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"
49 /* This file contains functions for building the Control Flow Graph (CFG)
50 for a function tree. */
52 /* Local declarations. */
54 /* Initial capacity for the basic block array. */
55 static const int initial_cfg_capacity
= 20;
57 /* Mapping of labels to their associated blocks. This can greatly speed up
58 building of the CFG in code with lots of gotos. */
59 static GTY(()) varray_type label_to_block_map
;
61 /* This hash table allows us to efficiently lookup all CASE_LABEL_EXPRs
62 which use a particular edge. The CASE_LABEL_EXPRs are chained together
63 via their TREE_CHAIN field, which we clear after we're done with the
64 hash table to prevent problems with duplication of SWITCH_EXPRs.
66 Access to this list of CASE_LABEL_EXPRs allows us to efficiently
67 update the case vector in response to edge redirections.
69 Right now this table is set up and torn down at key points in the
70 compilation process. It would be nice if we could make the table
71 more persistent. The key is getting notification of changes to
72 the CFG (particularly edge removal, creation and redirection). */
74 struct edge_to_cases_elt
76 /* The edge itself. Necessary for hashing and equality tests. */
79 /* The case labels associated with this edge. We link these up via
80 their TREE_CHAIN field, then we wipe out the TREE_CHAIN fields
81 when we destroy the hash table. This prevents problems when copying
86 static htab_t edge_to_cases
;
91 long num_merged_labels
;
94 static struct cfg_stats_d cfg_stats
;
96 /* Nonzero if we found a computed goto while building basic blocks. */
97 static bool found_computed_goto
;
99 /* Basic blocks and flowgraphs. */
100 static basic_block
create_bb (void *, void *, basic_block
);
101 static void create_block_annotation (basic_block
);
102 static void free_blocks_annotations (void);
103 static void clear_blocks_annotations (void);
104 static void make_blocks (tree
);
105 static void factor_computed_gotos (void);
108 static void make_edges (void);
109 static void make_ctrl_stmt_edges (basic_block
);
110 static void make_exit_edges (basic_block
);
111 static void make_cond_expr_edges (basic_block
);
112 static void make_switch_expr_edges (basic_block
);
113 static void make_goto_expr_edges (basic_block
);
114 static edge
tree_redirect_edge_and_branch (edge
, basic_block
);
115 static edge
tree_try_redirect_by_replacing_jump (edge
, basic_block
);
116 static void split_critical_edges (void);
117 static bool remove_fallthru_edge (VEC(edge
) *);
119 /* Various helpers. */
120 static inline bool stmt_starts_bb_p (tree
, tree
);
121 static int tree_verify_flow_info (void);
122 static void tree_make_forwarder_block (edge
);
123 static bool tree_forwarder_block_p (basic_block
, bool);
124 static void tree_cfg2vcg (FILE *);
126 /* Flowgraph optimization and cleanup. */
127 static void tree_merge_blocks (basic_block
, basic_block
);
128 static bool tree_can_merge_blocks_p (basic_block
, basic_block
);
129 static void remove_bb (basic_block
);
130 static bool cleanup_control_flow (void);
131 static bool cleanup_control_expr_graph (basic_block
, block_stmt_iterator
);
132 static edge
find_taken_edge_computed_goto (basic_block
, tree
);
133 static edge
find_taken_edge_cond_expr (basic_block
, tree
);
134 static edge
find_taken_edge_switch_expr (basic_block
, tree
);
135 static tree
find_case_label_for_value (tree
, tree
);
136 static bool phi_alternatives_equal (basic_block
, edge
, edge
);
137 static bool cleanup_forwarder_blocks (void);
140 /*---------------------------------------------------------------------------
142 ---------------------------------------------------------------------------*/
144 /* Entry point to the CFG builder for trees. TP points to the list of
145 statements to be added to the flowgraph. */
148 build_tree_cfg (tree
*tp
)
150 /* Register specific tree functions. */
151 tree_register_cfg_hooks ();
153 /* Initialize rbi_pool. */
156 /* Initialize the basic block array. */
158 profile_status
= PROFILE_ABSENT
;
160 last_basic_block
= 0;
161 VARRAY_BB_INIT (basic_block_info
, initial_cfg_capacity
, "basic_block_info");
162 memset ((void *) &cfg_stats
, 0, sizeof (cfg_stats
));
164 /* Build a mapping of labels to their associated blocks. */
165 VARRAY_BB_INIT (label_to_block_map
, initial_cfg_capacity
,
166 "label to block map");
168 ENTRY_BLOCK_PTR
->next_bb
= EXIT_BLOCK_PTR
;
169 EXIT_BLOCK_PTR
->prev_bb
= ENTRY_BLOCK_PTR
;
171 found_computed_goto
= 0;
174 /* Computed gotos are hell to deal with, especially if there are
175 lots of them with a large number of destinations. So we factor
176 them to a common computed goto location before we build the
177 edge list. After we convert back to normal form, we will un-factor
178 the computed gotos since factoring introduces an unwanted jump. */
179 if (found_computed_goto
)
180 factor_computed_gotos ();
182 /* Make sure there is always at least one block, even if it's empty. */
183 if (n_basic_blocks
== 0)
184 create_empty_bb (ENTRY_BLOCK_PTR
);
186 create_block_annotation (ENTRY_BLOCK_PTR
);
187 create_block_annotation (EXIT_BLOCK_PTR
);
189 /* Adjust the size of the array. */
190 VARRAY_GROW (basic_block_info
, n_basic_blocks
);
192 /* To speed up statement iterator walks, we first purge dead labels. */
193 cleanup_dead_labels ();
195 /* Group case nodes to reduce the number of edges.
196 We do this after cleaning up dead labels because otherwise we miss
197 a lot of obvious case merging opportunities. */
198 group_case_labels ();
200 /* Create the edges of the flowgraph. */
203 /* Debugging dumps. */
205 /* Write the flowgraph to a VCG file. */
207 int local_dump_flags
;
208 FILE *dump_file
= dump_begin (TDI_vcg
, &local_dump_flags
);
211 tree_cfg2vcg (dump_file
);
212 dump_end (TDI_vcg
, dump_file
);
216 /* Dump a textual representation of the flowgraph. */
218 dump_tree_cfg (dump_file
, dump_flags
);
222 execute_build_cfg (void)
224 build_tree_cfg (&DECL_SAVED_TREE (current_function_decl
));
227 struct tree_opt_pass pass_build_cfg
=
231 execute_build_cfg
, /* execute */
234 0, /* static_pass_number */
235 TV_TREE_CFG
, /* tv_id */
236 PROP_gimple_leh
, /* properties_required */
237 PROP_cfg
, /* properties_provided */
238 0, /* properties_destroyed */
239 0, /* todo_flags_start */
240 TODO_verify_stmts
, /* todo_flags_finish */
244 /* Search the CFG for any computed gotos. If found, factor them to a
245 common computed goto site. Also record the location of that site so
246 that we can un-factor the gotos after we have converted back to
250 factor_computed_gotos (void)
253 tree factored_label_decl
= NULL
;
255 tree factored_computed_goto_label
= NULL
;
256 tree factored_computed_goto
= NULL
;
258 /* We know there are one or more computed gotos in this function.
259 Examine the last statement in each basic block to see if the block
260 ends with a computed goto. */
264 block_stmt_iterator bsi
= bsi_last (bb
);
269 last
= bsi_stmt (bsi
);
271 /* Ignore the computed goto we create when we factor the original
273 if (last
== factored_computed_goto
)
276 /* If the last statement is a computed goto, factor it. */
277 if (computed_goto_p (last
))
281 /* The first time we find a computed goto we need to create
282 the factored goto block and the variable each original
283 computed goto will use for their goto destination. */
284 if (! factored_computed_goto
)
286 basic_block new_bb
= create_empty_bb (bb
);
287 block_stmt_iterator new_bsi
= bsi_start (new_bb
);
289 /* Create the destination of the factored goto. Each original
290 computed goto will put its desired destination into this
291 variable and jump to the label we create immediately
293 var
= create_tmp_var (ptr_type_node
, "gotovar");
295 /* Build a label for the new block which will contain the
296 factored computed goto. */
297 factored_label_decl
= create_artificial_label ();
298 factored_computed_goto_label
299 = build1 (LABEL_EXPR
, void_type_node
, factored_label_decl
);
300 bsi_insert_after (&new_bsi
, factored_computed_goto_label
,
303 /* Build our new computed goto. */
304 factored_computed_goto
= build1 (GOTO_EXPR
, void_type_node
, var
);
305 bsi_insert_after (&new_bsi
, factored_computed_goto
,
309 /* Copy the original computed goto's destination into VAR. */
310 assignment
= build (MODIFY_EXPR
, ptr_type_node
,
311 var
, GOTO_DESTINATION (last
));
312 bsi_insert_before (&bsi
, assignment
, BSI_SAME_STMT
);
314 /* And re-vector the computed goto to the new destination. */
315 GOTO_DESTINATION (last
) = factored_label_decl
;
321 /* Create annotations for a single basic block. */
324 create_block_annotation (basic_block bb
)
326 /* Verify that the tree_annotations field is clear. */
327 gcc_assert (!bb
->tree_annotations
);
328 bb
->tree_annotations
= ggc_alloc_cleared (sizeof (struct bb_ann_d
));
332 /* Free the annotations for all the basic blocks. */
334 static void free_blocks_annotations (void)
336 clear_blocks_annotations ();
340 /* Clear the annotations for all the basic blocks. */
343 clear_blocks_annotations (void)
347 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
, NULL
, next_bb
)
348 bb
->tree_annotations
= NULL
;
352 /* Build a flowgraph for the statement_list STMT_LIST. */
355 make_blocks (tree stmt_list
)
357 tree_stmt_iterator i
= tsi_start (stmt_list
);
359 bool start_new_block
= true;
360 bool first_stmt_of_list
= true;
361 basic_block bb
= ENTRY_BLOCK_PTR
;
363 while (!tsi_end_p (i
))
370 /* If the statement starts a new basic block or if we have determined
371 in a previous pass that we need to create a new block for STMT, do
373 if (start_new_block
|| stmt_starts_bb_p (stmt
, prev_stmt
))
375 if (!first_stmt_of_list
)
376 stmt_list
= tsi_split_statement_list_before (&i
);
377 bb
= create_basic_block (stmt_list
, NULL
, bb
);
378 start_new_block
= false;
381 /* Now add STMT to BB and create the subgraphs for special statement
383 set_bb_for_stmt (stmt
, bb
);
385 if (computed_goto_p (stmt
))
386 found_computed_goto
= true;
388 /* If STMT is a basic block terminator, set START_NEW_BLOCK for the
390 if (stmt_ends_bb_p (stmt
))
391 start_new_block
= true;
394 first_stmt_of_list
= false;
399 /* Create and return a new empty basic block after bb AFTER. */
402 create_bb (void *h
, void *e
, basic_block after
)
408 /* Create and initialize a new basic block. Since alloc_block uses
409 ggc_alloc_cleared to allocate a basic block, we do not have to
410 clear the newly allocated basic block here. */
413 bb
->index
= last_basic_block
;
415 bb
->stmt_list
= h
? h
: alloc_stmt_list ();
417 /* Add the new block to the linked list of blocks. */
418 link_block (bb
, after
);
420 /* Grow the basic block array if needed. */
421 if ((size_t) last_basic_block
== VARRAY_SIZE (basic_block_info
))
423 size_t new_size
= last_basic_block
+ (last_basic_block
+ 3) / 4;
424 VARRAY_GROW (basic_block_info
, new_size
);
427 /* Add the newly created block to the array. */
428 BASIC_BLOCK (last_basic_block
) = bb
;
430 create_block_annotation (bb
);
435 initialize_bb_rbi (bb
);
440 /*---------------------------------------------------------------------------
442 ---------------------------------------------------------------------------*/
444 /* Fold COND_EXPR_COND of each COND_EXPR. */
447 fold_cond_expr_cond (void)
453 tree stmt
= last_stmt (bb
);
456 && TREE_CODE (stmt
) == COND_EXPR
)
458 tree cond
= fold (COND_EXPR_COND (stmt
));
459 if (integer_zerop (cond
))
460 COND_EXPR_COND (stmt
) = boolean_false_node
;
461 else if (integer_onep (cond
))
462 COND_EXPR_COND (stmt
) = boolean_true_node
;
467 /* Join all the blocks in the flowgraph. */
474 /* Create an edge from entry to the first block with executable
476 make_edge (ENTRY_BLOCK_PTR
, BASIC_BLOCK (0), EDGE_FALLTHRU
);
478 /* Traverse the basic block array placing edges. */
481 tree first
= first_stmt (bb
);
482 tree last
= last_stmt (bb
);
486 /* Edges for statements that always alter flow control. */
487 if (is_ctrl_stmt (last
))
488 make_ctrl_stmt_edges (bb
);
490 /* Edges for statements that sometimes alter flow control. */
491 if (is_ctrl_altering_stmt (last
))
492 make_exit_edges (bb
);
495 /* Finally, if no edges were created above, this is a regular
496 basic block that only needs a fallthru edge. */
497 if (EDGE_COUNT (bb
->succs
) == 0)
498 make_edge (bb
, bb
->next_bb
, EDGE_FALLTHRU
);
501 /* We do not care about fake edges, so remove any that the CFG
502 builder inserted for completeness. */
503 remove_fake_exit_edges ();
505 /* Fold COND_EXPR_COND of each COND_EXPR. */
506 fold_cond_expr_cond ();
508 /* Clean up the graph and warn for unreachable code. */
513 /* Create edges for control statement at basic block BB. */
516 make_ctrl_stmt_edges (basic_block bb
)
518 tree last
= last_stmt (bb
);
521 switch (TREE_CODE (last
))
524 make_goto_expr_edges (bb
);
528 make_edge (bb
, EXIT_BLOCK_PTR
, 0);
532 make_cond_expr_edges (bb
);
536 make_switch_expr_edges (bb
);
540 make_eh_edges (last
);
541 /* Yet another NORETURN hack. */
542 if (EDGE_COUNT (bb
->succs
) == 0)
543 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
552 /* Create exit edges for statements in block BB that alter the flow of
553 control. Statements that alter the control flow are 'goto', 'return'
554 and calls to non-returning functions. */
557 make_exit_edges (basic_block bb
)
559 tree last
= last_stmt (bb
), op
;
562 switch (TREE_CODE (last
))
565 /* If this function receives a nonlocal goto, then we need to
566 make edges from this call site to all the nonlocal goto
568 if (TREE_SIDE_EFFECTS (last
)
569 && current_function_has_nonlocal_label
)
570 make_goto_expr_edges (bb
);
572 /* If this statement has reachable exception handlers, then
573 create abnormal edges to them. */
574 make_eh_edges (last
);
576 /* Some calls are known not to return. For such calls we create
579 We really need to revamp how we build edges so that it's not
580 such a bloody pain to avoid creating edges for this case since
581 all we do is remove these edges when we're done building the
583 if (call_expr_flags (last
) & ECF_NORETURN
)
585 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
589 /* Don't forget the fall-thru edge. */
590 make_edge (bb
, bb
->next_bb
, EDGE_FALLTHRU
);
594 /* A MODIFY_EXPR may have a CALL_EXPR on its RHS and the CALL_EXPR
595 may have an abnormal edge. Search the RHS for this case and
596 create any required edges. */
597 op
= get_call_expr_in (last
);
598 if (op
&& TREE_SIDE_EFFECTS (op
)
599 && current_function_has_nonlocal_label
)
600 make_goto_expr_edges (bb
);
602 make_eh_edges (last
);
603 make_edge (bb
, bb
->next_bb
, EDGE_FALLTHRU
);
612 /* Create the edges for a COND_EXPR starting at block BB.
613 At this point, both clauses must contain only simple gotos. */
616 make_cond_expr_edges (basic_block bb
)
618 tree entry
= last_stmt (bb
);
619 basic_block then_bb
, else_bb
;
620 tree then_label
, else_label
;
623 gcc_assert (TREE_CODE (entry
) == COND_EXPR
);
625 /* Entry basic blocks for each component. */
626 then_label
= GOTO_DESTINATION (COND_EXPR_THEN (entry
));
627 else_label
= GOTO_DESTINATION (COND_EXPR_ELSE (entry
));
628 then_bb
= label_to_block (then_label
);
629 else_bb
= label_to_block (else_label
);
631 make_edge (bb
, then_bb
, EDGE_TRUE_VALUE
);
632 make_edge (bb
, else_bb
, EDGE_FALSE_VALUE
);
635 /* Hashing routine for EDGE_TO_CASES. */
638 edge_to_cases_hash (const void *p
)
640 edge e
= ((struct edge_to_cases_elt
*)p
)->e
;
642 /* Hash on the edge itself (which is a pointer). */
643 return htab_hash_pointer (e
);
646 /* Equality routine for EDGE_TO_CASES, edges are unique, so testing
647 for equality is just a pointer comparison. */
650 edge_to_cases_eq (const void *p1
, const void *p2
)
652 edge e1
= ((struct edge_to_cases_elt
*)p1
)->e
;
653 edge e2
= ((struct edge_to_cases_elt
*)p2
)->e
;
658 /* Called for each element in the hash table (P) as we delete the
659 edge to cases hash table.
661 Clear all the TREE_CHAINs to prevent problems with copying of
662 SWITCH_EXPRs and structure sharing rules, then free the hash table
666 edge_to_cases_cleanup (void *p
)
668 struct edge_to_cases_elt
*elt
= p
;
671 for (t
= elt
->case_labels
; t
; t
= next
)
673 next
= TREE_CHAIN (t
);
674 TREE_CHAIN (t
) = NULL
;
679 /* Start recording information mapping edges to case labels. */
682 start_recording_case_labels (void)
684 gcc_assert (edge_to_cases
== NULL
);
686 edge_to_cases
= htab_create (37,
689 edge_to_cases_cleanup
);
692 /* Return nonzero if we are recording information for case labels. */
695 recording_case_labels_p (void)
697 return (edge_to_cases
!= NULL
);
700 /* Stop recording information mapping edges to case labels and
701 remove any information we have recorded. */
703 end_recording_case_labels (void)
705 htab_delete (edge_to_cases
);
706 edge_to_cases
= NULL
;
709 /* Record that CASE_LABEL (a CASE_LABEL_EXPR) references edge E. */
712 record_switch_edge (edge e
, tree case_label
)
714 struct edge_to_cases_elt
*elt
;
717 /* Build a hash table element so we can see if E is already
719 elt
= xmalloc (sizeof (struct edge_to_cases_elt
));
721 elt
->case_labels
= case_label
;
723 slot
= htab_find_slot (edge_to_cases
, elt
, INSERT
);
727 /* E was not in the hash table. Install E into the hash table. */
732 /* E was already in the hash table. Free ELT as we do not need it
736 /* Get the entry stored in the hash table. */
737 elt
= (struct edge_to_cases_elt
*) *slot
;
739 /* Add it to the chain of CASE_LABEL_EXPRs referencing E. */
740 TREE_CHAIN (case_label
) = elt
->case_labels
;
741 elt
->case_labels
= case_label
;
745 /* If we are inside a {start,end}_recording_cases block, then return
746 a chain of CASE_LABEL_EXPRs from T which reference E.
748 Otherwise return NULL. */
751 get_cases_for_edge (edge e
, tree t
)
753 struct edge_to_cases_elt elt
, *elt_p
;
758 /* If we are not recording cases, then we do not have CASE_LABEL_EXPR
759 chains available. Return NULL so the caller can detect this case. */
760 if (!recording_case_labels_p ())
765 elt
.case_labels
= NULL
;
766 slot
= htab_find_slot (edge_to_cases
, &elt
, NO_INSERT
);
770 elt_p
= (struct edge_to_cases_elt
*)*slot
;
771 return elt_p
->case_labels
;
774 /* If we did not find E in the hash table, then this must be the first
775 time we have been queried for information about E & T. Add all the
776 elements from T to the hash table then perform the query again. */
778 vec
= SWITCH_LABELS (t
);
779 n
= TREE_VEC_LENGTH (vec
);
780 for (i
= 0; i
< n
; i
++)
782 tree lab
= CASE_LABEL (TREE_VEC_ELT (vec
, i
));
783 basic_block label_bb
= label_to_block (lab
);
784 record_switch_edge (find_edge (e
->src
, label_bb
), TREE_VEC_ELT (vec
, i
));
789 /* Create the edges for a SWITCH_EXPR starting at block BB.
