[deliverable/binutils-gdb.git] / gdb / frame-unwind.h

/* Definitions for a frame unwinder, for GDB, the GNU debugger.

   Copyright (C) 2003, 2004, 2007 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;
struct frame_info;
struct frame_id;
struct frame_unwind;
struct gdbarch;
struct regcache;

#include "frame.h"		/* For enum frame_type.  */

/* The following unwind functions assume a chain of frames forming the
   sequence: (outer) prev <-> this <-> next (inner).  All the
   functions are called with called with the next frame's `struct
   frame_info' and and this frame's 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 the NEXT frame, take a wiff of THIS frame's registers (namely
   the PC and attributes) and if SELF is the applicable unwinder,
   return non-zero.  Possibly also initialize THIS_PROLOGUE_CACHE.  */

typedef int (frame_sniffer_ftype) (const struct frame_unwind *self,
				   struct frame_info *next_frame,
				   void **this_prologue_cache);

/* Assuming the frame chain: (outer) prev <-> this <-> next (inner);
   use the NEXT frame, and its 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) (struct frame_info *next_frame,
				    void **this_prologue_cache,
				    struct frame_id *this_id);

/* Assuming the frame chain: (outer) prev <-> this <-> next (inner);
   use the NEXT frame, and its 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.

   Why not pass in THIS_FRAME?  By passing in NEXT frame and THIS
   cache, the supplied parameters are consistent with the sibling
   function THIS_ID.

   Can the code call ``frame_register (get_prev_frame (NEXT_FRAME))''?
   Won't the call frame_register (THIS_FRAME) be faster?  Well,
   ignoring the possability that the previous frame does not yet
   exist, the ``frame_register (FRAME)'' function is expanded to
   ``frame_register_unwind (get_next_frame (FRAME)'' and hence that
   call will expand to ``frame_register_unwind (get_next_frame
   (get_prev_frame (NEXT_FRAME)))''.  Might as well call
   ``frame_register_unwind (NEXT_FRAME)'' directly.

   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_prev_register_ftype) (struct frame_info *next_frame,
					  void **this_prologue_cache,
					  int prev_regnum,
					  int *optimized,
					  enum lval_type * lvalp,
					  CORE_ADDR *addrp,
					  int *realnump, gdb_byte *valuep);

/* Assuming the frame chain: (outer) prev <-> this <-> next (inner);
   use the NEXT frame, and its register unwind method, to return the PREV
   frame's program-counter.  */

typedef CORE_ADDR (frame_prev_pc_ftype) (struct frame_info *next_frame,
					 void **this_prologue_cache);

/* Deallocate extra memory associated with the frame cache if any.  */

typedef void (frame_dealloc_cache_ftype) (struct frame_info *self,
					  void *this_cache);

struct frame_unwind
{
  /* 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_this_id_ftype *this_id;
  frame_prev_register_ftype *prev_register;
  const struct frame_data *unwind_data;
  frame_sniffer_ftype *sniffer;
  frame_prev_pc_ftype *prev_pc;
  frame_dealloc_cache_ftype *dealloc_cache;
};

/* 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 a more specific sigtramp unwinder that overrides the
   traditional brute-force unwinder.  */
extern void frame_unwind_prepend_unwinder (struct gdbarch *gdbarch,
					   const struct frame_unwind *unwinder);

/* Given the NEXT frame, take a wiff of THIS frame's registers (namely
   the PC and attributes) and if it is the applicable unwinder return
   the unwind methods, or NULL if it is not.  */

typedef const struct frame_unwind *(frame_unwind_sniffer_ftype) (struct frame_info *next_frame);

/* 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_sniffer (struct gdbarch *gdbarch,
					 frame_unwind_sniffer_ftype *sniffer);

/* Iterate through the next frame's sniffers until one returns with an
   unwinder implementation.  Possibly initialize THIS_CACHE.  */

extern const struct frame_unwind *frame_unwind_find_by_frame (struct frame_info *next_frame,
							      void **this_cache);

