1 /* Control flow functions for trees.
2 Copyright (C) 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
3 Contributed by Diego Novillo <dnovillo@redhat.com>
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 2, 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 COPYING. If not, write to
19 the Free Software Foundation, 59 Temple Place - Suite 330,
20 Boston, MA 02111-1307, USA. */
24 #include "coretypes.h"
29 #include "hard-reg-set.h"
30 #include "basic-block.h"
37 #include "langhooks.h"
38 #include "diagnostic.h"
39 #include "tree-flow.h"
41 #include "tree-dump.h"
42 #include "tree-pass.h"
46 #include "cfglayout.h"
48 #include "tree-ssa-propagate.h"
50 /* This file contains functions for building the Control Flow Graph (CFG)
51 for a function tree. */
53 /* Local declarations. */
55 /* Initial capacity for the basic block array. */
56 static const int initial_cfg_capacity
= 20;
58 /* This hash table allows us to efficiently lookup all CASE_LABEL_EXPRs
59 which use a particular edge. The CASE_LABEL_EXPRs are chained together
60 via their TREE_CHAIN field, which we clear after we're done with the
61 hash table to prevent problems with duplication of SWITCH_EXPRs.
63 Access to this list of CASE_LABEL_EXPRs allows us to efficiently
64 update the case vector in response to edge redirections.
66 Right now this table is set up and torn down at key points in the
67 compilation process. It would be nice if we could make the table
68 more persistent. The key is getting notification of changes to
69 the CFG (particularly edge removal, creation and redirection). */
71 struct edge_to_cases_elt
73 /* The edge itself. Necessary for hashing and equality tests. */
76 /* The case labels associated with this edge. We link these up via
77 their TREE_CHAIN field, then we wipe out the TREE_CHAIN fields
78 when we destroy the hash table. This prevents problems when copying
83 static htab_t edge_to_cases
;
88 long num_merged_labels
;
91 static struct cfg_stats_d cfg_stats
;
93 /* Nonzero if we found a computed goto while building basic blocks. */
94 static bool found_computed_goto
;
96 /* Basic blocks and flowgraphs. */
97 static basic_block
create_bb (void *, void *, basic_block
);
98 static void make_blocks (tree
);
99 static void factor_computed_gotos (void);
102 static void make_edges (void);
103 static void make_ctrl_stmt_edges (basic_block
);
104 static void make_exit_edges (basic_block
);
105 static void make_cond_expr_edges (basic_block
);
106 static void make_switch_expr_edges (basic_block
);
107 static void make_goto_expr_edges (basic_block
);
108 static edge
tree_redirect_edge_and_branch (edge
, basic_block
);
109 static edge
tree_try_redirect_by_replacing_jump (edge
, basic_block
);
110 static void split_critical_edges (void);
112 /* Various helpers. */
113 static inline bool stmt_starts_bb_p (tree
, tree
);
114 static int tree_verify_flow_info (void);
115 static void tree_make_forwarder_block (edge
);
116 static void tree_cfg2vcg (FILE *);
118 /* Flowgraph optimization and cleanup. */
119 static void tree_merge_blocks (basic_block
, basic_block
);
120 static bool tree_can_merge_blocks_p (basic_block
, basic_block
);
121 static void remove_bb (basic_block
);
122 static edge
find_taken_edge_computed_goto (basic_block
, tree
);
123 static edge
find_taken_edge_cond_expr (basic_block
, tree
);
124 static edge
find_taken_edge_switch_expr (basic_block
, tree
);
125 static tree
find_case_label_for_value (tree
, tree
);
128 init_empty_tree_cfg (void)
130 /* Initialize the basic block array. */
132 profile_status
= PROFILE_ABSENT
;
134 last_basic_block
= 0;
135 VARRAY_BB_INIT (basic_block_info
, initial_cfg_capacity
, "basic_block_info");
137 /* Build a mapping of labels to their associated blocks. */
138 VARRAY_BB_INIT (label_to_block_map
, initial_cfg_capacity
,
139 "label to block map");
141 ENTRY_BLOCK_PTR
->next_bb
= EXIT_BLOCK_PTR
;
142 EXIT_BLOCK_PTR
->prev_bb
= ENTRY_BLOCK_PTR
;
145 /*---------------------------------------------------------------------------
147 ---------------------------------------------------------------------------*/
149 /* Entry point to the CFG builder for trees. TP points to the list of
150 statements to be added to the flowgraph. */
153 build_tree_cfg (tree
*tp
)
155 /* Register specific tree functions. */
156 tree_register_cfg_hooks ();
158 memset ((void *) &cfg_stats
, 0, sizeof (cfg_stats
));
160 init_empty_tree_cfg ();
162 found_computed_goto
= 0;
165 /* Computed gotos are hell to deal with, especially if there are
166 lots of them with a large number of destinations. So we factor
167 them to a common computed goto location before we build the
168 edge list. After we convert back to normal form, we will un-factor
169 the computed gotos since factoring introduces an unwanted jump. */
170 if (found_computed_goto
)
171 factor_computed_gotos ();
173 /* Make sure there is always at least one block, even if it's empty. */
174 if (n_basic_blocks
== 0)
175 create_empty_bb (ENTRY_BLOCK_PTR
);
177 /* Adjust the size of the array. */
178 VARRAY_GROW (basic_block_info
, n_basic_blocks
);
180 /* To speed up statement iterator walks, we first purge dead labels. */
181 cleanup_dead_labels ();
183 /* Group case nodes to reduce the number of edges.
184 We do this after cleaning up dead labels because otherwise we miss
185 a lot of obvious case merging opportunities. */
186 group_case_labels ();
188 /* Create the edges of the flowgraph. */
191 /* Debugging dumps. */
193 /* Write the flowgraph to a VCG file. */
195 int local_dump_flags
;
196 FILE *dump_file
= dump_begin (TDI_vcg
, &local_dump_flags
);
199 tree_cfg2vcg (dump_file
);
200 dump_end (TDI_vcg
, dump_file
);
204 #ifdef ENABLE_CHECKING
208 /* Dump a textual representation of the flowgraph. */
210 dump_tree_cfg (dump_file
, dump_flags
);
214 execute_build_cfg (void)
216 build_tree_cfg (&DECL_SAVED_TREE (current_function_decl
));
219 struct tree_opt_pass pass_build_cfg
=
223 execute_build_cfg
, /* execute */
226 0, /* static_pass_number */
227 TV_TREE_CFG
, /* tv_id */
228 PROP_gimple_leh
, /* properties_required */
229 PROP_cfg
, /* properties_provided */
230 0, /* properties_destroyed */
231 0, /* todo_flags_start */
232 TODO_verify_stmts
, /* todo_flags_finish */
236 /* Search the CFG for any computed gotos. If found, factor them to a
237 common computed goto site. Also record the location of that site so
238 that we can un-factor the gotos after we have converted back to
242 factor_computed_gotos (void)
245 tree factored_label_decl
= NULL
;
247 tree factored_computed_goto_label
= NULL
;
248 tree factored_computed_goto
= NULL
;
250 /* We know there are one or more computed gotos in this function.
251 Examine the last statement in each basic block to see if the block
252 ends with a computed goto. */
256 block_stmt_iterator bsi
= bsi_last (bb
);
261 last
= bsi_stmt (bsi
);
263 /* Ignore the computed goto we create when we factor the original
265 if (last
== factored_computed_goto
)
268 /* If the last statement is a computed goto, factor it. */
269 if (computed_goto_p (last
))
273 /* The first time we find a computed goto we need to create
274 the factored goto block and the variable each original
275 computed goto will use for their goto destination. */
276 if (! factored_computed_goto
)
278 basic_block new_bb
= create_empty_bb (bb
);
279 block_stmt_iterator new_bsi
= bsi_start (new_bb
);
281 /* Create the destination of the factored goto. Each original
282 computed goto will put its desired destination into this
283 variable and jump to the label we create immediately
285 var
= create_tmp_var (ptr_type_node
, "gotovar");
287 /* Build a label for the new block which will contain the
288 factored computed goto. */
289 factored_label_decl
= create_artificial_label ();
290 factored_computed_goto_label
291 = build1 (LABEL_EXPR
, void_type_node
, factored_label_decl
);
292 bsi_insert_after (&new_bsi
, factored_computed_goto_label
,
295 /* Build our new computed goto. */
296 factored_computed_goto
= build1 (GOTO_EXPR
, void_type_node
, var
);
297 bsi_insert_after (&new_bsi
, factored_computed_goto
,
301 /* Copy the original computed goto's destination into VAR. */
302 assignment
= build (MODIFY_EXPR
, ptr_type_node
,
303 var
, GOTO_DESTINATION (last
));
304 bsi_insert_before (&bsi
, assignment
, BSI_SAME_STMT
);
306 /* And re-vector the computed goto to the new destination. */
307 GOTO_DESTINATION (last
) = factored_label_decl
;
313 /* Build a flowgraph for the statement_list STMT_LIST. */
316 make_blocks (tree stmt_list
)
318 tree_stmt_iterator i
= tsi_start (stmt_list
);
320 bool start_new_block
= true;
321 bool first_stmt_of_list
= true;
322 basic_block bb
= ENTRY_BLOCK_PTR
;
324 while (!tsi_end_p (i
))
331 /* If the statement starts a new basic block or if we have determined
332 in a previous pass that we need to create a new block for STMT, do
334 if (start_new_block
|| stmt_starts_bb_p (stmt
, prev_stmt
))
336 if (!first_stmt_of_list
)
337 stmt_list
= tsi_split_statement_list_before (&i
);
338 bb
= create_basic_block (stmt_list
, NULL
, bb
);
339 start_new_block
= false;
342 /* Now add STMT to BB and create the subgraphs for special statement
344 set_bb_for_stmt (stmt
, bb
);
346 if (computed_goto_p (stmt
))
347 found_computed_goto
= true;
349 /* If STMT is a basic block terminator, set START_NEW_BLOCK for the
351 if (stmt_ends_bb_p (stmt
))
352 start_new_block
= true;
355 first_stmt_of_list
= false;
360 /* Create and return a new empty basic block after bb AFTER. */
363 create_bb (void *h
, void *e
, basic_block after
)
369 /* Create and initialize a new basic block. Since alloc_block uses
370 ggc_alloc_cleared to allocate a basic block, we do not have to
371 clear the newly allocated basic block here. */
374 bb
->index
= last_basic_block
;
376 bb
->stmt_list
= h
? h
: alloc_stmt_list ();
378 /* Add the new block to the linked list of blocks. */
379 link_block (bb
, after
);
381 /* Grow the basic block array if needed. */
382 if ((size_t) last_basic_block
== VARRAY_SIZE (basic_block_info
))
384 size_t new_size
= last_basic_block
+ (last_basic_block
+ 3) / 4;
385 VARRAY_GROW (basic_block_info
, new_size
);
388 /* Add the newly created block to the array. */
389 BASIC_BLOCK (last_basic_block
) = bb
;
394 initialize_bb_rbi (bb
);
399 /*---------------------------------------------------------------------------
401 ---------------------------------------------------------------------------*/
403 /* Fold COND_EXPR_COND of each COND_EXPR. */
406 fold_cond_expr_cond (void)
412 tree stmt
= last_stmt (bb
);
415 && TREE_CODE (stmt
) == COND_EXPR
)
417 tree cond
= fold (COND_EXPR_COND (stmt
));
418 if (integer_zerop (cond
))
419 COND_EXPR_COND (stmt
) = boolean_false_node
;
420 else if (integer_onep (cond
))
421 COND_EXPR_COND (stmt
) = boolean_true_node
;
426 /* Join all the blocks in the flowgraph. */
433 /* Create an edge from entry to the first block with executable
435 make_edge (ENTRY_BLOCK_PTR
, BASIC_BLOCK (0), EDGE_FALLTHRU
);
437 /* Traverse the basic block array placing edges. */
440 tree first
= first_stmt (bb
);
441 tree last
= last_stmt (bb
);
445 /* Edges for statements that always alter flow control. */
446 if (is_ctrl_stmt (last
))
447 make_ctrl_stmt_edges (bb
);
449 /* Edges for statements that sometimes alter flow control. */
450 if (is_ctrl_altering_stmt (last
))
451 make_exit_edges (bb
);
454 /* Finally, if no edges were created above, this is a regular
455 basic block that only needs a fallthru edge. */
456 if (EDGE_COUNT (bb
->succs
) == 0)
457 make_edge (bb
, bb
->next_bb
, EDGE_FALLTHRU
);
460 /* We do not care about fake edges, so remove any that the CFG
461 builder inserted for completeness. */
462 remove_fake_exit_edges ();
464 /* Fold COND_EXPR_COND of each COND_EXPR. */
465 fold_cond_expr_cond ();
467 /* Clean up the graph and warn for unreachable code. */
472 /* Create edges for control statement at basic block BB. */
475 make_ctrl_stmt_edges (basic_block bb
)
477 tree last
= last_stmt (bb
);
480 switch (TREE_CODE (last
))
483 make_goto_expr_edges (bb
);
487 make_edge (bb
, EXIT_BLOCK_PTR
, 0);
491 make_cond_expr_edges (bb
);
495 make_switch_expr_edges (bb
);
499 make_eh_edges (last
);
500 /* Yet another NORETURN hack. */
501 if (EDGE_COUNT (bb
->succs
) == 0)
502 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
511 /* Create exit edges for statements in block BB that alter the flow of
512 control. Statements that alter the control flow are 'goto', 'return'
513 and calls to non-returning functions. */
516 make_exit_edges (basic_block bb
)
518 tree last
= last_stmt (bb
), op
;
521 switch (TREE_CODE (last
))
526 /* If this function receives a nonlocal goto, then we need to
527 make edges from this call site to all the nonlocal goto
529 if (TREE_SIDE_EFFECTS (last
)
530 && current_function_has_nonlocal_label
)
531 make_goto_expr_edges (bb
);
533 /* If this statement has reachable exception handlers, then
534 create abnormal edges to them. */
535 make_eh_edges (last
);
537 /* Some calls are known not to return. For such calls we create
540 We really need to revamp how we build edges so that it's not
541 such a bloody pain to avoid creating edges for this case since
542 all we do is remove these edges when we're done building the
544 if (call_expr_flags (last
) & ECF_NORETURN
)
546 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
550 /* Don't forget the fall-thru edge. */
551 make_edge (bb
, bb
->next_bb
, EDGE_FALLTHRU
);
555 /* A MODIFY_EXPR may have a CALL_EXPR on its RHS and the CALL_EXPR
556 may have an abnormal edge. Search the RHS for this case and
557 create any required edges. */
558 op
= get_call_expr_in (last
);
559 if (op
&& TREE_SIDE_EFFECTS (op
)
560 && current_function_has_nonlocal_label
)
561 make_goto_expr_edges (bb
);
563 make_eh_edges (last
);
564 make_edge (bb
, bb
->next_bb
, EDGE_FALLTHRU
);
573 /* Create the edges for a COND_EXPR starting at block BB.
574 At this point, both clauses must contain only simple gotos. */
577 make_cond_expr_edges (basic_block bb
)
579 tree entry
= last_stmt (bb
);
580 basic_block then_bb
, else_bb
;
581 tree then_label
, else_label
;
584 gcc_assert (TREE_CODE (entry
) == COND_EXPR
);
586 /* Entry basic blocks for each component. */
587 then_label
= GOTO_DESTINATION (COND_EXPR_THEN (entry
));
588 else_label
= GOTO_DESTINATION (COND_EXPR_ELSE (entry
));
589 then_bb
= label_to_block (then_label
);
590 else_bb
= label_to_block (else_label
);
592 make_edge (bb
, then_bb
, EDGE_TRUE_VALUE
);
593 make_edge (bb
, else_bb
, EDGE_FALSE_VALUE
);
596 /* Hashing routine for EDGE_TO_CASES. */
599 edge_to_cases_hash (const void *p
)
601 edge e
= ((struct edge_to_cases_elt
*)p
)->e
;
603 /* Hash on the edge itself (which is a pointer). */
604 return htab_hash_pointer (e
);
607 /* Equality routine for EDGE_TO_CASES, edges are unique, so testing
608 for equality is just a pointer comparison. */
611 edge_to_cases_eq (const void *p1
, const void *p2
)
613 edge e1
= ((struct edge_to_cases_elt
*)p1
)->e
;
614 edge e2
= ((struct edge_to_cases_elt
*)p2
)->e
;
619 /* Called for each element in the hash table (P) as we delete the
620 edge to cases hash table.
622 Clear all the TREE_CHAINs to prevent problems with copying of
623 SWITCH_EXPRs and structure sharing rules, then free the hash table
627 edge_to_cases_cleanup (void *p
)
629 struct edge_to_cases_elt
*elt
= p
;
632 for (t
= elt
->case_labels
; t
; t
= next
)
634 next
= TREE_CHAIN (t
);
635 TREE_CHAIN (t
) = NULL
;
640 /* Start recording information mapping edges to case labels. */
643 start_recording_case_labels (void)
645 gcc_assert (edge_to_cases
== NULL
);
647 edge_to_cases
= htab_create (37,
650 edge_to_cases_cleanup
);
653 /* Return nonzero if we are recording information for case labels. */
656 recording_case_labels_p (void)
658 return (edge_to_cases
!= NULL
);
661 /* Stop recording information mapping edges to case labels and
662 remove any information we have recorded. */
664 end_recording_case_labels (void)
666 htab_delete (edge_to_cases
);
667 edge_to_cases
= NULL
;
670 /* Record that CASE_LABEL (a CASE_LABEL_EXPR) references edge E. */
673 record_switch_edge (edge e
, tree case_label
)
675 struct edge_to_cases_elt
*elt
;
678 /* Build a hash table element so we can see if E is already
680 elt
= xmalloc (sizeof (struct edge_to_cases_elt
));
682 elt
->case_labels
= case_label
;
684 slot
= htab_find_slot (edge_to_cases
, elt
, INSERT
);
688 /* E was not in the hash table. Install E into the hash table. */
693 /* E was already in the hash table. Free ELT as we do not need it
697 /* Get the entry stored in the hash table. */
698 elt
= (struct edge_to_cases_elt
*) *slot
;
700 /* Add it to the chain of CASE_LABEL_EXPRs referencing E. */
701 TREE_CHAIN (case_label
) = elt
->case_labels
;
702 elt
->case_labels
= case_label
;
706 /* If we are inside a {start,end}_recording_cases block, then return
707 a chain of CASE_LABEL_EXPRs from T which reference E.
