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 Likewise for the value it was previously set to. Note that we only
1743 consider values that are either a VAR_DECL or PARM_DECL so we
1744 can test for conflict very simply. */
1745 if (TREE_CODE (stmt
) == ASM_EXPR
1746 || (TREE_CODE (stmt
) == MODIFY_EXPR
1747 && (TREE_OPERAND (stmt
, 0) == var
1748 || TREE_OPERAND (stmt
, 0) == val
)))
1756 /* A CFG-aware version of remove_useless_stmts. */
1759 cfg_remove_useless_stmts (void)
1763 #ifdef ENABLE_CHECKING
1764 verify_flow_info ();
1769 cfg_remove_useless_stmts_bb (bb
);
1774 /* Remove PHI nodes associated with basic block BB and all edges out of BB. */
1777 remove_phi_nodes_and_edges_for_unreachable_block (basic_block bb
)
1781 /* Since this block is no longer reachable, we can just delete all
1782 of its PHI nodes. */
1783 phi
= phi_nodes (bb
);
1786 tree next
= PHI_CHAIN (phi
);
1787 remove_phi_node (phi
, NULL_TREE
, bb
);
1791 /* Remove edges to BB's successors. */
1792 while (bb
->succ
!= NULL
)
1793 ssa_remove_edge (bb
->succ
);
1797 /* Remove statements of basic block BB. */
1800 remove_bb (basic_block bb
)
1802 block_stmt_iterator i
;
1803 source_locus loc
= 0;
1807 fprintf (dump_file
, "Removing basic block %d\n", bb
->index
);
1808 if (dump_flags
& TDF_DETAILS
)
1810 dump_bb (bb
, dump_file
, 0);
1811 fprintf (dump_file
, "\n");
1815 /* Remove all the instructions in the block. */
1816 for (i
= bsi_start (bb
); !bsi_end_p (i
); bsi_remove (&i
))
1818 tree stmt
= bsi_stmt (i
);
1820 set_bb_for_stmt (stmt
, NULL
);
1822 /* Don't warn for removed gotos. Gotos are often removed due to
1823 jump threading, thus resulting in bogus warnings. Not great,
1824 since this way we lose warnings for gotos in the original
1825 program that are indeed unreachable. */
1826 if (TREE_CODE (stmt
) != GOTO_EXPR
&& EXPR_HAS_LOCATION (stmt
) && !loc
)
1827 #ifdef USE_MAPPED_LOCATION
1828 loc
= EXPR_LOCATION (stmt
);
1830 loc
= EXPR_LOCUS (stmt
);
1834 /* If requested, give a warning that the first statement in the
1835 block is unreachable. We walk statements backwards in the
1836 loop above, so the last statement we process is the first statement
1838 if (warn_notreached
&& loc
)
1839 #ifdef USE_MAPPED_LOCATION
1840 warning ("%Hwill never be executed", &loc
);
1842 warning ("%Hwill never be executed", loc
);
1845 remove_phi_nodes_and_edges_for_unreachable_block (bb
);
1849 /* Examine BB to determine if it is a forwarding block (a block which only
1850 transfers control to a new destination). If BB is a forwarding block,
1851 then return the edge leading to the ultimate destination. */
1854 tree_block_forwards_to (basic_block bb
)
1856 block_stmt_iterator bsi
;
1857 bb_ann_t ann
= bb_ann (bb
);
1860 /* If this block is not forwardable, then avoid useless work. */
1861 if (! ann
->forwardable
)
1864 /* Set this block to not be forwardable. This prevents infinite loops since
1865 any block currently under examination is considered non-forwardable. */
1866 ann
->forwardable
= 0;
1868 /* No forwarding is possible if this block is a special block (ENTRY/EXIT),
1869 this block has more than one successor, this block's single successor is
1870 reached via an abnormal edge, this block has phi nodes, or this block's
1871 single successor has phi nodes. */
1872 if (bb
== EXIT_BLOCK_PTR
1873 || bb
== ENTRY_BLOCK_PTR
1875 || bb
->succ
->succ_next
1876 || bb
->succ
->dest
== EXIT_BLOCK_PTR
1877 || (bb
->succ
->flags
& EDGE_ABNORMAL
) != 0
1879 || phi_nodes (bb
->succ
->dest
))
1882 /* Walk past any labels at the start of this block. */
1883 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
1885 stmt
= bsi_stmt (bsi
);
1886 if (TREE_CODE (stmt
) != LABEL_EXPR
)
1890 /* If we reached the end of this block we may be able to optimize this
1892 if (bsi_end_p (bsi
))
1896 /* Recursive call to pick up chains of forwarding blocks. */
1897 dest
= tree_block_forwards_to (bb
->succ
->dest
);
1899 /* If none found, we forward to bb->succ at minimum. */
1903 ann
->forwardable
= 1;
1907 /* No forwarding possible. */
1912 /* Try to remove superfluous control structures. */
1915 cleanup_control_flow (void)
1918 block_stmt_iterator bsi
;
1919 bool retval
= false;
1924 bsi
= bsi_last (bb
);
1926 if (bsi_end_p (bsi
))
1929 stmt
= bsi_stmt (bsi
);
1930 if (TREE_CODE (stmt
) == COND_EXPR
1931 || TREE_CODE (stmt
) == SWITCH_EXPR
)
1932 retval
|= cleanup_control_expr_graph (bb
, bsi
);
1938 /* Disconnect an unreachable block in the control expression starting
1942 cleanup_control_expr_graph (basic_block bb
, block_stmt_iterator bsi
)
1945 bool retval
= false;
1946 tree expr
= bsi_stmt (bsi
), val
;
1948 if (bb
->succ
->succ_next
)
1952 switch (TREE_CODE (expr
))
1955 val
= COND_EXPR_COND (expr
);
1959 val
= SWITCH_COND (expr
);
1960 if (TREE_CODE (val
) != INTEGER_CST
)
1968 taken_edge
= find_taken_edge (bb
, val
);
1972 /* Remove all the edges except the one that is always executed. */
1973 for (e
= bb
->succ
; e
; e
= next
)
1975 next
= e
->succ_next
;
1976 if (e
!= taken_edge
)
1978 taken_edge
->probability
+= e
->probability
;
1979 taken_edge
->count
+= e
->count
;
1980 ssa_remove_edge (e
);
1984 if (taken_edge
->probability
> REG_BR_PROB_BASE
)
1985 taken_edge
->probability
= REG_BR_PROB_BASE
;
1988 taken_edge
= bb
->succ
;
1991 taken_edge
->flags
= EDGE_FALLTHRU
;
1993 /* We removed some paths from the cfg. */
1994 if (dom_computed
[CDI_DOMINATORS
] >= DOM_CONS_OK
)
1995 dom_computed
[CDI_DOMINATORS
] = DOM_CONS_OK
;
2001 /* Given a control block BB and a predicate VAL, return the edge that
2002 will be taken out of the block. If VAL does not match a unique
2003 edge, NULL is returned. */
2006 find_taken_edge (basic_block bb
, tree val
)
2010 stmt
= last_stmt (bb
);
2012 #if defined ENABLE_CHECKING
2013 if (stmt
== NULL_TREE
|| !is_ctrl_stmt (stmt
))
2017 /* If VAL is a predicate of the form N RELOP N, where N is an
2018 SSA_NAME, we can always determine its truth value (except when
2019 doing floating point comparisons that may involve NaNs). */
2021 && TREE_CODE_CLASS (TREE_CODE (val
)) == '<'
2022 && TREE_OPERAND (val
, 0) == TREE_OPERAND (val
, 1)
2023 && TREE_CODE (TREE_OPERAND (val
, 0)) == SSA_NAME
2024 && (TREE_CODE (TREE_TYPE (TREE_OPERAND (val
, 0))) != REAL_TYPE
2025 || !HONOR_NANS (TYPE_MODE (TREE_TYPE (TREE_OPERAND (val
, 0))))))
2027 enum tree_code code
= TREE_CODE (val
);
2029 if (code
== EQ_EXPR
|| code
== LE_EXPR
|| code
== GE_EXPR
)
2030 val
= boolean_true_node
;
2031 else if (code
== LT_EXPR
|| code
== GT_EXPR
|| code
== NE_EXPR
)
2032 val
= boolean_false_node
;
2035 /* If VAL is not a constant, we can't determine which edge might
2037 if (val
== NULL
|| !really_constant_p (val
))
2040 if (TREE_CODE (stmt
) == COND_EXPR
)
2041 return find_taken_edge_cond_expr (bb
, val
);
2043 if (TREE_CODE (stmt
) == SWITCH_EXPR
)
2044 return find_taken_edge_switch_expr (bb
, val
);
2050 /* Given a constant value VAL and the entry block BB to a COND_EXPR
2051 statement, determine which of the two edges will be taken out of the
2052 block. Return NULL if either edge may be taken. */
2055 find_taken_edge_cond_expr (basic_block bb
, tree val
)
2057 edge true_edge
, false_edge
;
2059 extract_true_false_edges_from_block (bb
, &true_edge
, &false_edge
);
2061 /* If both edges of the branch lead to the same basic block, it doesn't
2062 matter which edge is taken. */
2063 if (true_edge
->dest
== false_edge
->dest
)
2066 /* Otherwise, try to determine which branch of the if() will be taken.
2067 If VAL is a constant but it can't be reduced to a 0 or a 1, then
2068 we don't really know which edge will be taken at runtime. This
2069 may happen when comparing addresses (e.g., if (&var1 == 4)). */
2070 if (integer_nonzerop (val
))
2072 else if (integer_zerop (val
))
2079 /* Given a constant value VAL and the entry block BB to a SWITCH_EXPR
2080 statement, determine which edge will be taken out of the block. Return
2081 NULL if any edge may be taken. */
2084 find_taken_edge_switch_expr (basic_block bb
, tree val
)
2086 tree switch_expr
, taken_case
;
2087 basic_block dest_bb
;
2090 if (TREE_CODE (val
) != INTEGER_CST
)
2093 switch_expr
= last_stmt (bb
);
2094 taken_case
= find_case_label_for_value (switch_expr
, val
);
2095 dest_bb
= label_to_block (CASE_LABEL (taken_case
));
2097 e
= find_edge (bb
, dest_bb
);
2104 /* Return the CASE_LABEL_EXPR that SWITCH_EXPR will take for VAL.