#endif
Commit	Line	Data
494cca16 AC	1	/* Definitions for a frame unwinder, for GDB, the GNU debugger.
494cca16 AC	2
6aba47ca	3	Copyright (C) 2003, 2004, 2007 Free Software Foundation, Inc.
494cca16 AC	4
	5	This file is part of GDB.
	6
	7	This program is free software; you can redistribute it and/or modify
	8	it under the terms of the GNU General Public License as published by
a9762ec7	9	the Free Software Foundation; either version 3 of the License, or
494cca16 AC	10	(at your option) any later version.
	11
	12	This program is distributed in the hope that it will be useful,
	13	but WITHOUT ANY WARRANTY; without even the implied warranty of
	14	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	15	GNU General Public License for more details.
	16
	17	You should have received a copy of the GNU General Public License
a9762ec7	18	along with this program. If not, see <http://www.gnu.org/licenses/>. */
494cca16 AC	19
	20	#if !defined (FRAME_UNWIND_H)
	21	#define FRAME_UNWIND_H 1
	22
82417da5	23	struct frame_data;
494cca16 AC	24	struct frame_info;
	25	struct frame_id;
	26	struct frame_unwind;
	27	struct gdbarch;
	28	struct regcache;
	29
7df05f2b AC	30	#include "frame.h" /* For enum frame_type. */
7df05f2b AC	31
6dc42492 AC	32	/* The following unwind functions assume a chain of frames forming the
	33	sequence: (outer) prev <-> this <-> next (inner). All the
	34	functions are called with called with the next frame's `struct
	35	frame_info' and and this frame's prologue cache.
	36
	37	THIS frame's register values can be obtained by unwinding NEXT
	38	frame's registers (a recursive operation).
	39
	40	THIS frame's prologue cache can be used to cache information such
	41	as where this frame's prologue stores the previous frame's
	42	registers. */
	43
82417da5 AC	44	/* Given the NEXT frame, take a wiff of THIS frame's registers (namely
	45	the PC and attributes) and if SELF is the applicable unwinder,
	46	return non-zero. Possibly also initialize THIS_PROLOGUE_CACHE. */
	47
	48	typedef int (frame_sniffer_ftype) (const struct frame_unwind *self,
	49	struct frame_info *next_frame,
	50	void **this_prologue_cache);
	51
6dc42492 AC	52	/* Assuming the frame chain: (outer) prev <-> this <-> next (inner);
	53	use the NEXT frame, and its register unwind method, to determine
	54	the frame ID of THIS frame.
	55
	56	A frame ID provides an invariant that can be used to re-identify an
	57	instance of a frame. It is a combination of the frame's `base' and
	58	the frame's function's code address.
	59
	60	Traditionally, THIS frame's ID was determined by examining THIS
	61	frame's function's prologue, and identifying the register/offset
	62	used as THIS frame's base.
	63
	64	Example: An examination of THIS frame's prologue reveals that, on
	65	entry, it saves the PC(+12), SP(+8), and R1(+4) registers
	66	(decrementing the SP by 12). Consequently, the frame ID's base can
	67	be determined by adding 12 to the THIS frame's stack-pointer, and
	68	the value of THIS frame's SP can be obtained by unwinding the NEXT
	69	frame's SP.
	70
	71	THIS_PROLOGUE_CACHE can be used to share any prolog analysis data
	72	with the other unwind methods. Memory for that cache should be
35d5d4ee	73	allocated using FRAME_OBSTACK_ZALLOC(). */
6dc42492 AC	74
	75	typedef void (frame_this_id_ftype) (struct frame_info *next_frame,
	76	void **this_prologue_cache,
	77	struct frame_id *this_id);
	78
	79	/* Assuming the frame chain: (outer) prev <-> this <-> next (inner);
	80	use the NEXT frame, and its register unwind method, to unwind THIS
	81	frame's registers (returning the value of the specified register
	82	REGNUM in the previous frame).
	83
	84	Traditionally, THIS frame's registers were unwound by examining
	85	THIS frame's function's prologue and identifying which registers
	86	that prolog code saved on the stack.
	87
	88	Example: An examination of THIS frame's prologue reveals that, on
	89	entry, it saves the PC(+12), SP(+8), and R1(+4) registers
