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 predicate VAL, return the edge that
1995 will be taken out of the block. If VAL does not match a unique
1996 edge, 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 a predicate of the form N RELOP N, where N is an
2011 SSA_NAME, we can always determine its truth value (except when
2012 doing floating point comparisons that may involve NaNs). */
2014 && TREE_CODE_CLASS (TREE_CODE (val
)) == '<'
2015 && TREE_OPERAND (val
, 0) == TREE_OPERAND (val
, 1)
2016 && TREE_CODE (TREE_OPERAND (val
, 0)) == SSA_NAME
2017 && (TREE_CODE (TREE_TYPE (TREE_OPERAND (val
, 0))) != REAL_TYPE
2018 || !HONOR_NANS (TYPE_MODE (TREE_TYPE (TREE_OPERAND (val
, 0))))))
2020 enum tree_code code
= TREE_CODE (val
);
2022 if (code
== EQ_EXPR
|| code
== LE_EXPR
|| code
== GE_EXPR
)
2023 val
= boolean_true_node
;
2024 else if (code
== LT_EXPR
|| code
== GT_EXPR
|| code
== NE_EXPR
)
2025 val
= boolean_false_node
;
2028 /* If VAL is not a constant, we can't determine which edge might
2030 if (val
== NULL
|| !really_constant_p (val
))
2033 if (TREE_CODE (stmt
) == COND_EXPR
)
2034 return find_taken_edge_cond_expr (bb
, val
);
2036 if (TREE_CODE (stmt
) == SWITCH_EXPR
)
2037 return find_taken_edge_switch_expr (bb
, val
);
2043 /* Given a constant value VAL and the entry block BB to a COND_EXPR
2044 statement, determine which of the two edges will be taken out of the
2045 block. Return NULL if either edge may be taken. */
2048 find_taken_edge_cond_expr (basic_block bb
, tree val
)
2050 edge true_edge
, false_edge
;
2052 extract_true_false_edges_from_block (bb
, &true_edge
, &false_edge
);
2054 /* If both edges of the branch lead to the same basic block, it doesn't
2055 matter which edge is taken. */
2056 if (true_edge
->dest
== false_edge
->dest
)
2059 /* Otherwise, try to determine which branch of the if() will be taken.
2060 If VAL is a constant but it can't be reduced to a 0 or a 1, then
2061 we don't really know which edge will be taken at runtime. This
2062 may happen when comparing addresses (e.g., if (&var1 == 4)). */
2063 if (integer_nonzerop (val
))
2065 else if (integer_zerop (val
))
2072 /* Given a constant value VAL and the entry block BB to a SWITCH_EXPR
2073 statement, determine which edge will be taken out of the block. Return
2074 NULL if any edge may be taken. */
2077 find_taken_edge_switch_expr (basic_block bb
, tree val
)
2079 tree switch_expr
, taken_case
;
2080 basic_block dest_bb
;
2083 if (TREE_CODE (val
) != INTEGER_CST
)
2086 switch_expr
= last_stmt (bb
);
2087 taken_case
= find_case_label_for_value (switch_expr
, val
);
2088 dest_bb
= label_to_block (CASE_LABEL (taken_case
));
2090 e
= find_edge (bb
, dest_bb
);
2097 /* Return the CASE_LABEL_EXPR that SWITCH_EXPR will take for VAL.
2098 We can make optimal use here of the fact that the case labels are
2099 sorted: We can do a binary search for a case matching VAL. */
2102 find_case_label_for_value (tree switch_expr
, tree val
)
2104 tree vec
= SWITCH_LABELS (switch_expr
);
2105 size_t low
, high
, n
= TREE_VEC_LENGTH (vec
);
2106 tree default_case
= TREE_VEC_ELT (vec
, n
- 1);
2108 for (low
= -1, high
= n
- 1; high
- low
> 1; )
2110 size_t i
= (high
+ low
) / 2;
2111 tree t
= TREE_VEC_ELT (vec
, i
);
2114 /* Cache the result of comparing CASE_LOW and val. */
2115 cmp
= tree_int_cst_compare (CASE_LOW (t
), val
);
2122 if (CASE_HIGH (t
) == NULL
)
2124 /* A singe-valued case label. */
2130 /* A case range. We can only handle integer ranges. */
2131 if (cmp
<= 0 && tree_int_cst_compare (CASE_HIGH (t
), val
) >= 0)
2136 return default_case
;
2140 /* If all the PHI nodes in DEST have alternatives for E1 and E2 and
2141 those alternatives are equal in each of the PHI nodes, then return
2142 true, else return false. */
2145 phi_alternatives_equal (basic_block dest
, edge e1
, edge e2
)
2147 tree phi
, val1
, val2
;
2150 for (phi
= phi_nodes (dest
); phi
; phi
= PHI_CHAIN (phi
))
2152 n1
= phi_arg_from_edge (phi
, e1
);
2153 n2
= phi_arg_from_edge (phi
, e2
);
2155 #ifdef ENABLE_CHECKING
2156 if (n1
< 0 || n2
< 0)
2160 val1
= PHI_ARG_DEF (phi
, n1
);
2161 val2
= PHI_ARG_DEF (phi
, n2
);
2163 if (!operand_equal_p (val1
, val2
, 0))
2171 /* Computing the Dominance Frontier:
2173 As described in Morgan, section 3.5, this may be done simply by
2174 walking the dominator tree bottom-up, computing the frontier for
2175 the children before the parent. When considering a block B,
2176 there are two cases:
2178 (1) A flow graph edge leaving B that does not lead to a child
2179 of B in the dominator tree must be a block that is either equal
2180 to B or not dominated by B. Such blocks belong in the frontier
2183 (2) Consider a block X in the frontier of one of the children C
2184 of B. If X is not equal to B and is not dominated by B, it
2185 is in the frontier of B. */
2188 compute_dominance_frontiers_1 (bitmap
*frontiers
, basic_block bb
, sbitmap done
)
2193 SET_BIT (done
, bb
->index
);
2195 /* Do the frontier of the children first. Not all children in the
2196 dominator tree (blocks dominated by this one) are children in the
2197 CFG, so check all blocks. */
2198 for (c
= first_dom_son (CDI_DOMINATORS
, bb
);
2200 c
= next_dom_son (CDI_DOMINATORS
, c
))
2202 if (! TEST_BIT (done
, c
->index
))
2203 compute_dominance_frontiers_1 (frontiers
, c
, done
);
2206 /* Find blocks conforming to rule (1) above. */
2207 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
2209 if (e
->dest
== EXIT_BLOCK_PTR
)
2211 if (get_immediate_dominator (CDI_DOMINATORS
, e
->dest
) != bb
)
2212 bitmap_set_bit (frontiers
[bb
->index
], e
->dest
->index
);
2215 /* Find blocks conforming to rule (2). */
2216 for (c
= first_dom_son (CDI_DOMINATORS
, bb
);
2218 c
= next_dom_son (CDI_DOMINATORS
, c
))
2222 EXECUTE_IF_SET_IN_BITMAP (frontiers
[c
->index
], 0, x
,
2224 if (get_immediate_dominator (CDI_DOMINATORS
, BASIC_BLOCK (x
)) != bb
)
2225 bitmap_set_bit (frontiers
[bb
->index
], x
);
2232 compute_dominance_frontiers (bitmap
*frontiers
)
2234 sbitmap done
= sbitmap_alloc (last_basic_block
);
2236 timevar_push (TV_DOM_FRONTIERS
);
2238 sbitmap_zero (done
);
2240 compute_dominance_frontiers_1 (frontiers
, ENTRY_BLOCK_PTR
->succ
->dest
, done
);
2242 sbitmap_free (done
);
2244 timevar_pop (TV_DOM_FRONTIERS
);
2249 /*---------------------------------------------------------------------------
2251 ---------------------------------------------------------------------------*/
2253 /* Dump tree-specific information of block BB to file OUTF. */
2256 tree_dump_bb (basic_block bb
, FILE *outf
, int indent
)
2258 dump_generic_bb (outf
, bb
, indent
, TDF_VOPS
);
2262 /* Dump a basic block on stderr. */
2265 debug_tree_bb (basic_block bb
)
2267 dump_bb (bb
, stderr
, 0);
2271 /* Dump basic block with index N on stderr. */
2274 debug_tree_bb_n (int n
)
2276 debug_tree_bb (BASIC_BLOCK (n
));
2277 return BASIC_BLOCK (n
);
2281 /* Dump the CFG on stderr.
2283 FLAGS are the same used by the tree dumping functions
2284 (see TDF_* in tree.h). */
2287 debug_tree_cfg (int flags
)
2289 dump_tree_cfg (stderr
, flags
);
2293 /* Dump the program showing basic block boundaries on the given FILE.
