1 /* Exception handling semantics and decomposition for trees.
2 Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011
3 Free Software Foundation, Inc.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 3, or (at your option)
12 GCC is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING3. If not see
19 <http://www.gnu.org/licenses/>. */
23 #include "coretypes.h"
29 #include "pointer-set.h"
30 #include "tree-flow.h"
31 #include "tree-dump.h"
32 #include "tree-inline.h"
33 #include "tree-iterator.h"
34 #include "tree-pass.h"
36 #include "langhooks.h"
38 #include "diagnostic-core.h"
42 /* In some instances a tree and a gimple need to be stored in a same table,
43 i.e. in hash tables. This is a structure to do this. */
44 typedef union {tree *tp; tree t; gimple g;} treemple;
46 /* Nonzero if we are using EH to handle cleanups. */
47 static int using_eh_for_cleanups_p = 0;
50 using_eh_for_cleanups (void)
52 using_eh_for_cleanups_p = 1;
55 /* Misc functions used in this file. */
57 /* Compare and hash for any structure which begins with a canonical
58 pointer. Assumes all pointers are interchangeable, which is sort
59 of already assumed by gcc elsewhere IIRC. */
62 struct_ptr_eq (const void *a, const void *b)
64 const void * const * x = (const void * const *) a;
65 const void * const * y = (const void * const *) b;
70 struct_ptr_hash (const void *a)
72 const void * const * x = (const void * const *) a;
73 return (size_t)*x >> 4;
77 /* Remember and lookup EH landing pad data for arbitrary statements.
78 Really this means any statement that could_throw_p. We could
79 stuff this information into the stmt_ann data structure, but:
81 (1) We absolutely rely on this information being kept until
82 we get to rtl. Once we're done with lowering here, if we lose
83 the information there's no way to recover it!
85 (2) There are many more statements that *cannot* throw as
86 compared to those that can. We should be saving some amount
87 of space by only allocating memory for those that can throw. */
89 /* Add statement T in function IFUN to landing pad NUM. */
92 add_stmt_to_eh_lp_fn (struct function *ifun, gimple t, int num)
94 struct throw_stmt_node *n;
97 gcc_assert (num != 0);
99 n = ggc_alloc_throw_stmt_node ();
103 if (!get_eh_throw_stmt_table (ifun))
104 set_eh_throw_stmt_table (ifun, htab_create_ggc (31, struct_ptr_hash,
108 slot = htab_find_slot (get_eh_throw_stmt_table (ifun), n, INSERT);
113 /* Add statement T in the current function (cfun) to EH landing pad NUM. */
116 add_stmt_to_eh_lp (gimple t, int num)
118 add_stmt_to_eh_lp_fn (cfun, t, num);
121 /* Add statement T to the single EH landing pad in REGION. */
124 record_stmt_eh_region (eh_region region, gimple t)
128 if (region->type == ERT_MUST_NOT_THROW)
129 add_stmt_to_eh_lp_fn (cfun, t, -region->index);
132 eh_landing_pad lp = region->landing_pads;
134 lp = gen_eh_landing_pad (region);
136 gcc_assert (lp->next_lp == NULL);
137 add_stmt_to_eh_lp_fn (cfun, t, lp->index);
142 /* Remove statement T in function IFUN from its EH landing pad. */
145 remove_stmt_from_eh_lp_fn (struct function *ifun, gimple t)
147 struct throw_stmt_node dummy;
150 if (!get_eh_throw_stmt_table (ifun))
154 slot = htab_find_slot (get_eh_throw_stmt_table (ifun), &dummy,
158 htab_clear_slot (get_eh_throw_stmt_table (ifun), slot);
166 /* Remove statement T in the current function (cfun) from its
170 remove_stmt_from_eh_lp (gimple t)
172 return remove_stmt_from_eh_lp_fn (cfun, t);
175 /* Determine if statement T is inside an EH region in function IFUN.
176 Positive numbers indicate a landing pad index; negative numbers
177 indicate a MUST_NOT_THROW region index; zero indicates that the
178 statement is not recorded in the region table. */
181 lookup_stmt_eh_lp_fn (struct function *ifun, gimple t)
183 struct throw_stmt_node *p, n;
185 if (ifun->eh->throw_stmt_table == NULL)
189 p = (struct throw_stmt_node *) htab_find (ifun->eh->throw_stmt_table, &n);
190 return p ? p->lp_nr : 0;
193 /* Likewise, but always use the current function. */
196 lookup_stmt_eh_lp (gimple t)
198 /* We can get called from initialized data when -fnon-call-exceptions
199 is on; prevent crash. */
202 return lookup_stmt_eh_lp_fn (cfun, t);
205 /* First pass of EH node decomposition. Build up a tree of GIMPLE_TRY_FINALLY
206 nodes and LABEL_DECL nodes. We will use this during the second phase to
207 determine if a goto leaves the body of a TRY_FINALLY_EXPR node. */
209 struct finally_tree_node
211 /* When storing a GIMPLE_TRY, we have to record a gimple. However
212 when deciding whether a GOTO to a certain LABEL_DECL (which is a
213 tree) leaves the TRY block, its necessary to record a tree in
214 this field. Thus a treemple is used. */
219 /* Note that this table is *not* marked GTY. It is short-lived. */
220 static htab_t finally_tree;
223 record_in_finally_tree (treemple child, gimple parent)
225 struct finally_tree_node *n;
228 n = XNEW (struct finally_tree_node);
232 slot = htab_find_slot (finally_tree, n, INSERT);
238 collect_finally_tree (gimple stmt, gimple region);
240 /* Go through the gimple sequence. Works with collect_finally_tree to
241 record all GIMPLE_LABEL and GIMPLE_TRY statements. */
244 collect_finally_tree_1 (gimple_seq seq, gimple region)
246 gimple_stmt_iterator gsi;
248 for (gsi = gsi_start (seq); !gsi_end_p (gsi); gsi_next (&gsi))
249 collect_finally_tree (gsi_stmt (gsi), region);
253 collect_finally_tree (gimple stmt, gimple region)
257 switch (gimple_code (stmt))
260 temp.t = gimple_label_label (stmt);
261 record_in_finally_tree (temp, region);
265 if (gimple_try_kind (stmt) == GIMPLE_TRY_FINALLY)
268 record_in_finally_tree (temp, region);
269 collect_finally_tree_1 (gimple_try_eval (stmt), stmt);
270 collect_finally_tree_1 (gimple_try_cleanup (stmt), region);
272 else if (gimple_try_kind (stmt) == GIMPLE_TRY_CATCH)
274 collect_finally_tree_1 (gimple_try_eval (stmt), region);
275 collect_finally_tree_1 (gimple_try_cleanup (stmt), region);
280 collect_finally_tree_1 (gimple_catch_handler (stmt), region);
283 case GIMPLE_EH_FILTER:
284 collect_finally_tree_1 (gimple_eh_filter_failure (stmt), region);
288 /* A type, a decl, or some kind of statement that we're not
289 interested in. Don't walk them. */
295 /* Use the finally tree to determine if a jump from START to TARGET
296 would leave the try_finally node that START lives in. */
299 outside_finally_tree (treemple start, gimple target)
301 struct finally_tree_node n, *p;
306 p = (struct finally_tree_node *) htab_find (finally_tree, &n);
311 while (start.g != target);
316 /* Second pass of EH node decomposition. Actually transform the GIMPLE_TRY
317 nodes into a set of gotos, magic labels, and eh regions.
318 The eh region creation is straight-forward, but frobbing all the gotos
319 and such into shape isn't. */
321 /* The sequence into which we record all EH stuff. This will be
322 placed at the end of the function when we're all done. */
323 static gimple_seq eh_seq;
325 /* Record whether an EH region contains something that can throw,
326 indexed by EH region number. */
327 static bitmap eh_region_may_contain_throw_map;
329 /* The GOTO_QUEUE is is an array of GIMPLE_GOTO and GIMPLE_RETURN
330 statements that are seen to escape this GIMPLE_TRY_FINALLY node.
331 The idea is to record a gimple statement for everything except for
332 the conditionals, which get their labels recorded. Since labels are
333 of type 'tree', we need this node to store both gimple and tree
334 objects. REPL_STMT is the sequence used to replace the goto/return
335 statement. CONT_STMT is used to store the statement that allows
336 the return/goto to jump to the original destination. */
338 struct goto_queue_node
341 gimple_seq repl_stmt;
344 /* This is used when index >= 0 to indicate that stmt is a label (as
345 opposed to a goto stmt). */
349 /* State of the world while lowering. */
353 /* What's "current" while constructing the eh region tree. These
354 correspond to variables of the same name in cfun->eh, which we
355 don't have easy access to. */
356 eh_region cur_region;
358 /* What's "current" for the purposes of __builtin_eh_pointer. For
359 a CATCH, this is the associated TRY. For an EH_FILTER, this is
360 the associated ALLOWED_EXCEPTIONS, etc. */
361 eh_region ehp_region;
363 /* Processing of TRY_FINALLY requires a bit more state. This is
364 split out into a separate structure so that we don't have to
365 copy so much when processing other nodes. */
366 struct leh_tf_state *tf;
371 /* Pointer to the GIMPLE_TRY_FINALLY node under discussion. The
372 try_finally_expr is the original GIMPLE_TRY_FINALLY. We need to retain
373 this so that outside_finally_tree can reliably reference the tree used
374 in the collect_finally_tree data structures. */
375 gimple try_finally_expr;
378 /* While lowering a top_p usually it is expanded into multiple statements,
379 thus we need the following field to store them. */
380 gimple_seq top_p_seq;
382 /* The state outside this try_finally node. */
383 struct leh_state *outer;
385 /* The exception region created for it. */
388 /* The goto queue. */
389 struct goto_queue_node *goto_queue;
390 size_t goto_queue_size;
391 size_t goto_queue_active;
393 /* Pointer map to help in searching goto_queue when it is large. */
394 struct pointer_map_t *goto_queue_map;
396 /* The set of unique labels seen as entries in the goto queue. */
397 VEC(tree,heap) *dest_array;
399 /* A label to be added at the end of the completed transformed
400 sequence. It will be set if may_fallthru was true *at one time*,
401 though subsequent transformations may have cleared that flag. */
404 /* True if it is possible to fall out the bottom of the try block.
405 Cleared if the fallthru is converted to a goto. */
408 /* True if any entry in goto_queue is a GIMPLE_RETURN. */
411 /* True if the finally block can receive an exception edge.
412 Cleared if the exception case is handled by code duplication. */
416 static gimple_seq lower_eh_must_not_throw (struct leh_state *, gimple);
418 /* Search for STMT in the goto queue. Return the replacement,
419 or null if the statement isn't in the queue. */
421 #define LARGE_GOTO_QUEUE 20
423 static void lower_eh_constructs_1 (struct leh_state *state, gimple_seq seq);
426 find_goto_replacement (struct leh_tf_state *tf, treemple stmt)
431 if (tf->goto_queue_active < LARGE_GOTO_QUEUE)
433 for (i = 0; i < tf->goto_queue_active; i++)
434 if ( tf->goto_queue[i].stmt.g == stmt.g)
435 return tf->goto_queue[i].repl_stmt;
439 /* If we have a large number of entries in the goto_queue, create a
440 pointer map and use that for searching. */
442 if (!tf->goto_queue_map)
444 tf->goto_queue_map = pointer_map_create ();
445 for (i = 0; i < tf->goto_queue_active; i++)
447 slot = pointer_map_insert (tf->goto_queue_map,
448 tf->goto_queue[i].stmt.g);
449 gcc_assert (*slot == NULL);
450 *slot = &tf->goto_queue[i];
454 slot = pointer_map_contains (tf->goto_queue_map, stmt.g);
456 return (((struct goto_queue_node *) *slot)->repl_stmt);
461 /* A subroutine of replace_goto_queue_1. Handles the sub-clauses of a
462 lowered GIMPLE_COND. If, by chance, the replacement is a simple goto,
463 then we can just splat it in, otherwise we add the new stmts immediately
464 after the GIMPLE_COND and redirect. */
467 replace_goto_queue_cond_clause (tree *tp, struct leh_tf_state *tf,
468 gimple_stmt_iterator *gsi)
473 location_t loc = gimple_location (gsi_stmt (*gsi));
476 new_seq = find_goto_replacement (tf, temp);
480 if (gimple_seq_singleton_p (new_seq)
481 && gimple_code (gimple_seq_first_stmt (new_seq)) == GIMPLE_GOTO)
483 *tp = gimple_goto_dest (gimple_seq_first_stmt (new_seq));
487 label = create_artificial_label (loc);
488 /* Set the new label for the GIMPLE_COND */
491 gsi_insert_after (gsi, gimple_build_label (label), GSI_CONTINUE_LINKING);
492 gsi_insert_seq_after (gsi, gimple_seq_copy (new_seq), GSI_CONTINUE_LINKING);
495 /* The real work of replace_goto_queue. Returns with TSI updated to
496 point to the next statement. */
498 static void replace_goto_queue_stmt_list (gimple_seq, struct leh_tf_state *);
501 replace_goto_queue_1 (gimple stmt, struct leh_tf_state *tf,
502 gimple_stmt_iterator *gsi)
508 switch (gimple_code (stmt))
513 seq = find_goto_replacement (tf, temp);
516 gsi_insert_seq_before (gsi, gimple_seq_copy (seq), GSI_SAME_STMT);
517 gsi_remove (gsi, false);
523 replace_goto_queue_cond_clause (gimple_op_ptr (stmt, 2), tf, gsi);
524 replace_goto_queue_cond_clause (gimple_op_ptr (stmt, 3), tf, gsi);
528 replace_goto_queue_stmt_list (gimple_try_eval (stmt), tf);
529 replace_goto_queue_stmt_list (gimple_try_cleanup (stmt), tf);
532 replace_goto_queue_stmt_list (gimple_catch_handler (stmt), tf);
534 case GIMPLE_EH_FILTER:
535 replace_goto_queue_stmt_list (gimple_eh_filter_failure (stmt), tf);
539 /* These won't have gotos in them. */
546 /* A subroutine of replace_goto_queue. Handles GIMPLE_SEQ. */
549 replace_goto_queue_stmt_list (gimple_seq seq, struct leh_tf_state *tf)
551 gimple_stmt_iterator gsi = gsi_start (seq);
553 while (!gsi_end_p (gsi))
554 replace_goto_queue_1 (gsi_stmt (gsi), tf, &gsi);
557 /* Replace all goto queue members. */
560 replace_goto_queue (struct leh_tf_state *tf)
562 if (tf->goto_queue_active == 0)
564 replace_goto_queue_stmt_list (tf->top_p_seq, tf);
565 replace_goto_queue_stmt_list (eh_seq, tf);
568 /* Add a new record to the goto queue contained in TF. NEW_STMT is the
569 data to be added, IS_LABEL indicates whether NEW_STMT is a label or
573 record_in_goto_queue (struct leh_tf_state *tf,
579 struct goto_queue_node *q;
581 gcc_assert (!tf->goto_queue_map);
583 active = tf->goto_queue_active;
584 size = tf->goto_queue_size;
587 size = (size ? size * 2 : 32);
588 tf->goto_queue_size = size;
590 = XRESIZEVEC (struct goto_queue_node, tf->goto_queue, size);
593 q = &tf->goto_queue[active];
594 tf->goto_queue_active = active + 1;
596 memset (q, 0, sizeof (*q));
599 q->is_label = is_label;
602 /* Record the LABEL label in the goto queue contained in TF.
