1/* Control flow functions for trees. 2 Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006 3 Free Software Foundation, Inc. 4 Contributed by Diego Novillo <dnovillo@redhat.com> 5 6This file is part of GCC. 7 8GCC is free software; you can redistribute it and/or modify 9it under the terms of the GNU General Public License as published by 10the Free Software Foundation; either version 2, or (at your option) 11any later version. 12 13GCC is distributed in the hope that it will be useful, 14but WITHOUT ANY WARRANTY; without even the implied warranty of 15MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 16GNU General Public License for more details. 17 18You should have received a copy of the GNU General Public License 19along with GCC; see the file COPYING. If not, write to 20the Free Software Foundation, 51 Franklin Street, Fifth Floor, 21Boston, MA 02110-1301, USA. */ 22 23#include "config.h" 24#include "system.h" 25#include "coretypes.h" 26#include "tm.h" 27#include "tree.h" 28#include "rtl.h" 29#include "tm_p.h" 30#include "hard-reg-set.h" 31#include "basic-block.h" 32#include "output.h" 33#include "flags.h" 34#include "function.h" 35#include "expr.h" 36#include "ggc.h" 37#include "langhooks.h" 38#include "diagnostic.h" 39#include "tree-flow.h" 40#include "timevar.h" 41#include "tree-dump.h" 42#include "tree-pass.h" 43#include "toplev.h" 44#include "except.h" 45#include "cfgloop.h" 46#include "cfglayout.h" 47#include "hashtab.h" 48#include "tree-ssa-propagate.h" 49 50/* This file contains functions for building the Control Flow Graph (CFG) 51 for a function tree. */ 52 53/* Local declarations. */ 54 55/* Initial capacity for the basic block array. */ 56static const int initial_cfg_capacity = 20; 57 58/* This hash table allows us to efficiently lookup all CASE_LABEL_EXPRs 59 which use a particular edge. The CASE_LABEL_EXPRs are chained together 60 via their TREE_CHAIN field, which we clear after we're done with the 61 hash table to prevent problems with duplication of SWITCH_EXPRs. 62 63 Access to this list of CASE_LABEL_EXPRs allows us to efficiently 64 update the case vector in response to edge redirections. 65 66 Right now this table is set up and torn down at key points in the 67 compilation process. It would be nice if we could make the table 68 more persistent. The key is getting notification of changes to 69 the CFG (particularly edge removal, creation and redirection). */ 70 71struct edge_to_cases_elt 72{ 73 /* The edge itself. Necessary for hashing and equality tests. */ 74 edge e; 75 76 /* The case labels associated with this edge. We link these up via 77 their TREE_CHAIN field, then we wipe out the TREE_CHAIN fields 78 when we destroy the hash table. This prevents problems when copying 79 SWITCH_EXPRs. */ 80 tree case_labels; 81}; 82 83static htab_t edge_to_cases; 84 85/* CFG statistics. */ 86struct cfg_stats_d 87{ 88 long num_merged_labels; 89}; 90 91static struct cfg_stats_d cfg_stats; 92 93/* Nonzero if we found a computed goto while building basic blocks. */ 94static bool found_computed_goto; 95 96/* Basic blocks and flowgraphs. */ 97static basic_block create_bb (void *, void *, basic_block); 98static void make_blocks (tree); 99static void factor_computed_gotos (void); 100 101/* Edges. */ 102static void make_edges (void); 103static void make_cond_expr_edges (basic_block); 104static void make_switch_expr_edges (basic_block); 105static void make_goto_expr_edges (basic_block); 106static edge tree_redirect_edge_and_branch (edge, basic_block); 107static edge tree_try_redirect_by_replacing_jump (edge, basic_block); 108static unsigned int split_critical_edges (void); 109 110/* Various helpers. */ 111static inline bool stmt_starts_bb_p (tree, tree); 112static int tree_verify_flow_info (void); 113static void tree_make_forwarder_block (edge); 114static void tree_cfg2vcg (FILE *); 115static inline void change_bb_for_stmt (tree t, basic_block bb); 116 117/* Flowgraph optimization and cleanup. */ 118static void tree_merge_blocks (basic_block, basic_block); 119static bool tree_can_merge_blocks_p (basic_block, basic_block); 120static void remove_bb (basic_block); 121static edge find_taken_edge_computed_goto (basic_block, tree); 122static edge find_taken_edge_cond_expr (basic_block, tree); 123static edge find_taken_edge_switch_expr (basic_block, tree); 124static tree find_case_label_for_value (tree, tree); 125 126void 127init_empty_tree_cfg (void) 128{ 129 /* Initialize the basic block array. */ 130 init_flow (); 131 profile_status = PROFILE_ABSENT; 132 n_basic_blocks = NUM_FIXED_BLOCKS; 133 last_basic_block = NUM_FIXED_BLOCKS; 134 basic_block_info = VEC_alloc (basic_block, gc, initial_cfg_capacity); 135 VEC_safe_grow (basic_block, gc, basic_block_info, initial_cfg_capacity); 136 memset (VEC_address (basic_block, basic_block_info), 0, 137 sizeof (basic_block) * initial_cfg_capacity); 138 139 /* Build a mapping of labels to their associated blocks. */ 140 label_to_block_map = VEC_alloc (basic_block, gc, initial_cfg_capacity); 141 VEC_safe_grow (basic_block, gc, label_to_block_map, initial_cfg_capacity); 142 memset (VEC_address (basic_block, label_to_block_map), 143 0, sizeof (basic_block) * initial_cfg_capacity); 144 145 SET_BASIC_BLOCK (ENTRY_BLOCK, ENTRY_BLOCK_PTR); 146 SET_BASIC_BLOCK (EXIT_BLOCK, EXIT_BLOCK_PTR); 147 ENTRY_BLOCK_PTR->next_bb = EXIT_BLOCK_PTR; 148 EXIT_BLOCK_PTR->prev_bb = ENTRY_BLOCK_PTR; 149} 150 151/*--------------------------------------------------------------------------- 152 Create basic blocks 153---------------------------------------------------------------------------*/ 154 155/* Entry point to the CFG builder for trees. TP points to the list of 156 statements to be added to the flowgraph. */ 157 158static void 159build_tree_cfg (tree *tp) 160{ 161 /* Register specific tree functions. */ 162 tree_register_cfg_hooks (); 163 164 memset ((void *) &cfg_stats, 0, sizeof (cfg_stats)); 165 166 init_empty_tree_cfg (); 167 168 found_computed_goto = 0; 169 make_blocks (*tp); 170 171 /* Computed gotos are hell to deal with, especially if there are 172 lots of them with a large number of destinations. So we factor 173 them to a common computed goto location before we build the 174 edge list. After we convert back to normal form, we will un-factor 175 the computed gotos since factoring introduces an unwanted jump. */ 176 if (found_computed_goto) 177 factor_computed_gotos (); 178 179 /* Make sure there is always at least one block, even if it's empty. */ 180 if (n_basic_blocks == NUM_FIXED_BLOCKS) 181 create_empty_bb (ENTRY_BLOCK_PTR); 182 183 /* Adjust the size of the array. */ 184 if (VEC_length (basic_block, basic_block_info) < (size_t) n_basic_blocks) 185 { 186 size_t old_size = VEC_length (basic_block, basic_block_info); 187 basic_block *p; 188 VEC_safe_grow (basic_block, gc, basic_block_info, n_basic_blocks); 189 p = VEC_address (basic_block, basic_block_info); 190 memset (&p[old_size], 0, 191 sizeof (basic_block) * (n_basic_blocks - old_size)); 192 } 193 194 /* To speed up statement iterator walks, we first purge dead labels. */ 195 cleanup_dead_labels (); 196 197 /* Group case nodes to reduce the number of edges. 198 We do this after cleaning up dead labels because otherwise we miss 199 a lot of obvious case merging opportunities. */ 200 group_case_labels (); 201 202 /* Create the edges of the flowgraph. */ 203 make_edges (); 204 205 /* Debugging dumps. */ 206 207 /* Write the flowgraph to a VCG file. */ 208 { 209 int local_dump_flags; 210 FILE *vcg_file = dump_begin (TDI_vcg, &local_dump_flags); 211 if (vcg_file) 212 { 213 tree_cfg2vcg (vcg_file); 214 dump_end (TDI_vcg, vcg_file); 215 } 216 } 217 218#ifdef ENABLE_CHECKING 219 verify_stmts (); 220#endif 221 222 /* Dump a textual representation of the flowgraph. */ 223 if (dump_file) 224 dump_tree_cfg (dump_file, dump_flags); 225} 226 227static unsigned int 228execute_build_cfg (void) 229{ 230 build_tree_cfg (&DECL_SAVED_TREE (current_function_decl)); 231 return 0; 232} 233 234struct tree_opt_pass pass_build_cfg = 235{ 236 "cfg", /* name */ 237 NULL, /* gate */ 238 execute_build_cfg, /* execute */ 239 NULL, /* sub */ 240 NULL, /* next */ 241 0, /* static_pass_number */ 242 TV_TREE_CFG, /* tv_id */ 243 PROP_gimple_leh, /* properties_required */ 244 PROP_cfg, /* properties_provided */ 245 0, /* properties_destroyed */ 246 0, /* todo_flags_start */ 247 TODO_verify_stmts, /* todo_flags_finish */ 248 0 /* letter */ 249}; 250 251/* Search the CFG for any computed gotos. If found, factor them to a 252 common computed goto site. Also record the location of that site so 253 that we can un-factor the gotos after we have converted back to 254 normal form. */ 255 256static void 257factor_computed_gotos (void) 258{ 259 basic_block bb; 260 tree factored_label_decl = NULL; 261 tree var = NULL; 262 tree factored_computed_goto_label = NULL; 263 tree factored_computed_goto = NULL; 264 265 /* We know there are one or more computed gotos in this function. 266 Examine the last statement in each basic block to see if the block 267 ends with a computed goto. */ 268 269 FOR_EACH_BB (bb) 270 { 271 block_stmt_iterator bsi = bsi_last (bb); 272 tree last; 273 274 if (bsi_end_p (bsi)) 275 continue; 276 last = bsi_stmt (bsi); 277 278 /* Ignore the computed goto we create when we factor the original 279 computed gotos. */ 280 if (last == factored_computed_goto) 281 continue; 282 283 /* If the last statement is a computed goto, factor it. */ 284 if (computed_goto_p (last)) 285 { 286 tree assignment; 287 288 /* The first time we find a computed goto we need to create 289 the factored goto block and the variable each original 290 computed goto will use for their goto destination. */ 291 if (! factored_computed_goto) 292 { 293 basic_block new_bb = create_empty_bb (bb); 294 block_stmt_iterator new_bsi = bsi_start (new_bb); 295 296 /* Create the destination of the factored goto. Each original 297 computed goto will put its desired destination into this 298 variable and jump to the label we create immediately 299 below. */ 300 var = create_tmp_var (ptr_type_node, "gotovar"); 301 302 /* Build a label for the new block which will contain the 303 factored computed goto. */ 304 factored_label_decl = create_artificial_label (); 305 factored_computed_goto_label 306 = build1 (LABEL_EXPR, void_type_node, factored_label_decl); 307 bsi_insert_after (&new_bsi, factored_computed_goto_label, 308 BSI_NEW_STMT); 309 310 /* Build our new computed goto. */ 311 factored_computed_goto = build1 (GOTO_EXPR, void_type_node, var); 312 bsi_insert_after (&new_bsi, factored_computed_goto, 313 BSI_NEW_STMT); 314 } 315 316 /* Copy the original computed goto's destination into VAR. */ 317 assignment = build2 (MODIFY_EXPR, ptr_type_node, 318 var, GOTO_DESTINATION (last)); 319 bsi_insert_before (&bsi, assignment, BSI_SAME_STMT); 320 321 /* And re-vector the computed goto to the new destination. */ 322 GOTO_DESTINATION (last) = factored_label_decl; 323 } 324 } 325} 326 327 328/* Build a flowgraph for the statement_list STMT_LIST. */ 329 330static void 331make_blocks (tree stmt_list) 332{ 333 tree_stmt_iterator i = tsi_start (stmt_list); 334 tree stmt = NULL; 335 bool start_new_block = true; 336 bool first_stmt_of_list = true; 337 basic_block bb = ENTRY_BLOCK_PTR; 338 339 while (!tsi_end_p (i)) 340 { 341 tree prev_stmt; 342 343 prev_stmt = stmt; 344 stmt = tsi_stmt (i); 345 346 /* If the statement starts a new basic block or if we have determined 347 in a previous pass that we need to create a new block for STMT, do 348 so now. */ 349 if (start_new_block || stmt_starts_bb_p (stmt, prev_stmt)) 350 { 351 if (!first_stmt_of_list) 352 stmt_list = tsi_split_statement_list_before (&i); 353 bb = create_basic_block (stmt_list, NULL, bb); 354 start_new_block = false; 355 } 356 357 /* Now add STMT to BB and create the subgraphs for special statement 358 codes. */ 359 set_bb_for_stmt (stmt, bb); 360 361 if (computed_goto_p (stmt)) 362 found_computed_goto = true; 363 364 /* If STMT is a basic block terminator, set START_NEW_BLOCK for the 365 next iteration. */ 366 if (stmt_ends_bb_p (stmt)) 367 start_new_block = true; 368 369 tsi_next (&i); 370 first_stmt_of_list = false; 371 } 372} 373 374 375/* Create and return a new empty basic block after bb AFTER. */ 376 377static basic_block 378create_bb (void *h, void *e, basic_block after) 379{ 380 basic_block bb; 381 382 gcc_assert (!e); 383 384 /* Create and initialize a new basic block. Since alloc_block uses 385 ggc_alloc_cleared to allocate a basic block, we do not have to 386 clear the newly allocated basic block here. */ 387 bb = alloc_block (); 388 389 bb->index = last_basic_block; 390 bb->flags = BB_NEW; 391 bb->stmt_list = h ? (tree) h : alloc_stmt_list (); 392 393 /* Add the new block to the linked list of blocks. */ 394 link_block (bb, after); 395 396 /* Grow the basic block array if needed. */ 397 if ((size_t) last_basic_block == VEC_length (basic_block, basic_block_info)) 398 { 399 size_t old_size = VEC_length (basic_block, basic_block_info); 400 size_t new_size = last_basic_block + (last_basic_block + 3) / 4; 401 basic_block *p; 402 VEC_safe_grow (basic_block, gc, basic_block_info, new_size); 403 p = VEC_address (basic_block, basic_block_info); 404 memset (&p[old_size], 0, sizeof (basic_block) * (new_size - old_size)); 405 } 406 407 /* Add the newly created block to the array. */ 408 SET_BASIC_BLOCK (last_basic_block, bb); 409 410 n_basic_blocks++; 411 last_basic_block++; 412 413 return bb; 414} 415 416 417/*--------------------------------------------------------------------------- 418 Edge creation 419---------------------------------------------------------------------------*/ 420 421/* Fold COND_EXPR_COND of each COND_EXPR. */ 422 423void 424fold_cond_expr_cond (void) 425{ 426 basic_block bb; 427 428 FOR_EACH_BB (bb) 429 { 430 tree stmt = last_stmt (bb); 431 432 if (stmt 433 && TREE_CODE (stmt) == COND_EXPR) 434 { 435 tree cond; 436 bool zerop, onep; 437 438 fold_defer_overflow_warnings (); 439 cond = fold (COND_EXPR_COND (stmt)); 440 zerop = integer_zerop (cond); 441 onep = integer_onep (cond); 442 fold_undefer_overflow_warnings (((zerop || onep) 443 && !TREE_NO_WARNING (stmt)), 444 stmt, 445 WARN_STRICT_OVERFLOW_CONDITIONAL); 446 if (zerop) 447 COND_EXPR_COND (stmt) = boolean_false_node; 448 else if (onep) 449 COND_EXPR_COND (stmt) = boolean_true_node; 450 } 451 } 452} 453 454/* Join all the blocks in the flowgraph. */ 455 456static void 457make_edges (void) 458{ 459 basic_block bb; 460 struct omp_region *cur_region = NULL; 461 462 /* Create an edge from entry to the first block with executable 463 statements in it. */ 464 make_edge (ENTRY_BLOCK_PTR, BASIC_BLOCK (NUM_FIXED_BLOCKS), EDGE_FALLTHRU); 465 466 /* Traverse the basic block array placing edges. */ 467 FOR_EACH_BB (bb) 468 { 469 tree last = last_stmt (bb); 470 bool fallthru; 471 472 if (last) 473 { 474 enum tree_code code = TREE_CODE (last); 475 switch (code) 476 { 477 case GOTO_EXPR: 478 make_goto_expr_edges (bb); 479 fallthru = false; 480 break; 481 case RETURN_EXPR: 482 make_edge (bb, EXIT_BLOCK_PTR, 0); 483 fallthru = false; 484 break; 485 case COND_EXPR: 486 make_cond_expr_edges (bb); 487 fallthru = false; 488 break; 489 case SWITCH_EXPR: 490 make_switch_expr_edges (bb); 491 fallthru = false; 492 break; 493 case RESX_EXPR: 494 make_eh_edges (last); 495 fallthru = false; 496 break; 497 498 case CALL_EXPR: 499 /* If this function receives a nonlocal goto, then we need to 500 make edges from this call site to all the nonlocal goto 501 handlers. */ 502 if (tree_can_make_abnormal_goto (last)) 503 make_abnormal_goto_edges (bb, true); 504 505 /* If this statement has reachable exception handlers, then 506 create abnormal edges to them. */ 507 make_eh_edges (last); 508 509 /* Some calls are known not to return. */ 510 fallthru = !(call_expr_flags (last) & ECF_NORETURN); 511 break; 512 513 case MODIFY_EXPR: 514 if (is_ctrl_altering_stmt (last)) 515 { 516 /* A MODIFY_EXPR may have a CALL_EXPR on its RHS and the 517 CALL_EXPR may have an abnormal edge. Search the RHS for 518 this case and create any required edges. */ 519 if (tree_can_make_abnormal_goto (last)) 520 make_abnormal_goto_edges (bb, true); 521 522 make_eh_edges (last); 523 } 524 fallthru = true; 525 break; 526 527 case OMP_PARALLEL: 528 case OMP_FOR: 529 case OMP_SINGLE: 530 case OMP_MASTER: 531 case OMP_ORDERED: 532 case OMP_CRITICAL: 533 case OMP_SECTION: 534 cur_region = new_omp_region (bb, code, cur_region); 535 fallthru = true; 536 break; 537 538 case OMP_SECTIONS: 539 cur_region = new_omp_region (bb, code, cur_region); 540 fallthru = false; 541 break; 542 543 case OMP_RETURN: 544 /* In the case of an OMP_SECTION, the edge will go somewhere 545 other than the next block. This will be created later. */ 546 cur_region->exit = bb; 547 fallthru = cur_region->type != OMP_SECTION; 548 cur_region = cur_region->outer; 549 break; 550 551 case OMP_CONTINUE: 552 cur_region->cont = bb; 553 switch (cur_region->type) 554 { 555 case OMP_FOR: 556 /* ??? Technically there should be a some sort of loopback 557 edge here, but it goes to a block that doesn't exist yet, 558 and without it, updating the ssa form would be a real 559 bear. Fortunately, we don't yet do ssa before expanding 560 these nodes. */ 561 break; 562 563 case OMP_SECTIONS: 564 /* Wire up the edges into and out of the nested sections. */ 565 /* ??? Similarly wrt loopback. */ 566 { 567 struct omp_region *i; 568 for (i = cur_region->inner; i ; i = i->next) 569 { 570 gcc_assert (i->type == OMP_SECTION); 571 make_edge (cur_region->entry, i->entry, 0); 572 make_edge (i->exit, bb, EDGE_FALLTHRU); 573 } 574 } 575 break; 576 577 default: 578 gcc_unreachable (); 579 } 580 fallthru = true; 581 break; 582 583 default: 584 gcc_assert (!stmt_ends_bb_p (last)); 585 fallthru = true; 586 } 587 } 588 else 589 fallthru = true; 590 591 if (fallthru) 592 make_edge (bb, bb->next_bb, EDGE_FALLTHRU); 593 } 594 595 if (root_omp_region) 596 free_omp_regions (); 597 598 /* Fold COND_EXPR_COND of each COND_EXPR. */ 599 fold_cond_expr_cond (); 600 601 /* Clean up the graph and warn for unreachable code. */ 602 cleanup_tree_cfg (); 603} 604 605 606/* Create the edges for a COND_EXPR starting at block BB. 607 At this point, both clauses must contain only simple gotos. */ 608 609static void 610make_cond_expr_edges (basic_block bb) 611{ 612 tree entry = last_stmt (bb); 613 basic_block then_bb, else_bb; 614 tree then_label, else_label; 615 edge e; 616 617 gcc_assert (entry); 618 gcc_assert (TREE_CODE (entry) == COND_EXPR); 619 620 /* Entry basic blocks for each component. */ 621 then_label = GOTO_DESTINATION (COND_EXPR_THEN (entry)); 622 else_label = GOTO_DESTINATION (COND_EXPR_ELSE (entry)); 623 then_bb = label_to_block (then_label); 624 else_bb = label_to_block (else_label); 625 626 e = make_edge (bb, then_bb, EDGE_TRUE_VALUE); 627#ifdef USE_MAPPED_LOCATION 628 e->goto_locus = EXPR_LOCATION (COND_EXPR_THEN (entry)); 629#else 630 e->goto_locus = EXPR_LOCUS (COND_EXPR_THEN (entry)); 631#endif 632 e = make_edge (bb, else_bb, EDGE_FALSE_VALUE); 633 if (e) 634 { 635#ifdef USE_MAPPED_LOCATION 636 e->goto_locus = EXPR_LOCATION (COND_EXPR_ELSE (entry)); 637#else 638 e->goto_locus = EXPR_LOCUS (COND_EXPR_ELSE (entry)); 639#endif 640 } 641} 642 643/* Hashing routine for EDGE_TO_CASES. */ 644 645static hashval_t 646edge_to_cases_hash (const void *p) 647{ 648 edge e = ((struct edge_to_cases_elt *)p)->e; 649 650 /* Hash on the edge itself (which is a pointer). */ 651 return htab_hash_pointer (e); 652} 653 654/* Equality routine for EDGE_TO_CASES, edges are unique, so testing 655 for equality is just a pointer comparison. */ 656 657static int 658edge_to_cases_eq (const void *p1, const void *p2) 659{ 660 edge e1 = ((struct edge_to_cases_elt *)p1)->e; 661 edge e2 = ((struct edge_to_cases_elt *)p2)->e; 662 663 return e1 == e2; 664} 665 666/* Called for each element in the hash table (P) as we delete the 667 edge to cases hash table. 