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binutils-gdb/gdb/frame.c

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/* Cache and manage frames for GDB, the GNU debugger.
Copyright 1986, 1987, 1989, 1991, 1994, 1995, 1996, 1998, 2000,
2001, 2002, 2003, 2004 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 2 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, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA. */
#include "defs.h"
#include "frame.h"
#include "target.h"
#include "value.h"
#include "inferior.h" /* for inferior_ptid */
#include "regcache.h"
#include "gdb_assert.h"
#include "gdb_string.h"
#include "user-regs.h"
#include "gdb_obstack.h"
#include "dummy-frame.h"
#include "sentinel-frame.h"
#include "gdbcore.h"
#include "annotate.h"
#include "language.h"
#include "frame-unwind.h"
#include "frame-base.h"
#include "command.h"
#include "gdbcmd.h"
#include "observer.h"
static struct frame_info *get_prev_frame_1 (struct frame_info *this_frame);
/* We keep a cache of stack frames, each of which is a "struct
frame_info". The innermost one gets allocated (in
wait_for_inferior) each time the inferior stops; current_frame
points to it. Additional frames get allocated (in get_prev_frame)
as needed, and are chained through the next and prev fields. Any
time that the frame cache becomes invalid (most notably when we
execute something, but also if we change how we interpret the
frames (e.g. "set heuristic-fence-post" in mips-tdep.c, or anything
which reads new symbols)), we should call reinit_frame_cache. */
struct frame_info
{
/* Level of this frame. The inner-most (youngest) frame is at level
0. As you move towards the outer-most (oldest) frame, the level
increases. This is a cached value. It could just as easily be
computed by counting back from the selected frame to the inner
most frame. */
/* NOTE: cagney/2002-04-05: Perhaps a level of ``-1'' should be
reserved to indicate a bogus frame - one that has been created
just to keep GDB happy (GDB always needs a frame). For the
moment leave this as speculation. */
int level;
/* The frame's type. */
/* FIXME: cagney/2004-05-01: Should instead just use ->unwind->type.
Unfortunately, legacy_get_prev_frame is still explicitly setting
the type. Eliminate that method and this field can be
eliminated. */
enum frame_type type;
/* For each register, address of where it was saved on entry to the
frame, or zero if it was not saved on entry to this frame. This
includes special registers such as pc and fp saved in special
ways in the stack frame. The SP_REGNUM is even more special, the
address here is the sp for the previous frame, not the address
where the sp was saved. */
/* Allocated by frame_saved_regs_zalloc () which is called /
initialized by DEPRECATED_FRAME_INIT_SAVED_REGS(). */
CORE_ADDR *saved_regs; /*NUM_REGS + NUM_PSEUDO_REGS*/
/* Anything extra for this structure that may have been defined in
the machine dependent files. */
/* Allocated by frame_extra_info_zalloc () which is called /
initialized by DEPRECATED_INIT_EXTRA_FRAME_INFO */
struct frame_extra_info *extra_info;
/* The frame's low-level unwinder and corresponding cache. The
low-level unwinder is responsible for unwinding register values
for the previous frame. The low-level unwind methods are
selected based on the presence, or otherwise, of register unwind
information such as CFI. */
void *prologue_cache;
const struct frame_unwind *unwind;
/* Cached copy of the previous frame's resume address. */
struct {
int p;
CORE_ADDR value;
} prev_pc;
/* Cached copy of the previous frame's function address. */
struct
{
CORE_ADDR addr;
int p;
} prev_func;
/* This frame's ID. */
struct
{
int p;
struct frame_id value;
} this_id;
/* The frame's high-level base methods, and corresponding cache.
The high level base methods are selected based on the frame's
debug info. */
const struct frame_base *base;
void *base_cache;
/* Pointers to the next (down, inner, younger) and previous (up,
outer, older) frame_info's in the frame cache. */
struct frame_info *next; /* down, inner, younger */
int prev_p;
struct frame_info *prev; /* up, outer, older */
};
/* Flag to control debugging. */
static int frame_debug;
/* Flag to indicate whether backtraces should stop at main et.al. */
static int backtrace_past_main;
static unsigned int backtrace_limit = UINT_MAX;
void
fprint_frame_id (struct ui_file *file, struct frame_id id)
{
fprintf_unfiltered (file, "{stack=0x%s,code=0x%s,special=0x%s}",
paddr_nz (id.stack_addr),
paddr_nz (id.code_addr),
paddr_nz (id.special_addr));
}
static void
fprint_frame_type (struct ui_file *file, enum frame_type type)
{
switch (type)
{
case UNKNOWN_FRAME:
fprintf_unfiltered (file, "UNKNOWN_FRAME");
return;
case NORMAL_FRAME:
fprintf_unfiltered (file, "NORMAL_FRAME");
return;
case DUMMY_FRAME:
fprintf_unfiltered (file, "DUMMY_FRAME");
return;
case SIGTRAMP_FRAME:
fprintf_unfiltered (file, "SIGTRAMP_FRAME");
return;
default:
fprintf_unfiltered (file, "<unknown type>");
return;
};
}
static void
fprint_frame (struct ui_file *file, struct frame_info *fi)
{
if (fi == NULL)
{
fprintf_unfiltered (file, "<NULL frame>");
return;
}
fprintf_unfiltered (file, "{");
fprintf_unfiltered (file, "level=%d", fi->level);
fprintf_unfiltered (file, ",");
fprintf_unfiltered (file, "type=");
fprint_frame_type (file, fi->type);
fprintf_unfiltered (file, ",");
fprintf_unfiltered (file, "unwind=");
if (fi->unwind != NULL)
gdb_print_host_address (fi->unwind, file);
else
fprintf_unfiltered (file, "<unknown>");
fprintf_unfiltered (file, ",");
fprintf_unfiltered (file, "pc=");
if (fi->next != NULL && fi->next->prev_pc.p)
fprintf_unfiltered (file, "0x%s", paddr_nz (fi->next->prev_pc.value));
else
fprintf_unfiltered (file, "<unknown>");
fprintf_unfiltered (file, ",");
fprintf_unfiltered (file, "id=");
if (fi->this_id.p)
fprint_frame_id (file, fi->this_id.value);
else
fprintf_unfiltered (file, "<unknown>");
fprintf_unfiltered (file, ",");
fprintf_unfiltered (file, "func=");
if (fi->next != NULL && fi->next->prev_func.p)
fprintf_unfiltered (file, "0x%s", paddr_nz (fi->next->prev_func.addr));
else
fprintf_unfiltered (file, "<unknown>");
fprintf_unfiltered (file, "}");
}
/* Return a frame uniq ID that can be used to, later, re-find the
frame. */
struct frame_id
get_frame_id (struct frame_info *fi)
{
if (fi == NULL)
{
return null_frame_id;
}
if (!fi->this_id.p)
{
gdb_assert (!legacy_frame_p (current_gdbarch));
if (frame_debug)
fprintf_unfiltered (gdb_stdlog, "{ get_frame_id (fi=%d) ",
fi->level);
/* Find the unwinder. */
if (fi->unwind == NULL)
{
fi->unwind = frame_unwind_find_by_frame (fi->next,
&fi->prologue_cache);
/* FIXME: cagney/2004-05-01: Should instead just use
->unwind->type. Unfortunately, legacy_get_prev_frame is
still explicitly setting the type. Eliminate that method
and this field can be eliminated. */
fi->type = fi->unwind->type;
}
/* Find THIS frame's ID. */
fi->unwind->this_id (fi->next, &fi->prologue_cache, &fi->this_id.value);
fi->this_id.p = 1;
if (frame_debug)
{
fprintf_unfiltered (gdb_stdlog, "-> ");
fprint_frame_id (gdb_stdlog, fi->this_id.value);
fprintf_unfiltered (gdb_stdlog, " }\n");
}
}
return fi->this_id.value;
}
struct frame_id
frame_unwind_id (struct frame_info *next_frame)
{
/* Use prev_frame, and not get_prev_frame. The latter will truncate
the frame chain, leading to this function unintentionally
returning a null_frame_id (e.g., when a caller requests the frame
ID of "main()"s caller. */
return get_frame_id (get_prev_frame_1 (next_frame));
}
const struct frame_id null_frame_id; /* All zeros. */
struct frame_id
frame_id_build_special (CORE_ADDR stack_addr, CORE_ADDR code_addr,
CORE_ADDR special_addr)
{
struct frame_id id;
id.stack_addr = stack_addr;
id.code_addr = code_addr;
id.special_addr = special_addr;
return id;
}
struct frame_id
frame_id_build (CORE_ADDR stack_addr, CORE_ADDR code_addr)
{
return frame_id_build_special (stack_addr, code_addr, 0);
}
int
