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);
77 static tree
tree_block_label (basic_block bb
);
80 static void make_edges (void);
81 static void make_ctrl_stmt_edges (basic_block
);
82 static void make_exit_edges (basic_block
);
83 static void make_cond_expr_edges (basic_block
);
84 static void make_switch_expr_edges (basic_block
);
85 static void make_goto_expr_edges (basic_block
);
86 static edge
tree_redirect_edge_and_branch (edge
, basic_block
);
87 static edge
tree_try_redirect_by_replacing_jump (edge
, basic_block
);
88 static void split_critical_edges (void);
90 /* Various helpers. */
91 static inline bool stmt_starts_bb_p (tree
, tree
);
92 static int tree_verify_flow_info (void);
93 static void tree_make_forwarder_block (edge
);
94 static bool thread_jumps (void);
95 static bool tree_forwarder_block_p (basic_block
);
96 static void bsi_commit_edge_inserts_1 (edge e
);
97 static void tree_cfg2vcg (FILE *);
99 /* Flowgraph optimization and cleanup. */
100 static void tree_merge_blocks (basic_block
, basic_block
);
101 static bool tree_can_merge_blocks_p (basic_block
, basic_block
);
102 static void remove_bb (basic_block
);
103 static void group_case_labels (void);
104 static void cleanup_dead_labels (void);
105 static bool cleanup_control_flow (void);
106 static bool cleanup_control_expr_graph (basic_block
, block_stmt_iterator
);
107 static edge
find_taken_edge_cond_expr (basic_block
, tree
);
108 static edge
find_taken_edge_switch_expr (basic_block
, tree
);
109 static tree
find_case_label_for_value (tree
, tree
);
110 static bool phi_alternatives_equal (basic_block
, edge
, edge
);
113 /*---------------------------------------------------------------------------
115 ---------------------------------------------------------------------------*/
117 /* Entry point to the CFG builder for trees. TP points to the list of
118 statements to be added to the flowgraph. */
121 build_tree_cfg (tree
*tp
)
123 /* Register specific tree functions. */
124 tree_register_cfg_hooks ();
126 /* Initialize rbi_pool. */
129 /* Initialize the basic block array. */
132 last_basic_block
= 0;
133 VARRAY_BB_INIT (basic_block_info
, initial_cfg_capacity
, "basic_block_info");
134 memset ((void *) &cfg_stats
, 0, sizeof (cfg_stats
));
136 /* Build a mapping of labels to their associated blocks. */
137 VARRAY_BB_INIT (label_to_block_map
, initial_cfg_capacity
,
138 "label to block map");
140 ENTRY_BLOCK_PTR
->next_bb
= EXIT_BLOCK_PTR
;
141 EXIT_BLOCK_PTR
->prev_bb
= ENTRY_BLOCK_PTR
;
143 found_computed_goto
= 0;
146 /* Computed gotos are hell to deal with, especially if there are
147 lots of them with a large number of destinations. So we factor
148 them to a common computed goto location before we build the
149 edge list. After we convert back to normal form, we will un-factor
150 the computed gotos since factoring introduces an unwanted jump. */
151 if (found_computed_goto
)
152 factor_computed_gotos ();
154 /* Make sure there is always at least one block, even if its empty. */
155 if (n_basic_blocks
== 0)
156 create_empty_bb (ENTRY_BLOCK_PTR
);
158 create_block_annotation (ENTRY_BLOCK_PTR
);
159 create_block_annotation (EXIT_BLOCK_PTR
);
161 /* Adjust the size of the array. */
162 VARRAY_GROW (basic_block_info
, n_basic_blocks
);
164 /* To speed up statement iterator walks, we first purge dead labels. */
165 cleanup_dead_labels ();
167 /* Group case nodes to reduce the number of edges.
168 We do this after cleaning up dead labels because otherwise we miss
169 a lot of obvious case merging opportunities. */
170 group_case_labels ();
172 /* Create the edges of the flowgraph. */
175 /* Debugging dumps. */
177 /* Write the flowgraph to a VCG file. */
179 int local_dump_flags
;
180 FILE *dump_file
= dump_begin (TDI_vcg
, &local_dump_flags
);
183 tree_cfg2vcg (dump_file
);
184 dump_end (TDI_vcg
, dump_file
);
188 /* Dump a textual representation of the flowgraph. */
190 dump_tree_cfg (dump_file
, dump_flags
);
194 execute_build_cfg (void)
196 build_tree_cfg (&DECL_SAVED_TREE (current_function_decl
));
199 struct tree_opt_pass pass_build_cfg
=
203 execute_build_cfg
, /* execute */
206 0, /* static_pass_number */
207 TV_TREE_CFG
, /* tv_id */
208 PROP_gimple_leh
, /* properties_required */
209 PROP_cfg
, /* properties_provided */
210 0, /* properties_destroyed */
211 0, /* todo_flags_start */
212 TODO_verify_stmts
/* todo_flags_finish */
215 /* Search the CFG for any computed gotos. If found, factor them to a
216 common computed goto site. Also record the location of that site so
217 that we can un-factor the gotos after we have converted back to
221 factor_computed_gotos (void)
224 tree factored_label_decl
= NULL
;
226 tree factored_computed_goto_label
= NULL
;
227 tree factored_computed_goto
= NULL
;
229 /* We know there are one or more computed gotos in this function.
230 Examine the last statement in each basic block to see if the block
231 ends with a computed goto. */
235 block_stmt_iterator bsi
= bsi_last (bb
);
240 last
= bsi_stmt (bsi
);
242 /* Ignore the computed goto we create when we factor the original
244 if (last
== factored_computed_goto
)
247 /* If the last statement is a computed goto, factor it. */
248 if (computed_goto_p (last
))
252 /* The first time we find a computed goto we need to create
253 the factored goto block and the variable each original
254 computed goto will use for their goto destination. */
255 if (! factored_computed_goto
)
257 basic_block new_bb
= create_empty_bb (bb
);
258 block_stmt_iterator new_bsi
= bsi_start (new_bb
);
260 /* Create the destination of the factored goto. Each original
261 computed goto will put its desired destination into this
262 variable and jump to the label we create immediately
264 var
= create_tmp_var (ptr_type_node
, "gotovar");
266 /* Build a label for the new block which will contain the
267 factored computed goto. */
268 factored_label_decl
= create_artificial_label ();
269 factored_computed_goto_label
270 = build1 (LABEL_EXPR
, void_type_node
, factored_label_decl
);
271 bsi_insert_after (&new_bsi
, factored_computed_goto_label
,
274 /* Build our new computed goto. */
275 factored_computed_goto
= build1 (GOTO_EXPR
, void_type_node
, var
);
276 bsi_insert_after (&new_bsi
, factored_computed_goto
,
280 /* Copy the original computed goto's destination into VAR. */
281 assignment
= build (MODIFY_EXPR
, ptr_type_node
,
282 var
, GOTO_DESTINATION (last
));
283 bsi_insert_before (&bsi
, assignment
, BSI_SAME_STMT
);
285 /* And re-vector the computed goto to the new destination. */
286 GOTO_DESTINATION (last
) = factored_label_decl
;
292 /* Create annotations for a single basic block. */
295 create_block_annotation (basic_block bb
)
297 /* Verify that the tree_annotations field is clear. */
298 if (bb
->tree_annotations
)
300 bb
->tree_annotations
= ggc_alloc_cleared (sizeof (struct bb_ann_d
));
304 /* Free the annotations for all the basic blocks. */
306 static void free_blocks_annotations (void)
308 clear_blocks_annotations ();
312 /* Clear the annotations for all the basic blocks. */
315 clear_blocks_annotations (void)
319 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
, NULL
, next_bb
)
320 bb
->tree_annotations
= NULL
;
324 /* Build a flowgraph for the statement_list STMT_LIST. */
327 make_blocks (tree stmt_list
)
329 tree_stmt_iterator i
= tsi_start (stmt_list
);
331 bool start_new_block
= true;
332 bool first_stmt_of_list
= true;
333 basic_block bb
= ENTRY_BLOCK_PTR
;
335 while (!tsi_end_p (i
))
342 /* If the statement starts a new basic block or if we have determined
343 in a previous pass that we need to create a new block for STMT, do
345 if (start_new_block
|| stmt_starts_bb_p (stmt
, prev_stmt
))
347 if (!first_stmt_of_list
)
348 stmt_list
= tsi_split_statement_list_before (&i
);
349 bb
= create_basic_block (stmt_list
, NULL
, bb
);
350 start_new_block
= false;
353 /* Now add STMT to BB and create the subgraphs for special statement
355 set_bb_for_stmt (stmt
, bb
);
357 if (computed_goto_p (stmt
))
358 found_computed_goto
= true;
360 /* If STMT is a basic block terminator, set START_NEW_BLOCK for the
362 if (stmt_ends_bb_p (stmt
))
363 start_new_block
= true;
366 first_stmt_of_list
= false;
371 /* Create and return a new empty basic block after bb AFTER. */
374 create_bb (void *h
, void *e
, basic_block after
)
381 /* Create and initialize a new basic block. */
383 memset (bb
, 0, sizeof (*bb
));
385 bb
->index
= last_basic_block
;
387 bb
->stmt_list
= h
? h
: alloc_stmt_list ();
389 /* Add the new block to the linked list of blocks. */
390 link_block (bb
, after
);
392 /* Grow the basic block array if needed. */
393 if ((size_t) last_basic_block
== VARRAY_SIZE (basic_block_info
))
395 size_t new_size
= last_basic_block
+ (last_basic_block
+ 3) / 4;
396 VARRAY_GROW (basic_block_info
, new_size
);
399 /* Add the newly created block to the array. */
400 BASIC_BLOCK (last_basic_block
) = bb
;
402 create_block_annotation (bb
);
407 initialize_bb_rbi (bb
);
412 /*---------------------------------------------------------------------------
414 ---------------------------------------------------------------------------*/
416 /* Join all the blocks in the flowgraph. */
424 /* Create an edge from entry to the first block with executable
426 make_edge (ENTRY_BLOCK_PTR
, BASIC_BLOCK (0), EDGE_FALLTHRU
);
428 /* Traverse basic block array placing edges. */
431 tree first
= first_stmt (bb
);
432 tree last
= last_stmt (bb
);
436 /* Edges for statements that always alter flow control. */
437 if (is_ctrl_stmt (last
))
438 make_ctrl_stmt_edges (bb
);
440 /* Edges for statements that sometimes alter flow control. */
441 if (is_ctrl_altering_stmt (last
))
442 make_exit_edges (bb
);
445 /* Finally, if no edges were created above, this is a regular
446 basic block that only needs a fallthru edge. */
447 if (bb
->succ
== NULL
)
448 make_edge (bb
, bb
->next_bb
, EDGE_FALLTHRU
);
451 /* If there is a fallthru edge to exit out of the last block, transform it
452 to a return statement. */
453 for (e
= EXIT_BLOCK_PTR
->prev_bb
->succ
; e
; e
= e
->succ_next
)
454 if (e
->flags
& EDGE_FALLTHRU
)
457 if (e
&& e
->dest
== EXIT_BLOCK_PTR
)
459 block_stmt_iterator bsi
;
460 basic_block ret_bb
= EXIT_BLOCK_PTR
->prev_bb
;
463 /* If E->SRC ends with a call that has an abnormal edge (for EH or
464 nonlocal goto), then we will need to split the edge to insert
465 an explicit return statement. */
466 if (e
!= ret_bb
->succ
|| e
->succ_next
)
468 ret_bb
= split_edge (e
);
471 e
->flags
&= ~EDGE_FALLTHRU
;
473 x
= build (RETURN_EXPR
, void_type_node
, NULL_TREE
);
474 bsi
= bsi_last (ret_bb
);
475 bsi_insert_after (&bsi
, x
, BSI_NEW_STMT
);
478 /* We do not care about fake edges, so remove any that the CFG
479 builder inserted for completeness. */
480 remove_fake_edges ();
482 /* Clean up the graph and warn for unreachable code. */
487 /* Create edges for control statement at basic block BB. */
490 make_ctrl_stmt_edges (basic_block bb
)
492 tree last
= last_stmt (bb
);
493 tree first
= first_stmt (bb
);
495 #if defined ENABLE_CHECKING
496 if (last
== NULL_TREE
)
500 if (TREE_CODE (first
) == LABEL_EXPR
501 && DECL_NONLOCAL (LABEL_EXPR_LABEL (first
)))
502 make_edge (ENTRY_BLOCK_PTR
, bb
, EDGE_ABNORMAL
);
504 switch (TREE_CODE (last
))
507 make_goto_expr_edges (bb
);
511 make_edge (bb
, EXIT_BLOCK_PTR
, 0);
515 make_cond_expr_edges (bb
);
519 make_switch_expr_edges (bb
);
523 make_eh_edges (last
);
524 /* Yet another NORETURN hack. */
525 if (bb
->succ
== NULL
)
526 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
535 /* Create exit edges for statements in block BB that alter the flow of
536 control. Statements that alter the control flow are 'goto', 'return'
537 and calls to non-returning functions. */
540 make_exit_edges (basic_block bb
)
542 tree last
= last_stmt (bb
);
544 if (last
== NULL_TREE
)
547 switch (TREE_CODE (last
))
550 /* If this function receives a nonlocal goto, then we need to
551 make edges from this call site to all the nonlocal goto
553 if (TREE_SIDE_EFFECTS (last
)
554 && current_function_has_nonlocal_label
)
555 make_goto_expr_edges (bb
);
557 /* If this statement has reachable exception handlers, then
558 create abnormal edges to them. */
559 make_eh_edges (last
);
561 /* Some calls are known not to return. For such calls we create
564 We really need to revamp how we build edges so that it's not
565 such a bloody pain to avoid creating edges for this case since
566 all we do is remove these edges when we're done building the
568 if (call_expr_flags (last
) & (ECF_NORETURN
| ECF_LONGJMP
))
570 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
574 /* Don't forget the fall-thru edge. */
575 make_edge (bb
, bb
->next_bb
, EDGE_FALLTHRU
);
579 /* A MODIFY_EXPR may have a CALL_EXPR on its RHS and the CALL_EXPR
580 may have an abnormal edge. Search the RHS for this case and
581 create any required edges. */
582 if (TREE_CODE (TREE_OPERAND (last
, 1)) == CALL_EXPR
583 && TREE_SIDE_EFFECTS (TREE_OPERAND (last
, 1))
584 && current_function_has_nonlocal_label
)
585 make_goto_expr_edges (bb
);
587 make_eh_edges (last
);
588 make_edge (bb
, bb
->next_bb
, EDGE_FALLTHRU
);
597 /* Create the edges for a COND_EXPR starting at block BB.
598 At this point, both clauses must contain only simple gotos. */
601 make_cond_expr_edges (basic_block bb
)
603 tree entry
= last_stmt (bb
);
604 basic_block then_bb
, else_bb
;
605 tree then_label
, else_label
;
607 #if defined ENABLE_CHECKING
608 if (entry
== NULL_TREE
|| TREE_CODE (entry
) != COND_EXPR
)
612 /* Entry basic blocks for each component. */
613 then_label
= GOTO_DESTINATION (COND_EXPR_THEN (entry
));
614 else_label
= GOTO_DESTINATION (COND_EXPR_ELSE (entry
));
615 then_bb
= label_to_block (then_label
);
616 else_bb
= label_to_block (else_label
);
618 make_edge (bb
, then_bb
, EDGE_TRUE_VALUE
);
619 make_edge (bb
, else_bb
, EDGE_FALSE_VALUE
);
623 /* Create the edges for a SWITCH_EXPR starting at block BB.
