1/* Loop manipulation code for GNU compiler. 2 Copyright (C) 2002-2015 Free Software Foundation, Inc. 3 4This file is part of GCC. 5 6GCC is free software; you can redistribute it and/or modify it under 7the terms of the GNU General Public License as published by the Free 8Software Foundation; either version 3, or (at your option) any later 9version. 10 11GCC is distributed in the hope that it will be useful, but WITHOUT ANY 12WARRANTY; without even the implied warranty of MERCHANTABILITY or 13FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14for more details. 15 16You should have received a copy of the GNU General Public License 17along 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" 23#include "tm.h" 24#include "rtl.h" 25#include "predict.h" 26#include "vec.h" 27#include "hashtab.h" 28#include "hash-set.h" 29#include "symtab.h" 30#include "inchash.h" 31#include "machmode.h" 32#include "hard-reg-set.h" 33#include "input.h" 34#include "function.h" 35#include "dominance.h" 36#include "cfg.h" 37#include "cfganal.h" 38#include "basic-block.h" 39#include "cfgloop.h" 40#include "tree.h" 41#include "fold-const.h" 42#include "tree-ssa-alias.h" 43#include "internal-fn.h" 44#include "gimple-expr.h" 45#include "is-a.h" 46#include "gimple.h" 47#include "gimple-iterator.h" 48#include "gimplify-me.h" 49#include "tree-ssa-loop-manip.h" 50#include "dumpfile.h" 51 52static void copy_loops_to (struct loop **, int, 53 struct loop *); 54static void loop_redirect_edge (edge, basic_block); 55static void remove_bbs (basic_block *, int); 56static bool rpe_enum_p (const_basic_block, const void *); 57static int find_path (edge, basic_block **); 58static void fix_loop_placements (struct loop *, bool *); 59static bool fix_bb_placement (basic_block); 60static void fix_bb_placements (basic_block, bool *, bitmap); 61 62/* Checks whether basic block BB is dominated by DATA. */ 63static bool 64rpe_enum_p (const_basic_block bb, const void *data) 65{ 66 return dominated_by_p (CDI_DOMINATORS, bb, (const_basic_block) data); 67} 68 69/* Remove basic blocks BBS. NBBS is the number of the basic blocks. */ 70 71static void 72remove_bbs (basic_block *bbs, int nbbs) 73{ 74 int i; 75 76 for (i = 0; i < nbbs; i++) 77 delete_basic_block (bbs[i]); 78} 79 80/* Find path -- i.e. the basic blocks dominated by edge E and put them 81 into array BBS, that will be allocated large enough to contain them. 82 E->dest must have exactly one predecessor for this to work (it is 83 easy to achieve and we do not put it here because we do not want to 84 alter anything by this function). The number of basic blocks in the 85 path is returned. */ 86static int 87find_path (edge e, basic_block **bbs) 88{ 89 gcc_assert (EDGE_COUNT (e->dest->preds) <= 1); 90 91 /* Find bbs in the path. */ 92 *bbs = XNEWVEC (basic_block, n_basic_blocks_for_fn (cfun)); 93 return dfs_enumerate_from (e->dest, 0, rpe_enum_p, *bbs, 94 n_basic_blocks_for_fn (cfun), e->dest); 95} 96 97/* Fix placement of basic block BB inside loop hierarchy -- 98 Let L be a loop to that BB belongs. Then every successor of BB must either 99 1) belong to some superloop of loop L, or 100 2) be a header of loop K such that K->outer is superloop of L 101 Returns true if we had to move BB into other loop to enforce this condition, 102 false if the placement of BB was already correct (provided that placements 103 of its successors are correct). */ 104static bool 105fix_bb_placement (basic_block bb) 106{ 107 edge e; 108 edge_iterator ei; 109 struct loop *loop = current_loops->tree_root, *act; 110 111 FOR_EACH_EDGE (e, ei, bb->succs) 112 { 113 if (e->dest == EXIT_BLOCK_PTR_FOR_FN (cfun)) 114 continue; 115 116 act = e->dest->loop_father; 117 if (act->header == e->dest) 118 act = loop_outer (act); 119 120 if (flow_loop_nested_p (loop, act)) 121 loop = act; 122 } 123 124 if (loop == bb->loop_father) 125 return false; 126 127 remove_bb_from_loops (bb); 128 add_bb_to_loop (bb, loop); 129 130 return true; 131} 132 133/* Fix placement of LOOP inside loop tree, i.e. find the innermost superloop 134 of LOOP to that leads at least one exit edge of LOOP, and set it 135 as the immediate superloop of LOOP. Return true if the immediate superloop 136 of LOOP changed. 137 138 IRRED_INVALIDATED is set to true if a change in the loop structures might 139 invalidate the information about irreducible regions. */ 140 141static bool 142fix_loop_placement (struct loop *loop, bool *irred_invalidated) 143{ 144 unsigned i; 145 edge e; 146 vec<edge> exits = get_loop_exit_edges (loop); 147 struct loop *father = current_loops->tree_root, *act; 148 bool ret = false; 149 150 FOR_EACH_VEC_ELT (exits, i, e) 151 { 152 act = find_common_loop (loop, e->dest->loop_father); 153 if (flow_loop_nested_p (father, act)) 154 father = act; 155 } 156 157 if (father != loop_outer (loop)) 158 { 159 for (act = loop_outer (loop); act != father; act = loop_outer (act)) 160 act->num_nodes -= loop->num_nodes; 161 flow_loop_tree_node_remove (loop); 162 flow_loop_tree_node_add (father, loop); 163 164 /* The exit edges of LOOP no longer exits its original immediate 165 superloops; remove them from the appropriate exit lists. */ 166 FOR_EACH_VEC_ELT (exits, i, e) 167 { 168 /* We may need to recompute irreducible loops. */ 169 if (e->flags & EDGE_IRREDUCIBLE_LOOP) 170 *irred_invalidated = true; 171 rescan_loop_exit (e, false, false); 172 } 173 174 ret = true; 175 } 176 177 exits.release (); 178 return ret; 179} 180 181/* Fix placements of basic blocks inside loop hierarchy stored in loops; i.e. 182 enforce condition condition stated in description of fix_bb_placement. We 183 start from basic block FROM that had some of its successors removed, so that 184 his placement no longer has to be correct, and iteratively fix placement of 185 its predecessors that may change if placement of FROM changed. Also fix 186 placement of subloops of FROM->loop_father, that might also be altered due 187 to this change; the condition for them is similar, except that instead of 188 successors we consider edges coming out of the loops. 