790 At this point, the switch body has been lowered and the
791 SWITCH_LABELS filled in, so this is in effect a multi-way branch. */
794 make_switch_expr_edges (basic_block bb
)
796 tree entry
= last_stmt (bb
);
800 vec
= SWITCH_LABELS (entry
);
801 n
= TREE_VEC_LENGTH (vec
);
803 for (i
= 0; i
< n
; ++i
)
805 tree lab
= CASE_LABEL (TREE_VEC_ELT (vec
, i
));
806 basic_block label_bb
= label_to_block (lab
);
807 make_edge (bb
, label_bb
, 0);
812 /* Return the basic block holding label DEST. */
815 label_to_block (tree dest
)
817 int uid
= LABEL_DECL_UID (dest
);
819 /* We would die hard when faced by an undefined label. Emit a label to
820 the very first basic block. This will hopefully make even the dataflow
821 and undefined variable warnings quite right. */
822 if ((errorcount
|| sorrycount
) && uid
< 0)
824 block_stmt_iterator bsi
= bsi_start (BASIC_BLOCK (0));
827 stmt
= build1 (LABEL_EXPR
, void_type_node
, dest
);
828 bsi_insert_before (&bsi
, stmt
, BSI_NEW_STMT
);
829 uid
= LABEL_DECL_UID (dest
);
831 return VARRAY_BB (label_to_block_map
, uid
);
835 /* Create edges for a goto statement at block BB. */
838 make_goto_expr_edges (basic_block bb
)
841 basic_block target_bb
;
843 block_stmt_iterator last
= bsi_last (bb
);
845 goto_t
= bsi_stmt (last
);
847 /* If the last statement is not a GOTO (i.e., it is a RETURN_EXPR,
848 CALL_EXPR or MODIFY_EXPR), then the edge is an abnormal edge resulting
849 from a nonlocal goto. */
850 if (TREE_CODE (goto_t
) != GOTO_EXPR
)
854 tree dest
= GOTO_DESTINATION (goto_t
);
857 /* A GOTO to a local label creates normal edges. */
858 if (simple_goto_p (goto_t
))
860 edge e
= make_edge (bb
, label_to_block (dest
), EDGE_FALLTHRU
);
861 #ifdef USE_MAPPED_LOCATION
862 e
->goto_locus
= EXPR_LOCATION (goto_t
);
864 e
->goto_locus
= EXPR_LOCUS (goto_t
);
870 /* Nothing more to do for nonlocal gotos. */
871 if (TREE_CODE (dest
) == LABEL_DECL
)
874 /* Computed gotos remain. */
877 /* Look for the block starting with the destination label. In the
878 case of a computed goto, make an edge to any label block we find
880 FOR_EACH_BB (target_bb
)
882 block_stmt_iterator bsi
;
884 for (bsi
= bsi_start (target_bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
886 tree target
= bsi_stmt (bsi
);
888 if (TREE_CODE (target
) != LABEL_EXPR
)
892 /* Computed GOTOs. Make an edge to every label block that has
893 been marked as a potential target for a computed goto. */
894 (FORCED_LABEL (LABEL_EXPR_LABEL (target
)) && for_call
== 0)
895 /* Nonlocal GOTO target. Make an edge to every label block
896 that has been marked as a potential target for a nonlocal
898 || (DECL_NONLOCAL (LABEL_EXPR_LABEL (target
)) && for_call
== 1))
900 make_edge (bb
, target_bb
, EDGE_ABNORMAL
);
906 /* Degenerate case of computed goto with no labels. */
907 if (!for_call
&& EDGE_COUNT (bb
->succs
) == 0)
908 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
912 /*---------------------------------------------------------------------------
914 ---------------------------------------------------------------------------*/
916 /* Remove unreachable blocks and other miscellaneous clean up work. */
919 cleanup_tree_cfg (void)
923 timevar_push (TV_TREE_CLEANUP_CFG
);
925 retval
= cleanup_control_flow ();
926 retval
|= delete_unreachable_blocks ();
928 /* cleanup_forwarder_blocks can redirect edges out of SWITCH_EXPRs,
929 which can get expensive. So we want to enable recording of edge
930 to CASE_LABEL_EXPR mappings around the call to
931 cleanup_forwarder_blocks. */
932 start_recording_case_labels ();
933 retval
|= cleanup_forwarder_blocks ();
934 end_recording_case_labels ();
936 #ifdef ENABLE_CHECKING
939 gcc_assert (!cleanup_control_flow ());
940 gcc_assert (!delete_unreachable_blocks ());
941 gcc_assert (!cleanup_forwarder_blocks ());
945 /* Merging the blocks creates no new opportunities for the other
946 optimizations, so do it here. */
947 retval
|= merge_seq_blocks ();
951 #ifdef ENABLE_CHECKING
954 timevar_pop (TV_TREE_CLEANUP_CFG
);
959 /* Cleanup cfg and repair loop structures. */
962 cleanup_tree_cfg_loop (void)
964 bitmap changed_bbs
= BITMAP_ALLOC (NULL
);
968 fix_loop_structure (current_loops
, changed_bbs
);
969 calculate_dominance_info (CDI_DOMINATORS
);
971 /* This usually does nothing. But sometimes parts of cfg that originally
972 were inside a loop get out of it due to edge removal (since they
973 become unreachable by back edges from latch). */
974 rewrite_into_loop_closed_ssa (changed_bbs
);
976 BITMAP_FREE (changed_bbs
);
978 #ifdef ENABLE_CHECKING
979 verify_loop_structure (current_loops
);
983 /* Cleanup useless labels in basic blocks. This is something we wish
984 to do early because it allows us to group case labels before creating
985 the edges for the CFG, and it speeds up block statement iterators in
987 We only run this pass once, running it more than once is probably not
990 /* A map from basic block index to the leading label of that block. */
991 static tree
*label_for_bb
;
993 /* Callback for for_each_eh_region. Helper for cleanup_dead_labels. */
995 update_eh_label (struct eh_region
*region
)
997 tree old_label
= get_eh_region_tree_label (region
);
1001 basic_block bb
= label_to_block (old_label
);
1003 /* ??? After optimizing, there may be EH regions with labels
1004 that have already been removed from the function body, so
1005 there is no basic block for them. */
1009 new_label
= label_for_bb
[bb
->index
];
1010 set_eh_region_tree_label (region
, new_label
);
1014 /* Given LABEL return the first label in the same basic block. */
1016 main_block_label (tree label
)
1018 basic_block bb
= label_to_block (label
);
1020 /* label_to_block possibly inserted undefined label into the chain. */
1021 if (!label_for_bb
[bb
->index
])
1022 label_for_bb
[bb
->index
] = label
;
1023 return label_for_bb
[bb
->index
];
1026 /* Cleanup redundant labels. This is a three-step process:
1027 1) Find the leading label for each block.
1028 2) Redirect all references to labels to the leading labels.
1029 3) Cleanup all useless labels. */
1032 cleanup_dead_labels (void)
1035 label_for_bb
= xcalloc (last_basic_block
, sizeof (tree
));
1037 /* Find a suitable label for each block. We use the first user-defined
1038 label if there is one, or otherwise just the first label we see. */
1041 block_stmt_iterator i
;
1043 for (i
= bsi_start (bb
); !bsi_end_p (i
); bsi_next (&i
))
1045 tree label
, stmt
= bsi_stmt (i
);
1047 if (TREE_CODE (stmt
) != LABEL_EXPR
)
1050 label
= LABEL_EXPR_LABEL (stmt
);
1052 /* If we have not yet seen a label for the current block,
1053 remember this one and see if there are more labels. */
1054 if (! label_for_bb
[bb
->index
])
1056 label_for_bb
[bb
->index
] = label
;
1060 /* If we did see a label for the current block already, but it
1061 is an artificially created label, replace it if the current
1062 label is a user defined label. */
1063 if (! DECL_ARTIFICIAL (label
)
1064 && DECL_ARTIFICIAL (label_for_bb
[bb
->index
]))
1066 label_for_bb
[bb
->index
] = label
;
1072 /* Now redirect all jumps/branches to the selected label.
1073 First do so for each block ending in a control statement. */
1076 tree stmt
= last_stmt (bb
);
1080 switch (TREE_CODE (stmt
))
1084 tree true_branch
, false_branch
;
1086 true_branch
= COND_EXPR_THEN (stmt
);
1087 false_branch
= COND_EXPR_ELSE (stmt
);
1089 GOTO_DESTINATION (true_branch
)
1090 = main_block_label (GOTO_DESTINATION (true_branch
));
1091 GOTO_DESTINATION (false_branch
)
1092 = main_block_label (GOTO_DESTINATION (false_branch
));
1100 tree vec
= SWITCH_LABELS (stmt
);
1101 size_t n
= TREE_VEC_LENGTH (vec
);
1103 /* Replace all destination labels. */
1104 for (i
= 0; i
< n
; ++i
)
1106 tree elt
= TREE_VEC_ELT (vec
, i
);
1107 tree label
= main_block_label (CASE_LABEL (elt
));
1108 CASE_LABEL (elt
) = label
;
1113 /* We have to handle GOTO_EXPRs until they're removed, and we don't
1114 remove them until after we've created the CFG edges. */
1116 if (! computed_goto_p (stmt
))
1118 GOTO_DESTINATION (stmt
)
1119 = main_block_label (GOTO_DESTINATION (stmt
));
1128 for_each_eh_region (update_eh_label
);
1130 /* Finally, purge dead labels. All user-defined labels and labels that
1131 can be the target of non-local gotos are preserved. */
1134 block_stmt_iterator i
;
1135 tree label_for_this_bb
= label_for_bb
[bb
->index
];
1137 if (! label_for_this_bb
)
1140 for (i
= bsi_start (bb
); !bsi_end_p (i
); )
1142 tree label
, stmt
= bsi_stmt (i
);
1144 if (TREE_CODE (stmt
) != LABEL_EXPR
)
1147 label
= LABEL_EXPR_LABEL (stmt
);
1149 if (label
== label_for_this_bb
1150 || ! DECL_ARTIFICIAL (label
)
1151 || DECL_NONLOCAL (label
))
1158 free (label_for_bb
);
1161 /* Look for blocks ending in a multiway branch (a SWITCH_EXPR in GIMPLE),
1162 and scan the sorted vector of cases. Combine the ones jumping to the
1164 Eg. three separate entries 1: 2: 3: become one entry 1..3: */
1167 group_case_labels (void)
1173 tree stmt
= last_stmt (bb
);
1174 if (stmt
&& TREE_CODE (stmt
) == SWITCH_EXPR
)
1176 tree labels
= SWITCH_LABELS (stmt
);
1177 int old_size
= TREE_VEC_LENGTH (labels
);
1178 int i
, j
, new_size
= old_size
;
1179 tree default_case
= TREE_VEC_ELT (labels
, old_size
- 1);
1182 /* The default label is always the last case in a switch
1183 statement after gimplification. */
1184 default_label
= CASE_LABEL (default_case
);
1186 /* Look for possible opportunities to merge cases.
1187 Ignore the last element of the label vector because it
1188 must be the default case. */
1190 while (i
< old_size
- 1)
1192 tree base_case
, base_label
, base_high
;
1193 base_case
= TREE_VEC_ELT (labels
, i
);
1195 gcc_assert (base_case
);
1196 base_label
= CASE_LABEL (base_case
);
1198 /* Discard cases that have the same destination as the
1200 if (base_label
== default_label
)
1202 TREE_VEC_ELT (labels
, i
) = NULL_TREE
;
1208 base_high
= CASE_HIGH (base_case
) ?
1209 CASE_HIGH (base_case
) : CASE_LOW (base_case
);
1211 /* Try to merge case labels. Break out when we reach the end
1212 of the label vector or when we cannot merge the next case
1213 label with the current one. */
1214 while (i
< old_size
- 1)
1216 tree merge_case
= TREE_VEC_ELT (labels
, i
);
1217 tree merge_label
= CASE_LABEL (merge_case
);
1218 tree t
= int_const_binop (PLUS_EXPR
, base_high
,
1219 integer_one_node
, 1);
1221 /* Merge the cases if they jump to the same place,
1222 and their ranges are consecutive. */
1223 if (merge_label
== base_label
1224 && tree_int_cst_equal (CASE_LOW (merge_case
), t
))
1226 base_high
= CASE_HIGH (merge_case
) ?
1227 CASE_HIGH (merge_case
) : CASE_LOW (merge_case
);
1228 CASE_HIGH (base_case
) = base_high
;
1229 TREE_VEC_ELT (labels
, i
) = NULL_TREE
;
1238 /* Compress the case labels in the label vector, and adjust the
1239 length of the vector. */
1240 for (i
= 0, j
= 0; i
< new_size
; i
++)
1242 while (! TREE_VEC_ELT (labels
, j
))
1244 TREE_VEC_ELT (labels
, i
) = TREE_VEC_ELT (labels
, j
++);
1246 TREE_VEC_LENGTH (labels
) = new_size
;
1251 /* Checks whether we can merge block B into block A. */
1254 tree_can_merge_blocks_p (basic_block a
, basic_block b
)
1257 block_stmt_iterator bsi
;
1259 if (!single_succ_p (a
))
1262 if (single_succ_edge (a
)->flags
& EDGE_ABNORMAL
)
1265 if (single_succ (a
) != b
)
1268 if (!single_pred_p (b
))
1271 if (b
== EXIT_BLOCK_PTR
)
1274 /* If A ends by a statement causing exceptions or something similar, we
1275 cannot merge the blocks. */
1276 stmt
= last_stmt (a
);
1277 if (stmt
&& stmt_ends_bb_p (stmt
))
1280 /* Do not allow a block with only a non-local label to be merged. */
1281 if (stmt
&& TREE_CODE (stmt
) == LABEL_EXPR
1282 && DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt
)))
1285 /* There may be no phi nodes at the start of b. Most of these degenerate
1286 phi nodes should be cleaned up by kill_redundant_phi_nodes. */
1290 /* Do not remove user labels. */
1291 for (bsi
= bsi_start (b
); !bsi_end_p (bsi
); bsi_next (&bsi
))
1293 stmt
= bsi_stmt (bsi
);
1294 if (TREE_CODE (stmt
) != LABEL_EXPR
)
1296 if (!DECL_ARTIFICIAL (LABEL_EXPR_LABEL (stmt
)))
1300 /* Protect the loop latches. */
1302 && b
->loop_father
->latch
== b
)
1309 /* Merge block B into block A. */
1312 tree_merge_blocks (basic_block a
, basic_block b
)
1314 block_stmt_iterator bsi
;
1315 tree_stmt_iterator last
;
1318 fprintf (dump_file
, "Merging blocks %d and %d\n", a
->index
, b
->index
);
1320 /* Ensure that B follows A. */
1321 move_block_after (b
, a
);
1323 gcc_assert (single_succ_edge (a
)->flags
& EDGE_FALLTHRU
);
1324 gcc_assert (!last_stmt (a
) || !stmt_ends_bb_p (last_stmt (a
)));
1326 /* Remove labels from B and set bb_for_stmt to A for other statements. */
1327 for (bsi
= bsi_start (b
); !bsi_end_p (bsi
);)
1329 if (TREE_CODE (bsi_stmt (bsi
)) == LABEL_EXPR
)
1331 tree label
= bsi_stmt (bsi
);
1334 /* Now that we can thread computed gotos, we might have
1335 a situation where we have a forced label in block B
1336 However, the label at the start of block B might still be
1337 used in other ways (think about the runtime checking for
1338 Fortran assigned gotos). So we can not just delete the
1339 label. Instead we move the label to the start of block A. */
1340 if (FORCED_LABEL (LABEL_EXPR_LABEL (label
)))
1342 block_stmt_iterator dest_bsi
= bsi_start (a
);
1343 bsi_insert_before (&dest_bsi
, label
, BSI_NEW_STMT
);
1348 set_bb_for_stmt (bsi_stmt (bsi
), a
);
1353 /* Merge the chains. */
1354 last
= tsi_last (a
->stmt_list
);
1355 tsi_link_after (&last
, b
->stmt_list
, TSI_NEW_STMT
);
1356 b
->stmt_list
= NULL
;
1360 /* Walk the function tree removing unnecessary statements.
1362 * Empty statement nodes are removed
1364 * Unnecessary TRY_FINALLY and TRY_CATCH blocks are removed
1366 * Unnecessary COND_EXPRs are removed
1368 * Some unnecessary BIND_EXPRs are removed
1370 Clearly more work could be done. The trick is doing the analysis
1371 and removal fast enough to be a net improvement in compile times.