709 Otherwise return NULL. */
712 get_cases_for_edge (edge e
, tree t
)
714 struct edge_to_cases_elt elt
, *elt_p
;
719 /* If we are not recording cases, then we do not have CASE_LABEL_EXPR
720 chains available. Return NULL so the caller can detect this case. */
721 if (!recording_case_labels_p ())
726 elt
.case_labels
= NULL
;
727 slot
= htab_find_slot (edge_to_cases
, &elt
, NO_INSERT
);
731 elt_p
= (struct edge_to_cases_elt
*)*slot
;
732 return elt_p
->case_labels
;
735 /* If we did not find E in the hash table, then this must be the first
736 time we have been queried for information about E & T. Add all the
737 elements from T to the hash table then perform the query again. */
739 vec
= SWITCH_LABELS (t
);
740 n
= TREE_VEC_LENGTH (vec
);
741 for (i
= 0; i
< n
; i
++)
743 tree lab
= CASE_LABEL (TREE_VEC_ELT (vec
, i
));
744 basic_block label_bb
= label_to_block (lab
);
745 record_switch_edge (find_edge (e
->src
, label_bb
), TREE_VEC_ELT (vec
, i
));
750 /* Create the edges for a SWITCH_EXPR starting at block BB.
751 At this point, the switch body has been lowered and the
752 SWITCH_LABELS filled in, so this is in effect a multi-way branch. */
755 make_switch_expr_edges (basic_block bb
)
757 tree entry
= last_stmt (bb
);
761 vec
= SWITCH_LABELS (entry
);
762 n
= TREE_VEC_LENGTH (vec
);
764 for (i
= 0; i
< n
; ++i
)
766 tree lab
= CASE_LABEL (TREE_VEC_ELT (vec
, i
));
767 basic_block label_bb
= label_to_block (lab
);
768 make_edge (bb
, label_bb
, 0);
773 /* Return the basic block holding label DEST. */
776 label_to_block_fn (struct function
*ifun
, tree dest
)
778 int uid
= LABEL_DECL_UID (dest
);
780 /* We would die hard when faced by an undefined label. Emit a label to
781 the very first basic block. This will hopefully make even the dataflow
782 and undefined variable warnings quite right. */
783 if ((errorcount
|| sorrycount
) && uid
< 0)
785 block_stmt_iterator bsi
= bsi_start (BASIC_BLOCK (0));
788 stmt
= build1 (LABEL_EXPR
, void_type_node
, dest
);
789 bsi_insert_before (&bsi
, stmt
, BSI_NEW_STMT
);
790 uid
= LABEL_DECL_UID (dest
);
792 if (VARRAY_SIZE (ifun
->cfg
->x_label_to_block_map
) <= (unsigned int)uid
)
794 return VARRAY_BB (ifun
->cfg
->x_label_to_block_map
, uid
);
797 /* Create edges for a goto statement at block BB. */
800 make_goto_expr_edges (basic_block bb
)
803 basic_block target_bb
;
805 block_stmt_iterator last
= bsi_last (bb
);
807 goto_t
= bsi_stmt (last
);
809 /* If the last statement is not a GOTO (i.e., it is a RETURN_EXPR,
810 CALL_EXPR or MODIFY_EXPR), then the edge is an abnormal edge resulting
811 from a nonlocal goto. */
812 if (TREE_CODE (goto_t
) != GOTO_EXPR
)
816 tree dest
= GOTO_DESTINATION (goto_t
);
819 /* A GOTO to a local label creates normal edges. */
820 if (simple_goto_p (goto_t
))
822 edge e
= make_edge (bb
, label_to_block (dest
), EDGE_FALLTHRU
);
823 #ifdef USE_MAPPED_LOCATION
824 e
->goto_locus
= EXPR_LOCATION (goto_t
);
826 e
->goto_locus
= EXPR_LOCUS (goto_t
);
832 /* Nothing more to do for nonlocal gotos. */
833 if (TREE_CODE (dest
) == LABEL_DECL
)
836 /* Computed gotos remain. */
839 /* Look for the block starting with the destination label. In the
840 case of a computed goto, make an edge to any label block we find
842 FOR_EACH_BB (target_bb
)
844 block_stmt_iterator bsi
;
846 for (bsi
= bsi_start (target_bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
848 tree target
= bsi_stmt (bsi
);
850 if (TREE_CODE (target
) != LABEL_EXPR
)
854 /* Computed GOTOs. Make an edge to every label block that has
855 been marked as a potential target for a computed goto. */
856 (FORCED_LABEL (LABEL_EXPR_LABEL (target
)) && for_call
== 0)
857 /* Nonlocal GOTO target. Make an edge to every label block
858 that has been marked as a potential target for a nonlocal
860 || (DECL_NONLOCAL (LABEL_EXPR_LABEL (target
)) && for_call
== 1))
862 make_edge (bb
, target_bb
, EDGE_ABNORMAL
);
868 /* Degenerate case of computed goto with no labels. */
869 if (!for_call
&& EDGE_COUNT (bb
->succs
) == 0)
870 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
874 /*---------------------------------------------------------------------------
876 ---------------------------------------------------------------------------*/
878 /* Cleanup useless labels in basic blocks. This is something we wish
879 to do early because it allows us to group case labels before creating
880 the edges for the CFG, and it speeds up block statement iterators in
882 We only run this pass once, running it more than once is probably not
885 /* A map from basic block index to the leading label of that block. */
886 static tree
*label_for_bb
;
888 /* Callback for for_each_eh_region. Helper for cleanup_dead_labels. */
890 update_eh_label (struct eh_region
*region
)
892 tree old_label
= get_eh_region_tree_label (region
);
896 basic_block bb
= label_to_block (old_label
);
898 /* ??? After optimizing, there may be EH regions with labels
899 that have already been removed from the function body, so
900 there is no basic block for them. */
904 new_label
= label_for_bb
[bb
->index
];
905 set_eh_region_tree_label (region
, new_label
);
909 /* Given LABEL return the first label in the same basic block. */
911 main_block_label (tree label
)
913 basic_block bb
= label_to_block (label
);
915 /* label_to_block possibly inserted undefined label into the chain. */
916 if (!label_for_bb
[bb
->index
])
917 label_for_bb
[bb
->index
] = label
;
918 return label_for_bb
[bb
->index
];
921 /* Cleanup redundant labels. This is a three-step process:
922 1) Find the leading label for each block.
923 2) Redirect all references to labels to the leading labels.
924 3) Cleanup all useless labels. */
927 cleanup_dead_labels (void)
930 label_for_bb
= xcalloc (last_basic_block
, sizeof (tree
));
932 /* Find a suitable label for each block. We use the first user-defined
933 label if there is one, or otherwise just the first label we see. */
936 block_stmt_iterator i
;
938 for (i
= bsi_start (bb
); !bsi_end_p (i
); bsi_next (&i
))
940 tree label
, stmt
= bsi_stmt (i
);
942 if (TREE_CODE (stmt
) != LABEL_EXPR
)
945 label
= LABEL_EXPR_LABEL (stmt
);
947 /* If we have not yet seen a label for the current block,
948 remember this one and see if there are more labels. */
949 if (! label_for_bb
[bb
->index
])
951 label_for_bb
[bb
->index
] = label
;
955 /* If we did see a label for the current block already, but it
956 is an artificially created label, replace it if the current
957 label is a user defined label. */
958 if (! DECL_ARTIFICIAL (label
)
959 && DECL_ARTIFICIAL (label_for_bb
[bb
->index
]))
961 label_for_bb
[bb
->index
] = label
;
967 /* Now redirect all jumps/branches to the selected label.
968 First do so for each block ending in a control statement. */
971 tree stmt
= last_stmt (bb
);
975 switch (TREE_CODE (stmt
))
979 tree true_branch
, false_branch
;
981 true_branch
= COND_EXPR_THEN (stmt
);
982 false_branch
= COND_EXPR_ELSE (stmt
);
984 GOTO_DESTINATION (true_branch
)
985 = main_block_label (GOTO_DESTINATION (true_branch
));
986 GOTO_DESTINATION (false_branch
)
987 = main_block_label (GOTO_DESTINATION (false_branch
));
995 tree vec
= SWITCH_LABELS (stmt
);
996 size_t n
= TREE_VEC_LENGTH (vec
);
998 /* Replace all destination labels. */
999 for (i
= 0; i
< n
; ++i
)
1001 tree elt
= TREE_VEC_ELT (vec
, i
);
1002 tree label
= main_block_label (CASE_LABEL (elt
));
1003 CASE_LABEL (elt
) = label
;
1008 /* We have to handle GOTO_EXPRs until they're removed, and we don't
1009 remove them until after we've created the CFG edges. */
1011 if (! computed_goto_p (stmt
))
1013 GOTO_DESTINATION (stmt
)
1014 = main_block_label (GOTO_DESTINATION (stmt
));
1023 for_each_eh_region (update_eh_label
);
1025 /* Finally, purge dead labels. All user-defined labels and labels that
1026 can be the target of non-local gotos are preserved. */
1029 block_stmt_iterator i
;
1030 tree label_for_this_bb
= label_for_bb
[bb
->index
];
1032 if (! label_for_this_bb
)
1035 for (i
= bsi_start (bb
); !bsi_end_p (i
); )
1037 tree label
, stmt
= bsi_stmt (i
);
1039 if (TREE_CODE (stmt
) != LABEL_EXPR
)
1042 label
= LABEL_EXPR_LABEL (stmt
);
1044 if (label
== label_for_this_bb
1045 || ! DECL_ARTIFICIAL (label
)
1046 || DECL_NONLOCAL (label
))
1053 free (label_for_bb
);
1056 /* Look for blocks ending in a multiway branch (a SWITCH_EXPR in GIMPLE),
1057 and scan the sorted vector of cases. Combine the ones jumping to the
1059 Eg. three separate entries 1: 2: 3: become one entry 1..3: */
1062 group_case_labels (void)
1068 tree stmt
= last_stmt (bb
);
1069 if (stmt
&& TREE_CODE (stmt
) == SWITCH_EXPR
)
1071 tree labels
= SWITCH_LABELS (stmt
);
1072 int old_size
= TREE_VEC_LENGTH (labels
);
1073 int i
, j
, new_size
= old_size
;
1074 tree default_case
= TREE_VEC_ELT (labels
, old_size
- 1);
1077 /* The default label is always the last case in a switch
1078 statement after gimplification. */
1079 default_label
= CASE_LABEL (default_case
);
1081 /* Look for possible opportunities to merge cases.
1082 Ignore the last element of the label vector because it
1083 must be the default case. */
1085 while (i
< old_size
- 1)
1087 tree base_case
, base_label
, base_high
;
1088 base_case
= TREE_VEC_ELT (labels
, i
);
1090 gcc_assert (base_case
);
1091 base_label
= CASE_LABEL (base_case
);
1093 /* Discard cases that have the same destination as the
1095 if (base_label
== default_label
)
1097 TREE_VEC_ELT (labels
, i
) = NULL_TREE
;
1103 base_high
= CASE_HIGH (base_case
) ?
1104 CASE_HIGH (base_case
) : CASE_LOW (base_case
);
1106 /* Try to merge case labels. Break out when we reach the end
1107 of the label vector or when we cannot merge the next case
1108 label with the current one. */
1109 while (i
< old_size
- 1)
1111 tree merge_case
= TREE_VEC_ELT (labels
, i
);
1112 tree merge_label
= CASE_LABEL (merge_case
);
1113 tree t
= int_const_binop (PLUS_EXPR
, base_high
,
1114 integer_one_node
, 1);
1116 /* Merge the cases if they jump to the same place,
1117 and their ranges are consecutive. */
1118 if (merge_label
== base_label
1119 && tree_int_cst_equal (CASE_LOW (merge_case
), t
))
1121 base_high
= CASE_HIGH (merge_case
) ?
1122 CASE_HIGH (merge_case
) : CASE_LOW (merge_case
);
1123 CASE_HIGH (base_case
) = base_high
;
1124 TREE_VEC_ELT (labels
, i
) = NULL_TREE
;
1133 /* Compress the case labels in the label vector, and adjust the
1134 length of the vector. */
1135 for (i
= 0, j
= 0; i
< new_size
; i
++)
1137 while (! TREE_VEC_ELT (labels
, j
))
1139 TREE_VEC_ELT (labels
, i
) = TREE_VEC_ELT (labels
, j
++);
1141 TREE_VEC_LENGTH (labels
) = new_size
;
1146 /* Checks whether we can merge block B into block A. */
1149 tree_can_merge_blocks_p (basic_block a
, basic_block b
)
1152 block_stmt_iterator bsi
;
1155 if (!single_succ_p (a
))
1158 if (single_succ_edge (a
)->flags
& EDGE_ABNORMAL
)
1161 if (single_succ (a
) != b
)
1164 if (!single_pred_p (b
))
1167 if (b
== EXIT_BLOCK_PTR
)
1170 /* If A ends by a statement causing exceptions or something similar, we
1171 cannot merge the blocks. */
1172 stmt
= last_stmt (a
);
1173 if (stmt
&& stmt_ends_bb_p (stmt
))
1176 /* Do not allow a block with only a non-local label to be merged. */
1177 if (stmt
&& TREE_CODE (stmt
) == LABEL_EXPR
1178 && DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt
)))
1181 /* It must be possible to eliminate all phi nodes in B. If ssa form
1182 is not up-to-date, we cannot eliminate any phis. */
1183 phi
= phi_nodes (b
);
1186 if (need_ssa_update_p ())
1189 for (; phi
; phi
= PHI_CHAIN (phi
))
1190 if (!is_gimple_reg (PHI_RESULT (phi
))
1191 && !may_propagate_copy (PHI_RESULT (phi
), PHI_ARG_DEF (phi
, 0)))
1195 /* Do not remove user labels. */
1196 for (bsi
= bsi_start (b
); !bsi_end_p (bsi
); bsi_next (&bsi
))
1198 stmt
= bsi_stmt (bsi
);
1199 if (TREE_CODE (stmt
) != LABEL_EXPR
)
1201 if (!DECL_ARTIFICIAL (LABEL_EXPR_LABEL (stmt
)))
1205 /* Protect the loop latches. */
1207 && b
->loop_father
->latch
== b
)
1213 /* Replaces all uses of NAME by VAL. */
1216 replace_uses_by (tree name
, tree val
)
1218 imm_use_iterator imm_iter
;
1223 VEC(tree
,heap
) *stmts
= VEC_alloc (tree
, heap
, 20);
1225 FOR_EACH_IMM_USE_SAFE (use
, imm_iter
, name
)
1227 stmt
= USE_STMT (use
);
1231 if (TREE_CODE (stmt
) == PHI_NODE
)
1233 e
= PHI_ARG_EDGE (stmt
, PHI_ARG_INDEX_FROM_USE (use
));
1234 if (e
->flags
& EDGE_ABNORMAL
)
1236 /* This can only occur for virtual operands, since
1237 for the real ones SSA_NAME_OCCURS_IN_ABNORMAL_PHI (name))
1238 would prevent replacement. */
1239 gcc_assert (!is_gimple_reg (name
));
1240 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (val
) = 1;
1244 VEC_safe_push (tree
, heap
, stmts
, stmt
);
1247 /* We do not update the statements in the loop above. Consider
1250 If we performed the update in the first loop, the statement
1251 would be rescanned after first occurrence of w is replaced,
1252 the new uses would be placed to the beginning of the list,
1253 and we would never process them. */
1254 for (i
= 0; VEC_iterate (tree
, stmts
, i
, stmt
); i
++)
1258 fold_stmt_inplace (stmt
);
1260 rhs
= get_rhs (stmt
);
1261 if (TREE_CODE (rhs
) == ADDR_EXPR
)
1262 recompute_tree_invarant_for_addr_expr (rhs
);
1267 VEC_free (tree
, heap
, stmts
);
1270 /* Merge block B into block A. */
1273 tree_merge_blocks (basic_block a
, basic_block b
)
1275 block_stmt_iterator bsi
;
1276 tree_stmt_iterator last
;
1280 fprintf (dump_file
, "Merging blocks %d and %d\n", a
->index
, b
->index
);
1282 /* Remove the phi nodes. */
1284 for (phi
= phi_nodes (b
); phi
; phi
= phi_nodes (b
))
1286 tree def
= PHI_RESULT (phi
), use
= PHI_ARG_DEF (phi
, 0);
1289 if (!may_propagate_copy (def
, use
)
1290 /* Propagating pointers might cause the set of vops for statements
1291 to be changed, and thus require ssa form update. */
1292 || (is_gimple_reg (def
)
1293 && POINTER_TYPE_P (TREE_TYPE (def
))))
1295 gcc_assert (is_gimple_reg (def
));
1297 /* Note that just emitting the copies is fine -- there is no problem
1298 with ordering of phi nodes. This is because A is the single
1299 predecessor of B, therefore results of the phi nodes cannot
1300 appear as arguments of the phi nodes. */
1301 copy
= build2 (MODIFY_EXPR
, void_type_node
, def
, use
);
1302 bsi_insert_after (&bsi
, copy
, BSI_NEW_STMT
);
1303 SET_PHI_RESULT (phi
, NULL_TREE
);
1304 SSA_NAME_DEF_STMT (def
) = copy
;
1307 replace_uses_by (def
, use
);
1308 remove_phi_node (phi
, NULL
);
1311 /* Ensure that B follows A. */
1312 move_block_after (b
, a
);
1314 gcc_assert (single_succ_edge (a
)->flags
& EDGE_FALLTHRU
);
1315 gcc_assert (!last_stmt (a
) || !stmt_ends_bb_p (last_stmt (a
)));
1317 /* Remove labels from B and set bb_for_stmt to A for other statements. */
1318 for (bsi
= bsi_start (b
); !bsi_end_p (bsi
);)
1320 if (TREE_CODE (bsi_stmt (bsi
)) == LABEL_EXPR
)
1322 tree label
= bsi_stmt (bsi
);
1325 /* Now that we can thread computed gotos, we might have
1326 a situation where we have a forced label in block B
1327 However, the label at the start of block B might still be
1328 used in other ways (think about the runtime checking for
1329 Fortran assigned gotos). So we can not just delete the
1330 label. Instead we move the label to the start of block A. */
1331 if (FORCED_LABEL (LABEL_EXPR_LABEL (label
)))
1333 block_stmt_iterator dest_bsi
= bsi_start (a
);
1334 bsi_insert_before (&dest_bsi
, label
, BSI_NEW_STMT
);
1339 set_bb_for_stmt (bsi_stmt (bsi
), a
);
1344 /* Merge the chains. */
1345 last
= tsi_last (a
->stmt_list
);
1346 tsi_link_after (&last
, b
->stmt_list
, TSI_NEW_STMT
);
1347 b
->stmt_list
= NULL
;
1351 /* Walk the function tree removing unnecessary statements.