2295 FLAGS are the same used by the tree dumping functions (see TDF_* in
2299 dump_tree_cfg (FILE *file
, int flags
)
2301 if (flags
& TDF_DETAILS
)
2303 const char *funcname
2304 = lang_hooks
.decl_printable_name (current_function_decl
, 2);
2307 fprintf (file
, ";; Function %s\n\n", funcname
);
2308 fprintf (file
, ";; \n%d basic blocks, %d edges, last basic block %d.\n\n",
2309 n_basic_blocks
, n_edges
, last_basic_block
);
2311 brief_dump_cfg (file
);
2312 fprintf (file
, "\n");
2315 if (flags
& TDF_STATS
)
2316 dump_cfg_stats (file
);
2318 dump_function_to_file (current_function_decl
, file
, flags
| TDF_BLOCKS
);
2322 /* Dump CFG statistics on FILE. */
2325 dump_cfg_stats (FILE *file
)
2327 static long max_num_merged_labels
= 0;
2328 unsigned long size
, total
= 0;
2331 const char * const fmt_str
= "%-30s%-13s%12s\n";
2332 const char * const fmt_str_1
= "%-30s%13d%11lu%c\n";
2333 const char * const fmt_str_3
= "%-43s%11lu%c\n";
2334 const char *funcname
2335 = lang_hooks
.decl_printable_name (current_function_decl
, 2);
2338 fprintf (file
, "\nCFG Statistics for %s\n\n", funcname
);
2340 fprintf (file
, "---------------------------------------------------------\n");
2341 fprintf (file
, fmt_str
, "", " Number of ", "Memory");
2342 fprintf (file
, fmt_str
, "", " instances ", "used ");
2343 fprintf (file
, "---------------------------------------------------------\n");
2345 size
= n_basic_blocks
* sizeof (struct basic_block_def
);
2347 fprintf (file
, fmt_str_1
, "Basic blocks", n_basic_blocks
,
2348 SCALE (size
), LABEL (size
));
2354 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
2357 size
= n_edges
* sizeof (struct edge_def
);
2359 fprintf (file
, fmt_str_1
, "Edges", n_edges
, SCALE (size
), LABEL (size
));
2361 size
= n_basic_blocks
* sizeof (struct bb_ann_d
);
2363 fprintf (file
, fmt_str_1
, "Basic block annotations", n_basic_blocks
,
2364 SCALE (size
), LABEL (size
));
2366 fprintf (file
, "---------------------------------------------------------\n");
2367 fprintf (file
, fmt_str_3
, "Total memory used by CFG data", SCALE (total
),
2369 fprintf (file
, "---------------------------------------------------------\n");
2370 fprintf (file
, "\n");
2372 if (cfg_stats
.num_merged_labels
> max_num_merged_labels
)
2373 max_num_merged_labels
= cfg_stats
.num_merged_labels
;
2375 fprintf (file
, "Coalesced label blocks: %ld (Max so far: %ld)\n",
2376 cfg_stats
.num_merged_labels
, max_num_merged_labels
);
2378 fprintf (file
, "\n");
2382 /* Dump CFG statistics on stderr. Keep extern so that it's always
2383 linked in the final executable. */
2386 debug_cfg_stats (void)
2388 dump_cfg_stats (stderr
);
2392 /* Dump the flowgraph to a .vcg FILE. */
2395 tree_cfg2vcg (FILE *file
)
2399 const char *funcname
2400 = lang_hooks
.decl_printable_name (current_function_decl
, 2);
2402 /* Write the file header. */
2403 fprintf (file
, "graph: { title: \"%s\"\n", funcname
);
2404 fprintf (file
, "node: { title: \"ENTRY\" label: \"ENTRY\" }\n");
2405 fprintf (file
, "node: { title: \"EXIT\" label: \"EXIT\" }\n");
2407 /* Write blocks and edges. */
2408 for (e
= ENTRY_BLOCK_PTR
->succ
; e
; e
= e
->succ_next
)
2410 fprintf (file
, "edge: { sourcename: \"ENTRY\" targetname: \"%d\"",
2413 if (e
->flags
& EDGE_FAKE
)
2414 fprintf (file
, " linestyle: dotted priority: 10");
2416 fprintf (file
, " linestyle: solid priority: 100");
2418 fprintf (file
, " }\n");
2424 enum tree_code head_code
, end_code
;
2425 const char *head_name
, *end_name
;
2428 tree first
= first_stmt (bb
);
2429 tree last
= last_stmt (bb
);
2433 head_code
= TREE_CODE (first
);
2434 head_name
= tree_code_name
[head_code
];
2435 head_line
= get_lineno (first
);
2438 head_name
= "no-statement";
2442 end_code
= TREE_CODE (last
);
2443 end_name
= tree_code_name
[end_code
];
2444 end_line
= get_lineno (last
);
2447 end_name
= "no-statement";
2449 fprintf (file
, "node: { title: \"%d\" label: \"#%d\\n%s (%d)\\n%s (%d)\"}\n",
2450 bb
->index
, bb
->index
, head_name
, head_line
, end_name
,
2453 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
2455 if (e
->dest
== EXIT_BLOCK_PTR
)
2456 fprintf (file
, "edge: { sourcename: \"%d\" targetname: \"EXIT\"", bb
->index
);
2458 fprintf (file
, "edge: { sourcename: \"%d\" targetname: \"%d\"", bb
->index
, e
->dest
->index
);
2460 if (e
->flags
& EDGE_FAKE
)
2461 fprintf (file
, " priority: 10 linestyle: dotted");
2463 fprintf (file
, " priority: 100 linestyle: solid");
2465 fprintf (file
, " }\n");
2468 if (bb
->next_bb
!= EXIT_BLOCK_PTR
)
2472 fputs ("}\n\n", file
);
2477 /*---------------------------------------------------------------------------
2478 Miscellaneous helpers
2479 ---------------------------------------------------------------------------*/
2481 /* Return true if T represents a stmt that always transfers control. */
2484 is_ctrl_stmt (tree t
)
2486 return (TREE_CODE (t
) == COND_EXPR
2487 || TREE_CODE (t
) == SWITCH_EXPR
2488 || TREE_CODE (t
) == GOTO_EXPR
2489 || TREE_CODE (t
) == RETURN_EXPR
2490 || TREE_CODE (t
) == RESX_EXPR
);
2494 /* Return true if T is a statement that may alter the flow of control
2495 (e.g., a call to a non-returning function). */
2498 is_ctrl_altering_stmt (tree t
)
2502 #if defined ENABLE_CHECKING
2507 call
= get_call_expr_in (t
);
2510 /* A non-pure/const CALL_EXPR alters flow control if the current
2511 function has nonlocal labels. */
2512 if (TREE_SIDE_EFFECTS (call
) && current_function_has_nonlocal_label
)
2515 /* A CALL_EXPR also alters control flow if it does not return. */
2516 if (call_expr_flags (call
) & (ECF_NORETURN
| ECF_LONGJMP
))
2520 /* If a statement can throw, it alters control flow. */
2521 return tree_can_throw_internal (t
);
2525 /* Return true if T is a computed goto. */
2528 computed_goto_p (tree t
)
2530 return (TREE_CODE (t
) == GOTO_EXPR
2531 && TREE_CODE (GOTO_DESTINATION (t
)) != LABEL_DECL
);
2535 /* Checks whether EXPR is a simple local goto. */
2538 simple_goto_p (tree expr
)
2540 return (TREE_CODE (expr
) == GOTO_EXPR
2541 && TREE_CODE (GOTO_DESTINATION (expr
)) == LABEL_DECL
2542 && (decl_function_context (GOTO_DESTINATION (expr
))
2543 == current_function_decl
));
2547 /* Return true if T should start a new basic block. PREV_T is the
2548 statement preceding T. It is used when T is a label or a case label.
2549 Labels should only start a new basic block if their previous statement
2550 wasn't a label. Otherwise, sequence of labels would generate
2551 unnecessary basic blocks that only contain a single label. */
2554 stmt_starts_bb_p (tree t
, tree prev_t
)
2556 enum tree_code code
;
2561 /* LABEL_EXPRs start a new basic block only if the preceding
2562 statement wasn't a label of the same type. This prevents the
2563 creation of consecutive blocks that have nothing but a single
2565 code
= TREE_CODE (t
);
2566 if (code
== LABEL_EXPR
)
2568 /* Nonlocal and computed GOTO targets always start a new block. */
2569 if (code
== LABEL_EXPR
2570 && (DECL_NONLOCAL (LABEL_EXPR_LABEL (t
))
2571 || FORCED_LABEL (LABEL_EXPR_LABEL (t
))))
2574 if (prev_t
&& TREE_CODE (prev_t
) == code
)
2576 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (prev_t
)))
2579 cfg_stats
.num_merged_labels
++;
2590 /* Return true if T should end a basic block. */
2593 stmt_ends_bb_p (tree t
)
2595 return is_ctrl_stmt (t
) || is_ctrl_altering_stmt (t
);
2599 /* Add gotos that used to be represented implicitly in the CFG. */
2602 disband_implicit_edges (void)
2605 block_stmt_iterator last
;
2611 last
= bsi_last (bb
);
2612 stmt
= last_stmt (bb
);
2614 if (stmt
&& TREE_CODE (stmt
) == COND_EXPR
)
2616 /* Remove superfluous gotos from COND_EXPR branches. Moved
2617 from cfg_remove_useless_stmts here since it violates the
2618 invariants for tree--cfg correspondence and thus fits better
2619 here where we do it anyway. */
2620 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
2622 if (e
->dest
!= bb
->next_bb
)
2625 if (e
->flags
& EDGE_TRUE_VALUE
)
2626 COND_EXPR_THEN (stmt
) = build_empty_stmt ();
2627 else if (e
->flags
& EDGE_FALSE_VALUE
)
2628 COND_EXPR_ELSE (stmt
) = build_empty_stmt ();
2631 e
->flags
|= EDGE_FALLTHRU
;
2637 if (stmt
&& TREE_CODE (stmt
) == RETURN_EXPR
)
2639 /* Remove the RETURN_EXPR if we may fall though to the exit
2642 || bb
->succ
->succ_next
2643 || bb
->succ
->dest
!= EXIT_BLOCK_PTR
)
2646 if (bb
->next_bb
== EXIT_BLOCK_PTR
2647 && !TREE_OPERAND (stmt
, 0))
2650 bb
->succ
->flags
|= EDGE_FALLTHRU
;
2655 /* There can be no fallthru edge if the last statement is a control
2657 if (stmt
&& is_ctrl_stmt (stmt
))
2660 /* Find a fallthru edge and emit the goto if necessary. */
2661 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
2662 if (e
->flags
& EDGE_FALLTHRU
)
2665 if (!e
|| e
->dest
== bb
->next_bb
)
2668 if (e
->dest
== EXIT_BLOCK_PTR
)
2671 label
= tree_block_label (e
->dest
);
2673 stmt
= build1 (GOTO_EXPR
, void_type_node
, label
);
2674 #ifdef USE_MAPPED_LOCATION
2675 SET_EXPR_LOCATION (stmt
, e
->goto_locus
);
2677 SET_EXPR_LOCUS (stmt
, e
->goto_locus
);
2679 bsi_insert_after (&last
, stmt
, BSI_NEW_STMT
);
2680 e
->flags
&= ~EDGE_FALLTHRU
;
2684 /* Remove block annotations and other datastructures. */
2687 delete_tree_cfg_annotations (void)
2690 if (n_basic_blocks
> 0)
2691 free_blocks_annotations ();
2693 label_to_block_map
= NULL
;
2700 /* Return the first statement in basic block BB. */
2703 first_stmt (basic_block bb
)
2705 block_stmt_iterator i
= bsi_start (bb
);
2706 return !bsi_end_p (i
) ? bsi_stmt (i
) : NULL_TREE
;
2710 /* Return the last statement in basic block BB. */
2713 last_stmt (basic_block bb
)
2715 block_stmt_iterator b
= bsi_last (bb
);
2716 return !bsi_end_p (b
) ? bsi_stmt (b
) : NULL_TREE
;
2720 /* Return a pointer to the last statement in block BB. */
2723 last_stmt_ptr (basic_block bb
)
2725 block_stmt_iterator last
= bsi_last (bb
);
2726 return !bsi_end_p (last
) ? bsi_stmt_ptr (last
) : NULL
;
2730 /* Return the last statement of an otherwise empty block. Return NULL
2731 if the block is totally empty, or if it contains more than one
2735 last_and_only_stmt (basic_block bb
)
2737 block_stmt_iterator i
= bsi_last (bb
);
2743 last
= bsi_stmt (i
);
2748 /* Empty statements should no longer appear in the instruction stream.
