gdb/inline-frame.c - gdb

Global variables defined

Data types defined

Functions defined

Source code

  1. /* Inline frame unwinder for GDB.

  3.    Copyright (C) 2008-2015 Free Software Foundation, Inc.

  5.    This file is part of GDB.

  7.    This program is free software; you can redistribute it and/or modify
  8.    it under the terms of the GNU General Public License as published by
  9.    the Free Software Foundation; either version 3 of the License, or
  10.    (at your option) any later version.

  12.    This program is distributed in the hope that it will be useful,
  13.    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14.    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15.    GNU General Public License for more details.

  17.    You should have received a copy of the GNU General Public License
  18.    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

  20. #include "defs.h"
  21. #include "inline-frame.h"
  22. #include "addrmap.h"
  23. #include "block.h"
  24. #include "frame-unwind.h"
  25. #include "inferior.h"
  26. #include "regcache.h"
  27. #include "symtab.h"
  28. #include "vec.h"
  29. #include "frame.h"

  31. /* We need to save a few variables for every thread stopped at the
  32.    virtual call site of an inlined function.  If there was always a
  33.    "struct thread_info", we could hang it off that; in the mean time,
  34.    keep our own list.  */
  35. ‌struct inline_state
  36. {
  37.   /* The thread this data relates to.  It should be a currently
  38.      stopped thread; we assume thread IDs never change while the
  39.      thread is stopped.  */
  40.   ptid_t ptid;

  42.   /* The number of inlined functions we are skipping.  Each of these
  43.      functions can be stepped in to.  */
  44.   int skipped_frames;

  46.   /* Only valid if SKIPPED_FRAMES is non-zero.  This is the PC used
  47.      when calculating SKIPPED_FRAMES; used to check whether we have
  48.      moved to a new location by user request.  If so, we invalidate
  49.      any skipped frames.  */
  50.   CORE_ADDR saved_pc;

  52.   /* Only valid if SKIPPED_FRAMES is non-zero.  This is the symbol
  53.      of the outermost skipped inline function.  It's used to find the
  54.      call site of the current frame.  */
  55.   struct symbol *skipped_symbol;
  56. };

  58. ‌typedef struct inline_state inline_state_s;
  59. ‌DEF_VEC_O(inline_state_s);

  61. static VEC(inline_state_s) *inline_states;

  63. /* Locate saved inlined frame state for PTID, if it exists
  64.    and is valid.  */

  66. static struct inline_state *
  67. ‌find_inline_frame_state (ptid_t ptid)
  68. {
  69.   struct inline_state *state;
  70.   int ix;

  72.   for (ix = 0; VEC_iterate (inline_state_s, inline_states, ix, state); ix++)
  73.     {
  74.       if (ptid_equal (state->ptid, ptid))
  75.         {
  76.           struct regcache *regcache = get_thread_regcache (ptid);
  77.           CORE_ADDR current_pc = regcache_read_pc (regcache);

  79.           if (current_pc != state->saved_pc)
  80.             {
  81.               /* PC has changed - this context is invalid.  Use the
  82.                  default behavior.  */
  83.               VEC_unordered_remove (inline_state_s, inline_states, ix);
  84.               return NULL;
  85.             }
  86.           else
  87.             return state;
  88.         }
  89.     }

  91.   return NULL;
  92. }

  94. /* Allocate saved inlined frame state for PTID.  */

  96. static struct inline_state *
  97. ‌allocate_inline_frame_state (ptid_t ptid)
  98. {
  99.   struct inline_state *state;

  101.   state = VEC_safe_push (inline_state_s, inline_states, NULL);
  102.   memset (state, 0, sizeof (*state));
  103.   state->ptid = ptid;

  105.   return state;
  106. }

  108. /* Forget about any hidden inlined functions in PTID, which is new or
  109.    about to be resumed.  PTID may be minus_one_ptid (all processes)
  110.    or a PID (all threads in this process).  */

  112. void
  113. ‌clear_inline_frame_state (ptid_t ptid)
  114. {
  115.   struct inline_state *state;
  116.   int ix;

  118.   if (ptid_equal (ptid, minus_one_ptid))
  119.     {
  120.       VEC_free (inline_state_s, inline_states);
  121.       return;
  122.     }

  124.   if (ptid_is_pid (ptid))
  125.     {
  126.       VEC (inline_state_s) *new_states = NULL;
  127.       int pid = ptid_get_pid (ptid);

  129.       for (ix = 0;
  130.            VEC_iterate (inline_state_s, inline_states, ix, state);
  131.            ix++)
  132.         if (pid != ptid_get_pid (state->ptid))
  133.           VEC_safe_push (inline_state_s, new_states, state);
  134.       VEC_free (inline_state_s, inline_states);
  135.       inline_states = new_states;
  136.       return;
  137.     }

  139.   for (ix = 0; VEC_iterate (inline_state_s, inline_states, ix, state); ix++)
  140.     if (ptid_equal (state->ptid, ptid))
  141.       {
  142.         VEC_unordered_remove (inline_state_s, inline_states, ix);
  143.         return;
  144.       }
  145. }

