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 /* Likewise, but reference a tree expression instead. */
209 lookup_expr_eh_lp (tree t
)
211 if (cfun
&& cfun
->eh
->throw_stmt_table
&& t
&& EXPR_P (t
))
213 tree_ann_common_t ann
= tree_common_ann (t
);
221 /* First pass of EH node decomposition. Build up a tree of GIMPLE_TRY_FINALLY
222 nodes and LABEL_DECL nodes. We will use this during the second phase to
223 determine if a goto leaves the body of a TRY_FINALLY_EXPR node. */
225 struct finally_tree_node
227 /* When storing a GIMPLE_TRY, we have to record a gimple. However
228 when deciding whether a GOTO to a certain LABEL_DECL (which is a
229 tree) leaves the TRY block, its necessary to record a tree in
230 this field. Thus a treemple is used. */
235 /* Note that this table is *not* marked GTY. It is short-lived. */
236 static htab_t finally_tree
;
239 record_in_finally_tree (treemple child
, gimple parent
)
241 struct finally_tree_node
*n
;
244 n
= XNEW (struct finally_tree_node
);
248 slot
= htab_find_slot (finally_tree
, n
, INSERT
);
254 collect_finally_tree (gimple stmt
, gimple region
);
256 /* Go through the gimple sequence. Works with collect_finally_tree to
257 record all GIMPLE_LABEL and GIMPLE_TRY statements. */
260 collect_finally_tree_1 (gimple_seq seq
, gimple region
)
262 gimple_stmt_iterator gsi
;
264 for (gsi
= gsi_start (seq
); !gsi_end_p (gsi
); gsi_next (&gsi
))
265 collect_finally_tree (gsi_stmt (gsi
), region
);
269 collect_finally_tree (gimple stmt
, gimple region
)
273 switch (gimple_code (stmt
))
276 temp
.t
= gimple_label_label (stmt
);
277 record_in_finally_tree (temp
, region
);
281 if (gimple_try_kind (stmt
) == GIMPLE_TRY_FINALLY
)
284 record_in_finally_tree (temp
, region
);
285 collect_finally_tree_1 (gimple_try_eval (stmt
), stmt
);
286 collect_finally_tree_1 (gimple_try_cleanup (stmt
), region
);
288 else if (gimple_try_kind (stmt
) == GIMPLE_TRY_CATCH
)
290 collect_finally_tree_1 (gimple_try_eval (stmt
), region
);
291 collect_finally_tree_1 (gimple_try_cleanup (stmt
), region
);
296 collect_finally_tree_1 (gimple_catch_handler (stmt
), region
);
299 case GIMPLE_EH_FILTER
:
300 collect_finally_tree_1 (gimple_eh_filter_failure (stmt
), region
);
304 /* A type, a decl, or some kind of statement that we're not
305 interested in. Don't walk them. */
311 /* Use the finally tree to determine if a jump from START to TARGET
312 would leave the try_finally node that START lives in. */
315 outside_finally_tree (treemple start
, gimple target
)
317 struct finally_tree_node n
, *p
;
322 p
= (struct finally_tree_node
*) htab_find (finally_tree
, &n
);
327 while (start
.g
!= target
);
332 /* Second pass of EH node decomposition. Actually transform the GIMPLE_TRY
333 nodes into a set of gotos, magic labels, and eh regions.
334 The eh region creation is straight-forward, but frobbing all the gotos
335 and such into shape isn't. */
337 /* The sequence into which we record all EH stuff. This will be
338 placed at the end of the function when we're all done. */
339 static gimple_seq eh_seq
;
341 /* Record whether an EH region contains something that can throw,
342 indexed by EH region number. */
343 static bitmap eh_region_may_contain_throw
;
345 /* The GOTO_QUEUE is is an array of GIMPLE_GOTO and GIMPLE_RETURN
346 statements that are seen to escape this GIMPLE_TRY_FINALLY node.
347 The idea is to record a gimple statement for everything except for
348 the conditionals, which get their labels recorded. Since labels are
349 of type 'tree', we need this node to store both gimple and tree
350 objects. REPL_STMT is the sequence used to replace the goto/return
351 statement. CONT_STMT is used to store the statement that allows
352 the return/goto to jump to the original destination. */
354 struct goto_queue_node
357 gimple_seq repl_stmt
;
360 /* This is used when index >= 0 to indicate that stmt is a label (as
361 opposed to a goto stmt). */
365 /* State of the world while lowering. */
369 /* What's "current" while constructing the eh region tree. These
370 correspond to variables of the same name in cfun->eh, which we
371 don't have easy access to. */
372 eh_region cur_region
;
374 /* What's "current" for the purposes of __builtin_eh_pointer. For
375 a CATCH, this is the associated TRY. For an EH_FILTER, this is
376 the associated ALLOWED_EXCEPTIONS, etc. */
377 eh_region ehp_region
;
379 /* Processing of TRY_FINALLY requires a bit more state. This is
380 split out into a separate structure so that we don't have to
381 copy so much when processing other nodes. */
382 struct leh_tf_state
*tf
;
387 /* Pointer to the GIMPLE_TRY_FINALLY node under discussion. The
388 try_finally_expr is the original GIMPLE_TRY_FINALLY. We need to retain
389 this so that outside_finally_tree can reliably reference the tree used
390 in the collect_finally_tree data structures. */
391 gimple try_finally_expr
;
394 /* While lowering a top_p usually it is expanded into multiple statements,
395 thus we need the following field to store them. */
396 gimple_seq top_p_seq
;
398 /* The state outside this try_finally node. */
399 struct leh_state
*outer
;
401 /* The exception region created for it. */
404 /* The goto queue. */
405 struct goto_queue_node
*goto_queue
;
406 size_t goto_queue_size
;
407 size_t goto_queue_active
;
409 /* Pointer map to help in searching goto_queue when it is large. */
410 struct pointer_map_t
*goto_queue_map
;
412 /* The set of unique labels seen as entries in the goto queue. */
413 VEC(tree
,heap
) *dest_array
;
415 /* A label to be added at the end of the completed transformed
416 sequence. It will be set if may_fallthru was true *at one time*,
417 though subsequent transformations may have cleared that flag. */
420 /* True if it is possible to fall out the bottom of the try block.
421 Cleared if the fallthru is converted to a goto. */
424 /* True if any entry in goto_queue is a GIMPLE_RETURN. */
427 /* True if the finally block can receive an exception edge.
428 Cleared if the exception case is handled by code duplication. */
432 static gimple_seq
lower_eh_must_not_throw (struct leh_state
*, gimple
);
434 /* Search for STMT in the goto queue. Return the replacement,
435 or null if the statement isn't in the queue. */
437 #define LARGE_GOTO_QUEUE 20
439 static void lower_eh_constructs_1 (struct leh_state
*state
, gimple_seq seq
);
442 find_goto_replacement (struct leh_tf_state
*tf
, treemple stmt
)
447 if (tf
->goto_queue_active
< LARGE_GOTO_QUEUE
)
449 for (i
= 0; i
< tf
->goto_queue_active
; i
++)
450 if ( tf
->goto_queue
[i
].stmt
.g
== stmt
.g
)
451 return tf
->goto_queue
[i
].repl_stmt
;
455 /* If we have a large number of entries in the goto_queue, create a
456 pointer map and use that for searching. */
458 if (!tf
->goto_queue_map
)
460 tf
->goto_queue_map
= pointer_map_create ();
461 for (i
= 0; i
< tf
->goto_queue_active
; i
++)
463 slot
= pointer_map_insert (tf
->goto_queue_map
,
464 tf
->goto_queue
[i
].stmt
.g
);
465 gcc_assert (*slot
== NULL
);
466 *slot
= &tf
->goto_queue
[i
];
470 slot
= pointer_map_contains (tf
->goto_queue_map
, stmt
.g
);
472 return (((struct goto_queue_node
*) *slot
)->repl_stmt
);
477 /* A subroutine of replace_goto_queue_1. Handles the sub-clauses of a
478 lowered GIMPLE_COND. If, by chance, the replacement is a simple goto,
479 then we can just splat it in, otherwise we add the new stmts immediately
480 after the GIMPLE_COND and redirect. */
483 replace_goto_queue_cond_clause (tree
*tp
, struct leh_tf_state
*tf
,
484 gimple_stmt_iterator
*gsi
)
489 location_t loc
= gimple_location (gsi_stmt (*gsi
));
492 new_seq
= find_goto_replacement (tf
, temp
);
496 if (gimple_seq_singleton_p (new_seq
)
497 && gimple_code (gimple_seq_first_stmt (new_seq
)) == GIMPLE_GOTO
)
499 *tp
= gimple_goto_dest (gimple_seq_first_stmt (new_seq
));
503 label
= create_artificial_label (loc
);
504 /* Set the new label for the GIMPLE_COND */
507 gsi_insert_after (gsi
, gimple_build_label (label
), GSI_CONTINUE_LINKING
);
508 gsi_insert_seq_after (gsi
, gimple_seq_copy (new_seq
), GSI_CONTINUE_LINKING
);
511 /* The real work of replace_goto_queue. Returns with TSI updated to
512 point to the next statement. */
514 static void replace_goto_queue_stmt_list (gimple_seq
, struct leh_tf_state
*);
517 replace_goto_queue_1 (gimple stmt
, struct leh_tf_state
*tf
,
518 gimple_stmt_iterator
*gsi
)
524 switch (gimple_code (stmt
))
529 seq
= find_goto_replacement (tf
, temp
);
532 gsi_insert_seq_before (gsi
, gimple_seq_copy (seq
), GSI_SAME_STMT
);
533 gsi_remove (gsi
, false);
539 replace_goto_queue_cond_clause (gimple_op_ptr (stmt
, 2), tf
, gsi
);
540 replace_goto_queue_cond_clause (gimple_op_ptr (stmt
, 3), tf
, gsi
);
544 replace_goto_queue_stmt_list (gimple_try_eval (stmt
), tf
);
545 replace_goto_queue_stmt_list (gimple_try_cleanup (stmt
), tf
);
548 replace_goto_queue_stmt_list (gimple_catch_handler (stmt
), tf
);
550 case GIMPLE_EH_FILTER
:
551 replace_goto_queue_stmt_list (gimple_eh_filter_failure (stmt
), tf
);
555 /* These won't have gotos in them. */
562 /* A subroutine of replace_goto_queue. Handles GIMPLE_SEQ. */
565 replace_goto_queue_stmt_list (gimple_seq seq
, struct leh_tf_state
*tf
)
567 gimple_stmt_iterator gsi
= gsi_start (seq
);
569 while (!gsi_end_p (gsi
))
570 replace_goto_queue_1 (gsi_stmt (gsi
), tf
, &gsi
);
573 /* Replace all goto queue members. */
576 replace_goto_queue (struct leh_tf_state
*tf
)
578 if (tf
->goto_queue_active
== 0)
580 replace_goto_queue_stmt_list (tf
->top_p_seq
, tf
);
583 /* Add a new record to the goto queue contained in TF. NEW_STMT is the
584 data to be added, IS_LABEL indicates whether NEW_STMT is a label or
588 record_in_goto_queue (struct leh_tf_state
*tf
,
594 struct goto_queue_node
*q
;
596 gcc_assert (!tf
->goto_queue_map
);
598 active
= tf
->goto_queue_active
;
599 size
= tf
->goto_queue_size
;
602 size
= (size
? size
* 2 : 32);
603 tf
->goto_queue_size
= size
;
605 = XRESIZEVEC (struct goto_queue_node
, tf
->goto_queue
, size
);
608 q
= &tf
->goto_queue
[active
];
609 tf
->goto_queue_active
= active
+ 1;
611 memset (q
, 0, sizeof (*q
));
614 q
->is_label
= is_label
;
617 /* Record the LABEL label in the goto queue contained in TF.
