tree-eh.c revision 1.6
1/* Exception handling semantics and decomposition for trees. 2 Copyright (C) 2003-2015 Free Software Foundation, Inc. 3 4This file is part of GCC. 5 6GCC is free software; you can redistribute it and/or modify 7it under the terms of the GNU General Public License as published by 8the Free Software Foundation; either version 3, or (at your option) 9any later version. 10 11GCC is distributed in the hope that it will be useful, 12but WITHOUT ANY WARRANTY; without even the implied warranty of 13MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14GNU General Public License for more details. 15 16You should have received a copy of the GNU General Public License 17along with GCC; see the file COPYING3. If not see 18<http://www.gnu.org/licenses/>. */ 19 20#include "config.h" 21#include "system.h" 22#include "coretypes.h" 23#include "hash-table.h" 24#include "tm.h" 25#include "hash-set.h" 26#include "machmode.h" 27#include "vec.h" 28#include "double-int.h" 29#include "input.h" 30#include "alias.h" 31#include "symtab.h" 32#include "wide-int.h" 33#include "inchash.h" 34#include "tree.h" 35#include "fold-const.h" 36#include "hashtab.h" 37#include "hard-reg-set.h" 38#include "function.h" 39#include "rtl.h" 40#include "flags.h" 41#include "statistics.h" 42#include "real.h" 43#include "fixed-value.h" 44#include "insn-config.h" 45#include "expmed.h" 46#include "dojump.h" 47#include "explow.h" 48#include "calls.h" 49#include "emit-rtl.h" 50#include "varasm.h" 51#include "stmt.h" 52#include "expr.h" 53#include "except.h" 54#include "predict.h" 55#include "dominance.h" 56#include "cfg.h" 57#include "cfganal.h" 58#include "cfgcleanup.h" 59#include "basic-block.h" 60#include "tree-ssa-alias.h" 61#include "internal-fn.h" 62#include "tree-eh.h" 63#include "gimple-expr.h" 64#include "is-a.h" 65#include "gimple.h" 66#include "gimple-iterator.h" 67#include "gimple-ssa.h" 68#include "hash-map.h" 69#include "plugin-api.h" 70#include "ipa-ref.h" 71#include "cgraph.h" 72#include "tree-cfg.h" 73#include "tree-phinodes.h" 74#include "ssa-iterators.h" 75#include "stringpool.h" 76#include "tree-ssanames.h" 77#include "tree-into-ssa.h" 78#include "tree-ssa.h" 79#include "tree-inline.h" 80#include "tree-pass.h" 81#include "langhooks.h" 82#include "diagnostic-core.h" 83#include "target.h" 84#include "cfgloop.h" 85#include "gimple-low.h" 86 87/* In some instances a tree and a gimple need to be stored in a same table, 88 i.e. in hash tables. This is a structure to do this. */ 89typedef union {tree *tp; tree t; gimple g;} treemple; 90 91/* Misc functions used in this file. */ 92 93/* Remember and lookup EH landing pad data for arbitrary statements. 94 Really this means any statement that could_throw_p. We could 95 stuff this information into the stmt_ann data structure, but: 96 97 (1) We absolutely rely on this information being kept until 98 we get to rtl. Once we're done with lowering here, if we lose 99 the information there's no way to recover it! 100 101 (2) There are many more statements that *cannot* throw as 102 compared to those that can. We should be saving some amount 103 of space by only allocating memory for those that can throw. */ 104 105/* Add statement T in function IFUN to landing pad NUM. */ 106 107static void 108add_stmt_to_eh_lp_fn (struct function *ifun, gimple t, int num) 109{ 110 gcc_assert (num != 0); 111 112 if (!get_eh_throw_stmt_table (ifun)) 113 set_eh_throw_stmt_table (ifun, hash_map<gimple, int>::create_ggc (31)); 114 115 gcc_assert (!get_eh_throw_stmt_table (ifun)->put (t, num)); 116} 117 118/* Add statement T in the current function (cfun) to EH landing pad NUM. */ 119 120void 121add_stmt_to_eh_lp (gimple t, int num) 122{ 123 add_stmt_to_eh_lp_fn (cfun, t, num); 124} 125 126/* Add statement T to the single EH landing pad in REGION. */ 127 128static void 129record_stmt_eh_region (eh_region region, gimple t) 130{ 131 if (region == NULL) 132 return; 133 if (region->type == ERT_MUST_NOT_THROW) 134 add_stmt_to_eh_lp_fn (cfun, t, -region->index); 135 else 136 { 137 eh_landing_pad lp = region->landing_pads; 138 if (lp == NULL) 139 lp = gen_eh_landing_pad (region); 140 else 141 gcc_assert (lp->next_lp == NULL); 142 add_stmt_to_eh_lp_fn (cfun, t, lp->index); 143 } 144} 145 146 147/* Remove statement T in function IFUN from its EH landing pad. */ 148 149bool 150remove_stmt_from_eh_lp_fn (struct function *ifun, gimple t) 151{ 152 if (!get_eh_throw_stmt_table (ifun)) 153 return false; 154 155 if (!get_eh_throw_stmt_table (ifun)->get (t)) 156 return false; 157 158 get_eh_throw_stmt_table (ifun)->remove (t); 159 return true; 160} 161 162 163/* Remove statement T in the current function (cfun) from its 164 EH landing pad. */ 165 166bool 167remove_stmt_from_eh_lp (gimple t) 168{ 169 return remove_stmt_from_eh_lp_fn (cfun, t); 170} 171 172/* Determine if statement T is inside an EH region in function IFUN. 173 Positive numbers indicate a landing pad index; negative numbers 174 indicate a MUST_NOT_THROW region index; zero indicates that the 175 statement is not recorded in the region table. */ 176 177int 178lookup_stmt_eh_lp_fn (struct function *ifun, gimple t) 179{ 180 if (ifun->eh->throw_stmt_table == NULL) 181 return 0; 182 183 int *lp_nr = ifun->eh->throw_stmt_table->get (t); 184 return lp_nr ? *lp_nr : 0; 185} 186 187/* Likewise, but always use the current function. */ 188 189int 190lookup_stmt_eh_lp (gimple t) 191{ 192 /* We can get called from initialized data when -fnon-call-exceptions 193 is on; prevent crash. */ 194 if (!cfun) 195 return 0; 196 return lookup_stmt_eh_lp_fn (cfun, t); 197} 198 199/* First pass of EH node decomposition. Build up a tree of GIMPLE_TRY_FINALLY 200 nodes and LABEL_DECL nodes. We will use this during the second phase to 201 determine if a goto leaves the body of a TRY_FINALLY_EXPR node. */ 202 203struct finally_tree_node 204{ 205 /* When storing a GIMPLE_TRY, we have to record a gimple. However 206 when deciding whether a GOTO to a certain LABEL_DECL (which is a 207 tree) leaves the TRY block, its necessary to record a tree in 208 this field. Thus a treemple is used. */ 209 treemple child; 210 gtry *parent; 211}; 212 213/* Hashtable helpers. */ 214 215struct finally_tree_hasher : typed_free_remove <finally_tree_node> 216{ 217 typedef finally_tree_node value_type; 218 typedef finally_tree_node compare_type; 219 static inline hashval_t hash (const value_type *); 220 static inline bool equal (const value_type *, const compare_type *); 221}; 222 223inline hashval_t 224finally_tree_hasher::hash (const value_type *v) 225{ 226 return (intptr_t)v->child.t >> 4; 227} 228 229inline bool 230finally_tree_hasher::equal (const value_type *v, const compare_type *c) 231{ 232 return v->child.t == c->child.t; 233} 234 235/* Note that this table is *not* marked GTY. It is short-lived. */ 236static hash_table<finally_tree_hasher> *finally_tree; 237 238static void 239record_in_finally_tree (treemple child, gtry *parent) 240{ 241 struct finally_tree_node *n; 242 finally_tree_node **slot; 243 244 n = XNEW (struct finally_tree_node); 245 n->child = child; 246 n->parent = parent; 247 248 slot = finally_tree->find_slot (n, INSERT); 249 gcc_assert (!*slot); 250 *slot = n; 251} 252 253static void 254collect_finally_tree (gimple stmt, gtry *region); 255 256/* Go through the gimple sequence. Works with collect_finally_tree to 257 record all GIMPLE_LABEL and GIMPLE_TRY statements. */ 258 259static void 260collect_finally_tree_1 (gimple_seq seq, gtry *region) 261{ 262 gimple_stmt_iterator gsi; 263 264 for (gsi = gsi_start (seq); !gsi_end_p (gsi); gsi_next (&gsi)) 265 collect_finally_tree (gsi_stmt (gsi), region); 266} 267 268static void 269collect_finally_tree (gimple stmt, gtry *region) 270{ 271 treemple temp; 272 273 switch (gimple_code (stmt)) 274 { 275 case GIMPLE_LABEL: 276 temp.t = gimple_label_label (as_a <glabel *> (stmt)); 277 record_in_finally_tree (temp, region); 278 break; 279 280 case GIMPLE_TRY: 281 if (gimple_try_kind (stmt) == GIMPLE_TRY_FINALLY) 282 { 283 temp.g = stmt; 284 record_in_finally_tree (temp, region); 285 collect_finally_tree_1 (gimple_try_eval (stmt), 286 as_a <gtry *> (stmt)); 287 collect_finally_tree_1 (gimple_try_cleanup (stmt), region); 288 } 289 else if (gimple_try_kind (stmt) == GIMPLE_TRY_CATCH) 290 { 291 collect_finally_tree_1 (gimple_try_eval (stmt), region); 292 collect_finally_tree_1 (gimple_try_cleanup (stmt), region); 293 } 294 break; 295 296 case GIMPLE_CATCH: 297 collect_finally_tree_1 (gimple_catch_handler ( 298 as_a <gcatch *> (stmt)), 299 region); 300 break; 301 302 case GIMPLE_EH_FILTER: 303 collect_finally_tree_1 (gimple_eh_filter_failure (stmt), region); 304 break; 305 306 case GIMPLE_EH_ELSE: 307 { 308 geh_else *eh_else_stmt = as_a <geh_else *> (stmt); 309 collect_finally_tree_1 (gimple_eh_else_n_body (eh_else_stmt), region); 310 collect_finally_tree_1 (gimple_eh_else_e_body (eh_else_stmt), region); 311 } 312 break; 313 314 default: 315 /* A type, a decl, or some kind of statement that we're not 316 interested in. Don't walk them. */ 317 break; 318 } 319} 320 321 322/* Use the finally tree to determine if a jump from START to TARGET 323 would leave the try_finally node that START lives in. */ 324 325static bool 326outside_finally_tree (treemple start, gimple target) 327{ 328 struct finally_tree_node n, *p; 329 330 do 331 { 332 n.child = start; 333 p = finally_tree->find (&n); 334 if (!p) 335 return true; 336 start.g = p->parent; 337 } 338 while (start.g != target); 339 340 return false; 341} 342 343/* Second pass of EH node decomposition. Actually transform the GIMPLE_TRY 344 nodes into a set of gotos, magic labels, and eh regions. 345 The eh region creation is straight-forward, but frobbing all the gotos 346 and such into shape isn't. */ 347 348/* The sequence into which we record all EH stuff. This will be 349 placed at the end of the function when we're all done. */ 350static gimple_seq eh_seq; 351 352/* Record whether an EH region contains something that can throw, 353 indexed by EH region number. */ 354static bitmap eh_region_may_contain_throw_map; 355 356/* The GOTO_QUEUE is is an array of GIMPLE_GOTO and GIMPLE_RETURN 357 statements that are seen to escape this GIMPLE_TRY_FINALLY node. 358 The idea is to record a gimple statement for everything except for 359 the conditionals, which get their labels recorded. Since labels are 360 of type 'tree', we need this node to store both gimple and tree 361 objects. REPL_STMT is the sequence used to replace the goto/return 362 statement. CONT_STMT is used to store the statement that allows 363 the return/goto to jump to the original destination. */ 364 365struct goto_queue_node 366{ 367 treemple stmt; 368 location_t location; 369 gimple_seq repl_stmt; 370 gimple cont_stmt; 371 int index; 372 /* This is used when index >= 0 to indicate that stmt is a label (as 373 opposed to a goto stmt). */ 374 int is_label; 375}; 376 377/* State of the world while lowering. */ 378 379struct leh_state 380{ 381 /* What's "current" while constructing the eh region tree. These 382 correspond to variables of the same name in cfun->eh, which we 383 don't have easy access to. */ 384 eh_region cur_region; 385 386 /* What's "current" for the purposes of __builtin_eh_pointer. For 387 a CATCH, this is the associated TRY. For an EH_FILTER, this is 388 the associated ALLOWED_EXCEPTIONS, etc. */ 389 eh_region ehp_region; 390 391 /* Processing of TRY_FINALLY requires a bit more state. This is 392 split out into a separate structure so that we don't have to 393 copy so much when processing other nodes. */ 394 struct leh_tf_state *tf; 395}; 396 397struct leh_tf_state 398{ 399 /* Pointer to the GIMPLE_TRY_FINALLY node under discussion. The 400 try_finally_expr is the original GIMPLE_TRY_FINALLY. We need to retain 401 this so that outside_finally_tree can reliably reference the tree used 402 in the collect_finally_tree data structures. */ 403 gtry *try_finally_expr; 404 gtry *top_p; 405 406 /* While lowering a top_p usually it is expanded into multiple statements, 407 thus we need the following field to store them. */ 408 gimple_seq top_p_seq; 409 410 /* The state outside this try_finally node. */ 411 struct leh_state *outer; 412 413 /* The exception region created for it. */ 414 eh_region region; 415 416 /* The goto queue. */ 417 struct goto_queue_node *goto_queue; 418 size_t goto_queue_size; 419 size_t goto_queue_active; 420 421 /* Pointer map to help in searching goto_queue when it is large. */ 422 hash_map<gimple, goto_queue_node *> *goto_queue_map; 423 424 /* The set of unique labels seen as entries in the goto queue. */ 425 vec<tree> dest_array; 426 427 /* A label to be added at the end of the completed transformed 428 sequence. It will be set if may_fallthru was true *at one time*, 429 though subsequent transformations may have cleared that flag. */ 430 tree fallthru_label; 431 432 /* True if it is possible to fall out the bottom of the try block. 433 Cleared if the fallthru is converted to a goto. */ 434 bool may_fallthru; 435 436 /* True if any entry in goto_queue is a GIMPLE_RETURN. */ 437 bool may_return; 438 439 /* True if the finally block can receive an exception edge. 440 Cleared if the exception case is handled by code duplication. */ 441 bool may_throw; 442}; 443 444static gimple_seq lower_eh_must_not_throw (struct leh_state *, gtry *); 445 446/* Search for STMT in the goto queue. Return the replacement, 447 or null if the statement isn't in the queue. */ 448 449#define LARGE_GOTO_QUEUE 20 450 451static void lower_eh_constructs_1 (struct leh_state *state, gimple_seq *seq); 452 453static gimple_seq 454find_goto_replacement (struct leh_tf_state *tf, treemple stmt) 455{ 456 unsigned int i; 457 458 if (tf->goto_queue_active < LARGE_GOTO_QUEUE) 459 { 460 for (i = 0; i < tf->goto_queue_active; i++) 461 if ( tf->goto_queue[i].stmt.g == stmt.g) 462 return tf->goto_queue[i].repl_stmt; 463 return NULL; 464 } 465 466 /* If we have a large number of entries in the goto_queue, create a 467 pointer map and use that for searching. */ 468 469 if (!tf->goto_queue_map) 470 { 471 tf->goto_queue_map = new hash_map<gimple, goto_queue_node *>; 472 for (i = 0; i < tf->goto_queue_active; i++) 473 { 474 bool existed = tf->goto_queue_map->put (tf->goto_queue[i].stmt.g, 475 &tf->goto_queue[i]); 476 gcc_assert (!existed); 477 } 478 } 479 480 goto_queue_node **slot = tf->goto_queue_map->get (stmt.g); 481 if (slot != NULL) 482 return ((*slot)->repl_stmt); 483 484 return NULL; 485} 486 487/* A subroutine of replace_goto_queue_1. Handles the sub-clauses of a 488 lowered GIMPLE_COND. If, by chance, the replacement is a simple goto, 489 then we can just splat it in, otherwise we add the new stmts immediately 490 after the GIMPLE_COND and redirect. */ 491 492static void 493replace_goto_queue_cond_clause (tree *tp, struct leh_tf_state *tf, 494 gimple_stmt_iterator *gsi) 495{ 496 tree label; 497 gimple_seq new_seq; 498 treemple temp; 499 location_t loc = gimple_location (gsi_stmt (*gsi)); 500 501 temp.tp = tp; 502 new_seq = find_goto_replacement (tf, temp); 503 if (!new_seq) 504 return; 505 506 if (gimple_seq_singleton_p (new_seq) 507 && gimple_code (gimple_seq_first_stmt (new_seq)) == GIMPLE_GOTO) 508 { 509 *tp = gimple_goto_dest (gimple_seq_first_stmt (new_seq)); 510 return; 511 } 512 513 label = create_artificial_label (loc); 514 /* Set the new label for the GIMPLE_COND */ 515 *tp = label; 516 517 gsi_insert_after (gsi, gimple_build_label (label), GSI_CONTINUE_LINKING); 518 gsi_insert_seq_after (gsi, gimple_seq_copy (new_seq), GSI_CONTINUE_LINKING); 519} 520 521/* The real work of replace_goto_queue. Returns with TSI updated to 522 point to the next statement. */ 523 524static void replace_goto_queue_stmt_list (gimple_seq *, struct leh_tf_state *); 525 526static void 527replace_goto_queue_1 (gimple stmt, struct leh_tf_state *tf, 528 gimple_stmt_iterator *gsi) 529{ 530 gimple_seq seq; 531 treemple temp; 532 temp.g = NULL; 533 534 switch (gimple_code (stmt)) 535 { 536 case GIMPLE_GOTO: 537 case GIMPLE_RETURN: 538 temp.g = stmt; 539 seq = find_goto_replacement (tf, temp); 540 if (seq) 541 { 542 gsi_insert_seq_before (gsi, gimple_seq_copy (seq), GSI_SAME_STMT); 543 gsi_remove (gsi, false); 544 return; 545 } 546 break; 547 548 case GIMPLE_COND: 549 replace_goto_queue_cond_clause (gimple_op_ptr (stmt, 2), tf, gsi); 550 replace_goto_queue_cond_clause (gimple_op_ptr (stmt, 3), tf, gsi); 551 break; 552 553 case GIMPLE_TRY: 554 replace_goto_queue_stmt_list (gimple_try_eval_ptr (stmt), tf); 555 replace_goto_queue_stmt_list (gimple_try_cleanup_ptr (stmt), tf); 556 break; 557 case GIMPLE_CATCH: 558 replace_goto_queue_stmt_list (gimple_catch_handler_ptr ( 559 as_a <gcatch *> (stmt)), 560 tf); 561 break; 562 case GIMPLE_EH_FILTER: 563 replace_goto_queue_stmt_list (gimple_eh_filter_failure_ptr (stmt), tf); 564 break; 565 case GIMPLE_EH_ELSE: 566 { 567 geh_else *eh_else_stmt = as_a <geh_else *> (stmt); 568 replace_goto_queue_stmt_list (gimple_eh_else_n_body_ptr (eh_else_stmt), 569 tf); 570 replace_goto_queue_stmt_list (gimple_eh_else_e_body_ptr (eh_else_stmt), 571 tf); 572 } 573 break; 574 575 default: 576 /* These won't have gotos in them. */ 577 break; 578 } 579 580 gsi_next (gsi); 581} 582 583/* A subroutine of replace_goto_queue. Handles GIMPLE_SEQ. */ 584 585static void 586replace_goto_queue_stmt_list (gimple_seq *seq, struct leh_tf_state *tf) 587{ 588 gimple_stmt_iterator gsi = gsi_start (*seq); 589 590 while (!gsi_end_p (gsi)) 591 replace_goto_queue_1 (gsi_stmt (gsi), tf, &gsi); 592} 593 594/* Replace all goto queue members. */ 595 596static void 597replace_goto_queue (struct leh_tf_state *tf) 598{ 599 if (tf->goto_queue_active == 0) 600 return; 601 replace_goto_queue_stmt_list (&tf->top_p_seq, tf); 602 replace_goto_queue_stmt_list (&eh_seq, tf); 603} 604 605/* Add a new record to the goto queue contained in TF. NEW_STMT is the 606 data to be added, IS_LABEL indicates whether NEW_STMT is a label or 607 a gimple return. */ 608 609static void 610record_in_goto_queue (struct leh_tf_state *tf, 611 treemple new_stmt, 612 int index, 613 bool is_label, 614 location_t location) 615{ 616 size_t active, size; 617 struct goto_queue_node *q; 618 619 gcc_assert (!tf->goto_queue_map); 620 621 active = tf->goto_queue_active; 622 size = tf->goto_queue_size; 623 if (active >= size) 624 { 625 size = (size ? size * 2 : 32); 626 tf->goto_queue_size = size; 627 tf->goto_queue 628 = XRESIZEVEC (struct goto_queue_node, tf->goto_queue, size); 629 } 630 631 q = &tf->goto_queue[active]; 632 tf->goto_queue_active = active + 1; 633 634 memset (q, 0, sizeof (*q)); 635 q->stmt = new_stmt; 636 q->index = index; 637 q->location = location; 638 q->is_label = is_label; 639} 640 641/* Record the LABEL label in the goto queue contained in TF. 642 TF is not null. */ 643 644static void 645record_in_goto_queue_label (struct leh_tf_state *tf, treemple stmt, tree label, 646 location_t location) 647{ 648 int index; 649 treemple temp, new_stmt; 650 651 if (!label) 652 return; 653 654 /* Computed and non-local gotos do not get processed. Given 655 their nature we can neither tell whether we've escaped the 656 finally block nor redirect them if we knew. */ 657 if (TREE_CODE (label) != LABEL_DECL) 658 return; 659 660 /* No need to record gotos that don't leave the try block. */ 661 temp.t = label; 662 if (!outside_finally_tree (temp, tf->try_finally_expr)) 663 return; 664 665 if (! tf->dest_array.exists ()) 666 { 667 tf->dest_array.create (10); 668 tf->dest_array.quick_push (label); 669 index = 0; 670 } 671 else 672 { 673 int n = tf->dest_array.length (); 674 for (index = 0; index < n; ++index) 675 if (tf->dest_array[index] == label) 676 break; 677 if (index == n) 678 tf->dest_array.safe_push (label); 679 } 680 681 /* In the case of a GOTO we want to record the destination label, 682 since with a GIMPLE_COND we have an easy access to the then/else 683 labels. */ 684 new_stmt = stmt; 685 record_in_goto_queue (tf, new_stmt, index, true, location); 686} 687 688/* For any GIMPLE_GOTO or GIMPLE_RETURN, decide whether it leaves a try_finally 689 node, and if so record that fact in the goto queue associated with that 690 try_finally node. */ 691 692static void 693maybe_record_in_goto_queue (struct leh_state *state, gimple stmt) 694{ 695 struct leh_tf_state *tf = state->tf; 696 treemple new_stmt; 697 698 if (!tf) 699 return; 700 701 switch (gimple_code (stmt)) 702 { 703 case GIMPLE_COND: 704 { 705 gcond *cond_stmt = as_a <gcond *> (stmt); 706 new_stmt.tp = gimple_op_ptr (cond_stmt, 2); 707 record_in_goto_queue_label (tf, new_stmt, 708 gimple_cond_true_label (cond_stmt), 709 EXPR_LOCATION (*new_stmt.tp)); 710 new_stmt.tp = gimple_op_ptr (cond_stmt, 3); 711 record_in_goto_queue_label (tf, new_stmt, 712 gimple_cond_false_label (cond_stmt), 713 EXPR_LOCATION (*new_stmt.tp)); 714 } 715 break; 716 case GIMPLE_GOTO: 717 new_stmt.g = stmt; 718 record_in_goto_queue_label (tf, new_stmt, gimple_goto_dest (stmt), 719 gimple_location (stmt)); 720 break; 721 722 case GIMPLE_RETURN: 723 tf->may_return = true; 724 new_stmt.g = stmt; 725 record_in_goto_queue (tf, new_stmt, -1, false, gimple_location (stmt)); 726 break; 727 728 default: 729 gcc_unreachable (); 730 } 731} 732 733 734#ifdef ENABLE_CHECKING 735/* We do not process GIMPLE_SWITCHes for now. As long as the original source 736 was in fact structured, and we've not yet done jump threading, then none 737 of the labels will leave outer GIMPLE_TRY_FINALLY nodes. Verify this. */ 738 739static void 740verify_norecord_switch_expr (struct leh_state *state, 741 gswitch *switch_expr) 742{ 743 struct leh_tf_state *tf = state->tf; 744 size_t i, n; 745 746 if (!tf) 747 return; 748 749 n = gimple_switch_num_labels (switch_expr); 750 751 for (i = 0; i < n; ++i) 752 { 753 treemple temp; 754 tree lab = CASE_LABEL (gimple_switch_label (switch_expr, i)); 755 temp.t = lab; 756 gcc_assert (!outside_finally_tree (temp, tf->try_finally_expr)); 757 } 758} 759#else 760#define verify_norecord_switch_expr(state, switch_expr) 761#endif 762 763/* Redirect a RETURN_EXPR pointed to by Q to FINLAB. If MOD is 764 non-null, insert it before the new branch. */ 765 766static void 767do_return_redirection (struct goto_queue_node *q, tree finlab, gimple_seq mod) 768{ 769 gimple x; 770 771 /* In the case of a return, the queue node must be a gimple statement. */ 772 gcc_assert (!q->is_label); 773 774 /* Note that the return value may have already been computed, e.g., 775 776 int x; 777 int foo (void) 778 { 779 x = 0; 780 try { 781 return x; 782 } finally { 783 x++; 784 } 785 } 786 787 should return 0, not 1. We don't have to do anything to make 788 this happens because the return value has been placed in the 789 RESULT_DECL already. */ 790 791 q->cont_stmt = q->stmt.g; 792 793 if (mod) 794 gimple_seq_add_seq (&q->repl_stmt, mod); 795 796 x = gimple_build_goto (finlab); 797 gimple_set_location (x, q->location); 798 gimple_seq_add_stmt (&q->repl_stmt, x); 799} 800 801/* Similar, but easier, for GIMPLE_GOTO. */ 802 803static void 804do_goto_redirection (struct goto_queue_node *q, tree finlab, gimple_seq mod, 805 struct leh_tf_state *tf) 806{ 807 ggoto *x; 808 809 gcc_assert (q->is_label); 810 811 q->cont_stmt = gimple_build_goto (tf->dest_array[q->index]); 812 813 if (mod) 814 gimple_seq_add_seq (&q->repl_stmt, mod); 815 816 x = gimple_build_goto (finlab); 817 gimple_set_location (x, q->location); 818 gimple_seq_add_stmt (&q->repl_stmt, x); 819} 820 821/* Emit a standard landing pad sequence into SEQ for REGION. */ 822 823static void 824emit_post_landing_pad (gimple_seq *seq, eh_region region) 825{ 826 eh_landing_pad lp = region->landing_pads; 827 glabel *x; 828 829 if (lp == NULL) 830 lp = gen_eh_landing_pad (region); 831 832 lp->post_landing_pad = create_artificial_label (UNKNOWN_LOCATION); 833 EH_LANDING_PAD_NR (lp->post_landing_pad) = lp->index; 834 835 x = gimple_build_label (lp->post_landing_pad); 836 gimple_seq_add_stmt (seq, x); 837} 838 839/* Emit a RESX statement into SEQ for REGION. */ 840 841static void 842emit_resx (gimple_seq *seq, eh_region region) 843{ 844 gresx *x = gimple_build_resx (region->index); 845 gimple_seq_add_stmt (seq, x); 846 if (region->outer) 847 record_stmt_eh_region (region->outer, x); 848} 849 850/* Emit an EH_DISPATCH statement into SEQ for REGION. */ 851 852static void 853emit_eh_dispatch (gimple_seq *seq, eh_region region) 854{ 855 geh_dispatch *x = gimple_build_eh_dispatch (region->index); 856 gimple_seq_add_stmt (seq, x); 857} 858 859/* Note that the current EH region may contain a throw, or a 860 call to a function which itself may contain a throw. */ 861 862static void 863note_eh_region_may_contain_throw (eh_region region) 864{ 865 while (bitmap_set_bit (eh_region_may_contain_throw_map, region->index)) 866 { 867 if (region->type == ERT_MUST_NOT_THROW) 868 break; 869 region = region->outer; 870 if (region == NULL) 871 break; 872 } 873} 874 875/* Check if REGION has been marked as containing a throw. If REGION is 876 NULL, this predicate is false. */ 877 878static inline bool 879eh_region_may_contain_throw (eh_region r) 880{ 881 return r && bitmap_bit_p (eh_region_may_contain_throw_map, r->index); 882} 883 884/* We want to transform 885 try { body; } catch { stuff; } 886 to 887 normal_sequence: 888 body; 889 over: 890 eh_sequence: 891 landing_pad: 892 stuff; 893 goto over; 894 895 TP is a GIMPLE_TRY node. REGION is the region whose post_landing_pad 896 should be placed before the second operand, or NULL. OVER is 897 an existing label that should be put at the exit, or NULL. */ 898 899static gimple_seq 900frob_into_branch_around (gtry *tp, eh_region region, tree over) 901{ 902 gimple x; 903 gimple_seq cleanup, result; 904 location_t loc = gimple_location (tp); 905 906 cleanup = gimple_try_cleanup (tp); 907 result = gimple_try_eval (tp); 908 909 if (region) 910 emit_post_landing_pad (&eh_seq, region); 911 912 if (gimple_seq_may_fallthru (cleanup)) 913 { 914 if (!over) 915 over = create_artificial_label (loc); 916 x = gimple_build_goto (over); 917 gimple_set_location (x, loc); 918 gimple_seq_add_stmt (&cleanup, x); 919 } 920 gimple_seq_add_seq (&eh_seq, cleanup); 921 922 if (over) 923 { 924 x = gimple_build_label (over); 925 gimple_seq_add_stmt (&result, x); 926 } 927 return result; 928} 929 930/* A subroutine of lower_try_finally. Duplicate the tree rooted at T. 931 Make sure to record all new labels found. */ 932 933static gimple_seq 934lower_try_finally_dup_block (gimple_seq seq, struct leh_state *outer_state, 935 location_t loc) 936{ 937 gtry *region = NULL; 938 gimple_seq new_seq; 939 gimple_stmt_iterator gsi; 940 941 new_seq = copy_gimple_seq_and_replace_locals (seq); 942 943 for (gsi = gsi_start (new_seq); !gsi_end_p (gsi); gsi_next (&gsi)) 944 { 945 gimple stmt = gsi_stmt (gsi); 946 if (LOCATION_LOCUS (gimple_location (stmt)) == UNKNOWN_LOCATION) 947 { 948 tree block = gimple_block (stmt); 949 gimple_set_location (stmt, loc); 950 gimple_set_block (stmt, block); 951 } 952 } 953 954 if (outer_state->tf) 955 region = outer_state->tf->try_finally_expr; 956 collect_finally_tree_1 (new_seq, region); 957 958 return new_seq; 959} 960 961/* A subroutine of lower_try_finally. Create a fallthru label for 962 the given try_finally state. The only tricky bit here is that 963 we have to make sure to record the label in our outer context. */ 964 965static tree 966lower_try_finally_fallthru_label (struct leh_tf_state *tf) 967{ 968 tree label = tf->fallthru_label; 969 treemple temp; 970 971 if (!label) 972 { 973 label = create_artificial_label (gimple_location (tf->try_finally_expr)); 974 tf->fallthru_label = label; 975 if (tf->outer->tf) 976 { 977 temp.t = label; 978 record_in_finally_tree (temp, tf->outer->tf->try_finally_expr); 979 } 980 } 981 return label; 982} 983 984/* A subroutine of lower_try_finally. If FINALLY consits of a 985 GIMPLE_EH_ELSE node, return it. */ 986 987static inline geh_else * 988get_eh_else (gimple_seq finally) 989{ 990 gimple x = gimple_seq_first_stmt (finally); 991 if (gimple_code (x) == GIMPLE_EH_ELSE) 992 { 993 gcc_assert (gimple_seq_singleton_p (finally)); 994 return as_a <geh_else *> (x); 995 } 996 return NULL; 997} 998 999/* A subroutine of lower_try_finally. If the eh_protect_cleanup_actions 1000 langhook returns non-null, then the language requires that the exception 1001 path out of a try_finally be treated specially. To wit: the code within 1002 the finally block may not itself throw an exception. We have two choices 1003 here. First we can duplicate the finally block and wrap it in a 1004 must_not_throw region. Second, we can generate code like 1005 1006 try { 1007 finally_block; 1008 } catch { 1009 if (fintmp == eh_edge) 1010 protect_cleanup_actions; 1011 } 1012 1013 where "fintmp" is the temporary used in the switch statement generation 1014 alternative considered below. For the nonce, we always choose the first 1015 option. 1016 1017 THIS_STATE may be null if this is a try-cleanup, not a try-finally. */ 1018 1019static void 1020honor_protect_cleanup_actions (struct leh_state *outer_state, 1021 struct leh_state *this_state, 1022 struct leh_tf_state *tf) 1023{ 1024 tree protect_cleanup_actions; 1025 gimple_stmt_iterator gsi; 1026 bool finally_may_fallthru; 1027 gimple_seq finally; 1028 gimple x; 1029 geh_mnt *eh_mnt; 1030 gtry *try_stmt; 1031 geh_else *eh_else; 1032 1033 /* First check for nothing to do. */ 1034 if (lang_hooks.eh_protect_cleanup_actions == NULL) 1035 return; 1036 protect_cleanup_actions = lang_hooks.eh_protect_cleanup_actions (); 1037 if (protect_cleanup_actions == NULL) 1038 return; 1039 1040 finally = gimple_try_cleanup (tf->top_p); 1041 eh_else = get_eh_else (finally); 1042 1043 /* Duplicate the FINALLY block. Only need to do this for try-finally, 1044 and not for cleanups. If we've got an EH_ELSE, extract it now. */ 1045 if (eh_else) 1046 { 1047 finally = gimple_eh_else_e_body (eh_else); 1048 gimple_try_set_cleanup (tf->top_p, gimple_eh_else_n_body (eh_else)); 1049 } 1050 else if (this_state) 1051 finally = lower_try_finally_dup_block (finally, outer_state, 1052 gimple_location (tf->try_finally_expr)); 1053 finally_may_fallthru = gimple_seq_may_fallthru (finally); 1054 1055 /* If this cleanup consists of a TRY_CATCH_EXPR with TRY_CATCH_IS_CLEANUP 1056 set, the handler of the TRY_CATCH_EXPR is another cleanup which ought 1057 to be in an enclosing scope, but needs to be implemented at this level 1058 to avoid a nesting violation (see wrap_temporary_cleanups in 1059 cp/decl.c). Since it's logically at an outer level, we should call 1060 terminate before we get to it, so strip it away before adding the 1061 MUST_NOT_THROW filter. */ 1062 gsi = gsi_start (finally); 1063 x = gsi_stmt (gsi); 1064 if (gimple_code (x) == GIMPLE_TRY 1065 && gimple_try_kind (x) == GIMPLE_TRY_CATCH 1066 && gimple_try_catch_is_cleanup (x)) 1067 { 1068 gsi_insert_seq_before (&gsi, gimple_try_eval (x), GSI_SAME_STMT); 1069 gsi_remove (&gsi, false); 1070 } 1071 1072 /* Wrap the block with protect_cleanup_actions as the action. */ 1073 eh_mnt = gimple_build_eh_must_not_throw (protect_cleanup_actions); 1074 try_stmt = gimple_build_try (finally, gimple_seq_alloc_with_stmt (eh_mnt), 1075 GIMPLE_TRY_CATCH); 1076 finally = lower_eh_must_not_throw (outer_state, try_stmt); 1077 1078 /* Drop all of this into the exception sequence. */ 1079 emit_post_landing_pad (&eh_seq, tf->region); 1080 gimple_seq_add_seq (&eh_seq, finally); 1081 if (finally_may_fallthru) 1082 emit_resx (&eh_seq, tf->region); 1083 1084 /* Having now been handled, EH isn't to be considered with 1085 the rest of the outgoing edges. */ 1086 tf->may_throw = false; 1087} 1088 1089/* A subroutine of lower_try_finally. We have determined that there is 1090 no fallthru edge out of the finally block. This means that there is 1091 no outgoing edge corresponding to any incoming edge. Restructure the 1092 try_finally node for this special case. */ 1093 1094static void 1095lower_try_finally_nofallthru (struct leh_state *state, 1096 struct leh_tf_state *tf) 1097{ 1098 tree lab; 1099 gimple x; 1100 geh_else *eh_else; 1101 gimple_seq finally; 1102 struct goto_queue_node *q, *qe; 1103 1104 lab = create_artificial_label (gimple_location (tf->try_finally_expr)); 1105 1106 /* We expect that tf->top_p is a GIMPLE_TRY. */ 1107 finally = gimple_try_cleanup (tf->top_p); 1108 tf->top_p_seq = gimple_try_eval (tf->top_p); 1109 1110 x = gimple_build_label (lab); 1111 gimple_seq_add_stmt (&tf->top_p_seq, x); 1112 1113 q = tf->goto_queue; 1114 qe = q + tf->goto_queue_active; 1115 for (; q < qe; ++q) 1116 if (q->index < 0) 1117 do_return_redirection (q, lab, NULL); 1118 else 1119 do_goto_redirection (q, lab, NULL, tf); 1120 1121 replace_goto_queue (tf); 1122 1123 /* Emit the finally block into the stream. Lower EH_ELSE at this time. */ 1124 eh_else = get_eh_else (finally); 1125 if (eh_else) 1126 { 1127 finally = gimple_eh_else_n_body (eh_else); 1128 lower_eh_constructs_1 (state, &finally); 1129 gimple_seq_add_seq (&tf->top_p_seq, finally); 1130 1131 if (tf->may_throw) 1132 { 1133 finally = gimple_eh_else_e_body (eh_else); 1134 lower_eh_constructs_1 (state, &finally); 1135 1136 emit_post_landing_pad (&eh_seq, tf->region); 1137 gimple_seq_add_seq (&eh_seq, finally); 1138 } 1139 } 1140 else 1141 { 1142 lower_eh_constructs_1 (state, &finally); 1143 gimple_seq_add_seq (&tf->top_p_seq, finally); 1144 1145 if (tf->may_throw) 1146 { 1147 emit_post_landing_pad (&eh_seq, tf->region); 1148 1149 x = gimple_build_goto (lab); 1150 gimple_set_location (x, gimple_location (tf->try_finally_expr)); 1151 gimple_seq_add_stmt (&eh_seq, x); 1152 } 1153 } 1154} 1155 1156/* A subroutine of lower_try_finally. We have determined that there is 1157 exactly one destination of the finally block. Restructure the 1158 try_finally node for this special case. */ 1159 1160static void 1161lower_try_finally_onedest (struct leh_state *state, struct leh_tf_state *tf) 1162{ 1163 struct goto_queue_node *q, *qe; 1164 geh_else *eh_else; 1165 glabel *label_stmt; 1166 gimple x; 1167 gimple_seq finally; 1168 gimple_stmt_iterator gsi; 1169 tree finally_label; 1170 location_t loc = gimple_location (tf->try_finally_expr); 1171 1172 finally = gimple_try_cleanup (tf->top_p); 1173 tf->top_p_seq = gimple_try_eval (tf->top_p); 1174 1175 /* Since there's only one destination, and the destination edge can only 1176 either be EH or non-EH, that implies that all of our incoming edges 1177 are of the same type. Therefore we can lower EH_ELSE immediately. */ 1178 eh_else = get_eh_else (finally); 1179 if (eh_else) 1180 { 1181 if (tf->may_throw) 1182 finally = gimple_eh_else_e_body (eh_else); 1183 else 1184 finally = gimple_eh_else_n_body (eh_else); 1185 } 1186 1187 lower_eh_constructs_1 (state, &finally); 1188 1189 for (gsi = gsi_start (finally); !gsi_end_p (gsi); gsi_next (&gsi)) 1190 { 1191 gimple stmt = gsi_stmt (gsi); 1192 if (LOCATION_LOCUS (gimple_location (stmt)) == UNKNOWN_LOCATION) 1193 { 1194 tree block = gimple_block (stmt); 1195 gimple_set_location (stmt, gimple_location (tf->try_finally_expr)); 1196 gimple_set_block (stmt, block); 1197 } 1198 } 1199 1200 if (tf->may_throw) 1201 { 1202 /* Only reachable via the exception edge. Add the given label to 1203 the head of the FINALLY block. Append a RESX at the end. */ 1204 emit_post_landing_pad (&eh_seq, tf->region); 1205 gimple_seq_add_seq (&eh_seq, finally); 1206 emit_resx (&eh_seq, tf->region); 1207 return; 1208 } 1209 1210 if (tf->may_fallthru) 