2105 We can make optimal use here of the fact that the case labels are
2106 sorted: We can do a binary search for a case matching VAL. */
2109 find_case_label_for_value (tree switch_expr
, tree val
)
2111 tree vec
= SWITCH_LABELS (switch_expr
);
2112 size_t low
, high
, n
= TREE_VEC_LENGTH (vec
);
2113 tree default_case
= TREE_VEC_ELT (vec
, n
- 1);
2115 for (low
= -1, high
= n
- 1; high
- low
> 1; )
2117 size_t i
= (high
+ low
) / 2;
2118 tree t
= TREE_VEC_ELT (vec
, i
);
2121 /* Cache the result of comparing CASE_LOW and val. */
2122 cmp
= tree_int_cst_compare (CASE_LOW (t
), val
);
2129 if (CASE_HIGH (t
) == NULL
)
2131 /* A singe-valued case label. */
2137 /* A case range. We can only handle integer ranges. */
2138 if (cmp
<= 0 && tree_int_cst_compare (CASE_HIGH (t
), val
) >= 0)
2143 return default_case
;
2147 /* If all the PHI nodes in DEST have alternatives for E1 and E2 and
2148 those alternatives are equal in each of the PHI nodes, then return
2149 true, else return false. */
2152 phi_alternatives_equal (basic_block dest
, edge e1
, edge e2
)
2154 tree phi
, val1
, val2
;
2157 for (phi
= phi_nodes (dest
); phi
; phi
= PHI_CHAIN (phi
))
2159 n1
= phi_arg_from_edge (phi
, e1
);
2160 n2
= phi_arg_from_edge (phi
, e2
);
2162 #ifdef ENABLE_CHECKING
2163 if (n1
< 0 || n2
< 0)
2167 val1
= PHI_ARG_DEF (phi
, n1
);
2168 val2
= PHI_ARG_DEF (phi
, n2
);
2170 if (!operand_equal_p (val1
, val2
, 0))
2178 /*---------------------------------------------------------------------------
2180 ---------------------------------------------------------------------------*/
2182 /* Dump tree-specific information of block BB to file OUTF. */
2185 tree_dump_bb (basic_block bb
, FILE *outf
, int indent
)
2187 dump_generic_bb (outf
, bb
, indent
, TDF_VOPS
);
2191 /* Dump a basic block on stderr. */
2194 debug_tree_bb (basic_block bb
)
2196 dump_bb (bb
, stderr
, 0);
2200 /* Dump basic block with index N on stderr. */
2203 debug_tree_bb_n (int n
)
2205 debug_tree_bb (BASIC_BLOCK (n
));
2206 return BASIC_BLOCK (n
);
2210 /* Dump the CFG on stderr.
2212 FLAGS are the same used by the tree dumping functions
2213 (see TDF_* in tree.h). */
2216 debug_tree_cfg (int flags
)
2218 dump_tree_cfg (stderr
, flags
);
2222 /* Dump the program showing basic block boundaries on the given FILE.
2224 FLAGS are the same used by the tree dumping functions (see TDF_* in
2228 dump_tree_cfg (FILE *file
, int flags
)
2230 if (flags
& TDF_DETAILS
)
2232 const char *funcname
2233 = lang_hooks
.decl_printable_name (current_function_decl
, 2);
2236 fprintf (file
, ";; Function %s\n\n", funcname
);
2237 fprintf (file
, ";; \n%d basic blocks, %d edges, last basic block %d.\n\n",
2238 n_basic_blocks
, n_edges
, last_basic_block
);
2240 brief_dump_cfg (file
);
2241 fprintf (file
, "\n");
2244 if (flags
& TDF_STATS
)
2245 dump_cfg_stats (file
);
2247 dump_function_to_file (current_function_decl
, file
, flags
| TDF_BLOCKS
);
2251 /* Dump CFG statistics on FILE. */
2254 dump_cfg_stats (FILE *file
)
2256 static long max_num_merged_labels
= 0;
2257 unsigned long size
, total
= 0;
2260 const char * const fmt_str
= "%-30s%-13s%12s\n";
2261 const char * const fmt_str_1
= "%-30s%13d%11lu%c\n";
2262 const char * const fmt_str_3
= "%-43s%11lu%c\n";
2263 const char *funcname
2264 = lang_hooks
.decl_printable_name (current_function_decl
, 2);
2267 fprintf (file
, "\nCFG Statistics for %s\n\n", funcname
);
2269 fprintf (file
, "---------------------------------------------------------\n");
2270 fprintf (file
, fmt_str
, "", " Number of ", "Memory");
2271 fprintf (file
, fmt_str
, "", " instances ", "used ");
2272 fprintf (file
, "---------------------------------------------------------\n");
2274 size
= n_basic_blocks
* sizeof (struct basic_block_def
);
2276 fprintf (file
, fmt_str_1
, "Basic blocks", n_basic_blocks
,
2277 SCALE (size
), LABEL (size
));
2283 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
2286 size
= n_edges
* sizeof (struct edge_def
);
2288 fprintf (file
, fmt_str_1
, "Edges", n_edges
, SCALE (size
), LABEL (size
));
2290 size
= n_basic_blocks
* sizeof (struct bb_ann_d
);
2292 fprintf (file
, fmt_str_1
, "Basic block annotations", n_basic_blocks
,
2293 SCALE (size
), LABEL (size
));
2295 fprintf (file
, "---------------------------------------------------------\n");
2296 fprintf (file
, fmt_str_3
, "Total memory used by CFG data", SCALE (total
),
2298 fprintf (file
, "---------------------------------------------------------\n");
2299 fprintf (file
, "\n");
2301 if (cfg_stats
.num_merged_labels
> max_num_merged_labels
)
2302 max_num_merged_labels
= cfg_stats
.num_merged_labels
;
2304 fprintf (file
, "Coalesced label blocks: %ld (Max so far: %ld)\n",
2305 cfg_stats
.num_merged_labels
, max_num_merged_labels
);
2307 fprintf (file
, "\n");
2311 /* Dump CFG statistics on stderr. Keep extern so that it's always
2312 linked in the final executable. */
2315 debug_cfg_stats (void)
2317 dump_cfg_stats (stderr
);
2321 /* Dump the flowgraph to a .vcg FILE. */
2324 tree_cfg2vcg (FILE *file
)
2328 const char *funcname
2329 = lang_hooks
.decl_printable_name (current_function_decl
, 2);
2331 /* Write the file header. */
2332 fprintf (file
, "graph: { title: \"%s\"\n", funcname
);
2333 fprintf (file
, "node: { title: \"ENTRY\" label: \"ENTRY\" }\n");
2334 fprintf (file
, "node: { title: \"EXIT\" label: \"EXIT\" }\n");
2336 /* Write blocks and edges. */
2337 for (e
= ENTRY_BLOCK_PTR
->succ
; e
; e
= e
->succ_next
)
2339 fprintf (file
, "edge: { sourcename: \"ENTRY\" targetname: \"%d\"",
2342 if (e
->flags
& EDGE_FAKE
)
2343 fprintf (file
, " linestyle: dotted priority: 10");
2345 fprintf (file
, " linestyle: solid priority: 100");
2347 fprintf (file
, " }\n");
2353 enum tree_code head_code
, end_code
;
2354 const char *head_name
, *end_name
;
2357 tree first
= first_stmt (bb
);
2358 tree last
= last_stmt (bb
);
2362 head_code
= TREE_CODE (first
);
2363 head_name
= tree_code_name
[head_code
];
2364 head_line
= get_lineno (first
);
2367 head_name
= "no-statement";
2371 end_code
= TREE_CODE (last
);
2372 end_name
= tree_code_name
[end_code
];
2373 end_line
= get_lineno (last
);
2376 end_name
= "no-statement";
2378 fprintf (file
, "node: { title: \"%d\" label: \"#%d\\n%s (%d)\\n%s (%d)\"}\n",
2379 bb
->index
, bb
->index
, head_name
, head_line
, end_name
,
2382 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
2384 if (e
->dest
== EXIT_BLOCK_PTR
)
2385 fprintf (file
, "edge: { sourcename: \"%d\" targetname: \"EXIT\"", bb
->index
);
2387 fprintf (file
, "edge: { sourcename: \"%d\" targetname: \"%d\"", bb
->index
, e
->dest
->index
);
2389 if (e
->flags
& EDGE_FAKE
)
2390 fprintf (file
, " priority: 10 linestyle: dotted");
2392 fprintf (file
, " priority: 100 linestyle: solid");
2394 fprintf (file
, " }\n");
2397 if (bb
->next_bb
!= EXIT_BLOCK_PTR
)
2401 fputs ("}\n\n", file
);
2406 /*---------------------------------------------------------------------------
2407 Miscellaneous helpers
2408 ---------------------------------------------------------------------------*/
2410 /* Return true if T represents a stmt that always transfers control. */
2413 is_ctrl_stmt (tree t
)
2415 return (TREE_CODE (t
) == COND_EXPR
2416 || TREE_CODE (t
) == SWITCH_EXPR
2417 || TREE_CODE (t
) == GOTO_EXPR
2418 || TREE_CODE (t
) == RETURN_EXPR
2419 || TREE_CODE (t
) == RESX_EXPR
);
2423 /* Return true if T is a statement that may alter the flow of control
2424 (e.g., a call to a non-returning function). */
2427 is_ctrl_altering_stmt (tree t
)
2431 #if defined ENABLE_CHECKING
2436 call
= get_call_expr_in (t
);
2439 /* A non-pure/const CALL_EXPR alters flow control if the current
2440 function has nonlocal labels. */
2441 if (TREE_SIDE_EFFECTS (call
) && current_function_has_nonlocal_label
)
2444 /* A CALL_EXPR also alters control flow if it does not return. */
2445 if (call_expr_flags (call
) & (ECF_NORETURN
| ECF_LONGJMP
))
2449 /* If a statement can throw, it alters control flow. */
2450 return tree_can_throw_internal (t
);
2454 /* Return true if T is a computed goto. */
2457 computed_goto_p (tree t
)
2459 return (TREE_CODE (t
) == GOTO_EXPR
2460 && TREE_CODE (GOTO_DESTINATION (t
)) != LABEL_DECL
);
2464 /* Checks whether EXPR is a simple local goto. */
2467 simple_goto_p (tree expr
)
2469 return (TREE_CODE (expr
) == GOTO_EXPR
2470 && TREE_CODE (GOTO_DESTINATION (expr
)) == LABEL_DECL
);
2474 /* Return true if T should start a new basic block. PREV_T is the
2475 statement preceding T. It is used when T is a label or a case label.