frame_id_p (struct frame_id l)
{
int p;
/* The .code can be NULL but the .stack cannot. */
p = (l.stack_addr != 0);
if (frame_debug)
{
fprintf_unfiltered (gdb_stdlog, "{ frame_id_p (l=");
fprint_frame_id (gdb_stdlog, l);
fprintf_unfiltered (gdb_stdlog, ") -> %d }\n", p);
}
return p;
}
int
frame_id_eq (struct frame_id l, struct frame_id r)
{
int eq;
if (l.stack_addr == 0 || r.stack_addr == 0)
/* Like a NaN, if either ID is invalid, the result is false. */
eq = 0;
else if (l.stack_addr != r.stack_addr)
/* If .stack addresses are different, the frames are different. */
eq = 0;
else if (l.code_addr == 0 || r.code_addr == 0)
/* A zero code addr is a wild card, always succeed. */
eq = 1;
else if (l.code_addr != r.code_addr)
/* If .code addresses are different, the frames are different. */
eq = 0;
else if (l.special_addr == 0 || r.special_addr == 0)
/* A zero special addr is a wild card (or unused), always succeed. */
eq = 1;
else if (l.special_addr == r.special_addr)
/* Frames are equal. */
eq = 1;
else
/* No luck. */
eq = 0;
if (frame_debug)
{
fprintf_unfiltered (gdb_stdlog, "{ frame_id_eq (l=");
fprint_frame_id (gdb_stdlog, l);
fprintf_unfiltered (gdb_stdlog, ",r=");
fprint_frame_id (gdb_stdlog, r);
fprintf_unfiltered (gdb_stdlog, ") -> %d }\n", eq);
}
return eq;
}
int
frame_id_inner (struct frame_id l, struct frame_id r)
{
int inner;
if (l.stack_addr == 0 || r.stack_addr == 0)
/* Like NaN, any operation involving an invalid ID always fails. */
inner = 0;
else
/* Only return non-zero when strictly inner than. Note that, per
comment in "frame.h", there is some fuzz here. Frameless
functions are not strictly inner than (same .stack but
different .code and/or .special address). */
inner = INNER_THAN (l.stack_addr, r.stack_addr);
if (frame_debug)
{
fprintf_unfiltered (gdb_stdlog, "{ frame_id_inner (l=");
fprint_frame_id (gdb_stdlog, l);
fprintf_unfiltered (gdb_stdlog, ",r=");
fprint_frame_id (gdb_stdlog, r);
fprintf_unfiltered (gdb_stdlog, ") -> %d }\n", inner);
}
return inner;
}
struct frame_info *
frame_find_by_id (struct frame_id id)
{
struct frame_info *frame;
/* ZERO denotes the null frame, let the caller decide what to do
about it. Should it instead return get_current_frame()? */
if (!frame_id_p (id))
return NULL;
for (frame = get_current_frame ();
frame != NULL;
frame = get_prev_frame (frame))
{
struct frame_id this = get_frame_id (frame);
if (frame_id_eq (id, this))
/* An exact match. */
return frame;
if (frame_id_inner (id, this))
/* Gone to far. */
return NULL;
/* Either we're not yet gone far enough out along the frame
chain (inner(this,id)), or we're comparing frameless functions
(same .base, different .func, no test available). Struggle
on until we've definitly gone to far. */
}
return NULL;
}
CORE_ADDR
frame_pc_unwind (struct frame_info *this_frame)
{
if (!this_frame->prev_pc.p)
{
CORE_ADDR pc;
if (gdbarch_unwind_pc_p (current_gdbarch))
{
/* The right way. The `pure' way. The one true way. This
method depends solely on the register-unwind code to
determine the value of registers in THIS frame, and hence
the value of this frame's PC (resume address). A typical
implementation is no more than:
frame_unwind_register (this_frame, ISA_PC_REGNUM, buf);
return extract_unsigned_integer (buf, size of ISA_PC_REGNUM);
Note: this method is very heavily dependent on a correct
register-unwind implementation, it pays to fix that
method first; this method is frame type agnostic, since
it only deals with register values, it works with any
frame. This is all in stark contrast to the old
FRAME_SAVED_PC which would try to directly handle all the
different ways that a PC could be unwound. */
pc = gdbarch_unwind_pc (current_gdbarch, this_frame);
}
else if (this_frame->level < 0)
{
/* FIXME: cagney/2003-03-06: Old code and a sentinel
frame. Do like was always done. Fetch the PC's value
directly from the global registers array (via read_pc).
This assumes that this frame belongs to the current
global register cache. The assumption is dangerous. */
pc = read_pc ();
}
else if (DEPRECATED_FRAME_SAVED_PC_P ())
{
/* FIXME: cagney/2003-03-06: Old code, but not a sentinel
frame. Do like was always done. Note that this method,
unlike unwind_pc(), tries to handle all the different
frame cases directly. It fails. */
pc = DEPRECATED_FRAME_SAVED_PC (this_frame);
}
else
internal_error (__FILE__, __LINE__, "No gdbarch_unwind_pc method");
this_frame->prev_pc.value = pc;
this_frame->prev_pc.p = 1;
if (frame_debug)
fprintf_unfiltered (gdb_stdlog,
"{ frame_pc_unwind (this_frame=%d) -> 0x%s }\n",
this_frame->level,
paddr_nz (this_frame->prev_pc.value));
}
return this_frame->prev_pc.value;
}
CORE_ADDR
frame_func_unwind (struct frame_info *fi)
{
if (!fi->prev_func.p)
{
/* Make certain that this, and not the adjacent, function is
found. */
CORE_ADDR addr_in_block = frame_unwind_address_in_block (fi);
fi->prev_func.p = 1;
fi->prev_func.addr = get_pc_function_start (addr_in_block);
if (frame_debug)
fprintf_unfiltered (gdb_stdlog,
"{ frame_func_unwind (fi=%d) -> 0x%s }\n",
fi->level, paddr_nz (fi->prev_func.addr));
}
return fi->prev_func.addr;
}
CORE_ADDR
get_frame_func (struct frame_info *fi)
{
return frame_func_unwind (fi->next);
}
static int
do_frame_unwind_register (void *src, int regnum, void *buf)
{
frame_unwind_register (src, regnum, buf);
return 1;
}
void
frame_pop (struct frame_info *this_frame)
{
struct regcache *scratch_regcache;
struct cleanup *cleanups;
if (DEPRECATED_POP_FRAME_P ())
{
/* A legacy architecture that has implemented a custom pop
function. All new architectures should instead be using the
generic code below. */
DEPRECATED_POP_FRAME;
}
else
{
/* Make a copy of all the register values unwound from this
frame. Save them in a scratch buffer so that there isn't a
race between trying to extract the old values from the
current_regcache while at the same time writing new values
into that same cache. */
struct regcache *scratch = regcache_xmalloc (current_gdbarch);
struct cleanup *cleanups = make_cleanup_regcache_xfree (scratch);
regcache_save (scratch, do_frame_unwind_register, this_frame);
/* FIXME: cagney/2003-03-16: It should be possible to tell the
target's register cache that it is about to be hit with a
burst register transfer and that the sequence of register
writes should be batched. The pair target_prepare_to_store()
and target_store_registers() kind of suggest this
functionality. Unfortunately, they don't implement it. Their
lack of a formal definition can lead to targets writing back
bogus values (arguably a bug in the target code mind). */
/* Now copy those saved registers into the current regcache.
Here, regcache_cpy() calls regcache_restore(). */
regcache_cpy (current_regcache, scratch);
do_cleanups (cleanups);
}
/* We've made right mess of GDB's local state, just discard
everything. */
flush_cached_frames ();
}
void
frame_register_unwind (struct frame_info *frame, int regnum,
int *optimizedp, enum lval_type *lvalp,
CORE_ADDR *addrp, int *realnump, void *bufferp)
{
struct frame_unwind_cache *cache;
if (frame_debug)
{
fprintf_unfiltered (gdb_stdlog, "\
{ frame_register_unwind (frame=%d,regnum=%d(%s),...) ",
frame->level, regnum,
frame_map_regnum_to_name (frame, regnum));
}
/* Require all but BUFFERP to be valid. A NULL BUFFERP indicates
that the value proper does not need to be fetched. */
gdb_assert (optimizedp != NULL);
gdb_assert (lvalp != NULL);
gdb_assert (addrp != NULL);
gdb_assert (realnump != NULL);
/* gdb_assert (bufferp != NULL); */
/* NOTE: cagney/2002-11-27: A program trying to unwind a NULL frame
is broken. There is always a frame. If there, for some reason,
isn't a frame, there is some pretty busted code as it should have
detected the problem before calling here. */
gdb_assert (frame != NULL);
/* Find the unwinder. */
if (frame->unwind == NULL)
{
frame->unwind = frame_unwind_find_by_frame (frame->next,
&frame->prologue_cache);
/* FIXME: cagney/2004-05-01: Should instead just use ->unwind->type.
