1 /* Cache and manage frames for GDB, the GNU debugger.
3 Copyright (C) 1986, 1987, 1989, 1991, 1994, 1995, 1996, 1998, 2000, 2001,
4 2002, 2003, 2004, 2007, 2008, 2009, 2010, 2011
5 Free Software Foundation, Inc.
7 This file is part of GDB.
9 This program is free software; you can redistribute it and/or modify
10 it under the terms of the GNU General Public License as published by
11 the Free Software Foundation; either version 3 of the License, or
12 (at your option) any later version.
14 This program is distributed in the hope that it will be useful,
15 but WITHOUT ANY WARRANTY; without even the implied warranty of
16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 GNU General Public License for more details.
19 You should have received a copy of the GNU General Public License
20 along with this program. If not, see <http://www.gnu.org/licenses/>. */
26 #include "inferior.h" /* for inferior_ptid */
28 #include "gdb_assert.h"
29 #include "gdb_string.h"
30 #include "user-regs.h"
31 #include "gdb_obstack.h"
32 #include "dummy-frame.h"
33 #include "sentinel-frame.h"
37 #include "frame-unwind.h"
38 #include "frame-base.h"
43 #include "exceptions.h"
44 #include "gdbthread.h"
46 #include "inline-frame.h"
47 #include "tracepoint.h"
49 static struct frame_info *get_prev_frame_1 (struct frame_info *this_frame);
50 static struct frame_info *get_prev_frame_raw (struct frame_info *this_frame);
52 /* We keep a cache of stack frames, each of which is a "struct
53 frame_info". The innermost one gets allocated (in
54 wait_for_inferior) each time the inferior stops; current_frame
55 points to it. Additional frames get allocated (in get_prev_frame)
56 as needed, and are chained through the next and prev fields. Any
57 time that the frame cache becomes invalid (most notably when we
58 execute something, but also if we change how we interpret the
59 frames (e.g. "set heuristic-fence-post" in mips-tdep.c, or anything
60 which reads new symbols)), we should call reinit_frame_cache. */
64 /* Level of this frame. The inner-most (youngest) frame is at level
65 0. As you move towards the outer-most (oldest) frame, the level
66 increases. This is a cached value. It could just as easily be
67 computed by counting back from the selected frame to the inner
69 /* NOTE: cagney/2002-04-05: Perhaps a level of ``-1'' should be
70 reserved to indicate a bogus frame - one that has been created
71 just to keep GDB happy (GDB always needs a frame). For the
72 moment leave this as speculation. */
75 /* The frame's program space. */
76 struct program_space *pspace;
78 /* The frame's address space. */
79 struct address_space *aspace;
81 /* The frame's low-level unwinder and corresponding cache. The
82 low-level unwinder is responsible for unwinding register values
83 for the previous frame. The low-level unwind methods are
84 selected based on the presence, or otherwise, of register unwind
85 information such as CFI. */
87 const struct frame_unwind *unwind;
89 /* Cached copy of the previous frame's architecture. */
96 /* Cached copy of the previous frame's resume address. */
102 /* Cached copy of the previous frame's function address. */
109 /* This frame's ID. */
113 struct frame_id value;
116 /* The frame's high-level base methods, and corresponding cache.
117 The high level base methods are selected based on the frame's
119 const struct frame_base *base;
122 /* Pointers to the next (down, inner, younger) and previous (up,
123 outer, older) frame_info's in the frame cache. */
124 struct frame_info *next; /* down, inner, younger */
126 struct frame_info *prev; /* up, outer, older */
128 /* The reason why we could not set PREV, or UNWIND_NO_REASON if we
129 could. Only valid when PREV_P is set. */
130 enum unwind_stop_reason stop_reason;
133 /* A frame stash used to speed up frame lookups. */
135 /* We currently only stash one frame at a time, as this seems to be
136 sufficient for now. */
137 static struct frame_info *frame_stash = NULL;
139 /* Add the following FRAME to the frame stash. */
142 frame_stash_add (struct frame_info *frame)
147 /* Search the frame stash for an entry with the given frame ID.
148 If found, return that frame. Otherwise return NULL. */
150 static struct frame_info *
151 frame_stash_find (struct frame_id id)
153 if (frame_stash && frame_id_eq (frame_stash->this_id.value, id))
159 /* Invalidate the frame stash by removing all entries in it. */
162 frame_stash_invalidate (void)
167 /* Flag to control debugging. */
171 show_frame_debug (struct ui_file *file, int from_tty,
172 struct cmd_list_element *c, const char *value)
174 fprintf_filtered (file, _("Frame debugging is %s.\n"), value);
177 /* Flag to indicate whether backtraces should stop at main et.al. */
179 static int backtrace_past_main;
181 show_backtrace_past_main (struct ui_file *file, int from_tty,
182 struct cmd_list_element *c, const char *value)
184 fprintf_filtered (file,
185 _("Whether backtraces should "
186 "continue past \"main\" is %s.\n"),
190 static int backtrace_past_entry;
192 show_backtrace_past_entry (struct ui_file *file, int from_tty,
193 struct cmd_list_element *c, const char *value)
195 fprintf_filtered (file, _("Whether backtraces should continue past the "
196 "entry point of a program is %s.\n"),
200 static int backtrace_limit = INT_MAX;
202 show_backtrace_limit (struct ui_file *file, int from_tty,
203 struct cmd_list_element *c, const char *value)
205 fprintf_filtered (file,
206 _("An upper bound on the number "
207 "of backtrace levels is %s.\n"),
213 fprint_field (struct ui_file *file, const char *name, int p, CORE_ADDR addr)
216 fprintf_unfiltered (file, "%s=%s", name, hex_string (addr));
218 fprintf_unfiltered (file, "!%s", name);
222 fprint_frame_id (struct ui_file *file, struct frame_id id)
224 fprintf_unfiltered (file, "{");
225 fprint_field (file, "stack", id.stack_addr_p, id.stack_addr);
226 fprintf_unfiltered (file, ",");
227 fprint_field (file, "code", id.code_addr_p, id.code_addr);
228 fprintf_unfiltered (file, ",");
229 fprint_field (file, "special", id.special_addr_p, id.special_addr);
231 fprintf_unfiltered (file, ",inlined=%d", id.inline_depth);
232 fprintf_unfiltered (file, "}");
236 fprint_frame_type (struct ui_file *file, enum frame_type type)
241 fprintf_unfiltered (file, "NORMAL_FRAME");
244 fprintf_unfiltered (file, "DUMMY_FRAME");
247 fprintf_unfiltered (file, "INLINE_FRAME");
250 fprintf_unfiltered (file, "SENTINEL_FRAME");
253 fprintf_unfiltered (file, "SIGTRAMP_FRAME");
256 fprintf_unfiltered (file, "ARCH_FRAME");
259 fprintf_unfiltered (file, "<unknown type>");
265 fprint_frame (struct ui_file *file, struct frame_info *fi)
269 fprintf_unfiltered (file, "<NULL frame>");
272 fprintf_unfiltered (file, "{");
273 fprintf_unfiltered (file, "level=%d", fi->level);
274 fprintf_unfiltered (file, ",");
275 fprintf_unfiltered (file, "type=");
276 if (fi->unwind != NULL)
277 fprint_frame_type (file, fi->unwind->type);
279 fprintf_unfiltered (file, "<unknown>");
280 fprintf_unfiltered (file, ",");
281 fprintf_unfiltered (file, "unwind=");
282 if (fi->unwind != NULL)
283 gdb_print_host_address (fi->unwind, file);
285 fprintf_unfiltered (file, "<unknown>");
286 fprintf_unfiltered (file, ",");
287 fprintf_unfiltered (file, "pc=");
288 if (fi->next != NULL && fi->next->prev_pc.p)
289 fprintf_unfiltered (file, "%s", hex_string (fi->next->prev_pc.value));
291 fprintf_unfiltered (file, "<unknown>");
292 fprintf_unfiltered (file, ",");
293 fprintf_unfiltered (file, "id=");
295 fprint_frame_id (file, fi->this_id.value);
297 fprintf_unfiltered (file, "<unknown>");
298 fprintf_unfiltered (file, ",");
299 fprintf_unfiltered (file, "func=");
300 if (fi->next != NULL && fi->next->prev_func.p)
301 fprintf_unfiltered (file, "%s", hex_string (fi->next->prev_func.addr));
303 fprintf_unfiltered (file, "<unknown>");
304 fprintf_unfiltered (file, "}");
307 /* Given FRAME, return the enclosing normal frame for inlined
308 function frames. Otherwise return the original frame. */
310 static struct frame_info *
311 skip_inlined_frames (struct frame_info *frame)
313 while (get_frame_type (frame) == INLINE_FRAME)
314 frame = get_prev_frame (frame);
319 /* Return a frame uniq ID that can be used to, later, re-find the
323 get_frame_id (struct frame_info *fi)
326 return null_frame_id;
331 fprintf_unfiltered (gdb_stdlog, "{ get_frame_id (fi=%d) ",
333 /* Find the unwinder. */
334 if (fi->unwind == NULL)
335 frame_unwind_find_by_frame (fi, &fi->prologue_cache);
336 /* Find THIS frame's ID. */
337 /* Default to outermost if no ID is found. */
338 fi->this_id.value = outer_frame_id;
339 fi->unwind->this_id (fi, &fi->prologue_cache, &fi->this_id.value);
340 gdb_assert (frame_id_p (fi->this_id.value));
344 fprintf_unfiltered (gdb_stdlog, "-> ");
345 fprint_frame_id (gdb_stdlog, fi->this_id.value);
346 fprintf_unfiltered (gdb_stdlog, " }\n");
350 frame_stash_add (fi);
352 return fi->this_id.value;
356 get_stack_frame_id (struct frame_info *next_frame)
358 return get_frame_id (skip_inlined_frames (next_frame));
