1 /* Exception handling semantics and decomposition for trees.
2 Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009
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"
31 #include "tree-flow.h"
32 #include "tree-dump.h"
33 #include "tree-inline.h"
34 #include "tree-iterator.h"
35 #include "tree-pass.h"
37 #include "langhooks.h"
43 /* In some instances a tree and a gimple need to be stored in a same table,
44 i.e. in hash tables. This is a structure to do this. */
45 typedef union {tree
*tp
; tree t
; gimple g
;} treemple
;
47 /* Nonzero if we are using EH to handle cleanups. */
48 static int using_eh_for_cleanups_p
= 0;
51 using_eh_for_cleanups (void)
53 using_eh_for_cleanups_p
= 1;
56 /* Misc functions used in this file. */
58 /* Compare and hash for any structure which begins with a canonical
59 pointer. Assumes all pointers are interchangeable, which is sort
60 of already assumed by gcc elsewhere IIRC. */
63 struct_ptr_eq (const void *a
, const void *b
)
65 const void * const * x
= (const void * const *) a
;
66 const void * const * y
= (const void * const *) b
;
71 struct_ptr_hash (const void *a
)
73 const void * const * x
= (const void * const *) a
;
74 return (size_t)*x
>> 4;
78 /* Remember and lookup EH landing pad data for arbitrary statements.
79 Really this means any statement that could_throw_p. We could
80 stuff this information into the stmt_ann data structure, but:
82 (1) We absolutely rely on this information being kept until
83 we get to rtl. Once we're done with lowering here, if we lose
84 the information there's no way to recover it!
86 (2) There are many more statements that *cannot* throw as
87 compared to those that can. We should be saving some amount
88 of space by only allocating memory for those that can throw. */
90 /* Add statement T in function IFUN to landing pad NUM. */
93 add_stmt_to_eh_lp_fn (struct function
*ifun
, gimple t
, int num
)
95 struct throw_stmt_node
*n
;
98 gcc_assert (num
!= 0);
100 n
= GGC_NEW (struct throw_stmt_node
);
104 if (!get_eh_throw_stmt_table (ifun
))
105 set_eh_throw_stmt_table (ifun
, htab_create_ggc (31, struct_ptr_hash
,
109 slot
= htab_find_slot (get_eh_throw_stmt_table (ifun
), n
, INSERT
);
114 /* Add statement T in the current function (cfun) to EH landing pad NUM. */
117 add_stmt_to_eh_lp (gimple t
, int num
)
119 add_stmt_to_eh_lp_fn (cfun
, t
, num
);
122 /* Add statement T to the single EH landing pad in REGION. */
125 record_stmt_eh_region (eh_region region
, gimple t
)
129 if (region
->type
== ERT_MUST_NOT_THROW
)
130 add_stmt_to_eh_lp_fn (cfun
, t
, -region
->index
);
133 eh_landing_pad lp
= region
->landing_pads
;
135 lp
= gen_eh_landing_pad (region
);
137 gcc_assert (lp
->next_lp
== NULL
);
138 add_stmt_to_eh_lp_fn (cfun
, t
, lp
->index
);
143 /* Remove statement T in function IFUN from its EH landing pad. */
146 remove_stmt_from_eh_lp_fn (struct function
*ifun
, gimple t
)
148 struct throw_stmt_node dummy
;
151 if (!get_eh_throw_stmt_table (ifun
))
155 slot
= htab_find_slot (get_eh_throw_stmt_table (ifun
), &dummy
,
159 htab_clear_slot (get_eh_throw_stmt_table (ifun
), slot
);
167 /* Remove statement T in the current function (cfun) from its
171 remove_stmt_from_eh_lp (gimple t
)
173 return remove_stmt_from_eh_lp_fn (cfun
, t
);
176 /* Determine if statement T is inside an EH region in function IFUN.
177 Positive numbers indicate a landing pad index; negative numbers
178 indicate a MUST_NOT_THROW region index; zero indicates that the
179 statement is not recorded in the region table. */
182 lookup_stmt_eh_lp_fn (struct function
*ifun
, gimple t
)
184 struct throw_stmt_node
*p
, n
;
186 if (ifun
->eh
->throw_stmt_table
== NULL
)
190 p
= (struct throw_stmt_node
*) htab_find (ifun
->eh
->throw_stmt_table
, &n
);
191 return p
? p
->lp_nr
: 0;
194 /* Likewise, but always use the current function. */
197 lookup_stmt_eh_lp (gimple t
)
199 /* We can get called from initialized data when -fnon-call-exceptions
200 is on; prevent crash. */
203 return lookup_stmt_eh_lp_fn (cfun
, t
);
206 /* First pass of EH node decomposition. Build up a tree of GIMPLE_TRY_FINALLY
207 nodes and LABEL_DECL nodes. We will use this during the second phase to
208 determine if a goto leaves the body of a TRY_FINALLY_EXPR node. */
210 struct finally_tree_node
212 /* When storing a GIMPLE_TRY, we have to record a gimple. However
213 when deciding whether a GOTO to a certain LABEL_DECL (which is a
214 tree) leaves the TRY block, its necessary to record a tree in
215 this field. Thus a treemple is used. */
220 /* Note that this table is *not* marked GTY. It is short-lived. */
221 static htab_t finally_tree
;
224 record_in_finally_tree (treemple child
, gimple parent
)
226 struct finally_tree_node
*n
;
229 n
= XNEW (struct finally_tree_node
);
233 slot
= htab_find_slot (finally_tree
, n
, INSERT
);
239 collect_finally_tree (gimple stmt
, gimple region
);
241 /* Go through the gimple sequence. Works with collect_finally_tree to
242 record all GIMPLE_LABEL and GIMPLE_TRY statements. */
245 collect_finally_tree_1 (gimple_seq seq
, gimple region
)
247 gimple_stmt_iterator gsi
;
249 for (gsi
= gsi_start (seq
); !gsi_end_p (gsi
); gsi_next (&gsi
))
250 collect_finally_tree (gsi_stmt (gsi
), region
);
254 collect_finally_tree (gimple stmt
, gimple region
)
258 switch (gimple_code (stmt
))
261 temp
.t
= gimple_label_label (stmt
);
262 record_in_finally_tree (temp
, region
);
266 if (gimple_try_kind (stmt
) == GIMPLE_TRY_FINALLY
)
269 record_in_finally_tree (temp
, region
);
270 collect_finally_tree_1 (gimple_try_eval (stmt
), stmt
);
271 collect_finally_tree_1 (gimple_try_cleanup (stmt
), region
);
273 else if (gimple_try_kind (stmt
) == GIMPLE_TRY_CATCH
)
275 collect_finally_tree_1 (gimple_try_eval (stmt
), region
);
276 collect_finally_tree_1 (gimple_try_cleanup (stmt
), region
);
281 collect_finally_tree_1 (gimple_catch_handler (stmt
), region
);
284 case GIMPLE_EH_FILTER
:
285 collect_finally_tree_1 (gimple_eh_filter_failure (stmt
), region
);
289 /* A type, a decl, or some kind of statement that we're not
290 interested in. Don't walk them. */
296 /* Use the finally tree to determine if a jump from START to TARGET
297 would leave the try_finally node that START lives in. */
300 outside_finally_tree (treemple start
, gimple target
)
302 struct finally_tree_node n
, *p
;
307 p
= (struct finally_tree_node
*) htab_find (finally_tree
, &n
);
312 while (start
.g
!= target
);
317 /* Second pass of EH node decomposition. Actually transform the GIMPLE_TRY
318 nodes into a set of gotos, magic labels, and eh regions.
319 The eh region creation is straight-forward, but frobbing all the gotos
320 and such into shape isn't. */
322 /* The sequence into which we record all EH stuff. This will be
323 placed at the end of the function when we're all done. */
324 static gimple_seq eh_seq
;
326 /* Record whether an EH region contains something that can throw,
327 indexed by EH region number. */
328 static bitmap eh_region_may_contain_throw_map
;
330 /* The GOTO_QUEUE is is an array of GIMPLE_GOTO and GIMPLE_RETURN
331 statements that are seen to escape this GIMPLE_TRY_FINALLY node.
332 The idea is to record a gimple statement for everything except for
333 the conditionals, which get their labels recorded. Since labels are
334 of type 'tree', we need this node to store both gimple and tree
335 objects. REPL_STMT is the sequence used to replace the goto/return
336 statement. CONT_STMT is used to store the statement that allows
337 the return/goto to jump to the original destination. */
339 struct goto_queue_node
342 gimple_seq repl_stmt
;
345 /* This is used when index >= 0 to indicate that stmt is a label (as
346 opposed to a goto stmt). */
350 /* State of the world while lowering. */
354 /* What's "current" while constructing the eh region tree. These
355 correspond to variables of the same name in cfun->eh, which we
356 don't have easy access to. */
357 eh_region cur_region
;
359 /* What's "current" for the purposes of __builtin_eh_pointer. For
360 a CATCH, this is the associated TRY. For an EH_FILTER, this is
361 the associated ALLOWED_EXCEPTIONS, etc. */
362 eh_region ehp_region
;
364 /* Processing of TRY_FINALLY requires a bit more state. This is
365 split out into a separate structure so that we don't have to
366 copy so much when processing other nodes. */
367 struct leh_tf_state
*tf
;
372 /* Pointer to the GIMPLE_TRY_FINALLY node under discussion. The
373 try_finally_expr is the original GIMPLE_TRY_FINALLY. We need to retain
374 this so that outside_finally_tree can reliably reference the tree used
375 in the collect_finally_tree data structures. */
376 gimple try_finally_expr
;
379 /* While lowering a top_p usually it is expanded into multiple statements,
380 thus we need the following field to store them. */
381 gimple_seq top_p_seq
;
383 /* The state outside this try_finally node. */
384 struct leh_state
*outer
;
386 /* The exception region created for it. */
389 /* The goto queue. */
390 struct goto_queue_node
*goto_queue
;
391 size_t goto_queue_size
;
392 size_t goto_queue_active
;
394 /* Pointer map to help in searching goto_queue when it is large. */
395 struct pointer_map_t
*goto_queue_map
;
397 /* The set of unique labels seen as entries in the goto queue. */
398 VEC(tree
,heap
) *dest_array
;
400 /* A label to be added at the end of the completed transformed
401 sequence. It will be set if may_fallthru was true *at one time*,
402 though subsequent transformations may have cleared that flag. */
405 /* True if it is possible to fall out the bottom of the try block.
406 Cleared if the fallthru is converted to a goto. */
409 /* True if any entry in goto_queue is a GIMPLE_RETURN. */
412 /* True if the finally block can receive an exception edge.
