1 /* Control flow functions for trees.
2 Copyright (C) 2001, 2002, 2003, 2004 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"
47 /* This file contains functions for building the Control Flow Graph (CFG)
48 for a function tree. */
50 /* Local declarations. */
52 /* Initial capacity for the basic block array. */
53 static const int initial_cfg_capacity
= 20;
55 /* Mapping of labels to their associated blocks. This can greatly speed up
56 building of the CFG in code with lots of gotos. */
57 static GTY(()) varray_type label_to_block_map
;
62 long num_merged_labels
;
65 static struct cfg_stats_d cfg_stats
;
67 /* Nonzero if we found a computed goto while building basic blocks. */
68 static bool found_computed_goto
;
70 /* Basic blocks and flowgraphs. */
71 static basic_block
create_bb (void *, void *, basic_block
);
72 static void create_block_annotation (basic_block
);
73 static void free_blocks_annotations (void);
74 static void clear_blocks_annotations (void);
75 static void make_blocks (tree
);
76 static void factor_computed_gotos (void);
79 static void make_edges (void);
80 static void make_ctrl_stmt_edges (basic_block
);
81 static void make_exit_edges (basic_block
);
82 static void make_cond_expr_edges (basic_block
);
83 static void make_switch_expr_edges (basic_block
);
84 static void make_goto_expr_edges (basic_block
);
85 static edge
tree_redirect_edge_and_branch (edge
, basic_block
);
86 static edge
tree_try_redirect_by_replacing_jump (edge
, basic_block
);
87 static void split_critical_edges (void);
89 /* Various helpers. */
90 static inline bool stmt_starts_bb_p (tree
, tree
);
91 static int tree_verify_flow_info (void);
92 static void tree_make_forwarder_block (edge
);
93 static bool thread_jumps (void);
94 static bool tree_forwarder_block_p (basic_block
);
95 static void bsi_commit_edge_inserts_1 (edge e
);
96 static void tree_cfg2vcg (FILE *);
98 /* Flowgraph optimization and cleanup. */
99 static void tree_merge_blocks (basic_block
, basic_block
);
100 static bool tree_can_merge_blocks_p (basic_block
, basic_block
);
101 static void remove_bb (basic_block
);
102 static bool cleanup_control_flow (void);
103 static bool cleanup_control_expr_graph (basic_block
, block_stmt_iterator
);
104 static edge
find_taken_edge_cond_expr (basic_block
, tree
);
105 static edge
find_taken_edge_switch_expr (basic_block
, tree
);
106 static tree
find_case_label_for_value (tree
, tree
);
107 static bool phi_alternatives_equal (basic_block
, edge
, edge
);
110 /*---------------------------------------------------------------------------
112 ---------------------------------------------------------------------------*/
114 /* Entry point to the CFG builder for trees. TP points to the list of
115 statements to be added to the flowgraph. */
118 build_tree_cfg (tree
*tp
)
120 /* Register specific tree functions. */
121 tree_register_cfg_hooks ();
123 /* Initialize rbi_pool. */
126 /* Initialize the basic block array. */
129 last_basic_block
= 0;
130 VARRAY_BB_INIT (basic_block_info
, initial_cfg_capacity
, "basic_block_info");
131 memset ((void *) &cfg_stats
, 0, sizeof (cfg_stats
));
133 /* Build a mapping of labels to their associated blocks. */
134 VARRAY_BB_INIT (label_to_block_map
, initial_cfg_capacity
,
135 "label to block map");
137 ENTRY_BLOCK_PTR
->next_bb
= EXIT_BLOCK_PTR
;
138 EXIT_BLOCK_PTR
->prev_bb
= ENTRY_BLOCK_PTR
;
140 found_computed_goto
= 0;
143 /* Computed gotos are hell to deal with, especially if there are
144 lots of them with a large number of destinations. So we factor
145 them to a common computed goto location before we build the
146 edge list. After we convert back to normal form, we will un-factor
147 the computed gotos since factoring introduces an unwanted jump. */
148 if (found_computed_goto
)
149 factor_computed_gotos ();
151 /* Make sure there is always at least one block, even if its empty. */
152 if (n_basic_blocks
== 0)
153 create_empty_bb (ENTRY_BLOCK_PTR
);
155 create_block_annotation (ENTRY_BLOCK_PTR
);
156 create_block_annotation (EXIT_BLOCK_PTR
);
158 /* Adjust the size of the array. */
159 VARRAY_GROW (basic_block_info
, n_basic_blocks
);
161 /* To speed up statement iterator walks, we first purge dead labels. */
162 cleanup_dead_labels ();
164 /* Group case nodes to reduce the number of edges.
165 We do this after cleaning up dead labels because otherwise we miss
166 a lot of obvious case merging opportunities. */
167 group_case_labels ();
169 /* Create the edges of the flowgraph. */
172 /* Debugging dumps. */
174 /* Write the flowgraph to a VCG file. */
176 int local_dump_flags
;
177 FILE *dump_file
= dump_begin (TDI_vcg
, &local_dump_flags
);
180 tree_cfg2vcg (dump_file
);
181 dump_end (TDI_vcg
, dump_file
);
185 /* Dump a textual representation of the flowgraph. */
187 dump_tree_cfg (dump_file
, dump_flags
);
191 execute_build_cfg (void)
193 build_tree_cfg (&DECL_SAVED_TREE (current_function_decl
));
196 struct tree_opt_pass pass_build_cfg
=
200 execute_build_cfg
, /* execute */
203 0, /* static_pass_number */
204 TV_TREE_CFG
, /* tv_id */
205 PROP_gimple_leh
, /* properties_required */
206 PROP_cfg
, /* properties_provided */
207 0, /* properties_destroyed */
208 0, /* todo_flags_start */
209 TODO_verify_stmts
/* todo_flags_finish */
212 /* Search the CFG for any computed gotos. If found, factor them to a
213 common computed goto site. Also record the location of that site so
214 that we can un-factor the gotos after we have converted back to
218 factor_computed_gotos (void)
221 tree factored_label_decl
= NULL
;
223 tree factored_computed_goto_label
= NULL
;
224 tree factored_computed_goto
= NULL
;
226 /* We know there are one or more computed gotos in this function.
227 Examine the last statement in each basic block to see if the block
228 ends with a computed goto. */
232 block_stmt_iterator bsi
= bsi_last (bb
);
237 last
= bsi_stmt (bsi
);
239 /* Ignore the computed goto we create when we factor the original
241 if (last
== factored_computed_goto
)
244 /* If the last statement is a computed goto, factor it. */
245 if (computed_goto_p (last
))
249 /* The first time we find a computed goto we need to create
250 the factored goto block and the variable each original
251 computed goto will use for their goto destination. */
252 if (! factored_computed_goto
)
254 basic_block new_bb
= create_empty_bb (bb
);
255 block_stmt_iterator new_bsi
= bsi_start (new_bb
);
257 /* Create the destination of the factored goto. Each original
258 computed goto will put its desired destination into this
259 variable and jump to the label we create immediately
261 var
= create_tmp_var (ptr_type_node
, "gotovar");
263 /* Build a label for the new block which will contain the
264 factored computed goto. */
265 factored_label_decl
= create_artificial_label ();
266 factored_computed_goto_label
267 = build1 (LABEL_EXPR
, void_type_node
, factored_label_decl
);
268 bsi_insert_after (&new_bsi
, factored_computed_goto_label
,
271 /* Build our new computed goto. */
272 factored_computed_goto
= build1 (GOTO_EXPR
, void_type_node
, var
);
273 bsi_insert_after (&new_bsi
, factored_computed_goto
,
277 /* Copy the original computed goto's destination into VAR. */
278 assignment
= build (MODIFY_EXPR
, ptr_type_node
,
279 var
, GOTO_DESTINATION (last
));
280 bsi_insert_before (&bsi
, assignment
, BSI_SAME_STMT
);
282 /* And re-vector the computed goto to the new destination. */
283 GOTO_DESTINATION (last
) = factored_label_decl
;
289 /* Create annotations for a single basic block. */
292 create_block_annotation (basic_block bb
)
294 /* Verify that the tree_annotations field is clear. */
295 if (bb
->tree_annotations
)
297 bb
->tree_annotations
= ggc_alloc_cleared (sizeof (struct bb_ann_d
));
301 /* Free the annotations for all the basic blocks. */
303 static void free_blocks_annotations (void)
305 clear_blocks_annotations ();
309 /* Clear the annotations for all the basic blocks. */
312 clear_blocks_annotations (void)
316 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
, NULL
, next_bb
)
317 bb
->tree_annotations
= NULL
;
321 /* Build a flowgraph for the statement_list STMT_LIST. */
324 make_blocks (tree stmt_list
)
326 tree_stmt_iterator i
= tsi_start (stmt_list
);
328 bool start_new_block
= true;
329 bool first_stmt_of_list
= true;
330 basic_block bb
= ENTRY_BLOCK_PTR
;
332 while (!tsi_end_p (i
))
339 /* If the statement starts a new basic block or if we have determined
340 in a previous pass that we need to create a new block for STMT, do
342 if (start_new_block
|| stmt_starts_bb_p (stmt
, prev_stmt
))
344 if (!first_stmt_of_list
)
345 stmt_list
= tsi_split_statement_list_before (&i
);
346 bb
= create_basic_block (stmt_list
, NULL
, bb
);
347 start_new_block
= false;
350 /* Now add STMT to BB and create the subgraphs for special statement
352 set_bb_for_stmt (stmt
, bb
);
354 if (computed_goto_p (stmt
))
355 found_computed_goto
= true;
357 /* If STMT is a basic block terminator, set START_NEW_BLOCK for the
359 if (stmt_ends_bb_p (stmt
))
360 start_new_block
= true;
363 first_stmt_of_list
= false;
368 /* Create and return a new empty basic block after bb AFTER. */
371 create_bb (void *h
, void *e
, basic_block after
)
378 /* Create and initialize a new basic block. */
380 memset (bb
, 0, sizeof (*bb
));
382 bb
->index
= last_basic_block
;
384 bb
->stmt_list
= h
? h
: alloc_stmt_list ();
386 /* Add the new block to the linked list of blocks. */
387 link_block (bb
, after
);
389 /* Grow the basic block array if needed. */
390 if ((size_t) last_basic_block
== VARRAY_SIZE (basic_block_info
))
392 size_t new_size
= last_basic_block
+ (last_basic_block
+ 3) / 4;
393 VARRAY_GROW (basic_block_info
, new_size
);
396 /* Add the newly created block to the array. */
397 BASIC_BLOCK (last_basic_block
) = bb
;
399 create_block_annotation (bb
);
404 initialize_bb_rbi (bb
);
409 /*---------------------------------------------------------------------------
411 ---------------------------------------------------------------------------*/
413 /* Join all the blocks in the flowgraph. */
420 /* Create an edge from entry to the first block with executable
422 make_edge (ENTRY_BLOCK_PTR
, BASIC_BLOCK (0), EDGE_FALLTHRU
);
424 /* Traverse basic block array placing edges. */
427 tree first
= first_stmt (bb
);
428 tree last
= last_stmt (bb
);
432 /* Edges for statements that always alter flow control. */
433 if (is_ctrl_stmt (last
))
434 make_ctrl_stmt_edges (bb
);
436 /* Edges for statements that sometimes alter flow control. */
437 if (is_ctrl_altering_stmt (last
))
438 make_exit_edges (bb
);
441 /* Finally, if no edges were created above, this is a regular
442 basic block that only needs a fallthru edge. */
443 if (bb
->succ
== NULL
)
444 make_edge (bb
, bb
->next_bb
, EDGE_FALLTHRU
);
447 /* We do not care about fake edges, so remove any that the CFG
448 builder inserted for completeness. */
449 remove_fake_exit_edges ();
451 /* Clean up the graph and warn for unreachable code. */
456 /* Create edges for control statement at basic block BB. */
459 make_ctrl_stmt_edges (basic_block bb
)
461 tree last
= last_stmt (bb
);
462 tree first
= first_stmt (bb
);
464 #if defined ENABLE_CHECKING
465 if (last
== NULL_TREE
)
469 if (TREE_CODE (first
) == LABEL_EXPR
470 && DECL_NONLOCAL (LABEL_EXPR_LABEL (first
)))
471 make_edge (ENTRY_BLOCK_PTR
, bb
, EDGE_ABNORMAL
);
473 switch (TREE_CODE (last
))
476 make_goto_expr_edges (bb
);
480 make_edge (bb
, EXIT_BLOCK_PTR
, 0);
484 make_cond_expr_edges (bb
);
488 make_switch_expr_edges (bb
);
492 make_eh_edges (last
);
493 /* Yet another NORETURN hack. */
494 if (bb
->succ
== NULL
)
495 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
504 /* Create exit edges for statements in block BB that alter the flow of
505 control. Statements that alter the control flow are 'goto', 'return'
506 and calls to non-returning functions. */
509 make_exit_edges (basic_block bb
)
511 tree last
= last_stmt (bb
), op
;
513 if (last
== NULL_TREE
)
516 switch (TREE_CODE (last
))
519 /* If this function receives a nonlocal goto, then we need to
520 make edges from this call site to all the nonlocal goto
522 if (TREE_SIDE_EFFECTS (last
)
523 && current_function_has_nonlocal_label
)
524 make_goto_expr_edges (bb
);
526 /* If this statement has reachable exception handlers, then
527 create abnormal edges to them. */
528 make_eh_edges (last
);
530 /* Some calls are known not to return. For such calls we create
533 We really need to revamp how we build edges so that it's not
534 such a bloody pain to avoid creating edges for this case since
535 all we do is remove these edges when we're done building the
537 if (call_expr_flags (last
) & (ECF_NORETURN
| ECF_LONGJMP
))
539 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
543 /* Don't forget the fall-thru edge. */
544 make_edge (bb
, bb
->next_bb
, EDGE_FALLTHRU
);
548 /* A MODIFY_EXPR may have a CALL_EXPR on its RHS and the CALL_EXPR
549 may have an abnormal edge. Search the RHS for this case and
550 create any required edges. */
551 op
= get_call_expr_in (last
);
552 if (op
&& TREE_SIDE_EFFECTS (op
)
553 && current_function_has_nonlocal_label
)
554 make_goto_expr_edges (bb
);
556 make_eh_edges (last
);
557 make_edge (bb
, bb
->next_bb
, EDGE_FALLTHRU
);
566 /* Create the edges for a COND_EXPR starting at block BB.
567 At this point, both clauses must contain only simple gotos. */
570 make_cond_expr_edges (basic_block bb
)
572 tree entry
= last_stmt (bb
);
573 basic_block then_bb
, else_bb
;
574 tree then_label
, else_label
;
576 #if defined ENABLE_CHECKING
577 if (entry
== NULL_TREE
|| TREE_CODE (entry
) != COND_EXPR
)
581 /* Entry basic blocks for each component. */
582 then_label
= GOTO_DESTINATION (COND_EXPR_THEN (entry
));
583 else_label
= GOTO_DESTINATION (COND_EXPR_ELSE (entry
));
584 then_bb
= label_to_block (then_label
);
585 else_bb
= label_to_block (else_label
);
587 make_edge (bb
, then_bb
, EDGE_TRUE_VALUE
);
588 make_edge (bb
, else_bb
, EDGE_FALSE_VALUE
);
592 /* Create the edges for a SWITCH_EXPR starting at block BB.