189 190 If the changes may invalidate the information about irreducible regions, 191 IRRED_INVALIDATED is set to true. 192 193 If LOOP_CLOSED_SSA_INVLIDATED is non-zero then all basic blocks with 194 changed loop_father are collected there. */ 195 196static void 197fix_bb_placements (basic_block from, 198 bool *irred_invalidated, 199 bitmap loop_closed_ssa_invalidated) 200{ 201 sbitmap in_queue; 202 basic_block *queue, *qtop, *qbeg, *qend; 203 struct loop *base_loop, *target_loop; 204 edge e; 205 206 /* We pass through blocks back-reachable from FROM, testing whether some 207 of their successors moved to outer loop. It may be necessary to 208 iterate several times, but it is finite, as we stop unless we move 209 the basic block up the loop structure. The whole story is a bit 210 more complicated due to presence of subloops, those are moved using 211 fix_loop_placement. */ 212 213 base_loop = from->loop_father; 214 /* If we are already in the outermost loop, the basic blocks cannot be moved 215 outside of it. If FROM is the header of the base loop, it cannot be moved 216 outside of it, either. In both cases, we can end now. */ 217 if (base_loop == current_loops->tree_root 218 || from == base_loop->header) 219 return; 220 221 in_queue = sbitmap_alloc (last_basic_block_for_fn (cfun)); 222 bitmap_clear (in_queue); 223 bitmap_set_bit (in_queue, from->index); 224 /* Prevent us from going out of the base_loop. */ 225 bitmap_set_bit (in_queue, base_loop->header->index); 226 227 queue = XNEWVEC (basic_block, base_loop->num_nodes + 1); 228 qtop = queue + base_loop->num_nodes + 1; 229 qbeg = queue; 230 qend = queue + 1; 231 *qbeg = from; 232 233 while (qbeg != qend) 234 { 235 edge_iterator ei; 236 from = *qbeg; 237 qbeg++; 238 if (qbeg == qtop) 239 qbeg = queue; 240 bitmap_clear_bit (in_queue, from->index); 241 242 if (from->loop_father->header == from) 243 { 244 /* Subloop header, maybe move the loop upward. */ 245 if (!fix_loop_placement (from->loop_father, irred_invalidated)) 246 continue; 247 target_loop = loop_outer (from->loop_father); 248 if (loop_closed_ssa_invalidated) 249 { 250 basic_block *bbs = get_loop_body (from->loop_father); 251 for (unsigned i = 0; i < from->loop_father->num_nodes; ++i) 252 bitmap_set_bit (loop_closed_ssa_invalidated, bbs[i]->index); 253 free (bbs); 254 } 255 } 256 else 257 { 258 /* Ordinary basic block. */ 259 if (!fix_bb_placement (from)) 260 continue; 261 target_loop = from->loop_father; 262 if (loop_closed_ssa_invalidated) 263 bitmap_set_bit (loop_closed_ssa_invalidated, from->index); 264 } 265 266 FOR_EACH_EDGE (e, ei, from->succs) 267 { 268 if (e->flags & EDGE_IRREDUCIBLE_LOOP) 269 *irred_invalidated = true; 270 } 271 272 /* Something has changed, insert predecessors into queue. */ 273 FOR_EACH_EDGE (e, ei, from->preds) 274 { 275 basic_block pred = e->src; 276 struct loop *nca; 277 278 if (e->flags & EDGE_IRREDUCIBLE_LOOP) 279 *irred_invalidated = true; 280 281 if (bitmap_bit_p (in_queue, pred->index)) 282 continue; 283 284 /* If it is subloop, then it either was not moved, or 285 the path up the loop tree from base_loop do not contain 286 it. */ 287 nca = find_common_loop (pred->loop_father, base_loop); 288 if (pred->loop_father != base_loop 289 && (nca == base_loop 290 || nca != pred->loop_father)) 291 pred = pred->loop_father->header; 292 else if (!flow_loop_nested_p (target_loop, pred->loop_father)) 293 { 294 /* If PRED is already higher in the loop hierarchy than the 295 TARGET_LOOP to that we moved FROM, the change of the position 296 of FROM does not affect the position of PRED, so there is no 297 point in processing it. */ 298 continue; 299 } 300 301 if (bitmap_bit_p (in_queue, pred->index)) 302 continue; 303 304 /* Schedule the basic block. */ 305 *qend = pred; 306 qend++; 307 if (qend == qtop) 308 qend = queue; 309 bitmap_set_bit (in_queue, pred->index); 310 } 311 } 312 free (in_queue); 313 free (queue); 314} 315 316/* Removes path beginning at edge E, i.e. remove basic blocks dominated by E 317 and update loop structures and dominators. Return true if we were able 318 to remove the path, false otherwise (and nothing is affected then). */ 319bool 320remove_path (edge e) 321{ 322 edge ae; 323 basic_block *rem_bbs, *bord_bbs, from, bb; 324 vec<basic_block> dom_bbs; 325 int i, nrem, n_bord_bbs; 326 sbitmap seen; 327 bool irred_invalidated = false; 328 edge_iterator ei; 329 struct loop *l, *f; 330 331 if (!can_remove_branch_p (e)) 332 return false; 333 334 /* Keep track of whether we need to update information about irreducible 335 regions. This is the case if the removed area is a part of the 336 irreducible region, or if the set of basic blocks that belong to a loop 337 that is inside an irreducible region is changed, or if such a loop is 338 removed. */ 339 if (e->flags & EDGE_IRREDUCIBLE_LOOP) 340 irred_invalidated = true; 341 342 /* We need to check whether basic blocks are dominated by the edge 343 e, but we only have basic block dominators. This is easy to 344 fix -- when e->dest has exactly one predecessor, this corresponds 345 to blocks dominated by e->dest, if not, split the edge. */ 346 if (!single_pred_p (e->dest)) 347 e = single_pred_edge (split_edge (e)); 348 349 /* It may happen that by removing path we remove one or more loops 350 we belong to. In this case first unloop the loops, then proceed 351 normally. We may assume that e->dest is not a header of any loop, 352 as it now has exactly one predecessor. */ 353 for (l = e->src->loop_father; loop_outer (l); l = f) 354 { 355 f = loop_outer (l); 356 if (dominated_by_p (CDI_DOMINATORS, l->latch, e->dest)) 357 unloop (l, &irred_invalidated, NULL); 358 } 359 360 /* Identify the path. */ 361 nrem = find_path (e, &rem_bbs); 362 363 n_bord_bbs = 0; 364 bord_bbs = XNEWVEC (basic_block, n_basic_blocks_for_fn (cfun)); 365 seen = sbitmap_alloc (last_basic_block_for_fn (cfun)); 366 bitmap_clear (seen); 367 368 /* Find "border" hexes -- i.e. those with predecessor in removed path. */ 369 for (i = 0; i < nrem; i++) 370 bitmap_set_bit (seen, rem_bbs[i]->index); 371 if (!irred_invalidated) 372 FOR_EACH_EDGE (ae, ei, e->src->succs) 373 if (ae != e && ae->dest != EXIT_BLOCK_PTR_FOR_FN (cfun) 374 && !bitmap_bit_p (seen, ae->dest->index) 375 && ae->flags & EDGE_IRREDUCIBLE_LOOP) 376 { 377 irred_invalidated = true; 378 break; 379 } 380 381 for (i = 0; i < nrem; i++) 382 { 383 bb = rem_bbs[i]; 384 FOR_EACH_EDGE (ae, ei, rem_bbs[i]->succs) 385 if (ae->dest != EXIT_BLOCK_PTR_FOR_FN (cfun) 386 && !bitmap_bit_p (seen, ae->dest->index)) 387 { 388 bitmap_set_bit (seen, ae->dest->index); 389 bord_bbs[n_bord_bbs++] = ae->dest; 390 391 if (ae->flags & EDGE_IRREDUCIBLE_LOOP) 392 irred_invalidated = true; 393 } 394 } 395 396 /* Remove the path. */ 397 from = e->src; 398 remove_branch (e); 399 dom_bbs.create (0); 400 401 /* Cancel loops contained in the path. */ 402 for (i = 0; i < nrem; i++) 403 if (rem_bbs[i]->loop_father->header == rem_bbs[i]) 404 cancel_loop_tree (rem_bbs[i]->loop_father); 405 406 remove_bbs (rem_bbs, nrem); 407 free (rem_bbs); 408 409 /* Find blocks whose dominators may be affected. */ 410 bitmap_clear (seen); 411 for (i = 0; i < n_bord_bbs; i++) 412 { 413 basic_block ldom; 414 415 bb = get_immediate_dominator (CDI_DOMINATORS, bord_bbs[i]); 416 if (bitmap_bit_p (seen, bb->index)) 417 continue; 418 bitmap_set_bit (seen, bb->index); 419 420 for (ldom = first_dom_son (CDI_DOMINATORS, bb); 421 ldom; 422 ldom = next_dom_son (CDI_DOMINATORS, ldom)) 423 if (!dominated_by_p (CDI_DOMINATORS, from, ldom)) 424 dom_bbs.safe_push (ldom); 425 } 426 427 free (seen); 428 429 /* Recount dominators. */ 430 iterate_fix_dominators (CDI_DOMINATORS, dom_bbs, true); 431 dom_bbs.release (); 432 free (bord_bbs); 433 434 /* Fix placements of basic blocks inside loops and the placement of 435 loops in the loop tree. */ 436 fix_bb_placements (from, &irred_invalidated, NULL); 437 fix_loop_placements (from->loop_father, &irred_invalidated); 438 439 if (irred_invalidated 440 && loops_state_satisfies_p (LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS)) 441 mark_irreducible_loops (); 442 443 return true; 444} 445 446/* Creates place for a new LOOP in loops structure of