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 void group_case_labels (void);
103 static void cleanup_dead_labels (void);
104 static bool cleanup_control_flow (void);
105 static bool cleanup_control_expr_graph (basic_block
, block_stmt_iterator
);
106 static edge
find_taken_edge_cond_expr (basic_block
, tree
);
107 static edge
find_taken_edge_switch_expr (basic_block
, tree
);
108 static tree
find_case_label_for_value (tree
, tree
);
109 static bool phi_alternatives_equal (basic_block
, edge
, edge
);
112 /*---------------------------------------------------------------------------
114 ---------------------------------------------------------------------------*/
116 /* Entry point to the CFG builder for trees. TP points to the list of
117 statements to be added to the flowgraph. */
120 build_tree_cfg (tree
*tp
)
122 /* Register specific tree functions. */
123 tree_register_cfg_hooks ();
125 /* Initialize rbi_pool. */
128 /* Initialize the basic block array. */
131 last_basic_block
= 0;
132 VARRAY_BB_INIT (basic_block_info
, initial_cfg_capacity
, "basic_block_info");
133 memset ((void *) &cfg_stats
, 0, sizeof (cfg_stats
));
135 /* Build a mapping of labels to their associated blocks. */
136 VARRAY_BB_INIT (label_to_block_map
, initial_cfg_capacity
,
137 "label to block map");
139 ENTRY_BLOCK_PTR
->next_bb
= EXIT_BLOCK_PTR
;
140 EXIT_BLOCK_PTR
->prev_bb
= ENTRY_BLOCK_PTR
;
142 found_computed_goto
= 0;
145 /* Computed gotos are hell to deal with, especially if there are
146 lots of them with a large number of destinations. So we factor
147 them to a common computed goto location before we build the
148 edge list. After we convert back to normal form, we will un-factor
149 the computed gotos since factoring introduces an unwanted jump. */
150 if (found_computed_goto
)
151 factor_computed_gotos ();
153 /* Make sure there is always at least one block, even if its empty. */
154 if (n_basic_blocks
== 0)
155 create_empty_bb (ENTRY_BLOCK_PTR
);
157 create_block_annotation (ENTRY_BLOCK_PTR
);
158 create_block_annotation (EXIT_BLOCK_PTR
);
160 /* Adjust the size of the array. */
161 VARRAY_GROW (basic_block_info
, n_basic_blocks
);
163 /* To speed up statement iterator walks, we first purge dead labels. */
164 cleanup_dead_labels ();
166 /* Group case nodes to reduce the number of edges.
167 We do this after cleaning up dead labels because otherwise we miss
168 a lot of obvious case merging opportunities. */
169 group_case_labels ();
171 /* Create the edges of the flowgraph. */
174 /* Debugging dumps. */
176 /* Write the flowgraph to a VCG file. */
178 int local_dump_flags
;
179 FILE *dump_file
= dump_begin (TDI_vcg
, &local_dump_flags
);
182 tree_cfg2vcg (dump_file
);
183 dump_end (TDI_vcg
, dump_file
);
187 /* Dump a textual representation of the flowgraph. */
189 dump_tree_cfg (dump_file
, dump_flags
);
193 execute_build_cfg (void)
195 build_tree_cfg (&DECL_SAVED_TREE (current_function_decl
));
198 struct tree_opt_pass pass_build_cfg
=
202 execute_build_cfg
, /* execute */
205 0, /* static_pass_number */
206 TV_TREE_CFG
, /* tv_id */
207 PROP_gimple_leh
, /* properties_required */
208 PROP_cfg
, /* properties_provided */
209 0, /* properties_destroyed */
210 0, /* todo_flags_start */
211 TODO_verify_stmts
/* todo_flags_finish */
214 /* Search the CFG for any computed gotos. If found, factor them to a
215 common computed goto site. Also record the location of that site so
216 that we can un-factor the gotos after we have converted back to
220 factor_computed_gotos (void)
223 tree factored_label_decl
= NULL
;
225 tree factored_computed_goto_label
= NULL
;
226 tree factored_computed_goto
= NULL
;
228 /* We know there are one or more computed gotos in this function.
229 Examine the last statement in each basic block to see if the block
230 ends with a computed goto. */
234 block_stmt_iterator bsi
= bsi_last (bb
);
239 last
= bsi_stmt (bsi
);
241 /* Ignore the computed goto we create when we factor the original
243 if (last
== factored_computed_goto
)
246 /* If the last statement is a computed goto, factor it. */
247 if (computed_goto_p (last
))
251 /* The first time we find a computed goto we need to create
252 the factored goto block and the variable each original
253 computed goto will use for their goto destination. */
254 if (! factored_computed_goto
)
256 basic_block new_bb
= create_empty_bb (bb
);
257 block_stmt_iterator new_bsi
= bsi_start (new_bb
);
259 /* Create the destination of the factored goto. Each original
260 computed goto will put its desired destination into this
261 variable and jump to the label we create immediately
263 var
= create_tmp_var (ptr_type_node
, "gotovar");
265 /* Build a label for the new block which will contain the
266 factored computed goto. */
267 factored_label_decl
= create_artificial_label ();
268 factored_computed_goto_label
269 = build1 (LABEL_EXPR
, void_type_node
, factored_label_decl
);
270 bsi_insert_after (&new_bsi
, factored_computed_goto_label
,
273 /* Build our new computed goto. */
274 factored_computed_goto
= build1 (GOTO_EXPR
, void_type_node
, var
);
275 bsi_insert_after (&new_bsi
, factored_computed_goto
,
279 /* Copy the original computed goto's destination into VAR. */
280 assignment
= build (MODIFY_EXPR
, ptr_type_node
,
281 var
, GOTO_DESTINATION (last
));
282 bsi_insert_before (&bsi
, assignment
, BSI_SAME_STMT
);
284 /* And re-vector the computed goto to the new destination. */
285 GOTO_DESTINATION (last
) = factored_label_decl
;
291 /* Create annotations for a single basic block. */
294 create_block_annotation (basic_block bb
)
296 /* Verify that the tree_annotations field is clear. */
297 if (bb
->tree_annotations
)
299 bb
->tree_annotations
= ggc_alloc_cleared (sizeof (struct bb_ann_d
));
303 /* Free the annotations for all the basic blocks. */
305 static void free_blocks_annotations (void)
307 clear_blocks_annotations ();
311 /* Clear the annotations for all the basic blocks. */
314 clear_blocks_annotations (void)
318 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
, NULL
, next_bb
)
319 bb
->tree_annotations
= NULL
;
323 /* Build a flowgraph for the statement_list STMT_LIST. */
326 make_blocks (tree stmt_list
)
328 tree_stmt_iterator i
= tsi_start (stmt_list
);
330 bool start_new_block
= true;
331 bool first_stmt_of_list
= true;
332 basic_block bb
= ENTRY_BLOCK_PTR
;
334 while (!tsi_end_p (i
))
341 /* If the statement starts a new basic block or if we have determined
342 in a previous pass that we need to create a new block for STMT, do
344 if (start_new_block
|| stmt_starts_bb_p (stmt
, prev_stmt
))
346 if (!first_stmt_of_list
)
347 stmt_list
= tsi_split_statement_list_before (&i
);
348 bb
= create_basic_block (stmt_list
, NULL
, bb
);
349 start_new_block
= false;
352 /* Now add STMT to BB and create the subgraphs for special statement
354 set_bb_for_stmt (stmt
, bb
);
356 if (computed_goto_p (stmt
))
357 found_computed_goto
= true;
359 /* If STMT is a basic block terminator, set START_NEW_BLOCK for the
361 if (stmt_ends_bb_p (stmt
))
362 start_new_block
= true;
365 first_stmt_of_list
= false;
370 /* Create and return a new empty basic block after bb AFTER. */
373 create_bb (void *h
, void *e
, basic_block after
)
380 /* Create and initialize a new basic block. */
382 memset (bb
, 0, sizeof (*bb
));
384 bb
->index
= last_basic_block
;
386 bb
->stmt_list
= h
? h
: alloc_stmt_list ();
388 /* Add the new block to the linked list of blocks. */
389 link_block (bb
, after
);
391 /* Grow the basic block array if needed. */
392 if ((size_t) last_basic_block
== VARRAY_SIZE (basic_block_info
))
394 size_t new_size
= last_basic_block
+ (last_basic_block
+ 3) / 4;
395 VARRAY_GROW (basic_block_info
, new_size
);
398 /* Add the newly created block to the array. */
399 BASIC_BLOCK (last_basic_block
) = bb
;
401 create_block_annotation (bb
);
406 initialize_bb_rbi (bb
);
411 /*---------------------------------------------------------------------------
413 ---------------------------------------------------------------------------*/
415 /* Join all the blocks in the flowgraph. */
422 /* Create an edge from entry to the first block with executable
424 make_edge (ENTRY_BLOCK_PTR
, BASIC_BLOCK (0), EDGE_FALLTHRU
);
426 /* Traverse basic block array placing edges. */
429 tree first
= first_stmt (bb
);
430 tree last
= last_stmt (bb
);
434 /* Edges for statements that always alter flow control. */
435 if (is_ctrl_stmt (last
))
436 make_ctrl_stmt_edges (bb
);
438 /* Edges for statements that sometimes alter flow control. */
439 if (is_ctrl_altering_stmt (last
))
440 make_exit_edges (bb
);
443 /* Finally, if no edges were created above, this is a regular
444 basic block that only needs a fallthru edge. */
445 if (bb
->succ
== NULL
)
446 make_edge (bb
, bb
->next_bb
, EDGE_FALLTHRU
);
449 /* We do not care about fake edges, so remove any that the CFG
450 builder inserted for completeness. */
451 remove_fake_edges ();
453 /* Clean up the graph and warn for unreachable code. */
458 /* Create edges for control statement at basic block BB. */
461 make_ctrl_stmt_edges (basic_block bb
)
463 tree last
= last_stmt (bb
);
464 tree first
= first_stmt (bb
);
466 #if defined ENABLE_CHECKING
467 if (last
== NULL_TREE
)
471 if (TREE_CODE (first
) == LABEL_EXPR
472 && DECL_NONLOCAL (LABEL_EXPR_LABEL (first
)))
473 make_edge (ENTRY_BLOCK_PTR
, bb
, EDGE_ABNORMAL
);
475 switch (TREE_CODE (last
))
478 make_goto_expr_edges (bb
);
482 make_edge (bb
, EXIT_BLOCK_PTR
, 0);
486 make_cond_expr_edges (bb
);
490 make_switch_expr_edges (bb
);
494 make_eh_edges (last
);
495 /* Yet another NORETURN hack. */
496 if (bb
->succ
== NULL
)
497 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
506 /* Create exit edges for statements in block BB that alter the flow of
507 control. Statements that alter the control flow are 'goto', 'return'
508 and calls to non-returning functions. */
511 make_exit_edges (basic_block bb
)
513 tree last
= last_stmt (bb
), op
;
515 if (last
== NULL_TREE
)
518 switch (TREE_CODE (last
))
521 /* If this function receives a nonlocal goto, then we need to
522 make edges from this call site to all the nonlocal goto
524 if (TREE_SIDE_EFFECTS (last
)
525 && current_function_has_nonlocal_label
)
526 make_goto_expr_edges (bb
);
528 /* If this statement has reachable exception handlers, then
529 create abnormal edges to them. */
530 make_eh_edges (last
);
532 /* Some calls are known not to return. For such calls we create
535 We really need to revamp how we build edges so that it's not
536 such a bloody pain to avoid creating edges for this case since
537 all we do is remove these edges when we're done building the
539 if (call_expr_flags (last
) & (ECF_NORETURN
| ECF_LONGJMP
))
541 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
545 /* Don't forget the fall-thru edge. */
546 make_edge (bb
, bb
->next_bb
, EDGE_FALLTHRU
);
550 /* A MODIFY_EXPR may have a CALL_EXPR on its RHS and the CALL_EXPR
551 may have an abnormal edge. Search the RHS for this case and
552 create any required edges. */
553 op
= get_call_expr_in (last
);
554 if (op
&& TREE_SIDE_EFFECTS (op
)
555 && current_function_has_nonlocal_label
)
556 make_goto_expr_edges (bb
);
558 make_eh_edges (last
);
559 make_edge (bb
, bb
->next_bb
, EDGE_FALLTHRU
);
568 /* Create the edges for a COND_EXPR starting at block BB.
569 At this point, both clauses must contain only simple gotos. */
572 make_cond_expr_edges (basic_block bb
)
574 tree entry
= last_stmt (bb
);
575 basic_block then_bb
, else_bb
;
576 tree then_label
, else_label
;
578 #if defined ENABLE_CHECKING
579 if (entry
== NULL_TREE
|| TREE_CODE (entry
) != COND_EXPR
)
583 /* Entry basic blocks for each component. */
584 then_label
= GOTO_DESTINATION (COND_EXPR_THEN (entry
));
585 else_label
= GOTO_DESTINATION (COND_EXPR_ELSE (entry
));
586 then_bb
= label_to_block (then_label
);
587 else_bb
= label_to_block (else_label
);
589 make_edge (bb
, then_bb
, EDGE_TRUE_VALUE
);
590 make_edge (bb
, else_bb
, EDGE_FALSE_VALUE
);
594 /* Create the edges for a SWITCH_EXPR starting at block BB.
595 At this point, the switch body has been lowered and the
596 SWITCH_LABELS filled in, so this is in effect a multi-way branch. */
599 make_switch_expr_edges (basic_block bb
)
601 tree entry
= last_stmt (bb
);
605 vec
= SWITCH_LABELS (entry
);
606 n
= TREE_VEC_LENGTH (vec
);
608 for (i
= 0; i
< n
; ++i
)
610 tree lab
= CASE_LABEL (TREE_VEC_ELT (vec
, i
));
611 basic_block label_bb
= label_to_block (lab
);
612 make_edge (bb
, label_bb
, 0);
617 /* Return the basic block holding label DEST. */
620 label_to_block (tree dest
)
622 int uid
= LABEL_DECL_UID (dest
);
624 /* We would die hard when faced by undefined label. Emit label to
625 very first basic block. This will hopefully make even the dataflow
626 and undefined variable warnings quite right. */
627 if ((errorcount
|| sorrycount
) && uid
< 0)
629 block_stmt_iterator bsi
= bsi_start (BASIC_BLOCK (0));
632 stmt
= build1 (LABEL_EXPR
, void_type_node
, dest
);
633 bsi_insert_before (&bsi
, stmt
, BSI_NEW_STMT
);
634 uid
= LABEL_DECL_UID (dest
);
636 return VARRAY_BB (label_to_block_map
, uid
);
640 /* Create edges for a goto statement at block BB. */
643 make_goto_expr_edges (basic_block bb
)
646 basic_block target_bb
;
648 block_stmt_iterator last
= bsi_last (bb
);
650 goto_t
= bsi_stmt (last
);
652 /* If the last statement is not a GOTO (i.e., it is a RETURN_EXPR,
653 CALL_EXPR or MODIFY_EXPR), then the edge is an abnormal edge resulting
654 from a nonlocal goto. */
655 if (TREE_CODE (goto_t
) != GOTO_EXPR
)
657 dest
= error_mark_node
;
662 dest
= GOTO_DESTINATION (goto_t
);
665 /* A GOTO to a local label creates normal edges. */
666 if (simple_goto_p (goto_t
))
668 edge e
= make_edge (bb
, label_to_block (dest
), EDGE_FALLTHRU
);
669 #ifdef USE_MAPPED_LOCATION
670 e
->goto_locus
= EXPR_LOCATION (goto_t
);
672 e
->goto_locus
= EXPR_LOCUS (goto_t
);
678 /* Nothing more to do for nonlocal gotos. */
679 if (TREE_CODE (dest
) == LABEL_DECL
)
682 /* Computed gotos remain. */
685 /* Look for the block starting with the destination label. In the
686 case of a computed goto, make an edge to any label block we find
688 FOR_EACH_BB (target_bb
)
690 block_stmt_iterator bsi
;
692 for (bsi
= bsi_start (target_bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
694 tree target
= bsi_stmt (bsi
);
696 if (TREE_CODE (target
) != LABEL_EXPR
)
700 /* Computed GOTOs. Make an edge to every label block that has
701 been marked as a potential target for a computed goto. */
702 (FORCED_LABEL (LABEL_EXPR_LABEL (target
)) && for_call
== 0)
703 /* Nonlocal GOTO target. Make an edge to every label block
704 that has been marked as a potential target for a nonlocal
706 || (DECL_NONLOCAL (LABEL_EXPR_LABEL (target
)) && for_call
== 1))
708 make_edge (bb
, target_bb
, EDGE_ABNORMAL
);
714 /* Degenerate case of computed goto with no labels. */
715 if (!for_call
&& !bb
->succ
)
716 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
720 /*---------------------------------------------------------------------------
722 ---------------------------------------------------------------------------*/
724 /* Remove unreachable blocks and other miscellaneous clean up work. */
727 cleanup_tree_cfg (void)
729 bool something_changed
= true;
731 timevar_push (TV_TREE_CLEANUP_CFG
);
733 /* These three transformations can cascade, so we iterate on them until
735 while (something_changed
)
737 something_changed
= cleanup_control_flow ();
738 something_changed
|= thread_jumps ();
739 something_changed
|= delete_unreachable_blocks ();
742 /* Merging the blocks creates no new opportunities for the other
743 optimizations, so do it here. */
748 #ifdef ENABLE_CHECKING
751 timevar_pop (TV_TREE_CLEANUP_CFG
);
755 /* Cleanup useless labels in basic blocks. This is something we wish
756 to do early because it allows us to group case labels before creating
757 the edges for the CFG, and it speeds up block statement iterators in
759 We only run this pass once, running it more than once is probably not
762 /* A map from basic block index to the leading label of that block. */
763 static tree
*label_for_bb
;
765 /* Callback for for_each_eh_region. Helper for cleanup_dead_labels. */
767 update_eh_label (struct eh_region
*region
)
769 tree old_label
= get_eh_region_tree_label (region
);
772 tree new_label
= label_for_bb
[label_to_block (old_label
)->index
];
773 set_eh_region_tree_label (region
, new_label
);
777 /* Given LABEL return the first label in the same basic block. */
779 main_block_label (tree label
)
781 basic_block bb
= label_to_block (label
);
783 /* label_to_block possibly inserted undefined label into the chain. */
784 if (!label_for_bb
[bb
->index
])
785 label_for_bb
[bb
->index
] = label
;
786 return label_for_bb
[bb
->index
];
789 /* Cleanup redundant labels. This is a three-steo process:
790 1) Find the leading label for each block.
