1 /* Inline frame unwinder for GDB. 2 3 Copyright (C) 2008 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 "symtab.h" 26 #include "vec.h" 27 28 #include "gdb_assert.h" 29 30 /* We need to save a few variables for every thread stopped at the 31 virtual call site of an inlined function. If there was always a 32 "struct thread_info", we could hang it off that; in the mean time, 33 keep our own list. */ 34 struct inline_state 35 { 36 /* The thread this data relates to. It should be a currently 37 stopped thread; we assume thread IDs never change while the 38 thread is stopped. */ 39 ptid_t ptid; 40 41 /* The number of inlined functions we are skipping. Each of these 42 functions can be stepped in to. */ 43 int skipped_frames; 44 45 /* Only valid if SKIPPED_FRAMES is non-zero. This is the PC used 46 when calculating SKIPPED_FRAMES; used to check whether we have 47 moved to a new location by user request. If so, we invalidate 48 any skipped frames. */ 49 CORE_ADDR saved_pc; 50 51 /* Only valid if SKIPPED_FRAMES is non-zero. This is the symbol 52 of the outermost skipped inline function. It's used to find the 53 call site of the current frame. */ 54 struct symbol *skipped_symbol; 55 }; 56 57 typedef struct inline_state inline_state_s; 58 DEF_VEC_O(inline_state_s); 59 60 static VEC(inline_state_s) *inline_states; 61 62 /* Locate saved inlined frame state for PTID, if it exists. */ 63 64 static struct inline_state * 65 find_inline_frame_state (ptid_t ptid) 66 { 67 struct inline_state *state; 68 int ix; 69 70 for (ix = 0; VEC_iterate (inline_state_s, inline_states, ix, state); ix++) 71 { 72 if (ptid_equal (state->ptid, ptid)) 73 return state; 74 } 75 76 return NULL; 77 } 78 79 /* Allocate saved inlined frame state for PTID. */ 80 81 static struct inline_state * 82 allocate_inline_frame_state (ptid_t ptid) 83 { 84 struct inline_state *state; 85 86 state = VEC_safe_push (inline_state_s, inline_states, NULL); 87 memset (state, 0, sizeof (*state)); 88 state->ptid = ptid; 89 90 return state; 91 } 92 93 /* Forget about any hidden inlined functions in PTID, which is new or 94 about to be resumed. PTID may be minus_one_ptid (all processes) 95 or a PID (all threads in this process). */ 96 97 void 98 clear_inline_frame_state (ptid_t ptid) 99 { 100 struct inline_state *state; 101 int ix; 102 103 if (ptid_equal (ptid, minus_one_ptid)) 104 { 105 VEC_free (inline_state_s, inline_states); 106 return; 107 } 108 109 if (ptid_is_pid (ptid)) 110 { 111 VEC (inline_state_s) *new_states = NULL; 112 int pid = ptid_get_pid (ptid); 113 for (ix = 0; VEC_iterate (inline_state_s, inline_states, ix, state); ix++) 114 if (pid != ptid_get_pid (state->ptid)) 115 VEC_safe_push (inline_state_s, new_states, state); 116 VEC_free (inline_state_s, inline_states); 117 inline_states = new_states; 118 return; 119 } 120 121 for (ix = 0; VEC_iterate (inline_state_s, inline_states, ix, state); ix++) 122 if (ptid_equal (state->ptid, ptid)) 123 { 124 VEC_unordered_remove (inline_state_s, inline_states, ix); 125 return; 126 } 127 } 128 129 static void 130 inline_frame_this_id (struct frame_info *this_frame, 131 void **this_cache, 132 struct frame_id *this_id) 133 { 134 struct symbol *func; 135 136 /* In order to have a stable frame ID for a given inline function, 137 we must get the stack / special addresses from the underlying 138 real frame's this_id method. So we must call get_prev_frame. 