1 /* Control flow functions for trees.
2 Copyright (C) 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
3 Contributed by Diego Novillo <dnovillo@redhat.com>
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 GCC is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to
19 the Free Software Foundation, 59 Temple Place - Suite 330,
20 Boston, MA 02111-1307, USA. */
24 #include "coretypes.h"
29 #include "hard-reg-set.h"
30 #include "basic-block.h"
37 #include "langhooks.h"
38 #include "diagnostic.h"
39 #include "tree-flow.h"
41 #include "tree-dump.h"
42 #include "tree-pass.h"
47 /* This file contains functions for building the Control Flow Graph (CFG)
48 for a function tree. */
50 /* Local declarations. */
52 /* Initial capacity for the basic block array. */
53 static const int initial_cfg_capacity
= 20;
55 /* Mapping of labels to their associated blocks. This can greatly speed up
56 building of the CFG in code with lots of gotos. */
57 static GTY(()) varray_type label_to_block_map
;
62 long num_merged_labels
;
65 static struct cfg_stats_d cfg_stats
;
67 /* Nonzero if we found a computed goto while building basic blocks. */
68 static bool found_computed_goto
;
70 /* Basic blocks and flowgraphs. */
71 static basic_block
create_bb (void *, void *, basic_block
);
72 static void create_block_annotation (basic_block
);
73 static void free_blocks_annotations (void);
74 static void clear_blocks_annotations (void);
75 static void make_blocks (tree
);
76 static void factor_computed_gotos (void);
79 static void make_edges (void);
80 static void make_ctrl_stmt_edges (basic_block
);
81 static void make_exit_edges (basic_block
);
82 static void make_cond_expr_edges (basic_block
);
83 static void make_switch_expr_edges (basic_block
);
84 static void make_goto_expr_edges (basic_block
);
85 static edge
tree_redirect_edge_and_branch (edge
, basic_block
);
86 static edge
tree_try_redirect_by_replacing_jump (edge
, basic_block
);
87 static void split_critical_edges (void);
89 /* Various helpers. */
90 static inline bool stmt_starts_bb_p (tree
, tree
);
91 static int tree_verify_flow_info (void);
92 static void tree_make_forwarder_block (edge
);
93 static bool thread_jumps (void);
94 static bool tree_forwarder_block_p (basic_block
);
95 static void bsi_commit_edge_inserts_1 (edge e
);
96 static void tree_cfg2vcg (FILE *);
98 /* Flowgraph optimization and cleanup. */
99 static void tree_merge_blocks (basic_block
, basic_block
);
100 static bool tree_can_merge_blocks_p (basic_block
, basic_block
);
101 static void remove_bb (basic_block
);
102 static bool cleanup_control_flow (void);
103 static bool cleanup_control_expr_graph (basic_block
, block_stmt_iterator
);
104 static edge
find_taken_edge_cond_expr (basic_block
, tree
);
105 static edge
find_taken_edge_switch_expr (basic_block
, tree
);
106 static tree
find_case_label_for_value (tree
, tree
);
107 static bool phi_alternatives_equal (basic_block
, edge
, edge
);
110 /*---------------------------------------------------------------------------
112 ---------------------------------------------------------------------------*/
114 /* Entry point to the CFG builder for trees. TP points to the list of
115 statements to be added to the flowgraph. */
118 build_tree_cfg (tree
*tp
)
120 /* Register specific tree functions. */
121 tree_register_cfg_hooks ();
123 /* Initialize rbi_pool. */
126 /* Initialize the basic block array. */
128 profile_status
= PROFILE_ABSENT
;
130 last_basic_block
= 0;
131 VARRAY_BB_INIT (basic_block_info
, initial_cfg_capacity
, "basic_block_info");
132 memset ((void *) &cfg_stats
, 0, sizeof (cfg_stats
));
134 /* Build a mapping of labels to their associated blocks. */
135 VARRAY_BB_INIT (label_to_block_map
, initial_cfg_capacity
,
136 "label to block map");
138 ENTRY_BLOCK_PTR
->next_bb
= EXIT_BLOCK_PTR
;
139 EXIT_BLOCK_PTR
->prev_bb
= ENTRY_BLOCK_PTR
;
141 found_computed_goto
= 0;
144 /* Computed gotos are hell to deal with, especially if there are
145 lots of them with a large number of destinations. So we factor
146 them to a common computed goto location before we build the
147 edge list. After we convert back to normal form, we will un-factor
148 the computed gotos since factoring introduces an unwanted jump. */
149 if (found_computed_goto
)
150 factor_computed_gotos ();
152 /* Make sure there is always at least one block, even if its empty. */
153 if (n_basic_blocks
== 0)
154 create_empty_bb (ENTRY_BLOCK_PTR
);
156 create_block_annotation (ENTRY_BLOCK_PTR
);
157 create_block_annotation (EXIT_BLOCK_PTR
);
159 /* Adjust the size of the array. */
160 VARRAY_GROW (basic_block_info
, n_basic_blocks
);
162 /* To speed up statement iterator walks, we first purge dead labels. */
163 cleanup_dead_labels ();
165 /* Group case nodes to reduce the number of edges.
166 We do this after cleaning up dead labels because otherwise we miss
167 a lot of obvious case merging opportunities. */
168 group_case_labels ();
170 /* Create the edges of the flowgraph. */
173 /* Debugging dumps. */
175 /* Write the flowgraph to a VCG file. */
177 int local_dump_flags
;
178 FILE *dump_file
= dump_begin (TDI_vcg
, &local_dump_flags
);
181 tree_cfg2vcg (dump_file
);
182 dump_end (TDI_vcg
, dump_file
);
186 /* Dump a textual representation of the flowgraph. */
188 dump_tree_cfg (dump_file
, dump_flags
);
192 execute_build_cfg (void)
194 build_tree_cfg (&DECL_SAVED_TREE (current_function_decl
));
197 struct tree_opt_pass pass_build_cfg
=
201 execute_build_cfg
, /* execute */
204 0, /* static_pass_number */
205 TV_TREE_CFG
, /* tv_id */
206 PROP_gimple_leh
, /* properties_required */
207 PROP_cfg
, /* properties_provided */
208 0, /* properties_destroyed */
209 0, /* todo_flags_start */
210 TODO_verify_stmts
/* todo_flags_finish */
213 /* Search the CFG for any computed gotos. If found, factor them to a
214 common computed goto site. Also record the location of that site so
215 that we can un-factor the gotos after we have converted back to
219 factor_computed_gotos (void)
222 tree factored_label_decl
= NULL
;
224 tree factored_computed_goto_label
= NULL
;
225 tree factored_computed_goto
= NULL
;
227 /* We know there are one or more computed gotos in this function.
228 Examine the last statement in each basic block to see if the block
229 ends with a computed goto. */
233 block_stmt_iterator bsi
= bsi_last (bb
);
238 last
= bsi_stmt (bsi
);
240 /* Ignore the computed goto we create when we factor the original
242 if (last
== factored_computed_goto
)
245 /* If the last statement is a computed goto, factor it. */
246 if (computed_goto_p (last
))
250 /* The first time we find a computed goto we need to create
251 the factored goto block and the variable each original
252 computed goto will use for their goto destination. */
253 if (! factored_computed_goto
)
255 basic_block new_bb
= create_empty_bb (bb
);
256 block_stmt_iterator new_bsi
= bsi_start (new_bb
);
258 /* Create the destination of the factored goto. Each original
259 computed goto will put its desired destination into this
260 variable and jump to the label we create immediately
262 var
= create_tmp_var (ptr_type_node
, "gotovar");
264 /* Build a label for the new block which will contain the
265 factored computed goto. */
266 factored_label_decl
= create_artificial_label ();
267 factored_computed_goto_label
268 = build1 (LABEL_EXPR
, void_type_node
, factored_label_decl
);
269 bsi_insert_after (&new_bsi
, factored_computed_goto_label
,
272 /* Build our new computed goto. */
273 factored_computed_goto
= build1 (GOTO_EXPR
, void_type_node
, var
);
274 bsi_insert_after (&new_bsi
, factored_computed_goto
,
278 /* Copy the original computed goto's destination into VAR. */
279 assignment
= build (MODIFY_EXPR
, ptr_type_node
,
280 var
, GOTO_DESTINATION (last
));
281 bsi_insert_before (&bsi
, assignment
, BSI_SAME_STMT
);
283 /* And re-vector the computed goto to the new destination. */
284 GOTO_DESTINATION (last
) = factored_label_decl
;
290 /* Create annotations for a single basic block. */
293 create_block_annotation (basic_block bb
)
295 /* Verify that the tree_annotations field is clear. */
296 if (bb
->tree_annotations
)
298 bb
->tree_annotations
= ggc_alloc_cleared (sizeof (struct bb_ann_d
));
302 /* Free the annotations for all the basic blocks. */
304 static void free_blocks_annotations (void)
306 clear_blocks_annotations ();
310 /* Clear the annotations for all the basic blocks. */
313 clear_blocks_annotations (void)
317 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
, NULL
, next_bb
)
318 bb
->tree_annotations
= NULL
;
322 /* Build a flowgraph for the statement_list STMT_LIST. */
325 make_blocks (tree stmt_list
)
327 tree_stmt_iterator i
= tsi_start (stmt_list
);
329 bool start_new_block
= true;
330 bool first_stmt_of_list
= true;
331 basic_block bb
= ENTRY_BLOCK_PTR
;
333 while (!tsi_end_p (i
))
340 /* If the statement starts a new basic block or if we have determined
341 in a previous pass that we need to create a new block for STMT, do
343 if (start_new_block
|| stmt_starts_bb_p (stmt
, prev_stmt
))
345 if (!first_stmt_of_list
)
346 stmt_list
= tsi_split_statement_list_before (&i
);
347 bb
= create_basic_block (stmt_list
, NULL
, bb
);
348 start_new_block
= false;
351 /* Now add STMT to BB and create the subgraphs for special statement
353 set_bb_for_stmt (stmt
, bb
);
355 if (computed_goto_p (stmt
))
356 found_computed_goto
= true;
358 /* If STMT is a basic block terminator, set START_NEW_BLOCK for the
360 if (stmt_ends_bb_p (stmt
))
361 start_new_block
= true;
364 first_stmt_of_list
= false;
369 /* Create and return a new empty basic block after bb AFTER. */
372 create_bb (void *h
, void *e
, basic_block after
)
379 /* Create and initialize a new basic block. */
381 memset (bb
, 0, sizeof (*bb
));
383 bb
->index
= last_basic_block
;
385 bb
->stmt_list
= h
? h
: alloc_stmt_list ();
387 /* Add the new block to the linked list of blocks. */
388 link_block (bb
, after
);
390 /* Grow the basic block array if needed. */
391 if ((size_t) last_basic_block
== VARRAY_SIZE (basic_block_info
))
393 size_t new_size
= last_basic_block
+ (last_basic_block
+ 3) / 4;
394 VARRAY_GROW (basic_block_info
, new_size
);
397 /* Add the newly created block to the array. */
398 BASIC_BLOCK (last_basic_block
) = bb
;
400 create_block_annotation (bb
);
405 initialize_bb_rbi (bb
);
410 /*---------------------------------------------------------------------------
412 ---------------------------------------------------------------------------*/
414 /* Join all the blocks in the flowgraph. */
421 /* Create an edge from entry to the first block with executable
423 make_edge (ENTRY_BLOCK_PTR
, BASIC_BLOCK (0), EDGE_FALLTHRU
);
425 /* Traverse basic block array placing edges. */
428 tree first
= first_stmt (bb
);
429 tree last
= last_stmt (bb
);
433 /* Edges for statements that always alter flow control. */
434 if (is_ctrl_stmt (last
))
435 make_ctrl_stmt_edges (bb
);
437 /* Edges for statements that sometimes alter flow control. */
438 if (is_ctrl_altering_stmt (last
))
439 make_exit_edges (bb
);
442 /* Finally, if no edges were created above, this is a regular
443 basic block that only needs a fallthru edge. */
444 if (bb
->succ
== NULL
)
445 make_edge (bb
, bb
->next_bb
, EDGE_FALLTHRU
);
448 /* We do not care about fake edges, so remove any that the CFG
449 builder inserted for completeness. */
450 remove_fake_exit_edges ();
452 /* Clean up the graph and warn for unreachable code. */
457 /* Create edges for control statement at basic block BB. */
460 make_ctrl_stmt_edges (basic_block bb
)
462 tree last
= last_stmt (bb
);
464 #if defined ENABLE_CHECKING
465 if (last
== NULL_TREE
)
469 switch (TREE_CODE (last
))
472 make_goto_expr_edges (bb
);
476 make_edge (bb
, EXIT_BLOCK_PTR
, 0);
480 make_cond_expr_edges (bb
);
484 make_switch_expr_edges (bb
);
488 make_eh_edges (last
);
489 /* Yet another NORETURN hack. */
490 if (bb
->succ
== NULL
)
491 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
500 /* Create exit edges for statements in block BB that alter the flow of
501 control. Statements that alter the control flow are 'goto', 'return'
502 and calls to non-returning functions. */
505 make_exit_edges (basic_block bb
)
507 tree last
= last_stmt (bb
), op
;
509 if (last
== NULL_TREE
)
512 switch (TREE_CODE (last
))
515 /* If this function receives a nonlocal goto, then we need to
516 make edges from this call site to all the nonlocal goto
518 if (TREE_SIDE_EFFECTS (last
)
519 && current_function_has_nonlocal_label
)
520 make_goto_expr_edges (bb
);
522 /* If this statement has reachable exception handlers, then
523 create abnormal edges to them. */
524 make_eh_edges (last
);
526 /* Some calls are known not to return. For such calls we create
529 We really need to revamp how we build edges so that it's not
530 such a bloody pain to avoid creating edges for this case since
531 all we do is remove these edges when we're done building the
533 if (call_expr_flags (last
) & (ECF_NORETURN
| ECF_LONGJMP
))
535 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
539 /* Don't forget the fall-thru edge. */
540 make_edge (bb
, bb
->next_bb
, EDGE_FALLTHRU
);
544 /* A MODIFY_EXPR may have a CALL_EXPR on its RHS and the CALL_EXPR
545 may have an abnormal edge. Search the RHS for this case and
546 create any required edges. */
547 op
= get_call_expr_in (last
);
548 if (op
&& TREE_SIDE_EFFECTS (op
)
549 && current_function_has_nonlocal_label
)
550 make_goto_expr_edges (bb
);
552 make_eh_edges (last
);
553 make_edge (bb
, bb
->next_bb
, EDGE_FALLTHRU
);
562 /* Create the edges for a COND_EXPR starting at block BB.
563 At this point, both clauses must contain only simple gotos. */
566 make_cond_expr_edges (basic_block bb
)
568 tree entry
= last_stmt (bb
);
569 basic_block then_bb
, else_bb
;
570 tree then_label
, else_label
;
572 #if defined ENABLE_CHECKING
573 if (entry
== NULL_TREE
|| TREE_CODE (entry
) != COND_EXPR
)
577 /* Entry basic blocks for each component. */
578 then_label
= GOTO_DESTINATION (COND_EXPR_THEN (entry
));
579 else_label
= GOTO_DESTINATION (COND_EXPR_ELSE (entry
));
580 then_bb
= label_to_block (then_label
);
581 else_bb
= label_to_block (else_label
);
583 make_edge (bb
, then_bb
, EDGE_TRUE_VALUE
);
584 make_edge (bb
, else_bb
, EDGE_FALSE_VALUE
);
588 /* Create the edges for a SWITCH_EXPR starting at block BB.
