Mercurial > hg > CbC > CbC_gcc
annotate gcc/tree-ssa-threadupdate.c @ 144:8f4e72ab4e11
fix segmentation fault caused by nothing next cur_op to end
| author | Takahiro SHIMIZU <anatofuz@cr.ie.u-ryukyu.ac.jp> |
|---|---|
| date | Sun, 23 Dec 2018 21:23:56 +0900 |
| parents | 84e7813d76e9 |
| children | 1830386684a0 |
| rev | line source |
|---|---|
| 0 | 1 /* Thread edges through blocks and update the control flow and SSA graphs. |
| 131 | 2 Copyright (C) 2004-2018 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 | |
| 7 it under the terms of the GNU General Public License as published by | |
| 8 the Free Software Foundation; either version 3, or (at your option) | |
| 9 any later version. | |
| 10 | |
| 11 GCC is distributed in the hope that it will be useful, | |
| 12 but WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
| 14 GNU General Public License 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 #include "config.h" | |
| 21 #include "system.h" | |
| 22 #include "coretypes.h" | |
| 111 | 23 #include "backend.h" |
| 0 | 24 #include "tree.h" |
| 111 | 25 #include "gimple.h" |
| 26 #include "cfghooks.h" | |
| 0 | 27 #include "tree-pass.h" |
| 111 | 28 #include "ssa.h" |
| 29 #include "fold-const.h" | |
| 30 #include "cfganal.h" | |
| 31 #include "gimple-iterator.h" | |
| 32 #include "tree-ssa.h" | |
| 33 #include "tree-ssa-threadupdate.h" | |
| 0 | 34 #include "cfgloop.h" |
| 111 | 35 #include "dbgcnt.h" |
| 36 #include "tree-cfg.h" | |
| 37 #include "tree-vectorizer.h" | |
| 0 | 38 |
| 39 /* Given a block B, update the CFG and SSA graph to reflect redirecting | |
| 40 one or more in-edges to B to instead reach the destination of an | |
| 41 out-edge from B while preserving any side effects in B. | |
| 42 | |
| 43 i.e., given A->B and B->C, change A->B to be A->C yet still preserve the | |
| 44 side effects of executing B. | |
| 45 | |
| 46 1. Make a copy of B (including its outgoing edges and statements). Call | |
| 47 the copy B'. Note B' has no incoming edges or PHIs at this time. | |
| 48 | |
| 49 2. Remove the control statement at the end of B' and all outgoing edges | |
| 50 except B'->C. | |
| 51 | |
| 52 3. Add a new argument to each PHI in C with the same value as the existing | |
| 53 argument associated with edge B->C. Associate the new PHI arguments | |
| 54 with the edge B'->C. | |
| 55 | |
| 56 4. For each PHI in B, find or create a PHI in B' with an identical | |
| 57 PHI_RESULT. Add an argument to the PHI in B' which has the same | |
| 58 value as the PHI in B associated with the edge A->B. Associate | |
| 59 the new argument in the PHI in B' with the edge A->B. | |
| 60 | |
| 61 5. Change the edge A->B to A->B'. | |
| 62 | |
| 63 5a. This automatically deletes any PHI arguments associated with the | |
| 64 edge A->B in B. | |
| 65 | |
| 66 5b. This automatically associates each new argument added in step 4 | |
| 67 with the edge A->B'. | |
| 68 | |
| 69 6. Repeat for other incoming edges into B. | |
| 70 | |
| 71 7. Put the duplicated resources in B and all the B' blocks into SSA form. | |
| 72 | |
| 73 Note that block duplication can be minimized by first collecting the | |
| 74 set of unique destination blocks that the incoming edges should | |
| 111 | 75 be threaded to. |
| 76 | |
| 77 We reduce the number of edges and statements we create by not copying all | |
| 78 the outgoing edges and the control statement in step #1. We instead create | |
| 79 a template block without the outgoing edges and duplicate the template. | |
| 80 | |
| 81 Another case this code handles is threading through a "joiner" block. In | |
| 82 this case, we do not know the destination of the joiner block, but one | |
| 83 of the outgoing edges from the joiner block leads to a threadable path. This | |
| 84 case largely works as outlined above, except the duplicate of the joiner | |
| 85 block still contains a full set of outgoing edges and its control statement. | |
| 86 We just redirect one of its outgoing edges to our jump threading path. */ | |
| 0 | 87 |
| 88 | |
| 89 /* Steps #5 and #6 of the above algorithm are best implemented by walking | |
| 90 all the incoming edges which thread to the same destination edge at | |
| 91 the same time. That avoids lots of table lookups to get information | |
| 92 for the destination edge. | |
| 93 | |
| 94 To realize that implementation we create a list of incoming edges | |
| 95 which thread to the same outgoing edge. Thus to implement steps | |
| 96 #5 and #6 we traverse our hash table of outgoing edge information. | |
| 97 For each entry we walk the list of incoming edges which thread to | |
| 98 the current outgoing edge. */ | |
| 99 | |
| 100 struct el | |
| 101 { | |
| 102 edge e; | |
| 103 struct el *next; | |
| 104 }; | |
| 105 | |
| 106 /* Main data structure recording information regarding B's duplicate | |
| 107 blocks. */ | |
| 108 | |
| 109 /* We need to efficiently record the unique thread destinations of this | |
| 110 block and specific information associated with those destinations. We | |
| 111 may have many incoming edges threaded to the same outgoing edge. This | |
| 112 can be naturally implemented with a hash table. */ | |
| 113 | |
| 111 | 114 struct redirection_data : free_ptr_hash<redirection_data> |
| 115 { | |
| 116 /* We support wiring up two block duplicates in a jump threading path. | |
| 117 | |
| 118 One is a normal block copy where we remove the control statement | |
| 119 and wire up its single remaining outgoing edge to the thread path. | |
| 120 | |
| 121 The other is a joiner block where we leave the control statement | |
| 122 in place, but wire one of the outgoing edges to a thread path. | |
| 123 | |
| 124 In theory we could have multiple block duplicates in a jump | |
| 125 threading path, but I haven't tried that. | |
| 126 | |
| 127 The duplicate blocks appear in this array in the same order in | |
| 128 which they appear in the jump thread path. */ | |
| 129 basic_block dup_blocks[2]; | |
| 130 | |
| 131 /* The jump threading path. */ | |
| 132 vec<jump_thread_edge *> *path; | |
| 133 | |
| 134 /* A list of incoming edges which we want to thread to the | |
| 135 same path. */ | |
| 136 struct el *incoming_edges; | |
| 137 | |
| 138 /* hash_table support. */ | |
| 139 static inline hashval_t hash (const redirection_data *); | |
| 140 static inline int equal (const redirection_data *, const redirection_data *); | |
| 141 }; | |
| 142 | |
| 143 /* Dump a jump threading path, including annotations about each | |
| 144 edge in the path. */ | |
| 145 | |
| 146 static void | |
| 147 dump_jump_thread_path (FILE *dump_file, vec<jump_thread_edge *> path, | |
| 148 bool registering) | |
| 0 | 149 { |
| 111 | 150 fprintf (dump_file, |
| 151 " %s%s jump thread: (%d, %d) incoming edge; ", | |
| 152 (registering ? "Registering" : "Cancelling"), | |
| 153 (path[0]->type == EDGE_FSM_THREAD ? " FSM": ""), | |
| 154 path[0]->e->src->index, path[0]->e->dest->index); | |
| 155 | |
| 156 for (unsigned int i = 1; i < path.length (); i++) | |
| 157 { | |
| 158 /* We can get paths with a NULL edge when the final destination | |
| 159 of a jump thread turns out to be a constant address. We dump | |
| 160 those paths when debugging, so we have to be prepared for that | |
| 161 possibility here. */ | |
| 162 if (path[i]->e == NULL) | |
| 163 continue; | |
| 164 | |
| 165 if (path[i]->type == EDGE_COPY_SRC_JOINER_BLOCK) | |
| 166 fprintf (dump_file, " (%d, %d) joiner; ", | |
| 167 path[i]->e->src->index, path[i]->e->dest->index); | |
| 168 if (path[i]->type == EDGE_COPY_SRC_BLOCK) | |
| 169 fprintf (dump_file, " (%d, %d) normal;", | |
| 170 path[i]->e->src->index, path[i]->e->dest->index); | |
| 171 if (path[i]->type == EDGE_NO_COPY_SRC_BLOCK) | |
| 172 fprintf (dump_file, " (%d, %d) nocopy;", | |
| 173 path[i]->e->src->index, path[i]->e->dest->index); | |
| 174 if (path[0]->type == EDGE_FSM_THREAD) | |
| 175 fprintf (dump_file, " (%d, %d) ", | |
| 176 path[i]->e->src->index, path[i]->e->dest->index); | |
| 177 } | |
| 178 fputc ('\n', dump_file); | |
| 179 } | |
| 180 | |
| 181 /* Simple hashing function. For any given incoming edge E, we're going | |
| 182 to be most concerned with the final destination of its jump thread | |
| 183 path. So hash on the block index of the final edge in the path. */ | |
| 184 | |
| 185 inline hashval_t | |
| 186 redirection_data::hash (const redirection_data *p) | |
| 187 { | |
| 188 vec<jump_thread_edge *> *path = p->path; | |
| 189 return path->last ()->e->dest->index; | |
| 190 } | |
| 191 | |
| 192 /* Given two hash table entries, return true if they have the same | |
| 193 jump threading path. */ | |
| 194 inline int | |
| 195 redirection_data::equal (const redirection_data *p1, const redirection_data *p2) | |
| 196 { | |
| 197 vec<jump_thread_edge *> *path1 = p1->path; | |
| 198 vec<jump_thread_edge *> *path2 = p2->path; | |
| 199 | |
| 200 if (path1->length () != path2->length ()) | |
| 201 return false; | |
| 202 | |
| 203 for (unsigned int i = 1; i < path1->length (); i++) | |
| 204 { | |
| 205 if ((*path1)[i]->type != (*path2)[i]->type | |
| 206 || (*path1)[i]->e != (*path2)[i]->e) | |
| 207 return false; | |
| 208 } | |
| 209 | |
| 210 return true; | |
| 211 } | |
| 212 | |
| 213 /* Rather than search all the edges in jump thread paths each time | |
| 214 DOM is able to simply if control statement, we build a hash table | |
| 215 with the deleted edges. We only care about the address of the edge, | |
| 216 not its contents. */ | |
| 217 struct removed_edges : nofree_ptr_hash<edge_def> | |
| 218 { | |
| 219 static hashval_t hash (edge e) { return htab_hash_pointer (e); } | |
| 220 static bool equal (edge e1, edge e2) { return e1 == e2; } | |
| 0 | 221 }; |
| 222 | |
| 111 | 223 static hash_table<removed_edges> *removed_edges; |
| 0 | 224 |
| 225 /* Data structure of information to pass to hash table traversal routines. */ | |
| 111 | 226 struct ssa_local_info_t |
| 0 | 227 { |
| 228 /* The current block we are working on. */ | |
| 229 basic_block bb; | |
| 230 | |
| 111 | 231 /* We only create a template block for the first duplicated block in a |
| 232 jump threading path as we may need many duplicates of that block. | |
| 233 | |
| 234 The second duplicate block in a path is specific to that path. Creating | |
| 235 and sharing a template for that block is considerably more difficult. */ | |
| 0 | 236 basic_block template_block; |
| 237 | |
| 111 | 238 /* Blocks duplicated for the thread. */ |
| 239 bitmap duplicate_blocks; | |
| 240 | |
| 0 | 241 /* TRUE if we thread one or more jumps, FALSE otherwise. */ |
| 242 bool jumps_threaded; | |
| 111 | 243 |
| 244 /* When we have multiple paths through a joiner which reach different | |
| 245 final destinations, then we may need to correct for potential | |
| 246 profile insanities. */ | |
| 247 bool need_profile_correction; | |
| 0 | 248 }; |
| 249 | |
| 250 /* Passes which use the jump threading code register jump threading | |
| 251 opportunities as they are discovered. We keep the registered | |
| 252 jump threading opportunities in this vector as edge pairs | |
| 253 (original_edge, target_edge). */ | |
| 111 | 254 static vec<vec<jump_thread_edge *> *> paths; |
| 255 | |
| 256 /* When we start updating the CFG for threading, data necessary for jump | |
| 257 threading is attached to the AUX field for the incoming edge. Use these | |
| 258 macros to access the underlying structure attached to the AUX field. */ | |
| 259 #define THREAD_PATH(E) ((vec<jump_thread_edge *> *)(E)->aux) | |
| 0 | 260 |
| 261 /* Jump threading statistics. */ | |
| 262 | |
| 263 struct thread_stats_d | |
| 264 { | |
| 265 unsigned long num_threaded_edges; | |
| 266 }; | |
| 267 | |
| 268 struct thread_stats_d thread_stats; | |
| 269 | |
| 270 | |
| 271 /* Remove the last statement in block BB if it is a control statement | |
| 272 Also remove all outgoing edges except the edge which reaches DEST_BB. | |
| 273 If DEST_BB is NULL, then remove all outgoing edges. */ | |
| 274 | |
| 111 | 275 void |
| 0 | 276 remove_ctrl_stmt_and_useless_edges (basic_block bb, basic_block dest_bb) |
| 277 { | |
| 278 gimple_stmt_iterator gsi; | |
| 279 edge e; | |
| 280 edge_iterator ei; | |
| 281 | |
| 282 gsi = gsi_last_bb (bb); | |
| 283 | |
| 284 /* If the duplicate ends with a control statement, then remove it. | |
| 285 | |
| 286 Note that if we are duplicating the template block rather than the | |
| 287 original basic block, then the duplicate might not have any real | |
| 288 statements in it. */ | |
| 289 if (!gsi_end_p (gsi) | |
| 290 && gsi_stmt (gsi) | |
| 291 && (gimple_code (gsi_stmt (gsi)) == GIMPLE_COND | |
| 292 || gimple_code (gsi_stmt (gsi)) == GIMPLE_GOTO | |
| 293 || gimple_code (gsi_stmt (gsi)) == GIMPLE_SWITCH)) | |
| 294 gsi_remove (&gsi, true); | |
| 295 | |
| 296 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); ) | |
| 297 { | |
| 298 if (e->dest != dest_bb) | |
| 111 | 299 { |
| 300 free_dom_edge_info (e); | |
| 301 remove_edge (e); | |
| 302 } | |
| 0 | 303 else |
| 111 | 304 { |
| 305 e->probability = profile_probability::always (); | |
| 306 ei_next (&ei); | |
| 307 } | |
| 0 | 308 } |
| 111 | 309 |
| 310 /* If the remaining edge is a loop exit, there must have | |
| 311 a removed edge that was not a loop exit. | |
| 312 | |
| 313 In that case BB and possibly other blocks were previously | |
| 314 in the loop, but are now outside the loop. Thus, we need | |
| 315 to update the loop structures. */ | |
| 316 if (single_succ_p (bb) | |
| 317 && loop_outer (bb->loop_father) | |
| 318 && loop_exit_edge_p (bb->loop_father, single_succ_edge (bb))) | |
| 319 loops_state_set (LOOPS_NEED_FIXUP); | |
| 0 | 320 } |
| 321 | |
| 111 | 322 /* Create a duplicate of BB. Record the duplicate block in an array |
| 323 indexed by COUNT stored in RD. */ | |
| 0 | 324 |
| 325 static void | |
| 111 | 326 create_block_for_threading (basic_block bb, |
| 327 struct redirection_data *rd, | |
| 328 unsigned int count, | |
| 329 bitmap *duplicate_blocks) | |
| 0 | 330 { |
| 111 | 331 edge_iterator ei; |