2476 Labels should only start a new basic block if their previous statement
2477 wasn't a label. Otherwise, sequence of labels would generate
2478 unnecessary basic blocks that only contain a single label. */
2481 stmt_starts_bb_p (tree t
, tree prev_t
)
2483 enum tree_code code
;
2488 /* LABEL_EXPRs start a new basic block only if the preceding
2489 statement wasn't a label of the same type. This prevents the
2490 creation of consecutive blocks that have nothing but a single
2492 code
= TREE_CODE (t
);
2493 if (code
== LABEL_EXPR
)
2495 /* Nonlocal and computed GOTO targets always start a new block. */
2496 if (code
== LABEL_EXPR
2497 && (DECL_NONLOCAL (LABEL_EXPR_LABEL (t
))
2498 || FORCED_LABEL (LABEL_EXPR_LABEL (t
))))
2501 if (prev_t
&& TREE_CODE (prev_t
) == code
)
2503 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (prev_t
)))
2506 cfg_stats
.num_merged_labels
++;
2517 /* Return true if T should end a basic block. */
2520 stmt_ends_bb_p (tree t
)
2522 return is_ctrl_stmt (t
) || is_ctrl_altering_stmt (t
);
2526 /* Add gotos that used to be represented implicitly in the CFG. */
2529 disband_implicit_edges (void)
2532 block_stmt_iterator last
;
2538 last
= bsi_last (bb
);
2539 stmt
= last_stmt (bb
);
2541 if (stmt
&& TREE_CODE (stmt
) == COND_EXPR
)
2543 /* Remove superfluous gotos from COND_EXPR branches. Moved
2544 from cfg_remove_useless_stmts here since it violates the
2545 invariants for tree--cfg correspondence and thus fits better
2546 here where we do it anyway. */
2547 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
2549 if (e
->dest
!= bb
->next_bb
)
2552 if (e
->flags
& EDGE_TRUE_VALUE
)
2553 COND_EXPR_THEN (stmt
) = build_empty_stmt ();
2554 else if (e
->flags
& EDGE_FALSE_VALUE
)
2555 COND_EXPR_ELSE (stmt
) = build_empty_stmt ();
2558 e
->flags
|= EDGE_FALLTHRU
;
2564 if (stmt
&& TREE_CODE (stmt
) == RETURN_EXPR
)
2566 /* Remove the RETURN_EXPR if we may fall though to the exit
2569 || bb
->succ
->succ_next
2570 || bb
->succ
->dest
!= EXIT_BLOCK_PTR
)
2573 if (bb
->next_bb
== EXIT_BLOCK_PTR
2574 && !TREE_OPERAND (stmt
, 0))
2577 bb
->succ
->flags
|= EDGE_FALLTHRU
;
2582 /* There can be no fallthru edge if the last statement is a control
2584 if (stmt
&& is_ctrl_stmt (stmt
))
2587 /* Find a fallthru edge and emit the goto if necessary. */
2588 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
2589 if (e
->flags
& EDGE_FALLTHRU
)
2592 if (!e
|| e
->dest
== bb
->next_bb
)
2595 if (e
->dest
== EXIT_BLOCK_PTR
)
2598 label
= tree_block_label (e
->dest
);
2600 stmt
= build1 (GOTO_EXPR
, void_type_node
, label
);
2601 #ifdef USE_MAPPED_LOCATION
2602 SET_EXPR_LOCATION (stmt
, e
->goto_locus
);
2604 SET_EXPR_LOCUS (stmt
, e
->goto_locus
);
2606 bsi_insert_after (&last
, stmt
, BSI_NEW_STMT
);
2607 e
->flags
&= ~EDGE_FALLTHRU
;
2611 /* Remove block annotations and other datastructures. */
2614 delete_tree_cfg_annotations (void)
2617 if (n_basic_blocks
> 0)
2618 free_blocks_annotations ();
2620 label_to_block_map
= NULL
;
2627 /* Return the first statement in basic block BB. */
2630 first_stmt (basic_block bb
)
2632 block_stmt_iterator i
= bsi_start (bb
);
2633 return !bsi_end_p (i
) ? bsi_stmt (i
) : NULL_TREE
;
2637 /* Return the last statement in basic block BB. */
2640 last_stmt (basic_block bb
)
2642 block_stmt_iterator b
= bsi_last (bb
);
2643 return !bsi_end_p (b
) ? bsi_stmt (b
) : NULL_TREE
;
2647 /* Return a pointer to the last statement in block BB. */
2650 last_stmt_ptr (basic_block bb
)
2652 block_stmt_iterator last
= bsi_last (bb
);
2653 return !bsi_end_p (last
) ? bsi_stmt_ptr (last
) : NULL
;
2657 /* Return the last statement of an otherwise empty block. Return NULL
2658 if the block is totally empty, or if it contains more than one
2662 last_and_only_stmt (basic_block bb
)
2664 block_stmt_iterator i
= bsi_last (bb
);
2670 last
= bsi_stmt (i
);
2675 /* Empty statements should no longer appear in the instruction stream.
2676 Everything that might have appeared before should be deleted by
2677 remove_useless_stmts, and the optimizers should just bsi_remove
2678 instead of smashing with build_empty_stmt.
2680 Thus the only thing that should appear here in a block containing
2681 one executable statement is a label. */
2682 prev
= bsi_stmt (i
);
2683 if (TREE_CODE (prev
) == LABEL_EXPR
)
2690 /* Mark BB as the basic block holding statement T. */
2693 set_bb_for_stmt (tree t
, basic_block bb
)
2695 if (TREE_CODE (t
) == STATEMENT_LIST
)
2697 tree_stmt_iterator i
;
2698 for (i
= tsi_start (t
); !tsi_end_p (i
); tsi_next (&i
))
2699 set_bb_for_stmt (tsi_stmt (i
), bb
);
2703 stmt_ann_t ann
= get_stmt_ann (t
);
2706 /* If the statement is a label, add the label to block-to-labels map
2707 so that we can speed up edge creation for GOTO_EXPRs. */
2708 if (TREE_CODE (t
) == LABEL_EXPR
)
2712 t
= LABEL_EXPR_LABEL (t
);
2713 uid
= LABEL_DECL_UID (t
);
2716 LABEL_DECL_UID (t
) = uid
= cfun
->last_label_uid
++;
2717 if (VARRAY_SIZE (label_to_block_map
) <= (unsigned) uid
)
2718 VARRAY_GROW (label_to_block_map
, 3 * uid
/ 2);
2722 #ifdef ENABLE_CHECKING
2723 /* We're moving an existing label. Make sure that we've
2724 removed it from the old block. */
2725 if (bb
&& VARRAY_BB (label_to_block_map
, uid
))
2729 VARRAY_BB (label_to_block_map
, uid
) = bb
;
2735 /* Insert statement (or statement list) T before the statement
2736 pointed-to by iterator I. M specifies how to update iterator I
2737 after insertion (see enum bsi_iterator_update). */
2740 bsi_insert_before (block_stmt_iterator
*i
, tree t
, enum bsi_iterator_update m
)
2742 set_bb_for_stmt (t
, i
->bb
);
2743 tsi_link_before (&i
->tsi
, t
, m
);
2748 /* Insert statement (or statement list) T after the statement
2749 pointed-to by iterator I. M specifies how to update iterator I
2750 after insertion (see enum bsi_iterator_update). */
2753 bsi_insert_after (block_stmt_iterator
*i
, tree t
, enum bsi_iterator_update m
)
2755 set_bb_for_stmt (t
, i
->bb
);
2756 tsi_link_after (&i
->tsi
, t
, m
);
2761 /* Remove the statement pointed to by iterator I. The iterator is updated
2762 to the next statement. */
2765 bsi_remove (block_stmt_iterator
*i
)
2767 tree t
= bsi_stmt (*i
);
2768 set_bb_for_stmt (t
, NULL
);
2769 tsi_delink (&i
->tsi
);
2773 /* Move the statement at FROM so it comes right after the statement at TO. */
2776 bsi_move_after (block_stmt_iterator
*from
, block_stmt_iterator
*to
)
2778 tree stmt
= bsi_stmt (*from
);
2780 bsi_insert_after (to
, stmt
, BSI_SAME_STMT
);
2784 /* Move the statement at FROM so it comes right before the statement at TO. */
2787 bsi_move_before (block_stmt_iterator
*from
, block_stmt_iterator
*to
)
2789 tree stmt
= bsi_stmt (*from
);
2791 bsi_insert_before (to
, stmt
, BSI_SAME_STMT
);
2795 /* Move the statement at FROM to the end of basic block BB. */
2798 bsi_move_to_bb_end (block_stmt_iterator
*from
, basic_block bb
)
2800 block_stmt_iterator last
= bsi_last (bb
);
2802 /* Have to check bsi_end_p because it could be an empty block. */
2803 if (!bsi_end_p (last
) && is_ctrl_stmt (bsi_stmt (last
)))
2804 bsi_move_before (from
, &last
);
2806 bsi_move_after (from
, &last
);
2810 /* Replace the contents of the statement pointed to by iterator BSI
2811 with STMT. If PRESERVE_EH_INFO is true, the exception handling
2812 information of the original statement is preserved. */
2815 bsi_replace (const block_stmt_iterator
*bsi
, tree stmt
, bool preserve_eh_info
)
2818 tree orig_stmt
= bsi_stmt (*bsi
);
2820 SET_EXPR_LOCUS (stmt
, EXPR_LOCUS (orig_stmt
));
2821 set_bb_for_stmt (stmt
, bsi
->bb
);
2823 /* Preserve EH region information from the original statement, if
2824 requested by the caller. */
2825 if (preserve_eh_info
)
2827 eh_region
= lookup_stmt_eh_region (orig_stmt
);
2829 add_stmt_to_eh_region (stmt
, eh_region
);
2832 *bsi_stmt_ptr (*bsi
) = stmt
;
2837 /* Insert the statement pointed-to by BSI into edge E. Every attempt
2838 is made to place the statement in an existing basic block, but
2839 sometimes that isn't possible. When it isn't possible, the edge is
2840 split and the statement is added to the new block.
2842 In all cases, the returned *BSI points to the correct location. The
2843 return value is true if insertion should be done after the location,
2844 or false if it should be done before the location. If new basic block
2845 has to be created, it is stored in *NEW_BB. */
2848 tree_find_edge_insert_loc (edge e
, block_stmt_iterator
*bsi
,
2849 basic_block
*new_bb
)
2851 basic_block dest
, src
;
2857 /* If the destination has one predecessor which has no PHI nodes,
2858 insert there. Except for the exit block.
2860 The requirement for no PHI nodes could be relaxed. Basically we
2861 would have to examine the PHIs to prove that none of them used
2862 the value set by the statement we want to insert on E. That
2863 hardly seems worth the effort. */
2864 if (dest
->pred
->pred_next
== NULL
2865 && ! phi_nodes (dest
)
2866 && dest
!= EXIT_BLOCK_PTR
)
2868 *bsi
= bsi_start (dest
);
2869 if (bsi_end_p (*bsi
))
2872 /* Make sure we insert after any leading labels. */
2873 tmp
= bsi_stmt (*bsi
);
2874 while (TREE_CODE (tmp
) == LABEL_EXPR
)
2877 if (bsi_end_p (*bsi
))
2879 tmp
= bsi_stmt (*bsi
);
2882 if (bsi_end_p (*bsi
))
2884 *bsi
= bsi_last (dest
);
2891 /* If the source has one successor, the edge is not abnormal and
2892 the last statement does not end a basic block, insert there.