1373 Note that when we remove a control structure such as a COND_EXPR
1374 BIND_EXPR, or TRY block, we will need to repeat this optimization pass
1375 to ensure we eliminate all the useless code. */
1386 static void remove_useless_stmts_1 (tree
*, struct rus_data
*);
1389 remove_useless_stmts_warn_notreached (tree stmt
)
1391 if (EXPR_HAS_LOCATION (stmt
))
1393 location_t loc
= EXPR_LOCATION (stmt
);
1394 if (LOCATION_LINE (loc
) > 0)
1396 warning ("%Hwill never be executed", &loc
);
1401 switch (TREE_CODE (stmt
))
1403 case STATEMENT_LIST
:
1405 tree_stmt_iterator i
;
1406 for (i
= tsi_start (stmt
); !tsi_end_p (i
); tsi_next (&i
))
1407 if (remove_useless_stmts_warn_notreached (tsi_stmt (i
)))
1413 if (remove_useless_stmts_warn_notreached (COND_EXPR_COND (stmt
)))
1415 if (remove_useless_stmts_warn_notreached (COND_EXPR_THEN (stmt
)))
1417 if (remove_useless_stmts_warn_notreached (COND_EXPR_ELSE (stmt
)))
1421 case TRY_FINALLY_EXPR
:
1422 case TRY_CATCH_EXPR
:
1423 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt
, 0)))
1425 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt
, 1)))
1430 return remove_useless_stmts_warn_notreached (CATCH_BODY (stmt
));
1431 case EH_FILTER_EXPR
:
1432 return remove_useless_stmts_warn_notreached (EH_FILTER_FAILURE (stmt
));
1434 return remove_useless_stmts_warn_notreached (BIND_EXPR_BLOCK (stmt
));
1437 /* Not a live container. */
1445 remove_useless_stmts_cond (tree
*stmt_p
, struct rus_data
*data
)
1447 tree then_clause
, else_clause
, cond
;
1448 bool save_has_label
, then_has_label
, else_has_label
;
1450 save_has_label
= data
->has_label
;
1451 data
->has_label
= false;
1452 data
->last_goto
= NULL
;
1454 remove_useless_stmts_1 (&COND_EXPR_THEN (*stmt_p
), data
);
1456 then_has_label
= data
->has_label
;
1457 data
->has_label
= false;
1458 data
->last_goto
= NULL
;
1460 remove_useless_stmts_1 (&COND_EXPR_ELSE (*stmt_p
), data
);
1462 else_has_label
= data
->has_label
;
1463 data
->has_label
= save_has_label
| then_has_label
| else_has_label
;
1465 then_clause
= COND_EXPR_THEN (*stmt_p
);
1466 else_clause
= COND_EXPR_ELSE (*stmt_p
);
1467 cond
= fold (COND_EXPR_COND (*stmt_p
));
1469 /* If neither arm does anything at all, we can remove the whole IF. */
1470 if (!TREE_SIDE_EFFECTS (then_clause
) && !TREE_SIDE_EFFECTS (else_clause
))
1472 *stmt_p
= build_empty_stmt ();
1473 data
->repeat
= true;
1476 /* If there are no reachable statements in an arm, then we can
1477 zap the entire conditional. */
1478 else if (integer_nonzerop (cond
) && !else_has_label
)
1480 if (warn_notreached
)
1481 remove_useless_stmts_warn_notreached (else_clause
);
1482 *stmt_p
= then_clause
;
1483 data
->repeat
= true;
1485 else if (integer_zerop (cond
) && !then_has_label
)
1487 if (warn_notreached
)
1488 remove_useless_stmts_warn_notreached (then_clause
);
1489 *stmt_p
= else_clause
;
1490 data
->repeat
= true;
1493 /* Check a couple of simple things on then/else with single stmts. */
1496 tree then_stmt
= expr_only (then_clause
);
1497 tree else_stmt
= expr_only (else_clause
);
1499 /* Notice branches to a common destination. */
1500 if (then_stmt
&& else_stmt
1501 && TREE_CODE (then_stmt
) == GOTO_EXPR
1502 && TREE_CODE (else_stmt
) == GOTO_EXPR
1503 && (GOTO_DESTINATION (then_stmt
) == GOTO_DESTINATION (else_stmt
)))
1505 *stmt_p
= then_stmt
;
1506 data
->repeat
= true;
1509 /* If the THEN/ELSE clause merely assigns a value to a variable or
1510 parameter which is already known to contain that value, then
1511 remove the useless THEN/ELSE clause. */
1512 else if (TREE_CODE (cond
) == VAR_DECL
|| TREE_CODE (cond
) == PARM_DECL
)
1515 && TREE_CODE (else_stmt
) == MODIFY_EXPR
1516 && TREE_OPERAND (else_stmt
, 0) == cond
1517 && integer_zerop (TREE_OPERAND (else_stmt
, 1)))
1518 COND_EXPR_ELSE (*stmt_p
) = alloc_stmt_list ();
1520 else if ((TREE_CODE (cond
) == EQ_EXPR
|| TREE_CODE (cond
) == NE_EXPR
)
1521 && (TREE_CODE (TREE_OPERAND (cond
, 0)) == VAR_DECL
1522 || TREE_CODE (TREE_OPERAND (cond
, 0)) == PARM_DECL
)
1523 && TREE_CONSTANT (TREE_OPERAND (cond
, 1)))
1525 tree stmt
= (TREE_CODE (cond
) == EQ_EXPR
1526 ? then_stmt
: else_stmt
);
1527 tree
*location
= (TREE_CODE (cond
) == EQ_EXPR
1528 ? &COND_EXPR_THEN (*stmt_p
)
1529 : &COND_EXPR_ELSE (*stmt_p
));
1532 && TREE_CODE (stmt
) == MODIFY_EXPR
1533 && TREE_OPERAND (stmt
, 0) == TREE_OPERAND (cond
, 0)
1534 && TREE_OPERAND (stmt
, 1) == TREE_OPERAND (cond
, 1))
1535 *location
= alloc_stmt_list ();
1539 /* Protect GOTOs in the arm of COND_EXPRs from being removed. They
1540 would be re-introduced during lowering. */
1541 data
->last_goto
= NULL
;
1546 remove_useless_stmts_tf (tree
*stmt_p
, struct rus_data
*data
)
1548 bool save_may_branch
, save_may_throw
;
1549 bool this_may_branch
, this_may_throw
;
1551 /* Collect may_branch and may_throw information for the body only. */
1552 save_may_branch
= data
->may_branch
;
1553 save_may_throw
= data
->may_throw
;
1554 data
->may_branch
= false;
1555 data
->may_throw
= false;
1556 data
->last_goto
= NULL
;
1558 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p
, 0), data
);
1560 this_may_branch
= data
->may_branch
;
1561 this_may_throw
= data
->may_throw
;
1562 data
->may_branch
|= save_may_branch
;
1563 data
->may_throw
|= save_may_throw
;
1564 data
->last_goto
= NULL
;
1566 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p
, 1), data
);
1568 /* If the body is empty, then we can emit the FINALLY block without
1569 the enclosing TRY_FINALLY_EXPR. */
1570 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p
, 0)))
1572 *stmt_p
= TREE_OPERAND (*stmt_p
, 1);
1573 data
->repeat
= true;
1576 /* If the handler is empty, then we can emit the TRY block without
1577 the enclosing TRY_FINALLY_EXPR. */
1578 else if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p
, 1)))
1580 *stmt_p
= TREE_OPERAND (*stmt_p
, 0);
1581 data
->repeat
= true;
1584 /* If the body neither throws, nor branches, then we can safely
1585 string the TRY and FINALLY blocks together. */
1586 else if (!this_may_branch
&& !this_may_throw
)
1588 tree stmt
= *stmt_p
;
1589 *stmt_p
= TREE_OPERAND (stmt
, 0);
1590 append_to_statement_list (TREE_OPERAND (stmt
, 1), stmt_p
);
1591 data
->repeat
= true;
1597 remove_useless_stmts_tc (tree
*stmt_p
, struct rus_data
*data
)
1599 bool save_may_throw
, this_may_throw
;
1600 tree_stmt_iterator i
;
1603 /* Collect may_throw information for the body only. */
1604 save_may_throw
= data
->may_throw
;
1605 data
->may_throw
= false;
1606 data
->last_goto
= NULL
;
1608 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p
, 0), data
);
1610 this_may_throw
= data
->may_throw
;
1611 data
->may_throw
= save_may_throw
;
1613 /* If the body cannot throw, then we can drop the entire TRY_CATCH_EXPR. */
1614 if (!this_may_throw
)
1616 if (warn_notreached
)
1617 remove_useless_stmts_warn_notreached (TREE_OPERAND (*stmt_p
, 1));
1618 *stmt_p
= TREE_OPERAND (*stmt_p
, 0);
1619 data
->repeat
= true;
1623 /* Process the catch clause specially. We may be able to tell that
1624 no exceptions propagate past this point. */
1626 this_may_throw
= true;
1627 i
= tsi_start (TREE_OPERAND (*stmt_p
, 1));
1628 stmt
= tsi_stmt (i
);
1629 data
->last_goto
= NULL
;
1631 switch (TREE_CODE (stmt
))
1634 for (; !tsi_end_p (i
); tsi_next (&i
))
1636 stmt
= tsi_stmt (i
);
1637 /* If we catch all exceptions, then the body does not
1638 propagate exceptions past this point. */
1639 if (CATCH_TYPES (stmt
) == NULL
)
1640 this_may_throw
= false;
1641 data
->last_goto
= NULL
;
1642 remove_useless_stmts_1 (&CATCH_BODY (stmt
), data
);
1646 case EH_FILTER_EXPR
:
1647 if (EH_FILTER_MUST_NOT_THROW (stmt
))
1648 this_may_throw
= false;
1649 else if (EH_FILTER_TYPES (stmt
) == NULL
)
1650 this_may_throw
= false;
1651 remove_useless_stmts_1 (&EH_FILTER_FAILURE (stmt
), data
);
1655 /* Otherwise this is a cleanup. */
1656 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p
, 1), data
);
1658 /* If the cleanup is empty, then we can emit the TRY block without
1659 the enclosing TRY_CATCH_EXPR. */
1660 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p
, 1)))
1662 *stmt_p
= TREE_OPERAND (*stmt_p
, 0);
1663 data
->repeat
= true;
1667 data
->may_throw
|= this_may_throw
;
1672 remove_useless_stmts_bind (tree
*stmt_p
, struct rus_data
*data
)
1676 /* First remove anything underneath the BIND_EXPR. */
1677 remove_useless_stmts_1 (&BIND_EXPR_BODY (*stmt_p
), data
);
1679 /* If the BIND_EXPR has no variables, then we can pull everything
1680 up one level and remove the BIND_EXPR, unless this is the toplevel
1681 BIND_EXPR for the current function or an inlined function.
1683 When this situation occurs we will want to apply this
1684 optimization again. */
1685 block
= BIND_EXPR_BLOCK (*stmt_p
);
1686 if (BIND_EXPR_VARS (*stmt_p
) == NULL_TREE
1687 && *stmt_p
!= DECL_SAVED_TREE (current_function_decl
)
1689 || ! BLOCK_ABSTRACT_ORIGIN (block
)
1690 || (TREE_CODE (BLOCK_ABSTRACT_ORIGIN (block
))
1693 *stmt_p
= BIND_EXPR_BODY (*stmt_p
);
1694 data
->repeat
= true;
1700 remove_useless_stmts_goto (tree
*stmt_p
, struct rus_data
*data
)
1702 tree dest
= GOTO_DESTINATION (*stmt_p
);
1704 data
->may_branch
= true;
1705 data
->last_goto
= NULL
;
1707 /* Record the last goto expr, so that we can delete it if unnecessary. */
1708 if (TREE_CODE (dest
) == LABEL_DECL
)
1709 data
->last_goto
= stmt_p
;
1714 remove_useless_stmts_label (tree
*stmt_p
, struct rus_data
*data
)
1716 tree label
= LABEL_EXPR_LABEL (*stmt_p
);
1718 data
->has_label
= true;
1720 /* We do want to jump across non-local label receiver code. */
1721 if (DECL_NONLOCAL (label
))
1722 data
->last_goto
= NULL
;
1724 else if (data
->last_goto
&& GOTO_DESTINATION (*data
->last_goto
) == label
)
1726 *data
->last_goto
= build_empty_stmt ();
1727 data
->repeat
= true;
1730 /* ??? Add something here to delete unused labels. */
1734 /* If the function is "const" or "pure", then clear TREE_SIDE_EFFECTS on its
1735 decl. This allows us to eliminate redundant or useless
1736 calls to "const" functions.
1738 Gimplifier already does the same operation, but we may notice functions
1739 being const and pure once their calls has been gimplified, so we need
1740 to update the flag. */
1743 update_call_expr_flags (tree call
)
1745 tree decl
= get_callee_fndecl (call
);
1748 if (call_expr_flags (call
) & (ECF_CONST
| ECF_PURE
))
1749 TREE_SIDE_EFFECTS (call
) = 0;
1750 if (TREE_NOTHROW (decl
))
1751 TREE_NOTHROW (call
) = 1;
1755 /* T is CALL_EXPR. Set current_function_calls_* flags. */
1758 notice_special_calls (tree t
)
1760 int flags
= call_expr_flags (t
);
1762 if (flags
& ECF_MAY_BE_ALLOCA
)
1763 current_function_calls_alloca
= true;
1764 if (flags
& ECF_RETURNS_TWICE
)
1765 current_function_calls_setjmp
= true;
1769 /* Clear flags set by notice_special_calls. Used by dead code removal
1770 to update the flags. */
1773 clear_special_calls (void)
1775 current_function_calls_alloca
= false;
1776 current_function_calls_setjmp
= false;
1781 remove_useless_stmts_1 (tree
*tp
, struct rus_data
*data
)
1785 switch (TREE_CODE (t
))
1788 remove_useless_stmts_cond (tp
, data
);
1791 case TRY_FINALLY_EXPR
:
1792 remove_useless_stmts_tf (tp
, data
);
1795 case TRY_CATCH_EXPR
:
1796 remove_useless_stmts_tc (tp
, data
);
1800 remove_useless_stmts_bind (tp
, data
);
1804 remove_useless_stmts_goto (tp
, data
);
1808 remove_useless_stmts_label (tp
, data
);
1813 data
->last_goto
= NULL
;
1814 data
->may_branch
= true;
1819 data
->last_goto
= NULL
;
1820 notice_special_calls (t
);
1821 update_call_expr_flags (t
);
1822 if (tree_could_throw_p (t
))
1823 data
->may_throw
= true;
1827 data
->last_goto
= NULL
;
1829 op
= get_call_expr_in (t
);
1832 update_call_expr_flags (op
);
1833 notice_special_calls (op
);
1835 if (tree_could_throw_p (t
))
1836 data
->may_throw
= true;
1839 case STATEMENT_LIST
:
1841 tree_stmt_iterator i
= tsi_start (t
);
1842 while (!tsi_end_p (i
))
1845 if (IS_EMPTY_STMT (t
))
1851 remove_useless_stmts_1 (tsi_stmt_ptr (i
), data
);
1854 if (TREE_CODE (t
) == STATEMENT_LIST
)
1856 tsi_link_before (&i
, t
, TSI_SAME_STMT
);
1866 data
->last_goto
= NULL
;
1870 data
->last_goto
= NULL
;
1876 remove_useless_stmts (void)
1878 struct rus_data data
;
1880 clear_special_calls ();
1884 memset (&data
, 0, sizeof (data
));
1885 remove_useless_stmts_1 (&DECL_SAVED_TREE (current_function_decl
), &data
);
1887 while (data
.repeat
);
1891 struct tree_opt_pass pass_remove_useless_stmts
=
1893 "useless", /* name */
1895 remove_useless_stmts
, /* execute */
1898 0, /* static_pass_number */
1900 PROP_gimple_any
, /* properties_required */
1901 0, /* properties_provided */
1902 0, /* properties_destroyed */
1903 0, /* todo_flags_start */
1904 TODO_dump_func
, /* todo_flags_finish */
1909 /* Remove obviously useless statements in basic block BB. */
1912 cfg_remove_useless_stmts_bb (basic_block bb
)
1914 block_stmt_iterator bsi
;
1915 tree stmt
= NULL_TREE
;
1916 tree cond
, var
= NULL_TREE
, val
= NULL_TREE
;
1917 struct var_ann_d
*ann
;
1919 /* Check whether we come here from a condition, and if so, get the
1921 if (!single_pred_p (bb
)
1922 || !(single_pred_edge (bb
)->flags
1923 & (EDGE_TRUE_VALUE
| EDGE_FALSE_VALUE
)))
1926 cond
= COND_EXPR_COND (last_stmt (single_pred (bb
)));
1928 if (TREE_CODE (cond
) == VAR_DECL
|| TREE_CODE (cond
) == PARM_DECL
)
1931 val
= (single_pred_edge (bb
)->flags
& EDGE_FALSE_VALUE
1932 ? boolean_false_node
: boolean_true_node
);
1934 else if (TREE_CODE (cond
) == TRUTH_NOT_EXPR
1935 && (TREE_CODE (TREE_OPERAND (cond
, 0)) == VAR_DECL
1936 || TREE_CODE (TREE_OPERAND (cond
, 0)) == PARM_DECL
))
1938 var
= TREE_OPERAND (cond
, 0);
1939 val
= (single_pred_edge (bb
)->flags
& EDGE_FALSE_VALUE
1940 ? boolean_true_node
: boolean_false_node
);
1944 if (single_pred_edge (bb
)->flags
& EDGE_FALSE_VALUE
)
1945 cond
= invert_truthvalue (cond
);
1946 if (TREE_CODE (cond
) == EQ_EXPR
1947 && (TREE_CODE (TREE_OPERAND (cond
, 0)) == VAR_DECL
1948 || TREE_CODE (TREE_OPERAND (cond
, 0)) == PARM_DECL
)
1949 && (TREE_CODE (TREE_OPERAND (cond
, 1)) == VAR_DECL
1950 || TREE_CODE (TREE_OPERAND (cond
, 1)) == PARM_DECL
1951 || TREE_CONSTANT (TREE_OPERAND (cond
, 1))))
1953 var
= TREE_OPERAND (cond
, 0);
1954 val
= TREE_OPERAND (cond
, 1);
1960 /* Only work for normal local variables. */
1961 ann
= var_ann (var
);
1964 || TREE_ADDRESSABLE (var
))
1967 if (! TREE_CONSTANT (val
))
1969 ann
= var_ann (val
);
1972 || TREE_ADDRESSABLE (val
))
1976 /* Ignore floating point variables, since comparison behaves weird for
1978 if (FLOAT_TYPE_P (TREE_TYPE (var
)))
1981 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
);)
1983 stmt
= bsi_stmt (bsi
);
1985 /* If the THEN/ELSE clause merely assigns a value to a variable/parameter
1986 which is already known to contain that value, then remove the useless
1987 THEN/ELSE clause. */
1988 if (TREE_CODE (stmt
) == MODIFY_EXPR
1989 && TREE_OPERAND (stmt
, 0) == var
1990 && operand_equal_p (val
, TREE_OPERAND (stmt
, 1), 0))
1996 /* Invalidate the var if we encounter something that could modify it.
1997 Likewise for the value it was previously set to. Note that we only
1998 consider values that are either a VAR_DECL or PARM_DECL so we
1999 can test for conflict very simply. */
2000 if (TREE_CODE (stmt
) == ASM_EXPR
2001 || (TREE_CODE (stmt
) == MODIFY_EXPR
2002 && (TREE_OPERAND (stmt
, 0) == var
2003 || TREE_OPERAND (stmt
, 0) == val
)))
2011 /* A CFG-aware version of remove_useless_stmts. */
2014 cfg_remove_useless_stmts (void)
2018 #ifdef ENABLE_CHECKING
2019 verify_flow_info ();
2024 cfg_remove_useless_stmts_bb (bb
);
2029 /* Remove PHI nodes associated with basic block BB and all edges out of BB. */
2032 remove_phi_nodes_and_edges_for_unreachable_block (basic_block bb
)
2036 /* Since this block is no longer reachable, we can just delete all
2037 of its PHI nodes. */
2038 phi
= phi_nodes (bb
);
2041 tree next
= PHI_CHAIN (phi
);
2042 remove_phi_node (phi
, NULL_TREE
);
2046 /* Remove edges to BB's successors. */
2047 while (EDGE_COUNT (bb
->succs
) > 0)
2048 remove_edge (EDGE_SUCC (bb
, 0));
2052 /* Remove statements of basic block BB. */
2055 remove_bb (basic_block bb
)
2057 block_stmt_iterator i
;
2058 #ifdef USE_MAPPED_LOCATION
2059 source_location loc
= UNKNOWN_LOCATION
;
2061 source_locus loc
= 0;
2066 fprintf (dump_file
, "Removing basic block %d\n", bb
->index
);
2067 if (dump_flags
& TDF_DETAILS
)
2069 dump_bb (bb
, dump_file
, 0);
2070 fprintf (dump_file
, "\n");
2074 /* If we remove the header or the latch of a loop, mark the loop for
2075 removal by setting its header and latch to NULL. */
2078 struct loop
*loop
= bb
->loop_father
;
2080 if (loop
->latch
== bb
2081 || loop
->header
== bb
)
2084 loop
->header
= NULL
;
2088 /* Remove all the instructions in the block. */
2089 for (i
= bsi_start (bb
); !bsi_end_p (i
);)
2091 tree stmt
= bsi_stmt (i
);
2092 if (TREE_CODE (stmt
) == LABEL_EXPR
2093 && FORCED_LABEL (LABEL_EXPR_LABEL (stmt
)))
2095 basic_block new_bb
= bb
->prev_bb
;
2096 block_stmt_iterator new_bsi
= bsi_start (new_bb
);
2099 bsi_insert_before (&new_bsi
, stmt
, BSI_NEW_STMT
);
2103 release_defs (stmt
);
2105 set_bb_for_stmt (stmt
, NULL
);
2109 /* Don't warn for removed gotos. Gotos are often removed due to
2110 jump threading, thus resulting in bogus warnings. Not great,
2111 since this way we lose warnings for gotos in the original
2112 program that are indeed unreachable. */
2113 if (TREE_CODE (stmt
) != GOTO_EXPR
&& EXPR_HAS_LOCATION (stmt
) && !loc
)
2115 #ifdef USE_MAPPED_LOCATION
2116 if (EXPR_HAS_LOCATION (stmt
))
2117 loc
= EXPR_LOCATION (stmt
);
2120 t
= EXPR_LOCUS (stmt
);
2121 if (t
&& LOCATION_LINE (*t
) > 0)
2127 /* If requested, give a warning that the first statement in the
2128 block is unreachable. We walk statements backwards in the
2129 loop above, so the last statement we process is the first statement
2131 #ifdef USE_MAPPED_LOCATION
2132 if (warn_notreached
&& loc
> BUILTINS_LOCATION
)
2133 warning ("%Hwill never be executed", &loc
);
2135 if (warn_notreached
&& loc
)
2136 warning ("%Hwill never be executed", loc
);
2139 remove_phi_nodes_and_edges_for_unreachable_block (bb
);
2142 /* A list of all the noreturn calls passed to modify_stmt.
2143 cleanup_control_flow uses it to detect cases where a mid-block
2144 indirect call has been turned into a noreturn call. When this
2145 happens, all the instructions after the call are no longer
2146 reachable and must be deleted as dead. */
2148 VEC(tree
) *modified_noreturn_calls
;
2150 /* Try to remove superfluous control structures. */
2153 cleanup_control_flow (void)
2156 block_stmt_iterator bsi
;
2157 bool retval
= false;
2160 /* Detect cases where a mid-block call is now known not to return. */
2161 while (VEC_length (tree
, modified_noreturn_calls
))
2163 stmt
= VEC_pop (tree
, modified_noreturn_calls
);
2164 bb
= bb_for_stmt (stmt
);
2165 if (bb
!= NULL
&& last_stmt (bb
) != stmt
&& noreturn_call_p (stmt
))
2166 split_block (bb
, stmt
);
2171 bsi
= bsi_last (bb
);
2173 if (bsi_end_p (bsi
))
2176 stmt
= bsi_stmt (bsi
);
2177 if (TREE_CODE (stmt
) == COND_EXPR
2178 || TREE_CODE (stmt
) == SWITCH_EXPR
)
2179 retval
|= cleanup_control_expr_graph (bb
, bsi
);
2181 /* If we had a computed goto which has a compile-time determinable
2182 destination, then we can eliminate the goto. */
2183 if (TREE_CODE (stmt
) == GOTO_EXPR
2184 && TREE_CODE (GOTO_DESTINATION (stmt
)) == ADDR_EXPR
2185 && TREE_CODE (TREE_OPERAND (GOTO_DESTINATION (stmt
), 0)) == LABEL_DECL
)
2190 basic_block target_block
;
2191 bool removed_edge
= false;
2193 /* First look at all the outgoing edges. Delete any outgoing
2194 edges which do not go to the right block. For the one
2195 edge which goes to the right block, fix up its flags. */
2196 label
= TREE_OPERAND (GOTO_DESTINATION (stmt
), 0);
2197 target_block
= label_to_block (label
);
2198 for (ei
= ei_start (bb
->succs
); (e
= ei_safe_edge (ei
)); )
2200 if (e
->dest
!= target_block
)
2202 removed_edge
= true;
2207 /* Turn off the EDGE_ABNORMAL flag. */
2208 e
->flags
&= ~EDGE_ABNORMAL
;
2210 /* And set EDGE_FALLTHRU. */
2211 e
->flags
|= EDGE_FALLTHRU
;
2216 /* If we removed one or more edges, then we will need to fix the
2217 dominators. It may be possible to incrementally update them. */
2219 free_dominance_info (CDI_DOMINATORS
);
2221 /* Remove the GOTO_EXPR as it is not needed. The CFG has all the
2222 relevant information we need. */
2227 /* Check for indirect calls that have been turned into
2229 if (noreturn_call_p (stmt
) && remove_fallthru_edge (bb
->succs
))
2231 free_dominance_info (CDI_DOMINATORS
);
2239 /* Disconnect an unreachable block in the control expression starting
2243 cleanup_control_expr_graph (basic_block bb
, block_stmt_iterator bsi
)
2246 bool retval
= false;
2247 tree expr
= bsi_stmt (bsi
), val
;
2249 if (!single_succ_p (bb
))
2254 switch (TREE_CODE (expr
))
2257 val
= COND_EXPR_COND (expr
);
2261 val
= SWITCH_COND (expr
);
2262 if (TREE_CODE (val
) != INTEGER_CST
)
2270 taken_edge
= find_taken_edge (bb
, val
);
2274 /* Remove all the edges except the one that is always executed. */
2275 for (ei
= ei_start (bb
->succs
); (e
= ei_safe_edge (ei
)); )
2277 if (e
!= taken_edge
)
2279 taken_edge
->probability
+= e
->probability
;
2280 taken_edge
->count
+= e
->count
;
2287 if (taken_edge
->probability
> REG_BR_PROB_BASE
)
2288 taken_edge
->probability
= REG_BR_PROB_BASE
;
2291 taken_edge
= single_succ_edge (bb
);
2294 taken_edge
->flags
= EDGE_FALLTHRU
;
2296 /* We removed some paths from the cfg. */
2297 free_dominance_info (CDI_DOMINATORS
);
2302 /* Remove any fallthru edge from EV. Return true if an edge was removed. */
2305 remove_fallthru_edge (VEC(edge
) *ev
)
2310 FOR_EACH_EDGE (e
, ei
, ev
)
2311 if ((e
->flags
& EDGE_FALLTHRU
) != 0)
2319 /* Given a basic block BB ending with COND_EXPR or SWITCH_EXPR, and a
2320 predicate VAL, return the edge that will be taken out of the block.
