1 /* Exception handling semantics and decomposition for trees. 2 Copyright (C) 2003-2018 Free Software Foundation, Inc. 3 4 This file is part of GCC. 5 6 GCC is free software; you can redistribute it and/or modify 7 it under the terms of the GNU General Public License as published by 8 the Free Software Foundation; either version 3, or (at your option) 9 any later version. 10 11 GCC is distributed in the hope that it will be useful, 12 but WITHOUT ANY WARRANTY; without even the implied warranty of 13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 GNU General Public License for more details. 15 16 You should have received a copy of the GNU General Public License 17 along 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 "backend.h" 24 #include "rtl.h" 25 #include "tree.h" 26 #include "gimple.h" 27 #include "cfghooks.h" 28 #include "tree-pass.h" 29 #include "ssa.h" 30 #include "cgraph.h" 31 #include "diagnostic-core.h" 32 #include "fold-const.h" 33 #include "calls.h" 34 #include "except.h" 35 #include "cfganal.h" 36 #include "cfgcleanup.h" 37 #include "tree-eh.h" 38 #include "gimple-iterator.h" 39 #include "tree-cfg.h" 40 #include "tree-into-ssa.h" 41 #include "tree-ssa.h" 42 #include "tree-inline.h" 43 #include "langhooks.h" 44 #include "cfgloop.h" 45 #include "gimple-low.h" 46 #include "stringpool.h" 47 #include "attribs.h" 48 #include "asan.h" 49 #include "gimplify.h" 50 51 /* In some instances a tree and a gimple need to be stored in a same table, 52 i.e. in hash tables. This is a structure to do this. */ 53 typedef union {tree *tp; tree t; gimple *g;} treemple; 54 55 /* Misc functions used in this file. */ 56 57 /* Remember and lookup EH landing pad data for arbitrary statements. 58 Really this means any statement that could_throw_p. We could 59 stuff this information into the stmt_ann data structure, but: 60 61 (1) We absolutely rely on this information being kept until 62 we get to rtl. Once we're done with lowering here, if we lose 63 the information there's no way to recover it! 64 65 (2) There are many more statements that *cannot* throw as 66 compared to those that can. We should be saving some amount 67 of space by only allocating memory for those that can throw. */ 68 69 /* Add statement T in function IFUN to landing pad NUM. */ 70 71 static void 72 add_stmt_to_eh_lp_fn (struct function *ifun, gimple *t, int num) 73 { 74 gcc_assert (num != 0); 75 76 if (!get_eh_throw_stmt_table (ifun)) 77 set_eh_throw_stmt_table (ifun, hash_map<gimple *, int>::create_ggc (31)); 78 79 gcc_assert (!get_eh_throw_stmt_table (ifun)->put (t, num)); 80 } 81 82 /* Add statement T in the current function (cfun) to EH landing pad NUM. */ 83 84 void 85 add_stmt_to_eh_lp (gimple *t, int num) 86 { 87 add_stmt_to_eh_lp_fn (cfun, t, num); 88 } 89 90 /* Add statement T to the single EH landing pad in REGION. */ 91 92 static void 93 record_stmt_eh_region (eh_region region, gimple *t) 94 { 95 if (region == NULL) 96 return; 97 if (region->type == ERT_MUST_NOT_THROW) 98 add_stmt_to_eh_lp_fn (cfun, t, -region->index); 99 else 100 { 101 eh_landing_pad lp = region->landing_pads; 102 if (lp == NULL) 103 lp = gen_eh_landing_pad (region); 104 else 105 gcc_assert (lp->next_lp == NULL); 106 add_stmt_to_eh_lp_fn (cfun, t, lp->index); 107 } 108 } 109 110 111 /* Remove statement T in function IFUN from its EH landing pad. */ 112 113 bool 114 remove_stmt_from_eh_lp_fn (struct function *ifun, gimple *t) 115 { 116 if (!get_eh_throw_stmt_table (ifun)) 117 return false; 118 119 if (!get_eh_throw_stmt_table (ifun)->get (t)) 120 return false; 121 122 get_eh_throw_stmt_table (ifun)->remove (t); 123 return true; 124 } 125 126 127 /* Remove statement T in the current function (cfun) from its 128 EH landing pad. */ 129 130 bool 131 remove_stmt_from_eh_lp (gimple *t) 132 { 133 return remove_stmt_from_eh_lp_fn (cfun, t); 134 } 135 136 /* Determine if statement T is inside an EH region in function IFUN. 137 Positive numbers indicate a landing pad index; negative numbers 138 indicate a MUST_NOT_THROW region index; zero indicates that the 139 statement is not recorded in the region table. */ 140 141 int 142 lookup_stmt_eh_lp_fn (struct function *ifun, gimple *t) 143 { 144 if (ifun->eh->throw_stmt_table == NULL) 145 return 0; 146 147 int *lp_nr = ifun->eh->throw_stmt_table->get (t); 148 return lp_nr ? *lp_nr : 0; 149 } 150 151 /* Likewise, but always use the current function. */ 152 153 int 154 lookup_stmt_eh_lp (gimple *t) 155 { 156 /* We can get called from initialized data when -fnon-call-exceptions 157 is on; prevent crash. */ 158 if (!cfun) 159 return 0; 160 return lookup_stmt_eh_lp_fn (cfun, t); 161 } 162 163 /* First pass of EH node decomposition. Build up a tree of GIMPLE_TRY_FINALLY 164 nodes and LABEL_DECL nodes. We will use this during the second phase to 165 determine if a goto leaves the body of a TRY_FINALLY_EXPR node. */ 166 167 struct finally_tree_node 168 { 169 /* When storing a GIMPLE_TRY, we have to record a gimple. However 170 when deciding whether a GOTO to a certain LABEL_DECL (which is a 171 tree) leaves the TRY block, its necessary to record a tree in 172 this field. Thus a treemple is used. */ 173 treemple child; 174 gtry *parent; 175 }; 176 177 /* Hashtable helpers. */ 178 179 struct finally_tree_hasher : free_ptr_hash <finally_tree_node> 180 { 181 static inline hashval_t hash (const finally_tree_node *); 182 static inline bool equal (const finally_tree_node *, 183 const finally_tree_node *); 184 }; 185 186 inline hashval_t 187 finally_tree_hasher::hash (const finally_tree_node *v) 188 { 189 return (intptr_t)v->child.t >> 4; 190 } 191 192 inline bool 193 finally_tree_hasher::equal (const finally_tree_node *v, 194 const finally_tree_node *c) 195 { 196 return v->child.t == c->child.t; 197 } 198 199 /* Note that this table is *not* marked GTY. It is short-lived. */ 200 static hash_table<finally_tree_hasher> *finally_tree; 201 202 static void 203 record_in_finally_tree (treemple child, gtry *parent) 204 { 205 struct finally_tree_node *n; 206 finally_tree_node **slot; 207 208 n = XNEW (struct finally_tree_node); 209 n->child = child; 210 n->parent = parent; 211 212 slot = finally_tree->find_slot (n, INSERT); 213 gcc_assert (!*slot); 214 *slot = n; 215 } 216 217 static void 218 collect_finally_tree (gimple *stmt, gtry *region); 219 220 /* Go through the gimple sequence. Works with collect_finally_tree to 221 record all GIMPLE_LABEL and GIMPLE_TRY statements. */ 222 223 static void 224 collect_finally_tree_1 (gimple_seq seq, gtry *region) 225 { 226 gimple_stmt_iterator gsi; 227 228 for (gsi = gsi_start (seq); !gsi_end_p (gsi); gsi_next (&gsi)) 229 collect_finally_tree (gsi_stmt (gsi), region); 230 } 231 232 static void 233 collect_finally_tree (gimple *stmt, gtry *region) 234 { 235 treemple temp; 236 237 switch (gimple_code (stmt)) 238 { 239 case GIMPLE_LABEL: 240 temp.t = gimple_label_label (as_a <glabel *> (stmt)); 241 record_in_finally_tree (temp, region); 242 break; 243 244 case GIMPLE_TRY: 245 if (gimple_try_kind (stmt) == GIMPLE_TRY_FINALLY) 246 { 247 temp.g = stmt; 248 record_in_finally_tree (temp, region); 249 collect_finally_tree_1 (gimple_try_eval (stmt), 250 as_a <gtry *> (stmt)); 251 collect_finally_tree_1 (gimple_try_cleanup (stmt), region); 252 } 253 else if (gimple_try_kind (stmt) == GIMPLE_TRY_CATCH) 254 { 255 collect_finally_tree_1 (gimple_try_eval (stmt), region); 256 collect_finally_tree_1 (gimple_try_cleanup (stmt), region); 257 } 258 break; 259 260 case GIMPLE_CATCH: 261 collect_finally_tree_1 (gimple_catch_handler ( 262 as_a <gcatch *> (stmt)), 263 region); 264 break; 265 266 case GIMPLE_EH_FILTER: 267 collect_finally_tree_1 (gimple_eh_filter_failure (stmt), region); 268 break; 269 270 case GIMPLE_EH_ELSE: 271 { 272 geh_else *eh_else_stmt = as_a <geh_else *> (stmt); 273 collect_finally_tree_1 (gimple_eh_else_n_body (eh_else_stmt), region); 274 collect_finally_tree_1 (gimple_eh_else_e_body (eh_else_stmt), region); 275 } 276 break; 277 278 default: 279 /* A type, a decl, or some kind of statement that we're not 280 interested in. Don't walk them. */ 281 break; 282 } 283 } 284 285 286 /* Use the finally tree to determine if a jump from START to TARGET 287 would leave the try_finally node that START lives in. */ 288 289 static bool 290 outside_finally_tree (treemple start, gimple *target) 291 { 292 struct finally_tree_node n, *p; 293 294 do 295 { 296 n.child = start; 297 p = finally_tree->find (&n); 298 if (!p) 299 return true; 300 start.g = p->parent; 301 } 302 while (start.g != target); 303 304 return false; 305 } 306 307 /* Second pass of EH node decomposition. Actually transform the GIMPLE_TRY 308 nodes into a set of gotos, magic labels, and eh regions. 309 The eh region creation is straight-forward, but frobbing all the gotos 310 and such into shape isn't. */ 311 312 /* The sequence into which we record all EH stuff. This will be 313 placed at the end of the function when we're all done. */ 314 static gimple_seq eh_seq; 315 316 /* Record whether an EH region contains something that can throw, 317 indexed by EH region number. */ 318 static bitmap eh_region_may_contain_throw_map; 319 320 /* The GOTO_QUEUE is an array of GIMPLE_GOTO and GIMPLE_RETURN 321 statements that are seen to escape this GIMPLE_TRY_FINALLY node. 322 The idea is to record a gimple statement for everything except for 323 the conditionals, which get their labels recorded. Since labels are 324 of type 'tree', we need this node to store both gimple and tree 325 objects. REPL_STMT is the sequence used to replace the goto/return 326 statement. CONT_STMT is used to store the statement that allows 327 the return/goto to jump to the original destination. */ 328 329 struct goto_queue_node 330 { 331 treemple stmt; 332 location_t location; 333 gimple_seq repl_stmt; 334 gimple *cont_stmt; 335 int index; 336 /* This is used when index >= 0 to indicate that stmt is a label (as 337 opposed to a goto stmt). */ 338 int is_label; 339 }; 340 341 /* State of the world while lowering. */ 342 343 struct leh_state 344 { 345 /* What's "current" while constructing the eh region tree. These 346 correspond to variables of the same name in cfun->eh, which we 347 don't have easy access to. */ 348 eh_region cur_region; 349 350 /* What's "current" for the purposes of __builtin_eh_pointer. For 351 a CATCH, this is the associated TRY. For an EH_FILTER, this is 352 the associated ALLOWED_EXCEPTIONS, etc. */ 353 eh_region ehp_region; 354 355 /* Processing of TRY_FINALLY requires a bit more state. This is 356 split out into a separate structure so that we don't have to 357 copy so much when processing other nodes. */ 358 struct leh_tf_state *tf; 359 }; 360 361 struct leh_tf_state 362 { 363 /* Pointer to the GIMPLE_TRY_FINALLY node under discussion. The 364 try_finally_expr is the original GIMPLE_TRY_FINALLY. We need to retain 365 this so that outside_finally_tree can reliably reference the tree used 366 in the collect_finally_tree data structures. */ 367 gtry *try_finally_expr; 368 gtry *top_p; 369 370 /* While lowering a top_p usually it is expanded into multiple statements, 371 thus we need the following field to store them. */ 372 gimple_seq top_p_seq; 373 374 /* The state outside this try_finally node. */ 375 struct leh_state *outer; 376 377 /* The exception region created for it. */ 378 eh_region region; 379 380 /* The goto queue. */ 381 struct goto_queue_node *goto_queue; 382 size_t goto_queue_size; 383 size_t goto_queue_active; 384 385 /* Pointer map to help in searching goto_queue when it is large. */ 386 hash_map<gimple *, goto_queue_node *> *goto_queue_map; 387 388 /* The set of unique labels seen as entries in the goto queue. */ 389 vec<tree> dest_array; 390 391 /* A label to be added at the end of the completed transformed 392 sequence. It will be set if may_fallthru was true *at one time*, 393 though subsequent transformations may have cleared that flag. */ 394 tree fallthru_label; 395 396 /* True if it is possible to fall out the bottom of the try block. 397 Cleared if the fallthru is converted to a goto. */ 398 bool may_fallthru; 399 400 /* True if any entry in goto_queue is a GIMPLE_RETURN. */ 401 bool may_return; 402 403 /* True if the finally block can receive an exception edge. 404 Cleared if the exception case is handled by code duplication. */ 405 bool may_throw; 406 }; 407 408 static gimple_seq lower_eh_must_not_throw (struct leh_state *, gtry *); 409 410 /* Search for STMT in the goto queue. Return the replacement, 411 or null if the statement isn't in the queue. */ 412 413 #define LARGE_GOTO_QUEUE 20 414 415 static void lower_eh_constructs_1 (struct leh_state *state, gimple_seq *seq); 416 417 static gimple_seq 418 find_goto_replacement (struct leh_tf_state *tf, treemple stmt) 419 { 420 unsigned int i; 421 422 if (tf->goto_queue_active < LARGE_GOTO_QUEUE) 423 { 424 for (i = 0; i < tf->goto_queue_active; i++) 425 if ( tf->goto_queue[i].stmt.g == stmt.g) 426 return tf->goto_queue[i].repl_stmt; 427 return NULL; 428 } 429 430 /* If we have a large number of entries in the goto_queue, create a 431 pointer map and use that for searching. */ 432 433 if (!tf->goto_queue_map) 434 { 435 tf->goto_queue_map = new hash_map<gimple *, goto_queue_node *>; 436 for (i = 0; i < tf->goto_queue_active; i++) 437 { 438 bool existed = tf->goto_queue_map->put (tf->goto_queue[i].stmt.g, 439 &tf->goto_queue[i]); 440 gcc_assert (!existed); 441 } 442 } 443 444 goto_queue_node **slot = tf->goto_queue_map->get (stmt.g); 445 if (slot != NULL) 446 return ((*slot)->repl_stmt); 447 448 return NULL; 449 } 450 451 /* A subroutine of replace_goto_queue_1. Handles the sub-clauses of a 452 lowered GIMPLE_COND. If, by chance, the replacement is a simple goto, 453 then we can just splat it in, otherwise we add the new stmts immediately 454 after the GIMPLE_COND and redirect. */ 455 456 static void 457 replace_goto_queue_cond_clause (tree *tp, struct leh_tf_state *tf, 458 gimple_stmt_iterator *gsi) 459 { 460 tree label; 461 gimple_seq new_seq; 462 treemple temp; 463 location_t loc = gimple_location (gsi_stmt (*gsi)); 464 465 temp.tp = tp; 466 new_seq = find_goto_replacement (tf, temp); 467 if (!new_seq) 468 return; 469 470 if (gimple_seq_singleton_p (new_seq) 471 && gimple_code (gimple_seq_first_stmt (new_seq)) == GIMPLE_GOTO) 472 { 473 *tp = gimple_goto_dest (gimple_seq_first_stmt (new_seq)); 474 return; 475 } 476 477 label = create_artificial_label (loc); 478 /* Set the new label for the GIMPLE_COND */ 479 *tp = label; 480 481 gsi_insert_after (gsi, gimple_build_label (label), GSI_CONTINUE_LINKING); 482 gsi_insert_seq_after (gsi, gimple_seq_copy (new_seq), GSI_CONTINUE_LINKING); 483 } 484 485 /* The real work of replace_goto_queue. Returns with TSI updated to 486 point to the next statement. */ 487 488 static void replace_goto_queue_stmt_list (gimple_seq *, struct leh_tf_state *); 489 490 static void 491 replace_goto_queue_1 (gimple *stmt, struct leh_tf_state *tf, 492 gimple_stmt_iterator *gsi) 493 { 494 gimple_seq seq; 495 treemple temp; 496 temp.g = NULL; 497 498 switch (gimple_code (stmt)) 499 { 500 case GIMPLE_GOTO: 501 case GIMPLE_RETURN: 502 temp.g = stmt; 503 seq = find_goto_replacement (tf, temp); 504 if (seq) 505 { 506 gsi_insert_seq_before (gsi, gimple_seq_copy (seq), GSI_SAME_STMT); 507 gsi_remove (gsi, false); 508 return; 509 } 510 break; 511 512 case GIMPLE_COND: 513 replace_goto_queue_cond_clause (gimple_op_ptr (stmt, 2), tf, gsi); 514 replace_goto_queue_cond_clause (gimple_op_ptr (stmt, 3), tf, gsi); 515 break; 516 517 case GIMPLE_TRY: 518 replace_goto_queue_stmt_list (gimple_try_eval_ptr (stmt), tf); 519 replace_goto_queue_stmt_list (gimple_try_cleanup_ptr (stmt), tf); 520 break; 521 case GIMPLE_CATCH: 522 replace_goto_queue_stmt_list (gimple_catch_handler_ptr ( 523 as_a <gcatch *> (stmt)), 524 tf); 525 break; 526 case GIMPLE_EH_FILTER: 527 replace_goto_queue_stmt_list (gimple_eh_filter_failure_ptr (stmt), tf); 528 break; 529 case GIMPLE_EH_ELSE: 530 { 531 geh_else *eh_else_stmt = as_a <geh_else *> (stmt); 532 replace_goto_queue_stmt_list (gimple_eh_else_n_body_ptr (eh_else_stmt), 533 tf); 534 replace_goto_queue_stmt_list (gimple_eh_else_e_body_ptr (eh_else_stmt), 535 tf); 536 } 537 break; 538 539 default: 540 /* These won't have gotos in them. */ 541 break; 542 } 543 544 gsi_next (gsi); 545 } 546 547 /* A subroutine of replace_goto_queue. Handles GIMPLE_SEQ. */ 548 549 static void 550 replace_goto_queue_stmt_list (gimple_seq *seq, struct leh_tf_state *tf) 551 { 552 gimple_stmt_iterator gsi = gsi_start (*seq); 553 554 while (!gsi_end_p (gsi)) 555 replace_goto_queue_1 (gsi_stmt (gsi), tf, &gsi); 556 } 557 558 /* Replace all goto queue members. */ 559 560 static void 561 replace_goto_queue (struct leh_tf_state *tf) 562 { 563 if (tf->goto_queue_active == 0) 564 return; 565 replace_goto_queue_stmt_list (&tf->top_p_seq, tf); 566 replace_goto_queue_stmt_list (&eh_seq, tf); 567 } 568 569 /* Add a new record to the goto queue contained in TF. NEW_STMT is the 570 data to be added, IS_LABEL indicates whether NEW_STMT is a label or 571 a gimple return. */ 572 573 static void 574 record_in_goto_queue (struct leh_tf_state *tf, 575 treemple new_stmt, 576 int index, 577 bool is_label, 578 location_t location) 579 { 580 size_t active, size; 581 struct goto_queue_node *q; 582 583 gcc_assert (!tf->goto_queue_map); 584 585 active = tf->goto_queue_active; 586 size = tf->goto_queue_size; 587 if (active >= size) 588 { 589 size = (size ? size * 2 : 32); 590 tf->goto_queue_size = size; 591 tf->goto_queue 592 = XRESIZEVEC (struct goto_queue_node, tf->goto_queue, size); 593 } 594 595 q = &tf->goto_queue[active]; 596 tf->goto_queue_active = active + 1; 597 598 memset (q, 0, sizeof (*q)); 599 q->stmt = new_stmt; 600 q->index = index; 601 q->location = location; 602 q->is_label = is_label; 603 } 604 605 /* Record the LABEL label in the goto queue contained in TF. 606 TF is not null. */ 607 608 static void 609 record_in_goto_queue_label (struct leh_tf_state *tf, treemple stmt, tree label, 610 location_t location) 611 { 612 int index; 613 treemple temp, new_stmt; 614 615 if (!label) 616 return; 617 618 /* Computed and non-local gotos do not get