668 669 Clear all the TREE_CHAINs to prevent problems with copying of 670 SWITCH_EXPRs and structure sharing rules, then free the hash table 671 element. */ 672 673static void 674edge_to_cases_cleanup (void *p) 675{ 676 struct edge_to_cases_elt *elt = (struct edge_to_cases_elt *) p; 677 tree t, next; 678 679 for (t = elt->case_labels; t; t = next) 680 { 681 next = TREE_CHAIN (t); 682 TREE_CHAIN (t) = NULL; 683 } 684 free (p); 685} 686 687/* Start recording information mapping edges to case labels. */ 688 689void 690start_recording_case_labels (void) 691{ 692 gcc_assert (edge_to_cases == NULL); 693 694 edge_to_cases = htab_create (37, 695 edge_to_cases_hash, 696 edge_to_cases_eq, 697 edge_to_cases_cleanup); 698} 699 700/* Return nonzero if we are recording information for case labels. */ 701 702static bool 703recording_case_labels_p (void) 704{ 705 return (edge_to_cases != NULL); 706} 707 708/* Stop recording information mapping edges to case labels and 709 remove any information we have recorded. */ 710void 711end_recording_case_labels (void) 712{ 713 htab_delete (edge_to_cases); 714 edge_to_cases = NULL; 715} 716 717/* Record that CASE_LABEL (a CASE_LABEL_EXPR) references edge E. */ 718 719static void 720record_switch_edge (edge e, tree case_label) 721{ 722 struct edge_to_cases_elt *elt; 723 void **slot; 724 725 /* Build a hash table element so we can see if E is already 726 in the table. */ 727 elt = XNEW (struct edge_to_cases_elt); 728 elt->e = e; 729 elt->case_labels = case_label; 730 731 slot = htab_find_slot (edge_to_cases, elt, INSERT); 732 733 if (*slot == NULL) 734 { 735 /* E was not in the hash table. Install E into the hash table. */ 736 *slot = (void *)elt; 737 } 738 else 739 { 740 /* E was already in the hash table. Free ELT as we do not need it 741 anymore. */ 742 free (elt); 743 744 /* Get the entry stored in the hash table. */ 745 elt = (struct edge_to_cases_elt *) *slot; 746 747 /* Add it to the chain of CASE_LABEL_EXPRs referencing E. */ 748 TREE_CHAIN (case_label) = elt->case_labels; 749 elt->case_labels = case_label; 750 } 751} 752 753/* If we are inside a {start,end}_recording_cases block, then return 754 a chain of CASE_LABEL_EXPRs from T which reference E. 755 756 Otherwise return NULL. */ 757 758static tree 759get_cases_for_edge (edge e, tree t) 760{ 761 struct edge_to_cases_elt elt, *elt_p; 762 void **slot; 763 size_t i, n; 764 tree vec; 765 766 /* If we are not recording cases, then we do not have CASE_LABEL_EXPR 767 chains available. Return NULL so the caller can detect this case. */ 768 if (!recording_case_labels_p ()) 769 return NULL; 770 771restart: 772 elt.e = e; 773 elt.case_labels = NULL; 774 slot = htab_find_slot (edge_to_cases, &elt, NO_INSERT); 775 776 if (slot) 777 { 778 elt_p = (struct edge_to_cases_elt *)*slot; 779 return elt_p->case_labels; 780 } 781 782 /* If we did not find E in the hash table, then this must be the first 783 time we have been queried for information about E & T. Add all the 784 elements from T to the hash table then perform the query again. */ 785 786 vec = SWITCH_LABELS (t); 787 n = TREE_VEC_LENGTH (vec); 788 for (i = 0; i < n; i++) 789 { 790 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i)); 791 basic_block label_bb = label_to_block (lab); 792 record_switch_edge (find_edge (e->src, label_bb), TREE_VEC_ELT (vec, i)); 793 } 794 goto restart; 795} 796 797/* Create the edges for a SWITCH_EXPR starting at block BB. 798 At this point, the switch body has been lowered and the 799 SWITCH_LABELS filled in, so this is in effect a multi-way branch. */ 800 801static void 802make_switch_expr_edges (basic_block bb) 803{ 804 tree entry = last_stmt (bb); 805 size_t i, n; 806 tree vec; 807 808 vec = SWITCH_LABELS (entry); 809 n = TREE_VEC_LENGTH (vec); 810 811 for (i = 0; i < n; ++i) 812 { 813 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i)); 814 basic_block label_bb = label_to_block (lab); 815 make_edge (bb, label_bb, 0); 816 } 817} 818 819 820/* Return the basic block holding label DEST. */ 821 822basic_block 823label_to_block_fn (struct function *ifun, tree dest) 824{ 825 int uid = LABEL_DECL_UID (dest); 826 827 /* We would die hard when faced by an undefined label. Emit a label to 828 the very first basic block. This will hopefully make even the dataflow 829 and undefined variable warnings quite right. */ 830 if ((errorcount || sorrycount) && uid < 0) 831 { 832 block_stmt_iterator bsi = 833 bsi_start (BASIC_BLOCK (NUM_FIXED_BLOCKS)); 834 tree stmt; 835 836 stmt = build1 (LABEL_EXPR, void_type_node, dest); 837 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT); 838 uid = LABEL_DECL_UID (dest); 839 } 840 if (VEC_length (basic_block, ifun->cfg->x_label_to_block_map) 841 <= (unsigned int) uid) 842 return NULL; 843 return VEC_index (basic_block, ifun->cfg->x_label_to_block_map, uid); 844} 845 846/* Create edges for an abnormal goto statement at block BB. If FOR_CALL 847 is true, the source statement is a CALL_EXPR instead of a GOTO_EXPR. */ 848 849void 850make_abnormal_goto_edges (basic_block bb, bool for_call) 851{ 852 basic_block target_bb; 853 block_stmt_iterator bsi; 854 855 FOR_EACH_BB (target_bb) 856 for (bsi = bsi_start (target_bb); !bsi_end_p (bsi); bsi_next (&bsi)) 857 { 858 tree target = bsi_stmt (bsi); 859 860 if (TREE_CODE (target) != LABEL_EXPR) 861 break; 862 863 target = LABEL_EXPR_LABEL (target); 864 865 /* Make an edge to every label block that has been marked as a 866 potential target for a computed goto or a non-local goto. */ 867 if ((FORCED_LABEL (target) && !for_call) 868 || (DECL_NONLOCAL (target) && for_call)) 869 { 870 make_edge (bb, target_bb, EDGE_ABNORMAL); 871 break; 872 } 873 } 874} 875 876/* Create edges for a goto statement at block BB. */ 877 878static void 879make_goto_expr_edges (basic_block bb) 880{ 881 block_stmt_iterator last = bsi_last (bb); 882 tree goto_t = bsi_stmt (last); 883 884 /* A simple GOTO creates normal edges. */ 885 if (simple_goto_p (goto_t)) 886 { 887 tree dest = GOTO_DESTINATION (goto_t); 888 edge e = make_edge (bb, label_to_block (dest), EDGE_FALLTHRU); 889#ifdef USE_MAPPED_LOCATION 890 e->goto_locus = EXPR_LOCATION (goto_t); 891#else 892 e->goto_locus = EXPR_LOCUS (goto_t); 893#endif 894 bsi_remove (&last, true); 895 return; 896 } 897 898 /* A computed GOTO creates abnormal edges. */ 899 make_abnormal_goto_edges (bb, false); 900} 901 902 903/*--------------------------------------------------------------------------- 904 Flowgraph analysis 905---------------------------------------------------------------------------*/ 906 907/* Cleanup useless labels in basic blocks. This is something we wish 908 to do early because it allows us to group case labels before creating 909 the edges for the CFG, and it speeds up block statement iterators in 910 all passes later on. 911 We only run this pass once, running it more than once is probably not 912 profitable. */ 913 914/* A map from basic block index to the leading label of that block. */ 915static tree *label_for_bb; 916 917/* Callback for for_each_eh_region. Helper for cleanup_dead_labels. */ 918static void 919update_eh_label (struct eh_region *region) 920{ 921 tree old_label = get_eh_region_tree_label (region); 922 if (old_label) 923 { 924 tree new_label; 925 basic_block bb = label_to_block (old_label); 926 927 /* ??? After optimizing, there may be EH regions with labels 928 that have already been removed from the function body, so 929 there is no basic block for them. */ 930 if (! bb) 931 return; 932 933 new_label = label_for_bb[bb->index]; 934 set_eh_region_tree_label (region, new_label); 935 } 936} 937 938/* Given LABEL return the first label in the same basic block. */ 939static tree 940main_block_label (tree label) 941{ 942 basic_block bb = label_to_block (label); 943 944 /* label_to_block possibly inserted undefined label into the chain. */ 945 if (!label_for_bb[bb->index]) 946 label_for_bb[bb->index] = label; 947 return label_for_bb[bb->index]; 948} 949 950/* Cleanup redundant labels. This is a three-step process: 951 1) Find the leading label for each block. 952 2) Redirect all references to labels to the leading labels. 953 3) Cleanup all useless labels. */ 954 955void 956cleanup_dead_labels (void) 957{ 958 basic_block bb; 959 label_for_bb = XCNEWVEC (tree, last_basic_block); 960 961 /* Find a suitable label for each block. We use the first user-defined 962 label if there is one, or otherwise just the first label we see. */ 963 FOR_EACH_BB (bb) 964 { 965 block_stmt_iterator i; 966 967 for (i = bsi_start (bb); !bsi_end_p (i); bsi_next (&i)) 968 { 969 tree label, stmt = bsi_stmt (i); 970 971 if (TREE_CODE (stmt) != LABEL_EXPR) 972 break; 973 974 label = LABEL_EXPR_LABEL (stmt); 975 976 /* If we have not yet seen a label for the current block, 977 remember this one and see if there are more labels. */ 978 if (! label_for_bb[bb->index]) 979 { 980 label_for_bb[bb->index] = label; 981 continue; 982 } 983 984 /* If we did see a label for the current block already, but it 985 is an artificially created label, replace it if the current 986 label is a user defined label. */ 987 if (! DECL_ARTIFICIAL (label) 988 && DECL_ARTIFICIAL (label_for_bb[bb->index])) 989 { 990 label_for_bb[bb->index] = label; 991 break; 992 } 993 } 994 } 995 996 /* Now redirect all jumps/branches to the selected label. 997 First do so for each block ending in a control statement. */ 998 FOR_EACH_BB (bb) 999 { 1000 tree stmt = last_stmt (bb); 1001 if (!stmt) 1002 continue; 1003 1004 switch (TREE_CODE (stmt)) 1005 { 1006 case COND_EXPR: 1007 { 1008 tree true_branch, false_branch; 1009 1010 true_branch = COND_EXPR_THEN (stmt); 1011 false_branch = COND_EXPR_ELSE (stmt); 1012 1013 GOTO_DESTINATION (true_branch) 1014 = main_block_label (GOTO_DESTINATION (true_branch)); 1015 GOTO_DESTINATION (false_branch) 1016 = main_block_label (GOTO_DESTINATION (false_branch)); 1017 1018 break; 1019 } 1020 1021 case SWITCH_EXPR: 1022 { 1023 size_t i; 1024 tree vec = SWITCH_LABELS (stmt); 1025 size_t n = TREE_VEC_LENGTH (vec); 1026 1027 /* Replace all destination labels. */ 1028 for (i = 0; i < n; ++i) 1029 { 1030 tree elt = TREE_VEC_ELT (vec, i); 1031 tree label = main_block_label (CASE_LABEL (elt)); 1032 CASE_LABEL (elt) = label; 1033 } 1034 break; 1035 } 1036 1037 /* We have to handle GOTO_EXPRs until they're removed, and we don't 1038 remove them until after we've created the CFG edges. */ 1039 case GOTO_EXPR: 1040 if (! computed_goto_p (stmt)) 1041 { 1042 GOTO_DESTINATION (stmt) 1043 = main_block_label (GOTO_DESTINATION (stmt)); 1044 break; 1045 } 1046 1047 default: 1048 break; 1049 } 1050 } 1051 1052 for_each_eh_region (update_eh_label); 1053 1054/* APPLE LOCAL begin for-fsf-4_4 3274130 5295549 */ \ 1055 /* Finally, purge dead labels. All user-defined labels, labels that 1056 can be the target of non-local gotos, labels which have their 1057 address taken and labels which have attributes or alignment are 1058 preserved. */ 1059/* APPLE LOCAL end for-fsf-4_4 3274130 5295549 */ \ 1060 FOR_EACH_BB (bb) 1061 { 1062 block_stmt_iterator i; 1063 tree label_for_this_bb = label_for_bb[bb->index]; 1064 1065 if (! label_for_this_bb) 1066 continue; 1067 1068 for (i = bsi_start (bb); !bsi_end_p (i); ) 1069 { 1070 tree label, stmt = bsi_stmt (i); 1071 1072 if (TREE_CODE (stmt) != LABEL_EXPR) 1073 break; 1074 1075 label = LABEL_EXPR_LABEL (stmt); 1076 1077 if (label == label_for_this_bb 1078 || ! DECL_ARTIFICIAL (label) 1079/* APPLE LOCAL begin for-fsf-4_4 3274130 5295549 */ \ 1080 || DECL_ATTRIBUTES (label) 1081 || DECL_USER_ALIGN (label) 1082/* APPLE LOCAL end for-fsf-4_4 3274130 5295549 */ \ 1083 || DECL_NONLOCAL (label) 1084 || FORCED_LABEL (label)) 1085 bsi_next (&i); 1086 else 1087 bsi_remove (&i, true); 1088 } 1089 } 1090 1091 free (label_for_bb); 1092} 1093 1094/* Look for blocks ending in a multiway branch (a SWITCH_EXPR in GIMPLE), 1095 and scan the sorted vector of cases. Combine the ones jumping to the 1096 same label. 1097 Eg. three separate entries 1: 2: 3: become one entry 1..3: */ 1098 1099void 1100group_case_labels (void) 1101{ 1102 basic_block bb; 1103 1104 FOR_EACH_BB (bb) 1105 { 1106 tree stmt = last_stmt (bb); 1107 if (stmt && TREE_CODE (stmt) == SWITCH_EXPR) 1108 { 1109 tree labels = SWITCH_LABELS (stmt); 1110 int old_size = TREE_VEC_LENGTH (labels); 1111 int i, j, new_size = old_size; 1112 tree default_case = TREE_VEC_ELT (labels, old_size - 1); 1113 tree default_label; 1114 1115 /* The default label is always the last case in a switch 1116 statement after gimplification. */ 1117 default_label = CASE_LABEL (default_case); 1118 1119 /* Look for possible opportunities to merge cases. 1120 Ignore the last element of the label vector because it 1121 must be the default case. */ 1122 i = 0; 1123 while (i < old_size - 1) 1124 { 1125 tree base_case, base_label, base_high; 1126 base_case = TREE_VEC_ELT (labels, i); 1127 1128 gcc_assert (base_case); 1129 base_label = CASE_LABEL (base_case); 1130 1131 /* Discard cases that have the same destination as the 1132 default case. */ 1133 if (base_label == default_label) 1134 { 1135 TREE_VEC_ELT (labels, i) = NULL_TREE; 1136 i++; 1137 new_size--; 1138 continue; 1139 } 1140 1141 base_high = CASE_HIGH (base_case) ? 1142 CASE_HIGH (base_case) : CASE_LOW (base_case); 1143 i++; 1144 /* Try to merge case labels. Break out when we reach the end 1145 of the label vector or when we cannot merge the next case 1146 label with the current one. */ 1147 while (i < old_size - 1) 1148 { 1149 tree merge_case = TREE_VEC_ELT (labels, i); 1150 tree merge_label = CASE_LABEL (merge_case); 1151 tree t = int_const_binop (PLUS_EXPR, base_high, 1152 integer_one_node, 1); 1153 1154 /* Merge the cases if they jump to the same place, 1155 and their ranges are consecutive. */ 1156 if (merge_label == base_label 1157 && tree_int_cst_equal (CASE_LOW (merge_case), t)) 1158 { 1159 base_high = CASE_HIGH (merge_case) ? 1160 CASE_HIGH (merge_case) : CASE_LOW (merge_case); 1161 CASE_HIGH (base_case) = base_high; 1162 TREE_VEC_ELT (labels, i) = NULL_TREE; 1163 new_size--; 1164 i++; 1165 } 1166 else 1167 break; 1168 } 1169 } 1170 1171 /* Compress the case labels in the label vector, and adjust the 1172 length of the vector. */ 1173 for (i = 0, j = 0; i < new_size; i++) 1174 { 1175 while (! TREE_VEC_ELT (labels, j)) 1176 j++; 1177 TREE_VEC_ELT (labels, i) = TREE_VEC_ELT (labels, j++); 1178 } 1179 TREE_VEC_LENGTH (labels) = new_size; 1180 } 1181 } 1182} 1183 1184/* Checks whether we can merge block B into block A. */ 1185 1186static bool 1187tree_can_merge_blocks_p (basic_block a, basic_block b) 1188{ 1189 tree stmt; 1190 block_stmt_iterator bsi; 1191 tree phi; 1192 1193 if (!single_succ_p (a)) 1194 return false; 1195 1196 if (single_succ_edge (a)->flags & EDGE_ABNORMAL) 1197 return false; 1198 1199 if (single_succ (a) != b) 1200 return false; 1201 1202 if (!single_pred_p (b)) 1203 return false; 1204 1205 if (b == EXIT_BLOCK_PTR) 1206 return false; 1207 1208 /* If A ends by a statement causing exceptions or something similar, we 1209 cannot merge the blocks. */ 1210 stmt = last_stmt (a); 1211 if (stmt && stmt_ends_bb_p (stmt)) 1212 return false; 1213 1214 /* Do not allow a block with only a non-local label to be merged. */ 1215 if (stmt && TREE_CODE (stmt) == LABEL_EXPR 1216 && DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt))) 1217 return false; 1218 1219 /* It must be possible to eliminate all phi nodes in B. If ssa form 1220 is not up-to-date, we cannot eliminate any phis. */ 1221 phi = phi_nodes (b); 1222 if (phi) 1223 { 1224 if (need_ssa_update_p ()) 1225 return false; 1226 1227 for (; phi; phi = PHI_CHAIN (phi)) 1228 if (!is_gimple_reg (PHI_RESULT (phi)) 1229 && !may_propagate_copy (PHI_RESULT (phi), PHI_ARG_DEF (phi, 0))) 1230 return false; 1231 } 1232 1233 /* Do not remove user labels. */ 1234 for (bsi = bsi_start (b); !bsi_end_p (bsi); bsi_next (&bsi)) 1235 { 1236 stmt = bsi_stmt (bsi); 1237 if (TREE_CODE (stmt) != LABEL_EXPR) 1238 break; 1239 if (!DECL_ARTIFICIAL (LABEL_EXPR_LABEL (stmt))) 1240 return false; 1241 } 1242 1243 /* Protect the loop latches. */ 1244 if (current_loops 1245 && b->loop_father->latch == b) 1246 return false; 1247 1248 return true; 1249} 1250 1251/* Replaces all uses of NAME by VAL. */ 1252 1253void 1254replace_uses_by (tree name, tree val) 1255{ 1256 imm_use_iterator imm_iter; 1257 use_operand_p use; 1258 tree stmt; 1259 edge e; 1260 unsigned i; 1261 1262 1263 FOR_EACH_IMM_USE_STMT (stmt, imm_iter, name) 1264 { 1265 FOR_EACH_IMM_USE_ON_STMT (use, imm_iter) 1266 { 1267 replace_exp (use, val); 1268 1269 if (TREE_CODE (stmt) == PHI_NODE) 1270 { 1271 e = PHI_ARG_EDGE (stmt, PHI_ARG_INDEX_FROM_USE (use)); 1272 if (e->flags & EDGE_ABNORMAL) 1273 { 1274 /* This can only occur for virtual operands, since 1275 for the real ones SSA_NAME_OCCURS_IN_ABNORMAL_PHI (name)) 1276 would prevent replacement. */ 1277 gcc_assert (!is_gimple_reg (name)); 1278 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (val) = 1; 1279 } 1280 } 1281 } 1282 if (TREE_CODE (stmt) != PHI_NODE) 1283 { 1284 tree rhs; 1285 1286 fold_stmt_inplace (stmt); 1287 rhs = get_rhs (stmt); 1288 if (TREE_CODE (rhs) == ADDR_EXPR) 1289 recompute_tree_invariant_for_addr_expr (rhs); 1290 1291 maybe_clean_or_replace_eh_stmt (stmt, stmt); 1292 mark_new_vars_to_rename (stmt); 1293 } 1294 } 1295 1296 gcc_assert (num_imm_uses (name) == 0); 1297 1298 /* Also update the trees stored in loop structures. */ 1299 if (current_loops) 1300 { 1301 struct loop *loop; 1302 1303 for (i = 0; i < current_loops->num; i++) 1304 { 1305 loop = current_loops->parray[i]; 1306 if (loop) 1307 substitute_in_loop_info (loop, name, val); 1308 } 1309 } 1310} 1311 1312/* Merge block B into block A. */ 1313 1314static void 1315tree_merge_blocks (basic_block a, basic_block b) 1316{ 1317 block_stmt_iterator bsi; 1318 tree_stmt_iterator last; 1319 tree phi; 1320 1321 if (dump_file) 1322 fprintf (dump_file, "Merging blocks %d and %d\n", a->index, b->index); 1323 1324 /* Remove all single-valued PHI nodes from block B of the form 1325 V_i = PHI <V_j> by propagating V_j to all the uses of V_i. */ 1326 bsi = bsi_last (a); 1327 for (phi = phi_nodes (b); phi; phi = phi_nodes (b)) 1328 { 1329 tree def = PHI_RESULT (phi), use = PHI_ARG_DEF (phi, 0); 1330 tree copy; 1331 bool may_replace_uses = may_propagate_copy (def, use); 1332 1333 /* In case we have loops to care about, do not propagate arguments of 1334 loop closed ssa phi nodes. */ 1335 if (current_loops 1336 && is_gimple_reg (def) 1337 && TREE_CODE (use) == SSA_NAME 1338 && a->loop_father != b->loop_father) 1339 may_replace_uses = false; 1340 1341 if (!may_replace_uses) 1342 { 1343 gcc_assert (is_gimple_reg (def)); 1344 1345 /* Note that just emitting the copies is fine -- there is no problem 1346 with ordering of phi nodes. This is because A is the single 1347 predecessor of B, therefore results of the phi nodes cannot 1348 appear as arguments of the phi nodes. */ 1349 copy = build2 (MODIFY_EXPR, void_type_node, def, use); 1350 bsi_insert_after (&bsi, copy, BSI_NEW_STMT); 1351 SET_PHI_RESULT (phi, NULL_TREE); 1352 SSA_NAME_DEF_STMT (def) = copy; 1353 } 1354 else 1355 replace_uses_by (def, use); 1356 1357 remove_phi_node (phi, NULL); 1358 } 1359 1360 /* Ensure that B follows A. */ 1361 move_block_after (b, a); 1362 1363 gcc_assert (single_succ_edge (a)->flags & EDGE_FALLTHRU); 1364 gcc_assert (!last_stmt (a) || !stmt_ends_bb_p (last_stmt (a))); 1365 1366 /* Remove labels from B and set bb_for_stmt to A for other statements. */ 1367 for (bsi = bsi_start (b); !bsi_end_p (bsi);) 1368 { 1369 if (TREE_CODE (bsi_stmt (bsi)) == LABEL_EXPR) 1370 { 1371 tree label = bsi_stmt (bsi); 1372 1373 bsi_remove (&bsi, false); 1374 /* Now that we can thread computed gotos, we might have 1375 a situation where we have a forced label in block B 1376 However, the label at the start of block B might still be 1377 used in other ways (think about the runtime checking for 1378 Fortran assigned gotos). So we can not just delete the 1379 label. Instead we move the label to the start of block A. */ 1380 if (FORCED_LABEL (LABEL_EXPR_LABEL (label))) 1381 { 1382 block_stmt_iterator dest_bsi = bsi_start (a); 1383 bsi_insert_before (&dest_bsi, label, BSI_NEW_STMT); 1384 } 1385 } 1386 else 1387 { 1388 change_bb_for_stmt (bsi_stmt (bsi), a); 1389 bsi_next (&bsi); 1390 } 1391 } 1392 1393 /* Merge the chains. */ 1394 last = tsi_last (a->stmt_list); 1395 tsi_link_after (&last, b->stmt_list, TSI_NEW_STMT); 1396 b->stmt_list = NULL; 1397} 1398 1399 1400/* Return the one of two successors of BB that is not reachable by a 1401 reached by a complex edge, if there is one. Else, return BB. We use 1402 this in optimizations that use post-dominators for their heuristics, 1403 to catch the cases in C++ where function calls are involved. */ 1404 1405basic_block 1406single_noncomplex_succ (basic_block bb) 1407{ 1408 edge e0, e1; 1409 if (EDGE_COUNT (bb->succs) != 2) 1410 return bb; 1411 1412 e0 = EDGE_SUCC (bb, 0); 1413 e1 = EDGE_SUCC (bb, 1); 1414 if (e0->flags & EDGE_COMPLEX) 1415 return e1->dest; 1416 if (e1->flags & EDGE_COMPLEX) 1417 return e0->dest; 1418 1419 return bb; 1420} 1421 1422 1423/* Walk the function tree removing unnecessary statements. 1424 1425 * Empty statement nodes are removed 1426 1427 * Unnecessary TRY_FINALLY and TRY_CATCH blocks are removed 1428 1429 * Unnecessary COND_EXPRs are removed 1430 1431 * Some unnecessary BIND_EXPRs are removed 1432 1433 Clearly more work could be done. The trick is doing the analysis 1434 and removal fast enough to be a net improvement in compile times. 