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<a name="Debugging-the-Analyzer"></a>
<div class="header">
<p>
Previous: <a href="Analyzer-Internals.html#Analyzer-Internals" accesskey="p" rel="prev">Analyzer Internals</a>, Up: <a href="Static-Analyzer.html#Static-Analyzer" accesskey="u" rel="up">Static Analyzer</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Option-Index.html#Option-Index" title="Index" rel="index">Index</a>]</p>
</div>
<hr>
<a name="Debugging-the-Analyzer-1"></a>
<h3 class="section">27.2 Debugging the Analyzer</h3>
<a name="index-analyzer_002c-debugging"></a>
<a name="index-static-analyzer_002c-debugging"></a>

<a name="Special-Functions-for-Debugging-the-Analyzer"></a>
<h4 class="subsection">27.2.1 Special Functions for Debugging the Analyzer</h4>

<p>The analyzer recognizes various special functions by name, for use
in debugging the analyzer.  Declarations can be seen in the testsuite
in <samp>analyzer-decls.h</samp>.  None of these functions are actually
implemented.
</p>
<p>Add:
</p><div class="smallexample">
<pre class="smallexample">  __analyzer_break ();
</pre></div>
<p>to the source being analyzed to trigger a breakpoint in the analyzer when
that source is reached.  By putting a series of these in the source, it&rsquo;s
much easier to effectively step through the program state as it&rsquo;s analyzed.
</p>
<div class="smallexample">
<pre class="smallexample">__analyzer_dump ();
</pre></div>

<p>will dump the copious information about the analyzer&rsquo;s state each time it
reaches the call in its traversal of the source.
</p>
<div class="smallexample">
<pre class="smallexample">__analyzer_dump_path ();
</pre></div>

<p>will emit a placeholder &ldquo;note&rdquo; diagnostic with a path to that call site,
if the analyzer finds a feasible path to it.
</p>
<p>The builtin <code>__analyzer_dump_exploded_nodes</code> will emit a warning
after analysis containing information on all of the exploded nodes at that
program point:
</p>
<div class="smallexample">
<pre class="smallexample">  __analyzer_dump_exploded_nodes (0);
</pre></div>

<p>will output the number of &ldquo;processed&rdquo; nodes, and the IDs of
both &ldquo;processed&rdquo; and &ldquo;merger&rdquo; nodes, such as:
</p>
<div class="smallexample">
<pre class="smallexample">warning: 2 processed enodes: [EN: 56, EN: 58] merger(s): [EN: 54-55, EN: 57, EN: 59]
</pre></div>

<p>With a non-zero argument
</p>
<div class="smallexample">
<pre class="smallexample">  __analyzer_dump_exploded_nodes (1);
</pre></div>

<p>it will also dump all of the states within the &ldquo;processed&rdquo; nodes.
</p>
<div class="smallexample">
<pre class="smallexample">   __analyzer_dump_region_model ();
</pre></div>
<p>will dump the region_model&rsquo;s state to stderr.
</p>
<div class="smallexample">
<pre class="smallexample">__analyzer_eval (expr);
</pre></div>
<p>will emit a warning with text &quot;TRUE&quot;, FALSE&quot; or &quot;UNKNOWN&quot; based on the
truthfulness of the argument.  This is useful for writing DejaGnu tests.
</p>

<a name="Other-Debugging-Techniques"></a>
<h4 class="subsection">27.2.2 Other Debugging Techniques</h4>

<p>One approach when tracking down where a particular bogus state is
introduced into the <code>exploded_graph</code> is to add custom code to
<code>region_model::validate</code>.
</p>
<p>For example, this custom code (added to <code>region_model::validate</code>)
breaks with an assertion failure when a variable called <code>ptr</code>
acquires a value that&rsquo;s unknown, using
<code>region_model::get_value_by_name</code> to locate the variable
</p>
<div class="smallexample">
<pre class="smallexample">    /* Find a variable matching &quot;ptr&quot;.  */
    svalue_id sid = get_value_by_name (&quot;ptr&quot;);
    if (!sid.null_p ())
      {
	svalue *sval = get_svalue (sid);
	gcc_assert (sval-&gt;get_kind () != SK_UNKNOWN);
      }
</pre></div>

<p>making it easier to investigate further in a debugger when this occurs.
</p>
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