binutils-gdb/gdb/sentinel-frame.c
Simon Marchi a154d838a7 gdb: add names to unwinders, add debug messages when looking for unwinder
I wrote this while debugging a problem where the expected unwinder for a
frame wasn't used.  It adds messages to show which unwinders are
considered for a frame, why they are not selected (if an exception is
thrown), and finally which unwinder is selected in the end.

To be able to show a meaningful, human-readable name for the unwinders,
add a "name" field to struct frame_unwind, and update all instances to
include a name.

Here's an example of the output:

    [frame] frame_unwind_find_by_frame: this_frame=0
    [frame] frame_unwind_try_unwinder: trying unwinder "dummy"
    [frame] frame_unwind_try_unwinder: no
    [frame] frame_unwind_try_unwinder: trying unwinder "dwarf2 tailcall"
    [frame] frame_unwind_try_unwinder: no
    [frame] frame_unwind_try_unwinder: trying unwinder "inline"
    [frame] frame_unwind_try_unwinder: no
    [frame] frame_unwind_try_unwinder: trying unwinder "jit"
    [frame] frame_unwind_try_unwinder: no
    [frame] frame_unwind_try_unwinder: trying unwinder "python"
    [frame] frame_unwind_try_unwinder: no
    [frame] frame_unwind_try_unwinder: trying unwinder "amd64 epilogue"
    [frame] frame_unwind_try_unwinder: no
    [frame] frame_unwind_try_unwinder: trying unwinder "i386 epilogue"
    [frame] frame_unwind_try_unwinder: no
    [frame] frame_unwind_try_unwinder: trying unwinder "dwarf2"
    [frame] frame_unwind_try_unwinder: yes

gdb/ChangeLog:

	* frame-unwind.h (struct frame_unwind) <name>: New.  Update
	instances everywhere to include this field.
	* frame-unwind.c (frame_unwind_try_unwinder,
	frame_unwind_find_by_frame): Add debug messages.

Change-Id: I813f17777422425f0d08b22499817b23922e8ddb
2021-06-29 12:05:03 -04:00

92 lines
2.5 KiB
C

/* Code dealing with register stack frames, for GDB, the GNU debugger.
Copyright (C) 1986-2021 Free Software Foundation, Inc.
This file is part of GDB.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
#include "defs.h"
#include "regcache.h"
#include "sentinel-frame.h"
#include "inferior.h"
#include "frame-unwind.h"
struct frame_unwind_cache
{
struct regcache *regcache;
};
void *
sentinel_frame_cache (struct regcache *regcache)
{
struct frame_unwind_cache *cache =
FRAME_OBSTACK_ZALLOC (struct frame_unwind_cache);
cache->regcache = regcache;
return cache;
}
/* Here the register value is taken direct from the register cache. */
static struct value *
sentinel_frame_prev_register (struct frame_info *this_frame,
void **this_prologue_cache,
int regnum)
{
struct frame_unwind_cache *cache
= (struct frame_unwind_cache *) *this_prologue_cache;
struct value *value;
value = cache->regcache->cooked_read_value (regnum);
VALUE_NEXT_FRAME_ID (value) = sentinel_frame_id;
return value;
}
static void
sentinel_frame_this_id (struct frame_info *this_frame,
void **this_prologue_cache,
struct frame_id *this_id)
{
/* The sentinel frame is used as a starting point for creating the
previous (inner most) frame. That frame's THIS_ID method will be
called to determine the inner most frame's ID. Not this one. */
internal_error (__FILE__, __LINE__, _("sentinel_frame_this_id called"));
}
static struct gdbarch *
sentinel_frame_prev_arch (struct frame_info *this_frame,
void **this_prologue_cache)
{
struct frame_unwind_cache *cache
= (struct frame_unwind_cache *) *this_prologue_cache;
return cache->regcache->arch ();
}
const struct frame_unwind sentinel_frame_unwind =
{
"sentinel",
SENTINEL_FRAME,
default_frame_unwind_stop_reason,
sentinel_frame_this_id,
sentinel_frame_prev_register,
NULL,
NULL,
NULL,
sentinel_frame_prev_arch,
};