Unfortunately, legacy_get_prev_frame is still explicitly setting
the type. Eliminate that method and this field can be
eliminated. */
frame->type = frame->unwind->type;
}
/* Ask this frame to unwind its register. See comment in
"frame-unwind.h" for why NEXT frame and this unwind cache are
passed in. */
frame->unwind->prev_register (frame->next, &frame->prologue_cache, regnum,
optimizedp, lvalp, addrp, realnump, bufferp);
if (frame_debug)
{
fprintf_unfiltered (gdb_stdlog, "->");
fprintf_unfiltered (gdb_stdlog, " *optimizedp=%d", (*optimizedp));
fprintf_unfiltered (gdb_stdlog, " *lvalp=%d", (int) (*lvalp));
fprintf_unfiltered (gdb_stdlog, " *addrp=0x%s", paddr_nz ((*addrp)));
fprintf_unfiltered (gdb_stdlog, " *bufferp=");
if (bufferp == NULL)
fprintf_unfiltered (gdb_stdlog, "<NULL>");
else
{
int i;
const unsigned char *buf = bufferp;
fprintf_unfiltered (gdb_stdlog, "[");
for (i = 0; i < register_size (current_gdbarch, regnum); i++)
fprintf_unfiltered (gdb_stdlog, "%02x", buf[i]);
fprintf_unfiltered (gdb_stdlog, "]");
}
fprintf_unfiltered (gdb_stdlog, " }\n");
}
}
void
frame_register (struct frame_info *frame, int regnum,
int *optimizedp, enum lval_type *lvalp,
CORE_ADDR *addrp, int *realnump, void *bufferp)
{
/* Require all but BUFFERP to be valid. A NULL BUFFERP indicates
that the value proper does not need to be fetched. */
gdb_assert (optimizedp != NULL);
gdb_assert (lvalp != NULL);
gdb_assert (addrp != NULL);
gdb_assert (realnump != NULL);
/* gdb_assert (bufferp != NULL); */
/* Ulgh! Old code that, for lval_register, sets ADDRP to the offset
of the register in the register cache. It should instead return
the REGNUM corresponding to that register. Translate the . */
if (DEPRECATED_GET_SAVED_REGISTER_P ())
{
DEPRECATED_GET_SAVED_REGISTER (bufferp, optimizedp, addrp, frame,
regnum, lvalp);
/* Compute the REALNUM if the caller wants it. */
if (*lvalp == lval_register)
{
int regnum;
for (regnum = 0; regnum < NUM_REGS + NUM_PSEUDO_REGS; regnum++)
{
if (*addrp == register_offset_hack (current_gdbarch, regnum))
{
*realnump = regnum;
return;
}
}
internal_error (__FILE__, __LINE__,
"Failed to compute the register number corresponding"
" to 0x%s", paddr_d (*addrp));
}
*realnump = -1;
return;
}
/* Obtain the register value by unwinding the register from the next
(more inner frame). */
gdb_assert (frame != NULL && frame->next != NULL);
frame_register_unwind (frame->next, regnum, optimizedp, lvalp, addrp,
realnump, bufferp);
}
void
frame_unwind_register (struct frame_info *frame, int regnum, void *buf)
{
int optimized;
CORE_ADDR addr;
int realnum;
enum lval_type lval;
frame_register_unwind (frame, regnum, &optimized, &lval, &addr,
&realnum, buf);
}
void
get_frame_register (struct frame_info *frame,
int regnum, void *buf)
{
frame_unwind_register (frame->next, regnum, buf);
}
LONGEST
frame_unwind_register_signed (struct frame_info *frame, int regnum)
{
char buf[MAX_REGISTER_SIZE];
frame_unwind_register (frame, regnum, buf);
return extract_signed_integer (buf, DEPRECATED_REGISTER_VIRTUAL_SIZE (regnum));
}
LONGEST
get_frame_register_signed (struct frame_info *frame, int regnum)
{
return frame_unwind_register_signed (frame->next, regnum);
}
ULONGEST
frame_unwind_register_unsigned (struct frame_info *frame, int regnum)
{
char buf[MAX_REGISTER_SIZE];
frame_unwind_register (frame, regnum, buf);
return extract_unsigned_integer (buf, DEPRECATED_REGISTER_VIRTUAL_SIZE (regnum));
}
ULONGEST
get_frame_register_unsigned (struct frame_info *frame, int regnum)
{
return frame_unwind_register_unsigned (frame->next, regnum);
}
void
frame_unwind_unsigned_register (struct frame_info *frame, int regnum,
ULONGEST *val)
{
char buf[MAX_REGISTER_SIZE];
frame_unwind_register (frame, regnum, buf);
(*val) = extract_unsigned_integer (buf, DEPRECATED_REGISTER_VIRTUAL_SIZE (regnum));
}
void
put_frame_register (struct frame_info *frame, int regnum, const void *buf)
{
struct gdbarch *gdbarch = get_frame_arch (frame);
int realnum;
int optim;
enum lval_type lval;
CORE_ADDR addr;
frame_register (frame, regnum, &optim, &lval, &addr, &realnum, NULL);
if (optim)
error ("Attempt to assign to a value that was optimized out.");
switch (lval)
{
case lval_memory:
{
/* FIXME: write_memory doesn't yet take constant buffers.
Arrrg! */
char tmp[MAX_REGISTER_SIZE];
memcpy (tmp, buf, register_size (gdbarch, regnum));
write_memory (addr, tmp, register_size (gdbarch, regnum));
break;
}
case lval_register:
regcache_cooked_write (current_regcache, realnum, buf);
break;
default:
error ("Attempt to assign to an unmodifiable value.");
}
}
/* frame_register_read ()
Find and return the value of REGNUM for the specified stack frame.
The number of bytes copied is DEPRECATED_REGISTER_RAW_SIZE
(REGNUM).
Returns 0 if the register value could not be found. */
int
frame_register_read (struct frame_info *frame, int regnum, void *myaddr)
{
int optimized;
enum lval_type lval;
CORE_ADDR addr;
int realnum;
frame_register (frame, regnum, &optimized, &lval, &addr, &realnum, myaddr);
/* FIXME: cagney/2002-05-15: This test is just bogus.
It indicates that the target failed to supply a value for a
register because it was "not available" at this time. Problem
is, the target still has the register and so get saved_register()
may be returning a value saved on the stack. */
if (register_cached (regnum) < 0)
return 0; /* register value not available */
return !optimized;
}
/* Map between a frame register number and its name. A frame register
space is a superset of the cooked register space --- it also
includes builtin registers. */
int
frame_map_name_to_regnum (struct frame_info *frame, const char *name, int len)
{
return user_reg_map_name_to_regnum (get_frame_arch (frame), name, len);
}
const char *
frame_map_regnum_to_name (struct frame_info *frame, int regnum)
{
return user_reg_map_regnum_to_name (get_frame_arch (frame), regnum);
}
/* Create a sentinel frame. */
static struct frame_info *
create_sentinel_frame (struct regcache *regcache)
{
struct frame_info *frame = FRAME_OBSTACK_ZALLOC (struct frame_info);
frame->type = SENTINEL_FRAME;
frame->level = -1;
/* Explicitly initialize the sentinel frame's cache. Provide it
with the underlying regcache. In the future additional
information, such as the frame's thread will be added. */
frame->prologue_cache = sentinel_frame_cache (regcache);
/* For the moment there is only one sentinel frame implementation. */
frame->unwind = sentinel_frame_unwind;
/* Link this frame back to itself. The frame is self referential
(the unwound PC is the same as the pc), so make it so. */
frame->next = frame;
/* Make the sentinel frame's ID valid, but invalid. That way all
comparisons with it should fail. */
frame->this_id.p = 1;
frame->this_id.value = null_frame_id;
if (frame_debug)
{
fprintf_unfiltered (gdb_stdlog, "{ create_sentinel_frame (...) -> ");
fprint_frame (gdb_stdlog, frame);
fprintf_unfiltered (gdb_stdlog, " }\n");
}
return frame;
}
/* Info about the innermost stack frame (contents of FP register) */
static struct frame_info *current_frame;
/* Cache for frame addresses already read by gdb. Valid only while
inferior is stopped. Control variables for the frame cache should
be local to this module. */
static struct obstack frame_cache_obstack;
void *
frame_obstack_zalloc (unsigned long size)
{
void *data = obstack_alloc (&frame_cache_obstack, size);
memset (data, 0, size);
return data;
}
CORE_ADDR *
frame_saved_regs_zalloc (struct frame_info *fi)
{
fi->saved_regs = (CORE_ADDR *)
frame_obstack_zalloc (SIZEOF_FRAME_SAVED_REGS);
return fi->saved_regs;
}
CORE_ADDR *
deprecated_get_frame_saved_regs (struct frame_info *fi)
{
return fi->saved_regs;
}
/* Return the innermost (currently executing) stack frame. This is
split into two functions. The function unwind_to_current_frame()
is wrapped in catch exceptions so that, even when the unwind of the
sentinel frame fails, the function still returns a stack frame. */
static int
unwind_to_current_frame (struct ui_out *ui_out, void *args)
{
struct frame_info *frame = get_prev_frame (args);
/* A sentinel frame can fail to unwind, e.g., because its PC value
lands in somewhere like start. */
if (frame == NULL)
return 1;
current_frame = frame;
return 0;
}
struct frame_info *
get_current_frame (void)
{
/* First check, and report, the lack of registers. Having GDB
report "No stack!" or "No memory" when the target doesn't even
have registers is very confusing. Besides, "printcmd.exp"
explicitly checks that ``print $pc'' with no registers prints "No
registers". */
if (!target_has_registers)
error ("No registers.");
if (!target_has_stack)
error ("No stack.");
if (!target_has_memory)
error ("No memory.");
if (current_frame == NULL)
{
struct frame_info *sentinel_frame =
create_sentinel_frame (current_regcache);
if (catch_exceptions (uiout, unwind_to_current_frame, sentinel_frame,
NULL, RETURN_MASK_ERROR) != 0)
{
/* Oops! Fake a current frame? Is this useful? It has a PC
of zero, for instance. */
current_frame = sentinel_frame;
}
}
return current_frame;
}
/* The "selected" stack frame is used by default for local and arg
access. May be zero, for no selected frame. */
struct frame_info *deprecated_selected_frame;
/* Return the selected frame. Always non-NULL (unless there isn't an
inferior sufficient for creating a frame) in which case an error is
thrown. */
struct frame_info *
get_selected_frame (void)
{
if (deprecated_selected_frame == NULL)
/* Hey! Don't trust this. It should really be re-finding the
last selected frame of the currently selected thread. This,
though, is better than nothing. */
select_frame (get_current_frame ());
/* There is always a frame. */
gdb_assert (deprecated_selected_frame != NULL);
return deprecated_selected_frame;
}
/* This is a variant of get_selected_frame() which can be called when
the inferior does not have a frame; in that case it will return
NULL instead of calling error(). */
struct frame_info *
deprecated_safe_get_selected_frame (void)
{
if (!target_has_registers || !target_has_stack || !target_has_memory)
return NULL;
return get_selected_frame ();
}
/* Select frame FI (or NULL - to invalidate the current frame). */
void
select_frame (struct frame_info *fi)
{
struct symtab *s;
deprecated_selected_frame = fi;
/* NOTE: cagney/2002-05-04: FI can be NULL. This occurs when the
frame is being invalidated. */
if (deprecated_selected_frame_level_changed_hook)
deprecated_selected_frame_level_changed_hook (frame_relative_level (fi));
/* FIXME: kseitz/2002-08-28: It would be nice to call
selected_frame_level_changed_event() right here, but due to limitations
in the current interfaces, we would end up flooding UIs with events
because select_frame() is used extensively internally.