2321 If VAL does not match a unique edge, NULL is returned. */
2324 find_taken_edge (basic_block bb
, tree val
)
2328 stmt
= last_stmt (bb
);
2331 gcc_assert (is_ctrl_stmt (stmt
));
2334 if (! is_gimple_min_invariant (val
))
2337 if (TREE_CODE (stmt
) == COND_EXPR
)
2338 return find_taken_edge_cond_expr (bb
, val
);
2340 if (TREE_CODE (stmt
) == SWITCH_EXPR
)
2341 return find_taken_edge_switch_expr (bb
, val
);
2343 if (computed_goto_p (stmt
))
2344 return find_taken_edge_computed_goto (bb
, TREE_OPERAND( val
, 0));
2349 /* Given a constant value VAL and the entry block BB to a GOTO_EXPR
2350 statement, determine which of the outgoing edges will be taken out of the
2351 block. Return NULL if either edge may be taken. */
2354 find_taken_edge_computed_goto (basic_block bb
, tree val
)
2359 dest
= label_to_block (val
);
2362 e
= find_edge (bb
, dest
);
2363 gcc_assert (e
!= NULL
);
2369 /* Given a constant value VAL and the entry block BB to a COND_EXPR
2370 statement, determine which of the two edges will be taken out of the
2371 block. Return NULL if either edge may be taken. */
2374 find_taken_edge_cond_expr (basic_block bb
, tree val
)
2376 edge true_edge
, false_edge
;
2378 extract_true_false_edges_from_block (bb
, &true_edge
, &false_edge
);
2380 gcc_assert (TREE_CODE (val
) == INTEGER_CST
);
2381 return (zero_p (val
) ? false_edge
: true_edge
);
2384 /* Given an INTEGER_CST VAL and the entry block BB to a SWITCH_EXPR
2385 statement, determine which edge will be taken out of the block. Return
2386 NULL if any edge may be taken. */
2389 find_taken_edge_switch_expr (basic_block bb
, tree val
)
2391 tree switch_expr
, taken_case
;
2392 basic_block dest_bb
;
2395 switch_expr
= last_stmt (bb
);
2396 taken_case
= find_case_label_for_value (switch_expr
, val
);
2397 dest_bb
= label_to_block (CASE_LABEL (taken_case
));
2399 e
= find_edge (bb
, dest_bb
);
2405 /* Return the CASE_LABEL_EXPR that SWITCH_EXPR will take for VAL.
2406 We can make optimal use here of the fact that the case labels are
2407 sorted: We can do a binary search for a case matching VAL. */
2410 find_case_label_for_value (tree switch_expr
, tree val
)
2412 tree vec
= SWITCH_LABELS (switch_expr
);
2413 size_t low
, high
, n
= TREE_VEC_LENGTH (vec
);
2414 tree default_case
= TREE_VEC_ELT (vec
, n
- 1);
2416 for (low
= -1, high
= n
- 1; high
- low
> 1; )
2418 size_t i
= (high
+ low
) / 2;
2419 tree t
= TREE_VEC_ELT (vec
, i
);
2422 /* Cache the result of comparing CASE_LOW and val. */
2423 cmp
= tree_int_cst_compare (CASE_LOW (t
), val
);
2430 if (CASE_HIGH (t
) == NULL
)
2432 /* A singe-valued case label. */
2438 /* A case range. We can only handle integer ranges. */
2439 if (cmp
<= 0 && tree_int_cst_compare (CASE_HIGH (t
), val
) >= 0)
2444 return default_case
;
2448 /* If all the PHI nodes in DEST have alternatives for E1 and E2 and
2449 those alternatives are equal in each of the PHI nodes, then return
2450 true, else return false. */
2453 phi_alternatives_equal (basic_block dest
, edge e1
, edge e2
)
2455 int n1
= e1
->dest_idx
;
2456 int n2
= e2
->dest_idx
;
2459 for (phi
= phi_nodes (dest
); phi
; phi
= PHI_CHAIN (phi
))
2461 tree val1
= PHI_ARG_DEF (phi
, n1
);
2462 tree val2
= PHI_ARG_DEF (phi
, n2
);
2464 gcc_assert (val1
!= NULL_TREE
);
2465 gcc_assert (val2
!= NULL_TREE
);
2467 if (!operand_equal_for_phi_arg_p (val1
, val2
))
2475 /*---------------------------------------------------------------------------
2477 ---------------------------------------------------------------------------*/
2479 /* Dump tree-specific information of block BB to file OUTF. */
2482 tree_dump_bb (basic_block bb
, FILE *outf
, int indent
)
2484 dump_generic_bb (outf
, bb
, indent
, TDF_VOPS
);
2488 /* Dump a basic block on stderr. */
2491 debug_tree_bb (basic_block bb
)
2493 dump_bb (bb
, stderr
, 0);
2497 /* Dump basic block with index N on stderr. */
2500 debug_tree_bb_n (int n
)
2502 debug_tree_bb (BASIC_BLOCK (n
));
2503 return BASIC_BLOCK (n
);
2507 /* Dump the CFG on stderr.
2509 FLAGS are the same used by the tree dumping functions
2510 (see TDF_* in tree.h). */
2513 debug_tree_cfg (int flags
)
2515 dump_tree_cfg (stderr
, flags
);
2519 /* Dump the program showing basic block boundaries on the given FILE.
2521 FLAGS are the same used by the tree dumping functions (see TDF_* in
2525 dump_tree_cfg (FILE *file
, int flags
)
2527 if (flags
& TDF_DETAILS
)
2529 const char *funcname
2530 = lang_hooks
.decl_printable_name (current_function_decl
, 2);
2533 fprintf (file
, ";; Function %s\n\n", funcname
);
2534 fprintf (file
, ";; \n%d basic blocks, %d edges, last basic block %d.\n\n",
2535 n_basic_blocks
, n_edges
, last_basic_block
);
2537 brief_dump_cfg (file
);
2538 fprintf (file
, "\n");
2541 if (flags
& TDF_STATS
)
2542 dump_cfg_stats (file
);
2544 dump_function_to_file (current_function_decl
, file
, flags
| TDF_BLOCKS
);
2548 /* Dump CFG statistics on FILE. */
2551 dump_cfg_stats (FILE *file
)
2553 static long max_num_merged_labels
= 0;
2554 unsigned long size
, total
= 0;
2557 const char * const fmt_str
= "%-30s%-13s%12s\n";
2558 const char * const fmt_str_1
= "%-30s%13d%11lu%c\n";
2559 const char * const fmt_str_3
= "%-43s%11lu%c\n";
2560 const char *funcname
2561 = lang_hooks
.decl_printable_name (current_function_decl
, 2);
2564 fprintf (file
, "\nCFG Statistics for %s\n\n", funcname
);
2566 fprintf (file
, "---------------------------------------------------------\n");
2567 fprintf (file
, fmt_str
, "", " Number of ", "Memory");
2568 fprintf (file
, fmt_str
, "", " instances ", "used ");
2569 fprintf (file
, "---------------------------------------------------------\n");
2571 size
= n_basic_blocks
* sizeof (struct basic_block_def
);
2573 fprintf (file
, fmt_str_1
, "Basic blocks", n_basic_blocks
,
2574 SCALE (size
), LABEL (size
));
2578 n_edges
+= EDGE_COUNT (bb
->succs
);
2579 size
= n_edges
* sizeof (struct edge_def
);
2581 fprintf (file
, fmt_str_1
, "Edges", n_edges
, SCALE (size
), LABEL (size
));
2583 size
= n_basic_blocks
* sizeof (struct bb_ann_d
);
2585 fprintf (file
, fmt_str_1
, "Basic block annotations", n_basic_blocks
,
2586 SCALE (size
), LABEL (size
));
2588 fprintf (file
, "---------------------------------------------------------\n");
2589 fprintf (file
, fmt_str_3
, "Total memory used by CFG data", SCALE (total
),
2591 fprintf (file
, "---------------------------------------------------------\n");
2592 fprintf (file
, "\n");
2594 if (cfg_stats
.num_merged_labels
> max_num_merged_labels
)
2595 max_num_merged_labels
= cfg_stats
.num_merged_labels
;
2597 fprintf (file
, "Coalesced label blocks: %ld (Max so far: %ld)\n",
2598 cfg_stats
.num_merged_labels
, max_num_merged_labels
);
2600 fprintf (file
, "\n");
2604 /* Dump CFG statistics on stderr. Keep extern so that it's always
2605 linked in the final executable. */
2608 debug_cfg_stats (void)
2610 dump_cfg_stats (stderr
);
2614 /* Dump the flowgraph to a .vcg FILE. */
2617 tree_cfg2vcg (FILE *file
)
2622 const char *funcname
2623 = lang_hooks
.decl_printable_name (current_function_decl
, 2);
2625 /* Write the file header. */
2626 fprintf (file
, "graph: { title: \"%s\"\n", funcname
);
2627 fprintf (file
, "node: { title: \"ENTRY\" label: \"ENTRY\" }\n");
2628 fprintf (file
, "node: { title: \"EXIT\" label: \"EXIT\" }\n");
2630 /* Write blocks and edges. */
2631 FOR_EACH_EDGE (e
, ei
, ENTRY_BLOCK_PTR
->succs
)
2633 fprintf (file
, "edge: { sourcename: \"ENTRY\" targetname: \"%d\"",
2636 if (e
->flags
& EDGE_FAKE
)
2637 fprintf (file
, " linestyle: dotted priority: 10");
2639 fprintf (file
, " linestyle: solid priority: 100");
2641 fprintf (file
, " }\n");
2647 enum tree_code head_code
, end_code
;
2648 const char *head_name
, *end_name
;
2651 tree first
= first_stmt (bb
);
2652 tree last
= last_stmt (bb
);
2656 head_code
= TREE_CODE (first
);
2657 head_name
= tree_code_name
[head_code
];
2658 head_line
= get_lineno (first
);
2661 head_name
= "no-statement";
2665 end_code
= TREE_CODE (last
);
2666 end_name
= tree_code_name
[end_code
];
2667 end_line
= get_lineno (last
);
2670 end_name
= "no-statement";
2672 fprintf (file
, "node: { title: \"%d\" label: \"#%d\\n%s (%d)\\n%s (%d)\"}\n",
2673 bb
->index
, bb
->index
, head_name
, head_line
, end_name
,
2676 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
2678 if (e
->dest
== EXIT_BLOCK_PTR
)
2679 fprintf (file
, "edge: { sourcename: \"%d\" targetname: \"EXIT\"", bb
->index
);
2681 fprintf (file
, "edge: { sourcename: \"%d\" targetname: \"%d\"", bb
->index
, e
->dest
->index
);
2683 if (e
->flags
& EDGE_FAKE
)
2684 fprintf (file
, " priority: 10 linestyle: dotted");
2686 fprintf (file
, " priority: 100 linestyle: solid");
2688 fprintf (file
, " }\n");
2691 if (bb
->next_bb
!= EXIT_BLOCK_PTR
)
2695 fputs ("}\n\n", file
);
2700 /*---------------------------------------------------------------------------
2701 Miscellaneous helpers
2702 ---------------------------------------------------------------------------*/
2704 /* Return true if T represents a stmt that always transfers control. */
2707 is_ctrl_stmt (tree t
)
2709 return (TREE_CODE (t
) == COND_EXPR
2710 || TREE_CODE (t
) == SWITCH_EXPR
2711 || TREE_CODE (t
) == GOTO_EXPR
2712 || TREE_CODE (t
) == RETURN_EXPR
2713 || TREE_CODE (t
) == RESX_EXPR
);
2717 /* Return true if T is a statement that may alter the flow of control
2718 (e.g., a call to a non-returning function). */
2721 is_ctrl_altering_stmt (tree t
)
2726 call
= get_call_expr_in (t
);
2729 /* A non-pure/const CALL_EXPR alters flow control if the current
2730 function has nonlocal labels. */
2731 if (TREE_SIDE_EFFECTS (call
) && current_function_has_nonlocal_label
)
2734 /* A CALL_EXPR also alters control flow if it does not return. */
2735 if (call_expr_flags (call
) & ECF_NORETURN
)
2739 /* If a statement can throw, it alters control flow. */
2740 return tree_can_throw_internal (t
);
2744 /* Return true if T is a computed goto. */
2747 computed_goto_p (tree t
)
2749 return (TREE_CODE (t
) == GOTO_EXPR
2750 && TREE_CODE (GOTO_DESTINATION (t
)) != LABEL_DECL
);
2754 /* Checks whether EXPR is a simple local goto. */
2757 simple_goto_p (tree expr
)
2759 return (TREE_CODE (expr
) == GOTO_EXPR
2760 && TREE_CODE (GOTO_DESTINATION (expr
)) == LABEL_DECL
);
2764 /* Return true if T should start a new basic block. PREV_T is the
2765 statement preceding T. It is used when T is a label or a case label.
2766 Labels should only start a new basic block if their previous statement
2767 wasn't a label. Otherwise, sequence of labels would generate
2768 unnecessary basic blocks that only contain a single label. */
2771 stmt_starts_bb_p (tree t
, tree prev_t
)
2776 /* LABEL_EXPRs start a new basic block only if the preceding
2777 statement wasn't a label of the same type. This prevents the
2778 creation of consecutive blocks that have nothing but a single
2780 if (TREE_CODE (t
) == LABEL_EXPR
)
2782 /* Nonlocal and computed GOTO targets always start a new block. */
2783 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (t
))
2784 || FORCED_LABEL (LABEL_EXPR_LABEL (t
)))
2787 if (prev_t
&& TREE_CODE (prev_t
) == LABEL_EXPR
)
2789 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (prev_t
)))
2792 cfg_stats
.num_merged_labels
++;
2803 /* Return true if T should end a basic block. */
2806 stmt_ends_bb_p (tree t
)
2808 return is_ctrl_stmt (t
) || is_ctrl_altering_stmt (t
);
2812 /* Add gotos that used to be represented implicitly in the CFG. */
2815 disband_implicit_edges (void)
2818 block_stmt_iterator last
;
2825 last
= bsi_last (bb
);
2826 stmt
= last_stmt (bb
);
2828 if (stmt
&& TREE_CODE (stmt
) == COND_EXPR
)
2830 /* Remove superfluous gotos from COND_EXPR branches. Moved
2831 from cfg_remove_useless_stmts here since it violates the
2832 invariants for tree--cfg correspondence and thus fits better
2833 here where we do it anyway. */
2834 e
= find_edge (bb
, bb
->next_bb
);
2837 if (e
->flags
& EDGE_TRUE_VALUE
)
2838 COND_EXPR_THEN (stmt
) = build_empty_stmt ();
2839 else if (e
->flags
& EDGE_FALSE_VALUE
)
2840 COND_EXPR_ELSE (stmt
) = build_empty_stmt ();
2843 e
->flags
|= EDGE_FALLTHRU
;
2849 if (stmt
&& TREE_CODE (stmt
) == RETURN_EXPR
)
2851 /* Remove the RETURN_EXPR if we may fall though to the exit
2853 gcc_assert (single_succ_p (bb
));
2854 gcc_assert (single_succ (bb
) == EXIT_BLOCK_PTR
);
2856 if (bb
->next_bb
== EXIT_BLOCK_PTR
2857 && !TREE_OPERAND (stmt
, 0))
2860 single_succ_edge (bb
)->flags
|= EDGE_FALLTHRU
;
2865 /* There can be no fallthru edge if the last statement is a control
2867 if (stmt
&& is_ctrl_stmt (stmt
))
2870 /* Find a fallthru edge and emit the goto if necessary. */
2871 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
2872 if (e
->flags
& EDGE_FALLTHRU
)
2875 if (!e
|| e
->dest
== bb
->next_bb
)
2878 gcc_assert (e
->dest
!= EXIT_BLOCK_PTR
);
2879 label
= tree_block_label (e
->dest
);
2881 stmt
= build1 (GOTO_EXPR
, void_type_node
, label
);
2882 #ifdef USE_MAPPED_LOCATION
2883 SET_EXPR_LOCATION (stmt
, e
->goto_locus
);
2885 SET_EXPR_LOCUS (stmt
, e
->goto_locus
);
2887 bsi_insert_after (&last
, stmt
, BSI_NEW_STMT
);
2888 e
->flags
&= ~EDGE_FALLTHRU
;
2892 /* Remove block annotations and other datastructures. */
2895 delete_tree_cfg_annotations (void)
2898 if (n_basic_blocks
> 0)
2899 free_blocks_annotations ();
2901 label_to_block_map
= NULL
;
2908 /* Return the first statement in basic block BB. */
2911 first_stmt (basic_block bb
)
2913 block_stmt_iterator i
= bsi_start (bb
);
2914 return !bsi_end_p (i
) ? bsi_stmt (i
) : NULL_TREE
;
2918 /* Return the last statement in basic block BB. */
2921 last_stmt (basic_block bb
)
2923 block_stmt_iterator b
= bsi_last (bb
);
2924 return !bsi_end_p (b
) ? bsi_stmt (b
) : NULL_TREE
;
2928 /* Return a pointer to the last statement in block BB. */
2931 last_stmt_ptr (basic_block bb
)
2933 block_stmt_iterator last
= bsi_last (bb
);
2934 return !bsi_end_p (last
) ? bsi_stmt_ptr (last
) : NULL
;
2938 /* Return the last statement of an otherwise empty block. Return NULL
2939 if the block is totally empty, or if it contains more than one
2943 last_and_only_stmt (basic_block bb
)
2945 block_stmt_iterator i
= bsi_last (bb
);
2951 last
= bsi_stmt (i
);
2956 /* Empty statements should no longer appear in the instruction stream.
2957 Everything that might have appeared before should be deleted by
2958 remove_useless_stmts, and the optimizers should just bsi_remove
2959 instead of smashing with build_empty_stmt.
