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binutils-gdb/gdb/frame.c
Andrew Cagney 270c3b1dfa 2003-03-25 Andrew Cagney <cagney@redhat.com> 
* frame.c (get_prev_frame): Delay validating a frame's ID -
	non-NULL, didn't go backwards - until an attempt to unwind it to
	the previous frame.
2003-03-26 00:00:07 +00:00

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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 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 "builtin-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 "command.h"
#include "gdbcmd.h"
/* Flag to control debugging. */
static int frame_debug;
/* Flag to indicate whether backtraces should stop at main. */
static int backtrace_below_main;
/* 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;
}
else
{
struct frame_id id;
id.base = fi->frame;
id.pc = fi->pc;
return id;
}
}
const struct frame_id null_frame_id; /* All zeros. */
struct frame_id
frame_id_build (CORE_ADDR base, CORE_ADDR func_or_pc)
{
struct frame_id id;
id.base = base;
id.pc = func_or_pc;
return id;
}
int
frame_id_p (struct frame_id l)
{
/* The .func can be NULL but the .base cannot. */
return (l.base != 0);
}
int
frame_id_eq (struct frame_id l, struct frame_id r)
{
/* If .base is different, the frames are different. */
if (l.base != r.base)
return 0;
/* Add a test to check that the frame ID's are for the same function
here. */
return 1;
}
int
frame_id_inner (struct frame_id l, struct frame_id r)
{
/* 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 .base but different
.func). */
return INNER_THAN (l.base, r.base);
}
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->pc_unwind_cache_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_address (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 and a sentinel
frame. Do like was always done. Fetch the PC's value
direct 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->pc_unwind_cache = pc;
this_frame->pc_unwind_cache_p = 1;
}
return this_frame->pc_unwind_cache;
}
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 betweening 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. Unfortunatly, 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;
/* 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, there is some pretty busted code as it should have
detected the problem before calling here. */
gdb_assert (frame != NULL);
/* Ask this frame to unwind its register. See comment in
"frame-unwind.h" for why NEXT frame and this unwind cace are
passed in. */
frame->unwind->prev_register (frame->next, &frame->prologue_cache, regnum,
optimizedp, lvalp, addrp, realnump, bufferp);
}
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
frame_unwind_signed_register (struct frame_info *frame, int regnum,
LONGEST *val)
{
void *buf = alloca (MAX_REGISTER_RAW_SIZE);
frame_unwind_register (frame, regnum, buf);
(*val) = extract_signed_integer (buf, REGISTER_VIRTUAL_SIZE (regnum));
}
void
frame_unwind_unsigned_register (struct frame_info *frame, int regnum,
ULONGEST *val)
{
void *buf = alloca (MAX_REGISTER_RAW_SIZE);
frame_unwind_register (frame, regnum, buf);
(*val) = extract_unsigned_integer (buf, REGISTER_VIRTUAL_SIZE (regnum));
}
void
frame_read_register (struct frame_info *frame, int regnum, void *buf)
{
gdb_assert (frame != NULL && frame->next != NULL);
frame_unwind_register (frame->next, regnum, buf);
}
void
frame_read_unsigned_register (struct frame_info *frame, int regnum,
ULONGEST *val)
{
/* NOTE: cagney/2002-10-31: There is a bit of dogma here - there is
always a frame. Both this, and the equivalent
frame_read_signed_register() function, can only be called with a
valid frame. If, for some reason, this function is called
without a frame then the problem isn't here, but rather in the
caller. It should of first created a frame and then passed that
