1 /* Full and partial redundancy elimination and code hoisting on SSA GIMPLE. 2 Copyright (C) 2001-2017 Free Software Foundation, Inc. 3 Contributed by Daniel Berlin <dan@dberlin.org> and Steven Bosscher 4 <stevenb@suse.de> 5 6 This file is part of GCC. 7 8 GCC is free software; you can redistribute it and/or modify 9 it under the terms of the GNU General Public License as published by 10 the Free Software Foundation; either version 3, or (at your option) 11 any later version. 12 13 GCC is distributed in the hope that it will be useful, 14 but WITHOUT ANY WARRANTY; without even the implied warranty of 15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 16 GNU General Public License for more details. 17 18 You should have received a copy of the GNU General Public License 19 along with GCC; see the file COPYING3. If not see 20 <http://www.gnu.org/licenses/>. */ 21 22 #include "config.h" 23 #include "system.h" 24 #include "coretypes.h" 25 #include "backend.h" 26 #include "rtl.h" 27 #include "tree.h" 28 #include "gimple.h" 29 #include "predict.h" 30 #include "alloc-pool.h" 31 #include "tree-pass.h" 32 #include "ssa.h" 33 #include "cgraph.h" 34 #include "gimple-pretty-print.h" 35 #include "fold-const.h" 36 #include "cfganal.h" 37 #include "gimple-fold.h" 38 #include "tree-eh.h" 39 #include "gimplify.h" 40 #include "gimple-iterator.h" 41 #include "tree-cfg.h" 42 #include "tree-ssa-loop.h" 43 #include "tree-into-ssa.h" 44 #include "tree-dfa.h" 45 #include "tree-ssa.h" 46 #include "cfgloop.h" 47 #include "tree-ssa-sccvn.h" 48 #include "tree-scalar-evolution.h" 49 #include "params.h" 50 #include "dbgcnt.h" 51 #include "domwalk.h" 52 #include "tree-ssa-propagate.h" 53 #include "ipa-utils.h" 54 #include "tree-cfgcleanup.h" 55 #include "langhooks.h" 56 #include "alias.h" 57 58 /* Even though this file is called tree-ssa-pre.c, we actually 59 implement a bit more than just PRE here. All of them piggy-back 60 on GVN which is implemented in tree-ssa-sccvn.c. 61 62 1. Full Redundancy Elimination (FRE) 63 This is the elimination phase of GVN. 64 65 2. Partial Redundancy Elimination (PRE) 66 This is adds computation of AVAIL_OUT and ANTIC_IN and 67 doing expression insertion to form GVN-PRE. 68 69 3. Code hoisting 70 This optimization uses the ANTIC_IN sets computed for PRE 71 to move expressions further up than PRE would do, to make 72 multiple computations of the same value fully redundant. 73 This pass is explained below (after the explanation of the 74 basic algorithm for PRE). 75 */ 76 77 /* TODO: 78 79 1. Avail sets can be shared by making an avail_find_leader that 80 walks up the dominator tree and looks in those avail sets. 81 This might affect code optimality, it's unclear right now. 82 Currently the AVAIL_OUT sets are the remaining quadraticness in 83 memory of GVN-PRE. 84 2. Strength reduction can be performed by anticipating expressions 85 we can repair later on. 86 3. We can do back-substitution or smarter value numbering to catch 87 commutative expressions split up over multiple statements. 88 */ 89 90 /* For ease of terminology, "expression node" in the below refers to 91 every expression node but GIMPLE_ASSIGN, because GIMPLE_ASSIGNs 92 represent the actual statement containing the expressions we care about, 93 and we cache the value number by putting it in the expression. */ 94 95 /* Basic algorithm for Partial Redundancy Elimination: 96 97 First we walk the statements to generate the AVAIL sets, the 98 EXP_GEN sets, and the tmp_gen sets. EXP_GEN sets represent the 99 generation of values/expressions by a given block. We use them 100 when computing the ANTIC sets. The AVAIL sets consist of 101 SSA_NAME's that represent values, so we know what values are 102 available in what blocks. AVAIL is a forward dataflow problem. In 103 SSA, values are never killed, so we don't need a kill set, or a 104 fixpoint iteration, in order to calculate the AVAIL sets. In 105 traditional parlance, AVAIL sets tell us the downsafety of the 106 expressions/values. 107 108 Next, we generate the ANTIC sets. These sets represent the 109 anticipatable expressions. ANTIC is a backwards dataflow 110 problem. An expression is anticipatable in a given block if it could 111 be generated in that block. This means that if we had to perform 112 an insertion in that block, of the value of that expression, we 113 could. Calculating the ANTIC sets requires phi translation of 114 expressions, because the flow goes backwards through phis. We must 115 iterate to a fixpoint of the ANTIC sets, because we have a kill 116 set. Even in SSA form, values are not live over the entire 117 function, only from their definition point onwards. So we have to 118 remove values from the ANTIC set once we go past the definition 119 point of the leaders that make them up. 120 compute_antic/compute_antic_aux performs this computation. 121 122 Third, we perform insertions to make partially redundant 123 expressions fully redundant. 124 125 An expression is partially redundant (excluding partial 126 anticipation) if: 127 128 1. It is AVAIL in some, but not all, of the predecessors of a 129 given block. 130 2. It is ANTIC in all the predecessors. 131 132 In order to make it fully redundant, we insert the expression into 133 the predecessors where it is not available, but is ANTIC. 134 135 When optimizing for size, we only eliminate the partial redundancy 136 if we need to insert in only one predecessor. This avoids almost 137 completely the code size increase that PRE usually causes. 138 139 For the partial anticipation case, we only perform insertion if it 140 is partially anticipated in some block, and fully available in all 141 of the predecessors. 142 143 do_pre_regular_insertion/do_pre_partial_partial_insertion 144 performs these steps, driven by insert/insert_aux. 145 146 Fourth, we eliminate fully redundant expressions. 147 This is a simple statement walk that replaces redundant 148 calculations with the now available values. */ 149 150 /* Basic algorithm for Code Hoisting: 151 152 Code hoisting is: Moving value computations up in the control flow 153 graph to make multiple copies redundant. Typically this is a size 154 optimization, but there are cases where it also is helpful for speed. 155 156 A simple code hoisting algorithm is implemented that piggy-backs on 157 the PRE infrastructure. For code hoisting, we have to know ANTIC_OUT 158 which is effectively ANTIC_IN - AVAIL_OUT. The latter two have to be 159 computed for PRE, and we can use them to perform a limited version of 160 code hoisting, too. 161 162 For the purpose of this implementation, a value is hoistable to a basic 163 block B if the following properties are met: 164 165 1. The value is in ANTIC_IN(B) -- the value will be computed on all 166 paths from B to function exit and it can be computed in B); 167 168 2. The value is not in AVAIL_OUT(B) -- there would be no need to 169 compute the value again and make it available twice; 170 171 3. All successors of B are dominated by B -- makes sure that inserting 172 a computation of the value in B will make the remaining 173 computations fully redundant; 174 175 4. At least one successor has the value in AVAIL_OUT -- to avoid 176 hoisting values up too far; 177 178 5. There are at least two successors of B -- hoisting in straight 179 line code is pointless. 180 181 The third condition is not strictly necessary, but it would complicate 182 the hoisting pass a lot. In fact, I don't know of any code hoisting 183 algorithm that does not have this requirement. Fortunately, experiments 184 have show that most candidate hoistable values are in regions that meet 185 this condition (e.g. diamond-shape regions). 186 187 The forth condition is necessary to avoid hoisting things up too far 188 away from the uses of the value. Nothing else limits the algorithm 189 from hoisting everything up as far as ANTIC_IN allows. Experiments 190 with SPEC and CSiBE have shown that hoisting up too far results in more 191 spilling, less benefits for code size, and worse benchmark scores. 192 Fortunately, in practice most of the interesting hoisting opportunities 193 are caught despite this limitation. 194 195 For hoistable values that meet all conditions, expressions are inserted 196 to make the calculation of the hoistable value fully redundant. We 197 perform code hoisting insertions after each round of PRE insertions, 198 because code hoisting never exposes new PRE opportunities, but PRE can 199 create new code hoisting opportunities. 200 201 The code hoisting algorithm is implemented in do_hoist_insert, driven 202 by insert/insert_aux. */ 203 204 /* Representations of value numbers: 205 206 Value numbers are represented by a representative SSA_NAME. We 207 will create fake SSA_NAME's in situations where we need a 208 representative but do not have one (because it is a complex 209 expression). In order to facilitate storing the value numbers in 210 bitmaps, and keep the number of wasted SSA_NAME's down, we also 211 associate a value_id with each value number, and create full blown 212 ssa_name's only where we actually need them (IE in operands of 213 existing expressions). 214 215 Theoretically you could replace all the value_id's with 216 SSA_NAME_VERSION, but this would allocate a large number of 217 SSA_NAME's (which are each > 30 bytes) just to get a 4 byte number. 218 It would also require an additional indirection at each point we 219 use the value id. */ 220 221 /* Representation of expressions on value numbers: 222 223 Expressions consisting of value numbers are represented the same 224 way as our VN internally represents them, with an additional 225 "pre_expr" wrapping around them in order to facilitate storing all 226 of the expressions in the same sets. */ 227 228 /* Representation of sets: 229 230 The dataflow sets do not need to be sorted in any particular order 231 for the majority of their lifetime, are simply represented as two 232 bitmaps, one that keeps track of values present in the set, and one 233 that keeps track of expressions present in the set. 234 235 When we need them in topological order, we produce it on demand by 236 transforming the bitmap into an array and sorting it into topo 237 order. */ 238 239 /* Type of expression, used to know which member of the PRE_EXPR union 240 is valid. */ 241 242 enum pre_expr_kind 243 { 244 NAME, 245 NARY, 246 REFERENCE, 247 CONSTANT 248 }; 249 250 union pre_expr_union 251 { 252 tree name; 253 tree constant; 254 vn_nary_op_t nary; 255 vn_reference_t reference; 256 }; 257 258 typedef struct pre_expr_d : nofree_ptr_hash <pre_expr_d> 259 { 260 enum pre_expr_kind kind; 261 unsigned int id; 262 pre_expr_union u; 263 264 /* hash_table support. */ 265 static inline hashval_t hash (const pre_expr_d *); 266 static inline int equal (const pre_expr_d *, const pre_expr_d *); 267 } *pre_expr; 268 269 #define PRE_EXPR_NAME(e) (e)->u.name 270 #define PRE_EXPR_NARY(e) (e)->u.nary 271 #define PRE_EXPR_REFERENCE(e) (e)->u.reference 272 #define PRE_EXPR_CONSTANT(e) (e)->u.constant 273 274 /* Compare E1 and E1 for equality. */ 275 276 inline int 277 pre_expr_d::equal (const pre_expr_d *e1, const pre_expr_d *e2) 278 { 279 if (e1->kind != e2->kind) 280 return false; 281 282 switch (e1->kind) 283 { 284 case CONSTANT: 285 return vn_constant_eq_with_type (PRE_EXPR_CONSTANT (e1), 286 PRE_EXPR_CONSTANT (e2)); 287 case NAME: 288 return PRE_EXPR_NAME (e1) == PRE_EXPR_NAME (e2); 289 case NARY: 290 return vn_nary_op_eq (PRE_EXPR_NARY (e1), PRE_EXPR_NARY (e2)); 291 case REFERENCE: 292 return vn_reference_eq (PRE_EXPR_REFERENCE (e1), 293 PRE_EXPR_REFERENCE (e2)); 294 default: 295 gcc_unreachable (); 296 } 297 } 298 299 /* Hash E. */ 300 301 inline hashval_t 302 pre_expr_d::hash (const pre_expr_d *e) 303 { 304 switch (e->kind) 305 { 306 case CONSTANT: 307 return vn_hash_constant_with_type (PRE_EXPR_CONSTANT (e)); 308 case NAME: 309 return SSA_NAME_VERSION (PRE_EXPR_NAME (e)); 310 case NARY: 311 return PRE_EXPR_NARY (e)->hashcode; 312 case REFERENCE: 313 return PRE_EXPR_REFERENCE (e)->hashcode; 314 default: 315 gcc_unreachable (); 316 } 317 } 318 319 /* Next global expression id number. */ 320 static unsigned int next_expression_id; 321 322 /* Mapping from expression to id number we can use in bitmap sets. */ 323 static vec<pre_expr> expressions; 324 static hash_table<pre_expr_d> *expression_to_id; 325 static vec<unsigned> name_to_id; 326 327 /* Allocate an expression id for EXPR. */ 328 329 static inline unsigned int 330 alloc_expression_id (pre_expr expr) 331 { 332 struct pre_expr_d **slot; 333 /* Make sure we won't overflow. */ 334 gcc_assert (next_expression_id + 1 > next_expression_id); 335 expr->id = next_expression_id++; 336 expressions.safe_push (expr); 337 if (expr->kind == NAME) 338 { 339 unsigned version = SSA_NAME_VERSION (PRE_EXPR_NAME (expr)); 340 /* vec::safe_grow_cleared allocates no headroom. Avoid frequent 341 re-allocations by using vec::reserve upfront. */ 342 unsigned old_len = name_to_id.length (); 343 name_to_id.reserve (num_ssa_names - old_len); 344 name_to_id.quick_grow_cleared (num_ssa_names); 345 gcc_assert (name_to_id[version] == 0); 346 name_to_id[version] = expr->id; 347 } 348 else 349 { 350 slot = expression_to_id->find_slot (expr, INSERT); 351 gcc_assert (!*slot); 352 *slot = expr; 353 } 354 return next_expression_id - 1; 355 } 356 357 /* Return the expression id for tree EXPR. */ 358 359 static inline unsigned int 360 get_expression_id (const pre_expr expr) 361 { 362 return expr->id; 363 } 364 365 static inline unsigned int 366 lookup_expression_id (const pre_expr expr) 367 { 368 struct pre_expr_d **slot; 369 370 if (expr->kind == NAME) 371 { 372 unsigned version = SSA_NAME_VERSION (PRE_EXPR_NAME (expr)); 373 if (name_to_id.length () <= version) 374 return 0; 375 return name_to_id[version]; 376 } 377 else 378 { 379 slot = expression_to_id->find_slot (expr, NO_INSERT); 380 if (!slot) 381 return 0; 382 return ((pre_expr)*slot)->id; 383 } 384 } 385 386 /* Return the existing expression id for EXPR, or create one if one 387 does not exist yet. */ 388 389 static inline unsigned int 390 get_or_alloc_expression_id (pre_expr expr) 391 { 392 unsigned int id = lookup_expression_id (expr); 393 if (id == 0) 394 return alloc_expression_id (expr); 395 return expr->id = id; 396 } 397 398 /* Return the expression that has expression id ID */ 399 400 static inline pre_expr 401 expression_for_id (unsigned int id) 402 { 403 return expressions[id]; 404 } 405 406 /* Free the expression id field in all of our expressions, 407 and then destroy the expressions array. */ 408 409 static void 410 clear_expression_ids (void) 411 { 412 expressions.release (); 413 } 414 415 static object_allocator<pre_expr_d> pre_expr_pool ("pre_expr nodes"); 416 417 /* Given an SSA_NAME NAME, get or create a pre_expr to represent it. */ 418 419 static pre_expr 420 get_or_alloc_expr_for_name (tree name) 421 { 422 struct pre_expr_d expr; 423 pre_expr result; 424 unsigned int result_id; 425 426 expr.kind = NAME; 427 expr.id = 0; 428 PRE_EXPR_NAME (&expr) = name; 429 result_id = lookup_expression_id (&expr); 430 if (result_id != 0) 431 return expression_for_id (result_id); 432 433 result = pre_expr_pool.allocate (); 434 result->kind = NAME; 435 PRE_EXPR_NAME (result) = name; 436 alloc_expression_id (result); 437 return result; 438 } 439 440 /* An unordered bitmap set. One bitmap tracks values, the other, 441 expressions. */ 442 typedef struct bitmap_set 443 { 444 bitmap_head expressions; 445 bitmap_head values; 446 } *bitmap_set_t; 447 448 #define FOR_EACH_EXPR_ID_IN_SET(set, id, bi) \ 449 EXECUTE_IF_SET_IN_BITMAP (&(set)->expressions, 0, (id), (bi)) 450 451 #define FOR_EACH_VALUE_ID_IN_SET(set, id, bi) \ 452 EXECUTE_IF_SET_IN_BITMAP (&(set)->values, 0, (id), (bi)) 453 454 /* Mapping from value id to expressions with that value_id. */ 455 static vec<bitmap> value_expressions; 456 457 /* Sets that we need to keep track of. */ 458 typedef struct bb_bitmap_sets 459 { 460 /* The EXP_GEN set, which represents expressions/values generated in 461 a basic block. */ 462 bitmap_set_t exp_gen; 463 464 /* The PHI_GEN set, which represents PHI results generated in a 465 basic block. */ 466 bitmap_set_t phi_gen; 467 468 /* The TMP_GEN set, which represents results/temporaries generated 469 in a basic block. IE the LHS of an expression. */ 470 bitmap_set_t tmp_gen; 471 472 /* The AVAIL_OUT set, which represents which values are available in 473 a given basic block. */ 474 bitmap_set_t avail_out; 475 476 /* The ANTIC_IN set, which represents which values are anticipatable 477 in a given basic block. */ 478 bitmap_set_t antic_in; 479 480 /* The PA_IN set, which represents which values are 481 partially anticipatable in a given basic block. */ 482 bitmap_set_t pa_in; 483 484 /* The NEW_SETS set, which is used during insertion to augment the 485 AVAIL_OUT set of blocks with the new insertions performed during 486 the current iteration. */ 487 bitmap_set_t new_sets; 488 489 /* A cache for value_dies_in_block_x. */ 490 bitmap expr_dies; 491 492 /* The live virtual operand on successor edges. */ 493 tree vop_on_exit; 494 495 /* True if we have visited this block during ANTIC calculation. */ 496 unsigned int visited : 1; 497 498 /* True when the block contains a call that might not return. */ 499 unsigned int contains_may_not_return_call : 1; 500 } *bb_value_sets_t; 501 502 #define EXP_GEN(BB) ((bb_value_sets_t) ((BB)->aux))->exp_gen 503 #define PHI_GEN(BB) ((bb_value_sets_t) ((BB)->aux))->phi_gen 504 #define TMP_GEN(BB) ((bb_value_sets_t) ((BB)->aux))->tmp_gen 505 #define AVAIL_OUT(BB) ((bb_value_sets_t) ((BB)->aux))->avail_out 506 #define ANTIC_IN(BB) ((bb_value_sets_t) ((BB)->aux))->antic_in 507 #define PA_IN(BB) ((bb_value_sets_t) ((BB)->aux))->pa_in 508 #define NEW_SETS(BB) ((bb_value_sets_t) ((BB)->aux))->new_sets 509 #define EXPR_DIES(BB) ((bb_value_sets_t) ((BB)->aux))->expr_dies 510 #define BB_VISITED(BB) ((bb_value_sets_t) ((BB)->aux))->visited 511 #define BB_MAY_NOTRETURN(BB) ((bb_value_sets_t) ((BB)->aux))->contains_may_not_return_call 512 #define BB_LIVE_VOP_ON_EXIT(BB) ((bb_value_sets_t) ((BB)->aux))->vop_on_exit 513 514 515 /* This structure is used to keep track of statistics on what 516 optimization PRE was able to perform. */ 517 static struct 518 { 519 /* The number of RHS computations eliminated by PRE. */ 520 int eliminations; 521 522 /* The number of new expressions/temporaries generated by PRE. */ 523 int insertions; 524 525 /* The number of inserts found due to partial anticipation */ 526 int pa_insert; 527 528 /* The number of inserts made for code hoisting. */ 529 int hoist_insert; 530 531 /* The number of new PHI nodes added by PRE. */ 532 int phis; 533 } pre_stats; 534 535 static bool do_partial_partial; 536 static pre_expr bitmap_find_leader (bitmap_set_t, unsigned int); 537 static void bitmap_value_insert_into_set (bitmap_set_t, pre_expr); 538 static void bitmap_value_replace_in_set (bitmap_set_t, pre_expr); 539 static void bitmap_set_copy (bitmap_set_t, bitmap_set_t); 540 static void bitmap_set_and (bitmap_set_t, bitmap_set_t); 541 static bool bitmap_set_contains_value (bitmap_set_t, unsigned int); 542 static void bitmap_insert_into_set (bitmap_set_t, pre_expr); 543 static void bitmap_insert_into_set_1 (bitmap_set_t, pre_expr, 544 unsigned int, bool); 545 static bitmap_set_t bitmap_set_new (void); 546 static tree create_expression_by_pieces (basic_block, pre_expr, gimple_seq *, 547 tree); 548 static tree find_or_generate_expression (basic_block, tree, gimple_seq *); 549 static unsigned int get_expr_value_id (pre_expr); 550 551 /* We can add and remove elements and entries to and from sets 552 and hash tables, so we use alloc pools for them. */ 553 554 static object_allocator<bitmap_set> bitmap_set_pool ("Bitmap sets"); 555 static bitmap_obstack grand_bitmap_obstack; 556 557 /* Set of blocks with statements that have had their EH properties changed. */ 558 static bitmap need_eh_cleanup; 559 560 /* Set of blocks with statements that have had their AB properties changed. */ 561 static bitmap need_ab_cleanup; 562 563 /* A three tuple {e, pred, v} used to cache phi translations in the 564 phi_translate_table. */ 565 566 typedef struct expr_pred_trans_d : free_ptr_hash<expr_pred_trans_d> 567 { 568 /* The expression. */ 569 pre_expr e; 570 571 /* The predecessor block along which we translated the expression. */ 572 basic_block pred; 573 574 /* The value that resulted from the translation. */ 575 pre_expr v; 576 577 /* The hashcode for the expression, pred pair. This is cached for 578 speed