606 record_in_goto_queue_label (struct leh_tf_state *tf, treemple stmt, tree label)
609 treemple temp, new_stmt;
614 /* Computed and non-local gotos do not get processed. Given
615 their nature we can neither tell whether we've escaped the
616 finally block nor redirect them if we knew. */
617 if (TREE_CODE (label) != LABEL_DECL)
620 /* No need to record gotos that don't leave the try block. */
622 if (!outside_finally_tree (temp, tf->try_finally_expr))
625 if (! tf->dest_array)
627 tf->dest_array = VEC_alloc (tree, heap, 10);
628 VEC_quick_push (tree, tf->dest_array, label);
633 int n = VEC_length (tree, tf->dest_array);
634 for (index = 0; index < n; ++index)
635 if (VEC_index (tree, tf->dest_array, index) == label)
638 VEC_safe_push (tree, heap, tf->dest_array, label);
641 /* In the case of a GOTO we want to record the destination label,
642 since with a GIMPLE_COND we have an easy access to the then/else
645 record_in_goto_queue (tf, new_stmt, index, true);
648 /* For any GIMPLE_GOTO or GIMPLE_RETURN, decide whether it leaves a try_finally
649 node, and if so record that fact in the goto queue associated with that
653 maybe_record_in_goto_queue (struct leh_state *state, gimple stmt)
655 struct leh_tf_state *tf = state->tf;
661 switch (gimple_code (stmt))
664 new_stmt.tp = gimple_op_ptr (stmt, 2);
665 record_in_goto_queue_label (tf, new_stmt, gimple_cond_true_label (stmt));
666 new_stmt.tp = gimple_op_ptr (stmt, 3);
667 record_in_goto_queue_label (tf, new_stmt, gimple_cond_false_label (stmt));
671 record_in_goto_queue_label (tf, new_stmt, gimple_goto_dest (stmt));
675 tf->may_return = true;
677 record_in_goto_queue (tf, new_stmt, -1, false);
686 #ifdef ENABLE_CHECKING
687 /* We do not process GIMPLE_SWITCHes for now. As long as the original source
688 was in fact structured, and we've not yet done jump threading, then none
689 of the labels will leave outer GIMPLE_TRY_FINALLY nodes. Verify this. */
692 verify_norecord_switch_expr (struct leh_state *state, gimple switch_expr)
694 struct leh_tf_state *tf = state->tf;
700 n = gimple_switch_num_labels (switch_expr);
702 for (i = 0; i < n; ++i)
705 tree lab = CASE_LABEL (gimple_switch_label (switch_expr, i));
707 gcc_assert (!outside_finally_tree (temp, tf->try_finally_expr));
711 #define verify_norecord_switch_expr(state, switch_expr)
714 /* Redirect a RETURN_EXPR pointed to by STMT_P to FINLAB. Place in CONT_P
715 whatever is needed to finish the return. If MOD is non-null, insert it
716 before the new branch. RETURN_VALUE_P is a cache containing a temporary
717 variable to be used in manipulating the value returned from the function. */
720 do_return_redirection (struct goto_queue_node *q, tree finlab, gimple_seq mod,
721 tree *return_value_p)
726 /* In the case of a return, the queue node must be a gimple statement. */
727 gcc_assert (!q->is_label);
729 ret_expr = gimple_return_retval (q->stmt.g);
733 if (!*return_value_p)
734 *return_value_p = ret_expr;
736 gcc_assert (*return_value_p == ret_expr);
737 q->cont_stmt = q->stmt.g;
738 /* The nasty part about redirecting the return value is that the
739 return value itself is to be computed before the FINALLY block
753 should return 0, not 1. Arrange for this to happen by copying
754 computed the return value into a local temporary. This also
755 allows us to redirect multiple return statements through the
756 same destination block; whether this is a net win or not really
757 depends, I guess, but it does make generation of the switch in
758 lower_try_finally_switch easier. */
760 if (TREE_CODE (ret_expr) == RESULT_DECL)
762 if (!*return_value_p)
763 *return_value_p = ret_expr;
765 gcc_assert (*return_value_p == ret_expr);
766 q->cont_stmt = q->stmt.g;
772 /* If we don't return a value, all return statements are the same. */
773 q->cont_stmt = q->stmt.g;
776 q->repl_stmt = gimple_seq_alloc ();
779 gimple_seq_add_seq (&q->repl_stmt, mod);
781 x = gimple_build_goto (finlab);
782 gimple_seq_add_stmt (&q->repl_stmt, x);
785 /* Similar, but easier, for GIMPLE_GOTO. */
788 do_goto_redirection (struct goto_queue_node *q, tree finlab, gimple_seq mod,
789 struct leh_tf_state *tf)
793 gcc_assert (q->is_label);
795 q->repl_stmt = gimple_seq_alloc ();
797 q->cont_stmt = gimple_build_goto (VEC_index (tree, tf->dest_array, q->index));
800 gimple_seq_add_seq (&q->repl_stmt, mod);
802 x = gimple_build_goto (finlab);
803 gimple_seq_add_stmt (&q->repl_stmt, x);
806 /* Emit a standard landing pad sequence into SEQ for REGION. */
809 emit_post_landing_pad (gimple_seq *seq, eh_region region)
811 eh_landing_pad lp = region->landing_pads;
815 lp = gen_eh_landing_pad (region);
817 lp->post_landing_pad = create_artificial_label (UNKNOWN_LOCATION);
818 EH_LANDING_PAD_NR (lp->post_landing_pad) = lp->index;
820 x = gimple_build_label (lp->post_landing_pad);
821 gimple_seq_add_stmt (seq, x);
824 /* Emit a RESX statement into SEQ for REGION. */
827 emit_resx (gimple_seq *seq, eh_region region)
829 gimple x = gimple_build_resx (region->index);
830 gimple_seq_add_stmt (seq, x);
832 record_stmt_eh_region (region->outer, x);
835 /* Emit an EH_DISPATCH statement into SEQ for REGION. */
838 emit_eh_dispatch (gimple_seq *seq, eh_region region)
840 gimple x = gimple_build_eh_dispatch (region->index);
841 gimple_seq_add_stmt (seq, x);
844 /* Note that the current EH region may contain a throw, or a
845 call to a function which itself may contain a throw. */
848 note_eh_region_may_contain_throw (eh_region region)
850 while (bitmap_set_bit (eh_region_may_contain_throw_map, region->index))
852 if (region->type == ERT_MUST_NOT_THROW)
854 region = region->outer;
860 /* Check if REGION has been marked as containing a throw. If REGION is
861 NULL, this predicate is false. */
864 eh_region_may_contain_throw (eh_region r)
866 return r && bitmap_bit_p (eh_region_may_contain_throw_map, r->index);
869 /* We want to transform
870 try { body; } catch { stuff; }
880 TP is a GIMPLE_TRY node. REGION is the region whose post_landing_pad
881 should be placed before the second operand, or NULL. OVER is
882 an existing label that should be put at the exit, or NULL. */
885 frob_into_branch_around (gimple tp, eh_region region, tree over)
888 gimple_seq cleanup, result;
889 location_t loc = gimple_location (tp);
891 cleanup = gimple_try_cleanup (tp);
892 result = gimple_try_eval (tp);
895 emit_post_landing_pad (&eh_seq, region);
897 if (gimple_seq_may_fallthru (cleanup))
900 over = create_artificial_label (loc);
901 x = gimple_build_goto (over);
902 gimple_seq_add_stmt (&cleanup, x);
904 gimple_seq_add_seq (&eh_seq, cleanup);
908 x = gimple_build_label (over);
909 gimple_seq_add_stmt (&result, x);
914 /* A subroutine of lower_try_finally. Duplicate the tree rooted at T.
915 Make sure to record all new labels found. */
918 lower_try_finally_dup_block (gimple_seq seq, struct leh_state *outer_state)
920 gimple region = NULL;
923 new_seq = copy_gimple_seq_and_replace_locals (seq);
926 region = outer_state->tf->try_finally_expr;
927 collect_finally_tree_1 (new_seq, region);
932 /* A subroutine of lower_try_finally. Create a fallthru label for
933 the given try_finally state. The only tricky bit here is that
934 we have to make sure to record the label in our outer context. */
937 lower_try_finally_fallthru_label (struct leh_tf_state *tf)
939 tree label = tf->fallthru_label;
944 label = create_artificial_label (gimple_location (tf->try_finally_expr));
945 tf->fallthru_label = label;
949 record_in_finally_tree (temp, tf->outer->tf->try_finally_expr);
955 /* A subroutine of lower_try_finally. If the eh_protect_cleanup_actions
956 langhook returns non-null, then the language requires that the exception
957 path out of a try_finally be treated specially. To wit: the code within
958 the finally block may not itself throw an exception. We have two choices
959 here. First we can duplicate the finally block and wrap it in a
960 must_not_throw region. Second, we can generate code like
965 if (fintmp == eh_edge)
966 protect_cleanup_actions;
969 where "fintmp" is the temporary used in the switch statement generation
970 alternative considered below. For the nonce, we always choose the first
973 THIS_STATE may be null if this is a try-cleanup, not a try-finally. */
976 honor_protect_cleanup_actions (struct leh_state *outer_state,
977 struct leh_state *this_state,
978 struct leh_tf_state *tf)
980 tree protect_cleanup_actions;
981 gimple_stmt_iterator gsi;
982 bool finally_may_fallthru;
986 /* First check for nothing to do. */
987 if (lang_hooks.eh_protect_cleanup_actions == NULL)
989 protect_cleanup_actions = lang_hooks.eh_protect_cleanup_actions ();
990 if (protect_cleanup_actions == NULL)
993 finally = gimple_try_cleanup (tf->top_p);
994 finally_may_fallthru = gimple_seq_may_fallthru (finally);
996 /* Duplicate the FINALLY block. Only need to do this for try-finally,
997 and not for cleanups. */
999 finally = lower_try_finally_dup_block (finally, outer_state);
1001 /* If this cleanup consists of a TRY_CATCH_EXPR with TRY_CATCH_IS_CLEANUP
1002 set, the handler of the TRY_CATCH_EXPR is another cleanup which ought
1003 to be in an enclosing scope, but needs to be implemented at this level
1004 to avoid a nesting violation (see wrap_temporary_cleanups in
1005 cp/decl.c). Since it's logically at an outer level, we should call
1006 terminate before we get to it, so strip it away before adding the
1007 MUST_NOT_THROW filter. */
1008 gsi = gsi_start (finally);
1010 if (gimple_code (x) == GIMPLE_TRY
1011 && gimple_try_kind (x) == GIMPLE_TRY_CATCH
1012 && gimple_try_catch_is_cleanup (x))
1014 gsi_insert_seq_before (&gsi, gimple_try_eval (x), GSI_SAME_STMT);
1015 gsi_remove (&gsi, false);
1018 /* Wrap the block with protect_cleanup_actions as the action. */
1019 x = gimple_build_eh_must_not_throw (protect_cleanup_actions);
1020 x = gimple_build_try (finally, gimple_seq_alloc_with_stmt (x),
1022 finally = lower_eh_must_not_throw (outer_state, x);
1024 /* Drop all of this into the exception sequence. */
1025 emit_post_landing_pad (&eh_seq, tf->region);
1026 gimple_seq_add_seq (&eh_seq, finally);
1027 if (finally_may_fallthru)
1028 emit_resx (&eh_seq, tf->region);
1030 /* Having now been handled, EH isn't to be considered with
1031 the rest of the outgoing edges. */
1032 tf->may_throw = false;
1035 /* A subroutine of lower_try_finally. We have determined that there is
1036 no fallthru edge out of the finally block. This means that there is
1037 no outgoing edge corresponding to any incoming edge. Restructure the
1038 try_finally node for this special case. */
1041 lower_try_finally_nofallthru (struct leh_state *state,
1042 struct leh_tf_state *tf)
1044 tree lab, return_val;
1047 struct goto_queue_node *q, *qe;
1049 lab = create_artificial_label (gimple_location (tf->try_finally_expr));
1051 /* We expect that tf->top_p is a GIMPLE_TRY. */
1052 finally = gimple_try_cleanup (tf->top_p);
1053 tf->top_p_seq = gimple_try_eval (tf->top_p);
1055 x = gimple_build_label (lab);
1056 gimple_seq_add_stmt (&tf->top_p_seq, x);
1060 qe = q + tf->goto_queue_active;
1063 do_return_redirection (q, lab, NULL, &return_val);
1065 do_goto_redirection (q, lab, NULL, tf);
1067 replace_goto_queue (tf);
1069 lower_eh_constructs_1 (state, finally);
1070 gimple_seq_add_seq (&tf->top_p_seq, finally);
1074 emit_post_landing_pad (&eh_seq, tf->region);
1076 x = gimple_build_goto (lab);
1077 gimple_seq_add_stmt (&eh_seq, x);
1081 /* A subroutine of lower_try_finally. We have determined that there is
1082 exactly one destination of the finally block. Restructure the
1083 try_finally node for this special case. */
1086 lower_try_finally_onedest (struct leh_state *state, struct leh_tf_state *tf)
1088 struct goto_queue_node *q, *qe;
1092 location_t loc = gimple_location (tf->try_finally_expr);
1094 finally = gimple_try_cleanup (tf->top_p);
1095 tf->top_p_seq = gimple_try_eval (tf->top_p);
1097 lower_eh_constructs_1 (state, finally);
1101 /* Only reachable via the exception edge. Add the given label to
1102 the head of the FINALLY block. Append a RESX at the end. */
1103 emit_post_landing_pad (&eh_seq, tf->region);
1104 gimple_seq_add_seq (&eh_seq, finally);
1105 emit_resx (&eh_seq, tf->region);
1109 if (tf->may_fallthru)
1111 /* Only reachable via the fallthru edge. Do nothing but let
1112 the two blocks run together; we'll fall out the bottom. */
1113 gimple_seq_add_seq (&tf->top_p_seq, finally);
1117 finally_label = create_artificial_label (loc);
1118 x = gimple_build_label (finally_label);
1119 gimple_seq_add_stmt (&tf->top_p_seq, x);
1121 gimple_seq_add_seq (&tf->top_p_seq, finally);
1124 qe = q + tf->goto_queue_active;
1128 /* Reachable by return expressions only. Redirect them. */
1129 tree return_val = NULL;
1131 do_return_redirection (q, finally_label, NULL, &return_val);
1132 replace_goto_queue (tf);
1136 /* Reachable by goto expressions only. Redirect them. */
1138 do_goto_redirection (q, finally_label, NULL, tf);
1139 replace_goto_queue (tf);
1141 if (VEC_index (tree, tf->dest_array, 0) == tf->fallthru_label)
1143 /* Reachable by goto to fallthru label only. Redirect it
1144 to the new label (already created, sadly), and do not
1145 emit the final branch out, or the fallthru label. */
1146 tf->fallthru_label = NULL;
1151 /* Place the original return/goto to the original destination
1152 immediately after the finally block. */
1153 x = tf->goto_queue[0].cont_stmt;
1154 gimple_seq_add_stmt (&tf->top_p_seq, x);
1155 maybe_record_in_goto_queue (state, x);