1211 { 1212 /* Only reachable via the fallthru edge. Do nothing but let 1213 the two blocks run together; we'll fall out the bottom. */ 1214 gimple_seq_add_seq (&tf->top_p_seq, finally); 1215 return; 1216 } 1217 1218 finally_label = create_artificial_label (loc); 1219 label_stmt = gimple_build_label (finally_label); 1220 gimple_seq_add_stmt (&tf->top_p_seq, label_stmt); 1221 1222 gimple_seq_add_seq (&tf->top_p_seq, finally); 1223 1224 q = tf->goto_queue; 1225 qe = q + tf->goto_queue_active; 1226 1227 if (tf->may_return) 1228 { 1229 /* Reachable by return expressions only. Redirect them. */ 1230 for (; q < qe; ++q) 1231 do_return_redirection (q, finally_label, NULL); 1232 replace_goto_queue (tf); 1233 } 1234 else 1235 { 1236 /* Reachable by goto expressions only. Redirect them. */ 1237 for (; q < qe; ++q) 1238 do_goto_redirection (q, finally_label, NULL, tf); 1239 replace_goto_queue (tf); 1240 1241 if (tf->dest_array[0] == tf->fallthru_label) 1242 { 1243 /* Reachable by goto to fallthru label only. Redirect it 1244 to the new label (already created, sadly), and do not 1245 emit the final branch out, or the fallthru label. */ 1246 tf->fallthru_label = NULL; 1247 return; 1248 } 1249 } 1250 1251 /* Place the original return/goto to the original destination 1252 immediately after the finally block. */ 1253 x = tf->goto_queue[0].cont_stmt; 1254 gimple_seq_add_stmt (&tf->top_p_seq, x); 1255 maybe_record_in_goto_queue (state, x); 1256} 1257 1258/* A subroutine of lower_try_finally. There are multiple edges incoming 1259 and outgoing from the finally block. Implement this by duplicating the 1260 finally block for every destination. */ 1261 1262static void 1263lower_try_finally_copy (struct leh_state *state, struct leh_tf_state *tf) 1264{ 1265 gimple_seq finally; 1266 gimple_seq new_stmt; 1267 gimple_seq seq; 1268 gimple x; 1269 geh_else *eh_else; 1270 tree tmp; 1271 location_t tf_loc = gimple_location (tf->try_finally_expr); 1272 1273 finally = gimple_try_cleanup (tf->top_p); 1274 1275 /* Notice EH_ELSE, and simplify some of the remaining code 1276 by considering FINALLY to be the normal return path only. */ 1277 eh_else = get_eh_else (finally); 1278 if (eh_else) 1279 finally = gimple_eh_else_n_body (eh_else); 1280 1281 tf->top_p_seq = gimple_try_eval (tf->top_p); 1282 new_stmt = NULL; 1283 1284 if (tf->may_fallthru) 1285 { 1286 seq = lower_try_finally_dup_block (finally, state, tf_loc); 1287 lower_eh_constructs_1 (state, &seq); 1288 gimple_seq_add_seq (&new_stmt, seq); 1289 1290 tmp = lower_try_finally_fallthru_label (tf); 1291 x = gimple_build_goto (tmp); 1292 gimple_set_location (x, tf_loc); 1293 gimple_seq_add_stmt (&new_stmt, x); 1294 } 1295 1296 if (tf->may_throw) 1297 { 1298 /* We don't need to copy the EH path of EH_ELSE, 1299 since it is only emitted once. */ 1300 if (eh_else) 1301 seq = gimple_eh_else_e_body (eh_else); 1302 else 1303 seq = lower_try_finally_dup_block (finally, state, tf_loc); 1304 lower_eh_constructs_1 (state, &seq); 1305 1306 emit_post_landing_pad (&eh_seq, tf->region); 1307 gimple_seq_add_seq (&eh_seq, seq); 1308 emit_resx (&eh_seq, tf->region); 1309 } 1310 1311 if (tf->goto_queue) 1312 { 1313 struct goto_queue_node *q, *qe; 1314 int return_index, index; 1315 struct labels_s 1316 { 1317 struct goto_queue_node *q; 1318 tree label; 1319 } *labels; 1320 1321 return_index = tf->dest_array.length (); 1322 labels = XCNEWVEC (struct labels_s, return_index + 1); 1323 1324 q = tf->goto_queue; 1325 qe = q + tf->goto_queue_active; 1326 for (; q < qe; q++) 1327 { 1328 index = q->index < 0 ? return_index : q->index; 1329 1330 if (!labels[index].q) 1331 labels[index].q = q; 1332 } 1333 1334 for (index = 0; index < return_index + 1; index++) 1335 { 1336 tree lab; 1337 1338 q = labels[index].q; 1339 if (! q) 1340 continue; 1341 1342 lab = labels[index].label 1343 = create_artificial_label (tf_loc); 1344 1345 if (index == return_index) 1346 do_return_redirection (q, lab, NULL); 1347 else 1348 do_goto_redirection (q, lab, NULL, tf); 1349 1350 x = gimple_build_label (lab); 1351 gimple_seq_add_stmt (&new_stmt, x); 1352 1353 seq = lower_try_finally_dup_block (finally, state, q->location); 1354 lower_eh_constructs_1 (state, &seq); 1355 gimple_seq_add_seq (&new_stmt, seq); 1356 1357 gimple_seq_add_stmt (&new_stmt, q->cont_stmt); 1358 maybe_record_in_goto_queue (state, q->cont_stmt); 1359 } 1360 1361 for (q = tf->goto_queue; q < qe; q++) 1362 { 1363 tree lab; 1364 1365 index = q->index < 0 ? return_index : q->index; 1366 1367 if (labels[index].q == q) 1368 continue; 1369 1370 lab = labels[index].label; 1371 1372 if (index == return_index) 1373 do_return_redirection (q, lab, NULL); 1374 else 1375 do_goto_redirection (q, lab, NULL, tf); 1376 } 1377 1378 replace_goto_queue (tf); 1379 free (labels); 1380 } 1381 1382 /* Need to link new stmts after running replace_goto_queue due 1383 to not wanting to process the same goto stmts twice. */ 1384 gimple_seq_add_seq (&tf->top_p_seq, new_stmt); 1385} 1386 1387/* A subroutine of lower_try_finally. There are multiple edges incoming 1388 and outgoing from the finally block. Implement this by instrumenting 1389 each incoming edge and creating a switch statement at the end of the 1390 finally block that branches to the appropriate destination. */ 1391 1392static void 1393lower_try_finally_switch (struct leh_state *state, struct leh_tf_state *tf) 1394{ 1395 struct goto_queue_node *q, *qe; 1396 tree finally_tmp, finally_label; 1397 int return_index, eh_index, fallthru_index; 1398 int nlabels, ndests, j, last_case_index; 1399 tree last_case; 1400 vec<tree> case_label_vec; 1401 gimple_seq switch_body = NULL; 1402 gimple x; 1403 geh_else *eh_else; 1404 tree tmp; 1405 gimple switch_stmt; 1406 gimple_seq finally; 1407 hash_map<tree, gimple> *cont_map = NULL; 1408 /* The location of the TRY_FINALLY stmt. */ 1409 location_t tf_loc = gimple_location (tf->try_finally_expr); 1410 /* The location of the finally block. */ 1411 location_t finally_loc; 1412 1413 finally = gimple_try_cleanup (tf->top_p); 1414 eh_else = get_eh_else (finally); 1415 1416 /* Mash the TRY block to the head of the chain. */ 1417 tf->top_p_seq = gimple_try_eval (tf->top_p); 1418 1419 /* The location of the finally is either the last stmt in the finally 1420 block or the location of the TRY_FINALLY itself. */ 1421 x = gimple_seq_last_stmt (finally); 1422 finally_loc = x ? gimple_location (x) : tf_loc; 1423 1424 /* Prepare for switch statement generation. */ 1425 nlabels = tf->dest_array.length (); 1426 return_index = nlabels; 1427 eh_index = return_index + tf->may_return; 1428 fallthru_index = eh_index + (tf->may_throw && !eh_else); 1429 ndests = fallthru_index + tf->may_fallthru; 1430 1431 finally_tmp = create_tmp_var (integer_type_node, "finally_tmp"); 1432 finally_label = create_artificial_label (finally_loc); 1433 1434 /* We use vec::quick_push on case_label_vec throughout this function, 1435 since we know the size in advance and allocate precisely as muce 1436 space as needed. */ 1437 case_label_vec.create (ndests); 1438 last_case = NULL; 1439 last_case_index = 0; 1440 1441 /* Begin inserting code for getting to the finally block. Things 1442 are done in this order to correspond to the sequence the code is 1443 laid out. */ 1444 1445 if (tf->may_fallthru) 1446 { 1447 x = gimple_build_assign (finally_tmp, 1448 build_int_cst (integer_type_node, 1449 fallthru_index)); 1450 gimple_seq_add_stmt (&tf->top_p_seq, x); 1451 1452 tmp = build_int_cst (integer_type_node, fallthru_index); 1453 last_case = build_case_label (tmp, NULL, 1454 create_artificial_label (tf_loc)); 1455 case_label_vec.quick_push (last_case); 1456 last_case_index++; 1457 1458 x = gimple_build_label (CASE_LABEL (last_case)); 1459 gimple_seq_add_stmt (&switch_body, x); 1460 1461 tmp = lower_try_finally_fallthru_label (tf); 1462 x = gimple_build_goto (tmp); 1463 gimple_set_location (x, tf_loc); 1464 gimple_seq_add_stmt (&switch_body, x); 1465 } 1466 1467 /* For EH_ELSE, emit the exception path (plus resx) now, then 1468 subsequently we only need consider the normal path. */ 1469 if (eh_else) 1470 { 1471 if (tf->may_throw) 1472 { 1473 finally = gimple_eh_else_e_body (eh_else); 1474 lower_eh_constructs_1 (state, &finally); 1475 1476 emit_post_landing_pad (&eh_seq, tf->region); 1477 gimple_seq_add_seq (&eh_seq, finally); 1478 emit_resx (&eh_seq, tf->region); 1479 } 1480 1481 finally = gimple_eh_else_n_body (eh_else); 1482 } 1483 else if (tf->may_throw) 1484 { 1485 emit_post_landing_pad (&eh_seq, tf->region); 1486 1487 x = gimple_build_assign (finally_tmp, 1488 build_int_cst (integer_type_node, eh_index)); 1489 gimple_seq_add_stmt (&eh_seq, x); 1490 1491 x = gimple_build_goto (finally_label); 1492 gimple_set_location (x, tf_loc); 1493 gimple_seq_add_stmt (&eh_seq, x); 1494 1495 tmp = build_int_cst (integer_type_node, eh_index); 1496 last_case = build_case_label (tmp, NULL, 1497 create_artificial_label (tf_loc)); 1498 case_label_vec.quick_push (last_case); 1499 last_case_index++; 1500 1501 x = gimple_build_label (CASE_LABEL (last_case)); 1502 gimple_seq_add_stmt (&eh_seq, x); 1503 emit_resx (&eh_seq, tf->region); 1504 } 1505 1506 x = gimple_build_label (finally_label); 1507 gimple_seq_add_stmt (&tf->top_p_seq, x); 1508 1509 lower_eh_constructs_1 (state, &finally); 1510 gimple_seq_add_seq (&tf->top_p_seq, finally); 1511 1512 /* Redirect each incoming goto edge. */ 1513 q = tf->goto_queue; 1514 qe = q + tf->goto_queue_active; 1515 j = last_case_index + tf->may_return; 1516 /* Prepare the assignments to finally_tmp that are executed upon the 1517 entrance through a particular edge. */ 1518 for (; q < qe; ++q) 1519 { 1520 gimple_seq mod = NULL; 1521 int switch_id; 1522 unsigned int case_index; 1523 1524 if (q->index < 0) 1525 { 1526 x = gimple_build_assign (finally_tmp, 1527 build_int_cst (integer_type_node, 1528 return_index)); 1529 gimple_seq_add_stmt (&mod, x); 1530 do_return_redirection (q, finally_label, mod); 1531 switch_id = return_index; 1532 } 1533 else 1534 { 1535 x = gimple_build_assign (finally_tmp, 1536 build_int_cst (integer_type_node, q->index)); 1537 gimple_seq_add_stmt (&mod, x); 1538 do_goto_redirection (q, finally_label, mod, tf); 1539 switch_id = q->index; 1540 } 1541 1542 case_index = j + q->index; 1543 if (case_label_vec.length () <= case_index || !case_label_vec[case_index]) 1544 { 1545 tree case_lab; 1546 tmp = build_int_cst (integer_type_node, switch_id); 1547 case_lab = build_case_label (tmp, NULL, 1548 create_artificial_label (tf_loc)); 1549 /* We store the cont_stmt in the pointer map, so that we can recover 1550 it in the loop below. */ 1551 if (!cont_map) 1552 cont_map = new hash_map<tree, gimple>; 1553 cont_map->put (case_lab, q->cont_stmt); 1554 case_label_vec.quick_push (case_lab); 1555 } 1556 } 1557 for (j = last_case_index; j < last_case_index + nlabels; j++) 1558 { 1559 gimple cont_stmt; 1560 1561 last_case = case_label_vec[j]; 1562 1563 gcc_assert (last_case); 1564 gcc_assert (cont_map); 1565 1566 cont_stmt = *cont_map->get (last_case); 1567 1568 x = gimple_build_label (CASE_LABEL (last_case)); 1569 gimple_seq_add_stmt (&switch_body, x); 1570 gimple_seq_add_stmt (&switch_body, cont_stmt); 1571 maybe_record_in_goto_queue (state, cont_stmt); 1572 } 1573 if (cont_map) 1574 delete cont_map; 1575 1576 replace_goto_queue (tf); 1577 1578 /* Make sure that the last case is the default label, as one is required. 1579 Then sort the labels, which is also required in GIMPLE. */ 1580 CASE_LOW (last_case) = NULL; 1581 tree tem = case_label_vec.pop (); 1582 gcc_assert (tem == last_case); 1583 sort_case_labels (case_label_vec); 1584 1585 /* Build the switch statement, setting last_case to be the default 1586 label. */ 1587 switch_stmt = gimple_build_switch (finally_tmp, last_case, 1588 case_label_vec); 1589 gimple_set_location (switch_stmt, finally_loc); 1590 1591 /* Need to link SWITCH_STMT after running replace_goto_queue 1592 due to not wanting to process the same goto stmts twice. */ 1593 gimple_seq_add_stmt (&tf->top_p_seq, switch_stmt); 1594 gimple_seq_add_seq (&tf->top_p_seq, switch_body); 1595} 1596 1597/* Decide whether or not we are going to duplicate the finally block. 1598 There are several considerations. 1599 1600 First, if this is Java, then the finally block contains code 1601 written by the user. It has line numbers associated with it, 1602 so duplicating the block means it's difficult to set a breakpoint. 1603 Since controlling code generation via -g is verboten, we simply 1604 never duplicate code without optimization. 1605 1606 Second, we'd like to prevent egregious code growth. One way to 1607 do this is to estimate the size of the finally block, multiply 1608 that by the number of copies we'd need to make, and compare against 1609 the estimate of the size of the switch machinery we'd have to add. */ 1610 1611static bool 1612decide_copy_try_finally (int ndests, bool may_throw, gimple_seq finally) 1613{ 1614 int f_estimate, sw_estimate; 1615 geh_else *eh_else; 1616 1617 /* If there's an EH_ELSE involved, the exception path is separate 1618 and really doesn't come into play for this computation. */ 1619 eh_else = get_eh_else (finally); 1620 if (eh_else) 1621 { 1622 ndests -= may_throw; 1623 finally = gimple_eh_else_n_body (eh_else); 1624 } 1625 1626 if (!optimize) 1627 { 1628 gimple_stmt_iterator gsi; 1629 1630 if (ndests == 1) 1631 return true; 1632 1633 for (gsi = gsi_start (finally); !gsi_end_p (gsi); gsi_next (&gsi)) 1634 { 1635 gimple stmt = gsi_stmt (gsi); 1636 if (!is_gimple_debug (stmt) && !gimple_clobber_p (stmt)) 1637 return false; 1638 } 1639 return true; 1640 } 1641 1642 /* Finally estimate N times, plus N gotos. */ 1643 f_estimate = count_insns_seq (finally, &eni_size_weights); 1644 f_estimate = (f_estimate + 1) * ndests; 1645 1646 /* Switch statement (cost 10), N variable assignments, N gotos. */ 1647 sw_estimate = 10 + 2 * ndests; 1648 1649 /* Optimize for size clearly wants our best guess. */ 1650 if (optimize_function_for_size_p (cfun)) 1651 return f_estimate < sw_estimate; 1652 1653 /* ??? These numbers are completely made up so far. */ 1654 if (optimize > 1) 1655 return f_estimate < 100 || f_estimate < sw_estimate * 2; 1656 else 1657 return f_estimate < 40 || f_estimate * 2 < sw_estimate * 3; 1658} 1659 1660/* REG is the enclosing region for a possible cleanup region, or the region 1661 itself. Returns TRUE if such a region would be unreachable. 1662 1663 Cleanup regions within a must-not-throw region aren't actually reachable 1664 even if there are throwing stmts within them, because the personality 1665 routine will call terminate before unwinding. */ 1666 1667static bool 1668cleanup_is_dead_in (eh_region reg) 1669{ 1670 while (reg && reg->type == ERT_CLEANUP) 1671 reg = reg->outer; 1672 return (reg && reg->type == ERT_MUST_NOT_THROW); 1673} 1674 1675/* A subroutine of lower_eh_constructs_1. Lower a GIMPLE_TRY_FINALLY nodes 1676 to a sequence of labels and blocks, plus the exception region trees 1677 that record all the magic. This is complicated by the need to 1678 arrange for the FINALLY block to be executed on all exits. */ 1679 1680static gimple_seq 1681lower_try_finally (struct leh_state *state, gtry *tp) 1682{ 1683 struct leh_tf_state this_tf; 1684 struct leh_state this_state; 1685 int ndests; 1686 gimple_seq old_eh_seq; 1687 1688 /* Process the try block. */ 1689 1690 memset (&this_tf, 0, sizeof (this_tf)); 1691 this_tf.try_finally_expr = tp; 1692 this_tf.top_p = tp; 1693 this_tf.outer = state; 1694 if (using_eh_for_cleanups_p () && !cleanup_is_dead_in (state->cur_region)) 1695 { 1696 this_tf.region = gen_eh_region_cleanup (state->cur_region); 1697 this_state.cur_region = this_tf.region; 1698 } 1699 else 1700 { 1701 this_tf.region = NULL; 1702 this_state.cur_region = state->cur_region; 1703 } 1704 1705 this_state.ehp_region = state->ehp_region; 1706 this_state.tf = &this_tf; 1707 1708 old_eh_seq = eh_seq; 1709 eh_seq = NULL; 1710 1711 lower_eh_constructs_1 (&this_state, gimple_try_eval_ptr (tp)); 1712 1713 /* Determine if the try block is escaped through the bottom. */ 1714 this_tf.may_fallthru = gimple_seq_may_fallthru (gimple_try_eval (tp)); 1715 1716 /* Determine if any exceptions are possible within the try block. */ 1717 if (this_tf.region) 1718 this_tf.may_throw = eh_region_may_contain_throw (this_tf.region); 1719 if (this_tf.may_throw) 1720 honor_protect_cleanup_actions (state, &this_state, &this_tf); 1721 1722 /* Determine how many edges (still) reach the finally block. Or rather, 1723 how many destinations are reached by the finally block. Use this to 1724 determine how we process the finally block itself. */ 1725 1726 ndests = this_tf.dest_array.length (); 1727 ndests += this_tf.may_fallthru; 1728 ndests += this_tf.may_return; 1729 ndests += this_tf.may_throw; 1730 1731 /* If the FINALLY block is not reachable, dike it out. */ 1732 if (ndests == 0) 1733 { 1734 gimple_seq_add_seq (&this_tf.top_p_seq, gimple_try_eval (tp)); 1735 gimple_try_set_cleanup (tp, NULL); 1736 } 1737 /* If the finally block doesn't fall through, then any destination 1738 we might try to impose there isn't reached either. There may be 1739 some minor amount of cleanup and redirection still needed. */ 1740 else if (!gimple_seq_may_fallthru (gimple_try_cleanup (tp))) 1741 lower_try_finally_nofallthru (state, &this_tf); 1742 1743 /* We can easily special-case redirection to a single destination. */ 1744 else if (ndests == 1) 1745 lower_try_finally_onedest (state, &this_tf); 1746 else if (decide_copy_try_finally (ndests, this_tf.may_throw, 1747 gimple_try_cleanup (tp))) 1748 lower_try_finally_copy (state, &this_tf); 1749 else 1750 lower_try_finally_switch (state, &this_tf); 1751 1752 /* If someone requested we add