2749 Everything that might have appeared before should be deleted by
2750 remove_useless_stmts, and the optimizers should just bsi_remove
2751 instead of smashing with build_empty_stmt.
2753 Thus the only thing that should appear here in a block containing
2754 one executable statement is a label. */
2755 prev
= bsi_stmt (i
);
2756 if (TREE_CODE (prev
) == LABEL_EXPR
)
2763 /* Mark BB as the basic block holding statement T. */
2766 set_bb_for_stmt (tree t
, basic_block bb
)
2768 if (TREE_CODE (t
) == STATEMENT_LIST
)
2770 tree_stmt_iterator i
;
2771 for (i
= tsi_start (t
); !tsi_end_p (i
); tsi_next (&i
))
2772 set_bb_for_stmt (tsi_stmt (i
), bb
);
2776 stmt_ann_t ann
= get_stmt_ann (t
);
2779 /* If the statement is a label, add the label to block-to-labels map
2780 so that we can speed up edge creation for GOTO_EXPRs. */
2781 if (TREE_CODE (t
) == LABEL_EXPR
)
2785 t
= LABEL_EXPR_LABEL (t
);
2786 uid
= LABEL_DECL_UID (t
);
2789 LABEL_DECL_UID (t
) = uid
= cfun
->last_label_uid
++;
2790 if (VARRAY_SIZE (label_to_block_map
) <= (unsigned) uid
)
2791 VARRAY_GROW (label_to_block_map
, 3 * uid
/ 2);
2795 #ifdef ENABLE_CHECKING
2796 /* We're moving an existing label. Make sure that we've
2797 removed it from the old block. */
2798 if (bb
&& VARRAY_BB (label_to_block_map
, uid
))
2802 VARRAY_BB (label_to_block_map
, uid
) = bb
;
2808 /* Insert statement (or statement list) T before the statement
2809 pointed-to by iterator I. M specifies how to update iterator I
2810 after insertion (see enum bsi_iterator_update). */
2813 bsi_insert_before (block_stmt_iterator
*i
, tree t
, enum bsi_iterator_update m
)
2815 set_bb_for_stmt (t
, i
->bb
);
2817 tsi_link_before (&i
->tsi
, t
, m
);
2821 /* Insert statement (or statement list) T after the statement
2822 pointed-to by iterator I. M specifies how to update iterator I
2823 after insertion (see enum bsi_iterator_update). */
2826 bsi_insert_after (block_stmt_iterator
*i
, tree t
, enum bsi_iterator_update m
)
2828 set_bb_for_stmt (t
, i
->bb
);
2830 tsi_link_after (&i
->tsi
, t
, m
);
2834 /* Remove the statement pointed to by iterator I. The iterator is updated
2835 to the next statement. */
2838 bsi_remove (block_stmt_iterator
*i
)
2840 tree t
= bsi_stmt (*i
);
2841 set_bb_for_stmt (t
, NULL
);
2843 tsi_delink (&i
->tsi
);
2847 /* Move the statement at FROM so it comes right after the statement at TO. */
2850 bsi_move_after (block_stmt_iterator
*from
, block_stmt_iterator
*to
)
2852 tree stmt
= bsi_stmt (*from
);
2854 bsi_insert_after (to
, stmt
, BSI_SAME_STMT
);
2858 /* Move the statement at FROM so it comes right before the statement at TO. */
2861 bsi_move_before (block_stmt_iterator
*from
, block_stmt_iterator
*to
)
2863 tree stmt
= bsi_stmt (*from
);
2865 bsi_insert_before (to
, stmt
, BSI_SAME_STMT
);
2869 /* Move the statement at FROM to the end of basic block BB. */
2872 bsi_move_to_bb_end (block_stmt_iterator
*from
, basic_block bb
)
2874 block_stmt_iterator last
= bsi_last (bb
);
2876 /* Have to check bsi_end_p because it could be an empty block. */
2877 if (!bsi_end_p (last
) && is_ctrl_stmt (bsi_stmt (last
)))
2878 bsi_move_before (from
, &last
);
2880 bsi_move_after (from
, &last
);
2884 /* Replace the contents of the statement pointed to by iterator BSI
2885 with STMT. If PRESERVE_EH_INFO is true, the exception handling
2886 information of the original statement is preserved. */
2889 bsi_replace (const block_stmt_iterator
*bsi
, tree stmt
, bool preserve_eh_info
)
2892 tree orig_stmt
= bsi_stmt (*bsi
);
2894 SET_EXPR_LOCUS (stmt
, EXPR_LOCUS (orig_stmt
));
2895 set_bb_for_stmt (stmt
, bsi
->bb
);
2897 /* Preserve EH region information from the original statement, if
2898 requested by the caller. */
2899 if (preserve_eh_info
)
2901 eh_region
= lookup_stmt_eh_region (orig_stmt
);
2903 add_stmt_to_eh_region (stmt
, eh_region
);
2906 *bsi_stmt_ptr (*bsi
) = stmt
;
2911 /* Insert the statement pointed-to by BSI into edge E. Every attempt
2912 is made to place the statement in an existing basic block, but
2913 sometimes that isn't possible. When it isn't possible, the edge is
2914 split and the statement is added to the new block.
2916 In all cases, the returned *BSI points to the correct location. The
2917 return value is true if insertion should be done after the location,
2918 or false if it should be done before the location. */
2921 tree_find_edge_insert_loc (edge e
, block_stmt_iterator
*bsi
)
2923 basic_block dest
, src
;
2929 /* If the destination has one predecessor which has no PHI nodes,
2930 insert there. Except for the exit block.
2932 The requirement for no PHI nodes could be relaxed. Basically we
2933 would have to examine the PHIs to prove that none of them used
2934 the value set by the statement we want to insert on E. That
2935 hardly seems worth the effort. */
2936 if (dest
->pred
->pred_next
== NULL
2937 && ! phi_nodes (dest
)
2938 && dest
!= EXIT_BLOCK_PTR
)
2940 *bsi
= bsi_start (dest
);
2941 if (bsi_end_p (*bsi
))
2944 /* Make sure we insert after any leading labels. */
2945 tmp
= bsi_stmt (*bsi
);
2946 while (TREE_CODE (tmp
) == LABEL_EXPR
)
2949 if (bsi_end_p (*bsi
))
2951 tmp
= bsi_stmt (*bsi
);
2954 if (bsi_end_p (*bsi
))
2956 *bsi
= bsi_last (dest
);
2963 /* If the source has one successor, the edge is not abnormal and
2964 the last statement does not end a basic block, insert there.
2965 Except for the entry block. */
2967 if ((e
->flags
& EDGE_ABNORMAL
) == 0
2968 && src
->succ
->succ_next
== NULL
2969 && src
!= ENTRY_BLOCK_PTR
)
2971 *bsi
= bsi_last (src
);
2972 if (bsi_end_p (*bsi
))
2975 tmp
= bsi_stmt (*bsi
);
2976 if (!stmt_ends_bb_p (tmp
))
2979 /* Insert code just before returning the value. We may need to decompose
2980 the return in the case it contains non-trivial operand. */
2981 if (TREE_CODE (tmp
) == RETURN_EXPR
)
2983 tree op
= TREE_OPERAND (tmp
, 0);
2984 if (!is_gimple_val (op
))
2986 if (TREE_CODE (op
) != MODIFY_EXPR
)
2988 bsi_insert_before (bsi
, op
, BSI_NEW_STMT
);
2989 TREE_OPERAND (tmp
, 0) = TREE_OPERAND (op
, 0);
2996 /* Otherwise, create a new basic block, and split this edge. */
2997 dest
= split_edge (e
);
3003 /* This routine will commit all pending edge insertions, creating any new
3004 basic blocks which are necessary.
