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