791 2) Redirect all references to labels to the leading labels.
792 3) Cleanup all useless labels. */
795 cleanup_dead_labels (void)
798 label_for_bb
= xcalloc (last_basic_block
, sizeof (tree
));
800 /* Find a suitable label for each block. We use the first user-defined
801 label is there is one, or otherwise just the first label we see. */
804 block_stmt_iterator i
;
806 for (i
= bsi_start (bb
); !bsi_end_p (i
); bsi_next (&i
))
808 tree label
, stmt
= bsi_stmt (i
);
810 if (TREE_CODE (stmt
) != LABEL_EXPR
)
813 label
= LABEL_EXPR_LABEL (stmt
);
815 /* If we have not yet seen a label for the current block,
816 remember this one and see if there are more labels. */
817 if (! label_for_bb
[bb
->index
])
819 label_for_bb
[bb
->index
] = label
;
823 /* If we did see a label for the current block already, but it
824 is an artificially created label, replace it if the current
825 label is a user defined label. */
826 if (! DECL_ARTIFICIAL (label
)
827 && DECL_ARTIFICIAL (label_for_bb
[bb
->index
]))
829 label_for_bb
[bb
->index
] = label
;
835 /* Now redirect all jumps/branches to the selected label.
836 First do so for each block ending in a control statement. */
839 tree stmt
= last_stmt (bb
);
843 switch (TREE_CODE (stmt
))
847 tree true_branch
, false_branch
;
849 true_branch
= COND_EXPR_THEN (stmt
);
850 false_branch
= COND_EXPR_ELSE (stmt
);
852 GOTO_DESTINATION (true_branch
)
853 = main_block_label (GOTO_DESTINATION (true_branch
));
854 GOTO_DESTINATION (false_branch
)
855 = main_block_label (GOTO_DESTINATION (false_branch
));
863 tree vec
= SWITCH_LABELS (stmt
);
864 size_t n
= TREE_VEC_LENGTH (vec
);
866 /* Replace all destination labels. */
867 for (i
= 0; i
< n
; ++i
)
868 CASE_LABEL (TREE_VEC_ELT (vec
, i
))
869 = main_block_label (CASE_LABEL (TREE_VEC_ELT (vec
, i
)));
874 /* We have to handle GOTO_EXPRs until they're removed, and we don't
875 remove them until after we've created the CFG edges. */
877 if (! computed_goto_p (stmt
))
879 GOTO_DESTINATION (stmt
)
880 = main_block_label (GOTO_DESTINATION (stmt
));
889 for_each_eh_region (update_eh_label
);
891 /* Finally, purge dead labels. All user-defined labels and labels that
892 can be the target of non-local gotos are preserved. */
895 block_stmt_iterator i
;
896 tree label_for_this_bb
= label_for_bb
[bb
->index
];
898 if (! label_for_this_bb
)
901 for (i
= bsi_start (bb
); !bsi_end_p (i
); )
903 tree label
, stmt
= bsi_stmt (i
);
905 if (TREE_CODE (stmt
) != LABEL_EXPR
)
908 label
= LABEL_EXPR_LABEL (stmt
);
910 if (label
== label_for_this_bb
911 || ! DECL_ARTIFICIAL (label
)
912 || DECL_NONLOCAL (label
))
922 /* Look for blocks ending in a multiway branch (a SWITCH_EXPR in GIMPLE),
923 and scan the sorted vector of cases. Combine the ones jumping to the
925 Eg. three separate entries 1: 2: 3: become one entry 1..3: */
928 group_case_labels (void)
934 tree stmt
= last_stmt (bb
);
935 if (stmt
&& TREE_CODE (stmt
) == SWITCH_EXPR
)
937 tree labels
= SWITCH_LABELS (stmt
);
938 int old_size
= TREE_VEC_LENGTH (labels
);
939 int i
, j
, new_size
= old_size
;
940 tree default_label
= TREE_VEC_ELT (labels
, old_size
- 1);
942 /* Look for possible opportunities to merge cases.
943 Ignore the last element of the label vector because it
944 must be the default case. */
946 while (i
< old_size
- 2)
948 tree base_case
, base_label
, base_high
, type
;
949 base_case
= TREE_VEC_ELT (labels
, i
);
954 base_label
= CASE_LABEL (base_case
);
956 /* Discard cases that have the same destination as the
958 if (base_label
== default_label
)
960 TREE_VEC_ELT (labels
, i
) = NULL_TREE
;
965 type
= TREE_TYPE (CASE_LOW (base_case
));
966 base_high
= CASE_HIGH (base_case
) ?
967 CASE_HIGH (base_case
) : CASE_LOW (base_case
);
969 /* Try to merge case labels. Break out when we reach the end
970 of the label vector or when we cannot merge the next case
971 label with the current one. */
972 while (i
< old_size
- 2)
974 tree merge_case
= TREE_VEC_ELT (labels
, ++i
);
975 tree merge_label
= CASE_LABEL (merge_case
);
976 tree t
= int_const_binop (PLUS_EXPR
, base_high
,
977 integer_one_node
, 1);
979 /* Merge the cases if they jump to the same place,
980 and their ranges are consecutive. */
981 if (merge_label
== base_label
982 && tree_int_cst_equal (CASE_LOW (merge_case
), t
))
984 base_high
= CASE_HIGH (merge_case
) ?
985 CASE_HIGH (merge_case
) : CASE_LOW (merge_case
);
986 CASE_HIGH (base_case
) = base_high
;
987 TREE_VEC_ELT (labels
, i
) = NULL_TREE
;
995 /* Compress the case labels in the label vector, and adjust the
996 length of the vector. */
997 for (i
= 0, j
= 0; i
< new_size
; i
++)
999 while (! TREE_VEC_ELT (labels
, j
))
1001 TREE_VEC_ELT (labels
, i
) = TREE_VEC_ELT (labels
, j
++);
1003 TREE_VEC_LENGTH (labels
) = new_size
;
1008 /* Checks whether we can merge block B into block A. */
1011 tree_can_merge_blocks_p (basic_block a
, basic_block b
)
1014 block_stmt_iterator bsi
;
1017 || a
->succ
->succ_next
)
1020 if (a
->succ
->flags
& EDGE_ABNORMAL
)
1023 if (a
->succ
->dest
!= b
)
1026 if (b
== EXIT_BLOCK_PTR
)
1029 if (b
->pred
->pred_next
)
1032 /* If A ends by a statement causing exceptions or something similar, we
1033 cannot merge the blocks. */
1034 stmt
= last_stmt (a
);
1035 if (stmt
&& stmt_ends_bb_p (stmt
))
1038 /* Do not allow a block with only a non-local label to be merged. */
1039 if (stmt
&& TREE_CODE (stmt
) == LABEL_EXPR
1040 && DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt
)))
1043 /* There may be no phi nodes at the start of b. Most of these degenerate
1044 phi nodes should be cleaned up by kill_redundant_phi_nodes. */
1048 /* Do not remove user labels. */
1049 for (bsi
= bsi_start (b
); !bsi_end_p (bsi
); bsi_next (&bsi
))
1051 stmt
= bsi_stmt (bsi
);
1052 if (TREE_CODE (stmt
) != LABEL_EXPR
)
1054 if (!DECL_ARTIFICIAL (LABEL_EXPR_LABEL (stmt
)))
1062 /* Merge block B into block A. */
1065 tree_merge_blocks (basic_block a
, basic_block b
)
1067 block_stmt_iterator bsi
;
1068 tree_stmt_iterator last
;
1071 fprintf (dump_file
, "Merging blocks %d and %d\n", a
->index
, b
->index
);
1073 /* Ensure that B follows A. */
1074 move_block_after (b
, a
);
1076 if (!(a
->succ
->flags
& EDGE_FALLTHRU
))
1080 && stmt_ends_bb_p (last_stmt (a
)))
1083 /* Remove labels from B and set bb_for_stmt to A for other statements. */
1084 for (bsi
= bsi_start (b
); !bsi_end_p (bsi
);)
1086 if (TREE_CODE (bsi_stmt (bsi
)) == LABEL_EXPR
)
1090 set_bb_for_stmt (bsi_stmt (bsi
), a
);
1095 /* Merge the chains. */
1096 last
= tsi_last (a
->stmt_list
);
1097 tsi_link_after (&last
, b
->stmt_list
, TSI_NEW_STMT
);
1098 b
->stmt_list
= NULL
;
1102 /* Walk the function tree removing unnecessary statements.
1104 * Empty statement nodes are removed
1106 * Unnecessary TRY_FINALLY and TRY_CATCH blocks are removed
1108 * Unnecessary COND_EXPRs are removed
1110 * Some unnecessary BIND_EXPRs are removed
1112 Clearly more work could be done. The trick is doing the analysis
1113 and removal fast enough to be a net improvement in compile times.
1115 Note that when we remove a control structure such as a COND_EXPR
1116 BIND_EXPR, or TRY block, we will need to repeat this optimization pass
1117 to ensure we eliminate all the useless code. */
1128 static void remove_useless_stmts_1 (tree
*, struct rus_data
*);
1131 remove_useless_stmts_warn_notreached (tree stmt
)
1133 if (EXPR_HAS_LOCATION (stmt
))
1135 location_t loc
= EXPR_LOCATION (stmt
);
1136 warning ("%Hwill never be executed", &loc
);
1140 switch (TREE_CODE (stmt
))
1142 case STATEMENT_LIST
:
1144 tree_stmt_iterator i
;
1145 for (i
= tsi_start (stmt
); !tsi_end_p (i
); tsi_next (&i
))
1146 if (remove_useless_stmts_warn_notreached (tsi_stmt (i
)))
1152 if (remove_useless_stmts_warn_notreached (COND_EXPR_COND (stmt
)))
1154 if (remove_useless_stmts_warn_notreached (COND_EXPR_THEN (stmt
)))
1156 if (remove_useless_stmts_warn_notreached (COND_EXPR_ELSE (stmt
)))
1160 case TRY_FINALLY_EXPR
:
1161 case TRY_CATCH_EXPR
:
1162 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt
, 0)))
1164 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt
, 1)))
1169 return remove_useless_stmts_warn_notreached (CATCH_BODY (stmt
));
1170 case EH_FILTER_EXPR
:
1171 return remove_useless_stmts_warn_notreached (EH_FILTER_FAILURE (stmt
));
1173 return remove_useless_stmts_warn_notreached (BIND_EXPR_BLOCK (stmt
));
1176 /* Not a live container. */
1184 remove_useless_stmts_cond (tree
*stmt_p
, struct rus_data
*data
)
1186 tree then_clause
, else_clause
, cond
;
1187 bool save_has_label
, then_has_label
, else_has_label
;
1189 save_has_label
= data
->has_label
;
1190 data
->has_label
= false;
1191 data
->last_goto
= NULL
;
1193 remove_useless_stmts_1 (&COND_EXPR_THEN (*stmt_p
), data
);
1195 then_has_label
= data
->has_label
;
1196 data
->has_label
= false;
1197 data
->last_goto
= NULL
;
1199 remove_useless_stmts_1 (&COND_EXPR_ELSE (*stmt_p
), data
);
1201 else_has_label
= data
->has_label
;
1202 data
->has_label
= save_has_label
| then_has_label
| else_has_label
;
1205 then_clause
= COND_EXPR_THEN (*stmt_p
);
1206 else_clause
= COND_EXPR_ELSE (*stmt_p
);
1207 cond
= COND_EXPR_COND (*stmt_p
);
1209 /* If neither arm does anything at all, we can remove the whole IF. */
1210 if (!TREE_SIDE_EFFECTS (then_clause
) && !TREE_SIDE_EFFECTS (else_clause
))
1212 *stmt_p
= build_empty_stmt ();
1213 data
->repeat
= true;
1216 /* If there are no reachable statements in an arm, then we can
1217 zap the entire conditional. */
1218 else if (integer_nonzerop (cond
) && !else_has_label
)
1220 if (warn_notreached
)
1221 remove_useless_stmts_warn_notreached (else_clause
);
1222 *stmt_p
= then_clause
;
1223 data
->repeat
= true;
1225 else if (integer_zerop (cond
) && !then_has_label
)
1227 if (warn_notreached
)
1228 remove_useless_stmts_warn_notreached (then_clause
);
1229 *stmt_p
= else_clause
;
1230 data
->repeat
= true;
1233 /* Check a couple of simple things on then/else with single stmts. */
1236 tree then_stmt
= expr_only (then_clause
);
1237 tree else_stmt
= expr_only (else_clause
);
1239 /* Notice branches to a common destination. */
1240 if (then_stmt
&& else_stmt
1241 && TREE_CODE (then_stmt
) == GOTO_EXPR
1242 && TREE_CODE (else_stmt
) == GOTO_EXPR
1243 && (GOTO_DESTINATION (then_stmt
) == GOTO_DESTINATION (else_stmt
)))
1245 *stmt_p
= then_stmt
;
1246 data
->repeat
= true;
1249 /* If the THEN/ELSE clause merely assigns a value to a variable or
1250 parameter which is already known to contain that value, then
1251 remove the useless THEN/ELSE clause. */
1252 else if (TREE_CODE (cond
) == VAR_DECL
|| TREE_CODE (cond
) == PARM_DECL
)
1255 && TREE_CODE (else_stmt
) == MODIFY_EXPR
1256 && TREE_OPERAND (else_stmt
, 0) == cond
1257 && integer_zerop (TREE_OPERAND (else_stmt
, 1)))
1258 COND_EXPR_ELSE (*stmt_p
) = alloc_stmt_list ();
1260 else if ((TREE_CODE (cond
) == EQ_EXPR
|| TREE_CODE (cond
) == NE_EXPR
)
1261 && (TREE_CODE (TREE_OPERAND (cond
, 0)) == VAR_DECL
1262 || TREE_CODE (TREE_OPERAND (cond
, 0)) == PARM_DECL
)
1263 && TREE_CONSTANT (TREE_OPERAND (cond
, 1)))
1265 tree stmt
= (TREE_CODE (cond
) == EQ_EXPR
1266 ? then_stmt
: else_stmt
);
1267 tree
*location
= (TREE_CODE (cond
) == EQ_EXPR
1268 ? &COND_EXPR_THEN (*stmt_p
)
1269 : &COND_EXPR_ELSE (*stmt_p
));
1272 && TREE_CODE (stmt
) == MODIFY_EXPR
1273 && TREE_OPERAND (stmt
