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<a name="Stab"></a>
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<hr>
<a name="g_t_002estabd_002c-_002estabn_002c-_002estabs"></a>
<h3 class="section">7.91 <code>.stabd, .stabn, .stabs</code></h3>

<a name="index-symbolic-debuggers_002c-information-for"></a>
<a name="index-stabx-directives"></a>
<p>There are three directives that begin &lsquo;<samp>.stab</samp>&rsquo;.
All emit symbols (see <a href="Symbols.html#Symbols">Symbols</a>), for use by symbolic debuggers.
The symbols are not entered in the <code>as</code> hash table: they
cannot be referenced elsewhere in the source file.
Up to five fields are required:
</p>
<dl compact="compact">
<dt><var>string</var></dt>
<dd><p>This is the symbol&rsquo;s name.  It may contain any character except
&lsquo;<samp>\000</samp>&rsquo;, so is more general than ordinary symbol names.  Some
debuggers used to code arbitrarily complex structures into symbol names
using this field.
</p>
</dd>
<dt><var>type</var></dt>
<dd><p>An absolute expression.  The symbol&rsquo;s type is set to the low 8 bits of
this expression.  Any bit pattern is permitted, but <code>ld</code>
and debuggers choke on silly bit patterns.
</p>
</dd>
<dt><var>other</var></dt>
<dd><p>An absolute expression.  The symbol&rsquo;s &ldquo;other&rdquo; attribute is set to the
low 8 bits of this expression.
</p>
</dd>
<dt><var>desc</var></dt>
<dd><p>An absolute expression.  The symbol&rsquo;s descriptor is set to the low 16
bits of this expression.
</p>
</dd>
<dt><var>value</var></dt>
<dd><p>An absolute expression which becomes the symbol&rsquo;s value.
</p></dd>
</dl>

<p>If a warning is detected while reading a <code>.stabd</code>, <code>.stabn</code>,
or <code>.stabs</code> statement, the symbol has probably already been created;
you get a half-formed symbol in your object file.  This is
compatible with earlier assemblers!
</p>
<dl compact="compact">
<dd><a name="index-stabd-directive"></a>
</dd>
<dt><code>.stabd <var>type</var> , <var>other</var> , <var>desc</var></code></dt>
<dd>
<p>The &ldquo;name&rdquo; of the symbol generated is not even an empty string.
It is a null pointer, for compatibility.  Older assemblers used a
null pointer so they didn&rsquo;t waste space in object files with empty
strings.
</p>
<p>The symbol&rsquo;s value is set to the location counter,
relocatably.  When your program is linked, the value of this symbol
is the address of the location counter when the <code>.stabd</code> was
assembled.
</p>
<a name="index-stabn-directive"></a>
</dd>
<dt><code>.stabn <var>type</var> , <var>other</var> , <var>desc</var> , <var>value</var></code></dt>
<dd><p>The name of the symbol is set to the empty string <code>&quot;&quot;</code>.
</p>
<a name="index-stabs-directive"></a>
</dd>
<dt><code>.stabs <var>string</var> ,  <var>type</var> , <var>other</var> , <var>desc</var> , <var>value</var></code></dt>
<dd><p>All five fields are specified.
</p></dd>
</dl>

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