413 Cleared if the exception case is handled by code duplication. */
417 static gimple_seq
lower_eh_must_not_throw (struct leh_state
*, gimple
);
419 /* Search for STMT in the goto queue. Return the replacement,
420 or null if the statement isn't in the queue. */
422 #define LARGE_GOTO_QUEUE 20
424 static void lower_eh_constructs_1 (struct leh_state
*state
, gimple_seq seq
);
427 find_goto_replacement (struct leh_tf_state
*tf
, treemple stmt
)
432 if (tf
->goto_queue_active
< LARGE_GOTO_QUEUE
)
434 for (i
= 0; i
< tf
->goto_queue_active
; i
++)
435 if ( tf
->goto_queue
[i
].stmt
.g
== stmt
.g
)
436 return tf
->goto_queue
[i
].repl_stmt
;
440 /* If we have a large number of entries in the goto_queue, create a
441 pointer map and use that for searching. */
443 if (!tf
->goto_queue_map
)
445 tf
->goto_queue_map
= pointer_map_create ();
446 for (i
= 0; i
< tf
->goto_queue_active
; i
++)
448 slot
= pointer_map_insert (tf
->goto_queue_map
,
449 tf
->goto_queue
[i
].stmt
.g
);
450 gcc_assert (*slot
== NULL
);
451 *slot
= &tf
->goto_queue
[i
];
455 slot
= pointer_map_contains (tf
->goto_queue_map
, stmt
.g
);
457 return (((struct goto_queue_node
*) *slot
)->repl_stmt
);
462 /* A subroutine of replace_goto_queue_1. Handles the sub-clauses of a
463 lowered GIMPLE_COND. If, by chance, the replacement is a simple goto,
464 then we can just splat it in, otherwise we add the new stmts immediately
465 after the GIMPLE_COND and redirect. */
468 replace_goto_queue_cond_clause (tree
*tp
, struct leh_tf_state
*tf
,
469 gimple_stmt_iterator
*gsi
)
474 location_t loc
= gimple_location (gsi_stmt (*gsi
));
477 new_seq
= find_goto_replacement (tf
, temp
);
481 if (gimple_seq_singleton_p (new_seq
)
482 && gimple_code (gimple_seq_first_stmt (new_seq
)) == GIMPLE_GOTO
)
484 *tp
= gimple_goto_dest (gimple_seq_first_stmt (new_seq
));
488 label
= create_artificial_label (loc
);
489 /* Set the new label for the GIMPLE_COND */
492 gsi_insert_after (gsi
, gimple_build_label (label
), GSI_CONTINUE_LINKING
);
493 gsi_insert_seq_after (gsi
, gimple_seq_copy (new_seq
), GSI_CONTINUE_LINKING
);
496 /* The real work of replace_goto_queue. Returns with TSI updated to
497 point to the next statement. */
499 static void replace_goto_queue_stmt_list (gimple_seq
, struct leh_tf_state
*);
502 replace_goto_queue_1 (gimple stmt
, struct leh_tf_state
*tf
,
503 gimple_stmt_iterator
*gsi
)
509 switch (gimple_code (stmt
))
514 seq
= find_goto_replacement (tf
, temp
);
517 gsi_insert_seq_before (gsi
, gimple_seq_copy (seq
), GSI_SAME_STMT
);
518 gsi_remove (gsi
, false);
524 replace_goto_queue_cond_clause (gimple_op_ptr (stmt
, 2), tf
, gsi
);
525 replace_goto_queue_cond_clause (gimple_op_ptr (stmt
, 3), tf
, gsi
);
529 replace_goto_queue_stmt_list (gimple_try_eval (stmt
), tf
);
530 replace_goto_queue_stmt_list (gimple_try_cleanup (stmt
), tf
);
533 replace_goto_queue_stmt_list (gimple_catch_handler (stmt
), tf
);
535 case GIMPLE_EH_FILTER
:
536 replace_goto_queue_stmt_list (gimple_eh_filter_failure (stmt
), tf
);
540 /* These won't have gotos in them. */
547 /* A subroutine of replace_goto_queue. Handles GIMPLE_SEQ. */
550 replace_goto_queue_stmt_list (gimple_seq seq
, struct leh_tf_state
*tf
)
552 gimple_stmt_iterator gsi
= gsi_start (seq
);
554 while (!gsi_end_p (gsi
))
555 replace_goto_queue_1 (gsi_stmt (gsi
), tf
, &gsi
);
558 /* Replace all goto queue members. */
561 replace_goto_queue (struct leh_tf_state
*tf
)
563 if (tf
->goto_queue_active
== 0)
565 replace_goto_queue_stmt_list (tf
->top_p_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);
649 /* For any GIMPLE_GOTO or GIMPLE_RETURN, decide whether it leaves a try_finally
650 node, and if so record that fact in the goto queue associated with that
654 maybe_record_in_goto_queue (struct leh_state
*state
, gimple stmt
)
656 struct leh_tf_state
*tf
= state
->tf
;
662 switch (gimple_code (stmt
))
665 new_stmt
.tp
= gimple_op_ptr (stmt
, 2);
666 record_in_goto_queue_label (tf
, new_stmt
, gimple_cond_true_label (stmt
));
667 new_stmt
.tp
= gimple_op_ptr (stmt
, 3);
668 record_in_goto_queue_label (tf
, new_stmt
, gimple_cond_false_label (stmt
));
672 record_in_goto_queue_label (tf
, new_stmt
, gimple_goto_dest (stmt
));
676 tf
->may_return
= true;
678 record_in_goto_queue (tf
, new_stmt
, -1, false);
687 #ifdef ENABLE_CHECKING
688 /* We do not process GIMPLE_SWITCHes for now. As long as the original source
689 was in fact structured, and we've not yet done jump threading, then none
690 of the labels will leave outer GIMPLE_TRY_FINALLY nodes. Verify this. */
693 verify_norecord_switch_expr (struct leh_state
*state
, gimple switch_expr
)
695 struct leh_tf_state
*tf
= state
->tf
;
701 n
= gimple_switch_num_labels (switch_expr
);
703 for (i
= 0; i
< n
; ++i
)
706 tree lab
= CASE_LABEL (gimple_switch_label (switch_expr
, i
));
708 gcc_assert (!outside_finally_tree (temp
, tf
->try_finally_expr
));
712 #define verify_norecord_switch_expr(state, switch_expr)
715 /* Redirect a RETURN_EXPR pointed to by STMT_P to FINLAB. Place in CONT_P
716 whatever is needed to finish the return. If MOD is non-null, insert it
717 before the new branch. RETURN_VALUE_P is a cache containing a temporary
718 variable to be used in manipulating the value returned from the function. */
721 do_return_redirection (struct goto_queue_node
*q
, tree finlab
, gimple_seq mod
,
722 tree
*return_value_p
)
727 /* In the case of a return, the queue node must be a gimple statement. */
728 gcc_assert (!q
->is_label
);
730 ret_expr
= gimple_return_retval (q
->stmt
.g
);
734 if (!*return_value_p
)
735 *return_value_p
= ret_expr
;
737 gcc_assert (*return_value_p
== ret_expr
);
738 q
->cont_stmt
= q
->stmt
.g
;
739 /* The nasty part about redirecting the return value is that the
740 return value itself is to be computed before the FINALLY block
754 should return 0, not 1. Arrange for this to happen by copying
755 computed the return value into a local temporary. This also
756 allows us to redirect multiple return statements through the
757 same destination block; whether this is a net win or not really
758 depends, I guess, but it does make generation of the switch in
759 lower_try_finally_switch easier. */
761 if (TREE_CODE (ret_expr
) == RESULT_DECL
)
763 if (!*return_value_p
)
764 *return_value_p
= ret_expr
;
766 gcc_assert (*return_value_p
== ret_expr
);
767 q
->cont_stmt
= q
->stmt
.g
;
773 /* If we don't return a value, all return statements are the same. */
774 q
->cont_stmt
= q
->stmt
.g
;
777 q
->repl_stmt
= gimple_seq_alloc ();
780 gimple_seq_add_seq (&q
->repl_stmt
, mod
);
782 x
= gimple_build_goto (finlab
);
783 gimple_seq_add_stmt (&q
->repl_stmt
, x
);
786 /* Similar, but easier, for GIMPLE_GOTO. */
789 do_goto_redirection (struct goto_queue_node
*q
, tree finlab
, gimple_seq mod
,
790 struct leh_tf_state
*tf
)
794 gcc_assert (q
->is_label
);
796 q
->repl_stmt
= gimple_seq_alloc ();
798 q
->cont_stmt
= gimple_build_goto (VEC_index (tree
, tf
->dest_array
, q
->index
));
801 gimple_seq_add_seq (&q
->repl_stmt
, mod
);
803 x
= gimple_build_goto (finlab
);
804 gimple_seq_add_stmt (&q
->repl_stmt
, x
);
807 /* Emit a standard landing pad sequence into SEQ for REGION. */
810 emit_post_landing_pad (gimple_seq
*seq
, eh_region region
)
812 eh_landing_pad lp
= region
->landing_pads
;
816 lp
= gen_eh_landing_pad (region
);
818 lp
->post_landing_pad
= create_artificial_label (UNKNOWN_LOCATION
);
819 EH_LANDING_PAD_NR (lp
->post_landing_pad
) = lp
->index
;
821 x
= gimple_build_label (lp
->post_landing_pad
);
822 gimple_seq_add_stmt (seq
, x
);
825 /* Emit a RESX statement into SEQ for REGION. */
828 emit_resx (gimple_seq
*seq
, eh_region region
)
830 gimple x
= gimple_build_resx (region
->index
);
831 gimple_seq_add_stmt (seq
, x
);
833 record_stmt_eh_region (region
->outer
, x
);
836 /* Emit an EH_DISPATCH statement into SEQ for REGION. */
839 emit_eh_dispatch (gimple_seq
*seq
, eh_region region
)
841 gimple x
= gimple_build_eh_dispatch (region
->index
);
842 gimple_seq_add_stmt (seq
, x
);
845 /* Note that the current EH region may contain a throw, or a
846 call to a function which itself may contain a throw. */
849 note_eh_region_may_contain_throw (eh_region region
)
851 while (!bitmap_bit_p (eh_region_may_contain_throw_map
, region
->index
))
853 bitmap_set_bit (eh_region_may_contain_throw_map
, region
->index
);
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 lang_protect_cleanup_actions
956 returns non-null, then the language requires that the exception path out
957 of a try_finally be treated specially. To wit: the code within the
958 finally block may not itself throw an exception. We have two choices here.
959 First we can duplicate the finally block and wrap it in a must_not_throw
960 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_protect_cleanup_actions
== NULL
)
989 protect_cleanup_actions
= lang_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 (NULL
, fallthru_index
));
1340 gimple_seq_add_stmt (&tf
->top_p_seq
, x
);
1342 last_case
= build3 (CASE_LABEL_EXPR
, void_type_node
,
1343 build_int_cst (NULL
, fallthru_index
),
1344 NULL
, create_artificial_label (tf_loc
));
1345 VEC_quick_push (tree
, case_label_vec
, last_case
);
1348 x
= gimple_build_label (CASE_LABEL (last_case
));
1349 gimple_seq_add_stmt (&switch_body
, x
);
1351 tmp
= lower_try_finally_fallthru_label (tf
);
1352 x
= gimple_build_goto (tmp
);
1353 gimple_seq_add_stmt (&switch_body
, x
);
1358 emit_post_landing_pad (&eh_seq
, tf
->region
);
1360 x
= gimple_build_assign (finally_tmp
,
1361 build_int_cst (NULL
, eh_index
));
1362 gimple_seq_add_stmt (&eh_seq
, x
);
1364 x
= gimple_build_goto (finally_label
);
1365 gimple_seq_add_stmt (&eh_seq
, x
);
1367 last_case
= build3 (CASE_LABEL_EXPR
, void_type_node
,
1368 build_int_cst (NULL
, eh_index
),
1369 NULL
, create_artificial_label (tf_loc
));
1370 VEC_quick_push (tree
, case_label_vec
, last_case
);
1373 x
= gimple_build_label (CASE_LABEL (last_case
));
1374 gimple_seq_add_stmt (&eh_seq
, x
);
1375 emit_resx (&eh_seq
, tf
->region
);
1378 x
= gimple_build_label (finally_label
);
1379 gimple_seq_add_stmt (&tf
->top_p_seq
, x
);
1381 gimple_seq_add_seq (&tf
->top_p_seq
, finally
);
1383 /* Redirect each incoming goto edge. */
1385 qe
= q
+ tf
->goto_queue_active
;
1386 j
= last_case_index
+ tf
->may_return
;
1387 /* Prepare the assignments to finally_tmp that are executed upon the
1388 entrance through a particular edge. */
1393 unsigned int case_index
;
1395 mod
= gimple_seq_alloc ();
1399 x
= gimple_build_assign (finally_tmp
,
1400 build_int_cst (NULL
, return_index
));
1401 gimple_seq_add_stmt (&mod
, x
);
1402 do_return_redirection (q
, finally_label
, mod
, &return_val
);
1403 switch_id
= return_index
;
1407 x
= gimple_build_assign (finally_tmp
,
1408 build_int_cst (NULL
, q
->index
));
1409 gimple_seq_add_stmt (&mod
, x
);
1410 do_goto_redirection (q
, finally_label
, mod
, tf
);
1411 switch_id
= q
->index
;
1414 case_index
= j
+ q
->index
;
1415 if (VEC_length (tree
, case_label_vec
) <= case_index
1416 || !VEC_index (tree
, case_label_vec
, case_index
))
1420 case_lab
= build3 (CASE_LABEL_EXPR
, void_type_node
,
1421 build_int_cst (NULL
, switch_id
),
1423 /* We store the cont_stmt in the pointer map, so that we can recover
1424 it in the loop below. We don't create the new label while
1425 walking the goto_queue because pointers don't offer a stable
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
++)
1440 last_case
= VEC_index (tree
, case_label_vec
, j
);
1442 gcc_assert (last_case
);
1443 gcc_assert (cont_map
);
1445 slot
= pointer_map_contains (cont_map
, last_case
);
1446 /* As the comment above suggests, CASE_LABEL (last_case) was just a
1447 placeholder, it does not store an actual label, yet. */
1449 cont_stmt
= *(gimple
*) slot
;
1451 label
= create_artificial_label (tf_loc
);
1452 CASE_LABEL (last_case
) = label
;
1454 x
= gimple_build_label (label
);
1455 gimple_seq_add_stmt (&switch_body
, x
);
1456 gimple_seq_add_stmt (&switch_body
, cont_stmt
);
1457 maybe_record_in_goto_queue (state
, cont_stmt
);
1460 pointer_map_destroy (cont_map
);
1462 replace_goto_queue (tf
);
1464 /* Make sure that the last case is the default label, as one is required.
1465 Then sort the labels, which is also required in GIMPLE. */
1466 CASE_LOW (last_case
) = NULL
;
1467 sort_case_labels (case_label_vec
);
1469 /* Build the switch statement, setting last_case to be the default
1471 switch_stmt
= gimple_build_switch_vec (finally_tmp
, last_case
,
1473 gimple_set_location (switch_stmt
, finally_loc
);
1475 /* Need to link SWITCH_STMT after running replace_goto_queue
1476 due to not wanting to process the same goto stmts twice. */
1477 gimple_seq_add_stmt (&tf
->top_p_seq
, switch_stmt
);
1478 gimple_seq_add_seq (&tf
->top_p_seq
, switch_body
);
1481 /* Decide whether or not we are going to duplicate the finally block.