362 frame_unwind_caller_id (struct frame_info *next_frame)
364 struct frame_info *this_frame;
366 /* Use get_prev_frame_1, and not get_prev_frame. The latter will truncate
367 the frame chain, leading to this function unintentionally
368 returning a null_frame_id (e.g., when a caller requests the frame
369 ID of "main()"s caller. */
371 next_frame = skip_inlined_frames (next_frame);
372 this_frame = get_prev_frame_1 (next_frame);
374 return get_frame_id (skip_inlined_frames (this_frame));
376 return null_frame_id;
379 const struct frame_id null_frame_id; /* All zeros. */
380 const struct frame_id outer_frame_id = { 0, 0, 0, 0, 0, 1, 0 };
383 frame_id_build_special (CORE_ADDR stack_addr, CORE_ADDR code_addr,
384 CORE_ADDR special_addr)
386 struct frame_id id = null_frame_id;
388 id.stack_addr = stack_addr;
390 id.code_addr = code_addr;
392 id.special_addr = special_addr;
393 id.special_addr_p = 1;
398 frame_id_build (CORE_ADDR stack_addr, CORE_ADDR code_addr)
400 struct frame_id id = null_frame_id;
402 id.stack_addr = stack_addr;
404 id.code_addr = code_addr;
410 frame_id_build_wild (CORE_ADDR stack_addr)
412 struct frame_id id = null_frame_id;
414 id.stack_addr = stack_addr;
420 frame_id_p (struct frame_id l)
424 /* The frame is valid iff it has a valid stack address. */
426 /* outer_frame_id is also valid. */
427 if (!p && memcmp (&l, &outer_frame_id, sizeof (l)) == 0)
431 fprintf_unfiltered (gdb_stdlog, "{ frame_id_p (l=");
432 fprint_frame_id (gdb_stdlog, l);
433 fprintf_unfiltered (gdb_stdlog, ") -> %d }\n", p);
439 frame_id_inlined_p (struct frame_id l)
444 return (l.inline_depth != 0);
448 frame_id_eq (struct frame_id l, struct frame_id r)
452 if (!l.stack_addr_p && l.special_addr_p
453 && !r.stack_addr_p && r.special_addr_p)
454 /* The outermost frame marker is equal to itself. This is the
455 dodgy thing about outer_frame_id, since between execution steps
456 we might step into another function - from which we can't
457 unwind either. More thought required to get rid of
460 else if (!l.stack_addr_p || !r.stack_addr_p)
461 /* Like a NaN, if either ID is invalid, the result is false.
462 Note that a frame ID is invalid iff it is the null frame ID. */
464 else if (l.stack_addr != r.stack_addr)
465 /* If .stack addresses are different, the frames are different. */
467 else if (l.code_addr_p && r.code_addr_p && l.code_addr != r.code_addr)
468 /* An invalid code addr is a wild card. If .code addresses are
469 different, the frames are different. */
471 else if (l.special_addr_p && r.special_addr_p
472 && l.special_addr != r.special_addr)
473 /* An invalid special addr is a wild card (or unused). Otherwise
474 if special addresses are different, the frames are different. */
476 else if (l.inline_depth != r.inline_depth)
477 /* If inline depths are different, the frames must be different. */
480 /* Frames are equal. */
485 fprintf_unfiltered (gdb_stdlog, "{ frame_id_eq (l=");
486 fprint_frame_id (gdb_stdlog, l);
487 fprintf_unfiltered (gdb_stdlog, ",r=");
488 fprint_frame_id (gdb_stdlog, r);
489 fprintf_unfiltered (gdb_stdlog, ") -> %d }\n", eq);
494 /* Safety net to check whether frame ID L should be inner to
495 frame ID R, according to their stack addresses.
497 This method cannot be used to compare arbitrary frames, as the
498 ranges of valid stack addresses may be discontiguous (e.g. due
501 However, it can be used as safety net to discover invalid frame
502 IDs in certain circumstances. Assuming that NEXT is the immediate
503 inner frame to THIS and that NEXT and THIS are both NORMAL frames:
505 * The stack address of NEXT must be inner-than-or-equal to the stack
508 Therefore, if frame_id_inner (THIS, NEXT) holds, some unwind
511 * If NEXT and THIS have different stack addresses, no other frame
512 in the frame chain may have a stack address in between.
514 Therefore, if frame_id_inner (TEST, THIS) holds, but
515 frame_id_inner (TEST, NEXT) does not hold, TEST cannot refer
516 to a valid frame in the frame chain.
518 The sanity checks above cannot be performed when a SIGTRAMP frame
519 is involved, because signal handlers might be executed on a different
520 stack than the stack used by the routine that caused the signal
521 to be raised. This can happen for instance when a thread exceeds
522 its maximum stack size. In this case, certain compilers implement
523 a stack overflow strategy that cause the handler to be run on a
527 frame_id_inner (struct gdbarch *gdbarch, struct frame_id l, struct frame_id r)
531 if (!l.stack_addr_p || !r.stack_addr_p)
532 /* Like NaN, any operation involving an invalid ID always fails. */
534 else if (l.inline_depth > r.inline_depth
535 && l.stack_addr == r.stack_addr
536 && l.code_addr_p == r.code_addr_p
537 && l.special_addr_p == r.special_addr_p
538 && l.special_addr == r.special_addr)
540 /* Same function, different inlined functions. */
541 struct block *lb, *rb;
543 gdb_assert (l.code_addr_p && r.code_addr_p);
545 lb = block_for_pc (l.code_addr);
546 rb = block_for_pc (r.code_addr);
548 if (lb == NULL || rb == NULL)
549 /* Something's gone wrong. */
552 /* This will return true if LB and RB are the same block, or
553 if the block with the smaller depth lexically encloses the
554 block with the greater depth. */
555 inner = contained_in (lb, rb);
558 /* Only return non-zero when strictly inner than. Note that, per
559 comment in "frame.h", there is some fuzz here. Frameless
560 functions are not strictly inner than (same .stack but
561 different .code and/or .special address). */
562 inner = gdbarch_inner_than (gdbarch, l.stack_addr, r.stack_addr);
565 fprintf_unfiltered (gdb_stdlog, "{ frame_id_inner (l=");
566 fprint_frame_id (gdb_stdlog, l);
567 fprintf_unfiltered (gdb_stdlog, ",r=");
568 fprint_frame_id (gdb_stdlog, r);
569 fprintf_unfiltered (gdb_stdlog, ") -> %d }\n", inner);
575 frame_find_by_id (struct frame_id id)
577 struct frame_info *frame, *prev_frame;
579 /* ZERO denotes the null frame, let the caller decide what to do
580 about it. Should it instead return get_current_frame()? */
581 if (!frame_id_p (id))
584 /* Try using the frame stash first. Finding it there removes the need
585 to perform the search by looping over all frames, which can be very
586 CPU-intensive if the number of frames is very high (the loop is O(n)
587 and get_prev_frame performs a series of checks that are relatively
588 expensive). This optimization is particularly useful when this function
589 is called from another function (such as value_fetch_lazy, case
590 VALUE_LVAL (val) == lval_register) which already loops over all frames,
591 making the overall behavior O(n^2). */
592 frame = frame_stash_find (id);
596 for (frame = get_current_frame (); ; frame = prev_frame)
598 struct frame_id this = get_frame_id (frame);
600 if (frame_id_eq (id, this))
601 /* An exact match. */
604 prev_frame = get_prev_frame (frame);
608 /* As a safety net to avoid unnecessary backtracing while trying
609 to find an invalid ID, we check for a common situation where
610 we can detect from comparing stack addresses that no other
611 frame in the current frame chain can have this ID. See the
612 comment at frame_id_inner for details. */
613 if (get_frame_type (frame) == NORMAL_FRAME
614 && !frame_id_inner (get_frame_arch (frame), id, this)
615 && frame_id_inner (get_frame_arch (prev_frame), id,
616 get_frame_id (prev_frame)))
623 frame_unwind_pc_if_available (struct frame_info *this_frame, CORE_ADDR *pc)
625 if (!this_frame->prev_pc.p)
627 if (gdbarch_unwind_pc_p (frame_unwind_arch (this_frame)))
629 volatile struct gdb_exception ex;
630 struct gdbarch *prev_gdbarch;
633 /* The right way. The `pure' way. The one true way. This
634 method depends solely on the register-unwind code to
635 determine the value of registers in THIS frame, and hence
636 the value of this frame's PC (resume address). A typical
637 implementation is no more than:
639 frame_unwind_register (this_frame, ISA_PC_REGNUM, buf);
640 return extract_unsigned_integer (buf, size of ISA_PC_REGNUM);
642 Note: this method is very heavily dependent on a correct
643 register-unwind implementation, it pays to fix that
644 method first; this method is frame type agnostic, since
645 it only deals with register values, it works with any
646 frame. This is all in stark contrast to the old
647 FRAME_SAVED_PC which would try to directly handle all the
648 different ways that a PC could be unwound. */
649 prev_gdbarch = frame_unwind_arch (this_frame);
651 TRY_CATCH (ex, RETURN_MASK_ERROR)
653 pc = gdbarch_unwind_pc (prev_gdbarch, this_frame);
655 if (ex.reason < 0 && ex.error == NOT_AVAILABLE_ERROR)
657 this_frame->prev_pc.p = -1;
660 fprintf_unfiltered (gdb_stdlog,
661 "{ frame_unwind_pc (this_frame=%d)"
662 " -> <unavailable> }\n",
665 else if (ex.reason < 0)
667 throw_exception (ex);
671 this_frame->prev_pc.value = pc;
672 this_frame->prev_pc.p = 1;
674 fprintf_unfiltered (gdb_stdlog,
675 "{ frame_unwind_pc (this_frame=%d) "
678 hex_string (this_frame->prev_pc.value));
682 internal_error (__FILE__, __LINE__, _("No unwind_pc method"));