1353 * Empty statement nodes are removed
1355 * Unnecessary TRY_FINALLY and TRY_CATCH blocks are removed
1357 * Unnecessary COND_EXPRs are removed
1359 * Some unnecessary BIND_EXPRs are removed
1361 Clearly more work could be done. The trick is doing the analysis
1362 and removal fast enough to be a net improvement in compile times.
1364 Note that when we remove a control structure such as a COND_EXPR
1365 BIND_EXPR, or TRY block, we will need to repeat this optimization pass
1366 to ensure we eliminate all the useless code. */
1377 static void remove_useless_stmts_1 (tree
*, struct rus_data
*);
1380 remove_useless_stmts_warn_notreached (tree stmt
)
1382 if (EXPR_HAS_LOCATION (stmt
))
1384 location_t loc
= EXPR_LOCATION (stmt
);
1385 if (LOCATION_LINE (loc
) > 0)
1387 warning (0, "%Hwill never be executed", &loc
);
1392 switch (TREE_CODE (stmt
))
1394 case STATEMENT_LIST
:
1396 tree_stmt_iterator i
;
1397 for (i
= tsi_start (stmt
); !tsi_end_p (i
); tsi_next (&i
))
1398 if (remove_useless_stmts_warn_notreached (tsi_stmt (i
)))
1404 if (remove_useless_stmts_warn_notreached (COND_EXPR_COND (stmt
)))
1406 if (remove_useless_stmts_warn_notreached (COND_EXPR_THEN (stmt
)))
1408 if (remove_useless_stmts_warn_notreached (COND_EXPR_ELSE (stmt
)))
1412 case TRY_FINALLY_EXPR
:
1413 case TRY_CATCH_EXPR
:
1414 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt
, 0)))
1416 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt
, 1)))
1421 return remove_useless_stmts_warn_notreached (CATCH_BODY (stmt
));
1422 case EH_FILTER_EXPR
:
1423 return remove_useless_stmts_warn_notreached (EH_FILTER_FAILURE (stmt
));
1425 return remove_useless_stmts_warn_notreached (BIND_EXPR_BLOCK (stmt
));
1428 /* Not a live container. */
1436 remove_useless_stmts_cond (tree
*stmt_p
, struct rus_data
*data
)
1438 tree then_clause
, else_clause
, cond
;
1439 bool save_has_label
, then_has_label
, else_has_label
;
1441 save_has_label
= data
->has_label
;
1442 data
->has_label
= false;
1443 data
->last_goto
= NULL
;
1445 remove_useless_stmts_1 (&COND_EXPR_THEN (*stmt_p
), data
);
1447 then_has_label
= data
->has_label
;
1448 data
->has_label
= false;
1449 data
->last_goto
= NULL
;
1451 remove_useless_stmts_1 (&COND_EXPR_ELSE (*stmt_p
), data
);
1453 else_has_label
= data
->has_label
;
1454 data
->has_label
= save_has_label
| then_has_label
| else_has_label
;
1456 then_clause
= COND_EXPR_THEN (*stmt_p
);
1457 else_clause
= COND_EXPR_ELSE (*stmt_p
);
1458 cond
= fold (COND_EXPR_COND (*stmt_p
));
1460 /* If neither arm does anything at all, we can remove the whole IF. */
1461 if (!TREE_SIDE_EFFECTS (then_clause
) && !TREE_SIDE_EFFECTS (else_clause
))
1463 *stmt_p
= build_empty_stmt ();
1464 data
->repeat
= true;
1467 /* If there are no reachable statements in an arm, then we can
1468 zap the entire conditional. */
1469 else if (integer_nonzerop (cond
) && !else_has_label
)
1471 if (warn_notreached
)
1472 remove_useless_stmts_warn_notreached (else_clause
);
1473 *stmt_p
= then_clause
;
1474 data
->repeat
= true;
1476 else if (integer_zerop (cond
) && !then_has_label
)
1478 if (warn_notreached
)
1479 remove_useless_stmts_warn_notreached (then_clause
);
1480 *stmt_p
= else_clause
;
1481 data
->repeat
= true;
1484 /* Check a couple of simple things on then/else with single stmts. */
1487 tree then_stmt
= expr_only (then_clause
);
1488 tree else_stmt
= expr_only (else_clause
);
1490 /* Notice branches to a common destination. */
1491 if (then_stmt
&& else_stmt
1492 && TREE_CODE (then_stmt
) == GOTO_EXPR
1493 && TREE_CODE (else_stmt
) == GOTO_EXPR
1494 && (GOTO_DESTINATION (then_stmt
) == GOTO_DESTINATION (else_stmt
)))
1496 *stmt_p
= then_stmt
;
1497 data
->repeat
= true;
1500 /* If the THEN/ELSE clause merely assigns a value to a variable or
1501 parameter which is already known to contain that value, then
1502 remove the useless THEN/ELSE clause. */
1503 else if (TREE_CODE (cond
) == VAR_DECL
|| TREE_CODE (cond
) == PARM_DECL
)
1506 && TREE_CODE (else_stmt
) == MODIFY_EXPR
1507 && TREE_OPERAND (else_stmt
, 0) == cond
1508 && integer_zerop (TREE_OPERAND (else_stmt
, 1)))
1509 COND_EXPR_ELSE (*stmt_p
) = alloc_stmt_list ();
1511 else if ((TREE_CODE (cond
) == EQ_EXPR
|| TREE_CODE (cond
) == NE_EXPR
)
1512 && (TREE_CODE (TREE_OPERAND (cond
, 0)) == VAR_DECL
1513 || TREE_CODE (TREE_OPERAND (cond
, 0)) == PARM_DECL
)
1514 && TREE_CONSTANT (TREE_OPERAND (cond
, 1)))
1516 tree stmt
= (TREE_CODE (cond
) == EQ_EXPR
1517 ? then_stmt
: else_stmt
);
1518 tree
*location
= (TREE_CODE (cond
) == EQ_EXPR
1519 ? &COND_EXPR_THEN (*stmt_p
)
1520 : &COND_EXPR_ELSE (*stmt_p
));
1523 && TREE_CODE (stmt
) == MODIFY_EXPR
1524 && TREE_OPERAND (stmt
, 0) == TREE_OPERAND (cond
, 0)
1525 && TREE_OPERAND (stmt
, 1) == TREE_OPERAND (cond
, 1))
1526 *location
= alloc_stmt_list ();
1530 /* Protect GOTOs in the arm of COND_EXPRs from being removed. They
1531 would be re-introduced during lowering. */
1532 data
->last_goto
= NULL
;
1537 remove_useless_stmts_tf (tree
*stmt_p
, struct rus_data
*data
)
1539 bool save_may_branch
, save_may_throw
;
1540 bool this_may_branch
, this_may_throw
;
1542 /* Collect may_branch and may_throw information for the body only. */
1543 save_may_branch
= data
->may_branch
;
1544 save_may_throw
= data
->may_throw
;
1545 data
->may_branch
= false;
1546 data
->may_throw
= false;
1547 data
->last_goto
= NULL
;
1549 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p
, 0), data
);
1551 this_may_branch
= data
->may_branch
;
1552 this_may_throw
= data
->may_throw
;
1553 data
->may_branch
|= save_may_branch
;
1554 data
->may_throw
|= save_may_throw
;
1555 data
->last_goto
= NULL
;
1557 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p
, 1), data
);
1559 /* If the body is empty, then we can emit the FINALLY block without
1560 the enclosing TRY_FINALLY_EXPR. */
1561 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p
, 0)))
1563 *stmt_p
= TREE_OPERAND (*stmt_p
, 1);
1564 data
->repeat
= true;
1567 /* If the handler is empty, then we can emit the TRY block without
1568 the enclosing TRY_FINALLY_EXPR. */
1569 else if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p
, 1)))
1571 *stmt_p
= TREE_OPERAND (*stmt_p
, 0);
1572 data
->repeat
= true;
1575 /* If the body neither throws, nor branches, then we can safely
1576 string the TRY and FINALLY blocks together. */
1577 else if (!this_may_branch
&& !this_may_throw
)
1579 tree stmt
= *stmt_p
;
1580 *stmt_p
= TREE_OPERAND (stmt
, 0);
1581 append_to_statement_list (TREE_OPERAND (stmt
, 1), stmt_p
);
1582 data
->repeat
= true;
1588 remove_useless_stmts_tc (tree
*stmt_p
, struct rus_data
*data
)
1590 bool save_may_throw
, this_may_throw
;
1591 tree_stmt_iterator i
;
1594 /* Collect may_throw information for the body only. */
1595 save_may_throw
= data
->may_throw
;
1596 data
->may_throw
= false;
1597 data
->last_goto
= NULL
;
1599 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p
, 0), data
);
1601 this_may_throw
= data
->may_throw
;
1602 data
->may_throw
= save_may_throw
;
1604 /* If the body cannot throw, then we can drop the entire TRY_CATCH_EXPR. */
1605 if (!this_may_throw
)
1607 if (warn_notreached
)
1608 remove_useless_stmts_warn_notreached (TREE_OPERAND (*stmt_p
, 1));
1609 *stmt_p
= TREE_OPERAND (*stmt_p
, 0);
1610 data
->repeat
= true;
1614 /* Process the catch clause specially. We may be able to tell that
1615 no exceptions propagate past this point. */
1617 this_may_throw
= true;
1618 i
= tsi_start (TREE_OPERAND (*stmt_p
, 1));
1619 stmt
= tsi_stmt (i
);
1620 data
->last_goto
= NULL
;
1622 switch (TREE_CODE (stmt
))
1625 for (; !tsi_end_p (i
); tsi_next (&i
))
1627 stmt
= tsi_stmt (i
);
1628 /* If we catch all exceptions, then the body does not
1629 propagate exceptions past this point. */
1630 if (CATCH_TYPES (stmt
) == NULL
)
1631 this_may_throw
= false;
1632 data
->last_goto
= NULL
;
1633 remove_useless_stmts_1 (&CATCH_BODY (stmt
), data
);
1637 case EH_FILTER_EXPR
:
1638 if (EH_FILTER_MUST_NOT_THROW (stmt
))
1639 this_may_throw
= false;
1640 else if (EH_FILTER_TYPES (stmt
) == NULL
)
1641 this_may_throw
= false;
1642 remove_useless_stmts_1 (&EH_FILTER_FAILURE (stmt
), data
);
1646 /* Otherwise this is a cleanup. */
1647 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p
, 1), data
);
1649 /* If the cleanup is empty, then we can emit the TRY block without
1650 the enclosing TRY_CATCH_EXPR. */
1651 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p
, 1)))
1653 *stmt_p
= TREE_OPERAND (*stmt_p
, 0);
1654 data
->repeat
= true;
1658 data
->may_throw
|= this_may_throw
;
1663 remove_useless_stmts_bind (tree
*stmt_p
, struct rus_data
*data
)
1667 /* First remove anything underneath the BIND_EXPR. */
1668 remove_useless_stmts_1 (&BIND_EXPR_BODY (*stmt_p
), data
);
1670 /* If the BIND_EXPR has no variables, then we can pull everything
1671 up one level and remove the BIND_EXPR, unless this is the toplevel
1672 BIND_EXPR for the current function or an inlined function.
1674 When this situation occurs we will want to apply this
1675 optimization again. */
1676 block
= BIND_EXPR_BLOCK (*stmt_p
);
1677 if (BIND_EXPR_VARS (*stmt_p
) == NULL_TREE
1678 && *stmt_p
!= DECL_SAVED_TREE (current_function_decl
)
1680 || ! BLOCK_ABSTRACT_ORIGIN (block
)
1681 || (TREE_CODE (BLOCK_ABSTRACT_ORIGIN (block
))
1684 *stmt_p
= BIND_EXPR_BODY (*stmt_p
);
1685 data
->repeat
= true;
1691 remove_useless_stmts_goto (tree
*stmt_p
, struct rus_data
*data
)
1693 tree dest
= GOTO_DESTINATION (*stmt_p
);
1695 data
->may_branch
= true;
1696 data
->last_goto
= NULL
;
1698 /* Record the last goto expr, so that we can delete it if unnecessary. */
1699 if (TREE_CODE (dest
) == LABEL_DECL
)
1700 data
->last_goto
= stmt_p
;
1705 remove_useless_stmts_label (tree
*stmt_p
, struct rus_data
*data
)
1707 tree label
= LABEL_EXPR_LABEL (*stmt_p
);
1709 data
->has_label
= true;
1711 /* We do want to jump across non-local label receiver code. */
1712 if (DECL_NONLOCAL (label
))
1713 data
->last_goto
= NULL
;
1715 else if (data
->last_goto
&& GOTO_DESTINATION (*data
->last_goto
) == label
)
1717 *data
->last_goto
= build_empty_stmt ();
1718 data
->repeat
= true;
1721 /* ??? Add something here to delete unused labels. */
1725 /* If the function is "const" or "pure", then clear TREE_SIDE_EFFECTS on its
1726 decl. This allows us to eliminate redundant or useless
1727 calls to "const" functions.
1729 Gimplifier already does the same operation, but we may notice functions
1730 being const and pure once their calls has been gimplified, so we need
1731 to update the flag. */
1734 update_call_expr_flags (tree call
)
1736 tree decl
= get_callee_fndecl (call
);
1739 if (call_expr_flags (call
) & (ECF_CONST
| ECF_PURE
))
1740 TREE_SIDE_EFFECTS (call
) = 0;
1741 if (TREE_NOTHROW (decl
))
1742 TREE_NOTHROW (call
) = 1;
1746 /* T is CALL_EXPR. Set current_function_calls_* flags. */
1749 notice_special_calls (tree t
)
1751 int flags
= call_expr_flags (t
);
1753 if (flags
& ECF_MAY_BE_ALLOCA
)
1754 current_function_calls_alloca
= true;
1755 if (flags
& ECF_RETURNS_TWICE
)
1756 current_function_calls_setjmp
= true;
1760 /* Clear flags set by notice_special_calls. Used by dead code removal
1761 to update the flags. */
1764 clear_special_calls (void)
1766 current_function_calls_alloca
= false;
1767 current_function_calls_setjmp
= false;
1772 remove_useless_stmts_1 (tree
*tp
, struct rus_data
*data
)
1776 switch (TREE_CODE (t
))
1779 remove_useless_stmts_cond (tp
, data
);
1782 case TRY_FINALLY_EXPR
:
1783 remove_useless_stmts_tf (tp
, data
);
1786 case TRY_CATCH_EXPR
:
1787 remove_useless_stmts_tc (tp
, data
);
1791 remove_useless_stmts_bind (tp
, data
);
1795 remove_useless_stmts_goto (tp
, data
);
1799 remove_useless_stmts_label (tp
, data
);
1804 data
->last_goto
= NULL
;
1805 data
->may_branch
= true;
1810 data
->last_goto
= NULL
;
1811 notice_special_calls (t
);
1812 update_call_expr_flags (t
);
1813 if (tree_could_throw_p (t
))
1814 data
->may_throw
= true;
1818 data
->last_goto
= NULL
;
1820 op
= get_call_expr_in (t
);
1823 update_call_expr_flags (op
);
1824 notice_special_calls (op
);
1826 if (tree_could_throw_p (t
))
1827 data
->may_throw
= true;
1830 case STATEMENT_LIST
:
1832 tree_stmt_iterator i
= tsi_start (t
);
1833 while (!tsi_end_p (i
))
1836 if (IS_EMPTY_STMT (t
))
1842 remove_useless_stmts_1 (tsi_stmt_ptr (i
), data
);
1845 if (TREE_CODE (t
) == STATEMENT_LIST
)
1847 tsi_link_before (&i
, t
, TSI_SAME_STMT
);
1857 data
->last_goto
= NULL
;
1861 data
->last_goto
= NULL
;
1867 remove_useless_stmts (void)
1869 struct rus_data data
;
1871 clear_special_calls ();
1875 memset (&data
, 0, sizeof (data
));
1876 remove_useless_stmts_1 (&DECL_SAVED_TREE (current_function_decl
), &data
);
1878 while (data
.repeat
);
1882 struct tree_opt_pass pass_remove_useless_stmts
=
1884 "useless", /* name */
1886 remove_useless_stmts
, /* execute */
1889 0, /* static_pass_number */
1891 PROP_gimple_any
, /* properties_required */
1892 0, /* properties_provided */
1893 0, /* properties_destroyed */
1894 0, /* todo_flags_start */
1895 TODO_dump_func
, /* todo_flags_finish */
1899 /* Remove PHI nodes associated with basic block BB and all edges out of BB. */
1902 remove_phi_nodes_and_edges_for_unreachable_block (basic_block bb
)
1906 /* Since this block is no longer reachable, we can just delete all
1907 of its PHI nodes. */
1908 phi
= phi_nodes (bb
);
1911 tree next
= PHI_CHAIN (phi
);
1912 remove_phi_node (phi
, NULL_TREE
);
1916 /* Remove edges to BB's successors. */
1917 while (EDGE_COUNT (bb
->succs
) > 0)
1918 remove_edge (EDGE_SUCC (bb
, 0));
1922 /* Remove statements of basic block BB. */
1925 remove_bb (basic_block bb
)
1927 block_stmt_iterator i
;
1928 #ifdef USE_MAPPED_LOCATION
1929 source_location loc
= UNKNOWN_LOCATION
;
1931 source_locus loc
= 0;
1936 fprintf (dump_file
, "Removing basic block %d\n", bb
->index
);
1937 if (dump_flags
& TDF_DETAILS
)
1939 dump_bb (bb
, dump_file
, 0);
1940 fprintf (dump_file
, "\n");
1944 /* If we remove the header or the latch of a loop, mark the loop for
1945 removal by setting its header and latch to NULL. */
1948 struct loop
*loop
= bb
->loop_father
;
1950 if (loop
->latch
== bb
1951 || loop
->header
== bb
)
1954 loop
->header
= NULL
;
1958 /* Remove all the instructions in the block. */
1959 for (i
= bsi_start (bb
); !bsi_end_p (i
);)
1961 tree stmt
= bsi_stmt (i
);
1962 if (TREE_CODE (stmt
) == LABEL_EXPR
1963 && FORCED_LABEL (LABEL_EXPR_LABEL (stmt
)))
1965 basic_block new_bb
= bb
->prev_bb
;
1966 block_stmt_iterator new_bsi
= bsi_start (new_bb
);
1969 bsi_insert_before (&new_bsi
, stmt
, BSI_NEW_STMT
);
1973 release_defs (stmt
);
1978 /* Don't warn for removed gotos. Gotos are often removed due to
1979 jump threading, thus resulting in bogus warnings. Not great,
1980 since this way we lose warnings for gotos in the original
1981 program that are indeed unreachable. */
1982 if (TREE_CODE (stmt
) != GOTO_EXPR
&& EXPR_HAS_LOCATION (stmt
) && !loc
)
1984 #ifdef USE_MAPPED_LOCATION
1985 if (EXPR_HAS_LOCATION (stmt
))
1986 loc
= EXPR_LOCATION (stmt
);
1989 t
= EXPR_LOCUS (stmt
);
1990 if (t
&& LOCATION_LINE (*t
) > 0)
1996 /* If requested, give a warning that the first statement in the
1997 block is unreachable. We walk statements backwards in the
1998 loop above, so the last statement we process is the first statement
2000 #ifdef USE_MAPPED_LOCATION
2001 if (loc
> BUILTINS_LOCATION
)
2002 warning (OPT_Wunreachable_code
, "%Hwill never be executed", &loc
);
2005 warning (OPT_Wunreachable_code
, "%Hwill never be executed", loc
);
2008 remove_phi_nodes_and_edges_for_unreachable_block (bb
);
2012 /* Given a basic block BB ending with COND_EXPR or SWITCH_EXPR, and a
2013 predicate VAL, return the edge that will be taken out of the block.