1482 There are several considerations.
1484 First, if this is Java, then the finally block contains code
1485 written by the user. It has line numbers associated with it,
1486 so duplicating the block means it's difficult to set a breakpoint.
1487 Since controlling code generation via -g is verboten, we simply
1488 never duplicate code without optimization.
1490 Second, we'd like to prevent egregious code growth. One way to
1491 do this is to estimate the size of the finally block, multiply
1492 that by the number of copies we'd need to make, and compare against
1493 the estimate of the size of the switch machinery we'd have to add. */
1496 decide_copy_try_finally (int ndests
, gimple_seq finally
)
1498 int f_estimate
, sw_estimate
;
1503 /* Finally estimate N times, plus N gotos. */
1504 f_estimate
= count_insns_seq (finally
, &eni_size_weights
);
1505 f_estimate
= (f_estimate
+ 1) * ndests
;
1507 /* Switch statement (cost 10), N variable assignments, N gotos. */
1508 sw_estimate
= 10 + 2 * ndests
;
1510 /* Optimize for size clearly wants our best guess. */
1511 if (optimize_function_for_size_p (cfun
))
1512 return f_estimate
< sw_estimate
;
1514 /* ??? These numbers are completely made up so far. */
1516 return f_estimate
< 100 || f_estimate
< sw_estimate
* 2;
1518 return f_estimate
< 40 || f_estimate
* 2 < sw_estimate
* 3;
1522 /* A subroutine of lower_eh_constructs_1. Lower a GIMPLE_TRY_FINALLY nodes
1523 to a sequence of labels and blocks, plus the exception region trees
1524 that record all the magic. This is complicated by the need to
1525 arrange for the FINALLY block to be executed on all exits. */
1528 lower_try_finally (struct leh_state
*state
, gimple tp
)
1530 struct leh_tf_state this_tf
;
1531 struct leh_state this_state
;
1534 /* Process the try block. */
1536 memset (&this_tf
, 0, sizeof (this_tf
));
1537 this_tf
.try_finally_expr
= tp
;
1539 this_tf
.outer
= state
;
1540 if (using_eh_for_cleanups_p
)
1541 this_tf
.region
= gen_eh_region_cleanup (state
->cur_region
);
1543 this_tf
.region
= NULL
;
1545 this_state
.cur_region
= this_tf
.region
;
1546 this_state
.ehp_region
= state
->ehp_region
;
1547 this_state
.tf
= &this_tf
;
1549 lower_eh_constructs_1 (&this_state
, gimple_try_eval(tp
));
1551 /* Determine if the try block is escaped through the bottom. */
1552 this_tf
.may_fallthru
= gimple_seq_may_fallthru (gimple_try_eval (tp
));
1554 /* Determine if any exceptions are possible within the try block. */
1555 if (using_eh_for_cleanups_p
)
1556 this_tf
.may_throw
= eh_region_may_contain_throw (this_tf
.region
);
1557 if (this_tf
.may_throw
)
1558 honor_protect_cleanup_actions (state
, &this_state
, &this_tf
);
1560 /* Determine how many edges (still) reach the finally block. Or rather,
1561 how many destinations are reached by the finally block. Use this to
1562 determine how we process the finally block itself. */
1564 ndests
= VEC_length (tree
, this_tf
.dest_array
);
1565 ndests
+= this_tf
.may_fallthru
;
1566 ndests
+= this_tf
.may_return
;
1567 ndests
+= this_tf
.may_throw
;
1569 /* If the FINALLY block is not reachable, dike it out. */
1572 gimple_seq_add_seq (&this_tf
.top_p_seq
, gimple_try_eval (tp
));
1573 gimple_try_set_cleanup (tp
, NULL
);
1575 /* If the finally block doesn't fall through, then any destination
1576 we might try to impose there isn't reached either. There may be
1577 some minor amount of cleanup and redirection still needed. */
1578 else if (!gimple_seq_may_fallthru (gimple_try_cleanup (tp
)))
1579 lower_try_finally_nofallthru (state
, &this_tf
);
1581 /* We can easily special-case redirection to a single destination. */
1582 else if (ndests
== 1)
1583 lower_try_finally_onedest (state
, &this_tf
);
1584 else if (decide_copy_try_finally (ndests
, gimple_try_cleanup (tp
)))
1585 lower_try_finally_copy (state
, &this_tf
);
1587 lower_try_finally_switch (state
, &this_tf
);
1589 /* If someone requested we add a label at the end of the transformed
1591 if (this_tf
.fallthru_label
)
1593 /* This must be reached only if ndests == 0. */
1594 gimple x
= gimple_build_label (this_tf
.fallthru_label
);
1595 gimple_seq_add_stmt (&this_tf
.top_p_seq
, x
);
1598 VEC_free (tree
, heap
, this_tf
.dest_array
);
1599 if (this_tf
.goto_queue
)
1600 free (this_tf
.goto_queue
);
1601 if (this_tf
.goto_queue_map
)
1602 pointer_map_destroy (this_tf
.goto_queue_map
);
1604 return this_tf
.top_p_seq
;
1607 /* A subroutine of lower_eh_constructs_1. Lower a GIMPLE_TRY_CATCH with a
1608 list of GIMPLE_CATCH to a sequence of labels and blocks, plus the
1609 exception region trees that records all the magic. */
1612 lower_catch (struct leh_state
*state
, gimple tp
)
1614 eh_region try_region
= NULL
;
1615 struct leh_state this_state
= *state
;
1616 gimple_stmt_iterator gsi
;
1620 location_t try_catch_loc
= gimple_location (tp
);
1622 if (flag_exceptions
)
1624 try_region
= gen_eh_region_try (state
->cur_region
);
1625 this_state
.cur_region
= try_region
;
1628 lower_eh_constructs_1 (&this_state
, gimple_try_eval (tp
));
1630 if (!eh_region_may_contain_throw (try_region
))
1631 return gimple_try_eval (tp
);
1634 emit_eh_dispatch (&new_seq
, try_region
);
1635 emit_resx (&new_seq
, try_region
);
1637 this_state
.cur_region
= state
->cur_region
;
1638 this_state
.ehp_region
= try_region
;
1641 for (gsi
= gsi_start (gimple_try_cleanup (tp
));
1649 gcatch
= gsi_stmt (gsi
);
1650 c
= gen_eh_region_catch (try_region
, gimple_catch_types (gcatch
));
1652 handler
= gimple_catch_handler (gcatch
);
1653 lower_eh_constructs_1 (&this_state
, handler
);
1655 c
->label
= create_artificial_label (UNKNOWN_LOCATION
);
1656 x
= gimple_build_label (c
->label
);
1657 gimple_seq_add_stmt (&new_seq
, x
);
1659 gimple_seq_add_seq (&new_seq
, handler
);
1661 if (gimple_seq_may_fallthru (new_seq
))
1664 out_label
= create_artificial_label (try_catch_loc
);
1666 x
= gimple_build_goto (out_label
);
1667 gimple_seq_add_stmt (&new_seq
, x
);
1673 gimple_try_set_cleanup (tp
, new_seq
);
1675 return frob_into_branch_around (tp
, try_region
, out_label
);
1678 /* A subroutine of lower_eh_constructs_1. Lower a GIMPLE_TRY with a
1679 GIMPLE_EH_FILTER to a sequence of labels and blocks, plus the exception
1680 region trees that record all the magic. */
1683 lower_eh_filter (struct leh_state
*state
, gimple tp
)
1685 struct leh_state this_state
= *state
;
1686 eh_region this_region
= NULL
;
1690 inner
= gimple_seq_first_stmt (gimple_try_cleanup (tp
));
1692 if (flag_exceptions
)
1694 this_region
= gen_eh_region_allowed (state
->cur_region
,
1695 gimple_eh_filter_types (inner
));
1696 this_state
.cur_region
= this_region
;
1699 lower_eh_constructs_1 (&this_state
, gimple_try_eval (tp
));
1701 if (!eh_region_may_contain_throw (this_region
))
1702 return gimple_try_eval (tp
);
1705 this_state
.cur_region
= state
->cur_region
;
1706 this_state
.ehp_region
= this_region
;
1708 emit_eh_dispatch (&new_seq
, this_region
);
1709 emit_resx (&new_seq
, this_region
);
1711 this_region
->u
.allowed
.label
= create_artificial_label (UNKNOWN_LOCATION
);
1712 x
= gimple_build_label (this_region
->u
.allowed
.label
);
1713 gimple_seq_add_stmt (&new_seq
, x
);
1715 lower_eh_constructs_1 (&this_state
, gimple_eh_filter_failure (inner
));
1716 gimple_seq_add_seq (&new_seq
, gimple_eh_filter_failure (inner
));
1718 gimple_try_set_cleanup (tp
, new_seq
);
1720 return frob_into_branch_around (tp
, this_region
, NULL
);
1723 /* A subroutine of lower_eh_constructs_1. Lower a GIMPLE_TRY with
1724 an GIMPLE_EH_MUST_NOT_THROW to a sequence of labels and blocks,
1725 plus the exception region trees that record all the magic. */
1728 lower_eh_must_not_throw (struct leh_state
*state
, gimple tp
)
1730 struct leh_state this_state
= *state
;
1732 if (flag_exceptions
)
1734 gimple inner
= gimple_seq_first_stmt (gimple_try_cleanup (tp
));
1735 eh_region this_region
;
1737 this_region
= gen_eh_region_must_not_throw (state
->cur_region
);
1738 this_region
->u
.must_not_throw
.failure_decl
1739 = gimple_eh_must_not_throw_fndecl (inner
);
1740 this_region
->u
.must_not_throw
.failure_loc
= gimple_location (tp
);
1742 /* In order to get mangling applied to this decl, we must mark it
1743 used now. Otherwise, pass_ipa_free_lang_data won't think it
1745 TREE_USED (this_region
->u
.must_not_throw
.failure_decl
) = 1;
1747 this_state
.cur_region
= this_region
;
1750 lower_eh_constructs_1 (&this_state
, gimple_try_eval (tp
));
1752 return gimple_try_eval (tp
);
1755 /* Implement a cleanup expression. This is similar to try-finally,
1756 except that we only execute the cleanup block for exception edges. */
1759 lower_cleanup (struct leh_state
*state
, gimple tp
)
1761 struct leh_state this_state
= *state
;
1762 eh_region this_region
= NULL
;
1763 struct leh_tf_state fake_tf
;
1766 if (flag_exceptions
)
1768 this_region
= gen_eh_region_cleanup (state
->cur_region
);
1769 this_state
.cur_region
= this_region
;
1772 lower_eh_constructs_1 (&this_state
, gimple_try_eval (tp
));
1774 if (!eh_region_may_contain_throw (this_region
))
1775 return gimple_try_eval (tp
);
1777 /* Build enough of a try-finally state so that we can reuse
1778 honor_protect_cleanup_actions. */
1779 memset (&fake_tf
, 0, sizeof (fake_tf
));
1780 fake_tf
.top_p
= fake_tf
.try_finally_expr
= tp
;
1781 fake_tf
.outer
= state
;
1782 fake_tf
.region
= this_region
;
1783 fake_tf
.may_fallthru
= gimple_seq_may_fallthru (gimple_try_eval (tp
));
1784 fake_tf
.may_throw
= true;
1786 honor_protect_cleanup_actions (state
, NULL
, &fake_tf
);
1788 if (fake_tf
.may_throw
)
1790 /* In this case honor_protect_cleanup_actions had nothing to do,
1791 and we should process this normally. */
1792 lower_eh_constructs_1 (state
, gimple_try_cleanup (tp
));
1793 result
= frob_into_branch_around (tp
, this_region
,
1794 fake_tf
.fallthru_label
);
1798 /* In this case honor_protect_cleanup_actions did nearly all of
1799 the work. All we have left is to append the fallthru_label. */
1801 result
= gimple_try_eval (tp
);
1802 if (fake_tf
.fallthru_label
)
1804 gimple x
= gimple_build_label (fake_tf
.fallthru_label
);
1805 gimple_seq_add_stmt (&result
, x
);
1811 /* Main loop for lowering eh constructs. Also moves gsi to the next
1815 lower_eh_constructs_2 (struct leh_state
*state
, gimple_stmt_iterator
*gsi
)
1819 gimple stmt
= gsi_stmt (*gsi
);
1821 switch (gimple_code (stmt
))
1825 tree fndecl
= gimple_call_fndecl (stmt
);
1828 if (fndecl
&& DECL_BUILT_IN_CLASS (fndecl
) == BUILT_IN_NORMAL
)
1829 switch (DECL_FUNCTION_CODE (fndecl
))
1831 case BUILT_IN_EH_POINTER
:
1832 /* The front end may have generated a call to
1833 __builtin_eh_pointer (0) within a catch region. Replace
1834 this zero argument with the current catch region number. */
1835 if (state
->ehp_region
)
1837 tree nr
= build_int_cst (NULL
, state
->ehp_region
->index
);
1838 gimple_call_set_arg (stmt
, 0, nr
);
1842 /* The user has dome something silly. Remove it. */
1843 rhs
= build_int_cst (ptr_type_node
, 0);
1848 case BUILT_IN_EH_FILTER
:
1849 /* ??? This should never appear, but since it's a builtin it
1850 is accessible to abuse by users. Just remove it and
