Re: GDB 5.2/5.3 breakpoint bug

[Daniel Jacobowitz <drow@mvista.com>]

On Wed, Jan 08, 2003 at 02:45:23PM -0800, Ching Lai wrote:
> Hi Daniel,
> 
> > > Comment out the line 2753 in gdb 5.21 and 2777 in gdb  5.3 and build
> them
> > on
> > > solaris seems to work OK with two test cases.
> > >
> > > Now the  question is to figure out why this line is added in gdb 5.21
> and
> > > gdb 5.3?
> >
> > The line is supposed to be there; it's so we know what is and isn't
> > inside a function.  You need to explain better why it's causing a
> > problem in find_pc_sect_line.
> 
> The problem is the linetable in different symbol tables have the
> same pc address in my testcase. One has valid number and the other one
> with line number as 0 (which is added by the extra record_line()).
> 
> In gdb 5.2.1 release of find_pc_set_line in symtab.c file.
> 
>   1788        /* Is this file's best line closer than the best in the other
> files?
>   1789           If so, record this file, and its best line, as best so far.
> */
>   1790
>   1791        if (prev && (!best || prev->pc > best->pc))
>   1792          {
>   1793            best = prev;
>   1794            best_symtab = s;
>   1795
>   1796            /* Discard BEST_END if it's before the PC of the current
> BEST.  */
>   1797            if (best_end <= best->pc)
>   1798              best_end = 0;
>   1799          }
> 
> Since the line 1791 prev->pc with valid line number is not greater than
> best->pc
> which has 0 as line number, so it did not pick up the correct symbol file.
> 
> If the record_line is need in gdb 5.2.1 and gdb 5.3, then the line 1791
> might
> need an extra condition to void picking up the wrong symbol table which has
> line
> number as 0 as added by record_line().
> 
> 1791        if (prev && (!best || prev->pc > best->pc) && (prev->line != 0))
> 
> 
> Here are the debugging  section of my observation.

Thanks for the extra detail.  I see what's going on now; I believe this
patch should also avoid the problem.  Does it?

-- 
Daniel Jacobowitz
MontaVista Software                         Debian GNU/Linux Developer

2002-03-08  Daniel Jacobowitz  <drow@mvista.com>

	* symtab.c (find_pc_sect_line): Don't consider end-of-function
	lines.

Index: symtab.c
===================================================================
RCS file: /cvs/src/src/gdb/symtab.c,v
retrieving revision 1.84
diff -u -p -r1.84 symtab.c
--- symtab.c	2 Jan 2003 14:27:26 -0000	1.84
+++ symtab.c	9 Jan 2003 03:38:36 -0000
@@ -2012,9 +2012,11 @@ find_pc_sect_line (CORE_ADDR pc, struct 
          the first line, prev will not be set.  */
 
       /* Is this file's best line closer than the best in the other files?
-         If so, record this file, and its best line, as best so far.  */
+         If so, record this file, and its best line, as best so far.  Don't
+         save prev if it represents the end of a function (i.e. line number
+         0) instead of a real line.  */
 
-      if (prev && (!best || prev->pc > best->pc))
+      if (prev && prev->line && (!best || prev->pc > best->pc))
 	{
 	  best = prev;
 	  best_symtab = s;