2014 If VAL does not match a unique edge, NULL is returned. */
2017 find_taken_edge (basic_block bb
, tree val
)
2021 stmt
= last_stmt (bb
);
2024 gcc_assert (is_ctrl_stmt (stmt
));
2027 if (! is_gimple_min_invariant (val
))
2030 if (TREE_CODE (stmt
) == COND_EXPR
)
2031 return find_taken_edge_cond_expr (bb
, val
);
2033 if (TREE_CODE (stmt
) == SWITCH_EXPR
)
2034 return find_taken_edge_switch_expr (bb
, val
);
2036 if (computed_goto_p (stmt
))
2037 return find_taken_edge_computed_goto (bb
, TREE_OPERAND( val
, 0));
2042 /* Given a constant value VAL and the entry block BB to a GOTO_EXPR
2043 statement, determine which of the outgoing edges will be taken out of the
2044 block. Return NULL if either edge may be taken. */
2047 find_taken_edge_computed_goto (basic_block bb
, tree val
)
2052 dest
= label_to_block (val
);
2055 e
= find_edge (bb
, dest
);
2056 gcc_assert (e
!= NULL
);
2062 /* Given a constant value VAL and the entry block BB to a COND_EXPR
2063 statement, determine which of the two edges will be taken out of the
2064 block. Return NULL if either edge may be taken. */
2067 find_taken_edge_cond_expr (basic_block bb
, tree val
)
2069 edge true_edge
, false_edge
;
2071 extract_true_false_edges_from_block (bb
, &true_edge
, &false_edge
);
2073 gcc_assert (TREE_CODE (val
) == INTEGER_CST
);
2074 return (zero_p (val
) ? false_edge
: true_edge
);
2077 /* Given an INTEGER_CST VAL and the entry block BB to a SWITCH_EXPR
2078 statement, determine which edge will be taken out of the block. Return
2079 NULL if any edge may be taken. */
2082 find_taken_edge_switch_expr (basic_block bb
, tree val
)
2084 tree switch_expr
, taken_case
;
2085 basic_block dest_bb
;
2088 switch_expr
= last_stmt (bb
);
2089 taken_case
= find_case_label_for_value (switch_expr
, val
);
2090 dest_bb
= label_to_block (CASE_LABEL (taken_case
));
2092 e
= find_edge (bb
, dest_bb
);
2098 /* Return the CASE_LABEL_EXPR that SWITCH_EXPR will take for VAL.
2099 We can make optimal use here of the fact that the case labels are
2100 sorted: We can do a binary search for a case matching VAL. */
2103 find_case_label_for_value (tree switch_expr
, tree val
)
2105 tree vec
= SWITCH_LABELS (switch_expr
);
2106 size_t low
, high
, n
= TREE_VEC_LENGTH (vec
);
2107 tree default_case
= TREE_VEC_ELT (vec
, n
- 1);
2109 for (low
= -1, high
= n
- 1; high
- low
> 1; )
2111 size_t i
= (high
+ low
) / 2;
2112 tree t
= TREE_VEC_ELT (vec
, i
);
2115 /* Cache the result of comparing CASE_LOW and val. */
2116 cmp
= tree_int_cst_compare (CASE_LOW (t
), val
);
2123 if (CASE_HIGH (t
) == NULL
)
2125 /* A singe-valued case label. */
2131 /* A case range. We can only handle integer ranges. */
2132 if (cmp
<= 0 && tree_int_cst_compare (CASE_HIGH (t
), val
) >= 0)
2137 return default_case
;
2143 /*---------------------------------------------------------------------------
2145 ---------------------------------------------------------------------------*/
2147 /* Dump tree-specific information of block BB to file OUTF. */
2150 tree_dump_bb (basic_block bb
, FILE *outf
, int indent
)
2152 dump_generic_bb (outf
, bb
, indent
, TDF_VOPS
);
2156 /* Dump a basic block on stderr. */
2159 debug_tree_bb (basic_block bb
)
2161 dump_bb (bb
, stderr
, 0);
2165 /* Dump basic block with index N on stderr. */
2168 debug_tree_bb_n (int n
)
2170 debug_tree_bb (BASIC_BLOCK (n
));
2171 return BASIC_BLOCK (n
);
2175 /* Dump the CFG on stderr.
2177 FLAGS are the same used by the tree dumping functions
2178 (see TDF_* in tree.h). */
2181 debug_tree_cfg (int flags
)
2183 dump_tree_cfg (stderr
, flags
);
2187 /* Dump the program showing basic block boundaries on the given FILE.
2189 FLAGS are the same used by the tree dumping functions (see TDF_* in
2193 dump_tree_cfg (FILE *file
, int flags
)
2195 if (flags
& TDF_DETAILS
)
2197 const char *funcname
2198 = lang_hooks
.decl_printable_name (current_function_decl
, 2);
2201 fprintf (file
, ";; Function %s\n\n", funcname
);
2202 fprintf (file
, ";; \n%d basic blocks, %d edges, last basic block %d.\n\n",
2203 n_basic_blocks
, n_edges
, last_basic_block
);
2205 brief_dump_cfg (file
);
2206 fprintf (file
, "\n");
2209 if (flags
& TDF_STATS
)
2210 dump_cfg_stats (file
);
2212 dump_function_to_file (current_function_decl
, file
, flags
| TDF_BLOCKS
);
2216 /* Dump CFG statistics on FILE. */
2219 dump_cfg_stats (FILE *file
)
2221 static long max_num_merged_labels
= 0;
2222 unsigned long size
, total
= 0;
2225 const char * const fmt_str
= "%-30s%-13s%12s\n";
2226 const char * const fmt_str_1
= "%-30s%13d%11lu%c\n";
2227 const char * const fmt_str_3
= "%-43s%11lu%c\n";
2228 const char *funcname
2229 = lang_hooks
.decl_printable_name (current_function_decl
, 2);
2232 fprintf (file
, "\nCFG Statistics for %s\n\n", funcname
);
2234 fprintf (file
, "---------------------------------------------------------\n");
2235 fprintf (file
, fmt_str
, "", " Number of ", "Memory");
2236 fprintf (file
, fmt_str
, "", " instances ", "used ");
2237 fprintf (file
, "---------------------------------------------------------\n");
2239 size
= n_basic_blocks
* sizeof (struct basic_block_def
);
2241 fprintf (file
, fmt_str_1
, "Basic blocks", n_basic_blocks
,
2242 SCALE (size
), LABEL (size
));
2246 num_edges
+= EDGE_COUNT (bb
->succs
);
2247 size
= num_edges
* sizeof (struct edge_def
);
2249 fprintf (file
, fmt_str_1
, "Edges", num_edges
, SCALE (size
), LABEL (size
));
2251 fprintf (file
, "---------------------------------------------------------\n");
2252 fprintf (file
, fmt_str_3
, "Total memory used by CFG data", SCALE (total
),
2254 fprintf (file
, "---------------------------------------------------------\n");
2255 fprintf (file
, "\n");
2257 if (cfg_stats
.num_merged_labels
> max_num_merged_labels
)
2258 max_num_merged_labels
= cfg_stats
.num_merged_labels
;
2260 fprintf (file
, "Coalesced label blocks: %ld (Max so far: %ld)\n",
2261 cfg_stats
.num_merged_labels
, max_num_merged_labels
);
2263 fprintf (file
, "\n");
2267 /* Dump CFG statistics on stderr. Keep extern so that it's always
2268 linked in the final executable. */
2271 debug_cfg_stats (void)
2273 dump_cfg_stats (stderr
);
2277 /* Dump the flowgraph to a .vcg FILE. */
2280 tree_cfg2vcg (FILE *file
)
2285 const char *funcname
2286 = lang_hooks
.decl_printable_name (current_function_decl
, 2);
2288 /* Write the file header. */
2289 fprintf (file
, "graph: { title: \"%s\"\n", funcname
);
2290 fprintf (file
, "node: { title: \"ENTRY\" label: \"ENTRY\" }\n");
2291 fprintf (file
, "node: { title: \"EXIT\" label: \"EXIT\" }\n");
2293 /* Write blocks and edges. */
2294 FOR_EACH_EDGE (e
, ei
, ENTRY_BLOCK_PTR
->succs
)
2296 fprintf (file
, "edge: { sourcename: \"ENTRY\" targetname: \"%d\"",
2299 if (e
->flags
& EDGE_FAKE
)
2300 fprintf (file
, " linestyle: dotted priority: 10");
2302 fprintf (file
, " linestyle: solid priority: 100");
2304 fprintf (file
, " }\n");
2310 enum tree_code head_code
, end_code
;
2311 const char *head_name
, *end_name
;
2314 tree first
= first_stmt (bb
);
2315 tree last
= last_stmt (bb
);
2319 head_code
= TREE_CODE (first
);
2320 head_name
= tree_code_name
[head_code
];
2321 head_line
= get_lineno (first
);
2324 head_name
= "no-statement";
2328 end_code
= TREE_CODE (last
);
2329 end_name
= tree_code_name
[end_code
];
2330 end_line
= get_lineno (last
);
2333 end_name
= "no-statement";
2335 fprintf (file
, "node: { title: \"%d\" label: \"#%d\\n%s (%d)\\n%s (%d)\"}\n",
2336 bb
->index
, bb
->index
, head_name
, head_line
, end_name
,
2339 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
2341 if (e
->dest
== EXIT_BLOCK_PTR
)
2342 fprintf (file
, "edge: { sourcename: \"%d\" targetname: \"EXIT\"", bb
->index
);
2344 fprintf (file
, "edge: { sourcename: \"%d\" targetname: \"%d\"", bb
->index
, e
->dest
->index
);
2346 if (e
->flags
& EDGE_FAKE
)
2347 fprintf (file
, " priority: 10 linestyle: dotted");
2349 fprintf (file
, " priority: 100 linestyle: solid");
2351 fprintf (file
, " }\n");
2354 if (bb
->next_bb
!= EXIT_BLOCK_PTR
)
2358 fputs ("}\n\n", file
);
2363 /*---------------------------------------------------------------------------
2364 Miscellaneous helpers
2365 ---------------------------------------------------------------------------*/
2367 /* Return true if T represents a stmt that always transfers control. */
2370 is_ctrl_stmt (tree t
)
2372 return (TREE_CODE (t
) == COND_EXPR
2373 || TREE_CODE (t
) == SWITCH_EXPR
2374 || TREE_CODE (t
) == GOTO_EXPR
2375 || TREE_CODE (t
) == RETURN_EXPR
2376 || TREE_CODE (t
) == RESX_EXPR
);
2380 /* Return true if T is a statement that may alter the flow of control
2381 (e.g., a call to a non-returning function). */
2384 is_ctrl_altering_stmt (tree t
)
2389 call
= get_call_expr_in (t
);
2392 /* A non-pure/const CALL_EXPR alters flow control if the current
2393 function has nonlocal labels. */
2394 if (TREE_SIDE_EFFECTS (call
) && current_function_has_nonlocal_label
)
2397 /* A CALL_EXPR also alters control flow if it does not return. */
2398 if (call_expr_flags (call
) & ECF_NORETURN
)
2402 /* If a statement can throw, it alters control flow. */
2403 return tree_can_throw_internal (t
);
2407 /* Return true if T is a computed goto. */
2410 computed_goto_p (tree t
)
2412 return (TREE_CODE (t
) == GOTO_EXPR
2413 && TREE_CODE (GOTO_DESTINATION (t
)) != LABEL_DECL
);
2417 /* Checks whether EXPR is a simple local goto. */
2420 simple_goto_p (tree expr
)
2422 return (TREE_CODE (expr
) == GOTO_EXPR
2423 && TREE_CODE (GOTO_DESTINATION (expr
)) == LABEL_DECL
);
2427 /* Return true if T should start a new basic block. PREV_T is the
2428 statement preceding T. It is used when T is a label or a case label.
2429 Labels should only start a new basic block if their previous statement
2430 wasn't a label. Otherwise, sequence of labels would generate
2431 unnecessary basic blocks that only contain a single label. */
2434 stmt_starts_bb_p (tree t
, tree prev_t
)
2439 /* LABEL_EXPRs start a new basic block only if the preceding
2440 statement wasn't a label of the same type. This prevents the
2441 creation of consecutive blocks that have nothing but a single
2443 if (TREE_CODE (t
) == LABEL_EXPR
)
2445 /* Nonlocal and computed GOTO targets always start a new block. */
2446 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (t
))
2447 || FORCED_LABEL (LABEL_EXPR_LABEL (t
)))
2450 if (prev_t
&& TREE_CODE (prev_t
) == LABEL_EXPR
)
2452 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (prev_t
)))
2455 cfg_stats
.num_merged_labels
++;
2466 /* Return true if T should end a basic block. */
2469 stmt_ends_bb_p (tree t
)
2471 return is_ctrl_stmt (t
) || is_ctrl_altering_stmt (t
);
2475 /* Add gotos that used to be represented implicitly in the CFG. */
2478 disband_implicit_edges (void)
2481 block_stmt_iterator last
;
2488 last
= bsi_last (bb
);
2489 stmt
= last_stmt (bb
);
2491 if (stmt
&& TREE_CODE (stmt
) == COND_EXPR
)
2493 /* Remove superfluous gotos from COND_EXPR branches. Moved
2494 from cfg_remove_useless_stmts here since it violates the
2495 invariants for tree--cfg correspondence and thus fits better
2496 here where we do it anyway. */
2497 e
= find_edge (bb
, bb
->next_bb
);
2500 if (e
->flags
& EDGE_TRUE_VALUE
)
2501 COND_EXPR_THEN (stmt
) = build_empty_stmt ();
2502 else if (e
->flags
& EDGE_FALSE_VALUE
)
2503 COND_EXPR_ELSE (stmt
) = build_empty_stmt ();
2506 e
->flags
|= EDGE_FALLTHRU
;
2512 if (stmt
&& TREE_CODE (stmt
) == RETURN_EXPR
)
2514 /* Remove the RETURN_EXPR if we may fall though to the exit
2516 gcc_assert (single_succ_p (bb
));
2517 gcc_assert (single_succ (bb
) == EXIT_BLOCK_PTR
);
2519 if (bb
->next_bb
== EXIT_BLOCK_PTR
2520 && !TREE_OPERAND (stmt
, 0))
2523 single_succ_edge (bb
)->flags
|= EDGE_FALLTHRU
;
2528 /* There can be no fallthru edge if the last statement is a control
2530 if (stmt
&& is_ctrl_stmt (stmt
))
2533 /* Find a fallthru edge and emit the goto if necessary. */
2534 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
2535 if (e
->flags
& EDGE_FALLTHRU
)
2538 if (!e
|| e
->dest
== bb
->next_bb
)
2541 gcc_assert (e
->dest
!= EXIT_BLOCK_PTR
);
2542 label
= tree_block_label (e
->dest
);
2544 stmt
= build1 (GOTO_EXPR
, void_type_node
, label
);
2545 #ifdef USE_MAPPED_LOCATION
2546 SET_EXPR_LOCATION (stmt
, e
->goto_locus
);
2548 SET_EXPR_LOCUS (stmt
, e
->goto_locus
);
2550 bsi_insert_after (&last
, stmt
, BSI_NEW_STMT
);
2551 e
->flags
&= ~EDGE_FALLTHRU
;
2555 /* Remove block annotations and other datastructures. */
2558 delete_tree_cfg_annotations (void)
2562 label_to_block_map
= NULL
;
2568 /* Return the first statement in basic block BB. */
2571 first_stmt (basic_block bb
)
2573 block_stmt_iterator i
= bsi_start (bb
);
2574 return !bsi_end_p (i
) ? bsi_stmt (i
) : NULL_TREE
;
2578 /* Return the last statement in basic block BB. */
2581 last_stmt (basic_block bb
)
2583 block_stmt_iterator b
= bsi_last (bb
);
2584 return !bsi_end_p (b
) ? bsi_stmt (b
) : NULL_TREE
;
2588 /* Return a pointer to the last statement in block BB. */
2591 last_stmt_ptr (basic_block bb
)
2593 block_stmt_iterator last
= bsi_last (bb
);
2594 return !bsi_end_p (last
) ? bsi_stmt_ptr (last
) : NULL
;
2598 /* Return the last statement of an otherwise empty block. Return NULL
2599 if the block is totally empty, or if it contains more than one
2603 last_and_only_stmt (basic_block bb
)
2605 block_stmt_iterator i
= bsi_last (bb
);
2611 last
= bsi_stmt (i
);
2616 /* Empty statements should no longer appear in the instruction stream.