593 At this point, the switch body has been lowered and the
594 SWITCH_LABELS filled in, so this is in effect a multi-way branch. */
597 make_switch_expr_edges (basic_block bb
)
599 tree entry
= last_stmt (bb
);
603 vec
= SWITCH_LABELS (entry
);
604 n
= TREE_VEC_LENGTH (vec
);
606 for (i
= 0; i
< n
; ++i
)
608 tree lab
= CASE_LABEL (TREE_VEC_ELT (vec
, i
));
609 basic_block label_bb
= label_to_block (lab
);
610 make_edge (bb
, label_bb
, 0);
615 /* Return the basic block holding label DEST. */
618 label_to_block (tree dest
)
620 int uid
= LABEL_DECL_UID (dest
);
622 /* We would die hard when faced by undefined label. Emit label to
623 very first basic block. This will hopefully make even the dataflow
624 and undefined variable warnings quite right. */
625 if ((errorcount
|| sorrycount
) && uid
< 0)
627 block_stmt_iterator bsi
= bsi_start (BASIC_BLOCK (0));
630 stmt
= build1 (LABEL_EXPR
, void_type_node
, dest
);
631 bsi_insert_before (&bsi
, stmt
, BSI_NEW_STMT
);
632 uid
= LABEL_DECL_UID (dest
);
634 return VARRAY_BB (label_to_block_map
, uid
);
638 /* Create edges for a goto statement at block BB. */
641 make_goto_expr_edges (basic_block bb
)
644 basic_block target_bb
;
646 block_stmt_iterator last
= bsi_last (bb
);
648 goto_t
= bsi_stmt (last
);
650 /* If the last statement is not a GOTO (i.e., it is a RETURN_EXPR,
651 CALL_EXPR or MODIFY_EXPR), then the edge is an abnormal edge resulting
652 from a nonlocal goto. */
653 if (TREE_CODE (goto_t
) != GOTO_EXPR
)
655 dest
= error_mark_node
;
660 dest
= GOTO_DESTINATION (goto_t
);
663 /* A GOTO to a local label creates normal edges. */
664 if (simple_goto_p (goto_t
))
666 edge e
= make_edge (bb
, label_to_block (dest
), EDGE_FALLTHRU
);
667 #ifdef USE_MAPPED_LOCATION
668 e
->goto_locus
= EXPR_LOCATION (goto_t
);
670 e
->goto_locus
= EXPR_LOCUS (goto_t
);
676 /* Nothing more to do for nonlocal gotos. */
677 if (TREE_CODE (dest
) == LABEL_DECL
)
680 /* Computed gotos remain. */
683 /* Look for the block starting with the destination label. In the
684 case of a computed goto, make an edge to any label block we find
686 FOR_EACH_BB (target_bb
)
688 block_stmt_iterator bsi
;
690 for (bsi
= bsi_start (target_bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
692 tree target
= bsi_stmt (bsi
);
694 if (TREE_CODE (target
) != LABEL_EXPR
)
698 /* Computed GOTOs. Make an edge to every label block that has
699 been marked as a potential target for a computed goto. */
700 (FORCED_LABEL (LABEL_EXPR_LABEL (target
)) && for_call
== 0)
701 /* Nonlocal GOTO target. Make an edge to every label block
702 that has been marked as a potential target for a nonlocal
704 || (DECL_NONLOCAL (LABEL_EXPR_LABEL (target
)) && for_call
== 1))
706 make_edge (bb
, target_bb
, EDGE_ABNORMAL
);
712 /* Degenerate case of computed goto with no labels. */
713 if (!for_call
&& !bb
->succ
)
714 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
718 /*---------------------------------------------------------------------------
720 ---------------------------------------------------------------------------*/
722 /* Remove unreachable blocks and other miscellaneous clean up work. */
725 cleanup_tree_cfg (void)
727 bool something_changed
= true;
729 timevar_push (TV_TREE_CLEANUP_CFG
);
731 /* These three transformations can cascade, so we iterate on them until
733 while (something_changed
)
735 something_changed
= cleanup_control_flow ();
736 something_changed
|= thread_jumps ();
737 something_changed
|= delete_unreachable_blocks ();
740 /* Merging the blocks creates no new opportunities for the other
741 optimizations, so do it here. */
746 #ifdef ENABLE_CHECKING
749 timevar_pop (TV_TREE_CLEANUP_CFG
);
753 /* Cleanup useless labels in basic blocks. This is something we wish
754 to do early because it allows us to group case labels before creating
755 the edges for the CFG, and it speeds up block statement iterators in
757 We only run this pass once, running it more than once is probably not
760 /* A map from basic block index to the leading label of that block. */
761 static tree
*label_for_bb
;
763 /* Callback for for_each_eh_region. Helper for cleanup_dead_labels. */
765 update_eh_label (struct eh_region
*region
)
767 tree old_label
= get_eh_region_tree_label (region
);
771 basic_block bb
= label_to_block (old_label
);
773 /* ??? After optimizing, there may be EH regions with labels
774 that have already been removed from the function body, so
775 there is no basic block for them. */
779 new_label
= label_for_bb
[bb
->index
];
780 set_eh_region_tree_label (region
, new_label
);
784 /* Given LABEL return the first label in the same basic block. */
786 main_block_label (tree label
)
788 basic_block bb
= label_to_block (label
);
790 /* label_to_block possibly inserted undefined label into the chain. */
791 if (!label_for_bb
[bb
->index
])
792 label_for_bb
[bb
->index
] = label
;
793 return label_for_bb
[bb
->index
];
796 /* Cleanup redundant labels. This is a three-steo process:
797 1) Find the leading label for each block.
798 2) Redirect all references to labels to the leading labels.
799 3) Cleanup all useless labels. */
802 cleanup_dead_labels (void)
805 label_for_bb
= xcalloc (last_basic_block
, sizeof (tree
));
807 /* Find a suitable label for each block. We use the first user-defined
808 label is there is one, or otherwise just the first label we see. */
811 block_stmt_iterator i
;
813 for (i
= bsi_start (bb
); !bsi_end_p (i
); bsi_next (&i
))
815 tree label
, stmt
= bsi_stmt (i
);
817 if (TREE_CODE (stmt
) != LABEL_EXPR
)
820 label
= LABEL_EXPR_LABEL (stmt
);
822 /* If we have not yet seen a label for the current block,
823 remember this one and see if there are more labels. */
824 if (! label_for_bb
[bb
->index
])
826 label_for_bb
[bb
->index
] = label
;
830 /* If we did see a label for the current block already, but it
831 is an artificially created label, replace it if the current
832 label is a user defined label. */
833 if (! DECL_ARTIFICIAL (label
)
834 && DECL_ARTIFICIAL (label_for_bb
[bb
->index
]))
836 label_for_bb
[bb
->index
] = label
;
842 /* Now redirect all jumps/branches to the selected label.
843 First do so for each block ending in a control statement. */
846 tree stmt
= last_stmt (bb
);
850 switch (TREE_CODE (stmt
))
854 tree true_branch
, false_branch
;
856 true_branch
= COND_EXPR_THEN (stmt
);
857 false_branch
= COND_EXPR_ELSE (stmt
);
859 GOTO_DESTINATION (true_branch
)
860 = main_block_label (GOTO_DESTINATION (true_branch
));
861 GOTO_DESTINATION (false_branch
)
862 = main_block_label (GOTO_DESTINATION (false_branch
));
870 tree vec
= SWITCH_LABELS (stmt
);
871 size_t n
= TREE_VEC_LENGTH (vec
);
873 /* Replace all destination labels. */
874 for (i
= 0; i
< n
; ++i
)
875 CASE_LABEL (TREE_VEC_ELT (vec
, i
))
876 = main_block_label (CASE_LABEL (TREE_VEC_ELT (vec
, i
)));
881 /* We have to handle GOTO_EXPRs until they're removed, and we don't
882 remove them until after we've created the CFG edges. */
884 if (! computed_goto_p (stmt
))
886 GOTO_DESTINATION (stmt
)
887 = main_block_label (GOTO_DESTINATION (stmt
));
896 for_each_eh_region (update_eh_label
);
898 /* Finally, purge dead labels. All user-defined labels and labels that
899 can be the target of non-local gotos are preserved. */
902 block_stmt_iterator i
;
903 tree label_for_this_bb
= label_for_bb
[bb
->index
];
905 if (! label_for_this_bb
)
908 for (i
= bsi_start (bb
); !bsi_end_p (i
); )
910 tree label
, stmt
= bsi_stmt (i
);
912 if (TREE_CODE (stmt
) != LABEL_EXPR
)
915 label
= LABEL_EXPR_LABEL (stmt
);
917 if (label
== label_for_this_bb
918 || ! DECL_ARTIFICIAL (label
)
919 || DECL_NONLOCAL (label
))
929 /* Look for blocks ending in a multiway branch (a SWITCH_EXPR in GIMPLE),
930 and scan the sorted vector of cases. Combine the ones jumping to the
932 Eg. three separate entries 1: 2: 3: become one entry 1..3: */
935 group_case_labels (void)
941 tree stmt
= last_stmt (bb
);
942 if (stmt
&& TREE_CODE (stmt
) == SWITCH_EXPR
)
944 tree labels
= SWITCH_LABELS (stmt
);
945 int old_size
= TREE_VEC_LENGTH (labels
);
946 int i
, j
, new_size
= old_size
;
947 tree default_label
= TREE_VEC_ELT (labels
, old_size
- 1);
949 /* Look for possible opportunities to merge cases.
950 Ignore the last element of the label vector because it
951 must be the default case. */
953 while (i
< old_size
- 2)
955 tree base_case
, base_label
, base_high
, type
;
956 base_case
= TREE_VEC_ELT (labels
, i
);
961 base_label
= CASE_LABEL (base_case
);
963 /* Discard cases that have the same destination as the
965 if (base_label
== default_label
)
967 TREE_VEC_ELT (labels
, i
) = NULL_TREE
;
972 type
= TREE_TYPE (CASE_LOW (base_case
));
973 base_high
= CASE_HIGH (base_case
) ?
974 CASE_HIGH (base_case
) : CASE_LOW (base_case
);
976 /* Try to merge case labels. Break out when we reach the end
977 of the label vector or when we cannot merge the next case
978 label with the current one. */
979 while (i
< old_size
- 2)
981 tree merge_case
= TREE_VEC_ELT (labels
, ++i
);
982 tree merge_label
= CASE_LABEL (merge_case
);
983 tree t
= int_const_binop (PLUS_EXPR
, base_high
,
984 integer_one_node
, 1);
986 /* Merge the cases if they jump to the same place,
987 and their ranges are consecutive. */
988 if (merge_label
== base_label
989 && tree_int_cst_equal (CASE_LOW (merge_case
), t
))
991 base_high
= CASE_HIGH (merge_case
) ?
992 CASE_HIGH (merge_case
) : CASE_LOW (merge_case
);
993 CASE_HIGH (base_case
) = base_high
;
994 TREE_VEC_ELT (labels
, i
) = NULL_TREE
;
1002 /* Compress the case labels in the label vector, and adjust the
1003 length of the vector. */
1004 for (i
= 0, j
= 0; i
< new_size
; i
++)
1006 while (! TREE_VEC_ELT (labels
, j
))
1008 TREE_VEC_ELT (labels
, i
) = TREE_VEC_ELT (labels
, j
++);
1010 TREE_VEC_LENGTH (labels
) = new_size
;
1015 /* Checks whether we can merge block B into block A. */
1018 tree_can_merge_blocks_p (basic_block a
, basic_block b
)
1021 block_stmt_iterator bsi
;
1024 || a
->succ
->succ_next
)
1027 if (a
->succ
->flags
& EDGE_ABNORMAL
)
1030 if (a
->succ
->dest
!= b
)
1033 if (b
== EXIT_BLOCK_PTR
)
1036 if (b
->pred
->pred_next
)
1039 /* If A ends by a statement causing exceptions or something similar, we
1040 cannot merge the blocks. */
1041 stmt
= last_stmt (a
);
1042 if (stmt
&& stmt_ends_bb_p (stmt
))
1045 /* Do not allow a block with only a non-local label to be merged. */
1046 if (stmt
&& TREE_CODE (stmt
) == LABEL_EXPR
1047 && DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt
)))
1050 /* There may be no phi nodes at the start of b. Most of these degenerate
1051 phi nodes should be cleaned up by kill_redundant_phi_nodes. */
1055 /* Do not remove user labels. */
1056 for (bsi
= bsi_start (b
); !bsi_end_p (bsi
); bsi_next (&bsi
))
1058 stmt
= bsi_stmt (bsi
);
1059 if (TREE_CODE (stmt
) != LABEL_EXPR
)
1061 if (!DECL_ARTIFICIAL (LABEL_EXPR_LABEL (stmt
)))
1069 /* Merge block B into block A. */
1072 tree_merge_blocks (basic_block a
, basic_block b
)
1074 block_stmt_iterator bsi
;
1075 tree_stmt_iterator last
;
1078 fprintf (dump_file
, "Merging blocks %d and %d\n", a
->index
, b
->index
);
1080 /* Ensure that B follows A. */
1081 move_block_after (b
, a
);
1083 if (!(a
->succ
->flags
& EDGE_FALLTHRU
))
1087 && stmt_ends_bb_p (last_stmt (a
)))
1090 /* Remove labels from B and set bb_for_stmt to A for other statements. */
1091 for (bsi
= bsi_start (b
); !bsi_end_p (bsi
);)
1093 if (TREE_CODE (bsi_stmt (bsi
)) == LABEL_EXPR
)
1097 set_bb_for_stmt (bsi_stmt (bsi
), a
);
1102 /* Merge the chains. */
1103 last
= tsi_last (a
->stmt_list
);
1104 tsi_link_after (&last
, b
->stmt_list
, TSI_NEW_STMT
);
1105 b
->stmt_list
= NULL
;
1109 /* Walk the function tree removing unnecessary statements.
1111 * Empty statement nodes are removed
1113 * Unnecessary TRY_FINALLY and TRY_CATCH blocks are removed
1115 * Unnecessary COND_EXPRs are removed
1117 * Some unnecessary BIND_EXPRs are removed
1119 Clearly more work could be done. The trick is doing the analysis
1120 and removal fast enough to be a net improvement in compile times.
