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Diffstat (limited to 'contrib/gdb/gdb/frame-unwind.h')
| -rw-r--r-- | contrib/gdb/gdb/frame-unwind.h | 141 |
1 files changed, 141 insertions, 0 deletions
diff --git a/contrib/gdb/gdb/frame-unwind.h b/contrib/gdb/gdb/frame-unwind.h new file mode 100644 index 0000000..8d17280 --- /dev/null +++ b/contrib/gdb/gdb/frame-unwind.h @@ -0,0 +1,141 @@ +/* Definitions for a frame unwinder, for GDB, the GNU debugger. + + Copyright 2003 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. */ + +#if !defined (FRAME_UNWIND_H) +#define FRAME_UNWIND_H 1 + +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. */ + +/* 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, void *valuep); + +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; +}; + +/* 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. */ + +extern const struct frame_unwind *frame_unwind_find_by_frame (struct frame_info *next_frame); + +#endif |