1435 1436 Note that when we remove a control structure such as a COND_EXPR 1437 BIND_EXPR, or TRY block, we will need to repeat this optimization pass 1438 to ensure we eliminate all the useless code. */ 1439 1440struct rus_data 1441{ 1442 tree *last_goto; 1443 bool repeat; 1444 bool may_throw; 1445 bool may_branch; 1446 bool has_label; 1447}; 1448 1449static void remove_useless_stmts_1 (tree *, struct rus_data *); 1450 1451static bool 1452remove_useless_stmts_warn_notreached (tree stmt) 1453{ 1454 if (EXPR_HAS_LOCATION (stmt)) 1455 { 1456 location_t loc = EXPR_LOCATION (stmt); 1457 if (LOCATION_LINE (loc) > 0) 1458 { 1459 warning (0, "%Hwill never be executed", &loc); 1460 return true; 1461 } 1462 } 1463 1464 switch (TREE_CODE (stmt)) 1465 { 1466 case STATEMENT_LIST: 1467 { 1468 tree_stmt_iterator i; 1469 for (i = tsi_start (stmt); !tsi_end_p (i); tsi_next (&i)) 1470 if (remove_useless_stmts_warn_notreached (tsi_stmt (i))) 1471 return true; 1472 } 1473 break; 1474 1475 case COND_EXPR: 1476 if (remove_useless_stmts_warn_notreached (COND_EXPR_COND (stmt))) 1477 return true; 1478 if (remove_useless_stmts_warn_notreached (COND_EXPR_THEN (stmt))) 1479 return true; 1480 if (remove_useless_stmts_warn_notreached (COND_EXPR_ELSE (stmt))) 1481 return true; 1482 break; 1483 1484 case TRY_FINALLY_EXPR: 1485 case TRY_CATCH_EXPR: 1486 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt, 0))) 1487 return true; 1488 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt, 1))) 1489 return true; 1490 break; 1491 1492 case CATCH_EXPR: 1493 return remove_useless_stmts_warn_notreached (CATCH_BODY (stmt)); 1494 case EH_FILTER_EXPR: 1495 return remove_useless_stmts_warn_notreached (EH_FILTER_FAILURE (stmt)); 1496 case BIND_EXPR: 1497 return remove_useless_stmts_warn_notreached (BIND_EXPR_BLOCK (stmt)); 1498 1499 default: 1500 /* Not a live container. */ 1501 break; 1502 } 1503 1504 return false; 1505} 1506 1507static void 1508remove_useless_stmts_cond (tree *stmt_p, struct rus_data *data) 1509{ 1510 tree then_clause, else_clause, cond; 1511 bool save_has_label, then_has_label, else_has_label; 1512 1513 save_has_label = data->has_label; 1514 data->has_label = false; 1515 data->last_goto = NULL; 1516 1517 remove_useless_stmts_1 (&COND_EXPR_THEN (*stmt_p), data); 1518 1519 then_has_label = data->has_label; 1520 data->has_label = false; 1521 data->last_goto = NULL; 1522 1523 remove_useless_stmts_1 (&COND_EXPR_ELSE (*stmt_p), data); 1524 1525 else_has_label = data->has_label; 1526 data->has_label = save_has_label | then_has_label | else_has_label; 1527 1528 then_clause = COND_EXPR_THEN (*stmt_p); 1529 else_clause = COND_EXPR_ELSE (*stmt_p); 1530 cond = fold (COND_EXPR_COND (*stmt_p)); 1531 1532 /* If neither arm does anything at all, we can remove the whole IF. */ 1533 if (!TREE_SIDE_EFFECTS (then_clause) && !TREE_SIDE_EFFECTS (else_clause)) 1534 { 1535 *stmt_p = build_empty_stmt (); 1536 data->repeat = true; 1537 } 1538 1539 /* If there are no reachable statements in an arm, then we can 1540 zap the entire conditional. */ 1541 else if (integer_nonzerop (cond) && !else_has_label) 1542 { 1543 if (warn_notreached) 1544 remove_useless_stmts_warn_notreached (else_clause); 1545 *stmt_p = then_clause; 1546 data->repeat = true; 1547 } 1548 else if (integer_zerop (cond) && !then_has_label) 1549 { 1550 if (warn_notreached) 1551 remove_useless_stmts_warn_notreached (then_clause); 1552 *stmt_p = else_clause; 1553 data->repeat = true; 1554 } 1555 1556 /* Check a couple of simple things on then/else with single stmts. */ 1557 else 1558 { 1559 tree then_stmt = expr_only (then_clause); 1560 tree else_stmt = expr_only (else_clause); 1561 1562 /* Notice branches to a common destination. */ 1563 if (then_stmt && else_stmt 1564 && TREE_CODE (then_stmt) == GOTO_EXPR 1565 && TREE_CODE (else_stmt) == GOTO_EXPR 1566 && (GOTO_DESTINATION (then_stmt) == GOTO_DESTINATION (else_stmt))) 1567 { 1568 *stmt_p = then_stmt; 1569 data->repeat = true; 1570 } 1571 1572 /* If the THEN/ELSE clause merely assigns a value to a variable or 1573 parameter which is already known to contain that value, then 1574 remove the useless THEN/ELSE clause. */ 1575 else if (TREE_CODE (cond) == VAR_DECL || TREE_CODE (cond) == PARM_DECL) 1576 { 1577 if (else_stmt 1578 && TREE_CODE (else_stmt) == MODIFY_EXPR 1579 && TREE_OPERAND (else_stmt, 0) == cond 1580 && integer_zerop (TREE_OPERAND (else_stmt, 1))) 1581 COND_EXPR_ELSE (*stmt_p) = alloc_stmt_list (); 1582 } 1583 else if ((TREE_CODE (cond) == EQ_EXPR || TREE_CODE (cond) == NE_EXPR) 1584 && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL 1585 || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL) 1586 && TREE_CONSTANT (TREE_OPERAND (cond, 1))) 1587 { 1588 tree stmt = (TREE_CODE (cond) == EQ_EXPR 1589 ? then_stmt : else_stmt); 1590 tree *location = (TREE_CODE (cond) == EQ_EXPR 1591 ? &COND_EXPR_THEN (*stmt_p) 1592 : &COND_EXPR_ELSE (*stmt_p)); 1593 1594 if (stmt 1595 && TREE_CODE (stmt) == MODIFY_EXPR 1596 && TREE_OPERAND (stmt, 0) == TREE_OPERAND (cond, 0) 1597 && TREE_OPERAND (stmt, 1) == TREE_OPERAND (cond, 1)) 1598 *location = alloc_stmt_list (); 1599 } 1600 } 1601 1602 /* Protect GOTOs in the arm of COND_EXPRs from being removed. They 1603 would be re-introduced during lowering. */ 1604 data->last_goto = NULL; 1605} 1606 1607 1608static void 1609remove_useless_stmts_tf (tree *stmt_p, struct rus_data *data) 1610{ 1611 bool save_may_branch, save_may_throw; 1612 bool this_may_branch, this_may_throw; 1613 1614 /* Collect may_branch and may_throw information for the body only. */ 1615 save_may_branch = data->may_branch; 1616 save_may_throw = data->may_throw; 1617 data->may_branch = false; 1618 data->may_throw = false; 1619 data->last_goto = NULL; 1620 1621 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 0), data); 1622 1623 this_may_branch = data->may_branch; 1624 this_may_throw = data->may_throw; 1625 data->may_branch |= save_may_branch; 1626 data->may_throw |= save_may_throw; 1627 data->last_goto = NULL; 1628 1629 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 1), data); 1630 1631 /* If the body is empty, then we can emit the FINALLY block without 1632 the enclosing TRY_FINALLY_EXPR. */ 1633 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 0))) 1634 { 1635 *stmt_p = TREE_OPERAND (*stmt_p, 1); 1636 data->repeat = true; 1637 } 1638 1639 /* If the handler is empty, then we can emit the TRY block without 1640 the enclosing TRY_FINALLY_EXPR. */ 1641 else if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 1))) 1642 { 1643 *stmt_p = TREE_OPERAND (*stmt_p, 0); 1644 data->repeat = true; 1645 } 1646 1647 /* If the body neither throws, nor branches, then we can safely 1648 string the TRY and FINALLY blocks together. */ 1649 else if (!this_may_branch && !this_may_throw) 1650 { 1651 tree stmt = *stmt_p; 1652 *stmt_p = TREE_OPERAND (stmt, 0); 1653 append_to_statement_list (TREE_OPERAND (stmt, 1), stmt_p); 1654 data->repeat = true; 1655 } 1656} 1657 1658 1659static void 1660remove_useless_stmts_tc (tree *stmt_p, struct rus_data *data) 1661{ 1662 bool save_may_throw, this_may_throw; 1663 tree_stmt_iterator i; 1664 tree stmt; 1665 1666 /* Collect may_throw information for the body only. */ 1667 save_may_throw = data->may_throw; 1668 data->may_throw = false; 1669 data->last_goto = NULL; 1670 1671 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 0), data); 1672 1673 this_may_throw = data->may_throw; 1674 data->may_throw = save_may_throw; 1675 1676 /* If the body cannot throw, then we can drop the entire TRY_CATCH_EXPR. */ 1677 if (!this_may_throw) 1678 { 1679 if (warn_notreached) 1680 remove_useless_stmts_warn_notreached (TREE_OPERAND (*stmt_p, 1)); 1681 *stmt_p = TREE_OPERAND (*stmt_p, 0); 1682 data->repeat = true; 1683 return; 1684 } 1685 1686 /* Process the catch clause specially. We may be able to tell that 1687 no exceptions propagate past this point. */ 1688 1689 this_may_throw = true; 1690 i = tsi_start (TREE_OPERAND (*stmt_p, 1)); 1691 stmt = tsi_stmt (i); 1692 data->last_goto = NULL; 1693 1694 switch (TREE_CODE (stmt)) 1695 { 1696 case CATCH_EXPR: 1697 for (; !tsi_end_p (i); tsi_next (&i)) 1698 { 1699 stmt = tsi_stmt (i); 1700 /* If we catch all exceptions, then the body does not 1701 propagate exceptions past this point. */ 1702 if (CATCH_TYPES (stmt) == NULL) 1703 this_may_throw = false; 1704 data->last_goto = NULL; 1705 remove_useless_stmts_1 (&CATCH_BODY (stmt), data); 1706 } 1707 break; 1708 1709 case EH_FILTER_EXPR: 1710 if (EH_FILTER_MUST_NOT_THROW (stmt)) 1711 this_may_throw = false; 1712 else if (EH_FILTER_TYPES (stmt) == NULL) 1713 this_may_throw = false; 1714 remove_useless_stmts_1 (&EH_FILTER_FAILURE (stmt), data); 1715 break; 1716 1717 default: 1718 /* Otherwise this is a cleanup. */ 1719 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 1), data); 1720 1721 /* If the cleanup is empty, then we can emit the TRY block without 1722 the enclosing TRY_CATCH_EXPR. */ 1723 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 1))) 1724 { 1725 *stmt_p = TREE_OPERAND (*stmt_p, 0); 1726 data->repeat = true; 1727 } 1728 break; 1729 } 1730 data->may_throw |= this_may_throw; 1731} 1732 1733 1734static void 1735remove_useless_stmts_bind (tree *stmt_p, struct rus_data *data) 1736{ 1737 tree block; 1738 1739 /* First remove anything underneath the BIND_EXPR. */ 1740 remove_useless_stmts_1 (&BIND_EXPR_BODY (*stmt_p), data); 1741 1742 /* If the BIND_EXPR has no variables, then we can pull everything 1743 up one level and remove the BIND_EXPR, unless this is the toplevel 1744 BIND_EXPR for the current function or an inlined function. 1745 1746 When this situation occurs we will want to apply this 1747 optimization again. */ 1748 block = BIND_EXPR_BLOCK (*stmt_p); 1749 if (BIND_EXPR_VARS (*stmt_p) == NULL_TREE 1750 && *stmt_p != DECL_SAVED_TREE (current_function_decl) 1751 && (! block 1752 || ! BLOCK_ABSTRACT_ORIGIN (block) 1753 || (TREE_CODE (BLOCK_ABSTRACT_ORIGIN (block)) 1754 != FUNCTION_DECL))) 1755 { 1756 *stmt_p = BIND_EXPR_BODY (*stmt_p); 1757 data->repeat = true; 1758 } 1759} 1760 1761 1762static void 1763remove_useless_stmts_goto (tree *stmt_p, struct rus_data *data) 1764{ 1765 tree dest = GOTO_DESTINATION (*stmt_p); 1766 1767 data->may_branch = true; 1768 data->last_goto = NULL; 1769 1770 /* Record the last goto expr, so that we can delete it if unnecessary. */ 1771 if (TREE_CODE (dest) == LABEL_DECL) 1772 data->last_goto = stmt_p; 1773} 1774 1775 1776static void 1777remove_useless_stmts_label (tree *stmt_p, struct rus_data *data) 1778{ 1779 tree label = LABEL_EXPR_LABEL (*stmt_p); 1780 1781 data->has_label = true; 1782 1783 /* We do want to jump across non-local label receiver code. */ 1784 if (DECL_NONLOCAL (label)) 1785 data->last_goto = NULL; 1786 1787 else if (data->last_goto && GOTO_DESTINATION (*data->last_goto) == label) 1788 { 1789 *data->last_goto = build_empty_stmt (); 1790 data->repeat = true; 1791 } 1792 1793 /* ??? Add something here to delete unused labels. */ 1794} 1795 1796 1797/* If the function is "const" or "pure", then clear TREE_SIDE_EFFECTS on its 1798 decl. This allows us to eliminate redundant or useless 1799 calls to "const" functions. 1800 1801 Gimplifier already does the same operation, but we may notice functions 1802 being const and pure once their calls has been gimplified, so we need 1803 to update the flag. */ 1804 1805static void 1806update_call_expr_flags (tree call) 1807{ 1808 tree decl = get_callee_fndecl (call); 1809 if (!decl) 1810 return; 1811 if (call_expr_flags (call) & (ECF_CONST | ECF_PURE)) 1812 TREE_SIDE_EFFECTS (call) = 0; 1813 if (TREE_NOTHROW (decl)) 1814 TREE_NOTHROW (call) = 1; 1815} 1816 1817 1818/* T is CALL_EXPR. Set current_function_calls_* flags. */ 1819 1820void 1821notice_special_calls (tree t) 1822{ 1823 int flags = call_expr_flags (t); 1824 1825 if (flags & ECF_MAY_BE_ALLOCA) 1826 current_function_calls_alloca = true; 1827 if (flags & ECF_RETURNS_TWICE) 1828 current_function_calls_setjmp = true; 1829} 1830 1831 1832/* Clear flags set by notice_special_calls. Used by dead code removal 1833 to update the flags. */ 1834 1835void 1836clear_special_calls (void) 1837{ 1838 current_function_calls_alloca = false; 1839 current_function_calls_setjmp = false; 1840} 1841 1842 1843static void 1844remove_useless_stmts_1 (tree *tp, struct rus_data *data) 1845{ 1846 tree t = *tp, op; 1847 1848 switch (TREE_CODE (t)) 1849 { 1850 case COND_EXPR: 1851 remove_useless_stmts_cond (tp, data); 1852 break; 1853 1854 case TRY_FINALLY_EXPR: 1855 remove_useless_stmts_tf (tp, data); 1856 break; 1857 1858 case TRY_CATCH_EXPR: 1859 remove_useless_stmts_tc (tp, data); 1860 break; 1861 1862 case BIND_EXPR: 1863 remove_useless_stmts_bind (tp, data); 1864 break; 1865 1866 case GOTO_EXPR: 1867 remove_useless_stmts_goto (tp, data); 1868 break; 1869 1870 case LABEL_EXPR: 1871 remove_useless_stmts_label (tp, data); 1872 break; 1873 1874 case RETURN_EXPR: 1875 fold_stmt (tp); 1876 data->last_goto = NULL; 1877 data->may_branch = true; 1878 break; 1879 1880 case CALL_EXPR: 1881 fold_stmt (tp); 1882 data->last_goto = NULL; 1883 notice_special_calls (t); 1884 update_call_expr_flags (t); 1885 if (tree_could_throw_p (t)) 1886 data->may_throw = true; 1887 break; 1888 1889 case MODIFY_EXPR: 1890 data->last_goto = NULL; 1891 fold_stmt (tp); 1892 op = get_call_expr_in (t); 1893 if (op) 1894 { 1895 update_call_expr_flags (op); 1896 notice_special_calls (op); 1897 } 1898 if (tree_could_throw_p (t)) 1899 data->may_throw = true; 1900 break; 1901 1902 case STATEMENT_LIST: 1903 { 1904 tree_stmt_iterator i = tsi_start (t); 1905 while (!tsi_end_p (i)) 1906 { 1907 t = tsi_stmt (i); 1908 if (IS_EMPTY_STMT (t)) 1909 { 1910 tsi_delink (&i); 1911 continue; 1912 } 1913 1914 remove_useless_stmts_1 (tsi_stmt_ptr (i), data); 1915 1916 t = tsi_stmt (i); 1917 if (TREE_CODE (t) == STATEMENT_LIST) 1918 { 1919 tsi_link_before (&i, t, TSI_SAME_STMT); 1920 tsi_delink (&i); 1921 } 1922 else 1923 tsi_next (&i); 1924 } 1925 } 1926 break; 1927 case ASM_EXPR: 1928 fold_stmt (tp); 1929 data->last_goto = NULL; 1930 break; 1931 1932 default: 1933 data->last_goto = NULL; 1934 break; 1935 } 1936} 1937 1938static unsigned int 1939remove_useless_stmts (void) 1940{ 1941 struct rus_data data; 1942 1943 clear_special_calls (); 1944 1945 do 1946 { 1947 memset (&data, 0, sizeof (data)); 1948 remove_useless_stmts_1 (&DECL_SAVED_TREE (current_function_decl), &data); 1949 } 1950 while (data.repeat); 1951 return 0; 1952} 1953 1954 1955struct tree_opt_pass pass_remove_useless_stmts = 1956{ 1957 "useless", /* name */ 1958 NULL, /* gate */ 1959 remove_useless_stmts, /* execute */ 1960 NULL, /* sub */ 1961 NULL, /* next */ 1962 0, /* static_pass_number */ 1963 0, /* tv_id */ 1964 PROP_gimple_any, /* properties_required */ 1965 0, /* properties_provided */ 1966 0, /* properties_destroyed */ 1967 0, /* todo_flags_start */ 1968 TODO_dump_func, /* todo_flags_finish */ 1969 0 /* letter */ 1970}; 1971 1972/* Remove PHI nodes associated with basic block BB and all edges out of BB. */ 1973 1974static void 1975remove_phi_nodes_and_edges_for_unreachable_block (basic_block bb) 1976{ 1977 tree phi; 1978 1979 /* Since this block is no longer reachable, we can just delete all 1980 of its PHI nodes. */ 1981 phi = phi_nodes (bb); 1982 while (phi) 1983 { 1984 tree next = PHI_CHAIN (phi); 1985 remove_phi_node (phi, NULL_TREE); 1986 phi = next; 1987 } 1988 1989 /* Remove edges to BB's successors. */ 1990 while (EDGE_COUNT (bb->succs) > 0) 1991 remove_edge (EDGE_SUCC (bb, 0)); 1992} 1993 1994 1995/* Remove statements of basic block BB. */ 1996 1997static void 1998remove_bb (basic_block bb) 1999{ 2000 block_stmt_iterator i; 2001#ifdef USE_MAPPED_LOCATION 2002 source_location loc = UNKNOWN_LOCATION; 2003#else 2004 source_locus loc = 0; 2005#endif 2006 2007 if (dump_file) 2008 { 2009 fprintf (dump_file, "Removing basic block %d\n", bb->index); 2010 if (dump_flags & TDF_DETAILS) 2011 { 2012 dump_bb (bb, dump_file, 0); 2013 fprintf (dump_file, "\n"); 2014 } 2015 } 2016 2017 /* If we remove the header or the latch of a loop, mark the loop for 2018 removal by setting its header and latch to NULL. */ 2019 if (current_loops) 2020 { 2021 struct loop *loop = bb->loop_father; 2022 2023 if (loop->latch == bb 2024 || loop->header == bb) 2025 { 2026 loop->latch = NULL; 2027 loop->header = NULL; 2028 2029 /* Also clean up the information associated with the loop. Updating 2030 it would waste time. More importantly, it may refer to ssa 2031 names that were defined in other removed basic block -- these 2032 ssa names are now removed and invalid. */ 2033 free_numbers_of_iterations_estimates_loop (loop); 2034 } 2035 } 2036 2037 /* Remove all the instructions in the block. */ 2038 for (i = bsi_start (bb); !bsi_end_p (i);) 2039 { 2040 tree stmt = bsi_stmt (i); 2041 if (TREE_CODE (stmt) == LABEL_EXPR 2042 && (FORCED_LABEL (LABEL_EXPR_LABEL (stmt)) 2043 || DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)))) 2044 { 2045 basic_block new_bb; 2046 block_stmt_iterator new_bsi; 2047 2048 /* A non-reachable non-local label may still be referenced. 2049 But it no longer needs to carry the extra semantics of 2050 non-locality. */ 2051 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt))) 2052 { 2053 DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)) = 0; 2054 FORCED_LABEL (LABEL_EXPR_LABEL (stmt)) = 1; 2055 } 2056 2057 new_bb = bb->prev_bb; 2058 new_bsi = bsi_start (new_bb); 2059 bsi_remove (&i, false); 2060 bsi_insert_before (&new_bsi, stmt, BSI_NEW_STMT); 2061 } 2062 else 2063 { 2064 /* Release SSA definitions if we are in SSA. Note that we 2065 may be called when not in SSA. For example, 2066 final_cleanup calls this function via 2067 cleanup_tree_cfg. */ 2068 if (in_ssa_p) 2069 release_defs (stmt); 2070 2071 bsi_remove (&i, true); 2072 } 2073 2074 /* Don't warn for removed gotos. Gotos are often removed due to 2075 jump threading, thus resulting in bogus warnings. Not great, 2076 since this way we lose warnings for gotos in the original 2077 program that are indeed unreachable. */ 2078 if (TREE_CODE (stmt) != GOTO_EXPR && EXPR_HAS_LOCATION (stmt) && !loc) 2079 { 2080#ifdef USE_MAPPED_LOCATION 2081 if (EXPR_HAS_LOCATION (stmt)) 2082 loc = EXPR_LOCATION (stmt); 2083#else 2084 source_locus t; 2085 t = EXPR_LOCUS (stmt); 2086 if (t && LOCATION_LINE (*t) > 0) 2087 loc = t; 2088#endif 2089 } 2090 } 2091 2092 /* If requested, give a warning that the first statement in the 2093 block is unreachable. We walk statements backwards in the 2094 loop above, so the last statement we process is the first statement 2095 in the block. */ 2096#ifdef USE_MAPPED_LOCATION 2097 if (loc > BUILTINS_LOCATION) 2098 warning (OPT_Wunreachable_code, "%Hwill never be executed", &loc); 2099#else 2100 if (loc) 2101 warning (OPT_Wunreachable_code, "%Hwill never be executed", loc); 2102#endif 2103 2104 remove_phi_nodes_and_edges_for_unreachable_block (bb); 2105} 2106 2107 2108/* Given a basic block BB ending with COND_EXPR or SWITCH_EXPR, and a 2109 predicate VAL, return the edge that will be taken out of the block. 