tree-cfg.c revision 225736
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 /* Finally, purge dead labels. All user-defined labels and labels that 1055 can be the target of non-local gotos and labels which have their 1056 address taken are preserved. */ 1057 FOR_EACH_BB (bb) 1058 { 1059 block_stmt_iterator i; 1060 tree label_for_this_bb = label_for_bb[bb->index]; 1061 1062 if (! label_for_this_bb) 1063 continue; 1064 1065 for (i = bsi_start (bb); !bsi_end_p (i); ) 1066 { 1067 tree label, stmt = bsi_stmt (i); 1068 1069 if (TREE_CODE (stmt) != LABEL_EXPR) 1070 break; 1071 1072 label = LABEL_EXPR_LABEL (stmt); 1073 1074 if (label == label_for_this_bb 1075 || ! DECL_ARTIFICIAL (label) 1076 || DECL_NONLOCAL (label) 1077 || FORCED_LABEL (label)) 1078 bsi_next (&i); 1079 else 1080 bsi_remove (&i, true); 1081 } 1082 } 1083 1084 free (label_for_bb); 1085} 1086 1087/* Look for blocks ending in a multiway branch (a SWITCH_EXPR in GIMPLE), 1088 and scan the sorted vector of cases. Combine the ones jumping to the 1089 same label. 1090 Eg. three separate entries 1: 2: 3: become one entry 1..3: */ 1091 1092void 1093group_case_labels (void) 1094{ 1095 basic_block bb; 1096 1097 FOR_EACH_BB (bb) 1098 { 1099 tree stmt = last_stmt (bb); 1100 if (stmt && TREE_CODE (stmt) == SWITCH_EXPR) 1101 { 1102 tree labels = SWITCH_LABELS (stmt); 1103 int old_size = TREE_VEC_LENGTH (labels); 1104 int i, j, new_size = old_size; 1105 tree default_case = TREE_VEC_ELT (labels, old_size - 1); 1106 tree default_label; 1107 1108 /* The default label is always the last case in a switch 1109 statement after gimplification. */ 1110 default_label = CASE_LABEL (default_case); 1111 1112 /* Look for possible opportunities to merge cases. 1113 Ignore the last element of the label vector because it 1114 must be the default case. */ 1115 i = 0; 1116 while (i < old_size - 1) 1117 { 1118 tree base_case, base_label, base_high; 1119 base_case = TREE_VEC_ELT (labels, i); 1120 1121 gcc_assert (base_case); 1122 base_label = CASE_LABEL (base_case); 1123 1124 /* Discard cases that have the same destination as the 1125 default case. */ 1126 if (base_label == default_label) 1127 { 1128 TREE_VEC_ELT (labels, i) = NULL_TREE; 1129 i++; 1130 new_size--; 1131 continue; 1132 } 1133 1134 base_high = CASE_HIGH (base_case) ? 1135 CASE_HIGH (base_case) : CASE_LOW (base_case); 1136 i++; 1137 /* Try to merge case labels. Break out when we reach the end 1138 of the label vector or when we cannot merge the next case 1139 label with the current one. */ 1140 while (i < old_size - 1) 1141 { 1142 tree merge_case = TREE_VEC_ELT (labels, i); 1143 tree merge_label = CASE_LABEL (merge_case); 1144 tree t = int_const_binop (PLUS_EXPR, base_high, 1145 integer_one_node, 1); 1146 1147 /* Merge the cases if they jump to the same place, 1148 and their ranges are consecutive. */ 1149 if (merge_label == base_label 1150 && tree_int_cst_equal (CASE_LOW (merge_case), t)) 1151 { 1152 base_high = CASE_HIGH (merge_case) ? 1153 CASE_HIGH (merge_case) : CASE_LOW (merge_case); 1154 CASE_HIGH (base_case) = base_high; 1155 TREE_VEC_ELT (labels, i) = NULL_TREE; 1156 new_size--; 1157 i++; 1158 } 1159 else 1160 break; 1161 } 1162 } 1163 1164 /* Compress the case labels in the label vector, and adjust the 1165 length of the vector. */ 1166 for (i = 0, j = 0; i < new_size; i++) 1167 { 1168 while (! TREE_VEC_ELT (labels, j)) 1169 j++; 1170 TREE_VEC_ELT (labels, i) = TREE_VEC_ELT (labels, j++); 1171 } 1172 TREE_VEC_LENGTH (labels) = new_size; 1173 } 1174 } 1175} 1176 1177/* Checks whether we can merge block B into block A. */ 1178 1179static bool 1180tree_can_merge_blocks_p (basic_block a, basic_block b) 1181{ 1182 tree stmt; 1183 block_stmt_iterator bsi; 1184 tree phi; 1185 1186 if (!single_succ_p (a)) 1187 return false; 1188 1189 if (single_succ_edge (a)->flags & EDGE_ABNORMAL) 1190 return false; 1191 1192 if (single_succ (a) != b) 1193 return false; 1194 1195 if (!single_pred_p (b)) 1196 return false; 1197 1198 if (b == EXIT_BLOCK_PTR) 1199 return false; 1200 1201 /* If A ends by a statement causing exceptions or something similar, we 1202 cannot merge the blocks. */ 1203 stmt = last_stmt (a); 1204 if (stmt && stmt_ends_bb_p (stmt)) 1205 return false; 1206 1207 /* Do not allow a block with only a non-local label to be merged. */ 1208 if (stmt && TREE_CODE (stmt) == LABEL_EXPR 1209 && DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt))) 1210 return false; 1211 1212 /* It must be possible to eliminate all phi nodes in B. If ssa form 1213 is not up-to-date, we cannot eliminate any phis. */ 1214 phi = phi_nodes (b); 1215 if (phi) 1216 { 1217 if (need_ssa_update_p ()) 1218 return false; 1219 1220 for (; phi; phi = PHI_CHAIN (phi)) 1221 if (!is_gimple_reg (PHI_RESULT (phi)) 1222 && !may_propagate_copy (PHI_RESULT (phi), PHI_ARG_DEF (phi, 0))) 1223 return false; 1224 } 1225 1226 /* Do not remove user labels. */ 1227 for (bsi = bsi_start (b); !bsi_end_p (bsi); bsi_next (&bsi)) 1228 { 1229 stmt = bsi_stmt (bsi); 1230 if (TREE_CODE (stmt) != LABEL_EXPR) 1231 break; 1232 if (!DECL_ARTIFICIAL (LABEL_EXPR_LABEL (stmt))) 1233 return false; 1234 } 1235 1236 /* Protect the loop latches. */ 1237 if (current_loops 1238 && b->loop_father->latch == b) 1239 return false; 1240 1241 return true; 1242} 1243 1244/* Replaces all uses of NAME by VAL. */ 1245 1246void 1247replace_uses_by (tree name, tree val) 1248{ 1249 imm_use_iterator imm_iter; 1250 use_operand_p use; 1251 tree stmt; 1252 edge e; 1253 unsigned i; 1254 1255 1256 FOR_EACH_IMM_USE_STMT (stmt, imm_iter, name) 1257 { 1258 FOR_EACH_IMM_USE_ON_STMT (use, imm_iter) 1259 { 1260 replace_exp (use, val); 1261 1262 if (TREE_CODE (stmt) == PHI_NODE) 1263 { 1264 e = PHI_ARG_EDGE (stmt, PHI_ARG_INDEX_FROM_USE (use)); 1265 if (e->flags & EDGE_ABNORMAL) 1266 { 1267 /* This can only occur for virtual operands, since 1268 for the real ones SSA_NAME_OCCURS_IN_ABNORMAL_PHI (name)) 1269 would prevent replacement. */ 1270 gcc_assert (!is_gimple_reg (name)); 1271 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (val) = 1; 1272 } 1273 } 1274 } 1275 if (TREE_CODE (stmt) != PHI_NODE) 1276 { 1277 tree rhs; 1278 1279 fold_stmt_inplace (stmt); 1280 rhs = get_rhs (stmt); 1281 if (TREE_CODE (rhs) == ADDR_EXPR) 1282 recompute_tree_invariant_for_addr_expr (rhs); 1283 1284 maybe_clean_or_replace_eh_stmt (stmt, stmt); 1285 mark_new_vars_to_rename (stmt); 1286 } 1287 } 1288 1289 gcc_assert (num_imm_uses (name) == 0); 1290 1291 /* Also update the trees stored in loop structures. */ 1292 if (current_loops) 1293 { 1294 struct loop *loop; 1295 1296 for (i = 0; i < current_loops->num; i++) 1297 { 1298 loop = current_loops->parray[i]; 1299 if (loop) 1300 substitute_in_loop_info (loop, name, val); 1301 } 1302 } 1303} 1304 1305/* Merge block B into block A. */ 1306 1307static void 1308tree_merge_blocks (basic_block a, basic_block b) 1309{ 1310 block_stmt_iterator bsi; 1311 tree_stmt_iterator last; 1312 tree phi; 1313 1314 if (dump_file) 1315 fprintf (dump_file, "Merging blocks %d and %d\n", a->index, b->index); 1316 1317 /* Remove all single-valued PHI nodes from block B of the form 1318 V_i = PHI <V_j> by propagating V_j to all the uses of V_i. */ 1319 bsi = bsi_last (a); 1320 for (phi = phi_nodes (b); phi; phi = phi_nodes (b)) 1321 { 1322 tree def = PHI_RESULT (phi), use = PHI_ARG_DEF (phi, 0); 1323 tree copy; 1324 bool may_replace_uses = may_propagate_copy (def, use); 1325 1326 /* In case we have loops to care about, do not propagate arguments of 1327 loop closed ssa phi nodes. */ 1328 if (current_loops 1329 && is_gimple_reg (def) 1330 && TREE_CODE (use) == SSA_NAME 1331 && a->loop_father != b->loop_father) 1332 may_replace_uses = false; 1333 1334 if (!may_replace_uses) 1335 { 1336 gcc_assert (is_gimple_reg (def)); 1337 1338 /* Note that just emitting the copies is fine -- there is no problem 1339 with ordering of phi nodes. This is because A is the single 1340 predecessor of B, therefore results of the phi nodes cannot 1341 appear as arguments of the phi nodes. */ 1342 copy = build2 (MODIFY_EXPR, void_type_node, def, use); 1343 bsi_insert_after (&bsi, copy, BSI_NEW_STMT); 1344 SET_PHI_RESULT (phi, NULL_TREE); 1345 SSA_NAME_DEF_STMT (def) = copy; 1346 } 1347 else 1348 replace_uses_by (def, use); 1349 1350 remove_phi_node (phi, NULL); 1351 } 1352 1353 /* Ensure that B follows A. */ 1354 move_block_after (b, a); 1355 1356 gcc_assert (single_succ_edge (a)->flags & EDGE_FALLTHRU); 1357 gcc_assert (!last_stmt (a) || !stmt_ends_bb_p (last_stmt (a))); 1358 1359 /* Remove labels from B and set bb_for_stmt to A for other statements. */ 1360 for (bsi = bsi_start (b); !bsi_end_p (bsi);) 1361 { 1362 if (TREE_CODE (bsi_stmt (bsi)) == LABEL_EXPR) 1363 { 1364 tree label = bsi_stmt (bsi); 1365 1366 bsi_remove (&bsi, false); 1367 /* Now that we can thread computed gotos, we might have 1368 a situation where we have a forced label in block B 1369 However, the label at the start of block B might still be 1370 used in other ways (think about the runtime checking for 1371 Fortran assigned gotos). So we can not just delete the 1372 label. Instead we move the label to the start of block A. */ 1373 if (FORCED_LABEL (LABEL_EXPR_LABEL (label))) 1374 { 1375 block_stmt_iterator dest_bsi = bsi_start (a); 1376 bsi_insert_before (&dest_bsi, label, BSI_NEW_STMT); 1377 } 1378 } 1379 else 1380 { 1381 change_bb_for_stmt (bsi_stmt (bsi), a); 1382 bsi_next (&bsi); 1383 } 1384 } 1385 1386 /* Merge the chains. */ 1387 last = tsi_last (a->stmt_list); 1388 tsi_link_after (&last, b->stmt_list, TSI_NEW_STMT); 1389 b->stmt_list = NULL; 1390} 1391 1392 1393/* Return the one of two successors of BB that is not reachable by a 1394 reached by a complex edge, if there is one. Else, return BB. We use 1395 this in optimizations that use post-dominators for their heuristics, 1396 to catch the cases in C++ where function calls are involved. */ 1397 1398basic_block 1399single_noncomplex_succ (basic_block bb) 1400{ 1401 edge e0, e1; 1402 if (EDGE_COUNT (bb->succs) != 2) 1403 return bb; 1404 1405 e0 = EDGE_SUCC (bb, 0); 1406 e1 = EDGE_SUCC (bb, 1); 1407 if (e0->flags & EDGE_COMPLEX) 1408 return e1->dest; 1409 if (e1->flags & EDGE_COMPLEX) 1410 return e0->dest; 1411 1412 return bb; 1413} 1414 1415 1416/* Walk the function tree removing unnecessary statements. 1417 1418 * Empty statement nodes are removed 1419 1420 * Unnecessary TRY_FINALLY and TRY_CATCH blocks are removed 1421 1422 * Unnecessary COND_EXPRs are removed 1423 1424 * Some unnecessary BIND_EXPRs are removed 1425 1426 Clearly more work could be done. The trick is doing the analysis 1427 and removal fast enough to be a net improvement in compile times. 1428 1429 Note that when we remove a control structure such as a COND_EXPR 1430 BIND_EXPR, or TRY block, we will need to repeat this optimization pass 1431 to ensure we eliminate all the useless code. */ 1432 1433struct rus_data 1434{ 1435 tree *last_goto; 1436 bool repeat; 1437 bool may_throw; 1438 bool may_branch; 1439 bool has_label; 1440}; 1441 1442static void remove_useless_stmts_1 (tree *, struct rus_data *); 1443 1444static bool 1445remove_useless_stmts_warn_notreached (tree stmt) 1446{ 1447 if (EXPR_HAS_LOCATION (stmt)) 1448 { 1449 location_t loc = EXPR_LOCATION (stmt); 1450 if (LOCATION_LINE (loc) > 0) 1451 { 1452 warning (0, "%Hwill never be executed", &loc); 1453 return true; 1454 } 1455 } 1456 1457 switch (TREE_CODE (stmt)) 1458 { 1459 case STATEMENT_LIST: 1460 { 1461 tree_stmt_iterator i; 1462 for (i = tsi_start (stmt); !tsi_end_p (i); tsi_next (&i)) 1463 if (remove_useless_stmts_warn_notreached (tsi_stmt (i))) 1464 return true; 1465 } 1466 break; 1467 1468 case COND_EXPR: 1469 if (remove_useless_stmts_warn_notreached (COND_EXPR_COND (stmt))) 1470 return true; 1471 if (remove_useless_stmts_warn_notreached (COND_EXPR_THEN (stmt))) 1472 return true; 1473 if (remove_useless_stmts_warn_notreached (COND_EXPR_ELSE (stmt))) 1474 return true; 1475 break; 1476 1477 case TRY_FINALLY_EXPR: 1478 case TRY_CATCH_EXPR: 1479 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt, 0))) 1480 return true; 1481 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt, 1))) 1482 return true; 1483 break; 1484 1485 case CATCH_EXPR: 1486 return remove_useless_stmts_warn_notreached (CATCH_BODY (stmt)); 1487 case EH_FILTER_EXPR: 1488 return remove_useless_stmts_warn_notreached (EH_FILTER_FAILURE (stmt)); 1489 case BIND_EXPR: 1490 return remove_useless_stmts_warn_notreached (BIND_EXPR_BLOCK (stmt)); 1491 1492 default: 1493 /* Not a live container. */ 1494 break; 1495 } 1496 1497 return false; 1498} 1499 1500static void 1501remove_useless_stmts_cond (tree *stmt_p, struct rus_data *data) 1502{ 1503 tree then_clause, else_clause, cond; 1504 bool save_has_label, then_has_label, else_has_label; 1505 1506 save_has_label = data->has_label; 1507 data->has_label = false; 1508 data->last_goto = NULL; 1509 1510 remove_useless_stmts_1 (&COND_EXPR_THEN (*stmt_p), data); 1511 1512 then_has_label = data->has_label; 1513 data->has_label = false; 1514 data->last_goto = NULL; 1515 1516 remove_useless_stmts_1 (&COND_EXPR_ELSE (*stmt_p), data); 1517 1518 else_has_label = data->has_label; 1519 data->has_label = save_has_label | then_has_label | else_has_label; 1520 1521 then_clause = COND_EXPR_THEN (*stmt_p); 1522 else_clause = COND_EXPR_ELSE (*stmt_p); 1523 cond = fold (COND_EXPR_COND (*stmt_p)); 1524 1525 /* If neither arm does anything at all, we can remove the whole IF. */ 1526 if (!TREE_SIDE_EFFECTS (then_clause) && !TREE_SIDE_EFFECTS (else_clause)) 1527 { 1528 *stmt_p = build_empty_stmt (); 1529 data->repeat = true; 1530 } 1531 1532 /* If there are no reachable statements in an arm, then we can 1533 zap the entire conditional. */ 1534 else if (integer_nonzerop (cond) && !else_has_label) 1535 { 1536 if (warn_notreached) 1537 remove_useless_stmts_warn_notreached (else_clause); 1538 *stmt_p = then_clause; 1539 data->repeat = true; 1540 } 1541 else if (integer_zerop (cond) && !then_has_label) 1542 { 1543 if (warn_notreached) 1544 remove_useless_stmts_warn_notreached (then_clause); 1545 *stmt_p = else_clause; 1546 data->repeat = true; 1547 } 1548 1549 /* Check a couple of simple things on then/else with single stmts. */ 1550 else 1551 { 1552 tree then_stmt = expr_only (then_clause); 1553 tree else_stmt = expr_only (else_clause); 1554 1555 /* Notice branches to a common destination. */ 1556 if (then_stmt && else_stmt 1557 && TREE_CODE (then_stmt) == GOTO_EXPR 1558 && TREE_CODE (else_stmt) == GOTO_EXPR 1559 && (GOTO_DESTINATION (then_stmt) == GOTO_DESTINATION (else_stmt))) 1560 { 1561 *stmt_p = then_stmt; 1562 data->repeat = true; 1563 } 1564 1565 /* If the THEN/ELSE clause merely assigns a value to a variable or 1566 parameter which is already known to contain that value, then 1567 remove the useless THEN/ELSE clause. */ 1568 else if (TREE_CODE (cond) == VAR_DECL || TREE_CODE (cond) == PARM_DECL) 1569 { 1570 if (else_stmt 1571 && TREE_CODE (else_stmt) == MODIFY_EXPR 1572 && TREE_OPERAND (else_stmt, 0) == cond 1573 && integer_zerop (TREE_OPERAND (else_stmt, 1))) 1574 COND_EXPR_ELSE (*stmt_p) = alloc_stmt_list (); 1575 } 1576 else if ((TREE_CODE (cond) == EQ_EXPR || TREE_CODE (cond) == NE_EXPR) 1577 && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL 1578 || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL) 1579 && TREE_CONSTANT (TREE_OPERAND (cond, 1))) 1580 { 1581 tree stmt = (TREE_CODE (cond) == EQ_EXPR 1582 ? then_stmt : else_stmt); 1583 tree *location = (TREE_CODE (cond) == EQ_EXPR 1584 ? &COND_EXPR_THEN (*stmt_p) 1585 : &COND_EXPR_ELSE (*stmt_p)); 1586 1587 if (stmt 1588 && TREE_CODE (stmt) == MODIFY_EXPR 1589 && TREE_OPERAND (stmt, 0) == TREE_OPERAND (cond, 0) 1590 && TREE_OPERAND (stmt, 1) == TREE_OPERAND (cond, 1)) 1591 *location = alloc_stmt_list (); 1592 } 1593 } 1594 1595 /* Protect GOTOs in the arm of COND_EXPRs from being removed. They 1596 would be re-introduced during lowering. */ 1597 data->last_goto = NULL; 1598} 1599 1600 1601static void 1602remove_useless_stmts_tf (tree *stmt_p, struct rus_data *data) 1603{ 1604 bool save_may_branch, save_may_throw; 1605 bool this_may_branch, this_may_throw; 1606 1607 /* Collect may_branch and may_throw information for the body only. */ 1608 save_may_branch = data->may_branch; 1609 save_may_throw = data->may_throw; 1610 data->may_branch = false; 1611 data->may_throw = false; 1612 data->last_goto = NULL; 1613 1614 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 0), data); 1615 1616 this_may_branch = data->may_branch; 1617 this_may_throw = data->may_throw; 1618 data->may_branch |= save_may_branch; 1619 data->may_throw |= save_may_throw; 1620 data->last_goto = NULL; 1621 1622 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 1), data); 1623 1624 /* If the body is empty, then we can emit the FINALLY block without 1625 the enclosing TRY_FINALLY_EXPR. */ 1626 