1122 Note that when we remove a control structure such as a COND_EXPR
1123 BIND_EXPR, or TRY block, we will need to repeat this optimization pass
1124 to ensure we eliminate all the useless code. */
1135 static void remove_useless_stmts_1 (tree
*, struct rus_data
*);
1138 remove_useless_stmts_warn_notreached (tree stmt
)
1140 if (EXPR_HAS_LOCATION (stmt
))
1142 location_t loc
= EXPR_LOCATION (stmt
);
1143 warning ("%Hwill never be executed", &loc
);
1147 switch (TREE_CODE (stmt
))
1149 case STATEMENT_LIST
:
1151 tree_stmt_iterator i
;
1152 for (i
= tsi_start (stmt
); !tsi_end_p (i
); tsi_next (&i
))
1153 if (remove_useless_stmts_warn_notreached (tsi_stmt (i
)))
1159 if (remove_useless_stmts_warn_notreached (COND_EXPR_COND (stmt
)))
1161 if (remove_useless_stmts_warn_notreached (COND_EXPR_THEN (stmt
)))
1163 if (remove_useless_stmts_warn_notreached (COND_EXPR_ELSE (stmt
)))
1167 case TRY_FINALLY_EXPR
:
1168 case TRY_CATCH_EXPR
:
1169 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt
, 0)))
1171 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt
, 1)))
1176 return remove_useless_stmts_warn_notreached (CATCH_BODY (stmt
));
1177 case EH_FILTER_EXPR
:
1178 return remove_useless_stmts_warn_notreached (EH_FILTER_FAILURE (stmt
));
1180 return remove_useless_stmts_warn_notreached (BIND_EXPR_BLOCK (stmt
));
1183 /* Not a live container. */
1191 remove_useless_stmts_cond (tree
*stmt_p
, struct rus_data
*data
)
1193 tree then_clause
, else_clause
, cond
;
1194 bool save_has_label
, then_has_label
, else_has_label
;
1196 save_has_label
= data
->has_label
;
1197 data
->has_label
= false;
1198 data
->last_goto
= NULL
;
1200 remove_useless_stmts_1 (&COND_EXPR_THEN (*stmt_p
), data
);
1202 then_has_label
= data
->has_label
;
1203 data
->has_label
= false;
1204 data
->last_goto
= NULL
;
1206 remove_useless_stmts_1 (&COND_EXPR_ELSE (*stmt_p
), data
);
1208 else_has_label
= data
->has_label
;
1209 data
->has_label
= save_has_label
| then_has_label
| else_has_label
;
1212 then_clause
= COND_EXPR_THEN (*stmt_p
);
1213 else_clause
= COND_EXPR_ELSE (*stmt_p
);
1214 cond
= COND_EXPR_COND (*stmt_p
);
1216 /* If neither arm does anything at all, we can remove the whole IF. */
1217 if (!TREE_SIDE_EFFECTS (then_clause
) && !TREE_SIDE_EFFECTS (else_clause
))
1219 *stmt_p
= build_empty_stmt ();
1220 data
->repeat
= true;
1223 /* If there are no reachable statements in an arm, then we can
1224 zap the entire conditional. */
1225 else if (integer_nonzerop (cond
) && !else_has_label
)
1227 if (warn_notreached
)
1228 remove_useless_stmts_warn_notreached (else_clause
);
1229 *stmt_p
= then_clause
;
1230 data
->repeat
= true;
1232 else if (integer_zerop (cond
) && !then_has_label
)
1234 if (warn_notreached
)
1235 remove_useless_stmts_warn_notreached (then_clause
);
1236 *stmt_p
= else_clause
;
1237 data
->repeat
= true;
1240 /* Check a couple of simple things on then/else with single stmts. */
1243 tree then_stmt
= expr_only (then_clause
);
1244 tree else_stmt
= expr_only (else_clause
);
1246 /* Notice branches to a common destination. */
1247 if (then_stmt
&& else_stmt
1248 && TREE_CODE (then_stmt
) == GOTO_EXPR
1249 && TREE_CODE (else_stmt
) == GOTO_EXPR
1250 && (GOTO_DESTINATION (then_stmt
) == GOTO_DESTINATION (else_stmt
)))
1252 *stmt_p
= then_stmt
;
1253 data
->repeat
= true;
1256 /* If the THEN/ELSE clause merely assigns a value to a variable or
1257 parameter which is already known to contain that value, then
1258 remove the useless THEN/ELSE clause. */
1259 else if (TREE_CODE (cond
) == VAR_DECL
|| TREE_CODE (cond
) == PARM_DECL
)
1262 && TREE_CODE (else_stmt
) == MODIFY_EXPR
1263 && TREE_OPERAND (else_stmt
, 0) == cond
1264 && integer_zerop (TREE_OPERAND (else_stmt
, 1)))
1265 COND_EXPR_ELSE (*stmt_p
) = alloc_stmt_list ();
1267 else if ((TREE_CODE (cond
) == EQ_EXPR
|| TREE_CODE (cond
) == NE_EXPR
)
1268 && (TREE_CODE (TREE_OPERAND (cond
, 0)) == VAR_DECL
1269 || TREE_CODE (TREE_OPERAND (cond
, 0)) == PARM_DECL
)
1270 && TREE_CONSTANT (TREE_OPERAND (cond
, 1)))
1272 tree stmt
= (TREE_CODE (cond
) == EQ_EXPR
1273 ? then_stmt
: else_stmt
);
1274 tree
*location
= (TREE_CODE (cond
) == EQ_EXPR
1275 ? &COND_EXPR_THEN (*stmt_p
)
1276 : &COND_EXPR_ELSE (*stmt_p
));
1279 && TREE_CODE (stmt
) == MODIFY_EXPR
1280 && TREE_OPERAND (stmt
, 0) == TREE_OPERAND (cond
, 0)
1281 && TREE_OPERAND (stmt
, 1) == TREE_OPERAND (cond
, 1))
1282 *location
= alloc_stmt_list ();
1286 /* Protect GOTOs in the arm of COND_EXPRs from being removed. They
1287 would be re-introduced during lowering. */
1288 data
->last_goto
= NULL
;
1293 remove_useless_stmts_tf (tree
*stmt_p
, struct rus_data
*data
)
1295 bool save_may_branch
, save_may_throw
;
1296 bool this_may_branch
, this_may_throw
;
1298 /* Collect may_branch and may_throw information for the body only. */
1299 save_may_branch
= data
->may_branch
;
1300 save_may_throw
= data
->may_throw
;
1301 data
->may_branch
= false;
1302 data
->may_throw
= false;
1303 data
->last_goto
= NULL
;
1305 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p
, 0), data
);
1307 this_may_branch
= data
->may_branch
;
1308 this_may_throw
= data
->may_throw
;
1309 data
->may_branch
|= save_may_branch
;
1310 data
->may_throw
|= save_may_throw
;
1311 data
->last_goto
= NULL
;
1313 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p
, 1), data
);
1315 /* If the body is empty, then we can emit the FINALLY block without
1316 the enclosing TRY_FINALLY_EXPR. */
1317 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p
, 0)))
1319 *stmt_p
= TREE_OPERAND (*stmt_p
, 1);
1320 data
->repeat
= true;
1323 /* If the handler is empty, then we can emit the TRY block without
1324 the enclosing TRY_FINALLY_EXPR. */
1325 else if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p
, 1)))
1327 *stmt_p
= TREE_OPERAND (*stmt_p
, 0);
1328 data
->repeat
= true;
1331 /* If the body neither throws, nor branches, then we can safely
1332 string the TRY and FINALLY blocks together. */
1333 else if (!this_may_branch
&& !this_may_throw
)
1335 tree stmt
= *stmt_p
;
1336 *stmt_p
= TREE_OPERAND (stmt
, 0);
1337 append_to_statement_list (TREE_OPERAND (stmt
, 1), stmt_p
);
1338 data
->repeat
= true;
1344 remove_useless_stmts_tc (tree
*stmt_p
, struct rus_data
*data
)
1346 bool save_may_throw
, this_may_throw
;
1347 tree_stmt_iterator i
;
1350 /* Collect may_throw information for the body only. */
1351 save_may_throw
= data
->may_throw
;
1352 data
->may_throw
= false;
1353 data
->last_goto
= NULL
;
1355 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p
, 0), data
);
1357 this_may_throw
= data
->may_throw
;
1358 data
->may_throw
= save_may_throw
;
1360 /* If the body cannot throw, then we can drop the entire TRY_CATCH_EXPR. */
1361 if (!this_may_throw
)
1363 if (warn_notreached
)
1364 remove_useless_stmts_warn_notreached (TREE_OPERAND (*stmt_p
, 1));
1365 *stmt_p
= TREE_OPERAND (*stmt_p
, 0);
1366 data
->repeat
= true;
1370 /* Process the catch clause specially. We may be able to tell that
1371 no exceptions propagate past this point. */
1373 this_may_throw
= true;
1374 i
= tsi_start (TREE_OPERAND (*stmt_p
, 1));
1375 stmt
= tsi_stmt (i
);
1376 data
->last_goto
= NULL
;
1378 switch (TREE_CODE (stmt
))
1381 for (; !tsi_end_p (i
); tsi_next (&i
))
1383 stmt
= tsi_stmt (i
);
1384 /* If we catch all exceptions, then the body does not
1385 propagate exceptions past this point. */
1386 if (CATCH_TYPES (stmt
) == NULL
)
1387 this_may_throw
= false;
1388 data
->last_goto
= NULL
;
1389 remove_useless_stmts_1 (&CATCH_BODY (stmt
), data
);
1393 case EH_FILTER_EXPR
:
1394 if (EH_FILTER_MUST_NOT_THROW (stmt
))
1395 this_may_throw
= false;
1396 else if (EH_FILTER_TYPES (stmt
) == NULL
)
1397 this_may_throw
= false;
1398 remove_useless_stmts_1 (&EH_FILTER_FAILURE (stmt
), data
);
1402 /* Otherwise this is a cleanup. */
1403 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p
, 1), data
);
1405 /* If the cleanup is empty, then we can emit the TRY block without
1406 the enclosing TRY_CATCH_EXPR. */
1407 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p
, 1)))
1409 *stmt_p
= TREE_OPERAND (*stmt_p
, 0);
1410 data
->repeat
= true;
1414 data
->may_throw
|= this_may_throw
;
1419 remove_useless_stmts_bind (tree
*stmt_p
, struct rus_data
*data
)
1423 /* First remove anything underneath the BIND_EXPR. */
1424 remove_useless_stmts_1 (&BIND_EXPR_BODY (*stmt_p
), data
);
1426 /* If the BIND_EXPR has no variables, then we can pull everything
1427 up one level and remove the BIND_EXPR, unless this is the toplevel
1428 BIND_EXPR for the current function or an inlined function.
1430 When this situation occurs we will want to apply this
1431 optimization again. */
1432 block
= BIND_EXPR_BLOCK (*stmt_p
);
1433 if (BIND_EXPR_VARS (*stmt_p
) == NULL_TREE
1434 && *stmt_p
!= DECL_SAVED_TREE (current_function_decl
)
1436 || ! BLOCK_ABSTRACT_ORIGIN (block
)
1437 || (TREE_CODE (BLOCK_ABSTRACT_ORIGIN (block
))
1440 *stmt_p
= BIND_EXPR_BODY (*stmt_p
);
1441 data
->repeat
= true;
1447 remove_useless_stmts_goto (tree
*stmt_p
, struct rus_data
*data
)
1449 tree dest
= GOTO_DESTINATION (*stmt_p
);
1451 data
->may_branch
= true;
1452 data
->last_goto
= NULL
;
1454 /* Record the last goto expr, so that we can delete it if unnecessary. */
1455 if (TREE_CODE (dest
) == LABEL_DECL
)
1456 data
->last_goto
= stmt_p
;
1461 remove_useless_stmts_label (tree
*stmt_p
, struct rus_data
*data
)
1463 tree label
= LABEL_EXPR_LABEL (*stmt_p
);
1465 data
->has_label
= true;
1467 /* We do want to jump across non-local label receiver code. */
1468 if (DECL_NONLOCAL (label
))
1469 data
->last_goto
= NULL
;
1471 else if (data
->last_goto
&& GOTO_DESTINATION (*data
->last_goto
) == label
)
1473 *data
->last_goto
= build_empty_stmt ();
1474 data
->repeat
= true;
1477 /* ??? Add something here to delete unused labels. */
1481 /* If the function is "const" or "pure", then clear TREE_SIDE_EFFECTS on its
1482 decl. This allows us to eliminate redundant or useless
1483 calls to "const" functions.
1485 Gimplifier already does the same operation, but we may notice functions
1486 being const and pure once their calls has been gimplified, so we need
1487 to update the flag. */
1490 update_call_expr_flags (tree call
)
1492 tree decl
= get_callee_fndecl (call
);
1495 if (call_expr_flags (call
) & (ECF_CONST
| ECF_PURE
))
1496 TREE_SIDE_EFFECTS (call
) = 0;
1497 if (TREE_NOTHROW (decl
))
1498 TREE_NOTHROW (call
) = 1;
1502 /* T is CALL_EXPR. Set current_function_calls_* flags. */
1505 notice_special_calls (tree t
)
1507 int flags
= call_expr_flags (t
);
1509 if (flags
& ECF_MAY_BE_ALLOCA
)
1510 current_function_calls_alloca
= true;
1511 if (flags
& ECF_RETURNS_TWICE
)
1512 current_function_calls_setjmp
= true;
1516 /* Clear flags set by notice_special_calls. Used by dead code removal
1517 to update the flags. */
1520 clear_special_calls (void)
1522 current_function_calls_alloca
= false;
1523 current_function_calls_setjmp
= false;
1528 remove_useless_stmts_1 (tree
*tp
, struct rus_data
*data
)
1532 switch (TREE_CODE (t
))
1535 remove_useless_stmts_cond (tp
, data
);
1538 case TRY_FINALLY_EXPR
:
1539 remove_useless_stmts_tf (tp
, data
);
1542 case TRY_CATCH_EXPR
:
1543 remove_useless_stmts_tc (tp
, data
);
1547 remove_useless_stmts_bind (tp
, data
);
1551 remove_useless_stmts_goto (tp
, data
);
1555 remove_useless_stmts_label (tp
, data
);
1560 data
->last_goto
= NULL
;
1561 data
->may_branch
= true;
1566 data
->last_goto
= NULL
;
1567 notice_special_calls (t
);
1568 update_call_expr_flags (t
);
1569 if (tree_could_throw_p (t
))
1570 data
->may_throw
= true;
1574 data
->last_goto
= NULL
;
1576 op
= get_call_expr_in (t
);
1579 update_call_expr_flags (op
);
1580 notice_special_calls (op
);
1582 if (tree_could_throw_p (t
))
1583 data
->may_throw
= true;
1586 case STATEMENT_LIST
:
1588 tree_stmt_iterator i
= tsi_start (t
);
1589 while (!tsi_end_p (i
))
1592 if (IS_EMPTY_STMT (t
))
1598 remove_useless_stmts_1 (tsi_stmt_ptr (i
), data
);
1601 if (TREE_CODE (t
) == STATEMENT_LIST
)
1603 tsi_link_before (&i
, t
, TSI_SAME_STMT
);
1613 data
->last_goto
= NULL
;
1617 data
->last_goto
= NULL
;
1623 remove_useless_stmts (void)
1625 struct rus_data data
;
1627 clear_special_calls ();
1631 memset (&data
, 0, sizeof (data
));
1632 remove_useless_stmts_1 (&DECL_SAVED_TREE (current_function_decl
), &data
);
1634 while (data
.repeat
);
1638 struct tree_opt_pass pass_remove_useless_stmts
=
1640 "useless", /* name */
1642 remove_useless_stmts
, /* execute */
1645 0, /* static_pass_number */
1647 PROP_gimple_any
, /* properties_required */
1648 0, /* properties_provided */
1649 0, /* properties_destroyed */
1650 0, /* todo_flags_start */
1651 TODO_dump_func
/* todo_flags_finish */
1655 /* Remove obviously useless statements in basic block BB. */
1658 cfg_remove_useless_stmts_bb (basic_block bb
)
1660 block_stmt_iterator bsi
;
1661 tree stmt
= NULL_TREE
;
1662 tree cond
, var
= NULL_TREE
, val
= NULL_TREE
;
1663 struct var_ann_d
*ann
;
1665 /* Check whether we come here from a condition, and if so, get the
1668 || bb
->pred
->pred_next
1669 || !(bb
->pred
->flags
& (EDGE_TRUE_VALUE
| EDGE_FALSE_VALUE
)))
1672 cond
= COND_EXPR_COND (last_stmt (bb
->pred
->src
));
1674 if (TREE_CODE (cond
) == VAR_DECL
|| TREE_CODE (cond
) == PARM_DECL
)
1677 val
= (bb
->pred
->flags
& EDGE_FALSE_VALUE
1678 ? boolean_false_node
: boolean_true_node
);
1680 else if (TREE_CODE (cond
) == TRUTH_NOT_EXPR
1681 && (TREE_CODE (TREE_OPERAND (cond
, 0)) == VAR_DECL
1682 || TREE_CODE (TREE_OPERAND (cond
, 0)) == PARM_DECL
))
1684 var
= TREE_OPERAND (cond
, 0);
1685 val
= (bb
->pred
->flags
& EDGE_FALSE_VALUE
1686 ? boolean_true_node
: boolean_false_node
);
1690 if (bb
->pred
->flags
& EDGE_FALSE_VALUE
)
1691 cond
= invert_truthvalue (cond