2961 Thus the only thing that should appear here in a block containing
2962 one executable statement is a label. */
2963 prev
= bsi_stmt (i
);
2964 if (TREE_CODE (prev
) == LABEL_EXPR
)
2971 /* Mark BB as the basic block holding statement T. */
2974 set_bb_for_stmt (tree t
, basic_block bb
)
2976 if (TREE_CODE (t
) == PHI_NODE
)
2978 else if (TREE_CODE (t
) == STATEMENT_LIST
)
2980 tree_stmt_iterator i
;
2981 for (i
= tsi_start (t
); !tsi_end_p (i
); tsi_next (&i
))
2982 set_bb_for_stmt (tsi_stmt (i
), bb
);
2986 stmt_ann_t ann
= get_stmt_ann (t
);
2989 /* If the statement is a label, add the label to block-to-labels map
2990 so that we can speed up edge creation for GOTO_EXPRs. */
2991 if (TREE_CODE (t
) == LABEL_EXPR
)
2995 t
= LABEL_EXPR_LABEL (t
);
2996 uid
= LABEL_DECL_UID (t
);
2999 LABEL_DECL_UID (t
) = uid
= cfun
->last_label_uid
++;
3000 if (VARRAY_SIZE (label_to_block_map
) <= (unsigned) uid
)
3001 VARRAY_GROW (label_to_block_map
, 3 * uid
/ 2);
3004 /* We're moving an existing label. Make sure that we've
3005 removed it from the old block. */
3006 gcc_assert (!bb
|| !VARRAY_BB (label_to_block_map
, uid
));
3007 VARRAY_BB (label_to_block_map
, uid
) = bb
;
3012 /* Finds iterator for STMT. */
3014 extern block_stmt_iterator
3015 bsi_for_stmt (tree stmt
)
3017 block_stmt_iterator bsi
;
3019 for (bsi
= bsi_start (bb_for_stmt (stmt
)); !bsi_end_p (bsi
); bsi_next (&bsi
))
3020 if (bsi_stmt (bsi
) == stmt
)
3026 /* Mark statement T as modified, and update it. */
3028 update_modified_stmts (tree t
)
3030 if (TREE_CODE (t
) == STATEMENT_LIST
)
3032 tree_stmt_iterator i
;
3034 for (i
= tsi_start (t
); !tsi_end_p (i
); tsi_next (&i
))
3036 stmt
= tsi_stmt (i
);
3037 update_stmt_if_modified (stmt
);
3041 update_stmt_if_modified (t
);
3044 /* Insert statement (or statement list) T before the statement
3045 pointed-to by iterator I. M specifies how to update iterator I
3046 after insertion (see enum bsi_iterator_update). */
3049 bsi_insert_before (block_stmt_iterator
*i
, tree t
, enum bsi_iterator_update m
)
3051 set_bb_for_stmt (t
, i
->bb
);
3052 update_modified_stmts (t
);
3053 tsi_link_before (&i
->tsi
, t
, m
);
3057 /* Insert statement (or statement list) T after the statement
3058 pointed-to by iterator I. M specifies how to update iterator I
3059 after insertion (see enum bsi_iterator_update). */
3062 bsi_insert_after (block_stmt_iterator
*i
, tree t
, enum bsi_iterator_update m
)
3064 set_bb_for_stmt (t
, i
->bb
);
3065 update_modified_stmts (t
);
3066 tsi_link_after (&i
->tsi
, t
, m
);
3070 /* Remove the statement pointed to by iterator I. The iterator is updated
3071 to the next statement. */
3074 bsi_remove (block_stmt_iterator
*i
)
3076 tree t
= bsi_stmt (*i
);
3077 set_bb_for_stmt (t
, NULL
);
3078 delink_stmt_imm_use (t
);
3079 tsi_delink (&i
->tsi
);
3080 mark_stmt_modified (t
);
3084 /* Move the statement at FROM so it comes right after the statement at TO. */
3087 bsi_move_after (block_stmt_iterator
*from
, block_stmt_iterator
*to
)
3089 tree stmt
= bsi_stmt (*from
);
3091 bsi_insert_after (to
, stmt
, BSI_SAME_STMT
);
3095 /* Move the statement at FROM so it comes right before the statement at TO. */
3098 bsi_move_before (block_stmt_iterator
*from
, block_stmt_iterator
*to
)
3100 tree stmt
= bsi_stmt (*from
);
3102 bsi_insert_before (to
, stmt
, BSI_SAME_STMT
);
3106 /* Move the statement at FROM to the end of basic block BB. */
3109 bsi_move_to_bb_end (block_stmt_iterator
*from
, basic_block bb
)
3111 block_stmt_iterator last
= bsi_last (bb
);
3113 /* Have to check bsi_end_p because it could be an empty block. */
3114 if (!bsi_end_p (last
) && is_ctrl_stmt (bsi_stmt (last
)))
3115 bsi_move_before (from
, &last
);
3117 bsi_move_after (from
, &last
);
3121 /* Replace the contents of the statement pointed to by iterator BSI
3122 with STMT. If PRESERVE_EH_INFO is true, the exception handling
3123 information of the original statement is preserved. */
3126 bsi_replace (const block_stmt_iterator
*bsi
, tree stmt
, bool preserve_eh_info
)
3129 tree orig_stmt
= bsi_stmt (*bsi
);
3131 SET_EXPR_LOCUS (stmt
, EXPR_LOCUS (orig_stmt
));
3132 set_bb_for_stmt (stmt
, bsi
->bb
);
3134 /* Preserve EH region information from the original statement, if
3135 requested by the caller. */
3136 if (preserve_eh_info
)
3138 eh_region
= lookup_stmt_eh_region (orig_stmt
);
3140 add_stmt_to_eh_region (stmt
, eh_region
);
3143 *bsi_stmt_ptr (*bsi
) = stmt
;
3144 mark_stmt_modified (stmt
);
3145 update_modified_stmts (stmt
);
3149 /* Insert the statement pointed-to by BSI into edge E. Every attempt
3150 is made to place the statement in an existing basic block, but
3151 sometimes that isn't possible. When it isn't possible, the edge is
3152 split and the statement is added to the new block.
3154 In all cases, the returned *BSI points to the correct location. The
3155 return value is true if insertion should be done after the location,
3156 or false if it should be done before the location. If new basic block
3157 has to be created, it is stored in *NEW_BB. */
3160 tree_find_edge_insert_loc (edge e
, block_stmt_iterator
*bsi
,
3161 basic_block
*new_bb
)
3163 basic_block dest
, src
;
3169 /* If the destination has one predecessor which has no PHI nodes,
3170 insert there. Except for the exit block.
3172 The requirement for no PHI nodes could be relaxed. Basically we
3173 would have to examine the PHIs to prove that none of them used
3174 the value set by the statement we want to insert on E. That
3175 hardly seems worth the effort. */
3176 if (single_pred_p (dest
)
3177 && ! phi_nodes (dest
)
3178 && dest
!= EXIT_BLOCK_PTR
)
3180 *bsi
= bsi_start (dest
);
3181 if (bsi_end_p (*bsi
))
3184 /* Make sure we insert after any leading labels. */
3185 tmp
= bsi_stmt (*bsi
);
3186 while (TREE_CODE (tmp
) == LABEL_EXPR
)
3189 if (bsi_end_p (*bsi
))
3191 tmp
= bsi_stmt (*bsi
);
3194 if (bsi_end_p (*bsi
))
3196 *bsi
= bsi_last (dest
);
3203 /* If the source has one successor, the edge is not abnormal and
3204 the last statement does not end a basic block, insert there.
3205 Except for the entry block. */
3207 if ((e
->flags
& EDGE_ABNORMAL
) == 0
3208 && single_succ_p (src
)
3209 && src
!= ENTRY_BLOCK_PTR
)
3211 *bsi
= bsi_last (src
);
3212 if (bsi_end_p (*bsi
))
3215 tmp
= bsi_stmt (*bsi
);
3216 if (!stmt_ends_bb_p (tmp
))
3219 /* Insert code just before returning the value. We may need to decompose
3220 the return in the case it contains non-trivial operand. */
3221 if (TREE_CODE (tmp
) == RETURN_EXPR
)
3223 tree op
= TREE_OPERAND (tmp
, 0);
3224 if (!is_gimple_val (op
))
3226 gcc_assert (TREE_CODE (op
) == MODIFY_EXPR
);
3227 bsi_insert_before (bsi
, op
, BSI_NEW_STMT
);
3228 TREE_OPERAND (tmp
, 0) = TREE_OPERAND (op
, 0);
3235 /* Otherwise, create a new basic block, and split this edge. */
3236 dest
= split_edge (e
);
3239 e
= single_pred_edge (dest
);
3244 /* This routine will commit all pending edge insertions, creating any new
3245 basic blocks which are necessary. */
3248 bsi_commit_edge_inserts (void)
3254 bsi_commit_one_edge_insert (single_succ_edge (ENTRY_BLOCK_PTR
), NULL
);
3257 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
3258 bsi_commit_one_edge_insert (e
, NULL
);
3262 /* Commit insertions pending at edge E. If a new block is created, set NEW_BB
3263 to this block, otherwise set it to NULL. */
3266 bsi_commit_one_edge_insert (edge e
, basic_block
*new_bb
)
3270 if (PENDING_STMT (e
))
3272 block_stmt_iterator bsi
;
3273 tree stmt
= PENDING_STMT (e
);
3275 PENDING_STMT (e
) = NULL_TREE
;
3277 if (tree_find_edge_insert_loc (e
, &bsi
, new_bb
))
3278 bsi_insert_after (&bsi
, stmt
, BSI_NEW_STMT
);
3280 bsi_insert_before (&bsi
, stmt
, BSI_NEW_STMT
);
3285 /* Add STMT to the pending list of edge E. No actual insertion is
3286 made until a call to bsi_commit_edge_inserts () is made. */
3289 bsi_insert_on_edge (edge e
, tree stmt
)
3291 append_to_statement_list (stmt
, &PENDING_STMT (e
));
3294 /* Similar to bsi_insert_on_edge+bsi_commit_edge_inserts. If a new
3295 block has to be created, it is returned. */
3298 bsi_insert_on_edge_immediate (edge e
, tree stmt
)
3300 block_stmt_iterator bsi
;
3301 basic_block new_bb
= NULL
;
3303 gcc_assert (!PENDING_STMT (e
));
3305 if (tree_find_edge_insert_loc (e
, &bsi
, &new_bb
))
3306 bsi_insert_after (&bsi
, stmt
, BSI_NEW_STMT
);
3308 bsi_insert_before (&bsi
, stmt
, BSI_NEW_STMT
);
3313 /*---------------------------------------------------------------------------
3314 Tree specific functions for CFG manipulation
3315 ---------------------------------------------------------------------------*/
3317 /* Reinstall those PHI arguments queued in OLD_EDGE to NEW_EDGE. */
3320 reinstall_phi_args (edge new_edge
, edge old_edge
)
3324 if (!PENDING_STMT (old_edge
))
3327 for (var
= PENDING_STMT (old_edge
), phi
= phi_nodes (new_edge
->dest
);
3329 var
= TREE_CHAIN (var
), phi
= PHI_CHAIN (phi
))
3331 tree result
= TREE_PURPOSE (var
);
3332 tree arg
= TREE_VALUE (var
);
3334 gcc_assert (result
== PHI_RESULT (phi
));
3336 add_phi_arg (phi
, arg
, new_edge
);
3339 PENDING_STMT (old_edge
) = NULL
;
3342 /* Split a (typically critical) edge EDGE_IN. Return the new block.
3343 Abort on abnormal edges. */
3346 tree_split_edge (edge edge_in
)
3348 basic_block new_bb
, after_bb
, dest
, src
;
3351 /* Abnormal edges cannot be split. */
3352 gcc_assert (!(edge_in
->flags
& EDGE_ABNORMAL
));
3355 dest
= edge_in
->dest
;
3357 /* Place the new block in the block list. Try to keep the new block
3358 near its "logical" location. This is of most help to humans looking
3359 at debugging dumps. */
3360 if (dest
->prev_bb
&& find_edge (dest
->prev_bb
, dest
))
3361 after_bb
= edge_in
->src
;
3363 after_bb
= dest
->prev_bb
;
3365 new_bb
= create_empty_bb (after_bb
);
3366 new_bb
->frequency
= EDGE_FREQUENCY (edge_in
);
3367 new_bb
->count
= edge_in
->count
;
3368 new_edge
= make_edge (new_bb
, dest
, EDGE_FALLTHRU
);
3369 new_edge
->probability
= REG_BR_PROB_BASE
;
3370 new_edge
->count
= edge_in
->count
;
3372 e
= redirect_edge_and_branch (edge_in
, new_bb
);
3374 reinstall_phi_args (new_edge
, e
);
3380 /* Return true when BB has label LABEL in it. */
3383 has_label_p (basic_block bb
, tree label
)
3385 block_stmt_iterator bsi
;
3387 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
3389 tree stmt
= bsi_stmt (bsi
);
3391 if (TREE_CODE (stmt
) != LABEL_EXPR
)
3393 if (LABEL_EXPR_LABEL (stmt
) == label
)
3400 /* Callback for walk_tree, check that all elements with address taken are
3401 properly noticed as such. The DATA is an int* that is 1 if TP was seen
3402 inside a PHI node. */
3405 verify_expr (tree
*tp
, int *walk_subtrees
, void *data ATTRIBUTE_UNUSED
)
3408 bool in_phi
= (data
!= NULL
);
3413 /* Check operand N for being valid GIMPLE and give error MSG if not.
3414 We check for constants explicitly since they are not considered
3415 gimple invariants if they overflowed. */
3416 #define CHECK_OP(N, MSG) \
3417 do { if (!CONSTANT_CLASS_P (TREE_OPERAND (t, N)) \
3418 && !is_gimple_val (TREE_OPERAND (t, N))) \
3419 { error (MSG); return TREE_OPERAND (t, N); }} while (0)
3421 switch (TREE_CODE (t
))
3424 if (SSA_NAME_IN_FREE_LIST (t
))
3426 error ("SSA name in freelist but still referenced");
3432 x
= TREE_OPERAND (t
, 0);
3433 if (TREE_CODE (x
) == BIT_FIELD_REF
3434 && is_gimple_reg (TREE_OPERAND (x
, 0)))
3436 error ("GIMPLE register modified with BIT_FIELD_REF");
3442 /* ??? tree-ssa-alias.c may have overlooked dead PHI nodes, missing
3443 dead PHIs that take the address of something. But if the PHI
3444 result is dead, the fact that it takes the address of anything
3445 is irrelevant. Because we can not tell from here if a PHI result
3446 is dead, we just skip this check for PHIs altogether. This means
3447 we may be missing "valid" checks, but what can you do?
3448 This was PR19217. */
3452 /* Skip any references (they will be checked when we recurse down the
3453 tree) and ensure that any variable used as a prefix is marked
3455 for (x
= TREE_OPERAND (t
, 0);
3456 handled_component_p (x
);
3457 x
= TREE_OPERAND (x
, 0))
3460 if (TREE_CODE (x
) != VAR_DECL
&& TREE_CODE (x
) != PARM_DECL
)
3462 if (!TREE_ADDRESSABLE (x
))
3464 error ("address taken, but ADDRESSABLE bit not set");
3470 x
= COND_EXPR_COND (t
);
3471 if (TREE_CODE (TREE_TYPE (x
)) != BOOLEAN_TYPE
)
3473 error ("non-boolean used in condition");
3480 case FIX_TRUNC_EXPR
:
3482 case FIX_FLOOR_EXPR
:
3483 case FIX_ROUND_EXPR
:
3488 case NON_LVALUE_EXPR
:
3489 case TRUTH_NOT_EXPR
:
3490 CHECK_OP (0, "Invalid operand to unary operator");
3497 case ARRAY_RANGE_REF
:
3499 case VIEW_CONVERT_EXPR
:
3500 /* We have a nest of references. Verify that each of the operands
3501 that determine where to reference is either a constant or a variable,
3502 verify that the base is valid, and then show we've already checked
3504 while (handled_component_p (t
))
3506 if (TREE_CODE (t
) == COMPONENT_REF
&& TREE_OPERAND (t
, 2))
3507 CHECK_OP (2, "Invalid COMPONENT_REF offset operator");
3508 else if (TREE_CODE (t
) == ARRAY_REF
3509 || TREE_CODE (t
) == ARRAY_RANGE_REF
)
3511 CHECK_OP (1, "Invalid array index.");
3512 if (TREE_OPERAND (t
, 2))
3513 CHECK_OP (2, "Invalid array lower bound.");
3514 if (TREE_OPERAND (t
, 3))
3515 CHECK_OP (3, "Invalid array stride.");
3517 else if (TREE_CODE (t
) == BIT_FIELD_REF
)
3519 CHECK_OP (1, "Invalid operand to BIT_FIELD_REF");
3520 CHECK_OP (2, "Invalid operand to BIT_FIELD_REF");
3523 t
= TREE_OPERAND (t
, 0);
3526 if (!CONSTANT_CLASS_P (t
) && !is_gimple_lvalue (t
))
3528 error ("Invalid reference prefix.");
3540 case UNORDERED_EXPR
:
3551 case TRUNC_DIV_EXPR
:
3553 case FLOOR_DIV_EXPR
:
3554 case ROUND_DIV_EXPR
:
3555 case TRUNC_MOD_EXPR
:
3557 case FLOOR_MOD_EXPR
:
3558 case ROUND_MOD_EXPR
:
3560 case EXACT_DIV_EXPR
:
3570 CHECK_OP (0, "Invalid operand to binary operator");
3571 CHECK_OP (1, "Invalid operand to binary operator");
3583 /* Verify STMT, return true if STMT is not in GIMPLE form.