a label at the end of the transformed 1753 block, do so. */ 1754 if (this_tf.fallthru_label) 1755 { 1756 /* This must be reached only if ndests == 0. */ 1757 gimple x = gimple_build_label (this_tf.fallthru_label); 1758 gimple_seq_add_stmt (&this_tf.top_p_seq, x); 1759 } 1760 1761 this_tf.dest_array.release (); 1762 free (this_tf.goto_queue); 1763 if (this_tf.goto_queue_map) 1764 delete this_tf.goto_queue_map; 1765 1766 /* If there was an old (aka outer) eh_seq, append the current eh_seq. 1767 If there was no old eh_seq, then the append is trivially already done. */ 1768 if (old_eh_seq) 1769 { 1770 if (eh_seq == NULL) 1771 eh_seq = old_eh_seq; 1772 else 1773 { 1774 gimple_seq new_eh_seq = eh_seq; 1775 eh_seq = old_eh_seq; 1776 gimple_seq_add_seq (&eh_seq, new_eh_seq); 1777 } 1778 } 1779 1780 return this_tf.top_p_seq; 1781} 1782 1783/* A subroutine of lower_eh_constructs_1. Lower a GIMPLE_TRY_CATCH with a 1784 list of GIMPLE_CATCH to a sequence of labels and blocks, plus the 1785 exception region trees that records all the magic. */ 1786 1787static gimple_seq 1788lower_catch (struct leh_state *state, gtry *tp) 1789{ 1790 eh_region try_region = NULL; 1791 struct leh_state this_state = *state; 1792 gimple_stmt_iterator gsi; 1793 tree out_label; 1794 gimple_seq new_seq, cleanup; 1795 gimple x; 1796 location_t try_catch_loc = gimple_location (tp); 1797 1798 if (flag_exceptions) 1799 { 1800 try_region = gen_eh_region_try (state->cur_region); 1801 this_state.cur_region = try_region; 1802 } 1803 1804 lower_eh_constructs_1 (&this_state, gimple_try_eval_ptr (tp)); 1805 1806 if (!eh_region_may_contain_throw (try_region)) 1807 return gimple_try_eval (tp); 1808 1809 new_seq = NULL; 1810 emit_eh_dispatch (&new_seq, try_region); 1811 emit_resx (&new_seq, try_region); 1812 1813 this_state.cur_region = state->cur_region; 1814 this_state.ehp_region = try_region; 1815 1816 /* Add eh_seq from lowering EH in the cleanup sequence after the cleanup 1817 itself, so that e.g. for coverage purposes the nested cleanups don't 1818 appear before the cleanup body. See PR64634 for details. */ 1819 gimple_seq old_eh_seq = eh_seq; 1820 eh_seq = NULL; 1821 1822 out_label = NULL; 1823 cleanup = gimple_try_cleanup (tp); 1824 for (gsi = gsi_start (cleanup); 1825 !gsi_end_p (gsi); 1826 gsi_next (&gsi)) 1827 { 1828 eh_catch c; 1829 gcatch *catch_stmt; 1830 gimple_seq handler; 1831 1832 catch_stmt = as_a <gcatch *> (gsi_stmt (gsi)); 1833 c = gen_eh_region_catch (try_region, gimple_catch_types (catch_stmt)); 1834 1835 handler = gimple_catch_handler (catch_stmt); 1836 lower_eh_constructs_1 (&this_state, &handler); 1837 1838 c->label = create_artificial_label (UNKNOWN_LOCATION); 1839 x = gimple_build_label (c->label); 1840 gimple_seq_add_stmt (&new_seq, x); 1841 1842 gimple_seq_add_seq (&new_seq, handler); 1843 1844 if (gimple_seq_may_fallthru (new_seq)) 1845 { 1846 if (!out_label) 1847 out_label = create_artificial_label (try_catch_loc); 1848 1849 x = gimple_build_goto (out_label); 1850 gimple_seq_add_stmt (&new_seq, x); 1851 } 1852 if (!c->type_list) 1853 break; 1854 } 1855 1856 gimple_try_set_cleanup (tp, new_seq); 1857 1858 gimple_seq new_eh_seq = eh_seq; 1859 eh_seq = old_eh_seq; 1860 gimple_seq ret_seq = frob_into_branch_around (tp, try_region, out_label); 1861 gimple_seq_add_seq (&eh_seq, new_eh_seq); 1862 return ret_seq; 1863} 1864 1865/* A subroutine of lower_eh_constructs_1. Lower a GIMPLE_TRY with a 1866 GIMPLE_EH_FILTER to a sequence of labels and blocks, plus the exception 1867 region trees that record all the magic. */ 1868 1869static gimple_seq 1870lower_eh_filter (struct leh_state *state, gtry *tp) 1871{ 1872 struct leh_state this_state = *state; 1873 eh_region this_region = NULL; 1874 gimple inner, x; 1875 gimple_seq new_seq; 1876 1877 inner = gimple_seq_first_stmt (gimple_try_cleanup (tp)); 1878 1879 if (flag_exceptions) 1880 { 1881 this_region = gen_eh_region_allowed (state->cur_region, 1882 gimple_eh_filter_types (inner)); 1883 this_state.cur_region = this_region; 1884 } 1885 1886 lower_eh_constructs_1 (&this_state, gimple_try_eval_ptr (tp)); 1887 1888 if (!eh_region_may_contain_throw (this_region)) 1889 return gimple_try_eval (tp); 1890 1891 new_seq = NULL; 1892 this_state.cur_region = state->cur_region; 1893 this_state.ehp_region = this_region; 1894 1895 emit_eh_dispatch (&new_seq, this_region); 1896 emit_resx (&new_seq, this_region); 1897 1898 this_region->u.allowed.label = create_artificial_label (UNKNOWN_LOCATION); 1899 x = gimple_build_label (this_region->u.allowed.label); 1900 gimple_seq_add_stmt (&new_seq, x); 1901 1902 lower_eh_constructs_1 (&this_state, gimple_eh_filter_failure_ptr (inner)); 1903 gimple_seq_add_seq (&new_seq, gimple_eh_filter_failure (inner)); 1904 1905 gimple_try_set_cleanup (tp, new_seq); 1906 1907 return frob_into_branch_around (tp, this_region, NULL); 1908} 1909 1910/* A subroutine of lower_eh_constructs_1. Lower a GIMPLE_TRY with 1911 an GIMPLE_EH_MUST_NOT_THROW to a sequence of labels and blocks, 1912 plus the exception region trees that record all the magic. */ 1913 1914static gimple_seq 1915lower_eh_must_not_throw (struct leh_state *state, gtry *tp) 1916{ 1917 struct leh_state this_state = *state; 1918 1919 if (flag_exceptions) 1920 { 1921 gimple inner = gimple_seq_first_stmt (gimple_try_cleanup (tp)); 1922 eh_region this_region; 1923 1924 this_region = gen_eh_region_must_not_throw (state->cur_region); 1925 this_region->u.must_not_throw.failure_decl 1926 = gimple_eh_must_not_throw_fndecl ( 1927 as_a <geh_mnt *> (inner)); 1928 this_region->u.must_not_throw.failure_loc 1929 = LOCATION_LOCUS (gimple_location (tp)); 1930 1931 /* In order to get mangling applied to this decl, we must mark it 1932 used now. Otherwise, pass_ipa_free_lang_data won't think it 1933 needs to happen. */ 1934 TREE_USED (this_region->u.must_not_throw.failure_decl) = 1; 1935 1936 this_state.cur_region = this_region; 1937 } 1938 1939 lower_eh_constructs_1 (&this_state, gimple_try_eval_ptr (tp)); 1940 1941 return gimple_try_eval (tp); 1942} 1943 1944/* Implement a cleanup expression. This is similar to try-finally, 1945 except that we only execute the cleanup block for exception edges. */ 1946 1947static gimple_seq 1948lower_cleanup (struct leh_state *state, gtry *tp) 1949{ 1950 struct leh_state this_state = *state; 1951 eh_region this_region = NULL; 1952 struct leh_tf_state fake_tf; 1953 gimple_seq result; 1954 bool cleanup_dead = cleanup_is_dead_in (state->cur_region); 1955 1956 if (flag_exceptions && !cleanup_dead) 1957 { 1958 this_region = gen_eh_region_cleanup (state->cur_region); 1959 this_state.cur_region = this_region; 1960 } 1961 1962 lower_eh_constructs_1 (&this_state, gimple_try_eval_ptr (tp)); 1963 1964 if (cleanup_dead || !eh_region_may_contain_throw (this_region)) 1965 return gimple_try_eval (tp); 1966 1967 /* Build enough of a try-finally state so that we can reuse 1968 honor_protect_cleanup_actions. */ 1969 memset (&fake_tf, 0, sizeof (fake_tf)); 1970 fake_tf.top_p = fake_tf.try_finally_expr = tp; 1971 fake_tf.outer = state; 1972 fake_tf.region = this_region; 1973 fake_tf.may_fallthru = gimple_seq_may_fallthru (gimple_try_eval (tp)); 1974 fake_tf.may_throw = true; 1975 1976 honor_protect_cleanup_actions (state, NULL, &fake_tf); 1977 1978 if (fake_tf.may_throw) 1979 { 1980 /* In this case honor_protect_cleanup_actions had nothing to do, 1981 and we should process this normally. */ 1982 lower_eh_constructs_1 (state, gimple_try_cleanup_ptr (tp)); 1983 result = frob_into_branch_around (tp, this_region, 1984 fake_tf.fallthru_label); 1985 } 1986 else 1987 { 1988 /* In this case honor_protect_cleanup_actions did nearly all of 1989 the work. All we have left is to append the fallthru_label. */ 1990 1991 result = gimple_try_eval (tp); 1992 if (fake_tf.fallthru_label) 1993 { 1994 gimple x = gimple_build_label (fake_tf.fallthru_label); 1995 gimple_seq_add_stmt (&result, x); 1996 } 1997 } 1998 return result; 1999} 2000 2001/* Main loop for lowering eh constructs. Also moves gsi to the next 2002 statement. */ 2003 2004static void 2005lower_eh_constructs_2 (struct leh_state *state, gimple_stmt_iterator *gsi) 2006{ 2007 gimple_seq replace; 2008 gimple x; 2009 gimple stmt = gsi_stmt (*gsi); 2010 2011 switch (gimple_code (stmt)) 2012 { 2013 case GIMPLE_CALL: 2014 { 2015 tree fndecl = gimple_call_fndecl (stmt); 2016 tree rhs, lhs; 2017 2018 if (fndecl && DECL_BUILT_IN_CLASS (fndecl) == BUILT_IN_NORMAL) 2019 switch (DECL_FUNCTION_CODE (fndecl)) 2020 { 2021 case BUILT_IN_EH_POINTER: 2022 /* The front end may have generated a call to 2023 __builtin_eh_pointer (0) within a catch region. Replace 2024 this zero argument with the current catch region number. */ 2025 if (state->ehp_region) 2026 { 2027 tree nr = build_int_cst (integer_type_node, 2028 state->ehp_region->index); 2029 gimple_call_set_arg (stmt, 0, nr); 2030 } 2031 else 2032 { 2033 /* The user has dome something silly. Remove it. */ 2034 rhs = null_pointer_node; 2035 goto do_replace; 2036 } 2037 break; 2038 2039 case BUILT_IN_EH_FILTER: 2040 /* ??? This should never appear, but since it's a builtin it 2041 is accessible to abuse by users. Just remove it and 2042 replace the use with the arbitrary value zero. */ 2043 rhs = build_int_cst (TREE_TYPE (TREE_TYPE (fndecl)), 0); 2044 do_replace: 2045 lhs = gimple_call_lhs (stmt); 2046 x = gimple_build_assign (lhs, rhs); 2047 gsi_insert_before (gsi, x, GSI_SAME_STMT); 2048 /* FALLTHRU */ 2049 2050 case BUILT_IN_EH_COPY_VALUES: 2051 /* Likewise this should not appear. Remove it. */ 2052 gsi_remove (gsi, true); 2053 return; 2054 2055 default: 2056 break; 2057 } 2058 } 2059 /* FALLTHRU */ 2060 2061 case GIMPLE_ASSIGN: 2062 /* If the stmt can throw use a new temporary for the assignment 2063 to a LHS. This makes sure the old value of the LHS is 2064 available on the EH edge. Only do so for statements that 2065 potentially fall through (no noreturn calls e.g.), otherwise 2066 this new assignment might create fake fallthru regions. */ 2067 if (stmt_could_throw_p (stmt) 2068 && gimple_has_lhs (stmt) 2069 && gimple_stmt_may_fallthru (stmt) 2070 && !tree_could_throw_p (gimple_get_lhs (stmt)) 2071 && is_gimple_reg_type (TREE_TYPE (gimple_get_lhs (stmt)))) 2072 { 2073 tree lhs = gimple_get_lhs (stmt); 2074 tree tmp = create_tmp_var (TREE_TYPE (lhs)); 2075 gimple s = gimple_build_assign (lhs, tmp); 2076 gimple_set_location (s, gimple_location (stmt)); 2077 gimple_set_block (s, gimple_block (stmt)); 2078 gimple_set_lhs (stmt, tmp); 2079 if (TREE_CODE (TREE_TYPE (tmp)) == COMPLEX_TYPE 2080 || TREE_CODE (TREE_TYPE (tmp)) == VECTOR_TYPE) 2081 DECL_GIMPLE_REG_P (tmp) = 1; 2082 gsi_insert_after (gsi, s, GSI_SAME_STMT); 2083 } 2084 /* Look for things that can throw exceptions, and record them. */ 2085 if (state->cur_region && stmt_could_throw_p (stmt)) 2086 { 2087 record_stmt_eh_region (state->cur_region, stmt); 2088 note_eh_region_may_contain_throw (state->cur_region); 2089 } 2090 break; 2091 2092 case GIMPLE_COND: 2093 case GIMPLE_GOTO: 2094 case GIMPLE_RETURN: 2095 maybe_record_in_goto_queue (state, stmt); 2096 break; 2097 2098 case GIMPLE_SWITCH: 2099 verify_norecord_switch_expr (state, as_a <gswitch *> (stmt)); 2100 break; 2101 2102 case GIMPLE_TRY: 2103 { 2104 gtry *try_stmt = as_a <gtry *> (stmt); 2105 if (gimple_try_kind (try_stmt) == GIMPLE_TRY_FINALLY) 2106 replace = lower_try_finally (state, try_stmt); 2107 else 2108 { 2109 x = gimple_seq_first_stmt (gimple_try_cleanup (try_stmt)); 2110 if (!x) 2111 { 2112 replace = gimple_try_eval (try_stmt); 2113 lower_eh_constructs_1 (state, &replace); 2114 } 2115 else 2116 switch (gimple_code (x)) 2117 { 2118 case GIMPLE_CATCH: 2119 replace = lower_catch (state, try_stmt); 2120 break; 2121 case GIMPLE_EH_FILTER: 2122 replace = lower_eh_filter (state, try_stmt); 2123 break; 2124 case GIMPLE_EH_MUST_NOT_THROW: 2125 replace = lower_eh_must_not_throw (state, try_stmt); 2126 break; 2127 case GIMPLE_EH_ELSE: 2128 /* This code is only valid with GIMPLE_TRY_FINALLY. */ 2129 gcc_unreachable (); 2130 default: 2131 replace = lower_cleanup (state, try_stmt); 2132 break; 2133 } 2134 } 2135 } 2136 2137 /* Remove the old stmt and insert the transformed sequence 2138 instead. */ 2139 gsi_insert_seq_before (gsi, replace, GSI_SAME_STMT); 2140 gsi_remove (gsi, true); 2141 2142 /* Return since we don't want gsi_next () */ 2143 return; 2144 2145 case GIMPLE_EH_ELSE: 2146 /* We should be eliminating this in lower_try_finally et al. */ 2147 gcc_unreachable (); 2148 2149 default: 2150 /* A type, a decl, or some kind of statement that we're not 2151 interested in. Don't walk them. */ 2152 break; 2153 } 2154 2155 gsi_next (gsi); 2156} 2157 2158/* A helper to unwrap a gimple_seq and feed stmts to lower_eh_constructs_2. */ 2159 2160static void 2161lower_eh_constructs_1 (struct leh_state *state, gimple_seq *pseq) 2162{ 2163 gimple_stmt_iterator gsi; 2164 for (gsi = gsi_start (*pseq); !gsi_end_p (gsi);) 2165 lower_eh_constructs_2 (state, &gsi); 2166} 2167 2168namespace { 2169 2170const pass_data pass_data_lower_eh = 2171{ 2172 GIMPLE_PASS, /* type */ 2173 "eh", /* name */ 2174 OPTGROUP_NONE, /* optinfo_flags */ 2175 TV_TREE_EH, /* tv_id */ 2176 PROP_gimple_lcf, /* properties_required */ 2177 PROP_gimple_leh, /* properties_provided */ 2178 0, /* properties_destroyed */ 2179 0, /* todo_flags_start */ 2180 0, /* todo_flags_finish */ 2181}; 2182 2183class pass_lower_eh : public gimple_opt_pass 2184{ 2185public: 2186 pass_lower_eh (gcc::context *ctxt) 2187 : gimple_opt_pass (pass_data_lower_eh, ctxt) 2188 {} 2189 2190 /* opt_pass methods: */ 2191 virtual unsigned int execute (function *); 2192 2193}; // class pass_lower_eh 2194 2195unsigned int 2196pass_lower_eh::execute (function *fun) 2197{ 2198 struct leh_state null_state; 2199 gimple_seq bodyp; 2200 2201 bodyp = gimple_body (current_function_decl); 2202 if (bodyp == NULL) 2203 return 0; 2204 2205 finally_tree = new hash_table<finally_tree_hasher> (31); 2206 eh_region_may_contain_throw_map = BITMAP_ALLOC (NULL); 2207 memset (&null_state, 0, sizeof (null_state)); 2208 2209 collect_finally_tree_1 (bodyp, NULL); 2210 lower_eh_constructs_1 (&null_state, &bodyp); 2211 gimple_set_body (current_function_decl, bodyp); 2212 2213 /* We assume there's a return statement, or something, at the end of 2214 the function, and thus ploping the EH sequence afterward won't 2215 change anything. */ 2216 gcc_assert (!gimple_seq_may_fallthru (bodyp)); 2217 gimple_seq_add_seq (&bodyp, eh_seq); 2218 2219 /* We assume that since BODYP already existed, adding EH_SEQ to it 2220 didn't change its value, and we don't have to re-set the function. */ 2221 gcc_assert (bodyp == gimple_body (current_function_decl)); 2222 2223 delete finally_tree; 2224 finally_tree = NULL; 2225 BITMAP_FREE (eh_region_may_contain_throw_map); 2226 eh_seq = NULL; 2227 2228 /* If this function needs a language specific EH personality routine 2229 and the frontend didn't already set one do so now. */ 2230 if (function_needs_eh_personality (fun) == eh_personality_lang 2231 && !DECL_FUNCTION_PERSONALITY (current_function_decl)) 2232 DECL_FUNCTION_PERSONALITY (current_function_decl) 2233 = lang_hooks.eh_personality (); 2234 2235 return 0; 2236} 2237 2238} // anon namespace 2239 2240gimple_opt_pass * 2241make_pass_lower_eh (gcc::context *ctxt) 2242{ 2243 return new pass_lower_eh (ctxt); 2244} 2245 2246/* Create the multiple edges from an EH_DISPATCH statement to all of 2247 the possible handlers for its EH region. Return true if there's 2248 no fallthru edge; false if there is. */ 2249 2250bool 2251make_eh_dispatch_edges (geh_dispatch *stmt) 2252{ 2253 eh_region r; 2254 eh_catch c; 2255 basic_block src, dst; 2256 2257 r = get_eh_region_from_number (gimple_eh_dispatch_region (stmt)); 2258 src = gimple_bb (stmt); 2259 2260 switch (r->type) 2261 { 2262 case ERT_TRY: 2263 for (c = r->u.eh_try.first_catch; c ; c = c->next_catch) 2264 { 2265 dst = label_to_block (c->label); 2266 make_edge (src, dst, 0); 2267 2268 /* A catch-all handler doesn't have a fallthru. */ 2269 if (c->type_list == NULL) 2270 return false; 2271 } 2272 break; 2273 2274 case ERT_ALLOWED_EXCEPTIONS: 2275 dst = label_to_block (r->u.allowed.label); 2276 make_edge (src, dst, 0); 2277 break; 2278 2279 default: 2280 gcc_unreachable (); 2281 } 2282 2283 return true; 2284} 2285 2286/* Create the single EH edge from STMT to its nearest landing pad, 2287 if there is such a landing pad within the current function. */ 2288 2289void 2290make_eh_edges (gimple stmt) 2291{ 2292 basic_block src, dst; 2293 eh_landing_pad lp; 2294 int lp_nr; 2295 2296 lp_nr = lookup_stmt_eh_lp (stmt); 2297 if (lp_nr <= 0) 2298 return; 2299 2300 lp = get_eh_landing_pad_from_number (lp_nr); 2301 gcc_assert (lp != NULL); 2302 2303 src = gimple_bb (stmt); 2304 dst = label_to_block (lp->post_landing_pad); 2305 make_edge (src, dst, EDGE_EH); 2306} 2307 2308/* Do the work in redirecting EDGE_IN to NEW_BB within the EH region tree; 2309 do not actually perform the final edge redirection. 2310 2311 CHANGE_REGION is true when we're being called from cleanup_empty_eh and 2312 we intend to change the destination EH region as well; this means 2313 EH_LANDING_PAD_NR must already be set on the destination block label. 