624 At this point, the switch body has been lowered and the
625 SWITCH_LABELS filled in, so this is in effect a multi-way branch. */
628 make_switch_expr_edges (basic_block bb
)
630 tree entry
= last_stmt (bb
);
634 vec
= SWITCH_LABELS (entry
);
635 n
= TREE_VEC_LENGTH (vec
);
637 for (i
= 0; i
< n
; ++i
)
639 tree lab
= CASE_LABEL (TREE_VEC_ELT (vec
, i
));
640 basic_block label_bb
= label_to_block (lab
);
641 make_edge (bb
, label_bb
, 0);
646 /* Return the basic block holding label DEST. */
649 label_to_block (tree dest
)
651 return VARRAY_BB (label_to_block_map
, LABEL_DECL_UID (dest
));
655 /* Create edges for a goto statement at block BB. */
658 make_goto_expr_edges (basic_block bb
)
661 basic_block target_bb
;
663 block_stmt_iterator last
= bsi_last (bb
);
665 goto_t
= bsi_stmt (last
);
667 /* If the last statement is not a GOTO (i.e., it is a RETURN_EXPR,
668 CALL_EXPR or MODIFY_EXPR), then the edge is an abnormal edge resulting
669 from a nonlocal goto. */
670 if (TREE_CODE (goto_t
) != GOTO_EXPR
)
672 dest
= error_mark_node
;
677 dest
= GOTO_DESTINATION (goto_t
);
680 /* A GOTO to a local label creates normal edges. */
681 if (simple_goto_p (goto_t
))
683 make_edge (bb
, label_to_block (dest
), EDGE_FALLTHRU
);
688 /* Nothing more to do for nonlocal gotos. */
689 if (TREE_CODE (dest
) == LABEL_DECL
)
692 /* Computed gotos remain. */
695 /* Look for the block starting with the destination label. In the
696 case of a computed goto, make an edge to any label block we find
698 FOR_EACH_BB (target_bb
)
700 block_stmt_iterator bsi
;
702 for (bsi
= bsi_start (target_bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
704 tree target
= bsi_stmt (bsi
);
706 if (TREE_CODE (target
) != LABEL_EXPR
)
710 /* Computed GOTOs. Make an edge to every label block that has
711 been marked as a potential target for a computed goto. */
712 (FORCED_LABEL (LABEL_EXPR_LABEL (target
)) && for_call
== 0)
713 /* Nonlocal GOTO target. Make an edge to every label block
714 that has been marked as a potential target for a nonlocal
716 || (DECL_NONLOCAL (LABEL_EXPR_LABEL (target
)) && for_call
== 1))
718 make_edge (bb
, target_bb
, EDGE_ABNORMAL
);
724 /* Degenerate case of computed goto with no labels. */
725 if (!for_call
&& !bb
->succ
)
726 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
730 /*---------------------------------------------------------------------------
732 ---------------------------------------------------------------------------*/
734 /* Remove unreachable blocks and other miscellaneous clean up work. */
737 cleanup_tree_cfg (void)
739 bool something_changed
= true;
741 timevar_push (TV_TREE_CLEANUP_CFG
);
743 /* These three transformations can cascade, so we iterate on them until
745 while (something_changed
)
747 something_changed
= cleanup_control_flow ();
748 something_changed
|= thread_jumps ();
749 something_changed
|= delete_unreachable_blocks ();
752 /* Merging the blocks creates no new opportunities for the other
753 optimizations, so do it here. */
758 #ifdef ENABLE_CHECKING
761 timevar_pop (TV_TREE_CLEANUP_CFG
);
765 /* Cleanup useless labels from the flow graph. */
768 cleanup_dead_labels (void)
771 tree
*label_for_bb
= xcalloc (last_basic_block
, sizeof (tree
));
773 /* Find a suitable label for each block. We use the first user-defined
774 label is there is one, or otherwise just the first label we see. */
777 block_stmt_iterator i
;
779 for (i
= bsi_start (bb
); !bsi_end_p (i
); bsi_next (&i
))
781 tree label
, stmt
= bsi_stmt (i
);
783 if (TREE_CODE (stmt
) != LABEL_EXPR
)
786 label
= LABEL_EXPR_LABEL (stmt
);
788 /* If we have not yet seen a label for the current block,
789 remember this one and see if there are more labels. */
790 if (! label_for_bb
[bb
->index
])
792 label_for_bb
[bb
->index
] = label
;
796 /* If we did see a label for the current block already, but it
797 is an artificially created label, replace it if the current
798 label is a user defined label. */
799 if (! DECL_ARTIFICIAL (label
)
800 && DECL_ARTIFICIAL (label_for_bb
[bb
->index
]))
802 label_for_bb
[bb
->index
] = label
;
808 /* Now redirect all jumps/branches to the selected label for each block. */
811 tree stmt
= last_stmt (bb
);
815 switch (TREE_CODE (stmt
))
819 tree true_branch
, false_branch
;
820 basic_block true_bb
, false_bb
;
822 true_branch
= COND_EXPR_THEN (stmt
);
823 false_branch
= COND_EXPR_ELSE (stmt
);
824 true_bb
= label_to_block (GOTO_DESTINATION (true_branch
));
825 false_bb
= label_to_block (GOTO_DESTINATION (false_branch
));
827 GOTO_DESTINATION (true_branch
) = label_for_bb
[true_bb
->index
];
828 GOTO_DESTINATION (false_branch
) = label_for_bb
[false_bb
->index
];
836 tree vec
= SWITCH_LABELS (stmt
);
837 size_t n
= TREE_VEC_LENGTH (vec
);
839 /* Replace all destination labels. */
840 for (i
= 0; i
< n
; ++i
)
842 tree label
= CASE_LABEL (TREE_VEC_ELT (vec
, i
));
844 CASE_LABEL (TREE_VEC_ELT (vec
, i
)) =
845 label_for_bb
[label_to_block (label
)->index
];
851 /* We have to handle GOTO_EXPRs until they're removed, and we don't
852 remove them until after we've created the CFG edges. */
855 tree label
= GOTO_DESTINATION (stmt
);
856 if (! computed_goto_p (stmt
))
857 GOTO_DESTINATION (stmt
) =
858 label_for_bb
[label_to_block (label
)->index
];
867 /* Finally, purge dead labels. All user-defined labels and labels that
868 can be the target of non-local gotos are preserved. */
871 block_stmt_iterator i
;
872 tree label_for_this_bb
= label_for_bb
[bb
->index
];
874 if (! label_for_this_bb
)
877 for (i
= bsi_start (bb
); !bsi_end_p (i
); )
879 tree label
, stmt
= bsi_stmt (i
);
881 if (TREE_CODE (stmt
) != LABEL_EXPR
)
884 label
= LABEL_EXPR_LABEL (stmt
);
886 if (label
== label_for_this_bb
887 || ! DECL_ARTIFICIAL (label
)
888 || DECL_NONLOCAL (label
))
898 /* Look for blocks ending in a multiway branch (a SWITCH_EXPR in GIMPLE),
899 and scan the sorted vector of cases. Combine the ones jumping to the
901 Eg. three separate entries 1: 2: 3: become one entry 1..3: */
904 group_case_labels (void)
910 tree stmt
= last_stmt (bb
);
911 if (stmt
&& TREE_CODE (stmt
) == SWITCH_EXPR
)
913 tree labels
= SWITCH_LABELS (stmt
);
914 int old_size
= TREE_VEC_LENGTH (labels
);
915 int i
, j
, new_size
= old_size
;
917 /* Look for possible opportunities to merge cases.
918 Ignore the last element of the label vector because it
919 must be the default case. */
921 while (i
< old_size
- 2)
923 tree base_case
, base_label
, base_high
, type
;
924 base_case
= TREE_VEC_ELT (labels
, i
);
929 type
= TREE_TYPE (CASE_LOW (base_case
));
930 base_label
= CASE_LABEL (base_case
);
931 base_high
= CASE_HIGH (base_case
) ?
932 CASE_HIGH (base_case
) : CASE_LOW (base_case
);
934 /* Try to merge case labels. Break out when we reach the end
935 of the label vector or when we cannot merge the next case
936 label with the current one. */
937 while (i
< old_size
- 2)
939 tree merge_case
= TREE_VEC_ELT (labels
, ++i
);
940 tree merge_label
= CASE_LABEL (merge_case
);
941 tree t
= int_const_binop (PLUS_EXPR
, base_high
,
942 integer_one_node
, 1);
944 /* Merge the cases if they jump to the same place,
945 and their ranges are consecutive. */
946 if (merge_label
== base_label
947 && tree_int_cst_equal (CASE_LOW (merge_case
), t
))
949 base_high
= CASE_HIGH (merge_case
) ?
950 CASE_HIGH (merge_case
) : CASE_LOW (merge_case
);
951 CASE_HIGH (base_case
) = base_high
;
952 TREE_VEC_ELT (labels
, i
) = NULL_TREE
;
960 /* Compress the case labels in the label vector, and adjust the
961 length of the vector. */
962 for (i
= 0, j
= 0; i
< new_size
; i
++)
964 while (! TREE_VEC_ELT (labels
, j
))
966 TREE_VEC_ELT (labels
, i
) = TREE_VEC_ELT (labels
, j
++);
968 TREE_VEC_LENGTH (labels
) = new_size
;
973 /* Checks whether we can merge block B into block A. */
976 tree_can_merge_blocks_p (basic_block a
, basic_block b
)
979 block_stmt_iterator bsi
;
982 || a
->succ
->succ_next
)
985 if (a
->succ
->flags
& EDGE_ABNORMAL
)
988 if (a
->succ
->dest
!= b
)
991 if (b
== EXIT_BLOCK_PTR
)
994 if (b
->pred
->pred_next
)
997 /* If A ends by a statement causing exceptions or something similar, we
998 cannot merge the blocks. */
999 stmt
= last_stmt (a
);
1000 if (stmt
&& stmt_ends_bb_p (stmt
))
1003 /* Do not allow a block with only a non-local label to be merged. */
1004 if (stmt
&& TREE_CODE (stmt
) == LABEL_EXPR
1005 && DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt
)))
1008 /* There may be no phi nodes at the start of b. Most of these degenerate
1009 phi nodes should be cleaned up by kill_redundant_phi_nodes. */
1013 /* Do not remove user labels. */
1014 for (bsi
= bsi_start (b
); !bsi_end_p (bsi
); bsi_next (&bsi
))
1016 stmt
= bsi_stmt (bsi
);
1017 if (TREE_CODE (stmt
) != LABEL_EXPR
)
1019 if (!DECL_ARTIFICIAL (LABEL_EXPR_LABEL (stmt
)))
1027 /* Merge block B into block A. */
1030 tree_merge_blocks (basic_block a
, basic_block b
)
1032 block_stmt_iterator bsi
;
1033 tree_stmt_iterator last
;
1036 fprintf (dump_file
, "Merging blocks %d and %d\n", a
->index
, b
->index
);
1038 /* Ensure that B follows A. */
1039 move_block_after (b
, a
);
1041 if (!(a
->succ
->flags
& EDGE_FALLTHRU
))
1045 && stmt_ends_bb_p (last_stmt (a
)))
1048 /* Remove labels from B and set bb_for_stmt to A for other statements. */
1049 for (bsi
= bsi_start (b
); !bsi_end_p (bsi
);)
1051 if (TREE_CODE (bsi_stmt (bsi
)) == LABEL_EXPR
)
1055 set_bb_for_stmt (bsi_stmt (bsi
), a
);
1060 /* Merge the chains. */
1061 last
= tsi_last (a
->stmt_list
);
1062 tsi_link_after (&last
, b
->stmt_list
, TSI_NEW_STMT
);
1063 b
->stmt_list
= NULL
;
1067 /* Walk the function tree removing unnecessary statements.
1069 * Empty statement nodes are removed
1071 * Unnecessary TRY_FINALLY and TRY_CATCH blocks are removed
1073 * Unnecessary COND_EXPRs are removed
1075 * Some unnecessary BIND_EXPRs are removed
1077 Clearly more work could be done. The trick is doing the analysis
1078 and removal fast enough to be a net improvement in compile times.