2110 If VAL does not match a unique edge, NULL is returned. */ 2111 2112edge 2113find_taken_edge (basic_block bb, tree val) 2114{ 2115 tree stmt; 2116 2117 stmt = last_stmt (bb); 2118 2119 gcc_assert (stmt); 2120 gcc_assert (is_ctrl_stmt (stmt)); 2121 gcc_assert (val); 2122 2123 if (! is_gimple_min_invariant (val)) 2124 return NULL; 2125 2126 if (TREE_CODE (stmt) == COND_EXPR) 2127 return find_taken_edge_cond_expr (bb, val); 2128 2129 if (TREE_CODE (stmt) == SWITCH_EXPR) 2130 return find_taken_edge_switch_expr (bb, val); 2131 2132 if (computed_goto_p (stmt)) 2133 { 2134 /* Only optimize if the argument is a label, if the argument is 2135 not a label then we can not construct a proper CFG. 2136 2137 It may be the case that we only need to allow the LABEL_REF to 2138 appear inside an ADDR_EXPR, but we also allow the LABEL_REF to 2139 appear inside a LABEL_EXPR just to be safe. */ 2140 if ((TREE_CODE (val) == ADDR_EXPR || TREE_CODE (val) == LABEL_EXPR) 2141 && TREE_CODE (TREE_OPERAND (val, 0)) == LABEL_DECL) 2142 return find_taken_edge_computed_goto (bb, TREE_OPERAND (val, 0)); 2143 return NULL; 2144 } 2145 2146 gcc_unreachable (); 2147} 2148 2149/* Given a constant value VAL and the entry block BB to a GOTO_EXPR 2150 statement, determine which of the outgoing edges will be taken out of the 2151 block. Return NULL if either edge may be taken. */ 2152 2153static edge 2154find_taken_edge_computed_goto (basic_block bb, tree val) 2155{ 2156 basic_block dest; 2157 edge e = NULL; 2158 2159 dest = label_to_block (val); 2160 if (dest) 2161 { 2162 e = find_edge (bb, dest); 2163 gcc_assert (e != NULL); 2164 } 2165 2166 return e; 2167} 2168 2169/* Given a constant value VAL and the entry block BB to a COND_EXPR 2170 statement, determine which of the two edges will be taken out of the 2171 block. Return NULL if either edge may be taken. */ 2172 2173static edge 2174find_taken_edge_cond_expr (basic_block bb, tree val) 2175{ 2176 edge true_edge, false_edge; 2177 2178 extract_true_false_edges_from_block (bb, &true_edge, &false_edge); 2179 2180 gcc_assert (TREE_CODE (val) == INTEGER_CST); 2181 return (zero_p (val) ? false_edge : true_edge); 2182} 2183 2184/* Given an INTEGER_CST VAL and the entry block BB to a SWITCH_EXPR 2185 statement, determine which edge will be taken out of the block. Return 2186 NULL if any edge may be taken. */ 2187 2188static edge 2189find_taken_edge_switch_expr (basic_block bb, tree val) 2190{ 2191 tree switch_expr, taken_case; 2192 basic_block dest_bb; 2193 edge e; 2194 2195 switch_expr = last_stmt (bb); 2196 taken_case = find_case_label_for_value (switch_expr, val); 2197 dest_bb = label_to_block (CASE_LABEL (taken_case)); 2198 2199 e = find_edge (bb, dest_bb); 2200 gcc_assert (e); 2201 return e; 2202} 2203 2204 2205/* Return the CASE_LABEL_EXPR that SWITCH_EXPR will take for VAL. 2206 We can make optimal use here of the fact that the case labels are 2207 sorted: We can do a binary search for a case matching VAL. */ 2208 2209static tree 2210find_case_label_for_value (tree switch_expr, tree val) 2211{ 2212 tree vec = SWITCH_LABELS (switch_expr); 2213 size_t low, high, n = TREE_VEC_LENGTH (vec); 2214 tree default_case = TREE_VEC_ELT (vec, n - 1); 2215 2216 for (low = -1, high = n - 1; high - low > 1; ) 2217 { 2218 size_t i = (high + low) / 2; 2219 tree t = TREE_VEC_ELT (vec, i); 2220 int cmp; 2221 2222 /* Cache the result of comparing CASE_LOW and val. */ 2223 cmp = tree_int_cst_compare (CASE_LOW (t), val); 2224 2225 if (cmp > 0) 2226 high = i; 2227 else 2228 low = i; 2229 2230 if (CASE_HIGH (t) == NULL) 2231 { 2232 /* A singe-valued case label. */ 2233 if (cmp == 0) 2234 return t; 2235 } 2236 else 2237 { 2238 /* A case range. We can only handle integer ranges. */ 2239 if (cmp <= 0 && tree_int_cst_compare (CASE_HIGH (t), val) >= 0) 2240 return t; 2241 } 2242 } 2243 2244 return default_case; 2245} 2246 2247 2248 2249 2250/*--------------------------------------------------------------------------- 2251 Debugging functions 2252---------------------------------------------------------------------------*/ 2253 2254/* Dump tree-specific information of block BB to file OUTF. */ 2255 2256void 2257tree_dump_bb (basic_block bb, FILE *outf, int indent) 2258{ 2259 dump_generic_bb (outf, bb, indent, TDF_VOPS); 2260} 2261 2262 2263/* Dump a basic block on stderr. */ 2264 2265void 2266debug_tree_bb (basic_block bb) 2267{ 2268 dump_bb (bb, stderr, 0); 2269} 2270 2271 2272/* Dump basic block with index N on stderr. */ 2273 2274basic_block 2275debug_tree_bb_n (int n) 2276{ 2277 debug_tree_bb (BASIC_BLOCK (n)); 2278 return BASIC_BLOCK (n); 2279} 2280 2281 2282/* Dump the CFG on stderr. 2283 2284 FLAGS are the same used by the tree dumping functions 2285 (see TDF_* in tree-pass.h). */ 2286 2287void 2288debug_tree_cfg (int flags) 2289{ 2290 dump_tree_cfg (stderr, flags); 2291} 2292 2293 2294/* Dump the program showing basic block boundaries on the given FILE. 2295 2296 FLAGS are the same used by the tree dumping functions (see TDF_* in 2297 tree.h). */ 2298 2299void 2300dump_tree_cfg (FILE *file, int flags) 2301{ 2302 if (flags & TDF_DETAILS) 2303 { 2304 const char *funcname 2305 = lang_hooks.decl_printable_name (current_function_decl, 2); 2306 2307 fputc ('\n', file); 2308 fprintf (file, ";; Function %s\n\n", funcname); 2309 fprintf (file, ";; \n%d basic blocks, %d edges, last basic block %d.\n\n", 2310 n_basic_blocks, n_edges, last_basic_block); 2311 2312 brief_dump_cfg (file); 2313 fprintf (file, "\n"); 2314 } 2315 2316 if (flags & TDF_STATS) 2317 dump_cfg_stats (file); 2318 2319 dump_function_to_file (current_function_decl, file, flags | TDF_BLOCKS); 2320} 2321 2322 2323/* Dump CFG statistics on FILE. */ 2324 2325void 2326dump_cfg_stats (FILE *file) 2327{ 2328 static long max_num_merged_labels = 0; 2329 unsigned long size, total = 0; 2330 long num_edges; 2331 basic_block bb; 2332 const char * const fmt_str = "%-30s%-13s%12s\n"; 2333 const char * const fmt_str_1 = "%-30s%13d%11lu%c\n"; 2334 const char * const fmt_str_2 = "%-30s%13ld%11lu%c\n"; 2335 const char * const fmt_str_3 = "%-43s%11lu%c\n"; 2336 const char *funcname 2337 = lang_hooks.decl_printable_name (current_function_decl, 2); 2338 2339 2340 fprintf (file, "\nCFG Statistics for %s\n\n", funcname); 2341 2342 fprintf (file, "---------------------------------------------------------\n"); 2343 fprintf (file, fmt_str, "", " Number of ", "Memory"); 2344 fprintf (file, fmt_str, "", " instances ", "used "); 2345 fprintf (file, "---------------------------------------------------------\n"); 2346 2347 size = n_basic_blocks * sizeof (struct basic_block_def); 2348 total += size; 2349 fprintf (file, fmt_str_1, "Basic blocks", n_basic_blocks, 2350 SCALE (size), LABEL (size)); 2351 2352 num_edges = 0; 2353 FOR_EACH_BB (bb) 2354 num_edges += EDGE_COUNT (bb->succs); 2355 size = num_edges * sizeof (struct edge_def); 2356 total += size; 2357 fprintf (file, fmt_str_2, "Edges", num_edges, SCALE (size), LABEL (size)); 2358 2359 fprintf (file, "---------------------------------------------------------\n"); 2360 fprintf (file, fmt_str_3, "Total memory used by CFG data", SCALE (total), 2361 LABEL (total)); 2362 fprintf (file, "---------------------------------------------------------\n"); 2363 fprintf (file, "\n"); 2364 2365 if (cfg_stats.num_merged_labels > max_num_merged_labels) 2366 max_num_merged_labels = cfg_stats.num_merged_labels; 2367 2368 fprintf (file, "Coalesced label blocks: %ld (Max so far: %ld)\n", 2369 cfg_stats.num_merged_labels, max_num_merged_labels); 2370 2371 fprintf (file, "\n"); 2372} 2373 2374 2375/* Dump CFG statistics on stderr. Keep extern so that it's always 2376 linked in the final executable. */ 2377 2378void 2379debug_cfg_stats (void) 2380{ 2381 dump_cfg_stats (stderr); 2382} 2383 2384 2385/* Dump the flowgraph to a .vcg FILE. */ 2386 2387static void 2388tree_cfg2vcg (FILE *file) 2389{ 2390 edge e; 2391 edge_iterator ei; 2392 basic_block bb; 2393 const char *funcname 2394 = lang_hooks.decl_printable_name (current_function_decl, 2); 2395 2396 /* Write the file header. */ 2397 fprintf (file, "graph: { title: \"%s\"\n", funcname); 2398 fprintf (file, "node: { title: \"ENTRY\" label: \"ENTRY\" }\n"); 2399 fprintf (file, "node: { title: \"EXIT\" label: \"EXIT\" }\n"); 2400 2401 /* Write blocks and edges. */ 2402 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs) 2403 { 2404 fprintf (file, "edge: { sourcename: \"ENTRY\" targetname: \"%d\"", 2405 e->dest->index); 2406 2407 if (e->flags & EDGE_FAKE) 2408 fprintf (file, " linestyle: dotted priority: 10"); 2409 else 2410 fprintf (file, " linestyle: solid priority: 100"); 2411 2412 fprintf (file, " }\n"); 2413 } 2414 fputc ('\n', file); 2415 2416 FOR_EACH_BB (bb) 2417 { 2418 enum tree_code head_code, end_code; 2419 const char *head_name, *end_name; 2420 int head_line = 0; 2421 int end_line = 0; 2422 tree first = first_stmt (bb); 2423 tree last = last_stmt (bb); 2424 2425 if (first) 2426 { 2427 head_code = TREE_CODE (first); 2428 head_name = tree_code_name[head_code]; 2429 head_line = get_lineno (first); 2430 } 2431 else 2432 head_name = "no-statement"; 2433 2434 if (last) 2435 { 2436 end_code = TREE_CODE (last); 2437 end_name = tree_code_name[end_code]; 2438 end_line = get_lineno (last); 2439 } 2440 else 2441 end_name = "no-statement"; 2442 2443 fprintf (file, "node: { title: \"%d\" label: \"#%d\\n%s (%d)\\n%s (%d)\"}\n", 2444 bb->index, bb->index, head_name, head_line, end_name, 2445 end_line); 2446 2447 FOR_EACH_EDGE (e, ei, bb->succs) 2448 { 2449 if (e->dest == EXIT_BLOCK_PTR) 2450 fprintf (file, "edge: { sourcename: \"%d\" targetname: \"EXIT\"", bb->index); 2451 else 2452 fprintf (file, "edge: { sourcename: \"%d\" targetname: \"%d\"", bb->index, e->dest->index); 2453 2454 if (e->flags & EDGE_FAKE) 2455 fprintf (file, " priority: 10 linestyle: dotted"); 2456 else 2457 fprintf (file, " priority: 100 linestyle: solid"); 2458 2459 fprintf (file, " }\n"); 2460 } 2461 2462 if (bb->next_bb != EXIT_BLOCK_PTR) 2463 fputc ('\n', file); 2464 } 2465 2466 fputs ("}\n\n", file); 2467} 2468 2469 2470 2471/*--------------------------------------------------------------------------- 2472 Miscellaneous helpers 2473---------------------------------------------------------------------------*/ 2474 2475/* Return true if T represents a stmt that always transfers control. */ 2476 2477bool 2478is_ctrl_stmt (tree t) 2479{ 2480 return (TREE_CODE (t) == COND_EXPR 2481 || TREE_CODE (t) == SWITCH_EXPR 2482 || TREE_CODE (t) == GOTO_EXPR 2483 || TREE_CODE (t) == RETURN_EXPR 2484 || TREE_CODE (t) == RESX_EXPR); 2485} 2486 2487 2488/* Return true if T is a statement that may alter the flow of control 2489 (e.g., a call to a non-returning function). */ 2490 2491bool 2492is_ctrl_altering_stmt (tree t) 2493{ 2494 tree call; 2495 2496 gcc_assert (t); 2497 call = get_call_expr_in (t); 2498 if (call) 2499 { 2500 /* A non-pure/const CALL_EXPR alters flow control if the current 2501 function has nonlocal labels. */ 2502 if (TREE_SIDE_EFFECTS (call) && current_function_has_nonlocal_label) 2503 return true; 2504 2505 /* A CALL_EXPR also alters control flow if it does not return. */ 2506 if (call_expr_flags (call) & ECF_NORETURN) 2507 return true; 2508 } 2509 2510 /* OpenMP directives alter control flow. */ 2511 if (OMP_DIRECTIVE_P (t)) 2512 return true; 2513 2514 /* If a statement can throw, it alters control flow. */ 2515 return tree_can_throw_internal (t); 2516} 2517 2518 2519/* Return true if T is a computed goto. */ 2520 2521bool 2522computed_goto_p (tree t) 2523{ 2524 return (TREE_CODE (t) == GOTO_EXPR 2525 && TREE_CODE (GOTO_DESTINATION (t)) != LABEL_DECL); 2526} 2527 2528 2529/* Return true if T is a simple local goto. */ 2530 2531bool 2532simple_goto_p (tree t) 2533{ 2534 return (TREE_CODE (t) == GOTO_EXPR 2535 && TREE_CODE (GOTO_DESTINATION (t)) == LABEL_DECL); 2536} 2537 2538 2539/* Return true if T can make an abnormal transfer of control flow. 2540 Transfers of control flow associated with EH are excluded. */ 2541 2542bool 2543tree_can_make_abnormal_goto (tree t) 2544{ 2545 if (computed_goto_p (t)) 2546 return true; 2547 if (TREE_CODE (t) == MODIFY_EXPR) 2548 t = TREE_OPERAND (t, 1); 2549 if (TREE_CODE (t) == WITH_SIZE_EXPR) 2550 t = TREE_OPERAND (t, 0); 2551 if (TREE_CODE (t) == CALL_EXPR) 2552 return TREE_SIDE_EFFECTS (t) && current_function_has_nonlocal_label; 2553 return false; 2554} 2555 2556 2557/* Return true if T should start a new basic block. PREV_T is the 2558 statement preceding T. It is used when T is a label or a case label. 2559 Labels should only start a new basic block if their previous statement 2560 wasn't a label. Otherwise, sequence of labels would generate 2561 unnecessary basic blocks that only contain a single label. */ 2562 2563static inline bool 2564stmt_starts_bb_p (tree t, tree prev_t) 2565{ 2566 if (t == NULL_TREE) 2567 return false; 2568 2569 /* LABEL_EXPRs start a new basic block only if the preceding 2570 statement wasn't a label of the same type. This prevents the 2571 creation of consecutive blocks that have nothing but a single 2572 label. */ 2573 if (TREE_CODE (t) == LABEL_EXPR) 2574 { 2575 /* Nonlocal and computed GOTO targets always start a new block. */ 2576 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (t)) 2577 || FORCED_LABEL (LABEL_EXPR_LABEL (t))) 2578 return true; 2579 2580 if (prev_t && TREE_CODE (prev_t) == LABEL_EXPR) 2581 { 2582 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (prev_t))) 2583 return true; 2584 2585 cfg_stats.num_merged_labels++; 2586 return false; 2587 } 2588 else 2589 return true; 2590 } 2591 2592 return false; 2593} 2594 2595 2596/* Return true if T should end a basic block. */ 2597 2598bool 2599stmt_ends_bb_p (tree t) 2600{ 2601 return is_ctrl_stmt (t) || is_ctrl_altering_stmt (t); 2602} 2603 2604 2605/* Add gotos that used to be represented implicitly in the CFG. */ 2606 2607void 2608disband_implicit_edges (void) 2609{ 2610 basic_block bb; 2611 block_stmt_iterator last; 2612 edge e; 2613 edge_iterator ei; 2614 tree stmt, label; 2615 2616 FOR_EACH_BB (bb) 2617 { 2618 last = bsi_last (bb); 2619 stmt = last_stmt (bb); 2620 2621 if (stmt && TREE_CODE (stmt) == COND_EXPR) 2622 { 2623 /* Remove superfluous gotos from COND_EXPR branches. Moved 2624 from cfg_remove_useless_stmts here since it violates the 2625 invariants for tree--cfg correspondence and thus fits better 2626 here where we do it anyway. */ 2627 e = find_edge (bb, bb->next_bb); 2628 if (e) 2629 { 2630 if (e->flags & EDGE_TRUE_VALUE) 2631 COND_EXPR_THEN (stmt) = build_empty_stmt (); 2632 else if (e->flags & EDGE_FALSE_VALUE) 2633 COND_EXPR_ELSE (stmt) = build_empty_stmt (); 2634 else 2635 gcc_unreachable (); 2636 e->flags |= EDGE_FALLTHRU; 2637 } 2638 2639 continue; 2640 } 2641 2642 if (stmt && TREE_CODE (stmt) == RETURN_EXPR) 2643 { 2644 /* Remove the RETURN_EXPR if we may fall though to the exit 2645 instead. */ 2646 gcc_assert (single_succ_p (bb)); 2647 gcc_assert (single_succ (bb) == EXIT_BLOCK_PTR); 2648 2649 if (bb->next_bb == EXIT_BLOCK_PTR 2650 && !TREE_OPERAND (stmt, 0)) 2651 { 2652 bsi_remove (&last, true); 2653 single_succ_edge (bb)->flags |= EDGE_FALLTHRU; 2654 } 2655 continue; 2656 } 2657 2658 /* There can be no fallthru edge if the last statement is a control 2659 one. */ 2660 if (stmt && is_ctrl_stmt (stmt)) 2661 continue; 2662 2663 /* Find a fallthru edge and emit the goto if necessary. */ 2664 FOR_EACH_EDGE (e, ei, bb->succs) 2665 if (e->flags & EDGE_FALLTHRU) 2666 break; 2667 2668 if (!e || e->dest == bb->next_bb) 2669 continue; 2670 2671 gcc_assert (e->dest != EXIT_BLOCK_PTR); 2672 label = tree_block_label (e->dest); 2673 2674 stmt = build1 (GOTO_EXPR, void_type_node, label); 2675#ifdef USE_MAPPED_LOCATION 2676 SET_EXPR_LOCATION (stmt, e->goto_locus); 2677#else 2678 SET_EXPR_LOCUS (stmt, e->goto_locus); 2679#endif 2680 bsi_insert_after (&last, stmt, BSI_NEW_STMT); 2681 e->flags &= ~EDGE_FALLTHRU; 2682 } 2683} 2684 2685/* Remove block annotations and other datastructures. */ 2686 2687void 2688delete_tree_cfg_annotations (void) 2689{ 2690 label_to_block_map = NULL; 2691} 2692 2693 2694/* Return the first statement in basic block BB. */ 2695 2696tree 2697first_stmt (basic_block bb) 2698{ 2699 block_stmt_iterator i = bsi_start (bb); 2700 return !bsi_end_p (i) ? bsi_stmt (i) : NULL_TREE; 2701} 2702 2703 2704/* Return the last statement in basic block BB. */ 2705 2706tree 2707last_stmt (basic_block bb) 2708{ 2709 block_stmt_iterator b = bsi_last (bb); 2710 return !bsi_end_p (b) ? bsi_stmt (b) : NULL_TREE; 2711} 2712 2713 2714/* Return a pointer to the last statement in block BB. */ 2715 2716tree * 2717last_stmt_ptr (basic_block bb) 2718{ 2719 block_stmt_iterator last = bsi_last (bb); 2720 return !bsi_end_p (last) ? bsi_stmt_ptr (last) : NULL; 2721} 2722 2723 2724/* Return the last statement of an otherwise empty block. Return NULL 2725 if the block is totally empty, or if it contains more than one 2726 statement. */ 2727 2728tree 2729last_and_only_stmt (basic_block bb) 2730{ 2731 block_stmt_iterator i = bsi_last (bb); 2732 tree last, prev; 2733 2734 if (bsi_end_p (i)) 2735 return NULL_TREE; 2736 2737 last = bsi_stmt (i); 2738 bsi_prev (&i); 2739 if (bsi_end_p (i)) 2740 return last; 2741 2742 /* Empty statements should no longer appear in the instruction stream. 2743 Everything that might have appeared before should be deleted by 2744 remove_useless_stmts, and the optimizers should just bsi_remove 2745 instead of smashing with build_empty_stmt. 2746 2747 Thus the only thing that should appear here in a block containing 2748 one executable statement is a label. */ 2749 prev = bsi_stmt (i); 2750 if (TREE_CODE (prev) == LABEL_EXPR) 2751 return last; 2752 else 2753 return NULL_TREE; 2754} 2755 2756 2757/* Mark BB as the basic block holding statement T. */ 2758 2759void 2760set_bb_for_stmt (tree t, basic_block bb) 2761{ 2762 if (TREE_CODE (t) == PHI_NODE) 2763 PHI_BB (t) = bb; 2764 else if (TREE_CODE (t) == STATEMENT_LIST) 2765 { 2766 tree_stmt_iterator i; 2767 for (i = tsi_start (t); !tsi_end_p (i); tsi_next (&i)) 2768 set_bb_for_stmt (tsi_stmt (i), bb); 2769 } 2770 else 2771 { 2772 stmt_ann_t ann = get_stmt_ann (t); 2773 ann->bb = bb; 2774 2775 /* If the statement is a label, add the label to block-to-labels map 2776 so that we can speed up edge creation for GOTO_EXPRs. */ 2777 if (TREE_CODE (t) == LABEL_EXPR) 2778 { 2779 int uid; 2780 2781 t = LABEL_EXPR_LABEL (t); 2782 uid = LABEL_DECL_UID (t); 2783 if (uid == -1) 2784 { 2785 unsigned old_len = VEC_length (basic_block, label_to_block_map); 2786 LABEL_DECL_UID (t) = uid = cfun->last_label_uid++; 2787 if (old_len <= (unsigned) uid) 2788 { 2789 basic_block *addr; 2790 unsigned new_len = 3 * uid / 2; 2791 2792 VEC_safe_grow (basic_block, gc, label_to_block_map, 2793 new_len); 2794 addr = VEC_address (basic_block, label_to_block_map); 2795 memset (&addr[old_len], 2796 0, sizeof (basic_block) * (new_len - old_len)); 2797 } 2798 } 2799 else 2800 /* We're moving an existing label. Make sure that we've 2801 removed it from the old block. */ 2802 gcc_assert (!bb 2803 || !VEC_index (basic_block, label_to_block_map, uid)); 2804 VEC_replace (basic_block, label_to_block_map, uid, bb); 2805 } 2806 } 2807} 2808 2809/* Faster version of set_bb_for_stmt that assume that statement is being moved 2810 from one basic block to another. 2811 For BB splitting we can run into quadratic case, so performance is quite 2812 important and knowing that the tables are big enough, change_bb_for_stmt 2813 can inline as leaf function. */ 2814static inline void 2815change_bb_for_stmt (tree t, basic_block bb) 2816{ 2817 get_stmt_ann (t)->bb = bb; 2818 if (TREE_CODE (t) == LABEL_EXPR) 2819 VEC_replace (basic_block, label_to_block_map, 2820 LABEL_DECL_UID (LABEL_EXPR_LABEL (t)), bb); 2821} 2822 2823/* Finds iterator for STMT. */ 2824 2825extern block_stmt_iterator 2826bsi_for_stmt (tree stmt) 2827{ 2828 block_stmt_iterator bsi; 2829 2830 for (bsi = bsi_start (bb_for_stmt (stmt)); !bsi_end_p (bsi); bsi_next (&bsi)) 2831 if (bsi_stmt (bsi) == stmt) 2832 return bsi; 2833 2834 gcc_unreachable (); 2835} 2836 2837/* Mark statement T as modified, and update it. */ 2838static inline void 2839update_modified_stmts (tree t) 2840{ 2841 if (TREE_CODE (t) == STATEMENT_LIST) 2842 { 2843 tree_stmt_iterator i; 2844 tree stmt; 2845 for (i = tsi_start (t); !tsi_end_p (i); tsi_next (&i)) 2846 { 2847 stmt = tsi_stmt (i); 2848 update_stmt_if_modified (stmt); 2849 } 2850 } 2851 else 2852 update_stmt_if_modified (t); 2853} 2854 2855/* Insert statement (or statement list) T before the statement 2856 pointed-to by iterator I. M specifies how to update iterator I 2857 after insertion (see enum bsi_iterator_update). */ 2858 2859void 2860bsi_insert_before (block_stmt_iterator *i, tree t, enum bsi_iterator_update m) 2861{ 2862 set_bb_for_stmt (t, i->bb); 2863 update_modified_stmts (t); 2864 tsi_link_before (&i->tsi, t, (enum tsi_iterator_update) m); 2865} 2866 2867 2868/* Insert statement (or statement list) T after the statement 2869 pointed-to by iterator I. M specifies how to update iterator I 2870 after insertion (see enum bsi_iterator_update). */ 2871 2872void 2873bsi_insert_after (block_stmt_iterator *i, tree t, enum bsi_iterator_update m) 2874{ 2875 set_bb_for_stmt (t, i->bb); 2876 update_modified_stmts (t); 2877 tsi_link_after (&i->tsi, t, (enum tsi_iterator_update) m); 2878} 2879 2880 2881/* Remove the statement pointed to by iterator I. The iterator is updated 2882 to the next statement. 2883 2884 When REMOVE_EH_INFO is true we remove the statement pointed to by 2885 iterator I from the EH tables. Otherwise we do not modify the EH 2886 tables. 