);
1692 if (TREE_CODE (cond
) == EQ_EXPR
1693 && (TREE_CODE (TREE_OPERAND (cond
, 0)) == VAR_DECL
1694 || TREE_CODE (TREE_OPERAND (cond
, 0)) == PARM_DECL
)
1695 && (TREE_CODE (TREE_OPERAND (cond
, 1)) == VAR_DECL
1696 || TREE_CODE (TREE_OPERAND (cond
, 1)) == PARM_DECL
1697 || TREE_CONSTANT (TREE_OPERAND (cond
, 1))))
1699 var
= TREE_OPERAND (cond
, 0);
1700 val
= TREE_OPERAND (cond
, 1);
1706 /* Only work for normal local variables. */
1707 ann
= var_ann (var
);
1710 || TREE_ADDRESSABLE (var
))
1713 if (! TREE_CONSTANT (val
))
1715 ann
= var_ann (val
);
1718 || TREE_ADDRESSABLE (val
))
1722 /* Ignore floating point variables, since comparison behaves weird for
1724 if (FLOAT_TYPE_P (TREE_TYPE (var
)))
1727 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
);)
1729 stmt
= bsi_stmt (bsi
);
1731 /* If the THEN/ELSE clause merely assigns a value to a variable/parameter
1732 which is already known to contain that value, then remove the useless
1733 THEN/ELSE clause. */
1734 if (TREE_CODE (stmt
) == MODIFY_EXPR
1735 && TREE_OPERAND (stmt
, 0) == var
1736 && operand_equal_p (val
, TREE_OPERAND (stmt
, 1), 0))
1742 /* Invalidate the var if we encounter something that could modify it. */
1743 if (TREE_CODE (stmt
) == ASM_EXPR
1744 || (TREE_CODE (stmt
) == MODIFY_EXPR
1745 && TREE_OPERAND (stmt
, 0) == var
))
1753 /* A CFG-aware version of remove_useless_stmts. */
1756 cfg_remove_useless_stmts (void)
1760 #ifdef ENABLE_CHECKING
1761 verify_flow_info ();
1766 cfg_remove_useless_stmts_bb (bb
);
1771 /* Remove PHI nodes associated with basic block BB and all edges out of BB. */
1774 remove_phi_nodes_and_edges_for_unreachable_block (basic_block bb
)
1778 /* Since this block is no longer reachable, we can just delete all
1779 of its PHI nodes. */
1780 phi
= phi_nodes (bb
);
1783 tree next
= PHI_CHAIN (phi
);
1784 remove_phi_node (phi
, NULL_TREE
, bb
);
1788 /* Remove edges to BB's successors. */
1789 while (bb
->succ
!= NULL
)
1790 ssa_remove_edge (bb
->succ
);
1794 /* Remove statements of basic block BB. */
1797 remove_bb (basic_block bb
)
1799 block_stmt_iterator i
;
1800 source_locus loc
= 0;
1804 fprintf (dump_file
, "Removing basic block %d\n", bb
->index
);
1805 if (dump_flags
& TDF_DETAILS
)
1807 dump_bb (bb
, dump_file
, 0);
1808 fprintf (dump_file
, "\n");
1812 /* Remove all the instructions in the block. */
1813 for (i
= bsi_start (bb
); !bsi_end_p (i
); bsi_remove (&i
))
1815 tree stmt
= bsi_stmt (i
);
1817 set_bb_for_stmt (stmt
, NULL
);
1819 /* Don't warn for removed gotos. Gotos are often removed due to
1820 jump threading, thus resulting in bogus warnings. Not great,
1821 since this way we lose warnings for gotos in the original
1822 program that are indeed unreachable. */
1823 if (TREE_CODE (stmt
) != GOTO_EXPR
&& EXPR_HAS_LOCATION (stmt
) && !loc
)
1824 #ifdef USE_MAPPED_LOCATION
1825 loc
= EXPR_LOCATION (stmt
);
1827 loc
= EXPR_LOCUS (stmt
);
1831 /* If requested, give a warning that the first statement in the
1832 block is unreachable. We walk statements backwards in the
1833 loop above, so the last statement we process is the first statement
1835 if (warn_notreached
&& loc
)
1836 #ifdef USE_MAPPED_LOCATION
1837 warning ("%Hwill never be executed", &loc
);
1839 warning ("%Hwill never be executed", loc
);
1842 remove_phi_nodes_and_edges_for_unreachable_block (bb
);
1846 /* Examine BB to determine if it is a forwarding block (a block which only
1847 transfers control to a new destination). If BB is a forwarding block,
1848 then return the edge leading to the ultimate destination. */
1851 tree_block_forwards_to (basic_block bb
)
1853 block_stmt_iterator bsi
;
1854 bb_ann_t ann
= bb_ann (bb
);
1857 /* If this block is not forwardable, then avoid useless work. */
1858 if (! ann
->forwardable
)
1861 /* Set this block to not be forwardable. This prevents infinite loops since
1862 any block currently under examination is considered non-forwardable. */
1863 ann
->forwardable
= 0;
1865 /* No forwarding is possible if this block is a special block (ENTRY/EXIT),
1866 this block has more than one successor, this block's single successor is
1867 reached via an abnormal edge, this block has phi nodes, or this block's
1868 single successor has phi nodes. */
1869 if (bb
== EXIT_BLOCK_PTR
1870 || bb
== ENTRY_BLOCK_PTR
1872 || bb
->succ
->succ_next
1873 || bb
->succ
->dest
== EXIT_BLOCK_PTR
1874 || (bb
->succ
->flags
& EDGE_ABNORMAL
) != 0
1876 || phi_nodes (bb
->succ
->dest
))
1879 /* Walk past any labels at the start of this block. */
1880 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
1882 stmt
= bsi_stmt (bsi
);
1883 if (TREE_CODE (stmt
) != LABEL_EXPR
)
1887 /* If we reached the end of this block we may be able to optimize this
1889 if (bsi_end_p (bsi
))
1893 /* Recursive call to pick up chains of forwarding blocks. */
1894 dest
= tree_block_forwards_to (bb
->succ
->dest
);
1896 /* If none found, we forward to bb->succ at minimum. */
1900 ann
->forwardable
= 1;
1904 /* No forwarding possible. */
1909 /* Try to remove superfluous control structures. */
1912 cleanup_control_flow (void)
1915 block_stmt_iterator bsi
;
1916 bool retval
= false;
1921 bsi
= bsi_last (bb
);
1923 if (bsi_end_p (bsi
))
1926 stmt
= bsi_stmt (bsi
);
1927 if (TREE_CODE (stmt
) == COND_EXPR
1928 || TREE_CODE (stmt
) == SWITCH_EXPR
)
1929 retval
|= cleanup_control_expr_graph (bb
, bsi
);
1935 /* Disconnect an unreachable block in the control expression starting
1939 cleanup_control_expr_graph (basic_block bb
, block_stmt_iterator bsi
)
1942 bool retval
= false;
1943 tree expr
= bsi_stmt (bsi
), val
;
1945 if (bb
->succ
->succ_next
)
1949 switch (TREE_CODE (expr
))
1952 val
= COND_EXPR_COND (expr
);
1956 val
= SWITCH_COND (expr
);
1957 if (TREE_CODE (val
) != INTEGER_CST
)
1965 taken_edge
= find_taken_edge (bb
, val
);
1969 /* Remove all the edges except the one that is always executed. */
1970 for (e
= bb
->succ
; e
; e
= next
)
1972 next
= e
->succ_next
;
1973 if (e
!= taken_edge
)
1975 taken_edge
->probability
+= e
->probability
;
1976 taken_edge
->count
+= e
->count
;
1977 ssa_remove_edge (e
);
1981 if (taken_edge
->probability
> REG_BR_PROB_BASE
)
1982 taken_edge
->probability
= REG_BR_PROB_BASE
;
1985 taken_edge
= bb
->succ
;
1988 taken_edge
->flags
= EDGE_FALLTHRU
;
1990 /* We removed some paths from the cfg. */
1991 if (dom_computed
[CDI_DOMINATORS
] >= DOM_CONS_OK
)
1992 dom_computed
[CDI_DOMINATORS
] = DOM_CONS_OK
;
1998 /* Given a control block BB and a predicate VAL, return the edge that
1999 will be taken out of the block. If VAL does not match a unique
2000 edge, NULL is returned. */
2003 find_taken_edge (basic_block bb
, tree val
)
2007 stmt
= last_stmt (bb
);
2009 #if defined ENABLE_CHECKING
2010 if (stmt
== NULL_TREE
|| !is_ctrl_stmt (stmt
))
2014 /* If VAL is a predicate of the form N RELOP N, where N is an
2015 SSA_NAME, we can always determine its truth value (except when
2016 doing floating point comparisons that may involve NaNs). */
2018 && TREE_CODE_CLASS (TREE_CODE (val
)) == '<'
2019 && TREE_OPERAND (val
, 0) == TREE_OPERAND (val
, 1)
2020 && TREE_CODE (TREE_OPERAND (val
, 0)) == SSA_NAME
2021 && (TREE_CODE (TREE_TYPE (TREE_OPERAND (val
, 0))) != REAL_TYPE
2022 || !HONOR_NANS (TYPE_MODE (TREE_TYPE (TREE_OPERAND (val
, 0))))))
2024 enum tree_code code
= TREE_CODE (val
);
2026 if (code
== EQ_EXPR
|| code
== LE_EXPR
|| code
== GE_EXPR
)
2027 val
= boolean_true_node
;
2028 else if (code
== LT_EXPR
|| code
== GT_EXPR
|| code
== NE_EXPR
)
2029 val
= boolean_false_node
;
2032 /* If VAL is not a constant, we can't determine which edge might
2034 if (val
== NULL
|| !really_constant_p (val
))
2037 if (TREE_CODE (stmt
) == COND_EXPR
)
2038 return find_taken_edge_cond_expr (bb
, val
);
2040 if (TREE_CODE (stmt
) == SWITCH_EXPR
)
2041 return find_taken_edge_switch_expr (bb
, val
);
2047 /* Given a constant value VAL and the entry block BB to a COND_EXPR
2048 statement, determine which of the two edges will be taken out of the
2049 block. Return NULL if either edge may be taken. */
2052 find_taken_edge_cond_expr (basic_block bb
, tree val
)
2054 edge true_edge
, false_edge
;
2056 extract_true_false_edges_from_block (bb
, &true_edge
, &false_edge
);
2058 /* If both edges of the branch lead to the same basic block, it doesn't
2059 matter which edge is taken. */
2060 if (true_edge
->dest
== false_edge
->dest
)
2063 /* Otherwise, try to determine which branch of the if() will be taken.
2064 If VAL is a constant but it can't be reduced to a 0 or a 1, then
2065 we don't really know which edge will be taken at runtime. This
2066 may happen when comparing addresses (e.g., if (&var1 == 4)). */
2067 if (integer_nonzerop (val
))
2069 else if (integer_zerop (val
))
2076 /* Given a constant value VAL and the entry block BB to a SWITCH_EXPR
2077 statement, determine which edge will be taken out of the block. Return
2078 NULL if any edge may be taken. */
2081 find_taken_edge_switch_expr (basic_block bb
, tree val
)
2083 tree switch_expr
, taken_case
;
2084 basic_block dest_bb
;
2087 if (TREE_CODE (val
) != INTEGER_CST
)
2090 switch_expr
= last_stmt (bb
);
2091 taken_case
= find_case_label_for_value (switch_expr
, val
);
2092 dest_bb
= label_to_block (CASE_LABEL (taken_case
));
2094 e
= find_edge (bb
, dest_bb
);
2101 /* Return the CASE_LABEL_EXPR that SWITCH_EXPR will take for VAL.
2102 We can make optimal use here of the fact that the case labels are
2103 sorted: We can do a binary search for a case matching VAL. */
2106 find_case_label_for_value (tree switch_expr
, tree val
)
2108 tree vec
= SWITCH_LABELS (switch_expr
);
2109 size_t low
, high
, n
= TREE_VEC_LENGTH (vec
);
2110 tree default_case
= TREE_VEC_ELT (vec
, n
- 1);
2112 for (low
= -1, high
= n
- 1; high
- low
> 1; )
2114 size_t i
= (high
+ low
) / 2;
2115 tree t
= TREE_VEC_ELT (vec
, i
);
2118 /* Cache the result of comparing CASE_LOW and val. */
2119 cmp
= tree_int_cst_compare (CASE_LOW (t
), val
);
2126 if (CASE_HIGH (t
) == NULL
)
2128 /* A singe-valued case label. */
2134 /* A case range. We can only handle integer ranges. */
2135 if (cmp
<= 0 && tree_int_cst_compare (CASE_HIGH (t
), val
) >= 0)
2140 return default_case
;
2144 /* If all the PHI nodes in DEST have alternatives for E1 and E2 and
2145 those alternatives are equal in each of the PHI nodes, then return
2146 true, else return false. */
2149 phi_alternatives_equal (basic_block dest
, edge e1
, edge e2
)
2151 tree phi
, val1
, val2
;
2154 for (phi
= phi_nodes (dest
); phi
; phi
= PHI_CHAIN (phi
))
2156 n1
= phi_arg_from_edge (phi
, e1
);
2157 n2
= phi_arg_from_edge (phi
, e2
);
2159 #ifdef ENABLE_CHECKING
2160 if (n1
< 0 || n2
< 0)
2164 val1
= PHI_ARG_DEF (phi
, n1
);
2165 val2
= PHI_ARG_DEF (phi
, n2
);
2167 if (!operand_equal_p (val1
, val2
, 0))
2175 /* Computing the Dominance Frontier:
2177 As described in Morgan, section 3.5, this may be done simply by
2178 walking the dominator tree bottom-up, computing the frontier for
2179 the children before the parent. When considering a block B,
2180 there are two cases:
2182 (1) A flow graph edge leaving B that does not lead to a child
2183 of B in the dominator tree must be a block that is either equal
2184 to B or not dominated by B. Such blocks belong in the frontier
2187 (2) Consider a block X in the frontier of one of the children C
2188 of B. If X is not equal to B and is not dominated by B, it
2189 is in the frontier of B. */
2192 compute_dominance_frontiers_1 (bitmap
*frontiers
, basic_block bb
, sbitmap done
)
2197 SET_BIT (done
, bb
->index
);
2199 /* Do the frontier of the children first. Not all children in the
2200 dominator tree (blocks dominated by this one) are children in the
2201 CFG, so check all blocks. */
2202 for (c
= first_dom_son (CDI_DOMINATORS
, bb
);
2204 c
= next_dom_son (CDI_DOMINATORS
, c
))
2206 if (! TEST_BIT (done
, c
->index
))
2207 compute_dominance_frontiers_1 (frontiers
, c
, done
);
2210 /* Find blocks conforming to rule (1) above. */
2211 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
2213 if (e
->dest
== EXIT_BLOCK_PTR
)
2215 if (get_immediate_dominator (CDI_DOMINATORS
, e
->dest
) != bb
)
2216 bitmap_set_bit (frontiers
[bb
->index
], e
->dest
->index
);
2219 /* Find blocks conforming to rule (2). */
2220 for (c
= first_dom_son (CDI_DOMINATORS
, bb
);
2222 c
= next_dom_son (CDI_DOMINATORS
, c
))
2226 EXECUTE_IF_SET_IN_BITMAP (frontiers
[c
->index
], 0, x
,
2228 if (get_immediate_dominator (CDI_DOMINATORS
, BASIC_BLOCK (x
)) != bb
)
2229 bitmap_set_bit (frontiers
[bb
->index
], x
);
2236 compute_dominance_frontiers (bitmap
*frontiers
)
2238 sbitmap done
= sbitmap_alloc (last_basic_block
);
2240 timevar_push (TV_DOM_FRONTIERS
);
2242 sbitmap_zero (done
);
2244 compute_dominance_frontiers_1 (frontiers
, ENTRY_BLOCK_PTR
->succ
->dest
, done
);
2246 sbitmap_free (done
);
2248 timevar_pop (TV_DOM_FRONTIERS
);
2253 /*---------------------------------------------------------------------------
2255 ---------------------------------------------------------------------------*/
2257 /* Dump tree-specific information of block BB to file OUTF. */
2260 tree_dump_bb (basic_block bb
, FILE *outf
, int indent
)
2262 dump_generic_bb (outf
, bb
, indent
, TDF_VOPS
);
2266 /* Dump a basic block on stderr. */
2269 debug_tree_bb (basic_block bb
)
2271 dump_bb (bb
, stderr
, 0);
2275 /* Dump basic block with index N on stderr. */
2278 debug_tree_bb_n (int n
)
2280 debug_tree_bb (BASIC_BLOCK (n
));
2281 return BASIC_BLOCK (n
);
2285 /* Dump the CFG on stderr.
2287 FLAGS are the same used by the tree dumping functions
2288 (see TDF_* in tree.h). */
2291 debug_tree_cfg (int flags
)
2293 dump_tree_cfg (stderr
, flags
);
2297 /* Dump the program showing basic block boundaries on the given FILE.