1851 replace the use with the arbitrary value zero. */
1852 rhs
= build_int_cst (TREE_TYPE (TREE_TYPE (fndecl
)), 0);
1854 lhs
= gimple_call_lhs (stmt
);
1855 x
= gimple_build_assign (lhs
, rhs
);
1856 gsi_insert_before (gsi
, x
, GSI_SAME_STMT
);
1859 case BUILT_IN_EH_COPY_VALUES
:
1860 /* Likewise this should not appear. Remove it. */
1861 gsi_remove (gsi
, true);
1871 /* If the stmt can throw use a new temporary for the assignment
1872 to a LHS. This makes sure the old value of the LHS is
1873 available on the EH edge. Only do so for statements that
1874 potentially fall thru (no noreturn calls e.g.), otherwise
1875 this new assignment might create fake fallthru regions. */
1876 if (stmt_could_throw_p (stmt
)
1877 && gimple_has_lhs (stmt
)
1878 && gimple_stmt_may_fallthru (stmt
)
1879 && !tree_could_throw_p (gimple_get_lhs (stmt
))
1880 && is_gimple_reg_type (TREE_TYPE (gimple_get_lhs (stmt
))))
1882 tree lhs
= gimple_get_lhs (stmt
);
1883 tree tmp
= create_tmp_var (TREE_TYPE (lhs
), NULL
);
1884 gimple s
= gimple_build_assign (lhs
, tmp
);
1885 gimple_set_location (s
, gimple_location (stmt
));
1886 gimple_set_block (s
, gimple_block (stmt
));
1887 gimple_set_lhs (stmt
, tmp
);
1888 if (TREE_CODE (TREE_TYPE (tmp
)) == COMPLEX_TYPE
1889 || TREE_CODE (TREE_TYPE (tmp
)) == VECTOR_TYPE
)
1890 DECL_GIMPLE_REG_P (tmp
) = 1;
1891 gsi_insert_after (gsi
, s
, GSI_SAME_STMT
);
1893 /* Look for things that can throw exceptions, and record them. */
1894 if (state
->cur_region
&& stmt_could_throw_p (stmt
))
1896 record_stmt_eh_region (state
->cur_region
, stmt
);
1897 note_eh_region_may_contain_throw (state
->cur_region
);
1904 maybe_record_in_goto_queue (state
, stmt
);
1908 verify_norecord_switch_expr (state
, stmt
);
1912 if (gimple_try_kind (stmt
) == GIMPLE_TRY_FINALLY
)
1913 replace
= lower_try_finally (state
, stmt
);
1916 x
= gimple_seq_first_stmt (gimple_try_cleanup (stmt
));
1919 replace
= gimple_try_eval (stmt
);
1920 lower_eh_constructs_1 (state
, replace
);
1923 switch (gimple_code (x
))
1926 replace
= lower_catch (state
, stmt
);
1928 case GIMPLE_EH_FILTER
:
1929 replace
= lower_eh_filter (state
, stmt
);
1931 case GIMPLE_EH_MUST_NOT_THROW
:
1932 replace
= lower_eh_must_not_throw (state
, stmt
);
1935 replace
= lower_cleanup (state
, stmt
);
1940 /* Remove the old stmt and insert the transformed sequence
1942 gsi_insert_seq_before (gsi
, replace
, GSI_SAME_STMT
);
1943 gsi_remove (gsi
, true);
1945 /* Return since we don't want gsi_next () */
1949 /* A type, a decl, or some kind of statement that we're not
1950 interested in. Don't walk them. */
1957 /* A helper to unwrap a gimple_seq and feed stmts to lower_eh_constructs_2. */
1960 lower_eh_constructs_1 (struct leh_state
*state
, gimple_seq seq
)
1962 gimple_stmt_iterator gsi
;
1963 for (gsi
= gsi_start (seq
); !gsi_end_p (gsi
);)
1964 lower_eh_constructs_2 (state
, &gsi
);
1968 lower_eh_constructs (void)
1970 struct leh_state null_state
;
1973 bodyp
= gimple_body (current_function_decl
);
1977 finally_tree
= htab_create (31, struct_ptr_hash
, struct_ptr_eq
, free
);
1978 eh_region_may_contain_throw_map
= BITMAP_ALLOC (NULL
);
1979 memset (&null_state
, 0, sizeof (null_state
));
1981 collect_finally_tree_1 (bodyp
, NULL
);
1982 lower_eh_constructs_1 (&null_state
, bodyp
);
1984 /* We assume there's a return statement, or something, at the end of
1985 the function, and thus ploping the EH sequence afterward won't
1987 gcc_assert (!gimple_seq_may_fallthru (bodyp
));
1988 gimple_seq_add_seq (&bodyp
, eh_seq
);
1990 /* We assume that since BODYP already existed, adding EH_SEQ to it
1991 didn't change its value, and we don't have to re-set the function. */
1992 gcc_assert (bodyp
== gimple_body (current_function_decl
));
1994 htab_delete (finally_tree
);
1995 BITMAP_FREE (eh_region_may_contain_throw_map
);
1998 /* If this function needs a language specific EH personality routine
1999 and the frontend didn't already set one do so now. */
2000 if (function_needs_eh_personality (cfun
) == eh_personality_lang
2001 && !DECL_FUNCTION_PERSONALITY (current_function_decl
))
2002 DECL_FUNCTION_PERSONALITY (current_function_decl
)
2003 = lang_hooks
.eh_personality ();
2008 struct gimple_opt_pass pass_lower_eh
=
2014 lower_eh_constructs
, /* execute */
2017 0, /* static_pass_number */
2018 TV_TREE_EH
, /* tv_id */
2019 PROP_gimple_lcf
, /* properties_required */
2020 PROP_gimple_leh
, /* properties_provided */
2021 0, /* properties_destroyed */
2022 0, /* todo_flags_start */
2023 TODO_dump_func
/* todo_flags_finish */
2027 /* Create the multiple edges from an EH_DISPATCH statement to all of
2028 the possible handlers for its EH region. Return true if there's
2029 no fallthru edge; false if there is. */
2032 make_eh_dispatch_edges (gimple stmt
)
2036 basic_block src
, dst
;
2038 r
= get_eh_region_from_number (gimple_eh_dispatch_region (stmt
));
2039 src
= gimple_bb (stmt
);
2044 for (c
= r
->u
.eh_try
.first_catch
; c
; c
= c
->next_catch
)
2046 dst
= label_to_block (c
->label
);
2047 make_edge (src
, dst
, 0);
2049 /* A catch-all handler doesn't have a fallthru. */
2050 if (c
->type_list
== NULL
)
2055 case ERT_ALLOWED_EXCEPTIONS
:
2056 dst
= label_to_block (r
->u
.allowed
.label
);
2057 make_edge (src
, dst
, 0);
2067 /* Create the single EH edge from STMT to its nearest landing pad,
2068 if there is such a landing pad within the current function. */
2071 make_eh_edges (gimple stmt
)
2073 basic_block src
, dst
;
2077 lp_nr
= lookup_stmt_eh_lp (stmt
);
2081 lp
= get_eh_landing_pad_from_number (lp_nr
);
2082 gcc_assert (lp
!= NULL
);
2084 src
= gimple_bb (stmt
);
2085 dst
= label_to_block (lp
->post_landing_pad
);
2086 make_edge (src
, dst
, EDGE_EH
);
2089 /* Do the work in redirecting EDGE_IN to NEW_BB within the EH region tree;
2090 do not actually perform the final edge redirection.
2092 CHANGE_REGION is true when we're being called from cleanup_empty_eh and
2093 we intend to change the destination EH region as well; this means
2094 EH_LANDING_PAD_NR must already be set on the destination block label.
2095 If false, we're being called from generic cfg manipulation code and we
2096 should preserve our place within the region tree. */
2099 redirect_eh_edge_1 (edge edge_in
, basic_block new_bb
, bool change_region
)
2101 eh_landing_pad old_lp
, new_lp
;
2104 int old_lp_nr
, new_lp_nr
;
2105 tree old_label
, new_label
;
2109 old_bb
= edge_in
->dest
;
2110 old_label
= gimple_block_label (old_bb
);
2111 old_lp_nr
= EH_LANDING_PAD_NR (old_label
);
2112 gcc_assert (old_lp_nr
> 0);
2113 old_lp
= get_eh_landing_pad_from_number (old_lp_nr
);
2115 throw_stmt
= last_stmt (edge_in
->src
);
2116 gcc_assert (lookup_stmt_eh_lp (throw_stmt
) == old_lp_nr
);
2118 new_label
= gimple_block_label (new_bb
);
2120 /* Look for an existing region that might be using NEW_BB already. */
2121 new_lp_nr
= EH_LANDING_PAD_NR (new_label
);
2124 new_lp
= get_eh_landing_pad_from_number (new_lp_nr
);
2125 gcc_assert (new_lp
);
2127 /* Unless CHANGE_REGION is true, the new and old landing pad
2128 had better be associated with the same EH region. */
2129 gcc_assert (change_region
|| new_lp
->region
== old_lp
->region
);
2134 gcc_assert (!change_region
);
2137 /* Notice when we redirect the last EH edge away from OLD_BB. */
2138 FOR_EACH_EDGE (e
, ei
, old_bb
->preds
)
2139 if (e
!= edge_in
&& (e
->flags
& EDGE_EH
))
2144 /* NEW_LP already exists. If there are still edges into OLD_LP,
2145 there's nothing to do with the EH tree. If there are no more
2146 edges into OLD_LP, then we want to remove OLD_LP as it is unused.
2147 If CHANGE_REGION is true, then our caller is expecting to remove
2149 if (e
== NULL
&& !change_region
)
2150 remove_eh_landing_pad (old_lp
);
2154 /* No correct landing pad exists. If there are no more edges
2155 into OLD_LP, then we can simply re-use the existing landing pad.
2156 Otherwise, we have to create a new landing pad. */
2159 EH_LANDING_PAD_NR (old_lp
->post_landing_pad
) = 0;
2163 new_lp
= gen_eh_landing_pad (old_lp
->region
);
2164 new_lp
->post_landing_pad
= new_label
;
2165 EH_LANDING_PAD_NR (new_label
) = new_lp
->index
;
2168 /* Maybe move the throwing statement to the new region. */
2169 if (old_lp
!= new_lp
)
2171 remove_stmt_from_eh_lp (throw_stmt
);
2172 add_stmt_to_eh_lp (throw_stmt
, new_lp
->index
);
2176 /* Redirect EH edge E to NEW_BB. */
2179 redirect_eh_edge (edge edge_in
, basic_block new_bb
)
2181 redirect_eh_edge_1 (edge_in
, new_bb
, false);
2182 return ssa_redirect_edge (edge_in
, new_bb
);
2185 /* This is a subroutine of gimple_redirect_edge_and_branch. Update the
2186 labels for redirecting a non-fallthru EH_DISPATCH edge E to NEW_BB.
2187 The actual edge update will happen in the caller. */
2190 redirect_eh_dispatch_edge (gimple stmt
, edge e
, basic_block new_bb
)
2192 tree new_lab
= gimple_block_label (new_bb
);
2193 bool any_changed
= false;
2198 r
= get_eh_region_from_number (gimple_eh_dispatch_region (stmt
));
2202 for (c
= r
->u
.eh_try
.first_catch
; c
; c
= c
->next_catch
)
2204 old_bb
= label_to_block (c
->label
);
2205 if (old_bb
== e
->dest
)
2213 case ERT_ALLOWED_EXCEPTIONS
:
2214 old_bb
= label_to_block (r
->u
.allowed
.label
);
2215 gcc_assert (old_bb
== e
->dest
);
2216 r
->u
.allowed
.label
= new_lab
;
2224 gcc_assert (any_changed
);
2227 /* Helper function for operation_could_trap_p and stmt_could_throw_p. */
2230 operation_could_trap_helper_p (enum tree_code op
,
2241 case TRUNC_DIV_EXPR
:
2243 case FLOOR_DIV_EXPR
:
2244 case ROUND_DIV_EXPR
:
2245 case EXACT_DIV_EXPR
:
2247 case FLOOR_MOD_EXPR
:
2248 case ROUND_MOD_EXPR
:
2249 case TRUNC_MOD_EXPR
:
2251 if (honor_snans
|| honor_trapv
)
2254 return flag_trapping_math
;
2255 if (!TREE_CONSTANT (divisor
) || integer_zerop (divisor
))
2264 /* Some floating point comparisons may trap. */
2269 case UNORDERED_EXPR
:
2279 case FIX_TRUNC_EXPR
:
2280 /* Conversion of floating point might trap. */
2286 /* These operations don't trap with floating point. */
2294 /* Any floating arithmetic may trap. */
2295 if (fp_operation
&& flag_trapping_math
)
2302 /* Any floating arithmetic may trap. */
2303 if (fp_operation
&& flag_trapping_math
)
2311 /* Return true if operation OP may trap. FP_OPERATION is true if OP is applied
2312 on floating-point values. HONOR_TRAPV is true if OP is applied on integer
2313 type operands that may trap. If OP is a division operator, DIVISOR contains
2314 the value of the divisor. */
2317 operation_could_trap_p (enum tree_code op
, bool fp_operation
, bool honor_trapv
,
2320 bool honor_nans
= (fp_operation
&& flag_trapping_math
2321 && !flag_finite_math_only
);
2322 bool honor_snans
= fp_operation
&& flag_signaling_nans
!= 0;
2325 if (TREE_CODE_CLASS (op
) != tcc_comparison
2326 && TREE_CODE_CLASS (op
) != tcc_unary
2327 && TREE_CODE_CLASS (op
) != tcc_binary
)
2330 return operation_could_trap_helper_p (op
, fp_operation
, honor_trapv
,
2331 honor_nans
, honor_snans
, divisor
,
2335 /* Return true if EXPR can trap, as in dereferencing an invalid pointer
2336 location or floating point arithmetic. C.f. the rtl version, may_trap_p.