processed. Given 619 their nature we can neither tell whether we've escaped the 620 finally block nor redirect them if we knew. */ 621 if (TREE_CODE (label) != LABEL_DECL) 622 return; 623 624 /* No need to record gotos that don't leave the try block. */ 625 temp.t = label; 626 if (!outside_finally_tree (temp, tf->try_finally_expr)) 627 return; 628 629 if (! tf->dest_array.exists ()) 630 { 631 tf->dest_array.create (10); 632 tf->dest_array.quick_push (label); 633 index = 0; 634 } 635 else 636 { 637 int n = tf->dest_array.length (); 638 for (index = 0; index < n; ++index) 639 if (tf->dest_array[index] == label) 640 break; 641 if (index == n) 642 tf->dest_array.safe_push (label); 643 } 644 645 /* In the case of a GOTO we want to record the destination label, 646 since with a GIMPLE_COND we have an easy access to the then/else 647 labels. */ 648 new_stmt = stmt; 649 record_in_goto_queue (tf, new_stmt, index, true, location); 650 } 651 652 /* For any GIMPLE_GOTO or GIMPLE_RETURN, decide whether it leaves a try_finally 653 node, and if so record that fact in the goto queue associated with that 654 try_finally node. */ 655 656 static void 657 maybe_record_in_goto_queue (struct leh_state *state, gimple *stmt) 658 { 659 struct leh_tf_state *tf = state->tf; 660 treemple new_stmt; 661 662 if (!tf) 663 return; 664 665 switch (gimple_code (stmt)) 666 { 667 case GIMPLE_COND: 668 { 669 gcond *cond_stmt = as_a <gcond *> (stmt); 670 new_stmt.tp = gimple_op_ptr (cond_stmt, 2); 671 record_in_goto_queue_label (tf, new_stmt, 672 gimple_cond_true_label (cond_stmt), 673 EXPR_LOCATION (*new_stmt.tp)); 674 new_stmt.tp = gimple_op_ptr (cond_stmt, 3); 675 record_in_goto_queue_label (tf, new_stmt, 676 gimple_cond_false_label (cond_stmt), 677 EXPR_LOCATION (*new_stmt.tp)); 678 } 679 break; 680 case GIMPLE_GOTO: 681 new_stmt.g = stmt; 682 record_in_goto_queue_label (tf, new_stmt, gimple_goto_dest (stmt), 683 gimple_location (stmt)); 684 break; 685 686 case GIMPLE_RETURN: 687 tf->may_return = true; 688 new_stmt.g = stmt; 689 record_in_goto_queue (tf, new_stmt, -1, false, gimple_location (stmt)); 690 break; 691 692 default: 693 gcc_unreachable (); 694 } 695 } 696 697 698 #if CHECKING_P 699 /* We do not process GIMPLE_SWITCHes for now. As long as the original source 700 was in fact structured, and we've not yet done jump threading, then none 701 of the labels will leave outer GIMPLE_TRY_FINALLY nodes. Verify this. */ 702 703 static void 704 verify_norecord_switch_expr (struct leh_state *state, 705 gswitch *switch_expr) 706 { 707 struct leh_tf_state *tf = state->tf; 708 size_t i, n; 709 710 if (!tf) 711 return; 712 713 n = gimple_switch_num_labels (switch_expr); 714 715 for (i = 0; i < n; ++i) 716 { 717 treemple temp; 718 tree lab = CASE_LABEL (gimple_switch_label (switch_expr, i)); 719 temp.t = lab; 720 gcc_assert (!outside_finally_tree (temp, tf->try_finally_expr)); 721 } 722 } 723 #else 724 #define verify_norecord_switch_expr(state, switch_expr) 725 #endif 726 727 /* Redirect a RETURN_EXPR pointed to by Q to FINLAB. If MOD is 728 non-null, insert it before the new branch. */ 729 730 static void 731 do_return_redirection (struct goto_queue_node *q, tree finlab, gimple_seq mod) 732 { 733 gimple *x; 734 735 /* In the case of a return, the queue node must be a gimple statement. */ 736 gcc_assert (!q->is_label); 737 738 /* Note that the return value may have already been computed, e.g., 739 740 int x; 741 int foo (void) 742 { 743 x = 0; 744 try { 745 return x; 746 } finally { 747 x++; 748 } 749 } 750 751 should return 0, not 1. We don't have to do anything to make 752 this happens because the return value has been placed in the 753 RESULT_DECL already. */ 754 755 q->cont_stmt = q->stmt.g; 756 757 if (mod) 758 gimple_seq_add_seq (&q->repl_stmt, mod); 759 760 x = gimple_build_goto (finlab); 761 gimple_set_location (x, q->location); 762 gimple_seq_add_stmt (&q->repl_stmt, x); 763 } 764 765 /* Similar, but easier, for GIMPLE_GOTO. */ 766 767 static void 768 do_goto_redirection (struct goto_queue_node *q, tree finlab, gimple_seq mod, 769 struct leh_tf_state *tf) 770 { 771 ggoto *x; 772 773 gcc_assert (q->is_label); 774 775 q->cont_stmt = gimple_build_goto (tf->dest_array[q->index]); 776 777 if (mod) 778 gimple_seq_add_seq (&q->repl_stmt, mod); 779 780 x = gimple_build_goto (finlab); 781 gimple_set_location (x, q->location); 782 gimple_seq_add_stmt (&q->repl_stmt, x); 783 } 784 785 /* Emit a standard landing pad sequence into SEQ for REGION. */ 786 787 static void 788 emit_post_landing_pad (gimple_seq *seq, eh_region region) 789 { 790 eh_landing_pad lp = region->landing_pads; 791 glabel *x; 792 793 if (lp == NULL) 794 lp = gen_eh_landing_pad (region); 795 796 lp->post_landing_pad = create_artificial_label (UNKNOWN_LOCATION); 797 EH_LANDING_PAD_NR (lp->post_landing_pad) = lp->index; 798 799 x = gimple_build_label (lp->post_landing_pad); 800 gimple_seq_add_stmt (seq, x); 801 } 802 803 /* Emit a RESX statement into SEQ for REGION. */ 804 805 static void 806 emit_resx (gimple_seq *seq, eh_region region) 807 { 808 gresx *x = gimple_build_resx (region->index); 809 gimple_seq_add_stmt (seq, x); 810 if (region->outer) 811 record_stmt_eh_region (region->outer, x); 812 } 813 814 /* Emit an EH_DISPATCH statement into SEQ for REGION. */ 815 816 static void 817 emit_eh_dispatch (gimple_seq *seq, eh_region region) 818 { 819 geh_dispatch *x = gimple_build_eh_dispatch (region->index); 820 gimple_seq_add_stmt (seq, x); 821 } 822 823 /* Note that the current EH region may contain a throw, or a 824 call to a function which itself may contain a throw. */ 825 826 static void 827 note_eh_region_may_contain_throw (eh_region region) 828 { 829 while (bitmap_set_bit (eh_region_may_contain_throw_map, region->index)) 830 { 831 if (region->type == ERT_MUST_NOT_THROW) 832 break; 833 region = region->outer; 834 if (region == NULL) 835 break; 836 } 837 } 838 839 /* Check if REGION has been marked as containing a throw. If REGION is 840 NULL, this predicate is false. */ 841 842 static inline bool 843 eh_region_may_contain_throw (eh_region r) 844 { 845 return r && bitmap_bit_p (eh_region_may_contain_throw_map, r->index); 846 } 847 848 /* We want to transform 849 try { body; } catch { stuff; } 850 to 851 normal_sequence: 852 body; 853 over: 854 eh_sequence: 855 landing_pad: 856 stuff; 857 goto over; 858 859 TP is a GIMPLE_TRY node. REGION is the region whose post_landing_pad 860 should be placed before the second operand, or NULL. OVER is 861 an existing label that should be put at the exit, or NULL. */ 862 863 static gimple_seq 864 frob_into_branch_around (gtry *tp, eh_region region, tree over) 865 { 866 gimple *x; 867 gimple_seq cleanup, result; 868 location_t loc = gimple_location (tp); 869 870 cleanup = gimple_try_cleanup (tp); 871 result = gimple_try_eval (tp); 872 873 if (region) 874 emit_post_landing_pad (&eh_seq, region); 875 876 if (gimple_seq_may_fallthru (cleanup)) 877 { 878 if (!over) 879 over = create_artificial_label (loc); 880 x = gimple_build_goto (over); 881 gimple_set_location (x, loc); 882 gimple_seq_add_stmt (&cleanup, x); 883 } 884 gimple_seq_add_seq (&eh_seq, cleanup); 885 886 if (over) 887 { 888 x = gimple_build_label (over); 889 gimple_seq_add_stmt (&result, x); 890 } 891 return result; 892 } 893 894 /* A subroutine of lower_try_finally. Duplicate the tree rooted at T. 895 Make sure to record all new labels found. */ 896 897 static gimple_seq 898 lower_try_finally_dup_block (gimple_seq seq, struct leh_state *outer_state, 899 location_t loc) 900 { 901 gtry *region = NULL; 902 gimple_seq new_seq; 903 gimple_stmt_iterator gsi; 904 905 new_seq = copy_gimple_seq_and_replace_locals (seq); 906 907 for (gsi = gsi_start (new_seq); !gsi_end_p (gsi); gsi_next (&gsi)) 908 { 909 gimple *stmt = gsi_stmt (gsi); 910 /* We duplicate __builtin_stack_restore at -O0 in the hope of eliminating 911 it on the EH paths. When it is not eliminated, make it transparent in 912 the debug info. */ 913 if (gimple_call_builtin_p (stmt, BUILT_IN_STACK_RESTORE)) 914 gimple_set_location (stmt, UNKNOWN_LOCATION); 915 else if (LOCATION_LOCUS (gimple_location (stmt)) == UNKNOWN_LOCATION) 916 { 917 tree block = gimple_block (stmt); 918 gimple_set_location (stmt, loc); 919 gimple_set_block (stmt, block); 920 } 921 } 922 923 if (outer_state->tf) 924 region = outer_state->tf->try_finally_expr; 925 collect_finally_tree_1 (new_seq, region); 926 927 return new_seq; 928 } 929 930 /* A subroutine of lower_try_finally. Create a fallthru label for 931 the given try_finally state. The only tricky bit here is that 932 we have to make sure to record the label in our outer context. */ 933 934 static tree 935 lower_try_finally_fallthru_label (struct leh_tf_state *tf) 936 { 937 tree label = tf->fallthru_label; 938 treemple temp; 939 940 if (!label) 941 { 942 label = create_artificial_label (gimple_location (tf->try_finally_expr)); 943 tf->fallthru_label = label; 944 if (tf->outer->tf) 945 { 946 temp.t = label; 947 record_in_finally_tree (temp, tf->outer->tf->try_finally_expr); 948 } 949 } 950 return label; 951 } 952 953 /* A subroutine of lower_try_finally. If FINALLY consits of a 954 GIMPLE_EH_ELSE node, return it. */ 955 956 static inline geh_else * 957 get_eh_else (gimple_seq finally) 958 { 959 gimple *x = gimple_seq_first_stmt (finally); 960 if (gimple_code (x) == GIMPLE_EH_ELSE) 961 { 962 gcc_assert (gimple_seq_singleton_p (finally)); 963 return as_a <geh_else *> (x); 964 } 965 return NULL; 966 } 967 968 /* A subroutine of lower_try_finally. If the eh_protect_cleanup_actions 969 langhook returns non-null, then the language requires that the exception 970 path out of a try_finally be treated specially. To wit: the code within 971 the finally block may not itself throw an exception. We have two choices 972 here. First we can duplicate the finally block and wrap it in a 973 must_not_throw region. Second, we can generate code like 974 975 try { 976 finally_block; 977 } catch { 978 if (fintmp == eh_edge) 979 protect_cleanup_actions; 980 } 981 982 where "fintmp" is the temporary used in the switch statement generation 983 alternative considered below. For the nonce, we always choose the first 984 option. 985 986 THIS_STATE may be null if this is a try-cleanup, not a try-finally. */ 987 988 static void 989 honor_protect_cleanup_actions (struct leh_state *outer_state, 990 struct leh_state *this_state, 991 struct leh_tf_state *tf) 992 { 993 gimple_seq finally = gimple_try_cleanup (tf->top_p); 994 995 /* EH_ELSE doesn't come from user code; only compiler generated stuff. 996 It does need to be handled here, so as to separate the (different) 997 EH path from the normal path. But we should not attempt to wrap 998 it with a must-not-throw node (which indeed gets in the way). */ 999 if (geh_else *eh_else = get_eh_else (finally)) 1000 { 1001 gimple_try_set_cleanup (tf->top_p, gimple_eh_else_n_body (eh_else)); 1002 finally = gimple_eh_else_e_body (eh_else); 1003 1004 /* Let the ELSE see the exception that's being processed. */ 1005 eh_region save_ehp = this_state->ehp_region; 1006 this_state->ehp_region = this_state->cur_region; 1007 lower_eh_constructs_1 (this_state, &finally); 1008 this_state->ehp_region = save_ehp; 1009 } 1010 else 1011 { 1012 /* First check for nothing to do. */ 1013 if (lang_hooks.eh_protect_cleanup_actions == NULL) 1014 return; 1015 tree actions = lang_hooks.eh_protect_cleanup_actions (); 1016 if (actions == NULL) 1017 return; 1018 1019 if (this_state) 1020 finally = lower_try_finally_dup_block (finally, outer_state, 1021 gimple_location (tf->try_finally_expr)); 1022 1023 /* If this cleanup consists of a TRY_CATCH_EXPR with TRY_CATCH_IS_CLEANUP 1024 set, the handler of the TRY_CATCH_EXPR is another cleanup which ought 1025 to be in an enclosing scope, but needs to be implemented at this level 1026 to avoid a nesting violation (see wrap_temporary_cleanups in 1027 cp/decl.c). Since it's logically at an outer level, we should call 1028 terminate before we get to it, so strip it away before adding the 1029 MUST_NOT_THROW filter. */ 1030 gimple_stmt_iterator gsi = gsi_start (finally); 1031 gimple *x = gsi_stmt (gsi); 1032 if (gimple_code (x) == GIMPLE_TRY 1033 && gimple_try_kind (x) == GIMPLE_TRY_CATCH 1034 && gimple_try_catch_is_cleanup (x)) 1035 { 1036 gsi_insert_seq_before (&gsi, gimple_try_eval (x), GSI_SAME_STMT); 1037 gsi_remove (&gsi, false); 1038 } 1039 1040 /* Wrap the block with protect_cleanup_actions as the action. */ 1041 geh_mnt *eh_mnt = gimple_build_eh_must_not_throw (actions); 1042 gtry *try_stmt = gimple_build_try (finally, 1043 gimple_seq_alloc_with_stmt (eh_mnt), 1044 GIMPLE_TRY_CATCH); 1045 finally = lower_eh_must_not_throw (outer_state, try_stmt); 1046 } 1047 1048 /* Drop all of this into the exception sequence. */ 1049 emit_post_landing_pad (&eh_seq, tf->region); 1050 gimple_seq_add_seq (&eh_seq, finally); 1051 if (gimple_seq_may_fallthru (finally)) 1052 emit_resx (&eh_seq, tf->region); 1053 1054 /* Having now been handled, EH isn't to be considered with 1055 the rest of the outgoing edges. */ 1056 tf->may_throw = false; 1057 } 1058 1059 /* A subroutine of lower_try_finally. We have determined that there is 1060 no fallthru edge out of the finally block. This means that there is 1061 no outgoing edge corresponding to any incoming edge. Restructure the 1062 try_finally node for this special case. */ 1063 1064 static void 1065 lower_try_finally_nofallthru (struct leh_state *state, 1066 struct leh_tf_state *tf) 1067 { 1068 tree lab; 1069 gimple *x; 1070 geh_else *eh_else; 1071 gimple_seq finally; 1072 struct goto_queue_node *q, *qe; 1073 1074 lab = create_artificial_label (gimple_location (tf->try_finally_expr)); 1075 1076 /* We expect that tf->top_p is a GIMPLE_TRY. */ 1077 finally = gimple_try_cleanup (tf->top_p); 1078 tf->top_p_seq = gimple_try_eval (tf->top_p); 1079 1080 x = gimple_build_label (lab); 1081 gimple_seq_add_stmt (&tf->top_p_seq, x); 1082 1083 q = tf->goto_queue; 1084 qe = q + tf->goto_queue_active; 1085 for (; q < qe; ++q) 1086 if (q->index < 0) 1087 do_return_redirection (q, lab, NULL); 1088 else 1089 do_goto_redirection (q, lab, NULL, tf); 1090 1091 replace_goto_queue (tf); 1092 1093 /* Emit the finally block into the stream. Lower EH_ELSE at this time. */ 1094 eh_else = get_eh_else (finally); 1095 if (eh_else) 1096 { 1097 finally = gimple_eh_else_n_body (eh_else); 1098 lower_eh_constructs_1 (state, &finally); 1099 gimple_seq_add_seq (&tf->top_p_seq, finally); 1100 1101 if (tf->may_throw) 1102 { 1103 finally = gimple_eh_else_e_body (eh_else); 1104 lower_eh_constructs_1 (state, &finally); 1105 1106 emit_post_landing_pad (&eh_seq, tf->region); 1107 gimple_seq_add_seq (&eh_seq, finally); 1108 } 1109 } 1110 else 1111 { 1112 lower_eh_constructs_1 (state, &finally); 1113 gimple_seq_add_seq (&tf->top_p_seq, finally); 1114 1115 if (tf->may_throw) 1116 { 1117 emit_post_landing_pad (&eh_seq, tf->region); 1118 1119 x = gimple_build_goto (lab); 1120 gimple_set_location (x, gimple_location (tf->try_finally_expr)); 1121 gimple_seq_add_stmt (&eh_seq, x); 1122 } 1123 } 1124 } 1125 1126 /* A subroutine of lower_try_finally. We have determined that there is 1127 exactly one destination of the finally block. Restructure the 1128 try_finally node for this special case. */ 1129 1130 static void 1131 lower_try_finally_onedest (struct leh_state *state, struct leh_tf_state *tf) 1132 { 1133 struct goto_queue_node *q, *qe; 1134 geh_else *eh_else; 1135 glabel *label_stmt; 1136 gimple *x; 1137 gimple_seq finally; 1138 gimple_stmt_iterator gsi; 1139 tree finally_label; 1140 location_t loc = gimple_location (tf->try_finally_expr); 1141 1142 finally = gimple_try_cleanup (tf->top_p); 1143 tf->top_p_seq = gimple_try_eval (tf->top_p); 1144 1145 /* Since there's only one destination, and the destination edge can only 1146 either be EH or non-EH, that implies that all of our incoming edges 1147 are of the same type. Therefore we can lower EH_ELSE immediately. */ 1148 eh_else = get_eh_else (finally); 1149 if (eh_else) 1150 { 1151 if (tf->may_throw) 1152 finally = gimple_eh_else_e_body (eh_else); 1153 else 1154 finally = gimple_eh_else_n_body (eh_else); 1155 } 1156 1157 lower_eh_constructs_1 (state, &finally); 1158 1159 for (gsi = gsi_start (finally); !gsi_end_p (gsi); gsi_next (&gsi)) 1160 { 1161 gimple *stmt = gsi_stmt (gsi); 1162 if (LOCATION_LOCUS (gimple_location (stmt)) == UNKNOWN_LOCATION) 1163 { 1164 tree block = gimple_block (stmt); 1165 gimple_set_location (stmt, gimple_location (tf->try_finally_expr)); 1166 gimple_set_block (stmt, block); 1167 } 1168 } 1169 1170 if (tf->may_throw) 1171 { 1172 /* Only reachable via the exception edge. Add the given label to 1173 the head of the FINALLY block. Append a RESX at the end. */ 1174 emit_post_landing_pad (&eh_seq, tf->region); 1175 gimple_seq_add_seq (&eh_seq, finally); 1176 emit_resx (&eh_seq, tf->region); 1177 return; 1178 } 1179 1180 if (tf->may_fallthru) 1181 { 1182 /* Only reachable via the fallthru edge. Do nothing but let 1183 the two blocks run together; we'll fall out the bottom. */ 1184 gimple_seq_add_seq (&tf->top_p_seq, finally); 1185 return; 1186 } 1187 1188 finally_label = create_artificial_label (loc); 1189 label_stmt = gimple_build_label (finally_label); 1190 gimple_seq_add_stmt (&tf->top_p_seq, label_stmt); 1191 1192 gimple_seq_add_seq (&tf->top_p_seq, finally); 1193 1194 q = tf->goto_queue; 1195 qe = q + tf->goto_queue_active; 1196 1197 if (tf->may_return) 1198 { 1199 /* Reachable by return expressions only. Redirect them. */ 1200 for (; q < qe; ++q) 1201 do_return_redirection (q, finally_label, NULL); 1202 replace_goto_queue (tf); 1203 } 1204 else 1205 { 1206 /* Reachable by goto expressions only. Redirect them. */ 1207 for (; q < qe; ++q) 1208 do_goto_redirection (q, finally_label, NULL, tf); 1209 replace_goto_queue (tf); 1210 1211 if (tf->dest_array[0] == tf->fallthru_label) 1212 { 1213 /* Reachable by goto to fallthru label only. Redirect it 1214 to the new label (already created, sadly), and do not 1215 emit the final branch out, or the fallthru label. */ 1216 tf->fallthru_label = NULL; 1217 return; 1218 } 1219 } 1220 1221 /* Place the original return/goto to the original