2617 Everything that might have appeared before should be deleted by
2618 remove_useless_stmts, and the optimizers should just bsi_remove
2619 instead of smashing with build_empty_stmt.
2621 Thus the only thing that should appear here in a block containing
2622 one executable statement is a label. */
2623 prev
= bsi_stmt (i
);
2624 if (TREE_CODE (prev
) == LABEL_EXPR
)
2631 /* Mark BB as the basic block holding statement T. */
2634 set_bb_for_stmt (tree t
, basic_block bb
)
2636 if (TREE_CODE (t
) == PHI_NODE
)
2638 else if (TREE_CODE (t
) == STATEMENT_LIST
)
2640 tree_stmt_iterator i
;
2641 for (i
= tsi_start (t
); !tsi_end_p (i
); tsi_next (&i
))
2642 set_bb_for_stmt (tsi_stmt (i
), bb
);
2646 stmt_ann_t ann
= get_stmt_ann (t
);
2649 /* If the statement is a label, add the label to block-to-labels map
2650 so that we can speed up edge creation for GOTO_EXPRs. */
2651 if (TREE_CODE (t
) == LABEL_EXPR
)
2655 t
= LABEL_EXPR_LABEL (t
);
2656 uid
= LABEL_DECL_UID (t
);
2659 LABEL_DECL_UID (t
) = uid
= cfun
->last_label_uid
++;
2660 if (VARRAY_SIZE (label_to_block_map
) <= (unsigned) uid
)
2661 VARRAY_GROW (label_to_block_map
, 3 * uid
/ 2);
2664 /* We're moving an existing label. Make sure that we've
2665 removed it from the old block. */
2666 gcc_assert (!bb
|| !VARRAY_BB (label_to_block_map
, uid
));
2667 VARRAY_BB (label_to_block_map
, uid
) = bb
;
2672 /* Finds iterator for STMT. */
2674 extern block_stmt_iterator
2675 bsi_for_stmt (tree stmt
)
2677 block_stmt_iterator bsi
;
2679 for (bsi
= bsi_start (bb_for_stmt (stmt
)); !bsi_end_p (bsi
); bsi_next (&bsi
))
2680 if (bsi_stmt (bsi
) == stmt
)
2686 /* Mark statement T as modified, and update it. */
2688 update_modified_stmts (tree t
)
2690 if (TREE_CODE (t
) == STATEMENT_LIST
)
2692 tree_stmt_iterator i
;
2694 for (i
= tsi_start (t
); !tsi_end_p (i
); tsi_next (&i
))
2696 stmt
= tsi_stmt (i
);
2697 update_stmt_if_modified (stmt
);
2701 update_stmt_if_modified (t
);
2704 /* Insert statement (or statement list) T before the statement
2705 pointed-to by iterator I. M specifies how to update iterator I
2706 after insertion (see enum bsi_iterator_update). */
2709 bsi_insert_before (block_stmt_iterator
*i
, tree t
, enum bsi_iterator_update m
)
2711 set_bb_for_stmt (t
, i
->bb
);
2712 update_modified_stmts (t
);
2713 tsi_link_before (&i
->tsi
, t
, m
);
2717 /* Insert statement (or statement list) T after the statement
2718 pointed-to by iterator I. M specifies how to update iterator I
2719 after insertion (see enum bsi_iterator_update). */
2722 bsi_insert_after (block_stmt_iterator
*i
, tree t
, enum bsi_iterator_update m
)
2724 set_bb_for_stmt (t
, i
->bb
);
2725 update_modified_stmts (t
);
2726 tsi_link_after (&i
->tsi
, t
, m
);
2730 /* Remove the statement pointed to by iterator I. The iterator is updated
2731 to the next statement. */
2734 bsi_remove (block_stmt_iterator
*i
)
2736 tree t
= bsi_stmt (*i
);
2737 set_bb_for_stmt (t
, NULL
);
2738 delink_stmt_imm_use (t
);
2739 tsi_delink (&i
->tsi
);
2740 mark_stmt_modified (t
);
2744 /* Move the statement at FROM so it comes right after the statement at TO. */
2747 bsi_move_after (block_stmt_iterator
*from
, block_stmt_iterator
*to
)
2749 tree stmt
= bsi_stmt (*from
);
2751 bsi_insert_after (to
, stmt
, BSI_SAME_STMT
);
2755 /* Move the statement at FROM so it comes right before the statement at TO. */
2758 bsi_move_before (block_stmt_iterator
*from
, block_stmt_iterator
*to
)
2760 tree stmt
= bsi_stmt (*from
);
2762 bsi_insert_before (to
, stmt
, BSI_SAME_STMT
);
2766 /* Move the statement at FROM to the end of basic block BB. */
2769 bsi_move_to_bb_end (block_stmt_iterator
*from
, basic_block bb
)
2771 block_stmt_iterator last
= bsi_last (bb
);
2773 /* Have to check bsi_end_p because it could be an empty block. */
2774 if (!bsi_end_p (last
) && is_ctrl_stmt (bsi_stmt (last
)))
2775 bsi_move_before (from
, &last
);
2777 bsi_move_after (from
, &last
);
2781 /* Replace the contents of the statement pointed to by iterator BSI
2782 with STMT. If PRESERVE_EH_INFO is true, the exception handling
2783 information of the original statement is preserved. */
2786 bsi_replace (const block_stmt_iterator
*bsi
, tree stmt
, bool preserve_eh_info
)
2789 tree orig_stmt
= bsi_stmt (*bsi
);
2791 SET_EXPR_LOCUS (stmt
, EXPR_LOCUS (orig_stmt
));
2792 set_bb_for_stmt (stmt
, bsi
->bb
);
2794 /* Preserve EH region information from the original statement, if
2795 requested by the caller. */
2796 if (preserve_eh_info
)
2798 eh_region
= lookup_stmt_eh_region (orig_stmt
);
2800 add_stmt_to_eh_region (stmt
, eh_region
);
2803 delink_stmt_imm_use (orig_stmt
);
2804 *bsi_stmt_ptr (*bsi
) = stmt
;
2805 mark_stmt_modified (stmt
);
2806 update_modified_stmts (stmt
);
2810 /* Insert the statement pointed-to by BSI into edge E. Every attempt
2811 is made to place the statement in an existing basic block, but
2812 sometimes that isn't possible. When it isn't possible, the edge is
2813 split and the statement is added to the new block.
2815 In all cases, the returned *BSI points to the correct location. The
2816 return value is true if insertion should be done after the location,
2817 or false if it should be done before the location. If new basic block
2818 has to be created, it is stored in *NEW_BB. */
2821 tree_find_edge_insert_loc (edge e
, block_stmt_iterator
*bsi
,
2822 basic_block
*new_bb
)
2824 basic_block dest
, src
;
2830 /* If the destination has one predecessor which has no PHI nodes,
2831 insert there. Except for the exit block.
2833 The requirement for no PHI nodes could be relaxed. Basically we
2834 would have to examine the PHIs to prove that none of them used
2835 the value set by the statement we want to insert on E. That
2836 hardly seems worth the effort. */
2837 if (single_pred_p (dest
)
2838 && ! phi_nodes (dest
)
2839 && dest
!= EXIT_BLOCK_PTR
)
2841 *bsi
= bsi_start (dest
);
2842 if (bsi_end_p (*bsi
))
2845 /* Make sure we insert after any leading labels. */
2846 tmp
= bsi_stmt (*bsi
);
2847 while (TREE_CODE (tmp
) == LABEL_EXPR
)
2850 if (bsi_end_p (*bsi
))
2852 tmp
= bsi_stmt (*bsi
);
2855 if (bsi_end_p (*bsi
))
2857 *bsi
= bsi_last (dest
);
2864 /* If the source has one successor, the edge is not abnormal and
2865 the last statement does not end a basic block, insert there.
2866 Except for the entry block. */
2868 if ((e
->flags
& EDGE_ABNORMAL
) == 0
2869 && single_succ_p (src
)
2870 && src
!= ENTRY_BLOCK_PTR
)
2872 *bsi
= bsi_last (src
);
2873 if (bsi_end_p (*bsi
))
2876 tmp
= bsi_stmt (*bsi
);
2877 if (!stmt_ends_bb_p (tmp
))
2880 /* Insert code just before returning the value. We may need to decompose
2881 the return in the case it contains non-trivial operand. */
2882 if (TREE_CODE (tmp
) == RETURN_EXPR
)
2884 tree op
= TREE_OPERAND (tmp
, 0);
2885 if (!is_gimple_val (op
))
2887 gcc_assert (TREE_CODE (op
) == MODIFY_EXPR
);
2888 bsi_insert_before (bsi
, op
, BSI_NEW_STMT
);
2889 TREE_OPERAND (tmp
, 0) = TREE_OPERAND (op
, 0);
2896 /* Otherwise, create a new basic block, and split this edge. */
2897 dest
= split_edge (e
);
2900 e
= single_pred_edge (dest
);
2905 /* This routine will commit all pending edge insertions, creating any new
2906 basic blocks which are necessary. */
2909 bsi_commit_edge_inserts (void)
2915 bsi_commit_one_edge_insert (single_succ_edge (ENTRY_BLOCK_PTR
), NULL
);
2918 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
2919 bsi_commit_one_edge_insert (e
, NULL
);
2923 /* Commit insertions pending at edge E. If a new block is created, set NEW_BB
2924 to this block, otherwise set it to NULL. */
2927 bsi_commit_one_edge_insert (edge e
, basic_block
*new_bb
)
2931 if (PENDING_STMT (e
))
2933 block_stmt_iterator bsi
;
2934 tree stmt
= PENDING_STMT (e
);
2936 PENDING_STMT (e
) = NULL_TREE
;
2938 if (tree_find_edge_insert_loc (e
, &bsi
, new_bb
))
2939 bsi_insert_after (&bsi
, stmt
, BSI_NEW_STMT
);
2941 bsi_insert_before (&bsi
, stmt
, BSI_NEW_STMT
);
2946 /* Add STMT to the pending list of edge E. No actual insertion is
2947 made until a call to bsi_commit_edge_inserts () is made. */
2950 bsi_insert_on_edge (edge e
, tree stmt
)
2952 append_to_statement_list (stmt
, &PENDING_STMT (e
));
2955 /* Similar to bsi_insert_on_edge+bsi_commit_edge_inserts. If a new
2956 block has to be created, it is returned. */
2959 bsi_insert_on_edge_immediate (edge e
, tree stmt
)
2961 block_stmt_iterator bsi
;
2962 basic_block new_bb
= NULL
;
2964 gcc_assert (!PENDING_STMT (e
));
2966 if (tree_find_edge_insert_loc (e
, &bsi
, &new_bb
))
2967 bsi_insert_after (&bsi
, stmt
, BSI_NEW_STMT
);
2969 bsi_insert_before (&bsi
, stmt
, BSI_NEW_STMT
);
2974 /*---------------------------------------------------------------------------
2975 Tree specific functions for CFG manipulation
2976 ---------------------------------------------------------------------------*/
2978 /* Reinstall those PHI arguments queued in OLD_EDGE to NEW_EDGE. */
2981 reinstall_phi_args (edge new_edge
, edge old_edge
)
2985 if (!PENDING_STMT (old_edge
))
2988 for (var
= PENDING_STMT (old_edge
), phi
= phi_nodes (new_edge
->dest
);
2990 var
= TREE_CHAIN (var
), phi
= PHI_CHAIN (phi
))
2992 tree result
= TREE_PURPOSE (var
);
2993 tree arg
= TREE_VALUE (var
);
2995 gcc_assert (result
== PHI_RESULT (phi
));
2997 add_phi_arg (phi
, arg
, new_edge
);
3000 PENDING_STMT (old_edge
) = NULL
;
3003 /* Split a (typically critical) edge EDGE_IN. Return the new block.
3004 Abort on abnormal edges. */
3007 tree_split_edge (edge edge_in
)
3009 basic_block new_bb
, after_bb
, dest
, src
;
3012 /* Abnormal edges cannot be split. */
3013 gcc_assert (!(edge_in
->flags
& EDGE_ABNORMAL
));
3016 dest
= edge_in
->dest
;
3018 /* Place the new block in the block list. Try to keep the new block
3019 near its "logical" location. This is of most help to humans looking
3020 at debugging dumps. */
3021 if (dest
->prev_bb
&& find_edge (dest
->prev_bb
, dest
))
3022 after_bb
= edge_in
->src
;
3024 after_bb
= dest
->prev_bb
;
3026 new_bb
= create_empty_bb (after_bb
);
3027 new_bb
->frequency
= EDGE_FREQUENCY (edge_in
);
3028 new_bb
->count
= edge_in
->count
;
3029 new_edge
= make_edge (new_bb
, dest
, EDGE_FALLTHRU
);
3030 new_edge
->probability
= REG_BR_PROB_BASE
;
3031 new_edge
->count
= edge_in
->count
;
3033 e
= redirect_edge_and_branch (edge_in
, new_bb
);
3035 reinstall_phi_args (new_edge
, e
);
3041 /* Return true when BB has label LABEL in it. */
3044 has_label_p (basic_block bb
, tree label
)
3046 block_stmt_iterator bsi
;
3048 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
3050 tree stmt
= bsi_stmt (bsi
);
3052 if (TREE_CODE (stmt
) != LABEL_EXPR
)
3054 if (LABEL_EXPR_LABEL (stmt
) == label
)
3061 /* Callback for walk_tree, check that all elements with address taken are
3062 properly noticed as such. The DATA is an int* that is 1 if TP was seen
3063 inside a PHI node. */
3066 verify_expr (tree
*tp
, int *walk_subtrees
, void *data ATTRIBUTE_UNUSED
)
3069 bool in_phi
= (data
!= NULL
);
3074 /* Check operand N for being valid GIMPLE and give error MSG if not.
3075 We check for constants explicitly since they are not considered
3076 gimple invariants if they overflowed. */
3077 #define CHECK_OP(N, MSG) \
3078 do { if (!CONSTANT_CLASS_P (TREE_OPERAND (t, N)) \
3079 && !is_gimple_val (TREE_OPERAND (t, N))) \
3080 { error (MSG); return TREE_OPERAND (t, N); }} while (0)
3082 switch (TREE_CODE (t
))
3085 if (SSA_NAME_IN_FREE_LIST (t
))
3087 error ("SSA name in freelist but still referenced");
3093 x
= fold (ASSERT_EXPR_COND (t
));
3094 if (x
== boolean_false_node
)
3096 error ("ASSERT_EXPR with an always-false condition");
3102 x
= TREE_OPERAND (t
, 0);
3103 if (TREE_CODE (x
) == BIT_FIELD_REF
3104 && is_gimple_reg (TREE_OPERAND (x
, 0)))
3106 error ("GIMPLE register modified with BIT_FIELD_REF");
3115 bool old_side_effects
;
3118 bool new_side_effects
;
3120 /* ??? tree-ssa-alias.c may have overlooked dead PHI nodes, missing
3121 dead PHIs that take the address of something. But if the PHI
3122 result is dead, the fact that it takes the address of anything
3123 is irrelevant. Because we can not tell from here if a PHI result
3124 is dead, we just skip this check for PHIs altogether. This means
3125 we may be missing "valid" checks, but what can you do?