| 332 edge e; | |
| 333 | |
| 0 | 334 /* We can use the generic block duplication code and simply remove |
| 335 the stuff we do not need. */ | |
| 111 | 336 rd->dup_blocks[count] = duplicate_block (bb, NULL, NULL); |
| 337 | |
| 338 FOR_EACH_EDGE (e, ei, rd->dup_blocks[count]->succs) | |
| 339 e->aux = NULL; | |
| 0 | 340 |
| 341 /* Zero out the profile, since the block is unreachable for now. */ | |
| 111 | 342 rd->dup_blocks[count]->count = profile_count::uninitialized (); |
| 343 if (duplicate_blocks) | |
| 344 bitmap_set_bit (*duplicate_blocks, rd->dup_blocks[count]->index); | |
| 0 | 345 } |
| 346 | |
| 111 | 347 /* Main data structure to hold information for duplicates of BB. */ |
| 348 | |
| 349 static hash_table<redirection_data> *redirection_data; | |
| 0 | 350 |
| 351 /* Given an outgoing edge E lookup and return its entry in our hash table. | |
| 352 | |
| 353 If INSERT is true, then we insert the entry into the hash table if | |
| 354 it is not already present. INCOMING_EDGE is added to the list of incoming | |
| 355 edges associated with E in the hash table. */ | |
| 356 | |
| 357 static struct redirection_data * | |
| 111 | 358 lookup_redirection_data (edge e, enum insert_option insert) |
| 0 | 359 { |
| 111 | 360 struct redirection_data **slot; |
| 0 | 361 struct redirection_data *elt; |
| 111 | 362 vec<jump_thread_edge *> *path = THREAD_PATH (e); |
| 363 | |
| 364 /* Build a hash table element so we can see if E is already | |
| 0 | 365 in the table. */ |
| 366 elt = XNEW (struct redirection_data); | |
| 111 | 367 elt->path = path; |
| 368 elt->dup_blocks[0] = NULL; | |
| 369 elt->dup_blocks[1] = NULL; | |
| 0 | 370 elt->incoming_edges = NULL; |
| 371 | |
| 111 | 372 slot = redirection_data->find_slot (elt, insert); |
| 0 | 373 |
| 374 /* This will only happen if INSERT is false and the entry is not | |
| 375 in the hash table. */ | |
| 376 if (slot == NULL) | |
| 377 { | |
| 378 free (elt); | |
| 379 return NULL; | |
| 380 } | |
| 381 | |
| 382 /* This will only happen if E was not in the hash table and | |
| 383 INSERT is true. */ | |
| 384 if (*slot == NULL) | |
| 385 { | |
| 111 | 386 *slot = elt; |
| 0 | 387 elt->incoming_edges = XNEW (struct el); |
| 111 | 388 elt->incoming_edges->e = e; |
| 0 | 389 elt->incoming_edges->next = NULL; |
| 390 return elt; | |
| 391 } | |
| 392 /* E was in the hash table. */ | |
| 393 else | |
| 394 { | |
| 395 /* Free ELT as we do not need it anymore, we will extract the | |
| 396 relevant entry from the hash table itself. */ | |
| 397 free (elt); | |
| 398 | |
| 399 /* Get the entry stored in the hash table. */ | |
| 111 | 400 elt = *slot; |
| 0 | 401 |
| 402 /* If insertion was requested, then we need to add INCOMING_EDGE | |
| 403 to the list of incoming edges associated with E. */ | |
| 404 if (insert) | |
| 405 { | |
| 111 | 406 struct el *el = XNEW (struct el); |
| 0 | 407 el->next = elt->incoming_edges; |
| 111 | 408 el->e = e; |
| 0 | 409 elt->incoming_edges = el; |
| 410 } | |
| 411 | |
| 412 return elt; | |
| 413 } | |
| 414 } | |
| 415 | |
| 111 | 416 /* Similar to copy_phi_args, except that the PHI arg exists, it just |
| 417 does not have a value associated with it. */ | |
| 418 | |
| 419 static void | |
| 420 copy_phi_arg_into_existing_phi (edge src_e, edge tgt_e) | |
| 421 { | |
| 422 int src_idx = src_e->dest_idx; | |
| 423 int tgt_idx = tgt_e->dest_idx; | |
| 424 | |
| 425 /* Iterate over each PHI in e->dest. */ | |
| 426 for (gphi_iterator gsi = gsi_start_phis (src_e->dest), | |
| 427 gsi2 = gsi_start_phis (tgt_e->dest); | |
| 428 !gsi_end_p (gsi); | |
| 429 gsi_next (&gsi), gsi_next (&gsi2)) | |
| 430 { | |
| 431 gphi *src_phi = gsi.phi (); | |
| 432 gphi *dest_phi = gsi2.phi (); | |
| 433 tree val = gimple_phi_arg_def (src_phi, src_idx); | |
| 434 source_location locus = gimple_phi_arg_location (src_phi, src_idx); | |
| 435 | |
| 436 SET_PHI_ARG_DEF (dest_phi, tgt_idx, val); | |
| 437 gimple_phi_arg_set_location (dest_phi, tgt_idx, locus); | |
| 438 } | |
| 439 } | |
| 440 | |
| 441 /* Given ssa_name DEF, backtrack jump threading PATH from node IDX | |
| 442 to see if it has constant value in a flow sensitive manner. Set | |
| 443 LOCUS to location of the constant phi arg and return the value. | |
| 444 Return DEF directly if either PATH or idx is ZERO. */ | |
| 445 | |
| 446 static tree | |
| 447 get_value_locus_in_path (tree def, vec<jump_thread_edge *> *path, | |
| 448 basic_block bb, int idx, source_location *locus) | |
| 449 { | |
| 450 tree arg; | |
| 451 gphi *def_phi; | |
| 452 basic_block def_bb; | |
| 453 | |
| 454 if (path == NULL || idx == 0) | |
| 455 return def; | |
| 456 | |
| 457 def_phi = dyn_cast <gphi *> (SSA_NAME_DEF_STMT (def)); | |
| 458 if (!def_phi) | |
| 459 return def; | |
| 460 | |
| 461 def_bb = gimple_bb (def_phi); | |
| 462 /* Don't propagate loop invariants into deeper loops. */ | |
| 463 if (!def_bb || bb_loop_depth (def_bb) < bb_loop_depth (bb)) | |
| 464 return def; | |
| 465 | |
| 466 /* Backtrack jump threading path from IDX to see if def has constant | |
| 467 value. */ | |
| 468 for (int j = idx - 1; j >= 0; j--) | |
| 469 { | |
| 470 edge e = (*path)[j]->e; | |
| 471 if (e->dest == def_bb) | |
| 472 { | |
| 473 arg = gimple_phi_arg_def (def_phi, e->dest_idx); | |
| 474 if (is_gimple_min_invariant (arg)) | |
| 475 { | |
| 476 *locus = gimple_phi_arg_location (def_phi, e->dest_idx); | |
| 477 return arg; | |
| 478 } | |
| 479 break; | |
| 480 } | |
| 481 } | |
| 482 | |
| 483 return def; | |
| 484 } | |
| 485 | |
| 486 /* For each PHI in BB, copy the argument associated with SRC_E to TGT_E. | |
| 487 Try to backtrack jump threading PATH from node IDX to see if the arg | |
| 488 has constant value, copy constant value instead of argument itself | |
| 489 if yes. */ | |
| 490 | |
| 491 static void | |
| 492 copy_phi_args (basic_block bb, edge src_e, edge tgt_e, | |
| 493 vec<jump_thread_edge *> *path, int idx) | |
| 494 { | |
| 495 gphi_iterator gsi; | |
| 496 int src_indx = src_e->dest_idx; | |
| 497 | |
| 498 for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi)) | |
| 499 { | |
| 500 gphi *phi = gsi.phi (); | |
| 501 tree def = gimple_phi_arg_def (phi, src_indx); | |
| 502 source_location locus = gimple_phi_arg_location (phi, src_indx); | |
| 503 | |
| 504 if (TREE_CODE (def) == SSA_NAME | |
| 505 && !virtual_operand_p (gimple_phi_result (phi))) | |
| 506 def = get_value_locus_in_path (def, path, bb, idx, &locus); | |
| 507 | |
| 508 add_phi_arg (phi, def, tgt_e, locus); | |
| 509 } | |
| 510 } | |
| 511 | |
| 512 /* We have recently made a copy of ORIG_BB, including its outgoing | |
| 513 edges. The copy is NEW_BB. Every PHI node in every direct successor of | |
| 514 ORIG_BB has a new argument associated with edge from NEW_BB to the | |
| 515 successor. Initialize the PHI argument so that it is equal to the PHI | |
| 516 argument associated with the edge from ORIG_BB to the successor. | |
| 517 PATH and IDX are used to check if the new PHI argument has constant | |
| 518 value in a flow sensitive manner. */ | |
| 519 | |
| 520 static void | |
| 521 update_destination_phis (basic_block orig_bb, basic_block new_bb, | |
| 522 vec<jump_thread_edge *> *path, int idx) | |
| 523 { | |
| 524 edge_iterator ei; | |
| 525 edge e; | |
| 526 | |
| 527 FOR_EACH_EDGE (e, ei, orig_bb->succs) | |
| 528 { | |
| 529 edge e2 = find_edge (new_bb, e->dest); | |
| 530 copy_phi_args (e->dest, e, e2, path, idx); | |
| 531 } | |
| 532 } | |
| 533 | |
| 0 | 534 /* Given a duplicate block and its single destination (both stored |
| 535 in RD). Create an edge between the duplicate and its single | |
| 536 destination. | |
| 537 | |
| 538 Add an additional argument to any PHI nodes at the single | |
| 111 | 539 destination. IDX is the start node in jump threading path |
| 540 we start to check to see if the new PHI argument has constant | |
| 541 value along the jump threading path. */ | |
| 0 | 542 |
| 543 static void | |
| 111 | 544 create_edge_and_update_destination_phis (struct redirection_data *rd, |
| 545 basic_block bb, int idx) | |
| 0 | 546 { |
| 111 | 547 edge e = make_single_succ_edge (bb, rd->path->last ()->e->dest, EDGE_FALLTHRU); |
| 0 | 548 |
| 549 rescan_loop_exit (e, true, false); | |
| 111 | 550 |
| 551 /* We used to copy the thread path here. That was added in 2007 | |
| 552 and dutifully updated through the representation changes in 2013. | |
| 553 | |
| 554 In 2013 we added code to thread from an interior node through | |
| 555 the backedge to another interior node. That runs after the code | |
| 556 to thread through loop headers from outside the loop. | |
| 557 | |
| 558 The latter may delete edges in the CFG, including those | |
| 559 which appeared in the jump threading path we copied here. Thus | |
| 560 we'd end up using a dangling pointer. | |
| 561 | |
| 562 After reviewing the 2007/2011 code, I can't see how anything | |
| 563 depended on copying the AUX field and clearly copying the jump | |
| 564 threading path is problematical due to embedded edge pointers. | |
| 565 It has been removed. */ | |
| 566 e->aux = NULL; | |
| 0 | 567 |
| 568 /* If there are any PHI nodes at the destination of the outgoing edge | |
| 569 from the duplicate block, then we will need to add a new argument | |
| 570 to them. The argument should have the same value as the argument | |
| 571 associated with the outgoing edge stored in RD. */ | |
| 111 | 572 copy_phi_args (e->dest, rd->path->last ()->e, e, rd->path, idx); |
| 573 } | |
| 574 | |
| 575 /* Look through PATH beginning at START and return TRUE if there are | |
| 576 any additional blocks that need to be duplicated. Otherwise, | |
| 577 return FALSE. */ | |
| 578 static bool | |
| 579 any_remaining_duplicated_blocks (vec<jump_thread_edge *> *path, | |
| 580 unsigned int start) | |
| 581 { | |
| 582 for (unsigned int i = start + 1; i < path->length (); i++) | |
| 583 { | |
| 584 if ((*path)[i]->type == EDGE_COPY_SRC_JOINER_BLOCK | |
| 585 || (*path)[i]->type == EDGE_COPY_SRC_BLOCK) | |
| 586 return true; | |
| 587 } | |
| 588 return false; | |
| 589 } | |
| 590 | |
| 591 | |
| 131 | 592 /* Compute the amount of profile count coming into the jump threading |
| 111 | 593 path stored in RD that we are duplicating, returned in PATH_IN_COUNT_PTR and |
| 594 PATH_IN_FREQ_PTR, as well as the amount of counts flowing out of the | |
| 595 duplicated path, returned in PATH_OUT_COUNT_PTR. LOCAL_INFO is used to | |
| 596 identify blocks duplicated for jump threading, which have duplicated | |
| 597 edges that need to be ignored in the analysis. Return true if path contains | |
| 598 a joiner, false otherwise. | |
| 599 | |
| 131 | 600 In the non-joiner case, this is straightforward - all the counts |
| 111 | 601 flowing into the jump threading path should flow through the duplicated |
| 602 block and out of the duplicated path. | |
| 603 | |
| 604 In the joiner case, it is very tricky. Some of the counts flowing into | |
| 605 the original path go offpath at the joiner. The problem is that while | |
| 606 we know how much total count goes off-path in the original control flow, | |
| 607 we don't know how many of the counts corresponding to just the jump | |
| 608 threading path go offpath at the joiner. | |
| 609 | |
| 610 For example, assume we have the following control flow and identified | |
| 611 jump threading paths: | |
| 612 | |
| 613 A B C | |
| 614 \ | / | |
| 615 Ea \ |Eb / Ec | |
| 616 \ | / | |
| 617 v v v | |
| 618 J <-- Joiner | |
| 619 / \ | |
| 620 Eoff/ \Eon | |
| 621 / \ | |
| 622 v v | |
| 623 Soff Son <--- Normal | |
| 624 /\ | |
| 625 Ed/ \ Ee | |
| 626 / \ | |
| 627 v v | |
| 628 D E | |
| 629 | |
| 630 Jump threading paths: A -> J -> Son -> D (path 1) | |
| 631 C -> J -> Son -> E (path 2) | |
| 632 | |
| 633 Note that the control flow could be more complicated: | |
| 634 - Each jump threading path may have more than one incoming edge. I.e. A and | |
| 635 Ea could represent multiple incoming blocks/edges that are included in | |
| 636 path 1. | |
| 637 - There could be EDGE_NO_COPY_SRC_BLOCK edges after the joiner (either | |
| 638 before or after the "normal" copy block). These are not duplicated onto | |
| 639 the jump threading path, as they are single-successor. | |
| 640 - Any of the blocks along the path may have other incoming edges that | |
| 641 are not part of any jump threading path, but add profile counts along | |
| 642 the path. | |
| 643 | |
| 644 In the above example, after all jump threading is complete, we will | |
| 645 end up with the following control flow: | |
| 646 | |
| 647 A B C | |
| 648 | | | | |
| 649 Ea| |Eb |Ec | |
| 650 | | | | |
| 651 v v v | |
| 652 Ja J Jc | |
| 653 / \ / \Eon' / \ | |
| 654 Eona/ \ ---/---\-------- \Eonc | |
| 655 / \ / / \ \ | |
| 656 v v v v v | |
| 657 Sona Soff Son Sonc | |
| 658 \ /\ / | |
| 659 \___________ / \ _____/ | |
| 660 \ / \/ | |
| 661 vv v | |
| 662 D E | |
| 663 | |
| 664 The main issue to notice here is that when we are processing path 1 | |
| 665 (A->J->Son->D) we need to figure out the outgoing edge weights to | |
| 666 the duplicated edges Ja->Sona and Ja->Soff, while ensuring that the | |
| 667 sum of the incoming weights to D remain Ed. The problem with simply | |
| 668 assuming that Ja (and Jc when processing path 2) has the same outgoing | |
| 669 probabilities to its successors as the original block J, is that after | |
| 670 all paths are processed and other edges/counts removed (e.g. none | |
| 671 of Ec will reach D after processing path 2), we may end up with not | |
| 672 enough count flowing along duplicated edge Sona->D. | |
| 673 | |
| 674 Therefore, in the case of a joiner, we keep track of all counts | |
| 675 coming in along the current path, as well as from predecessors not | |
| 676 on any jump threading path (Eb in the above example). While we | |
| 677 first assume that the duplicated Eona for Ja->Sona has the same | |
| 678 probability as the original, we later compensate for other jump | |
| 679 threading paths that may eliminate edges. We do that by keep track | |