589 At this point, the switch body has been lowered and the
590 SWITCH_LABELS filled in, so this is in effect a multi-way branch. */
593 make_switch_expr_edges (basic_block bb
)
595 tree entry
= last_stmt (bb
);
599 vec
= SWITCH_LABELS (entry
);
600 n
= TREE_VEC_LENGTH (vec
);
602 for (i
= 0; i
< n
; ++i
)
604 tree lab
= CASE_LABEL (TREE_VEC_ELT (vec
, i
));
605 basic_block label_bb
= label_to_block (lab
);
606 make_edge (bb
, label_bb
, 0);
611 /* Return the basic block holding label DEST. */
614 label_to_block (tree dest
)
616 int uid
= LABEL_DECL_UID (dest
);
618 /* We would die hard when faced by undefined label. Emit label to
619 very first basic block. This will hopefully make even the dataflow
620 and undefined variable warnings quite right. */
621 if ((errorcount
|| sorrycount
) && uid
< 0)
623 block_stmt_iterator bsi
= bsi_start (BASIC_BLOCK (0));
626 stmt
= build1 (LABEL_EXPR
, void_type_node
, dest
);
627 bsi_insert_before (&bsi
, stmt
, BSI_NEW_STMT
);
628 uid
= LABEL_DECL_UID (dest
);
630 return VARRAY_BB (label_to_block_map
, uid
);
634 /* Create edges for a goto statement at block BB. */
637 make_goto_expr_edges (basic_block bb
)
640 basic_block target_bb
;
642 block_stmt_iterator last
= bsi_last (bb
);
644 goto_t
= bsi_stmt (last
);
646 /* If the last statement is not a GOTO (i.e., it is a RETURN_EXPR,
647 CALL_EXPR or MODIFY_EXPR), then the edge is an abnormal edge resulting
648 from a nonlocal goto. */
649 if (TREE_CODE (goto_t
) != GOTO_EXPR
)
651 dest
= error_mark_node
;
656 dest
= GOTO_DESTINATION (goto_t
);
659 /* A GOTO to a local label creates normal edges. */
660 if (simple_goto_p (goto_t
))
662 edge e
= make_edge (bb
, label_to_block (dest
), EDGE_FALLTHRU
);
663 #ifdef USE_MAPPED_LOCATION
664 e
->goto_locus
= EXPR_LOCATION (goto_t
);
666 e
->goto_locus
= EXPR_LOCUS (goto_t
);
672 /* Nothing more to do for nonlocal gotos. */
673 if (TREE_CODE (dest
) == LABEL_DECL
)
676 /* Computed gotos remain. */
679 /* Look for the block starting with the destination label. In the
680 case of a computed goto, make an edge to any label block we find
682 FOR_EACH_BB (target_bb
)
684 block_stmt_iterator bsi
;
686 for (bsi
= bsi_start (target_bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
688 tree target
= bsi_stmt (bsi
);
690 if (TREE_CODE (target
) != LABEL_EXPR
)
694 /* Computed GOTOs. Make an edge to every label block that has
695 been marked as a potential target for a computed goto. */
696 (FORCED_LABEL (LABEL_EXPR_LABEL (target
)) && for_call
== 0)
697 /* Nonlocal GOTO target. Make an edge to every label block
698 that has been marked as a potential target for a nonlocal
700 || (DECL_NONLOCAL (LABEL_EXPR_LABEL (target
)) && for_call
== 1))
702 make_edge (bb
, target_bb
, EDGE_ABNORMAL
);
708 /* Degenerate case of computed goto with no labels. */
709 if (!for_call
&& !bb
->succ
)
710 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
714 /*---------------------------------------------------------------------------
716 ---------------------------------------------------------------------------*/
718 /* Remove unreachable blocks and other miscellaneous clean up work. */
721 cleanup_tree_cfg (void)
723 bool something_changed
= true;
726 timevar_push (TV_TREE_CLEANUP_CFG
);
728 /* These three transformations can cascade, so we iterate on them until
730 while (something_changed
)
732 something_changed
= cleanup_control_flow ();
733 something_changed
|= delete_unreachable_blocks ();
734 something_changed
|= thread_jumps ();
735 retval
|= something_changed
;
738 /* Merging the blocks creates no new opportunities for the other
739 optimizations, so do it here. */
744 #ifdef ENABLE_CHECKING
747 timevar_pop (TV_TREE_CLEANUP_CFG
);
752 /* Cleanup useless labels in basic blocks. This is something we wish
753 to do early because it allows us to group case labels before creating
754 the edges for the CFG, and it speeds up block statement iterators in
756 We only run this pass once, running it more than once is probably not
759 /* A map from basic block index to the leading label of that block. */
760 static tree
*label_for_bb
;
762 /* Callback for for_each_eh_region. Helper for cleanup_dead_labels. */
764 update_eh_label (struct eh_region
*region
)
766 tree old_label
= get_eh_region_tree_label (region
);
770 basic_block bb
= label_to_block (old_label
);
772 /* ??? After optimizing, there may be EH regions with labels
773 that have already been removed from the function body, so
774 there is no basic block for them. */
778 new_label
= label_for_bb
[bb
->index
];
779 set_eh_region_tree_label (region
, new_label
);
783 /* Given LABEL return the first label in the same basic block. */
785 main_block_label (tree label
)
787 basic_block bb
= label_to_block (label
);
789 /* label_to_block possibly inserted undefined label into the chain. */
790 if (!label_for_bb
[bb
->index
])
791 label_for_bb
[bb
->index
] = label
;
792 return label_for_bb
[bb
->index
];
795 /* Cleanup redundant labels. This is a three-steo process:
796 1) Find the leading label for each block.
797 2) Redirect all references to labels to the leading labels.
798 3) Cleanup all useless labels. */
801 cleanup_dead_labels (void)
804 label_for_bb
= xcalloc (last_basic_block
, sizeof (tree
));
806 /* Find a suitable label for each block. We use the first user-defined
807 label is there is one, or otherwise just the first label we see. */
810 block_stmt_iterator i
;
812 for (i
= bsi_start (bb
); !bsi_end_p (i
); bsi_next (&i
))
814 tree label
, stmt
= bsi_stmt (i
);
816 if (TREE_CODE (stmt
) != LABEL_EXPR
)
819 label
= LABEL_EXPR_LABEL (stmt
);
821 /* If we have not yet seen a label for the current block,
822 remember this one and see if there are more labels. */
823 if (! label_for_bb
[bb
->index
])
825 label_for_bb
[bb
->index
] = label
;
829 /* If we did see a label for the current block already, but it
830 is an artificially created label, replace it if the current
831 label is a user defined label. */
832 if (! DECL_ARTIFICIAL (label
)
833 && DECL_ARTIFICIAL (label_for_bb
[bb
->index
]))
835 label_for_bb
[bb
->index
] = label
;
841 /* Now redirect all jumps/branches to the selected label.
842 First do so for each block ending in a control statement. */
845 tree stmt
= last_stmt (bb
);
849 switch (TREE_CODE (stmt
))
853 tree true_branch
, false_branch
;
855 true_branch
= COND_EXPR_THEN (stmt
);
856 false_branch
= COND_EXPR_ELSE (stmt
);
858 GOTO_DESTINATION (true_branch
)
859 = main_block_label (GOTO_DESTINATION (true_branch
));
860 GOTO_DESTINATION (false_branch
)
861 = main_block_label (GOTO_DESTINATION (false_branch
));
869 tree vec
= SWITCH_LABELS (stmt
);
870 size_t n
= TREE_VEC_LENGTH (vec
);
872 /* Replace all destination labels. */
873 for (i
= 0; i
< n
; ++i
)
874 CASE_LABEL (TREE_VEC_ELT (vec
, i
))
875 = main_block_label (CASE_LABEL (TREE_VEC_ELT (vec
, i
)));
880 /* We have to handle GOTO_EXPRs until they're removed, and we don't
881 remove them until after we've created the CFG edges. */
883 if (! computed_goto_p (stmt
))
885 GOTO_DESTINATION (stmt
)
886 = main_block_label (GOTO_DESTINATION (stmt
));
895 for_each_eh_region (update_eh_label
);
897 /* Finally, purge dead labels. All user-defined labels and labels that
898 can be the target of non-local gotos are preserved. */
901 block_stmt_iterator i
;
902 tree label_for_this_bb
= label_for_bb
[bb
->index
];
904 if (! label_for_this_bb
)
907 for (i
= bsi_start (bb
); !bsi_end_p (i
); )
909 tree label
, stmt
= bsi_stmt (i
);
911 if (TREE_CODE (stmt
) != LABEL_EXPR
)
914 label
= LABEL_EXPR_LABEL (stmt
);
916 if (label
== label_for_this_bb
917 || ! DECL_ARTIFICIAL (label
)
918 || DECL_NONLOCAL (label
))
928 /* Look for blocks ending in a multiway branch (a SWITCH_EXPR in GIMPLE),
929 and scan the sorted vector of cases. Combine the ones jumping to the
931 Eg. three separate entries 1: 2: 3: become one entry 1..3: */
934 group_case_labels (void)
940 tree stmt
= last_stmt (bb
);
941 if (stmt
&& TREE_CODE (stmt
) == SWITCH_EXPR
)
943 tree labels
= SWITCH_LABELS (stmt
);
944 int old_size
= TREE_VEC_LENGTH (labels
);
945 int i
, j
, new_size
= old_size
;
946 tree default_label
= TREE_VEC_ELT (labels
, old_size
- 1);
948 /* Look for possible opportunities to merge cases.
949 Ignore the last element of the label vector because it
950 must be the default case. */
952 while (i
< old_size
- 2)
954 tree base_case
, base_label
, base_high
, type
;
955 base_case
= TREE_VEC_ELT (labels
, i
);
960 base_label
= CASE_LABEL (base_case
);
962 /* Discard cases that have the same destination as the
964 if (base_label
== default_label
)
966 TREE_VEC_ELT (labels
, i
) = NULL_TREE
;
971 type
= TREE_TYPE (CASE_LOW (base_case
));
972 base_high
= CASE_HIGH (base_case
) ?
973 CASE_HIGH (base_case
) : CASE_LOW (base_case
);
975 /* Try to merge case labels. Break out when we reach the end
976 of the label vector or when we cannot merge the next case
977 label with the current one. */
978 while (i
< old_size
- 2)
980 tree merge_case
= TREE_VEC_ELT (labels
, ++i
);
981 tree merge_label
= CASE_LABEL (merge_case
);
982 tree t
= int_const_binop (PLUS_EXPR
, base_high
,
983 integer_one_node
, 1);
985 /* Merge the cases if they jump to the same place,
986 and their ranges are consecutive. */
987 if (merge_label
== base_label
988 && tree_int_cst_equal (CASE_LOW (merge_case
), t
))
990 base_high
= CASE_HIGH (merge_case
) ?
991 CASE_HIGH (merge_case
) : CASE_LOW (merge_case
);
992 CASE_HIGH (base_case
) = base_high
;
993 TREE_VEC_ELT (labels
, i
) = NULL_TREE
;
1001 /* Compress the case labels in the label vector, and adjust the
1002 length of the vector. */
1003 for (i
= 0, j
= 0; i
< new_size
; i
++)
1005 while (! TREE_VEC_ELT (labels
, j
))
1007 TREE_VEC_ELT (labels
, i
) = TREE_VEC_ELT (labels
, j
++);
1009 TREE_VEC_LENGTH (labels
) = new_size
;
1014 /* Checks whether we can merge block B into block A. */
1017 tree_can_merge_blocks_p (basic_block a
, basic_block b
)
1020 block_stmt_iterator bsi
;
1023 || a
->succ
->succ_next
)
1026 if (a
->succ
->flags
& EDGE_ABNORMAL
)
1029 if (a
->succ
->dest
!= b
)
1032 if (b
== EXIT_BLOCK_PTR
)
1035 if (b
->pred
->pred_next
)
1038 /* If A ends by a statement causing exceptions or something similar, we
1039 cannot merge the blocks. */
1040 stmt
= last_stmt (a
);
1041 if (stmt
&& stmt_ends_bb_p (stmt
))
1044 /* Do not allow a block with only a non-local label to be merged. */
1045 if (stmt
&& TREE_CODE (stmt
) == LABEL_EXPR
1046 && DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt
)))
1049 /* There may be no phi nodes at the start of b. Most of these degenerate
1050 phi nodes should be cleaned up by kill_redundant_phi_nodes. */
1054 /* Do not remove user labels. */
1055 for (bsi
= bsi_start (b
); !bsi_end_p (bsi
); bsi_next (&bsi
))
1057 stmt
= bsi_stmt (bsi
);
1058 if (TREE_CODE (stmt
) != LABEL_EXPR
)
1060 if (!DECL_ARTIFICIAL (LABEL_EXPR_LABEL (stmt
)))
1068 /* Merge block B into block A. */
1071 tree_merge_blocks (basic_block a
, basic_block b
)
1073 block_stmt_iterator bsi
;
1074 tree_stmt_iterator last
;
1077 fprintf (dump_file
, "Merging blocks %d and %d\n", a
->index
, b
->index
);
1079 /* Ensure that B follows A. */
1080 move_block_after (b
, a
);
1082 if (!(a
->succ
->flags
& EDGE_FALLTHRU
))
1086 && stmt_ends_bb_p (last_stmt (a
)))
1089 /* Remove labels from B and set bb_for_stmt to A for other statements. */
1090 for (bsi
= bsi_start (b
); !bsi_end_p (bsi
);)
1092 if (TREE_CODE (bsi_stmt (bsi
)) == LABEL_EXPR
)
1096 set_bb_for_stmt (bsi_stmt (bsi
), a
);
1101 /* Merge the chains. */
1102 last
= tsi_last (a
->stmt_list
);
1103 tsi_link_after (&last
, b
->stmt_list
, TSI_NEW_STMT
);
1104 b
->stmt_list
= NULL
;
1108 /* Walk the function tree removing unnecessary statements.
1110 * Empty statement nodes are removed
1112 * Unnecessary TRY_FINALLY and TRY_CATCH blocks are removed
1114 * Unnecessary COND_EXPRs are removed
1116 * Some unnecessary BIND_EXPRs are removed
1118 Clearly more work could be done. The trick is doing the analysis
1119 and removal fast enough to be a net improvement in compile times.