684 if (this_frame->prev_pc.p < 0)
691 *pc = this_frame->prev_pc.value;
697 frame_unwind_pc (struct frame_info *this_frame)
701 if (!frame_unwind_pc_if_available (this_frame, &pc))
702 throw_error (NOT_AVAILABLE_ERROR, _("PC not available"));
708 frame_unwind_caller_pc (struct frame_info *this_frame)
710 return frame_unwind_pc (skip_inlined_frames (this_frame));
714 frame_unwind_caller_pc_if_available (struct frame_info *this_frame,
717 return frame_unwind_pc_if_available (skip_inlined_frames (this_frame), pc);
721 get_frame_func_if_available (struct frame_info *this_frame, CORE_ADDR *pc)
723 struct frame_info *next_frame = this_frame->next;
725 if (!next_frame->prev_func.p)
727 CORE_ADDR addr_in_block;
729 /* Make certain that this, and not the adjacent, function is
731 if (!get_frame_address_in_block_if_available (this_frame, &addr_in_block))
733 next_frame->prev_func.p = -1;
735 fprintf_unfiltered (gdb_stdlog,
736 "{ get_frame_func (this_frame=%d)"
737 " -> unavailable }\n",
742 next_frame->prev_func.p = 1;
743 next_frame->prev_func.addr = get_pc_function_start (addr_in_block);
745 fprintf_unfiltered (gdb_stdlog,
746 "{ get_frame_func (this_frame=%d) -> %s }\n",
748 hex_string (next_frame->prev_func.addr));
752 if (next_frame->prev_func.p < 0)
759 *pc = next_frame->prev_func.addr;
765 get_frame_func (struct frame_info *this_frame)
769 if (!get_frame_func_if_available (this_frame, &pc))
770 throw_error (NOT_AVAILABLE_ERROR, _("PC not available"));
775 static enum register_status
776 do_frame_register_read (void *src, int regnum, gdb_byte *buf)
778 if (!frame_register_read (src, regnum, buf))
779 return REG_UNAVAILABLE;
785 frame_save_as_regcache (struct frame_info *this_frame)
787 struct address_space *aspace = get_frame_address_space (this_frame);
788 struct regcache *regcache = regcache_xmalloc (get_frame_arch (this_frame),
790 struct cleanup *cleanups = make_cleanup_regcache_xfree (regcache);
792 regcache_save (regcache, do_frame_register_read, this_frame);
793 discard_cleanups (cleanups);
798 frame_pop (struct frame_info *this_frame)
800 struct frame_info *prev_frame;
801 struct regcache *scratch;
802 struct cleanup *cleanups;
804 if (get_frame_type (this_frame) == DUMMY_FRAME)
806 /* Popping a dummy frame involves restoring more than just registers.
807 dummy_frame_pop does all the work. */
808 dummy_frame_pop (get_frame_id (this_frame));
812 /* Ensure that we have a frame to pop to. */
813 prev_frame = get_prev_frame_1 (this_frame);
816 error (_("Cannot pop the initial frame."));
818 /* Make a copy of all the register values unwound from this frame.
819 Save them in a scratch buffer so that there isn't a race between
820 trying to extract the old values from the current regcache while
821 at the same time writing new values into that same cache. */
822 scratch = frame_save_as_regcache (prev_frame);
823 cleanups = make_cleanup_regcache_xfree (scratch);
825 /* FIXME: cagney/2003-03-16: It should be possible to tell the
826 target's register cache that it is about to be hit with a burst
827 register transfer and that the sequence of register writes should
828 be batched. The pair target_prepare_to_store() and
829 target_store_registers() kind of suggest this functionality.
830 Unfortunately, they don't implement it. Their lack of a formal
831 definition can lead to targets writing back bogus values
832 (arguably a bug in the target code mind). */
833 /* Now copy those saved registers into the current regcache.
834 Here, regcache_cpy() calls regcache_restore(). */
835 regcache_cpy (get_current_regcache (), scratch);
836 do_cleanups (cleanups);
838 /* We've made right mess of GDB's local state, just discard
840 reinit_frame_cache ();
844 frame_register_unwind (struct frame_info *frame, int regnum,
845 int *optimizedp, int *unavailablep,
846 enum lval_type *lvalp, CORE_ADDR *addrp,
847 int *realnump, gdb_byte *bufferp)
851 /* Require all but BUFFERP to be valid. A NULL BUFFERP indicates
852 that the value proper does not need to be fetched. */
853 gdb_assert (optimizedp != NULL);
854 gdb_assert (lvalp != NULL);
855 gdb_assert (addrp != NULL);
856 gdb_assert (realnump != NULL);
857 /* gdb_assert (bufferp != NULL); */
859 value = frame_unwind_register_value (frame, regnum);
861 gdb_assert (value != NULL);
863 *optimizedp = value_optimized_out (value);
864 *unavailablep = !value_entirely_available (value);
865 *lvalp = VALUE_LVAL (value);
866 *addrp = value_address (value);
867 *realnump = VALUE_REGNUM (value);
871 if (!*optimizedp && !*unavailablep)
872 memcpy (bufferp, value_contents_all (value),
873 TYPE_LENGTH (value_type (value)));
875 memset (bufferp, 0, TYPE_LENGTH (value_type (value)));
878 /* Dispose of the new value. This prevents watchpoints from
879 trying to watch the saved frame pointer. */
880 release_value (value);
885 frame_register (struct frame_info *frame, int regnum,
886 int *optimizedp, int *unavailablep, enum lval_type *lvalp,
887 CORE_ADDR *addrp, int *realnump, gdb_byte *bufferp)
889 /* Require all but BUFFERP to be valid. A NULL BUFFERP indicates
890 that the value proper does not need to be fetched. */
891 gdb_assert (optimizedp != NULL);
892 gdb_assert (lvalp != NULL);
893 gdb_assert (addrp != NULL);
894 gdb_assert (realnump != NULL);
895 /* gdb_assert (bufferp != NULL); */
897 /* Obtain the register value by unwinding the register from the next
898 (more inner frame). */
899 gdb_assert (frame != NULL && frame->next != NULL);
900 frame_register_unwind (frame->next, regnum, optimizedp, unavailablep,
901 lvalp, addrp, realnump, bufferp);
905 frame_unwind_register (struct frame_info *frame, int regnum, gdb_byte *buf)
913 frame_register_unwind (frame, regnum, &optimized, &unavailable,
914 &lval, &addr, &realnum, buf);
917 error (_("Register %d was optimized out"), regnum);
919 throw_error (NOT_AVAILABLE_ERROR,
920 _("Register %d is not available"), regnum);
924 get_frame_register (struct frame_info *frame,
925 int regnum, gdb_byte *buf)
927 frame_unwind_register (frame->next, regnum, buf);
931 frame_unwind_register_value (struct frame_info *frame, int regnum)
933 struct gdbarch *gdbarch;
936 gdb_assert (frame != NULL);
937 gdbarch = frame_unwind_arch (frame);
941 fprintf_unfiltered (gdb_stdlog,
942 "{ frame_unwind_register_value "
943 "(frame=%d,regnum=%d(%s),...) ",
944 frame->level, regnum,
945 user_reg_map_regnum_to_name (gdbarch, regnum));
948 /* Find the unwinder. */
949 if (frame->unwind == NULL)
950 frame_unwind_find_by_frame (frame, &frame->prologue_cache);
952 /* Ask this frame to unwind its register. */
953 value = frame->unwind->prev_register (frame, &frame->prologue_cache, regnum);
957 fprintf_unfiltered (gdb_stdlog, "->");
958 if (value_optimized_out (value))
959 fprintf_unfiltered (gdb_stdlog, " optimized out");
962 if (VALUE_LVAL (value) == lval_register)
963 fprintf_unfiltered (gdb_stdlog, " register=%d",
964 VALUE_REGNUM (value));
965 else if (VALUE_LVAL (value) == lval_memory)
966 fprintf_unfiltered (gdb_stdlog, " address=%s",
968 value_address (value)));
970 fprintf_unfiltered (gdb_stdlog, " computed");
972 if (value_lazy (value))
973 fprintf_unfiltered (gdb_stdlog, " lazy");
977 const gdb_byte *buf = value_contents (value);
979 fprintf_unfiltered (gdb_stdlog, " bytes=");
980 fprintf_unfiltered (gdb_stdlog, "[");
981 for (i = 0; i < register_size (gdbarch, regnum); i++)
982 fprintf_unfiltered (gdb_stdlog, "%02x", buf[i]);
983 fprintf_unfiltered (gdb_stdlog, "]");
987 fprintf_unfiltered (gdb_stdlog, " }\n");
994 get_frame_register_value (struct frame_info *frame, int regnum)
996 return frame_unwind_register_value (frame->next, regnum);
1000 frame_unwind_register_signed (struct frame_info *frame, int regnum)
1002 struct gdbarch *gdbarch = frame_unwind_arch (frame);
1003 enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
1004 int size = register_size (gdbarch, regnum);
1005 gdb_byte buf[MAX_REGISTER_SIZE];
1007 frame_unwind_register (frame, regnum, buf);
1008 return extract_signed_integer (buf, size, byte_order);
1012 get_frame_register_signed (struct frame_info *frame, int regnum)
1014 return frame_unwind_register_signed (frame->next, regnum);
1018 frame_unwind_register_unsigned (struct frame_info *frame, int regnum)
1020 struct gdbarch *gdbarch = frame_unwind_arch (frame);
1021 enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
1022 int size = register_size (gdbarch, regnum);
1023 gdb_byte buf[MAX_REGISTER_SIZE];
1025 frame_unwind_register (frame, regnum, buf);
1026 return extract_unsigned_integer (buf, size, byte_order);
1030 get_frame_register_unsigned (struct frame_info *frame, int regnum)
1032 return frame_unwind_register_unsigned (frame->next, regnum);
1036 put_frame_register (struct frame_info *frame, int regnum,
1037 const gdb_byte *buf)
1039 struct gdbarch *gdbarch = get_frame_arch (frame);
1043 enum lval_type lval;
1046 frame_register (frame, regnum, &optim, &unavail,
1047 &lval, &addr, &realnum, NULL);
1049 error (_("Attempt to assign to a value that was optimized out."));
1054 /* FIXME: write_memory doesn't yet take constant buffers.