| 680 of all counts coming into the original path that are not in a jump | |
| 681 thread (Eb in the above example, but as noted earlier, there could | |
| 682 be other predecessors incoming to the path at various points, such | |
| 683 as at Son). Call this cumulative non-path count coming into the path | |
| 684 before D as Enonpath. We then ensure that the count from Sona->D is as at | |
| 685 least as big as (Ed - Enonpath), but no bigger than the minimum | |
| 686 weight along the jump threading path. The probabilities of both the | |
| 687 original and duplicated joiner block J and Ja will be adjusted | |
| 688 accordingly after the updates. */ | |
| 689 | |
| 690 static bool | |
| 691 compute_path_counts (struct redirection_data *rd, | |
| 692 ssa_local_info_t *local_info, | |
| 693 profile_count *path_in_count_ptr, | |
| 131 | 694 profile_count *path_out_count_ptr) |
| 111 | 695 { |
| 696 edge e = rd->incoming_edges->e; | |
| 697 vec<jump_thread_edge *> *path = THREAD_PATH (e); | |
| 698 edge elast = path->last ()->e; | |
| 699 profile_count nonpath_count = profile_count::zero (); | |
| 700 bool has_joiner = false; | |
| 701 profile_count path_in_count = profile_count::zero (); | |
| 702 | |
| 703 /* Start by accumulating incoming edge counts to the path's first bb | |
| 704 into a couple buckets: | |
| 705 path_in_count: total count of incoming edges that flow into the | |
| 706 current path. | |
| 707 nonpath_count: total count of incoming edges that are not | |
| 708 flowing along *any* path. These are the counts | |
| 709 that will still flow along the original path after | |
| 710 all path duplication is done by potentially multiple | |
| 711 calls to this routine. | |
| 712 (any other incoming edge counts are for a different jump threading | |
| 713 path that will be handled by a later call to this routine.) | |
| 714 To make this easier, start by recording all incoming edges that flow into | |
| 715 the current path in a bitmap. We could add up the path's incoming edge | |
| 716 counts here, but we still need to walk all the first bb's incoming edges | |
| 717 below to add up the counts of the other edges not included in this jump | |
| 718 threading path. */ | |
| 719 struct el *next, *el; | |
| 720 auto_bitmap in_edge_srcs; | |
| 721 for (el = rd->incoming_edges; el; el = next) | |
| 722 { | |
| 723 next = el->next; | |
| 724 bitmap_set_bit (in_edge_srcs, el->e->src->index); | |
| 725 } | |
| 726 edge ein; | |
| 727 edge_iterator ei; | |
| 728 FOR_EACH_EDGE (ein, ei, e->dest->preds) | |
| 729 { | |
| 730 vec<jump_thread_edge *> *ein_path = THREAD_PATH (ein); | |
| 731 /* Simply check the incoming edge src against the set captured above. */ | |
| 732 if (ein_path | |
| 733 && bitmap_bit_p (in_edge_srcs, (*ein_path)[0]->e->src->index)) | |
| 734 { | |
| 735 /* It is necessary but not sufficient that the last path edges | |
| 736 are identical. There may be different paths that share the | |
| 737 same last path edge in the case where the last edge has a nocopy | |
| 738 source block. */ | |
| 739 gcc_assert (ein_path->last ()->e == elast); | |
| 740 path_in_count += ein->count (); | |
| 741 } | |
| 742 else if (!ein_path) | |
| 743 { | |
| 744 /* Keep track of the incoming edges that are not on any jump-threading | |
| 745 path. These counts will still flow out of original path after all | |
| 746 jump threading is complete. */ | |
| 747 nonpath_count += ein->count (); | |
| 748 } | |
| 749 } | |
| 750 | |
| 751 /* Now compute the fraction of the total count coming into the first | |
| 752 path bb that is from the current threading path. */ | |
| 753 profile_count total_count = e->dest->count; | |
| 754 /* Handle incoming profile insanities. */ | |
| 755 if (total_count < path_in_count) | |
| 756 path_in_count = total_count; | |
| 757 profile_probability onpath_scale = path_in_count.probability_in (total_count); | |
| 758 | |
| 759 /* Walk the entire path to do some more computation in order to estimate | |
| 760 how much of the path_in_count will flow out of the duplicated threading | |
| 761 path. In the non-joiner case this is straightforward (it should be | |
| 762 the same as path_in_count, although we will handle incoming profile | |
| 763 insanities by setting it equal to the minimum count along the path). | |
| 764 | |
| 765 In the joiner case, we need to estimate how much of the path_in_count | |
| 766 will stay on the threading path after the joiner's conditional branch. | |
| 767 We don't really know for sure how much of the counts | |
| 768 associated with this path go to each successor of the joiner, but we'll | |
| 769 estimate based on the fraction of the total count coming into the path | |
| 770 bb was from the threading paths (computed above in onpath_scale). | |
| 771 Afterwards, we will need to do some fixup to account for other threading | |
| 772 paths and possible profile insanities. | |
| 773 | |
| 774 In order to estimate the joiner case's counts we also need to update | |
| 775 nonpath_count with any additional counts coming into the path. Other | |
| 776 blocks along the path may have additional predecessors from outside | |
| 777 the path. */ | |
| 778 profile_count path_out_count = path_in_count; | |
| 779 profile_count min_path_count = path_in_count; | |
| 780 for (unsigned int i = 1; i < path->length (); i++) | |
| 781 { | |
| 782 edge epath = (*path)[i]->e; | |
| 783 profile_count cur_count = epath->count (); | |
| 784 if ((*path)[i]->type == EDGE_COPY_SRC_JOINER_BLOCK) | |
| 785 { | |
| 786 has_joiner = true; | |
| 787 cur_count = cur_count.apply_probability (onpath_scale); | |
| 788 } | |
| 789 /* In the joiner case we need to update nonpath_count for any edges | |
| 790 coming into the path that will contribute to the count flowing | |
| 791 into the path successor. */ | |
| 792 if (has_joiner && epath != elast) | |
| 793 { | |
| 794 /* Look for other incoming edges after joiner. */ | |
| 795 FOR_EACH_EDGE (ein, ei, epath->dest->preds) | |
| 796 { | |
| 797 if (ein != epath | |
| 798 /* Ignore in edges from blocks we have duplicated for a | |
| 799 threading path, which have duplicated edge counts until | |
| 800 they are redirected by an invocation of this routine. */ | |
| 801 && !bitmap_bit_p (local_info->duplicate_blocks, | |
| 802 ein->src->index)) | |
| 803 nonpath_count += ein->count (); | |
| 804 } | |
| 805 } | |
| 806 if (cur_count < path_out_count) | |
| 807 path_out_count = cur_count; | |
| 808 if (epath->count () < min_path_count) | |
| 809 min_path_count = epath->count (); | |
| 810 } | |
| 811 | |
| 812 /* We computed path_out_count above assuming that this path targeted | |
| 813 the joiner's on-path successor with the same likelihood as it | |
| 814 reached the joiner. However, other thread paths through the joiner | |
| 815 may take a different path through the normal copy source block | |
| 816 (i.e. they have a different elast), meaning that they do not | |
| 817 contribute any counts to this path's elast. As a result, it may | |
| 818 turn out that this path must have more count flowing to the on-path | |
| 819 successor of the joiner. Essentially, all of this path's elast | |
| 820 count must be contributed by this path and any nonpath counts | |
| 821 (since any path through the joiner with a different elast will not | |
| 822 include a copy of this elast in its duplicated path). | |
| 823 So ensure that this path's path_out_count is at least the | |
| 824 difference between elast->count () and nonpath_count. Otherwise the edge | |
| 825 counts after threading will not be sane. */ | |
| 826 if (local_info->need_profile_correction | |
| 827 && has_joiner && path_out_count < elast->count () - nonpath_count) | |
| 828 { | |
| 829 path_out_count = elast->count () - nonpath_count; | |
| 830 /* But neither can we go above the minimum count along the path | |
| 831 we are duplicating. This can be an issue due to profile | |
| 832 insanities coming in to this pass. */ | |
| 833 if (path_out_count > min_path_count) | |
| 834 path_out_count = min_path_count; | |
| 835 } | |
| 836 | |
| 837 *path_in_count_ptr = path_in_count; | |
| 838 *path_out_count_ptr = path_out_count; | |
| 839 return has_joiner; | |
| 840 } | |
| 841 | |
| 842 | |
| 843 /* Update the counts and frequencies for both an original path | |
| 844 edge EPATH and its duplicate EDUP. The duplicate source block | |
| 131 | 845 will get a count of PATH_IN_COUNT and PATH_IN_FREQ, |
| 111 | 846 and the duplicate edge EDUP will have a count of PATH_OUT_COUNT. */ |
| 847 static void | |
| 848 update_profile (edge epath, edge edup, profile_count path_in_count, | |
| 131 | 849 profile_count path_out_count) |
| 111 | 850 { |
| 131 | 851 |
| 852 /* First update the duplicated block's count. */ | |
| 111 | 853 if (edup) |
| 0 | 854 { |
| 111 | 855 basic_block dup_block = edup->src; |
| 856 | |
| 857 /* Edup's count is reduced by path_out_count. We need to redistribute | |
| 858 probabilities to the remaining edges. */ | |
| 859 | |
| 860 edge esucc; | |
| 861 edge_iterator ei; | |
| 862 profile_probability edup_prob | |
| 863 = path_out_count.probability_in (path_in_count); | |
| 864 | |
| 865 /* Either scale up or down the remaining edges. | |
| 866 probabilities are always in range <0,1> and thus we can't do | |
| 867 both by same loop. */ | |
| 868 if (edup->probability > edup_prob) | |
| 869 { | |
| 870 profile_probability rev_scale | |
| 871 = (profile_probability::always () - edup->probability) | |
| 872 / (profile_probability::always () - edup_prob); | |
| 873 FOR_EACH_EDGE (esucc, ei, dup_block->succs) | |
| 874 if (esucc != edup) | |
| 875 esucc->probability /= rev_scale; | |
| 876 } | |
| 877 else if (edup->probability < edup_prob) | |
| 878 { | |
| 879 profile_probability scale | |
| 880 = (profile_probability::always () - edup_prob) | |
| 881 / (profile_probability::always () - edup->probability); | |
| 882 FOR_EACH_EDGE (esucc, ei, dup_block->succs) | |
| 883 if (esucc != edup) | |
| 884 esucc->probability *= scale; | |
| 885 } | |
| 131 | 886 if (edup_prob.initialized_p ()) |
| 887 edup->probability = edup_prob; | |
| 888 | |
| 889 gcc_assert (!dup_block->count.initialized_p ()); | |
| 111 | 890 dup_block->count = path_in_count; |
| 891 } | |
| 892 | |
| 131 | 893 if (path_in_count == profile_count::zero ()) |
| 894 return; | |
| 895 | |
| 111 | 896 profile_count final_count = epath->count () - path_out_count; |
| 897 | |
| 131 | 898 /* Now update the original block's count in the |
| 111 | 899 opposite manner - remove the counts/freq that will flow |
| 900 into the duplicated block. Handle underflow due to precision/ | |
| 901 rounding issues. */ | |
| 902 epath->src->count -= path_in_count; | |
| 903 | |
| 904 /* Next update this path edge's original and duplicated counts. We know | |
| 905 that the duplicated path will have path_out_count flowing | |
| 906 out of it (in the joiner case this is the count along the duplicated path | |
| 907 out of the duplicated joiner). This count can then be removed from the | |
| 908 original path edge. */ | |
| 131 | 909 |
| 910 edge esucc; | |
| 911 edge_iterator ei; | |
| 912 profile_probability epath_prob = final_count.probability_in (epath->src->count); | |
| 913 | |
| 914 if (epath->probability > epath_prob) | |
| 111 | 915 { |
| 131 | 916 profile_probability rev_scale |
| 917 = (profile_probability::always () - epath->probability) | |
| 918 / (profile_probability::always () - epath_prob); | |
| 919 FOR_EACH_EDGE (esucc, ei, epath->src->succs) | |
| 920 if (esucc != epath) | |
| 921 esucc->probability /= rev_scale; | |
| 111 | 922 } |
| 131 | 923 else if (epath->probability < epath_prob) |
| 111 | 924 { |
| 131 | 925 profile_probability scale |
| 926 = (profile_probability::always () - epath_prob) | |
| 927 / (profile_probability::always () - epath->probability); | |
| 928 FOR_EACH_EDGE (esucc, ei, epath->src->succs) | |
| 929 if (esucc != epath) | |
| 930 esucc->probability *= scale; | |
| 0 | 931 } |
| 131 | 932 if (epath_prob.initialized_p ()) |
| 933 epath->probability = epath_prob; | |
| 111 | 934 } |
| 935 | |
| 936 /* Wire up the outgoing edges from the duplicate blocks and | |
| 937 update any PHIs as needed. Also update the profile counts | |
| 938 on the original and duplicate blocks and edges. */ | |
| 939 void | |
| 940 ssa_fix_duplicate_block_edges (struct redirection_data *rd, | |
| 941 ssa_local_info_t *local_info) | |
| 942 { | |
| 943 bool multi_incomings = (rd->incoming_edges->next != NULL); | |
| 944 edge e = rd->incoming_edges->e; | |
| 945 vec<jump_thread_edge *> *path = THREAD_PATH (e); | |
| 946 edge elast = path->last ()->e; | |
| 947 profile_count path_in_count = profile_count::zero (); | |
| 948 profile_count path_out_count = profile_count::zero (); | |
| 949 | |
| 950 /* First determine how much profile count to move from original | |
| 951 path to the duplicate path. This is tricky in the presence of | |
| 952 a joiner (see comments for compute_path_counts), where some portion | |
| 953 of the path's counts will flow off-path from the joiner. In the | |
| 954 non-joiner case the path_in_count and path_out_count should be the | |
| 955 same. */ | |
| 956 bool has_joiner = compute_path_counts (rd, local_info, | |
| 131 | 957 &path_in_count, &path_out_count); |
| 958 | |
| 111 | 959 for (unsigned int count = 0, i = 1; i < path->length (); i++) |
| 960 { | |
| 961 edge epath = (*path)[i]->e; | |
| 962 | |
| 963 /* If we were threading through an joiner block, then we want | |
| 964 to keep its control statement and redirect an outgoing edge. | |
| 965 Else we want to remove the control statement & edges, then create | |
| 966 a new outgoing edge. In both cases we may need to update PHIs. */ | |
| 967 if ((*path)[i]->type == EDGE_COPY_SRC_JOINER_BLOCK) | |
| 968 { | |
| 969 edge victim; | |
| 970 edge e2; | |
| 971 | |
| 972 gcc_assert (has_joiner); | |
| 973 | |
| 974 /* This updates the PHIs at the destination of the duplicate | |
| 975 block. Pass 0 instead of i if we are threading a path which | |
| 976 has multiple incoming edges. */ | |