Once we have frame-parameterized frame (and frame-related) commands,
the event notification can be moved here, since this function will only
be called when the user's selected frame is being changed. */
/* Ensure that symbols for this frame are read in. Also, determine the
source language of this frame, and switch to it if desired. */
if (fi)
{
/* We retrieve the frame's symtab by using the frame PC. However
we cannot use the frame PC as-is, because it usually points to
the instruction following the "call", which is sometimes the
first instruction of another function. So we rely on
get_frame_address_in_block() which provides us with a PC which
is guaranteed to be inside the frame's code block. */
s = find_pc_symtab (get_frame_address_in_block (fi));
if (s
&& s->language != current_language->la_language
&& s->language != language_unknown
&& language_mode == language_mode_auto)
{
set_language (s->language);
}
}
}
/* Return the register saved in the simplistic ``saved_regs'' cache.
If the value isn't here AND a value is needed, try the next inner
most frame. */
static void
legacy_saved_regs_prev_register (struct frame_info *next_frame,
void **this_prologue_cache,
int regnum, int *optimizedp,
enum lval_type *lvalp, CORE_ADDR *addrp,
int *realnump, void *bufferp)
{
/* HACK: New code is passed the next frame and this cache.
Unfortunately, old code expects this frame. Since this is a
backward compatibility hack, cheat by walking one level along the
prologue chain to the frame the old code expects.
Do not try this at home. Professional driver, closed course. */
struct frame_info *frame = next_frame->prev;
gdb_assert (frame != NULL);
if (deprecated_get_frame_saved_regs (frame) == NULL)
{
/* If nothing has initialized the saved regs, do it now. */
gdb_assert (DEPRECATED_FRAME_INIT_SAVED_REGS_P ());
DEPRECATED_FRAME_INIT_SAVED_REGS (frame);
gdb_assert (deprecated_get_frame_saved_regs (frame) != NULL);
}
if (deprecated_get_frame_saved_regs (frame) != NULL
&& deprecated_get_frame_saved_regs (frame)[regnum] != 0)
{
if (regnum == SP_REGNUM)
{
/* SP register treated specially. */
*optimizedp = 0;
*lvalp = not_lval;
*addrp = 0;
*realnump = -1;
if (bufferp != NULL)
/* NOTE: cagney/2003-05-09: In-lined store_address() with
it's body - store_unsigned_integer(). */
store_unsigned_integer (bufferp, DEPRECATED_REGISTER_RAW_SIZE (regnum),
deprecated_get_frame_saved_regs (frame)[regnum]);
}
else
{
/* Any other register is saved in memory, fetch it but cache
a local copy of its value. */
*optimizedp = 0;
*lvalp = lval_memory;
*addrp = deprecated_get_frame_saved_regs (frame)[regnum];
*realnump = -1;
if (bufferp != NULL)
{
#if 1
/* Save each register value, as it is read in, in a
frame based cache. */
void **regs = (*this_prologue_cache);
if (regs == NULL)
{
int sizeof_cache = ((NUM_REGS + NUM_PSEUDO_REGS)
* sizeof (void *));
regs = frame_obstack_zalloc (sizeof_cache);
(*this_prologue_cache) = regs;
}
if (regs[regnum] == NULL)
{
regs[regnum]
= frame_obstack_zalloc (DEPRECATED_REGISTER_RAW_SIZE (regnum));
read_memory (deprecated_get_frame_saved_regs (frame)[regnum], regs[regnum],
DEPRECATED_REGISTER_RAW_SIZE (regnum));
}
memcpy (bufferp, regs[regnum], DEPRECATED_REGISTER_RAW_SIZE (regnum));
#else
/* Read the value in from memory. */
read_memory (deprecated_get_frame_saved_regs (frame)[regnum], bufferp,
DEPRECATED_REGISTER_RAW_SIZE (regnum));
#endif
}
}
return;
}
/* No luck. Assume this and the next frame have the same register
value. Pass the unwind request down the frame chain to the next
frame. Hopefully that frame will find the register's location. */
frame_register_unwind (next_frame, regnum, optimizedp, lvalp, addrp,
realnump, bufferp);
}
static void
legacy_saved_regs_this_id (struct frame_info *next_frame,
void **this_prologue_cache,
struct frame_id *id)
{
/* A developer is trying to bring up a new architecture, help them
by providing a default unwinder that refuses to unwind anything
(the ID is always NULL). In the case of legacy code,
legacy_get_prev_frame() will have previously set ->this_id.p, so
this code won't be called. */
(*id) = null_frame_id;
}
const struct frame_unwind legacy_saved_regs_unwinder = {
/* Not really. It gets overridden by legacy_get_prev_frame(). */
UNKNOWN_FRAME,
legacy_saved_regs_this_id,
legacy_saved_regs_prev_register
};
const struct frame_unwind *legacy_saved_regs_unwind = &legacy_saved_regs_unwinder;
/* Determine the frame's type based on its PC. */
static enum frame_type
frame_type_from_pc (CORE_ADDR pc)
{
/* NOTE: cagney/2004-05-08: Eliminating this function depends on all
architectures being forced to use the frame-unwind code. */
if (deprecated_pc_in_call_dummy (pc, 0, 0))
return DUMMY_FRAME;
else
return NORMAL_FRAME;
}
/* Create an arbitrary (i.e. address specified by user) or innermost frame.
Always returns a non-NULL value. */
struct frame_info *
create_new_frame (CORE_ADDR addr, CORE_ADDR pc)
{
struct frame_info *fi;
if (frame_debug)
{
fprintf_unfiltered (gdb_stdlog,
"{ create_new_frame (addr=0x%s, pc=0x%s) ",
paddr_nz (addr), paddr_nz (pc));
}
fi = frame_obstack_zalloc (sizeof (struct frame_info));
fi->next = create_sentinel_frame (current_regcache);
/* Select/initialize both the unwind function and the frame's type
based on the PC. */
fi->unwind = frame_unwind_find_by_frame (fi->next, &fi->prologue_cache);
if (fi->unwind->type != UNKNOWN_FRAME)
fi->type = fi->unwind->type;
else
fi->type = frame_type_from_pc (pc);
fi->this_id.p = 1;
deprecated_update_frame_base_hack (fi, addr);
deprecated_update_frame_pc_hack (fi, pc);
if (DEPRECATED_INIT_EXTRA_FRAME_INFO_P ())
DEPRECATED_INIT_EXTRA_FRAME_INFO (0, fi);
if (frame_debug)
{
fprintf_unfiltered (gdb_stdlog, "-> ");
fprint_frame (gdb_stdlog, fi);
fprintf_unfiltered (gdb_stdlog, " }\n");
}
return fi;
}
/* Return the frame that THIS_FRAME calls (NULL if THIS_FRAME is the
innermost frame). Be careful to not fall off the bottom of the
frame chain and onto the sentinel frame. */
struct frame_info *
get_next_frame (struct frame_info *this_frame)
{
if (this_frame->level > 0)
return this_frame->next;
else
return NULL;
}
/* Observer for the target_changed event. */
void
frame_observer_target_changed (struct target_ops *target)
{
flush_cached_frames ();
}
/* Flush the entire frame cache. */
void
flush_cached_frames (void)
{
/* Since we can't really be sure what the first object allocated was */
obstack_free (&frame_cache_obstack, 0);
obstack_init (&frame_cache_obstack);
current_frame = NULL; /* Invalidate cache */
select_frame (NULL);
annotate_frames_invalid ();
if (frame_debug)
fprintf_unfiltered (gdb_stdlog, "{ flush_cached_frames () }\n");
}
/* Flush the frame cache, and start a new one if necessary. */
void
reinit_frame_cache (void)
{
flush_cached_frames ();
/* FIXME: The inferior_ptid test is wrong if there is a corefile. */
if (PIDGET (inferior_ptid) != 0)
{
select_frame (get_current_frame ());
}
}
/* Create the previous frame using the deprecated methods
INIT_EXTRA_INFO, and INIT_FRAME_PC. */
static struct frame_info *
legacy_get_prev_frame (struct frame_info *this_frame)
{
CORE_ADDR address = 0;
struct frame_info *prev;
int fromleaf;
/* Don't frame_debug print legacy_get_prev_frame() here, just
confuses the output. */
/* Allocate the new frame.
