/* Definitions for a frame unwinder, for GDB, the GNU debugger.
- Copyright 2003 Free Software Foundation, Inc.
+ 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 2 of the License, or
+ 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,
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. */
+ 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;
-/* Return the frame unwind methods for the function that contains PC,
- or NULL if this this unwinder can't handle this frame. */
+#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);
-typedef const struct frame_unwind *(frame_unwind_p_ftype) (CORE_ADDR pc);
-
-/* Add a frame unwinder to the list. The predicates are polled in the
- order that they are appended. The initial list contains the dummy
- frame's predicate. */
-
-extern void frame_unwind_append_predicate (struct gdbarch *gdbarch,
- frame_unwind_p_ftype *p);
-
-/* Iterate through the list of frame unwinders until one returns an
- implementation. */
-
-extern const struct frame_unwind *frame_unwind_find_by_pc (struct gdbarch
- *gdbarch,
- CORE_ADDR pc);
+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;
+};
-/* Return the location (and possibly value) of REGNUM for the previous
- (older, up) frame. All parameters except VALUEP can be assumed to
- be non NULL. When VALUEP is NULL, just the location of the
- register should be returned.
+/* 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);
- UNWIND_CACHE is provided as mechanism for implementing a per-frame
- local cache. It's initial value being NULL. Memory for that cache
- should be allocated using frame_obstack_zalloc().
+/* 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. */
- Register window architectures (eg SPARC) should note that REGNUM
- identifies the register for the previous frame. For instance, a
- request for the value of "o1" for the previous frame would be found
- in the register "i1" in this FRAME. */
+typedef const struct frame_unwind *(frame_unwind_sniffer_ftype) (struct frame_info *next_frame);
-typedef void (frame_unwind_reg_ftype) (struct frame_info * frame,
- void **unwind_cache,
- int regnum,
- int *optimized,
- enum lval_type * lvalp,
- CORE_ADDR *addrp,
- int *realnump, void *valuep);
+/* 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. */
-/* Same as for registers above, but return the ID of the frame that
- called this one. */
+extern void frame_unwind_append_sniffer (struct gdbarch *gdbarch,
+ frame_unwind_sniffer_ftype *sniffer);
-typedef void (frame_unwind_id_ftype) (struct frame_info * frame,
- void **unwind_cache,
- struct frame_id * id);
+/* Iterate through the next frame's sniffers until one returns with an
+ unwinder implementation. Possibly initialize THIS_CACHE. */
-struct frame_unwind
-{
- /* Should the frame's type go here? */
- /* Should an attribute indicating the frame's address-in-block go
- here? */
- frame_unwind_id_ftype *id;
- frame_unwind_reg_ftype *reg;
-};
+extern const struct frame_unwind *frame_unwind_find_by_frame (struct frame_info *next_frame,
+ void **this_cache);
#endif
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