reasons. */ 579 hashval_t hashcode; 580 581 /* hash_table support. */ 582 static inline hashval_t hash (const expr_pred_trans_d *); 583 static inline int equal (const expr_pred_trans_d *, const expr_pred_trans_d *); 584 } *expr_pred_trans_t; 585 typedef const struct expr_pred_trans_d *const_expr_pred_trans_t; 586 587 inline hashval_t 588 expr_pred_trans_d::hash (const expr_pred_trans_d *e) 589 { 590 return e->hashcode; 591 } 592 593 inline int 594 expr_pred_trans_d::equal (const expr_pred_trans_d *ve1, 595 const expr_pred_trans_d *ve2) 596 { 597 basic_block b1 = ve1->pred; 598 basic_block b2 = ve2->pred; 599 600 /* If they are not translations for the same basic block, they can't 601 be equal. */ 602 if (b1 != b2) 603 return false; 604 return pre_expr_d::equal (ve1->e, ve2->e); 605 } 606 607 /* The phi_translate_table caches phi translations for a given 608 expression and predecessor. */ 609 static hash_table<expr_pred_trans_d> *phi_translate_table; 610 611 /* Add the tuple mapping from {expression E, basic block PRED} to 612 the phi translation table and return whether it pre-existed. */ 613 614 static inline bool 615 phi_trans_add (expr_pred_trans_t *entry, pre_expr e, basic_block pred) 616 { 617 expr_pred_trans_t *slot; 618 expr_pred_trans_d tem; 619 hashval_t hash = iterative_hash_hashval_t (pre_expr_d::hash (e), 620 pred->index); 621 tem.e = e; 622 tem.pred = pred; 623 tem.hashcode = hash; 624 slot = phi_translate_table->find_slot_with_hash (&tem, hash, INSERT); 625 if (*slot) 626 { 627 *entry = *slot; 628 return true; 629 } 630 631 *entry = *slot = XNEW (struct expr_pred_trans_d); 632 (*entry)->e = e; 633 (*entry)->pred = pred; 634 (*entry)->hashcode = hash; 635 return false; 636 } 637 638 639 /* Add expression E to the expression set of value id V. */ 640 641 static void 642 add_to_value (unsigned int v, pre_expr e) 643 { 644 bitmap set; 645 646 gcc_checking_assert (get_expr_value_id (e) == v); 647 648 if (v >= value_expressions.length ()) 649 { 650 value_expressions.safe_grow_cleared (v + 1); 651 } 652 653 set = value_expressions[v]; 654 if (!set) 655 { 656 set = BITMAP_ALLOC (&grand_bitmap_obstack); 657 value_expressions[v] = set; 658 } 659 660 bitmap_set_bit (set, get_or_alloc_expression_id (e)); 661 } 662 663 /* Create a new bitmap set and return it. */ 664 665 static bitmap_set_t 666 bitmap_set_new (void) 667 { 668 bitmap_set_t ret = bitmap_set_pool.allocate (); 669 bitmap_initialize (&ret->expressions, &grand_bitmap_obstack); 670 bitmap_initialize (&ret->values, &grand_bitmap_obstack); 671 return ret; 672 } 673 674 /* Return the value id for a PRE expression EXPR. */ 675 676 static unsigned int 677 get_expr_value_id (pre_expr expr) 678 { 679 unsigned int id; 680 switch (expr->kind) 681 { 682 case CONSTANT: 683 id = get_constant_value_id (PRE_EXPR_CONSTANT (expr)); 684 break; 685 case NAME: 686 id = VN_INFO (PRE_EXPR_NAME (expr))->value_id; 687 break; 688 case NARY: 689 id = PRE_EXPR_NARY (expr)->value_id; 690 break; 691 case REFERENCE: 692 id = PRE_EXPR_REFERENCE (expr)->value_id; 693 break; 694 default: 695 gcc_unreachable (); 696 } 697 /* ??? We cannot assert that expr has a value-id (it can be 0), because 698 we assign value-ids only to expressions that have a result 699 in set_hashtable_value_ids. */ 700 return id; 701 } 702 703 /* Return a SCCVN valnum (SSA name or constant) for the PRE value-id VAL. */ 704 705 static tree 706 sccvn_valnum_from_value_id (unsigned int val) 707 { 708 bitmap_iterator bi; 709 unsigned int i; 710 bitmap exprset = value_expressions[val]; 711 EXECUTE_IF_SET_IN_BITMAP (exprset, 0, i, bi) 712 { 713 pre_expr vexpr = expression_for_id (i); 714 if (vexpr->kind == NAME) 715 return VN_INFO (PRE_EXPR_NAME (vexpr))->valnum; 716 else if (vexpr->kind == CONSTANT) 717 return PRE_EXPR_CONSTANT (vexpr); 718 } 719 return NULL_TREE; 720 } 721 722 /* Remove an expression EXPR from a bitmapped set. */ 723 724 static void 725 bitmap_remove_from_set (bitmap_set_t set, pre_expr expr) 726 { 727 unsigned int val = get_expr_value_id (expr); 728 if (!value_id_constant_p (val)) 729 { 730 bitmap_clear_bit (&set->values, val); 731 bitmap_clear_bit (&set->expressions, get_expression_id (expr)); 732 } 733 } 734 735 static void 736 bitmap_insert_into_set_1 (bitmap_set_t set, pre_expr expr, 737 unsigned int val, bool allow_constants) 738 { 739 if (allow_constants || !value_id_constant_p (val)) 740 { 741 /* We specifically expect this and only this function to be able to 742 insert constants into a set. */ 743 bitmap_set_bit (&set->values, val); 744 bitmap_set_bit (&set->expressions, get_or_alloc_expression_id (expr)); 745 } 746 } 747 748 /* Insert an expression EXPR into a bitmapped set. */ 749 750 static void 751 bitmap_insert_into_set (bitmap_set_t set, pre_expr expr) 752 { 753 bitmap_insert_into_set_1 (set, expr, get_expr_value_id (expr), false); 754 } 755 756 /* Copy a bitmapped set ORIG, into bitmapped set DEST. */ 757 758 static void 759 bitmap_set_copy (bitmap_set_t dest, bitmap_set_t orig) 760 { 761 bitmap_copy (&dest->expressions, &orig->expressions); 762 bitmap_copy (&dest->values, &orig->values); 763 } 764 765 766 /* Free memory used up by SET. */ 767 static void 768 bitmap_set_free (bitmap_set_t set) 769 { 770 bitmap_clear (&set->expressions); 771 bitmap_clear (&set->values); 772 } 773 774 775 /* Generate an topological-ordered array of bitmap set SET. */ 776 777 static vec<pre_expr> 778 sorted_array_from_bitmap_set (bitmap_set_t set) 779 { 780 unsigned int i, j; 781 bitmap_iterator bi, bj; 782 vec<pre_expr> result; 783 784 /* Pre-allocate enough space for the array. */ 785 result.create (bitmap_count_bits (&set->expressions)); 786 787 FOR_EACH_VALUE_ID_IN_SET (set, i, bi) 788 { 789 /* The number of expressions having a given value is usually 790 relatively small. Thus, rather than making a vector of all 791 the expressions and sorting it by value-id, we walk the values 792 and check in the reverse mapping that tells us what expressions 793 have a given value, to filter those in our set. As a result, 794 the expressions are inserted in value-id order, which means 795 topological order. 796 797 If this is somehow a significant lose for some cases, we can 798 choose which set to walk based on the set size. */ 799 bitmap exprset = value_expressions[i]; 800 EXECUTE_IF_SET_IN_BITMAP (exprset, 0, j, bj) 801 { 802 if (bitmap_bit_p (&set->expressions, j)) 803 result.quick_push (expression_for_id (j)); 804 } 805 } 806 807 return result; 808 } 809 810 /* Perform bitmapped set operation DEST &= ORIG. */ 811 812 static void 813 bitmap_set_and (bitmap_set_t dest, bitmap_set_t orig) 814 { 815 bitmap_iterator bi; 816 unsigned int i; 817 818 if (dest != orig) 819 { 820 bitmap_head temp; 821 bitmap_initialize (&temp, &grand_bitmap_obstack); 822 823 bitmap_and_into (&dest->values, &orig->values); 824 bitmap_copy (&temp, &dest->expressions); 825 EXECUTE_IF_SET_IN_BITMAP (&temp, 0, i, bi) 826 { 827 pre_expr expr = expression_for_id (i); 828 unsigned int value_id = get_expr_value_id (expr); 829 if (!bitmap_bit_p (&dest->values, value_id)) 830 bitmap_clear_bit (&dest->expressions, i); 831 } 832 bitmap_clear (&temp); 833 } 834 } 835 836 /* Subtract all values and expressions contained in ORIG from DEST. */ 837 838 static bitmap_set_t 839 bitmap_set_subtract (bitmap_set_t dest, bitmap_set_t orig) 840 { 841 bitmap_set_t result = bitmap_set_new (); 842 bitmap_iterator bi; 843 unsigned int i; 844 845 bitmap_and_compl (&result->expressions, &dest->expressions, 846 &orig->expressions); 847 848 FOR_EACH_EXPR_ID_IN_SET (result, i, bi) 849 { 850 pre_expr expr = expression_for_id (i); 851 unsigned int value_id = get_expr_value_id (expr); 852 bitmap_set_bit (&result->values, value_id); 853 } 854 855 return result; 856 } 857 858 /* Subtract all the values in bitmap set B from bitmap set A. */ 859 860 static void 861 bitmap_set_subtract_values (bitmap_set_t a, bitmap_set_t b) 862 { 863 unsigned int i; 864 bitmap_iterator bi; 865 bitmap_head temp; 866 867 bitmap_initialize (&temp, &grand_bitmap_obstack); 868 869 bitmap_copy (&temp, &a->expressions); 870 EXECUTE_IF_SET_IN_BITMAP (&temp, 0, i, bi) 871 { 872 pre_expr expr = expression_for_id (i); 873 if (bitmap_set_contains_value (b, get_expr_value_id (expr))) 874 bitmap_remove_from_set (a, expr); 875 } 876 bitmap_clear (&temp); 877 } 878 879 880 /* Return true if bitmapped set SET contains the value VALUE_ID. */ 881 882 static bool 883 bitmap_set_contains_value (bitmap_set_t set, unsigned int value_id) 884 { 885 if (value_id_constant_p (value_id)) 886 return true; 887 888 if (!set || bitmap_empty_p (&set->expressions)) 889 return false; 890 891 return bitmap_bit_p (&set->values, value_id); 892 } 893 894 static inline bool 895 bitmap_set_contains_expr (bitmap_set_t set, const pre_expr expr) 896 { 897 return bitmap_bit_p (&set->expressions, get_expression_id (expr)); 898 } 899 900 /* Replace an instance of value LOOKFOR with expression EXPR in SET. */ 901 902 static void 903 bitmap_set_replace_value (bitmap_set_t set, unsigned int lookfor, 904 const pre_expr expr) 905 { 906 bitmap exprset; 907 unsigned int i; 908 bitmap_iterator bi; 909 910 if (value_id_constant_p (lookfor)) 911 return; 912 913 if (!bitmap_set_contains_value (set, lookfor)) 914 return; 915 916 /* The number of expressions having a given value is usually 917 significantly less than the total number of expressions in SET. 918 Thus, rather than check, for each expression in SET, whether it 919 has the value LOOKFOR, we walk the reverse mapping that tells us 920 what expressions have a given value, and see if any of those 921 expressions are in our set. For large testcases, this is about 922 5-10x faster than walking the bitmap. If this is somehow a 923 significant lose for some cases, we can choose which set to walk 924 based on the set size. */ 925 exprset = value_expressions[lookfor]; 926 EXECUTE_IF_SET_IN_BITMAP (exprset, 0, i, bi) 927 { 928 if (bitmap_clear_bit (&set->expressions, i)) 929 { 930 bitmap_set_bit (&set->expressions, get_expression_id (expr)); 931 return; 932 } 933 } 934 935 gcc_unreachable (); 936 } 937 938 /* Return true if two bitmap sets are equal. */ 939 940 static bool 941 bitmap_set_equal (bitmap_set_t a, bitmap_set_t b) 942 { 943 return bitmap_equal_p (&a->values, &b->values); 944 } 945 946 /* Replace an instance of EXPR's VALUE with EXPR in SET if it exists, 947 and add it otherwise. */ 948 949 static void 950 bitmap_value_replace_in_set (bitmap_set_t set, pre_expr expr) 951 { 952 unsigned int val = get_expr_value_id (expr); 953 954 if (bitmap_set_contains_value (set, val)) 955 bitmap_set_replace_value (set, val, expr); 956 else 957 bitmap_insert_into_set (set, expr); 958 } 959 960 /* Insert EXPR into SET if EXPR's value is not already present in 961 SET. */ 962 963 static void 964 bitmap_value_insert_into_set (bitmap_set_t set, pre_expr expr) 965 { 966 unsigned int val = get_expr_value_id (expr); 967 968 gcc_checking_assert (expr->id == get_or_alloc_expression_id (expr)); 969 970 /* Constant values are always considered to be part of the set. */ 971 if (value_id_constant_p (val)) 972 return; 973 974 /* If the value membership changed, add the expression. */ 975 if (bitmap_set_bit (&set->values, val)) 976 bitmap_set_bit (&set->expressions, expr->id); 977 } 978 979 /* Print out EXPR to outfile. */ 980 981 static void 982 print_pre_expr (FILE *outfile, const pre_expr expr) 983 { 984 switch (expr->kind) 985 { 986 case CONSTANT: 987 print_generic_expr (outfile, PRE_EXPR_CONSTANT (expr), 0); 988 break; 989 case NAME: 990 print_generic_expr (outfile, PRE_EXPR_NAME (expr), 0); 991 break; 992 case NARY: 993 { 994 unsigned int i; 995 vn_nary_op_t nary = PRE_EXPR_NARY (expr); 996 fprintf (outfile, "{%s,", get_tree_code_name (nary->opcode)); 997 for (i = 0; i < nary->length; i++) 998 { 999 print_generic_expr (outfile, nary->op[i], 0); 1000 if (i != (unsigned) nary->length - 1) 1001 fprintf (outfile, ","); 1002 } 1003 fprintf (outfile, "}"); 1004 } 1005 break; 1006 1007 case REFERENCE: 1008 { 1009 vn_reference_op_t vro; 1010 unsigned int i; 1011 vn_reference_t ref = PRE_EXPR_REFERENCE (expr); 1012 fprintf (outfile, "{"); 1013 for (i = 0; 1014 ref->operands.iterate (i, &vro); 1015 i++) 1016 { 1017 bool closebrace = false; 1018 if (vro->opcode != SSA_NAME 1019 && TREE_CODE_CLASS (vro->opcode) != tcc_declaration) 1020 { 1021 fprintf (outfile, "%s", get_tree_code_name (vro->opcode)); 1022 if (vro->op0) 1023 { 1024 fprintf (outfile, "<"); 1025 closebrace = true; 1026 } 1027 } 1028 if (vro->op0) 1029 { 1030 print_generic_expr (outfile, vro->op0, 0); 1031 if (vro->op1) 1032 { 1033 fprintf (outfile, ","); 1034 print_generic_expr (outfile, vro->op1, 0); 1035 } 1036 if (vro->op2) 1037 { 1038 fprintf (outfile, ","); 1039 print_generic_expr (outfile, vro->op2, 0); 1040 } 1041 } 1042 if (closebrace) 1043 fprintf (outfile, ">"); 1044 if (i != ref->operands.length () - 1) 1045 fprintf (outfile, ","); 1046 } 1047 fprintf (outfile, "}"); 1048 if (ref->vuse) 1049 { 1050 fprintf (outfile, "@"); 1051 print_generic_expr (outfile, ref->vuse, 0); 1052 } 1053 } 1054 break; 1055 } 1056 } 1057 void debug_pre_expr (pre_expr); 1058 1059 /* Like print_pre_expr but always prints to stderr. */ 1060 DEBUG_FUNCTION void 1061 debug_pre_expr (pre_expr e) 1062 { 1063 print_pre_expr (stderr, e); 1064 fprintf (stderr, "\n"); 1065 } 1066 1067 /* Print out SET to OUTFILE. */ 1068 1069 static void 1070 print_bitmap_set (FILE *outfile, bitmap_set_t set, 1071 const char *setname, int blockindex) 1072 { 1073 fprintf (outfile, "%s[%d] := { ", setname, blockindex); 1074 if (set) 1075 { 1076 bool first = true; 1077 unsigned i; 1078 bitmap_iterator bi; 1079 1080 FOR_EACH_EXPR_ID_IN_SET (set, i, bi) 1081 { 1082 const pre_expr expr = expression_for_id (i); 1083 1084 if (!first) 1085 fprintf (outfile, ", "); 1086 first = false; 1087 print_pre_expr (outfile, expr); 1088 1089 fprintf (outfile, " (%04d)", get_expr_value_id (expr)); 1090 } 1091 } 1092 fprintf (outfile, " }\n"); 1093 } 1094 1095 void debug_bitmap_set (bitmap_set_t); 1096 1097 DEBUG_FUNCTION void 1098 debug_bitmap_set (bitmap_set_t set) 1099 { 1100 print_bitmap_set (stderr, set, "debug", 0); 1101 } 1102 1103 void debug_bitmap_sets_for (basic_block); 1104 1105 DEBUG_FUNCTION void 1106 debug_bitmap_sets_for (basic_block bb) 1107 { 1108 print_bitmap_set (stderr, AVAIL_OUT (bb), "avail_out", bb->index); 1109 print_bitmap_set (stderr, EXP_GEN (bb), "exp_gen", bb->index); 1110 print_bitmap_set (stderr, PHI_GEN (bb), "phi_gen", bb->index); 1111 print_bitmap_set (stderr, TMP_GEN (bb), "tmp_gen", bb->index); 1112 print_bitmap_set (stderr, ANTIC_IN (bb), "antic_in", bb->index); 1113 if (do_partial_partial) 1114 print_bitmap_set (stderr, PA_IN (bb), "pa_in", bb->index); 1115 print_bitmap_set (stderr, NEW_SETS (bb), "new_sets", bb->index); 1116 } 1117 1118 /* Print out the expressions that have VAL to OUTFILE. */ 1119 1120 static void 1121 print_value_expressions (FILE *outfile, unsigned int val) 1122 { 1123 bitmap set = value_expressions[val]; 1124 if (set) 1125 { 1126 bitmap_set x; 1127 char s[10]; 1128 sprintf (s, "%04d", val); 1129 x.expressions = *set; 1130 print_bitmap_set (outfile, &x, s, 0); 1131 } 1132 } 1133 1134 1135 DEBUG_FUNCTION void 1136 debug_value_expressions (unsigned int val) 1137 { 1138 print_value_expressions (stderr, val); 1139 } 1140 1141 /* Given a CONSTANT, allocate a new CONSTANT type PRE_EXPR to 1142 represent it. */ 1143 1144 static pre_expr 1145 get_or_alloc_expr_for_constant (tree constant) 1146 { 1147 unsigned int result_id; 1148 unsigned int value_id; 1149 struct pre_expr_d expr; 1150 pre_expr newexpr; 1151 1152 expr.kind = CONSTANT; 1153 PRE_EXPR_CONSTANT (&expr) = constant; 1154 result_id = lookup_expression_id (&expr); 1155 if (result_id != 0) 1156 return expression_for_id (result_id); 1157 1158 newexpr = pre_expr_pool.allocate (); 1159 newexpr->kind = CONSTANT; 1160 PRE_EXPR_CONSTANT (newexpr) = constant; 1161 alloc_expression_id (newexpr); 1162 value_id = get_or_alloc_constant_value_id (constant); 1163 add_to_value (value_id, newexpr); 1164 return newexpr; 1165 } 1166 1167 /* Get or allocate a pre_expr for a piece of GIMPLE, and return it. 1168 Currently only supports constants and SSA_NAMES. */ 1169 static pre_expr 1170 get_or_alloc_expr_for (tree t) 1171 { 1172 if (TREE_CODE (t) == SSA_NAME) 1173 return get_or_alloc_expr_for_name (t); 1174 else if (is_gimple_min_invariant (t)) 1175 return get_or_alloc_expr_for_constant (t); 1176 else 1177 { 1178 /* More complex expressions can result from SCCVN expression 1179 simplification that inserts values for them. As they all 1180 do not have VOPs the get handled by the nary ops struct. */ 1181 vn_nary_op_t result; 1182 unsigned int result_id; 1183 vn_nary_op_lookup (t, &result); 1184 if (result != NULL) 1185 { 1186 pre_expr e = pre_expr_pool.allocate (); 1187 e->kind = NARY; 1188 PRE_EXPR_NARY (e) = result; 1189 result_id = lookup_expression_id (e); 1190 if (result_id != 0) 1191 { 1192 pre_expr_pool.remove (e); 1193 e = expression_for_id (result_id); 1194 return e; 1195 } 1196 alloc_expression_id (e); 1197 return e; 1198 } 1199 } 1200 return NULL; 1201 } 1202 1203 /* Return the folded version of T if T, when folded, is a gimple 1204 min_invariant or an SSA name. Otherwise, return T. */ 1205 1206 static pre_expr 1207 fully_constant_expression (pre_expr e) 1208 { 1209 switch (e->kind) 1210 { 1211 case CONSTANT: 1212 return e; 1213 case NARY: 1214 { 1215 vn_nary_op_t nary = PRE_EXPR_NARY (e); 1216 tree res = vn_nary_simplify (nary); 1217 if (!res) 1218 return e; 1219 if (is_gimple_min_invariant (res)) 1220 return get_or_alloc_expr_for_constant (res); 1221 if (TREE_CODE (res) == SSA_NAME) 1222 return get_or_alloc_expr_for_name (res); 1223 return e; 1224 } 1225 case REFERENCE: 1226 { 1227 vn_reference_t ref = PRE_EXPR_REFERENCE (e); 1228 tree folded; 1229 if ((folded = fully_constant_vn_reference_p (ref))) 1230 return get_or_alloc_expr_for_constant (folded); 1231 return e; 1232 } 1233 default: 1234 return e; 1235 } 1236 return e; 1237 } 1238 1239 /* Translate the VUSE backwards through phi nodes in PHIBLOCK, so that 1240 it has the value it would have in BLOCK. Set *SAME_VALID to true 1241 in case the new vuse doesn't change the value id of the OPERANDS. */ 1242 1243 static tree 1244 translate_vuse_through_block (vec<vn_reference_op_s> operands, 1245 alias_set_type set, tree type, tree vuse, 1246 basic_block phiblock, 1247 basic_block block, bool *same_valid) 1248 { 1249 gimple *phi = SSA_NAME_DEF_STMT (vuse); 1250 ao_ref ref; 1251 edge e = NULL; 1252 bool use_oracle; 1253 1254 *same_valid = true; 1255 1256 if (gimple_bb (phi) != phiblock) 1257 return vuse; 1258 1259 use_oracle = ao_ref_init_from_vn_reference (&ref, set, type, operands); 1260 1261 /* Use the alias-oracle to find either the PHI node in this block, 1262 the first VUSE used in this block that is equivalent to vuse or 1263 the first VUSE which definition in this block kills the value. */ 1264 if (gimple_code (phi) == GIMPLE_PHI) 1265 e = find_edge (block, phiblock); 1266 else if (use_oracle) 1267 while (!stmt_may_clobber_ref_p_1 (phi, &ref)) 1268 { 1269 vuse = gimple_vuse (phi); 1270 phi = SSA_NAME_DEF_STMT (vuse); 1271 if (gimple_bb (phi) != phiblock) 1272 return vuse; 1273 if (gimple_code (phi) == GIMPLE_PHI) 1274 { 1275 e = find_edge (block, phiblock); 1276 break; 1277 } 1278 } 1279 else 1280 return NULL_TREE; 1281 1282 if (e) 1283 { 1284 if (use_oracle) 1285 { 1286 bitmap visited = NULL; 1287 unsigned int cnt; 1288 /* Try to find a vuse that dominates this phi node by skipping 1289 non-clobbering statements. */ 1290 vuse = get_continuation_for_phi (phi, &ref, &cnt, &visited, false, 1291 NULL, NULL); 1292 if (visited) 1293 BITMAP_FREE (visited); 1294 } 1295 else 1296 vuse = NULL_TREE; 1297 if (!vuse) 1298 { 1299 /* If we didn't find any, the value ID can't stay the same, 1300 but return the translated vuse. */ 1301 *same_valid = false; 1302 vuse = PHI_ARG_DEF (phi, e->dest_idx); 1303 } 1304 /* ??? We would like to return vuse here as this is the canonical 1305 upmost vdef that this reference is associated with. But during 1306 insertion of the references into the hash tables we only ever 1307 directly insert with their direct gimple_vuse, hence returning 1308 something else would make us not find the other expression. */ 1309 return PHI_ARG_DEF (phi, e->dest_idx); 1310 } 1311 1312 return NULL_TREE; 1313 } 1314 1315 /* Like bitmap_find_leader, but checks for the value existing in SET1 *or* 1316 SET2. This is used to avoid making a set consisting of the union 1317 of PA_IN and ANTIC_IN during insert. */ 1318 1319 static inline pre_expr 1320 find_leader_in_sets (unsigned int val, bitmap_set_t set1, bitmap_set_t set2) 1321 { 1322 pre_expr result; 1323 1324 result = bitmap_find_leader (set1, val); 1325 if (!result && set2) 1326 result = bitmap_find_leader (set2, val); 1327 return result; 1328 } 1329 1330 /* Get the tree type for our PRE expression e. */ 1331 1332 static tree 1333 get_expr_type (const pre_expr e) 1334 { 1335 switch (e->kind) 1336 { 1337 case NAME: 1338 return TREE_TYPE (PRE_EXPR_NAME (e)); 1339 case CONSTANT: 1340 return TREE_TYPE (PRE_EXPR_CONSTANT (e)); 1341 case REFERENCE: 1342 return PRE_EXPR_REFERENCE (e)->type; 1343 case NARY: 1344 return PRE_EXPR_NARY (e)->type; 1345 } 1346 gcc_unreachable (); 1347 } 1348 1349 /* Get a representative SSA_NAME for a given expression. 