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| <title>STABS: Transformations On Symbol Tables</title> |
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| <a name="Transformations-On-Symbol-Tables"></a> |
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| Previous: <a href="Symbol-Table-Format.html#Symbol-Table-Format" accesskey="p" rel="prev">Symbol Table Format</a>, Up: <a href="Symbol-Tables.html#Symbol-Tables" accesskey="u" rel="up">Symbol Tables</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Symbol-Types-Index.html#Symbol-Types-Index" title="Index" rel="index">Index</a>]</p> |
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| <a name="Transformations-on-Symbol-Tables"></a> |
| <h3 class="section">7.2 Transformations on Symbol Tables</h3> |
| |
| <p>The linker concatenates object files and does fixups of externally |
| defined symbols. |
| </p> |
| <p>You can see the transformations made on stab data by the assembler and |
| linker by examining the symbol table after each pass of the build. To |
| do this, use ‘<samp>nm -ap</samp>’, which dumps the symbol table, including |
| debugging information, unsorted. For stab entries the columns are: |
| <var>value</var>, <var>other</var>, <var>desc</var>, <var>type</var>, <var>string</var>. For |
| assembler and linker symbols, the columns are: <var>value</var>, <var>type</var>, |
| <var>string</var>. |
| </p> |
| <p>The low 5 bits of the stab type tell the linker how to relocate the |
| value of the stab. Thus for stab types like <code>N_RSYM</code> and |
| <code>N_LSYM</code>, where the value is an offset or a register number, the |
| low 5 bits are <code>N_ABS</code>, which tells the linker not to relocate the |
| value. |
| </p> |
| <p>Where the value of a stab contains an assembly language label, |
| it is transformed by each build step. The assembler turns it into a |
| relocatable address and the linker turns it into an absolute address. |
| </p> |
| <table class="menu" border="0" cellspacing="0"> |
| <tr><td align="left" valign="top">• <a href="Transformations-On-Static-Variables.html#Transformations-On-Static-Variables" accesskey="1">Transformations On Static Variables</a>:</td><td> </td><td align="left" valign="top"> |
| </td></tr> |
| <tr><td align="left" valign="top">• <a href="Transformations-On-Global-Variables.html#Transformations-On-Global-Variables" accesskey="2">Transformations On Global Variables</a>:</td><td> </td><td align="left" valign="top"> |
| </td></tr> |
| <tr><td align="left" valign="top">• <a href="Stab-Section-Transformations.html#Stab-Section-Transformations" accesskey="3">Stab Section Transformations</a>:</td><td> </td><td align="left" valign="top">For some object file formats, |
| things are a bit different. |
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