| 977 update_destination_phis (local_info->bb, rd->dup_blocks[count], | |
| 978 path, multi_incomings ? 0 : i); | |
| 979 | |
| 980 /* Find the edge from the duplicate block to the block we're | |
| 981 threading through. That's the edge we want to redirect. */ | |
| 982 victim = find_edge (rd->dup_blocks[count], (*path)[i]->e->dest); | |
| 983 | |
| 984 /* If there are no remaining blocks on the path to duplicate, | |
| 985 then redirect VICTIM to the final destination of the jump | |
| 986 threading path. */ | |
| 987 if (!any_remaining_duplicated_blocks (path, i)) | |
| 988 { | |
| 989 e2 = redirect_edge_and_branch (victim, elast->dest); | |
| 990 /* If we redirected the edge, then we need to copy PHI arguments | |
| 991 at the target. If the edge already existed (e2 != victim | |
| 992 case), then the PHIs in the target already have the correct | |
| 993 arguments. */ | |
| 994 if (e2 == victim) | |
| 995 copy_phi_args (e2->dest, elast, e2, | |
| 996 path, multi_incomings ? 0 : i); | |
| 997 } | |
| 998 else | |
| 999 { | |
| 1000 /* Redirect VICTIM to the next duplicated block in the path. */ | |
| 1001 e2 = redirect_edge_and_branch (victim, rd->dup_blocks[count + 1]); | |
| 1002 | |
| 1003 /* We need to update the PHIs in the next duplicated block. We | |
| 1004 want the new PHI args to have the same value as they had | |
| 1005 in the source of the next duplicate block. | |
| 1006 | |
| 1007 Thus, we need to know which edge we traversed into the | |
| 1008 source of the duplicate. Furthermore, we may have | |
| 1009 traversed many edges to reach the source of the duplicate. | |
| 1010 | |
| 1011 Walk through the path starting at element I until we | |
| 1012 hit an edge marked with EDGE_COPY_SRC_BLOCK. We want | |
| 1013 the edge from the prior element. */ | |
| 1014 for (unsigned int j = i + 1; j < path->length (); j++) | |
| 1015 { | |
| 1016 if ((*path)[j]->type == EDGE_COPY_SRC_BLOCK) | |
| 1017 { | |
| 1018 copy_phi_arg_into_existing_phi ((*path)[j - 1]->e, e2); | |
| 1019 break; | |
| 1020 } | |
| 1021 } | |
| 1022 } | |
| 1023 | |
| 131 | 1024 /* Update the counts of both the original block |
| 111 | 1025 and path edge, and the duplicates. The path duplicate's |
| 131 | 1026 incoming count are the totals for all edges |
| 111 | 1027 incoming to this jump threading path computed earlier. |
| 1028 And we know that the duplicated path will have path_out_count | |
| 1029 flowing out of it (i.e. along the duplicated path out of the | |
| 1030 duplicated joiner). */ | |
| 131 | 1031 update_profile (epath, e2, path_in_count, path_out_count); |
| 111 | 1032 } |
| 1033 else if ((*path)[i]->type == EDGE_COPY_SRC_BLOCK) | |
| 1034 { | |
| 1035 remove_ctrl_stmt_and_useless_edges (rd->dup_blocks[count], NULL); | |
| 1036 create_edge_and_update_destination_phis (rd, rd->dup_blocks[count], | |
| 1037 multi_incomings ? 0 : i); | |
| 1038 if (count == 1) | |
| 1039 single_succ_edge (rd->dup_blocks[1])->aux = NULL; | |
| 1040 | |
| 131 | 1041 /* Update the counts of both the original block |
| 111 | 1042 and path edge, and the duplicates. Since we are now after |
| 1043 any joiner that may have existed on the path, the count | |
| 1044 flowing along the duplicated threaded path is path_out_count. | |
| 1045 If we didn't have a joiner, then cur_path_freq was the sum | |
| 1046 of the total frequencies along all incoming edges to the | |
| 1047 thread path (path_in_freq). If we had a joiner, it would have | |
| 1048 been updated at the end of that handling to the edge frequency | |
| 1049 along the duplicated joiner path edge. */ | |
| 1050 update_profile (epath, EDGE_SUCC (rd->dup_blocks[count], 0), | |
| 131 | 1051 path_out_count, path_out_count); |
| 111 | 1052 } |
| 1053 else | |
| 1054 { | |
| 1055 /* No copy case. In this case we don't have an equivalent block | |
| 1056 on the duplicated thread path to update, but we do need | |
| 1057 to remove the portion of the counts/freqs that were moved | |
| 1058 to the duplicated path from the counts/freqs flowing through | |
| 1059 this block on the original path. Since all the no-copy edges | |
| 1060 are after any joiner, the removed count is the same as | |
| 1061 path_out_count. | |
| 1062 | |
| 1063 If we didn't have a joiner, then cur_path_freq was the sum | |
| 1064 of the total frequencies along all incoming edges to the | |
| 1065 thread path (path_in_freq). If we had a joiner, it would have | |
| 1066 been updated at the end of that handling to the edge frequency | |
| 1067 along the duplicated joiner path edge. */ | |
| 131 | 1068 update_profile (epath, NULL, path_out_count, path_out_count); |
| 111 | 1069 } |
| 1070 | |
| 1071 /* Increment the index into the duplicated path when we processed | |
| 1072 a duplicated block. */ | |
| 1073 if ((*path)[i]->type == EDGE_COPY_SRC_JOINER_BLOCK | |
| 1074 || (*path)[i]->type == EDGE_COPY_SRC_BLOCK) | |
| 1075 { | |
| 1076 count++; | |
| 1077 } | |
| 1078 } | |
| 1079 } | |
| 1080 | |
| 0 | 1081 /* Hash table traversal callback routine to create duplicate blocks. */ |
| 1082 | |
| 111 | 1083 int |
| 1084 ssa_create_duplicates (struct redirection_data **slot, | |
| 1085 ssa_local_info_t *local_info) | |
| 0 | 1086 { |
| 111 | 1087 struct redirection_data *rd = *slot; |
| 1088 | |
| 1089 /* The second duplicated block in a jump threading path is specific | |
| 1090 to the path. So it gets stored in RD rather than in LOCAL_DATA. | |
| 1091 | |
| 1092 Each time we're called, we have to look through the path and see | |
| 1093 if a second block needs to be duplicated. | |
| 1094 | |
| 1095 Note the search starts with the third edge on the path. The first | |
| 1096 edge is the incoming edge, the second edge always has its source | |
| 1097 duplicated. Thus we start our search with the third edge. */ | |
| 1098 vec<jump_thread_edge *> *path = rd->path; | |
| 1099 for (unsigned int i = 2; i < path->length (); i++) | |
| 1100 { | |
| 1101 if ((*path)[i]->type == EDGE_COPY_SRC_BLOCK | |
| 1102 || (*path)[i]->type == EDGE_COPY_SRC_JOINER_BLOCK) | |
| 1103 { | |
| 1104 create_block_for_threading ((*path)[i]->e->src, rd, 1, | |
| 1105 &local_info->duplicate_blocks); | |
| 1106 break; | |
| 1107 } | |
| 1108 } | |
| 0 | 1109 |
| 1110 /* Create a template block if we have not done so already. Otherwise | |
| 1111 use the template to create a new block. */ | |
| 1112 if (local_info->template_block == NULL) | |
| 1113 { | |
| 111 | 1114 create_block_for_threading ((*path)[1]->e->src, rd, 0, |
| 1115 &local_info->duplicate_blocks); | |
| 1116 local_info->template_block = rd->dup_blocks[0]; | |
| 0 | 1117 |
| 1118 /* We do not create any outgoing edges for the template. We will | |
| 1119 take care of that in a later traversal. That way we do not | |
| 1120 create edges that are going to just be deleted. */ | |
| 1121 } | |
| 1122 else | |
| 1123 { | |
| 111 | 1124 create_block_for_threading (local_info->template_block, rd, 0, |
| 1125 &local_info->duplicate_blocks); | |
| 0 | 1126 |
| 1127 /* Go ahead and wire up outgoing edges and update PHIs for the duplicate | |
| 111 | 1128 block. */ |
| 1129 ssa_fix_duplicate_block_edges (rd, local_info); | |
| 0 | 1130 } |
| 1131 | |
| 1132 /* Keep walking the hash table. */ | |
| 1133 return 1; | |
| 1134 } | |
| 1135 | |
| 1136 /* We did not create any outgoing edges for the template block during | |
| 1137 block creation. This hash table traversal callback creates the | |
| 1138 outgoing edge for the template block. */ | |
| 1139 | |
| 111 | 1140 inline int |
| 1141 ssa_fixup_template_block (struct redirection_data **slot, | |
| 1142 ssa_local_info_t *local_info) | |
| 0 | 1143 { |
| 111 | 1144 struct redirection_data *rd = *slot; |
| 1145 | |
| 1146 /* If this is the template block halt the traversal after updating | |
| 1147 it appropriately. | |
| 1148 | |
| 1149 If we were threading through an joiner block, then we want | |
| 1150 to keep its control statement and redirect an outgoing edge. | |
| 1151 Else we want to remove the control statement & edges, then create | |
| 1152 a new outgoing edge. In both cases we may need to update PHIs. */ | |
| 1153 if (rd->dup_blocks[0] && rd->dup_blocks[0] == local_info->template_block) | |
| 0 | 1154 { |
| 111 | 1155 ssa_fix_duplicate_block_edges (rd, local_info); |
| 0 | 1156 return 0; |
| 1157 } | |
| 1158 | |
| 1159 return 1; | |
| 1160 } | |
| 1161 | |
| 1162 /* Hash table traversal callback to redirect each incoming edge | |
| 1163 associated with this hash table element to its new destination. */ | |
| 1164 | |
| 111 | 1165 int |
| 1166 ssa_redirect_edges (struct redirection_data **slot, | |
| 1167 ssa_local_info_t *local_info) | |
| 0 | 1168 { |
| 111 | 1169 struct redirection_data *rd = *slot; |
| 0 | 1170 struct el *next, *el; |
| 1171 | |
| 111 | 1172 /* Walk over all the incoming edges associated with this hash table |
| 1173 entry. */ | |
| 0 | 1174 for (el = rd->incoming_edges; el; el = next) |
| 1175 { | |
| 1176 edge e = el->e; | |
| 111 | 1177 vec<jump_thread_edge *> *path = THREAD_PATH (e); |
| 0 | 1178 |
| 1179 /* Go ahead and free this element from the list. Doing this now | |
| 1180 avoids the need for another list walk when we destroy the hash | |
| 1181 table. */ | |
| 1182 next = el->next; | |
| 1183 free (el); | |
| 1184 | |
| 1185 thread_stats.num_threaded_edges++; | |
| 1186 | |
| 111 | 1187 if (rd->dup_blocks[0]) |
| 0 | 1188 { |
| 1189 edge e2; | |
| 1190 | |
| 1191 if (dump_file && (dump_flags & TDF_DETAILS)) | |
| 1192 fprintf (dump_file, " Threaded jump %d --> %d to %d\n", | |
| 111 | 1193 e->src->index, e->dest->index, rd->dup_blocks[0]->index); |
| 1194 | |
| 1195 /* Redirect the incoming edge (possibly to the joiner block) to the | |
| 1196 appropriate duplicate block. */ | |
| 1197 e2 = redirect_edge_and_branch (e, rd->dup_blocks[0]); | |
| 0 | 1198 gcc_assert (e == e2); |
| 1199 flush_pending_stmts (e2); | |
| 1200 } | |
| 111 | 1201 |
| 1202 /* Go ahead and clear E->aux. It's not needed anymore and failure | |
| 1203 to clear it will cause all kinds of unpleasant problems later. */ | |
| 1204 delete_jump_thread_path (path); | |
| 1205 e->aux = NULL; | |
| 1206 | |
| 0 | 1207 } |
| 1208 | |
| 1209 /* Indicate that we actually threaded one or more jumps. */ | |
| 1210 if (rd->incoming_edges) | |
| 1211 local_info->jumps_threaded = true; | |
| 1212 | |
| 1213 return 1; | |
| 1214 } | |
| 1215 | |
| 1216 /* Return true if this block has no executable statements other than | |
| 1217 a simple ctrl flow instruction. When the number of outgoing edges | |
| 1218 is one, this is equivalent to a "forwarder" block. */ | |
| 1219 | |
| 1220 static bool | |
| 1221 redirection_block_p (basic_block bb) | |
| 1222 { | |
| 1223 gimple_stmt_iterator gsi; | |
| 1224 | |
| 1225 /* Advance to the first executable statement. */ | |
| 1226 gsi = gsi_start_bb (bb); | |
| 1227 while (!gsi_end_p (gsi) | |
| 111 | 1228 && (gimple_code (gsi_stmt (gsi)) == GIMPLE_LABEL |
|
55
77e2b8dfacca
update it from 4.4.3 to 4.5.0
ryoma <e075725@ie.u-ryukyu.ac.jp>
parents:
0
diff
changeset
|
1229 || is_gimple_debug (gsi_stmt (gsi)) |
| 111 | 1230 || gimple_nop_p (gsi_stmt (gsi)) |
| 1231 || gimple_clobber_p (gsi_stmt (gsi)))) | |
| 0 | 1232 gsi_next (&gsi); |
|
55
77e2b8dfacca
update it from 4.4.3 to 4.5.0
ryoma <e075725@ie.u-ryukyu.ac.jp>
parents:
0
diff
changeset
|
1233 |
| 0 | 1234 /* Check if this is an empty block. */ |
| 1235 if (gsi_end_p (gsi)) | |
| 1236 return true; | |
| 1237 | |
| 1238 /* Test that we've reached the terminating control statement. */ | |
| 1239 return gsi_stmt (gsi) | |
| 111 | 1240 && (gimple_code (gsi_stmt (gsi)) == GIMPLE_COND |
| 1241 || gimple_code (gsi_stmt (gsi)) == GIMPLE_GOTO | |
| 1242 || gimple_code (gsi_stmt (gsi)) == GIMPLE_SWITCH); | |
| 0 | 1243 } |
| 1244 | |
| 1245 /* BB is a block which ends with a COND_EXPR or SWITCH_EXPR and when BB | |
| 1246 is reached via one or more specific incoming edges, we know which | |
| 1247 outgoing edge from BB will be traversed. | |
| 1248 | |
| 1249 We want to redirect those incoming edges to the target of the | |
| 1250 appropriate outgoing edge. Doing so avoids a conditional branch | |
| 1251 and may expose new optimization opportunities. Note that we have | |
| 1252 to update dominator tree and SSA graph after such changes. | |
| 1253 | |
| 1254 The key to keeping the SSA graph update manageable is to duplicate | |
| 1255 the side effects occurring in BB so that those side effects still | |
| 1256 occur on the paths which bypass BB after redirecting edges. | |
| 1257 | |
| 1258 We accomplish this by creating duplicates of BB and arranging for | |
| 1259 the duplicates to unconditionally pass control to one specific | |
| 1260 successor of BB. We then revector the incoming edges into BB to | |
| 1261 the appropriate duplicate of BB. | |
| 1262 | |
| 1263 If NOLOOP_ONLY is true, we only perform the threading as long as it | |
| 111 | 1264 does not affect the structure of the loops in a nontrivial way. |
| 1265 | |
| 1266 If JOINERS is true, then thread through joiner blocks as well. */ | |
| 0 | 1267 |
| 1268 static bool | |
| 111 | 1269 thread_block_1 (basic_block bb, bool noloop_only, bool joiners) |
| 0 | 1270 { |
| 1271 /* E is an incoming edge into BB that we may or may not want to | |
| 1272 redirect to a duplicate of BB. */ | |
| 1273 edge e, e2; | |
| 1274 edge_iterator ei; | |
| 111 | 1275 ssa_local_info_t local_info; |
| 1276 | |
| 1277 local_info.duplicate_blocks = BITMAP_ALLOC (NULL); | |
| 1278 local_info.need_profile_correction = false; | |
| 0 | 1279 |
| 1280 /* To avoid scanning a linear array for the element we need we instead | |
| 1281 use a hash table. For normal code there should be no noticeable | |
| 1282 difference. However, if we have a block with a large number of | |
| 1283 incoming and outgoing edges such linear searches can get expensive. */ | |
| 111 | 1284 redirection_data |
| 1285 = new hash_table<struct redirection_data> (EDGE_COUNT (bb->succs)); | |
| 0 | 1286 |
| 1287 /* Record each unique threaded destination into a hash table for | |
| 1288 efficient lookups. */ | |