1080 Note that when we remove a control structure such as a COND_EXPR
1081 BIND_EXPR, or TRY block, we will need to repeat this optimization pass
1082 to ensure we eliminate all the useless code. */
1093 static void remove_useless_stmts_1 (tree
*, struct rus_data
*);
1096 remove_useless_stmts_warn_notreached (tree stmt
)
1098 if (EXPR_LOCUS (stmt
))
1100 warning ("%Hwill never be executed", EXPR_LOCUS (stmt
));
1104 switch (TREE_CODE (stmt
))
1106 case STATEMENT_LIST
:
1108 tree_stmt_iterator i
;
1109 for (i
= tsi_start (stmt
); !tsi_end_p (i
); tsi_next (&i
))
1110 if (remove_useless_stmts_warn_notreached (tsi_stmt (i
)))
1116 if (remove_useless_stmts_warn_notreached (COND_EXPR_COND (stmt
)))
1118 if (remove_useless_stmts_warn_notreached (COND_EXPR_THEN (stmt
)))
1120 if (remove_useless_stmts_warn_notreached (COND_EXPR_ELSE (stmt
)))
1124 case TRY_FINALLY_EXPR
:
1125 case TRY_CATCH_EXPR
:
1126 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt
, 0)))
1128 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt
, 1)))
1133 return remove_useless_stmts_warn_notreached (CATCH_BODY (stmt
));
1134 case EH_FILTER_EXPR
:
1135 return remove_useless_stmts_warn_notreached (EH_FILTER_FAILURE (stmt
));
1137 return remove_useless_stmts_warn_notreached (BIND_EXPR_BLOCK (stmt
));
1140 /* Not a live container. */
1148 remove_useless_stmts_cond (tree
*stmt_p
, struct rus_data
*data
)
1150 tree then_clause
, else_clause
, cond
;
1151 bool save_has_label
, then_has_label
, else_has_label
;
1153 save_has_label
= data
->has_label
;
1154 data
->has_label
= false;
1155 data
->last_goto
= NULL
;
1157 remove_useless_stmts_1 (&COND_EXPR_THEN (*stmt_p
), data
);
1159 then_has_label
= data
->has_label
;
1160 data
->has_label
= false;
1161 data
->last_goto
= NULL
;
1163 remove_useless_stmts_1 (&COND_EXPR_ELSE (*stmt_p
), data
);
1165 else_has_label
= data
->has_label
;
1166 data
->has_label
= save_has_label
| then_has_label
| else_has_label
;
1169 then_clause
= COND_EXPR_THEN (*stmt_p
);
1170 else_clause
= COND_EXPR_ELSE (*stmt_p
);
1171 cond
= COND_EXPR_COND (*stmt_p
);
1173 /* If neither arm does anything at all, we can remove the whole IF. */
1174 if (!TREE_SIDE_EFFECTS (then_clause
) && !TREE_SIDE_EFFECTS (else_clause
))
1176 *stmt_p
= build_empty_stmt ();
1177 data
->repeat
= true;
1180 /* If there are no reachable statements in an arm, then we can
1181 zap the entire conditional. */
1182 else if (integer_nonzerop (cond
) && !else_has_label
)
1184 if (warn_notreached
)
1185 remove_useless_stmts_warn_notreached (else_clause
);
1186 *stmt_p
= then_clause
;
1187 data
->repeat
= true;
1189 else if (integer_zerop (cond
) && !then_has_label
)
1191 if (warn_notreached
)
1192 remove_useless_stmts_warn_notreached (then_clause
);
1193 *stmt_p
= else_clause
;
1194 data
->repeat
= true;
1197 /* Check a couple of simple things on then/else with single stmts. */
1200 tree then_stmt
= expr_only (then_clause
);
1201 tree else_stmt
= expr_only (else_clause
);
1203 /* Notice branches to a common destination. */
1204 if (then_stmt
&& else_stmt
1205 && TREE_CODE (then_stmt
) == GOTO_EXPR
1206 && TREE_CODE (else_stmt
) == GOTO_EXPR
1207 && (GOTO_DESTINATION (then_stmt
) == GOTO_DESTINATION (else_stmt
)))
1209 *stmt_p
= then_stmt
;
1210 data
->repeat
= true;
1213 /* If the THEN/ELSE clause merely assigns a value to a variable or
1214 parameter which is already known to contain that value, then
1215 remove the useless THEN/ELSE clause. */
1216 else if (TREE_CODE (cond
) == VAR_DECL
|| TREE_CODE (cond
) == PARM_DECL
)
1219 && TREE_CODE (else_stmt
) == MODIFY_EXPR
1220 && TREE_OPERAND (else_stmt
, 0) == cond
1221 && integer_zerop (TREE_OPERAND (else_stmt
, 1)))
1222 COND_EXPR_ELSE (*stmt_p
) = alloc_stmt_list ();
1224 else if ((TREE_CODE (cond
) == EQ_EXPR
|| TREE_CODE (cond
) == NE_EXPR
)
1225 && (TREE_CODE (TREE_OPERAND (cond
, 0)) == VAR_DECL
1226 || TREE_CODE (TREE_OPERAND (cond
, 0)) == PARM_DECL
)
1227 && TREE_CONSTANT (TREE_OPERAND (cond
, 1)))
1229 tree stmt
= (TREE_CODE (cond
) == EQ_EXPR
1230 ? then_stmt
: else_stmt
);
1231 tree
*location
= (TREE_CODE (cond
) == EQ_EXPR
1232 ? &COND_EXPR_THEN (*stmt_p
)
1233 : &COND_EXPR_ELSE (*stmt_p
));
1236 && TREE_CODE (stmt
) == MODIFY_EXPR
1237 && TREE_OPERAND (stmt
, 0) == TREE_OPERAND (cond
, 0)
1238 && TREE_OPERAND (stmt
, 1) == TREE_OPERAND (cond
, 1))
1239 *location
= alloc_stmt_list ();
1243 /* Protect GOTOs in the arm of COND_EXPRs from being removed. They
1244 would be re-introduced during lowering. */
1245 data
->last_goto
= NULL
;
1250 remove_useless_stmts_tf (tree
*stmt_p
, struct rus_data
*data
)
1252 bool save_may_branch
, save_may_throw
;
1253 bool this_may_branch
, this_may_throw
;
1255 /* Collect may_branch and may_throw information for the body only. */
1256 save_may_branch
= data
->may_branch
;
1257 save_may_throw
= data
->may_throw
;
1258 data
->may_branch
= false;
1259 data
->may_throw
= false;
1260 data
->last_goto
= NULL
;
1262 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p
, 0), data
);
1264 this_may_branch
= data
->may_branch
;
1265 this_may_throw
= data
->may_throw
;
1266 data
->may_branch
|= save_may_branch
;
1267 data
->may_throw
|= save_may_throw
;
1268 data
->last_goto
= NULL
;
1270 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p
, 1), data
);
1272 /* If the body is empty, then we can emit the FINALLY block without
1273 the enclosing TRY_FINALLY_EXPR. */
1274 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p
, 0)))
1276 *stmt_p
= TREE_OPERAND (*stmt_p
, 1);
1277 data
->repeat
= true;
1280 /* If the handler is empty, then we can emit the TRY block without
1281 the enclosing TRY_FINALLY_EXPR. */
1282 else if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p
, 1)))
1284 *stmt_p
= TREE_OPERAND (*stmt_p
, 0);
1285 data
->repeat
= true;
1288 /* If the body neither throws, nor branches, then we can safely
1289 string the TRY and FINALLY blocks together. */
1290 else if (!this_may_branch
&& !this_may_throw
)
1292 tree stmt
= *stmt_p
;
1293 *stmt_p
= TREE_OPERAND (stmt
, 0);
1294 append_to_statement_list (TREE_OPERAND (stmt
, 1), stmt_p
);
1295 data
->repeat
= true;
1301 remove_useless_stmts_tc (tree
*stmt_p
, struct rus_data
*data
)
1303 bool save_may_throw
, this_may_throw
;
1304 tree_stmt_iterator i
;
1307 /* Collect may_throw information for the body only. */
1308 save_may_throw
= data
->may_throw
;
1309 data
->may_throw
= false;
1310 data
->last_goto
= NULL
;
1312 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p
, 0), data
);
1314 this_may_throw
= data
->may_throw
;
1315 data
->may_throw
= save_may_throw
;
1317 /* If the body cannot throw, then we can drop the entire TRY_CATCH_EXPR. */
1318 if (!this_may_throw
)
1320 if (warn_notreached
)
1321 remove_useless_stmts_warn_notreached (TREE_OPERAND (*stmt_p
, 1));
1322 *stmt_p
= TREE_OPERAND (*stmt_p
, 0);
1323 data
->repeat
= true;
1327 /* Process the catch clause specially. We may be able to tell that
1328 no exceptions propagate past this point. */
1330 this_may_throw
= true;
1331 i
= tsi_start (TREE_OPERAND (*stmt_p
, 1));
1332 stmt
= tsi_stmt (i
);
1333 data
->last_goto
= NULL
;
1335 switch (TREE_CODE (stmt
))
1338 for (; !tsi_end_p (i
); tsi_next (&i
))
1340 stmt
= tsi_stmt (i
);
1341 /* If we catch all exceptions, then the body does not
1342 propagate exceptions past this point. */
1343 if (CATCH_TYPES (stmt
) == NULL
)
1344 this_may_throw
= false;
1345 data
->last_goto
= NULL
;
1346 remove_useless_stmts_1 (&CATCH_BODY (stmt
), data
);
1350 case EH_FILTER_EXPR
:
1351 if (EH_FILTER_MUST_NOT_THROW (stmt
))
1352 this_may_throw
= false;
1353 else if (EH_FILTER_TYPES (stmt
) == NULL
)
1354 this_may_throw
= false;
1355 remove_useless_stmts_1 (&EH_FILTER_FAILURE (stmt
), data
);
1359 /* Otherwise this is a cleanup. */
1360 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p
, 1), data
);
1362 /* If the cleanup is empty, then we can emit the TRY block without
1363 the enclosing TRY_CATCH_EXPR. */
1364 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p
, 1)))
1366 *stmt_p
= TREE_OPERAND (*stmt_p
, 0);
1367 data
->repeat
= true;
1371 data
->may_throw
|= this_may_throw
;
1376 remove_useless_stmts_bind (tree
*stmt_p
, struct rus_data
*data
)
1380 /* First remove anything underneath the BIND_EXPR. */
1381 remove_useless_stmts_1 (&BIND_EXPR_BODY (*stmt_p
), data
);
1383 /* If the BIND_EXPR has no variables, then we can pull everything
1384 up one level and remove the BIND_EXPR, unless this is the toplevel
1385 BIND_EXPR for the current function or an inlined function.
1387 When this situation occurs we will want to apply this
1388 optimization again. */
1389 block
= BIND_EXPR_BLOCK (*stmt_p
);
1390 if (BIND_EXPR_VARS (*stmt_p
) == NULL_TREE
1391 && *stmt_p
!= DECL_SAVED_TREE (current_function_decl
)
1393 || ! BLOCK_ABSTRACT_ORIGIN (block
)
1394 || (TREE_CODE (BLOCK_ABSTRACT_ORIGIN (block
))
1397 *stmt_p
= BIND_EXPR_BODY (*stmt_p
);
1398 data
->repeat
= true;
1404 remove_useless_stmts_goto (tree
*stmt_p
, struct rus_data
*data
)
1406 tree dest
= GOTO_DESTINATION (*stmt_p
);
1408 data
->may_branch
= true;
1409 data
->last_goto
= NULL
;
1411 /* Record the last goto expr, so that we can delete it if unnecessary. */
1412 if (TREE_CODE (dest
) == LABEL_DECL
)
1413 data
->last_goto
= stmt_p
;
1418 remove_useless_stmts_label (tree
*stmt_p
, struct rus_data
*data
)
1420 tree label
= LABEL_EXPR_LABEL (*stmt_p
);
1422 data
->has_label
= true;
1424 /* We do want to jump across non-local label receiver code. */
1425 if (DECL_NONLOCAL (label
))
1426 data
->last_goto
= NULL
;
1428 else if (data
->last_goto
&& GOTO_DESTINATION (*data
->last_goto
) == label
)
1430 *data
->last_goto
= build_empty_stmt ();
1431 data
->repeat
= true;
1434 /* ??? Add something here to delete unused labels. */
1438 /* If the function is "const" or "pure", then clear TREE_SIDE_EFFECTS on its
1439 decl. This allows us to eliminate redundant or useless
1440 calls to "const" functions.
1442 Gimplifier already does the same operation, but we may notice functions
1443 being const and pure once their calls has been gimplified, so we need
1444 to update the flag. */
1447 update_call_expr_flags (tree call
)
1449 tree decl
= get_callee_fndecl (call
);
1452 if (call_expr_flags (call
) & (ECF_CONST
| ECF_PURE
))
1453 TREE_SIDE_EFFECTS (call
) = 0;
1454 if (TREE_NOTHROW (decl
))
1455 TREE_NOTHROW (call
) = 1;
1459 /* T is CALL_EXPR. Set current_function_calls_* flags. */
1462 notice_special_calls (tree t
)
1464 int flags
= call_expr_flags (t
);
1466 if (flags
& ECF_MAY_BE_ALLOCA
)
1467 current_function_calls_alloca
= true;
1468 if (flags
& ECF_RETURNS_TWICE
)
1469 current_function_calls_setjmp
= true;
1473 /* Clear flags set by notice_special_calls. Used by dead code removal
1474 to update the flags. */
1477 clear_special_calls (void)
1479 current_function_calls_alloca
= false;
1480 current_function_calls_setjmp
= false;
1485 remove_useless_stmts_1 (tree
*tp
, struct rus_data
*data
)
1489 switch (TREE_CODE (t
))
1492 remove_useless_stmts_cond (tp
, data
);
1495 case TRY_FINALLY_EXPR
:
1496 remove_useless_stmts_tf (tp
, data
);
1499 case TRY_CATCH_EXPR
:
1500 remove_useless_stmts_tc (tp
, data
);
1504 remove_useless_stmts_bind (tp
, data
);
1508 remove_useless_stmts_goto (tp
, data
);
1512 remove_useless_stmts_label (tp
, data
);
1517 data
->last_goto
= NULL
;
1518 data
->may_branch
= true;
1523 data
->last_goto
= NULL
;
1524 notice_special_calls (t
);
1525 update_call_expr_flags (t
);
1526 if (tree_could_throw_p (t
))
1527 data
->may_throw
= true;
1531 data
->last_goto
= NULL
;
1533 if (TREE_CODE (TREE_OPERAND (t
, 1)) == CALL_EXPR
)
1535 update_call_expr_flags (TREE_OPERAND (t
, 1));
1536 notice_special_calls (TREE_OPERAND (t
, 1));
1538 if (tree_could_throw_p (t
))
1539 data
->may_throw
= true;
1542 case STATEMENT_LIST
:
1544 tree_stmt_iterator i
= tsi_start (t
);
1545 while (!tsi_end_p (i
))
1548 if (IS_EMPTY_STMT (t
))
1554 remove_useless_stmts_1 (tsi_stmt_ptr (i
), data
);
1557 if (TREE_CODE (t
) == STATEMENT_LIST
)
1559 tsi_link_before (&i
, t
, TSI_SAME_STMT
);
1569 data
->last_goto
= NULL
;
1573 data
->last_goto
= NULL
;
1579 remove_useless_stmts (void)
1581 struct rus_data data
;
1583 clear_special_calls ();
1587 memset (&data
, 0, sizeof (data
));
1588 remove_useless_stmts_1 (&DECL_SAVED_TREE (current_function_decl
), &data
);
1590 while (data
.repeat
);
1594 struct tree_opt_pass pass_remove_useless_stmts
=
1596 "useless", /* name */
1598 remove_useless_stmts
, /* execute */
1601 0, /* static_pass_number */
1603 PROP_gimple_any
, /* properties_required */
1604 0, /* properties_provided */
1605 0, /* properties_destroyed */
1606 0, /* todo_flags_start */
1607 TODO_dump_func
/* todo_flags_finish */
1611 /* Remove obviously useless statements in basic block BB. */
1614 cfg_remove_useless_stmts_bb (basic_block bb
)
1616 block_stmt_iterator bsi
;
1617 tree stmt
= NULL_TREE
;
1618 tree cond
, var
= NULL_TREE
, val
= NULL_TREE
;
1619 struct var_ann_d
*ann
;
1621 /* Check whether we come here from a condition, and if so, get the
1624 || bb
->pred
->pred_next
1625 || !(bb
->pred
->flags
& (EDGE_TRUE_VALUE
| EDGE_FALSE_VALUE
)))
1628 cond
= COND_EXPR_COND (last_stmt (bb
->pred
->src
));
1630 if (TREE_CODE (cond
) == VAR_DECL
|| TREE_CODE (cond
) == PARM_DECL
)
1633 val
= (bb
->pred
->flags
& EDGE_FALSE_VALUE
1634 ? boolean_false_node
: boolean_true_node