3126 This was PR19217. */
3130 old_invariant
= TREE_INVARIANT (t
);
3131 old_constant
= TREE_CONSTANT (t
);
3132 old_side_effects
= TREE_SIDE_EFFECTS (t
);
3134 recompute_tree_invarant_for_addr_expr (t
);
3135 new_invariant
= TREE_INVARIANT (t
);
3136 new_side_effects
= TREE_SIDE_EFFECTS (t
);
3137 new_constant
= TREE_CONSTANT (t
);
3139 if (old_invariant
!= new_invariant
)
3141 error ("invariant not recomputed when ADDR_EXPR changed");
3145 if (old_constant
!= new_constant
)
3147 error ("constant not recomputed when ADDR_EXPR changed");
3150 if (old_side_effects
!= new_side_effects
)
3152 error ("side effects not recomputed when ADDR_EXPR changed");
3156 /* Skip any references (they will be checked when we recurse down the
3157 tree) and ensure that any variable used as a prefix is marked
3159 for (x
= TREE_OPERAND (t
, 0);
3160 handled_component_p (x
);
3161 x
= TREE_OPERAND (x
, 0))
3164 if (TREE_CODE (x
) != VAR_DECL
&& TREE_CODE (x
) != PARM_DECL
)
3166 if (!TREE_ADDRESSABLE (x
))
3168 error ("address taken, but ADDRESSABLE bit not set");
3175 x
= COND_EXPR_COND (t
);
3176 if (TREE_CODE (TREE_TYPE (x
)) != BOOLEAN_TYPE
)
3178 error ("non-boolean used in condition");
3185 case FIX_TRUNC_EXPR
:
3187 case FIX_FLOOR_EXPR
:
3188 case FIX_ROUND_EXPR
:
3193 case NON_LVALUE_EXPR
:
3194 case TRUTH_NOT_EXPR
:
3195 CHECK_OP (0, "Invalid operand to unary operator");
3202 case ARRAY_RANGE_REF
:
3204 case VIEW_CONVERT_EXPR
:
3205 /* We have a nest of references. Verify that each of the operands
3206 that determine where to reference is either a constant or a variable,
3207 verify that the base is valid, and then show we've already checked
3209 while (handled_component_p (t
))
3211 if (TREE_CODE (t
) == COMPONENT_REF
&& TREE_OPERAND (t
, 2))
3212 CHECK_OP (2, "Invalid COMPONENT_REF offset operator");
3213 else if (TREE_CODE (t
) == ARRAY_REF
3214 || TREE_CODE (t
) == ARRAY_RANGE_REF
)
3216 CHECK_OP (1, "Invalid array index.");
3217 if (TREE_OPERAND (t
, 2))
3218 CHECK_OP (2, "Invalid array lower bound.");
3219 if (TREE_OPERAND (t
, 3))
3220 CHECK_OP (3, "Invalid array stride.");
3222 else if (TREE_CODE (t
) == BIT_FIELD_REF
)
3224 CHECK_OP (1, "Invalid operand to BIT_FIELD_REF");
3225 CHECK_OP (2, "Invalid operand to BIT_FIELD_REF");
3228 t
= TREE_OPERAND (t
, 0);
3231 if (!CONSTANT_CLASS_P (t
) && !is_gimple_lvalue (t
))
3233 error ("Invalid reference prefix.");
3245 case UNORDERED_EXPR
:
3256 case TRUNC_DIV_EXPR
:
3258 case FLOOR_DIV_EXPR
:
3259 case ROUND_DIV_EXPR
:
3260 case TRUNC_MOD_EXPR
:
3262 case FLOOR_MOD_EXPR
:
3263 case ROUND_MOD_EXPR
:
3265 case EXACT_DIV_EXPR
:
3275 CHECK_OP (0, "Invalid operand to binary operator");
3276 CHECK_OP (1, "Invalid operand to binary operator");
3288 /* Verify STMT, return true if STMT is not in GIMPLE form.
3289 TODO: Implement type checking. */
3292 verify_stmt (tree stmt
, bool last_in_block
)
3296 if (!is_gimple_stmt (stmt
))
3298 error ("Is not a valid GIMPLE statement.");
3302 addr
= walk_tree (&stmt
, verify_expr
, NULL
, NULL
);
3305 debug_generic_stmt (addr
);
3309 /* If the statement is marked as part of an EH region, then it is
3310 expected that the statement could throw. Verify that when we
3311 have optimizations that simplify statements such that we prove
3312 that they cannot throw, that we update other data structures
3314 if (lookup_stmt_eh_region (stmt
) >= 0)
3316 if (!tree_could_throw_p (stmt
))
3318 error ("Statement marked for throw, but doesn%'t.");
3321 if (!last_in_block
&& tree_can_throw_internal (stmt
))
3323 error ("Statement marked for throw in middle of block.");
3331 debug_generic_stmt (stmt
);
3336 /* Return true when the T can be shared. */
3339 tree_node_can_be_shared (tree t
)
3341 if (IS_TYPE_OR_DECL_P (t
)
3342 /* We check for constants explicitly since they are not considered
3343 gimple invariants if they overflowed. */
3344 || CONSTANT_CLASS_P (t
)
3345 || is_gimple_min_invariant (t
)
3346 || TREE_CODE (t
) == SSA_NAME
3347 || t
== error_mark_node
)
3350 if (TREE_CODE (t
) == CASE_LABEL_EXPR
)
3353 while (((TREE_CODE (t
) == ARRAY_REF
|| TREE_CODE (t
) == ARRAY_RANGE_REF
)
3354 /* We check for constants explicitly since they are not considered
3355 gimple invariants if they overflowed. */
3356 && (CONSTANT_CLASS_P (TREE_OPERAND (t
, 1))
3357 || is_gimple_min_invariant (TREE_OPERAND (t
, 1))))
3358 || (TREE_CODE (t
) == COMPONENT_REF
3359 || TREE_CODE (t
) == REALPART_EXPR
3360 || TREE_CODE (t
) == IMAGPART_EXPR
))
3361 t
= TREE_OPERAND (t
, 0);
3370 /* Called via walk_trees. Verify tree sharing. */
3373 verify_node_sharing (tree
* tp
, int *walk_subtrees
, void *data
)
3375 htab_t htab
= (htab_t
) data
;
3378 if (tree_node_can_be_shared (*tp
))
3380 *walk_subtrees
= false;
3384 slot
= htab_find_slot (htab
, *tp
, INSERT
);
3393 /* Verify the GIMPLE statement chain. */
3399 block_stmt_iterator bsi
;
3404 timevar_push (TV_TREE_STMT_VERIFY
);
3405 htab
= htab_create (37, htab_hash_pointer
, htab_eq_pointer
, NULL
);
3412 for (phi
= phi_nodes (bb
); phi
; phi
= PHI_CHAIN (phi
))
3414 int phi_num_args
= PHI_NUM_ARGS (phi
);
3416 if (bb_for_stmt (phi
) != bb
)
3418 error ("bb_for_stmt (phi) is set to a wrong basic block\n");
3422 for (i
= 0; i
< phi_num_args
; i
++)
3424 tree t
= PHI_ARG_DEF (phi
, i
);
3427 /* Addressable variables do have SSA_NAMEs but they
3428 are not considered gimple values. */
3429 if (TREE_CODE (t
) != SSA_NAME
3430 && TREE_CODE (t
) != FUNCTION_DECL
3431 && !is_gimple_val (t
))
3433 error ("PHI def is not a GIMPLE value");
3434 debug_generic_stmt (phi
);
3435 debug_generic_stmt (t
);
3439 addr
= walk_tree (&t
, verify_expr
, (void *) 1, NULL
);
3442 debug_generic_stmt (addr
);
3446 addr
= walk_tree (&t
, verify_node_sharing
, htab
, NULL
);
3449 error ("Incorrect sharing of tree nodes");
3450 debug_generic_stmt (phi
);
3451 debug_generic_stmt (addr
);
3457 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); )
3459 tree stmt
= bsi_stmt (bsi
);
3461 if (bb_for_stmt (stmt
) != bb
)
3463 error ("bb_for_stmt (stmt) is set to a wrong basic block\n");
3468 err
|= verify_stmt (stmt
, bsi_end_p (bsi
));
3469 addr
= walk_tree (&stmt
, verify_node_sharing
, htab
, NULL
);
3472 error ("Incorrect sharing of tree nodes");
3473 debug_generic_stmt (stmt
);
3474 debug_generic_stmt (addr
);
3481 internal_error ("verify_stmts failed.");
3484 timevar_pop (TV_TREE_STMT_VERIFY
);
3488 /* Verifies that the flow information is OK. */
3491 tree_verify_flow_info (void)
3495 block_stmt_iterator bsi
;
3500 if (ENTRY_BLOCK_PTR
->stmt_list
)
3502 error ("ENTRY_BLOCK has a statement list associated with it\n");
3506 if (EXIT_BLOCK_PTR
->stmt_list
)
3508 error ("EXIT_BLOCK has a statement list associated with it\n");
3512 FOR_EACH_EDGE (e
, ei
, EXIT_BLOCK_PTR
->preds
)
3513 if (e
->flags
& EDGE_FALLTHRU
)
3515 error ("Fallthru to exit from bb %d\n", e
->src
->index
);
3521 bool found_ctrl_stmt
= false;
3525 /* Skip labels on the start of basic block. */
3526 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
3528 tree prev_stmt
= stmt
;
3530 stmt
= bsi_stmt (bsi
);
3532 if (TREE_CODE (stmt
) != LABEL_EXPR
)
3535 if (prev_stmt
&& DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt
)))
3537 error ("Nonlocal label %s is not first "
3538 "in a sequence of labels in bb %d",
3539 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt
))),
3544 if (label_to_block (LABEL_EXPR_LABEL (stmt
)) != bb
)
3546 error ("Label %s to block does not match in bb %d\n",
3547 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt
))),
3552 if (decl_function_context (LABEL_EXPR_LABEL (stmt
))
3553 != current_function_decl
)
3555 error ("Label %s has incorrect context in bb %d\n",
3556 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt
))),
3562 /* Verify that body of basic block BB is free of control flow. */
3563 for (; !bsi_end_p (bsi
); bsi_next (&bsi
))
3565 tree stmt
= bsi_stmt (bsi
);
3567 if (found_ctrl_stmt
)
3569 error ("Control flow in the middle of basic block %d\n",
3574 if (stmt_ends_bb_p (stmt
))
3575 found_ctrl_stmt
= true;
3577 if (TREE_CODE (stmt
) == LABEL_EXPR
)
3579 error ("Label %s in the middle of basic block %d\n",
3580 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt
))),
3585 bsi
= bsi_last (bb
);
3586 if (bsi_end_p (bsi
))
3589 stmt
= bsi_stmt (bsi
);
3591 err
|= verify_eh_edges (stmt
);
3593 if (is_ctrl_stmt (stmt
))
3595 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
3596 if (e
->flags
& EDGE_FALLTHRU
)
3598 error ("Fallthru edge after a control statement in bb %d \n",
3604 switch (TREE_CODE (stmt
))
3610 if (TREE_CODE (COND_EXPR_THEN (stmt
)) != GOTO_EXPR
3611 || TREE_CODE (COND_EXPR_ELSE (stmt
)) != GOTO_EXPR
)
3613 error ("Structured COND_EXPR at the end of bb %d\n", bb
->index
);
3617 extract_true_false_edges_from_block (bb
, &true_edge
, &false_edge
);
3619 if (!true_edge
|| !false_edge
3620 || !(true_edge
->flags
& EDGE_TRUE_VALUE
)
3621 || !(false_edge
->flags
& EDGE_FALSE_VALUE
)
3622 || (true_edge
->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
))
3623 || (false_edge
->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
))
3624 || EDGE_COUNT (bb
->succs
) >= 3)
3626 error ("Wrong outgoing edge flags at end of bb %d\n",
3631 if (!has_label_p (true_edge
->dest
,
3632 GOTO_DESTINATION (COND_EXPR_THEN (stmt
))))
3634 error ("%<then%> label does not match edge at end of bb %d\n",
3639 if (!has_label_p (false_edge
->dest
,
3640 GOTO_DESTINATION (COND_EXPR_ELSE (stmt
))))
3642 error ("%<else%> label does not match edge at end of bb %d\n",
3650 if (simple_goto_p (stmt
))
3652 error ("Explicit goto at end of bb %d\n", bb
->index
);
3657 /* FIXME. We should double check that the labels in the
3658 destination blocks have their address taken. */
3659 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
3660 if ((e
->flags
& (EDGE_FALLTHRU
| EDGE_TRUE_VALUE
3661 | EDGE_FALSE_VALUE
))
3662 || !(e
->flags
& EDGE_ABNORMAL
))
3664 error ("Wrong outgoing edge flags at end of bb %d\n",
3672 if (!single_succ_p (bb
)
3673 || (single_succ_edge (bb
)->flags
3674 & (EDGE_FALLTHRU
| EDGE_ABNORMAL
3675 | EDGE_TRUE_VALUE
| EDGE_FALSE_VALUE
)))
3677 error ("Wrong outgoing edge flags at end of bb %d\n", bb
->index
);
3680 if (single_succ (bb
) != EXIT_BLOCK_PTR
)
3682 error ("Return edge does not point to exit in bb %d\n",
3695 vec
= SWITCH_LABELS (stmt
);
3696 n
= TREE_VEC_LENGTH (vec
);
3698 /* Mark all the destination basic blocks. */
3699 for (i
= 0; i
< n
; ++i
)
3701 tree lab
= CASE_LABEL (TREE_VEC_ELT (vec
, i
));
3702 basic_block label_bb
= label_to_block (lab
);
3704 gcc_assert (!label_bb
->aux
|| label_bb
->aux
== (void *)1);
3705 label_bb
->aux
= (void *)1;
3708 /* Verify that the case labels are sorted. */
3709 prev
= TREE_VEC_ELT (vec
, 0);
3710 for (i
= 1; i
< n
- 1; ++i
)
3712 tree c
= TREE_VEC_ELT (vec
, i
);
3715 error ("Found default case not at end of case vector");
3719 if (! tree_int_cst_lt (CASE_LOW (prev
), CASE_LOW (c
)))
3721 error ("Case labels not sorted:\n ");
3722 print_generic_expr (stderr
, prev
, 0);
3723 fprintf (stderr
," is greater than ");
3724 print_generic_expr (stderr
, c
, 0);
3725 fprintf (stderr
," but comes before it.\n");
3730 if (CASE_LOW (TREE_VEC_ELT (vec
, n
- 1)))
3732 error ("No default case found at end of case vector");
3736 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
3740 error ("Extra outgoing edge %d->%d\n",
3741 bb
->index
, e
->dest
->index
);
3744 e
->dest
->aux
= (void *)2;
3745 if ((e
->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
3746 | EDGE_TRUE_VALUE
| EDGE_FALSE_VALUE
)))
3748 error ("Wrong outgoing edge flags at end of bb %d\n",
3754 /* Check that we have all of them. */
3755 for (i
= 0; i
< n
; ++i
)
3757 tree lab
= CASE_LABEL (TREE_VEC_ELT (vec
, i
));
3758 basic_block label_bb
= label_to_block (lab
);
3760 if (label_bb
->aux
!= (void *)2)
3762 error ("Missing edge %i->%i",
3763 bb
->index
, label_bb
->index
);
3768 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
3769 e
->dest
->aux
= (void *)0;
3776 if (dom_computed
[CDI_DOMINATORS
] >= DOM_NO_FAST_QUERY
)
3777 verify_dominators (CDI_DOMINATORS
);
3783 /* Updates phi nodes after creating a forwarder block joined
3784 by edge FALLTHRU. */
3787 tree_make_forwarder_block (edge fallthru
)
3791 basic_block dummy
, bb
;
3792 tree phi
, new_phi
, var
;
3794 dummy
= fallthru
->src
;
3795 bb
= fallthru
->dest
;
3797 if (single_pred_p (bb
))
3800 /* If we redirected a branch we must create new phi nodes at the
3802 for (phi
= phi_nodes (dummy
); phi
; phi
= PHI_CHAIN (phi
))
3804 var
= PHI_RESULT (phi
);
3805 new_phi
= create_phi_node (var
, bb
);
3806 SSA_NAME_DEF_STMT (var
) = new_phi
;
3807 SET_PHI_RESULT (phi
, make_ssa_name (SSA_NAME_VAR (var
), phi
));
3808 add_phi_arg (new_phi
, PHI_RESULT (phi
), fallthru
);
3811 /* Ensure that the PHI node chain is in the same order. */
3812 set_phi_nodes (bb
, phi_reverse (phi_nodes (bb
)));
3814 /* Add the arguments we have stored on edges. */
3815 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
3820 flush_pending_stmts (e
);
3825 /* Return a non-special label in the head of basic block BLOCK.
3826 Create one if it doesn't exist. */
3829 tree_block_label (basic_block bb
)
3831 block_stmt_iterator i
, s
= bsi_start (bb
);
3835 for (i
= s
; !bsi_end_p (i
); first
= false, bsi_next (&i
))
3837 stmt
= bsi_stmt (i
);
3838 if (TREE_CODE (stmt
) != LABEL_EXPR
)
3840 label
= LABEL_EXPR_LABEL (stmt
);
3841 if (!DECL_NONLOCAL (label
))
3844 bsi_move_before (&i
, &s
);
3849 label
= create_artificial_label ();
3850 stmt
= build1 (LABEL_EXPR
, void_type_node
, label
);
3851 bsi_insert_before (&s
, stmt
, BSI_NEW_STMT
);
3856 /* Attempt to perform edge redirection by replacing a possibly complex
3857 jump instruction by a goto or by removing the jump completely.
