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[/] [openrisc/] [trunk/] [gnu-src/] [gdb-6.8/] [gdb/] [frame-unwind.h] - Blame information for rev 157

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1 24 jeremybenn
/* Definitions for a frame unwinder, for GDB, the GNU debugger.
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   Copyright (C) 2003, 2004, 2007, 2008 Free Software Foundation, Inc.
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   This file is part of GDB.
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   This program is free software; you can redistribute it and/or modify
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   it under the terms of the GNU General Public License as published by
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   the Free Software Foundation; either version 3 of the License, or
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   (at your option) any later version.
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   This program is distributed in the hope that it will be useful,
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   but WITHOUT ANY WARRANTY; without even the implied warranty of
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   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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   GNU General Public License for more details.
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   You should have received a copy of the GNU General Public License
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   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
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#if !defined (FRAME_UNWIND_H)
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#define FRAME_UNWIND_H 1
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struct frame_data;
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struct frame_info;
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struct frame_id;
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struct frame_unwind;
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struct gdbarch;
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struct regcache;
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#include "frame.h"              /* For enum frame_type.  */
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/* The following unwind functions assume a chain of frames forming the
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   sequence: (outer) prev <-> this <-> next (inner).  All the
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   functions are called with called with the next frame's `struct
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   frame_info' and and this frame's prologue cache.
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   THIS frame's register values can be obtained by unwinding NEXT
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   frame's registers (a recursive operation).
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   THIS frame's prologue cache can be used to cache information such
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   as where this frame's prologue stores the previous frame's
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   registers.  */
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/* Given the NEXT frame, take a wiff of THIS frame's registers (namely
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   the PC and attributes) and if SELF is the applicable unwinder,
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   return non-zero.  Possibly also initialize THIS_PROLOGUE_CACHE.  */
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typedef int (frame_sniffer_ftype) (const struct frame_unwind *self,
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                                   struct frame_info *next_frame,
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                                   void **this_prologue_cache);
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/* Assuming the frame chain: (outer) prev <-> this <-> next (inner);
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   use the NEXT frame, and its register unwind method, to determine
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   the frame ID of THIS frame.
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   A frame ID provides an invariant that can be used to re-identify an
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   instance of a frame.  It is a combination of the frame's `base' and
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   the frame's function's code address.
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   Traditionally, THIS frame's ID was determined by examining THIS
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   frame's function's prologue, and identifying the register/offset
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   used as THIS frame's base.
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   Example: An examination of THIS frame's prologue reveals that, on
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   entry, it saves the PC(+12), SP(+8), and R1(+4) registers
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   (decrementing the SP by 12).  Consequently, the frame ID's base can
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   be determined by adding 12 to the THIS frame's stack-pointer, and
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   the value of THIS frame's SP can be obtained by unwinding the NEXT
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   frame's SP.
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   THIS_PROLOGUE_CACHE can be used to share any prolog analysis data
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   with the other unwind methods.  Memory for that cache should be
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   allocated using FRAME_OBSTACK_ZALLOC().  */
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typedef void (frame_this_id_ftype) (struct frame_info *next_frame,
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                                    void **this_prologue_cache,
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                                    struct frame_id *this_id);
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/* Assuming the frame chain: (outer) prev <-> this <-> next (inner);
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   use the NEXT frame, and its register unwind method, to unwind THIS
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   frame's registers (returning the value of the specified register
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   REGNUM in the previous frame).
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   Traditionally, THIS frame's registers were unwound by examining
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   THIS frame's function's prologue and identifying which registers
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   that prolog code saved on the stack.
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   Example: An examination of THIS frame's prologue reveals that, on
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   entry, it saves the PC(+12), SP(+8), and R1(+4) registers
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   (decrementing the SP by 12).  Consequently, the value of the PC
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   register in the previous frame is found in memory at SP+12, and
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   THIS frame's SP can be obtained by unwinding the NEXT frame's SP.
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   Why not pass in THIS_FRAME?  By passing in NEXT frame and THIS
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   cache, the supplied parameters are consistent with the sibling
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   function THIS_ID.
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   Can the code call ``frame_register (get_prev_frame (NEXT_FRAME))''?
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   Won't the call frame_register (THIS_FRAME) be faster?  Well,
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   ignoring the possability that the previous frame does not yet
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   exist, the ``frame_register (FRAME)'' function is expanded to
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   ``frame_register_unwind (get_next_frame (FRAME)'' and hence that
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   call will expand to ``frame_register_unwind (get_next_frame
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   (get_prev_frame (NEXT_FRAME)))''.  Might as well call
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   ``frame_register_unwind (NEXT_FRAME)'' directly.
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   THIS_PROLOGUE_CACHE can be used to share any prolog analysis data
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   with the other unwind methods.  Memory for that cache should be
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   allocated using FRAME_OBSTACK_ZALLOC().  */
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typedef void (frame_prev_register_ftype) (struct frame_info *next_frame,
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                                          void **this_prologue_cache,
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                                          int prev_regnum,
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                                          int *optimized,
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                                          enum lval_type * lvalp,
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                                          CORE_ADDR *addrp,
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                                          int *realnump, gdb_byte *valuep);
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/* Assuming the frame chain: (outer) prev <-> this <-> next (inner);
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   use the NEXT frame, and its register unwind method, to return the PREV
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   frame's program-counter.  */
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typedef CORE_ADDR (frame_prev_pc_ftype) (struct frame_info *next_frame,
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                                         void **this_prologue_cache);
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/* Deallocate extra memory associated with the frame cache if any.  */
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typedef void (frame_dealloc_cache_ftype) (struct frame_info *self,
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                                          void *this_cache);
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struct frame_unwind
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{
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  /* The frame's type.  Should this instead be a collection of
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     predicates that test the frame for various attributes?  */
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  enum frame_type type;
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  /* Should an attribute indicating the frame's address-in-block go
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     here?  */
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  frame_this_id_ftype *this_id;
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  frame_prev_register_ftype *prev_register;
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  const struct frame_data *unwind_data;
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  frame_sniffer_ftype *sniffer;
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  frame_prev_pc_ftype *prev_pc;
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  frame_dealloc_cache_ftype *dealloc_cache;
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};
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/* Register a frame unwinder, _prepending_ it to the front of the
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   search list (so it is sniffed before previously registered
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   unwinders).  By using a prepend, later calls can install unwinders
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   that override earlier calls.  This allows, for instance, an OSABI
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   to install a a more specific sigtramp unwinder that overrides the
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   traditional brute-force unwinder.  */
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extern void frame_unwind_prepend_unwinder (struct gdbarch *gdbarch,
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                                           const struct frame_unwind *unwinder);
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/* Given the NEXT frame, take a wiff of THIS frame's registers (namely
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   the PC and attributes) and if it is the applicable unwinder return
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   the unwind methods, or NULL if it is not.  */
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typedef const struct frame_unwind *(frame_unwind_sniffer_ftype) (struct frame_info *next_frame);
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/* Add a frame sniffer to the list.  The predicates are polled in the
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   order that they are appended.  The initial list contains the dummy
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   frame sniffer.  */
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extern void frame_unwind_append_sniffer (struct gdbarch *gdbarch,
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                                         frame_unwind_sniffer_ftype *sniffer);
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/* Iterate through the next frame's sniffers until one returns with an
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   unwinder implementation.  Possibly initialize THIS_CACHE.  */
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extern const struct frame_unwind *frame_unwind_find_by_frame (struct frame_info *next_frame,
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                                                              void **this_cache);
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#endif

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