);
1636 else if (TREE_CODE (cond
) == TRUTH_NOT_EXPR
1637 && (TREE_CODE (TREE_OPERAND (cond
, 0)) == VAR_DECL
1638 || TREE_CODE (TREE_OPERAND (cond
, 0)) == PARM_DECL
))
1640 var
= TREE_OPERAND (cond
, 0);
1641 val
= (bb
->pred
->flags
& EDGE_FALSE_VALUE
1642 ? boolean_true_node
: boolean_false_node
);
1646 if (bb
->pred
->flags
& EDGE_FALSE_VALUE
)
1647 cond
= invert_truthvalue (cond
);
1648 if (TREE_CODE (cond
) == EQ_EXPR
1649 && (TREE_CODE (TREE_OPERAND (cond
, 0)) == VAR_DECL
1650 || TREE_CODE (TREE_OPERAND (cond
, 0)) == PARM_DECL
)
1651 && (TREE_CODE (TREE_OPERAND (cond
, 1)) == VAR_DECL
1652 || TREE_CODE (TREE_OPERAND (cond
, 1)) == PARM_DECL
1653 || TREE_CONSTANT (TREE_OPERAND (cond
, 1))))
1655 var
= TREE_OPERAND (cond
, 0);
1656 val
= TREE_OPERAND (cond
, 1);
1662 /* Only work for normal local variables. */
1663 ann
= var_ann (var
);
1666 || TREE_ADDRESSABLE (var
))
1669 if (! TREE_CONSTANT (val
))
1671 ann
= var_ann (val
);
1674 || TREE_ADDRESSABLE (val
))
1678 /* Ignore floating point variables, since comparison behaves weird for
1680 if (FLOAT_TYPE_P (TREE_TYPE (var
)))
1683 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
);)
1685 stmt
= bsi_stmt (bsi
);
1687 /* If the THEN/ELSE clause merely assigns a value to a variable/parameter
1688 which is already known to contain that value, then remove the useless
1689 THEN/ELSE clause. */
1690 if (TREE_CODE (stmt
) == MODIFY_EXPR
1691 && TREE_OPERAND (stmt
, 0) == var
1692 && operand_equal_p (val
, TREE_OPERAND (stmt
, 1), 0))
1698 /* Invalidate the var if we encounter something that could modify it. */
1699 if (TREE_CODE (stmt
) == ASM_EXPR
1700 || TREE_CODE (stmt
) == VA_ARG_EXPR
1701 || (TREE_CODE (stmt
) == MODIFY_EXPR
1702 && (TREE_OPERAND (stmt
, 0) == var
1703 || TREE_OPERAND (stmt
, 0) == val
1704 || TREE_CODE (TREE_OPERAND (stmt
, 1)) == VA_ARG_EXPR
)))
1712 /* A CFG-aware version of remove_useless_stmts. */
1715 cfg_remove_useless_stmts (void)
1719 #ifdef ENABLE_CHECKING
1720 verify_flow_info ();
1725 cfg_remove_useless_stmts_bb (bb
);
1730 /* Remove PHI nodes associated with basic block BB and all edges out of BB. */
1733 remove_phi_nodes_and_edges_for_unreachable_block (basic_block bb
)
1737 /* Since this block is no longer reachable, we can just delete all
1738 of its PHI nodes. */
1739 phi
= phi_nodes (bb
);
1742 tree next
= TREE_CHAIN (phi
);
1743 remove_phi_node (phi
, NULL_TREE
, bb
);
1747 /* Remove edges to BB's successors. */
1748 while (bb
->succ
!= NULL
)
1749 ssa_remove_edge (bb
->succ
);
1753 /* Remove statements of basic block BB. */
1756 remove_bb (basic_block bb
)
1758 block_stmt_iterator i
;
1759 location_t
*loc
= NULL
;
1763 fprintf (dump_file
, "Removing basic block %d\n", bb
->index
);
1764 if (dump_flags
& TDF_DETAILS
)
1766 dump_bb (bb
, dump_file
, 0);
1767 fprintf (dump_file
, "\n");
1771 /* Remove all the instructions in the block. */
1772 for (i
= bsi_start (bb
); !bsi_end_p (i
); bsi_remove (&i
))
1774 tree stmt
= bsi_stmt (i
);
1776 set_bb_for_stmt (stmt
, NULL
);
1778 /* Don't warn for removed gotos. Gotos are often removed due to
1779 jump threading, thus resulting in bogus warnings. Not great,
1780 since this way we lose warnings for gotos in the original
1781 program that are indeed unreachable. */
1782 if (TREE_CODE (stmt
) != GOTO_EXPR
&& EXPR_LOCUS (stmt
) && !loc
)
1783 loc
= EXPR_LOCUS (stmt
);
1786 /* If requested, give a warning that the first statement in the
1787 block is unreachable. We walk statements backwards in the
1788 loop above, so the last statement we process is the first statement
1790 if (warn_notreached
&& loc
)
1791 warning ("%Hwill never be executed", loc
);
1793 remove_phi_nodes_and_edges_for_unreachable_block (bb
);
1797 /* Examine BB to determine if it is a forwarding block (a block which only
1798 transfers control to a new destination). If BB is a forwarding block,
1799 then return the edge leading to the ultimate destination. */
1802 tree_block_forwards_to (basic_block bb
)
1804 block_stmt_iterator bsi
;
1805 bb_ann_t ann
= bb_ann (bb
);
1808 /* If this block is not forwardable, then avoid useless work. */
1809 if (! ann
->forwardable
)
1812 /* Set this block to not be forwardable. This prevents infinite loops since
1813 any block currently under examination is considered non-forwardable. */
1814 ann
->forwardable
= 0;
1816 /* No forwarding is possible if this block is a special block (ENTRY/EXIT),
1817 this block has more than one successor, this block's single successor is
1818 reached via an abnormal edge, this block has phi nodes, or this block's
1819 single successor has phi nodes. */
1820 if (bb
== EXIT_BLOCK_PTR
1821 || bb
== ENTRY_BLOCK_PTR
1823 || bb
->succ
->succ_next
1824 || bb
->succ
->dest
== EXIT_BLOCK_PTR
1825 || (bb
->succ
->flags
& EDGE_ABNORMAL
) != 0
1827 || phi_nodes (bb
->succ
->dest
))
1830 /* Walk past any labels at the start of this block. */
1831 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
1833 stmt
= bsi_stmt (bsi
);
1834 if (TREE_CODE (stmt
) != LABEL_EXPR
)
1838 /* If we reached the end of this block we may be able to optimize this
1840 if (bsi_end_p (bsi
))
1844 /* Recursive call to pick up chains of forwarding blocks. */
1845 dest
= tree_block_forwards_to (bb
->succ
->dest
);
1847 /* If none found, we forward to bb->succ at minimum. */
1851 ann
->forwardable
= 1;
1855 /* No forwarding possible. */
1860 /* Try to remove superfluous control structures. */
1863 cleanup_control_flow (void)
1866 block_stmt_iterator bsi
;
1867 bool retval
= false;
1872 bsi
= bsi_last (bb
);
1874 if (bsi_end_p (bsi
))
1877 stmt
= bsi_stmt (bsi
);
1878 if (TREE_CODE (stmt
) == COND_EXPR
1879 || TREE_CODE (stmt
) == SWITCH_EXPR
)
1880 retval
|= cleanup_control_expr_graph (bb
, bsi
);
1886 /* Disconnect an unreachable block in the control expression starting
1890 cleanup_control_expr_graph (basic_block bb
, block_stmt_iterator bsi
)
1893 bool retval
= false;
1894 tree expr
= bsi_stmt (bsi
), val
;
1896 if (bb
->succ
->succ_next
)
1900 switch (TREE_CODE (expr
))
1903 val
= COND_EXPR_COND (expr
);
1907 val
= SWITCH_COND (expr
);
1908 if (TREE_CODE (val
) != INTEGER_CST
)
1916 taken_edge
= find_taken_edge (bb
, val
);
1920 /* Remove all the edges except the one that is always executed. */
1921 for (e
= bb
->succ
; e
; e
= next
)
1923 next
= e
->succ_next
;
1924 if (e
!= taken_edge
)
1926 taken_edge
->probability
+= e
->probability
;
1927 taken_edge
->count
+= e
->count
;
1928 ssa_remove_edge (e
);
1932 if (taken_edge
->probability
> REG_BR_PROB_BASE
)
1933 taken_edge
->probability
= REG_BR_PROB_BASE
;
1936 taken_edge
= bb
->succ
;
1939 taken_edge
->flags
= EDGE_FALLTHRU
;
1941 /* We removed some paths from the cfg. */
1942 if (dom_computed
[CDI_DOMINATORS
] >= DOM_CONS_OK
)
1943 dom_computed
[CDI_DOMINATORS
] = DOM_CONS_OK
;
1949 /* Given a control block BB and a constant value VAL, return the edge that
1950 will be taken out of the block. If VAL does not match a unique edge,
1951 NULL is returned. */
1954 find_taken_edge (basic_block bb
, tree val
)
1958 stmt
= last_stmt (bb
);
1960 #if defined ENABLE_CHECKING
1961 if (stmt
== NULL_TREE
|| !is_ctrl_stmt (stmt
))
1965 /* If VAL is not a constant, we can't determine which edge might
1967 if (val
== NULL
|| !really_constant_p (val
))
1970 if (TREE_CODE (stmt
) == COND_EXPR
)
1971 return find_taken_edge_cond_expr (bb
, val
);
1973 if (TREE_CODE (stmt
) == SWITCH_EXPR
)
1974 return find_taken_edge_switch_expr (bb
, val
);
1980 /* Given a constant value VAL and the entry block BB to a COND_EXPR
1981 statement, determine which of the two edges will be taken out of the
1982 block. Return NULL if either edge may be taken. */
1985 find_taken_edge_cond_expr (basic_block bb
, tree val
)
1987 edge true_edge
, false_edge
;
1989 extract_true_false_edges_from_block (bb
, &true_edge
, &false_edge
);
1991 /* If both edges of the branch lead to the same basic block, it doesn't
1992 matter which edge is taken. */
1993 if (true_edge
->dest
== false_edge
->dest
)
1996 /* Otherwise, try to determine which branch of the if() will be taken.
1997 If VAL is a constant but it can't be reduced to a 0 or a 1, then
1998 we don't really know which edge will be taken at runtime. This
1999 may happen when comparing addresses (e.g., if (&var1 == 4)). */
2000 if (integer_nonzerop (val
))
2002 else if (integer_zerop (val
))
2009 /* Given a constant value VAL and the entry block BB to a SWITCH_EXPR
2010 statement, determine which edge will be taken out of the block. Return
2011 NULL if any edge may be taken. */
2014 find_taken_edge_switch_expr (basic_block bb
, tree val
)
2016 tree switch_expr
, taken_case
;
2017 basic_block dest_bb
;
2020 if (TREE_CODE (val
) != INTEGER_CST
)
2023 switch_expr
= last_stmt (bb
);
2024 taken_case
= find_case_label_for_value (switch_expr
, val
);
2025 dest_bb
= label_to_block (CASE_LABEL (taken_case
));
2027 e
= find_edge (bb
, dest_bb
);
2034 /* Return the CASE_LABEL_EXPR that SWITCH_EXPR will take for VAL.
2035 We can make optimal use here of the fact that the case labels are
2036 sorted: We can do a binary search for a case matching VAL. */
2039 find_case_label_for_value (tree switch_expr
, tree val
)
2041 tree vec
= SWITCH_LABELS (switch_expr
);
2042 size_t low
, high
, n
= TREE_VEC_LENGTH (vec
);
2043 tree default_case
= TREE_VEC_ELT (vec
, n
- 1);
2045 for (low
= -1, high
= n
- 1; high
- low
> 1; )
2047 size_t i
= (high
+ low
) / 2;
2048 tree t
= TREE_VEC_ELT (vec
, i
);
2051 /* Cache the result of comparing CASE_LOW and val. */
2052 cmp
= tree_int_cst_compare (CASE_LOW (t
), val
);
2059 if (CASE_HIGH (t
) == NULL
)
2061 /* A singe-valued case label. */
2067 /* A case range. We can only handle integer ranges. */
2068 if (cmp
<= 0 && tree_int_cst_compare (CASE_HIGH (t
), val
) >= 0)
2073 return default_case
;
2077 /* If all the PHI nodes in DEST have alternatives for E1 and E2 and
2078 those alternatives are equal in each of the PHI nodes, then return
2079 true, else return false. */
2082 phi_alternatives_equal (basic_block dest
, edge e1
, edge e2
)
2084 tree phi
, val1
, val2
;
2087 for (phi
= phi_nodes (dest
); phi
; phi
= TREE_CHAIN (phi
))
2089 n1
= phi_arg_from_edge (phi
, e1
);
2090 n2
= phi_arg_from_edge (phi
, e2
);
2092 #ifdef ENABLE_CHECKING
2093 if (n1
< 0 || n2
< 0)
2097 val1
= PHI_ARG_DEF (phi
, n1
);
2098 val2
= PHI_ARG_DEF (phi
, n2
);
2100 if (!operand_equal_p (val1
, val2
, 0))
2108 /* Computing the Dominance Frontier:
2110 As described in Morgan, section 3.5, this may be done simply by
2111 walking the dominator tree bottom-up, computing the frontier for
2112 the children before the parent. When considering a block B,
2113 there are two cases:
2115 (1) A flow graph edge leaving B that does not lead to a child
2116 of B in the dominator tree must be a block that is either equal
2117 to B or not dominated by B. Such blocks belong in the frontier
2120 (2) Consider a block X in the frontier of one of the children C
2121 of B. If X is not equal to B and is not dominated by B, it
2122 is in the frontier of B. */
2125 compute_dominance_frontiers_1 (bitmap
*frontiers
, basic_block bb
, sbitmap done
)
2130 SET_BIT (done
, bb
->index
);
2132 /* Do the frontier of the children first. Not all children in the
2133 dominator tree (blocks dominated by this one) are children in the
2134 CFG, so check all blocks. */
2135 for (c
= first_dom_son (CDI_DOMINATORS
, bb
);
2137 c
= next_dom_son (CDI_DOMINATORS
, c
))
2139 if (! TEST_BIT (done
, c
->index
))
2140 compute_dominance_frontiers_1 (frontiers
, c
, done
);
2143 /* Find blocks conforming to rule (1) above. */
2144 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
2146 if (e
->dest
== EXIT_BLOCK_PTR
)
2148 if (get_immediate_dominator (CDI_DOMINATORS
, e
->dest
) != bb
)
2149 bitmap_set_bit (frontiers
[bb
->index
], e
->dest
->index
);
2152 /* Find blocks conforming to rule (2). */
2153 for (c
= first_dom_son (CDI_DOMINATORS
, bb
);
2155 c
= next_dom_son (CDI_DOMINATORS
, c
))
2159 EXECUTE_IF_SET_IN_BITMAP (frontiers
[c
->index
], 0, x
,
2161 if (get_immediate_dominator (CDI_DOMINATORS
, BASIC_BLOCK (x
)) != bb
)
2162 bitmap_set_bit (frontiers
[bb
->index
], x
);
2169 compute_dominance_frontiers (bitmap
*frontiers
)
2171 sbitmap done
= sbitmap_alloc (last_basic_block
);
2173 timevar_push (TV_DOM_FRONTIERS
);
2175 sbitmap_zero (done
);
2177 compute_dominance_frontiers_1 (frontiers
, ENTRY_BLOCK_PTR
->succ
->dest
, done
);
2179 sbitmap_free (done
);
2181 timevar_pop (TV_DOM_FRONTIERS
);
2186 /*---------------------------------------------------------------------------
2188 ---------------------------------------------------------------------------*/
2190 /* Dump tree-specific information of block BB to file OUTF. */
2193 tree_dump_bb (basic_block bb
, FILE *outf
, int indent
)
2195 dump_generic_bb (outf
, bb
, indent
, TDF_VOPS
);
2199 /* Dump a basic block on stderr. */
2202 debug_tree_bb (basic_block bb
)
2204 dump_bb (bb
, stderr
, 0);
2208 /* Dump basic block with index N on stderr. */
2211 debug_tree_bb_n (int n
)
2213 debug_tree_bb (BASIC_BLOCK (n
));
2214 return BASIC_BLOCK (n
);
2218 /* Dump the CFG on stderr.
2220 FLAGS are the same used by the tree dumping functions
2221 (see TDF_* in tree.h). */
2224 debug_tree_cfg (int flags
)
2226 dump_tree_cfg (stderr
, flags
);
2230 /* Dump the program showing basic block boundaries on the given FILE.