  147. static void
  148. ‌inline_frame_this_id (struct frame_info *this_frame,
  149.                       void **this_cache,
  150.                       struct frame_id *this_id)
  151. {
  152.   struct symbol *func;

  154.   /* In order to have a stable frame ID for a given inline function,
  155.      we must get the stack / special addresses from the underlying
  156.      real frame's this_id method.  So we must call
  157.      get_prev_frame_always.  Because we are inlined into some
  158.      function, there must be previous frames, so this is safe - as
  159.      long as we're careful not to create any cycles.  */
  160.   *this_id = get_frame_id (get_prev_frame_always (this_frame));

  162.   /* We need a valid frame ID, so we need to be based on a valid
  163.      frame.  FSF submission NOTE: this would be a good assertion to
  164.      apply to all frames, all the time.  That would fix the ambiguity
  165.      of null_frame_id (between "no/any frame" and "the outermost
  166.      frame").  This will take work.  */
  167.   gdb_assert (frame_id_p (*this_id));

  169.   /* For now, require we don't match outer_frame_id either (see
  170.      comment above).  */
  171.   gdb_assert (!frame_id_eq (*this_id, outer_frame_id));

  173.   /* Future work NOTE: Alexandre Oliva applied a patch to GCC 4.3
  174.      which generates DW_AT_entry_pc for inlined functions when
  175.      possible.  If this attribute is available, we should use it
  176.      in the frame ID (and eventually, to set breakpoints).  */
  177.   func = get_frame_function (this_frame);
  178.   gdb_assert (func != NULL);
  179.   (*this_id).code_addr = BLOCK_START (SYMBOL_BLOCK_VALUE (func));
  180.   (*this_id).artificial_depth++;
  181. }

  183. static struct value *
  184. ‌inline_frame_prev_register (struct frame_info *this_frame, void **this_cache,
  185.                             int regnum)
  186. {
  187.   /* Use get_frame_register_value instead of
  188.      frame_unwind_got_register, to avoid requiring this frame's ID.
  189.      This frame's ID depends on the previous frame's ID (unusual), and
  190.      the previous frame's ID depends on this frame's unwound
  191.      registers.  If unwinding registers from this frame called
  192.      get_frame_id, there would be a loop.

  194.      Do not copy this code into any other unwinder!  Inlined functions
  195.      are special; other unwinders must not have a dependency on the
  196.      previous frame's ID, and therefore can and should use
  197.      frame_unwind_got_register instead.  */
  198.   return get_frame_register_value (this_frame, regnum);
  199. }

  201. /* Check whether we are at an inlining site that does not already
  202.    have an associated frame.  */

  204. static int
  205. ‌inline_frame_sniffer (const struct frame_unwind *self,
  206.                       struct frame_info *this_frame,
  207.                       void **this_cache)
  208. {
  209.   CORE_ADDR this_pc;
  210.   const struct block *frame_block, *cur_block;
  211.   int depth;
  212.   struct frame_info *next_frame;
  213.   struct inline_state *state = find_inline_frame_state (inferior_ptid);

  215.   this_pc = get_frame_address_in_block (this_frame);
  216.   frame_block = block_for_pc (this_pc);
  217.   if (frame_block == NULL)
  218.     return 0;

  220.   /* Calculate DEPTH, the number of inlined functions at this
  221.      location.  */
  222.   depth = 0;
  223.   cur_block = frame_block;
  224.   while (BLOCK_SUPERBLOCK (cur_block))
  225.     {
  226.       if (block_inlined_p (cur_block))
  227.         depth++;

  229.       cur_block = BLOCK_SUPERBLOCK (cur_block);
  230.     }

  232.   /* Check how many inlined functions already have frames.  */
  233.   for (next_frame = get_next_frame (this_frame);
  234.        next_frame && get_frame_type (next_frame) == INLINE_FRAME;
  235.        next_frame = get_next_frame (next_frame))
  236.     {
  237.       gdb_assert (depth > 0);
  238.       depth--;
  239.     }

  241.   /* If this is the topmost frame, or all frames above us are inlined,
  242.      then check whether we were requested to skip some frames (so they
  243.      can be stepped into later).  */
  244.   if (state != NULL && state->skipped_frames > 0 && next_frame == NULL)
  245.     {
  246.       gdb_assert (depth >= state->skipped_frames);
  247.       depth -= state->skipped_frames;
  248.     }

  250.   /* If all the inlined functions here already have frames, then pass
  251.      to the normal unwinder for this PC.  */
  252.   if (depth == 0)
  253.     return 0;

  255.   /* If the next frame is an inlined function, but not the outermost, then
  256.      we are the next outer.  If it is not an inlined function, then we
  257.      are the innermost inlined function of a different real frame.  */
  258.   return 1;
  259. }

  261. ‌const struct frame_unwind inline_frame_unwind = {
  262.   INLINE_FRAME,
  263.   default_frame_unwind_stop_reason,
  264.   inline_frame_this_id,
  265.   inline_frame_prev_register,
  266.   NULL,
  267.   inline_frame_sniffer
  268. };

