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

   Copyright (C) 2003, 2004, 2007, 2008, 2009, 2010

   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;

struct value;

#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 the next frame's `struct frame_info'

   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 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.  */

typedef int (frame_sniffer_ftype) (const struct frame_unwind *self,

                                   struct frame_info *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,

                           struct frame_info *this_frame,

                           void **this_prologue_cache);

/* 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) (struct frame_info *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.

   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 struct value * (frame_prev_register_ftype)

  (struct frame_info *this_frame, void **this_prologue_cache,

   int regnum);

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

typedef void (frame_dealloc_cache_ftype) (struct 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 struct gdbarch *(frame_prev_arch_ftype) (struct frame_info *this_frame,

                                                 void **this_prologue_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_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 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);

/* 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 until one returns with an

   unwinder implementation.  Possibly initialize THIS_CACHE.  */

extern const struct frame_unwind *frame_unwind_find_by_frame (struct frame_info *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.  */

struct value *frame_unwind_got_optimized (struct frame_info *frame,

                                          int regnum);

/* Return a value which indicates that FRAME copied REGNUM into

   register NEW_REGNUM.  */

struct value *frame_unwind_got_register (struct frame_info *frame, int regnum,

                                         int new_regnum);

/* Return a value which indicates that FRAME saved REGNUM in memory at

   ADDR.  */

struct value *frame_unwind_got_memory (struct frame_info *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.  */

struct value *frame_unwind_got_constant (struct frame_info *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.  */

struct value *frame_unwind_got_bytes (struct frame_info *frame, int regnum,

                                      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.  */

struct value *frame_unwind_got_address (struct frame_info *frame, int regnum,

                                        CORE_ADDR addr);

#endif