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95adb866d7
darling-gdb/gdb/frame.c
Andrew Cagney 95adb866d7 2002-11-09 Andrew Cagney <ac131313@redhat.com> 
* frame.c (get_prev_frame): Cleanups.  Eliminate redundant tests
	for a NULL NEXT_FRAME.  Simplify fromleaf initialization.  Add
	more comments.  Zap dead code.
2002-11-09 17:45:17 +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 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 "gdbcore.h"
#include "annotate.h"
/* Return a frame uniq ID that can be used to, later re-find the
frame. */
void
get_frame_id (struct frame_info *fi, struct frame_id *id)
{
if (fi == NULL)
{
id->base = 0;
id->pc = 0;
}
else
{
id->base = FRAME_FP (fi);
id->pc = fi->pc;
}
}
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 (id.base == 0 && id.pc == 0)
return NULL;
for (frame = get_current_frame ();
frame != NULL;
frame = get_prev_frame (frame))
{
if (INNER_THAN (FRAME_FP (frame), id.base))
/* ``inner/current < frame < id.base''. Keep looking along
the frame chain. */
continue;
if (INNER_THAN (id.base, FRAME_FP (frame)))
/* ``inner/current < id.base < frame''. Oops, gone past it.
Just give up. */
return NULL;
/* FIXME: cagney/2002-04-21: This isn't sufficient. It should
use id.pc to check that the two frames belong to the same
function. Otherwise we'll do things like match dummy frames
or mis-match frameless functions. However, until someone
notices, stick with the existing behavour. */
return frame;
}
return NULL;
}
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/2002-04-14: It would be nice if, instead of a
special case, there was always an inner frame dedicated to the
hardware registers. Unfortunatly, there is too much unwind code
around that looks up/down the frame chain while making the
assumption that each frame level is using the same unwind code. */
if (frame == NULL)
{
/* We're in the inner-most frame, get the value direct from the
register cache. */
*optimizedp = 0;
*lvalp = lval_register;
/* ULGH! Code uses the offset into the raw register byte array
as a way of identifying a register. */
*addrp = REGISTER_BYTE (regnum);
/* Should this code test ``register_cached (regnum) < 0'' and do
something like set realnum to -1 when the register isn't
available? */
*realnump = regnum;
if (bufferp)
deprecated_read_register_gen (regnum, bufferp);
return;
}
/* Ask this frame to unwind its register. */
frame->register_unwind (frame, &frame->register_unwind_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 (GET_SAVED_REGISTER_P ())
{
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;
}
/* Reached the the bottom (youngest, inner most) of the frame chain
(youngest, inner most) frame, go direct to the hardware register
cache (do not pass go, do not try to cache the value, ...). The
unwound value would have been cached in frame->next but that
doesn't exist. This doesn't matter as the hardware register
cache is stopping any unnecessary accesses to the target. */
/* NOTE: cagney/2002-04-14: It would be nice if, instead of a
special case, there was always an inner frame dedicated to the
hardware registers. Unfortunatly, there is too much unwind code
around that looks up/down the frame chain while making the
assumption that each frame level is using the same unwind code. */
if (frame == NULL)
frame_register_unwind (NULL, regnum, optimizedp, lvalp, addrp, realnump,
bufferp);
else
frame_register_unwind (frame->next, regnum, optimizedp, lvalp, addrp,
realnump, bufferp);
}
void
frame_unwind_signed_register (struct frame_info *frame, int regnum,
LONGEST *val)
{
int optimized;
CORE_ADDR addr;
int realnum;
enum lval_type lval;
void *buf = alloca (MAX_REGISTER_RAW_SIZE);
frame_register_unwind (frame, regnum, &optimized, &lval, &addr,
&realnum, buf);
(*val) = extract_signed_integer (buf, REGISTER_VIRTUAL_SIZE (regnum));
}
void
frame_unwind_unsigned_register (struct frame_info *frame, int regnum,
ULONGEST *val)
{
int optimized;
CORE_ADDR addr;
int realnum;
enum lval_type lval;
void *buf = alloca (MAX_REGISTER_RAW_SIZE);
frame_register_unwind (frame, regnum, &optimized, &lval, &addr,
&realnum, buf);
(*val) = extract_unsigned_integer (buf, REGISTER_VIRTUAL_SIZE (regnum));
}
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_unwind_unsigned_register (get_next_frame (frame), regnum, val);
}
void
frame_read_signed_register (struct frame_info *frame, int regnum,
LONGEST *val)
{
/* See note in frame_read_unsigned_register(). */
gdb_assert (frame != NULL);
frame_unwind_signed_register (get_next_frame (frame), 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;
/* Reached the the bottom (youngest, inner most) of the frame chain
(youngest, inner most) frame, go direct to the hardware register
cache (do not pass go, do not try to cache the value, ...). The
unwound value would have been cached in frame->next but that
doesn't exist. This doesn't matter as the hardware register
cache is stopping any unnecessary accesses to the target. */
/* NOTE: cagney/2002-04-14: It would be nice if, instead of a