2893 Except for the entry block. */
2895 if ((e
->flags
& EDGE_ABNORMAL
) == 0
2896 && src
->succ
->succ_next
== NULL
2897 && src
!= ENTRY_BLOCK_PTR
)
2899 *bsi
= bsi_last (src
);
2900 if (bsi_end_p (*bsi
))
2903 tmp
= bsi_stmt (*bsi
);
2904 if (!stmt_ends_bb_p (tmp
))
2907 /* Insert code just before returning the value. We may need to decompose
2908 the return in the case it contains non-trivial operand. */
2909 if (TREE_CODE (tmp
) == RETURN_EXPR
)
2911 tree op
= TREE_OPERAND (tmp
, 0);
2912 if (!is_gimple_val (op
))
2914 if (TREE_CODE (op
) != MODIFY_EXPR
)
2916 bsi_insert_before (bsi
, op
, BSI_NEW_STMT
);
2917 TREE_OPERAND (tmp
, 0) = TREE_OPERAND (op
, 0);
2924 /* Otherwise, create a new basic block, and split this edge. */
2925 dest
= split_edge (e
);
2933 /* This routine will commit all pending edge insertions, creating any new
2934 basic blocks which are necessary.
2936 If specified, NEW_BLOCKS returns a count of the number of new basic
2937 blocks which were created. */
2940 bsi_commit_edge_inserts (int *new_blocks
)
2946 blocks
= n_basic_blocks
;
2948 bsi_commit_edge_inserts_1 (ENTRY_BLOCK_PTR
->succ
);
2951 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
2952 bsi_commit_edge_inserts_1 (e
);
2955 *new_blocks
= n_basic_blocks
- blocks
;
2959 /* Commit insertions pending at edge E. */
2962 bsi_commit_edge_inserts_1 (edge e
)
2964 if (PENDING_STMT (e
))
2966 block_stmt_iterator bsi
;
2967 tree stmt
= PENDING_STMT (e
);
2969 PENDING_STMT (e
) = NULL_TREE
;
2971 if (tree_find_edge_insert_loc (e
, &bsi
, NULL
))
2972 bsi_insert_after (&bsi
, stmt
, BSI_NEW_STMT
);
2974 bsi_insert_before (&bsi
, stmt
, BSI_NEW_STMT
);
2979 /* Add STMT to the pending list of edge E. No actual insertion is
2980 made until a call to bsi_commit_edge_inserts () is made. */
2983 bsi_insert_on_edge (edge e
, tree stmt
)
2985 append_to_statement_list (stmt
, &PENDING_STMT (e
));
2988 /* Similar to bsi_insert_on_edge+bsi_commit_edge_inserts. If new block has to
2989 be created, it is returned. */
2992 bsi_insert_on_edge_immediate (edge e
, tree stmt
)
2994 block_stmt_iterator bsi
;
2995 basic_block new_bb
= NULL
;
2997 if (PENDING_STMT (e
))
3000 if (tree_find_edge_insert_loc (e
, &bsi
, &new_bb
))
3001 bsi_insert_after (&bsi
, stmt
, BSI_NEW_STMT
);
3003 bsi_insert_before (&bsi
, stmt
, BSI_NEW_STMT
);
3008 /*---------------------------------------------------------------------------
3009 Tree specific functions for CFG manipulation
3010 ---------------------------------------------------------------------------*/
3012 /* Split a (typically critical) edge EDGE_IN. Return the new block.
3013 Abort on abnormal edges. */
3016 tree_split_edge (edge edge_in
)
3018 basic_block new_bb
, after_bb
, dest
, src
;
3023 /* Abnormal edges cannot be split. */
3024 if (edge_in
->flags
& EDGE_ABNORMAL
)
3028 dest
= edge_in
->dest
;
3030 /* Place the new block in the block list. Try to keep the new block
3031 near its "logical" location. This is of most help to humans looking
3032 at debugging dumps. */
3033 for (e
= dest
->pred
; e
; e
= e
->pred_next
)
3034 if (e
->src
->next_bb
== dest
)
3037 after_bb
= dest
->prev_bb
;
3039 after_bb
= edge_in
->src
;
3041 new_bb
= create_empty_bb (after_bb
);
3042 new_edge
= make_edge (new_bb
, dest
, EDGE_FALLTHRU
);
3044 /* Find all the PHI arguments on the original edge, and change them to
3045 the new edge. Do it before redirection, so that the argument does not
3047 for (phi
= phi_nodes (dest
); phi
; phi
= PHI_CHAIN (phi
))
3049 num_elem
= PHI_NUM_ARGS (phi
);
3050 for (i
= 0; i
< num_elem
; i
++)
3051 if (PHI_ARG_EDGE (phi
, i
) == edge_in
)
3053 PHI_ARG_EDGE (phi
, i
) = new_edge
;
3058 if (!redirect_edge_and_branch (edge_in
, new_bb
))
3061 if (PENDING_STMT (edge_in
))
3068 /* Return true when BB has label LABEL in it. */
3071 has_label_p (basic_block bb
, tree label
)
3073 block_stmt_iterator bsi
;
3075 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
3077 tree stmt
= bsi_stmt (bsi
);
3079 if (TREE_CODE (stmt
) != LABEL_EXPR
)
3081 if (LABEL_EXPR_LABEL (stmt
) == label
)
3088 /* Callback for walk_tree, check that all elements with address taken are
3089 properly noticed as such. */
3092 verify_expr (tree
*tp
, int *walk_subtrees
, void *data ATTRIBUTE_UNUSED
)
3099 /* Check operand N for being valid GIMPLE and give error MSG if not.
3100 We check for constants explicitly since they are not considered
3101 gimple invariants if they overflowed. */
3102 #define CHECK_OP(N, MSG) \
3103 do { if (TREE_CODE_CLASS (TREE_CODE (TREE_OPERAND (t, N))) != 'c' \
3104 && !is_gimple_val (TREE_OPERAND (t, N))) \
3105 { error (MSG); return TREE_OPERAND (t, N); }} while (0)
3107 switch (TREE_CODE (t
))
3110 if (SSA_NAME_IN_FREE_LIST (t
))
3112 error ("SSA name in freelist but still referenced");
3118 x
= TREE_OPERAND (t
, 0);
3119 if (TREE_CODE (x
) == BIT_FIELD_REF
3120 && is_gimple_reg (TREE_OPERAND (x
, 0)))
3122 error ("GIMPLE register modified with BIT_FIELD_REF");
3128 /* Skip any references (they will be checked when we recurse down the
3129 tree) and ensure that any variable used as a prefix is marked
3131 for (x
= TREE_OPERAND (t
, 0);
3132 (handled_component_p (x
)
3133 || TREE_CODE (x
) == REALPART_EXPR
3134 || TREE_CODE (x
) == IMAGPART_EXPR
);
3135 x
= TREE_OPERAND (x
, 0))
3138 if (TREE_CODE (x
) != VAR_DECL
&& TREE_CODE (x
) != PARM_DECL
)
3140 if (!TREE_ADDRESSABLE (x
))
3142 error ("address taken, but ADDRESSABLE bit not set");
3148 x
= TREE_OPERAND (t
, 0);
3149 if (TREE_CODE (TREE_TYPE (x
)) != BOOLEAN_TYPE
)
3151 error ("non-boolean used in condition");
3158 case FIX_TRUNC_EXPR
:
3160 case FIX_FLOOR_EXPR
:
3161 case FIX_ROUND_EXPR
:
3166 case NON_LVALUE_EXPR
:
3167 case TRUTH_NOT_EXPR
:
3168 CHECK_OP (0, "Invalid operand to unary operator");
3175 case ARRAY_RANGE_REF
:
3177 case VIEW_CONVERT_EXPR
:
3178 /* We have a nest of references. Verify that each of the operands
3179 that determine where to reference is either a constant or a variable,
3180 verify that the base is valid, and then show we've already checked
3182 while (TREE_CODE (t
) == REALPART_EXPR
|| TREE_CODE (t
) == IMAGPART_EXPR
3183 || handled_component_p (t
))
3185 if (TREE_CODE (t
) == COMPONENT_REF
&& TREE_OPERAND (t
, 2))
3186 CHECK_OP (2, "Invalid COMPONENT_REF offset operator");
3187 else if (TREE_CODE (t
) == ARRAY_REF
3188 || TREE_CODE (t
) == ARRAY_RANGE_REF
)
3190 CHECK_OP (1, "Invalid array index.");
3191 if (TREE_OPERAND (t
, 2))
3192 CHECK_OP (2, "Invalid array lower bound.");
3193 if (TREE_OPERAND (t
, 3))
3194 CHECK_OP (3, "Invalid array stride.");
3196 else if (TREE_CODE (t
) == BIT_FIELD_REF
)
3198 CHECK_OP (1, "Invalid operand to BIT_FIELD_REF");
3199 CHECK_OP (2, "Invalid operand to BIT_FIELD_REF");
3202 t
= TREE_OPERAND (t
, 0);
3205 if (TREE_CODE_CLASS (TREE_CODE (t
)) != 'c'
3206 && !is_gimple_lvalue (t
))
3208 error ("Invalid reference prefix.");
3220 case UNORDERED_EXPR
:
3231 case TRUNC_DIV_EXPR
:
3233 case FLOOR_DIV_EXPR
:
3234 case ROUND_DIV_EXPR
:
3235 case TRUNC_MOD_EXPR
:
3237 case FLOOR_MOD_EXPR
:
3238 case ROUND_MOD_EXPR
:
3240 case EXACT_DIV_EXPR
:
3250 CHECK_OP (0, "Invalid operand to binary operator");
3251 CHECK_OP (1, "Invalid operand to binary operator");
3263 /* Verify STMT, return true if STMT is not in GIMPLE form.
