1 /* Control flow functions for trees.
2 Copyright (C) 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
3 Contributed by Diego Novillo <dnovillo@redhat.com>
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 GCC is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to
19 the Free Software Foundation, 59 Temple Place - Suite 330,
20 Boston, MA 02111-1307, USA. */
24 #include "coretypes.h"
29 #include "hard-reg-set.h"
30 #include "basic-block.h"
37 #include "langhooks.h"
38 #include "diagnostic.h"
39 #include "tree-flow.h"
41 #include "tree-dump.h"
42 #include "tree-pass.h"
47 /* This file contains functions for building the Control Flow Graph (CFG)
48 for a function tree. */
50 /* Local declarations. */
52 /* Initial capacity for the basic block array. */
53 static const int initial_cfg_capacity
= 20;
55 /* Mapping of labels to their associated blocks. This can greatly speed up
56 building of the CFG in code with lots of gotos. */
57 static GTY(()) varray_type label_to_block_map
;
62 long num_merged_labels
;
65 static struct cfg_stats_d cfg_stats
;
67 /* Nonzero if we found a computed goto while building basic blocks. */
68 static bool found_computed_goto
;
70 /* Basic blocks and flowgraphs. */
71 static basic_block
create_bb (void *, void *, basic_block
);
72 static void create_block_annotation (basic_block
);
73 static void free_blocks_annotations (void);
74 static void clear_blocks_annotations (void);
75 static void make_blocks (tree
);
76 static void factor_computed_gotos (void);
79 static void make_edges (void);
80 static void make_ctrl_stmt_edges (basic_block
);
81 static void make_exit_edges (basic_block
);
82 static void make_cond_expr_edges (basic_block
);
83 static void make_switch_expr_edges (basic_block
);
84 static void make_goto_expr_edges (basic_block
);
85 static edge
tree_redirect_edge_and_branch (edge
, basic_block
);
86 static edge
tree_try_redirect_by_replacing_jump (edge
, basic_block
);
87 static void split_critical_edges (void);
89 /* Various helpers. */
90 static inline bool stmt_starts_bb_p (tree
, tree
);
91 static int tree_verify_flow_info (void);
92 static void tree_make_forwarder_block (edge
);
93 static bool thread_jumps (void);
94 static bool tree_forwarder_block_p (basic_block
);
95 static void bsi_commit_edge_inserts_1 (edge e
);
96 static void tree_cfg2vcg (FILE *);
98 /* Flowgraph optimization and cleanup. */
99 static void tree_merge_blocks (basic_block
, basic_block
);
100 static bool tree_can_merge_blocks_p (basic_block
, basic_block
);
101 static void remove_bb (basic_block
);
102 static void group_case_labels (void);
103 static void cleanup_dead_labels (void);
104 static bool cleanup_control_flow (void);
105 static bool cleanup_control_expr_graph (basic_block
, block_stmt_iterator
);
106 static edge
find_taken_edge_cond_expr (basic_block
, tree
);
107 static edge
find_taken_edge_switch_expr (basic_block
, tree
);
108 static tree
find_case_label_for_value (tree
, tree
);
109 static bool phi_alternatives_equal (basic_block
, edge
, edge
);
112 /*---------------------------------------------------------------------------
114 ---------------------------------------------------------------------------*/
116 /* Entry point to the CFG builder for trees. TP points to the list of
117 statements to be added to the flowgraph. */
120 build_tree_cfg (tree
*tp
)
122 /* Register specific tree functions. */
123 tree_register_cfg_hooks ();
125 /* Initialize rbi_pool. */
128 /* Initialize the basic block array. */
131 last_basic_block
= 0;
132 VARRAY_BB_INIT (basic_block_info
, initial_cfg_capacity
, "basic_block_info");
133 memset ((void *) &cfg_stats
, 0, sizeof (cfg_stats
));
135 /* Build a mapping of labels to their associated blocks. */
136 VARRAY_BB_INIT (label_to_block_map
, initial_cfg_capacity
,
137 "label to block map");
139 ENTRY_BLOCK_PTR
->next_bb
= EXIT_BLOCK_PTR
;
140 EXIT_BLOCK_PTR
->prev_bb
= ENTRY_BLOCK_PTR
;
142 found_computed_goto
= 0;
145 /* Computed gotos are hell to deal with, especially if there are
146 lots of them with a large number of destinations. So we factor
147 them to a common computed goto location before we build the
148 edge list. After we convert back to normal form, we will un-factor
149 the computed gotos since factoring introduces an unwanted jump. */
150 if (found_computed_goto
)
151 factor_computed_gotos ();
153 /* Make sure there is always at least one block, even if its empty. */
154 if (n_basic_blocks
== 0)
155 create_empty_bb (ENTRY_BLOCK_PTR
);
157 create_block_annotation (ENTRY_BLOCK_PTR
);
158 create_block_annotation (EXIT_BLOCK_PTR
);
160 /* Adjust the size of the array. */
161 VARRAY_GROW (basic_block_info
, n_basic_blocks
);
163 /* To speed up statement iterator walks, we first purge dead labels. */
164 cleanup_dead_labels ();
166 /* Group case nodes to reduce the number of edges.
167 We do this after cleaning up dead labels because otherwise we miss
168 a lot of obvious case merging opportunities. */
169 group_case_labels ();
171 /* Create the edges of the flowgraph. */
174 /* Debugging dumps. */
176 /* Write the flowgraph to a VCG file. */
178 int local_dump_flags
;
179 FILE *dump_file
= dump_begin (TDI_vcg
, &local_dump_flags
);
182 tree_cfg2vcg (dump_file
);
183 dump_end (TDI_vcg
, dump_file
);
187 /* Dump a textual representation of the flowgraph. */
189 dump_tree_cfg (dump_file
, dump_flags
);
193 execute_build_cfg (void)
195 build_tree_cfg (&DECL_SAVED_TREE (current_function_decl
));
198 struct tree_opt_pass pass_build_cfg
=
202 execute_build_cfg
, /* execute */
205 0, /* static_pass_number */
206 TV_TREE_CFG
, /* tv_id */
207 PROP_gimple_leh
, /* properties_required */
208 PROP_cfg
, /* properties_provided */
209 0, /* properties_destroyed */
210 0, /* todo_flags_start */
211 TODO_verify_stmts
/* todo_flags_finish */
214 /* Search the CFG for any computed gotos. If found, factor them to a
215 common computed goto site. Also record the location of that site so
216 that we can un-factor the gotos after we have converted back to
220 factor_computed_gotos (void)
223 tree factored_label_decl
= NULL
;
225 tree factored_computed_goto_label
= NULL
;
226 tree factored_computed_goto
= NULL
;
228 /* We know there are one or more computed gotos in this function.
229 Examine the last statement in each basic block to see if the block
230 ends with a computed goto. */
234 block_stmt_iterator bsi
= bsi_last (bb
);
239 last
= bsi_stmt (bsi
);
241 /* Ignore the computed goto we create when we factor the original
243 if (last
== factored_computed_goto
)
246 /* If the last statement is a computed goto, factor it. */
247 if (computed_goto_p (last
))
251 /* The first time we find a computed goto we need to create
252 the factored goto block and the variable each original
253 computed goto will use for their goto destination. */
254 if (! factored_computed_goto
)
256 basic_block new_bb
= create_empty_bb (bb
);
257 block_stmt_iterator new_bsi
= bsi_start (new_bb
);
259 /* Create the destination of the factored goto. Each original
260 computed goto will put its desired destination into this
261 variable and jump to the label we create immediately
263 var
= create_tmp_var (ptr_type_node
, "gotovar");
265 /* Build a label for the new block which will contain the
266 factored computed goto. */
267 factored_label_decl
= create_artificial_label ();
268 factored_computed_goto_label
269 = build1 (LABEL_EXPR
, void_type_node
, factored_label_decl
);
270 bsi_insert_after (&new_bsi
, factored_computed_goto_label
,
273 /* Build our new computed goto. */
274 factored_computed_goto
= build1 (GOTO_EXPR
, void_type_node
, var
);
275 bsi_insert_after (&new_bsi
, factored_computed_goto
,
279 /* Copy the original computed goto's destination into VAR. */
280 assignment
= build (MODIFY_EXPR
, ptr_type_node
,
281 var
, GOTO_DESTINATION (last
));
282 bsi_insert_before (&bsi
, assignment
, BSI_SAME_STMT
);
284 /* And re-vector the computed goto to the new destination. */
285 GOTO_DESTINATION (last
) = factored_label_decl
;
291 /* Create annotations for a single basic block. */
294 create_block_annotation (basic_block bb
)
296 /* Verify that the tree_annotations field is clear. */
297 if (bb
->tree_annotations
)
299 bb
->tree_annotations
= ggc_alloc_cleared (sizeof (struct bb_ann_d
));
303 /* Free the annotations for all the basic blocks. */
305 static void free_blocks_annotations (void)
307 clear_blocks_annotations ();
311 /* Clear the annotations for all the basic blocks. */
314 clear_blocks_annotations (void)
318 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
, NULL
, next_bb
)
319 bb
->tree_annotations
= NULL
;
323 /* Build a flowgraph for the statement_list STMT_LIST. */
326 make_blocks (tree stmt_list
)
328 tree_stmt_iterator i
= tsi_start (stmt_list
);
330 bool start_new_block
= true;
331 bool first_stmt_of_list
= true;
332 basic_block bb
= ENTRY_BLOCK_PTR
;
334 while (!tsi_end_p (i
))
341 /* If the statement starts a new basic block or if we have determined
342 in a previous pass that we need to create a new block for STMT, do
344 if (start_new_block
|| stmt_starts_bb_p (stmt
, prev_stmt
))
346 if (!first_stmt_of_list
)
347 stmt_list
= tsi_split_statement_list_before (&i
);
348 bb
= create_basic_block (stmt_list
, NULL
, bb
);
349 start_new_block
= false;
352 /* Now add STMT to BB and create the subgraphs for special statement
354 set_bb_for_stmt (stmt
, bb
);
356 if (computed_goto_p (stmt
))
357 found_computed_goto
= true;
359 /* If STMT is a basic block terminator, set START_NEW_BLOCK for the
361 if (stmt_ends_bb_p (stmt
))
362 start_new_block
= true;
365 first_stmt_of_list
= false;
370 /* Create and return a new empty basic block after bb AFTER. */
373 create_bb (void *h
, void *e
, basic_block after
)
380 /* Create and initialize a new basic block. */
382 memset (bb
, 0, sizeof (*bb
));
384 bb
->index
= last_basic_block
;
386 bb
->stmt_list
= h
? h
: alloc_stmt_list ();
388 /* Add the new block to the linked list of blocks. */
389 link_block (bb
, after
);
391 /* Grow the basic block array if needed. */
392 if ((size_t) last_basic_block
== VARRAY_SIZE (basic_block_info
))
394 size_t new_size
= last_basic_block
+ (last_basic_block
+ 3) / 4;
395 VARRAY_GROW (basic_block_info
, new_size
);
398 /* Add the newly created block to the array. */
399 BASIC_BLOCK (last_basic_block
) = bb
;
401 create_block_annotation (bb
);
406 initialize_bb_rbi (bb
);
411 /*---------------------------------------------------------------------------
413 ---------------------------------------------------------------------------*/
415 /* Join all the blocks in the flowgraph. */
422 /* Create an edge from entry to the first block with executable
424 make_edge (ENTRY_BLOCK_PTR
, BASIC_BLOCK (0), EDGE_FALLTHRU
);
426 /* Traverse basic block array placing edges. */
429 tree first
= first_stmt (bb
);
430 tree last
= last_stmt (bb
);
434 /* Edges for statements that always alter flow control. */
435 if (is_ctrl_stmt (last
))
436 make_ctrl_stmt_edges (bb
);
438 /* Edges for statements that sometimes alter flow control. */
439 if (is_ctrl_altering_stmt (last
))
440 make_exit_edges (bb
);
443 /* Finally, if no edges were created above, this is a regular
444 basic block that only needs a fallthru edge. */
445 if (bb
->succ
== NULL
)
446 make_edge (bb
, bb
->next_bb
, EDGE_FALLTHRU
);
449 /* We do not care about fake edges, so remove any that the CFG
450 builder inserted for completeness. */
451 remove_fake_edges ();
453 /* Clean up the graph and warn for unreachable code. */
458 /* Create edges for control statement at basic block BB. */
461 make_ctrl_stmt_edges (basic_block bb
)
463 tree last
= last_stmt (bb
);
464 tree first
= first_stmt (bb
);
466 #if defined ENABLE_CHECKING
467 if (last
== NULL_TREE
)
471 if (TREE_CODE (first
) == LABEL_EXPR
472 && DECL_NONLOCAL (LABEL_EXPR_LABEL (first
)))
473 make_edge (ENTRY_BLOCK_PTR
, bb
, EDGE_ABNORMAL
);
475 switch (TREE_CODE (last
))
478 make_goto_expr_edges (bb
);
482 make_edge (bb
, EXIT_BLOCK_PTR
, 0);
486 make_cond_expr_edges (bb
);
490 make_switch_expr_edges (bb
);
494 make_eh_edges (last
);
495 /* Yet another NORETURN hack. */
496 if (bb
->succ
== NULL
)
497 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
506 /* Create exit edges for statements in block BB that alter the flow of
507 control. Statements that alter the control flow are 'goto', 'return'
508 and calls to non-returning functions. */
511 make_exit_edges (basic_block bb
)
513 tree last
= last_stmt (bb
);
515 if (last
== NULL_TREE
)
518 switch (TREE_CODE (last
))
521 /* If this function receives a nonlocal goto, then we need to
522 make edges from this call site to all the nonlocal goto
524 if (TREE_SIDE_EFFECTS (last
)
525 && current_function_has_nonlocal_label
)
526 make_goto_expr_edges (bb
);
528 /* If this statement has reachable exception handlers, then
529 create abnormal edges to them. */
530 make_eh_edges (last
);
532 /* Some calls are known not to return. For such calls we create
535 We really need to revamp how we build edges so that it's not
536 such a bloody pain to avoid creating edges for this case since
537 all we do is remove these edges when we're done building the
539 if (call_expr_flags (last
) & (ECF_NORETURN
| ECF_LONGJMP
))
541 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
545 /* Don't forget the fall-thru edge. */
546 make_edge (bb
, bb
->next_bb
, EDGE_FALLTHRU
);
550 /* A MODIFY_EXPR may have a CALL_EXPR on its RHS and the CALL_EXPR
551 may have an abnormal edge. Search the RHS for this case and
552 create any required edges. */
553 if (TREE_CODE (TREE_OPERAND (last
, 1)) == CALL_EXPR
554 && TREE_SIDE_EFFECTS (TREE_OPERAND (last
, 1))
555 && current_function_has_nonlocal_label
)
556 make_goto_expr_edges (bb
);
558 make_eh_edges (last
);
559 make_edge (bb
, bb
->next_bb
, EDGE_FALLTHRU
);
568 /* Create the edges for a COND_EXPR starting at block BB.
569 At this point, both clauses must contain only simple gotos. */
572 make_cond_expr_edges (basic_block bb
)
574 tree entry
= last_stmt (bb
);
575 basic_block then_bb
, else_bb
;
576 tree then_label
, else_label
;
578 #if defined ENABLE_CHECKING
579 if (entry
== NULL_TREE
|| TREE_CODE (entry
) != COND_EXPR
)
583 /* Entry basic blocks for each component. */
584 then_label
= GOTO_DESTINATION (COND_EXPR_THEN (entry
));
585 else_label
= GOTO_DESTINATION (COND_EXPR_ELSE (entry
));
586 then_bb
= label_to_block (then_label
);
587 else_bb
= label_to_block (else_label
);
589 make_edge (bb
, then_bb
, EDGE_TRUE_VALUE
);
590 make_edge (bb
, else_bb
, EDGE_FALSE_VALUE
);
594 /* Create the edges for a SWITCH_EXPR starting at block BB.