1350 Since all of our sub-expressions are treated as values, we require 1351 them to be SSA_NAME's for simplicity. 1352 Prior versions of GVNPRE used to use "value handles" here, so that 1353 an expression would be VH.11 + VH.10 instead of d_3 + e_6. In 1354 either case, the operands are really values (IE we do not expect 1355 them to be usable without finding leaders). */ 1356 1357 static tree 1358 get_representative_for (const pre_expr e) 1359 { 1360 tree name; 1361 unsigned int value_id = get_expr_value_id (e); 1362 1363 switch (e->kind) 1364 { 1365 case NAME: 1366 return VN_INFO (PRE_EXPR_NAME (e))->valnum; 1367 case CONSTANT: 1368 return PRE_EXPR_CONSTANT (e); 1369 case NARY: 1370 case REFERENCE: 1371 { 1372 /* Go through all of the expressions representing this value 1373 and pick out an SSA_NAME. */ 1374 unsigned int i; 1375 bitmap_iterator bi; 1376 bitmap exprs = value_expressions[value_id]; 1377 EXECUTE_IF_SET_IN_BITMAP (exprs, 0, i, bi) 1378 { 1379 pre_expr rep = expression_for_id (i); 1380 if (rep->kind == NAME) 1381 return VN_INFO (PRE_EXPR_NAME (rep))->valnum; 1382 else if (rep->kind == CONSTANT) 1383 return PRE_EXPR_CONSTANT (rep); 1384 } 1385 } 1386 break; 1387 } 1388 1389 /* If we reached here we couldn't find an SSA_NAME. This can 1390 happen when we've discovered a value that has never appeared in 1391 the program as set to an SSA_NAME, as the result of phi translation. 1392 Create one here. 1393 ??? We should be able to re-use this when we insert the statement 1394 to compute it. */ 1395 name = make_temp_ssa_name (get_expr_type (e), gimple_build_nop (), "pretmp"); 1396 VN_INFO_GET (name)->value_id = value_id; 1397 VN_INFO (name)->valnum = name; 1398 /* ??? For now mark this SSA name for release by SCCVN. */ 1399 VN_INFO (name)->needs_insertion = true; 1400 add_to_value (value_id, get_or_alloc_expr_for_name (name)); 1401 if (dump_file && (dump_flags & TDF_DETAILS)) 1402 { 1403 fprintf (dump_file, "Created SSA_NAME representative "); 1404 print_generic_expr (dump_file, name, 0); 1405 fprintf (dump_file, " for expression:"); 1406 print_pre_expr (dump_file, e); 1407 fprintf (dump_file, " (%04d)\n", value_id); 1408 } 1409 1410 return name; 1411 } 1412 1413 1414 1415 static pre_expr 1416 phi_translate (pre_expr expr, bitmap_set_t set1, bitmap_set_t set2, 1417 basic_block pred, basic_block phiblock); 1418 1419 /* Translate EXPR using phis in PHIBLOCK, so that it has the values of 1420 the phis in PRED. Return NULL if we can't find a leader for each part 1421 of the translated expression. */ 1422 1423 static pre_expr 1424 phi_translate_1 (pre_expr expr, bitmap_set_t set1, bitmap_set_t set2, 1425 basic_block pred, basic_block phiblock) 1426 { 1427 switch (expr->kind) 1428 { 1429 case NARY: 1430 { 1431 unsigned int i; 1432 bool changed = false; 1433 vn_nary_op_t nary = PRE_EXPR_NARY (expr); 1434 vn_nary_op_t newnary = XALLOCAVAR (struct vn_nary_op_s, 1435 sizeof_vn_nary_op (nary->length)); 1436 memcpy (newnary, nary, sizeof_vn_nary_op (nary->length)); 1437 1438 for (i = 0; i < newnary->length; i++) 1439 { 1440 if (TREE_CODE (newnary->op[i]) != SSA_NAME) 1441 continue; 1442 else 1443 { 1444 pre_expr leader, result; 1445 unsigned int op_val_id = VN_INFO (newnary->op[i])->value_id; 1446 leader = find_leader_in_sets (op_val_id, set1, set2); 1447 result = phi_translate (leader, set1, set2, pred, phiblock); 1448 if (result && result != leader) 1449 newnary->op[i] = get_representative_for (result); 1450 else if (!result) 1451 return NULL; 1452 1453 changed |= newnary->op[i] != nary->op[i]; 1454 } 1455 } 1456 if (changed) 1457 { 1458 pre_expr constant; 1459 unsigned int new_val_id; 1460 1461 PRE_EXPR_NARY (expr) = newnary; 1462 constant = fully_constant_expression (expr); 1463 PRE_EXPR_NARY (expr) = nary; 1464 if (constant != expr) 1465 { 1466 /* For non-CONSTANTs we have to make sure we can eventually 1467 insert the expression. Which means we need to have a 1468 leader for it. */ 1469 if (constant->kind != CONSTANT) 1470 { 1471 /* Do not allow simplifications to non-constants over 1472 backedges as this will likely result in a loop PHI node 1473 to be inserted and increased register pressure. 1474 See PR77498 - this avoids doing predcoms work in 1475 a less efficient way. */ 1476 if (find_edge (pred, phiblock)->flags & EDGE_DFS_BACK) 1477 ; 1478 else 1479 { 1480 unsigned value_id = get_expr_value_id (constant); 1481 constant = find_leader_in_sets (value_id, set1, set2); 1482 if (constant) 1483 return constant; 1484 } 1485 } 1486 else 1487 return constant; 1488 } 1489 1490 tree result = vn_nary_op_lookup_pieces (newnary->length, 1491 newnary->opcode, 1492 newnary->type, 1493 &newnary->op[0], 1494 &nary); 1495 if (result && is_gimple_min_invariant (result)) 1496 return get_or_alloc_expr_for_constant (result); 1497 1498 expr = pre_expr_pool.allocate (); 1499 expr->kind = NARY; 1500 expr->id = 0; 1501 if (nary) 1502 { 1503 PRE_EXPR_NARY (expr) = nary; 1504 new_val_id = nary->value_id; 1505 get_or_alloc_expression_id (expr); 1506 } 1507 else 1508 { 1509 new_val_id = get_next_value_id (); 1510 value_expressions.safe_grow_cleared (get_max_value_id () + 1); 1511 nary = vn_nary_op_insert_pieces (newnary->length, 1512 newnary->opcode, 1513 newnary->type, 1514 &newnary->op[0], 1515 result, new_val_id); 1516 PRE_EXPR_NARY (expr) = nary; 1517 get_or_alloc_expression_id (expr); 1518 } 1519 add_to_value (new_val_id, expr); 1520 } 1521 return expr; 1522 } 1523 break; 1524 1525 case REFERENCE: 1526 { 1527 vn_reference_t ref = PRE_EXPR_REFERENCE (expr); 1528 vec<vn_reference_op_s> operands = ref->operands; 1529 tree vuse = ref->vuse; 1530 tree newvuse = vuse; 1531 vec<vn_reference_op_s> newoperands = vNULL; 1532 bool changed = false, same_valid = true; 1533 unsigned int i, n; 1534 vn_reference_op_t operand; 1535 vn_reference_t newref; 1536 1537 for (i = 0; operands.iterate (i, &operand); i++) 1538 { 1539 pre_expr opresult; 1540 pre_expr leader; 1541 tree op[3]; 1542 tree type = operand->type; 1543 vn_reference_op_s newop = *operand; 1544 op[0] = operand->op0; 1545 op[1] = operand->op1; 1546 op[2] = operand->op2; 1547 for (n = 0; n < 3; ++n) 1548 { 1549 unsigned int op_val_id; 1550 if (!op[n]) 1551 continue; 1552 if (TREE_CODE (op[n]) != SSA_NAME) 1553 { 1554 /* We can't possibly insert these. */ 1555 if (n != 0 1556 && !is_gimple_min_invariant (op[n])) 1557 break; 1558 continue; 1559 } 1560 op_val_id = VN_INFO (op[n])->value_id; 1561 leader = find_leader_in_sets (op_val_id, set1, set2); 1562 opresult = phi_translate (leader, set1, set2, pred, phiblock); 1563 if (opresult && opresult != leader) 1564 { 1565 tree name = get_representative_for (opresult); 1566 changed |= name != op[n]; 1567 op[n] = name; 1568 } 1569 else if (!opresult) 1570 break; 1571 } 1572 if (n != 3) 1573 { 1574 newoperands.release (); 1575 return NULL; 1576 } 1577 if (!changed) 1578 continue; 1579 if (!newoperands.exists ()) 1580 newoperands = operands.copy (); 1581 /* We may have changed from an SSA_NAME to a constant */ 1582 if (newop.opcode == SSA_NAME && TREE_CODE (op[0]) != SSA_NAME) 1583 newop.opcode = TREE_CODE (op[0]); 1584 newop.type = type; 1585 newop.op0 = op[0]; 1586 newop.op1 = op[1]; 1587 newop.op2 = op[2]; 1588 newoperands[i] = newop; 1589 } 1590 gcc_checking_assert (i == operands.length ()); 1591 1592 if (vuse) 1593 { 1594 newvuse = translate_vuse_through_block (newoperands.exists () 1595 ? newoperands : operands, 1596 ref->set, ref->type, 1597 vuse, phiblock, pred, 1598 &same_valid); 1599 if (newvuse == NULL_TREE) 1600 { 1601 newoperands.release (); 1602 return NULL; 1603 } 1604 } 1605 1606 if (changed || newvuse != vuse) 1607 { 1608 unsigned int new_val_id; 1609 pre_expr constant; 1610 1611 tree result = vn_reference_lookup_pieces (newvuse, ref->set, 1612 ref->type, 1613 newoperands.exists () 1614 ? newoperands : operands, 1615 &newref, VN_WALK); 1616 if (result) 1617 newoperands.release (); 1618 1619 /* We can always insert constants, so if we have a partial 1620 redundant constant load of another type try to translate it 1621 to a constant of appropriate type. */ 1622 if (result && is_gimple_min_invariant (result)) 1623 { 1624 tree tem = result; 1625 if (!useless_type_conversion_p (ref->type, TREE_TYPE (result))) 1626 { 1627 tem = fold_unary (VIEW_CONVERT_EXPR, ref->type, result); 1628 if (tem && !is_gimple_min_invariant (tem)) 1629 tem = NULL_TREE; 1630 } 1631 if (tem) 1632 return get_or_alloc_expr_for_constant (tem); 1633 } 1634 1635 /* If we'd have to convert things we would need to validate 1636 if we can insert the translated expression. So fail 1637 here for now - we cannot insert an alias with a different 1638 type in the VN tables either, as that would assert. */ 1639 if (result 1640 && !useless_type_conversion_p (ref->type, TREE_TYPE (result))) 1641 return NULL; 1642 else if (!result && newref 1643 && !useless_type_conversion_p (ref->type, newref->type)) 1644 { 1645 newoperands.release (); 1646 return NULL; 1647 } 1648 1649 expr = pre_expr_pool.allocate (); 1650 expr->kind = REFERENCE; 1651 expr->id = 0; 1652 1653 if (newref) 1654 { 1655 PRE_EXPR_REFERENCE (expr) = newref; 1656 constant = fully_constant_expression (expr); 1657 if (constant != expr) 1658 return constant; 1659 1660 new_val_id = newref->value_id; 1661 get_or_alloc_expression_id (expr); 1662 } 1663 else 1664 { 1665 if (changed || !same_valid) 1666 { 1667 new_val_id = get_next_value_id (); 1668 value_expressions.safe_grow_cleared 1669 (get_max_value_id () + 1); 1670 } 1671 else 1672 new_val_id = ref->value_id; 1673 if (!newoperands.exists ()) 1674 newoperands = operands.copy (); 1675 newref = vn_reference_insert_pieces (newvuse, ref->set, 1676 ref->type, 1677 newoperands, 1678 result, new_val_id); 1679 newoperands = vNULL; 1680 PRE_EXPR_REFERENCE (expr) = newref; 1681 constant = fully_constant_expression (expr); 1682 if (constant != expr) 1683 return constant; 1684 get_or_alloc_expression_id (expr); 1685 } 1686 add_to_value (new_val_id, expr); 1687 } 1688 newoperands.release (); 1689 return expr; 1690 } 1691 break; 1692 1693 case NAME: 1694 { 1695 tree name = PRE_EXPR_NAME (expr); 1696 gimple *def_stmt = SSA_NAME_DEF_STMT (name); 1697 /* If the SSA name is defined by a PHI node in this block, 1698 translate it. */ 1699 if (gimple_code (def_stmt) == GIMPLE_PHI 1700 && gimple_bb (def_stmt) == phiblock) 1701 { 1702 edge e = find_edge (pred, gimple_bb (def_stmt)); 1703 tree def = PHI_ARG_DEF (def_stmt, e->dest_idx); 1704 1705 /* Handle constant. */ 1706 if (is_gimple_min_invariant (def)) 1707 return get_or_alloc_expr_for_constant (def); 1708 1709 return get_or_alloc_expr_for_name (def); 1710 } 1711 /* Otherwise return it unchanged - it will get removed if its 1712 value is not available in PREDs AVAIL_OUT set of expressions 1713 by the subtraction of TMP_GEN. */ 1714 return expr; 1715 } 1716 1717 default: 1718 gcc_unreachable (); 1719 } 1720 } 1721 1722 /* Wrapper around phi_translate_1 providing caching functionality. */ 1723 1724 static pre_expr 1725 phi_translate (pre_expr expr, bitmap_set_t set1, bitmap_set_t set2, 1726 basic_block pred, basic_block phiblock) 1727 { 1728 expr_pred_trans_t slot = NULL; 1729 pre_expr phitrans; 1730 1731 if (!expr) 1732 return NULL; 1733 1734 /* Constants contain no values that need translation. */ 1735 if (expr->kind == CONSTANT) 1736 return expr; 1737 1738 if (value_id_constant_p (get_expr_value_id (expr))) 1739 return expr; 1740 1741 /* Don't add translations of NAMEs as those are cheap to translate. */ 1742 if (expr->kind != NAME) 1743 { 1744 if (phi_trans_add (&slot, expr, pred)) 1745 return slot->v; 1746 /* Store NULL for the value we want to return in the case of 1747 recursing. */ 1748 slot->v = NULL; 1749 } 1750 1751 /* Translate. */ 1752 phitrans = phi_translate_1 (expr, set1, set2, pred, phiblock); 1753 1754 if (slot) 1755 { 1756 if (phitrans) 1757 slot->v = phitrans; 1758 else 1759 /* Remove failed translations again, they cause insert 1760 iteration to not pick up new opportunities reliably. */ 1761 phi_translate_table->remove_elt_with_hash (slot, slot->hashcode); 1762 } 1763 1764 return phitrans; 1765 } 1766 1767 1768 /* For each expression in SET, translate the values through phi nodes 1769 in PHIBLOCK using edge PHIBLOCK->PRED, and store the resulting 1770 expressions in DEST. */ 1771 1772 static void 1773 phi_translate_set (bitmap_set_t dest, bitmap_set_t set, basic_block pred, 1774 basic_block phiblock) 1775 { 1776 vec<pre_expr> exprs; 1777 pre_expr expr; 1778 int i; 1779 1780 if (gimple_seq_empty_p (phi_nodes (phiblock))) 1781 { 1782 bitmap_set_copy (dest, set); 1783 return; 1784 } 1785 1786 exprs = sorted_array_from_bitmap_set (set); 1787 FOR_EACH_VEC_ELT (exprs, i, expr) 1788 { 1789 pre_expr translated; 1790 translated = phi_translate (expr, set, NULL, pred, phiblock); 1791 if (!translated) 1792 continue; 1793 1794 /* We might end up with multiple expressions from SET being 1795 translated to the same value. In this case we do not want 1796 to retain the NARY or REFERENCE expression but prefer a NAME 1797 which would be the leader. */ 1798 if (translated->kind == NAME) 1799 bitmap_value_replace_in_set (dest, translated); 1800 else 1801 bitmap_value_insert_into_set (dest, translated); 1802 } 1803 exprs.release (); 1804 } 1805 1806 /* Find the leader for a value (i.e., the name representing that 1807 value) in a given set, and return it. Return NULL if no leader 1808 is found. */ 1809 1810 static pre_expr 1811 bitmap_find_leader (bitmap_set_t set, unsigned int val) 1812 { 1813 if (value_id_constant_p (val)) 1814 { 1815 unsigned int i; 1816 bitmap_iterator bi; 1817 bitmap exprset = value_expressions[val]; 1818 1819 EXECUTE_IF_SET_IN_BITMAP (exprset, 0, i, bi) 1820 { 1821 pre_expr expr = expression_for_id (i); 1822 if (expr->kind == CONSTANT) 1823 return expr; 1824 } 1825 } 1826 if (bitmap_set_contains_value (set, val)) 1827 { 1828 /* Rather than walk the entire bitmap of expressions, and see 1829 whether any of them has the value we are looking for, we look 1830 at the reverse mapping, which tells us the set of expressions 1831 that have a given value (IE value->expressions with that 1832 value) and see if any of those expressions are in our set. 1833 The number of expressions per value is usually significantly 1834 less than the number of expressions in the set. In fact, for 1835 large testcases, doing it this way is roughly 5-10x faster 1836 than walking the bitmap. 1837 If this is somehow a significant lose for some cases, we can 1838 choose which set to walk based on which set is smaller. */ 1839 unsigned int i; 1840 bitmap_iterator bi; 1841 bitmap exprset = value_expressions[val]; 1842 1843 EXECUTE_IF_AND_IN_BITMAP (exprset, &set->expressions, 0, i, bi) 1844 return expression_for_id (i); 1845 } 1846 return NULL; 1847 } 1848 1849 /* Determine if EXPR, a memory expression, is ANTIC_IN at the top of 1850 BLOCK by seeing if it is not killed in the block. Note that we are 1851 only determining whether there is a store that kills it. Because 1852 of the order in which clean iterates over values, we are guaranteed 1853 that altered operands will have caused us to be eliminated from the 1854 ANTIC_IN set already. */ 1855 1856 static bool 1857 value_dies_in_block_x (pre_expr expr, basic_block block) 1858 { 1859 tree vuse = PRE_EXPR_REFERENCE (expr)->vuse; 1860 vn_reference_t refx = PRE_EXPR_REFERENCE (expr); 1861 gimple *def; 1862 gimple_stmt_iterator gsi; 1863 unsigned id = get_expression_id (expr); 1864 bool res = false; 1865 ao_ref ref; 1866 1867 if (!vuse) 1868 return false; 1869 1870 /* Lookup a previously calculated result. */ 1871 if (EXPR_DIES (block) 1872 && bitmap_bit_p (EXPR_DIES (block), id * 2)) 1873 return bitmap_bit_p (EXPR_DIES (block), id * 2 + 1); 1874 1875 /* A memory expression {e, VUSE} dies in the block if there is a 1876 statement that may clobber e. If, starting statement walk from the 1877 top of the basic block, a statement uses VUSE there can be no kill 1878 inbetween that use and the original statement that loaded {e, VUSE}, 1879 so we can stop walking. */ 1880 ref.base = NULL_TREE; 1881 for (gsi = gsi_start_bb (block); !gsi_end_p (gsi); gsi_next (&gsi)) 1882 { 1883 tree def_vuse, def_vdef; 1884 def = gsi_stmt (gsi); 1885 def_vuse = gimple_vuse (def); 1886 def_vdef = gimple_vdef (def); 1887 1888 /* Not a memory statement. */ 1889 if (!def_vuse) 1890 continue; 1891 1892 /* Not a may-def. */ 1893 if (!def_vdef) 1894 { 1895 /* A load with the same VUSE, we're done. */ 1896 if (def_vuse == vuse) 1897 break; 1898 1899 continue; 1900 } 1901 1902 /* Init ref only if we really need it. */ 1903 if (ref.base == NULL_TREE 1904 && !ao_ref_init_from_vn_reference (&ref, refx->set, refx->type, 1905 refx->operands)) 1906 { 1907 res = true; 1908 break; 1909 } 1910 /* If the statement may clobber expr, it dies. */ 1911 if (stmt_may_clobber_ref_p_1 (def, &ref)) 1912 { 1913 res = true; 1914 break; 1915 } 1916 } 1917 1918 /* Remember the result. */ 1919 if (!EXPR_DIES (block)) 1920 EXPR_DIES (block) = BITMAP_ALLOC (&grand_bitmap_obstack); 1921 bitmap_set_bit (EXPR_DIES (block), id * 2); 1922 if (res) 1923 bitmap_set_bit (EXPR_DIES (block), id * 2 + 1); 1924 1925 return res; 1926 } 1927 1928 1929 /* Determine if OP is valid in SET1 U SET2, which it is when the union 1930 contains its value-id. */ 1931 1932 static bool 1933 op_valid_in_sets (bitmap_set_t set1, bitmap_set_t set2, tree op) 1934 { 1935 if (op && TREE_CODE (op) == SSA_NAME) 1936 { 1937 unsigned int value_id = VN_INFO (op)->value_id; 1938 if (!(bitmap_set_contains_value (set1, value_id) 1939 || (set2 && bitmap_set_contains_value (set2, value_id)))) 1940 return false; 1941 } 1942 return true; 1943 } 1944 1945 /* Determine if the expression EXPR is valid in SET1 U SET2. 1946 ONLY SET2 CAN BE NULL. 1947 This means that we have a leader for each part of the expression 1948 (if it consists of values), or the expression is an SSA_NAME. 1949 For loads/calls, we also see if the vuse is killed in this block. */ 1950 1951 static bool 1952 valid_in_sets (bitmap_set_t set1, bitmap_set_t set2, pre_expr expr) 1953 { 1954 switch (expr->kind) 1955 { 1956 case NAME: 1957 /* By construction all NAMEs are available. Non-available 1958 NAMEs are removed by subtracting TMP_GEN from the sets. */ 1959 return true; 1960 case NARY: 1961 { 1962 unsigned int i; 1963 vn_nary_op_t nary = PRE_EXPR_NARY (expr); 1964 for (i = 0; i < nary->length; i++) 1965 if (!op_valid_in_sets (set1, set2, nary->op[i])) 1966 return false; 1967 return true; 1968 } 1969 break; 1970 case REFERENCE: 1971 { 1972 vn_reference_t ref = PRE_EXPR_REFERENCE (expr); 1973 vn_reference_op_t vro; 1974 unsigned int i; 1975 1976 FOR_EACH_VEC_ELT (ref->operands, i, vro) 1977 { 1978 if (!op_valid_in_sets (set1, set2, vro->op0) 1979 || !op_valid_in_sets (set1, set2, vro->op1) 1980 || !op_valid_in_sets (set1, set2, vro->op2)) 1981 return false; 1982 } 1983 return true; 1984 } 1985 default: 1986 gcc_unreachable (); 1987 } 1988 } 1989 1990 /* Clean the set of expressions that are no longer valid in SET1 or 1991 SET2. This means expressions that are made up of values we have no 1992 leaders for in SET1 or SET2. This version is used for partial 1993 anticipation, which means it is not valid in either ANTIC_IN or 1994 PA_IN. */ 1995 1996 static void 1997 dependent_clean (bitmap_set_t set1, bitmap_set_t set2) 1998 { 1999 vec<pre_expr> exprs = sorted_array_from_bitmap_set (set1); 2000 pre_expr expr; 2001 int i; 2002 2003 FOR_EACH_VEC_ELT (exprs, i, expr) 2004 { 2005 if (!valid_in_sets (set1, set2, expr)) 2006 bitmap_remove_from_set (set1, expr); 2007 } 2008 exprs.release (); 2009 } 2010 2011 /* Clean the set of expressions that are no longer valid in SET. This 2012 means expressions that are made up of values we have no leaders for 2013 in SET. */ 2014 2015 static void 2016 clean (bitmap_set_t set) 2017 { 2018 vec<pre_expr> exprs = sorted_array_from_bitmap_set (set); 2019 pre_expr expr; 2020 int i; 2021 2022 FOR_EACH_VEC_ELT (exprs, i, expr) 2023 { 2024 if (!valid_in_sets (set, NULL, expr)) 2025 bitmap_remove_from_set (set, expr); 2026 } 2027 exprs.release (); 2028 } 2029 2030 /* Clean the set of expressions that are no longer valid in SET because 2031 they are clobbered in BLOCK or because they trap and may not be executed. */ 2032 2033 static void 2034 prune_clobbered_mems (bitmap_set_t set, basic_block block) 2035 { 2036 bitmap_iterator bi; 2037 unsigned i; 2038 pre_expr to_remove = NULL; 2039 2040 FOR_EACH_EXPR_ID_IN_SET (set, i, bi) 2041 { 2042 /* Remove queued expr. */ 2043 if (to_remove) 2044 { 2045 bitmap_remove_from_set (set, to_remove); 2046 to_remove = NULL; 2047 } 2048 2049 pre_expr expr = expression_for_id (i); 2050 if (expr->kind == REFERENCE) 2051 { 2052 vn_reference_t ref = PRE_EXPR_REFERENCE (expr); 2053 if (ref->vuse) 2054 { 2055 gimple *def_stmt = SSA_NAME_DEF_STMT (ref->vuse); 2056 if (!gimple_nop_p (def_stmt) 2057 && ((gimple_bb (def_stmt) != block 2058 && !dominated_by_p (CDI_DOMINATORS, 2059 block, gimple_bb (def_stmt))) 2060 || (gimple_bb (def_stmt) == block 2061 && value_dies_in_block_x (expr, block)))) 2062 to_remove = expr; 2063 } 2064 } 2065 else if (expr->kind == NARY) 2066 { 2067 vn_nary_op_t nary = PRE_EXPR_NARY (expr); 2068 /* If the NARY may trap make sure the block does not contain 2069 a possible exit point. 