621 record_in_goto_queue_label (struct leh_tf_state
*tf
, treemple stmt
, tree label
)
624 treemple temp
, new_stmt
;
629 /* Computed and non-local gotos do not get processed. Given
630 their nature we can neither tell whether we've escaped the
631 finally block nor redirect them if we knew. */
632 if (TREE_CODE (label
) != LABEL_DECL
)
635 /* No need to record gotos that don't leave the try block. */
637 if (!outside_finally_tree (temp
, tf
->try_finally_expr
))
640 if (! tf
->dest_array
)
642 tf
->dest_array
= VEC_alloc (tree
, heap
, 10);
643 VEC_quick_push (tree
, tf
->dest_array
, label
);
648 int n
= VEC_length (tree
, tf
->dest_array
);
649 for (index
= 0; index
< n
; ++index
)
650 if (VEC_index (tree
, tf
->dest_array
, index
) == label
)
653 VEC_safe_push (tree
, heap
, tf
->dest_array
, label
);
656 /* In the case of a GOTO we want to record the destination label,
657 since with a GIMPLE_COND we have an easy access to the then/else
660 record_in_goto_queue (tf
, new_stmt
, index
, true);
664 /* For any GIMPLE_GOTO or GIMPLE_RETURN, decide whether it leaves a try_finally
665 node, and if so record that fact in the goto queue associated with that
669 maybe_record_in_goto_queue (struct leh_state
*state
, gimple stmt
)
671 struct leh_tf_state
*tf
= state
->tf
;
677 switch (gimple_code (stmt
))
680 new_stmt
.tp
= gimple_op_ptr (stmt
, 2);
681 record_in_goto_queue_label (tf
, new_stmt
, gimple_cond_true_label (stmt
));
682 new_stmt
.tp
= gimple_op_ptr (stmt
, 3);
683 record_in_goto_queue_label (tf
, new_stmt
, gimple_cond_false_label (stmt
));
687 record_in_goto_queue_label (tf
, new_stmt
, gimple_goto_dest (stmt
));
691 tf
->may_return
= true;
693 record_in_goto_queue (tf
, new_stmt
, -1, false);
702 #ifdef ENABLE_CHECKING
703 /* We do not process GIMPLE_SWITCHes for now. As long as the original source
704 was in fact structured, and we've not yet done jump threading, then none
705 of the labels will leave outer GIMPLE_TRY_FINALLY nodes. Verify this. */
708 verify_norecord_switch_expr (struct leh_state
*state
, gimple switch_expr
)
710 struct leh_tf_state
*tf
= state
->tf
;
716 n
= gimple_switch_num_labels (switch_expr
);
718 for (i
= 0; i
< n
; ++i
)
721 tree lab
= CASE_LABEL (gimple_switch_label (switch_expr
, i
));
723 gcc_assert (!outside_finally_tree (temp
, tf
->try_finally_expr
));
727 #define verify_norecord_switch_expr(state, switch_expr)
730 /* Redirect a RETURN_EXPR pointed to by STMT_P to FINLAB. Place in CONT_P
731 whatever is needed to finish the return. If MOD is non-null, insert it
732 before the new branch. RETURN_VALUE_P is a cache containing a temporary
733 variable to be used in manipulating the value returned from the function. */
736 do_return_redirection (struct goto_queue_node
*q
, tree finlab
, gimple_seq mod
,
737 tree
*return_value_p
)
742 /* In the case of a return, the queue node must be a gimple statement. */
743 gcc_assert (!q
->is_label
);
745 ret_expr
= gimple_return_retval (q
->stmt
.g
);
749 if (!*return_value_p
)
750 *return_value_p
= ret_expr
;
752 gcc_assert (*return_value_p
== ret_expr
);
753 q
->cont_stmt
= q
->stmt
.g
;
754 /* The nasty part about redirecting the return value is that the
755 return value itself is to be computed before the FINALLY block
769 should return 0, not 1. Arrange for this to happen by copying
770 computed the return value into a local temporary. This also
771 allows us to redirect multiple return statements through the
772 same destination block; whether this is a net win or not really
773 depends, I guess, but it does make generation of the switch in
774 lower_try_finally_switch easier. */
776 if (TREE_CODE (ret_expr
) == RESULT_DECL
)
778 if (!*return_value_p
)
779 *return_value_p
= ret_expr
;
781 gcc_assert (*return_value_p
== ret_expr
);
782 q
->cont_stmt
= q
->stmt
.g
;
788 /* If we don't return a value, all return statements are the same. */
789 q
->cont_stmt
= q
->stmt
.g
;
792 q
->repl_stmt
= gimple_seq_alloc ();
795 gimple_seq_add_seq (&q
->repl_stmt
, mod
);
797 x
= gimple_build_goto (finlab
);
798 gimple_seq_add_stmt (&q
->repl_stmt
, x
);
801 /* Similar, but easier, for GIMPLE_GOTO. */
804 do_goto_redirection (struct goto_queue_node
*q
, tree finlab
, gimple_seq mod
,
805 struct leh_tf_state
*tf
)
809 gcc_assert (q
->is_label
);
811 q
->repl_stmt
= gimple_seq_alloc ();
813 q
->cont_stmt
= gimple_build_goto (VEC_index (tree
, tf
->dest_array
, q
->index
));
816 gimple_seq_add_seq (&q
->repl_stmt
, mod
);
818 x
= gimple_build_goto (finlab
);
819 gimple_seq_add_stmt (&q
->repl_stmt
, x
);
822 /* Emit a standard landing pad sequence into SEQ for REGION. */
825 emit_post_landing_pad (gimple_seq
*seq
, eh_region region
)
827 eh_landing_pad lp
= region
->landing_pads
;
831 lp
= gen_eh_landing_pad (region
);
833 lp
->post_landing_pad
= create_artificial_label (UNKNOWN_LOCATION
);
834 EH_LANDING_PAD_NR (lp
->post_landing_pad
) = lp
->index
;
836 x
= gimple_build_label (lp
->post_landing_pad
);
837 gimple_seq_add_stmt (seq
, x
);
840 /* Emit a RESX statement into SEQ for REGION. */
843 emit_resx (gimple_seq
*seq
, eh_region region
)
845 gimple x
= gimple_build_resx (region
->index
);
846 gimple_seq_add_stmt (seq
, x
);
848 record_stmt_eh_region (region
->outer
, x
);
851 /* Emit an EH_DISPATCH statement into SEQ for REGION. */
854 emit_eh_dispatch (gimple_seq
*seq
, eh_region region
)
856 gimple x
= gimple_build_eh_dispatch (region
->index
);
857 gimple_seq_add_stmt (seq
, x
);
860 /* Note that the current EH region may contain a throw, or a
861 call to a function which itself may contain a throw. */
864 note_eh_region_may_contain_throw (eh_region region
)
866 while (!bitmap_bit_p (eh_region_may_contain_throw
, region
->index
))
868 bitmap_set_bit (eh_region_may_contain_throw
, region
->index
);
869 region
= region
->outer
;
875 /* We want to transform
876 try { body; } catch { stuff; }
886 TP is a GIMPLE_TRY node. REGION is the region whose post_landing_pad
887 should be placed before the second operand, or NULL. OVER is
888 an existing label that should be put at the exit, or NULL. */
891 frob_into_branch_around (gimple tp
, eh_region region
, tree over
)
894 gimple_seq cleanup
, result
;
895 location_t loc
= gimple_location (tp
);
897 cleanup
= gimple_try_cleanup (tp
);
898 result
= gimple_try_eval (tp
);
901 emit_post_landing_pad (&eh_seq
, region
);
903 if (gimple_seq_may_fallthru (cleanup
))
906 over
= create_artificial_label (loc
);
907 x
= gimple_build_goto (over
);
908 gimple_seq_add_stmt (&cleanup
, x
);
910 gimple_seq_add_seq (&eh_seq
, cleanup
);
914 x
= gimple_build_label (over
);
915 gimple_seq_add_stmt (&result
, x
);
920 /* A subroutine of lower_try_finally. Duplicate the tree rooted at T.
921 Make sure to record all new labels found. */
924 lower_try_finally_dup_block (gimple_seq seq
, struct leh_state
*outer_state
)
926 gimple region
= NULL
;
929 new_seq
= copy_gimple_seq_and_replace_locals (seq
);
932 region
= outer_state
->tf
->try_finally_expr
;
933 collect_finally_tree_1 (new_seq
, region
);
938 /* A subroutine of lower_try_finally. Create a fallthru label for
939 the given try_finally state. The only tricky bit here is that
940 we have to make sure to record the label in our outer context. */
943 lower_try_finally_fallthru_label (struct leh_tf_state
*tf
)
945 tree label
= tf
->fallthru_label
;
950 label
= create_artificial_label (gimple_location (tf
->try_finally_expr
));
951 tf
->fallthru_label
= label
;
955 record_in_finally_tree (temp
, tf
->outer
->tf
->try_finally_expr
);
961 /* A subroutine of lower_try_finally. If lang_protect_cleanup_actions
962 returns non-null, then the language requires that the exception path out
963 of a try_finally be treated specially. To wit: the code within the
964 finally block may not itself throw an exception. We have two choices here.
965 First we can duplicate the finally block and wrap it in a must_not_throw
966 region. Second, we can generate code like
971 if (fintmp == eh_edge)
972 protect_cleanup_actions;
975 where "fintmp" is the temporary used in the switch statement generation
976 alternative considered below. For the nonce, we always choose the first
979 THIS_STATE may be null if this is a try-cleanup, not a try-finally. */
982 honor_protect_cleanup_actions (struct leh_state
*outer_state
,
983 struct leh_state
*this_state
,
984 struct leh_tf_state
*tf
)
986 tree protect_cleanup_actions
;
987 gimple_stmt_iterator gsi
;
988 bool finally_may_fallthru
;
992 /* First check for nothing to do. */
993 if (lang_protect_cleanup_actions
== NULL
)
995 protect_cleanup_actions
= lang_protect_cleanup_actions ();
996 if (protect_cleanup_actions
== NULL
)
999 finally
= gimple_try_cleanup (tf
->top_p
);
1000 finally_may_fallthru
= gimple_seq_may_fallthru (finally
);
1002 /* Duplicate the FINALLY block. Only need to do this for try-finally,
1003 and not for cleanups. */
1005 finally
= lower_try_finally_dup_block (finally
, outer_state
);
1007 /* If this cleanup consists of a TRY_CATCH_EXPR with TRY_CATCH_IS_CLEANUP
1008 set, the handler of the TRY_CATCH_EXPR is another cleanup which ought
1009 to be in an enclosing scope, but needs to be implemented at this level
1010 to avoid a nesting violation (see wrap_temporary_cleanups in
1011 cp/decl.c). Since it's logically at an outer level, we should call
1012 terminate before we get to it, so strip it away before adding the
1013 MUST_NOT_THROW filter. */
1014 gsi
= gsi_start (finally
);
1016 if (gimple_code (x
) == GIMPLE_TRY
1017 && gimple_try_kind (x
) == GIMPLE_TRY_CATCH
1018 && gimple_try_catch_is_cleanup (x
))
1020 gsi_insert_seq_before (&gsi
, gimple_try_eval (x
), GSI_SAME_STMT
);
1021 gsi_remove (&gsi
, false);
1024 /* Wrap the block with protect_cleanup_actions as the action. */
1025 x
= gimple_build_eh_must_not_throw (protect_cleanup_actions
);
1026 x
= gimple_build_try (finally
, gimple_seq_alloc_with_stmt (x
),
1028 finally
= lower_eh_must_not_throw (outer_state
, x
);
1030 /* Drop all of this into the exception sequence. */
1031 emit_post_landing_pad (&eh_seq
, tf
->region
);
1032 gimple_seq_add_seq (&eh_seq
, finally
);
1033 if (finally_may_fallthru
)
1034 emit_resx (&eh_seq
, tf
->region
);
1036 /* Having now been handled, EH isn't to be considered with
1037 the rest of the outgoing edges. */
1038 tf
->may_throw
= false;
1041 /* A subroutine of lower_try_finally. We have determined that there is
1042 no fallthru edge out of the finally block. This means that there is
1043 no outgoing edge corresponding to any incoming edge. Restructure the
1044 try_finally node for this special case. */
1047 lower_try_finally_nofallthru (struct leh_state
*state
,
1048 struct leh_tf_state
*tf
)
1050 tree lab
, return_val
;
1053 struct goto_queue_node
*q
, *qe
;
1055 lab
= create_artificial_label (gimple_location (tf
->try_finally_expr
));
1057 /* We expect that tf->top_p is a GIMPLE_TRY. */
1058 finally
= gimple_try_cleanup (tf
->top_p
);
1059 tf
->top_p_seq
= gimple_try_eval (tf
->top_p
);
1061 x
= gimple_build_label (lab
);
1062 gimple_seq_add_stmt (&tf
->top_p_seq
, x
);
1066 qe
= q
+ tf
->goto_queue_active
;
1069 do_return_redirection (q
, lab
, NULL
, &return_val
);
1071 do_goto_redirection (q
, lab
, NULL
, tf
);
1073 replace_goto_queue (tf
);
1075 lower_eh_constructs_1 (state
, finally
);
1076 gimple_seq_add_seq (&tf
->top_p_seq
, finally
);
1080 emit_post_landing_pad (&eh_seq
, tf
->region
);
1082 x
= gimple_build_goto (lab
);
1083 gimple_seq_add_stmt (&eh_seq
, x
);
1087 /* A subroutine of lower_try_finally. We have determined that there is
1088 exactly one destination of the finally block. Restructure the
1089 try_finally node for this special case. */
1092 lower_try_finally_onedest (struct leh_state
*state
, struct leh_tf_state
*tf
)
1094 struct goto_queue_node
*q
, *qe
;
1098 location_t loc
= gimple_location (tf
->try_finally_expr
);
1100 finally
= gimple_try_cleanup (tf
->top_p
);
1101 tf
->top_p_seq
= gimple_try_eval (tf
->top_p
);
1103 lower_eh_constructs_1 (state
, finally
);
1107 /* Only reachable via the exception edge. Add the given label to
1108 the head of the FINALLY block. Append a RESX at the end. */
1109 emit_post_landing_pad (&eh_seq
, tf
->region
);
1110 gimple_seq_add_seq (&eh_seq
, finally
);
1111 emit_resx (&eh_seq
, tf
->region
);
1115 if (tf
->may_fallthru
)
1117 /* Only reachable via the fallthru edge. Do nothing but let
1118 the two blocks run together; we'll fall out the bottom. */
1119 gimple_seq_add_seq (&tf
->top_p_seq
, finally
);
1123 finally_label
= create_artificial_label (loc
);
1124 x
= gimple_build_label (finally_label
);
1125 gimple_seq_add_stmt (&tf
->top_p_seq
, x
);
1127 gimple_seq_add_seq (&tf
->top_p_seq
, finally
);
1130 qe
= q
+ tf
->goto_queue_active
;
1134 /* Reachable by return expressions only. Redirect them. */
1135 tree return_val
= NULL
;
1137 do_return_redirection (q
, finally_label
, NULL
, &return_val
);
1138 replace_goto_queue (tf
);
1142 /* Reachable by goto expressions only. Redirect them. */
1144 do_goto_redirection (q
, finally_label
, NULL
, tf
);
1145 replace_goto_queue (tf
);
1147 if (VEC_index (tree
, tf
->dest_array
, 0) == tf
->fallthru_label
)
1149 /* Reachable by goto to fallthru label only. Redirect it
1150 to the new label (already created, sadly), and do not
1151 emit the final branch out, or the fallthru label. */
1152 tf
->fallthru_label
= NULL
;
1157 /* Place the original return/goto to the original destination
1158 immediately after the finally block. */
1159 x
= tf
->goto_queue
[0].cont_stmt
;
1160 gimple_seq_add_stmt (&tf
->top_p_seq
, x
);
1161 maybe_record_in_goto_queue (state
, x
);
1164 /* A subroutine of lower_try_finally. There are multiple edges incoming
1165 and outgoing from the finally block. Implement this by duplicating the
1166 finally block for every destination. */
1169 lower_try_finally_copy (struct leh_state
*state
, struct leh_tf_state
*tf
)
1172 gimple_seq new_stmt
;
1176 location_t tf_loc
= gimple_location (tf
->try_finally_expr
);
1178 finally
= gimple_try_cleanup (tf
->top_p
);
1179 tf
->top_p_seq
= gimple_try_eval (tf
->top_p
);
1182 if (tf
->may_fallthru
)
1184 seq
= lower_try_finally_dup_block (finally
, state
);
1185 lower_eh_constructs_1 (state
, seq
);
1186 gimple_seq_add_seq (&new_stmt
, seq
);
1188 tmp
= lower_try_finally_fallthru_label (tf
);
1189 x
= gimple_build_goto (tmp
);
1190 gimple_seq_add_stmt (&new_stmt
, x
);
1195 emit_post_landing_pad (&eh_seq
, tf
->region
);
1197 seq
= lower_try_finally_dup_block (finally
, state
);
1198 lower_eh_constructs_1 (state
, seq
);
1199 gimple_seq_add_seq (&eh_seq
, seq
);
1201 emit_resx (&eh_seq
, tf
->region
);
1206 struct goto_queue_node
*q
, *qe
;
1207 tree return_val
= NULL
;
1208 int return_index
, index
;
1211 struct goto_queue_node
*q
;
1215 return_index
= VEC_length (tree
, tf
->dest_array
);
1216 labels
= XCNEWVEC (struct labels_s
, return_index
+ 1);
1219 qe
= q
+ tf
->goto_queue_active
;
1222 index
= q
->index
< 0 ? return_index
: q
->index
;
1224 if (!labels
[index
].q
)
1225 labels
[index
].q
= q
;
1228 for (index
= 0; index
< return_index
+ 1; index
++)
1232 q
= labels
[index
].q
;
1236 lab
= labels
[index
].label
1237 = create_artificial_label (tf_loc
);
1239 if (index
== return_index
)
1240 do_return_redirection (q
, lab
, NULL
, &return_val
);
1242 do_goto_redirection (q
, lab
, NULL
, tf
);
1244 x
= gimple_build_label (lab
);
1245 gimple_seq_add_stmt (&new_stmt
, x
);
1247 seq
= lower_try_finally_dup_block (finally
, state
);
1248 lower_eh_constructs_1 (state
, seq
);
1249 gimple_seq_add_seq (&new_stmt
, seq
);
1251 gimple_seq_add_stmt (&new_stmt
, q
->cont_stmt
);
1252 maybe_record_in_goto_queue (state
, q
->cont_stmt
);
1255 for (q
= tf
->goto_queue
; q
< qe
; q
++)
1259 index
= q
->index
< 0 ? return_index
: q
->index
;
1261 if (labels
[index
].q
== q
)
1264 lab
= labels
[index
].label
;
1266 if (index
== return_index
)
1267 do_return_redirection (q
, lab
, NULL
, &return_val
);
1269 do_goto_redirection (q
, lab
, NULL
, tf
);
1272 replace_goto_queue (tf
);
1276 /* Need to link new stmts after running replace_goto_queue due
1277 to not wanting to process the same goto stmts twice. */
1278 gimple_seq_add_seq (&tf
->top_p_seq
, new_stmt
);
1281 /* A subroutine of lower_try_finally. There are multiple edges incoming
1282 and outgoing from the finally block. Implement this by instrumenting
1283 each incoming edge and creating a switch statement at the end of the
1284 finally block that branches to the appropriate destination. */
1287 lower_try_finally_switch (struct leh_state
*state
, struct leh_tf_state
*tf
)
1289 struct goto_queue_node
*q
, *qe
;
1290 tree return_val
= NULL
;
1291 tree finally_tmp
, finally_label
;
1292 int return_index
, eh_index
, fallthru_index
;
1293 int nlabels
, ndests
, j
, last_case_index
;
1295 VEC (tree
,heap
) *case_label_vec
;
1296 gimple_seq switch_body
;
1301 struct pointer_map_t
*cont_map
= NULL
;
1302 /* The location of the TRY_FINALLY stmt. */
1303 location_t tf_loc
= gimple_location (tf
->try_finally_expr
);
1304 /* The location of the finally block. */
1305 location_t finally_loc
;
1307 switch_body
= gimple_seq_alloc ();
1309 /* Mash the TRY block to the head of the chain. */
1310 finally
= gimple_try_cleanup (tf
->top_p
);
1311 tf
->top_p_seq
= gimple_try_eval (tf
->top_p
);
1313 /* The location of the finally is either the last stmt in the finally
1314 block or the location of the TRY_FINALLY itself. */
1315 finally_loc
= gimple_seq_last_stmt (tf
->top_p_seq
) != NULL
?
