Mercurial > hg > CbC > CbC_gcc
annotate gcc/cfganal.c @ 120:f93fa5091070
fix conv1.c
| author | mir3636 |
|---|---|
| date | Thu, 08 Mar 2018 14:53:42 +0900 |
| parents | 04ced10e8804 |
| children | 84e7813d76e9 |
| rev | line source |
|---|---|
| 0 | 1 /* Control flow graph analysis code for GNU compiler. |
| 111 | 2 Copyright (C) 1987-2017 Free Software Foundation, Inc. |
| 0 | 3 |
| 4 This file is part of GCC. | |
| 5 | |
| 6 GCC is free software; you can redistribute it and/or modify it under | |
| 7 the terms of the GNU General Public License as published by the Free | |
| 8 Software Foundation; either version 3, or (at your option) any later | |
| 9 version. | |
| 10 | |
| 11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY | |
| 12 WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
| 13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
| 14 for more details. | |
| 15 | |
| 16 You should have received a copy of the GNU General Public License | |
| 17 along with GCC; see the file COPYING3. If not see | |
| 18 <http://www.gnu.org/licenses/>. */ | |
| 19 | |
| 20 /* This file contains various simple utilities to analyze the CFG. */ | |
| 111 | 21 |
| 0 | 22 #include "config.h" |
| 23 #include "system.h" | |
| 24 #include "coretypes.h" | |
| 111 | 25 #include "backend.h" |
| 26 #include "cfghooks.h" | |
| 0 | 27 #include "timevar.h" |
| 111 | 28 #include "cfganal.h" |
| 29 #include "cfgloop.h" | |
| 0 | 30 |
| 111 | 31 namespace { |
| 0 | 32 /* Store the data structures necessary for depth-first search. */ |
| 111 | 33 class depth_first_search |
| 34 { | |
| 35 public: | |
| 36 depth_first_search (); | |
| 37 | |
| 38 basic_block execute (basic_block); | |
| 39 void add_bb (basic_block); | |
| 40 | |
| 41 private: | |
| 0 | 42 /* stack for backtracking during the algorithm */ |
| 111 | 43 auto_vec<basic_block, 20> m_stack; |
| 0 | 44 |
| 45 /* record of basic blocks already seen by depth-first search */ | |
| 111 | 46 auto_sbitmap m_visited_blocks; |
| 0 | 47 }; |
| 48 } | |
| 49 | |
| 50 /* Mark the back edges in DFS traversal. | |
| 51 Return nonzero if a loop (natural or otherwise) is present. | |
| 52 Inspired by Depth_First_Search_PP described in: | |
| 53 | |
| 54 Advanced Compiler Design and Implementation | |
| 55 Steven Muchnick | |
| 56 Morgan Kaufmann, 1997 | |
| 57 | |
| 58 and heavily borrowed from pre_and_rev_post_order_compute. */ | |
| 59 | |
| 60 bool | |
| 61 mark_dfs_back_edges (void) | |
| 62 { | |
| 63 int *pre; | |
| 64 int *post; | |
| 65 int prenum = 1; | |
| 66 int postnum = 1; | |
| 67 bool found = false; | |
| 68 | |
| 69 /* Allocate the preorder and postorder number arrays. */ | |
| 111 | 70 pre = XCNEWVEC (int, last_basic_block_for_fn (cfun)); |
| 71 post = XCNEWVEC (int, last_basic_block_for_fn (cfun)); | |
| 0 | 72 |
| 73 /* Allocate stack for back-tracking up CFG. */ | |
| 111 | 74 auto_vec<edge_iterator, 20> stack (n_basic_blocks_for_fn (cfun) + 1); |
| 0 | 75 |
| 76 /* Allocate bitmap to track nodes that have been visited. */ | |
| 111 | 77 auto_sbitmap visited (last_basic_block_for_fn (cfun)); |
| 0 | 78 |
| 79 /* None of the nodes in the CFG have been visited yet. */ | |
| 111 | 80 bitmap_clear (visited); |
| 0 | 81 |
| 82 /* Push the first edge on to the stack. */ | |
| 111 | 83 stack.quick_push (ei_start (ENTRY_BLOCK_PTR_FOR_FN (cfun)->succs)); |
| 0 | 84 |
| 111 | 85 while (!stack.is_empty ()) |
| 0 | 86 { |
| 87 basic_block src; | |
| 88 basic_block dest; | |
| 89 | |
| 90 /* Look at the edge on the top of the stack. */ | |
| 111 | 91 edge_iterator ei = stack.last (); |
| 0 | 92 src = ei_edge (ei)->src; |
| 93 dest = ei_edge (ei)->dest; | |
| 94 ei_edge (ei)->flags &= ~EDGE_DFS_BACK; | |
| 95 | |
| 96 /* Check if the edge destination has been visited yet. */ | |
| 111 | 97 if (dest != EXIT_BLOCK_PTR_FOR_FN (cfun) && ! bitmap_bit_p (visited, |
| 98 dest->index)) | |
| 0 | 99 { |
| 100 /* Mark that we have visited the destination. */ | |
| 111 | 101 bitmap_set_bit (visited, dest->index); |
| 0 | 102 |
| 103 pre[dest->index] = prenum++; | |
| 104 if (EDGE_COUNT (dest->succs) > 0) | |
| 105 { | |
| 106 /* Since the DEST node has been visited for the first | |
| 107 time, check its successors. */ | |
| 111 | 108 stack.quick_push (ei_start (dest->succs)); |
| 0 | 109 } |
| 110 else | |
| 111 post[dest->index] = postnum++; | |
| 112 } | |
| 113 else | |
| 114 { | |
| 111 | 115 if (dest != EXIT_BLOCK_PTR_FOR_FN (cfun) |
| 116 && src != ENTRY_BLOCK_PTR_FOR_FN (cfun) | |
| 0 | 117 && pre[src->index] >= pre[dest->index] |
| 118 && post[dest->index] == 0) | |
| 119 ei_edge (ei)->flags |= EDGE_DFS_BACK, found = true; | |
| 120 | |
| 111 | 121 if (ei_one_before_end_p (ei) |
| 122 && src != ENTRY_BLOCK_PTR_FOR_FN (cfun)) | |
| 0 | 123 post[src->index] = postnum++; |
| 124 | |
| 125 if (!ei_one_before_end_p (ei)) | |
| 111 | 126 ei_next (&stack.last ()); |
| 0 | 127 else |
| 111 | 128 stack.pop (); |
| 0 | 129 } |
| 130 } | |
| 131 | |
| 132 free (pre); | |
| 133 free (post); | |
| 134 | |
| 135 return found; | |
| 136 } | |
| 137 | |
| 138 /* Find unreachable blocks. An unreachable block will have 0 in | |
| 139 the reachable bit in block->flags. A nonzero value indicates the | |
| 140 block is reachable. */ | |
| 141 | |
| 142 void | |
| 143 find_unreachable_blocks (void) | |
| 144 { | |
| 145 edge e; | |
| 146 edge_iterator ei; | |
| 147 basic_block *tos, *worklist, bb; | |
| 148 | |
| 111 | 149 tos = worklist = XNEWVEC (basic_block, n_basic_blocks_for_fn (cfun)); |
| 0 | 150 |
| 151 /* Clear all the reachability flags. */ | |
| 152 | |
| 111 | 153 FOR_EACH_BB_FN (bb, cfun) |
| 0 | 154 bb->flags &= ~BB_REACHABLE; |
| 155 | |
| 156 /* Add our starting points to the worklist. Almost always there will | |
| 157 be only one. It isn't inconceivable that we might one day directly | |
| 158 support Fortran alternate entry points. */ | |
| 159 | |
| 111 | 160 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR_FOR_FN (cfun)->succs) |
| 0 | 161 { |
| 162 *tos++ = e->dest; | |
| 163 | |
| 164 /* Mark the block reachable. */ | |
| 165 e->dest->flags |= BB_REACHABLE; | |
| 166 } | |
| 167 | |
| 168 /* Iterate: find everything reachable from what we've already seen. */ | |
| 169 | |
| 170 while (tos != worklist) | |
| 171 { | |
| 172 basic_block b = *--tos; | |
| 173 | |
| 174 FOR_EACH_EDGE (e, ei, b->succs) | |
| 175 { | |
| 176 basic_block dest = e->dest; | |
| 177 | |
| 178 if (!(dest->flags & BB_REACHABLE)) | |
| 179 { | |
| 180 *tos++ = dest; | |
| 181 dest->flags |= BB_REACHABLE; | |
| 182 } | |
| 183 } | |
| 184 } | |
| 185 | |
| 186 free (worklist); | |
| 187 } | |
| 111 | 188 |
| 189 /* Verify that there are no unreachable blocks in the current function. */ | |
| 190 | |
| 191 void | |
| 192 verify_no_unreachable_blocks (void) | |
| 193 { | |
| 194 find_unreachable_blocks (); | |
| 195 | |
| 196 basic_block bb; | |
| 197 FOR_EACH_BB_FN (bb, cfun) | |
| 198 gcc_assert ((bb->flags & BB_REACHABLE) != 0); | |
| 199 } | |
| 200 | |
| 0 | 201 |
| 202 /* Functions to access an edge list with a vector representation. | |
| 203 Enough data is kept such that given an index number, the | |
| 204 pred and succ that edge represents can be determined, or | |