595 At this point, the switch body has been lowered and the
596 SWITCH_LABELS filled in, so this is in effect a multi-way branch. */
599 make_switch_expr_edges (basic_block bb
)
601 tree entry
= last_stmt (bb
);
605 vec
= SWITCH_LABELS (entry
);
606 n
= TREE_VEC_LENGTH (vec
);
608 for (i
= 0; i
< n
; ++i
)
610 tree lab
= CASE_LABEL (TREE_VEC_ELT (vec
, i
));
611 basic_block label_bb
= label_to_block (lab
);
612 make_edge (bb
, label_bb
, 0);
617 /* Return the basic block holding label DEST. */
620 label_to_block (tree dest
)
622 int uid
= LABEL_DECL_UID (dest
);
624 /* We would die hard when faced by undefined label. Emit label to
625 very first basic block. This will hopefully make even the dataflow
626 and undefined variable warnings quite right. */
627 if ((errorcount
|| sorrycount
) && uid
< 0)
629 block_stmt_iterator bsi
= bsi_start (BASIC_BLOCK (0));
632 stmt
= build1 (LABEL_EXPR
, void_type_node
, dest
);
633 bsi_insert_before (&bsi
, stmt
, BSI_NEW_STMT
);
634 uid
= LABEL_DECL_UID (dest
);
636 return VARRAY_BB (label_to_block_map
, uid
);
640 /* Create edges for a goto statement at block BB. */
643 make_goto_expr_edges (basic_block bb
)
646 basic_block target_bb
;
648 block_stmt_iterator last
= bsi_last (bb
);
650 goto_t
= bsi_stmt (last
);
652 /* If the last statement is not a GOTO (i.e., it is a RETURN_EXPR,
653 CALL_EXPR or MODIFY_EXPR), then the edge is an abnormal edge resulting
654 from a nonlocal goto. */
655 if (TREE_CODE (goto_t
) != GOTO_EXPR
)
657 dest
= error_mark_node
;
662 dest
= GOTO_DESTINATION (goto_t
);
665 /* A GOTO to a local label creates normal edges. */
666 if (simple_goto_p (goto_t
))
668 edge e
= make_edge (bb
, label_to_block (dest
), EDGE_FALLTHRU
);
669 #ifdef USE_MAPPED_LOCATION
670 e
->goto_locus
= EXPR_LOCATION (goto_t
);
672 e
->goto_locus
= EXPR_LOCUS (goto_t
);
678 /* Nothing more to do for nonlocal gotos. */
679 if (TREE_CODE (dest
) == LABEL_DECL
)
682 /* Computed gotos remain. */
685 /* Look for the block starting with the destination label. In the
686 case of a computed goto, make an edge to any label block we find
688 FOR_EACH_BB (target_bb
)
690 block_stmt_iterator bsi
;
692 for (bsi
= bsi_start (target_bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
694 tree target
= bsi_stmt (bsi
);
696 if (TREE_CODE (target
) != LABEL_EXPR
)
700 /* Computed GOTOs. Make an edge to every label block that has
701 been marked as a potential target for a computed goto. */
702 (FORCED_LABEL (LABEL_EXPR_LABEL (target
)) && for_call
== 0)
703 /* Nonlocal GOTO target. Make an edge to every label block
704 that has been marked as a potential target for a nonlocal
706 || (DECL_NONLOCAL (LABEL_EXPR_LABEL (target
)) && for_call
== 1))
708 make_edge (bb
, target_bb
, EDGE_ABNORMAL
);
714 /* Degenerate case of computed goto with no labels. */
715 if (!for_call
&& !bb
->succ
)
716 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
720 /*---------------------------------------------------------------------------
722 ---------------------------------------------------------------------------*/
724 /* Remove unreachable blocks and other miscellaneous clean up work. */
727 cleanup_tree_cfg (void)
729 bool something_changed
= true;
731 timevar_push (TV_TREE_CLEANUP_CFG
);
733 /* These three transformations can cascade, so we iterate on them until
735 while (something_changed
)
737 something_changed
= cleanup_control_flow ();
738 something_changed
|= thread_jumps ();
739 something_changed
|= delete_unreachable_blocks ();
742 /* Merging the blocks creates no new opportunities for the other
743 optimizations, so do it here. */
748 #ifdef ENABLE_CHECKING
751 timevar_pop (TV_TREE_CLEANUP_CFG
);
755 /* Cleanup useless labels in basic blocks. This is something we wish
756 to do early because it allows us to group case labels before creating
757 the edges for the CFG, and it speeds up block statement iterators in
759 We only run this pass once, running it more than once is probably not
762 /* A map from basic block index to the leading label of that block. */
763 static tree
*label_for_bb
;
765 /* Callback for for_each_eh_region. Helper for cleanup_dead_labels. */
767 update_eh_label (struct eh_region
*region
)
769 tree old_label
= get_eh_region_tree_label (region
);
772 tree new_label
= label_for_bb
[label_to_block (old_label
)->index
];
773 set_eh_region_tree_label (region
, new_label
);
777 /* Given LABEL return the first label in the same basic block. */
779 main_block_label (tree label
)
781 basic_block bb
= label_to_block (label
);
783 /* label_to_block possibly inserted undefined label into the chain. */
784 if (!label_for_bb
[bb
->index
])
785 label_for_bb
[bb
->index
] = label
;
786 return label_for_bb
[bb
->index
];
789 /* Cleanup redundant labels. This is a three-steo process:
790 1) Find the leading label for each block.
791 2) Redirect all references to labels to the leading labels.
792 3) Cleanup all useless labels. */
795 cleanup_dead_labels (void)
798 label_for_bb
= xcalloc (last_basic_block
, sizeof (tree
));
800 /* Find a suitable label for each block. We use the first user-defined
801 label is there is one, or otherwise just the first label we see. */
804 block_stmt_iterator i
;
806 for (i
= bsi_start (bb
); !bsi_end_p (i
); bsi_next (&i
))
808 tree label
, stmt
= bsi_stmt (i
);
810 if (TREE_CODE (stmt
) != LABEL_EXPR
)
813 label
= LABEL_EXPR_LABEL (stmt
);
815 /* If we have not yet seen a label for the current block,
816 remember this one and see if there are more labels. */
817 if (! label_for_bb
[bb
->index
])
819 label_for_bb
[bb
->index
] = label
;
823 /* If we did see a label for the current block already, but it
824 is an artificially created label, replace it if the current
825 label is a user defined label. */
826 if (! DECL_ARTIFICIAL (label
)
827 && DECL_ARTIFICIAL (label_for_bb
[bb
->index
]))
829 label_for_bb
[bb
->index
] = label
;
835 /* Now redirect all jumps/branches to the selected label.
836 First do so for each block ending in a control statement. */
839 tree stmt
= last_stmt (bb
);
843 switch (TREE_CODE (stmt
))
847 tree true_branch
, false_branch
;
849 true_branch
= COND_EXPR_THEN (stmt
);
850 false_branch
= COND_EXPR_ELSE (stmt
);
852 GOTO_DESTINATION (true_branch
)
853 = main_block_label (GOTO_DESTINATION (true_branch
));
854 GOTO_DESTINATION (false_branch
)
855 = main_block_label (GOTO_DESTINATION (false_branch
));
863 tree vec
= SWITCH_LABELS (stmt
);
864 size_t n
= TREE_VEC_LENGTH (vec
);
866 /* Replace all destination labels. */
867 for (i
= 0; i
< n
; ++i
)
868 CASE_LABEL (TREE_VEC_ELT (vec
, i
))
869 = main_block_label (CASE_LABEL (TREE_VEC_ELT (vec
, i
)));
874 /* We have to handle GOTO_EXPRs until they're removed, and we don't
875 remove them until after we've created the CFG edges. */
877 if (! computed_goto_p (stmt
))
879 GOTO_DESTINATION (stmt
)
880 = main_block_label (GOTO_DESTINATION (stmt
));
889 for_each_eh_region (update_eh_label
);
891 /* Finally, purge dead labels. All user-defined labels and labels that
892 can be the target of non-local gotos are preserved. */
895 block_stmt_iterator i
;
896 tree label_for_this_bb
= label_for_bb
[bb
->index
];
898 if (! label_for_this_bb
)
901 for (i
= bsi_start (bb
); !bsi_end_p (i
); )
903 tree label
, stmt
= bsi_stmt (i
);
905 if (TREE_CODE (stmt
) != LABEL_EXPR
)
908 label
= LABEL_EXPR_LABEL (stmt
);
910 if (label
== label_for_this_bb
911 || ! DECL_ARTIFICIAL (label
)
912 || DECL_NONLOCAL (label
))
922 /* Look for blocks ending in a multiway branch (a SWITCH_EXPR in GIMPLE),
923 and scan the sorted vector of cases. Combine the ones jumping to the
925 Eg. three separate entries 1: 2: 3: become one entry 1..3: */
928 group_case_labels (void)
934 tree stmt
= last_stmt (bb
);
935 if (stmt
&& TREE_CODE (stmt
) == SWITCH_EXPR
)
937 tree labels
= SWITCH_LABELS (stmt
);
938 int old_size
= TREE_VEC_LENGTH (labels
);
939 int i
, j
, new_size
= old_size
;
941 /* Look for possible opportunities to merge cases.
942 Ignore the last element of the label vector because it
943 must be the default case. */
945 while (i
< old_size
- 2)
947 tree base_case
, base_label
, base_high
, type
;
948 base_case
= TREE_VEC_ELT (labels
, i
);
953 type
= TREE_TYPE (CASE_LOW (base_case
));
954 base_label
= CASE_LABEL (base_case
);
955 base_high
= CASE_HIGH (base_case
) ?
956 CASE_HIGH (base_case
) : CASE_LOW (base_case
);
958 /* Try to merge case labels. Break out when we reach the end
959 of the label vector or when we cannot merge the next case
960 label with the current one. */
961 while (i
< old_size
- 2)
963 tree merge_case
= TREE_VEC_ELT (labels
, ++i
);
964 tree merge_label
= CASE_LABEL (merge_case
);
965 tree t
= int_const_binop (PLUS_EXPR
, base_high
,
966 integer_one_node
, 1);
968 /* Merge the cases if they jump to the same place,
969 and their ranges are consecutive. */
970 if (merge_label
== base_label
971 && tree_int_cst_equal (CASE_LOW (merge_case
), t
))
973 base_high
= CASE_HIGH (merge_case
) ?
974 CASE_HIGH (merge_case
) : CASE_LOW (merge_case
);
975 CASE_HIGH (base_case
) = base_high
;
976 TREE_VEC_ELT (labels
, i
) = NULL_TREE
;
984 /* Compress the case labels in the label vector, and adjust the
985 length of the vector. */
986 for (i
= 0, j
= 0; i
< new_size
; i
++)
988 while (! TREE_VEC_ELT (labels
, j
))
990 TREE_VEC_ELT (labels
, i
) = TREE_VEC_ELT (labels
, j
++);
992 TREE_VEC_LENGTH (labels
) = new_size
;
997 /* Checks whether we can merge block B into block A. */
1000 tree_can_merge_blocks_p (basic_block a
, basic_block b
)
1003 block_stmt_iterator bsi
;
1006 || a
->succ
->succ_next
)
1009 if (a
->succ
->flags
& EDGE_ABNORMAL
)
1012 if (a
->succ
->dest
!= b
)
1015 if (b
== EXIT_BLOCK_PTR
)
1018 if (b
->pred
->pred_next
)
1021 /* If A ends by a statement causing exceptions or something similar, we
1022 cannot merge the blocks. */
1023 stmt
= last_stmt (a
);
1024 if (stmt
&& stmt_ends_bb_p (stmt
))
1027 /* Do not allow a block with only a non-local label to be merged. */
1028 if (stmt
&& TREE_CODE (stmt
) == LABEL_EXPR
1029 && DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt
)))
1032 /* There may be no phi nodes at the start of b. Most of these degenerate
1033 phi nodes should be cleaned up by kill_redundant_phi_nodes. */
1037 /* Do not remove user labels. */
1038 for (bsi
= bsi_start (b
); !bsi_end_p (bsi
); bsi_next (&bsi
))
1040 stmt
= bsi_stmt (bsi
);
1041 if (TREE_CODE (stmt
) != LABEL_EXPR
)
1043 if (!DECL_ARTIFICIAL (LABEL_EXPR_LABEL (stmt
)))
1051 /* Merge block B into block A. */
1054 tree_merge_blocks (basic_block a
, basic_block b
)
1056 block_stmt_iterator bsi
;
1057 tree_stmt_iterator last
;
1060 fprintf (dump_file
, "Merging blocks %d and %d\n", a
->index
, b
->index
);
1062 /* Ensure that B follows A. */
1063 move_block_after (b
, a
);
1065 if (!(a
->succ
->flags
& EDGE_FALLTHRU
))
1069 && stmt_ends_bb_p (last_stmt (a
)))
1072 /* Remove labels from B and set bb_for_stmt to A for other statements. */
1073 for (bsi
= bsi_start (b
); !bsi_end_p (bsi
);)
1075 if (TREE_CODE (bsi_stmt (bsi
)) == LABEL_EXPR
)
1079 set_bb_for_stmt (bsi_stmt (bsi
), a
);
1084 /* Merge the chains. */
1085 last
= tsi_last (a
->stmt_list
);
1086 tsi_link_after (&last
, b
->stmt_list
, TSI_NEW_STMT
);
1087 b
->stmt_list
= NULL
;
1091 /* Walk the function tree removing unnecessary statements.
1093 * Empty statement nodes are removed
1095 * Unnecessary TRY_FINALLY and TRY_CATCH blocks are removed
1097 * Unnecessary COND_EXPRs are removed
1099 * Some unnecessary BIND_EXPRs are removed
1101 Clearly more work could be done. The trick is doing the analysis
1102 and removal fast enough to be a net improvement in compile times.