2299 FLAGS are the same used by the tree dumping functions (see TDF_* in
2303 dump_tree_cfg (FILE *file
, int flags
)
2305 if (flags
& TDF_DETAILS
)
2307 const char *funcname
2308 = lang_hooks
.decl_printable_name (current_function_decl
, 2);
2311 fprintf (file
, ";; Function %s\n\n", funcname
);
2312 fprintf (file
, ";; \n%d basic blocks, %d edges, last basic block %d.\n\n",
2313 n_basic_blocks
, n_edges
, last_basic_block
);
2315 brief_dump_cfg (file
);
2316 fprintf (file
, "\n");
2319 if (flags
& TDF_STATS
)
2320 dump_cfg_stats (file
);
2322 dump_function_to_file (current_function_decl
, file
, flags
| TDF_BLOCKS
);
2326 /* Dump CFG statistics on FILE. */
2329 dump_cfg_stats (FILE *file
)
2331 static long max_num_merged_labels
= 0;
2332 unsigned long size
, total
= 0;
2335 const char * const fmt_str
= "%-30s%-13s%12s\n";
2336 const char * const fmt_str_1
= "%-30s%13d%11lu%c\n";
2337 const char * const fmt_str_3
= "%-43s%11lu%c\n";
2338 const char *funcname
2339 = lang_hooks
.decl_printable_name (current_function_decl
, 2);
2342 fprintf (file
, "\nCFG Statistics for %s\n\n", funcname
);
2344 fprintf (file
, "---------------------------------------------------------\n");
2345 fprintf (file
, fmt_str
, "", " Number of ", "Memory");
2346 fprintf (file
, fmt_str
, "", " instances ", "used ");
2347 fprintf (file
, "---------------------------------------------------------\n");
2349 size
= n_basic_blocks
* sizeof (struct basic_block_def
);
2351 fprintf (file
, fmt_str_1
, "Basic blocks", n_basic_blocks
,
2352 SCALE (size
), LABEL (size
));
2358 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
2361 size
= n_edges
* sizeof (struct edge_def
);
2363 fprintf (file
, fmt_str_1
, "Edges", n_edges
, SCALE (size
), LABEL (size
));
2365 size
= n_basic_blocks
* sizeof (struct bb_ann_d
);
2367 fprintf (file
, fmt_str_1
, "Basic block annotations", n_basic_blocks
,
2368 SCALE (size
), LABEL (size
));
2370 fprintf (file
, "---------------------------------------------------------\n");
2371 fprintf (file
, fmt_str_3
, "Total memory used by CFG data", SCALE (total
),
2373 fprintf (file
, "---------------------------------------------------------\n");
2374 fprintf (file
, "\n");
2376 if (cfg_stats
.num_merged_labels
> max_num_merged_labels
)
2377 max_num_merged_labels
= cfg_stats
.num_merged_labels
;
2379 fprintf (file
, "Coalesced label blocks: %ld (Max so far: %ld)\n",
2380 cfg_stats
.num_merged_labels
, max_num_merged_labels
);
2382 fprintf (file
, "\n");
2386 /* Dump CFG statistics on stderr. Keep extern so that it's always
2387 linked in the final executable. */
2390 debug_cfg_stats (void)
2392 dump_cfg_stats (stderr
);
2396 /* Dump the flowgraph to a .vcg FILE. */
2399 tree_cfg2vcg (FILE *file
)
2403 const char *funcname
2404 = lang_hooks
.decl_printable_name (current_function_decl
, 2);
2406 /* Write the file header. */
2407 fprintf (file
, "graph: { title: \"%s\"\n", funcname
);
2408 fprintf (file
, "node: { title: \"ENTRY\" label: \"ENTRY\" }\n");
2409 fprintf (file
, "node: { title: \"EXIT\" label: \"EXIT\" }\n");
2411 /* Write blocks and edges. */
2412 for (e
= ENTRY_BLOCK_PTR
->succ
; e
; e
= e
->succ_next
)
2414 fprintf (file
, "edge: { sourcename: \"ENTRY\" targetname: \"%d\"",
2417 if (e
->flags
& EDGE_FAKE
)
2418 fprintf (file
, " linestyle: dotted priority: 10");
2420 fprintf (file
, " linestyle: solid priority: 100");
2422 fprintf (file
, " }\n");
2428 enum tree_code head_code
, end_code
;
2429 const char *head_name
, *end_name
;
2432 tree first
= first_stmt (bb
);
2433 tree last
= last_stmt (bb
);
2437 head_code
= TREE_CODE (first
);
2438 head_name
= tree_code_name
[head_code
];
2439 head_line
= get_lineno (first
);
2442 head_name
= "no-statement";
2446 end_code
= TREE_CODE (last
);
2447 end_name
= tree_code_name
[end_code
];
2448 end_line
= get_lineno (last
);
2451 end_name
= "no-statement";
2453 fprintf (file
, "node: { title: \"%d\" label: \"#%d\\n%s (%d)\\n%s (%d)\"}\n",
2454 bb
->index
, bb
->index
, head_name
, head_line
, end_name
,
2457 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
2459 if (e
->dest
== EXIT_BLOCK_PTR
)
2460 fprintf (file
, "edge: { sourcename: \"%d\" targetname: \"EXIT\"", bb
->index
);
2462 fprintf (file
, "edge: { sourcename: \"%d\" targetname: \"%d\"", bb
->index
, e
->dest
->index
);
2464 if (e
->flags
& EDGE_FAKE
)
2465 fprintf (file
, " priority: 10 linestyle: dotted");
2467 fprintf (file
, " priority: 100 linestyle: solid");
2469 fprintf (file
, " }\n");
2472 if (bb
->next_bb
!= EXIT_BLOCK_PTR
)
2476 fputs ("}\n\n", file
);
2481 /*---------------------------------------------------------------------------
2482 Miscellaneous helpers
2483 ---------------------------------------------------------------------------*/
2485 /* Return true if T represents a stmt that always transfers control. */
2488 is_ctrl_stmt (tree t
)
2490 return (TREE_CODE (t
) == COND_EXPR
2491 || TREE_CODE (t
) == SWITCH_EXPR
2492 || TREE_CODE (t
) == GOTO_EXPR
2493 || TREE_CODE (t
) == RETURN_EXPR
2494 || TREE_CODE (t
) == RESX_EXPR
);
2498 /* Return true if T is a statement that may alter the flow of control
2499 (e.g., a call to a non-returning function). */
2502 is_ctrl_altering_stmt (tree t
)
2506 #if defined ENABLE_CHECKING
2511 call
= get_call_expr_in (t
);
2514 /* A non-pure/const CALL_EXPR alters flow control if the current
2515 function has nonlocal labels. */
2516 if (TREE_SIDE_EFFECTS (call
) && current_function_has_nonlocal_label
)
2519 /* A CALL_EXPR also alters control flow if it does not return. */
2520 if (call_expr_flags (call
) & (ECF_NORETURN
| ECF_LONGJMP
))
2524 /* If a statement can throw, it alters control flow. */
2525 return tree_can_throw_internal (t
);
2529 /* Return true if T is a computed goto. */
2532 computed_goto_p (tree t
)
2534 return (TREE_CODE (t
) == GOTO_EXPR
2535 && TREE_CODE (GOTO_DESTINATION (t
)) != LABEL_DECL
);
2539 /* Checks whether EXPR is a simple local goto. */
2542 simple_goto_p (tree expr
)
2544 return (TREE_CODE (expr
) == GOTO_EXPR
2545 && TREE_CODE (GOTO_DESTINATION (expr
)) == LABEL_DECL
2546 && (decl_function_context (GOTO_DESTINATION (expr
))
2547 == current_function_decl
));
2551 /* Return true if T should start a new basic block. PREV_T is the
2552 statement preceding T. It is used when T is a label or a case label.
2553 Labels should only start a new basic block if their previous statement
2554 wasn't a label. Otherwise, sequence of labels would generate
2555 unnecessary basic blocks that only contain a single label. */
2558 stmt_starts_bb_p (tree t
, tree prev_t
)
2560 enum tree_code code
;
2565 /* LABEL_EXPRs start a new basic block only if the preceding
2566 statement wasn't a label of the same type. This prevents the
2567 creation of consecutive blocks that have nothing but a single
2569 code
= TREE_CODE (t
);
2570 if (code
== LABEL_EXPR
)
2572 /* Nonlocal and computed GOTO targets always start a new block. */
2573 if (code
== LABEL_EXPR
2574 && (DECL_NONLOCAL (LABEL_EXPR_LABEL (t
))
2575 || FORCED_LABEL (LABEL_EXPR_LABEL (t
))))
2578 if (prev_t
&& TREE_CODE (prev_t
) == code
)
2580 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (prev_t
)))
2583 cfg_stats
.num_merged_labels
++;
2594 /* Return true if T should end a basic block. */
2597 stmt_ends_bb_p (tree t
)
2599 return is_ctrl_stmt (t
) || is_ctrl_altering_stmt (t
);
2603 /* Add gotos that used to be represented implicitly in the CFG. */
2606 disband_implicit_edges (void)
2609 block_stmt_iterator last
;
2615 last
= bsi_last (bb
);
2616 stmt
= last_stmt (bb
);
2618 if (stmt
&& TREE_CODE (stmt
) == COND_EXPR
)
2620 /* Remove superfluous gotos from COND_EXPR branches. Moved
2621 from cfg_remove_useless_stmts here since it violates the
2622 invariants for tree--cfg correspondence and thus fits better
2623 here where we do it anyway. */
2624 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
2626 if (e
->dest
!= bb
->next_bb
)
2629 if (e
->flags
& EDGE_TRUE_VALUE
)
2630 COND_EXPR_THEN (stmt
) = build_empty_stmt ();
2631 else if (e
->flags
& EDGE_FALSE_VALUE
)
2632 COND_EXPR_ELSE (stmt
) = build_empty_stmt ();
2635 e
->flags
|= EDGE_FALLTHRU
;
2641 if (stmt
&& TREE_CODE (stmt
) == RETURN_EXPR
)
2643 /* Remove the RETURN_EXPR if we may fall though to the exit
2646 || bb
->succ
->succ_next
2647 || bb
->succ
->dest
!= EXIT_BLOCK_PTR
)
2650 if (bb
->next_bb
== EXIT_BLOCK_PTR
2651 && !TREE_OPERAND (stmt
, 0))
2654 bb
->succ
->flags
|= EDGE_FALLTHRU
;
2659 /* There can be no fallthru edge if the last statement is a control
2661 if (stmt
&& is_ctrl_stmt (stmt
))
2664 /* Find a fallthru edge and emit the goto if necessary. */
2665 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
2666 if (e
->flags
& EDGE_FALLTHRU
)
2669 if (!e
|| e
->dest
== bb
->next_bb
)
2672 if (e
->dest
== EXIT_BLOCK_PTR
)
2675 label
= tree_block_label (e
->dest
);
2677 stmt
= build1 (GOTO_EXPR
, void_type_node
, label
);
2678 #ifdef USE_MAPPED_LOCATION
2679 SET_EXPR_LOCATION (stmt
, e
->goto_locus
);
2681 SET_EXPR_LOCUS (stmt
, e
->goto_locus
);
2683 bsi_insert_after (&last
, stmt
, BSI_NEW_STMT
);
2684 e
->flags
&= ~EDGE_FALLTHRU
;
2688 /* Remove block annotations and other datastructures. */
2691 delete_tree_cfg_annotations (void)
2694 if (n_basic_blocks
> 0)
2695 free_blocks_annotations ();
2697 label_to_block_map
= NULL
;
2704 /* Return the first statement in basic block BB. */
2707 first_stmt (basic_block bb
)
2709 block_stmt_iterator i
= bsi_start (bb
);
2710 return !bsi_end_p (i
) ? bsi_stmt (i
) : NULL_TREE
;
2714 /* Return the last statement in basic block BB. */
2717 last_stmt (basic_block bb
)
2719 block_stmt_iterator b
= bsi_last (bb
);
2720 return !bsi_end_p (b
) ? bsi_stmt (b
) : NULL_TREE
;
2724 /* Return a pointer to the last statement in block BB. */
2727 last_stmt_ptr (basic_block bb
)
2729 block_stmt_iterator last
= bsi_last (bb
);
2730 return !bsi_end_p (last
) ? bsi_stmt_ptr (last
) : NULL
;
2734 /* Return the last statement of an otherwise empty block. Return NULL
2735 if the block is totally empty, or if it contains more than one
2739 last_and_only_stmt (basic_block bb
)
2741 block_stmt_iterator i
= bsi_last (bb
);
2747 last
= bsi_stmt (i
);
2752 /* Empty statements should no longer appear in the instruction stream.
2753 Everything that might have appeared before should be deleted by
2754 remove_useless_stmts, and the optimizers should just bsi_remove
2755 instead of smashing with build_empty_stmt.
2757 Thus the only thing that should appear here in a block containing
2758 one executable statement is a label. */
2759 prev
= bsi_stmt (i
);
2760 if (TREE_CODE (prev
) == LABEL_EXPR
)
2767 /* Mark BB as the basic block holding statement T. */
2770 set_bb_for_stmt (tree t
, basic_block bb
)
2772 if (TREE_CODE (t
) == STATEMENT_LIST
)
2774 tree_stmt_iterator i
;
2775 for (i
= tsi_start (t
); !tsi_end_p (i
); tsi_next (&i
))
2776 set_bb_for_stmt (tsi_stmt (i
), bb
);
2780 stmt_ann_t ann
= get_stmt_ann (t
);
2783 /* If the statement is a label, add the label to block-to-labels map
2784 so that we can speed up edge creation for GOTO_EXPRs. */
2785 if (TREE_CODE (t
) == LABEL_EXPR
)
2789 t
= LABEL_EXPR_LABEL (t
);
2790 uid
= LABEL_DECL_UID (t
);
2793 LABEL_DECL_UID (t
) = uid
= cfun
->last_label_uid
++;
2794 if (VARRAY_SIZE (label_to_block_map
) <= (unsigned) uid
)
2795 VARRAY_GROW (label_to_block_map
, 3 * uid
/ 2);
2799 #ifdef ENABLE_CHECKING
2800 /* We're moving an existing label. Make sure that we've
2801 removed it from the old block. */
2802 if (bb
&& VARRAY_BB (label_to_block_map
, uid
))
2806 VARRAY_BB (label_to_block_map
, uid
) = bb
;
2812 /* Insert statement (or statement list) T before the statement
2813 pointed-to by iterator I. M specifies how to update iterator I
2814 after insertion (see enum bsi_iterator_update). */
2817 bsi_insert_before (block_stmt_iterator
*i
, tree t
, enum bsi_iterator_update m
)
2819 set_bb_for_stmt (t
, i
->bb
);
2821 tsi_link_before (&i
->tsi
, t
, m
);
2825 /* Insert statement (or statement list) T after the statement
2826 pointed-to by iterator I. M specifies how to update iterator I
2827 after insertion (see enum bsi_iterator_update). */
2830 bsi_insert_after (block_stmt_iterator
*i
, tree t
, enum bsi_iterator_update m
)
2832 set_bb_for_stmt (t
, i
->bb
);
2834 tsi_link_after (&i
->tsi
, t
, m
);
2838 /* Remove the statement pointed to by iterator I. The iterator is updated
2839 to the next statement. */
2842 bsi_remove (block_stmt_iterator
*i
)
2844 tree t
= bsi_stmt (*i
);
2845 set_bb_for_stmt (t
, NULL
);
2847 tsi_delink (&i
->tsi
);
2851 /* Move the statement at FROM so it comes right after the statement at TO. */
2854 bsi_move_after (block_stmt_iterator
*from
, block_stmt_iterator
*to
)
2856 tree stmt
= bsi_stmt (*from
);
2858 bsi_insert_after (to
, stmt
, BSI_SAME_STMT
);
2862 /* Move the statement at FROM so it comes right before the statement at TO. */
2865 bsi_move_before (block_stmt_iterator
*from
, block_stmt_iterator
*to
)
2867 tree stmt
= bsi_stmt (*from
);
2869 bsi_insert_before (to
, stmt
, BSI_SAME_STMT
);
2873 /* Move the statement at FROM to the end of basic block BB. */
2876 bsi_move_to_bb_end (block_stmt_iterator
*from
, basic_block bb
)
2878 block_stmt_iterator last
= bsi_last (bb
);
2880 /* Have to check bsi_end_p because it could be an empty block. */
2881 if (!bsi_end_p (last
) && is_ctrl_stmt (bsi_stmt (last
)))
2882 bsi_move_before (from
, &last
);
2884 bsi_move_after (from
, &last
);
2888 /* Replace the contents of the statement pointed to by iterator BSI
2889 with STMT. If PRESERVE_EH_INFO is true, the exception handling
2890 information of the original statement is preserved. */
2893 bsi_replace (const block_stmt_iterator
*bsi
, tree stmt
, bool preserve_eh_info
)
2896 tree orig_stmt
= bsi_stmt (*bsi
);
2898 SET_EXPR_LOCUS (stmt
, EXPR_LOCUS (orig_stmt
));
2899 set_bb_for_stmt (stmt
, bsi
->bb
);
2901 /* Preserve EH region information from the original statement, if
2902 requested by the caller. */
2903 if (preserve_eh_info
)
2905 eh_region
= lookup_stmt_eh_region (orig_stmt
);
2907 add_stmt_to_eh_region (stmt
, eh_region
);
2910 *bsi_stmt_ptr (*bsi
) = stmt
;
2915 /* Insert the statement pointed-to by BSI into edge E. Every attempt
2916 is made to place the statement in an existing basic block, but
2917 sometimes that isn't possible. When it isn't possible, the edge is
2918 split and the statement is added to the new block.
2920 In all cases, the returned *BSI points to the correct location. The
2921 return value is true if insertion should be done after the location,
2922 or false if it should be done before the location. */
2925 tree_find_edge_insert_loc (edge e
, block_stmt_iterator
*bsi
)
2927 basic_block dest
, src
;
2933 /* If the destination has one predecessor which has no PHI nodes,
2934 insert there. Except for the exit block.
2936 The requirement for no PHI nodes could be relaxed. Basically we
2937 would have to examine the PHIs to prove that none of them used
2938 the value set by the statement we want to insert on E. That
2939 hardly seems worth the effort. */
2940 if (dest
->pred
->pred_next
== NULL
2941 && ! phi_nodes (dest
)
2942 && dest
!= EXIT_BLOCK_PTR
)
2944 *bsi
= bsi_start (dest
);
2945 if (bsi_end_p (*bsi
))
2948 /* Make sure we insert after any leading labels. */
2949 tmp
= bsi_stmt (*bsi
);
2950 while (TREE_CODE (tmp
) == LABEL_EXPR
)
2953 if (bsi_end_p (*bsi
))
2955 tmp
= bsi_stmt (*bsi
);
2958 if (bsi_end_p (*bsi
))
2960 *bsi
= bsi_last (dest
);
2967 /* If the source has one successor, the edge is not abnormal and
2968 the last statement does not end a basic block, insert there.