3264 TODO: Implement type checking. */
3267 verify_stmt (tree stmt
, bool last_in_block
)
3271 if (!is_gimple_stmt (stmt
))
3273 error ("Is not a valid GIMPLE statement.");
3277 addr
= walk_tree (&stmt
, verify_expr
, NULL
, NULL
);
3280 debug_generic_stmt (addr
);
3284 /* If the statement is marked as part of an EH region, then it is
3285 expected that the statement could throw. Verify that when we
3286 have optimizations that simplify statements such that we prove
3287 that they cannot throw, that we update other data structures
3289 if (lookup_stmt_eh_region (stmt
) >= 0)
3291 if (!tree_could_throw_p (stmt
))
3293 error ("Statement marked for throw, but doesn't.");
3296 if (!last_in_block
&& tree_can_throw_internal (stmt
))
3298 error ("Statement marked for throw in middle of block.");
3306 debug_generic_stmt (stmt
);
3311 /* Return true when the T can be shared. */
3314 tree_node_can_be_shared (tree t
)
3316 if (TYPE_P (t
) || DECL_P (t
)
3317 /* We check for constants explicitly since they are not considered
3318 gimple invariants if they overflowed. */
3319 || TREE_CODE_CLASS (TREE_CODE (t
)) == 'c'
3320 || is_gimple_min_invariant (t
)
3321 || TREE_CODE (t
) == SSA_NAME
)
3324 while (((TREE_CODE (t
) == ARRAY_REF
|| TREE_CODE (t
) == ARRAY_RANGE_REF
)
3325 /* We check for constants explicitly since they are not considered
3326 gimple invariants if they overflowed. */
3327 && (TREE_CODE_CLASS (TREE_CODE (TREE_OPERAND (t
, 1))) == 'c'
3328 || is_gimple_min_invariant (TREE_OPERAND (t
, 1))))
3329 || (TREE_CODE (t
) == COMPONENT_REF
3330 || TREE_CODE (t
) == REALPART_EXPR
3331 || TREE_CODE (t
) == IMAGPART_EXPR
))
3332 t
= TREE_OPERAND (t
, 0);
3341 /* Called via walk_trees. Verify tree sharing. */
3344 verify_node_sharing (tree
* tp
, int *walk_subtrees
, void *data
)
3346 htab_t htab
= (htab_t
) data
;
3349 if (tree_node_can_be_shared (*tp
))
3351 *walk_subtrees
= false;
3355 slot
= htab_find_slot (htab
, *tp
, INSERT
);
3364 /* Verify the GIMPLE statement chain. */
3370 block_stmt_iterator bsi
;
3375 timevar_push (TV_TREE_STMT_VERIFY
);
3376 htab
= htab_create (37, htab_hash_pointer
, htab_eq_pointer
, NULL
);
3383 for (phi
= phi_nodes (bb
); phi
; phi
= PHI_CHAIN (phi
))
3385 int phi_num_args
= PHI_NUM_ARGS (phi
);
3387 for (i
= 0; i
< phi_num_args
; i
++)
3389 tree t
= PHI_ARG_DEF (phi
, i
);
3392 /* Addressable variables do have SSA_NAMEs but they
3393 are not considered gimple values. */
3394 if (TREE_CODE (t
) != SSA_NAME
3395 && TREE_CODE (t
) != FUNCTION_DECL
3396 && !is_gimple_val (t
))
3398 error ("PHI def is not a GIMPLE value");
3399 debug_generic_stmt (phi
);
3400 debug_generic_stmt (t
);
3404 addr
= walk_tree (&t
, verify_expr
, NULL
, NULL
);
3407 debug_generic_stmt (addr
);
3411 addr
= walk_tree (&t
, verify_node_sharing
, htab
, NULL
);
3414 error ("Incorrect sharing of tree nodes");
3415 debug_generic_stmt (phi
);
3416 debug_generic_stmt (addr
);
3422 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); )
3424 tree stmt
= bsi_stmt (bsi
);
3426 err
|= verify_stmt (stmt
, bsi_end_p (bsi
));
3427 addr
= walk_tree (&stmt
, verify_node_sharing
, htab
, NULL
);
3430 error ("Incorrect sharing of tree nodes");
3431 debug_generic_stmt (stmt
);
3432 debug_generic_stmt (addr
);
3439 internal_error ("verify_stmts failed.");
3442 timevar_pop (TV_TREE_STMT_VERIFY
);
3446 /* Verifies that the flow information is OK. */
3449 tree_verify_flow_info (void)
3453 block_stmt_iterator bsi
;
3457 if (ENTRY_BLOCK_PTR
->stmt_list
)
3459 error ("ENTRY_BLOCK has a statement list associated with it\n");
3463 if (EXIT_BLOCK_PTR
->stmt_list
)
3465 error ("EXIT_BLOCK has a statement list associated with it\n");
3469 for (e
= EXIT_BLOCK_PTR
->pred
; e
; e
= e
->pred_next
)
3470 if (e
->flags
& EDGE_FALLTHRU
)
3472 error ("Fallthru to exit from bb %d\n", e
->src
->index
);
3478 bool found_ctrl_stmt
= false;
3480 /* Skip labels on the start of basic block. */
3481 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
3483 if (TREE_CODE (bsi_stmt (bsi
)) != LABEL_EXPR
)
3486 if (label_to_block (LABEL_EXPR_LABEL (bsi_stmt (bsi
))) != bb
)
3488 error ("Label %s to block does not match in bb %d\n",
3489 IDENTIFIER_POINTER (DECL_NAME (bsi_stmt (bsi
))),
3494 if (decl_function_context (LABEL_EXPR_LABEL (bsi_stmt (bsi
)))
3495 != current_function_decl
)
3497 error ("Label %s has incorrect context in bb %d\n",
3498 IDENTIFIER_POINTER (DECL_NAME (bsi_stmt (bsi
))),
3504 /* Verify that body of basic block BB is free of control flow. */
3505 for (; !bsi_end_p (bsi
); bsi_next (&bsi
))
3507 tree stmt
= bsi_stmt (bsi
);
3509 if (found_ctrl_stmt
)
3511 error ("Control flow in the middle of basic block %d\n",
3516 if (stmt_ends_bb_p (stmt
))
3517 found_ctrl_stmt
= true;
3519 if (TREE_CODE (stmt
) == LABEL_EXPR
)
3521 error ("Label %s in the middle of basic block %d\n",
3522 IDENTIFIER_POINTER (DECL_NAME (stmt
)),
3527 bsi
= bsi_last (bb
);
3528 if (bsi_end_p (bsi
))
3531 stmt
= bsi_stmt (bsi
);
3533 if (is_ctrl_stmt (stmt
))
3535 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
3536 if (e
->flags
& EDGE_FALLTHRU
)
3538 error ("Fallthru edge after a control statement in bb %d \n",
3544 switch (TREE_CODE (stmt
))
3550 if (TREE_CODE (COND_EXPR_THEN (stmt
)) != GOTO_EXPR
3551 || TREE_CODE (COND_EXPR_ELSE (stmt
)) != GOTO_EXPR
)
3553 error ("Structured COND_EXPR at the end of bb %d\n", bb
->index
);
3557 extract_true_false_edges_from_block (bb
, &true_edge
, &false_edge
);
3559 if (!true_edge
|| !false_edge
3560 || !(true_edge
->flags
& EDGE_TRUE_VALUE
)
3561 || !(false_edge
->flags
& EDGE_FALSE_VALUE
)
3562 || (true_edge
->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
))
3563 || (false_edge
->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
))
3564 || bb
->succ
->succ_next
->succ_next
)
3566 error ("Wrong outgoing edge flags at end of bb %d\n",
3571 if (!has_label_p (true_edge
->dest
,
3572 GOTO_DESTINATION (COND_EXPR_THEN (stmt
))))
3574 error ("`then' label does not match edge at end of bb %d\n",
3579 if (!has_label_p (false_edge
->dest
,
3580 GOTO_DESTINATION (COND_EXPR_ELSE (stmt
))))
3582 error ("`else' label does not match edge at end of bb %d\n",
3590 if (simple_goto_p (stmt
))
3592 error ("Explicit goto at end of bb %d\n", bb
->index
);
3597 /* FIXME. We should double check that the labels in the
3598 destination blocks have their address taken. */
3599 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
3600 if ((e
->flags
& (EDGE_FALLTHRU
| EDGE_TRUE_VALUE
3601 | EDGE_FALSE_VALUE
))
3602 || !(e
->flags
& EDGE_ABNORMAL
))
3604 error ("Wrong outgoing edge flags at end of bb %d\n",
3612 if (!bb
->succ
|| bb
->succ
->succ_next
3613 || (bb
->succ
->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
3614 | EDGE_TRUE_VALUE
| EDGE_FALSE_VALUE
)))
3616 error ("Wrong outgoing edge flags at end of bb %d\n", bb
->index
);
3619 if (bb
->succ
->dest
!= EXIT_BLOCK_PTR
)
3621 error ("Return edge does not point to exit in bb %d\n",
3634 vec
= SWITCH_LABELS (stmt
);
3635 n
= TREE_VEC_LENGTH (vec
);
3637 /* Mark all the destination basic blocks. */
3638 for (i
= 0; i
< n
; ++i
)
3640 tree lab
= CASE_LABEL (TREE_VEC_ELT (vec
, i
));
3641 basic_block label_bb
= label_to_block (lab
);
3643 if (label_bb
->aux
&& label_bb
->aux
!= (void *)1)
3645 label_bb
->aux
= (void *)1;
3648 /* Verify that the case labels are sorted. */
3649 prev
= TREE_VEC_ELT (vec
, 0);
3650 for (i
= 1; i
< n
- 1; ++i
)
3652 tree c
= TREE_VEC_ELT (vec
, i
);
3655 error ("Found default case not at end of case vector");
3659 if (! tree_int_cst_lt (CASE_LOW (prev
), CASE_LOW (c
)))
3661 error ("Case labels not sorted:\n ");
3662 print_generic_expr (stderr
, prev
, 0);
3663 fprintf (stderr
," is greater than ");
3664 print_generic_expr (stderr
, c
, 0);
3665 fprintf (stderr
," but comes before it.\n");
3670 if (CASE_LOW (TREE_VEC_ELT (vec
, n
- 1)))
3672 error ("No default case found at end of case vector");
3676 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
3680 error ("Extra outgoing edge %d->%d\n",
3681 bb
->index
, e
->dest
->index
);
3684 e
->dest
->aux
= (void *)2;
3685 if ((e
->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
3686 | EDGE_TRUE_VALUE
| EDGE_FALSE_VALUE
)))
3688 error ("Wrong outgoing edge flags at end of bb %d\n",
3694 /* Check that we have all of them. */
3695 for (i
= 0; i
< n
; ++i
)
3697 tree lab
= CASE_LABEL (TREE_VEC_ELT (vec
, i
));
3698 basic_block label_bb
= label_to_block (lab
);
3700 if (label_bb
->aux
!= (void *)2)
3702 error ("Missing edge %i->%i\n",
3703 bb
->index
, label_bb
->index
);
3708 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
3709 e
->dest
->aux
= (void *)0;
3716 if (dom_computed
[CDI_DOMINATORS
] >= DOM_NO_FAST_QUERY
)
3717 verify_dominators (CDI_DOMINATORS
);
3723 /* Updates phi nodes after creating forwarder block joined
3724 by edge FALLTHRU. */
3727 tree_make_forwarder_block (edge fallthru
)
3730 basic_block dummy
, bb
;
3731 tree phi
, new_phi
, var
, prev
, next
;
3733 dummy
= fallthru
->src
;
3734 bb
= fallthru
->dest
;
3736 if (!bb
->pred
->pred_next
)
3739 /* If we redirected a branch we must create new phi nodes at the
3741 for (phi
= phi_nodes (dummy
); phi
; phi
= PHI_CHAIN (phi
))
3743 var
= PHI_RESULT (phi
);
3744 new_phi
= create_phi_node (var
, bb
);
3745 SSA_NAME_DEF_STMT (var
) = new_phi
;
3746 SET_PHI_RESULT (phi
, make_ssa_name (SSA_NAME_VAR (var
), phi
));
3747 add_phi_arg (&new_phi
, PHI_RESULT (phi
), fallthru
);
3750 /* Ensure that the PHI node chain is in the same order. */
3752 for (phi
= phi_nodes (bb
); phi
; phi
= next
)
3754 next
= PHI_CHAIN (phi
);
3755 PHI_CHAIN (phi
) = prev
;
3758 set_phi_nodes (bb
, prev
);
3760 /* Add the arguments we have stored on edges. */
3761 for (e
= bb
->pred
; e
; e
= e
->pred_next
)
3766 for (phi
= phi_nodes (bb
), var
= PENDING_STMT (e
);
3768 phi
= PHI_CHAIN (phi
), var
= TREE_CHAIN (var
))
3769 add_phi_arg (&phi
, TREE_VALUE (var
), e
);
3771 PENDING_STMT (e
) = NULL
;
3776 /* Return true if basic block BB does nothing except pass control
3777 flow to another block and that we can safely insert a label at
3778 the start of the successor block. */
3781 tree_forwarder_block_p (basic_block bb
)
3783 block_stmt_iterator bsi
;
3786 /* If we have already determined that this block is not forwardable,
3787 then no further checks are necessary. */
3788 if (! bb_ann (bb
)->forwardable
)
3791 /* BB must have a single outgoing normal edge. Otherwise it can not be
3792 a forwarder block. */
3794 || bb
->succ
->succ_next
3795 || bb
->succ
->dest
== EXIT_BLOCK_PTR
3796 || (bb
->succ
->flags
& EDGE_ABNORMAL
)
3797 || bb
== ENTRY_BLOCK_PTR
)
3799 bb_ann (bb
)->forwardable
= 0;
3803 /* Successors of the entry block are not forwarders. */
3804 for (e
= ENTRY_BLOCK_PTR
->succ
; e
; e
= e
->succ_next
)
3807 bb_ann (bb
)->forwardable
= 0;
3811 /* BB can not have any PHI nodes. This could potentially be relaxed
3812 early in compilation if we re-rewrote the variables appearing in
3813 any PHI nodes in forwarder blocks. */
3816 bb_ann (bb
)->forwardable
= 0;
3820 /* Now walk through the statements. We can ignore labels, anything else
3821 means this is not a forwarder block. */
3822 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
3824 tree stmt
= bsi_stmt (bsi
);
3826 switch (TREE_CODE (stmt
))
3829 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt
)))
3834 bb_ann (bb
)->forwardable
= 0;
3843 /* Thread jumps over empty statements.