3006 If specified, NEW_BLOCKS returns a count of the number of new basic
3007 blocks which were created. */
3010 bsi_commit_edge_inserts (int *new_blocks
)
3016 blocks
= n_basic_blocks
;
3018 bsi_commit_edge_inserts_1 (ENTRY_BLOCK_PTR
->succ
);
3021 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
3022 bsi_commit_edge_inserts_1 (e
);
3025 *new_blocks
= n_basic_blocks
- blocks
;
3029 /* Commit insertions pending at edge E. */
3032 bsi_commit_edge_inserts_1 (edge e
)
3034 if (PENDING_STMT (e
))
3036 block_stmt_iterator bsi
;
3037 tree stmt
= PENDING_STMT (e
);
3039 PENDING_STMT (e
) = NULL_TREE
;
3041 if (tree_find_edge_insert_loc (e
, &bsi
))
3042 bsi_insert_after (&bsi
, stmt
, BSI_NEW_STMT
);
3044 bsi_insert_before (&bsi
, stmt
, BSI_NEW_STMT
);
3049 /* Add STMT to the pending list of edge E. No actual insertion is
3050 made until a call to bsi_commit_edge_inserts () is made. */
3053 bsi_insert_on_edge (edge e
, tree stmt
)
3055 append_to_statement_list (stmt
, &PENDING_STMT (e
));
3059 /*---------------------------------------------------------------------------
3060 Tree specific functions for CFG manipulation
3061 ---------------------------------------------------------------------------*/
3063 /* Split a (typically critical) edge EDGE_IN. Return the new block.
3064 Abort on abnormal edges. */
3067 tree_split_edge (edge edge_in
)
3069 basic_block new_bb
, after_bb
, dest
, src
;
3074 /* Abnormal edges cannot be split. */
3075 if (edge_in
->flags
& EDGE_ABNORMAL
)
3079 dest
= edge_in
->dest
;
3081 /* Place the new block in the block list. Try to keep the new block
3082 near its "logical" location. This is of most help to humans looking
3083 at debugging dumps. */
3084 for (e
= dest
->pred
; e
; e
= e
->pred_next
)
3085 if (e
->src
->next_bb
== dest
)
3088 after_bb
= dest
->prev_bb
;
3090 after_bb
= edge_in
->src
;
3092 new_bb
= create_empty_bb (after_bb
);
3093 new_edge
= make_edge (new_bb
, dest
, EDGE_FALLTHRU
);
3095 /* Find all the PHI arguments on the original edge, and change them to
3096 the new edge. Do it before redirection, so that the argument does not
3098 for (phi
= phi_nodes (dest
); phi
; phi
= PHI_CHAIN (phi
))
3100 num_elem
= PHI_NUM_ARGS (phi
);
3101 for (i
= 0; i
< num_elem
; i
++)
3102 if (PHI_ARG_EDGE (phi
, i
) == edge_in
)
3104 PHI_ARG_EDGE (phi
, i
) = new_edge
;
3109 if (!redirect_edge_and_branch (edge_in
, new_bb
))
3112 if (PENDING_STMT (edge_in
))
3119 /* Return true when BB has label LABEL in it. */
3122 has_label_p (basic_block bb
, tree label
)
3124 block_stmt_iterator bsi
;
3126 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
3128 tree stmt
= bsi_stmt (bsi
);
3130 if (TREE_CODE (stmt
) != LABEL_EXPR
)
3132 if (LABEL_EXPR_LABEL (stmt
) == label
)
3139 /* Callback for walk_tree, check that all elements with address taken are
3140 properly noticed as such. */
3143 verify_expr (tree
*tp
, int *walk_subtrees
, void *data ATTRIBUTE_UNUSED
)
3150 /* Check operand N for being valid GIMPLE and give error MSG if not.
3151 We check for constants explicitly since they are not considered
3152 gimple invariants if they overflowed. */
3153 #define CHECK_OP(N, MSG) \
3154 do { if (TREE_CODE_CLASS (TREE_CODE (TREE_OPERAND (t, N))) != 'c' \
3155 && !is_gimple_val (TREE_OPERAND (t, N))) \
3156 { error (MSG); return TREE_OPERAND (t, N); }} while (0)
3158 switch (TREE_CODE (t
))
3161 if (SSA_NAME_IN_FREE_LIST (t
))
3163 error ("SSA name in freelist but still referenced");
3169 x
= TREE_OPERAND (t
, 0);
3170 if (TREE_CODE (x
) == BIT_FIELD_REF
3171 && is_gimple_reg (TREE_OPERAND (x
, 0)))
3173 error ("GIMPLE register modified with BIT_FIELD_REF");
3179 /* Skip any references (they will be checked when we recurse down the
3180 tree) and ensure that any variable used as a prefix is marked
3182 for (x
= TREE_OPERAND (t
, 0);
3183 (handled_component_p (x
)
3184 || TREE_CODE (x
) == REALPART_EXPR
3185 || TREE_CODE (x
) == IMAGPART_EXPR
);
3186 x
= TREE_OPERAND (x
, 0))
3189 if (TREE_CODE (x
) != VAR_DECL
&& TREE_CODE (x
) != PARM_DECL
)
3191 if (!TREE_ADDRESSABLE (x
))
3193 error ("address taken, but ADDRESSABLE bit not set");
3199 x
= TREE_OPERAND (t
, 0);
3200 if (TREE_CODE (TREE_TYPE (x
)) != BOOLEAN_TYPE
)
3202 error ("non-boolean used in condition");
3209 case FIX_TRUNC_EXPR
:
3211 case FIX_FLOOR_EXPR
:
3212 case FIX_ROUND_EXPR
:
3217 case NON_LVALUE_EXPR
:
3218 case TRUTH_NOT_EXPR
:
3219 CHECK_OP (0, "Invalid operand to unary operator");
3226 case ARRAY_RANGE_REF
:
3228 case VIEW_CONVERT_EXPR
:
3229 /* We have a nest of references. Verify that each of the operands
3230 that determine where to reference is either a constant or a variable,
3231 verify that the base is valid, and then show we've already checked
3233 while (TREE_CODE (t
) == REALPART_EXPR
|| TREE_CODE (t
) == IMAGPART_EXPR
3234 || handled_component_p (t
))
3236 if (TREE_CODE (t
) == COMPONENT_REF
&& TREE_OPERAND (t
, 2))
3237 CHECK_OP (2, "Invalid COMPONENT_REF offset operator");
3238 else if (TREE_CODE (t
) == ARRAY_REF
3239 || TREE_CODE (t
) == ARRAY_RANGE_REF
)
3241 CHECK_OP (1, "Invalid array index.");
3242 if (TREE_OPERAND (t
, 2))
3243 CHECK_OP (2, "Invalid array lower bound.");
3244 if (TREE_OPERAND (t
, 3))
3245 CHECK_OP (3, "Invalid array stride.");
3247 else if (TREE_CODE (t
) == BIT_FIELD_REF
)
3249 CHECK_OP (1, "Invalid operand to BIT_FIELD_REF");
3250 CHECK_OP (2, "Invalid operand to BIT_FIELD_REF");
3253 t
= TREE_OPERAND (t
, 0);
3256 if (TREE_CODE_CLASS (TREE_CODE (t
)) != 'c'
3257 && !is_gimple_lvalue (t
))
3259 error ("Invalid reference prefix.");
3271 case UNORDERED_EXPR
:
3282 case TRUNC_DIV_EXPR
:
3284 case FLOOR_DIV_EXPR
:
3285 case ROUND_DIV_EXPR
:
3286 case TRUNC_MOD_EXPR
:
3288 case FLOOR_MOD_EXPR
:
3289 case ROUND_MOD_EXPR
:
3291 case EXACT_DIV_EXPR
:
3301 CHECK_OP (0, "Invalid operand to binary operator");
3302 CHECK_OP (1, "Invalid operand to binary operator");
3314 /* Verify STMT, return true if STMT is not in GIMPLE form.