1158 /* A subroutine of lower_try_finally. There are multiple edges incoming
1159 and outgoing from the finally block. Implement this by duplicating the
1160 finally block for every destination. */
1163 lower_try_finally_copy (struct leh_state *state, struct leh_tf_state *tf)
1166 gimple_seq new_stmt;
1170 location_t tf_loc = gimple_location (tf->try_finally_expr);
1172 finally = gimple_try_cleanup (tf->top_p);
1173 tf->top_p_seq = gimple_try_eval (tf->top_p);
1176 if (tf->may_fallthru)
1178 seq = lower_try_finally_dup_block (finally, state);
1179 lower_eh_constructs_1 (state, seq);
1180 gimple_seq_add_seq (&new_stmt, seq);
1182 tmp = lower_try_finally_fallthru_label (tf);
1183 x = gimple_build_goto (tmp);
1184 gimple_seq_add_stmt (&new_stmt, x);
1189 seq = lower_try_finally_dup_block (finally, state);
1190 lower_eh_constructs_1 (state, seq);
1192 emit_post_landing_pad (&eh_seq, tf->region);
1193 gimple_seq_add_seq (&eh_seq, seq);
1194 emit_resx (&eh_seq, tf->region);
1199 struct goto_queue_node *q, *qe;
1200 tree return_val = NULL;
1201 int return_index, index;
1204 struct goto_queue_node *q;
1208 return_index = VEC_length (tree, tf->dest_array);
1209 labels = XCNEWVEC (struct labels_s, return_index + 1);
1212 qe = q + tf->goto_queue_active;
1215 index = q->index < 0 ? return_index : q->index;
1217 if (!labels[index].q)
1218 labels[index].q = q;
1221 for (index = 0; index < return_index + 1; index++)
1225 q = labels[index].q;
1229 lab = labels[index].label
1230 = create_artificial_label (tf_loc);
1232 if (index == return_index)
1233 do_return_redirection (q, lab, NULL, &return_val);
1235 do_goto_redirection (q, lab, NULL, tf);
1237 x = gimple_build_label (lab);
1238 gimple_seq_add_stmt (&new_stmt, x);
1240 seq = lower_try_finally_dup_block (finally, state);
1241 lower_eh_constructs_1 (state, seq);
1242 gimple_seq_add_seq (&new_stmt, seq);
1244 gimple_seq_add_stmt (&new_stmt, q->cont_stmt);
1245 maybe_record_in_goto_queue (state, q->cont_stmt);
1248 for (q = tf->goto_queue; q < qe; q++)
1252 index = q->index < 0 ? return_index : q->index;
1254 if (labels[index].q == q)
1257 lab = labels[index].label;
1259 if (index == return_index)
1260 do_return_redirection (q, lab, NULL, &return_val);
1262 do_goto_redirection (q, lab, NULL, tf);
1265 replace_goto_queue (tf);
1269 /* Need to link new stmts after running replace_goto_queue due
1270 to not wanting to process the same goto stmts twice. */
1271 gimple_seq_add_seq (&tf->top_p_seq, new_stmt);
1274 /* A subroutine of lower_try_finally. There are multiple edges incoming
1275 and outgoing from the finally block. Implement this by instrumenting
1276 each incoming edge and creating a switch statement at the end of the
1277 finally block that branches to the appropriate destination. */
1280 lower_try_finally_switch (struct leh_state *state, struct leh_tf_state *tf)
1282 struct goto_queue_node *q, *qe;
1283 tree return_val = NULL;
1284 tree finally_tmp, finally_label;
1285 int return_index, eh_index, fallthru_index;
1286 int nlabels, ndests, j, last_case_index;
1288 VEC (tree,heap) *case_label_vec;
1289 gimple_seq switch_body;
1294 struct pointer_map_t *cont_map = NULL;
1295 /* The location of the TRY_FINALLY stmt. */
1296 location_t tf_loc = gimple_location (tf->try_finally_expr);
1297 /* The location of the finally block. */
1298 location_t finally_loc;
1300 switch_body = gimple_seq_alloc ();
1302 /* Mash the TRY block to the head of the chain. */
1303 finally = gimple_try_cleanup (tf->top_p);
1304 tf->top_p_seq = gimple_try_eval (tf->top_p);
1306 /* The location of the finally is either the last stmt in the finally
1307 block or the location of the TRY_FINALLY itself. */
1308 finally_loc = gimple_seq_last_stmt (tf->top_p_seq) != NULL ?
1309 gimple_location (gimple_seq_last_stmt (tf->top_p_seq))
1312 /* Lower the finally block itself. */
1313 lower_eh_constructs_1 (state, finally);
1315 /* Prepare for switch statement generation. */
1316 nlabels = VEC_length (tree, tf->dest_array);
1317 return_index = nlabels;
1318 eh_index = return_index + tf->may_return;
1319 fallthru_index = eh_index + tf->may_throw;
1320 ndests = fallthru_index + tf->may_fallthru;
1322 finally_tmp = create_tmp_var (integer_type_node, "finally_tmp");
1323 finally_label = create_artificial_label (finally_loc);
1325 /* We use VEC_quick_push on case_label_vec throughout this function,
1326 since we know the size in advance and allocate precisely as muce
1328 case_label_vec = VEC_alloc (tree, heap, ndests);
1330 last_case_index = 0;
1332 /* Begin inserting code for getting to the finally block. Things
1333 are done in this order to correspond to the sequence the code is
1336 if (tf->may_fallthru)
1338 x = gimple_build_assign (finally_tmp,
1339 build_int_cst (integer_type_node,
1341 gimple_seq_add_stmt (&tf->top_p_seq, x);
1343 tmp = build_int_cst (integer_type_node, fallthru_index);
1344 last_case = build_case_label (tmp, NULL,
1345 create_artificial_label (tf_loc));
1346 VEC_quick_push (tree, case_label_vec, last_case);
1349 x = gimple_build_label (CASE_LABEL (last_case));
1350 gimple_seq_add_stmt (&switch_body, x);
1352 tmp = lower_try_finally_fallthru_label (tf);
1353 x = gimple_build_goto (tmp);
1354 gimple_seq_add_stmt (&switch_body, x);
1359 emit_post_landing_pad (&eh_seq, tf->region);
1361 x = gimple_build_assign (finally_tmp,
1362 build_int_cst (integer_type_node, eh_index));
1363 gimple_seq_add_stmt (&eh_seq, x);
1365 x = gimple_build_goto (finally_label);
1366 gimple_seq_add_stmt (&eh_seq, x);
1368 tmp = build_int_cst (integer_type_node, eh_index);
1369 last_case = build_case_label (tmp, NULL,
1370 create_artificial_label (tf_loc));
1371 VEC_quick_push (tree, case_label_vec, last_case);
1374 x = gimple_build_label (CASE_LABEL (last_case));
1375 gimple_seq_add_stmt (&eh_seq, x);
1376 emit_resx (&eh_seq, tf->region);
1379 x = gimple_build_label (finally_label);
1380 gimple_seq_add_stmt (&tf->top_p_seq, x);
1382 gimple_seq_add_seq (&tf->top_p_seq, finally);
1384 /* Redirect each incoming goto edge. */
1386 qe = q + tf->goto_queue_active;
1387 j = last_case_index + tf->may_return;
1388 /* Prepare the assignments to finally_tmp that are executed upon the
1389 entrance through a particular edge. */
1394 unsigned int case_index;
1396 mod = gimple_seq_alloc ();
1400 x = gimple_build_assign (finally_tmp,
1401 build_int_cst (integer_type_node,
1403 gimple_seq_add_stmt (&mod, x);
1404 do_return_redirection (q, finally_label, mod, &return_val);
1405 switch_id = return_index;
1409 x = gimple_build_assign (finally_tmp,
1410 build_int_cst (integer_type_node, q->index));
1411 gimple_seq_add_stmt (&mod, x);
1412 do_goto_redirection (q, finally_label, mod, tf);
1413 switch_id = q->index;
1416 case_index = j + q->index;
1417 if (VEC_length (tree, case_label_vec) <= case_index
1418 || !VEC_index (tree, case_label_vec, case_index))
1422 tmp = build_int_cst (integer_type_node, switch_id);
1423 case_lab = build_case_label (tmp, NULL,
1424 create_artificial_label (tf_loc));
1425 /* We store the cont_stmt in the pointer map, so that we can recover
1426 it in the loop below. */
1428 cont_map = pointer_map_create ();
1429 slot = pointer_map_insert (cont_map, case_lab);
1430 *slot = q->cont_stmt;
1431 VEC_quick_push (tree, case_label_vec, case_lab);
1434 for (j = last_case_index; j < last_case_index + nlabels; j++)
1439 last_case = VEC_index (tree, case_label_vec, j);
1441 gcc_assert (last_case);
1442 gcc_assert (cont_map);
1444 slot = pointer_map_contains (cont_map, last_case);
1446 cont_stmt = *(gimple *) slot;
1448 x = gimple_build_label (CASE_LABEL (last_case));
1449 gimple_seq_add_stmt (&switch_body, x);
1450 gimple_seq_add_stmt (&switch_body, cont_stmt);
1451 maybe_record_in_goto_queue (state, cont_stmt);
1454 pointer_map_destroy (cont_map);
1456 replace_goto_queue (tf);
1458 /* Make sure that the last case is the default label, as one is required.
1459 Then sort the labels, which is also required in GIMPLE. */
1460 CASE_LOW (last_case) = NULL;
1461 sort_case_labels (case_label_vec);
1463 /* Build the switch statement, setting last_case to be the default
1465 switch_stmt = gimple_build_switch_vec (finally_tmp, last_case,
1467 gimple_set_location (switch_stmt, finally_loc);
1469 /* Need to link SWITCH_STMT after running replace_goto_queue
1470 due to not wanting to process the same goto stmts twice. */
1471 gimple_seq_add_stmt (&tf->top_p_seq, switch_stmt);
1472 gimple_seq_add_seq (&tf->top_p_seq, switch_body);
1475 /* Decide whether or not we are going to duplicate the finally block.
1476 There are several considerations.
1478 First, if this is Java, then the finally block contains code
1479 written by the user. It has line numbers associated with it,
1480 so duplicating the block means it's difficult to set a breakpoint.
1481 Since controlling code generation via -g is verboten, we simply
1482 never duplicate code without optimization.
1484 Second, we'd like to prevent egregious code growth. One way to
1485 do this is to estimate the size of the finally block, multiply
1486 that by the number of copies we'd need to make, and compare against
1487 the estimate of the size of the switch machinery we'd have to add. */
1490 decide_copy_try_finally (int ndests, gimple_seq finally)
1492 int f_estimate, sw_estimate;
1497 /* Finally estimate N times, plus N gotos. */
1498 f_estimate = count_insns_seq (finally, &eni_size_weights);
1499 f_estimate = (f_estimate + 1) * ndests;
1501 /* Switch statement (cost 10), N variable assignments, N gotos. */
1502 sw_estimate = 10 + 2 * ndests;
1504 /* Optimize for size clearly wants our best guess. */
1505 if (optimize_function_for_size_p (cfun))
1506 return f_estimate < sw_estimate;
1508 /* ??? These numbers are completely made up so far. */
1510 return f_estimate < 100 || f_estimate < sw_estimate * 2;
1512 return f_estimate < 40 || f_estimate * 2 < sw_estimate * 3;
1515 /* REG is the enclosing region for a possible cleanup region, or the region
1516 itself. Returns TRUE if such a region would be unreachable.
1518 Cleanup regions within a must-not-throw region aren't actually reachable
1519 even if there are throwing stmts within them, because the personality
1520 routine will call terminate before unwinding. */
1523 cleanup_is_dead_in (eh_region reg)
1525 while (reg && reg->type == ERT_CLEANUP)
1527 return (reg && reg->type == ERT_MUST_NOT_THROW);
1530 /* A subroutine of lower_eh_constructs_1. Lower a GIMPLE_TRY_FINALLY nodes
1531 to a sequence of labels and blocks, plus the exception region trees
1532 that record all the magic. This is complicated by the need to
1533 arrange for the FINALLY block to be executed on all exits. */
1536 lower_try_finally (struct leh_state *state, gimple tp)
1538 struct leh_tf_state this_tf;
1539 struct leh_state this_state;
1541 gimple_seq old_eh_seq;
1543 /* Process the try block. */
1545 memset (&this_tf, 0, sizeof (this_tf));
1546 this_tf.try_finally_expr = tp;
1548 this_tf.outer = state;
1549 if (using_eh_for_cleanups_p && !cleanup_is_dead_in (state->cur_region))
1551 this_tf.region = gen_eh_region_cleanup (state->cur_region);
1552 this_state.cur_region = this_tf.region;
1556 this_tf.region = NULL;
1557 this_state.cur_region = state->cur_region;
1560 this_state.ehp_region = state->ehp_region;
1561 this_state.tf = &this_tf;
1563 old_eh_seq = eh_seq;
1566 lower_eh_constructs_1 (&this_state, gimple_try_eval(tp));
1568 /* Determine if the try block is escaped through the bottom. */
1569 this_tf.may_fallthru = gimple_seq_may_fallthru (gimple_try_eval (tp));
1571 /* Determine if any exceptions are possible within the try block. */
1573 this_tf.may_throw = eh_region_may_contain_throw (this_tf.region);
1574 if (this_tf.may_throw)
1575 honor_protect_cleanup_actions (state, &this_state, &this_tf);
1577 /* Determine how many edges (still) reach the finally block. Or rather,
1578 how many destinations are reached by the finally block. Use this to
1579 determine how we process the finally block itself. */
1581 ndests = VEC_length (tree, this_tf.dest_array);
1582 ndests += this_tf.may_fallthru;
1583 ndests += this_tf.may_return;
1584 ndests += this_tf.may_throw;
1586 /* If the FINALLY block is not reachable, dike it out. */
1589 gimple_seq_add_seq (&this_tf.top_p_seq, gimple_try_eval (tp));
1590 gimple_try_set_cleanup (tp, NULL);
1592 /* If the finally block doesn't fall through, then any destination
1593 we might try to impose there isn't reached either. There may be
1594 some minor amount of cleanup and redirection still needed. */
1595 else if (!gimple_seq_may_fallthru (gimple_try_cleanup (tp)))
1596 lower_try_finally_nofallthru (state, &this_tf);
1598 /* We can easily special-case redirection to a single destination. */
1599 else if (ndests == 1)
1600 lower_try_finally_onedest (state, &this_tf);
1601 else if (decide_copy_try_finally (ndests, gimple_try_cleanup (tp)))
1602 lower_try_finally_copy (state, &this_tf);
1604 lower_try_finally_switch (state, &this_tf);
1606 /* If someone requested we add a label at the end of the transformed
1608 if (this_tf.fallthru_label)
1610 /* This must be reached only if ndests == 0. */
1611 gimple x = gimple_build_label (this_tf.fallthru_label);
1612 gimple_seq_add_stmt (&this_tf.top_p_seq, x);
1615 VEC_free (tree, heap, this_tf.dest_array);
1616 free (this_tf.goto_queue);
1617 if (this_tf.goto_queue_map)
1618 pointer_map_destroy (this_tf.goto_queue_map);
1620 /* If there was an old (aka outer) eh_seq, append the current eh_seq.