2887 2888 Generally, REMOVE_EH_INFO should be true when the statement is going to 2889 be removed from the IL and not reinserted elsewhere. */ 2890 2891void 2892bsi_remove (block_stmt_iterator *i, bool remove_eh_info) 2893{ 2894 tree t = bsi_stmt (*i); 2895 set_bb_for_stmt (t, NULL); 2896 delink_stmt_imm_use (t); 2897 tsi_delink (&i->tsi); 2898 mark_stmt_modified (t); 2899 if (remove_eh_info) 2900 remove_stmt_from_eh_region (t); 2901} 2902 2903 2904/* Move the statement at FROM so it comes right after the statement at TO. */ 2905 2906void 2907bsi_move_after (block_stmt_iterator *from, block_stmt_iterator *to) 2908{ 2909 tree stmt = bsi_stmt (*from); 2910 bsi_remove (from, false); 2911 bsi_insert_after (to, stmt, BSI_SAME_STMT); 2912} 2913 2914 2915/* Move the statement at FROM so it comes right before the statement at TO. */ 2916 2917void 2918bsi_move_before (block_stmt_iterator *from, block_stmt_iterator *to) 2919{ 2920 tree stmt = bsi_stmt (*from); 2921 bsi_remove (from, false); 2922 bsi_insert_before (to, stmt, BSI_SAME_STMT); 2923} 2924 2925 2926/* Move the statement at FROM to the end of basic block BB. */ 2927 2928void 2929bsi_move_to_bb_end (block_stmt_iterator *from, basic_block bb) 2930{ 2931 block_stmt_iterator last = bsi_last (bb); 2932 2933 /* Have to check bsi_end_p because it could be an empty block. */ 2934 if (!bsi_end_p (last) && is_ctrl_stmt (bsi_stmt (last))) 2935 bsi_move_before (from, &last); 2936 else 2937 bsi_move_after (from, &last); 2938} 2939 2940 2941/* Replace the contents of the statement pointed to by iterator BSI 2942 with STMT. If UPDATE_EH_INFO is true, the exception handling 2943 information of the original statement is moved to the new statement. */ 2944 2945void 2946bsi_replace (const block_stmt_iterator *bsi, tree stmt, bool update_eh_info) 2947{ 2948 int eh_region; 2949 tree orig_stmt = bsi_stmt (*bsi); 2950 2951 SET_EXPR_LOCUS (stmt, EXPR_LOCUS (orig_stmt)); 2952 set_bb_for_stmt (stmt, bsi->bb); 2953 2954 /* Preserve EH region information from the original statement, if 2955 requested by the caller. */ 2956 if (update_eh_info) 2957 { 2958 eh_region = lookup_stmt_eh_region (orig_stmt); 2959 if (eh_region >= 0) 2960 { 2961 remove_stmt_from_eh_region (orig_stmt); 2962 add_stmt_to_eh_region (stmt, eh_region); 2963 } 2964 } 2965 2966 delink_stmt_imm_use (orig_stmt); 2967 *bsi_stmt_ptr (*bsi) = stmt; 2968 mark_stmt_modified (stmt); 2969 update_modified_stmts (stmt); 2970} 2971 2972 2973/* Insert the statement pointed-to by BSI into edge E. Every attempt 2974 is made to place the statement in an existing basic block, but 2975 sometimes that isn't possible. When it isn't possible, the edge is 2976 split and the statement is added to the new block. 2977 2978 In all cases, the returned *BSI points to the correct location. The 2979 return value is true if insertion should be done after the location, 2980 or false if it should be done before the location. If new basic block 2981 has to be created, it is stored in *NEW_BB. */ 2982 2983static bool 2984tree_find_edge_insert_loc (edge e, block_stmt_iterator *bsi, 2985 basic_block *new_bb) 2986{ 2987 basic_block dest, src; 2988 tree tmp; 2989 2990 dest = e->dest; 2991 restart: 2992 2993 /* If the destination has one predecessor which has no PHI nodes, 2994 insert there. Except for the exit block. 2995 2996 The requirement for no PHI nodes could be relaxed. Basically we 2997 would have to examine the PHIs to prove that none of them used 2998 the value set by the statement we want to insert on E. That 2999 hardly seems worth the effort. */ 3000 if (single_pred_p (dest) 3001 && ! phi_nodes (dest) 3002 && dest != EXIT_BLOCK_PTR) 3003 { 3004 *bsi = bsi_start (dest); 3005 if (bsi_end_p (*bsi)) 3006 return true; 3007 3008 /* Make sure we insert after any leading labels. */ 3009 tmp = bsi_stmt (*bsi); 3010 while (TREE_CODE (tmp) == LABEL_EXPR) 3011 { 3012 bsi_next (bsi); 3013 if (bsi_end_p (*bsi)) 3014 break; 3015 tmp = bsi_stmt (*bsi); 3016 } 3017 3018 if (bsi_end_p (*bsi)) 3019 { 3020 *bsi = bsi_last (dest); 3021 return true; 3022 } 3023 else 3024 return false; 3025 } 3026 3027 /* If the source has one successor, the edge is not abnormal and 3028 the last statement does not end a basic block, insert there. 3029 Except for the entry block. */ 3030 src = e->src; 3031 if ((e->flags & EDGE_ABNORMAL) == 0 3032 && single_succ_p (src) 3033 && src != ENTRY_BLOCK_PTR) 3034 { 3035 *bsi = bsi_last (src); 3036 if (bsi_end_p (*bsi)) 3037 return true; 3038 3039 tmp = bsi_stmt (*bsi); 3040 if (!stmt_ends_bb_p (tmp)) 3041 return true; 3042 3043 /* Insert code just before returning the value. We may need to decompose 3044 the return in the case it contains non-trivial operand. */ 3045 if (TREE_CODE (tmp) == RETURN_EXPR) 3046 { 3047 tree op = TREE_OPERAND (tmp, 0); 3048 if (op && !is_gimple_val (op)) 3049 { 3050 gcc_assert (TREE_CODE (op) == MODIFY_EXPR); 3051 bsi_insert_before (bsi, op, BSI_NEW_STMT); 3052 TREE_OPERAND (tmp, 0) = TREE_OPERAND (op, 0); 3053 } 3054 bsi_prev (bsi); 3055 return true; 3056 } 3057 } 3058 3059 /* Otherwise, create a new basic block, and split this edge. */ 3060 dest = split_edge (e); 3061 if (new_bb) 3062 *new_bb = dest; 3063 e = single_pred_edge (dest); 3064 goto restart; 3065} 3066 3067 3068/* This routine will commit all pending edge insertions, creating any new 3069 basic blocks which are necessary. */ 3070 3071void 3072bsi_commit_edge_inserts (void) 3073{ 3074 basic_block bb; 3075 edge e; 3076 edge_iterator ei; 3077 3078 bsi_commit_one_edge_insert (single_succ_edge (ENTRY_BLOCK_PTR), NULL); 3079 3080 FOR_EACH_BB (bb) 3081 FOR_EACH_EDGE (e, ei, bb->succs) 3082 bsi_commit_one_edge_insert (e, NULL); 3083} 3084 3085 3086/* Commit insertions pending at edge E. If a new block is created, set NEW_BB 3087 to this block, otherwise set it to NULL. */ 3088 3089void 3090bsi_commit_one_edge_insert (edge e, basic_block *new_bb) 3091{ 3092 if (new_bb) 3093 *new_bb = NULL; 3094 if (PENDING_STMT (e)) 3095 { 3096 block_stmt_iterator bsi; 3097 tree stmt = PENDING_STMT (e); 3098 3099 PENDING_STMT (e) = NULL_TREE; 3100 3101 if (tree_find_edge_insert_loc (e, &bsi, new_bb)) 3102 bsi_insert_after (&bsi, stmt, BSI_NEW_STMT); 3103 else 3104 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT); 3105 } 3106} 3107 3108 3109/* Add STMT to the pending list of edge E. No actual insertion is 3110 made until a call to bsi_commit_edge_inserts () is made. */ 3111 3112void 3113bsi_insert_on_edge (edge e, tree stmt) 3114{ 3115 append_to_statement_list (stmt, &PENDING_STMT (e)); 3116} 3117 3118/* Similar to bsi_insert_on_edge+bsi_commit_edge_inserts. If a new 3119 block has to be created, it is returned. */ 3120 3121basic_block 3122bsi_insert_on_edge_immediate (edge e, tree stmt) 3123{ 3124 block_stmt_iterator bsi; 3125 basic_block new_bb = NULL; 3126 3127 gcc_assert (!PENDING_STMT (e)); 3128 3129 if (tree_find_edge_insert_loc (e, &bsi, &new_bb)) 3130 bsi_insert_after (&bsi, stmt, BSI_NEW_STMT); 3131 else 3132 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT); 3133 3134 return new_bb; 3135} 3136 3137/*--------------------------------------------------------------------------- 3138 Tree specific functions for CFG manipulation 3139---------------------------------------------------------------------------*/ 3140 3141/* Reinstall those PHI arguments queued in OLD_EDGE to NEW_EDGE. */ 3142 3143static void 3144reinstall_phi_args (edge new_edge, edge old_edge) 3145{ 3146 tree var, phi; 3147 3148 if (!PENDING_STMT (old_edge)) 3149 return; 3150 3151 for (var = PENDING_STMT (old_edge), phi = phi_nodes (new_edge->dest); 3152 var && phi; 3153 var = TREE_CHAIN (var), phi = PHI_CHAIN (phi)) 3154 { 3155 tree result = TREE_PURPOSE (var); 3156 tree arg = TREE_VALUE (var); 3157 3158 gcc_assert (result == PHI_RESULT (phi)); 3159 3160 add_phi_arg (phi, arg, new_edge); 3161 } 3162 3163 PENDING_STMT (old_edge) = NULL; 3164} 3165 3166/* Returns the basic block after which the new basic block created 3167 by splitting edge EDGE_IN should be placed. Tries to keep the new block 3168 near its "logical" location. This is of most help to humans looking 3169 at debugging dumps. */ 3170 3171static basic_block 3172split_edge_bb_loc (edge edge_in) 3173{ 3174 basic_block dest = edge_in->dest; 3175 3176 if (dest->prev_bb && find_edge (dest->prev_bb, dest)) 3177 return edge_in->src; 3178 else 3179 return dest->prev_bb; 3180} 3181 3182/* Split a (typically critical) edge EDGE_IN. Return the new block. 3183 Abort on abnormal edges. */ 3184 3185static basic_block 3186tree_split_edge (edge edge_in) 3187{ 3188 basic_block new_bb, after_bb, dest; 3189 edge new_edge, e; 3190 3191 /* Abnormal edges cannot be split. */ 3192 gcc_assert (!(edge_in->flags & EDGE_ABNORMAL)); 3193 3194 dest = edge_in->dest; 3195 3196 after_bb = split_edge_bb_loc (edge_in); 3197 3198 new_bb = create_empty_bb (after_bb); 3199 new_bb->frequency = EDGE_FREQUENCY (edge_in); 3200 new_bb->count = edge_in->count; 3201 new_edge = make_edge (new_bb, dest, EDGE_FALLTHRU); 3202 new_edge->probability = REG_BR_PROB_BASE; 3203 new_edge->count = edge_in->count; 3204 3205 e = redirect_edge_and_branch (edge_in, new_bb); 3206 gcc_assert (e); 3207 reinstall_phi_args (new_edge, e); 3208 3209 return new_bb; 3210} 3211 3212 3213/* Return true when BB has label LABEL in it. */ 3214 3215static bool 3216has_label_p (basic_block bb, tree label) 3217{ 3218 block_stmt_iterator bsi; 3219 3220 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi)) 3221 { 3222 tree stmt = bsi_stmt (bsi); 3223 3224 if (TREE_CODE (stmt) != LABEL_EXPR) 3225 return false; 3226 if (LABEL_EXPR_LABEL (stmt) == label) 3227 return true; 3228 } 3229 return false; 3230} 3231 3232 3233/* Callback for walk_tree, check that all elements with address taken are 3234 properly noticed as such. The DATA is an int* that is 1 if TP was seen 3235 inside a PHI node. */ 3236 3237static tree 3238verify_expr (tree *tp, int *walk_subtrees, void *data ATTRIBUTE_UNUSED) 3239{ 3240 tree t = *tp, x; 3241 bool in_phi = (data != NULL); 3242 3243 if (TYPE_P (t)) 3244 *walk_subtrees = 0; 3245 3246 /* Check operand N for being valid GIMPLE and give error MSG if not. */ 3247#define CHECK_OP(N, MSG) \ 3248 do { if (!is_gimple_val (TREE_OPERAND (t, N))) \ 3249 { error (MSG); return TREE_OPERAND (t, N); }} while (0) 3250 3251 switch (TREE_CODE (t)) 3252 { 3253 case SSA_NAME: 3254 if (SSA_NAME_IN_FREE_LIST (t)) 3255 { 3256 error ("SSA name in freelist but still referenced"); 3257 return *tp; 3258 } 3259 break; 3260 3261 case ASSERT_EXPR: 3262 x = fold (ASSERT_EXPR_COND (t)); 3263 if (x == boolean_false_node) 3264 { 3265 error ("ASSERT_EXPR with an always-false condition"); 3266 return *tp; 3267 } 3268 break; 3269 3270 case MODIFY_EXPR: 3271 x = TREE_OPERAND (t, 0); 3272 if (TREE_CODE (x) == BIT_FIELD_REF 3273 && is_gimple_reg (TREE_OPERAND (x, 0))) 3274 { 3275 error ("GIMPLE register modified with BIT_FIELD_REF"); 3276 return t; 3277 } 3278 break; 3279 3280 case ADDR_EXPR: 3281 { 3282 bool old_invariant; 3283 bool old_constant; 3284 bool old_side_effects; 3285 bool new_invariant; 3286 bool new_constant; 3287 bool new_side_effects; 3288 3289 /* ??? tree-ssa-alias.c may have overlooked dead PHI nodes, missing 3290 dead PHIs that take the address of something. But if the PHI 3291 result is dead, the fact that it takes the address of anything 3292 is irrelevant. Because we can not tell from here if a PHI result 3293 is dead, we just skip this check for PHIs altogether. This means 3294 we may be missing "valid" checks, but what can you do? 3295 This was PR19217. */ 3296 if (in_phi) 3297 break; 3298 3299 old_invariant = TREE_INVARIANT (t); 3300 old_constant = TREE_CONSTANT (t); 3301 old_side_effects = TREE_SIDE_EFFECTS (t); 3302 3303 recompute_tree_invariant_for_addr_expr (t); 3304 new_invariant = TREE_INVARIANT (t); 3305 new_side_effects = TREE_SIDE_EFFECTS (t); 3306 new_constant = TREE_CONSTANT (t); 3307 3308 if (old_invariant != new_invariant) 3309 { 3310 error ("invariant not recomputed when ADDR_EXPR changed"); 3311 return t; 3312 } 3313 3314 if (old_constant != new_constant) 3315 { 3316 error ("constant not recomputed when ADDR_EXPR changed"); 3317 return t; 3318 } 3319 if (old_side_effects != new_side_effects) 3320 { 3321 error ("side effects not recomputed when ADDR_EXPR changed"); 3322 return t; 3323 } 3324 3325 /* Skip any references (they will be checked when we recurse down the 3326 tree) and ensure that any variable used as a prefix is marked 3327 addressable. */ 3328 for (x = TREE_OPERAND (t, 0); 3329 handled_component_p (x); 3330 x = TREE_OPERAND (x, 0)) 3331 ; 3332 3333 if (TREE_CODE (x) != VAR_DECL && TREE_CODE (x) != PARM_DECL) 3334 return NULL; 3335 if (!TREE_ADDRESSABLE (x)) 3336 { 3337 error ("address taken, but ADDRESSABLE bit not set"); 3338 return x; 3339 } 3340 break; 3341 } 3342 3343 case COND_EXPR: 3344 x = COND_EXPR_COND (t); 3345 if (TREE_CODE (TREE_TYPE (x)) != BOOLEAN_TYPE) 3346 { 3347 error ("non-boolean used in condition"); 3348 return x; 3349 } 3350 if (!is_gimple_condexpr (x)) 3351 { 3352 error ("invalid conditional operand"); 3353 return x; 3354 } 3355 break; 3356 3357 case NOP_EXPR: 3358 case CONVERT_EXPR: 3359 case FIX_TRUNC_EXPR: 3360 case FIX_CEIL_EXPR: 3361 case FIX_FLOOR_EXPR: 3362 case FIX_ROUND_EXPR: 3363 case FLOAT_EXPR: 3364 case NEGATE_EXPR: 3365 case ABS_EXPR: 3366 case BIT_NOT_EXPR: 3367 case NON_LVALUE_EXPR: 3368 case TRUTH_NOT_EXPR: 3369 CHECK_OP (0, "invalid operand to unary operator"); 3370 break; 3371 3372 case REALPART_EXPR: 3373 case IMAGPART_EXPR: 3374 case COMPONENT_REF: 3375 case ARRAY_REF: 3376 case ARRAY_RANGE_REF: 3377 case BIT_FIELD_REF: 3378 case VIEW_CONVERT_EXPR: 3379 /* We have a nest of references. Verify that each of the operands 3380 that determine where to reference is either a constant or a variable, 3381 verify that the base is valid, and then show we've already checked 3382 the subtrees. */ 3383 while (handled_component_p (t)) 3384 { 3385 if (TREE_CODE (t) == COMPONENT_REF && TREE_OPERAND (t, 2)) 3386 CHECK_OP (2, "invalid COMPONENT_REF offset operator"); 3387 else if (TREE_CODE (t) == ARRAY_REF 3388 || TREE_CODE (t) == ARRAY_RANGE_REF) 3389 { 3390 CHECK_OP (1, "invalid array index"); 3391 if (TREE_OPERAND (t, 2)) 3392 CHECK_OP (2, "invalid array lower bound"); 3393 if (TREE_OPERAND (t, 3)) 3394 CHECK_OP (3, "invalid array stride"); 3395 } 3396 else if (TREE_CODE (t) == BIT_FIELD_REF) 3397 { 3398 CHECK_OP (1, "invalid operand to BIT_FIELD_REF"); 3399 CHECK_OP (2, "invalid operand to BIT_FIELD_REF"); 3400 } 3401 3402 t = TREE_OPERAND (t, 0); 3403 } 3404 3405 if (!CONSTANT_CLASS_P (t) && !is_gimple_lvalue (t)) 3406 { 3407 error ("invalid reference prefix"); 3408 return t; 3409 } 3410 *walk_subtrees = 0; 3411 break; 3412 3413 case LT_EXPR: 3414 case LE_EXPR: 3415 case GT_EXPR: 3416 case GE_EXPR: 3417 case EQ_EXPR: 3418 case NE_EXPR: 3419 case UNORDERED_EXPR: 3420 case ORDERED_EXPR: 3421 case UNLT_EXPR: 3422 case UNLE_EXPR: 3423 case UNGT_EXPR: 3424 case UNGE_EXPR: 3425 case UNEQ_EXPR: 3426 case LTGT_EXPR: 3427 case PLUS_EXPR: 3428 case MINUS_EXPR: 3429 case MULT_EXPR: 3430 case TRUNC_DIV_EXPR: 3431 case CEIL_DIV_EXPR: 3432 case FLOOR_DIV_EXPR: 3433 case ROUND_DIV_EXPR: 3434 case TRUNC_MOD_EXPR: 3435 case CEIL_MOD_EXPR: 3436 case FLOOR_MOD_EXPR: 3437 case ROUND_MOD_EXPR: 3438 case RDIV_EXPR: 3439 case EXACT_DIV_EXPR: 3440 case MIN_EXPR: 3441 case MAX_EXPR: 3442 case LSHIFT_EXPR: 3443 case RSHIFT_EXPR: 3444 case LROTATE_EXPR: 3445 case RROTATE_EXPR: 3446 case BIT_IOR_EXPR: 3447 case BIT_XOR_EXPR: 3448 case BIT_AND_EXPR: 3449 CHECK_OP (0, "invalid operand to binary operator"); 3450 CHECK_OP (1, "invalid operand to binary operator"); 3451 break; 3452 3453 case CONSTRUCTOR: 3454 if (TREE_CONSTANT (t) && TREE_CODE (TREE_TYPE (t)) == VECTOR_TYPE) 3455 *walk_subtrees = 0; 3456 break; 3457 3458 default: 3459 break; 3460 } 3461 return NULL; 3462 3463#undef CHECK_OP 3464} 3465 3466 3467/* Verify STMT, return true if STMT is not in GIMPLE form. 3468 TODO: Implement type checking. */ 3469 3470static bool 3471verify_stmt (tree stmt, bool last_in_block) 3472{ 3473 tree addr; 3474 3475 if (OMP_DIRECTIVE_P (stmt)) 3476 { 3477 /* OpenMP directives are validated by the FE and never operated 3478 on by the optimizers. Furthermore, OMP_FOR may contain 3479 non-gimple expressions when the main index variable has had 3480 its address taken. This does not affect the loop itself 3481 because the header of an OMP_FOR is merely used to determine 3482 how to setup the parallel iteration. */ 3483 return false; 3484 } 3485 3486 if (!is_gimple_stmt (stmt)) 3487 { 3488 error ("is not a valid GIMPLE statement"); 3489 goto fail; 3490 } 3491 3492 addr = walk_tree (&stmt, verify_expr, NULL, NULL); 3493 if (addr) 3494 { 3495 debug_generic_stmt (addr); 3496 return true; 3497 } 3498 3499 /* If the statement is marked as part of an EH region, then it is 3500 expected that the statement could throw. Verify that when we 3501 have optimizations that simplify statements such that we prove 3502 that they cannot throw, that we update other data structures 3503 to match. */ 3504 if (lookup_stmt_eh_region (stmt) >= 0) 3505 { 3506 if (!tree_could_throw_p (stmt)) 3507 { 3508 error ("statement marked for throw, but doesn%'t"); 3509 goto fail; 3510 } 3511 if (!last_in_block && tree_can_throw_internal (stmt)) 3512 { 3513 error ("statement marked for throw in middle of block"); 3514 goto fail; 3515 } 3516 } 3517 3518 return false; 3519 3520 fail: 3521 debug_generic_stmt (stmt); 3522 return true; 3523} 3524 3525 3526/* Return true when the T can be shared. */ 3527 3528static bool 3529tree_node_can_be_shared (tree t) 3530{ 3531 if (IS_TYPE_OR_DECL_P (t) 3532 || is_gimple_min_invariant (t) 3533 || TREE_CODE (t) == SSA_NAME 3534 || t == error_mark_node 3535 || TREE_CODE (t) == IDENTIFIER_NODE) 3536 return true; 3537 3538 if (TREE_CODE (t) == CASE_LABEL_EXPR) 3539 return true; 3540 3541 while (((TREE_CODE (t) == ARRAY_REF || TREE_CODE (t) == ARRAY_RANGE_REF) 3542 && is_gimple_min_invariant (TREE_OPERAND (t, 1))) 3543 || TREE_CODE (t) == COMPONENT_REF 3544 || TREE_CODE (t) == REALPART_EXPR 3545 || TREE_CODE (t) == IMAGPART_EXPR) 3546 t = TREE_OPERAND (t, 0); 3547 3548 if (DECL_P (t)) 3549 return true; 3550 3551 return false; 3552} 3553 3554 3555/* Called via walk_trees. Verify tree sharing. */ 3556 3557static tree 3558verify_node_sharing (tree * tp, int *walk_subtrees, void *data) 3559{ 3560 htab_t htab = (htab_t) data; 3561 void **slot; 3562 3563 if (tree_node_can_be_shared (*tp)) 3564 { 3565 *walk_subtrees = false; 3566 return NULL; 3567 } 3568 3569 slot = htab_find_slot (htab, *tp, INSERT); 3570 if (*slot) 3571 return (tree) *slot; 3572 *slot = *tp; 3573 3574 return NULL; 3575} 3576 3577 3578/* Verify the GIMPLE statement chain. */ 3579 3580void 3581verify_stmts (void) 3582{ 3583 basic_block bb; 3584 block_stmt_iterator bsi; 3585 bool err = false; 3586 htab_t htab; 3587 tree addr; 3588 3589 timevar_push (TV_TREE_STMT_VERIFY); 3590 htab = htab_create (37, htab_hash_pointer, htab_eq_pointer, NULL); 3591 3592 FOR_EACH_BB (bb) 3593 { 3594 tree phi; 3595 int i; 3596 3597 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi)) 3598 { 3599 int phi_num_args = PHI_NUM_ARGS (phi); 3600 3601 if (bb_for_stmt (phi) != bb) 3602 { 3603 error ("bb_for_stmt (phi) is set to a wrong basic block"); 3604 err |= true; 3605 } 3606 3607 for (i = 0; i < phi_num_args; i++) 3608 { 3609 tree t = PHI_ARG_DEF (phi, i); 3610 tree addr; 3611 3612 /* Addressable variables do have SSA_NAMEs but they 3613 are not considered gimple values. */ 3614 if (TREE_CODE (t) != SSA_NAME 3615 && TREE_CODE (t) != FUNCTION_DECL 3616 && !is_gimple_val (t)) 3617 { 3618 error ("PHI def is not a GIMPLE value"); 3619 debug_generic_stmt (phi); 3620 debug_generic_stmt (t); 3621 err |= true; 3622 } 3623 3624 addr = walk_tree (&t, verify_expr, (void *) 1, NULL); 3625 if (addr) 3626 { 3627 debug_generic_stmt (addr); 3628 err |= true; 3629 } 3630 3631 addr = walk_tree (&t, verify_node_sharing, htab, NULL); 3632 if (addr) 3633 { 3634 error ("incorrect sharing of tree nodes"); 3635 debug_generic_stmt (phi); 3636 debug_generic_stmt (addr); 3637 err |= true; 3638 } 3639 } 3640 } 3641 3642 for (bsi = bsi_start (bb); !bsi_end_p (bsi); ) 3643 { 3644 tree stmt = bsi_stmt (bsi); 3645 3646 if (bb_for_stmt (stmt) != bb) 3647 { 3648 error ("bb_for_stmt (stmt) is set to a wrong basic block"); 3649 err |= true; 3650 } 3651 3652 bsi_next (&bsi); 3653 err |= verify_stmt (stmt, bsi_end_p (bsi)); 3654 addr = walk_tree (&stmt, verify_node_sharing, htab, NULL); 3655 if (addr) 3656 { 3657 error ("incorrect sharing of tree nodes"); 3658 debug_generic_stmt (stmt); 3659 debug_generic_stmt (addr); 3660 err |= true; 3661 } 3662 } 3663 } 3664 3665 if (err) 3666 internal_error ("verify_stmts failed"); 3667 3668 htab_delete (htab); 3669 timevar_pop (TV_TREE_STMT_VERIFY); 3670} 3671 3672 3673/* Verifies that the flow information is OK. */ 3674 3675static int 3676tree_verify_flow_info (void) 3677{ 3678 int err = 0; 3679 basic_block bb; 3680 block_stmt_iterator bsi; 3681 tree stmt; 3682 edge e; 3683 edge_iterator ei; 3684 3685 if (ENTRY_BLOCK_PTR->stmt_list) 3686 { 3687 error ("ENTRY_BLOCK has a statement list associated with it"); 3688 err = 1; 3689 } 3690 3691 if (EXIT_BLOCK_PTR->stmt_list) 3692 { 3693 error ("EXIT_BLOCK has a statement list associated with it"); 3694 err = 1; 3695 } 