3315 TODO: Implement type checking. */
3318 verify_stmt (tree stmt
, bool last_in_block
)
3322 if (!is_gimple_stmt (stmt
))
3324 error ("Is not a valid GIMPLE statement.");
3328 addr
= walk_tree (&stmt
, verify_expr
, NULL
, NULL
);
3331 debug_generic_stmt (addr
);
3335 /* If the statement is marked as part of an EH region, then it is
3336 expected that the statement could throw. Verify that when we
3337 have optimizations that simplify statements such that we prove
3338 that they cannot throw, that we update other data structures
3340 if (lookup_stmt_eh_region (stmt
) >= 0)
3342 if (!tree_could_throw_p (stmt
))
3344 error ("Statement marked for throw, but doesn't.");
3347 if (!last_in_block
&& tree_can_throw_internal (stmt
))
3349 error ("Statement marked for throw in middle of block.");
3357 debug_generic_stmt (stmt
);
3362 /* Return true when the T can be shared. */
3365 tree_node_can_be_shared (tree t
)
3367 if (TYPE_P (t
) || DECL_P (t
)
3368 /* We check for constants explicitly since they are not considered
3369 gimple invariants if they overflowed. */
3370 || TREE_CODE_CLASS (TREE_CODE (t
)) == 'c'
3371 || is_gimple_min_invariant (t
)
3372 || TREE_CODE (t
) == SSA_NAME
)
3375 while (((TREE_CODE (t
) == ARRAY_REF
|| TREE_CODE (t
) == ARRAY_RANGE_REF
)
3376 /* We check for constants explicitly since they are not considered
3377 gimple invariants if they overflowed. */
3378 && (TREE_CODE_CLASS (TREE_CODE (TREE_OPERAND (t
, 1))) == 'c'
3379 || is_gimple_min_invariant (TREE_OPERAND (t
, 1))))
3380 || (TREE_CODE (t
) == COMPONENT_REF
3381 || TREE_CODE (t
) == REALPART_EXPR
3382 || TREE_CODE (t
) == IMAGPART_EXPR
))
3383 t
= TREE_OPERAND (t
, 0);
3392 /* Called via walk_trees. Verify tree sharing. */
3395 verify_node_sharing (tree
* tp
, int *walk_subtrees
, void *data
)
3397 htab_t htab
= (htab_t
) data
;
3400 if (tree_node_can_be_shared (*tp
))
3402 *walk_subtrees
= false;
3406 slot
= htab_find_slot (htab
, *tp
, INSERT
);
3415 /* Verify the GIMPLE statement chain. */
3421 block_stmt_iterator bsi
;
3426 timevar_push (TV_TREE_STMT_VERIFY
);
3427 htab
= htab_create (37, htab_hash_pointer
, htab_eq_pointer
, NULL
);
3434 for (phi
= phi_nodes (bb
); phi
; phi
= PHI_CHAIN (phi
))
3436 int phi_num_args
= PHI_NUM_ARGS (phi
);
3438 for (i
= 0; i
< phi_num_args
; i
++)
3440 tree t
= PHI_ARG_DEF (phi
, i
);
3443 /* Addressable variables do have SSA_NAMEs but they
3444 are not considered gimple values. */
3445 if (TREE_CODE (t
) != SSA_NAME
3446 && TREE_CODE (t
) != FUNCTION_DECL
3447 && !is_gimple_val (t
))
3449 error ("PHI def is not a GIMPLE value");
3450 debug_generic_stmt (phi
);
3451 debug_generic_stmt (t
);
3455 addr
= walk_tree (&t
, verify_expr
, NULL
, NULL
);
3458 debug_generic_stmt (addr
);
3462 addr
= walk_tree (&t
, verify_node_sharing
, htab
, NULL
);
3465 error ("Incorrect sharing of tree nodes");
3466 debug_generic_stmt (phi
);
3467 debug_generic_stmt (addr
);
3473 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); )
3475 tree stmt
= bsi_stmt (bsi
);
3477 err
|= verify_stmt (stmt
, bsi_end_p (bsi
));
3478 addr
= walk_tree (&stmt
, verify_node_sharing
, htab
, NULL
);
3481 error ("Incorrect sharing of tree nodes");
3482 debug_generic_stmt (stmt
);
3483 debug_generic_stmt (addr
);
3490 internal_error ("verify_stmts failed.");
3493 timevar_pop (TV_TREE_STMT_VERIFY
);
3497 /* Verifies that the flow information is OK. */
3500 tree_verify_flow_info (void)
3504 block_stmt_iterator bsi
;
3508 if (ENTRY_BLOCK_PTR
->stmt_list
)
3510 error ("ENTRY_BLOCK has a statement list associated with it\n");
3514 if (EXIT_BLOCK_PTR
->stmt_list
)
3516 error ("EXIT_BLOCK has a statement list associated with it\n");
3520 for (e
= EXIT_BLOCK_PTR
->pred
; e
; e
= e
->pred_next
)
3521 if (e
->flags
& EDGE_FALLTHRU
)
3523 error ("Fallthru to exit from bb %d\n", e
->src
->index
);
3529 bool found_ctrl_stmt
= false;
3531 /* Skip labels on the start of basic block. */
3532 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
3534 if (TREE_CODE (bsi_stmt (bsi
)) != LABEL_EXPR
)
3537 if (label_to_block (LABEL_EXPR_LABEL (bsi_stmt (bsi
))) != bb
)
3539 error ("Label %s to block does not match in bb %d\n",
3540 IDENTIFIER_POINTER (DECL_NAME (bsi_stmt (bsi
))),
3545 if (decl_function_context (LABEL_EXPR_LABEL (bsi_stmt (bsi
)))
3546 != current_function_decl
)
3548 error ("Label %s has incorrect context in bb %d\n",
3549 IDENTIFIER_POINTER (DECL_NAME (bsi_stmt (bsi
))),
3555 /* Verify that body of basic block BB is free of control flow. */
3556 for (; !bsi_end_p (bsi
); bsi_next (&bsi
))
3558 tree stmt
= bsi_stmt (bsi
);
3560 if (found_ctrl_stmt
)
3562 error ("Control flow in the middle of basic block %d\n",
3567 if (stmt_ends_bb_p (stmt
))
3568 found_ctrl_stmt
= true;
3570 if (TREE_CODE (stmt
) == LABEL_EXPR
)
3572 error ("Label %s in the middle of basic block %d\n",
3573 IDENTIFIER_POINTER (DECL_NAME (stmt
)),
3578 bsi
= bsi_last (bb
);
3579 if (bsi_end_p (bsi
))
3582 stmt
= bsi_stmt (bsi
);
3584 if (is_ctrl_stmt (stmt
))
3586 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
3587 if (e
->flags
& EDGE_FALLTHRU
)
3589 error ("Fallthru edge after a control statement in bb %d \n",
3595 switch (TREE_CODE (stmt
))
3601 if (TREE_CODE (COND_EXPR_THEN (stmt
)) != GOTO_EXPR
3602 || TREE_CODE (COND_EXPR_ELSE (stmt
)) != GOTO_EXPR
)
3604 error ("Structured COND_EXPR at the end of bb %d\n", bb
->index
);
3608 extract_true_false_edges_from_block (bb
, &true_edge
, &false_edge
);
3610 if (!true_edge
|| !false_edge
3611 || !(true_edge
->flags
& EDGE_TRUE_VALUE
)
3612 || !(false_edge
->flags
& EDGE_FALSE_VALUE
)
3613 || (true_edge
->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
))
3614 || (false_edge
->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
))
3615 || bb
->succ
->succ_next
->succ_next
)
3617 error ("Wrong outgoing edge flags at end of bb %d\n",
3622 if (!has_label_p (true_edge
->dest
,
3623 GOTO_DESTINATION (COND_EXPR_THEN (stmt
))))
3625 error ("`then' label does not match edge at end of bb %d\n",
3630 if (!has_label_p (false_edge
->dest
,
3631 GOTO_DESTINATION (COND_EXPR_ELSE (stmt
))))
3633 error ("`else' label does not match edge at end of bb %d\n",
3641 if (simple_goto_p (stmt
))
3643 error ("Explicit goto at end of bb %d\n", bb
->index
);
3648 /* FIXME. We should double check that the labels in the
3649 destination blocks have their address taken. */
3650 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
3651 if ((e
->flags
& (EDGE_FALLTHRU
| EDGE_TRUE_VALUE
3652 | EDGE_FALSE_VALUE
))
3653 || !(e
->flags
& EDGE_ABNORMAL
))
3655 error ("Wrong outgoing edge flags at end of bb %d\n",
3663 if (!bb
->succ
|| bb
->succ
->succ_next
3664 || (bb
->succ
->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
3665 | EDGE_TRUE_VALUE
| EDGE_FALSE_VALUE
)))
3667 error ("Wrong outgoing edge flags at end of bb %d\n", bb
->index
);
3670 if (bb
->succ
->dest
!= EXIT_BLOCK_PTR
)
3672 error ("Return edge does not point to exit in bb %d\n",
3685 vec
= SWITCH_LABELS (stmt
);
3686 n
= TREE_VEC_LENGTH (vec
);
3688 /* Mark all the destination basic blocks. */
3689 for (i
= 0; i
< n
; ++i
)
3691 tree lab
= CASE_LABEL (TREE_VEC_ELT (vec
, i
));
3692 basic_block label_bb
= label_to_block (lab
);
3694 if (label_bb
->aux
&& label_bb
->aux
!= (void *)1)
3696 label_bb
->aux
= (void *)1;
3699 /* Verify that the case labels are sorted. */
3700 prev
= TREE_VEC_ELT (vec
, 0);
3701 for (i
= 1; i
< n
- 1; ++i
)
3703 tree c
= TREE_VEC_ELT (vec
, i
);
3706 error ("Found default case not at end of case vector");