| 205 given a pred and a succ, its index number can be returned. | |
| 206 This allows algorithms which consume a lot of memory to | |
| 207 represent the normally full matrix of edge (pred,succ) with a | |
| 208 single indexed vector, edge (EDGE_INDEX (pred, succ)), with no | |
| 209 wasted space in the client code due to sparse flow graphs. */ | |
| 210 | |
| 211 /* This functions initializes the edge list. Basically the entire | |
| 212 flowgraph is processed, and all edges are assigned a number, | |
| 213 and the data structure is filled in. */ | |
| 214 | |
| 215 struct edge_list * | |
| 216 create_edge_list (void) | |
| 217 { | |
| 218 struct edge_list *elist; | |
| 219 edge e; | |
| 220 int num_edges; | |
| 221 basic_block bb; | |
| 222 edge_iterator ei; | |
| 223 | |
| 224 /* Determine the number of edges in the flow graph by counting successor | |
| 225 edges on each basic block. */ | |
| 111 | 226 num_edges = 0; |
| 227 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR_FOR_FN (cfun), | |
| 228 EXIT_BLOCK_PTR_FOR_FN (cfun), next_bb) | |
| 0 | 229 { |
| 230 num_edges += EDGE_COUNT (bb->succs); | |
| 231 } | |
| 232 | |
| 233 elist = XNEW (struct edge_list); | |
| 234 elist->num_edges = num_edges; | |
| 235 elist->index_to_edge = XNEWVEC (edge, num_edges); | |
| 236 | |
| 237 num_edges = 0; | |
| 238 | |
| 239 /* Follow successors of blocks, and register these edges. */ | |
| 111 | 240 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR_FOR_FN (cfun), |
| 241 EXIT_BLOCK_PTR_FOR_FN (cfun), next_bb) | |
| 0 | 242 FOR_EACH_EDGE (e, ei, bb->succs) |
| 243 elist->index_to_edge[num_edges++] = e; | |
| 244 | |
| 245 return elist; | |
| 246 } | |
| 247 | |
| 248 /* This function free's memory associated with an edge list. */ | |
| 249 | |
| 250 void | |
| 251 free_edge_list (struct edge_list *elist) | |
| 252 { | |
| 253 if (elist) | |
| 254 { | |
| 255 free (elist->index_to_edge); | |
| 256 free (elist); | |
| 257 } | |
| 258 } | |
| 259 | |
| 260 /* This function provides debug output showing an edge list. */ | |
| 261 | |
|
67
f6334be47118
update gcc from gcc-4.6-20100522 to gcc-4.6-20110318
nobuyasu <dimolto@cr.ie.u-ryukyu.ac.jp>
parents:
63
diff
changeset
|
262 DEBUG_FUNCTION void |
| 0 | 263 print_edge_list (FILE *f, struct edge_list *elist) |
| 264 { | |
| 265 int x; | |
| 266 | |
| 267 fprintf (f, "Compressed edge list, %d BBs + entry & exit, and %d edges\n", | |
| 111 | 268 n_basic_blocks_for_fn (cfun), elist->num_edges); |
| 0 | 269 |
| 270 for (x = 0; x < elist->num_edges; x++) | |
| 271 { | |
| 272 fprintf (f, " %-4d - edge(", x); | |
| 111 | 273 if (INDEX_EDGE_PRED_BB (elist, x) == ENTRY_BLOCK_PTR_FOR_FN (cfun)) |
| 0 | 274 fprintf (f, "entry,"); |
| 275 else | |
| 276 fprintf (f, "%d,", INDEX_EDGE_PRED_BB (elist, x)->index); | |
| 277 | |
| 111 | 278 if (INDEX_EDGE_SUCC_BB (elist, x) == EXIT_BLOCK_PTR_FOR_FN (cfun)) |
| 0 | 279 fprintf (f, "exit)\n"); |
| 280 else | |
| 281 fprintf (f, "%d)\n", INDEX_EDGE_SUCC_BB (elist, x)->index); | |
| 282 } | |
| 283 } | |
| 284 | |
| 285 /* This function provides an internal consistency check of an edge list, | |
| 286 verifying that all edges are present, and that there are no | |
| 287 extra edges. */ | |
| 288 | |
|
67
f6334be47118
update gcc from gcc-4.6-20100522 to gcc-4.6-20110318
nobuyasu <dimolto@cr.ie.u-ryukyu.ac.jp>
parents:
63
diff
changeset
|
289 DEBUG_FUNCTION void |
| 0 | 290 verify_edge_list (FILE *f, struct edge_list *elist) |
| 291 { | |
| 292 int pred, succ, index; | |
| 293 edge e; | |
| 294 basic_block bb, p, s; | |
| 295 edge_iterator ei; | |
| 296 | |
| 111 | 297 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR_FOR_FN (cfun), |
| 298 EXIT_BLOCK_PTR_FOR_FN (cfun), next_bb) | |
| 0 | 299 { |
| 300 FOR_EACH_EDGE (e, ei, bb->succs) | |
| 301 { | |
| 302 pred = e->src->index; | |
| 303 succ = e->dest->index; | |
| 304 index = EDGE_INDEX (elist, e->src, e->dest); | |
| 305 if (index == EDGE_INDEX_NO_EDGE) | |
| 306 { | |
| 307 fprintf (f, "*p* No index for edge from %d to %d\n", pred, succ); | |
| 308 continue; | |
| 309 } | |
| 310 | |
| 311 if (INDEX_EDGE_PRED_BB (elist, index)->index != pred) | |
| 312 fprintf (f, "*p* Pred for index %d should be %d not %d\n", | |
| 313 index, pred, INDEX_EDGE_PRED_BB (elist, index)->index); | |
| 314 if (INDEX_EDGE_SUCC_BB (elist, index)->index != succ) | |
| 315 fprintf (f, "*p* Succ for index %d should be %d not %d\n", | |
| 316 index, succ, INDEX_EDGE_SUCC_BB (elist, index)->index); | |
| 317 } | |
| 318 } | |
| 319 | |
| 320 /* We've verified that all the edges are in the list, now lets make sure | |
| 111 | 321 there are no spurious edges in the list. This is an expensive check! */ |
| 0 | 322 |
| 111 | 323 FOR_BB_BETWEEN (p, ENTRY_BLOCK_PTR_FOR_FN (cfun), |
| 324 EXIT_BLOCK_PTR_FOR_FN (cfun), next_bb) | |
| 325 FOR_BB_BETWEEN (s, ENTRY_BLOCK_PTR_FOR_FN (cfun)->next_bb, NULL, next_bb) | |
| 0 | 326 { |
| 327 int found_edge = 0; | |
| 328 | |
| 329 FOR_EACH_EDGE (e, ei, p->succs) | |
| 330 if (e->dest == s) | |
| 331 { | |
| 332 found_edge = 1; | |
| 333 break; | |
| 334 } | |
| 335 | |
| 336 FOR_EACH_EDGE (e, ei, s->preds) | |
| 337 if (e->src == p) | |
| 338 { | |
| 339 found_edge = 1; | |
| 340 break; | |
| 341 } | |
| 342 | |
| 343 if (EDGE_INDEX (elist, p, s) | |
| 344 == EDGE_INDEX_NO_EDGE && found_edge != 0) | |
| 345 fprintf (f, "*** Edge (%d, %d) appears to not have an index\n", | |
| 346 p->index, s->index); | |
| 347 if (EDGE_INDEX (elist, p, s) | |
| 348 != EDGE_INDEX_NO_EDGE && found_edge == 0) | |
| 349 fprintf (f, "*** Edge (%d, %d) has index %d, but there is no edge\n", | |
| 350 p->index, s->index, EDGE_INDEX (elist, p, s)); | |
| 351 } | |
| 352 } | |
| 353 | |
| 111 | 354 |
| 355 /* Functions to compute control dependences. */ | |
| 356 | |
| 357 /* Indicate block BB is control dependent on an edge with index EDGE_INDEX. */ | |
| 358 void | |
| 359 control_dependences::set_control_dependence_map_bit (basic_block bb, | |
| 360 int edge_index) | |
| 361 { | |
| 362 if (bb == ENTRY_BLOCK_PTR_FOR_FN (cfun)) | |
| 363 return; | |
| 364 gcc_assert (bb != EXIT_BLOCK_PTR_FOR_FN (cfun)); | |
| 365 bitmap_set_bit (control_dependence_map[bb->index], edge_index); | |
| 366 } | |
| 367 | |
| 368 /* Clear all control dependences for block BB. */ | |
| 369 void | |
| 370 control_dependences::clear_control_dependence_bitmap (basic_block bb) | |
| 371 { | |
| 372 bitmap_clear (control_dependence_map[bb->index]); | |
| 373 } | |
| 374 | |
| 375 /* Find the immediate postdominator PDOM of the specified basic block BLOCK. | |
| 376 This function is necessary because some blocks have negative numbers. */ | |
| 377 | |
| 378 static inline basic_block | |
| 379 find_pdom (basic_block block) | |
| 380 { | |
| 381 gcc_assert (block != ENTRY_BLOCK_PTR_FOR_FN (cfun)); | |
| 382 | |
| 383 if (block == EXIT_BLOCK_PTR_FOR_FN (cfun)) | |
| 384 return EXIT_BLOCK_PTR_FOR_FN (cfun); | |
| 385 else | |
| 386 { | |
| 387 basic_block bb = get_immediate_dominator (CDI_POST_DOMINATORS, block); | |
| 388 if (! bb) | |
| 389 return EXIT_BLOCK_PTR_FOR_FN (cfun); | |
| 390 return bb; | |
| 391 } | |
| 392 } | |
| 393 | |
| 394 /* Determine all blocks' control dependences on the given edge with edge_list | |