2969 Except for the entry block. */
2971 if ((e
->flags
& EDGE_ABNORMAL
) == 0
2972 && src
->succ
->succ_next
== NULL
2973 && src
!= ENTRY_BLOCK_PTR
)
2975 *bsi
= bsi_last (src
);
2976 if (bsi_end_p (*bsi
))
2979 tmp
= bsi_stmt (*bsi
);
2980 if (!stmt_ends_bb_p (tmp
))
2983 /* Insert code just before returning the value. We may need to decompose
2984 the return in the case it contains non-trivial operand. */
2985 if (TREE_CODE (tmp
) == RETURN_EXPR
)
2987 tree op
= TREE_OPERAND (tmp
, 0);
2988 if (!is_gimple_val (op
))
2990 if (TREE_CODE (op
) != MODIFY_EXPR
)
2992 bsi_insert_before (bsi
, op
, BSI_NEW_STMT
);
2993 TREE_OPERAND (tmp
, 0) = TREE_OPERAND (op
, 0);
3000 /* Otherwise, create a new basic block, and split this edge. */
3001 dest
= split_edge (e
);
3007 /* This routine will commit all pending edge insertions, creating any new
3008 basic blocks which are necessary.
3010 If specified, NEW_BLOCKS returns a count of the number of new basic
3011 blocks which were created. */
3014 bsi_commit_edge_inserts (int *new_blocks
)
3020 blocks
= n_basic_blocks
;
3022 bsi_commit_edge_inserts_1 (ENTRY_BLOCK_PTR
->succ
);
3025 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
3026 bsi_commit_edge_inserts_1 (e
);
3029 *new_blocks
= n_basic_blocks
- blocks
;
3033 /* Commit insertions pending at edge E. */
3036 bsi_commit_edge_inserts_1 (edge e
)
3038 if (PENDING_STMT (e
))
3040 block_stmt_iterator bsi
;
3041 tree stmt
= PENDING_STMT (e
);
3043 PENDING_STMT (e
) = NULL_TREE
;
3045 if (tree_find_edge_insert_loc (e
, &bsi
))
3046 bsi_insert_after (&bsi
, stmt
, BSI_NEW_STMT
);
3048 bsi_insert_before (&bsi
, stmt
, BSI_NEW_STMT
);
3053 /* Add STMT to the pending list of edge E. No actual insertion is
3054 made until a call to bsi_commit_edge_inserts () is made. */
3057 bsi_insert_on_edge (edge e
, tree stmt
)
3059 append_to_statement_list (stmt
, &PENDING_STMT (e
));
3063 /*---------------------------------------------------------------------------
3064 Tree specific functions for CFG manipulation
3065 ---------------------------------------------------------------------------*/
3067 /* Split a (typically critical) edge EDGE_IN. Return the new block.
3068 Abort on abnormal edges. */
3071 tree_split_edge (edge edge_in
)
3073 basic_block new_bb
, after_bb
, dest
, src
;
3078 /* Abnormal edges cannot be split. */
3079 if (edge_in
->flags
& EDGE_ABNORMAL
)
3083 dest
= edge_in
->dest
;
3085 /* Place the new block in the block list. Try to keep the new block
3086 near its "logical" location. This is of most help to humans looking
3087 at debugging dumps. */
3088 for (e
= dest
->pred
; e
; e
= e
->pred_next
)
3089 if (e
->src
->next_bb
== dest
)
3092 after_bb
= dest
->prev_bb
;
3094 after_bb
= edge_in
->src
;
3096 new_bb
= create_empty_bb (after_bb
);
3097 new_edge
= make_edge (new_bb
, dest
, EDGE_FALLTHRU
);
3099 /* Find all the PHI arguments on the original edge, and change them to
3100 the new edge. Do it before redirection, so that the argument does not
3102 for (phi
= phi_nodes (dest
); phi
; phi
= PHI_CHAIN (phi
))
3104 num_elem
= PHI_NUM_ARGS (phi
);
3105 for (i
= 0; i
< num_elem
; i
++)
3106 if (PHI_ARG_EDGE (phi
, i
) == edge_in
)
3108 PHI_ARG_EDGE (phi
, i
) = new_edge
;
3113 if (!redirect_edge_and_branch (edge_in
, new_bb
))
3116 if (PENDING_STMT (edge_in
))
3123 /* Return true when BB has label LABEL in it. */
3126 has_label_p (basic_block bb
, tree label
)
3128 block_stmt_iterator bsi
;
3130 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
3132 tree stmt
= bsi_stmt (bsi
);
3134 if (TREE_CODE (stmt
) != LABEL_EXPR
)
3136 if (LABEL_EXPR_LABEL (stmt
) == label
)
3143 /* Callback for walk_tree, check that all elements with address taken are
3144 properly noticed as such. */
3147 verify_expr (tree
*tp
, int *walk_subtrees
, void *data ATTRIBUTE_UNUSED
)
3154 /* Check operand N for being valid GIMPLE and give error MSG if not.
3155 We check for constants explicitly since they are not considered
3156 gimple invariants if they overflowed. */
3157 #define CHECK_OP(N, MSG) \
3158 do { if (TREE_CODE_CLASS (TREE_CODE (TREE_OPERAND (t, N))) != 'c' \
3159 && !is_gimple_val (TREE_OPERAND (t, N))) \
3160 { error (MSG); return TREE_OPERAND (t, N); }} while (0)
3162 switch (TREE_CODE (t
))
3165 if (SSA_NAME_IN_FREE_LIST (t
))
3167 error ("SSA name in freelist but still referenced");
3173 x
= TREE_OPERAND (t
, 0);
3174 if (TREE_CODE (x
) == BIT_FIELD_REF
3175 && is_gimple_reg (TREE_OPERAND (x
, 0)))
3177 error ("GIMPLE register modified with BIT_FIELD_REF");
3183 /* Skip any references (they will be checked when we recurse down the
3184 tree) and ensure that any variable used as a prefix is marked
3186 for (x
= TREE_OPERAND (t
, 0);
3187 (handled_component_p (x
)
3188 || TREE_CODE (x
) == REALPART_EXPR
3189 || TREE_CODE (x
) == IMAGPART_EXPR
);
3190 x
= TREE_OPERAND (x
, 0))
3193 if (TREE_CODE (x
) != VAR_DECL
&& TREE_CODE (x
) != PARM_DECL
)
3195 if (!TREE_ADDRESSABLE (x
))
3197 error ("address taken, but ADDRESSABLE bit not set");
3203 x
= TREE_OPERAND (t
, 0);
3204 if (TREE_CODE (TREE_TYPE (x
)) != BOOLEAN_TYPE
)
3206 error ("non-boolean used in condition");
3213 case FIX_TRUNC_EXPR
:
3215 case FIX_FLOOR_EXPR
:
3216 case FIX_ROUND_EXPR
:
3221 case NON_LVALUE_EXPR
:
3222 case TRUTH_NOT_EXPR
:
3223 CHECK_OP (0, "Invalid operand to unary operator");
3230 case ARRAY_RANGE_REF
:
3232 case VIEW_CONVERT_EXPR
:
3233 /* We have a nest of references. Verify that each of the operands
3234 that determine where to reference is either a constant or a variable,
3235 verify that the base is valid, and then show we've already checked
3237 while (TREE_CODE (t
) == REALPART_EXPR
|| TREE_CODE (t
) == IMAGPART_EXPR
3238 || handled_component_p (t
))
3240 if (TREE_CODE (t
) == COMPONENT_REF
&& TREE_OPERAND (t
, 2))
3241 CHECK_OP (2, "Invalid COMPONENT_REF offset operator");
3242 else if (TREE_CODE (t
) == ARRAY_REF
3243 || TREE_CODE (t
) == ARRAY_RANGE_REF
)
3245 CHECK_OP (1, "Invalid array index.");
3246 if (TREE_OPERAND (t
, 2))
3247 CHECK_OP (2, "Invalid array lower bound.");
3248 if (TREE_OPERAND (t
, 3))
3249 CHECK_OP (3, "Invalid array stride.");
3251 else if (TREE_CODE (t
) == BIT_FIELD_REF
)
3253 CHECK_OP (1, "Invalid operand to BIT_FIELD_REF");
3254 CHECK_OP (2, "Invalid operand to BIT_FIELD_REF");
3257 t
= TREE_OPERAND (t
, 0);
3260 if (TREE_CODE_CLASS (TREE_CODE (t
)) != 'c'
3261 && !is_gimple_lvalue (t
))
3263 error ("Invalid reference prefix.");
3275 case UNORDERED_EXPR
:
3286 case TRUNC_DIV_EXPR
:
3288 case FLOOR_DIV_EXPR
:
3289 case ROUND_DIV_EXPR
:
3290 case TRUNC_MOD_EXPR
:
3292 case FLOOR_MOD_EXPR
:
3293 case ROUND_MOD_EXPR
:
3295 case EXACT_DIV_EXPR
:
3305 CHECK_OP (0, "Invalid operand to binary operator");
3306 CHECK_OP (1, "Invalid operand to binary operator");
3318 /* Verify STMT, return true if STMT is not in GIMPLE form.
3319 TODO: Implement type checking. */
3322 verify_stmt (tree stmt
, bool last_in_block
)
3326 if (!is_gimple_stmt (stmt
))
3328 error ("Is not a valid GIMPLE statement.");
3332 addr
= walk_tree (&stmt
, verify_expr
, NULL
, NULL
);
3335 debug_generic_stmt (addr
);
3339 /* If the statement is marked as part of an EH region, then it is
3340 expected that the statement could throw. Verify that when we
3341 have optimizations that simplify statements such that we prove
3342 that they cannot throw, that we update other data structures
3344 if (lookup_stmt_eh_region (stmt
) >= 0)
3346 if (!tree_could_throw_p (stmt
))
3348 error ("Statement marked for throw, but doesn't.");
3351 if (!last_in_block
&& tree_can_throw_internal (stmt
))
3353 error ("Statement marked for throw in middle of block.");
3361 debug_generic_stmt (stmt
);
3366 /* Return true when the T can be shared. */
3369 tree_node_can_be_shared (tree t
)
3371 if (TYPE_P (t
) || DECL_P (t
)
3372 /* We check for constants explicitly since they are not considered
3373 gimple invariants if they overflowed. */
3374 || TREE_CODE_CLASS (TREE_CODE (t
)) == 'c'
3375 || is_gimple_min_invariant (t
)
3376 || TREE_CODE (t
) == SSA_NAME
)
3379 while (((TREE_CODE (t
) == ARRAY_REF
|| TREE_CODE (t
) == ARRAY_RANGE_REF
)
3380 /* We check for constants explicitly since they are not considered
3381 gimple invariants if they overflowed. */
3382 && (TREE_CODE_CLASS (TREE_CODE (TREE_OPERAND (t
, 1))) == 'c'
3383 || is_gimple_min_invariant (TREE_OPERAND (t
, 1))))
3384 || (TREE_CODE (t
) == COMPONENT_REF
3385 || TREE_CODE (t
) == REALPART_EXPR
3386 || TREE_CODE (t
) == IMAGPART_EXPR
))
3387 t
= TREE_OPERAND (t
, 0);
3396 /* Called via walk_trees. Verify tree sharing. */
3399 verify_node_sharing (tree
* tp
, int *walk_subtrees
, void *data
)
3401 htab_t htab
= (htab_t
) data
;
3404 if (tree_node_can_be_shared (*tp
))
3406 *walk_subtrees
= false;
3410 slot
= htab_find_slot (htab
, *tp
, INSERT
);
3419 /* Verify the GIMPLE statement chain. */
3425 block_stmt_iterator bsi
;
3430 timevar_push (TV_TREE_STMT_VERIFY
);
3431 htab
= htab_create (37, htab_hash_pointer
, htab_eq_pointer
, NULL
);
3438 for (phi
= phi_nodes (bb
); phi
; phi
= PHI_CHAIN (phi
))
3440 int phi_num_args
= PHI_NUM_ARGS (phi
);
3442 for (i
= 0; i
< phi_num_args
; i
++)
3444 tree t
= PHI_ARG_DEF (phi
, i
);
3447 /* Addressable variables do have SSA_NAMEs but they
3448 are not considered gimple values. */
3449 if (TREE_CODE (t
) != SSA_NAME
3450 && TREE_CODE (t
) != FUNCTION_DECL
3451 && !is_gimple_val (t
))
3453 error ("PHI def is not a GIMPLE value");
3454 debug_generic_stmt (phi
);
3455 debug_generic_stmt (t
);
3459 addr
= walk_tree (&t
, verify_expr
, NULL
, NULL
);
3462 debug_generic_stmt (addr
);
3466 addr
= walk_tree (&t
, verify_node_sharing
, htab
, NULL
);
3469 error ("Incorrect sharing of tree nodes");
3470 debug_generic_stmt (phi
);
3471 debug_generic_stmt (addr
);
3477 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); )
3479 tree stmt
= bsi_stmt (bsi
);
3481 err
|= verify_stmt (stmt
, bsi_end_p (bsi
));
3482 addr
= walk_tree (&stmt
, verify_node_sharing
, htab
, NULL
);
3485 error ("Incorrect sharing of tree nodes");
3486 debug_generic_stmt (stmt
);
3487 debug_generic_stmt (addr
);
3494 internal_error ("verify_stmts failed.");
3497 timevar_pop (TV_TREE_STMT_VERIFY
);
3501 /* Verifies that the flow information is OK. */
3504 tree_verify_flow_info (void)
3508 block_stmt_iterator bsi
;
3512 if (ENTRY_BLOCK_PTR
->stmt_list
)
3514 error ("ENTRY_BLOCK has a statement list associated with it\n");
3518 if (EXIT_BLOCK_PTR
->stmt_list
)
3520 error ("EXIT_BLOCK has a statement list associated with it\n");
3524 for (e
= EXIT_BLOCK_PTR
->pred
; e
; e
= e
->pred_next
)
3525 if (e
->flags
& EDGE_FALLTHRU
)
3527 error ("Fallthru to exit from bb %d\n", e
->src
->index
);
3533 bool found_ctrl_stmt
= false;
3535 /* Skip labels on the start of basic block. */
3536 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
3538 if (TREE_CODE (bsi_stmt (bsi
)) != LABEL_EXPR
)
3541 if (label_to_block (LABEL_EXPR_LABEL (bsi_stmt (bsi