FN. */ 447 448void 449place_new_loop (struct function *fn, struct loop *loop) 450{ 451 loop->num = number_of_loops (fn); 452 vec_safe_push (loops_for_fn (fn)->larray, loop); 453} 454 455/* Given LOOP structure with filled header and latch, find the body of the 456 corresponding loop and add it to loops tree. Insert the LOOP as a son of 457 outer. */ 458 459void 460add_loop (struct loop *loop, struct loop *outer) 461{ 462 basic_block *bbs; 463 int i, n; 464 struct loop *subloop; 465 edge e; 466 edge_iterator ei; 467 468 /* Add it to loop structure. */ 469 place_new_loop (cfun, loop); 470 flow_loop_tree_node_add (outer, loop); 471 472 /* Find its nodes. */ 473 bbs = XNEWVEC (basic_block, n_basic_blocks_for_fn (cfun)); 474 n = get_loop_body_with_size (loop, bbs, n_basic_blocks_for_fn (cfun)); 475 476 for (i = 0; i < n; i++) 477 { 478 if (bbs[i]->loop_father == outer) 479 { 480 remove_bb_from_loops (bbs[i]); 481 add_bb_to_loop (bbs[i], loop); 482 continue; 483 } 484 485 loop->num_nodes++; 486 487 /* If we find a direct subloop of OUTER, move it to LOOP. */ 488 subloop = bbs[i]->loop_father; 489 if (loop_outer (subloop) == outer 490 && subloop->header == bbs[i]) 491 { 492 flow_loop_tree_node_remove (subloop); 493 flow_loop_tree_node_add (loop, subloop); 494 } 495 } 496 497 /* Update the information about loop exit edges. */ 498 for (i = 0; i < n; i++) 499 { 500 FOR_EACH_EDGE (e, ei, bbs[i]->succs) 501 { 502 rescan_loop_exit (e, false, false); 503 } 504 } 505 506 free (bbs); 507} 508 509/* Multiply all frequencies in LOOP by NUM/DEN. */ 510 511void 512scale_loop_frequencies (struct loop *loop, int num, int den) 513{ 514 basic_block *bbs; 515 516 bbs = get_loop_body (loop); 517 scale_bbs_frequencies_int (bbs, loop->num_nodes, num, den); 518 free (bbs); 519} 520 521/* Multiply all frequencies in LOOP by SCALE/REG_BR_PROB_BASE. 522 If ITERATION_BOUND is non-zero, scale even further if loop is predicted 523 to iterate too many times. */ 524 525void 526scale_loop_profile (struct loop *loop, int scale, gcov_type iteration_bound) 527{ 528 gcov_type iterations = expected_loop_iterations_unbounded (loop); 529 edge e; 530 edge_iterator ei; 531 532 if (dump_file && (dump_flags & TDF_DETAILS)) 533 fprintf (dump_file, ";; Scaling loop %i with scale %f, " 534 "bounding iterations to %i from guessed %i\n", 535 loop->num, (double)scale / REG_BR_PROB_BASE, 536 (int)iteration_bound, (int)iterations); 537 538 /* See if loop is predicted to iterate too many times. */ 539 if (iteration_bound && iterations > 0 540 && apply_probability (iterations, scale) > iteration_bound) 541 { 542 /* Fixing loop profile for different trip count is not trivial; the exit 543 probabilities has to be updated to match and frequencies propagated down 544 to the loop body. 545 546 We fully update only the simple case of loop with single exit that is 547 either from the latch or BB just before latch and leads from BB with 548 simple conditional jump. This is OK for use in vectorizer. */ 549 e = single_exit (loop); 550 if (e) 551 { 552 edge other_e; 553 int freq_delta; 554 gcov_type count_delta; 555 556 FOR_EACH_EDGE (other_e, ei, e->src->succs) 557 if (!(other_e->flags & (EDGE_ABNORMAL | EDGE_FAKE)) 558 && e != other_e) 559 break; 560 561 /* Probability of exit must be 1/iterations. */ 562 freq_delta = EDGE_FREQUENCY (e); 563 e->probability = REG_BR_PROB_BASE / iteration_bound; 564 other_e->probability = inverse_probability (e->probability); 565 freq_delta -= EDGE_FREQUENCY (e); 566 567 /* Adjust counts accordingly. */ 568 count_delta = e->count; 569 e->count = apply_probability (e->src->count, e->probability); 570 other_e->count = apply_probability (e->src->count, other_e->probability); 571 count_delta -= e->count; 572 573 /* If latch exists, change its frequency and count, since we changed 574 probability of exit. Theoretically we should update everything from 575 source of exit edge to latch, but for vectorizer this is enough. */ 576 if (loop->latch 577 && loop->latch != e->src) 578 { 579 loop->latch->frequency += freq_delta; 580 if (loop->latch->frequency < 0) 581 loop->latch->frequency = 0; 582 loop->latch->count += count_delta; 583 if (loop->latch->count < 0) 584 loop->latch->count = 0; 585 } 586 } 587 588 /* Roughly speaking we want to reduce the loop body profile by the 589 the difference of loop iterations. We however can do better if 590 we look at the actual profile, if it is available. */ 591 scale = RDIV (iteration_bound * scale, iterations); 592 if (loop->header->count) 593 { 594 gcov_type count_in = 0; 595 596 FOR_EACH_EDGE (e, ei, loop->header->preds) 597 if (e->src != loop->latch) 598 count_in += e->count; 599 600 if (count_in != 0) 601 scale = GCOV_COMPUTE_SCALE (count_in * iteration_bound, 602 loop->header->count); 603 } 604 else if (loop->header->frequency) 605 { 606 int freq_in = 0; 607 608 FOR_EACH_EDGE (e, ei, loop->header->preds) 609 if (e->src != loop->latch) 610 freq_in += EDGE_FREQUENCY (e); 611 612 if (freq_in != 0) 613 scale = GCOV_COMPUTE_SCALE (freq_in * iteration_bound, 614 loop->header->frequency); 615 } 616 if (!scale) 617 scale = 1; 618 } 619 620 if (scale == REG_BR_PROB_BASE) 621 return; 622 623 /* Scale the actual probabilities. */ 624 scale_loop_frequencies (loop, scale, REG_BR_PROB_BASE); 625 if (dump_file && (dump_flags & TDF_DETAILS)) 626 fprintf (dump_file, ";; guessed iterations are now %i\n", 627 (int)expected_loop_iterations_unbounded (loop)); 628} 629 630/* Recompute dominance information for basic blocks outside LOOP. */ 631 632static void 633update_dominators_in_loop (struct loop *loop) 634{ 635 vec<basic_block> dom_bbs = vNULL; 636 sbitmap seen; 637 basic_block *body; 638 unsigned i; 639 640 seen = sbitmap_alloc (last_basic_block_for_fn (cfun)); 641 bitmap_clear (seen); 642 body = get_loop_body (loop); 643 644 for (i = 0; i < loop->num_nodes; i++) 645 bitmap_set_bit (seen, body[i]->index); 646 647 for (i = 0; i < loop->num_nodes; i++) 648 { 649 basic_block ldom; 650 651 for (ldom = first_dom_son (CDI_DOMINATORS, body[i]); 652 ldom; 653 ldom = next_dom_son (CDI_DOMINATORS, ldom)) 654 if (!bitmap_bit_p (seen, ldom->index)) 655 { 656 bitmap_set_bit (seen, ldom->index); 657 dom_bbs.safe_push (ldom); 658 } 659 } 660 661 iterate_fix_dominators (CDI_DOMINATORS, dom_bbs, false); 662 free (body); 663 free (seen); 664 dom_bbs.release (); 665} 666 667/* Creates an if region as shown above. CONDITION is used to create 668 the test for the if. 669 670 | 671 | ------------- ------------- 672 | | pred_bb | | pred_bb | 673 | ------------- ------------- 674 | | | 675 | | | ENTRY_EDGE 676 | | ENTRY_EDGE V 677 | | ====> ------------- 678 | | | cond_bb | 679 | | | CONDITION | 680 | | ------------- 681 | V / \ 682 | ------------- e_false / \ e_true 683 | | succ_bb | V V 684 | ------------- ----------- ----------- 685 | | false_bb | | true_bb | 686 | ----------- ----------- 687 | \ / 688 | \ / 689 | V V 690 | ------------- 691 | | join_bb | 692 | ------------- 693 | | exit_edge (result) 694 | V 695 | ----------- 696 | | succ_bb | 697 | ----------- 698 | 699 */ 700 701edge 702create_empty_if_region_on_edge (edge