, 0) == TREE_OPERAND (cond
, 0)
1274 && TREE_OPERAND (stmt
, 1) == TREE_OPERAND (cond
, 1))
1275 *location
= alloc_stmt_list ();
1279 /* Protect GOTOs in the arm of COND_EXPRs from being removed. They
1280 would be re-introduced during lowering. */
1281 data
->last_goto
= NULL
;
1286 remove_useless_stmts_tf (tree
*stmt_p
, struct rus_data
*data
)
1288 bool save_may_branch
, save_may_throw
;
1289 bool this_may_branch
, this_may_throw
;
1291 /* Collect may_branch and may_throw information for the body only. */
1292 save_may_branch
= data
->may_branch
;
1293 save_may_throw
= data
->may_throw
;
1294 data
->may_branch
= false;
1295 data
->may_throw
= false;
1296 data
->last_goto
= NULL
;
1298 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p
, 0), data
);
1300 this_may_branch
= data
->may_branch
;
1301 this_may_throw
= data
->may_throw
;
1302 data
->may_branch
|= save_may_branch
;
1303 data
->may_throw
|= save_may_throw
;
1304 data
->last_goto
= NULL
;
1306 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p
, 1), data
);
1308 /* If the body is empty, then we can emit the FINALLY block without
1309 the enclosing TRY_FINALLY_EXPR. */
1310 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p
, 0)))
1312 *stmt_p
= TREE_OPERAND (*stmt_p
, 1);
1313 data
->repeat
= true;
1316 /* If the handler is empty, then we can emit the TRY block without
1317 the enclosing TRY_FINALLY_EXPR. */
1318 else if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p
, 1)))
1320 *stmt_p
= TREE_OPERAND (*stmt_p
, 0);
1321 data
->repeat
= true;
1324 /* If the body neither throws, nor branches, then we can safely
1325 string the TRY and FINALLY blocks together. */
1326 else if (!this_may_branch
&& !this_may_throw
)
1328 tree stmt
= *stmt_p
;
1329 *stmt_p
= TREE_OPERAND (stmt
, 0);
1330 append_to_statement_list (TREE_OPERAND (stmt
, 1), stmt_p
);
1331 data
->repeat
= true;
1337 remove_useless_stmts_tc (tree
*stmt_p
, struct rus_data
*data
)
1339 bool save_may_throw
, this_may_throw
;
1340 tree_stmt_iterator i
;
1343 /* Collect may_throw information for the body only. */
1344 save_may_throw
= data
->may_throw
;
1345 data
->may_throw
= false;
1346 data
->last_goto
= NULL
;
1348 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p
, 0), data
);
1350 this_may_throw
= data
->may_throw
;
1351 data
->may_throw
= save_may_throw
;
1353 /* If the body cannot throw, then we can drop the entire TRY_CATCH_EXPR. */
1354 if (!this_may_throw
)
1356 if (warn_notreached
)
1357 remove_useless_stmts_warn_notreached (TREE_OPERAND (*stmt_p
, 1));
1358 *stmt_p
= TREE_OPERAND (*stmt_p
, 0);
1359 data
->repeat
= true;
1363 /* Process the catch clause specially. We may be able to tell that
1364 no exceptions propagate past this point. */
1366 this_may_throw
= true;
1367 i
= tsi_start (TREE_OPERAND (*stmt_p
, 1));
1368 stmt
= tsi_stmt (i
);
1369 data
->last_goto
= NULL
;
1371 switch (TREE_CODE (stmt
))
1374 for (; !tsi_end_p (i
); tsi_next (&i
))
1376 stmt
= tsi_stmt (i
);
1377 /* If we catch all exceptions, then the body does not
1378 propagate exceptions past this point. */
1379 if (CATCH_TYPES (stmt
) == NULL
)
1380 this_may_throw
= false;
1381 data
->last_goto
= NULL
;
1382 remove_useless_stmts_1 (&CATCH_BODY (stmt
), data
);
1386 case EH_FILTER_EXPR
:
1387 if (EH_FILTER_MUST_NOT_THROW (stmt
))
1388 this_may_throw
= false;
1389 else if (EH_FILTER_TYPES (stmt
) == NULL
)
1390 this_may_throw
= false;
1391 remove_useless_stmts_1 (&EH_FILTER_FAILURE (stmt
), data
);
1395 /* Otherwise this is a cleanup. */
1396 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p
, 1), data
);
1398 /* If the cleanup is empty, then we can emit the TRY block without
1399 the enclosing TRY_CATCH_EXPR. */
1400 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p
, 1)))
1402 *stmt_p
= TREE_OPERAND (*stmt_p
, 0);
1403 data
->repeat
= true;
1407 data
->may_throw
|= this_may_throw
;
1412 remove_useless_stmts_bind (tree
*stmt_p
, struct rus_data
*data
)
1416 /* First remove anything underneath the BIND_EXPR. */
1417 remove_useless_stmts_1 (&BIND_EXPR_BODY (*stmt_p
), data
);
1419 /* If the BIND_EXPR has no variables, then we can pull everything
1420 up one level and remove the BIND_EXPR, unless this is the toplevel
1421 BIND_EXPR for the current function or an inlined function.
1423 When this situation occurs we will want to apply this
1424 optimization again. */
1425 block
= BIND_EXPR_BLOCK (*stmt_p
);
1426 if (BIND_EXPR_VARS (*stmt_p
) == NULL_TREE
1427 && *stmt_p
!= DECL_SAVED_TREE (current_function_decl
)
1429 || ! BLOCK_ABSTRACT_ORIGIN (block
)
1430 || (TREE_CODE (BLOCK_ABSTRACT_ORIGIN (block
))
1433 *stmt_p
= BIND_EXPR_BODY (*stmt_p
);
1434 data
->repeat
= true;
1440 remove_useless_stmts_goto (tree
*stmt_p
, struct rus_data
*data
)
1442 tree dest
= GOTO_DESTINATION (*stmt_p
);
1444 data
->may_branch
= true;
1445 data
->last_goto
= NULL
;
1447 /* Record the last goto expr, so that we can delete it if unnecessary. */
1448 if (TREE_CODE (dest
) == LABEL_DECL
)
1449 data
->last_goto
= stmt_p
;
1454 remove_useless_stmts_label (tree
*stmt_p
, struct rus_data
*data
)
1456 tree label
= LABEL_EXPR_LABEL (*stmt_p
);
1458 data
->has_label
= true;
1460 /* We do want to jump across non-local label receiver code. */
1461 if (DECL_NONLOCAL (label
))
1462 data
->last_goto
= NULL
;
1464 else if (data
->last_goto
&& GOTO_DESTINATION (*data
->last_goto
) == label
)
1466 *data
->last_goto
= build_empty_stmt ();
1467 data
->repeat
= true;
1470 /* ??? Add something here to delete unused labels. */
1474 /* If the function is "const" or "pure", then clear TREE_SIDE_EFFECTS on its
1475 decl. This allows us to eliminate redundant or useless
1476 calls to "const" functions.
1478 Gimplifier already does the same operation, but we may notice functions
1479 being const and pure once their calls has been gimplified, so we need
1480 to update the flag. */
1483 update_call_expr_flags (tree call
)
1485 tree decl
= get_callee_fndecl (call
);
1488 if (call_expr_flags (call
) & (ECF_CONST
| ECF_PURE
))
1489 TREE_SIDE_EFFECTS (call
) = 0;
1490 if (TREE_NOTHROW (decl
))
1491 TREE_NOTHROW (call
) = 1;
1495 /* T is CALL_EXPR. Set current_function_calls_* flags. */
1498 notice_special_calls (tree t
)
1500 int flags
= call_expr_flags (t
);
1502 if (flags
& ECF_MAY_BE_ALLOCA
)
1503 current_function_calls_alloca
= true;
1504 if (flags
& ECF_RETURNS_TWICE
)
1505 current_function_calls_setjmp
= true;
1509 /* Clear flags set by notice_special_calls. Used by dead code removal
1510 to update the flags. */
1513 clear_special_calls (void)
1515 current_function_calls_alloca
= false;
1516 current_function_calls_setjmp
= false;
1521 remove_useless_stmts_1 (tree
*tp
, struct rus_data
*data
)
1525 switch (TREE_CODE (t
))
1528 remove_useless_stmts_cond (tp
, data
);
1531 case TRY_FINALLY_EXPR
:
1532 remove_useless_stmts_tf (tp
, data
);
1535 case TRY_CATCH_EXPR
:
1536 remove_useless_stmts_tc (tp
, data
);
1540 remove_useless_stmts_bind (tp
, data
);
1544 remove_useless_stmts_goto (tp
, data
);
1548 remove_useless_stmts_label (tp
, data
);
1553 data
->last_goto
= NULL
;
1554 data
->may_branch
= true;
1559 data
->last_goto
= NULL
;
1560 notice_special_calls (t
);
1561 update_call_expr_flags (t
);
1562 if (tree_could_throw_p (t
))
1563 data
->may_throw
= true;
1567 data
->last_goto
= NULL
;
1569 op
= get_call_expr_in (t
);
1572 update_call_expr_flags (op
);
1573 notice_special_calls (op
);
1575 if (tree_could_throw_p (t
))
1576 data
->may_throw
= true;
1579 case STATEMENT_LIST
:
1581 tree_stmt_iterator i
= tsi_start (t
);
1582 while (!tsi_end_p (i
))
1585 if (IS_EMPTY_STMT (t
))
1591 remove_useless_stmts_1 (tsi_stmt_ptr (i
), data
);
1594 if (TREE_CODE (t
) == STATEMENT_LIST
)
1596 tsi_link_before (&i
, t
, TSI_SAME_STMT
);
1606 data
->last_goto
= NULL
;
1610 data
->last_goto
= NULL
;
1616 remove_useless_stmts (void)
1618 struct rus_data data
;
1620 clear_special_calls ();
1624 memset (&data
, 0, sizeof (data
));
1625 remove_useless_stmts_1 (&DECL_SAVED_TREE (current_function_decl
), &data
);
1627 while (data
.repeat
);
1631 struct tree_opt_pass pass_remove_useless_stmts
=
1633 "useless", /* name */
1635 remove_useless_stmts
, /* execute */
1638 0, /* static_pass_number */
1640 PROP_gimple_any
, /* properties_required */
1641 0, /* properties_provided */
1642 0, /* properties_destroyed */
1643 0, /* todo_flags_start */
1644 TODO_dump_func
/* todo_flags_finish */
1648 /* Remove obviously useless statements in basic block BB. */
1651 cfg_remove_useless_stmts_bb (basic_block bb
)
1653 block_stmt_iterator bsi
;
1654 tree stmt
= NULL_TREE
;
1655 tree cond
, var
= NULL_TREE
, val
= NULL_TREE
;
1656 struct var_ann_d
*ann
;
1658 /* Check whether we come here from a condition, and if so, get the
1661 || bb
->pred
->pred_next
1662 || !(bb
->pred
->flags
& (EDGE_TRUE_VALUE
| EDGE_FALSE_VALUE
)))
1665 cond
= COND_EXPR_COND (last_stmt (bb
->pred
->src
));
1667 if (TREE_CODE (cond
) == VAR_DECL
|| TREE_CODE (cond
) == PARM_DECL
)
1670 val
= (bb
->pred
->flags
& EDGE_FALSE_VALUE
1671 ? boolean_false_node
: boolean_true_node
);
1673 else if (TREE_CODE (cond
) == TRUTH_NOT_EXPR
1674 && (TREE_CODE (TREE_OPERAND (cond
, 0)) == VAR_DECL
1675 || TREE_CODE (TREE_OPERAND (cond
, 0)) == PARM_DECL
))
1677 var
= TREE_OPERAND (cond
, 0);
1678 val
= (bb
->pred
->flags
& EDGE_FALSE_VALUE
1679 ? boolean_true_node
: boolean_false_node
);
1683 if (bb
->pred
->flags
& EDGE_FALSE_VALUE
)
1684 cond
= invert_truthvalue (cond
);
1685 if (TREE_CODE (cond
) == EQ_EXPR
1686 && (TREE_CODE (TREE_OPERAND (cond
, 0)) == VAR_DECL
1687 || TREE_CODE (TREE_OPERAND (cond
, 0)) == PARM_DECL
)
1688 && (TREE_CODE (TREE_OPERAND (cond
, 1)) == VAR_DECL
1689 || TREE_CODE (TREE_OPERAND (cond
, 1)) == PARM_DECL
1690 || TREE_CONSTANT (TREE_OPERAND (cond
, 1))))
1692 var
= TREE_OPERAND (cond
, 0);
1693 val
= TREE_OPERAND (cond
, 1);
1699 /* Only work for normal local variables. */
1700 ann
= var_ann (var
);
1703 || TREE_ADDRESSABLE (var
))
1706 if (! TREE_CONSTANT (val
))
1708 ann
= var_ann (val
);
1711 || TREE_ADDRESSABLE (val
))
1715 /* Ignore floating point variables, since comparison behaves weird for
1717 if (FLOAT_TYPE_P (TREE_TYPE (var
)))
1720 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
);)
1722 stmt
= bsi_stmt (bsi
);
1724 /* If the THEN/ELSE clause merely assigns a value to a variable/parameter
1725 which is already known to contain that value, then remove the useless
1726 THEN/ELSE clause. */
1727 if (TREE_CODE (stmt
) == MODIFY_EXPR
1728 && TREE_OPERAND (stmt
, 0) == var
1729 && operand_equal_p (val
, TREE_OPERAND (stmt
, 1), 0))
1735 /* Invalidate the var if we encounter something that could modify it. */
1736 if (TREE_CODE (stmt
) == ASM_EXPR
1737 || TREE_CODE (stmt
) == VA_ARG_EXPR
1738 || (TREE_CODE (stmt
) == MODIFY_EXPR
1739 && (TREE_OPERAND (stmt
, 0) == var
1740 || TREE_OPERAND (stmt
, 0) == val
1741 || TREE_CODE (TREE_OPERAND (stmt
, 1)) == VA_ARG_EXPR
)))
1749 /* A CFG-aware version of remove_useless_stmts. */
1752 cfg_remove_useless_stmts (void)
1756 #ifdef ENABLE_CHECKING
1757 verify_flow_info ();
1762 cfg_remove_useless_stmts_bb (bb
);
1767 /* Remove PHI nodes associated with basic block BB and all edges out of BB. */
1770 remove_phi_nodes_and_edges_for_unreachable_block (basic_block bb
)