| 111 | 1289 edge last = NULL; |
| 0 | 1290 FOR_EACH_EDGE (e, ei, bb->preds) |
| 1291 { | |
| 111 | 1292 if (e->aux == NULL) |
| 1293 continue; | |
| 1294 | |
| 1295 vec<jump_thread_edge *> *path = THREAD_PATH (e); | |
| 1296 | |
| 1297 if (((*path)[1]->type == EDGE_COPY_SRC_JOINER_BLOCK && !joiners) | |
| 1298 || ((*path)[1]->type == EDGE_COPY_SRC_BLOCK && joiners)) | |
| 1299 continue; | |
| 1300 | |
| 1301 e2 = path->last ()->e; | |
| 1302 if (!e2 || noloop_only) | |
| 1303 { | |
| 0 | 1304 /* If NOLOOP_ONLY is true, we only allow threading through the |
| 1305 header of a loop to exit edges. */ | |
| 111 | 1306 |
| 1307 /* One case occurs when there was loop header buried in a jump | |
| 1308 threading path that crosses loop boundaries. We do not try | |
| 1309 and thread this elsewhere, so just cancel the jump threading | |
| 1310 request by clearing the AUX field now. */ | |
| 1311 if (bb->loop_father != e2->src->loop_father | |
| 131 | 1312 && (!loop_exit_edge_p (e2->src->loop_father, e2) |
| 1313 || flow_loop_nested_p (bb->loop_father, | |
| 1314 e2->dest->loop_father))) | |
| 111 | 1315 { |
| 1316 /* Since this case is not handled by our special code | |
| 1317 to thread through a loop header, we must explicitly | |
| 1318 cancel the threading request here. */ | |
| 1319 delete_jump_thread_path (path); | |
| 1320 e->aux = NULL; | |
| 1321 continue; | |
| 1322 } | |
| 1323 | |
| 1324 /* Another case occurs when trying to thread through our | |
| 1325 own loop header, possibly from inside the loop. We will | |
| 1326 thread these later. */ | |
| 1327 unsigned int i; | |
| 1328 for (i = 1; i < path->length (); i++) | |
| 1329 { | |
| 1330 if ((*path)[i]->e->src == bb->loop_father->header | |
| 1331 && (!loop_exit_edge_p (bb->loop_father, e2) | |
| 1332 || (*path)[1]->type == EDGE_COPY_SRC_JOINER_BLOCK)) | |
| 1333 break; | |
| 1334 } | |
| 1335 | |
| 1336 if (i != path->length ()) | |
| 1337 continue; | |
| 131 | 1338 |
| 1339 /* Loop parallelization can be confused by the result of | |
| 1340 threading through the loop exit test back into the loop. | |
| 1341 However, theading those jumps seems to help other codes. | |
| 1342 | |
| 1343 I have been unable to find anything related to the shape of | |
| 1344 the CFG, the contents of the affected blocks, etc which would | |
| 1345 allow a more sensible test than what we're using below which | |
| 1346 merely avoids the optimization when parallelizing loops. */ | |
| 1347 if (flag_tree_parallelize_loops > 1) | |
| 1348 { | |
| 1349 for (i = 1; i < path->length (); i++) | |
| 1350 if (bb->loop_father == e2->src->loop_father | |
| 1351 && loop_exits_from_bb_p (bb->loop_father, | |
| 1352 (*path)[i]->e->src) | |
| 1353 && !loop_exit_edge_p (bb->loop_father, e2)) | |
| 1354 break; | |
| 1355 | |
| 1356 if (i != path->length ()) | |
| 1357 { | |
| 1358 delete_jump_thread_path (path); | |
| 1359 e->aux = NULL; | |
| 1360 continue; | |
| 1361 } | |
| 1362 } | |
| 0 | 1363 } |
| 1364 | |
| 1365 /* Insert the outgoing edge into the hash table if it is not | |
| 1366 already in the hash table. */ | |
| 111 | 1367 lookup_redirection_data (e, INSERT); |
| 1368 | |
| 1369 /* When we have thread paths through a common joiner with different | |
| 1370 final destinations, then we may need corrections to deal with | |
| 1371 profile insanities. See the big comment before compute_path_counts. */ | |
| 1372 if ((*path)[1]->type == EDGE_COPY_SRC_JOINER_BLOCK) | |
| 1373 { | |
| 1374 if (!last) | |
| 1375 last = e2; | |
| 1376 else if (e2 != last) | |
| 1377 local_info.need_profile_correction = true; | |
| 1378 } | |
| 0 | 1379 } |
| 1380 | |
| 1381 /* We do not update dominance info. */ | |
| 1382 free_dominance_info (CDI_DOMINATORS); | |
| 1383 | |
| 111 | 1384 /* We know we only thread through the loop header to loop exits. |
| 1385 Let the basic block duplication hook know we are not creating | |
| 1386 a multiple entry loop. */ | |
| 1387 if (noloop_only | |
| 1388 && bb == bb->loop_father->header) | |
| 1389 set_loop_copy (bb->loop_father, loop_outer (bb->loop_father)); | |
| 1390 | |
| 0 | 1391 /* Now create duplicates of BB. |
| 1392 | |
| 1393 Note that for a block with a high outgoing degree we can waste | |
| 1394 a lot of time and memory creating and destroying useless edges. | |
| 1395 | |
| 1396 So we first duplicate BB and remove the control structure at the | |
| 1397 tail of the duplicate as well as all outgoing edges from the | |
| 1398 duplicate. We then use that duplicate block as a template for | |
| 1399 the rest of the duplicates. */ | |
| 1400 local_info.template_block = NULL; | |
| 1401 local_info.bb = bb; | |
| 1402 local_info.jumps_threaded = false; | |
| 111 | 1403 redirection_data->traverse <ssa_local_info_t *, ssa_create_duplicates> |
| 1404 (&local_info); | |
| 0 | 1405 |
| 1406 /* The template does not have an outgoing edge. Create that outgoing | |
| 1407 edge and update PHI nodes as the edge's target as necessary. | |
| 1408 | |
| 1409 We do this after creating all the duplicates to avoid creating | |
| 1410 unnecessary edges. */ | |
| 111 | 1411 redirection_data->traverse <ssa_local_info_t *, ssa_fixup_template_block> |
| 1412 (&local_info); | |
| 0 | 1413 |
| 1414 /* The hash table traversals above created the duplicate blocks (and the | |
| 1415 statements within the duplicate blocks). This loop creates PHI nodes for | |
| 1416 the duplicated blocks and redirects the incoming edges into BB to reach | |
| 1417 the duplicates of BB. */ | |
| 111 | 1418 redirection_data->traverse <ssa_local_info_t *, ssa_redirect_edges> |
| 1419 (&local_info); | |
| 0 | 1420 |
| 1421 /* Done with this block. Clear REDIRECTION_DATA. */ | |
| 111 | 1422 delete redirection_data; |
| 0 | 1423 redirection_data = NULL; |
| 1424 | |
| 111 | 1425 if (noloop_only |
| 1426 && bb == bb->loop_father->header) | |
| 1427 set_loop_copy (bb->loop_father, NULL); | |
| 1428 | |
| 1429 BITMAP_FREE (local_info.duplicate_blocks); | |
| 1430 local_info.duplicate_blocks = NULL; | |
| 1431 | |
| 0 | 1432 /* Indicate to our caller whether or not any jumps were threaded. */ |
| 1433 return local_info.jumps_threaded; | |
| 1434 } | |
| 1435 | |
| 111 | 1436 /* Wrapper for thread_block_1 so that we can first handle jump |
| 1437 thread paths which do not involve copying joiner blocks, then | |
| 1438 handle jump thread paths which have joiner blocks. | |
| 1439 | |
| 1440 By doing things this way we can be as aggressive as possible and | |
| 1441 not worry that copying a joiner block will create a jump threading | |
| 1442 opportunity. */ | |
| 1443 | |
| 1444 static bool | |
| 1445 thread_block (basic_block bb, bool noloop_only) | |
| 0 | 1446 { |
| 111 | 1447 bool retval; |
| 1448 retval = thread_block_1 (bb, noloop_only, false); | |
| 1449 retval |= thread_block_1 (bb, noloop_only, true); | |
| 1450 return retval; | |
| 0 | 1451 } |
| 1452 | |
| 1453 /* Callback for dfs_enumerate_from. Returns true if BB is different | |
| 1454 from STOP and DBDS_CE_STOP. */ | |
| 1455 | |
| 1456 static basic_block dbds_ce_stop; | |
| 1457 static bool | |
| 1458 dbds_continue_enumeration_p (const_basic_block bb, const void *stop) | |
| 1459 { | |
| 1460 return (bb != (const_basic_block) stop | |
| 1461 && bb != dbds_ce_stop); | |
| 1462 } | |
| 1463 | |
| 1464 /* Evaluates the dominance relationship of latch of the LOOP and BB, and | |
| 1465 returns the state. */ | |
| 1466 | |
| 1467 enum bb_dom_status | |
| 1468 determine_bb_domination_status (struct loop *loop, basic_block bb) | |
| 1469 { | |
| 1470 basic_block *bblocks; | |
| 1471 unsigned nblocks, i; | |
| 1472 bool bb_reachable = false; | |
| 1473 edge_iterator ei; | |
| 1474 edge e; | |
| 1475 | |
| 111 | 1476 /* This function assumes BB is a successor of LOOP->header. |
| 1477 If that is not the case return DOMST_NONDOMINATING which | |
| 1478 is always safe. */ | |
| 0 | 1479 { |
| 1480 bool ok = false; | |
| 1481 | |
| 1482 FOR_EACH_EDGE (e, ei, bb->preds) | |
| 1483 { | |
| 1484 if (e->src == loop->header) | |
| 1485 { | |
| 1486 ok = true; | |
| 1487 break; | |
| 1488 } | |
| 1489 } | |
| 1490 | |
| 111 | 1491 if (!ok) |
| 1492 return DOMST_NONDOMINATING; | |
| 0 | 1493 } |
| 1494 | |
| 1495 if (bb == loop->latch) | |
| 1496 return DOMST_DOMINATING; | |
| 1497 | |
| 1498 /* Check that BB dominates LOOP->latch, and that it is back-reachable | |
| 1499 from it. */ | |
| 1500 | |
| 1501 bblocks = XCNEWVEC (basic_block, loop->num_nodes); | |
| 1502 dbds_ce_stop = loop->header; | |
| 1503 nblocks = dfs_enumerate_from (loop->latch, 1, dbds_continue_enumeration_p, | |
| 1504 bblocks, loop->num_nodes, bb); | |
| 1505 for (i = 0; i < nblocks; i++) | |
| 1506 FOR_EACH_EDGE (e, ei, bblocks[i]->preds) | |
| 1507 { | |
| 1508 if (e->src == loop->header) | |
| 1509 { | |
| 1510 free (bblocks); | |
| 1511 return DOMST_NONDOMINATING; | |
| 1512 } | |
| 1513 if (e->src == bb) | |
| 1514 bb_reachable = true; | |
| 1515 } | |
| 1516 | |
| 1517 free (bblocks); | |
| 1518 return (bb_reachable ? DOMST_DOMINATING : DOMST_LOOP_BROKEN); | |
| 1519 } | |
| 1520 | |
| 1521 /* Thread jumps through the header of LOOP. Returns true if cfg changes. | |
| 1522 If MAY_PEEL_LOOP_HEADERS is false, we avoid threading from entry edges | |
| 1523 to the inside of the loop. */ | |
| 1524 | |
| 1525 static bool | |
| 1526 thread_through_loop_header (struct loop *loop, bool may_peel_loop_headers) | |
| 1527 { | |
| 1528 basic_block header = loop->header; | |
| 1529 edge e, tgt_edge, latch = loop_latch_edge (loop); | |
| 1530 edge_iterator ei; | |
| 1531 basic_block tgt_bb, atgt_bb; | |
| 1532 enum bb_dom_status domst; | |
| 1533 | |
| 1534 /* We have already threaded through headers to exits, so all the threading | |
| 1535 requests now are to the inside of the loop. We need to avoid creating | |
| 1536 irreducible regions (i.e., loops with more than one entry block), and | |
| 1537 also loop with several latch edges, or new subloops of the loop (although | |
| 1538 there are cases where it might be appropriate, it is difficult to decide, | |
| 1539 and doing it wrongly may confuse other optimizers). | |
| 1540 | |
| 1541 We could handle more general cases here. However, the intention is to | |
| 1542 preserve some information about the loop, which is impossible if its | |
| 1543 structure changes significantly, in a way that is not well understood. | |
| 1544 Thus we only handle few important special cases, in which also updating | |
| 1545 of the loop-carried information should be feasible: | |
| 1546 | |
| 1547 1) Propagation of latch edge to a block that dominates the latch block | |
| 1548 of a loop. This aims to handle the following idiom: | |
| 1549 | |
| 1550 first = 1; | |
| 1551 while (1) | |
| 1552 { | |
| 1553 if (first) | |
| 1554 initialize; | |
| 1555 first = 0; | |
| 1556 body; | |
| 1557 } | |
| 1558 | |
| 1559 After threading the latch edge, this becomes | |
| 1560 | |
| 1561 first = 1; | |
| 1562 if (first) | |
| 1563 initialize; | |
| 1564 while (1) | |
| 1565 { | |
| 1566 first = 0; | |
| 1567 body; | |
| 1568 } | |
| 1569 | |
| 1570 The original header of the loop is moved out of it, and we may thread | |
| 1571 the remaining edges through it without further constraints. | |
| 1572 | |
| 1573 2) All entry edges are propagated to a single basic block that dominates | |
| 1574 the latch block of the loop. This aims to handle the following idiom | |
| 1575 (normally created for "for" loops): | |
| 1576 | |
| 1577 i = 0; | |
| 1578 while (1) | |
| 1579 { | |
| 1580 if (i >= 100) | |
| 1581 break; | |
| 1582 body; | |
| 1583 i++; | |
| 1584 } | |
| 1585 | |
| 1586 This becomes | |
| 1587 | |
| 1588 i = 0; | |
| 1589 while (1) | |
| 1590 { | |
| 1591 body; | |
| 1592 i++; | |
| 1593 if (i >= 100) | |
| 1594 break; | |
| 1595 } | |
| 1596 */ | |
| 1597 | |
| 1598 /* Threading through the header won't improve the code if the header has just | |
| 1599 one successor. */ | |
| 1600 if (single_succ_p (header)) | |
| 1601 goto fail; | |
| 1602 | |
| 111 | 1603 if (!may_peel_loop_headers && !redirection_block_p (loop->header)) |
| 0 | 1604 goto fail; |
| 1605 else | |
| 1606 { | |
| 1607 tgt_bb = NULL; | |
| 1608 tgt_edge = NULL; | |
| 1609 FOR_EACH_EDGE (e, ei, header->preds) | |
| 1610 { | |
| 1611 if (!e->aux) | |
| 1612 { | |
| 1613 if (e == latch) | |
| 1614 continue; | |
| 1615 | |
| 1616 /* If latch is not threaded, and there is a header | |
| 1617 edge that is not threaded, we would create loop | |
| 1618 with multiple entries. */ | |
| 1619 goto fail; | |
| 1620 } | |
| 1621 | |
| 111 | 1622 vec<jump_thread_edge *> *path = THREAD_PATH (e); |
| 1623 | |
| 1624 if ((*path)[1]->type == EDGE_COPY_SRC_JOINER_BLOCK) | |
| 1625 goto fail; | |
| 1626 tgt_edge = (*path)[1]->e; | |
| 0 | 1627 atgt_bb = tgt_edge->dest; |
| 1628 if (!tgt_bb) | |
| 1629 tgt_bb = atgt_bb; | |
| 1630 /* Two targets of threading would make us create loop | |
| 1631 with multiple entries. */ | |
| 1632 else if (tgt_bb != atgt_bb) | |
| 1633 goto fail; | |
| 1634 } | |
| 1635 | |
| 1636 if (!tgt_bb) | |
| 1637 { | |
| 1638 /* There are no threading requests. */ | |
| 1639 return false; | |
| 1640 } | |
| 1641 | |
| 1642 /* Redirecting to empty loop latch is useless. */ | |
| 1643 if (tgt_bb == loop->latch | |
| 1644 && empty_block_p (loop->latch)) | |
| 1645 goto fail; | |
| 1646 } | |
| 1647 | |
| 1648 /* The target block must dominate the loop latch, otherwise we would be | |
| 1649 creating a subloop. */ | |
| 1650 domst = determine_bb_domination_status (loop, tgt_bb); | |
| 1651 if (domst == DOMST_NONDOMINATING) | |
| 1652 goto fail; | |
| 1653 if (domst == DOMST_LOOP_BROKEN) | |
| 1654 { | |
| 1655 /* If the loop ceased to exist, mark it as such, and thread through its | |
| 1656 original header. */ | |
| 111 | 1657 mark_loop_for_removal (loop); |
| 0 | 1658 return thread_block (header, false); |
| 1659 } | |
| 1660 | |
| 1661 if (tgt_bb->loop_father->header == tgt_bb) | |
| 1662 { | |
| 1663 /* If the target of the threading is a header of a subloop, we need | |
| 1664 to create a preheader for it, so that the headers of the two loops | |