1121 Note that when we remove a control structure such as a COND_EXPR
1122 BIND_EXPR, or TRY block, we will need to repeat this optimization pass
1123 to ensure we eliminate all the useless code. */
1134 static void remove_useless_stmts_1 (tree
*, struct rus_data
*);
1137 remove_useless_stmts_warn_notreached (tree stmt
)
1139 if (EXPR_HAS_LOCATION (stmt
))
1141 location_t loc
= EXPR_LOCATION (stmt
);
1142 warning ("%Hwill never be executed", &loc
);
1146 switch (TREE_CODE (stmt
))
1148 case STATEMENT_LIST
:
1150 tree_stmt_iterator i
;
1151 for (i
= tsi_start (stmt
); !tsi_end_p (i
); tsi_next (&i
))
1152 if (remove_useless_stmts_warn_notreached (tsi_stmt (i
)))
1158 if (remove_useless_stmts_warn_notreached (COND_EXPR_COND (stmt
)))
1160 if (remove_useless_stmts_warn_notreached (COND_EXPR_THEN (stmt
)))
1162 if (remove_useless_stmts_warn_notreached (COND_EXPR_ELSE (stmt
)))
1166 case TRY_FINALLY_EXPR
:
1167 case TRY_CATCH_EXPR
:
1168 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt
, 0)))
1170 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt
, 1)))
1175 return remove_useless_stmts_warn_notreached (CATCH_BODY (stmt
));
1176 case EH_FILTER_EXPR
:
1177 return remove_useless_stmts_warn_notreached (EH_FILTER_FAILURE (stmt
));
1179 return remove_useless_stmts_warn_notreached (BIND_EXPR_BLOCK (stmt
));
1182 /* Not a live container. */
1190 remove_useless_stmts_cond (tree
*stmt_p
, struct rus_data
*data
)
1192 tree then_clause
, else_clause
, cond
;
1193 bool save_has_label
, then_has_label
, else_has_label
;
1195 save_has_label
= data
->has_label
;
1196 data
->has_label
= false;
1197 data
->last_goto
= NULL
;
1199 remove_useless_stmts_1 (&COND_EXPR_THEN (*stmt_p
), data
);
1201 then_has_label
= data
->has_label
;
1202 data
->has_label
= false;
1203 data
->last_goto
= NULL
;
1205 remove_useless_stmts_1 (&COND_EXPR_ELSE (*stmt_p
), data
);
1207 else_has_label
= data
->has_label
;
1208 data
->has_label
= save_has_label
| then_has_label
| else_has_label
;
1211 then_clause
= COND_EXPR_THEN (*stmt_p
);
1212 else_clause
= COND_EXPR_ELSE (*stmt_p
);
1213 cond
= COND_EXPR_COND (*stmt_p
);
1215 /* If neither arm does anything at all, we can remove the whole IF. */
1216 if (!TREE_SIDE_EFFECTS (then_clause
) && !TREE_SIDE_EFFECTS (else_clause
))
1218 *stmt_p
= build_empty_stmt ();
1219 data
->repeat
= true;
1222 /* If there are no reachable statements in an arm, then we can
1223 zap the entire conditional. */
1224 else if (integer_nonzerop (cond
) && !else_has_label
)
1226 if (warn_notreached
)
1227 remove_useless_stmts_warn_notreached (else_clause
);
1228 *stmt_p
= then_clause
;
1229 data
->repeat
= true;
1231 else if (integer_zerop (cond
) && !then_has_label
)
1233 if (warn_notreached
)
1234 remove_useless_stmts_warn_notreached (then_clause
);
1235 *stmt_p
= else_clause
;
1236 data
->repeat
= true;
1239 /* Check a couple of simple things on then/else with single stmts. */
1242 tree then_stmt
= expr_only (then_clause
);
1243 tree else_stmt
= expr_only (else_clause
);
1245 /* Notice branches to a common destination. */
1246 if (then_stmt
&& else_stmt
1247 && TREE_CODE (then_stmt
) == GOTO_EXPR
1248 && TREE_CODE (else_stmt
) == GOTO_EXPR
1249 && (GOTO_DESTINATION (then_stmt
) == GOTO_DESTINATION (else_stmt
)))
1251 *stmt_p
= then_stmt
;
1252 data
->repeat
= true;
1255 /* If the THEN/ELSE clause merely assigns a value to a variable or
1256 parameter which is already known to contain that value, then
1257 remove the useless THEN/ELSE clause. */
1258 else if (TREE_CODE (cond
) == VAR_DECL
|| TREE_CODE (cond
) == PARM_DECL
)
1261 && TREE_CODE (else_stmt
) == MODIFY_EXPR
1262 && TREE_OPERAND (else_stmt
, 0) == cond
1263 && integer_zerop (TREE_OPERAND (else_stmt
, 1)))
1264 COND_EXPR_ELSE (*stmt_p
) = alloc_stmt_list ();
1266 else if ((TREE_CODE (cond
) == EQ_EXPR
|| TREE_CODE (cond
) == NE_EXPR
)
1267 && (TREE_CODE (TREE_OPERAND (cond
, 0)) == VAR_DECL
1268 || TREE_CODE (TREE_OPERAND (cond
, 0)) == PARM_DECL
)
1269 && TREE_CONSTANT (TREE_OPERAND (cond
, 1)))
1271 tree stmt
= (TREE_CODE (cond
) == EQ_EXPR
1272 ? then_stmt
: else_stmt
);
1273 tree
*location
= (TREE_CODE (cond
) == EQ_EXPR
1274 ? &COND_EXPR_THEN (*stmt_p
)
1275 : &COND_EXPR_ELSE (*stmt_p
));
1278 && TREE_CODE (stmt
) == MODIFY_EXPR
1279 && TREE_OPERAND (stmt
, 0) == TREE_OPERAND (cond
, 0)
1280 && TREE_OPERAND (stmt
, 1) == TREE_OPERAND (cond
, 1))
1281 *location
= alloc_stmt_list ();
1285 /* Protect GOTOs in the arm of COND_EXPRs from being removed. They
1286 would be re-introduced during lowering. */
1287 data
->last_goto
= NULL
;
1292 remove_useless_stmts_tf (tree
*stmt_p
, struct rus_data
*data
)
1294 bool save_may_branch
, save_may_throw
;
1295 bool this_may_branch
, this_may_throw
;
1297 /* Collect may_branch and may_throw information for the body only. */
1298 save_may_branch
= data
->may_branch
;
1299 save_may_throw
= data
->may_throw
;
1300 data
->may_branch
= false;
1301 data
->may_throw
= false;
1302 data
->last_goto
= NULL
;
1304 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p
, 0), data
);
1306 this_may_branch
= data
->may_branch
;
1307 this_may_throw
= data
->may_throw
;
1308 data
->may_branch
|= save_may_branch
;
1309 data
->may_throw
|= save_may_throw
;
1310 data
->last_goto
= NULL
;
1312 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p
, 1), data
);
1314 /* If the body is empty, then we can emit the FINALLY block without
1315 the enclosing TRY_FINALLY_EXPR. */
1316 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p
, 0)))
1318 *stmt_p
= TREE_OPERAND (*stmt_p
, 1);
1319 data
->repeat
= true;
1322 /* If the handler is empty, then we can emit the TRY block without
1323 the enclosing TRY_FINALLY_EXPR. */
1324 else if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p
, 1)))
1326 *stmt_p
= TREE_OPERAND (*stmt_p
, 0);
1327 data
->repeat
= true;
1330 /* If the body neither throws, nor branches, then we can safely
1331 string the TRY and FINALLY blocks together. */
1332 else if (!this_may_branch
&& !this_may_throw
)
1334 tree stmt
= *stmt_p
;
1335 *stmt_p
= TREE_OPERAND (stmt
, 0);
1336 append_to_statement_list (TREE_OPERAND (stmt
, 1), stmt_p
);
1337 data
->repeat
= true;
1343 remove_useless_stmts_tc (tree
*stmt_p
, struct rus_data
*data
)
1345 bool save_may_throw
, this_may_throw
;
1346 tree_stmt_iterator i
;
1349 /* Collect may_throw information for the body only. */
1350 save_may_throw
= data
->may_throw
;
1351 data
->may_throw
= false;
1352 data
->last_goto
= NULL
;
1354 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p
, 0), data
);
1356 this_may_throw
= data
->may_throw
;
1357 data
->may_throw
= save_may_throw
;
1359 /* If the body cannot throw, then we can drop the entire TRY_CATCH_EXPR. */
1360 if (!this_may_throw
)
1362 if (warn_notreached
)
1363 remove_useless_stmts_warn_notreached (TREE_OPERAND (*stmt_p
, 1));
1364 *stmt_p
= TREE_OPERAND (*stmt_p
, 0);
1365 data
->repeat
= true;
1369 /* Process the catch clause specially. We may be able to tell that
1370 no exceptions propagate past this point. */
1372 this_may_throw
= true;
1373 i
= tsi_start (TREE_OPERAND (*stmt_p
, 1));
1374 stmt
= tsi_stmt (i
);
1375 data
->last_goto
= NULL
;
1377 switch (TREE_CODE (stmt
))
1380 for (; !tsi_end_p (i
); tsi_next (&i
))
1382 stmt
= tsi_stmt (i
);
1383 /* If we catch all exceptions, then the body does not
1384 propagate exceptions past this point. */
1385 if (CATCH_TYPES (stmt
) == NULL
)
1386 this_may_throw
= false;
1387 data
->last_goto
= NULL
;
1388 remove_useless_stmts_1 (&CATCH_BODY (stmt
), data
);
1392 case EH_FILTER_EXPR
:
1393 if (EH_FILTER_MUST_NOT_THROW (stmt
))
1394 this_may_throw
= false;
1395 else if (EH_FILTER_TYPES (stmt
) == NULL
)
1396 this_may_throw
= false;
1397 remove_useless_stmts_1 (&EH_FILTER_FAILURE (stmt
), data
);
1401 /* Otherwise this is a cleanup. */
1402 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p
, 1), data
);
1404 /* If the cleanup is empty, then we can emit the TRY block without
1405 the enclosing TRY_CATCH_EXPR. */
1406 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p
, 1)))
1408 *stmt_p
= TREE_OPERAND (*stmt_p
, 0);
1409 data
->repeat
= true;
1413 data
->may_throw
|= this_may_throw
;
1418 remove_useless_stmts_bind (tree
*stmt_p
, struct rus_data
*data
)
1422 /* First remove anything underneath the BIND_EXPR. */
1423 remove_useless_stmts_1 (&BIND_EXPR_BODY (*stmt_p
), data
);
1425 /* If the BIND_EXPR has no variables, then we can pull everything
1426 up one level and remove the BIND_EXPR, unless this is the toplevel
1427 BIND_EXPR for the current function or an inlined function.
1429 When this situation occurs we will want to apply this
1430 optimization again. */
1431 block
= BIND_EXPR_BLOCK (*stmt_p
);
1432 if (BIND_EXPR_VARS (*stmt_p
) == NULL_TREE
1433 && *stmt_p
!= DECL_SAVED_TREE (current_function_decl
)
1435 || ! BLOCK_ABSTRACT_ORIGIN (block
)
1436 || (TREE_CODE (BLOCK_ABSTRACT_ORIGIN (block
))
1439 *stmt_p
= BIND_EXPR_BODY (*stmt_p
);
1440 data
->repeat
= true;
1446 remove_useless_stmts_goto (tree
*stmt_p
, struct rus_data
*data
)
1448 tree dest
= GOTO_DESTINATION (*stmt_p
);
1450 data
->may_branch
= true;
1451 data
->last_goto
= NULL
;
1453 /* Record the last goto expr, so that we can delete it if unnecessary. */
1454 if (TREE_CODE (dest
) == LABEL_DECL
)
1455 data
->last_goto
= stmt_p
;
1460 remove_useless_stmts_label (tree
*stmt_p
, struct rus_data
*data
)
1462 tree label
= LABEL_EXPR_LABEL (*stmt_p
);
1464 data
->has_label
= true;
1466 /* We do want to jump across non-local label receiver code. */
1467 if (DECL_NONLOCAL (label
))
1468 data
->last_goto
= NULL
;
1470 else if (data
->last_goto
&& GOTO_DESTINATION (*data
->last_goto
) == label
)
1472 *data
->last_goto
= build_empty_stmt ();
1473 data
->repeat
= true;
1476 /* ??? Add something here to delete unused labels. */
1480 /* If the function is "const" or "pure", then clear TREE_SIDE_EFFECTS on its
1481 decl. This allows us to eliminate redundant or useless
1482 calls to "const" functions.
1484 Gimplifier already does the same operation, but we may notice functions
1485 being const and pure once their calls has been gimplified, so we need
1486 to update the flag. */
1489 update_call_expr_flags (tree call
)
1491 tree decl
= get_callee_fndecl (call
);
1494 if (call_expr_flags (call
) & (ECF_CONST
| ECF_PURE
))
1495 TREE_SIDE_EFFECTS (call
) = 0;
1496 if (TREE_NOTHROW (decl
))
1497 TREE_NOTHROW (call
) = 1;
1501 /* T is CALL_EXPR. Set current_function_calls_* flags. */
1504 notice_special_calls (tree t
)
1506 int flags
= call_expr_flags (t
);
1508 if (flags
& ECF_MAY_BE_ALLOCA
)
1509 current_function_calls_alloca
= true;
1510 if (flags
& ECF_RETURNS_TWICE
)
1511 current_function_calls_setjmp
= true;
1515 /* Clear flags set by notice_special_calls. Used by dead code removal
1516 to update the flags. */
1519 clear_special_calls (void)
1521 current_function_calls_alloca
= false;
1522 current_function_calls_setjmp
= false;
1527 remove_useless_stmts_1 (tree
*tp
, struct rus_data
*data
)
1531 switch (TREE_CODE (t
))
1534 remove_useless_stmts_cond (tp
, data
);
1537 case TRY_FINALLY_EXPR
:
1538 remove_useless_stmts_tf (tp
, data
);
1541 case TRY_CATCH_EXPR
:
1542 remove_useless_stmts_tc (tp
, data
);
1546 remove_useless_stmts_bind (tp
, data
);
1550 remove_useless_stmts_goto (tp
, data
);
1554 remove_useless_stmts_label (tp
, data
);
1559 data
->last_goto
= NULL
;
1560 data
->may_branch
= true;
1565 data
->last_goto
= NULL
;
1566 notice_special_calls (t
);
1567 update_call_expr_flags (t
);
1568 if (tree_could_throw_p (t
))
1569 data
->may_throw
= true;
1573 data
->last_goto
= NULL
;
1575 op
= get_call_expr_in (t
);
1578 update_call_expr_flags (op
);
1579 notice_special_calls (op
);
1581 if (tree_could_throw_p (t
))
1582 data
->may_throw
= true;
1585 case STATEMENT_LIST
:
1587 tree_stmt_iterator i
= tsi_start (t
);
1588 while (!tsi_end_p (i
))
1591 if (IS_EMPTY_STMT (t
))
1597 remove_useless_stmts_1 (tsi_stmt_ptr (i
), data
);
1600 if (TREE_CODE (t
) == STATEMENT_LIST
)
1602 tsi_link_before (&i
, t
, TSI_SAME_STMT
);
1612 data
->last_goto
= NULL
;
1616 data
->last_goto
= NULL
;
1622 remove_useless_stmts (void)
1624 struct rus_data data
;
1626 clear_special_calls ();
1630 memset (&data
, 0, sizeof (data
));
1631 remove_useless_stmts_1 (&DECL_SAVED_TREE (current_function_decl
), &data
);
1633 while (data
.repeat
);
1637 struct tree_opt_pass pass_remove_useless_stmts
=
1639 "useless", /* name */
1641 remove_useless_stmts
, /* execute */
1644 0, /* static_pass_number */
1646 PROP_gimple_any
, /* properties_required */
1647 0, /* properties_provided */
1648 0, /* properties_destroyed */
1649 0, /* todo_flags_start */
1650 TODO_dump_func
/* todo_flags_finish */
1654 /* Remove obviously useless statements in basic block BB. */
1657 cfg_remove_useless_stmts_bb (basic_block bb
)
1659 block_stmt_iterator bsi
;
1660 tree stmt
= NULL_TREE
;
1661 tree cond
, var
= NULL_TREE
, val
= NULL_TREE
;
1662 struct var_ann_d
*ann
;
1664 /* Check whether we come here from a condition, and if so, get the
1667 || bb
->pred
->pred_next
1668 || !(bb
->pred
->flags
& (EDGE_TRUE_VALUE
| EDGE_FALSE_VALUE
)))
1671 cond
= COND_EXPR_COND (last_stmt (bb
->pred
->src
));
1673 if (TREE_CODE (cond
) == VAR_DECL
|| TREE_CODE (cond
) == PARM_DECL
)
1676 val
= (bb
->pred
->flags
& EDGE_FALSE_VALUE
1677 ? boolean_false_node
: boolean_true_node
);
1679 else if (TREE_CODE (cond
) == TRUTH_NOT_EXPR
1680 && (TREE_CODE (TREE_OPERAND (cond
, 0)) == VAR_DECL
1681 || TREE_CODE (TREE_OPERAND (cond
, 0)) == PARM_DECL
))
1683 var
= TREE_OPERAND (cond
, 0);
1684 val
= (bb
->pred
->flags
& EDGE_FALSE_VALUE
1685 ? boolean_true_node
: boolean_false_node
);
1689 if (bb
->pred
->flags
& EDGE_FALSE_VALUE
)
1690 cond
= invert_truthvalue (cond
);
1691 if (TREE_CODE (cond
) == EQ_EXPR
1692 && (TREE_CODE (TREE_OPERAND (cond
, 0)) == VAR_DECL
1693 || TREE_CODE (TREE_OPERAND (cond
, 0)) == PARM_DECL
)
1694 && (TREE_CODE (TREE_OPERAND (cond
, 1)) == VAR_DECL
1695 || TREE_CODE (TREE_OPERAND (cond
, 1)) == PARM_DECL
1696 || TREE_CONSTANT (TREE_OPERAND (cond
, 1))))
1698 var
= TREE_OPERAND (cond
, 0);
1699 val
= TREE_OPERAND (cond
, 1);
1705 /* Only work for normal local variables. */
1706 ann
= var_ann (var
);
1709 || TREE_ADDRESSABLE (var
))
1712 if (! TREE_CONSTANT (val
))
1714 ann
= var_ann (val
);
1717 || TREE_ADDRESSABLE (val
))
1721 /* Ignore floating point variables, since comparison behaves weird for
1723 if (FLOAT_TYPE_P (TREE_TYPE (var
)))
1726 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
);)
1728 stmt
= bsi_stmt (bsi
);
1730 /* If the THEN/ELSE clause merely assigns a value to a variable/parameter
1731 which is already known to contain that value, then remove the useless
1732 THEN/ELSE clause. */
1733 if (TREE_CODE (stmt
) == MODIFY_EXPR
1734 && TREE_OPERAND (stmt
, 0) == var
1735 && operand_equal_p (val
, TREE_OPERAND (stmt
, 1), 0))
1741 /* Invalidate the var if we encounter something that could modify it. */
1742 if (TREE_CODE (stmt
) == ASM_EXPR
1743 || (TREE_CODE (stmt
) == MODIFY_EXPR
1744 && TREE_OPERAND (stmt
, 0) == var
))
1752 /* A CFG-aware version of remove_useless_stmts. */
1755 cfg_remove_useless_stmts (void)
1759 #ifdef ENABLE_CHECKING
1760 verify_flow_info ();
1765 cfg_remove_useless_stmts_bb (bb
);
1770 /* Remove PHI nodes associated with basic block BB and all edges out of BB. */
1773 remove_phi_nodes_and_edges_for_unreachable_block (basic_block bb
)
1777 /* Since this block is no longer reachable, we can just delete all
1778 of its PHI nodes. */
1779 phi
= phi_nodes (bb
);
1782 tree next
= PHI_CHAIN (phi
);
1783 remove_phi_node (phi
, NULL_TREE
, bb
);
1787 /* Remove edges to BB's successors. */
1788 while (bb
->succ
!= NULL
)
1789 ssa_remove_edge (bb
->succ
);
1793 /* Remove statements of basic block BB. */
1796 remove_bb (basic_block bb
)
1798 block_stmt_iterator i
;
1799 source_locus loc
= 0;
1803 fprintf (dump_file
, "Removing basic block %d\n", bb
->index
);
1804 if (dump_flags
& TDF_DETAILS
)
1806 dump_bb (bb
, dump_file
, 0);
1807 fprintf (dump_file
, "\n");
1811 /* Remove all the instructions in the block. */
1812 for (i
= bsi_start (bb
); !bsi_end_p (i
); bsi_remove (&i
))
1814 tree stmt
= bsi_stmt (i
);
1816 set_bb_for_stmt (stmt
, NULL
);
1818 /* Don't warn for removed gotos. Gotos are often removed due to
1819 jump threading, thus resulting in bogus warnings. Not great,
1820 since this way we lose warnings for gotos in the original
1821 program that are indeed unreachable. */
1822 if (TREE_CODE (stmt
) != GOTO_EXPR
&& EXPR_HAS_LOCATION (stmt
) && !loc
)
1823 #ifdef USE_MAPPED_LOCATION
1824 loc
= EXPR_LOCATION (stmt
);
1826 loc
= EXPR_LOCUS (stmt
);
1830 /* If requested, give a warning that the first statement in the
1831 block is unreachable. We walk statements backwards in the
1832 loop above, so the last statement we process is the first statement