3845 This code should _not_ thread over obviously equivalent conditions
3846 as that requires nontrivial updates to the SSA graph. */
3851 edge e
, next
, last
, old
;
3852 basic_block bb
, dest
, tmp
, old_dest
, dom
;
3855 bool retval
= false;
3858 bb_ann (bb
)->forwardable
= 1;
3860 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
, EXIT_BLOCK_PTR
, next_bb
)
3862 /* Don't waste time on unreachable blocks. */
3866 /* Nor on forwarders. */
3867 if (tree_forwarder_block_p (bb
))
3870 /* This block is now part of a forwarding path, mark it as not
3871 forwardable so that we can detect loops. This bit will be
3873 bb_ann (bb
)->forwardable
= 0;
3875 /* Examine each of our block's successors to see if it is
3877 for (e
= bb
->succ
; e
; e
= next
)
3879 next
= e
->succ_next
;
3881 /* If the edge is abnormal or its destination is not
3882 forwardable, then there's nothing to do. */
3883 if ((e
->flags
& EDGE_ABNORMAL
)
3884 || !tree_forwarder_block_p (e
->dest
))
3887 /* Now walk through as many forwarder block as possible to
3888 find the ultimate destination we want to thread our jump
3890 last
= e
->dest
->succ
;
3891 bb_ann (e
->dest
)->forwardable
= 0;
3892 for (dest
= e
->dest
->succ
->dest
;
3893 tree_forwarder_block_p (dest
);
3895 dest
= dest
->succ
->dest
)
3897 /* An infinite loop detected. We redirect the edge anyway, so
3898 that the loop is shrunk into single basic block. */
3899 if (!bb_ann (dest
)->forwardable
)
3902 if (dest
->succ
->dest
== EXIT_BLOCK_PTR
)
3905 bb_ann (dest
)->forwardable
= 0;
3908 /* Reset the forwardable marks to 1. */
3911 tmp
= tmp
->succ
->dest
)
3912 bb_ann (tmp
)->forwardable
= 1;
3914 if (dest
== e
->dest
)
3917 old
= find_edge (bb
, dest
);
3920 /* If there already is an edge, check whether the values
3921 in phi nodes differ. */
3922 if (!phi_alternatives_equal (dest
, last
, old
))
3924 /* The previous block is forwarder. Redirect our jump
3925 to that target instead since we know it has no PHI
3926 nodes that will need updating. */
3929 /* That might mean that no forwarding at all is possible. */
3930 if (dest
== e
->dest
)
3933 old
= find_edge (bb
, dest
);
3937 /* Perform the redirection. */
3940 e
= redirect_edge_and_branch (e
, dest
);
3944 /* Update PHI nodes. We know that the new argument should
3945 have the same value as the argument associated with LAST.
3946 Otherwise we would have changed our target block above. */
3947 for (phi
= phi_nodes (dest
); phi
; phi
= PHI_CHAIN (phi
))
3949 arg
= phi_arg_from_edge (phi
, last
);
3952 add_phi_arg (&phi
, PHI_ARG_DEF (phi
, arg
), e
);
3956 /* Update the dominators. */
3957 if (dom_computed
[CDI_DOMINATORS
] >= DOM_CONS_OK
)
3959 /* Remove the unreachable blocks (observe that if all blocks
3960 were reachable before, only those in the path we threaded
3961 over and did not have any predecessor outside of the path
3962 become unreachable). */
3963 for (; old_dest
!= dest
; old_dest
= tmp
)
3965 tmp
= old_dest
->succ
->dest
;
3970 delete_basic_block (old_dest
);
3972 /* If the dominator of the destination was in the path, set its
3973 dominator to the start of the redirected edge. */
3974 if (get_immediate_dominator (CDI_DOMINATORS
, old_dest
) == NULL
)
3975 set_immediate_dominator (CDI_DOMINATORS
, old_dest
, bb
);
3977 /* Now proceed like if we forwarded just over one edge at a time.
3978 Algorithm for forwarding over edge A --> B then is
3981 idom (B) = idom (A);
3982 recount_idom (A); */
3984 for (; old_dest
!= dest
; old_dest
= tmp
)
3986 tmp
= old_dest
->succ
->dest
;
3988 if (get_immediate_dominator (CDI_DOMINATORS
, tmp
) == old_dest
)
3990 dom
= get_immediate_dominator (CDI_DOMINATORS
, old_dest
);
3991 set_immediate_dominator (CDI_DOMINATORS
, tmp
, dom
);
3994 dom
= recount_dominator (CDI_DOMINATORS
, old_dest
);
3995 set_immediate_dominator (CDI_DOMINATORS
, old_dest
, dom
);
4000 /* Reset the forwardable bit on our block since it's no longer in
4001 a forwarding chain path. */
4002 bb_ann (bb
)->forwardable
= 1;
4009 /* Return a non-special label in the head of basic block BLOCK.
4010 Create one if it doesn't exist. */
4013 tree_block_label (basic_block bb
)
4015 block_stmt_iterator i
, s
= bsi_start (bb
);
4019 for (i
= s
; !bsi_end_p (i
); first
= false, bsi_next (&i
))
4021 stmt
= bsi_stmt (i
);
4022 if (TREE_CODE (stmt
) != LABEL_EXPR
)
4024 label
= LABEL_EXPR_LABEL (stmt
);
4025 if (!DECL_NONLOCAL (label
))
4028 bsi_move_before (&i
, &s
);
4033 label
= create_artificial_label ();
4034 stmt
= build1 (LABEL_EXPR
, void_type_node
, label
);
4035 bsi_insert_before (&s
, stmt
, BSI_NEW_STMT
);
4040 /* Attempt to perform edge redirection by replacing a possibly complex
4041 jump instruction by a goto or by removing the jump completely.
