mingw/info/gdb/Tracepoint-Actions.html

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  12 Node:<a name="Tracepoint%20Actions">Tracepoint Actions</a>,
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  19 <h4 class="subsection">Tracepoint Action Lists</h4>
  20
  21      <dl>
  22 <dt><code>actions </code>[<code></code><var>num</var><code></code>]<code></code>
  23      <dd>This command will prompt for a list of actions to be taken when the
  24 tracepoint is hit.  If the tracepoint number <var>num</var> is not
  25 specified, this command sets the actions for the one that was most
  26 recently defined (so that you can define a tracepoint and then say
  27 <code>actions</code> without bothering about its number).  You specify the
  28 actions themselves on the following lines, one action at a time, and
  29 terminate the actions list with a line containing just <code>end</code>.  So
  30 far, the only defined actions are <code>collect</code> and
  31 <code>while-stepping</code>.
  32
  33      <p>To remove all actions from a tracepoint, type <code>actions </code><var>num</var><code></code>
  34 and follow it immediately with <code>end</code>.
  35
  36      <pre class="smallexample">          (gdb) <b>collect </b><var>data</var><b></b> // collect some data
  37
  38           (gdb) <b>while-stepping 5</b> // single-step 5 times, collect data
  39
  40           (gdb) <b>end</b>              // signals the end of actions.
  41           </pre>
  42
  43      <p>In the following example, the action list begins with <code>collect</code>
  44 commands indicating the things to be collected when the tracepoint is
  45 hit.  Then, in order to single-step and collect additional data
  46 following the tracepoint, a <code>while-stepping</code> command is used,
  47 followed by the list of things to be collected while stepping.  The
  48 <code>while-stepping</code> command is terminated by its own separate
  49 <code>end</code> command.  Lastly, the action list is terminated by an
  50 <code>end</code> command.
  51
  52      <pre class="smallexample">          (gdb) <b>trace foo</b>
  53           (gdb) <b>actions</b>
  54           Enter actions for tracepoint 1, one per line:
  55           &gt; collect bar,baz
  56           &gt; collect $regs
  57           &gt; while-stepping 12
  58             &gt; collect $fp, $sp
  59             &gt; end
  60           end
  61           </pre>
  62
  63      <br><dt><code>collect </code><var>expr1</var><code>, </code><var>expr2</var><code>, ...</code>
  64      <dd>Collect values of the given expressions when the tracepoint is hit.
  65 This command accepts a comma-separated list of any valid expressions.
  66 In addition to global, static, or local variables, the following
  67 special arguments are supported:
  68
  69           <dl>
  70 <dt><code>$regs</code>
  71           <dd>collect all registers
  72
  73           <br><dt><code>$args</code>
  74           <dd>collect all function arguments
  75
  76           <br><dt><code>$locals</code>
  77           <dd>collect all local variables.
  78 </dl>
  79
  80      <p>You can give several consecutive <code>collect</code> commands, each one
  81 with a single argument, or one <code>collect</code> command with several
  82 arguments separated by commas: the effect is the same.
  83
  84      <p>The command <code>info scope</code> (see <a href="Symbols.html#Symbols">info scope</a>) is
  85 particularly useful for figuring out what data to collect.
  86
  87      <br><dt><code>while-stepping </code><var>n</var><code></code>
  88      <dd>Perform <var>n</var> single-step traces after the tracepoint, collecting
  89 new data at each step.  The <code>while-stepping</code> command is
  90 followed by the list of what to collect while stepping (followed by
  91 its own <code>end</code> command):
  92
  93      <pre class="smallexample">          &gt; while-stepping 12
  94             &gt; collect $regs, myglobal
  95             &gt; end
  96           &gt;
  97           </pre>
  98
  99      <p>You may abbreviate <code>while-stepping</code> as <code>ws</code> or
 100 <code>stepping</code>.
 101 </dl>
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