1834 if (warn_notreached
&& loc
)
1835 #ifdef USE_MAPPED_LOCATION
1836 warning ("%Hwill never be executed", &loc
);
1838 warning ("%Hwill never be executed", loc
);
1841 remove_phi_nodes_and_edges_for_unreachable_block (bb
);
1845 /* Examine BB to determine if it is a forwarding block (a block which only
1846 transfers control to a new destination). If BB is a forwarding block,
1847 then return the edge leading to the ultimate destination. */
1850 tree_block_forwards_to (basic_block bb
)
1852 block_stmt_iterator bsi
;
1853 bb_ann_t ann
= bb_ann (bb
);
1856 /* If this block is not forwardable, then avoid useless work. */
1857 if (! ann
->forwardable
)
1860 /* Set this block to not be forwardable. This prevents infinite loops since
1861 any block currently under examination is considered non-forwardable. */
1862 ann
->forwardable
= 0;
1864 /* No forwarding is possible if this block is a special block (ENTRY/EXIT),
1865 this block has more than one successor, this block's single successor is
1866 reached via an abnormal edge, this block has phi nodes, or this block's
1867 single successor has phi nodes. */
1868 if (bb
== EXIT_BLOCK_PTR
1869 || bb
== ENTRY_BLOCK_PTR
1871 || bb
->succ
->succ_next
1872 || bb
->succ
->dest
== EXIT_BLOCK_PTR
1873 || (bb
->succ
->flags
& EDGE_ABNORMAL
) != 0
1875 || phi_nodes (bb
->succ
->dest
))
1878 /* Walk past any labels at the start of this block. */
1879 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
1881 stmt
= bsi_stmt (bsi
);
1882 if (TREE_CODE (stmt
) != LABEL_EXPR
)
1886 /* If we reached the end of this block we may be able to optimize this
1888 if (bsi_end_p (bsi
))
1892 /* Recursive call to pick up chains of forwarding blocks. */
1893 dest
= tree_block_forwards_to (bb
->succ
->dest
);
1895 /* If none found, we forward to bb->succ at minimum. */
1899 ann
->forwardable
= 1;
1903 /* No forwarding possible. */
1908 /* Try to remove superfluous control structures. */
1911 cleanup_control_flow (void)
1914 block_stmt_iterator bsi
;
1915 bool retval
= false;
1920 bsi
= bsi_last (bb
);
1922 if (bsi_end_p (bsi
))
1925 stmt
= bsi_stmt (bsi
);
1926 if (TREE_CODE (stmt
) == COND_EXPR
1927 || TREE_CODE (stmt
) == SWITCH_EXPR
)
1928 retval
|= cleanup_control_expr_graph (bb
, bsi
);
1934 /* Disconnect an unreachable block in the control expression starting
1938 cleanup_control_expr_graph (basic_block bb
, block_stmt_iterator bsi
)
1941 bool retval
= false;
1942 tree expr
= bsi_stmt (bsi
), val
;
1944 if (bb
->succ
->succ_next
)
1948 switch (TREE_CODE (expr
))
1951 val
= COND_EXPR_COND (expr
);
1955 val
= SWITCH_COND (expr
);
1956 if (TREE_CODE (val
) != INTEGER_CST
)
1964 taken_edge
= find_taken_edge (bb
, val
);
1968 /* Remove all the edges except the one that is always executed. */
1969 for (e
= bb
->succ
; e
; e
= next
)
1971 next
= e
->succ_next
;
1972 if (e
!= taken_edge
)
1974 taken_edge
->probability
+= e
->probability
;
1975 taken_edge
->count
+= e
->count
;
1976 ssa_remove_edge (e
);
1980 if (taken_edge
->probability
> REG_BR_PROB_BASE
)
1981 taken_edge
->probability
= REG_BR_PROB_BASE
;
1984 taken_edge
= bb
->succ
;
1987 taken_edge
->flags
= EDGE_FALLTHRU
;
1989 /* We removed some paths from the cfg. */
1990 if (dom_computed
[CDI_DOMINATORS
] >= DOM_CONS_OK
)
1991 dom_computed
[CDI_DOMINATORS
] = DOM_CONS_OK
;
1997 /* Given a control block BB and a predicate VAL, return the edge that
1998 will be taken out of the block. If VAL does not match a unique
1999 edge, NULL is returned. */
2002 find_taken_edge (basic_block bb
, tree val
)
2006 stmt
= last_stmt (bb
);
2008 #if defined ENABLE_CHECKING
2009 if (stmt
== NULL_TREE
|| !is_ctrl_stmt (stmt
))
2013 /* If VAL is a predicate of the form N RELOP N, where N is an
2014 SSA_NAME, we can always determine its truth value (except when
2015 doing floating point comparisons that may involve NaNs). */
2017 && TREE_CODE_CLASS (TREE_CODE (val
)) == '<'
2018 && TREE_OPERAND (val
, 0) == TREE_OPERAND (val
, 1)
2019 && TREE_CODE (TREE_OPERAND (val
, 0)) == SSA_NAME
2020 && (TREE_CODE (TREE_TYPE (TREE_OPERAND (val
, 0))) != REAL_TYPE
2021 || !HONOR_NANS (TYPE_MODE (TREE_TYPE (TREE_OPERAND (val
, 0))))))
2023 enum tree_code code
= TREE_CODE (val
);
2025 if (code
== EQ_EXPR
|| code
== LE_EXPR
|| code
== GE_EXPR
)
2026 val
= boolean_true_node
;
2027 else if (code
== LT_EXPR
|| code
== GT_EXPR
|| code
== NE_EXPR
)
2028 val
= boolean_false_node
;
2031 /* If VAL is not a constant, we can't determine which edge might
2033 if (val
== NULL
|| !really_constant_p (val
))
2036 if (TREE_CODE (stmt
) == COND_EXPR
)
2037 return find_taken_edge_cond_expr (bb
, val
);
2039 if (TREE_CODE (stmt
) == SWITCH_EXPR
)
2040 return find_taken_edge_switch_expr (bb
, val
);
2046 /* Given a constant value VAL and the entry block BB to a COND_EXPR
2047 statement, determine which of the two edges will be taken out of the
2048 block. Return NULL if either edge may be taken. */
2051 find_taken_edge_cond_expr (basic_block bb
, tree val
)
2053 edge true_edge
, false_edge
;
2055 extract_true_false_edges_from_block (bb
, &true_edge
, &false_edge
);
2057 /* If both edges of the branch lead to the same basic block, it doesn't
2058 matter which edge is taken. */
2059 if (true_edge
->dest
== false_edge
->dest
)
2062 /* Otherwise, try to determine which branch of the if() will be taken.
2063 If VAL is a constant but it can't be reduced to a 0 or a 1, then
2064 we don't really know which edge will be taken at runtime. This
2065 may happen when comparing addresses (e.g., if (&var1 == 4)). */
2066 if (integer_nonzerop (val
))
2068 else if (integer_zerop (val
))
2075 /* Given a constant value VAL and the entry block BB to a SWITCH_EXPR
2076 statement, determine which edge will be taken out of the block. Return
2077 NULL if any edge may be taken. */
2080 find_taken_edge_switch_expr (basic_block bb
, tree val
)
2082 tree switch_expr
, taken_case
;
2083 basic_block dest_bb
;
2086 if (TREE_CODE (val
) != INTEGER_CST
)
2089 switch_expr
= last_stmt (bb
);
2090 taken_case
= find_case_label_for_value (switch_expr
, val
);
2091 dest_bb
= label_to_block (CASE_LABEL (taken_case
));
2093 e
= find_edge (bb
, dest_bb
);
2100 /* Return the CASE_LABEL_EXPR that SWITCH_EXPR will take for VAL.
2101 We can make optimal use here of the fact that the case labels are
2102 sorted: We can do a binary search for a case matching VAL. */
2105 find_case_label_for_value (tree switch_expr
, tree val
)
2107 tree vec
= SWITCH_LABELS (switch_expr
);
2108 size_t low
, high
, n
= TREE_VEC_LENGTH (vec
);
2109 tree default_case
= TREE_VEC_ELT (vec
, n
- 1);
2111 for (low
= -1, high
= n
- 1; high
- low
> 1; )
2113 size_t i
= (high
+ low
) / 2;
2114 tree t
= TREE_VEC_ELT (vec
, i
);
2117 /* Cache the result of comparing CASE_LOW and val. */
2118 cmp
= tree_int_cst_compare (CASE_LOW (t
), val
);
2125 if (CASE_HIGH (t
) == NULL
)
2127 /* A singe-valued case label. */
2133 /* A case range. We can only handle integer ranges. */
2134 if (cmp
<= 0 && tree_int_cst_compare (CASE_HIGH (t
), val
) >= 0)
2139 return default_case
;
2143 /* If all the PHI nodes in DEST have alternatives for E1 and E2 and
2144 those alternatives are equal in each of the PHI nodes, then return
2145 true, else return false. */
2148 phi_alternatives_equal (basic_block dest
, edge e1
, edge e2
)
2150 tree phi
, val1
, val2
;
2153 for (phi
= phi_nodes (dest
); phi
; phi
= PHI_CHAIN (phi
))
2155 n1
= phi_arg_from_edge (phi
, e1
);
2156 n2
= phi_arg_from_edge (phi
, e2
);
2158 #ifdef ENABLE_CHECKING
2159 if (n1
< 0 || n2
< 0)
2163 val1
= PHI_ARG_DEF (phi
, n1
);
2164 val2
= PHI_ARG_DEF (phi
, n2
);
2166 if (!operand_equal_p (val1
, val2
, 0))
2174 /* Computing the Dominance Frontier:
2176 As described in Morgan, section 3.5, this may be done simply by
2177 walking the dominator tree bottom-up, computing the frontier for
2178 the children before the parent. When considering a block B,
2179 there are two cases:
2181 (1) A flow graph edge leaving B that does not lead to a child
2182 of B in the dominator tree must be a block that is either equal
2183 to B or not dominated by B. Such blocks belong in the frontier
2186 (2) Consider a block X in the frontier of one of the children C
2187 of B. If X is not equal to B and is not dominated by B, it
2188 is in the frontier of B. */
2191 compute_dominance_frontiers_1 (bitmap
*frontiers
, basic_block bb
, sbitmap done
)
2196 SET_BIT (done
, bb
->index
);
2198 /* Do the frontier of the children first. Not all children in the
2199 dominator tree (blocks dominated by this one) are children in the
2200 CFG, so check all blocks. */
2201 for (c
= first_dom_son (CDI_DOMINATORS
, bb
);
2203 c
= next_dom_son (CDI_DOMINATORS
, c
))
2205 if (! TEST_BIT (done
, c
->index
))
2206 compute_dominance_frontiers_1 (frontiers
, c
, done
);
2209 /* Find blocks conforming to rule (1) above. */
2210 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
2212 if (e
->dest
== EXIT_BLOCK_PTR
)
2214 if (get_immediate_dominator (CDI_DOMINATORS
, e
->dest
) != bb
)
2215 bitmap_set_bit (frontiers
[bb
->index
], e
->dest
->index
);
2218 /* Find blocks conforming to rule (2). */
2219 for (c
= first_dom_son (CDI_DOMINATORS
, bb
);
2221 c
= next_dom_son (CDI_DOMINATORS
, c
))
2225 EXECUTE_IF_SET_IN_BITMAP (frontiers
[c
->index
], 0, x
,
2227 if (get_immediate_dominator (CDI_DOMINATORS
, BASIC_BLOCK (x
)) != bb
)
2228 bitmap_set_bit (frontiers
[bb
->index
], x
);
2235 compute_dominance_frontiers (bitmap
*frontiers
)
2237 sbitmap done
= sbitmap_alloc (last_basic_block
);
2239 timevar_push (TV_DOM_FRONTIERS
);
2241 sbitmap_zero (done
);
2243 compute_dominance_frontiers_1 (frontiers
, ENTRY_BLOCK_PTR
->succ
->dest
, done
);
2245 sbitmap_free (done
);
2247 timevar_pop (TV_DOM_FRONTIERS
);
2252 /*---------------------------------------------------------------------------
2254 ---------------------------------------------------------------------------*/
2256 /* Dump tree-specific information of block BB to file OUTF. */
2259 tree_dump_bb (basic_block bb
, FILE *outf
, int indent
)
2261 dump_generic_bb (outf
, bb
, indent
, TDF_VOPS
);
2265 /* Dump a basic block on stderr. */
2268 debug_tree_bb (basic_block bb
)
2270 dump_bb (bb
, stderr
, 0);
2274 /* Dump basic block with index N on stderr. */
2277 debug_tree_bb_n (int n
)
2279 debug_tree_bb (BASIC_BLOCK (n
));
2280 return BASIC_BLOCK (n
);
2284 /* Dump the CFG on stderr.
2286 FLAGS are the same used by the tree dumping functions
2287 (see TDF_* in tree.h). */
2290 debug_tree_cfg (int flags
)
2292 dump_tree_cfg (stderr
, flags
);
2296 /* Dump the program showing basic block boundaries on the given FILE.
2298 FLAGS are the same used by the tree dumping functions (see TDF_* in
2302 dump_tree_cfg (FILE *file
, int flags
)
2304 if (flags
& TDF_DETAILS
)
2306 const char *funcname
2307 = lang_hooks
.decl_printable_name (current_function_decl
, 2);
2310 fprintf (file
, ";; Function %s\n\n", funcname
);
2311 fprintf (file
, ";; \n%d basic blocks, %d edges, last basic block %d.\n\n",
2312 n_basic_blocks
, n_edges
, last_basic_block
);
2314 brief_dump_cfg (file
);
2315 fprintf (file
, "\n");
2318 if (flags
& TDF_STATS
)
2319 dump_cfg_stats (file
);
2321 dump_function_to_file (current_function_decl
, file
, flags
| TDF_BLOCKS
);
2325 /* Dump CFG statistics on FILE. */
2328 dump_cfg_stats (FILE *file
)
2330 static long max_num_merged_labels
= 0;
2331 unsigned long size
, total
= 0;
2334 const char * const fmt_str
= "%-30s%-13s%12s\n";
2335 const char * const fmt_str_1
= "%-30s%13d%11lu%c\n";
2336 const char * const fmt_str_3
= "%-43s%11lu%c\n";
2337 const char *funcname
2338 = lang_hooks
.decl_printable_name (current_function_decl
, 2);
2341 fprintf (file
, "\nCFG Statistics for %s\n\n", funcname
);
2343 fprintf (file
, "---------------------------------------------------------\n");
2344 fprintf (file
, fmt_str
, "", " Number of ", "Memory");
2345 fprintf (file
, fmt_str
, "", " instances ", "used ");
2346 fprintf (file
, "---------------------------------------------------------\n");
2348 size
= n_basic_blocks
* sizeof (struct basic_block_def
);
2350 fprintf (file
, fmt_str_1
, "Basic blocks", n_basic_blocks
,
2351 SCALE (size
), LABEL (size
));
2357 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
2360 size
= n_edges
* sizeof (struct edge_def
);
2362 fprintf (file
, fmt_str_1
, "Edges", n_edges
, SCALE (size
), LABEL (size
));
2364 size
= n_basic_blocks
* sizeof (struct bb_ann_d
);
2366 fprintf (file
, fmt_str_1
, "Basic block annotations", n_basic_blocks
,
2367 SCALE (size
), LABEL (size
));
2369 fprintf (file
, "---------------------------------------------------------\n");
2370 fprintf (file
, fmt_str_3
, "Total memory used by CFG data", SCALE (total
),
2372 fprintf (file
, "---------------------------------------------------------\n");
2373 fprintf (file
, "\n");
2375 if (cfg_stats
.num_merged_labels
> max_num_merged_labels
)
2376 max_num_merged_labels
= cfg_stats
.num_merged_labels
;
2378 fprintf (file
, "Coalesced label blocks: %ld (Max so far: %ld)\n",
2379 cfg_stats
.num_merged_labels
, max_num_merged_labels
);
2381 fprintf (file
, "\n");
2385 /* Dump CFG statistics on stderr. Keep extern so that it's always
2386 linked in the final executable. */
2389 debug_cfg_stats (void)
2391 dump_cfg_stats (stderr
);
2395 /* Dump the flowgraph to a .vcg FILE. */
2398 tree_cfg2vcg (FILE *file
)
2402 const char *funcname
2403 = lang_hooks
.decl_printable_name (current_function_decl
, 2);
2405 /* Write the file header. */
2406 fprintf (file
, "graph: { title: \"%s\"\n", funcname
);
2407 fprintf (file
, "node: { title: \"ENTRY\" label: \"ENTRY\" }\n");
2408 fprintf (file
, "node: { title: \"EXIT\" label: \"EXIT\" }\n");
2410 /* Write blocks and edges. */
2411 for (e
= ENTRY_BLOCK_PTR
->succ
; e
; e
= e
->succ_next
)
2413 fprintf (file
, "edge: { sourcename: \"ENTRY\" targetname: \"%d\"",
2416 if (e
->flags
& EDGE_FAKE
)
2417 fprintf (file
, " linestyle: dotted priority: 10");
2419 fprintf (file
, " linestyle: solid priority: 100");
2421 fprintf (file
, " }\n");
2427 enum tree_code head_code
, end_code
;
2428 const char *head_name
, *end_name
;
2431 tree first
= first_stmt (bb
);
2432 tree last
= last_stmt (bb
);
2436 head_code
= TREE_CODE (first
);
2437 head_name
= tree_code_name
[head_code
];
2438 head_line
= get_lineno (first
);
2441 head_name
= "no-statement";
2445 end_code
= TREE_CODE (last
);
2446 end_name
= tree_code_name
[end_code
];
2447 end_line
= get_lineno (last
);
2450 end_name
= "no-statement";
2452 fprintf (file
, "node: { title: \"%d\" label: \"#%d\\n%s (%d)\\n%s (%d)\"}\n",
2453 bb
->index
, bb
->index
, head_name
, head_line
, end_name
,
2456 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
2458 if (e
->dest
== EXIT_BLOCK_PTR
)
2459 fprintf (file
, "edge: { sourcename: \"%d\" targetname: \"EXIT\"", bb
->index
);
2461 fprintf (file
, "edge: { sourcename: \"%d\" targetname: \"%d\"", bb
->index
, e
->dest
->index
);
2463 if (e
->flags
& EDGE_FAKE
)
2464 fprintf (file
, " priority: 10 linestyle: dotted");
2466 fprintf (file
, " priority: 100 linestyle: solid");
2468 fprintf (file
, " }\n");
2471 if (bb
->next_bb
!= EXIT_BLOCK_PTR
)
2475 fputs ("}\n\n", file
);
2480 /*---------------------------------------------------------------------------
2481 Miscellaneous helpers
2482 ---------------------------------------------------------------------------*/
2484 /* Return true if T represents a stmt that always transfers control. */
2487 is_ctrl_stmt (tree t
)
2489 return (TREE_CODE (t
) == COND_EXPR
2490 || TREE_CODE (t
) == SWITCH_EXPR
2491 || TREE_CODE (t
) == GOTO_EXPR
2492 || TREE_CODE (t
) == RETURN_EXPR
2493 || TREE_CODE (t
) == RESX_EXPR
);
2497 /* Return true if T is a statement that may alter the flow of control
2498 (e.g., a call to a non-returning function). */
2501 is_ctrl_altering_stmt (tree t
)
2505 #if defined ENABLE_CHECKING
2510 call
= get_call_expr_in (t
);
2513 /* A non-pure/const CALL_EXPR alters flow control if the current
2514 function has nonlocal labels. */
2515 if (TREE_SIDE_EFFECTS (call
) && current_function_has_nonlocal_label
)
2518 /* A CALL_EXPR also alters control flow if it does not return. */
2519 if (call_expr_flags (call
) & (ECF_NORETURN
| ECF_LONGJMP
))
2523 /* If a statement can throw, it alters control flow. */
2524 return tree_can_throw_internal (t
);
2528 /* Return true if T is a computed goto. */
2531 computed_goto_p (tree t
)
2533 return (TREE_CODE (t
) == GOTO_EXPR
2534 && TREE_CODE (GOTO_DESTINATION (t
)) != LABEL_DECL
);
2538 /* Checks whether EXPR is a simple local goto. */
2541 simple_goto_p (tree expr
)
2543 return (TREE_CODE (expr
) == GOTO_EXPR
2544 && TREE_CODE (GOTO_DESTINATION (expr
)) == LABEL_DECL
);
2548 /* Return true if T should start a new basic block. PREV_T is the
2549 statement preceding T. It is used when T is a label or a case label.