2070 ??? This is overly conservative if we translate AVAIL_OUT 2071 as the available expression might be after the exit point. */ 2072 if (BB_MAY_NOTRETURN (block) 2073 && vn_nary_may_trap (nary)) 2074 to_remove = expr; 2075 } 2076 } 2077 2078 /* Remove queued expr. */ 2079 if (to_remove) 2080 bitmap_remove_from_set (set, to_remove); 2081 } 2082 2083 static sbitmap has_abnormal_preds; 2084 2085 /* Compute the ANTIC set for BLOCK. 2086 2087 If succs(BLOCK) > 1 then 2088 ANTIC_OUT[BLOCK] = intersection of ANTIC_IN[b] for all succ(BLOCK) 2089 else if succs(BLOCK) == 1 then 2090 ANTIC_OUT[BLOCK] = phi_translate (ANTIC_IN[succ(BLOCK)]) 2091 2092 ANTIC_IN[BLOCK] = clean(ANTIC_OUT[BLOCK] U EXP_GEN[BLOCK] - TMP_GEN[BLOCK]) 2093 2094 Note that clean() is deferred until after the iteration. */ 2095 2096 static bool 2097 compute_antic_aux (basic_block block, bool block_has_abnormal_pred_edge) 2098 { 2099 bool changed = false; 2100 bitmap_set_t S, old, ANTIC_OUT; 2101 bitmap_iterator bi; 2102 unsigned int bii; 2103 edge e; 2104 edge_iterator ei; 2105 bool was_visited = BB_VISITED (block); 2106 2107 old = ANTIC_OUT = S = NULL; 2108 BB_VISITED (block) = 1; 2109 2110 /* If any edges from predecessors are abnormal, antic_in is empty, 2111 so do nothing. */ 2112 if (block_has_abnormal_pred_edge) 2113 goto maybe_dump_sets; 2114 2115 old = ANTIC_IN (block); 2116 ANTIC_OUT = bitmap_set_new (); 2117 2118 /* If the block has no successors, ANTIC_OUT is empty. */ 2119 if (EDGE_COUNT (block->succs) == 0) 2120 ; 2121 /* If we have one successor, we could have some phi nodes to 2122 translate through. */ 2123 else if (single_succ_p (block)) 2124 { 2125 basic_block succ_bb = single_succ (block); 2126 gcc_assert (BB_VISITED (succ_bb)); 2127 phi_translate_set (ANTIC_OUT, ANTIC_IN (succ_bb), block, succ_bb); 2128 } 2129 /* If we have multiple successors, we take the intersection of all of 2130 them. Note that in the case of loop exit phi nodes, we may have 2131 phis to translate through. */ 2132 else 2133 { 2134 size_t i; 2135 basic_block bprime, first = NULL; 2136 2137 auto_vec<basic_block> worklist (EDGE_COUNT (block->succs)); 2138 FOR_EACH_EDGE (e, ei, block->succs) 2139 { 2140 if (!first 2141 && BB_VISITED (e->dest)) 2142 first = e->dest; 2143 else if (BB_VISITED (e->dest)) 2144 worklist.quick_push (e->dest); 2145 else 2146 { 2147 /* Unvisited successors get their ANTIC_IN replaced by the 2148 maximal set to arrive at a maximum ANTIC_IN solution. 2149 We can ignore them in the intersection operation and thus 2150 need not explicitely represent that maximum solution. */ 2151 if (dump_file && (dump_flags & TDF_DETAILS)) 2152 fprintf (dump_file, "ANTIC_IN is MAX on %d->%d\n", 2153 e->src->index, e->dest->index); 2154 } 2155 } 2156 2157 /* Of multiple successors we have to have visited one already 2158 which is guaranteed by iteration order. */ 2159 gcc_assert (first != NULL); 2160 2161 phi_translate_set (ANTIC_OUT, ANTIC_IN (first), block, first); 2162 2163 FOR_EACH_VEC_ELT (worklist, i, bprime) 2164 { 2165 if (!gimple_seq_empty_p (phi_nodes (bprime))) 2166 { 2167 bitmap_set_t tmp = bitmap_set_new (); 2168 phi_translate_set (tmp, ANTIC_IN (bprime), block, bprime); 2169 bitmap_set_and (ANTIC_OUT, tmp); 2170 bitmap_set_free (tmp); 2171 } 2172 else 2173 bitmap_set_and (ANTIC_OUT, ANTIC_IN (bprime)); 2174 } 2175 } 2176 2177 /* Prune expressions that are clobbered in block and thus become 2178 invalid if translated from ANTIC_OUT to ANTIC_IN. */ 2179 prune_clobbered_mems (ANTIC_OUT, block); 2180 2181 /* Generate ANTIC_OUT - TMP_GEN. */ 2182 S = bitmap_set_subtract (ANTIC_OUT, TMP_GEN (block)); 2183 2184 /* Start ANTIC_IN with EXP_GEN - TMP_GEN. */ 2185 ANTIC_IN (block) = bitmap_set_subtract (EXP_GEN (block), 2186 TMP_GEN (block)); 2187 2188 /* Then union in the ANTIC_OUT - TMP_GEN values, 2189 to get ANTIC_OUT U EXP_GEN - TMP_GEN */ 2190 FOR_EACH_EXPR_ID_IN_SET (S, bii, bi) 2191 bitmap_value_insert_into_set (ANTIC_IN (block), 2192 expression_for_id (bii)); 2193 2194 /* clean (ANTIC_IN (block)) is defered to after the iteration converged 2195 because it can cause non-convergence, see for example PR81181. */ 2196 2197 if (!was_visited || !bitmap_set_equal (old, ANTIC_IN (block))) 2198 changed = true; 2199 2200 maybe_dump_sets: 2201 if (dump_file && (dump_flags & TDF_DETAILS)) 2202 { 2203 if (ANTIC_OUT) 2204 print_bitmap_set (dump_file, ANTIC_OUT, "ANTIC_OUT", block->index); 2205 2206 if (changed) 2207 fprintf (dump_file, "[changed] "); 2208 print_bitmap_set (dump_file, ANTIC_IN (block), "ANTIC_IN", 2209 block->index); 2210 2211 if (S) 2212 print_bitmap_set (dump_file, S, "S", block->index); 2213 } 2214 if (old) 2215 bitmap_set_free (old); 2216 if (S) 2217 bitmap_set_free (S); 2218 if (ANTIC_OUT) 2219 bitmap_set_free (ANTIC_OUT); 2220 return changed; 2221 } 2222 2223 /* Compute PARTIAL_ANTIC for BLOCK. 2224 2225 If succs(BLOCK) > 1 then 2226 PA_OUT[BLOCK] = value wise union of PA_IN[b] + all ANTIC_IN not 2227 in ANTIC_OUT for all succ(BLOCK) 2228 else if succs(BLOCK) == 1 then 2229 PA_OUT[BLOCK] = phi_translate (PA_IN[succ(BLOCK)]) 2230 2231 PA_IN[BLOCK] = dependent_clean(PA_OUT[BLOCK] - TMP_GEN[BLOCK] 2232 - ANTIC_IN[BLOCK]) 2233 2234 */ 2235 static void 2236 compute_partial_antic_aux (basic_block block, 2237 bool block_has_abnormal_pred_edge) 2238 { 2239 bitmap_set_t old_PA_IN; 2240 bitmap_set_t PA_OUT; 2241 edge e; 2242 edge_iterator ei; 2243 unsigned long max_pa = PARAM_VALUE (PARAM_MAX_PARTIAL_ANTIC_LENGTH); 2244 2245 old_PA_IN = PA_OUT = NULL; 2246 2247 /* If any edges from predecessors are abnormal, antic_in is empty, 2248 so do nothing. */ 2249 if (block_has_abnormal_pred_edge) 2250 goto maybe_dump_sets; 2251 2252 /* If there are too many partially anticipatable values in the 2253 block, phi_translate_set can take an exponential time: stop 2254 before the translation starts. */ 2255 if (max_pa 2256 && single_succ_p (block) 2257 && bitmap_count_bits (&PA_IN (single_succ (block))->values) > max_pa) 2258 goto maybe_dump_sets; 2259 2260 old_PA_IN = PA_IN (block); 2261 PA_OUT = bitmap_set_new (); 2262 2263 /* If the block has no successors, ANTIC_OUT is empty. */ 2264 if (EDGE_COUNT (block->succs) == 0) 2265 ; 2266 /* If we have one successor, we could have some phi nodes to 2267 translate through. Note that we can't phi translate across DFS 2268 back edges in partial antic, because it uses a union operation on 2269 the successors. For recurrences like IV's, we will end up 2270 generating a new value in the set on each go around (i + 3 (VH.1) 2271 VH.1 + 1 (VH.2), VH.2 + 1 (VH.3), etc), forever. */ 2272 else if (single_succ_p (block)) 2273 { 2274 basic_block succ = single_succ (block); 2275 if (!(single_succ_edge (block)->flags & EDGE_DFS_BACK)) 2276 phi_translate_set (PA_OUT, PA_IN (succ), block, succ); 2277 } 2278 /* If we have multiple successors, we take the union of all of 2279 them. */ 2280 else 2281 { 2282 size_t i; 2283 basic_block bprime; 2284 2285 auto_vec<basic_block> worklist (EDGE_COUNT (block->succs)); 2286 FOR_EACH_EDGE (e, ei, block->succs) 2287 { 2288 if (e->flags & EDGE_DFS_BACK) 2289 continue; 2290 worklist.quick_push (e->dest); 2291 } 2292 if (worklist.length () > 0) 2293 { 2294 FOR_EACH_VEC_ELT (worklist, i, bprime) 2295 { 2296 unsigned int i; 2297 bitmap_iterator bi; 2298 2299 FOR_EACH_EXPR_ID_IN_SET (ANTIC_IN (bprime), i, bi) 2300 bitmap_value_insert_into_set (PA_OUT, 2301 expression_for_id (i)); 2302 if (!gimple_seq_empty_p (phi_nodes (bprime))) 2303 { 2304 bitmap_set_t pa_in = bitmap_set_new (); 2305 phi_translate_set (pa_in, PA_IN (bprime), block, bprime); 2306 FOR_EACH_EXPR_ID_IN_SET (pa_in, i, bi) 2307 bitmap_value_insert_into_set (PA_OUT, 2308 expression_for_id (i)); 2309 bitmap_set_free (pa_in); 2310 } 2311 else 2312 FOR_EACH_EXPR_ID_IN_SET (PA_IN (bprime), i, bi) 2313 bitmap_value_insert_into_set (PA_OUT, 2314 expression_for_id (i)); 2315 } 2316 } 2317 } 2318 2319 /* Prune expressions that are clobbered in block and thus become 2320 invalid if translated from PA_OUT to PA_IN. */ 2321 prune_clobbered_mems (PA_OUT, block); 2322 2323 /* PA_IN starts with PA_OUT - TMP_GEN. 2324 Then we subtract things from ANTIC_IN. */ 2325 PA_IN (block) = bitmap_set_subtract (PA_OUT, TMP_GEN (block)); 2326 2327 /* For partial antic, we want to put back in the phi results, since 2328 we will properly avoid making them partially antic over backedges. */ 2329 bitmap_ior_into (&PA_IN (block)->values, &PHI_GEN (block)->values); 2330 bitmap_ior_into (&PA_IN (block)->expressions, &PHI_GEN (block)->expressions); 2331 2332 /* PA_IN[block] = PA_IN[block] - ANTIC_IN[block] */ 2333 bitmap_set_subtract_values (PA_IN (block), ANTIC_IN (block)); 2334 2335 dependent_clean (PA_IN (block), ANTIC_IN (block)); 2336 2337 maybe_dump_sets: 2338 if (dump_file && (dump_flags & TDF_DETAILS)) 2339 { 2340 if (PA_OUT) 2341 print_bitmap_set (dump_file, PA_OUT, "PA_OUT", block->index); 2342 2343 print_bitmap_set (dump_file, PA_IN (block), "PA_IN", block->index); 2344 } 2345 if (old_PA_IN) 2346 bitmap_set_free (old_PA_IN); 2347 if (PA_OUT) 2348 bitmap_set_free (PA_OUT); 2349 } 2350 2351 /* Compute ANTIC and partial ANTIC sets. */ 2352 2353 static void 2354 compute_antic (void) 2355 { 2356 bool changed = true; 2357 int num_iterations = 0; 2358 basic_block block; 2359 int i; 2360 edge_iterator ei; 2361 edge e; 2362 2363 /* If any predecessor edges are abnormal, we punt, so antic_in is empty. 2364 We pre-build the map of blocks with incoming abnormal edges here. */ 2365 has_abnormal_preds = sbitmap_alloc (last_basic_block_for_fn (cfun)); 2366 bitmap_clear (has_abnormal_preds); 2367 2368 FOR_ALL_BB_FN (block, cfun) 2369 { 2370 BB_VISITED (block) = 0; 2371 2372 FOR_EACH_EDGE (e, ei, block->preds) 2373 if (e->flags & EDGE_ABNORMAL) 2374 { 2375 bitmap_set_bit (has_abnormal_preds, block->index); 2376 2377 /* We also anticipate nothing. */ 2378 BB_VISITED (block) = 1; 2379 break; 2380 } 2381 2382 /* While we are here, give empty ANTIC_IN sets to each block. */ 2383 ANTIC_IN (block) = bitmap_set_new (); 2384 if (do_partial_partial) 2385 PA_IN (block) = bitmap_set_new (); 2386 } 2387 2388 /* At the exit block we anticipate nothing. */ 2389 BB_VISITED (EXIT_BLOCK_PTR_FOR_FN (cfun)) = 1; 2390 2391 /* For ANTIC computation we need a postorder that also guarantees that 2392 a block with a single successor is visited after its successor. 2393 RPO on the inverted CFG has this property. */ 2394 int *postorder = XNEWVEC (int, n_basic_blocks_for_fn (cfun)); 2395 int postorder_num = inverted_post_order_compute (postorder); 2396 2397 auto_sbitmap worklist (last_basic_block_for_fn (cfun) + 1); 2398 bitmap_ones (worklist); 2399 while (changed) 2400 { 2401 if (dump_file && (dump_flags & TDF_DETAILS)) 2402 fprintf (dump_file, "Starting iteration %d\n", num_iterations); 2403 /* ??? We need to clear our PHI translation cache here as the 2404 ANTIC sets shrink and we restrict valid translations to 2405 those having operands with leaders in ANTIC. Same below 2406 for PA ANTIC computation. */ 2407 num_iterations++; 2408 changed = false; 2409 for (i = postorder_num - 1; i >= 0; i--) 2410 { 2411 if (bitmap_bit_p (worklist, postorder[i])) 2412 { 2413 basic_block block = BASIC_BLOCK_FOR_FN (cfun, postorder[i]); 2414 bitmap_clear_bit (worklist, block->index); 2415 if (compute_antic_aux (block, 2416 bitmap_bit_p (has_abnormal_preds, 2417 block->index))) 2418 { 2419 FOR_EACH_EDGE (e, ei, block->preds) 2420 bitmap_set_bit (worklist, e->src->index); 2421 changed = true; 2422 } 2423 } 2424 } 2425 /* Theoretically possible, but *highly* unlikely. */ 2426 gcc_checking_assert (num_iterations < 500); 2427 } 2428 2429 /* We have to clean after the dataflow problem converged as cleaning 2430 can cause non-convergence because it is based on expressions 2431 rather than values. */ 2432 FOR_EACH_BB_FN (block, cfun) 2433 clean (ANTIC_IN (block)); 2434 2435 statistics_histogram_event (cfun, "compute_antic iterations", 2436 num_iterations); 2437 2438 if (do_partial_partial) 2439 { 2440 /* For partial antic we ignore backedges and thus we do not need 2441 to perform any iteration when we process blocks in postorder. */ 2442 postorder_num = pre_and_rev_post_order_compute (NULL, postorder, false); 2443 for (i = postorder_num - 1 ; i >= 0; i--) 2444 { 2445 basic_block block = BASIC_BLOCK_FOR_FN (cfun, postorder[i]); 2446 compute_partial_antic_aux (block, 2447 bitmap_bit_p (has_abnormal_preds, 2448 block->index)); 2449 } 2450 } 2451 2452 sbitmap_free (has_abnormal_preds); 2453 free (postorder); 2454 } 2455 2456 2457 /* Inserted expressions are placed onto this worklist, which is used 2458 for performing quick dead code elimination of insertions we made 2459 that didn't turn out to be necessary. */ 2460 static bitmap inserted_exprs; 2461 2462 /* The actual worker for create_component_ref_by_pieces. */ 2463 2464 static tree 2465 create_component_ref_by_pieces_1 (basic_block block, vn_reference_t ref, 2466 unsigned int *operand, gimple_seq *stmts) 2467 { 2468 vn_reference_op_t currop = &ref->operands[*operand]; 2469 tree genop; 2470 ++*operand; 2471 switch (currop->opcode) 2472 { 2473 case CALL_EXPR: 2474 gcc_unreachable (); 2475 2476 case MEM_REF: 2477 { 2478 tree baseop = create_component_ref_by_pieces_1 (block, ref, operand, 2479 stmts); 2480 if (!baseop) 2481 return NULL_TREE; 2482 tree offset = currop->op0; 2483 if (TREE_CODE (baseop) == ADDR_EXPR 2484 && handled_component_p (TREE_OPERAND (baseop, 0))) 2485 { 2486 HOST_WIDE_INT off; 2487 tree base; 2488 base = get_addr_base_and_unit_offset (TREE_OPERAND (baseop, 0), 2489 &off); 2490 gcc_assert (base); 2491 offset = int_const_binop (PLUS_EXPR, offset, 2492 build_int_cst (TREE_TYPE (offset), 2493 off)); 2494 baseop = build_fold_addr_expr (base); 2495 } 2496 genop = build2 (MEM_REF, currop->type, baseop, offset); 2497 MR_DEPENDENCE_CLIQUE (genop) = currop->clique; 2498 MR_DEPENDENCE_BASE (genop) = currop->base; 2499 REF_REVERSE_STORAGE_ORDER (genop) = currop->reverse; 2500 return genop; 2501 } 2502 2503 case TARGET_MEM_REF: 2504 { 2505 tree genop0 = NULL_TREE, genop1 = NULL_TREE; 2506 vn_reference_op_t nextop = &ref->operands[++*operand]; 2507 tree baseop = create_component_ref_by_pieces_1 (block, ref, operand, 2508 stmts); 2509 if (!baseop) 2510 return NULL_TREE; 2511 if (currop->op0) 2512 { 2513 genop0 = find_or_generate_expression (block, currop->op0, stmts); 2514 if (!genop0) 2515 return NULL_TREE; 2516 } 2517 if (nextop->op0) 2518 { 2519 genop1 = find_or_generate_expression (block, nextop->op0, stmts); 2520 if (!genop1) 2521 return NULL_TREE; 2522 } 2523 genop = build5 (TARGET_MEM_REF, currop->type, 2524 baseop, currop->op2, genop0, currop->op1, genop1); 2525 2526 MR_DEPENDENCE_CLIQUE (genop) = currop->clique; 2527 MR_DEPENDENCE_BASE (genop) = currop->base; 2528 return genop; 2529 } 2530 2531 case ADDR_EXPR: 2532 if (currop->op0) 2533 { 2534 gcc_assert (is_gimple_min_invariant (currop->op0)); 2535 return currop->op0; 2536 } 2537 /* Fallthrough. */ 2538 case REALPART_EXPR: 2539 case IMAGPART_EXPR: 2540 case VIEW_CONVERT_EXPR: 2541 { 2542 tree genop0 = create_component_ref_by_pieces_1 (block, ref, operand, 2543 stmts); 2544 if (!genop0) 2545 return NULL_TREE; 2546 return fold_build1 (currop->opcode, currop->type, genop0); 2547 } 2548 2549 case WITH_SIZE_EXPR: 2550 { 2551 tree genop0 = create_component_ref_by_pieces_1 (block, ref, operand, 2552 stmts); 2553 if (!genop0) 2554 return NULL_TREE; 2555 tree genop1 = find_or_generate_expression (block, currop->op0, stmts); 2556 if (!genop1) 2557 return NULL_TREE; 2558 return fold_build2 (currop->opcode, currop->type, genop0, genop1); 2559 } 2560 2561 case BIT_FIELD_REF: 2562 { 2563 tree genop0 = create_component_ref_by_pieces_1 (block, ref, operand, 2564 stmts); 2565 if (!genop0) 2566 return NULL_TREE; 2567 tree op1 = currop->op0; 2568 tree op2 = currop->op1; 2569 tree t = build3 (BIT_FIELD_REF, currop->type, genop0, op1, op2); 2570 REF_REVERSE_STORAGE_ORDER (t) = currop->reverse; 2571 return fold (t); 2572 } 2573 2574 /* For array ref vn_reference_op's, operand 1 of the array ref 2575 is op0 of the reference op and operand 3 of the array ref is 2576 op1. */ 2577 case ARRAY_RANGE_REF: 2578 case ARRAY_REF: 2579 { 2580 tree genop0; 2581 tree genop1 = currop->op0; 2582 tree genop2 = currop->op1; 2583 tree genop3 = currop->op2; 2584 genop0 = create_component_ref_by_pieces_1 (block, ref, operand, 2585 stmts); 2586 if (!genop0) 2587 return NULL_TREE; 2588 genop1 = find_or_generate_expression (block, genop1, stmts); 2589 if (!genop1) 2590 return NULL_TREE; 2591 if (genop2) 2592 { 2593 tree domain_type = TYPE_DOMAIN (TREE_TYPE (genop0)); 2594 /* Drop zero minimum index if redundant. */ 2595 if (integer_zerop (genop2) 2596 && (!domain_type 2597 || integer_zerop (TYPE_MIN_VALUE (domain_type)))) 2598 genop2 = NULL_TREE; 2599 else 2600 { 2601 genop2 = find_or_generate_expression (block, genop2, stmts); 2602 if (!genop2) 2603 return NULL_TREE; 2604 } 2605 } 2606 if (genop3) 2607 { 2608 tree elmt_type = TREE_TYPE (TREE_TYPE (genop0)); 2609 /* We can't always put a size in units of the element alignment 2610 here as the element alignment may be not visible. See 2611 PR43783. Simply drop the element size for constant 2612 sizes. */ 2613 if (TREE_CODE (genop3) == INTEGER_CST 2614 && TREE_CODE (TYPE_SIZE_UNIT (elmt_type)) == INTEGER_CST 2615 && wi::eq_p (wi::to_offset (TYPE_SIZE_UNIT (elmt_type)), 2616 (wi::to_offset (genop3) 2617 * vn_ref_op_align_unit (currop)))) 2618 genop3 = NULL_TREE; 2619 else 2620 { 2621 genop3 = find_or_generate_expression (block, genop3, stmts); 2622 if (!genop3) 2623 return NULL_TREE; 2624 } 2625 } 2626 return build4 (currop->opcode, currop->type, genop0, genop1, 2627 genop2, genop3); 2628 } 2629 case COMPONENT_REF: 2630 { 2631 tree op0; 2632 tree op1; 2633 tree genop2 = currop->op1; 2634 op0 = create_component_ref_by_pieces_1 (block, ref, operand, stmts); 2635 if (!op0) 2636 return NULL_TREE; 2637 /* op1 should be a FIELD_DECL, which are represented by themselves. */ 2638 op1 = currop->op0; 2639 if (genop2) 2640 { 2641 genop2 = find_or_generate_expression (block, genop2, stmts); 2642 if (!genop2) 2643 return NULL_TREE; 2644 } 2645 return fold_build3 (COMPONENT_REF, TREE_TYPE (op1), op0, op1, genop2); 2646 } 2647 2648 case SSA_NAME: 2649 { 2650 genop = find_or_generate_expression (block, currop->op0, stmts); 2651 return genop; 2652 } 2653 case STRING_CST: 2654 case INTEGER_CST: 2655 case COMPLEX_CST: 2656 case VECTOR_CST: 2657 case REAL_CST: 2658 case CONSTRUCTOR: 2659 case VAR_DECL: 2660 case PARM_DECL: 2661 case CONST_DECL: 2662 case RESULT_DECL: 2663 case FUNCTION_DECL: 2664 return currop->op0; 2665 2666 default: 2667 gcc_unreachable (); 2668 } 2669 } 2670 2671 /* For COMPONENT_REF's and ARRAY_REF's, we can't have any intermediates for the 2672 COMPONENT_REF or MEM_REF or ARRAY_REF portion, because we'd end up with 2673 trying to rename aggregates into ssa form directly, which is a no no. 2674 2675 Thus, this routine doesn't create temporaries, it just builds a 2676 single access expression for the array, calling 2677 find_or_generate_expression to build the innermost pieces. 