destination 1222 immediately after the finally block. */ 1223 x = tf->goto_queue[0].cont_stmt; 1224 gimple_seq_add_stmt (&tf->top_p_seq, x); 1225 maybe_record_in_goto_queue (state, x); 1226 } 1227 1228 /* A subroutine of lower_try_finally. There are multiple edges incoming 1229 and outgoing from the finally block. Implement this by duplicating the 1230 finally block for every destination. */ 1231 1232 static void 1233 lower_try_finally_copy (struct leh_state *state, struct leh_tf_state *tf) 1234 { 1235 gimple_seq finally; 1236 gimple_seq new_stmt; 1237 gimple_seq seq; 1238 gimple *x; 1239 geh_else *eh_else; 1240 tree tmp; 1241 location_t tf_loc = gimple_location (tf->try_finally_expr); 1242 1243 finally = gimple_try_cleanup (tf->top_p); 1244 1245 /* Notice EH_ELSE, and simplify some of the remaining code 1246 by considering FINALLY to be the normal return path only. */ 1247 eh_else = get_eh_else (finally); 1248 if (eh_else) 1249 finally = gimple_eh_else_n_body (eh_else); 1250 1251 tf->top_p_seq = gimple_try_eval (tf->top_p); 1252 new_stmt = NULL; 1253 1254 if (tf->may_fallthru) 1255 { 1256 seq = lower_try_finally_dup_block (finally, state, tf_loc); 1257 lower_eh_constructs_1 (state, &seq); 1258 gimple_seq_add_seq (&new_stmt, seq); 1259 1260 tmp = lower_try_finally_fallthru_label (tf); 1261 x = gimple_build_goto (tmp); 1262 gimple_set_location (x, tf_loc); 1263 gimple_seq_add_stmt (&new_stmt, x); 1264 } 1265 1266 if (tf->may_throw) 1267 { 1268 /* We don't need to copy the EH path of EH_ELSE, 1269 since it is only emitted once. */ 1270 if (eh_else) 1271 seq = gimple_eh_else_e_body (eh_else); 1272 else 1273 seq = lower_try_finally_dup_block (finally, state, tf_loc); 1274 lower_eh_constructs_1 (state, &seq); 1275 1276 emit_post_landing_pad (&eh_seq, tf->region); 1277 gimple_seq_add_seq (&eh_seq, seq); 1278 emit_resx (&eh_seq, tf->region); 1279 } 1280 1281 if (tf->goto_queue) 1282 { 1283 struct goto_queue_node *q, *qe; 1284 int return_index, index; 1285 struct labels_s 1286 { 1287 struct goto_queue_node *q; 1288 tree label; 1289 } *labels; 1290 1291 return_index = tf->dest_array.length (); 1292 labels = XCNEWVEC (struct labels_s, return_index + 1); 1293 1294 q = tf->goto_queue; 1295 qe = q + tf->goto_queue_active; 1296 for (; q < qe; q++) 1297 { 1298 index = q->index < 0 ? return_index : q->index; 1299 1300 if (!labels[index].q) 1301 labels[index].q = q; 1302 } 1303 1304 for (index = 0; index < return_index + 1; index++) 1305 { 1306 tree lab; 1307 1308 q = labels[index].q; 1309 if (! q) 1310 continue; 1311 1312 lab = labels[index].label 1313 = create_artificial_label (tf_loc); 1314 1315 if (index == return_index) 1316 do_return_redirection (q, lab, NULL); 1317 else 1318 do_goto_redirection (q, lab, NULL, tf); 1319 1320 x = gimple_build_label (lab); 1321 gimple_seq_add_stmt (&new_stmt, x); 1322 1323 seq = lower_try_finally_dup_block (finally, state, q->location); 1324 lower_eh_constructs_1 (state, &seq); 1325 gimple_seq_add_seq (&new_stmt, seq); 1326 1327 gimple_seq_add_stmt (&new_stmt, q->cont_stmt); 1328 maybe_record_in_goto_queue (state, q->cont_stmt); 1329 } 1330 1331 for (q = tf->goto_queue; q < qe; q++) 1332 { 1333 tree lab; 1334 1335 index = q->index < 0 ? return_index : q->index; 1336 1337 if (labels[index].q == q) 1338 continue; 1339 1340 lab = labels[index].label; 1341 1342 if (index == return_index) 1343 do_return_redirection (q, lab, NULL); 1344 else 1345 do_goto_redirection (q, lab, NULL, tf); 1346 } 1347 1348 replace_goto_queue (tf); 1349 free (labels); 1350 } 1351 1352 /* Need to link new stmts after running replace_goto_queue due 1353 to not wanting to process the same goto stmts twice. */ 1354 gimple_seq_add_seq (&tf->top_p_seq, new_stmt); 1355 } 1356 1357 /* A subroutine of lower_try_finally. There are multiple edges incoming 1358 and outgoing from the finally block. Implement this by instrumenting 1359 each incoming edge and creating a switch statement at the end of the 1360 finally block that branches to the appropriate destination. */ 1361 1362 static void 1363 lower_try_finally_switch (struct leh_state *state, struct leh_tf_state *tf) 1364 { 1365 struct goto_queue_node *q, *qe; 1366 tree finally_tmp, finally_label; 1367 int return_index, eh_index, fallthru_index; 1368 int nlabels, ndests, j, last_case_index; 1369 tree last_case; 1370 auto_vec<tree> case_label_vec; 1371 gimple_seq switch_body = NULL; 1372 gimple *x; 1373 geh_else *eh_else; 1374 tree tmp; 1375 gimple *switch_stmt; 1376 gimple_seq finally; 1377 hash_map<tree, gimple *> *cont_map = NULL; 1378 /* The location of the TRY_FINALLY stmt. */ 1379 location_t tf_loc = gimple_location (tf->try_finally_expr); 1380 /* The location of the finally block. */ 1381 location_t finally_loc; 1382 1383 finally = gimple_try_cleanup (tf->top_p); 1384 eh_else = get_eh_else (finally); 1385 1386 /* Mash the TRY block to the head of the chain. */ 1387 tf->top_p_seq = gimple_try_eval (tf->top_p); 1388 1389 /* The location of the finally is either the last stmt in the finally 1390 block or the location of the TRY_FINALLY itself. */ 1391 x = gimple_seq_last_stmt (finally); 1392 finally_loc = x ? gimple_location (x) : tf_loc; 1393 1394 /* Prepare for switch statement generation. */ 1395 nlabels = tf->dest_array.length (); 1396 return_index = nlabels; 1397 eh_index = return_index + tf->may_return; 1398 fallthru_index = eh_index + (tf->may_throw && !eh_else); 1399 ndests = fallthru_index + tf->may_fallthru; 1400 1401 finally_tmp = create_tmp_var (integer_type_node, "finally_tmp"); 1402 finally_label = create_artificial_label (finally_loc); 1403 1404 /* We use vec::quick_push on case_label_vec throughout this function, 1405 since we know the size in advance and allocate precisely as muce 1406 space as needed. */ 1407 case_label_vec.create (ndests); 1408 last_case = NULL; 1409 last_case_index = 0; 1410 1411 /* Begin inserting code for getting to the finally block. Things 1412 are done in this order to correspond to the sequence the code is 1413 laid out. */ 1414 1415 if (tf->may_fallthru) 1416 { 1417 x = gimple_build_assign (finally_tmp, 1418 build_int_cst (integer_type_node, 1419 fallthru_index)); 1420 gimple_set_location (x, finally_loc); 1421 gimple_seq_add_stmt (&tf->top_p_seq, x); 1422 1423 tmp = build_int_cst (integer_type_node, fallthru_index); 1424 last_case = build_case_label (tmp, NULL, 1425 create_artificial_label (finally_loc)); 1426 case_label_vec.quick_push (last_case); 1427 last_case_index++; 1428 1429 x = gimple_build_label (CASE_LABEL (last_case)); 1430 gimple_seq_add_stmt (&switch_body, x); 1431 1432 tmp = lower_try_finally_fallthru_label (tf); 1433 x = gimple_build_goto (tmp); 1434 gimple_set_location (x, finally_loc); 1435 gimple_seq_add_stmt (&switch_body, x); 1436 } 1437 1438 /* For EH_ELSE, emit the exception path (plus resx) now, then 1439 subsequently we only need consider the normal path. */ 1440 if (eh_else) 1441 { 1442 if (tf->may_throw) 1443 { 1444 finally = gimple_eh_else_e_body (eh_else); 1445 lower_eh_constructs_1 (state, &finally); 1446 1447 emit_post_landing_pad (&eh_seq, tf->region); 1448 gimple_seq_add_seq (&eh_seq, finally); 1449 emit_resx (&eh_seq, tf->region); 1450 } 1451 1452 finally = gimple_eh_else_n_body (eh_else); 1453 } 1454 else if (tf->may_throw) 1455 { 1456 emit_post_landing_pad (&eh_seq, tf->region); 1457 1458 x = gimple_build_assign (finally_tmp, 1459 build_int_cst (integer_type_node, eh_index)); 1460 gimple_seq_add_stmt (&eh_seq, x); 1461 1462 x = gimple_build_goto (finally_label); 1463 gimple_set_location (x, tf_loc); 1464 gimple_seq_add_stmt (&eh_seq, x); 1465 1466 tmp = build_int_cst (integer_type_node, eh_index); 1467 last_case = build_case_label (tmp, NULL, 1468 create_artificial_label (tf_loc)); 1469 case_label_vec.quick_push (last_case); 1470 last_case_index++; 1471 1472 x = gimple_build_label (CASE_LABEL (last_case)); 1473 gimple_seq_add_stmt (&eh_seq, x); 1474 emit_resx (&eh_seq, tf->region); 1475 } 1476 1477 x = gimple_build_label (finally_label); 1478 gimple_seq_add_stmt (&tf->top_p_seq, x); 1479 1480 lower_eh_constructs_1 (state, &finally); 1481 gimple_seq_add_seq (&tf->top_p_seq, finally); 1482 1483 /* Redirect each incoming goto edge. */ 1484 q = tf->goto_queue; 1485 qe = q + tf->goto_queue_active; 1486 j = last_case_index + tf->may_return; 1487 /* Prepare the assignments to finally_tmp that are executed upon the 1488 entrance through a particular edge. */ 1489 for (; q < qe; ++q) 1490 { 1491 gimple_seq mod = NULL; 1492 int switch_id; 1493 unsigned int case_index; 1494 1495 if (q->index < 0) 1496 { 1497 x = gimple_build_assign (finally_tmp, 1498 build_int_cst (integer_type_node, 1499 return_index)); 1500 gimple_seq_add_stmt (&mod, x); 1501 do_return_redirection (q, finally_label, mod); 1502 switch_id = return_index; 1503 } 1504 else 1505 { 1506 x = gimple_build_assign (finally_tmp, 1507 build_int_cst (integer_type_node, q->index)); 1508 gimple_seq_add_stmt (&mod, x); 1509 do_goto_redirection (q, finally_label, mod, tf); 1510 switch_id = q->index; 1511 } 1512 1513 case_index = j + q->index; 1514 if (case_label_vec.length () <= case_index || !case_label_vec[case_index]) 1515 { 1516 tree case_lab; 1517 tmp = build_int_cst (integer_type_node, switch_id); 1518 case_lab = build_case_label (tmp, NULL, 1519 create_artificial_label (tf_loc)); 1520 /* We store the cont_stmt in the pointer map, so that we can recover 1521 it in the loop below. */ 1522 if (!cont_map) 1523 cont_map = new hash_map<tree, gimple *>; 1524 cont_map->put (case_lab, q->cont_stmt); 1525 case_label_vec.quick_push (case_lab); 1526 } 1527 } 1528 for (j = last_case_index; j < last_case_index + nlabels; j++) 1529 { 1530 gimple *cont_stmt; 1531 1532 last_case = case_label_vec[j]; 1533 1534 gcc_assert (last_case); 1535 gcc_assert (cont_map); 1536 1537 cont_stmt = *cont_map->get (last_case); 1538 1539 x = gimple_build_label (CASE_LABEL (last_case)); 1540 gimple_seq_add_stmt (&switch_body, x); 1541 gimple_seq_add_stmt (&switch_body, cont_stmt); 1542 maybe_record_in_goto_queue (state, cont_stmt); 1543 } 1544 if (cont_map) 1545 delete cont_map; 1546 1547 replace_goto_queue (tf); 1548 1549 /* Make sure that the last case is the default label, as one is required. 1550 Then sort the labels, which is also required in GIMPLE. */ 1551 CASE_LOW (last_case) = NULL; 1552 tree tem = case_label_vec.pop (); 1553 gcc_assert (tem == last_case); 1554 sort_case_labels (case_label_vec); 1555 1556 /* Build the switch statement, setting last_case to be the default 1557 label. */ 1558 switch_stmt = gimple_build_switch (finally_tmp, last_case, 1559 case_label_vec); 1560 gimple_set_location (switch_stmt, finally_loc); 1561 1562 /* Need to link SWITCH_STMT after running replace_goto_queue 1563 due to not wanting to process the same goto stmts twice. */ 1564 gimple_seq_add_stmt (&tf->top_p_seq, switch_stmt); 1565 gimple_seq_add_seq (&tf->top_p_seq, switch_body); 1566 } 1567 1568 /* Decide whether or not we are going to duplicate the finally block. 1569 There are several considerations. 1570 1571 Second, we'd like to prevent egregious code growth. One way to 1572 do this is to estimate the size of the finally block, multiply 1573 that by the number of copies we'd need to make, and compare against 1574 the estimate of the size of the switch machinery we'd have to add. */ 1575 1576 static bool 1577 decide_copy_try_finally (int ndests, bool may_throw, gimple_seq finally) 1578 { 1579 int f_estimate, sw_estimate; 1580 geh_else *eh_else; 1581 1582 /* If there's an EH_ELSE involved, the exception path is separate 1583 and really doesn't come into play for this computation. */ 1584 eh_else = get_eh_else (finally); 1585 if (eh_else) 1586 { 1587 ndests -= may_throw; 1588 finally = gimple_eh_else_n_body (eh_else); 1589 } 1590 1591 if (!optimize) 1592 { 1593 gimple_stmt_iterator gsi; 1594 1595 if (ndests == 1) 1596 return true; 1597 1598 for (gsi = gsi_start (finally); !gsi_end_p (gsi); gsi_next (&gsi)) 1599 { 1600 /* Duplicate __builtin_stack_restore in the hope of eliminating it 1601 on the EH paths and, consequently, useless cleanups. */ 1602 gimple *stmt = gsi_stmt (gsi); 1603 if (!is_gimple_debug (stmt) 1604 && !gimple_clobber_p (stmt) 1605 && !gimple_call_builtin_p (stmt, BUILT_IN_STACK_RESTORE)) 1606 return false; 1607 } 1608 return true; 1609 } 1610 1611 /* Finally estimate N times, plus N gotos. */ 1612 f_estimate = estimate_num_insns_seq (finally, &eni_size_weights); 1613 f_estimate = (f_estimate + 1) * ndests; 1614 1615 /* Switch statement (cost 10), N variable assignments, N gotos. */ 1616 sw_estimate = 10 + 2 * ndests; 1617 1618 /* Optimize for size clearly wants our best guess. */ 1619 if (optimize_function_for_size_p (cfun)) 1620 return f_estimate < sw_estimate; 1621 1622 /* ??? These numbers are completely made up so far. */ 1623 if (optimize > 1) 1624 return f_estimate < 100 || f_estimate < sw_estimate * 2; 1625 else 1626 return f_estimate < 40 || f_estimate * 2 < sw_estimate * 3; 1627 } 1628 1629 /* REG is the enclosing region for a possible cleanup region, or the region 1630 itself. Returns TRUE if such a region would be unreachable. 1631 1632 Cleanup regions within a must-not-throw region aren't actually reachable 1633 even if there are throwing stmts within them, because the personality 1634 routine will call terminate before unwinding. */ 1635 1636 static bool 1637 cleanup_is_dead_in (eh_region reg) 1638 { 1639 while (reg && reg->type == ERT_CLEANUP) 1640 reg = reg->outer; 1641 return (reg && reg->type == ERT_MUST_NOT_THROW); 1642 } 1643 1644 /* A subroutine of lower_eh_constructs_1. Lower a GIMPLE_TRY_FINALLY nodes 1645 to a sequence of labels and blocks, plus the exception region trees 1646 that record all the magic. This is complicated by the need to 1647 arrange for the FINALLY block to be executed on all exits. */ 1648 1649 static gimple_seq 1650 lower_try_finally (struct leh_state *state, gtry *tp) 1651 { 1652 struct leh_tf_state this_tf; 1653 struct leh_state this_state; 1654 int ndests; 1655 gimple_seq old_eh_seq; 1656 1657 /* Process the try block. */ 1658 1659 memset (&this_tf, 0, sizeof (this_tf)); 1660 this_tf.try_finally_expr = tp; 1661 this_tf.top_p = tp; 1662 this_tf.outer = state; 1663 if (using_eh_for_cleanups_p () && !cleanup_is_dead_in (state->cur_region)) 1664 { 1665 this_tf.region = gen_eh_region_cleanup (state->cur_region); 1666 this_state.cur_region = this_tf.region; 1667 } 1668 else 1669 { 1670 this_tf.region = NULL; 1671 this_state.cur_region = state->cur_region; 1672 } 1673 1674 this_state.ehp_region = state->ehp_region; 1675 this_state.tf = &this_tf; 1676 1677 old_eh_seq = eh_seq; 1678 eh_seq = NULL; 1679 1680 lower_eh_constructs_1 (&this_state, gimple_try_eval_ptr (tp)); 1681 1682 /* Determine if the try block is escaped through the bottom. */ 1683 this_tf.may_fallthru = gimple_seq_may_fallthru (gimple_try_eval (tp)); 1684 1685 /* Determine if any exceptions are possible within the try block. */ 1686 if (this_tf.region) 1687 this_tf.may_throw = eh_region_may_contain_throw (this_tf.region); 1688 if (this_tf.may_throw) 1689 honor_protect_cleanup_actions (state, &this_state, &this_tf); 1690 1691 /* Determine how many edges (still) reach the finally block. Or rather, 1692 how many destinations are reached by the finally block. Use this to 1693 determine how we process the finally block itself. */ 1694 1695 ndests = this_tf.dest_array.length (); 1696 ndests += this_tf.may_fallthru; 1697 ndests += this_tf.may_return; 1698 ndests += this_tf.may_throw; 1699 1700 /* If the FINALLY block is not reachable, dike it out. */ 1701 if (ndests == 0) 1702 { 1703 gimple_seq_add_seq (&this_tf.top_p_seq, gimple_try_eval (tp)); 1704 gimple_try_set_cleanup (tp, NULL); 1705 } 1706 /* If the finally block doesn't fall through, then any destination 1707 we might try to impose there isn't reached either. There may be 1708 some minor amount of cleanup and redirection still needed. */ 1709 else if (!gimple_seq_may_fallthru (gimple_try_cleanup (tp))) 1710 lower_try_finally_nofallthru (state, &this_tf); 1711 1712 /* We can easily special-case redirection to a single destination. */ 1713 else if (ndests == 1) 1714 lower_try_finally_onedest (state, &this_tf); 1715 else if (decide_copy_try_finally (ndests, this_tf.may_throw, 1716 gimple_try_cleanup (tp))) 1717 lower_try_finally_copy (state, &this_tf); 1718 else 1719 lower_try_finally_switch (state, &this_tf); 1720 1721 /* If someone requested we add a label at the end of the transformed 1722 block, do so. */ 1723 if (this_tf.fallthru_label) 1724 { 1725 /* This must be reached only if ndests == 0. */ 1726 gimple *x = gimple_build_label (this_tf.fallthru_label); 1727 gimple_seq_add_stmt (&this_tf.top_p_seq, x); 1728 } 1729 1730 this_tf.dest_array.release (); 1731 free (this_tf.goto_queue); 1732 if (this_tf.goto_queue_map) 1733 delete this_tf.goto_queue_map; 1734 1735 /* If there was an old (aka outer) eh_seq, append the current eh_seq. 1736 If there was no old eh_seq, then the append is trivially already done. */ 1737 if (old_eh_seq) 1738 { 1739 if (eh_seq == NULL) 1740 eh_seq = old_eh_seq; 1741 else 1742 { 1743 gimple_seq new_eh_seq = eh_seq; 1744 eh_seq = old_eh_seq; 1745 gimple_seq_add_seq (&eh_seq, new_eh_seq); 1746 } 1747 } 1748 1749 return this_tf.top_p_seq; 1750 } 1751 1752 /* A subroutine of lower_eh_constructs_1. Lower a GIMPLE_TRY_CATCH with a 1753 list of GIMPLE_CATCH to a sequence of labels and blocks, plus the 1754 exception region trees that records all the magic. */ 1755 1756 static gimple_seq 1757 lower_catch (struct leh_state *state, gtry *tp) 1758 { 1759 eh_region try_region = NULL; 1760 struct leh_state this_state = *state; 1761 gimple_stmt_iterator gsi; 1762 tree out_label; 1763 gimple_seq new_seq, cleanup; 1764 gimple *x; 1765 location_t try_catch_loc = gimple_location (tp); 1766 1767 if (flag_exceptions) 1768 { 1769 try_region = gen_eh_region_try (state->cur_region); 1770 this_state.cur_region = try_region; 1771 } 1772 1773 lower_eh_constructs_1 (&this_state, gimple_try_eval_ptr (tp)); 1774 1775 if (!eh_region_may_contain_throw (try_region)) 1776 return gimple_try_eval (tp); 1777 1778 new_seq = NULL; 1779 emit_eh_dispatch (&new_seq, try_region); 