| 395 EL index EDGE_INDEX, ala Morgan, Section 3.6. */ | |
| 396 | |
| 397 void | |
| 398 control_dependences::find_control_dependence (int edge_index) | |
| 399 { | |
| 400 basic_block current_block; | |
| 401 basic_block ending_block; | |
| 402 | |
| 403 gcc_assert (get_edge_src (edge_index) != EXIT_BLOCK_PTR_FOR_FN (cfun)); | |
| 404 | |
| 405 /* For abnormal edges, we don't make current_block control | |
| 406 dependent because instructions that throw are always necessary | |
| 407 anyway. */ | |
| 408 edge e = find_edge (get_edge_src (edge_index), get_edge_dest (edge_index)); | |
| 409 if (e->flags & EDGE_ABNORMAL) | |
| 410 return; | |
| 411 | |
| 412 if (get_edge_src (edge_index) == ENTRY_BLOCK_PTR_FOR_FN (cfun)) | |
| 413 ending_block = single_succ (ENTRY_BLOCK_PTR_FOR_FN (cfun)); | |
| 414 else | |
| 415 ending_block = find_pdom (get_edge_src (edge_index)); | |
| 416 | |
| 417 for (current_block = get_edge_dest (edge_index); | |
| 418 current_block != ending_block | |
| 419 && current_block != EXIT_BLOCK_PTR_FOR_FN (cfun); | |
| 420 current_block = find_pdom (current_block)) | |
| 421 set_control_dependence_map_bit (current_block, edge_index); | |
| 422 } | |
| 423 | |
| 424 /* Record all blocks' control dependences on all edges in the edge | |
| 425 list EL, ala Morgan, Section 3.6. */ | |
| 426 | |
| 427 control_dependences::control_dependences () | |
| 428 { | |
| 429 timevar_push (TV_CONTROL_DEPENDENCES); | |
| 430 | |
| 431 /* Initialize the edge list. */ | |
| 432 int num_edges = 0; | |
| 433 basic_block bb; | |
| 434 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR_FOR_FN (cfun), | |
| 435 EXIT_BLOCK_PTR_FOR_FN (cfun), next_bb) | |
| 436 num_edges += EDGE_COUNT (bb->succs); | |
| 437 m_el.create (num_edges); | |
| 438 edge e; | |
| 439 edge_iterator ei; | |
| 440 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR_FOR_FN (cfun), | |
| 441 EXIT_BLOCK_PTR_FOR_FN (cfun), next_bb) | |
| 442 FOR_EACH_EDGE (e, ei, bb->succs) | |
| 443 m_el.quick_push (std::make_pair (e->src->index, e->dest->index)); | |
| 444 | |
| 445 control_dependence_map.create (last_basic_block_for_fn (cfun)); | |
| 446 for (int i = 0; i < last_basic_block_for_fn (cfun); ++i) | |
| 447 control_dependence_map.quick_push (BITMAP_ALLOC (NULL)); | |
| 448 for (int i = 0; i < num_edges; ++i) | |
| 449 find_control_dependence (i); | |
| 450 | |
| 451 timevar_pop (TV_CONTROL_DEPENDENCES); | |
| 452 } | |
| 453 | |
| 454 /* Free control dependences and the associated edge list. */ | |
| 455 | |
| 456 control_dependences::~control_dependences () | |
| 457 { | |
| 458 for (unsigned i = 0; i < control_dependence_map.length (); ++i) | |
| 459 BITMAP_FREE (control_dependence_map[i]); | |
| 460 control_dependence_map.release (); | |
| 461 m_el.release (); | |
| 462 } | |
| 463 | |
| 464 /* Returns the bitmap of edges the basic-block I is dependent on. */ | |
| 465 | |
| 466 bitmap | |
| 467 control_dependences::get_edges_dependent_on (int i) | |
| 468 { | |
| 469 return control_dependence_map[i]; | |
| 470 } | |
| 471 | |
| 472 /* Returns the edge source with index I from the edge list. */ | |
| 473 | |
| 474 basic_block | |
| 475 control_dependences::get_edge_src (int i) | |
| 476 { | |
| 477 return BASIC_BLOCK_FOR_FN (cfun, m_el[i].first); | |
| 478 } | |
| 479 | |
| 480 /* Returns the edge destination with index I from the edge list. */ | |
| 481 | |
| 482 basic_block | |
| 483 control_dependences::get_edge_dest (int i) | |
| 484 { | |
| 485 return BASIC_BLOCK_FOR_FN (cfun, m_el[i].second); | |
| 486 } | |
| 487 | |
| 488 | |
| 0 | 489 /* Given PRED and SUCC blocks, return the edge which connects the blocks. |
| 490 If no such edge exists, return NULL. */ | |
| 491 | |
| 492 edge | |
| 493 find_edge (basic_block pred, basic_block succ) | |
| 494 { | |
| 495 edge e; | |
| 496 edge_iterator ei; | |
| 497 | |
| 498 if (EDGE_COUNT (pred->succs) <= EDGE_COUNT (succ->preds)) | |
| 499 { | |
| 500 FOR_EACH_EDGE (e, ei, pred->succs) | |
| 501 if (e->dest == succ) | |
| 502 return e; | |
| 503 } | |
| 504 else | |
| 505 { | |
| 506 FOR_EACH_EDGE (e, ei, succ->preds) | |
| 507 if (e->src == pred) | |
| 508 return e; | |
| 509 } | |
| 510 | |
| 511 return NULL; | |
| 512 } | |
| 513 | |
| 514 /* This routine will determine what, if any, edge there is between | |
| 515 a specified predecessor and successor. */ | |
| 516 | |
| 517 int | |
| 518 find_edge_index (struct edge_list *edge_list, basic_block pred, basic_block succ) | |
| 519 { | |
| 520 int x; | |
| 521 | |
| 522 for (x = 0; x < NUM_EDGES (edge_list); x++) | |
| 523 if (INDEX_EDGE_PRED_BB (edge_list, x) == pred | |
| 524 && INDEX_EDGE_SUCC_BB (edge_list, x) == succ) | |
| 525 return x; | |
| 526 | |
| 527 return (EDGE_INDEX_NO_EDGE); | |
| 528 } | |
| 529 | |
| 530 /* This routine will remove any fake predecessor edges for a basic block. | |
| 531 When the edge is removed, it is also removed from whatever successor | |
| 532 list it is in. */ | |
| 533 | |
| 534 static void | |
| 535 remove_fake_predecessors (basic_block bb) | |
| 536 { | |
| 537 edge e; | |
| 538 edge_iterator ei; | |
| 539 | |
| 540 for (ei = ei_start (bb->preds); (e = ei_safe_edge (ei)); ) | |
| 541 { | |
| 542 if ((e->flags & EDGE_FAKE) == EDGE_FAKE) | |
| 543 remove_edge (e); | |
| 544 else | |
| 545 ei_next (&ei); | |
| 546 } | |
| 547 } | |
| 548 | |
| 549 /* This routine will remove all fake edges from the flow graph. If | |
| 550 we remove all fake successors, it will automatically remove all | |
| 551 fake predecessors. */ | |
| 552 | |
| 553 void | |
| 554 remove_fake_edges (void) | |
| 555 { | |
| 556 basic_block bb; | |
| 557 | |
| 111 | 558 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR_FOR_FN (cfun)->next_bb, NULL, next_bb) |
| 0 | 559 remove_fake_predecessors (bb); |
| 560 } | |
| 561 | |
| 562 /* This routine will remove all fake edges to the EXIT_BLOCK. */ | |
| 563 | |
| 564 void | |
| 565 remove_fake_exit_edges (void) | |
| 566 { | |
| 111 | 567 remove_fake_predecessors (EXIT_BLOCK_PTR_FOR_FN (cfun)); |
| 0 | 568 } |
| 569 | |
| 570 | |
| 571 /* This function will add a fake edge between any block which has no | |
| 572 successors, and the exit block. Some data flow equations require these | |
| 573 edges to exist. */ | |
| 574 | |
| 575 void | |
| 576 add_noreturn_fake_exit_edges (void) | |
| 577 { | |
| 578 basic_block bb; | |
| 579 | |
| 111 | 580 FOR_EACH_BB_FN (bb, cfun) |
| 0 | 581 if (EDGE_COUNT (bb->succs) == 0) |
| 111 | 582 make_single_succ_edge (bb, EXIT_BLOCK_PTR_FOR_FN (cfun), EDGE_FAKE); |
| 0 | 583 } |
| 584 | |
| 585 /* This function adds a fake edge between any infinite loops to the | |
| 586 exit block. Some optimizations require a path from each node to | |
| 587 the exit node. | |
| 588 | |
| 589 See also Morgan, Figure 3.10, pp. 82-83. | |
| 590 | |
| 591 The current implementation is ugly, not attempting to minimize the | |
| 592 number of inserted fake edges. To reduce the number of fake edges | |
| 593 to insert, add fake edges from _innermost_ loops containing only | |
| 594 nodes not reachable from the exit block. */ | |
| 595 | |
| 596 void | |
| 597 connect_infinite_loops_to_exit (void) | |
| 598 { | |
| 599 /* Perform depth-first search in the reverse graph to find nodes | |
