mirror of
https://sourceware.org/git/binutils-gdb.git
synced 2024-12-27 04:52:05 +08:00
8480a37e14
We currently pass frames to function by value, as `frame_info_ptr`.
This is somewhat expensive:
- the size of `frame_info_ptr` is 64 bytes, which is a bit big to pass
by value
- the constructors and destructor link/unlink the object in the global
`frame_info_ptr::frame_list` list. This is an `intrusive_list`, so
it's not so bad: it's just assigning a few points, there's no memory
allocation as if it was `std::list`, but still it's useless to do
that over and over.
As suggested by Tom Tromey, change many function signatures to accept
`const frame_info_ptr &` instead of `frame_info_ptr`.
Some functions reassign their `frame_info_ptr` parameter, like:
void
the_func (frame_info_ptr frame)
{
for (; frame != nullptr; frame = get_prev_frame (frame))
{
...
}
}
I wondered what to do about them, do I leave them as-is or change them
(and need to introduce a separate local variable that can be
re-assigned). I opted for the later for consistency. It might not be
clear why some functions take `const frame_info_ptr &` while others take
`frame_info_ptr`. Also, if a function took a `frame_info_ptr` because
it did re-assign its parameter, I doubt that we would think to change it
to `const frame_info_ptr &` should the implementation change such that
it doesn't need to take `frame_info_ptr` anymore. It seems better to
have a simple rule and apply it everywhere.
Change-Id: I59d10addef687d157f82ccf4d54f5dde9a963fd0
Approved-By: Andrew Burgess <aburgess@redhat.com>
239 lines
9.2 KiB
C++
239 lines
9.2 KiB
C++
/* Definitions for a frame unwinder, for GDB, the GNU debugger.
|
|
|
|
Copyright (C) 2003-2024 Free Software Foundation, Inc.
|
|
|
|
This file is part of GDB.
|
|
|
|
This program is free software; you can redistribute it and/or modify
|
|
it under the terms of the GNU General Public License as published by
|
|
the Free Software Foundation; either version 3 of the License, or
|
|
(at your option) any later version.
|
|
|
|
This program is distributed in the hope that it will be useful,
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
GNU General Public License for more details.
|
|
|
|
You should have received a copy of the GNU General Public License
|
|
along with this program. If not, see <http://www.gnu.org/licenses/>. */
|
|
|
|
#if !defined (FRAME_UNWIND_H)
|
|
#define FRAME_UNWIND_H 1
|
|
|
|
struct frame_data;
|
|
class frame_info_ptr;
|
|
struct frame_id;
|
|
struct frame_unwind;
|
|
struct gdbarch;
|
|
struct regcache;
|
|
struct value;
|
|
|
|
#include "frame.h"
|
|
|
|
/* The following unwind functions assume a chain of frames forming the
|
|
sequence: (outer) prev <-> this <-> next (inner). All the
|
|
functions are called with this frame's `struct frame_info' and
|
|
prologue cache.
|
|
|
|
THIS frame's register values can be obtained by unwinding NEXT
|
|
frame's registers (a recursive operation).
|
|
|
|
THIS frame's prologue cache can be used to cache information such
|
|
as where this frame's prologue stores the previous frame's
|
|
registers. */
|
|
|
|
/* Given THIS frame, take a whiff of its registers (namely
|
|
the PC and attributes) and if SELF is the applicable unwinder,
|
|
return non-zero. Possibly also initialize THIS_PROLOGUE_CACHE; but
|
|
only if returning 1. Initializing THIS_PROLOGUE_CACHE in other
|
|
cases (0 return) is invalid. In case of exception, the caller has
|
|
to set *THIS_PROLOGUE_CACHE to NULL. */
|
|
|
|
typedef int (frame_sniffer_ftype) (const struct frame_unwind *self,
|
|
const frame_info_ptr &this_frame,
|
|
void **this_prologue_cache);
|
|
|
|
typedef unwind_stop_reason (frame_unwind_stop_reason_ftype)
|
|
(const frame_info_ptr &this_frame, void **this_prologue_cache);
|
|
|
|
/* A default frame sniffer which always accepts the frame. Used by
|
|
fallback prologue unwinders. */
|
|
|
|
int default_frame_sniffer (const struct frame_unwind *self,
|
|
const frame_info_ptr &this_frame,
|
|
void **this_prologue_cache);
|
|
|
|
/* A default stop_reason callback which always claims the frame is
|
|
unwindable. */
|
|
|
|
enum unwind_stop_reason
|
|
default_frame_unwind_stop_reason (const frame_info_ptr &this_frame,
|
|
void **this_cache);
|
|
|
|
/* A default unwind_pc callback that simply unwinds the register identified
|
|
by GDBARCH_PC_REGNUM. */
|
|
|
|
extern CORE_ADDR default_unwind_pc (struct gdbarch *gdbarch,
|
|
const frame_info_ptr &next_frame);
|
|
|
|
/* A default unwind_sp callback that simply unwinds the register identified
|
|
by GDBARCH_SP_REGNUM. */
|
|
|
|
extern CORE_ADDR default_unwind_sp (struct gdbarch *gdbarch,
|
|
const frame_info_ptr &next_frame);
|
|
|
|
/* Assuming the frame chain: (outer) prev <-> this <-> next (inner);
|
|
use THIS frame, and through it the NEXT frame's register unwind
|
|
method, to determine the frame ID of THIS frame.