2314 If false, we're being called from generic cfg manipulation code and we 2315 should preserve our place within the region tree. */ 2316 2317static void 2318redirect_eh_edge_1 (edge edge_in, basic_block new_bb, bool change_region) 2319{ 2320 eh_landing_pad old_lp, new_lp; 2321 basic_block old_bb; 2322 gimple throw_stmt; 2323 int old_lp_nr, new_lp_nr; 2324 tree old_label, new_label; 2325 edge_iterator ei; 2326 edge e; 2327 2328 old_bb = edge_in->dest; 2329 old_label = gimple_block_label (old_bb); 2330 old_lp_nr = EH_LANDING_PAD_NR (old_label); 2331 gcc_assert (old_lp_nr > 0); 2332 old_lp = get_eh_landing_pad_from_number (old_lp_nr); 2333 2334 throw_stmt = last_stmt (edge_in->src); 2335 gcc_assert (lookup_stmt_eh_lp (throw_stmt) == old_lp_nr); 2336 2337 new_label = gimple_block_label (new_bb); 2338 2339 /* Look for an existing region that might be using NEW_BB already. */ 2340 new_lp_nr = EH_LANDING_PAD_NR (new_label); 2341 if (new_lp_nr) 2342 { 2343 new_lp = get_eh_landing_pad_from_number (new_lp_nr); 2344 gcc_assert (new_lp); 2345 2346 /* Unless CHANGE_REGION is true, the new and old landing pad 2347 had better be associated with the same EH region. */ 2348 gcc_assert (change_region || new_lp->region == old_lp->region); 2349 } 2350 else 2351 { 2352 new_lp = NULL; 2353 gcc_assert (!change_region); 2354 } 2355 2356 /* Notice when we redirect the last EH edge away from OLD_BB. */ 2357 FOR_EACH_EDGE (e, ei, old_bb->preds) 2358 if (e != edge_in && (e->flags & EDGE_EH)) 2359 break; 2360 2361 if (new_lp) 2362 { 2363 /* NEW_LP already exists. If there are still edges into OLD_LP, 2364 there's nothing to do with the EH tree. If there are no more 2365 edges into OLD_LP, then we want to remove OLD_LP as it is unused. 2366 If CHANGE_REGION is true, then our caller is expecting to remove 2367 the landing pad. */ 2368 if (e == NULL && !change_region) 2369 remove_eh_landing_pad (old_lp); 2370 } 2371 else 2372 { 2373 /* No correct landing pad exists. If there are no more edges 2374 into OLD_LP, then we can simply re-use the existing landing pad. 2375 Otherwise, we have to create a new landing pad. */ 2376 if (e == NULL) 2377 { 2378 EH_LANDING_PAD_NR (old_lp->post_landing_pad) = 0; 2379 new_lp = old_lp; 2380 } 2381 else 2382 new_lp = gen_eh_landing_pad (old_lp->region); 2383 new_lp->post_landing_pad = new_label; 2384 EH_LANDING_PAD_NR (new_label) = new_lp->index; 2385 } 2386 2387 /* Maybe move the throwing statement to the new region. */ 2388 if (old_lp != new_lp) 2389 { 2390 remove_stmt_from_eh_lp (throw_stmt); 2391 add_stmt_to_eh_lp (throw_stmt, new_lp->index); 2392 } 2393} 2394 2395/* Redirect EH edge E to NEW_BB. */ 2396 2397edge 2398redirect_eh_edge (edge edge_in, basic_block new_bb) 2399{ 2400 redirect_eh_edge_1 (edge_in, new_bb, false); 2401 return ssa_redirect_edge (edge_in, new_bb); 2402} 2403 2404/* This is a subroutine of gimple_redirect_edge_and_branch. Update the 2405 labels for redirecting a non-fallthru EH_DISPATCH edge E to NEW_BB. 2406 The actual edge update will happen in the caller. */ 2407 2408void 2409redirect_eh_dispatch_edge (geh_dispatch *stmt, edge e, basic_block new_bb) 2410{ 2411 tree new_lab = gimple_block_label (new_bb); 2412 bool any_changed = false; 2413 basic_block old_bb; 2414 eh_region r; 2415 eh_catch c; 2416 2417 r = get_eh_region_from_number (gimple_eh_dispatch_region (stmt)); 2418 switch (r->type) 2419 { 2420 case ERT_TRY: 2421 for (c = r->u.eh_try.first_catch; c ; c = c->next_catch) 2422 { 2423 old_bb = label_to_block (c->label); 2424 if (old_bb == e->dest) 2425 { 2426 c->label = new_lab; 2427 any_changed = true; 2428 } 2429 } 2430 break; 2431 2432 case ERT_ALLOWED_EXCEPTIONS: 2433 old_bb = label_to_block (r->u.allowed.label); 2434 gcc_assert (old_bb == e->dest); 2435 r->u.allowed.label = new_lab; 2436 any_changed = true; 2437 break; 2438 2439 default: 2440 gcc_unreachable (); 2441 } 2442 2443 gcc_assert (any_changed); 2444} 2445 2446/* Helper function for operation_could_trap_p and stmt_could_throw_p. */ 2447 2448bool 2449operation_could_trap_helper_p (enum tree_code op, 2450 bool fp_operation, 2451 bool honor_trapv, 2452 bool honor_nans, 2453 bool honor_snans, 2454 tree divisor, 2455 bool *handled) 2456{ 2457 *handled = true; 2458 switch (op) 2459 { 2460 case TRUNC_DIV_EXPR: 2461 case CEIL_DIV_EXPR: 2462 case FLOOR_DIV_EXPR: 2463 case ROUND_DIV_EXPR: 2464 case EXACT_DIV_EXPR: 2465 case CEIL_MOD_EXPR: 2466 case FLOOR_MOD_EXPR: 2467 case ROUND_MOD_EXPR: 2468 case TRUNC_MOD_EXPR: 2469 case RDIV_EXPR: 2470 if (honor_snans || honor_trapv) 2471 return true; 2472 if (fp_operation) 2473 return flag_trapping_math; 2474 if (!TREE_CONSTANT (divisor) || integer_zerop (divisor)) 2475 return true; 2476 return false; 2477 2478 case LT_EXPR: 2479 case LE_EXPR: 2480 case GT_EXPR: 2481 case GE_EXPR: 2482 case LTGT_EXPR: 2483 /* Some floating point comparisons may trap. */ 2484 return honor_nans; 2485 2486 case EQ_EXPR: 2487 case NE_EXPR: 2488 case UNORDERED_EXPR: 2489 case ORDERED_EXPR: 2490 case UNLT_EXPR: 2491 case UNLE_EXPR: 2492 case UNGT_EXPR: 2493 case UNGE_EXPR: 2494 case UNEQ_EXPR: 2495 return honor_snans; 2496 2497 case NEGATE_EXPR: 2498 case ABS_EXPR: 2499 case CONJ_EXPR: 2500 /* These operations don't trap with floating point. */ 2501 if (honor_trapv) 2502 return true; 2503 return false; 2504 2505 case PLUS_EXPR: 2506 case MINUS_EXPR: 2507 case MULT_EXPR: 2508 /* Any floating arithmetic may trap. */ 2509 if (fp_operation && flag_trapping_math) 2510 return true; 2511 if (honor_trapv) 2512 return true; 2513 return false; 2514 2515 case COMPLEX_EXPR: 2516 case CONSTRUCTOR: 2517 /* Constructing an object cannot trap. */ 2518 return false; 2519 2520 default: 2521 /* Any floating arithmetic may trap. */ 2522 if (fp_operation && flag_trapping_math) 2523 return true; 2524 2525 *handled = false; 2526 return false; 2527 } 2528} 2529 2530/* Return true if operation OP may trap. FP_OPERATION is true if OP is applied 2531 on floating-point values. HONOR_TRAPV is true if OP is applied on integer 2532 type operands that may trap. If OP is a division operator, DIVISOR contains 2533 the value of the divisor. */ 2534 2535bool 2536operation_could_trap_p (enum tree_code op, bool fp_operation, bool honor_trapv, 2537 tree divisor) 2538{ 2539 bool honor_nans = (fp_operation && flag_trapping_math 2540 && !flag_finite_math_only); 2541 bool honor_snans = fp_operation && flag_signaling_nans != 0; 2542 bool handled; 2543 2544 if (TREE_CODE_CLASS (op) != tcc_comparison 2545 && TREE_CODE_CLASS (op) != tcc_unary 2546 && TREE_CODE_CLASS (op) != tcc_binary 2547 && op != FMA_EXPR) 2548 return false; 2549 2550 return operation_could_trap_helper_p (op, fp_operation, honor_trapv, 2551 honor_nans, honor_snans, divisor, 2552 &handled); 2553} 2554 2555 2556/* Returns true if it is possible to prove that the index of 2557 an array access REF (an ARRAY_REF expression) falls into the 2558 array bounds. */ 2559 2560static bool 2561in_array_bounds_p (tree ref) 2562{ 2563 tree idx = TREE_OPERAND (ref, 1); 2564 tree min, max; 2565 2566 if (TREE_CODE (idx) != INTEGER_CST) 2567 return false; 2568 2569 min = array_ref_low_bound (ref); 2570 max = array_ref_up_bound (ref); 2571 if (!min 2572 || !max 2573 || TREE_CODE (min) != INTEGER_CST 2574 || TREE_CODE (max) != INTEGER_CST) 2575 return false; 2576 2577 if (tree_int_cst_lt (idx, min) 2578 || tree_int_cst_lt (max, idx)) 2579 return false; 2580 2581 return true; 2582} 2583 2584/* Returns true if it is possible to prove that the range of 2585 an array access REF (an ARRAY_RANGE_REF expression) falls 2586 into the array bounds. */ 2587 2588static bool 2589range_in_array_bounds_p (tree ref) 2590{ 2591 tree domain_type = TYPE_DOMAIN (TREE_TYPE (ref)); 2592 tree range_min, range_max, min, max; 2593 2594 range_min = TYPE_MIN_VALUE (domain_type); 2595 range_max = TYPE_MAX_VALUE (domain_type); 2596 if (!range_min 2597 || !range_max 2598 || TREE_CODE (range_min) != INTEGER_CST 2599 || TREE_CODE (range_max) != INTEGER_CST) 2600 return false; 2601 2602 min = array_ref_low_bound (ref); 2603 max = array_ref_up_bound (ref); 2604 if (!min 2605 || !max 2606 || TREE_CODE (min) != INTEGER_CST 2607 || TREE_CODE (max) != INTEGER_CST) 2608 return false; 2609 2610 if (tree_int_cst_lt (range_min, min) 2611 || tree_int_cst_lt (max, range_max)) 2612 return false; 2613 2614 return true; 2615} 2616 2617/* Return true if EXPR can trap, as in dereferencing an invalid pointer 2618 location or floating point arithmetic. C.f. the rtl version, may_trap_p. 2619 This routine expects only GIMPLE lhs or rhs input. */ 2620 2621bool 2622tree_could_trap_p (tree expr) 2623{ 2624 enum tree_code code; 2625 bool fp_operation = false; 2626 bool honor_trapv = false; 2627 tree t, base, div = NULL_TREE; 2628 2629 if (!expr) 2630 return false; 2631 2632 code = TREE_CODE (expr); 2633 t = TREE_TYPE (expr); 2634 2635 if (t) 2636 { 2637 if (COMPARISON_CLASS_P (expr)) 2638 fp_operation = FLOAT_TYPE_P (TREE_TYPE (TREE_OPERAND (expr, 0))); 2639 else 2640 fp_operation = FLOAT_TYPE_P (t); 2641 honor_trapv = INTEGRAL_TYPE_P (t) && TYPE_OVERFLOW_TRAPS (t); 2642 } 2643 2644 if (TREE_CODE_CLASS (code) == tcc_binary) 2645 div = TREE_OPERAND (expr, 1); 2646 if (operation_could_trap_p (code, fp_operation, honor_trapv, div)) 2647 return true; 2648 2649 restart: 2650 switch (code) 2651 { 2652 case COMPONENT_REF: 2653 case REALPART_EXPR: 2654 case IMAGPART_EXPR: 2655 case BIT_FIELD_REF: 2656 case VIEW_CONVERT_EXPR: 2657 case WITH_SIZE_EXPR: 2658 expr = TREE_OPERAND (expr, 0); 2659 code = TREE_CODE (expr); 2660 goto restart; 2661 2662 case ARRAY_RANGE_REF: 2663 base = TREE_OPERAND (expr, 0); 2664 if (tree_could_trap_p (base)) 2665 return true; 2666 if (TREE_THIS_NOTRAP (expr)) 2667 return false; 2668 return !range_in_array_bounds_p (expr); 2669 2670 case ARRAY_REF: 2671 base = TREE_OPERAND (expr, 0); 2672 if (tree_could_trap_p (base)) 2673 return true; 2674 if (TREE_THIS_NOTRAP (expr)) 2675 return false; 2676 return !in_array_bounds_p (expr); 2677 2678 case TARGET_MEM_REF: 2679 case MEM_REF: 2680 if (TREE_CODE (TREE_OPERAND (expr, 0)) == ADDR_EXPR 2681 && tree_could_trap_p (TREE_OPERAND (TREE_OPERAND (expr, 0), 0))) 2682 return true; 2683 if (TREE_THIS_NOTRAP (expr)) 2684 return false; 2685 /* We cannot prove that the access is in-bounds when we have 2686 variable-index TARGET_MEM_REFs. */ 2687 if (code == TARGET_MEM_REF 2688 && (TMR_INDEX (expr) || TMR_INDEX2 (expr))) 2689 return true; 2690 if (TREE_CODE (TREE_OPERAND (expr, 0)) == ADDR_EXPR) 2691 { 2692 tree base = TREE_OPERAND (TREE_OPERAND (expr, 0), 0); 2693 offset_int off = mem_ref_offset (expr); 2694 if (wi::neg_p (off, SIGNED)) 2695 return true; 2696 if (TREE_CODE (base) == STRING_CST) 2697 return wi::leu_p (TREE_STRING_LENGTH (base), off); 2698 else if (DECL_SIZE_UNIT (base) == NULL_TREE 2699 || TREE_CODE (DECL_SIZE_UNIT (base)) != INTEGER_CST 2700 || wi::leu_p (wi::to_offset (DECL_SIZE_UNIT (base)), off)) 2701 return true; 2702 /* Now we are sure the first byte of the access is inside 2703 the object. */ 2704 return false; 2705 } 2706 return true; 2707 2708 case INDIRECT_REF: 2709 return !TREE_THIS_NOTRAP (expr); 2710 2711 case ASM_EXPR: 2712 return TREE_THIS_VOLATILE (expr); 2713 2714 case CALL_EXPR: 2715 t = get_callee_fndecl (expr); 2716 /* Assume that calls to weak functions may trap. */ 2717 if (!t || !DECL_P (t)) 2718 return true; 2719 if (DECL_WEAK (t)) 2720 return tree_could_trap_p (t); 2721 return false; 2722 2723 case FUNCTION_DECL: 2724 /* Assume that accesses to weak functions may trap, unless we know 2725 they are certainly defined in current TU or in some other 2726 LTO partition. */ 2727 if (DECL_WEAK (expr) && !DECL_COMDAT (expr) && DECL_EXTERNAL (expr)) 2728 { 2729 cgraph_node *node = cgraph_node::get (expr); 2730 if (node) 2731 node = node->function_symbol (); 2732 return !(node && node->in_other_partition); 2733 } 2734 return false; 2735 2736 case VAR_DECL: 2737 /* Assume that accesses to weak vars may trap, unless we know 2738 they are certainly defined in current TU or in some other 2739 LTO partition. */ 2740 if (DECL_WEAK (expr) && !DECL_COMDAT (expr) && DECL_EXTERNAL (expr)) 2741 { 2742 varpool_node *node = varpool_node::get (expr); 2743 if (node) 2744 node = node->ultimate_alias_target (); 2745 return !(node && node->in_other_partition); 2746 } 2747 return false; 2748 2749 default: 2750 return false; 2751 } 2752} 2753 2754 2755/* Helper for stmt_could_throw_p. Return true if STMT (assumed to be a 2756 an assignment or a conditional) may throw. */ 2757 2758static bool 2759stmt_could_throw_1_p (gimple stmt) 2760{ 2761 enum tree_code code = gimple_expr_code (stmt); 2762 bool honor_nans = false; 2763 bool honor_snans = false; 2764 bool fp_operation = false; 2765 bool honor_trapv = false; 2766 tree t; 2767 size_t i; 2768 bool handled, ret; 2769 2770 if (TREE_CODE_CLASS (code) == tcc_comparison 2771 || TREE_CODE_CLASS (code) == tcc_unary 2772 || TREE_CODE_CLASS (code) == tcc_binary 2773 || code == FMA_EXPR) 2774 { 2775 if (is_gimple_assign (stmt) 2776 && TREE_CODE_CLASS (code) == tcc_comparison) 2777 t = TREE_TYPE (gimple_assign_rhs1 (stmt)); 2778 else if (gimple_code (stmt) == GIMPLE_COND) 2779 t = TREE_TYPE (gimple_cond_lhs (stmt)); 2780 else 2781 t = gimple_expr_type (stmt); 2782 fp_operation = FLOAT_TYPE_P (t); 2783 if (fp_operation) 2784 { 2785 honor_nans = flag_trapping_math && !flag_finite_math_only; 2786 honor_snans = flag_signaling_nans != 0; 2787 } 2788 else if (INTEGRAL_TYPE_P (t) && TYPE_OVERFLOW_TRAPS (t)) 2789 honor_trapv = true; 2790 } 2791 2792 /* Check if the main expression may trap. */ 2793 t = is_gimple_assign (stmt) ? gimple_assign_rhs2 (stmt) : NULL; 2794 ret = operation_could_trap_helper_p (code, fp_operation, honor_trapv, 2795 honor_nans, honor_snans, t, 2796 &handled); 2797 if (handled) 2798 return ret; 2799 2800 /* If the expression does not trap, see if any of the individual operands may 2801 trap. */ 2802 for (i = 0; i < gimple_num_ops (stmt); i++) 2803 if (tree_could_trap_p (gimple_op (stmt, i))) 2804 return true; 2805 2806 return false; 2807} 2808 2809 2810/* Return true if statement STMT could throw an exception. */ 2811 2812bool 2813stmt_could_throw_p (gimple stmt) 2814{ 2815 if (!flag_exceptions) 2816 return false; 2817 2818 /* The only statements that can throw an exception are assignments, 2819 conditionals, calls, resx, and asms. */ 2820 switch (gimple_code (stmt)) 2821 { 2822 case GIMPLE_RESX: 2823 return true; 2824 2825 case GIMPLE_CALL: 2826 return !gimple_call_nothrow_p (as_a <gcall *> (stmt)); 2827 2828 case GIMPLE_ASSIGN: 2829 case GIMPLE_COND: 2830 if (!cfun->can_throw_non_call_exceptions) 2831 return false; 2832 return stmt_could_throw_1_p (stmt); 2833 2834 case GIMPLE_ASM: 2835 if (!cfun->can_throw_non_call_exceptions) 2836 return false; 2837 return gimple_asm_volatile_p (as_a <gasm *> (stmt)); 2838 2839 default: 2840 return false; 2841 } 2842} 2843 2844 2845/* Return true if expression T could throw an exception. */ 2846 2847bool 2848tree_could_throw_p (tree t) 2849{ 2850 if (!flag_exceptions) 2851 return false; 2852 if (TREE_CODE (t) == MODIFY_EXPR) 2853 { 2854 if (cfun->can_throw_non_call_exceptions 2855 && tree_could_trap_p (TREE_OPERAND (t, 0))) 2856 return true; 2857 t = TREE_OPERAND (t, 1); 2858 } 2859 2860 if (TREE_CODE (t) == WITH_SIZE_EXPR) 2861 t = TREE_OPERAND (t, 0); 2862 if (TREE_CODE (t) == CALL_EXPR) 2863 return (call_expr_flags (t) & ECF_NOTHROW) == 0; 2864 if (cfun->can_throw_non_call_exceptions) 2865 return tree_could_trap_p (t); 2866 return false; 2867} 2868 2869/* Return true if STMT can throw an exception that is not caught within 2870 the current function (CFUN). */ 2871 2872bool 2873stmt_can_throw_external (gimple stmt) 2874{ 2875 int lp_nr; 2876 2877 if (!stmt_could_throw_p (stmt)) 2878 return false; 2879 2880 lp_nr = lookup_stmt_eh_lp (stmt); 2881 return lp_nr == 0; 2882} 2883 2884/* Return true if STMT can throw an exception that is caught within 2885 the current function (CFUN). */ 2886 2887bool 2888stmt_can_throw_internal (gimple stmt) 2889{ 2890 int lp_nr; 2891 2892 if (!stmt_could_throw_p (stmt)) 2893 return false; 2894 2895 lp_nr = lookup_stmt_eh_lp (stmt); 2896 return lp_nr > 0; 2897} 2898 2899/* Given a statement STMT in IFUN, if STMT can no longer throw, then 2900 remove any entry it might have from the EH table. Return true if 2901 any change was made. */ 2902 2903bool 2904maybe_clean_eh_stmt_fn (struct function *ifun, gimple stmt) 2905{ 2906 if (stmt_could_throw_p (stmt)) 2907 return false; 2908 return remove_stmt_from_eh_lp_fn (ifun, stmt); 2909} 2910 2911/* Likewise, but always use the current function. */ 2912 2913bool 2914maybe_clean_eh_stmt (gimple stmt) 2915{ 2916 return maybe_clean_eh_stmt_fn (cfun, stmt); 2917} 2918 2919/* Given a statement OLD_STMT and a new statement NEW_STMT that has replaced 2920 OLD_STMT in the function, remove OLD_STMT from the EH table and put NEW_STMT 2921 in the table if it should be in there. Return TRUE if a replacement was 2922 done that my require an EH edge purge. */ 2923 2924bool 2925maybe_clean_or_replace_eh_stmt (gimple old_stmt, gimple new_stmt) 2926{ 2927 int lp_nr = lookup_stmt_eh_lp (old_stmt); 2928 2929 if (lp_nr != 0) 2930 { 2931 bool new_stmt_could_throw = stmt_could_throw_p (new_stmt); 2932 2933 if (new_stmt == old_stmt && new_stmt_could_throw) 2934 return false; 2935 2936 remove_stmt_from_eh_lp (old_stmt); 2937 if (new_stmt_could_throw) 2938 { 2939 add_stmt_to_eh_lp (new_stmt, lp_nr); 2940 return false; 2941 } 2942 else 2943 return true; 2944 } 2945 2946 return false; 2947} 2948 2949/* Given a statement OLD_STMT in OLD_FUN and a duplicate statement NEW_STMT 2950 in NEW_FUN, copy the EH table data from OLD_STMT to NEW_STMT. The MAP 2951 operand is the return value of duplicate_eh_regions. */ 2952 2953bool 2954maybe_duplicate_eh_stmt_fn (struct function *new_fun, gimple new_stmt, 2955 struct function *old_fun, gimple old_stmt, 2956 hash_map<void *, void *> *map, 2957 int default_lp_nr) 2958{ 2959 int old_lp_nr, new_lp_nr; 2960 2961 if (!stmt_could_throw_p (new_stmt)) 2962 return false; 2963 2964 old_lp_nr = lookup_stmt_eh_lp_fn (old_fun, old_stmt); 2965 if (old_lp_nr == 0) 2966 { 2967 if (default_lp_nr == 0) 2968 return false; 2969 new_lp_nr = default_lp_nr; 2970 } 2971 