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 0))) 1627 { 1628 *stmt_p = TREE_OPERAND (*stmt_p, 1); 1629 data->repeat = true; 1630 } 1631 1632 /* If the handler is empty, then we can emit the TRY block without 1633 the enclosing TRY_FINALLY_EXPR. */ 1634 else if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 1))) 1635 { 1636 *stmt_p = TREE_OPERAND (*stmt_p, 0); 1637 data->repeat = true; 1638 } 1639 1640 /* If the body neither throws, nor branches, then we can safely 1641 string the TRY and FINALLY blocks together. */ 1642 else if (!this_may_branch && !this_may_throw) 1643 { 1644 tree stmt = *stmt_p; 1645 *stmt_p = TREE_OPERAND (stmt, 0); 1646 append_to_statement_list (TREE_OPERAND (stmt, 1), stmt_p); 1647 data->repeat = true; 1648 } 1649} 1650 1651 1652static void 1653remove_useless_stmts_tc (tree *stmt_p, struct rus_data *data) 1654{ 1655 bool save_may_throw, this_may_throw; 1656 tree_stmt_iterator i; 1657 tree stmt; 1658 1659 /* Collect may_throw information for the body only. */ 1660 save_may_throw = data->may_throw; 1661 data->may_throw = false; 1662 data->last_goto = NULL; 1663 1664 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 0), data); 1665 1666 this_may_throw = data->may_throw; 1667 data->may_throw = save_may_throw; 1668 1669 /* If the body cannot throw, then we can drop the entire TRY_CATCH_EXPR. */ 1670 if (!this_may_throw) 1671 { 1672 if (warn_notreached) 1673 remove_useless_stmts_warn_notreached (TREE_OPERAND (*stmt_p, 1)); 1674 *stmt_p = TREE_OPERAND (*stmt_p, 0); 1675 data->repeat = true; 1676 return; 1677 } 1678 1679 /* Process the catch clause specially. We may be able to tell that 1680 no exceptions propagate past this point. */ 1681 1682 this_may_throw = true; 1683 i = tsi_start (TREE_OPERAND (*stmt_p, 1)); 1684 stmt = tsi_stmt (i); 1685 data->last_goto = NULL; 1686 1687 switch (TREE_CODE (stmt)) 1688 { 1689 case CATCH_EXPR: 1690 for (; !tsi_end_p (i); tsi_next (&i)) 1691 { 1692 stmt = tsi_stmt (i); 1693 /* If we catch all exceptions, then the body does not 1694 propagate exceptions past this point. */ 1695 if (CATCH_TYPES (stmt) == NULL) 1696 this_may_throw = false; 1697 data->last_goto = NULL; 1698 remove_useless_stmts_1 (&CATCH_BODY (stmt), data); 1699 } 1700 break; 1701 1702 case EH_FILTER_EXPR: 1703 if (EH_FILTER_MUST_NOT_THROW (stmt)) 1704 this_may_throw = false; 1705 else if (EH_FILTER_TYPES (stmt) == NULL) 1706 this_may_throw = false; 1707 remove_useless_stmts_1 (&EH_FILTER_FAILURE (stmt), data); 1708 break; 1709 1710 default: 1711 /* Otherwise this is a cleanup. */ 1712 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 1), data); 1713 1714 /* If the cleanup is empty, then we can emit the TRY block without 1715 the enclosing TRY_CATCH_EXPR. */ 1716 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 1))) 1717 { 1718 *stmt_p = TREE_OPERAND (*stmt_p, 0); 1719 data->repeat = true; 1720 } 1721 break; 1722 } 1723 data->may_throw |= this_may_throw; 1724} 1725 1726 1727static void 1728remove_useless_stmts_bind (tree *stmt_p, struct rus_data *data) 1729{ 1730 tree block; 1731 1732 /* First remove anything underneath the BIND_EXPR. */ 1733 remove_useless_stmts_1 (&BIND_EXPR_BODY (*stmt_p), data); 1734 1735 /* If the BIND_EXPR has no variables, then we can pull everything 1736 up one level and remove the BIND_EXPR, unless this is the toplevel 1737 BIND_EXPR for the current function or an inlined function. 1738 1739 When this situation occurs we will want to apply this 1740 optimization again. */ 1741 block = BIND_EXPR_BLOCK (*stmt_p); 1742 if (BIND_EXPR_VARS (*stmt_p) == NULL_TREE 1743 && *stmt_p != DECL_SAVED_TREE (current_function_decl) 1744 && (! block 1745 || ! BLOCK_ABSTRACT_ORIGIN (block) 1746 || (TREE_CODE (BLOCK_ABSTRACT_ORIGIN (block)) 1747 != FUNCTION_DECL))) 1748 { 1749 *stmt_p = BIND_EXPR_BODY (*stmt_p); 1750 data->repeat = true; 1751 } 1752} 1753 1754 1755static void 1756remove_useless_stmts_goto (tree *stmt_p, struct rus_data *data) 1757{ 1758 tree dest = GOTO_DESTINATION (*stmt_p); 1759 1760 data->may_branch = true; 1761 data->last_goto = NULL; 1762 1763 /* Record the last goto expr, so that we can delete it if unnecessary. */ 1764 if (TREE_CODE (dest) == LABEL_DECL) 1765 data->last_goto = stmt_p; 1766} 1767 1768 1769static void 1770remove_useless_stmts_label (tree *stmt_p, struct rus_data *data) 1771{ 1772 tree label = LABEL_EXPR_LABEL (*stmt_p); 1773 1774 data->has_label = true; 1775 1776 /* We do want to jump across non-local label receiver code. */ 1777 if (DECL_NONLOCAL (label)) 1778 data->last_goto = NULL; 1779 1780 else if (data->last_goto && GOTO_DESTINATION (*data->last_goto) == label) 1781 { 1782 *data->last_goto = build_empty_stmt (); 1783 data->repeat = true; 1784 } 1785 1786 /* ??? Add something here to delete unused labels. */ 1787} 1788 1789 1790/* If the function is "const" or "pure", then clear TREE_SIDE_EFFECTS on its 1791 decl. This allows us to eliminate redundant or useless 1792 calls to "const" functions. 1793 1794 Gimplifier already does the same operation, but we may notice functions 1795 being const and pure once their calls has been gimplified, so we need 1796 to update the flag. */ 1797 1798static void 1799update_call_expr_flags (tree call) 1800{ 1801 tree decl = get_callee_fndecl (call); 1802 if (!decl) 1803 return; 1804 if (call_expr_flags (call) & (ECF_CONST | ECF_PURE)) 1805 TREE_SIDE_EFFECTS (call) = 0; 1806 if (TREE_NOTHROW (decl)) 1807 TREE_NOTHROW (call) = 1; 1808} 1809 1810 1811/* T is CALL_EXPR. Set current_function_calls_* flags. */ 1812 1813void 1814notice_special_calls (tree t) 1815{ 1816 int flags = call_expr_flags (t); 1817 1818 if (flags & ECF_MAY_BE_ALLOCA) 1819 current_function_calls_alloca = true; 1820 if (flags & ECF_RETURNS_TWICE) 1821 current_function_calls_setjmp = true; 1822} 1823 1824 1825/* Clear flags set by notice_special_calls. Used by dead code removal 1826 to update the flags. */ 1827 1828void 1829clear_special_calls (void) 1830{ 1831 current_function_calls_alloca = false; 1832 current_function_calls_setjmp = false; 1833} 1834 1835 1836static void 1837remove_useless_stmts_1 (tree *tp, struct rus_data *data) 1838{ 1839 tree t = *tp, op; 1840 1841 switch (TREE_CODE (t)) 1842 { 1843 case COND_EXPR: 1844 remove_useless_stmts_cond (tp, data); 1845 break; 1846 1847 case TRY_FINALLY_EXPR: 1848 remove_useless_stmts_tf (tp, data); 1849 break; 1850 1851 case TRY_CATCH_EXPR: 1852 remove_useless_stmts_tc (tp, data); 1853 break; 1854 1855 case BIND_EXPR: 1856 remove_useless_stmts_bind (tp, data); 1857 break; 1858 1859 case GOTO_EXPR: 1860 remove_useless_stmts_goto (tp, data); 1861 break; 1862 1863 case LABEL_EXPR: 1864 remove_useless_stmts_label (tp, data); 1865 break; 1866 1867 case RETURN_EXPR: 1868 fold_stmt (tp); 1869 data->last_goto = NULL; 1870 data->may_branch = true; 1871 break; 1872 1873 case CALL_EXPR: 1874 fold_stmt (tp); 1875 data->last_goto = NULL; 1876 notice_special_calls (t); 1877 update_call_expr_flags (t); 1878 if (tree_could_throw_p (t)) 1879 data->may_throw = true; 1880 break; 1881 1882 case MODIFY_EXPR: 1883 data->last_goto = NULL; 1884 fold_stmt (tp); 1885 op = get_call_expr_in (t); 1886 if (op) 1887 { 1888 update_call_expr_flags (op); 1889 notice_special_calls (op); 1890 } 1891 if (tree_could_throw_p (t)) 1892 data->may_throw = true; 1893 break; 1894 1895 case STATEMENT_LIST: 1896 { 1897 tree_stmt_iterator i = tsi_start (t); 1898 while (!tsi_end_p (i)) 1899 { 1900 t = tsi_stmt (i); 1901 if (IS_EMPTY_STMT (t)) 1902 { 1903 tsi_delink (&i); 1904 continue; 1905 } 1906 1907 remove_useless_stmts_1 (tsi_stmt_ptr (i), data); 1908 1909 t = tsi_stmt (i); 1910 if (TREE_CODE (t) == STATEMENT_LIST) 1911 { 1912 tsi_link_before (&i, t, TSI_SAME_STMT); 1913 tsi_delink (&i); 1914 } 1915 else 1916 tsi_next (&i); 1917 } 1918 } 1919 break; 1920 case ASM_EXPR: 1921 fold_stmt (tp); 1922 data->last_goto = NULL; 1923 break; 1924 1925 default: 1926 data->last_goto = NULL; 1927 break; 1928 } 1929} 1930 1931static unsigned int 1932remove_useless_stmts (void) 1933{ 1934 struct rus_data data; 1935 1936 clear_special_calls (); 1937 1938 do 1939 { 1940 memset (&data, 0, sizeof (data)); 1941 remove_useless_stmts_1 (&DECL_SAVED_TREE (current_function_decl), &data); 1942 } 1943 while (data.repeat); 1944 return 0; 1945} 1946 1947 1948struct tree_opt_pass pass_remove_useless_stmts = 1949{ 1950 "useless", /* name */ 1951 NULL, /* gate */ 1952 remove_useless_stmts, /* execute */ 1953 NULL, /* sub */ 1954 NULL, /* next */ 1955 0, /* static_pass_number */ 1956 0, /* tv_id */ 1957 PROP_gimple_any, /* properties_required */ 1958 0, /* properties_provided */ 1959 0, /* properties_destroyed */ 1960 0, /* todo_flags_start */ 1961 TODO_dump_func, /* todo_flags_finish */ 1962 0 /* letter */ 1963}; 1964 1965/* Remove PHI nodes associated with basic block BB and all edges out of BB. */ 1966 1967static void 1968remove_phi_nodes_and_edges_for_unreachable_block (basic_block bb) 1969{ 1970 tree phi; 1971 1972 /* Since this block is no longer reachable, we can just delete all 1973 of its PHI nodes. */ 1974 phi = phi_nodes (bb); 1975 while (phi) 1976 { 1977 tree next = PHI_CHAIN (phi); 1978 remove_phi_node (phi, NULL_TREE); 1979 phi = next; 1980 } 1981 1982 /* Remove edges to BB's successors. */ 1983 while (EDGE_COUNT (bb->succs) > 0) 1984 remove_edge (EDGE_SUCC (bb, 0)); 1985} 1986 1987 1988/* Remove statements of basic block BB. */ 1989 1990static void 1991remove_bb (basic_block bb) 1992{ 1993 block_stmt_iterator i; 1994#ifdef USE_MAPPED_LOCATION 1995 source_location loc = UNKNOWN_LOCATION; 1996#else 1997 source_locus loc = 0; 1998#endif 1999 2000 if (dump_file) 2001 { 2002 fprintf (dump_file, "Removing basic block %d\n", bb->index); 2003 if (dump_flags & TDF_DETAILS) 2004 { 2005 dump_bb (bb, dump_file, 0); 2006 fprintf (dump_file, "\n"); 2007 } 2008 } 2009 2010 /* If we remove the header or the latch of a loop, mark the loop for 2011 removal by setting its header and latch to NULL. */ 2012 if (current_loops) 2013 { 2014 struct loop *loop = bb->loop_father; 2015 2016 if (loop->latch == bb 2017 || loop->header == bb) 2018 { 2019 loop->latch = NULL; 2020 loop->header = NULL; 2021 2022 /* Also clean up the information associated with the loop. Updating 2023 it would waste time. More importantly, it may refer to ssa 2024 names that were defined in other removed basic block -- these 2025 ssa names are now removed and invalid. */ 2026 free_numbers_of_iterations_estimates_loop (loop); 2027 } 2028 } 2029 2030 /* Remove all the instructions in the block. */ 2031 for (i = bsi_start (bb); !bsi_end_p (i);) 2032 { 2033 tree stmt = bsi_stmt (i); 2034 if (TREE_CODE (stmt) == LABEL_EXPR 2035 && (FORCED_LABEL (LABEL_EXPR_LABEL (stmt)) 2036 || DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)))) 2037 { 2038 basic_block new_bb; 2039 block_stmt_iterator new_bsi; 2040 2041 /* A non-reachable non-local label may still be referenced. 2042 But it no longer needs to carry the extra semantics of 2043 non-locality. */ 2044 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt))) 2045 { 2046 DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)) = 0; 2047 FORCED_LABEL (LABEL_EXPR_LABEL (stmt)) = 1; 2048 } 2049 2050 new_bb = bb->prev_bb; 2051 new_bsi = bsi_start (new_bb); 2052 bsi_remove (&i, false); 2053 bsi_insert_before (&new_bsi, stmt, BSI_NEW_STMT); 2054 } 2055 else 2056 { 2057 /* Release SSA definitions if we are in SSA. Note that we 2058 may be called when not in SSA. For example, 2059 final_cleanup calls this function via 2060 cleanup_tree_cfg. */ 2061 if (in_ssa_p) 2062 release_defs (stmt); 2063 2064 bsi_remove (&i, true); 2065 } 2066 2067 /* Don't warn for removed gotos. Gotos are often removed due to 2068 jump threading, thus resulting in bogus warnings. Not great, 2069 since this way we lose warnings for gotos in the original 2070 program that are indeed unreachable. */ 2071 if (TREE_CODE (stmt) != GOTO_EXPR && EXPR_HAS_LOCATION (stmt) && !loc) 2072 { 2073#ifdef USE_MAPPED_LOCATION 2074 if (EXPR_HAS_LOCATION (stmt)) 2075 loc = EXPR_LOCATION (stmt); 2076#else 2077 source_locus t; 2078 t = EXPR_LOCUS (stmt); 2079 if (t && LOCATION_LINE (*t) > 0) 2080 loc = t; 2081#endif 2082 } 2083 } 2084 2085 /* If requested, give a warning that the first statement in the 2086 block is unreachable. We walk statements backwards in the 2087 loop above, so the last statement we process is the first statement 2088 in the block. */ 2089#ifdef USE_MAPPED_LOCATION 2090 if (loc > BUILTINS_LOCATION) 2091 warning (OPT_Wunreachable_code, "%Hwill never be executed", &loc); 2092#else 2093 if (loc) 2094 warning (OPT_Wunreachable_code, "%Hwill never be executed", loc); 2095#endif 2096 2097 remove_phi_nodes_and_edges_for_unreachable_block (bb); 2098} 2099 2100 2101/* Given a basic block BB ending with COND_EXPR or SWITCH_EXPR, and a 2102 predicate VAL, return the edge that will be taken out of the block. 2103 If VAL does not match a unique edge, NULL is returned. */ 2104 2105edge 2106find_taken_edge (basic_block bb, tree val) 2107{ 2108 tree stmt; 2109 2110 stmt = last_stmt (bb); 2111 2112 gcc_assert (stmt); 2113 gcc_assert (is_ctrl_stmt (stmt)); 2114 gcc_assert (val); 2115 2116 if (! is_gimple_min_invariant (val)) 2117 return NULL; 2118 2119 if (TREE_CODE (stmt) == COND_EXPR) 2120 return find_taken_edge_cond_expr (bb, val); 2121 2122 if (TREE_CODE (stmt) == SWITCH_EXPR) 2123 return find_taken_edge_switch_expr (bb, val); 2124 2125 if (computed_goto_p (stmt)) 2126 { 2127 /* Only optimize if the argument is a label, if the argument is 2128 not a label then we can not construct a proper CFG. 2129 2130 It may be the case that we only need to allow the LABEL_REF to 2131 appear inside an ADDR_EXPR, but we also allow the LABEL_REF to 2132 appear inside a LABEL_EXPR just to be safe. */ 2133 if ((TREE_CODE (val) == ADDR_EXPR || TREE_CODE (val) == LABEL_EXPR) 2134 && TREE_CODE (TREE_OPERAND (val, 0)) == LABEL_DECL) 2135 return find_taken_edge_computed_goto (bb, TREE_OPERAND (val, 0)); 2136 return NULL; 2137 } 2138 2139 gcc_unreachable (); 2140} 2141 2142/* Given a constant value VAL and the entry block BB to a GOTO_EXPR 2143 statement, determine which of the outgoing edges will be taken out of the 2144 block. Return NULL if either edge may be taken. */ 2145 2146static edge 2147find_taken_edge_computed_goto (basic_block bb, tree val) 2148{ 2149 basic_block dest; 2150 edge e = NULL; 2151 2152 dest = label_to_block (val); 2153 if (dest) 2154 { 2155 e = find_edge (bb, dest); 2156 gcc_assert (e != NULL); 2157 } 2158 2159 return e; 2160} 2161 2162/* Given a constant value VAL and the entry block BB to a COND_EXPR 2163 statement, determine which of the two edges will be taken out of the 2164 block. Return NULL if either edge may be taken. */ 2165 2166static edge 2167find_taken_edge_cond_expr (basic_block bb, tree val) 2168{ 2169 edge true_edge, false_edge; 2170 2171 extract_true_false_edges_from_block (bb, &true_edge, &false_edge); 2172 2173 gcc_assert (TREE_CODE (val) == INTEGER_CST); 2174 return (zero_p (val) ? false_edge : true_edge); 2175} 2176 2177/* Given an INTEGER_CST VAL and the entry block BB to a SWITCH_EXPR 2178 statement, determine which edge will be taken out of the block. Return 2179 NULL if any edge may be taken. */ 2180 2181static edge 2182find_taken_edge_switch_expr (basic_block bb, tree val) 2183{ 2184 tree switch_expr, taken_case; 2185 basic_block dest_bb; 2186 edge e; 2187 2188 switch_expr = last_stmt (bb); 2189 taken_case = find_case_label_for_value (switch_expr, val); 2190 dest_bb = label_to_block (CASE_LABEL (taken_case)); 2191 2192 e = find_edge (bb, dest_bb); 2193 gcc_assert (e); 2194 return e; 2195} 2196 2197 2198/* Return the CASE_LABEL_EXPR that SWITCH_EXPR will take for VAL. 2199 We can make optimal use here of the fact that the case labels are 2200 sorted: We can do a binary search for a case matching VAL. */ 2201 2202static tree 2203find_case_label_for_value (tree switch_expr, tree val) 2204{ 2205 tree vec = SWITCH_LABELS (switch_expr); 2206 size_t low, high, n = TREE_VEC_LENGTH (vec); 2207 tree default_case = TREE_VEC_ELT (vec, n - 1); 2208 2209 for (low = -1, high = n - 1; high - low > 1; ) 2210 { 2211 size_t i = (high + low) / 2; 2212 tree t = TREE_VEC_ELT (vec, i); 2213 int cmp; 2214 2215 /* Cache the result of comparing CASE_LOW and val. */ 2216 cmp = tree_int_cst_compare (CASE_LOW (t), val); 2217 2218 if (cmp > 0) 2219 high = i; 2220 else 2221 low = i; 2222 2223 if (CASE_HIGH (t) == NULL) 2224 { 2225 /* A singe-valued case label. */ 2226 if (cmp == 0) 2227 return t; 2228 } 2229 else 2230 { 2231 /* A case range. We can only handle integer ranges. */ 2232 if (cmp <= 0 && tree_int_cst_compare (CASE_HIGH (t), val) >= 0) 2233 return t; 2234 } 2235 } 2236 2237 return default_case; 2238} 2239 2240 2241 2242 2243/*--------------------------------------------------------------------------- 2244 Debugging functions 2245---------------------------------------------------------------------------*/ 2246 2247/* Dump tree-specific information of block BB to file OUTF. */ 2248 2249void 2250tree_dump_bb (basic_block bb, FILE *outf, int indent) 2251{ 2252 dump_generic_bb (outf, bb, indent, TDF_VOPS); 2253} 2254 2255 2256/* Dump a basic block on stderr. */ 2257 2258void 2259debug_tree_bb (basic_block bb) 2260{ 2261 dump_bb (bb, stderr, 0); 2262} 2263 2264 2265/* Dump basic block with index N on stderr. */ 2266 2267basic_block 2268debug_tree_bb_n (int n) 2269{ 2270 debug_tree_bb (BASIC_BLOCK (n)); 2271 return BASIC_BLOCK (n); 2272} 2273 2274 2275/* Dump the CFG on stderr. 