There is no reason to worry about memory leaks, should the
remainder of the function fail. The allocated memory will be
quickly reclaimed when the frame cache is flushed, and the `we've
been here before' check, in get_prev_frame() will stop repeated
memory allocation calls. */
prev = FRAME_OBSTACK_ZALLOC (struct frame_info);
prev->level = this_frame->level + 1;
/* Do not completely wire it in to the frame chain. Some (bad) code
in INIT_FRAME_EXTRA_INFO tries to look along frame->prev to pull
some fancy tricks (of course such code is, by definition,
recursive).
On the other hand, methods, such as get_frame_pc() and
get_frame_base() rely on being able to walk along the frame
chain. Make certain that at least they work by providing that
link. Of course things manipulating prev can't go back. */
prev->next = this_frame;
/* NOTE: cagney/2002-11-18: Should have been correctly setting the
frame's type here, before anything else, and not last, at the
bottom of this function. The various
DEPRECATED_INIT_EXTRA_FRAME_INFO, DEPRECATED_INIT_FRAME_PC, and
DEPRECATED_FRAME_INIT_SAVED_REGS methods are full of work-arounds
that handle the frame not being correctly set from the start.
Unfortunately those same work-arounds rely on the type defaulting
to NORMAL_FRAME. Ulgh! The new frame code does not have this
problem. */
prev->type = UNKNOWN_FRAME;
/* A legacy frame's ID is always computed here. Mark it as valid. */
prev->this_id.p = 1;
/* Handle sentinel frame unwind as a special case. */
if (this_frame->level < 0)
{
/* Try to unwind the PC. If that doesn't work, assume we've reached
the oldest frame and simply return. Is there a better sentinal
value? The unwound PC value is then used to initialize the new
previous frame's type.
Note that the pc-unwind is intentionally performed before the
frame chain. This is ok since, for old targets, both
frame_pc_unwind() (nee, DEPRECATED_FRAME_SAVED_PC) and
DEPRECATED_FRAME_CHAIN()) assume THIS_FRAME's data structures
have already been initialized (using
DEPRECATED_INIT_EXTRA_FRAME_INFO) and hence the call order
doesn't matter.
By unwinding the PC first, it becomes possible to, in the case of
a dummy frame, avoid also unwinding the frame ID. This is
because (well ignoring the PPC) a dummy frame can be located
using THIS_FRAME's frame ID. */
deprecated_update_frame_pc_hack (prev, frame_pc_unwind (this_frame));
if (get_frame_pc (prev) == 0)
{
/* The allocated PREV_FRAME will be reclaimed when the frame
obstack is next purged. */
if (frame_debug)
{
fprintf_unfiltered (gdb_stdlog, "-> ");
fprint_frame (gdb_stdlog, NULL);
fprintf_unfiltered (gdb_stdlog,
" // unwound legacy PC zero }\n");
}
return NULL;
}
/* Set the unwind functions based on that identified PC. Ditto
for the "type" but strongly prefer the unwinder's frame type. */
prev->unwind = frame_unwind_find_by_frame (prev->next,
&prev->prologue_cache);
if (prev->unwind->type == UNKNOWN_FRAME)
prev->type = frame_type_from_pc (get_frame_pc (prev));
else
prev->type = prev->unwind->type;
/* Find the prev's frame's ID. */
if (prev->type == DUMMY_FRAME
&& gdbarch_unwind_dummy_id_p (current_gdbarch))
{
/* When unwinding a normal frame, the stack structure is
determined by analyzing the frame's function's code (be
it using brute force prologue analysis, or the dwarf2
CFI). In the case of a dummy frame, that simply isn't
possible. The The PC is either the program entry point,
or some random address on the stack. Trying to use that
PC to apply standard frame ID unwind techniques is just
asking for trouble. */
/* Use an architecture specific method to extract the prev's
dummy ID from the next frame. Note that this method uses
frame_register_unwind to obtain the register values
needed to determine the dummy frame's ID. */
prev->this_id.value = gdbarch_unwind_dummy_id (current_gdbarch,
this_frame);
}
else
{
/* We're unwinding a sentinel frame, the PC of which is
pointing at a stack dummy. Fake up the dummy frame's ID
using the same sequence as is found a traditional
unwinder. Once all architectures supply the
unwind_dummy_id method, this code can go away. */
prev->this_id.value = frame_id_build (deprecated_read_fp (),
read_pc ());
}
/* Check that the unwound ID is valid. */
if (!frame_id_p (prev->this_id.value))
{
if (frame_debug)
{
fprintf_unfiltered (gdb_stdlog, "-> ");
fprint_frame (gdb_stdlog, NULL);
fprintf_unfiltered (gdb_stdlog,
" // unwound legacy ID invalid }\n");
}
return NULL;
}
/* Check that the new frame isn't inner to (younger, below,
next) the old frame. If that happens the frame unwind is
going backwards. */
/* FIXME: cagney/2003-02-25: Ignore the sentinel frame since
that doesn't have a valid frame ID. Should instead set the
sentinel frame's frame ID to a `sentinel'. Leave it until
after the switch to storing the frame ID, instead of the
frame base, in the frame object. */
/* Link it in. */
this_frame->prev = prev;
/* FIXME: cagney/2002-01-19: This call will go away. Instead of
initializing extra info, all frames will use the frame_cache
(passed to the unwind functions) to store additional frame
info. Unfortunately legacy targets can't use
legacy_get_prev_frame() to unwind the sentinel frame and,
consequently, are forced to take this code path and rely on
the below call to DEPRECATED_INIT_EXTRA_FRAME_INFO to
initialize the inner-most frame. */
if (DEPRECATED_INIT_EXTRA_FRAME_INFO_P ())
{
DEPRECATED_INIT_EXTRA_FRAME_INFO (0, prev);
}
if (prev->type == NORMAL_FRAME)
prev->this_id.value.code_addr
= get_pc_function_start (prev->this_id.value.code_addr);
if (frame_debug)
{
fprintf_unfiltered (gdb_stdlog, "-> ");
fprint_frame (gdb_stdlog, prev);
fprintf_unfiltered (gdb_stdlog, " } // legacy innermost frame\n");
}
return prev;
}
/* This code only works on normal frames. A sentinel frame, where
the level is -1, should never reach this code. */
gdb_assert (this_frame->level >= 0);
/* On some machines it is possible to call a function without
setting up a stack frame for it. On these machines, we
define this macro to take two args; a frameinfo pointer
identifying a frame and a variable to set or clear if it is
or isn't leafless. */
/* Still don't want to worry about this except on the innermost
frame. This macro will set FROMLEAF if THIS_FRAME is a frameless
function invocation. */
if (this_frame->level == 0)
/* FIXME: 2002-11-09: Frameless functions can occur anywhere in
the frame chain, not just the inner most frame! The generic,
per-architecture, frame code should handle this and the below
should simply be removed. */
fromleaf = (DEPRECATED_FRAMELESS_FUNCTION_INVOCATION_P ()
&& DEPRECATED_FRAMELESS_FUNCTION_INVOCATION (this_frame));
else
fromleaf = 0;
if (fromleaf)
/* A frameless inner-most frame. The `FP' (which isn't an
architecture frame-pointer register!) of the caller is the same
as the callee. */
/* FIXME: 2002-11-09: There isn't any reason to special case this
edge condition. Instead the per-architecture code should handle
it locally. */
/* FIXME: cagney/2003-06-16: This returns the inner most stack
address for the previous frame, that, however, is wrong. It
should be the inner most stack address for the previous to
previous frame. This is because it is the previous to previous
frame's innermost stack address that is constant through out
the lifetime of the previous frame (trust me :-). */
address = get_frame_base (this_frame);
else
{
/* Two macros defined in tm.h specify the machine-dependent
actions to be performed here.
First, get the frame's chain-pointer.
If that is zero, the frame is the outermost frame or a leaf
called by the outermost frame. This means that if start
calls main without a frame, we'll return 0 (which is fine
anyway).
Nope; there's a problem. This also returns when the current
routine is a leaf of main. This is unacceptable. We move
this to after the ffi test; I'd rather have backtraces from
start go curfluy than have an abort called from main not show
main. */
if (DEPRECATED_FRAME_CHAIN_P ())
address = DEPRECATED_FRAME_CHAIN (this_frame);
else
{
/* Someone is part way through coverting an old architecture
to the new frame code. Implement FRAME_CHAIN the way the
new frame will. */
/* Find PREV frame's unwinder. */
prev->unwind = frame_unwind_find_by_frame (this_frame,
&prev->prologue_cache);
/* FIXME: cagney/2004-05-01: Should instead just use
->unwind->type. Unfortunately, legacy_get_prev_frame is
still explicitly setting the type. Eliminate that method
and this field can be eliminated. */
prev->type = prev->unwind->type;
/* Find PREV frame's ID. */
prev->unwind->this_id (this_frame,
&prev->prologue_cache,
&prev->this_id.value);
prev->this_id.p = 1;
address = prev->this_id.value.stack_addr;
}
if (!legacy_frame_chain_valid (address, this_frame))
{
if (frame_debug)
{
fprintf_unfiltered (gdb_stdlog, "-> ");
fprint_frame (gdb_stdlog, NULL);
fprintf_unfiltered (gdb_stdlog,
" // legacy frame chain invalid }\n");
}
return NULL;
}
}
if (address == 0)
{
if (frame_debug)
{
fprintf_unfiltered (gdb_stdlog, "-> ");
fprint_frame (gdb_stdlog, NULL);
fprintf_unfiltered (gdb_stdlog,
" // legacy frame chain NULL }\n");
}
return NULL;
}
/* Link in the already allocated prev frame. */
this_frame->prev = prev;
deprecated_update_frame_base_hack (prev, address);
/* This change should not be needed, FIXME! We should determine
whether any targets *need* DEPRECATED_INIT_FRAME_PC to happen
after DEPRECATED_INIT_EXTRA_FRAME_INFO and come up with a simple
way to express what goes on here.