1780 emit_resx (&new_seq, try_region); 1781 1782 this_state.cur_region = state->cur_region; 1783 this_state.ehp_region = try_region; 1784 1785 /* Add eh_seq from lowering EH in the cleanup sequence after the cleanup 1786 itself, so that e.g. for coverage purposes the nested cleanups don't 1787 appear before the cleanup body. See PR64634 for details. */ 1788 gimple_seq old_eh_seq = eh_seq; 1789 eh_seq = NULL; 1790 1791 out_label = NULL; 1792 cleanup = gimple_try_cleanup (tp); 1793 for (gsi = gsi_start (cleanup); 1794 !gsi_end_p (gsi); 1795 gsi_next (&gsi)) 1796 { 1797 eh_catch c; 1798 gcatch *catch_stmt; 1799 gimple_seq handler; 1800 1801 catch_stmt = as_a <gcatch *> (gsi_stmt (gsi)); 1802 c = gen_eh_region_catch (try_region, gimple_catch_types (catch_stmt)); 1803 1804 handler = gimple_catch_handler (catch_stmt); 1805 lower_eh_constructs_1 (&this_state, &handler); 1806 1807 c->label = create_artificial_label (UNKNOWN_LOCATION); 1808 x = gimple_build_label (c->label); 1809 gimple_seq_add_stmt (&new_seq, x); 1810 1811 gimple_seq_add_seq (&new_seq, handler); 1812 1813 if (gimple_seq_may_fallthru (new_seq)) 1814 { 1815 if (!out_label) 1816 out_label = create_artificial_label (try_catch_loc); 1817 1818 x = gimple_build_goto (out_label); 1819 gimple_seq_add_stmt (&new_seq, x); 1820 } 1821 if (!c->type_list) 1822 break; 1823 } 1824 1825 gimple_try_set_cleanup (tp, new_seq); 1826 1827 gimple_seq new_eh_seq = eh_seq; 1828 eh_seq = old_eh_seq; 1829 gimple_seq ret_seq = frob_into_branch_around (tp, try_region, out_label); 1830 gimple_seq_add_seq (&eh_seq, new_eh_seq); 1831 return ret_seq; 1832 } 1833 1834 /* A subroutine of lower_eh_constructs_1. Lower a GIMPLE_TRY with a 1835 GIMPLE_EH_FILTER to a sequence of labels and blocks, plus the exception 1836 region trees that record all the magic. */ 1837 1838 static gimple_seq 1839 lower_eh_filter (struct leh_state *state, gtry *tp) 1840 { 1841 struct leh_state this_state = *state; 1842 eh_region this_region = NULL; 1843 gimple *inner, *x; 1844 gimple_seq new_seq; 1845 1846 inner = gimple_seq_first_stmt (gimple_try_cleanup (tp)); 1847 1848 if (flag_exceptions) 1849 { 1850 this_region = gen_eh_region_allowed (state->cur_region, 1851 gimple_eh_filter_types (inner)); 1852 this_state.cur_region = this_region; 1853 } 1854 1855 lower_eh_constructs_1 (&this_state, gimple_try_eval_ptr (tp)); 1856 1857 if (!eh_region_may_contain_throw (this_region)) 1858 return gimple_try_eval (tp); 1859 1860 new_seq = NULL; 1861 this_state.cur_region = state->cur_region; 1862 this_state.ehp_region = this_region; 1863 1864 emit_eh_dispatch (&new_seq, this_region); 1865 emit_resx (&new_seq, this_region); 1866 1867 this_region->u.allowed.label = create_artificial_label (UNKNOWN_LOCATION); 1868 x = gimple_build_label (this_region->u.allowed.label); 1869 gimple_seq_add_stmt (&new_seq, x); 1870 1871 lower_eh_constructs_1 (&this_state, gimple_eh_filter_failure_ptr (inner)); 1872 gimple_seq_add_seq (&new_seq, gimple_eh_filter_failure (inner)); 1873 1874 gimple_try_set_cleanup (tp, new_seq); 1875 1876 return frob_into_branch_around (tp, this_region, NULL); 1877 } 1878 1879 /* A subroutine of lower_eh_constructs_1. Lower a GIMPLE_TRY with 1880 an GIMPLE_EH_MUST_NOT_THROW to a sequence of labels and blocks, 1881 plus the exception region trees that record all the magic. */ 1882 1883 static gimple_seq 1884 lower_eh_must_not_throw (struct leh_state *state, gtry *tp) 1885 { 1886 struct leh_state this_state = *state; 1887 1888 if (flag_exceptions) 1889 { 1890 gimple *inner = gimple_seq_first_stmt (gimple_try_cleanup (tp)); 1891 eh_region this_region; 1892 1893 this_region = gen_eh_region_must_not_throw (state->cur_region); 1894 this_region->u.must_not_throw.failure_decl 1895 = gimple_eh_must_not_throw_fndecl ( 1896 as_a <geh_mnt *> (inner)); 1897 this_region->u.must_not_throw.failure_loc 1898 = LOCATION_LOCUS (gimple_location (tp)); 1899 1900 /* In order to get mangling applied to this decl, we must mark it 1901 used now. Otherwise, pass_ipa_free_lang_data won't think it 1902 needs to happen. */ 1903 TREE_USED (this_region->u.must_not_throw.failure_decl) = 1; 1904 1905 this_state.cur_region = this_region; 1906 } 1907 1908 lower_eh_constructs_1 (&this_state, gimple_try_eval_ptr (tp)); 1909 1910 return gimple_try_eval (tp); 1911 } 1912 1913 /* Implement a cleanup expression. This is similar to try-finally, 1914 except that we only execute the cleanup block for exception edges. */ 1915 1916 static gimple_seq 1917 lower_cleanup (struct leh_state *state, gtry *tp) 1918 { 1919 struct leh_state this_state = *state; 1920 eh_region this_region = NULL; 1921 struct leh_tf_state fake_tf; 1922 gimple_seq result; 1923 bool cleanup_dead = cleanup_is_dead_in (state->cur_region); 1924 1925 if (flag_exceptions && !cleanup_dead) 1926 { 1927 this_region = gen_eh_region_cleanup (state->cur_region); 1928 this_state.cur_region = this_region; 1929 } 1930 1931 lower_eh_constructs_1 (&this_state, gimple_try_eval_ptr (tp)); 1932 1933 if (cleanup_dead || !eh_region_may_contain_throw (this_region)) 1934 return gimple_try_eval (tp); 1935 1936 /* Build enough of a try-finally state so that we can reuse 1937 honor_protect_cleanup_actions. */ 1938 memset (&fake_tf, 0, sizeof (fake_tf)); 1939 fake_tf.top_p = fake_tf.try_finally_expr = tp; 1940 fake_tf.outer = state; 1941 fake_tf.region = this_region; 1942 fake_tf.may_fallthru = gimple_seq_may_fallthru (gimple_try_eval (tp)); 1943 fake_tf.may_throw = true; 1944 1945 honor_protect_cleanup_actions (state, NULL, &fake_tf); 1946 1947 if (fake_tf.may_throw) 1948 { 1949 /* In this case honor_protect_cleanup_actions had nothing to do, 1950 and we should process this normally. */ 1951 lower_eh_constructs_1 (state, gimple_try_cleanup_ptr (tp)); 1952 result = frob_into_branch_around (tp, this_region, 1953 fake_tf.fallthru_label); 1954 } 1955 else 1956 { 1957 /* In this case honor_protect_cleanup_actions did nearly all of 1958 the work. All we have left is to append the fallthru_label. */ 1959 1960 result = gimple_try_eval (tp); 1961 if (fake_tf.fallthru_label) 1962 { 1963 gimple *x = gimple_build_label (fake_tf.fallthru_label); 1964 gimple_seq_add_stmt (&result, x); 1965 } 1966 } 1967 return result; 1968 } 1969 1970 /* Main loop for lowering eh constructs. Also moves gsi to the next 1971 statement. */ 1972 1973 static void 1974 lower_eh_constructs_2 (struct leh_state *state, gimple_stmt_iterator *gsi) 1975 { 1976 gimple_seq replace; 1977 gimple *x; 1978 gimple *stmt = gsi_stmt (*gsi); 1979 1980 switch (gimple_code (stmt)) 1981 { 1982 case GIMPLE_CALL: 1983 { 1984 tree fndecl = gimple_call_fndecl (stmt); 1985 tree rhs, lhs; 1986 1987 if (fndecl && DECL_BUILT_IN_CLASS (fndecl) == BUILT_IN_NORMAL) 1988 switch (DECL_FUNCTION_CODE (fndecl)) 1989 { 1990 case BUILT_IN_EH_POINTER: 1991 /* The front end may have generated a call to 1992 __builtin_eh_pointer (0) within a catch region. Replace 1993 this zero argument with the current catch region number. */ 1994 if (state->ehp_region) 1995 { 1996 tree nr = build_int_cst (integer_type_node, 1997 state->ehp_region->index); 1998 gimple_call_set_arg (stmt, 0, nr); 1999 } 2000 else 2001 { 2002 /* The user has dome something silly. Remove it. */ 2003 rhs = null_pointer_node; 2004 goto do_replace; 2005 } 2006 break; 2007 2008 case BUILT_IN_EH_FILTER: 2009 /* ??? This should never appear, but since it's a builtin it 2010 is accessible to abuse by users. Just remove it and 2011 replace the use with the arbitrary value zero. */ 2012 rhs = build_int_cst (TREE_TYPE (TREE_TYPE (fndecl)), 0); 2013 do_replace: 2014 lhs = gimple_call_lhs (stmt); 2015 x = gimple_build_assign (lhs, rhs); 2016 gsi_insert_before (gsi, x, GSI_SAME_STMT); 2017 /* FALLTHRU */ 2018 2019 case BUILT_IN_EH_COPY_VALUES: 2020 /* Likewise this should not appear. Remove it. */ 2021 gsi_remove (gsi, true); 2022 return; 2023 2024 default: 2025 break; 2026 } 2027 } 2028 /* FALLTHRU */ 2029 2030 case GIMPLE_ASSIGN: 2031 /* If the stmt can throw use a new temporary for the assignment 2032 to a LHS. This makes sure the old value of the LHS is 2033 available on the EH edge. Only do so for statements that 2034 potentially fall through (no noreturn calls e.g.), otherwise 2035 this new assignment might create fake fallthru regions. */ 2036 if (stmt_could_throw_p (stmt) 2037 && gimple_has_lhs (stmt) 2038 && gimple_stmt_may_fallthru (stmt) 2039 && !tree_could_throw_p (gimple_get_lhs (stmt)) 2040 && is_gimple_reg_type (TREE_TYPE (gimple_get_lhs (stmt)))) 2041 { 2042 tree lhs = gimple_get_lhs (stmt); 2043 tree tmp = create_tmp_var (TREE_TYPE (lhs)); 2044 gimple *s = gimple_build_assign (lhs, tmp); 2045 gimple_set_location (s, gimple_location (stmt)); 2046 gimple_set_block (s, gimple_block (stmt)); 2047 gimple_set_lhs (stmt, tmp); 2048 if (TREE_CODE (TREE_TYPE (tmp)) == COMPLEX_TYPE 2049 || TREE_CODE (TREE_TYPE (tmp)) == VECTOR_TYPE) 2050 DECL_GIMPLE_REG_P (tmp) = 1; 2051 gsi_insert_after (gsi, s, GSI_SAME_STMT); 2052 } 2053 /* Look for things that can throw exceptions, and record them. */ 2054 if (state->cur_region && stmt_could_throw_p (stmt)) 2055 { 2056 record_stmt_eh_region (state->cur_region, stmt); 2057 note_eh_region_may_contain_throw (state->cur_region); 2058 } 2059 break; 2060 2061 case GIMPLE_COND: 2062 case GIMPLE_GOTO: 2063 case GIMPLE_RETURN: 2064 maybe_record_in_goto_queue (state, stmt); 2065 break; 2066 2067 case GIMPLE_SWITCH: 2068 verify_norecord_switch_expr (state, as_a <gswitch *> (stmt)); 2069 break; 2070 2071 case GIMPLE_TRY: 2072 { 2073 gtry *try_stmt = as_a <gtry *> (stmt); 2074 if (gimple_try_kind (try_stmt) == GIMPLE_TRY_FINALLY) 2075 replace = lower_try_finally (state, try_stmt); 2076 else 2077 { 2078 x = gimple_seq_first_stmt (gimple_try_cleanup (try_stmt)); 2079 if (!x) 2080 { 2081 replace = gimple_try_eval (try_stmt); 2082 lower_eh_constructs_1 (state, &replace); 2083 } 2084 else 2085 switch (gimple_code (x)) 2086 { 2087 case GIMPLE_CATCH: 2088 replace = lower_catch (state, try_stmt); 2089 break; 2090 case GIMPLE_EH_FILTER: 2091 replace = lower_eh_filter (state, try_stmt); 2092 break; 2093 case GIMPLE_EH_MUST_NOT_THROW: 2094 replace = lower_eh_must_not_throw (state, try_stmt); 2095 break; 2096 case GIMPLE_EH_ELSE: 2097 /* This code is only valid with GIMPLE_TRY_FINALLY. */ 2098 gcc_unreachable (); 2099 default: 2100 replace = lower_cleanup (state, try_stmt); 2101 break; 2102 } 2103 } 2104 } 2105 2106 /* Remove the old stmt and insert the transformed sequence 2107 instead. */ 2108 gsi_insert_seq_before (gsi, replace, GSI_SAME_STMT); 2109 gsi_remove (gsi, true); 2110 2111 /* Return since we don't want gsi_next () */ 2112 return; 2113 2114 case GIMPLE_EH_ELSE: 2115 /* We should be eliminating this in lower_try_finally et al. */ 2116 gcc_unreachable (); 2117 2118 default: 2119 /* A type, a decl, or some kind of statement that we're not 2120 interested in. Don't walk them. */ 2121 break; 2122 } 2123 2124 gsi_next (gsi); 2125 } 2126 2127 /* A helper to unwrap a gimple_seq and feed stmts to lower_eh_constructs_2. */ 2128 2129 static void 2130 lower_eh_constructs_1 (struct leh_state *state, gimple_seq *pseq) 2131 { 2132 gimple_stmt_iterator gsi; 2133 for (gsi = gsi_start (*pseq); !gsi_end_p (gsi);) 2134 lower_eh_constructs_2 (state, &gsi); 2135 } 2136 2137 namespace { 2138 2139 const pass_data pass_data_lower_eh = 2140 { 2141 GIMPLE_PASS, /* type */ 2142 "eh", /* name */ 2143 OPTGROUP_NONE, /* optinfo_flags */ 2144 TV_TREE_EH, /* tv_id */ 2145 PROP_gimple_lcf, /* properties_required */ 2146 PROP_gimple_leh, /* properties_provided */ 2147 0, /* properties_destroyed */ 2148 0, /* todo_flags_start */ 2149 0, /* todo_flags_finish */ 2150 }; 2151 2152 class pass_lower_eh : public gimple_opt_pass 2153 { 2154 public: 2155 pass_lower_eh (gcc::context *ctxt) 2156 : gimple_opt_pass (pass_data_lower_eh, ctxt) 2157 {} 2158 2159 /* opt_pass methods: */ 2160 virtual unsigned int execute (function *); 2161 2162 }; // class pass_lower_eh 2163 2164 unsigned int 2165 pass_lower_eh::execute (function *fun) 2166 { 2167 struct leh_state null_state; 2168 gimple_seq bodyp; 2169 2170 bodyp = gimple_body (current_function_decl); 2171 if (bodyp == NULL) 2172 return 0; 2173 2174 finally_tree = new hash_table<finally_tree_hasher> (31); 2175 eh_region_may_contain_throw_map = BITMAP_ALLOC (NULL); 2176 memset (&null_state, 0, sizeof (null_state)); 2177 2178 collect_finally_tree_1 (bodyp, NULL); 2179 lower_eh_constructs_1 (&null_state, &bodyp); 2180 gimple_set_body (current_function_decl, bodyp); 2181 2182 /* We assume there's a return statement, or something, at the end of 2183 the function, and thus ploping the EH sequence afterward won't 2184 change anything. */ 2185 gcc_assert (!gimple_seq_may_fallthru (bodyp)); 2186 gimple_seq_add_seq (&bodyp, eh_seq); 2187 2188 /* We assume that since BODYP already existed, adding EH_SEQ to it 2189 didn't change its value, and we don't have to re-set the function. */ 2190 gcc_assert (bodyp == gimple_body (current_function_decl)); 2191 2192 delete finally_tree; 2193 finally_tree = NULL; 2194 BITMAP_FREE (eh_region_may_contain_throw_map); 2195 eh_seq = NULL; 2196 2197 /* If this function needs a language specific EH personality routine 2198 and the frontend didn't already set one do so now. */ 2199 if (function_needs_eh_personality (fun) == eh_personality_lang 2200 && !DECL_FUNCTION_PERSONALITY (current_function_decl)) 2201 DECL_FUNCTION_PERSONALITY (current_function_decl) 2202 = lang_hooks.eh_personality (); 2203 2204 return 0; 2205 } 2206 2207 } // anon namespace 2208 2209 gimple_opt_pass * 2210 make_pass_lower_eh (gcc::context *ctxt) 2211 { 2212 return new pass_lower_eh (ctxt); 2213 } 2214 2215 /* Create the multiple edges from an EH_DISPATCH statement to all of 2216 the possible handlers for its EH region. Return true if there's 2217 no fallthru edge; false if there is. */ 2218 2219 bool 2220 make_eh_dispatch_edges (geh_dispatch *stmt) 2221 { 2222 eh_region r; 2223 eh_catch c; 2224 basic_block src, dst; 2225 2226 r = get_eh_region_from_number (gimple_eh_dispatch_region (stmt)); 2227 src = gimple_bb (stmt); 2228 2229 switch (r->type) 2230 { 2231 case ERT_TRY: 2232 for (c = r->u.eh_try.first_catch; c ; c = c->next_catch) 2233 { 2234 dst = label_to_block (c->label); 2235 make_edge (src, dst, 0); 2236 2237 /* A catch-all handler doesn't have a fallthru. */ 2238 if (c->type_list == NULL) 2239 return false; 2240 } 2241 break; 2242 2243 case ERT_ALLOWED_EXCEPTIONS: 2244 dst = label_to_block (r->u.allowed.label); 2245 make_edge (src, dst, 0); 2246 break; 2247 2248 default: 2249 gcc_unreachable (); 2250 } 2251 2252 return true; 2253 } 2254 2255 /* Create the single EH edge from STMT to its nearest landing pad, 2256 if there is such a landing pad within the current function. */ 2257 2258 void 2259 make_eh_edges (gimple *stmt) 2260 { 2261 basic_block src, dst; 2262 eh_landing_pad lp; 2263 int lp_nr; 2264 2265 lp_nr = lookup_stmt_eh_lp (stmt); 2266 if (lp_nr <= 0) 2267 return; 2268 2269 lp = get_eh_landing_pad_from_number (lp_nr); 2270 gcc_assert (lp != NULL); 2271 2272 src = gimple_bb (stmt); 2273 dst = label_to_block (lp->post_landing_pad); 2274 make_edge (src, dst, EDGE_EH); 2275 } 2276 2277 /* Do the work in redirecting EDGE_IN to NEW_BB within the EH region tree; 2278 do not actually perform the final edge redirection. 2279 2280 CHANGE_REGION is true when we're being called from cleanup_empty_eh and 2281 we intend to change the destination EH region as well; this means 2282 EH_LANDING_PAD_NR must already be set on the destination block label. 2283 If false, we're being called from generic cfg manipulation code and we 2284 should preserve our place within the region tree. */ 2285 2286 static void 2287 redirect_eh_edge_1 (edge edge_in, basic_block new_bb, bool change_region) 2288 { 2289 eh_landing_pad old_lp, new_lp; 2290 basic_block old_bb; 2291 gimple *throw_stmt; 2292 int old_lp_nr, new_lp_nr; 2293 tree old_label, new_label; 2294 edge_iterator ei; 2295 edge e; 2296 2297 old_bb = edge_in->dest; 2298 old_label = gimple_block_label (old_bb); 2299 old_lp_nr = EH_LANDING_PAD_NR (old_label); 2300 gcc_assert (old_lp_nr > 0); 2301 old_lp = get_eh_landing_pad_from_number (old_lp_nr); 2302 2303 throw_stmt = last_stmt (edge_in->src); 2304 gcc_assert (lookup_stmt_eh_lp (throw_stmt) == old_lp_nr); 2305 2306 new_label = gimple_block_label (new_bb); 2307 2308 /* Look for an existing region that might be using NEW_BB already. */ 2309 new_lp_nr = EH_LANDING_PAD_NR (new_label); 2310 if (new_lp_nr) 2311 { 2312 new_lp = get_eh_landing_pad_from_number (new_lp_nr); 2313 gcc_assert (new_lp); 2314 2315 /* Unless CHANGE_REGION is true, the new and old landing pad 2316 had better be associated with the same EH region. */ 2317 gcc_assert (change_region || new_lp->region == old_lp->region); 2318 } 2319 else 2320 { 2321 new_lp = NULL; 2322 gcc_assert (!change_region); 2323 } 2324 2325 /* Notice when we redirect the last EH edge away from OLD_BB. */ 2326 FOR_EACH_EDGE (e, ei, old_bb->preds) 2327 if (e != edge_in && (e->flags & EDGE_EH)) 2328 break; 2329 2330 if (new_lp) 2331 { 2332 /* NEW_LP already exists. If there are still edges into OLD_LP, 2333 there's nothing to do with the EH tree. If there are no more 2334 edges into OLD_LP, then we want to remove OLD_LP as it is unused. 