2232 FLAGS are the same used by the tree dumping functions (see TDF_* in
2236 dump_tree_cfg (FILE *file
, int flags
)
2238 if (flags
& TDF_DETAILS
)
2240 const char *funcname
2241 = lang_hooks
.decl_printable_name (current_function_decl
, 2);
2244 fprintf (file
, ";; Function %s\n\n", funcname
);
2245 fprintf (file
, ";; \n%d basic blocks, %d edges, last basic block %d.\n\n",
2246 n_basic_blocks
, n_edges
, last_basic_block
);
2248 brief_dump_cfg (file
);
2249 fprintf (file
, "\n");
2252 if (flags
& TDF_STATS
)
2253 dump_cfg_stats (file
);
2255 dump_function_to_file (current_function_decl
, file
, flags
| TDF_BLOCKS
);
2259 /* Dump CFG statistics on FILE. */
2262 dump_cfg_stats (FILE *file
)
2264 static long max_num_merged_labels
= 0;
2265 unsigned long size
, total
= 0;
2268 const char * const fmt_str
= "%-30s%-13s%12s\n";
2269 const char * const fmt_str_1
= "%-30s%13lu%11lu%c\n";
2270 const char * const fmt_str_3
= "%-43s%11lu%c\n";
2271 const char *funcname
2272 = lang_hooks
.decl_printable_name (current_function_decl
, 2);
2275 fprintf (file
, "\nCFG Statistics for %s\n\n", funcname
);
2277 fprintf (file
, "---------------------------------------------------------\n");
2278 fprintf (file
, fmt_str
, "", " Number of ", "Memory");
2279 fprintf (file
, fmt_str
, "", " instances ", "used ");
2280 fprintf (file
, "---------------------------------------------------------\n");
2282 size
= n_basic_blocks
* sizeof (struct basic_block_def
);
2284 fprintf (file
, fmt_str_1
, "Basic blocks", n_basic_blocks
, SCALE (size
),
2291 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
2294 size
= n_edges
* sizeof (struct edge_def
);
2296 fprintf (file
, fmt_str_1
, "Edges", n_edges
, SCALE (size
), LABEL (size
));
2298 size
= n_basic_blocks
* sizeof (struct bb_ann_d
);
2300 fprintf (file
, fmt_str_1
, "Basic block annotations", n_basic_blocks
,
2301 SCALE (size
), LABEL (size
));
2303 fprintf (file
, "---------------------------------------------------------\n");
2304 fprintf (file
, fmt_str_3
, "Total memory used by CFG data", SCALE (total
),
2306 fprintf (file
, "---------------------------------------------------------\n");
2307 fprintf (file
, "\n");
2309 if (cfg_stats
.num_merged_labels
> max_num_merged_labels
)
2310 max_num_merged_labels
= cfg_stats
.num_merged_labels
;
2312 fprintf (file
, "Coalesced label blocks: %ld (Max so far: %ld)\n",
2313 cfg_stats
.num_merged_labels
, max_num_merged_labels
);
2315 fprintf (file
, "\n");
2319 /* Dump CFG statistics on stderr. Keep extern so that it's always
2320 linked in the final executable. */
2323 debug_cfg_stats (void)
2325 dump_cfg_stats (stderr
);
2329 /* Dump the flowgraph to a .vcg FILE. */
2332 tree_cfg2vcg (FILE *file
)
2336 const char *funcname
2337 = lang_hooks
.decl_printable_name (current_function_decl
, 2);
2339 /* Write the file header. */
2340 fprintf (file
, "graph: { title: \"%s\"\n", funcname
);
2341 fprintf (file
, "node: { title: \"ENTRY\" label: \"ENTRY\" }\n");
2342 fprintf (file
, "node: { title: \"EXIT\" label: \"EXIT\" }\n");
2344 /* Write blocks and edges. */
2345 for (e
= ENTRY_BLOCK_PTR
->succ
; e
; e
= e
->succ_next
)
2347 fprintf (file
, "edge: { sourcename: \"ENTRY\" targetname: \"%d\"",
2350 if (e
->flags
& EDGE_FAKE
)
2351 fprintf (file
, " linestyle: dotted priority: 10");
2353 fprintf (file
, " linestyle: solid priority: 100");
2355 fprintf (file
, " }\n");
2361 enum tree_code head_code
, end_code
;
2362 const char *head_name
, *end_name
;
2365 tree first
= first_stmt (bb
);
2366 tree last
= last_stmt (bb
);
2370 head_code
= TREE_CODE (first
);
2371 head_name
= tree_code_name
[head_code
];
2372 head_line
= get_lineno (first
);
2375 head_name
= "no-statement";
2379 end_code
= TREE_CODE (last
);
2380 end_name
= tree_code_name
[end_code
];
2381 end_line
= get_lineno (last
);
2384 end_name
= "no-statement";
2386 fprintf (file
, "node: { title: \"%d\" label: \"#%d\\n%s (%d)\\n%s (%d)\"}\n",
2387 bb
->index
, bb
->index
, head_name
, head_line
, end_name
,
2390 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
2392 if (e
->dest
== EXIT_BLOCK_PTR
)
2393 fprintf (file
, "edge: { sourcename: \"%d\" targetname: \"EXIT\"", bb
->index
);
2395 fprintf (file
, "edge: { sourcename: \"%d\" targetname: \"%d\"", bb
->index
, e
->dest
->index
);
2397 if (e
->flags
& EDGE_FAKE
)
2398 fprintf (file
, " priority: 10 linestyle: dotted");
2400 fprintf (file
, " priority: 100 linestyle: solid");
2402 fprintf (file
, " }\n");
2405 if (bb
->next_bb
!= EXIT_BLOCK_PTR
)
2409 fputs ("}\n\n", file
);
2414 /*---------------------------------------------------------------------------
2415 Miscellaneous helpers
2416 ---------------------------------------------------------------------------*/
2418 /* Return true if T represents a stmt that always transfers control. */
2421 is_ctrl_stmt (tree t
)
2423 return (TREE_CODE (t
) == COND_EXPR
2424 || TREE_CODE (t
) == SWITCH_EXPR
2425 || TREE_CODE (t
) == GOTO_EXPR
2426 || TREE_CODE (t
) == RETURN_EXPR
2427 || TREE_CODE (t
) == RESX_EXPR
);
2431 /* Return true if T is a statement that may alter the flow of control
2432 (e.g., a call to a non-returning function). */
2435 is_ctrl_altering_stmt (tree t
)
2439 #if defined ENABLE_CHECKING
2444 switch (TREE_CODE (t
))
2447 /* A MODIFY_EXPR with a rhs of a call has the characteristics
2449 call
= TREE_OPERAND (t
, 1);
2450 if (TREE_CODE (call
) != CALL_EXPR
)
2455 /* A non-pure/const CALL_EXPR alters flow control if the current
2456 function has nonlocal labels. */
2457 if (TREE_SIDE_EFFECTS (t
)
2458 && current_function_has_nonlocal_label
)
2461 /* A CALL_EXPR also alters control flow if it does not return. */
2462 if (call_expr_flags (call
) & (ECF_NORETURN
| ECF_LONGJMP
))
2470 /* If a statement can throw, it alters control flow. */
2471 return tree_can_throw_internal (t
);
2475 /* Return true if T is a computed goto. */
2478 computed_goto_p (tree t
)
2480 return (TREE_CODE (t
) == GOTO_EXPR
2481 && TREE_CODE (GOTO_DESTINATION (t
)) != LABEL_DECL
);
2485 /* Checks whether EXPR is a simple local goto. */
2488 simple_goto_p (tree expr
)
2490 return (TREE_CODE (expr
) == GOTO_EXPR
2491 && TREE_CODE (GOTO_DESTINATION (expr
)) == LABEL_DECL
2492 && (decl_function_context (GOTO_DESTINATION (expr
))
2493 == current_function_decl
));
2497 /* Return true if T should start a new basic block. PREV_T is the
2498 statement preceding T. It is used when T is a label or a case label.
2499 Labels should only start a new basic block if their previous statement
2500 wasn't a label. Otherwise, sequence of labels would generate
2501 unnecessary basic blocks that only contain a single label. */
2504 stmt_starts_bb_p (tree t
, tree prev_t
)
2506 enum tree_code code
;
2511 /* LABEL_EXPRs start a new basic block only if the preceding
2512 statement wasn't a label of the same type. This prevents the
2513 creation of consecutive blocks that have nothing but a single
2515 code
= TREE_CODE (t
);
2516 if (code
== LABEL_EXPR
)
2518 /* Nonlocal and computed GOTO targets always start a new block. */
2519 if (code
== LABEL_EXPR
2520 && (DECL_NONLOCAL (LABEL_EXPR_LABEL (t
))
2521 || FORCED_LABEL (LABEL_EXPR_LABEL (t
))))
2524 if (prev_t
&& TREE_CODE (prev_t
) == code
)
2526 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (prev_t
)))
2529 cfg_stats
.num_merged_labels
++;
2540 /* Return true if T should end a basic block. */
2543 stmt_ends_bb_p (tree t
)
2545 return is_ctrl_stmt (t
) || is_ctrl_altering_stmt (t
);
2549 /* Add gotos that used to be represented implicitly in the CFG. */
2552 disband_implicit_edges (void)
2555 block_stmt_iterator last
;
2557 tree stmt
, label
, forward
;
2561 last
= bsi_last (bb
);
2562 stmt
= last_stmt (bb
);
2564 if (stmt
&& TREE_CODE (stmt
) == COND_EXPR
)
2566 /* Remove superfluous gotos from COND_EXPR branches. Moved
2567 from cfg_remove_useless_stmts here since it violates the
2568 invariants for tree--cfg correspondence and thus fits better
2569 here where we do it anyway. */
2570 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
2572 if (e
->dest
!= bb
->next_bb
)
2575 if (e
->flags
& EDGE_TRUE_VALUE
)
2576 COND_EXPR_THEN (stmt
) = build_empty_stmt ();
2577 else if (e
->flags
& EDGE_FALSE_VALUE
)
2578 COND_EXPR_ELSE (stmt
) = build_empty_stmt ();
2581 e
->flags
|= EDGE_FALLTHRU
;
2587 if (stmt
&& TREE_CODE (stmt
) == RETURN_EXPR
)
2589 /* Remove the RETURN_EXPR if we may fall though to the exit
2592 || bb
->succ
->succ_next
2593 || bb
->succ
->dest
!= EXIT_BLOCK_PTR
)
2596 if (bb
->next_bb
== EXIT_BLOCK_PTR
2597 && !TREE_OPERAND (stmt
, 0))
2600 bb
->succ
->flags
|= EDGE_FALLTHRU
;
2605 /* There can be no fallthru edge if the last statement is a control
2607 if (stmt
&& is_ctrl_stmt (stmt
))
2610 /* Find a fallthru edge and emit the goto if necessary. */
2611 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
2612 if (e
->flags
& EDGE_FALLTHRU
)
2616 || e
->dest
== bb
->next_bb
)
2619 if (e
->dest
== EXIT_BLOCK_PTR
)
2622 label
= tree_block_label (e
->dest
);
2624 /* If this is a goto to a goto, jump to the final destination.
2625 Handles unfactoring of the computed jumps.
2626 ??? Why bother putting this back together when rtl is just
2627 about to take it apart again? */
2628 forward
= last_and_only_stmt (e
->dest
);
2630 && TREE_CODE (forward
) == GOTO_EXPR
)
2631 label
= GOTO_DESTINATION (forward
);
2633 bsi_insert_after (&last
,
2634 build1 (GOTO_EXPR
, void_type_node
, label
),
2636 e
->flags
&= ~EDGE_FALLTHRU
;
2641 /* Remove all the blocks and edges that make up the flowgraph. */
2644 delete_tree_cfg (void)
2646 if (n_basic_blocks
> 0)
2647 free_blocks_annotations ();
2649 free_basic_block_vars ();
2650 basic_block_info
= NULL
;
2651 label_to_block_map
= NULL
;
2656 /* Return the first statement in basic block BB. */
2659 first_stmt (basic_block bb
)
2661 block_stmt_iterator i
= bsi_start (bb
);
2662 return !bsi_end_p (i
) ? bsi_stmt (i
) : NULL_TREE
;
2666 /* Return the last statement in basic block BB. */
2669 last_stmt (basic_block bb
)
2671 block_stmt_iterator b
= bsi_last (bb
);
2672 return !bsi_end_p (b
) ? bsi_stmt (b
) : NULL_TREE
;
2676 /* Return a pointer to the last statement in block BB. */
2679 last_stmt_ptr (basic_block bb
)
2681 block_stmt_iterator last
= bsi_last (bb
);
2682 return !bsi_end_p (last
) ? bsi_stmt_ptr (last
) : NULL
;
2686 /* Return the last statement of an otherwise empty block. Return NULL
2687 if the block is totally empty, or if it contains more than one
2691 last_and_only_stmt (basic_block bb
)
2693 block_stmt_iterator i
= bsi_last (bb
);
2699 last
= bsi_stmt (i
);
2704 /* Empty statements should no longer appear in the instruction stream.
2705 Everything that might have appeared before should be deleted by
2706 remove_useless_stmts, and the optimizers should just bsi_remove
2707 instead of smashing with build_empty_stmt.
2709 Thus the only thing that should appear here in a block containing
2710 one executable statement is a label. */
2711 prev
= bsi_stmt (i
);
2712 if (TREE_CODE (prev
) == LABEL_EXPR
)
2719 /* Mark BB as the basic block holding statement T. */
2722 set_bb_for_stmt (tree t
, basic_block bb
)
2724 if (TREE_CODE (t
) == STATEMENT_LIST
)
2726 tree_stmt_iterator i
;
2727 for (i
= tsi_start (t
); !tsi_end_p (i
); tsi_next (&i
))
2728 set_bb_for_stmt (tsi_stmt (i
), bb
);
2732 stmt_ann_t ann
= get_stmt_ann (t
);
2735 /* If the statement is a label, add the label to block-to-labels map
2736 so that we can speed up edge creation for GOTO_EXPRs. */
2737 if (TREE_CODE (t
) == LABEL_EXPR
)
2741 t
= LABEL_EXPR_LABEL (t
);
2742 uid
= LABEL_DECL_UID (t
);
2745 LABEL_DECL_UID (t
) = uid
= cfun
->last_label_uid
++;
2746 if (VARRAY_SIZE (label_to_block_map
) <= (unsigned) uid
)
2747 VARRAY_GROW (label_to_block_map
, 3 * uid
/ 2);
2751 #ifdef ENABLE_CHECKING
2752 /* We're moving an existing label. Make sure that we've
2753 removed it from the old block. */
2754 if (bb
&& VARRAY_BB (label_to_block_map
, uid
))
2758 VARRAY_BB (label_to_block_map
, uid
) = bb
;
2764 /* Insert statement (or statement list) T before the statement
2765 pointed-to by iterator I. M specifies how to update iterator I
2766 after insertion (see enum bsi_iterator_update). */
2769 bsi_insert_before (block_stmt_iterator
*i
, tree t
, enum bsi_iterator_update m
)
2771 set_bb_for_stmt (t
, i
->bb
);
2773 tsi_link_before (&i
->tsi
, t
, m
);
2777 /* Insert statement (or statement list) T after the statement
2778 pointed-to by iterator I. M specifies how to update iterator I
2779 after insertion (see enum bsi_iterator_update). */
2782 bsi_insert_after (block_stmt_iterator
*i
, tree t
, enum bsi_iterator_update m
)
2784 set_bb_for_stmt (t
, i
->bb
);
2786 tsi_link_after (&i
->tsi
, t
, m
);
2790 /* Remove the statement pointed to by iterator I. The iterator is updated
2791 to the next statement. */
2794 bsi_remove (block_stmt_iterator
*i
)
2796 tree t
= bsi_stmt (*i
);
2797 set_bb_for_stmt (t
, NULL
);
2799 tsi_delink (&i
->tsi
);
2803 /* Move the statement at FROM so it comes right after the statement at TO. */
2806 bsi_move_after (block_stmt_iterator
*from
, block_stmt_iterator
*to
)
2808 tree stmt
= bsi_stmt (*from
);
2810 bsi_insert_after (to
, stmt
, BSI_SAME_STMT
);
2814 /* Move the statement at FROM so it comes right before the statement at TO. */
2817 bsi_move_before (block_stmt_iterator
*from
, block_stmt_iterator
*to
)
2819 tree stmt
= bsi_stmt (*from
);
2821 bsi_insert_before (to
, stmt
, BSI_SAME_STMT
);
2825 /* Move the statement at FROM to the end of basic block BB. */
2828 bsi_move_to_bb_end (block_stmt_iterator
*from
, basic_block bb
)
2830 block_stmt_iterator last
= bsi_last (bb
);
2832 /* Have to check bsi_end_p because it could be an empty block. */
2833 if (!bsi_end_p (last
) && is_ctrl_stmt (bsi_stmt (last
)))
2834 bsi_move_before (from
, &last
);
2836 bsi_move_after (from
, &last
);
2840 /* Replace the contents of the statement pointed to by iterator BSI
2841 with STMT. If PRESERVE_EH_INFO is true, the exception handling
2842 information of the original statement is preserved. */
2845 bsi_replace (const block_stmt_iterator
*bsi
, tree stmt
, bool preserve_eh_info
)
2848 tree orig_stmt
= bsi_stmt (*bsi
);
2850 SET_EXPR_LOCUS (stmt
, EXPR_LOCUS (orig_stmt
));
2851 set_bb_for_stmt (stmt
, bsi
->bb
);
2853 /* Preserve EH region information from the original statement, if
2854 requested by the caller. */
2855 if (preserve_eh_info
)
2857 eh_region
= lookup_stmt_eh_region (orig_stmt
);
2859 add_stmt_to_eh_region (stmt
, eh_region
);
2862 *bsi_stmt_ptr (*bsi
) = stmt
;
2867 /* Insert the statement pointed-to by BSI into edge E. Every attempt
2868 is made to place the statement in an existing basic block, but
2869 sometimes that isn't possible. When it isn't possible, the edge is
2870 split and the statement is added to the new block.