3710 if (! tree_int_cst_lt (CASE_LOW (prev
), CASE_LOW (c
)))
3712 error ("Case labels not sorted:\n ");
3713 print_generic_expr (stderr
, prev
, 0);
3714 fprintf (stderr
," is greater than ");
3715 print_generic_expr (stderr
, c
, 0);
3716 fprintf (stderr
," but comes before it.\n");
3721 if (CASE_LOW (TREE_VEC_ELT (vec
, n
- 1)))
3723 error ("No default case found at end of case vector");
3727 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
3731 error ("Extra outgoing edge %d->%d\n",
3732 bb
->index
, e
->dest
->index
);
3735 e
->dest
->aux
= (void *)2;
3736 if ((e
->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
3737 | EDGE_TRUE_VALUE
| EDGE_FALSE_VALUE
)))
3739 error ("Wrong outgoing edge flags at end of bb %d\n",
3745 /* Check that we have all of them. */
3746 for (i
= 0; i
< n
; ++i
)
3748 tree lab
= CASE_LABEL (TREE_VEC_ELT (vec
, i
));
3749 basic_block label_bb
= label_to_block (lab
);
3751 if (label_bb
->aux
!= (void *)2)
3753 error ("Missing edge %i->%i\n",
3754 bb
->index
, label_bb
->index
);
3759 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
3760 e
->dest
->aux
= (void *)0;
3767 if (dom_computed
[CDI_DOMINATORS
] >= DOM_NO_FAST_QUERY
)
3768 verify_dominators (CDI_DOMINATORS
);
3774 /* Updates phi nodes after creating forwarder block joined
3775 by edge FALLTHRU. */
3778 tree_make_forwarder_block (edge fallthru
)
3781 basic_block dummy
, bb
;
3782 tree phi
, new_phi
, var
, prev
, next
;
3784 dummy
= fallthru
->src
;
3785 bb
= fallthru
->dest
;
3787 if (!bb
->pred
->pred_next
)
3790 /* If we redirected a branch we must create new phi nodes at the
3792 for (phi
= phi_nodes (dummy
); phi
; phi
= PHI_CHAIN (phi
))
3794 var
= PHI_RESULT (phi
);
3795 new_phi
= create_phi_node (var
, bb
);
3796 SSA_NAME_DEF_STMT (var
) = new_phi
;
3797 SET_PHI_RESULT (phi
, make_ssa_name (SSA_NAME_VAR (var
), phi
));
3798 add_phi_arg (&new_phi
, PHI_RESULT (phi
), fallthru
);
3801 /* Ensure that the PHI node chain is in the same order. */
3803 for (phi
= phi_nodes (bb
); phi
; phi
= next
)
3805 next
= PHI_CHAIN (phi
);
3806 PHI_CHAIN (phi
) = prev
;
3809 set_phi_nodes (bb
, prev
);
3811 /* Add the arguments we have stored on edges. */
3812 for (e
= bb
->pred
; e
; e
= e
->pred_next
)
3817 for (phi
= phi_nodes (bb
), var
= PENDING_STMT (e
);
3819 phi
= PHI_CHAIN (phi
), var
= TREE_CHAIN (var
))
3820 add_phi_arg (&phi
, TREE_VALUE (var
), e
);
3822 PENDING_STMT (e
) = NULL
;
3827 /* Return true if basic block BB does nothing except pass control
3828 flow to another block and that we can safely insert a label at
3829 the start of the successor block. */
3832 tree_forwarder_block_p (basic_block bb
)
3834 block_stmt_iterator bsi
;
3837 /* If we have already determined that this block is not forwardable,
3838 then no further checks are necessary. */
3839 if (! bb_ann (bb
)->forwardable
)
3842 /* BB must have a single outgoing normal edge. Otherwise it can not be
3843 a forwarder block. */
3845 || bb
->succ
->succ_next
3846 || bb
->succ
->dest
== EXIT_BLOCK_PTR
3847 || (bb
->succ
->flags
& EDGE_ABNORMAL
)
3848 || bb
== ENTRY_BLOCK_PTR
)
3850 bb_ann (bb
)->forwardable
= 0;
3854 /* Successors of the entry block are not forwarders. */
3855 for (e
= ENTRY_BLOCK_PTR
->succ
; e
; e
= e
->succ_next
)
3858 bb_ann (bb
)->forwardable
= 0;
3862 /* BB can not have any PHI nodes. This could potentially be relaxed
3863 early in compilation if we re-rewrote the variables appearing in
3864 any PHI nodes in forwarder blocks. */
3867 bb_ann (bb
)->forwardable
= 0;
3871 /* Now walk through the statements. We can ignore labels, anything else
3872 means this is not a forwarder block. */
3873 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
3875 tree stmt
= bsi_stmt (bsi
);
3877 switch (TREE_CODE (stmt
))
3880 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt
)))
3885 bb_ann (bb
)->forwardable
= 0;
3894 /* Thread jumps over empty statements.
3896 This code should _not_ thread over obviously equivalent conditions
3897 as that requires nontrivial updates to the SSA graph. */
3902 edge e
, next
, last
, old
;
3903 basic_block bb
, dest
, tmp
;
3906 bool retval
= false;
3909 bb_ann (bb
)->forwardable
= 1;
3911 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
, EXIT_BLOCK_PTR
, next_bb
)
3913 /* Don't waste time on unreachable blocks. */
3917 /* Nor on forwarders. */
3918 if (tree_forwarder_block_p (bb
))
3921 /* This block is now part of a forwarding path, mark it as not
3922 forwardable so that we can detect loops. This bit will be
3924 bb_ann (bb
)->forwardable
= 0;
3926 /* Examine each of our block's successors to see if it is
3928 for (e
= bb
->succ
; e
; e
= next
)
3930 next
= e
->succ_next
;
3932 /* If the edge is abnormal or its destination is not
3933 forwardable, then there's nothing to do. */
3934 if ((e
->flags
& EDGE_ABNORMAL
)
3935 || !tree_forwarder_block_p (e
->dest
))
3938 /* Now walk through as many forwarder block as possible to
3939 find the ultimate destination we want to thread our jump
3941 last
= e
->dest
->succ
;
3942 bb_ann (e
->dest
)->forwardable
= 0;
3943 for (dest
= e
->dest
->succ
->dest
;
3944 tree_forwarder_block_p (dest
);
3946 dest
= dest
->succ
->dest
)
3948 /* An infinite loop detected. We redirect the edge anyway, so
3949 that the loop is shrunk into single basic block. */
3950 if (!bb_ann (dest
)->forwardable
)
3953 if (dest
->succ
->dest
== EXIT_BLOCK_PTR
)
3956 bb_ann (dest
)->forwardable
= 0;
3959 /* Reset the forwardable marks to 1. */
3962 tmp
= tmp
->succ
->dest
)
3963 bb_ann (tmp
)->forwardable
= 1;
3965 if (dest
== e
->dest
)
3968 old
= find_edge (bb
, dest
);
3971 /* If there already is an edge, check whether the values
3972 in phi nodes differ. */
3973 if (!phi_alternatives_equal (dest
, last
, old
))
3975 /* The previous block is forwarder. Redirect our jump
3976 to that target instead since we know it has no PHI
3977 nodes that will need updating. */
3980 /* That might mean that no forwarding at all is possible. */
3981 if (dest
== e
->dest
)
3984 old
= find_edge (bb
, dest
);
3988 /* Perform the redirection. */
3990 e
= redirect_edge_and_branch (e
, dest
);
3992 /* TODO -- updating dominators in this case is simple. */
3993 free_dominance_info (CDI_DOMINATORS
);
3997 /* Update PHI nodes. We know that the new argument should
3998 have the same value as the argument associated with LAST.
3999 Otherwise we would have changed our target block above. */
4000 for (phi
= phi_nodes (dest
); phi
; phi
= PHI_CHAIN (phi
))
4002 arg
= phi_arg_from_edge (phi
, last
);
4005 add_phi_arg (&phi
, PHI_ARG_DEF (phi
, arg
), e
);
4010 /* Reset the forwardable bit on our block since it's no longer in
4011 a forwarding chain path. */
4012 bb_ann (bb
)->forwardable
= 1;
4019 /* Return a non-special label in the head of basic block BLOCK.
4020 Create one if it doesn't exist. */
4023 tree_block_label (basic_block bb
)
4025 block_stmt_iterator i
, s
= bsi_start (bb
);
4029 for (i
= s
; !bsi_end_p (i
); first
= false, bsi_next (&i
))
4031 stmt
= bsi_stmt (i
);
4032 if (TREE_CODE (stmt
) != LABEL_EXPR
)
4034 label
= LABEL_EXPR_LABEL (stmt
);
4035 if (!DECL_NONLOCAL (label
))
4038 bsi_move_before (&i
, &s
);
4043 label
= create_artificial_label ();
4044 stmt
= build1 (LABEL_EXPR
, void_type_node
, label
);
4045 bsi_insert_before (&s
, stmt
, BSI_NEW_STMT
);
4050 /* Attempt to perform edge redirection by replacing a possibly complex
4051 jump instruction by a goto or by removing the jump completely.