2276 2277 FLAGS are the same used by the tree dumping functions 2278 (see TDF_* in tree-pass.h). */ 2279 2280void 2281debug_tree_cfg (int flags) 2282{ 2283 dump_tree_cfg (stderr, flags); 2284} 2285 2286 2287/* Dump the program showing basic block boundaries on the given FILE. 2288 2289 FLAGS are the same used by the tree dumping functions (see TDF_* in 2290 tree.h). */ 2291 2292void 2293dump_tree_cfg (FILE *file, int flags) 2294{ 2295 if (flags & TDF_DETAILS) 2296 { 2297 const char *funcname 2298 = lang_hooks.decl_printable_name (current_function_decl, 2); 2299 2300 fputc ('\n', file); 2301 fprintf (file, ";; Function %s\n\n", funcname); 2302 fprintf (file, ";; \n%d basic blocks, %d edges, last basic block %d.\n\n", 2303 n_basic_blocks, n_edges, last_basic_block); 2304 2305 brief_dump_cfg (file); 2306 fprintf (file, "\n"); 2307 } 2308 2309 if (flags & TDF_STATS) 2310 dump_cfg_stats (file); 2311 2312 dump_function_to_file (current_function_decl, file, flags | TDF_BLOCKS); 2313} 2314 2315 2316/* Dump CFG statistics on FILE. */ 2317 2318void 2319dump_cfg_stats (FILE *file) 2320{ 2321 static long max_num_merged_labels = 0; 2322 unsigned long size, total = 0; 2323 long num_edges; 2324 basic_block bb; 2325 const char * const fmt_str = "%-30s%-13s%12s\n"; 2326 const char * const fmt_str_1 = "%-30s%13d%11lu%c\n"; 2327 const char * const fmt_str_2 = "%-30s%13ld%11lu%c\n"; 2328 const char * const fmt_str_3 = "%-43s%11lu%c\n"; 2329 const char *funcname 2330 = lang_hooks.decl_printable_name (current_function_decl, 2); 2331 2332 2333 fprintf (file, "\nCFG Statistics for %s\n\n", funcname); 2334 2335 fprintf (file, "---------------------------------------------------------\n"); 2336 fprintf (file, fmt_str, "", " Number of ", "Memory"); 2337 fprintf (file, fmt_str, "", " instances ", "used "); 2338 fprintf (file, "---------------------------------------------------------\n"); 2339 2340 size = n_basic_blocks * sizeof (struct basic_block_def); 2341 total += size; 2342 fprintf (file, fmt_str_1, "Basic blocks", n_basic_blocks, 2343 SCALE (size), LABEL (size)); 2344 2345 num_edges = 0; 2346 FOR_EACH_BB (bb) 2347 num_edges += EDGE_COUNT (bb->succs); 2348 size = num_edges * sizeof (struct edge_def); 2349 total += size; 2350 fprintf (file, fmt_str_2, "Edges", num_edges, SCALE (size), LABEL (size)); 2351 2352 fprintf (file, "---------------------------------------------------------\n"); 2353 fprintf (file, fmt_str_3, "Total memory used by CFG data", SCALE (total), 2354 LABEL (total)); 2355 fprintf (file, "---------------------------------------------------------\n"); 2356 fprintf (file, "\n"); 2357 2358 if (cfg_stats.num_merged_labels > max_num_merged_labels) 2359 max_num_merged_labels = cfg_stats.num_merged_labels; 2360 2361 fprintf (file, "Coalesced label blocks: %ld (Max so far: %ld)\n", 2362 cfg_stats.num_merged_labels, max_num_merged_labels); 2363 2364 fprintf (file, "\n"); 2365} 2366 2367 2368/* Dump CFG statistics on stderr. Keep extern so that it's always 2369 linked in the final executable. */ 2370 2371void 2372debug_cfg_stats (void) 2373{ 2374 dump_cfg_stats (stderr); 2375} 2376 2377 2378/* Dump the flowgraph to a .vcg FILE. */ 2379 2380static void 2381tree_cfg2vcg (FILE *file) 2382{ 2383 edge e; 2384 edge_iterator ei; 2385 basic_block bb; 2386 const char *funcname 2387 = lang_hooks.decl_printable_name (current_function_decl, 2); 2388 2389 /* Write the file header. */ 2390 fprintf (file, "graph: { title: \"%s\"\n", funcname); 2391 fprintf (file, "node: { title: \"ENTRY\" label: \"ENTRY\" }\n"); 2392 fprintf (file, "node: { title: \"EXIT\" label: \"EXIT\" }\n"); 2393 2394 /* Write blocks and edges. */ 2395 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs) 2396 { 2397 fprintf (file, "edge: { sourcename: \"ENTRY\" targetname: \"%d\"", 2398 e->dest->index); 2399 2400 if (e->flags & EDGE_FAKE) 2401 fprintf (file, " linestyle: dotted priority: 10"); 2402 else 2403 fprintf (file, " linestyle: solid priority: 100"); 2404 2405 fprintf (file, " }\n"); 2406 } 2407 fputc ('\n', file); 2408 2409 FOR_EACH_BB (bb) 2410 { 2411 enum tree_code head_code, end_code; 2412 const char *head_name, *end_name; 2413 int head_line = 0; 2414 int end_line = 0; 2415 tree first = first_stmt (bb); 2416 tree last = last_stmt (bb); 2417 2418 if (first) 2419 { 2420 head_code = TREE_CODE (first); 2421 head_name = tree_code_name[head_code]; 2422 head_line = get_lineno (first); 2423 } 2424 else 2425 head_name = "no-statement"; 2426 2427 if (last) 2428 { 2429 end_code = TREE_CODE (last); 2430 end_name = tree_code_name[end_code]; 2431 end_line = get_lineno (last); 2432 } 2433 else 2434 end_name = "no-statement"; 2435 2436 fprintf (file, "node: { title: \"%d\" label: \"#%d\\n%s (%d)\\n%s (%d)\"}\n", 2437 bb->index, bb->index, head_name, head_line, end_name, 2438 end_line); 2439 2440 FOR_EACH_EDGE (e, ei, bb->succs) 2441 { 2442 if (e->dest == EXIT_BLOCK_PTR) 2443 fprintf (file, "edge: { sourcename: \"%d\" targetname: \"EXIT\"", bb->index); 2444 else 2445 fprintf (file, "edge: { sourcename: \"%d\" targetname: \"%d\"", bb->index, e->dest->index); 2446 2447 if (e->flags & EDGE_FAKE) 2448 fprintf (file, " priority: 10 linestyle: dotted"); 2449 else 2450 fprintf (file, " priority: 100 linestyle: solid"); 2451 2452 fprintf (file, " }\n"); 2453 } 2454 2455 if (bb->next_bb != EXIT_BLOCK_PTR) 2456 fputc ('\n', file); 2457 } 2458 2459 fputs ("}\n\n", file); 2460} 2461 2462 2463 2464/*--------------------------------------------------------------------------- 2465 Miscellaneous helpers 2466---------------------------------------------------------------------------*/ 2467 2468/* Return true if T represents a stmt that always transfers control. */ 2469 2470bool 2471is_ctrl_stmt (tree t) 2472{ 2473 return (TREE_CODE (t) == COND_EXPR 2474 || TREE_CODE (t) == SWITCH_EXPR 2475 || TREE_CODE (t) == GOTO_EXPR 2476 || TREE_CODE (t) == RETURN_EXPR 2477 || TREE_CODE (t) == RESX_EXPR); 2478} 2479 2480 2481/* Return true if T is a statement that may alter the flow of control 2482 (e.g., a call to a non-returning function). */ 2483 2484bool 2485is_ctrl_altering_stmt (tree t) 2486{ 2487 tree call; 2488 2489 gcc_assert (t); 2490 call = get_call_expr_in (t); 2491 if (call) 2492 { 2493 /* A non-pure/const CALL_EXPR alters flow control if the current 2494 function has nonlocal labels. */ 2495 if (TREE_SIDE_EFFECTS (call) && current_function_has_nonlocal_label) 2496 return true; 2497 2498 /* A CALL_EXPR also alters control flow if it does not return. */ 2499 if (call_expr_flags (call) & ECF_NORETURN) 2500 return true; 2501 } 2502 2503 /* OpenMP directives alter control flow. */ 2504 if (OMP_DIRECTIVE_P (t)) 2505 return true; 2506 2507 /* If a statement can throw, it alters control flow. */ 2508 return tree_can_throw_internal (t); 2509} 2510 2511 2512/* Return true if T is a computed goto. */ 2513 2514bool 2515computed_goto_p (tree t) 2516{ 2517 return (TREE_CODE (t) == GOTO_EXPR 2518 && TREE_CODE (GOTO_DESTINATION (t)) != LABEL_DECL); 2519} 2520 2521 2522/* Return true if T is a simple local goto. */ 2523 2524bool 2525simple_goto_p (tree t) 2526{ 2527 return (TREE_CODE (t) == GOTO_EXPR 2528 && TREE_CODE (GOTO_DESTINATION (t)) == LABEL_DECL); 2529} 2530 2531 2532/* Return true if T can make an abnormal transfer of control flow. 2533 Transfers of control flow associated with EH are excluded. */ 2534 2535bool 2536tree_can_make_abnormal_goto (tree t) 2537{ 2538 if (computed_goto_p (t)) 2539 return true; 2540 if (TREE_CODE (t) == MODIFY_EXPR) 2541 t = TREE_OPERAND (t, 1); 2542 if (TREE_CODE (t) == WITH_SIZE_EXPR) 2543 t = TREE_OPERAND (t, 0); 2544 if (TREE_CODE (t) == CALL_EXPR) 2545 return TREE_SIDE_EFFECTS (t) && current_function_has_nonlocal_label; 2546 return false; 2547} 2548 2549 2550/* Return true if T should start a new basic block. PREV_T is the 2551 statement preceding T. It is used when T is a label or a case label. 2552 Labels should only start a new basic block if their previous statement 2553 wasn't a label. Otherwise, sequence of labels would generate 2554 unnecessary basic blocks that only contain a single label. */ 2555 2556static inline bool 2557stmt_starts_bb_p (tree t, tree prev_t) 2558{ 2559 if (t == NULL_TREE) 2560 return false; 2561 2562 /* LABEL_EXPRs start a new basic block only if the preceding 2563 statement wasn't a label of the same type. This prevents the 2564 creation of consecutive blocks that have nothing but a single 2565 label. */ 2566 if (TREE_CODE (t) == LABEL_EXPR) 2567 { 2568 /* Nonlocal and computed GOTO targets always start a new block. */ 2569 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (t)) 2570 || FORCED_LABEL (LABEL_EXPR_LABEL (t))) 2571 return true; 2572 2573 if (prev_t && TREE_CODE (prev_t) == LABEL_EXPR) 2574 { 2575 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (prev_t))) 2576 return true; 2577 2578 cfg_stats.num_merged_labels++; 2579 return false; 2580 } 2581 else 2582 return true; 2583 } 2584 2585 return false; 2586} 2587 2588 2589/* Return true if T should end a basic block. */ 2590 2591bool 2592stmt_ends_bb_p (tree t) 2593{ 2594 return is_ctrl_stmt (t) || is_ctrl_altering_stmt (t); 2595} 2596 2597 2598/* Add gotos that used to be represented implicitly in the CFG. */ 2599 2600void 2601disband_implicit_edges (void) 2602{ 2603 basic_block bb; 2604 block_stmt_iterator last; 2605 edge e; 2606 edge_iterator ei; 2607 tree stmt, label; 2608 2609 FOR_EACH_BB (bb) 2610 { 2611 last = bsi_last (bb); 2612 stmt = last_stmt (bb); 2613 2614 if (stmt && TREE_CODE (stmt) == COND_EXPR) 2615 { 2616 /* Remove superfluous gotos from COND_EXPR branches. Moved 2617 from cfg_remove_useless_stmts here since it violates the 2618 invariants for tree--cfg correspondence and thus fits better 2619 here where we do it anyway. */ 2620 e = find_edge (bb, bb->next_bb); 2621 if (e) 2622 { 2623 if (e->flags & EDGE_TRUE_VALUE) 2624 COND_EXPR_THEN (stmt) = build_empty_stmt (); 2625 else if (e->flags & EDGE_FALSE_VALUE) 2626 COND_EXPR_ELSE (stmt) = build_empty_stmt (); 2627 else 2628 gcc_unreachable (); 2629 e->flags |= EDGE_FALLTHRU; 2630 } 2631 2632 continue; 2633 } 2634 2635 if (stmt && TREE_CODE (stmt) == RETURN_EXPR) 2636 { 2637 /* Remove the RETURN_EXPR if we may fall though to the exit 2638 instead. */ 2639 gcc_assert (single_succ_p (bb)); 2640 gcc_assert (single_succ (bb) == EXIT_BLOCK_PTR); 2641 2642 if (bb->next_bb == EXIT_BLOCK_PTR 2643 && !TREE_OPERAND (stmt, 0)) 2644 { 2645 bsi_remove (&last, true); 2646 single_succ_edge (bb)->flags |= EDGE_FALLTHRU; 2647 } 2648 continue; 2649 } 2650 2651 /* There can be no fallthru edge if the last statement is a control 2652 one. */ 2653 if (stmt && is_ctrl_stmt (stmt)) 2654 continue; 2655 2656 /* Find a fallthru edge and emit the goto if necessary. */ 2657 FOR_EACH_EDGE (e, ei, bb->succs) 2658 if (e->flags & EDGE_FALLTHRU) 2659 break; 2660 2661 if (!e || e->dest == bb->next_bb) 2662 continue; 2663 2664 gcc_assert (e->dest != EXIT_BLOCK_PTR); 2665 label = tree_block_label (e->dest); 2666 2667 stmt = build1 (GOTO_EXPR, void_type_node, label); 2668#ifdef USE_MAPPED_LOCATION 2669 SET_EXPR_LOCATION (stmt, e->goto_locus); 2670#else 2671 SET_EXPR_LOCUS (stmt, e->goto_locus); 2672#endif 2673 bsi_insert_after (&last, stmt, BSI_NEW_STMT); 2674 e->flags &= ~EDGE_FALLTHRU; 2675 } 2676} 2677 2678/* Remove block annotations and other datastructures. */ 2679 2680void 2681delete_tree_cfg_annotations (void) 2682{ 2683 label_to_block_map = NULL; 2684} 2685 2686 2687/* Return the first statement in basic block BB. */ 2688 2689tree 2690first_stmt (basic_block bb) 2691{ 2692 block_stmt_iterator i = bsi_start (bb); 2693 return !bsi_end_p (i) ? bsi_stmt (i) : NULL_TREE; 2694} 2695 2696 2697/* Return the last statement in basic block BB. */ 2698 2699tree 2700last_stmt (basic_block bb) 2701{ 2702 block_stmt_iterator b = bsi_last (bb); 2703 return !bsi_end_p (b) ? bsi_stmt (b) : NULL_TREE; 2704} 2705 2706 2707/* Return a pointer to the last statement in block BB. */ 2708 2709tree * 2710last_stmt_ptr (basic_block bb) 2711{ 2712 block_stmt_iterator last = bsi_last (bb); 2713 return !bsi_end_p (last) ? bsi_stmt_ptr (last) : NULL; 2714} 2715 2716 2717/* Return the last statement of an otherwise empty block. Return NULL 2718 if the block is totally empty, or if it contains more than one 2719 statement. */ 2720 2721tree 2722last_and_only_stmt (basic_block bb) 2723{ 2724 block_stmt_iterator i = bsi_last (bb); 2725 tree last, prev; 2726 2727 if (bsi_end_p (i)) 2728 return NULL_TREE; 2729 2730 last = bsi_stmt (i); 2731 bsi_prev (&i); 2732 if (bsi_end_p (i)) 2733 return last; 2734 2735 /* Empty statements should no longer appear in the instruction stream. 2736 Everything that might have appeared before should be deleted by 2737 remove_useless_stmts, and the optimizers should just bsi_remove 2738 instead of smashing with build_empty_stmt. 2739 2740 Thus the only thing that should appear here in a block containing 2741 one executable statement is a label. */ 2742 prev = bsi_stmt (i); 2743 if (TREE_CODE (prev) == LABEL_EXPR) 2744 return last; 2745 else 2746 return NULL_TREE; 2747} 2748 2749 2750/* Mark BB as the basic block holding statement T. */ 2751 2752void 2753set_bb_for_stmt (tree t, basic_block bb) 2754{ 2755 if (TREE_CODE (t) == PHI_NODE) 2756 PHI_BB (t) = bb; 2757 else if (TREE_CODE (t) == STATEMENT_LIST) 2758 { 2759 tree_stmt_iterator i; 2760 for (i = tsi_start (t); !tsi_end_p (i); tsi_next (&i)) 2761 set_bb_for_stmt (tsi_stmt (i), bb); 2762 } 2763 else 2764 { 2765 stmt_ann_t ann = get_stmt_ann (t); 2766 ann->bb = bb; 2767 2768 /* If the statement is a label, add the label to block-to-labels map 2769 so that we can speed up edge creation for GOTO_EXPRs. */ 2770 if (TREE_CODE (t) == LABEL_EXPR) 2771 { 2772 int uid; 2773 2774 t = LABEL_EXPR_LABEL (t); 2775 uid = LABEL_DECL_UID (t); 2776 if (uid == -1) 2777 { 2778 unsigned old_len = VEC_length (basic_block, label_to_block_map); 2779 LABEL_DECL_UID (t) = uid = cfun->last_label_uid++; 2780 if (old_len <= (unsigned) uid) 2781 { 2782 basic_block *addr; 2783 unsigned new_len = 3 * uid / 2; 2784 2785 VEC_safe_grow (basic_block, gc, label_to_block_map, 2786 new_len); 2787 addr = VEC_address (basic_block, label_to_block_map); 2788 memset (&addr[old_len], 2789 0, sizeof (basic_block) * (new_len - old_len)); 2790 } 2791 } 2792 else 2793 /* We're moving an existing label. Make sure that we've 2794 removed it from the old block. */ 2795 gcc_assert (!bb 2796 || !VEC_index (basic_block, label_to_block_map, uid)); 2797 VEC_replace (basic_block, label_to_block_map, uid, bb); 2798 } 2799 } 2800} 2801 2802/* Faster version of set_bb_for_stmt that assume that statement is being moved 2803 from one basic block to another. 2804 For BB splitting we can run into quadratic case, so performance is quite 2805 important and knowing that the tables are big enough, change_bb_for_stmt 2806 can inline as leaf function. */ 2807static inline void 2808change_bb_for_stmt (tree t, basic_block bb) 2809{ 2810 get_stmt_ann (t)->bb = bb; 2811 if (TREE_CODE (t) == LABEL_EXPR) 2812 VEC_replace (basic_block, label_to_block_map, 2813 LABEL_DECL_UID (LABEL_EXPR_LABEL (t)), bb); 2814} 2815 2816/* Finds iterator for STMT. */ 2817 2818extern block_stmt_iterator 2819bsi_for_stmt (tree stmt) 2820{ 2821 block_stmt_iterator bsi; 2822 2823 for (bsi = bsi_start (bb_for_stmt (stmt)); !bsi_end_p (bsi); bsi_next (&bsi)) 2824 if (bsi_stmt (bsi) == stmt) 2825 return bsi; 2826 2827 gcc_unreachable (); 2828} 2829 2830/* Mark statement T as modified, and update it. */ 2831static inline void 2832update_modified_stmts (tree t) 2833{ 2834 if (TREE_CODE (t) == STATEMENT_LIST) 2835 { 2836 tree_stmt_iterator i; 2837 tree stmt; 2838 for (i = tsi_start (t); !tsi_end_p (i); tsi_next (&i)) 2839 { 2840 stmt = tsi_stmt (i); 2841 update_stmt_if_modified (stmt); 2842 } 2843 } 2844 else 2845 update_stmt_if_modified (t); 2846} 2847 2848/* Insert statement (or statement list) T before the statement 2849 pointed-to by iterator I. M specifies how to update iterator I 2850 after insertion (see enum bsi_iterator_update). */ 2851 2852void 2853bsi_insert_before (block_stmt_iterator *i, tree t, enum bsi_iterator_update m) 2854{ 2855 set_bb_for_stmt (t, i->bb); 2856 update_modified_stmts (t); 2857 tsi_link_before (&i->tsi, t, (enum tsi_iterator_update) m); 2858} 2859 2860 2861/* Insert statement (or statement list) T after the statement 2862 pointed-to by iterator I. M specifies how to update iterator I 2863 after insertion (see enum bsi_iterator_update). */ 2864 2865void 2866bsi_insert_after (block_stmt_iterator *i, tree t, enum bsi_iterator_update m) 2867{ 2868 set_bb_for_stmt (t, i->bb); 2869 update_modified_stmts (t); 2870 tsi_link_after (&i->tsi, t, (enum tsi_iterator_update) m); 2871} 2872 2873 2874/* Remove the statement pointed to by iterator I. The iterator is updated 2875 to the next statement. 