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Re: [RFC] Is skip_prologue_using_sal actually usable?
Date: Tue, 09 Nov 2004 09:50:27 -0500
From: Andrew Cagney <cagney@gnu.org>
Mark,
DWARF 2 provides us with the exact location[s] of a prologue end, can we
use that?
DW_LNS_set_prologue_end is a DWARF3 thingy, which GCC doesn't generate
yet. The DWARF3 definition seems to match exactly what I have in mind
though.
skip_prologue, just like the traditional unwinder, only has to be ``good
enough''.
The problem here is that we as devlopers don't seem to agree on what
we mean by "good enough". As a result, the implementations in GDB
vary wildly throughout GDB.
The concrete problem I'm facing here is that skip_prologue_using_sal
as used by mips-tdep.c doesn't work for me on OpenBSD/mips64. It can
be fixed by applying the patch in the message that started this
thread, but if an implementation only has to be "good enough", I think
skip_prologue_using_sal is actually doing to much. Something like the
following code would be better:
static CORE_ADDR
sparc32_skip_prologue (CORE_ADDR start_pc)
{
struct symtab_and_line sal;
CORE_ADDR func_start, func_end;
struct sparc_frame_cache cache;
/* This is the preferred method, find the end of the prologue by
using the debugging information. */
if (find_pc_partial_function (start_pc, NULL, &func_start, &func_end))
{
sal = find_pc_line (func_start, 0);
if (sal.end < func_end
&& start_pc <= sal.end)
return sal.end;
}
return sparc_analyze_prologue (start_pc, 0xffffffffUL, &cache);
}
Mark