply.html#Frame-Apply" title="Frame Apply">
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<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage">
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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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</head>
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<body>
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<div class="node">
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<a name="Frame-Info"></a>
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<p>
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Next: <a rel="next" accesskey="n" href="Frame-Apply.html#Frame-Apply">Frame Apply</a>,
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Previous: <a rel="previous" accesskey="p" href="Selection.html#Selection">Selection</a>,
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Up: <a rel="up" accesskey="u" href="Stack.html#Stack">Stack</a>
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<hr>
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</div>
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<h3 class="section">8.4 Information About a Frame</h3>
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<p>There are several other commands to print information about the selected
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stack frame.
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<dl>
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<dt><code>frame</code><dt><code>f</code><dd>When used without any argument, this command does not change which
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frame is selected, but prints a brief description of the currently
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selected stack frame. It can be abbreviated <code>f</code>. With an
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argument, this command is used to select a stack frame.
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See <a href="Selection.html#Selection">Selecting a Frame</a>.
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<p><a name="index-info-frame-541"></a><a name="index-info-f-_0040r_007b_0028_0040code_007binfo-frame_007d_0029_007d-542"></a><br><dt><code>info frame</code><dt><code>info f</code><dd>This command prints a verbose description of the selected stack frame,
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including:
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<ul>
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<li>the address of the frame
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<li>the address of the next frame down (called by this frame)
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<li>the address of the next frame up (caller of this frame)
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<li>the language in which the source code corresponding to this frame is written
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<li>the address of the frame's arguments
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<li>the address of the frame's local variables
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<li>the program counter saved in it (the address of execution in the caller frame)
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<li>which registers were saved in the frame
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</ul>
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<p class="noindent">The verbose description is useful when
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something has gone wrong that has made the stack format fail to fit
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the usual conventions.
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<br><dt><code>info frame </code><span class="roman">[</span> <var>frame-selection-spec</var> <span class="roman">]</span><dt><code>info f </code><span class="roman">[</span> <var>frame-selection-spec</var> <span class="roman">]</span><dd>Print a verbose description of the frame selected by
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<var>frame-selection-spec</var>. The <var>frame-selection-spec</var> is the
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same as for the <samp><span class="command">frame</span></samp> command (see <a href="Selection.html#Selection">Selecting a Frame</a>). The selected frame remains unchanged by this command.
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<p><a name="index-info-args-543"></a><br><dt><code>info args [-q]</code><dd>Print the arguments of the selected frame, each on a separate line.
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<p>The optional flag ‘<samp><span class="samp">-q</span></samp>’, which stands for ‘<samp><span class="samp">quiet</span></samp>’, disables
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printing header information and messages explaining why no argument
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have been printed.
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<br><dt><code>info args [-q] [-t </code><var>type_regexp</var><code>] [</code><var>regexp</var><code>]</code><dd>Like <kbd>info args</kbd>, but only print the arguments selected
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with the provided regexp(s).
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<p>If <var>regexp</var> is provided, print only the arguments whose names
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match the regular expression <var>regexp</var>.
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<p>If <var>type_regexp</var> is provided, print only the arguments whose
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types, as printed by the <code>whatis</code> command, match
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the regular expression <var>type_regexp</var>.
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If <var>type_regexp</var> contains space(s), it should be enclosed in
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quote characters. If needed, use backslash to escape the meaning
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of special characters or quotes.
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<p>If both <var>regexp</var> and <var>type_regexp</var> are provided, an argument
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is printed only if its name matches <var>regexp</var> and its type matches
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<var>type_regexp</var>.
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<br><dt><code>info locals [-q]</code><dd><a name="index-info-locals-544"></a>Print the local variables of the selected frame, each on a separate
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line. These are all variables (declared either static or automatic)
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accessible at the point of execution of the selected frame.
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<p>The optional flag ‘<samp><span class="samp">-q</span></samp>’, which stands for ‘<samp><span class="samp">quiet</span></samp>’, disables
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printing header information and messages explaining why no local variables
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have been printed.
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<br><dt><code>info locals [-q] [-t </code><var>type_regexp</var><code>] [</code><var>regexp</var><code>]</code><dd>Like <kbd>info locals</kbd>, but only print the local variables selected
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with the provided regexp(s).
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<p>If <var>regexp</var> is provided, print only the local variables whose names
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match the regular expression <var>regexp</var>.
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<p>If <var>type_regexp</var> is provided, print only the local variables whose
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types, as printed by the <code>whatis</code> command, match
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the regular expression <var>type_regexp</var>.
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If <var>type_regexp</var> contains space(s), it should be enclosed in
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quote characters. If needed, use backslash to escape the meaning
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of special characters or quotes.
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<p>If both <var>regexp</var> and <var>type_regexp</var> are provided, a local variable
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is printed only if its name matches <var>regexp</var> and its type matches
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<var>type_regexp</var>.
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<p>The command <kbd>info locals -q -t </kbd><var>type_regexp</var> can usefully be
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combined with the commands <kbd>frame apply</kbd> and <kbd>thread apply</kbd>.
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For example, your program might use Resource Acquisition Is
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Initialization types (RAII) such as <code>lock_something_t</code>: each
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local variable of type <code>lock_something_t</code> automatically places a
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lock that is destroyed when the variable goes out of scope. You can
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then list all acquired locks in your program by doing
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<pre class="smallexample"> thread apply all -s frame apply all -s info locals -q -t lock_something_t
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</pre>
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<p class="noindent">or the equivalent shorter form
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<pre class="smallexample"> tfaas i lo -q -t lock_something_t
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</pre>
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</dl>
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</body></html>
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