| <html lang="en"> |
| <head> |
| <title>Line Numbers - STABS</title> |
| <meta http-equiv="Content-Type" content="text/html"> |
| <meta name="description" content="STABS"> |
| <meta name="generator" content="makeinfo 4.13"> |
| <link title="Top" rel="start" href="index.html#Top"> |
| <link rel="up" href="Program-Structure.html#Program-Structure" title="Program Structure"> |
| <link rel="prev" href="Include-Files.html#Include-Files" title="Include Files"> |
| <link rel="next" href="Procedures.html#Procedures" title="Procedures"> |
| <link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage"> |
| <!-- |
| Copyright (C) 1992-2019 Free Software Foundation, Inc. |
| Contributed by Cygnus Support. Written by Julia Menapace, Jim Kingdon, |
| and David MacKenzie. |
| |
| 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="Line-Numbers"></a> |
| <p> |
| Next: <a rel="next" accesskey="n" href="Procedures.html#Procedures">Procedures</a>, |
| Previous: <a rel="previous" accesskey="p" href="Include-Files.html#Include-Files">Include Files</a>, |
| Up: <a rel="up" accesskey="u" href="Program-Structure.html#Program-Structure">Program Structure</a> |
| <hr> |
| </div> |
| |
| <h3 class="section">2.4 Line Numbers</h3> |
| |
| <p><a name="index-N_005fSLINE-10"></a>An <code>N_SLINE</code> symbol represents the start of a source line. The |
| desc field contains the line number and the value contains the code |
| address for the start of that source line. On most machines the address |
| is absolute; for stabs in sections (see <a href="Stab-Sections.html#Stab-Sections">Stab Sections</a>), it is |
| relative to the function in which the <code>N_SLINE</code> symbol occurs. |
| |
| <p><a name="index-N_005fDSLINE-11"></a><a name="index-N_005fBSLINE-12"></a>GNU documents <code>N_DSLINE</code> and <code>N_BSLINE</code> symbols for line |
| numbers in the data or bss segments, respectively. They are identical |
| to <code>N_SLINE</code> but are relocated differently by the linker. They |
| were intended to be used to describe the source location of a variable |
| declaration, but I believe that GCC2 actually puts the line number in |
| the desc field of the stab for the variable itself. GDB has been |
| ignoring these symbols (unless they contain a string field) since |
| at least GDB 3.5. |
| |
| <p>For single source lines that generate discontiguous code, such as flow |
| of control statements, there may be more than one line number entry for |
| the same source line. In this case there is a line number entry at the |
| start of each code range, each with the same line number. |
| |
| <p>XCOFF does not use stabs for line numbers. Instead, it uses COFF line |
| numbers (which are outside the scope of this document). Standard COFF |
| line numbers cannot deal with include files, but in XCOFF this is fixed |
| with the <code>C_BINCL</code> method of marking include files (see <a href="Include-Files.html#Include-Files">Include Files</a>). |
| |
| </body></html> |
| |