| 600 reachable from the exit block. */ | |
| 111 | 601 depth_first_search dfs; |
| 602 dfs.add_bb (EXIT_BLOCK_PTR_FOR_FN (cfun)); | |
| 0 | 603 |
| 604 /* Repeatedly add fake edges, updating the unreachable nodes. */ | |
| 111 | 605 basic_block unvisited_block = EXIT_BLOCK_PTR_FOR_FN (cfun); |
| 0 | 606 while (1) |
| 607 { | |
| 111 | 608 unvisited_block = dfs.execute (unvisited_block); |
| 0 | 609 if (!unvisited_block) |
| 610 break; | |
| 611 | |
| 111 | 612 basic_block deadend_block = dfs_find_deadend (unvisited_block); |
| 613 edge e = make_edge (deadend_block, EXIT_BLOCK_PTR_FOR_FN (cfun), | |
| 614 EDGE_FAKE); | |
| 615 e->probability = profile_probability::never (); | |
| 616 dfs.add_bb (deadend_block); | |
| 0 | 617 } |
| 618 } | |
| 619 | |
| 620 /* Compute reverse top sort order. This is computing a post order | |
| 111 | 621 numbering of the graph. If INCLUDE_ENTRY_EXIT is true, then |
| 0 | 622 ENTRY_BLOCK and EXIT_BLOCK are included. If DELETE_UNREACHABLE is |
| 623 true, unreachable blocks are deleted. */ | |
| 624 | |
| 625 int | |
|
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626 post_order_compute (int *post_order, bool include_entry_exit, |
| 0 | 627 bool delete_unreachable) |
| 628 { | |
| 629 int post_order_num = 0; | |
| 630 int count; | |
| 631 | |
| 632 if (include_entry_exit) | |
| 633 post_order[post_order_num++] = EXIT_BLOCK; | |
| 634 | |
| 635 /* Allocate stack for back-tracking up CFG. */ | |
| 111 | 636 auto_vec<edge_iterator, 20> stack (n_basic_blocks_for_fn (cfun) + 1); |
| 0 | 637 |
| 638 /* Allocate bitmap to track nodes that have been visited. */ | |
| 111 | 639 auto_sbitmap visited (last_basic_block_for_fn (cfun)); |
| 0 | 640 |
| 641 /* None of the nodes in the CFG have been visited yet. */ | |
| 111 | 642 bitmap_clear (visited); |
| 0 | 643 |
| 644 /* Push the first edge on to the stack. */ | |
| 111 | 645 stack.quick_push (ei_start (ENTRY_BLOCK_PTR_FOR_FN (cfun)->succs)); |
| 0 | 646 |
| 111 | 647 while (!stack.is_empty ()) |
| 0 | 648 { |
| 649 basic_block src; | |
| 650 basic_block dest; | |
| 651 | |
| 652 /* Look at the edge on the top of the stack. */ | |
| 111 | 653 edge_iterator ei = stack.last (); |
| 0 | 654 src = ei_edge (ei)->src; |
| 655 dest = ei_edge (ei)->dest; | |
| 656 | |
| 657 /* Check if the edge destination has been visited yet. */ | |
| 111 | 658 if (dest != EXIT_BLOCK_PTR_FOR_FN (cfun) |
| 659 && ! bitmap_bit_p (visited, dest->index)) | |
| 0 | 660 { |
| 661 /* Mark that we have visited the destination. */ | |
| 111 | 662 bitmap_set_bit (visited, dest->index); |
| 0 | 663 |
| 664 if (EDGE_COUNT (dest->succs) > 0) | |
| 665 /* Since the DEST node has been visited for the first | |
| 666 time, check its successors. */ | |
| 111 | 667 stack.quick_push (ei_start (dest->succs)); |
| 0 | 668 else |
| 669 post_order[post_order_num++] = dest->index; | |
| 670 } | |
| 671 else | |
| 672 { | |
| 111 | 673 if (ei_one_before_end_p (ei) |
| 674 && src != ENTRY_BLOCK_PTR_FOR_FN (cfun)) | |
| 0 | 675 post_order[post_order_num++] = src->index; |
| 676 | |
| 677 if (!ei_one_before_end_p (ei)) | |
| 111 | 678 ei_next (&stack.last ()); |
| 0 | 679 else |
| 111 | 680 stack.pop (); |
| 0 | 681 } |
| 682 } | |
| 683 | |
| 684 if (include_entry_exit) | |
| 685 { | |
| 686 post_order[post_order_num++] = ENTRY_BLOCK; | |
| 687 count = post_order_num; | |
| 688 } | |
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689 else |
| 0 | 690 count = post_order_num + 2; |
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691 |
| 0 | 692 /* Delete the unreachable blocks if some were found and we are |
| 693 supposed to do it. */ | |
| 111 | 694 if (delete_unreachable && (count != n_basic_blocks_for_fn (cfun))) |
| 0 | 695 { |
| 696 basic_block b; | |
| 697 basic_block next_bb; | |
| 111 | 698 for (b = ENTRY_BLOCK_PTR_FOR_FN (cfun)->next_bb; b |
| 699 != EXIT_BLOCK_PTR_FOR_FN (cfun); b = next_bb) | |
| 0 | 700 { |
| 701 next_bb = b->next_bb; | |
|
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702 |
| 111 | 703 if (!(bitmap_bit_p (visited, b->index))) |
| 0 | 704 delete_basic_block (b); |
| 705 } | |
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706 |
| 0 | 707 tidy_fallthru_edges (); |
| 708 } | |
| 709 | |
| 710 return post_order_num; | |
| 711 } | |
| 712 | |
| 713 | |
| 111 | 714 /* Helper routine for inverted_post_order_compute |
| 715 flow_dfs_compute_reverse_execute, and the reverse-CFG | |
| 716 deapth first search in dominance.c. | |
| 0 | 717 BB has to belong to a region of CFG |
| 718 unreachable by inverted traversal from the exit. | |
| 719 i.e. there's no control flow path from ENTRY to EXIT | |
| 720 that contains this BB. | |
| 721 This can happen in two cases - if there's an infinite loop | |
| 722 or if there's a block that has no successor | |
| 723 (call to a function with no return). | |
|
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724 Some RTL passes deal with this condition by |
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725 calling connect_infinite_loops_to_exit () and/or |
| 0 | 726 add_noreturn_fake_exit_edges (). |
| 727 However, those methods involve modifying the CFG itself | |
| 728 which may not be desirable. | |
| 729 Hence, we deal with the infinite loop/no return cases | |
| 730 by identifying a unique basic block that can reach all blocks | |
| 731 in such a region by inverted traversal. | |
| 732 This function returns a basic block that guarantees | |
| 733 that all blocks in the region are reachable | |
| 734 by starting an inverted traversal from the returned block. */ | |
| 735 | |
| 111 | 736 basic_block |
| 0 | 737 dfs_find_deadend (basic_block bb) |
| 738 { | |
| 111 | 739 auto_bitmap visited; |
| 740 basic_block next = bb; | |
| 0 | 741 |
| 742 for (;;) | |
| 743 { | |
| 111 | 744 if (EDGE_COUNT (next->succs) == 0) |
| 745 return next; | |
| 746 | |
| 747 if (! bitmap_set_bit (visited, next->index)) | |
| 748 return bb; | |
| 0 | 749 |
| 111 | 750 bb = next; |
| 751 /* If we are in an analyzed cycle make sure to try exiting it. | |
| 752 Note this is a heuristic only and expected to work when loop | |
| 753 fixup is needed as well. */ | |
| 754 if (! bb->loop_father | |
| 755 || ! loop_outer (bb->loop_father)) | |
| 756 next = EDGE_SUCC (bb, 0)->dest; | |
| 757 else | |
| 758 { | |
| 759 edge_iterator ei; | |
| 760 edge e; | |
| 761 FOR_EACH_EDGE (e, ei, bb->succs) | |
| 762 if (loop_exit_edge_p (bb->loop_father, e)) | |
| 763 break; | |
| 764 next = e ? e->dest : EDGE_SUCC (bb, 0)->dest; | |
| 765 } | |
| 0 | 766 } |
| 767 | |
| 768 gcc_unreachable (); | |
| 769 } | |
| 770 | |
| 771 | |
| 772 /* Compute the reverse top sort order of the inverted CFG | |
| 773 i.e. starting from the exit block and following the edges backward | |
| 774 (from successors to predecessors). | |
| 775 This ordering can be used for forward dataflow problems among others. | |
| 776 | |
| 111 | 777 Optionally if START_POINTS is specified, start from exit block and all |
| 778 basic blocks in START_POINTS. This is used by CD-DCE. | |
| 779 | |
| 0 | 780 This function assumes that all blocks in the CFG are reachable |
| 781 from the ENTRY (but not necessarily from EXIT). | |
| 782 | |
| 783 If there's an infinite loop, | |