3696 3697 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds) 3698 if (e->flags & EDGE_FALLTHRU) 3699 { 3700 error ("fallthru to exit from bb %d", e->src->index); 3701 err = 1; 3702 } 3703 3704 FOR_EACH_BB (bb) 3705 { 3706 bool found_ctrl_stmt = false; 3707 3708 stmt = NULL_TREE; 3709 3710 /* Skip labels on the start of basic block. */ 3711 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi)) 3712 { 3713 tree prev_stmt = stmt; 3714 3715 stmt = bsi_stmt (bsi); 3716 3717 if (TREE_CODE (stmt) != LABEL_EXPR) 3718 break; 3719 3720 if (prev_stmt && DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt))) 3721 { 3722 error ("nonlocal label "); 3723 print_generic_expr (stderr, LABEL_EXPR_LABEL (stmt), 0); 3724 fprintf (stderr, " is not first in a sequence of labels in bb %d", 3725 bb->index); 3726 err = 1; 3727 } 3728 3729 if (label_to_block (LABEL_EXPR_LABEL (stmt)) != bb) 3730 { 3731 error ("label "); 3732 print_generic_expr (stderr, LABEL_EXPR_LABEL (stmt), 0); 3733 fprintf (stderr, " to block does not match in bb %d", 3734 bb->index); 3735 err = 1; 3736 } 3737 3738 if (decl_function_context (LABEL_EXPR_LABEL (stmt)) 3739 != current_function_decl) 3740 { 3741 error ("label "); 3742 print_generic_expr (stderr, LABEL_EXPR_LABEL (stmt), 0); 3743 fprintf (stderr, " has incorrect context in bb %d", 3744 bb->index); 3745 err = 1; 3746 } 3747 } 3748 3749 /* Verify that body of basic block BB is free of control flow. */ 3750 for (; !bsi_end_p (bsi); bsi_next (&bsi)) 3751 { 3752 tree stmt = bsi_stmt (bsi); 3753 3754 if (found_ctrl_stmt) 3755 { 3756 error ("control flow in the middle of basic block %d", 3757 bb->index); 3758 err = 1; 3759 } 3760 3761 if (stmt_ends_bb_p (stmt)) 3762 found_ctrl_stmt = true; 3763 3764 if (TREE_CODE (stmt) == LABEL_EXPR) 3765 { 3766 error ("label "); 3767 print_generic_expr (stderr, LABEL_EXPR_LABEL (stmt), 0); 3768 fprintf (stderr, " in the middle of basic block %d", bb->index); 3769 err = 1; 3770 } 3771 } 3772 3773 bsi = bsi_last (bb); 3774 if (bsi_end_p (bsi)) 3775 continue; 3776 3777 stmt = bsi_stmt (bsi); 3778 3779 err |= verify_eh_edges (stmt); 3780 3781 if (is_ctrl_stmt (stmt)) 3782 { 3783 FOR_EACH_EDGE (e, ei, bb->succs) 3784 if (e->flags & EDGE_FALLTHRU) 3785 { 3786 error ("fallthru edge after a control statement in bb %d", 3787 bb->index); 3788 err = 1; 3789 } 3790 } 3791 3792 if (TREE_CODE (stmt) != COND_EXPR) 3793 { 3794 /* Verify that there are no edges with EDGE_TRUE/FALSE_FLAG set 3795 after anything else but if statement. */ 3796 FOR_EACH_EDGE (e, ei, bb->succs) 3797 if (e->flags & (EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)) 3798 { 3799 error ("true/false edge after a non-COND_EXPR in bb %d", 3800 bb->index); 3801 err = 1; 3802 } 3803 } 3804 3805 switch (TREE_CODE (stmt)) 3806 { 3807 case COND_EXPR: 3808 { 3809 edge true_edge; 3810 edge false_edge; 3811 if (TREE_CODE (COND_EXPR_THEN (stmt)) != GOTO_EXPR 3812 || TREE_CODE (COND_EXPR_ELSE (stmt)) != GOTO_EXPR) 3813 { 3814 error ("structured COND_EXPR at the end of bb %d", bb->index); 3815 err = 1; 3816 } 3817 3818 extract_true_false_edges_from_block (bb, &true_edge, &false_edge); 3819 3820 if (!true_edge || !false_edge 3821 || !(true_edge->flags & EDGE_TRUE_VALUE) 3822 || !(false_edge->flags & EDGE_FALSE_VALUE) 3823 || (true_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL)) 3824 || (false_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL)) 3825 || EDGE_COUNT (bb->succs) >= 3) 3826 { 3827 error ("wrong outgoing edge flags at end of bb %d", 3828 bb->index); 3829 err = 1; 3830 } 3831 3832 if (!has_label_p (true_edge->dest, 3833 GOTO_DESTINATION (COND_EXPR_THEN (stmt)))) 3834 { 3835 error ("%<then%> label does not match edge at end of bb %d", 3836 bb->index); 3837 err = 1; 3838 } 3839 3840 if (!has_label_p (false_edge->dest, 3841 GOTO_DESTINATION (COND_EXPR_ELSE (stmt)))) 3842 { 3843 error ("%<else%> label does not match edge at end of bb %d", 3844 bb->index); 3845 err = 1; 3846 } 3847 } 3848 break; 3849 3850 case GOTO_EXPR: 3851 if (simple_goto_p (stmt)) 3852 { 3853 error ("explicit goto at end of bb %d", bb->index); 3854 err = 1; 3855 } 3856 else 3857 { 3858 /* FIXME. We should double check that the labels in the 3859 destination blocks have their address taken. */ 3860 FOR_EACH_EDGE (e, ei, bb->succs) 3861 if ((e->flags & (EDGE_FALLTHRU | EDGE_TRUE_VALUE 3862 | EDGE_FALSE_VALUE)) 3863 || !(e->flags & EDGE_ABNORMAL)) 3864 { 3865 error ("wrong outgoing edge flags at end of bb %d", 3866 bb->index); 3867 err = 1; 3868 } 3869 } 3870 break; 3871 3872 case RETURN_EXPR: 3873 if (!single_succ_p (bb) 3874 || (single_succ_edge (bb)->flags 3875 & (EDGE_FALLTHRU | EDGE_ABNORMAL 3876 | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE))) 3877 { 3878 error ("wrong outgoing edge flags at end of bb %d", bb->index); 3879 err = 1; 3880 } 3881 if (single_succ (bb) != EXIT_BLOCK_PTR) 3882 { 3883 error ("return edge does not point to exit in bb %d", 3884 bb->index); 3885 err = 1; 3886 } 3887 break; 3888 3889 case SWITCH_EXPR: 3890 { 3891 tree prev; 3892 edge e; 3893 size_t i, n; 3894 tree vec; 3895 3896 vec = SWITCH_LABELS (stmt); 3897 n = TREE_VEC_LENGTH (vec); 3898 3899 /* Mark all the destination basic blocks. */ 3900 for (i = 0; i < n; ++i) 3901 { 3902 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i)); 3903 basic_block label_bb = label_to_block (lab); 3904 3905 gcc_assert (!label_bb->aux || label_bb->aux == (void *)1); 3906 label_bb->aux = (void *)1; 3907 } 3908 3909 /* Verify that the case labels are sorted. */ 3910 prev = TREE_VEC_ELT (vec, 0); 3911 for (i = 1; i < n - 1; ++i) 3912 { 3913 tree c = TREE_VEC_ELT (vec, i); 3914 if (! CASE_LOW (c)) 3915 { 3916 error ("found default case not at end of case vector"); 3917 err = 1; 3918 continue; 3919 } 3920 if (! tree_int_cst_lt (CASE_LOW (prev), CASE_LOW (c))) 3921 { 3922 error ("case labels not sorted: "); 3923 print_generic_expr (stderr, prev, 0); 3924 fprintf (stderr," is greater than "); 3925 print_generic_expr (stderr, c, 0); 3926 fprintf (stderr," but comes before it.\n"); 3927 err = 1; 3928 } 3929 prev = c; 3930 } 3931 if (CASE_LOW (TREE_VEC_ELT (vec, n - 1))) 3932 { 3933 error ("no default case found at end of case vector"); 3934 err = 1; 3935 } 3936 3937 FOR_EACH_EDGE (e, ei, bb->succs) 3938 { 3939 if (!e->dest->aux) 3940 { 3941 error ("extra outgoing edge %d->%d", 3942 bb->index, e->dest->index); 3943 err = 1; 3944 } 3945 e->dest->aux = (void *)2; 3946 if ((e->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL 3947 | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE))) 3948 { 3949 error ("wrong outgoing edge flags at end of bb %d", 3950 bb->index); 3951 err = 1; 3952 } 3953 } 3954 3955 /* Check that we have all of them. */ 3956 for (i = 0; i < n; ++i) 3957 { 3958 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i)); 3959 basic_block label_bb = label_to_block (lab); 3960 3961 if (label_bb->aux != (void *)2) 3962 { 3963 error ("missing edge %i->%i", 3964 bb->index, label_bb->index); 3965 err = 1; 3966 } 3967 } 3968 3969 FOR_EACH_EDGE (e, ei, bb->succs) 3970 e->dest->aux = (void *)0; 3971 } 3972 3973 default: ; 3974 } 3975 } 3976 3977 if (dom_computed[CDI_DOMINATORS] >= DOM_NO_FAST_QUERY) 3978 verify_dominators (CDI_DOMINATORS); 3979 3980 return err; 3981} 3982 3983 3984/* Updates phi nodes after creating a forwarder block joined 3985 by edge FALLTHRU. */ 3986 3987static void 3988tree_make_forwarder_block (edge fallthru) 3989{ 3990 edge e; 3991 edge_iterator ei; 3992 basic_block dummy, bb; 3993 tree phi, new_phi, var; 3994 3995 dummy = fallthru->src; 3996 bb = fallthru->dest; 3997 3998 if (single_pred_p (bb)) 3999 return; 4000 4001 /* If we redirected a branch we must create new phi nodes at the 4002 start of BB. */ 4003 for (phi = phi_nodes (dummy); phi; phi = PHI_CHAIN (phi)) 4004 { 4005 var = PHI_RESULT (phi); 4006 new_phi = create_phi_node (var, bb); 4007 SSA_NAME_DEF_STMT (var) = new_phi; 4008 SET_PHI_RESULT (phi, make_ssa_name (SSA_NAME_VAR (var), phi)); 4009 add_phi_arg (new_phi, PHI_RESULT (phi), fallthru); 4010 } 4011 4012 /* Ensure that the PHI node chain is in the same order. */ 4013 set_phi_nodes (bb, phi_reverse (phi_nodes (bb))); 4014 4015 /* Add the arguments we have stored on edges. */ 4016 FOR_EACH_EDGE (e, ei, bb->preds) 4017 { 4018 if (e == fallthru) 4019 continue; 4020 4021 flush_pending_stmts (e); 4022 } 4023} 4024 4025 4026/* Return a non-special label in the head of basic block BLOCK. 4027 Create one if it doesn't exist. */ 4028 4029tree 4030tree_block_label (basic_block bb) 4031{ 4032 block_stmt_iterator i, s = bsi_start (bb); 4033 bool first = true; 4034 tree label, stmt; 4035 4036 for (i = s; !bsi_end_p (i); first = false, bsi_next (&i)) 4037 { 4038 stmt = bsi_stmt (i); 4039 if (TREE_CODE (stmt) != LABEL_EXPR) 4040 break; 4041 label = LABEL_EXPR_LABEL (stmt); 4042 if (!DECL_NONLOCAL (label)) 4043 { 4044 if (!first) 4045 bsi_move_before (&i, &s); 4046 return label; 4047 } 4048 } 4049 4050 label = create_artificial_label (); 4051 stmt = build1 (LABEL_EXPR, void_type_node, label); 4052 bsi_insert_before (&s, stmt, BSI_NEW_STMT); 4053 return label; 4054} 4055 4056 4057/* Attempt to perform edge redirection by replacing a possibly complex 4058 jump instruction by a goto or by removing the jump completely. 4059 This can apply only if all edges now point to the same block. The 4060 parameters and return values are equivalent to 4061 redirect_edge_and_branch. */ 4062 4063static edge 4064tree_try_redirect_by_replacing_jump (edge e, basic_block target) 4065{ 4066 basic_block src = e->src; 4067 block_stmt_iterator b; 4068 tree stmt; 4069 4070 /* We can replace or remove a complex jump only when we have exactly 4071 two edges. */ 4072 if (EDGE_COUNT (src->succs) != 2 4073 /* Verify that all targets will be TARGET. Specifically, the 4074 edge that is not E must also go to TARGET. */ 4075 || EDGE_SUCC (src, EDGE_SUCC (src, 0) == e)->dest != target) 4076 return NULL; 4077 4078 b = bsi_last (src); 4079 if (bsi_end_p (b)) 4080 return NULL; 4081 stmt = bsi_stmt (b); 4082 4083 if (TREE_CODE (stmt) == COND_EXPR 4084 || TREE_CODE (stmt) == SWITCH_EXPR) 4085 { 4086 bsi_remove (&b, true); 4087 e = ssa_redirect_edge (e, target); 4088 e->flags = EDGE_FALLTHRU; 4089 return e; 4090 } 4091 4092 return NULL; 4093} 4094 4095 4096/* Redirect E to DEST. Return NULL on failure. Otherwise, return the 4097 edge representing the redirected branch. */ 4098 4099static edge 4100tree_redirect_edge_and_branch (edge e, basic_block dest) 4101{ 4102 basic_block bb = e->src; 4103 block_stmt_iterator bsi; 4104 edge ret; 4105 tree label, stmt; 4106 4107 if (e->flags & EDGE_ABNORMAL) 4108 return NULL; 4109 4110 if (e->src != ENTRY_BLOCK_PTR 4111 && (ret = tree_try_redirect_by_replacing_jump (e, dest))) 4112 return ret; 4113 4114 if (e->dest == dest) 4115 return NULL; 4116 4117 label = tree_block_label (dest); 4118 4119 bsi = bsi_last (bb); 4120 stmt = bsi_end_p (bsi) ? NULL : bsi_stmt (bsi); 4121 4122 switch (stmt ? TREE_CODE (stmt) : ERROR_MARK) 4123 { 4124 case COND_EXPR: 4125 stmt = (e->flags & EDGE_TRUE_VALUE 4126 ? COND_EXPR_THEN (stmt) 4127 : COND_EXPR_ELSE (stmt)); 4128 GOTO_DESTINATION (stmt) = label; 4129 break; 4130 4131 case GOTO_EXPR: 4132 /* No non-abnormal edges should lead from a non-simple goto, and 4133 simple ones should be represented implicitly. */ 4134 gcc_unreachable (); 4135 4136 case SWITCH_EXPR: 4137 { 4138 tree cases = get_cases_for_edge (e, stmt); 4139 4140 /* If we have a list of cases associated with E, then use it 4141 as it's a lot faster than walking the entire case vector. */ 4142 if (cases) 4143 { 4144 edge e2 = find_edge (e->src, dest); 4145 tree last, first; 4146 4147 first = cases; 4148 while (cases) 4149 { 4150 last = cases; 4151 CASE_LABEL (cases) = label; 4152 cases = TREE_CHAIN (cases); 4153 } 4154 4155 /* If there was already an edge in the CFG, then we need 4156 to move all the cases associated with E to E2. */ 4157 if (e2) 4158 { 4159 tree cases2 = get_cases_for_edge (e2, stmt); 4160 4161 TREE_CHAIN (last) = TREE_CHAIN (cases2); 4162 TREE_CHAIN (cases2) = first; 4163 } 4164 } 4165 else 4166 { 4167 tree vec = SWITCH_LABELS (stmt); 4168 size_t i, n = TREE_VEC_LENGTH (vec); 4169 4170 for (i = 0; i < n; i++) 4171 { 4172 tree elt = TREE_VEC_ELT (vec, i); 4173 4174 if (label_to_block (CASE_LABEL (elt)) == e->dest) 4175 CASE_LABEL (elt) = label; 4176 } 4177 } 4178 4179 break; 4180 } 4181 4182 case RETURN_EXPR: 4183 bsi_remove (&bsi, true); 4184 e->flags |= EDGE_FALLTHRU; 4185 break; 4186 4187 default: 4188 /* Otherwise it must be a fallthru edge, and we don't need to 4189 do anything besides redirecting it. */ 4190 gcc_assert (e->flags & EDGE_FALLTHRU); 4191 break; 4192 } 4193 4194 /* Update/insert PHI nodes as necessary. */ 4195 4196 /* Now update the edges in the CFG. */ 4197 e = ssa_redirect_edge (e, dest); 4198 4199 return e; 4200} 4201 4202 4203/* Simple wrapper, as we can always redirect fallthru edges. */ 4204 4205static basic_block 4206tree_redirect_edge_and_branch_force (edge e, basic_block dest) 4207{ 4208 e = tree_redirect_edge_and_branch (e, dest); 4209 gcc_assert (e); 4210 4211 return NULL; 4212} 4213 4214 4215/* Splits basic block BB after statement STMT (but at least after the 4216 labels). If STMT is NULL, BB is split just after the labels. */ 4217 4218static basic_block 4219tree_split_block (basic_block bb, void *stmt) 4220{ 4221 block_stmt_iterator bsi; 4222 tree_stmt_iterator tsi_tgt; 4223 tree act; 4224 basic_block new_bb; 4225 edge e; 4226 edge_iterator ei; 4227 4228 new_bb = create_empty_bb (bb); 4229 4230 /* Redirect the outgoing edges. */ 4231 new_bb->succs = bb->succs; 4232 bb->succs = NULL; 4233 FOR_EACH_EDGE (e, ei, new_bb->succs) 4234 e->src = new_bb; 4235 4236 if (stmt && TREE_CODE ((tree) stmt) == LABEL_EXPR) 4237 stmt = NULL; 4238 4239 /* Move everything from BSI to the new basic block. */ 4240 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi)) 4241 { 4242 act = bsi_stmt (bsi); 4243 if (TREE_CODE (act) == LABEL_EXPR) 4244 continue; 4245 4246 if (!stmt) 4247 break; 4248 4249 if (stmt == act) 4250 { 4251 bsi_next (&bsi); 4252 break; 4253 } 4254 } 4255 4256 if (bsi_end_p (bsi)) 4257 return new_bb; 4258 4259 /* Split the statement list - avoid re-creating new containers as this 4260 brings ugly quadratic memory consumption in the inliner. 4261 (We are still quadratic since we need to update stmt BB pointers, 4262 sadly.) */ 4263 new_bb->stmt_list = tsi_split_statement_list_before (&bsi.tsi); 4264 for (tsi_tgt = tsi_start (new_bb->stmt_list); 4265 !tsi_end_p (tsi_tgt); tsi_next (&tsi_tgt)) 4266 change_bb_for_stmt (tsi_stmt (tsi_tgt), new_bb); 4267 4268 return new_bb; 4269} 4270 4271 4272/* Moves basic block BB after block AFTER. */ 4273 4274static bool 4275tree_move_block_after (basic_block bb, basic_block after) 4276{ 4277 if (bb->prev_bb == after) 4278 return true; 4279 4280 unlink_block (bb); 4281 link_block (bb, after); 4282 4283 return true; 4284} 4285 4286 4287/* Return true if basic_block can be duplicated. */ 4288 4289static bool 4290tree_can_duplicate_bb_p (basic_block bb ATTRIBUTE_UNUSED) 4291{ 4292 return true; 4293} 4294 4295 4296/* Create a duplicate of the basic block BB. NOTE: This does not 4297 preserve SSA form. */ 4298 4299static basic_block 4300tree_duplicate_bb (basic_block bb) 4301{ 4302 basic_block new_bb; 4303 block_stmt_iterator bsi, bsi_tgt; 4304 tree phi; 4305 4306 new_bb = create_empty_bb (EXIT_BLOCK_PTR->prev_bb); 4307 4308 /* Copy the PHI nodes. We ignore PHI node arguments here because 4309 the incoming edges have not been setup yet. */ 4310 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi)) 4311 { 4312 tree copy = create_phi_node (PHI_RESULT (phi), new_bb); 4313 create_new_def_for (PHI_RESULT (copy), copy, PHI_RESULT_PTR (copy)); 4314 } 4315 4316 /* Keep the chain of PHI nodes in the same order so that they can be 4317 updated by ssa_redirect_edge. */ 4318 set_phi_nodes (new_bb, phi_reverse (phi_nodes (new_bb))); 4319 4320 bsi_tgt = bsi_start (new_bb); 4321 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi)) 4322 { 4323 def_operand_p def_p; 4324 ssa_op_iter op_iter; 4325 tree stmt, copy; 4326 int region; 4327 4328 stmt = bsi_stmt (bsi); 4329 if (TREE_CODE (stmt) == LABEL_EXPR) 4330 continue; 4331 4332 /* Create a new copy of STMT and duplicate STMT's virtual 4333 operands. */ 4334 copy = unshare_expr (stmt); 4335 bsi_insert_after (&bsi_tgt, copy, BSI_NEW_STMT); 4336 copy_virtual_operands (copy, stmt); 4337 region = lookup_stmt_eh_region (stmt); 4338 if (region >= 0) 4339 add_stmt_to_eh_region (copy, region); 4340 4341 /* Create new names for all the definitions created by COPY and 4342 add replacement mappings for each new name. */ 4343 FOR_EACH_SSA_DEF_OPERAND (def_p, copy, op_iter, SSA_OP_ALL_DEFS) 4344 create_new_def_for (DEF_FROM_PTR (def_p), copy, def_p); 4345 } 4346 4347 return new_bb; 4348} 4349 4350 4351/* Basic block BB_COPY was created by code duplication. Add phi node 4352 arguments for edges going out of BB_COPY. The blocks that were 4353 duplicated have BB_DUPLICATED set. */ 4354 4355void 4356add_phi_args_after_copy_bb (basic_block bb_copy) 4357{ 4358 basic_block bb, dest; 4359 edge e, e_copy; 4360 edge_iterator ei; 4361 tree phi, phi_copy, phi_next, def; 4362 4363 bb = get_bb_original (bb_copy); 4364 4365 FOR_EACH_EDGE (e_copy, ei, bb_copy->succs) 4366 { 4367 if (!phi_nodes (e_copy->dest)) 4368 continue; 4369 4370 if (e_copy->dest->flags & BB_DUPLICATED) 4371 dest = get_bb_original (e_copy->dest); 4372 else 4373 dest = e_copy->dest; 4374 4375 e = find_edge (bb, dest); 4376 if (!e) 4377 { 4378 /* During loop unrolling the target of the latch edge is copied. 