entry_edge, tree condition) 703{ 704 705 basic_block cond_bb, true_bb, false_bb, join_bb; 706 edge e_true, e_false, exit_edge; 707 gcond *cond_stmt; 708 tree simple_cond; 709 gimple_stmt_iterator gsi; 710 711 cond_bb = split_edge (entry_edge); 712 713 /* Insert condition in cond_bb. */ 714 gsi = gsi_last_bb (cond_bb); 715 simple_cond = 716 force_gimple_operand_gsi (&gsi, condition, true, NULL, 717 false, GSI_NEW_STMT); 718 cond_stmt = gimple_build_cond_from_tree (simple_cond, NULL_TREE, NULL_TREE); 719 gsi = gsi_last_bb (cond_bb); 720 gsi_insert_after (&gsi, cond_stmt, GSI_NEW_STMT); 721 722 join_bb = split_edge (single_succ_edge (cond_bb)); 723 724 e_true = single_succ_edge (cond_bb); 725 true_bb = split_edge (e_true); 726 727 e_false = make_edge (cond_bb, join_bb, 0); 728 false_bb = split_edge (e_false); 729 730 e_true->flags &= ~EDGE_FALLTHRU; 731 e_true->flags |= EDGE_TRUE_VALUE; 732 e_false->flags &= ~EDGE_FALLTHRU; 733 e_false->flags |= EDGE_FALSE_VALUE; 734 735 set_immediate_dominator (CDI_DOMINATORS, cond_bb, entry_edge->src); 736 set_immediate_dominator (CDI_DOMINATORS, true_bb, cond_bb); 737 set_immediate_dominator (CDI_DOMINATORS, false_bb, cond_bb); 738 set_immediate_dominator (CDI_DOMINATORS, join_bb, cond_bb); 739 740 exit_edge = single_succ_edge (join_bb); 741 742 if (single_pred_p (exit_edge->dest)) 743 set_immediate_dominator (CDI_DOMINATORS, exit_edge->dest, join_bb); 744 745 return exit_edge; 746} 747 748/* create_empty_loop_on_edge 749 | 750 | - pred_bb - ------ pred_bb ------ 751 | | | | iv0 = initial_value | 752 | -----|----- ---------|----------- 753 | | ______ | entry_edge 754 | | entry_edge / | | 755 | | ====> | -V---V- loop_header ------------- 756 | V | | iv_before = phi (iv0, iv_after) | 757 | - succ_bb - | ---|----------------------------- 758 | | | | | 759 | ----------- | ---V--- loop_body --------------- 760 | | | iv_after = iv_before + stride | 761 | | | if (iv_before < upper_bound) | 762 | | ---|--------------\-------------- 763 | | | \ exit_e 764 | | V \ 765 | | - loop_latch - V- succ_bb - 766 | | | | | | 767 | | /------------- ----------- 768 | \ ___ / 769 770 Creates an empty loop as shown above, the IV_BEFORE is the SSA_NAME 771 that is used before the increment of IV. IV_BEFORE should be used for 772 adding code to the body that uses the IV. OUTER is the outer loop in 773 which the new loop should be inserted. 774 775 Both INITIAL_VALUE and UPPER_BOUND expressions are gimplified and 776 inserted on the loop entry edge. This implies that this function 777 should be used only when the UPPER_BOUND expression is a loop 778 invariant. */ 779 780struct loop * 781create_empty_loop_on_edge (edge entry_edge, 782 tree initial_value, 783 tree stride, tree upper_bound, 784 tree iv, 785 tree *iv_before, 786 tree *iv_after, 787 struct loop *outer) 788{ 789 basic_block loop_header, loop_latch, succ_bb, pred_bb; 790 struct loop *loop; 791 gimple_stmt_iterator gsi; 792 gimple_seq stmts; 793 gcond *cond_expr; 794 tree exit_test; 795 edge exit_e; 796 int prob; 797 798 gcc_assert (entry_edge && initial_value && stride && upper_bound && iv); 799 800 /* Create header, latch and wire up the loop. */ 801 pred_bb = entry_edge->src; 802 loop_header = split_edge (entry_edge); 803 loop_latch = split_edge (single_succ_edge (loop_header)); 804 succ_bb = single_succ (loop_latch); 805 make_edge (loop_header, succ_bb, 0); 806 redirect_edge_succ_nodup (single_succ_edge (loop_latch), loop_header); 807 808 /* Set immediate dominator information. */ 809 set_immediate_dominator (CDI_DOMINATORS, loop_header, pred_bb); 810 set_immediate_dominator (CDI_DOMINATORS, loop_latch, loop_header); 811 set_immediate_dominator (CDI_DOMINATORS, succ_bb, loop_header); 812 813 /* Initialize a loop structure and put it in a loop hierarchy. */ 814 loop = alloc_loop (); 815 loop->header = loop_header; 816 loop->latch = loop_latch; 817 add_loop (loop, outer); 818 819 /* TODO: Fix frequencies and counts. */ 820 prob = REG_BR_PROB_BASE / 2; 821 822 scale_loop_frequencies (loop, REG_BR_PROB_BASE - prob, REG_BR_PROB_BASE); 823 824 /* Update dominators. */ 825 update_dominators_in_loop (loop); 826 827 /* Modify edge flags. */ 828 exit_e = single_exit (loop); 829 exit_e->flags = EDGE_LOOP_EXIT | EDGE_FALSE_VALUE; 830 single_pred_edge (loop_latch)->flags = EDGE_TRUE_VALUE; 831 832 /* Construct IV code in loop. */ 833 initial_value = force_gimple_operand (initial_value, &stmts, true, iv); 834 if (stmts) 835 { 836 gsi_insert_seq_on_edge (loop_preheader_edge (loop), stmts); 837 gsi_commit_edge_inserts (); 838 } 839 840 upper_bound = force_gimple_operand (upper_bound, &stmts, true, NULL); 841 if (stmts) 842 { 843 gsi_insert_seq_on_edge (loop_preheader_edge (loop), stmts); 844 gsi_commit_edge_inserts (); 845 } 846 847 gsi = gsi_last_bb (loop_header); 848 create_iv (initial_value, stride, iv, loop, &gsi, false, 849 iv_before, iv_after); 850 851 /* Insert loop exit condition. */ 852 cond_expr = gimple_build_cond 853 (LT_EXPR, *iv_before, upper_bound, NULL_TREE, NULL_TREE); 854 855 exit_test = gimple_cond_lhs (cond_expr); 856 exit_test = force_gimple_operand_gsi (&gsi, exit_test, true, NULL, 857 false, GSI_NEW_STMT); 858 gimple_cond_set_lhs (cond_expr, exit_test); 859 gsi = gsi_last_bb (exit_e->src); 860 gsi_insert_after (&gsi, cond_expr, GSI_NEW_STMT); 861 862 split_block_after_labels (loop_header); 863 864 return loop; 865} 866 867/* Make area between HEADER_EDGE and LATCH_EDGE a loop by connecting 868 latch to header and update loop tree and dominators 869 accordingly. Everything between them plus LATCH_EDGE destination must 870 be dominated by HEADER_EDGE destination, and back-reachable from 871 LATCH_EDGE source. HEADER_EDGE is redirected to basic block SWITCH_BB, 872 FALSE_EDGE of SWITCH_BB to original destination of HEADER_EDGE and 873 TRUE_EDGE of SWITCH_BB to original destination of LATCH_EDGE. 874 Returns the newly created loop. Frequencies and counts in the new loop 875 are scaled by FALSE_SCALE and in the old one by TRUE_SCALE. */ 876 877struct loop * 878loopify (edge latch_edge, edge header_edge, 879 basic_block switch_bb, edge true_edge, edge false_edge, 880 bool redirect_all_edges, unsigned true_scale, unsigned false_scale) 881{ 882 basic_block succ_bb = latch_edge->dest; 883 basic_block pred_bb = header_edge->src; 884 struct loop *loop = alloc_loop (); 885 struct loop *outer = loop_outer (succ_bb->loop_father); 886 int freq; 887 gcov_type cnt; 888 edge e; 889 edge_iterator ei; 890 891 loop->header = header_edge->dest; 892 loop->latch = latch_edge->src; 893 894 freq = EDGE_FREQUENCY (header_edge); 895 cnt = header_edge->count; 896 897 /* Redirect edges. */ 898 loop_redirect_edge (latch_edge, loop->header); 899 loop_redirect_edge (true_edge, succ_bb); 900 901 /* During loop versioning, one of the switch_bb edge is already properly 902 set. Do not redirect it again unless redirect_all_edges is true. */ 903 if (redirect_all_edges) 904 { 905 loop_redirect_edge (header_edge, switch_bb); 906 loop_redirect_edge (false_edge, loop->header); 907 908 /* Update dominators. */ 909 set_immediate_dominator (CDI_DOMINATORS, switch_bb, pred_bb); 910 set_immediate_dominator (CDI_DOMINATORS, loop->header, switch_bb); 911 } 912 913 set_immediate_dominator (CDI_DOMINATORS, succ_bb, switch_bb); 914 915 /* Compute new loop. */ 916 add_loop (loop, outer); 917 918 /* Add switch_bb to appropriate loop. */ 919 if (switch_bb->loop_father) 920 remove_bb_from_loops (switch_bb); 921 add_bb_to_loop (switch_bb, outer); 922 923 /* Fix frequencies. */ 924 if (redirect_all_edges) 925 { 926 switch_bb->frequency = freq; 927 switch_bb->count = cnt; 928 FOR_EACH_EDGE (e, ei, switch_bb->succs) 929 { 930 e->count = apply_probability (switch_bb->count, e->probability); 931 } 932 } 933 scale_loop_frequencies (loop, false_scale, REG_BR_PROB_BASE); 934 scale_loop_frequencies (succ_bb->loop_father, true_scale, REG_BR_PROB_BASE); 935 update_dominators_in_loop (loop); 936 937 return loop; 938} 939 940/* Remove the latch edge of a LOOP and update loops to indicate that 941 the LOOP was removed. After this function, original loop latch will 942 have no successor, which caller is expected to fix somehow. 