in. */
/* NOTE: cagney/2002-10-31: As a side bar, keep in mind that the
``current_frame'' should not be treated as a special case. While
``get_next_frame (current_frame) == NULL'' currently holds, it
should, as far as possible, not be relied upon. In the future,
``get_next_frame (current_frame)'' may instead simply return a
normal frame object that simply always gets register values from
the register cache. Consequently, frame code should try to avoid
tests like ``if get_next_frame() == NULL'' and instead just rely
on recursive frame calls (like the below code) when manipulating
a frame chain. */
gdb_assert (frame != NULL && frame->next != NULL);
frame_unwind_unsigned_register (frame->next, regnum, val);
}
void
frame_read_signed_register (struct frame_info *frame, int regnum,
LONGEST *val)
{
/* See note above in frame_read_unsigned_register(). */
gdb_assert (frame != NULL && frame->next != NULL);
frame_unwind_signed_register (frame->next, regnum, val);
}
void
generic_unwind_get_saved_register (char *raw_buffer,
int *optimizedp,
CORE_ADDR *addrp,
struct frame_info *frame,
int regnum,
enum lval_type *lvalp)
{
int optimizedx;
CORE_ADDR addrx;
int realnumx;
enum lval_type lvalx;
if (!target_has_registers)
error ("No registers.");
/* Keep things simple, ensure that all the pointers (except valuep)
are non NULL. */
if (optimizedp == NULL)
optimizedp = &optimizedx;
if (lvalp == NULL)
lvalp = &lvalx;
if (addrp == NULL)
addrp = &addrx;
gdb_assert (frame != NULL && frame->next != NULL);
frame_register_unwind (frame->next, regnum, optimizedp, lvalp, addrp,
&realnumx, raw_buffer);
}
/* frame_register_read ()
Find and return the value of REGNUM for the specified stack frame.
The number of bytes copied is 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 (const char *name, int len)
{
int i;
if (len < 0)
len = strlen (name);
/* Search register name space. */
for (i = 0; i < NUM_REGS + NUM_PSEUDO_REGS; i++)
if (REGISTER_NAME (i) && len == strlen (REGISTER_NAME (i))
&& strncmp (name, REGISTER_NAME (i), len) == 0)
{
return i;
}
/* Try builtin registers. */
i = builtin_reg_map_name_to_regnum (name, len);
if (i >= 0)
{
/* A builtin register doesn't fall into the architecture's
register range. */
gdb_assert (i >= NUM_REGS + NUM_PSEUDO_REGS);
return i;
}
return -1;
}
const char *
frame_map_regnum_to_name (int regnum)
{
if (regnum < 0)
return NULL;
if (regnum < NUM_REGS + NUM_PSEUDO_REGS)
return REGISTER_NAME (regnum);
return builtin_reg_map_regnum_to_name (regnum);
}
/* Create a sentinel frame. */
struct frame_info *
create_sentinel_frame (struct regcache *regcache)
{
struct frame_info *frame = FRAME_OBSTACK_ZALLOC (struct frame_info);
frame->type = NORMAL_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;
/* Always unwind the PC as part of creating this frame. This
ensures that the frame's PC points at something valid. */
/* FIXME: cagney/2003-01-10: Problem here. Unwinding a sentinel
frame's PC may require information such as the frame's thread's
stop reason. Is it possible to get to that? */
frame->pc = frame_pc_unwind (frame);
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 *
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, eg, because it's 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;
}
/* Select frame FI (or NULL - to invalidate the current frame). */
void
select_frame (struct frame_info *fi)
{
register struct symtab *s;
deprecated_selected_frame = fi;
/* NOTE: cagney/2002-05-04: FI can be NULL. This occures when the
frame is being invalidated. */
if (selected_frame_level_changed_hook)
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 users 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)
{
s = find_pc_symtab (fi->pc);
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.