|
|
|
|
A frame ID provides an invariant that can be used to re-identify an
|
|
instance of a frame. It is a combination of the frame's `base' and
|
|
the frame's function's code address.
|
|
|
|
Traditionally, THIS frame's ID was determined by examining THIS
|
|
frame's function's prologue, and identifying the register/offset
|
|
used as THIS frame's base.
|
|
|
|
Example: An examination of THIS frame's prologue reveals that, on
|
|
entry, it saves the PC(+12), SP(+8), and R1(+4) registers
|
|
(decrementing the SP by 12). Consequently, the frame ID's base can
|
|
be determined by adding 12 to the THIS frame's stack-pointer, and
|
|
the value of THIS frame's SP can be obtained by unwinding the NEXT
|
|
frame's SP.
|
|
|
|
THIS_PROLOGUE_CACHE can be used to share any prolog analysis data
|
|
with the other unwind methods. Memory for that cache should be
|
|
allocated using FRAME_OBSTACK_ZALLOC(). */
|
|
|
|
typedef void (frame_this_id_ftype) (const frame_info_ptr &this_frame,
|
|
void **this_prologue_cache,
|
|
struct frame_id *this_id);
|
|
|
|
/* Assuming the frame chain: (outer) prev <-> this <-> next (inner);
|
|
use THIS frame, and implicitly the NEXT frame's register unwind
|
|
method, to unwind THIS frame's registers (returning the value of
|
|
the specified register REGNUM in the previous frame).
|
|
|
|
Traditionally, THIS frame's registers were unwound by examining
|
|
THIS frame's function's prologue and identifying which registers
|
|
that prolog code saved on the stack.
|
|
|
|
Example: An examination of THIS frame's prologue reveals that, on
|
|
entry, it saves the PC(+12), SP(+8), and R1(+4) registers
|
|
(decrementing the SP by 12). Consequently, the value of the PC
|
|
register in the previous frame is found in memory at SP+12, and
|
|
THIS frame's SP can be obtained by unwinding the NEXT frame's SP.
|
|
|
|
This function takes THIS_FRAME as an argument. It can find the
|
|
values of registers in THIS frame by calling get_frame_register
|
|
(THIS_FRAME), and reinvoke itself to find other registers in the
|
|
PREVIOUS frame by calling frame_unwind_register (THIS_FRAME).
|
|
|
|
The result is a GDB value object describing the register value. It
|
|
may be a lazy reference to memory, a lazy reference to the value of
|
|
a register in THIS frame, or a non-lvalue.
|
|
|
|
If the previous frame's register was not saved by THIS_FRAME and is
|
|
therefore undefined, return a wholly optimized-out not_lval value.