943 944 If this may cause the information about irreducible regions to become 945 invalid, IRRED_INVALIDATED is set to true. 946 947 LOOP_CLOSED_SSA_INVALIDATED, if non-NULL, is a bitmap where we store 948 basic blocks that had non-trivial update on their loop_father.*/ 949 950void 951unloop (struct loop *loop, bool *irred_invalidated, 952 bitmap loop_closed_ssa_invalidated) 953{ 954 basic_block *body; 955 struct loop *ploop; 956 unsigned i, n; 957 basic_block latch = loop->latch; 958 bool dummy = false; 959 960 if (loop_preheader_edge (loop)->flags & EDGE_IRREDUCIBLE_LOOP) 961 *irred_invalidated = true; 962 963 /* This is relatively straightforward. The dominators are unchanged, as 964 loop header dominates loop latch, so the only thing we have to care of 965 is the placement of loops and basic blocks inside the loop tree. We 966 move them all to the loop->outer, and then let fix_bb_placements do 967 its work. */ 968 969 body = get_loop_body (loop); 970 n = loop->num_nodes; 971 for (i = 0; i < n; i++) 972 if (body[i]->loop_father == loop) 973 { 974 remove_bb_from_loops (body[i]); 975 add_bb_to_loop (body[i], loop_outer (loop)); 976 } 977 free (body); 978 979 while (loop->inner) 980 { 981 ploop = loop->inner; 982 flow_loop_tree_node_remove (ploop); 983 flow_loop_tree_node_add (loop_outer (loop), ploop); 984 } 985 986 /* Remove the loop and free its data. */ 987 delete_loop (loop); 988 989 remove_edge (single_succ_edge (latch)); 990 991 /* We do not pass IRRED_INVALIDATED to fix_bb_placements here, as even if 992 there is an irreducible region inside the cancelled loop, the flags will 993 be still correct. */ 994 fix_bb_placements (latch, &dummy, loop_closed_ssa_invalidated); 995} 996 997/* Fix placement of superloops of LOOP inside loop tree, i.e. ensure that 998 condition stated in description of fix_loop_placement holds for them. 999 It is used in case when we removed some edges coming out of LOOP, which 1000 may cause the right placement of LOOP inside loop tree to change. 1001 1002 IRRED_INVALIDATED is set to true if a change in the loop structures might 1003 invalidate the information about irreducible regions. */ 1004 1005static void 1006fix_loop_placements (struct loop *loop, bool *irred_invalidated) 1007{ 1008 struct loop *outer; 1009 1010 while (loop_outer (loop)) 1011 { 1012 outer = loop_outer (loop); 1013 if (!fix_loop_placement (loop, irred_invalidated)) 1014 break; 1015 1016 /* Changing the placement of a loop in the loop tree may alter the 1017 validity of condition 2) of the description of fix_bb_placement 1018 for its preheader, because the successor is the header and belongs 1019 to the loop. So call fix_bb_placements to fix up the placement 1020 of the preheader and (possibly) of its predecessors. */ 1021 fix_bb_placements (loop_preheader_edge (loop)->src, 1022 irred_invalidated, NULL); 1023 loop = outer; 1024 } 1025} 1026 1027/* Duplicate loop bounds and other information we store about 1028 the loop into its duplicate. */ 1029 1030void 1031copy_loop_info (struct loop *loop, struct loop *target) 1032{ 1033 gcc_checking_assert (!target->any_upper_bound && !target->any_estimate); 1034 target->any_upper_bound = loop->any_upper_bound; 1035 target->nb_iterations_upper_bound = loop->nb_iterations_upper_bound; 1036 target->any_estimate = loop->any_estimate; 1037 target->nb_iterations_estimate = loop->nb_iterations_estimate; 1038 target->estimate_state = loop->estimate_state; 1039 target->warned_aggressive_loop_optimizations 1040 |= loop->warned_aggressive_loop_optimizations; 1041} 1042 1043/* Copies copy of LOOP as subloop of TARGET loop, placing newly 1044 created loop into loops structure. */ 1045struct loop * 1046duplicate_loop (struct loop *loop, struct loop *target) 1047{ 1048 struct loop *cloop; 1049 cloop = alloc_loop (); 1050 place_new_loop (cfun, cloop); 1051 1052 copy_loop_info (loop, cloop); 1053 1054 /* Mark the new loop as copy of LOOP. */ 1055 set_loop_copy (loop, cloop); 1056 1057 /* Add it to target. */ 1058 flow_loop_tree_node_add (target, cloop); 1059 1060 return cloop; 1061} 1062 1063/* Copies structure of subloops of LOOP into TARGET loop, placing 1064 newly created loops into loop tree. */ 1065void 1066duplicate_subloops (struct loop *loop, struct loop *target) 1067{ 1068 struct loop *aloop, *cloop; 1069 1070 for (aloop = loop->inner; aloop; aloop = aloop->next) 1071 { 1072 cloop = duplicate_loop (aloop, target); 1073 duplicate_subloops (aloop, cloop); 1074 } 1075} 1076 1077/* Copies structure of subloops of N loops, stored in array COPIED_LOOPS, 1078 into TARGET loop, placing newly created loops into loop tree. */ 1079static void 1080copy_loops_to (struct loop **copied_loops, int n, struct loop *target) 1081{ 1082 struct loop *aloop; 1083 int i; 1084 1085 for (i = 0; i < n; i++) 1086 { 1087 aloop = duplicate_loop (copied_loops[i], target); 1088 duplicate_subloops (copied_loops[i], aloop); 1089 } 1090} 1091 1092/* Redirects edge E to basic block DEST. */ 1093static void 1094loop_redirect_edge (edge e, basic_block dest) 1095{ 1096 if (e->dest == dest) 1097 return; 1098 1099 redirect_edge_and_branch_force (e, dest); 1100} 1101 1102/* Check whether LOOP's body can be duplicated. */ 1103bool 1104can_duplicate_loop_p (const struct loop *loop) 1105{ 1106 int ret; 1107 basic_block *bbs = get_loop_body (loop); 1108 1109 ret = can_copy_bbs_p (bbs, loop->num_nodes); 1110 free (bbs); 1111 1112 return ret; 1113} 1114 1115/* Sets probability and count of edge E to zero. The probability and count 1116 is redistributed evenly to the remaining edges coming from E->src. */ 1117 1118static void 1119set_zero_probability (edge e) 1120{ 1121 basic_block bb = e->src; 1122 edge_iterator ei; 1123 edge ae, last = NULL; 1124 unsigned n = EDGE_COUNT (bb->succs); 1125 gcov_type cnt = e->count, cnt1; 1126 unsigned prob = e->probability, prob1; 1127 1128 gcc_assert (n > 1); 1129 cnt1 = cnt / (n - 1); 1130 prob1 = prob / (n - 1); 1131 1132 FOR_EACH_EDGE (ae, ei, bb->succs) 1133 { 1134 if (ae == e) 1135 continue; 1136 1137 ae->probability += prob1; 1138 