2550 Labels should only start a new basic block if their previous statement
2551 wasn't a label. Otherwise, sequence of labels would generate
2552 unnecessary basic blocks that only contain a single label. */
2555 stmt_starts_bb_p (tree t
, tree prev_t
)
2557 enum tree_code code
;
2562 /* LABEL_EXPRs start a new basic block only if the preceding
2563 statement wasn't a label of the same type. This prevents the
2564 creation of consecutive blocks that have nothing but a single
2566 code
= TREE_CODE (t
);
2567 if (code
== LABEL_EXPR
)
2569 /* Nonlocal and computed GOTO targets always start a new block. */
2570 if (code
== LABEL_EXPR
2571 && (DECL_NONLOCAL (LABEL_EXPR_LABEL (t
))
2572 || FORCED_LABEL (LABEL_EXPR_LABEL (t
))))
2575 if (prev_t
&& TREE_CODE (prev_t
) == code
)
2577 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (prev_t
)))
2580 cfg_stats
.num_merged_labels
++;
2591 /* Return true if T should end a basic block. */
2594 stmt_ends_bb_p (tree t
)
2596 return is_ctrl_stmt (t
) || is_ctrl_altering_stmt (t
);
2600 /* Add gotos that used to be represented implicitly in the CFG. */
2603 disband_implicit_edges (void)
2606 block_stmt_iterator last
;
2612 last
= bsi_last (bb
);
2613 stmt
= last_stmt (bb
);
2615 if (stmt
&& TREE_CODE (stmt
) == COND_EXPR
)
2617 /* Remove superfluous gotos from COND_EXPR branches. Moved
2618 from cfg_remove_useless_stmts here since it violates the
2619 invariants for tree--cfg correspondence and thus fits better
2620 here where we do it anyway. */
2621 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
2623 if (e
->dest
!= bb
->next_bb
)
2626 if (e
->flags
& EDGE_TRUE_VALUE
)
2627 COND_EXPR_THEN (stmt
) = build_empty_stmt ();
2628 else if (e
->flags
& EDGE_FALSE_VALUE
)
2629 COND_EXPR_ELSE (stmt
) = build_empty_stmt ();
2632 e
->flags
|= EDGE_FALLTHRU
;
2638 if (stmt
&& TREE_CODE (stmt
) == RETURN_EXPR
)
2640 /* Remove the RETURN_EXPR if we may fall though to the exit
2643 || bb
->succ
->succ_next
2644 || bb
->succ
->dest
!= EXIT_BLOCK_PTR
)
2647 if (bb
->next_bb
== EXIT_BLOCK_PTR
2648 && !TREE_OPERAND (stmt
, 0))
2651 bb
->succ
->flags
|= EDGE_FALLTHRU
;
2656 /* There can be no fallthru edge if the last statement is a control
2658 if (stmt
&& is_ctrl_stmt (stmt
))
2661 /* Find a fallthru edge and emit the goto if necessary. */
2662 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
2663 if (e
->flags
& EDGE_FALLTHRU
)
2666 if (!e
|| e
->dest
== bb
->next_bb
)
2669 if (e
->dest
== EXIT_BLOCK_PTR
)
2672 label
= tree_block_label (e
->dest
);
2674 stmt
= build1 (GOTO_EXPR
, void_type_node
, label
);
2675 #ifdef USE_MAPPED_LOCATION
2676 SET_EXPR_LOCATION (stmt
, e
->goto_locus
);
2678 SET_EXPR_LOCUS (stmt
, e
->goto_locus
);
2680 bsi_insert_after (&last
, stmt
, BSI_NEW_STMT
);
2681 e
->flags
&= ~EDGE_FALLTHRU
;
2685 /* Remove block annotations and other datastructures. */
2688 delete_tree_cfg_annotations (void)
2691 if (n_basic_blocks
> 0)
2692 free_blocks_annotations ();
2694 label_to_block_map
= NULL
;
2701 /* Return the first statement in basic block BB. */
2704 first_stmt (basic_block bb
)
2706 block_stmt_iterator i
= bsi_start (bb
);
2707 return !bsi_end_p (i
) ? bsi_stmt (i
) : NULL_TREE
;
2711 /* Return the last statement in basic block BB. */
2714 last_stmt (basic_block bb
)
2716 block_stmt_iterator b
= bsi_last (bb
);
2717 return !bsi_end_p (b
) ? bsi_stmt (b
) : NULL_TREE
;
2721 /* Return a pointer to the last statement in block BB. */
2724 last_stmt_ptr (basic_block bb
)
2726 block_stmt_iterator last
= bsi_last (bb
);
2727 return !bsi_end_p (last
) ? bsi_stmt_ptr (last
) : NULL
;
2731 /* Return the last statement of an otherwise empty block. Return NULL
2732 if the block is totally empty, or if it contains more than one
2736 last_and_only_stmt (basic_block bb
)
2738 block_stmt_iterator i
= bsi_last (bb
);
2744 last
= bsi_stmt (i
);
2749 /* Empty statements should no longer appear in the instruction stream.
2750 Everything that might have appeared before should be deleted by
2751 remove_useless_stmts, and the optimizers should just bsi_remove
2752 instead of smashing with build_empty_stmt.
2754 Thus the only thing that should appear here in a block containing
2755 one executable statement is a label. */
2756 prev
= bsi_stmt (i
);
2757 if (TREE_CODE (prev
) == LABEL_EXPR
)
2764 /* Mark BB as the basic block holding statement T. */
2767 set_bb_for_stmt (tree t
, basic_block bb
)
2769 if (TREE_CODE (t
) == STATEMENT_LIST
)
2771 tree_stmt_iterator i
;
2772 for (i
= tsi_start (t
); !tsi_end_p (i
); tsi_next (&i
))
2773 set_bb_for_stmt (tsi_stmt (i
), bb
);
2777 stmt_ann_t ann
= get_stmt_ann (t
);
2780 /* If the statement is a label, add the label to block-to-labels map
2781 so that we can speed up edge creation for GOTO_EXPRs. */
2782 if (TREE_CODE (t
) == LABEL_EXPR
)
2786 t
= LABEL_EXPR_LABEL (t
);
2787 uid
= LABEL_DECL_UID (t
);
2790 LABEL_DECL_UID (t
) = uid
= cfun
->last_label_uid
++;
2791 if (VARRAY_SIZE (label_to_block_map
) <= (unsigned) uid
)
2792 VARRAY_GROW (label_to_block_map
, 3 * uid
/ 2);
2796 #ifdef ENABLE_CHECKING
2797 /* We're moving an existing label. Make sure that we've
2798 removed it from the old block. */
2799 if (bb
&& VARRAY_BB (label_to_block_map
, uid
))
2803 VARRAY_BB (label_to_block_map
, uid
) = bb
;
2809 /* Insert statement (or statement list) T before the statement
2810 pointed-to by iterator I. M specifies how to update iterator I
2811 after insertion (see enum bsi_iterator_update). */
2814 bsi_insert_before (block_stmt_iterator
*i
, tree t
, enum bsi_iterator_update m
)
2816 set_bb_for_stmt (t
, i
->bb
);
2818 tsi_link_before (&i
->tsi
, t
, m
);
2822 /* Insert statement (or statement list) T after the statement
2823 pointed-to by iterator I. M specifies how to update iterator I
2824 after insertion (see enum bsi_iterator_update). */
2827 bsi_insert_after (block_stmt_iterator
*i
, tree t
, enum bsi_iterator_update m
)
2829 set_bb_for_stmt (t
, i
->bb
);
2831 tsi_link_after (&i
->tsi
, t
, m
);
2835 /* Remove the statement pointed to by iterator I. The iterator is updated
2836 to the next statement. */
2839 bsi_remove (block_stmt_iterator
*i
)
2841 tree t
= bsi_stmt (*i
);
2842 set_bb_for_stmt (t
, NULL
);
2844 tsi_delink (&i
->tsi
);
2848 /* Move the statement at FROM so it comes right after the statement at TO. */
2851 bsi_move_after (block_stmt_iterator
*from
, block_stmt_iterator
*to
)
2853 tree stmt
= bsi_stmt (*from
);
2855 bsi_insert_after (to
, stmt
, BSI_SAME_STMT
);
2859 /* Move the statement at FROM so it comes right before the statement at TO. */
2862 bsi_move_before (block_stmt_iterator
*from
, block_stmt_iterator
*to
)
2864 tree stmt
= bsi_stmt (*from
);
2866 bsi_insert_before (to
, stmt
, BSI_SAME_STMT
);
2870 /* Move the statement at FROM to the end of basic block BB. */
2873 bsi_move_to_bb_end (block_stmt_iterator
*from
, basic_block bb
)
2875 block_stmt_iterator last
= bsi_last (bb
);
2877 /* Have to check bsi_end_p because it could be an empty block. */
2878 if (!bsi_end_p (last
) && is_ctrl_stmt (bsi_stmt (last
)))
2879 bsi_move_before (from
, &last
);
2881 bsi_move_after (from
, &last
);
2885 /* Replace the contents of the statement pointed to by iterator BSI
2886 with STMT. If PRESERVE_EH_INFO is true, the exception handling
2887 information of the original statement is preserved. */
2890 bsi_replace (const block_stmt_iterator
*bsi
, tree stmt
, bool preserve_eh_info
)
2893 tree orig_stmt
= bsi_stmt (*bsi
);
2895 SET_EXPR_LOCUS (stmt
, EXPR_LOCUS (orig_stmt
));
2896 set_bb_for_stmt (stmt
, bsi
->bb
);
2898 /* Preserve EH region information from the original statement, if
2899 requested by the caller. */
2900 if (preserve_eh_info
)
2902 eh_region
= lookup_stmt_eh_region (orig_stmt
);
2904 add_stmt_to_eh_region (stmt
, eh_region
);
2907 *bsi_stmt_ptr (*bsi
) = stmt
;
2912 /* Insert the statement pointed-to by BSI into edge E. Every attempt
2913 is made to place the statement in an existing basic block, but
2914 sometimes that isn't possible. When it isn't possible, the edge is
2915 split and the statement is added to the new block.
2917 In all cases, the returned *BSI points to the correct location. The
2918 return value is true if insertion should be done after the location,
2919 or false if it should be done before the location. */
2922 tree_find_edge_insert_loc (edge e
, block_stmt_iterator
*bsi
)
2924 basic_block dest
, src
;
2930 /* If the destination has one predecessor which has no PHI nodes,
2931 insert there. Except for the exit block.
2933 The requirement for no PHI nodes could be relaxed. Basically we
2934 would have to examine the PHIs to prove that none of them used
2935 the value set by the statement we want to insert on E. That
2936 hardly seems worth the effort. */
2937 if (dest
->pred
->pred_next
== NULL
2938 && ! phi_nodes (dest
)
2939 && dest
!= EXIT_BLOCK_PTR
)
2941 *bsi
= bsi_start (dest
);
2942 if (bsi_end_p (*bsi
))
2945 /* Make sure we insert after any leading labels. */
2946 tmp
= bsi_stmt (*bsi
);
2947 while (TREE_CODE (tmp
) == LABEL_EXPR
)
2950 if (bsi_end_p (*bsi
))
2952 tmp
= bsi_stmt (*bsi
);
2955 if (bsi_end_p (*bsi
))
2957 *bsi
= bsi_last (dest
);
2964 /* If the source has one successor, the edge is not abnormal and
2965 the last statement does not end a basic block, insert there.
2966 Except for the entry block. */
2968 if ((e
->flags
& EDGE_ABNORMAL
) == 0
2969 && src
->succ
->succ_next
== NULL
2970 && src
!= ENTRY_BLOCK_PTR
)
2972 *bsi
= bsi_last (src
);
2973 if (bsi_end_p (*bsi
))
2976 tmp
= bsi_stmt (*bsi
);
2977 if (!stmt_ends_bb_p (tmp
))
2980 /* Insert code just before returning the value. We may need to decompose
2981 the return in the case it contains non-trivial operand. */
2982 if (TREE_CODE (tmp
) == RETURN_EXPR
)
2984 tree op
= TREE_OPERAND (tmp
, 0);
2985 if (!is_gimple_val (op
))
2987 if (TREE_CODE (op
) != MODIFY_EXPR
)
2989 bsi_insert_before (bsi
, op
, BSI_NEW_STMT
);
2990 TREE_OPERAND (tmp
, 0) = TREE_OPERAND (op
, 0);
2997 /* Otherwise, create a new basic block, and split this edge. */
2998 dest
= split_edge (e
);
3004 /* This routine will commit all pending edge insertions, creating any new
3005 basic blocks which are necessary.
3007 If specified, NEW_BLOCKS returns a count of the number of new basic
3008 blocks which were created. */
3011 bsi_commit_edge_inserts (int *new_blocks
)
3017 blocks
= n_basic_blocks
;
3019 bsi_commit_edge_inserts_1 (ENTRY_BLOCK_PTR
->succ
);
3022 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
3023 bsi_commit_edge_inserts_1 (e
);
3026 *new_blocks
= n_basic_blocks
- blocks
;
3030 /* Commit insertions pending at edge E. */
3033 bsi_commit_edge_inserts_1 (edge e
)
3035 if (PENDING_STMT (e
))
3037 block_stmt_iterator bsi
;
3038 tree stmt
= PENDING_STMT (e
);
3040 PENDING_STMT (e
) = NULL_TREE
;
3042 if (tree_find_edge_insert_loc (e
, &bsi
))
3043 bsi_insert_after (&bsi
, stmt
, BSI_NEW_STMT
);
3045 bsi_insert_before (&bsi
, stmt
, BSI_NEW_STMT
);
3050 /* Add STMT to the pending list of edge E. No actual insertion is
3051 made until a call to bsi_commit_edge_inserts () is made. */
3054 bsi_insert_on_edge (edge e
, tree stmt
)
3056 append_to_statement_list (stmt
, &PENDING_STMT (e
));
3060 /*---------------------------------------------------------------------------
3061 Tree specific functions for CFG manipulation
3062 ---------------------------------------------------------------------------*/
3064 /* Split a (typically critical) edge EDGE_IN. Return the new block.