3584 TODO: Implement type checking. */
3587 verify_stmt (tree stmt
, bool last_in_block
)
3591 if (!is_gimple_stmt (stmt
))
3593 error ("Is not a valid GIMPLE statement.");
3597 addr
= walk_tree (&stmt
, verify_expr
, NULL
, NULL
);
3600 debug_generic_stmt (addr
);
3604 /* If the statement is marked as part of an EH region, then it is
3605 expected that the statement could throw. Verify that when we
3606 have optimizations that simplify statements such that we prove
3607 that they cannot throw, that we update other data structures
3609 if (lookup_stmt_eh_region (stmt
) >= 0)
3611 if (!tree_could_throw_p (stmt
))
3613 error ("Statement marked for throw, but doesn%'t.");
3616 if (!last_in_block
&& tree_can_throw_internal (stmt
))
3618 error ("Statement marked for throw in middle of block.");
3626 debug_generic_stmt (stmt
);
3631 /* Return true when the T can be shared. */
3634 tree_node_can_be_shared (tree t
)
3636 if (IS_TYPE_OR_DECL_P (t
)
3637 /* We check for constants explicitly since they are not considered
3638 gimple invariants if they overflowed. */
3639 || CONSTANT_CLASS_P (t
)
3640 || is_gimple_min_invariant (t
)
3641 || TREE_CODE (t
) == SSA_NAME
3642 || t
== error_mark_node
)
3645 if (TREE_CODE (t
) == CASE_LABEL_EXPR
)
3648 while (((TREE_CODE (t
) == ARRAY_REF
|| TREE_CODE (t
) == ARRAY_RANGE_REF
)
3649 /* We check for constants explicitly since they are not considered
3650 gimple invariants if they overflowed. */
3651 && (CONSTANT_CLASS_P (TREE_OPERAND (t
, 1))
3652 || is_gimple_min_invariant (TREE_OPERAND (t
, 1))))
3653 || (TREE_CODE (t
) == COMPONENT_REF
3654 || TREE_CODE (t
) == REALPART_EXPR
3655 || TREE_CODE (t
) == IMAGPART_EXPR
))
3656 t
= TREE_OPERAND (t
, 0);
3665 /* Called via walk_trees. Verify tree sharing. */
3668 verify_node_sharing (tree
* tp
, int *walk_subtrees
, void *data
)
3670 htab_t htab
= (htab_t
) data
;
3673 if (tree_node_can_be_shared (*tp
))
3675 *walk_subtrees
= false;
3679 slot
= htab_find_slot (htab
, *tp
, INSERT
);
3688 /* Verify the GIMPLE statement chain. */
3694 block_stmt_iterator bsi
;
3699 timevar_push (TV_TREE_STMT_VERIFY
);
3700 htab
= htab_create (37, htab_hash_pointer
, htab_eq_pointer
, NULL
);
3707 for (phi
= phi_nodes (bb
); phi
; phi
= PHI_CHAIN (phi
))
3709 int phi_num_args
= PHI_NUM_ARGS (phi
);
3711 if (bb_for_stmt (phi
) != bb
)
3713 error ("bb_for_stmt (phi) is set to a wrong basic block\n");
3717 for (i
= 0; i
< phi_num_args
; i
++)
3719 tree t
= PHI_ARG_DEF (phi
, i
);
3722 /* Addressable variables do have SSA_NAMEs but they
3723 are not considered gimple values. */
3724 if (TREE_CODE (t
) != SSA_NAME
3725 && TREE_CODE (t
) != FUNCTION_DECL
3726 && !is_gimple_val (t
))
3728 error ("PHI def is not a GIMPLE value");
3729 debug_generic_stmt (phi
);
3730 debug_generic_stmt (t
);
3734 addr
= walk_tree (&t
, verify_expr
, (void *) 1, NULL
);
3737 debug_generic_stmt (addr
);
3741 addr
= walk_tree (&t
, verify_node_sharing
, htab
, NULL
);
3744 error ("Incorrect sharing of tree nodes");
3745 debug_generic_stmt (phi
);
3746 debug_generic_stmt (addr
);
3752 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); )
3754 tree stmt
= bsi_stmt (bsi
);
3756 if (bb_for_stmt (stmt
) != bb
)
3758 error ("bb_for_stmt (stmt) is set to a wrong basic block\n");
3763 err
|= verify_stmt (stmt
, bsi_end_p (bsi
));
3764 addr
= walk_tree (&stmt
, verify_node_sharing
, htab
, NULL
);
3767 error ("Incorrect sharing of tree nodes");
3768 debug_generic_stmt (stmt
);
3769 debug_generic_stmt (addr
);
3776 internal_error ("verify_stmts failed.");
3779 timevar_pop (TV_TREE_STMT_VERIFY
);
3783 /* Verifies that the flow information is OK. */
3786 tree_verify_flow_info (void)
3790 block_stmt_iterator bsi
;
3795 if (ENTRY_BLOCK_PTR
->stmt_list
)
3797 error ("ENTRY_BLOCK has a statement list associated with it\n");
3801 if (EXIT_BLOCK_PTR
->stmt_list
)
3803 error ("EXIT_BLOCK has a statement list associated with it\n");
3807 FOR_EACH_EDGE (e
, ei
, EXIT_BLOCK_PTR
->preds
)
3808 if (e
->flags
& EDGE_FALLTHRU
)
3810 error ("Fallthru to exit from bb %d\n", e
->src
->index
);
3816 bool found_ctrl_stmt
= false;
3820 /* Skip labels on the start of basic block. */
3821 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
3823 tree prev_stmt
= stmt
;
3825 stmt
= bsi_stmt (bsi
);
3827 if (TREE_CODE (stmt
) != LABEL_EXPR
)
3830 if (prev_stmt
&& DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt
)))
3832 error ("Nonlocal label %s is not first "
3833 "in a sequence of labels in bb %d",
3834 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt
))),
3839 if (label_to_block (LABEL_EXPR_LABEL (stmt
)) != bb
)
3841 error ("Label %s to block does not match in bb %d\n",
3842 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt
))),
3847 if (decl_function_context (LABEL_EXPR_LABEL (stmt
))
3848 != current_function_decl
)
3850 error ("Label %s has incorrect context in bb %d\n",
3851 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt
))),
3857 /* Verify that body of basic block BB is free of control flow. */
3858 for (; !bsi_end_p (bsi
); bsi_next (&bsi
))
3860 tree stmt
= bsi_stmt (bsi
);
3862 if (found_ctrl_stmt
)
3864 error ("Control flow in the middle of basic block %d\n",
3869 if (stmt_ends_bb_p (stmt
))
3870 found_ctrl_stmt
= true;
3872 if (TREE_CODE (stmt
) == LABEL_EXPR
)
3874 error ("Label %s in the middle of basic block %d\n",
3875 IDENTIFIER_POINTER (DECL_NAME (stmt
)),
3880 bsi
= bsi_last (bb
);
3881 if (bsi_end_p (bsi
))
3884 stmt
= bsi_stmt (bsi
);
3886 if (is_ctrl_stmt (stmt
))
3888 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
3889 if (e
->flags
& EDGE_FALLTHRU
)
3891 error ("Fallthru edge after a control statement in bb %d \n",
3897 switch (TREE_CODE (stmt
))
3903 if (TREE_CODE (COND_EXPR_THEN (stmt
)) != GOTO_EXPR
3904 || TREE_CODE (COND_EXPR_ELSE (stmt
)) != GOTO_EXPR
)
3906 error ("Structured COND_EXPR at the end of bb %d\n", bb
->index
);
3910 extract_true_false_edges_from_block (bb
, &true_edge
, &false_edge
);
3912 if (!true_edge
|| !false_edge
3913 || !(true_edge
->flags
& EDGE_TRUE_VALUE
)
3914 || !(false_edge
->flags
& EDGE_FALSE_VALUE
)
3915 || (true_edge
->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
))
3916 || (false_edge
->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
))
3917 || EDGE_COUNT (bb
->succs
) >= 3)
3919 error ("Wrong outgoing edge flags at end of bb %d\n",
3924 if (!has_label_p (true_edge
->dest
,
3925 GOTO_DESTINATION (COND_EXPR_THEN (stmt
))))
3927 error ("%<then%> label does not match edge at end of bb %d\n",
3932 if (!has_label_p (false_edge
->dest
,
3933 GOTO_DESTINATION (COND_EXPR_ELSE (stmt
))))
3935 error ("%<else%> label does not match edge at end of bb %d\n",
3943 if (simple_goto_p (stmt
))
3945 error ("Explicit goto at end of bb %d\n", bb
->index
);
3950 /* FIXME. We should double check that the labels in the
3951 destination blocks have their address taken. */
3952 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
3953 if ((e
->flags
& (EDGE_FALLTHRU
| EDGE_TRUE_VALUE
3954 | EDGE_FALSE_VALUE
))
3955 || !(e
->flags
& EDGE_ABNORMAL
))
3957 error ("Wrong outgoing edge flags at end of bb %d\n",
3965 if (!single_succ_p (bb
)
3966 || (single_succ_edge (bb
)->flags
3967 & (EDGE_FALLTHRU
| EDGE_ABNORMAL
3968 | EDGE_TRUE_VALUE
| EDGE_FALSE_VALUE
)))
3970 error ("Wrong outgoing edge flags at end of bb %d\n", bb
->index
);
3973 if (single_succ (bb
) != EXIT_BLOCK_PTR
)
3975 error ("Return edge does not point to exit in bb %d\n",
3988 vec
= SWITCH_LABELS (stmt
);
3989 n
= TREE_VEC_LENGTH (vec
);
3991 /* Mark all the destination basic blocks. */
3992 for (i
= 0; i
< n
; ++i
)
3994 tree lab
= CASE_LABEL (TREE_VEC_ELT (vec
, i
));
3995 basic_block label_bb
= label_to_block (lab
);
3997 gcc_assert (!label_bb
->aux
|| label_bb
->aux
== (void *)1);
3998 label_bb
->aux
= (void *)1;
4001 /* Verify that the case labels are sorted. */
4002 prev
= TREE_VEC_ELT (vec
, 0);
4003 for (i
= 1; i
< n
- 1; ++i
)
4005 tree c
= TREE_VEC_ELT (vec
, i
);
4008 error ("Found default case not at end of case vector");
4012 if (! tree_int_cst_lt (CASE_LOW (prev
), CASE_LOW (c
)))
4014 error ("Case labels not sorted:\n ");
4015 print_generic_expr (stderr
, prev
, 0);
4016 fprintf (stderr
," is greater than ");
4017 print_generic_expr (stderr
, c
, 0);
4018 fprintf (stderr
," but comes before it.\n");
4023 if (CASE_LOW (TREE_VEC_ELT (vec
, n
- 1)))
4025 error ("No default case found at end of case vector");
4029 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
4033 error ("Extra outgoing edge %d->%d\n",
4034 bb
->index
, e
->dest
->index
);
4037 e
->dest
->aux
= (void *)2;
4038 if ((e
->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
4039 | EDGE_TRUE_VALUE
| EDGE_FALSE_VALUE
)))
4041 error ("Wrong outgoing edge flags at end of bb %d\n",
4047 /* Check that we have all of them. */
4048 for (i
= 0; i
< n
; ++i
)
4050 tree lab
= CASE_LABEL (TREE_VEC_ELT (vec
, i
));
4051 basic_block label_bb
= label_to_block (lab
);
4053 if (label_bb
->aux
!= (void *)2)
4055 error ("Missing edge %i->%i",
4056 bb
->index
, label_bb
->index
);
4061 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
4062 e
->dest
->aux
= (void *)0;
4069 if (dom_computed
[CDI_DOMINATORS
] >= DOM_NO_FAST_QUERY
)
4070 verify_dominators (CDI_DOMINATORS
);
4076 /* Updates phi nodes after creating a forwarder block joined
4077 by edge FALLTHRU. */
4080 tree_make_forwarder_block (edge fallthru
)
4084 basic_block dummy
, bb
;
4085 tree phi
, new_phi
, var
;
4087 dummy
= fallthru
->src
;
4088 bb
= fallthru
->dest
;
4090 if (single_pred_p (bb
))
4093 /* If we redirected a branch we must create new phi nodes at the
4095 for (phi
= phi_nodes (dummy
); phi
; phi
= PHI_CHAIN (phi
))
4097 var
= PHI_RESULT (phi
);
4098 new_phi
= create_phi_node (var
, bb
);
4099 SSA_NAME_DEF_STMT (var
) = new_phi
;
4100 SET_PHI_RESULT (phi
, make_ssa_name (SSA_NAME_VAR (var
), phi
));
4101 add_phi_arg (new_phi
, PHI_RESULT (phi
), fallthru
);
4104 /* Ensure that the PHI node chain is in the same order. */
4105 set_phi_nodes (bb
, phi_reverse (phi_nodes (bb
)));
4107 /* Add the arguments we have stored on edges. */
4108 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
4113 flush_pending_stmts (e
);
4118 /* Return true if basic block BB does nothing except pass control
4119 flow to another block and that we can safely insert a label at
4120 the start of the successor block.
4122 As a precondition, we require that BB be not equal to
4126 tree_forwarder_block_p (basic_block bb
, bool phi_wanted
)
4128 block_stmt_iterator bsi
;
4130 /* BB must have a single outgoing edge. */
4131 if (single_succ_p (bb
) != 1
4132 /* If PHI_WANTED is false, BB must not have any PHI nodes.
4133 Otherwise, BB must have PHI nodes. */
4134 || (phi_nodes (bb
) != NULL_TREE
) != phi_wanted
4135 /* BB may not be a predecessor of EXIT_BLOCK_PTR. */
4136 || single_succ (bb
) == EXIT_BLOCK_PTR
4137 /* Nor should this be an infinite loop. */
4138 || single_succ (bb
) == bb
4139 /* BB may not have an abnormal outgoing edge. */
4140 || (single_succ_edge (bb
)->flags
& EDGE_ABNORMAL
))
4144 gcc_assert (bb
!= ENTRY_BLOCK_PTR
);
4147 /* Now walk through the statements backward. We can ignore labels,
4148 anything else means this is not a forwarder block. */
4149 for (bsi
= bsi_last (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
4151 tree stmt
= bsi_stmt (bsi
);
4153 switch (TREE_CODE (stmt
))
4156 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt
)))
4165 if (find_edge (ENTRY_BLOCK_PTR
, bb
))
4171 /* Protect loop latches, headers and preheaders. */
4172 if (bb
->loop_father
->header
== bb
)
4174 dest
= EDGE_SUCC (bb
, 0)->dest
;
4176 if (dest
->loop_father
->header
== dest
)
4183 /* Return true if BB has at least one abnormal incoming edge. */
4186 has_abnormal_incoming_edge_p (basic_block bb
)
4191 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
4192 if (e
->flags
& EDGE_ABNORMAL
)
4198 /* Removes forwarder block BB. Returns false if this failed. If a new
4199 forwarder block is created due to redirection of edges, it is
4200 stored to worklist. */
4203 remove_forwarder_block (basic_block bb
, basic_block
**worklist
)
4205 edge succ
= single_succ_edge (bb
), e
, s
;
4206 basic_block dest
= succ
->dest
;
4210 block_stmt_iterator bsi
, bsi_to
;
4211 bool seen_abnormal_edge
= false;
4213 /* We check for infinite loops already in tree_forwarder_block_p.
4214 However it may happen that the infinite loop is created
4215 afterwards due to removal of forwarders. */
4219 /* If the destination block consists of a nonlocal label, do not merge
4221 label
= first_stmt (dest
);
4223 && TREE_CODE (label
) == LABEL_EXPR
4224 && DECL_NONLOCAL (LABEL_EXPR_LABEL (label
)))
4227 /* If there is an abnormal edge to basic block BB, but not into
4228 dest, problems might occur during removal of the phi node at out
4229 of ssa due to overlapping live ranges of registers.
4231 If there is an abnormal edge in DEST, the problems would occur
4232 anyway since cleanup_dead_labels would then merge the labels for
4233 two different eh regions, and rest of exception handling code
4236 So if there is an abnormal edge to BB, proceed only if there is
4237 no abnormal edge to DEST and there are no phi nodes in DEST. */
4238 if (has_abnormal_incoming_edge_p (bb
))
4240 seen_abnormal_edge
= true;
4242 if (has_abnormal_incoming_edge_p (dest
)
4243 || phi_nodes (dest
) != NULL_TREE
)
4247 /* If there are phi nodes in DEST, and some of the blocks that are
4248 predecessors of BB are also predecessors of DEST, check that the
4249 phi node arguments match. */
4250 if (phi_nodes (dest
))
4252 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
4254 s
= find_edge (e
->src
, dest
);
4258 if (!phi_alternatives_equal (dest
, succ
, s
))
4263 /* Redirect the edges. */
4264 for (ei
= ei_start (bb
->preds
); (e
= ei_safe_edge (ei
)); )
4266 if (e
->flags
& EDGE_ABNORMAL
)
4268 /* If there is an abnormal edge, redirect it anyway, and
4269 move the labels to the new block to make it legal. */
4270 s
= redirect_edge_succ_nodup (e
, dest
);
4273 s
= redirect_edge_and_branch (e
, dest
);
4277 /* Create arguments for the phi nodes, since the edge was not
4279 for (phi
= phi_nodes (dest
); phi
; phi
= PHI_CHAIN (phi
))
4280 add_phi_arg (phi
, PHI_ARG_DEF (phi
, succ
->dest_idx
), s
);
4284 /* The source basic block might become a forwarder. We know
4285 that it was not a forwarder before, since it used to have
4286 at least two outgoing edges, so we may just add it to
4288 if (tree_forwarder_block_p (s
->src
, false))
4289 *(*worklist
)++ = s
->src
;
4293 if (seen_abnormal_edge
)
4295 /* Move the labels to the new block, so that the redirection of
4296 the abnormal edges works. */
4298 bsi_to
= bsi_start (dest
);
4299 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); )
4301 label
= bsi_stmt (bsi
);
4302 gcc_assert (TREE_CODE (label
) == LABEL_EXPR
);
4304 bsi_insert_before (&bsi_to
, label
, BSI_CONTINUE_LINKING
);
4308 /* Update the dominators. */
4309 if (dom_info_available_p (CDI_DOMINATORS
))
4311 basic_block dom
, dombb
, domdest
;
4313 dombb
= get_immediate_dominator (CDI_DOMINATORS
, bb
);
4314 domdest
= get_immediate_dominator (CDI_DOMINATORS
, dest
);
4317 /* Shortcut to avoid calling (relatively expensive)
4318 nearest_common_dominator unless necessary. */
4322 dom
= nearest_common_dominator (CDI_DOMINATORS
, domdest
, dombb
);
4324 set_immediate_dominator (CDI_DOMINATORS
, dest
, dom
);
4327 /* And kill the forwarder block. */
4328 delete_basic_block (bb
);
4333 /* Removes forwarder blocks. */
4336 cleanup_forwarder_blocks (void)
4339 bool changed
= false;
4340 basic_block
*worklist
= xmalloc (sizeof (basic_block
) * n_basic_blocks
);
4341 basic_block
*current
= worklist
;
4345 if (tree_forwarder_block_p (bb
, false))
4349 while (current
!= worklist
)
4352 changed
|= remove_forwarder_block (bb
, ¤t
);
4359 /* Merge the PHI nodes at BB into those at BB's sole successor. */
4362 remove_forwarder_block_with_phi (basic_block bb
)
4364 edge succ
= single_succ_edge (bb
);
4365 basic_block dest
= succ
->dest
;
4367 basic_block dombb
, domdest
, dom
;
4369 /* We check for infinite loops already in tree_forwarder_block_p.
4370 However it may happen that the infinite loop is created
4371 afterwards due to removal of forwarders. */
4375 /* If the destination block consists of a nonlocal label, do not
4377 label
= first_stmt (dest
);
4379 && TREE_CODE (label
) == LABEL_EXPR
4380 && DECL_NONLOCAL (LABEL_EXPR_LABEL (label
)))
4383 /* Redirect each incoming edge to BB to DEST. */
4384 while (EDGE_COUNT (bb
->preds
) > 0)
4386 edge e
= EDGE_PRED (bb
, 0), s
;
4389 s
= find_edge (e
->src
, dest
);
4392 /* We already have an edge S from E->src to DEST. If S and
4393 E->dest's sole successor edge have the same PHI arguments
4394 at DEST, redirect S to DEST. */
4395 if (phi_alternatives_equal (dest
, s
, succ
))
4397 e
= redirect_edge_and_branch (e
, dest
);
4398 PENDING_STMT (e
) = NULL_TREE
;
4402 /* PHI arguments are different. Create a forwarder block by
4403 splitting E so that we can merge PHI arguments on E to
4405 e
= single_succ_edge (split_edge (e
));
4408 s
= redirect_edge_and_branch (e
, dest
);
4410 /* redirect_edge_and_branch must not create a new edge. */
4411 gcc_assert (s
== e
);
4413 /* Add to the PHI nodes at DEST each PHI argument removed at the
4414 destination of E. */
4415 for (phi
= phi_nodes (dest
); phi
; phi
= PHI_CHAIN (phi
))
4417 tree def
= PHI_ARG_DEF (phi
, succ
->dest_idx
);
4419 if (TREE_CODE (def
) == SSA_NAME
)
4423 /* If DEF is one of the results of PHI nodes removed during
4424 redirection, replace it with the PHI argument that used
4426 for (var
= PENDING_STMT (e
); var
; var
= TREE_CHAIN (var
))
4428 tree old_arg
= TREE_PURPOSE (var
);
4429 tree new_arg
= TREE_VALUE (var
);
4439 add_phi_arg (phi
, def
, s
);
4442 PENDING_STMT (e
) = NULL
;
4445 /* Update the dominators. */
4446 dombb
= get_immediate_dominator (CDI_DOMINATORS
, bb
);
4447 domdest
= get_immediate_dominator (CDI_DOMINATORS
, dest
);
4450 /* Shortcut to avoid calling (relatively expensive)
4451 nearest_common_dominator unless necessary. */
4455 dom
= nearest_common_dominator (CDI_DOMINATORS
, domdest
, dombb
);
4457 set_immediate_dominator (CDI_DOMINATORS
, dest
, dom
);
4459 /* Remove BB since all of BB's incoming edges have been redirected
4461 delete_basic_block (bb
);
4464 /* This pass merges PHI nodes if one feeds into another. For example,
4465 suppose we have the following:
4472 # tem_6 = PHI <tem_17(8), tem_23(7)>;
4475 # tem_3 = PHI <tem_6(9), tem_2(5)>;
4478 Then we merge the first PHI node into the second one like so:
4480 goto <bb 9> (<L10>);
4485 # tem_3 = PHI <tem_23(7), tem_2(5), tem_17(8)>;
4490 merge_phi_nodes (void)
4492 basic_block
*worklist
= xmalloc (sizeof (basic_block
) * n_basic_blocks
);
4493 basic_block
*current
= worklist
;
4496 calculate_dominance_info (CDI_DOMINATORS
);
4498 /* Find all PHI nodes that we may be able to merge. */
4503 /* Look for a forwarder block with PHI nodes. */
4504 if (!tree_forwarder_block_p (bb
, true))
4507 dest
= single_succ (bb
);
4509 /* We have to feed into another basic block with PHI
4511 if (!phi_nodes (dest
)
4512 /* We don't want to deal with a basic block with
4514 || has_abnormal_incoming_edge_p (bb
))
4517 if (!dominated_by_p (CDI_DOMINATORS
, dest
, bb
))
4519 /* If BB does not dominate DEST, then the PHI nodes at
4520 DEST must be the only users of the results of the PHI
4526 /* Now let's drain WORKLIST. */
4527 while (current
!= worklist
)
4530 remove_forwarder_block_with_phi (bb
);
4537 gate_merge_phi (void)
4542 struct tree_opt_pass pass_merge_phi
= {
4543 "mergephi", /* name */
4544 gate_merge_phi
, /* gate */
4545 merge_phi_nodes
, /* execute */
4548 0, /* static_pass_number */
4549 TV_TREE_MERGE_PHI
, /* tv_id */
4550 PROP_cfg
| PROP_ssa
, /* properties_required */
4551 0, /* properties_provided */
4552 0, /* properties_destroyed */
4553 0, /* todo_flags_start */
4554 TODO_dump_func
| TODO_ggc_collect
/* todo_flags_finish */
4559 /* Return a non-special label in the head of basic block BLOCK.
4560 Create one if it doesn't exist. */
4563 tree_block_label (basic_block bb
)
4565 block_stmt_iterator i
, s
= bsi_start (bb
);
4569 for (i
= s
; !bsi_end_p (i
); first
= false, bsi_next (&i
))
4571 stmt
= bsi_stmt (i
);
4572 if (TREE_CODE (stmt
) != LABEL_EXPR
)
4574 label
= LABEL_EXPR_LABEL (stmt
);
4575 if (!DECL_NONLOCAL (label
))
4578 bsi_move_before (&i
, &s
);
4583 label
= create_artificial_label ();
4584 stmt
= build1 (LABEL_EXPR
, void_type_node
, label
);
4585 bsi_insert_before (&s
, stmt
, BSI_NEW_STMT
);
4590 /* Attempt to perform edge redirection by replacing a possibly complex
4591 jump instruction by a goto or by removing the jump completely.