1056 gdb_byte tmp[MAX_REGISTER_SIZE];
1058 memcpy (tmp, buf, register_size (gdbarch, regnum));
1059 write_memory (addr, tmp, register_size (gdbarch, regnum));
1063 regcache_cooked_write (get_current_regcache (), realnum, buf);
1066 error (_("Attempt to assign to an unmodifiable value."));
1070 /* frame_register_read ()
1072 Find and return the value of REGNUM for the specified stack frame.
1073 The number of bytes copied is REGISTER_SIZE (REGNUM).
1075 Returns 0 if the register value could not be found. */
1078 frame_register_read (struct frame_info *frame, int regnum,
1083 enum lval_type lval;
1087 frame_register (frame, regnum, &optimized, &unavailable,
1088 &lval, &addr, &realnum, myaddr);
1090 return !optimized && !unavailable;
1094 get_frame_register_bytes (struct frame_info *frame, int regnum,
1095 CORE_ADDR offset, int len, gdb_byte *myaddr,
1096 int *optimizedp, int *unavailablep)
1098 struct gdbarch *gdbarch = get_frame_arch (frame);
1103 /* Skip registers wholly inside of OFFSET. */
1104 while (offset >= register_size (gdbarch, regnum))
1106 offset -= register_size (gdbarch, regnum);
1110 /* Ensure that we will not read beyond the end of the register file.
1111 This can only ever happen if the debug information is bad. */
1113 numregs = gdbarch_num_regs (gdbarch) + gdbarch_num_pseudo_regs (gdbarch);
1114 for (i = regnum; i < numregs; i++)
1116 int thissize = register_size (gdbarch, i);
1119 break; /* This register is not available on this architecture. */
1120 maxsize += thissize;
1123 error (_("Bad debug information detected: "
1124 "Attempt to read %d bytes from registers."), len);
1126 /* Copy the data. */
1129 int curr_len = register_size (gdbarch, regnum) - offset;
1134 if (curr_len == register_size (gdbarch, regnum))
1136 enum lval_type lval;
1140 frame_register (frame, regnum, optimizedp, unavailablep,
1141 &lval, &addr, &realnum, myaddr);
1142 if (*optimizedp || *unavailablep)
1147 gdb_byte buf[MAX_REGISTER_SIZE];
1148 enum lval_type lval;
1152 frame_register (frame, regnum, optimizedp, unavailablep,
1153 &lval, &addr, &realnum, buf);
1154 if (*optimizedp || *unavailablep)
1156 memcpy (myaddr, buf + offset, curr_len);
1171 put_frame_register_bytes (struct frame_info *frame, int regnum,
1172 CORE_ADDR offset, int len, const gdb_byte *myaddr)
1174 struct gdbarch *gdbarch = get_frame_arch (frame);
1176 /* Skip registers wholly inside of OFFSET. */
1177 while (offset >= register_size (gdbarch, regnum))
1179 offset -= register_size (gdbarch, regnum);
1183 /* Copy the data. */
1186 int curr_len = register_size (gdbarch, regnum) - offset;
1191 if (curr_len == register_size (gdbarch, regnum))
1193 put_frame_register (frame, regnum, myaddr);
1197 gdb_byte buf[MAX_REGISTER_SIZE];
1199 frame_register_read (frame, regnum, buf);
1200 memcpy (buf + offset, myaddr, curr_len);
1201 put_frame_register (frame, regnum, buf);
1211 /* Create a sentinel frame. */
1213 static struct frame_info *
1214 create_sentinel_frame (struct program_space *pspace, struct regcache *regcache)
1216 struct frame_info *frame = FRAME_OBSTACK_ZALLOC (struct frame_info);
1219 frame->pspace = pspace;
1220 frame->aspace = get_regcache_aspace (regcache);
1221 /* Explicitly initialize the sentinel frame's cache. Provide it
1222 with the underlying regcache. In the future additional
1223 information, such as the frame's thread will be added. */
1224 frame->prologue_cache = sentinel_frame_cache (regcache);
1225 /* For the moment there is only one sentinel frame implementation. */
1226 frame->unwind = &sentinel_frame_unwind;
1227 /* Link this frame back to itself. The frame is self referential
1228 (the unwound PC is the same as the pc), so make it so. */
1229 frame->next = frame;
1230 /* Make the sentinel frame's ID valid, but invalid. That way all
1231 comparisons with it should fail. */
1232 frame->this_id.p = 1;
1233 frame->this_id.value = null_frame_id;
1236 fprintf_unfiltered (gdb_stdlog, "{ create_sentinel_frame (...) -> ");
1237 fprint_frame (gdb_stdlog, frame);
1238 fprintf_unfiltered (gdb_stdlog, " }\n");
1243 /* Info about the innermost stack frame (contents of FP register). */
1245 static struct frame_info *current_frame;
1247 /* Cache for frame addresses already read by gdb. Valid only while
1248 inferior is stopped. Control variables for the frame cache should
1249 be local to this module. */
1251 static struct obstack frame_cache_obstack;
1254 frame_obstack_zalloc (unsigned long size)
1256 void *data = obstack_alloc (&frame_cache_obstack, size);
1258 memset (data, 0, size);
1262 /* Return the innermost (currently executing) stack frame. This is
1263 split into two functions. The function unwind_to_current_frame()
1264 is wrapped in catch exceptions so that, even when the unwind of the
1265 sentinel frame fails, the function still returns a stack frame. */
1268 unwind_to_current_frame (struct ui_out *ui_out, void *args)
1270 struct frame_info *frame = get_prev_frame (args);
1272 /* A sentinel frame can fail to unwind, e.g., because its PC value
1273 lands in somewhere like start. */
1276 current_frame = frame;
1281 get_current_frame (void)
1283 /* First check, and report, the lack of registers. Having GDB
1284 report "No stack!" or "No memory" when the target doesn't even
1285 have registers is very confusing. Besides, "printcmd.exp"
1286 explicitly checks that ``print $pc'' with no registers prints "No
1288 if (!target_has_registers)
1289 error (_("No registers."));
1290 if (!target_has_stack)
1291 error (_("No stack."));
1292 if (!target_has_memory)
1293 error (_("No memory."));
1294 /* Traceframes are effectively a substitute for the live inferior. */
1295 if (get_traceframe_number () < 0)
1297 if (ptid_equal (inferior_ptid, null_ptid))
1298 error (_("No selected thread."));
1299 if (is_exited (inferior_ptid))
1300 error (_("Invalid selected thread."));
1301 if (is_executing (inferior_ptid))
1302 error (_("Target is executing."));
1305 if (current_frame == NULL)
1307 struct frame_info *sentinel_frame =
1308 create_sentinel_frame (current_program_space, get_current_regcache ());
1309 if (catch_exceptions (uiout, unwind_to_current_frame, sentinel_frame,
1310 RETURN_MASK_ERROR) != 0)
1312 /* Oops! Fake a current frame? Is this useful? It has a PC
1313 of zero, for instance. */
1314 current_frame = sentinel_frame;
1317 return current_frame;
1320 /* The "selected" stack frame is used by default for local and arg
1321 access. May be zero, for no selected frame. */
1323 static struct frame_info *selected_frame;
1326 has_stack_frames (void)
1328 if (!target_has_registers || !target_has_stack || !target_has_memory)
1331 /* No current inferior, no frame. */
1332 if (ptid_equal (inferior_ptid, null_ptid))
1335 /* Don't try to read from a dead thread. */
1336 if (is_exited (inferior_ptid))
1339 /* ... or from a spinning thread. */
1340 if (is_executing (inferior_ptid))
1346 /* Return the selected frame. Always non-NULL (unless there isn't an
1347 inferior sufficient for creating a frame) in which case an error is
1351 get_selected_frame (const char *message)
1353 if (selected_frame == NULL)
1355 if (message != NULL && !has_stack_frames ())
1356 error (("%s"), message);
1357 /* Hey! Don't trust this. It should really be re-finding the
1358 last selected frame of the currently selected thread. This,
1359 though, is better than nothing. */
1360 select_frame (get_current_frame ());
1362 /* There is always a frame. */
1363 gdb_assert (selected_frame != NULL);
1364 return selected_frame;
1367 /* If there is a selected frame, return it. Otherwise, return NULL. */
1370 get_selected_frame_if_set (void)
1372 return selected_frame;
1375 /* This is a variant of get_selected_frame() which can be called when
1376 the inferior does not have a frame; in that case it will return
1377 NULL instead of calling error(). */
1380 deprecated_safe_get_selected_frame (void)
1382 if (!has_stack_frames ())
1384 return get_selected_frame (NULL);
1387 /* Select frame FI (or NULL - to invalidate the current frame). */
1390 select_frame (struct frame_info *fi)
1392 selected_frame = fi;
1393 /* NOTE: cagney/2002-05-04: FI can be NULL. This occurs when the
1394 frame is being invalidated. */
1395 if (deprecated_selected_frame_level_changed_hook)
1396 deprecated_selected_frame_level_changed_hook (frame_relative_level (fi));
1398 /* FIXME: kseitz/2002-08-28: It would be nice to call
1399 selected_frame_level_changed_event() right here, but due to limitations
1400 in the current interfaces, we would end up flooding UIs with events
1401 because select_frame() is used extensively internally.