| 1665 do not merge. */ | |
| 1666 if (EDGE_COUNT (tgt_bb->preds) > 2) | |
| 1667 { | |
| 1668 tgt_bb = create_preheader (tgt_bb->loop_father, 0); | |
| 1669 gcc_assert (tgt_bb != NULL); | |
| 1670 } | |
| 1671 else | |
| 1672 tgt_bb = split_edge (tgt_edge); | |
| 1673 } | |
|
55
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update it from 4.4.3 to 4.5.0
ryoma <e075725@ie.u-ryukyu.ac.jp>
parents:
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diff
changeset
|
1674 |
| 111 | 1675 basic_block new_preheader; |
| 1676 | |
| 1677 /* Now consider the case entry edges are redirected to the new entry | |
| 1678 block. Remember one entry edge, so that we can find the new | |
| 1679 preheader (its destination after threading). */ | |
| 1680 FOR_EACH_EDGE (e, ei, header->preds) | |
| 0 | 1681 { |
| 111 | 1682 if (e->aux) |
| 1683 break; | |
| 0 | 1684 } |
|
55
77e2b8dfacca
update it from 4.4.3 to 4.5.0
ryoma <e075725@ie.u-ryukyu.ac.jp>
parents:
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diff
changeset
|
1685 |
| 111 | 1686 /* The duplicate of the header is the new preheader of the loop. Ensure |
| 1687 that it is placed correctly in the loop hierarchy. */ | |
| 1688 set_loop_copy (loop, loop_outer (loop)); | |
| 1689 | |
| 1690 thread_block (header, false); | |
| 1691 set_loop_copy (loop, NULL); | |
| 1692 new_preheader = e->dest; | |
| 1693 | |
| 1694 /* Create the new latch block. This is always necessary, as the latch | |
| 1695 must have only a single successor, but the original header had at | |
| 1696 least two successors. */ | |
| 1697 loop->latch = NULL; | |
| 1698 mfb_kj_edge = single_succ_edge (new_preheader); | |
| 1699 loop->header = mfb_kj_edge->dest; | |
| 1700 latch = make_forwarder_block (tgt_bb, mfb_keep_just, NULL); | |
| 1701 loop->header = latch->dest; | |
| 1702 loop->latch = latch->src; | |
| 0 | 1703 return true; |
| 1704 | |
| 1705 fail: | |
| 1706 /* We failed to thread anything. Cancel the requests. */ | |
| 1707 FOR_EACH_EDGE (e, ei, header->preds) | |
| 1708 { | |
| 111 | 1709 vec<jump_thread_edge *> *path = THREAD_PATH (e); |
| 1710 | |
| 1711 if (path) | |
| 1712 { | |
| 1713 delete_jump_thread_path (path); | |
| 1714 e->aux = NULL; | |
| 1715 } | |
| 0 | 1716 } |
| 1717 return false; | |
| 1718 } | |
| 1719 | |
| 111 | 1720 /* E1 and E2 are edges into the same basic block. Return TRUE if the |
| 1721 PHI arguments associated with those edges are equal or there are no | |
| 1722 PHI arguments, otherwise return FALSE. */ | |
| 1723 | |
| 1724 static bool | |
| 1725 phi_args_equal_on_edges (edge e1, edge e2) | |
| 1726 { | |
| 1727 gphi_iterator gsi; | |
| 1728 int indx1 = e1->dest_idx; | |
| 1729 int indx2 = e2->dest_idx; | |
| 1730 | |
| 1731 for (gsi = gsi_start_phis (e1->dest); !gsi_end_p (gsi); gsi_next (&gsi)) | |
| 1732 { | |
| 1733 gphi *phi = gsi.phi (); | |
| 1734 | |
| 1735 if (!operand_equal_p (gimple_phi_arg_def (phi, indx1), | |
| 1736 gimple_phi_arg_def (phi, indx2), 0)) | |
| 1737 return false; | |
| 1738 } | |
| 1739 return true; | |
| 1740 } | |
| 1741 | |
| 131 | 1742 /* Return the number of non-debug statements and non-virtual PHIs in a |
| 1743 block. */ | |
| 1744 | |
| 1745 static unsigned int | |
| 1746 count_stmts_and_phis_in_block (basic_block bb) | |
| 1747 { | |
| 1748 unsigned int num_stmts = 0; | |
| 1749 | |
| 1750 gphi_iterator gpi; | |
| 1751 for (gpi = gsi_start_phis (bb); !gsi_end_p (gpi); gsi_next (&gpi)) | |
| 1752 if (!virtual_operand_p (PHI_RESULT (gpi.phi ()))) | |
| 1753 num_stmts++; | |
| 1754 | |
| 1755 gimple_stmt_iterator gsi; | |
| 1756 for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi)) | |
| 1757 { | |
| 1758 gimple *stmt = gsi_stmt (gsi); | |
| 1759 if (!is_gimple_debug (stmt)) | |
| 1760 num_stmts++; | |
| 1761 } | |
| 1762 | |
| 1763 return num_stmts; | |
| 1764 } | |
| 1765 | |
| 1766 | |
| 0 | 1767 /* Walk through the registered jump threads and convert them into a |
| 1768 form convenient for this pass. | |
| 1769 | |
| 1770 Any block which has incoming edges threaded to outgoing edges | |
| 1771 will have its entry in THREADED_BLOCK set. | |
| 1772 | |
| 1773 Any threaded edge will have its new outgoing edge stored in the | |
| 1774 original edge's AUX field. | |
| 1775 | |
| 1776 This form avoids the need to walk all the edges in the CFG to | |
| 1777 discover blocks which need processing and avoids unnecessary | |
| 1778 hash table lookups to map from threaded edge to new target. */ | |
| 1779 | |
| 1780 static void | |
| 1781 mark_threaded_blocks (bitmap threaded_blocks) | |
| 1782 { | |
| 1783 unsigned int i; | |
| 1784 bitmap_iterator bi; | |
| 111 | 1785 auto_bitmap tmp; |
| 0 | 1786 basic_block bb; |
| 1787 edge e; | |
| 1788 edge_iterator ei; | |
| 1789 | |
| 111 | 1790 /* It is possible to have jump threads in which one is a subpath |
| 1791 of the other. ie, (A, B), (B, C), (C, D) where B is a joiner | |
| 1792 block and (B, C), (C, D) where no joiner block exists. | |
| 1793 | |
| 1794 When this occurs ignore the jump thread request with the joiner | |
| 1795 block. It's totally subsumed by the simpler jump thread request. | |
| 1796 | |
| 1797 This results in less block copying, simpler CFGs. More importantly, | |
| 1798 when we duplicate the joiner block, B, in this case we will create | |
| 1799 a new threading opportunity that we wouldn't be able to optimize | |
| 1800 until the next jump threading iteration. | |
| 1801 | |
| 1802 So first convert the jump thread requests which do not require a | |
| 1803 joiner block. */ | |
| 1804 for (i = 0; i < paths.length (); i++) | |
| 1805 { | |
| 1806 vec<jump_thread_edge *> *path = paths[i]; | |
| 1807 | |
| 131 | 1808 if (path->length () > 1 |
| 1809 && (*path)[1]->type != EDGE_COPY_SRC_JOINER_BLOCK) | |
| 111 | 1810 { |
| 1811 edge e = (*path)[0]->e; | |
| 1812 e->aux = (void *)path; | |
| 1813 bitmap_set_bit (tmp, e->dest->index); | |
| 1814 } | |
| 1815 } | |
| 1816 | |
| 1817 /* Now iterate again, converting cases where we want to thread | |
| 1818 through a joiner block, but only if no other edge on the path | |
| 1819 already has a jump thread attached to it. We do this in two passes, | |
| 1820 to avoid situations where the order in the paths vec can hide overlapping | |
| 1821 threads (the path is recorded on the incoming edge, so we would miss | |
| 1822 cases where the second path starts at a downstream edge on the same | |
| 1823 path). First record all joiner paths, deleting any in the unexpected | |
| 1824 case where there is already a path for that incoming edge. */ | |
| 1825 for (i = 0; i < paths.length ();) | |
| 0 | 1826 { |
| 111 | 1827 vec<jump_thread_edge *> *path = paths[i]; |
| 1828 | |
| 131 | 1829 if (path->length () > 1 |
| 1830 && (*path)[1]->type == EDGE_COPY_SRC_JOINER_BLOCK) | |
| 111 | 1831 { |
| 1832 /* Attach the path to the starting edge if none is yet recorded. */ | |
| 1833 if ((*path)[0]->e->aux == NULL) | |
| 1834 { | |
| 1835 (*path)[0]->e->aux = path; | |
| 1836 i++; | |
| 1837 } | |
| 1838 else | |
| 1839 { | |
| 1840 paths.unordered_remove (i); | |
| 1841 if (dump_file && (dump_flags & TDF_DETAILS)) | |
| 1842 dump_jump_thread_path (dump_file, *path, false); | |
| 1843 delete_jump_thread_path (path); | |
| 1844 } | |
| 1845 } | |
| 1846 else | |
| 1847 { | |
| 1848 i++; | |
| 1849 } | |
| 1850 } | |
| 1851 | |
| 1852 /* Second, look for paths that have any other jump thread attached to | |
| 1853 them, and either finish converting them or cancel them. */ | |
| 1854 for (i = 0; i < paths.length ();) | |
| 1855 { | |
| 1856 vec<jump_thread_edge *> *path = paths[i]; | |
| 1857 edge e = (*path)[0]->e; | |
| 1858 | |
| 131 | 1859 if (path->length () > 1 |
| 1860 && (*path)[1]->type == EDGE_COPY_SRC_JOINER_BLOCK && e->aux == path) | |
| 111 | 1861 { |
| 1862 unsigned int j; | |
| 1863 for (j = 1; j < path->length (); j++) | |
| 1864 if ((*path)[j]->e->aux != NULL) | |
| 1865 break; | |
| 1866 | |
| 1867 /* If we iterated through the entire path without exiting the loop, | |
| 1868 then we are good to go, record it. */ | |
| 1869 if (j == path->length ()) | |
| 1870 { | |
| 1871 bitmap_set_bit (tmp, e->dest->index); | |
| 1872 i++; | |
| 1873 } | |
| 1874 else | |
| 1875 { | |
| 1876 e->aux = NULL; | |
| 1877 paths.unordered_remove (i); | |
| 1878 if (dump_file && (dump_flags & TDF_DETAILS)) | |
| 1879 dump_jump_thread_path (dump_file, *path, false); | |
| 1880 delete_jump_thread_path (path); | |
| 1881 } | |
| 1882 } | |
| 1883 else | |
| 1884 { | |
| 1885 i++; | |
| 1886 } | |
| 0 | 1887 } |
| 1888 | |
| 131 | 1889 /* When optimizing for size, prune all thread paths where statement |
| 1890 duplication is necessary. | |
| 1891 | |
| 1892 We walk the jump thread path looking for copied blocks. There's | |
| 1893 two types of copied blocks. | |
| 1894 | |
| 1895 EDGE_COPY_SRC_JOINER_BLOCK is always copied and thus we will | |
| 1896 cancel the jump threading request when optimizing for size. | |
| 1897 | |
| 1898 EDGE_COPY_SRC_BLOCK which is copied, but some of its statements | |
| 1899 will be killed by threading. If threading does not kill all of | |
| 1900 its statements, then we should cancel the jump threading request | |
| 1901 when optimizing for size. */ | |
| 0 | 1902 if (optimize_function_for_size_p (cfun)) |
| 1903 { | |
| 1904 EXECUTE_IF_SET_IN_BITMAP (tmp, 0, i, bi) | |
| 1905 { | |
| 131 | 1906 FOR_EACH_EDGE (e, ei, BASIC_BLOCK_FOR_FN (cfun, i)->preds) |
| 1907 if (e->aux) | |
| 1908 { | |
| 1909 vec<jump_thread_edge *> *path = THREAD_PATH (e); | |
| 1910 | |
| 1911 unsigned int j; | |
| 1912 for (j = 1; j < path->length (); j++) | |
| 1913 { | |
| 1914 bb = (*path)[j]->e->src; | |
| 1915 if (redirection_block_p (bb)) | |
| 1916 ; | |
| 1917 else if ((*path)[j]->type == EDGE_COPY_SRC_JOINER_BLOCK | |
| 1918 || ((*path)[j]->type == EDGE_COPY_SRC_BLOCK | |
| 1919 && (count_stmts_and_phis_in_block (bb) | |
| 1920 != estimate_threading_killed_stmts (bb)))) | |
| 1921 break; | |
| 1922 } | |
| 1923 | |
| 1924 if (j != path->length ()) | |
| 1925 { | |
| 1926 if (dump_file && (dump_flags & TDF_DETAILS)) | |
| 1927 dump_jump_thread_path (dump_file, *path, 0); | |
| 1928 delete_jump_thread_path (path); | |
| 1929 e->aux = NULL; | |
| 1930 } | |
| 1931 else | |
| 1932 bitmap_set_bit (threaded_blocks, i); | |
| 1933 } | |
| 0 | 1934 } |
| 1935 } | |
| 1936 else | |
| 1937 bitmap_copy (threaded_blocks, tmp); | |
| 1938 | |
| 111 | 1939 /* If we have a joiner block (J) which has two successors S1 and S2 and |
| 1940 we are threading though S1 and the final destination of the thread | |
| 1941 is S2, then we must verify that any PHI nodes in S2 have the same | |
| 1942 PHI arguments for the edge J->S2 and J->S1->...->S2. | |
| 1943 | |
| 1944 We used to detect this prior to registering the jump thread, but | |
| 1945 that prohibits propagation of edge equivalences into non-dominated | |
| 1946 PHI nodes as the equivalency test might occur before propagation. | |
| 1947 | |
| 1948 This must also occur after we truncate any jump threading paths | |
| 1949 as this scenario may only show up after truncation. | |
| 1950 | |
| 1951 This works for now, but will need improvement as part of the FSA | |
| 1952 optimization. | |
| 1953 | |
| 1954 Note since we've moved the thread request data to the edges, | |
| 1955 we have to iterate on those rather than the threaded_edges vector. */ | |
| 1956 EXECUTE_IF_SET_IN_BITMAP (tmp, 0, i, bi) | |
| 1957 { | |
| 1958 bb = BASIC_BLOCK_FOR_FN (cfun, i); | |
| 1959 FOR_EACH_EDGE (e, ei, bb->preds) | |
| 1960 { | |
| 1961 if (e->aux) | |
| 1962 { | |
| 1963 vec<jump_thread_edge *> *path = THREAD_PATH (e); | |
| 1964 bool have_joiner = ((*path)[1]->type == EDGE_COPY_SRC_JOINER_BLOCK); | |
| 1965 | |
| 1966 if (have_joiner) | |
| 1967 { | |
| 1968 basic_block joiner = e->dest; | |
| 1969 edge final_edge = path->last ()->e; | |
| 1970 basic_block final_dest = final_edge->dest; | |
| 1971 edge e2 = find_edge (joiner, final_dest); | |
| 1972 | |
| 1973 if (e2 && !phi_args_equal_on_edges (e2, final_edge)) | |
| 1974 { | |
| 1975 delete_jump_thread_path (path); | |
| 1976 e->aux = NULL; | |
| 1977 } | |
| 1978 } | |
| 1979 } | |
| 1980 } | |
| 1981 } | |
| 1982 | |
| 1983 /* Look for jump threading paths which cross multiple loop headers. | |
| 1984 | |
| 1985 The code to thread through loop headers will change the CFG in ways | |
| 1986 that invalidate the cached loop iteration information. So we must | |
| 1987 detect that case and wipe the cached information. */ | |
| 1988 EXECUTE_IF_SET_IN_BITMAP (tmp, 0, i, bi) | |
| 1989 { | |
| 1990 basic_block bb = BASIC_BLOCK_FOR_FN (cfun, i); | |
| 1991 FOR_EACH_EDGE (e, ei, bb->preds) | |
| 1992 { | |
| 1993 if (e->aux) | |
| 1994 { | |
| 1995 vec<jump_thread_edge *> *path = THREAD_PATH (e); | |
| 1996 | |
| 1997 for (unsigned int i = 0, crossed_headers = 0; | |
| 1998 i < path->length (); | |
| 1999 i++) | |
| 2000 { | |
| 2001 basic_block dest = (*path)[i]->e->dest; | |
| 2002 basic_block src = (*path)[i]->e->src; | |
| 2003 /* If we enter a loop. */ | |
| 2004 if (flow_loop_nested_p (src->loop_father, dest->loop_father)) | |
| 2005 ++crossed_headers; | |
| 2006 /* If we step from a block outside an irreducible region | |
| 2007 to a block inside an irreducible region, then we have | |
| 2008 crossed into a loop. */ | |
| 2009 else if (! (src->flags & BB_IRREDUCIBLE_LOOP) | |
| 2010 && (dest->flags & BB_IRREDUCIBLE_LOOP)) | |
| 2011 ++crossed_headers; | |
| 2012 if (crossed_headers > 1) | |
| 2013 { | |
| 2014 vect_free_loop_info_assumptions | |
| 2015 ((*path)[path->length () - 1]->e->dest->loop_father); | |
| 2016 break; | |
| 2017 } | |
| 2018 } | |
| 2019 } | |
| 2020 } | |
| 2021 } | |
| 2022 } | |
| 2023 | |
| 2024 | |
| 2025 /* Verify that the REGION is a valid jump thread. A jump thread is a special | |
| 2026 case of SEME Single Entry Multiple Exits region in which all nodes in the | |
| 2027 REGION have exactly one incoming edge. The only exception is the first block | |
| 2028 that may not have been connected to the rest of the cfg yet. */ | |