| 784 a simple inverted traversal starting from the blocks | |
| 785 with no successors can't visit all blocks. | |
| 786 To solve this problem, we first do inverted traversal | |
| 787 starting from the blocks with no successor. | |
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788 And if there's any block left that's not visited by the regular |
| 0 | 789 inverted traversal from EXIT, |
| 790 those blocks are in such problematic region. | |
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791 Among those, we find one block that has |
| 0 | 792 any visited predecessor (which is an entry into such a region), |
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793 and start looking for a "dead end" from that block |
| 0 | 794 and do another inverted traversal from that block. */ |
| 795 | |
| 111 | 796 void |
| 797 inverted_post_order_compute (vec<int> *post_order, | |
| 798 sbitmap *start_points) | |
| 0 | 799 { |
| 800 basic_block bb; | |
| 111 | 801 post_order->reserve_exact (n_basic_blocks_for_fn (cfun)); |
| 802 | |
| 803 if (flag_checking) | |
| 804 verify_no_unreachable_blocks (); | |
| 0 | 805 |
| 806 /* Allocate stack for back-tracking up CFG. */ | |
| 111 | 807 auto_vec<edge_iterator, 20> stack (n_basic_blocks_for_fn (cfun) + 1); |
| 0 | 808 |
| 809 /* Allocate bitmap to track nodes that have been visited. */ | |
| 111 | 810 auto_sbitmap visited (last_basic_block_for_fn (cfun)); |
| 0 | 811 |
| 812 /* None of the nodes in the CFG have been visited yet. */ | |
| 111 | 813 bitmap_clear (visited); |
| 0 | 814 |
| 111 | 815 if (start_points) |
| 816 { | |
| 817 FOR_ALL_BB_FN (bb, cfun) | |
| 818 if (bitmap_bit_p (*start_points, bb->index) | |
| 819 && EDGE_COUNT (bb->preds) > 0) | |
| 820 { | |
| 821 stack.quick_push (ei_start (bb->preds)); | |
| 822 bitmap_set_bit (visited, bb->index); | |
| 823 } | |
| 824 if (EDGE_COUNT (EXIT_BLOCK_PTR_FOR_FN (cfun)->preds)) | |
| 825 { | |
| 826 stack.quick_push (ei_start (EXIT_BLOCK_PTR_FOR_FN (cfun)->preds)); | |
| 827 bitmap_set_bit (visited, EXIT_BLOCK_PTR_FOR_FN (cfun)->index); | |
| 828 } | |
| 829 } | |
| 830 else | |
| 0 | 831 /* Put all blocks that have no successor into the initial work list. */ |
| 111 | 832 FOR_ALL_BB_FN (bb, cfun) |
| 0 | 833 if (EDGE_COUNT (bb->succs) == 0) |
| 834 { | |
| 835 /* Push the initial edge on to the stack. */ | |
|
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836 if (EDGE_COUNT (bb->preds) > 0) |
| 0 | 837 { |
| 111 | 838 stack.quick_push (ei_start (bb->preds)); |
| 839 bitmap_set_bit (visited, bb->index); | |
| 0 | 840 } |
| 841 } | |
| 842 | |
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843 do |
| 0 | 844 { |
| 845 bool has_unvisited_bb = false; | |
| 846 | |
| 847 /* The inverted traversal loop. */ | |
| 111 | 848 while (!stack.is_empty ()) |
| 0 | 849 { |
| 850 edge_iterator ei; | |
| 851 basic_block pred; | |
| 852 | |
| 853 /* Look at the edge on the top of the stack. */ | |
| 111 | 854 ei = stack.last (); |
| 0 | 855 bb = ei_edge (ei)->dest; |
| 856 pred = ei_edge (ei)->src; | |
| 857 | |
| 858 /* Check if the predecessor has been visited yet. */ | |
| 111 | 859 if (! bitmap_bit_p (visited, pred->index)) |
| 0 | 860 { |
| 861 /* Mark that we have visited the destination. */ | |
| 111 | 862 bitmap_set_bit (visited, pred->index); |
| 0 | 863 |
| 864 if (EDGE_COUNT (pred->preds) > 0) | |
| 865 /* Since the predecessor node has been visited for the first | |
| 866 time, check its predecessors. */ | |
| 111 | 867 stack.quick_push (ei_start (pred->preds)); |
| 0 | 868 else |
| 111 | 869 post_order->quick_push (pred->index); |
| 0 | 870 } |
| 871 else | |
| 872 { | |
| 111 | 873 if (bb != EXIT_BLOCK_PTR_FOR_FN (cfun) |
| 874 && ei_one_before_end_p (ei)) | |
| 875 post_order->quick_push (bb->index); | |
| 0 | 876 |
| 877 if (!ei_one_before_end_p (ei)) | |
| 111 | 878 ei_next (&stack.last ()); |
| 0 | 879 else |
| 111 | 880 stack.pop (); |
| 0 | 881 } |
| 882 } | |
| 883 | |
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884 /* Detect any infinite loop and activate the kludge. |
| 0 | 885 Note that this doesn't check EXIT_BLOCK itself |
| 111 | 886 since EXIT_BLOCK is always added after the outer do-while loop. */ |
| 887 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR_FOR_FN (cfun), | |
| 888 EXIT_BLOCK_PTR_FOR_FN (cfun), next_bb) | |
| 889 if (!bitmap_bit_p (visited, bb->index)) | |
| 0 | 890 { |
| 891 has_unvisited_bb = true; | |
| 892 | |
| 893 if (EDGE_COUNT (bb->preds) > 0) | |
| 894 { | |
| 895 edge_iterator ei; | |
| 896 edge e; | |
| 897 basic_block visited_pred = NULL; | |
| 898 | |
| 899 /* Find an already visited predecessor. */ | |
| 900 FOR_EACH_EDGE (e, ei, bb->preds) | |
| 901 { | |
| 111 | 902 if (bitmap_bit_p (visited, e->src->index)) |
| 0 | 903 visited_pred = e->src; |
| 904 } | |
| 905 | |
| 906 if (visited_pred) | |
| 907 { | |
| 908 basic_block be = dfs_find_deadend (bb); | |
| 909 gcc_assert (be != NULL); | |
| 111 | 910 bitmap_set_bit (visited, be->index); |
| 911 stack.quick_push (ei_start (be->preds)); | |
| 0 | 912 break; |
| 913 } | |
| 914 } | |
| 915 } | |
| 916 | |
| 111 | 917 if (has_unvisited_bb && stack.is_empty ()) |
| 0 | 918 { |
| 111 | 919 /* No blocks are reachable from EXIT at all. |
| 0 | 920 Find a dead-end from the ENTRY, and restart the iteration. */ |
| 111 | 921 basic_block be = dfs_find_deadend (ENTRY_BLOCK_PTR_FOR_FN (cfun)); |
| 0 | 922 gcc_assert (be != NULL); |
| 111 | 923 bitmap_set_bit (visited, be->index); |
| 924 stack.quick_push (ei_start (be->preds)); | |
| 0 | 925 } |
| 926 | |
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927 /* The only case the below while fires is |
| 0 | 928 when there's an infinite loop. */ |
| 929 } | |
| 111 | 930 while (!stack.is_empty ()); |
| 0 | 931 |
| 932 /* EXIT_BLOCK is always included. */ | |
| 111 | 933 post_order->quick_push (EXIT_BLOCK); |
| 0 | 934 } |
| 935 | |
| 111 | 936 /* Compute the depth first search order of FN and store in the array |
| 937 PRE_ORDER if nonzero. If REV_POST_ORDER is nonzero, return the | |
| 938 reverse completion number for each node. Returns the number of nodes | |
| 939 visited. A depth first search tries to get as far away from the starting | |
| 940 point as quickly as possible. | |
| 0 | 941 |
| 111 | 942 In case the function has unreachable blocks the number of nodes |
| 943 visited does not include them. | |
| 944 | |
| 945 pre_order is a really a preorder numbering of the graph. | |
| 946 rev_post_order is really a reverse postorder numbering of the graph. */ | |
| 0 | 947 |
| 948 int | |
| 111 | 949 pre_and_rev_post_order_compute_fn (struct function *fn, |
| 950 int *pre_order, int *rev_post_order, | |
| 951 bool include_entry_exit) | |
| 0 | 952 { |
| 953 int pre_order_num = 0; | |
| 111 | 954 int rev_post_order_num = n_basic_blocks_for_fn (cfun) - 1; |
| 0 | 955 |
| 956 /* Allocate stack for back-tracking up CFG. */ | |
| 111 | 957 auto_vec<edge_iterator, 20> stack (n_basic_blocks_for_fn (cfun) + 1); |
| 0 | 958 |
| 959 if (include_entry_exit) | |
| 960 { | |
| 961 if (pre_order) | |
| 962 pre_order[pre_order_num] = ENTRY_BLOCK; | |
| 963 pre_order_num++; | |
| 964 if (rev_post_order) | |
| 111 | 965 rev_post_order[rev_post_order_num--] = EXIT_BLOCK; |