else if (old_lp_nr > 0) 2972 { 2973 eh_landing_pad old_lp, new_lp; 2974 2975 old_lp = (*old_fun->eh->lp_array)[old_lp_nr]; 2976 new_lp = static_cast<eh_landing_pad> (*map->get (old_lp)); 2977 new_lp_nr = new_lp->index; 2978 } 2979 else 2980 { 2981 eh_region old_r, new_r; 2982 2983 old_r = (*old_fun->eh->region_array)[-old_lp_nr]; 2984 new_r = static_cast<eh_region> (*map->get (old_r)); 2985 new_lp_nr = -new_r->index; 2986 } 2987 2988 add_stmt_to_eh_lp_fn (new_fun, new_stmt, new_lp_nr); 2989 return true; 2990} 2991 2992/* Similar, but both OLD_STMT and NEW_STMT are within the current function, 2993 and thus no remapping is required. */ 2994 2995bool 2996maybe_duplicate_eh_stmt (gimple new_stmt, gimple old_stmt) 2997{ 2998 int lp_nr; 2999 3000 if (!stmt_could_throw_p (new_stmt)) 3001 return false; 3002 3003 lp_nr = lookup_stmt_eh_lp (old_stmt); 3004 if (lp_nr == 0) 3005 return false; 3006 3007 add_stmt_to_eh_lp (new_stmt, lp_nr); 3008 return true; 3009} 3010 3011/* Returns TRUE if oneh and twoh are exception handlers (gimple_try_cleanup of 3012 GIMPLE_TRY) that are similar enough to be considered the same. Currently 3013 this only handles handlers consisting of a single call, as that's the 3014 important case for C++: a destructor call for a particular object showing 3015 up in multiple handlers. */ 3016 3017static bool 3018same_handler_p (gimple_seq oneh, gimple_seq twoh) 3019{ 3020 gimple_stmt_iterator gsi; 3021 gimple ones, twos; 3022 unsigned int ai; 3023 3024 gsi = gsi_start (oneh); 3025 if (!gsi_one_before_end_p (gsi)) 3026 return false; 3027 ones = gsi_stmt (gsi); 3028 3029 gsi = gsi_start (twoh); 3030 if (!gsi_one_before_end_p (gsi)) 3031 return false; 3032 twos = gsi_stmt (gsi); 3033 3034 if (!is_gimple_call (ones) 3035 || !is_gimple_call (twos) 3036 || gimple_call_lhs (ones) 3037 || gimple_call_lhs (twos) 3038 || gimple_call_chain (ones) 3039 || gimple_call_chain (twos) 3040 || !gimple_call_same_target_p (ones, twos) 3041 || gimple_call_num_args (ones) != gimple_call_num_args (twos)) 3042 return false; 3043 3044 for (ai = 0; ai < gimple_call_num_args (ones); ++ai) 3045 if (!operand_equal_p (gimple_call_arg (ones, ai), 3046 gimple_call_arg (twos, ai), 0)) 3047 return false; 3048 3049 return true; 3050} 3051 3052/* Optimize 3053 try { A() } finally { try { ~B() } catch { ~A() } } 3054 try { ... } finally { ~A() } 3055 into 3056 try { A() } catch { ~B() } 3057 try { ~B() ... } finally { ~A() } 3058 3059 This occurs frequently in C++, where A is a local variable and B is a 3060 temporary used in the initializer for A. */ 3061 3062static void 3063optimize_double_finally (gtry *one, gtry *two) 3064{ 3065 gimple oneh; 3066 gimple_stmt_iterator gsi; 3067 gimple_seq cleanup; 3068 3069 cleanup = gimple_try_cleanup (one); 3070 gsi = gsi_start (cleanup); 3071 if (!gsi_one_before_end_p (gsi)) 3072 return; 3073 3074 oneh = gsi_stmt (gsi); 3075 if (gimple_code (oneh) != GIMPLE_TRY 3076 || gimple_try_kind (oneh) != GIMPLE_TRY_CATCH) 3077 return; 3078 3079 if (same_handler_p (gimple_try_cleanup (oneh), gimple_try_cleanup (two))) 3080 { 3081 gimple_seq seq = gimple_try_eval (oneh); 3082 3083 gimple_try_set_cleanup (one, seq); 3084 gimple_try_set_kind (one, GIMPLE_TRY_CATCH); 3085 seq = copy_gimple_seq_and_replace_locals (seq); 3086 gimple_seq_add_seq (&seq, gimple_try_eval (two)); 3087 gimple_try_set_eval (two, seq); 3088 } 3089} 3090 3091/* Perform EH refactoring optimizations that are simpler to do when code 3092 flow has been lowered but EH structures haven't. */ 3093 3094static void 3095refactor_eh_r (gimple_seq seq) 3096{ 3097 gimple_stmt_iterator gsi; 3098 gimple one, two; 3099 3100 one = NULL; 3101 two = NULL; 3102 gsi = gsi_start (seq); 3103 while (1) 3104 { 3105 one = two; 3106 if (gsi_end_p (gsi)) 3107 two = NULL; 3108 else 3109 two = gsi_stmt (gsi); 3110 if (one && two) 3111 if (gtry *try_one = dyn_cast <gtry *> (one)) 3112 if (gtry *try_two = dyn_cast <gtry *> (two)) 3113 if (gimple_try_kind (try_one) == GIMPLE_TRY_FINALLY 3114 && gimple_try_kind (try_two) == GIMPLE_TRY_FINALLY) 3115 optimize_double_finally (try_one, try_two); 3116 if (one) 3117 switch (gimple_code (one)) 3118 { 3119 case GIMPLE_TRY: 3120 refactor_eh_r (gimple_try_eval (one)); 3121 refactor_eh_r (gimple_try_cleanup (one)); 3122 break; 3123 case GIMPLE_CATCH: 3124 refactor_eh_r (gimple_catch_handler (as_a <gcatch *> (one))); 3125 break; 3126 case GIMPLE_EH_FILTER: 3127 refactor_eh_r (gimple_eh_filter_failure (one)); 3128 break; 3129 case GIMPLE_EH_ELSE: 3130 { 3131 geh_else *eh_else_stmt = as_a <geh_else *> (one); 3132 refactor_eh_r (gimple_eh_else_n_body (eh_else_stmt)); 3133 refactor_eh_r (gimple_eh_else_e_body (eh_else_stmt)); 3134 } 3135 break; 3136 default: 3137 break; 3138 } 3139 if (two) 3140 gsi_next (&gsi); 3141 else 3142 break; 3143 } 3144} 3145 3146namespace { 3147 3148const pass_data pass_data_refactor_eh = 3149{ 3150 GIMPLE_PASS, /* type */ 3151 "ehopt", /* name */ 3152 OPTGROUP_NONE, /* optinfo_flags */ 3153 TV_TREE_EH, /* tv_id */ 3154 PROP_gimple_lcf, /* properties_required */ 3155 0, /* properties_provided */ 3156 0, /* properties_destroyed */ 3157 0, /* todo_flags_start */ 3158 0, /* todo_flags_finish */ 3159}; 3160 3161class pass_refactor_eh : public gimple_opt_pass 3162{ 3163public: 3164 pass_refactor_eh (gcc::context *ctxt) 3165 : gimple_opt_pass (pass_data_refactor_eh, ctxt) 3166 {} 3167 3168 /* opt_pass methods: */ 3169 virtual bool gate (function *) { return flag_exceptions != 0; } 3170 virtual unsigned int execute (function *) 3171 { 3172 refactor_eh_r (gimple_body (current_function_decl)); 3173 return 0; 3174 } 3175 3176}; // class pass_refactor_eh 3177 3178} // anon namespace 3179 3180gimple_opt_pass * 3181make_pass_refactor_eh (gcc::context *ctxt) 3182{ 3183 return new pass_refactor_eh (ctxt); 3184} 3185 3186/* At the end of gimple optimization, we can lower RESX. */ 3187 3188static bool 3189lower_resx (basic_block bb, gresx *stmt, 3190 hash_map<eh_region, tree> *mnt_map) 3191{ 3192 int lp_nr; 3193 eh_region src_r, dst_r; 3194 gimple_stmt_iterator gsi; 3195 gimple x; 3196 tree fn, src_nr; 3197 bool ret = false; 3198 3199 lp_nr = lookup_stmt_eh_lp (stmt); 3200 if (lp_nr != 0) 3201 dst_r = get_eh_region_from_lp_number (lp_nr); 3202 else 3203 dst_r = NULL; 3204 3205 src_r = get_eh_region_from_number (gimple_resx_region (stmt)); 3206 gsi = gsi_last_bb (bb); 3207 3208 if (src_r == NULL) 3209 { 3210 /* We can wind up with no source region when pass_cleanup_eh shows 3211 that there are no entries into an eh region and deletes it, but 3212 then the block that contains the resx isn't removed. This can 3213 happen without optimization when the switch statement created by 3214 lower_try_finally_switch isn't simplified to remove the eh case. 3215 3216 Resolve this by expanding the resx node to an abort. */ 3217 3218 fn = builtin_decl_implicit (BUILT_IN_TRAP); 3219 x = gimple_build_call (fn, 0); 3220 gsi_insert_before (&gsi, x, GSI_SAME_STMT); 3221 3222 while (EDGE_COUNT (bb->succs) > 0) 3223 remove_edge (EDGE_SUCC (bb, 0)); 3224 } 3225 else if (dst_r) 3226 { 3227 /* When we have a destination region, we resolve this by copying 3228 the excptr and filter values into place, and changing the edge 3229 to immediately after the landing pad. */ 3230 edge e; 3231 3232 if (lp_nr < 0) 3233 { 3234 basic_block new_bb; 3235 tree lab; 3236 3237 /* We are resuming into a MUST_NOT_CALL region. Expand a call to 3238 the failure decl into a new block, if needed. */ 3239 gcc_assert (dst_r->type == ERT_MUST_NOT_THROW); 3240 3241 tree *slot = mnt_map->get (dst_r); 3242 if (slot == NULL) 3243 { 3244 gimple_stmt_iterator gsi2; 3245 3246 new_bb = create_empty_bb (bb); 3247 add_bb_to_loop (new_bb, bb->loop_father); 3248 lab = gimple_block_label (new_bb); 3249 gsi2 = gsi_start_bb (new_bb); 3250 3251 fn = dst_r->u.must_not_throw.failure_decl; 3252 x = gimple_build_call (fn, 0); 3253 gimple_set_location (x, dst_r->u.must_not_throw.failure_loc); 3254 gsi_insert_after (&gsi2, x, GSI_CONTINUE_LINKING); 3255 3256 mnt_map->put (dst_r, lab); 3257 } 3258 else 3259 { 3260 lab = *slot; 3261 new_bb = label_to_block (lab); 3262 } 3263 3264 gcc_assert (EDGE_COUNT (bb->succs) == 0); 3265 e = make_edge (bb, new_bb, EDGE_FALLTHRU); 3266 e->count = bb->count; 3267 e->probability = REG_BR_PROB_BASE; 3268 } 3269 else 3270 { 3271 edge_iterator ei; 3272 tree dst_nr = build_int_cst (integer_type_node, dst_r->index); 3273 3274 fn = builtin_decl_implicit (BUILT_IN_EH_COPY_VALUES); 3275 src_nr = build_int_cst (integer_type_node, src_r->index); 3276 x = gimple_build_call (fn, 2, dst_nr, src_nr); 3277 gsi_insert_before (&gsi, x, GSI_SAME_STMT); 3278 3279 /* Update the flags for the outgoing edge. */ 3280 e = single_succ_edge (bb); 3281 gcc_assert (e->flags & EDGE_EH); 3282 e->flags = (e->flags & ~EDGE_EH) | EDGE_FALLTHRU; 3283 3284 /* If there are no more EH users of the landing pad, delete it. */ 3285 FOR_EACH_EDGE (e, ei, e->dest->preds) 3286 if (e->flags & EDGE_EH) 3287 break; 3288 if (e == NULL) 3289 { 3290 eh_landing_pad lp = get_eh_landing_pad_from_number (lp_nr); 3291 remove_eh_landing_pad (lp); 3292 } 3293 } 3294 3295 ret = true; 3296 } 3297 else 3298 { 3299 tree var; 3300 3301 /* When we don't have a destination region, this exception escapes 3302 up the call chain. We resolve this by generating a call to the 3303 _Unwind_Resume library function. */ 3304 3305 /* The ARM EABI redefines _Unwind_Resume as __cxa_end_cleanup 3306 with no arguments for C++ and Java. Check for that. */ 3307 if (src_r->use_cxa_end_cleanup) 3308 { 3309 fn = builtin_decl_implicit (BUILT_IN_CXA_END_CLEANUP); 3310 x = gimple_build_call (fn, 0); 3311 gsi_insert_before (&gsi, x, GSI_SAME_STMT); 3312 } 3313 else 3314 { 3315 fn = builtin_decl_implicit (BUILT_IN_EH_POINTER); 3316 src_nr = build_int_cst (integer_type_node, src_r->index); 3317 x = gimple_build_call (fn, 1, src_nr); 3318 var = create_tmp_var (ptr_type_node); 3319 var = make_ssa_name (var, x); 3320 gimple_call_set_lhs (x, var); 3321 gsi_insert_before (&gsi, x, GSI_SAME_STMT); 3322 3323 fn = builtin_decl_implicit (BUILT_IN_UNWIND_RESUME); 3324 x = gimple_build_call (fn, 1, var); 3325 gsi_insert_before (&gsi, x, GSI_SAME_STMT); 3326 } 3327 3328 gcc_assert (EDGE_COUNT (bb->succs) == 0); 3329 } 3330 3331 gsi_remove (&gsi, true); 3332 3333 return ret; 3334} 3335 3336namespace { 3337 3338const pass_data pass_data_lower_resx = 3339{ 3340 GIMPLE_PASS, /* type */ 3341 "resx", /* name */ 3342 OPTGROUP_NONE, /* optinfo_flags */ 3343 TV_TREE_EH, /* tv_id */ 3344 PROP_gimple_lcf, /* properties_required */ 3345 0, /* properties_provided */ 3346 0, /* properties_destroyed */ 3347 0, /* todo_flags_start */ 3348 0, /* todo_flags_finish */ 3349}; 3350 3351class pass_lower_resx : public gimple_opt_pass 3352{ 3353public: 3354 pass_lower_resx (gcc::context *ctxt) 3355 : gimple_opt_pass (pass_data_lower_resx, ctxt) 3356 {} 3357 3358 /* opt_pass methods: */ 3359 virtual bool gate (function *) { return flag_exceptions != 0; } 3360 virtual unsigned int execute (function *); 3361 3362}; // class pass_lower_resx 3363 3364unsigned 3365pass_lower_resx::execute (function *fun) 3366{ 3367 basic_block bb; 3368 bool dominance_invalidated = false; 3369 bool any_rewritten = false; 3370 3371 hash_map<eh_region, tree> mnt_map; 3372 3373 FOR_EACH_BB_FN (bb, fun) 3374 { 3375 gimple last = last_stmt (bb); 3376 if (last && is_gimple_resx (last)) 3377 { 3378 dominance_invalidated |= 3379 lower_resx (bb, as_a <gresx *> (last), &mnt_map); 3380 any_rewritten = true; 3381 } 3382 } 3383 3384 if (dominance_invalidated) 3385 { 3386 free_dominance_info (CDI_DOMINATORS); 3387 free_dominance_info (CDI_POST_DOMINATORS); 3388 } 3389 3390 return any_rewritten ? TODO_update_ssa_only_virtuals : 0; 3391} 3392 3393} // anon namespace 3394 3395gimple_opt_pass * 3396make_pass_lower_resx (gcc::context *ctxt) 3397{ 3398 return new pass_lower_resx (ctxt); 3399} 3400 3401/* Try to optimize var = {v} {CLOBBER} stmts followed just by 3402 external throw. */ 3403 3404static void 3405optimize_clobbers (basic_block bb) 3406{ 3407 gimple_stmt_iterator gsi = gsi_last_bb (bb); 3408 bool any_clobbers = false; 3409 bool seen_stack_restore = false; 3410 edge_iterator ei; 3411 edge e; 3412 3413 /* Only optimize anything if the bb contains at least one clobber, 3414 ends with resx (checked by caller), optionally contains some 3415 debug stmts or labels, or at most one __builtin_stack_restore 3416 call, and has an incoming EH edge. */ 3417 for (gsi_prev (&gsi); !gsi_end_p (gsi); gsi_prev (&gsi)) 3418 { 3419 gimple stmt = gsi_stmt (gsi); 3420 if (is_gimple_debug (stmt)) 3421 continue; 3422 if (gimple_clobber_p (stmt)) 3423 { 3424 any_clobbers = true; 3425 continue; 3426 } 3427 if (!seen_stack_restore 3428 && gimple_call_builtin_p (stmt, BUILT_IN_STACK_RESTORE)) 3429 { 3430 seen_stack_restore = true; 3431 continue; 3432 } 3433 if (gimple_code (stmt) == GIMPLE_LABEL) 3434 break; 3435 return; 3436 } 3437 if (!any_clobbers) 3438 return; 3439 FOR_EACH_EDGE (e, ei, bb->preds) 3440 if (e->flags & EDGE_EH) 3441 break; 3442 if (e == NULL) 3443 return; 3444 gsi = gsi_last_bb (bb); 3445 for (gsi_prev (&gsi); !gsi_end_p (gsi); gsi_prev (&gsi)) 3446 { 3447 gimple stmt = gsi_stmt (gsi); 3448 if (!gimple_clobber_p (stmt)) 3449 continue; 3450 unlink_stmt_vdef (stmt); 3451 gsi_remove (&gsi, true); 3452 release_defs (stmt); 3453 } 3454} 3455 3456/* Try to sink var = {v} {CLOBBER} stmts followed just by 3457 internal throw to successor BB. */ 3458 3459static int 3460sink_clobbers (basic_block bb) 3461{ 3462 edge e; 3463 edge_iterator ei; 3464 gimple_stmt_iterator gsi, dgsi; 3465 basic_block succbb; 3466 bool any_clobbers = false; 3467 unsigned todo = 0; 3468 3469 /* Only optimize if BB has a single EH successor and 3470 all predecessor edges are EH too. */ 3471 if (!single_succ_p (bb) 3472 || (single_succ_edge (bb)->flags & EDGE_EH) == 0) 3473 return 0; 3474 3475 FOR_EACH_EDGE (e, ei, bb->preds) 3476 { 3477 if ((e->flags & EDGE_EH) == 0) 3478 return 0; 3479 } 3480 3481 /* And BB contains only CLOBBER stmts before the final 3482 RESX. */ 3483 gsi = gsi_last_bb (bb); 3484 for (gsi_prev (&gsi); !gsi_end_p (gsi); gsi_prev (&gsi)) 3485 { 3486 gimple stmt = gsi_stmt (gsi); 3487 if (is_gimple_debug (stmt)) 3488 continue; 3489 if (gimple_code (stmt) == GIMPLE_LABEL) 3490 break; 3491 if (!gimple_clobber_p (stmt)) 3492 return 0; 3493 any_clobbers = true; 3494 } 3495 if (!any_clobbers) 3496 return 0; 3497 3498 edge succe = single_succ_edge (bb); 3499 succbb = succe->dest; 3500 3501 /* See if there is a virtual PHI node to take an updated virtual 3502 operand from. */ 3503 gphi *vphi = NULL; 3504 tree vuse = NULL_TREE; 3505 for (gphi_iterator gpi = gsi_start_phis (succbb); 3506 !gsi_end_p (gpi); gsi_next (&gpi)) 3507 { 3508 tree res = gimple_phi_result (gpi.phi ()); 3509 if (virtual_operand_p (res)) 3510 { 3511 vphi = gpi.phi (); 3512 vuse = res; 3513 break; 3514 } 3515 } 3516 3517 dgsi = gsi_after_labels (succbb); 3518 gsi = gsi_last_bb (bb); 3519 for (gsi_prev (&gsi); !gsi_end_p (gsi); gsi_prev (&gsi)) 3520 { 3521 gimple stmt = gsi_stmt (gsi); 3522 tree lhs; 3523 if (is_gimple_debug (stmt)) 3524 continue; 3525 if (gimple_code (stmt) == GIMPLE_LABEL) 3526 break; 3527 lhs = gimple_assign_lhs (stmt); 3528 /* Unfortunately we don't have dominance info updated at this 3529 point, so checking if 3530 dominated_by_p (CDI_DOMINATORS, succbb, 3531 gimple_bb (SSA_NAME_DEF_STMT (TREE_OPERAND (lhs, 0))) 3532 would be too costly. Thus, avoid sinking any clobbers that 3533 refer to non-(D) SSA_NAMEs. */ 3534 if (TREE_CODE (lhs) == MEM_REF 3535 && TREE_CODE (TREE_OPERAND (lhs, 0)) == SSA_NAME 3536 && !SSA_NAME_IS_DEFAULT_DEF (TREE_OPERAND (lhs, 0))) 3537 { 3538 unlink_stmt_vdef (stmt); 3539 gsi_remove (&gsi, true); 3540 release_defs (stmt); 3541 continue; 3542 } 3543 3544 /* As we do not change stmt order when sinking across a 3545 forwarder edge we can keep virtual operands in place. */ 3546 gsi_remove (&gsi, false); 3547 gsi_insert_before (&dgsi, stmt, GSI_NEW_STMT); 3548 3549 /* But adjust virtual operands if we sunk across a PHI node. */ 3550 if (vuse) 3551 { 3552 gimple use_stmt; 3553 imm_use_iterator iter; 3554 use_operand_p use_p; 3555 FOR_EACH_IMM_USE_STMT (use_stmt, iter, vuse) 3556 FOR_EACH_IMM_USE_ON_STMT (use_p, iter) 3557 SET_USE (use_p, gimple_vdef (stmt)); 3558 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (vuse)) 3559 { 3560 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (gimple_vdef (stmt)) = 1; 3561 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (vuse) = 0; 3562 } 3563 /* Adjust the incoming virtual operand. */ 3564 SET_USE (PHI_ARG_DEF_PTR_FROM_EDGE (vphi, succe), gimple_vuse (stmt)); 3565 SET_USE (gimple_vuse_op (stmt), vuse); 3566 } 3567 /* If there isn't a single predecessor but no virtual PHI node 3568 arrange for virtual operands to be renamed. */ 3569 else if (gimple_vuse_op (stmt) != NULL_USE_OPERAND_P 3570 && !single_pred_p (succbb)) 3571 { 3572 /* In this case there will be no use of the VDEF of this stmt. 3573 ??? Unless this is a secondary opportunity and we have not 3574 removed unreachable blocks yet, so we cannot assert this. 3575 Which also means we will end up renaming too many times. */ 3576 SET_USE (gimple_vuse_op (stmt), gimple_vop (cfun)); 3577 mark_virtual_operands_for_renaming (cfun); 3578 todo |= TODO_update_ssa_only_virtuals; 3579 } 3580 } 3581 3582 return todo; 3583} 3584 3585/* At the end of inlining, we can lower EH_DISPATCH. Return true when 3586 we have found some duplicate labels and removed some edges. */ 3587 3588static bool 3589lower_eh_dispatch (basic_block src, geh_dispatch *stmt) 3590{ 3591 gimple_stmt_iterator gsi; 3592 int region_nr; 3593 eh_region r; 3594 tree filter, fn; 3595 gimple x; 