4592 This can apply only if all edges now point to the same block. The
4593 parameters and return values are equivalent to
4594 redirect_edge_and_branch. */
4597 tree_try_redirect_by_replacing_jump (edge e
, basic_block target
)
4599 basic_block src
= e
->src
;
4600 block_stmt_iterator b
;
4603 /* We can replace or remove a complex jump only when we have exactly
4605 if (EDGE_COUNT (src
->succs
) != 2
4606 /* Verify that all targets will be TARGET. Specifically, the
4607 edge that is not E must also go to TARGET. */
4608 || EDGE_SUCC (src
, EDGE_SUCC (src
, 0) == e
)->dest
!= target
)
4614 stmt
= bsi_stmt (b
);
4616 if (TREE_CODE (stmt
) == COND_EXPR
4617 || TREE_CODE (stmt
) == SWITCH_EXPR
)
4620 e
= ssa_redirect_edge (e
, target
);
4621 e
->flags
= EDGE_FALLTHRU
;
4629 /* Redirect E to DEST. Return NULL on failure. Otherwise, return the
4630 edge representing the redirected branch. */
4633 tree_redirect_edge_and_branch (edge e
, basic_block dest
)
4635 basic_block bb
= e
->src
;
4636 block_stmt_iterator bsi
;
4640 if (e
->flags
& (EDGE_ABNORMAL_CALL
| EDGE_EH
))
4643 if (e
->src
!= ENTRY_BLOCK_PTR
4644 && (ret
= tree_try_redirect_by_replacing_jump (e
, dest
)))
4647 if (e
->dest
== dest
)
4650 label
= tree_block_label (dest
);
4652 bsi
= bsi_last (bb
);
4653 stmt
= bsi_end_p (bsi
) ? NULL
: bsi_stmt (bsi
);
4655 switch (stmt
? TREE_CODE (stmt
) : ERROR_MARK
)
4658 stmt
= (e
->flags
& EDGE_TRUE_VALUE
4659 ? COND_EXPR_THEN (stmt
)
4660 : COND_EXPR_ELSE (stmt
));
4661 GOTO_DESTINATION (stmt
) = label
;
4665 /* No non-abnormal edges should lead from a non-simple goto, and
4666 simple ones should be represented implicitly. */
4671 tree cases
= get_cases_for_edge (e
, stmt
);
4673 /* If we have a list of cases associated with E, then use it
4674 as it's a lot faster than walking the entire case vector. */
4677 edge e2
= find_edge (e
->src
, dest
);
4684 CASE_LABEL (cases
) = label
;
4685 cases
= TREE_CHAIN (cases
);
4688 /* If there was already an edge in the CFG, then we need
4689 to move all the cases associated with E to E2. */
4692 tree cases2
= get_cases_for_edge (e2
, stmt
);
4694 TREE_CHAIN (last
) = TREE_CHAIN (cases2
);
4695 TREE_CHAIN (cases2
) = first
;
4700 tree vec
= SWITCH_LABELS (stmt
);
4701 size_t i
, n
= TREE_VEC_LENGTH (vec
);
4703 for (i
= 0; i
< n
; i
++)
4705 tree elt
= TREE_VEC_ELT (vec
, i
);
4707 if (label_to_block (CASE_LABEL (elt
)) == e
->dest
)
4708 CASE_LABEL (elt
) = label
;
4717 e
->flags
|= EDGE_FALLTHRU
;
4721 /* Otherwise it must be a fallthru edge, and we don't need to
4722 do anything besides redirecting it. */
4723 gcc_assert (e
->flags
& EDGE_FALLTHRU
);
4727 /* Update/insert PHI nodes as necessary. */
4729 /* Now update the edges in the CFG. */
4730 e
= ssa_redirect_edge (e
, dest
);
4736 /* Simple wrapper, as we can always redirect fallthru edges. */
4739 tree_redirect_edge_and_branch_force (edge e
, basic_block dest
)
4741 e
= tree_redirect_edge_and_branch (e
, dest
);
4748 /* Splits basic block BB after statement STMT (but at least after the
4749 labels). If STMT is NULL, BB is split just after the labels. */
4752 tree_split_block (basic_block bb
, void *stmt
)
4754 block_stmt_iterator bsi
, bsi_tgt
;
4760 new_bb
= create_empty_bb (bb
);
4762 /* Redirect the outgoing edges. */
4763 new_bb
->succs
= bb
->succs
;
4765 FOR_EACH_EDGE (e
, ei
, new_bb
->succs
)
4768 if (stmt
&& TREE_CODE ((tree
) stmt
) == LABEL_EXPR
)
4771 /* Move everything from BSI to the new basic block. */
4772 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
4774 act
= bsi_stmt (bsi
);
4775 if (TREE_CODE (act
) == LABEL_EXPR
)
4788 bsi_tgt
= bsi_start (new_bb
);
4789 while (!bsi_end_p (bsi
))
4791 act
= bsi_stmt (bsi
);
4793 bsi_insert_after (&bsi_tgt
, act
, BSI_NEW_STMT
);
4800 /* Moves basic block BB after block AFTER. */
4803 tree_move_block_after (basic_block bb
, basic_block after
)
4805 if (bb
->prev_bb
== after
)
4809 link_block (bb
, after
);
4815 /* Return true if basic_block can be duplicated. */
4818 tree_can_duplicate_bb_p (basic_block bb ATTRIBUTE_UNUSED
)
4823 /* Create a duplicate of the basic block BB. NOTE: This does not
4824 preserve SSA form. */
4827 tree_duplicate_bb (basic_block bb
)
4830 block_stmt_iterator bsi
, bsi_tgt
;
4832 ssa_op_iter op_iter
;
4834 new_bb
= create_empty_bb (EXIT_BLOCK_PTR
->prev_bb
);
4836 /* First copy the phi nodes. We do not copy phi node arguments here,
4837 since the edges are not ready yet. Keep the chain of phi nodes in
4838 the same order, so that we can add them later. */
4839 for (phi
= phi_nodes (bb
); phi
; phi
= PHI_CHAIN (phi
))
4841 mark_for_rewrite (PHI_RESULT (phi
));
4842 create_phi_node (PHI_RESULT (phi
), new_bb
);
4844 set_phi_nodes (new_bb
, phi_reverse (phi_nodes (new_bb
)));
4846 bsi_tgt
= bsi_start (new_bb
);
4847 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
4849 tree stmt
= bsi_stmt (bsi
);
4852 if (TREE_CODE (stmt
) == LABEL_EXPR
)
4855 /* Record the definitions. */
4856 get_stmt_operands (stmt
);
4858 FOR_EACH_SSA_TREE_OPERAND (val
, stmt
, op_iter
, SSA_OP_ALL_DEFS
)
4859 mark_for_rewrite (val
);
4861 copy
= unshare_expr (stmt
);
4863 /* Copy also the virtual operands. */
4864 get_stmt_ann (copy
);
4865 copy_virtual_operands (copy
, stmt
);
4867 bsi_insert_after (&bsi_tgt
, copy
, BSI_NEW_STMT
);
4873 /* Basic block BB_COPY was created by code duplication. Add phi node
4874 arguments for edges going out of BB_COPY. The blocks that were
4875 duplicated have rbi->duplicated set to one. */
4878 add_phi_args_after_copy_bb (basic_block bb_copy
)
4880 basic_block bb
, dest
;
4883 tree phi
, phi_copy
, phi_next
, def
;
4885 bb
= bb_copy
->rbi
->original
;
4887 FOR_EACH_EDGE (e_copy
, ei
, bb_copy
->succs
)
4889 if (!phi_nodes (e_copy
->dest
))
4892 if (e_copy
->dest
->rbi
->duplicated
)
4893 dest
= e_copy
->dest
->rbi
->original
;
4895 dest
= e_copy
->dest
;
4897 e
= find_edge (bb
, dest
);
4900 /* During loop unrolling the target of the latch edge is copied.
4901 In this case we are not looking for edge to dest, but to
4902 duplicated block whose original was dest. */
4903 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
4904 if (e
->dest
->rbi
->duplicated
4905 && e
->dest
->rbi
->original
== dest
)
4908 gcc_assert (e
!= NULL
);
4911 for (phi
= phi_nodes (e
->dest
), phi_copy
= phi_nodes (e_copy
->dest
);
4913 phi
= phi_next
, phi_copy
= PHI_CHAIN (phi_copy
))
4915 phi_next
= PHI_CHAIN (phi
);
4917 gcc_assert (PHI_RESULT (phi
) == PHI_RESULT (phi_copy
));
4918 def
= PHI_ARG_DEF_FROM_EDGE (phi
, e
);
4919 add_phi_arg (phi_copy
, def
, e_copy
);
4924 /* Blocks in REGION_COPY array of length N_REGION were created by
4925 duplication of basic blocks. Add phi node arguments for edges
4926 going from these blocks. */
4929 add_phi_args_after_copy (basic_block
*region_copy
, unsigned n_region
)
4933 for (i
= 0; i
< n_region
; i
++)
4934 region_copy
[i
]->rbi
->duplicated
= 1;
4936 for (i
= 0; i
< n_region
; i
++)
4937 add_phi_args_after_copy_bb (region_copy
[i
]);
4939 for (i
= 0; i
< n_region
; i
++)
4940 region_copy
[i
]->rbi
->duplicated
= 0;
4943 /* Maps the old ssa name FROM_NAME to TO_NAME. */
4945 struct ssa_name_map_entry
4951 /* Hash function for ssa_name_map_entry. */
4954 ssa_name_map_entry_hash (const void *entry
)
4956 const struct ssa_name_map_entry
*en
= entry
;
4957 return SSA_NAME_VERSION (en
->from_name
);
4960 /* Equality function for ssa_name_map_entry. */
4963 ssa_name_map_entry_eq (const void *in_table
, const void *ssa_name
)
4965 const struct ssa_name_map_entry
*en
= in_table
;
4967 return en
->from_name
== ssa_name
;
4970 /* Allocate duplicates of ssa names in list DEFINITIONS and store the mapping
4974 allocate_ssa_names (bitmap definitions
, htab_t
*map
)
4977 struct ssa_name_map_entry
*entry
;
4983 *map
= htab_create (10, ssa_name_map_entry_hash
,
4984 ssa_name_map_entry_eq
, free
);
4985 EXECUTE_IF_SET_IN_BITMAP (definitions
, 0, ver
, bi
)
4987 name
= ssa_name (ver
);
4988 slot
= htab_find_slot_with_hash (*map
, name
, SSA_NAME_VERSION (name
),
4994 entry
= xmalloc (sizeof (struct ssa_name_map_entry
));
4995 entry
->from_name
= name
;
4998 entry
->to_name
= duplicate_ssa_name (name
, SSA_NAME_DEF_STMT (name
));
5002 /* Rewrite the definition DEF in statement STMT to new ssa name as specified
5003 by the mapping MAP. */
5006 rewrite_to_new_ssa_names_def (def_operand_p def
, tree stmt
, htab_t map
)
5008 tree name
= DEF_FROM_PTR (def
);
5009 struct ssa_name_map_entry
*entry
;
5011 gcc_assert (TREE_CODE (name
) == SSA_NAME
);
5013 entry
= htab_find_with_hash (map
, name
, SSA_NAME_VERSION (name
));
5017 SET_DEF (def
, entry
->to_name
);
5018 SSA_NAME_DEF_STMT (entry
->to_name
) = stmt
;
5021 /* Rewrite the USE to new ssa name as specified by the mapping MAP. */
5024 rewrite_to_new_ssa_names_use (use_operand_p use
, htab_t map
)
5026 tree name
= USE_FROM_PTR (use
);
5027 struct ssa_name_map_entry
*entry
;
5029 if (TREE_CODE (name
) != SSA_NAME
)
5032 entry
= htab_find_with_hash (map
, name
, SSA_NAME_VERSION (name
));
5036 SET_USE (use
, entry
->to_name
);
5039 /* Rewrite the ssa names in basic block BB to new ones as specified by the
5043 rewrite_to_new_ssa_names_bb (basic_block bb
, htab_t map
)
5049 block_stmt_iterator bsi
;
5053 v_may_def_optype v_may_defs
;
5054 v_must_def_optype v_must_defs
;
5057 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
5058 if (e
->flags
& EDGE_ABNORMAL
)
5061 for (phi
= phi_nodes (bb
); phi
; phi
= PHI_CHAIN (phi
))
5063 rewrite_to_new_ssa_names_def (PHI_RESULT_PTR (phi
), phi
, map
);
5065 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (PHI_RESULT (phi
)) = 1;
5068 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
5070 stmt
= bsi_stmt (bsi
);
5071 get_stmt_operands (stmt
);
5072 ann
= stmt_ann (stmt
);
5074 uses
= USE_OPS (ann
);
5075 for (i
= 0; i
< NUM_USES (uses
); i
++)
5076 rewrite_to_new_ssa_names_use (USE_OP_PTR (uses
, i
), map
);
5078 defs
= DEF_OPS (ann
);
5079 for (i
= 0; i
< NUM_DEFS (defs
); i
++)
5080 rewrite_to_new_ssa_names_def (DEF_OP_PTR (defs
, i
), stmt
, map
);
5082 vuses
= VUSE_OPS (ann
);
5083 for (i
= 0; i
< NUM_VUSES (vuses
); i
++)
5084 rewrite_to_new_ssa_names_use (VUSE_OP_PTR (vuses
, i
), map
);
5086 v_may_defs
= V_MAY_DEF_OPS (ann
);
5087 for (i
= 0; i
< NUM_V_MAY_DEFS (v_may_defs
); i
++)
5089 rewrite_to_new_ssa_names_use
5090 (V_MAY_DEF_OP_PTR (v_may_defs
, i
), map
);
5091 rewrite_to_new_ssa_names_def
5092 (V_MAY_DEF_RESULT_PTR (v_may_defs
, i
), stmt
, map
);
5095 v_must_defs
= V_MUST_DEF_OPS (ann
);
5096 for (i
= 0; i
< NUM_V_MUST_DEFS (v_must_defs
); i
++)
5098 rewrite_to_new_ssa_names_def
5099 (V_MUST_DEF_RESULT_PTR (v_must_defs
, i
), stmt
, map
);
5100 rewrite_to_new_ssa_names_use
5101 (V_MUST_DEF_KILL_PTR (v_must_defs
, i
), map
);
5105 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
5106 for (phi
= phi_nodes (e
->dest
); phi
; phi
= PHI_CHAIN (phi
))
5108 rewrite_to_new_ssa_names_use
5109 (PHI_ARG_DEF_PTR_FROM_EDGE (phi
, e
), map
);
5111 if (e
->flags
& EDGE_ABNORMAL
)
5113 tree op
= PHI_ARG_DEF_FROM_EDGE (phi
, e
);
5114 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op
) = 1;
5119 /* Rewrite the ssa names in N_REGION blocks REGION to the new ones as specified
5120 by the mapping MAP. */
5123 rewrite_to_new_ssa_names (basic_block
*region
, unsigned n_region
, htab_t map
)
5127 for (r
= 0; r
< n_region
; r
++)
5128 rewrite_to_new_ssa_names_bb (region
[r
], map
);
5131 /* Duplicates a REGION (set of N_REGION basic blocks) with just a single
5132 important exit edge EXIT. By important we mean that no SSA name defined
5133 inside region is live over the other exit edges of the region. All entry
5134 edges to the region must go to ENTRY->dest. The edge ENTRY is redirected
5135 to the duplicate of the region. SSA form, dominance and loop information
5136 is updated. The new basic blocks are stored to REGION_COPY in the same
5137 order as they had in REGION, provided that REGION_COPY is not NULL.
5138 The function returns false if it is unable to copy the region,
5142 tree_duplicate_sese_region (edge entry
, edge exit
,
5143 basic_block
*region
, unsigned n_region
,
5144 basic_block
*region_copy
)
5146 unsigned i
, n_doms
, ver
;
5147 bool free_region_copy
= false, copying_header
= false;
5148 struct loop
*loop
= entry
->dest
->loop_father
;
5153 htab_t ssa_name_map
= NULL
;
5157 if (!can_copy_bbs_p (region
, n_region
))
5160 /* Some sanity checking. Note that we do not check for all possible
5161 missuses of the functions. I.e. if you ask to copy something weird,
5162 it will work, but the state of structures probably will not be
5165 for (i
= 0; i
< n_region
; i
++)
5167 /* We do not handle subloops, i.e. all the blocks must belong to the
5169 if (region
[i
]->loop_father
!= loop
)
5172 if (region
[i
] != entry
->dest
5173 && region
[i
] == loop
->header
)
5179 /* In case the function is used for loop header copying (which is the primary
5180 use), ensure that EXIT and its copy will be new latch and entry edges. */
5181 if (loop
->header
== entry
->dest
)
5183 copying_header
= true;
5184 loop
->copy
= loop
->outer
;
5186 if (!dominated_by_p (CDI_DOMINATORS
, loop
->latch
, exit
->src
))
5189 for (i
= 0; i
< n_region
; i
++)
5190 if (region
[i
] != exit
->src
5191 && dominated_by_p (CDI_DOMINATORS
, region
[i
], exit
->src
))
5197 region_copy
= xmalloc (sizeof (basic_block
) * n_region
);
5198 free_region_copy
= true;
5201 gcc_assert (!any_marked_for_rewrite_p ());
5203 /* Record blocks outside the region that are duplicated by something
5205 doms
= xmalloc (sizeof (basic_block
) * n_basic_blocks
);
5206 n_doms
= get_dominated_by_region (CDI_DOMINATORS
, region
, n_region
, doms
);
5208 copy_bbs (region
, n_region
, region_copy
, &exit
, 1, &exit_copy
, loop
);
5209 definitions
= marked_ssa_names ();
5213 loop
->header
= exit
->dest
;
5214 loop
->latch
= exit
->src
;
5217 /* Redirect the entry and add the phi node arguments. */
5218 redirected
= redirect_edge_and_branch (entry
, entry
->dest
->rbi
->copy
);
5219 gcc_assert (redirected
!= NULL
);
5220 flush_pending_stmts (entry
);
5222 /* Concerning updating of dominators: We must recount dominators
5223 for entry block and its copy. Anything that is outside of the region, but
5224 was dominated by something inside needs recounting as well. */
5225 set_immediate_dominator (CDI_DOMINATORS
, entry
->dest
, entry
->src
);
5226 doms
[n_doms
++] = entry
->dest
->rbi
->original
;
5227 iterate_fix_dominators (CDI_DOMINATORS
, doms
, n_doms
);
5230 /* Add the other phi node arguments. */
5231 add_phi_args_after_copy (region_copy
, n_region
);
5233 /* Add phi nodes for definitions at exit. TODO -- once we have immediate
5234 uses, it should be possible to emit phi nodes just for definitions that
5235 are used outside region. */
5236 EXECUTE_IF_SET_IN_BITMAP (definitions
, 0, ver
, bi
)
5238 tree name
= ssa_name (ver
);
5240 phi
= create_phi_node (name
, exit
->dest
);
5241 add_phi_arg (phi
, name
, exit
);
5242 add_phi_arg (phi
, name
, exit_copy
);
5244 SSA_NAME_DEF_STMT (name
) = phi
;
5247 /* And create new definitions inside region and its copy. TODO -- once we
5248 have immediate uses, it might be better to leave definitions in region
5249 unchanged, create new ssa names for phi nodes on exit, and rewrite
5250 the uses, to avoid changing the copied region. */
5251 allocate_ssa_names (definitions
, &ssa_name_map
);
5252 rewrite_to_new_ssa_names (region
, n_region
, ssa_name_map
);
5253 allocate_ssa_names (definitions
, &ssa_name_map
);
5254 rewrite_to_new_ssa_names (region_copy
, n_region
, ssa_name_map
);
5255 htab_delete (ssa_name_map
);
5257 if (free_region_copy
)
5260 unmark_all_for_rewrite ();
5261 BITMAP_FREE (definitions
);
5266 /* Dump FUNCTION_DECL FN to file FILE using FLAGS (see TDF_* in tree.h) */
5269 dump_function_to_file (tree fn
, FILE *file
, int flags
)
5271 tree arg
, vars
, var
;
5272 bool ignore_topmost_bind
= false, any_var
= false;
5276 fprintf (file
, "%s (", lang_hooks
.decl_printable_name (fn
, 2));
5278 arg
= DECL_ARGUMENTS (fn
);
5281 print_generic_expr (file
, arg
, dump_flags
);
5282 if (TREE_CHAIN (arg
))
5283 fprintf (file
, ", ");
5284 arg
= TREE_CHAIN (arg
);
5286 fprintf (file
, ")\n");
5288 if (flags
& TDF_RAW
)
5290 dump_node (fn
, TDF_SLIM
| flags
, file
);
5294 /* When GIMPLE is lowered, the variables are no longer available in
5295 BIND_EXPRs, so display them separately. */
5296 if (cfun
&& cfun
->unexpanded_var_list
)
5298 ignore_topmost_bind
= true;
5300 fprintf (file
, "{\n");
5301 for (vars
= cfun
->unexpanded_var_list
; vars
; vars
= TREE_CHAIN (vars
))
5303 var
= TREE_VALUE (vars
);
5305 print_generic_decl (file
, var
, flags
);
5306 fprintf (file
, "\n");
5312 if (basic_block_info
)
5314 /* Make a CFG based dump. */
5315 check_bb_profile (ENTRY_BLOCK_PTR
, file
);
5316 if (!ignore_topmost_bind
)
5317 fprintf (file
, "{\n");
5319 if (any_var
&& n_basic_blocks
)
5320 fprintf (file
, "\n");
5323 dump_generic_bb (file
, bb
, 2, flags
);
5325 fprintf (file
, "}\n");
5326 check_bb_profile (EXIT_BLOCK_PTR
, file
);
5332 /* Make a tree based dump. */
5333 chain
= DECL_SAVED_TREE (fn
);
5335 if (TREE_CODE (chain
) == BIND_EXPR
)
5337 if (ignore_topmost_bind
)
5339 chain
= BIND_EXPR_BODY (chain
);
5347 if (!ignore_topmost_bind
)
5348 fprintf (file
, "{\n");
5353 fprintf (file
, "\n");
5355 print_generic_stmt_indented (file
, chain
, flags
, indent
);
5356 if (ignore_topmost_bind
)
5357 fprintf (file
, "}\n");
5360 fprintf (file
, "\n\n");
5364 /* Pretty print of the loops intermediate representation. */
5365 static void print_loop (FILE *, struct loop
*, int);
5366 static void print_pred_bbs (FILE *, basic_block bb
);
5367 static void print_succ_bbs (FILE *, basic_block bb
);
5370 /* Print the predecessors indexes of edge E on FILE. */
5373 print_pred_bbs (FILE *file
, basic_block bb
)
5378 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
5379 fprintf (file
, "bb_%d", e
->src
->index
);
5383 /* Print the successors indexes of edge E on FILE. */
5386 print_succ_bbs (FILE *file
, basic_block bb
)
5391 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
5392 fprintf (file
, "bb_%d", e
->src
->index
);
5396 /* Pretty print LOOP on FILE, indented INDENT spaces. */
5399 print_loop (FILE *file
, struct loop
*loop
, int indent
)
5407 s_indent
= (char *) alloca ((size_t) indent
+ 1);
5408 memset ((void *) s_indent
, ' ', (size_t) indent
);
5409 s_indent
[indent
] = '\0';
5411 /* Print the loop's header. */
5412 fprintf (file
, "%sloop_%d\n", s_indent
, loop
->num
);
5414 /* Print the loop's body. */
5415 fprintf (file
, "%s{\n", s_indent
);
5417 if (bb
->loop_father
== loop
)
5419 /* Print the basic_block's header. */
5420 fprintf (file
, "%s bb_%d (preds = {", s_indent
, bb
->index
);
5421 print_pred_bbs (file
, bb
);
5422 fprintf (file
, "}, succs = {");
5423 print_succ_bbs (file
, bb
);
5424 fprintf (file
, "})\n");
5426 /* Print the basic_block's body. */
5427 fprintf (file
, "%s {\n", s_indent
);
5428 tree_dump_bb (bb
, file
, indent
+ 4);
5429 fprintf (file
, "%s }\n", s_indent
);
5432 print_loop (file
, loop
->inner
, indent
+ 2);
5433 fprintf (file
, "%s}\n", s_indent
);
5434 print_loop (file
, loop
->next
, indent
);
5438 /* Follow a CFG edge from the entry point of the program, and on entry
5439 of a loop, pretty print the loop structure on FILE. */
5442 print_loop_ir (FILE *file
)
5446 bb
= BASIC_BLOCK (0);
5447 if (bb
&& bb
->loop_father
)
5448 print_loop (file
, bb
->loop_father
, 0);
5452 /* Debugging loops structure at tree level. */
5455 debug_loop_ir (void)
5457 print_loop_ir (stderr
);
5461 /* Return true if BB ends with a call, possibly followed by some
5462 instructions that must stay with the call. Return false,
5466 tree_block_ends_with_call_p (basic_block bb
)
5468 block_stmt_iterator bsi
= bsi_last (bb
);
5469 return get_call_expr_in (bsi_stmt (bsi
)) != NULL
;
5473 /* Return true if BB ends with a conditional branch. Return false,
5477 tree_block_ends_with_condjump_p (basic_block bb
)
5479 tree stmt
= tsi_stmt (bsi_last (bb
).tsi
);
5480 return (TREE_CODE (stmt
) == COND_EXPR
);
5484 /* Return true if we need to add fake edge to exit at statement T.