4379 In this case we are not looking for edge to dest, but to 4380 duplicated block whose original was dest. */ 4381 FOR_EACH_EDGE (e, ei, bb->succs) 4382 if ((e->dest->flags & BB_DUPLICATED) 4383 && get_bb_original (e->dest) == dest) 4384 break; 4385 4386 gcc_assert (e != NULL); 4387 } 4388 4389 for (phi = phi_nodes (e->dest), phi_copy = phi_nodes (e_copy->dest); 4390 phi; 4391 phi = phi_next, phi_copy = PHI_CHAIN (phi_copy)) 4392 { 4393 phi_next = PHI_CHAIN (phi); 4394 def = PHI_ARG_DEF_FROM_EDGE (phi, e); 4395 add_phi_arg (phi_copy, def, e_copy); 4396 } 4397 } 4398} 4399 4400/* Blocks in REGION_COPY array of length N_REGION were created by 4401 duplication of basic blocks. Add phi node arguments for edges 4402 going from these blocks. */ 4403 4404void 4405add_phi_args_after_copy (basic_block *region_copy, unsigned n_region) 4406{ 4407 unsigned i; 4408 4409 for (i = 0; i < n_region; i++) 4410 region_copy[i]->flags |= BB_DUPLICATED; 4411 4412 for (i = 0; i < n_region; i++) 4413 add_phi_args_after_copy_bb (region_copy[i]); 4414 4415 for (i = 0; i < n_region; i++) 4416 region_copy[i]->flags &= ~BB_DUPLICATED; 4417} 4418 4419/* Duplicates a REGION (set of N_REGION basic blocks) with just a single 4420 important exit edge EXIT. By important we mean that no SSA name defined 4421 inside region is live over the other exit edges of the region. All entry 4422 edges to the region must go to ENTRY->dest. The edge ENTRY is redirected 4423 to the duplicate of the region. SSA form, dominance and loop information 4424 is updated. The new basic blocks are stored to REGION_COPY in the same 4425 order as they had in REGION, provided that REGION_COPY is not NULL. 4426 The function returns false if it is unable to copy the region, 4427 true otherwise. */ 4428 4429bool 4430tree_duplicate_sese_region (edge entry, edge exit, 4431 basic_block *region, unsigned n_region, 4432 basic_block *region_copy) 4433{ 4434 unsigned i, n_doms; 4435 bool free_region_copy = false, copying_header = false; 4436 struct loop *loop = entry->dest->loop_father; 4437 edge exit_copy; 4438 basic_block *doms; 4439 edge redirected; 4440 int total_freq = 0, entry_freq = 0; 4441 gcov_type total_count = 0, entry_count = 0; 4442 4443 if (!can_copy_bbs_p (region, n_region)) 4444 return false; 4445 4446 /* Some sanity checking. Note that we do not check for all possible 4447 missuses of the functions. I.e. if you ask to copy something weird, 4448 it will work, but the state of structures probably will not be 4449 correct. */ 4450 for (i = 0; i < n_region; i++) 4451 { 4452 /* We do not handle subloops, i.e. all the blocks must belong to the 4453 same loop. */ 4454 if (region[i]->loop_father != loop) 4455 return false; 4456 4457 if (region[i] != entry->dest 4458 && region[i] == loop->header) 4459 return false; 4460 } 4461 4462 loop->copy = loop; 4463 4464 /* In case the function is used for loop header copying (which is the primary 4465 use), ensure that EXIT and its copy will be new latch and entry edges. */ 4466 if (loop->header == entry->dest) 4467 { 4468 copying_header = true; 4469 loop->copy = loop->outer; 4470 4471 if (!dominated_by_p (CDI_DOMINATORS, loop->latch, exit->src)) 4472 return false; 4473 4474 for (i = 0; i < n_region; i++) 4475 if (region[i] != exit->src 4476 && dominated_by_p (CDI_DOMINATORS, region[i], exit->src)) 4477 return false; 4478 } 4479 4480 if (!region_copy) 4481 { 4482 region_copy = XNEWVEC (basic_block, n_region); 4483 free_region_copy = true; 4484 } 4485 4486 gcc_assert (!need_ssa_update_p ()); 4487 4488 /* Record blocks outside the region that are dominated by something 4489 inside. */ 4490 doms = XNEWVEC (basic_block, n_basic_blocks); 4491 initialize_original_copy_tables (); 4492 4493 n_doms = get_dominated_by_region (CDI_DOMINATORS, region, n_region, doms); 4494 4495 if (entry->dest->count) 4496 { 4497 total_count = entry->dest->count; 4498 entry_count = entry->count; 4499 /* Fix up corner cases, to avoid division by zero or creation of negative 4500 frequencies. */ 4501 if (entry_count > total_count) 4502 entry_count = total_count; 4503 } 4504 else 4505 { 4506 total_freq = entry->dest->frequency; 4507 entry_freq = EDGE_FREQUENCY (entry); 4508 /* Fix up corner cases, to avoid division by zero or creation of negative 4509 frequencies. */ 4510 if (total_freq == 0) 4511 total_freq = 1; 4512 else if (entry_freq > total_freq) 4513 entry_freq = total_freq; 4514 } 4515 4516 copy_bbs (region, n_region, region_copy, &exit, 1, &exit_copy, loop, 4517 split_edge_bb_loc (entry)); 4518 if (total_count) 4519 { 4520 scale_bbs_frequencies_gcov_type (region, n_region, 4521 total_count - entry_count, 4522 total_count); 4523 scale_bbs_frequencies_gcov_type (region_copy, n_region, entry_count, 4524 total_count); 4525 } 4526 else 4527 { 4528 scale_bbs_frequencies_int (region, n_region, total_freq - entry_freq, 4529 total_freq); 4530 scale_bbs_frequencies_int (region_copy, n_region, entry_freq, total_freq); 4531 } 4532 4533 if (copying_header) 4534 { 4535 loop->header = exit->dest; 4536 loop->latch = exit->src; 4537 } 4538 4539 /* Redirect the entry and add the phi node arguments. */ 4540 redirected = redirect_edge_and_branch (entry, get_bb_copy (entry->dest)); 4541 gcc_assert (redirected != NULL); 4542 flush_pending_stmts (entry); 4543 4544 /* Concerning updating of dominators: We must recount dominators 4545 for entry block and its copy. Anything that is outside of the 4546 region, but was dominated by something inside needs recounting as 4547 well. */ 4548 set_immediate_dominator (CDI_DOMINATORS, entry->dest, entry->src); 4549 doms[n_doms++] = get_bb_original (entry->dest); 4550 iterate_fix_dominators (CDI_DOMINATORS, doms, n_doms); 4551 free (doms); 4552 4553 /* Add the other PHI node arguments. */ 4554 add_phi_args_after_copy (region_copy, n_region); 4555 4556 /* Update the SSA web. */ 4557 update_ssa (TODO_update_ssa); 4558 4559 if (free_region_copy) 4560 free (region_copy); 4561 4562 free_original_copy_tables (); 4563 return true; 4564} 4565 4566/* 4567DEF_VEC_P(basic_block); 4568DEF_VEC_ALLOC_P(basic_block,heap); 4569*/ 4570 4571/* Add all the blocks dominated by ENTRY to the array BBS_P. Stop 4572 adding blocks when the dominator traversal reaches EXIT. This 4573 function silently assumes that ENTRY strictly dominates EXIT. */ 4574 4575static void 4576gather_blocks_in_sese_region (basic_block entry, basic_block exit, 4577 VEC(basic_block,heap) **bbs_p) 4578{ 4579 basic_block son; 4580 4581 for (son = first_dom_son (CDI_DOMINATORS, entry); 4582 son; 4583 son = next_dom_son (CDI_DOMINATORS, son)) 4584 { 4585 VEC_safe_push (basic_block, heap, *bbs_p, son); 4586 if (son != exit) 4587 gather_blocks_in_sese_region (son, exit, bbs_p); 4588 } 4589} 4590 4591 4592struct move_stmt_d 4593{ 4594 tree block; 4595 tree from_context; 4596 tree to_context; 4597 bitmap vars_to_remove; 4598 htab_t new_label_map; 4599 bool remap_decls_p; 4600}; 4601 4602/* Helper for move_block_to_fn. Set TREE_BLOCK in every expression 4603 contained in *TP and change the DECL_CONTEXT of every local 4604 variable referenced in *TP. */ 4605 4606static tree 4607move_stmt_r (tree *tp, int *walk_subtrees, void *data) 4608{ 4609 struct move_stmt_d *p = (struct move_stmt_d *) data; 4610 tree t = *tp; 4611 4612 if (p->block && IS_EXPR_CODE_CLASS (TREE_CODE_CLASS (TREE_CODE (t)))) 4613 TREE_BLOCK (t) = p->block; 4614 4615 if (OMP_DIRECTIVE_P (t) 4616 && TREE_CODE (t) != OMP_RETURN 4617 && TREE_CODE (t) != OMP_CONTINUE) 4618 { 4619 /* Do not remap variables inside OMP directives. Variables 4620 referenced in clauses and directive header belong to the 4621 parent function and should not be moved into the child 4622 function. */ 4623 bool save_remap_decls_p = p->remap_decls_p; 4624 p->remap_decls_p = false; 4625 *walk_subtrees = 0; 4626 4627 walk_tree (&OMP_BODY (t), move_stmt_r, p, NULL); 4628 4629 p->remap_decls_p = save_remap_decls_p; 4630 } 4631 else if (DECL_P (t) && DECL_CONTEXT (t) == p->from_context) 4632 { 4633 if (TREE_CODE (t) == LABEL_DECL) 4634 { 4635 if (p->new_label_map) 4636 { 4637 struct tree_map in, *out; 4638 in.from = t; 4639 out = htab_find_with_hash (p->new_label_map, &in, DECL_UID (t)); 4640 if (out) 4641 *tp = t = out->to; 4642 } 4643 4644 DECL_CONTEXT (t) = p->to_context; 4645 } 4646 else if (p->remap_decls_p) 4647 { 4648 DECL_CONTEXT (t) = p->to_context; 4649 4650 if (TREE_CODE (t) == VAR_DECL) 4651 { 4652 struct function *f = DECL_STRUCT_FUNCTION (p->to_context); 4653 f->unexpanded_var_list 4654 = tree_cons (0, t, f->unexpanded_var_list); 4655 4656 /* Mark T to be removed from the original function, 4657 otherwise it will be given a DECL_RTL when the 4658 original function is expanded. */ 4659 bitmap_set_bit (p->vars_to_remove, DECL_UID (t)); 4660 } 4661 } 4662 } 4663 else if (TYPE_P (t)) 4664 *walk_subtrees = 0; 4665 4666 return NULL_TREE; 4667} 4668 4669 4670/* Move basic block BB from function CFUN to function DEST_FN. The 4671 block is moved out of the original linked list and placed after 4672 block AFTER in the new list. Also, the block is removed from the 4673 original array of blocks and placed in DEST_FN's array of blocks. 4674 If UPDATE_EDGE_COUNT_P is true, the edge counts on both CFGs is 4675 updated to reflect the moved edges. 4676 4677 On exit, local variables that need to be removed from 4678 CFUN->UNEXPANDED_VAR_LIST will have been added to VARS_TO_REMOVE. */ 4679 4680static void 4681move_block_to_fn (struct function *dest_cfun, basic_block bb, 4682 basic_block after, bool update_edge_count_p, 4683 bitmap vars_to_remove, htab_t new_label_map, int eh_offset) 4684{ 4685 struct control_flow_graph *cfg; 4686 edge_iterator ei; 4687 edge e; 4688 block_stmt_iterator si; 4689 struct move_stmt_d d; 4690 unsigned old_len, new_len; 4691 basic_block *addr; 4692 4693 /* Link BB to the new linked list. */ 4694 move_block_after (bb, after); 4695 4696 /* Update the edge count in the corresponding flowgraphs. */ 4697 if (update_edge_count_p) 4698 FOR_EACH_EDGE (e, ei, bb->succs) 4699 { 4700 cfun->cfg->x_n_edges--; 4701 dest_cfun->cfg->x_n_edges++; 4702 } 4703 4704 /* Remove BB from the original basic block array. */ 4705 VEC_replace (basic_block, cfun->cfg->x_basic_block_info, bb->index, NULL); 4706 cfun->cfg->x_n_basic_blocks--; 4707 4708 /* Grow DEST_CFUN's basic block array if needed. */ 4709 cfg = dest_cfun->cfg; 4710 cfg->x_n_basic_blocks++; 4711 if (bb->index > cfg->x_last_basic_block) 4712 cfg->x_last_basic_block = bb->index; 4713 4714 old_len = VEC_length (basic_block, cfg->x_basic_block_info); 4715 if ((unsigned) cfg->x_last_basic_block >= old_len) 4716 { 4717 new_len = cfg->x_last_basic_block + (cfg->x_last_basic_block + 3) / 4; 4718 VEC_safe_grow (basic_block, gc, cfg->x_basic_block_info, new_len); 4719 addr = VEC_address (basic_block, cfg->x_basic_block_info); 4720 memset (&addr[old_len], 0, sizeof (basic_block) * (new_len - old_len)); 4721 } 4722 4723 VEC_replace (basic_block, cfg->x_basic_block_info, 4724 cfg->x_last_basic_block, bb); 4725 4726 /* The statements in BB need to be associated with a new TREE_BLOCK. 4727 Labels need to be associated with a new label-to-block map. */ 4728 memset (&d, 0, sizeof (d)); 4729 d.vars_to_remove = vars_to_remove; 4730 4731 for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si)) 4732 { 4733 tree stmt = bsi_stmt (si); 4734 int region; 4735 4736 d.from_context = cfun->decl; 4737 d.to_context = dest_cfun->decl; 4738 d.remap_decls_p = true; 4739 d.new_label_map = new_label_map; 4740 if (TREE_BLOCK (stmt)) 4741 d.block = DECL_INITIAL (dest_cfun->decl); 4742 4743 walk_tree (&stmt, move_stmt_r, &d, NULL); 4744 4745 if (TREE_CODE (stmt) == LABEL_EXPR) 4746 { 4747 tree label = LABEL_EXPR_LABEL (stmt); 4748 int uid = LABEL_DECL_UID (label); 4749 4750 gcc_assert (uid > -1); 4751 4752 old_len = VEC_length (basic_block, cfg->x_label_to_block_map); 4753 if (old_len <= (unsigned) uid) 4754 { 4755 new_len = 3 * uid / 2; 4756 VEC_safe_grow (basic_block, gc, cfg->x_label_to_block_map, 4757 new_len); 4758 addr = VEC_address (basic_block, cfg->x_label_to_block_map); 4759 memset (&addr[old_len], 0, 4760 sizeof (basic_block) * (new_len - old_len)); 4761 } 4762 4763 VEC_replace (basic_block, cfg->x_label_to_block_map, uid, bb); 4764 VEC_replace (basic_block, cfun->cfg->x_label_to_block_map, uid, NULL); 4765 4766 gcc_assert (DECL_CONTEXT (label) == dest_cfun->decl); 4767 4768 if (uid >= dest_cfun->last_label_uid) 4769 dest_cfun->last_label_uid = uid + 1; 4770 } 4771 else if (TREE_CODE (stmt) == RESX_EXPR && eh_offset != 0) 4772 TREE_OPERAND (stmt, 0) = 4773 build_int_cst (NULL_TREE, 4774 TREE_INT_CST_LOW (TREE_OPERAND (stmt, 0)) 4775 + eh_offset); 4776 4777 region = lookup_stmt_eh_region (stmt); 4778 if (region >= 0) 4779 { 4780 add_stmt_to_eh_region_fn (dest_cfun, stmt, region + eh_offset); 4781 remove_stmt_from_eh_region (stmt); 4782 } 4783 } 4784} 4785 4786/* Examine the statements in BB (which is in SRC_CFUN); find and return 4787 the outermost EH region. Use REGION as the incoming base EH region. */ 4788 4789static int 4790find_outermost_region_in_block (struct function *src_cfun, 4791 basic_block bb, int region) 4792{ 4793 block_stmt_iterator si; 4794 4795 for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si)) 4796 { 4797 tree stmt = bsi_stmt (si); 4798 int stmt_region; 4799 4800 if (TREE_CODE (stmt) == RESX_EXPR) 4801 stmt_region = TREE_INT_CST_LOW (TREE_OPERAND (stmt, 0)); 4802 else 4803 stmt_region = lookup_stmt_eh_region_fn (src_cfun, stmt); 4804 if (stmt_region > 0) 4805 { 4806 if (region < 0) 4807 region = stmt_region; 4808 else if (stmt_region != region) 4809 { 4810 region = eh_region_outermost (src_cfun, stmt_region, region); 4811 gcc_assert (region != -1); 4812 } 4813 } 4814 } 4815 4816 return region; 4817} 4818 4819static tree 4820new_label_mapper (tree decl, void *data) 4821{ 4822 htab_t hash = (htab_t) data; 4823 struct tree_map *m; 4824 void **slot; 4825 4826 gcc_assert (TREE_CODE (decl) == LABEL_DECL); 4827 4828 m = xmalloc (sizeof (struct tree_map)); 4829 m->hash = DECL_UID (decl); 4830 m->from = decl; 4831 m->to = create_artificial_label (); 4832 LABEL_DECL_UID (m->to) = LABEL_DECL_UID (decl); 4833 4834 slot = htab_find_slot_with_hash (hash, m, m->hash, INSERT); 4835 gcc_assert (*slot == NULL); 4836 4837 *slot = m; 4838 4839 return m->to; 4840} 4841 4842/* Move a single-entry, single-exit region delimited by ENTRY_BB and 4843 EXIT_BB to function DEST_CFUN. The whole region is replaced by a 4844 single basic block in the original CFG and the new basic block is 4845 returned. DEST_CFUN must not have a CFG yet. 4846 4847 Note that the region need not be a pure SESE region. Blocks inside 4848 the region may contain calls to abort/exit. The only restriction 4849 is that ENTRY_BB should be the only entry point and it must 4850 dominate EXIT_BB. 4851 4852 All local variables referenced in the region are assumed to be in 4853 the corresponding BLOCK_VARS and unexpanded variable lists 4854 associated with DEST_CFUN. */ 4855 4856basic_block 4857move_sese_region_to_fn (struct function *dest_cfun, basic_block entry_bb, 4858 basic_block exit_bb) 4859{ 4860 VEC(basic_block,heap) *bbs; 4861 basic_block after, bb, *entry_pred, *exit_succ; 4862 struct function *saved_cfun; 4863 int *entry_flag, *exit_flag, eh_offset; 4864 unsigned i, num_entry_edges, num_exit_edges; 4865 edge e; 4866 edge_iterator ei; 4867 bitmap vars_to_remove; 4868 htab_t new_label_map; 4869 4870 saved_cfun = cfun; 4871 4872 /* Collect all the blocks in the region. Manually add ENTRY_BB 4873 because it won't be added by dfs_enumerate_from. */ 4874 calculate_dominance_info (CDI_DOMINATORS); 4875 4876 /* If ENTRY does not strictly dominate EXIT, this cannot be an SESE 4877 region. */ 4878 gcc_assert (entry_bb != exit_bb 4879 && (!exit_bb 4880 || dominated_by_p (CDI_DOMINATORS, exit_bb, entry_bb))); 4881 4882 bbs = NULL; 4883 VEC_safe_push (basic_block, heap, bbs, entry_bb); 4884 gather_blocks_in_sese_region (entry_bb, exit_bb, &bbs); 4885 4886 /* Detach ENTRY_BB and EXIT_BB from CFUN->CFG. We need to remember 4887 the predecessor edges to ENTRY_BB and the successor edges to 4888 EXIT_BB so that we can re-attach them to the new basic block that 4889 will replace the region. */ 4890 num_entry_edges = EDGE_COUNT (entry_bb->preds); 4891 entry_pred = (basic_block *) xcalloc (num_entry_edges, sizeof (basic_block)); 4892 entry_flag = (int *) xcalloc (num_entry_edges, sizeof (int)); 4893 i = 0; 4894 for (ei = ei_start (entry_bb->preds); (e = ei_safe_edge (ei)) != NULL;) 4895 { 4896 entry_flag[i] = e->flags; 4897 entry_pred[i++] = e->src; 4898 remove_edge (e); 4899 } 4900 4901 if (exit_bb) 4902 { 4903 num_exit_edges = EDGE_COUNT (exit_bb->succs); 4904 exit_succ = (basic_block *) xcalloc (num_exit_edges, 4905 sizeof (basic_block)); 4906 exit_flag = (int *) xcalloc (num_exit_edges, sizeof (int)); 4907 i = 0; 4908 for (ei = ei_start (exit_bb->succs); (e = ei_safe_edge (ei)) != NULL;) 4909 { 4910 exit_flag[i] = e->flags; 4911 exit_succ[i++] = e->dest; 4912 remove_edge (e); 4913 } 4914 } 4915 else 4916 { 4917 num_exit_edges = 0; 4918 exit_succ = NULL; 4919 exit_flag = NULL; 4920 } 4921 4922 /* Switch context to the child function to initialize DEST_FN's CFG. */ 4923 gcc_assert (dest_cfun->cfg == NULL); 4924 cfun = dest_cfun; 4925 4926 init_empty_tree_cfg (); 4927 4928 /* Initialize EH information for the new function. */ 4929 eh_offset = 0; 4930 new_label_map = NULL; 4931 if (saved_cfun->eh) 4932 { 4933 int region = -1; 4934 4935 for (i = 0; VEC_iterate (basic_block, bbs, i, bb); i++) 4936 region = find_outermost_region_in_block (saved_cfun, bb, region); 4937 4938 init_eh_for_function (); 4939 if (region != -1) 4940 { 4941 new_label_map = htab_create (17, tree_map_hash, tree_map_eq, free); 4942 eh_offset = duplicate_eh_regions (saved_cfun, new_label_mapper, 4943 new_label_map, region, 0); 4944 } 4945 } 4946 4947 cfun = saved_cfun; 4948 4949 /* Move blocks from BBS into DEST_CFUN. */ 4950 gcc_assert (VEC_length (basic_block, bbs) >= 2); 4951 after = dest_cfun->cfg->x_entry_block_ptr; 4952 vars_to_remove = BITMAP_ALLOC (NULL); 4953 for (i = 0; VEC_iterate (basic_block, bbs, i, bb); i++) 4954 { 4955 /* No need to update edge counts on the last block. It has 4956 already been updated earlier when we detached the region from 4957 the original CFG. */ 4958 move_block_to_fn (dest_cfun, bb, after, bb != exit_bb, vars_to_remove, 4959 new_label_map, eh_offset); 4960 after = bb; 4961 } 4962 4963 if (new_label_map) 4964 htab_delete (new_label_map); 4965 4966 /* Remove the variables marked in VARS_TO_REMOVE from 4967 CFUN->UNEXPANDED_VAR_LIST. Otherwise, they will be given a 4968 DECL_RTL in the context of CFUN. */ 4969 if (!bitmap_empty_p (vars_to_remove)) 4970 { 4971 tree *p; 4972 4973 for (p = &cfun->unexpanded_var_list; *p; ) 4974 { 4975 tree var = TREE_VALUE (*p); 4976 if (bitmap_bit_p (vars_to_remove, DECL_UID (var))) 4977 { 4978 *p = TREE_CHAIN (*p); 4979 continue; 4980 } 4981 4982 p = &TREE_CHAIN (*p); 4983 } 4984 } 4985 4986 BITMAP_FREE (vars_to_remove); 4987 4988 /* Rewire the entry and exit blocks. The successor to the entry 4989 block turns into the successor of DEST_FN's ENTRY_BLOCK_PTR in 4990 the child function. Similarly, the predecessor of DEST_FN's 4991 EXIT_BLOCK_PTR turns into the predecessor of EXIT_BLOCK_PTR. We 4992 need to switch CFUN between DEST_CFUN and SAVED_CFUN so that the 4993 various CFG manipulation function get to the right CFG. 4994 4995 FIXME, this is silly. The CFG ought to become a parameter to 4996 these helpers. */ 4997 cfun = dest_cfun; 4998 make_edge (ENTRY_BLOCK_PTR, entry_bb, EDGE_FALLTHRU); 4999 if (exit_bb) 5000 make_edge (exit_bb, EXIT_BLOCK_PTR, 0); 5001 cfun = saved_cfun; 5002 5003 /* Back in the original function, the SESE region has disappeared, 5004 create a new basic block in its place. */ 5005 bb = create_empty_bb (entry_pred[0]); 5006 for (i = 0; i < num_entry_edges; i++) 5007 make_edge (entry_pred[i], bb, entry_flag[i]); 5008 5009 for (i = 0; i < num_exit_edges; i++) 5010 make_edge (bb, exit_succ[i], exit_flag[i]); 5011 5012 if (exit_bb) 5013 { 5014 free (exit_flag); 5015 free (exit_succ); 5016 } 5017 free (entry_flag); 5018 free (entry_pred); 5019 free_dominance_info (CDI_DOMINATORS); 5020 free_dominance_info (CDI_POST_DOMINATORS); 5021 VEC_free (basic_block, heap, bbs); 5022 5023 return bb; 5024} 5025 5026 5027/* Dump FUNCTION_DECL FN to file FILE using FLAGS (see TDF_* in tree.h) */ 5028 5029void 5030dump_function_to_file (tree fn, FILE *file, int flags) 5031{ 5032 tree arg, vars, var; 5033 bool ignore_topmost_bind = false, any_var = false; 5034 basic_block bb; 5035 tree chain; 5036 struct function *saved_cfun; 5037 5038 fprintf (file, "%s (", lang_hooks.decl_printable_name (fn, 2)); 5039 5040 arg = DECL_ARGUMENTS (fn); 5041 while (arg) 5042 { 5043 print_generic_expr (file, arg, dump_flags); 5044 if (TREE_CHAIN (arg)) 5045 fprintf (file, ", "); 5046 arg = TREE_CHAIN (arg); 5047 } 5048 fprintf (file, ")\n"); 5049 5050 if (flags & TDF_DETAILS) 5051 dump_eh_tree (file, DECL_STRUCT_FUNCTION (fn)); 5052 if (flags & TDF_RAW) 5053 { 5054 dump_node (fn, TDF_SLIM | flags, file); 5055 return; 5056 } 5057 5058 /* Switch CFUN to point to FN. */ 5059 saved_cfun = cfun; 5060 cfun = DECL_STRUCT_FUNCTION (fn); 5061 5062 /* When GIMPLE is lowered, the variables are no longer available in 5063 BIND_EXPRs, so display them separately. */ 5064 if (cfun && cfun->decl == fn && cfun->unexpanded_var_list) 5065 { 5066 ignore_topmost_bind = true; 5067 5068 fprintf (file, "{\n"); 5069 for (vars = cfun->unexpanded_var_list; vars; vars = TREE_CHAIN (vars)) 5070 { 5071 var = TREE_VALUE (vars); 5072 5073 print_generic_decl (file, var, flags); 5074 fprintf (file, "\n"); 5075 5076 any_var = true; 5077 } 5078 } 5079 5080 if (cfun && cfun->decl == fn && cfun->cfg && basic_block_info) 5081 { 5082 /* Make a CFG based dump. */ 5083 check_bb_profile (ENTRY_BLOCK_PTR, file); 5084 if (!ignore_topmost_bind) 5085 fprintf (file, "{\n"); 5086 5087 if (any_var && n_basic_blocks) 5088 fprintf (file, "\n"); 5089 5090 FOR_EACH_BB (bb) 5091 dump_generic_bb (file, bb, 2, flags); 5092 5093 fprintf (file, "}\n"); 5094 check_bb_profile (EXIT_BLOCK_PTR, file); 5095 } 5096 else 5097 { 5098 int indent; 5099 5100 /* Make a tree based dump. */ 5101 chain = DECL_SAVED_TREE (fn); 5102 5103 if (chain && TREE_CODE (chain) == BIND_EXPR) 5104 { 5105 if (ignore_topmost_bind) 5106 { 5107 chain = BIND_EXPR_BODY (chain); 5108 indent = 2; 5109 } 5110 else 5111 indent = 0; 5112 } 5113 else 5114 { 5115 if (!ignore_topmost_bind) 5116 fprintf (file, "{\n"); 5117 indent = 2; 5118 } 5119 5120 if (any_var) 5121 fprintf (file, "\n"); 5122 5123 print_generic_stmt_indented (file, chain, flags, indent); 5124 if (ignore_topmost_bind) 5125 fprintf (file, "}\n"); 5126 } 5127 5128 fprintf (file, "\n\n"); 5129 5130 /* Restore CFUN. */ 5131 cfun = saved_cfun; 5132} 5133 5134 5135/* Dump FUNCTION_DECL FN to stderr using FLAGS (see TDF_* in tree.h) */ 5136 5137void 5138debug_function (tree fn, int flags) 5139{ 5140 dump_function_to_file (fn, stderr, flags); 5141} 5142 5143 5144/* Pretty print of the loops intermediate representation. */ 5145static void print_loop (FILE *, struct loop *, int); 5146static void print_pred_bbs (FILE *, basic_block bb); 5147static void print_succ_bbs (FILE *, basic_block bb); 5148 5149 5150/* Print on FILE the indexes for the predecessors of basic_block BB. */ 5151 5152static void 5153print_pred_bbs (FILE *file, basic_block bb) 5154{ 5155 edge e; 5156 edge_iterator ei; 5157 5158 FOR_EACH_EDGE (e, ei, bb->preds) 5159 fprintf (file, "bb_%d ", e->src->index); 5160} 5161 5162 5163/* Print on FILE the indexes for the successors of basic_block BB. */ 5164 5165static void 5166print_succ_bbs (FILE *file, basic_block bb) 5167{ 5168 edge e; 5169 edge_iterator ei; 5170 5171 FOR_EACH_EDGE (e, ei, bb->succs) 5172 fprintf (file, "bb_%d ", e->dest->index); 5173} 5174 5175 5176/* Pretty print LOOP on FILE, indented INDENT spaces. */ 5177 5178static void 5179print_loop (FILE *file, struct loop *loop, int indent) 5180{ 5181 char *s_indent; 5182 basic_block bb; 5183 5184 if (loop == NULL) 5185 return; 5186 5187 s_indent = (char *) alloca ((size_t) indent + 1); 5188 memset ((void *) s_indent, ' ', (size_t) indent); 5189 s_indent[indent] = '\0'; 5190 5191 /* Print the loop's header. */ 5192 fprintf (file, "%sloop_%d\n", s_indent, loop->num); 5193 5194 /* Print the loop's body. */ 5195 fprintf (file, "%s{\n", s_indent); 5196 FOR_EACH_BB (bb) 5197 if (bb->loop_father == loop) 5198 { 5199 /* Print the basic_block's header. */ 5200 fprintf (file, "%s bb_%d (preds = {", s_indent, bb->index); 5201 print_pred_bbs (file, bb); 5202 fprintf (file, "}, succs = {"); 5203 print_succ_bbs (file, bb); 5204 fprintf (file, "})\n"); 5205 5206 /* Print the basic_block's body. */ 5207 fprintf (file, "%s {\n", s_indent); 5208 tree_dump_bb (bb, file, indent + 4); 5209 fprintf (file, "%s }\n", s_indent); 5210 } 5211 5212 print_loop (file, loop->inner, indent + 2); 5213 fprintf (file, "%s}\n", s_indent); 5214 print_loop (file, loop->next, indent); 5215} 5216 5217 5218/* Follow a CFG edge from the entry point of the program, and on entry 5219 of a loop, pretty print the loop structure on FILE. */ 5220 5221void 5222print_loop_ir (FILE *file) 5223{ 5224 basic_block bb; 5225 5226 bb = BASIC_BLOCK (NUM_FIXED_BLOCKS); 5227 if (bb && bb->loop_father) 5228 print_loop (file, bb->loop_father, 0); 5229} 5230 5231 5232/* Debugging loops structure at tree level. */ 5233 5234void 5235debug_loop_ir (void) 5236{ 5237 print_loop_ir (stderr); 5238} 5239 5240 5241/* Return true if BB ends with a call, possibly followed by some 5242 instructions that must stay with the call. Return false, 5243 otherwise. */ 5244 5245static bool 5246tree_block_ends_with_call_p (basic_block bb) 5247{ 5248 block_stmt_iterator bsi = bsi_last (bb); 5249 return get_call_expr_in (bsi_stmt (bsi)) != NULL; 5250} 5251 5252 5253/* Return true if BB ends with a conditional branch. Return false, 5254 otherwise. */ 5255 5256static bool 5257tree_block_ends_with_condjump_p (basic_block bb) 5258{ 5259 tree stmt = last_stmt (bb); 5260 return (stmt && TREE_CODE (stmt) == COND_EXPR); 5261} 5262 5263 5264/* Return true if we need to add fake edge to exit at statement T. 5265 Helper function for tree_flow_call_edges_add. */ 5266 5267static bool 5268need_fake_edge_p (tree t) 5269{ 5270 tree call; 5271 5272 /* NORETURN and LONGJMP calls already have an edge to exit. 5273 CONST and PURE calls do not need one. 5274 We don't currently check for CONST and PURE here, although 5275 it would be a good idea, because those attributes are 5276 figured out from the RTL in mark_constant_function, and 5277 the counter incrementation code from -fprofile-arcs 5278 leads to different results from -fbranch-probabilities. */ 5279 call = get_call_expr_in (t); 5280 if (call 5281 && !