2876 2877 When REMOVE_EH_INFO is true we remove the statement pointed to by 2878 iterator I from the EH tables. Otherwise we do not modify the EH 2879 tables. 2880 2881 Generally, REMOVE_EH_INFO should be true when the statement is going to 2882 be removed from the IL and not reinserted elsewhere. */ 2883 2884void 2885bsi_remove (block_stmt_iterator *i, bool remove_eh_info) 2886{ 2887 tree t = bsi_stmt (*i); 2888 set_bb_for_stmt (t, NULL); 2889 delink_stmt_imm_use (t); 2890 tsi_delink (&i->tsi); 2891 mark_stmt_modified (t); 2892 if (remove_eh_info) 2893 remove_stmt_from_eh_region (t); 2894} 2895 2896 2897/* Move the statement at FROM so it comes right after the statement at TO. */ 2898 2899void 2900bsi_move_after (block_stmt_iterator *from, block_stmt_iterator *to) 2901{ 2902 tree stmt = bsi_stmt (*from); 2903 bsi_remove (from, false); 2904 bsi_insert_after (to, stmt, BSI_SAME_STMT); 2905} 2906 2907 2908/* Move the statement at FROM so it comes right before the statement at TO. */ 2909 2910void 2911bsi_move_before (block_stmt_iterator *from, block_stmt_iterator *to) 2912{ 2913 tree stmt = bsi_stmt (*from); 2914 bsi_remove (from, false); 2915 bsi_insert_before (to, stmt, BSI_SAME_STMT); 2916} 2917 2918 2919/* Move the statement at FROM to the end of basic block BB. */ 2920 2921void 2922bsi_move_to_bb_end (block_stmt_iterator *from, basic_block bb) 2923{ 2924 block_stmt_iterator last = bsi_last (bb); 2925 2926 /* Have to check bsi_end_p because it could be an empty block. */ 2927 if (!bsi_end_p (last) && is_ctrl_stmt (bsi_stmt (last))) 2928 bsi_move_before (from, &last); 2929 else 2930 bsi_move_after (from, &last); 2931} 2932 2933 2934/* Replace the contents of the statement pointed to by iterator BSI 2935 with STMT. If UPDATE_EH_INFO is true, the exception handling 2936 information of the original statement is moved to the new statement. */ 2937 2938void 2939bsi_replace (const block_stmt_iterator *bsi, tree stmt, bool update_eh_info) 2940{ 2941 int eh_region; 2942 tree orig_stmt = bsi_stmt (*bsi); 2943 2944 SET_EXPR_LOCUS (stmt, EXPR_LOCUS (orig_stmt)); 2945 set_bb_for_stmt (stmt, bsi->bb); 2946 2947 /* Preserve EH region information from the original statement, if 2948 requested by the caller. */ 2949 if (update_eh_info) 2950 { 2951 eh_region = lookup_stmt_eh_region (orig_stmt); 2952 if (eh_region >= 0) 2953 { 2954 remove_stmt_from_eh_region (orig_stmt); 2955 add_stmt_to_eh_region (stmt, eh_region); 2956 } 2957 } 2958 2959 delink_stmt_imm_use (orig_stmt); 2960 *bsi_stmt_ptr (*bsi) = stmt; 2961 mark_stmt_modified (stmt); 2962 update_modified_stmts (stmt); 2963} 2964 2965 2966/* Insert the statement pointed-to by BSI into edge E. Every attempt 2967 is made to place the statement in an existing basic block, but 2968 sometimes that isn't possible. When it isn't possible, the edge is 2969 split and the statement is added to the new block. 2970 2971 In all cases, the returned *BSI points to the correct location. The 2972 return value is true if insertion should be done after the location, 2973 or false if it should be done before the location. If new basic block 2974 has to be created, it is stored in *NEW_BB. */ 2975 2976static bool 2977tree_find_edge_insert_loc (edge e, block_stmt_iterator *bsi, 2978 basic_block *new_bb) 2979{ 2980 basic_block dest, src; 2981 tree tmp; 2982 2983 dest = e->dest; 2984 restart: 2985 2986 /* If the destination has one predecessor which has no PHI nodes, 2987 insert there. Except for the exit block. 2988 2989 The requirement for no PHI nodes could be relaxed. Basically we 2990 would have to examine the PHIs to prove that none of them used 2991 the value set by the statement we want to insert on E. That 2992 hardly seems worth the effort. */ 2993 if (single_pred_p (dest) 2994 && ! phi_nodes (dest) 2995 && dest != EXIT_BLOCK_PTR) 2996 { 2997 *bsi = bsi_start (dest); 2998 if (bsi_end_p (*bsi)) 2999 return true; 3000 3001 /* Make sure we insert after any leading labels. */ 3002 tmp = bsi_stmt (*bsi); 3003 while (TREE_CODE (tmp) == LABEL_EXPR) 3004 { 3005 bsi_next (bsi); 3006 if (bsi_end_p (*bsi)) 3007 break; 3008 tmp = bsi_stmt (*bsi); 3009 } 3010 3011 if (bsi_end_p (*bsi)) 3012 { 3013 *bsi = bsi_last (dest); 3014 return true; 3015 } 3016 else 3017 return false; 3018 } 3019 3020 /* If the source has one successor, the edge is not abnormal and 3021 the last statement does not end a basic block, insert there. 3022 Except for the entry block. */ 3023 src = e->src; 3024 if ((e->flags & EDGE_ABNORMAL) == 0 3025 && single_succ_p (src) 3026 && src != ENTRY_BLOCK_PTR) 3027 { 3028 *bsi = bsi_last (src); 3029 if (bsi_end_p (*bsi)) 3030 return true; 3031 3032 tmp = bsi_stmt (*bsi); 3033 if (!stmt_ends_bb_p (tmp)) 3034 return true; 3035 3036 /* Insert code just before returning the value. We may need to decompose 3037 the return in the case it contains non-trivial operand. */ 3038 if (TREE_CODE (tmp) == RETURN_EXPR) 3039 { 3040 tree op = TREE_OPERAND (tmp, 0); 3041 if (op && !is_gimple_val (op)) 3042 { 3043 gcc_assert (TREE_CODE (op) == MODIFY_EXPR); 3044 bsi_insert_before (bsi, op, BSI_NEW_STMT); 3045 TREE_OPERAND (tmp, 0) = TREE_OPERAND (op, 0); 3046 } 3047 bsi_prev (bsi); 3048 return true; 3049 } 3050 } 3051 3052 /* Otherwise, create a new basic block, and split this edge. */ 3053 dest = split_edge (e); 3054 if (new_bb) 3055 *new_bb = dest; 3056 e = single_pred_edge (dest); 3057 goto restart; 3058} 3059 3060 3061/* This routine will commit all pending edge insertions, creating any new 3062 basic blocks which are necessary. */ 3063 3064void 3065bsi_commit_edge_inserts (void) 3066{ 3067 basic_block bb; 3068 edge e; 3069 edge_iterator ei; 3070 3071 bsi_commit_one_edge_insert (single_succ_edge (ENTRY_BLOCK_PTR), NULL); 3072 3073 FOR_EACH_BB (bb) 3074 FOR_EACH_EDGE (e, ei, bb->succs) 3075 bsi_commit_one_edge_insert (e, NULL); 3076} 3077 3078 3079/* Commit insertions pending at edge E. If a new block is created, set NEW_BB 3080 to this block, otherwise set it to NULL. */ 3081 3082void 3083bsi_commit_one_edge_insert (edge e, basic_block *new_bb) 3084{ 3085 if (new_bb) 3086 *new_bb = NULL; 3087 if (PENDING_STMT (e)) 3088 { 3089 block_stmt_iterator bsi; 3090 tree stmt = PENDING_STMT (e); 3091 3092 PENDING_STMT (e) = NULL_TREE; 3093 3094 if (tree_find_edge_insert_loc (e, &bsi, new_bb)) 3095 bsi_insert_after (&bsi, stmt, BSI_NEW_STMT); 3096 else 3097 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT); 3098 } 3099} 3100 3101 3102/* Add STMT to the pending list of edge E. No actual insertion is 3103 made until a call to bsi_commit_edge_inserts () is made. */ 3104 3105void 3106bsi_insert_on_edge (edge e, tree stmt) 3107{ 3108 append_to_statement_list (stmt, &PENDING_STMT (e)); 3109} 3110 3111/* Similar to bsi_insert_on_edge+bsi_commit_edge_inserts. If a new 3112 block has to be created, it is returned. */ 3113 3114basic_block 3115bsi_insert_on_edge_immediate (edge e, tree stmt) 3116{ 3117 block_stmt_iterator bsi; 3118 basic_block new_bb = NULL; 3119 3120 gcc_assert (!PENDING_STMT (e)); 3121 3122 if (tree_find_edge_insert_loc (e, &bsi, &new_bb)) 3123 bsi_insert_after (&bsi, stmt, BSI_NEW_STMT); 3124 else 3125 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT); 3126 3127 return new_bb; 3128} 3129 3130/*--------------------------------------------------------------------------- 3131 Tree specific functions for CFG manipulation 3132---------------------------------------------------------------------------*/ 3133 3134/* Reinstall those PHI arguments queued in OLD_EDGE to NEW_EDGE. */ 3135 3136static void 3137reinstall_phi_args (edge new_edge, edge old_edge) 3138{ 3139 tree var, phi; 3140 3141 if (!PENDING_STMT (old_edge)) 3142 return; 3143 3144 for (var = PENDING_STMT (old_edge), phi = phi_nodes (new_edge->dest); 3145 var && phi; 3146 var = TREE_CHAIN (var), phi = PHI_CHAIN (phi)) 3147 { 3148 tree result = TREE_PURPOSE (var); 3149 tree arg = TREE_VALUE (var); 3150 3151 gcc_assert (result == PHI_RESULT (phi)); 3152 3153 add_phi_arg (phi, arg, new_edge); 3154 } 3155 3156 PENDING_STMT (old_edge) = NULL; 3157} 3158 3159/* Returns the basic block after which the new basic block created 3160 by splitting edge EDGE_IN should be placed. Tries to keep the new block 3161 near its "logical" location. This is of most help to humans looking 3162 at debugging dumps. */ 3163 3164static basic_block 3165split_edge_bb_loc (edge edge_in) 3166{ 3167 basic_block dest = edge_in->dest; 3168 3169 if (dest->prev_bb && find_edge (dest->prev_bb, dest)) 3170 return edge_in->src; 3171 else 3172 return dest->prev_bb; 3173} 3174 3175/* Split a (typically critical) edge EDGE_IN. Return the new block. 3176 Abort on abnormal edges. */ 3177 3178static basic_block 3179tree_split_edge (edge edge_in) 3180{ 3181 basic_block new_bb, after_bb, dest; 3182 edge new_edge, e; 3183 3184 /* Abnormal edges cannot be split. */ 3185 gcc_assert (!(edge_in->flags & EDGE_ABNORMAL)); 3186 3187 dest = edge_in->dest; 3188 3189 after_bb = split_edge_bb_loc (edge_in); 3190 3191 new_bb = create_empty_bb (after_bb); 3192 new_bb->frequency = EDGE_FREQUENCY (edge_in); 3193 new_bb->count = edge_in->count; 3194 new_edge = make_edge (new_bb, dest, EDGE_FALLTHRU); 3195 new_edge->probability = REG_BR_PROB_BASE; 3196 new_edge->count = edge_in->count; 3197 3198 e = redirect_edge_and_branch (edge_in, new_bb); 3199 gcc_assert (e); 3200 reinstall_phi_args (new_edge, e); 3201 3202 return new_bb; 3203} 3204 3205 3206/* Return true when BB has label LABEL in it. */ 3207 3208static bool 3209has_label_p (basic_block bb, tree label) 3210{ 3211 block_stmt_iterator bsi; 3212 3213 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi)) 3214 { 3215 tree stmt = bsi_stmt (bsi); 3216 3217 if (TREE_CODE (stmt) != LABEL_EXPR) 3218 return false; 3219 if (LABEL_EXPR_LABEL (stmt) == label) 3220 return true; 3221 } 3222 return false; 3223} 3224 3225 3226/* Callback for walk_tree, check that all elements with address taken are 3227 properly noticed as such. The DATA is an int* that is 1 if TP was seen 3228 inside a PHI node. */ 3229 3230static tree 3231verify_expr (tree *tp, int *walk_subtrees, void *data ATTRIBUTE_UNUSED) 3232{ 3233 tree t = *tp, x; 3234 bool in_phi = (data != NULL); 3235 3236 if (TYPE_P (t)) 3237 *walk_subtrees = 0; 3238 3239 /* Check operand N for being valid GIMPLE and give error MSG if not. */ 3240#define CHECK_OP(N, MSG) \ 3241 do { if (!is_gimple_val (TREE_OPERAND (t, N))) \ 3242 { error (MSG); return TREE_OPERAND (t, N); }} while (0) 3243 3244 switch (TREE_CODE (t)) 3245 { 3246 case SSA_NAME: 3247 if (SSA_NAME_IN_FREE_LIST (t)) 3248 { 3249 error ("SSA name in freelist but still referenced"); 3250 return *tp; 3251 } 3252 break; 3253 3254 case ASSERT_EXPR: 3255 x = fold (ASSERT_EXPR_COND (t)); 3256 if (x == boolean_false_node) 3257 { 3258 error ("ASSERT_EXPR with an always-false condition"); 3259 return *tp; 3260 } 3261 break; 3262 3263 case MODIFY_EXPR: 3264 x = TREE_OPERAND (t, 0); 3265 if (TREE_CODE (x) == BIT_FIELD_REF 3266 && is_gimple_reg (TREE_OPERAND (x, 0))) 3267 { 3268 error ("GIMPLE register modified with BIT_FIELD_REF"); 3269 return t; 3270 } 3271 break; 3272 3273 case ADDR_EXPR: 3274 { 3275 bool old_invariant; 3276 bool old_constant; 3277 bool old_side_effects; 3278 bool new_invariant; 3279 bool new_constant; 3280 bool new_side_effects; 3281 3282 /* ??? tree-ssa-alias.c may have overlooked dead PHI nodes, missing 3283 dead PHIs that take the address of something. But if the PHI 3284 result is dead, the fact that it takes the address of anything 3285 is irrelevant. Because we can not tell from here if a PHI result 3286 is dead, we just skip this check for PHIs altogether. This means 3287 we may be missing "valid" checks, but what can you do? 3288 This was PR19217. */ 3289 if (in_phi) 3290 break; 3291 3292 old_invariant = TREE_INVARIANT (t); 3293 old_constant = TREE_CONSTANT (t); 3294 old_side_effects = TREE_SIDE_EFFECTS (t); 3295 3296 recompute_tree_invariant_for_addr_expr (t); 3297 new_invariant = TREE_INVARIANT (t); 3298 new_side_effects = TREE_SIDE_EFFECTS (t); 3299 new_constant = TREE_CONSTANT (t); 3300 3301 if (old_invariant != new_invariant) 3302 { 3303 error ("invariant not recomputed when ADDR_EXPR changed"); 3304 return t; 3305 } 3306 3307 if (old_constant != new_constant) 3308 { 3309 error ("constant not recomputed when ADDR_EXPR changed"); 3310 return t; 3311 } 3312 if (old_side_effects != new_side_effects) 3313 { 3314 error ("side effects not recomputed when ADDR_EXPR changed"); 3315 return t; 3316 } 3317 3318 /* Skip any references (they will be checked when we recurse down the 3319 tree) and ensure that any variable used as a prefix is marked 3320 addressable. */ 3321 for (x = TREE_OPERAND (t, 0); 3322 handled_component_p (x); 3323 x = TREE_OPERAND (x, 0)) 3324 ; 3325 3326 if (TREE_CODE (x) != VAR_DECL && TREE_CODE (x) != PARM_DECL) 3327 return NULL; 3328 if (!TREE_ADDRESSABLE (x)) 3329 { 3330 error ("address taken, but ADDRESSABLE bit not set"); 3331 return x; 3332 } 3333 break; 3334 } 3335 3336 case COND_EXPR: 3337 x = COND_EXPR_COND (t); 3338 if (TREE_CODE (TREE_TYPE (x)) != BOOLEAN_TYPE) 3339 { 3340 error ("non-boolean used in condition"); 3341 return x; 3342 } 3343 if (!is_gimple_condexpr (x)) 3344 { 3345 error ("invalid conditional operand"); 3346 return x; 3347 } 3348 break; 3349 3350 case NOP_EXPR: 3351 case CONVERT_EXPR: 3352 case FIX_TRUNC_EXPR: 3353 case FIX_CEIL_EXPR: 3354 case FIX_FLOOR_EXPR: 3355 case FIX_ROUND_EXPR: 3356 case FLOAT_EXPR: 3357 case NEGATE_EXPR: 3358 case ABS_EXPR: 3359 case BIT_NOT_EXPR: 3360 case NON_LVALUE_EXPR: 3361 case TRUTH_NOT_EXPR: 3362 CHECK_OP (0, "invalid operand to unary operator"); 3363 break; 3364 3365 case REALPART_EXPR: 3366 case IMAGPART_EXPR: 3367 case COMPONENT_REF: 3368 case ARRAY_REF: 3369 case ARRAY_RANGE_REF: 3370 case BIT_FIELD_REF: 3371 case VIEW_CONVERT_EXPR: 3372 /* We have a nest of references. Verify that each of the operands 3373 that determine where to reference is either a constant or a variable, 3374 verify that the base is valid, and then show we've already checked 3375 the subtrees. */ 3376 while (handled_component_p (t)) 3377 { 3378 if (TREE_CODE (t) == COMPONENT_REF && TREE_OPERAND (t, 2)) 3379 CHECK_OP (2, "invalid COMPONENT_REF offset operator"); 3380 else if (TREE_CODE (t) == ARRAY_REF 3381 || TREE_CODE (t) == ARRAY_RANGE_REF) 3382 { 3383 CHECK_OP (1, "invalid array index"); 3384 if (TREE_OPERAND (t, 2)) 3385 CHECK_OP (2, "invalid array lower bound"); 3386 if (TREE_OPERAND (t, 3)) 3387 CHECK_OP (3, "invalid array stride"); 3388 } 3389 else if (TREE_CODE (t) == BIT_FIELD_REF) 3390 { 3391 CHECK_OP (1, "invalid operand to BIT_FIELD_REF"); 3392 CHECK_OP (2, "invalid operand to BIT_FIELD_REF"); 3393 } 3394 3395 t = TREE_OPERAND (t, 0); 3396 } 3397 3398 if (!CONSTANT_CLASS_P (t) && !is_gimple_lvalue (t)) 3399 { 3400 error ("invalid reference prefix"); 3401 return t; 3402 } 3403 *walk_subtrees = 0; 3404 break; 3405 3406 case LT_EXPR: 3407 case LE_EXPR: 3408 case GT_EXPR: 3409 case GE_EXPR: 3410 case EQ_EXPR: 3411 case NE_EXPR: 3412 case UNORDERED_EXPR: 3413 case ORDERED_EXPR: 3414 case UNLT_EXPR: 3415 case UNLE_EXPR: 3416 case UNGT_EXPR: 3417 case UNGE_EXPR: 3418 case UNEQ_EXPR: 3419 case LTGT_EXPR: 3420 case PLUS_EXPR: 3421 case MINUS_EXPR: 3422 case MULT_EXPR: 3423 case TRUNC_DIV_EXPR: 3424 case CEIL_DIV_EXPR: 3425 case FLOOR_DIV_EXPR: 3426 case ROUND_DIV_EXPR: 3427 case TRUNC_MOD_EXPR: 3428 case CEIL_MOD_EXPR: 3429 case FLOOR_MOD_EXPR: 3430 case ROUND_MOD_EXPR: 3431 case RDIV_EXPR: 3432 case EXACT_DIV_EXPR: 3433 case MIN_EXPR: 3434 case MAX_EXPR: 3435 case LSHIFT_EXPR: 3436 case RSHIFT_EXPR: 3437 case LROTATE_EXPR: 3438 case RROTATE_EXPR: 3439 case BIT_IOR_EXPR: 3440 case BIT_XOR_EXPR: 3441 case BIT_AND_EXPR: 3442 CHECK_OP (0, "invalid operand to binary operator"); 3443 CHECK_OP (1, "invalid operand to binary operator"); 3444 break; 3445 3446 case CONSTRUCTOR: 3447 if (TREE_CONSTANT (t) && TREE_CODE (TREE_TYPE (t)) == VECTOR_TYPE) 3448 *walk_subtrees = 0; 3449 break; 3450 3451 default: 3452 break; 3453 } 3454 return NULL; 3455 3456#undef CHECK_OP 3457} 3458 3459 3460/* Verify STMT, return true if STMT is not in GIMPLE form. 3461 TODO: Implement type checking. */ 3462 3463static bool 3464verify_stmt (tree stmt, bool last_in_block) 3465{ 3466 tree