|
|
|
|
THIS_PROLOGUE_CACHE can be used to share any prolog analysis data
|
|
with the other unwind methods. Memory for that cache should be
|
|
allocated using FRAME_OBSTACK_ZALLOC(). */
|
|
|
|
typedef value *(frame_prev_register_ftype) (const frame_info_ptr &this_frame,
|
|
void **this_prologue_cache,
|
|
int regnum);
|
|
|
|
/* Deallocate extra memory associated with the frame cache if any. */
|
|
|
|
typedef void (frame_dealloc_cache_ftype) (frame_info *self,
|
|
void *this_cache);
|
|
|
|
/* Assuming the frame chain: (outer) prev <-> this <-> next (inner);
|
|
use THIS frame, and implicitly the NEXT frame's register unwind
|
|
method, return PREV frame's architecture. */
|
|
|
|
typedef gdbarch *(frame_prev_arch_ftype) (const frame_info_ptr &this_frame,
|
|
void **this_prologue_cache);
|
|
|
|
struct frame_unwind
|
|
{
|
|
const char *name;
|
|
/* The frame's type. Should this instead be a collection of
|
|
predicates that test the frame for various attributes? */
|
|
enum frame_type type;
|
|
/* Should an attribute indicating the frame's address-in-block go
|
|
here? */
|
|
frame_unwind_stop_reason_ftype *stop_reason;
|
|
frame_this_id_ftype *this_id;
|
|
frame_prev_register_ftype *prev_register;
|
|
const struct frame_data *unwind_data;
|
|
frame_sniffer_ftype *sniffer;
|
|
frame_dealloc_cache_ftype *dealloc_cache;
|
|
frame_prev_arch_ftype *prev_arch;
|
|
};
|
|
|
|
/* Register a frame unwinder, _prepending_ it to the front of the
|
|
search list (so it is sniffed before previously registered
|
|
unwinders). By using a prepend, later calls can install unwinders
|
|
that override earlier calls. This allows, for instance, an OSABI
|
|
to install a more specific sigtramp unwinder that overrides the
|
|
traditional brute-force unwinder. */
|
|
extern void frame_unwind_prepend_unwinder (struct gdbarch *,
|
|
const struct frame_unwind *);
|
|
|
|
/* Add a frame sniffer to the list. The predicates are polled in the
|
|
order that they are appended. The initial list contains the dummy
|
|
frame sniffer. */
|
|
|
|
extern void frame_unwind_append_unwinder (struct gdbarch *gdbarch,
|
|
const struct frame_unwind *unwinder);
|
|
|
|
/* Iterate through sniffers for THIS_FRAME frame until one returns with an
|
|
unwinder implementation. THIS_FRAME->UNWIND must be NULL, it will get set
|
|
by this function. Possibly initialize THIS_CACHE. */
|
|
|
|
extern void frame_unwind_find_by_frame (const frame_info_ptr &this_frame,
|
|
void **this_cache);
|
|
|
|
/* Helper functions for value-based register unwinding. These return
|
|
a (possibly lazy) value of the appropriate type. */
|
|
|
|
/* Return a value which indicates that FRAME did not save REGNUM. */
|
|
|
|
value *frame_unwind_got_optimized (const frame_info_ptr &frame, int regnum);
|
|
|
|
/* Return a value which indicates that FRAME copied REGNUM into
|
|
register NEW_REGNUM. */
|
|
|
|
value *frame_unwind_got_register (const frame_info_ptr &frame, int regnum,
|
|
int new_regnum);
|
|
|
|
/* Return a value which indicates that FRAME saved REGNUM in memory at
|
|
ADDR. */
|
|
|
|
value *frame_unwind_got_memory (const frame_info_ptr &frame, int regnum,
|
|
CORE_ADDR addr);
|
|
|
|
/* Return a value which indicates that FRAME's saved version of
|
|
REGNUM has a known constant (computed) value of VAL. */
|
|
|
|
value *frame_unwind_got_constant (const frame_info_ptr &frame, int regnum,
|
|
ULONGEST val);
|
|
|
|
/* Return a value which indicates that FRAME's saved version of
|
|
REGNUM has a known constant (computed) value which is stored
|
|
inside BUF. */
|
|
|
|
value *frame_unwind_got_bytes (const frame_info_ptr &frame, int regnum,
|
|
const gdb_byte *buf);
|
|
|
|
/* Return a value which indicates that FRAME's saved version of REGNUM
|
|
has a known constant (computed) value of ADDR. Convert the
|
|
CORE_ADDR to a target address if necessary. */
|
|
|
|
value *frame_unwind_got_address (const frame_info_ptr &frame, int regnum,
|
|
CORE_ADDR addr);
|
|
|
|
#endif
|