1 /* Inline frame unwinder for GDB. 2 3 Copyright (C) 2008, 2009, 2010 Free Software Foundation, Inc. 4 5 This file is part of GDB. 6 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. 11 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. 16 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/>. */ 19 20 #include "defs.h" 21 #include "addrmap.h" 22 #include "block.h" 23 #include "frame-unwind.h" 24 #include "inferior.h" 25 #include "regcache.h" 26 #include "symtab.h" 27 #include "vec.h" 28 29 #include "gdb_assert.h" 30 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; 41 42 /* The number of inlined functions we are skipping. Each of these 43 functions can be stepped in to. */ 44 int skipped_frames; 45 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; 51 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 }; 57 58 typedef struct inline_state inline_state_s; 59 DEF_VEC_O(inline_state_s); 60 61 static VEC(inline_state_s) *inline_states; 62 63 /* Locate saved inlined frame state for PTID, if it exists 64 and is valid. */ 65 66 static struct inline_state * 67 find_inline_frame_state (ptid_t ptid) 68 { 69 struct inline_state *state; 70 int ix; 71 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); 78 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 } 90 91 return NULL; 92 } 93 94 /* Allocate saved inlined frame state for PTID. */ 95 96 static struct inline_state * 97 allocate_inline_frame_state (ptid_t ptid) 98 { 99 struct inline_state *state; 100 101 state = VEC_safe_push (inline_state_s, inline_states, NULL); 102 memset (state, 0, sizeof (*state)); 103 state->ptid = ptid; 104 105 return state; 106 } 107 108 /* 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). */ 111 112 void 113 clear_inline_frame_state (ptid_t ptid) 114 { 115 struct inline_state *state; 116 int ix; 117 118 if (ptid_equal (ptid, minus_one_ptid)) 119 { 120 VEC_free (inline_state_s, inline_states); 121 return; 122 } 123 124 if (ptid_is_pid (ptid)) 125 { 126 VEC (inline_state_s) *new_states = NULL; 127 int pid = ptid_get_pid (ptid); 128 129 for (ix = 0; VEC_iterate (inline_state_s, inline_states, ix, state); ix++) 130 if (pid != ptid_get_pid (state->ptid)) 131 VEC_safe_push (inline_state_s, new_states, state); 132 VEC_free (inline_state_s, inline_states); 133 inline_states = new_states; 134 return; 135 } 136 137 for (ix = 0; VEC_iterate (inline_state_s, inline_states, ix, state); ix++) 138 if (ptid_equal (state->ptid, ptid)) 139 { 140 VEC_unordered_remove (inline_state_s, inline_states, ix); 141 return; 142 } 143 } 144 145 static void 146 inline_frame_this_id (struct frame_info *this_frame, 147 void **this_cache, 148 struct frame_id *this_id) 149 { 150 struct symbol *func; 151 152 /* In order to have a stable frame ID for a given inline function, 153 we must get the stack / special addresses from the underlying 154 real frame's this_id method. So we must call get_prev_frame. 155 Because we are inlined into some function, there must be previous 156 frames, so this is safe - as long as we're careful not to 157 create any cycles. */ 158 *this_id = get_frame_id (get_prev_frame (this_frame)); 159 160 /* We need a valid frame ID, so we need to be based on a valid 161 frame. FSF submission NOTE: this would be a good assertion to 162 apply to all frames, all the time. That would fix the ambiguity 163 of null_frame_id (between "no/any frame" and "the outermost 164 frame"). This will take work. */ 165 gdb_assert (frame_id_p (*this_id)); 166 167 /* For now, require we don't match outer_frame_id either (see 168 comment above). */ 169 gdb_assert (!frame_id_eq (*this_id, outer_frame_id)); 170 171 /* Future work NOTE: Alexandre Oliva applied a patch