| 0 | 966 } |
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967 else |
| 0 | 968 rev_post_order_num -= NUM_FIXED_BLOCKS; |
| 969 | |
| 970 /* Allocate bitmap to track nodes that have been visited. */ | |
| 111 | 971 auto_sbitmap visited (last_basic_block_for_fn (cfun)); |
| 0 | 972 |
| 973 /* None of the nodes in the CFG have been visited yet. */ | |
| 111 | 974 bitmap_clear (visited); |
| 0 | 975 |
| 976 /* Push the first edge on to the stack. */ | |
| 111 | 977 stack.quick_push (ei_start (ENTRY_BLOCK_PTR_FOR_FN (fn)->succs)); |
| 0 | 978 |
| 111 | 979 while (!stack.is_empty ()) |
| 0 | 980 { |
| 981 basic_block src; | |
| 982 basic_block dest; | |
| 983 | |
| 984 /* Look at the edge on the top of the stack. */ | |
| 111 | 985 edge_iterator ei = stack.last (); |
| 0 | 986 src = ei_edge (ei)->src; |
| 987 dest = ei_edge (ei)->dest; | |
| 988 | |
| 989 /* Check if the edge destination has been visited yet. */ | |
| 111 | 990 if (dest != EXIT_BLOCK_PTR_FOR_FN (fn) |
| 991 && ! bitmap_bit_p (visited, dest->index)) | |
| 0 | 992 { |
| 993 /* Mark that we have visited the destination. */ | |
| 111 | 994 bitmap_set_bit (visited, dest->index); |
| 0 | 995 |
| 996 if (pre_order) | |
| 997 pre_order[pre_order_num] = dest->index; | |
| 998 | |
| 999 pre_order_num++; | |
| 1000 | |
| 1001 if (EDGE_COUNT (dest->succs) > 0) | |
| 1002 /* Since the DEST node has been visited for the first | |
| 1003 time, check its successors. */ | |
| 111 | 1004 stack.quick_push (ei_start (dest->succs)); |
| 0 | 1005 else if (rev_post_order) |
| 1006 /* There are no successors for the DEST node so assign | |
| 1007 its reverse completion number. */ | |
| 1008 rev_post_order[rev_post_order_num--] = dest->index; | |
| 1009 } | |
| 1010 else | |
| 1011 { | |
| 111 | 1012 if (ei_one_before_end_p (ei) |
| 1013 && src != ENTRY_BLOCK_PTR_FOR_FN (fn) | |
| 0 | 1014 && rev_post_order) |
| 1015 /* There are no more successors for the SRC node | |
| 1016 so assign its reverse completion number. */ | |
| 1017 rev_post_order[rev_post_order_num--] = src->index; | |
| 1018 | |
| 1019 if (!ei_one_before_end_p (ei)) | |
| 111 | 1020 ei_next (&stack.last ()); |
| 0 | 1021 else |
| 111 | 1022 stack.pop (); |
| 0 | 1023 } |
| 1024 } | |
| 1025 | |
| 1026 if (include_entry_exit) | |
| 1027 { | |
| 1028 if (pre_order) | |
| 1029 pre_order[pre_order_num] = EXIT_BLOCK; | |
| 1030 pre_order_num++; | |
| 1031 if (rev_post_order) | |
| 111 | 1032 rev_post_order[rev_post_order_num--] = ENTRY_BLOCK; |
| 0 | 1033 } |
| 111 | 1034 |
| 1035 return pre_order_num; | |
| 1036 } | |
| 1037 | |
| 1038 /* Like pre_and_rev_post_order_compute_fn but operating on the | |
| 1039 current function and asserting that all nodes were visited. */ | |
| 1040 | |
| 1041 int | |
| 1042 pre_and_rev_post_order_compute (int *pre_order, int *rev_post_order, | |
| 1043 bool include_entry_exit) | |
| 1044 { | |
| 1045 int pre_order_num | |
| 1046 = pre_and_rev_post_order_compute_fn (cfun, pre_order, rev_post_order, | |
| 1047 include_entry_exit); | |
| 1048 if (include_entry_exit) | |
| 1049 /* The number of nodes visited should be the number of blocks. */ | |
| 1050 gcc_assert (pre_order_num == n_basic_blocks_for_fn (cfun)); | |
| 0 | 1051 else |
| 1052 /* The number of nodes visited should be the number of blocks minus | |
| 1053 the entry and exit blocks which are not visited here. */ | |
| 111 | 1054 gcc_assert (pre_order_num |
| 1055 == (n_basic_blocks_for_fn (cfun) - NUM_FIXED_BLOCKS)); | |
| 0 | 1056 |
| 1057 return pre_order_num; | |
| 1058 } | |
| 1059 | |
| 1060 /* Compute the depth first search order on the _reverse_ graph and | |
| 1061 store in the array DFS_ORDER, marking the nodes visited in VISITED. | |
| 1062 Returns the number of nodes visited. | |
| 1063 | |
| 1064 The computation is split into three pieces: | |
| 1065 | |
| 1066 flow_dfs_compute_reverse_init () creates the necessary data | |
| 1067 structures. | |
| 1068 | |
| 1069 flow_dfs_compute_reverse_add_bb () adds a basic block to the data | |
| 1070 structures. The block will start the search. | |
| 1071 | |
| 1072 flow_dfs_compute_reverse_execute () continues (or starts) the | |
| 1073 search using the block on the top of the stack, stopping when the | |
| 1074 stack is empty. | |
| 1075 | |
| 1076 flow_dfs_compute_reverse_finish () destroys the necessary data | |
| 1077 structures. | |
| 1078 | |
| 1079 Thus, the user will probably call ..._init(), call ..._add_bb() to | |
| 1080 add a beginning basic block to the stack, call ..._execute(), | |
| 1081 possibly add another bb to the stack and again call ..._execute(), | |
| 1082 ..., and finally call _finish(). */ | |
| 1083 | |
| 1084 /* Initialize the data structures used for depth-first search on the | |
| 1085 reverse graph. If INITIALIZE_STACK is nonzero, the exit block is | |
| 1086 added to the basic block stack. DATA is the current depth-first | |
| 1087 search context. If INITIALIZE_STACK is nonzero, there is an | |
| 1088 element on the stack. */ | |
| 1089 | |
| 111 | 1090 depth_first_search::depth_first_search () : |
| 1091 m_stack (n_basic_blocks_for_fn (cfun)), | |
| 1092 m_visited_blocks (last_basic_block_for_fn (cfun)) | |
| 0 | 1093 { |
| 111 | 1094 bitmap_clear (m_visited_blocks); |
| 0 | 1095 } |
| 1096 | |
| 1097 /* Add the specified basic block to the top of the dfs data | |
| 1098 structures. When the search continues, it will start at the | |
| 1099 block. */ | |
| 1100 | |
| 111 | 1101 void |
| 1102 depth_first_search::add_bb (basic_block bb) | |
| 0 | 1103 { |
| 111 | 1104 m_stack.quick_push (bb); |
| 1105 bitmap_set_bit (m_visited_blocks, bb->index); | |
| 0 | 1106 } |
| 1107 | |
| 1108 /* Continue the depth-first search through the reverse graph starting with the | |
| 1109 block at the stack's top and ending when the stack is empty. Visited nodes | |
| 1110 are marked. Returns an unvisited basic block, or NULL if there is none | |
| 1111 available. */ | |
| 1112 | |
| 111 | 1113 basic_block |
| 1114 depth_first_search::execute (basic_block last_unvisited) | |
| 0 | 1115 { |
| 1116 basic_block bb; | |
| 1117 edge e; | |
| 1118 edge_iterator ei; | |
| 1119 | |
| 111 | 1120 while (!m_stack.is_empty ()) |
| 0 | 1121 { |
| 111 | 1122 bb = m_stack.pop (); |
| 0 | 1123 |
| 1124 /* Perform depth-first search on adjacent vertices. */ | |
| 1125 FOR_EACH_EDGE (e, ei, bb->preds) | |
| 111 | 1126 if (!bitmap_bit_p (m_visited_blocks, e->src->index)) |
| 1127 add_bb (e->src); | |
| 0 | 1128 } |
| 1129 | |
| 1130 /* Determine if there are unvisited basic blocks. */ | |
| 1131 FOR_BB_BETWEEN (bb, last_unvisited, NULL, prev_bb) | |
| 111 | 1132 if (!bitmap_bit_p (m_visited_blocks, bb->index)) |
| 0 | 1133 return bb; |
| 1134 | |
| 1135 return NULL; | |
| 1136 } | |
| 1137 | |
| 1138 /* Performs dfs search from BB over vertices satisfying PREDICATE; | |
| 1139 if REVERSE, go against direction of edges. Returns number of blocks | |
| 1140 found and their list in RSLT. RSLT can contain at most RSLT_MAX items. */ | |
| 1141 int | |
| 1142 dfs_enumerate_from (basic_block bb, int reverse, | |
| 1143 bool (*predicate) (const_basic_block, const void *), | |
| 1144 basic_block *rslt, int rslt_max, const void *data) | |
| 1145 { | |
| 1146 basic_block *st, lbb; | |