3596 bool redirected = false; 3597 3598 region_nr = gimple_eh_dispatch_region (stmt); 3599 r = get_eh_region_from_number (region_nr); 3600 3601 gsi = gsi_last_bb (src); 3602 3603 switch (r->type) 3604 { 3605 case ERT_TRY: 3606 { 3607 auto_vec<tree> labels; 3608 tree default_label = NULL; 3609 eh_catch c; 3610 edge_iterator ei; 3611 edge e; 3612 hash_set<tree> seen_values; 3613 3614 /* Collect the labels for a switch. Zero the post_landing_pad 3615 field becase we'll no longer have anything keeping these labels 3616 in existence and the optimizer will be free to merge these 3617 blocks at will. */ 3618 for (c = r->u.eh_try.first_catch; c ; c = c->next_catch) 3619 { 3620 tree tp_node, flt_node, lab = c->label; 3621 bool have_label = false; 3622 3623 c->label = NULL; 3624 tp_node = c->type_list; 3625 flt_node = c->filter_list; 3626 3627 if (tp_node == NULL) 3628 { 3629 default_label = lab; 3630 break; 3631 } 3632 do 3633 { 3634 /* Filter out duplicate labels that arise when this handler 3635 is shadowed by an earlier one. When no labels are 3636 attached to the handler anymore, we remove 3637 the corresponding edge and then we delete unreachable 3638 blocks at the end of this pass. */ 3639 if (! seen_values.contains (TREE_VALUE (flt_node))) 3640 { 3641 tree t = build_case_label (TREE_VALUE (flt_node), 3642 NULL, lab); 3643 labels.safe_push (t); 3644 seen_values.add (TREE_VALUE (flt_node)); 3645 have_label = true; 3646 } 3647 3648 tp_node = TREE_CHAIN (tp_node); 3649 flt_node = TREE_CHAIN (flt_node); 3650 } 3651 while (tp_node); 3652 if (! have_label) 3653 { 3654 remove_edge (find_edge (src, label_to_block (lab))); 3655 redirected = true; 3656 } 3657 } 3658 3659 /* Clean up the edge flags. */ 3660 FOR_EACH_EDGE (e, ei, src->succs) 3661 { 3662 if (e->flags & EDGE_FALLTHRU) 3663 { 3664 /* If there was no catch-all, use the fallthru edge. */ 3665 if (default_label == NULL) 3666 default_label = gimple_block_label (e->dest); 3667 e->flags &= ~EDGE_FALLTHRU; 3668 } 3669 } 3670 gcc_assert (default_label != NULL); 3671 3672 /* Don't generate a switch if there's only a default case. 3673 This is common in the form of try { A; } catch (...) { B; }. */ 3674 if (!labels.exists ()) 3675 { 3676 e = single_succ_edge (src); 3677 e->flags |= EDGE_FALLTHRU; 3678 } 3679 else 3680 { 3681 fn = builtin_decl_implicit (BUILT_IN_EH_FILTER); 3682 x = gimple_build_call (fn, 1, build_int_cst (integer_type_node, 3683 region_nr)); 3684 filter = create_tmp_var (TREE_TYPE (TREE_TYPE (fn))); 3685 filter = make_ssa_name (filter, x); 3686 gimple_call_set_lhs (x, filter); 3687 gsi_insert_before (&gsi, x, GSI_SAME_STMT); 3688 3689 /* Turn the default label into a default case. */ 3690 default_label = build_case_label (NULL, NULL, default_label); 3691 sort_case_labels (labels); 3692 3693 x = gimple_build_switch (filter, default_label, labels); 3694 gsi_insert_before (&gsi, x, GSI_SAME_STMT); 3695 } 3696 } 3697 break; 3698 3699 case ERT_ALLOWED_EXCEPTIONS: 3700 { 3701 edge b_e = BRANCH_EDGE (src); 3702 edge f_e = FALLTHRU_EDGE (src); 3703 3704 fn = builtin_decl_implicit (BUILT_IN_EH_FILTER); 3705 x = gimple_build_call (fn, 1, build_int_cst (integer_type_node, 3706 region_nr)); 3707 filter = create_tmp_var (TREE_TYPE (TREE_TYPE (fn))); 3708 filter = make_ssa_name (filter, x); 3709 gimple_call_set_lhs (x, filter); 3710 gsi_insert_before (&gsi, x, GSI_SAME_STMT); 3711 3712 r->u.allowed.label = NULL; 3713 x = gimple_build_cond (EQ_EXPR, filter, 3714 build_int_cst (TREE_TYPE (filter), 3715 r->u.allowed.filter), 3716 NULL_TREE, NULL_TREE); 3717 gsi_insert_before (&gsi, x, GSI_SAME_STMT); 3718 3719 b_e->flags = b_e->flags | EDGE_TRUE_VALUE; 3720 f_e->flags = (f_e->flags & ~EDGE_FALLTHRU) | EDGE_FALSE_VALUE; 3721 } 3722 break; 3723 3724 default: 3725 gcc_unreachable (); 3726 } 3727 3728 /* Replace the EH_DISPATCH with the SWITCH or COND generated above. */ 3729 gsi_remove (&gsi, true); 3730 return redirected; 3731} 3732 3733namespace { 3734 3735const pass_data pass_data_lower_eh_dispatch = 3736{ 3737 GIMPLE_PASS, /* type */ 3738 "ehdisp", /* name */ 3739 OPTGROUP_NONE, /* optinfo_flags */ 3740 TV_TREE_EH, /* tv_id */ 3741 PROP_gimple_lcf, /* properties_required */ 3742 0, /* properties_provided */ 3743 0, /* properties_destroyed */ 3744 0, /* todo_flags_start */ 3745 0, /* todo_flags_finish */ 3746}; 3747 3748class pass_lower_eh_dispatch : public gimple_opt_pass 3749{ 3750public: 3751 pass_lower_eh_dispatch (gcc::context *ctxt) 3752 : gimple_opt_pass (pass_data_lower_eh_dispatch, ctxt) 3753 {} 3754 3755 /* opt_pass methods: */ 3756 virtual bool gate (function *fun) { return fun->eh->region_tree != NULL; } 3757 virtual unsigned int execute (function *); 3758 3759}; // class pass_lower_eh_dispatch 3760 3761unsigned 3762pass_lower_eh_dispatch::execute (function *fun) 3763{ 3764 basic_block bb; 3765 int flags = 0; 3766 bool redirected = false; 3767 3768 assign_filter_values (); 3769 3770 FOR_EACH_BB_FN (bb, fun) 3771 { 3772 gimple last = last_stmt (bb); 3773 if (last == NULL) 3774 continue; 3775 if (gimple_code (last) == GIMPLE_EH_DISPATCH) 3776 { 3777 redirected |= lower_eh_dispatch (bb, 3778 as_a <geh_dispatch *> (last)); 3779 flags |= TODO_update_ssa_only_virtuals; 3780 } 3781 else if (gimple_code (last) == GIMPLE_RESX) 3782 { 3783 if (stmt_can_throw_external (last)) 3784 optimize_clobbers (bb); 3785 else 3786 flags |= sink_clobbers (bb); 3787 } 3788 } 3789 3790 if (redirected) 3791 delete_unreachable_blocks (); 3792 return flags; 3793} 3794 3795} // anon namespace 3796 3797gimple_opt_pass * 3798make_pass_lower_eh_dispatch (gcc::context *ctxt) 3799{ 3800 return new pass_lower_eh_dispatch (ctxt); 3801} 3802 3803/* Walk statements, see what regions and, optionally, landing pads 3804 are really referenced. 3805 3806 Returns in R_REACHABLEP an sbitmap with bits set for reachable regions, 3807 and in LP_REACHABLE an sbitmap with bits set for reachable landing pads. 3808 3809 Passing NULL for LP_REACHABLE is valid, in this case only reachable 3810 regions are marked. 3811 3812 The caller is responsible for freeing the returned sbitmaps. */ 3813 3814static void 3815mark_reachable_handlers (sbitmap *r_reachablep, sbitmap *lp_reachablep) 3816{ 3817 sbitmap r_reachable, lp_reachable; 3818 basic_block bb; 3819 bool mark_landing_pads = (lp_reachablep != NULL); 3820 gcc_checking_assert (r_reachablep != NULL); 3821 3822 r_reachable = sbitmap_alloc (cfun->eh->region_array->length ()); 3823 bitmap_clear (r_reachable); 3824 *r_reachablep = r_reachable; 3825 3826 if (mark_landing_pads) 3827 { 3828 lp_reachable = sbitmap_alloc (cfun->eh->lp_array->length ()); 3829 bitmap_clear (lp_reachable); 3830 *lp_reachablep = lp_reachable; 3831 } 3832 else 3833 lp_reachable = NULL; 3834 3835 FOR_EACH_BB_FN (bb, cfun) 3836 { 3837 gimple_stmt_iterator gsi; 3838 3839 for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi)) 3840 { 3841 gimple stmt = gsi_stmt (gsi); 3842 3843 if (mark_landing_pads) 3844 { 3845 int lp_nr = lookup_stmt_eh_lp (stmt); 3846 3847 /* Negative LP numbers are MUST_NOT_THROW regions which 3848 are not considered BB enders. */ 3849 if (lp_nr < 0) 3850 bitmap_set_bit (r_reachable, -lp_nr); 3851 3852 /* Positive LP numbers are real landing pads, and BB enders. */ 3853 else if (lp_nr > 0) 3854 { 3855 gcc_assert (gsi_one_before_end_p (gsi)); 3856 eh_region region = get_eh_region_from_lp_number (lp_nr); 3857 bitmap_set_bit (r_reachable, region->index); 3858 bitmap_set_bit (lp_reachable, lp_nr); 3859 } 3860 } 3861 3862 /* Avoid removing regions referenced from RESX/EH_DISPATCH. */ 3863 switch (gimple_code (stmt)) 3864 { 3865 case GIMPLE_RESX: 3866 bitmap_set_bit (r_reachable, 3867 gimple_resx_region (as_a <gresx *> (stmt))); 3868 break; 3869 case GIMPLE_EH_DISPATCH: 3870 bitmap_set_bit (r_reachable, 3871 gimple_eh_dispatch_region ( 3872 as_a <geh_dispatch *> (stmt))); 3873 break; 3874 case GIMPLE_CALL: 3875 if (gimple_call_builtin_p (stmt, BUILT_IN_EH_COPY_VALUES)) 3876 for (int i = 0; i < 2; ++i) 3877 { 3878 tree rt = gimple_call_arg (stmt, i); 3879 HOST_WIDE_INT ri = tree_to_shwi (rt); 3880 3881 gcc_assert (ri = (int)ri); 3882 bitmap_set_bit (r_reachable, ri); 3883 } 3884 break; 3885 default: 3886 break; 3887 } 3888 } 3889 } 3890} 3891 3892/* Remove unreachable handlers and unreachable landing pads. */ 3893 3894static void 3895remove_unreachable_handlers (void) 3896{ 3897 sbitmap r_reachable, lp_reachable; 3898 eh_region region; 3899 eh_landing_pad lp; 3900 unsigned i; 3901 3902 mark_reachable_handlers (&r_reachable, &lp_reachable); 3903 3904 if (dump_file) 3905 { 3906 fprintf (dump_file, "Before removal of unreachable regions:\n"); 3907 dump_eh_tree (dump_file, cfun); 3908 fprintf (dump_file, "Reachable regions: "); 3909 dump_bitmap_file (dump_file, r_reachable); 3910 fprintf (dump_file, "Reachable landing pads: "); 3911 dump_bitmap_file (dump_file, lp_reachable); 3912 } 3913 3914 if (dump_file) 3915 { 3916 FOR_EACH_VEC_SAFE_ELT (cfun->eh->region_array, i, region) 3917 if (region && !bitmap_bit_p (r_reachable, region->index)) 3918 fprintf (dump_file, 3919 "Removing unreachable region %d\n", 3920 region->index); 3921 } 3922 3923 remove_unreachable_eh_regions (r_reachable); 3924 3925 FOR_EACH_VEC_SAFE_ELT (cfun->eh->lp_array, i, lp) 3926 if (lp && !bitmap_bit_p (lp_reachable, lp->index)) 3927 { 3928 if (dump_file) 3929 fprintf (dump_file, 3930 "Removing unreachable landing pad %d\n", 3931 lp->index); 3932 remove_eh_landing_pad (lp); 3933 } 3934 3935 if (dump_file) 3936 { 3937 fprintf (dump_file, "\n\nAfter removal of unreachable regions:\n"); 3938 dump_eh_tree (dump_file, cfun); 3939 fprintf (dump_file, "\n\n"); 3940 } 3941 3942 sbitmap_free (r_reachable); 3943 sbitmap_free (lp_reachable); 3944 3945#ifdef ENABLE_CHECKING 3946 verify_eh_tree (cfun); 3947#endif 3948} 3949 3950/* Remove unreachable handlers if any landing pads have been removed after 3951 last ehcleanup pass (due to gimple_purge_dead_eh_edges). */ 3952 3953void 3954maybe_remove_unreachable_handlers (void) 3955{ 3956 eh_landing_pad lp; 3957 unsigned i; 3958 3959 if (cfun->eh == NULL) 3960 return; 3961 3962 FOR_EACH_VEC_SAFE_ELT (cfun->eh->lp_array, i, lp) 3963 if (lp && lp->post_landing_pad) 3964 { 3965 if (label_to_block (lp->post_landing_pad) == NULL) 3966 { 3967 remove_unreachable_handlers (); 3968 return; 3969 } 3970 } 3971} 3972 3973/* Remove regions that do not have landing pads. This assumes 3974 that remove_unreachable_handlers has already been run, and 3975 that we've just manipulated the landing pads since then. 3976 3977 Preserve regions with landing pads and regions that prevent 3978 exceptions from propagating further, even if these regions 3979 are not reachable. */ 3980 3981static void 3982remove_unreachable_handlers_no_lp (void) 3983{ 3984 eh_region region; 3985 sbitmap r_reachable; 3986 unsigned i; 3987 3988 mark_reachable_handlers (&r_reachable, /*lp_reachablep=*/NULL); 3989 3990 FOR_EACH_VEC_SAFE_ELT (cfun->eh->region_array, i, region) 3991 { 3992 if (! region) 3993 continue; 3994 3995 if (region->landing_pads != NULL 3996 || region->type == ERT_MUST_NOT_THROW) 3997 bitmap_set_bit (r_reachable, region->index); 3998 3999 if (dump_file 4000 && !bitmap_bit_p (r_reachable, region->index)) 4001 fprintf (dump_file, 4002 "Removing unreachable region %d\n", 4003 region->index); 4004 } 4005 4006 remove_unreachable_eh_regions (r_reachable); 4007 4008 sbitmap_free (r_reachable); 4009} 4010 4011/* Undo critical edge splitting on an EH landing pad. Earlier, we 4012 optimisticaly split all sorts of edges, including EH edges. The 4013 optimization passes in between may not have needed them; if not, 4014 we should undo the split. 4015 4016 Recognize this case by having one EH edge incoming to the BB and 4017 one normal edge outgoing; BB should be empty apart from the 4018 post_landing_pad label. 4019 4020 Note that this is slightly different from the empty handler case 4021 handled by cleanup_empty_eh, in that the actual handler may yet 4022 have actual code but the landing pad has been separated from the 4023 handler. As such, cleanup_empty_eh relies on this transformation 4024 having been done first. */ 4025 4026static bool 4027unsplit_eh (eh_landing_pad lp) 4028{ 4029 basic_block bb = label_to_block (lp->post_landing_pad); 4030 gimple_stmt_iterator gsi; 4031 edge e_in, e_out; 4032 4033 /* Quickly check the edge counts on BB for singularity. */ 4034 if (!single_pred_p (bb) || !single_succ_p (bb)) 4035 return false; 4036 e_in = single_pred_edge (bb); 4037 e_out = single_succ_edge (bb); 4038 4039 /* Input edge must be EH and output edge must be normal. */ 4040 if ((e_in->flags & EDGE_EH) == 0 || (e_out->flags & EDGE_EH) != 0) 4041 return false; 4042 4043 /* The block must be empty except for the labels and debug insns. */ 4044 gsi = gsi_after_labels (bb); 4045 if (!gsi_end_p (gsi) && is_gimple_debug (gsi_stmt (gsi))) 4046 gsi_next_nondebug (&gsi); 4047 if (!gsi_end_p (gsi)) 4048 return false; 4049 4050 /* The destination block must not already have a landing pad 4051 for a different region. */ 4052 for (gsi = gsi_start_bb (e_out->dest); !gsi_end_p (gsi); gsi_next (&gsi)) 4053 { 4054 glabel *label_stmt = dyn_cast <glabel *> (gsi_stmt (gsi)); 4055 tree lab; 4056 int lp_nr; 4057 4058 if (!label_stmt) 4059 break; 4060 lab = gimple_label_label (label_stmt); 4061 lp_nr = EH_LANDING_PAD_NR (lab); 4062 if (lp_nr && get_eh_region_from_lp_number (lp_nr) != lp->region) 4063 return false; 4064 } 4065 4066 /* The new destination block must not already be a destination of 4067 the source block, lest we merge fallthru and eh edges and get 4068 all sorts of confused. */ 4069 if (find_edge (e_in->src, e_out->dest)) 4070 return false; 4071 4072 /* ??? We can get degenerate phis due to cfg cleanups. I would have 4073 thought this should have been cleaned up by a phicprop pass, but 4074 that doesn't appear to handle virtuals. Propagate by hand. */ 4075 if (!gimple_seq_empty_p (phi_nodes (bb))) 4076 { 4077 for (gphi_iterator gpi = gsi_start_phis (bb); !gsi_end_p (gpi); ) 4078 { 4079 gimple use_stmt; 4080 gphi *phi = gpi.phi (); 4081 tree lhs = gimple_phi_result (phi); 4082 tree rhs = gimple_phi_arg_def (phi, 0); 4083 use_operand_p use_p; 4084 imm_use_iterator iter; 4085 4086 FOR_EACH_IMM_USE_STMT (use_stmt, iter, lhs) 4087 { 4088 FOR_EACH_IMM_USE_ON_STMT (use_p, iter) 4089 SET_USE (use_p, rhs); 4090 } 4091 4092 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (lhs)) 4093 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (rhs) = 1; 4094 4095 remove_phi_node (&gpi, true); 4096 } 4097 } 4098 4099 if (dump_file && (dump_flags & TDF_DETAILS)) 4100 fprintf (dump_file, "Unsplit EH landing pad %d to block %i.\n", 4101 lp->index, e_out->dest->index); 4102 4103 /* Redirect the edge. Since redirect_eh_edge_1 expects to be moving 4104 a successor edge, humor it. But do the real CFG change with the 4105 predecessor of E_OUT in order to preserve the ordering of arguments 4106 to the PHI nodes in E_OUT->DEST. */ 4107 redirect_eh_edge_1 (e_in, e_out->dest, false); 4108 redirect_edge_pred (e_out, e_in->src); 4109 e_out->flags = e_in->flags; 4110 e_out->probability = e_in->probability; 4111 e_out->count = e_in->count; 4112 remove_edge (e_in); 4113 4114 return true; 4115} 4116 4117/* Examine each landing pad block and see if it matches unsplit_eh. */ 4118 4119static bool 4120unsplit_all_eh (void) 4121{ 4122 bool changed = false; 4123 eh_landing_pad lp; 4124 int i; 4125 4126 for (i = 1; vec_safe_iterate (cfun->eh->lp_array, i, &lp); ++i) 4127 if (lp) 4128 changed |= unsplit_eh (lp); 4129 4130 return changed; 4131} 4132 4133/* A subroutine of cleanup_empty_eh. Redirect all EH edges incoming 4134 to OLD_BB to NEW_BB; return true on success, false on failure. 4135 4136 OLD_BB_OUT is the edge into NEW_BB from OLD_BB, so if we miss any 4137 PHI variables from OLD_BB we can pick them up from OLD_BB_OUT. 4138 Virtual PHIs may be deleted and marked for renaming. */ 4139 4140static bool 4141cleanup_empty_eh_merge_phis (basic_block new_bb, basic_block old_bb, 4142 edge old_bb_out, bool change_region) 4143{ 4144 gphi_iterator ngsi, ogsi; 4145 edge_iterator ei; 4146 edge e; 4147 bitmap ophi_handled; 4148 4149 /* The destination block must not be a regular successor for any 4150 of the preds of the landing pad. Thus, avoid turning 4151 <..> 4152 | \ EH 4153 | <..> 4154 | / 4155 <..> 4156 into 4157 <..> 4158 | | EH 4159 <..