ae->count += cnt1; 1139 last = ae; 1140 } 1141 1142 /* Move the rest to one of the edges. */ 1143 last->probability += prob % (n - 1); 1144 last->count += cnt % (n - 1); 1145 1146 e->probability = 0; 1147 e->count = 0; 1148} 1149 1150/* Duplicates body of LOOP to given edge E NDUPL times. Takes care of updating 1151 loop structure and dominators. E's destination must be LOOP header for 1152 this to work, i.e. it must be entry or latch edge of this loop; these are 1153 unique, as the loops must have preheaders for this function to work 1154 correctly (in case E is latch, the function unrolls the loop, if E is entry 1155 edge, it peels the loop). Store edges created by copying ORIG edge from 1156 copies corresponding to set bits in WONT_EXIT bitmap (bit 0 corresponds to 1157 original LOOP body, the other copies are numbered in order given by control 1158 flow through them) into TO_REMOVE array. Returns false if duplication is 1159 impossible. */ 1160 1161bool 1162duplicate_loop_to_header_edge (struct loop *loop, edge e, 1163 unsigned int ndupl, sbitmap wont_exit, 1164 edge orig, vec<edge> *to_remove, 1165 int flags) 1166{ 1167 struct loop *target, *aloop; 1168 struct loop **orig_loops; 1169 unsigned n_orig_loops; 1170 basic_block header = loop->header, latch = loop->latch; 1171 basic_block *new_bbs, *bbs, *first_active; 1172 basic_block new_bb, bb, first_active_latch = NULL; 1173 edge ae, latch_edge; 1174 edge spec_edges[2], new_spec_edges[2]; 1175#define SE_LATCH 0 1176#define SE_ORIG 1 1177 unsigned i, j, n; 1178 int is_latch = (latch == e->src); 1179 int scale_act = 0, *scale_step = NULL, scale_main = 0; 1180 int scale_after_exit = 0; 1181 int p, freq_in, freq_le, freq_out_orig; 1182 int prob_pass_thru, prob_pass_wont_exit, prob_pass_main; 1183 int add_irreducible_flag; 1184 basic_block place_after; 1185 bitmap bbs_to_scale = NULL; 1186 bitmap_iterator bi; 1187 1188 gcc_assert (e->dest == loop->header); 1189 gcc_assert (ndupl > 0); 1190 1191 if (orig) 1192 { 1193 /* Orig must be edge out of the loop. */ 1194 gcc_assert (flow_bb_inside_loop_p (loop, orig->src)); 1195 gcc_assert (!flow_bb_inside_loop_p (loop, orig->dest)); 1196 } 1197 1198 n = loop->num_nodes; 1199 bbs = get_loop_body_in_dom_order (loop); 1200 gcc_assert (bbs[0] == loop->header); 1201 gcc_assert (bbs[n - 1] == loop->latch); 1202 1203 /* Check whether duplication is possible. */ 1204 if (!can_copy_bbs_p (bbs, loop->num_nodes)) 1205 { 1206 free (bbs); 1207 return false; 1208 } 1209 new_bbs = XNEWVEC (basic_block, loop->num_nodes); 1210 1211 /* In case we are doing loop peeling and the loop is in the middle of 1212 irreducible region, the peeled copies will be inside it too. */ 1213 add_irreducible_flag = e->flags & EDGE_IRREDUCIBLE_LOOP; 1214 gcc_assert (!is_latch || !add_irreducible_flag); 1215 1216 /* Find edge from latch. */ 1217 latch_edge = loop_latch_edge (loop); 1218 1219 if (flags & DLTHE_FLAG_UPDATE_FREQ) 1220 { 1221 /* Calculate coefficients by that we have to scale frequencies 1222 of duplicated loop bodies. */ 1223 freq_in = header->frequency; 1224 freq_le = EDGE_FREQUENCY (latch_edge); 1225 if (freq_in == 0) 1226 freq_in = 1; 1227 if (freq_in < freq_le) 1228 freq_in = freq_le; 1229 freq_out_orig = orig ? EDGE_FREQUENCY (orig) : freq_in - freq_le; 1230 if (freq_out_orig > freq_in - freq_le) 1231 freq_out_orig = freq_in - freq_le; 1232 prob_pass_thru = RDIV (REG_BR_PROB_BASE * freq_le, freq_in); 1233 prob_pass_wont_exit = 1234 RDIV (REG_BR_PROB_BASE * (freq_le + freq_out_orig), freq_in); 1235 1236 if (orig 1237 && REG_BR_PROB_BASE - orig->probability != 0) 1238 { 1239 /* The blocks that are dominated by a removed exit edge ORIG have 1240 frequencies scaled by this. */ 1241 scale_after_exit 1242 = GCOV_COMPUTE_SCALE (REG_BR_PROB_BASE, 1243 REG_BR_PROB_BASE - orig->probability); 1244 bbs_to_scale = BITMAP_ALLOC (NULL); 1245 for (i = 0; i < n; i++) 1246 { 1247 if (bbs[i] != orig->src 1248 && dominated_by_p (CDI_DOMINATORS, bbs[i], orig->src)) 1249 bitmap_set_bit (bbs_to_scale, i); 1250 } 1251 } 1252 1253 scale_step = XNEWVEC (int, ndupl); 1254 1255 for (i = 1; i <= ndupl; i++) 1256 scale_step[i - 1] = bitmap_bit_p (wont_exit, i) 1257 ? prob_pass_wont_exit 1258 : prob_pass_thru; 1259 1260 /* Complete peeling is special as the probability of exit in last 1261 copy becomes 1. */ 1262 if (flags & DLTHE_FLAG_COMPLETTE_PEEL) 1263 { 1264 int wanted_freq = EDGE_FREQUENCY (e); 1265 1266 if (wanted_freq > freq_in) 1267 wanted_freq = freq_in; 1268 1269 gcc_assert (!is_latch); 1270 /* First copy has frequency of incoming edge. Each subsequent 1271 frequency should be reduced by prob_pass_wont_exit. Caller 1272 should've managed the flags so all except for original loop 1273 has won't exist set. */ 1274 scale_act = GCOV_COMPUTE_SCALE (wanted_freq, freq_in); 1275 /* Now simulate the duplication adjustments and compute header 1276 frequency of the last copy. */ 1277 for (i = 0; i < ndupl; i++) 1278 wanted_freq = combine_probabilities (wanted_freq, scale_step[i]); 1279 scale_main = GCOV_COMPUTE_SCALE (wanted_freq, freq_in); 1280 } 1281 else if (is_latch) 1282 { 1283 prob_pass_main = bitmap_bit_p (wont_exit, 0) 1284 ? prob_pass_wont_exit 1285 : prob_pass_thru; 1286 p = prob_pass_main; 1287 scale_main = REG_BR_PROB_BASE; 1288 for (i = 0; i < ndupl; i++) 1289 { 1290 scale_main += p; 1291 p = combine_probabilities (p, scale_step[i]); 1292 } 1293 scale_main = GCOV_COMPUTE_SCALE (REG_BR_PROB_BASE, scale_main); 1294 scale_act = combine_probabilities (scale_main, prob_pass_main); 1295 } 1296 else 1297 { 1298 scale_main = REG_BR_PROB_BASE; 1299 for (i = 0; i < ndupl; i++) 1300 scale_main = combine_probabilities (scale_main, scale_step[i]); 1301 scale_act = REG_BR_PROB_BASE - prob_pass_thru; 1302 } 1303 for (i = 0; i < ndupl; i++) 1304 gcc_assert (scale_step[i] >= 0 && scale_step[i] <= REG_BR_PROB_BASE); 1305 gcc_assert (scale_main >= 0 && scale_main <= REG_BR_PROB_BASE 1306 && scale_act >= 0 && scale_act <= REG_BR_PROB_BASE); 1307 } 1308 1309 /* Loop the new bbs will belong to. */ 1310 target = e->src->loop_father; 1311 1312 /* Original loops. */ 1313 n_orig_loops = 0; 1314 for (aloop = loop->inner; aloop; aloop = aloop->next) 1315 n_orig_loops++; 1316 orig_loops = XNEWVEC (struct loop *, n_orig_loops); 1317 for (aloop = loop->inner, i = 0; aloop; aloop = aloop->next, i++) 1318 orig_loops[i] = aloop; 1319 1320 set_loop_copy (loop, target); 1321 1322 first_active = XNEWVEC (basic_block, n); 1323 if (is_latch) 1324 { 1325 memcpy (first_active, bbs, n * sizeof (basic_block)); 1326 first_active_latch = latch; 1327 } 1328 1329 spec_edges[SE_ORIG] = orig; 1330 spec_edges[SE_LATCH] = latch_edge; 1331 1332 place_after = e->src; 1333 for (j = 0; j < ndupl; j++) 1334 { 1335 /* Copy loops. */ 1336 copy_loops_to (orig_loops, n_orig_loops, target); 1337 1338 /* Copy bbs. */ 1339 copy_bbs (bbs, n, new_bbs, spec_edges, 2, new_spec_edges, loop, 1340 place_after, true); 1341 place_after = new_spec_edges[SE_LATCH]->src; 1342 1343 if (flags & DLTHE_RECORD_COPY_NUMBER) 1344 for (i = 0; i < n; i++) 1345 { 1346 gcc_assert (!new_bbs[i]->aux); 1347 new_bbs[i]->aux = (void *)(size_t)(j + 1); 1348 } 1349 1350 /* Note whether the blocks and edges belong to an irreducible loop. */ 1351 if (add_irreducible_flag) 1352 { 1353 for (i = 0; i < n; i++) 1354 new_bbs[i]->flags |= BB_DUPLICATED; 1355 for (i = 0; i < n; i++) 1356 { 1357 edge_iterator ei; 1358 new_bb = new_bbs[i]; 1359 if (new_bb->loop_father == target) 1360 new_bb->flags |= BB_IRREDUCIBLE_LOOP; 1361 1362 FOR_EACH_EDGE (ae, ei, new_bb->succs) 1363 if ((ae->dest->flags & BB_DUPLICATED) 1364 && (ae->src->loop_father == target 1365 || ae->dest->loop_father == target)) 1366 ae->flags |= EDGE_IRREDUCIBLE_LOOP; 1367 } 1368 for (i = 0; i < n; i++) 1369 new_bbs[i]->flags &= ~BB_DUPLICATED; 1370 } 1371 1372 /* Redirect the special edges. */ 1373 if (is_latch) 1374 { 1375 redirect_edge_and_branch_force (latch_edge, new_bbs[0]); 1376 redirect_edge_and_branch_force (new_spec_edges[SE_LATCH], 1377 loop->header); 1378 set_immediate_dominator (CDI_DOMINATORS, new_bbs[0], latch); 1379 latch = loop->latch = new_bbs[n - 1]; 1380 e = latch_edge = new_spec_edges[SE_LATCH]; 1381 } 1382 else 1383 { 1384 redirect_edge_and_branch_force (new_spec_edges[SE_LATCH], 1385 loop->header); 1386 redirect_edge_and_branch_force (e, new_bbs[0]); 1387 set_immediate_dominator (CDI_DOMINATORS, new_bbs[0], e->src); 1388 e = new_spec_edges[SE_LATCH]; 1389 } 1390 1391 /* Record exit edge in this copy. */ 1392 if (orig && bitmap_bit_p (wont_exit, j + 1)) 1393 { 1394 if (to_remove) 1395 to_remove->safe_push (new_spec_edges[SE_ORIG]); 1396 set_zero_probability (new_spec_edges[SE_ORIG]); 1397 1398 /* Scale the frequencies of the blocks dominated by the exit. */ 1399 if (bbs_to_scale) 1400 { 1401 EXECUTE_IF_SET_IN_BITMAP (bbs_to_scale, 0, i, bi) 1402 { 1403 scale_bbs_frequencies_int (new_bbs + i, 1, scale_after_exit, 1404 REG_BR_PROB_BASE); 1405 } 1406 } 1407 } 1408 1409 /* Record the first copy in the control flow order if it is not 1410 the original loop (i.e. in case of peeling). */ 1411 if (!first_active_latch) 1412 { 1413 memcpy (first_active, new_bbs, n * sizeof (basic_block)); 1414 first_active_latch = new_bbs[n - 1]; 1415 } 1416 1417 /* Set counts and frequencies. */ 1418 if (flags & DLTHE_FLAG_UPDATE_FREQ) 1419 { 1420 scale_bbs_frequencies_int (new_bbs, n, scale_act, REG_BR_PROB_BASE); 1421 scale_act = combine_probabilities (scale_act, scale_step[j]); 1422 } 1423 } 1424 free (new_bbs); 1425 free (orig_loops); 1426 1427 /* Record the exit edge in the original loop body, and update the frequencies. */ 1428 if (orig && bitmap_bit_p (wont_exit, 0)) 1429 { 1430 if (to_remove) 1431 to_remove->safe_push (orig); 1432 set_zero_probability (orig); 1433 1434 /* Scale the frequencies of the blocks dominated by the exit. */ 1435 if (bbs_to_scale) 1436 { 1437 EXECUTE_IF_SET_IN_BITMAP (bbs_to_scale, 0, i, bi) 1438 { 1439 scale_bbs_frequencies_int (bbs + i, 1, scale_after_exit, 1440 REG_BR_PROB_BASE); 1441 } 1442 } 1443 } 1444 1445 /* Update the original loop. */ 1446 if (!is_latch) 1447 set_immediate_dominator (CDI_DOMINATORS, e->dest, e->src); 1448 if (flags & DLTHE_FLAG_UPDATE_FREQ) 1449 { 1450 scale_bbs_frequencies_int (bbs, n, scale_main, REG_BR_PROB_BASE); 1451 free (scale_step); 1452 } 1453 1454 /* Update dominators of outer blocks if affected. */ 1455 for (i = 0; i < n; i++) 1456 { 1457 basic_block dominated, dom_bb; 1458 vec<basic_block> dom_bbs; 1459 unsigned j; 1460 1461 bb = bbs[i]; 1462 bb->aux = 0; 1463 1464 dom_bbs = get_dominated_by (CDI_DOMINATORS, bb); 1465 FOR_EACH_VEC_ELT (dom_bbs, j, dominated) 1466 { 1467 if (flow_bb_inside_loop_p (loop, dominated)) 1468 continue; 1469 dom_bb = nearest_common_dominator ( 1470 CDI_DOMINATORS, first_active[i], first_active_latch); 1471 set_immediate_dominator (CDI_DOMINATORS, dominated, dom_bb); 1472 } 1473 dom_bbs.release (); 1474 } 1475 free (first_active); 1476 1477 free (bbs); 1478 BITMAP_FREE (bbs_to_scale); 1479 1480 return true; 1481} 1482 1483/* A callback for make_forwarder block, to redirect all edges except for 1484 MFB_KJ_EDGE to the entry part. E is the edge for that we should decide 1485 whether to redirect it. */ 1486 1487edge mfb_kj_edge; 1488bool 1489mfb_keep_just (edge e) 1490{ 1491 return e != mfb_kj_edge; 1492} 1493 1494/* True when a candidate preheader BLOCK has predecessors from LOOP. */ 1495 1496static bool 1497has_preds_from_loop (basic_block block, struct loop *loop) 1498{ 1499 edge e; 1500 edge_iterator ei; 1501 1502 FOR_EACH_EDGE (e, ei, block->preds) 1503 if (e->src->loop_father == loop) 1504 return true; 1505 return false; 1506} 1507 1508/* Creates a pre-header for a LOOP. Returns newly created block. Unless 1509 CP_SIMPLE_PREHEADERS is set in FLAGS, we only force LOOP to have single 1510 entry; otherwise we also force preheader block to have only one successor. 1511 When CP_FALLTHRU_PREHEADERS is set in FLAGS, we force the preheader block 1512 to be a fallthru predecessor to the loop header and to have only 1513 predecessors from outside of the loop. 1514 The function also updates dominators. */ 1515 1516basic_block 1517create_preheader (struct loop *loop, int flags) 1518{ 1519 edge e, fallthru; 1520 basic_block dummy; 1521 int nentry = 0; 1522 bool irred = false; 1523 bool latch_edge_was_fallthru; 1524 edge one_succ_pred = NULL, single_entry = NULL; 1525 edge_iterator ei; 1526 1527 FOR_EACH_EDGE (e, ei, loop->header->preds) 1528 { 1529 if (e->src == loop->latch) 1530 continue; 1531 irred |= (e->flags & EDGE_IRREDUCIBLE_LOOP) != 0; 1532 nentry++; 1533 single_entry = e; 1534 if (single_succ_p (e->src)) 1535 one_succ_pred = e; 1536 } 1537 gcc_assert (nentry); 1538 if (nentry == 1) 1539 { 1540 bool need_forwarder_block = false; 1541 1542 /* We do not allow entry block to be the loop preheader, since we 1543 cannot emit code there. */ 1544 if (single_entry->src == ENTRY_BLOCK_PTR_FOR_FN (cfun)) 1545 need_forwarder_block = true; 1546 else 1547 { 1548 /* If we want simple preheaders, also force the preheader to have 1549 just a single successor. */ 1550 if ((flags & CP_SIMPLE_PREHEADERS) 1551 && !single_succ_p (single_entry->src)) 1552 need_forwarder_block = true; 1553 /* If we want fallthru preheaders, also create forwarder block when 1554 preheader ends with a jump or has predecessors from loop. */ 1555 else if ((flags & CP_FALLTHRU_PREHEADERS) 1556 && (JUMP_P (BB_END (single_entry->src)) 1557 || has_preds_from_loop (single_entry->src, loop))) 1558 need_forwarder_block = true; 1559 } 1560 if (! need_forwarder_block) 1561 return NULL; 1562 } 1563 1564 mfb_kj_edge = loop_latch_edge (loop); 1565 latch_edge_was_fallthru = (mfb_kj_edge->flags & EDGE_FALLTHRU) != 0; 1566 fallthru = make_forwarder_block (loop->header, mfb_keep_just, NULL); 1567 dummy = fallthru->src; 1568 loop->header = fallthru->dest; 1569 1570 /* Try to be clever in placing the newly created preheader. The idea is to 1571 avoid breaking any "fallthruness" relationship between blocks. 