special case, there was always an inner frame dedicated to the
hardware registers. Unfortunatly, there is too much unwind code
around that looks up/down the frame chain while making the
assumption that each frame level is using the same unwind code. */
if (frame == NULL)
frame_register_unwind (NULL, regnum, optimizedp, lvalp, addrp, &realnumx,
raw_buffer);
else
frame_register_unwind (frame->next, regnum, optimizedp, lvalp, addrp,
&realnumx, raw_buffer);
}
void
get_saved_register (char *raw_buffer,
int *optimized,
CORE_ADDR *addrp,
struct frame_info *frame,
int regnum,
enum lval_type *lval)
{
if (GET_SAVED_REGISTER_P ())
{
GET_SAVED_REGISTER (raw_buffer, optimized, addrp, frame, regnum, lval);
return;
}
generic_unwind_get_saved_register (raw_buffer, optimized, addrp, frame,
regnum, lval);
}
/* 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;
/* 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);
}
/* 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_alloc (unsigned long size)
{
return obstack_alloc (&frame_cache_obstack, size);
}
void
frame_saved_regs_zalloc (struct frame_info *fi)
{
fi->saved_regs = (CORE_ADDR *)
frame_obstack_alloc (SIZEOF_FRAME_SAVED_REGS);
memset (fi->saved_regs, 0, SIZEOF_FRAME_SAVED_REGS);
}
/* Return the innermost (currently executing) stack frame. */
struct frame_info *
get_current_frame (void)
{
if (current_frame == NULL)
{
if (target_has_stack)
current_frame = create_new_frame (read_fp (), read_pc ());
else
error ("No stack.");
}
return current_frame;
}
void
set_current_frame (struct frame_info *frame)
{
current_frame = frame;
}
/* 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
frame_saved_regs_register_unwind (struct frame_info *frame, void **cache,
int regnum, int *optimizedp,
enum lval_type *lvalp, CORE_ADDR *addrp,
int *realnump, void *bufferp)
{
/* There is always a frame at this point. And THIS is the frame
we're interested in. */
gdb_assert (frame != NULL);
/* If we're using generic dummy frames, we'd better not be in a call
dummy. (generic_call_dummy_register_unwind ought to have been called
instead.) */
gdb_assert (!(USE_GENERIC_DUMMY_FRAMES
&& PC_IN_CALL_DUMMY (frame->pc, frame->frame, frame->frame)));
/* Load the saved_regs register cache. */
if (frame->saved_regs == NULL)
FRAME_INIT_SAVED_REGS (frame);
if (frame->saved_regs != NULL
&& frame->saved_regs[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),
frame->saved_regs[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 = frame->saved_regs[regnum];
*realnump = -1;
if (bufferp != NULL)
{
#if 1
/* Save each register value, as it is read in, in a
frame based cache. */
void **regs = (*cache);
if (regs == NULL)
{
int sizeof_cache = ((NUM_REGS + NUM_PSEUDO_REGS)
* sizeof (void *));
regs = frame_obstack_alloc (sizeof_cache);
memset (regs, 0, sizeof_cache);
(*cache) = regs;
}
if (regs[regnum] == NULL)
{
regs[regnum]
= frame_obstack_alloc (REGISTER_RAW_SIZE (regnum));
read_memory (frame->saved_regs[regnum], regs[regnum],
REGISTER_RAW_SIZE (regnum));
}
memcpy (bufferp, regs[regnum], REGISTER_RAW_SIZE (regnum));
#else
/* Read the value in from memory. */
read_memory (frame->saved_regs[regnum], bufferp,
REGISTER_RAW_SIZE (regnum));
#endif
}
}
return;
}
/* No luck, assume this and the next frame have the same register
value. If a value is needed, pass the request on down the chain;
otherwise just return an indication that the value is in the same
register as the next frame. */
if (bufferp == NULL)
{
*optimizedp = 0;
*lvalp = lval_register;
*addrp = 0;
*realnump = regnum;
}
else
{
frame_register_unwind (frame->next, regnum, optimizedp, lvalp, addrp,
realnump, bufferp);
}
}
/* Function: 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.
To use this implementation, define a function called
"get_saved_register" in your target code, which simply passes all
of its arguments to this function.
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.");
/* 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. */
while (frame && ((frame = frame->next) != NULL))
{
if (PC_IN_CALL_DUMMY (frame->pc, frame->frame, frame->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 (frame->pc,
frame->frame),
regnum, raw_buffer);
return;
}
FRAME_INIT_SAVED_REGS (frame);
if (frame->saved_regs != NULL
&& frame->saved_regs[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),
frame->saved_regs[regnum]);
}
else
{
if (addrp) /* any other register */
*addrp = frame->saved_regs[regnum];
if (raw_buffer)
read_memory (frame->saved_regs[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);
}
/* Using the PC, select a mechanism for unwinding a frame returning
the previous frame. The register unwind function should, on
demand, initialize the ->context object. */
static void
set_unwind_by_pc (CORE_ADDR pc, CORE_ADDR fp,
frame_register_unwind_ftype **unwind)
{
if (!USE_GENERIC_DUMMY_FRAMES)
/* Still need to set this to something. The ``info frame'' code
calls this function to find out where the saved registers are.