1316 gimple_location (gimple_seq_last_stmt (tf
->top_p_seq
))
1319 /* Lower the finally block itself. */
1320 lower_eh_constructs_1 (state
, finally
);
1322 /* Prepare for switch statement generation. */
1323 nlabels
= VEC_length (tree
, tf
->dest_array
);
1324 return_index
= nlabels
;
1325 eh_index
= return_index
+ tf
->may_return
;
1326 fallthru_index
= eh_index
+ tf
->may_throw
;
1327 ndests
= fallthru_index
+ tf
->may_fallthru
;
1329 finally_tmp
= create_tmp_var (integer_type_node
, "finally_tmp");
1330 finally_label
= create_artificial_label (finally_loc
);
1332 /* We use VEC_quick_push on case_label_vec throughout this function,
1333 since we know the size in advance and allocate precisely as muce
1335 case_label_vec
= VEC_alloc (tree
, heap
, ndests
);
1337 last_case_index
= 0;
1339 /* Begin inserting code for getting to the finally block. Things
1340 are done in this order to correspond to the sequence the code is
1343 if (tf
->may_fallthru
)
1345 x
= gimple_build_assign (finally_tmp
,
1346 build_int_cst (NULL
, fallthru_index
));
1347 gimple_seq_add_stmt (&tf
->top_p_seq
, x
);
1349 last_case
= build3 (CASE_LABEL_EXPR
, void_type_node
,
1350 build_int_cst (NULL
, fallthru_index
),
1351 NULL
, create_artificial_label (tf_loc
));
1352 VEC_quick_push (tree
, case_label_vec
, last_case
);
1355 x
= gimple_build_label (CASE_LABEL (last_case
));
1356 gimple_seq_add_stmt (&switch_body
, x
);
1358 tmp
= lower_try_finally_fallthru_label (tf
);
1359 x
= gimple_build_goto (tmp
);
1360 gimple_seq_add_stmt (&switch_body
, x
);
1365 emit_post_landing_pad (&eh_seq
, tf
->region
);
1367 x
= gimple_build_assign (finally_tmp
,
1368 build_int_cst (NULL
, eh_index
));
1369 gimple_seq_add_stmt (&eh_seq
, x
);
1371 x
= gimple_build_goto (finally_label
);
1372 gimple_seq_add_stmt (&eh_seq
, x
);
1374 last_case
= build3 (CASE_LABEL_EXPR
, void_type_node
,
1375 build_int_cst (NULL
, eh_index
),
1376 NULL
, create_artificial_label (tf_loc
));
1377 VEC_quick_push (tree
, case_label_vec
, last_case
);
1380 x
= gimple_build_label (CASE_LABEL (last_case
));
1381 gimple_seq_add_stmt (&eh_seq
, x
);
1382 emit_resx (&eh_seq
, tf
->region
);
1385 x
= gimple_build_label (finally_label
);
1386 gimple_seq_add_stmt (&tf
->top_p_seq
, x
);
1388 gimple_seq_add_seq (&tf
->top_p_seq
, finally
);
1390 /* Redirect each incoming goto edge. */
1392 qe
= q
+ tf
->goto_queue_active
;
1393 j
= last_case_index
+ tf
->may_return
;
1394 /* Prepare the assignments to finally_tmp that are executed upon the
1395 entrance through a particular edge. */
1400 unsigned int case_index
;
1402 mod
= gimple_seq_alloc ();
1406 x
= gimple_build_assign (finally_tmp
,
1407 build_int_cst (NULL
, return_index
));
1408 gimple_seq_add_stmt (&mod
, x
);
1409 do_return_redirection (q
, finally_label
, mod
, &return_val
);
1410 switch_id
= return_index
;
1414 x
= gimple_build_assign (finally_tmp
,
1415 build_int_cst (NULL
, q
->index
));
1416 gimple_seq_add_stmt (&mod
, x
);
1417 do_goto_redirection (q
, finally_label
, mod
, tf
);
1418 switch_id
= q
->index
;
1421 case_index
= j
+ q
->index
;
1422 if (VEC_length (tree
, case_label_vec
) <= case_index
1423 || !VEC_index (tree
, case_label_vec
, case_index
))
1427 case_lab
= build3 (CASE_LABEL_EXPR
, void_type_node
,
1428 build_int_cst (NULL
, switch_id
),
1430 /* We store the cont_stmt in the pointer map, so that we can recover
1431 it in the loop below. We don't create the new label while
1432 walking the goto_queue because pointers don't offer a stable
1435 cont_map
= pointer_map_create ();
1436 slot
= pointer_map_insert (cont_map
, case_lab
);
1437 *slot
= q
->cont_stmt
;
1438 VEC_quick_push (tree
, case_label_vec
, case_lab
);
1441 for (j
= last_case_index
; j
< last_case_index
+ nlabels
; j
++)
1447 last_case
= VEC_index (tree
, case_label_vec
, j
);
1449 gcc_assert (last_case
);
1450 gcc_assert (cont_map
);
1452 slot
= pointer_map_contains (cont_map
, last_case
);
1453 /* As the comment above suggests, CASE_LABEL (last_case) was just a
1454 placeholder, it does not store an actual label, yet. */
1456 cont_stmt
= *(gimple
*) slot
;
1458 label
= create_artificial_label (tf_loc
);
1459 CASE_LABEL (last_case
) = label
;
1461 x
= gimple_build_label (label
);
1462 gimple_seq_add_stmt (&switch_body
, x
);
1463 gimple_seq_add_stmt (&switch_body
, cont_stmt
);
1464 maybe_record_in_goto_queue (state
, cont_stmt
);
1467 pointer_map_destroy (cont_map
);
1469 replace_goto_queue (tf
);
1471 /* Make sure that the last case is the default label, as one is required.
1472 Then sort the labels, which is also required in GIMPLE. */
1473 CASE_LOW (last_case
) = NULL
;
1474 sort_case_labels (case_label_vec
);
1476 /* Build the switch statement, setting last_case to be the default
1478 switch_stmt
= gimple_build_switch_vec (finally_tmp
, last_case
,
1480 gimple_set_location (switch_stmt
, finally_loc
);
1482 /* Need to link SWITCH_STMT after running replace_goto_queue
1483 due to not wanting to process the same goto stmts twice. */
1484 gimple_seq_add_stmt (&tf
->top_p_seq
, switch_stmt
);
1485 gimple_seq_add_seq (&tf
->top_p_seq
, switch_body
);
1488 /* Decide whether or not we are going to duplicate the finally block.
1489 There are several considerations.
1491 First, if this is Java, then the finally block contains code
1492 written by the user. It has line numbers associated with it,
1493 so duplicating the block means it's difficult to set a breakpoint.
1494 Since controlling code generation via -g is verboten, we simply
1495 never duplicate code without optimization.