2678 2679 This function is a subroutine of create_expression_by_pieces, and 2680 should not be called on it's own unless you really know what you 2681 are doing. */ 2682 2683 static tree 2684 create_component_ref_by_pieces (basic_block block, vn_reference_t ref, 2685 gimple_seq *stmts) 2686 { 2687 unsigned int op = 0; 2688 return create_component_ref_by_pieces_1 (block, ref, &op, stmts); 2689 } 2690 2691 /* Find a simple leader for an expression, or generate one using 2692 create_expression_by_pieces from a NARY expression for the value. 2693 BLOCK is the basic_block we are looking for leaders in. 2694 OP is the tree expression to find a leader for or generate. 2695 Returns the leader or NULL_TREE on failure. */ 2696 2697 static tree 2698 find_or_generate_expression (basic_block block, tree op, gimple_seq *stmts) 2699 { 2700 pre_expr expr = get_or_alloc_expr_for (op); 2701 unsigned int lookfor = get_expr_value_id (expr); 2702 pre_expr leader = bitmap_find_leader (AVAIL_OUT (block), lookfor); 2703 if (leader) 2704 { 2705 if (leader->kind == NAME) 2706 return PRE_EXPR_NAME (leader); 2707 else if (leader->kind == CONSTANT) 2708 return PRE_EXPR_CONSTANT (leader); 2709 2710 /* Defer. */ 2711 return NULL_TREE; 2712 } 2713 2714 /* It must be a complex expression, so generate it recursively. Note 2715 that this is only necessary to handle gcc.dg/tree-ssa/ssa-pre28.c 2716 where the insert algorithm fails to insert a required expression. */ 2717 bitmap exprset = value_expressions[lookfor]; 2718 bitmap_iterator bi; 2719 unsigned int i; 2720 EXECUTE_IF_SET_IN_BITMAP (exprset, 0, i, bi) 2721 { 2722 pre_expr temp = expression_for_id (i); 2723 /* We cannot insert random REFERENCE expressions at arbitrary 2724 places. We can insert NARYs which eventually re-materializes 2725 its operand values. */ 2726 if (temp->kind == NARY) 2727 return create_expression_by_pieces (block, temp, stmts, 2728 get_expr_type (expr)); 2729 } 2730 2731 /* Defer. */ 2732 return NULL_TREE; 2733 } 2734 2735 #define NECESSARY GF_PLF_1 2736 2737 /* Create an expression in pieces, so that we can handle very complex 2738 expressions that may be ANTIC, but not necessary GIMPLE. 2739 BLOCK is the basic block the expression will be inserted into, 2740 EXPR is the expression to insert (in value form) 2741 STMTS is a statement list to append the necessary insertions into. 2742 2743 This function will die if we hit some value that shouldn't be 2744 ANTIC but is (IE there is no leader for it, or its components). 2745 The function returns NULL_TREE in case a different antic expression 2746 has to be inserted first. 2747 This function may also generate expressions that are themselves 2748 partially or fully redundant. Those that are will be either made 2749 fully redundant during the next iteration of insert (for partially 2750 redundant ones), or eliminated by eliminate (for fully redundant 2751 ones). */ 2752 2753 static tree 2754 create_expression_by_pieces (basic_block block, pre_expr expr, 2755 gimple_seq *stmts, tree type) 2756 { 2757 tree name; 2758 tree folded; 2759 gimple_seq forced_stmts = NULL; 2760 unsigned int value_id; 2761 gimple_stmt_iterator gsi; 2762 tree exprtype = type ? type : get_expr_type (expr); 2763 pre_expr nameexpr; 2764 gassign *newstmt; 2765 2766 switch (expr->kind) 2767 { 2768 /* We may hit the NAME/CONSTANT case if we have to convert types 2769 that value numbering saw through. */ 2770 case NAME: 2771 folded = PRE_EXPR_NAME (expr); 2772 if (useless_type_conversion_p (exprtype, TREE_TYPE (folded))) 2773 return folded; 2774 break; 2775 case CONSTANT: 2776 { 2777 folded = PRE_EXPR_CONSTANT (expr); 2778 tree tem = fold_convert (exprtype, folded); 2779 if (is_gimple_min_invariant (tem)) 2780 return tem; 2781 break; 2782 } 2783 case REFERENCE: 2784 if (PRE_EXPR_REFERENCE (expr)->operands[0].opcode == CALL_EXPR) 2785 { 2786 vn_reference_t ref = PRE_EXPR_REFERENCE (expr); 2787 unsigned int operand = 1; 2788 vn_reference_op_t currop = &ref->operands[0]; 2789 tree sc = NULL_TREE; 2790 tree fn = find_or_generate_expression (block, currop->op0, stmts); 2791 if (!fn) 2792 return NULL_TREE; 2793 if (currop->op1) 2794 { 2795 sc = find_or_generate_expression (block, currop->op1, stmts); 2796 if (!sc) 2797 return NULL_TREE; 2798 } 2799 auto_vec<tree> args (ref->operands.length () - 1); 2800 while (operand < ref->operands.length ()) 2801 { 2802 tree arg = create_component_ref_by_pieces_1 (block, ref, 2803 &operand, stmts); 2804 if (!arg) 2805 return NULL_TREE; 2806 args.quick_push (arg); 2807 } 2808 gcall *call = gimple_build_call_vec (fn, args); 2809 gimple_call_set_with_bounds (call, currop->with_bounds); 2810 if (sc) 2811 gimple_call_set_chain (call, sc); 2812 tree forcedname = make_ssa_name (currop->type); 2813 gimple_call_set_lhs (call, forcedname); 2814 /* There's no CCP pass after PRE which would re-compute alignment 2815 information so make sure we re-materialize this here. */ 2816 if (gimple_call_builtin_p (call, BUILT_IN_ASSUME_ALIGNED) 2817 && args.length () - 2 <= 1 2818 && tree_fits_uhwi_p (args[1]) 2819 && (args.length () != 3 || tree_fits_uhwi_p (args[2]))) 2820 { 2821 unsigned HOST_WIDE_INT halign = tree_to_uhwi (args[1]); 2822 unsigned HOST_WIDE_INT hmisalign 2823 = args.length () == 3 ? tree_to_uhwi (args[2]) : 0; 2824 if ((halign & (halign - 1)) == 0 2825 && (hmisalign & ~(halign - 1)) == 0) 2826 set_ptr_info_alignment (get_ptr_info (forcedname), 2827 halign, hmisalign); 2828 } 2829 gimple_set_vuse (call, BB_LIVE_VOP_ON_EXIT (block)); 2830 gimple_seq_add_stmt_without_update (&forced_stmts, call); 2831 folded = forcedname; 2832 } 2833 else 2834 { 2835 folded = create_component_ref_by_pieces (block, 2836 PRE_EXPR_REFERENCE (expr), 2837 stmts); 2838 if (!folded) 2839 return NULL_TREE; 2840 name = make_temp_ssa_name (exprtype, NULL, "pretmp"); 2841 newstmt = gimple_build_assign (name, folded); 2842 gimple_seq_add_stmt_without_update (&forced_stmts, newstmt); 2843 gimple_set_vuse (newstmt, BB_LIVE_VOP_ON_EXIT (block)); 2844 folded = name; 2845 } 2846 break; 2847 case NARY: 2848 { 2849 vn_nary_op_t nary = PRE_EXPR_NARY (expr); 2850 tree *genop = XALLOCAVEC (tree, nary->length); 2851 unsigned i; 2852 for (i = 0; i < nary->length; ++i) 2853 { 2854 genop[i] = find_or_generate_expression (block, nary->op[i], stmts); 2855 if (!genop[i]) 2856 return NULL_TREE; 2857 /* Ensure genop[] is properly typed for POINTER_PLUS_EXPR. It 2858 may have conversions stripped. */ 2859 if (nary->opcode == POINTER_PLUS_EXPR) 2860 { 2861 if (i == 0) 2862 genop[i] = gimple_convert (&forced_stmts, 2863 nary->type, genop[i]); 2864 else if (i == 1) 2865 genop[i] = gimple_convert (&forced_stmts, 2866 sizetype, genop[i]); 2867 } 2868 else 2869 genop[i] = gimple_convert (&forced_stmts, 2870 TREE_TYPE (nary->op[i]), genop[i]); 2871 } 2872 if (nary->opcode == CONSTRUCTOR) 2873 { 2874 vec<constructor_elt, va_gc> *elts = NULL; 2875 for (i = 0; i < nary->length; ++i) 2876 CONSTRUCTOR_APPEND_ELT (elts, NULL_TREE, genop[i]); 2877 folded = build_constructor (nary->type, elts); 2878 name = make_temp_ssa_name (exprtype, NULL, "pretmp"); 2879 newstmt = gimple_build_assign (name, folded); 2880 gimple_seq_add_stmt_without_update (&forced_stmts, newstmt); 2881 folded = name; 2882 } 2883 else 2884 { 2885 switch (nary->length) 2886 { 2887 case 1: 2888 folded = gimple_build (&forced_stmts, nary->opcode, nary->type, 2889 genop[0]); 2890 break; 2891 case 2: 2892 folded = gimple_build (&forced_stmts, nary->opcode, nary->type, 2893 genop[0], genop[1]); 2894 break; 2895 case 3: 2896 folded = gimple_build (&forced_stmts, nary->opcode, nary->type, 2897 genop[0], genop[1], genop[2]); 2898 break; 2899 default: 2900 gcc_unreachable (); 2901 } 2902 } 2903 } 2904 break; 2905 default: 2906 gcc_unreachable (); 2907 } 2908 2909 folded = gimple_convert (&forced_stmts, exprtype, folded); 2910 2911 /* If there is nothing to insert, return the simplified result. */ 2912 if (gimple_seq_empty_p (forced_stmts)) 2913 return folded; 2914 /* If we simplified to a constant return it and discard eventually 2915 built stmts. */ 2916 if (is_gimple_min_invariant (folded)) 2917 { 2918 gimple_seq_discard (forced_stmts); 2919 return folded; 2920 } 2921 /* Likewise if we simplified to sth not queued for insertion. */ 2922 bool found = false; 2923 gsi = gsi_last (forced_stmts); 2924 for (; !gsi_end_p (gsi); gsi_prev (&gsi)) 2925 { 2926 gimple *stmt = gsi_stmt (gsi); 2927 tree forcedname = gimple_get_lhs (stmt); 2928 if (forcedname == folded) 2929 { 2930 found = true; 2931 break; 2932 } 2933 } 2934 if (! found) 2935 { 2936 gimple_seq_discard (forced_stmts); 2937 return folded; 2938 } 2939 gcc_assert (TREE_CODE (folded) == SSA_NAME); 2940 2941 /* If we have any intermediate expressions to the value sets, add them 2942 to the value sets and chain them in the instruction stream. */ 2943 if (forced_stmts) 2944 { 2945 gsi = gsi_start (forced_stmts); 2946 for (; !gsi_end_p (gsi); gsi_next (&gsi)) 2947 { 2948 gimple *stmt = gsi_stmt (gsi); 2949 tree forcedname = gimple_get_lhs (stmt); 2950 pre_expr nameexpr; 2951 2952 if (forcedname != folded) 2953 { 2954 VN_INFO_GET (forcedname)->valnum = forcedname; 2955 VN_INFO (forcedname)->value_id = get_next_value_id (); 2956 nameexpr = get_or_alloc_expr_for_name (forcedname); 2957 add_to_value (VN_INFO (forcedname)->value_id, nameexpr); 2958 bitmap_value_replace_in_set (NEW_SETS (block), nameexpr); 2959 bitmap_value_replace_in_set (AVAIL_OUT (block), nameexpr); 2960 } 2961 2962 bitmap_set_bit (inserted_exprs, SSA_NAME_VERSION (forcedname)); 2963 gimple_set_plf (stmt, NECESSARY, false); 2964 } 2965 gimple_seq_add_seq (stmts, forced_stmts); 2966 } 2967 2968 name = folded; 2969 2970 /* Fold the last statement. */ 2971 gsi = gsi_last (*stmts); 2972 if (fold_stmt_inplace (&gsi)) 2973 update_stmt (gsi_stmt (gsi)); 2974 2975 /* Add a value number to the temporary. 2976 The value may already exist in either NEW_SETS, or AVAIL_OUT, because 2977 we are creating the expression by pieces, and this particular piece of 2978 the expression may have been represented. There is no harm in replacing 2979 here. */ 2980 value_id = get_expr_value_id (expr); 2981 VN_INFO_GET (name)->value_id = value_id; 2982 VN_INFO (name)->valnum = sccvn_valnum_from_value_id (value_id); 2983 if (VN_INFO (name)->valnum == NULL_TREE) 2984 VN_INFO (name)->valnum = name; 2985 gcc_assert (VN_INFO (name)->valnum != NULL_TREE); 2986 nameexpr = get_or_alloc_expr_for_name (name); 2987 add_to_value (value_id, nameexpr); 2988 if (NEW_SETS (block)) 2989 bitmap_value_replace_in_set (NEW_SETS (block), nameexpr); 2990 bitmap_value_replace_in_set (AVAIL_OUT (block), nameexpr); 2991 2992 pre_stats.insertions++; 2993 if (dump_file && (dump_flags & TDF_DETAILS)) 2994 { 2995 fprintf (dump_file, "Inserted "); 2996 print_gimple_stmt (dump_file, gsi_stmt (gsi_last (*stmts)), 0, 0); 2997 fprintf (dump_file, " in predecessor %d (%04d)\n", 2998 block->index, value_id); 2999 } 3000 3001 return name; 3002 } 3003 3004 3005 /* Insert the to-be-made-available values of expression EXPRNUM for each 3006 predecessor, stored in AVAIL, into the predecessors of BLOCK, and 3007 merge the result with a phi node, given the same value number as 3008 NODE. Return true if we have inserted new stuff. */ 3009 3010 static bool 3011 insert_into_preds_of_block (basic_block block, unsigned int exprnum, 3012 vec<pre_expr> avail) 3013 { 3014 pre_expr expr = expression_for_id (exprnum); 3015 pre_expr newphi; 3016 unsigned int val = get_expr_value_id (expr); 3017 edge pred; 3018 bool insertions = false; 3019 bool nophi = false; 3020 basic_block bprime; 3021 pre_expr eprime; 3022 edge_iterator ei; 3023 tree type = get_expr_type (expr); 3024 tree temp; 3025 gphi *phi; 3026 3027 /* Make sure we aren't creating an induction variable. */ 3028 if (bb_loop_depth (block) > 0 && EDGE_COUNT (block->preds) == 2) 3029 { 3030 bool firstinsideloop = false; 3031 bool secondinsideloop = false; 3032 firstinsideloop = flow_bb_inside_loop_p (block->loop_father, 3033 EDGE_PRED (block, 0)->src); 3034 secondinsideloop = flow_bb_inside_loop_p (block->loop_father, 3035 EDGE_PRED (block, 1)->src); 3036 /* Induction variables only have one edge inside the loop. */ 3037 if ((firstinsideloop ^ secondinsideloop) 3038 && expr->kind != REFERENCE) 3039 { 3040 if (dump_file && (dump_flags & TDF_DETAILS)) 3041 fprintf (dump_file, "Skipping insertion of phi for partial redundancy: Looks like an induction variable\n"); 3042 nophi = true; 3043 } 3044 } 3045 3046 /* Make the necessary insertions. */ 3047 FOR_EACH_EDGE (pred, ei, block->preds) 3048 { 3049 gimple_seq stmts = NULL; 3050 tree builtexpr; 3051 bprime = pred->src; 3052 eprime = avail[pred->dest_idx]; 3053 builtexpr = create_expression_by_pieces (bprime, eprime, 3054 &stmts, type); 3055 gcc_assert (!(pred->flags & EDGE_ABNORMAL)); 3056 if (!gimple_seq_empty_p (stmts)) 3057 { 3058 gsi_insert_seq_on_edge (pred, stmts); 3059 insertions = true; 3060 } 3061 if (!builtexpr) 3062 { 3063 /* We cannot insert a PHI node if we failed to insert 3064 on one edge. */ 3065 nophi = true; 3066 continue; 3067 } 3068 if (is_gimple_min_invariant (builtexpr)) 3069 avail[pred->dest_idx] = get_or_alloc_expr_for_constant (builtexpr); 3070 else 3071 avail[pred->dest_idx] = get_or_alloc_expr_for_name (builtexpr); 3072 } 3073 /* If we didn't want a phi node, and we made insertions, we still have 3074 inserted new stuff, and thus return true. If we didn't want a phi node, 3075 and didn't make insertions, we haven't added anything new, so return 3076 false. */ 3077 if (nophi && insertions) 3078 return true; 3079 else if (nophi && !insertions) 3080 return false; 3081 3082 /* Now build a phi for the new variable. */ 3083 temp = make_temp_ssa_name (type, NULL, "prephitmp"); 3084 phi = create_phi_node (temp, block); 3085 3086 gimple_set_plf (phi, NECESSARY, false); 3087 VN_INFO_GET (temp)->value_id = val; 3088 VN_INFO (temp)->valnum = sccvn_valnum_from_value_id (val); 3089 if (VN_INFO (temp)->valnum == NULL_TREE) 3090 VN_INFO (temp)->valnum = temp; 3091 bitmap_set_bit (inserted_exprs, SSA_NAME_VERSION (temp)); 3092 FOR_EACH_EDGE (pred, ei, block->preds) 3093 { 3094 pre_expr ae = avail[pred->dest_idx]; 3095 gcc_assert (get_expr_type (ae) == type 3096 || useless_type_conversion_p (type, get_expr_type (ae))); 3097 if (ae->kind == CONSTANT) 3098 add_phi_arg (phi, unshare_expr (PRE_EXPR_CONSTANT (ae)), 3099 pred, UNKNOWN_LOCATION); 3100 else 3101 add_phi_arg (phi, PRE_EXPR_NAME (ae), pred, UNKNOWN_LOCATION); 3102 } 3103 3104 newphi = get_or_alloc_expr_for_name (temp); 3105 add_to_value (val, newphi); 3106 3107 /* The value should *not* exist in PHI_GEN, or else we wouldn't be doing 3108 this insertion, since we test for the existence of this value in PHI_GEN 3109 before proceeding with the partial redundancy checks in insert_aux. 3110 3111 The value may exist in AVAIL_OUT, in particular, it could be represented 3112 by the expression we are trying to eliminate, in which case we want the 3113 replacement to occur. If it's not existing in AVAIL_OUT, we want it 3114 inserted there. 3115 3116 Similarly, to the PHI_GEN case, the value should not exist in NEW_SETS of 3117 this block, because if it did, it would have existed in our dominator's 3118 AVAIL_OUT, and would have been skipped due to the full redundancy check. 3119 */ 3120 3121 bitmap_insert_into_set (PHI_GEN (block), newphi); 3122 bitmap_value_replace_in_set (AVAIL_OUT (block), 3123 newphi); 3124 bitmap_insert_into_set (NEW_SETS (block), 3125 newphi); 3126 3127 /* If we insert a PHI node for a conversion of another PHI node 3128 in the same basic-block try to preserve range information. 3129 This is important so that followup loop passes receive optimal 3130 number of iteration analysis results. See PR61743. */ 3131 if (expr->kind == NARY 3132 && CONVERT_EXPR_CODE_P (expr->u.nary->opcode) 3133 && TREE_CODE (expr->u.nary->op[0]) == SSA_NAME 3134 && gimple_bb (SSA_NAME_DEF_STMT (expr->u.nary->op[0])) == block 3135 && INTEGRAL_TYPE_P (type) 3136 && INTEGRAL_TYPE_P (TREE_TYPE (expr->u.nary->op[0])) 3137 && (TYPE_PRECISION (type) 3138 >= TYPE_PRECISION (TREE_TYPE (expr->u.nary->op[0]))) 3139 && SSA_NAME_RANGE_INFO (expr->u.nary->op[0])) 3140 { 3141 wide_int min, max; 3142 if (get_range_info (expr->u.nary->op[0], &min, &max) == VR_RANGE 3143 && !wi::neg_p (min, SIGNED) 3144 && !wi::neg_p (max, SIGNED)) 3145 /* Just handle extension and sign-changes of all-positive ranges. */ 3146 set_range_info (temp, 3147 SSA_NAME_RANGE_TYPE (expr->u.nary->op[0]), 3148 wide_int_storage::from (min, TYPE_PRECISION (type), 3149 TYPE_SIGN (type)), 3150 wide_int_storage::from (max, TYPE_PRECISION (type), 3151 TYPE_SIGN (type))); 3152 } 3153 3154 if (dump_file && (dump_flags & TDF_DETAILS)) 3155 { 3156 fprintf (dump_file, "Created phi "); 3157 print_gimple_stmt (dump_file, phi, 0, 0); 3158 fprintf (dump_file, " in block %d (%04d)\n", block->index, val); 3159 } 3160 pre_stats.phis++; 3161 return true; 3162 } 3163 3164 3165 3166 /* Perform insertion of partially redundant or hoistable values. 3167 For BLOCK, do the following: 3168 1. Propagate the NEW_SETS of the dominator into the current block. 3169 If the block has multiple predecessors, 3170 2a. Iterate over the ANTIC expressions for the block to see if 3171 any of them are partially redundant. 3172 2b. If so, insert them into the necessary predecessors to make 3173 the expression fully redundant. 3174 2c. Insert a new PHI merging the values of the predecessors. 3175 2d. Insert the new PHI, and the new expressions, into the 3176 NEW_SETS set. 3177 If the block has multiple successors, 3178 3a. Iterate over the ANTIC values for the block to see if 3179 any of them are good candidates for hoisting. 3180 3b. If so, insert expressions computing the values in BLOCK, 3181 and add the new expressions into the NEW_SETS set. 3182 4. Recursively call ourselves on the dominator children of BLOCK. 3183 3184 Steps 1, 2a, and 4 are done by insert_aux. 2b, 2c and 2d are done by 3185 do_pre_regular_insertion and do_partial_insertion. 3a and 3b are 3186 done in do_hoist_insertion. 3187 */ 3188 3189 static bool 3190 do_pre_regular_insertion (basic_block block, basic_block dom) 3191 { 3192 bool new_stuff = false; 3193 vec<pre_expr> exprs; 3194 pre_expr expr; 3195 auto_vec<pre_expr> avail; 3196 int i; 3197 3198 exprs = sorted_array_from_bitmap_set (ANTIC_IN (block)); 3199 avail.safe_grow (EDGE_COUNT (block->preds)); 3200 3201 FOR_EACH_VEC_ELT (exprs, i, expr) 3202 { 3203 if (expr->kind == NARY 3204 || expr->kind == REFERENCE) 3205 { 3206 unsigned int val; 3207 bool by_some = false; 3208 bool cant_insert = false; 3209 bool all_same = true; 3210 pre_expr first_s = NULL; 3211 edge pred; 3212 basic_block bprime; 3213 pre_expr eprime = NULL; 3214 edge_iterator ei; 3215 pre_expr edoubleprime = NULL; 3216 bool do_insertion = false; 3217 3218 val = get_expr_value_id (expr); 3219 if (bitmap_set_contains_value (PHI_GEN (block), val)) 3220 continue; 3221 if (bitmap_set_contains_value (AVAIL_OUT (dom), val)) 3222 { 3223 if (dump_file && (dump_flags & TDF_DETAILS)) 3224 { 3225 fprintf (dump_file, "Found fully redundant value: "); 3226 print_pre_expr (dump_file, expr); 3227 fprintf (dump_file, "\n"); 3228 } 3229 continue; 3230 } 3231 3232 FOR_EACH_EDGE (pred, ei, block->preds) 3233 { 3234 unsigned int vprime; 3235 3236 /* We should never run insertion for the exit block 3237 and so not come across fake pred edges. */ 3238 gcc_assert (!