Unfortunatly, 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);
/* Only (older) architectures that implement the
DEPRECATED_FRAME_INIT_SAVED_REGS method should be using this
function. */
gdb_assert (DEPRECATED_FRAME_INIT_SAVED_REGS_P ());
/* Load the saved_regs register cache. */
if (get_frame_saved_regs (frame) == NULL)
DEPRECATED_FRAME_INIT_SAVED_REGS (frame);
if (get_frame_saved_regs (frame) != NULL
&& 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)
store_address (bufferp, REGISTER_RAW_SIZE (regnum),
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 = 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 (REGISTER_RAW_SIZE (regnum));
read_memory (get_frame_saved_regs (frame)[regnum], regs[regnum],
REGISTER_RAW_SIZE (regnum));
}
memcpy (bufferp, regs[regnum], REGISTER_RAW_SIZE (regnum));
#else
/* Read the value in from memory. */
read_memory (get_frame_saved_regs (frame)[regnum], bufferp,
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)
{
int fromleaf;
CORE_ADDR base;
CORE_ADDR pc;
if (frame_relative_level (next_frame) < 0)
{
/* FIXME: cagney/2003-03-14: We've got the extra special case of
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. */
(*id).base = read_fp ();
(*id).pc = read_pc ();
return;
}
/* Start out by assuming it's NULL. */
(*id) = null_frame_id;
if (frame_relative_level (next_frame) <= 0)
/* FIXME: 2002-11-09: Frameless functions can occure 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 = FRAMELESS_FUNCTION_INVOCATION (next_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 hande
it locally. */
base = get_frame_base (next_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. */
gdb_assert (DEPRECATED_FRAME_CHAIN_P ());
base = DEPRECATED_FRAME_CHAIN (next_frame);
if (!frame_chain_valid (base, next_frame))
return;
}
if (base == 0)
return;
/* FIXME: cagney/2002-06-08: This should probably return the frame's
function and not the PC (a.k.a. resume address). */
pc = frame_pc_unwind (next_frame);
id->pc = pc;
id->base = base;
}
const struct frame_unwind legacy_saved_regs_unwinder = {
legacy_saved_regs_this_id,
legacy_saved_regs_prev_register
};
const struct frame_unwind *legacy_saved_regs_unwind = &legacy_saved_regs_unwinder;
/* Function: deprecated_generic_get_saved_register
Find register number REGNUM relative to FRAME and put its (raw,
target format) contents in *RAW_BUFFER.
Set *OPTIMIZED if the variable was optimized out (and thus can't be
fetched). Note that this is never set to anything other than zero
in this implementation.
Set *LVAL to lval_memory, lval_register, or not_lval, depending on
whether the value was fetched from memory, from a register, or in a
strange and non-modifiable way (e.g. a frame pointer which was
calculated rather than fetched). We will use not_lval for values
fetched from generic dummy frames.
Set *ADDRP to the address, either in memory or as a REGISTER_BYTE
offset into the registers array. If the value is stored in a dummy
frame, set *ADDRP to zero.
The argument RAW_BUFFER must point to aligned memory. */
void
deprecated_generic_get_saved_register (char *raw_buffer, int *optimized,
CORE_ADDR *addrp,
struct frame_info *frame, int regnum,
enum lval_type *lval)
{
if (!target_has_registers)
error ("No registers.");
gdb_assert (DEPRECATED_FRAME_INIT_SAVED_REGS_P ());
/* Normal systems don't optimize out things with register numbers. */
if (optimized != NULL)
*optimized = 0;
if (addrp) /* default assumption: not found in memory */
*addrp = 0;
/* Note: since the current frame's registers could only have been
saved by frames INTERIOR TO the current frame, we skip examining
the current frame itself: otherwise, we would be getting the
previous frame's registers which were saved by the current frame. */
if (frame != NULL)
{
for (frame = get_next_frame (frame);
frame_relative_level (frame) >= 0;
frame = get_next_frame (frame))
{
if (get_frame_type (frame) == DUMMY_FRAME)
{
if (lval) /* found it in a CALL_DUMMY frame */
*lval = not_lval;
if (raw_buffer)
/* FIXME: cagney/2002-06-26: This should be via the
gdbarch_register_read() method so that it, on the
fly, constructs either a raw or pseudo register
from the raw register cache. */
regcache_raw_read
(generic_find_dummy_frame (get_frame_pc (frame),
get_frame_base (frame)),
regnum, raw_buffer);
return;
}
DEPRECATED_FRAME_INIT_SAVED_REGS (frame);
if (get_frame_saved_regs (frame) != NULL
&& get_frame_saved_regs (frame)[regnum] != 0)
{
if (lval) /* found it saved on the stack */
*lval = lval_memory;
if (regnum == SP_REGNUM)
{
if (raw_buffer) /* SP register treated specially */
store_address (raw_buffer, REGISTER_RAW_SIZE (regnum),
get_frame_saved_regs (frame)[regnum]);