1104 Note that when we remove a control structure such as a COND_EXPR
1105 BIND_EXPR, or TRY block, we will need to repeat this optimization pass
1106 to ensure we eliminate all the useless code. */
1117 static void remove_useless_stmts_1 (tree
*, struct rus_data
*);
1120 remove_useless_stmts_warn_notreached (tree stmt
)
1122 if (EXPR_HAS_LOCATION (stmt
))
1124 location_t loc
= EXPR_LOCATION (stmt
);
1125 warning ("%Hwill never be executed", &loc
);
1129 switch (TREE_CODE (stmt
))
1131 case STATEMENT_LIST
:
1133 tree_stmt_iterator i
;
1134 for (i
= tsi_start (stmt
); !tsi_end_p (i
); tsi_next (&i
))
1135 if (remove_useless_stmts_warn_notreached (tsi_stmt (i
)))
1141 if (remove_useless_stmts_warn_notreached (COND_EXPR_COND (stmt
)))
1143 if (remove_useless_stmts_warn_notreached (COND_EXPR_THEN (stmt
)))
1145 if (remove_useless_stmts_warn_notreached (COND_EXPR_ELSE (stmt
)))
1149 case TRY_FINALLY_EXPR
:
1150 case TRY_CATCH_EXPR
:
1151 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt
, 0)))
1153 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt
, 1)))
1158 return remove_useless_stmts_warn_notreached (CATCH_BODY (stmt
));
1159 case EH_FILTER_EXPR
:
1160 return remove_useless_stmts_warn_notreached (EH_FILTER_FAILURE (stmt
));
1162 return remove_useless_stmts_warn_notreached (BIND_EXPR_BLOCK (stmt
));
1165 /* Not a live container. */
1173 remove_useless_stmts_cond (tree
*stmt_p
, struct rus_data
*data
)
1175 tree then_clause
, else_clause
, cond
;
1176 bool save_has_label
, then_has_label
, else_has_label
;
1178 save_has_label
= data
->has_label
;
1179 data
->has_label
= false;
1180 data
->last_goto
= NULL
;
1182 remove_useless_stmts_1 (&COND_EXPR_THEN (*stmt_p
), data
);
1184 then_has_label
= data
->has_label
;
1185 data
->has_label
= false;
1186 data
->last_goto
= NULL
;
1188 remove_useless_stmts_1 (&COND_EXPR_ELSE (*stmt_p
), data
);
1190 else_has_label
= data
->has_label
;
1191 data
->has_label
= save_has_label
| then_has_label
| else_has_label
;
1194 then_clause
= COND_EXPR_THEN (*stmt_p
);
1195 else_clause
= COND_EXPR_ELSE (*stmt_p
);
1196 cond
= COND_EXPR_COND (*stmt_p
);
1198 /* If neither arm does anything at all, we can remove the whole IF. */
1199 if (!TREE_SIDE_EFFECTS (then_clause
) && !TREE_SIDE_EFFECTS (else_clause
))
1201 *stmt_p
= build_empty_stmt ();
1202 data
->repeat
= true;
1205 /* If there are no reachable statements in an arm, then we can
1206 zap the entire conditional. */
1207 else if (integer_nonzerop (cond
) && !else_has_label
)
1209 if (warn_notreached
)
1210 remove_useless_stmts_warn_notreached (else_clause
);
1211 *stmt_p
= then_clause
;
1212 data
->repeat
= true;
1214 else if (integer_zerop (cond
) && !then_has_label
)
1216 if (warn_notreached
)
1217 remove_useless_stmts_warn_notreached (then_clause
);
1218 *stmt_p
= else_clause
;
1219 data
->repeat
= true;
1222 /* Check a couple of simple things on then/else with single stmts. */
1225 tree then_stmt
= expr_only (then_clause
);
1226 tree else_stmt
= expr_only (else_clause
);
1228 /* Notice branches to a common destination. */
1229 if (then_stmt
&& else_stmt
1230 && TREE_CODE (then_stmt
) == GOTO_EXPR
1231 && TREE_CODE (else_stmt
) == GOTO_EXPR
1232 && (GOTO_DESTINATION (then_stmt
) == GOTO_DESTINATION (else_stmt
)))
1234 *stmt_p
= then_stmt
;
1235 data
->repeat
= true;
1238 /* If the THEN/ELSE clause merely assigns a value to a variable or
1239 parameter which is already known to contain that value, then
1240 remove the useless THEN/ELSE clause. */
1241 else if (TREE_CODE (cond
) == VAR_DECL
|| TREE_CODE (cond
) == PARM_DECL
)
1244 && TREE_CODE (else_stmt
) == MODIFY_EXPR
1245 && TREE_OPERAND (else_stmt
, 0) == cond
1246 && integer_zerop (TREE_OPERAND (else_stmt
, 1)))
1247 COND_EXPR_ELSE (*stmt_p
) = alloc_stmt_list ();
1249 else if ((TREE_CODE (cond
) == EQ_EXPR
|| TREE_CODE (cond
) == NE_EXPR
)
1250 && (TREE_CODE (TREE_OPERAND (cond
, 0)) == VAR_DECL
1251 || TREE_CODE (TREE_OPERAND (cond
, 0)) == PARM_DECL
)
1252 && TREE_CONSTANT (TREE_OPERAND (cond
, 1)))
1254 tree stmt
= (TREE_CODE (cond
) == EQ_EXPR
1255 ? then_stmt
: else_stmt
);
1256 tree
*location
= (TREE_CODE (cond
) == EQ_EXPR
1257 ? &COND_EXPR_THEN (*stmt_p
)
1258 : &COND_EXPR_ELSE (*stmt_p
));
1261 && TREE_CODE (stmt
) == MODIFY_EXPR
1262 && TREE_OPERAND (stmt
, 0) == TREE_OPERAND (cond
, 0)
1263 && TREE_OPERAND (stmt
, 1) == TREE_OPERAND (cond
, 1))
1264 *location
= alloc_stmt_list ();
1268 /* Protect GOTOs in the arm of COND_EXPRs from being removed. They
1269 would be re-introduced during lowering. */
1270 data
->last_goto
= NULL
;
1275 remove_useless_stmts_tf (tree
*stmt_p
, struct rus_data
*data
)
1277 bool save_may_branch
, save_may_throw
;
1278 bool this_may_branch
, this_may_throw
;
1280 /* Collect may_branch and may_throw information for the body only. */
1281 save_may_branch
= data
->may_branch
;
1282 save_may_throw
= data
->may_throw
;
1283 data
->may_branch
= false;
1284 data
->may_throw
= false;
1285 data
->last_goto
= NULL
;
1287 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p
, 0), data
);
1289 this_may_branch
= data
->may_branch
;
1290 this_may_throw
= data
->may_throw
;
1291 data
->may_branch
|= save_may_branch
;
1292 data
->may_throw
|= save_may_throw
;
1293 data
->last_goto
= NULL
;
1295 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p
, 1), data
);
1297 /* If the body is empty, then we can emit the FINALLY block without
1298 the enclosing TRY_FINALLY_EXPR. */
1299 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p
, 0)))
1301 *stmt_p
= TREE_OPERAND (*stmt_p
, 1);
1302 data
->repeat
= true;
1305 /* If the handler is empty, then we can emit the TRY block without
1306 the enclosing TRY_FINALLY_EXPR. */
1307 else if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p
, 1)))
1309 *stmt_p
= TREE_OPERAND (*stmt_p
, 0);
1310 data
->repeat
= true;
1313 /* If the body neither throws, nor branches, then we can safely
1314 string the TRY and FINALLY blocks together. */
1315 else if (!this_may_branch
&& !this_may_throw
)
1317 tree stmt
= *stmt_p
;
1318 *stmt_p
= TREE_OPERAND (stmt
, 0);
1319 append_to_statement_list (TREE_OPERAND (stmt
, 1), stmt_p
);
1320 data
->repeat
= true;
1326 remove_useless_stmts_tc (tree
*stmt_p
, struct rus_data
*data
)
1328 bool save_may_throw
, this_may_throw
;
1329 tree_stmt_iterator i
;
1332 /* Collect may_throw information for the body only. */
1333 save_may_throw
= data
->may_throw
;
1334 data
->may_throw
= false;
1335 data
->last_goto
= NULL
;
1337 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p
, 0), data
);
1339 this_may_throw
= data
->may_throw
;
1340 data
->may_throw
= save_may_throw
;
1342 /* If the body cannot throw, then we can drop the entire TRY_CATCH_EXPR. */
1343 if (!this_may_throw
)
1345 if (warn_notreached
)
1346 remove_useless_stmts_warn_notreached (TREE_OPERAND (*stmt_p
, 1));
1347 *stmt_p
= TREE_OPERAND (*stmt_p
, 0);
1348 data
->repeat
= true;
1352 /* Process the catch clause specially. We may be able to tell that
1353 no exceptions propagate past this point. */
1355 this_may_throw
= true;
1356 i
= tsi_start (TREE_OPERAND (*stmt_p
, 1));
1357 stmt
= tsi_stmt (i
);
1358 data
->last_goto
= NULL
;
1360 switch (TREE_CODE (stmt
))
1363 for (; !tsi_end_p (i
); tsi_next (&i
))
1365 stmt
= tsi_stmt (i
);
1366 /* If we catch all exceptions, then the body does not
1367 propagate exceptions past this point. */
1368 if (CATCH_TYPES (stmt
) == NULL
)
1369 this_may_throw
= false;
1370 data
->last_goto
= NULL
;
1371 remove_useless_stmts_1 (&CATCH_BODY (stmt
), data
);
1375 case EH_FILTER_EXPR
:
1376 if (EH_FILTER_MUST_NOT_THROW (stmt
))
1377 this_may_throw
= false;
1378 else if (EH_FILTER_TYPES (stmt
) == NULL
)
1379 this_may_throw
= false;
1380 remove_useless_stmts_1 (&EH_FILTER_FAILURE (stmt
), data
);
1384 /* Otherwise this is a cleanup. */
1385 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p
, 1), data
);
1387 /* If the cleanup is empty, then we can emit the TRY block without
1388 the enclosing TRY_CATCH_EXPR. */
1389 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p
, 1)))
1391 *stmt_p
= TREE_OPERAND (*stmt_p
, 0);
1392 data
->repeat
= true;
1396 data
->may_throw
|= this_may_throw
;
1401 remove_useless_stmts_bind (tree
*stmt_p
, struct rus_data
*data
)
1405 /* First remove anything underneath the BIND_EXPR. */
1406 remove_useless_stmts_1 (&BIND_EXPR_BODY (*stmt_p
), data
);
1408 /* If the BIND_EXPR has no variables, then we can pull everything
1409 up one level and remove the BIND_EXPR, unless this is the toplevel
1410 BIND_EXPR for the current function or an inlined function.
1412 When this situation occurs we will want to apply this
1413 optimization again. */
1414 block
= BIND_EXPR_BLOCK (*stmt_p
);
1415 if (BIND_EXPR_VARS (*stmt_p
) == NULL_TREE
1416 && *stmt_p
!= DECL_SAVED_TREE (current_function_decl
)
1418 || ! BLOCK_ABSTRACT_ORIGIN (block
)
1419 || (TREE_CODE (BLOCK_ABSTRACT_ORIGIN (block
))
1422 *stmt_p
= BIND_EXPR_BODY (*stmt_p
);
1423 data
->repeat
= true;
1429 remove_useless_stmts_goto (tree
*stmt_p
, struct rus_data
*data
)
1431 tree dest
= GOTO_DESTINATION (*stmt_p
);
1433 data
->may_branch
= true;
1434 data
->last_goto
= NULL
;
1436 /* Record the last goto expr, so that we can delete it if unnecessary. */
1437 if (TREE_CODE (dest
) == LABEL_DECL
)
1438 data
->last_goto
= stmt_p
;
1443 remove_useless_stmts_label (tree
*stmt_p
, struct rus_data
*data
)
1445 tree label
= LABEL_EXPR_LABEL (*stmt_p
);
1447 data
->has_label
= true;
1449 /* We do want to jump across non-local label receiver code. */
1450 if (DECL_NONLOCAL (label
))
1451 data
->last_goto
= NULL
;
1453 else if (data
->last_goto
&& GOTO_DESTINATION (*data
->last_goto
) == label
)
1455 *data
->last_goto
= build_empty_stmt ();
1456 data
->repeat
= true;
1459 /* ??? Add something here to delete unused labels. */
1463 /* If the function is "const" or "pure", then clear TREE_SIDE_EFFECTS on its
1464 decl. This allows us to eliminate redundant or useless
1465 calls to "const" functions.
1467 Gimplifier already does the same operation, but we may notice functions
1468 being const and pure once their calls has been gimplified, so we need
1469 to update the flag. */
1472 update_call_expr_flags (tree call
)
1474 tree decl
= get_callee_fndecl (call
);
1477 if (call_expr_flags (call
) & (ECF_CONST
| ECF_PURE
))
1478 TREE_SIDE_EFFECTS (call
) = 0;
1479 if (TREE_NOTHROW (decl
))
1480 TREE_NOTHROW (call
) = 1;
1484 /* T is CALL_EXPR. Set current_function_calls_* flags. */
1487 notice_special_calls (tree t
)
1489 int flags
= call_expr_flags (t
);
1491 if (flags
& ECF_MAY_BE_ALLOCA
)
1492 current_function_calls_alloca
= true;
1493 if (flags
& ECF_RETURNS_TWICE
)
1494 current_function_calls_setjmp
= true;
1498 /* Clear flags set by notice_special_calls. Used by dead code removal
1499 to update the flags. */
1502 clear_special_calls (void)
1504 current_function_calls_alloca
= false;
1505 current_function_calls_setjmp
= false;
1510 remove_useless_stmts_1 (tree
*tp
, struct rus_data
*data
)
1514 switch (TREE_CODE (t
))
1517 remove_useless_stmts_cond (tp
, data
);
1520 case TRY_FINALLY_EXPR
:
1521 remove_useless_stmts_tf (tp
, data
);
1524 case TRY_CATCH_EXPR
:
1525 remove_useless_stmts_tc (tp
, data
);
1529 remove_useless_stmts_bind (tp
, data
);
1533 remove_useless_stmts_goto (tp
, data
);
1537 remove_useless_stmts_label (tp
, data
);
1542 data
->last_goto
= NULL
;
1543 data
->may_branch
= true;
1548 data
->last_goto
= NULL
;
1549 notice_special_calls (t
);
1550 update_call_expr_flags (t
);
1551 if (tree_could_throw_p (t
))
1552 data
->may_throw
= true;
1556 data
->last_goto
= NULL
;
1558 if (TREE_CODE (TREE_OPERAND (t
, 1)) == CALL_EXPR
)
1560 update_call_expr_flags (TREE_OPERAND (t
, 1));
1561 notice_special_calls (TREE_OPERAND (t
, 1));
1563 if (tree_could_throw_p (t
))
1564 data
->may_throw
= true;
1567 case STATEMENT_LIST
:
1569 tree_stmt_iterator i
= tsi_start (t
);
1570 while (!tsi_end_p (i
))
1573 if (IS_EMPTY_STMT (t
))
1579 remove_useless_stmts_1 (tsi_stmt_ptr (i
), data
);
1582 if (TREE_CODE (t
) == STATEMENT_LIST
)
1584 tsi_link_before (&i
, t
, TSI_SAME_STMT
);
1594 data
->last_goto
= NULL
;
1598 data
->last_goto
= NULL
;
1604 remove_useless_stmts (void)
1606 struct rus_data data
;
1608 clear_special_calls ();
1612 memset (&data
, 0, sizeof (data
));
1613 remove_useless_stmts_1 (&DECL_SAVED_TREE (current_function_decl
), &data
);
1615 while (data
.repeat
);
1619 struct tree_opt_pass pass_remove_useless_stmts
=
1621 "useless", /* name */
1623 remove_useless_stmts
, /* execute */
1626 0, /* static_pass_number */
1628 PROP_gimple_any
, /* properties_required */
1629 0, /* properties_provided */
1630 0, /* properties_destroyed */
1631 0, /* todo_flags_start */
1632 TODO_dump_func
/* todo_flags_finish */
1636 /* Remove obviously useless statements in basic block BB. */
1639 cfg_remove_useless_stmts_bb (basic_block bb
)
1641 block_stmt_iterator bsi
;
1642 tree stmt
= NULL_TREE
;
1643 tree cond
, var
= NULL_TREE
, val
= NULL_TREE
;
1644 struct var_ann_d
*ann
;
1646 /* Check whether we come here from a condition, and if so, get the
1649 || bb
->pred
->pred_next
1650 || !(bb
->pred
->flags
& (EDGE_TRUE_VALUE
| EDGE_FALSE_VALUE
)))
1653 cond
= COND_EXPR_COND (last_stmt (bb
->pred
->src
));
1655 if (TREE_CODE (cond
) == VAR_DECL
|| TREE_CODE (cond
) == PARM_DECL
)
1658 val
= (bb
->pred
->flags
& EDGE_FALSE_VALUE
1659 ? boolean_false_node
: boolean_true_node
);
1661 else if (TREE_CODE (cond
) == TRUTH_NOT_EXPR