1621 If there was no old eh_seq, then the append is trivially already done. */
1625 eh_seq = old_eh_seq;
1628 gimple_seq new_eh_seq = eh_seq;
1629 eh_seq = old_eh_seq;
1630 gimple_seq_add_seq(&eh_seq, new_eh_seq);
1634 return this_tf.top_p_seq;
1637 /* A subroutine of lower_eh_constructs_1. Lower a GIMPLE_TRY_CATCH with a
1638 list of GIMPLE_CATCH to a sequence of labels and blocks, plus the
1639 exception region trees that records all the magic. */
1642 lower_catch (struct leh_state *state, gimple tp)
1644 eh_region try_region = NULL;
1645 struct leh_state this_state = *state;
1646 gimple_stmt_iterator gsi;
1650 location_t try_catch_loc = gimple_location (tp);
1652 if (flag_exceptions)
1654 try_region = gen_eh_region_try (state->cur_region);
1655 this_state.cur_region = try_region;
1658 lower_eh_constructs_1 (&this_state, gimple_try_eval (tp));
1660 if (!eh_region_may_contain_throw (try_region))
1661 return gimple_try_eval (tp);
1664 emit_eh_dispatch (&new_seq, try_region);
1665 emit_resx (&new_seq, try_region);
1667 this_state.cur_region = state->cur_region;
1668 this_state.ehp_region = try_region;
1671 for (gsi = gsi_start (gimple_try_cleanup (tp));
1679 gcatch = gsi_stmt (gsi);
1680 c = gen_eh_region_catch (try_region, gimple_catch_types (gcatch));
1682 handler = gimple_catch_handler (gcatch);
1683 lower_eh_constructs_1 (&this_state, handler);
1685 c->label = create_artificial_label (UNKNOWN_LOCATION);
1686 x = gimple_build_label (c->label);
1687 gimple_seq_add_stmt (&new_seq, x);
1689 gimple_seq_add_seq (&new_seq, handler);
1691 if (gimple_seq_may_fallthru (new_seq))
1694 out_label = create_artificial_label (try_catch_loc);
1696 x = gimple_build_goto (out_label);
1697 gimple_seq_add_stmt (&new_seq, x);
1703 gimple_try_set_cleanup (tp, new_seq);
1705 return frob_into_branch_around (tp, try_region, out_label);
1708 /* A subroutine of lower_eh_constructs_1. Lower a GIMPLE_TRY with a
1709 GIMPLE_EH_FILTER to a sequence of labels and blocks, plus the exception
1710 region trees that record all the magic. */
1713 lower_eh_filter (struct leh_state *state, gimple tp)
1715 struct leh_state this_state = *state;
1716 eh_region this_region = NULL;
1720 inner = gimple_seq_first_stmt (gimple_try_cleanup (tp));
1722 if (flag_exceptions)
1724 this_region = gen_eh_region_allowed (state->cur_region,
1725 gimple_eh_filter_types (inner));
1726 this_state.cur_region = this_region;
1729 lower_eh_constructs_1 (&this_state, gimple_try_eval (tp));
1731 if (!eh_region_may_contain_throw (this_region))
1732 return gimple_try_eval (tp);
1735 this_state.cur_region = state->cur_region;
1736 this_state.ehp_region = this_region;
1738 emit_eh_dispatch (&new_seq, this_region);
1739 emit_resx (&new_seq, this_region);
1741 this_region->u.allowed.label = create_artificial_label (UNKNOWN_LOCATION);
1742 x = gimple_build_label (this_region->u.allowed.label);
1743 gimple_seq_add_stmt (&new_seq, x);
1745 lower_eh_constructs_1 (&this_state, gimple_eh_filter_failure (inner));
1746 gimple_seq_add_seq (&new_seq, gimple_eh_filter_failure (inner));
1748 gimple_try_set_cleanup (tp, new_seq);
1750 return frob_into_branch_around (tp, this_region, NULL);
1753 /* A subroutine of lower_eh_constructs_1. Lower a GIMPLE_TRY with
1754 an GIMPLE_EH_MUST_NOT_THROW to a sequence of labels and blocks,
1755 plus the exception region trees that record all the magic. */
1758 lower_eh_must_not_throw (struct leh_state *state, gimple tp)
1760 struct leh_state this_state = *state;
1762 if (flag_exceptions)
1764 gimple inner = gimple_seq_first_stmt (gimple_try_cleanup (tp));
1765 eh_region this_region;
1767 this_region = gen_eh_region_must_not_throw (state->cur_region);
1768 this_region->u.must_not_throw.failure_decl
1769 = gimple_eh_must_not_throw_fndecl (inner);
1770 this_region->u.must_not_throw.failure_loc = gimple_location (tp);
1772 /* In order to get mangling applied to this decl, we must mark it
1773 used now. Otherwise, pass_ipa_free_lang_data won't think it
1775 TREE_USED (this_region->u.must_not_throw.failure_decl) = 1;
1777 this_state.cur_region = this_region;
1780 lower_eh_constructs_1 (&this_state, gimple_try_eval (tp));
1782 return gimple_try_eval (tp);
1785 /* Implement a cleanup expression. This is similar to try-finally,
1786 except that we only execute the cleanup block for exception edges. */
1789 lower_cleanup (struct leh_state *state, gimple tp)
1791 struct leh_state this_state = *state;
1792 eh_region this_region = NULL;
1793 struct leh_tf_state fake_tf;
1795 bool cleanup_dead = cleanup_is_dead_in (state->cur_region);
1797 if (flag_exceptions && !cleanup_dead)
1799 this_region = gen_eh_region_cleanup (state->cur_region);
1800 this_state.cur_region = this_region;
1803 lower_eh_constructs_1 (&this_state, gimple_try_eval (tp));
1805 if (cleanup_dead || !eh_region_may_contain_throw (this_region))
1806 return gimple_try_eval (tp);
1808 /* Build enough of a try-finally state so that we can reuse
1809 honor_protect_cleanup_actions. */
1810 memset (&fake_tf, 0, sizeof (fake_tf));
1811 fake_tf.top_p = fake_tf.try_finally_expr = tp;
1812 fake_tf.outer = state;
1813 fake_tf.region = this_region;
1814 fake_tf.may_fallthru = gimple_seq_may_fallthru (gimple_try_eval (tp));
1815 fake_tf.may_throw = true;
1817 honor_protect_cleanup_actions (state, NULL, &fake_tf);
1819 if (fake_tf.may_throw)
1821 /* In this case honor_protect_cleanup_actions had nothing to do,
1822 and we should process this normally. */
1823 lower_eh_constructs_1 (state, gimple_try_cleanup (tp));
1824 result = frob_into_branch_around (tp, this_region,
1825 fake_tf.fallthru_label);
1829 /* In this case honor_protect_cleanup_actions did nearly all of
1830 the work. All we have left is to append the fallthru_label. */
1832 result = gimple_try_eval (tp);
1833 if (fake_tf.fallthru_label)
1835 gimple x = gimple_build_label (fake_tf.fallthru_label);
1836 gimple_seq_add_stmt (&result, x);
1842 /* Main loop for lowering eh constructs. Also moves gsi to the next
1846 lower_eh_constructs_2 (struct leh_state *state, gimple_stmt_iterator *gsi)
1850 gimple stmt = gsi_stmt (*gsi);
1852 switch (gimple_code (stmt))
1856 tree fndecl = gimple_call_fndecl (stmt);
1859 if (fndecl && DECL_BUILT_IN_CLASS (fndecl) == BUILT_IN_NORMAL)
1860 switch (DECL_FUNCTION_CODE (fndecl))
1862 case BUILT_IN_EH_POINTER:
1863 /* The front end may have generated a call to
1864 __builtin_eh_pointer (0) within a catch region. Replace
1865 this zero argument with the current catch region number. */
1866 if (state->ehp_region)
1868 tree nr = build_int_cst (integer_type_node,
1869 state->ehp_region->index);
1870 gimple_call_set_arg (stmt, 0, nr);
1874 /* The user has dome something silly. Remove it. */
1875 rhs = null_pointer_node;
1880 case BUILT_IN_EH_FILTER:
1881 /* ??? This should never appear, but since it's a builtin it
1882 is accessible to abuse by users. Just remove it and
1883 replace the use with the arbitrary value zero. */
1884 rhs = build_int_cst (TREE_TYPE (TREE_TYPE (fndecl)), 0);
1886 lhs = gimple_call_lhs (stmt);
1887 x = gimple_build_assign (lhs, rhs);
1888 gsi_insert_before (gsi, x, GSI_SAME_STMT);
1891 case BUILT_IN_EH_COPY_VALUES:
1892 /* Likewise this should not appear. Remove it. */
1893 gsi_remove (gsi, true);
1903 /* If the stmt can throw use a new temporary for the assignment
1904 to a LHS. This makes sure the old value of the LHS is
1905 available on the EH edge. Only do so for statements that
1906 potentially fall thru (no noreturn calls e.g.), otherwise
1907 this new assignment might create fake fallthru regions. */
1908 if (stmt_could_throw_p (stmt)
1909 && gimple_has_lhs (stmt)
1910 && gimple_stmt_may_fallthru (stmt)
1911 && !tree_could_throw_p (gimple_get_lhs (stmt))
1912 && is_gimple_reg_type (TREE_TYPE (gimple_get_lhs (stmt))))
1914 tree lhs = gimple_get_lhs (stmt);
1915 tree tmp = create_tmp_var (TREE_TYPE (lhs), NULL);
1916 gimple s = gimple_build_assign (lhs, tmp);
1917 gimple_set_location (s, gimple_location (stmt));
1918 gimple_set_block (s, gimple_block (stmt));
1919 gimple_set_lhs (stmt, tmp);
1920 if (TREE_CODE (TREE_TYPE (tmp)) == COMPLEX_TYPE
1921 || TREE_CODE (TREE_TYPE (tmp)) == VECTOR_TYPE)
1922 DECL_GIMPLE_REG_P (tmp) = 1;
1923 gsi_insert_after (gsi, s, GSI_SAME_STMT);
1925 /* Look for things that can throw exceptions, and record them. */
1926 if (state->cur_region && stmt_could_throw_p (stmt))
1928 record_stmt_eh_region (state->cur_region, stmt);
1929 note_eh_region_may_contain_throw (state->cur_region);
1936 maybe_record_in_goto_queue (state, stmt);
1940 verify_norecord_switch_expr (state, stmt);
1944 if (gimple_try_kind (stmt) == GIMPLE_TRY_FINALLY)
1945 replace = lower_try_finally (state, stmt);
1948 x = gimple_seq_first_stmt (gimple_try_cleanup (stmt));
1951 replace = gimple_try_eval (stmt);
1952 lower_eh_constructs_1 (state, replace);
1955 switch (gimple_code (x))
1958 replace = lower_catch (state, stmt);
1960 case GIMPLE_EH_FILTER:
1961 replace = lower_eh_filter (state, stmt);
1963 case GIMPLE_EH_MUST_NOT_THROW:
1964 replace = lower_eh_must_not_throw (state, stmt);
1967 replace = lower_cleanup (state, stmt);
1972 /* Remove the old stmt and insert the transformed sequence
1974 gsi_insert_seq_before (gsi, replace, GSI_SAME_STMT);
1975 gsi_remove (gsi, true);
1977 /* Return since we don't want gsi_next () */
1981 /* A type, a decl, or some kind of statement that we're not
1982 interested in. Don't walk them. */
1989 /* A helper to unwrap a gimple_seq and feed stmts to lower_eh_constructs_2. */
1992 lower_eh_constructs_1 (struct leh_state *state, gimple_seq seq)
1994 gimple_stmt_iterator gsi;
1995 for (gsi = gsi_start (seq); !gsi_end_p (gsi);)
1996 lower_eh_constructs_2 (state, &gsi);
2000 lower_eh_constructs (void)
2002 struct leh_state null_state;
2005 bodyp = gimple_body (current_function_decl);
2009 finally_tree = htab_create (31, struct_ptr_hash, struct_ptr_eq, free);
2010 eh_region_may_contain_throw_map = BITMAP_ALLOC (NULL);
2011 memset (&null_state, 0, sizeof (null_state));
2013 collect_finally_tree_1 (bodyp, NULL);
2014 lower_eh_constructs_1 (&null_state, bodyp);
2016 /* We assume there's a return statement, or something, at the end of
2017 the function, and thus ploping the EH sequence afterward won't
2019 gcc_assert (!gimple_seq_may_fallthru (bodyp));
2020 gimple_seq_add_seq (&bodyp, eh_seq);
2022 /* We assume that since BODYP already existed, adding EH_SEQ to it
2023 didn't change its value, and we don't have to re-set the function. */
2024 gcc_assert (bodyp == gimple_body (current_function_decl));
2026 htab_delete (finally_tree);
2027 BITMAP_FREE (eh_region_may_contain_throw_map);
2030 /* If this function needs a language specific EH personality routine
2031 and the frontend didn't already set one do so now. */
2032 if (function_needs_eh_personality (cfun) == eh_personality_lang
2033 && !DECL_FUNCTION_PERSONALITY (current_function_decl))
2034 DECL_FUNCTION_PERSONALITY (current_function_decl)
2035 = lang_hooks.eh_personality ();
2040 struct gimple_opt_pass pass_lower_eh =
2046 lower_eh_constructs, /* execute */
2049 0, /* static_pass_number */
2050 TV_TREE_EH, /* tv_id */
2051 PROP_gimple_lcf, /* properties_required */
2052 PROP_gimple_leh, /* properties_provided */
2053 0, /* properties_destroyed */
2054 0, /* todo_flags_start */
2055 TODO_dump_func /* todo_flags_finish */
2059 /* Create the multiple edges from an EH_DISPATCH statement to all of
2060 the possible handlers for its EH region. Return true if there's
2061 no fallthru edge; false if there is. */
2064 make_eh_dispatch_edges (gimple stmt)
2068 basic_block src, dst;
2070 r = get_eh_region_from_number (gimple_eh_dispatch_region (stmt));
2071 src = gimple_bb (stmt);
2076 for (c = r->u.eh_try.first_catch; c ; c = c->next_catch)
2078 dst = label_to_block (c->label);
2079 make_edge (src, dst, 0);
2081 /* A catch-all handler doesn't have a fallthru. */
2082 if (c->type_list == NULL)
2087 case ERT_ALLOWED_EXCEPTIONS:
2088 dst = label_to_block (r->u.allowed.label);
2089 make_edge (src, dst, 0);
2099 /* Create the single EH edge from STMT to its nearest landing pad,
2100 if there is such a landing pad within the current function. */
2103 make_eh_edges (gimple stmt)
2105 basic_block src, dst;
2109 lp_nr = lookup_stmt_eh_lp (stmt);
2113 lp = get_eh_landing_pad_from_number (lp_nr);
2114 gcc_assert (lp != NULL);
2116 src = gimple_bb (stmt);
2117 dst = label_to_block (lp->post_landing_pad);
2118 make_edge (src, dst, EDGE_EH);
2121 /* Do the work in redirecting EDGE_IN to NEW_BB within the EH region tree;
2122 do not actually perform the final edge redirection.