1403 Once we have frame-parameterized frame (and frame-related) commands,
1404 the event notification can be moved here, since this function will only
1405 be called when the user's selected frame is being changed. */
1407 /* Ensure that symbols for this frame are read in. Also, determine the
1408 source language of this frame, and switch to it if desired. */
1413 /* We retrieve the frame's symtab by using the frame PC.
1414 However we cannot use the frame PC as-is, because it usually
1415 points to the instruction following the "call", which is
1416 sometimes the first instruction of another function. So we
1417 rely on get_frame_address_in_block() which provides us with a
1418 PC which is guaranteed to be inside the frame's code
1420 if (get_frame_address_in_block_if_available (fi, &pc))
1422 struct symtab *s = find_pc_symtab (pc);
1425 && s->language != current_language->la_language
1426 && s->language != language_unknown
1427 && language_mode == language_mode_auto)
1428 set_language (s->language);
1433 /* Create an arbitrary (i.e. address specified by user) or innermost frame.
1434 Always returns a non-NULL value. */
1437 create_new_frame (CORE_ADDR addr, CORE_ADDR pc)
1439 struct frame_info *fi;
1443 fprintf_unfiltered (gdb_stdlog,
1444 "{ create_new_frame (addr=%s, pc=%s) ",
1445 hex_string (addr), hex_string (pc));
1448 fi = FRAME_OBSTACK_ZALLOC (struct frame_info);
1450 fi->next = create_sentinel_frame (current_program_space,
1451 get_current_regcache ());
1453 /* Set/update this frame's cached PC value, found in the next frame.
1454 Do this before looking for this frame's unwinder. A sniffer is
1455 very likely to read this, and the corresponding unwinder is
1456 entitled to rely that the PC doesn't magically change. */
1457 fi->next->prev_pc.value = pc;
1458 fi->next->prev_pc.p = 1;
1460 /* We currently assume that frame chain's can't cross spaces. */
1461 fi->pspace = fi->next->pspace;
1462 fi->aspace = fi->next->aspace;
1464 /* Select/initialize both the unwind function and the frame's type
1466 frame_unwind_find_by_frame (fi, &fi->prologue_cache);
1469 fi->this_id.value = frame_id_build (addr, pc);
1473 fprintf_unfiltered (gdb_stdlog, "-> ");
1474 fprint_frame (gdb_stdlog, fi);
1475 fprintf_unfiltered (gdb_stdlog, " }\n");
1481 /* Return the frame that THIS_FRAME calls (NULL if THIS_FRAME is the
1482 innermost frame). Be careful to not fall off the bottom of the
1483 frame chain and onto the sentinel frame. */
1486 get_next_frame (struct frame_info *this_frame)
1488 if (this_frame->level > 0)
1489 return this_frame->next;
1494 /* Observer for the target_changed event. */
1497 frame_observer_target_changed (struct target_ops *target)
1499 reinit_frame_cache ();
1502 /* Flush the entire frame cache. */
1505 reinit_frame_cache (void)
1507 struct frame_info *fi;
1509 /* Tear down all frame caches. */
1510 for (fi = current_frame; fi != NULL; fi = fi->prev)
1512 if (fi->prologue_cache && fi->unwind->dealloc_cache)
1513 fi->unwind->dealloc_cache (fi, fi->prologue_cache);
1514 if (fi->base_cache && fi->base->unwind->dealloc_cache)
1515 fi->base->unwind->dealloc_cache (fi, fi->base_cache);
1518 /* Since we can't really be sure what the first object allocated was. */
1519 obstack_free (&frame_cache_obstack, 0);
1520 obstack_init (&frame_cache_obstack);
1522 if (current_frame != NULL)
1523 annotate_frames_invalid ();
1525 current_frame = NULL; /* Invalidate cache */
1526 select_frame (NULL);
1527 frame_stash_invalidate ();
1529 fprintf_unfiltered (gdb_stdlog, "{ reinit_frame_cache () }\n");
1532 /* Find where a register is saved (in memory or another register).
1533 The result of frame_register_unwind is just where it is saved
1534 relative to this particular frame. */
1537 frame_register_unwind_location (struct frame_info *this_frame, int regnum,
1538 int *optimizedp, enum lval_type *lvalp,
1539 CORE_ADDR *addrp, int *realnump)
1541 gdb_assert (this_frame == NULL || this_frame->level >= 0);
1543 while (this_frame != NULL)
1547 frame_register_unwind (this_frame, regnum, optimizedp, &unavailable,
1548 lvalp, addrp, realnump, NULL);
1553 if (*lvalp != lval_register)
1557 this_frame = get_next_frame (this_frame);
1561 /* Return a "struct frame_info" corresponding to the frame that called
1562 THIS_FRAME. Returns NULL if there is no such frame.
1564 Unlike get_prev_frame, this function always tries to unwind the
1567 static struct frame_info *
1568 get_prev_frame_1 (struct frame_info *this_frame)
1570 struct frame_id this_id;
1571 struct gdbarch *gdbarch;
1573 gdb_assert (this_frame != NULL);
1574 gdbarch = get_frame_arch (this_frame);
1578 fprintf_unfiltered (gdb_stdlog, "{ get_prev_frame_1 (this_frame=");
1579 if (this_frame != NULL)
1580 fprintf_unfiltered (gdb_stdlog, "%d", this_frame->level);
1582 fprintf_unfiltered (gdb_stdlog, "<NULL>");
1583 fprintf_unfiltered (gdb_stdlog, ") ");
1586 /* Only try to do the unwind once. */
1587 if (this_frame->prev_p)
1591 fprintf_unfiltered (gdb_stdlog, "-> ");
1592 fprint_frame (gdb_stdlog, this_frame->prev);
1593 fprintf_unfiltered (gdb_stdlog, " // cached \n");
1595 return this_frame->prev;
1598 /* If the frame unwinder hasn't been selected yet, we must do so
1599 before setting prev_p; otherwise the check for misbehaved
1600 sniffers will think that this frame's sniffer tried to unwind
1601 further (see frame_cleanup_after_sniffer). */
1602 if (this_frame->unwind == NULL)
1603 frame_unwind_find_by_frame (this_frame, &this_frame->prologue_cache);
1605 this_frame->prev_p = 1;
1606 this_frame->stop_reason = UNWIND_NO_REASON;
1608 /* If we are unwinding from an inline frame, all of the below tests
1609 were already performed when we unwound from the next non-inline
1610 frame. We must skip them, since we can not get THIS_FRAME's ID
1611 until we have unwound all the way down to the previous non-inline
1613 if (get_frame_type (this_frame) == INLINE_FRAME)
1614 return get_prev_frame_raw (this_frame);
1616 /* Check that this frame is unwindable. If it isn't, don't try to
1617 unwind to the prev frame. */
1618 this_frame->stop_reason
1619 = this_frame->unwind->stop_reason (this_frame,
1620 &this_frame->prologue_cache);
1622 if (this_frame->stop_reason != UNWIND_NO_REASON)
1625 /* Check that this frame's ID was valid. If it wasn't, don't try to
1626 unwind to the prev frame. Be careful to not apply this test to
1627 the sentinel frame. */
1628 this_id = get_frame_id (this_frame);
1629 if (this_frame->level >= 0 && frame_id_eq (this_id, outer_frame_id))
1633 fprintf_unfiltered (gdb_stdlog, "-> ");
1634 fprint_frame (gdb_stdlog, NULL);
1635 fprintf_unfiltered (gdb_stdlog, " // this ID is NULL }\n");
1637 this_frame->stop_reason = UNWIND_NULL_ID;
1641 /* Check that this frame's ID isn't inner to (younger, below, next)
1642 the next frame. This happens when a frame unwind goes backwards.