1662 && (TREE_CODE (TREE_OPERAND (cond
, 0)) == VAR_DECL
1663 || TREE_CODE (TREE_OPERAND (cond
, 0)) == PARM_DECL
))
1665 var
= TREE_OPERAND (cond
, 0);
1666 val
= (bb
->pred
->flags
& EDGE_FALSE_VALUE
1667 ? boolean_true_node
: boolean_false_node
);
1671 if (bb
->pred
->flags
& EDGE_FALSE_VALUE
)
1672 cond
= invert_truthvalue (cond
);
1673 if (TREE_CODE (cond
) == EQ_EXPR
1674 && (TREE_CODE (TREE_OPERAND (cond
, 0)) == VAR_DECL
1675 || TREE_CODE (TREE_OPERAND (cond
, 0)) == PARM_DECL
)
1676 && (TREE_CODE (TREE_OPERAND (cond
, 1)) == VAR_DECL
1677 || TREE_CODE (TREE_OPERAND (cond
, 1)) == PARM_DECL
1678 || TREE_CONSTANT (TREE_OPERAND (cond
, 1))))
1680 var
= TREE_OPERAND (cond
, 0);
1681 val
= TREE_OPERAND (cond
, 1);
1687 /* Only work for normal local variables. */
1688 ann
= var_ann (var
);
1691 || TREE_ADDRESSABLE (var
))
1694 if (! TREE_CONSTANT (val
))
1696 ann
= var_ann (val
);
1699 || TREE_ADDRESSABLE (val
))
1703 /* Ignore floating point variables, since comparison behaves weird for
1705 if (FLOAT_TYPE_P (TREE_TYPE (var
)))
1708 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
);)
1710 stmt
= bsi_stmt (bsi
);
1712 /* If the THEN/ELSE clause merely assigns a value to a variable/parameter
1713 which is already known to contain that value, then remove the useless
1714 THEN/ELSE clause. */
1715 if (TREE_CODE (stmt
) == MODIFY_EXPR
1716 && TREE_OPERAND (stmt
, 0) == var
1717 && operand_equal_p (val
, TREE_OPERAND (stmt
, 1), 0))
1723 /* Invalidate the var if we encounter something that could modify it. */
1724 if (TREE_CODE (stmt
) == ASM_EXPR
1725 || TREE_CODE (stmt
) == VA_ARG_EXPR
1726 || (TREE_CODE (stmt
) == MODIFY_EXPR
1727 && (TREE_OPERAND (stmt
, 0) == var
1728 || TREE_OPERAND (stmt
, 0) == val
1729 || TREE_CODE (TREE_OPERAND (stmt
, 1)) == VA_ARG_EXPR
)))
1737 /* A CFG-aware version of remove_useless_stmts. */
1740 cfg_remove_useless_stmts (void)
1744 #ifdef ENABLE_CHECKING
1745 verify_flow_info ();
1750 cfg_remove_useless_stmts_bb (bb
);
1755 /* Remove PHI nodes associated with basic block BB and all edges out of BB. */
1758 remove_phi_nodes_and_edges_for_unreachable_block (basic_block bb
)
1762 /* Since this block is no longer reachable, we can just delete all
1763 of its PHI nodes. */
1764 phi
= phi_nodes (bb
);
1767 tree next
= PHI_CHAIN (phi
);
1768 remove_phi_node (phi
, NULL_TREE
, bb
);
1772 /* Remove edges to BB's successors. */
1773 while (bb
->succ
!= NULL
)
1774 ssa_remove_edge (bb
->succ
);
1778 /* Remove statements of basic block BB. */
1781 remove_bb (basic_block bb
)
1783 block_stmt_iterator i
;
1784 source_locus loc
= 0;
1788 fprintf (dump_file
, "Removing basic block %d\n", bb
->index
);
1789 if (dump_flags
& TDF_DETAILS
)
1791 dump_bb (bb
, dump_file
, 0);
1792 fprintf (dump_file
, "\n");
1796 /* Remove all the instructions in the block. */
1797 for (i
= bsi_start (bb
); !bsi_end_p (i
); bsi_remove (&i
))
1799 tree stmt
= bsi_stmt (i
);
1801 set_bb_for_stmt (stmt
, NULL
);
1803 /* Don't warn for removed gotos. Gotos are often removed due to
1804 jump threading, thus resulting in bogus warnings. Not great,
1805 since this way we lose warnings for gotos in the original
1806 program that are indeed unreachable. */
1807 if (TREE_CODE (stmt
) != GOTO_EXPR
&& EXPR_HAS_LOCATION (stmt
) && !loc
)
1808 #ifdef USE_MAPPED_LOCATION
1809 loc
= EXPR_LOCATION (stmt
);
1811 loc
= EXPR_LOCUS (stmt
);
1815 /* If requested, give a warning that the first statement in the
1816 block is unreachable. We walk statements backwards in the
1817 loop above, so the last statement we process is the first statement
1819 if (warn_notreached
&& loc
)
1820 #ifdef USE_MAPPED_LOCATION
1821 warning ("%Hwill never be executed", &loc
);
1823 warning ("%Hwill never be executed", loc
);
1826 remove_phi_nodes_and_edges_for_unreachable_block (bb
);
1830 /* Examine BB to determine if it is a forwarding block (a block which only
1831 transfers control to a new destination). If BB is a forwarding block,
1832 then return the edge leading to the ultimate destination. */
1835 tree_block_forwards_to (basic_block bb
)
1837 block_stmt_iterator bsi
;
1838 bb_ann_t ann
= bb_ann (bb
);
1841 /* If this block is not forwardable, then avoid useless work. */
1842 if (! ann
->forwardable
)
1845 /* Set this block to not be forwardable. This prevents infinite loops since
1846 any block currently under examination is considered non-forwardable. */
1847 ann
->forwardable
= 0;
1849 /* No forwarding is possible if this block is a special block (ENTRY/EXIT),
1850 this block has more than one successor, this block's single successor is
1851 reached via an abnormal edge, this block has phi nodes, or this block's
1852 single successor has phi nodes. */
1853 if (bb
== EXIT_BLOCK_PTR
1854 || bb
== ENTRY_BLOCK_PTR
1856 || bb
->succ
->succ_next
1857 || bb
->succ
->dest
== EXIT_BLOCK_PTR
1858 || (bb
->succ
->flags
& EDGE_ABNORMAL
) != 0
1860 || phi_nodes (bb
->succ
->dest
))
1863 /* Walk past any labels at the start of this block. */
1864 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
1866 stmt
= bsi_stmt (bsi
);
1867 if (TREE_CODE (stmt
) != LABEL_EXPR
)
1871 /* If we reached the end of this block we may be able to optimize this
1873 if (bsi_end_p (bsi
))
1877 /* Recursive call to pick up chains of forwarding blocks. */
1878 dest
= tree_block_forwards_to (bb
->succ
->dest
);
1880 /* If none found, we forward to bb->succ at minimum. */
1884 ann
->forwardable
= 1;
1888 /* No forwarding possible. */
1893 /* Try to remove superfluous control structures. */
1896 cleanup_control_flow (void)
1899 block_stmt_iterator bsi
;
1900 bool retval
= false;
1905 bsi
= bsi_last (bb
);
1907 if (bsi_end_p (bsi
))
1910 stmt
= bsi_stmt (bsi
);
1911 if (TREE_CODE (stmt
) == COND_EXPR
1912 || TREE_CODE (stmt
) == SWITCH_EXPR
)
1913 retval
|= cleanup_control_expr_graph (bb
, bsi
);
1919 /* Disconnect an unreachable block in the control expression starting
1923 cleanup_control_expr_graph (basic_block bb
, block_stmt_iterator bsi
)
1926 bool retval
= false;
1927 tree expr
= bsi_stmt (bsi
), val
;
1929 if (bb
->succ
->succ_next
)
1933 switch (TREE_CODE (expr
))
1936 val
= COND_EXPR_COND (expr
);
1940 val
= SWITCH_COND (expr
);
1941 if (TREE_CODE (val
) != INTEGER_CST
)
1949 taken_edge
= find_taken_edge (bb
, val
);
1953 /* Remove all the edges except the one that is always executed. */
1954 for (e
= bb
->succ
; e
; e
= next
)
1956 next
= e
->succ_next
;
1957 if (e
!= taken_edge
)
1959 taken_edge
->probability
+= e
->probability
;
1960 taken_edge
->count
+= e
->count
;
1961 ssa_remove_edge (e
);
1965 if (taken_edge
->probability
> REG_BR_PROB_BASE
)
1966 taken_edge
->probability
= REG_BR_PROB_BASE
;
1969 taken_edge
= bb
->succ
;
1972 taken_edge
->flags
= EDGE_FALLTHRU
;
1974 /* We removed some paths from the cfg. */
1975 if (dom_computed
[CDI_DOMINATORS
] >= DOM_CONS_OK
)
1976 dom_computed
[CDI_DOMINATORS
] = DOM_CONS_OK
;
1982 /* Given a control block BB and a constant value VAL, return the edge that
1983 will be taken out of the block. If VAL does not match a unique edge,
1984 NULL is returned. */
1987 find_taken_edge (basic_block bb
, tree val
)
1991 stmt
= last_stmt (bb
);
1993 #if defined ENABLE_CHECKING
1994 if (stmt
== NULL_TREE
|| !is_ctrl_stmt (stmt
))
1998 /* If VAL is not a constant, we can't determine which edge might
2000 if (val
== NULL
|| !really_constant_p (val
))
2003 if (TREE_CODE (stmt
) == COND_EXPR
)
2004 return find_taken_edge_cond_expr (bb
, val
);
2006 if (TREE_CODE (stmt
) == SWITCH_EXPR
)
2007 return find_taken_edge_switch_expr (bb
, val
);
2013 /* Given a constant value VAL and the entry block BB to a COND_EXPR
2014 statement, determine which of the two edges will be taken out of the
2015 block. Return NULL if either edge may be taken. */
2018 find_taken_edge_cond_expr (basic_block bb
, tree val
)
2020 edge true_edge
, false_edge
;
2022 extract_true_false_edges_from_block (bb
, &true_edge
, &false_edge
);
2024 /* If both edges of the branch lead to the same basic block, it doesn't
2025 matter which edge is taken. */
2026 if (true_edge
->dest
== false_edge
->dest
)
2029 /* Otherwise, try to determine which branch of the if() will be taken.
2030 If VAL is a constant but it can't be reduced to a 0 or a 1, then
2031 we don't really know which edge will be taken at runtime. This
2032 may happen when comparing addresses (e.g., if (&var1 == 4)). */
2033 if (integer_nonzerop (val
))
2035 else if (integer_zerop (val
))
2042 /* Given a constant value VAL and the entry block BB to a SWITCH_EXPR
2043 statement, determine which edge will be taken out of the block. Return
2044 NULL if any edge may be taken. */
2047 find_taken_edge_switch_expr (basic_block bb
, tree val
)
2049 tree switch_expr
, taken_case
;
2050 basic_block dest_bb
;
2053 if (TREE_CODE (val
) != INTEGER_CST
)
2056 switch_expr
= last_stmt (bb
);
2057 taken_case
= find_case_label_for_value (switch_expr
, val
);
2058 dest_bb
= label_to_block (CASE_LABEL (taken_case
));
2060 e
= find_edge (bb
, dest_bb
);
2067 /* Return the CASE_LABEL_EXPR that SWITCH_EXPR will take for VAL.
2068 We can make optimal use here of the fact that the case labels are
2069 sorted: We can do a binary search for a case matching VAL. */
2072 find_case_label_for_value (tree switch_expr
, tree val
)
2074 tree vec
= SWITCH_LABELS (switch_expr
);
2075 size_t low
, high
, n
= TREE_VEC_LENGTH (vec
);
2076 tree default_case
= TREE_VEC_ELT (vec
, n
- 1);
2078 for (low
= -1, high
= n
- 1; high
- low
> 1; )
2080 size_t i
= (high
+ low
) / 2;
2081 tree t
= TREE_VEC_ELT (vec
, i
);
2084 /* Cache the result of comparing CASE_LOW and val. */
2085 cmp
= tree_int_cst_compare (CASE_LOW (t
), val
);
2092 if (CASE_HIGH (t
) == NULL
)
2094 /* A singe-valued case label. */
2100 /* A case range. We can only handle integer ranges. */
2101 if (cmp
<= 0 && tree_int_cst_compare (CASE_HIGH (t
), val
) >= 0)
2106 return default_case
;
2110 /* If all the PHI nodes in DEST have alternatives for E1 and E2 and
2111 those alternatives are equal in each of the PHI nodes, then return
2112 true, else return false. */
2115 phi_alternatives_equal (basic_block dest
, edge e1
, edge e2
)
2117 tree phi
, val1
, val2
;
2120 for (phi
= phi_nodes (dest
); phi
; phi
= PHI_CHAIN (phi
))
2122 n1
= phi_arg_from_edge (phi
, e1
);
2123 n2
= phi_arg_from_edge (phi
, e2
);
2125 #ifdef ENABLE_CHECKING
2126 if (n1
< 0 || n2
< 0)
2130 val1
= PHI_ARG_DEF (phi
, n1
);
2131 val2
= PHI_ARG_DEF (phi
, n2
);
2133 if (!operand_equal_p (val1
, val2
, 0))
2141 /* Computing the Dominance Frontier:
2143 As described in Morgan, section 3.5, this may be done simply by
2144 walking the dominator tree bottom-up, computing the frontier for
2145 the children before the parent. When considering a block B,
2146 there are two cases:
2148 (1) A flow graph edge leaving B that does not lead to a child
2149 of B in the dominator tree must be a block that is either equal
2150 to B or not dominated by B. Such blocks belong in the frontier
2153 (2) Consider a block X in the frontier of one of the children C
2154 of B. If X is not equal to B and is not dominated by B, it
2155 is in the frontier of B. */
2158 compute_dominance_frontiers_1 (bitmap
*frontiers
, basic_block bb
, sbitmap done
)
2163 SET_BIT (done
, bb
->index
);
2165 /* Do the frontier of the children first. Not all children in the
2166 dominator tree (blocks dominated by this one) are children in the
2167 CFG, so check all blocks. */
2168 for (c
= first_dom_son (CDI_DOMINATORS
, bb
);
2170 c
= next_dom_son (CDI_DOMINATORS
, c
))
2172 if (! TEST_BIT (done
, c
->index
))
2173 compute_dominance_frontiers_1 (frontiers
, c
, done
);
2176 /* Find blocks conforming to rule (1) above. */
2177 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
2179 if (e
->dest
== EXIT_BLOCK_PTR
)
2181 if (get_immediate_dominator (CDI_DOMINATORS
, e
->dest
) != bb
)
2182 bitmap_set_bit (frontiers
[bb
->index
], e
->dest
->index
);
2185 /* Find blocks conforming to rule (2). */
2186 for (c
= first_dom_son (CDI_DOMINATORS
, bb
);
2188 c
= next_dom_son (CDI_DOMINATORS
, c
))
2192 EXECUTE_IF_SET_IN_BITMAP (frontiers
[c
->index
], 0, x
,
2194 if (get_immediate_dominator (CDI_DOMINATORS
, BASIC_BLOCK (x
)) != bb
)
2195 bitmap_set_bit (frontiers
[bb
->index
], x
);
2202 compute_dominance_frontiers (bitmap
*frontiers
)
2204 sbitmap done
= sbitmap_alloc (last_basic_block
);
2206 timevar_push (TV_DOM_FRONTIERS
);
2208 sbitmap_zero (done
);
2210 compute_dominance_frontiers_1 (frontiers
, ENTRY_BLOCK_PTR
->succ
->dest
, done
);
2212 sbitmap_free (done
);
2214 timevar_pop (TV_DOM_FRONTIERS
);
2219 /*---------------------------------------------------------------------------
2221 ---------------------------------------------------------------------------*/
2223 /* Dump tree-specific information of block BB to file OUTF. */
2226 tree_dump_bb (basic_block bb
, FILE *outf
, int indent
)
2228 dump_generic_bb (outf
, bb
, indent
, TDF_VOPS
);
2232 /* Dump a basic block on stderr. */
2235 debug_tree_bb (basic_block bb
)
2237 dump_bb (bb
, stderr
, 0);
2241 /* Dump basic block with index N on stderr. */
2244 debug_tree_bb_n (int n
)
2246 debug_tree_bb (BASIC_BLOCK (n
));
2247 return BASIC_BLOCK (n
);
2251 /* Dump the CFG on stderr.
2253 FLAGS are the same used by the tree dumping functions
2254 (see TDF_* in tree.h). */
2257 debug_tree_cfg (int flags
)
2259 dump_tree_cfg (stderr
, flags
);
2263 /* Dump the program showing basic block boundaries on the given FILE.