2124 CHANGE_REGION is true when we're being called from cleanup_empty_eh and
2125 we intend to change the destination EH region as well; this means
2126 EH_LANDING_PAD_NR must already be set on the destination block label.
2127 If false, we're being called from generic cfg manipulation code and we
2128 should preserve our place within the region tree. */
2131 redirect_eh_edge_1 (edge edge_in, basic_block new_bb, bool change_region)
2133 eh_landing_pad old_lp, new_lp;
2136 int old_lp_nr, new_lp_nr;
2137 tree old_label, new_label;
2141 old_bb = edge_in->dest;
2142 old_label = gimple_block_label (old_bb);
2143 old_lp_nr = EH_LANDING_PAD_NR (old_label);
2144 gcc_assert (old_lp_nr > 0);
2145 old_lp = get_eh_landing_pad_from_number (old_lp_nr);
2147 throw_stmt = last_stmt (edge_in->src);
2148 gcc_assert (lookup_stmt_eh_lp (throw_stmt) == old_lp_nr);
2150 new_label = gimple_block_label (new_bb);
2152 /* Look for an existing region that might be using NEW_BB already. */
2153 new_lp_nr = EH_LANDING_PAD_NR (new_label);
2156 new_lp = get_eh_landing_pad_from_number (new_lp_nr);
2157 gcc_assert (new_lp);
2159 /* Unless CHANGE_REGION is true, the new and old landing pad
2160 had better be associated with the same EH region. */
2161 gcc_assert (change_region || new_lp->region == old_lp->region);
2166 gcc_assert (!change_region);
2169 /* Notice when we redirect the last EH edge away from OLD_BB. */
2170 FOR_EACH_EDGE (e, ei, old_bb->preds)
2171 if (e != edge_in && (e->flags & EDGE_EH))
2176 /* NEW_LP already exists. If there are still edges into OLD_LP,
2177 there's nothing to do with the EH tree. If there are no more
2178 edges into OLD_LP, then we want to remove OLD_LP as it is unused.
2179 If CHANGE_REGION is true, then our caller is expecting to remove
2181 if (e == NULL && !change_region)
2182 remove_eh_landing_pad (old_lp);
2186 /* No correct landing pad exists. If there are no more edges
2187 into OLD_LP, then we can simply re-use the existing landing pad.
2188 Otherwise, we have to create a new landing pad. */
2191 EH_LANDING_PAD_NR (old_lp->post_landing_pad) = 0;
2195 new_lp = gen_eh_landing_pad (old_lp->region);
2196 new_lp->post_landing_pad = new_label;
2197 EH_LANDING_PAD_NR (new_label) = new_lp->index;
2200 /* Maybe move the throwing statement to the new region. */
2201 if (old_lp != new_lp)
2203 remove_stmt_from_eh_lp (throw_stmt);
2204 add_stmt_to_eh_lp (throw_stmt, new_lp->index);
2208 /* Redirect EH edge E to NEW_BB. */
2211 redirect_eh_edge (edge edge_in, basic_block new_bb)
2213 redirect_eh_edge_1 (edge_in, new_bb, false);
2214 return ssa_redirect_edge (edge_in, new_bb);
2217 /* This is a subroutine of gimple_redirect_edge_and_branch. Update the
2218 labels for redirecting a non-fallthru EH_DISPATCH edge E to NEW_BB.
2219 The actual edge update will happen in the caller. */
2222 redirect_eh_dispatch_edge (gimple stmt, edge e, basic_block new_bb)
2224 tree new_lab = gimple_block_label (new_bb);
2225 bool any_changed = false;
2230 r = get_eh_region_from_number (gimple_eh_dispatch_region (stmt));
2234 for (c = r->u.eh_try.first_catch; c ; c = c->next_catch)
2236 old_bb = label_to_block (c->label);
2237 if (old_bb == e->dest)
2245 case ERT_ALLOWED_EXCEPTIONS:
2246 old_bb = label_to_block (r->u.allowed.label);
2247 gcc_assert (old_bb == e->dest);
2248 r->u.allowed.label = new_lab;
2256 gcc_assert (any_changed);
2259 /* Helper function for operation_could_trap_p and stmt_could_throw_p. */
2262 operation_could_trap_helper_p (enum tree_code op,
2273 case TRUNC_DIV_EXPR:
2275 case FLOOR_DIV_EXPR:
2276 case ROUND_DIV_EXPR:
2277 case EXACT_DIV_EXPR:
2279 case FLOOR_MOD_EXPR:
2280 case ROUND_MOD_EXPR:
2281 case TRUNC_MOD_EXPR:
2283 if (honor_snans || honor_trapv)
2286 return flag_trapping_math;
2287 if (!TREE_CONSTANT (divisor) || integer_zerop (divisor))
2296 /* Some floating point comparisons may trap. */
2301 case UNORDERED_EXPR:
2311 case FIX_TRUNC_EXPR:
2312 /* Conversion of floating point might trap. */
2318 /* These operations don't trap with floating point. */
2326 /* Any floating arithmetic may trap. */
2327 if (fp_operation && flag_trapping_math)
2335 /* Constructing an object cannot trap. */
2339 /* Any floating arithmetic may trap. */
2340 if (fp_operation && flag_trapping_math)
2348 /* Return true if operation OP may trap. FP_OPERATION is true if OP is applied
2349 on floating-point values. HONOR_TRAPV is true if OP is applied on integer
2350 type operands that may trap. If OP is a division operator, DIVISOR contains
2351 the value of the divisor. */
2354 operation_could_trap_p (enum tree_code op, bool fp_operation, bool honor_trapv,
2357 bool honor_nans = (fp_operation && flag_trapping_math
2358 && !flag_finite_math_only);
2359 bool honor_snans = fp_operation && flag_signaling_nans != 0;
2362 if (TREE_CODE_CLASS (op) != tcc_comparison
2363 && TREE_CODE_CLASS (op) != tcc_unary
2364 && TREE_CODE_CLASS (op) != tcc_binary)
2367 return operation_could_trap_helper_p (op, fp_operation, honor_trapv,
2368 honor_nans, honor_snans, divisor,
2372 /* Return true if EXPR can trap, as in dereferencing an invalid pointer
2373 location or floating point arithmetic. C.f. the rtl version, may_trap_p.
2374 This routine expects only GIMPLE lhs or rhs input. */
2377 tree_could_trap_p (tree expr)
2379 enum tree_code code;
2380 bool fp_operation = false;
2381 bool honor_trapv = false;
2382 tree t, base, div = NULL_TREE;
2387 code = TREE_CODE (expr);
2388 t = TREE_TYPE (expr);
2392 if (COMPARISON_CLASS_P (expr))
2393 fp_operation = FLOAT_TYPE_P (TREE_TYPE (TREE_OPERAND (expr, 0)));
2395 fp_operation = FLOAT_TYPE_P (t);
2396 honor_trapv = INTEGRAL_TYPE_P (t) && TYPE_OVERFLOW_TRAPS (t);
2399 if (TREE_CODE_CLASS (code) == tcc_binary)
2400 div = TREE_OPERAND (expr, 1);
2401 if (operation_could_trap_p (code, fp_operation, honor_trapv, div))
2407 case TARGET_MEM_REF:
2408 if (TREE_CODE (TMR_BASE (expr)) == ADDR_EXPR
2409 && !TMR_INDEX (expr) && !TMR_INDEX2 (expr))
2411 return !TREE_THIS_NOTRAP (expr);
2417 case VIEW_CONVERT_EXPR:
2418 case WITH_SIZE_EXPR:
2419 expr = TREE_OPERAND (expr, 0);
2420 code = TREE_CODE (expr);
2423 case ARRAY_RANGE_REF:
2424 base = TREE_OPERAND (expr, 0);
2425 if (tree_could_trap_p (base))
2427 if (TREE_THIS_NOTRAP (expr))
2429 return !range_in_array_bounds_p (expr);
2432 base = TREE_OPERAND (expr, 0);
2433 if (tree_could_trap_p (base))
2435 if (TREE_THIS_NOTRAP (expr))
2437 return !in_array_bounds_p (expr);
2440 if (TREE_CODE (TREE_OPERAND (expr, 0)) == ADDR_EXPR)
2444 return !TREE_THIS_NOTRAP (expr);
2447 return TREE_THIS_VOLATILE (expr);
2450 t = get_callee_fndecl (expr);
2451 /* Assume that calls to weak functions may trap. */
2452 if (!t || !DECL_P (t) || DECL_WEAK (t))
2462 /* Helper for stmt_could_throw_p. Return true if STMT (assumed to be a
2463 an assignment or a conditional) may throw. */
2466 stmt_could_throw_1_p (gimple stmt)
2468 enum tree_code code = gimple_expr_code (stmt);
2469 bool honor_nans = false;
2470 bool honor_snans = false;
2471 bool fp_operation = false;
2472 bool honor_trapv = false;
2477 if (TREE_CODE_CLASS (code) == tcc_comparison
2478 || TREE_CODE_CLASS (code) == tcc_unary
2479 || TREE_CODE_CLASS (code) == tcc_binary)
2481 t = gimple_expr_type (stmt);
2482 fp_operation = FLOAT_TYPE_P (t);
2485 honor_nans = flag_trapping_math && !flag_finite_math_only;
2486 honor_snans = flag_signaling_nans != 0;
2488 else if (INTEGRAL_TYPE_P (t) && TYPE_OVERFLOW_TRAPS (t))
2492 /* Check if the main expression may trap. */
2493 t = is_gimple_assign (stmt) ? gimple_assign_rhs2 (stmt) : NULL;
2494 ret = operation_could_trap_helper_p (code, fp_operation, honor_trapv,
2495 honor_nans, honor_snans, t,
2500 /* If the expression does not trap, see if any of the individual operands may
2502 for (i = 0; i < gimple_num_ops (stmt); i++)
2503 if (tree_could_trap_p (gimple_op (stmt, i)))
2510 /* Return true if statement STMT could throw an exception. */
2513 stmt_could_throw_p (gimple stmt)
2515 if (!flag_exceptions)
2518 /* The only statements that can throw an exception are assignments,
2519 conditionals, calls, resx, and asms. */
2520 switch (gimple_code (stmt))
2526 return !gimple_call_nothrow_p (stmt);
2530 if (!cfun->can_throw_non_call_exceptions)
2532 return stmt_could_throw_1_p (stmt);
2535 if (!cfun->can_throw_non_call_exceptions)
2537 return gimple_asm_volatile_p (stmt);
2545 /* Return true if expression T could throw an exception. */
2548 tree_could_throw_p (tree t)
2550 if (!flag_exceptions)
2552 if (TREE_CODE (t) == MODIFY_EXPR)
2554 if (cfun->can_throw_non_call_exceptions
2555 && tree_could_trap_p (TREE_OPERAND (t, 0)))
2557 t = TREE_OPERAND (t, 1);
2560 if (TREE_CODE (t) == WITH_SIZE_EXPR)
2561 t = TREE_OPERAND (t, 0);
2562 if (TREE_CODE (t) == CALL_EXPR)
2563 return (call_expr_flags (t) & ECF_NOTHROW) == 0;
2564 if (cfun->can_throw_non_call_exceptions)
2565 return tree_could_trap_p (t);
2569 /* Return true if STMT can throw an exception that is not caught within
2570 the current function (CFUN). */
2573 stmt_can_throw_external (gimple stmt)
2577 if (!stmt_could_throw_p (stmt))
2580 lp_nr = lookup_stmt_eh_lp (stmt);
2584 /* Return true if STMT can throw an exception that is caught within
2585 the current function (CFUN). */
2588 stmt_can_throw_internal (gimple stmt)
2592 if (!stmt_could_throw_p (stmt))
2595 lp_nr = lookup_stmt_eh_lp (stmt);
2599 /* Given a statement STMT in IFUN, if STMT can no longer throw, then
2600 remove any entry it might have from the EH table. Return true if
2601 any change was made. */
2604 maybe_clean_eh_stmt_fn (struct function *ifun, gimple stmt)
2606 if (stmt_could_throw_p (stmt))
2608 return remove_stmt_from_eh_lp_fn (ifun, stmt);
2611 /* Likewise, but always use the current function. */
2614 maybe_clean_eh_stmt (gimple stmt)
2616 return maybe_clean_eh_stmt_fn (cfun, stmt);
2619 /* Given a statement OLD_STMT and a new statement NEW_STMT that has replaced
2620 OLD_STMT in the function, remove OLD_STMT from the EH table and put NEW_STMT
2621 in the table if it should be in there. Return TRUE if a replacement was
2622 done that my require an EH edge purge. */
2625 maybe_clean_or_replace_eh_stmt (gimple old_stmt, gimple new_stmt)
2627 int lp_nr = lookup_stmt_eh_lp (old_stmt);
2631 bool new_stmt_could_throw = stmt_could_throw_p (new_stmt);
2633 if (new_stmt == old_stmt && new_stmt_could_throw)
2636 remove_stmt_from_eh_lp (old_stmt);
2637 if (new_stmt_could_throw)
2639 add_stmt_to_eh_lp (new_stmt, lp_nr);
2649 /* Given a statement OLD_STMT in OLD_FUN and a duplicate statment NEW_STMT
2650 in NEW_FUN, copy the EH table data from OLD_STMT to NEW_STMT. The MAP
2651 operand is the return value of duplicate_eh_regions. */
2654 maybe_duplicate_eh_stmt_fn (struct function *new_fun, gimple new_stmt,
2655 struct function *old_fun, gimple old_stmt,
2656 struct pointer_map_t *map, int default_lp_nr)
2658 int old_lp_nr, new_lp_nr;
2661 if (!stmt_could_throw_p (new_stmt))
2664 old_lp_nr = lookup_stmt_eh_lp_fn (old_fun, old_stmt);