(call_expr_flags (call) & ECF_NORETURN)) 5282 return true; 5283 5284 if (TREE_CODE (t) == ASM_EXPR 5285 && (ASM_VOLATILE_P (t) || ASM_INPUT_P (t))) 5286 return true; 5287 5288 return false; 5289} 5290 5291 5292/* Add fake edges to the function exit for any non constant and non 5293 noreturn calls, volatile inline assembly in the bitmap of blocks 5294 specified by BLOCKS or to the whole CFG if BLOCKS is zero. Return 5295 the number of blocks that were split. 5296 5297 The goal is to expose cases in which entering a basic block does 5298 not imply that all subsequent instructions must be executed. */ 5299 5300static int 5301tree_flow_call_edges_add (sbitmap blocks) 5302{ 5303 int i; 5304 int blocks_split = 0; 5305 int last_bb = last_basic_block; 5306 bool check_last_block = false; 5307 5308 if (n_basic_blocks == NUM_FIXED_BLOCKS) 5309 return 0; 5310 5311 if (! blocks) 5312 check_last_block = true; 5313 else 5314 check_last_block = TEST_BIT (blocks, EXIT_BLOCK_PTR->prev_bb->index); 5315 5316 /* In the last basic block, before epilogue generation, there will be 5317 a fallthru edge to EXIT. Special care is required if the last insn 5318 of the last basic block is a call because make_edge folds duplicate 5319 edges, which would result in the fallthru edge also being marked 5320 fake, which would result in the fallthru edge being removed by 5321 remove_fake_edges, which would result in an invalid CFG. 5322 5323 Moreover, we can't elide the outgoing fake edge, since the block 5324 profiler needs to take this into account in order to solve the minimal 5325 spanning tree in the case that the call doesn't return. 5326 5327 Handle this by adding a dummy instruction in a new last basic block. */ 5328 if (check_last_block) 5329 { 5330 basic_block bb = EXIT_BLOCK_PTR->prev_bb; 5331 block_stmt_iterator bsi = bsi_last (bb); 5332 tree t = NULL_TREE; 5333 if (!bsi_end_p (bsi)) 5334 t = bsi_stmt (bsi); 5335 5336 if (t && need_fake_edge_p (t)) 5337 { 5338 edge e; 5339 5340 e = find_edge (bb, EXIT_BLOCK_PTR); 5341 if (e) 5342 { 5343 bsi_insert_on_edge (e, build_empty_stmt ()); 5344 bsi_commit_edge_inserts (); 5345 } 5346 } 5347 } 5348 5349 /* Now add fake edges to the function exit for any non constant 5350 calls since there is no way that we can determine if they will 5351 return or not... */ 5352 for (i = 0; i < last_bb; i++) 5353 { 5354 basic_block bb = BASIC_BLOCK (i); 5355 block_stmt_iterator bsi; 5356 tree stmt, last_stmt; 5357 5358 if (!bb) 5359 continue; 5360 5361 if (blocks && !TEST_BIT (blocks, i)) 5362 continue; 5363 5364 bsi = bsi_last (bb); 5365 if (!bsi_end_p (bsi)) 5366 { 5367 last_stmt = bsi_stmt (bsi); 5368 do 5369 { 5370 stmt = bsi_stmt (bsi); 5371 if (need_fake_edge_p (stmt)) 5372 { 5373 edge e; 5374 /* The handling above of the final block before the 5375 epilogue should be enough to verify that there is 5376 no edge to the exit block in CFG already. 5377 Calling make_edge in such case would cause us to 5378 mark that edge as fake and remove it later. */ 5379#ifdef ENABLE_CHECKING 5380 if (stmt == last_stmt) 5381 { 5382 e = find_edge (bb, EXIT_BLOCK_PTR); 5383 gcc_assert (e == NULL); 5384 } 5385#endif 5386 5387 /* Note that the following may create a new basic block 5388 and renumber the existing basic blocks. */ 5389 if (stmt != last_stmt) 5390 { 5391 e = split_block (bb, stmt); 5392 if (e) 5393 blocks_split++; 5394 } 5395 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE); 5396 } 5397 bsi_prev (&bsi); 5398 } 5399 while (!bsi_end_p (bsi)); 5400 } 5401 } 5402 5403 if (blocks_split) 5404 verify_flow_info (); 5405 5406 return blocks_split; 5407} 5408 5409/* Purge dead abnormal call edges from basic block BB. */ 5410 5411bool 5412tree_purge_dead_abnormal_call_edges (basic_block bb) 5413{ 5414 bool changed = tree_purge_dead_eh_edges (bb); 5415 5416 if (current_function_has_nonlocal_label) 5417 { 5418 tree stmt = last_stmt (bb); 5419 edge_iterator ei; 5420 edge e; 5421 5422 if (!(stmt && tree_can_make_abnormal_goto (stmt))) 5423 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); ) 5424 { 5425 if (e->flags & EDGE_ABNORMAL) 5426 { 5427 remove_edge (e); 5428 changed = true; 5429 } 5430 else 5431 ei_next (&ei); 5432 } 5433 5434 /* See tree_purge_dead_eh_edges below. */ 5435 if (changed) 5436 free_dominance_info (CDI_DOMINATORS); 5437 } 5438 5439 return changed; 5440} 5441 5442/* Purge dead EH edges from basic block BB. */ 5443 5444bool 5445tree_purge_dead_eh_edges (basic_block bb) 5446{ 5447 bool changed = false; 5448 edge e; 5449 edge_iterator ei; 5450 tree stmt = last_stmt (bb); 5451 5452 if (stmt && tree_can_throw_internal (stmt)) 5453 return false; 5454 5455 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); ) 5456 { 5457 if (e->flags & EDGE_EH) 5458 { 5459 remove_edge (e); 5460 changed = true; 5461 } 5462 else 5463 ei_next (&ei); 5464 } 5465 5466 /* Removal of dead EH edges might change dominators of not 5467 just immediate successors. E.g. when bb1 is changed so that 5468 it no longer can throw and bb1->bb3 and bb1->bb4 are dead 5469 eh edges purged by this function in: 5470 0 5471 / \ 5472 v v 5473 1-->2 5474 / \ | 5475 v v | 5476 3-->4 | 5477 \ v 5478 --->5 5479 | 5480 - 5481 idom(bb5) must be recomputed. For now just free the dominance 5482 info. */ 5483 if (changed) 5484 free_dominance_info (CDI_DOMINATORS); 5485 5486 return changed; 5487} 5488 5489bool 5490tree_purge_all_dead_eh_edges (bitmap blocks) 5491{ 5492 bool changed = false; 5493 unsigned i; 5494 bitmap_iterator bi; 5495 5496 EXECUTE_IF_SET_IN_BITMAP (blocks, 0, i, bi) 5497 { 5498 changed |= tree_purge_dead_eh_edges (BASIC_BLOCK (i)); 5499 } 5500 5501 return changed; 5502} 5503 5504/* This function is called whenever a new edge is created or 5505 redirected. */ 5506 5507static void 5508tree_execute_on_growing_pred (edge e) 5509{ 5510 basic_block bb = e->dest; 5511 5512 if (phi_nodes (bb)) 5513 reserve_phi_args_for_new_edge (bb); 5514} 5515 5516/* This function is called immediately before edge E is removed from 5517 the edge vector E->dest->preds. */ 5518 5519static void 5520tree_execute_on_shrinking_pred (edge e) 5521{ 5522 if (phi_nodes (e->dest)) 5523 remove_phi_args (e); 5524} 5525 5526/*--------------------------------------------------------------------------- 5527 Helper functions for Loop versioning 5528 ---------------------------------------------------------------------------*/ 5529 5530/* Adjust phi nodes for 'first' basic block. 'second' basic block is a copy 5531 of 'first'. Both of them are dominated by 'new_head' basic block. When 5532 'new_head' was created by 'second's incoming edge it received phi arguments 5533 on the edge by split_edge(). Later, additional edge 'e' was created to 5534 connect 'new_head' and 'first'. Now this routine adds phi args on this 5535 additional edge 'e' that new_head to second edge received as part of edge 5536 splitting. 5537*/ 5538 5539static void 5540tree_lv_adjust_loop_header_phi (basic_block first, basic_block second, 5541 basic_block new_head, edge e) 5542{ 5543 tree phi1, phi2; 5544 edge e2 = find_edge (new_head, second); 5545 5546 /* Because NEW_HEAD has been created by splitting SECOND's incoming 5547 edge, we should always have an edge from NEW_HEAD to SECOND. */ 5548 gcc_assert (e2 != NULL); 5549 5550 /* Browse all 'second' basic block phi nodes and add phi args to 5551 edge 'e' for 'first' head. PHI args are always in correct order. */ 5552 5553 for (phi2 = phi_nodes (second), phi1 = phi_nodes (first); 5554 phi2 && phi1; 5555 phi2 = PHI_CHAIN (phi2), phi1 = PHI_CHAIN (phi1)) 5556 { 5557 tree def = PHI_ARG_DEF (phi2, e2->dest_idx); 5558 add_phi_arg (phi1, def, e); 5559 } 5560} 5561 5562/* Adds a if else statement to COND_BB with condition COND_EXPR. 5563 SECOND_HEAD is the destination of the THEN and FIRST_HEAD is 5564 the destination of the ELSE part. */ 5565static void 5566tree_lv_add_condition_to_bb (basic_block first_head, basic_block second_head, 5567 basic_block cond_bb, void *cond_e) 5568{ 5569 block_stmt_iterator bsi; 5570 tree goto1 = NULL_TREE; 5571 tree goto2 = NULL_TREE; 5572 tree new_cond_expr = NULL_TREE; 5573 tree cond_expr = (tree) cond_e; 5574 edge e0; 5575 5576 /* Build new conditional expr */ 5577 goto1 = build1 (GOTO_EXPR, void_type_node, tree_block_label (first_head)); 5578 goto2 = build1 (GOTO_EXPR, void_type_node, tree_block_label (second_head)); 5579 new_cond_expr = build3 (COND_EXPR, void_type_node, cond_expr, goto1, goto2); 5580 5581 /* Add new cond in cond_bb. */ 5582 bsi = bsi_start (cond_bb); 5583 bsi_insert_after (&bsi, new_cond_expr, BSI_NEW_STMT); 5584 /* Adjust edges appropriately to connect new head with first head 5585 as well as second head. */ 5586 e0 = single_succ_edge (cond_bb); 5587 e0->flags &= ~EDGE_FALLTHRU; 5588 e0->flags |= EDGE_FALSE_VALUE; 5589} 5590 5591struct cfg_hooks tree_cfg_hooks = { 5592 "tree", 5593 tree_verify_flow_info, 5594 tree_dump_bb, /* dump_bb */ 5595 create_bb, /* create_basic_block */ 5596 tree_redirect_edge_and_branch,/* redirect_edge_and_branch */ 5597 tree_redirect_edge_and_branch_force,/* redirect_edge_and_branch_force */ 5598 remove_bb, /* delete_basic_block */ 5599 tree_split_block, /* split_block */ 5600 tree_move_block_after, /* move_block_after */ 5601 tree_can_merge_blocks_p, /* can_merge_blocks_p */ 5602 tree_merge_blocks, /* merge_blocks */ 5603 tree_predict_edge, /* predict_edge */ 5604 tree_predicted_by_p, /* predicted_by_p */ 5605 tree_can_duplicate_bb_p, /* can_duplicate_block_p */ 5606 tree_duplicate_bb, /* duplicate_block */ 5607 tree_split_edge, /* split_edge */ 5608 tree_make_forwarder_block, /* make_forward_block */ 5609 NULL, /* tidy_fallthru_edge */ 5610 tree_block_ends_with_call_p, /* block_ends_with_call_p */ 5611 tree_block_ends_with_condjump_p, /* block_ends_with_condjump_p */ 5612 tree_flow_call_edges_add, /* flow_call_edges_add */ 5613 tree_execute_on_growing_pred, /* execute_on_growing_pred */ 5614 tree_execute_on_shrinking_pred, /* execute_on_shrinking_pred */ 5615 tree_duplicate_loop_to_header_edge, /* duplicate loop for trees */ 5616 tree_lv_add_condition_to_bb, /* lv_add_condition_to_bb */ 5617 tree_lv_adjust_loop_header_phi, /* lv_adjust_loop_header_phi*/ 5618 extract_true_false_edges_from_block, /* extract_cond_bb_edges */ 5619 flush_pending_stmts /* flush_pending_stmts */ 5620}; 5621 5622 5623/* Split all critical edges. */ 5624 5625static unsigned int 5626split_critical_edges (void) 5627{ 5628 basic_block bb; 5629 edge e; 5630 edge_iterator ei; 5631 5632 /* split_edge can redirect edges out of SWITCH_EXPRs, which can get 5633 expensive. So we want to enable recording of edge to CASE_LABEL_EXPR 5634 mappings around the calls to split_edge. */ 5635 start_recording_case_labels (); 5636 FOR_ALL_BB (bb) 5637 { 5638 FOR_EACH_EDGE (e, ei, bb->succs) 5639 if (EDGE_CRITICAL_P (e) && !(e->flags & EDGE_ABNORMAL)) 5640 { 5641 split_edge (e); 5642 } 5643 } 5644 end_recording_case_labels (); 5645 return 0; 5646} 5647 5648struct tree_opt_pass pass_split_crit_edges = 5649{ 5650 "crited", /* name */ 5651 NULL, /* gate */ 5652 split_critical_edges, /* execute */ 5653 NULL, /* sub */ 5654 NULL, /* next */ 5655 0, /* static_pass_number */ 5656 TV_TREE_SPLIT_EDGES, /* tv_id */ 5657 PROP_cfg, /* properties required */ 5658 PROP_no_crit_edges, /* properties_provided */ 5659 0, /* properties_destroyed */ 5660 0, /* todo_flags_start */ 5661 TODO_dump_func, /* todo_flags_finish */ 5662 0 /* letter */ 5663}; 5664 5665 5666/* Return EXP if it is a valid GIMPLE rvalue, else gimplify it into 5667 a temporary, make sure and register it to be renamed if necessary, 5668 and finally return the temporary. Put the statements to compute 5669 EXP before the current statement in BSI. */ 5670 5671tree 5672gimplify_val (block_stmt_iterator *bsi, tree type, tree exp) 5673{ 5674 tree t, new_stmt, orig_stmt; 5675 5676 if (is_gimple_val (exp)) 5677 return exp; 5678 5679 t = make_rename_temp (type, NULL); 5680 new_stmt = build2 (MODIFY_EXPR, type, t, exp); 5681 5682 orig_stmt = bsi_stmt (*bsi); 5683 SET_EXPR_LOCUS (new_stmt, EXPR_LOCUS (orig_stmt)); 5684 TREE_BLOCK (new_stmt) = TREE_BLOCK (orig_stmt); 5685 5686 bsi_insert_before (bsi, new_stmt, BSI_SAME_STMT); 5687 if (in_ssa_p) 5688 mark_new_vars_to_rename (new_stmt); 5689 5690 return t; 5691} 5692 5693/* Build a ternary operation and gimplify it. Emit code before BSI. 5694 Return the gimple_val holding the result. */ 5695 5696tree 5697gimplify_build3 (block_stmt_iterator *bsi, enum tree_code code, 5698 tree type, tree a, tree b, tree c) 5699{ 5700 tree ret; 5701 5702 ret = fold_build3 (code, type, a, b, c); 5703 STRIP_NOPS (ret); 5704 5705 return gimplify_val (bsi, type, ret); 5706} 5707 5708/* Build a binary operation and gimplify it. Emit code before BSI. 5709 Return the gimple_val holding the result. */ 5710 5711tree 5712gimplify_build2 (block_stmt_iterator *bsi, enum tree_code code, 5713 tree type, tree a, tree b) 5714{ 5715 tree ret; 5716 5717 ret = fold_build2 (code, type, a, b); 5718 STRIP_NOPS (ret); 5719 5720 return gimplify_val (bsi, type, ret); 5721} 5722 5723/* Build a unary operation and gimplify it. Emit code before BSI. 5724 Return the gimple_val holding the result. */ 5725 5726tree 5727gimplify_build1 (block_stmt_iterator *bsi, enum tree_code code, tree type, 5728 tree a) 5729{ 5730 tree ret; 5731 5732 ret = fold_build1 (code, type, a); 5733 STRIP_NOPS (ret); 5734 5735 return gimplify_val (bsi, type, ret); 5736} 5737 5738 5739 5740/* Emit return warnings. */ 5741 5742static unsigned int 5743execute_warn_function_return (void) 5744{ 5745#ifdef USE_MAPPED_LOCATION 5746 source_location location; 5747#else 5748 location_t *locus; 5749#endif 5750 tree last; 5751 edge e; 5752 edge_iterator ei; 5753 5754 /* If we have a path to EXIT, then we do return. */ 5755 if (TREE_THIS_VOLATILE (cfun->decl) 5756 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) > 0) 5757 { 5758#ifdef USE_MAPPED_LOCATION 5759 location = UNKNOWN_LOCATION; 5760#else 5761 locus = NULL; 5762#endif 5763 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds) 5764 { 5765 last = last_stmt (e->src); 5766 if (TREE_CODE (last) == RETURN_EXPR 5767#ifdef USE_MAPPED_LOCATION 5768 && (location = EXPR_LOCATION (last)) != UNKNOWN_LOCATION) 5769#else 5770 && (locus = EXPR_LOCUS (last)) != NULL) 5771#endif 5772 break; 5773 } 5774#ifdef USE_MAPPED_LOCATION 5775 if (location == UNKNOWN_LOCATION) 5776 location = cfun->function_end_locus; 5777 warning (0, "%H%<noreturn%> function does return", &location); 5778#else 5779 if (!locus) 5780 locus = &cfun->function_end_locus; 5781 warning (0, "%H%<noreturn%> function does return", locus); 5782#endif 5783 } 5784 5785 /* If we see "return;" in some basic block, then we do reach the end 5786 without returning a value. */ 5787 else if (warn_return_type 5788 && !TREE_NO_WARNING (cfun->decl) 5789 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) > 0 5790 && !VOID_TYPE_P (TREE_TYPE (TREE_TYPE (cfun->decl)))) 5791 { 5792 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds) 5793 { 5794 tree last = last_stmt (e->src); 5795 if (TREE_CODE (last) == RETURN_EXPR 5796 && TREE_OPERAND (last, 0) == NULL 5797 && !TREE_NO_WARNING (last)) 5798 { 5799#ifdef USE_MAPPED_LOCATION 5800 location = EXPR_LOCATION (last); 5801 if (location == UNKNOWN_LOCATION) 5802 location = cfun->function_end_locus; 5803 warning (0, "%Hcontrol reaches end of non-void function", &location); 5804#else 5805 locus = EXPR_LOCUS (last); 5806 if (!locus) 5807 locus = &cfun->function_end_locus; 5808 warning (0, "%Hcontrol reaches end of non-void function", locus); 5809#endif 5810 TREE_NO_WARNING (cfun->decl) = 1; 5811 break; 5812 } 5813 } 5814 } 5815 return 0; 5816} 5817 5818 5819/* Given a basic block B which ends with a conditional and has 5820 precisely two successors, determine which of the edges is taken if 5821 the conditional is true and which is taken if the conditional is 5822 false. Set TRUE_EDGE and FALSE_EDGE appropriately. */ 5823 5824void 5825extract_true_false_edges_from_block (basic_block b, 5826 edge *true_edge, 5827 edge *false_edge) 5828{ 5829 edge e = EDGE_SUCC (b, 0); 5830 5831 if (e->flags & EDGE_TRUE_VALUE) 5832 { 5833 *true_edge = e; 5834 *false_edge = EDGE_SUCC (b, 1); 5835 } 5836 else 5837 { 5838 *false_edge = e; 5839 *true_edge = EDGE_SUCC (b, 1); 5840 } 5841} 5842 5843struct tree_opt_pass pass_warn_function_return = 5844{ 5845 NULL, /* name */ 5846 NULL, /* gate */ 5847 execute_warn_function_return, /* execute */ 5848 NULL, /* sub */ 5849 NULL, /* next */ 5850 0, /* static_pass_number */ 5851 0, /* tv_id */ 5852 PROP_cfg, /* properties_required */ 5853 0, /* properties_provided */ 5854 0, /* properties_destroyed */ 5855 0, /* todo_flags_start */ 5856 0, /* todo_flags_finish */ 5857 0 /* letter */ 5858}; 5859 5860/* Emit noreturn warnings. */ 5861 5862static unsigned int 5863execute_warn_function_noreturn (void) 5864{ 5865 if (warn_missing_noreturn 5866 && !TREE_THIS_VOLATILE (cfun->decl) 5867 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) == 0 5868 && !lang_hooks.function.missing_noreturn_ok_p (cfun->decl)) 5869 warning (OPT_Wmissing_noreturn, "%Jfunction might be possible candidate " 5870 "for attribute %<noreturn%>", 5871 cfun->decl); 5872 return 0; 5873} 5874 5875struct tree_opt_pass pass_warn_function_noreturn = 5876{ 5877 NULL, /* name */ 5878 NULL, /* gate */ 5879 execute_warn_function_noreturn, /* execute */ 5880 NULL, /* sub */ 5881 NULL, /* next */ 5882 0, /* static_pass_number */ 5883 0, /* tv_id */ 5884 PROP_cfg, /* properties_required */ 5885 0, /* properties_provided */ 5886 0, /* properties_destroyed */ 5887 0, /* todo_flags_start */ 5888 0, /* todo_flags_finish */ 5889 0 /* letter */ 5890}; 5891