addr; 3467 3468 if (OMP_DIRECTIVE_P (stmt)) 3469 { 3470 /* OpenMP directives are validated by the FE and never operated 3471 on by the optimizers. Furthermore, OMP_FOR may contain 3472 non-gimple expressions when the main index variable has had 3473 its address taken. This does not affect the loop itself 3474 because the header of an OMP_FOR is merely used to determine 3475 how to setup the parallel iteration. */ 3476 return false; 3477 } 3478 3479 if (!is_gimple_stmt (stmt)) 3480 { 3481 error ("is not a valid GIMPLE statement"); 3482 goto fail; 3483 } 3484 3485 addr = walk_tree (&stmt, verify_expr, NULL, NULL); 3486 if (addr) 3487 { 3488 debug_generic_stmt (addr); 3489 return true; 3490 } 3491 3492 /* If the statement is marked as part of an EH region, then it is 3493 expected that the statement could throw. Verify that when we 3494 have optimizations that simplify statements such that we prove 3495 that they cannot throw, that we update other data structures 3496 to match. */ 3497 if (lookup_stmt_eh_region (stmt) >= 0) 3498 { 3499 if (!tree_could_throw_p (stmt)) 3500 { 3501 error ("statement marked for throw, but doesn%'t"); 3502 goto fail; 3503 } 3504 if (!last_in_block && tree_can_throw_internal (stmt)) 3505 { 3506 error ("statement marked for throw in middle of block"); 3507 goto fail; 3508 } 3509 } 3510 3511 return false; 3512 3513 fail: 3514 debug_generic_stmt (stmt); 3515 return true; 3516} 3517 3518 3519/* Return true when the T can be shared. */ 3520 3521static bool 3522tree_node_can_be_shared (tree t) 3523{ 3524 if (IS_TYPE_OR_DECL_P (t) 3525 || is_gimple_min_invariant (t) 3526 || TREE_CODE (t) == SSA_NAME 3527 || t == error_mark_node 3528 || TREE_CODE (t) == IDENTIFIER_NODE) 3529 return true; 3530 3531 if (TREE_CODE (t) == CASE_LABEL_EXPR) 3532 return true; 3533 3534 while (((TREE_CODE (t) == ARRAY_REF || TREE_CODE (t) == ARRAY_RANGE_REF) 3535 && is_gimple_min_invariant (TREE_OPERAND (t, 1))) 3536 || TREE_CODE (t) == COMPONENT_REF 3537 || TREE_CODE (t) == REALPART_EXPR 3538 || TREE_CODE (t) == IMAGPART_EXPR) 3539 t = TREE_OPERAND (t, 0); 3540 3541 if (DECL_P (t)) 3542 return true; 3543 3544 return false; 3545} 3546 3547 3548/* Called via walk_trees. Verify tree sharing. */ 3549 3550static tree 3551verify_node_sharing (tree * tp, int *walk_subtrees, void *data) 3552{ 3553 htab_t htab = (htab_t) data; 3554 void **slot; 3555 3556 if (tree_node_can_be_shared (*tp)) 3557 { 3558 *walk_subtrees = false; 3559 return NULL; 3560 } 3561 3562 slot = htab_find_slot (htab, *tp, INSERT); 3563 if (*slot) 3564 return (tree) *slot; 3565 *slot = *tp; 3566 3567 return NULL; 3568} 3569 3570 3571/* Verify the GIMPLE statement chain. */ 3572 3573void 3574verify_stmts (void) 3575{ 3576 basic_block bb; 3577 block_stmt_iterator bsi; 3578 bool err = false; 3579 htab_t htab; 3580 tree addr; 3581 3582 timevar_push (TV_TREE_STMT_VERIFY); 3583 htab = htab_create (37, htab_hash_pointer, htab_eq_pointer, NULL); 3584 3585 FOR_EACH_BB (bb) 3586 { 3587 tree phi; 3588 int i; 3589 3590 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi)) 3591 { 3592 int phi_num_args = PHI_NUM_ARGS (phi); 3593 3594 if (bb_for_stmt (phi) != bb) 3595 { 3596 error ("bb_for_stmt (phi) is set to a wrong basic block"); 3597 err |= true; 3598 } 3599 3600 for (i = 0; i < phi_num_args; i++) 3601 { 3602 tree t = PHI_ARG_DEF (phi, i); 3603 tree addr; 3604 3605 /* Addressable variables do have SSA_NAMEs but they 3606 are not considered gimple values. */ 3607 if (TREE_CODE (t) != SSA_NAME 3608 && TREE_CODE (t) != FUNCTION_DECL 3609 && !is_gimple_val (t)) 3610 { 3611 error ("PHI def is not a GIMPLE value"); 3612 debug_generic_stmt (phi); 3613 debug_generic_stmt (t); 3614 err |= true; 3615 } 3616 3617 addr = walk_tree (&t, verify_expr, (void *) 1, NULL); 3618 if (addr) 3619 { 3620 debug_generic_stmt (addr); 3621 err |= true; 3622 } 3623 3624 addr = walk_tree (&t, verify_node_sharing, htab, NULL); 3625 if (addr) 3626 { 3627 error ("incorrect sharing of tree nodes"); 3628 debug_generic_stmt (phi); 3629 debug_generic_stmt (addr); 3630 err |= true; 3631 } 3632 } 3633 } 3634 3635 for (bsi = bsi_start (bb); !bsi_end_p (bsi); ) 3636 { 3637 tree stmt = bsi_stmt (bsi); 3638 3639 if (bb_for_stmt (stmt) != bb) 3640 { 3641 error ("bb_for_stmt (stmt) is set to a wrong basic block"); 3642 err |= true; 3643 } 3644 3645 bsi_next (&bsi); 3646 err |= verify_stmt (stmt, bsi_end_p (bsi)); 3647 addr = walk_tree (&stmt, verify_node_sharing, htab, NULL); 3648 if (addr) 3649 { 3650 error ("incorrect sharing of tree nodes"); 3651 debug_generic_stmt (stmt); 3652 debug_generic_stmt (addr); 3653 err |= true; 3654 } 3655 } 3656 } 3657 3658 if (err) 3659 internal_error ("verify_stmts failed"); 3660 3661 htab_delete (htab); 3662 timevar_pop (TV_TREE_STMT_VERIFY); 3663} 3664 3665 3666/* Verifies that the flow information is OK. */ 3667 3668static int 3669tree_verify_flow_info (void) 3670{ 3671 int err = 0; 3672 basic_block bb; 3673 block_stmt_iterator bsi; 3674 tree stmt; 3675 edge e; 3676 edge_iterator ei; 3677 3678 if (ENTRY_BLOCK_PTR->stmt_list) 3679 { 3680 error ("ENTRY_BLOCK has a statement list associated with it"); 3681 err = 1; 3682 } 3683 3684 if (EXIT_BLOCK_PTR->stmt_list) 3685 { 3686 error ("EXIT_BLOCK has a statement list associated with it"); 3687 err = 1; 3688 } 3689 3690 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds) 3691 if (e->flags & EDGE_FALLTHRU) 3692 { 3693 error ("fallthru to exit from bb %d", e->src->index); 3694 err = 1; 3695 } 3696 3697 FOR_EACH_BB (bb) 3698 { 3699 bool found_ctrl_stmt = false; 3700 3701 stmt = NULL_TREE; 3702 3703 /* Skip labels on the start of basic block. */ 3704 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi)) 3705 { 3706 tree prev_stmt = stmt; 3707 3708 stmt = bsi_stmt (bsi); 3709 3710 if (TREE_CODE (stmt) != LABEL_EXPR) 3711 break; 3712 3713 if (prev_stmt && DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt))) 3714 { 3715 error ("nonlocal label "); 3716 print_generic_expr (stderr, LABEL_EXPR_LABEL (stmt), 0); 3717 fprintf (stderr, " is not first in a sequence of labels in bb %d", 3718 bb->index); 3719 err = 1; 3720 } 3721 3722 if (label_to_block (LABEL_EXPR_LABEL (stmt)) != bb) 3723 { 3724 error ("label "); 3725 print_generic_expr (stderr, LABEL_EXPR_LABEL (stmt), 0); 3726 fprintf (stderr, " to block does not match in bb %d", 3727 bb->index); 3728 err = 1; 3729 } 3730 3731 if (decl_function_context (LABEL_EXPR_LABEL (stmt)) 3732 != current_function_decl) 3733 { 3734 error ("label "); 3735 print_generic_expr (stderr, LABEL_EXPR_LABEL (stmt), 0); 3736 fprintf (stderr, " has incorrect context in bb %d", 3737 bb->index); 3738 err = 1; 3739 } 3740 } 3741 3742 /* Verify that body of basic block BB is free of control flow. */ 3743 for (; !bsi_end_p (bsi); bsi_next (&bsi)) 3744 { 3745 tree stmt = bsi_stmt (bsi); 3746 3747 if (found_ctrl_stmt) 3748 { 3749 error ("control flow in the middle of basic block %d", 3750 bb->index); 3751 err = 1; 3752 } 3753 3754 if (stmt_ends_bb_p (stmt)) 3755 found_ctrl_stmt = true; 3756 3757 if (TREE_CODE (stmt) == LABEL_EXPR) 3758 { 3759 error ("label "); 3760 print_generic_expr (stderr, LABEL_EXPR_LABEL (stmt), 0); 3761 fprintf (stderr, " in the middle of basic block %d", bb->index); 3762 err = 1; 3763 } 3764 } 3765 3766 bsi = bsi_last (bb); 3767 if (bsi_end_p (bsi)) 3768 continue; 3769 3770 stmt = bsi_stmt (bsi); 3771 3772 err |= verify_eh_edges (stmt); 3773 3774 if (is_ctrl_stmt (stmt)) 3775 { 3776 FOR_EACH_EDGE (e, ei, bb->succs) 3777 if (e->flags & EDGE_FALLTHRU) 3778 { 3779 error ("fallthru edge after a control statement in bb %d", 3780 bb->index); 3781 err = 1; 3782 } 3783 } 3784 3785 if (TREE_CODE (stmt) != COND_EXPR) 3786 { 3787 /* Verify that there are no edges with EDGE_TRUE/FALSE_FLAG set 3788 after anything else but if statement. */ 3789 FOR_EACH_EDGE (e, ei, bb->succs) 3790 if (e->flags & (EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)) 3791 { 3792 error ("true/false edge after a non-COND_EXPR in bb %d", 3793 bb->index); 3794 err = 1; 3795 } 3796 } 3797 3798 switch (TREE_CODE (stmt)) 3799 { 3800 case COND_EXPR: 3801 { 3802 edge true_edge; 3803 edge false_edge; 3804 if (TREE_CODE (COND_EXPR_THEN (stmt)) != GOTO_EXPR 3805 || TREE_CODE (COND_EXPR_ELSE (stmt)) != GOTO_EXPR) 3806 { 3807 error ("structured COND_EXPR at the end of bb %d", bb->index); 3808 err = 1; 3809 } 3810 3811 extract_true_false_edges_from_block (bb, &true_edge, &false_edge); 3812 3813 if (!true_edge || !false_edge 3814 || !(true_edge->flags & EDGE_TRUE_VALUE) 3815 || !(false_edge->flags & EDGE_FALSE_VALUE) 3816 || (true_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL)) 3817 || (false_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL)) 3818 || EDGE_COUNT (bb->succs) >= 3) 3819 { 3820 error ("wrong outgoing edge flags at end of bb %d", 3821 bb->index); 3822 err = 1; 3823 } 3824 3825 if (!has_label_p (true_edge->dest, 3826 GOTO_DESTINATION (COND_EXPR_THEN (stmt)))) 3827 { 3828 error ("%<then%> label does not match edge at end of bb %d", 3829 bb->index); 3830 err = 1; 3831 } 3832 3833 if (!has_label_p (false_edge->dest, 3834 GOTO_DESTINATION (COND_EXPR_ELSE (stmt)))) 3835 { 3836 error ("%<else%> label does not match edge at end of bb %d", 3837 bb->index); 3838 err = 1; 3839 } 3840 } 3841 break; 3842 3843 case GOTO_EXPR: 3844 if (simple_goto_p (stmt)) 3845 { 3846 error ("explicit goto at end of bb %d", bb->index); 3847 err = 1; 3848 } 3849 else 3850 { 3851 /* FIXME. We should double check that the labels in the 3852 destination blocks have their address taken. */ 3853 FOR_EACH_EDGE (e, ei, bb->succs) 3854 if ((e->flags & (EDGE_FALLTHRU | EDGE_TRUE_VALUE 3855 | EDGE_FALSE_VALUE)) 3856 || !(e->flags & EDGE_ABNORMAL)) 3857 { 3858 error ("wrong outgoing edge flags at end of bb %d", 3859 bb->index); 3860 err = 1; 3861 } 3862 } 3863 break; 3864 3865 case RETURN_EXPR: 3866 if (!single_succ_p (bb) 3867 || (single_succ_edge (bb)->flags 3868 & (EDGE_FALLTHRU | EDGE_ABNORMAL 3869 | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE))) 3870 { 3871 error ("wrong outgoing edge flags at end of bb %d", bb->index); 3872 err = 1; 3873 } 3874 if (single_succ (bb) != EXIT_BLOCK_PTR) 3875 { 3876 error ("return edge does not point to exit in bb %d", 3877 bb->index); 3878 err = 1; 3879 } 3880 break; 3881 3882 case SWITCH_EXPR: 3883 { 3884 tree prev; 3885 edge e; 3886 size_t i, n; 3887 tree vec; 3888 3889 vec = SWITCH_LABELS (stmt); 3890 n = TREE_VEC_LENGTH (vec); 3891 3892 /* Mark all the destination basic blocks. */ 3893 for (i = 0; i < n; ++i) 3894 { 3895 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i)); 3896 basic_block label_bb = label_to_block (lab); 3897 3898 gcc_assert (!label_bb->aux || label_bb->aux == (void *)1); 3899 label_bb->aux = (void *)1; 3900 } 3901 3902 /* Verify that the case labels are sorted. */ 3903 prev = TREE_VEC_ELT (vec, 0); 3904 for (i = 1; i < n - 1; ++i) 3905 { 3906 tree c = TREE_VEC_ELT (vec, i); 3907 if (! CASE_LOW (c)) 3908 { 3909 error ("found default case not at end of case vector"); 3910 err = 1; 3911 continue; 3912 } 3913 if (! tree_int_cst_lt (CASE_LOW (prev), CASE_LOW (c))) 3914 { 3915 error ("case labels not sorted: "); 3916 print_generic_expr (stderr, prev, 0); 3917 fprintf (stderr," is greater than "); 3918 print_generic_expr (stderr, c, 0); 3919 fprintf (stderr," but comes before it.\n"); 3920 err = 1; 3921 } 3922 prev = c; 3923 } 3924 if (CASE_LOW (TREE_VEC_ELT (vec, n - 1))) 3925 { 3926 error ("no default case found at end of case vector"); 3927 err = 1; 3928 } 3929 3930 FOR_EACH_EDGE (e, ei, bb->succs) 3931 { 3932 if (!e->dest->aux) 3933 { 3934 error ("extra outgoing edge %d->%d", 3935 bb->index, e->dest->index); 3936 err = 1; 3937 } 3938 e->dest->aux = (void *)2; 3939 if ((e->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL 3940 | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE))) 3941 { 3942 error ("wrong outgoing edge flags at end of bb %d", 3943 bb->index); 3944 err = 1; 3945 } 3946 } 3947 3948 /* Check that we have all of them. */ 3949 for (i = 0; i < n; ++i) 3950 { 3951 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i)); 3952 basic_block label_bb = label_to_block (lab); 3953 3954 if (label_bb->aux != (void *)2) 3955 { 3956 error ("missing edge %i->%i", 3957 bb->index, label_bb->index); 3958 err = 1; 3959 } 3960 } 3961 3962 FOR_EACH_EDGE (e, ei, bb->succs) 3963 e->dest->aux = (void *)0; 3964 } 3965 3966 default: ; 3967 } 3968 } 3969 3970 if (dom_computed[CDI_DOMINATORS] >= DOM_NO_FAST_QUERY) 3971 verify_dominators (CDI_DOMINATORS); 3972 3973 return err; 3974} 3975 3976 3977/* Updates phi nodes after creating a forwarder block joined 3978 by edge FALLTHRU. */ 3979 3980static void 3981tree_make_forwarder_block (edge fallthru) 3982{ 3983 edge e; 3984 edge_iterator ei; 3985 basic_block dummy, bb; 3986 tree phi, new_phi, var; 3987 3988 dummy = fallthru->src; 3989 bb = fallthru->dest; 3990 3991 if (single_pred_p (bb)) 3992 return; 3993 3994 /* If we redirected a branch we must create new phi nodes at the 3995 start of BB. */ 3996 for (phi = phi_nodes (dummy); phi; phi = PHI_CHAIN (phi)) 3997 { 3998 var = PHI_RESULT (phi); 3999 new_phi = create_phi_node (var, bb); 4000 SSA_NAME_DEF_STMT (var) = new_phi; 4001 SET_PHI_RESULT (phi, make_ssa_name (SSA_NAME_VAR (var), phi)); 4002 add_phi_arg (new_phi, PHI_RESULT (phi), fallthru); 4003 } 4004 4005 /* Ensure that the PHI node chain is in the same order. */ 4006 set_phi_nodes (bb, phi_reverse (phi_nodes (bb))); 4007 4008 /* Add the arguments we have stored on edges. */ 4009 FOR_EACH_EDGE (e, ei, bb->preds) 4010 { 4011 if (e == fallthru) 4012 continue; 4013 4014 flush_pending_stmts (e); 4015 } 4016} 4017 4018 4019/* Return a non-special label in the head of basic block BLOCK. 4020 Create one if it doesn't exist. */ 4021 4022tree 4023tree_block_label (basic_block bb) 4024{ 4025 block_stmt_iterator i, s = bsi_start (bb); 4026 bool first = true; 4027 tree label, stmt; 4028 4029 for (i = s; !bsi_end_p (i); first = false, bsi_next (&i)) 4030 { 4031 stmt = bsi_stmt (i); 4032 if (TREE_CODE (stmt) != LABEL_EXPR) 4033 break; 4034 label = LABEL_EXPR_LABEL (stmt); 4035 if (!DECL_NONLOCAL (label)) 4036 { 4037 if (!first) 4038 bsi_move_before (&i, &s); 4039 return label; 4040 } 4041 } 4042 4043 label = create_artificial_label (); 4044 stmt = build1 (LABEL_EXPR, void_type_node, label); 4045 bsi_insert_before (&s, stmt, BSI_NEW_STMT); 4046 return label; 4047} 4048 4049 4050/* Attempt to perform edge redirection by replacing a possibly complex 4051 jump instruction by a goto or by removing the jump completely. 