}
else
{
if (addrp) /* any other register */
*addrp = get_frame_saved_regs (frame)[regnum];
if (raw_buffer)
read_memory (get_frame_saved_regs (frame)[regnum], raw_buffer,
REGISTER_RAW_SIZE (regnum));
}
return;
}
}
}
/* If we get thru the loop to this point, it means the register was
not saved in any frame. Return the actual live-register value. */
if (lval) /* found it in a live register */
*lval = lval_register;
if (addrp)
*addrp = REGISTER_BYTE (regnum);
if (raw_buffer)
deprecated_read_register_gen (regnum, raw_buffer);
}
/* Determine the frame's type based on its PC. */
static enum frame_type
frame_type_from_pc (CORE_ADDR pc)
{
/* FIXME: cagney/2002-11-24: Can't yet directly call
pc_in_dummy_frame() as some architectures don't set
PC_IN_CALL_DUMMY() to generic_pc_in_call_dummy() (remember the
latter is implemented by simply calling pc_in_dummy_frame). */
if (DEPRECATED_USE_GENERIC_DUMMY_FRAMES
&& DEPRECATED_PC_IN_CALL_DUMMY (pc, 0, 0))
return DUMMY_FRAME;
else
{
char *name;
find_pc_partial_function (pc, &name, NULL, NULL);
if (PC_IN_SIGTRAMP (pc, name))
return SIGTRAMP_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;
fi = frame_obstack_zalloc (sizeof (struct frame_info));
fi->frame = addr;
fi->pc = pc;
fi->next = create_sentinel_frame (current_regcache);
fi->type = frame_type_from_pc (pc);
if (DEPRECATED_INIT_EXTRA_FRAME_INFO_P ())
DEPRECATED_INIT_EXTRA_FRAME_INFO (0, fi);
/* Select/initialize an unwind function. */
fi->unwind = frame_unwind_find_by_pc (current_gdbarch, fi->pc);
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;
}
/* 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 ();
}
/* 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, INIT_FRAME_PC and INIT_FRAME_PC_FIRST. */
static struct frame_info *
legacy_get_prev_frame (struct frame_info *this_frame)
{
CORE_ADDR address = 0;
struct frame_info *prev;
int fromleaf;
/* 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, in get_prev_frame will stop repeated
memory allocation calls. */
prev = FRAME_OBSTACK_ZALLOC (struct frame_info);
prev->level = this_frame->level + 1;
/* 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,
DEPRECATED_INIT_FRAME_PC_FIRST and
DEPRECATED_FRAME_INIT_SAVED_REGS methods are full of work-arounds
that handle the frame not being correctly set from the start.
Unfortunatly those same work-arounds rely on the type defaulting
to NORMAL_FRAME. Ulgh! The new frame code does not have this
problem. */
prev->type = NORMAL_FRAME;
/* 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. */
prev->pc = frame_pc_unwind (this_frame);
if (prev->pc == 0)
{
/* The allocated PREV_FRAME will be reclaimed when the frame
obstack is next purged. */
if (frame_debug)
fprintf_unfiltered (gdb_stdlog,
"Outermost frame - unwound PC zero\n");
return NULL;
}
prev->type = frame_type_from_pc (prev->pc);
/* Set the unwind functions based on that identified PC. */
prev->unwind = frame_unwind_find_by_pc (current_gdbarch, prev->pc);
/* 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. */
/* Assume hand_function_call(), via SAVE_DUMMY_FRAME_TOS,
previously saved the dummy frame's ID. Things only work
if the two return the same value. */
gdb_assert (SAVE_DUMMY_FRAME_TOS_P ());
/* 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->id = 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->id.base = read_fp ();
prev->id.pc = read_pc ();
}
/* Check that the unwound ID is valid. */
if (!frame_id_p (prev->id))
{
if (frame_debug)
fprintf_unfiltered (gdb_stdlog,
"Outermost legacy sentinel frame - unwound frame 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. */
/* FIXME: cagney/2002-12-18: Instead of this hack, should only
store the frame ID in PREV_FRAME. Unfortunatly, some
architectures (HP/UX) still reply on EXTRA_FRAME_INFO and,
hence, still poke at the "struct frame_info" object directly. */
prev->frame = prev->id.base;
/* Link it in. */
this_frame->prev = prev;
prev->next = this_frame;
/* 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. Unfortunatly 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);
}
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 occure 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 = 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 hande
it locally. */
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. */
gdb_assert (DEPRECATED_FRAME_CHAIN_P ());
address = DEPRECATED_FRAME_CHAIN (this_frame);
if (!frame_chain_valid (address, this_frame))
return 0;
}
if (address == 0)
return 0;
/* Link in the already allocated prev frame. */
this_frame->prev = prev;
prev->next = this_frame;
prev->frame = 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.
