GDB 5.2/5.3 breakpoint bug
Daniel Jacobowitz
drow@mvista.com
Mon Jan 13 22:00:00 GMT 2003
On Wed, Jan 08, 2003 at 10:40:02PM -0500, Daniel Jacobowitz wrote:
> 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?
Ching Lai reported that this patch solved the problem, and I'm checking
it in. This fixes PR gdb/849.
> 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;
>
--
Daniel Jacobowitz
MontaVista Software Debian GNU/Linux Developer
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