1774 /* Since this block is no longer reachable, we can just delete all
1775 of its PHI nodes. */
1776 phi
= phi_nodes (bb
);
1779 tree next
= PHI_CHAIN (phi
);
1780 remove_phi_node (phi
, NULL_TREE
, bb
);
1784 /* Remove edges to BB's successors. */
1785 while (bb
->succ
!= NULL
)
1786 ssa_remove_edge (bb
->succ
);
1790 /* Remove statements of basic block BB. */
1793 remove_bb (basic_block bb
)
1795 block_stmt_iterator i
;
1796 source_locus loc
= 0;
1800 fprintf (dump_file
, "Removing basic block %d\n", bb
->index
);
1801 if (dump_flags
& TDF_DETAILS
)
1803 dump_bb (bb
, dump_file
, 0);
1804 fprintf (dump_file
, "\n");
1808 /* Remove all the instructions in the block. */
1809 for (i
= bsi_start (bb
); !bsi_end_p (i
); bsi_remove (&i
))
1811 tree stmt
= bsi_stmt (i
);
1813 set_bb_for_stmt (stmt
, NULL
);
1815 /* Don't warn for removed gotos. Gotos are often removed due to
1816 jump threading, thus resulting in bogus warnings. Not great,
1817 since this way we lose warnings for gotos in the original
1818 program that are indeed unreachable. */
1819 if (TREE_CODE (stmt
) != GOTO_EXPR
&& EXPR_HAS_LOCATION (stmt
) && !loc
)
1820 #ifdef USE_MAPPED_LOCATION
1821 loc
= EXPR_LOCATION (stmt
);
1823 loc
= EXPR_LOCUS (stmt
);
1827 /* If requested, give a warning that the first statement in the
1828 block is unreachable. We walk statements backwards in the
1829 loop above, so the last statement we process is the first statement
1831 if (warn_notreached
&& loc
)
1832 #ifdef USE_MAPPED_LOCATION
1833 warning ("%Hwill never be executed", &loc
);
1835 warning ("%Hwill never be executed", loc
);
1838 remove_phi_nodes_and_edges_for_unreachable_block (bb
);
1842 /* Examine BB to determine if it is a forwarding block (a block which only
1843 transfers control to a new destination). If BB is a forwarding block,
1844 then return the edge leading to the ultimate destination. */
1847 tree_block_forwards_to (basic_block bb
)
1849 block_stmt_iterator bsi
;
1850 bb_ann_t ann
= bb_ann (bb
);
1853 /* If this block is not forwardable, then avoid useless work. */
1854 if (! ann
->forwardable
)
1857 /* Set this block to not be forwardable. This prevents infinite loops since
1858 any block currently under examination is considered non-forwardable. */
1859 ann
->forwardable
= 0;
1861 /* No forwarding is possible if this block is a special block (ENTRY/EXIT),
1862 this block has more than one successor, this block's single successor is
1863 reached via an abnormal edge, this block has phi nodes, or this block's
1864 single successor has phi nodes. */
1865 if (bb
== EXIT_BLOCK_PTR
1866 || bb
== ENTRY_BLOCK_PTR
1868 || bb
->succ
->succ_next
1869 || bb
->succ
->dest
== EXIT_BLOCK_PTR
1870 || (bb
->succ
->flags
& EDGE_ABNORMAL
) != 0
1872 || phi_nodes (bb
->succ
->dest
))
1875 /* Walk past any labels at the start of this block. */
1876 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
1878 stmt
= bsi_stmt (bsi
);
1879 if (TREE_CODE (stmt
) != LABEL_EXPR
)
1883 /* If we reached the end of this block we may be able to optimize this
1885 if (bsi_end_p (bsi
))
1889 /* Recursive call to pick up chains of forwarding blocks. */
1890 dest
= tree_block_forwards_to (bb
->succ
->dest
);
1892 /* If none found, we forward to bb->succ at minimum. */
1896 ann
->forwardable
= 1;
1900 /* No forwarding possible. */
1905 /* Try to remove superfluous control structures. */
1908 cleanup_control_flow (void)
1911 block_stmt_iterator bsi
;
1912 bool retval
= false;
1917 bsi
= bsi_last (bb
);
1919 if (bsi_end_p (bsi
))
1922 stmt
= bsi_stmt (bsi
);
1923 if (TREE_CODE (stmt
) == COND_EXPR
1924 || TREE_CODE (stmt
) == SWITCH_EXPR
)
1925 retval
|= cleanup_control_expr_graph (bb
, bsi
);
1931 /* Disconnect an unreachable block in the control expression starting
1935 cleanup_control_expr_graph (basic_block bb
, block_stmt_iterator bsi
)
1938 bool retval
= false;
1939 tree expr
= bsi_stmt (bsi
), val
;
1941 if (bb
->succ
->succ_next
)
1945 switch (TREE_CODE (expr
))
1948 val
= COND_EXPR_COND (expr
);
1952 val
= SWITCH_COND (expr
);
1953 if (TREE_CODE (val
) != INTEGER_CST
)
1961 taken_edge
= find_taken_edge (bb
, val
);
1965 /* Remove all the edges except the one that is always executed. */
1966 for (e
= bb
->succ
; e
; e
= next
)
1968 next
= e
->succ_next
;
1969 if (e
!= taken_edge
)
1971 taken_edge
->probability
+= e
->probability
;
1972 taken_edge
->count
+= e
->count
;
1973 ssa_remove_edge (e
);
1977 if (taken_edge
->probability
> REG_BR_PROB_BASE
)
1978 taken_edge
->probability
= REG_BR_PROB_BASE
;
1981 taken_edge
= bb
->succ
;
1984 taken_edge
->flags
= EDGE_FALLTHRU
;
1986 /* We removed some paths from the cfg. */
1987 if (dom_computed
[CDI_DOMINATORS
] >= DOM_CONS_OK
)
1988 dom_computed
[CDI_DOMINATORS
] = DOM_CONS_OK
;
1994 /* Given a control block BB and a constant value VAL, return the edge that
1995 will be taken out of the block. If VAL does not match a unique edge,
1996 NULL is returned. */
1999 find_taken_edge (basic_block bb
, tree val
)
2003 stmt
= last_stmt (bb
);
2005 #if defined ENABLE_CHECKING
2006 if (stmt
== NULL_TREE
|| !is_ctrl_stmt (stmt
))
2010 /* If VAL is not a constant, we can't determine which edge might
2012 if (val
== NULL
|| !really_constant_p (val
))
2015 if (TREE_CODE (stmt
) == COND_EXPR
)
2016 return find_taken_edge_cond_expr (bb
, val
);
2018 if (TREE_CODE (stmt
) == SWITCH_EXPR
)
2019 return find_taken_edge_switch_expr (bb
, val
);
2025 /* Given a constant value VAL and the entry block BB to a COND_EXPR
2026 statement, determine which of the two edges will be taken out of the
2027 block. Return NULL if either edge may be taken. */
2030 find_taken_edge_cond_expr (basic_block bb
, tree val
)
2032 edge true_edge
, false_edge
;
2034 extract_true_false_edges_from_block (bb
, &true_edge
, &false_edge
);
2036 /* If both edges of the branch lead to the same basic block, it doesn't
2037 matter which edge is taken. */
2038 if (true_edge
->dest
== false_edge
->dest
)
2041 /* Otherwise, try to determine which branch of the if() will be taken.
2042 If VAL is a constant but it can't be reduced to a 0 or a 1, then
2043 we don't really know which edge will be taken at runtime. This
2044 may happen when comparing addresses (e.g., if (&var1 == 4)). */
2045 if (integer_nonzerop (val
))
2047 else if (integer_zerop (val
))
2054 /* Given a constant value VAL and the entry block BB to a SWITCH_EXPR
2055 statement, determine which edge will be taken out of the block. Return
2056 NULL if any edge may be taken. */
2059 find_taken_edge_switch_expr (basic_block bb
, tree val
)
2061 tree switch_expr
, taken_case
;
2062 basic_block dest_bb
;
2065 if (TREE_CODE (val
) != INTEGER_CST
)
2068 switch_expr
= last_stmt (bb
);
2069 taken_case
= find_case_label_for_value (switch_expr
, val
);
2070 dest_bb
= label_to_block (CASE_LABEL (taken_case
));
2072 e
= find_edge (bb
, dest_bb
);
2079 /* Return the CASE_LABEL_EXPR that SWITCH_EXPR will take for VAL.
2080 We can make optimal use here of the fact that the case labels are
2081 sorted: We can do a binary search for a case matching VAL. */
2084 find_case_label_for_value (tree switch_expr
, tree val
)
2086 tree vec
= SWITCH_LABELS (switch_expr
);
2087 size_t low
, high
, n
= TREE_VEC_LENGTH (vec
);
2088 tree default_case
= TREE_VEC_ELT (vec
, n
- 1);
2090 for (low
= -1, high
= n
- 1; high
- low
> 1; )
2092 size_t i
= (high
+ low
) / 2;
2093 tree t
= TREE_VEC_ELT (vec
, i
);
2096 /* Cache the result of comparing CASE_LOW and val. */
2097 cmp
= tree_int_cst_compare (CASE_LOW (t
), val
);
2104 if (CASE_HIGH (t
) == NULL
)
2106 /* A singe-valued case label. */
2112 /* A case range. We can only handle integer ranges. */
2113 if (cmp
<= 0 && tree_int_cst_compare (CASE_HIGH (t
), val
) >= 0)
2118 return default_case
;
2122 /* If all the PHI nodes in DEST have alternatives for E1 and E2 and
2123 those alternatives are equal in each of the PHI nodes, then return
2124 true, else return false. */
2127 phi_alternatives_equal (basic_block dest
, edge e1
, edge e2
)
2129 tree phi
, val1
, val2
;
2132 for (phi
= phi_nodes (dest
); phi
; phi
= PHI_CHAIN (phi
))
2134 n1
= phi_arg_from_edge (phi
, e1
);
2135 n2
= phi_arg_from_edge (phi
, e2
);
2137 #ifdef ENABLE_CHECKING
2138 if (n1
< 0 || n2
< 0)
2142 val1
= PHI_ARG_DEF (phi
, n1
);
2143 val2
= PHI_ARG_DEF (phi
, n2
);
2145 if (!operand_equal_p (val1
, val2
, 0))
2153 /* Computing the Dominance Frontier:
2155 As described in Morgan, section 3.5, this may be done simply by
2156 walking the dominator tree bottom-up, computing the frontier for
2157 the children before the parent. When considering a block B,
2158 there are two cases:
2160 (1) A flow graph edge leaving B that does not lead to a child
2161 of B in the dominator tree must be a block that is either equal
2162 to B or not dominated by B. Such blocks belong in the frontier
2165 (2) Consider a block X in the frontier of one of the children C
2166 of B. If X is not equal to B and is not dominated by B, it
2167 is in the frontier of B. */
2170 compute_dominance_frontiers_1 (bitmap
*frontiers
, basic_block bb
, sbitmap done
)
2175 SET_BIT (done
, bb
->index
);
2177 /* Do the frontier of the children first. Not all children in the
2178 dominator tree (blocks dominated by this one) are children in the
2179 CFG, so check all blocks. */
2180 for (c
= first_dom_son (CDI_DOMINATORS
, bb
);
2182 c
= next_dom_son (CDI_DOMINATORS
, c
))
2184 if (! TEST_BIT (done
, c
->index
))
2185 compute_dominance_frontiers_1 (frontiers
, c
, done
);
2188 /* Find blocks conforming to rule (1) above. */
2189 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
2191 if (e
->dest
== EXIT_BLOCK_PTR
)
2193 if (get_immediate_dominator (CDI_DOMINATORS
, e
->dest
) != bb
)
2194 bitmap_set_bit (frontiers
[bb
->index
], e
->dest
->index
);
2197 /* Find blocks conforming to rule (2). */
2198 for (c
= first_dom_son (CDI_DOMINATORS
, bb
);
2200 c
= next_dom_son (CDI_DOMINATORS
, c
))
2204 EXECUTE_IF_SET_IN_BITMAP (frontiers
[c
->index
], 0, x
,
2206 if (get_immediate_dominator (CDI_DOMINATORS
, BASIC_BLOCK (x
)) != bb
)
2207 bitmap_set_bit (frontiers
[bb
->index
], x
);
2214 compute_dominance_frontiers (bitmap
*frontiers
)
2216 sbitmap done
= sbitmap_alloc (last_basic_block
);
2218 timevar_push (TV_DOM_FRONTIERS
);
2220 sbitmap_zero (done
);
2222 compute_dominance_frontiers_1 (frontiers
, ENTRY_BLOCK_PTR
->succ
->dest
, done
);
2224 sbitmap_free (done
);
2226 timevar_pop (TV_DOM_FRONTIERS
);
2231 /*---------------------------------------------------------------------------
2233 ---------------------------------------------------------------------------*/
2235 /* Dump tree-specific information of block BB to file OUTF. */
2238 tree_dump_bb (basic_block bb
, FILE *outf
, int indent
)
2240 dump_generic_bb (outf
, bb
, indent
, TDF_VOPS
);
2244 /* Dump a basic block on stderr. */
2247 debug_tree_bb (basic_block bb
)
2249 dump_bb (bb
, stderr
, 0);
2253 /* Dump basic block with index N on stderr. */
2256 debug_tree_bb_n (int n
)
2258 debug_tree_bb (BASIC_BLOCK (n
));
2259 return BASIC_BLOCK (n
);
2263 /* Dump the CFG on stderr.
2265 FLAGS are the same used by the tree dumping functions
2266 (see TDF_* in tree.h). */
2269 debug_tree_cfg (int flags
)
2271 dump_tree_cfg (stderr
, flags
);
2275 /* Dump the program showing basic block boundaries on the given FILE.