> 4160 which CFG verification would choke on. See PR45172 and PR51089. */ 4161 FOR_EACH_EDGE (e, ei, old_bb->preds) 4162 if (find_edge (e->src, new_bb)) 4163 return false; 4164 4165 FOR_EACH_EDGE (e, ei, old_bb->preds) 4166 redirect_edge_var_map_clear (e); 4167 4168 ophi_handled = BITMAP_ALLOC (NULL); 4169 4170 /* First, iterate through the PHIs on NEW_BB and set up the edge_var_map 4171 for the edges we're going to move. */ 4172 for (ngsi = gsi_start_phis (new_bb); !gsi_end_p (ngsi); gsi_next (&ngsi)) 4173 { 4174 gphi *ophi, *nphi = ngsi.phi (); 4175 tree nresult, nop; 4176 4177 nresult = gimple_phi_result (nphi); 4178 nop = gimple_phi_arg_def (nphi, old_bb_out->dest_idx); 4179 4180 /* Find the corresponding PHI in OLD_BB so we can forward-propagate 4181 the source ssa_name. */ 4182 ophi = NULL; 4183 for (ogsi = gsi_start_phis (old_bb); !gsi_end_p (ogsi); gsi_next (&ogsi)) 4184 { 4185 ophi = ogsi.phi (); 4186 if (gimple_phi_result (ophi) == nop) 4187 break; 4188 ophi = NULL; 4189 } 4190 4191 /* If we did find the corresponding PHI, copy those inputs. */ 4192 if (ophi) 4193 { 4194 /* If NOP is used somewhere else beyond phis in new_bb, give up. */ 4195 if (!has_single_use (nop)) 4196 { 4197 imm_use_iterator imm_iter; 4198 use_operand_p use_p; 4199 4200 FOR_EACH_IMM_USE_FAST (use_p, imm_iter, nop) 4201 { 4202 if (!gimple_debug_bind_p (USE_STMT (use_p)) 4203 && (gimple_code (USE_STMT (use_p)) != GIMPLE_PHI 4204 || gimple_bb (USE_STMT (use_p)) != new_bb)) 4205 goto fail; 4206 } 4207 } 4208 bitmap_set_bit (ophi_handled, SSA_NAME_VERSION (nop)); 4209 FOR_EACH_EDGE (e, ei, old_bb->preds) 4210 { 4211 location_t oloc; 4212 tree oop; 4213 4214 if ((e->flags & EDGE_EH) == 0) 4215 continue; 4216 oop = gimple_phi_arg_def (ophi, e->dest_idx); 4217 oloc = gimple_phi_arg_location (ophi, e->dest_idx); 4218 redirect_edge_var_map_add (e, nresult, oop, oloc); 4219 } 4220 } 4221 /* If we didn't find the PHI, if it's a real variable or a VOP, we know 4222 from the fact that OLD_BB is tree_empty_eh_handler_p that the 4223 variable is unchanged from input to the block and we can simply 4224 re-use the input to NEW_BB from the OLD_BB_OUT edge. */ 4225 else 4226 { 4227 location_t nloc 4228 = gimple_phi_arg_location (nphi, old_bb_out->dest_idx); 4229 FOR_EACH_EDGE (e, ei, old_bb->preds) 4230 redirect_edge_var_map_add (e, nresult, nop, nloc); 4231 } 4232 } 4233 4234 /* Second, verify that all PHIs from OLD_BB have been handled. If not, 4235 we don't know what values from the other edges into NEW_BB to use. */ 4236 for (ogsi = gsi_start_phis (old_bb); !gsi_end_p (ogsi); gsi_next (&ogsi)) 4237 { 4238 gphi *ophi = ogsi.phi (); 4239 tree oresult = gimple_phi_result (ophi); 4240 if (!bitmap_bit_p (ophi_handled, SSA_NAME_VERSION (oresult))) 4241 goto fail; 4242 } 4243 4244 /* Finally, move the edges and update the PHIs. */ 4245 for (ei = ei_start (old_bb->preds); (e = ei_safe_edge (ei)); ) 4246 if (e->flags & EDGE_EH) 4247 { 4248 /* ??? CFG manipluation routines do not try to update loop 4249 form on edge redirection. Do so manually here for now. */ 4250 /* If we redirect a loop entry or latch edge that will either create 4251 a multiple entry loop or rotate the loop. If the loops merge 4252 we may have created a loop with multiple latches. 4253 All of this isn't easily fixed thus cancel the affected loop 4254 and mark the other loop as possibly having multiple latches. */ 4255 if (e->dest == e->dest->loop_father->header) 4256 { 4257 mark_loop_for_removal (e->dest->loop_father); 4258 new_bb->loop_father->latch = NULL; 4259 loops_state_set (LOOPS_MAY_HAVE_MULTIPLE_LATCHES); 4260 } 4261 redirect_eh_edge_1 (e, new_bb, change_region); 4262 redirect_edge_succ (e, new_bb); 4263 flush_pending_stmts (e); 4264 } 4265 else 4266 ei_next (&ei); 4267 4268 BITMAP_FREE (ophi_handled); 4269 return true; 4270 4271 fail: 4272 FOR_EACH_EDGE (e, ei, old_bb->preds) 4273 redirect_edge_var_map_clear (e); 4274 BITMAP_FREE (ophi_handled); 4275 return false; 4276} 4277 4278/* A subroutine of cleanup_empty_eh. Move a landing pad LP from its 4279 old region to NEW_REGION at BB. */ 4280 4281static void 4282cleanup_empty_eh_move_lp (basic_block bb, edge e_out, 4283 eh_landing_pad lp, eh_region new_region) 4284{ 4285 gimple_stmt_iterator gsi; 4286 eh_landing_pad *pp; 4287 4288 for (pp = &lp->region->landing_pads; *pp != lp; pp = &(*pp)->next_lp) 4289 continue; 4290 *pp = lp->next_lp; 4291 4292 lp->region = new_region; 4293 lp->next_lp = new_region->landing_pads; 4294 new_region->landing_pads = lp; 4295 4296 /* Delete the RESX that was matched within the empty handler block. */ 4297 gsi = gsi_last_bb (bb); 4298 unlink_stmt_vdef (gsi_stmt (gsi)); 4299 gsi_remove (&gsi, true); 4300 4301 /* Clean up E_OUT for the fallthru. */ 4302 e_out->flags = (e_out->flags & ~EDGE_EH) | EDGE_FALLTHRU; 4303 e_out->probability = REG_BR_PROB_BASE; 4304} 4305 4306/* A subroutine of cleanup_empty_eh. Handle more complex cases of 4307 unsplitting than unsplit_eh was prepared to handle, e.g. when 4308 multiple incoming edges and phis are involved. */ 4309 4310static bool 4311cleanup_empty_eh_unsplit (basic_block bb, edge e_out, eh_landing_pad lp) 4312{ 4313 gimple_stmt_iterator gsi; 4314 tree lab; 4315 4316 /* We really ought not have totally lost everything following 4317 a landing pad label. Given that BB is empty, there had better 4318 be a successor. */ 4319 gcc_assert (e_out != NULL); 4320 4321 /* The destination block must not already have a landing pad 4322 for a different region. */ 4323 lab = NULL; 4324 for (gsi = gsi_start_bb (e_out->dest); !gsi_end_p (gsi); gsi_next (&gsi)) 4325 { 4326 glabel *stmt = dyn_cast <glabel *> (gsi_stmt (gsi)); 4327 int lp_nr; 4328 4329 if (!stmt) 4330 break; 4331 lab = gimple_label_label (stmt); 4332 lp_nr = EH_LANDING_PAD_NR (lab); 4333 if (lp_nr && get_eh_region_from_lp_number (lp_nr) != lp->region) 4334 return false; 4335 } 4336 4337 /* Attempt to move the PHIs into the successor block. */ 4338 if (cleanup_empty_eh_merge_phis (e_out->dest, bb, e_out, false)) 4339 { 4340 if (dump_file && (dump_flags & TDF_DETAILS)) 4341 fprintf (dump_file, 4342 "Unsplit EH landing pad %d to block %i " 4343 "(via cleanup_empty_eh).\n", 4344 lp->index, e_out->dest->index); 4345 return true; 4346 } 4347 4348 return false; 4349} 4350 4351/* Return true if edge E_FIRST is part of an empty infinite loop 4352 or leads to such a loop through a series of single successor 4353 empty bbs. */ 4354 4355static bool 4356infinite_empty_loop_p (edge e_first) 4357{ 4358 bool inf_loop = false; 4359 edge e; 4360 4361 if (e_first->dest == e_first->src) 4362 return true; 4363 4364 e_first->src->aux = (void *) 1; 4365 for (e = e_first; single_succ_p (e->dest); e = single_succ_edge (e->dest)) 4366 { 4367 gimple_stmt_iterator gsi; 4368 if (e->dest->aux) 4369 { 4370 inf_loop = true; 4371 break; 4372 } 4373 e->dest->aux = (void *) 1; 4374 gsi = gsi_after_labels (e->dest); 4375 if (!gsi_end_p (gsi) && is_gimple_debug (gsi_stmt (gsi))) 4376 gsi_next_nondebug (&gsi); 4377 if (!gsi_end_p (gsi)) 4378 break; 4379 } 4380 e_first->src->aux = NULL; 4381 for (e = e_first; e->dest->aux; e = single_succ_edge (e->dest)) 4382 e->dest->aux = NULL; 4383 4384 return inf_loop; 4385} 4386 4387/* Examine the block associated with LP to determine if it's an empty 4388 handler for its EH region. If so, attempt to redirect EH edges to 4389 an outer region. Return true the CFG was updated in any way. This 4390 is similar to jump forwarding, just across EH edges. */ 4391 4392static bool 4393cleanup_empty_eh (eh_landing_pad lp) 4394{ 4395 basic_block bb = label_to_block (lp->post_landing_pad); 4396 gimple_stmt_iterator gsi; 4397 gimple resx; 4398 eh_region new_region; 4399 edge_iterator ei; 4400 edge e, e_out; 4401 bool has_non_eh_pred; 4402 bool ret = false; 4403 int new_lp_nr; 4404 4405 /* There can be zero or one edges out of BB. This is the quickest test. */ 4406 switch (EDGE_COUNT (bb->succs)) 4407 { 4408 case 0: 4409 e_out = NULL; 4410 break; 4411 case 1: 4412 e_out = single_succ_edge (bb); 4413 break; 4414 default: 4415 return false; 4416 } 4417 4418 resx = last_stmt (bb); 4419 if (resx && is_gimple_resx (resx)) 4420 { 4421 if (stmt_can_throw_external (resx)) 4422 optimize_clobbers (bb); 4423 else if (sink_clobbers (bb)) 4424 ret = true; 4425 } 4426 4427 gsi = gsi_after_labels (bb); 4428 4429 /* Make sure to skip debug statements. */ 4430 if (!gsi_end_p (gsi) && is_gimple_debug (gsi_stmt (gsi))) 4431 gsi_next_nondebug (&gsi); 4432 4433 /* If the block is totally empty, look for more unsplitting cases. */ 4434 if (gsi_end_p (gsi)) 4435 { 4436 /* For the degenerate case of an infinite loop bail out. 4437 If bb has no successors and is totally empty, which can happen e.g. 4438 because of incorrect noreturn attribute, bail out too. */ 4439 if (e_out == NULL 4440 || infinite_empty_loop_p (e_out)) 4441 return ret; 4442 4443 return ret | cleanup_empty_eh_unsplit (bb, e_out, lp); 4444 } 4445 4446 /* The block should consist only of a single RESX statement, modulo a 4447 preceding call to __builtin_stack_restore if there is no outgoing 4448 edge, since the call can be eliminated in this case. */ 4449 resx = gsi_stmt (gsi); 4450 if (!e_out && gimple_call_builtin_p (resx, BUILT_IN_STACK_RESTORE)) 4451 { 4452 gsi_next (&gsi); 4453 resx = gsi_stmt (gsi); 4454 } 4455 if (!is_gimple_resx (resx)) 4456 return ret; 4457 gcc_assert (gsi_one_before_end_p (gsi)); 4458 4459 /* Determine if there are non-EH edges, or resx edges into the handler. */ 4460 has_non_eh_pred = false; 4461 FOR_EACH_EDGE (e, ei, bb->preds) 4462 if (!(e->flags & EDGE_EH)) 4463 has_non_eh_pred = true; 4464 4465 /* Find the handler that's outer of the empty handler by looking at 4466 where the RESX instruction was vectored. */ 4467 new_lp_nr = lookup_stmt_eh_lp (resx); 4468 new_region = get_eh_region_from_lp_number (new_lp_nr); 4469 4470 /* If there's no destination region within the current function, 4471 redirection is trivial via removing the throwing statements from 4472 the EH region, removing the EH edges, and allowing the block 4473 to go unreachable. */ 4474 if (new_region == NULL) 4475 { 4476 gcc_assert (e_out == NULL); 4477 for (ei = ei_start (bb->preds); (e = ei_safe_edge (ei)); ) 4478 if (e->flags & EDGE_EH) 4479 { 4480 gimple stmt = last_stmt (e->src); 4481 remove_stmt_from_eh_lp (stmt); 4482 remove_edge (e); 4483 } 4484 else 4485 ei_next (&ei); 4486 goto succeed; 4487 } 4488 4489 /* If the destination region is a MUST_NOT_THROW, allow the runtime 4490 to handle the abort and allow the blocks to go unreachable. */ 4491 if (new_region->type == ERT_MUST_NOT_THROW) 4492 { 4493 for (ei = ei_start (bb->preds); (e = ei_safe_edge (ei)); ) 4494 if (e->flags & EDGE_EH) 4495 { 4496 gimple stmt = last_stmt (e->src); 4497 remove_stmt_from_eh_lp (stmt); 4498 add_stmt_to_eh_lp (stmt, new_lp_nr); 4499 remove_edge (e); 4500 } 4501 else 4502 ei_next (&ei); 4503 goto succeed; 4504 } 4505 4506 /* Try to redirect the EH edges and merge the PHIs into the destination 4507 landing pad block. If the merge succeeds, we'll already have redirected 4508 all the EH edges. The handler itself will go unreachable if there were 4509 no normal edges. */ 4510 if (cleanup_empty_eh_merge_phis (e_out->dest, bb, e_out, true)) 4511 goto succeed; 4512 4513 /* Finally, if all input edges are EH edges, then we can (potentially) 4514 reduce the number of transfers from the runtime by moving the landing 4515 pad from the original region to the new region. This is a win when 4516 we remove the last CLEANUP region along a particular exception 4517 propagation path. Since nothing changes except for the region with 4518 which the landing pad is associated, the PHI nodes do not need to be 4519 adjusted at all. */ 4520 if (!has_non_eh_pred) 4521 { 4522 cleanup_empty_eh_move_lp (bb, e_out, lp, new_region); 4523 if (dump_file && (dump_flags & TDF_DETAILS)) 4524 fprintf (dump_file, "Empty EH handler %i moved to EH region %i.\n", 4525 lp->index, new_region->index); 4526 4527 /* ??? The CFG didn't change, but we may have rendered the 4528 old EH region unreachable. Trigger a cleanup there. */ 4529 return true; 4530 } 4531 4532 return ret; 4533 4534 succeed: 4535 if (dump_file && (dump_flags & TDF_DETAILS)) 4536 fprintf (dump_file, "Empty EH handler %i removed.\n", lp->index); 4537 remove_eh_landing_pad (lp); 4538 return true; 4539} 4540 4541/* Do a post-order traversal of the EH region tree. Examine each 4542 post_landing_pad block and see if we can eliminate it as empty. */ 4543 4544static bool 4545cleanup_all_empty_eh (void) 4546{ 4547 bool changed = false; 4548 eh_landing_pad lp; 4549 int i; 4550 4551 for (i = 1; vec_safe_iterate (cfun->eh->lp_array, i, &lp); ++i) 4552 if (lp) 4553 changed |= cleanup_empty_eh (lp); 4554 4555 return changed; 4556} 4557 4558/* Perform cleanups and lowering of exception handling 4559 1) cleanups regions with handlers doing nothing are optimized out 4560 2) MUST_NOT_THROW regions that became dead because of 1) are optimized out 4561 3) Info about regions that are containing instructions, and regions 4562 reachable via local EH edges is collected 4563 4) Eh tree is pruned for regions no longer necessary. 4564 4565 TODO: Push MUST_NOT_THROW regions to the root of the EH tree. 4566 Unify those that have the same failure decl and locus. 4567*/ 4568 4569static unsigned int 4570execute_cleanup_eh_1 (void) 4571{ 4572 /* Do this first: unsplit_all_eh and cleanup_all_empty_eh can die 4573 looking up unreachable landing pads. */ 4574 remove_unreachable_handlers (); 4575 4576 /* Watch out for the region tree vanishing due to all unreachable. */ 4577 if (cfun->eh->region_tree) 4578 { 4579 bool changed = false; 4580 4581 if (optimize) 4582 changed |= unsplit_all_eh (); 4583 changed |= cleanup_all_empty_eh (); 4584 4585 if (changed) 4586 { 4587 free_dominance_info (CDI_DOMINATORS); 4588 free_dominance_info (CDI_POST_DOMINATORS); 4589 4590 /* We delayed all basic block deletion, as we may have performed 4591 cleanups on EH edges while non-EH edges were still present. */ 4592 delete_unreachable_blocks (); 4593 4594 /* We manipulated the landing pads. Remove any region that no 4595 longer has a landing pad. */ 4596 remove_unreachable_handlers_no_lp (); 4597 4598 return TODO_cleanup_cfg | TODO_update_ssa_only_virtuals; 4599 } 4600 } 4601 4602 return 0; 4603} 4604 4605namespace { 4606 4607const pass_data pass_data_cleanup_eh = 4608{ 4609 GIMPLE_PASS, /* type */ 4610 "ehcleanup", /* name */ 4611 OPTGROUP_NONE, /* optinfo_flags */ 4612 TV_TREE_EH, /* tv_id */ 4613 PROP_gimple_lcf, /* properties_required */ 4614 0, /* properties_provided */ 4615 0, /* properties_destroyed */ 4616 0, /* todo_flags_start */ 4617 0, /* todo_flags_finish */ 4618}; 4619 4620class pass_cleanup_eh : public gimple_opt_pass 4621{ 4622public: 4623 pass_cleanup_eh (gcc::context *ctxt) 4624 : gimple_opt_pass (pass_data_cleanup_eh, ctxt) 4625 {} 4626 4627 /* opt_pass methods: */ 4628 opt_pass * clone () { return new pass_cleanup_eh (m_ctxt); } 4629 virtual bool gate (function *fun) 4630 { 4631 return fun->eh != NULL && fun->eh->region_tree != NULL; 4632 } 4633 4634 virtual unsigned int execute (function *); 4635 4636}; // class pass_cleanup_eh 4637 4638unsigned int 4639pass_cleanup_eh::execute (function *fun) 4640{ 4641 int ret = execute_cleanup_eh_1 (); 4642 4643 /* If the function no longer needs an EH personality routine 4644 clear it. This exposes cross-language inlining opportunities 4645 and avoids references to a never defined personality routine. */ 4646 if (DECL_FUNCTION_PERSONALITY (current_function_decl) 4647 && function_needs_eh_personality (fun) != eh_personality_lang) 4648 DECL_FUNCTION_PERSONALITY (current_function_decl) = NULL_TREE; 4649 4650 return ret; 4651} 4652 4653} // anon namespace 4654 4655gimple_opt_pass * 4656make_pass_cleanup_eh (gcc::context *ctxt) 4657{ 4658 return new pass_cleanup_eh (ctxt); 4659} 4660 4661/* Verify that BB containing STMT as the last statement, has precisely the 4662 edge that make_eh_edges would create. */ 4663 4664DEBUG_FUNCTION bool 4665verify_eh_edges (gimple stmt) 4666{ 4667 basic_block bb = gimple_bb (stmt); 4668 eh_landing_pad lp = NULL; 4669 int lp_nr; 4670 edge_iterator ei; 4671 edge e, eh_edge; 4672 4673 lp_nr = lookup_stmt_eh_lp (stmt); 4674 if (lp_nr > 0) 4675 lp = get_eh_landing_pad_from_number (lp_nr); 4676 4677 eh_edge = NULL; 4678 FOR_EACH_EDGE (e, ei, bb->succs) 4679 { 4680 if (e->flags & EDGE_EH) 4681 { 4682 if (eh_edge) 4683 { 4684 error ("BB %i has multiple EH edges", bb->index); 4685 return true; 4686 } 4687 else 4688 eh_edge = e; 4689 } 4690 } 4691 4692 if (lp == NULL) 4693 { 4694 if (eh_edge) 4695 { 4696 error ("BB %i can not throw but has an EH edge", bb->index); 4697 return true; 4698 } 4699 return false; 4700 } 4701 4702 if (!stmt_could_throw_p (stmt)) 4703 { 4704 error ("BB %i last statement has incorrectly set lp", bb->index); 4705 return true; 4706 } 4707 4708 if (eh_edge == NULL) 4709 { 4710 error ("BB %i is missing an EH edge", bb->index); 4711 return true; 4712 } 4713 4714 if (eh_edge->dest != label_to_block (lp->post_landing_pad)) 4715 { 4716 error ("Incorrect EH edge %i->%i", bb->index, eh_edge->dest->index); 4717 return true; 4718 } 4719 4720 return false; 4721} 4722 4723/* Similarly, but handle GIMPLE_EH_DISPATCH specifically. */ 4724 4725DEBUG_FUNCTION bool 4726verify_eh_dispatch_edge (geh_dispatch *stmt) 4727{ 4728 eh_region r; 4729 eh_catch c; 4730 basic_block src, dst; 4731 bool want_fallthru = true; 4732 edge_iterator ei; 4733 edge e, fall_edge; 4734 4735 r = get_eh_region_from_number (gimple_eh_dispatch_region (stmt)); 4736 src = gimple_bb (stmt); 4737 4738 FOR_EACH_EDGE (e, ei, src->succs) 4739 gcc_assert (e->aux == NULL); 4740 4741 switch (r->type) 4742 { 4743 case ERT_TRY: 4744 for (c = r->u.eh_try.first_catch; c ; c = c->next_catch) 4745 { 4746 dst = label_to_block (c->label); 4747 e = find_edge (src, dst); 4748 if (e == NULL) 4749 { 4750 error ("BB %i is missing an edge", src->index); 4751 return true; 4752 } 4753 e->aux = (void *)e; 4754 4755 /* A catch-all handler doesn't have a fallthru. */ 4756 if (c->type_list == NULL) 4757 { 4758 want_fallthru = false; 4759 break; 4760 } 4761 } 4762 break; 4763 4764 case ERT_ALLOWED_EXCEPTIONS: 4765 dst = label_to_block (r->u.allowed.label); 4766 e = find_edge (src, dst); 4767 if (e == NULL) 4768 { 4769 error ("BB %i is missing an edge", src->index); 4770 return true; 4771 } 4772 e->aux = (void *)e; 4773 break; 4774 4775 default: 4776 gcc_unreachable (); 4777 } 4778 4779 fall_edge = NULL; 4780 FOR_EACH_EDGE (e, ei, src->succs) 4781 { 4782 if (e->flags & EDGE_FALLTHRU) 4783 { 4784 if (fall_edge != NULL) 4785 { 4786 error ("BB %i too many fallthru edges", src->index); 4787 return true; 4788 } 4789 fall_edge = e; 4790 } 4791 else if (e->aux) 4792 e->aux = NULL; 4793 else 4794 { 4795 error ("BB %i has incorrect edge", src->index); 4796 return true; 4797 } 4798 } 4799 if ((fall_edge != NULL) ^ want_fallthru) 4800 { 4801 error ("BB %i has incorrect fallthru edge", src->index); 4802 return true; 4803 } 4804 4805 return false; 4806} 4807