4052 This can apply only if all edges now point to the same block. The 4053 parameters and return values are equivalent to 4054 redirect_edge_and_branch. */ 4055 4056static edge 4057tree_try_redirect_by_replacing_jump (edge e, basic_block target) 4058{ 4059 basic_block src = e->src; 4060 block_stmt_iterator b; 4061 tree stmt; 4062 4063 /* We can replace or remove a complex jump only when we have exactly 4064 two edges. */ 4065 if (EDGE_COUNT (src->succs) != 2 4066 /* Verify that all targets will be TARGET. Specifically, the 4067 edge that is not E must also go to TARGET. */ 4068 || EDGE_SUCC (src, EDGE_SUCC (src, 0) == e)->dest != target) 4069 return NULL; 4070 4071 b = bsi_last (src); 4072 if (bsi_end_p (b)) 4073 return NULL; 4074 stmt = bsi_stmt (b); 4075 4076 if (TREE_CODE (stmt) == COND_EXPR 4077 || TREE_CODE (stmt) == SWITCH_EXPR) 4078 { 4079 bsi_remove (&b, true); 4080 e = ssa_redirect_edge (e, target); 4081 e->flags = EDGE_FALLTHRU; 4082 return e; 4083 } 4084 4085 return NULL; 4086} 4087 4088 4089/* Redirect E to DEST. Return NULL on failure. Otherwise, return the 4090 edge representing the redirected branch. */ 4091 4092static edge 4093tree_redirect_edge_and_branch (edge e, basic_block dest) 4094{ 4095 basic_block bb = e->src; 4096 block_stmt_iterator bsi; 4097 edge ret; 4098 tree label, stmt; 4099 4100 if (e->flags & EDGE_ABNORMAL) 4101 return NULL; 4102 4103 if (e->src != ENTRY_BLOCK_PTR 4104 && (ret = tree_try_redirect_by_replacing_jump (e, dest))) 4105 return ret; 4106 4107 if (e->dest == dest) 4108 return NULL; 4109 4110 label = tree_block_label (dest); 4111 4112 bsi = bsi_last (bb); 4113 stmt = bsi_end_p (bsi) ? NULL : bsi_stmt (bsi); 4114 4115 switch (stmt ? TREE_CODE (stmt) : ERROR_MARK) 4116 { 4117 case COND_EXPR: 4118 stmt = (e->flags & EDGE_TRUE_VALUE 4119 ? COND_EXPR_THEN (stmt) 4120 : COND_EXPR_ELSE (stmt)); 4121 GOTO_DESTINATION (stmt) = label; 4122 break; 4123 4124 case GOTO_EXPR: 4125 /* No non-abnormal edges should lead from a non-simple goto, and 4126 simple ones should be represented implicitly. */ 4127 gcc_unreachable (); 4128 4129 case SWITCH_EXPR: 4130 { 4131 tree cases = get_cases_for_edge (e, stmt); 4132 4133 /* If we have a list of cases associated with E, then use it 4134 as it's a lot faster than walking the entire case vector. */ 4135 if (cases) 4136 { 4137 edge e2 = find_edge (e->src, dest); 4138 tree last, first; 4139 4140 first = cases; 4141 while (cases) 4142 { 4143 last = cases; 4144 CASE_LABEL (cases) = label; 4145 cases = TREE_CHAIN (cases); 4146 } 4147 4148 /* If there was already an edge in the CFG, then we need 4149 to move all the cases associated with E to E2. */ 4150 if (e2) 4151 { 4152 tree cases2 = get_cases_for_edge (e2, stmt); 4153 4154 TREE_CHAIN (last) = TREE_CHAIN (cases2); 4155 TREE_CHAIN (cases2) = first; 4156 } 4157 } 4158 else 4159 { 4160 tree vec = SWITCH_LABELS (stmt); 4161 size_t i, n = TREE_VEC_LENGTH (vec); 4162 4163 for (i = 0; i < n; i++) 4164 { 4165 tree elt = TREE_VEC_ELT (vec, i); 4166 4167 if (label_to_block (CASE_LABEL (elt)) == e->dest) 4168 CASE_LABEL (elt) = label; 4169 } 4170 } 4171 4172 break; 4173 } 4174 4175 case RETURN_EXPR: 4176 bsi_remove (&bsi, true); 4177 e->flags |= EDGE_FALLTHRU; 4178 break; 4179 4180 default: 4181 /* Otherwise it must be a fallthru edge, and we don't need to 4182 do anything besides redirecting it. */ 4183 gcc_assert (e->flags & EDGE_FALLTHRU); 4184 break; 4185 } 4186 4187 /* Update/insert PHI nodes as necessary. */ 4188 4189 /* Now update the edges in the CFG. */ 4190 e = ssa_redirect_edge (e, dest); 4191 4192 return e; 4193} 4194 4195 4196/* Simple wrapper, as we can always redirect fallthru edges. */ 4197 4198static basic_block 4199tree_redirect_edge_and_branch_force (edge e, basic_block dest) 4200{ 4201 e = tree_redirect_edge_and_branch (e, dest); 4202 gcc_assert (e); 4203 4204 return NULL; 4205} 4206 4207 4208/* Splits basic block BB after statement STMT (but at least after the 4209 labels). If STMT is NULL, BB is split just after the labels. */ 4210 4211static basic_block 4212tree_split_block (basic_block bb, void *stmt) 4213{ 4214 block_stmt_iterator bsi; 4215 tree_stmt_iterator tsi_tgt; 4216 tree act; 4217 basic_block new_bb; 4218 edge e; 4219 edge_iterator ei; 4220 4221 new_bb = create_empty_bb (bb); 4222 4223 /* Redirect the outgoing edges. */ 4224 new_bb->succs = bb->succs; 4225 bb->succs = NULL; 4226 FOR_EACH_EDGE (e, ei, new_bb->succs) 4227 e->src = new_bb; 4228 4229 if (stmt && TREE_CODE ((tree) stmt) == LABEL_EXPR) 4230 stmt = NULL; 4231 4232 /* Move everything from BSI to the new basic block. */ 4233 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi)) 4234 { 4235 act = bsi_stmt (bsi); 4236 if (TREE_CODE (act) == LABEL_EXPR) 4237 continue; 4238 4239 if (!stmt) 4240 break; 4241 4242 if (stmt == act) 4243 { 4244 bsi_next (&bsi); 4245 break; 4246 } 4247 } 4248 4249 if (bsi_end_p (bsi)) 4250 return new_bb; 4251 4252 /* Split the statement list - avoid re-creating new containers as this 4253 brings ugly quadratic memory consumption in the inliner. 4254 (We are still quadratic since we need to update stmt BB pointers, 4255 sadly.) */ 4256 new_bb->stmt_list = tsi_split_statement_list_before (&bsi.tsi); 4257 for (tsi_tgt = tsi_start (new_bb->stmt_list); 4258 !tsi_end_p (tsi_tgt); tsi_next (&tsi_tgt)) 4259 change_bb_for_stmt (tsi_stmt (tsi_tgt), new_bb); 4260 4261 return new_bb; 4262} 4263 4264 4265/* Moves basic block BB after block AFTER. */ 4266 4267static bool 4268tree_move_block_after (basic_block bb, basic_block after) 4269{ 4270 if (bb->prev_bb == after) 4271 return true; 4272 4273 unlink_block (bb); 4274 link_block (bb, after); 4275 4276 return true; 4277} 4278 4279 4280/* Return true if basic_block can be duplicated. */ 4281 4282static bool 4283tree_can_duplicate_bb_p (basic_block bb ATTRIBUTE_UNUSED) 4284{ 4285 return true; 4286} 4287 4288 4289/* Create a duplicate of the basic block BB. NOTE: This does not 4290 preserve SSA form. */ 4291 4292static basic_block 4293tree_duplicate_bb (basic_block bb) 4294{ 4295 basic_block new_bb; 4296 block_stmt_iterator bsi, bsi_tgt; 4297 tree phi; 4298 4299 new_bb = create_empty_bb (EXIT_BLOCK_PTR->prev_bb); 4300 4301 /* Copy the PHI nodes. We ignore PHI node arguments here because 4302 the incoming edges have not been setup yet. */ 4303 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi)) 4304 { 4305 tree copy = create_phi_node (PHI_RESULT (phi), new_bb); 4306 create_new_def_for (PHI_RESULT (copy), copy, PHI_RESULT_PTR (copy)); 4307 } 4308 4309 /* Keep the chain of PHI nodes in the same order so that they can be 4310 updated by ssa_redirect_edge. */ 4311 set_phi_nodes (new_bb, phi_reverse (phi_nodes (new_bb))); 4312 4313 bsi_tgt = bsi_start (new_bb); 4314 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi)) 4315 { 4316 def_operand_p def_p; 4317 ssa_op_iter op_iter; 4318 tree stmt, copy; 4319 int region; 4320 4321 stmt = bsi_stmt (bsi); 4322 if (TREE_CODE (stmt) == LABEL_EXPR) 4323 continue; 4324 4325 /* Create a new copy of STMT and duplicate STMT's virtual 4326 operands. */ 4327 copy = unshare_expr (stmt); 4328 bsi_insert_after (&bsi_tgt, copy, BSI_NEW_STMT); 4329 copy_virtual_operands (copy, stmt); 4330 region = lookup_stmt_eh_region (stmt); 4331 if (region >= 0) 4332 add_stmt_to_eh_region (copy, region); 4333 4334 /* Create new names for all the definitions created by COPY and 4335 add replacement mappings for each new name. */ 4336 FOR_EACH_SSA_DEF_OPERAND (def_p, copy, op_iter, SSA_OP_ALL_DEFS) 4337 create_new_def_for (DEF_FROM_PTR (def_p), copy, def_p); 4338 } 4339 4340 return new_bb; 4341} 4342 4343 4344/* Basic block BB_COPY was created by code duplication. Add phi node 4345 arguments for edges going out of BB_COPY. The blocks that were 4346 duplicated have BB_DUPLICATED set. */ 4347 4348void 4349add_phi_args_after_copy_bb (basic_block bb_copy) 4350{ 4351 basic_block bb, dest; 4352 edge e, e_copy; 4353 edge_iterator ei; 4354 tree phi, phi_copy, phi_next, def; 4355 4356 bb = get_bb_original (bb_copy); 4357 4358 FOR_EACH_EDGE (e_copy, ei, bb_copy->succs) 4359 { 4360 if (!phi_nodes (e_copy->dest)) 4361 continue; 4362 4363 if (e_copy->dest->flags & BB_DUPLICATED) 4364 dest = get_bb_original (e_copy->dest); 4365 else 4366 dest = e_copy->dest; 4367 4368 e = find_edge (bb, dest); 4369 if (!e) 4370 { 4371 /* During loop unrolling the target of the latch edge is copied. 4372 In this case we are not looking for edge to dest, but to 4373 duplicated block whose original was dest. */ 4374 FOR_EACH_EDGE (e, ei, bb->succs) 4375 if ((e->dest->flags & BB_DUPLICATED) 4376 && get_bb_original (e->dest) == dest) 4377 break; 4378 4379 gcc_assert (e != NULL); 4380 } 4381 4382 for (phi = phi_nodes (e->dest), phi_copy = phi_nodes (e_copy->dest); 4383 phi; 4384 phi = phi_next, phi_copy = PHI_CHAIN (phi_copy)) 4385 { 4386 phi_next = PHI_CHAIN (phi); 4387 def = PHI_ARG_DEF_FROM_EDGE (phi, e); 4388 add_phi_arg (phi_copy, def, e_copy); 4389 } 4390 } 4391} 4392 4393/* Blocks in REGION_COPY array of length N_REGION were created by 4394 duplication of basic blocks. Add phi node arguments for edges 4395 going from these blocks. */ 4396 4397void 4398add_phi_args_after_copy (basic_block *region_copy, unsigned n_region) 4399{ 4400 unsigned i; 4401 4402 for (i = 0; i < n_region; i++) 4403 region_copy[i]->flags |= BB_DUPLICATED; 4404 4405 for (i = 0; i < n_region; i++) 4406 add_phi_args_after_copy_bb (region_copy[i]); 4407 4408 for (i = 0; i < n_region; i++) 4409 region_copy[i]->flags &= ~BB_DUPLICATED; 4410} 4411 4412/* Duplicates a REGION (set of N_REGION basic blocks) with just a single 4413 important exit edge EXIT. By important we mean that no SSA name defined 4414 inside region is live over the other exit edges of the region. All entry 4415 edges to the region must go to ENTRY->dest. The edge ENTRY is redirected 4416 to the duplicate of the region. SSA form, dominance and loop information 4417 is updated. The new basic blocks are stored to REGION_COPY in the same 4418 order as they had in REGION, provided that REGION_COPY is not NULL. 4419 The function returns false if it is unable to copy the region, 4420 true otherwise. */ 4421 4422bool 4423tree_duplicate_sese_region (edge entry, edge exit, 4424 basic_block *region, unsigned n_region, 4425 basic_block *region_copy) 4426{ 4427 unsigned i, n_doms; 4428 bool free_region_copy = false, copying_header = false; 4429 struct loop *loop = entry->dest->loop_father; 4430 edge exit_copy; 4431 basic_block *doms; 4432 edge redirected; 4433 int total_freq = 0, entry_freq = 0; 4434 gcov_type total_count = 0, entry_count = 0; 4435 4436 if (!can_copy_bbs_p (region, n_region)) 4437 return false; 4438 4439 /* Some sanity checking. Note that we do not check for all possible 4440 missuses of the functions. I.e. if you ask to copy something weird, 4441 it will work, but the state of structures probably will not be 4442 correct. */ 4443 for (i = 0; i < n_region; i++) 4444 { 4445 /* We do not handle subloops, i.e. all the blocks must belong to the 4446 same loop. */ 4447 if (region[i]->loop_father != loop) 4448 return false; 4449 4450 if (region[i] != entry->dest 4451 && region[i] == loop->header) 4452 return false; 4453 } 4454 4455 loop->copy = loop; 4456 4457 /* In case the function is used for loop header copying (which is the primary 4458 use), ensure that EXIT and its copy will be new latch and entry edges. */ 4459 if (loop->header == entry->dest) 4460 { 4461 copying_header = true; 4462 loop->copy = loop->outer; 4463 4464 if (!dominated_by_p (CDI_DOMINATORS, loop->latch, exit->src)) 4465 return false; 4466 4467 for (i = 0; i < n_region; i++) 4468 if (region[i] != exit->src 4469 && dominated_by_p (CDI_DOMINATORS, region[i], exit->src)) 4470 return false; 4471 } 4472 4473 if (!region_copy) 4474 { 4475 region_copy = XNEWVEC (basic_block, n_region); 4476 free_region_copy = true; 4477 } 4478 4479 gcc_assert (!need_ssa_update_p ()); 4480 4481 /* Record blocks outside the region that are dominated by something 4482 inside. */ 4483 doms = XNEWVEC (basic_block, n_basic_blocks); 4484 initialize_original_copy_tables (); 4485 4486 n_doms = get_dominated_by_region (CDI_DOMINATORS, region, n_region, doms); 4487 4488 if (entry->dest->count) 4489 { 4490 total_count = entry->dest->count; 4491 entry_count = entry->count; 4492 /* Fix up corner cases, to avoid division by zero or creation of negative 4493 frequencies. */ 4494 if (entry_count > total_count) 4495 entry_count = total_count; 4496 } 4497 else 4498 { 4499 total_freq = entry->dest->frequency; 4500 entry_freq = EDGE_FREQUENCY (entry); 4501 /* Fix up corner cases, to avoid division by zero or creation of negative 4502 frequencies. */ 4503 if (total_freq == 0) 4504 total_freq = 1; 4505 else if (entry_freq > total_freq) 4506 entry_freq = total_freq; 4507 } 4508 4509 copy_bbs (region, n_region, region_copy, &exit, 1, &exit_copy, loop, 4510 split_edge_bb_loc (entry)); 4511 if (total_count) 4512 { 4513 scale_bbs_frequencies_gcov_type (region, n_region, 4514 total_count - entry_count, 4515 total_count); 4516 scale_bbs_frequencies_gcov_type (region_copy, n_region, entry_count, 4517 total_count); 4518 } 4519 else 4520 { 4521 scale_bbs_frequencies_int (region, n_region, total_freq - entry_freq, 4522 total_freq); 4523 scale_bbs_frequencies_int (region_copy, n_region, entry_freq, total_freq); 4524 } 4525 4526 if (copying_header) 4527 { 4528 loop->header = exit->dest; 4529 loop->latch = exit->src; 4530 } 4531 4532 /* Redirect the entry and add the phi node arguments. */ 4533 redirected = redirect_edge_and_branch (entry, get_bb_copy (entry->dest)); 4534 gcc_assert (redirected != NULL); 4535 flush_pending_stmts (entry); 4536 4537 /* Concerning updating of dominators: We must recount dominators 4538 for entry block and its copy. Anything that is outside of the 4539 region, but was dominated by something inside needs recounting as 4540 well. */ 4541 set_immediate_dominator (CDI_DOMINATORS, entry->dest, entry->src); 4542 doms[n_doms++] = get_bb_original (entry->dest); 4543 iterate_fix_dominators (CDI_DOMINATORS, doms, n_doms); 4544 free (doms); 4545 4546 /* Add the other PHI node arguments. */ 4547 add_phi_args_after_copy (region_copy, n_region); 4548 4549 /* Update the SSA web. */ 4550 update_ssa (TODO_update_ssa); 4551 4552 if (free_region_copy) 4553 free (region_copy); 4554 4555 free_original_copy_tables (); 4556 return true; 4557} 4558 4559/* 4560DEF_VEC_P(basic_block); 4561DEF_VEC_ALLOC_P(basic_block,heap); 4562*/ 4563 4564/* Add all the blocks dominated by ENTRY to the array BBS_P. Stop 4565 adding blocks when the dominator traversal reaches EXIT. This 4566 function silently assumes that ENTRY strictly dominates EXIT. */ 4567 4568static void 4569gather_blocks_in_sese_region (basic_block entry, basic_block exit, 4570 VEC(basic_block,heap) **bbs_p) 4571{ 4572 basic_block son; 4573 4574 for (son = first_dom_son (CDI_DOMINATORS, entry); 4575 son; 4576 son = next_dom_son (CDI_DOMINATORS, son)) 4577 { 4578 VEC_safe_push (basic_block, heap, *bbs_p, son); 4579 if (son != exit) 4580 gather_blocks_in_sese_region (son, exit, bbs_p); 4581 } 4582} 4583 4584 4585struct move_stmt_d 4586{ 4587 tree block; 4588 tree from_context; 4589 tree to_context; 4590 bitmap vars_to_remove; 4591 htab_t new_label_map; 4592 bool remap_decls_p; 4593}; 4594 4595/* Helper for move_block_to_fn. Set TREE_BLOCK in every expression 4596 contained in *TP and change the DECL_CONTEXT of every local 4597 variable referenced in *TP. */ 4598 4599static tree 4600move_stmt_r (tree *tp, int *walk_subtrees, void *data) 4601{ 4602 struct move_stmt_d *p = (struct move_stmt_d *) data; 4603 tree t = *tp; 4604 4605 if (p->block && IS_EXPR_CODE_CLASS (TREE_CODE_CLASS (TREE_CODE (t)))) 4606 TREE_BLOCK (t) = p->block; 4607 4608 if (OMP_DIRECTIVE_P (t) 4609 && TREE_CODE (t) != OMP_RETURN 4610 && TREE_CODE (t) != OMP_CONTINUE) 4611 { 4612 /* Do not remap variables inside OMP directives. Variables 4613 referenced in clauses and directive header belong to the 4614 parent function and should not be moved into the child 4615 function. */ 4616 bool save_remap_decls_p = p->remap_decls_p; 4617 p->remap_decls_p = false; 4618 *walk_subtrees = 0; 4619 4620 walk_tree (&OMP_BODY (t), move_stmt_r, p, NULL); 4621 4622 p->remap_decls_p = save_remap_decls_p; 4623 } 4624 else if (DECL_P (t) && DECL_CONTEXT (t) == p->from_context) 4625 { 4626 if (TREE_CODE (t) == LABEL_DECL) 4627 { 4628 if (p->new_label_map) 4629 { 4630 struct tree_map in, *out; 4631 in.from = t; 4632 out = htab_find_with_hash (p->new_label_map, &in, DECL_UID (t)); 4633 if (out) 4634 *tp = t = out->to; 4635 } 4636 4637 DECL_CONTEXT (t) = p->to_context; 4638 } 4639 else if (p->remap_decls_p) 4640 { 4641 DECL_CONTEXT (t) = p->to_context; 4642 4643 if (TREE_CODE (t) == VAR_DECL) 4644 { 4645 struct function *f = DECL_STRUCT_FUNCTION (p->to_context); 4646 f->unexpanded_var_list 4647 = tree_cons (0, t, f->unexpanded_var_list); 4648 4649 /* Mark T to be removed from the original function, 4650 otherwise it will be given a DECL_RTL when the 4651 original function is expanded. */ 4652 bitmap_set_bit (p->vars_to_remove, DECL_UID (t)); 4653 } 4654 } 4655 } 4656 else if (TYPE_P (t)) 4657 *walk_subtrees = 0; 4658 4659 return NULL_TREE; 4660} 4661 4662 4663/* Move basic block BB from function CFUN to function DEST_FN. The 4664 block is moved out of the original linked list and placed after 4665 block AFTER in the new list. Also, the block is removed from the 4666 original array of blocks and placed in DEST_FN's array of blocks. 4667 If UPDATE_EDGE_COUNT_P is true, the edge counts on both CFGs is 4668 updated to reflect the moved edges. 4669 4670 On exit, local variables that need to be removed from 4671 CFUN->UNEXPANDED_VAR_LIST will have been added to VARS_TO_REMOVE. */ 4672 4673static void 4674move_block_to_fn (struct function *dest_cfun, basic_block bb, 4675 basic_block after, bool update_edge_count_p, 4676 bitmap vars_to_remove, htab_t new_label_map, int eh_offset) 4677{ 4678 struct control_flow_graph *cfg; 4679 edge_iterator ei; 4680 edge e; 4681 block_stmt_iterator si; 4682 struct move_stmt_d d; 4683 unsigned old_len, new_len; 4684 basic_block *addr; 4685 4686 /* Link BB to the new linked list. */ 4687 move_block_after (bb, after); 4688 4689 /* Update the edge count in the corresponding flowgraphs. */ 4690 if (update_edge_count_p) 4691 FOR_EACH_EDGE (e, ei, bb->succs) 4692 { 4693 cfun->cfg->x_n_edges--; 4694 dest_cfun->cfg->x_n_edges++; 4695 } 4696 4697 /* Remove BB from the original basic block array. */ 4698 VEC_replace (basic_block, cfun->cfg->x_basic_block_info, bb->index, NULL); 4699 cfun->cfg->x_n_basic_blocks--; 4700 4701 /* Grow DEST_CFUN's basic block array if needed. */ 4702 cfg = dest_cfun->cfg; 4703 cfg->x_n_basic_blocks++; 4704 if (bb->index > cfg->x_last_basic_block) 4705 cfg->x_last_basic_block = bb->index; 4706 4707 old_len = VEC_length (basic_block, cfg->x_basic_block_info); 4708 if ((unsigned) cfg->x_last_basic_block >= old_len) 4709 { 4710 new_len = cfg->x_last_basic_block + (cfg->x_last_basic_block + 3) / 4; 4711 VEC_safe_grow (basic_block, gc, cfg->x_basic_block_info, new_len); 4712 addr = VEC_address (basic_block, cfg->x_basic_block_info); 4713 memset (&addr[old_len], 0, sizeof (basic_block) * (new_len - old_len)); 4714 } 4715 4716 VEC_replace (basic_block, cfg->x_basic_block_info, 4717 cfg->x_last_basic_block, bb); 4718 4719 /* The statements in BB need to be associated with a new TREE_BLOCK. 