2337 This routine expects only GIMPLE lhs or rhs input. */
2340 tree_could_trap_p (tree expr
)
2342 enum tree_code code
;
2343 bool fp_operation
= false;
2344 bool honor_trapv
= false;
2345 tree t
, base
, div
= NULL_TREE
;
2350 code
= TREE_CODE (expr
);
2351 t
= TREE_TYPE (expr
);
2355 if (COMPARISON_CLASS_P (expr
))
2356 fp_operation
= FLOAT_TYPE_P (TREE_TYPE (TREE_OPERAND (expr
, 0)));
2358 fp_operation
= FLOAT_TYPE_P (t
);
2359 honor_trapv
= INTEGRAL_TYPE_P (t
) && TYPE_OVERFLOW_TRAPS (t
);
2362 if (TREE_CODE_CLASS (code
) == tcc_binary
)
2363 div
= TREE_OPERAND (expr
, 1);
2364 if (operation_could_trap_p (code
, fp_operation
, honor_trapv
, div
))
2370 case TARGET_MEM_REF
:
2371 /* For TARGET_MEM_REFs use the information based on the original
2373 expr
= TMR_ORIGINAL (expr
);
2374 code
= TREE_CODE (expr
);
2381 case VIEW_CONVERT_EXPR
:
2382 case WITH_SIZE_EXPR
:
2383 expr
= TREE_OPERAND (expr
, 0);
2384 code
= TREE_CODE (expr
);
2387 case ARRAY_RANGE_REF
:
2388 base
= TREE_OPERAND (expr
, 0);
2389 if (tree_could_trap_p (base
))
2391 if (TREE_THIS_NOTRAP (expr
))
2393 return !range_in_array_bounds_p (expr
);
2396 base
= TREE_OPERAND (expr
, 0);
2397 if (tree_could_trap_p (base
))
2399 if (TREE_THIS_NOTRAP (expr
))
2401 return !in_array_bounds_p (expr
);
2404 case ALIGN_INDIRECT_REF
:
2405 case MISALIGNED_INDIRECT_REF
:
2406 return !TREE_THIS_NOTRAP (expr
);
2409 return TREE_THIS_VOLATILE (expr
);
2412 t
= get_callee_fndecl (expr
);
2413 /* Assume that calls to weak functions may trap. */
2414 if (!t
|| !DECL_P (t
) || DECL_WEAK (t
))
2424 /* Helper for stmt_could_throw_p. Return true if STMT (assumed to be a
2425 an assignment or a conditional) may throw. */
2428 stmt_could_throw_1_p (gimple stmt
)
2430 enum tree_code code
= gimple_expr_code (stmt
);
2431 bool honor_nans
= false;
2432 bool honor_snans
= false;
2433 bool fp_operation
= false;
2434 bool honor_trapv
= false;
2439 if (TREE_CODE_CLASS (code
) == tcc_comparison
2440 || TREE_CODE_CLASS (code
) == tcc_unary
2441 || TREE_CODE_CLASS (code
) == tcc_binary
)
2443 t
= gimple_expr_type (stmt
);
2444 fp_operation
= FLOAT_TYPE_P (t
);
2447 honor_nans
= flag_trapping_math
&& !flag_finite_math_only
;
2448 honor_snans
= flag_signaling_nans
!= 0;
2450 else if (INTEGRAL_TYPE_P (t
) && TYPE_OVERFLOW_TRAPS (t
))
2454 /* Check if the main expression may trap. */
2455 t
= is_gimple_assign (stmt
) ? gimple_assign_rhs2 (stmt
) : NULL
;
2456 ret
= operation_could_trap_helper_p (code
, fp_operation
, honor_trapv
,
2457 honor_nans
, honor_snans
, t
,
2462 /* If the expression does not trap, see if any of the individual operands may
2464 for (i
= 0; i
< gimple_num_ops (stmt
); i
++)
2465 if (tree_could_trap_p (gimple_op (stmt
, i
)))
2472 /* Return true if statement STMT could throw an exception. */
2475 stmt_could_throw_p (gimple stmt
)
2477 if (!flag_exceptions
)
2480 /* The only statements that can throw an exception are assignments,
2481 conditionals, calls, resx, and asms. */
2482 switch (gimple_code (stmt
))
2488 return !gimple_call_nothrow_p (stmt
);
2492 if (!flag_non_call_exceptions
)
2494 return stmt_could_throw_1_p (stmt
);
2497 if (!flag_non_call_exceptions
)
2499 return gimple_asm_volatile_p (stmt
);
2507 /* Return true if expression T could throw an exception. */
2510 tree_could_throw_p (tree t
)
2512 if (!flag_exceptions
)
2514 if (TREE_CODE (t
) == MODIFY_EXPR
)
2516 if (flag_non_call_exceptions
2517 && tree_could_trap_p (TREE_OPERAND (t
, 0)))
2519 t
= TREE_OPERAND (t
, 1);
2522 if (TREE_CODE (t
) == WITH_SIZE_EXPR
)
2523 t
= TREE_OPERAND (t
, 0);
2524 if (TREE_CODE (t
) == CALL_EXPR
)
2525 return (call_expr_flags (t
) & ECF_NOTHROW
) == 0;
2526 if (flag_non_call_exceptions
)
2527 return tree_could_trap_p (t
);
2531 /* Return true if STMT can throw an exception that is not caught within
2532 the current function (CFUN). */
2535 stmt_can_throw_external (gimple stmt
)
2539 if (!stmt_could_throw_p (stmt
))
2542 lp_nr
= lookup_stmt_eh_lp (stmt
);
2546 /* Return true if STMT can throw an exception that is caught within
2547 the current function (CFUN). */
2550 stmt_can_throw_internal (gimple stmt
)
2554 if (!stmt_could_throw_p (stmt
))
2557 lp_nr
= lookup_stmt_eh_lp (stmt
);
2561 /* Given a statement STMT in IFUN, if STMT can no longer throw, then
2562 remove any entry it might have from the EH table. Return true if
2563 any change was made. */
2566 maybe_clean_eh_stmt_fn (struct function
*ifun
, gimple stmt
)
2568 if (stmt_could_throw_p (stmt
))
2570 return remove_stmt_from_eh_lp_fn (ifun
, stmt
);
2573 /* Likewise, but always use the current function. */
2576 maybe_clean_eh_stmt (gimple stmt
)
2578 return maybe_clean_eh_stmt_fn (cfun
, stmt
);
2581 /* Given a statement OLD_STMT and a new statement NEW_STMT that has replaced
2582 OLD_STMT in the function, remove OLD_STMT from the EH table and put NEW_STMT
2583 in the table if it should be in there. Return TRUE if a replacement was
2584 done that my require an EH edge purge. */
2587 maybe_clean_or_replace_eh_stmt (gimple old_stmt
, gimple new_stmt
)
2589 int lp_nr
= lookup_stmt_eh_lp (old_stmt
);
2593 bool new_stmt_could_throw
= stmt_could_throw_p (new_stmt
);
2595 if (new_stmt
== old_stmt
&& new_stmt_could_throw
)
2598 remove_stmt_from_eh_lp (old_stmt
);
2599 if (new_stmt_could_throw
)
2601 add_stmt_to_eh_lp (new_stmt
, lp_nr
);
2611 /* Given a statement OLD_STMT in OLD_FUN and a duplicate statment NEW_STMT
2612 in NEW_FUN, copy the EH table data from OLD_STMT to NEW_STMT. The MAP
2613 operand is the return value of duplicate_eh_regions. */
2616 maybe_duplicate_eh_stmt_fn (struct function
*new_fun
, gimple new_stmt
,
2617 struct function
*old_fun
, gimple old_stmt
,
2618 struct pointer_map_t
*map
, int default_lp_nr
)
2620 int old_lp_nr
, new_lp_nr
;
2623 if (!stmt_could_throw_p (new_stmt
))
2626 old_lp_nr
= lookup_stmt_eh_lp_fn (old_fun
, old_stmt
);
2629 if (default_lp_nr
== 0)
2631 new_lp_nr
= default_lp_nr
;
2633 else if (old_lp_nr
> 0)
2635 eh_landing_pad old_lp
, new_lp
;
2637 old_lp
= VEC_index (eh_landing_pad
, old_fun
->eh
->lp_array
, old_lp_nr
);
2638 slot
= pointer_map_contains (map
, old_lp
);
2639 new_lp
= (eh_landing_pad
) *slot
;
2640 new_lp_nr
= new_lp
->index
;
2644 eh_region old_r
, new_r
;
2646 old_r
= VEC_index (eh_region
, old_fun
->eh
->region_array
, -old_lp_nr
);
2647 slot
= pointer_map_contains (map
, old_r
);
2648 new_r
= (eh_region
) *slot
;
2649 new_lp_nr
= -new_r
->index
;
2652 add_stmt_to_eh_lp_fn (new_fun
, new_stmt
, new_lp_nr
);
2656 /* Similar, but both OLD_STMT and NEW_STMT are within the current function,
2657 and thus no remapping is required. */
2660 maybe_duplicate_eh_stmt (gimple new_stmt
, gimple old_stmt
)
2664 if (!stmt_could_throw_p (new_stmt
))
2667 lp_nr
= lookup_stmt_eh_lp (old_stmt
);
2671 add_stmt_to_eh_lp (new_stmt
, lp_nr
);
2675 /* Returns TRUE if oneh and twoh are exception handlers (gimple_try_cleanup of
2676 GIMPLE_TRY) that are similar enough to be considered the same. Currently
2677 this only handles handlers consisting of a single call, as that's the
2678 important case for C++: a destructor call for a particular object showing
2679 up in multiple handlers. */
2682 same_handler_p (gimple_seq oneh
, gimple_seq twoh
)
2684 gimple_stmt_iterator gsi
;
2688 gsi
= gsi_start (oneh
);
2689 if (!gsi_one_before_end_p (gsi
))
2691 ones
= gsi_stmt (gsi
);
2693 gsi
= gsi_start (twoh
);
2694 if (!gsi_one_before_end_p (gsi
))
2696 twos
= gsi_stmt (gsi
);
2698 if (!is_gimple_call (ones
)
2699 || !is_gimple_call (twos
)
2700 || gimple_call_lhs (ones
)
2701 || gimple_call_lhs (twos
)
2702 || gimple_call_chain (ones
)
2703 || gimple_call_chain (twos
)
2704 || !operand_equal_p (gimple_call_fn (ones
), gimple_call_fn (twos
), 0)
2705 || gimple_call_num_args (ones
) != gimple_call_num_args (twos
))
2708 for (ai
= 0; ai
< gimple_call_num_args (ones
); ++ai
)
2709 if (!operand_equal_p (gimple_call_arg (ones
, ai
),
2710 gimple_call_arg (twos
, ai
), 0))
2717 try { A() } finally { try { ~B() } catch { ~A() } }
2718 try { ... } finally { ~A() }
2720 try { A() } catch { ~B() }
2721 try { ~B() ... } finally { ~A() }
2723 This occurs frequently in C++, where A is a local variable and B is a
2724 temporary used in the initializer for A. */
2727 optimize_double_finally (gimple one
, gimple two
)
2730 gimple_stmt_iterator gsi
;
2732 gsi
= gsi_start (gimple_try_cleanup (one
));
2733 if (!gsi_one_before_end_p (gsi
))
2736 oneh
= gsi_stmt (gsi
);
2737 if (gimple_code (oneh
) != GIMPLE_TRY
2738 || gimple_try_kind (oneh
) != GIMPLE_TRY_CATCH
)
2741 if (same_handler_p (gimple_try_cleanup (oneh
), gimple_try_cleanup (two
)))
2743 gimple_seq seq
= gimple_try_eval (oneh
);
2745 gimple_try_set_cleanup (one
, seq
);
2746 gimple_try_set_kind (one
, GIMPLE_TRY_CATCH
);
2747 seq
= copy_gimple_seq_and_replace_locals (seq
);
2748 gimple_seq_add_seq (&seq
, gimple_try_eval (two
));
2749 gimple_try_set_eval (two
, seq
);
2753 /* Perform EH refactoring optimizations that are simpler to do when code
2754 flow has been lowered but EH structures haven't. */
2757 refactor_eh_r (gimple_seq seq
)
2759 gimple_stmt_iterator gsi
;
2764 gsi
= gsi_start (seq
);
2768 if (gsi_end_p (gsi
))
2771 two
= gsi_stmt (gsi
);
2774 && gimple_code (one
) == GIMPLE_TRY
2775 && gimple_code (two
) == GIMPLE_TRY
2776 && gimple_try_kind (one
) == GIMPLE_TRY_FINALLY
2777 && gimple_try_kind (two
) == GIMPLE_TRY_FINALLY
)
2778 optimize_double_finally (one
, two
);
2780 switch (gimple_code (one
))
2783 refactor_eh_r (gimple_try_eval (one
));
2784 refactor_eh_r (gimple_try_cleanup (one
));
2787 refactor_eh_r (gimple_catch_handler (one
));
2789 case GIMPLE_EH_FILTER
:
2790 refactor_eh_r (gimple_eh_filter_failure (one
));
2805 refactor_eh_r (gimple_body (current_function_decl
));
2810 gate_refactor_eh (void)
2812 return flag_exceptions
!= 0;
2815 struct gimple_opt_pass pass_refactor_eh
=
2820 gate_refactor_eh
, /* gate */
2821 refactor_eh
, /* execute */
2824 0, /* static_pass_number */
2825 TV_TREE_EH
, /* tv_id */
2826 PROP_gimple_lcf
, /* properties_required */
2827 0, /* properties_provided */
2828 0, /* properties_destroyed */
2829 0, /* todo_flags_start */
2830 TODO_dump_func
/* todo_flags_finish */
2834 /* At the end of gimple optimization, we can lower RESX. */
2837 lower_resx (basic_block bb
, gimple stmt
, struct pointer_map_t
*mnt_map
)
2840 eh_region src_r
, dst_r
;
2841 gimple_stmt_iterator gsi
;
2846 lp_nr
= lookup_stmt_eh_lp (stmt
);
2848 dst_r
= get_eh_region_from_lp_number (lp_nr
);
2852 src_r
= get_eh_region_from_number (gimple_resx_region (stmt
));
2853 gsi
= gsi_last_bb (bb
);
2857 /* We can wind up with no source region when pass_cleanup_eh shows
2858 that there are no entries into an eh region and deletes it, but
2859 then the block that contains the resx isn't removed. This can
2860 happen without optimization when the switch statement created by
2861 lower_try_finally_switch isn't simplified to remove the eh case.