| 1147 int sp = 0, tv = 0; | |
| 1148 unsigned size; | |
| 1149 | |
| 1150 /* A bitmap to keep track of visited blocks. Allocating it each time | |
| 1151 this function is called is not possible, since dfs_enumerate_from | |
| 1152 is often used on small (almost) disjoint parts of cfg (bodies of | |
| 1153 loops), and allocating a large sbitmap would lead to quadratic | |
| 1154 behavior. */ | |
| 1155 static sbitmap visited; | |
| 1156 static unsigned v_size; | |
| 1157 | |
| 111 | 1158 #define MARK_VISITED(BB) (bitmap_set_bit (visited, (BB)->index)) |
| 1159 #define UNMARK_VISITED(BB) (bitmap_clear_bit (visited, (BB)->index)) | |
| 1160 #define VISITED_P(BB) (bitmap_bit_p (visited, (BB)->index)) | |
| 0 | 1161 |
| 1162 /* Resize the VISITED sbitmap if necessary. */ | |
| 111 | 1163 size = last_basic_block_for_fn (cfun); |
| 0 | 1164 if (size < 10) |
| 1165 size = 10; | |
| 1166 | |
| 1167 if (!visited) | |
| 1168 { | |
| 1169 | |
| 1170 visited = sbitmap_alloc (size); | |
| 111 | 1171 bitmap_clear (visited); |
| 0 | 1172 v_size = size; |
| 1173 } | |
| 1174 else if (v_size < size) | |
| 1175 { | |
| 1176 /* Ensure that we increase the size of the sbitmap exponentially. */ | |
| 1177 if (2 * v_size > size) | |
| 1178 size = 2 * v_size; | |
| 1179 | |
| 1180 visited = sbitmap_resize (visited, size, 0); | |
| 1181 v_size = size; | |
| 1182 } | |
| 1183 | |
| 111 | 1184 st = XNEWVEC (basic_block, rslt_max); |
| 0 | 1185 rslt[tv++] = st[sp++] = bb; |
| 1186 MARK_VISITED (bb); | |
| 1187 while (sp) | |
| 1188 { | |
| 1189 edge e; | |
| 1190 edge_iterator ei; | |
| 1191 lbb = st[--sp]; | |
| 1192 if (reverse) | |
| 1193 { | |
| 1194 FOR_EACH_EDGE (e, ei, lbb->preds) | |
| 1195 if (!VISITED_P (e->src) && predicate (e->src, data)) | |
| 1196 { | |
| 1197 gcc_assert (tv != rslt_max); | |
| 1198 rslt[tv++] = st[sp++] = e->src; | |
| 1199 MARK_VISITED (e->src); | |
| 1200 } | |
| 1201 } | |
| 1202 else | |
| 1203 { | |
| 1204 FOR_EACH_EDGE (e, ei, lbb->succs) | |
| 1205 if (!VISITED_P (e->dest) && predicate (e->dest, data)) | |
| 1206 { | |
| 1207 gcc_assert (tv != rslt_max); | |
| 1208 rslt[tv++] = st[sp++] = e->dest; | |
| 1209 MARK_VISITED (e->dest); | |
| 1210 } | |
| 1211 } | |
| 1212 } | |
| 1213 free (st); | |
| 1214 for (sp = 0; sp < tv; sp++) | |
| 1215 UNMARK_VISITED (rslt[sp]); | |
| 1216 return tv; | |
| 1217 #undef MARK_VISITED | |
| 1218 #undef UNMARK_VISITED | |
| 1219 #undef VISITED_P | |
| 1220 } | |
| 1221 | |
| 1222 | |
| 1223 /* Compute dominance frontiers, ala Harvey, Ferrante, et al. | |
| 1224 | |
| 1225 This algorithm can be found in Timothy Harvey's PhD thesis, at | |
| 1226 http://www.cs.rice.edu/~harv/dissertation.pdf in the section on iterative | |
| 1227 dominance algorithms. | |
| 1228 | |
| 1229 First, we identify each join point, j (any node with more than one | |
| 1230 incoming edge is a join point). | |
| 1231 | |
| 1232 We then examine each predecessor, p, of j and walk up the dominator tree | |
| 1233 starting at p. | |
| 1234 | |
| 1235 We stop the walk when we reach j's immediate dominator - j is in the | |
| 1236 dominance frontier of each of the nodes in the walk, except for j's | |
| 1237 immediate dominator. Intuitively, all of the rest of j's dominators are | |
| 1238 shared by j's predecessors as well. | |
| 1239 Since they dominate j, they will not have j in their dominance frontiers. | |
| 1240 | |
| 1241 The number of nodes touched by this algorithm is equal to the size | |
| 1242 of the dominance frontiers, no more, no less. | |
| 1243 */ | |
| 1244 | |
| 1245 | |
| 1246 static void | |
|
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1247 compute_dominance_frontiers_1 (bitmap_head *frontiers) |
| 0 | 1248 { |
| 1249 edge p; | |
| 1250 edge_iterator ei; | |
| 1251 basic_block b; | |
| 111 | 1252 FOR_EACH_BB_FN (b, cfun) |
| 0 | 1253 { |
| 1254 if (EDGE_COUNT (b->preds) >= 2) | |
| 1255 { | |
| 1256 FOR_EACH_EDGE (p, ei, b->preds) | |
| 1257 { | |
| 1258 basic_block runner = p->src; | |
| 1259 basic_block domsb; | |
| 111 | 1260 if (runner == ENTRY_BLOCK_PTR_FOR_FN (cfun)) |
| 0 | 1261 continue; |
| 1262 | |
| 1263 domsb = get_immediate_dominator (CDI_DOMINATORS, b); | |
| 1264 while (runner != domsb) | |
| 1265 { | |
|
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|
1266 if (!bitmap_set_bit (&frontiers[runner->index], |
|
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parents:
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|
1267 b->index)) |
| 0 | 1268 break; |
| 1269 runner = get_immediate_dominator (CDI_DOMINATORS, | |
| 1270 runner); | |
| 1271 } | |
| 1272 } | |
| 1273 } | |
| 1274 } | |
| 1275 } | |
| 1276 | |
| 1277 | |
| 1278 void | |
|
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|
1279 compute_dominance_frontiers (bitmap_head *frontiers) |
| 0 | 1280 { |
| 1281 timevar_push (TV_DOM_FRONTIERS); | |
| 1282 | |
| 1283 compute_dominance_frontiers_1 (frontiers); | |
| 1284 | |
| 1285 timevar_pop (TV_DOM_FRONTIERS); | |
| 1286 } | |
| 1287 | |
| 1288 /* Given a set of blocks with variable definitions (DEF_BLOCKS), | |
| 1289 return a bitmap with all the blocks in the iterated dominance | |
| 1290 frontier of the blocks in DEF_BLOCKS. DFS contains dominance | |
| 1291 frontier information as returned by compute_dominance_frontiers. | |
| 1292 | |
| 1293 The resulting set of blocks are the potential sites where PHI nodes | |
| 1294 are needed. The caller is responsible for freeing the memory | |
| 1295 allocated for the return value. */ | |
| 1296 | |
| 1297 bitmap | |
|
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|
1298 compute_idf (bitmap def_blocks, bitmap_head *dfs) |
| 0 | 1299 { |
| 1300 bitmap_iterator bi; | |
| 1301 unsigned bb_index, i; | |
| 1302 bitmap phi_insertion_points; | |
| 1303 | |
| 111 | 1304 /* Each block can appear at most twice on the work-stack. */ |
| 1305 auto_vec<int> work_stack (2 * n_basic_blocks_for_fn (cfun)); | |
| 0 | 1306 phi_insertion_points = BITMAP_ALLOC (NULL); |
| 1307 | |
| 1308 /* Seed the work list with all the blocks in DEF_BLOCKS. We use | |
| 111 | 1309 vec::quick_push here for speed. This is safe because we know that |
| 0 | 1310 the number of definition blocks is no greater than the number of |
| 1311 basic blocks, which is the initial capacity of WORK_STACK. */ | |
| 1312 EXECUTE_IF_SET_IN_BITMAP (def_blocks, 0, bb_index, bi) | |
| 111 | 1313 work_stack.quick_push (bb_index); |
| 0 | 1314 |
| 1315 /* Pop a block off the worklist, add every block that appears in | |
| 1316 the original block's DF that we have not already processed to | |
| 1317 the worklist. Iterate until the worklist is empty. Blocks | |
| 1318 which are added to the worklist are potential sites for | |
| 1319 PHI nodes. */ | |
| 111 | 1320 while (work_stack.length () > 0) |
| 0 | 1321 { |
| 111 | 1322 bb_index = work_stack.pop (); |
| 0 | 1323 |
| 1324 /* Since the registration of NEW -> OLD name mappings is done | |
| 1325 separately from the call to update_ssa, when updating the SSA | |
| 1326 form, the basic blocks where new and/or old names are defined | |
| 1327 may have disappeared by CFG cleanup calls. In this case, | |
| 1328 we may pull a non-existing block from the work stack. */ | |