4052 This can apply only if all edges now point to the same block. The
4053 parameters and return values are equivalent to
4054 redirect_edge_and_branch. */
4057 tree_try_redirect_by_replacing_jump (edge e
, basic_block target
)
4059 basic_block src
= e
->src
;
4061 block_stmt_iterator b
;
4064 /* Verify that all targets will be TARGET. */
4065 for (tmp
= src
->succ
; tmp
; tmp
= tmp
->succ_next
)
4066 if (tmp
->dest
!= target
&& tmp
!= e
)
4075 stmt
= bsi_stmt (b
);
4077 if (TREE_CODE (stmt
) == COND_EXPR
4078 || TREE_CODE (stmt
) == SWITCH_EXPR
)
4081 e
= ssa_redirect_edge (e
, target
);
4082 e
->flags
= EDGE_FALLTHRU
;
4090 /* Redirect E to DEST. Return NULL on failure. Otherwise, return the
4091 edge representing the redirected branch. */
4094 tree_redirect_edge_and_branch (edge e
, basic_block dest
)
4096 basic_block bb
= e
->src
;
4097 block_stmt_iterator bsi
;
4101 if (e
->flags
& (EDGE_ABNORMAL_CALL
| EDGE_EH
))
4104 if (e
->src
!= ENTRY_BLOCK_PTR
4105 && (ret
= tree_try_redirect_by_replacing_jump (e
, dest
)))
4108 if (e
->dest
== dest
)
4111 label
= tree_block_label (dest
);
4113 bsi
= bsi_last (bb
);
4114 stmt
= bsi_end_p (bsi
) ? NULL
: bsi_stmt (bsi
);
4116 switch (stmt
? TREE_CODE (stmt
) : ERROR_MARK
)
4119 stmt
= (e
->flags
& EDGE_TRUE_VALUE
4120 ? COND_EXPR_THEN (stmt
)
4121 : COND_EXPR_ELSE (stmt
));
4122 GOTO_DESTINATION (stmt
) = label
;
4126 /* No non-abnormal edges should lead from a non-simple goto, and
4127 simple ones should be represented implicitly. */
4132 tree vec
= SWITCH_LABELS (stmt
);
4133 size_t i
, n
= TREE_VEC_LENGTH (vec
);
4135 for (i
= 0; i
< n
; ++i
)
4137 tree elt
= TREE_VEC_ELT (vec
, i
);
4138 if (label_to_block (CASE_LABEL (elt
)) == e
->dest
)
4139 CASE_LABEL (elt
) = label
;
4146 e
->flags
|= EDGE_FALLTHRU
;
4150 /* Otherwise it must be a fallthru edge, and we don't need to
4151 do anything besides redirecting it. */
4152 if (!(e
->flags
& EDGE_FALLTHRU
))
4157 /* Update/insert PHI nodes as necessary. */
4159 /* Now update the edges in the CFG. */
4160 e
= ssa_redirect_edge (e
, dest
);
4166 /* Simple wrapper, as we can always redirect fallthru edges. */
4169 tree_redirect_edge_and_branch_force (edge e
, basic_block dest
)
4171 e
= tree_redirect_edge_and_branch (e
, dest
);
4179 /* Splits basic block BB after statement STMT (but at least after the
4180 labels). If STMT is NULL, BB is split just after the labels. */
4183 tree_split_block (basic_block bb
, void *stmt
)
4185 block_stmt_iterator bsi
, bsi_tgt
;
4190 new_bb
= create_empty_bb (bb
);
4192 /* Redirect the outgoing edges. */
4193 new_bb
->succ
= bb
->succ
;
4195 for (e
= new_bb
->succ
; e
; e
= e
->succ_next
)
4198 if (stmt
&& TREE_CODE ((tree
) stmt
) == LABEL_EXPR
)
4201 /* Move everything from BSI to the new basic block. */
4202 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
4204 act
= bsi_stmt (bsi
);
4205 if (TREE_CODE (act
) == LABEL_EXPR
)
4218 bsi_tgt
= bsi_start (new_bb
);
4219 while (!bsi_end_p (bsi
))
4221 act
= bsi_stmt (bsi
);
4223 bsi_insert_after (&bsi_tgt
, act
, BSI_NEW_STMT
);
4230 /* Moves basic block BB after block AFTER. */
4233 tree_move_block_after (basic_block bb
, basic_block after
)
4235 if (bb
->prev_bb
== after
)
4239 link_block (bb
, after
);
4245 /* Return true if basic_block can be duplicated. */
4248 tree_can_duplicate_bb_p (basic_block bb ATTRIBUTE_UNUSED
)
4254 /* Create a duplicate of the basic block BB. NOTE: This does not
4255 preserve SSA form. */
4258 tree_duplicate_bb (basic_block bb
)
4261 block_stmt_iterator bsi
, bsi_tgt
;
4263 new_bb
= create_empty_bb (EXIT_BLOCK_PTR
->prev_bb
);
4264 bsi_tgt
= bsi_start (new_bb
);
4265 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
4267 tree stmt
= bsi_stmt (bsi
);
4270 if (TREE_CODE (stmt
) == LABEL_EXPR
)
4273 copy
= unshare_expr (stmt
);
4275 /* Copy also the virtual operands. */
4276 get_stmt_ann (copy
);
4277 copy_virtual_operands (copy
, stmt
);
4279 bsi_insert_after (&bsi_tgt
, copy
, BSI_NEW_STMT
);
4286 /* Dump FUNCTION_DECL FN to file FILE using FLAGS (see TDF_* in tree.h) */
4289 dump_function_to_file (tree fn
, FILE *file
, int flags
)
4291 tree arg
, vars
, var
;
4292 bool ignore_topmost_bind
= false, any_var
= false;
4296 fprintf (file
, "%s (", lang_hooks
.decl_printable_name (fn
, 2));
4298 arg
= DECL_ARGUMENTS (fn
);
4301 print_generic_expr (file
, arg
, dump_flags
);
4302 if (TREE_CHAIN (arg
))
4303 fprintf (file
, ", ");
4304 arg
= TREE_CHAIN (arg
);
4306 fprintf (file
, ")\n");
4308 if (flags
& TDF_RAW
)
4310 dump_node (fn
, TDF_SLIM
| flags
, file
);
4314 /* When GIMPLE is lowered, the variables are no longer available in
4315 BIND_EXPRs, so display them separately. */
4316 if (cfun
&& cfun
->unexpanded_var_list
)
4318 ignore_topmost_bind
= true;
4320 fprintf (file
, "{\n");
4321 for (vars
= cfun
->unexpanded_var_list
; vars
; vars
= TREE_CHAIN (vars
))
4323 var
= TREE_VALUE (vars
);
4325 print_generic_decl (file
, var
, flags
);
4326 fprintf (file
, "\n");
4332 if (basic_block_info
)
4334 /* Make a CFG based dump. */
4335 if (!ignore_topmost_bind
)
4336 fprintf (file
, "{\n");
4338 if (any_var
&& n_basic_blocks
)
4339 fprintf (file
, "\n");
4342 dump_generic_bb (file
, bb
, 2, flags
);
4344 fprintf (file
, "}\n");
4350 /* Make a tree based dump. */
4351 chain
= DECL_SAVED_TREE (fn
);
4353 if (TREE_CODE (chain
) == BIND_EXPR
)
4355 if (ignore_topmost_bind
)
4357 chain
= BIND_EXPR_BODY (chain
);
4365 if (!ignore_topmost_bind
)
4366 fprintf (file
, "{\n");
4371 fprintf (file
, "\n");
4373 print_generic_stmt_indented (file
, chain
, flags
, indent
);
4374 if (ignore_topmost_bind
)
4375 fprintf (file
, "}\n");
4378 fprintf (file
, "\n\n");
4382 /* Pretty print of the loops intermediate representation. */
4383 static void print_loop (FILE *, struct loop
*, int);
4384 static void print_pred_bbs (FILE *, edge
);
4385 static void print_succ_bbs (FILE *, edge
);
4388 /* Print the predecessors indexes of edge E on FILE. */
4391 print_pred_bbs (FILE *file
, edge e
)
4396 else if (e
->pred_next
== NULL
)
4397 fprintf (file
, "bb_%d", e
->src
->index
);
4401 fprintf (file
, "bb_%d, ", e
->src
->index
);
4402 print_pred_bbs (file
, e
->pred_next
);
4407 /* Print the successors indexes of edge E on FILE. */
4410 print_succ_bbs (FILE *file
, edge e
)
4414 else if (e
->succ_next
== NULL
)
4415 fprintf (file
, "bb_%d", e
->dest
->index
);
4418 fprintf (file
, "bb_%d, ", e
->dest
->index
);
4419 print_succ_bbs (file
, e
->succ_next
);
4424 /* Pretty print LOOP on FILE, indented INDENT spaces. */
4427 print_loop (FILE *file
, struct loop
*loop
, int indent
)
4435 s_indent
= (char *) alloca ((size_t) indent
+ 1);
4436 memset ((void *) s_indent
, ' ', (size_t) indent
);
4437 s_indent
[indent
] = '\0';
4439 /* Print the loop's header. */
4440 fprintf (file
, "%sloop_%d\n", s_indent
, loop
->num
);
4442 /* Print the loop's body. */
4443 fprintf (file
, "%s{\n", s_indent
);
4445 if (bb
->loop_father
== loop
)
4447 /* Print the basic_block's header. */
4448 fprintf (file
, "%s bb_%d (preds = {", s_indent
, bb
->index
);
4449 print_pred_bbs (file
, bb
->pred
);
4450 fprintf (file
, "}, succs = {");
4451 print_succ_bbs (file
, bb
->succ
);
4452 fprintf (file
, "})\n");
4454 /* Print the basic_block's body. */
4455 fprintf (file
, "%s {\n", s_indent
);
4456 tree_dump_bb (bb
, file
, indent
+ 4);
4457 fprintf (file
, "%s }\n", s_indent
);
4460 print_loop (file
, loop
->inner
, indent
+ 2);
4461 fprintf (file
, "%s}\n", s_indent
);
4462 print_loop (file
, loop
->next
, indent
);
4466 /* Follow a CFG edge from the entry point of the program, and on entry
4467 of a loop, pretty print the loop structure on FILE. */
4470 print_loop_ir (FILE *file
)
4474 bb
= BASIC_BLOCK (0);
4475 if (bb
&& bb
->loop_father
)
4476 print_loop (file
, bb
->loop_father
, 0);
4480 /* Debugging loops structure at tree level. */
4483 debug_loop_ir (void)
4485 print_loop_ir (stderr
);
4489 /* Return true if BB ends with a call, possibly followed by some
4490 instructions that must stay with the call. Return false,
4494 tree_block_ends_with_call_p (basic_block bb
)
4496 block_stmt_iterator bsi
= bsi_last (bb
);
4497 return get_call_expr_in (bsi_stmt (bsi
)) != NULL
;
4501 /* Return true if BB ends with a conditional branch. Return false,
4505 tree_block_ends_with_condjump_p (basic_block bb
)
4507 tree stmt
= tsi_stmt (bsi_last (bb
).tsi
);
4508 return (TREE_CODE (stmt
) == COND_EXPR
);
4512 /* Return true if we need to add fake edge to exit at statement T.
4513 Helper function for tree_flow_call_edges_add. */
4516 need_fake_edge_p (tree t
)
4520 /* NORETURN and LONGJMP calls already have an edge to exit.
4521 CONST, PURE and ALWAYS_RETURN calls do not need one.
4522 We don't currently check for CONST and PURE here, although
4523 it would be a good idea, because those attributes are
4524 figured out from the RTL in mark_constant_function, and
4525 the counter incrementation code from -fprofile-arcs
4526 leads to different results from -fbranch-probabilities. */
4527 call
= get_call_expr_in (t
);
4529 && !(call_expr_flags (call
) &
4530 (ECF_NORETURN
| ECF_LONGJMP
| ECF_ALWAYS_RETURN
)))
4533 if (TREE_CODE (t
) == ASM_EXPR
4534 && (ASM_VOLATILE_P (t
) || ASM_INPUT_P (t
)))
4541 /* Add fake edges to the function exit for any non constant and non
4542 noreturn calls, volatile inline assembly in the bitmap of blocks
4543 specified by BLOCKS or to the whole CFG if BLOCKS is zero. Return
4544 the number of blocks that were split.