2335 If CHANGE_REGION is true, then our caller is expecting to remove 2336 the landing pad. */ 2337 if (e == NULL && !change_region) 2338 remove_eh_landing_pad (old_lp); 2339 } 2340 else 2341 { 2342 /* No correct landing pad exists. If there are no more edges 2343 into OLD_LP, then we can simply re-use the existing landing pad. 2344 Otherwise, we have to create a new landing pad. */ 2345 if (e == NULL) 2346 { 2347 EH_LANDING_PAD_NR (old_lp->post_landing_pad) = 0; 2348 new_lp = old_lp; 2349 } 2350 else 2351 new_lp = gen_eh_landing_pad (old_lp->region); 2352 new_lp->post_landing_pad = new_label; 2353 EH_LANDING_PAD_NR (new_label) = new_lp->index; 2354 } 2355 2356 /* Maybe move the throwing statement to the new region. */ 2357 if (old_lp != new_lp) 2358 { 2359 remove_stmt_from_eh_lp (throw_stmt); 2360 add_stmt_to_eh_lp (throw_stmt, new_lp->index); 2361 } 2362 } 2363 2364 /* Redirect EH edge E to NEW_BB. */ 2365 2366 edge 2367 redirect_eh_edge (edge edge_in, basic_block new_bb) 2368 { 2369 redirect_eh_edge_1 (edge_in, new_bb, false); 2370 return ssa_redirect_edge (edge_in, new_bb); 2371 } 2372 2373 /* This is a subroutine of gimple_redirect_edge_and_branch. Update the 2374 labels for redirecting a non-fallthru EH_DISPATCH edge E to NEW_BB. 2375 The actual edge update will happen in the caller. */ 2376 2377 void 2378 redirect_eh_dispatch_edge (geh_dispatch *stmt, edge e, basic_block new_bb) 2379 { 2380 tree new_lab = gimple_block_label (new_bb); 2381 bool any_changed = false; 2382 basic_block old_bb; 2383 eh_region r; 2384 eh_catch c; 2385 2386 r = get_eh_region_from_number (gimple_eh_dispatch_region (stmt)); 2387 switch (r->type) 2388 { 2389 case ERT_TRY: 2390 for (c = r->u.eh_try.first_catch; c ; c = c->next_catch) 2391 { 2392 old_bb = label_to_block (c->label); 2393 if (old_bb == e->dest) 2394 { 2395 c->label = new_lab; 2396 any_changed = true; 2397 } 2398 } 2399 break; 2400 2401 case ERT_ALLOWED_EXCEPTIONS: 2402 old_bb = label_to_block (r->u.allowed.label); 2403 gcc_assert (old_bb == e->dest); 2404 r->u.allowed.label = new_lab; 2405 any_changed = true; 2406 break; 2407 2408 default: 2409 gcc_unreachable (); 2410 } 2411 2412 gcc_assert (any_changed); 2413 } 2414 2415 /* Helper function for operation_could_trap_p and stmt_could_throw_p. */ 2416 2417 bool 2418 operation_could_trap_helper_p (enum tree_code op, 2419 bool fp_operation, 2420 bool honor_trapv, 2421 bool honor_nans, 2422 bool honor_snans, 2423 tree divisor, 2424 bool *handled) 2425 { 2426 *handled = true; 2427 switch (op) 2428 { 2429 case TRUNC_DIV_EXPR: 2430 case CEIL_DIV_EXPR: 2431 case FLOOR_DIV_EXPR: 2432 case ROUND_DIV_EXPR: 2433 case EXACT_DIV_EXPR: 2434 case CEIL_MOD_EXPR: 2435 case FLOOR_MOD_EXPR: 2436 case ROUND_MOD_EXPR: 2437 case TRUNC_MOD_EXPR: 2438 case RDIV_EXPR: 2439 if (honor_snans) 2440 return true; 2441 if (fp_operation) 2442 return flag_trapping_math; 2443 if (!TREE_CONSTANT (divisor) || integer_zerop (divisor)) 2444 return true; 2445 return false; 2446 2447 case LT_EXPR: 2448 case LE_EXPR: 2449 case GT_EXPR: 2450 case GE_EXPR: 2451 case LTGT_EXPR: 2452 /* Some floating point comparisons may trap. */ 2453 return honor_nans; 2454 2455 case EQ_EXPR: 2456 case NE_EXPR: 2457 case UNORDERED_EXPR: 2458 case ORDERED_EXPR: 2459 case UNLT_EXPR: 2460 case UNLE_EXPR: 2461 case UNGT_EXPR: 2462 case UNGE_EXPR: 2463 case UNEQ_EXPR: 2464 return honor_snans; 2465 2466 case NEGATE_EXPR: 2467 case ABS_EXPR: 2468 case CONJ_EXPR: 2469 /* These operations don't trap with floating point. */ 2470 if (honor_trapv) 2471 return true; 2472 return false; 2473 2474 case PLUS_EXPR: 2475 case MINUS_EXPR: 2476 case MULT_EXPR: 2477 /* Any floating arithmetic may trap. */ 2478 if (fp_operation && flag_trapping_math) 2479 return true; 2480 if (honor_trapv) 2481 return true; 2482 return false; 2483 2484 case COMPLEX_EXPR: 2485 case CONSTRUCTOR: 2486 /* Constructing an object cannot trap. */ 2487 return false; 2488 2489 default: 2490 /* Any floating arithmetic may trap. */ 2491 if (fp_operation && flag_trapping_math) 2492 return true; 2493 2494 *handled = false; 2495 return false; 2496 } 2497 } 2498 2499 /* Return true if operation OP may trap. FP_OPERATION is true if OP is applied 2500 on floating-point values. HONOR_TRAPV is true if OP is applied on integer 2501 type operands that may trap. If OP is a division operator, DIVISOR contains 2502 the value of the divisor. */ 2503 2504 bool 2505 operation_could_trap_p (enum tree_code op, bool fp_operation, bool honor_trapv, 2506 tree divisor) 2507 { 2508 bool honor_nans = (fp_operation && flag_trapping_math 2509 && !flag_finite_math_only); 2510 bool honor_snans = fp_operation && flag_signaling_nans != 0; 2511 bool handled; 2512 2513 if (TREE_CODE_CLASS (op) != tcc_comparison 2514 && TREE_CODE_CLASS (op) != tcc_unary 2515 && TREE_CODE_CLASS (op) != tcc_binary 2516 && op != FMA_EXPR) 2517 return false; 2518 2519 return operation_could_trap_helper_p (op, fp_operation, honor_trapv, 2520 honor_nans, honor_snans, divisor, 2521 &handled); 2522 } 2523 2524 2525 /* Returns true if it is possible to prove that the index of 2526 an array access REF (an ARRAY_REF expression) falls into the 2527 array bounds. */ 2528 2529 static bool 2530 in_array_bounds_p (tree ref) 2531 { 2532 tree idx = TREE_OPERAND (ref, 1); 2533 tree min, max; 2534 2535 if (TREE_CODE (idx) != INTEGER_CST) 2536 return false; 2537 2538 min = array_ref_low_bound (ref); 2539 max = array_ref_up_bound (ref); 2540 if (!min 2541 || !max 2542 || TREE_CODE (min) != INTEGER_CST 2543 || TREE_CODE (max) != INTEGER_CST) 2544 return false; 2545 2546 if (tree_int_cst_lt (idx, min) 2547 || tree_int_cst_lt (max, idx)) 2548 return false; 2549 2550 return true; 2551 } 2552 2553 /* Returns true if it is possible to prove that the range of 2554 an array access REF (an ARRAY_RANGE_REF expression) falls 2555 into the array bounds. */ 2556 2557 static bool 2558 range_in_array_bounds_p (tree ref) 2559 { 2560 tree domain_type = TYPE_DOMAIN (TREE_TYPE (ref)); 2561 tree range_min, range_max, min, max; 2562 2563 range_min = TYPE_MIN_VALUE (domain_type); 2564 range_max = TYPE_MAX_VALUE (domain_type); 2565 if (!range_min 2566 || !range_max 2567 || TREE_CODE (range_min) != INTEGER_CST 2568 || TREE_CODE (range_max) != INTEGER_CST) 2569 return false; 2570 2571 min = array_ref_low_bound (ref); 2572 max = array_ref_up_bound (ref); 2573 if (!min 2574 || !max 2575 || TREE_CODE (min) != INTEGER_CST 2576 || TREE_CODE (max) != INTEGER_CST) 2577 return false; 2578 2579 if (tree_int_cst_lt (range_min, min) 2580 || tree_int_cst_lt (max, range_max)) 2581 return false; 2582 2583 return true; 2584 } 2585 2586 /* Return true if EXPR can trap, as in dereferencing an invalid pointer 2587 location or floating point arithmetic. C.f. the rtl version, may_trap_p. 2588 This routine expects only GIMPLE lhs or rhs input. */ 2589 2590 bool 2591 tree_could_trap_p (tree expr) 2592 { 2593 enum tree_code code; 2594 bool fp_operation = false; 2595 bool honor_trapv = false; 2596 tree t, base, div = NULL_TREE; 2597 2598 if (!expr) 2599 return false; 2600 2601 code = TREE_CODE (expr); 2602 t = TREE_TYPE (expr); 2603 2604 if (t) 2605 { 2606 if (COMPARISON_CLASS_P (expr)) 2607 fp_operation = FLOAT_TYPE_P (TREE_TYPE (TREE_OPERAND (expr, 0))); 2608 else 2609 fp_operation = FLOAT_TYPE_P (t); 2610 honor_trapv = INTEGRAL_TYPE_P (t) && TYPE_OVERFLOW_TRAPS (t); 2611 } 2612 2613 if (TREE_CODE_CLASS (code) == tcc_binary) 2614 div = TREE_OPERAND (expr, 1); 2615 if (operation_could_trap_p (code, fp_operation, honor_trapv, div)) 2616 return true; 2617 2618 restart: 2619 switch (code) 2620 { 2621 case COMPONENT_REF: 2622 case REALPART_EXPR: 2623 case IMAGPART_EXPR: 2624 case BIT_FIELD_REF: 2625 case VIEW_CONVERT_EXPR: 2626 case WITH_SIZE_EXPR: 2627 expr = TREE_OPERAND (expr, 0); 2628 code = TREE_CODE (expr); 2629 goto restart; 2630 2631 case ARRAY_RANGE_REF: 2632 base = TREE_OPERAND (expr, 0); 2633 if (tree_could_trap_p (base)) 2634 return true; 2635 if (TREE_THIS_NOTRAP (expr)) 2636 return false; 2637 return !range_in_array_bounds_p (expr); 2638 2639 case ARRAY_REF: 2640 base = TREE_OPERAND (expr, 0); 2641 if (tree_could_trap_p (base)) 2642 return true; 2643 if (TREE_THIS_NOTRAP (expr)) 2644 return false; 2645 return !in_array_bounds_p (expr); 2646 2647 case TARGET_MEM_REF: 2648 case MEM_REF: 2649 if (TREE_CODE (TREE_OPERAND (expr, 0)) == ADDR_EXPR 2650 && tree_could_trap_p (TREE_OPERAND (TREE_OPERAND (expr, 0), 0))) 2651 return true; 2652 if (TREE_THIS_NOTRAP (expr)) 2653 return false; 2654 /* We cannot prove that the access is in-bounds when we have 2655 variable-index TARGET_MEM_REFs. */ 2656 if (code == TARGET_MEM_REF 2657 && (TMR_INDEX (expr) || TMR_INDEX2 (expr))) 2658 return true; 2659 if (TREE_CODE (TREE_OPERAND (expr, 0)) == ADDR_EXPR) 2660 { 2661 tree base = TREE_OPERAND (TREE_OPERAND (expr, 0), 0); 2662 poly_offset_int off = mem_ref_offset (expr); 2663 if (maybe_lt (off, 0)) 2664 return true; 2665 if (TREE_CODE (base) == STRING_CST) 2666 return maybe_le (TREE_STRING_LENGTH (base), off); 2667 tree size = DECL_SIZE_UNIT (base); 2668 if (size == NULL_TREE 2669 || !poly_int_tree_p (size) 2670 || maybe_le (wi::to_poly_offset (size), off)) 2671 return true; 2672 /* Now we are sure the first byte of the access is inside 2673 the object. */ 2674 return false; 2675 } 2676 return true; 2677 2678 case INDIRECT_REF: 2679 return !TREE_THIS_NOTRAP (expr); 2680 2681 case ASM_EXPR: 2682 return TREE_THIS_VOLATILE (expr); 2683 2684 case CALL_EXPR: 2685 t = get_callee_fndecl (expr); 2686 /* Assume that calls to weak functions may trap. */ 2687 if (!t || !DECL_P (t)) 2688 return true; 2689 if (DECL_WEAK (t)) 2690 return tree_could_trap_p (t); 2691 return false; 2692 2693 case FUNCTION_DECL: 2694 /* Assume that accesses to weak functions may trap, unless we know 2695 they are certainly defined in current TU or in some other 2696 LTO partition. */ 2697 if (DECL_WEAK (expr) && !DECL_COMDAT (expr) && DECL_EXTERNAL (expr)) 2698 { 2699 cgraph_node *node = cgraph_node::get (expr); 2700 if (node) 2701 node = node->function_symbol (); 2702 return !(node && node->in_other_partition); 2703 } 2704 return false; 2705 2706 case VAR_DECL: 2707 /* Assume that accesses to weak vars may trap, unless we know 2708 they are certainly defined in current TU or in some other 2709 LTO partition. */ 2710 if (DECL_WEAK (expr) && !DECL_COMDAT (expr) && DECL_EXTERNAL (expr)) 2711 { 2712 varpool_node *node = varpool_node::get (expr); 2713 if (node) 2714 node = node->ultimate_alias_target (); 2715 return !(node && node->in_other_partition); 2716 } 2717 return false; 2718 2719 default: 2720 return false; 2721 } 2722 } 2723 2724 /* Return non-NULL if there is an integer operation with trapping overflow 2725 we can rewrite into non-trapping. Called via walk_tree from 2726 rewrite_to_non_trapping_overflow. */ 2727 2728 static tree 2729 find_trapping_overflow (tree *tp, int *walk_subtrees, void *data) 2730 { 2731 if (EXPR_P (*tp) 2732 && ANY_INTEGRAL_TYPE_P (TREE_TYPE (*tp)) 2733 && !operation_no_trapping_overflow (TREE_TYPE (*tp), TREE_CODE (*tp))) 2734 return *tp; 2735 if (IS_TYPE_OR_DECL_P (*tp) 2736 || (TREE_CODE (*tp) == SAVE_EXPR && data == NULL)) 2737 *walk_subtrees = 0; 2738 return NULL_TREE; 2739 } 2740 2741 /* Rewrite selected operations into unsigned arithmetics, so that they 2742 don't trap on overflow. */ 2743 2744 static tree 2745 replace_trapping_overflow (tree *tp, int *walk_subtrees, void *data) 2746 { 2747 if (find_trapping_overflow (tp, walk_subtrees, data)) 2748 { 2749 tree type = TREE_TYPE (*tp); 2750 tree utype = unsigned_type_for (type); 2751 *walk_subtrees = 0; 2752 int len = TREE_OPERAND_LENGTH (*tp); 2753 for (int i = 0; i < len; ++i) 2754 walk_tree (&TREE_OPERAND (*tp, i), replace_trapping_overflow, 2755 data, (hash_set<tree> *) data); 2756 2757 if (TREE_CODE (*tp) == ABS_EXPR) 2758 { 2759 tree op = TREE_OPERAND (*tp, 0); 2760 op = save_expr (op); 2761 /* save_expr skips simple arithmetics, which is undesirable 2762 here, if it might trap due to flag_trapv. We need to 2763 force a SAVE_EXPR in the COND_EXPR condition, to evaluate 2764 it before the comparison. */ 2765 if (EXPR_P (op) 2766 && TREE_CODE (op) != SAVE_EXPR 2767 && walk_tree (&op, find_trapping_overflow, NULL, NULL)) 2768 { 2769 op = build1_loc (EXPR_LOCATION (op), SAVE_EXPR, type, op); 2770 TREE_SIDE_EFFECTS (op) = 1; 2771 } 2772 /* Change abs (op) to op < 0 ? -op : op and handle the NEGATE_EXPR 2773 like other signed integer trapping operations. */ 2774 tree cond = fold_build2 (LT_EXPR, boolean_type_node, 2775 op, build_int_cst (type, 0)); 2776 tree neg = fold_build1 (NEGATE_EXPR, utype, 2777 fold_convert (utype, op)); 2778 *tp = fold_build3 (COND_EXPR, type, cond, 2779 fold_convert (type, neg), op); 2780 } 2781 else 2782 { 2783 TREE_TYPE (*tp) = utype; 2784 len = TREE_OPERAND_LENGTH (*tp); 2785 for (int i = 0; i < len; ++i) 2786 TREE_OPERAND (*tp, i) 2787 = fold_convert (utype, TREE_OPERAND (*tp, i)); 2788 *tp = fold_convert (type, *tp); 2789 } 2790 } 2791 return NULL_TREE; 2792 } 2793 2794 /* If any subexpression of EXPR can trap due to -ftrapv, rewrite it 2795 using unsigned arithmetics to avoid traps in it. */ 2796 2797 tree 2798 rewrite_to_non_trapping_overflow (tree expr) 2799 { 2800 if (!flag_trapv) 2801 return expr; 2802 hash_set<tree> pset; 2803 if (!walk_tree (&expr, find_trapping_overflow, &pset, &pset)) 2804 return expr; 2805 expr = unshare_expr (expr); 2806 pset.empty (); 2807 walk_tree (&expr, replace_trapping_overflow, &pset, &pset); 2808 return expr; 2809 } 2810 2811 /* Helper for stmt_could_throw_p. Return true if STMT (assumed to be a 2812 an assignment or a conditional) may throw. */ 2813 2814 static bool 2815 stmt_could_throw_1_p (gassign *stmt) 2816 { 2817 enum tree_code code = gimple_assign_rhs_code (stmt); 2818 bool honor_nans = false; 2819 bool honor_snans = false; 2820 bool fp_operation = false; 2821 bool honor_trapv = false; 2822 tree t; 2823 size_t i; 2824 bool handled, ret; 2825 2826 if (TREE_CODE_CLASS (code) == tcc_comparison 2827 || TREE_CODE_CLASS (code) == tcc_unary 2828 || TREE_CODE_CLASS (code) == tcc_binary 2829 || code == FMA_EXPR) 2830 { 2831 if (TREE_CODE_CLASS (code) == tcc_comparison) 2832 t = TREE_TYPE (gimple_assign_rhs1 (stmt)); 2833 else 2834 t = gimple_expr_type (stmt); 2835 fp_operation = FLOAT_TYPE_P (t); 2836 if (fp_operation) 2837 { 2838 honor_nans = flag_trapping_math && !flag_finite_math_only; 2839 honor_snans = flag_signaling_nans != 0; 2840 } 2841 else if (INTEGRAL_TYPE_P (t) && TYPE_OVERFLOW_TRAPS (t)) 2842 honor_trapv = true; 2843 } 2844 2845 /* First check the LHS. */ 2846 if (tree_could_trap_p (gimple_assign_lhs (stmt))) 2847 return true; 2848 2849 /* Check if the main expression may trap. */ 2850 ret = operation_could_trap_helper_p (code, fp_operation, honor_trapv, 2851 honor_nans, honor_snans, 2852 gimple_assign_rhs2 (stmt), 2853 &handled); 2854 if (handled) 2855 return ret; 2856 2857 /* If the expression does not trap, see if any of the individual operands may 2858 trap. */ 2859 for (i = 1; i < gimple_num_ops (stmt); i++) 2860 if (tree_could_trap_p (gimple_op (stmt, i))) 2861 return true; 2862 2863 return false; 2864 } 2865 2866 2867 /* Return true if statement STMT could throw an exception. */ 2868 2869 bool 2870 stmt_could_throw_p (gimple *stmt) 2871 { 2872 if (!flag_exceptions) 2873 return false; 2874 2875 /* The only statements that can throw an exception are assignments, 2876 conditionals, calls, resx, and asms. */ 2877 switch (gimple_code (stmt)) 2878 { 2879 case GIMPLE_RESX: 2880 return true; 2881 2882 case GIMPLE_CALL: 2883 return !gimple_call_nothrow_p (as_a <gcall *> (stmt)); 2884 2885 case GIMPLE_COND: 2886 { 2887 if (!cfun->can_throw_non_call_exceptions) 2888 return false; 2889 gcond *cond = as_a <gcond *> (stmt); 2890 tree lhs = gimple_cond_lhs (cond); 2891 return operation_could_trap_p (gimple_cond_code (cond), 2892 FLOAT_TYPE_P (TREE_TYPE (lhs)), 2893 false, NULL_TREE); 2894 } 2895 2896 case GIMPLE_ASSIGN: 2897 if (!cfun->can_throw_non_call_exceptions 2898 || gimple_clobber_p (stmt)) 2899 return false; 2900 return stmt_could_throw_1_p (as_a <gassign *> (stmt)); 2901 2902 case GIMPLE_ASM: 2903 if (!cfun->can_throw_non_call_exceptions) 2904 return false; 2905 return gimple_asm_volatile_p (as_a <gasm *> (stmt)); 2906 2907 default: 2908 return false; 2909 } 2910 } 2911 2912 2913 /* Return true if expression T could throw an exception. */ 2914 2915 bool 2916 tree_could_throw_p (tree t) 2917 { 2918 if (!flag_exceptions) 2919 return false; 2920 if (TREE_CODE (t) == MODIFY_EXPR) 2921 { 2922 if (cfun->can_throw_non_call_exceptions 2923 && tree_could_trap_p (TREE_OPERAND (t, 0))) 2924 return true; 2925 t = TREE_OPERAND (t, 1); 2926 } 2927 2928 if (TREE_CODE (t) == WITH_SIZE_EXPR) 2929 t = TREE_OPERAND (t, 0); 2930 if (TREE_CODE (t) == CALL_EXPR) 2931 return (call_expr_flags (t) & ECF_NOTHROW) == 0; 2932 if (cfun->can_throw_non_call_exceptions) 2933 return tree_could_trap_p (t); 2934 return false; 2935 } 2936 2937 /* Return true if STMT can throw an exception that is not caught within 2938 the current function (CFUN). */ 2939 2940 bool 2941 stmt_can_throw_external (gimple *stmt) 2942 { 2943 int lp_nr; 2944 2945 if (!stmt_could_throw_p (stmt)) 2946 return false; 2947 2948 lp_nr = lookup_stmt_eh_lp (stmt); 2949 return lp_nr == 0; 2950 } 2951 2952 /* Return true if STMT can throw an exception that is caught within 2953 the current function (CFUN). */ 2954 2955 bool 2956 stmt_can_throw_internal (gimple *stmt) 2957 { 2958 int lp_nr; 2959 2960 if (!stmt_could_throw_p (stmt)) 2961 return false; 2962 2963 lp_nr = lookup_stmt_eh_lp (stmt); 2964 return lp_nr > 0; 2965 } 2966 2967 /* Given a statement STMT in IFUN, if STMT can no longer throw, then 2968 remove any entry it might have from the EH table. Return true if 2969 any change was made. */ 2970 2971 bool 2972 maybe_clean_eh_stmt_fn (struct function *ifun, gimple *stmt) 2973 { 2974 if (stmt_could_throw_p (stmt)) 2975 return false; 2976 return remove_stmt_from_eh_lp_fn (ifun, stmt); 2977 } 2978 2979 /* Likewise, but always use the current function. */ 2980 2981 bool 2982 maybe_clean_eh_stmt (gimple *stmt) 2983 { 2984 return maybe_clean_eh_stmt_fn (cfun, stmt); 2985 } 2986 2987 /* Given a statement OLD_STMT and a new statement NEW_STMT that has replaced 2988 OLD_STMT in the function, remove OLD_STMT from the EH table and put NEW_STMT 2989 in the table if it should be in there. Return TRUE if a replacement was 2990 done that my require an EH edge purge. */ 2991 2992 bool 2993 maybe_clean_or_replace_eh_stmt (gimple *old_stmt, gimple *new_stmt) 2994 { 2995 int lp_nr = lookup_stmt_eh_lp (old_stmt); 2996 2997 if (lp_nr != 0) 2998 { 2999 bool new_stmt_could_throw = stmt_could_throw_p (new_stmt); 3000 3001 if (new_stmt == old_stmt && new_stmt_could_throw) 3002 return false; 3003 3004 remove_stmt_from_eh_lp (old_stmt); 3005 if (new_stmt_could_throw) 3006 { 3007 add_stmt_to_eh_lp (new_stmt, lp_nr); 3008 return false; 3009 } 3010 else 3011 return true; 3012 } 3013 3014 return false; 3015 } 3016 3017 /* Given a statement