to GCC 4.3 172 which generates DW_AT_entry_pc for inlined functions when 173 possible. If this attribute is available, we should use it 174 in the frame ID (and eventually, to set breakpoints). */ 175 func = get_frame_function (this_frame); 176 gdb_assert (func != NULL); 177 (*this_id).code_addr = BLOCK_START (SYMBOL_BLOCK_VALUE (func)); 178 (*this_id).inline_depth++; 179 } 180 181 static struct value * 182 inline_frame_prev_register (struct frame_info *this_frame, void **this_cache, 183 int regnum) 184 { 185 /* Use get_frame_register_value instead of 186 frame_unwind_got_register, to avoid requiring this frame's ID. 187 This frame's ID depends on the previous frame's ID (unusual), and 188 the previous frame's ID depends on this frame's unwound 189 registers. If unwinding registers from this frame called 190 get_frame_id, there would be a loop. 191 192 Do not copy this code into any other unwinder! Inlined functions 193 are special; other unwinders must not have a dependency on the 194 previous frame's ID, and therefore can and should use 195 frame_unwind_got_register instead. */ 196 return get_frame_register_value (this_frame, regnum); 197 } 198 199 /* Check whether we are at an inlining site that does not already 200 have an associated frame. */ 201 202 static int 203 inline_frame_sniffer (const struct frame_unwind *self, 204 struct frame_info *this_frame, 205 void **this_cache) 206 { 207 CORE_ADDR this_pc; 208 struct block *frame_block, *cur_block; 209 int depth; 210 struct frame_info *next_frame; 211 struct inline_state *state = find_inline_frame_state (inferior_ptid); 212 213 this_pc = get_frame_address_in_block (this_frame); 214 frame_block = block_for_pc (this_pc); 215 if (frame_block == NULL) 216 return 0; 217 218 /* Calculate DEPTH, the number of inlined functions at this 219 location. */ 220 depth = 0; 221 cur_block = frame_block; 222 while (BLOCK_SUPERBLOCK (cur_block)) 223 { 224 if (block_inlined_p (cur_block)) 225 depth++; 226 227 cur_block = BLOCK_SUPERBLOCK (cur_block); 228 } 229 230 /* Check how many inlined functions already have frames. */ 231 for (next_frame = get_next_frame (this_frame); 232 next_frame && get_frame_type (next_frame) == INLINE_FRAME; 233 next_frame = get_next_frame (next_frame)) 234 { 235 gdb_assert (depth > 0); 236 depth--; 237 } 238 239 /* If this is the topmost frame, or all frames above us are inlined, 240 then check whether we were requested to skip some frames (so they 241 can be stepped into later). */ 242 if (state != NULL && state->skipped_frames > 0 && next_frame == NULL) 243 { 244 gdb_assert (depth >= state->skipped_frames); 245 depth -= state->skipped_frames; 246 } 247 248 /* If all the inlined functions here already have frames, then pass 249 to the normal unwinder for this PC. */ 250 if (depth == 0) 251 return 0; 252 253 /* If the next frame is an inlined function, but not the outermost, then 254 we are the next outer. If it is not an inlined function, then we 255 are the innermost inlined function of a different real frame. */ 256 return 1; 257 } 258 259 const struct frame_unwind inline_frame_unwinder = { 260 INLINE_FRAME, 261 inline_frame_this_id, 262 inline_frame_prev_register, 263 NULL, 264 inline_frame_sniffer 265 }; 266 267 const struct frame_unwind *const inline_frame_unwind = &inline_frame_unwinder; 268 269 /* Return non-zero if BLOCK, an inlined function block containing PC, 270 has a group of contiguous instructions starting at PC (but not 271 before it). */ 272 273 static int 274 block_starting_point_at (CORE_ADDR pc, struct block *block) 275 { 276 struct blockvector *bv; 277 struct block *new_block; 278 279 bv = blockvector_for_pc (pc, NULL); 280 if (BLOCKVECTOR_MAP (bv) == NULL) 281 return 0; 282 283 new_block = addrmap_find (BLOCKVECTOR_MAP (bv), pc - 1); 284 if (new_block == NULL) 285 return 1; 286 287 if (new_block == block || contained_in (new_block, block)) 288 return 0; 289 290 /* The immediately preceeding address belongs to a different block, 291 which is not a child of this one. Treat this as an entrance into 292 BLOCK. */ 293 return 1; 294 } 295 296 /* Skip all inlined functions whose call sites are at the current PC. 297 Frames for the hidden functions will not appear in the backtrace until the 298 user steps into them. */ 299 300 void 301 skip_inline_frames (ptid_t ptid) 302 { 303 CORE_ADDR this_pc; 304 struct block *frame_block, *cur_block; 305 struct symbol *last_sym = NULL; 306 int skip_count = 0; 307 struct inline_state *state; 308 309 /* This function is called right after reinitializing the frame 310 cache. We try not to do more unwinding than absolutely 311 necessary, for performance. */ 312 this_pc = get_frame_pc (get_current_frame ()); 313 frame_block = block_for_pc (this_pc); 314 315 if (frame_block != NULL) 316 { 317 cur_block = frame_block; 318 while (BLOCK_SUPERBLOCK (cur_block)) 319 { 320 if (block_inlined_p (cur_block)) 321 { 322 /* See comments in inline_frame_this_id about this use 323 of BLOCK_START. */ 324 if (BLOCK_START (cur_block) == this_pc 325 || block_starting_point_at (this_pc, cur_block)) 326 { 327 skip_count++; 328 last_sym = BLOCK_FUNCTION (cur_block); 329 } 330 else 331 break; 332 } 333 cur_block = BLOCK_SUPERBLOCK (cur_block); 334 } 335 } 336 337 gdb_assert (find_inline_frame_state (ptid) == NULL); 338 state = allocate_inline_frame_state (ptid); 339 state->skipped_frames = skip_count; 340 state->saved_pc = this_pc; 341 state->skipped_symbol = last_sym; 342 343 if (skip_count != 0) 344 reinit_frame_cache (); 345 } 346 347 /* Step into an inlined function by unhiding it. */ 348 349 void 350 step_into_inline_frame (ptid_t ptid) 351 { 352 struct inline_state *state = find_inline_frame_state (ptid); 353 354 gdb_assert (state != NULL && state->skipped_frames > 0); 355 state->skipped_frames--; 356 reinit_frame_cache (); 357 } 358 359 /* Return the number of hidden functions inlined into the current 360 frame. */ 361 362 int 363 inline_skipped_frames (ptid_t ptid) 364 { 365 struct inline_state *state = find_inline_frame_state (ptid); 366 367 if (state == NULL) 368 return 0; 369 else 370 return state->skipped_frames; 371 } 372 373 /* If one or more inlined functions are hidden, return the symbol for 374 the function inlined into the current frame. */ 375 376 struct symbol * 377 inline_skipped_symbol (ptid_t ptid) 378 { 379 struct inline_state *state = find_inline_frame_state (ptid); 380 381 gdb_assert (state != NULL); 382 return state->skipped_symbol; 383 } 384 385 /* Return the number of functions inlined into THIS_FRAME. Some of 386 the callees may not have associated frames (see 387 skip_inline_frames). */ 388 389 int 390 frame_inlined_callees (struct frame_info *this_frame) 391 { 392 struct frame_info *next_frame; 393 int inline_count = 0; 394 395 /* First count how many inlined functions at this PC have frames 396 above FRAME (are inlined into FRAME). */ 397 for (next_frame = get_next_frame (this_frame); 398 next_frame && get_frame_type (next_frame) == INLINE_FRAME; 399 next_frame = get_next_frame (next_frame)) 400 inline_count++; 401 402 /* Simulate some most-inner inlined frames which were suppressed, so 403 they can be stepped into later. If we are unwinding already 404 outer frames from some non-inlined frame this does not apply. */ 405 if (next_frame == NULL) 406 inline_count += inline_skipped_frames (inferior_ptid); 407 408 return inline_count; 409 } 410