| 2029 | |
| 2030 DEBUG_FUNCTION void | |
| 2031 verify_jump_thread (basic_block *region, unsigned n_region) | |
| 2032 { | |
| 2033 for (unsigned i = 0; i < n_region; i++) | |
| 2034 gcc_assert (EDGE_COUNT (region[i]->preds) <= 1); | |
| 2035 } | |
| 2036 | |
| 2037 /* Return true when BB is one of the first N items in BBS. */ | |
| 2038 | |
| 2039 static inline bool | |
| 2040 bb_in_bbs (basic_block bb, basic_block *bbs, int n) | |
| 2041 { | |
| 2042 for (int i = 0; i < n; i++) | |
| 2043 if (bb == bbs[i]) | |
| 2044 return true; | |
| 2045 | |
| 2046 return false; | |
| 0 | 2047 } |
| 2048 | |
| 131 | 2049 DEBUG_FUNCTION void |
| 2050 debug_path (FILE *dump_file, int pathno) | |
| 2051 { | |
| 2052 vec<jump_thread_edge *> *p = paths[pathno]; | |
| 2053 fprintf (dump_file, "path: "); | |
| 2054 for (unsigned i = 0; i < p->length (); ++i) | |
| 2055 fprintf (dump_file, "%d -> %d, ", | |
| 2056 (*p)[i]->e->src->index, (*p)[i]->e->dest->index); | |
| 2057 fprintf (dump_file, "\n"); | |
| 2058 } | |
| 2059 | |
| 2060 DEBUG_FUNCTION void | |
| 2061 debug_all_paths () | |
| 2062 { | |
| 2063 for (unsigned i = 0; i < paths.length (); ++i) | |
| 2064 debug_path (stderr, i); | |
| 2065 } | |
| 2066 | |
| 2067 /* Rewire a jump_thread_edge so that the source block is now a | |
| 2068 threaded source block. | |
| 2069 | |
| 2070 PATH_NUM is an index into the global path table PATHS. | |
| 2071 EDGE_NUM is the jump thread edge number into said path. | |
| 2072 | |
| 2073 Returns TRUE if we were able to successfully rewire the edge. */ | |
| 2074 | |
| 2075 static bool | |
| 2076 rewire_first_differing_edge (unsigned path_num, unsigned edge_num) | |
| 2077 { | |
| 2078 vec<jump_thread_edge *> *path = paths[path_num]; | |
| 2079 edge &e = (*path)[edge_num]->e; | |
| 2080 if (dump_file && (dump_flags & TDF_DETAILS)) | |
| 2081 fprintf (dump_file, "rewiring edge candidate: %d -> %d\n", | |
| 2082 e->src->index, e->dest->index); | |
| 2083 basic_block src_copy = get_bb_copy (e->src); | |
| 2084 if (src_copy == NULL) | |
| 2085 { | |
| 2086 if (dump_file && (dump_flags & TDF_DETAILS)) | |
| 2087 fprintf (dump_file, "ignoring candidate: there is no src COPY\n"); | |
| 2088 return false; | |
| 2089 } | |
| 2090 edge new_edge = find_edge (src_copy, e->dest); | |
| 2091 /* If the previously threaded paths created a flow graph where we | |
| 2092 can no longer figure out where to go, give up. */ | |
| 2093 if (new_edge == NULL) | |
| 2094 { | |
| 2095 if (dump_file && (dump_flags & TDF_DETAILS)) | |
| 2096 fprintf (dump_file, "ignoring candidate: we lost our way\n"); | |
| 2097 return false; | |
| 2098 } | |
| 2099 e = new_edge; | |
| 2100 return true; | |
| 2101 } | |
| 2102 | |
| 2103 /* After an FSM path has been jump threaded, adjust the remaining FSM | |
| 2104 paths that are subsets of this path, so these paths can be safely | |
| 2105 threaded within the context of the new threaded path. | |
| 2106 | |
| 2107 For example, suppose we have just threaded: | |
| 2108 | |
| 2109 5 -> 6 -> 7 -> 8 -> 12 => 5 -> 6' -> 7' -> 8' -> 12' | |
| 2110 | |
| 2111 And we have an upcoming threading candidate: | |
| 2112 5 -> 6 -> 7 -> 8 -> 15 -> 20 | |
| 2113 | |
| 2114 This function adjusts the upcoming path into: | |
| 2115 8' -> 15 -> 20 | |
| 2116 | |
| 2117 CURR_PATH_NUM is an index into the global paths table. It | |
| 2118 specifies the path that was just threaded. */ | |
| 2119 | |
| 2120 static void | |
| 2121 adjust_paths_after_duplication (unsigned curr_path_num) | |
| 2122 { | |
| 2123 vec<jump_thread_edge *> *curr_path = paths[curr_path_num]; | |
| 2124 gcc_assert ((*curr_path)[0]->type == EDGE_FSM_THREAD); | |
| 2125 | |
| 2126 if (dump_file && (dump_flags & TDF_DETAILS)) | |
| 2127 { | |
| 2128 fprintf (dump_file, "just threaded: "); | |
| 2129 debug_path (dump_file, curr_path_num); | |
| 2130 } | |
| 2131 | |
| 2132 /* Iterate through all the other paths and adjust them. */ | |
| 2133 for (unsigned cand_path_num = 0; cand_path_num < paths.length (); ) | |
| 2134 { | |
| 2135 if (cand_path_num == curr_path_num) | |
| 2136 { | |
| 2137 ++cand_path_num; | |
| 2138 continue; | |
| 2139 } | |
| 2140 /* Make sure the candidate to adjust starts with the same path | |
| 2141 as the recently threaded path and is an FSM thread. */ | |
| 2142 vec<jump_thread_edge *> *cand_path = paths[cand_path_num]; | |
| 2143 if ((*cand_path)[0]->type != EDGE_FSM_THREAD | |
| 2144 || (*cand_path)[0]->e != (*curr_path)[0]->e) | |
| 2145 { | |
| 2146 ++cand_path_num; | |
| 2147 continue; | |
| 2148 } | |
| 2149 if (dump_file && (dump_flags & TDF_DETAILS)) | |
| 2150 { | |
| 2151 fprintf (dump_file, "adjusting candidate: "); | |
| 2152 debug_path (dump_file, cand_path_num); | |
| 2153 } | |
| 2154 | |
| 2155 /* Chop off from the candidate path any prefix it shares with | |
| 2156 the recently threaded path. */ | |
| 2157 unsigned minlength = MIN (curr_path->length (), cand_path->length ()); | |
| 2158 unsigned j; | |
| 2159 for (j = 0; j < minlength; ++j) | |
| 2160 { | |
| 2161 edge cand_edge = (*cand_path)[j]->e; | |
| 2162 edge curr_edge = (*curr_path)[j]->e; | |
| 2163 | |
| 2164 /* Once the prefix no longer matches, adjust the first | |
| 2165 non-matching edge to point from an adjusted edge to | |
| 2166 wherever it was going. */ | |
| 2167 if (cand_edge != curr_edge) | |
| 2168 { | |
| 2169 gcc_assert (cand_edge->src == curr_edge->src); | |
| 2170 if (!rewire_first_differing_edge (cand_path_num, j)) | |
| 2171 goto remove_candidate_from_list; | |
| 2172 break; | |
| 2173 } | |
| 2174 } | |
| 2175 if (j == minlength) | |
| 2176 { | |
| 2177 /* If we consumed the max subgraph we could look at, and | |
| 2178 still didn't find any different edges, it's the | |
| 2179 last edge after MINLENGTH. */ | |
| 2180 if (cand_path->length () > minlength) | |
| 2181 { | |
| 2182 if (!rewire_first_differing_edge (cand_path_num, j)) | |
| 2183 goto remove_candidate_from_list; | |
| 2184 } | |
| 2185 else if (dump_file && (dump_flags & TDF_DETAILS)) | |
| 2186 fprintf (dump_file, "adjusting first edge after MINLENGTH.\n"); | |
| 2187 } | |
| 2188 if (j > 0) | |
| 2189 { | |
| 2190 /* If we are removing everything, delete the entire candidate. */ | |
| 2191 if (j == cand_path->length ()) | |
| 2192 { | |
| 2193 remove_candidate_from_list: | |
| 2194 if (dump_file && (dump_flags & TDF_DETAILS)) | |
| 2195 fprintf (dump_file, "adjusted candidate: [EMPTY]\n"); | |
| 2196 delete_jump_thread_path (cand_path); | |
| 2197 paths.unordered_remove (cand_path_num); | |
| 2198 continue; | |
| 2199 } | |
| 2200 /* Otherwise, just remove the redundant sub-path. */ | |
| 2201 cand_path->block_remove (0, j); | |
| 2202 } | |
| 2203 if (dump_file && (dump_flags & TDF_DETAILS)) | |
| 2204 { | |
| 2205 fprintf (dump_file, "adjusted candidate: "); | |
| 2206 debug_path (dump_file, cand_path_num); | |
| 2207 } | |
| 2208 ++cand_path_num; | |
| 2209 } | |
| 2210 } | |
| 2211 | |
| 111 | 2212 /* Duplicates a jump-thread path of N_REGION basic blocks. |
| 2213 The ENTRY edge is redirected to the duplicate of the region. | |
| 2214 | |
| 2215 Remove the last conditional statement in the last basic block in the REGION, | |
| 2216 and create a single fallthru edge pointing to the same destination as the | |
| 2217 EXIT edge. | |
| 2218 | |
| 131 | 2219 CURRENT_PATH_NO is an index into the global paths[] table |
| 2220 specifying the jump-thread path. | |
| 2221 | |
| 111 | 2222 Returns false if it is unable to copy the region, true otherwise. */ |
| 2223 | |
| 2224 static bool | |
| 2225 duplicate_thread_path (edge entry, edge exit, basic_block *region, | |
| 131 | 2226 unsigned n_region, unsigned current_path_no) |
| 111 | 2227 { |
| 2228 unsigned i; | |
| 2229 struct loop *loop = entry->dest->loop_father; | |
| 2230 edge exit_copy; | |
| 2231 edge redirected; | |
| 2232 profile_count curr_count; | |
| 2233 | |
| 2234 if (!can_copy_bbs_p (region, n_region)) | |
| 2235 return false; | |
| 2236 | |
| 131 | 2237 if (dump_file && (dump_flags & TDF_DETAILS)) |
| 2238 { | |
| 2239 fprintf (dump_file, "\nabout to thread: "); | |
| 2240 debug_path (dump_file, current_path_no); | |
| 2241 } | |
| 2242 | |
| 111 | 2243 /* Some sanity checking. Note that we do not check for all possible |
| 2244 missuses of the functions. I.e. if you ask to copy something weird, | |
| 2245 it will work, but the state of structures probably will not be | |
| 2246 correct. */ | |
| 2247 for (i = 0; i < n_region; i++) | |
| 2248 { | |
| 2249 /* We do not handle subloops, i.e. all the blocks must belong to the | |
| 2250 same loop. */ | |
| 2251 if (region[i]->loop_father != loop) | |
| 2252 return false; | |
| 2253 } | |
| 2254 | |
| 2255 initialize_original_copy_tables (); | |
| 2256 | |
| 2257 set_loop_copy (loop, loop); | |
| 2258 | |
| 2259 basic_block *region_copy = XNEWVEC (basic_block, n_region); | |
| 2260 copy_bbs (region, n_region, region_copy, &exit, 1, &exit_copy, loop, | |
| 2261 split_edge_bb_loc (entry), false); | |
| 2262 | |
| 2263 /* Fix up: copy_bbs redirects all edges pointing to copied blocks. The | |
| 2264 following code ensures that all the edges exiting the jump-thread path are | |
| 2265 redirected back to the original code: these edges are exceptions | |
| 2266 invalidating the property that is propagated by executing all the blocks of | |
| 2267 the jump-thread path in order. */ | |
| 2268 | |
| 2269 curr_count = entry->count (); | |
| 2270 | |
| 2271 for (i = 0; i < n_region; i++) | |
| 2272 { | |
| 2273 edge e; | |
| 2274 edge_iterator ei; | |
| 2275 basic_block bb = region_copy[i]; | |
| 2276 | |
| 2277 /* Watch inconsistent profile. */ | |
| 2278 if (curr_count > region[i]->count) | |
| 2279 curr_count = region[i]->count; | |
| 2280 /* Scale current BB. */ | |
| 131 | 2281 if (region[i]->count.nonzero_p () && curr_count.initialized_p ()) |
| 111 | 2282 { |
| 2283 /* In the middle of the path we only scale the frequencies. | |
| 2284 In last BB we need to update probabilities of outgoing edges | |
| 2285 because we know which one is taken at the threaded path. */ | |
| 2286 if (i + 1 != n_region) | |
| 2287 scale_bbs_frequencies_profile_count (region + i, 1, | |
| 2288 region[i]->count - curr_count, | |
| 2289 region[i]->count); | |
| 2290 else | |
| 2291 update_bb_profile_for_threading (region[i], | |
| 131 | 2292 curr_count, |
| 111 | 2293 exit); |
| 2294 scale_bbs_frequencies_profile_count (region_copy + i, 1, curr_count, | |
| 2295 region_copy[i]->count); | |
| 2296 } | |
| 2297 | |
| 2298 if (single_succ_p (bb)) | |
| 2299 { | |
| 2300 /* Make sure the successor is the next node in the path. */ | |
| 2301 gcc_assert (i + 1 == n_region | |
| 2302 || region_copy[i + 1] == single_succ_edge (bb)->dest); | |
| 2303 if (i + 1 != n_region) | |
| 2304 { | |
| 2305 curr_count = single_succ_edge (bb)->count (); | |
| 2306 } | |
| 2307 continue; | |
| 2308 } | |
| 2309 | |
| 2310 /* Special case the last block on the path: make sure that it does not | |
| 2311 jump back on the copied path, including back to itself. */ | |
| 2312 if (i + 1 == n_region) | |
| 2313 { | |
| 2314 FOR_EACH_EDGE (e, ei, bb->succs) | |
| 2315 if (bb_in_bbs (e->dest, region_copy, n_region)) | |
| 2316 { | |
| 2317 basic_block orig = get_bb_original (e->dest); | |
| 2318 if (orig) | |
| 2319 redirect_edge_and_branch_force (e, orig); | |
| 2320 } | |
| 2321 continue; | |
| 2322 } | |
| 2323 | |
| 2324 /* Redirect all other edges jumping to non-adjacent blocks back to the | |
| 2325 original code. */ | |
| 2326 FOR_EACH_EDGE (e, ei, bb->succs) | |
| 2327 if (region_copy[i + 1] != e->dest) | |
| 2328 { | |
| 2329 basic_block orig = get_bb_original (e->dest); | |
| 2330 if (orig) | |
| 2331 redirect_edge_and_branch_force (e, orig); | |
| 2332 } | |
| 2333 else | |
| 2334 { | |
| 2335 curr_count = e->count (); | |
| 2336 } | |
| 2337 } | |
| 2338 | |
| 2339 | |
| 2340 if (flag_checking) | |
| 2341 verify_jump_thread (region_copy, n_region); | |
| 2342 | |
| 2343 /* Remove the last branch in the jump thread path. */ | |
| 2344 remove_ctrl_stmt_and_useless_edges (region_copy[n_region - 1], exit->dest); | |
| 2345 | |
| 2346 /* And fixup the flags on the single remaining edge. */ | |
| 2347 edge fix_e = find_edge (region_copy[n_region - 1], exit->dest); | |
| 2348 fix_e->flags &= ~(EDGE_TRUE_VALUE | EDGE_FALSE_VALUE | EDGE_ABNORMAL); | |
| 2349 fix_e->flags |= EDGE_FALLTHRU; | |
| 2350 | |
| 2351 edge e = make_edge (region_copy[n_region - 1], exit->dest, EDGE_FALLTHRU); | |
| 2352 | |
| 2353 if (e) | |
| 2354 { | |
| 2355 rescan_loop_exit (e, true, false); | |
| 2356 e->probability = profile_probability::always (); | |
| 2357 } | |
| 2358 | |
| 2359 /* Redirect the entry and add the phi node arguments. */ | |
| 2360 if (entry->dest == loop->header) | |
| 2361 mark_loop_for_removal (loop); | |
| 2362 redirected = redirect_edge_and_branch (entry, get_bb_copy (entry->dest)); | |
| 2363 gcc_assert (redirected != NULL); | |
| 2364 flush_pending_stmts (entry); | |
| 2365 | |
| 2366 /* Add the other PHI node arguments. */ | |
| 2367 add_phi_args_after_copy (region_copy, n_region, NULL); | |
| 2368 | |
| 2369 free (region_copy); | |
| 2370 | |
| 131 | 2371 adjust_paths_after_duplication (current_path_no); |
| 2372 | |
| 111 | 2373 free_original_copy_tables (); |
| 2374 return true; | |
| 2375 } | |
| 2376 | |
| 2377 /* Return true when PATH is a valid jump-thread path. */ | |
| 2378 | |
| 2379 static bool | |
| 2380 valid_jump_thread_path (vec<jump_thread_edge *> *path) | |
| 2381 { | |
| 2382 unsigned len = path->length (); | |
| 2383 | |
| 2384 /* Check that the path is connected. */ | |
| 2385 for (unsigned int j = 0; j < len - 1; j++) | |
| 2386 { | |
| 2387 edge e = (*path)[j]->e; | |
| 2388 if (e->dest != (*path)[j+1]->e->src) | |
| 2389 return false; | |
| 2390 } | |
| 2391 return true; | |
| 2392 } | |
| 2393 | |
| 2394 /* Remove any queued jump threads that include edge E. | |
| 2395 | |
| 2396 We don't actually remove them here, just record the edges into ax | |
| 2397 hash table. That way we can do the search once per iteration of | |