OLD_STMT in OLD_FUN and a duplicate statement NEW_STMT 3018 in NEW_FUN, copy the EH table data from OLD_STMT to NEW_STMT. The MAP 3019 operand is the return value of duplicate_eh_regions. */ 3020 3021 bool 3022 maybe_duplicate_eh_stmt_fn (struct function *new_fun, gimple *new_stmt, 3023 struct function *old_fun, gimple *old_stmt, 3024 hash_map<void *, void *> *map, 3025 int default_lp_nr) 3026 { 3027 int old_lp_nr, new_lp_nr; 3028 3029 if (!stmt_could_throw_p (new_stmt)) 3030 return false; 3031 3032 old_lp_nr = lookup_stmt_eh_lp_fn (old_fun, old_stmt); 3033 if (old_lp_nr == 0) 3034 { 3035 if (default_lp_nr == 0) 3036 return false; 3037 new_lp_nr = default_lp_nr; 3038 } 3039 else if (old_lp_nr > 0) 3040 { 3041 eh_landing_pad old_lp, new_lp; 3042 3043 old_lp = (*old_fun->eh->lp_array)[old_lp_nr]; 3044 new_lp = static_cast<eh_landing_pad> (*map->get (old_lp)); 3045 new_lp_nr = new_lp->index; 3046 } 3047 else 3048 { 3049 eh_region old_r, new_r; 3050 3051 old_r = (*old_fun->eh->region_array)[-old_lp_nr]; 3052 new_r = static_cast<eh_region> (*map->get (old_r)); 3053 new_lp_nr = -new_r->index; 3054 } 3055 3056 add_stmt_to_eh_lp_fn (new_fun, new_stmt, new_lp_nr); 3057 return true; 3058 } 3059 3060 /* Similar, but both OLD_STMT and NEW_STMT are within the current function, 3061 and thus no remapping is required. */ 3062 3063 bool 3064 maybe_duplicate_eh_stmt (gimple *new_stmt, gimple *old_stmt) 3065 { 3066 int lp_nr; 3067 3068 if (!stmt_could_throw_p (new_stmt)) 3069 return false; 3070 3071 lp_nr = lookup_stmt_eh_lp (old_stmt); 3072 if (lp_nr == 0) 3073 return false; 3074 3075 add_stmt_to_eh_lp (new_stmt, lp_nr); 3076 return true; 3077 } 3078 3079 /* Returns TRUE if oneh and twoh are exception handlers (gimple_try_cleanup of 3080 GIMPLE_TRY) that are similar enough to be considered the same. Currently 3081 this only handles handlers consisting of a single call, as that's the 3082 important case for C++: a destructor call for a particular object showing 3083 up in multiple handlers. */ 3084 3085 static bool 3086 same_handler_p (gimple_seq oneh, gimple_seq twoh) 3087 { 3088 gimple_stmt_iterator gsi; 3089 gimple *ones, *twos; 3090 unsigned int ai; 3091 3092 gsi = gsi_start (oneh); 3093 if (!gsi_one_before_end_p (gsi)) 3094 return false; 3095 ones = gsi_stmt (gsi); 3096 3097 gsi = gsi_start (twoh); 3098 if (!gsi_one_before_end_p (gsi)) 3099 return false; 3100 twos = gsi_stmt (gsi); 3101 3102 if (!is_gimple_call (ones) 3103 || !is_gimple_call (twos) 3104 || gimple_call_lhs (ones) 3105 || gimple_call_lhs (twos) 3106 || gimple_call_chain (ones) 3107 || gimple_call_chain (twos) 3108 || !gimple_call_same_target_p (ones, twos) 3109 || gimple_call_num_args (ones) != gimple_call_num_args (twos)) 3110 return false; 3111 3112 for (ai = 0; ai < gimple_call_num_args (ones); ++ai) 3113 if (!operand_equal_p (gimple_call_arg (ones, ai), 3114 gimple_call_arg (twos, ai), 0)) 3115 return false; 3116 3117 return true; 3118 } 3119 3120 /* Optimize 3121 try { A() } finally { try { ~B() } catch { ~A() } } 3122 try { ... } finally { ~A() } 3123 into 3124 try { A() } catch { ~B() } 3125 try { ~B() ... } finally { ~A() } 3126 3127 This occurs frequently in C++, where A is a local variable and B is a 3128 temporary used in the initializer for A. */ 3129 3130 static void 3131 optimize_double_finally (gtry *one, gtry *two) 3132 { 3133 gimple *oneh; 3134 gimple_stmt_iterator gsi; 3135 gimple_seq cleanup; 3136 3137 cleanup = gimple_try_cleanup (one); 3138 gsi = gsi_start (cleanup); 3139 if (!gsi_one_before_end_p (gsi)) 3140 return; 3141 3142 oneh = gsi_stmt (gsi); 3143 if (gimple_code (oneh) != GIMPLE_TRY 3144 || gimple_try_kind (oneh) != GIMPLE_TRY_CATCH) 3145 return; 3146 3147 if (same_handler_p (gimple_try_cleanup (oneh), gimple_try_cleanup (two))) 3148 { 3149 gimple_seq seq = gimple_try_eval (oneh); 3150 3151 gimple_try_set_cleanup (one, seq); 3152 gimple_try_set_kind (one, GIMPLE_TRY_CATCH); 3153 seq = copy_gimple_seq_and_replace_locals (seq); 3154 gimple_seq_add_seq (&seq, gimple_try_eval (two)); 3155 gimple_try_set_eval (two, seq); 3156 } 3157 } 3158 3159 /* Perform EH refactoring optimizations that are simpler to do when code 3160 flow has been lowered but EH structures haven't. */ 3161 3162 static void 3163 refactor_eh_r (gimple_seq seq) 3164 { 3165 gimple_stmt_iterator gsi; 3166 gimple *one, *two; 3167 3168 one = NULL; 3169 two = NULL; 3170 gsi = gsi_start (seq); 3171 while (1) 3172 { 3173 one = two; 3174 if (gsi_end_p (gsi)) 3175 two = NULL; 3176 else 3177 two = gsi_stmt (gsi); 3178 if (one && two) 3179 if (gtry *try_one = dyn_cast <gtry *> (one)) 3180 if (gtry *try_two = dyn_cast <gtry *> (two)) 3181 if (gimple_try_kind (try_one) == GIMPLE_TRY_FINALLY 3182 && gimple_try_kind (try_two) == GIMPLE_TRY_FINALLY) 3183 optimize_double_finally (try_one, try_two); 3184 if (one) 3185 switch (gimple_code (one)) 3186 { 3187 case GIMPLE_TRY: 3188 refactor_eh_r (gimple_try_eval (one)); 3189 refactor_eh_r (gimple_try_cleanup (one)); 3190 break; 3191 case GIMPLE_CATCH: 3192 refactor_eh_r (gimple_catch_handler (as_a <gcatch *> (one))); 3193 break; 3194 case GIMPLE_EH_FILTER: 3195 refactor_eh_r (gimple_eh_filter_failure (one)); 3196 break; 3197 case GIMPLE_EH_ELSE: 3198 { 3199 geh_else *eh_else_stmt = as_a <geh_else *> (one); 3200 refactor_eh_r (gimple_eh_else_n_body (eh_else_stmt)); 3201 refactor_eh_r (gimple_eh_else_e_body (eh_else_stmt)); 3202 } 3203 break; 3204 default: 3205 break; 3206 } 3207 if (two) 3208 gsi_next (&gsi); 3209 else 3210 break; 3211 } 3212 } 3213 3214 namespace { 3215 3216 const pass_data pass_data_refactor_eh = 3217 { 3218 GIMPLE_PASS, /* type */ 3219 "ehopt", /* name */ 3220 OPTGROUP_NONE, /* optinfo_flags */ 3221 TV_TREE_EH, /* tv_id */ 3222 PROP_gimple_lcf, /* properties_required */ 3223 0, /* properties_provided */ 3224 0, /* properties_destroyed */ 3225 0, /* todo_flags_start */ 3226 0, /* todo_flags_finish */ 3227 }; 3228 3229 class pass_refactor_eh : public gimple_opt_pass 3230 { 3231 public: 3232 pass_refactor_eh (gcc::context *ctxt) 3233 : gimple_opt_pass (pass_data_refactor_eh, ctxt) 3234 {} 3235 3236 /* opt_pass methods: */ 3237 virtual bool gate (function *) { return flag_exceptions != 0; } 3238 virtual unsigned int execute (function *) 3239 { 3240 refactor_eh_r (gimple_body (current_function_decl)); 3241 return 0; 3242 } 3243 3244 }; // class pass_refactor_eh 3245 3246 } // anon namespace 3247 3248 gimple_opt_pass * 3249 make_pass_refactor_eh (gcc::context *ctxt) 3250 { 3251 return new pass_refactor_eh (ctxt); 3252 } 3253 3254 /* At the end of gimple optimization, we can lower RESX. */ 3255 3256 static bool 3257 lower_resx (basic_block bb, gresx *stmt, 3258 hash_map<eh_region, tree> *mnt_map) 3259 { 3260 int lp_nr; 3261 eh_region src_r, dst_r; 3262 gimple_stmt_iterator gsi; 3263 gimple *x; 3264 tree fn, src_nr; 3265 bool ret = false; 3266 3267 lp_nr = lookup_stmt_eh_lp (stmt); 3268 if (lp_nr != 0) 3269 dst_r = get_eh_region_from_lp_number (lp_nr); 3270 else 3271 dst_r = NULL; 3272 3273 src_r = get_eh_region_from_number (gimple_resx_region (stmt)); 3274 gsi = gsi_last_bb (bb); 3275 3276 if (src_r == NULL) 3277 { 3278 /* We can wind up with no source region when pass_cleanup_eh shows 3279 that there are no entries into an eh region and deletes it, but 3280 then the block that contains the resx isn't removed. This can 3281 happen without optimization when the switch statement created by 3282 lower_try_finally_switch isn't simplified to remove the eh case. 3283 3284 Resolve this by expanding the resx node to an abort. */ 3285 3286 fn = builtin_decl_implicit (BUILT_IN_TRAP); 3287 x = gimple_build_call (fn, 0); 3288 gsi_insert_before (&gsi, x, GSI_SAME_STMT); 3289 3290 while (EDGE_COUNT (bb->succs) > 0) 3291 remove_edge (EDGE_SUCC (bb, 0)); 3292 } 3293 else if (dst_r) 3294 { 3295 /* When we have a destination region, we resolve this by copying 3296 the excptr and filter values into place, and changing the edge 3297 to immediately after the landing pad. */ 3298 edge e; 3299 3300 if (lp_nr < 0) 3301 { 3302 basic_block new_bb; 3303 tree lab; 3304 3305 /* We are resuming into a MUST_NOT_CALL region. Expand a call to 3306 the failure decl into a new block, if needed. */ 3307 gcc_assert (dst_r->type == ERT_MUST_NOT_THROW); 3308 3309 tree *slot = mnt_map->get (dst_r); 3310 if (slot == NULL) 3311 { 3312 gimple_stmt_iterator gsi2; 3313 3314 new_bb = create_empty_bb (bb); 3315 new_bb->count = bb->count; 3316 add_bb_to_loop (new_bb, bb->loop_father); 3317 lab = gimple_block_label (new_bb); 3318 gsi2 = gsi_start_bb (new_bb); 3319 3320 fn = dst_r->u.must_not_throw.failure_decl; 3321 x = gimple_build_call (fn, 0); 3322 gimple_set_location (x, dst_r->u.must_not_throw.failure_loc); 3323 gsi_insert_after (&gsi2, x, GSI_CONTINUE_LINKING); 3324 3325 mnt_map->put (dst_r, lab); 3326 } 3327 else 3328 { 3329 lab = *slot; 3330 new_bb = label_to_block (lab); 3331 } 3332 3333 gcc_assert (EDGE_COUNT (bb->succs) == 0); 3334 e = make_single_succ_edge (bb, new_bb, EDGE_FALLTHRU); 3335 } 3336 else 3337 { 3338 edge_iterator ei; 3339 tree dst_nr = build_int_cst (integer_type_node, dst_r->index); 3340 3341 fn = builtin_decl_implicit (BUILT_IN_EH_COPY_VALUES); 3342 src_nr = build_int_cst (integer_type_node, src_r->index); 3343 x = gimple_build_call (fn, 2, dst_nr, src_nr); 3344 gsi_insert_before (&gsi, x, GSI_SAME_STMT); 3345 3346 /* Update the flags for the outgoing edge. */ 3347 e = single_succ_edge (bb); 3348 gcc_assert (e->flags & EDGE_EH); 3349 e->flags = (e->flags & ~EDGE_EH) | EDGE_FALLTHRU; 3350 e->probability = profile_probability::always (); 3351 3352 /* If there are no more EH users of the landing pad, delete it. */ 3353 FOR_EACH_EDGE (e, ei, e->dest->preds) 3354 if (e->flags & EDGE_EH) 3355 break; 3356 if (e == NULL) 3357 { 3358 eh_landing_pad lp = get_eh_landing_pad_from_number (lp_nr); 3359 remove_eh_landing_pad (lp); 3360 } 3361 } 3362 3363 ret = true; 3364 } 3365 else 3366 { 3367 tree var; 3368 3369 /* When we don't have a destination region, this exception escapes 3370 up the call chain. We resolve this by generating a call to the 3371 _Unwind_Resume library function. */ 3372 3373 /* The ARM EABI redefines _Unwind_Resume as __cxa_end_cleanup 3374 with no arguments for C++. Check for that. */ 3375 if (src_r->use_cxa_end_cleanup) 3376 { 3377 fn = builtin_decl_implicit (BUILT_IN_CXA_END_CLEANUP); 3378 x = gimple_build_call (fn, 0); 3379 gsi_insert_before (&gsi, x, GSI_SAME_STMT); 3380 } 3381 else 3382 { 3383 fn = builtin_decl_implicit (BUILT_IN_EH_POINTER); 3384 src_nr = build_int_cst (integer_type_node, src_r->index); 3385 x = gimple_build_call (fn, 1, src_nr); 3386 var = create_tmp_var (ptr_type_node); 3387 var = make_ssa_name (var, x); 3388 gimple_call_set_lhs (x, var); 3389 gsi_insert_before (&gsi, x, GSI_SAME_STMT); 3390 3391 /* When exception handling is delegated to a caller function, we 3392 have to guarantee that shadow memory variables living on stack 3393 will be cleaner before control is given to a parent function. */ 3394 if (sanitize_flags_p (SANITIZE_ADDRESS)) 3395 { 3396 tree decl 3397 = builtin_decl_implicit (BUILT_IN_ASAN_HANDLE_NO_RETURN); 3398 gimple *g = gimple_build_call (decl, 0); 3399 gimple_set_location (g, gimple_location (stmt)); 3400 gsi_insert_before (&gsi, g, GSI_SAME_STMT); 3401 } 3402 3403 fn = builtin_decl_implicit (BUILT_IN_UNWIND_RESUME); 3404 x = gimple_build_call (fn, 1, var); 3405 gsi_insert_before (&gsi, x, GSI_SAME_STMT); 3406 } 3407 3408 gcc_assert (EDGE_COUNT (bb->succs) == 0); 3409 } 3410 3411 gsi_remove (&gsi, true); 3412 3413 return ret; 3414 } 3415 3416 namespace { 3417 3418 const pass_data pass_data_lower_resx = 3419 { 3420 GIMPLE_PASS, /* type */ 3421 "resx", /* name */ 3422 OPTGROUP_NONE, /* optinfo_flags */ 3423 TV_TREE_EH, /* tv_id */ 3424 PROP_gimple_lcf, /* properties_required */ 3425 0, /* properties_provided */ 3426 0, /* properties_destroyed */ 3427 0, /* todo_flags_start */ 3428 0, /* todo_flags_finish */ 3429 }; 3430 3431 class pass_lower_resx : public gimple_opt_pass 3432 { 3433 public: 3434 pass_lower_resx (gcc::context *ctxt) 3435 : gimple_opt_pass (pass_data_lower_resx, ctxt) 3436 {} 3437 3438 /* opt_pass methods: */ 3439 virtual bool gate (function *) { return flag_exceptions != 0; } 3440 virtual unsigned int execute (function *); 3441 3442 }; // class pass_lower_resx 3443 3444 unsigned 3445 pass_lower_resx::execute (function *fun) 3446 { 3447 basic_block bb; 3448 bool dominance_invalidated = false; 3449 bool any_rewritten = false; 3450 3451 hash_map<eh_region, tree> mnt_map; 3452 3453 FOR_EACH_BB_FN (bb, fun) 3454 { 3455 gimple *last = last_stmt (bb); 3456 if (last && is_gimple_resx (last)) 3457 { 3458 dominance_invalidated |= 3459 lower_resx (bb, as_a <gresx *> (last), &mnt_map); 3460 any_rewritten = true; 3461 } 3462 } 3463 3464 if (dominance_invalidated) 3465 { 3466 free_dominance_info (CDI_DOMINATORS); 3467 free_dominance_info (CDI_POST_DOMINATORS); 3468 } 3469 3470 return any_rewritten ? TODO_update_ssa_only_virtuals : 0; 3471 } 3472 3473 } // anon namespace 3474 3475 gimple_opt_pass * 3476 make_pass_lower_resx (gcc::context *ctxt) 3477 { 3478 return new pass_lower_resx (ctxt); 3479 } 3480 3481 /* Try to optimize var = {v} {CLOBBER} stmts followed just by 3482 external throw. */ 3483 3484 static void 3485 optimize_clobbers (basic_block bb) 3486 { 3487 gimple_stmt_iterator gsi = gsi_last_bb (bb); 3488 bool any_clobbers = false; 3489 bool seen_stack_restore = false; 3490 edge_iterator ei; 3491 edge e; 3492 3493 /* Only optimize anything if the bb contains at least one clobber, 3494 ends with resx (checked by caller), optionally contains some 3495 debug stmts or labels, or at most one __builtin_stack_restore 3496 call, and has an incoming EH edge. */ 3497 for (gsi_prev (&gsi); !gsi_end_p (gsi); gsi_prev (&gsi)) 3498 { 3499 gimple *stmt = gsi_stmt (gsi); 3500 if (is_gimple_debug (stmt)) 3501 continue; 3502 if (gimple_clobber_p (stmt)) 3503 { 3504 any_clobbers = true; 3505 continue; 3506 } 3507 if (!seen_stack_restore 3508 && gimple_call_builtin_p (stmt, BUILT_IN_STACK_RESTORE)) 3509 { 3510 seen_stack_restore = true; 3511 continue; 3512 } 3513 if (gimple_code (stmt) == GIMPLE_LABEL) 3514 break; 3515 return; 3516 } 3517 if (!any_clobbers) 3518 return; 3519 FOR_EACH_EDGE (e, ei, bb->preds) 3520 if (e->flags & EDGE_EH) 3521 break; 3522 if (e == NULL) 3523 return; 3524 gsi = gsi_last_bb (bb); 3525 for (gsi_prev (&gsi); !gsi_end_p (gsi); gsi_prev (&gsi)) 3526 { 3527 gimple *stmt = gsi_stmt (gsi); 3528 if (!gimple_clobber_p (stmt)) 3529 continue; 3530 unlink_stmt_vdef (stmt); 3531 gsi_remove (&gsi, true); 3532 release_defs (stmt); 3533 } 3534 } 3535 3536 /* Try to sink var = {v} {CLOBBER} stmts followed just by 3537 internal throw to successor BB. */ 3538 3539 static int 3540 sink_clobbers (basic_block bb) 3541 { 3542 edge e; 3543 edge_iterator ei; 3544 gimple_stmt_iterator gsi, dgsi; 3545 basic_block succbb; 3546 bool any_clobbers = false; 3547 unsigned todo = 0; 3548 3549 /* Only optimize if BB has a single EH successor and 3550 all predecessor edges are EH too. */ 3551 if (!single_succ_p (bb) 3552 || (single_succ_edge (bb)->flags & EDGE_EH) == 0) 3553 return 0; 3554 3555 FOR_EACH_EDGE (e, ei, bb->preds) 3556 { 3557 if ((e->flags & EDGE_EH) == 0) 3558 return 0; 3559 } 3560 3561 /* And BB contains only CLOBBER stmts before the final 3562 RESX. */ 3563 gsi = gsi_last_bb (bb); 3564 for (gsi_prev (&gsi); !gsi_end_p (gsi); gsi_prev (&gsi)) 3565 { 3566 gimple *stmt = gsi_stmt (gsi); 3567 if (is_gimple_debug (stmt)) 3568 continue; 3569 if (gimple_code (stmt) == GIMPLE_LABEL) 3570 break; 3571 if (!gimple_clobber_p (stmt)) 3572 return 0; 3573 any_clobbers = true; 3574 } 3575 if (!any_clobbers) 3576 return 0; 3577 3578 edge succe = single_succ_edge (bb); 3579 succbb = succe->dest; 3580 3581 /* See if there is a virtual PHI node to take an updated virtual 3582 operand from. */ 3583 gphi *vphi = NULL; 3584 tree vuse = NULL_TREE; 3585 for (gphi_iterator gpi = gsi_start_phis (succbb); 3586 !gsi_end_p (gpi); gsi_next (&gpi)) 3587 { 3588 tree res = gimple_phi_result (gpi.phi ()); 3589 if (virtual_operand_p (res)) 3590 { 3591 vphi = gpi.phi (); 3592 vuse = res; 3593 break; 3594 } 3595 } 3596 3597 dgsi = gsi_after_labels (succbb); 3598 gsi = gsi_last_bb (bb); 3599 for (gsi_prev (&gsi); !gsi_end_p (gsi); gsi_prev (&gsi)) 3600 { 3601 gimple *stmt = gsi_stmt (gsi); 3602 tree lhs; 3603 if (is_gimple_debug (stmt)) 3604 continue; 3605 if (gimple_code (stmt) == GIMPLE_LABEL) 3606 break; 3607 lhs = gimple_assign_lhs (stmt); 3608 /* Unfortunately we don't have dominance info updated at this 3609 point, so checking if 3610 dominated_by_p (CDI_DOMINATORS, succbb, 3611 gimple_bb (SSA_NAME_DEF_STMT (TREE_OPERAND (lhs, 0))) 3612 would be too costly. Thus, avoid sinking any clobbers that 3613 refer to non-(D) SSA_NAMEs. */ 3614 if (TREE_CODE (lhs) == MEM_REF 3615 && TREE_CODE (TREE_OPERAND (lhs, 0)) == SSA_NAME 3616 && !SSA_NAME_IS_DEFAULT_DEF (TREE_OPERAND (lhs, 0))) 3617 { 3618 unlink_stmt_vdef (stmt); 3619 gsi_remove (&gsi, true); 3620 release_defs (stmt); 3621 continue; 3622 } 3623 3624 /* As we do not change stmt order when sinking across a 3625 forwarder edge we can keep virtual operands in place. */ 3626 gsi_remove (&gsi, false); 3627 gsi_insert_before (&dgsi, stmt, GSI_NEW_STMT); 3628 3629 /* But adjust virtual operands if we sunk across a PHI node. */ 3630 if (vuse) 3631 { 3632 gimple *use_stmt; 3633 imm_use_iterator iter; 3634 use_operand_p use_p; 3635 FOR_EACH_IMM_USE_STMT (use_stmt, iter, vuse) 3636 FOR_EACH_IMM_USE_ON_STMT (use_p, iter) 3637 SET_USE (use_p, gimple_vdef (stmt)); 3638 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (vuse)) 3639 { 3640 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (gimple_vdef (stmt)) = 1; 3641 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (vuse) = 0; 3642 } 3643 /* Adjust the incoming virtual operand. */ 3644 SET_USE (PHI_ARG_DEF_PTR_FROM_EDGE (vphi, succe), gimple_vuse (stmt)); 3645 SET_USE (gimple_vuse_op (stmt), vuse); 3646 } 3647 /* If there isn't a single predecessor but no virtual PHI node 3648 arrange for virtual operands to be renamed. */ 3649 else if (gimple_vuse_op (stmt) != NULL_USE_OPERAND_P 