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Re: dwarf2_get_pc_bounds problem
- From: Daniel Jacobowitz <drow at mvista dot com>
- To: "Martin M. Hunt" <hunt at redhat dot com>
- Cc: gdb at sources dot redhat dot com
- Date: Fri, 14 Feb 2003 10:12:27 -0500
- Subject: Re: dwarf2_get_pc_bounds problem
- References: <1045220381.25349.10.camel@Dragon>
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