))) != bb
)
3543 error ("Label %s to block does not match in bb %d\n",
3544 IDENTIFIER_POINTER (DECL_NAME (bsi_stmt (bsi
))),
3549 if (decl_function_context (LABEL_EXPR_LABEL (bsi_stmt (bsi
)))
3550 != current_function_decl
)
3552 error ("Label %s has incorrect context in bb %d\n",
3553 IDENTIFIER_POINTER (DECL_NAME (bsi_stmt (bsi
))),
3559 /* Verify that body of basic block BB is free of control flow. */
3560 for (; !bsi_end_p (bsi
); bsi_next (&bsi
))
3562 tree stmt
= bsi_stmt (bsi
);
3564 if (found_ctrl_stmt
)
3566 error ("Control flow in the middle of basic block %d\n",
3571 if (stmt_ends_bb_p (stmt
))
3572 found_ctrl_stmt
= true;
3574 if (TREE_CODE (stmt
) == LABEL_EXPR
)
3576 error ("Label %s in the middle of basic block %d\n",
3577 IDENTIFIER_POINTER (DECL_NAME (stmt
)),
3582 bsi
= bsi_last (bb
);
3583 if (bsi_end_p (bsi
))
3586 stmt
= bsi_stmt (bsi
);
3588 if (is_ctrl_stmt (stmt
))
3590 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
3591 if (e
->flags
& EDGE_FALLTHRU
)
3593 error ("Fallthru edge after a control statement in bb %d \n",
3599 switch (TREE_CODE (stmt
))
3605 if (TREE_CODE (COND_EXPR_THEN (stmt
)) != GOTO_EXPR
3606 || TREE_CODE (COND_EXPR_ELSE (stmt
)) != GOTO_EXPR
)
3608 error ("Structured COND_EXPR at the end of bb %d\n", bb
->index
);
3612 extract_true_false_edges_from_block (bb
, &true_edge
, &false_edge
);
3614 if (!true_edge
|| !false_edge
3615 || !(true_edge
->flags
& EDGE_TRUE_VALUE
)
3616 || !(false_edge
->flags
& EDGE_FALSE_VALUE
)
3617 || (true_edge
->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
))
3618 || (false_edge
->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
))
3619 || bb
->succ
->succ_next
->succ_next
)
3621 error ("Wrong outgoing edge flags at end of bb %d\n",
3626 if (!has_label_p (true_edge
->dest
,
3627 GOTO_DESTINATION (COND_EXPR_THEN (stmt
))))
3629 error ("`then' label does not match edge at end of bb %d\n",
3634 if (!has_label_p (false_edge
->dest
,
3635 GOTO_DESTINATION (COND_EXPR_ELSE (stmt
))))
3637 error ("`else' label does not match edge at end of bb %d\n",
3645 if (simple_goto_p (stmt
))
3647 error ("Explicit goto at end of bb %d\n", bb
->index
);
3652 /* FIXME. We should double check that the labels in the
3653 destination blocks have their address taken. */
3654 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
3655 if ((e
->flags
& (EDGE_FALLTHRU
| EDGE_TRUE_VALUE
3656 | EDGE_FALSE_VALUE
))
3657 || !(e
->flags
& EDGE_ABNORMAL
))
3659 error ("Wrong outgoing edge flags at end of bb %d\n",
3667 if (!bb
->succ
|| bb
->succ
->succ_next
3668 || (bb
->succ
->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
3669 | EDGE_TRUE_VALUE
| EDGE_FALSE_VALUE
)))
3671 error ("Wrong outgoing edge flags at end of bb %d\n", bb
->index
);
3674 if (bb
->succ
->dest
!= EXIT_BLOCK_PTR
)
3676 error ("Return edge does not point to exit in bb %d\n",
3689 vec
= SWITCH_LABELS (stmt
);
3690 n
= TREE_VEC_LENGTH (vec
);
3692 /* Mark all the destination basic blocks. */
3693 for (i
= 0; i
< n
; ++i
)
3695 tree lab
= CASE_LABEL (TREE_VEC_ELT (vec
, i
));
3696 basic_block label_bb
= label_to_block (lab
);
3698 if (label_bb
->aux
&& label_bb
->aux
!= (void *)1)
3700 label_bb
->aux
= (void *)1;
3703 /* Verify that the case labels are sorted. */
3704 prev
= TREE_VEC_ELT (vec
, 0);
3705 for (i
= 1; i
< n
- 1; ++i
)
3707 tree c
= TREE_VEC_ELT (vec
, i
);
3710 error ("Found default case not at end of case vector");
3714 if (! tree_int_cst_lt (CASE_LOW (prev
), CASE_LOW (c
)))
3716 error ("Case labels not sorted:\n ");
3717 print_generic_expr (stderr
, prev
, 0);
3718 fprintf (stderr
," is greater than ");
3719 print_generic_expr (stderr
, c
, 0);
3720 fprintf (stderr
," but comes before it.\n");
3725 if (CASE_LOW (TREE_VEC_ELT (vec
, n
- 1)))
3727 error ("No default case found at end of case vector");
3731 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
3735 error ("Extra outgoing edge %d->%d\n",
3736 bb
->index
, e
->dest
->index
);
3739 e
->dest
->aux
= (void *)2;
3740 if ((e
->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
3741 | EDGE_TRUE_VALUE
| EDGE_FALSE_VALUE
)))
3743 error ("Wrong outgoing edge flags at end of bb %d\n",
3749 /* Check that we have all of them. */
3750 for (i
= 0; i
< n
; ++i
)
3752 tree lab
= CASE_LABEL (TREE_VEC_ELT (vec
, i
));
3753 basic_block label_bb
= label_to_block (lab
);
3755 if (label_bb
->aux
!= (void *)2)
3757 error ("Missing edge %i->%i\n",
3758 bb
->index
, label_bb
->index
);
3763 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
3764 e
->dest
->aux
= (void *)0;
3771 if (dom_computed
[CDI_DOMINATORS
] >= DOM_NO_FAST_QUERY
)
3772 verify_dominators (CDI_DOMINATORS
);
3778 /* Updates phi nodes after creating forwarder block joined
3779 by edge FALLTHRU. */
3782 tree_make_forwarder_block (edge fallthru
)
3785 basic_block dummy
, bb
;
3786 tree phi
, new_phi
, var
, prev
, next
;
3788 dummy
= fallthru
->src
;
3789 bb
= fallthru
->dest
;
3791 if (!bb
->pred
->pred_next
)
3794 /* If we redirected a branch we must create new phi nodes at the
3796 for (phi
= phi_nodes (dummy
); phi
; phi
= PHI_CHAIN (phi
))
3798 var
= PHI_RESULT (phi
);
3799 new_phi
= create_phi_node (var
, bb
);
3800 SSA_NAME_DEF_STMT (var
) = new_phi
;
3801 SET_PHI_RESULT (phi
, make_ssa_name (SSA_NAME_VAR (var
), phi
));
3802 add_phi_arg (&new_phi
, PHI_RESULT (phi
), fallthru
);
3805 /* Ensure that the PHI node chain is in the same order. */
3807 for (phi
= phi_nodes (bb
); phi
; phi
= next
)
3809 next
= PHI_CHAIN (phi
);
3810 PHI_CHAIN (phi
) = prev
;
3813 set_phi_nodes (bb
, prev
);
3815 /* Add the arguments we have stored on edges. */
3816 for (e
= bb
->pred
; e
; e
= e
->pred_next
)
3821 for (phi
= phi_nodes (bb
), var
= PENDING_STMT (e
);
3823 phi
= PHI_CHAIN (phi
), var
= TREE_CHAIN (var
))
3824 add_phi_arg (&phi
, TREE_VALUE (var
), e
);
3826 PENDING_STMT (e
) = NULL
;
3831 /* Return true if basic block BB does nothing except pass control
3832 flow to another block and that we can safely insert a label at
3833 the start of the successor block. */
3836 tree_forwarder_block_p (basic_block bb
)
3838 block_stmt_iterator bsi
;
3841 /* If we have already determined that this block is not forwardable,
3842 then no further checks are necessary. */
3843 if (! bb_ann (bb
)->forwardable
)
3846 /* BB must have a single outgoing normal edge. Otherwise it can not be
3847 a forwarder block. */
3849 || bb
->succ
->succ_next
3850 || bb
->succ
->dest
== EXIT_BLOCK_PTR
3851 || (bb
->succ
->flags
& EDGE_ABNORMAL
)
3852 || bb
== ENTRY_BLOCK_PTR
)
3854 bb_ann (bb
)->forwardable
= 0;
3858 /* Successors of the entry block are not forwarders. */
3859 for (e
= ENTRY_BLOCK_PTR
->succ
; e
; e
= e
->succ_next
)
3862 bb_ann (bb
)->forwardable
= 0;
3866 /* BB can not have any PHI nodes. This could potentially be relaxed
3867 early in compilation if we re-rewrote the variables appearing in
3868 any PHI nodes in forwarder blocks. */
3871 bb_ann (bb
)->forwardable
= 0;
3875 /* Now walk through the statements. We can ignore labels, anything else
3876 means this is not a forwarder block. */
3877 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
3879 tree stmt
= bsi_stmt (bsi
);
3881 switch (TREE_CODE (stmt
))
3884 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt
)))
3889 bb_ann (bb
)->forwardable
= 0;
3898 /* Thread jumps over empty statements.
3900 This code should _not_ thread over obviously equivalent conditions
3901 as that requires nontrivial updates to the SSA graph. */
3906 edge e
, next
, last
, old
;
3907 basic_block bb
, dest
, tmp
;
3910 bool retval
= false;
3913 bb_ann (bb
)->forwardable
= 1;
3915 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
, EXIT_BLOCK_PTR
, next_bb
)
3917 /* Don't waste time on unreachable blocks. */
3921 /* Nor on forwarders. */
3922 if (tree_forwarder_block_p (bb
))
3925 /* This block is now part of a forwarding path, mark it as not
3926 forwardable so that we can detect loops. This bit will be
3928 bb_ann (bb
)->forwardable
= 0;
3930 /* Examine each of our block's successors to see if it is
3932 for (e
= bb
->succ
; e
; e
= next
)
3934 next
= e
->succ_next
;
3936 /* If the edge is abnormal or its destination is not
3937 forwardable, then there's nothing to do. */
3938 if ((e
->flags
& EDGE_ABNORMAL
)
3939 || !tree_forwarder_block_p (e
->dest
))
3942 /* Now walk through as many forwarder block as possible to
3943 find the ultimate destination we want to thread our jump
3945 last
= e
->dest
->succ
;
3946 bb_ann (e
->dest
)->forwardable
= 0;
3947 for (dest
= e
->dest
->succ
->dest
;
3948 tree_forwarder_block_p (dest
);
3950 dest
= dest
->succ
->dest
)
3952 /* An infinite loop detected. We redirect the edge anyway, so
3953 that the loop is shrunk into single basic block. */
3954 if (!bb_ann (dest
)->forwardable
)
3957 if (dest
->succ
->dest
== EXIT_BLOCK_PTR
)
3960 bb_ann (dest
)->forwardable
= 0;
3963 /* Reset the forwardable marks to 1. */
3966 tmp
= tmp
->succ
->dest
)
3967 bb_ann (tmp
)->forwardable
= 1;
3969 if (dest
== e
->dest
)
3972 old
= find_edge (bb
, dest
);
3975 /* If there already is an edge, check whether the values
3976 in phi nodes differ. */
3977 if (!phi_alternatives_equal (dest
, last
, old
))
3979 /* The previous block is forwarder. Redirect our jump
3980 to that target instead since we know it has no PHI
3981 nodes that will need updating. */
3984 /* That might mean that no forwarding at all is possible. */
3985 if (dest
== e
->dest
)
3988 old
= find_edge (bb
, dest
);
3992 /* Perform the redirection. */
3994 e
= redirect_edge_and_branch (e
, dest
);
3996 /* TODO -- updating dominators in this case is simple. */
3997 free_dominance_info (CDI_DOMINATORS
);
4001 /* Update PHI nodes. We know that the new argument should
4002 have the same value as the argument associated with LAST.
4003 Otherwise we would have changed our target block above. */
4004 for (phi
= phi_nodes (dest
); phi
; phi
= PHI_CHAIN (phi
))
4006 arg
= phi_arg_from_edge (phi
, last
);
4009 add_phi_arg (&phi
, PHI_ARG_DEF (phi
, arg
), e
);
4014 /* Reset the forwardable bit on our block since it's no longer in
4015 a forwarding chain path. */
4016 bb_ann (bb
)->forwardable
= 1;
4023 /* Return a non-special label in the head of basic block BLOCK.
4024 Create one if it doesn't exist. */
4027 tree_block_label (basic_block bb
)
4029 block_stmt_iterator i
, s
= bsi_start (bb
);
4033 for (i
= s
; !bsi_end_p (i
); first
= false, bsi_next (&i
))
4035 stmt
= bsi_stmt (i
);
4036 if (TREE_CODE (stmt
) != LABEL_EXPR
)
4038 label
= LABEL_EXPR_LABEL (stmt
);
4039 if (!DECL_NONLOCAL (label
))
4042 bsi_move_before (&i
, &s
);
4047 label
= create_artificial_label ();
4048 stmt
= build1 (LABEL_EXPR
, void_type_node
, label
);
4049 bsi_insert_before (&s
, stmt
, BSI_NEW_STMT
);
4054 /* Attempt to perform edge redirection by replacing a possibly complex
4055 jump instruction by a goto or by removing the jump completely.