4546 The goal is to expose cases in which entering a basic block does
4547 not imply that all subsequent instructions must be executed. */
4550 tree_flow_call_edges_add (sbitmap blocks
)
4553 int blocks_split
= 0;
4554 int last_bb
= last_basic_block
;
4555 bool check_last_block
= false;
4557 if (n_basic_blocks
== 0)
4561 check_last_block
= true;
4563 check_last_block
= TEST_BIT (blocks
, EXIT_BLOCK_PTR
->prev_bb
->index
);
4565 /* In the last basic block, before epilogue generation, there will be
4566 a fallthru edge to EXIT. Special care is required if the last insn
4567 of the last basic block is a call because make_edge folds duplicate
4568 edges, which would result in the fallthru edge also being marked
4569 fake, which would result in the fallthru edge being removed by
4570 remove_fake_edges, which would result in an invalid CFG.
4572 Moreover, we can't elide the outgoing fake edge, since the block
4573 profiler needs to take this into account in order to solve the minimal
4574 spanning tree in the case that the call doesn't return.
4576 Handle this by adding a dummy instruction in a new last basic block. */
4577 if (check_last_block
)
4579 basic_block bb
= EXIT_BLOCK_PTR
->prev_bb
;
4580 block_stmt_iterator bsi
= bsi_last (bb
);
4582 if (!bsi_end_p (bsi
))
4585 if (need_fake_edge_p (t
))
4589 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
4590 if (e
->dest
== EXIT_BLOCK_PTR
)
4592 bsi_insert_on_edge (e
, build_empty_stmt ());
4593 bsi_commit_edge_inserts ((int *)NULL
);
4599 /* Now add fake edges to the function exit for any non constant
4600 calls since there is no way that we can determine if they will
4602 for (i
= 0; i
< last_bb
; i
++)
4604 basic_block bb
= BASIC_BLOCK (i
);
4605 block_stmt_iterator bsi
;
4606 tree stmt
, last_stmt
;
4611 if (blocks
&& !TEST_BIT (blocks
, i
))
4614 bsi
= bsi_last (bb
);
4615 if (!bsi_end_p (bsi
))
4617 last_stmt
= bsi_stmt (bsi
);
4620 stmt
= bsi_stmt (bsi
);
4621 if (need_fake_edge_p (stmt
))
4624 /* The handling above of the final block before the
4625 epilogue should be enough to verify that there is
4626 no edge to the exit block in CFG already.
4627 Calling make_edge in such case would cause us to
4628 mark that edge as fake and remove it later. */
4629 #ifdef ENABLE_CHECKING
4630 if (stmt
== last_stmt
)
4631 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
4632 if (e
->dest
== EXIT_BLOCK_PTR
)
4636 /* Note that the following may create a new basic block
4637 and renumber the existing basic blocks. */
4638 if (stmt
!= last_stmt
)
4640 e
= split_block (bb
, stmt
);
4644 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
4648 while (!bsi_end_p (bsi
));
4653 verify_flow_info ();
4655 return blocks_split
;
4659 tree_purge_dead_eh_edges (basic_block bb
)
4661 bool changed
= false;
4663 tree stmt
= last_stmt (bb
);
4665 if (stmt
&& tree_can_throw_internal (stmt
))
4668 for (e
= bb
->succ
; e
; e
= next
)
4670 next
= e
->succ_next
;
4671 if (e
->flags
& EDGE_EH
)
4673 ssa_remove_edge (e
);
4682 tree_purge_all_dead_eh_edges (bitmap blocks
)
4684 bool changed
= false;
4687 EXECUTE_IF_SET_IN_BITMAP (blocks
, 0, i
,
4688 { changed
|= tree_purge_dead_eh_edges (BASIC_BLOCK (i
)); });
4693 struct cfg_hooks tree_cfg_hooks
= {
4695 tree_verify_flow_info
,
4696 tree_dump_bb
, /* dump_bb */
4697 create_bb
, /* create_basic_block */
4698 tree_redirect_edge_and_branch
,/* redirect_edge_and_branch */
4699 tree_redirect_edge_and_branch_force
,/* redirect_edge_and_branch_force */
4700 remove_bb
, /* delete_basic_block */
4701 tree_split_block
, /* split_block */
4702 tree_move_block_after
, /* move_block_after */
4703 tree_can_merge_blocks_p
, /* can_merge_blocks_p */
4704 tree_merge_blocks
, /* merge_blocks */
4705 tree_predict_edge
, /* predict_edge */
4706 tree_predicted_by_p
, /* predicted_by_p */
4707 tree_can_duplicate_bb_p
, /* can_duplicate_block_p */
4708 tree_duplicate_bb
, /* duplicate_block */
4709 tree_split_edge
, /* split_edge */
4710 tree_make_forwarder_block
, /* make_forward_block */
4711 NULL
, /* tidy_fallthru_edge */
4712 tree_block_ends_with_call_p
, /* block_ends_with_call_p */
4713 tree_block_ends_with_condjump_p
, /* block_ends_with_condjump_p */
4714 tree_flow_call_edges_add
/* flow_call_edges_add */
4718 /* Split all critical edges. */
4721 split_critical_edges (void)
4728 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
4729 if (EDGE_CRITICAL_P (e
) && !(e
->flags
& EDGE_ABNORMAL
))
4736 struct tree_opt_pass pass_split_crit_edges
=
4738 "crited", /* name */
4740 split_critical_edges
, /* execute */
4743 0, /* static_pass_number */
4744 TV_TREE_SPLIT_EDGES
, /* tv_id */
4745 PROP_cfg
, /* properties required */
4746 PROP_no_crit_edges
, /* properties_provided */
4747 0, /* properties_destroyed */
4748 0, /* todo_flags_start */
4749 TODO_dump_func
, /* todo_flags_finish */
4752 /* Emit return warnings. */
4755 execute_warn_function_return (void)
4757 #ifdef USE_MAPPED_LOCATION
4758 source_location location
;
4765 if (warn_missing_noreturn
4766 && !TREE_THIS_VOLATILE (cfun
->decl
)
4767 && EXIT_BLOCK_PTR
->pred
== NULL
4768 && !lang_hooks
.function
.missing_noreturn_ok_p (cfun
->decl
))
4769 warning ("%Jfunction might be possible candidate for attribute `noreturn'",
4772 /* If we have a path to EXIT, then we do return. */
4773 if (TREE_THIS_VOLATILE (cfun
->decl
)
4774 && EXIT_BLOCK_PTR
->pred
!= NULL
)
4776 #ifdef USE_MAPPED_LOCATION
4777 location
= UNKNOWN_LOCATION
;
4781 for (e
= EXIT_BLOCK_PTR
->pred
; e
; e
= e
->pred_next
)
4783 last
= last_stmt (e
->src
);
4784 if (TREE_CODE (last
) == RETURN_EXPR
4785 #ifdef USE_MAPPED_LOCATION
4786 && (location
= EXPR_LOCATION (last
)) != UNKNOWN_LOCATION
)
4788 && (locus
= EXPR_LOCUS (last
)) != NULL
)
4792 #ifdef USE_MAPPED_LOCATION
4793 if (location
== UNKNOWN_LOCATION
)
4794 location
= cfun
->function_end_locus
;
4795 warning ("%H`noreturn' function does return", &location
);
4798 locus
= &cfun
->function_end_locus
;
4799 warning ("%H`noreturn' function does return", locus
);
4803 /* If we see "return;" in some basic block, then we do reach the end
4804 without returning a value. */
4805 else if (warn_return_type
4806 && EXIT_BLOCK_PTR
->pred
!= NULL
4807 && !VOID_TYPE_P (TREE_TYPE (TREE_TYPE (cfun
->decl
))))
4809 for (e
= EXIT_BLOCK_PTR
->pred
; e
; e
= e
->pred_next
)
4811 tree last
= last_stmt (e
->src
);
4812 if (TREE_CODE (last
) == RETURN_EXPR
4813 && TREE_OPERAND (last
, 0) == NULL
)
4815 #ifdef USE_MAPPED_LOCATION
4816 location
= EXPR_LOCATION (last
);
4817 if (location
== UNKNOWN_LOCATION
)
4818 location
= cfun
->function_end_locus
;
4819 warning ("%Hcontrol reaches end of non-void function", &location
);
4821 locus
= EXPR_LOCUS (last
);
4823 locus
= &cfun
->function_end_locus
;
4824 warning ("%Hcontrol reaches end of non-void function", locus
);
4833 /* Given a basic block B which ends with a conditional and has
4834 precisely two successors, determine which of the edges is taken if
4835 the conditional is true and which is taken if the conditional is
4836 false. Set TRUE_EDGE and FALSE_EDGE appropriately. */
4839 extract_true_false_edges_from_block (basic_block b
,
4845 if (e
->flags
& EDGE_TRUE_VALUE
)
4848 *false_edge
= e
->succ_next
;
4853 *true_edge
= e
->succ_next
;
4857 struct tree_opt_pass pass_warn_function_return
=
4861 execute_warn_function_return
, /* execute */
4864 0, /* static_pass_number */
4866 PROP_cfg
, /* properties_required */
4867 0, /* properties_provided */
4868 0, /* properties_destroyed */
4869 0, /* todo_flags_start */
4870 0 /* todo_flags_finish */
4873 #include "gt-tree-cfg.h"