3065 Abort on abnormal edges. */
3068 tree_split_edge (edge edge_in
)
3070 basic_block new_bb
, after_bb
, dest
, src
;
3075 /* Abnormal edges cannot be split. */
3076 if (edge_in
->flags
& EDGE_ABNORMAL
)
3080 dest
= edge_in
->dest
;
3082 /* Place the new block in the block list. Try to keep the new block
3083 near its "logical" location. This is of most help to humans looking
3084 at debugging dumps. */
3085 for (e
= dest
->pred
; e
; e
= e
->pred_next
)
3086 if (e
->src
->next_bb
== dest
)
3089 after_bb
= dest
->prev_bb
;
3091 after_bb
= edge_in
->src
;
3093 new_bb
= create_empty_bb (after_bb
);
3094 new_edge
= make_edge (new_bb
, dest
, EDGE_FALLTHRU
);
3096 /* Find all the PHI arguments on the original edge, and change them to
3097 the new edge. Do it before redirection, so that the argument does not
3099 for (phi
= phi_nodes (dest
); phi
; phi
= PHI_CHAIN (phi
))
3101 num_elem
= PHI_NUM_ARGS (phi
);
3102 for (i
= 0; i
< num_elem
; i
++)
3103 if (PHI_ARG_EDGE (phi
, i
) == edge_in
)
3105 PHI_ARG_EDGE (phi
, i
) = new_edge
;
3110 if (!redirect_edge_and_branch (edge_in
, new_bb
))
3113 if (PENDING_STMT (edge_in
))
3120 /* Return true when BB has label LABEL in it. */
3123 has_label_p (basic_block bb
, tree label
)
3125 block_stmt_iterator bsi
;
3127 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
3129 tree stmt
= bsi_stmt (bsi
);
3131 if (TREE_CODE (stmt
) != LABEL_EXPR
)
3133 if (LABEL_EXPR_LABEL (stmt
) == label
)
3140 /* Callback for walk_tree, check that all elements with address taken are
3141 properly noticed as such. */
3144 verify_expr (tree
*tp
, int *walk_subtrees
, void *data ATTRIBUTE_UNUSED
)
3151 /* Check operand N for being valid GIMPLE and give error MSG if not.
3152 We check for constants explicitly since they are not considered
3153 gimple invariants if they overflowed. */
3154 #define CHECK_OP(N, MSG) \
3155 do { if (TREE_CODE_CLASS (TREE_CODE (TREE_OPERAND (t, N))) != 'c' \
3156 && !is_gimple_val (TREE_OPERAND (t, N))) \
3157 { error (MSG); return TREE_OPERAND (t, N); }} while (0)
3159 switch (TREE_CODE (t
))
3162 if (SSA_NAME_IN_FREE_LIST (t
))
3164 error ("SSA name in freelist but still referenced");
3170 x
= TREE_OPERAND (t
, 0);
3171 if (TREE_CODE (x
) == BIT_FIELD_REF
3172 && is_gimple_reg (TREE_OPERAND (x
, 0)))
3174 error ("GIMPLE register modified with BIT_FIELD_REF");
3180 /* Skip any references (they will be checked when we recurse down the
3181 tree) and ensure that any variable used as a prefix is marked
3183 for (x
= TREE_OPERAND (t
, 0);
3184 (handled_component_p (x
)
3185 || TREE_CODE (x
) == REALPART_EXPR
3186 || TREE_CODE (x
) == IMAGPART_EXPR
);
3187 x
= TREE_OPERAND (x
, 0))
3190 if (TREE_CODE (x
) != VAR_DECL
&& TREE_CODE (x
) != PARM_DECL
)
3192 if (!TREE_ADDRESSABLE (x
))
3194 error ("address taken, but ADDRESSABLE bit not set");
3200 x
= TREE_OPERAND (t
, 0);
3201 if (TREE_CODE (TREE_TYPE (x
)) != BOOLEAN_TYPE
)
3203 error ("non-boolean used in condition");
3210 case FIX_TRUNC_EXPR
:
3212 case FIX_FLOOR_EXPR
:
3213 case FIX_ROUND_EXPR
:
3218 case NON_LVALUE_EXPR
:
3219 case TRUTH_NOT_EXPR
:
3220 CHECK_OP (0, "Invalid operand to unary operator");
3227 case ARRAY_RANGE_REF
:
3229 case VIEW_CONVERT_EXPR
:
3230 /* We have a nest of references. Verify that each of the operands
3231 that determine where to reference is either a constant or a variable,
3232 verify that the base is valid, and then show we've already checked
3234 while (TREE_CODE (t
) == REALPART_EXPR
|| TREE_CODE (t
) == IMAGPART_EXPR
3235 || handled_component_p (t
))
3237 if (TREE_CODE (t
) == COMPONENT_REF
&& TREE_OPERAND (t
, 2))
3238 CHECK_OP (2, "Invalid COMPONENT_REF offset operator");
3239 else if (TREE_CODE (t
) == ARRAY_REF
3240 || TREE_CODE (t
) == ARRAY_RANGE_REF
)
3242 CHECK_OP (1, "Invalid array index.");
3243 if (TREE_OPERAND (t
, 2))
3244 CHECK_OP (2, "Invalid array lower bound.");
3245 if (TREE_OPERAND (t
, 3))
3246 CHECK_OP (3, "Invalid array stride.");
3248 else if (TREE_CODE (t
) == BIT_FIELD_REF
)
3250 CHECK_OP (1, "Invalid operand to BIT_FIELD_REF");
3251 CHECK_OP (2, "Invalid operand to BIT_FIELD_REF");
3254 t
= TREE_OPERAND (t
, 0);
3257 if (TREE_CODE_CLASS (TREE_CODE (t
)) != 'c'
3258 && !is_gimple_lvalue (t
))
3260 error ("Invalid reference prefix.");
3272 case UNORDERED_EXPR
:
3283 case TRUNC_DIV_EXPR
:
3285 case FLOOR_DIV_EXPR
:
3286 case ROUND_DIV_EXPR
:
3287 case TRUNC_MOD_EXPR
:
3289 case FLOOR_MOD_EXPR
:
3290 case ROUND_MOD_EXPR
:
3292 case EXACT_DIV_EXPR
:
3302 CHECK_OP (0, "Invalid operand to binary operator");
3303 CHECK_OP (1, "Invalid operand to binary operator");
3315 /* Verify STMT, return true if STMT is not in GIMPLE form.
3316 TODO: Implement type checking. */
3319 verify_stmt (tree stmt
, bool last_in_block
)
3323 if (!is_gimple_stmt (stmt
))
3325 error ("Is not a valid GIMPLE statement.");
3329 addr
= walk_tree (&stmt
, verify_expr
, NULL
, NULL
);
3332 debug_generic_stmt (addr
);
3336 /* If the statement is marked as part of an EH region, then it is
3337 expected that the statement could throw. Verify that when we
3338 have optimizations that simplify statements such that we prove
3339 that they cannot throw, that we update other data structures
3341 if (lookup_stmt_eh_region (stmt
) >= 0)
3343 if (!tree_could_throw_p (stmt
))
3345 error ("Statement marked for throw, but doesn't.");
3348 if (!last_in_block
&& tree_can_throw_internal (stmt
))
3350 error ("Statement marked for throw in middle of block.");
3358 debug_generic_stmt (stmt
);
3363 /* Return true when the T can be shared. */
3366 tree_node_can_be_shared (tree t
)
3368 if (TYPE_P (t
) || DECL_P (t
)
3369 /* We check for constants explicitly since they are not considered
3370 gimple invariants if they overflowed. */
3371 || TREE_CODE_CLASS (TREE_CODE (t
)) == 'c'
3372 || is_gimple_min_invariant (t
)
3373 || TREE_CODE (t
) == SSA_NAME
)
3376 while (((TREE_CODE (t
) == ARRAY_REF
|| TREE_CODE (t
) == ARRAY_RANGE_REF
)
3377 /* We check for constants explicitly since they are not considered
3378 gimple invariants if they overflowed. */
3379 && (TREE_CODE_CLASS (TREE_CODE (TREE_OPERAND (t
, 1))) == 'c'
3380 || is_gimple_min_invariant (TREE_OPERAND (t
, 1))))
3381 || (TREE_CODE (t
) == COMPONENT_REF
3382 || TREE_CODE (t
) == REALPART_EXPR
3383 || TREE_CODE (t
) == IMAGPART_EXPR
))
3384 t
= TREE_OPERAND (t
, 0);
3393 /* Called via walk_trees. Verify tree sharing. */
3396 verify_node_sharing (tree
* tp
, int *walk_subtrees
, void *data
)
3398 htab_t htab
= (htab_t
) data
;
3401 if (tree_node_can_be_shared (*tp
))
3403 *walk_subtrees
= false;
3407 slot
= htab_find_slot (htab
, *tp
, INSERT
);
3416 /* Verify the GIMPLE statement chain. */
3422 block_stmt_iterator bsi
;
3427 timevar_push (TV_TREE_STMT_VERIFY
);
3428 htab
= htab_create (37, htab_hash_pointer
, htab_eq_pointer
, NULL
);
3435 for (phi
= phi_nodes (bb
); phi
; phi
= PHI_CHAIN (phi
))
3437 int phi_num_args
= PHI_NUM_ARGS (phi
);
3439 for (i
= 0; i
< phi_num_args
; i
++)
3441 tree t
= PHI_ARG_DEF (phi
, i
);
3444 /* Addressable variables do have SSA_NAMEs but they
3445 are not considered gimple values. */
3446 if (TREE_CODE (t
) != SSA_NAME
3447 && TREE_CODE (t
) != FUNCTION_DECL
3448 && !is_gimple_val (t
))
3450 error ("PHI def is not a GIMPLE value");
3451 debug_generic_stmt (phi
);
3452 debug_generic_stmt (t
);
3456 addr
= walk_tree (&t
, verify_expr
, NULL
, NULL
);
3459 debug_generic_stmt (addr
);
3463 addr
= walk_tree (&t
, verify_node_sharing
, htab
, NULL
);
3466 error ("Incorrect sharing of tree nodes");
3467 debug_generic_stmt (phi
);
3468 debug_generic_stmt (addr
);
3474 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); )
3476 tree stmt
= bsi_stmt (bsi
);
3478 err
|= verify_stmt (stmt
, bsi_end_p (bsi
));
3479 addr
= walk_tree (&stmt
, verify_node_sharing
, htab
, NULL
);
3482 error ("Incorrect sharing of tree nodes");
3483 debug_generic_stmt (stmt
);
3484 debug_generic_stmt (addr
);
3491 internal_error ("verify_stmts failed.");
3494 timevar_pop (TV_TREE_STMT_VERIFY
);
3498 /* Verifies that the flow information is OK. */
3501 tree_verify_flow_info (void)
3505 block_stmt_iterator bsi
;
3509 if (ENTRY_BLOCK_PTR
->stmt_list
)
3511 error ("ENTRY_BLOCK has a statement list associated with it\n");
3515 if (EXIT_BLOCK_PTR
->stmt_list
)
3517 error ("EXIT_BLOCK has a statement list associated with it\n");
3521 for (e
= EXIT_BLOCK_PTR
->pred
; e
; e
= e
->pred_next
)
3522 if (e
->flags
& EDGE_FALLTHRU
)
3524 error ("Fallthru to exit from bb %d\n", e
->src
->index
);
3530 bool found_ctrl_stmt
= false;
3532 /* Skip labels on the start of basic block. */
3533 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
3535 if (TREE_CODE (bsi_stmt (bsi
)) != LABEL_EXPR
)
3538 if (label_to_block (LABEL_EXPR_LABEL (bsi_stmt (bsi
))) != bb
)
3540 error ("Label %s to block does not match in bb %d\n",
3541 IDENTIFIER_POINTER (DECL_NAME (bsi_stmt (bsi
))),
3546 if (decl_function_context (LABEL_EXPR_LABEL (bsi_stmt (bsi
)))
3547 != current_function_decl
)
3549 error ("Label %s has incorrect context in bb %d\n",
3550 IDENTIFIER_POINTER (DECL_NAME (bsi_stmt (bsi
))),
3556 /* Verify that body of basic block BB is free of control flow. */
3557 for (; !bsi_end_p (bsi
); bsi_next (&bsi
))
3559 tree stmt
= bsi_stmt (bsi
);
3561 if (found_ctrl_stmt
)
3563 error ("Control flow in the middle of basic block %d\n",
3568 if (stmt_ends_bb_p (stmt
))
3569 found_ctrl_stmt
= true;
3571 if (TREE_CODE (stmt
) == LABEL_EXPR
)
3573 error ("Label %s in the middle of basic block %d\n",
3574 IDENTIFIER_POINTER (DECL_NAME (stmt
)),
3579 bsi
= bsi_last (bb
);
3580 if (bsi_end_p (bsi
))
3583 stmt
= bsi_stmt (bsi
);
3585 if (is_ctrl_stmt (stmt
))
3587 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
3588 if (e
->flags
& EDGE_FALLTHRU
)
3590 error ("Fallthru edge after a control statement in bb %d \n",
3596 switch (TREE_CODE (stmt
))
3602 if (TREE_CODE (COND_EXPR_THEN (stmt
)) != GOTO_EXPR
3603 || TREE_CODE (COND_EXPR_ELSE (stmt
)) != GOTO_EXPR
)
3605 error ("Structured COND_EXPR at the end of bb %d\n", bb
->index
);
3609 extract_true_false_edges_from_block (bb
, &true_edge
, &false_edge
);
3611 if (!true_edge
|| !false_edge
3612 || !(true_edge
->flags
& EDGE_TRUE_VALUE
)
3613 || !(false_edge
->flags
& EDGE_FALSE_VALUE
)
3614 || (true_edge
->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
))
3615 || (false_edge
->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
))
3616 || bb
->succ
->succ_next
->succ_next
)
3618 error ("Wrong outgoing edge flags at end of bb %d\n",
3623 if (!has_label_p (true_edge
->dest
,
3624 GOTO_DESTINATION (COND_EXPR_THEN (stmt
))))
3626 error ("`then' label does not match edge at end of bb %d\n",
3631 if (!has_label_p (false_edge
->dest
,
3632 GOTO_DESTINATION (COND_EXPR_ELSE (stmt
))))
3634 error ("`else' label does not match edge at end of bb %d\n",
3642 if (simple_goto_p (stmt
))
3644 error ("Explicit goto at end of bb %d\n", bb
->index
);
3649 /* FIXME. We should double check that the labels in the
3650 destination blocks have their address taken. */
3651 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
3652 if ((e
->flags
& (EDGE_FALLTHRU
| EDGE_TRUE_VALUE
3653 | EDGE_FALSE_VALUE
))
3654 || !(e
->flags
& EDGE_ABNORMAL
))
3656 error ("Wrong outgoing edge flags at end of bb %d\n",
3664 if (!bb
->succ
|| bb
->succ
->succ_next
3665 || (bb
->succ
->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
3666 | EDGE_TRUE_VALUE
| EDGE_FALSE_VALUE
)))
3668 error ("Wrong outgoing edge flags at end of bb %d\n", bb
->index
);
3671 if (bb
->succ
->dest
!= EXIT_BLOCK_PTR
)
3673 error ("Return edge does not point to exit in bb %d\n",
3686 vec
= SWITCH_LABELS (stmt
);
3687 n
= TREE_VEC_LENGTH (vec
);
3689 /* Mark all the destination basic blocks. */
3690 for (i
= 0; i
< n
; ++i
)
3692 tree lab
= CASE_LABEL (TREE_VEC_ELT (vec
, i
));
3693 basic_block label_bb
= label_to_block (lab
);
3695 if (label_bb
->aux
&& label_bb
->aux
!= (void *)1)
3697 label_bb
->aux
= (void *)1;
3700 /* Verify that the case labels are sorted. */
3701 prev
= TREE_VEC_ELT (vec
, 0);
3702 for (i
= 1; i
< n
- 1; ++i
)
3704 tree c
= TREE_VEC_ELT (vec
, i
);
3707 error ("Found default case not at end of case vector");
3711 if (! tree_int_cst_lt (CASE_LOW (prev
), CASE_LOW (c
)))
3713 error ("Case labels not sorted:\n ");
3714 print_generic_expr (stderr
, prev
, 0);
3715 fprintf (stderr
," is greater than ");
3716 print_generic_expr (stderr
, c
, 0);
3717 fprintf (stderr
," but comes before it.\n");
3722 if (CASE_LOW (TREE_VEC_ELT (vec
, n
- 1)))
3724 error ("No default case found at end of case vector");
3728 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
3732 error ("Extra outgoing edge %d->%d\n",
3733 bb
->index
, e
->dest
->index
);
3736 e
->dest
->aux
= (void *)2;
3737 if ((e
->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
3738 | EDGE_TRUE_VALUE
| EDGE_FALSE_VALUE
)))
3740 error ("Wrong outgoing edge flags at end of bb %d\n",
3746 /* Check that we have all of them. */
3747 for (i
= 0; i
< n
; ++i
)
3749 tree lab
= CASE_LABEL (TREE_VEC_ELT (vec
, i
));
3750 basic_block label_bb
= label_to_block (lab
);
3752 if (label_bb
->aux
!= (void *)2)
3754 error ("Missing edge %i->%i\n",
3755 bb
->index
, label_bb
->index
);
3760 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
3761 e
->dest
->aux
= (void *)0;
3768 if (dom_computed
[CDI_DOMINATORS
] >= DOM_NO_FAST_QUERY
)
3769 verify_dominators (CDI_DOMINATORS
);
3775 /* Updates phi nodes after creating forwarder block joined
3776 by edge FALLTHRU. */
3779 tree_make_forwarder_block (edge fallthru
)
3782 basic_block dummy
, bb
;
3783 tree phi
, new_phi
, var
, prev
, next
;
3785 dummy
= fallthru
->src
;
3786 bb
= fallthru
->dest
;
3788 if (!bb
->pred
->pred_next
)
3791 /* If we redirected a branch we must create new phi nodes at the
3793 for (phi
= phi_nodes (dummy
); phi
; phi
= PHI_CHAIN (phi
))
3795 var
= PHI_RESULT (phi
);
3796 new_phi
= create_phi_node (var
, bb
);
3797 SSA_NAME_DEF_STMT (var
) = new_phi
;
3798 SET_PHI_RESULT (phi
, make_ssa_name (SSA_NAME_VAR (var
), phi
));
3799 add_phi_arg (&new_phi
, PHI_RESULT (phi
), fallthru
);
3802 /* Ensure that the PHI node chain is in the same order. */
3804 for (phi
= phi_nodes (bb
); phi
; phi
= next
)
3806 next
= PHI_CHAIN (phi
);
3807 PHI_CHAIN (phi
) = prev
;
3810 set_phi_nodes (bb
, prev
);
3812 /* Add the arguments we have stored on edges. */
3813 for (e
= bb
->pred
; e
; e
= e
->pred_next
)
3818 for (phi
= phi_nodes (bb
), var
= PENDING_STMT (e
);
3820 phi
= PHI_CHAIN (phi
), var
= TREE_CHAIN (var
))
3821 add_phi_arg (&phi
, TREE_VALUE (var
), e
);
3823 PENDING_STMT (e
) = NULL
;
3828 /* Return true if basic block BB does nothing except pass control
3829 flow to another block and that we can safely insert a label at
3830 the start of the successor block. */
3833 tree_forwarder_block_p (basic_block bb
)
3835 block_stmt_iterator bsi
;
3838 /* If we have already determined that this block is not forwardable,
3839 then no further checks are necessary. */
3840 if (! bb_ann (bb
)->forwardable
)
3843 /* BB must have a single outgoing normal edge. Otherwise it can not be
3844 a forwarder block. */
3846 || bb
->succ
->succ_next
3847 || bb
->succ
->dest
== EXIT_BLOCK_PTR
3848 || (bb
->succ
->flags
& EDGE_ABNORMAL
)
3849 || bb
== ENTRY_BLOCK_PTR
)
3851 bb_ann (bb
)->forwardable
= 0;
3855 /* Successors of the entry block are not forwarders. */
3856 for (e
= ENTRY_BLOCK_PTR
->succ
; e
; e
= e
->succ_next
)
3859 bb_ann (bb
)->forwardable
= 0;
3863 /* BB can not have any PHI nodes. This could potentially be relaxed
3864 early in compilation if we re-rewrote the variables appearing in
3865 any PHI nodes in forwarder blocks. */
3868 bb_ann (bb
)->forwardable
= 0;
3872 /* Now walk through the statements. We can ignore labels, anything else
3873 means this is not a forwarder block. */
3874 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
3876 tree stmt
= bsi_stmt (bsi
);
3878 switch (TREE_CODE (stmt
))
3881 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt
)))
3886 bb_ann (bb
)->forwardable
= 0;
3895 /* Thread jumps over empty statements.