2872 In all cases, the returned *BSI points to the correct location. The
2873 return value is true if insertion should be done after the location,
2874 or false if it should be done before the location. */
2877 tree_find_edge_insert_loc (edge e
, block_stmt_iterator
*bsi
)
2879 basic_block dest
, src
;
2885 /* If the destination has one predecessor which has no PHI nodes,
2886 insert there. Except for the exit block.
2888 The requirement for no PHI nodes could be relaxed. Basically we
2889 would have to examine the PHIs to prove that none of them used
2890 the value set by the statement we want to insert on E. That
2891 hardly seems worth the effort. */
2892 if (dest
->pred
->pred_next
== NULL
2893 && ! phi_nodes (dest
)
2894 && dest
!= EXIT_BLOCK_PTR
)
2896 *bsi
= bsi_start (dest
);
2897 if (bsi_end_p (*bsi
))
2900 /* Make sure we insert after any leading labels. */
2901 tmp
= bsi_stmt (*bsi
);
2902 while (TREE_CODE (tmp
) == LABEL_EXPR
)
2905 if (bsi_end_p (*bsi
))
2907 tmp
= bsi_stmt (*bsi
);
2910 if (bsi_end_p (*bsi
))
2912 *bsi
= bsi_last (dest
);
2919 /* If the source has one successor, the edge is not abnormal and
2920 the last statement does not end a basic block, insert there.
2921 Except for the entry block. */
2923 if ((e
->flags
& EDGE_ABNORMAL
) == 0
2924 && src
->succ
->succ_next
== NULL
2925 && src
!= ENTRY_BLOCK_PTR
)
2927 *bsi
= bsi_last (src
);
2928 if (bsi_end_p (*bsi
))
2931 tmp
= bsi_stmt (*bsi
);
2932 if (!stmt_ends_bb_p (tmp
))
2936 /* Otherwise, create a new basic block, and split this edge. */
2937 dest
= split_edge (e
);
2943 /* This routine will commit all pending edge insertions, creating any new
2944 basic blocks which are necessary.
2946 If specified, NEW_BLOCKS returns a count of the number of new basic
2947 blocks which were created. */
2950 bsi_commit_edge_inserts (int *new_blocks
)
2956 blocks
= n_basic_blocks
;
2958 bsi_commit_edge_inserts_1 (ENTRY_BLOCK_PTR
->succ
);
2961 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
2962 bsi_commit_edge_inserts_1 (e
);
2965 *new_blocks
= n_basic_blocks
- blocks
;
2969 /* Commit insertions pending at edge E. */
2972 bsi_commit_edge_inserts_1 (edge e
)
2974 if (PENDING_STMT (e
))
2976 block_stmt_iterator bsi
;
2977 tree stmt
= PENDING_STMT (e
);
2979 PENDING_STMT (e
) = NULL_TREE
;
2981 if (tree_find_edge_insert_loc (e
, &bsi
))
2982 bsi_insert_after (&bsi
, stmt
, BSI_NEW_STMT
);
2984 bsi_insert_before (&bsi
, stmt
, BSI_NEW_STMT
);
2989 /* Add STMT to the pending list of edge E. No actual insertion is
2990 made until a call to bsi_commit_edge_inserts () is made. */
2993 bsi_insert_on_edge (edge e
, tree stmt
)
2995 append_to_statement_list (stmt
, &PENDING_STMT (e
));
2999 /* Specialized edge insertion for SSA-PRE. FIXME: This should
3000 probably disappear. The only reason it's here is because PRE needs
3001 the call to tree_find_edge_insert_loc(). */
3003 void pre_insert_on_edge (edge e
, tree stmt
);
3006 pre_insert_on_edge (edge e
, tree stmt
)
3008 block_stmt_iterator bsi
;
3010 if (PENDING_STMT (e
))
3013 if (tree_find_edge_insert_loc (e
, &bsi
))
3014 bsi_insert_after (&bsi
, stmt
, BSI_NEW_STMT
);
3016 bsi_insert_before (&bsi
, stmt
, BSI_NEW_STMT
);
3020 /*---------------------------------------------------------------------------
3021 Tree specific functions for CFG manipulation
3022 ---------------------------------------------------------------------------*/
3024 /* Split a (typically critical) edge EDGE_IN. Return the new block.
3025 Abort on abnormal edges. */
3028 tree_split_edge (edge edge_in
)
3030 basic_block new_bb
, after_bb
, dest
, src
;
3035 /* Abnormal edges cannot be split. */
3036 if (edge_in
->flags
& EDGE_ABNORMAL
)
3040 dest
= edge_in
->dest
;
3042 /* Place the new block in the block list. Try to keep the new block
3043 near its "logical" location. This is of most help to humans looking
3044 at debugging dumps. */
3045 for (e
= dest
->pred
; e
; e
= e
->pred_next
)
3046 if (e
->src
->next_bb
== dest
)
3049 after_bb
= dest
->prev_bb
;
3051 after_bb
= edge_in
->src
;
3053 new_bb
= create_empty_bb (after_bb
);
3054 new_edge
= make_edge (new_bb
, dest
, EDGE_FALLTHRU
);
3056 /* Find all the PHI arguments on the original edge, and change them to
3057 the new edge. Do it before redirection, so that the argument does not
3059 for (phi
= phi_nodes (dest
); phi
; phi
= TREE_CHAIN (phi
))
3061 num_elem
= PHI_NUM_ARGS (phi
);
3062 for (i
= 0; i
< num_elem
; i
++)
3063 if (PHI_ARG_EDGE (phi
, i
) == edge_in
)
3065 PHI_ARG_EDGE (phi
, i
) = new_edge
;
3070 if (!redirect_edge_and_branch (edge_in
, new_bb
))
3073 if (PENDING_STMT (edge_in
))
3080 /* Return true when BB has label LABEL in it. */
3083 has_label_p (basic_block bb
, tree label
)
3085 block_stmt_iterator bsi
;
3087 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
3089 tree stmt
= bsi_stmt (bsi
);
3091 if (TREE_CODE (stmt
) != LABEL_EXPR
)
3093 if (LABEL_EXPR_LABEL (stmt
) == label
)
3100 /* Callback for walk_tree, check that all elements with address taken are
3101 properly noticed as such. */
3104 verify_expr (tree
*tp
, int *walk_subtrees ATTRIBUTE_UNUSED
,
3105 void *data ATTRIBUTE_UNUSED
)
3112 switch (TREE_CODE (t
))
3115 if (SSA_NAME_IN_FREE_LIST (t
))
3117 error ("SSA name in freelist but still referenced");
3123 x
= TREE_OPERAND (t
, 0);
3124 if (TREE_CODE (x
) == BIT_FIELD_REF
3125 && is_gimple_reg (TREE_OPERAND (x
, 0)))
3127 error ("GIMPLE register modified with BIT_FIELD_REF");
3133 x
= TREE_OPERAND (t
, 0);
3134 while (TREE_CODE (x
) == ARRAY_REF
3135 || TREE_CODE (x
) == COMPONENT_REF
3136 || TREE_CODE (x
) == REALPART_EXPR
3137 || TREE_CODE (x
) == IMAGPART_EXPR
)
3138 x
= TREE_OPERAND (x
, 0);
3139 if (TREE_CODE (x
) != VAR_DECL
&& TREE_CODE (x
) != PARM_DECL
)
3141 if (!TREE_ADDRESSABLE (x
))
3143 error ("address taken, but ADDRESSABLE bit not set");
3149 x
= TREE_OPERAND (t
, 0);
3150 if (TREE_CODE (TREE_TYPE (x
)) != BOOLEAN_TYPE
)
3152 error ("non-boolean used in condition");
3159 case FIX_TRUNC_EXPR
:
3161 case FIX_FLOOR_EXPR
:
3162 case FIX_ROUND_EXPR
:
3167 case NON_LVALUE_EXPR
:
3168 case TRUTH_NOT_EXPR
:
3169 x
= TREE_OPERAND (t
, 0);
3170 /* We check for constants explicitly since they are not considered
3171 gimple invariants if they overflowed. */
3172 if (TREE_CODE_CLASS (TREE_CODE (x
)) != 'c'
3173 && !is_gimple_val (x
))
3175 error ("Invalid operand to unary operator");
3190 case UNORDERED_EXPR
:
3201 case TRUNC_DIV_EXPR
:
3203 case FLOOR_DIV_EXPR
:
3204 case ROUND_DIV_EXPR
:
3205 case TRUNC_MOD_EXPR
:
3207 case FLOOR_MOD_EXPR
:
3208 case ROUND_MOD_EXPR
:
3210 case EXACT_DIV_EXPR
:
3220 x
= TREE_OPERAND (t
, 0);
3221 /* We check for constants explicitly since they are not considered
3222 gimple invariants if they overflowed. */
3223 if (TREE_CODE_CLASS (TREE_CODE (x
)) != 'c'
3224 && !is_gimple_val (x
))
3226 error ("Invalid operand to binary operator");
3229 x
= TREE_OPERAND (t
, 1);
3230 /* We check for constants explicitly since they are not considered
3231 gimple invariants if they overflowed. */
3232 if (TREE_CODE_CLASS (TREE_CODE (x
)) != 'c'
3233 && !is_gimple_val (x
))
3235 error ("Invalid operand to binary operator");
3247 /* Verify STMT, return true if STMT is not in GIMPLE form.
3248 TODO: Implement type checking. */
3251 verify_stmt (tree stmt
)
3255 if (!is_gimple_stmt (stmt
))
3257 error ("Is not a valid GIMPLE statement.");
3258 debug_generic_stmt (stmt
);
3262 addr
= walk_tree (&stmt
, verify_expr
, NULL
, NULL
);
3265 debug_generic_stmt (addr
);
3273 /* Return true when the T can be shared. */
3276 tree_node_can_be_shared (tree t
)
3278 if (TYPE_P (t
) || DECL_P (t
)
3279 /* We check for constants explicitly since they are not considered
3280 gimple invariants if they overflowed. */
3281 || TREE_CODE_CLASS (TREE_CODE (t
)) == 'c'
3282 || is_gimple_min_invariant (t
)
3283 || TREE_CODE (t
) == SSA_NAME
)
3286 while ((TREE_CODE (t
) == ARRAY_REF
3287 /* We check for constants explicitly since they are not considered
3288 gimple invariants if they overflowed. */
3289 && (TREE_CODE_CLASS (TREE_CODE (TREE_OPERAND (t
, 1))) == 'c'
3290 || is_gimple_min_invariant (TREE_OPERAND (t
, 1))))
3291 || (TREE_CODE (t
) == COMPONENT_REF
3292 || TREE_CODE (t
) == REALPART_EXPR
3293 || TREE_CODE (t
) == IMAGPART_EXPR
))
3294 t
= TREE_OPERAND (t
, 0);
3303 /* Called via walk_trees. Verify tree sharing. */
3306 verify_node_sharing (tree
* tp
, int *walk_subtrees
, void *data
)
3308 htab_t htab
= (htab_t
) data
;
3311 if (tree_node_can_be_shared (*tp
))
3313 *walk_subtrees
= false;
3317 slot
= htab_find_slot (htab
, *tp
, INSERT
);
3326 /* Verify the GIMPLE statement chain. */
3332 block_stmt_iterator bsi
;
3337 timevar_push (TV_TREE_STMT_VERIFY
);
3338 htab
= htab_create (37, htab_hash_pointer
, htab_eq_pointer
, NULL
);
3345 for (phi
= phi_nodes (bb
); phi
; phi
= TREE_CHAIN (phi
))
3347 int phi_num_args
= PHI_NUM_ARGS (phi
);
3349 for (i
= 0; i
< phi_num_args
; i
++)
3351 tree t
= PHI_ARG_DEF (phi
, i
);
3354 /* Addressable variables do have SSA_NAMEs but they
3355 are not considered gimple values. */
3356 if (TREE_CODE (t
) != SSA_NAME
3357 && TREE_CODE (t
) != FUNCTION_DECL
3358 && !is_gimple_val (t
))
3360 error ("PHI def is not a GIMPLE value");
3361 debug_generic_stmt (phi
);
3362 debug_generic_stmt (t
);
3366 addr
= walk_tree (&t
, verify_expr
, NULL
, NULL
);
3369 debug_generic_stmt (addr
);
3373 addr
= walk_tree (&t
, verify_node_sharing
, htab
, NULL
);
3376 error ("Incorrect sharing of tree nodes");
3377 debug_generic_stmt (phi
);
3378 debug_generic_stmt (addr
);
3384 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
3386 tree stmt
= bsi_stmt (bsi
);
3387 err
|= verify_stmt (stmt
);
3388 addr
= walk_tree (&stmt
, verify_node_sharing
, htab
, NULL
);
3391 error ("Incorrect sharing of tree nodes");
3392 debug_generic_stmt (stmt
);
3393 debug_generic_stmt (addr
);
3400 internal_error ("verify_stmts failed.");
3403 timevar_pop (TV_TREE_STMT_VERIFY
);
3407 /* Verifies that the flow information is OK. */
3410 tree_verify_flow_info (void)
3414 block_stmt_iterator bsi
;
3418 if (ENTRY_BLOCK_PTR
->stmt_list
)
3420 error ("ENTRY_BLOCK has a statement list associated with it\n");
3424 if (EXIT_BLOCK_PTR
->stmt_list
)
3426 error ("EXIT_BLOCK has a statement list associated with it\n");
3430 for (e
= EXIT_BLOCK_PTR
->pred
; e
; e
= e
->pred_next
)
3431 if (e
->flags
& EDGE_FALLTHRU
)
3433 error ("Fallthru to exit from bb %d\n", e
->src