2265 FLAGS are the same used by the tree dumping functions (see TDF_* in
2269 dump_tree_cfg (FILE *file
, int flags
)
2271 if (flags
& TDF_DETAILS
)
2273 const char *funcname
2274 = lang_hooks
.decl_printable_name (current_function_decl
, 2);
2277 fprintf (file
, ";; Function %s\n\n", funcname
);
2278 fprintf (file
, ";; \n%d basic blocks, %d edges, last basic block %d.\n\n",
2279 n_basic_blocks
, n_edges
, last_basic_block
);
2281 brief_dump_cfg (file
);
2282 fprintf (file
, "\n");
2285 if (flags
& TDF_STATS
)
2286 dump_cfg_stats (file
);
2288 dump_function_to_file (current_function_decl
, file
, flags
| TDF_BLOCKS
);
2292 /* Dump CFG statistics on FILE. */
2295 dump_cfg_stats (FILE *file
)
2297 static long max_num_merged_labels
= 0;
2298 unsigned long size
, total
= 0;
2301 const char * const fmt_str
= "%-30s%-13s%12s\n";
2302 const char * const fmt_str_1
= "%-30s%13lu%11lu%c\n";
2303 const char * const fmt_str_3
= "%-43s%11lu%c\n";
2304 const char *funcname
2305 = lang_hooks
.decl_printable_name (current_function_decl
, 2);
2308 fprintf (file
, "\nCFG Statistics for %s\n\n", funcname
);
2310 fprintf (file
, "---------------------------------------------------------\n");
2311 fprintf (file
, fmt_str
, "", " Number of ", "Memory");
2312 fprintf (file
, fmt_str
, "", " instances ", "used ");
2313 fprintf (file
, "---------------------------------------------------------\n");
2315 size
= n_basic_blocks
* sizeof (struct basic_block_def
);
2317 fprintf (file
, fmt_str_1
, "Basic blocks", n_basic_blocks
, SCALE (size
),
2324 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
2327 size
= n_edges
* sizeof (struct edge_def
);
2329 fprintf (file
, fmt_str_1
, "Edges", n_edges
, SCALE (size
), LABEL (size
));
2331 size
= n_basic_blocks
* sizeof (struct bb_ann_d
);
2333 fprintf (file
, fmt_str_1
, "Basic block annotations", n_basic_blocks
,
2334 SCALE (size
), LABEL (size
));
2336 fprintf (file
, "---------------------------------------------------------\n");
2337 fprintf (file
, fmt_str_3
, "Total memory used by CFG data", SCALE (total
),
2339 fprintf (file
, "---------------------------------------------------------\n");
2340 fprintf (file
, "\n");
2342 if (cfg_stats
.num_merged_labels
> max_num_merged_labels
)
2343 max_num_merged_labels
= cfg_stats
.num_merged_labels
;
2345 fprintf (file
, "Coalesced label blocks: %ld (Max so far: %ld)\n",
2346 cfg_stats
.num_merged_labels
, max_num_merged_labels
);
2348 fprintf (file
, "\n");
2352 /* Dump CFG statistics on stderr. Keep extern so that it's always
2353 linked in the final executable. */
2356 debug_cfg_stats (void)
2358 dump_cfg_stats (stderr
);
2362 /* Dump the flowgraph to a .vcg FILE. */
2365 tree_cfg2vcg (FILE *file
)
2369 const char *funcname
2370 = lang_hooks
.decl_printable_name (current_function_decl
, 2);
2372 /* Write the file header. */
2373 fprintf (file
, "graph: { title: \"%s\"\n", funcname
);
2374 fprintf (file
, "node: { title: \"ENTRY\" label: \"ENTRY\" }\n");
2375 fprintf (file
, "node: { title: \"EXIT\" label: \"EXIT\" }\n");
2377 /* Write blocks and edges. */
2378 for (e
= ENTRY_BLOCK_PTR
->succ
; e
; e
= e
->succ_next
)
2380 fprintf (file
, "edge: { sourcename: \"ENTRY\" targetname: \"%d\"",
2383 if (e
->flags
& EDGE_FAKE
)
2384 fprintf (file
, " linestyle: dotted priority: 10");
2386 fprintf (file
, " linestyle: solid priority: 100");
2388 fprintf (file
, " }\n");
2394 enum tree_code head_code
, end_code
;
2395 const char *head_name
, *end_name
;
2398 tree first
= first_stmt (bb
);
2399 tree last
= last_stmt (bb
);
2403 head_code
= TREE_CODE (first
);
2404 head_name
= tree_code_name
[head_code
];
2405 head_line
= get_lineno (first
);
2408 head_name
= "no-statement";
2412 end_code
= TREE_CODE (last
);
2413 end_name
= tree_code_name
[end_code
];
2414 end_line
= get_lineno (last
);
2417 end_name
= "no-statement";
2419 fprintf (file
, "node: { title: \"%d\" label: \"#%d\\n%s (%d)\\n%s (%d)\"}\n",
2420 bb
->index
, bb
->index
, head_name
, head_line
, end_name
,
2423 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
2425 if (e
->dest
== EXIT_BLOCK_PTR
)
2426 fprintf (file
, "edge: { sourcename: \"%d\" targetname: \"EXIT\"", bb
->index
);
2428 fprintf (file
, "edge: { sourcename: \"%d\" targetname: \"%d\"", bb
->index
, e
->dest
->index
);
2430 if (e
->flags
& EDGE_FAKE
)
2431 fprintf (file
, " priority: 10 linestyle: dotted");
2433 fprintf (file
, " priority: 100 linestyle: solid");
2435 fprintf (file
, " }\n");
2438 if (bb
->next_bb
!= EXIT_BLOCK_PTR
)
2442 fputs ("}\n\n", file
);
2447 /*---------------------------------------------------------------------------
2448 Miscellaneous helpers
2449 ---------------------------------------------------------------------------*/
2451 /* Return true if T represents a stmt that always transfers control. */
2454 is_ctrl_stmt (tree t
)
2456 return (TREE_CODE (t
) == COND_EXPR
2457 || TREE_CODE (t
) == SWITCH_EXPR
2458 || TREE_CODE (t
) == GOTO_EXPR
2459 || TREE_CODE (t
) == RETURN_EXPR
2460 || TREE_CODE (t
) == RESX_EXPR
);
2464 /* Return true if T is a statement that may alter the flow of control
2465 (e.g., a call to a non-returning function). */
2468 is_ctrl_altering_stmt (tree t
)
2472 #if defined ENABLE_CHECKING
2477 switch (TREE_CODE (t
))
2480 /* A MODIFY_EXPR with a rhs of a call has the characteristics
2482 call
= TREE_OPERAND (t
, 1);
2483 if (TREE_CODE (call
) != CALL_EXPR
)
2488 /* A non-pure/const CALL_EXPR alters flow control if the current
2489 function has nonlocal labels. */
2490 if (TREE_SIDE_EFFECTS (t
)
2491 && current_function_has_nonlocal_label
)
2494 /* A CALL_EXPR also alters control flow if it does not return. */
2495 if (call_expr_flags (call
) & (ECF_NORETURN
| ECF_LONGJMP
))
2503 /* If a statement can throw, it alters control flow. */
2504 return tree_can_throw_internal (t
);
2508 /* Return true if T is a computed goto. */
2511 computed_goto_p (tree t
)
2513 return (TREE_CODE (t
) == GOTO_EXPR
2514 && TREE_CODE (GOTO_DESTINATION (t
)) != LABEL_DECL
);
2518 /* Checks whether EXPR is a simple local goto. */
2521 simple_goto_p (tree expr
)
2523 return (TREE_CODE (expr
) == GOTO_EXPR
2524 && TREE_CODE (GOTO_DESTINATION (expr
)) == LABEL_DECL
2525 && (decl_function_context (GOTO_DESTINATION (expr
))
2526 == current_function_decl
));
2530 /* Return true if T should start a new basic block. PREV_T is the
2531 statement preceding T. It is used when T is a label or a case label.
2532 Labels should only start a new basic block if their previous statement
2533 wasn't a label. Otherwise, sequence of labels would generate
2534 unnecessary basic blocks that only contain a single label. */
2537 stmt_starts_bb_p (tree t
, tree prev_t
)
2539 enum tree_code code
;
2544 /* LABEL_EXPRs start a new basic block only if the preceding
2545 statement wasn't a label of the same type. This prevents the
2546 creation of consecutive blocks that have nothing but a single
2548 code
= TREE_CODE (t
);
2549 if (code
== LABEL_EXPR
)
2551 /* Nonlocal and computed GOTO targets always start a new block. */
2552 if (code
== LABEL_EXPR
2553 && (DECL_NONLOCAL (LABEL_EXPR_LABEL (t
))
2554 || FORCED_LABEL (LABEL_EXPR_LABEL (t
))))
2557 if (prev_t
&& TREE_CODE (prev_t
) == code
)
2559 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (prev_t
)))
2562 cfg_stats
.num_merged_labels
++;
2573 /* Return true if T should end a basic block. */
2576 stmt_ends_bb_p (tree t
)
2578 return is_ctrl_stmt (t
) || is_ctrl_altering_stmt (t
);
2582 /* Add gotos that used to be represented implicitly in the CFG. */
2585 disband_implicit_edges (void)
2588 block_stmt_iterator last
;
2594 last
= bsi_last (bb
);
2595 stmt
= last_stmt (bb
);
2597 if (stmt
&& TREE_CODE (stmt
) == COND_EXPR
)
2599 /* Remove superfluous gotos from COND_EXPR branches. Moved
2600 from cfg_remove_useless_stmts here since it violates the
2601 invariants for tree--cfg correspondence and thus fits better
2602 here where we do it anyway. */
2603 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
2605 if (e
->dest
!= bb
->next_bb
)
2608 if (e
->flags
& EDGE_TRUE_VALUE
)
2609 COND_EXPR_THEN (stmt
) = build_empty_stmt ();
2610 else if (e
->flags
& EDGE_FALSE_VALUE
)
2611 COND_EXPR_ELSE (stmt
) = build_empty_stmt ();
2614 e
->flags
|= EDGE_FALLTHRU
;
2620 if (stmt
&& TREE_CODE (stmt
) == RETURN_EXPR
)
2622 /* Remove the RETURN_EXPR if we may fall though to the exit
2625 || bb
->succ
->succ_next
2626 || bb
->succ
->dest
!= EXIT_BLOCK_PTR
)
2629 if (bb
->next_bb
== EXIT_BLOCK_PTR
2630 && !TREE_OPERAND (stmt
, 0))
2633 bb
->succ
->flags
|= EDGE_FALLTHRU
;
2638 /* There can be no fallthru edge if the last statement is a control
2640 if (stmt
&& is_ctrl_stmt (stmt
))
2643 /* Find a fallthru edge and emit the goto if necessary. */
2644 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
2645 if (e
->flags
& EDGE_FALLTHRU
)
2648 if (!e
|| e
->dest
== bb
->next_bb
)
2651 if (e
->dest
== EXIT_BLOCK_PTR
)
2654 label
= tree_block_label (e
->dest
);
2656 stmt
= build1 (GOTO_EXPR
, void_type_node
, label
);
2657 #ifdef USE_MAPPED_LOCATION
2658 SET_EXPR_LOCATION (stmt
, e
->goto_locus
);
2660 SET_EXPR_LOCUS (stmt
, e
->goto_locus
);
2662 bsi_insert_after (&last
, stmt
, BSI_NEW_STMT
);
2663 e
->flags
&= ~EDGE_FALLTHRU
;
2667 /* Remove block annotations and other datastructures. */
2670 delete_tree_cfg_annotations (void)
2673 if (n_basic_blocks
> 0)
2674 free_blocks_annotations ();
2676 label_to_block_map
= NULL
;
2683 /* Return the first statement in basic block BB. */
2686 first_stmt (basic_block bb
)
2688 block_stmt_iterator i
= bsi_start (bb
);
2689 return !bsi_end_p (i
) ? bsi_stmt (i
) : NULL_TREE
;
2693 /* Return the last statement in basic block BB. */
2696 last_stmt (basic_block bb
)
2698 block_stmt_iterator b
= bsi_last (bb
);
2699 return !bsi_end_p (b
) ? bsi_stmt (b
) : NULL_TREE
;
2703 /* Return a pointer to the last statement in block BB. */
2706 last_stmt_ptr (basic_block bb
)
2708 block_stmt_iterator last
= bsi_last (bb
);
2709 return !bsi_end_p (last
) ? bsi_stmt_ptr (last
) : NULL
;
2713 /* Return the last statement of an otherwise empty block. Return NULL
2714 if the block is totally empty, or if it contains more than one
2718 last_and_only_stmt (basic_block bb
)
2720 block_stmt_iterator i
= bsi_last (bb
);
2726 last
= bsi_stmt (i
);
2731 /* Empty statements should no longer appear in the instruction stream.
2732 Everything that might have appeared before should be deleted by
2733 remove_useless_stmts, and the optimizers should just bsi_remove
2734 instead of smashing with build_empty_stmt.
2736 Thus the only thing that should appear here in a block containing
2737 one executable statement is a label. */
2738 prev
= bsi_stmt (i
);
2739 if (TREE_CODE (prev
) == LABEL_EXPR
)
2746 /* Mark BB as the basic block holding statement T. */
2749 set_bb_for_stmt (tree t
, basic_block bb
)
2751 if (TREE_CODE (t
) == STATEMENT_LIST
)
2753 tree_stmt_iterator i
;
2754 for (i
= tsi_start (t
); !tsi_end_p (i
); tsi_next (&i
))
2755 set_bb_for_stmt (tsi_stmt (i
), bb
);
2759 stmt_ann_t ann
= get_stmt_ann (t
);
2762 /* If the statement is a label, add the label to block-to-labels map
2763 so that we can speed up edge creation for GOTO_EXPRs. */
2764 if (TREE_CODE (t
) == LABEL_EXPR
)
2768 t
= LABEL_EXPR_LABEL (t
);
2769 uid
= LABEL_DECL_UID (t
);
2772 LABEL_DECL_UID (t
) = uid
= cfun
->last_label_uid
++;
2773 if (VARRAY_SIZE (label_to_block_map
) <= (unsigned) uid
)
2774 VARRAY_GROW (label_to_block_map
, 3 * uid
/ 2);
2778 #ifdef ENABLE_CHECKING
2779 /* We're moving an existing label. Make sure that we've
2780 removed it from the old block. */
2781 if (bb
&& VARRAY_BB (label_to_block_map
, uid
))
2785 VARRAY_BB (label_to_block_map
, uid
) = bb
;
2791 /* Insert statement (or statement list) T before the statement
2792 pointed-to by iterator I. M specifies how to update iterator I
2793 after insertion (see enum bsi_iterator_update). */
2796 bsi_insert_before (block_stmt_iterator
*i
, tree t
, enum bsi_iterator_update m
)
2798 set_bb_for_stmt (t
, i
->bb
);
2800 tsi_link_before (&i
->tsi
, t
, m
);
2804 /* Insert statement (or statement list) T after the statement
2805 pointed-to by iterator I. M specifies how to update iterator I
2806 after insertion (see enum bsi_iterator_update). */
2809 bsi_insert_after (block_stmt_iterator
*i
, tree t
, enum bsi_iterator_update m
)
2811 set_bb_for_stmt (t
, i
->bb
);
2813 tsi_link_after (&i
->tsi
, t
, m
);
2817 /* Remove the statement pointed to by iterator I. The iterator is updated
2818 to the next statement. */
2821 bsi_remove (block_stmt_iterator
*i
)
2823 tree t
= bsi_stmt (*i
);
2824 set_bb_for_stmt (t
, NULL
);
2826 tsi_delink (&i
->tsi
);
2830 /* Move the statement at FROM so it comes right after the statement at TO. */
2833 bsi_move_after (block_stmt_iterator
*from
, block_stmt_iterator
*to
)
2835 tree stmt
= bsi_stmt (*from
);
2837 bsi_insert_after (to
, stmt
, BSI_SAME_STMT
);
2841 /* Move the statement at FROM so it comes right before the statement at TO. */
2844 bsi_move_before (block_stmt_iterator
*from
, block_stmt_iterator
*to
)
2846 tree stmt
= bsi_stmt (*from
);
2848 bsi_insert_before (to
, stmt
, BSI_SAME_STMT
);
2852 /* Move the statement at FROM to the end of basic block BB. */
2855 bsi_move_to_bb_end (block_stmt_iterator
*from
, basic_block bb
)
2857 block_stmt_iterator last
= bsi_last (bb
);
2859 /* Have to check bsi_end_p because it could be an empty block. */
2860 if (!bsi_end_p (last
) && is_ctrl_stmt (bsi_stmt (last
)))
2861 bsi_move_before (from
, &last
);
2863 bsi_move_after (from
, &last
);
2867 /* Replace the contents of the statement pointed to by iterator BSI
2868 with STMT. If PRESERVE_EH_INFO is true, the exception handling
2869 information of the original statement is preserved. */
2872 bsi_replace (const block_stmt_iterator
*bsi
, tree stmt
, bool preserve_eh_info
)
2875 tree orig_stmt
= bsi_stmt (*bsi
);
2877 SET_EXPR_LOCUS (stmt
, EXPR_LOCUS (orig_stmt
));
2878 set_bb_for_stmt (stmt
, bsi
->bb
);
2880 /* Preserve EH region information from the original statement, if
2881 requested by the caller. */
2882 if (preserve_eh_info
)
2884 eh_region
= lookup_stmt_eh_region (orig_stmt
);
2886 add_stmt_to_eh_region (stmt
, eh_region
);
2889 *bsi_stmt_ptr (*bsi
) = stmt
;
2894 /* Insert the statement pointed-to by BSI into edge E. Every attempt
2895 is made to place the statement in an existing basic block, but
2896 sometimes that isn't possible. When it isn't possible, the edge is
2897 split and the statement is added to the new block.