1497 Second, we'd like to prevent egregious code growth. One way to
1498 do this is to estimate the size of the finally block, multiply
1499 that by the number of copies we'd need to make, and compare against
1500 the estimate of the size of the switch machinery we'd have to add. */
1503 decide_copy_try_finally (int ndests
, gimple_seq finally
)
1505 int f_estimate
, sw_estimate
;
1510 /* Finally estimate N times, plus N gotos. */
1511 f_estimate
= count_insns_seq (finally
, &eni_size_weights
);
1512 f_estimate
= (f_estimate
+ 1) * ndests
;
1514 /* Switch statement (cost 10), N variable assignments, N gotos. */
1515 sw_estimate
= 10 + 2 * ndests
;
1517 /* Optimize for size clearly wants our best guess. */
1518 if (optimize_function_for_size_p (cfun
))
1519 return f_estimate
< sw_estimate
;
1521 /* ??? These numbers are completely made up so far. */
1523 return f_estimate
< 100 || f_estimate
< sw_estimate
* 2;
1525 return f_estimate
< 40 || f_estimate
* 2 < sw_estimate
* 3;
1529 /* A subroutine of lower_eh_constructs_1. Lower a GIMPLE_TRY_FINALLY nodes
1530 to a sequence of labels and blocks, plus the exception region trees
1531 that record all the magic. This is complicated by the need to
1532 arrange for the FINALLY block to be executed on all exits. */
1535 lower_try_finally (struct leh_state
*state
, gimple tp
)
1537 struct leh_tf_state this_tf
;
1538 struct leh_state this_state
;
1541 /* Process the try block. */
1543 memset (&this_tf
, 0, sizeof (this_tf
));
1544 this_tf
.try_finally_expr
= tp
;
1546 this_tf
.outer
= state
;
1547 if (using_eh_for_cleanups_p
)
1548 this_tf
.region
= gen_eh_region_cleanup (state
->cur_region
);
1550 this_tf
.region
= NULL
;
1552 this_state
.cur_region
= this_tf
.region
;
1553 this_state
.ehp_region
= state
->ehp_region
;
1554 this_state
.tf
= &this_tf
;
1556 lower_eh_constructs_1 (&this_state
, gimple_try_eval(tp
));
1558 /* Determine if the try block is escaped through the bottom. */
1559 this_tf
.may_fallthru
= gimple_seq_may_fallthru (gimple_try_eval (tp
));
1561 /* Determine if any exceptions are possible within the try block. */
1562 if (using_eh_for_cleanups_p
)
1563 this_tf
.may_throw
= bitmap_bit_p (eh_region_may_contain_throw
,
1564 this_tf
.region
->index
);
1565 if (this_tf
.may_throw
)
1566 honor_protect_cleanup_actions (state
, &this_state
, &this_tf
);
1568 /* Determine how many edges (still) reach the finally block. Or rather,
1569 how many destinations are reached by the finally block. Use this to
1570 determine how we process the finally block itself. */
1572 ndests
= VEC_length (tree
, this_tf
.dest_array
);
1573 ndests
+= this_tf
.may_fallthru
;
1574 ndests
+= this_tf
.may_return
;
1575 ndests
+= this_tf
.may_throw
;
1577 /* If the FINALLY block is not reachable, dike it out. */
1580 gimple_seq_add_seq (&this_tf
.top_p_seq
, gimple_try_eval (tp
));
1581 gimple_try_set_cleanup (tp
, NULL
);
1583 /* If the finally block doesn't fall through, then any destination
1584 we might try to impose there isn't reached either. There may be
1585 some minor amount of cleanup and redirection still needed. */
1586 else if (!gimple_seq_may_fallthru (gimple_try_cleanup (tp
)))
1587 lower_try_finally_nofallthru (state
, &this_tf
);
1589 /* We can easily special-case redirection to a single destination. */
1590 else if (ndests
== 1)
1591 lower_try_finally_onedest (state
, &this_tf
);
1592 else if (decide_copy_try_finally (ndests
, gimple_try_cleanup (tp
)))
1593 lower_try_finally_copy (state
, &this_tf
);
1595 lower_try_finally_switch (state
, &this_tf
);
1597 /* If someone requested we add a label at the end of the transformed
1599 if (this_tf
.fallthru_label
)
1601 /* This must be reached only if ndests == 0. */
1602 gimple x
= gimple_build_label (this_tf
.fallthru_label
);
1603 gimple_seq_add_stmt (&this_tf
.top_p_seq
, x
);
1606 VEC_free (tree
, heap
, this_tf
.dest_array
);
1607 if (this_tf
.goto_queue
)
1608 free (this_tf
.goto_queue
);
1609 if (this_tf
.goto_queue_map
)
1610 pointer_map_destroy (this_tf
.goto_queue_map
);
1612 return this_tf
.top_p_seq
;
1615 /* A subroutine of lower_eh_constructs_1. Lower a GIMPLE_TRY_CATCH with a
1616 list of GIMPLE_CATCH to a sequence of labels and blocks, plus the
1617 exception region trees that records all the magic. */
1620 lower_catch (struct leh_state
*state
, gimple tp
)
1622 eh_region try_region
;
1623 struct leh_state this_state
;
1624 gimple_stmt_iterator gsi
;
1628 location_t try_catch_loc
= gimple_location (tp
);
1630 try_region
= gen_eh_region_try (state
->cur_region
);
1632 this_state
= *state
;
1633 this_state
.cur_region
= try_region
;
1635 lower_eh_constructs_1 (&this_state
, gimple_try_eval (tp
));
1637 if (!bitmap_bit_p (eh_region_may_contain_throw
, try_region
->index
))
1638 return gimple_try_eval (tp
);
1641 emit_eh_dispatch (&new_seq
, try_region
);
1642 emit_resx (&new_seq
, try_region
);
1644 this_state
.cur_region
= state
->cur_region
;
1645 this_state
.ehp_region
= try_region
;
1648 for (gsi
= gsi_start (gimple_try_cleanup (tp
));
1656 gcatch
= gsi_stmt (gsi
);
1657 c
= gen_eh_region_catch (try_region
, gimple_catch_types (gcatch
));
1659 handler
= gimple_catch_handler (gcatch
);
1660 lower_eh_constructs_1 (&this_state
, handler
);
1662 c
->label
= create_artificial_label (UNKNOWN_LOCATION
);
1663 x
= gimple_build_label (c
->label
);
1664 gimple_seq_add_stmt (&new_seq
, x
);
1666 gimple_seq_add_seq (&new_seq
, handler
);
1668 if (gimple_seq_may_fallthru (new_seq
))
1671 out_label
= create_artificial_label (try_catch_loc
);
1673 x
= gimple_build_goto (out_label
);
1674 gimple_seq_add_stmt (&new_seq
, x
);
1678 gimple_try_set_cleanup (tp
, new_seq
);
1680 return frob_into_branch_around (tp
, try_region
, out_label
);
1683 /* A subroutine of lower_eh_constructs_1. Lower a GIMPLE_TRY with a
1684 GIMPLE_EH_FILTER to a sequence of labels and blocks, plus the exception
1685 region trees that record all the magic. */
1688 lower_eh_filter (struct leh_state
*state
, gimple tp
)
1690 struct leh_state this_state
;
1691 eh_region this_region
;
1695 inner
= gimple_seq_first_stmt (gimple_try_cleanup (tp
));
1697 this_region
= gen_eh_region_allowed (state
->cur_region
,
1698 gimple_eh_filter_types (inner
));
1699 this_state
= *state
;
1700 this_state
.cur_region
= this_region
;
1702 lower_eh_constructs_1 (&this_state
, gimple_try_eval (tp
));
1704 if (!bitmap_bit_p (eh_region_may_contain_throw
, this_region
->index
))
1705 return gimple_try_eval (tp
);
1708 this_state
.cur_region
= state
->cur_region
;
1709 this_state
.ehp_region
= this_region
;
1711 emit_eh_dispatch (&new_seq
, this_region
);
1712 emit_resx (&new_seq
, this_region
);
1714 this_region
->u
.allowed
.label
= create_artificial_label (UNKNOWN_LOCATION
);
1715 x
= gimple_build_label (this_region
->u
.allowed
.label
);
1716 gimple_seq_add_stmt (&new_seq
, x
);
1718 lower_eh_constructs_1 (&this_state
, gimple_eh_filter_failure (inner
));
1719 gimple_seq_add_seq (&new_seq
, gimple_eh_filter_failure (inner
));
1721 gimple_try_set_cleanup (tp
, new_seq
);
1723 return frob_into_branch_around (tp
, this_region
, NULL
);
1726 /* A subroutine of lower_eh_constructs_1. Lower a GIMPLE_TRY with
1727 an GIMPLE_EH_MUST_NOT_THROW to a sequence of labels and blocks,
1728 plus the exception region trees that record all the magic. */
1731 lower_eh_must_not_throw (struct leh_state
*state
, gimple tp
)
1733 struct leh_state this_state
;
1734 eh_region this_region
;
1737 inner
= gimple_seq_first_stmt (gimple_try_cleanup (tp
));
1739 this_region
= gen_eh_region_must_not_throw (state
->cur_region
);
1740 this_region
->u
.must_not_throw
.failure_decl
1741 = gimple_eh_must_not_throw_fndecl (inner
);
1742 this_region
->u
.must_not_throw
.failure_loc
= gimple_location (tp
);
1744 /* In order to get mangling applied to this decl, we must mark it
1745 used now. Otherwise, pass_ipa_free_lang_data won't think it
1747 TREE_USED (this_region
->u
.must_not_throw
.failure_decl
) = 1;
1749 this_state
= *state
;
1750 this_state
.cur_region
= this_region
;
1752 lower_eh_constructs_1 (&this_state
, gimple_try_eval (tp
));
1754 return gimple_try_eval (tp
);
1757 /* Implement a cleanup expression. This is similar to try-finally,
1758 except that we only execute the cleanup block for exception edges. */
1761 lower_cleanup (struct leh_state
*state
, gimple tp
)
1763 struct leh_state this_state
;
1764 eh_region this_region
;
1765 struct leh_tf_state fake_tf
;
1768 /* If not using eh, then exception-only cleanups are no-ops. */
1769 if (!flag_exceptions
)
1771 result
= gimple_try_eval (tp
);
1772 lower_eh_constructs_1 (state
, result
);
1776 this_region
= gen_eh_region_cleanup (state
->cur_region
);
1777 this_state
= *state
;
1778 this_state
.cur_region
= this_region
;
1780 lower_eh_constructs_1 (&this_state
, gimple_try_eval (tp
));
1782 if (!bitmap_bit_p (eh_region_may_contain_throw
, this_region
->index
))
1783 return gimple_try_eval (tp
);
1785 /* Build enough of a try-finally state so that we can reuse
1786 honor_protect_cleanup_actions. */
1787 memset (&fake_tf
, 0, sizeof (fake_tf
));
1788 fake_tf
.top_p
= fake_tf
.try_finally_expr
= tp
;
1789 fake_tf
.outer
= state
;
1790 fake_tf
.region
= this_region
;
1791 fake_tf
.may_fallthru
= gimple_seq_may_fallthru (gimple_try_eval (tp
));
1792 fake_tf
.may_throw
= true;
1794 honor_protect_cleanup_actions (state
, NULL
, &fake_tf
);
1796 if (fake_tf
.may_throw
)
1798 /* In this case honor_protect_cleanup_actions had nothing to do,
1799 and we should process this normally. */
1800 lower_eh_constructs_1 (state
, gimple_try_cleanup (tp
));
1801 result
= frob_into_branch_around (tp
, this_region
,
1802 fake_tf
.fallthru_label
);
1806 /* In this case honor_protect_cleanup_actions did nearly all of
1807 the work. All we have left is to append the fallthru_label. */
1809 result
= gimple_try_eval (tp
);
1810 if (fake_tf
.fallthru_label
)
1812 gimple x
= gimple_build_label (fake_tf
.fallthru_label
);
1813 gimple_seq_add_stmt (&result
, x
);
1819 /* Main loop for lowering eh constructs. Also moves gsi to the next
1823 lower_eh_constructs_2 (struct leh_state
*state
, gimple_stmt_iterator
*gsi
)
1827 gimple stmt
= gsi_stmt (*gsi
);
1829 switch (gimple_code (stmt
))
1833 tree fndecl
= gimple_call_fndecl (stmt
);
1836 if (fndecl
&& DECL_BUILT_IN_CLASS (fndecl
) == BUILT_IN_NORMAL
)
1837 switch (DECL_FUNCTION_CODE (fndecl
))
1839 case BUILT_IN_EH_POINTER
:
1840 /* The front end may have generated a call to
1841 __builtin_eh_pointer (0) within a catch region. Replace
1842 this zero argument with the current catch region number. */
1843 if (state
->ehp_region
)
1845 tree nr
= build_int_cst (NULL
, state
->ehp_region
->index
);
1846 gimple_call_set_arg (stmt
, 0, nr
);
1850 /* The user has dome something silly. Remove it. */
1851 rhs
= build_int_cst (ptr_type_node
, 0);
1856 case BUILT_IN_EH_FILTER
:
1857 /* ??? This should never appear, but since it's a builtin it
1858 is accessible to abuse by users. Just remove it and
1859 replace the use with the arbitrary value zero. */
1860 rhs
= build_int_cst (TREE_TYPE (TREE_TYPE (fndecl
)), 0);
1862 lhs
= gimple_call_lhs (stmt
);
1863 x
= gimple_build_assign (lhs
, rhs
);
1864 gsi_insert_before (gsi
, x
, GSI_SAME_STMT
);
1867 case BUILT_IN_EH_COPY_VALUES
:
1868 /* Likewise this should not appear. Remove it. */
1869 gsi_remove (gsi
, true);
1879 /* If the stmt can throw use a new temporary for the assignment
1880 to a LHS. This makes sure the old value of the LHS is
1881 available on the EH edge. */
1882 if (stmt_could_throw_p (stmt
)
1883 && gimple_has_lhs (stmt
)
1884 && !tree_could_throw_p (gimple_get_lhs (stmt
))
1885 && is_gimple_reg_type (TREE_TYPE (gimple_get_lhs (stmt
))))
1887 tree lhs
= gimple_get_lhs (stmt
);
1888 tree tmp
= create_tmp_var (TREE_TYPE (lhs
), NULL
);
1889 gimple s
= gimple_build_assign (lhs
, tmp
);
1890 gimple_set_location (s
, gimple_location (stmt
));
1891 gimple_set_block (s
, gimple_block (stmt
));
1892 gimple_set_lhs (stmt
, tmp
);
1893 if (TREE_CODE (TREE_TYPE (tmp
)) == COMPLEX_TYPE
1894 || TREE_CODE (TREE_TYPE (tmp
)) == VECTOR_TYPE
)
1895 DECL_GIMPLE_REG_P (tmp
) = 1;
1896 gsi_insert_after (gsi
, s
, GSI_SAME_STMT
);
1898 /* Look for things that can throw exceptions, and record them. */
1899 if (state
->cur_region
&& stmt_could_throw_p (stmt
))
1901 record_stmt_eh_region (state
->cur_region
, stmt
);
1902 note_eh_region_may_contain_throw (state
->cur_region
);
1909 maybe_record_in_goto_queue (state
, stmt
);
1913 verify_norecord_switch_expr (state
, stmt
);
1917 if (gimple_try_kind (stmt
) == GIMPLE_TRY_FINALLY
)
1918 replace
= lower_try_finally (state
, stmt
);
1921 x
= gimple_seq_first_stmt (gimple_try_cleanup (stmt
));
1924 replace
= gimple_try_eval (stmt
);
1925 lower_eh_constructs_1 (state
, replace
);
1928 switch (gimple_code (x
))
1931 replace
= lower_catch (state
, stmt
);
1933 case GIMPLE_EH_FILTER
:
1934 replace
= lower_eh_filter (state
, stmt
);
1936 case GIMPLE_EH_MUST_NOT_THROW
:
1937 replace
= lower_eh_must_not_throw (state
, stmt
);
1940 replace
= lower_cleanup (state
, stmt
);
1945 /* Remove the old stmt and insert the transformed sequence
1947 gsi_insert_seq_before (gsi
, replace
, GSI_SAME_STMT
);
1948 gsi_remove (gsi
, true);
1950 /* Return since we don't want gsi_next () */
1954 /* A type, a decl, or some kind of statement that we're not
1955 interested in. Don't walk them. */
1962 /* A helper to unwrap a gimple_seq and feed stmts to lower_eh_constructs_2. */
1965 lower_eh_constructs_1 (struct leh_state
*state
, gimple_seq seq
)
1967 gimple_stmt_iterator gsi
;
1968 for (gsi
= gsi_start (seq
); !gsi_end_p (gsi
);)
1969 lower_eh_constructs_2 (state
, &gsi
);
1973 lower_eh_constructs (void)
1975 struct leh_state null_state
;
1978 bodyp
= gimple_body (current_function_decl
);
1982 finally_tree
= htab_create (31, struct_ptr_hash
, struct_ptr_eq
, free
);
1983 eh_region_may_contain_throw
= BITMAP_ALLOC (NULL
);
1984 memset (&null_state
, 0, sizeof (null_state
));
1986 collect_finally_tree_1 (bodyp
, NULL
);
1987 lower_eh_constructs_1 (&null_state
, bodyp
);
1989 /* We assume there's a return statement, or something, at the end of
1990 the function, and thus ploping the EH sequence afterward won't
1992 gcc_assert (!gimple_seq_may_fallthru (bodyp
));
1993 gimple_seq_add_seq (&bodyp
, eh_seq
);
1995 /* We assume that since BODYP already existed, adding EH_SEQ to it
1996 didn't change its value, and we don't have to re-set the function. */
1997 gcc_assert (bodyp
== gimple_body (current_function_decl
));
1999 htab_delete (finally_tree
);
2000 BITMAP_FREE (eh_region_may_contain_throw
);
2003 /* If this function needs a language specific EH personality routine
2004 and the frontend didn't already set one do so now. */
2005 if (function_needs_eh_personality (cfun
) == eh_personality_lang
2006 && !DECL_FUNCTION_PERSONALITY (current_function_decl
))
2007 DECL_FUNCTION_PERSONALITY (current_function_decl
)
2008 = lang_hooks
.eh_personality ();
2013 struct gimple_opt_pass pass_lower_eh
=
2019 lower_eh_constructs
, /* execute */
2022 0, /* static_pass_number */
2023 TV_TREE_EH
, /* tv_id */
2024 PROP_gimple_lcf
, /* properties_required */
2025 PROP_gimple_leh
, /* properties_provided */
2026 0, /* properties_destroyed */
2027 0, /* todo_flags_start */
2028 TODO_dump_func
/* todo_flags_finish */
2032 /* Create the multiple edges from an EH_DISPATCH statement to all of
2033 the possible handlers for its EH region. Return true if there's
2034 no fallthru edge; false if there is. */
2037 make_eh_dispatch_edges (gimple stmt
)
2041 basic_block src
, dst
;
2043 r
= get_eh_region_from_number (gimple_eh_dispatch_region (stmt
));
2044 src
= gimple_bb (stmt
);
2049 for (c
= r
->u
.eh_try
.first_catch
; c
; c
= c
->next_catch
)
2051 dst
= label_to_block (c
->label
);
2052 make_edge (src
, dst
, 0);
2054 /* A catch-all handler doesn't have a fallthru. */
2055 if (c
->type_list
== NULL
)
2060 case ERT_ALLOWED_EXCEPTIONS
:
2061 dst
= label_to_block (r
->u
.allowed
.label
);
2062 make_edge (src
, dst
, 0);
2072 /* Create the single EH edge from STMT to its nearest landing pad,
2073 if there is such a landing pad within the current function. */
2076 make_eh_edges (gimple stmt
)
2078 basic_block src
, dst
;
2082 lp_nr
= lookup_stmt_eh_lp (stmt
);
2086 lp
= get_eh_landing_pad_from_number (lp_nr
);
2087 gcc_assert (lp
!= NULL
);
2089 src
= gimple_bb (stmt
);
2090 dst
= label_to_block (lp
->post_landing_pad
);
2091 make_edge (src
, dst
, EDGE_EH
);
2094 /* Do the work in redirecting EDGE_IN to NEW_BB within the EH region tree;
2095 do not actually perform the final edge redirection.