139 Because we are inlined into some function, there must be previous 140 frames, so this is safe - as long as we're careful not to 141 create any cycles. */ 142 *this_id = get_frame_id (get_prev_frame (this_frame)); 143 144 /* We need a valid frame ID, so we need to be based on a valid 145 frame. FSF submission NOTE: this would be a good assertion to 146 apply to all frames, all the time. That would fix the ambiguity 147 of null_frame_id (between "no/any frame" and "the outermost 148 frame"). This will take work. */ 149 gdb_assert (frame_id_p (*this_id)); 150 151 /* For now, require we don't match outer_frame_id either (see 152 comment above). */ 153 gdb_assert (!frame_id_eq (*this_id, outer_frame_id)); 154 155 /* Future work NOTE: Alexandre Oliva applied a patch to GCC 4.3 156 which generates DW_AT_entry_pc for inlined functions when 157 possible. If this attribute is available, we should use it 158 in the frame ID (and eventually, to set breakpoints). */ 159 func = get_frame_function (this_frame); 160 gdb_assert (func != NULL); 161 (*this_id).code_addr = BLOCK_START (SYMBOL_BLOCK_VALUE (func)); 162 (*this_id).inline_depth++; 163 } 164 165 static struct value * 166 inline_frame_prev_register (struct frame_info *this_frame, void **this_cache, 167 int regnum) 168 { 169 /* Use get_frame_register_value instead of 170 frame_unwind_got_register, to avoid requiring this frame's ID. 171 This frame's ID depends on the previous frame's ID (unusual), and 172 the previous frame's ID depends on this frame's unwound 173 registers. If unwinding registers from this frame called 174 get_frame_id, there would be a loop. 175 176 Do not copy this code into any other unwinder! Inlined functions 177 are special; other unwinders must not have a dependency on the 178 previous frame's ID, and therefore can and should use 179 frame_unwind_got_register instead. */ 180 return get_frame_register_value (this_frame, regnum); 181 } 182 183 /* Check whether we are at an inlining site that does not already 184 have an associated frame. */ 185 186 static int 187 inline_frame_sniffer (const struct frame_unwind *self, 188 struct frame_info *this_frame, 189 void **this_cache) 190 { 191 CORE_ADDR this_pc; 192 struct block *frame_block, *cur_block; 193 int depth; 194 struct frame_info *next_frame; 195 struct inline_state *state = find_inline_frame_state (inferior_ptid); 196 197 this_pc = get_frame_address_in_block (this_frame); 198 frame_block = block_for_pc (this_pc); 199 if (frame_block == NULL) 200 return 0; 201 202 /* Calculate DEPTH, the number of inlined functions at this 203 location. */ 204 depth = 0; 205 cur_block = frame_block; 206 while (BLOCK_SUPERBLOCK (cur_block)) 207 { 208 if (block_inlined_p (cur_block)) 209 depth++; 210 211 cur_block = BLOCK_SUPERBLOCK (cur_block); 212 } 213 214 /* Check how many inlined functions already have frames. */ 215 for (next_frame = get_next_frame (this_frame); 216 next_frame && get_frame_type (next_frame) == INLINE_FRAME; 217 next_frame = get_next_frame (next_frame)) 218 { 219 gdb_assert (depth > 0); 220 depth--; 221 } 222 223 /* If this is the topmost frame, or all frames above us are inlined, 224 then check whether we were requested to skip some frames (so they 225 can be stepped into later). */ 226 if (state != NULL && state->skipped_frames > 0 && next_frame == NULL) 227 { 228 if (this_pc != state->saved_pc) 229 state->skipped_frames = 0; 230 else 231 { 232 gdb_assert (depth >= state->skipped_frames); 233 depth -= state->skipped_frames; 234 } 235 } 236 237 /* If all the inlined functions here already have frames, then pass 238 to the normal unwinder for this PC. */ 239 if (depth == 0) 240 return 0; 241 242 /* If the next frame is an inlined function, but not the outermost, then 243 we are the next outer. If it is not an inlined function, then we 244 are the innermost inlined function of a different real frame. */ 245 return 1; 246 } 247 248 const struct frame_unwind inline_frame_unwinder = { 249 INLINE_FRAME, 250 inline_frame_this_id, 251 inline_frame_prev_register, 252 NULL, 253 inline_frame_sniffer 254 }; 255 256 const struct frame_unwind *const inline_frame_unwind = &inline_frame_unwinder; 257 258 /* Return non-zero if BLOCK, an inlined function block containing PC, 259 has a group of contiguous instructions starting at PC (but not 260 before it). */ 261 262 static int 263 