2277 FLAGS are the same used by the tree dumping functions (see TDF_* in
2281 dump_tree_cfg (FILE *file
, int flags
)
2283 if (flags
& TDF_DETAILS
)
2285 const char *funcname
2286 = lang_hooks
.decl_printable_name (current_function_decl
, 2);
2289 fprintf (file
, ";; Function %s\n\n", funcname
);
2290 fprintf (file
, ";; \n%d basic blocks, %d edges, last basic block %d.\n\n",
2291 n_basic_blocks
, n_edges
, last_basic_block
);
2293 brief_dump_cfg (file
);
2294 fprintf (file
, "\n");
2297 if (flags
& TDF_STATS
)
2298 dump_cfg_stats (file
);
2300 dump_function_to_file (current_function_decl
, file
, flags
| TDF_BLOCKS
);
2304 /* Dump CFG statistics on FILE. */
2307 dump_cfg_stats (FILE *file
)
2309 static long max_num_merged_labels
= 0;
2310 unsigned long size
, total
= 0;
2313 const char * const fmt_str
= "%-30s%-13s%12s\n";
2314 const char * const fmt_str_1
= "%-30s%13d%11lu%c\n";
2315 const char * const fmt_str_3
= "%-43s%11lu%c\n";
2316 const char *funcname
2317 = lang_hooks
.decl_printable_name (current_function_decl
, 2);
2320 fprintf (file
, "\nCFG Statistics for %s\n\n", funcname
);
2322 fprintf (file
, "---------------------------------------------------------\n");
2323 fprintf (file
, fmt_str
, "", " Number of ", "Memory");
2324 fprintf (file
, fmt_str
, "", " instances ", "used ");
2325 fprintf (file
, "---------------------------------------------------------\n");
2327 size
= n_basic_blocks
* sizeof (struct basic_block_def
);
2329 fprintf (file
, fmt_str_1
, "Basic blocks", n_basic_blocks
,
2330 SCALE (size
), LABEL (size
));
2336 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
2339 size
= n_edges
* sizeof (struct edge_def
);
2341 fprintf (file
, fmt_str_1
, "Edges", n_edges
, SCALE (size
), LABEL (size
));
2343 size
= n_basic_blocks
* sizeof (struct bb_ann_d
);
2345 fprintf (file
, fmt_str_1
, "Basic block annotations", n_basic_blocks
,
2346 SCALE (size
), LABEL (size
));
2348 fprintf (file
, "---------------------------------------------------------\n");
2349 fprintf (file
, fmt_str_3
, "Total memory used by CFG data", SCALE (total
),
2351 fprintf (file
, "---------------------------------------------------------\n");
2352 fprintf (file
, "\n");
2354 if (cfg_stats
.num_merged_labels
> max_num_merged_labels
)
2355 max_num_merged_labels
= cfg_stats
.num_merged_labels
;
2357 fprintf (file
, "Coalesced label blocks: %ld (Max so far: %ld)\n",
2358 cfg_stats
.num_merged_labels
, max_num_merged_labels
);
2360 fprintf (file
, "\n");
2364 /* Dump CFG statistics on stderr. Keep extern so that it's always
2365 linked in the final executable. */
2368 debug_cfg_stats (void)
2370 dump_cfg_stats (stderr
);
2374 /* Dump the flowgraph to a .vcg FILE. */
2377 tree_cfg2vcg (FILE *file
)
2381 const char *funcname
2382 = lang_hooks
.decl_printable_name (current_function_decl
, 2);
2384 /* Write the file header. */
2385 fprintf (file
, "graph: { title: \"%s\"\n", funcname
);
2386 fprintf (file
, "node: { title: \"ENTRY\" label: \"ENTRY\" }\n");
2387 fprintf (file
, "node: { title: \"EXIT\" label: \"EXIT\" }\n");
2389 /* Write blocks and edges. */
2390 for (e
= ENTRY_BLOCK_PTR
->succ
; e
; e
= e
->succ_next
)
2392 fprintf (file
, "edge: { sourcename: \"ENTRY\" targetname: \"%d\"",
2395 if (e
->flags
& EDGE_FAKE
)
2396 fprintf (file
, " linestyle: dotted priority: 10");
2398 fprintf (file
, " linestyle: solid priority: 100");
2400 fprintf (file
, " }\n");
2406 enum tree_code head_code
, end_code
;
2407 const char *head_name
, *end_name
;
2410 tree first
= first_stmt (bb
);
2411 tree last
= last_stmt (bb
);
2415 head_code
= TREE_CODE (first
);
2416 head_name
= tree_code_name
[head_code
];
2417 head_line
= get_lineno (first
);
2420 head_name
= "no-statement";
2424 end_code
= TREE_CODE (last
);
2425 end_name
= tree_code_name
[end_code
];
2426 end_line
= get_lineno (last
);
2429 end_name
= "no-statement";
2431 fprintf (file
, "node: { title: \"%d\" label: \"#%d\\n%s (%d)\\n%s (%d)\"}\n",
2432 bb
->index
, bb
->index
, head_name
, head_line
, end_name
,
2435 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
2437 if (e
->dest
== EXIT_BLOCK_PTR
)
2438 fprintf (file
, "edge: { sourcename: \"%d\" targetname: \"EXIT\"", bb
->index
);
2440 fprintf (file
, "edge: { sourcename: \"%d\" targetname: \"%d\"", bb
->index
, e
->dest
->index
);
2442 if (e
->flags
& EDGE_FAKE
)
2443 fprintf (file
, " priority: 10 linestyle: dotted");
2445 fprintf (file
, " priority: 100 linestyle: solid");
2447 fprintf (file
, " }\n");
2450 if (bb
->next_bb
!= EXIT_BLOCK_PTR
)
2454 fputs ("}\n\n", file
);
2459 /*---------------------------------------------------------------------------
2460 Miscellaneous helpers
2461 ---------------------------------------------------------------------------*/
2463 /* Return true if T represents a stmt that always transfers control. */
2466 is_ctrl_stmt (tree t
)
2468 return (TREE_CODE (t
) == COND_EXPR
2469 || TREE_CODE (t
) == SWITCH_EXPR
2470 || TREE_CODE (t
) == GOTO_EXPR
2471 || TREE_CODE (t
) == RETURN_EXPR
2472 || TREE_CODE (t
) == RESX_EXPR
);
2476 /* Return true if T is a statement that may alter the flow of control
2477 (e.g., a call to a non-returning function). */
2480 is_ctrl_altering_stmt (tree t
)
2484 #if defined ENABLE_CHECKING
2489 call
= get_call_expr_in (t
);
2492 /* A non-pure/const CALL_EXPR alters flow control if the current
2493 function has nonlocal labels. */
2494 if (TREE_SIDE_EFFECTS (call
) && current_function_has_nonlocal_label
)
2497 /* A CALL_EXPR also alters control flow if it does not return. */
2498 if (call_expr_flags (call
) & (ECF_NORETURN
| ECF_LONGJMP
))
2502 /* If a statement can throw, it alters control flow. */
2503 return tree_can_throw_internal (t
);
2507 /* Return true if T is a computed goto. */
2510 computed_goto_p (tree t
)
2512 return (TREE_CODE (t
) == GOTO_EXPR
2513 && TREE_CODE (GOTO_DESTINATION (t
)) != LABEL_DECL
);
2517 /* Checks whether EXPR is a simple local goto. */
2520 simple_goto_p (tree expr
)
2522 return (TREE_CODE (expr
) == GOTO_EXPR
2523 && TREE_CODE (GOTO_DESTINATION (expr
)) == LABEL_DECL
2524 && (decl_function_context (GOTO_DESTINATION (expr
))
2525 == current_function_decl
));
2529 /* Return true if T should start a new basic block. PREV_T is the
2530 statement preceding T. It is used when T is a label or a case label.
2531 Labels should only start a new basic block if their previous statement
2532 wasn't a label. Otherwise, sequence of labels would generate
2533 unnecessary basic blocks that only contain a single label. */
2536 stmt_starts_bb_p (tree t
, tree prev_t
)
2538 enum tree_code code
;
2543 /* LABEL_EXPRs start a new basic block only if the preceding
2544 statement wasn't a label of the same type. This prevents the
2545 creation of consecutive blocks that have nothing but a single
2547 code
= TREE_CODE (t
);
2548 if (code
== LABEL_EXPR
)
2550 /* Nonlocal and computed GOTO targets always start a new block. */
2551 if (code
== LABEL_EXPR
2552 && (DECL_NONLOCAL (LABEL_EXPR_LABEL (t
))
2553 || FORCED_LABEL (LABEL_EXPR_LABEL (t
))))
2556 if (prev_t
&& TREE_CODE (prev_t
) == code
)
2558 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (prev_t
)))
2561 cfg_stats
.num_merged_labels
++;
2572 /* Return true if T should end a basic block. */
2575 stmt_ends_bb_p (tree t
)
2577 return is_ctrl_stmt (t
) || is_ctrl_altering_stmt (t
);
2581 /* Add gotos that used to be represented implicitly in the CFG. */
2584 disband_implicit_edges (void)
2587 block_stmt_iterator last
;
2593 last
= bsi_last (bb
);
2594 stmt
= last_stmt (bb
);
2596 if (stmt
&& TREE_CODE (stmt
) == COND_EXPR
)
2598 /* Remove superfluous gotos from COND_EXPR branches. Moved
2599 from cfg_remove_useless_stmts here since it violates the
2600 invariants for tree--cfg correspondence and thus fits better
2601 here where we do it anyway. */
2602 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
2604 if (e
->dest
!= bb
->next_bb
)
2607 if (e
->flags
& EDGE_TRUE_VALUE
)
2608 COND_EXPR_THEN (stmt
) = build_empty_stmt ();
2609 else if (e
->flags
& EDGE_FALSE_VALUE
)
2610 COND_EXPR_ELSE (stmt
) = build_empty_stmt ();
2613 e
->flags
|= EDGE_FALLTHRU
;
2619 if (stmt
&& TREE_CODE (stmt
) == RETURN_EXPR
)
2621 /* Remove the RETURN_EXPR if we may fall though to the exit
2624 || bb
->succ
->succ_next
2625 || bb
->succ
->dest
!= EXIT_BLOCK_PTR
)
2628 if (bb
->next_bb
== EXIT_BLOCK_PTR
2629 && !TREE_OPERAND (stmt
, 0))
2632 bb
->succ
->flags
|= EDGE_FALLTHRU
;
2637 /* There can be no fallthru edge if the last statement is a control
2639 if (stmt
&& is_ctrl_stmt (stmt
))
2642 /* Find a fallthru edge and emit the goto if necessary. */
2643 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
2644 if (e
->flags
& EDGE_FALLTHRU
)
2647 if (!e
|| e
->dest
== bb
->next_bb
)
2650 if (e
->dest
== EXIT_BLOCK_PTR
)
2653 label
= tree_block_label (e
->dest
);
2655 stmt
= build1 (GOTO_EXPR
, void_type_node
, label
);
2656 #ifdef USE_MAPPED_LOCATION
2657 SET_EXPR_LOCATION (stmt
, e
->goto_locus
);
2659 SET_EXPR_LOCUS (stmt
, e
->goto_locus
);
2661 bsi_insert_after (&last
, stmt
, BSI_NEW_STMT
);
2662 e
->flags
&= ~EDGE_FALLTHRU
;
2666 /* Remove block annotations and other datastructures. */
2669 delete_tree_cfg_annotations (void)
2672 if (n_basic_blocks
> 0)
2673 free_blocks_annotations ();
2675 label_to_block_map
= NULL
;
2682 /* Return the first statement in basic block BB. */
2685 first_stmt (basic_block bb
)
2687 block_stmt_iterator i
= bsi_start (bb
);
2688 return !bsi_end_p (i
) ? bsi_stmt (i
) : NULL_TREE
;
2692 /* Return the last statement in basic block BB. */
2695 last_stmt (basic_block bb
)
2697 block_stmt_iterator b
= bsi_last (bb
);
2698 return !bsi_end_p (b
) ? bsi_stmt (b
) : NULL_TREE
;
2702 /* Return a pointer to the last statement in block BB. */
2705 last_stmt_ptr (basic_block bb
)
2707 block_stmt_iterator last
= bsi_last (bb
);
2708 return !bsi_end_p (last
) ? bsi_stmt_ptr (last
) : NULL
;
2712 /* Return the last statement of an otherwise empty block. Return NULL
2713 if the block is totally empty, or if it contains more than one
2717 last_and_only_stmt (basic_block bb
)
2719 block_stmt_iterator i
= bsi_last (bb
);
2725 last
= bsi_stmt (i
);
2730 /* Empty statements should no longer appear in the instruction stream.
2731 Everything that might have appeared before should be deleted by
2732 remove_useless_stmts, and the optimizers should just bsi_remove
2733 instead of smashing with build_empty_stmt.
2735 Thus the only thing that should appear here in a block containing
2736 one executable statement is a label. */
2737 prev
= bsi_stmt (i
);
2738 if (TREE_CODE (prev
) == LABEL_EXPR
)
2745 /* Mark BB as the basic block holding statement T. */
2748 set_bb_for_stmt (tree t
, basic_block bb
)
2750 if (TREE_CODE (t
) == STATEMENT_LIST
)
2752 tree_stmt_iterator i
;
2753 for (i
= tsi_start (t
); !tsi_end_p (i
); tsi_next (&i
))
2754 set_bb_for_stmt (tsi_stmt (i
), bb
);
2758 stmt_ann_t ann
= get_stmt_ann (t
);
2761 /* If the statement is a label, add the label to block-to-labels map
2762 so that we can speed up edge creation for GOTO_EXPRs. */
2763 if (TREE_CODE (t
) == LABEL_EXPR
)
2767 t
= LABEL_EXPR_LABEL (t
);
2768 uid
= LABEL_DECL_UID (t
);
2771 LABEL_DECL_UID (t
) = uid
= cfun
->last_label_uid
++;
2772 if (VARRAY_SIZE (label_to_block_map
) <= (unsigned) uid
)
2773 VARRAY_GROW (label_to_block_map
, 3 * uid
/ 2);
2777 #ifdef ENABLE_CHECKING
2778 /* We're moving an existing label. Make sure that we've
2779 removed it from the old block. */
2780 if (bb
&& VARRAY_BB (label_to_block_map
, uid
))
2784 VARRAY_BB (label_to_block_map
, uid
) = bb
;
2790 /* Insert statement (or statement list) T before the statement
2791 pointed-to by iterator I. M specifies how to update iterator I
2792 after insertion (see enum bsi_iterator_update). */
2795 bsi_insert_before (block_stmt_iterator
*i
, tree t
, enum bsi_iterator_update m
)
2797 set_bb_for_stmt (t
, i
->bb
);
2799 tsi_link_before (&i
->tsi
, t
, m
);
2803 /* Insert statement (or statement list) T after the statement
2804 pointed-to by iterator I. M specifies how to update iterator I
2805 after insertion (see enum bsi_iterator_update). */
2808 bsi_insert_after (block_stmt_iterator
*i
, tree t
, enum bsi_iterator_update m
)
2810 set_bb_for_stmt (t
, i
->bb
);
2812 tsi_link_after (&i
->tsi
, t
, m
);
2816 /* Remove the statement pointed to by iterator I. The iterator is updated
2817 to the next statement. */
2820 bsi_remove (block_stmt_iterator
*i
)
2822 tree t
= bsi_stmt (*i
);
2823 set_bb_for_stmt (t
, NULL
);
2825 tsi_delink (&i
->tsi
);
2829 /* Move the statement at FROM so it comes right after the statement at TO. */
2832 bsi_move_after (block_stmt_iterator
*from
, block_stmt_iterator
*to
)
2834 tree stmt
= bsi_stmt (*from
);
2836 bsi_insert_after (to
, stmt
, BSI_SAME_STMT
);
2840 /* Move the statement at FROM so it comes right before the statement at TO. */
2843 bsi_move_before (block_stmt_iterator
*from
, block_stmt_iterator
*to
)
2845 tree stmt
= bsi_stmt (*from
);
2847 bsi_insert_before (to
, stmt
, BSI_SAME_STMT
);
2851 /* Move the statement at FROM to the end of basic block BB. */
2854 bsi_move_to_bb_end (block_stmt_iterator
*from
, basic_block bb
)
2856 block_stmt_iterator last
= bsi_last (bb
);
2858 /* Have to check bsi_end_p because it could be an empty block. */
2859 if (!bsi_end_p (last
) && is_ctrl_stmt (bsi_stmt (last
)))
2860 bsi_move_before (from
, &last
);
2862 bsi_move_after (from
, &last
);
2866 /* Replace the contents of the statement pointed to by iterator BSI
2867 with STMT. If PRESERVE_EH_INFO is true, the exception handling
2868 information of the original statement is preserved. */
2871 bsi_replace (const block_stmt_iterator
*bsi
, tree stmt
, bool preserve_eh_info
)
2874 tree orig_stmt
= bsi_stmt (*bsi
);
2876 SET_EXPR_LOCUS (stmt
, EXPR_LOCUS (orig_stmt
));
2877 set_bb_for_stmt (stmt
, bsi
->bb
);
2879 /* Preserve EH region information from the original statement, if
2880 requested by the caller. */
2881 if (preserve_eh_info
)
2883 eh_region
= lookup_stmt_eh_region (orig_stmt
);
2885 add_stmt_to_eh_region (stmt
, eh_region
);
2888 *bsi_stmt_ptr (*bsi
) = stmt
;
2893 /* Insert the statement pointed-to by BSI into edge E. Every attempt
2894 is made to place the statement in an existing basic block, but
2895 sometimes that isn't possible. When it isn't possible, the edge is
2896 split and the statement is added to the new block.
2898 In all cases, the returned *BSI points to the correct location. The
2899 return value is true if insertion should be done after the location,
2900 or false if it should be done before the location. */
2903 tree_find_edge_insert_loc (edge e
, block_stmt_iterator
*bsi
)
2905 basic_block dest
, src
;
2911 /* If the destination has one predecessor which has no PHI nodes,
2912 insert there. Except for the exit block.
2914 The requirement for no PHI nodes could be relaxed. Basically we
2915 would have to examine the PHIs to prove that none of them used
2916 the value set by the statement we want to insert on E. That
2917 hardly seems worth the effort. */
2918 if (dest
->pred
->pred_next
== NULL
2919 && ! phi_nodes (dest
)
2920 && dest
!= EXIT_BLOCK_PTR
)
2922 *bsi
= bsi_start (dest
);
2923 if (bsi_end_p (*bsi
))
2926 /* Make sure we insert after any leading labels. */
2927 tmp
= bsi_stmt (*bsi
);
2928 while (TREE_CODE (tmp
) == LABEL_EXPR
)
2931 if (bsi_end_p (*bsi
))
2933 tmp
= bsi_stmt (*bsi
);
2936 if (bsi_end_p (*bsi
))
2938 *bsi
= bsi_last (dest
);
2945 /* If the source has one successor, the edge is not abnormal and
2946 the last statement does not end a basic block, insert there.
2947 Except for the entry block. */
2949 if ((e
->flags
& EDGE_ABNORMAL
) == 0
2950 && src
->succ
->succ_next
== NULL
2951 && src
!= ENTRY_BLOCK_PTR
)
2953 *bsi
= bsi_last (src
);
2954 if (bsi_end_p (*bsi
))
2957 tmp
= bsi_stmt (*bsi
);
2958 if (!stmt_ends_bb_p (tmp
))
2961 /* Insert code just before returning the value. We may need to decompose
2962 the return in the case it contains non-trivial operand. */
2963 if (TREE_CODE (tmp
) == RETURN_EXPR
)
2965 tree op
= TREE_OPERAND (tmp
, 0);
2966 if (!is_gimple_val (op
))
2968 if (TREE_CODE (op
) != MODIFY_EXPR
)
2970 bsi_insert_before (bsi
, op
, BSI_NEW_STMT
);
2971 TREE_OPERAND (tmp
, 0) = TREE_OPERAND (op
, 0);
2978 /* Otherwise, create a new basic block, and split this edge. */
2979 dest
= split_edge (e
);
2985 /* This routine will commit all pending edge insertions, creating any new
2986 basic blocks which are necessary.