2097 CHANGE_REGION is true when we're being called from cleanup_empty_eh and
2098 we intend to change the destination EH region as well; this means
2099 EH_LANDING_PAD_NR must already be set on the destination block label.
2100 If false, we're being called from generic cfg manipulation code and we
2101 should preserve our place within the region tree. */
2104 redirect_eh_edge_1 (edge edge_in
, basic_block new_bb
, bool change_region
)
2106 eh_landing_pad old_lp
, new_lp
;
2109 int old_lp_nr
, new_lp_nr
;
2110 tree old_label
, new_label
;
2114 old_bb
= edge_in
->dest
;
2115 old_label
= gimple_block_label (old_bb
);
2116 old_lp_nr
= EH_LANDING_PAD_NR (old_label
);
2117 gcc_assert (old_lp_nr
> 0);
2118 old_lp
= get_eh_landing_pad_from_number (old_lp_nr
);
2120 throw_stmt
= last_stmt (edge_in
->src
);
2121 gcc_assert (lookup_stmt_eh_lp (throw_stmt
) == old_lp_nr
);
2123 new_label
= gimple_block_label (new_bb
);
2125 /* Look for an existing region that might be using NEW_BB already. */
2126 new_lp_nr
= EH_LANDING_PAD_NR (new_label
);
2129 new_lp
= get_eh_landing_pad_from_number (new_lp_nr
);
2130 gcc_assert (new_lp
);
2132 /* Unless CHANGE_REGION is true, the new and old landing pad
2133 had better be associated with the same EH region. */
2134 gcc_assert (change_region
|| new_lp
->region
== old_lp
->region
);
2139 gcc_assert (!change_region
);
2142 /* Notice when we redirect the last EH edge away from OLD_BB. */
2143 FOR_EACH_EDGE (e
, ei
, old_bb
->preds
)
2144 if (e
!= edge_in
&& (e
->flags
& EDGE_EH
))
2149 /* NEW_LP already exists. If there are still edges into OLD_LP,
2150 there's nothing to do with the EH tree. If there are no more
2151 edges into OLD_LP, then we want to remove OLD_LP as it is unused.
2152 If CHANGE_REGION is true, then our caller is expecting to remove
2154 if (e
== NULL
&& !change_region
)
2155 remove_eh_landing_pad (old_lp
);
2159 /* No correct landing pad exists. If there are no more edges
2160 into OLD_LP, then we can simply re-use the existing landing pad.
2161 Otherwise, we have to create a new landing pad. */
2164 EH_LANDING_PAD_NR (old_lp
->post_landing_pad
) = 0;
2168 new_lp
= gen_eh_landing_pad (old_lp
->region
);
2169 new_lp
->post_landing_pad
= new_label
;
2170 EH_LANDING_PAD_NR (new_label
) = new_lp
->index
;
2173 /* Maybe move the throwing statement to the new region. */
2174 if (old_lp
!= new_lp
)
2176 remove_stmt_from_eh_lp (throw_stmt
);
2177 add_stmt_to_eh_lp (throw_stmt
, new_lp
->index
);
2181 /* Redirect EH edge E to NEW_BB. */
2184 redirect_eh_edge (edge edge_in
, basic_block new_bb
)
2186 redirect_eh_edge_1 (edge_in
, new_bb
, false);
2187 return ssa_redirect_edge (edge_in
, new_bb
);
2190 /* This is a subroutine of gimple_redirect_edge_and_branch. Update the
2191 labels for redirecting a non-fallthru EH_DISPATCH edge E to NEW_BB.
2192 The actual edge update will happen in the caller. */
2195 redirect_eh_dispatch_edge (gimple stmt
, edge e
, basic_block new_bb
)
2197 tree new_lab
= gimple_block_label (new_bb
);
2198 bool any_changed
= false;
2203 r
= get_eh_region_from_number (gimple_eh_dispatch_region (stmt
));
2207 for (c
= r
->u
.eh_try
.first_catch
; c
; c
= c
->next_catch
)
2209 old_bb
= label_to_block (c
->label
);
2210 if (old_bb
== e
->dest
)
2218 case ERT_ALLOWED_EXCEPTIONS
:
2219 old_bb
= label_to_block (r
->u
.allowed
.label
);
2220 gcc_assert (old_bb
== e
->dest
);
2221 r
->u
.allowed
.label
= new_lab
;
2229 gcc_assert (any_changed
);
2232 /* Helper function for operation_could_trap_p and stmt_could_throw_p. */
2235 operation_could_trap_helper_p (enum tree_code op
,
2246 case TRUNC_DIV_EXPR
:
2248 case FLOOR_DIV_EXPR
:
2249 case ROUND_DIV_EXPR
:
2250 case EXACT_DIV_EXPR
:
2252 case FLOOR_MOD_EXPR
:
2253 case ROUND_MOD_EXPR
:
2254 case TRUNC_MOD_EXPR
:
2256 if (honor_snans
|| honor_trapv
)
2259 return flag_trapping_math
;
2260 if (!TREE_CONSTANT (divisor
) || integer_zerop (divisor
))
2269 /* Some floating point comparisons may trap. */
2274 case UNORDERED_EXPR
:
2284 case FIX_TRUNC_EXPR
:
2285 /* Conversion of floating point might trap. */
2291 /* These operations don't trap with floating point. */
2299 /* Any floating arithmetic may trap. */
2300 if (fp_operation
&& flag_trapping_math
)
2307 /* Any floating arithmetic may trap. */
2308 if (fp_operation
&& flag_trapping_math
)
2316 /* Return true if operation OP may trap. FP_OPERATION is true if OP is applied
2317 on floating-point values. HONOR_TRAPV is true if OP is applied on integer
2318 type operands that may trap. If OP is a division operator, DIVISOR contains
2319 the value of the divisor. */
2322 operation_could_trap_p (enum tree_code op
, bool fp_operation
, bool honor_trapv
,
2325 bool honor_nans
= (fp_operation
&& flag_trapping_math
2326 && !flag_finite_math_only
);
2327 bool honor_snans
= fp_operation
&& flag_signaling_nans
!= 0;
2330 if (TREE_CODE_CLASS (op
) != tcc_comparison
2331 && TREE_CODE_CLASS (op
) != tcc_unary
2332 && TREE_CODE_CLASS (op
) != tcc_binary
)
2335 return operation_could_trap_helper_p (op
, fp_operation
, honor_trapv
,
2336 honor_nans
, honor_snans
, divisor
,
2340 /* Return true if EXPR can trap, as in dereferencing an invalid pointer
2341 location or floating point arithmetic. C.f. the rtl version, may_trap_p.
2342 This routine expects only GIMPLE lhs or rhs input. */
2345 tree_could_trap_p (tree expr
)
2347 enum tree_code code
;
2348 bool fp_operation
= false;
2349 bool honor_trapv
= false;
2350 tree t
, base
, div
= NULL_TREE
;
2355 code
= TREE_CODE (expr
);
2356 t
= TREE_TYPE (expr
);
2360 if (COMPARISON_CLASS_P (expr
))
2361 fp_operation
= FLOAT_TYPE_P (TREE_TYPE (TREE_OPERAND (expr
, 0)));
2363 fp_operation
= FLOAT_TYPE_P (t
);
2364 honor_trapv
= INTEGRAL_TYPE_P (t
) && TYPE_OVERFLOW_TRAPS (t
);
2367 if (TREE_CODE_CLASS (code
) == tcc_binary
)
2368 div
= TREE_OPERAND (expr
, 1);
2369 if (operation_could_trap_p (code
, fp_operation
, honor_trapv
, div
))
2375 case TARGET_MEM_REF
:
2376 /* For TARGET_MEM_REFs use the information based on the original
2378 expr
= TMR_ORIGINAL (expr
);
2379 code
= TREE_CODE (expr
);
2386 case VIEW_CONVERT_EXPR
:
2387 case WITH_SIZE_EXPR
:
2388 expr
= TREE_OPERAND (expr
, 0);
2389 code
= TREE_CODE (expr
);
2392 case ARRAY_RANGE_REF
:
2393 base
= TREE_OPERAND (expr
, 0);
2394 if (tree_could_trap_p (base
))
2396 if (TREE_THIS_NOTRAP (expr
))
2398 return !range_in_array_bounds_p (expr
);
2401 base
= TREE_OPERAND (expr
, 0);
2402 if (tree_could_trap_p (base
))
2404 if (TREE_THIS_NOTRAP (expr
))
2406 return !in_array_bounds_p (expr
);
2409 case ALIGN_INDIRECT_REF
:
2410 case MISALIGNED_INDIRECT_REF
:
2411 return !TREE_THIS_NOTRAP (expr
);
2414 return TREE_THIS_VOLATILE (expr
);
2417 t
= get_callee_fndecl (expr
);
2418 /* Assume that calls to weak functions may trap. */
2419 if (!t
|| !DECL_P (t
) || DECL_WEAK (t
))
2429 /* Helper for stmt_could_throw_p. Return true if STMT (assumed to be a
2430 an assignment or a conditional) may throw. */
2433 stmt_could_throw_1_p (gimple stmt
)
2435 enum tree_code code
= gimple_expr_code (stmt
);
2436 bool honor_nans
= false;
2437 bool honor_snans
= false;
2438 bool fp_operation
= false;
2439 bool honor_trapv
= false;
2444 if (TREE_CODE_CLASS (code
) == tcc_comparison
2445 || TREE_CODE_CLASS (code
) == tcc_unary
2446 || TREE_CODE_CLASS (code
) == tcc_binary
)
2448 t
= gimple_expr_type (stmt
);
2449 fp_operation
= FLOAT_TYPE_P (t
);
2452 honor_nans
= flag_trapping_math
&& !flag_finite_math_only
;
2453 honor_snans
= flag_signaling_nans
!= 0;
2455 else if (INTEGRAL_TYPE_P (t
) && TYPE_OVERFLOW_TRAPS (t
))
2459 /* Check if the main expression may trap. */
2460 t
= is_gimple_assign (stmt
) ? gimple_assign_rhs2 (stmt
) : NULL
;
2461 ret
= operation_could_trap_helper_p (code
, fp_operation
, honor_trapv
,
2462 honor_nans
, honor_snans
, t
,
2467 /* If the expression does not trap, see if any of the individual operands may
2469 for (i
= 0; i
< gimple_num_ops (stmt
); i
++)
2470 if (tree_could_trap_p (gimple_op (stmt
, i
)))
2477 /* Return true if statement STMT could throw an exception. */
2480 stmt_could_throw_p (gimple stmt
)
2482 if (!flag_exceptions
)
2485 /* The only statements that can throw an exception are assignments,
2486 conditionals, calls, resx, and asms. */
2487 switch (gimple_code (stmt
))
2493 return !gimple_call_nothrow_p (stmt
);
2497 if (!flag_non_call_exceptions
)
2499 return stmt_could_throw_1_p (stmt
);
2502 if (!flag_non_call_exceptions
)
2504 return gimple_asm_volatile_p (stmt
);
2512 /* Return true if expression T could throw an exception. */
2515 tree_could_throw_p (tree t
)
2517 if (!flag_exceptions
)
2519 if (TREE_CODE (t
) == MODIFY_EXPR
)
2521 if (flag_non_call_exceptions
2522 && tree_could_trap_p (TREE_OPERAND (t
, 0)))
2524 t
= TREE_OPERAND (t
, 1);
2527 if (TREE_CODE (t
) == WITH_SIZE_EXPR
)
2528 t
= TREE_OPERAND (t
, 0);
2529 if (TREE_CODE (t
) == CALL_EXPR
)
2530 return (call_expr_flags (t
) & ECF_NOTHROW
) == 0;
2531 if (flag_non_call_exceptions
)
2532 return tree_could_trap_p (t
);
2536 /* Return true if STMT can throw an exception that is not caught within
2537 the current function (CFUN). */
2540 stmt_can_throw_external (gimple stmt
)
2544 if (!stmt_could_throw_p (stmt
))
2547 lp_nr
= lookup_stmt_eh_lp (stmt
);
2551 /* Return true if STMT can throw an exception that is caught within
2552 the current function (CFUN). */
2555 stmt_can_throw_internal (gimple stmt
)
2559 if (!stmt_could_throw_p (stmt
))
2562 lp_nr
= lookup_stmt_eh_lp (stmt
);
2566 /* Given a statement STMT in IFUN, if STMT can no longer throw, then
2567 remove any entry it might have from the EH table. Return true if
2568 any change was made. */
2571 maybe_clean_eh_stmt_fn (struct function
*ifun
, gimple stmt
)
2573 if (stmt_could_throw_p (stmt
))
2575 return remove_stmt_from_eh_lp_fn (ifun
, stmt
);
2578 /* Likewise, but always use the current function. */
2581 maybe_clean_eh_stmt (gimple stmt
)
2583 return maybe_clean_eh_stmt_fn (cfun
, stmt
);
2586 /* Given a statement OLD_STMT and a new statement NEW_STMT that has replaced
2587 OLD_STMT in the function, remove OLD_STMT from the EH table and put NEW_STMT
2588 in the table if it should be in there. Return TRUE if a replacement was
2589 done that my require an EH edge purge. */
2592 maybe_clean_or_replace_eh_stmt (gimple old_stmt
, gimple new_stmt
)
2594 int lp_nr
= lookup_stmt_eh_lp (old_stmt
);
2598 bool new_stmt_could_throw
= stmt_could_throw_p (new_stmt
);
2600 if (new_stmt
== old_stmt
&& new_stmt_could_throw
)
2603 remove_stmt_from_eh_lp (old_stmt
);
2604 if (new_stmt_could_throw
)
2606 add_stmt_to_eh_lp (new_stmt
, lp_nr
);
2616 /* Given a statement OLD_STMT in OLD_FUN and a duplicate statment NEW_STMT
2617 in NEW_FUN, copy the EH table data from OLD_STMT to NEW_STMT. The MAP
2618 operand is the return value of duplicate_eh_regions. */
2621 maybe_duplicate_eh_stmt_fn (struct function
*new_fun
, gimple new_stmt