We shouldn't need DEPRECATED_INIT_FRAME_PC_FIRST to add more
complication to an already overcomplicated part of GDB.
gnu@cygnus.com, 15Sep92.
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
(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 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 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 superseed by
frame_pc_unwind() and that function does have somewhere to cache
that PC value. */
if (DEPRECATED_INIT_FRAME_PC_FIRST_P ())
prev->pc = (DEPRECATED_INIT_FRAME_PC_FIRST (fromleaf, prev));
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 ())
prev->pc = 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 (prev->frame == this_frame->frame
&& prev->pc == this_frame->pc)
{
this_frame->prev = NULL;
obstack_free (&frame_cache_obstack, prev);
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. */
prev->unwind = frame_unwind_find_by_pc (current_gdbarch, prev->pc);
/* NOTE: cagney/2002-11-18: The code segments, found in
create_new_frame and get_prev_frame(), that initializes the
frames 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_USE_GENERIC_DUMMY_FRAMES
&& (DEPRECATED_PC_IN_CALL_DUMMY_P ()
? DEPRECATED_PC_IN_CALL_DUMMY (prev->pc, 0, 0)
: pc_in_dummy_frame (prev->pc)))
prev->type = DUMMY_FRAME;
else
{
/* FIXME: cagney/2002-11-10: This should be moved to before the
INIT code above so that the INIT code knows what the frame's
type is (in fact, for a [generic] dummy-frame, the type can
be set and then the entire initialization can be skipped.
Unforunatly, its the INIT code that sets the PC (Hmm, catch
22). */
char *name;
find_pc_partial_function (prev->pc, &name, NULL, NULL);
if (PC_IN_SIGTRAMP (prev->pc, name))
prev->type = SIGTRAMP_FRAME;
/* FIXME: cagney/2002-11-11: Leave prev->type alone. Some
architectures are forcing the frame's type in INIT so we
don't want to override it here. Remember, NORMAL_FRAME == 0,
so it all works (just :-/). Once this initialization is
moved to the start of this function, all this nastness will
go away. */
}
return prev;
}
/* Return a structure containing various interesting information
about the frame that called THIS_FRAME. Returns NULL
if there is no such frame. */
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 is
block_innermost_frame() is, when the target has no state
(registers, memory, ...), 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. */
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);
if (this_frame->level >= 0
&& !backtrace_below_main
&& inside_main_func (get_frame_pc (this_frame)))
/* Don't unwind past main(), bug 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. */
{
if (frame_debug)
fprintf_unfiltered (gdb_stdlog,
"Outermost frame - inside main func.\n");
return NULL;
}
/* Only try to do the unwind once. */
if (this_frame->prev_p)
return this_frame->prev;
this_frame->prev_p = 1;
/* If we're inside the entry file, it isn't valid. Don't apply this
test to a dummy frame - dummy frame PC's typically land in the
entry file. Don't apply this test to the sentinel frame.
