mingw/info/stabs/Line-Numbers.html

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  12 Node:<a name="Line%20Numbers">Line Numbers</a>,
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  19 <h3 class="section">Line Numbers</h3>
  20
  21    <p>An <code>N_SLINE</code> symbol represents the start of a source line.  The
  22 desc field contains the line number and the value contains the code
  23 address for the start of that source line.  On most machines the address
  24 is absolute; for stabs in sections (see <a href="Stab-Sections.html#Stab%20Sections">Stab Sections</a>), it is
  25 relative to the function in which the <code>N_SLINE</code> symbol occurs.
  26
  27    <p>GNU documents <code>N_DSLINE</code> and <code>N_BSLINE</code> symbols for line
  28 numbers in the data or bss segments, respectively.  They are identical
  29 to <code>N_SLINE</code> but are relocated differently by the linker.  They
  30 were intended to be used to describe the source location of a variable
  31 declaration, but I believe that GCC2 actually puts the line number in
  32 the desc field of the stab for the variable itself.  GDB has been
  33 ignoring these symbols (unless they contain a string field) since
  34 at least GDB 3.5.
  35
  36    <p>For single source lines that generate discontiguous code, such as flow
  37 of control statements, there may be more than one line number entry for
  38 the same source line.  In this case there is a line number entry at the
  39 start of each code range, each with the same line number.
  40
  41    <p>XCOFF does not use stabs for line numbers.  Instead, it uses COFF line
  42 numbers (which are outside the scope of this document).  Standard COFF
  43 line numbers cannot deal with include files, but in XCOFF this is fixed
  44 with the <code>C_BINCL</code> method of marking include files (see <a href="Include-Files.html#Include%20Files">Include Files</a>).
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