| 111 | 1329 gcc_checking_assert (bb_index |
| 1330 < (unsigned) last_basic_block_for_fn (cfun)); | |
| 0 | 1331 |
|
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|
1332 EXECUTE_IF_AND_COMPL_IN_BITMAP (&dfs[bb_index], phi_insertion_points, |
| 0 | 1333 0, i, bi) |
| 1334 { | |
| 111 | 1335 work_stack.quick_push (i); |
| 0 | 1336 bitmap_set_bit (phi_insertion_points, i); |
| 1337 } | |
| 1338 } | |
| 1339 | |
| 1340 return phi_insertion_points; | |
| 1341 } | |
| 1342 | |
| 111 | 1343 /* Intersection and union of preds/succs for sbitmap based data flow |
| 1344 solvers. All four functions defined below take the same arguments: | |
| 1345 B is the basic block to perform the operation for. DST is the | |
| 1346 target sbitmap, i.e. the result. SRC is an sbitmap vector of size | |
| 1347 last_basic_block so that it can be indexed with basic block indices. | |
| 1348 DST may be (but does not have to be) SRC[B->index]. */ | |
| 0 | 1349 |
| 111 | 1350 /* Set the bitmap DST to the intersection of SRC of successors of |
| 1351 basic block B. */ | |
| 1352 | |
| 1353 void | |
| 1354 bitmap_intersection_of_succs (sbitmap dst, sbitmap *src, basic_block b) | |
| 1355 { | |
| 1356 unsigned int set_size = dst->size; | |
| 1357 edge e; | |
| 1358 unsigned ix; | |
| 1359 | |
| 1360 for (e = NULL, ix = 0; ix < EDGE_COUNT (b->succs); ix++) | |
| 1361 { | |
| 1362 e = EDGE_SUCC (b, ix); | |
| 1363 if (e->dest == EXIT_BLOCK_PTR_FOR_FN (cfun)) | |
| 1364 continue; | |
| 1365 | |
| 1366 bitmap_copy (dst, src[e->dest->index]); | |
| 1367 break; | |
| 1368 } | |
| 1369 | |
| 1370 if (e == 0) | |
| 1371 bitmap_ones (dst); | |
| 1372 else | |
| 1373 for (++ix; ix < EDGE_COUNT (b->succs); ix++) | |
| 1374 { | |
| 1375 unsigned int i; | |
| 1376 SBITMAP_ELT_TYPE *p, *r; | |
| 1377 | |
| 1378 e = EDGE_SUCC (b, ix); | |
| 1379 if (e->dest == EXIT_BLOCK_PTR_FOR_FN (cfun)) | |
| 1380 continue; | |
| 1381 | |
| 1382 p = src[e->dest->index]->elms; | |
| 1383 r = dst->elms; | |
| 1384 for (i = 0; i < set_size; i++) | |
| 1385 *r++ &= *p++; | |
| 1386 } | |
| 1387 } | |
| 1388 | |
| 1389 /* Set the bitmap DST to the intersection of SRC of predecessors of | |
| 1390 basic block B. */ | |
| 1391 | |
| 1392 void | |
| 1393 bitmap_intersection_of_preds (sbitmap dst, sbitmap *src, basic_block b) | |
| 1394 { | |
| 1395 unsigned int set_size = dst->size; | |
| 1396 edge e; | |
| 1397 unsigned ix; | |
| 1398 | |
| 1399 for (e = NULL, ix = 0; ix < EDGE_COUNT (b->preds); ix++) | |
| 1400 { | |
| 1401 e = EDGE_PRED (b, ix); | |
| 1402 if (e->src == ENTRY_BLOCK_PTR_FOR_FN (cfun)) | |
| 1403 continue; | |
| 1404 | |
| 1405 bitmap_copy (dst, src[e->src->index]); | |
| 1406 break; | |
| 1407 } | |
| 1408 | |
| 1409 if (e == 0) | |
| 1410 bitmap_ones (dst); | |
| 1411 else | |
| 1412 for (++ix; ix < EDGE_COUNT (b->preds); ix++) | |
| 1413 { | |
| 1414 unsigned int i; | |
| 1415 SBITMAP_ELT_TYPE *p, *r; | |
| 1416 | |
| 1417 e = EDGE_PRED (b, ix); | |
| 1418 if (e->src == ENTRY_BLOCK_PTR_FOR_FN (cfun)) | |
| 1419 continue; | |
| 1420 | |
| 1421 p = src[e->src->index]->elms; | |
| 1422 r = dst->elms; | |
| 1423 for (i = 0; i < set_size; i++) | |
| 1424 *r++ &= *p++; | |
| 1425 } | |
| 1426 } | |
| 1427 | |
| 1428 /* Set the bitmap DST to the union of SRC of successors of | |
| 1429 basic block B. */ | |
| 1430 | |
| 1431 void | |
| 1432 bitmap_union_of_succs (sbitmap dst, sbitmap *src, basic_block b) | |
| 1433 { | |
| 1434 unsigned int set_size = dst->size; | |
| 1435 edge e; | |
| 1436 unsigned ix; | |
| 1437 | |
| 1438 for (ix = 0; ix < EDGE_COUNT (b->succs); ix++) | |
| 1439 { | |
| 1440 e = EDGE_SUCC (b, ix); | |
| 1441 if (e->dest == EXIT_BLOCK_PTR_FOR_FN (cfun)) | |
| 1442 continue; | |
| 1443 | |
| 1444 bitmap_copy (dst, src[e->dest->index]); | |
| 1445 break; | |
| 1446 } | |
| 1447 | |
| 1448 if (ix == EDGE_COUNT (b->succs)) | |
| 1449 bitmap_clear (dst); | |
| 1450 else | |
| 1451 for (ix++; ix < EDGE_COUNT (b->succs); ix++) | |
| 1452 { | |
| 1453 unsigned int i; | |
| 1454 SBITMAP_ELT_TYPE *p, *r; | |
| 1455 | |
| 1456 e = EDGE_SUCC (b, ix); | |
| 1457 if (e->dest == EXIT_BLOCK_PTR_FOR_FN (cfun)) | |
| 1458 continue; | |
| 1459 | |
| 1460 p = src[e->dest->index]->elms; | |
| 1461 r = dst->elms; | |
| 1462 for (i = 0; i < set_size; i++) | |
| 1463 *r++ |= *p++; | |
| 1464 } | |
| 1465 } | |
| 1466 | |
| 1467 /* Set the bitmap DST to the union of SRC of predecessors of | |
| 1468 basic block B. */ | |
| 1469 | |
| 1470 void | |
| 1471 bitmap_union_of_preds (sbitmap dst, sbitmap *src, basic_block b) | |
| 1472 { | |
| 1473 unsigned int set_size = dst->size; | |
| 1474 edge e; | |
| 1475 unsigned ix; | |
| 1476 | |
| 1477 for (ix = 0; ix < EDGE_COUNT (b->preds); ix++) | |
| 1478 { | |
| 1479 e = EDGE_PRED (b, ix); | |
| 1480 if (e->src== ENTRY_BLOCK_PTR_FOR_FN (cfun)) | |
| 1481 continue; | |
| 1482 | |
| 1483 bitmap_copy (dst, src[e->src->index]); | |
| 1484 break; | |
| 1485 } | |
| 1486 | |
| 1487 if (ix == EDGE_COUNT (b->preds)) | |
| 1488 bitmap_clear (dst); | |
| 1489 else | |
| 1490 for (ix++; ix < EDGE_COUNT (b->preds); ix++) | |
| 1491 { | |
| 1492 unsigned int i; | |
| 1493 SBITMAP_ELT_TYPE *p, *r; | |
| 1494 | |
| 1495 e = EDGE_PRED (b, ix); | |
| 1496 if (e->src == ENTRY_BLOCK_PTR_FOR_FN (cfun)) | |
| 1497 continue; | |
| 1498 | |
| 1499 p = src[e->src->index]->elms; | |
| 1500 r = dst->elms; | |
| 1501 for (i = 0; i < set_size; i++) | |
| 1502 *r++ |= *p++; | |
| 1503 } | |
| 1504 } | |
| 1505 | |
| 1506 /* Returns the list of basic blocks in the function in an order that guarantees | |
| 1507 that if a block X has just a single predecessor Y, then Y is after X in the | |
| 1508 ordering. */ | |
| 1509 | |
| 1510 basic_block * | |
| 1511 single_pred_before_succ_order (void) | |
| 1512 { | |
| 1513 basic_block x, y; | |
| 1514 basic_block *order = XNEWVEC (basic_block, n_basic_blocks_for_fn (cfun)); | |
| 1515 unsigned n = n_basic_blocks_for_fn (cfun) - NUM_FIXED_BLOCKS; | |
| 1516 unsigned np, i; | |
| 1517 auto_sbitmap visited (last_basic_block_for_fn (cfun)); | |
| 1518 | |
| 1519 #define MARK_VISITED(BB) (bitmap_set_bit (visited, (BB)->index)) | |
| 1520 #define VISITED_P(BB) (bitmap_bit_p (visited, (BB)->index)) | |
| 1521 | |
| 1522 bitmap_clear (visited); | |
| 1523 | |
| 1524 MARK_VISITED (ENTRY_BLOCK_PTR_FOR_FN (cfun)); | |
| 1525 FOR_EACH_BB_FN (x, cfun) | |
| 1526 { | |
| 1527 if (VISITED_P (x)) | |
| 1528 continue; | |
| 1529 | |
| 1530 /* Walk the predecessors of x as long as they have precisely one | |
| 1531 predecessor and add them to the list, so that they get stored | |
| 1532 after x. */ | |
| 1533 for (y = x, np = 1; | |
| 1534 single_pred_p (y) && !VISITED_P (single_pred (y)); | |
| 1535 y = single_pred (y)) | |
| 1536 np++; | |
| 1537 for (y = x, i = n - np; | |
| 1538 single_pred_p (y) && !VISITED_P (single_pred (y)); | |
| 1539 y = single_pred (y), i++) | |
| 1540 { | |
| 1541 order[i] = y; | |
| 1542 MARK_VISITED (y); | |
| 1543 } | |
| 1544 order[i] = y; | |
| 1545 MARK_VISITED (y); | |
| 1546 | |
| 1547 gcc_assert (i == n - 1); | |
| 1548 n -= np; | |
| 1549 } | |
| 1550 | |
| 1551 gcc_assert (n == 0); | |
| 1552 return order; | |
| 1553 | |
| 1554 #undef MARK_VISITED | |
| 1555 #undef VISITED_P | |
| 1556 } |