3858 This can apply only if all edges now point to the same block. The
3859 parameters and return values are equivalent to
3860 redirect_edge_and_branch. */
3863 tree_try_redirect_by_replacing_jump (edge e
, basic_block target
)
3865 basic_block src
= e
->src
;
3866 block_stmt_iterator b
;
3869 /* We can replace or remove a complex jump only when we have exactly
3871 if (EDGE_COUNT (src
->succs
) != 2
3872 /* Verify that all targets will be TARGET. Specifically, the
3873 edge that is not E must also go to TARGET. */
3874 || EDGE_SUCC (src
, EDGE_SUCC (src
, 0) == e
)->dest
!= target
)
3880 stmt
= bsi_stmt (b
);
3882 if (TREE_CODE (stmt
) == COND_EXPR
3883 || TREE_CODE (stmt
) == SWITCH_EXPR
)
3886 e
= ssa_redirect_edge (e
, target
);
3887 e
->flags
= EDGE_FALLTHRU
;
3895 /* Redirect E to DEST. Return NULL on failure. Otherwise, return the
3896 edge representing the redirected branch. */
3899 tree_redirect_edge_and_branch (edge e
, basic_block dest
)
3901 basic_block bb
= e
->src
;
3902 block_stmt_iterator bsi
;
3906 if (e
->flags
& (EDGE_ABNORMAL_CALL
| EDGE_EH
))
3909 if (e
->src
!= ENTRY_BLOCK_PTR
3910 && (ret
= tree_try_redirect_by_replacing_jump (e
, dest
)))
3913 if (e
->dest
== dest
)
3916 label
= tree_block_label (dest
);
3918 bsi
= bsi_last (bb
);
3919 stmt
= bsi_end_p (bsi
) ? NULL
: bsi_stmt (bsi
);
3921 switch (stmt
? TREE_CODE (stmt
) : ERROR_MARK
)
3924 stmt
= (e
->flags
& EDGE_TRUE_VALUE
3925 ? COND_EXPR_THEN (stmt
)
3926 : COND_EXPR_ELSE (stmt
));
3927 GOTO_DESTINATION (stmt
) = label
;
3931 /* No non-abnormal edges should lead from a non-simple goto, and
3932 simple ones should be represented implicitly. */
3937 tree cases
= get_cases_for_edge (e
, stmt
);
3939 /* If we have a list of cases associated with E, then use it
3940 as it's a lot faster than walking the entire case vector. */
3943 edge e2
= find_edge (e
->src
, dest
);
3950 CASE_LABEL (cases
) = label
;
3951 cases
= TREE_CHAIN (cases
);
3954 /* If there was already an edge in the CFG, then we need
3955 to move all the cases associated with E to E2. */
3958 tree cases2
= get_cases_for_edge (e2
, stmt
);
3960 TREE_CHAIN (last
) = TREE_CHAIN (cases2
);
3961 TREE_CHAIN (cases2
) = first
;
3966 tree vec
= SWITCH_LABELS (stmt
);
3967 size_t i
, n
= TREE_VEC_LENGTH (vec
);
3969 for (i
= 0; i
< n
; i
++)
3971 tree elt
= TREE_VEC_ELT (vec
, i
);
3973 if (label_to_block (CASE_LABEL (elt
)) == e
->dest
)
3974 CASE_LABEL (elt
) = label
;
3983 e
->flags
|= EDGE_FALLTHRU
;
3987 /* Otherwise it must be a fallthru edge, and we don't need to
3988 do anything besides redirecting it. */
3989 gcc_assert (e
->flags
& EDGE_FALLTHRU
);
3993 /* Update/insert PHI nodes as necessary. */
3995 /* Now update the edges in the CFG. */
3996 e
= ssa_redirect_edge (e
, dest
);
4002 /* Simple wrapper, as we can always redirect fallthru edges. */
4005 tree_redirect_edge_and_branch_force (edge e
, basic_block dest
)
4007 e
= tree_redirect_edge_and_branch (e
, dest
);
4014 /* Splits basic block BB after statement STMT (but at least after the
4015 labels). If STMT is NULL, BB is split just after the labels. */
4018 tree_split_block (basic_block bb
, void *stmt
)
4020 block_stmt_iterator bsi
, bsi_tgt
;
4026 new_bb
= create_empty_bb (bb
);
4028 /* Redirect the outgoing edges. */
4029 new_bb
->succs
= bb
->succs
;
4031 FOR_EACH_EDGE (e
, ei
, new_bb
->succs
)
4034 if (stmt
&& TREE_CODE ((tree
) stmt
) == LABEL_EXPR
)
4037 /* Move everything from BSI to the new basic block. */
4038 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
4040 act
= bsi_stmt (bsi
);
4041 if (TREE_CODE (act
) == LABEL_EXPR
)
4054 bsi_tgt
= bsi_start (new_bb
);
4055 while (!bsi_end_p (bsi
))
4057 act
= bsi_stmt (bsi
);
4059 bsi_insert_after (&bsi_tgt
, act
, BSI_NEW_STMT
);
4066 /* Moves basic block BB after block AFTER. */
4069 tree_move_block_after (basic_block bb
, basic_block after
)
4071 if (bb
->prev_bb
== after
)
4075 link_block (bb
, after
);
4081 /* Return true if basic_block can be duplicated. */
4084 tree_can_duplicate_bb_p (basic_block bb ATTRIBUTE_UNUSED
)
4090 /* Create a duplicate of the basic block BB. NOTE: This does not
4091 preserve SSA form. */
4094 tree_duplicate_bb (basic_block bb
)
4097 block_stmt_iterator bsi
, bsi_tgt
;
4100 new_bb
= create_empty_bb (EXIT_BLOCK_PTR
->prev_bb
);
4102 /* Copy the PHI nodes. We ignore PHI node arguments here because
4103 the incoming edges have not been setup yet. */
4104 for (phi
= phi_nodes (bb
); phi
; phi
= PHI_CHAIN (phi
))
4106 tree copy
= create_phi_node (PHI_RESULT (phi
), new_bb
);
4107 create_new_def_for (PHI_RESULT (copy
), copy
, PHI_RESULT_PTR (copy
));
4110 /* Keep the chain of PHI nodes in the same order so that they can be
4111 updated by ssa_redirect_edge. */
4112 set_phi_nodes (new_bb
, phi_reverse (phi_nodes (new_bb
)));
4114 bsi_tgt
= bsi_start (new_bb
);
4115 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
4117 def_operand_p def_p
;
4118 ssa_op_iter op_iter
;
4122 stmt
= bsi_stmt (bsi
);
4123 if (TREE_CODE (stmt
) == LABEL_EXPR
)
4126 /* Create a new copy of STMT and duplicate STMT's virtual
4128 copy
= unshare_expr (stmt
);
4129 bsi_insert_after (&bsi_tgt
, copy
, BSI_NEW_STMT
);
4130 copy_virtual_operands (copy
, stmt
);
4131 region
= lookup_stmt_eh_region (stmt
);
4133 add_stmt_to_eh_region (copy
, region
);
4135 /* Create new names for all the definitions created by COPY and
4136 add replacement mappings for each new name. */
4137 FOR_EACH_SSA_DEF_OPERAND (def_p
, copy
, op_iter
, SSA_OP_ALL_DEFS
)
4138 create_new_def_for (DEF_FROM_PTR (def_p
), copy
, def_p
);
4145 /* Basic block BB_COPY was created by code duplication. Add phi node
4146 arguments for edges going out of BB_COPY. The blocks that were
4147 duplicated have rbi->duplicated set to one. */
4150 add_phi_args_after_copy_bb (basic_block bb_copy
)
4152 basic_block bb
, dest
;
4155 tree phi
, phi_copy
, phi_next
, def
;
4157 bb
= bb_copy
->rbi
->original
;
4159 FOR_EACH_EDGE (e_copy
, ei
, bb_copy
->succs
)
4161 if (!phi_nodes (e_copy
->dest
))
4164 if (e_copy
->dest
->rbi
->duplicated
)
4165 dest
= e_copy
->dest
->rbi
->original
;
4167 dest
= e_copy
->dest
;
4169 e
= find_edge (bb
, dest
);
4172 /* During loop unrolling the target of the latch edge is copied.
4173 In this case we are not looking for edge to dest, but to
4174 duplicated block whose original was dest. */
4175 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
4176 if (e
->dest
->rbi
->duplicated
4177 && e
->dest
->rbi
->original
== dest
)
4180 gcc_assert (e
!= NULL
);
4183 for (phi
= phi_nodes (e
->dest
), phi_copy
= phi_nodes (e_copy
->dest
);
4185 phi
= phi_next
, phi_copy
= PHI_CHAIN (phi_copy
))
4187 phi_next
= PHI_CHAIN (phi
);
4188 def
= PHI_ARG_DEF_FROM_EDGE (phi
, e
);
4189 add_phi_arg (phi_copy
, def
, e_copy
);
4194 /* Blocks in REGION_COPY array of length N_REGION were created by
4195 duplication of basic blocks. Add phi node arguments for edges
4196 going from these blocks. */
4199 add_phi_args_after_copy (basic_block
*region_copy
, unsigned n_region
)
4203 for (i
= 0; i
< n_region
; i
++)
4204 region_copy
[i
]->rbi
->duplicated
= 1;
4206 for (i
= 0; i
< n_region
; i
++)
4207 add_phi_args_after_copy_bb (region_copy
[i
]);
4209 for (i
= 0; i
< n_region
; i
++)
4210 region_copy
[i
]->rbi
->duplicated
= 0;
4213 /* Duplicates a REGION (set of N_REGION basic blocks) with just a single
4214 important exit edge EXIT. By important we mean that no SSA name defined
4215 inside region is live over the other exit edges of the region. All entry
4216 edges to the region must go to ENTRY->dest. The edge ENTRY is redirected
4217 to the duplicate of the region. SSA form, dominance and loop information
4218 is updated. The new basic blocks are stored to REGION_COPY in the same
4219 order as they had in REGION, provided that REGION_COPY is not NULL.
4220 The function returns false if it is unable to copy the region,
4224 tree_duplicate_sese_region (edge entry
, edge exit
,
4225 basic_block
*region
, unsigned n_region
,
4226 basic_block
*region_copy
)
4229 bool free_region_copy
= false, copying_header
= false;
4230 struct loop
*loop
= entry
->dest
->loop_father
;
4234 int total_freq
, entry_freq
;
4236 if (!can_copy_bbs_p (region
, n_region
))
4239 /* Some sanity checking. Note that we do not check for all possible
4240 missuses of the functions. I.e. if you ask to copy something weird,
4241 it will work, but the state of structures probably will not be
4243 for (i
= 0; i
< n_region
; i
++)
4245 /* We do not handle subloops, i.e. all the blocks must belong to the
4247 if (region
[i
]->loop_father
!= loop
)
4250 if (region
[i
] != entry
->dest
4251 && region
[i
] == loop
->header
)
4257 /* In case the function is used for loop header copying (which is the primary
4258 use), ensure that EXIT and its copy will be new latch and entry edges. */
4259 if (loop
->header
== entry
->dest
)
4261 copying_header
= true;
4262 loop
->copy
= loop
->outer
;
4264 if (!dominated_by_p (CDI_DOMINATORS
, loop
->latch
, exit
->src
))
4267 for (i
= 0; i
< n_region
; i
++)
4268 if (region
[i
] != exit
->src
4269 && dominated_by_p (CDI_DOMINATORS
, region
[i
], exit
->src
))
4275 region_copy
= xmalloc (sizeof (basic_block
) * n_region
);
4276 free_region_copy
= true;
4279 gcc_assert (!need_ssa_update_p ());
4281 /* Record blocks outside the region that are dominated by something
4283 doms
= xmalloc (sizeof (basic_block
) * n_basic_blocks
);
4284 n_doms
= get_dominated_by_region (CDI_DOMINATORS
, region
, n_region
, doms
);
4286 total_freq
= entry
->dest
->frequency
;
4287 entry_freq
= EDGE_FREQUENCY (entry
);
4288 /* Fix up corner cases, to avoid division by zero or creation of negative
4290 if (total_freq
== 0)
4292 else if (entry_freq
> total_freq
)
4293 entry_freq
= total_freq
;
4295 copy_bbs (region
, n_region
, region_copy
, &exit
, 1, &exit_copy
, loop
);
4296 scale_bbs_frequencies_int (region
, n_region
, total_freq
- entry_freq
,
4298 scale_bbs_frequencies_int (region_copy
, n_region
, entry_freq
, total_freq
);
4302 loop
->header
= exit
->dest
;
4303 loop
->latch
= exit
->src
;
4306 /* Redirect the entry and add the phi node arguments. */
4307 redirected
= redirect_edge_and_branch (entry
, entry
->dest
->rbi
->copy
);
4308 gcc_assert (redirected
!= NULL
);
4309 flush_pending_stmts (entry
);
4311 /* Concerning updating of dominators: We must recount dominators
4312 for entry block and its copy. Anything that is outside of the
4313 region, but was dominated by something inside needs recounting as
4315 set_immediate_dominator (CDI_DOMINATORS
, entry
->dest
, entry
->src
);
4316 doms
[n_doms
++] = entry
->dest
->rbi
->original
;
4317 iterate_fix_dominators (CDI_DOMINATORS
, doms
, n_doms
);
4320 /* Add the other PHI node arguments. */
4321 add_phi_args_after_copy (region_copy
, n_region
);
4323 /* Update the SSA web. */
4324 update_ssa (TODO_update_ssa
);
4326 if (free_region_copy
)
4333 /* Dump FUNCTION_DECL FN to file FILE using FLAGS (see TDF_* in tree.h) */
4336 dump_function_to_file (tree fn
, FILE *file
, int flags
)
4338 tree arg
, vars
, var
;
4339 bool ignore_topmost_bind
= false, any_var
= false;
4343 fprintf (file
, "%s (", lang_hooks
.decl_printable_name (fn
, 2));
4345 arg
= DECL_ARGUMENTS (fn
);
4348 print_generic_expr (file
, arg
, dump_flags
);
4349 if (TREE_CHAIN (arg
))
4350 fprintf (file
, ", ");
4351 arg
= TREE_CHAIN (arg
);
4353 fprintf (file
, ")\n");
4355 if (flags
& TDF_DETAILS
)
4356 dump_eh_tree (file
, DECL_STRUCT_FUNCTION (fn
));
4357 if (flags
& TDF_RAW
)
4359 dump_node (fn
, TDF_SLIM
| flags
, file
);
4363 /* When GIMPLE is lowered, the variables are no longer available in
4364 BIND_EXPRs, so display them separately. */
4365 if (cfun
&& cfun
->decl
== fn
&& cfun
->unexpanded_var_list
)
4367 ignore_topmost_bind
= true;
4369 fprintf (file
, "{\n");
4370 for (vars
= cfun
->unexpanded_var_list
; vars
; vars
= TREE_CHAIN (vars
))
4372 var
= TREE_VALUE (vars
);
4374 print_generic_decl (file
, var
, flags
);
4375 fprintf (file
, "\n");
4381 if (cfun
&& cfun
->decl
== fn
&& cfun
->cfg
&& basic_block_info
)
4383 /* Make a CFG based dump. */
4384 check_bb_profile (ENTRY_BLOCK_PTR
, file
);
4385 if (!ignore_topmost_bind
)
4386 fprintf (file
, "{\n");
4388 if (any_var
&& n_basic_blocks
)
4389 fprintf (file
, "\n");
4392 dump_generic_bb (file
, bb
, 2, flags
);
4394 fprintf (file
, "}\n");
4395 check_bb_profile (EXIT_BLOCK_PTR
, file
);
4401 /* Make a tree based dump. */
4402 chain
= DECL_SAVED_TREE (fn
);
4404 if (TREE_CODE (chain
) == BIND_EXPR
)
4406 if (ignore_topmost_bind
)
4408 chain
= BIND_EXPR_BODY (chain
);
4416 if (!ignore_topmost_bind
)
4417 fprintf (file
, "{\n");
4422 fprintf (file
, "\n");
4424 print_generic_stmt_indented (file
, chain
, flags
, indent
);
4425 if (ignore_topmost_bind
)
4426 fprintf (file
, "}\n");
4429 fprintf (file
, "\n\n");
4433 /* Pretty print of the loops intermediate representation. */
4434 static void print_loop (FILE *, struct loop
*, int);
4435 static void print_pred_bbs (FILE *, basic_block bb
);
4436 static void print_succ_bbs (FILE *, basic_block bb
);
4439 /* Print the predecessors indexes of edge E on FILE. */
4442 print_pred_bbs (FILE *file
, basic_block bb
)
4447 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
4448 fprintf (file
, "bb_%d", e
->src
->index
);
4452 /* Print the successors indexes of edge E on FILE. */
4455 print_succ_bbs (FILE *file
, basic_block bb
)
4460 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
4461 fprintf (file
, "bb_%d", e
->src
->index
);
4465 /* Pretty print LOOP on FILE, indented INDENT spaces. */
4468 print_loop (FILE *file
, struct loop
*loop
, int indent
)
4476 s_indent
= (char *) alloca ((size_t) indent
+ 1);
4477 memset ((void *) s_indent
, ' ', (size_t) indent
);
4478 s_indent
[indent
] = '\0';
4480 /* Print the loop's header. */
4481 fprintf (file
, "%sloop_%d\n", s_indent
, loop
->num
);
4483 /* Print the loop's body. */
4484 fprintf (file
, "%s{\n", s_indent
);
4486 if (bb
->loop_father
== loop
)
4488 /* Print the basic_block's header. */
4489 fprintf (file
, "%s bb_%d (preds = {", s_indent
, bb
->index
);
4490 print_pred_bbs (file
, bb
);
4491 fprintf (file
, "}, succs = {");
4492 print_succ_bbs (file
, bb
);
4493 fprintf (file
, "})\n");
4495 /* Print the basic_block's body. */
4496 fprintf (file
, "%s {\n", s_indent
);
4497 tree_dump_bb (bb
, file
, indent
+ 4);
4498 fprintf (file
, "%s }\n", s_indent
);
4501 print_loop (file
, loop
->inner
, indent
+ 2);
4502 fprintf (file
, "%s}\n", s_indent
);
4503 print_loop (file
, loop
->next
, indent
);
4507 /* Follow a CFG edge from the entry point of the program, and on entry
4508 of a loop, pretty print the loop structure on FILE. */
4511 print_loop_ir (FILE *file
)
4515 bb
= BASIC_BLOCK (0);
4516 if (bb
&& bb
->loop_father
)
4517 print_loop (file
, bb
->loop_father
, 0);
4521 /* Debugging loops structure at tree level. */
4524 debug_loop_ir (void)
4526 print_loop_ir (stderr
);
4530 /* Return true if BB ends with a call, possibly followed by some
4531 instructions that must stay with the call. Return false,
4535 tree_block_ends_with_call_p (basic_block bb
)
4537 block_stmt_iterator bsi
= bsi_last (bb
);
4538 return get_call_expr_in (bsi_stmt (bsi
)) != NULL
;
4542 /* Return true if BB ends with a conditional branch. Return false,
4546 tree_block_ends_with_condjump_p (basic_block bb
)
4548 tree stmt
= last_stmt (bb
);
4549 return (stmt
&& TREE_CODE (stmt
) == COND_EXPR
);
4553 /* Return true if we need to add fake edge to exit at statement T.