2899 In all cases, the returned *BSI points to the correct location. The
2900 return value is true if insertion should be done after the location,
2901 or false if it should be done before the location. */
2904 tree_find_edge_insert_loc (edge e
, block_stmt_iterator
*bsi
)
2906 basic_block dest
, src
;
2912 /* If the destination has one predecessor which has no PHI nodes,
2913 insert there. Except for the exit block.
2915 The requirement for no PHI nodes could be relaxed. Basically we
2916 would have to examine the PHIs to prove that none of them used
2917 the value set by the statement we want to insert on E. That
2918 hardly seems worth the effort. */
2919 if (dest
->pred
->pred_next
== NULL
2920 && ! phi_nodes (dest
)
2921 && dest
!= EXIT_BLOCK_PTR
)
2923 *bsi
= bsi_start (dest
);
2924 if (bsi_end_p (*bsi
))
2927 /* Make sure we insert after any leading labels. */
2928 tmp
= bsi_stmt (*bsi
);
2929 while (TREE_CODE (tmp
) == LABEL_EXPR
)
2932 if (bsi_end_p (*bsi
))
2934 tmp
= bsi_stmt (*bsi
);
2937 if (bsi_end_p (*bsi
))
2939 *bsi
= bsi_last (dest
);
2946 /* If the source has one successor, the edge is not abnormal and
2947 the last statement does not end a basic block, insert there.
2948 Except for the entry block. */
2950 if ((e
->flags
& EDGE_ABNORMAL
) == 0
2951 && src
->succ
->succ_next
== NULL
2952 && src
!= ENTRY_BLOCK_PTR
)
2954 *bsi
= bsi_last (src
);
2955 if (bsi_end_p (*bsi
))
2958 tmp
= bsi_stmt (*bsi
);
2959 if (!stmt_ends_bb_p (tmp
))
2962 /* Insert code just before returning the value. We may need to decompose
2963 the return in the case it contains non-trivial operand. */
2964 if (TREE_CODE (tmp
) == RETURN_EXPR
)
2966 tree op
= TREE_OPERAND (tmp
, 0);
2967 if (!is_gimple_val (op
))
2969 if (TREE_CODE (op
) != MODIFY_EXPR
)
2971 bsi_insert_before (bsi
, op
, BSI_NEW_STMT
);
2972 TREE_OPERAND (tmp
, 0) = TREE_OPERAND (op
, 0);
2979 /* Otherwise, create a new basic block, and split this edge. */
2980 dest
= split_edge (e
);
2986 /* This routine will commit all pending edge insertions, creating any new
2987 basic blocks which are necessary.
2989 If specified, NEW_BLOCKS returns a count of the number of new basic
2990 blocks which were created. */
2993 bsi_commit_edge_inserts (int *new_blocks
)
2999 blocks
= n_basic_blocks
;
3001 bsi_commit_edge_inserts_1 (ENTRY_BLOCK_PTR
->succ
);
3004 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
3005 bsi_commit_edge_inserts_1 (e
);
3008 *new_blocks
= n_basic_blocks
- blocks
;
3012 /* Commit insertions pending at edge E. */
3015 bsi_commit_edge_inserts_1 (edge e
)
3017 if (PENDING_STMT (e
))
3019 block_stmt_iterator bsi
;
3020 tree stmt
= PENDING_STMT (e
);
3022 PENDING_STMT (e
) = NULL_TREE
;
3024 if (tree_find_edge_insert_loc (e
, &bsi
))
3025 bsi_insert_after (&bsi
, stmt
, BSI_NEW_STMT
);
3027 bsi_insert_before (&bsi
, stmt
, BSI_NEW_STMT
);
3032 /* Add STMT to the pending list of edge E. No actual insertion is
3033 made until a call to bsi_commit_edge_inserts () is made. */
3036 bsi_insert_on_edge (edge e
, tree stmt
)
3038 append_to_statement_list (stmt
, &PENDING_STMT (e
));
3042 /* Specialized edge insertion for SSA-PRE. FIXME: This should
3043 probably disappear. The only reason it's here is because PRE needs
3044 the call to tree_find_edge_insert_loc(). */
3046 void pre_insert_on_edge (edge e
, tree stmt
);
3049 pre_insert_on_edge (edge e
, tree stmt
)
3051 block_stmt_iterator bsi
;
3053 if (PENDING_STMT (e
))
3056 if (tree_find_edge_insert_loc (e
, &bsi
))
3057 bsi_insert_after (&bsi
, stmt
, BSI_NEW_STMT
);
3059 bsi_insert_before (&bsi
, stmt
, BSI_NEW_STMT
);
3063 /*---------------------------------------------------------------------------
3064 Tree specific functions for CFG manipulation
3065 ---------------------------------------------------------------------------*/
3067 /* Split a (typically critical) edge EDGE_IN. Return the new block.
3068 Abort on abnormal edges. */
3071 tree_split_edge (edge edge_in
)
3073 basic_block new_bb
, after_bb
, dest
, src
;
3078 /* Abnormal edges cannot be split. */
3079 if (edge_in
->flags
& EDGE_ABNORMAL
)
3083 dest
= edge_in
->dest
;
3085 /* Place the new block in the block list. Try to keep the new block
3086 near its "logical" location. This is of most help to humans looking
3087 at debugging dumps. */
3088 for (e
= dest
->pred
; e
; e
= e
->pred_next
)
3089 if (e
->src
->next_bb
== dest
)
3092 after_bb
= dest
->prev_bb
;
3094 after_bb
= edge_in
->src
;
3096 new_bb
= create_empty_bb (after_bb
);
3097 new_edge
= make_edge (new_bb
, dest
, EDGE_FALLTHRU
);
3099 /* Find all the PHI arguments on the original edge, and change them to
3100 the new edge. Do it before redirection, so that the argument does not
3102 for (phi
= phi_nodes (dest
); phi
; phi
= PHI_CHAIN (phi
))
3104 num_elem
= PHI_NUM_ARGS (phi
);
3105 for (i
= 0; i
< num_elem
; i
++)
3106 if (PHI_ARG_EDGE (phi
, i
) == edge_in
)
3108 PHI_ARG_EDGE (phi
, i
) = new_edge
;
3113 if (!redirect_edge_and_branch (edge_in
, new_bb
))
3116 if (PENDING_STMT (edge_in
))
3123 /* Return true when BB has label LABEL in it. */
3126 has_label_p (basic_block bb
, tree label
)
3128 block_stmt_iterator bsi
;
3130 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
3132 tree stmt
= bsi_stmt (bsi
);
3134 if (TREE_CODE (stmt
) != LABEL_EXPR
)
3136 if (LABEL_EXPR_LABEL (stmt
) == label
)
3143 /* Callback for walk_tree, check that all elements with address taken are
3144 properly noticed as such. */
3147 verify_expr (tree
*tp
, int *walk_subtrees
, void *data ATTRIBUTE_UNUSED
)
3154 /* Check operand N for being valid GIMPLE and give error MSG if not. */
3155 #define CHECK_OP(N, MSG) \
3156 do { if (TREE_CODE_CLASS (TREE_CODE (TREE_OPERAND (t, N))) != 'c' \
3157 && !is_gimple_val (TREE_OPERAND (t, N))) \
3158 { error (MSG); return TREE_OPERAND (t, N); }} while (0)
3160 switch (TREE_CODE (t
))
3163 if (SSA_NAME_IN_FREE_LIST (t
))
3165 error ("SSA name in freelist but still referenced");
3171 x
= TREE_OPERAND (t
, 0);
3172 if (TREE_CODE (x
) == BIT_FIELD_REF
3173 && is_gimple_reg (TREE_OPERAND (x
, 0)))
3175 error ("GIMPLE register modified with BIT_FIELD_REF");
3181 /* Skip any references (they will be checked when we recurse down the
3182 tree) and ensure that any variable used as a prefix is marked
3184 for (x
= TREE_OPERAND (t
, 0);
3185 (handled_component_p (x
)
3186 || TREE_CODE (x
) == REALPART_EXPR
3187 || TREE_CODE (x
) == IMAGPART_EXPR
);
3188 x
= TREE_OPERAND (x
, 0))
3191 if (TREE_CODE (x
) != VAR_DECL
&& TREE_CODE (x
) != PARM_DECL
)
3193 if (!TREE_ADDRESSABLE (x
))
3195 error ("address taken, but ADDRESSABLE bit not set");
3201 x
= TREE_OPERAND (t
, 0);
3202 if (TREE_CODE (TREE_TYPE (x
)) != BOOLEAN_TYPE
)
3204 error ("non-boolean used in condition");
3211 case FIX_TRUNC_EXPR
:
3213 case FIX_FLOOR_EXPR
:
3214 case FIX_ROUND_EXPR
:
3219 case NON_LVALUE_EXPR
:
3220 case TRUTH_NOT_EXPR
:
3221 CHECK_OP (0, "Invalid operand to unary operator");
3228 case ARRAY_RANGE_REF
:
3230 case VIEW_CONVERT_EXPR
:
3231 /* We have a nest of references. Verify that each of the operands
3232 that determine where to reference is either a constant or a variable,
3233 verify that the base is valid, and then show we've already checked
3235 while (TREE_CODE (t
) == REALPART_EXPR
|| TREE_CODE (t
) == IMAGPART_EXPR
3236 || handled_component_p (t
))
3238 if (TREE_CODE (t
) == COMPONENT_REF
&& TREE_OPERAND (t
, 2))
3239 CHECK_OP (2, "Invalid COMPONENT_REF offset operator");
3240 else if (TREE_CODE (t
) == ARRAY_REF
3241 || TREE_CODE (t
) == ARRAY_RANGE_REF
)
3243 CHECK_OP (1, "Invalid array index.");
3244 if (TREE_OPERAND (t
, 2))
3245 CHECK_OP (2, "Invalid array lower bound.");
3246 if (TREE_OPERAND (t
, 3))
3247 CHECK_OP (3, "Invalid array stride.");
3249 else if (TREE_CODE (t
) == BIT_FIELD_REF
)
3251 CHECK_OP (1, "Invalid operand to BIT_FIELD_REF");
3252 CHECK_OP (2, "Invalid operand to BIT_FIELD_REF");
3255 t
= TREE_OPERAND (t
, 0);
3258 if (TREE_CODE_CLASS (TREE_CODE (t
)) != 'c'
3259 && !is_gimple_lvalue (t
))
3261 error ("Invalid reference prefix.");
3273 case UNORDERED_EXPR
:
3284 case TRUNC_DIV_EXPR
:
3286 case FLOOR_DIV_EXPR
:
3287 case ROUND_DIV_EXPR
:
3288 case TRUNC_MOD_EXPR
:
3290 case FLOOR_MOD_EXPR
:
3291 case ROUND_MOD_EXPR
:
3293 case EXACT_DIV_EXPR
:
3303 x
= TREE_OPERAND (t
, 0);
3304 /* We check for constants explicitly since they are not considered
3305 gimple invariants if they overflowed. */
3306 if (TREE_CODE_CLASS (TREE_CODE (x
)) != 'c'
3307 && !is_gimple_val (x
))
3309 error ("Invalid operand to binary operator");
3312 x
= TREE_OPERAND (t
, 1);
3313 /* We check for constants explicitly since they are not considered
3314 gimple invariants if they overflowed. */
3315 if (TREE_CODE_CLASS (TREE_CODE (x
)) != 'c'
3316 && !is_gimple_val (x
))
3318 error ("Invalid operand to binary operator");
3332 /* Verify STMT, return true if STMT is not in GIMPLE form.