(pred->flags & EDGE_FAKE)); 3239 bprime = pred->src; 3240 /* We are looking at ANTIC_OUT of bprime. */ 3241 eprime = phi_translate (expr, ANTIC_IN (block), NULL, 3242 bprime, block); 3243 3244 /* eprime will generally only be NULL if the 3245 value of the expression, translated 3246 through the PHI for this predecessor, is 3247 undefined. If that is the case, we can't 3248 make the expression fully redundant, 3249 because its value is undefined along a 3250 predecessor path. We can thus break out 3251 early because it doesn't matter what the 3252 rest of the results are. */ 3253 if (eprime == NULL) 3254 { 3255 avail[pred->dest_idx] = NULL; 3256 cant_insert = true; 3257 break; 3258 } 3259 3260 vprime = get_expr_value_id (eprime); 3261 edoubleprime = bitmap_find_leader (AVAIL_OUT (bprime), 3262 vprime); 3263 if (edoubleprime == NULL) 3264 { 3265 avail[pred->dest_idx] = eprime; 3266 all_same = false; 3267 } 3268 else 3269 { 3270 avail[pred->dest_idx] = edoubleprime; 3271 by_some = true; 3272 /* We want to perform insertions to remove a redundancy on 3273 a path in the CFG we want to optimize for speed. */ 3274 if (optimize_edge_for_speed_p (pred)) 3275 do_insertion = true; 3276 if (first_s == NULL) 3277 first_s = edoubleprime; 3278 else if (!pre_expr_d::equal (first_s, edoubleprime)) 3279 all_same = false; 3280 } 3281 } 3282 /* If we can insert it, it's not the same value 3283 already existing along every predecessor, and 3284 it's defined by some predecessor, it is 3285 partially redundant. */ 3286 if (!cant_insert && !all_same && by_some) 3287 { 3288 if (!do_insertion) 3289 { 3290 if (dump_file && (dump_flags & TDF_DETAILS)) 3291 { 3292 fprintf (dump_file, "Skipping partial redundancy for " 3293 "expression "); 3294 print_pre_expr (dump_file, expr); 3295 fprintf (dump_file, " (%04d), no redundancy on to be " 3296 "optimized for speed edge\n", val); 3297 } 3298 } 3299 else if (dbg_cnt (treepre_insert)) 3300 { 3301 if (dump_file && (dump_flags & TDF_DETAILS)) 3302 { 3303 fprintf (dump_file, "Found partial redundancy for " 3304 "expression "); 3305 print_pre_expr (dump_file, expr); 3306 fprintf (dump_file, " (%04d)\n", 3307 get_expr_value_id (expr)); 3308 } 3309 if (insert_into_preds_of_block (block, 3310 get_expression_id (expr), 3311 avail)) 3312 new_stuff = true; 3313 } 3314 } 3315 /* If all edges produce the same value and that value is 3316 an invariant, then the PHI has the same value on all 3317 edges. Note this. */ 3318 else if (!cant_insert && all_same) 3319 { 3320 gcc_assert (edoubleprime->kind == CONSTANT 3321 || edoubleprime->kind == NAME); 3322 3323 tree temp = make_temp_ssa_name (get_expr_type (expr), 3324 NULL, "pretmp"); 3325 gassign *assign 3326 = gimple_build_assign (temp, 3327 edoubleprime->kind == CONSTANT ? 3328 PRE_EXPR_CONSTANT (edoubleprime) : 3329 PRE_EXPR_NAME (edoubleprime)); 3330 gimple_stmt_iterator gsi = gsi_after_labels (block); 3331 gsi_insert_before (&gsi, assign, GSI_NEW_STMT); 3332 3333 gimple_set_plf (assign, NECESSARY, false); 3334 VN_INFO_GET (temp)->value_id = val; 3335 VN_INFO (temp)->valnum = sccvn_valnum_from_value_id (val); 3336 if (VN_INFO (temp)->valnum == NULL_TREE) 3337 VN_INFO (temp)->valnum = temp; 3338 bitmap_set_bit (inserted_exprs, SSA_NAME_VERSION (temp)); 3339 pre_expr newe = get_or_alloc_expr_for_name (temp); 3340 add_to_value (val, newe); 3341 bitmap_value_replace_in_set (AVAIL_OUT (block), newe); 3342 bitmap_insert_into_set (NEW_SETS (block), newe); 3343 } 3344 } 3345 } 3346 3347 exprs.release (); 3348 return new_stuff; 3349 } 3350 3351 3352 /* Perform insertion for partially anticipatable expressions. There 3353 is only one case we will perform insertion for these. This case is 3354 if the expression is partially anticipatable, and fully available. 3355 In this case, we know that putting it earlier will enable us to 3356 remove the later computation. */ 3357 3358 static bool 3359 do_pre_partial_partial_insertion (basic_block block, basic_block dom) 3360 { 3361 bool new_stuff = false; 3362 vec<pre_expr> exprs; 3363 pre_expr expr; 3364 auto_vec<pre_expr> avail; 3365 int i; 3366 3367 exprs = sorted_array_from_bitmap_set (PA_IN (block)); 3368 avail.safe_grow (EDGE_COUNT (block->preds)); 3369 3370 FOR_EACH_VEC_ELT (exprs, i, expr) 3371 { 3372 if (expr->kind == NARY 3373 || expr->kind == REFERENCE) 3374 { 3375 unsigned int val; 3376 bool by_all = true; 3377 bool cant_insert = false; 3378 edge pred; 3379 basic_block bprime; 3380 pre_expr eprime = NULL; 3381 edge_iterator ei; 3382 3383 val = get_expr_value_id (expr); 3384 if (bitmap_set_contains_value (PHI_GEN (block), val)) 3385 continue; 3386 if (bitmap_set_contains_value (AVAIL_OUT (dom), val)) 3387 continue; 3388 3389 FOR_EACH_EDGE (pred, ei, block->preds) 3390 { 3391 unsigned int vprime; 3392 pre_expr edoubleprime; 3393 3394 /* We should never run insertion for the exit block 3395 and so not come across fake pred edges. */ 3396 gcc_assert (!(pred->flags & EDGE_FAKE)); 3397 bprime = pred->src; 3398 eprime = phi_translate (expr, ANTIC_IN (block), 3399 PA_IN (block), 3400 bprime, block); 3401 3402 /* eprime will generally only be NULL if the 3403 value of the expression, translated 3404 through the PHI for this predecessor, is 3405 undefined. If that is the case, we can't 3406 make the expression fully redundant, 3407 because its value is undefined along a 3408 predecessor path. We can thus break out 3409 early because it doesn't matter what the 3410 rest of the results are. */ 3411 if (eprime == NULL) 3412 { 3413 avail[pred->dest_idx] = NULL; 3414 cant_insert = true; 3415 break; 3416 } 3417 3418 vprime = get_expr_value_id (eprime); 3419 edoubleprime = bitmap_find_leader (AVAIL_OUT (bprime), vprime); 3420 avail[pred->dest_idx] = edoubleprime; 3421 if (edoubleprime == NULL) 3422 { 3423 by_all = false; 3424 break; 3425 } 3426 } 3427 3428 /* If we can insert it, it's not the same value 3429 already existing along every predecessor, and 3430 it's defined by some predecessor, it is 3431 partially redundant. */ 3432 if (!cant_insert && by_all) 3433 { 3434 edge succ; 3435 bool do_insertion = false; 3436 3437 /* Insert only if we can remove a later expression on a path 3438 that we want to optimize for speed. 3439 The phi node that we will be inserting in BLOCK is not free, 3440 and inserting it for the sake of !optimize_for_speed successor 3441 may cause regressions on the speed path. */ 3442 FOR_EACH_EDGE (succ, ei, block->succs) 3443 { 3444 if (bitmap_set_contains_value (PA_IN (succ->dest), val) 3445 || bitmap_set_contains_value (ANTIC_IN (succ->dest), val)) 3446 { 3447 if (optimize_edge_for_speed_p (succ)) 3448 do_insertion = true; 3449 } 3450 } 3451 3452 if (!do_insertion) 3453 { 3454 if (dump_file && (dump_flags & TDF_DETAILS)) 3455 { 3456 fprintf (dump_file, "Skipping partial partial redundancy " 3457 "for expression "); 3458 print_pre_expr (dump_file, expr); 3459 fprintf (dump_file, " (%04d), not (partially) anticipated " 3460 "on any to be optimized for speed edges\n", val); 3461 } 3462 } 3463 else if (dbg_cnt (treepre_insert)) 3464 { 3465 pre_stats.pa_insert++; 3466 if (dump_file && (dump_flags & TDF_DETAILS)) 3467 { 3468 fprintf (dump_file, "Found partial partial redundancy " 3469 "for expression "); 3470 print_pre_expr (dump_file, expr); 3471 fprintf (dump_file, " (%04d)\n", 3472 get_expr_value_id (expr)); 3473 } 3474 if (insert_into_preds_of_block (block, 3475 get_expression_id (expr), 3476 avail)) 3477 new_stuff = true; 3478 } 3479 } 3480 } 3481 } 3482 3483 exprs.release (); 3484 return new_stuff; 3485 } 3486 3487 /* Insert expressions in BLOCK to compute hoistable values up. 3488 Return TRUE if something was inserted, otherwise return FALSE. 3489 The caller has to make sure that BLOCK has at least two successors. */ 3490 3491 static bool 3492 do_hoist_insertion (basic_block block) 3493 { 3494 edge e; 3495 edge_iterator ei; 3496 bool new_stuff = false; 3497 unsigned i; 3498 gimple_stmt_iterator last; 3499 3500 /* At least two successors, or else... */ 3501 gcc_assert (EDGE_COUNT (block->succs) >= 2); 3502 3503 /* Check that all successors of BLOCK are dominated by block. 3504 We could use dominated_by_p() for this, but actually there is a much 3505 quicker check: any successor that is dominated by BLOCK can't have 3506 more than one predecessor edge. */ 3507 FOR_EACH_EDGE (e, ei, block->succs) 3508 if (! single_pred_p (e->dest)) 3509 return false; 3510 3511 /* Determine the insertion point. If we cannot safely insert before 3512 the last stmt if we'd have to, bail out. */ 3513 last = gsi_last_bb (block); 3514 if (!gsi_end_p (last) 3515 && !is_ctrl_stmt (gsi_stmt (last)) 3516 && stmt_ends_bb_p (gsi_stmt (last))) 3517 return false; 3518 3519 /* Compute the set of hoistable expressions from ANTIC_IN. First compute 3520 hoistable values. */ 3521 bitmap_set hoistable_set; 3522 3523 /* A hoistable value must be in ANTIC_IN(block) 3524 but not in AVAIL_OUT(BLOCK). */ 3525 bitmap_initialize (&hoistable_set.values, &grand_bitmap_obstack); 3526 bitmap_and_compl (&hoistable_set.values, 3527 &ANTIC_IN (block)->values, &AVAIL_OUT (block)->values); 3528 3529 /* Short-cut for a common case: hoistable_set is empty. */ 3530 if (bitmap_empty_p (&hoistable_set.values)) 3531 return false; 3532 3533 /* Compute which of the hoistable values is in AVAIL_OUT of 3534 at least one of the successors of BLOCK. */ 3535 bitmap_head availout_in_some; 3536 bitmap_initialize (&availout_in_some, &grand_bitmap_obstack); 3537 FOR_EACH_EDGE (e, ei, block->succs) 3538 /* Do not consider expressions solely because their availability 3539 on loop exits. They'd be ANTIC-IN throughout the whole loop 3540 and thus effectively hoisted across loops by combination of 3541 PRE and hoisting. */ 3542 if (! loop_exit_edge_p (block->loop_father, e)) 3543 bitmap_ior_and_into (&availout_in_some, &hoistable_set.values, 3544 &AVAIL_OUT (e->dest)->values); 3545 bitmap_clear (&hoistable_set.values); 3546 3547 /* Short-cut for a common case: availout_in_some is empty. */ 3548 if (bitmap_empty_p (&availout_in_some)) 3549 return false; 3550 3551 /* Hack hoitable_set in-place so we can use sorted_array_from_bitmap_set. */ 3552 hoistable_set.values = availout_in_some; 3553 hoistable_set.expressions = ANTIC_IN (block)->expressions; 3554 3555 /* Now finally construct the topological-ordered expression set. */ 3556 vec<pre_expr> exprs = sorted_array_from_bitmap_set (&hoistable_set); 3557 3558 bitmap_clear (&hoistable_set.values); 3559 3560 /* If there are candidate values for hoisting, insert expressions 3561 strategically to make the hoistable expressions fully redundant. */ 3562 pre_expr expr; 3563 FOR_EACH_VEC_ELT (exprs, i, expr) 3564 { 3565 /* While we try to sort expressions topologically above the 3566 sorting doesn't work out perfectly. Catch expressions we 3567 already inserted. */ 3568 unsigned int value_id = get_expr_value_id (expr); 3569 if (bitmap_set_contains_value (AVAIL_OUT (block), value_id)) 3570 { 3571 if (dump_file && (dump_flags & TDF_DETAILS)) 3572 { 3573 fprintf (dump_file, 3574 "Already inserted expression for "); 3575 print_pre_expr (dump_file, expr); 3576 fprintf (dump_file, " (%04d)\n", value_id); 3577 } 3578 continue; 3579 } 3580 3581 /* OK, we should hoist this value. Perform the transformation. */ 3582 pre_stats.hoist_insert++; 3583 if (dump_file && (dump_flags & TDF_DETAILS)) 3584 { 3585 fprintf (dump_file, 3586 "Inserting expression in block %d for code hoisting: ", 3587 block->index); 3588 print_pre_expr (dump_file, expr); 3589 fprintf (dump_file, " (%04d)\n", value_id); 3590 } 3591 3592 gimple_seq stmts = NULL; 3593 tree res = create_expression_by_pieces (block, expr, &stmts, 3594 get_expr_type (expr)); 3595 3596 /* Do not return true if expression creation ultimately 3597 did not insert any statements. */ 3598 if (gimple_seq_empty_p (stmts)) 3599 res = NULL_TREE; 3600 else 3601 { 3602 if (gsi_end_p (last) || is_ctrl_stmt (gsi_stmt (last))) 3603 gsi_insert_seq_before (&last, stmts, GSI_SAME_STMT); 3604 else 3605 gsi_insert_seq_after (&last, stmts, GSI_NEW_STMT); 3606 } 3607 3608 /* Make sure to not return true if expression creation ultimately 3609 failed but also make sure to insert any stmts produced as they 3610 are tracked in inserted_exprs. */ 3611 if (! res) 3612 continue; 3613 3614 new_stuff = true; 3615 } 3616 3617 exprs.release (); 3618 3619 return new_stuff; 3620 } 3621 3622 /* Do a dominator walk on the control flow graph, and insert computations 3623 of values as necessary for PRE and hoisting. */ 3624 3625 static bool 3626 insert_aux (basic_block block, bool do_pre, bool do_hoist) 3627 { 3628 basic_block son; 3629 bool new_stuff = false; 3630 3631 if (block) 3632 { 3633 basic_block dom; 3634 dom = get_immediate_dominator (CDI_DOMINATORS, block); 3635 if (dom) 3636 { 3637 unsigned i; 3638 bitmap_iterator bi; 3639 bitmap_set_t newset; 3640 3641 /* First, update the AVAIL_OUT set with anything we may have 3642 inserted higher up in the dominator tree. */ 3643 newset = NEW_SETS (dom); 3644 if (newset) 3645 { 3646 /* Note that we need to value_replace both NEW_SETS, and 3647 AVAIL_OUT. For both the case of NEW_SETS, the value may be 3648 represented by some non-simple expression here that we want 3649 to replace it with. */ 3650 FOR_EACH_EXPR_ID_IN_SET (newset, i, bi) 3651 { 3652 pre_expr expr = expression_for_id (i); 3653 bitmap_value_replace_in_set (NEW_SETS (block), expr); 3654 bitmap_value_replace_in_set (AVAIL_OUT (block), expr); 3655 } 3656 } 3657 3658 /* Insert expressions for partial redundancies. */ 3659 if (do_pre && !single_pred_p (block)) 3660 { 3661 new_stuff |= do_pre_regular_insertion (block, dom); 3662 if (do_partial_partial) 3663 new_stuff |= do_pre_partial_partial_insertion (block, dom); 3664 } 3665 3666 /* Insert expressions for hoisting. */ 3667 if (do_hoist && EDGE_COUNT (block->succs) >= 2) 3668 new_stuff |= do_hoist_insertion (block); 3669 } 3670 } 3671 for (son = first_dom_son (CDI_DOMINATORS, block); 3672 son; 3673 son = next_dom_son (CDI_DOMINATORS, son)) 3674 { 3675 new_stuff |= insert_aux (son, do_pre, do_hoist); 3676 } 3677 3678 return new_stuff; 3679 } 3680 3681 /* Perform insertion of partially redundant and hoistable values. */ 3682 3683 static void 3684 insert (void) 3685 { 3686 bool new_stuff = true; 3687 basic_block bb; 3688 int num_iterations = 0; 3689 3690 FOR_ALL_BB_FN (bb, cfun) 3691 NEW_SETS (bb) = bitmap_set_new (); 3692 3693 while (new_stuff) 3694 { 3695 num_iterations++; 3696 if (dump_file && dump_flags & TDF_DETAILS) 3697 fprintf (dump_file, "Starting insert iteration %d\n", num_iterations); 3698 new_stuff = insert_aux (ENTRY_BLOCK_PTR_FOR_FN (cfun), flag_tree_pre, 3699 flag_code_hoisting); 3700 3701 /* Clear the NEW sets before the next iteration. We have already 3702 fully propagated its contents. */ 3703 if (new_stuff) 3704 FOR_ALL_BB_FN (bb, cfun) 3705 bitmap_set_free (NEW_SETS (bb)); 3706 } 3707 statistics_histogram_event (cfun, "insert iterations", num_iterations); 3708 } 3709 3710 3711 /* Compute the AVAIL set for all basic blocks. 3712 3713 This function performs value numbering of the statements in each basic 3714 block. The AVAIL sets are built from information we glean while doing 3715 this value numbering, since the AVAIL sets contain only one entry per 3716 value. 3717 3718 AVAIL_IN[BLOCK] = AVAIL_OUT[dom(BLOCK)]. 3719 AVAIL_OUT[BLOCK] = AVAIL_IN[BLOCK] U PHI_GEN[BLOCK] U TMP_GEN[BLOCK]. */ 3720 3721 static void 3722 compute_avail (void) 3723 { 3724 3725 basic_block block, son; 3726 basic_block *worklist; 3727 size_t sp = 0; 3728 unsigned i; 3729 tree name; 3730 3731 /* We pretend that default definitions are defined in the entry block. 3732 This includes function arguments and the static chain decl. */ 3733 FOR_EACH_SSA_NAME (i, name, cfun) 3734 { 3735 pre_expr e; 3736 if (!SSA_NAME_IS_DEFAULT_DEF (name) 3737 || has_zero_uses (name) 3738 || virtual_operand_p (name)) 3739 continue; 3740 3741 e = get_or_alloc_expr_for_name (name); 3742 add_to_value (get_expr_value_id (e), e); 3743 bitmap_insert_into_set (TMP_GEN (ENTRY_BLOCK_PTR_FOR_FN (cfun)), e); 3744 bitmap_value_insert_into_set (AVAIL_OUT (ENTRY_BLOCK_PTR_FOR_FN (cfun)), 3745 e); 3746 } 3747 3748 if (dump_file && (dump_flags & TDF_DETAILS)) 3749 { 3750 print_bitmap_set (dump_file, TMP_GEN (ENTRY_BLOCK_PTR_FOR_FN (cfun)), 3751 "tmp_gen", ENTRY_BLOCK); 3752 print_bitmap_set (dump_file, AVAIL_OUT (ENTRY_BLOCK_PTR_FOR_FN (cfun)), 3753 "avail_out", ENTRY_BLOCK); 3754 } 3755 3756 /* Allocate the worklist. */ 3757 worklist = XNEWVEC (basic_block, n_basic_blocks_for_fn (cfun)); 3758 3759 /* Seed the algorithm by putting the dominator children of the entry 3760 block on the worklist. */ 3761 for (son = first_dom_son (CDI_DOMINATORS, ENTRY_BLOCK_PTR_FOR_FN (cfun)); 3762 son; 3763 son = next_dom_son (CDI_DOMINATORS, son)) 3764 worklist[sp++] = son; 3765 3766 BB_LIVE_VOP_ON_EXIT (ENTRY_BLOCK_PTR_FOR_FN (cfun)) 3767 = ssa_default_def (cfun, gimple_vop (cfun)); 3768 3769 /* Loop until the worklist is empty. */ 3770 while (sp) 3771 { 3772 gimple *stmt; 3773 basic_block dom; 3774 3775 /* Pick a block from the worklist. */ 3776 block = worklist[--sp]; 3777 3778 /* Initially, the set of available values in BLOCK is that of 3779 its immediate dominator. */ 3780 dom = get_immediate_dominator (CDI_DOMINATORS, block); 3781 if (dom) 3782 { 3783 bitmap_set_copy (AVAIL_OUT (block), AVAIL_OUT (dom)); 3784 BB_LIVE_VOP_ON_EXIT (block) = BB_LIVE_VOP_ON_EXIT (dom); 3785 } 3786 3787 /* Generate values for PHI nodes. */ 3788 for (gphi_iterator gsi = gsi_start_phis (block); !gsi_end_p (gsi); 3789 gsi_next (&gsi)) 3790 { 3791 tree result = gimple_phi_result (gsi.phi ()); 3792 3793 /* We have no need for virtual phis, as they don't represent 3794 actual computations. */ 3795 if (virtual_operand_p (result)) 3796 { 3797 BB_LIVE_VOP_ON_EXIT (block) = result; 3798 continue; 3799 } 3800 3801 pre_expr e = get_or_alloc_expr_for_name (result); 3802 add_to_value (get_expr_value_id (e), e); 3803 bitmap_value_insert_into_set (AVAIL_OUT (block), e); 3804 bitmap_insert_into_set (PHI_GEN (block), e); 3805 } 3806 3807 BB_MAY_NOTRETURN (block) = 0; 3808 3809 /* Now compute value numbers and populate value sets with all 3810 the expressions computed in BLOCK. */ 3811 for (gimple_stmt_iterator gsi = gsi_start_bb (block); !gsi_end_p (gsi); 3812 gsi_next (&gsi)) 3813 { 3814 ssa_op_iter iter; 3815 tree op; 3816 3817 stmt = gsi_stmt (gsi); 3818 3819 /* Cache whether the basic-block has any non-visible side-effect 3820 or control flow. 3821 If this isn't a call or it is the last stmt in the 3822 basic-block then the CFG represents things correctly. */ 3823 if (is_gimple_call (stmt) && !stmt_ends_bb_p (stmt)) 3824 { 3825 /* Non-looping const functions always return normally. 3826 Otherwise the call might not return or have side-effects 3827 that forbids hoisting possibly trapping expressions 3828 before it. */ 3829 int flags = gimple_call_flags (stmt); 3830 if (!(flags & ECF_CONST) 3831 || (flags & ECF_LOOPING_CONST_OR_PURE)) 3832 BB_MAY_NOTRETURN (block) = 1; 3833 } 3834 3835 FOR_EACH_SSA_TREE_OPERAND (op, stmt, iter, SSA_OP_DEF) 3836 { 3837 pre_expr e = get_or_alloc_expr_for_name (op); 3838 3839 add_to_value (get_expr_value_id (e), e); 3840 bitmap_insert_into_set (TMP_GEN (block), e); 3841 bitmap_value_insert_into_set (AVAIL_OUT (block), e); 3842 } 3843 3844 if (gimple_vdef (stmt)) 3845 BB_LIVE_VOP_ON_EXIT (block) = gimple_vdef (stmt); 3846 3847 if (gimple_has_side_effects (stmt) 3848 || stmt_could_throw_p (stmt) 3849 || is_gimple_debug (stmt)) 3850 continue; 3851 3852 FOR_EACH_SSA_TREE_OPERAND (op, stmt, iter, SSA_OP_USE) 3853 { 3854 if (ssa_undefined_value_p (op)) 3855 continue; 3856 pre_expr e = get_or_alloc_expr_for_name (op); 3857 bitmap_value_insert_into_set (EXP_GEN (block), e); 3858 } 3859 3860 switch (gimple_code (stmt)) 3861 { 3862 case GIMPLE_RETURN: 3863 continue; 3864 3865 case GIMPLE_CALL: 3866 { 3867 vn_reference_t ref; 3868 vn_reference_s ref1; 3869 pre_expr result = NULL; 3870 3871 /* We can value number only calls to real functions. */ 3872 if (gimple_call_internal_p (stmt)) 3873 continue; 3874 3875 vn_reference_lookup_call (as_a <gcall *> (stmt), &ref, &ref1); 3876 if (!ref) 3877 continue; 3878 3879 /* If the value of the call is not invalidated in 3880 this block until it is computed, add the expression 3881 to EXP_GEN. */ 3882 if (!gimple_vuse (stmt) 3883 || gimple_code 3884 (SSA_NAME_DEF_STMT (gimple_vuse (stmt))) == GIMPLE_PHI 3885 || gimple_bb (SSA_NAME_DEF_STMT 3886 (gimple_vuse (stmt))) != block) 3887 { 3888 result = pre_expr_pool.allocate (); 3889 result->kind = REFERENCE; 3890 result->id = 0; 3891 PRE_EXPR_REFERENCE (result) = ref; 3892 3893 get_or_alloc_expression_id (result); 3894 add_to_value (get_expr_value_id (result), result); 3895 bitmap_value_insert_into_set (EXP_GEN (block), result); 3896 } 3897 continue; 3898 } 3899 3900 case GIMPLE_ASSIGN: 3901 { 3902 pre_expr result = NULL; 3903 switch (vn_get_stmt_kind (stmt)) 3904 { 3905 case VN_NARY: 3906 { 3907 enum tree_code code = gimple_assign_rhs_code (stmt); 3908 vn_nary_op_t nary; 3909 3910 /* COND_EXPR and VEC_COND_EXPR are awkward in 3911 that they contain an embedded complex expression. 