DEPRECATED_INIT_EXTRA_FRAME_INFO is called from two places:
create_new_frame (where the PC is already set up) and here (where
it isn't). DEPRECATED_INIT_FRAME_PC is only called from here,
always after DEPRECATED_INIT_EXTRA_FRAME_INFO.
The catch is the MIPS, where DEPRECATED_INIT_EXTRA_FRAME_INFO
requires the PC value (which hasn't been set yet). Some other
machines appear to require DEPRECATED_INIT_EXTRA_FRAME_INFO
before they can do DEPRECATED_INIT_FRAME_PC. Phoo.
Assuming that some machines need DEPRECATED_INIT_FRAME_PC after
DEPRECATED_INIT_EXTRA_FRAME_INFO, one possible scheme:
SETUP_INNERMOST_FRAME(): Default version is just create_new_frame
(deprecated_read_fp ()), read_pc ()). Machines with extra frame
info would do that (or the local equivalent) and then set the
extra fields.
SETUP_ARBITRARY_FRAME(argc, argv): Only change here is that
create_new_frame would no longer init extra frame info;
SETUP_ARBITRARY_FRAME would have to do that.
INIT_PREV_FRAME(fromleaf, prev) Replace
DEPRECATED_INIT_EXTRA_FRAME_INFO and DEPRECATED_INIT_FRAME_PC.
This should also return a flag saying whether to keep the new
frame, or whether to discard it, because on some machines (e.g.
mips) it is really awkward to have DEPRECATED_FRAME_CHAIN_VALID
called BEFORE DEPRECATED_INIT_EXTRA_FRAME_INFO (there is no good
way to get information deduced in DEPRECATED_FRAME_CHAIN_VALID
into the extra fields of the new frame). std_frame_pc(fromleaf,
prev)
This is the default setting for INIT_PREV_FRAME. It just does
what the default DEPRECATED_INIT_FRAME_PC does. Some machines
will call it from INIT_PREV_FRAME (either at the beginning, the
end, or in the middle). Some machines won't use it.
kingdon@cygnus.com, 13Apr93, 31Jan94, 14Dec94. */
/* NOTE: cagney/2002-11-09: Just ignore the above! There is no
reason for things to be this complicated.
The trick is to assume that there is always a frame. Instead of
special casing the inner-most frame, create a fake frame
(containing the hardware registers) that is inner to the
user-visible inner-most frame (...) and then unwind from that.
That way architecture code can use the standard
frame_XX_unwind() functions and not differentiate between the
inner most and any other case.
Since there is always a frame to unwind from, there is always
somewhere (THIS_FRAME) to store all the info needed to construct
a new (previous) frame without having to first create it. This
means that the convolution below - needing to carefully order a
frame's initialization - isn't needed.
The irony here though, is that DEPRECATED_FRAME_CHAIN(), at least
for a more up-to-date architecture, always calls
FRAME_SAVED_PC(), and FRAME_SAVED_PC() computes the PC but
without first needing the frame! Instead of the convolution
below, we could have simply called FRAME_SAVED_PC() and been done
with it! Note that FRAME_SAVED_PC() is being superseded by
frame_pc_unwind() and that function does have somewhere to cache
that PC value. */
if (DEPRECATED_INIT_EXTRA_FRAME_INFO_P ())
DEPRECATED_INIT_EXTRA_FRAME_INFO (fromleaf, prev);
/* This entry is in the frame queue now, which is good since
FRAME_SAVED_PC may use that queue to figure out its value (see
tm-sparc.h). We want the PC saved in the inferior frame. */
if (DEPRECATED_INIT_FRAME_PC_P ())
deprecated_update_frame_pc_hack (prev,
DEPRECATED_INIT_FRAME_PC (fromleaf,
prev));
/* If ->frame and ->pc are unchanged, we are in the process of
getting ourselves into an infinite backtrace. Some architectures
check this in DEPRECATED_FRAME_CHAIN or thereabouts, but it seems
like there is no reason this can't be an architecture-independent
check. */
if (get_frame_base (prev) == get_frame_base (this_frame)
&& get_frame_pc (prev) == get_frame_pc (this_frame))
{
this_frame->prev = NULL;
obstack_free (&frame_cache_obstack, prev);
if (frame_debug)
{
fprintf_unfiltered (gdb_stdlog, "-> ");
fprint_frame (gdb_stdlog, NULL);
fprintf_unfiltered (gdb_stdlog,
" // legacy this.id == prev.id }\n");
}
return NULL;
}
/* Initialize the code used to unwind the frame PREV based on the PC
(and probably other architectural information). The PC lets you
check things like the debug info at that point (dwarf2cfi?) and
use that to decide how the frame should be unwound.
If there isn't a FRAME_CHAIN, the code above will have already
done this. */
if (prev->unwind == NULL)
prev->unwind = frame_unwind_find_by_frame (prev->next,
&prev->prologue_cache);
/* If the unwinder provides a frame type, use it. Otherwise
continue on to that heuristic mess. */
if (prev->unwind->type != UNKNOWN_FRAME)
{
prev->type = prev->unwind->type;
if (prev->type == NORMAL_FRAME)
/* FIXME: cagney/2003-06-16: would get_frame_pc() be better? */
prev->this_id.value.code_addr
= get_pc_function_start (prev->this_id.value.code_addr);
if (frame_debug)
{
fprintf_unfiltered (gdb_stdlog, "-> ");
fprint_frame (gdb_stdlog, prev);
fprintf_unfiltered (gdb_stdlog, " } // legacy with unwound type\n");
}
return prev;
}
/* NOTE: cagney/2002-11-18: The code segments, found in
create_new_frame() and get_prev_frame(), that initialize the
frame's type is subtly different. The latter only updates ->type
when it encounters a SIGTRAMP_FRAME or DUMMY_FRAME. This stops
get_prev_frame() overriding the frame's type when the INIT code
has previously set it. This is really somewhat bogus. The
initialization, as seen in create_new_frame(), should occur
before the INIT function has been called. */
if (deprecated_pc_in_call_dummy (get_frame_pc (prev), 0, 0))
prev->type = DUMMY_FRAME;
if (prev->type == NORMAL_FRAME)
prev->this_id.value.code_addr
= get_pc_function_start (prev->this_id.value.code_addr);
if (frame_debug)
{
fprintf_unfiltered (gdb_stdlog, "-> ");
fprint_frame (gdb_stdlog, prev);
fprintf_unfiltered (gdb_stdlog, " } // legacy with confused type\n");
}
return prev;
}
/* Return a "struct frame_info" corresponding to the frame that called
THIS_FRAME. Returns NULL if there is no such frame.
Unlike get_prev_frame, this function always tries to unwind the
frame. */
static struct frame_info *
get_prev_frame_1 (struct frame_info *this_frame)
{
struct frame_info *prev_frame;
struct frame_id this_id;
gdb_assert (this_frame != NULL);
if (frame_debug)
{
fprintf_unfiltered (gdb_stdlog, "{ get_prev_frame_1 (this_frame=");
if (this_frame != NULL)
fprintf_unfiltered (gdb_stdlog, "%d", this_frame->level);
else
fprintf_unfiltered (gdb_stdlog, "<NULL>");
fprintf_unfiltered (gdb_stdlog, ") ");
}
/* Only try to do the unwind once. */
if (this_frame->prev_p)
{
if (frame_debug)
{
fprintf_unfiltered (gdb_stdlog, "-> ");
fprint_frame (gdb_stdlog, this_frame->prev);
fprintf_unfiltered (gdb_stdlog, " // cached \n");
}
return this_frame->prev;
}
this_frame->prev_p = 1;
/* If any of the old frame initialization methods are around, use
the legacy get_prev_frame() method. */
if (legacy_frame_p (current_gdbarch))
{
prev_frame = legacy_get_prev_frame (this_frame);
return prev_frame;
}
/* Check that this frame's ID was valid. If it wasn't, don't try to
unwind to the prev frame. Be careful to not apply this test to
the sentinel frame. */
this_id = get_frame_id (this_frame);
if (this_frame->level >= 0 && !frame_id_p (this_id))
{
if (frame_debug)
{
fprintf_unfiltered (gdb_stdlog, "-> ");
fprint_frame (gdb_stdlog, NULL);
fprintf_unfiltered (gdb_stdlog, " // this ID is NULL }\n");
}
return NULL;
}
/* Check that this frame's ID isn't inner to (younger, below, next)
the next frame. This happens when a frame unwind goes backwards.
Exclude signal trampolines (due to sigaltstack the frame ID can
go backwards) and sentinel frames (the test is meaningless). */
if (this_frame->next->level >= 0
&& this_frame->next->type != SIGTRAMP_FRAME
&& frame_id_inner (this_id, get_frame_id (this_frame->next)))
error ("Previous frame inner to this frame (corrupt stack?)");
/* Check that this and the next frame are not identical. If they
are, there is most likely a stack cycle. As with the inner-than
test above, avoid comparing the inner-most and sentinel frames. */
if (this_frame->level > 0
&& frame_id_eq (this_id, get_frame_id (this_frame->next)))
error ("Previous frame identical to this frame (corrupt stack?)");
/* Allocate the new frame but do not wire it in to the frame chain.