->index
);
3439 bool found_ctrl_stmt
= false;
3441 /* Skip labels on the start of basic block. */
3442 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
3444 if (TREE_CODE (bsi_stmt (bsi
)) != LABEL_EXPR
)
3447 if (label_to_block (LABEL_EXPR_LABEL (bsi_stmt (bsi
))) != bb
)
3449 error ("Label %s to block does not match in bb %d\n",
3450 IDENTIFIER_POINTER (DECL_NAME (bsi_stmt (bsi
))),
3455 if (decl_function_context (LABEL_EXPR_LABEL (bsi_stmt (bsi
)))
3456 != current_function_decl
)
3458 error ("Label %s has incorrect context in bb %d\n",
3459 IDENTIFIER_POINTER (DECL_NAME (bsi_stmt (bsi
))),
3465 /* Verify that body of basic block BB is free of control flow. */
3466 for (; !bsi_end_p (bsi
); bsi_next (&bsi
))
3468 tree stmt
= bsi_stmt (bsi
);
3470 if (found_ctrl_stmt
)
3472 error ("Control flow in the middle of basic block %d\n",
3477 if (stmt_ends_bb_p (stmt
))
3478 found_ctrl_stmt
= true;
3480 if (TREE_CODE (stmt
) == LABEL_EXPR
)
3482 error ("Label %s in the middle of basic block %d\n",
3483 IDENTIFIER_POINTER (DECL_NAME (stmt
)),
3488 bsi
= bsi_last (bb
);
3489 if (bsi_end_p (bsi
))
3492 stmt
= bsi_stmt (bsi
);
3494 if (is_ctrl_stmt (stmt
))
3496 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
3497 if (e
->flags
& EDGE_FALLTHRU
)
3499 error ("Fallthru edge after a control statement in bb %d \n",
3505 switch (TREE_CODE (stmt
))
3511 if (TREE_CODE (COND_EXPR_THEN (stmt
)) != GOTO_EXPR
3512 || TREE_CODE (COND_EXPR_ELSE (stmt
)) != GOTO_EXPR
)
3514 error ("Structured COND_EXPR at the end of bb %d\n", bb
->index
);
3518 extract_true_false_edges_from_block (bb
, &true_edge
, &false_edge
);
3520 if (!true_edge
|| !false_edge
3521 || !(true_edge
->flags
& EDGE_TRUE_VALUE
)
3522 || !(false_edge
->flags
& EDGE_FALSE_VALUE
)
3523 || (true_edge
->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
))
3524 || (false_edge
->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
))
3525 || bb
->succ
->succ_next
->succ_next
)
3527 error ("Wrong outgoing edge flags at end of bb %d\n",
3532 if (!has_label_p (true_edge
->dest
,
3533 GOTO_DESTINATION (COND_EXPR_THEN (stmt
))))
3535 error ("`then' label does not match edge at end of bb %d\n",
3540 if (!has_label_p (false_edge
->dest
,
3541 GOTO_DESTINATION (COND_EXPR_ELSE (stmt
))))
3543 error ("`else' label does not match edge at end of bb %d\n",
3551 if (simple_goto_p (stmt
))
3553 error ("Explicit goto at end of bb %d\n", bb
->index
);
3558 /* FIXME. We should double check that the labels in the
3559 destination blocks have their address taken. */
3560 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
3561 if ((e
->flags
& (EDGE_FALLTHRU
| EDGE_TRUE_VALUE
3562 | EDGE_FALSE_VALUE
))
3563 || !(e
->flags
& EDGE_ABNORMAL
))
3565 error ("Wrong outgoing edge flags at end of bb %d\n",
3573 if (!bb
->succ
|| bb
->succ
->succ_next
3574 || (bb
->succ
->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
3575 | EDGE_TRUE_VALUE
| EDGE_FALSE_VALUE
)))
3577 error ("Wrong outgoing edge flags at end of bb %d\n", bb
->index
);
3580 if (bb
->succ
->dest
!= EXIT_BLOCK_PTR
)
3582 error ("Return edge does not point to exit in bb %d\n",
3594 vec
= SWITCH_LABELS (stmt
);
3595 n
= TREE_VEC_LENGTH (vec
);
3597 /* Mark all the destination basic blocks. */
3598 for (i
= 0; i
< n
; ++i
)
3600 tree lab
= CASE_LABEL (TREE_VEC_ELT (vec
, i
));
3601 basic_block label_bb
= label_to_block (lab
);
3603 if (label_bb
->aux
&& label_bb
->aux
!= (void *)1)
3605 label_bb
->aux
= (void *)1;
3608 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
3612 error ("Extra outgoing edge %d->%d\n",
3613 bb
->index
, e
->dest
->index
);
3616 e
->dest
->aux
= (void *)2;
3617 if ((e
->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
3618 | EDGE_TRUE_VALUE
| EDGE_FALSE_VALUE
)))
3620 error ("Wrong outgoing edge flags at end of bb %d\n",
3626 /* Check that we have all of them. */
3627 for (i
= 0; i
< n
; ++i
)
3629 tree lab
= CASE_LABEL (TREE_VEC_ELT (vec
, i
));
3630 basic_block label_bb
= label_to_block (lab
);
3632 if (label_bb
->aux
!= (void *)2)
3634 error ("Missing edge %i->%i\n",
3635 bb
->index
, label_bb
->index
);
3640 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
3641 e
->dest
->aux
= (void *)0;
3648 if (dom_computed
[CDI_DOMINATORS
] >= DOM_NO_FAST_QUERY
)
3649 verify_dominators (CDI_DOMINATORS
);
3655 /* Updates phi nodes after creating forwarder block joined
3656 by edge FALLTHRU. */
3659 tree_make_forwarder_block (edge fallthru
)
3662 basic_block dummy
, bb
;
3663 tree phi
, new_phi
, var
;
3665 dummy
= fallthru
->src
;
3666 bb
= fallthru
->dest
;
3668 if (!bb
->pred
->pred_next
)
3671 /* If we redirected a branch we must create new phi nodes at the
3673 for (phi
= phi_nodes (dummy
); phi
; phi
= TREE_CHAIN (phi
))
3675 var
= PHI_RESULT (phi
);
3676 new_phi
= create_phi_node (var
, bb
);
3677 SSA_NAME_DEF_STMT (var
) = new_phi
;
3678 PHI_RESULT (phi
) = make_ssa_name (SSA_NAME_VAR (var
), phi
);
3679 add_phi_arg (&new_phi
, PHI_RESULT (phi
), fallthru
);
3682 /* Ensure that the PHI node chains are in the same order. */
3683 set_phi_nodes (bb
, nreverse (phi_nodes (bb
)));
3685 /* Add the arguments we have stored on edges. */
3686 for (e
= bb
->pred
; e
; e
= e
->pred_next
)
3691 for (phi
= phi_nodes (bb
), var
= PENDING_STMT (e
);
3693 phi
= TREE_CHAIN (phi
), var
= TREE_CHAIN (var
))
3694 add_phi_arg (&phi
, TREE_VALUE (var
), e
);
3696 PENDING_STMT (e
) = NULL
;
3701 /* Return true if basic block BB does nothing except pass control
3702 flow to another block and that we can safely insert a label at
3703 the start of the successor block. */
3706 tree_forwarder_block_p (basic_block bb
)
3708 block_stmt_iterator bsi
;
3711 /* If we have already determined that this block is not forwardable,
3712 then no further checks are necessary. */
3713 if (! bb_ann (bb
)->forwardable
)
3716 /* BB must have a single outgoing normal edge. Otherwise it can not be
3717 a forwarder block. */
3719 || bb
->succ
->succ_next
3720 || bb
->succ
->dest
== EXIT_BLOCK_PTR
3721 || (bb
->succ
->flags
& EDGE_ABNORMAL
)
3722 || bb
== ENTRY_BLOCK_PTR
)
3724 bb_ann (bb
)->forwardable
= 0;
3728 /* Successors of the entry block are not forwarders. */
3729 for (e
= ENTRY_BLOCK_PTR
->succ
; e
; e
= e
->succ_next
)
3732 bb_ann (bb
)->forwardable
= 0;
3736 /* BB can not have any PHI nodes. This could potentially be relaxed
3737 early in compilation if we re-rewrote the variables appearing in
3738 any PHI nodes in forwarder blocks. */
3741 bb_ann (bb
)->forwardable
= 0;
3745 /* Now walk through the statements. We can ignore labels, anything else
3746 means this is not a forwarder block. */
3747 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
3749 tree stmt
= bsi_stmt (bsi
);
3751 switch (TREE_CODE (stmt
))
3754 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt
)))
3759 bb_ann (bb
)->forwardable
= 0;
3768 /* Thread jumps over empty statements.
3770 This code should _not_ thread over obviously equivalent conditions
3771 as that requires nontrivial updates to the SSA graph. */
3776 edge e
, next
, last
, old
;
3777 basic_block bb
, dest
, tmp
;
3780 bool retval
= false;
3783 bb_ann (bb
)->forwardable
= 1;
3785 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
, EXIT_BLOCK_PTR
, next_bb
)
3787 /* Don't waste time on unreachable blocks. */
3791 /* Nor on forwarders. */
3792 if (tree_forwarder_block_p (bb
))
3795 /* This block is now part of a forwarding path, mark it as not
3796 forwardable so that we can detect loops. This bit will be
3798 bb_ann (bb
)->forwardable
= 0;
3800 /* Examine each of our block's successors to see if it is
3802 for (e
= bb
->succ
; e
; e
= next
)
3804 next
= e
->succ_next
;
3806 /* If the edge is abnormal or its destination is not
3807 forwardable, then there's nothing to do. */
3808 if ((e
->flags
& EDGE_ABNORMAL
)
3809 || !tree_forwarder_block_p (e
->dest
))
3812 /* Now walk through as many forwarder block as possible to
3813 find the ultimate destination we want to thread our jump
3815 last
= e
->dest
->succ
;
3816 bb_ann (e
->dest
)->forwardable
= 0;
3817 for (dest
= e
->dest
->succ
->dest
;
3818 tree_forwarder_block_p (dest
);
3820 dest
= dest
->succ
->dest
)
3822 /* An infinite loop detected. We redirect the edge anyway, so
3823 that the loop is shrinked into single basic block. */
3824 if (!bb_ann (dest
)->forwardable
)
3827 if (dest
->succ
->dest
== EXIT_BLOCK_PTR
)
3830 bb_ann (dest
)->forwardable
= 0;
3833 /* Reset the forwardable marks to 1. */
3836 tmp
= tmp
->succ
->dest
)
3837 bb_ann (tmp
)->forwardable
= 1;
3839 if (dest
== e
->dest
)
3842 old
= find_edge (bb
, dest
);
3845 /* If there already is an edge, check whether the values
3846 in phi nodes differ. */
3847 if (!phi_alternatives_equal (dest
, last
, old
))
3849 /* The previous block is forwarder. Redirect our jump
3850 to that target instead since we know it has no PHI
3851 nodes that will need updating. */
3854 /* That might mean that no forwarding at all is possible. */
3855 if (dest
== e
->dest
)
3858 old
= find_edge (bb
, dest
);
3862 /* Perform the redirection. */
3864 e
= redirect_edge_and_branch (e
, dest
);
3866 /* TODO -- updating dominators in this case is simple. */
3867 free_dominance_info (CDI_DOMINATORS
);
3871 /* Update PHI nodes. We know that the new argument should
3872 have the same value as the argument associated with LAST.
3873 Otherwise we would have changed our target block above. */
3874 for (phi
= phi_nodes (dest
); phi
; phi
= TREE_CHAIN (phi
))
3876 arg
= phi_arg_from_edge (phi
, last
);
3879 add_phi_arg (&phi
, PHI_ARG_DEF (phi
, arg
), e
);
3884 /* Reset the forwardable bit on our block since it's no longer in
3885 a forwarding chain path. */
3886 bb_ann (bb
)->forwardable
= 1;
3893 /* Return a non-special label in the head of basic block BLOCK.
3894 Create one if it doesn't exist. */
3897 tree_block_label (basic_block bb
)
3899 block_stmt_iterator i
, s
= bsi_start (bb
);
3903 for (i
= s
; !bsi_end_p (i
); first
= false, bsi_next (&i
))
3905 stmt
= bsi_stmt (i
);
3906 if (TREE_CODE (stmt
) != LABEL_EXPR
)
3908 label
= LABEL_EXPR_LABEL (stmt
);
3909 if (!DECL_NONLOCAL (label
))
3912 bsi_move_before (&i
, &s
);
3917 label
= create_artificial_label ();
3918 stmt
= build1 (LABEL_EXPR
, void_type_node
, label
);
3919 bsi_insert_before (&s
, stmt
, BSI_NEW_STMT
);
3924 /* Attempt to perform edge redirection by replacing a possibly complex
3925 jump instruction by a goto or by removing the jump completely.
