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| Next: <a href="Stabs-Format.html#Stabs-Format" accesskey="n" rel="next">Stabs Format</a>, Up: <a href="Overview.html#Overview" accesskey="u" rel="up">Overview</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="Overview-of-Debugging-Information-Flow"></a> |
| <h3 class="section">1.1 Overview of Debugging Information Flow</h3> |
| |
| <p>The GNU C compiler compiles C source in a <samp>.c</samp> file into assembly |
| language in a <samp>.s</samp> file, which the assembler translates into |
| a <samp>.o</samp> file, which the linker combines with other <samp>.o</samp> files and |
| libraries to produce an executable file. |
| </p> |
| <p>With the ‘<samp>-g</samp>’ option, GCC puts in the <samp>.s</samp> file additional |
| debugging information, which is slightly transformed by the assembler |
| and linker, and carried through into the final executable. This |
| debugging information describes features of the source file like line |
| numbers, the types and scopes of variables, and function names, |
| parameters, and scopes. |
| </p> |
| <p>For some object file formats, the debugging information is encapsulated |
| in assembler directives known collectively as <em>stab</em> (symbol table) |
| directives, which are interspersed with the generated code. Stabs are |
| the native format for debugging information in the a.out and XCOFF |
| object file formats. The GNU tools can also emit stabs in the COFF and |
| ECOFF object file formats. |
| </p> |
| <p>The assembler adds the information from stabs to the symbol information |
| it places by default in the symbol table and the string table of the |
| <samp>.o</samp> file it is building. The linker consolidates the <samp>.o</samp> |
| files into one executable file, with one symbol table and one string |
| table. Debuggers use the symbol and string tables in the executable as |
| a source of debugging information about the program. |
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