3897 This code should _not_ thread over obviously equivalent conditions
3898 as that requires nontrivial updates to the SSA graph. */
3903 edge e
, next
, last
, old
;
3904 basic_block bb
, dest
, tmp
, old_dest
, dom
;
3907 bool retval
= false;
3910 bb_ann (bb
)->forwardable
= 1;
3912 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
, EXIT_BLOCK_PTR
, next_bb
)
3914 /* Don't waste time on unreachable blocks. */
3918 /* Nor on forwarders. */
3919 if (tree_forwarder_block_p (bb
))
3922 /* This block is now part of a forwarding path, mark it as not
3923 forwardable so that we can detect loops. This bit will be
3925 bb_ann (bb
)->forwardable
= 0;
3927 /* Examine each of our block's successors to see if it is
3929 for (e
= bb
->succ
; e
; e
= next
)
3931 next
= e
->succ_next
;
3933 /* If the edge is abnormal or its destination is not
3934 forwardable, then there's nothing to do. */
3935 if ((e
->flags
& EDGE_ABNORMAL
)
3936 || !tree_forwarder_block_p (e
->dest
))
3939 /* Now walk through as many forwarder block as possible to
3940 find the ultimate destination we want to thread our jump
3942 last
= e
->dest
->succ
;
3943 bb_ann (e
->dest
)->forwardable
= 0;
3944 for (dest
= e
->dest
->succ
->dest
;
3945 tree_forwarder_block_p (dest
);
3947 dest
= dest
->succ
->dest
)
3949 /* An infinite loop detected. We redirect the edge anyway, so
3950 that the loop is shrunk into single basic block. */
3951 if (!bb_ann (dest
)->forwardable
)
3954 if (dest
->succ
->dest
== EXIT_BLOCK_PTR
)
3957 bb_ann (dest
)->forwardable
= 0;
3960 /* Reset the forwardable marks to 1. */
3963 tmp
= tmp
->succ
->dest
)
3964 bb_ann (tmp
)->forwardable
= 1;
3966 if (dest
== e
->dest
)
3969 old
= find_edge (bb
, dest
);
3972 /* If there already is an edge, check whether the values
3973 in phi nodes differ. */
3974 if (!phi_alternatives_equal (dest
, last
, old
))
3976 /* The previous block is forwarder. Redirect our jump
3977 to that target instead since we know it has no PHI
3978 nodes that will need updating. */
3981 /* That might mean that no forwarding at all is possible. */
3982 if (dest
== e
->dest
)
3985 old
= find_edge (bb
, dest
);
3989 /* Perform the redirection. */
3992 e
= redirect_edge_and_branch (e
, dest
);
3996 /* Update PHI nodes. We know that the new argument should
3997 have the same value as the argument associated with LAST.
3998 Otherwise we would have changed our target block above. */
3999 for (phi
= phi_nodes (dest
); phi
; phi
= PHI_CHAIN (phi
))
4001 arg
= phi_arg_from_edge (phi
, last
);
4004 add_phi_arg (&phi
, PHI_ARG_DEF (phi
, arg
), e
);
4008 /* Update the dominators. */
4009 if (dom_computed
[CDI_DOMINATORS
] >= DOM_CONS_OK
)
4011 /* Remove the unreachable blocks (observe that if all blocks
4012 were reachable before, only those in the path we threaded
4013 over and did not have any predecessor outside of the path
4014 become unreachable). */
4015 for (; old_dest
!= dest
; old_dest
= tmp
)
4017 tmp
= old_dest
->succ
->dest
;
4022 delete_basic_block (old_dest
);
4024 /* If the dominator of the destination was in the path, set its
4025 dominator to the start of the redirected edge. */
4026 if (get_immediate_dominator (CDI_DOMINATORS
, old_dest
) == NULL
)
4027 set_immediate_dominator (CDI_DOMINATORS
, old_dest
, bb
);
4029 /* Now proceed like if we forwarded just over one edge at a time.
4030 Algorithm for forwarding over edge A --> B then is
4033 idom (B) = idom (A);
4034 recount_idom (A); */
4036 for (; old_dest
!= dest
; old_dest
= tmp
)
4038 tmp
= old_dest
->succ
->dest
;
4040 if (get_immediate_dominator (CDI_DOMINATORS
, tmp
) == old_dest
)
4042 dom
= get_immediate_dominator (CDI_DOMINATORS
, old_dest
);
4043 set_immediate_dominator (CDI_DOMINATORS
, tmp
, dom
);
4046 dom
= recount_dominator (CDI_DOMINATORS
, old_dest
);
4047 set_immediate_dominator (CDI_DOMINATORS
, old_dest
, dom
);
4052 /* Reset the forwardable bit on our block since it's no longer in
4053 a forwarding chain path. */
4054 bb_ann (bb
)->forwardable
= 1;
4061 /* Return a non-special label in the head of basic block BLOCK.
4062 Create one if it doesn't exist. */
4065 tree_block_label (basic_block bb
)
4067 block_stmt_iterator i
, s
= bsi_start (bb
);
4071 for (i
= s
; !bsi_end_p (i
); first
= false, bsi_next (&i
))
4073 stmt
= bsi_stmt (i
);
4074 if (TREE_CODE (stmt
) != LABEL_EXPR
)
4076 label
= LABEL_EXPR_LABEL (stmt
);
4077 if (!DECL_NONLOCAL (label
))
4080 bsi_move_before (&i
, &s
);
4085 label
= create_artificial_label ();
4086 stmt
= build1 (LABEL_EXPR
, void_type_node
, label
);
4087 bsi_insert_before (&s
, stmt
, BSI_NEW_STMT
);
4092 /* Attempt to perform edge redirection by replacing a possibly complex
4093 jump instruction by a goto or by removing the jump completely.
4094 This can apply only if all edges now point to the same block. The
4095 parameters and return values are equivalent to
4096 redirect_edge_and_branch. */
4099 tree_try_redirect_by_replacing_jump (edge e
, basic_block target
)
4101 basic_block src
= e
->src
;
4103 block_stmt_iterator b
;
4106 /* Verify that all targets will be TARGET. */
4107 for (tmp
= src
->succ
; tmp
; tmp
= tmp
->succ_next
)
4108 if (tmp
->dest
!= target
&& tmp
!= e
)
4117 stmt
= bsi_stmt (b
);
4119 if (TREE_CODE (stmt
) == COND_EXPR
4120 || TREE_CODE (stmt
) == SWITCH_EXPR
)
4123 e
= ssa_redirect_edge (e
, target
);
4124 e
->flags
= EDGE_FALLTHRU
;
4132 /* Redirect E to DEST. Return NULL on failure. Otherwise, return the
4133 edge representing the redirected branch. */
4136 tree_redirect_edge_and_branch (edge e
, basic_block dest
)
4138 basic_block bb
= e
->src
;
4139 block_stmt_iterator bsi
;
4143 if (e
->flags
& (EDGE_ABNORMAL_CALL
| EDGE_EH
))
4146 if (e
->src
!= ENTRY_BLOCK_PTR
4147 && (ret
= tree_try_redirect_by_replacing_jump (e
, dest
)))
4150 if (e
->dest
== dest
)
4153 label
= tree_block_label (dest
);
4155 bsi
= bsi_last (bb
);
4156 stmt
= bsi_end_p (bsi
) ? NULL
: bsi_stmt (bsi
);
4158 switch (stmt
? TREE_CODE (stmt
) : ERROR_MARK
)
4161 stmt
= (e
->flags
& EDGE_TRUE_VALUE
4162 ? COND_EXPR_THEN (stmt
)
4163 : COND_EXPR_ELSE (stmt
));
4164 GOTO_DESTINATION (stmt
) = label
;
4168 /* No non-abnormal edges should lead from a non-simple goto, and
4169 simple ones should be represented implicitly. */
4174 tree vec
= SWITCH_LABELS (stmt
);
4175 size_t i
, n
= TREE_VEC_LENGTH (vec
);
4177 for (i
= 0; i
< n
; ++i
)
4179 tree elt
= TREE_VEC_ELT (vec
, i
);
4180 if (label_to_block (CASE_LABEL (elt
)) == e
->dest
)
4181 CASE_LABEL (elt
) = label
;
4188 e
->flags
|= EDGE_FALLTHRU
;
4192 /* Otherwise it must be a fallthru edge, and we don't need to
4193 do anything besides redirecting it. */
4194 if (!(e
->flags
& EDGE_FALLTHRU
))
4199 /* Update/insert PHI nodes as necessary. */
4201 /* Now update the edges in the CFG. */
4202 e
= ssa_redirect_edge (e
, dest
);
4208 /* Simple wrapper, as we can always redirect fallthru edges. */
4211 tree_redirect_edge_and_branch_force (edge e
, basic_block dest
)
4213 e
= tree_redirect_edge_and_branch (e
, dest
);
4221 /* Splits basic block BB after statement STMT (but at least after the
4222 labels). If STMT is NULL, BB is split just after the labels. */
4225 tree_split_block (basic_block bb
, void *stmt
)
4227 block_stmt_iterator bsi
, bsi_tgt
;
4232 new_bb
= create_empty_bb (bb
);
4234 /* Redirect the outgoing edges. */
4235 new_bb
->succ
= bb
->succ
;
4237 for (e
= new_bb
->succ
; e
; e
= e
->succ_next
)
4240 if (stmt
&& TREE_CODE ((tree
) stmt
) == LABEL_EXPR
)
4243 /* Move everything from BSI to the new basic block. */
4244 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
4246 act
= bsi_stmt (bsi
);
4247 if (TREE_CODE (act
) == LABEL_EXPR
)
4260 bsi_tgt
= bsi_start (new_bb
);
4261 while (!bsi_end_p (bsi
))
4263 act
= bsi_stmt (bsi
);
4265 bsi_insert_after (&bsi_tgt
, act
, BSI_NEW_STMT
);
4272 /* Moves basic block BB after block AFTER. */
4275 tree_move_block_after (basic_block bb
, basic_block after
)
4277 if (bb
->prev_bb
== after
)
4281 link_block (bb
, after
);
4287 /* Return true if basic_block can be duplicated. */
4290 tree_can_duplicate_bb_p (basic_block bb ATTRIBUTE_UNUSED
)
4296 /* Create a duplicate of the basic block BB. NOTE: This does not
4297 preserve SSA form. */
4300 tree_duplicate_bb (basic_block bb
)
4303 block_stmt_iterator bsi
, bsi_tgt
;
4306 v_may_def_optype v_may_defs
;
4307 v_must_def_optype v_must_defs
;
4310 new_bb
= create_empty_bb (EXIT_BLOCK_PTR
->prev_bb
);
4312 for (phi
= phi_nodes (bb
); phi
; phi
= TREE_CHAIN (phi
))
4314 mark_for_rewrite (PHI_RESULT (phi
));
4317 bsi_tgt
= bsi_start (new_bb
);
4318 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
4320 tree stmt
= bsi_stmt (bsi
);
4323 if (TREE_CODE (stmt
) == LABEL_EXPR
)
4326 /* Record the definitions. */
4327 get_stmt_operands (stmt
);
4329 defs
= STMT_DEF_OPS (stmt
);
4330 for (j
= 0; j
< NUM_DEFS (defs
); j
++)
4331 mark_for_rewrite (DEF_OP (defs
, j
));
4333 v_may_defs
= STMT_V_MAY_DEF_OPS (stmt
);
4334 for (j
= 0; j
< NUM_V_MAY_DEFS (v_may_defs
); j
++)
4335 mark_for_rewrite (V_MAY_DEF_RESULT (v_may_defs
, j
));
4337 v_must_defs
= STMT_V_MUST_DEF_OPS (stmt
);
4338 for (j
= 0; j
< NUM_V_MUST_DEFS (v_must_defs
); j
++)
4339 mark_for_rewrite (V_MUST_DEF_OP (v_must_defs
, j
));
4341 copy
= unshare_expr (stmt
);
4343 /* Copy also the virtual operands. */
4344 get_stmt_ann (copy
);
4345 copy_virtual_operands (copy
, stmt
);
4347 bsi_insert_after (&bsi_tgt
, copy
, BSI_NEW_STMT
);
4354 /* Dump FUNCTION_DECL FN to file FILE using FLAGS (see TDF_* in tree.h) */
4357 dump_function_to_file (tree fn
, FILE *file
, int flags
)
4359 tree arg
, vars
, var
;
4360 bool ignore_topmost_bind
= false, any_var
= false;
4364 fprintf (file
, "%s (", lang_hooks
.decl_printable_name (fn
, 2));
4366 arg
= DECL_ARGUMENTS (fn
);
4369 print_generic_expr (file
, arg
, dump_flags
);
4370 if (TREE_CHAIN (arg
))
4371 fprintf (file
, ", ");
4372 arg
= TREE_CHAIN (arg
);
4374 fprintf (file
, ")\n");
4376 if (flags
& TDF_RAW
)
4378 dump_node (fn
, TDF_SLIM
| flags
, file
);
4382 /* When GIMPLE is lowered, the variables are no longer available in
4383 BIND_EXPRs, so display them separately. */
4384 if (cfun
&& cfun
->unexpanded_var_list
)
4386 ignore_topmost_bind
= true;
4388 fprintf (file
, "{\n");
4389 for (vars
= cfun
->unexpanded_var_list
; vars
; vars
= TREE_CHAIN (vars
))
4391 var
= TREE_VALUE (vars
);
4393 print_generic_decl (file
, var
, flags
);
4394 fprintf (file
, "\n");
4400 if (basic_block_info
)
4402 /* Make a CFG based dump. */
4403 check_bb_profile (ENTRY_BLOCK_PTR
, file
);
4404 if (!ignore_topmost_bind
)
4405 fprintf (file
, "{\n");
4407 if (any_var
&& n_basic_blocks
)
4408 fprintf (file
, "\n");
4411 dump_generic_bb (file
, bb
, 2, flags
);
4413 fprintf (file
, "}\n");
4414 check_bb_profile (EXIT_BLOCK_PTR
, file
);
4420 /* Make a tree based dump. */
4421 chain
= DECL_SAVED_TREE (fn
);
4423 if (TREE_CODE (chain
) == BIND_EXPR
)
4425 if (ignore_topmost_bind
)
4427 chain
= BIND_EXPR_BODY (chain
);
4435 if (!ignore_topmost_bind
)
4436 fprintf (file
, "{\n");
4441 fprintf (file
, "\n");
4443 print_generic_stmt_indented (file
, chain
, flags
, indent
);
4444 if (ignore_topmost_bind
)
4445 fprintf (file
, "}\n");
4448 fprintf (file
, "\n\n");
4452 /* Pretty print of the loops intermediate representation. */
4453 static void print_loop (FILE *, struct loop
*, int);
4454 static void print_pred_bbs (FILE *, edge
);
4455 static void print_succ_bbs (FILE *, edge
);
4458 /* Print the predecessors indexes of edge E on FILE. */
4461 print_pred_bbs (FILE *file
, edge e
)
4466 else if (e
->pred_next
== NULL
)
4467 fprintf (file
, "bb_%d", e
->src
->index
);
4471 fprintf (file
, "bb_%d, ", e
->src
->index
);
4472 print_pred_bbs (file
, e
->pred_next
);
4477 /* Print the successors indexes of edge E on FILE. */
4480 print_succ_bbs (FILE *file
, edge e
)
4484 else if (e
->succ_next
== NULL
)
4485 fprintf (file
, "bb_%d", e
->dest
->index
);
4488 fprintf (file
, "bb_%d, ", e
->dest
->index
);
4489 print_succ_bbs (file
, e
->succ_next
);
4494 /* Pretty print LOOP on FILE, indented INDENT spaces. */
4497 print_loop (FILE *file
, struct loop
*loop
, int indent
)
4505 s_indent
= (char *) alloca ((size_t) indent
+ 1);
4506 memset ((void *) s_indent
, ' ', (size_t) indent
);
4507 s_indent
[indent
] = '\0';
4509 /* Print the loop's header. */
4510 fprintf (file
, "%sloop_%d\n", s_indent
, loop
->num
);
4512 /* Print the loop's body. */
4513 fprintf (file
, "%s{\n", s_indent
);
4515 if (bb
->loop_father
== loop
)
4517 /* Print the basic_block's header. */
4518 fprintf (file
, "%s bb_%d (preds = {", s_indent
, bb
->index
);
4519 print_pred_bbs (file
, bb
->pred
);
4520 fprintf (file
, "}, succs = {");
4521 print_succ_bbs (file
, bb
->succ
);
4522 fprintf (file
, "})\n");
4524 /* Print the basic_block's body. */
4525 fprintf (file
, "%s {\n", s_indent
);
4526 tree_dump_bb (bb
, file
, indent
+ 4);
4527 fprintf (file
, "%s }\n", s_indent
);
4530 print_loop (file
, loop
->inner
, indent
+ 2);
4531 fprintf (file
, "%s}\n", s_indent
);
4532 print_loop (file
, loop
->next
, indent
);
4536 /* Follow a CFG edge from the entry point of the program, and on entry
4537 of a loop, pretty print the loop structure on FILE. */
4540 print_loop_ir (FILE *file
)
4544 bb
= BASIC_BLOCK (0);
4545 if (bb
&& bb
->loop_father
)
4546 print_loop (file
, bb
->loop_father
, 0);
4550 /* Debugging loops structure at tree level. */
4553 debug_loop_ir (void)
4555 print_loop_ir (stderr
);
4559 /* Return true if BB ends with a call, possibly followed by some
4560 instructions that must stay with the call. Return false,
4564 tree_block_ends_with_call_p (basic_block bb
)
4566 block_stmt_iterator bsi
= bsi_last (bb
);
4567 return get_call_expr_in (bsi_stmt (bsi
)) != NULL
;
4571 /* Return true if BB ends with a conditional branch. Return false,
4575 tree_block_ends_with_condjump_p (basic_block bb
)
4577 tree stmt
= tsi_stmt (bsi_last (bb
).tsi
);
4578 return (TREE_CODE (stmt
) == COND_EXPR
);
4582 /* Return true if we need to add fake edge to exit at statement T.