3926 This can apply only if all edges now point to the same block. The
3927 parameters and return values are equivalent to
3928 redirect_edge_and_branch. */
3931 tree_try_redirect_by_replacing_jump (edge e
, basic_block target
)
3933 basic_block src
= e
->src
;
3935 block_stmt_iterator b
;
3938 /* Verify that all targets will be TARGET. */
3939 for (tmp
= src
->succ
; tmp
; tmp
= tmp
->succ_next
)
3940 if (tmp
->dest
!= target
&& tmp
!= e
)
3949 stmt
= bsi_stmt (b
);
3951 if (TREE_CODE (stmt
) == COND_EXPR
3952 || TREE_CODE (stmt
) == SWITCH_EXPR
)
3955 e
= ssa_redirect_edge (e
, target
);
3956 e
->flags
= EDGE_FALLTHRU
;
3964 /* Redirect E to DEST. Return NULL on failure. Otherwise, return the
3965 edge representing the redirected branch. */
3968 tree_redirect_edge_and_branch (edge e
, basic_block dest
)
3970 basic_block bb
= e
->src
;
3971 block_stmt_iterator bsi
;
3975 if (e
->flags
& (EDGE_ABNORMAL_CALL
| EDGE_EH
))
3978 if (e
->src
!= ENTRY_BLOCK_PTR
3979 && (ret
= tree_try_redirect_by_replacing_jump (e
, dest
)))
3982 if (e
->dest
== dest
)
3985 label
= tree_block_label (dest
);
3987 bsi
= bsi_last (bb
);
3988 stmt
= bsi_end_p (bsi
) ? NULL
: bsi_stmt (bsi
);
3990 switch (stmt
? TREE_CODE (stmt
) : ERROR_MARK
)
3993 stmt
= (e
->flags
& EDGE_TRUE_VALUE
3994 ? COND_EXPR_THEN (stmt
)
3995 : COND_EXPR_ELSE (stmt
));
3996 GOTO_DESTINATION (stmt
) = label
;
4000 /* No non-abnormal edges should lead from a non-simple goto, and
4001 simple ones should be represented implicitly. */
4006 tree vec
= SWITCH_LABELS (stmt
);
4007 size_t i
, n
= TREE_VEC_LENGTH (vec
);
4009 for (i
= 0; i
< n
; ++i
)
4011 tree elt
= TREE_VEC_ELT (vec
, i
);
4012 if (label_to_block (CASE_LABEL (elt
)) == e
->dest
)
4013 CASE_LABEL (elt
) = label
;
4020 e
->flags
|= EDGE_FALLTHRU
;
4024 /* Otherwise it must be a fallthru edge, and we don't need to
4025 do anything besides redirecting it. */
4026 if (!(e
->flags
& EDGE_FALLTHRU
))
4031 /* Update/insert PHI nodes as necessary. */
4033 /* Now update the edges in the CFG. */
4034 e
= ssa_redirect_edge (e
, dest
);
4040 /* Simple wrapper, as we can always redirect fallthru edges. */
4043 tree_redirect_edge_and_branch_force (edge e
, basic_block dest
)
4045 e
= tree_redirect_edge_and_branch (e
, dest
);
4053 /* Splits basic block BB after statement STMT (but at least after the
4054 labels). If STMT is NULL, BB is split just after the labels. */
4057 tree_split_block (basic_block bb
, void *stmt
)
4059 block_stmt_iterator bsi
, bsi_tgt
;
4064 new_bb
= create_empty_bb (bb
);
4066 /* Redirect the outgoing edges. */
4067 new_bb
->succ
= bb
->succ
;
4069 for (e
= new_bb
->succ
; e
; e
= e
->succ_next
)
4072 if (stmt
&& TREE_CODE ((tree
) stmt
) == LABEL_EXPR
)
4075 /* Move everything from BSI to the new basic block. */
4076 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
4078 act
= bsi_stmt (bsi
);
4079 if (TREE_CODE (act
) == LABEL_EXPR
)
4092 bsi_tgt
= bsi_start (new_bb
);
4093 while (!bsi_end_p (bsi
))
4095 act
= bsi_stmt (bsi
);
4097 bsi_insert_after (&bsi_tgt
, act
, BSI_NEW_STMT
);
4104 /* Moves basic block BB after block AFTER. */
4107 tree_move_block_after (basic_block bb
, basic_block after
)
4109 if (bb
->prev_bb
== after
)
4113 link_block (bb
, after
);
4119 /* Return true if basic_block can be duplicated. */
4122 tree_can_duplicate_bb_p (basic_block bb ATTRIBUTE_UNUSED
)
4128 /* Create a duplicate of the basic block BB. NOTE: This does not
4129 preserve SSA form. */
4132 tree_duplicate_bb (basic_block bb
)
4135 block_stmt_iterator bsi
, bsi_tgt
;
4137 new_bb
= create_empty_bb (EXIT_BLOCK_PTR
->prev_bb
);
4138 bsi_tgt
= bsi_start (new_bb
);
4139 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
4141 tree stmt
= bsi_stmt (bsi
);
4143 if (TREE_CODE (stmt
) == LABEL_EXPR
)
4146 bsi_insert_after (&bsi_tgt
, unshare_expr (stmt
), BSI_NEW_STMT
);
4153 /* Dump FUNCTION_DECL FN to file FILE using FLAGS (see TDF_* in tree.h) */
4156 dump_function_to_file (tree fn
, FILE *file
, int flags
)
4158 tree arg
, vars
, var
;
4159 bool ignore_topmost_bind
= false, any_var
= false;
4163 fprintf (file
, "%s (", lang_hooks
.decl_printable_name (fn
, 2));
4165 arg
= DECL_ARGUMENTS (fn
);
4168 print_generic_expr (file
, arg
, dump_flags
);
4169 if (TREE_CHAIN (arg
))
4170 fprintf (file
, ", ");
4171 arg
= TREE_CHAIN (arg
);
4173 fprintf (file
, ")\n");
4175 if (flags
& TDF_RAW
)
4177 dump_node (fn
, TDF_SLIM
| flags
, file
);
4181 /* When GIMPLE is lowered, the variables are no longer available in
4182 BIND_EXPRs, so display them separately. */
4183 if (cfun
&& cfun
->unexpanded_var_list
)
4185 ignore_topmost_bind
= true;
4187 fprintf (file
, "{\n");
4188 for (vars
= cfun
->unexpanded_var_list
; vars
; vars
= TREE_CHAIN (vars
))
4190 var
= TREE_VALUE (vars
);
4192 print_generic_decl (file
, var
, flags
);
4193 fprintf (file
, "\n");
4199 if (basic_block_info
)
4201 /* Make a CFG based dump. */
4202 if (!ignore_topmost_bind
)
4203 fprintf (file
, "{\n");
4205 if (any_var
&& n_basic_blocks
)
4206 fprintf (file
, "\n");
4209 dump_generic_bb (file
, bb
, 2, flags
);
4211 fprintf (file
, "}\n");
4217 /* Make a tree based dump. */
4218 chain
= DECL_SAVED_TREE (fn
);
4220 if (TREE_CODE (chain
) == BIND_EXPR
)
4222 if (ignore_topmost_bind
)
4224 chain
= BIND_EXPR_BODY (chain
);
4232 if (!ignore_topmost_bind
)
4233 fprintf (file
, "{\n");
4238 fprintf (file
, "\n");
4240 print_generic_stmt_indented (file
, chain
, flags
, indent
);
4241 if (ignore_topmost_bind
)
4242 fprintf (file
, "}\n");
4245 fprintf (file
, "\n\n");
4249 /* Pretty print of the loops intermediate representation. */
4250 static void print_loop (FILE *, struct loop
*, int);
4251 static void print_pred_bbs (FILE *, edge
);
4252 static void print_succ_bbs (FILE *, edge
);
4255 /* Print the predecessors indexes of edge E on FILE. */
4258 print_pred_bbs (FILE *file
, edge e
)
4263 else if (e
->pred_next
== NULL
)
4264 fprintf (file
, "bb_%d", e
->src
->index
);
4268 fprintf (file
, "bb_%d, ", e
->src
->index
);
4269 print_pred_bbs (file
, e
->pred_next
);
4274 /* Print the successors indexes of edge E on FILE. */
4277 print_succ_bbs (FILE *file
, edge e
)
4281 else if (e
->succ_next
== NULL
)
4282 fprintf (file
, "bb_%d", e
->dest
->index
);
4285 fprintf (file
, "bb_%d, ", e
->dest
->index
);
4286 print_succ_bbs (file
, e
->succ_next
);
4291 /* Pretty print LOOP on FILE, indented INDENT spaces. */
4294 print_loop (FILE *file
, struct loop
*loop
, int indent
)
4302 s_indent
= (char *) alloca ((size_t) indent
+ 1);
4303 memset ((void *) s_indent
, ' ', (size_t) indent
);
4304 s_indent
[indent
] = '\0';
4306 /* Print the loop's header. */
4307 fprintf (file
, "%sloop_%d\n", s_indent
, loop
->num
);
4309 /* Print the loop's body. */
4310 fprintf (file
, "%s{\n", s_indent
);
4312 if (bb
->loop_father
== loop
)
4314 /* Print the basic_block's header. */
4315 fprintf (file
, "%s bb_%d (preds = {", s_indent
, bb
->index
);
4316 print_pred_bbs (file
, bb
->pred
);
4317 fprintf (file
, "}, succs = {");
4318 print_succ_bbs (file
, bb
->succ
);
4319 fprintf (file
, "})\n");
4321 /* Print the basic_block's body. */
4322 fprintf (file
, "%s {\n", s_indent
);
4323 tree_dump_bb (bb
, file
, indent
+ 4);
4324 fprintf (file
, "%s }\n", s_indent
);
4327 print_loop (file
, loop
->inner
, indent
+ 2);
4328 fprintf (file
, "%s}\n", s_indent
);
4329 print_loop (file
, loop
->next
, indent
);
4333 /* Follow a CFG edge from the entry point of the program, and on entry
4334 of a loop, pretty print the loop structure on FILE. */
4337 print_loop_ir (FILE *file
)
4341 bb
= BASIC_BLOCK (0);
4342 if (bb
&& bb
->loop_father
)
4343 print_loop (file
, bb
->loop_father
, 0);
4347 /* Debugging loops structure at tree level. */
4350 debug_loop_ir (void)
4352 print_loop_ir (stderr
);
4356 /* Return true if BB ends with a call, possibly followed by some
4357 instructions that must stay with the call. Return false,
4361 tree_block_ends_with_call_p (basic_block bb
)
4363 block_stmt_iterator bsi
= bsi_last (bb
);
4364 tree t
= tsi_stmt (bsi
.tsi
);
4366 if (TREE_CODE (t
) == RETURN_EXPR
&& TREE_OPERAND (t
, 0))
4367 t
= TREE_OPERAND (t
, 0);
4369 if (TREE_CODE (t
) == MODIFY_EXPR
)
4370 t
= TREE_OPERAND (t
, 1);
4372 return TREE_CODE (t
) == CALL_EXPR
;
4376 /* Return true if BB ends with a conditional branch. Return false,
4380 tree_block_ends_with_condjump_p (basic_block bb
)
4382 tree stmt
= tsi_stmt (bsi_last (bb
).tsi
);
4383 return (TREE_CODE (stmt
) == COND_EXPR
);
4387 /* Return true if we need to add fake edge to exit at statement T.
4388 Helper function for tree_flow_call_edges_add. */
4391 need_fake_edge_p (tree t
)
4393 if (TREE_CODE (t
) == RETURN_EXPR
&& TREE_OPERAND (t
, 0))
4394 t
= TREE_OPERAND (t
, 0);
4396 if (TREE_CODE (t
) == MODIFY_EXPR
)
4397 t
= TREE_OPERAND (t
, 1);
4399 /* NORETURN and LONGJMP calls already have an edge to exit.
4400 CONST, PURE and ALWAYS_RETURN calls do not need one.
4401 We don't currently check for CONST and PURE here, although
4402 it would be a good idea, because those attributes are
4403 figured out from the RTL in mark_constant_function, and
4404 the counter incrementation code from -fprofile-arcs
4405 leads to different results from -fbranch-probabilities. */
4406 if (TREE_CODE (t
) == CALL_EXPR
4407 && !(call_expr_flags (t
) &
4408 (ECF_NORETURN
| ECF_LONGJMP
| ECF_ALWAYS_RETURN
)))
4411 if (TREE_CODE (t
) == ASM_EXPR
4412 && (ASM_VOLATILE_P (t
) || ASM_INPUT_P (t
)))
4419 /* Add fake edges to the function exit for any non constant and non
4420 noreturn calls, volatile inline assembly in the bitmap of blocks
4421 specified by BLOCKS or to the whole CFG if BLOCKS is zero. Return
4422 the number of blocks that were split.
4424 The goal is to expose cases in which entering a basic block does
4425 not imply that all subsequent instructions must be executed. */
4428 tree_flow_call_edges_add (sbitmap blocks
)
4431 int blocks_split
= 0;
4432 int last_bb
= last_basic_block
;
4433 bool check_last_block
= false;
4435 if (n_basic_blocks
== 0)
4439 check_last_block
= true;
4441 check_last_block
= TEST_BIT (blocks
, EXIT_BLOCK_PTR
->prev_bb
->index
);
4443 /* In the last basic block, before epilogue generation, there will be
4444 a fallthru edge to EXIT. Special care is required if the last insn
4445 of the last basic block is a call because make_edge folds duplicate
4446 edges, which would result in the fallthru edge also being marked
4447 fake, which would result in the fallthru edge being removed by
4448 remove_fake_edges, which would result in an invalid CFG.
4450 Moreover, we can't elide the outgoing fake edge, since the block
4451 profiler needs to take this into account in order to solve the minimal
4452 spanning tree in the case that the call doesn't return.
4454 Handle this by adding a dummy instruction in a new last basic block. */
4455 if (check_last_block
)
4457 basic_block bb
= EXIT_BLOCK_PTR
->prev_bb
;
4458 block_stmt_iterator bsi
= bsi_last (bb
);
4460 if (!bsi_end_p (bsi
))
4463 if (need_fake_edge_p (t
))
4467 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
4468 if (e
->dest
== EXIT_BLOCK_PTR
)
4470 bsi_insert_on_edge (e
, build_empty_stmt ());
4471 bsi_commit_edge_inserts ((int *)NULL
);
4477 /* Now add fake edges to the function exit for any non constant
4478 calls since there is no way that we can determine if they will
4480 for (i
= 0; i
< last_bb
; i
++)
4482 basic_block bb
= BASIC_BLOCK (i
);
4483 block_stmt_iterator bsi
;
4484 tree stmt
, last_stmt
;
4489 if (blocks
&& !TEST_BIT (blocks
, i
))
4492 bsi
= bsi_last (bb
);
4493 if (!bsi_end_p (bsi
))
4495 last_stmt
= bsi_stmt (bsi
);
4498 stmt
= bsi_stmt (bsi
);
4499 if (need_fake_edge_p (stmt
))
4502 /* The handling above of the final block before the
4503 epilogue should be enough to verify that there is
4504 no edge to the exit block in CFG already.
4505 Calling make_edge in such case would cause us to
4506 mark that edge as fake and remove it later. */
4507 #ifdef ENABLE_CHECKING
4508 if (stmt
== last_stmt
)
4509 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
4510 if (e
->dest
== EXIT_BLOCK_PTR
)
4514 /* Note that the following may create a new basic block
4515 and renumber the existing basic blocks. */
4516 if (stmt
!= last_stmt
)
4518 e
= split_block (bb
, stmt
);
4522 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
4526 while (!bsi_end_p (bsi
));
4531 verify_flow_info ();
4533 return blocks_split
;
4537 struct cfg_hooks tree_cfg_hooks
= {
4539 tree_verify_flow_info
,
4540 tree_dump_bb
, /* dump_bb */
4541 create_bb
, /* create_basic_block */
4542 tree_redirect_edge_and_branch
,/* redirect_edge_and_branch */
4543 tree_redirect_edge_and_branch_force
,/* redirect_edge_and_branch_force */
4544 remove_bb
, /* delete_basic_block */
4545 tree_split_block
, /* split_block */
4546 tree_move_block_after
, /* move_block_after */
4547 tree_can_merge_blocks_p
, /* can_merge_blocks_p */
4548 tree_merge_blocks
, /* merge_blocks */
4549 tree_predict_edge
, /* predict_edge */
4550 tree_predicted_by_p
, /* predicted_by_p */
4551 tree_can_duplicate_bb_p
, /* can_duplicate_block_p */
4552 tree_duplicate_bb
, /* duplicate_block */
4553 tree_split_edge
, /* split_edge */
4554 tree_make_forwarder_block
, /* make_forward_block */
4555 NULL
, /* tidy_fallthru_edge */
4556 tree_block_ends_with_call_p
, /* block_ends_with_call_p */
4557 tree_block_ends_with_condjump_p
, /* block_ends_with_condjump_p */
4558 tree_flow_call_edges_add
/* flow_call_edges_add */
4562 /* Split all critical edges. */
4565 split_critical_edges (void)
4572 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
4573 if (EDGE_CRITICAL_P (e
) && !(e
->flags
& EDGE_ABNORMAL
))
4580 struct tree_opt_pass pass_split_crit_edges
=
4584 split_critical_edges
, /* execute */
4587 0, /* static_pass_number */
4588 TV_TREE_SPLIT_EDGES
, /* tv_id */
4589 PROP_cfg
, /* properties required */
4590 PROP_no_crit_edges
, /* properties_provided */
4591 0, /* properties_destroyed */
4592 0, /* todo_flags_start */
4593 0, /* todo_flags_finish */
4596 /* Emit return warnings. */
4599 execute_warn_function_return (void)
4605 if (warn_missing_noreturn
4606 && !TREE_THIS_VOLATILE (cfun
->decl
)
4607 && EXIT_BLOCK_PTR
->pred
== NULL
4608 && !lang_hooks
.function
.missing_noreturn_ok_p (cfun
->decl
))
4609 warning ("%Jfunction might be possible candidate for attribute `noreturn'",
4612 /* If we have a path to EXIT, then we do return. */
4613 if (TREE_THIS_VOLATILE (cfun
->decl
)
4614 && EXIT_BLOCK_PTR
->pred
!= NULL
)
4617 for (e
= EXIT_BLOCK_PTR
->pred
; e
; e
= e
->pred_next
)
4619 last
= last_stmt (e
->src
);
4620 if (TREE_CODE (last
) == RETURN_EXPR
4621 && (locus
= EXPR_LOCUS (last
)) != NULL
)
4625 locus
= &cfun
->function_end_locus
;
4626 warning ("%H`noreturn' function does return", locus
);
4629 /* If we see "return;" in some basic block, then we do reach the end
4630 without returning a value. */
4631 else if (warn_return_type
4632 && EXIT_BLOCK_PTR
->pred
!= NULL
4633 && !VOID_TYPE_P (TREE_TYPE (TREE_TYPE (cfun
->decl
))))
4635 for (e
= EXIT_BLOCK_PTR
->pred
; e
; e
= e
->pred_next
)
4637 tree last
= last_stmt (e
->src
);
4638 if (TREE_CODE (last
) == RETURN_EXPR
4639 && TREE_OPERAND (last
, 0) == NULL
)
4641 locus
= EXPR_LOCUS (last
);
4643 locus
= &cfun
->function_end_locus
;
4644 warning ("%Hcontrol reaches end of non-void function", locus
);
4652 /* Given a basic block B which ends with a conditional and has
4653 precisely two successors, determine which of the edges is taken if
4654 the conditional is true and which is taken if the conditional is
4655 false. Set TRUE_EDGE and FALSE_EDGE appropriately. */
4658 extract_true_false_edges_from_block (basic_block b
,
4664 if (e
->flags
& EDGE_TRUE_VALUE
)
4667 *false_edge
= e
->succ_next
;
4672 *true_edge
= e
->succ_next
;
4676 struct tree_opt_pass pass_warn_function_return
=
4680 execute_warn_function_return
, /* execute */
4683 0, /* static_pass_number */
4685 PROP_ssa
, /* properties_required */
4686 0, /* properties_provided */
4687 0, /* properties_destroyed */
4688 0, /* todo_flags_start */
4689 0 /* todo_flags_finish */
4692 #include "gt-tree-cfg.h"