2667 if (default_lp_nr == 0)
2669 new_lp_nr = default_lp_nr;
2671 else if (old_lp_nr > 0)
2673 eh_landing_pad old_lp, new_lp;
2675 old_lp = VEC_index (eh_landing_pad, old_fun->eh->lp_array, old_lp_nr);
2676 slot = pointer_map_contains (map, old_lp);
2677 new_lp = (eh_landing_pad) *slot;
2678 new_lp_nr = new_lp->index;
2682 eh_region old_r, new_r;
2684 old_r = VEC_index (eh_region, old_fun->eh->region_array, -old_lp_nr);
2685 slot = pointer_map_contains (map, old_r);
2686 new_r = (eh_region) *slot;
2687 new_lp_nr = -new_r->index;
2690 add_stmt_to_eh_lp_fn (new_fun, new_stmt, new_lp_nr);
2694 /* Similar, but both OLD_STMT and NEW_STMT are within the current function,
2695 and thus no remapping is required. */
2698 maybe_duplicate_eh_stmt (gimple new_stmt, gimple old_stmt)
2702 if (!stmt_could_throw_p (new_stmt))
2705 lp_nr = lookup_stmt_eh_lp (old_stmt);
2709 add_stmt_to_eh_lp (new_stmt, lp_nr);
2713 /* Returns TRUE if oneh and twoh are exception handlers (gimple_try_cleanup of
2714 GIMPLE_TRY) that are similar enough to be considered the same. Currently
2715 this only handles handlers consisting of a single call, as that's the
2716 important case for C++: a destructor call for a particular object showing
2717 up in multiple handlers. */
2720 same_handler_p (gimple_seq oneh, gimple_seq twoh)
2722 gimple_stmt_iterator gsi;
2726 gsi = gsi_start (oneh);
2727 if (!gsi_one_before_end_p (gsi))
2729 ones = gsi_stmt (gsi);
2731 gsi = gsi_start (twoh);
2732 if (!gsi_one_before_end_p (gsi))
2734 twos = gsi_stmt (gsi);
2736 if (!is_gimple_call (ones)
2737 || !is_gimple_call (twos)
2738 || gimple_call_lhs (ones)
2739 || gimple_call_lhs (twos)
2740 || gimple_call_chain (ones)
2741 || gimple_call_chain (twos)
2742 || !gimple_call_same_target_p (ones, twos)
2743 || gimple_call_num_args (ones) != gimple_call_num_args (twos))
2746 for (ai = 0; ai < gimple_call_num_args (ones); ++ai)
2747 if (!operand_equal_p (gimple_call_arg (ones, ai),
2748 gimple_call_arg (twos, ai), 0))
2755 try { A() } finally { try { ~B() } catch { ~A() } }
2756 try { ... } finally { ~A() }
2758 try { A() } catch { ~B() }
2759 try { ~B() ... } finally { ~A() }
2761 This occurs frequently in C++, where A is a local variable and B is a
2762 temporary used in the initializer for A. */
2765 optimize_double_finally (gimple one, gimple two)
2768 gimple_stmt_iterator gsi;
2770 gsi = gsi_start (gimple_try_cleanup (one));
2771 if (!gsi_one_before_end_p (gsi))
2774 oneh = gsi_stmt (gsi);
2775 if (gimple_code (oneh) != GIMPLE_TRY
2776 || gimple_try_kind (oneh) != GIMPLE_TRY_CATCH)
2779 if (same_handler_p (gimple_try_cleanup (oneh), gimple_try_cleanup (two)))
2781 gimple_seq seq = gimple_try_eval (oneh);
2783 gimple_try_set_cleanup (one, seq);
2784 gimple_try_set_kind (one, GIMPLE_TRY_CATCH);
2785 seq = copy_gimple_seq_and_replace_locals (seq);
2786 gimple_seq_add_seq (&seq, gimple_try_eval (two));
2787 gimple_try_set_eval (two, seq);
2791 /* Perform EH refactoring optimizations that are simpler to do when code
2792 flow has been lowered but EH structures haven't. */
2795 refactor_eh_r (gimple_seq seq)
2797 gimple_stmt_iterator gsi;
2802 gsi = gsi_start (seq);
2806 if (gsi_end_p (gsi))
2809 two = gsi_stmt (gsi);
2812 && gimple_code (one) == GIMPLE_TRY
2813 && gimple_code (two) == GIMPLE_TRY
2814 && gimple_try_kind (one) == GIMPLE_TRY_FINALLY
2815 && gimple_try_kind (two) == GIMPLE_TRY_FINALLY)
2816 optimize_double_finally (one, two);
2818 switch (gimple_code (one))
2821 refactor_eh_r (gimple_try_eval (one));
2822 refactor_eh_r (gimple_try_cleanup (one));
2825 refactor_eh_r (gimple_catch_handler (one));
2827 case GIMPLE_EH_FILTER:
2828 refactor_eh_r (gimple_eh_filter_failure (one));
2843 refactor_eh_r (gimple_body (current_function_decl));
2848 gate_refactor_eh (void)
2850 return flag_exceptions != 0;
2853 struct gimple_opt_pass pass_refactor_eh =
2858 gate_refactor_eh, /* gate */
2859 refactor_eh, /* execute */
2862 0, /* static_pass_number */
2863 TV_TREE_EH, /* tv_id */
2864 PROP_gimple_lcf, /* properties_required */
2865 0, /* properties_provided */
2866 0, /* properties_destroyed */
2867 0, /* todo_flags_start */
2868 TODO_dump_func /* todo_flags_finish */
2872 /* At the end of gimple optimization, we can lower RESX. */
2875 lower_resx (basic_block bb, gimple stmt, struct pointer_map_t *mnt_map)
2878 eh_region src_r, dst_r;
2879 gimple_stmt_iterator gsi;
2884 lp_nr = lookup_stmt_eh_lp (stmt);
2886 dst_r = get_eh_region_from_lp_number (lp_nr);
2890 src_r = get_eh_region_from_number (gimple_resx_region (stmt));
2891 gsi = gsi_last_bb (bb);
2895 /* We can wind up with no source region when pass_cleanup_eh shows
2896 that there are no entries into an eh region and deletes it, but
2897 then the block that contains the resx isn't removed. This can
2898 happen without optimization when the switch statement created by
2899 lower_try_finally_switch isn't simplified to remove the eh case.
2901 Resolve this by expanding the resx node to an abort. */
2903 fn = implicit_built_in_decls[BUILT_IN_TRAP];
2904 x = gimple_build_call (fn, 0);
2905 gsi_insert_before (&gsi, x, GSI_SAME_STMT);
2907 while (EDGE_COUNT (bb->succs) > 0)
2908 remove_edge (EDGE_SUCC (bb, 0));
2912 /* When we have a destination region, we resolve this by copying
2913 the excptr and filter values into place, and changing the edge
2914 to immediately after the landing pad. */
2923 /* We are resuming into a MUST_NOT_CALL region. Expand a call to
2924 the failure decl into a new block, if needed. */
2925 gcc_assert (dst_r->type == ERT_MUST_NOT_THROW);
2927 slot = pointer_map_contains (mnt_map, dst_r);
2930 gimple_stmt_iterator gsi2;
2932 new_bb = create_empty_bb (bb);
2933 lab = gimple_block_label (new_bb);
2934 gsi2 = gsi_start_bb (new_bb);
2936 fn = dst_r->u.must_not_throw.failure_decl;
2937 x = gimple_build_call (fn, 0);
2938 gimple_set_location (x, dst_r->u.must_not_throw.failure_loc);
2939 gsi_insert_after (&gsi2, x, GSI_CONTINUE_LINKING);
2941 slot = pointer_map_insert (mnt_map, dst_r);
2947 new_bb = label_to_block (lab);
2950 gcc_assert (EDGE_COUNT (bb->succs) == 0);
2951 e = make_edge (bb, new_bb, EDGE_FALLTHRU);
2952 e->count = bb->count;
2953 e->probability = REG_BR_PROB_BASE;
2958 tree dst_nr = build_int_cst (integer_type_node, dst_r->index);
2960 fn = implicit_built_in_decls[BUILT_IN_EH_COPY_VALUES];
2961 src_nr = build_int_cst (integer_type_node, src_r->index);
2962 x = gimple_build_call (fn, 2, dst_nr, src_nr);
2963 gsi_insert_before (&gsi, x, GSI_SAME_STMT);
2965 /* Update the flags for the outgoing edge. */
2966 e = single_succ_edge (bb);
2967 gcc_assert (e->flags & EDGE_EH);
2968 e->flags = (e->flags & ~EDGE_EH) | EDGE_FALLTHRU;
2970 /* If there are no more EH users of the landing pad, delete it. */
2971 FOR_EACH_EDGE (e, ei, e->dest->preds)
2972 if (e->flags & EDGE_EH)
2976 eh_landing_pad lp = get_eh_landing_pad_from_number (lp_nr);
2977 remove_eh_landing_pad (lp);
2987 /* When we don't have a destination region, this exception escapes
2988 up the call chain. We resolve this by generating a call to the
2989 _Unwind_Resume library function. */
2991 /* The ARM EABI redefines _Unwind_Resume as __cxa_end_cleanup
2992 with no arguments for C++ and Java. Check for that. */
2993 if (src_r->use_cxa_end_cleanup)
2995 fn = implicit_built_in_decls[BUILT_IN_CXA_END_CLEANUP];
2996 x = gimple_build_call (fn, 0);
2997 gsi_insert_before (&gsi, x, GSI_SAME_STMT);
3001 fn = implicit_built_in_decls[BUILT_IN_EH_POINTER];
3002 src_nr = build_int_cst (integer_type_node, src_r->index);
3003 x = gimple_build_call (fn, 1, src_nr);
3004 var = create_tmp_var (ptr_type_node, NULL);
3005 var = make_ssa_name (var, x);
3006 gimple_call_set_lhs (x, var);
3007 gsi_insert_before (&gsi, x, GSI_SAME_STMT);
3009 fn = implicit_built_in_decls[BUILT_IN_UNWIND_RESUME];
3010 x = gimple_build_call (fn, 1, var);
3011 gsi_insert_before (&gsi, x, GSI_SAME_STMT);
3014 gcc_assert (EDGE_COUNT (bb->succs) == 0);
3017 gsi_remove (&gsi, true);
3023 execute_lower_resx (void)
3026 struct pointer_map_t *mnt_map;
3027 bool dominance_invalidated = false;
3028 bool any_rewritten = false;
3030 mnt_map = pointer_map_create ();
3034 gimple last = last_stmt (bb);
3035 if (last && is_gimple_resx (last))
3037 dominance_invalidated |= lower_resx (bb, last, mnt_map);
3038 any_rewritten = true;
3042 pointer_map_destroy (mnt_map);
3044 if (dominance_invalidated)
3046 free_dominance_info (CDI_DOMINATORS);
3047 free_dominance_info (CDI_POST_DOMINATORS);
3050 return any_rewritten ? TODO_update_ssa_only_virtuals : 0;
3054 gate_lower_resx (void)
3056 return flag_exceptions != 0;
3059 struct gimple_opt_pass pass_lower_resx =
3064 gate_lower_resx, /* gate */
3065 execute_lower_resx, /* execute */
3068 0, /* static_pass_number */
3069 TV_TREE_EH, /* tv_id */
3070 PROP_gimple_lcf, /* properties_required */
3071 0, /* properties_provided */
3072 0, /* properties_destroyed */
3073 0, /* todo_flags_start */
3074 TODO_dump_func | TODO_verify_flow /* todo_flags_finish */
3079 /* At the end of inlining, we can lower EH_DISPATCH. Return true when
3080 we have found some duplicate labels and removed some edges. */
3083 lower_eh_dispatch (basic_block src, gimple stmt)
3085 gimple_stmt_iterator gsi;
3090 bool redirected = false;
3092 region_nr = gimple_eh_dispatch_region (stmt);
3093 r = get_eh_region_from_number (region_nr);
3095 gsi = gsi_last_bb (src);
3101 VEC (tree, heap) *labels = NULL;
3102 tree default_label = NULL;
3106 struct pointer_set_t *seen_values = pointer_set_create ();
3108 /* Collect the labels for a switch. Zero the post_landing_pad
3109 field becase we'll no longer have anything keeping these labels
3110 in existance and the optimizer will be free to merge these
3112 for (c = r->u.eh_try.first_catch; c ; c = c->next_catch)
3114 tree tp_node, flt_node, lab = c->label;
3115 bool have_label = false;
3118 tp_node = c->type_list;
3119 flt_node = c->filter_list;
3121 if (tp_node == NULL)
3123 default_label = lab;
3128 /* Filter out duplicate labels that arise when this handler
3129 is shadowed by an earlier one. When no labels are
3130 attached to the handler anymore, we remove
3131 the corresponding edge and then we delete unreachable
3132 blocks at the end of this pass. */
3133 if (! pointer_set_contains (seen_values, TREE_VALUE (flt_node)))
3135 tree t = build_case_label (TREE_VALUE (flt_node),
3137 VEC_safe_push (tree, heap, labels, t);
3138 pointer_set_insert (seen_values, TREE_VALUE (flt_node));
3142 tp_node = TREE_CHAIN (tp_node);
3143 flt_node = TREE_CHAIN (flt_node);
3148 remove_edge (find_edge (src, label_to_block (lab)));
3153 /* Clean up the edge flags. */
3154 FOR_EACH_EDGE (e, ei, src->succs)
3156 if (e->flags & EDGE_FALLTHRU)
3158 /* If there was no catch-all, use the fallthru edge. */
3159 if (default_label == NULL)
3160 default_label = gimple_block_label (e->dest);
3161 e->flags &= ~EDGE_FALLTHRU;
3164 gcc_assert (default_label != NULL);
3166 /* Don't generate a switch if there's only a default case.