4583 Helper function for tree_flow_call_edges_add. */
4586 need_fake_edge_p (tree t
)
4590 /* NORETURN and LONGJMP calls already have an edge to exit.
4591 CONST, PURE and ALWAYS_RETURN calls do not need one.
4592 We don't currently check for CONST and PURE here, although
4593 it would be a good idea, because those attributes are
4594 figured out from the RTL in mark_constant_function, and
4595 the counter incrementation code from -fprofile-arcs
4596 leads to different results from -fbranch-probabilities. */
4597 call
= get_call_expr_in (t
);
4599 && !(call_expr_flags (call
) &
4600 (ECF_NORETURN
| ECF_LONGJMP
| ECF_ALWAYS_RETURN
)))
4603 if (TREE_CODE (t
) == ASM_EXPR
4604 && (ASM_VOLATILE_P (t
) || ASM_INPUT_P (t
)))
4611 /* Add fake edges to the function exit for any non constant and non
4612 noreturn calls, volatile inline assembly in the bitmap of blocks
4613 specified by BLOCKS or to the whole CFG if BLOCKS is zero. Return
4614 the number of blocks that were split.
4616 The goal is to expose cases in which entering a basic block does
4617 not imply that all subsequent instructions must be executed. */
4620 tree_flow_call_edges_add (sbitmap blocks
)
4623 int blocks_split
= 0;
4624 int last_bb
= last_basic_block
;
4625 bool check_last_block
= false;
4627 if (n_basic_blocks
== 0)
4631 check_last_block
= true;
4633 check_last_block
= TEST_BIT (blocks
, EXIT_BLOCK_PTR
->prev_bb
->index
);
4635 /* In the last basic block, before epilogue generation, there will be
4636 a fallthru edge to EXIT. Special care is required if the last insn
4637 of the last basic block is a call because make_edge folds duplicate
4638 edges, which would result in the fallthru edge also being marked
4639 fake, which would result in the fallthru edge being removed by
4640 remove_fake_edges, which would result in an invalid CFG.
4642 Moreover, we can't elide the outgoing fake edge, since the block
4643 profiler needs to take this into account in order to solve the minimal
4644 spanning tree in the case that the call doesn't return.
4646 Handle this by adding a dummy instruction in a new last basic block. */
4647 if (check_last_block
)
4649 basic_block bb
= EXIT_BLOCK_PTR
->prev_bb
;
4650 block_stmt_iterator bsi
= bsi_last (bb
);
4652 if (!bsi_end_p (bsi
))
4655 if (need_fake_edge_p (t
))
4659 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
4660 if (e
->dest
== EXIT_BLOCK_PTR
)
4662 bsi_insert_on_edge (e
, build_empty_stmt ());
4663 bsi_commit_edge_inserts ((int *)NULL
);
4669 /* Now add fake edges to the function exit for any non constant
4670 calls since there is no way that we can determine if they will
4672 for (i
= 0; i
< last_bb
; i
++)
4674 basic_block bb
= BASIC_BLOCK (i
);
4675 block_stmt_iterator bsi
;
4676 tree stmt
, last_stmt
;
4681 if (blocks
&& !TEST_BIT (blocks
, i
))
4684 bsi
= bsi_last (bb
);
4685 if (!bsi_end_p (bsi
))
4687 last_stmt
= bsi_stmt (bsi
);
4690 stmt
= bsi_stmt (bsi
);
4691 if (need_fake_edge_p (stmt
))
4694 /* The handling above of the final block before the
4695 epilogue should be enough to verify that there is
4696 no edge to the exit block in CFG already.
4697 Calling make_edge in such case would cause us to
4698 mark that edge as fake and remove it later. */
4699 #ifdef ENABLE_CHECKING
4700 if (stmt
== last_stmt
)
4701 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
4702 if (e
->dest
== EXIT_BLOCK_PTR
)
4706 /* Note that the following may create a new basic block
4707 and renumber the existing basic blocks. */
4708 if (stmt
!= last_stmt
)
4710 e
= split_block (bb
, stmt
);
4714 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
4718 while (!bsi_end_p (bsi
));
4723 verify_flow_info ();
4725 return blocks_split
;
4729 tree_purge_dead_eh_edges (basic_block bb
)
4731 bool changed
= false;
4733 tree stmt
= last_stmt (bb
);
4735 if (stmt
&& tree_can_throw_internal (stmt
))
4738 for (e
= bb
->succ
; e
; e
= next
)
4740 next
= e
->succ_next
;
4741 if (e
->flags
& EDGE_EH
)
4743 ssa_remove_edge (e
);
4752 tree_purge_all_dead_eh_edges (bitmap blocks
)
4754 bool changed
= false;
4757 EXECUTE_IF_SET_IN_BITMAP (blocks
, 0, i
,
4758 { changed
|= tree_purge_dead_eh_edges (BASIC_BLOCK (i
)); });
4763 struct cfg_hooks tree_cfg_hooks
= {
4765 tree_verify_flow_info
,
4766 tree_dump_bb
, /* dump_bb */
4767 create_bb
, /* create_basic_block */
4768 tree_redirect_edge_and_branch
,/* redirect_edge_and_branch */
4769 tree_redirect_edge_and_branch_force
,/* redirect_edge_and_branch_force */
4770 remove_bb
, /* delete_basic_block */
4771 tree_split_block
, /* split_block */
4772 tree_move_block_after
, /* move_block_after */
4773 tree_can_merge_blocks_p
, /* can_merge_blocks_p */
4774 tree_merge_blocks
, /* merge_blocks */
4775 tree_predict_edge
, /* predict_edge */
4776 tree_predicted_by_p
, /* predicted_by_p */
4777 tree_can_duplicate_bb_p
, /* can_duplicate_block_p */
4778 tree_duplicate_bb
, /* duplicate_block */
4779 tree_split_edge
, /* split_edge */
4780 tree_make_forwarder_block
, /* make_forward_block */
4781 NULL
, /* tidy_fallthru_edge */
4782 tree_block_ends_with_call_p
, /* block_ends_with_call_p */
4783 tree_block_ends_with_condjump_p
, /* block_ends_with_condjump_p */
4784 tree_flow_call_edges_add
/* flow_call_edges_add */
4788 /* Split all critical edges. */
4791 split_critical_edges (void)
4798 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
4799 if (EDGE_CRITICAL_P (e
) && !(e
->flags
& EDGE_ABNORMAL
))
4806 struct tree_opt_pass pass_split_crit_edges
=
4808 "crited", /* name */
4810 split_critical_edges
, /* execute */
4813 0, /* static_pass_number */
4814 TV_TREE_SPLIT_EDGES
, /* tv_id */
4815 PROP_cfg
, /* properties required */
4816 PROP_no_crit_edges
, /* properties_provided */
4817 0, /* properties_destroyed */
4818 0, /* todo_flags_start */
4819 TODO_dump_func
, /* todo_flags_finish */
4823 /* Return EXP if it is a valid GIMPLE rvalue, else gimplify it into
4824 a temporary, make sure and register it to be renamed if necessary,
4825 and finally return the temporary. Put the statements to compute
4826 EXP before the current statement in BSI. */
4829 gimplify_val (block_stmt_iterator
*bsi
, tree type
, tree exp
)
4831 tree t
, new_stmt
, orig_stmt
;
4833 if (is_gimple_val (exp
))
4836 t
= make_rename_temp (type
, NULL
);
4837 new_stmt
= build (MODIFY_EXPR
, type
, t
, exp
);
4839 orig_stmt
= bsi_stmt (*bsi
);
4840 SET_EXPR_LOCUS (new_stmt
, EXPR_LOCUS (orig_stmt
));
4841 TREE_BLOCK (new_stmt
) = TREE_BLOCK (orig_stmt
);
4843 bsi_insert_before (bsi
, new_stmt
, BSI_SAME_STMT
);
4848 /* Build a ternary operation and gimplify it. Emit code before BSI.
4849 Return the gimple_val holding the result. */
4852 gimplify_build3 (block_stmt_iterator
*bsi
, enum tree_code code
,
4853 tree type
, tree a
, tree b
, tree c
)
4857 ret
= fold (build3 (code
, type
, a
, b
, c
));
4860 return gimplify_val (bsi
, type
, ret
);
4863 /* Build a binary operation and gimplify it. Emit code before BSI.
4864 Return the gimple_val holding the result. */
4867 gimplify_build2 (block_stmt_iterator
*bsi
, enum tree_code code
,
4868 tree type
, tree a
, tree b
)
4872 ret
= fold (build2 (code
, type
, a
, b
));
4875 return gimplify_val (bsi
, type
, ret
);
4878 /* Build a unary operation and gimplify it. Emit code before BSI.
4879 Return the gimple_val holding the result. */
4882 gimplify_build1 (block_stmt_iterator
*bsi
, enum tree_code code
, tree type
,
4887 ret
= fold (build1 (code
, type
, a
));
4890 return gimplify_val (bsi
, type
, ret
);
4895 /* Emit return warnings. */
4898 execute_warn_function_return (void)
4900 #ifdef USE_MAPPED_LOCATION
4901 source_location location
;
4908 if (warn_missing_noreturn
4909 && !TREE_THIS_VOLATILE (cfun
->decl
)
4910 && EXIT_BLOCK_PTR
->pred
== NULL
4911 && !lang_hooks
.function
.missing_noreturn_ok_p (cfun
->decl
))
4912 warning ("%Jfunction might be possible candidate for attribute `noreturn'",
4915 /* If we have a path to EXIT, then we do return. */
4916 if (TREE_THIS_VOLATILE (cfun
->decl
)
4917 && EXIT_BLOCK_PTR
->pred
!= NULL
)
4919 #ifdef USE_MAPPED_LOCATION
4920 location
= UNKNOWN_LOCATION
;
4924 for (e
= EXIT_BLOCK_PTR
->pred
; e
; e
= e
->pred_next
)
4926 last
= last_stmt (e
->src
);
4927 if (TREE_CODE (last
) == RETURN_EXPR
4928 #ifdef USE_MAPPED_LOCATION
4929 && (location
= EXPR_LOCATION (last
)) != UNKNOWN_LOCATION
)
4931 && (locus
= EXPR_LOCUS (last
)) != NULL
)
4935 #ifdef USE_MAPPED_LOCATION
4936 if (location
== UNKNOWN_LOCATION
)
4937 location
= cfun
->function_end_locus
;
4938 warning ("%H`noreturn' function does return", &location
);
4941 locus
= &cfun
->function_end_locus
;
4942 warning ("%H`noreturn' function does return", locus
);
4946 /* If we see "return;" in some basic block, then we do reach the end
4947 without returning a value. */
4948 else if (warn_return_type
4949 && EXIT_BLOCK_PTR
->pred
!= NULL
4950 && !VOID_TYPE_P (TREE_TYPE (TREE_TYPE (cfun
->decl
))))
4952 for (e
= EXIT_BLOCK_PTR
->pred
; e
; e
= e
->pred_next
)
4954 tree last
= last_stmt (e
->src
);
4955 if (TREE_CODE (last
) == RETURN_EXPR
4956 && TREE_OPERAND (last
, 0) == NULL
)
4958 #ifdef USE_MAPPED_LOCATION
4959 location
= EXPR_LOCATION (last
);
4960 if (location
== UNKNOWN_LOCATION
)
4961 location
= cfun
->function_end_locus
;
4962 warning ("%Hcontrol reaches end of non-void function", &location
);
4964 locus
= EXPR_LOCUS (last
);
4966 locus
= &cfun
->function_end_locus
;
4967 warning ("%Hcontrol reaches end of non-void function", locus
);
4976 /* Given a basic block B which ends with a conditional and has
4977 precisely two successors, determine which of the edges is taken if
4978 the conditional is true and which is taken if the conditional is
4979 false. Set TRUE_EDGE and FALSE_EDGE appropriately. */
4982 extract_true_false_edges_from_block (basic_block b
,
4988 if (e
->flags
& EDGE_TRUE_VALUE
)
4991 *false_edge
= e
->succ_next
;
4996 *true_edge
= e
->succ_next
;
5000 struct tree_opt_pass pass_warn_function_return
=
5004 execute_warn_function_return
, /* execute */
5007 0, /* static_pass_number */
5009 PROP_cfg
, /* properties_required */
5010 0, /* properties_provided */
5011 0, /* properties_destroyed */
5012 0, /* todo_flags_start */
5013 0 /* todo_flags_finish */
5016 #include "gt-tree-cfg.h"