Sentinel frames should always be allowed to unwind. */
/* NOTE: drow/2002-12-25: should there be a way to disable this
check? It assumes a single small entry file, and the way some
debug readers (e.g. dbxread) figure out which object is the
entry file is somewhat hokey. */
/* NOTE: cagney/2003-01-10: If there is a way of disabling this test
then it should probably be moved to before the ->prev_p test,
above. */
if (this_frame->type != DUMMY_FRAME && this_frame->level >= 0
&& inside_entry_file (get_frame_pc (this_frame)))
{
if (frame_debug)
fprintf_unfiltered (gdb_stdlog,
"Outermost frame - inside entry file\n");
return NULL;
}
/* 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 PC's 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. */
if (0
&& this_frame->type != DUMMY_FRAME && this_frame->level >= 0
&& inside_entry_func (get_frame_pc (this_frame)))
{
if (frame_debug)
fprintf_unfiltered (gdb_stdlog,
"Outermost frame - inside entry func\n");
return NULL;
}
/* 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);
if (frame_debug && prev_frame == NULL)
fprintf_unfiltered (gdb_stdlog,
"Outermost frame - legacy_get_prev_frame NULL.\n");
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. */
if (this_frame->level >= 0 && !frame_id_p (get_frame_id (this_frame)))
{
if (frame_debug)
fprintf_filtered (gdb_stdlog,
"Outermost frame - 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 frame unwind goes backwards.
Since the sentinel frame isn't valid, don't apply this if this
frame is entier the inner-most or sentinel frame. */
if (this_frame->level > 0
&& frame_id_inner (get_frame_id (this_frame),
get_frame_id (this_frame->next)))
error ("This frame inner-to next frame (corrupt stack?)");
/* Check that this and the next frame are different. If they are
not, there is most likely a stack cycle. As with the inner-than
test, avoid the inner-most and sentinel frames. */
/* FIXME: cagney/2003-03-17: Can't yet enable this this check. The
frame_id_eq() method doesn't yet use function addresses when
comparing frame IDs. */
if (0
&& this_frame->level > 0
&& frame_id_eq (get_frame_id (this_frame),
get_frame_id (this_frame->next)))
error ("This frame identical to next 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;
/* 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, 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. */
prev_frame->pc = frame_pc_unwind (this_frame);
if (prev_frame->pc == 0)
{
/* The allocated PREV_FRAME will be reclaimed when the frame
obstack is next purged. */
if (frame_debug)
fprintf_unfiltered (gdb_stdlog,
"Outermost frame - unwound PC zero\n");
return NULL;
}
prev_frame->type = frame_type_from_pc (prev_frame->pc);
/* Set the unwind functions based on that identified PC. */
prev_frame->unwind = frame_unwind_find_by_pc (current_gdbarch,
prev_frame->pc);
/* Find the prev's frame's ID. */
/* The callee expects to be invoked with:
this->unwind->this_id (this->next, &this->cache, &this->id);
The below is carefully shifted one frame `to the left' so that
both the unwind->this_id and unwind->prev_register methods are
consistently invoked with NEXT_FRAME and THIS_PROLOGUE_CACHE.
Also note that, while the PC for this new previous frame was
unwound first (see above), the below is the first call that
[potentially] requires analysis of the new previous frame's
prologue. Consequently, it is this call, that typically ends up
initializing the previous frame's prologue cache. */
prev_frame->unwind->this_id (this_frame,
&prev_frame->prologue_cache,
&prev_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.