4554 Helper function for tree_flow_call_edges_add. */
4557 need_fake_edge_p (tree t
)
4561 /* NORETURN and LONGJMP calls already have an edge to exit.
4562 CONST and PURE calls do not need one.
4563 We don't currently check for CONST and PURE here, although
4564 it would be a good idea, because those attributes are
4565 figured out from the RTL in mark_constant_function, and
4566 the counter incrementation code from -fprofile-arcs
4567 leads to different results from -fbranch-probabilities. */
4568 call
= get_call_expr_in (t
);
4570 && !(call_expr_flags (call
) & ECF_NORETURN
))
4573 if (TREE_CODE (t
) == ASM_EXPR
4574 && (ASM_VOLATILE_P (t
) || ASM_INPUT_P (t
)))
4581 /* Add fake edges to the function exit for any non constant and non
4582 noreturn calls, volatile inline assembly in the bitmap of blocks
4583 specified by BLOCKS or to the whole CFG if BLOCKS is zero. Return
4584 the number of blocks that were split.
4586 The goal is to expose cases in which entering a basic block does
4587 not imply that all subsequent instructions must be executed. */
4590 tree_flow_call_edges_add (sbitmap blocks
)
4593 int blocks_split
= 0;
4594 int last_bb
= last_basic_block
;
4595 bool check_last_block
= false;
4597 if (n_basic_blocks
== 0)
4601 check_last_block
= true;
4603 check_last_block
= TEST_BIT (blocks
, EXIT_BLOCK_PTR
->prev_bb
->index
);
4605 /* In the last basic block, before epilogue generation, there will be
4606 a fallthru edge to EXIT. Special care is required if the last insn
4607 of the last basic block is a call because make_edge folds duplicate
4608 edges, which would result in the fallthru edge also being marked
4609 fake, which would result in the fallthru edge being removed by
4610 remove_fake_edges, which would result in an invalid CFG.
4612 Moreover, we can't elide the outgoing fake edge, since the block
4613 profiler needs to take this into account in order to solve the minimal
4614 spanning tree in the case that the call doesn't return.
4616 Handle this by adding a dummy instruction in a new last basic block. */
4617 if (check_last_block
)
4619 basic_block bb
= EXIT_BLOCK_PTR
->prev_bb
;
4620 block_stmt_iterator bsi
= bsi_last (bb
);
4622 if (!bsi_end_p (bsi
))
4625 if (need_fake_edge_p (t
))
4629 e
= find_edge (bb
, EXIT_BLOCK_PTR
);
4632 bsi_insert_on_edge (e
, build_empty_stmt ());
4633 bsi_commit_edge_inserts ();
4638 /* Now add fake edges to the function exit for any non constant
4639 calls since there is no way that we can determine if they will
4641 for (i
= 0; i
< last_bb
; i
++)
4643 basic_block bb
= BASIC_BLOCK (i
);
4644 block_stmt_iterator bsi
;
4645 tree stmt
, last_stmt
;
4650 if (blocks
&& !TEST_BIT (blocks
, i
))
4653 bsi
= bsi_last (bb
);
4654 if (!bsi_end_p (bsi
))
4656 last_stmt
= bsi_stmt (bsi
);
4659 stmt
= bsi_stmt (bsi
);
4660 if (need_fake_edge_p (stmt
))
4663 /* The handling above of the final block before the
4664 epilogue should be enough to verify that there is
4665 no edge to the exit block in CFG already.
4666 Calling make_edge in such case would cause us to
4667 mark that edge as fake and remove it later. */
4668 #ifdef ENABLE_CHECKING
4669 if (stmt
== last_stmt
)
4671 e
= find_edge (bb
, EXIT_BLOCK_PTR
);
4672 gcc_assert (e
== NULL
);
4676 /* Note that the following may create a new basic block
4677 and renumber the existing basic blocks. */
4678 if (stmt
!= last_stmt
)
4680 e
= split_block (bb
, stmt
);
4684 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
4688 while (!bsi_end_p (bsi
));
4693 verify_flow_info ();
4695 return blocks_split
;
4699 tree_purge_dead_eh_edges (basic_block bb
)
4701 bool changed
= false;
4704 tree stmt
= last_stmt (bb
);
4706 if (stmt
&& tree_can_throw_internal (stmt
))
4709 for (ei
= ei_start (bb
->succs
); (e
= ei_safe_edge (ei
)); )
4711 if (e
->flags
& EDGE_EH
)
4720 /* Removal of dead EH edges might change dominators of not
4721 just immediate successors. E.g. when bb1 is changed so that
4722 it no longer can throw and bb1->bb3 and bb1->bb4 are dead
4723 eh edges purged by this function in:
4735 idom(bb5) must be recomputed. For now just free the dominance
4738 free_dominance_info (CDI_DOMINATORS
);
4744 tree_purge_all_dead_eh_edges (bitmap blocks
)
4746 bool changed
= false;
4750 EXECUTE_IF_SET_IN_BITMAP (blocks
, 0, i
, bi
)
4752 changed
|= tree_purge_dead_eh_edges (BASIC_BLOCK (i
));
4758 /* This function is called whenever a new edge is created or
4762 tree_execute_on_growing_pred (edge e
)
4764 basic_block bb
= e
->dest
;
4767 reserve_phi_args_for_new_edge (bb
);
4770 /* This function is called immediately before edge E is removed from
4771 the edge vector E->dest->preds. */
4774 tree_execute_on_shrinking_pred (edge e
)
4776 if (phi_nodes (e
->dest
))
4777 remove_phi_args (e
);
4780 /*---------------------------------------------------------------------------
4781 Helper functions for Loop versioning
4782 ---------------------------------------------------------------------------*/
4784 /* Adjust phi nodes for 'first' basic block. 'second' basic block is a copy
4785 of 'first'. Both of them are dominated by 'new_head' basic block. When
4786 'new_head' was created by 'second's incoming edge it received phi arguments
4787 on the edge by split_edge(). Later, additional edge 'e' was created to
4788 connect 'new_head' and 'first'. Now this routine adds phi args on this
4789 additional edge 'e' that new_head to second edge received as part of edge
4794 tree_lv_adjust_loop_header_phi (basic_block first
, basic_block second
,
4795 basic_block new_head
, edge e
)
4798 edge e2
= find_edge (new_head
, second
);
4800 /* Because NEW_HEAD has been created by splitting SECOND's incoming
4801 edge, we should always have an edge from NEW_HEAD to SECOND. */
4802 gcc_assert (e2
!= NULL
);
4804 /* Browse all 'second' basic block phi nodes and add phi args to
4805 edge 'e' for 'first' head. PHI args are always in correct order. */
4807 for (phi2
= phi_nodes (second
), phi1
= phi_nodes (first
);
4809 phi2
= PHI_CHAIN (phi2
), phi1
= PHI_CHAIN (phi1
))
4811 tree def
= PHI_ARG_DEF (phi2
, e2
->dest_idx
);
4812 add_phi_arg (phi1
, def
, e
);
4816 /* Adds a if else statement to COND_BB with condition COND_EXPR.
4817 SECOND_HEAD is the destination of the THEN and FIRST_HEAD is
4818 the destination of the ELSE part. */
4820 tree_lv_add_condition_to_bb (basic_block first_head
, basic_block second_head
,
4821 basic_block cond_bb
, void *cond_e
)
4823 block_stmt_iterator bsi
;
4824 tree goto1
= NULL_TREE
;
4825 tree goto2
= NULL_TREE
;
4826 tree new_cond_expr
= NULL_TREE
;
4827 tree cond_expr
= (tree
) cond_e
;
4830 /* Build new conditional expr */
4831 goto1
= build1 (GOTO_EXPR
, void_type_node
, tree_block_label (first_head
));
4832 goto2
= build1 (GOTO_EXPR
, void_type_node
, tree_block_label (second_head
));
4833 new_cond_expr
= build3 (COND_EXPR
, void_type_node
, cond_expr
, goto1
, goto2
);
4835 /* Add new cond in cond_bb. */
4836 bsi
= bsi_start (cond_bb
);
4837 bsi_insert_after (&bsi
, new_cond_expr
, BSI_NEW_STMT
);
4838 /* Adjust edges appropriately to connect new head with first head
4839 as well as second head. */
4840 e0
= single_succ_edge (cond_bb
);
4841 e0
->flags
&= ~EDGE_FALLTHRU
;
4842 e0
->flags
|= EDGE_FALSE_VALUE
;
4845 struct cfg_hooks tree_cfg_hooks
= {
4847 tree_verify_flow_info
,
4848 tree_dump_bb
, /* dump_bb */
4849 create_bb
, /* create_basic_block */
4850 tree_redirect_edge_and_branch
,/* redirect_edge_and_branch */
4851 tree_redirect_edge_and_branch_force
,/* redirect_edge_and_branch_force */
4852 remove_bb
, /* delete_basic_block */
4853 tree_split_block
, /* split_block */
4854 tree_move_block_after
, /* move_block_after */
4855 tree_can_merge_blocks_p
, /* can_merge_blocks_p */
4856 tree_merge_blocks
, /* merge_blocks */
4857 tree_predict_edge
, /* predict_edge */
4858 tree_predicted_by_p
, /* predicted_by_p */
4859 tree_can_duplicate_bb_p
, /* can_duplicate_block_p */
4860 tree_duplicate_bb
, /* duplicate_block */
4861 tree_split_edge
, /* split_edge */
4862 tree_make_forwarder_block
, /* make_forward_block */
4863 NULL
, /* tidy_fallthru_edge */
4864 tree_block_ends_with_call_p
, /* block_ends_with_call_p */
4865 tree_block_ends_with_condjump_p
, /* block_ends_with_condjump_p */
4866 tree_flow_call_edges_add
, /* flow_call_edges_add */
4867 tree_execute_on_growing_pred
, /* execute_on_growing_pred */
4868 tree_execute_on_shrinking_pred
, /* execute_on_shrinking_pred */
4869 tree_duplicate_loop_to_header_edge
, /* duplicate loop for trees */
4870 tree_lv_add_condition_to_bb
, /* lv_add_condition_to_bb */
4871 tree_lv_adjust_loop_header_phi
, /* lv_adjust_loop_header_phi*/
4872 extract_true_false_edges_from_block
, /* extract_cond_bb_edges */
4873 flush_pending_stmts
/* flush_pending_stmts */
4877 /* Split all critical edges. */
4880 split_critical_edges (void)
4886 /* split_edge can redirect edges out of SWITCH_EXPRs, which can get
4887 expensive. So we want to enable recording of edge to CASE_LABEL_EXPR
4888 mappings around the calls to split_edge. */
4889 start_recording_case_labels ();
4892 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
4893 if (EDGE_CRITICAL_P (e
) && !(e
->flags
& EDGE_ABNORMAL
))
4898 end_recording_case_labels ();
4901 struct tree_opt_pass pass_split_crit_edges
=
4903 "crited", /* name */
4905 split_critical_edges
, /* execute */
4908 0, /* static_pass_number */
4909 TV_TREE_SPLIT_EDGES
, /* tv_id */
4910 PROP_cfg
, /* properties required */
4911 PROP_no_crit_edges
, /* properties_provided */
4912 0, /* properties_destroyed */
4913 0, /* todo_flags_start */
4914 TODO_dump_func
, /* todo_flags_finish */
4919 /* Return EXP if it is a valid GIMPLE rvalue, else gimplify it into
4920 a temporary, make sure and register it to be renamed if necessary,
4921 and finally return the temporary. Put the statements to compute
4922 EXP before the current statement in BSI. */
4925 gimplify_val (block_stmt_iterator
*bsi
, tree type
, tree exp
)
4927 tree t
, new_stmt
, orig_stmt
;
4929 if (is_gimple_val (exp
))
4932 t
= make_rename_temp (type
, NULL
);
4933 new_stmt
= build (MODIFY_EXPR
, type
, t
, exp
);
4935 orig_stmt
= bsi_stmt (*bsi
);
4936 SET_EXPR_LOCUS (new_stmt
, EXPR_LOCUS (orig_stmt
));
4937 TREE_BLOCK (new_stmt
) = TREE_BLOCK (orig_stmt
);
4939 bsi_insert_before (bsi
, new_stmt
, BSI_SAME_STMT
);
4944 /* Build a ternary operation and gimplify it. Emit code before BSI.
4945 Return the gimple_val holding the result. */
4948 gimplify_build3 (block_stmt_iterator
*bsi
, enum tree_code code
,
4949 tree type
, tree a
, tree b
, tree c
)
4953 ret
= fold (build3 (code
, type
, a
, b
, c
));
4956 return gimplify_val (bsi
, type
, ret
);
4959 /* Build a binary operation and gimplify it. Emit code before BSI.
4960 Return the gimple_val holding the result. */
4963 gimplify_build2 (block_stmt_iterator
*bsi
, enum tree_code code
,
4964 tree type
, tree a
, tree b
)
4968 ret
= fold (build2 (code
, type
, a
, b
));
4971 return gimplify_val (bsi
, type
, ret
);
4974 /* Build a unary operation and gimplify it. Emit code before BSI.
4975 Return the gimple_val holding the result. */
4978 gimplify_build1 (block_stmt_iterator
*bsi
, enum tree_code code
, tree type
,
4983 ret
= fold (build1 (code
, type
, a
));
4986 return gimplify_val (bsi
, type
, ret
);
4991 /* Emit return warnings. */
4994 execute_warn_function_return (void)
4996 #ifdef USE_MAPPED_LOCATION
4997 source_location location
;
5005 /* If we have a path to EXIT, then we do return. */
5006 if (TREE_THIS_VOLATILE (cfun
->decl
)
5007 && EDGE_COUNT (EXIT_BLOCK_PTR
->preds
) > 0)
5009 #ifdef USE_MAPPED_LOCATION
5010 location
= UNKNOWN_LOCATION
;
5014 FOR_EACH_EDGE (e
, ei
, EXIT_BLOCK_PTR
->preds
)
5016 last
= last_stmt (e
->src
);
5017 if (TREE_CODE (last
) == RETURN_EXPR
5018 #ifdef USE_MAPPED_LOCATION
5019 && (location
= EXPR_LOCATION (last
)) != UNKNOWN_LOCATION
)
5021 && (locus
= EXPR_LOCUS (last
)) != NULL
)
5025 #ifdef USE_MAPPED_LOCATION
5026 if (location
== UNKNOWN_LOCATION
)
5027 location
= cfun
->function_end_locus
;
5028 warning (0, "%H%<noreturn%> function does return", &location
);
5031 locus
= &cfun
->function_end_locus
;
5032 warning (0, "%H%<noreturn%> function does return", locus
);
5036 /* If we see "return;" in some basic block, then we do reach the end
5037 without returning a value. */
5038 else if (warn_return_type
5039 && !TREE_NO_WARNING (cfun
->decl
)
5040 && EDGE_COUNT (EXIT_BLOCK_PTR
->preds
) > 0
5041 && !VOID_TYPE_P (TREE_TYPE (TREE_TYPE (cfun
->decl
))))
5043 FOR_EACH_EDGE (e
, ei
, EXIT_BLOCK_PTR
->preds
)
5045 tree last
= last_stmt (e
->src
);
5046 if (TREE_CODE (last
) == RETURN_EXPR
5047 && TREE_OPERAND (last
, 0) == NULL
)
5049 #ifdef USE_MAPPED_LOCATION
5050 location
= EXPR_LOCATION (last
);
5051 if (location
== UNKNOWN_LOCATION
)
5052 location
= cfun
->function_end_locus
;
5053 warning (0, "%Hcontrol reaches end of non-void function", &location
);
5055 locus
= EXPR_LOCUS (last
);
5057 locus
= &cfun
->function_end_locus
;
5058 warning (0, "%Hcontrol reaches end of non-void function", locus
);
5060 TREE_NO_WARNING (cfun
->decl
) = 1;
5068 /* Given a basic block B which ends with a conditional and has
5069 precisely two successors, determine which of the edges is taken if
5070 the conditional is true and which is taken if the conditional is
5071 false. Set TRUE_EDGE and FALSE_EDGE appropriately. */
5074 extract_true_false_edges_from_block (basic_block b
,
5078 edge e
= EDGE_SUCC (b
, 0);
5080 if (e
->flags
& EDGE_TRUE_VALUE
)
5083 *false_edge
= EDGE_SUCC (b
, 1);
5088 *true_edge
= EDGE_SUCC (b
, 1);
5092 struct tree_opt_pass pass_warn_function_return
=
5096 execute_warn_function_return
, /* execute */
5099 0, /* static_pass_number */
5101 PROP_cfg
, /* properties_required */
5102 0, /* properties_provided */
5103 0, /* properties_destroyed */
5104 0, /* todo_flags_start */
5105 0, /* todo_flags_finish */
5109 /* Emit noreturn warnings. */
5112 execute_warn_function_noreturn (void)
5114 if (warn_missing_noreturn
5115 && !TREE_THIS_VOLATILE (cfun
->decl
)
5116 && EDGE_COUNT (EXIT_BLOCK_PTR
->preds
) == 0
5117 && !lang_hooks
.function
.missing_noreturn_ok_p (cfun
->decl
))
5118 warning (0, "%Jfunction might be possible candidate for "
5119 "attribute %<noreturn%>",
5123 struct tree_opt_pass pass_warn_function_noreturn
=
5127 execute_warn_function_noreturn
, /* execute */
5130 0, /* static_pass_number */
5132 PROP_cfg
, /* properties_required */
5133 0, /* properties_provided */
5134 0, /* properties_destroyed */
5135 0, /* todo_flags_start */
5136 0, /* todo_flags_finish */