5485 Helper function for tree_flow_call_edges_add. */
5488 need_fake_edge_p (tree t
)
5492 /* NORETURN and LONGJMP calls already have an edge to exit.
5493 CONST and PURE calls do not need one.
5494 We don't currently check for CONST and PURE here, although
5495 it would be a good idea, because those attributes are
5496 figured out from the RTL in mark_constant_function, and
5497 the counter incrementation code from -fprofile-arcs
5498 leads to different results from -fbranch-probabilities. */
5499 call
= get_call_expr_in (t
);
5501 && !(call_expr_flags (call
) & ECF_NORETURN
))
5504 if (TREE_CODE (t
) == ASM_EXPR
5505 && (ASM_VOLATILE_P (t
) || ASM_INPUT_P (t
)))
5512 /* Add fake edges to the function exit for any non constant and non
5513 noreturn calls, volatile inline assembly in the bitmap of blocks
5514 specified by BLOCKS or to the whole CFG if BLOCKS is zero. Return
5515 the number of blocks that were split.
5517 The goal is to expose cases in which entering a basic block does
5518 not imply that all subsequent instructions must be executed. */
5521 tree_flow_call_edges_add (sbitmap blocks
)
5524 int blocks_split
= 0;
5525 int last_bb
= last_basic_block
;
5526 bool check_last_block
= false;
5528 if (n_basic_blocks
== 0)
5532 check_last_block
= true;
5534 check_last_block
= TEST_BIT (blocks
, EXIT_BLOCK_PTR
->prev_bb
->index
);
5536 /* In the last basic block, before epilogue generation, there will be
5537 a fallthru edge to EXIT. Special care is required if the last insn
5538 of the last basic block is a call because make_edge folds duplicate
5539 edges, which would result in the fallthru edge also being marked
5540 fake, which would result in the fallthru edge being removed by
5541 remove_fake_edges, which would result in an invalid CFG.
5543 Moreover, we can't elide the outgoing fake edge, since the block
5544 profiler needs to take this into account in order to solve the minimal
5545 spanning tree in the case that the call doesn't return.
5547 Handle this by adding a dummy instruction in a new last basic block. */
5548 if (check_last_block
)
5550 basic_block bb
= EXIT_BLOCK_PTR
->prev_bb
;
5551 block_stmt_iterator bsi
= bsi_last (bb
);
5553 if (!bsi_end_p (bsi
))
5556 if (need_fake_edge_p (t
))
5560 e
= find_edge (bb
, EXIT_BLOCK_PTR
);
5563 bsi_insert_on_edge (e
, build_empty_stmt ());
5564 bsi_commit_edge_inserts ();
5569 /* Now add fake edges to the function exit for any non constant
5570 calls since there is no way that we can determine if they will
5572 for (i
= 0; i
< last_bb
; i
++)
5574 basic_block bb
= BASIC_BLOCK (i
);
5575 block_stmt_iterator bsi
;
5576 tree stmt
, last_stmt
;
5581 if (blocks
&& !TEST_BIT (blocks
, i
))
5584 bsi
= bsi_last (bb
);
5585 if (!bsi_end_p (bsi
))
5587 last_stmt
= bsi_stmt (bsi
);
5590 stmt
= bsi_stmt (bsi
);
5591 if (need_fake_edge_p (stmt
))
5594 /* The handling above of the final block before the
5595 epilogue should be enough to verify that there is
5596 no edge to the exit block in CFG already.
5597 Calling make_edge in such case would cause us to
5598 mark that edge as fake and remove it later. */
5599 #ifdef ENABLE_CHECKING
5600 if (stmt
== last_stmt
)
5602 e
= find_edge (bb
, EXIT_BLOCK_PTR
);
5603 gcc_assert (e
== NULL
);
5607 /* Note that the following may create a new basic block
5608 and renumber the existing basic blocks. */
5609 if (stmt
!= last_stmt
)
5611 e
= split_block (bb
, stmt
);
5615 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
5619 while (!bsi_end_p (bsi
));
5624 verify_flow_info ();
5626 return blocks_split
;
5630 tree_purge_dead_eh_edges (basic_block bb
)
5632 bool changed
= false;
5635 tree stmt
= last_stmt (bb
);
5637 if (stmt
&& tree_can_throw_internal (stmt
))
5640 for (ei
= ei_start (bb
->succs
); (e
= ei_safe_edge (ei
)); )
5642 if (e
->flags
& EDGE_EH
)
5651 /* Removal of dead EH edges might change dominators of not
5652 just immediate successors. E.g. when bb1 is changed so that
5653 it no longer can throw and bb1->bb3 and bb1->bb4 are dead
5654 eh edges purged by this function in:
5666 idom(bb5) must be recomputed. For now just free the dominance
5669 free_dominance_info (CDI_DOMINATORS
);
5675 tree_purge_all_dead_eh_edges (bitmap blocks
)
5677 bool changed
= false;
5681 EXECUTE_IF_SET_IN_BITMAP (blocks
, 0, i
, bi
)
5683 changed
|= tree_purge_dead_eh_edges (BASIC_BLOCK (i
));
5689 /* This function is called whenever a new edge is created or
5693 tree_execute_on_growing_pred (edge e
)
5695 basic_block bb
= e
->dest
;
5698 reserve_phi_args_for_new_edge (bb
);
5701 /* This function is called immediately before edge E is removed from
5702 the edge vector E->dest->preds. */
5705 tree_execute_on_shrinking_pred (edge e
)
5707 if (phi_nodes (e
->dest
))
5708 remove_phi_args (e
);
5711 /*---------------------------------------------------------------------------
5712 Helper functions for Loop versioning
5713 ---------------------------------------------------------------------------*/
5715 /* Adjust phi nodes for 'first' basic block. 'second' basic block is a copy
5716 of 'first'. Both of them are dominated by 'new_head' basic block. When
5717 'new_head' was created by 'second's incoming edge it received phi arguments
5718 on the edge by split_edge(). Later, additional edge 'e' was created to
5719 connect 'new_head' and 'first'. Now this routine adds phi args on this
5720 additional edge 'e' that new_head to second edge received as part of edge
5725 tree_lv_adjust_loop_header_phi (basic_block first
, basic_block second
,
5726 basic_block new_head
, edge e
)
5730 /* Browse all 'second' basic block phi nodes and add phi args to
5731 edge 'e' for 'first' head. PHI args are always in correct order. */
5733 for (phi2
= phi_nodes (second
), phi1
= phi_nodes (first
);
5735 phi2
= PHI_CHAIN (phi2
), phi1
= PHI_CHAIN (phi1
))
5737 edge e2
= find_edge (new_head
, second
);
5741 tree def
= PHI_ARG_DEF (phi2
, e2
->dest_idx
);
5742 add_phi_arg (phi1
, def
, e
);
5747 /* Adds a if else statement to COND_BB with condition COND_EXPR.
5748 SECOND_HEAD is the destination of the THEN and FIRST_HEAD is
5749 the destination of the ELSE part. */
5751 tree_lv_add_condition_to_bb (basic_block first_head
, basic_block second_head
,
5752 basic_block cond_bb
, void *cond_e
)
5754 block_stmt_iterator bsi
;
5755 tree goto1
= NULL_TREE
;
5756 tree goto2
= NULL_TREE
;
5757 tree new_cond_expr
= NULL_TREE
;
5758 tree cond_expr
= (tree
) cond_e
;
5761 /* Build new conditional expr */
5762 goto1
= build1 (GOTO_EXPR
, void_type_node
, tree_block_label (first_head
));
5763 goto2
= build1 (GOTO_EXPR
, void_type_node
, tree_block_label (second_head
));
5764 new_cond_expr
= build3 (COND_EXPR
, void_type_node
, cond_expr
, goto1
, goto2
);
5766 /* Add new cond in cond_bb. */
5767 bsi
= bsi_start (cond_bb
);
5768 bsi_insert_after (&bsi
, new_cond_expr
, BSI_NEW_STMT
);
5769 /* Adjust edges appropriately to connect new head with first head
5770 as well as second head. */
5771 e0
= single_succ_edge (cond_bb
);
5772 e0
->flags
&= ~EDGE_FALLTHRU
;
5773 e0
->flags
|= EDGE_FALSE_VALUE
;
5776 struct cfg_hooks tree_cfg_hooks
= {
5778 tree_verify_flow_info
,
5779 tree_dump_bb
, /* dump_bb */
5780 create_bb
, /* create_basic_block */
5781 tree_redirect_edge_and_branch
,/* redirect_edge_and_branch */
5782 tree_redirect_edge_and_branch_force
,/* redirect_edge_and_branch_force */
5783 remove_bb
, /* delete_basic_block */
5784 tree_split_block
, /* split_block */
5785 tree_move_block_after
, /* move_block_after */
5786 tree_can_merge_blocks_p
, /* can_merge_blocks_p */
5787 tree_merge_blocks
, /* merge_blocks */
5788 tree_predict_edge
, /* predict_edge */
5789 tree_predicted_by_p
, /* predicted_by_p */
5790 tree_can_duplicate_bb_p
, /* can_duplicate_block_p */
5791 tree_duplicate_bb
, /* duplicate_block */
5792 tree_split_edge
, /* split_edge */
5793 tree_make_forwarder_block
, /* make_forward_block */
5794 NULL
, /* tidy_fallthru_edge */
5795 tree_block_ends_with_call_p
, /* block_ends_with_call_p */
5796 tree_block_ends_with_condjump_p
, /* block_ends_with_condjump_p */
5797 tree_flow_call_edges_add
, /* flow_call_edges_add */
5798 tree_execute_on_growing_pred
, /* execute_on_growing_pred */
5799 tree_execute_on_shrinking_pred
, /* execute_on_shrinking_pred */
5800 tree_duplicate_loop_to_header_edge
, /* duplicate loop for trees */
5801 tree_lv_add_condition_to_bb
, /* lv_add_condition_to_bb */
5802 tree_lv_adjust_loop_header_phi
, /* lv_adjust_loop_header_phi*/
5803 extract_true_false_edges_from_block
, /* extract_cond_bb_edges */
5804 flush_pending_stmts
/* flush_pending_stmts */
5808 /* Split all critical edges. */
5811 split_critical_edges (void)
5817 /* split_edge can redirect edges out of SWITCH_EXPRs, which can get
5818 expensive. So we want to enable recording of edge to CASE_LABEL_EXPR
5819 mappings around the calls to split_edge. */
5820 start_recording_case_labels ();
5823 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
5824 if (EDGE_CRITICAL_P (e
) && !(e
->flags
& EDGE_ABNORMAL
))
5829 end_recording_case_labels ();
5832 struct tree_opt_pass pass_split_crit_edges
=
5834 "crited", /* name */
5836 split_critical_edges
, /* execute */
5839 0, /* static_pass_number */
5840 TV_TREE_SPLIT_EDGES
, /* tv_id */
5841 PROP_cfg
, /* properties required */
5842 PROP_no_crit_edges
, /* properties_provided */
5843 0, /* properties_destroyed */
5844 0, /* todo_flags_start */
5845 TODO_dump_func
, /* todo_flags_finish */
5850 /* Return EXP if it is a valid GIMPLE rvalue, else gimplify it into
5851 a temporary, make sure and register it to be renamed if necessary,
5852 and finally return the temporary. Put the statements to compute
5853 EXP before the current statement in BSI. */
5856 gimplify_val (block_stmt_iterator
*bsi
, tree type
, tree exp
)
5858 tree t
, new_stmt
, orig_stmt
;
5860 if (is_gimple_val (exp
))
5863 t
= make_rename_temp (type
, NULL
);
5864 new_stmt
= build (MODIFY_EXPR
, type
, t
, exp
);
5866 orig_stmt
= bsi_stmt (*bsi
);
5867 SET_EXPR_LOCUS (new_stmt
, EXPR_LOCUS (orig_stmt
));
5868 TREE_BLOCK (new_stmt
) = TREE_BLOCK (orig_stmt
);
5870 bsi_insert_before (bsi
, new_stmt
, BSI_SAME_STMT
);
5875 /* Build a ternary operation and gimplify it. Emit code before BSI.
5876 Return the gimple_val holding the result. */
5879 gimplify_build3 (block_stmt_iterator
*bsi
, enum tree_code code
,
5880 tree type
, tree a
, tree b
, tree c
)
5884 ret
= fold (build3 (code
, type
, a
, b
, c
));
5887 return gimplify_val (bsi
, type
, ret
);
5890 /* Build a binary operation and gimplify it. Emit code before BSI.
5891 Return the gimple_val holding the result. */
5894 gimplify_build2 (block_stmt_iterator
*bsi
, enum tree_code code
,
5895 tree type
, tree a
, tree b
)
5899 ret
= fold (build2 (code
, type
, a
, b
));
5902 return gimplify_val (bsi
, type
, ret
);
5905 /* Build a unary operation and gimplify it. Emit code before BSI.
5906 Return the gimple_val holding the result. */
5909 gimplify_build1 (block_stmt_iterator
*bsi
, enum tree_code code
, tree type
,
5914 ret
= fold (build1 (code
, type
, a
));
5917 return gimplify_val (bsi
, type
, ret
);
5922 /* Emit return warnings. */
5925 execute_warn_function_return (void)
5927 #ifdef USE_MAPPED_LOCATION
5928 source_location location
;
5936 if (warn_missing_noreturn
5937 && !TREE_THIS_VOLATILE (cfun
->decl
)
5938 && EDGE_COUNT (EXIT_BLOCK_PTR
->preds
) == 0
5939 && !lang_hooks
.function
.missing_noreturn_ok_p (cfun
->decl
))
5940 warning ("%Jfunction might be possible candidate for "
5941 "attribute %<noreturn%>",
5944 /* If we have a path to EXIT, then we do return. */
5945 if (TREE_THIS_VOLATILE (cfun
->decl
)
5946 && EDGE_COUNT (EXIT_BLOCK_PTR
->preds
) > 0)
5948 #ifdef USE_MAPPED_LOCATION
5949 location
= UNKNOWN_LOCATION
;
5953 FOR_EACH_EDGE (e
, ei
, EXIT_BLOCK_PTR
->preds
)
5955 last
= last_stmt (e
->src
);
5956 if (TREE_CODE (last
) == RETURN_EXPR
5957 #ifdef USE_MAPPED_LOCATION
5958 && (location
= EXPR_LOCATION (last
)) != UNKNOWN_LOCATION
)
5960 && (locus
= EXPR_LOCUS (last
)) != NULL
)
5964 #ifdef USE_MAPPED_LOCATION
5965 if (location
== UNKNOWN_LOCATION
)
5966 location
= cfun
->function_end_locus
;
5967 warning ("%H%<noreturn%> function does return", &location
);
5970 locus
= &cfun
->function_end_locus
;
5971 warning ("%H%<noreturn%> function does return", locus
);
5975 /* If we see "return;" in some basic block, then we do reach the end
5976 without returning a value. */
5977 else if (warn_return_type
5978 && !TREE_NO_WARNING (cfun
->decl
)
5979 && EDGE_COUNT (EXIT_BLOCK_PTR
->preds
) > 0
5980 && !VOID_TYPE_P (TREE_TYPE (TREE_TYPE (cfun
->decl
))))
5982 FOR_EACH_EDGE (e
, ei
, EXIT_BLOCK_PTR
->preds
)
5984 tree last
= last_stmt (e
->src
);
5985 if (TREE_CODE (last
) == RETURN_EXPR
5986 && TREE_OPERAND (last
, 0) == NULL
)
5988 #ifdef USE_MAPPED_LOCATION
5989 location
= EXPR_LOCATION (last
);
5990 if (location
== UNKNOWN_LOCATION
)
5991 location
= cfun
->function_end_locus
;
5992 warning ("%Hcontrol reaches end of non-void function", &location
);
5994 locus
= EXPR_LOCUS (last
);
5996 locus
= &cfun
->function_end_locus
;
5997 warning ("%Hcontrol reaches end of non-void function", locus
);
5999 TREE_NO_WARNING (cfun
->decl
) = 1;
6007 /* Given a basic block B which ends with a conditional and has
6008 precisely two successors, determine which of the edges is taken if
6009 the conditional is true and which is taken if the conditional is
6010 false. Set TRUE_EDGE and FALSE_EDGE appropriately. */
6013 extract_true_false_edges_from_block (basic_block b
,
6017 edge e
= EDGE_SUCC (b
, 0);
6019 if (e
->flags
& EDGE_TRUE_VALUE
)
6022 *false_edge
= EDGE_SUCC (b
, 1);
6027 *true_edge
= EDGE_SUCC (b
, 1);
6031 struct tree_opt_pass pass_warn_function_return
=
6035 execute_warn_function_return
, /* execute */
6038 0, /* static_pass_number */
6040 PROP_cfg
, /* properties_required */
6041 0, /* properties_provided */
6042 0, /* properties_destroyed */
6043 0, /* todo_flags_start */
6044 0, /* todo_flags_finish */
6048 #include "gt-tree-cfg.h"