4056 This can apply only if all edges now point to the same block. The
4057 parameters and return values are equivalent to
4058 redirect_edge_and_branch. */
4061 tree_try_redirect_by_replacing_jump (edge e
, basic_block target
)
4063 basic_block src
= e
->src
;
4065 block_stmt_iterator b
;
4068 /* Verify that all targets will be TARGET. */
4069 for (tmp
= src
->succ
; tmp
; tmp
= tmp
->succ_next
)
4070 if (tmp
->dest
!= target
&& tmp
!= e
)
4079 stmt
= bsi_stmt (b
);
4081 if (TREE_CODE (stmt
) == COND_EXPR
4082 || TREE_CODE (stmt
) == SWITCH_EXPR
)
4085 e
= ssa_redirect_edge (e
, target
);
4086 e
->flags
= EDGE_FALLTHRU
;
4094 /* Redirect E to DEST. Return NULL on failure. Otherwise, return the
4095 edge representing the redirected branch. */
4098 tree_redirect_edge_and_branch (edge e
, basic_block dest
)
4100 basic_block bb
= e
->src
;
4101 block_stmt_iterator bsi
;
4105 if (e
->flags
& (EDGE_ABNORMAL_CALL
| EDGE_EH
))
4108 if (e
->src
!= ENTRY_BLOCK_PTR
4109 && (ret
= tree_try_redirect_by_replacing_jump (e
, dest
)))
4112 if (e
->dest
== dest
)
4115 label
= tree_block_label (dest
);
4117 bsi
= bsi_last (bb
);
4118 stmt
= bsi_end_p (bsi
) ? NULL
: bsi_stmt (bsi
);
4120 switch (stmt
? TREE_CODE (stmt
) : ERROR_MARK
)
4123 stmt
= (e
->flags
& EDGE_TRUE_VALUE
4124 ? COND_EXPR_THEN (stmt
)
4125 : COND_EXPR_ELSE (stmt
));
4126 GOTO_DESTINATION (stmt
) = label
;
4130 /* No non-abnormal edges should lead from a non-simple goto, and
4131 simple ones should be represented implicitly. */
4136 tree vec
= SWITCH_LABELS (stmt
);
4137 size_t i
, n
= TREE_VEC_LENGTH (vec
);
4139 for (i
= 0; i
< n
; ++i
)
4141 tree elt
= TREE_VEC_ELT (vec
, i
);
4142 if (label_to_block (CASE_LABEL (elt
)) == e
->dest
)
4143 CASE_LABEL (elt
) = label
;
4150 e
->flags
|= EDGE_FALLTHRU
;
4154 /* Otherwise it must be a fallthru edge, and we don't need to
4155 do anything besides redirecting it. */
4156 if (!(e
->flags
& EDGE_FALLTHRU
))
4161 /* Update/insert PHI nodes as necessary. */
4163 /* Now update the edges in the CFG. */
4164 e
= ssa_redirect_edge (e
, dest
);
4170 /* Simple wrapper, as we can always redirect fallthru edges. */
4173 tree_redirect_edge_and_branch_force (edge e
, basic_block dest
)
4175 e
= tree_redirect_edge_and_branch (e
, dest
);
4183 /* Splits basic block BB after statement STMT (but at least after the
4184 labels). If STMT is NULL, BB is split just after the labels. */
4187 tree_split_block (basic_block bb
, void *stmt
)
4189 block_stmt_iterator bsi
, bsi_tgt
;
4194 new_bb
= create_empty_bb (bb
);
4196 /* Redirect the outgoing edges. */
4197 new_bb
->succ
= bb
->succ
;
4199 for (e
= new_bb
->succ
; e
; e
= e
->succ_next
)
4202 if (stmt
&& TREE_CODE ((tree
) stmt
) == LABEL_EXPR
)
4205 /* Move everything from BSI to the new basic block. */
4206 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
4208 act
= bsi_stmt (bsi
);
4209 if (TREE_CODE (act
) == LABEL_EXPR
)
4222 bsi_tgt
= bsi_start (new_bb
);
4223 while (!bsi_end_p (bsi
))
4225 act
= bsi_stmt (bsi
);
4227 bsi_insert_after (&bsi_tgt
, act
, BSI_NEW_STMT
);
4234 /* Moves basic block BB after block AFTER. */
4237 tree_move_block_after (basic_block bb
, basic_block after
)
4239 if (bb
->prev_bb
== after
)
4243 link_block (bb
, after
);
4249 /* Return true if basic_block can be duplicated. */
4252 tree_can_duplicate_bb_p (basic_block bb ATTRIBUTE_UNUSED
)
4258 /* Create a duplicate of the basic block BB. NOTE: This does not
4259 preserve SSA form. */
4262 tree_duplicate_bb (basic_block bb
)
4265 block_stmt_iterator bsi
, bsi_tgt
;
4267 new_bb
= create_empty_bb (EXIT_BLOCK_PTR
->prev_bb
);
4268 bsi_tgt
= bsi_start (new_bb
);
4269 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
4271 tree stmt
= bsi_stmt (bsi
);
4274 if (TREE_CODE (stmt
) == LABEL_EXPR
)
4277 copy
= unshare_expr (stmt
);
4279 /* Copy also the virtual operands. */
4280 get_stmt_ann (copy
);
4281 copy_virtual_operands (copy
, stmt
);
4283 bsi_insert_after (&bsi_tgt
, copy
, BSI_NEW_STMT
);
4290 /* Dump FUNCTION_DECL FN to file FILE using FLAGS (see TDF_* in tree.h) */
4293 dump_function_to_file (tree fn
, FILE *file
, int flags
)
4295 tree arg
, vars
, var
;
4296 bool ignore_topmost_bind
= false, any_var
= false;
4300 fprintf (file
, "%s (", lang_hooks
.decl_printable_name (fn
, 2));
4302 arg
= DECL_ARGUMENTS (fn
);
4305 print_generic_expr (file
, arg
, dump_flags
);
4306 if (TREE_CHAIN (arg
))
4307 fprintf (file
, ", ");
4308 arg
= TREE_CHAIN (arg
);
4310 fprintf (file
, ")\n");
4312 if (flags
& TDF_RAW
)
4314 dump_node (fn
, TDF_SLIM
| flags
, file
);
4318 /* When GIMPLE is lowered, the variables are no longer available in
4319 BIND_EXPRs, so display them separately. */
4320 if (cfun
&& cfun
->unexpanded_var_list
)
4322 ignore_topmost_bind
= true;
4324 fprintf (file
, "{\n");
4325 for (vars
= cfun
->unexpanded_var_list
; vars
; vars
= TREE_CHAIN (vars
))
4327 var
= TREE_VALUE (vars
);
4329 print_generic_decl (file
, var
, flags
);
4330 fprintf (file
, "\n");
4336 if (basic_block_info
)
4338 /* Make a CFG based dump. */
4339 if (!ignore_topmost_bind
)
4340 fprintf (file
, "{\n");
4342 if (any_var
&& n_basic_blocks
)
4343 fprintf (file
, "\n");
4346 dump_generic_bb (file
, bb
, 2, flags
);
4348 fprintf (file
, "}\n");
4354 /* Make a tree based dump. */
4355 chain
= DECL_SAVED_TREE (fn
);
4357 if (TREE_CODE (chain
) == BIND_EXPR
)
4359 if (ignore_topmost_bind
)
4361 chain
= BIND_EXPR_BODY (chain
);
4369 if (!ignore_topmost_bind
)
4370 fprintf (file
, "{\n");
4375 fprintf (file
, "\n");
4377 print_generic_stmt_indented (file
, chain
, flags
, indent
);
4378 if (ignore_topmost_bind
)
4379 fprintf (file
, "}\n");
4382 fprintf (file
, "\n\n");
4386 /* Pretty print of the loops intermediate representation. */
4387 static void print_loop (FILE *, struct loop
*, int);
4388 static void print_pred_bbs (FILE *, edge
);
4389 static void print_succ_bbs (FILE *, edge
);
4392 /* Print the predecessors indexes of edge E on FILE. */
4395 print_pred_bbs (FILE *file
, edge e
)
4400 else if (e
->pred_next
== NULL
)
4401 fprintf (file
, "bb_%d", e
->src
->index
);
4405 fprintf (file
, "bb_%d, ", e
->src
->index
);
4406 print_pred_bbs (file
, e
->pred_next
);
4411 /* Print the successors indexes of edge E on FILE. */
4414 print_succ_bbs (FILE *file
, edge e
)
4418 else if (e
->succ_next
== NULL
)
4419 fprintf (file
, "bb_%d", e
->dest
->index
);
4422 fprintf (file
, "bb_%d, ", e
->dest
->index
);
4423 print_succ_bbs (file
, e
->succ_next
);
4428 /* Pretty print LOOP on FILE, indented INDENT spaces. */
4431 print_loop (FILE *file
, struct loop
*loop
, int indent
)
4439 s_indent
= (char *) alloca ((size_t) indent
+ 1);
4440 memset ((void *) s_indent
, ' ', (size_t) indent
);
4441 s_indent
[indent
] = '\0';
4443 /* Print the loop's header. */
4444 fprintf (file
, "%sloop_%d\n", s_indent
, loop
->num
);
4446 /* Print the loop's body. */
4447 fprintf (file
, "%s{\n", s_indent
);
4449 if (bb
->loop_father
== loop
)
4451 /* Print the basic_block's header. */
4452 fprintf (file
, "%s bb_%d (preds = {", s_indent
, bb
->index
);
4453 print_pred_bbs (file
, bb
->pred
);
4454 fprintf (file
, "}, succs = {");
4455 print_succ_bbs (file
, bb
->succ
);
4456 fprintf (file
, "})\n");
4458 /* Print the basic_block's body. */
4459 fprintf (file
, "%s {\n", s_indent
);
4460 tree_dump_bb (bb
, file
, indent
+ 4);
4461 fprintf (file
, "%s }\n", s_indent
);
4464 print_loop (file
, loop
->inner
, indent
+ 2);
4465 fprintf (file
, "%s}\n", s_indent
);
4466 print_loop (file
, loop
->next
, indent
);
4470 /* Follow a CFG edge from the entry point of the program, and on entry
4471 of a loop, pretty print the loop structure on FILE. */
4474 print_loop_ir (FILE *file
)
4478 bb
= BASIC_BLOCK (0);
4479 if (bb
&& bb
->loop_father
)
4480 print_loop (file
, bb
->loop_father
, 0);
4484 /* Debugging loops structure at tree level. */
4487 debug_loop_ir (void)
4489 print_loop_ir (stderr
);
4493 /* Return true if BB ends with a call, possibly followed by some
4494 instructions that must stay with the call. Return false,
4498 tree_block_ends_with_call_p (basic_block bb
)
4500 block_stmt_iterator bsi
= bsi_last (bb
);
4501 return get_call_expr_in (bsi_stmt (bsi
)) != NULL
;
4505 /* Return true if BB ends with a conditional branch. Return false,
4509 tree_block_ends_with_condjump_p (basic_block bb
)
4511 tree stmt
= tsi_stmt (bsi_last (bb
).tsi
);
4512 return (TREE_CODE (stmt
) == COND_EXPR
);
4516 /* Return true if we need to add fake edge to exit at statement T.
4517 Helper function for tree_flow_call_edges_add. */
4520 need_fake_edge_p (tree t
)
4524 /* NORETURN and LONGJMP calls already have an edge to exit.
4525 CONST, PURE and ALWAYS_RETURN calls do not need one.
4526 We don't currently check for CONST and PURE here, although
4527 it would be a good idea, because those attributes are
4528 figured out from the RTL in mark_constant_function, and
4529 the counter incrementation code from -fprofile-arcs
4530 leads to different results from -fbranch-probabilities. */
4531 call
= get_call_expr_in (t
);
4533 && !(call_expr_flags (call
) &
4534 (ECF_NORETURN
| ECF_LONGJMP
| ECF_ALWAYS_RETURN
)))
4537 if (TREE_CODE (t
) == ASM_EXPR
4538 && (ASM_VOLATILE_P (t
) || ASM_INPUT_P (t
)))
4545 /* Add fake edges to the function exit for any non constant and non
4546 noreturn calls, volatile inline assembly in the bitmap of blocks
4547 specified by BLOCKS or to the whole CFG if BLOCKS is zero. Return
4548 the number of blocks that were split.
4550 The goal is to expose cases in which entering a basic block does
4551 not imply that all subsequent instructions must be executed. */
4554 tree_flow_call_edges_add (sbitmap blocks
)
4557 int blocks_split
= 0;
4558 int last_bb
= last_basic_block
;
4559 bool check_last_block
= false;
4561 if (n_basic_blocks
== 0)
4565 check_last_block
= true;
4567 check_last_block
= TEST_BIT (blocks
, EXIT_BLOCK_PTR
->prev_bb
->index
);
4569 /* In the last basic block, before epilogue generation, there will be
4570 a fallthru edge to EXIT. Special care is required if the last insn
4571 of the last basic block is a call because make_edge folds duplicate
4572 edges, which would result in the fallthru edge also being marked
4573 fake, which would result in the fallthru edge being removed by
4574 remove_fake_edges, which would result in an invalid CFG.
4576 Moreover, we can't elide the outgoing fake edge, since the block
4577 profiler needs to take this into account in order to solve the minimal
4578 spanning tree in the case that the call doesn't return.
4580 Handle this by adding a dummy instruction in a new last basic block. */
4581 if (check_last_block
)
4583 basic_block bb
= EXIT_BLOCK_PTR
->prev_bb
;
4584 block_stmt_iterator bsi
= bsi_last (bb
);
4586 if (!bsi_end_p (bsi
))
4589 if (need_fake_edge_p (t
))
4593 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
4594 if (e
->dest
== EXIT_BLOCK_PTR
)
4596 bsi_insert_on_edge (e
, build_empty_stmt ());
4597 bsi_commit_edge_inserts ((int *)NULL
);
4603 /* Now add fake edges to the function exit for any non constant
4604 calls since there is no way that we can determine if they will
4606 for (i
= 0; i
< last_bb
; i
++)
4608 basic_block bb
= BASIC_BLOCK (i
);
4609 block_stmt_iterator bsi
;
4610 tree stmt
, last_stmt
;
4615 if (blocks
&& !TEST_BIT (blocks
, i
))
4618 bsi
= bsi_last (bb
);
4619 if (!bsi_end_p (bsi
))
4621 last_stmt
= bsi_stmt (bsi
);
4624 stmt
= bsi_stmt (bsi
);
4625 if (need_fake_edge_p (stmt
))
4628 /* The handling above of the final block before the
4629 epilogue should be enough to verify that there is
4630 no edge to the exit block in CFG already.
4631 Calling make_edge in such case would cause us to
4632 mark that edge as fake and remove it later. */
4633 #ifdef ENABLE_CHECKING
4634 if (stmt
== last_stmt
)
4635 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
4636 if (e
->dest
== EXIT_BLOCK_PTR
)
4640 /* Note that the following may create a new basic block
4641 and renumber the existing basic blocks. */
4642 if (stmt
!= last_stmt
)
4644 e
= split_block (bb
, stmt
);
4648 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
4652 while (!bsi_end_p (bsi
));
4657 verify_flow_info ();
4659 return blocks_split
;
4663 tree_purge_dead_eh_edges (basic_block bb
)
4665 bool changed
= false;
4667 tree stmt
= last_stmt (bb
);
4669 if (stmt
&& tree_can_throw_internal (stmt
))
4672 for (e
= bb
->succ
; e
; e
= next
)
4674 next
= e
->succ_next
;
4675 if (e
->flags
& EDGE_EH
)
4677 ssa_remove_edge (e
);
4686 tree_purge_all_dead_eh_edges (bitmap blocks
)
4688 bool changed
= false;
4691 EXECUTE_IF_SET_IN_BITMAP (blocks
, 0, i
,
4692 { changed
|= tree_purge_dead_eh_edges (BASIC_BLOCK (i
)); });
4697 struct cfg_hooks tree_cfg_hooks
= {
4699 tree_verify_flow_info
,
4700 tree_dump_bb
, /* dump_bb */
4701 create_bb
, /* create_basic_block */
4702 tree_redirect_edge_and_branch
,/* redirect_edge_and_branch */
4703 tree_redirect_edge_and_branch_force
,/* redirect_edge_and_branch_force */
4704 remove_bb
, /* delete_basic_block */
4705 tree_split_block
, /* split_block */
4706 tree_move_block_after
, /* move_block_after */
4707 tree_can_merge_blocks_p
, /* can_merge_blocks_p */
4708 tree_merge_blocks
, /* merge_blocks */
4709 tree_predict_edge
, /* predict_edge */
4710 tree_predicted_by_p
, /* predicted_by_p */
4711 tree_can_duplicate_bb_p
, /* can_duplicate_block_p */
4712 tree_duplicate_bb
, /* duplicate_block */
4713 tree_split_edge
, /* split_edge */
4714 tree_make_forwarder_block
, /* make_forward_block */
4715 NULL
, /* tidy_fallthru_edge */
4716 tree_block_ends_with_call_p
, /* block_ends_with_call_p */
4717 tree_block_ends_with_condjump_p
, /* block_ends_with_condjump_p */
4718 tree_flow_call_edges_add
/* flow_call_edges_add */
4722 /* Split all critical edges. */
4725 split_critical_edges (void)
4732 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
4733 if (EDGE_CRITICAL_P (e
) && !(e
->flags
& EDGE_ABNORMAL
))
4740 struct tree_opt_pass pass_split_crit_edges
=
4742 "crited", /* name */
4744 split_critical_edges
, /* execute */
4747 0, /* static_pass_number */
4748 TV_TREE_SPLIT_EDGES
, /* tv_id */
4749 PROP_cfg
, /* properties required */
4750 PROP_no_crit_edges
, /* properties_provided */
4751 0, /* properties_destroyed */
4752 0, /* todo_flags_start */
4753 TODO_dump_func
, /* todo_flags_finish */
4756 /* Emit return warnings. */
4759 execute_warn_function_return (void)
4761 #ifdef USE_MAPPED_LOCATION
4762 source_location location
;
4769 if (warn_missing_noreturn
4770 && !TREE_THIS_VOLATILE (cfun
->decl
)
4771 && EXIT_BLOCK_PTR
->pred
== NULL
4772 && !lang_hooks
.function
.missing_noreturn_ok_p (cfun
->decl
))
4773 warning ("%Jfunction might be possible candidate for attribute `noreturn'",
4776 /* If we have a path to EXIT, then we do return. */
4777 if (TREE_THIS_VOLATILE (cfun
->decl
)
4778 && EXIT_BLOCK_PTR
->pred
!= NULL
)
4780 #ifdef USE_MAPPED_LOCATION
4781 location
= UNKNOWN_LOCATION
;
4785 for (e
= EXIT_BLOCK_PTR
->pred
; e
; e
= e
->pred_next
)
4787 last
= last_stmt (e
->src
);
4788 if (TREE_CODE (last
) == RETURN_EXPR
4789 #ifdef USE_MAPPED_LOCATION
4790 && (location
= EXPR_LOCATION (last
)) != UNKNOWN_LOCATION
)
4792 && (locus
= EXPR_LOCUS (last
)) != NULL
)
4796 #ifdef USE_MAPPED_LOCATION
4797 if (location
== UNKNOWN_LOCATION
)
4798 location
= cfun
->function_end_locus
;
4799 warning ("%H`noreturn' function does return", &location
);
4802 locus
= &cfun
->function_end_locus
;
4803 warning ("%H`noreturn' function does return", locus
);
4807 /* If we see "return;" in some basic block, then we do reach the end
4808 without returning a value. */
4809 else if (warn_return_type
4810 && EXIT_BLOCK_PTR
->pred
!= NULL
4811 && !VOID_TYPE_P (TREE_TYPE (TREE_TYPE (cfun
->decl
))))
4813 for (e
= EXIT_BLOCK_PTR
->pred
; e
; e
= e
->pred_next
)
4815 tree last
= last_stmt (e
->src
);
4816 if (TREE_CODE (last
) == RETURN_EXPR
4817 && TREE_OPERAND (last
, 0) == NULL
)
4819 #ifdef USE_MAPPED_LOCATION
4820 location
= EXPR_LOCATION (last
);
4821 if (location
== UNKNOWN_LOCATION
)
4822 location
= cfun
->function_end_locus
;
4823 warning ("%Hcontrol reaches end of non-void function", &location
);
4825 locus
= EXPR_LOCUS (last
);
4827 locus
= &cfun
->function_end_locus
;
4828 warning ("%Hcontrol reaches end of non-void function", locus
);
4837 /* Given a basic block B which ends with a conditional and has
4838 precisely two successors, determine which of the edges is taken if
4839 the conditional is true and which is taken if the conditional is
4840 false. Set TRUE_EDGE and FALSE_EDGE appropriately. */
4843 extract_true_false_edges_from_block (basic_block b
,
4849 if (e
->flags
& EDGE_TRUE_VALUE
)
4852 *false_edge
= e
->succ_next
;
4857 *true_edge
= e
->succ_next
;
4861 struct tree_opt_pass pass_warn_function_return
=
4865 execute_warn_function_return
, /* execute */
4868 0, /* static_pass_number */
4870 PROP_cfg
, /* properties_required */
4871 0, /* properties_provided */
4872 0, /* properties_destroyed */
4873 0, /* todo_flags_start */
4874 0 /* todo_flags_finish */
4877 #include "gt-tree-cfg.h"