Some (bad) code in INIT_FRAME_EXTRA_INFO tries to look along
frame->next to pull some fancy tricks (of course such code is, by
definition, recursive). Try to prevent it.
There is no reason to worry about memory leaks, should the
remainder of the function fail. The allocated memory will be
quickly reclaimed when the frame cache is flushed, and the `we've
been here before' check above will stop repeated memory
allocation calls. */
prev_frame = FRAME_OBSTACK_ZALLOC (struct frame_info);
prev_frame->level = this_frame->level + 1;
/* Don't yet compute ->unwind (and hence ->type). It is computed
on-demand in get_frame_type, frame_register_unwind, and
get_frame_id. */
/* Don't yet compute the frame's ID. It is computed on-demand by
get_frame_id(). */
/* The unwound frame ID is validate at the start of this function,
as part of the logic to decide if that frame should be further
unwound, and not here while the prev frame is being created.
Doing this makes it possible for the user to examine a frame that
has an invalid frame ID.
Some very old VAX code noted: [...] For the sake of argument,
suppose that the stack is somewhat trashed (which is one reason
that "info frame" exists). So, return 0 (indicating we don't
know the address of the arglist) if we don't know what frame this
frame calls. */
/* Link it in. */
this_frame->prev = prev_frame;
prev_frame->next = this_frame;
if (frame_debug)
{
fprintf_unfiltered (gdb_stdlog, "-> ");
fprint_frame (gdb_stdlog, prev_frame);
fprintf_unfiltered (gdb_stdlog, " }\n");
}
return prev_frame;
}
/* Debug routine to print a NULL frame being returned. */
static void
frame_debug_got_null_frame (struct ui_file *file,
struct frame_info *this_frame,
const char *reason)
{
if (frame_debug)
{
fprintf_unfiltered (gdb_stdlog, "{ get_prev_frame (this_frame=");
if (this_frame != NULL)
fprintf_unfiltered (gdb_stdlog, "%d", this_frame->level);
else
fprintf_unfiltered (gdb_stdlog, "<NULL>");
fprintf_unfiltered (gdb_stdlog, ") -> // %s}\n", reason);
}
}
/* Return a structure containing various interesting information about
the frame that called THIS_FRAME. Returns NULL if there is entier
no such frame or the frame fails any of a set of target-independent
condition that should terminate the frame chain (e.g., as unwinding
past main()).
This function should not contain target-dependent tests, such as
checking whether the program-counter is zero. */
struct frame_info *
get_prev_frame (struct frame_info *this_frame)
{
struct frame_info *prev_frame;
/* Return the inner-most frame, when the caller passes in NULL. */
/* NOTE: cagney/2002-11-09: Not sure how this would happen. The
caller should have previously obtained a valid frame using
get_selected_frame() and then called this code - only possibility
I can think of is code behaving badly.
NOTE: cagney/2003-01-10: Talk about code behaving badly. Check
block_innermost_frame(). It does the sequence: frame = NULL;
while (1) { frame = get_prev_frame (frame); .... }. Ulgh! Why
it couldn't be written better, I don't know.
NOTE: cagney/2003-01-11: I suspect what is happening in
block_innermost_frame() is, when the target has no state
(registers, memory, ...), it is still calling this function. The
assumption being that this function will return NULL indicating
that a frame isn't possible, rather than checking that the target
has state and then calling get_current_frame() and
get_prev_frame(). This is a guess mind. */
if (this_frame == NULL)
{
/* NOTE: cagney/2002-11-09: There was a code segment here that
would error out when CURRENT_FRAME was NULL. The comment
that went with it made the claim ...
``This screws value_of_variable, which just wants a nice
clean NULL return from block_innermost_frame if there are no
frames. I don't think I've ever seen this message happen
otherwise. And returning NULL here is a perfectly legitimate
thing to do.''
Per the above, this code shouldn't even be called with a NULL
THIS_FRAME. */
frame_debug_got_null_frame (gdb_stdlog, this_frame, "this_frame NULL");
return current_frame;
}
/* There is always a frame. If this assertion fails, suspect that
something should be calling get_selected_frame() or
get_current_frame(). */
gdb_assert (this_frame != NULL);
/* Make sure we pass an address within THIS_FRAME's code block to
inside_main_func(). Otherwise, we might stop unwinding at a
function which has a call instruction as its last instruction if
that function immediately precedes main(). */
if (this_frame->level >= 0
&& !backtrace_past_main
&& inside_main_func (get_frame_address_in_block (this_frame)))
/* Don't unwind past main(), but always unwind the sentinel frame.
Note, this is done _before_ the frame has been marked as
previously unwound. That way if the user later decides to
allow unwinds past main(), that just happens. */
{
frame_debug_got_null_frame (gdb_stdlog, this_frame, "inside main func");
return NULL;
}
if (this_frame->level > backtrace_limit)
{
error ("Backtrace limit of %d exceeded", backtrace_limit);
}
/* If we're already inside the entry function for the main objfile,
then it isn't valid. Don't apply this test to a dummy frame -
dummy frame PCs typically land in the entry func. Don't apply
this test to the sentinel frame. Sentinel frames should always
be allowed to unwind. */
/* NOTE: cagney/2003-02-25: Don't enable until someone has found
hard evidence that this is needed. */
/* NOTE: cagney/2003-07-07: Fixed a bug in inside_main_func() -
wasn't checking for "main" in the minimal symbols. With that
fixed asm-source tests now stop in "main" instead of halting the
backtrace in weird and wonderful ways somewhere inside the entry
file. Suspect that tests for inside the entry file/func were
added to work around that (now fixed) case. */
/* NOTE: cagney/2003-07-15: danielj (if I'm reading it right)
suggested having the inside_entry_func test use the
inside_main_func() msymbol trick (along with entry_point_address()
I guess) to determine the address range of the start function.
That should provide a far better stopper than the current
heuristics. */
/* NOTE: cagney/2003-07-15: Need to add a "set backtrace
beyond-entry-func" command so that this can be selectively
disabled. */
if (0
#if 0
&& backtrace_beyond_entry_func
#endif
&& this_frame->type != DUMMY_FRAME && this_frame->level >= 0
&& inside_entry_func (this_frame))
{
frame_debug_got_null_frame (gdb_stdlog, this_frame, "inside entry func");
return NULL;
}
return get_prev_frame_1 (this_frame);
}
CORE_ADDR
get_frame_pc (struct frame_info *frame)
{
gdb_assert (frame->next != NULL);
return frame_pc_unwind (frame->next);
}
/* Return an address of that falls within the frame's code block. */
CORE_ADDR
frame_unwind_address_in_block (struct frame_info *next_frame)
{
/* A draft address. */
CORE_ADDR pc = frame_pc_unwind (next_frame);
/* If THIS frame is not inner most (i.e., NEXT isn't the sentinel),
and NEXT is `normal' (i.e., not a sigtramp, dummy, ....) THIS
frame's PC ends up pointing at the instruction fallowing the
"call". Adjust that PC value so that it falls on the call
instruction (which, hopefully, falls within THIS frame's code
block. So far it's proved to be a very good approximation. See
get_frame_type() for why ->type can't be used. */
if (next_frame->level >= 0
&& get_frame_type (next_frame) == NORMAL_FRAME)
--pc;
return pc;
}
CORE_ADDR
get_frame_address_in_block (struct frame_info *this_frame)
{
return frame_unwind_address_in_block (this_frame->next);
}
static int
pc_notcurrent (struct frame_info *frame)
{
/* If FRAME is not the innermost frame, that normally means that
FRAME->pc points at the return instruction (which is *after* the
call instruction), and we want to get the line containing the
call (because the call is where the user thinks the program is).
However, if the next frame is either a SIGTRAMP_FRAME or a
DUMMY_FRAME, then the next frame will contain a saved interrupt
PC and such a PC indicates the current (rather than next)
instruction/line, consequently, for such cases, want to get the
line containing fi->pc. */
struct frame_info *next = get_next_frame (frame);
int notcurrent = (next != NULL && get_frame_type (next) == NORMAL_FRAME);
return notcurrent;
}
void
find_frame_sal (struct frame_info *frame, struct symtab_and_line *sal)
{
(*sal) = find_pc_line (get_frame_pc (frame), pc_notcurrent (frame));
}
/* Per "frame.h", return the ``address'' of the frame. Code should
really be using get_frame_id(). */
CORE_ADDR
get_frame_base (struct frame_info *fi)
{
return get_frame_id (fi).stack_addr;
}
/* High-level offsets into the frame. Used by the debug info. */
CORE_ADDR
get_frame_base_address (struct frame_info *fi)
{
if (get_frame_type (fi) != NORMAL_FRAME)
return 0;
if (fi->base == NULL)
fi->base = frame_base_find_by_frame (fi->next);
/* Sneaky: If the low-level unwind and high-level base code share a
common unwinder, let them share the prologue cache. */
if (fi->base->unwind == fi->unwind)
return fi->base->this_base (fi->next, &fi->prologue_cache);
return fi->base->this_base (fi->next, &fi->base_cache);
}
CORE_ADDR
get_frame_locals_address (struct frame_info *fi)
{
void **cache;
if (get_frame_type (fi) != NORMAL_FRAME)
return 0;
/* If there isn't a frame address method, find it. */
if (fi->base == NULL)
fi->base = frame_base_find_by_frame (fi->next);
/* Sneaky: If the low-level unwind and high-level base code share a
common unwinder, let them share the prologue cache. */
if (fi->base->unwind == fi->unwind)
cache = &fi->prologue_cache;
else
cache = &fi->base_cache;
return fi->base->this_locals (fi->next, cache);
}
CORE_ADDR
get_frame_args_address (struct frame_info *fi)
{
void **cache;
if (get_frame_type (fi) != NORMAL_FRAME)
return 0;
/* If there isn't a frame address method, find it. */
if (fi->base == NULL)
fi->base = frame_base_find_by_frame (fi->next);
/* Sneaky: If the low-level unwind and high-level base code share a
common unwinder, let them share the prologue cache. */
if (fi->base->unwind == fi->unwind)
cache = &fi->prologue_cache;
else
cache = &fi->base_cache;
return fi->base->this_args (fi->next, cache);
}
/* Level of the selected frame: 0 for innermost, 1 for its caller, ...
