<html lang="en"> <head> <title>Stab - Using as</title> <meta http-equiv="Content-Type" content="text/html"> <meta name="description" content="Using as"> <meta name="generator" content="makeinfo 4.13"> <link title="Top" rel="start" href="index.html#Top"> <link rel="up" href="Pseudo-Ops.html#Pseudo-Ops" title="Pseudo Ops"> <link rel="prev" href="Space.html#Space" title="Space"> <link rel="next" href="String.html#String" title="String"> <link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage"> <!-- This file documents the GNU Assembler "as". Copyright (C) 1991-2015 Free Software Foundation, Inc. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with no Invariant Sections, with no Front-Cover Texts, and with no Back-Cover Texts. A copy of the license is included in the section entitled ``GNU Free Documentation License''. --> <meta http-equiv="Content-Style-Type" content="text/css"> <style type="text/css"><!-- pre.display { font-family:inherit } pre.format { font-family:inherit } pre.smalldisplay { font-family:inherit; font-size:smaller } pre.smallformat { font-family:inherit; font-size:smaller } pre.smallexample { font-size:smaller } pre.smalllisp { font-size:smaller } span.sc { font-variant:small-caps } span.roman { font-family:serif; font-weight:normal; } span.sansserif { font-family:sans-serif; font-weight:normal; } --></style> </head> <body> <div class="node"> <a name="Stab"></a> <p> Next: <a rel="next" accesskey="n" href="String.html#String">String</a>, Previous: <a rel="previous" accesskey="p" href="Space.html#Space">Space</a>, Up: <a rel="up" accesskey="u" href="Pseudo-Ops.html#Pseudo-Ops">Pseudo Ops</a> <hr> </div> <h3 class="section">7.86 <code>.stabd, .stabn, .stabs</code></h3> <p><a name="index-symbolic-debuggers_002c-information-for-470"></a><a name="index-g_t_0040code_007bstab_0040var_007bx_007d_007d-directives-471"></a>There are three directives that begin ‘<samp><span class="samp">.stab</span></samp>’. All emit symbols (see <a href="Symbols.html#Symbols">Symbols</a>), for use by symbolic debuggers. The symbols are not entered in the <samp><span class="command">as</span></samp> hash table: they cannot be referenced elsewhere in the source file. Up to five fields are required: <dl> <dt><var>string</var><dd>This is the symbol's name. It may contain any character except ‘<samp><span class="samp">\000</span></samp>’, so is more general than ordinary symbol names. Some debuggers used to code arbitrarily complex structures into symbol names using this field. <br><dt><var>type</var><dd>An absolute expression. The symbol'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. <br><dt><var>other</var><dd>An absolute expression. The symbol's “other” attribute is set to the low 8 bits of this expression. <br><dt><var>desc</var><dd>An absolute expression. The symbol's descriptor is set to the low 16 bits of this expression. <br><dt><var>value</var><dd>An absolute expression which becomes the symbol's value. </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! <a name="index-g_t_0040code_007bstabd_007d-directive-472"></a> <dl><dt><code>.stabd </code><var>type</var><code> , </code><var>other</var><code> , </code><var>desc</var><dd> The “name” 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't waste space in object files with empty strings. <p>The symbol'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-g_t_0040code_007bstabn_007d-directive-473"></a><br><dt><code>.stabn </code><var>type</var><code> , </code><var>other</var><code> , </code><var>desc</var><code> , </code><var>value</var><dd>The name of the symbol is set to the empty string <code>""</code>. <p><a name="index-g_t_0040code_007bstabs_007d-directive-474"></a><br><dt><code>.stabs </code><var>string</var><code> , </code><var>type</var><code> , </code><var>other</var><code> , </code><var>desc</var><code> , </code><var>value</var><dd>All five fields are specified. </dl> <!-- end have-stabs --> </body></html>