The very old VAX frame_args_address_correct() method 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. */
/* FIXME: cagney/2002-12-18: Instead of this hack, should only store
the frame ID in PREV_FRAME. Unfortunatly, some architectures
(HP/UX) still reply on EXTRA_FRAME_INFO and, hence, still poke at
the "struct frame_info" object directly. */
prev_frame->frame = prev_frame->id.base;
/* Link it in. */
this_frame->prev = prev_frame;
prev_frame->next = this_frame;
return prev_frame;
}
CORE_ADDR
get_frame_pc (struct frame_info *frame)
{
return frame->pc;
}
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 (frame->pc, 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 fi->frame;
}
/* 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 targets still don't use [generic] dummy frames. Catch them
here. */
if (!DEPRECATED_USE_GENERIC_DUMMY_FRAMES
&& deprecated_frame_in_dummy (frame))
return DUMMY_FRAME;
return frame->type;
}
void
deprecated_set_frame_type (struct frame_info *frame, enum frame_type type)
{
/* Arrrg! See comment in "frame.h". */
frame->type = type;
}
#ifdef FRAME_FIND_SAVED_REGS
/* XXX - deprecated. This is a compatibility function for targets
that do not yet implement DEPRECATED_FRAME_INIT_SAVED_REGS. */
/* Find the addresses in which registers are saved in FRAME. */
void
deprecated_get_frame_saved_regs (struct frame_info *frame,
struct frame_saved_regs *saved_regs_addr)
{
if (frame->saved_regs == NULL)
{
frame->saved_regs = (CORE_ADDR *)
frame_obstack_zalloc (SIZEOF_FRAME_SAVED_REGS);
}
if (saved_regs_addr == NULL)
{
struct frame_saved_regs saved_regs;
FRAME_FIND_SAVED_REGS (frame, saved_regs);
memcpy (frame->saved_regs, &saved_regs, SIZEOF_FRAME_SAVED_REGS);
}
else
{
FRAME_FIND_SAVED_REGS (frame, *saved_regs_addr);
memcpy (frame->saved_regs, saved_regs_addr, SIZEOF_FRAME_SAVED_REGS);
}
}
#endif
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)
{
/* See comment in "frame.h". */
frame->pc = pc;
/* NOTE: cagney/2003-03-11: Some architectures (e.g., Arm) are
maintaining a locally allocated frame object. Since such frame's
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->pc_unwind_cache = pc;
frame->next->pc_unwind_cache_p = 1;
}
}
void
deprecated_update_frame_base_hack (struct frame_info *frame, CORE_ADDR base)
{
/* See comment in "frame.h". */
frame->frame = base;
}
void
deprecated_set_frame_saved_regs_hack (struct frame_info *frame,
CORE_ADDR *saved_regs)
{
frame->saved_regs = saved_regs;
}
void
deprecated_set_frame_extra_info_hack (struct frame_info *frame,
struct frame_extra_info *extra_info)
{
frame->extra_info = extra_info;
}
void
deprecated_set_frame_next_hack (struct frame_info *fi,
struct frame_info *next)
{
fi->next = next;
}
void
deprecated_set_frame_prev_hack (struct frame_info *fi,
struct frame_info *prev)
{
fi->prev = prev;
}
struct context *
deprecated_get_frame_context (struct frame_info *fi)
{
return fi->context;
}
void
deprecated_set_frame_context (struct frame_info *fi,
struct context *context)
{
fi->context = context;
}
struct frame_info *
deprecated_frame_xmalloc (void)
{
struct frame_info *frame = XMALLOC (struct frame_info);
memset (frame, 0, sizeof (struct frame_info));
return frame;
}
struct frame_info *
deprecated_frame_xmalloc_with_cleanup (long sizeof_saved_regs,
long sizeof_extra_info)
{
struct frame_info *frame = deprecated_frame_xmalloc ();
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;
}
int
legacy_frame_p (struct gdbarch *current_gdbarch)
{
return (DEPRECATED_INIT_FRAME_PC_P ()
|| DEPRECATED_INIT_FRAME_PC_FIRST_P ()
|| DEPRECATED_INIT_EXTRA_FRAME_INFO_P ()
|| DEPRECATED_FRAME_CHAIN_P ()
|| !gdbarch_unwind_dummy_id_p (current_gdbarch)
|| !SAVE_DUMMY_FRAME_TOS_P ());
}
void
_initialize_frame (void)
{
obstack_init (&frame_cache_obstack);
/* FIXME: cagney/2003-01-19: This command needs a rename. Suggest
`set backtrace {past,beyond,...}-main'. Also suggest adding `set
backtrace ...-start' to control backtraces past start. The
problem with `below' is that it stops the `up' command. */
add_setshow_boolean_cmd ("backtrace-below-main", class_obscure,
&backtrace_below_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, &setlist, &showlist);
/* 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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