3912 Don't even try to shove those through PRE. */ 3913 if (code == COND_EXPR 3914 || code == VEC_COND_EXPR) 3915 continue; 3916 3917 vn_nary_op_lookup_stmt (stmt, &nary); 3918 if (!nary) 3919 continue; 3920 3921 /* If the NARY traps and there was a preceding 3922 point in the block that might not return avoid 3923 adding the nary to EXP_GEN. */ 3924 if (BB_MAY_NOTRETURN (block) 3925 && vn_nary_may_trap (nary)) 3926 continue; 3927 3928 result = pre_expr_pool.allocate (); 3929 result->kind = NARY; 3930 result->id = 0; 3931 PRE_EXPR_NARY (result) = nary; 3932 break; 3933 } 3934 3935 case VN_REFERENCE: 3936 { 3937 tree rhs1 = gimple_assign_rhs1 (stmt); 3938 alias_set_type set = get_alias_set (rhs1); 3939 vec<vn_reference_op_s> operands 3940 = vn_reference_operands_for_lookup (rhs1); 3941 vn_reference_t ref; 3942 vn_reference_lookup_pieces (gimple_vuse (stmt), set, 3943 TREE_TYPE (rhs1), 3944 operands, &ref, VN_WALK); 3945 if (!ref) 3946 { 3947 operands.release (); 3948 continue; 3949 } 3950 3951 /* If the REFERENCE traps and there was a preceding 3952 point in the block that might not return avoid 3953 adding the reference to EXP_GEN. */ 3954 if (BB_MAY_NOTRETURN (block) 3955 && vn_reference_may_trap (ref)) 3956 continue; 3957 3958 /* If the value of the reference is not invalidated in 3959 this block until it is computed, add the expression 3960 to EXP_GEN. */ 3961 if (gimple_vuse (stmt)) 3962 { 3963 gimple *def_stmt; 3964 bool ok = true; 3965 def_stmt = SSA_NAME_DEF_STMT (gimple_vuse (stmt)); 3966 while (!gimple_nop_p (def_stmt) 3967 && gimple_code (def_stmt) != GIMPLE_PHI 3968 && gimple_bb (def_stmt) == block) 3969 { 3970 if (stmt_may_clobber_ref_p 3971 (def_stmt, gimple_assign_rhs1 (stmt))) 3972 { 3973 ok = false; 3974 break; 3975 } 3976 def_stmt 3977 = SSA_NAME_DEF_STMT (gimple_vuse (def_stmt)); 3978 } 3979 if (!ok) 3980 { 3981 operands.release (); 3982 continue; 3983 } 3984 } 3985 3986 /* If the load was value-numbered to another 3987 load make sure we do not use its expression 3988 for insertion if it wouldn't be a valid 3989 replacement. */ 3990 /* At the momemt we have a testcase 3991 for hoist insertion of aligned vs. misaligned 3992 variants in gcc.dg/torture/pr65270-1.c thus 3993 with just alignment to be considered we can 3994 simply replace the expression in the hashtable 3995 with the most conservative one. */ 3996 vn_reference_op_t ref1 = &ref->operands.last (); 3997 while (ref1->opcode != TARGET_MEM_REF 3998 && ref1->opcode != MEM_REF 3999 && ref1 != &ref->operands[0]) 4000 --ref1; 4001 vn_reference_op_t ref2 = &operands.last (); 4002 while (ref2->opcode != TARGET_MEM_REF 4003 && ref2->opcode != MEM_REF 4004 && ref2 != &operands[0]) 4005 --ref2; 4006 if ((ref1->opcode == TARGET_MEM_REF 4007 || ref1->opcode == MEM_REF) 4008 && (TYPE_ALIGN (ref1->type) 4009 > TYPE_ALIGN (ref2->type))) 4010 ref1->type 4011 = build_aligned_type (ref1->type, 4012 TYPE_ALIGN (ref2->type)); 4013 /* TBAA behavior is an obvious part so make sure 4014 that the hashtable one covers this as well 4015 by adjusting the ref alias set and its base. */ 4016 if (ref->set == set 4017 || alias_set_subset_of (set, ref->set)) 4018 ; 4019 else if (alias_set_subset_of (ref->set, set)) 4020 { 4021 ref->set = set; 4022 if (ref1->opcode == MEM_REF) 4023 ref1->op0 = wide_int_to_tree (TREE_TYPE (ref2->op0), 4024 ref1->op0); 4025 else 4026 ref1->op2 = wide_int_to_tree (TREE_TYPE (ref2->op2), 4027 ref1->op2); 4028 } 4029 else 4030 { 4031 ref->set = 0; 4032 if (ref1->opcode == MEM_REF) 4033 ref1->op0 = wide_int_to_tree (ptr_type_node, 4034 ref1->op0); 4035 else 4036 ref1->op2 = wide_int_to_tree (ptr_type_node, 4037 ref1->op2); 4038 } 4039 operands.release (); 4040 4041 result = pre_expr_pool.allocate (); 4042 result->kind = REFERENCE; 4043 result->id = 0; 4044 PRE_EXPR_REFERENCE (result) = ref; 4045 break; 4046 } 4047 4048 default: 4049 continue; 4050 } 4051 4052 get_or_alloc_expression_id (result); 4053 add_to_value (get_expr_value_id (result), result); 4054 bitmap_value_insert_into_set (EXP_GEN (block), result); 4055 continue; 4056 } 4057 default: 4058 break; 4059 } 4060 } 4061 4062 if (dump_file && (dump_flags & TDF_DETAILS)) 4063 { 4064 print_bitmap_set (dump_file, EXP_GEN (block), 4065 "exp_gen", block->index); 4066 print_bitmap_set (dump_file, PHI_GEN (block), 4067 "phi_gen", block->index); 4068 print_bitmap_set (dump_file, TMP_GEN (block), 4069 "tmp_gen", block->index); 4070 print_bitmap_set (dump_file, AVAIL_OUT (block), 4071 "avail_out", block->index); 4072 } 4073 4074 /* Put the dominator children of BLOCK on the worklist of blocks 4075 to compute available sets for. */ 4076 for (son = first_dom_son (CDI_DOMINATORS, block); 4077 son; 4078 son = next_dom_son (CDI_DOMINATORS, son)) 4079 worklist[sp++] = son; 4080 } 4081 4082 free (worklist); 4083 } 4084 4085 4086 /* Local state for the eliminate domwalk. */ 4087 static vec<gimple *> el_to_remove; 4088 static vec<gimple *> el_to_fixup; 4089 static unsigned int el_todo; 4090 static vec<tree> el_avail; 4091 static vec<tree> el_avail_stack; 4092 4093 /* Return a leader for OP that is available at the current point of the 4094 eliminate domwalk. */ 4095 4096 static tree 4097 eliminate_avail (tree op) 4098 { 4099 tree valnum = VN_INFO (op)->valnum; 4100 if (TREE_CODE (valnum) == SSA_NAME) 4101 { 4102 if (SSA_NAME_IS_DEFAULT_DEF (valnum)) 4103 return valnum; 4104 if (el_avail.length () > SSA_NAME_VERSION (valnum)) 4105 return el_avail[SSA_NAME_VERSION (valnum)]; 4106 } 4107 else if (is_gimple_min_invariant (valnum)) 4108 return valnum; 4109 return NULL_TREE; 4110 } 4111 4112 /* At the current point of the eliminate domwalk make OP available. */ 4113 4114 static void 4115 eliminate_push_avail (tree op) 4116 { 4117 tree valnum = VN_INFO (op)->valnum; 4118 if (TREE_CODE (valnum) == SSA_NAME) 4119 { 4120 if (el_avail.length () <= SSA_NAME_VERSION (valnum)) 4121 el_avail.safe_grow_cleared (SSA_NAME_VERSION (valnum) + 1); 4122 tree pushop = op; 4123 if (el_avail[SSA_NAME_VERSION (valnum)]) 4124 pushop = el_avail[SSA_NAME_VERSION (valnum)]; 4125 el_avail_stack.safe_push (pushop); 4126 el_avail[SSA_NAME_VERSION (valnum)] = op; 4127 } 4128 } 4129 4130 /* Insert the expression recorded by SCCVN for VAL at *GSI. Returns 4131 the leader for the expression if insertion was successful. */ 4132 4133 static tree 4134 eliminate_insert (gimple_stmt_iterator *gsi, tree val) 4135 { 4136 /* We can insert a sequence with a single assignment only. */ 4137 gimple_seq stmts = VN_INFO (val)->expr; 4138 if (!gimple_seq_singleton_p (stmts)) 4139 return NULL_TREE; 4140 gassign *stmt = dyn_cast <gassign *> (gimple_seq_first_stmt (stmts)); 4141 if (!stmt 4142 || (!CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (stmt)) 4143 && gimple_assign_rhs_code (stmt) != VIEW_CONVERT_EXPR 4144 && gimple_assign_rhs_code (stmt) != BIT_FIELD_REF 4145 && (gimple_assign_rhs_code (stmt) != BIT_AND_EXPR 4146 || TREE_CODE (gimple_assign_rhs2 (stmt)) != INTEGER_CST))) 4147 return NULL_TREE; 4148 4149 tree op = gimple_assign_rhs1 (stmt); 4150 if (gimple_assign_rhs_code (stmt) == VIEW_CONVERT_EXPR 4151 || gimple_assign_rhs_code (stmt) == BIT_FIELD_REF) 4152 op = TREE_OPERAND (op, 0); 4153 tree leader = TREE_CODE (op) == SSA_NAME ? eliminate_avail (op) : op; 4154 if (!leader) 4155 return NULL_TREE; 4156 4157 tree res; 4158 stmts = NULL; 4159 if (gimple_assign_rhs_code (stmt) == BIT_FIELD_REF) 4160 res = gimple_build (&stmts, BIT_FIELD_REF, 4161 TREE_TYPE (val), leader, 4162 TREE_OPERAND (gimple_assign_rhs1 (stmt), 1), 4163 TREE_OPERAND (gimple_assign_rhs1 (stmt), 2)); 4164 else if (gimple_assign_rhs_code (stmt) == BIT_AND_EXPR) 4165 res = gimple_build (&stmts, BIT_AND_EXPR, 4166 TREE_TYPE (val), leader, gimple_assign_rhs2 (stmt)); 4167 else 4168 res = gimple_build (&stmts, gimple_assign_rhs_code (stmt), 4169 TREE_TYPE (val), leader); 4170 if (TREE_CODE (res) != SSA_NAME 4171 || SSA_NAME_IS_DEFAULT_DEF (res) 4172 || gimple_bb (SSA_NAME_DEF_STMT (res))) 4173 { 4174 gimple_seq_discard (stmts); 4175 4176 /* During propagation we have to treat SSA info conservatively 4177 and thus we can end up simplifying the inserted expression 4178 at elimination time to sth not defined in stmts. */ 4179 /* But then this is a redundancy we failed to detect. Which means 4180 res now has two values. That doesn't play well with how 4181 we track availability here, so give up. */ 4182 if (dump_file && (dump_flags & TDF_DETAILS)) 4183 { 4184 if (TREE_CODE (res) == SSA_NAME) 4185 res = eliminate_avail (res); 4186 if (res) 4187 { 4188 fprintf (dump_file, "Failed to insert expression for value "); 4189 print_generic_expr (dump_file, val, 0); 4190 fprintf (dump_file, " which is really fully redundant to "); 4191 print_generic_expr (dump_file, res, 0); 4192 fprintf (dump_file, "\n"); 4193 } 4194 } 4195 4196 return NULL_TREE; 4197 } 4198 else 4199 { 4200 gsi_insert_seq_before (gsi, stmts, GSI_SAME_STMT); 4201 VN_INFO_GET (res)->valnum = val; 4202 4203 if (TREE_CODE (leader) == SSA_NAME) 4204 gimple_set_plf (SSA_NAME_DEF_STMT (leader), NECESSARY, true); 4205 } 4206 4207 pre_stats.insertions++; 4208 if (dump_file && (dump_flags & TDF_DETAILS)) 4209 { 4210 fprintf (dump_file, "Inserted "); 4211 print_gimple_stmt (dump_file, SSA_NAME_DEF_STMT (res), 0, 0); 4212 } 4213 4214 return res; 4215 } 4216 4217 class eliminate_dom_walker : public dom_walker 4218 { 4219 public: 4220 eliminate_dom_walker (cdi_direction direction, bool do_pre_) 4221 : dom_walker (direction), do_pre (do_pre_) {} 4222 4223 virtual edge before_dom_children (basic_block); 4224 virtual void after_dom_children (basic_block); 4225 4226 bool do_pre; 4227 }; 4228 4229 /* Perform elimination for the basic-block B during the domwalk. */ 4230 4231 edge 4232 eliminate_dom_walker::before_dom_children (basic_block b) 4233 { 4234 /* Mark new bb. */ 4235 el_avail_stack.safe_push (NULL_TREE); 4236 4237 /* ??? If we do nothing for unreachable blocks then this will confuse 4238 tailmerging. Eventually we can reduce its reliance on SCCVN now 4239 that we fully copy/constant-propagate (most) things. */ 4240 4241 for (gphi_iterator gsi = gsi_start_phis (b); !gsi_end_p (gsi);) 4242 { 4243 gphi *phi = gsi.phi (); 4244 tree res = PHI_RESULT (phi); 4245 4246 if (virtual_operand_p (res)) 4247 { 4248 gsi_next (&gsi); 4249 continue; 4250 } 4251 4252 tree sprime = eliminate_avail (res); 4253 if (sprime 4254 && sprime != res) 4255 { 4256 if (dump_file && (dump_flags & TDF_DETAILS)) 4257 { 4258 fprintf (dump_file, "Replaced redundant PHI node defining "); 4259 print_generic_expr (dump_file, res, 0); 4260 fprintf (dump_file, " with "); 4261 print_generic_expr (dump_file, sprime, 0); 4262 fprintf (dump_file, "\n"); 4263 } 4264 4265 /* If we inserted this PHI node ourself, it's not an elimination. */ 4266 if (inserted_exprs 4267 && bitmap_bit_p (inserted_exprs, SSA_NAME_VERSION (res))) 4268 pre_stats.phis--; 4269 else 4270 pre_stats.eliminations++; 4271 4272 /* If we will propagate into all uses don't bother to do 4273 anything. */ 4274 if (may_propagate_copy (res, sprime)) 4275 { 4276 /* Mark the PHI for removal. */ 4277 el_to_remove.safe_push (phi); 4278 gsi_next (&gsi); 4279 continue; 4280 } 4281 4282 remove_phi_node (&gsi, false); 4283 4284 if (inserted_exprs 4285 && !bitmap_bit_p (inserted_exprs, SSA_NAME_VERSION (res)) 4286 && TREE_CODE (sprime) == SSA_NAME) 4287 gimple_set_plf (SSA_NAME_DEF_STMT (sprime), NECESSARY, true); 4288 4289 if (!useless_type_conversion_p (TREE_TYPE (res), TREE_TYPE (sprime))) 4290 sprime = fold_convert (TREE_TYPE (res), sprime); 4291 gimple *stmt = gimple_build_assign (res, sprime); 4292 /* ??? It cannot yet be necessary (DOM walk). */ 4293 gimple_set_plf (stmt, NECESSARY, gimple_plf (phi, NECESSARY)); 4294 4295 gimple_stmt_iterator gsi2 = gsi_after_labels (b); 4296 gsi_insert_before (&gsi2, stmt, GSI_NEW_STMT); 4297 continue; 4298 } 4299 4300 eliminate_push_avail (res); 4301 gsi_next (&gsi); 4302 } 4303 4304 for (gimple_stmt_iterator gsi = gsi_start_bb (b); 4305 !gsi_end_p (gsi); 4306 gsi_next (&gsi)) 4307 { 4308 tree sprime = NULL_TREE; 4309 gimple *stmt = gsi_stmt (gsi); 4310 tree lhs = gimple_get_lhs (stmt); 4311 if (lhs && TREE_CODE (lhs) == SSA_NAME 4312 && !gimple_has_volatile_ops (stmt) 4313 /* See PR43491. Do not replace a global register variable when 4314 it is a the RHS of an assignment. Do replace local register 4315 variables since gcc does not guarantee a local variable will 4316 be allocated in register. 4317 ??? The fix isn't effective here. This should instead 4318 be ensured by not value-numbering them the same but treating 4319 them like volatiles? */ 4320 && !(gimple_assign_single_p (stmt) 4321 && (TREE_CODE (gimple_assign_rhs1 (stmt)) == VAR_DECL 4322 && DECL_HARD_REGISTER (gimple_assign_rhs1 (stmt)) 4323 && is_global_var (gimple_assign_rhs1 (stmt))))) 4324 { 4325 sprime = eliminate_avail (lhs); 4326 if (!sprime) 4327 { 4328 /* If there is no existing usable leader but SCCVN thinks 4329 it has an expression it wants to use as replacement, 4330 insert that. */ 4331 tree val = VN_INFO (lhs)->valnum; 4332 if (val != VN_TOP 4333 && TREE_CODE (val) == SSA_NAME 4334 && VN_INFO (val)->needs_insertion 4335 && VN_INFO (val)->expr != NULL 4336 && (sprime = eliminate_insert (&gsi, val)) != NULL_TREE) 4337 eliminate_push_avail (sprime); 4338 } 4339 4340 /* If this now constitutes a copy duplicate points-to 4341 and range info appropriately. This is especially 4342 important for inserted code. See tree-ssa-copy.c 4343 for similar code. */ 4344 if (sprime 4345 && TREE_CODE (sprime) == SSA_NAME) 4346 { 4347 basic_block sprime_b = gimple_bb (SSA_NAME_DEF_STMT (sprime)); 4348 if (POINTER_TYPE_P (TREE_TYPE (lhs)) 4349 && VN_INFO_PTR_INFO (lhs) 4350 && ! VN_INFO_PTR_INFO (sprime)) 4351 { 4352 duplicate_ssa_name_ptr_info (sprime, 4353 VN_INFO_PTR_INFO (lhs)); 4354 if (b != sprime_b) 4355 mark_ptr_info_alignment_unknown 4356 (SSA_NAME_PTR_INFO (sprime)); 4357 } 4358 else if (INTEGRAL_TYPE_P (TREE_TYPE (lhs)) 4359 && VN_INFO_RANGE_INFO (lhs) 4360 && ! VN_INFO_RANGE_INFO (sprime) 4361 && b == sprime_b) 4362 duplicate_ssa_name_range_info (sprime, 4363 VN_INFO_RANGE_TYPE (lhs), 4364 VN_INFO_RANGE_INFO (lhs)); 4365 } 4366 4367 /* Inhibit the use of an inserted PHI on a loop header when 4368 the address of the memory reference is a simple induction 4369 variable. In other cases the vectorizer won't do anything 4370 anyway (either it's loop invariant or a complicated 4371 expression). */ 4372 if (sprime 4373 && TREE_CODE (sprime) == SSA_NAME 4374 && do_pre 4375 && (flag_tree_loop_vectorize || flag_tree_parallelize_loops > 1) 4376 && loop_outer (b->loop_father) 4377 && has_zero_uses (sprime) 4378 && bitmap_bit_p (inserted_exprs, SSA_NAME_VERSION (sprime)) 4379 && gimple_assign_load_p (stmt)) 4380 { 4381 gimple *def_stmt = SSA_NAME_DEF_STMT (sprime); 4382 basic_block def_bb = gimple_bb (def_stmt); 4383 if (gimple_code (def_stmt) == GIMPLE_PHI 4384 && def_bb->loop_father->header == def_bb) 4385 { 4386 loop_p loop = def_bb->loop_father; 4387 ssa_op_iter iter; 4388 tree op; 4389 bool found = false; 4390 FOR_EACH_SSA_TREE_OPERAND (op, stmt, iter, SSA_OP_USE) 4391 { 4392 affine_iv iv; 4393 def_bb = gimple_bb (SSA_NAME_DEF_STMT (op)); 4394 if (def_bb 4395 && flow_bb_inside_loop_p (loop, def_bb) 4396 && simple_iv (loop, loop, op, &iv, true)) 4397 { 4398 found = true; 4399 break; 4400 } 4401 } 4402 if (found) 4403 { 4404 if (dump_file && (dump_flags & TDF_DETAILS)) 4405 { 4406 fprintf (dump_file, "Not replacing "); 4407 print_gimple_expr (dump_file, stmt, 0, 0); 4408 fprintf (dump_file, " with "); 4409 print_generic_expr (dump_file, sprime, 0); 4410 fprintf (dump_file, " which would add a loop" 4411 " carried dependence to loop %d\n", 4412 loop->num); 4413 } 4414 /* Don't keep sprime available. */ 4415 sprime = NULL_TREE; 4416 } 4417 } 4418 } 4419 4420 if (sprime) 4421 { 4422 /* If we can propagate the value computed for LHS into 4423 all uses don't bother doing anything with this stmt. */ 4424 if (may_propagate_copy (lhs, sprime)) 4425 { 4426 /* Mark it for removal. */ 4427 el_to_remove.safe_push (stmt); 4428 4429 /* ??? Don't count copy/constant propagations. */ 4430 if (gimple_assign_single_p (stmt) 4431 && (TREE_CODE (gimple_assign_rhs1 (stmt)) == SSA_NAME 4432 || gimple_assign_rhs1 (stmt) == sprime)) 4433 continue; 4434 4435 if (dump_file && (dump_flags & TDF_DETAILS)) 4436 { 4437 fprintf (dump_file, "Replaced "); 4438 print_gimple_expr (dump_file, stmt, 0, 0); 4439 fprintf (dump_file, " with "); 4440 print_generic_expr (dump_file, sprime, 0); 4441 fprintf (dump_file, " in all uses of "); 4442 print_gimple_stmt (dump_file, stmt, 0, 0); 4443 } 4444 4445 pre_stats.eliminations++; 4446 continue; 4447 } 4448 4449 /* If this is an assignment from our leader (which 4450 happens in the case the value-number is a constant) 4451 then there is nothing to do. */ 4452 if (gimple_assign_single_p (stmt) 4453 && sprime == gimple_assign_rhs1 (stmt)) 4454 continue; 4455 4456 /* Else replace its RHS. */ 4457 bool can_make_abnormal_goto 4458 = is_gimple_call (stmt) 4459 && stmt_can_make_abnormal_goto (stmt); 4460 4461 if (dump_file && (dump_flags & TDF_DETAILS)) 4462 { 4463 fprintf (dump_file, "Replaced "); 4464 print_gimple_expr (dump_file, stmt, 0, 0); 4465 fprintf (dump_file, " with "); 4466 print_generic_expr (dump_file, sprime, 0); 4467 fprintf (dump_file, " in "); 4468 print_gimple_stmt (dump_file, stmt, 0, 0); 4469 } 4470 4471 if (TREE_CODE (sprime) == SSA_NAME) 4472 gimple_set_plf (SSA_NAME_DEF_STMT (sprime), 4473 NECESSARY, true); 4474 4475 pre_stats.eliminations++; 4476 gimple *orig_stmt = stmt; 4477 if (!useless_type_conversion_p (TREE_TYPE (lhs), 4478 TREE_TYPE (sprime))) 4479 sprime = fold_convert (TREE_TYPE (lhs), sprime); 4480 tree vdef = gimple_vdef (stmt); 4481 tree vuse = gimple_vuse (stmt); 4482 propagate_tree_value_into_stmt (&gsi, sprime); 4483 stmt = gsi_stmt (gsi); 4484 update_stmt (stmt); 4485 if (vdef != gimple_vdef (stmt)) 4486 VN_INFO (vdef)->valnum = vuse; 4487 4488 /* If we removed EH side-effects from the statement, clean 4489 its EH information. */ 4490 if (maybe_clean_or_replace_eh_stmt (orig_stmt, stmt)) 4491 { 4492 bitmap_set_bit (need_eh_cleanup, 4493 gimple_bb (stmt)->index); 4494 if (dump_file && (dump_flags & TDF_DETAILS)) 4495 fprintf (dump_file, " Removed EH side-effects.\n"); 4496 } 4497 4498 /* Likewise for AB side-effects. */ 4499 if (can_make_abnormal_goto 4500 && !stmt_can_make_abnormal_goto (stmt)) 4501 { 4502 bitmap_set_bit (need_ab_cleanup, 4503 gimple_bb (stmt)->index); 4504 if (dump_file && (dump_flags & TDF_DETAILS)) 4505 fprintf (dump_file, " Removed AB side-effects.