2863 Resolve this by expanding the resx node to an abort. */
2865 fn
= implicit_built_in_decls
[BUILT_IN_TRAP
];
2866 x
= gimple_build_call (fn
, 0);
2867 gsi_insert_before (&gsi
, x
, GSI_SAME_STMT
);
2869 while (EDGE_COUNT (bb
->succs
) > 0)
2870 remove_edge (EDGE_SUCC (bb
, 0));
2874 /* When we have a destination region, we resolve this by copying
2875 the excptr and filter values into place, and changing the edge
2876 to immediately after the landing pad. */
2885 /* We are resuming into a MUST_NOT_CALL region. Expand a call to
2886 the failure decl into a new block, if needed. */
2887 gcc_assert (dst_r
->type
== ERT_MUST_NOT_THROW
);
2889 slot
= pointer_map_contains (mnt_map
, dst_r
);
2892 gimple_stmt_iterator gsi2
;
2894 new_bb
= create_empty_bb (bb
);
2895 lab
= gimple_block_label (new_bb
);
2896 gsi2
= gsi_start_bb (new_bb
);
2898 fn
= dst_r
->u
.must_not_throw
.failure_decl
;
2899 x
= gimple_build_call (fn
, 0);
2900 gimple_set_location (x
, dst_r
->u
.must_not_throw
.failure_loc
);
2901 gsi_insert_after (&gsi2
, x
, GSI_CONTINUE_LINKING
);
2903 slot
= pointer_map_insert (mnt_map
, dst_r
);
2909 new_bb
= label_to_block (lab
);
2912 gcc_assert (EDGE_COUNT (bb
->succs
) == 0);
2913 e
= make_edge (bb
, new_bb
, EDGE_FALLTHRU
);
2914 e
->count
= bb
->count
;
2915 e
->probability
= REG_BR_PROB_BASE
;
2920 tree dst_nr
= build_int_cst (NULL
, dst_r
->index
);
2922 fn
= implicit_built_in_decls
[BUILT_IN_EH_COPY_VALUES
];
2923 src_nr
= build_int_cst (NULL
, src_r
->index
);
2924 x
= gimple_build_call (fn
, 2, dst_nr
, src_nr
);
2925 gsi_insert_before (&gsi
, x
, GSI_SAME_STMT
);
2927 /* Update the flags for the outgoing edge. */
2928 e
= single_succ_edge (bb
);
2929 gcc_assert (e
->flags
& EDGE_EH
);
2930 e
->flags
= (e
->flags
& ~EDGE_EH
) | EDGE_FALLTHRU
;
2932 /* If there are no more EH users of the landing pad, delete it. */
2933 FOR_EACH_EDGE (e
, ei
, e
->dest
->preds
)
2934 if (e
->flags
& EDGE_EH
)
2938 eh_landing_pad lp
= get_eh_landing_pad_from_number (lp_nr
);
2939 remove_eh_landing_pad (lp
);
2949 /* When we don't have a destination region, this exception escapes
2950 up the call chain. We resolve this by generating a call to the
2951 _Unwind_Resume library function. */
2953 /* The ARM EABI redefines _Unwind_Resume as __cxa_end_cleanup
2954 with no arguments for C++ and Java. Check for that. */
2955 if (src_r
->use_cxa_end_cleanup
)
2957 fn
= implicit_built_in_decls
[BUILT_IN_CXA_END_CLEANUP
];
2958 x
= gimple_build_call (fn
, 0);
2959 gsi_insert_before (&gsi
, x
, GSI_SAME_STMT
);
2963 fn
= implicit_built_in_decls
[BUILT_IN_EH_POINTER
];
2964 src_nr
= build_int_cst (NULL
, src_r
->index
);
2965 x
= gimple_build_call (fn
, 1, src_nr
);
2966 var
= create_tmp_var (ptr_type_node
, NULL
);
2967 var
= make_ssa_name (var
, x
);
2968 gimple_call_set_lhs (x
, var
);
2969 gsi_insert_before (&gsi
, x
, GSI_SAME_STMT
);
2971 fn
= implicit_built_in_decls
[BUILT_IN_UNWIND_RESUME
];
2972 x
= gimple_build_call (fn
, 1, var
);
2973 gsi_insert_before (&gsi
, x
, GSI_SAME_STMT
);
2976 gcc_assert (EDGE_COUNT (bb
->succs
) == 0);
2979 gsi_remove (&gsi
, true);
2985 execute_lower_resx (void)
2988 struct pointer_map_t
*mnt_map
;
2989 bool dominance_invalidated
= false;
2990 bool any_rewritten
= false;
2992 mnt_map
= pointer_map_create ();
2996 gimple last
= last_stmt (bb
);
2997 if (last
&& is_gimple_resx (last
))
2999 dominance_invalidated
|= lower_resx (bb
, last
, mnt_map
);
3000 any_rewritten
= true;
3004 pointer_map_destroy (mnt_map
);
3006 if (dominance_invalidated
)
3008 free_dominance_info (CDI_DOMINATORS
);
3009 free_dominance_info (CDI_POST_DOMINATORS
);
3012 return any_rewritten
? TODO_update_ssa_only_virtuals
: 0;
3016 gate_lower_resx (void)
3018 return flag_exceptions
!= 0;
3021 struct gimple_opt_pass pass_lower_resx
=
3026 gate_lower_resx
, /* gate */
3027 execute_lower_resx
, /* execute */
3030 0, /* static_pass_number */
3031 TV_TREE_EH
, /* tv_id */
3032 PROP_gimple_lcf
, /* properties_required */
3033 0, /* properties_provided */
3034 0, /* properties_destroyed */
3035 0, /* todo_flags_start */
3036 TODO_dump_func
| TODO_verify_flow
/* todo_flags_finish */
3041 /* At the end of inlining, we can lower EH_DISPATCH. */
3044 lower_eh_dispatch (basic_block src
, gimple stmt
)
3046 gimple_stmt_iterator gsi
;
3052 region_nr
= gimple_eh_dispatch_region (stmt
);
3053 r
= get_eh_region_from_number (region_nr
);
3055 gsi
= gsi_last_bb (src
);
3061 VEC (tree
, heap
) *labels
= NULL
;
3062 tree default_label
= NULL
;
3067 /* Collect the labels for a switch. Zero the post_landing_pad
3068 field becase we'll no longer have anything keeping these labels
3069 in existance and the optimizer will be free to merge these
3071 for (c
= r
->u
.eh_try
.first_catch
; c
; c
= c
->next_catch
)
3073 tree tp_node
, flt_node
, lab
= c
->label
;
3076 tp_node
= c
->type_list
;
3077 flt_node
= c
->filter_list
;
3079 if (tp_node
== NULL
)
3081 default_label
= lab
;
3086 tree t
= build3 (CASE_LABEL_EXPR
, void_type_node
,
3087 TREE_VALUE (flt_node
), NULL
, lab
);
3088 VEC_safe_push (tree
, heap
, labels
, t
);
3090 tp_node
= TREE_CHAIN (tp_node
);
3091 flt_node
= TREE_CHAIN (flt_node
);
3096 /* Clean up the edge flags. */
3097 FOR_EACH_EDGE (e
, ei
, src
->succs
)
3099 if (e
->flags
& EDGE_FALLTHRU
)
3101 /* If there was no catch-all, use the fallthru edge. */
3102 if (default_label
== NULL
)
3103 default_label
= gimple_block_label (e
->dest
);
3104 e
->flags
&= ~EDGE_FALLTHRU
;
3107 gcc_assert (default_label
!= NULL
);
3109 /* Don't generate a switch if there's only a default case.