	90	(decrementing the SP by 12). Consequently, the value of the PC
	91	register in the previous frame is found in memory at SP+12, and
	92	THIS frame's SP can be obtained by unwinding the NEXT frame's SP.
	93
	94	Why not pass in THIS_FRAME? By passing in NEXT frame and THIS
	95	cache, the supplied parameters are consistent with the sibling
	96	function THIS_ID.
	97
	98	Can the code call ``frame_register (get_prev_frame (NEXT_FRAME))''?
	99	Won't the call frame_register (THIS_FRAME) be faster? Well,
	100	ignoring the possability that the previous frame does not yet
	101	exist, the ``frame_register (FRAME)'' function is expanded to
	102	``frame_register_unwind (get_next_frame (FRAME)'' and hence that
	103	call will expand to ``frame_register_unwind (get_next_frame
	104	(get_prev_frame (NEXT_FRAME)))''. Might as well call
	105	``frame_register_unwind (NEXT_FRAME)'' directly.
	106
	107	THIS_PROLOGUE_CACHE can be used to share any prolog analysis data
	108	with the other unwind methods. Memory for that cache should be
35d5d4ee	109	allocated using FRAME_OBSTACK_ZALLOC(). */
6dc42492 AC	110
	111	typedef void (frame_prev_register_ftype) (struct frame_info *next_frame,
	112	void **this_prologue_cache,
	113	int prev_regnum,
	114	int *optimized,
	115	enum lval_type * lvalp,
	116	CORE_ADDR *addrp,
10c42a71	117	int realnump, gdb_byte valuep);
494cca16	118
cbafadeb AC	119	/* Assuming the frame chain: (outer) prev <-> this <-> next (inner);
	120	use the NEXT frame, and its register unwind method, to return the PREV
	121	frame's program-counter. */
	122
	123	typedef CORE_ADDR (frame_prev_pc_ftype) (struct frame_info *next_frame,
	124	void **this_prologue_cache);
	125
272dfcfd AS	126	/* Deallocate extra memory associated with the frame cache if any. */
	127
	128	typedef void (frame_dealloc_cache_ftype) (struct frame_info *self,
	129	void *this_cache);
cbafadeb	130
494cca16 AC	131	struct frame_unwind
494cca16 AC	132	{
7df05f2b AC	133	/* The frame's type. Should this instead be a collection of
	134	predicates that test the frame for various attributes? */
	135	enum frame_type type;
494cca16 AC	136	/* Should an attribute indicating the frame's address-in-block go
494cca16 AC	137	here? */
6dc42492 AC	138	frame_this_id_ftype *this_id;
6dc42492 AC	139	frame_prev_register_ftype *prev_register;
82417da5 AC	140	const struct frame_data *unwind_data;
82417da5 AC	141	frame_sniffer_ftype *sniffer;
cbafadeb	142	frame_prev_pc_ftype *prev_pc;
272dfcfd	143	frame_dealloc_cache_ftype *dealloc_cache;
494cca16 AC	144	};
494cca16 AC	145
fb2be677 AC	146	/* Register a frame unwinder, _prepending_ it to the front of the
	147	search list (so it is sniffed before previously registered
	148	unwinders). By using a prepend, later calls can install unwinders
	149	that override earlier calls. This allows, for instance, an OSABI
	150	to install a a more specific sigtramp unwinder that overrides the
	151	traditional brute-force unwinder. */
	152	extern void frame_unwind_prepend_unwinder (struct gdbarch *gdbarch,
	153	const struct frame_unwind *unwinder);
82417da5	154
e8a89fe2 AC	155	/* Given the NEXT frame, take a wiff of THIS frame's registers (namely
	156	the PC and attributes) and if it is the applicable unwinder return
	157	the unwind methods, or NULL if it is not. */
	158
	159	typedef const struct frame_unwind (frame_unwind_sniffer_ftype) (struct frame_info next_frame);
	160
	161	/* Add a frame sniffer to the list. The predicates are polled in the
	162	order that they are appended. The initial list contains the dummy
	163	frame sniffer. */
	164
	165	extern void frame_unwind_append_sniffer (struct gdbarch *gdbarch,
	166	frame_unwind_sniffer_ftype *sniffer);
	167
	168	/* Iterate through the next frame's sniffers until one returns with an
82417da5	169	unwinder implementation. Possibly initialize THIS_CACHE. */
e8a89fe2	170
82417da5 AC	171	extern const struct frame_unwind frame_unwind_find_by_frame (struct frame_info next_frame,
82417da5 AC	172	void **this_cache);
e8a89fe2	173
494cca16	174	#endif