3650 && !single_pred_p (succbb)) 3651 { 3652 /* In this case there will be no use of the VDEF of this stmt. 3653 ??? Unless this is a secondary opportunity and we have not 3654 removed unreachable blocks yet, so we cannot assert this. 3655 Which also means we will end up renaming too many times. */ 3656 SET_USE (gimple_vuse_op (stmt), gimple_vop (cfun)); 3657 mark_virtual_operands_for_renaming (cfun); 3658 todo |= TODO_update_ssa_only_virtuals; 3659 } 3660 } 3661 3662 return todo; 3663 } 3664 3665 /* At the end of inlining, we can lower EH_DISPATCH. Return true when 3666 we have found some duplicate labels and removed some edges. */ 3667 3668 static bool 3669 lower_eh_dispatch (basic_block src, geh_dispatch *stmt) 3670 { 3671 gimple_stmt_iterator gsi; 3672 int region_nr; 3673 eh_region r; 3674 tree filter, fn; 3675 gimple *x; 3676 bool redirected = false; 3677 3678 region_nr = gimple_eh_dispatch_region (stmt); 3679 r = get_eh_region_from_number (region_nr); 3680 3681 gsi = gsi_last_bb (src); 3682 3683 switch (r->type) 3684 { 3685 case ERT_TRY: 3686 { 3687 auto_vec<tree> labels; 3688 tree default_label = NULL; 3689 eh_catch c; 3690 edge_iterator ei; 3691 edge e; 3692 hash_set<tree> seen_values; 3693 3694 /* Collect the labels for a switch. Zero the post_landing_pad 3695 field becase we'll no longer have anything keeping these labels 3696 in existence and the optimizer will be free to merge these 3697 blocks at will. */ 3698 for (c = r->u.eh_try.first_catch; c ; c = c->next_catch) 3699 { 3700 tree tp_node, flt_node, lab = c->label; 3701 bool have_label = false; 3702 3703 c->label = NULL; 3704 tp_node = c->type_list; 3705 flt_node = c->filter_list; 3706 3707 if (tp_node == NULL) 3708 { 3709 default_label = lab; 3710 break; 3711 } 3712 do 3713 { 3714 /* Filter out duplicate labels that arise when this handler 3715 is shadowed by an earlier one. When no labels are 3716 attached to the handler anymore, we remove 3717 the corresponding edge and then we delete unreachable 3718 blocks at the end of this pass. */ 3719 if (! seen_values.contains (TREE_VALUE (flt_node))) 3720 { 3721 tree t = build_case_label (TREE_VALUE (flt_node), 3722 NULL, lab); 3723 labels.safe_push (t); 3724 seen_values.add (TREE_VALUE (flt_node)); 3725 have_label = true; 3726 } 3727 3728 tp_node = TREE_CHAIN (tp_node); 3729 flt_node = TREE_CHAIN (flt_node); 3730 } 3731 while (tp_node); 3732 if (! have_label) 3733 { 3734 remove_edge (find_edge (src, label_to_block (lab))); 3735 redirected = true; 3736 } 3737 } 3738 3739 /* Clean up the edge flags. */ 3740 FOR_EACH_EDGE (e, ei, src->succs) 3741 { 3742 if (e->flags & EDGE_FALLTHRU) 3743 { 3744 /* If there was no catch-all, use the fallthru edge. */ 3745 if (default_label == NULL) 3746 default_label = gimple_block_label (e->dest); 3747 e->flags &= ~EDGE_FALLTHRU; 3748 } 3749 } 3750 gcc_assert (default_label != NULL); 3751 3752 /* Don't generate a switch if there's only a default case. 3753 This is common in the form of try { A; } catch (...) { B; }. */ 3754 if (!labels.exists ()) 3755 { 3756 e = single_succ_edge (src); 3757 e->flags |= EDGE_FALLTHRU; 3758 } 3759 else 3760 { 3761 fn = builtin_decl_implicit (BUILT_IN_EH_FILTER); 3762 x = gimple_build_call (fn, 1, build_int_cst (integer_type_node, 3763 region_nr)); 3764 filter = create_tmp_var (TREE_TYPE (TREE_TYPE (fn))); 3765 filter = make_ssa_name (filter, x); 3766 gimple_call_set_lhs (x, filter); 3767 gsi_insert_before (&gsi, x, GSI_SAME_STMT); 3768 3769 /* Turn the default label into a default case. */ 3770 default_label = build_case_label (NULL, NULL, default_label); 3771 sort_case_labels (labels); 3772 3773 x = gimple_build_switch (filter, default_label, labels); 3774 gsi_insert_before (&gsi, x, GSI_SAME_STMT); 3775 } 3776 } 3777 break; 3778 3779 case ERT_ALLOWED_EXCEPTIONS: 3780 { 3781 edge b_e = BRANCH_EDGE (src); 3782 edge f_e = FALLTHRU_EDGE (src); 3783 3784 fn = builtin_decl_implicit (BUILT_IN_EH_FILTER); 3785 x = gimple_build_call (fn, 1, build_int_cst (integer_type_node, 3786 region_nr)); 3787 filter = create_tmp_var (TREE_TYPE (TREE_TYPE (fn))); 3788 filter = make_ssa_name (filter, x); 3789 gimple_call_set_lhs (x, filter); 3790 gsi_insert_before (&gsi, x, GSI_SAME_STMT); 3791 3792 r->u.allowed.label = NULL; 3793 x = gimple_build_cond (EQ_EXPR, filter, 3794 build_int_cst (TREE_TYPE (filter), 3795 r->u.allowed.filter), 3796 NULL_TREE, NULL_TREE); 3797 gsi_insert_before (&gsi, x, GSI_SAME_STMT); 3798 3799 b_e->flags = b_e->flags | EDGE_TRUE_VALUE; 3800 f_e->flags = (f_e->flags & ~EDGE_FALLTHRU) | EDGE_FALSE_VALUE; 3801 } 3802 break; 3803 3804 default: 3805 gcc_unreachable (); 3806 } 3807 3808 /* Replace the EH_DISPATCH with the SWITCH or COND generated above. */ 3809 gsi_remove (&gsi, true); 3810 return redirected; 3811 } 3812 3813 namespace { 3814 3815 const pass_data pass_data_lower_eh_dispatch = 3816 { 3817 GIMPLE_PASS, /* type */ 3818 "ehdisp", /* name */ 3819 OPTGROUP_NONE, /* optinfo_flags */ 3820 TV_TREE_EH, /* tv_id */ 3821 PROP_gimple_lcf, /* properties_required */ 3822 0, /* properties_provided */ 3823 0, /* properties_destroyed */ 3824 0, /* todo_flags_start */ 3825 0, /* todo_flags_finish */ 3826 }; 3827 3828 class pass_lower_eh_dispatch : public gimple_opt_pass 3829 { 3830 public: 3831 pass_lower_eh_dispatch (gcc::context *ctxt) 3832 : gimple_opt_pass (pass_data_lower_eh_dispatch, ctxt) 3833 {} 3834 3835 /* opt_pass methods: */ 3836 virtual bool gate (function *fun) { return fun->eh->region_tree != NULL; } 3837 virtual unsigned int execute (function *); 3838 3839 }; // class pass_lower_eh_dispatch 3840 3841 unsigned 3842 pass_lower_eh_dispatch::execute (function *fun) 3843 { 3844 basic_block bb; 3845 int flags = 0; 3846 bool redirected = false; 3847 3848 assign_filter_values (); 3849 3850 FOR_EACH_BB_FN (bb, fun) 3851 { 3852 gimple *last = last_stmt (bb); 3853 if (last == NULL) 3854 continue; 3855 if (gimple_code (last) == GIMPLE_EH_DISPATCH) 3856 { 3857 redirected |= lower_eh_dispatch (bb, 3858 as_a <geh_dispatch *> (last)); 3859 flags |= TODO_update_ssa_only_virtuals; 3860 } 3861 else if (gimple_code (last) == GIMPLE_RESX) 3862 { 3863 if (stmt_can_throw_external (last)) 3864 optimize_clobbers (bb); 3865 else 3866 flags |= sink_clobbers (bb); 3867 } 3868 } 3869 3870 if (redirected) 3871 { 3872 free_dominance_info (CDI_DOMINATORS); 3873 delete_unreachable_blocks (); 3874 } 3875 return flags; 3876 } 3877 3878 } // anon namespace 3879 3880 gimple_opt_pass * 3881 make_pass_lower_eh_dispatch (gcc::context *ctxt) 3882 { 3883 return new pass_lower_eh_dispatch (ctxt); 3884 } 3885 3886 /* Walk statements, see what regions and, optionally, landing pads 3887 are really referenced. 3888 3889 Returns in R_REACHABLEP an sbitmap with bits set for reachable regions, 3890 and in LP_REACHABLE an sbitmap with bits set for reachable landing pads. 3891 3892 Passing NULL for LP_REACHABLE is valid, in this case only reachable 3893 regions are marked. 3894 3895 The caller is responsible for freeing the returned sbitmaps. */ 3896 3897 static void 3898 mark_reachable_handlers (sbitmap *r_reachablep, sbitmap *lp_reachablep) 3899 { 3900 sbitmap r_reachable, lp_reachable; 3901 basic_block bb; 3902 bool mark_landing_pads = (lp_reachablep != NULL); 3903 gcc_checking_assert (r_reachablep != NULL); 3904 3905 r_reachable = sbitmap_alloc (cfun->eh->region_array->length ()); 3906 bitmap_clear (r_reachable); 3907 *r_reachablep = r_reachable; 3908 3909 if (mark_landing_pads) 3910 { 3911 lp_reachable = sbitmap_alloc (cfun->eh->lp_array->length ()); 3912 bitmap_clear (lp_reachable); 3913 *lp_reachablep = lp_reachable; 3914 } 3915 else 3916 lp_reachable = NULL; 3917 3918 FOR_EACH_BB_FN (bb, cfun) 3919 { 3920 gimple_stmt_iterator gsi; 3921 3922 for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi)) 3923 { 3924 gimple *stmt = gsi_stmt (gsi); 3925 3926 if (mark_landing_pads) 3927 { 3928 int lp_nr = lookup_stmt_eh_lp (stmt); 3929 3930 /* Negative LP numbers are MUST_NOT_THROW regions which 3931 are not considered BB enders. */ 3932 if (lp_nr < 0) 3933 bitmap_set_bit (r_reachable, -lp_nr); 3934 3935 /* Positive LP numbers are real landing pads, and BB enders. */ 3936 else if (lp_nr > 0) 3937 { 3938 gcc_assert (gsi_one_before_end_p (gsi)); 3939 eh_region region = get_eh_region_from_lp_number (lp_nr); 3940 bitmap_set_bit (r_reachable, region->index); 3941 bitmap_set_bit (lp_reachable, lp_nr); 3942 } 3943 } 3944 3945 /* Avoid removing regions referenced from RESX/EH_DISPATCH. */ 3946 switch (gimple_code (stmt)) 3947 { 3948 case GIMPLE_RESX: 3949 bitmap_set_bit (r_reachable, 3950 gimple_resx_region (as_a <gresx *> (stmt))); 3951 break; 3952 case GIMPLE_EH_DISPATCH: 3953 bitmap_set_bit (r_reachable, 3954 gimple_eh_dispatch_region ( 3955 as_a <geh_dispatch *> (stmt))); 3956 break; 3957 case GIMPLE_CALL: 3958 if (gimple_call_builtin_p (stmt, BUILT_IN_EH_COPY_VALUES)) 3959 for (int i = 0; i < 2; ++i) 3960 { 3961 tree rt = gimple_call_arg (stmt, i); 3962 HOST_WIDE_INT ri = tree_to_shwi (rt); 3963 3964 gcc_assert (ri == (int)ri); 3965 bitmap_set_bit (r_reachable, ri); 3966 } 3967 break; 3968 default: 3969 break; 3970 } 3971 } 3972 } 3973 } 3974 3975 /* Remove unreachable handlers and unreachable landing pads. */ 3976 3977 static void 3978 remove_unreachable_handlers (void) 3979 { 3980 sbitmap r_reachable, lp_reachable; 3981 eh_region region; 3982 eh_landing_pad lp; 3983 unsigned i; 3984 3985 mark_reachable_handlers (&r_reachable, &lp_reachable); 3986 3987 if (dump_file) 3988 { 3989 fprintf (dump_file, "Before removal of unreachable regions:\n"); 3990 dump_eh_tree (dump_file, cfun); 3991 fprintf (dump_file, "Reachable regions: "); 3992 dump_bitmap_file (dump_file, r_reachable); 3993 fprintf (dump_file, "Reachable landing pads: "); 3994 dump_bitmap_file (dump_file, lp_reachable); 3995 } 3996 3997 if (dump_file) 3998 { 3999 FOR_EACH_VEC_SAFE_ELT (cfun->eh->region_array, i, region) 4000 if (region && !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 FOR_EACH_VEC_SAFE_ELT (cfun->eh->lp_array, i, lp) 4009 if (lp && !bitmap_bit_p (lp_reachable, lp->index)) 4010 { 4011 if (dump_file) 4012 fprintf (dump_file, 4013 "Removing unreachable landing pad %d\n", 4014 lp->index); 4015 remove_eh_landing_pad (lp); 4016 } 4017 4018 if (dump_file) 4019 { 4020 fprintf (dump_file, "\n\nAfter removal of unreachable regions:\n"); 4021 dump_eh_tree (dump_file, cfun); 4022 fprintf (dump_file, "\n\n"); 4023 } 4024 4025 sbitmap_free (r_reachable); 4026 sbitmap_free (lp_reachable); 4027 4028 if (flag_checking) 4029 verify_eh_tree (cfun); 4030 } 4031 4032 /* Remove unreachable handlers if any landing pads have been removed after 4033 last ehcleanup pass (due to gimple_purge_dead_eh_edges). */ 4034 4035 void 4036 maybe_remove_unreachable_handlers (void) 4037 { 4038 eh_landing_pad lp; 4039 unsigned i; 4040 4041 if (cfun->eh == NULL) 4042 return; 4043 4044 FOR_EACH_VEC_SAFE_ELT (cfun->eh->lp_array, i, lp) 4045 if (lp && lp->post_landing_pad) 4046 { 4047 if (label_to_block (lp->post_landing_pad) == NULL) 4048 { 4049 remove_unreachable_handlers (); 4050 return; 4051 } 4052 } 4053 } 4054 4055 /* Remove regions that do not have landing pads. This assumes 4056 that remove_unreachable_handlers has already been run, and 4057 that we've just manipulated the landing pads since then. 4058 4059 Preserve regions with landing pads and regions that prevent 4060 exceptions from propagating further, even if these regions 4061 are not reachable. */ 4062 4063 static void 4064 remove_unreachable_handlers_no_lp (void) 4065 { 4066 eh_region region; 4067 sbitmap r_reachable; 4068 unsigned i; 4069 4070 mark_reachable_handlers (&r_reachable, /*lp_reachablep=*/NULL); 4071 4072 FOR_EACH_VEC_SAFE_ELT (cfun->eh->region_array, i, region) 4073 { 4074 if (! region) 4075 continue; 4076 4077 if (region->landing_pads != NULL 4078 || region->type == ERT_MUST_NOT_THROW) 4079 bitmap_set_bit (r_reachable, region->index); 4080 4081 if (dump_file 4082 && !bitmap_bit_p (r_reachable, region->index)) 4083 fprintf (dump_file, 4084 "Removing unreachable region %d\n", 4085 region->index); 4086 } 4087 4088 remove_unreachable_eh_regions (r_reachable); 4089 4090 sbitmap_free (r_reachable); 4091 } 4092 4093 /* Undo critical edge splitting on an EH landing pad. Earlier, we 4094 optimisticaly split all sorts of edges, including EH edges. The 4095 optimization passes in between may not have needed them; if not, 4096 we should undo the split. 4097 4098 Recognize this case by having one EH edge incoming to the BB and 4099 one normal edge outgoing; BB should be empty apart from the 4100 post_landing_pad label. 4101 4102 Note that this is slightly different from the empty handler case 4103 handled by cleanup_empty_eh, in that the actual handler may yet 4104 have actual code but the landing pad has been separated from the 4105 handler. As such, cleanup_empty_eh relies on this transformation 4106 having been done first. */ 4107 4108 static bool 4109 unsplit_eh (eh_landing_pad lp) 4110 { 4111 basic_block bb = label_to_block (lp->post_landing_pad); 4112 gimple_stmt_iterator gsi; 4113 edge e_in, e_out; 4114 4115 /* Quickly check the edge counts on BB for singularity. */ 4116 if (!single_pred_p (bb) || !single_succ_p (bb)) 4117 return false; 4118 e_in = single_pred_edge (bb); 4119 e_out = single_succ_edge (bb); 4120 4121 /* Input edge must be EH and output edge must be normal. */ 4122 if ((e_in->flags & EDGE_EH) == 0 || (e_out->flags & EDGE_EH) != 0) 4123 return false; 4124 4125 /* The block must be empty except for the labels and debug insns. */ 4126 gsi = gsi_after_labels (bb); 4127 if (!gsi_end_p (gsi) && is_gimple_debug (gsi_stmt (gsi))) 4128 gsi_next_nondebug (&gsi); 4129 if (!gsi_end_p (gsi)) 4130 return false; 4131 4132 /* The destination block must not already have a landing pad 4133 for a different region. */ 4134 for (gsi = gsi_start_bb (e_out->dest); !gsi_end_p (gsi); gsi_next (&gsi)) 4135 { 4136 glabel *label_stmt = dyn_cast <glabel *> (gsi_stmt (gsi)); 4137 tree lab; 4138 int lp_nr; 4139 4140 if (!label_stmt) 4141 break; 4142 lab = gimple_label_label (label_stmt); 4143 lp_nr = EH_LANDING_PAD_NR (lab); 4144 if (lp_nr && get_eh_region_from_lp_number (lp_nr) != lp->region) 4145 return false; 4146 } 4147 4148 /* The new destination block must not already be a destination of 4149 the source block, lest we merge fallthru and eh edges and get 4150 all sorts of confused. */ 4151 if (find_edge (e_in->src, e_out->dest)) 4152 return false; 4153 4154 /* ??? We can get degenerate phis due to cfg cleanups. I would have 4155 thought this should have been cleaned up by a phicprop pass, but 4156 that doesn't appear to handle virtuals. Propagate by hand. */ 4157 if (!gimple_seq_empty_p (phi_nodes (bb))) 4158 { 4159 for (gphi_iterator gpi = gsi_start_phis (bb); !gsi_end_p (gpi); ) 4160 { 4161 gimple *use_stmt; 4162 gphi *phi = gpi.phi (); 4163 tree lhs = gimple_phi_result (phi); 4164 tree rhs = gimple_phi_arg_def (phi, 0); 4165 use_operand_p use_p; 4166 imm_use_iterator iter; 4167 4168 FOR_EACH_IMM_USE_STMT (use_stmt, iter, lhs) 4169 { 4170 FOR_EACH_IMM_USE_ON_STMT (use_p, iter) 4171 SET_USE (use_p, rhs); 4172 } 4173 4174 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (lhs)) 4175 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (rhs) = 1; 4176 4177 remove_phi_node (&gpi, true); 4178 } 4179 } 4180 4181 if (dump_file && (dump_flags & TDF_DETAILS)) 4182 fprintf (dump_file, "Unsplit EH landing pad %d to block %i.\n", 4183 lp->index, e_out->dest->index); 4184 4185 /* Redirect the edge. Since redirect_eh_edge_1 expects to be moving 4186 a successor edge, humor it. But do the real CFG change with the 4187 predecessor of E_OUT in order to preserve the ordering of arguments 4188 to the PHI nodes in E_OUT->DEST. */ 4189 redirect_eh_edge_1 (e_in, e_out->dest, false); 4190 redirect_edge_pred (e_out, e_in->src); 4191 e_out->flags = e_in->flags; 4192 e_out->probability = e_in->probability; 4193 remove_edge (e_in); 4194 4195 return true; 4196 } 4197 4198 /* Examine each landing pad block and see if it matches unsplit_eh. */ 4199 4200 static bool 4201 unsplit_all_eh (void) 4202 { 4203 bool changed = false; 4204 eh_landing_pad lp; 4205 int i; 4206 4207 for (i = 1; vec_safe_iterate (cfun->eh->lp_array, i, &lp); ++i) 4208 if (lp) 4209 changed |= unsplit_eh (lp); 4210 4211 return changed; 4212 } 4213 4214 /* A subroutine of cleanup_empty_eh. Redirect all EH edges incoming 4215 to OLD_BB to NEW_BB; return true on success, false on failure. 4216 4217 OLD_BB_OUT is the edge into NEW_BB from OLD_BB, so if we miss any 4218 PHI variables from OLD_BB we can pick them up from OLD_BB_OUT. 4219 Virtual PHIs may be deleted and marked for renaming. */ 4220 4221 static bool 4222 cleanup_empty_eh_merge_phis (basic_block new_bb, basic_block old_bb, 4223 edge old_bb_out, bool change_region) 4224 { 4225 gphi_iterator ngsi, ogsi; 4226 edge_iterator ei; 4227 edge e; 4228 bitmap ophi_handled; 4229 4230 /* The destination block must not be a regular successor for any 4231 of the preds of the landing pad. Thus, avoid turning 4232 <..> 4233 | \ EH 4234 | <..> 4235 | / 4236 <..> 4237 into 4238 <..> 4239 | | EH 4240 <..