4042 This can apply only if all edges now point to the same block. The
4043 parameters and return values are equivalent to
4044 redirect_edge_and_branch. */
4047 tree_try_redirect_by_replacing_jump (edge e
, basic_block target
)
4049 basic_block src
= e
->src
;
4051 block_stmt_iterator b
;
4054 /* Verify that all targets will be TARGET. */
4055 for (tmp
= src
->succ
; tmp
; tmp
= tmp
->succ_next
)
4056 if (tmp
->dest
!= target
&& tmp
!= e
)
4065 stmt
= bsi_stmt (b
);
4067 if (TREE_CODE (stmt
) == COND_EXPR
4068 || TREE_CODE (stmt
) == SWITCH_EXPR
)
4071 e
= ssa_redirect_edge (e
, target
);
4072 e
->flags
= EDGE_FALLTHRU
;
4080 /* Redirect E to DEST. Return NULL on failure. Otherwise, return the
4081 edge representing the redirected branch. */
4084 tree_redirect_edge_and_branch (edge e
, basic_block dest
)
4086 basic_block bb
= e
->src
;
4087 block_stmt_iterator bsi
;
4091 if (e
->flags
& (EDGE_ABNORMAL_CALL
| EDGE_EH
))
4094 if (e
->src
!= ENTRY_BLOCK_PTR
4095 && (ret
= tree_try_redirect_by_replacing_jump (e
, dest
)))
4098 if (e
->dest
== dest
)
4101 label
= tree_block_label (dest
);
4103 bsi
= bsi_last (bb
);
4104 stmt
= bsi_end_p (bsi
) ? NULL
: bsi_stmt (bsi
);
4106 switch (stmt
? TREE_CODE (stmt
) : ERROR_MARK
)
4109 stmt
= (e
->flags
& EDGE_TRUE_VALUE
4110 ? COND_EXPR_THEN (stmt
)
4111 : COND_EXPR_ELSE (stmt
));
4112 GOTO_DESTINATION (stmt
) = label
;
4116 /* No non-abnormal edges should lead from a non-simple goto, and
4117 simple ones should be represented implicitly. */
4122 tree vec
= SWITCH_LABELS (stmt
);
4123 size_t i
, n
= TREE_VEC_LENGTH (vec
);
4125 for (i
= 0; i
< n
; ++i
)
4127 tree elt
= TREE_VEC_ELT (vec
, i
);
4128 if (label_to_block (CASE_LABEL (elt
)) == e
->dest
)
4129 CASE_LABEL (elt
) = label
;
4136 e
->flags
|= EDGE_FALLTHRU
;
4140 /* Otherwise it must be a fallthru edge, and we don't need to
4141 do anything besides redirecting it. */
4142 if (!(e
->flags
& EDGE_FALLTHRU
))
4147 /* Update/insert PHI nodes as necessary. */
4149 /* Now update the edges in the CFG. */
4150 e
= ssa_redirect_edge (e
, dest
);
4156 /* Simple wrapper, as we can always redirect fallthru edges. */
4159 tree_redirect_edge_and_branch_force (edge e
, basic_block dest
)
4161 e
= tree_redirect_edge_and_branch (e
, dest
);
4169 /* Splits basic block BB after statement STMT (but at least after the
4170 labels). If STMT is NULL, BB is split just after the labels. */
4173 tree_split_block (basic_block bb
, void *stmt
)
4175 block_stmt_iterator bsi
, bsi_tgt
;
4180 new_bb
= create_empty_bb (bb
);
4182 /* Redirect the outgoing edges. */
4183 new_bb
->succ
= bb
->succ
;
4185 for (e
= new_bb
->succ
; e
; e
= e
->succ_next
)
4188 if (stmt
&& TREE_CODE ((tree
) stmt
) == LABEL_EXPR
)
4191 /* Move everything from BSI to the new basic block. */
4192 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
4194 act
= bsi_stmt (bsi
);
4195 if (TREE_CODE (act
) == LABEL_EXPR
)
4208 bsi_tgt
= bsi_start (new_bb
);
4209 while (!bsi_end_p (bsi
))
4211 act
= bsi_stmt (bsi
);
4213 bsi_insert_after (&bsi_tgt
, act
, BSI_NEW_STMT
);
4220 /* Moves basic block BB after block AFTER. */
4223 tree_move_block_after (basic_block bb
, basic_block after
)
4225 if (bb
->prev_bb
== after
)
4229 link_block (bb
, after
);
4235 /* Return true if basic_block can be duplicated. */
4238 tree_can_duplicate_bb_p (basic_block bb ATTRIBUTE_UNUSED
)
4244 /* Create a duplicate of the basic block BB. NOTE: This does not
4245 preserve SSA form. */
4248 tree_duplicate_bb (basic_block bb
)
4251 block_stmt_iterator bsi
, bsi_tgt
;
4253 ssa_op_iter op_iter
;
4255 new_bb
= create_empty_bb (EXIT_BLOCK_PTR
->prev_bb
);
4257 for (phi
= phi_nodes (bb
); phi
; phi
= TREE_CHAIN (phi
))
4259 mark_for_rewrite (PHI_RESULT (phi
));
4262 bsi_tgt
= bsi_start (new_bb
);
4263 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
4265 tree stmt
= bsi_stmt (bsi
);
4268 if (TREE_CODE (stmt
) == LABEL_EXPR
)
4271 /* Record the definitions. */
4272 get_stmt_operands (stmt
);
4274 FOR_EACH_SSA_TREE_OPERAND (val
, stmt
, op_iter
, SSA_OP_ALL_DEFS
)
4275 mark_for_rewrite (val
);
4277 copy
= unshare_expr (stmt
);
4279 /* Copy also the virtual operands. */
4280 get_stmt_ann (copy
);
4281 copy_virtual_operands (copy
, stmt
);
4283 bsi_insert_after (&bsi_tgt
, copy
, BSI_NEW_STMT
);
4290 /* Dump FUNCTION_DECL FN to file FILE using FLAGS (see TDF_* in tree.h) */
4293 dump_function_to_file (tree fn
, FILE *file
, int flags
)
4295 tree arg
, vars
, var
;
4296 bool ignore_topmost_bind
= false, any_var
= false;
4300 fprintf (file
, "%s (", lang_hooks
.decl_printable_name (fn
, 2));
4302 arg
= DECL_ARGUMENTS (fn
);
4305 print_generic_expr (file
, arg
, dump_flags
);
4306 if (TREE_CHAIN (arg
))
4307 fprintf (file
, ", ");
4308 arg
= TREE_CHAIN (arg
);
4310 fprintf (file
, ")\n");
4312 if (flags
& TDF_RAW
)
4314 dump_node (fn
, TDF_SLIM
| flags
, file
);
4318 /* When GIMPLE is lowered, the variables are no longer available in
4319 BIND_EXPRs, so display them separately. */
4320 if (cfun
&& cfun
->unexpanded_var_list
)
4322 ignore_topmost_bind
= true;
4324 fprintf (file
, "{\n");
4325 for (vars
= cfun
->unexpanded_var_list
; vars
; vars
= TREE_CHAIN (vars
))
4327 var
= TREE_VALUE (vars
);
4329 print_generic_decl (file
, var
, flags
);
4330 fprintf (file
, "\n");
4336 if (basic_block_info
)
4338 /* Make a CFG based dump. */
4339 check_bb_profile (ENTRY_BLOCK_PTR
, file
);
4340 if (!ignore_topmost_bind
)
4341 fprintf (file
, "{\n");
4343 if (any_var
&& n_basic_blocks
)
4344 fprintf (file
, "\n");
4347 dump_generic_bb (file
, bb
, 2, flags
);
4349 fprintf (file
, "}\n");
4350 check_bb_profile (EXIT_BLOCK_PTR
, file
);
4356 /* Make a tree based dump. */
4357 chain
= DECL_SAVED_TREE (fn
);
4359 if (TREE_CODE (chain
) == BIND_EXPR
)
4361 if (ignore_topmost_bind
)
4363 chain
= BIND_EXPR_BODY (chain
);
4371 if (!ignore_topmost_bind
)
4372 fprintf (file
, "{\n");
4377 fprintf (file
, "\n");
4379 print_generic_stmt_indented (file
, chain
, flags
, indent
);
4380 if (ignore_topmost_bind
)
4381 fprintf (file
, "}\n");
4384 fprintf (file
, "\n\n");
4388 /* Pretty print of the loops intermediate representation. */
4389 static void print_loop (FILE *, struct loop
*, int);
4390 static void print_pred_bbs (FILE *, edge
);
4391 static void print_succ_bbs (FILE *, edge
);
4394 /* Print the predecessors indexes of edge E on FILE. */
4397 print_pred_bbs (FILE *file
, edge e
)
4402 else if (e
->pred_next
== NULL
)
4403 fprintf (file
, "bb_%d", e
->src
->index
);
4407 fprintf (file
, "bb_%d, ", e
->src
->index
);
4408 print_pred_bbs (file
, e
->pred_next
);
4413 /* Print the successors indexes of edge E on FILE. */
4416 print_succ_bbs (FILE *file
, edge e
)
4420 else if (e
->succ_next
== NULL
)
4421 fprintf (file
, "bb_%d", e
->dest
->index
);
4424 fprintf (file
, "bb_%d, ", e
->dest
->index
);
4425 print_succ_bbs (file
, e
->succ_next
);
4430 /* Pretty print LOOP on FILE, indented INDENT spaces. */
4433 print_loop (FILE *file
, struct loop
*loop
, int indent
)
4441 s_indent
= (char *) alloca ((size_t) indent
+ 1);
4442 memset ((void *) s_indent
, ' ', (size_t) indent
);
4443 s_indent
[indent
] = '\0';
4445 /* Print the loop's header. */
4446 fprintf (file
, "%sloop_%d\n", s_indent
, loop
->num
);
4448 /* Print the loop's body. */
4449 fprintf (file
, "%s{\n", s_indent
);
4451 if (bb
->loop_father
== loop
)
4453 /* Print the basic_block's header. */
4454 fprintf (file
, "%s bb_%d (preds = {", s_indent
, bb
->index
);
4455 print_pred_bbs (file
, bb
->pred
);
4456 fprintf (file
, "}, succs = {");
4457 print_succ_bbs (file
, bb
->succ
);
4458 fprintf (file
, "})\n");
4460 /* Print the basic_block's body. */
4461 fprintf (file
, "%s {\n", s_indent
);
4462 tree_dump_bb (bb
, file
, indent
+ 4);
4463 fprintf (file
, "%s }\n", s_indent
);
4466 print_loop (file
, loop
->inner
, indent
+ 2);
4467 fprintf (file
, "%s}\n", s_indent
);
4468 print_loop (file
, loop
->next
, indent
);
4472 /* Follow a CFG edge from the entry point of the program, and on entry
4473 of a loop, pretty print the loop structure on FILE. */
4476 print_loop_ir (FILE *file
)
4480 bb
= BASIC_BLOCK (0);
4481 if (bb
&& bb
->loop_father
)
4482 print_loop (file
, bb
->loop_father
, 0);
4486 /* Debugging loops structure at tree level. */
4489 debug_loop_ir (void)
4491 print_loop_ir (stderr
);
4495 /* Return true if BB ends with a call, possibly followed by some
4496 instructions that must stay with the call. Return false,
4500 tree_block_ends_with_call_p (basic_block bb
)
4502 block_stmt_iterator bsi
= bsi_last (bb
);
4503 return get_call_expr_in (bsi_stmt (bsi
)) != NULL
;
4507 /* Return true if BB ends with a conditional branch. Return false,
4511 tree_block_ends_with_condjump_p (basic_block bb
)
4513 tree stmt
= tsi_stmt (bsi_last (bb
).tsi
);
4514 return (TREE_CODE (stmt
) == COND_EXPR
);
4518 /* Return true if we need to add fake edge to exit at statement T.
4519 Helper function for tree_flow_call_edges_add. */
4522 need_fake_edge_p (tree t
)
4526 /* NORETURN and LONGJMP calls already have an edge to exit.
4527 CONST, PURE and ALWAYS_RETURN calls do not need one.
4528 We don't currently check for CONST and PURE here, although
4529 it would be a good idea, because those attributes are
4530 figured out from the RTL in mark_constant_function, and
4531 the counter incrementation code from -fprofile-arcs
4532 leads to different results from -fbranch-probabilities. */
4533 call
= get_call_expr_in (t
);
4535 && !(call_expr_flags (call
) &
4536 (ECF_NORETURN
| ECF_LONGJMP
| ECF_ALWAYS_RETURN
)))
4539 if (TREE_CODE (t
) == ASM_EXPR
4540 && (ASM_VOLATILE_P (t
) || ASM_INPUT_P (t
)))
4547 /* Add fake edges to the function exit for any non constant and non
4548 noreturn calls, volatile inline assembly in the bitmap of blocks
4549 specified by BLOCKS or to the whole CFG if BLOCKS is zero. Return
4550 the number of blocks that were split.
4552 The goal is to expose cases in which entering a basic block does
4553 not imply that all subsequent instructions must be executed. */
4556 tree_flow_call_edges_add (sbitmap blocks
)
4559 int blocks_split
= 0;
4560 int last_bb
= last_basic_block
;
4561 bool check_last_block
= false;
4563 if (n_basic_blocks
== 0)
4567 check_last_block
= true;
4569 check_last_block
= TEST_BIT (blocks
, EXIT_BLOCK_PTR
->prev_bb
->index
);
4571 /* In the last basic block, before epilogue generation, there will be
4572 a fallthru edge to EXIT. Special care is required if the last insn
4573 of the last basic block is a call because make_edge folds duplicate
4574 edges, which would result in the fallthru edge also being marked
4575 fake, which would result in the fallthru edge being removed by
4576 remove_fake_edges, which would result in an invalid CFG.