2988 If specified, NEW_BLOCKS returns a count of the number of new basic
2989 blocks which were created. */
2992 bsi_commit_edge_inserts (int *new_blocks
)
2998 blocks
= n_basic_blocks
;
3000 bsi_commit_edge_inserts_1 (ENTRY_BLOCK_PTR
->succ
);
3003 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
3004 bsi_commit_edge_inserts_1 (e
);
3007 *new_blocks
= n_basic_blocks
- blocks
;
3011 /* Commit insertions pending at edge E. */
3014 bsi_commit_edge_inserts_1 (edge e
)
3016 if (PENDING_STMT (e
))
3018 block_stmt_iterator bsi
;
3019 tree stmt
= PENDING_STMT (e
);
3021 PENDING_STMT (e
) = NULL_TREE
;
3023 if (tree_find_edge_insert_loc (e
, &bsi
))
3024 bsi_insert_after (&bsi
, stmt
, BSI_NEW_STMT
);
3026 bsi_insert_before (&bsi
, stmt
, BSI_NEW_STMT
);
3031 /* Add STMT to the pending list of edge E. No actual insertion is
3032 made until a call to bsi_commit_edge_inserts () is made. */
3035 bsi_insert_on_edge (edge e
, tree stmt
)
3037 append_to_statement_list (stmt
, &PENDING_STMT (e
));
3041 /*---------------------------------------------------------------------------
3042 Tree specific functions for CFG manipulation
3043 ---------------------------------------------------------------------------*/
3045 /* Split a (typically critical) edge EDGE_IN. Return the new block.
3046 Abort on abnormal edges. */
3049 tree_split_edge (edge edge_in
)
3051 basic_block new_bb
, after_bb
, dest
, src
;
3056 /* Abnormal edges cannot be split. */
3057 if (edge_in
->flags
& EDGE_ABNORMAL
)
3061 dest
= edge_in
->dest
;
3063 /* Place the new block in the block list. Try to keep the new block
3064 near its "logical" location. This is of most help to humans looking
3065 at debugging dumps. */
3066 for (e
= dest
->pred
; e
; e
= e
->pred_next
)
3067 if (e
->src
->next_bb
== dest
)
3070 after_bb
= dest
->prev_bb
;
3072 after_bb
= edge_in
->src
;
3074 new_bb
= create_empty_bb (after_bb
);
3075 new_edge
= make_edge (new_bb
, dest
, EDGE_FALLTHRU
);
3077 /* Find all the PHI arguments on the original edge, and change them to
3078 the new edge. Do it before redirection, so that the argument does not
3080 for (phi
= phi_nodes (dest
); phi
; phi
= PHI_CHAIN (phi
))
3082 num_elem
= PHI_NUM_ARGS (phi
);
3083 for (i
= 0; i
< num_elem
; i
++)
3084 if (PHI_ARG_EDGE (phi
, i
) == edge_in
)
3086 PHI_ARG_EDGE (phi
, i
) = new_edge
;
3091 if (!redirect_edge_and_branch (edge_in
, new_bb
))
3094 if (PENDING_STMT (edge_in
))
3101 /* Return true when BB has label LABEL in it. */
3104 has_label_p (basic_block bb
, tree label
)
3106 block_stmt_iterator bsi
;
3108 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
3110 tree stmt
= bsi_stmt (bsi
);
3112 if (TREE_CODE (stmt
) != LABEL_EXPR
)
3114 if (LABEL_EXPR_LABEL (stmt
) == label
)
3121 /* Callback for walk_tree, check that all elements with address taken are
3122 properly noticed as such. */
3125 verify_expr (tree
*tp
, int *walk_subtrees
, void *data ATTRIBUTE_UNUSED
)
3132 /* Check operand N for being valid GIMPLE and give error MSG if not.
3133 We check for constants explicitly since they are not considered
3134 gimple invariants if they overflowed. */
3135 #define CHECK_OP(N, MSG) \
3136 do { if (TREE_CODE_CLASS (TREE_CODE (TREE_OPERAND (t, N))) != 'c' \
3137 && !is_gimple_val (TREE_OPERAND (t, N))) \
3138 { error (MSG); return TREE_OPERAND (t, N); }} while (0)
3140 switch (TREE_CODE (t
))
3143 if (SSA_NAME_IN_FREE_LIST (t
))
3145 error ("SSA name in freelist but still referenced");
3151 x
= TREE_OPERAND (t
, 0);
3152 if (TREE_CODE (x
) == BIT_FIELD_REF
3153 && is_gimple_reg (TREE_OPERAND (x
, 0)))
3155 error ("GIMPLE register modified with BIT_FIELD_REF");
3161 /* Skip any references (they will be checked when we recurse down the
3162 tree) and ensure that any variable used as a prefix is marked
3164 for (x
= TREE_OPERAND (t
, 0);
3165 (handled_component_p (x
)
3166 || TREE_CODE (x
) == REALPART_EXPR
3167 || TREE_CODE (x
) == IMAGPART_EXPR
);
3168 x
= TREE_OPERAND (x
, 0))
3171 if (TREE_CODE (x
) != VAR_DECL
&& TREE_CODE (x
) != PARM_DECL
)
3173 if (!TREE_ADDRESSABLE (x
))
3175 error ("address taken, but ADDRESSABLE bit not set");
3181 x
= TREE_OPERAND (t
, 0);
3182 if (TREE_CODE (TREE_TYPE (x
)) != BOOLEAN_TYPE
)
3184 error ("non-boolean used in condition");
3191 case FIX_TRUNC_EXPR
:
3193 case FIX_FLOOR_EXPR
:
3194 case FIX_ROUND_EXPR
:
3199 case NON_LVALUE_EXPR
:
3200 case TRUTH_NOT_EXPR
:
3201 CHECK_OP (0, "Invalid operand to unary operator");
3208 case ARRAY_RANGE_REF
:
3210 case VIEW_CONVERT_EXPR
:
3211 /* We have a nest of references. Verify that each of the operands
3212 that determine where to reference is either a constant or a variable,
3213 verify that the base is valid, and then show we've already checked
3215 while (TREE_CODE (t
) == REALPART_EXPR
|| TREE_CODE (t
) == IMAGPART_EXPR
3216 || handled_component_p (t
))
3218 if (TREE_CODE (t
) == COMPONENT_REF
&& TREE_OPERAND (t
, 2))
3219 CHECK_OP (2, "Invalid COMPONENT_REF offset operator");
3220 else if (TREE_CODE (t
) == ARRAY_REF
3221 || TREE_CODE (t
) == ARRAY_RANGE_REF
)
3223 CHECK_OP (1, "Invalid array index.");
3224 if (TREE_OPERAND (t
, 2))
3225 CHECK_OP (2, "Invalid array lower bound.");
3226 if (TREE_OPERAND (t
, 3))
3227 CHECK_OP (3, "Invalid array stride.");
3229 else if (TREE_CODE (t
) == BIT_FIELD_REF
)
3231 CHECK_OP (1, "Invalid operand to BIT_FIELD_REF");
3232 CHECK_OP (2, "Invalid operand to BIT_FIELD_REF");
3235 t
= TREE_OPERAND (t
, 0);
3238 if (TREE_CODE_CLASS (TREE_CODE (t
)) != 'c'
3239 && !is_gimple_lvalue (t
))
3241 error ("Invalid reference prefix.");
3253 case UNORDERED_EXPR
:
3264 case TRUNC_DIV_EXPR
:
3266 case FLOOR_DIV_EXPR
:
3267 case ROUND_DIV_EXPR
:
3268 case TRUNC_MOD_EXPR
:
3270 case FLOOR_MOD_EXPR
:
3271 case ROUND_MOD_EXPR
:
3273 case EXACT_DIV_EXPR
:
3283 CHECK_OP (0, "Invalid operand to binary operator");
3284 CHECK_OP (1, "Invalid operand to binary operator");
3296 /* Verify STMT, return true if STMT is not in GIMPLE form.
3297 TODO: Implement type checking. */
3300 verify_stmt (tree stmt
, bool last_in_block
)
3304 if (!is_gimple_stmt (stmt
))
3306 error ("Is not a valid GIMPLE statement.");
3310 addr
= walk_tree (&stmt
, verify_expr
, NULL
, NULL
);
3313 debug_generic_stmt (addr
);
3317 /* If the statement is marked as part of an EH region, then it is
3318 expected that the statement could throw. Verify that when we
3319 have optimizations that simplify statements such that we prove
3320 that they cannot throw, that we update other data structures
3322 if (lookup_stmt_eh_region (stmt
) >= 0)
3324 if (!tree_could_throw_p (stmt
))
3326 error ("Statement marked for throw, but doesn't.");
3329 if (!last_in_block
&& tree_can_throw_internal (stmt
))
3331 error ("Statement marked for throw in middle of block.");
3339 debug_generic_stmt (stmt
);
3344 /* Return true when the T can be shared. */
3347 tree_node_can_be_shared (tree t
)
3349 if (TYPE_P (t
) || DECL_P (t
)
3350 /* We check for constants explicitly since they are not considered
3351 gimple invariants if they overflowed. */
3352 || TREE_CODE_CLASS (TREE_CODE (t
)) == 'c'
3353 || is_gimple_min_invariant (t
)
3354 || TREE_CODE (t
) == SSA_NAME
)
3357 while (((TREE_CODE (t
) == ARRAY_REF
|| TREE_CODE (t
) == ARRAY_RANGE_REF
)
3358 /* We check for constants explicitly since they are not considered
3359 gimple invariants if they overflowed. */
3360 && (TREE_CODE_CLASS (TREE_CODE (TREE_OPERAND (t
, 1))) == 'c'
3361 || is_gimple_min_invariant (TREE_OPERAND (t
, 1))))
3362 || (TREE_CODE (t
) == COMPONENT_REF
3363 || TREE_CODE (t
) == REALPART_EXPR
3364 || TREE_CODE (t
) == IMAGPART_EXPR
))
3365 t
= TREE_OPERAND (t
, 0);
3374 /* Called via walk_trees. Verify tree sharing. */
3377 verify_node_sharing (tree
* tp
, int *walk_subtrees
, void *data
)
3379 htab_t htab
= (htab_t
) data
;
3382 if (tree_node_can_be_shared (*tp
))
3384 *walk_subtrees
= false;
3388 slot
= htab_find_slot (htab
, *tp
, INSERT
);
3397 /* Verify the GIMPLE statement chain. */
3403 block_stmt_iterator bsi
;
3408 timevar_push (TV_TREE_STMT_VERIFY
);
3409 htab
= htab_create (37, htab_hash_pointer
, htab_eq_pointer
, NULL
);
3416 for (phi
= phi_nodes (bb
); phi
; phi
= PHI_CHAIN (phi
))
3418 int phi_num_args
= PHI_NUM_ARGS (phi
);
3420 for (i
= 0; i
< phi_num_args
; i
++)
3422 tree t
= PHI_ARG_DEF (phi
, i
);
3425 /* Addressable variables do have SSA_NAMEs but they
3426 are not considered gimple values. */
3427 if (TREE_CODE (t
) != SSA_NAME
3428 && TREE_CODE (t
) != FUNCTION_DECL
3429 && !is_gimple_val (t
))
3431 error ("PHI def is not a GIMPLE value");
3432 debug_generic_stmt (phi
);
3433 debug_generic_stmt (t
);
3437 addr
= walk_tree (&t
, verify_expr
, NULL
, NULL
);
3440 debug_generic_stmt (addr
);
3444 addr
= walk_tree (&t
, verify_node_sharing
, htab
, NULL
);
3447 error ("Incorrect sharing of tree nodes");
3448 debug_generic_stmt (phi
);
3449 debug_generic_stmt (addr
);
3455 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); )
3457 tree stmt
= bsi_stmt (bsi
);
3459 err
|= verify_stmt (stmt
, bsi_end_p (bsi
));
3460 addr
= walk_tree (&stmt
, verify_node_sharing
, htab
, NULL
);
3463 error ("Incorrect sharing of tree nodes");
3464 debug_generic_stmt (stmt
);
3465 debug_generic_stmt (addr
);
3472 internal_error ("verify_stmts failed.");
3475 timevar_pop (TV_TREE_STMT_VERIFY
);
3479 /* Verifies that the flow information is OK. */
3482 tree_verify_flow_info (void)
3486 block_stmt_iterator bsi
;
3490 if (ENTRY_BLOCK_PTR
->stmt_list
)
3492 error ("ENTRY_BLOCK has a statement list associated with it\n");
3496 if (EXIT_BLOCK_PTR
->stmt_list
)
3498 error ("EXIT_BLOCK has a statement list associated with it\n");
3502 for (e
= EXIT_BLOCK_PTR
->pred
; e
; e
= e
->pred_next
)
3503 if (e
->flags
& EDGE_FALLTHRU
)
3505 error ("Fallthru to exit from bb %d\n", e
->src
->index
);
3511 bool found_ctrl_stmt
= false;
3513 /* Skip labels on the start of basic block. */
3514 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
3516 if (TREE_CODE (bsi_stmt (bsi
)) != LABEL_EXPR
)
3519 if (label_to_block (LABEL_EXPR_LABEL (bsi_stmt (bsi
))) != bb
)
3521 error ("Label %s to block does not match in bb %d\n",
3522 IDENTIFIER_POINTER (DECL_NAME (bsi_stmt (bsi
))),
3527 if (decl_function_context (LABEL_EXPR_LABEL (bsi_stmt (bsi
)))
3528 != current_function_decl
)
3530 error ("Label %s has incorrect context in bb %d\n",
3531 IDENTIFIER_POINTER (DECL_NAME (bsi_stmt (bsi
))),
3537 /* Verify that body of basic block BB is free of control flow. */
3538 for (; !bsi_end_p (bsi
); bsi_next (&bsi
))
3540 tree stmt
= bsi_stmt (bsi
);
3542 if (found_ctrl_stmt
)
3544 error ("Control flow in the middle of basic block %d\n",
3549 if (stmt_ends_bb_p (stmt
))
3550 found_ctrl_stmt
= true;
3552 if (TREE_CODE (stmt
) == LABEL_EXPR
)
3554 error ("Label %s in the middle of basic block %d\n",
3555 IDENTIFIER_POINTER (DECL_NAME (stmt
)),
3560 bsi
= bsi_last (bb
);
3561 if (bsi_end_p (bsi
))
3564 stmt
= bsi_stmt (bsi
);
3566 if (is_ctrl_stmt (stmt
))
3568 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
3569 if (e
->flags
& EDGE_FALLTHRU
)
3571 error ("Fallthru edge after a control statement in bb %d \n",
3577 switch (TREE_CODE (stmt
))
3583 if (TREE_CODE (COND_EXPR_THEN (stmt
)) != GOTO_EXPR
3584 || TREE_CODE (COND_EXPR_ELSE (stmt
)) != GOTO_EXPR
)
3586 error ("Structured COND_EXPR at the end of bb %d\n", bb
->index
);
3590 extract_true_false_edges_from_block (bb
, &true_edge
, &false_edge
);
3592 if (!true_edge
|| !false_edge
3593 || !(true_edge
->flags
& EDGE_TRUE_VALUE
)
3594 || !(false_edge
->flags
& EDGE_FALSE_VALUE
)
3595 || (true_edge
->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
))
3596 || (false_edge
->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
))
3597 || bb
->succ
->succ_next
->succ_next
)
3599 error ("Wrong outgoing edge flags at end of bb %d\n",
3604 if (!has_label_p (true_edge
->dest
,
3605 GOTO_DESTINATION (COND_EXPR_THEN (stmt
))))
3607 error ("`then' label does not match edge at end of bb %d\n",
3612 if (!has_label_p (false_edge
->dest
,
3613 GOTO_DESTINATION (COND_EXPR_ELSE (stmt
))))
3615 error ("`else' label does not match edge at end of bb %d\n",
3623 if (simple_goto_p (stmt
))
3625 error ("Explicit goto at end of bb %d\n", bb
->index
);
3630 /* FIXME. We should double check that the labels in the
3631 destination blocks have their address taken. */
3632 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
3633 if ((e
->flags
& (EDGE_FALLTHRU
| EDGE_TRUE_VALUE
3634 | EDGE_FALSE_VALUE
))
3635 || !(e
->flags
& EDGE_ABNORMAL
))
3637 error ("Wrong outgoing edge flags at end of bb %d\n",
3645 if (!bb
->succ
|| bb
->succ
->succ_next
3646 || (bb
->succ
->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