,
2622 struct function
*old_fun
, gimple old_stmt
,
2623 struct pointer_map_t
*map
, int default_lp_nr
)
2625 int old_lp_nr
, new_lp_nr
;
2628 if (!stmt_could_throw_p (new_stmt
))
2631 old_lp_nr
= lookup_stmt_eh_lp_fn (old_fun
, old_stmt
);
2634 if (default_lp_nr
== 0)
2636 new_lp_nr
= default_lp_nr
;
2638 else if (old_lp_nr
> 0)
2640 eh_landing_pad old_lp
, new_lp
;
2642 old_lp
= VEC_index (eh_landing_pad
, old_fun
->eh
->lp_array
, old_lp_nr
);
2643 slot
= pointer_map_contains (map
, old_lp
);
2644 new_lp
= (eh_landing_pad
) *slot
;
2645 new_lp_nr
= new_lp
->index
;
2649 eh_region old_r
, new_r
;
2651 old_r
= VEC_index (eh_region
, old_fun
->eh
->region_array
, -old_lp_nr
);
2652 slot
= pointer_map_contains (map
, old_r
);
2653 new_r
= (eh_region
) *slot
;
2654 new_lp_nr
= -new_r
->index
;
2657 add_stmt_to_eh_lp_fn (new_fun
, new_stmt
, new_lp_nr
);
2661 /* Similar, but both OLD_STMT and NEW_STMT are within the current function,
2662 and thus no remapping is required. */
2665 maybe_duplicate_eh_stmt (gimple new_stmt
, gimple old_stmt
)
2669 if (!stmt_could_throw_p (new_stmt
))
2672 lp_nr
= lookup_stmt_eh_lp (old_stmt
);
2676 add_stmt_to_eh_lp (new_stmt
, lp_nr
);
2680 /* Returns TRUE if oneh and twoh are exception handlers (gimple_try_cleanup of
2681 GIMPLE_TRY) that are similar enough to be considered the same. Currently
2682 this only handles handlers consisting of a single call, as that's the
2683 important case for C++: a destructor call for a particular object showing
2684 up in multiple handlers. */
2687 same_handler_p (gimple_seq oneh
, gimple_seq twoh
)
2689 gimple_stmt_iterator gsi
;
2693 gsi
= gsi_start (oneh
);
2694 if (!gsi_one_before_end_p (gsi
))
2696 ones
= gsi_stmt (gsi
);
2698 gsi
= gsi_start (twoh
);
2699 if (!gsi_one_before_end_p (gsi
))
2701 twos
= gsi_stmt (gsi
);
2703 if (!is_gimple_call (ones
)
2704 || !is_gimple_call (twos
)
2705 || gimple_call_lhs (ones
)
2706 || gimple_call_lhs (twos
)
2707 || gimple_call_chain (ones
)
2708 || gimple_call_chain (twos
)
2709 || !operand_equal_p (gimple_call_fn (ones
), gimple_call_fn (twos
), 0)
2710 || gimple_call_num_args (ones
) != gimple_call_num_args (twos
))
2713 for (ai
= 0; ai
< gimple_call_num_args (ones
); ++ai
)
2714 if (!operand_equal_p (gimple_call_arg (ones
, ai
),
2715 gimple_call_arg (twos
, ai
), 0))
2722 try { A() } finally { try { ~B() } catch { ~A() } }
2723 try { ... } finally { ~A() }
2725 try { A() } catch { ~B() }
2726 try { ~B() ... } finally { ~A() }
2728 This occurs frequently in C++, where A is a local variable and B is a
2729 temporary used in the initializer for A. */
2732 optimize_double_finally (gimple one
, gimple two
)
2735 gimple_stmt_iterator gsi
;
2737 gsi
= gsi_start (gimple_try_cleanup (one
));
2738 if (!gsi_one_before_end_p (gsi
))
2741 oneh
= gsi_stmt (gsi
);
2742 if (gimple_code (oneh
) != GIMPLE_TRY
2743 || gimple_try_kind (oneh
) != GIMPLE_TRY_CATCH
)
2746 if (same_handler_p (gimple_try_cleanup (oneh
), gimple_try_cleanup (two
)))
2748 gimple_seq seq
= gimple_try_eval (oneh
);
2750 gimple_try_set_cleanup (one
, seq
);
2751 gimple_try_set_kind (one
, GIMPLE_TRY_CATCH
);
2752 seq
= copy_gimple_seq_and_replace_locals (seq
);
2753 gimple_seq_add_seq (&seq
, gimple_try_eval (two
));
2754 gimple_try_set_eval (two
, seq
);
2758 /* Perform EH refactoring optimizations that are simpler to do when code
2759 flow has been lowered but EH structures haven't. */
2762 refactor_eh_r (gimple_seq seq
)
2764 gimple_stmt_iterator gsi
;
2769 gsi
= gsi_start (seq
);
2773 if (gsi_end_p (gsi
))
2776 two
= gsi_stmt (gsi
);
2779 && gimple_code (one
) == GIMPLE_TRY
2780 && gimple_code (two
) == GIMPLE_TRY
2781 && gimple_try_kind (one
) == GIMPLE_TRY_FINALLY
2782 && gimple_try_kind (two
) == GIMPLE_TRY_FINALLY
)
2783 optimize_double_finally (one
, two
);
2785 switch (gimple_code (one
))
2788 refactor_eh_r (gimple_try_eval (one
));
2789 refactor_eh_r (gimple_try_cleanup (one
));
2792 refactor_eh_r (gimple_catch_handler (one
));
2794 case GIMPLE_EH_FILTER
:
2795 refactor_eh_r (gimple_eh_filter_failure (one
));
2810 refactor_eh_r (gimple_body (current_function_decl
));
2815 gate_refactor_eh (void)
2817 return flag_exceptions
!= 0;
2820 struct gimple_opt_pass pass_refactor_eh
=
2825 gate_refactor_eh
, /* gate */
2826 refactor_eh
, /* execute */
2829 0, /* static_pass_number */
2830 TV_TREE_EH
, /* tv_id */
2831 PROP_gimple_lcf
, /* properties_required */
2832 0, /* properties_provided */
2833 0, /* properties_destroyed */
2834 0, /* todo_flags_start */
2835 TODO_dump_func
/* todo_flags_finish */
2839 /* At the end of gimple optimization, we can lower RESX. */
2842 lower_resx (basic_block bb
, gimple stmt
, struct pointer_map_t
*mnt_map
)
2845 eh_region src_r
, dst_r
;
2846 gimple_stmt_iterator gsi
;
2851 lp_nr
= lookup_stmt_eh_lp (stmt
);
2853 dst_r
= get_eh_region_from_lp_number (lp_nr
);
2857 src_r
= get_eh_region_from_number (gimple_resx_region (stmt
));
2858 gsi
= gsi_last_bb (bb
);
2862 /* We can wind up with no source region when pass_cleanup_eh shows
2863 that there are no entries into an eh region and deletes it, but
2864 then the block that contains the resx isn't removed. This can
2865 happen without optimization when the switch statement created by
2866 lower_try_finally_switch isn't simplified to remove the eh case.
2868 Resolve this by expanding the resx node to an abort. */
2870 fn
= implicit_built_in_decls
[BUILT_IN_TRAP
];
2871 x
= gimple_build_call (fn
, 0);
2872 gsi_insert_before (&gsi
, x
, GSI_SAME_STMT
);
2874 while (EDGE_COUNT (bb
->succs
) > 0)
2875 remove_edge (EDGE_SUCC (bb
, 0));
2879 /* When we have a destination region, we resolve this by copying
2880 the excptr and filter values into place, and changing the edge
2881 to immediately after the landing pad. */
2890 /* We are resuming into a MUST_NOT_CALL region. Expand a call to
2891 the failure decl into a new block, if needed. */
2892 gcc_assert (dst_r
->type
== ERT_MUST_NOT_THROW
);
2894 slot
= pointer_map_contains (mnt_map
, dst_r
);
2897 gimple_stmt_iterator gsi2
;
2899 new_bb
= create_empty_bb (bb
);
2900 lab
= gimple_block_label (new_bb
);
2901 gsi2
= gsi_start_bb (new_bb
);
2903 fn
= dst_r
->u
.must_not_throw
.failure_decl
;
2904 x
= gimple_build_call (fn
, 0);
2905 gimple_set_location (x
, dst_r
->u
.must_not_throw
.failure_loc
);
2906 gsi_insert_after (&gsi2
, x
, GSI_CONTINUE_LINKING
);
2908 slot
= pointer_map_insert (mnt_map
, dst_r
);
2914 new_bb
= label_to_block (lab
);
2917 gcc_assert (EDGE_COUNT (bb
->succs
) == 0);
2918 e
= make_edge (bb
, new_bb
, EDGE_FALLTHRU
);
2919 e
->count
= bb
->count
;
2920 e
->probability
= REG_BR_PROB_BASE
;
2925 tree dst_nr
= build_int_cst (NULL
, dst_r
->index
);
2927 fn
= implicit_built_in_decls
[BUILT_IN_EH_COPY_VALUES
];
2928 src_nr
= build_int_cst (NULL
, src_r
->index
);
2929 x
= gimple_build_call (fn
, 2, dst_nr
, src_nr
);
2930 gsi_insert_before (&gsi
, x
, GSI_SAME_STMT
);
2932 /* Update the flags for the outgoing edge. */
2933 e
= single_succ_edge (bb
);
2934 gcc_assert (e
->flags
& EDGE_EH
);
2935 e
->flags
= (e
->flags
& ~EDGE_EH
) | EDGE_FALLTHRU
;
2937 /* If there are no more EH users of the landing pad, delete it. */
2938 FOR_EACH_EDGE (e
, ei
, e
->dest
->preds
)
2939 if (e
->flags
& EDGE_EH
)
2943 eh_landing_pad lp
= get_eh_landing_pad_from_number (lp_nr
);
2944 remove_eh_landing_pad (lp
);
2954 /* When we don't have a destination region, this exception escapes
2955 up the call chain. We resolve this by generating a call to the
2956 _Unwind_Resume library function. */
2958 /* The ARM EABI redefines _Unwind_Resume as __cxa_end_cleanup
2959 with no arguments for C++ and Java. Check for that. */
2960 if (src_r
->use_cxa_end_cleanup
)
2962 fn
= implicit_built_in_decls
[BUILT_IN_CXA_END_CLEANUP
];
2963 x
= gimple_build_call (fn
, 0);
2964 gsi_insert_before (&gsi
, x
, GSI_SAME_STMT
);
2968 fn
= implicit_built_in_decls
[BUILT_IN_EH_POINTER
];
2969 src_nr
= build_int_cst (NULL
, src_r
->index
);
2970 x
= gimple_build_call (fn
, 1, src_nr
);
2971 var
= create_tmp_var (ptr_type_node
, NULL
);
2972 var
= make_ssa_name (var
, x
);
2973 gimple_call_set_lhs (x
, var
);
2974 gsi_insert_before (&gsi
, x
, GSI_SAME_STMT
);
2976 fn
= implicit_built_in_decls
[BUILT_IN_UNWIND_RESUME
];
2977 x
= gimple_build_call (fn
, 1, var
);
2978 gsi_insert_before (&gsi
, x
, GSI_SAME_STMT
);
2981 gcc_assert (EDGE_COUNT (bb
->succs
) == 0);
2984 gsi_remove (&gsi
, true);
2990 execute_lower_resx (void)
2993 struct pointer_map_t
*mnt_map
;
2994 bool dominance_invalidated
= false;
2995 bool any_rewritten
= false;
2997 mnt_map
= pointer_map_create ();
3001 gimple last
= last_stmt (bb
);
3002 if (last
&& is_gimple_resx (last
))
3004 dominance_invalidated
|= lower_resx (bb
, last
, mnt_map
);
3005 any_rewritten
= true;
3009 pointer_map_destroy (mnt_map
);
3011 if (dominance_invalidated
)
3013 free_dominance_info (CDI_DOMINATORS
);
3014 free_dominance_info (CDI_POST_DOMINATORS
);
3017 return any_rewritten
? TODO_update_ssa_only_virtuals
: 0;
3021 gate_lower_resx (void)
3023 return flag_exceptions
!= 0;
3026 struct gimple_opt_pass pass_lower_resx
=
3031 gate_lower_resx
, /* gate */
3032 execute_lower_resx
, /* execute */
3035 0, /* static_pass_number */
3036 TV_TREE_EH
, /* tv_id */
3037 PROP_gimple_lcf
, /* properties_required */
3038 0, /* properties_provided */
3039 0, /* properties_destroyed */
3040 0, /* todo_flags_start */
3041 TODO_dump_func
| TODO_verify_flow
/* todo_flags_finish */
3046 /* At the end of inlining, we can lower EH_DISPATCH. */
3049 lower_eh_dispatch (basic_block src
, gimple stmt
)
3051 gimple_stmt_iterator gsi
;
3057 region_nr
= gimple_eh_dispatch_region (stmt
);
3058 r
= get_eh_region_from_number (region_nr
);
3060 gsi
= gsi_last_bb (src
);
3066 VEC (tree
, heap
) *labels
= NULL
;
3067 tree default_label
= NULL
;
3072 /* Collect the labels for a switch. Zero the post_landing_pad
3073 field becase we'll no longer have anything keeping these labels
3074 in existance and the optimizer will be free to merge these
3076 for (c
= r
->u
.eh_try
.first_catch
; c
; c
= c
->next_catch
)
3078 tree tp_node
, flt_node
, lab
= c
->label
;
3081 tp_node
= c
->type_list
;
3082 flt_node
= c
->filter_list
;
3084 if (tp_node
== NULL
)
3086 default_label
= lab
;
3091 tree t
= build3 (CASE_LABEL_EXPR
, void_type_node
,
3092 TREE_VALUE (flt_node
), NULL
, lab
);
3093 VEC_safe_push (tree
, heap
, labels
, t
);
3095 tp_node
= TREE_CHAIN (tp_node
);
3096 flt_node
= TREE_CHAIN (flt_node
);
3101 /* Clean up the edge flags. */
3102 FOR_EACH_EDGE (e
, ei
, src
->succs
)
3104 if (e
->flags
& EDGE_FALLTHRU
)
3106 /* If there was no catch-all, use the fallthru edge. */
3107 if (default_label
== NULL
)
3108 default_label
= gimple_block_label (e
->dest
);
3109 e
->flags
&= ~EDGE_FALLTHRU
;
3112 gcc_assert (default_label
!= NULL
);
3114 /* Don't generate a switch if there's only a default case.