3333 TODO: Implement type checking. */
3336 verify_stmt (tree stmt
, bool last_in_block
)
3340 if (!is_gimple_stmt (stmt
))
3342 error ("Is not a valid GIMPLE statement.");
3346 addr
= walk_tree (&stmt
, verify_expr
, NULL
, NULL
);
3349 debug_generic_stmt (addr
);
3353 /* If the statement is marked as part of an EH region, then it is
3354 expected that the statement could throw. Verify that when we
3355 have optimizations that simplify statements such that we prove
3356 that they cannot throw, that we update other data structures
3358 if (lookup_stmt_eh_region (stmt
) >= 0)
3360 if (!tree_could_throw_p (stmt
))
3362 error ("Statement marked for throw, but doesn't.");
3365 if (!last_in_block
&& tree_can_throw_internal (stmt
))
3367 error ("Statement marked for throw in middle of block.");
3375 debug_generic_stmt (stmt
);
3380 /* Return true when the T can be shared. */
3383 tree_node_can_be_shared (tree t
)
3385 if (TYPE_P (t
) || DECL_P (t
)
3386 /* We check for constants explicitly since they are not considered
3387 gimple invariants if they overflowed. */
3388 || TREE_CODE_CLASS (TREE_CODE (t
)) == 'c'
3389 || is_gimple_min_invariant (t
)
3390 || TREE_CODE (t
) == SSA_NAME
)
3393 while (((TREE_CODE (t
) == ARRAY_REF
|| TREE_CODE (t
) == ARRAY_RANGE_REF
)
3394 /* We check for constants explicitly since they are not considered
3395 gimple invariants if they overflowed. */
3396 && (TREE_CODE_CLASS (TREE_CODE (TREE_OPERAND (t
, 1))) == 'c'
3397 || is_gimple_min_invariant (TREE_OPERAND (t
, 1))))
3398 || (TREE_CODE (t
) == COMPONENT_REF
3399 || TREE_CODE (t
) == REALPART_EXPR
3400 || TREE_CODE (t
) == IMAGPART_EXPR
))
3401 t
= TREE_OPERAND (t
, 0);
3410 /* Called via walk_trees. Verify tree sharing. */
3413 verify_node_sharing (tree
* tp
, int *walk_subtrees
, void *data
)
3415 htab_t htab
= (htab_t
) data
;
3418 if (tree_node_can_be_shared (*tp
))
3420 *walk_subtrees
= false;
3424 slot
= htab_find_slot (htab
, *tp
, INSERT
);
3433 /* Verify the GIMPLE statement chain. */
3439 block_stmt_iterator bsi
;
3444 timevar_push (TV_TREE_STMT_VERIFY
);
3445 htab
= htab_create (37, htab_hash_pointer
, htab_eq_pointer
, NULL
);
3452 for (phi
= phi_nodes (bb
); phi
; phi
= PHI_CHAIN (phi
))
3454 int phi_num_args
= PHI_NUM_ARGS (phi
);
3456 for (i
= 0; i
< phi_num_args
; i
++)
3458 tree t
= PHI_ARG_DEF (phi
, i
);
3461 /* Addressable variables do have SSA_NAMEs but they
3462 are not considered gimple values. */
3463 if (TREE_CODE (t
) != SSA_NAME
3464 && TREE_CODE (t
) != FUNCTION_DECL
3465 && !is_gimple_val (t
))
3467 error ("PHI def is not a GIMPLE value");
3468 debug_generic_stmt (phi
);
3469 debug_generic_stmt (t
);
3473 addr
= walk_tree (&t
, verify_expr
, NULL
, NULL
);
3476 debug_generic_stmt (addr
);
3480 addr
= walk_tree (&t
, verify_node_sharing
, htab
, NULL
);
3483 error ("Incorrect sharing of tree nodes");
3484 debug_generic_stmt (phi
);
3485 debug_generic_stmt (addr
);
3491 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); )
3493 tree stmt
= bsi_stmt (bsi
);
3495 err
|= verify_stmt (stmt
, bsi_end_p (bsi
));
3496 addr
= walk_tree (&stmt
, verify_node_sharing
, htab
, NULL
);
3499 error ("Incorrect sharing of tree nodes");
3500 debug_generic_stmt (stmt
);
3501 debug_generic_stmt (addr
);
3508 internal_error ("verify_stmts failed.");
3511 timevar_pop (TV_TREE_STMT_VERIFY
);
3515 /* Verifies that the flow information is OK. */
3518 tree_verify_flow_info (void)
3522 block_stmt_iterator bsi
;
3526 if (ENTRY_BLOCK_PTR
->stmt_list
)
3528 error ("ENTRY_BLOCK has a statement list associated with it\n");
3532 if (EXIT_BLOCK_PTR
->stmt_list
)
3534 error ("EXIT_BLOCK has a statement list associated with it\n");
3538 for (e
= EXIT_BLOCK_PTR
->pred
; e
; e
= e
->pred_next
)
3539 if (e
->flags
& EDGE_FALLTHRU
)
3541 error ("Fallthru to exit from bb %d\n", e
->src
->index
);
3547 bool found_ctrl_stmt
= false;
3549 /* Skip labels on the start of basic block. */
3550 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
3552 if (TREE_CODE (bsi_stmt (bsi
)) != LABEL_EXPR
)
3555 if (label_to_block (LABEL_EXPR_LABEL (bsi_stmt (bsi
))) != bb
)
3557 error ("Label %s to block does not match in bb %d\n",
3558 IDENTIFIER_POINTER (DECL_NAME (bsi_stmt (bsi
))),
3563 if (decl_function_context (LABEL_EXPR_LABEL (bsi_stmt (bsi
)))
3564 != current_function_decl
)
3566 error ("Label %s has incorrect context in bb %d\n",
3567 IDENTIFIER_POINTER (DECL_NAME (bsi_stmt (bsi
))),
3573 /* Verify that body of basic block BB is free of control flow. */
3574 for (; !bsi_end_p (bsi
); bsi_next (&bsi
))
3576 tree stmt
= bsi_stmt (bsi
);
3578 if (found_ctrl_stmt
)
3580 error ("Control flow in the middle of basic block %d\n",
3585 if (stmt_ends_bb_p (stmt
))
3586 found_ctrl_stmt
= true;
3588 if (TREE_CODE (stmt
) == LABEL_EXPR
)
3590 error ("Label %s in the middle of basic block %d\n",
3591 IDENTIFIER_POINTER (DECL_NAME (stmt
)),
3596 bsi
= bsi_last (bb
);
3597 if (bsi_end_p (bsi
))
3600 stmt
= bsi_stmt (bsi
);
3602 if (is_ctrl_stmt (stmt
))
3604 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
3605 if (e
->flags
& EDGE_FALLTHRU
)
3607 error ("Fallthru edge after a control statement in bb %d \n",
3613 switch (TREE_CODE (stmt
))
3619 if (TREE_CODE (COND_EXPR_THEN (stmt
)) != GOTO_EXPR
3620 || TREE_CODE (COND_EXPR_ELSE (stmt
)) != GOTO_EXPR
)
3622 error ("Structured COND_EXPR at the end of bb %d\n", bb
->index
);
3626 extract_true_false_edges_from_block (bb
, &true_edge
, &false_edge
);
3628 if (!true_edge
|| !false_edge
3629 || !(true_edge
->flags
& EDGE_TRUE_VALUE
)
3630 || !(false_edge
->flags
& EDGE_FALSE_VALUE
)
3631 || (true_edge
->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
))
3632 || (false_edge
->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
))
3633 || bb
->succ
->succ_next
->succ_next
)
3635 error ("Wrong outgoing edge flags at end of bb %d\n",
3640 if (!has_label_p (true_edge
->dest
,
3641 GOTO_DESTINATION (COND_EXPR_THEN (stmt
))))
3643 error ("`then' label does not match edge at end of bb %d\n",
3648 if (!has_label_p (false_edge
->dest
,
3649 GOTO_DESTINATION (COND_EXPR_ELSE (stmt
))))
3651 error ("`else' label does not match edge at end of bb %d\n",
3659 if (simple_goto_p (stmt
))
3661 error ("Explicit goto at end of bb %d\n", bb
->index
);
3666 /* FIXME. We should double check that the labels in the
3667 destination blocks have their address taken. */
3668 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
3669 if ((e
->flags
& (EDGE_FALLTHRU
| EDGE_TRUE_VALUE
3670 | EDGE_FALSE_VALUE
))
3671 || !(e
->flags
& EDGE_ABNORMAL
))
3673 error ("Wrong outgoing edge flags at end of bb %d\n",
3681 if (!bb
->succ
|| bb
->succ
->succ_next
3682 || (bb
->succ
->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
3683 | EDGE_TRUE_VALUE
| EDGE_FALSE_VALUE
)))
3685 error ("Wrong outgoing edge flags at end of bb %d\n", bb
->index
);
3688 if (bb
->succ
->dest
!= EXIT_BLOCK_PTR
)
3690 error ("Return edge does not point to exit in bb %d\n",
3703 vec
= SWITCH_LABELS (stmt
);
3704 n
= TREE_VEC_LENGTH (vec
);
3706 /* Mark all the destination basic blocks. */
3707 for (i
= 0; i
< n
; ++i
)
3709 tree lab
= CASE_LABEL (TREE_VEC_ELT (vec
, i
));
3710 basic_block label_bb
= label_to_block (lab
);
3712 if (label_bb
->aux
&& label_bb
->aux
!= (void *)1)
3714 label_bb
->aux
= (void *)1;
3717 /* Verify that the case labels are sorted. */
3718 prev
= TREE_VEC_ELT (vec
, 0);
3719 for (i
= 1; i
< n
- 1; ++i
)
3721 tree c
= TREE_VEC_ELT (vec
, i
);
3724 error ("Found default case not at end of case vector");
3728 if (! tree_int_cst_lt (CASE_LOW (prev
), CASE_LOW (c
)))
3730 error ("Case labels not sorted:\n ");
3731 print_generic_expr (stderr
, prev
, 0);
3732 fprintf (stderr
," is greater than ");
3733 print_generic_expr (stderr
, c
, 0);
3734 fprintf (stderr
," but comes before it.\n");
3739 if (CASE_LOW (TREE_VEC_ELT (vec
, n
- 1)))
3741 error ("No default case found at end of case vector");
3745 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
3749 error ("Extra outgoing edge %d->%d\n",
3750 bb
->index
, e
->dest
->index
);
3753 e
->dest
->aux
= (void *)2;
3754 if ((e
->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
3755 | EDGE_TRUE_VALUE
| EDGE_FALSE_VALUE
)))
3757 error ("Wrong outgoing edge flags at end of bb %d\n",
3763 /* Check that we have all of them. */
3764 for (i
= 0; i
< n
; ++i
)
3766 tree lab
= CASE_LABEL (TREE_VEC_ELT (vec
, i
));
3767 basic_block label_bb
= label_to_block (lab
);
3769 if (label_bb
->aux
!= (void *)2)
3771 error ("Missing edge %i->%i\n",
3772 bb
->index
, label_bb
->index
);
3777 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
3778 e
->dest
->aux
= (void *)0;
3785 if (dom_computed
[CDI_DOMINATORS
] >= DOM_NO_FAST_QUERY
)
3786 verify_dominators (CDI_DOMINATORS
);
3792 /* Updates phi nodes after creating forwarder block joined
3793 by edge FALLTHRU. */
3796 tree_make_forwarder_block (edge fallthru
)
3799 basic_block dummy
, bb
;
3800 tree phi
, new_phi
, var
, prev
, next
;
3802 dummy
= fallthru
->src
;
3803 bb
= fallthru
->dest
;
3805 if (!bb
->pred
->pred_next
)
3808 /* If we redirected a branch we must create new phi nodes at the
3810 for (phi
= phi_nodes (dummy
); phi
; phi
= PHI_CHAIN (phi
))
3812 var
= PHI_RESULT (phi
);
3813 new_phi
= create_phi_node (var
, bb
);
3814 SSA_NAME_DEF_STMT (var
) = new_phi
;
3815 SET_PHI_RESULT (phi
, make_ssa_name (SSA_NAME_VAR (var
), phi
));
3816 add_phi_arg (&new_phi
, PHI_RESULT (phi
), fallthru
);
3819 /* Ensure that the PHI node chain is in the same order. */
3821 for (phi
= phi_nodes (bb
); phi
; phi
= next
)
3823 next
= PHI_CHAIN (phi
);
3824 PHI_CHAIN (phi
) = prev
;
3827 set_phi_nodes (bb
, prev
);
3829 /* Add the arguments we have stored on edges. */
3830 for (e
= bb
->pred
; e
; e
= e
->pred_next
)
3835 for (phi
= phi_nodes (bb
), var
= PENDING_STMT (e
);
3837 phi
= PHI_CHAIN (phi
), var
= TREE_CHAIN (var
))
3838 add_phi_arg (&phi
, TREE_VALUE (var
), e
);
3840 PENDING_STMT (e
) = NULL
;
3845 /* Return true if basic block BB does nothing except pass control
3846 flow to another block and that we can safely insert a label at
3847 the start of the successor block. */
3850 tree_forwarder_block_p (basic_block bb
)
3852 block_stmt_iterator bsi
;
3855 /* If we have already determined that this block is not forwardable,
3856 then no further checks are necessary. */
3857 if (! bb_ann (bb
)->forwardable
)
3860 /* BB must have a single outgoing normal edge. Otherwise it can not be
3861 a forwarder block. */
3863 || bb
->succ
->succ_next
3864 || bb
->succ
->dest
== EXIT_BLOCK_PTR
3865 || (bb
->succ
->flags
& EDGE_ABNORMAL
)
3866 || bb
== ENTRY_BLOCK_PTR
)
3868 bb_ann (bb
)->forwardable
= 0;
3872 /* Successors of the entry block are not forwarders. */
3873 for (e
= ENTRY_BLOCK_PTR
->succ
; e
; e
= e
->succ_next
)
3876 bb_ann (bb
)->forwardable
= 0;
3880 /* BB can not have any PHI nodes. This could potentially be relaxed
3881 early in compilation if we re-rewrote the variables appearing in
3882 any PHI nodes in forwarder blocks. */
3885 bb_ann (bb
)->forwardable
= 0;
3889 /* Now walk through the statements. We can ignore labels, anything else
3890 means this is not a forwarder block. */
3891 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
3893 tree stmt
= bsi_stmt (bsi
);
3895 switch (TREE_CODE (stmt
))
3898 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt
)))
3903 bb_ann (bb
)->forwardable
= 0;
3912 /* Thread jumps over empty statements.
3914 This code should _not_ thread over obviously equivalent conditions
3915 as that requires nontrivial updates to the SSA graph. */
3920 edge e
, next
, last
, old
;
3921 basic_block bb
, dest
, tmp
;
3924 bool retval
= false;
3927 bb_ann (bb
)->forwardable
= 1;
3929 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
, EXIT_BLOCK_PTR
, next_bb
)
3931 /* Don't waste time on unreachable blocks. */
3935 /* Nor on forwarders. */
3936 if (tree_forwarder_block_p (bb
))
3939 /* This block is now part of a forwarding path, mark it as not
3940 forwardable so that we can detect loops. This bit will be
3942 bb_ann (bb
)->forwardable
= 0;
3944 /* Examine each of our block's successors to see if it is
3946 for (e
= bb
->succ
; e
; e
= next
)
3948 next
= e
->succ_next
;
3950 /* If the edge is abnormal or its destination is not
3951 forwardable, then there's nothing to do. */
3952 if ((e
->flags
& EDGE_ABNORMAL
)
3953 || !tree_forwarder_block_p (e
->dest
))
3956 /* Now walk through as many forwarder block as possible to
3957 find the ultimate destination we want to thread our jump
3959 last
= e
->dest
->succ
;
3960 bb_ann (e
->dest
)->forwardable
= 0;
3961 for (dest
= e
->dest
->succ
->dest
;
3962 tree_forwarder_block_p (dest
);
3964 dest
= dest
->succ
->dest
)
3966 /* An infinite loop detected. We redirect the edge anyway, so
3967 that the loop is shrunk into single basic block. */
3968 if (!bb_ann (dest
)->forwardable
)
3971 if (dest
->succ
->dest
== EXIT_BLOCK_PTR
)
3974 bb_ann (dest
)->forwardable
= 0;
3977 /* Reset the forwardable marks to 1. */
3980 tmp
= tmp
->succ
->dest
)
3981 bb_ann (tmp
)->forwardable
= 1;
3983 if (dest
== e
->dest
)
3986 old
= find_edge (bb
, dest
);
3989 /* If there already is an edge, check whether the values
3990 in phi nodes differ. */
3991 if (!phi_alternatives_equal (dest
, last
, old
))
3993 /* The previous block is forwarder. Redirect our jump
3994 to that target instead since we know it has no PHI
3995 nodes that will need updating. */
3998 /* That might mean that no forwarding at all is possible. */
3999 if (dest
== e
->dest
)
4002 old
= find_edge (bb
, dest
);
4006 /* Perform the redirection. */
4008 e
= redirect_edge_and_branch (e
, dest
);
4010 /* TODO -- updating dominators in this case is simple. */
4011 free_dominance_info (CDI_DOMINATORS
);
4015 /* Update PHI nodes. We know that the new argument should
4016 have the same value as the argument associated with LAST.
4017 Otherwise we would have changed our target block above. */
4018 for (phi
= phi_nodes (dest
); phi
; phi
= PHI_CHAIN (phi
))
4020 arg
= phi_arg_from_edge (phi
, last
);
4023 add_phi_arg (&phi
, PHI_ARG_DEF (phi
, arg
), e
);
4028 /* Reset the forwardable bit on our block since it's no longer in
4029 a forwarding chain path. */
4030 bb_ann (bb
)->forwardable
= 1;
4037 /* Return a non-special label in the head of basic block BLOCK.