1643 This check is valid only if this frame and the next frame are NORMAL.
1644 See the comment at frame_id_inner for details. */
1645 if (get_frame_type (this_frame) == NORMAL_FRAME
1646 && this_frame->next->unwind->type == NORMAL_FRAME
1647 && frame_id_inner (get_frame_arch (this_frame->next), this_id,
1648 get_frame_id (this_frame->next)))
1650 CORE_ADDR this_pc_in_block;
1651 struct minimal_symbol *morestack_msym;
1652 const char *morestack_name = NULL;
1654 /* gcc -fsplit-stack __morestack can continue the stack anywhere. */
1655 this_pc_in_block = get_frame_address_in_block (this_frame);
1656 morestack_msym = lookup_minimal_symbol_by_pc (this_pc_in_block);
1658 morestack_name = SYMBOL_LINKAGE_NAME (morestack_msym);
1659 if (!morestack_name || strcmp (morestack_name, "__morestack") != 0)
1663 fprintf_unfiltered (gdb_stdlog, "-> ");
1664 fprint_frame (gdb_stdlog, NULL);
1665 fprintf_unfiltered (gdb_stdlog,
1666 " // this frame ID is inner }\n");
1668 this_frame->stop_reason = UNWIND_INNER_ID;
1673 /* Check that this and the next frame are not identical. If they
1674 are, there is most likely a stack cycle. As with the inner-than
1675 test above, avoid comparing the inner-most and sentinel frames. */
1676 if (this_frame->level > 0
1677 && frame_id_eq (this_id, get_frame_id (this_frame->next)))
1681 fprintf_unfiltered (gdb_stdlog, "-> ");
1682 fprint_frame (gdb_stdlog, NULL);
1683 fprintf_unfiltered (gdb_stdlog, " // this frame has same ID }\n");
1685 this_frame->stop_reason = UNWIND_SAME_ID;
1689 /* Check that this and the next frame do not unwind the PC register
1690 to the same memory location. If they do, then even though they
1691 have different frame IDs, the new frame will be bogus; two
1692 functions can't share a register save slot for the PC. This can
1693 happen when the prologue analyzer finds a stack adjustment, but
1696 This check does assume that the "PC register" is roughly a
1697 traditional PC, even if the gdbarch_unwind_pc method adjusts
1698 it (we do not rely on the value, only on the unwound PC being
1699 dependent on this value). A potential improvement would be
1700 to have the frame prev_pc method and the gdbarch unwind_pc
1701 method set the same lval and location information as
1702 frame_register_unwind. */
1703 if (this_frame->level > 0
1704 && gdbarch_pc_regnum (gdbarch) >= 0
1705 && get_frame_type (this_frame) == NORMAL_FRAME
1706 && (get_frame_type (this_frame->next) == NORMAL_FRAME
1707 || get_frame_type (this_frame->next) == INLINE_FRAME))
1709 int optimized, realnum, nrealnum;
1710 enum lval_type lval, nlval;
1711 CORE_ADDR addr, naddr;
1713 frame_register_unwind_location (this_frame,
1714 gdbarch_pc_regnum (gdbarch),
1715 &optimized, &lval, &addr, &realnum);
1716 frame_register_unwind_location (get_next_frame (this_frame),
1717 gdbarch_pc_regnum (gdbarch),
1718 &optimized, &nlval, &naddr, &nrealnum);
1720 if ((lval == lval_memory && lval == nlval && addr == naddr)
1721 || (lval == lval_register && lval == nlval && realnum == nrealnum))
1725 fprintf_unfiltered (gdb_stdlog, "-> ");
1726 fprint_frame (gdb_stdlog, NULL);
1727 fprintf_unfiltered (gdb_stdlog, " // no saved PC }\n");
1730 this_frame->stop_reason = UNWIND_NO_SAVED_PC;
1731 this_frame->prev = NULL;
1736 return get_prev_frame_raw (this_frame);
1739 /* Construct a new "struct frame_info" and link it previous to
1742 static struct frame_info *
1743 get_prev_frame_raw (struct frame_info *this_frame)
1745 struct frame_info *prev_frame;
1747 /* Allocate the new frame but do not wire it in to the frame chain.
1748 Some (bad) code in INIT_FRAME_EXTRA_INFO tries to look along
1749 frame->next to pull some fancy tricks (of course such code is, by
1750 definition, recursive). Try to prevent it.
1752 There is no reason to worry about memory leaks, should the
1753 remainder of the function fail. The allocated memory will be
1754 quickly reclaimed when the frame cache is flushed, and the `we've
1755 been here before' check above will stop repeated memory
1756 allocation calls. */
1757 prev_frame = FRAME_OBSTACK_ZALLOC (struct frame_info);
1758 prev_frame->level = this_frame->level + 1;
1760 /* For now, assume we don't have frame chains crossing address
1762 prev_frame->pspace = this_frame->pspace;
1763 prev_frame->aspace = this_frame->aspace;
1765 /* Don't yet compute ->unwind (and hence ->type). It is computed
1766 on-demand in get_frame_type, frame_register_unwind, and
1769 /* Don't yet compute the frame's ID. It is computed on-demand by
1772 /* The unwound frame ID is validate at the start of this function,
1773 as part of the logic to decide if that frame should be further
1774 unwound, and not here while the prev frame is being created.
1775 Doing this makes it possible for the user to examine a frame that
1776 has an invalid frame ID.
1778 Some very old VAX code noted: [...] For the sake of argument,
1779 suppose that the stack is somewhat trashed (which is one reason
1780 that "info frame" exists). So, return 0 (indicating we don't
1781 know the address of the arglist) if we don't know what frame this
1785 this_frame->prev = prev_frame;
1786 prev_frame->next = this_frame;
1790 fprintf_unfiltered (gdb_stdlog, "-> ");
1791 fprint_frame (gdb_stdlog, prev_frame);
1792 fprintf_unfiltered (gdb_stdlog, " }\n");
1798 /* Debug routine to print a NULL frame being returned. */
1801 frame_debug_got_null_frame (struct frame_info *this_frame,
1806 fprintf_unfiltered (gdb_stdlog, "{ get_prev_frame (this_frame=");
1807 if (this_frame != NULL)
1808 fprintf_unfiltered (gdb_stdlog, "%d", this_frame->level);
1810 fprintf_unfiltered (gdb_stdlog, "<NULL>");
1811 fprintf_unfiltered (gdb_stdlog, ") -> // %s}\n", reason);
1815 /* Is this (non-sentinel) frame in the "main"() function? */
1818 inside_main_func (struct frame_info *this_frame)
1820 struct minimal_symbol *msymbol;
1823 if (symfile_objfile == 0)
1825 msymbol = lookup_minimal_symbol (main_name (), NULL, symfile_objfile);
1826 if (msymbol == NULL)
1828 /* Make certain that the code, and not descriptor, address is
1830 maddr = gdbarch_convert_from_func_ptr_addr (get_frame_arch (this_frame),
1831 SYMBOL_VALUE_ADDRESS (msymbol),
1833 return maddr == get_frame_func (this_frame);
1836 /* Test whether THIS_FRAME is inside the process entry point function. */
1839 inside_entry_func (struct frame_info *this_frame)
1841 CORE_ADDR entry_point;
1843 if (!entry_point_address_query (&entry_point))
1846 return get_frame_func (this_frame) == entry_point;
1849 /* Return a structure containing various interesting information about
1850 the frame that called THIS_FRAME. Returns NULL if there is entier
1851 no such frame or the frame fails any of a set of target-independent
1852 condition that should terminate the frame chain (e.g., as unwinding
1855 This function should not contain target-dependent tests, such as
1856 checking whether the program-counter is zero. */
1859 get_prev_frame (struct frame_info *this_frame)
1864 /* There is always a frame. If this assertion fails, suspect that
1865 something should be calling get_selected_frame() or
1866 get_current_frame(). */
1867 gdb_assert (this_frame != NULL);
1868 frame_pc_p = get_frame_pc_if_available (this_frame, &frame_pc);
1870 /* tausq/2004-12-07: Dummy frames are skipped because it doesn't make much
1871 sense to stop unwinding at a dummy frame. One place where a dummy
1872 frame may have an address "inside_main_func" is on HPUX. On HPUX, the
1873 pcsqh register (space register for the instruction at the head of the
1874 instruction queue) cannot be written directly; the only way to set it
1875 is to branch to code that is in the target space. In order to implement
1876 frame dummies on HPUX, the called function is made to jump back to where
1877 the inferior was when the user function was called. If gdb was inside
1878 the main function when we created the dummy frame, the dummy frame will
1879 point inside the main function. */
1880 if (this_frame->level >= 0
1881 && get_frame_type (this_frame) == NORMAL_FRAME
1882 && !backtrace_past_main
1884 && inside_main_func (this_frame))
1885 /* Don't unwind past main(). Note, this is done _before_ the
1886 frame has been marked as previously unwound. That way if the
1887 user later decides to enable unwinds past main(), that will
1888 automatically happen. */
1890 frame_debug_got_null_frame (this_frame, "inside main func");
1894 /* If the user's backtrace limit has been exceeded, stop. We must
1895 add two to the current level; one of those accounts for backtrace_limit
1896 being 1-based and the level being 0-based, and the other accounts for
1897 the level of the new frame instead of the level of the current
1899 if (this_frame->level + 2 > backtrace_limit)
1901 frame_debug_got_null_frame (this_frame, "backtrace limit exceeded");
1905 /* If we're already inside the entry function for the main objfile,
1906 then it isn't valid. Don't apply this test to a dummy frame -
1907 dummy frame PCs typically land in the entry func. Don't apply
1908 this test to the sentinel frame. Sentinel frames should always
1909 be allowed to unwind. */
1910 /* NOTE: cagney/2003-07-07: Fixed a bug in inside_main_func() -
1911 wasn't checking for "main" in the minimal symbols. With that
1912 fixed asm-source tests now stop in "main" instead of halting the
1913 backtrace in weird and wonderful ways somewhere inside the entry
1914 file. Suspect that tests for inside the entry file/func were
1915 added to work around that (now fixed) case. */
1916 /* NOTE: cagney/2003-07-15: danielj (if I'm reading it right)
1917 suggested having the inside_entry_func test use the
1918 inside_main_func() msymbol trick (along with entry_point_address()