3115 This is common in the form of try { A; } catch (...) { B; }. */
3118 e
= single_succ_edge (src
);
3119 e
->flags
|= EDGE_FALLTHRU
;
3123 fn
= implicit_built_in_decls
[BUILT_IN_EH_FILTER
];
3124 x
= gimple_build_call (fn
, 1, build_int_cst (NULL
, region_nr
));
3125 filter
= create_tmp_var (TREE_TYPE (TREE_TYPE (fn
)), NULL
);
3126 filter
= make_ssa_name (filter
, x
);
3127 gimple_call_set_lhs (x
, filter
);
3128 gsi_insert_before (&gsi
, x
, GSI_SAME_STMT
);
3130 /* Turn the default label into a default case. */
3131 default_label
= build3 (CASE_LABEL_EXPR
, void_type_node
,
3132 NULL
, NULL
, default_label
);
3133 sort_case_labels (labels
);
3135 x
= gimple_build_switch_vec (filter
, default_label
, labels
);
3136 gsi_insert_before (&gsi
, x
, GSI_SAME_STMT
);
3138 VEC_free (tree
, heap
, labels
);
3143 case ERT_ALLOWED_EXCEPTIONS
:
3145 edge b_e
= BRANCH_EDGE (src
);
3146 edge f_e
= FALLTHRU_EDGE (src
);
3148 fn
= implicit_built_in_decls
[BUILT_IN_EH_FILTER
];
3149 x
= gimple_build_call (fn
, 1, build_int_cst (NULL
, region_nr
));
3150 filter
= create_tmp_var (TREE_TYPE (TREE_TYPE (fn
)), NULL
);
3151 filter
= make_ssa_name (filter
, x
);
3152 gimple_call_set_lhs (x
, filter
);
3153 gsi_insert_before (&gsi
, x
, GSI_SAME_STMT
);
3155 r
->u
.allowed
.label
= NULL
;
3156 x
= gimple_build_cond (EQ_EXPR
, filter
,
3157 build_int_cst (TREE_TYPE (filter
),
3158 r
->u
.allowed
.filter
),
3159 NULL_TREE
, NULL_TREE
);
3160 gsi_insert_before (&gsi
, x
, GSI_SAME_STMT
);
3162 b_e
->flags
= b_e
->flags
| EDGE_TRUE_VALUE
;
3163 f_e
->flags
= (f_e
->flags
& ~EDGE_FALLTHRU
) | EDGE_FALSE_VALUE
;
3171 /* Replace the EH_DISPATCH with the SWITCH or COND generated above. */
3172 gsi_remove (&gsi
, true);
3176 execute_lower_eh_dispatch (void)
3179 bool any_rewritten
= false;
3181 assign_filter_values ();
3185 gimple last
= last_stmt (bb
);
3186 if (last
&& gimple_code (last
) == GIMPLE_EH_DISPATCH
)
3188 lower_eh_dispatch (bb
, last
);
3189 any_rewritten
= true;
3193 return any_rewritten
? TODO_update_ssa_only_virtuals
: 0;
3197 gate_lower_eh_dispatch (void)
3199 return cfun
->eh
->region_tree
!= NULL
;
3202 struct gimple_opt_pass pass_lower_eh_dispatch
=
3206 "ehdisp", /* name */
3207 gate_lower_eh_dispatch
, /* gate */
3208 execute_lower_eh_dispatch
, /* execute */
3211 0, /* static_pass_number */
3212 TV_TREE_EH
, /* tv_id */
3213 PROP_gimple_lcf
, /* properties_required */
3214 0, /* properties_provided */
3215 0, /* properties_destroyed */
3216 0, /* todo_flags_start */
3217 TODO_dump_func
| TODO_verify_flow
/* todo_flags_finish */
3221 /* Walk statements, see what regions are really referenced and remove
3222 those that are unused. */
3225 remove_unreachable_handlers (void)
3227 sbitmap r_reachable
, lp_reachable
;
3233 r_reachable
= sbitmap_alloc (VEC_length (eh_region
, cfun
->eh
->region_array
));
3235 = sbitmap_alloc (VEC_length (eh_landing_pad
, cfun
->eh
->lp_array
));
3236 sbitmap_zero (r_reachable
);
3237 sbitmap_zero (lp_reachable
);
3241 gimple_stmt_iterator gsi
= gsi_start_bb (bb
);
3243 for (gsi
= gsi_start_bb (bb
); !gsi_end_p (gsi
); gsi_next (&gsi
))
3245 gimple stmt
= gsi_stmt (gsi
);
3246 lp_nr
= lookup_stmt_eh_lp (stmt
);
3248 /* Negative LP numbers are MUST_NOT_THROW regions which
3249 are not considered BB enders. */
3251 SET_BIT (r_reachable
, -lp_nr
);
3253 /* Positive LP numbers are real landing pads, are are BB enders. */
3256 gcc_assert (gsi_one_before_end_p (gsi
));
3257 region
= get_eh_region_from_lp_number (lp_nr
);
3258 SET_BIT (r_reachable
, region
->index
);
3259 SET_BIT (lp_reachable
, lp_nr
);
3266 fprintf (dump_file
, "Before removal of unreachable regions:\n");
3267 dump_eh_tree (dump_file
, cfun
);
3268 fprintf (dump_file
, "Reachable regions: ");
3269 dump_sbitmap_file (dump_file
, r_reachable
);
3270 fprintf (dump_file
, "Reachable landing pads: ");
3271 dump_sbitmap_file (dump_file
, lp_reachable
);
3275 VEC_iterate (eh_region
, cfun
->eh
->region_array
, r_nr
, region
); ++r_nr
)
3276 if (region
&& !TEST_BIT (r_reachable
, r_nr
))
3279 fprintf (dump_file
, "Removing unreachable region %d\n", r_nr
);
3280 remove_eh_handler (region
);
3284 VEC_iterate (eh_landing_pad
, cfun
->eh
->lp_array
, lp_nr
, lp
); ++lp_nr
)
3285 if (lp
&& !TEST_BIT (lp_reachable
, lp_nr
))
3288 fprintf (dump_file
, "Removing unreachable landing pad %d\n", lp_nr
);
3289 remove_eh_landing_pad (lp
);
3294 fprintf (dump_file
, "\n\nAfter removal of unreachable regions:\n");
3295 dump_eh_tree (dump_file
, cfun
);
3296 fprintf (dump_file
, "\n\n");
3299 sbitmap_free (r_reachable
);
3300 sbitmap_free (lp_reachable
);
3302 #ifdef ENABLE_CHECKING
3303 verify_eh_tree (cfun
);
3307 /* Remove regions that do not have landing pads. This assumes
3308 that remove_unreachable_handlers has already been run, and
3309 that we've just manipulated the landing pads since then. */
3312 remove_unreachable_handlers_no_lp (void)
3317 for (i
= 1; VEC_iterate (eh_region
, cfun
->eh
->region_array
, i
, r
); ++i
)
3318 if (r
&& r
->landing_pads
== NULL
&& r
->type
!= ERT_MUST_NOT_THROW
)
3321 fprintf (dump_file
, "Removing unreachable region %d\n", i
);
3322 remove_eh_handler (r
);
3326 /* Undo critical edge splitting on an EH landing pad. Earlier, we
3327 optimisticaly split all sorts of edges, including EH edges. The
3328 optimization passes in between may not have needed them; if not,
3329 we should undo the split.
3331 Recognize this case by having one EH edge incoming to the BB and
3332 one normal edge outgoing; BB should be empty apart from the
3333 post_landing_pad label.
3335 Note that this is slightly different from the empty handler case
3336 handled by cleanup_empty_eh, in that the actual handler may yet
3337 have actual code but the landing pad has been separated from the
3338 handler. As such, cleanup_empty_eh relies on this transformation
3339 having been done first. */
3342 unsplit_eh (eh_landing_pad lp
)
3344 basic_block bb
= label_to_block (lp
->post_landing_pad
);
3345 gimple_stmt_iterator gsi
;
3348 /* Quickly check the edge counts on BB for singularity. */
3349 if (EDGE_COUNT (bb
->preds
) != 1 || EDGE_COUNT (bb
->succs
) != 1)
3351 e_in
= EDGE_PRED (bb
, 0);
3352 e_out
= EDGE_SUCC (bb
, 0);
3354 /* Input edge must be EH and output edge must be normal. */
3355 if ((e_in
->flags
& EDGE_EH
) == 0 || (e_out
->flags
& EDGE_EH
) != 0)
3358 /* The block must be empty except for the labels. */
3359 if (!gsi_end_p (gsi_after_labels (bb
)))
3362 /* The destination block must not already have a landing pad
3363 for a different region. */
3364 for (gsi
= gsi_start_bb (e_out
->dest
); !gsi_end_p (gsi
); gsi_next (&gsi
))
3366 gimple stmt
= gsi_stmt (gsi
);
3370 if (gimple_code (stmt
) != GIMPLE_LABEL
)
3372 lab
= gimple_label_label (stmt
);
3373 lp_nr
= EH_LANDING_PAD_NR (lab
);
3374 if (lp_nr
&& get_eh_region_from_lp_number (lp_nr
) != lp
->region
)
3378 /* The new destination block must not already be a destination of
3379 the source block, lest we merge fallthru and eh edges and get
3380 all sorts of confused. */
3381 if (find_edge (e_in
->src
, e_out
->dest
))
3384 /* ??? I can't imagine there would be PHI nodes, since by nature
3385 of critical edge splitting this block should never have been
3386 a dominance frontier. If cfg cleanups somehow confuse this,
3387 due to single edges in and out we ought to have degenerate PHIs
3388 and can easily propagate the PHI arguments. */
3389 gcc_assert (gimple_seq_empty_p (phi_nodes (bb
)));
3391 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
3392 fprintf (dump_file
, "Unsplit EH landing pad %d to block %i.\n",
3393 lp
->index
, e_out
->dest
->index
);
3395 /* Redirect the edge. Since redirect_eh_edge_1 expects to be moving
3396 a successor edge, humor it. But do the real CFG change with the
3397 predecessor of E_OUT in order to preserve the ordering of arguments
3398 to the PHI nodes in E_OUT->DEST. */
3399 redirect_eh_edge_1 (e_in
, e_out
->dest
, false);
3400 redirect_edge_pred (e_out
, e_in
->src
);
3401 e_out
->flags
= e_in
->flags
;
3402 e_out
->probability
= e_in
->probability
;
3403 e_out
->count
= e_in
->count
;
3409 /* Examine each landing pad block and see if it matches unsplit_eh. */
3412 unsplit_all_eh (void)
3414 bool changed
= false;
3418 for (i
= 1; VEC_iterate (eh_landing_pad
, cfun
->eh
->lp_array
, i
, lp
); ++i
)
3420 changed
|= unsplit_eh (lp
);
3425 /* A subroutine of cleanup_empty_eh. Redirect all EH edges incoming
3426 to OLD_BB to NEW_BB; return true on success, false on failure.