3110 This is common in the form of try { A; } catch (...) { B; }. */
3113 e
= single_succ_edge (src
);
3114 e
->flags
|= EDGE_FALLTHRU
;
3118 fn
= implicit_built_in_decls
[BUILT_IN_EH_FILTER
];
3119 x
= gimple_build_call (fn
, 1, build_int_cst (NULL
, region_nr
));
3120 filter
= create_tmp_var (TREE_TYPE (TREE_TYPE (fn
)), NULL
);
3121 filter
= make_ssa_name (filter
, x
);
3122 gimple_call_set_lhs (x
, filter
);
3123 gsi_insert_before (&gsi
, x
, GSI_SAME_STMT
);
3125 /* Turn the default label into a default case. */
3126 default_label
= build3 (CASE_LABEL_EXPR
, void_type_node
,
3127 NULL
, NULL
, default_label
);
3128 sort_case_labels (labels
);
3130 x
= gimple_build_switch_vec (filter
, default_label
, labels
);
3131 gsi_insert_before (&gsi
, x
, GSI_SAME_STMT
);
3133 VEC_free (tree
, heap
, labels
);
3138 case ERT_ALLOWED_EXCEPTIONS
:
3140 edge b_e
= BRANCH_EDGE (src
);
3141 edge f_e
= FALLTHRU_EDGE (src
);
3143 fn
= implicit_built_in_decls
[BUILT_IN_EH_FILTER
];
3144 x
= gimple_build_call (fn
, 1, build_int_cst (NULL
, region_nr
));
3145 filter
= create_tmp_var (TREE_TYPE (TREE_TYPE (fn
)), NULL
);
3146 filter
= make_ssa_name (filter
, x
);
3147 gimple_call_set_lhs (x
, filter
);
3148 gsi_insert_before (&gsi
, x
, GSI_SAME_STMT
);
3150 r
->u
.allowed
.label
= NULL
;
3151 x
= gimple_build_cond (EQ_EXPR
, filter
,
3152 build_int_cst (TREE_TYPE (filter
),
3153 r
->u
.allowed
.filter
),
3154 NULL_TREE
, NULL_TREE
);
3155 gsi_insert_before (&gsi
, x
, GSI_SAME_STMT
);
3157 b_e
->flags
= b_e
->flags
| EDGE_TRUE_VALUE
;
3158 f_e
->flags
= (f_e
->flags
& ~EDGE_FALLTHRU
) | EDGE_FALSE_VALUE
;
3166 /* Replace the EH_DISPATCH with the SWITCH or COND generated above. */
3167 gsi_remove (&gsi
, true);
3171 execute_lower_eh_dispatch (void)
3174 bool any_rewritten
= false;
3176 assign_filter_values ();
3180 gimple last
= last_stmt (bb
);
3181 if (last
&& gimple_code (last
) == GIMPLE_EH_DISPATCH
)
3183 lower_eh_dispatch (bb
, last
);
3184 any_rewritten
= true;
3188 return any_rewritten
? TODO_update_ssa_only_virtuals
: 0;
3192 gate_lower_eh_dispatch (void)
3194 return cfun
->eh
->region_tree
!= NULL
;
3197 struct gimple_opt_pass pass_lower_eh_dispatch
=
3201 "ehdisp", /* name */
3202 gate_lower_eh_dispatch
, /* gate */
3203 execute_lower_eh_dispatch
, /* execute */
3206 0, /* static_pass_number */
3207 TV_TREE_EH
, /* tv_id */
3208 PROP_gimple_lcf
, /* properties_required */
3209 0, /* properties_provided */
3210 0, /* properties_destroyed */
3211 0, /* todo_flags_start */
3212 TODO_dump_func
| TODO_verify_flow
/* todo_flags_finish */
3216 /* Walk statements, see what regions are really referenced and remove
3217 those that are unused. */
3220 remove_unreachable_handlers (void)
3222 sbitmap r_reachable
, lp_reachable
;
3228 r_reachable
= sbitmap_alloc (VEC_length (eh_region
, cfun
->eh
->region_array
));
3230 = sbitmap_alloc (VEC_length (eh_landing_pad
, cfun
->eh
->lp_array
));
3231 sbitmap_zero (r_reachable
);
3232 sbitmap_zero (lp_reachable
);
3236 gimple_stmt_iterator gsi
= gsi_start_bb (bb
);
3238 for (gsi
= gsi_start_bb (bb
); !gsi_end_p (gsi
); gsi_next (&gsi
))
3240 gimple stmt
= gsi_stmt (gsi
);
3241 lp_nr
= lookup_stmt_eh_lp (stmt
);
3243 /* Negative LP numbers are MUST_NOT_THROW regions which
3244 are not considered BB enders. */
3246 SET_BIT (r_reachable
, -lp_nr
);
3248 /* Positive LP numbers are real landing pads, are are BB enders. */
3251 gcc_assert (gsi_one_before_end_p (gsi
));
3252 region
= get_eh_region_from_lp_number (lp_nr
);
3253 SET_BIT (r_reachable
, region
->index
);
3254 SET_BIT (lp_reachable
, lp_nr
);
3261 fprintf (dump_file
, "Before removal of unreachable regions:\n");
3262 dump_eh_tree (dump_file
, cfun
);
3263 fprintf (dump_file
, "Reachable regions: ");
3264 dump_sbitmap_file (dump_file
, r_reachable
);
3265 fprintf (dump_file
, "Reachable landing pads: ");
3266 dump_sbitmap_file (dump_file
, lp_reachable
);
3270 VEC_iterate (eh_region
, cfun
->eh
->region_array
, r_nr
, region
); ++r_nr
)
3271 if (region
&& !TEST_BIT (r_reachable
, r_nr
))
3274 fprintf (dump_file
, "Removing unreachable region %d\n", r_nr
);
3275 remove_eh_handler (region
);
3279 VEC_iterate (eh_landing_pad
, cfun
->eh
->lp_array
, lp_nr
, lp
); ++lp_nr
)
3280 if (lp
&& !TEST_BIT (lp_reachable
, lp_nr
))
3283 fprintf (dump_file
, "Removing unreachable landing pad %d\n", lp_nr
);
3284 remove_eh_landing_pad (lp
);
3289 fprintf (dump_file
, "\n\nAfter removal of unreachable regions:\n");
3290 dump_eh_tree (dump_file
, cfun
);
3291 fprintf (dump_file
, "\n\n");
3294 sbitmap_free (r_reachable
);
3295 sbitmap_free (lp_reachable
);
3297 #ifdef ENABLE_CHECKING
3298 verify_eh_tree (cfun
);
3302 /* Remove regions that do not have landing pads. This assumes
3303 that remove_unreachable_handlers has already been run, and
3304 that we've just manipulated the landing pads since then. */
3307 remove_unreachable_handlers_no_lp (void)
3312 for (i
= 1; VEC_iterate (eh_region
, cfun
->eh
->region_array
, i
, r
); ++i
)
3313 if (r
&& r
->landing_pads
== NULL
&& r
->type
!= ERT_MUST_NOT_THROW
)
3316 fprintf (dump_file
, "Removing unreachable region %d\n", i
);
3317 remove_eh_handler (r
);
3321 /* Undo critical edge splitting on an EH landing pad. Earlier, we
3322 optimisticaly split all sorts of edges, including EH edges. The
3323 optimization passes in between may not have needed them; if not,
3324 we should undo the split.
3326 Recognize this case by having one EH edge incoming to the BB and
3327 one normal edge outgoing; BB should be empty apart from the
3328 post_landing_pad label.
3330 Note that this is slightly different from the empty handler case
3331 handled by cleanup_empty_eh, in that the actual handler may yet
3332 have actual code but the landing pad has been separated from the
3333 handler. As such, cleanup_empty_eh relies on this transformation
3334 having been done first. */
3337 unsplit_eh (eh_landing_pad lp
)
3339 basic_block bb
= label_to_block (lp
->post_landing_pad
);
3340 gimple_stmt_iterator gsi
;
3343 /* Quickly check the edge counts on BB for singularity. */
3344 if (EDGE_COUNT (bb
->preds
) != 1 || EDGE_COUNT (bb
->succs
) != 1)
3346 e_in
= EDGE_PRED (bb
, 0);
3347 e_out
= EDGE_SUCC (bb
, 0);
3349 /* Input edge must be EH and output edge must be normal. */
3350 if ((e_in
->flags
& EDGE_EH
) == 0 || (e_out
->flags
& EDGE_EH
) != 0)
3353 /* The block must be empty except for the labels. */
3354 if (!gsi_end_p (gsi_after_labels (bb
)))
3357 /* The destination block must not already have a landing pad
3358 for a different region. */
3359 for (gsi
= gsi_start_bb (e_out
->dest
); !gsi_end_p (gsi
); gsi_next (&gsi
))
3361 gimple stmt
= gsi_stmt (gsi
);
3365 if (gimple_code (stmt
) != GIMPLE_LABEL
)
3367 lab
= gimple_label_label (stmt
);
3368 lp_nr
= EH_LANDING_PAD_NR (lab
);
3369 if (lp_nr
&& get_eh_region_from_lp_number (lp_nr
) != lp
->region
)
3373 /* The new destination block must not already be a destination of
3374 the source block, lest we merge fallthru and eh edges and get
3375 all sorts of confused. */
3376 if (find_edge (e_in
->src
, e_out
->dest
))
3379 /* ??? We can get degenerate phis due to cfg cleanups. I would have
3380 thought this should have been cleaned up by a phicprop pass, but
3381 that doesn't appear to handle virtuals. Propagate by hand. */
3382 if (!gimple_seq_empty_p (phi_nodes (bb
)))
3384 for (gsi
= gsi_start_phis (bb
); !gsi_end_p (gsi
); )
3386 gimple use_stmt
, phi
= gsi_stmt (gsi
);
3387 tree lhs
= gimple_phi_result (phi
);
3388 tree rhs
= gimple_phi_arg_def (phi
, 0);
3389 use_operand_p use_p
;
3390 imm_use_iterator iter
;
3392 FOR_EACH_IMM_USE_STMT (use_stmt
, iter
, lhs
)
3394 FOR_EACH_IMM_USE_ON_STMT (use_p
, iter
)
3395 SET_USE (use_p
, rhs
);
3398 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (lhs
))
3399 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (rhs
) = 1;
3401 remove_phi_node (&gsi
, true);
3405 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
3406 fprintf (dump_file
, "Unsplit EH landing pad %d to block %i.\n",
3407 lp
->index
, e_out
->dest
->index
);
3409 /* Redirect the edge. Since redirect_eh_edge_1 expects to be moving
3410 a successor edge, humor it. But do the real CFG change with the
3411 predecessor of E_OUT in order to preserve the ordering of arguments
3412 to the PHI nodes in E_OUT->DEST. */
3413 redirect_eh_edge_1 (e_in
, e_out
->dest
, false);
3414 redirect_edge_pred (e_out
, e_in
->src
);
3415 e_out
->flags
= e_in
->flags
;
3416 e_out
->probability
= e_in
->probability
;
3417 e_out
->count
= e_in
->count
;
3423 /* Examine each landing pad block and see if it matches unsplit_eh. */
3426 unsplit_all_eh (void)
3428 bool changed
= false;
3432 for (i
= 1; VEC_iterate (eh_landing_pad
, cfun
->eh
->lp_array
, i
, lp
); ++i
)
3434 changed
|= unsplit_eh (lp
);
3439 /* A subroutine of cleanup_empty_eh. Redirect all EH edges incoming
3440 to OLD_BB to NEW_BB; return true on success, false on failure.