3647 | EDGE_TRUE_VALUE
| EDGE_FALSE_VALUE
)))
3649 error ("Wrong outgoing edge flags at end of bb %d\n", bb
->index
);
3652 if (bb
->succ
->dest
!= EXIT_BLOCK_PTR
)
3654 error ("Return edge does not point to exit in bb %d\n",
3667 vec
= SWITCH_LABELS (stmt
);
3668 n
= TREE_VEC_LENGTH (vec
);
3670 /* Mark all the destination basic blocks. */
3671 for (i
= 0; i
< n
; ++i
)
3673 tree lab
= CASE_LABEL (TREE_VEC_ELT (vec
, i
));
3674 basic_block label_bb
= label_to_block (lab
);
3676 if (label_bb
->aux
&& label_bb
->aux
!= (void *)1)
3678 label_bb
->aux
= (void *)1;
3681 /* Verify that the case labels are sorted. */
3682 prev
= TREE_VEC_ELT (vec
, 0);
3683 for (i
= 1; i
< n
- 1; ++i
)
3685 tree c
= TREE_VEC_ELT (vec
, i
);
3688 error ("Found default case not at end of case vector");
3692 if (! tree_int_cst_lt (CASE_LOW (prev
), CASE_LOW (c
)))
3694 error ("Case labels not sorted:\n ");
3695 print_generic_expr (stderr
, prev
, 0);
3696 fprintf (stderr
," is greater than ");
3697 print_generic_expr (stderr
, c
, 0);
3698 fprintf (stderr
," but comes before it.\n");
3703 if (CASE_LOW (TREE_VEC_ELT (vec
, n
- 1)))
3705 error ("No default case found at end of case vector");
3709 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
3713 error ("Extra outgoing edge %d->%d\n",
3714 bb
->index
, e
->dest
->index
);
3717 e
->dest
->aux
= (void *)2;
3718 if ((e
->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
3719 | EDGE_TRUE_VALUE
| EDGE_FALSE_VALUE
)))
3721 error ("Wrong outgoing edge flags at end of bb %d\n",
3727 /* Check that we have all of them. */
3728 for (i
= 0; i
< n
; ++i
)
3730 tree lab
= CASE_LABEL (TREE_VEC_ELT (vec
, i
));
3731 basic_block label_bb
= label_to_block (lab
);
3733 if (label_bb
->aux
!= (void *)2)
3735 error ("Missing edge %i->%i\n",
3736 bb
->index
, label_bb
->index
);
3741 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
3742 e
->dest
->aux
= (void *)0;
3749 if (dom_computed
[CDI_DOMINATORS
] >= DOM_NO_FAST_QUERY
)
3750 verify_dominators (CDI_DOMINATORS
);
3756 /* Updates phi nodes after creating forwarder block joined
3757 by edge FALLTHRU. */
3760 tree_make_forwarder_block (edge fallthru
)
3763 basic_block dummy
, bb
;
3764 tree phi
, new_phi
, var
, prev
, next
;
3766 dummy
= fallthru
->src
;
3767 bb
= fallthru
->dest
;
3769 if (!bb
->pred
->pred_next
)
3772 /* If we redirected a branch we must create new phi nodes at the
3774 for (phi
= phi_nodes (dummy
); phi
; phi
= PHI_CHAIN (phi
))
3776 var
= PHI_RESULT (phi
);
3777 new_phi
= create_phi_node (var
, bb
);
3778 SSA_NAME_DEF_STMT (var
) = new_phi
;
3779 SET_PHI_RESULT (phi
, make_ssa_name (SSA_NAME_VAR (var
), phi
));
3780 add_phi_arg (&new_phi
, PHI_RESULT (phi
), fallthru
);
3783 /* Ensure that the PHI node chain is in the same order. */
3785 for (phi
= phi_nodes (bb
); phi
; phi
= next
)
3787 next
= PHI_CHAIN (phi
);
3788 PHI_CHAIN (phi
) = prev
;
3791 set_phi_nodes (bb
, prev
);
3793 /* Add the arguments we have stored on edges. */
3794 for (e
= bb
->pred
; e
; e
= e
->pred_next
)
3799 for (phi
= phi_nodes (bb
), var
= PENDING_STMT (e
);
3801 phi
= PHI_CHAIN (phi
), var
= TREE_CHAIN (var
))
3802 add_phi_arg (&phi
, TREE_VALUE (var
), e
);
3804 PENDING_STMT (e
) = NULL
;
3809 /* Return true if basic block BB does nothing except pass control
3810 flow to another block and that we can safely insert a label at
3811 the start of the successor block. */
3814 tree_forwarder_block_p (basic_block bb
)
3816 block_stmt_iterator bsi
;
3819 /* If we have already determined that this block is not forwardable,
3820 then no further checks are necessary. */
3821 if (! bb_ann (bb
)->forwardable
)
3824 /* BB must have a single outgoing normal edge. Otherwise it can not be
3825 a forwarder block. */
3827 || bb
->succ
->succ_next
3828 || bb
->succ
->dest
== EXIT_BLOCK_PTR
3829 || (bb
->succ
->flags
& EDGE_ABNORMAL
)
3830 || bb
== ENTRY_BLOCK_PTR
)
3832 bb_ann (bb
)->forwardable
= 0;
3836 /* Successors of the entry block are not forwarders. */
3837 for (e
= ENTRY_BLOCK_PTR
->succ
; e
; e
= e
->succ_next
)
3840 bb_ann (bb
)->forwardable
= 0;
3844 /* BB can not have any PHI nodes. This could potentially be relaxed
3845 early in compilation if we re-rewrote the variables appearing in
3846 any PHI nodes in forwarder blocks. */
3849 bb_ann (bb
)->forwardable
= 0;
3853 /* Now walk through the statements. We can ignore labels, anything else
3854 means this is not a forwarder block. */
3855 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
3857 tree stmt
= bsi_stmt (bsi
);
3859 switch (TREE_CODE (stmt
))
3862 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt
)))
3867 bb_ann (bb
)->forwardable
= 0;
3876 /* Thread jumps over empty statements.
3878 This code should _not_ thread over obviously equivalent conditions
3879 as that requires nontrivial updates to the SSA graph. */
3884 edge e
, next
, last
, old
;
3885 basic_block bb
, dest
, tmp
;
3888 bool retval
= false;
3891 bb_ann (bb
)->forwardable
= 1;
3893 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
, EXIT_BLOCK_PTR
, next_bb
)
3895 /* Don't waste time on unreachable blocks. */
3899 /* Nor on forwarders. */
3900 if (tree_forwarder_block_p (bb
))
3903 /* This block is now part of a forwarding path, mark it as not
3904 forwardable so that we can detect loops. This bit will be
3906 bb_ann (bb
)->forwardable
= 0;
3908 /* Examine each of our block's successors to see if it is
3910 for (e
= bb
->succ
; e
; e
= next
)
3912 next
= e
->succ_next
;
3914 /* If the edge is abnormal or its destination is not
3915 forwardable, then there's nothing to do. */
3916 if ((e
->flags
& EDGE_ABNORMAL
)
3917 || !tree_forwarder_block_p (e
->dest
))
3920 /* Now walk through as many forwarder block as possible to
3921 find the ultimate destination we want to thread our jump
3923 last
= e
->dest
->succ
;
3924 bb_ann (e
->dest
)->forwardable
= 0;
3925 for (dest
= e
->dest
->succ
->dest
;
3926 tree_forwarder_block_p (dest
);
3928 dest
= dest
->succ
->dest
)
3930 /* An infinite loop detected. We redirect the edge anyway, so
3931 that the loop is shrunk into single basic block. */
3932 if (!bb_ann (dest
)->forwardable
)
3935 if (dest
->succ
->dest
== EXIT_BLOCK_PTR
)
3938 bb_ann (dest
)->forwardable
= 0;
3941 /* Reset the forwardable marks to 1. */
3944 tmp
= tmp
->succ
->dest
)
3945 bb_ann (tmp
)->forwardable
= 1;
3947 if (dest
== e
->dest
)
3950 old
= find_edge (bb
, dest
);
3953 /* If there already is an edge, check whether the values
3954 in phi nodes differ. */
3955 if (!phi_alternatives_equal (dest
, last
, old
))
3957 /* The previous block is forwarder. Redirect our jump
3958 to that target instead since we know it has no PHI
3959 nodes that will need updating. */
3962 /* That might mean that no forwarding at all is possible. */
3963 if (dest
== e
->dest
)
3966 old
= find_edge (bb
, dest
);
3970 /* Perform the redirection. */
3972 e
= redirect_edge_and_branch (e
, dest
);
3974 /* TODO -- updating dominators in this case is simple. */
3975 free_dominance_info (CDI_DOMINATORS
);
3979 /* Update PHI nodes. We know that the new argument should
3980 have the same value as the argument associated with LAST.
3981 Otherwise we would have changed our target block above. */
3982 for (phi
= phi_nodes (dest
); phi
; phi
= PHI_CHAIN (phi
))
3984 arg
= phi_arg_from_edge (phi
, last
);
3987 add_phi_arg (&phi
, PHI_ARG_DEF (phi
, arg
), e
);
3992 /* Reset the forwardable bit on our block since it's no longer in
3993 a forwarding chain path. */
3994 bb_ann (bb
)->forwardable
= 1;
4001 /* Return a non-special label in the head of basic block BLOCK.
4002 Create one if it doesn't exist. */
4005 tree_block_label (basic_block bb
)
4007 block_stmt_iterator i
, s
= bsi_start (bb
);
4011 for (i
= s
; !bsi_end_p (i
); first
= false, bsi_next (&i
))
4013 stmt
= bsi_stmt (i
);
4014 if (TREE_CODE (stmt
) != LABEL_EXPR
)
4016 label
= LABEL_EXPR_LABEL (stmt
);
4017 if (!DECL_NONLOCAL (label
))
4020 bsi_move_before (&i
, &s
);
4025 label
= create_artificial_label ();
4026 stmt
= build1 (LABEL_EXPR
, void_type_node
, label
);
4027 bsi_insert_before (&s
, stmt
, BSI_NEW_STMT
);
4032 /* Attempt to perform edge redirection by replacing a possibly complex
4033 jump instruction by a goto or by removing the jump completely.
4034 This can apply only if all edges now point to the same block. The
4035 parameters and return values are equivalent to
4036 redirect_edge_and_branch. */
4039 tree_try_redirect_by_replacing_jump (edge e
, basic_block target
)
4041 basic_block src
= e
->src
;
4043 block_stmt_iterator b
;
4046 /* Verify that all targets will be TARGET. */
4047 for (tmp
= src
->succ
; tmp
; tmp
= tmp
->succ_next
)
4048 if (tmp
->dest
!= target
&& tmp
!= e
)
4057 stmt
= bsi_stmt (b
);
4059 if (TREE_CODE (stmt
) == COND_EXPR
4060 || TREE_CODE (stmt
) == SWITCH_EXPR
)
4063 e
= ssa_redirect_edge (e
, target
);
4064 e
->flags
= EDGE_FALLTHRU
;
4072 /* Redirect E to DEST. Return NULL on failure. Otherwise, return the
4073 edge representing the redirected branch. */
4076 tree_redirect_edge_and_branch (edge e
, basic_block dest
)
4078 basic_block bb
= e
->src
;
4079 block_stmt_iterator bsi
;
4083 if (e
->flags
& (EDGE_ABNORMAL_CALL
| EDGE_EH
))
4086 if (e
->src
!= ENTRY_BLOCK_PTR
4087 && (ret
= tree_try_redirect_by_replacing_jump (e
, dest
)))
4090 if (e
->dest
== dest
)
4093 label
= tree_block_label (dest
);
4095 bsi
= bsi_last (bb
);
4096 stmt
= bsi_end_p (bsi
) ? NULL
: bsi_stmt (bsi
);
4098 switch (stmt
? TREE_CODE (stmt
) : ERROR_MARK
)
4101 stmt
= (e
->flags
& EDGE_TRUE_VALUE
4102 ? COND_EXPR_THEN (stmt
)
4103 : COND_EXPR_ELSE (stmt
));
4104 GOTO_DESTINATION (stmt
) = label
;
4108 /* No non-abnormal edges should lead from a non-simple goto, and
4109 simple ones should be represented implicitly. */
4114 tree vec
= SWITCH_LABELS (stmt
);
4115 size_t i
, n
= TREE_VEC_LENGTH (vec
);
4117 for (i
= 0; i
< n
; ++i
)
4119 tree elt
= TREE_VEC_ELT (vec
, i
);
4120 if (label_to_block (CASE_LABEL (elt
)) == e
->dest
)
4121 CASE_LABEL (elt
) = label
;
4128 e
->flags
|= EDGE_FALLTHRU
;
4132 /* Otherwise it must be a fallthru edge, and we don't need to
4133 do anything besides redirecting it. */
4134 if (!(e
->flags
& EDGE_FALLTHRU
))
4139 /* Update/insert PHI nodes as necessary. */
4141 /* Now update the edges in the CFG. */
4142 e
= ssa_redirect_edge (e
, dest
);
4148 /* Simple wrapper, as we can always redirect fallthru edges. */
4151 tree_redirect_edge_and_branch_force (edge e
, basic_block dest
)
4153 e
= tree_redirect_edge_and_branch (e
, dest
);
4161 /* Splits basic block BB after statement STMT (but at least after the
4162 labels). If STMT is NULL, BB is split just after the labels. */
4165 tree_split_block (basic_block bb
, void *stmt
)
4167 block_stmt_iterator bsi
, bsi_tgt
;
4172 new_bb
= create_empty_bb (bb
);
4174 /* Redirect the outgoing edges. */
4175 new_bb
->succ
= bb
->succ
;
4177 for (e
= new_bb
->succ
; e
; e
= e
->succ_next
)
4180 if (stmt
&& TREE_CODE ((tree
) stmt
) == LABEL_EXPR
)
4183 /* Move everything from BSI to the new basic block. */
4184 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
4186 act
= bsi_stmt (bsi
);
4187 if (TREE_CODE (act
) == LABEL_EXPR
)
4200 bsi_tgt
= bsi_start (new_bb
);
4201 while (!bsi_end_p (bsi
))
4203 act
= bsi_stmt (bsi
);
4205 bsi_insert_after (&bsi_tgt
, act
, BSI_NEW_STMT
);
4212 /* Moves basic block BB after block AFTER. */
4215 tree_move_block_after (basic_block bb
, basic_block after
)
4217 if (bb
->prev_bb
== after
)
4221 link_block (bb
, after
);
4227 /* Return true if basic_block can be duplicated. */
4230 tree_can_duplicate_bb_p (basic_block bb ATTRIBUTE_UNUSED
)
4236 /* Create a duplicate of the basic block BB. NOTE: This does not
4237 preserve SSA form. */
4240 tree_duplicate_bb (basic_block bb
)
4243 block_stmt_iterator bsi
, bsi_tgt
;
4245 new_bb
= create_empty_bb (EXIT_BLOCK_PTR
->prev_bb
);
4246 bsi_tgt
= bsi_start (new_bb
);
4247 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
4249 tree stmt
= bsi_stmt (bsi
);
4252 if (TREE_CODE (stmt
) == LABEL_EXPR
)
4255 copy
= unshare_expr (stmt
);
4257 /* Copy also the virtual operands. */
4258 get_stmt_ann (copy
);
4259 copy_virtual_operands (copy
, stmt
);
4261 bsi_insert_after (&bsi_tgt
, copy
, BSI_NEW_STMT
);
4268 /* Dump FUNCTION_DECL FN to file FILE using FLAGS (see TDF_* in tree.h) */
4271 dump_function_to_file (tree fn
, FILE *file
, int flags
)
4273 tree arg
, vars
, var
;
4274 bool ignore_topmost_bind
= false, any_var
= false;
4278 fprintf (file
, "%s (", lang_hooks
.decl_printable_name (fn
, 2));
4280 arg
= DECL_ARGUMENTS (fn
);
4283 print_generic_expr (file
, arg
, dump_flags
);
4284 if (TREE_CHAIN (arg