block_starting_point_at (CORE_ADDR pc, struct block *block) 264 { 265 struct blockvector *bv; 266 struct block *new_block; 267 268 bv = blockvector_for_pc (pc, NULL); 269 if (BLOCKVECTOR_MAP (bv) == NULL) 270 return 0; 271 272 new_block = addrmap_find (BLOCKVECTOR_MAP (bv), pc - 1); 273 if (new_block == NULL) 274 return 1; 275 276 if (new_block == block || contained_in (new_block, block)) 277 return 0; 278 279 /* The immediately preceeding address belongs to a different block, 280 which is not a child of this one. Treat this as an entrance into 281 BLOCK. */ 282 return 1; 283 } 284 285 /* Skip all inlined functions whose call sites are at the current PC. 286 Frames for the hidden functions will not appear in the backtrace until the 287 user steps into them. */ 288 289 void 290 skip_inline_frames (ptid_t ptid) 291 { 292 CORE_ADDR this_pc; 293 struct block *frame_block, *cur_block; 294 struct symbol *last_sym = NULL; 295 int skip_count = 0; 296 struct inline_state *state; 297 298 /* This function is called right after reinitializing the frame 299 cache. We try not to do more unwinding than absolutely 300 necessary, for performance. */ 301 this_pc = get_frame_pc (get_current_frame ()); 302 frame_block = block_for_pc (this_pc); 303 304 if (frame_block != NULL) 305 { 306 cur_block = frame_block; 307 while (BLOCK_SUPERBLOCK (cur_block)) 308 { 309 if (block_inlined_p (cur_block)) 310 { 311 /* See comments in inline_frame_this_id about this use 312 of BLOCK_START. */ 313 if (BLOCK_START (cur_block) == this_pc 314 || block_starting_point_at (this_pc, cur_block)) 315 { 316 skip_count++; 317 last_sym = BLOCK_FUNCTION (cur_block); 318 } 319 else 320 break; 321 } 322 cur_block = BLOCK_SUPERBLOCK (cur_block); 323 } 324 } 325 326 gdb_assert (find_inline_frame_state (ptid) == NULL); 327 state = allocate_inline_frame_state (ptid); 328 state->skipped_frames = skip_count; 329 state->saved_pc = this_pc; 330 state->skipped_symbol = last_sym; 331 332 if (skip_count != 0) 333 reinit_frame_cache (); 334 } 335 336 /* Step into an inlined function by unhiding it. */ 337 338 void 339 step_into_inline_frame (ptid_t ptid) 340 { 341 struct inline_state *state = find_inline_frame_state (ptid); 342 343 gdb_assert (state != NULL && state->skipped_frames > 0); 344 state->skipped_frames--; 345 reinit_frame_cache (); 346 } 347 348 /* Return the number of hidden functions inlined into the current 349 frame. */ 350 351 int 352 inline_skipped_frames (ptid_t ptid) 353 { 354 struct inline_state *state = find_inline_frame_state (ptid); 355 356 if (state == NULL) 357 return 0; 358 else 359 return state->skipped_frames; 360 } 361 362 /* If one or more inlined functions are hidden, return the symbol for 363 the function inlined into the current frame. */ 364 365 struct symbol * 366 inline_skipped_symbol (ptid_t ptid) 367 { 368 struct inline_state *state = find_inline_frame_state (ptid); 369 370 gdb_assert (state != NULL); 371 return state->skipped_symbol; 372 } 373 374 /* Return the number of functions inlined into THIS_FRAME. Some of 375 the callees may not have associated frames (see 376 skip_inline_frames). */ 377 378 int 379 frame_inlined_callees (struct frame_info *this_frame) 380 { 381 struct frame_info *next_frame; 382 int inline_count = 0; 383 384 /* First count how many inlined functions at this PC have frames 385 above FRAME (are inlined into FRAME). */ 386 for (next_frame = get_next_frame (this_frame); 387 next_frame && get_frame_type (next_frame) == INLINE_FRAME; 388 next_frame = get_next_frame (next_frame)) 389 inline_count++; 390 391 /* Simulate some most-inner inlined frames which were suppressed, so 392 they can be stepped into later. If we are unwinding already 393 outer frames from some non-inlined frame this does not apply. */ 394 if (next_frame == NULL) 395 inline_count += inline_skipped_frames (inferior_ptid); 396 397 return inline_count; 398 } 399