\n"); 4506 } 4507 4508 continue; 4509 } 4510 } 4511 4512 /* If the statement is a scalar store, see if the expression 4513 has the same value number as its rhs. If so, the store is 4514 dead. */ 4515 if (gimple_assign_single_p (stmt) 4516 && !gimple_has_volatile_ops (stmt) 4517 && !is_gimple_reg (gimple_assign_lhs (stmt)) 4518 && (TREE_CODE (gimple_assign_rhs1 (stmt)) == SSA_NAME 4519 || is_gimple_min_invariant (gimple_assign_rhs1 (stmt)))) 4520 { 4521 tree val; 4522 tree rhs = gimple_assign_rhs1 (stmt); 4523 vn_reference_t vnresult; 4524 val = vn_reference_lookup (lhs, gimple_vuse (stmt), VN_WALKREWRITE, 4525 &vnresult, false); 4526 if (TREE_CODE (rhs) == SSA_NAME) 4527 rhs = VN_INFO (rhs)->valnum; 4528 if (val 4529 && operand_equal_p (val, rhs, 0)) 4530 { 4531 /* We can only remove the later store if the former aliases 4532 at least all accesses the later one does or if the store 4533 was to readonly memory storing the same value. */ 4534 alias_set_type set = get_alias_set (lhs); 4535 if (! vnresult 4536 || vnresult->set == set 4537 || alias_set_subset_of (set, vnresult->set)) 4538 { 4539 if (dump_file && (dump_flags & TDF_DETAILS)) 4540 { 4541 fprintf (dump_file, "Deleted redundant store "); 4542 print_gimple_stmt (dump_file, stmt, 0, 0); 4543 } 4544 4545 /* Queue stmt for removal. */ 4546 el_to_remove.safe_push (stmt); 4547 continue; 4548 } 4549 } 4550 } 4551 4552 /* If this is a control statement value numbering left edges 4553 unexecuted on force the condition in a way consistent with 4554 that. */ 4555 if (gcond *cond = dyn_cast <gcond *> (stmt)) 4556 { 4557 if ((EDGE_SUCC (b, 0)->flags & EDGE_EXECUTABLE) 4558 ^ (EDGE_SUCC (b, 1)->flags & EDGE_EXECUTABLE)) 4559 { 4560 if (dump_file && (dump_flags & TDF_DETAILS)) 4561 { 4562 fprintf (dump_file, "Removing unexecutable edge from "); 4563 print_gimple_stmt (dump_file, stmt, 0, 0); 4564 } 4565 if (((EDGE_SUCC (b, 0)->flags & EDGE_TRUE_VALUE) != 0) 4566 == ((EDGE_SUCC (b, 0)->flags & EDGE_EXECUTABLE) != 0)) 4567 gimple_cond_make_true (cond); 4568 else 4569 gimple_cond_make_false (cond); 4570 update_stmt (cond); 4571 el_todo |= TODO_cleanup_cfg; 4572 continue; 4573 } 4574 } 4575 4576 bool can_make_abnormal_goto = stmt_can_make_abnormal_goto (stmt); 4577 bool was_noreturn = (is_gimple_call (stmt) 4578 && gimple_call_noreturn_p (stmt)); 4579 tree vdef = gimple_vdef (stmt); 4580 tree vuse = gimple_vuse (stmt); 4581 4582 /* If we didn't replace the whole stmt (or propagate the result 4583 into all uses), replace all uses on this stmt with their 4584 leaders. */ 4585 bool modified = false; 4586 use_operand_p use_p; 4587 ssa_op_iter iter; 4588 FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, SSA_OP_USE) 4589 { 4590 tree use = USE_FROM_PTR (use_p); 4591 /* ??? The call code above leaves stmt operands un-updated. */ 4592 if (TREE_CODE (use) != SSA_NAME) 4593 continue; 4594 tree sprime = eliminate_avail (use); 4595 if (sprime && sprime != use 4596 && may_propagate_copy (use, sprime) 4597 /* We substitute into debug stmts to avoid excessive 4598 debug temporaries created by removed stmts, but we need 4599 to avoid doing so for inserted sprimes as we never want 4600 to create debug temporaries for them. */ 4601 && (!inserted_exprs 4602 || TREE_CODE (sprime) != SSA_NAME 4603 || !is_gimple_debug (stmt) 4604 || !bitmap_bit_p (inserted_exprs, SSA_NAME_VERSION (sprime)))) 4605 { 4606 propagate_value (use_p, sprime); 4607 modified = true; 4608 if (TREE_CODE (sprime) == SSA_NAME 4609 && !is_gimple_debug (stmt)) 4610 gimple_set_plf (SSA_NAME_DEF_STMT (sprime), 4611 NECESSARY, true); 4612 } 4613 } 4614 4615 /* Fold the stmt if modified, this canonicalizes MEM_REFs we propagated 4616 into which is a requirement for the IPA devirt machinery. */ 4617 gimple *old_stmt = stmt; 4618 if (modified) 4619 { 4620 /* If a formerly non-invariant ADDR_EXPR is turned into an 4621 invariant one it was on a separate stmt. */ 4622 if (gimple_assign_single_p (stmt) 4623 && TREE_CODE (gimple_assign_rhs1 (stmt)) == ADDR_EXPR) 4624 recompute_tree_invariant_for_addr_expr (gimple_assign_rhs1 (stmt)); 4625 if (is_gimple_call (stmt)) 4626 { 4627 /* ??? Only fold calls inplace for now, this may create new 4628 SSA names which in turn will confuse free_scc_vn SSA name 4629 release code. */ 4630 fold_stmt_inplace (&gsi); 4631 } 4632 else 4633 { 4634 fold_stmt (&gsi); 4635 stmt = gsi_stmt (gsi); 4636 } 4637 } 4638 4639 /* Visit indirect calls and turn them into direct calls if 4640 possible using the devirtualization machinery. Do this before 4641 checking for required EH/abnormal/noreturn cleanup as devird 4642 may expose more of those. */ 4643 if (gcall *call_stmt = dyn_cast <gcall *> (stmt)) 4644 { 4645 tree fn = gimple_call_fn (call_stmt); 4646 if (fn 4647 && flag_devirtualize 4648 && virtual_method_call_p (fn)) 4649 { 4650 tree otr_type = obj_type_ref_class (fn); 4651 unsigned HOST_WIDE_INT otr_tok 4652 = tree_to_uhwi (OBJ_TYPE_REF_TOKEN (fn)); 4653 tree instance; 4654 ipa_polymorphic_call_context context (current_function_decl, 4655 fn, stmt, &instance); 4656 context.get_dynamic_type (instance, OBJ_TYPE_REF_OBJECT (fn), 4657 otr_type, stmt); 4658 bool final; 4659 vec <cgraph_node *> targets 4660 = possible_polymorphic_call_targets (obj_type_ref_class (fn), 4661 otr_tok, context, &final); 4662 if (dump_file) 4663 dump_possible_polymorphic_call_targets (dump_file, 4664 obj_type_ref_class (fn), 4665 otr_tok, context); 4666 if (final && targets.length () <= 1 && dbg_cnt (devirt)) 4667 { 4668 tree fn; 4669 if (targets.length () == 1) 4670 fn = targets[0]->decl; 4671 else 4672 fn = builtin_decl_implicit (BUILT_IN_UNREACHABLE); 4673 if (dump_enabled_p ()) 4674 { 4675 location_t loc = gimple_location (stmt); 4676 dump_printf_loc (MSG_OPTIMIZED_LOCATIONS, loc, 4677 "converting indirect call to " 4678 "function %s\n", 4679 lang_hooks.decl_printable_name (fn, 2)); 4680 } 4681 gimple_call_set_fndecl (call_stmt, fn); 4682 /* If changing the call to __builtin_unreachable 4683 or similar noreturn function, adjust gimple_call_fntype 4684 too. */ 4685 if (gimple_call_noreturn_p (call_stmt) 4686 && VOID_TYPE_P (TREE_TYPE (TREE_TYPE (fn))) 4687 && TYPE_ARG_TYPES (TREE_TYPE (fn)) 4688 && (TREE_VALUE (TYPE_ARG_TYPES (TREE_TYPE (fn))) 4689 == void_type_node)) 4690 gimple_call_set_fntype (call_stmt, TREE_TYPE (fn)); 4691 maybe_remove_unused_call_args (cfun, call_stmt); 4692 modified = true; 4693 } 4694 } 4695 } 4696 4697 if (modified) 4698 { 4699 /* When changing a call into a noreturn call, cfg cleanup 4700 is needed to fix up the noreturn call. */ 4701 if (!was_noreturn 4702 && is_gimple_call (stmt) && gimple_call_noreturn_p (stmt)) 4703 el_to_fixup.safe_push (stmt); 4704 /* When changing a condition or switch into one we know what 4705 edge will be executed, schedule a cfg cleanup. */ 4706 if ((gimple_code (stmt) == GIMPLE_COND 4707 && (gimple_cond_true_p (as_a <gcond *> (stmt)) 4708 || gimple_cond_false_p (as_a <gcond *> (stmt)))) 4709 || (gimple_code (stmt) == GIMPLE_SWITCH 4710 && TREE_CODE (gimple_switch_index 4711 (as_a <gswitch *> (stmt))) == INTEGER_CST)) 4712 el_todo |= TODO_cleanup_cfg; 4713 /* If we removed EH side-effects from the statement, clean 4714 its EH information. */ 4715 if (maybe_clean_or_replace_eh_stmt (old_stmt, stmt)) 4716 { 4717 bitmap_set_bit (need_eh_cleanup, 4718 gimple_bb (stmt)->index); 4719 if (dump_file && (dump_flags & TDF_DETAILS)) 4720 fprintf (dump_file, " Removed EH side-effects.\n"); 4721 } 4722 /* Likewise for AB side-effects. */ 4723 if (can_make_abnormal_goto 4724 && !stmt_can_make_abnormal_goto (stmt)) 4725 { 4726 bitmap_set_bit (need_ab_cleanup, 4727 gimple_bb (stmt)->index); 4728 if (dump_file && (dump_flags & TDF_DETAILS)) 4729 fprintf (dump_file, " Removed AB side-effects.\n"); 4730 } 4731 update_stmt (stmt); 4732 if (vdef != gimple_vdef (stmt)) 4733 VN_INFO (vdef)->valnum = vuse; 4734 } 4735 4736 /* Make new values available - for fully redundant LHS we 4737 continue with the next stmt above and skip this. */ 4738 def_operand_p defp; 4739 FOR_EACH_SSA_DEF_OPERAND (defp, stmt, iter, SSA_OP_DEF) 4740 eliminate_push_avail (DEF_FROM_PTR (defp)); 4741 } 4742 4743 /* Replace destination PHI arguments. */ 4744 edge_iterator ei; 4745 edge e; 4746 FOR_EACH_EDGE (e, ei, b->succs) 4747 { 4748 for (gphi_iterator gsi = gsi_start_phis (e->dest); 4749 !gsi_end_p (gsi); 4750 gsi_next (&gsi)) 4751 { 4752 gphi *phi = gsi.phi (); 4753 use_operand_p use_p = PHI_ARG_DEF_PTR_FROM_EDGE (phi, e); 4754 tree arg = USE_FROM_PTR (use_p); 4755 if (TREE_CODE (arg) != SSA_NAME 4756 || virtual_operand_p (arg)) 4757 continue; 4758 tree sprime = eliminate_avail (arg); 4759 if (sprime && may_propagate_copy (arg, sprime)) 4760 { 4761 propagate_value (use_p, sprime); 4762 if (TREE_CODE (sprime) == SSA_NAME) 4763 gimple_set_plf (SSA_NAME_DEF_STMT (sprime), NECESSARY, true); 4764 } 4765 } 4766 } 4767 return NULL; 4768 } 4769 4770 /* Make no longer available leaders no longer available. */ 4771 4772 void 4773 eliminate_dom_walker::after_dom_children (basic_block) 4774 { 4775 tree entry; 4776 while ((entry = el_avail_stack.pop ()) != NULL_TREE) 4777 { 4778 tree valnum = VN_INFO (entry)->valnum; 4779 tree old = el_avail[SSA_NAME_VERSION (valnum)]; 4780 if (old == entry) 4781 el_avail[SSA_NAME_VERSION (valnum)] = NULL_TREE; 4782 else 4783 el_avail[SSA_NAME_VERSION (valnum)] = entry; 4784 } 4785 } 4786 4787 /* Eliminate fully redundant computations. */ 4788 4789 static unsigned int 4790 eliminate (bool do_pre) 4791 { 4792 gimple_stmt_iterator gsi; 4793 gimple *stmt; 4794 4795 need_eh_cleanup = BITMAP_ALLOC (NULL); 4796 need_ab_cleanup = BITMAP_ALLOC (NULL); 4797 4798 el_to_remove.create (0); 4799 el_to_fixup.create (0); 4800 el_todo = 0; 4801 el_avail.create (num_ssa_names); 4802 el_avail_stack.create (0); 4803 4804 eliminate_dom_walker (CDI_DOMINATORS, 4805 do_pre).walk (cfun->cfg->x_entry_block_ptr); 4806 4807 el_avail.release (); 4808 el_avail_stack.release (); 4809 4810 /* We cannot remove stmts during BB walk, especially not release SSA 4811 names there as this confuses the VN machinery. The stmts ending 4812 up in el_to_remove are either stores or simple copies. 4813 Remove stmts in reverse order to make debug stmt creation possible. */ 4814 while (!el_to_remove.is_empty ()) 4815 { 4816 stmt = el_to_remove.pop (); 4817 4818 if (dump_file && (dump_flags & TDF_DETAILS)) 4819 { 4820 fprintf (dump_file, "Removing dead stmt "); 4821 print_gimple_stmt (dump_file, stmt, 0, 0); 4822 } 4823 4824 tree lhs; 4825 if (gimple_code (stmt) == GIMPLE_PHI) 4826 lhs = gimple_phi_result (stmt); 4827 else 4828 lhs = gimple_get_lhs (stmt); 4829 4830 if (lhs 4831 && inserted_exprs 4832 && TREE_CODE (lhs) == SSA_NAME) 4833 bitmap_clear_bit (inserted_exprs, SSA_NAME_VERSION (lhs)); 4834 4835 gsi = gsi_for_stmt (stmt); 4836 if (gimple_code (stmt) == GIMPLE_PHI) 4837 remove_phi_node (&gsi, true); 4838 else 4839 { 4840 basic_block bb = gimple_bb (stmt); 4841 unlink_stmt_vdef (stmt); 4842 if (gsi_remove (&gsi, true)) 4843 bitmap_set_bit (need_eh_cleanup, bb->index); 4844 if (is_gimple_call (stmt) && stmt_can_make_abnormal_goto (stmt)) 4845 bitmap_set_bit (need_ab_cleanup, bb->index); 4846 release_defs (stmt); 4847 } 4848 4849 /* Removing a stmt may expose a forwarder block. */ 4850 el_todo |= TODO_cleanup_cfg; 4851 } 4852 el_to_remove.release (); 4853 4854 /* Fixup stmts that became noreturn calls. This may require splitting 4855 blocks and thus isn't possible during the dominator walk. Do this 4856 in reverse order so we don't inadvertedly remove a stmt we want to 4857 fixup by visiting a dominating now noreturn call first. */ 4858 while (!el_to_fixup.is_empty ()) 4859 { 4860 stmt = el_to_fixup.pop (); 4861 4862 if (dump_file && (dump_flags & TDF_DETAILS)) 4863 { 4864 fprintf (dump_file, "Fixing up noreturn call "); 4865 print_gimple_stmt (dump_file, stmt, 0, 0); 4866 } 4867 4868 if (fixup_noreturn_call (stmt)) 4869 el_todo |= TODO_cleanup_cfg; 4870 } 4871 el_to_fixup.release (); 4872 4873 return el_todo; 4874 } 4875 4876 /* Perform CFG cleanups made necessary by elimination. */ 4877 4878 static unsigned 4879 fini_eliminate (void) 4880 { 4881 bool do_eh_cleanup = !bitmap_empty_p (need_eh_cleanup); 4882 bool do_ab_cleanup = !bitmap_empty_p (need_ab_cleanup); 4883 4884 if (do_eh_cleanup) 4885 gimple_purge_all_dead_eh_edges (need_eh_cleanup); 4886 4887 if (do_ab_cleanup) 4888 gimple_purge_all_dead_abnormal_call_edges (need_ab_cleanup); 4889 4890 BITMAP_FREE (need_eh_cleanup); 4891 BITMAP_FREE (need_ab_cleanup); 4892 4893 if (do_eh_cleanup || do_ab_cleanup) 4894 return TODO_cleanup_cfg; 4895 return 0; 4896 } 4897 4898 /* Borrow a bit of tree-ssa-dce.c for the moment. 4899 XXX: In 4.1, we should be able to just run a DCE pass after PRE, though 4900 this may be a bit faster, and we may want critical edges kept split. */ 4901 4902 /* If OP's defining statement has not already been determined to be necessary, 4903 mark that statement necessary. Return the stmt, if it is newly 4904 necessary. */ 4905 4906 static inline gimple * 4907 mark_operand_necessary (tree op) 4908 { 4909 gimple *stmt; 4910 4911 gcc_assert (op); 4912 4913 if (TREE_CODE (op) != SSA_NAME) 4914 return NULL; 4915 4916 stmt = SSA_NAME_DEF_STMT (op); 4917 gcc_assert (stmt); 4918 4919 if (gimple_plf (stmt, NECESSARY) 4920 || gimple_nop_p (stmt)) 4921 return NULL; 4922 4923 gimple_set_plf (stmt, NECESSARY, true); 4924 return stmt; 4925 } 4926 4927 /* Because we don't follow exactly the standard PRE algorithm, and decide not 4928 to insert PHI nodes sometimes, and because value numbering of casts isn't 4929 perfect, we sometimes end up inserting dead code. This simple DCE-like 4930 pass removes any insertions we made that weren't actually used. */ 4931 4932 static void 4933 remove_dead_inserted_code (void) 4934 { 4935 bitmap worklist; 4936 unsigned i; 4937 bitmap_iterator bi; 4938 gimple *t; 4939 4940 worklist = BITMAP_ALLOC (NULL); 4941 EXECUTE_IF_SET_IN_BITMAP (inserted_exprs, 0, i, bi) 4942 { 4943 t = SSA_NAME_DEF_STMT (ssa_name (i)); 4944 if (gimple_plf (t, NECESSARY)) 4945 bitmap_set_bit (worklist, i); 4946 } 4947 while (!bitmap_empty_p (worklist)) 4948 { 4949 i = bitmap_first_set_bit (worklist); 4950 bitmap_clear_bit (worklist, i); 4951 t = SSA_NAME_DEF_STMT (ssa_name (i)); 4952 4953 /* PHI nodes are somewhat special in that each PHI alternative has 4954 data and control dependencies. All the statements feeding the 4955 PHI node's arguments are always necessary. */ 4956 if (gimple_code (t) == GIMPLE_PHI) 4957 { 4958 unsigned k; 4959 4960 for (k = 0; k < gimple_phi_num_args (t); k++) 4961 { 4962 tree arg = PHI_ARG_DEF (t, k); 4963 if (TREE_CODE (arg) == SSA_NAME) 4964 { 4965 gimple *n = mark_operand_necessary (arg); 4966 if (n) 4967 bitmap_set_bit (worklist, SSA_NAME_VERSION (arg)); 4968 } 4969 } 4970 } 4971 else 4972 { 4973 /* Propagate through the operands. Examine all the USE, VUSE and 4974 VDEF operands in this statement. Mark all the statements 4975 which feed this statement's uses as necessary. */ 4976 ssa_op_iter iter; 4977 tree use; 4978 4979 /* The operands of VDEF expressions are also needed as they 4980 represent potential definitions that may reach this 4981 statement (VDEF operands allow us to follow def-def 4982 links). */ 4983 4984 FOR_EACH_SSA_TREE_OPERAND (use, t, iter, SSA_OP_ALL_USES) 4985 { 4986 gimple *n = mark_operand_necessary (use); 4987 if (n) 4988 bitmap_set_bit (worklist, SSA_NAME_VERSION (use)); 4989 } 4990 } 4991 } 4992 4993 EXECUTE_IF_SET_IN_BITMAP (inserted_exprs, 0, i, bi) 4994 { 4995 t = SSA_NAME_DEF_STMT (ssa_name (i)); 4996 if (!gimple_plf (t, NECESSARY)) 4997 { 4998 gimple_stmt_iterator gsi; 4999 5000 if (dump_file && (dump_flags & TDF_DETAILS)) 5001 { 5002 fprintf (dump_file, "Removing unnecessary insertion:"); 5003 print_gimple_stmt (dump_file, t, 0, 0); 5004 } 5005 5006 gsi = gsi_for_stmt (t); 5007 if (gimple_code (t) == GIMPLE_PHI) 5008 remove_phi_node (&gsi, true); 5009 else 5010 { 5011 gsi_remove (&gsi, true); 5012 release_defs (t); 5013 } 5014 } 5015 } 5016 BITMAP_FREE (worklist); 5017 } 5018 5019 5020 /* Initialize data structures used by PRE. */ 5021 5022 static void 5023 init_pre (void) 5024 { 5025 basic_block bb; 5026 5027 next_expression_id = 1; 5028 expressions.create (0); 5029 expressions.safe_push (NULL); 5030 value_expressions.create (get_max_value_id () + 1); 5031 value_expressions.safe_grow_cleared (get_max_value_id () + 1); 5032 name_to_id.create (0); 5033 5034 inserted_exprs = BITMAP_ALLOC (NULL); 5035 5036 connect_infinite_loops_to_exit (); 5037 memset (&pre_stats, 0, sizeof (pre_stats)); 5038 5039 alloc_aux_for_blocks (sizeof (struct bb_bitmap_sets)); 5040 5041 calculate_dominance_info (CDI_DOMINATORS); 5042 5043 bitmap_obstack_initialize (&grand_bitmap_obstack); 5044 phi_translate_table = new hash_table<expr_pred_trans_d> (5110); 5045 expression_to_id = new hash_table<pre_expr_d> (num_ssa_names * 3); 5046 FOR_ALL_BB_FN (bb, cfun) 5047 { 5048 EXP_GEN (bb) = bitmap_set_new (); 5049 PHI_GEN (bb) = bitmap_set_new (); 5050 TMP_GEN (bb) = bitmap_set_new (); 5051 AVAIL_OUT (bb) = bitmap_set_new (); 5052 } 5053 } 5054 5055 5056 /* Deallocate data structures used by PRE. */ 5057 5058 static void 5059 fini_pre () 5060 { 5061 value_expressions.release (); 5062 BITMAP_FREE (inserted_exprs); 5063 bitmap_obstack_release (&grand_bitmap_obstack); 5064 bitmap_set_pool.release (); 5065 pre_expr_pool.release (); 5066 delete phi_translate_table; 5067 phi_translate_table = NULL; 5068 delete expression_to_id; 5069 expression_to_id = NULL; 5070 name_to_id.release (); 5071 5072 free_aux_for_blocks (); 5073 } 5074 5075 namespace { 5076 5077 const pass_data pass_data_pre = 5078 { 5079 GIMPLE_PASS, /* type */ 5080 "pre", /* name */ 5081 OPTGROUP_NONE, /* optinfo_flags */ 5082 TV_TREE_PRE, /* tv_id */ 5083 /* PROP_no_crit_edges is ensured by placing pass_split_crit_edges before 5084 pass_pre. */ 5085 ( PROP_no_crit_edges | PROP_cfg | PROP_ssa ), /* properties_required */ 5086 0, /* properties_provided */ 5087 PROP_no_crit_edges, /* properties_destroyed */ 5088 TODO_rebuild_alias, /* todo_flags_start */ 5089 0, /* todo_flags_finish */ 5090 }; 5091 5092 class pass_pre : public gimple_opt_pass 5093 { 5094 public: 5095 pass_pre (gcc::context *ctxt) 5096 : gimple_opt_pass (pass_data_pre, ctxt) 5097 {} 5098 5099 /* opt_pass methods: */ 5100 virtual bool gate (function *) 5101 { return flag_tree_pre != 0 || flag_code_hoisting != 0; } 5102 virtual unsigned int execute (function *); 5103 5104 }; // class pass_pre 5105 5106 unsigned int 5107 pass_pre::execute (function *fun) 5108 { 5109 unsigned int todo = 0; 5110 5111 do_partial_partial = 5112 flag_tree_partial_pre && optimize_function_for_speed_p (fun); 5113 5114 /* This has to happen before SCCVN runs because 5115 loop_optimizer_init may create new phis, etc. */ 5116 loop_optimizer_init (LOOPS_NORMAL); 5117 5118 if (!run_scc_vn (VN_WALK)) 5119 { 5120 loop_optimizer_finalize (); 5121 return 0; 5122 } 5123 5124 init_pre (); 5125 scev_initialize (); 5126 5127 /* Collect and value number expressions computed in each basic block. */ 5128 compute_avail (); 5129 5130 /* Insert can get quite slow on an incredibly large number of basic 5131 blocks due to some quadratic behavior. Until this behavior is 5132 fixed, don't run it when he have an incredibly large number of 5133 bb's. If we aren't going to run insert, there is no point in 5134 computing ANTIC, either, even though it's plenty fast. */ 5135 if (n_basic_blocks_for_fn (fun) < 4000) 5136 { 5137 compute_antic (); 5138 insert (); 5139 } 5140 5141 /* Make sure to remove fake edges before committing our inserts. 5142 This makes sure we don't end up with extra critical edges that 5143 we would need to split. */ 5144 remove_fake_exit_edges (); 5145 gsi_commit_edge_inserts (); 5146 5147 /* Eliminate folds statements which might (should not...) end up 5148 not keeping virtual operands up-to-date. */ 5149 gcc_assert (!need_ssa_update_p (fun)); 5150 5151 /* Remove all the redundant expressions. */ 5152 todo |= eliminate (true); 5153 5154 statistics_counter_event (fun, "Insertions", pre_stats.insertions); 5155 statistics_counter_event (fun, "PA inserted", pre_stats.pa_insert); 5156 statistics_counter_event (fun, "HOIST inserted", pre_stats.hoist_insert); 5157 statistics_counter_event (fun, "New PHIs", pre_stats.phis); 5158 statistics_counter_event (fun, "Eliminated", pre_stats.eliminations); 5159 5160 clear_expression_ids (); 5161 remove_dead_inserted_code (); 5162 5163 scev_finalize (); 5164 fini_pre (); 5165 todo |= fini_eliminate (); 5166 loop_optimizer_finalize (); 5167 5168 /* Restore SSA info before tail-merging as that resets it as well. */ 5169 scc_vn_restore_ssa_info (); 5170 5171 /* TODO: tail_merge_optimize may merge all predecessors of a block, in which 5172 case we can merge the block with the remaining predecessor of the block. 5173 It should either: 5174 - call merge_blocks after each tail merge iteration 5175 - call merge_blocks after all tail merge iterations 5176 - mark TODO_cleanup_cfg when necessary 5177 - share the cfg cleanup with fini_pre. */ 5178 todo |= tail_merge_optimize (todo); 5179 5180 free_scc_vn (); 5181 5182 /* Tail merging invalidates the virtual SSA web, together with 5183 cfg-cleanup opportunities exposed by PRE this will wreck the 5184 SSA updating machinery. So make sure to run update-ssa 5185 manually, before eventually scheduling cfg-cleanup as part of 5186 the todo. */ 5187 update_ssa (TODO_update_ssa_only_virtuals); 5188 5189 return todo; 5190 } 5191 5192 } // anon namespace 5193 5194 gimple_opt_pass * 5195 make_pass_pre (gcc::context *ctxt) 5196 { 5197 return new pass_pre (ctxt); 5198 } 5199 5200 namespace { 5201 5202 const pass_data pass_data_fre = 5203 { 5204 GIMPLE_PASS, /* type */ 5205 "fre", /* name */ 5206 OPTGROUP_NONE, /* optinfo_flags */ 5207 TV_TREE_FRE, /* tv_id */ 5208 ( PROP_cfg | PROP_ssa ), /* properties_required */ 5209 0, /* properties_provided */ 5210 0, /* properties_destroyed */ 5211 0, /* todo_flags_start */ 5212 0, /* todo_flags_finish */ 5213 }; 5214 5215 class pass_fre : public gimple_opt_pass 5216 { 5217 public: 5218 pass_fre (gcc::context *ctxt) 5219 : gimple_opt_pass (pass_data_fre, ctxt) 5220 {} 5221 5222 /* opt_pass methods: */ 5223 opt_pass * clone () { return new pass_fre (m_ctxt); } 5224 virtual bool gate (function *) { return flag_tree_fre != 0; } 5225 virtual unsigned int execute (function *); 5226 5227 }; // class pass_fre 5228 5229 unsigned int 5230 pass_fre::execute (function *fun) 5231 { 5232 unsigned int todo = 0; 5233 5234 if (!run_scc_vn (VN_WALKREWRITE)) 5235 return 0; 5236 5237 memset (&pre_stats, 0, sizeof (pre_stats)); 5238 5239 /* Remove all the redundant expressions. */ 5240 todo |= eliminate (false); 5241 5242 todo |= fini_eliminate (); 5243 5244 scc_vn_restore_ssa_info (); 5245 free_scc_vn (); 5246 5247 statistics_counter_event (fun, "Insertions", pre_stats.insertions); 5248 statistics_counter_event (fun, "Eliminated", pre_stats.eliminations); 5249 5250 return todo; 5251 } 5252 5253 } // anon namespace 5254 5255 gimple_opt_pass * 5256 make_pass_fre (gcc::context *ctxt) 5257 { 5258 return new pass_fre (ctxt); 5259 } 5260