1572 1573 The preheader was created just before the header and all incoming edges 1574 to the header were redirected to the preheader, except the latch edge. 1575 So the only problematic case is when this latch edge was a fallthru 1576 edge: it is not anymore after the preheader creation so we have broken 1577 the fallthruness. We're therefore going to look for a better place. */ 1578 if (latch_edge_was_fallthru) 1579 { 1580 if (one_succ_pred) 1581 e = one_succ_pred; 1582 else 1583 e = EDGE_PRED (dummy, 0); 1584 1585 move_block_after (dummy, e->src); 1586 } 1587 1588 if (irred) 1589 { 1590 dummy->flags |= BB_IRREDUCIBLE_LOOP; 1591 single_succ_edge (dummy)->flags |= EDGE_IRREDUCIBLE_LOOP; 1592 } 1593 1594 if (dump_file) 1595 fprintf (dump_file, "Created preheader block for loop %i\n", 1596 loop->num); 1597 1598 if (flags & CP_FALLTHRU_PREHEADERS) 1599 gcc_assert ((single_succ_edge (dummy)->flags & EDGE_FALLTHRU) 1600 && !JUMP_P (BB_END (dummy))); 1601 1602 return dummy; 1603} 1604 1605/* Create preheaders for each loop; for meaning of FLAGS see create_preheader. */ 1606 1607void 1608create_preheaders (int flags) 1609{ 1610 struct loop *loop; 1611 1612 if (!current_loops) 1613 return; 1614 1615 FOR_EACH_LOOP (loop, 0) 1616 create_preheader (loop, flags); 1617 loops_state_set (LOOPS_HAVE_PREHEADERS); 1618} 1619 1620/* Forces all loop latches to have only single successor. */ 1621 1622void 1623force_single_succ_latches (void) 1624{ 1625 struct loop *loop; 1626 edge e; 1627 1628 FOR_EACH_LOOP (loop, 0) 1629 { 1630 if (loop->latch != loop->header && single_succ_p (loop->latch)) 1631 continue; 1632 1633 e = find_edge (loop->latch, loop->header); 1634 gcc_checking_assert (e != NULL); 1635 1636 split_edge (e); 1637 } 1638 loops_state_set (LOOPS_HAVE_SIMPLE_LATCHES); 1639} 1640 1641/* This function is called from loop_version. It splits the entry edge 1642 of the loop we want to version, adds the versioning condition, and 1643 adjust the edges to the two versions of the loop appropriately. 1644 e is an incoming edge. Returns the basic block containing the 1645 condition. 1646 1647 --- edge e ---- > [second_head] 1648 1649 Split it and insert new conditional expression and adjust edges. 1650 1651 --- edge e ---> [cond expr] ---> [first_head] 1652 | 1653 +---------> [second_head] 1654 1655 THEN_PROB is the probability of then branch of the condition. */ 1656 1657static basic_block 1658lv_adjust_loop_entry_edge (basic_block first_head, basic_block second_head, 1659 edge e, void *cond_expr, unsigned then_prob) 1660{ 1661 basic_block new_head = NULL; 1662 edge e1; 1663 1664 gcc_assert (e->dest == second_head); 1665 1666 /* Split edge 'e'. This will create a new basic block, where we can 1667 insert conditional expr. */ 1668 new_head = split_edge (e); 1669 1670 lv_add_condition_to_bb (first_head, second_head, new_head, 1671 cond_expr); 1672 1673 /* Don't set EDGE_TRUE_VALUE in RTL mode, as it's invalid there. */ 1674 e = single_succ_edge (new_head); 1675 e1 = make_edge (new_head, first_head, 1676 current_ir_type () == IR_GIMPLE ? EDGE_TRUE_VALUE : 0); 1677 e1->probability = then_prob; 1678 e->probability = REG_BR_PROB_BASE - then_prob; 1679 e1->count = apply_probability (e->count, e1->probability); 1680 e->count = apply_probability (e->count, e->probability); 1681 1682 set_immediate_dominator (CDI_DOMINATORS, first_head, new_head); 1683 set_immediate_dominator (CDI_DOMINATORS, second_head, new_head); 1684 1685 /* Adjust loop header phi nodes. */ 1686 lv_adjust_loop_header_phi (first_head, second_head, new_head, e1); 1687 1688 return new_head; 1689} 1690 1691/* Main entry point for Loop Versioning transformation. 1692 1693 This transformation given a condition and a loop, creates 1694 -if (condition) { loop_copy1 } else { loop_copy2 }, 1695 where loop_copy1 is the loop transformed in one way, and loop_copy2 1696 is the loop transformed in another way (or unchanged). 'condition' 1697 may be a run time test for things that were not resolved by static 1698 analysis (overlapping ranges (anti-aliasing), alignment, etc.). 1699 1700 THEN_PROB is the probability of the then edge of the if. THEN_SCALE 1701 is the ratio by that the frequencies in the original loop should 1702 be scaled. ELSE_SCALE is the ratio by that the frequencies in the 1703 new loop should be scaled. 1704 1705 If PLACE_AFTER is true, we place the new loop after LOOP in the 1706 instruction stream, otherwise it is placed before LOOP. */ 1707 1708struct loop * 1709loop_version (struct loop *loop, 1710 void *cond_expr, basic_block *condition_bb, 1711 unsigned then_prob, unsigned then_scale, unsigned else_scale, 1712 bool place_after) 1713{ 1714 basic_block first_head, second_head; 1715 edge entry, latch_edge, true_edge, false_edge; 1716 int irred_flag; 1717 struct loop *nloop; 1718 basic_block cond_bb; 1719 1720 /* Record entry and latch edges for the loop */ 1721 entry = loop_preheader_edge (loop); 1722 irred_flag = entry->flags & EDGE_IRREDUCIBLE_LOOP; 1723 entry->flags &= ~EDGE_IRREDUCIBLE_LOOP; 1724 1725 /* Note down head of loop as first_head. */ 1726 first_head = entry->dest; 1727 1728 /* Duplicate loop. */ 1729 if (!cfg_hook_duplicate_loop_to_header_edge (loop, entry, 1, 1730 NULL, NULL, NULL, 0)) 1731 { 1732 entry->flags |= irred_flag; 1733 return NULL; 1734 } 1735 1736 /* After duplication entry edge now points to new loop head block. 1737 Note down new head as second_head. */ 1738 second_head = entry->dest; 1739 1740 /* Split loop entry edge and insert new block with cond expr. */ 1741 cond_bb = lv_adjust_loop_entry_edge (first_head, second_head, 1742 entry, cond_expr, then_prob); 1743 if (condition_bb) 1744 *condition_bb = cond_bb; 1745 1746 if (!cond_bb) 1747 { 1748 entry->flags |= irred_flag; 1749 return NULL; 1750 } 1751 1752 latch_edge = single_succ_edge (get_bb_copy (loop->latch)); 1753 1754 extract_cond_bb_edges (cond_bb, &true_edge, &false_edge); 1755 nloop = loopify (latch_edge, 1756 single_pred_edge (get_bb_copy (loop->header)), 1757 cond_bb, true_edge, false_edge, 1758 false /* Do not redirect all edges. */, 1759 then_scale, else_scale); 1760 1761 copy_loop_info (loop, nloop); 1762 1763 /* loopify redirected latch_edge. Update its PENDING_STMTS. */ 1764 lv_flush_pending_stmts (latch_edge); 1765 1766 /* loopify redirected condition_bb's succ edge. Update its PENDING_STMTS. */ 1767 extract_cond_bb_edges (cond_bb, &true_edge, &false_edge); 1768 lv_flush_pending_stmts (false_edge); 1769 /* Adjust irreducible flag. */ 1770 if (irred_flag) 1771 { 1772 cond_bb->flags |= BB_IRREDUCIBLE_LOOP; 1773 loop_preheader_edge (loop)->flags |= EDGE_IRREDUCIBLE_LOOP; 1774 loop_preheader_edge (nloop)->flags |= EDGE_IRREDUCIBLE_LOOP; 1775 single_pred_edge (cond_bb)->flags |= EDGE_IRREDUCIBLE_LOOP; 1776 } 1777 1778 if (place_after) 1779 { 1780 basic_block *bbs = get_loop_body_in_dom_order (nloop), after; 1781 unsigned i; 1782 1783 after = loop->latch; 1784 1785 for (i = 0; i < nloop->num_nodes; i++) 1786 { 1787 move_block_after (bbs[i], after); 1788 after = bbs[i]; 1789 } 1790 free (bbs); 1791 } 1792 1793 /* At this point condition_bb is loop preheader with two successors, 1794 first_head and second_head. Make sure that loop preheader has only 1795 one successor. */ 1796 split_edge (loop_preheader_edge (loop)); 1797 split_edge (loop_preheader_edge (nloop)); 1798 1799 return nloop; 1800} 1801