3167 This is common in the form of try { A; } catch (...) { B; }. */
3170 e = single_succ_edge (src);
3171 e->flags |= EDGE_FALLTHRU;
3175 fn = implicit_built_in_decls[BUILT_IN_EH_FILTER];
3176 x = gimple_build_call (fn, 1, build_int_cst (integer_type_node,
3178 filter = create_tmp_var (TREE_TYPE (TREE_TYPE (fn)), NULL);
3179 filter = make_ssa_name (filter, x);
3180 gimple_call_set_lhs (x, filter);
3181 gsi_insert_before (&gsi, x, GSI_SAME_STMT);
3183 /* Turn the default label into a default case. */
3184 default_label = build_case_label (NULL, NULL, default_label);
3185 sort_case_labels (labels);
3187 x = gimple_build_switch_vec (filter, default_label, labels);
3188 gsi_insert_before (&gsi, x, GSI_SAME_STMT);
3190 VEC_free (tree, heap, labels);
3192 pointer_set_destroy (seen_values);
3196 case ERT_ALLOWED_EXCEPTIONS:
3198 edge b_e = BRANCH_EDGE (src);
3199 edge f_e = FALLTHRU_EDGE (src);
3201 fn = implicit_built_in_decls[BUILT_IN_EH_FILTER];
3202 x = gimple_build_call (fn, 1, build_int_cst (integer_type_node,
3204 filter = create_tmp_var (TREE_TYPE (TREE_TYPE (fn)), NULL);
3205 filter = make_ssa_name (filter, x);
3206 gimple_call_set_lhs (x, filter);
3207 gsi_insert_before (&gsi, x, GSI_SAME_STMT);
3209 r->u.allowed.label = NULL;
3210 x = gimple_build_cond (EQ_EXPR, filter,
3211 build_int_cst (TREE_TYPE (filter),
3212 r->u.allowed.filter),
3213 NULL_TREE, NULL_TREE);
3214 gsi_insert_before (&gsi, x, GSI_SAME_STMT);
3216 b_e->flags = b_e->flags | EDGE_TRUE_VALUE;
3217 f_e->flags = (f_e->flags & ~EDGE_FALLTHRU) | EDGE_FALSE_VALUE;
3225 /* Replace the EH_DISPATCH with the SWITCH or COND generated above. */
3226 gsi_remove (&gsi, true);
3231 execute_lower_eh_dispatch (void)
3234 bool any_rewritten = false;
3235 bool redirected = false;
3237 assign_filter_values ();
3241 gimple last = last_stmt (bb);
3242 if (last && gimple_code (last) == GIMPLE_EH_DISPATCH)
3244 redirected |= lower_eh_dispatch (bb, last);
3245 any_rewritten = true;
3250 delete_unreachable_blocks ();
3251 return any_rewritten ? TODO_update_ssa_only_virtuals : 0;
3255 gate_lower_eh_dispatch (void)
3257 return cfun->eh->region_tree != NULL;
3260 struct gimple_opt_pass pass_lower_eh_dispatch =
3264 "ehdisp", /* name */
3265 gate_lower_eh_dispatch, /* gate */
3266 execute_lower_eh_dispatch, /* execute */
3269 0, /* static_pass_number */
3270 TV_TREE_EH, /* tv_id */
3271 PROP_gimple_lcf, /* properties_required */
3272 0, /* properties_provided */
3273 0, /* properties_destroyed */
3274 0, /* todo_flags_start */
3275 TODO_dump_func | TODO_verify_flow /* todo_flags_finish */
3279 /* Walk statements, see what regions are really referenced and remove
3280 those that are unused. */
3283 remove_unreachable_handlers (void)
3285 sbitmap r_reachable, lp_reachable;
3291 r_reachable = sbitmap_alloc (VEC_length (eh_region, cfun->eh->region_array));
3293 = sbitmap_alloc (VEC_length (eh_landing_pad, cfun->eh->lp_array));
3294 sbitmap_zero (r_reachable);
3295 sbitmap_zero (lp_reachable);
3299 gimple_stmt_iterator gsi = gsi_start_bb (bb);
3301 for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
3303 gimple stmt = gsi_stmt (gsi);
3304 lp_nr = lookup_stmt_eh_lp (stmt);
3306 /* Negative LP numbers are MUST_NOT_THROW regions which
3307 are not considered BB enders. */
3309 SET_BIT (r_reachable, -lp_nr);
3311 /* Positive LP numbers are real landing pads, are are BB enders. */
3314 gcc_assert (gsi_one_before_end_p (gsi));
3315 region = get_eh_region_from_lp_number (lp_nr);
3316 SET_BIT (r_reachable, region->index);
3317 SET_BIT (lp_reachable, lp_nr);
3320 /* Avoid removing regions referenced from RESX/EH_DISPATCH. */
3321 switch (gimple_code (stmt))
3324 SET_BIT (r_reachable, gimple_resx_region (stmt));
3326 case GIMPLE_EH_DISPATCH:
3327 SET_BIT (r_reachable, gimple_eh_dispatch_region (stmt));
3337 fprintf (dump_file, "Before removal of unreachable regions:\n");
3338 dump_eh_tree (dump_file, cfun);
3339 fprintf (dump_file, "Reachable regions: ");
3340 dump_sbitmap_file (dump_file, r_reachable);
3341 fprintf (dump_file, "Reachable landing pads: ");
3342 dump_sbitmap_file (dump_file, lp_reachable);
3346 VEC_iterate (eh_region, cfun->eh->region_array, r_nr, region); ++r_nr)
3347 if (region && !TEST_BIT (r_reachable, r_nr))
3350 fprintf (dump_file, "Removing unreachable region %d\n", r_nr);
3351 remove_eh_handler (region);
3355 VEC_iterate (eh_landing_pad, cfun->eh->lp_array, lp_nr, lp); ++lp_nr)
3356 if (lp && !TEST_BIT (lp_reachable, lp_nr))
3359 fprintf (dump_file, "Removing unreachable landing pad %d\n", lp_nr);
3360 remove_eh_landing_pad (lp);
3365 fprintf (dump_file, "\n\nAfter removal of unreachable regions:\n");
3366 dump_eh_tree (dump_file, cfun);
3367 fprintf (dump_file, "\n\n");
3370 sbitmap_free (r_reachable);
3371 sbitmap_free (lp_reachable);
3373 #ifdef ENABLE_CHECKING
3374 verify_eh_tree (cfun);
3378 /* Remove regions that do not have landing pads. This assumes
3379 that remove_unreachable_handlers has already been run, and
3380 that we've just manipulated the landing pads since then. */
3383 remove_unreachable_handlers_no_lp (void)
3388 for (i = 1; VEC_iterate (eh_region, cfun->eh->region_array, i, r); ++i)
3389 if (r && r->landing_pads == NULL && r->type != ERT_MUST_NOT_THROW)
3392 fprintf (dump_file, "Removing unreachable region %d\n", i);
3393 remove_eh_handler (r);
3397 /* Undo critical edge splitting on an EH landing pad. Earlier, we
3398 optimisticaly split all sorts of edges, including EH edges. The
3399 optimization passes in between may not have needed them; if not,
3400 we should undo the split.
3402 Recognize this case by having one EH edge incoming to the BB and
3403 one normal edge outgoing; BB should be empty apart from the
3404 post_landing_pad label.
3406 Note that this is slightly different from the empty handler case
3407 handled by cleanup_empty_eh, in that the actual handler may yet
3408 have actual code but the landing pad has been separated from the
3409 handler. As such, cleanup_empty_eh relies on this transformation
3410 having been done first. */
3413 unsplit_eh (eh_landing_pad lp)
3415 basic_block bb = label_to_block (lp->post_landing_pad);
3416 gimple_stmt_iterator gsi;
3419 /* Quickly check the edge counts on BB for singularity. */
3420 if (EDGE_COUNT (bb->preds) != 1 || EDGE_COUNT (bb->succs) != 1)
3422 e_in = EDGE_PRED (bb, 0);
3423 e_out = EDGE_SUCC (bb, 0);
3425 /* Input edge must be EH and output edge must be normal. */
3426 if ((e_in->flags & EDGE_EH) == 0 || (e_out->flags & EDGE_EH) != 0)
3429 /* The block must be empty except for the labels and debug insns. */
3430 gsi = gsi_after_labels (bb);
3431 if (!gsi_end_p (gsi) && is_gimple_debug (gsi_stmt (gsi)))
3432 gsi_next_nondebug (&gsi);
3433 if (!gsi_end_p (gsi))
3436 /* The destination block must not already have a landing pad
3437 for a different region. */
3438 for (gsi = gsi_start_bb (e_out->dest); !gsi_end_p (gsi); gsi_next (&gsi))
3440 gimple stmt = gsi_stmt (gsi);
3444 if (gimple_code (stmt) != GIMPLE_LABEL)
3446 lab = gimple_label_label (stmt);
3447 lp_nr = EH_LANDING_PAD_NR (lab);
3448 if (lp_nr && get_eh_region_from_lp_number (lp_nr) != lp->region)
3452 /* The new destination block must not already be a destination of
3453 the source block, lest we merge fallthru and eh edges and get
3454 all sorts of confused. */
3455 if (find_edge (e_in->src, e_out->dest))
3458 /* ??? We can get degenerate phis due to cfg cleanups. I would have
3459 thought this should have been cleaned up by a phicprop pass, but
3460 that doesn't appear to handle virtuals. Propagate by hand. */
3461 if (!gimple_seq_empty_p (phi_nodes (bb)))
3463 for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); )
3465 gimple use_stmt, phi = gsi_stmt (gsi);
3466 tree lhs = gimple_phi_result (phi);
3467 tree rhs = gimple_phi_arg_def (phi, 0);
3468 use_operand_p use_p;
3469 imm_use_iterator iter;
3471 FOR_EACH_IMM_USE_STMT (use_stmt, iter, lhs)
3473 FOR_EACH_IMM_USE_ON_STMT (use_p, iter)
3474 SET_USE (use_p, rhs);
3477 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (lhs))
3478 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (rhs) = 1;
3480 remove_phi_node (&gsi, true);
3484 if (dump_file && (dump_flags & TDF_DETAILS))
3485 fprintf (dump_file, "Unsplit EH landing pad %d to block %i.\n",
3486 lp->index, e_out->dest->index);
3488 /* Redirect the edge. Since redirect_eh_edge_1 expects to be moving
3489 a successor edge, humor it. But do the real CFG change with the
3490 predecessor of E_OUT in order to preserve the ordering of arguments
3491 to the PHI nodes in E_OUT->DEST. */
3492 redirect_eh_edge_1 (e_in, e_out->dest, false);
3493 redirect_edge_pred (e_out, e_in->src);
3494 e_out->flags = e_in->flags;
3495 e_out->probability = e_in->probability;
3496 e_out->count = e_in->count;
3502 /* Examine each landing pad block and see if it matches unsplit_eh. */
3505 unsplit_all_eh (void)
3507 bool changed = false;
3511 for (i = 1; VEC_iterate (eh_landing_pad, cfun->eh->lp_array, i, lp); ++i)
3513 changed |= unsplit_eh (lp);
3518 /* A subroutine of cleanup_empty_eh. Redirect all EH edges incoming
3519 to OLD_BB to NEW_BB; return true on success, false on failure.