4578 Moreover, we can't elide the outgoing fake edge, since the block
4579 profiler needs to take this into account in order to solve the minimal
4580 spanning tree in the case that the call doesn't return.
4582 Handle this by adding a dummy instruction in a new last basic block. */
4583 if (check_last_block
)
4585 basic_block bb
= EXIT_BLOCK_PTR
->prev_bb
;
4586 block_stmt_iterator bsi
= bsi_last (bb
);
4588 if (!bsi_end_p (bsi
))
4591 if (need_fake_edge_p (t
))
4595 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
4596 if (e
->dest
== EXIT_BLOCK_PTR
)
4598 bsi_insert_on_edge (e
, build_empty_stmt ());
4599 bsi_commit_edge_inserts ((int *)NULL
);
4605 /* Now add fake edges to the function exit for any non constant
4606 calls since there is no way that we can determine if they will
4608 for (i
= 0; i
< last_bb
; i
++)
4610 basic_block bb
= BASIC_BLOCK (i
);
4611 block_stmt_iterator bsi
;
4612 tree stmt
, last_stmt
;
4617 if (blocks
&& !TEST_BIT (blocks
, i
))
4620 bsi
= bsi_last (bb
);
4621 if (!bsi_end_p (bsi
))
4623 last_stmt
= bsi_stmt (bsi
);
4626 stmt
= bsi_stmt (bsi
);
4627 if (need_fake_edge_p (stmt
))
4630 /* The handling above of the final block before the
4631 epilogue should be enough to verify that there is
4632 no edge to the exit block in CFG already.
4633 Calling make_edge in such case would cause us to
4634 mark that edge as fake and remove it later. */
4635 #ifdef ENABLE_CHECKING
4636 if (stmt
== last_stmt
)
4637 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
4638 if (e
->dest
== EXIT_BLOCK_PTR
)
4642 /* Note that the following may create a new basic block
4643 and renumber the existing basic blocks. */
4644 if (stmt
!= last_stmt
)
4646 e
= split_block (bb
, stmt
);
4650 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
4654 while (!bsi_end_p (bsi
));
4659 verify_flow_info ();
4661 return blocks_split
;
4665 tree_purge_dead_eh_edges (basic_block bb
)
4667 bool changed
= false;
4669 tree stmt
= last_stmt (bb
);
4671 if (stmt
&& tree_can_throw_internal (stmt
))
4674 for (e
= bb
->succ
; e
; e
= next
)
4676 next
= e
->succ_next
;
4677 if (e
->flags
& EDGE_EH
)
4679 ssa_remove_edge (e
);
4688 tree_purge_all_dead_eh_edges (bitmap blocks
)
4690 bool changed
= false;
4693 EXECUTE_IF_SET_IN_BITMAP (blocks
, 0, i
,
4694 { changed
|= tree_purge_dead_eh_edges (BASIC_BLOCK (i
)); });
4699 struct cfg_hooks tree_cfg_hooks
= {
4701 tree_verify_flow_info
,
4702 tree_dump_bb
, /* dump_bb */
4703 create_bb
, /* create_basic_block */
4704 tree_redirect_edge_and_branch
,/* redirect_edge_and_branch */
4705 tree_redirect_edge_and_branch_force
,/* redirect_edge_and_branch_force */
4706 remove_bb
, /* delete_basic_block */
4707 tree_split_block
, /* split_block */
4708 tree_move_block_after
, /* move_block_after */
4709 tree_can_merge_blocks_p
, /* can_merge_blocks_p */
4710 tree_merge_blocks
, /* merge_blocks */
4711 tree_predict_edge
, /* predict_edge */
4712 tree_predicted_by_p
, /* predicted_by_p */
4713 tree_can_duplicate_bb_p
, /* can_duplicate_block_p */
4714 tree_duplicate_bb
, /* duplicate_block */
4715 tree_split_edge
, /* split_edge */
4716 tree_make_forwarder_block
, /* make_forward_block */
4717 NULL
, /* tidy_fallthru_edge */
4718 tree_block_ends_with_call_p
, /* block_ends_with_call_p */
4719 tree_block_ends_with_condjump_p
, /* block_ends_with_condjump_p */
4720 tree_flow_call_edges_add
/* flow_call_edges_add */
4724 /* Split all critical edges. */
4727 split_critical_edges (void)
4734 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
4735 if (EDGE_CRITICAL_P (e
) && !(e
->flags
& EDGE_ABNORMAL
))
4742 struct tree_opt_pass pass_split_crit_edges
=
4744 "crited", /* name */
4746 split_critical_edges
, /* execute */
4749 0, /* static_pass_number */
4750 TV_TREE_SPLIT_EDGES
, /* tv_id */
4751 PROP_cfg
, /* properties required */
4752 PROP_no_crit_edges
, /* properties_provided */
4753 0, /* properties_destroyed */
4754 0, /* todo_flags_start */
4755 TODO_dump_func
, /* todo_flags_finish */
4759 /* Return EXP if it is a valid GIMPLE rvalue, else gimplify it into
4760 a temporary, make sure and register it to be renamed if necessary,
4761 and finally return the temporary. Put the statements to compute
4762 EXP before the current statement in BSI. */
4765 gimplify_val (block_stmt_iterator
*bsi
, tree type
, tree exp
)
4767 tree t
, new_stmt
, orig_stmt
;
4769 if (is_gimple_val (exp
))
4772 t
= make_rename_temp (type
, NULL
);
4773 new_stmt
= build (MODIFY_EXPR
, type
, t
, exp
);
4775 orig_stmt
= bsi_stmt (*bsi
);
4776 SET_EXPR_LOCUS (new_stmt
, EXPR_LOCUS (orig_stmt
));
4777 TREE_BLOCK (new_stmt
) = TREE_BLOCK (orig_stmt
);
4779 bsi_insert_before (bsi
, new_stmt
, BSI_SAME_STMT
);
4784 /* Build a ternary operation and gimplify it. Emit code before BSI.
4785 Return the gimple_val holding the result. */
4788 gimplify_build3 (block_stmt_iterator
*bsi
, enum tree_code code
,
4789 tree type
, tree a
, tree b
, tree c
)
4793 ret
= fold (build3 (code
, type
, a
, b
, c
));
4796 return gimplify_val (bsi
, type
, ret
);
4799 /* Build a binary operation and gimplify it. Emit code before BSI.
4800 Return the gimple_val holding the result. */
4803 gimplify_build2 (block_stmt_iterator
*bsi
, enum tree_code code
,
4804 tree type
, tree a
, tree b
)
4808 ret
= fold (build2 (code
, type
, a
, b
));
4811 return gimplify_val (bsi
, type
, ret
);
4814 /* Build a unary operation and gimplify it. Emit code before BSI.
4815 Return the gimple_val holding the result. */
4818 gimplify_build1 (block_stmt_iterator
*bsi
, enum tree_code code
, tree type
,
4823 ret
= fold (build1 (code
, type
, a
));
4826 return gimplify_val (bsi
, type
, ret
);
4831 /* Emit return warnings. */
4834 execute_warn_function_return (void)
4836 #ifdef USE_MAPPED_LOCATION
4837 source_location location
;
4844 if (warn_missing_noreturn
4845 && !TREE_THIS_VOLATILE (cfun
->decl
)
4846 && EXIT_BLOCK_PTR
->pred
== NULL
4847 && !lang_hooks
.function
.missing_noreturn_ok_p (cfun
->decl
))
4848 warning ("%Jfunction might be possible candidate for attribute `noreturn'",
4851 /* If we have a path to EXIT, then we do return. */
4852 if (TREE_THIS_VOLATILE (cfun
->decl
)
4853 && EXIT_BLOCK_PTR
->pred
!= NULL
)
4855 #ifdef USE_MAPPED_LOCATION
4856 location
= UNKNOWN_LOCATION
;
4860 for (e
= EXIT_BLOCK_PTR
->pred
; e
; e
= e
->pred_next
)
4862 last
= last_stmt (e
->src
);
4863 if (TREE_CODE (last
) == RETURN_EXPR
4864 #ifdef USE_MAPPED_LOCATION
4865 && (location
= EXPR_LOCATION (last
)) != UNKNOWN_LOCATION
)
4867 && (locus
= EXPR_LOCUS (last
)) != NULL
)
4871 #ifdef USE_MAPPED_LOCATION
4872 if (location
== UNKNOWN_LOCATION
)
4873 location
= cfun
->function_end_locus
;
4874 warning ("%H`noreturn' function does return", &location
);
4877 locus
= &cfun
->function_end_locus
;
4878 warning ("%H`noreturn' function does return", locus
);
4882 /* If we see "return;" in some basic block, then we do reach the end
4883 without returning a value. */
4884 else if (warn_return_type
4885 && EXIT_BLOCK_PTR
->pred
!= NULL
4886 && !VOID_TYPE_P (TREE_TYPE (TREE_TYPE (cfun
->decl
))))
4888 for (e
= EXIT_BLOCK_PTR
->pred
; e
; e
= e
->pred_next
)
4890 tree last
= last_stmt (e
->src
);
4891 if (TREE_CODE (last
) == RETURN_EXPR
4892 && TREE_OPERAND (last
, 0) == NULL
)
4894 #ifdef USE_MAPPED_LOCATION
4895 location
= EXPR_LOCATION (last
);
4896 if (location
== UNKNOWN_LOCATION
)
4897 location
= cfun
->function_end_locus
;
4898 warning ("%Hcontrol reaches end of non-void function", &location
);
4900 locus
= EXPR_LOCUS (last
);
4902 locus
= &cfun
->function_end_locus
;
4903 warning ("%Hcontrol reaches end of non-void function", locus
);
4912 /* Given a basic block B which ends with a conditional and has
4913 precisely two successors, determine which of the edges is taken if
4914 the conditional is true and which is taken if the conditional is
4915 false. Set TRUE_EDGE and FALSE_EDGE appropriately. */
4918 extract_true_false_edges_from_block (basic_block b
,
4924 if (e
->flags
& EDGE_TRUE_VALUE
)
4927 *false_edge
= e
->succ_next
;
4932 *true_edge
= e
->succ_next
;
4936 struct tree_opt_pass pass_warn_function_return
=
4940 execute_warn_function_return
, /* execute */
4943 0, /* static_pass_number */
4945 PROP_cfg
, /* properties_required */
4946 0, /* properties_provided */
4947 0, /* properties_destroyed */
4948 0, /* todo_flags_start */
4949 0 /* todo_flags_finish */
4952 #include "gt-tree-cfg.h"