4720 Labels need to be associated with a new label-to-block map. */ 4721 memset (&d, 0, sizeof (d)); 4722 d.vars_to_remove = vars_to_remove; 4723 4724 for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si)) 4725 { 4726 tree stmt = bsi_stmt (si); 4727 int region; 4728 4729 d.from_context = cfun->decl; 4730 d.to_context = dest_cfun->decl; 4731 d.remap_decls_p = true; 4732 d.new_label_map = new_label_map; 4733 if (TREE_BLOCK (stmt)) 4734 d.block = DECL_INITIAL (dest_cfun->decl); 4735 4736 walk_tree (&stmt, move_stmt_r, &d, NULL); 4737 4738 if (TREE_CODE (stmt) == LABEL_EXPR) 4739 { 4740 tree label = LABEL_EXPR_LABEL (stmt); 4741 int uid = LABEL_DECL_UID (label); 4742 4743 gcc_assert (uid > -1); 4744 4745 old_len = VEC_length (basic_block, cfg->x_label_to_block_map); 4746 if (old_len <= (unsigned) uid) 4747 { 4748 new_len = 3 * uid / 2; 4749 VEC_safe_grow (basic_block, gc, cfg->x_label_to_block_map, 4750 new_len); 4751 addr = VEC_address (basic_block, cfg->x_label_to_block_map); 4752 memset (&addr[old_len], 0, 4753 sizeof (basic_block) * (new_len - old_len)); 4754 } 4755 4756 VEC_replace (basic_block, cfg->x_label_to_block_map, uid, bb); 4757 VEC_replace (basic_block, cfun->cfg->x_label_to_block_map, uid, NULL); 4758 4759 gcc_assert (DECL_CONTEXT (label) == dest_cfun->decl); 4760 4761 if (uid >= dest_cfun->last_label_uid) 4762 dest_cfun->last_label_uid = uid + 1; 4763 } 4764 else if (TREE_CODE (stmt) == RESX_EXPR && eh_offset != 0) 4765 TREE_OPERAND (stmt, 0) = 4766 build_int_cst (NULL_TREE, 4767 TREE_INT_CST_LOW (TREE_OPERAND (stmt, 0)) 4768 + eh_offset); 4769 4770 region = lookup_stmt_eh_region (stmt); 4771 if (region >= 0) 4772 { 4773 add_stmt_to_eh_region_fn (dest_cfun, stmt, region + eh_offset); 4774 remove_stmt_from_eh_region (stmt); 4775 } 4776 } 4777} 4778 4779/* Examine the statements in BB (which is in SRC_CFUN); find and return 4780 the outermost EH region. Use REGION as the incoming base EH region. */ 4781 4782static int 4783find_outermost_region_in_block (struct function *src_cfun, 4784 basic_block bb, int region) 4785{ 4786 block_stmt_iterator si; 4787 4788 for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si)) 4789 { 4790 tree stmt = bsi_stmt (si); 4791 int stmt_region; 4792 4793 if (TREE_CODE (stmt) == RESX_EXPR) 4794 stmt_region = TREE_INT_CST_LOW (TREE_OPERAND (stmt, 0)); 4795 else 4796 stmt_region = lookup_stmt_eh_region_fn (src_cfun, stmt); 4797 if (stmt_region > 0) 4798 { 4799 if (region < 0) 4800 region = stmt_region; 4801 else if (stmt_region != region) 4802 { 4803 region = eh_region_outermost (src_cfun, stmt_region, region); 4804 gcc_assert (region != -1); 4805 } 4806 } 4807 } 4808 4809 return region; 4810} 4811 4812static tree 4813new_label_mapper (tree decl, void *data) 4814{ 4815 htab_t hash = (htab_t) data; 4816 struct tree_map *m; 4817 void **slot; 4818 4819 gcc_assert (TREE_CODE (decl) == LABEL_DECL); 4820 4821 m = xmalloc (sizeof (struct tree_map)); 4822 m->hash = DECL_UID (decl); 4823 m->from = decl; 4824 m->to = create_artificial_label (); 4825 LABEL_DECL_UID (m->to) = LABEL_DECL_UID (decl); 4826 4827 slot = htab_find_slot_with_hash (hash, m, m->hash, INSERT); 4828 gcc_assert (*slot == NULL); 4829 4830 *slot = m; 4831 4832 return m->to; 4833} 4834 4835/* Move a single-entry, single-exit region delimited by ENTRY_BB and 4836 EXIT_BB to function DEST_CFUN. The whole region is replaced by a 4837 single basic block in the original CFG and the new basic block is 4838 returned. DEST_CFUN must not have a CFG yet. 4839 4840 Note that the region need not be a pure SESE region. Blocks inside 4841 the region may contain calls to abort/exit. The only restriction 4842 is that ENTRY_BB should be the only entry point and it must 4843 dominate EXIT_BB. 4844 4845 All local variables referenced in the region are assumed to be in 4846 the corresponding BLOCK_VARS and unexpanded variable lists 4847 associated with DEST_CFUN. */ 4848 4849basic_block 4850move_sese_region_to_fn (struct function *dest_cfun, basic_block entry_bb, 4851 basic_block exit_bb) 4852{ 4853 VEC(basic_block,heap) *bbs; 4854 basic_block after, bb, *entry_pred, *exit_succ; 4855 struct function *saved_cfun; 4856 int *entry_flag, *exit_flag, eh_offset; 4857 unsigned i, num_entry_edges, num_exit_edges; 4858 edge e; 4859 edge_iterator ei; 4860 bitmap vars_to_remove; 4861 htab_t new_label_map; 4862 4863 saved_cfun = cfun; 4864 4865 /* Collect all the blocks in the region. Manually add ENTRY_BB 4866 because it won't be added by dfs_enumerate_from. */ 4867 calculate_dominance_info (CDI_DOMINATORS); 4868 4869 /* If ENTRY does not strictly dominate EXIT, this cannot be an SESE 4870 region. */ 4871 gcc_assert (entry_bb != exit_bb 4872 && (!exit_bb 4873 || dominated_by_p (CDI_DOMINATORS, exit_bb, entry_bb))); 4874 4875 bbs = NULL; 4876 VEC_safe_push (basic_block, heap, bbs, entry_bb); 4877 gather_blocks_in_sese_region (entry_bb, exit_bb, &bbs); 4878 4879 /* Detach ENTRY_BB and EXIT_BB from CFUN->CFG. We need to remember 4880 the predecessor edges to ENTRY_BB and the successor edges to 4881 EXIT_BB so that we can re-attach them to the new basic block that 4882 will replace the region. */ 4883 num_entry_edges = EDGE_COUNT (entry_bb->preds); 4884 entry_pred = (basic_block *) xcalloc (num_entry_edges, sizeof (basic_block)); 4885 entry_flag = (int *) xcalloc (num_entry_edges, sizeof (int)); 4886 i = 0; 4887 for (ei = ei_start (entry_bb->preds); (e = ei_safe_edge (ei)) != NULL;) 4888 { 4889 entry_flag[i] = e->flags; 4890 entry_pred[i++] = e->src; 4891 remove_edge (e); 4892 } 4893 4894 if (exit_bb) 4895 { 4896 num_exit_edges = EDGE_COUNT (exit_bb->succs); 4897 exit_succ = (basic_block *) xcalloc (num_exit_edges, 4898 sizeof (basic_block)); 4899 exit_flag = (int *) xcalloc (num_exit_edges, sizeof (int)); 4900 i = 0; 4901 for (ei = ei_start (exit_bb->succs); (e = ei_safe_edge (ei)) != NULL;) 4902 { 4903 exit_flag[i] = e->flags; 4904 exit_succ[i++] = e->dest; 4905 remove_edge (e); 4906 } 4907 } 4908 else 4909 { 4910 num_exit_edges = 0; 4911 exit_succ = NULL; 4912 exit_flag = NULL; 4913 } 4914 4915 /* Switch context to the child function to initialize DEST_FN's CFG. */ 4916 gcc_assert (dest_cfun->cfg == NULL); 4917 cfun = dest_cfun; 4918 4919 init_empty_tree_cfg (); 4920 4921 /* Initialize EH information for the new function. */ 4922 eh_offset = 0; 4923 new_label_map = NULL; 4924 if (saved_cfun->eh) 4925 { 4926 int region = -1; 4927 4928 for (i = 0; VEC_iterate (basic_block, bbs, i, bb); i++) 4929 region = find_outermost_region_in_block (saved_cfun, bb, region); 4930 4931 init_eh_for_function (); 4932 if (region != -1) 4933 { 4934 new_label_map = htab_create (17, tree_map_hash, tree_map_eq, free); 4935 eh_offset = duplicate_eh_regions (saved_cfun, new_label_mapper, 4936 new_label_map, region, 0); 4937 } 4938 } 4939 4940 cfun = saved_cfun; 4941 4942 /* Move blocks from BBS into DEST_CFUN. */ 4943 gcc_assert (VEC_length (basic_block, bbs) >= 2); 4944 after = dest_cfun->cfg->x_entry_block_ptr; 4945 vars_to_remove = BITMAP_ALLOC (NULL); 4946 for (i = 0; VEC_iterate (basic_block, bbs, i, bb); i++) 4947 { 4948 /* No need to update edge counts on the last block. It has 4949 already been updated earlier when we detached the region from 4950 the original CFG. */ 4951 move_block_to_fn (dest_cfun, bb, after, bb != exit_bb, vars_to_remove, 4952 new_label_map, eh_offset); 4953 after = bb; 4954 } 4955 4956 if (new_label_map) 4957 htab_delete (new_label_map); 4958 4959 /* Remove the variables marked in VARS_TO_REMOVE from 4960 CFUN->UNEXPANDED_VAR_LIST. Otherwise, they will be given a 4961 DECL_RTL in the context of CFUN. */ 4962 if (!bitmap_empty_p (vars_to_remove)) 4963 { 4964 tree *p; 4965 4966 for (p = &cfun->unexpanded_var_list; *p; ) 4967 { 4968 tree var = TREE_VALUE (*p); 4969 if (bitmap_bit_p (vars_to_remove, DECL_UID (var))) 4970 { 4971 *p = TREE_CHAIN (*p); 4972 continue; 4973 } 4974 4975 p = &TREE_CHAIN (*p); 4976 } 4977 } 4978 4979 BITMAP_FREE (vars_to_remove); 4980 4981 /* Rewire the entry and exit blocks. The successor to the entry 4982 block turns into the successor of DEST_FN's ENTRY_BLOCK_PTR in 4983 the child function. Similarly, the predecessor of DEST_FN's 4984 EXIT_BLOCK_PTR turns into the predecessor of EXIT_BLOCK_PTR. We 4985 need to switch CFUN between DEST_CFUN and SAVED_CFUN so that the 4986 various CFG manipulation function get to the right CFG. 4987 4988 FIXME, this is silly. The CFG ought to become a parameter to 4989 these helpers. */ 4990 cfun = dest_cfun; 4991 make_edge (ENTRY_BLOCK_PTR, entry_bb, EDGE_FALLTHRU); 4992 if (exit_bb) 4993 make_edge (exit_bb, EXIT_BLOCK_PTR, 0); 4994 cfun = saved_cfun; 4995 4996 /* Back in the original function, the SESE region has disappeared, 4997 create a new basic block in its place. */ 4998 bb = create_empty_bb (entry_pred[0]); 4999 for (i = 0; i < num_entry_edges; i++) 5000 make_edge (entry_pred[i], bb, entry_flag[i]); 5001 5002 for (i = 0; i < num_exit_edges; i++) 5003 make_edge (bb, exit_succ[i], exit_flag[i]); 5004 5005 if (exit_bb) 5006 { 5007 free (exit_flag); 5008 free (exit_succ); 5009 } 5010 free (entry_flag); 5011 free (entry_pred); 5012 free_dominance_info (CDI_DOMINATORS); 5013 free_dominance_info (CDI_POST_DOMINATORS); 5014 VEC_free (basic_block, heap, bbs); 5015 5016 return bb; 5017} 5018 5019 5020/* Dump FUNCTION_DECL FN to file FILE using FLAGS (see TDF_* in tree.h) */ 5021 5022void 5023dump_function_to_file (tree fn, FILE *file, int flags) 5024{ 5025 tree arg, vars, var; 5026 bool ignore_topmost_bind = false, any_var = false; 5027 basic_block bb; 5028 tree chain; 5029 struct function *saved_cfun; 5030 5031 fprintf (file, "%s (", lang_hooks.decl_printable_name (fn, 2)); 5032 5033 arg = DECL_ARGUMENTS (fn); 5034 while (arg) 5035 { 5036 print_generic_expr (file, arg, dump_flags); 5037 if (TREE_CHAIN (arg)) 5038 fprintf (file, ", "); 5039 arg = TREE_CHAIN (arg); 5040 } 5041 fprintf (file, ")\n"); 5042 5043 if (flags & TDF_DETAILS) 5044 dump_eh_tree (file, DECL_STRUCT_FUNCTION (fn)); 5045 if (flags & TDF_RAW) 5046 { 5047 dump_node (fn, TDF_SLIM | flags, file); 5048 return; 5049 } 5050 5051 /* Switch CFUN to point to FN. */ 5052 saved_cfun = cfun; 5053 cfun = DECL_STRUCT_FUNCTION (fn); 5054 5055 /* When GIMPLE is lowered, the variables are no longer available in 5056 BIND_EXPRs, so display them separately. */ 5057 if (cfun && cfun->decl == fn && cfun->unexpanded_var_list) 5058 { 5059 ignore_topmost_bind = true; 5060 5061 fprintf (file, "{\n"); 5062 for (vars = cfun->unexpanded_var_list; vars; vars = TREE_CHAIN (vars)) 5063 { 5064 var = TREE_VALUE (vars); 5065 5066 print_generic_decl (file, var, flags); 5067 fprintf (file, "\n"); 5068 5069 any_var = true; 5070 } 5071 } 5072 5073 if (cfun && cfun->decl == fn && cfun->cfg && basic_block_info) 5074 { 5075 /* Make a CFG based dump. */ 5076 check_bb_profile (ENTRY_BLOCK_PTR, file); 5077 if (!ignore_topmost_bind) 5078 fprintf (file, "{\n"); 5079 5080 if (any_var && n_basic_blocks) 5081 fprintf (file, "\n"); 5082 5083 FOR_EACH_BB (bb) 5084 dump_generic_bb (file, bb, 2, flags); 5085 5086 fprintf (file, "}\n"); 5087 check_bb_profile (EXIT_BLOCK_PTR, file); 5088 } 5089 else 5090 { 5091 int indent; 5092 5093 /* Make a tree based dump. */ 5094 chain = DECL_SAVED_TREE (fn); 5095 5096 if (chain && TREE_CODE (chain) == BIND_EXPR) 5097 { 5098 if (ignore_topmost_bind) 5099 { 5100 chain = BIND_EXPR_BODY (chain); 5101 indent = 2; 5102 } 5103 else 5104 indent = 0; 5105 } 5106 else 5107 { 5108 if (!ignore_topmost_bind) 5109 fprintf (file, "{\n"); 5110 indent = 2; 5111 } 5112 5113 if (any_var) 5114 fprintf (file, "\n"); 5115 5116 print_generic_stmt_indented (file, chain, flags, indent); 5117 if (ignore_topmost_bind) 5118 fprintf (file, "}\n"); 5119 } 5120 5121 fprintf (file, "\n\n"); 5122 5123 /* Restore CFUN. */ 5124 cfun = saved_cfun; 5125} 5126 5127 5128/* Dump FUNCTION_DECL FN to stderr using FLAGS (see TDF_* in tree.h) */ 5129 5130void 5131debug_function (tree fn, int flags) 5132{ 5133 dump_function_to_file (fn, stderr, flags); 5134} 5135 5136 5137/* Pretty print of the loops intermediate representation. */ 5138static void print_loop (FILE *, struct loop *, int); 5139static void print_pred_bbs (FILE *, basic_block bb); 5140static void print_succ_bbs (FILE *, basic_block bb); 5141 5142 5143/* Print on FILE the indexes for the predecessors of basic_block BB. */ 5144 5145static void 5146print_pred_bbs (FILE *file, basic_block bb) 5147{ 5148 edge e; 5149 edge_iterator ei; 5150 5151 FOR_EACH_EDGE (e, ei, bb->preds) 5152 fprintf (file, "bb_%d ", e->src->index); 5153} 5154 5155 5156/* Print on FILE the indexes for the successors of basic_block BB. */ 5157 5158static void 5159print_succ_bbs (FILE *file, basic_block bb) 5160{ 5161 edge e; 5162 edge_iterator ei; 5163 5164 FOR_EACH_EDGE (e, ei, bb->succs) 5165 fprintf (file, "bb_%d ", e->dest->index); 5166} 5167 5168 5169/* Pretty print LOOP on FILE, indented INDENT spaces. */ 5170 5171static void 5172print_loop (FILE *file, struct loop *loop, int indent) 5173{ 5174 char *s_indent; 5175 basic_block bb; 5176 5177 if (loop == NULL) 5178 return; 5179 5180 s_indent = (char *) alloca ((size_t) indent + 1); 5181 memset ((void *) s_indent, ' ', (size_t) indent); 5182 s_indent[indent] = '\0'; 5183 5184 /* Print the loop's header. */ 5185 fprintf (file, "%sloop_%d\n", s_indent, loop->num); 5186 5187 /* Print the loop's body. */ 5188 fprintf (file, "%s{\n", s_indent); 5189 FOR_EACH_BB (bb) 5190 if (bb->loop_father == loop) 5191 { 5192 /* Print the basic_block's header. */ 5193 fprintf (file, "%s bb_%d (preds = {", s_indent, bb->index); 5194 print_pred_bbs (file, bb); 5195 fprintf (file, "}, succs = {"); 5196 print_succ_bbs (file, bb); 5197 fprintf (file, "})\n"); 5198 5199 /* Print the basic_block's body. */ 5200 fprintf (file, "%s {\n", s_indent); 5201 tree_dump_bb (bb, file, indent + 4); 5202 fprintf (file, "%s }\n", s_indent); 5203 } 5204 5205 print_loop (file, loop->inner, indent + 2); 5206 fprintf (file, "%s}\n", s_indent); 5207 print_loop (file, loop->next, indent); 5208} 5209 5210 5211/* Follow a CFG edge from the entry point of the program, and on entry 5212 of a loop, pretty print the loop structure on FILE. */ 5213 5214void 5215print_loop_ir (FILE *file) 5216{ 5217 basic_block bb; 5218 5219 bb = BASIC_BLOCK (NUM_FIXED_BLOCKS); 5220 if (bb && bb->loop_father) 5221 print_loop (file, bb->loop_father, 0); 5222} 5223 5224 5225/* Debugging loops structure at tree level. */ 5226 5227void 5228debug_loop_ir (void) 5229{ 5230 print_loop_ir (stderr); 5231} 5232 5233 5234/* Return true if BB ends with a call, possibly followed by some 5235 instructions that must stay with the call. Return false, 5236 otherwise. */ 5237 5238static bool 5239tree_block_ends_with_call_p (basic_block bb) 5240{ 5241 block_stmt_iterator bsi = bsi_last (bb); 5242 return get_call_expr_in (bsi_stmt (bsi)) != NULL; 5243} 5244 5245 5246/* Return true if BB ends with a conditional branch. Return false, 5247 otherwise. */ 5248 5249static bool 5250tree_block_ends_with_condjump_p (basic_block bb) 5251{ 5252 tree stmt = last_stmt (bb); 5253 return (stmt && TREE_CODE (stmt) == COND_EXPR); 5254} 5255 5256 5257/* Return true if we need to add fake edge to exit at statement T. 5258 Helper function for tree_flow_call_edges_add. */ 5259 5260static bool 5261need_fake_edge_p (tree t) 5262{ 5263 tree call; 5264 5265 /* NORETURN and LONGJMP calls already have an edge to exit. 5266 CONST and PURE calls do not need one. 5267 We don't currently check for CONST and PURE here, although 5268 it would be a good idea, because those attributes are 5269 figured out from the RTL in mark_constant_function, and 5270 the counter incrementation code from -fprofile-arcs 5271 leads to different results from -fbranch-probabilities. */ 5272 call = get_call_expr_in (t); 5273 if (call 5274 && !(call_expr_flags (call) & ECF_NORETURN)) 5275 return true; 5276 5277 if (TREE_CODE (t) == ASM_EXPR 5278 && (ASM_VOLATILE_P (t) || ASM_INPUT_P (t))) 5279 return true; 5280 5281 return false; 5282} 5283 5284 5285/* Add fake edges to the function exit for any non constant and non 5286 noreturn calls, volatile inline assembly in the bitmap of blocks 5287 specified by BLOCKS or to the whole CFG if BLOCKS is zero. Return 5288 the number of blocks that were split. 