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Re: dwarf2_get_pc_bounds problem
Your patch fixes the problems I was seeing.
Martin
On Fri, 2003-02-14 at 07:12, Daniel Jacobowitz wrote:
> On Fri, Feb 14, 2003 at 02:59:40AM -0800, Martin M. Hunt wrote:
> > I'm investigating several errors in recent versions of gdb and they all
> > seem to be caused by bogus values for lowpc and highpc returned from
> > dwarf2_get_pc_bounds(). I'm not a DWARF expert so maybe the problem is
> > bad debug info, but the code in dwarf2_get_pc_bounds seems suspicious.
> >
> > What I'm seeing is that with a program linked at 0x80000000, all the
> > highpc and lowpc look fine, except those derived from DW_AT_ranges
> > information. Those are all very small, like 0x100. Looking at the code
> > in dwarf2_get_pc_bounds(), most of it seems to be trying to calculate a
> > variable "base" which is then never used. Perhaps a simple addition was
> > left out?
>
> Ah, er, um, er.... I tested this, how the heck did it work? Aha, my
> test case involved multiple sections, so GCC used a base of 0. That's
> how.
>
> Could you try this obvious fix? Still doesn't fix Jakub's test (we
> really do need discontiguous ranges for that to work) but r_type
> searches one local block instead of going straight to the function.
>
> Oddly, I remember this happening before. I may have lost the addition
> in a merge somewhere.
>
> --
> Daniel Jacobowitz
> MontaVista Software Debian GNU/Linux Developer
>
> 2003-02-14 Daniel Jacobowitz <drow@mvista.com>
>
> * dwarf2read.c (dwarf2_get_pc_bounds): Offset addresses by base.
>
> Index: dwarf2read.c
> ===================================================================
> RCS file: /cvs/src/src/gdb/dwarf2read.c,v
> retrieving revision 1.85
> diff -u -p -r1.85 dwarf2read.c
> --- dwarf2read.c 4 Feb 2003 20:17:02 -0000 1.85
> +++ dwarf2read.c 14 Feb 2003 15:10:24 -0000
> @@ -2195,6 +2195,9 @@ dwarf2_get_pc_bounds (struct die_info *d
> return 0;
> }
>
> + range_beginning += base;
> + range_end += base;
> +
> /* FIXME: This is recording everything as a low-high
> segment of consecutive addresses. We should have a
> data structure for discontiguous block ranges