Hopefully this is robust enough to stop any core dumps and
return vaguely correct values.. */
*unwind = frame_saved_regs_register_unwind;
else if (PC_IN_CALL_DUMMY (pc, fp, fp))
*unwind = dummy_frame_register_unwind;
else
*unwind = frame_saved_regs_register_unwind;
}
/* 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;
char *name;
fi = (struct frame_info *)
obstack_alloc (&frame_cache_obstack,
sizeof (struct frame_info));
/* Zero all fields by default. */
memset (fi, 0, sizeof (struct frame_info));
fi->frame = addr;
fi->pc = pc;
find_pc_partial_function (pc, &name, (CORE_ADDR *) NULL, (CORE_ADDR *) NULL);
fi->signal_handler_caller = PC_IN_SIGTRAMP (fi->pc, name);
if (INIT_EXTRA_FRAME_INFO_P ())
INIT_EXTRA_FRAME_INFO (0, fi);
/* Select/initialize an unwind function. */
set_unwind_by_pc (fi->pc, fi->frame, &fi->register_unwind);
return fi;
}
/* Return the frame that FRAME calls (NULL if FRAME is the innermost
frame). */
struct frame_info *
get_next_frame (struct frame_info *frame)
{
return frame->next;
}
/* 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 ());
}
}
/* Return a structure containing various interesting information
about the frame that called NEXT_FRAME. Returns NULL
if there is no such frame. */
struct frame_info *
get_prev_frame (struct frame_info *next_frame)
{
CORE_ADDR address = 0;
struct frame_info *prev;
int fromleaf;
char *name;
/* 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. */
if (next_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
NEXT_FRAME. */
return current_frame;
}
/* If we have the prev one, return it. */
if (next_frame->prev)
/* FIXME: cagney/2002-11-09: Rather than relying on ->PREV being
non-NULL, there should be a predicate (->prev_p?). That would
stop this function constantly trying to chain beyond the
outermost frame. */
return next_frame->prev;
/* 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 NEXT_FRAME is a frameless
function invocation. */
if (next_frame->next == NULL)
/* 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. */
address = FRAME_FP (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. */
address = FRAME_CHAIN (next_frame);
/* FIXME: cagney/2002-06-08: There should be two tests here.
The first would check for a valid frame chain based on a user
selectable policy. The default being ``stop at main'' (as
implemented by generic_func_frame_chain_valid()). Other
policies would be available - stop at NULL, .... The second
test, if provided by the target architecture, would check for
more exotic cases - most target architectures wouldn't bother
with this second case. */
if (!FRAME_CHAIN_VALID (address, next_frame))
return 0;
}
if (address == 0)
return 0;
/* Create an initially zero previous frame. */
prev = (struct frame_info *)
obstack_alloc (&frame_cache_obstack,
sizeof (struct frame_info));
memset (prev, 0, sizeof (struct frame_info));
/* Link it in. */
next_frame->prev = prev;
prev->next = next_frame;
prev->frame = address;
prev->level = next_frame->level + 1;
/* This change should not be needed, FIXME! We should determine
whether any targets *need* INIT_FRAME_PC to happen after
INIT_EXTRA_FRAME_INFO and come up with a simple way to express
what goes on here.
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).
INIT_FRAME_PC is only called from here, always after
INIT_EXTRA_FRAME_INFO.
The catch is the MIPS, where INIT_EXTRA_FRAME_INFO requires the
PC value (which hasn't been set yet). Some other machines appear
to require INIT_EXTRA_FRAME_INFO before they can do
INIT_FRAME_PC. Phoo.
We shouldn't need INIT_FRAME_PC_FIRST to add more complication to
an already overcomplicated part of GDB. gnu@cygnus.com, 15Sep92.
Assuming that some machines need INIT_FRAME_PC after
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 INIT_EXTRA_FRAME_INFO and
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
FRAME_CHAIN_VALID called *before* INIT_EXTRA_FRAME_INFO (there is
no good way to get information deduced in 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 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 (NEXT_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 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. */
INIT_FRAME_PC_FIRST (fromleaf, prev);
if (INIT_EXTRA_FRAME_INFO_P ())
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. */
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 FRAME_CHAIN or thereabouts, but it seems like there
is no reason this can't be an architecture-independent check. */
if (prev->frame == next_frame->frame
&& prev->pc == next_frame->pc)
{
next_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. */
set_unwind_by_pc (prev->pc, prev->frame, &prev->register_unwind);
find_pc_partial_function (prev->pc, &name,
(CORE_ADDR *) NULL, (CORE_ADDR *) NULL);
if (PC_IN_SIGTRAMP (prev->pc, name))
prev->signal_handler_caller = 1;
return prev;
}
CORE_ADDR
get_frame_pc (struct frame_info *frame)
{
return frame->pc;
}
#ifdef FRAME_FIND_SAVED_REGS
/* XXX - deprecated. This is a compatibility function for targets
that do not yet implement FRAME_INIT_SAVED_REGS. */
/* Find the addresses in which registers are saved in FRAME. */
void
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_alloc (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
void
_initialize_frame (void)
{
obstack_init (&frame_cache_obstack);
}
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