))
4285 fprintf (file
, ", ");
4286 arg
= TREE_CHAIN (arg
);
4288 fprintf (file
, ")\n");
4290 if (flags
& TDF_RAW
)
4292 dump_node (fn
, TDF_SLIM
| flags
, file
);
4296 /* When GIMPLE is lowered, the variables are no longer available in
4297 BIND_EXPRs, so display them separately. */
4298 if (cfun
&& cfun
->unexpanded_var_list
)
4300 ignore_topmost_bind
= true;
4302 fprintf (file
, "{\n");
4303 for (vars
= cfun
->unexpanded_var_list
; vars
; vars
= TREE_CHAIN (vars
))
4305 var
= TREE_VALUE (vars
);
4307 print_generic_decl (file
, var
, flags
);
4308 fprintf (file
, "\n");
4314 if (basic_block_info
)
4316 /* Make a CFG based dump. */
4317 if (!ignore_topmost_bind
)
4318 fprintf (file
, "{\n");
4320 if (any_var
&& n_basic_blocks
)
4321 fprintf (file
, "\n");
4324 dump_generic_bb (file
, bb
, 2, flags
);
4326 fprintf (file
, "}\n");
4332 /* Make a tree based dump. */
4333 chain
= DECL_SAVED_TREE (fn
);
4335 if (TREE_CODE (chain
) == BIND_EXPR
)
4337 if (ignore_topmost_bind
)
4339 chain
= BIND_EXPR_BODY (chain
);
4347 if (!ignore_topmost_bind
)
4348 fprintf (file
, "{\n");
4353 fprintf (file
, "\n");
4355 print_generic_stmt_indented (file
, chain
, flags
, indent
);
4356 if (ignore_topmost_bind
)
4357 fprintf (file
, "}\n");
4360 fprintf (file
, "\n\n");
4364 /* Pretty print of the loops intermediate representation. */
4365 static void print_loop (FILE *, struct loop
*, int);
4366 static void print_pred_bbs (FILE *, edge
);
4367 static void print_succ_bbs (FILE *, edge
);
4370 /* Print the predecessors indexes of edge E on FILE. */
4373 print_pred_bbs (FILE *file
, edge e
)
4378 else if (e
->pred_next
== NULL
)
4379 fprintf (file
, "bb_%d", e
->src
->index
);
4383 fprintf (file
, "bb_%d, ", e
->src
->index
);
4384 print_pred_bbs (file
, e
->pred_next
);
4389 /* Print the successors indexes of edge E on FILE. */
4392 print_succ_bbs (FILE *file
, edge e
)
4396 else if (e
->succ_next
== NULL
)
4397 fprintf (file
, "bb_%d", e
->dest
->index
);
4400 fprintf (file
, "bb_%d, ", e
->dest
->index
);
4401 print_succ_bbs (file
, e
->succ_next
);
4406 /* Pretty print LOOP on FILE, indented INDENT spaces. */
4409 print_loop (FILE *file
, struct loop
*loop
, int indent
)
4417 s_indent
= (char *) alloca ((size_t) indent
+ 1);
4418 memset ((void *) s_indent
, ' ', (size_t) indent
);
4419 s_indent
[indent
] = '\0';
4421 /* Print the loop's header. */
4422 fprintf (file
, "%sloop_%d\n", s_indent
, loop
->num
);
4424 /* Print the loop's body. */
4425 fprintf (file
, "%s{\n", s_indent
);
4427 if (bb
->loop_father
== loop
)
4429 /* Print the basic_block's header. */
4430 fprintf (file
, "%s bb_%d (preds = {", s_indent
, bb
->index
);
4431 print_pred_bbs (file
, bb
->pred
);
4432 fprintf (file
, "}, succs = {");
4433 print_succ_bbs (file
, bb
->succ
);
4434 fprintf (file
, "})\n");
4436 /* Print the basic_block's body. */
4437 fprintf (file
, "%s {\n", s_indent
);
4438 tree_dump_bb (bb
, file
, indent
+ 4);
4439 fprintf (file
, "%s }\n", s_indent
);
4442 print_loop (file
, loop
->inner
, indent
+ 2);
4443 fprintf (file
, "%s}\n", s_indent
);
4444 print_loop (file
, loop
->next
, indent
);
4448 /* Follow a CFG edge from the entry point of the program, and on entry
4449 of a loop, pretty print the loop structure on FILE. */
4452 print_loop_ir (FILE *file
)
4456 bb
= BASIC_BLOCK (0);
4457 if (bb
&& bb
->loop_father
)
4458 print_loop (file
, bb
->loop_father
, 0);
4462 /* Debugging loops structure at tree level. */
4465 debug_loop_ir (void)
4467 print_loop_ir (stderr
);
4471 /* Return true if BB ends with a call, possibly followed by some
4472 instructions that must stay with the call. Return false,
4476 tree_block_ends_with_call_p (basic_block bb
)
4478 block_stmt_iterator bsi
= bsi_last (bb
);
4479 return get_call_expr_in (bsi_stmt (bsi
)) != NULL
;
4483 /* Return true if BB ends with a conditional branch. Return false,
4487 tree_block_ends_with_condjump_p (basic_block bb
)
4489 tree stmt
= tsi_stmt (bsi_last (bb
).tsi
);
4490 return (TREE_CODE (stmt
) == COND_EXPR
);
4494 /* Return true if we need to add fake edge to exit at statement T.
4495 Helper function for tree_flow_call_edges_add. */
4498 need_fake_edge_p (tree t
)
4502 /* NORETURN and LONGJMP calls already have an edge to exit.
4503 CONST, PURE and ALWAYS_RETURN calls do not need one.
4504 We don't currently check for CONST and PURE here, although
4505 it would be a good idea, because those attributes are
4506 figured out from the RTL in mark_constant_function, and
4507 the counter incrementation code from -fprofile-arcs
4508 leads to different results from -fbranch-probabilities. */
4509 call
= get_call_expr_in (t
);
4511 && !(call_expr_flags (call
) &
4512 (ECF_NORETURN
| ECF_LONGJMP
| ECF_ALWAYS_RETURN
)))
4515 if (TREE_CODE (t
) == ASM_EXPR
4516 && (ASM_VOLATILE_P (t
) || ASM_INPUT_P (t
)))
4523 /* Add fake edges to the function exit for any non constant and non
4524 noreturn calls, volatile inline assembly in the bitmap of blocks
4525 specified by BLOCKS or to the whole CFG if BLOCKS is zero. Return
4526 the number of blocks that were split.
4528 The goal is to expose cases in which entering a basic block does
4529 not imply that all subsequent instructions must be executed. */
4532 tree_flow_call_edges_add (sbitmap blocks
)
4535 int blocks_split
= 0;
4536 int last_bb
= last_basic_block
;
4537 bool check_last_block
= false;
4539 if (n_basic_blocks
== 0)
4543 check_last_block
= true;
4545 check_last_block
= TEST_BIT (blocks
, EXIT_BLOCK_PTR
->prev_bb
->index
);
4547 /* In the last basic block, before epilogue generation, there will be
4548 a fallthru edge to EXIT. Special care is required if the last insn
4549 of the last basic block is a call because make_edge folds duplicate
4550 edges, which would result in the fallthru edge also being marked
4551 fake, which would result in the fallthru edge being removed by
4552 remove_fake_edges, which would result in an invalid CFG.
4554 Moreover, we can't elide the outgoing fake edge, since the block
4555 profiler needs to take this into account in order to solve the minimal
4556 spanning tree in the case that the call doesn't return.
4558 Handle this by adding a dummy instruction in a new last basic block. */
4559 if (check_last_block
)
4561 basic_block bb
= EXIT_BLOCK_PTR
->prev_bb
;
4562 block_stmt_iterator bsi
= bsi_last (bb
);
4564 if (!bsi_end_p (bsi
))
4567 if (need_fake_edge_p (t
))
4571 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
4572 if (e
->dest
== EXIT_BLOCK_PTR
)
4574 bsi_insert_on_edge (e
, build_empty_stmt ());
4575 bsi_commit_edge_inserts ((int *)NULL
);
4581 /* Now add fake edges to the function exit for any non constant
4582 calls since there is no way that we can determine if they will
4584 for (i
= 0; i
< last_bb
; i
++)
4586 basic_block bb
= BASIC_BLOCK (i
);
4587 block_stmt_iterator bsi
;
4588 tree stmt
, last_stmt
;
4593 if (blocks
&& !TEST_BIT (blocks
, i
))
4596 bsi
= bsi_last (bb
);
4597 if (!bsi_end_p (bsi
))
4599 last_stmt
= bsi_stmt (bsi
);
4602 stmt
= bsi_stmt (bsi
);
4603 if (need_fake_edge_p (stmt
))
4606 /* The handling above of the final block before the
4607 epilogue should be enough to verify that there is
4608 no edge to the exit block in CFG already.
4609 Calling make_edge in such case would cause us to
4610 mark that edge as fake and remove it later. */
4611 #ifdef ENABLE_CHECKING
4612 if (stmt
== last_stmt
)
4613 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
4614 if (e
->dest
== EXIT_BLOCK_PTR
)
4618 /* Note that the following may create a new basic block
4619 and renumber the existing basic blocks. */
4620 if (stmt
!= last_stmt
)
4622 e
= split_block (bb
, stmt
);
4626 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
4630 while (!bsi_end_p (bsi
));
4635 verify_flow_info ();
4637 return blocks_split
;
4641 tree_purge_dead_eh_edges (basic_block bb
)
4643 bool changed
= false;
4645 tree stmt
= last_stmt (bb
);
4647 if (stmt
&& tree_can_throw_internal (stmt
))
4650 for (e
= bb
->succ
; e
; e
= next
)
4652 next
= e
->succ_next
;
4653 if (e
->flags
& EDGE_EH
)
4655 ssa_remove_edge (e
);
4664 tree_purge_all_dead_eh_edges (bitmap blocks
)
4666 bool changed
= false;
4669 EXECUTE_IF_SET_IN_BITMAP (blocks
, 0, i
,
4670 { changed
|= tree_purge_dead_eh_edges (BASIC_BLOCK (i
)); });
4675 struct cfg_hooks tree_cfg_hooks
= {
4677 tree_verify_flow_info
,
4678 tree_dump_bb
, /* dump_bb */
4679 create_bb
, /* create_basic_block */
4680 tree_redirect_edge_and_branch
,/* redirect_edge_and_branch */
4681 tree_redirect_edge_and_branch_force
,/* redirect_edge_and_branch_force */
4682 remove_bb
, /* delete_basic_block */
4683 tree_split_block
, /* split_block */
4684 tree_move_block_after
, /* move_block_after */
4685 tree_can_merge_blocks_p
, /* can_merge_blocks_p */
4686 tree_merge_blocks
, /* merge_blocks */
4687 tree_predict_edge
, /* predict_edge */
4688 tree_predicted_by_p
, /* predicted_by_p */
4689 tree_can_duplicate_bb_p
, /* can_duplicate_block_p */
4690 tree_duplicate_bb
, /* duplicate_block */
4691 tree_split_edge
, /* split_edge */
4692 tree_make_forwarder_block
, /* make_forward_block */
4693 NULL
, /* tidy_fallthru_edge */
4694 tree_block_ends_with_call_p
, /* block_ends_with_call_p */
4695 tree_block_ends_with_condjump_p
, /* block_ends_with_condjump_p */
4696 tree_flow_call_edges_add
/* flow_call_edges_add */
4700 /* Split all critical edges. */
4703 split_critical_edges (void)
4710 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
4711 if (EDGE_CRITICAL_P (e
) && !(e
->flags
& EDGE_ABNORMAL
))
4718 struct tree_opt_pass pass_split_crit_edges
=
4720 "crited", /* name */
4722 split_critical_edges
, /* execute */
4725 0, /* static_pass_number */
4726 TV_TREE_SPLIT_EDGES
, /* tv_id */
4727 PROP_cfg
, /* properties required */
4728 PROP_no_crit_edges
, /* properties_provided */
4729 0, /* properties_destroyed */
4730 0, /* todo_flags_start */
4731 TODO_dump_func
, /* todo_flags_finish */
4734 /* Emit return warnings. */
4737 execute_warn_function_return (void)
4739 #ifdef USE_MAPPED_LOCATION
4740 source_location location
;
4747 if (warn_missing_noreturn
4748 && !TREE_THIS_VOLATILE (cfun
->decl
)
4749 && EXIT_BLOCK_PTR
->pred
== NULL
4750 && !lang_hooks
.function
.missing_noreturn_ok_p (cfun
->decl
))
4751 warning ("%Jfunction might be possible candidate for attribute `noreturn'",
4754 /* If we have a path to EXIT, then we do return. */
4755 if (TREE_THIS_VOLATILE (cfun
->decl
)
4756 && EXIT_BLOCK_PTR
->pred
!= NULL
)
4758 #ifdef USE_MAPPED_LOCATION
4759 location
= UNKNOWN_LOCATION
;
4763 for (e
= EXIT_BLOCK_PTR
->pred
; e
; e
= e
->pred_next
)
4765 last
= last_stmt (e
->src
);
4766 if (TREE_CODE (last
) == RETURN_EXPR
4767 #ifdef USE_MAPPED_LOCATION
4768 && (location
= EXPR_LOCATION (last
)) != UNKNOWN_LOCATION
)
4770 && (locus
= EXPR_LOCUS (last
)) != NULL
)
4774 #ifdef USE_MAPPED_LOCATION
4775 if (location
== UNKNOWN_LOCATION
)
4776 location
= cfun
->function_end_locus
;
4777 warning ("%H`noreturn' function does return", &location
);
4780 locus
= &cfun
->function_end_locus
;
4781 warning ("%H`noreturn' function does return", locus
);
4785 /* If we see "return;" in some basic block, then we do reach the end
4786 without returning a value. */
4787 else if (warn_return_type
4788 && EXIT_BLOCK_PTR
->pred
!= NULL
4789 && !VOID_TYPE_P (TREE_TYPE (TREE_TYPE (cfun
->decl
))))
4791 for (e
= EXIT_BLOCK_PTR
->pred
; e
; e
= e
->pred_next
)
4793 tree last
= last_stmt (e
->src
);
4794 if (TREE_CODE (last
) == RETURN_EXPR
4795 && TREE_OPERAND (last
, 0) == NULL
)
4797 #ifdef USE_MAPPED_LOCATION
4798 location
= EXPR_LOCATION (last
);
4799 if (location
== UNKNOWN_LOCATION
)
4800 location
= cfun
->function_end_locus
;
4801 warning ("%Hcontrol reaches end of non-void function", &location
);
4803 locus
= EXPR_LOCUS (last
);
4805 locus
= &cfun
->function_end_locus
;
4806 warning ("%Hcontrol reaches end of non-void function", locus
);
4815 /* Given a basic block B which ends with a conditional and has
4816 precisely two successors, determine which of the edges is taken if
4817 the conditional is true and which is taken if the conditional is
4818 false. Set TRUE_EDGE and FALSE_EDGE appropriately. */
4821 extract_true_false_edges_from_block (basic_block b
,
4827 if (e
->flags
& EDGE_TRUE_VALUE
)
4830 *false_edge
= e
->succ_next
;
4835 *true_edge
= e
->succ_next
;
4839 struct tree_opt_pass pass_warn_function_return
=
4843 execute_warn_function_return
, /* execute */
4846 0, /* static_pass_number */
4848 PROP_cfg
, /* properties_required */
4849 0, /* properties_provided */
4850 0, /* properties_destroyed */
4851 0, /* todo_flags_start */
4852 0 /* todo_flags_finish */
4855 #include "gt-tree-cfg.h"