3428 OLD_BB_OUT is the edge into NEW_BB from OLD_BB, so if we miss any
3429 PHI variables from OLD_BB we can pick them up from OLD_BB_OUT.
3430 Virtual PHIs may be deleted and marked for renaming. */
3433 cleanup_empty_eh_merge_phis (basic_block new_bb
, basic_block old_bb
,
3436 gimple_stmt_iterator ngsi
, ogsi
;
3439 bitmap rename_virts
;
3440 bitmap ophi_handled
;
3442 FOR_EACH_EDGE (e
, ei
, old_bb
->preds
)
3443 redirect_edge_var_map_clear (e
);
3445 ophi_handled
= BITMAP_ALLOC (NULL
);
3446 rename_virts
= BITMAP_ALLOC (NULL
);
3448 /* First, iterate through the PHIs on NEW_BB and set up the edge_var_map
3449 for the edges we're going to move. */
3450 for (ngsi
= gsi_start_phis (new_bb
); !gsi_end_p (ngsi
); gsi_next (&ngsi
))
3452 gimple ophi
, nphi
= gsi_stmt (ngsi
);
3455 nresult
= gimple_phi_result (nphi
);
3456 nop
= gimple_phi_arg_def (nphi
, old_bb_out
->dest_idx
);
3458 /* Find the corresponding PHI in OLD_BB so we can forward-propagate
3459 the source ssa_name. */
3461 for (ogsi
= gsi_start_phis (old_bb
); !gsi_end_p (ogsi
); gsi_next (&ogsi
))
3463 ophi
= gsi_stmt (ogsi
);
3464 if (gimple_phi_result (ophi
) == nop
)
3469 /* If we did find the corresponding PHI, copy those inputs. */
3472 bitmap_set_bit (ophi_handled
, SSA_NAME_VERSION (nop
));
3473 FOR_EACH_EDGE (e
, ei
, old_bb
->preds
)
3478 if ((e
->flags
& EDGE_EH
) == 0)
3480 oop
= gimple_phi_arg_def (ophi
, e
->dest_idx
);
3481 oloc
= gimple_phi_arg_location (ophi
, e
->dest_idx
);
3482 redirect_edge_var_map_add (e
, nresult
, oop
, oloc
);
3485 /* If we didn't find the PHI, but it's a VOP, remember to rename
3486 it later, assuming all other tests succeed. */
3487 else if (!is_gimple_reg (nresult
))
3488 bitmap_set_bit (rename_virts
, SSA_NAME_VERSION (nresult
));
3489 /* If we didn't find the PHI, and it's a real variable, we know
3490 from the fact that OLD_BB is tree_empty_eh_handler_p that the
3491 variable is unchanged from input to the block and we can simply
3492 re-use the input to NEW_BB from the OLD_BB_OUT edge. */
3496 = gimple_phi_arg_location (nphi
, old_bb_out
->dest_idx
);
3497 FOR_EACH_EDGE (e
, ei
, old_bb
->preds
)
3498 redirect_edge_var_map_add (e
, nresult
, nop
, nloc
);
3502 /* Second, verify that all PHIs from OLD_BB have been handled. If not,
3503 we don't know what values from the other edges into NEW_BB to use. */
3504 for (ogsi
= gsi_start_phis (old_bb
); !gsi_end_p (ogsi
); gsi_next (&ogsi
))
3506 gimple ophi
= gsi_stmt (ogsi
);
3507 tree oresult
= gimple_phi_result (ophi
);
3508 if (!bitmap_bit_p (ophi_handled
, SSA_NAME_VERSION (oresult
)))
3512 /* At this point we know that the merge will succeed. Remove the PHI
3513 nodes for the virtuals that we want to rename. */
3514 if (!bitmap_empty_p (rename_virts
))
3516 for (ngsi
= gsi_start_phis (new_bb
); !gsi_end_p (ngsi
); )
3518 gimple nphi
= gsi_stmt (ngsi
);
3519 tree nresult
= gimple_phi_result (nphi
);
3520 if (bitmap_bit_p (rename_virts
, SSA_NAME_VERSION (nresult
)))
3522 mark_virtual_phi_result_for_renaming (nphi
);
3523 remove_phi_node (&ngsi
, true);
3530 /* Finally, move the edges and update the PHIs. */
3531 for (ei
= ei_start (old_bb
->preds
); (e
= ei_safe_edge (ei
)); )
3532 if (e
->flags
& EDGE_EH
)
3534 redirect_eh_edge_1 (e
, new_bb
, true);
3535 redirect_edge_succ (e
, new_bb
);
3536 flush_pending_stmts (e
);
3541 BITMAP_FREE (ophi_handled
);
3542 BITMAP_FREE (rename_virts
);
3546 FOR_EACH_EDGE (e
, ei
, old_bb
->preds
)
3547 redirect_edge_var_map_clear (e
);
3548 BITMAP_FREE (ophi_handled
);
3549 BITMAP_FREE (rename_virts
);
3553 /* A subroutine of cleanup_empty_eh. Move a landing pad LP from its
3554 old region to NEW_REGION at BB. */
3557 cleanup_empty_eh_move_lp (basic_block bb
, edge e_out
,
3558 eh_landing_pad lp
, eh_region new_region
)
3560 gimple_stmt_iterator gsi
;
3563 for (pp
= &lp
->region
->landing_pads
; *pp
!= lp
; pp
= &(*pp
)->next_lp
)
3567 lp
->region
= new_region
;
3568 lp
->next_lp
= new_region
->landing_pads
;
3569 new_region
->landing_pads
= lp
;
3571 /* Delete the RESX that was matched within the empty handler block. */
3572 gsi
= gsi_last_bb (bb
);
3573 mark_virtual_ops_for_renaming (gsi_stmt (gsi
));
3574 gsi_remove (&gsi
, true);
3576 /* Clean up E_OUT for the fallthru. */
3577 e_out
->flags
= (e_out
->flags
& ~EDGE_EH
) | EDGE_FALLTHRU
;
3578 e_out
->probability
= REG_BR_PROB_BASE
;
3581 /* A subroutine of cleanup_empty_eh. Handle more complex cases of
3582 unsplitting than unsplit_eh was prepared to handle, e.g. when
3583 multiple incoming edges and phis are involved. */
3586 cleanup_empty_eh_unsplit (basic_block bb
, edge e_out
, eh_landing_pad olp
)
3588 gimple_stmt_iterator gsi
;
3592 /* We really ought not have totally lost everything following
3593 a landing pad label. Given that BB is empty, there had better
3595 gcc_assert (e_out
!= NULL
);
3597 /* Look for an EH label in the successor block. */
3599 for (gsi
= gsi_start_bb (e_out
->dest
); !gsi_end_p (gsi
); gsi_next (&gsi
))
3601 gimple stmt
= gsi_stmt (gsi
);
3602 if (gimple_code (stmt
) != GIMPLE_LABEL
)
3604 lab
= gimple_label_label (stmt
);
3605 if (EH_LANDING_PAD_NR (lab
))
3611 /* The other label had better be part of the same EH region. Given that
3612 we've not lowered RESX, there should be no way to have a totally empty
3613 landing pad that crosses to another EH region. */
3614 nlp
= get_eh_landing_pad_from_number (EH_LANDING_PAD_NR (lab
));
3615 gcc_assert (nlp
->region
== olp
->region
);
3617 /* Attempt to move the PHIs into the successor block. */
3618 if (cleanup_empty_eh_merge_phis (e_out
->dest
, bb
, e_out
))
3620 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
3622 "Unsplit EH landing pad %d to block %d via lp %d.\n",
3623 olp
->index
, e_out
->dest
->index
, nlp
->index
);
3625 remove_eh_landing_pad (olp
);
3632 /* Examine the block associated with LP to determine if it's an empty
3633 handler for its EH region. If so, attempt to redirect EH edges to
3634 an outer region. Return true the CFG was updated in any way. This
3635 is similar to jump forwarding, just across EH edges. */
3638 cleanup_empty_eh (eh_landing_pad lp
)
3640 basic_block bb
= label_to_block (lp
->post_landing_pad
);
3641 gimple_stmt_iterator gsi
;
3643 eh_region new_region
;
3646 bool has_non_eh_pred
;
3649 /* There can be zero or one edges out of BB. This is the quickest test. */
3650 switch (EDGE_COUNT (bb
->succs
))
3656 e_out
= EDGE_SUCC (bb
, 0);
3661 gsi
= gsi_after_labels (bb
);
3663 /* Make sure to skip debug statements. */
3664 if (!gsi_end_p (gsi
) && is_gimple_debug (gsi_stmt (gsi
)))
3665 gsi_next_nondebug (&gsi
);
3667 /* If the block is totally empty, look for more unsplitting cases. */
3668 if (gsi_end_p (gsi
))
3669 return cleanup_empty_eh_unsplit (bb
, e_out
, lp
);
3671 /* The block should consist only of a single RESX statement. */
3672 resx
= gsi_stmt (gsi
);
3673 if (!is_gimple_resx (resx
))
3675 gcc_assert (gsi_one_before_end_p (gsi
));
3677 /* Determine if there are non-EH edges, or resx edges into the handler. */
3678 has_non_eh_pred
= false;
3679 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
3680 if (!(e
->flags
& EDGE_EH
))
3681 has_non_eh_pred
= true;
3683 /* Find the handler that's outer of the empty handler by looking at
3684 where the RESX instruction was vectored. */
3685 new_lp_nr
= lookup_stmt_eh_lp (resx
);
3686 new_region
= get_eh_region_from_lp_number (new_lp_nr
);
3688 /* If there's no destination region within the current function,
3689 redirection is trivial via removing the throwing statements from
3690 the EH region, removing the EH edges, and allowing the block
3691 to go unreachable. */
3692 if (new_region
== NULL
)
3694 gcc_assert (e_out
== NULL
);
3695 for (ei
= ei_start (bb
->preds
); (e
= ei_safe_edge (ei
)); )
3696 if (e
->flags
& EDGE_EH
)
3698 gimple stmt
= last_stmt (e
->src
);
3699 remove_stmt_from_eh_lp (stmt
);
3707 /* If the destination region is a MUST_NOT_THROW, allow the runtime
3708 to handle the abort and allow the blocks to go unreachable. */
3709 if (new_region
->type
== ERT_MUST_NOT_THROW
)
3711 for (ei
= ei_start (bb
->preds
); (e
= ei_safe_edge (ei
)); )
3712 if (e
->flags
& EDGE_EH
)
3714 gimple stmt
= last_stmt (e
->src
);
3715 remove_stmt_from_eh_lp (stmt
);
3716 add_stmt_to_eh_lp (stmt
, new_lp_nr
);
3724 /* Try to redirect the EH edges and merge the PHIs into the destination
3725 landing pad block. If the merge succeeds, we'll already have redirected
3726 all the EH edges. The handler itself will go unreachable if there were
3728 if (cleanup_empty_eh_merge_phis (e_out
->dest
, bb
, e_out
))
3731 /* Finally, if all input edges are EH edges, then we can (potentially)
3732 reduce the number of transfers from the runtime by moving the landing
3733 pad from the original region to the new region. This is a win when
3734 we remove the last CLEANUP region along a particular exception
3735 propagation path. Since nothing changes except for the region with
3736 which the landing pad is associated, the PHI nodes do not need to be
3738 if (!has_non_eh_pred
)
3740 cleanup_empty_eh_move_lp (bb
, e_out
, lp
, new_region
);
3741 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
3742 fprintf (dump_file
, "Empty EH handler %i moved to EH region %i.\n",
3743 lp
->index
, new_region
->index
);
3745 /* ??? The CFG didn't change, but we may have rendered the
3746 old EH region unreachable. Trigger a cleanup there. */
3753 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
3754 fprintf (dump_file
, "Empty EH handler %i removed.\n", lp
->index
);
3755 remove_eh_landing_pad (lp
);
3759 /* Do a post-order traversal of the EH region tree. Examine each
3760 post_landing_pad block and see if we can eliminate it as empty. */
3763 cleanup_all_empty_eh (void)
3765 bool changed
= false;
3769 for (i
= 1; VEC_iterate (eh_landing_pad
, cfun
->eh
->lp_array
, i
, lp
); ++i
)
3771 changed
|= cleanup_empty_eh (lp
);
3776 /* Perform cleanups and lowering of exception handling
3777 1) cleanups regions with handlers doing nothing are optimized out
3778 2) MUST_NOT_THROW regions that became dead because of 1) are optimized out
3779 3) Info about regions that are containing instructions, and regions
3780 reachable via local EH edges is collected
3781 4) Eh tree is pruned for regions no longer neccesary.
3783 TODO: Push MUST_NOT_THROW regions to the root of the EH tree.
3784 Unify those that have the same failure decl and locus.
3788 execute_cleanup_eh (void)
3790 /* Do this first: unsplit_all_eh and cleanup_all_empty_eh can die
3791 looking up unreachable landing pads. */
3792 remove_unreachable_handlers ();
3794 /* Watch out for the region tree vanishing due to all unreachable. */
3795 if (cfun
->eh
->region_tree
&& optimize
)
3797 bool changed
= false;
3799 changed
|= unsplit_all_eh ();
3800 changed
|= cleanup_all_empty_eh ();
3804 free_dominance_info (CDI_DOMINATORS
);
3805 free_dominance_info (CDI_POST_DOMINATORS
);
3807 /* We delayed all basic block deletion, as we may have performed
3808 cleanups on EH edges while non-EH edges were still present. */
3809 delete_unreachable_blocks ();
3811 /* We manipulated the landing pads. Remove any region that no
3812 longer has a landing pad. */
3813 remove_unreachable_handlers_no_lp ();
3815 return TODO_cleanup_cfg
| TODO_update_ssa_only_virtuals
;
3823 gate_cleanup_eh (void)
3825 return cfun
->eh
!= NULL
&& cfun
->eh
->region_tree
!= NULL
;
3828 struct gimple_opt_pass pass_cleanup_eh
= {
3831 "ehcleanup", /* name */
3832 gate_cleanup_eh
, /* gate */
3833 execute_cleanup_eh
, /* execute */
3836 0, /* static_pass_number */
3837 TV_TREE_EH
, /* tv_id */
3838 PROP_gimple_lcf
, /* properties_required */
3839 0, /* properties_provided */
3840 0, /* properties_destroyed */
3841 0, /* todo_flags_start */
3842 TODO_dump_func
/* todo_flags_finish */
3846 /* Verify that BB containing STMT as the last statement, has precisely the
3847 edge that make_eh_edges would create. */
3850 verify_eh_edges (gimple stmt
)
3852 basic_block bb
= gimple_bb (stmt
);
3853 eh_landing_pad lp
= NULL
;
3858 lp_nr
= lookup_stmt_eh_lp (stmt
);
3860 lp
= get_eh_landing_pad_from_number (lp_nr
);
3863 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
3865 if (e
->flags
& EDGE_EH
)
3869 error ("BB %i has multiple EH edges", bb
->index
);
3881 error ("BB %i can not throw but has an EH edge", bb
->index
);
3887 if (!stmt_could_throw_p (stmt
))
3889 error ("BB %i last statement has incorrectly set lp", bb
->index
);
3893 if (eh_edge
== NULL
)
3895 error ("BB %i is missing an EH edge", bb
->index
);
3899 if (eh_edge
->dest
!= label_to_block (lp
->post_landing_pad
))
3901 error ("Incorrect EH edge %i->%i", bb
->index
, eh_edge
->dest
->index
);
3908 /* Similarly, but handle GIMPLE_EH_DISPATCH specifically. */
3911 verify_eh_dispatch_edge (gimple stmt
)
3915 basic_block src
, dst
;
3916 bool want_fallthru
= true;
3920 r
= get_eh_region_from_number (gimple_eh_dispatch_region (stmt
));
3921 src
= gimple_bb (stmt
);
3923 FOR_EACH_EDGE (e
, ei
, src
->succs
)
3924 gcc_assert (e
->aux
== NULL
);
3929 for (c
= r
->u
.eh_try
.first_catch
; c
; c
= c
->next_catch
)
3931 dst
= label_to_block (c
->label
);
3932 e
= find_edge (src
, dst
);
3935 error ("BB %i is missing an edge", src
->index
);
3940 /* A catch-all handler doesn't have a fallthru. */
3941 if (c
->type_list
== NULL
)
3943 want_fallthru
= false;
3949 case ERT_ALLOWED_EXCEPTIONS
:
3950 dst
= label_to_block (r
->u
.allowed
.label
);
3951 e
= find_edge (src
, dst
);
3954 error ("BB %i is missing an edge", src
->index
);
3965 FOR_EACH_EDGE (e
, ei
, src
->succs
)
3967 if (e
->flags
& EDGE_FALLTHRU
)
3969 if (fall_edge
!= NULL
)
3971 error ("BB %i too many fallthru edges", src
->index
);
3980 error ("BB %i has incorrect edge", src
->index
);
3984 if ((fall_edge
!= NULL
) ^ want_fallthru
)
3986 error ("BB %i has incorrect fallthru edge", src
->index
);