5289 5290 The goal is to expose cases in which entering a basic block does 5291 not imply that all subsequent instructions must be executed. */ 5292 5293static int 5294tree_flow_call_edges_add (sbitmap blocks) 5295{ 5296 int i; 5297 int blocks_split = 0; 5298 int last_bb = last_basic_block; 5299 bool check_last_block = false; 5300 5301 if (n_basic_blocks == NUM_FIXED_BLOCKS) 5302 return 0; 5303 5304 if (! blocks) 5305 check_last_block = true; 5306 else 5307 check_last_block = TEST_BIT (blocks, EXIT_BLOCK_PTR->prev_bb->index); 5308 5309 /* In the last basic block, before epilogue generation, there will be 5310 a fallthru edge to EXIT. Special care is required if the last insn 5311 of the last basic block is a call because make_edge folds duplicate 5312 edges, which would result in the fallthru edge also being marked 5313 fake, which would result in the fallthru edge being removed by 5314 remove_fake_edges, which would result in an invalid CFG. 5315 5316 Moreover, we can't elide the outgoing fake edge, since the block 5317 profiler needs to take this into account in order to solve the minimal 5318 spanning tree in the case that the call doesn't return. 5319 5320 Handle this by adding a dummy instruction in a new last basic block. */ 5321 if (check_last_block) 5322 { 5323 basic_block bb = EXIT_BLOCK_PTR->prev_bb; 5324 block_stmt_iterator bsi = bsi_last (bb); 5325 tree t = NULL_TREE; 5326 if (!bsi_end_p (bsi)) 5327 t = bsi_stmt (bsi); 5328 5329 if (t && need_fake_edge_p (t)) 5330 { 5331 edge e; 5332 5333 e = find_edge (bb, EXIT_BLOCK_PTR); 5334 if (e) 5335 { 5336 bsi_insert_on_edge (e, build_empty_stmt ()); 5337 bsi_commit_edge_inserts (); 5338 } 5339 } 5340 } 5341 5342 /* Now add fake edges to the function exit for any non constant 5343 calls since there is no way that we can determine if they will 5344 return or not... */ 5345 for (i = 0; i < last_bb; i++) 5346 { 5347 basic_block bb = BASIC_BLOCK (i); 5348 block_stmt_iterator bsi; 5349 tree stmt, last_stmt; 5350 5351 if (!bb) 5352 continue; 5353 5354 if (blocks && !TEST_BIT (blocks, i)) 5355 continue; 5356 5357 bsi = bsi_last (bb); 5358 if (!bsi_end_p (bsi)) 5359 { 5360 last_stmt = bsi_stmt (bsi); 5361 do 5362 { 5363 stmt = bsi_stmt (bsi); 5364 if (need_fake_edge_p (stmt)) 5365 { 5366 edge e; 5367 /* The handling above of the final block before the 5368 epilogue should be enough to verify that there is 5369 no edge to the exit block in CFG already. 5370 Calling make_edge in such case would cause us to 5371 mark that edge as fake and remove it later. */ 5372#ifdef ENABLE_CHECKING 5373 if (stmt == last_stmt) 5374 { 5375 e = find_edge (bb, EXIT_BLOCK_PTR); 5376 gcc_assert (e == NULL); 5377 } 5378#endif 5379 5380 /* Note that the following may create a new basic block 5381 and renumber the existing basic blocks. */ 5382 if (stmt != last_stmt) 5383 { 5384 e = split_block (bb, stmt); 5385 if (e) 5386 blocks_split++; 5387 } 5388 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE); 5389 } 5390 bsi_prev (&bsi); 5391 } 5392 while (!bsi_end_p (bsi)); 5393 } 5394 } 5395 5396 if (blocks_split) 5397 verify_flow_info (); 5398 5399 return blocks_split; 5400} 5401 5402/* Purge dead abnormal call edges from basic block BB. */ 5403 5404bool 5405tree_purge_dead_abnormal_call_edges (basic_block bb) 5406{ 5407 bool changed = tree_purge_dead_eh_edges (bb); 5408 5409 if (current_function_has_nonlocal_label) 5410 { 5411 tree stmt = last_stmt (bb); 5412 edge_iterator ei; 5413 edge e; 5414 5415 if (!(stmt && tree_can_make_abnormal_goto (stmt))) 5416 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); ) 5417 { 5418 if (e->flags & EDGE_ABNORMAL) 5419 { 5420 remove_edge (e); 5421 changed = true; 5422 } 5423 else 5424 ei_next (&ei); 5425 } 5426 5427 /* See tree_purge_dead_eh_edges below. */ 5428 if (changed) 5429 free_dominance_info (CDI_DOMINATORS); 5430 } 5431 5432 return changed; 5433} 5434 5435/* Purge dead EH edges from basic block BB. */ 5436 5437bool 5438tree_purge_dead_eh_edges (basic_block bb) 5439{ 5440 bool changed = false; 5441 edge e; 5442 edge_iterator ei; 5443 tree stmt = last_stmt (bb); 5444 5445 if (stmt && tree_can_throw_internal (stmt)) 5446 return false; 5447 5448 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); ) 5449 { 5450 if (e->flags & EDGE_EH) 5451 { 5452 remove_edge (e); 5453 changed = true; 5454 } 5455 else 5456 ei_next (&ei); 5457 } 5458 5459 /* Removal of dead EH edges might change dominators of not 5460 just immediate successors. E.g. when bb1 is changed so that 5461 it no longer can throw and bb1->bb3 and bb1->bb4 are dead 5462 eh edges purged by this function in: 5463 0 5464 / \ 5465 v v 5466 1-->2 5467 / \ | 5468 v v | 5469 3-->4 | 5470 \ v 5471 --->5 5472 | 5473 - 5474 idom(bb5) must be recomputed. For now just free the dominance 5475 info. */ 5476 if (changed) 5477 free_dominance_info (CDI_DOMINATORS); 5478 5479 return changed; 5480} 5481 5482bool 5483tree_purge_all_dead_eh_edges (bitmap blocks) 5484{ 5485 bool changed = false; 5486 unsigned i; 5487 bitmap_iterator bi; 5488 5489 EXECUTE_IF_SET_IN_BITMAP (blocks, 0, i, bi) 5490 { 5491 changed |= tree_purge_dead_eh_edges (BASIC_BLOCK (i)); 5492 } 5493 5494 return changed; 5495} 5496 5497/* This function is called whenever a new edge is created or 5498 redirected. */ 5499 5500static void 5501tree_execute_on_growing_pred (edge e) 5502{ 5503 basic_block bb = e->dest; 5504 5505 if (phi_nodes (bb)) 5506 reserve_phi_args_for_new_edge (bb); 5507} 5508 5509/* This function is called immediately before edge E is removed from 5510 the edge vector E->dest->preds. */ 5511 5512static void 5513tree_execute_on_shrinking_pred (edge e) 5514{ 5515 if (phi_nodes (e->dest)) 5516 remove_phi_args (e); 5517} 5518 5519/*--------------------------------------------------------------------------- 5520 Helper functions for Loop versioning 5521 ---------------------------------------------------------------------------*/ 5522 5523/* Adjust phi nodes for 'first' basic block. 'second' basic block is a copy 5524 of 'first'. Both of them are dominated by 'new_head' basic block. When 5525 'new_head' was created by 'second's incoming edge it received phi arguments 5526 on the edge by split_edge(). Later, additional edge 'e' was created to 5527 connect 'new_head' and 'first'. Now this routine adds phi args on this 5528 additional edge 'e' that new_head to second edge received as part of edge 5529 splitting. 5530*/ 5531 5532static void 5533tree_lv_adjust_loop_header_phi (basic_block first, basic_block second, 5534 basic_block new_head, edge e) 5535{ 5536 tree phi1, phi2; 5537 edge e2 = find_edge (new_head, second); 5538 5539 /* Because NEW_HEAD has been created by splitting SECOND's incoming 5540 edge, we should always have an edge from NEW_HEAD to SECOND. */ 5541 gcc_assert (e2 != NULL); 5542 5543 /* Browse all 'second' basic block phi nodes and add phi args to 5544 edge 'e' for 'first' head. PHI args are always in correct order. */ 5545 5546 for (phi2 = phi_nodes (second), phi1 = phi_nodes (first); 5547 phi2 && phi1; 5548 phi2 = PHI_CHAIN (phi2), phi1 = PHI_CHAIN (phi1)) 5549 { 5550 tree def = PHI_ARG_DEF (phi2, e2->dest_idx); 5551 add_phi_arg (phi1, def, e); 5552 } 5553} 5554 5555/* Adds a if else statement to COND_BB with condition COND_EXPR. 5556 SECOND_HEAD is the destination of the THEN and FIRST_HEAD is 5557 the destination of the ELSE part. */ 5558static void 5559tree_lv_add_condition_to_bb (basic_block first_head, basic_block second_head, 5560 basic_block cond_bb, void *cond_e) 5561{ 5562 block_stmt_iterator bsi; 5563 tree goto1 = NULL_TREE; 5564 tree goto2 = NULL_TREE; 5565 tree new_cond_expr = NULL_TREE; 5566 tree cond_expr = (tree) cond_e; 5567 edge e0; 5568 5569 /* Build new conditional expr */ 5570 goto1 = build1 (GOTO_EXPR, void_type_node, tree_block_label (first_head)); 5571 goto2 = build1 (GOTO_EXPR, void_type_node, tree_block_label (second_head)); 5572 new_cond_expr = build3 (COND_EXPR, void_type_node, cond_expr, goto1, goto2); 5573 5574 /* Add new cond in cond_bb. */ 5575 bsi = bsi_start (cond_bb); 5576 bsi_insert_after (&bsi, new_cond_expr, BSI_NEW_STMT); 5577 /* Adjust edges appropriately to connect new head with first head 5578 as well as second head. */ 5579 e0 = single_succ_edge (cond_bb); 5580 e0->flags &= ~EDGE_FALLTHRU; 5581 e0->flags |= EDGE_FALSE_VALUE; 5582} 5583 5584struct cfg_hooks tree_cfg_hooks = { 5585 "tree", 5586 tree_verify_flow_info, 5587 tree_dump_bb, /* dump_bb */ 5588 create_bb, /* create_basic_block */ 5589 tree_redirect_edge_and_branch,/* redirect_edge_and_branch */ 5590 tree_redirect_edge_and_branch_force,/* redirect_edge_and_branch_force */ 5591 remove_bb, /* delete_basic_block */ 5592 tree_split_block, /* split_block */ 5593 tree_move_block_after, /* move_block_after */ 5594 tree_can_merge_blocks_p, /* can_merge_blocks_p */ 5595 tree_merge_blocks, /* merge_blocks */ 5596 tree_predict_edge, /* predict_edge */ 5597 tree_predicted_by_p, /* predicted_by_p */ 5598 tree_can_duplicate_bb_p, /* can_duplicate_block_p */ 5599 tree_duplicate_bb, /* duplicate_block */ 5600 tree_split_edge, /* split_edge */ 5601 tree_make_forwarder_block, /* make_forward_block */ 5602 NULL, /* tidy_fallthru_edge */ 5603 tree_block_ends_with_call_p, /* block_ends_with_call_p */ 5604 tree_block_ends_with_condjump_p, /* block_ends_with_condjump_p */ 5605 tree_flow_call_edges_add, /* flow_call_edges_add */ 5606 tree_execute_on_growing_pred, /* execute_on_growing_pred */ 5607 tree_execute_on_shrinking_pred, /* execute_on_shrinking_pred */ 5608 tree_duplicate_loop_to_header_edge, /* duplicate loop for trees */ 5609 tree_lv_add_condition_to_bb, /* lv_add_condition_to_bb */ 5610 tree_lv_adjust_loop_header_phi, /* lv_adjust_loop_header_phi*/ 5611 extract_true_false_edges_from_block, /* extract_cond_bb_edges */ 5612 flush_pending_stmts /* flush_pending_stmts */ 5613}; 5614 5615 5616/* Split all critical edges. */ 5617 5618static unsigned int 5619split_critical_edges (void) 5620{ 5621 basic_block bb; 5622 edge e; 5623 edge_iterator ei; 5624 5625 /* split_edge can redirect edges out of SWITCH_EXPRs, which can get 5626 expensive. So we want to enable recording of edge to CASE_LABEL_EXPR 5627 mappings around the calls to split_edge. */ 5628 start_recording_case_labels (); 5629 FOR_ALL_BB (bb) 5630 { 5631 FOR_EACH_EDGE (e, ei, bb->succs) 5632 if (EDGE_CRITICAL_P (e) && !(e->flags & EDGE_ABNORMAL)) 5633 { 5634 split_edge (e); 5635 } 5636 } 5637 end_recording_case_labels (); 5638 return 0; 5639} 5640 5641struct tree_opt_pass pass_split_crit_edges = 5642{ 5643 "crited", /* name */ 5644 NULL, /* gate */ 5645 split_critical_edges, /* execute */ 5646 NULL, /* sub */ 5647 NULL, /* next */ 5648 0, /* static_pass_number */ 5649 TV_TREE_SPLIT_EDGES, /* tv_id */ 5650 PROP_cfg, /* properties required */ 5651 PROP_no_crit_edges, /* properties_provided */ 5652 0, /* properties_destroyed */ 5653 0, /* todo_flags_start */ 5654 TODO_dump_func, /* todo_flags_finish */ 5655 0 /* letter */ 5656}; 5657 5658 5659/* Return EXP if it is a valid GIMPLE rvalue, else gimplify it into 5660 a temporary, make sure and register it to be renamed if necessary, 5661 and finally return the temporary. Put the statements to compute 5662 EXP before the current statement in BSI. */ 5663 5664tree 5665gimplify_val (block_stmt_iterator *bsi, tree type, tree exp) 5666{ 5667 tree t, new_stmt, orig_stmt; 5668 5669 if (is_gimple_val (exp)) 5670 return exp; 5671 5672 t = make_rename_temp (type, NULL); 5673 new_stmt = build2 (MODIFY_EXPR, type, t, exp); 5674 5675 orig_stmt = bsi_stmt (*bsi); 5676 SET_EXPR_LOCUS (new_stmt, EXPR_LOCUS (orig_stmt)); 5677 TREE_BLOCK (new_stmt) = TREE_BLOCK (orig_stmt); 5678 5679 bsi_insert_before (bsi, new_stmt, BSI_SAME_STMT); 5680 if (in_ssa_p) 5681 mark_new_vars_to_rename (new_stmt); 5682 5683 return t; 5684} 5685 5686/* Build a ternary operation and gimplify it. Emit code before BSI. 5687 Return the gimple_val holding the result. */ 5688 5689tree 5690gimplify_build3 (block_stmt_iterator *bsi, enum tree_code code, 5691 tree type, tree a, tree b, tree c) 5692{ 5693 tree ret; 5694 5695 ret = fold_build3 (code, type, a, b, c); 5696 STRIP_NOPS (ret); 5697 5698 return gimplify_val (bsi, type, ret); 5699} 5700 5701/* Build a binary operation and gimplify it. Emit code before BSI. 5702 Return the gimple_val holding the result. */ 5703 5704tree 5705gimplify_build2 (block_stmt_iterator *bsi, enum tree_code code, 5706 tree type, tree a, tree b) 5707{ 5708 tree ret; 5709 5710 ret = fold_build2 (code, type, a, b); 5711 STRIP_NOPS (ret); 5712 5713 return gimplify_val (bsi, type, ret); 5714} 5715 5716/* Build a unary operation and gimplify it. Emit code before BSI. 5717 Return the gimple_val holding the result. */ 5718 5719tree 5720gimplify_build1 (block_stmt_iterator *bsi, enum tree_code code, tree type, 5721 tree a) 5722{ 5723 tree ret; 5724 5725 ret = fold_build1 (code, type, a); 5726 STRIP_NOPS (ret); 5727 5728 return gimplify_val (bsi, type, ret); 5729} 5730 5731 5732 5733/* Emit return warnings. */ 5734 5735static unsigned int 5736execute_warn_function_return (void) 5737{ 5738#ifdef USE_MAPPED_LOCATION 5739 source_location location; 5740#else 5741 location_t *locus; 5742#endif 5743 tree last; 5744 edge e; 5745 edge_iterator ei; 5746 5747 /* If we have a path to EXIT, then we do return. */ 5748 if (TREE_THIS_VOLATILE (cfun->decl) 5749 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) > 0) 5750 { 5751#ifdef USE_MAPPED_LOCATION 5752 location = UNKNOWN_LOCATION; 5753#else 5754 locus = NULL; 5755#endif 5756 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds) 5757 { 5758 last = last_stmt (e->src); 5759 if (TREE_CODE (last) == RETURN_EXPR 5760#ifdef USE_MAPPED_LOCATION 5761 && (location = EXPR_LOCATION (last)) != UNKNOWN_LOCATION) 5762#else 5763 && (locus = EXPR_LOCUS (last)) != NULL) 5764#endif 5765 break; 5766 } 5767#ifdef USE_MAPPED_LOCATION 5768 if (location == UNKNOWN_LOCATION) 5769 location = cfun->function_end_locus; 5770 warning (0, "%H%<noreturn%> function does return", &location); 5771#else 5772 if (!locus) 5773 locus = &cfun->function_end_locus; 5774 warning (0, "%H%<noreturn%> function does return", locus); 5775#endif 5776 } 5777 5778 /* If we see "return;" in some basic block, then we do reach the end 5779 without returning a value. */ 5780 else if (warn_return_type 5781 && !TREE_NO_WARNING (cfun->decl) 5782 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) > 0 5783 && !VOID_TYPE_P (TREE_TYPE (TREE_TYPE (cfun->decl)))) 5784 { 5785 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds) 5786 { 5787 tree last = last_stmt (e->src); 5788 if (TREE_CODE (last) == RETURN_EXPR 5789 && TREE_OPERAND (last, 0) == NULL 5790 && !TREE_NO_WARNING (last)) 5791 { 5792#ifdef USE_MAPPED_LOCATION 5793 location = EXPR_LOCATION (last); 5794 if (location == UNKNOWN_LOCATION) 5795 location = cfun->function_end_locus; 5796 warning (0, "%Hcontrol reaches end of non-void function", &location); 5797#else 5798 locus = EXPR_LOCUS (last); 5799 if (!locus) 5800 locus = &cfun->function_end_locus; 5801 warning (0, "%Hcontrol reaches end of non-void function", locus); 5802#endif 5803 TREE_NO_WARNING (cfun->decl) = 1; 5804 break; 5805 } 5806 } 5807 } 5808 return 0; 5809} 5810 5811 5812/* Given a basic block B which ends with a conditional and has 5813 precisely two successors, determine which of the edges is taken if 5814 the conditional is true and which is taken if the conditional is 5815 false. Set TRUE_EDGE and FALSE_EDGE appropriately. */ 5816 5817void 5818extract_true_false_edges_from_block (basic_block b, 5819 edge *true_edge, 5820 edge *false_edge) 5821{ 5822 edge e = EDGE_SUCC (b, 0); 5823 5824 if (e->flags & EDGE_TRUE_VALUE) 5825 { 5826 *true_edge = e; 5827 *false_edge = EDGE_SUCC (b, 1); 5828 } 5829 else 5830 { 5831 *false_edge = e; 5832 *true_edge = EDGE_SUCC (b, 1); 5833 } 5834} 5835 5836struct tree_opt_pass pass_warn_function_return = 5837{ 5838 NULL, /* name */ 5839 NULL, /* gate */ 5840 execute_warn_function_return, /* execute */ 5841 NULL, /* sub */ 5842 NULL, /* next */ 5843 0, /* static_pass_number */ 5844 0, /* tv_id */ 5845 PROP_cfg, /* properties_required */ 5846 0, /* properties_provided */ 5847 0, /* properties_destroyed */ 5848 0, /* todo_flags_start */ 5849 0, /* todo_flags_finish */ 5850 0 /* letter */ 5851}; 5852 5853/* Emit noreturn warnings. */ 5854 5855static unsigned int 5856execute_warn_function_noreturn (void) 5857{ 5858 if (warn_missing_noreturn 5859 && !TREE_THIS_VOLATILE (cfun->decl) 5860 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) == 0 5861 && !lang_hooks.function.missing_noreturn_ok_p (cfun->decl)) 5862 warning (OPT_Wmissing_noreturn, "%Jfunction might be possible candidate " 5863 "for attribute %<noreturn%>", 5864 cfun->decl); 5865 return 0; 5866} 5867 5868struct tree_opt_pass pass_warn_function_noreturn = 5869{ 5870 NULL, /* name */ 5871 NULL, /* gate */ 5872 execute_warn_function_noreturn, /* execute */ 5873 NULL, /* sub */ 5874 NULL, /* next */ 5875 0, /* static_pass_number */ 5876 0, /* tv_id */ 5877 PROP_cfg, /* properties_required */ 5878 0, /* properties_provided */ 5879 0, /* properties_destroyed */ 5880 0, /* todo_flags_start */ 5881 0, /* todo_flags_finish */ 5882 0 /* letter */ 5883}; 5884