1919 I guess) to determine the address range of the start function.
1920 That should provide a far better stopper than the current
1922 /* NOTE: tausq/2004-10-09: this is needed if, for example, the compiler
1923 applied tail-call optimizations to main so that a function called
1924 from main returns directly to the caller of main. Since we don't
1925 stop at main, we should at least stop at the entry point of the
1927 if (this_frame->level >= 0
1928 && get_frame_type (this_frame) == NORMAL_FRAME
1929 && !backtrace_past_entry
1931 && inside_entry_func (this_frame))
1933 frame_debug_got_null_frame (this_frame, "inside entry func");
1937 /* Assume that the only way to get a zero PC is through something
1938 like a SIGSEGV or a dummy frame, and hence that NORMAL frames
1939 will never unwind a zero PC. */
1940 if (this_frame->level > 0
1941 && (get_frame_type (this_frame) == NORMAL_FRAME
1942 || get_frame_type (this_frame) == INLINE_FRAME)
1943 && get_frame_type (get_next_frame (this_frame)) == NORMAL_FRAME
1944 && frame_pc_p && frame_pc == 0)
1946 frame_debug_got_null_frame (this_frame, "zero PC");
1950 return get_prev_frame_1 (this_frame);
1954 get_frame_pc (struct frame_info *frame)
1956 gdb_assert (frame->next != NULL);
1957 return frame_unwind_pc (frame->next);
1961 get_frame_pc_if_available (struct frame_info *frame, CORE_ADDR *pc)
1963 volatile struct gdb_exception ex;
1965 gdb_assert (frame->next != NULL);
1967 TRY_CATCH (ex, RETURN_MASK_ERROR)
1969 *pc = frame_unwind_pc (frame->next);
1973 if (ex.error == NOT_AVAILABLE_ERROR)
1976 throw_exception (ex);
1982 /* Return an address that falls within THIS_FRAME's code block. */
1985 get_frame_address_in_block (struct frame_info *this_frame)
1987 /* A draft address. */
1988 CORE_ADDR pc = get_frame_pc (this_frame);
1990 struct frame_info *next_frame = this_frame->next;
1992 /* Calling get_frame_pc returns the resume address for THIS_FRAME.
1993 Normally the resume address is inside the body of the function
1994 associated with THIS_FRAME, but there is a special case: when
1995 calling a function which the compiler knows will never return
1996 (for instance abort), the call may be the very last instruction
1997 in the calling function. The resume address will point after the
1998 call and may be at the beginning of a different function
2001 If THIS_FRAME is a signal frame or dummy frame, then we should
2002 not adjust the unwound PC. For a dummy frame, GDB pushed the
2003 resume address manually onto the stack. For a signal frame, the
2004 OS may have pushed the resume address manually and invoked the
2005 handler (e.g. GNU/Linux), or invoked the trampoline which called
2006 the signal handler - but in either case the signal handler is
2007 expected to return to the trampoline. So in both of these
2008 cases we know that the resume address is executable and
2009 related. So we only need to adjust the PC if THIS_FRAME
2010 is a normal function.
2012 If the program has been interrupted while THIS_FRAME is current,
2013 then clearly the resume address is inside the associated
2014 function. There are three kinds of interruption: debugger stop
2015 (next frame will be SENTINEL_FRAME), operating system
2016 signal or exception (next frame will be SIGTRAMP_FRAME),
2017 or debugger-induced function call (next frame will be
2018 DUMMY_FRAME). So we only need to adjust the PC if
2019 NEXT_FRAME is a normal function.
2021 We check the type of NEXT_FRAME first, since it is already
2022 known; frame type is determined by the unwinder, and since
2023 we have THIS_FRAME we've already selected an unwinder for
2026 If the next frame is inlined, we need to keep going until we find
2027 the real function - for instance, if a signal handler is invoked
2028 while in an inlined function, then the code address of the
2029 "calling" normal function should not be adjusted either. */
2031 while (get_frame_type (next_frame) == INLINE_FRAME)
2032 next_frame = next_frame->next;
2034 if (get_frame_type (next_frame) == NORMAL_FRAME
2035 && (get_frame_type (this_frame) == NORMAL_FRAME
2036 || get_frame_type (this_frame) == INLINE_FRAME))
2043 get_frame_address_in_block_if_available (struct frame_info *this_frame,
2046 volatile struct gdb_exception ex;
2048 TRY_CATCH (ex, RETURN_MASK_ERROR)
2050 *pc = get_frame_address_in_block (this_frame);
2052 if (ex.reason < 0 && ex.error == NOT_AVAILABLE_ERROR)
2054 else if (ex.reason < 0)
2055 throw_exception (ex);
2061 find_frame_sal (struct frame_info *frame, struct symtab_and_line *sal)
2063 struct frame_info *next_frame;
2067 /* If the next frame represents an inlined function call, this frame's
2068 sal is the "call site" of that inlined function, which can not
2069 be inferred from get_frame_pc. */
2070 next_frame = get_next_frame (frame);
2071 if (frame_inlined_callees (frame) > 0)
2076 sym = get_frame_function (next_frame);
2078 sym = inline_skipped_symbol (inferior_ptid);
2080 /* If frame is inline, it certainly has symbols. */
2083 if (SYMBOL_LINE (sym) != 0)
2085 sal->symtab = SYMBOL_SYMTAB (sym);
2086 sal->line = SYMBOL_LINE (sym);
2089 /* If the symbol does not have a location, we don't know where
2090 the call site is. Do not pretend to. This is jarring, but
2091 we can't do much better. */
2092 sal->pc = get_frame_pc (frame);
2097 /* If FRAME is not the innermost frame, that normally means that
2098 FRAME->pc points at the return instruction (which is *after* the
2099 call instruction), and we want to get the line containing the
2100 call (because the call is where the user thinks the program is).
2101 However, if the next frame is either a SIGTRAMP_FRAME or a
2102 DUMMY_FRAME, then the next frame will contain a saved interrupt
2103 PC and such a PC indicates the current (rather than next)
2104 instruction/line, consequently, for such cases, want to get the
2105 line containing fi->pc. */
2106 if (!get_frame_pc_if_available (frame, &pc))
2112 notcurrent = (pc != get_frame_address_in_block (frame));
2113 (*sal) = find_pc_line (pc, notcurrent);
2116 /* Per "frame.h", return the ``address'' of the frame. Code should
2117 really be using get_frame_id(). */
2119 get_frame_base (struct frame_info *fi)
2121 return get_frame_id (fi).stack_addr;
2124 /* High-level offsets into the frame. Used by the debug info. */
2127 get_frame_base_address (struct frame_info *fi)
2129 if (get_frame_type (fi) != NORMAL_FRAME)
2131 if (fi->base == NULL)
2132 fi->base = frame_base_find_by_frame (fi);
2133 /* Sneaky: If the low-level unwind and high-level base code share a
2134 common unwinder, let them share the prologue cache. */
2135 if (fi->base->unwind == fi->unwind)
2136 return fi->base->this_base (fi, &fi->prologue_cache);
2137 return fi->base->this_base (fi, &fi->base_cache);
2141 get_frame_locals_address (struct frame_info *fi)
2143 if (get_frame_type (fi) != NORMAL_FRAME)
2145 /* If there isn't a frame address method, find it. */
2146 if (fi->base == NULL)
2147 fi->base = frame_base_find_by_frame (fi);
2148 /* Sneaky: If the low-level unwind and high-level base code share a
2149 common unwinder, let them share the prologue cache. */
2150 if (fi->base->unwind == fi->unwind)
2151 return fi->base->this_locals (fi, &fi->prologue_cache);
2152 return fi->base->this_locals (fi, &fi->base_cache);
2156 get_frame_args_address (struct frame_info *fi)
2158 if (get_frame_type (fi) != NORMAL_FRAME)
2160 /* If there isn't a frame address method, find it. */
2161 if (fi->base == NULL)
2162 fi->base = frame_base_find_by_frame (fi);
2163 /* Sneaky: If the low-level unwind and high-level base code share a
2164 common unwinder, let them share the prologue cache. */
2165 if (fi->base->unwind == fi->unwind)
2166 return fi->base->this_args (fi, &fi->prologue_cache);
2167 return fi->base->this_args (fi, &fi->base_cache);
2170 /* Return true if the frame unwinder for frame FI is UNWINDER; false
2174 frame_unwinder_is (struct frame_info *fi, const struct frame_unwind *unwinder)
2176 if (fi->unwind == NULL)
2177 frame_unwind_find_by_frame (fi, &fi->prologue_cache);
2178 return fi->unwind == unwinder;
2181 /* Level of the selected frame: 0 for innermost, 1 for its caller, ...