  270. /* Return non-zero if BLOCK, an inlined function block containing PC,
  271.    has a group of contiguous instructions starting at PC (but not
  272.    before it).  */

  274. static int
  275. ‌block_starting_point_at (CORE_ADDR pc, const struct block *block)
  276. {
  277.   const struct blockvector *bv;
  278.   struct block *new_block;

  280.   bv = blockvector_for_pc (pc, NULL);
  281.   if (BLOCKVECTOR_MAP (bv) == NULL)
  282.     return 0;

  284.   new_block = addrmap_find (BLOCKVECTOR_MAP (bv), pc - 1);
  285.   if (new_block == NULL)
  286.     return 1;

  288.   if (new_block == block || contained_in (new_block, block))
  289.     return 0;

  291.   /* The immediately preceding address belongs to a different block,
  292.      which is not a child of this one.  Treat this as an entrance into
  293.      BLOCK.  */
  294.   return 1;
  295. }

  297. /* Skip all inlined functions whose call sites are at the current PC.
  298.    Frames for the hidden functions will not appear in the backtrace until the
  299.    user steps into them.  */

  301. void
  302. ‌skip_inline_frames (ptid_t ptid)
  303. {
  304.   CORE_ADDR this_pc;
  305.   const struct block *frame_block, *cur_block;
  306.   struct symbol *last_sym = NULL;
  307.   int skip_count = 0;
  308.   struct inline_state *state;

  310.   /* This function is called right after reinitializing the frame
  311.      cache.  We try not to do more unwinding than absolutely
  312.      necessary, for performance.  */
  313.   this_pc = get_frame_pc (get_current_frame ());
  314.   frame_block = block_for_pc (this_pc);

  316.   if (frame_block != NULL)
  317.     {
  318.       cur_block = frame_block;
  319.       while (BLOCK_SUPERBLOCK (cur_block))
  320.         {
  321.           if (block_inlined_p (cur_block))
  322.             {
  323.               /* See comments in inline_frame_this_id about this use
  324.                  of BLOCK_START.  */
  325.               if (BLOCK_START (cur_block) == this_pc
  326.                   || block_starting_point_at (this_pc, cur_block))
  327.                 {
  328.                   skip_count++;
  329.                   last_sym = BLOCK_FUNCTION (cur_block);
  330.                 }
  331.               else
  332.                 break;
  333.             }
  334.           cur_block = BLOCK_SUPERBLOCK (cur_block);
  335.         }
  336.     }

  338.   gdb_assert (find_inline_frame_state (ptid) == NULL);
  339.   state = allocate_inline_frame_state (ptid);
  340.   state->skipped_frames = skip_count;
  341.   state->saved_pc = this_pc;
  342.   state->skipped_symbol = last_sym;

  344.   if (skip_count != 0)
  345.     reinit_frame_cache ();
  346. }

  348. /* Step into an inlined function by unhiding it.  */

  350. void
  351. ‌step_into_inline_frame (ptid_t ptid)
  352. {
  353.   struct inline_state *state = find_inline_frame_state (ptid);

  355.   gdb_assert (state != NULL && state->skipped_frames > 0);
  356.   state->skipped_frames--;
  357.   reinit_frame_cache ();
  358. }

  360. /* Return the number of hidden functions inlined into the current
  361.    frame.  */

  363. int
  364. ‌inline_skipped_frames (ptid_t ptid)
  365. {
  366.   struct inline_state *state = find_inline_frame_state (ptid);

  368.   if (state == NULL)
  369.     return 0;
  370.   else
  371.     return state->skipped_frames;
  372. }

  374. /* If one or more inlined functions are hidden, return the symbol for
  375.    the function inlined into the current frame.  */

  377. struct symbol *
  378. ‌inline_skipped_symbol (ptid_t ptid)
  379. {
  380.   struct inline_state *state = find_inline_frame_state (ptid);

  382.   gdb_assert (state != NULL);
  383.   return state->skipped_symbol;
  384. }

  386. /* Return the number of functions inlined into THIS_FRAME.  Some of
  387.    the callees may not have associated frames (see
  388.    skip_inline_frames).  */

  390. int
  391. ‌frame_inlined_callees (struct frame_info *this_frame)
  392. {
  393.   struct frame_info *next_frame;
  394.   int inline_count = 0;

  396.   /* First count how many inlined functions at this PC have frames
  397.      above FRAME (are inlined into FRAME).  */
  398.   for (next_frame = get_next_frame (this_frame);
  399.        next_frame && get_frame_type (next_frame) == INLINE_FRAME;
  400.        next_frame = get_next_frame (next_frame))
  401.     inline_count++;

  403.   /* Simulate some most-inner inlined frames which were suppressed, so
  404.      they can be stepped into later.  If we are unwinding already
  405.      outer frames from some non-inlined frame this does not apply.  */
  406.   if (next_frame == NULL)
  407.     inline_count += inline_skipped_frames (inferior_ptid);

  409.   return inline_count;
  410. }