3442 OLD_BB_OUT is the edge into NEW_BB from OLD_BB, so if we miss any
3443 PHI variables from OLD_BB we can pick them up from OLD_BB_OUT.
3444 Virtual PHIs may be deleted and marked for renaming. */
3447 cleanup_empty_eh_merge_phis (basic_block new_bb
, basic_block old_bb
,
3448 edge old_bb_out
, bool change_region
)
3450 gimple_stmt_iterator ngsi
, ogsi
;
3453 bitmap rename_virts
;
3454 bitmap ophi_handled
;
3456 FOR_EACH_EDGE (e
, ei
, old_bb
->preds
)
3457 redirect_edge_var_map_clear (e
);
3459 ophi_handled
= BITMAP_ALLOC (NULL
);
3460 rename_virts
= BITMAP_ALLOC (NULL
);
3462 /* First, iterate through the PHIs on NEW_BB and set up the edge_var_map
3463 for the edges we're going to move. */
3464 for (ngsi
= gsi_start_phis (new_bb
); !gsi_end_p (ngsi
); gsi_next (&ngsi
))
3466 gimple ophi
, nphi
= gsi_stmt (ngsi
);
3469 nresult
= gimple_phi_result (nphi
);
3470 nop
= gimple_phi_arg_def (nphi
, old_bb_out
->dest_idx
);
3472 /* Find the corresponding PHI in OLD_BB so we can forward-propagate
3473 the source ssa_name. */
3475 for (ogsi
= gsi_start_phis (old_bb
); !gsi_end_p (ogsi
); gsi_next (&ogsi
))
3477 ophi
= gsi_stmt (ogsi
);
3478 if (gimple_phi_result (ophi
) == nop
)
3483 /* If we did find the corresponding PHI, copy those inputs. */
3486 bitmap_set_bit (ophi_handled
, SSA_NAME_VERSION (nop
));
3487 FOR_EACH_EDGE (e
, ei
, old_bb
->preds
)
3492 if ((e
->flags
& EDGE_EH
) == 0)
3494 oop
= gimple_phi_arg_def (ophi
, e
->dest_idx
);
3495 oloc
= gimple_phi_arg_location (ophi
, e
->dest_idx
);
3496 redirect_edge_var_map_add (e
, nresult
, oop
, oloc
);
3499 /* If we didn't find the PHI, but it's a VOP, remember to rename
3500 it later, assuming all other tests succeed. */
3501 else if (!is_gimple_reg (nresult
))
3502 bitmap_set_bit (rename_virts
, SSA_NAME_VERSION (nresult
));
3503 /* If we didn't find the PHI, and it's a real variable, we know
3504 from the fact that OLD_BB is tree_empty_eh_handler_p that the
3505 variable is unchanged from input to the block and we can simply
3506 re-use the input to NEW_BB from the OLD_BB_OUT edge. */
3510 = gimple_phi_arg_location (nphi
, old_bb_out
->dest_idx
);
3511 FOR_EACH_EDGE (e
, ei
, old_bb
->preds
)
3512 redirect_edge_var_map_add (e
, nresult
, nop
, nloc
);
3516 /* Second, verify that all PHIs from OLD_BB have been handled. If not,
3517 we don't know what values from the other edges into NEW_BB to use. */
3518 for (ogsi
= gsi_start_phis (old_bb
); !gsi_end_p (ogsi
); gsi_next (&ogsi
))
3520 gimple ophi
= gsi_stmt (ogsi
);
3521 tree oresult
= gimple_phi_result (ophi
);
3522 if (!bitmap_bit_p (ophi_handled
, SSA_NAME_VERSION (oresult
)))
3526 /* At this point we know that the merge will succeed. Remove the PHI
3527 nodes for the virtuals that we want to rename. */
3528 if (!bitmap_empty_p (rename_virts
))
3530 for (ngsi
= gsi_start_phis (new_bb
); !gsi_end_p (ngsi
); )
3532 gimple nphi
= gsi_stmt (ngsi
);
3533 tree nresult
= gimple_phi_result (nphi
);
3534 if (bitmap_bit_p (rename_virts
, SSA_NAME_VERSION (nresult
)))
3536 mark_virtual_phi_result_for_renaming (nphi
);
3537 remove_phi_node (&ngsi
, true);
3544 /* Finally, move the edges and update the PHIs. */
3545 for (ei
= ei_start (old_bb
->preds
); (e
= ei_safe_edge (ei
)); )
3546 if (e
->flags
& EDGE_EH
)
3548 redirect_eh_edge_1 (e
, new_bb
, change_region
);
3549 redirect_edge_succ (e
, new_bb
);
3550 flush_pending_stmts (e
);
3555 BITMAP_FREE (ophi_handled
);
3556 BITMAP_FREE (rename_virts
);
3560 FOR_EACH_EDGE (e
, ei
, old_bb
->preds
)
3561 redirect_edge_var_map_clear (e
);
3562 BITMAP_FREE (ophi_handled
);
3563 BITMAP_FREE (rename_virts
);
3567 /* A subroutine of cleanup_empty_eh. Move a landing pad LP from its
3568 old region to NEW_REGION at BB. */
3571 cleanup_empty_eh_move_lp (basic_block bb
, edge e_out
,
3572 eh_landing_pad lp
, eh_region new_region
)
3574 gimple_stmt_iterator gsi
;
3577 for (pp
= &lp
->region
->landing_pads
; *pp
!= lp
; pp
= &(*pp
)->next_lp
)
3581 lp
->region
= new_region
;
3582 lp
->next_lp
= new_region
->landing_pads
;
3583 new_region
->landing_pads
= lp
;
3585 /* Delete the RESX that was matched within the empty handler block. */
3586 gsi
= gsi_last_bb (bb
);
3587 mark_virtual_ops_for_renaming (gsi_stmt (gsi
));
3588 gsi_remove (&gsi
, true);
3590 /* Clean up E_OUT for the fallthru. */
3591 e_out
->flags
= (e_out
->flags
& ~EDGE_EH
) | EDGE_FALLTHRU
;
3592 e_out
->probability
= REG_BR_PROB_BASE
;
3595 /* A subroutine of cleanup_empty_eh. Handle more complex cases of
3596 unsplitting than unsplit_eh was prepared to handle, e.g. when
3597 multiple incoming edges and phis are involved. */
3600 cleanup_empty_eh_unsplit (basic_block bb
, edge e_out
, eh_landing_pad lp
)
3602 gimple_stmt_iterator gsi
;
3605 /* We really ought not have totally lost everything following
3606 a landing pad label. Given that BB is empty, there had better
3608 gcc_assert (e_out
!= NULL
);
3610 /* The destination block must not already have a landing pad
3611 for a different region. */
3613 for (gsi
= gsi_start_bb (e_out
->dest
); !gsi_end_p (gsi
); gsi_next (&gsi
))
3615 gimple stmt
= gsi_stmt (gsi
);
3618 if (gimple_code (stmt
) != GIMPLE_LABEL
)
3620 lab
= gimple_label_label (stmt
);
3621 lp_nr
= EH_LANDING_PAD_NR (lab
);
3622 if (lp_nr
&& get_eh_region_from_lp_number (lp_nr
) != lp
->region
)
3626 /* Attempt to move the PHIs into the successor block. */
3627 if (cleanup_empty_eh_merge_phis (e_out
->dest
, bb
, e_out
, false))
3629 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
3631 "Unsplit EH landing pad %d to block %i "
3632 "(via cleanup_empty_eh).\n",
3633 lp
->index
, e_out
->dest
->index
);
3640 /* Examine the block associated with LP to determine if it's an empty
3641 handler for its EH region. If so, attempt to redirect EH edges to
3642 an outer region. Return true the CFG was updated in any way. This
3643 is similar to jump forwarding, just across EH edges. */
3646 cleanup_empty_eh (eh_landing_pad lp
)
3648 basic_block bb
= label_to_block (lp
->post_landing_pad
);
3649 gimple_stmt_iterator gsi
;
3651 eh_region new_region
;
3654 bool has_non_eh_pred
;
3657 /* There can be zero or one edges out of BB. This is the quickest test. */
3658 switch (EDGE_COUNT (bb
->succs
))
3664 e_out
= EDGE_SUCC (bb
, 0);
3669 gsi
= gsi_after_labels (bb
);
3671 /* Make sure to skip debug statements. */
3672 if (!gsi_end_p (gsi
) && is_gimple_debug (gsi_stmt (gsi
)))
3673 gsi_next_nondebug (&gsi
);
3675 /* If the block is totally empty, look for more unsplitting cases. */
3676 if (gsi_end_p (gsi
))
3677 return cleanup_empty_eh_unsplit (bb
, e_out
, lp
);
3679 /* The block should consist only of a single RESX statement. */
3680 resx
= gsi_stmt (gsi
);
3681 if (!is_gimple_resx (resx
))
3683 gcc_assert (gsi_one_before_end_p (gsi
));
3685 /* Determine if there are non-EH edges, or resx edges into the handler. */
3686 has_non_eh_pred
= false;
3687 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
3688 if (!(e
->flags
& EDGE_EH
))
3689 has_non_eh_pred
= true;
3691 /* Find the handler that's outer of the empty handler by looking at
3692 where the RESX instruction was vectored. */
3693 new_lp_nr
= lookup_stmt_eh_lp (resx
);
3694 new_region
= get_eh_region_from_lp_number (new_lp_nr
);
3696 /* If there's no destination region within the current function,
3697 redirection is trivial via removing the throwing statements from
3698 the EH region, removing the EH edges, and allowing the block
3699 to go unreachable. */
3700 if (new_region
== NULL
)
3702 gcc_assert (e_out
== NULL
);
3703 for (ei
= ei_start (bb
->preds
); (e
= ei_safe_edge (ei
)); )
3704 if (e
->flags
& EDGE_EH
)
3706 gimple stmt
= last_stmt (e
->src
);
3707 remove_stmt_from_eh_lp (stmt
);
3715 /* If the destination region is a MUST_NOT_THROW, allow the runtime
3716 to handle the abort and allow the blocks to go unreachable. */
3717 if (new_region
->type
== ERT_MUST_NOT_THROW
)
3719 for (ei
= ei_start (bb
->preds
); (e
= ei_safe_edge (ei
)); )
3720 if (e
->flags
& EDGE_EH
)
3722 gimple stmt
= last_stmt (e
->src
);
3723 remove_stmt_from_eh_lp (stmt
);
3724 add_stmt_to_eh_lp (stmt
, new_lp_nr
);
3732 /* Try to redirect the EH edges and merge the PHIs into the destination
3733 landing pad block. If the merge succeeds, we'll already have redirected
3734 all the EH edges. The handler itself will go unreachable if there were
3736 if (cleanup_empty_eh_merge_phis (e_out
->dest
, bb
, e_out
, true))
3739 /* Finally, if all input edges are EH edges, then we can (potentially)
3740 reduce the number of transfers from the runtime by moving the landing
3741 pad from the original region to the new region. This is a win when
3742 we remove the last CLEANUP region along a particular exception
3743 propagation path. Since nothing changes except for the region with
3744 which the landing pad is associated, the PHI nodes do not need to be
3746 if (!has_non_eh_pred
)
3748 cleanup_empty_eh_move_lp (bb
, e_out
, lp
, new_region
);
3749 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
3750 fprintf (dump_file
, "Empty EH handler %i moved to EH region %i.\n",
3751 lp
->index
, new_region
->index
);
3753 /* ??? The CFG didn't change, but we may have rendered the
3754 old EH region unreachable. Trigger a cleanup there. */
3761 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
3762 fprintf (dump_file
, "Empty EH handler %i removed.\n", lp
->index
);
3763 remove_eh_landing_pad (lp
);
3767 /* Do a post-order traversal of the EH region tree. Examine each
3768 post_landing_pad block and see if we can eliminate it as empty. */
3771 cleanup_all_empty_eh (void)
3773 bool changed
= false;
3777 for (i
= 1; VEC_iterate (eh_landing_pad
, cfun
->eh
->lp_array
, i
, lp
); ++i
)
3779 changed
|= cleanup_empty_eh (lp
);
3784 /* Perform cleanups and lowering of exception handling
3785 1) cleanups regions with handlers doing nothing are optimized out
3786 2) MUST_NOT_THROW regions that became dead because of 1) are optimized out
3787 3) Info about regions that are containing instructions, and regions
3788 reachable via local EH edges is collected
3789 4) Eh tree is pruned for regions no longer neccesary.
3791 TODO: Push MUST_NOT_THROW regions to the root of the EH tree.
3792 Unify those that have the same failure decl and locus.
3796 execute_cleanup_eh (void)
3798 /* Do this first: unsplit_all_eh and cleanup_all_empty_eh can die
3799 looking up unreachable landing pads. */
3800 remove_unreachable_handlers ();
3802 /* Watch out for the region tree vanishing due to all unreachable. */
3803 if (cfun
->eh
->region_tree
&& optimize
)
3805 bool changed
= false;
3807 changed
|= unsplit_all_eh ();
3808 changed
|= cleanup_all_empty_eh ();
3812 free_dominance_info (CDI_DOMINATORS
);
3813 free_dominance_info (CDI_POST_DOMINATORS
);
3815 /* We delayed all basic block deletion, as we may have performed
3816 cleanups on EH edges while non-EH edges were still present. */
3817 delete_unreachable_blocks ();
3819 /* We manipulated the landing pads. Remove any region that no
3820 longer has a landing pad. */
3821 remove_unreachable_handlers_no_lp ();
3823 return TODO_cleanup_cfg
| TODO_update_ssa_only_virtuals
;
3831 gate_cleanup_eh (void)
3833 return cfun
->eh
!= NULL
&& cfun
->eh
->region_tree
!= NULL
;
3836 struct gimple_opt_pass pass_cleanup_eh
= {
3839 "ehcleanup", /* name */
3840 gate_cleanup_eh
, /* gate */
3841 execute_cleanup_eh
, /* execute */
3844 0, /* static_pass_number */
3845 TV_TREE_EH
, /* tv_id */
3846 PROP_gimple_lcf
, /* properties_required */
3847 0, /* properties_provided */
3848 0, /* properties_destroyed */
3849 0, /* todo_flags_start */
3850 TODO_dump_func
/* todo_flags_finish */
3854 /* Verify that BB containing STMT as the last statement, has precisely the
3855 edge that make_eh_edges would create. */
3858 verify_eh_edges (gimple stmt
)
3860 basic_block bb
= gimple_bb (stmt
);
3861 eh_landing_pad lp
= NULL
;
3866 lp_nr
= lookup_stmt_eh_lp (stmt
);
3868 lp
= get_eh_landing_pad_from_number (lp_nr
);
3871 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
3873 if (e
->flags
& EDGE_EH
)
3877 error ("BB %i has multiple EH edges", bb
->index
);
3889 error ("BB %i can not throw but has an EH edge", bb
->index
);
3895 if (!stmt_could_throw_p (stmt
))
3897 error ("BB %i last statement has incorrectly set lp", bb
->index
);
3901 if (eh_edge
== NULL
)
3903 error ("BB %i is missing an EH edge", bb
->index
);
3907 if (eh_edge
->dest
!= label_to_block (lp
->post_landing_pad
))
3909 error ("Incorrect EH edge %i->%i", bb
->index
, eh_edge
->dest
->index
);
3916 /* Similarly, but handle GIMPLE_EH_DISPATCH specifically. */
3919 verify_eh_dispatch_edge (gimple stmt
)
3923 basic_block src
, dst
;
3924 bool want_fallthru
= true;
3928 r
= get_eh_region_from_number (gimple_eh_dispatch_region (stmt
));
3929 src
= gimple_bb (stmt
);
3931 FOR_EACH_EDGE (e
, ei
, src
->succs
)
3932 gcc_assert (e
->aux
== NULL
);
3937 for (c
= r
->u
.eh_try
.first_catch
; c
; c
= c
->next_catch
)
3939 dst
= label_to_block (c
->label
);
3940 e
= find_edge (src
, dst
);
3943 error ("BB %i is missing an edge", src
->index
);
3948 /* A catch-all handler doesn't have a fallthru. */
3949 if (c
->type_list
== NULL
)
3951 want_fallthru
= false;
3957 case ERT_ALLOWED_EXCEPTIONS
:
3958 dst
= label_to_block (r
->u
.allowed
.label
);
3959 e
= find_edge (src
, dst
);
3962 error ("BB %i is missing an edge", src
->index
);
3973 FOR_EACH_EDGE (e
, ei
, src
->succs
)
3975 if (e
->flags
& EDGE_FALLTHRU
)
3977 if (fall_edge
!= NULL
)
3979 error ("BB %i too many fallthru edges", src
->index
);
3988 error ("BB %i has incorrect edge", src
->index
);
3992 if ((fall_edge
!= NULL
) ^ want_fallthru
)
3994 error ("BB %i has incorrect fallthru edge", src
->index
);