| 2398 DOM/VRP rather than for every case where DOM optimizes away a COND_EXPR. */ | |
| 2399 | |
| 2400 void | |
| 2401 remove_jump_threads_including (edge_def *e) | |
| 2402 { | |
| 2403 if (!paths.exists ()) | |
| 2404 return; | |
| 2405 | |
| 2406 if (!removed_edges) | |
| 2407 removed_edges = new hash_table<struct removed_edges> (17); | |
| 2408 | |
| 2409 edge *slot = removed_edges->find_slot (e, INSERT); | |
| 2410 *slot = e; | |
| 2411 } | |
| 0 | 2412 |
| 2413 /* Walk through all blocks and thread incoming edges to the appropriate | |
| 2414 outgoing edge for each edge pair recorded in THREADED_EDGES. | |
| 2415 | |
| 2416 It is the caller's responsibility to fix the dominance information | |
| 2417 and rewrite duplicated SSA_NAMEs back into SSA form. | |
| 2418 | |
| 2419 If MAY_PEEL_LOOP_HEADERS is false, we avoid threading edges through | |
| 2420 loop headers if it does not simplify the loop. | |
| 2421 | |
| 2422 Returns true if one or more edges were threaded, false otherwise. */ | |
| 2423 | |
| 2424 bool | |
| 2425 thread_through_all_blocks (bool may_peel_loop_headers) | |
| 2426 { | |
| 2427 bool retval = false; | |
| 2428 unsigned int i; | |
| 2429 struct loop *loop; | |
| 111 | 2430 auto_bitmap threaded_blocks; |
| 131 | 2431 hash_set<edge> visited_starting_edges; |
| 111 | 2432 |
| 2433 if (!paths.exists ()) | |
| 2434 { | |
| 2435 retval = false; | |
| 2436 goto out; | |
| 2437 } | |
| 2438 | |
| 0 | 2439 memset (&thread_stats, 0, sizeof (thread_stats)); |
| 2440 | |
| 111 | 2441 /* Remove any paths that referenced removed edges. */ |
| 2442 if (removed_edges) | |
| 2443 for (i = 0; i < paths.length (); ) | |
| 2444 { | |
| 2445 unsigned int j; | |
| 2446 vec<jump_thread_edge *> *path = paths[i]; | |
| 2447 | |
| 2448 for (j = 0; j < path->length (); j++) | |
| 2449 { | |
| 2450 edge e = (*path)[j]->e; | |
| 2451 if (removed_edges->find_slot (e, NO_INSERT)) | |
| 2452 break; | |
| 2453 } | |
| 2454 | |
| 2455 if (j != path->length ()) | |
| 2456 { | |
| 2457 delete_jump_thread_path (path); | |
| 2458 paths.unordered_remove (i); | |
| 2459 continue; | |
| 2460 } | |
| 2461 i++; | |
| 2462 } | |
| 2463 | |
| 2464 /* Jump-thread all FSM threads before other jump-threads. */ | |
| 2465 for (i = 0; i < paths.length ();) | |
| 2466 { | |
| 2467 vec<jump_thread_edge *> *path = paths[i]; | |
| 2468 edge entry = (*path)[0]->e; | |
| 2469 | |
| 2470 /* Only code-generate FSM jump-threads in this loop. */ | |
| 2471 if ((*path)[0]->type != EDGE_FSM_THREAD) | |
| 2472 { | |
| 2473 i++; | |
| 2474 continue; | |
| 2475 } | |
| 2476 | |
| 131 | 2477 /* Do not jump-thread twice from the same starting edge. |
| 2478 | |
| 2479 Previously we only checked that we weren't threading twice | |
| 2480 from the same BB, but that was too restrictive. Imagine a | |
| 2481 path that starts from GIMPLE_COND(x_123 == 0,...), where both | |
| 2482 edges out of this conditional yield paths that can be | |
| 2483 threaded (for example, both lead to an x_123==0 or x_123!=0 | |
| 2484 conditional further down the line. */ | |
| 2485 if (visited_starting_edges.contains (entry) | |
| 2486 /* We may not want to realize this jump thread path for | |
| 2487 various reasons. So check it first. */ | |
| 111 | 2488 || !valid_jump_thread_path (path)) |
| 2489 { | |
| 2490 /* Remove invalid FSM jump-thread paths. */ | |
| 2491 delete_jump_thread_path (path); | |
| 2492 paths.unordered_remove (i); | |
| 2493 continue; | |
| 2494 } | |
| 2495 | |
| 2496 unsigned len = path->length (); | |
| 2497 edge exit = (*path)[len - 1]->e; | |
| 2498 basic_block *region = XNEWVEC (basic_block, len - 1); | |
| 2499 | |
| 2500 for (unsigned int j = 0; j < len - 1; j++) | |
| 2501 region[j] = (*path)[j]->e->dest; | |
| 2502 | |
| 131 | 2503 if (duplicate_thread_path (entry, exit, region, len - 1, i)) |
| 111 | 2504 { |
| 2505 /* We do not update dominance info. */ | |
| 2506 free_dominance_info (CDI_DOMINATORS); | |
| 131 | 2507 visited_starting_edges.add (entry); |
| 111 | 2508 retval = true; |
| 2509 thread_stats.num_threaded_edges++; | |
| 2510 } | |
| 2511 | |
| 2512 delete_jump_thread_path (path); | |
| 2513 paths.unordered_remove (i); | |
| 2514 free (region); | |
| 2515 } | |
| 2516 | |
| 2517 /* Remove from PATHS all the jump-threads starting with an edge already | |
| 2518 jump-threaded. */ | |
| 2519 for (i = 0; i < paths.length ();) | |
| 2520 { | |
| 2521 vec<jump_thread_edge *> *path = paths[i]; | |
| 2522 edge entry = (*path)[0]->e; | |
| 2523 | |
| 2524 /* Do not jump-thread twice from the same block. */ | |
| 131 | 2525 if (visited_starting_edges.contains (entry)) |
| 111 | 2526 { |
| 2527 delete_jump_thread_path (path); | |
| 2528 paths.unordered_remove (i); | |
| 2529 } | |
| 2530 else | |
| 2531 i++; | |
| 2532 } | |
| 2533 | |
| 0 | 2534 mark_threaded_blocks (threaded_blocks); |
| 2535 | |
| 2536 initialize_original_copy_tables (); | |
| 2537 | |
| 131 | 2538 /* The order in which we process jump threads can be important. |
| 2539 | |
| 2540 Consider if we have two jump threading paths A and B. If the | |
| 2541 target edge of A is the starting edge of B and we thread path A | |
| 2542 first, then we create an additional incoming edge into B->dest that | |
| 2543 we can not discover as a jump threading path on this iteration. | |
| 2544 | |
| 2545 If we instead thread B first, then the edge into B->dest will have | |
| 2546 already been redirected before we process path A and path A will | |
| 2547 natually, with no further work, target the redirected path for B. | |
| 2548 | |
| 2549 An post-order is sufficient here. Compute the ordering first, then | |
| 2550 process the blocks. */ | |
| 2551 if (!bitmap_empty_p (threaded_blocks)) | |
| 0 | 2552 { |
| 131 | 2553 int *postorder = XNEWVEC (int, n_basic_blocks_for_fn (cfun)); |
| 2554 unsigned int postorder_num = post_order_compute (postorder, false, false); | |
| 2555 for (unsigned int i = 0; i < postorder_num; i++) | |
| 2556 { | |
| 2557 unsigned int indx = postorder[i]; | |
| 2558 if (bitmap_bit_p (threaded_blocks, indx)) | |
| 2559 { | |
| 2560 basic_block bb = BASIC_BLOCK_FOR_FN (cfun, indx); | |
| 2561 retval |= thread_block (bb, true); | |
| 2562 } | |
| 2563 } | |
| 2564 free (postorder); | |
| 0 | 2565 } |
| 2566 | |
| 2567 /* Then perform the threading through loop headers. We start with the | |
| 2568 innermost loop, so that the changes in cfg we perform won't affect | |
| 2569 further threading. */ | |
| 111 | 2570 FOR_EACH_LOOP (loop, LI_FROM_INNERMOST) |
| 0 | 2571 { |
| 2572 if (!loop->header | |
| 2573 || !bitmap_bit_p (threaded_blocks, loop->header->index)) | |
| 2574 continue; | |
| 2575 | |
| 2576 retval |= thread_through_loop_header (loop, may_peel_loop_headers); | |
| 2577 } | |
| 2578 | |
| 111 | 2579 /* All jump threading paths should have been resolved at this |
| 2580 point. Verify that is the case. */ | |
| 2581 basic_block bb; | |
| 2582 FOR_EACH_BB_FN (bb, cfun) | |
| 2583 { | |
| 2584 edge_iterator ei; | |
| 2585 edge e; | |
| 2586 FOR_EACH_EDGE (e, ei, bb->preds) | |
| 2587 gcc_assert (e->aux == NULL); | |
| 2588 } | |
| 2589 | |
| 0 | 2590 statistics_counter_event (cfun, "Jumps threaded", |
| 2591 thread_stats.num_threaded_edges); | |
| 2592 | |
| 2593 free_original_copy_tables (); | |
| 2594 | |
| 111 | 2595 paths.release (); |
| 0 | 2596 |
| 2597 if (retval) | |
| 2598 loops_state_set (LOOPS_NEED_FIXUP); | |
| 2599 | |
| 111 | 2600 out: |
| 2601 delete removed_edges; | |
| 2602 removed_edges = NULL; | |
| 0 | 2603 return retval; |
| 2604 } | |
| 2605 | |
| 111 | 2606 /* Delete the jump threading path PATH. We have to explicitly delete |
| 2607 each entry in the vector, then the container. */ | |
| 2608 | |
| 2609 void | |
| 2610 delete_jump_thread_path (vec<jump_thread_edge *> *path) | |
| 2611 { | |
| 2612 for (unsigned int i = 0; i < path->length (); i++) | |
| 2613 delete (*path)[i]; | |
| 2614 path->release(); | |
| 2615 delete path; | |
| 2616 } | |
| 2617 | |
| 0 | 2618 /* Register a jump threading opportunity. We queue up all the jump |
| 2619 threading opportunities discovered by a pass and update the CFG | |
| 2620 and SSA form all at once. | |
| 2621 | |
| 2622 E is the edge we can thread, E2 is the new target edge, i.e., we | |
| 2623 are effectively recording that E->dest can be changed to E2->dest | |
| 2624 after fixing the SSA graph. */ | |
| 2625 | |
| 2626 void | |
| 111 | 2627 register_jump_thread (vec<jump_thread_edge *> *path) |
| 0 | 2628 { |
| 111 | 2629 if (!dbg_cnt (registered_jump_thread)) |
| 2630 { | |
| 2631 delete_jump_thread_path (path); | |
| 2632 return; | |
| 2633 } | |
| 2634 | |
| 2635 /* First make sure there are no NULL outgoing edges on the jump threading | |
| 2636 path. That can happen for jumping to a constant address. */ | |
| 2637 for (unsigned int i = 0; i < path->length (); i++) | |
| 2638 { | |
| 2639 if ((*path)[i]->e == NULL) | |
| 2640 { | |
| 2641 if (dump_file && (dump_flags & TDF_DETAILS)) | |
| 2642 { | |
| 2643 fprintf (dump_file, | |
| 2644 "Found NULL edge in jump threading path. Cancelling jump thread:\n"); | |
| 2645 dump_jump_thread_path (dump_file, *path, false); | |
| 2646 } | |
| 2647 | |
| 2648 delete_jump_thread_path (path); | |
| 2649 return; | |
| 2650 } | |
| 2651 | |
| 2652 /* Only the FSM threader is allowed to thread across | |
| 2653 backedges in the CFG. */ | |
| 2654 if (flag_checking | |
| 2655 && (*path)[0]->type != EDGE_FSM_THREAD) | |
| 2656 gcc_assert (((*path)[i]->e->flags & EDGE_DFS_BACK) == 0); | |
| 2657 } | |
| 2658 | |
| 2659 if (dump_file && (dump_flags & TDF_DETAILS)) | |
| 2660 dump_jump_thread_path (dump_file, *path, true); | |
| 2661 | |
| 2662 if (!paths.exists ()) | |
| 2663 paths.create (5); | |
| 2664 | |
| 2665 paths.safe_push (path); | |
| 0 | 2666 } |
| 131 | 2667 |
| 2668 /* Return how many uses of T there are within BB, as long as there | |
| 2669 aren't any uses outside BB. If there are any uses outside BB, | |
| 2670 return -1 if there's at most one use within BB, or -2 if there is | |
| 2671 more than one use within BB. */ | |
| 2672 | |
| 2673 static int | |
| 2674 uses_in_bb (tree t, basic_block bb) | |
| 2675 { | |
| 2676 int uses = 0; | |
| 2677 bool outside_bb = false; | |
| 2678 | |
| 2679 imm_use_iterator iter; | |
| 2680 use_operand_p use_p; | |
| 2681 FOR_EACH_IMM_USE_FAST (use_p, iter, t) | |
| 2682 { | |
| 2683 if (is_gimple_debug (USE_STMT (use_p))) | |
| 2684 continue; | |
| 2685 | |
| 2686 if (gimple_bb (USE_STMT (use_p)) != bb) | |
| 2687 outside_bb = true; | |
| 2688 else | |
| 2689 uses++; | |
| 2690 | |
| 2691 if (outside_bb && uses > 1) | |
| 2692 return -2; | |
| 2693 } | |
| 2694 | |
| 2695 if (outside_bb) | |
| 2696 return -1; | |
| 2697 | |
| 2698 return uses; | |
| 2699 } | |
| 2700 | |
| 2701 /* Starting from the final control flow stmt in BB, assuming it will | |
| 2702 be removed, follow uses in to-be-removed stmts back to their defs | |
| 2703 and count how many defs are to become dead and be removed as | |
| 2704 well. */ | |
| 2705 | |
| 2706 unsigned int | |
| 2707 estimate_threading_killed_stmts (basic_block bb) | |
| 2708 { | |
| 2709 int killed_stmts = 0; | |
| 2710 hash_map<tree, int> ssa_remaining_uses; | |
| 2711 auto_vec<gimple *, 4> dead_worklist; | |
| 2712 | |
| 2713 /* If the block has only two predecessors, threading will turn phi | |
| 2714 dsts into either src, so count them as dead stmts. */ | |
| 2715 bool drop_all_phis = EDGE_COUNT (bb->preds) == 2; | |
| 2716 | |
| 2717 if (drop_all_phis) | |
| 2718 for (gphi_iterator gsi = gsi_start_phis (bb); | |
| 2719 !gsi_end_p (gsi); gsi_next (&gsi)) | |
| 2720 { | |
| 2721 gphi *phi = gsi.phi (); | |
| 2722 tree dst = gimple_phi_result (phi); | |
| 2723 | |
| 2724 /* We don't count virtual PHIs as stmts in | |
| 2725 record_temporary_equivalences_from_phis. */ | |
| 2726 if (virtual_operand_p (dst)) | |
| 2727 continue; | |
| 2728 | |
| 2729 killed_stmts++; | |
| 2730 } | |
| 2731 | |
| 2732 if (gsi_end_p (gsi_last_bb (bb))) | |
| 2733 return killed_stmts; | |
| 2734 | |
| 2735 gimple *stmt = gsi_stmt (gsi_last_bb (bb)); | |
| 2736 if (gimple_code (stmt) != GIMPLE_COND | |
| 2737 && gimple_code (stmt) != GIMPLE_GOTO | |
| 2738 && gimple_code (stmt) != GIMPLE_SWITCH) | |
| 2739 return killed_stmts; | |
| 2740 | |
| 2741 /* The control statement is always dead. */ | |
| 2742 killed_stmts++; | |
| 2743 dead_worklist.quick_push (stmt); | |
| 2744 while (!dead_worklist.is_empty ()) | |
| 2745 { | |
| 2746 stmt = dead_worklist.pop (); | |
| 2747 | |
| 2748 ssa_op_iter iter; | |
| 2749 use_operand_p use_p; | |
| 2750 FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, SSA_OP_USE) | |
| 2751 { | |
| 2752 tree t = USE_FROM_PTR (use_p); | |
| 2753 gimple *def = SSA_NAME_DEF_STMT (t); | |
| 2754 | |
| 2755 if (gimple_bb (def) == bb | |
| 2756 && (gimple_code (def) != GIMPLE_PHI | |
| 2757 || !drop_all_phis) | |
| 2758 && !gimple_has_side_effects (def)) | |
| 2759 { | |
| 2760 int *usesp = ssa_remaining_uses.get (t); | |
| 2761 int uses; | |
| 2762 | |
| 2763 if (usesp) | |
| 2764 uses = *usesp; | |
| 2765 else | |
| 2766 uses = uses_in_bb (t, bb); | |
| 2767 | |
| 2768 gcc_assert (uses); | |
| 2769 | |
| 2770 /* Don't bother recording the expected use count if we | |
| 2771 won't find any further uses within BB. */ | |
| 2772 if (!usesp && (uses < -1 || uses > 1)) | |
| 2773 { | |
| 2774 usesp = &ssa_remaining_uses.get_or_insert (t); | |
| 2775 *usesp = uses; | |
| 2776 } | |
| 2777 | |
| 2778 if (uses < 0) | |
| 2779 continue; | |
| 2780 | |
| 2781 --uses; | |
| 2782 if (usesp) | |
| 2783 *usesp = uses; | |
| 2784 | |
| 2785 if (!uses) | |
| 2786 { | |
| 2787 killed_stmts++; | |
| 2788 if (usesp) | |
| 2789 ssa_remaining_uses.remove (t); | |
| 2790 if (gimple_code (def) != GIMPLE_PHI) | |
| 2791 dead_worklist.safe_push (def); | |
| 2792 } | |
| 2793 } | |
| 2794 } | |
| 2795 } | |
| 2796 | |
| 2797 if (dump_file) | |
| 2798 fprintf (dump_file, "threading bb %i kills %i stmts\n", | |
| 2799 bb->index, killed_stmts); | |
| 2800 | |
| 2801 return killed_stmts; | |
| 2802 } |