3521 OLD_BB_OUT is the edge into NEW_BB from OLD_BB, so if we miss any
3522 PHI variables from OLD_BB we can pick them up from OLD_BB_OUT.
3523 Virtual PHIs may be deleted and marked for renaming. */
3526 cleanup_empty_eh_merge_phis (basic_block new_bb, basic_block old_bb,
3527 edge old_bb_out, bool change_region)
3529 gimple_stmt_iterator ngsi, ogsi;
3532 bitmap rename_virts;
3533 bitmap ophi_handled;
3535 FOR_EACH_EDGE (e, ei, old_bb->preds)
3536 redirect_edge_var_map_clear (e);
3538 ophi_handled = BITMAP_ALLOC (NULL);
3539 rename_virts = BITMAP_ALLOC (NULL);
3541 /* First, iterate through the PHIs on NEW_BB and set up the edge_var_map
3542 for the edges we're going to move. */
3543 for (ngsi = gsi_start_phis (new_bb); !gsi_end_p (ngsi); gsi_next (&ngsi))
3545 gimple ophi, nphi = gsi_stmt (ngsi);
3548 nresult = gimple_phi_result (nphi);
3549 nop = gimple_phi_arg_def (nphi, old_bb_out->dest_idx);
3551 /* Find the corresponding PHI in OLD_BB so we can forward-propagate
3552 the source ssa_name. */
3554 for (ogsi = gsi_start_phis (old_bb); !gsi_end_p (ogsi); gsi_next (&ogsi))
3556 ophi = gsi_stmt (ogsi);
3557 if (gimple_phi_result (ophi) == nop)
3562 /* If we did find the corresponding PHI, copy those inputs. */
3565 /* If NOP is used somewhere else beyond phis in new_bb, give up. */
3566 if (!has_single_use (nop))
3568 imm_use_iterator imm_iter;
3569 use_operand_p use_p;
3571 FOR_EACH_IMM_USE_FAST (use_p, imm_iter, nop)
3573 if (!gimple_debug_bind_p (USE_STMT (use_p))
3574 && (gimple_code (USE_STMT (use_p)) != GIMPLE_PHI
3575 || gimple_bb (USE_STMT (use_p)) != new_bb))
3579 bitmap_set_bit (ophi_handled, SSA_NAME_VERSION (nop));
3580 FOR_EACH_EDGE (e, ei, old_bb->preds)
3585 if ((e->flags & EDGE_EH) == 0)
3587 oop = gimple_phi_arg_def (ophi, e->dest_idx);
3588 oloc = gimple_phi_arg_location (ophi, e->dest_idx);
3589 redirect_edge_var_map_add (e, nresult, oop, oloc);
3592 /* If we didn't find the PHI, but it's a VOP, remember to rename
3593 it later, assuming all other tests succeed. */
3594 else if (!is_gimple_reg (nresult))
3595 bitmap_set_bit (rename_virts, SSA_NAME_VERSION (nresult));
3596 /* If we didn't find the PHI, and it's a real variable, we know
3597 from the fact that OLD_BB is tree_empty_eh_handler_p that the
3598 variable is unchanged from input to the block and we can simply
3599 re-use the input to NEW_BB from the OLD_BB_OUT edge. */
3603 = gimple_phi_arg_location (nphi, old_bb_out->dest_idx);
3604 FOR_EACH_EDGE (e, ei, old_bb->preds)
3605 redirect_edge_var_map_add (e, nresult, nop, nloc);
3609 /* Second, verify that all PHIs from OLD_BB have been handled. If not,
3610 we don't know what values from the other edges into NEW_BB to use. */
3611 for (ogsi = gsi_start_phis (old_bb); !gsi_end_p (ogsi); gsi_next (&ogsi))
3613 gimple ophi = gsi_stmt (ogsi);
3614 tree oresult = gimple_phi_result (ophi);
3615 if (!bitmap_bit_p (ophi_handled, SSA_NAME_VERSION (oresult)))
3619 /* At this point we know that the merge will succeed. Remove the PHI
3620 nodes for the virtuals that we want to rename. */
3621 if (!bitmap_empty_p (rename_virts))
3623 for (ngsi = gsi_start_phis (new_bb); !gsi_end_p (ngsi); )
3625 gimple nphi = gsi_stmt (ngsi);
3626 tree nresult = gimple_phi_result (nphi);
3627 if (bitmap_bit_p (rename_virts, SSA_NAME_VERSION (nresult)))
3629 mark_virtual_phi_result_for_renaming (nphi);
3630 remove_phi_node (&ngsi, true);
3637 /* Finally, move the edges and update the PHIs. */
3638 for (ei = ei_start (old_bb->preds); (e = ei_safe_edge (ei)); )
3639 if (e->flags & EDGE_EH)
3641 redirect_eh_edge_1 (e, new_bb, change_region);
3642 redirect_edge_succ (e, new_bb);
3643 flush_pending_stmts (e);
3648 BITMAP_FREE (ophi_handled);
3649 BITMAP_FREE (rename_virts);
3653 FOR_EACH_EDGE (e, ei, old_bb->preds)
3654 redirect_edge_var_map_clear (e);
3655 BITMAP_FREE (ophi_handled);
3656 BITMAP_FREE (rename_virts);
3660 /* A subroutine of cleanup_empty_eh. Move a landing pad LP from its
3661 old region to NEW_REGION at BB. */
3664 cleanup_empty_eh_move_lp (basic_block bb, edge e_out,
3665 eh_landing_pad lp, eh_region new_region)
3667 gimple_stmt_iterator gsi;
3670 for (pp = &lp->region->landing_pads; *pp != lp; pp = &(*pp)->next_lp)
3674 lp->region = new_region;
3675 lp->next_lp = new_region->landing_pads;
3676 new_region->landing_pads = lp;
3678 /* Delete the RESX that was matched within the empty handler block. */
3679 gsi = gsi_last_bb (bb);
3680 mark_virtual_ops_for_renaming (gsi_stmt (gsi));
3681 gsi_remove (&gsi, true);
3683 /* Clean up E_OUT for the fallthru. */
3684 e_out->flags = (e_out->flags & ~EDGE_EH) | EDGE_FALLTHRU;
3685 e_out->probability = REG_BR_PROB_BASE;
3688 /* A subroutine of cleanup_empty_eh. Handle more complex cases of
3689 unsplitting than unsplit_eh was prepared to handle, e.g. when
3690 multiple incoming edges and phis are involved. */
3693 cleanup_empty_eh_unsplit (basic_block bb, edge e_out, eh_landing_pad lp)
3695 gimple_stmt_iterator gsi;
3700 /* We really ought not have totally lost everything following
3701 a landing pad label. Given that BB is empty, there had better
3703 gcc_assert (e_out != NULL);
3705 /* The destination block must not already have a landing pad
3706 for a different region. */
3708 for (gsi = gsi_start_bb (e_out->dest); !gsi_end_p (gsi); gsi_next (&gsi))
3710 gimple stmt = gsi_stmt (gsi);
3713 if (gimple_code (stmt) != GIMPLE_LABEL)
3715 lab = gimple_label_label (stmt);
3716 lp_nr = EH_LANDING_PAD_NR (lab);
3717 if (lp_nr && get_eh_region_from_lp_number (lp_nr) != lp->region)
3721 /* The destination block must not be a regular successor for any
3722 of the preds of the landing pad. Thus, avoid turning
3732 which CFG verification would choke on. See PR45172. */
3733 FOR_EACH_EDGE (e, ei, bb->preds)
3734 if (find_edge (e->src, e_out->dest))
3737 /* Attempt to move the PHIs into the successor block. */
3738 if (cleanup_empty_eh_merge_phis (e_out->dest, bb, e_out, false))
3740 if (dump_file && (dump_flags & TDF_DETAILS))
3742 "Unsplit EH landing pad %d to block %i "
3743 "(via cleanup_empty_eh).\n",
3744 lp->index, e_out->dest->index);
3751 /* Return true if edge E_FIRST is part of an empty infinite loop
3752 or leads to such a loop through a series of single successor
3756 infinite_empty_loop_p (edge e_first)
3758 bool inf_loop = false;
3761 if (e_first->dest == e_first->src)
3764 e_first->src->aux = (void *) 1;
3765 for (e = e_first; single_succ_p (e->dest); e = single_succ_edge (e->dest))
3767 gimple_stmt_iterator gsi;
3773 e->dest->aux = (void *) 1;
3774 gsi = gsi_after_labels (e->dest);
3775 if (!gsi_end_p (gsi) && is_gimple_debug (gsi_stmt (gsi)))
3776 gsi_next_nondebug (&gsi);
3777 if (!gsi_end_p (gsi))
3780 e_first->src->aux = NULL;
3781 for (e = e_first; e->dest->aux; e = single_succ_edge (e->dest))
3782 e->dest->aux = NULL;
3787 /* Examine the block associated with LP to determine if it's an empty
3788 handler for its EH region. If so, attempt to redirect EH edges to
3789 an outer region. Return true the CFG was updated in any way. This
3790 is similar to jump forwarding, just across EH edges. */
3793 cleanup_empty_eh (eh_landing_pad lp)
3795 basic_block bb = label_to_block (lp->post_landing_pad);
3796 gimple_stmt_iterator gsi;
3798 eh_region new_region;
3801 bool has_non_eh_pred;
3804 /* There can be zero or one edges out of BB. This is the quickest test. */
3805 switch (EDGE_COUNT (bb->succs))
3811 e_out = EDGE_SUCC (bb, 0);
3816 gsi = gsi_after_labels (bb);
3818 /* Make sure to skip debug statements. */
3819 if (!gsi_end_p (gsi) && is_gimple_debug (gsi_stmt (gsi)))
3820 gsi_next_nondebug (&gsi);
3822 /* If the block is totally empty, look for more unsplitting cases. */
3823 if (gsi_end_p (gsi))
3825 /* For the degenerate case of an infinite loop bail out. */
3826 if (infinite_empty_loop_p (e_out))
3829 return cleanup_empty_eh_unsplit (bb, e_out, lp);
3832 /* The block should consist only of a single RESX statement. */
3833 resx = gsi_stmt (gsi);
3834 if (!is_gimple_resx (resx))
3836 gcc_assert (gsi_one_before_end_p (gsi));
3838 /* Determine if there are non-EH edges, or resx edges into the handler. */
3839 has_non_eh_pred = false;
3840 FOR_EACH_EDGE (e, ei, bb->preds)
3841 if (!(e->flags & EDGE_EH))
3842 has_non_eh_pred = true;
3844 /* Find the handler that's outer of the empty handler by looking at
3845 where the RESX instruction was vectored. */
3846 new_lp_nr = lookup_stmt_eh_lp (resx);
3847 new_region = get_eh_region_from_lp_number (new_lp_nr);
3849 /* If there's no destination region within the current function,
3850 redirection is trivial via removing the throwing statements from
3851 the EH region, removing the EH edges, and allowing the block
3852 to go unreachable. */
3853 if (new_region == NULL)
3855 gcc_assert (e_out == NULL);
3856 for (ei = ei_start (bb->preds); (e = ei_safe_edge (ei)); )
3857 if (e->flags & EDGE_EH)
3859 gimple stmt = last_stmt (e->src);
3860 remove_stmt_from_eh_lp (stmt);
3868 /* If the destination region is a MUST_NOT_THROW, allow the runtime
3869 to handle the abort and allow the blocks to go unreachable. */
3870 if (new_region->type == ERT_MUST_NOT_THROW)
3872 for (ei = ei_start (bb->preds); (e = ei_safe_edge (ei)); )
3873 if (e->flags & EDGE_EH)
3875 gimple stmt = last_stmt (e->src);
3876 remove_stmt_from_eh_lp (stmt);
3877 add_stmt_to_eh_lp (stmt, new_lp_nr);
3885 /* Try to redirect the EH edges and merge the PHIs into the destination
3886 landing pad block. If the merge succeeds, we'll already have redirected
3887 all the EH edges. The handler itself will go unreachable if there were
3889 if (cleanup_empty_eh_merge_phis (e_out->dest, bb, e_out, true))
3892 /* Finally, if all input edges are EH edges, then we can (potentially)
3893 reduce the number of transfers from the runtime by moving the landing
3894 pad from the original region to the new region. This is a win when
3895 we remove the last CLEANUP region along a particular exception
3896 propagation path. Since nothing changes except for the region with
3897 which the landing pad is associated, the PHI nodes do not need to be
3899 if (!has_non_eh_pred)
3901 cleanup_empty_eh_move_lp (bb, e_out, lp, new_region);
3902 if (dump_file && (dump_flags & TDF_DETAILS))
3903 fprintf (dump_file, "Empty EH handler %i moved to EH region %i.\n",
3904 lp->index, new_region->index);
3906 /* ??? The CFG didn't change, but we may have rendered the
3907 old EH region unreachable. Trigger a cleanup there. */
3914 if (dump_file && (dump_flags & TDF_DETAILS))
3915 fprintf (dump_file, "Empty EH handler %i removed.\n", lp->index);
3916 remove_eh_landing_pad (lp);
3920 /* Do a post-order traversal of the EH region tree. Examine each
3921 post_landing_pad block and see if we can eliminate it as empty. */
3924 cleanup_all_empty_eh (void)
3926 bool changed = false;
3930 for (i = 1; VEC_iterate (eh_landing_pad, cfun->eh->lp_array, i, lp); ++i)
3932 changed |= cleanup_empty_eh (lp);
3937 /* Perform cleanups and lowering of exception handling
3938 1) cleanups regions with handlers doing nothing are optimized out
3939 2) MUST_NOT_THROW regions that became dead because of 1) are optimized out
3940 3) Info about regions that are containing instructions, and regions
3941 reachable via local EH edges is collected
3942 4) Eh tree is pruned for regions no longer neccesary.
3944 TODO: Push MUST_NOT_THROW regions to the root of the EH tree.
3945 Unify those that have the same failure decl and locus.
3949 execute_cleanup_eh_1 (void)
3951 /* Do this first: unsplit_all_eh and cleanup_all_empty_eh can die
3952 looking up unreachable landing pads. */
3953 remove_unreachable_handlers ();
3955 /* Watch out for the region tree vanishing due to all unreachable. */
3956 if (cfun->eh->region_tree && optimize)
3958 bool changed = false;
3960 changed |= unsplit_all_eh ();
3961 changed |= cleanup_all_empty_eh ();
3965 free_dominance_info (CDI_DOMINATORS);
3966 free_dominance_info (CDI_POST_DOMINATORS);
3968 /* We delayed all basic block deletion, as we may have performed
3969 cleanups on EH edges while non-EH edges were still present. */
3970 delete_unreachable_blocks ();
3972 /* We manipulated the landing pads. Remove any region that no
3973 longer has a landing pad. */
3974 remove_unreachable_handlers_no_lp ();
3976 return TODO_cleanup_cfg | TODO_update_ssa_only_virtuals;
3984 execute_cleanup_eh (void)
3986 int ret = execute_cleanup_eh_1 ();
3988 /* If the function no longer needs an EH personality routine
3989 clear it. This exposes cross-language inlining opportunities
3990 and avoids references to a never defined personality routine. */
3991 if (DECL_FUNCTION_PERSONALITY (current_function_decl)
3992 && function_needs_eh_personality (cfun) != eh_personality_lang)
3993 DECL_FUNCTION_PERSONALITY (current_function_decl) = NULL_TREE;
3999 gate_cleanup_eh (void)
4001 return cfun->eh != NULL && cfun->eh->region_tree != NULL;
4004 struct gimple_opt_pass pass_cleanup_eh = {
4007 "ehcleanup", /* name */
4008 gate_cleanup_eh, /* gate */
4009 execute_cleanup_eh, /* execute */
4012 0, /* static_pass_number */
4013 TV_TREE_EH, /* tv_id */
4014 PROP_gimple_lcf, /* properties_required */
4015 0, /* properties_provided */
4016 0, /* properties_destroyed */
4017 0, /* todo_flags_start */
4018 TODO_dump_func /* todo_flags_finish */
4022 /* Verify that BB containing STMT as the last statement, has precisely the
4023 edge that make_eh_edges would create. */
4026 verify_eh_edges (gimple stmt)
4028 basic_block bb = gimple_bb (stmt);
4029 eh_landing_pad lp = NULL;
4034 lp_nr = lookup_stmt_eh_lp (stmt);
4036 lp = get_eh_landing_pad_from_number (lp_nr);
4039 FOR_EACH_EDGE (e, ei, bb->succs)
4041 if (e->flags & EDGE_EH)
4045 error ("BB %i has multiple EH edges", bb->index);
4057 error ("BB %i can not throw but has an EH edge", bb->index);
4063 if (!stmt_could_throw_p (stmt))
4065 error ("BB %i last statement has incorrectly set lp", bb->index);
4069 if (eh_edge == NULL)
4071 error ("BB %i is missing an EH edge", bb->index);
4075 if (eh_edge->dest != label_to_block (lp->post_landing_pad))
4077 error ("Incorrect EH edge %i->%i", bb->index, eh_edge->dest->index);
4084 /* Similarly, but handle GIMPLE_EH_DISPATCH specifically. */
4087 verify_eh_dispatch_edge (gimple stmt)
4091 basic_block src, dst;
4092 bool want_fallthru = true;
4096 r = get_eh_region_from_number (gimple_eh_dispatch_region (stmt));
4097 src = gimple_bb (stmt);
4099 FOR_EACH_EDGE (e, ei, src->succs)
4100 gcc_assert (e->aux == NULL);
4105 for (c = r->u.eh_try.first_catch; c ; c = c->next_catch)
4107 dst = label_to_block (c->label);
4108 e = find_edge (src, dst);
4111 error ("BB %i is missing an edge", src->index);
4116 /* A catch-all handler doesn't have a fallthru. */
4117 if (c->type_list == NULL)
4119 want_fallthru = false;
4125 case ERT_ALLOWED_EXCEPTIONS:
4126 dst = label_to_block (r->u.allowed.label);
4127 e = find_edge (src, dst);
4130 error ("BB %i is missing an edge", src->index);
4141 FOR_EACH_EDGE (e, ei, src->succs)
4143 if (e->flags & EDGE_FALLTHRU)
4145 if (fall_edge != NULL)
4147 error ("BB %i too many fallthru edges", src->index);
4156 error ("BB %i has incorrect edge", src->index);
4160 if ((fall_edge != NULL) ^ want_fallthru)
4162 error ("BB %i has incorrect fallthru edge", src->index);