2182 or -1 for a NULL frame. */
2185 frame_relative_level (struct frame_info *fi)
2194 get_frame_type (struct frame_info *frame)
2196 if (frame->unwind == NULL)
2197 /* Initialize the frame's unwinder because that's what
2198 provides the frame's type. */
2199 frame_unwind_find_by_frame (frame, &frame->prologue_cache);
2200 return frame->unwind->type;
2203 struct program_space *
2204 get_frame_program_space (struct frame_info *frame)
2206 return frame->pspace;
2209 struct program_space *
2210 frame_unwind_program_space (struct frame_info *this_frame)
2212 gdb_assert (this_frame);
2214 /* This is really a placeholder to keep the API consistent --- we
2215 assume for now that we don't have frame chains crossing
2217 return this_frame->pspace;
2220 struct address_space *
2221 get_frame_address_space (struct frame_info *frame)
2223 return frame->aspace;
2226 /* Memory access methods. */
2229 get_frame_memory (struct frame_info *this_frame, CORE_ADDR addr,
2230 gdb_byte *buf, int len)
2232 read_memory (addr, buf, len);
2236 get_frame_memory_signed (struct frame_info *this_frame, CORE_ADDR addr,
2239 struct gdbarch *gdbarch = get_frame_arch (this_frame);
2240 enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
2242 return read_memory_integer (addr, len, byte_order);
2246 get_frame_memory_unsigned (struct frame_info *this_frame, CORE_ADDR addr,
2249 struct gdbarch *gdbarch = get_frame_arch (this_frame);
2250 enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
2252 return read_memory_unsigned_integer (addr, len, byte_order);
2256 safe_frame_unwind_memory (struct frame_info *this_frame,
2257 CORE_ADDR addr, gdb_byte *buf, int len)
2259 /* NOTE: target_read_memory returns zero on success! */
2260 return !target_read_memory (addr, buf, len);
2263 /* Architecture methods. */
2266 get_frame_arch (struct frame_info *this_frame)
2268 return frame_unwind_arch (this_frame->next);
2272 frame_unwind_arch (struct frame_info *next_frame)
2274 if (!next_frame->prev_arch.p)
2276 struct gdbarch *arch;
2278 if (next_frame->unwind == NULL)
2279 frame_unwind_find_by_frame (next_frame, &next_frame->prologue_cache);
2281 if (next_frame->unwind->prev_arch != NULL)
2282 arch = next_frame->unwind->prev_arch (next_frame,
2283 &next_frame->prologue_cache);
2285 arch = get_frame_arch (next_frame);
2287 next_frame->prev_arch.arch = arch;
2288 next_frame->prev_arch.p = 1;
2290 fprintf_unfiltered (gdb_stdlog,
2291 "{ frame_unwind_arch (next_frame=%d) -> %s }\n",
2293 gdbarch_bfd_arch_info (arch)->printable_name);
2296 return next_frame->prev_arch.arch;
2300 frame_unwind_caller_arch (struct frame_info *next_frame)
2302 return frame_unwind_arch (skip_inlined_frames (next_frame));
2305 /* Stack pointer methods. */
2308 get_frame_sp (struct frame_info *this_frame)
2310 struct gdbarch *gdbarch = get_frame_arch (this_frame);
2312 /* Normality - an architecture that provides a way of obtaining any
2313 frame inner-most address. */
2314 if (gdbarch_unwind_sp_p (gdbarch))
2315 /* NOTE drow/2008-06-28: gdbarch_unwind_sp could be converted to
2316 operate on THIS_FRAME now. */
2317 return gdbarch_unwind_sp (gdbarch, this_frame->next);
2318 /* Now things are really are grim. Hope that the value returned by
2319 the gdbarch_sp_regnum register is meaningful. */
2320 if (gdbarch_sp_regnum (gdbarch) >= 0)
2321 return get_frame_register_unsigned (this_frame,
2322 gdbarch_sp_regnum (gdbarch));
2323 internal_error (__FILE__, __LINE__, _("Missing unwind SP method"));
2326 /* Return the reason why we can't unwind past FRAME. */
2328 enum unwind_stop_reason
2329 get_frame_unwind_stop_reason (struct frame_info *frame)
2331 /* If we haven't tried to unwind past this point yet, then assume
2332 that unwinding would succeed. */
2333 if (frame->prev_p == 0)
2334 return UNWIND_NO_REASON;
2336 /* Otherwise, we set a reason when we succeeded (or failed) to
2338 return frame->stop_reason;
2341 /* Return a string explaining REASON. */
2344 frame_stop_reason_string (enum unwind_stop_reason reason)
2348 case UNWIND_NULL_ID:
2349 return _("unwinder did not report frame ID");
2351 case UNWIND_UNAVAILABLE:
2352 return _("Not enough registers or memory available to unwind further");
2354 case UNWIND_INNER_ID:
2355 return _("previous frame inner to this frame (corrupt stack?)");
2357 case UNWIND_SAME_ID:
2358 return _("previous frame identical to this frame (corrupt stack?)");
2360 case UNWIND_NO_SAVED_PC:
2361 return _("frame did not save the PC");
2363 case UNWIND_NO_REASON:
2364 case UNWIND_FIRST_ERROR:
2366 internal_error (__FILE__, __LINE__,
2367 "Invalid frame stop reason");
2371 /* Clean up after a failed (wrong unwinder) attempt to unwind past
2375 frame_cleanup_after_sniffer (void *arg)
2377 struct frame_info *frame = arg;
2379 /* The sniffer should not allocate a prologue cache if it did not
2380 match this frame. */
2381 gdb_assert (frame->prologue_cache == NULL);
2383 /* No sniffer should extend the frame chain; sniff based on what is
2385 gdb_assert (!frame->prev_p);
2387 /* The sniffer should not check the frame's ID; that's circular. */
2388 gdb_assert (!frame->this_id.p);
2390 /* Clear cached fields dependent on the unwinder.
2392 The previous PC is independent of the unwinder, but the previous
2393 function is not (see get_frame_address_in_block). */
2394 frame->prev_func.p = 0;
2395 frame->prev_func.addr = 0;
2397 /* Discard the unwinder last, so that we can easily find it if an assertion
2398 in this function triggers. */
2399 frame->unwind = NULL;
2402 /* Set FRAME's unwinder temporarily, so that we can call a sniffer.
2403 Return a cleanup which should be called if unwinding fails, and
2404 discarded if it succeeds. */
2407 frame_prepare_for_sniffer (struct frame_info *frame,
2408 const struct frame_unwind *unwind)
2410 gdb_assert (frame->unwind == NULL);
2411 frame->unwind = unwind;
2412 return make_cleanup (frame_cleanup_after_sniffer, frame);
2415 extern initialize_file_ftype _initialize_frame; /* -Wmissing-prototypes */
2417 static struct cmd_list_element *set_backtrace_cmdlist;
2418 static struct cmd_list_element *show_backtrace_cmdlist;
2421 set_backtrace_cmd (char *args, int from_tty)
2423 help_list (set_backtrace_cmdlist, "set backtrace ", -1, gdb_stdout);
2427 show_backtrace_cmd (char *args, int from_tty)
2429 cmd_show_list (show_backtrace_cmdlist, from_tty, "");
2433 _initialize_frame (void)
2435 obstack_init (&frame_cache_obstack);
2437 observer_attach_target_changed (frame_observer_target_changed);
2439 add_prefix_cmd ("backtrace", class_maintenance, set_backtrace_cmd, _("\
2440 Set backtrace specific variables.\n\
2441 Configure backtrace variables such as the backtrace limit"),
2442 &set_backtrace_cmdlist, "set backtrace ",
2443 0/*allow-unknown*/, &setlist);
2444 add_prefix_cmd ("backtrace", class_maintenance, show_backtrace_cmd, _("\
2445 Show backtrace specific variables\n\
2446 Show backtrace variables such as the backtrace limit"),
2447 &show_backtrace_cmdlist, "show backtrace ",
2448 0/*allow-unknown*/, &showlist);
2450 add_setshow_boolean_cmd ("past-main", class_obscure,
2451 &backtrace_past_main, _("\
2452 Set whether backtraces should continue past \"main\"."), _("\
2453 Show whether backtraces should continue past \"main\"."), _("\
2454 Normally the caller of \"main\" is not of interest, so GDB will terminate\n\
2455 the backtrace at \"main\". Set this variable if you need to see the rest\n\
2456 of the stack trace."),
2458 show_backtrace_past_main,
2459 &set_backtrace_cmdlist,
2460 &show_backtrace_cmdlist);
2462 add_setshow_boolean_cmd ("past-entry", class_obscure,
2463 &backtrace_past_entry, _("\
2464 Set whether backtraces should continue past the entry point of a program."),
2466 Show whether backtraces should continue past the entry point of a program."),
2468 Normally there are no callers beyond the entry point of a program, so GDB\n\
2469 will terminate the backtrace there. Set this variable if you need to see\n\
2470 the rest of the stack trace."),
2472 show_backtrace_past_entry,
2473 &set_backtrace_cmdlist,
2474 &show_backtrace_cmdlist);
2476 add_setshow_integer_cmd ("limit", class_obscure,
2477 &backtrace_limit, _("\
2478 Set an upper bound on the number of backtrace levels."), _("\
2479 Show the upper bound on the number of backtrace levels."), _("\
2480 No more than the specified number of frames can be displayed or examined.\n\
2481 Zero is unlimited."),
2483 show_backtrace_limit,
2484 &set_backtrace_cmdlist,
2485 &show_backtrace_cmdlist);
2487 /* Debug this files internals. */
2488 add_setshow_zinteger_cmd ("frame", class_maintenance, &frame_debug, _("\
2489 Set frame debugging."), _("\
2490 Show frame debugging."), _("\
2491 When non-zero, frame specific internal debugging is enabled."),
2494 &setdebuglist, &showdebuglist);