or -1 for a NULL frame. */
int
frame_relative_level (struct frame_info *fi)
{
if (fi == NULL)
return -1;
else
return fi->level;
}
enum frame_type
get_frame_type (struct frame_info *frame)
{
/* Some legacy code, e.g, mips_init_extra_frame_info() wants
to determine the frame's type prior to it being completely
initialized. Don't attempt to lazily initialize ->unwind for
legacy code. It will be initialized in legacy_get_prev_frame(). */
if (frame->unwind == NULL && !legacy_frame_p (current_gdbarch))
{
/* Initialize the frame's unwinder because that's what
provides the frame's type. */
frame->unwind = frame_unwind_find_by_frame (frame->next,
&frame->prologue_cache);
/* FIXME: cagney/2004-05-01: Should instead just use
->unwind->type. Unfortunately, legacy_get_prev_frame is
still explicitly setting the type. Eliminate that method and
this field can be eliminated. */
frame->type = frame->unwind->type;
}
if (frame->type == UNKNOWN_FRAME)
return NORMAL_FRAME;
else
return frame->type;
}
struct frame_extra_info *
get_frame_extra_info (struct frame_info *fi)
{
return fi->extra_info;
}
struct frame_extra_info *
frame_extra_info_zalloc (struct frame_info *fi, long size)
{
fi->extra_info = frame_obstack_zalloc (size);
return fi->extra_info;
}
void
deprecated_update_frame_pc_hack (struct frame_info *frame, CORE_ADDR pc)
{
if (frame_debug)
fprintf_unfiltered (gdb_stdlog,
"{ deprecated_update_frame_pc_hack (frame=%d,pc=0x%s) }\n",
frame->level, paddr_nz (pc));
/* NOTE: cagney/2003-03-11: Some architectures (e.g., Arm) are
maintaining a locally allocated frame object. Since such frames
are not in the frame chain, it isn't possible to assume that the
frame has a next. Sigh. */
if (frame->next != NULL)
{
/* While we're at it, update this frame's cached PC value, found
in the next frame. Oh for the day when "struct frame_info"
is opaque and this hack on hack can just go away. */
frame->next->prev_pc.value = pc;
frame->next->prev_pc.p = 1;
}
}
void
deprecated_update_frame_base_hack (struct frame_info *frame, CORE_ADDR base)
{
if (frame_debug)
fprintf_unfiltered (gdb_stdlog,
"{ deprecated_update_frame_base_hack (frame=%d,base=0x%s) }\n",
frame->level, paddr_nz (base));
/* See comment in "frame.h". */
frame->this_id.value.stack_addr = base;
}
struct frame_info *
deprecated_frame_xmalloc_with_cleanup (long sizeof_saved_regs,
long sizeof_extra_info)
{
struct frame_info *frame = XMALLOC (struct frame_info);
memset (frame, 0, sizeof (*frame));
frame->this_id.p = 1;
make_cleanup (xfree, frame);
if (sizeof_saved_regs > 0)
{
frame->saved_regs = xcalloc (1, sizeof_saved_regs);
make_cleanup (xfree, frame->saved_regs);
}
if (sizeof_extra_info > 0)
{
frame->extra_info = xcalloc (1, sizeof_extra_info);
make_cleanup (xfree, frame->extra_info);
}
return frame;
}
/* Memory access methods. */
void
get_frame_memory (struct frame_info *this_frame, CORE_ADDR addr, void *buf,
int len)
{
read_memory (addr, buf, len);
}
LONGEST
get_frame_memory_signed (struct frame_info *this_frame, CORE_ADDR addr,
int len)
{
return read_memory_integer (addr, len);
}
ULONGEST
get_frame_memory_unsigned (struct frame_info *this_frame, CORE_ADDR addr,
int len)
{
return read_memory_unsigned_integer (addr, len);
}
int
safe_frame_unwind_memory (struct frame_info *this_frame,
CORE_ADDR addr, void *buf, int len)
{
/* NOTE: read_memory_nobpt returns zero on success! */
return !read_memory_nobpt (addr, buf, len);
}
/* Architecture method. */
struct gdbarch *
get_frame_arch (struct frame_info *this_frame)
{
return current_gdbarch;
}
/* Stack pointer methods. */
CORE_ADDR
get_frame_sp (struct frame_info *this_frame)
{
return frame_sp_unwind (this_frame->next);
}
CORE_ADDR
frame_sp_unwind (struct frame_info *next_frame)
{
/* Normality - an architecture that provides a way of obtaining any
frame inner-most address. */
if (gdbarch_unwind_sp_p (current_gdbarch))
return gdbarch_unwind_sp (current_gdbarch, next_frame);
/* Things are looking grim. If it's the inner-most frame and there
is a TARGET_READ_SP, then that can be used. */
if (next_frame->level < 0 && TARGET_READ_SP_P ())
return TARGET_READ_SP ();
/* Now things are really are grim. Hope that the value returned by
the SP_REGNUM register is meaningful. */
if (SP_REGNUM >= 0)
{
ULONGEST sp;
frame_unwind_unsigned_register (next_frame, SP_REGNUM, &sp);
return sp;
}
internal_error (__FILE__, __LINE__, "Missing unwind SP method");
}
int
legacy_frame_p (struct gdbarch *current_gdbarch)
{
if (DEPRECATED_INIT_FRAME_PC_P ()
|| DEPRECATED_INIT_EXTRA_FRAME_INFO_P ()
|| DEPRECATED_FRAME_CHAIN_P ())
/* No question, it's a legacy frame. */
return 1;
if (gdbarch_unwind_dummy_id_p (current_gdbarch))
/* No question, it's not a legacy frame (provided none of the
deprecated methods checked above are present that is). */
return 0;
if (DEPRECATED_TARGET_READ_FP_P ()
|| DEPRECATED_FP_REGNUM >= 0)
/* Assume it's legacy. If you're trying to convert a legacy frame
target to the new mechanism, get rid of these. legacy
get_prev_frame() requires these when unwind_frame_id() isn't
available. */
return 1;
/* Default to assuming that it's brand new code, and hence not
legacy. Force it down the non-legacy path so that the new code
uses the new frame mechanism from day one. Dummy frames won't
work very well but we can live with that. */
return 0;
}
extern initialize_file_ftype _initialize_frame; /* -Wmissing-prototypes */
static struct cmd_list_element *set_backtrace_cmdlist;
static struct cmd_list_element *show_backtrace_cmdlist;
static void
set_backtrace_cmd (char *args, int from_tty)
{
help_list (set_backtrace_cmdlist, "set backtrace ", -1, gdb_stdout);
}
static void
show_backtrace_cmd (char *args, int from_tty)
{
cmd_show_list (show_backtrace_cmdlist, from_tty, "");
}
void
_initialize_frame (void)
{
obstack_init (&frame_cache_obstack);
observer_attach_target_changed (frame_observer_target_changed);
add_prefix_cmd ("backtrace", class_maintenance, set_backtrace_cmd, "\
Set backtrace specific variables.\n\
Configure backtrace variables such as the backtrace limit",
&set_backtrace_cmdlist, "set backtrace ",
0/*allow-unknown*/, &setlist);
add_prefix_cmd ("backtrace", class_maintenance, show_backtrace_cmd, "\
Show backtrace specific variables\n\
Show backtrace variables such as the backtrace limit",
&show_backtrace_cmdlist, "show backtrace ",
0/*allow-unknown*/, &showlist);
add_setshow_boolean_cmd ("past-main", class_obscure,
&backtrace_past_main, "\
Set whether backtraces should continue past \"main\".\n\
Normally the caller of \"main\" is not of interest, so GDB will terminate\n\
the backtrace at \"main\". Set this variable if you need to see the rest\n\
of the stack trace.", "\
Show whether backtraces should continue past \"main\".\n\
Normally the caller of \"main\" is not of interest, so GDB will terminate\n\
the backtrace at \"main\". Set this variable if you need to see the rest\n\
of the stack trace.",
NULL, NULL, &set_backtrace_cmdlist,
&show_backtrace_cmdlist);
add_setshow_uinteger_cmd ("limit", class_obscure,
&backtrace_limit, "\
Set an upper bound on the number of backtrace levels.\n\
No more than the specified number of frames can be displayed or examined.\n\
Zero is unlimited.", "\
Show the upper bound on the number of backtrace levels.",
NULL, NULL, &set_backtrace_cmdlist,
&show_backtrace_cmdlist);
/* Debug this files internals. */
add_show_from_set (add_set_cmd ("frame", class_maintenance, var_zinteger,
&frame_debug, "Set frame debugging.\n\
When non-zero, frame specific internal debugging is enabled.", &setdebuglist),
&showdebuglist);
}
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