> 4241 which CFG verification would choke on. See PR45172 and PR51089. */ 4242 FOR_EACH_EDGE (e, ei, old_bb->preds) 4243 if (find_edge (e->src, new_bb)) 4244 return false; 4245 4246 FOR_EACH_EDGE (e, ei, old_bb->preds) 4247 redirect_edge_var_map_clear (e); 4248 4249 ophi_handled = BITMAP_ALLOC (NULL); 4250 4251 /* First, iterate through the PHIs on NEW_BB and set up the edge_var_map 4252 for the edges we're going to move. */ 4253 for (ngsi = gsi_start_phis (new_bb); !gsi_end_p (ngsi); gsi_next (&ngsi)) 4254 { 4255 gphi *ophi, *nphi = ngsi.phi (); 4256 tree nresult, nop; 4257 4258 nresult = gimple_phi_result (nphi); 4259 nop = gimple_phi_arg_def (nphi, old_bb_out->dest_idx); 4260 4261 /* Find the corresponding PHI in OLD_BB so we can forward-propagate 4262 the source ssa_name. */ 4263 ophi = NULL; 4264 for (ogsi = gsi_start_phis (old_bb); !gsi_end_p (ogsi); gsi_next (&ogsi)) 4265 { 4266 ophi = ogsi.phi (); 4267 if (gimple_phi_result (ophi) == nop) 4268 break; 4269 ophi = NULL; 4270 } 4271 4272 /* If we did find the corresponding PHI, copy those inputs. */ 4273 if (ophi) 4274 { 4275 /* If NOP is used somewhere else beyond phis in new_bb, give up. */ 4276 if (!has_single_use (nop)) 4277 { 4278 imm_use_iterator imm_iter; 4279 use_operand_p use_p; 4280 4281 FOR_EACH_IMM_USE_FAST (use_p, imm_iter, nop) 4282 { 4283 if (!gimple_debug_bind_p (USE_STMT (use_p)) 4284 && (gimple_code (USE_STMT (use_p)) != GIMPLE_PHI 4285 || gimple_bb (USE_STMT (use_p)) != new_bb)) 4286 goto fail; 4287 } 4288 } 4289 bitmap_set_bit (ophi_handled, SSA_NAME_VERSION (nop)); 4290 FOR_EACH_EDGE (e, ei, old_bb->preds) 4291 { 4292 location_t oloc; 4293 tree oop; 4294 4295 if ((e->flags & EDGE_EH) == 0) 4296 continue; 4297 oop = gimple_phi_arg_def (ophi, e->dest_idx); 4298 oloc = gimple_phi_arg_location (ophi, e->dest_idx); 4299 redirect_edge_var_map_add (e, nresult, oop, oloc); 4300 } 4301 } 4302 /* If we didn't find the PHI, if it's a real variable or a VOP, we know 4303 from the fact that OLD_BB is tree_empty_eh_handler_p that the 4304 variable is unchanged from input to the block and we can simply 4305 re-use the input to NEW_BB from the OLD_BB_OUT edge. */ 4306 else 4307 { 4308 location_t nloc 4309 = gimple_phi_arg_location (nphi, old_bb_out->dest_idx); 4310 FOR_EACH_EDGE (e, ei, old_bb->preds) 4311 redirect_edge_var_map_add (e, nresult, nop, nloc); 4312 } 4313 } 4314 4315 /* Second, verify that all PHIs from OLD_BB have been handled. If not, 4316 we don't know what values from the other edges into NEW_BB to use. */ 4317 for (ogsi = gsi_start_phis (old_bb); !gsi_end_p (ogsi); gsi_next (&ogsi)) 4318 { 4319 gphi *ophi = ogsi.phi (); 4320 tree oresult = gimple_phi_result (ophi); 4321 if (!bitmap_bit_p (ophi_handled, SSA_NAME_VERSION (oresult))) 4322 goto fail; 4323 } 4324 4325 /* Finally, move the edges and update the PHIs. */ 4326 for (ei = ei_start (old_bb->preds); (e = ei_safe_edge (ei)); ) 4327 if (e->flags & EDGE_EH) 4328 { 4329 /* ??? CFG manipluation routines do not try to update loop 4330 form on edge redirection. Do so manually here for now. */ 4331 /* If we redirect a loop entry or latch edge that will either create 4332 a multiple entry loop or rotate the loop. If the loops merge 4333 we may have created a loop with multiple latches. 4334 All of this isn't easily fixed thus cancel the affected loop 4335 and mark the other loop as possibly having multiple latches. */ 4336 if (e->dest == e->dest->loop_father->header) 4337 { 4338 mark_loop_for_removal (e->dest->loop_father); 4339 new_bb->loop_father->latch = NULL; 4340 loops_state_set (LOOPS_MAY_HAVE_MULTIPLE_LATCHES); 4341 } 4342 redirect_eh_edge_1 (e, new_bb, change_region); 4343 redirect_edge_succ (e, new_bb); 4344 flush_pending_stmts (e); 4345 } 4346 else 4347 ei_next (&ei); 4348 4349 BITMAP_FREE (ophi_handled); 4350 return true; 4351 4352 fail: 4353 FOR_EACH_EDGE (e, ei, old_bb->preds) 4354 redirect_edge_var_map_clear (e); 4355 BITMAP_FREE (ophi_handled); 4356 return false; 4357 } 4358 4359 /* A subroutine of cleanup_empty_eh. Move a landing pad LP from its 4360 old region to NEW_REGION at BB. */ 4361 4362 static void 4363 cleanup_empty_eh_move_lp (basic_block bb, edge e_out, 4364 eh_landing_pad lp, eh_region new_region) 4365 { 4366 gimple_stmt_iterator gsi; 4367 eh_landing_pad *pp; 4368 4369 for (pp = &lp->region->landing_pads; *pp != lp; pp = &(*pp)->next_lp) 4370 continue; 4371 *pp = lp->next_lp; 4372 4373 lp->region = new_region; 4374 lp->next_lp = new_region->landing_pads; 4375 new_region->landing_pads = lp; 4376 4377 /* Delete the RESX that was matched within the empty handler block. */ 4378 gsi = gsi_last_bb (bb); 4379 unlink_stmt_vdef (gsi_stmt (gsi)); 4380 gsi_remove (&gsi, true); 4381 4382 /* Clean up E_OUT for the fallthru. */ 4383 e_out->flags = (e_out->flags & ~EDGE_EH) | EDGE_FALLTHRU; 4384 e_out->probability = profile_probability::always (); 4385 } 4386 4387 /* A subroutine of cleanup_empty_eh. Handle more complex cases of 4388 unsplitting than unsplit_eh was prepared to handle, e.g. when 4389 multiple incoming edges and phis are involved. */ 4390 4391 static bool 4392 cleanup_empty_eh_unsplit (basic_block bb, edge e_out, eh_landing_pad lp) 4393 { 4394 gimple_stmt_iterator gsi; 4395 tree lab; 4396 4397 /* We really ought not have totally lost everything following 4398 a landing pad label. Given that BB is empty, there had better 4399 be a successor. */ 4400 gcc_assert (e_out != NULL); 4401 4402 /* The destination block must not already have a landing pad 4403 for a different region. */ 4404 lab = NULL; 4405 for (gsi = gsi_start_bb (e_out->dest); !gsi_end_p (gsi); gsi_next (&gsi)) 4406 { 4407 glabel *stmt = dyn_cast <glabel *> (gsi_stmt (gsi)); 4408 int lp_nr; 4409 4410 if (!stmt) 4411 break; 4412 lab = gimple_label_label (stmt); 4413 lp_nr = EH_LANDING_PAD_NR (lab); 4414 if (lp_nr && get_eh_region_from_lp_number (lp_nr) != lp->region) 4415 return false; 4416 } 4417 4418 /* Attempt to move the PHIs into the successor block. */ 4419 if (cleanup_empty_eh_merge_phis (e_out->dest, bb, e_out, false)) 4420 { 4421 if (dump_file && (dump_flags & TDF_DETAILS)) 4422 fprintf (dump_file, 4423 "Unsplit EH landing pad %d to block %i " 4424 "(via cleanup_empty_eh).\n", 4425 lp->index, e_out->dest->index); 4426 return true; 4427 } 4428 4429 return false; 4430 } 4431 4432 /* Return true if edge E_FIRST is part of an empty infinite loop 4433 or leads to such a loop through a series of single successor 4434 empty bbs. */ 4435 4436 static bool 4437 infinite_empty_loop_p (edge e_first) 4438 { 4439 bool inf_loop = false; 4440 edge e; 4441 4442 if (e_first->dest == e_first->src) 4443 return true; 4444 4445 e_first->src->aux = (void *) 1; 4446 for (e = e_first; single_succ_p (e->dest); e = single_succ_edge (e->dest)) 4447 { 4448 gimple_stmt_iterator gsi; 4449 if (e->dest->aux) 4450 { 4451 inf_loop = true; 4452 break; 4453 } 4454 e->dest->aux = (void *) 1; 4455 gsi = gsi_after_labels (e->dest); 4456 if (!gsi_end_p (gsi) && is_gimple_debug (gsi_stmt (gsi))) 4457 gsi_next_nondebug (&gsi); 4458 if (!gsi_end_p (gsi)) 4459 break; 4460 } 4461 e_first->src->aux = NULL; 4462 for (e = e_first; e->dest->aux; e = single_succ_edge (e->dest)) 4463 e->dest->aux = NULL; 4464 4465 return inf_loop; 4466 } 4467 4468 /* Examine the block associated with LP to determine if it's an empty 4469 handler for its EH region. If so, attempt to redirect EH edges to 4470 an outer region. Return true the CFG was updated in any way. This 4471 is similar to jump forwarding, just across EH edges. */ 4472 4473 static bool 4474 cleanup_empty_eh (eh_landing_pad lp) 4475 { 4476 basic_block bb = label_to_block (lp->post_landing_pad); 4477 gimple_stmt_iterator gsi; 4478 gimple *resx; 4479 eh_region new_region; 4480 edge_iterator ei; 4481 edge e, e_out; 4482 bool has_non_eh_pred; 4483 bool ret = false; 4484 int new_lp_nr; 4485 4486 /* There can be zero or one edges out of BB. This is the quickest test. */ 4487 switch (EDGE_COUNT (bb->succs)) 4488 { 4489 case 0: 4490 e_out = NULL; 4491 break; 4492 case 1: 4493 e_out = single_succ_edge (bb); 4494 break; 4495 default: 4496 return false; 4497 } 4498 4499 gsi = gsi_last_nondebug_bb (bb); 4500 resx = gsi_stmt (gsi); 4501 if (resx && is_gimple_resx (resx)) 4502 { 4503 if (stmt_can_throw_external (resx)) 4504 optimize_clobbers (bb); 4505 else if (sink_clobbers (bb)) 4506 ret = true; 4507 } 4508 4509 gsi = gsi_after_labels (bb); 4510 4511 /* Make sure to skip debug statements. */ 4512 if (!gsi_end_p (gsi) && is_gimple_debug (gsi_stmt (gsi))) 4513 gsi_next_nondebug (&gsi); 4514 4515 /* If the block is totally empty, look for more unsplitting cases. */ 4516 if (gsi_end_p (gsi)) 4517 { 4518 /* For the degenerate case of an infinite loop bail out. 4519 If bb has no successors and is totally empty, which can happen e.g. 4520 because of incorrect noreturn attribute, bail out too. */ 4521 if (e_out == NULL 4522 || infinite_empty_loop_p (e_out)) 4523 return ret; 4524 4525 return ret | cleanup_empty_eh_unsplit (bb, e_out, lp); 4526 } 4527 4528 /* The block should consist only of a single RESX statement, modulo a 4529 preceding call to __builtin_stack_restore if there is no outgoing 4530 edge, since the call can be eliminated in this case. */ 4531 resx = gsi_stmt (gsi); 4532 if (!e_out && gimple_call_builtin_p (resx, BUILT_IN_STACK_RESTORE)) 4533 { 4534 gsi_next_nondebug (&gsi); 4535 resx = gsi_stmt (gsi); 4536 } 4537 if (!is_gimple_resx (resx)) 4538 return ret; 4539 gcc_assert (gsi_one_nondebug_before_end_p (gsi)); 4540 4541 /* Determine if there are non-EH edges, or resx edges into the handler. */ 4542 has_non_eh_pred = false; 4543 FOR_EACH_EDGE (e, ei, bb->preds) 4544 if (!(e->flags & EDGE_EH)) 4545 has_non_eh_pred = true; 4546 4547 /* Find the handler that's outer of the empty handler by looking at 4548 where the RESX instruction was vectored. */ 4549 new_lp_nr = lookup_stmt_eh_lp (resx); 4550 new_region = get_eh_region_from_lp_number (new_lp_nr); 4551 4552 /* If there's no destination region within the current function, 4553 redirection is trivial via removing the throwing statements from 4554 the EH region, removing the EH edges, and allowing the block 4555 to go unreachable. */ 4556 if (new_region == NULL) 4557 { 4558 gcc_assert (e_out == NULL); 4559 for (ei = ei_start (bb->preds); (e = ei_safe_edge (ei)); ) 4560 if (e->flags & EDGE_EH) 4561 { 4562 gimple *stmt = last_stmt (e->src); 4563 remove_stmt_from_eh_lp (stmt); 4564 remove_edge (e); 4565 } 4566 else 4567 ei_next (&ei); 4568 goto succeed; 4569 } 4570 4571 /* If the destination region is a MUST_NOT_THROW, allow the runtime 4572 to handle the abort and allow the blocks to go unreachable. */ 4573 if (new_region->type == ERT_MUST_NOT_THROW) 4574 { 4575 for (ei = ei_start (bb->preds); (e = ei_safe_edge (ei)); ) 4576 if (e->flags & EDGE_EH) 4577 { 4578 gimple *stmt = last_stmt (e->src); 4579 remove_stmt_from_eh_lp (stmt); 4580 add_stmt_to_eh_lp (stmt, new_lp_nr); 4581 remove_edge (e); 4582 } 4583 else 4584 ei_next (&ei); 4585 goto succeed; 4586 } 4587 4588 /* Try to redirect the EH edges and merge the PHIs into the destination 4589 landing pad block. If the merge succeeds, we'll already have redirected 4590 all the EH edges. The handler itself will go unreachable if there were 4591 no normal edges. */ 4592 if (cleanup_empty_eh_merge_phis (e_out->dest, bb, e_out, true)) 4593 goto succeed; 4594 4595 /* Finally, if all input edges are EH edges, then we can (potentially) 4596 reduce the number of transfers from the runtime by moving the landing 4597 pad from the original region to the new region. This is a win when 4598 we remove the last CLEANUP region along a particular exception 4599 propagation path. Since nothing changes except for the region with 4600 which the landing pad is associated, the PHI nodes do not need to be 4601 adjusted at all. */ 4602 if (!has_non_eh_pred) 4603 { 4604 cleanup_empty_eh_move_lp (bb, e_out, lp, new_region); 4605 if (dump_file && (dump_flags & TDF_DETAILS)) 4606 fprintf (dump_file, "Empty EH handler %i moved to EH region %i.\n", 4607 lp->index, new_region->index); 4608 4609 /* ??? The CFG didn't change, but we may have rendered the 4610 old EH region unreachable. Trigger a cleanup there. */ 4611 return true; 4612 } 4613 4614 return ret; 4615 4616 succeed: 4617 if (dump_file && (dump_flags & TDF_DETAILS)) 4618 fprintf (dump_file, "Empty EH handler %i removed.\n", lp->index); 4619 remove_eh_landing_pad (lp); 4620 return true; 4621 } 4622 4623 /* Do a post-order traversal of the EH region tree. Examine each 4624 post_landing_pad block and see if we can eliminate it as empty. */ 4625 4626 static bool 4627 cleanup_all_empty_eh (void) 4628 { 4629 bool changed = false; 4630 eh_landing_pad lp; 4631 int i; 4632 4633 for (i = 1; vec_safe_iterate (cfun->eh->lp_array, i, &lp); ++i) 4634 if (lp) 4635 changed |= cleanup_empty_eh (lp); 4636 4637 return changed; 4638 } 4639 4640 /* Perform cleanups and lowering of exception handling 4641 1) cleanups regions with handlers doing nothing are optimized out 4642 2) MUST_NOT_THROW regions that became dead because of 1) are optimized out 4643 3) Info about regions that are containing instructions, and regions 4644 reachable via local EH edges is collected 4645 4) Eh tree is pruned for regions no longer necessary. 4646 4647 TODO: Push MUST_NOT_THROW regions to the root of the EH tree. 4648 Unify those that have the same failure decl and locus. 4649 */ 4650 4651 static unsigned int 4652 execute_cleanup_eh_1 (void) 4653 { 4654 /* Do this first: unsplit_all_eh and cleanup_all_empty_eh can die 4655 looking up unreachable landing pads. */ 4656 remove_unreachable_handlers (); 4657 4658 /* Watch out for the region tree vanishing due to all unreachable. */ 4659 if (cfun->eh->region_tree) 4660 { 4661 bool changed = false; 4662 4663 if (optimize) 4664 changed |= unsplit_all_eh (); 4665 changed |= cleanup_all_empty_eh (); 4666 4667 if (changed) 4668 { 4669 free_dominance_info (CDI_DOMINATORS); 4670 free_dominance_info (CDI_POST_DOMINATORS); 4671 4672 /* We delayed all basic block deletion, as we may have performed 4673 cleanups on EH edges while non-EH edges were still present. */ 4674 delete_unreachable_blocks (); 4675 4676 /* We manipulated the landing pads. Remove any region that no 4677 longer has a landing pad. */ 4678 remove_unreachable_handlers_no_lp (); 4679 4680 return TODO_cleanup_cfg | TODO_update_ssa_only_virtuals; 4681 } 4682 } 4683 4684 return 0; 4685 } 4686 4687 namespace { 4688 4689 const pass_data pass_data_cleanup_eh = 4690 { 4691 GIMPLE_PASS, /* type */ 4692 "ehcleanup", /* name */ 4693 OPTGROUP_NONE, /* optinfo_flags */ 4694 TV_TREE_EH, /* tv_id */ 4695 PROP_gimple_lcf, /* properties_required */ 4696 0, /* properties_provided */ 4697 0, /* properties_destroyed */ 4698 0, /* todo_flags_start */ 4699 0, /* todo_flags_finish */ 4700 }; 4701 4702 class pass_cleanup_eh : public gimple_opt_pass 4703 { 4704 public: 4705 pass_cleanup_eh (gcc::context *ctxt) 4706 : gimple_opt_pass (pass_data_cleanup_eh, ctxt) 4707 {} 4708 4709 /* opt_pass methods: */ 4710 opt_pass * clone () { return new pass_cleanup_eh (m_ctxt); } 4711 virtual bool gate (function *fun) 4712 { 4713 return fun->eh != NULL && fun->eh->region_tree != NULL; 4714 } 4715 4716 virtual unsigned int execute (function *); 4717 4718 }; // class pass_cleanup_eh 4719 4720 unsigned int 4721 pass_cleanup_eh::execute (function *fun) 4722 { 4723 int ret = execute_cleanup_eh_1 (); 4724 4725 /* If the function no longer needs an EH personality routine 4726 clear it. This exposes cross-language inlining opportunities 4727 and avoids references to a never defined personality routine. */ 4728 if (DECL_FUNCTION_PERSONALITY (current_function_decl) 4729 && function_needs_eh_personality (fun) != eh_personality_lang) 4730 DECL_FUNCTION_PERSONALITY (current_function_decl) = NULL_TREE; 4731 4732 return ret; 4733 } 4734 4735 } // anon namespace 4736 4737 gimple_opt_pass * 4738 make_pass_cleanup_eh (gcc::context *ctxt) 4739 { 4740 return new pass_cleanup_eh (ctxt); 4741 } 4742 4743 /* Verify that BB containing STMT as the last statement, has precisely the 4744 edge that make_eh_edges would create. */ 4745 4746 DEBUG_FUNCTION bool 4747 verify_eh_edges (gimple *stmt) 4748 { 4749 basic_block bb = gimple_bb (stmt); 4750 eh_landing_pad lp = NULL; 4751 int lp_nr; 4752 edge_iterator ei; 4753 edge e, eh_edge; 4754 4755 lp_nr = lookup_stmt_eh_lp (stmt); 4756 if (lp_nr > 0) 4757 lp = get_eh_landing_pad_from_number (lp_nr); 4758 4759 eh_edge = NULL; 4760 FOR_EACH_EDGE (e, ei, bb->succs) 4761 { 4762 if (e->flags & EDGE_EH) 4763 { 4764 if (eh_edge) 4765 { 4766 error ("BB %i has multiple EH edges", bb->index); 4767 return true; 4768 } 4769 else 4770 eh_edge = e; 4771 } 4772 } 4773 4774 if (lp == NULL) 4775 { 4776 if (eh_edge) 4777 { 4778 error ("BB %i can not throw but has an EH edge", bb->index); 4779 return true; 4780 } 4781 return false; 4782 } 4783 4784 if (!stmt_could_throw_p (stmt)) 4785 { 4786 error ("BB %i last statement has incorrectly set lp", bb->index); 4787 return true; 4788 } 4789 4790 if (eh_edge == NULL) 4791 { 4792 error ("BB %i is missing an EH edge", bb->index); 4793 return true; 4794 } 4795 4796 if (eh_edge->dest != label_to_block (lp->post_landing_pad)) 4797 { 4798 error ("Incorrect EH edge %i->%i", bb->index, eh_edge->dest->index); 4799 return true; 4800 } 4801 4802 return false; 4803 } 4804 4805 /* Similarly, but handle GIMPLE_EH_DISPATCH specifically. */ 4806 4807 DEBUG_FUNCTION bool 4808 verify_eh_dispatch_edge (geh_dispatch *stmt) 4809 { 4810 eh_region r; 4811 eh_catch c; 4812 basic_block src, dst; 4813 bool want_fallthru = true; 4814 edge_iterator ei; 4815 edge e, fall_edge; 4816 4817 r = get_eh_region_from_number (gimple_eh_dispatch_region (stmt)); 4818 src = gimple_bb (stmt); 4819 4820 FOR_EACH_EDGE (e, ei, src->succs) 4821 gcc_assert (e->aux == NULL); 4822 4823 switch (r->type) 4824 { 4825 case ERT_TRY: 4826 for (c = r->u.eh_try.first_catch; c ; c = c->next_catch) 4827 { 4828 dst = label_to_block (c->label); 4829 e = find_edge (src, dst); 4830 if (e == NULL) 4831 { 4832 error ("BB %i is missing an edge", src->index); 4833 return true; 4834 } 4835 e->aux = (void *)e; 4836 4837 /* A catch-all handler doesn't have a fallthru. */ 4838 if (c->type_list == NULL) 4839 { 4840 want_fallthru = false; 4841 break; 4842 } 4843 } 4844 break; 4845 4846 case ERT_ALLOWED_EXCEPTIONS: 4847 dst = label_to_block (r->u.allowed.label); 4848 e = find_edge (src, dst); 4849 if (e == NULL) 4850 { 4851 error ("BB %i is missing an edge", src->index); 4852 return true; 4853 } 4854 e->aux = (void *)e; 4855 break; 4856 4857 default: 4858 gcc_unreachable (); 4859 } 4860 4861 fall_edge = NULL; 4862 FOR_EACH_EDGE (e, ei, src->succs) 4863 { 4864 if (e->flags & EDGE_FALLTHRU) 4865 { 4866 if (fall_edge != NULL) 4867 { 4868 error ("BB %i too many fallthru edges", src->index); 4869 return true; 4870 } 4871 fall_edge = e; 4872 } 4873 else if (e->aux) 4874 e->aux = NULL; 4875 else 4876 { 4877 error ("BB %i has incorrect edge", src->index); 4878 return true; 4879 } 4880 } 4881 if ((fall_edge != NULL) ^ want_fallthru) 4882 { 4883 error ("BB %i has incorrect fallthru edge", src->index); 4884 return true; 4885 } 4886 4887 return false; 4888 } 4889