4038 Create one if it doesn't exist. */
4041 tree_block_label (basic_block bb
)
4043 block_stmt_iterator i
, s
= bsi_start (bb
);
4047 for (i
= s
; !bsi_end_p (i
); first
= false, bsi_next (&i
))
4049 stmt
= bsi_stmt (i
);
4050 if (TREE_CODE (stmt
) != LABEL_EXPR
)
4052 label
= LABEL_EXPR_LABEL (stmt
);
4053 if (!DECL_NONLOCAL (label
))
4056 bsi_move_before (&i
, &s
);
4061 label
= create_artificial_label ();
4062 stmt
= build1 (LABEL_EXPR
, void_type_node
, label
);
4063 bsi_insert_before (&s
, stmt
, BSI_NEW_STMT
);
4068 /* Attempt to perform edge redirection by replacing a possibly complex
4069 jump instruction by a goto or by removing the jump completely.
4070 This can apply only if all edges now point to the same block. The
4071 parameters and return values are equivalent to
4072 redirect_edge_and_branch. */
4075 tree_try_redirect_by_replacing_jump (edge e
, basic_block target
)
4077 basic_block src
= e
->src
;
4079 block_stmt_iterator b
;
4082 /* Verify that all targets will be TARGET. */
4083 for (tmp
= src
->succ
; tmp
; tmp
= tmp
->succ_next
)
4084 if (tmp
->dest
!= target
&& tmp
!= e
)
4093 stmt
= bsi_stmt (b
);
4095 if (TREE_CODE (stmt
) == COND_EXPR
4096 || TREE_CODE (stmt
) == SWITCH_EXPR
)
4099 e
= ssa_redirect_edge (e
, target
);
4100 e
->flags
= EDGE_FALLTHRU
;
4108 /* Redirect E to DEST. Return NULL on failure. Otherwise, return the
4109 edge representing the redirected branch. */
4112 tree_redirect_edge_and_branch (edge e
, basic_block dest
)
4114 basic_block bb
= e
->src
;
4115 block_stmt_iterator bsi
;
4119 if (e
->flags
& (EDGE_ABNORMAL_CALL
| EDGE_EH
))
4122 if (e
->src
!= ENTRY_BLOCK_PTR
4123 && (ret
= tree_try_redirect_by_replacing_jump (e
, dest
)))
4126 if (e
->dest
== dest
)
4129 label
= tree_block_label (dest
);
4131 bsi
= bsi_last (bb
);
4132 stmt
= bsi_end_p (bsi
) ? NULL
: bsi_stmt (bsi
);
4134 switch (stmt
? TREE_CODE (stmt
) : ERROR_MARK
)
4137 stmt
= (e
->flags
& EDGE_TRUE_VALUE
4138 ? COND_EXPR_THEN (stmt
)
4139 : COND_EXPR_ELSE (stmt
));
4140 GOTO_DESTINATION (stmt
) = label
;
4144 /* No non-abnormal edges should lead from a non-simple goto, and
4145 simple ones should be represented implicitly. */
4150 tree vec
= SWITCH_LABELS (stmt
);
4151 size_t i
, n
= TREE_VEC_LENGTH (vec
);
4153 for (i
= 0; i
< n
; ++i
)
4155 tree elt
= TREE_VEC_ELT (vec
, i
);
4156 if (label_to_block (CASE_LABEL (elt
)) == e
->dest
)
4157 CASE_LABEL (elt
) = label
;
4164 e
->flags
|= EDGE_FALLTHRU
;
4168 /* Otherwise it must be a fallthru edge, and we don't need to
4169 do anything besides redirecting it. */
4170 if (!(e
->flags
& EDGE_FALLTHRU
))
4175 /* Update/insert PHI nodes as necessary. */
4177 /* Now update the edges in the CFG. */
4178 e
= ssa_redirect_edge (e
, dest
);
4184 /* Simple wrapper, as we can always redirect fallthru edges. */
4187 tree_redirect_edge_and_branch_force (edge e
, basic_block dest
)
4189 e
= tree_redirect_edge_and_branch (e
, dest
);
4197 /* Splits basic block BB after statement STMT (but at least after the
4198 labels). If STMT is NULL, BB is split just after the labels. */
4201 tree_split_block (basic_block bb
, void *stmt
)
4203 block_stmt_iterator bsi
, bsi_tgt
;
4208 new_bb
= create_empty_bb (bb
);
4210 /* Redirect the outgoing edges. */
4211 new_bb
->succ
= bb
->succ
;
4213 for (e
= new_bb
->succ
; e
; e
= e
->succ_next
)
4216 if (stmt
&& TREE_CODE ((tree
) stmt
) == LABEL_EXPR
)
4219 /* Move everything from BSI to the new basic block. */
4220 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
4222 act
= bsi_stmt (bsi
);
4223 if (TREE_CODE (act
) == LABEL_EXPR
)
4236 bsi_tgt
= bsi_start (new_bb
);
4237 while (!bsi_end_p (bsi
))
4239 act
= bsi_stmt (bsi
);
4241 bsi_insert_after (&bsi_tgt
, act
, BSI_NEW_STMT
);
4248 /* Moves basic block BB after block AFTER. */
4251 tree_move_block_after (basic_block bb
, basic_block after
)
4253 if (bb
->prev_bb
== after
)
4257 link_block (bb
, after
);
4263 /* Return true if basic_block can be duplicated. */
4266 tree_can_duplicate_bb_p (basic_block bb ATTRIBUTE_UNUSED
)
4272 /* Create a duplicate of the basic block BB. NOTE: This does not
4273 preserve SSA form. */
4276 tree_duplicate_bb (basic_block bb
)
4279 block_stmt_iterator bsi
, bsi_tgt
;
4281 new_bb
= create_empty_bb (EXIT_BLOCK_PTR
->prev_bb
);
4282 bsi_tgt
= bsi_start (new_bb
);
4283 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
4285 tree stmt
= bsi_stmt (bsi
);
4288 if (TREE_CODE (stmt
) == LABEL_EXPR
)
4291 copy
= unshare_expr (stmt
);
4293 /* Copy also the virtual operands. */
4294 get_stmt_ann (copy
);
4295 copy_virtual_operands (copy
, stmt
);
4297 bsi_insert_after (&bsi_tgt
, copy
, BSI_NEW_STMT
);
4304 /* Dump FUNCTION_DECL FN to file FILE using FLAGS (see TDF_* in tree.h) */
4307 dump_function_to_file (tree fn
, FILE *file
, int flags
)
4309 tree arg
, vars
, var
;
4310 bool ignore_topmost_bind
= false, any_var
= false;
4314 fprintf (file
, "%s (", lang_hooks
.decl_printable_name (fn
, 2));
4316 arg
= DECL_ARGUMENTS (fn
);
4319 print_generic_expr (file
, arg
, dump_flags
);
4320 if (TREE_CHAIN (arg
))
4321 fprintf (file
, ", ");
4322 arg
= TREE_CHAIN (arg
);
4324 fprintf (file
, ")\n");
4326 if (flags
& TDF_RAW
)
4328 dump_node (fn
, TDF_SLIM
| flags
, file
);
4332 /* When GIMPLE is lowered, the variables are no longer available in
4333 BIND_EXPRs, so display them separately. */
4334 if (cfun
&& cfun
->unexpanded_var_list
)
4336 ignore_topmost_bind
= true;
4338 fprintf (file
, "{\n");
4339 for (vars
= cfun
->unexpanded_var_list
; vars
; vars
= TREE_CHAIN (vars
))
4341 var
= TREE_VALUE (vars
);
4343 print_generic_decl (file
, var
, flags
);
4344 fprintf (file
, "\n");
4350 if (basic_block_info
)
4352 /* Make a CFG based dump. */
4353 if (!ignore_topmost_bind
)
4354 fprintf (file
, "{\n");
4356 if (any_var
&& n_basic_blocks
)
4357 fprintf (file
, "\n");
4360 dump_generic_bb (file
, bb
, 2, flags
);
4362 fprintf (file
, "}\n");
4368 /* Make a tree based dump. */
4369 chain
= DECL_SAVED_TREE (fn
);
4371 if (TREE_CODE (chain
) == BIND_EXPR
)
4373 if (ignore_topmost_bind
)
4375 chain
= BIND_EXPR_BODY (chain
);
4383 if (!ignore_topmost_bind
)
4384 fprintf (file
, "{\n");
4389 fprintf (file
, "\n");
4391 print_generic_stmt_indented (file
, chain
, flags
, indent
);
4392 if (ignore_topmost_bind
)
4393 fprintf (file
, "}\n");
4396 fprintf (file
, "\n\n");
4400 /* Pretty print of the loops intermediate representation. */
4401 static void print_loop (FILE *, struct loop
*, int);
4402 static void print_pred_bbs (FILE *, edge
);
4403 static void print_succ_bbs (FILE *, edge
);
4406 /* Print the predecessors indexes of edge E on FILE. */
4409 print_pred_bbs (FILE *file
, edge e
)
4414 else if (e
->pred_next
== NULL
)
4415 fprintf (file
, "bb_%d", e
->src
->index
);
4419 fprintf (file
, "bb_%d, ", e
->src
->index
);
4420 print_pred_bbs (file
, e
->pred_next
);
4425 /* Print the successors indexes of edge E on FILE. */
4428 print_succ_bbs (FILE *file
, edge e
)
4432 else if (e
->succ_next
== NULL
)
4433 fprintf (file
, "bb_%d", e
->dest
->index
);
4436 fprintf (file
, "bb_%d, ", e
->dest
->index
);
4437 print_succ_bbs (file
, e
->succ_next
);
4442 /* Pretty print LOOP on FILE, indented INDENT spaces. */
4445 print_loop (FILE *file
, struct loop
*loop
, int indent
)
4453 s_indent
= (char *) alloca ((size_t) indent
+ 1);
4454 memset ((void *) s_indent
, ' ', (size_t) indent
);
4455 s_indent
[indent
] = '\0';
4457 /* Print the loop's header. */
4458 fprintf (file
, "%sloop_%d\n", s_indent
, loop
->num
);
4460 /* Print the loop's body. */
4461 fprintf (file
, "%s{\n", s_indent
);
4463 if (bb
->loop_father
== loop
)
4465 /* Print the basic_block's header. */
4466 fprintf (file
, "%s bb_%d (preds = {", s_indent
, bb
->index
);
4467 print_pred_bbs (file
, bb
->pred
);
4468 fprintf (file
, "}, succs = {");
4469 print_succ_bbs (file
, bb
->succ
);
4470 fprintf (file
, "})\n");
4472 /* Print the basic_block's body. */
4473 fprintf (file
, "%s {\n", s_indent
);
4474 tree_dump_bb (bb
, file
, indent
+ 4);
4475 fprintf (file
, "%s }\n", s_indent
);
4478 print_loop (file
, loop
->inner
, indent
+ 2);
4479 fprintf (file
, "%s}\n", s_indent
);
4480 print_loop (file
, loop
->next
, indent
);
4484 /* Follow a CFG edge from the entry point of the program, and on entry
4485 of a loop, pretty print the loop structure on FILE. */
4488 print_loop_ir (FILE *file
)
4492 bb
= BASIC_BLOCK (0);
4493 if (bb
&& bb
->loop_father
)
4494 print_loop (file
, bb
->loop_father
, 0);
4498 /* Debugging loops structure at tree level. */
4501 debug_loop_ir (void)
4503 print_loop_ir (stderr
);
4507 /* Return true if BB ends with a call, possibly followed by some
4508 instructions that must stay with the call. Return false,
4512 tree_block_ends_with_call_p (basic_block bb
)
4514 block_stmt_iterator bsi
= bsi_last (bb
);
4515 tree t
= tsi_stmt (bsi
.tsi
);
4517 if (TREE_CODE (t
) == RETURN_EXPR
&& TREE_OPERAND (t
, 0))
4518 t
= TREE_OPERAND (t
, 0);
4520 if (TREE_CODE (t
) == MODIFY_EXPR
)
4521 t
= TREE_OPERAND (t
, 1);
4523 return TREE_CODE (t
) == CALL_EXPR
;
4527 /* Return true if BB ends with a conditional branch. Return false,
4531 tree_block_ends_with_condjump_p (basic_block bb
)
4533 tree stmt
= tsi_stmt (bsi_last (bb
).tsi
);
4534 return (TREE_CODE (stmt
) == COND_EXPR
);
4538 /* Return true if we need to add fake edge to exit at statement T.
4539 Helper function for tree_flow_call_edges_add. */
4542 need_fake_edge_p (tree t
)
4544 if (TREE_CODE (t
) == RETURN_EXPR
&& TREE_OPERAND (t
, 0))
4545 t
= TREE_OPERAND (t
, 0);
4547 if (TREE_CODE (t
) == MODIFY_EXPR
)
4548 t
= TREE_OPERAND (t
, 1);
4550 /* NORETURN and LONGJMP calls already have an edge to exit.
4551 CONST, PURE and ALWAYS_RETURN calls do not need one.
4552 We don't currently check for CONST and PURE here, although
4553 it would be a good idea, because those attributes are
4554 figured out from the RTL in mark_constant_function, and
4555 the counter incrementation code from -fprofile-arcs
4556 leads to different results from -fbranch-probabilities. */
4557 if (TREE_CODE (t
) == CALL_EXPR
4558 && !(call_expr_flags (t
) &
4559 (ECF_NORETURN
| ECF_LONGJMP
| ECF_ALWAYS_RETURN
)))
4562 if (TREE_CODE (t
) == ASM_EXPR
4563 && (ASM_VOLATILE_P (t
) || ASM_INPUT_P (t
)))
4570 /* Add fake edges to the function exit for any non constant and non
4571 noreturn calls, volatile inline assembly in the bitmap of blocks
4572 specified by BLOCKS or to the whole CFG if BLOCKS is zero. Return
4573 the number of blocks that were split.
4575 The goal is to expose cases in which entering a basic block does
4576 not imply that all subsequent instructions must be executed. */
4579 tree_flow_call_edges_add (sbitmap blocks
)
4582 int blocks_split
= 0;
4583 int last_bb
= last_basic_block
;
4584 bool check_last_block
= false;
4586 if (n_basic_blocks
== 0)
4590 check_last_block
= true;
4592 check_last_block
= TEST_BIT (blocks
, EXIT_BLOCK_PTR
->prev_bb
->index
);
4594 /* In the last basic block, before epilogue generation, there will be
4595 a fallthru edge to EXIT. Special care is required if the last insn
4596 of the last basic block is a call because make_edge folds duplicate
4597 edges, which would result in the fallthru edge also being marked
4598 fake, which would result in the fallthru edge being removed by
4599 remove_fake_edges, which would result in an invalid CFG.
4601 Moreover, we can't elide the outgoing fake edge, since the block
4602 profiler needs to take this into account in order to solve the minimal
4603 spanning tree in the case that the call doesn't return.
4605 Handle this by adding a dummy instruction in a new last basic block. */
4606 if (check_last_block
)
4608 basic_block bb
= EXIT_BLOCK_PTR
->prev_bb
;
4609 block_stmt_iterator bsi
= bsi_last (bb
);
4611 if (!bsi_end_p (bsi
))
4614 if (need_fake_edge_p (t
))
4618 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
4619 if (e
->dest
== EXIT_BLOCK_PTR
)
4621 bsi_insert_on_edge (e
, build_empty_stmt ());
4622 bsi_commit_edge_inserts ((int *)NULL
);
4628 /* Now add fake edges to the function exit for any non constant
4629 calls since there is no way that we can determine if they will
4631 for (i
= 0; i
< last_bb
; i
++)
4633 basic_block bb
= BASIC_BLOCK (i
);
4634 block_stmt_iterator bsi
;
4635 tree stmt
, last_stmt
;
4640 if (blocks
&& !TEST_BIT (blocks
, i
))
4643 bsi
= bsi_last (bb
);
4644 if (!bsi_end_p (bsi
))
4646 last_stmt
= bsi_stmt (bsi
);
4649 stmt
= bsi_stmt (bsi
);
4650 if (need_fake_edge_p (stmt
))
4653 /* The handling above of the final block before the
4654 epilogue should be enough to verify that there is
4655 no edge to the exit block in CFG already.
4656 Calling make_edge in such case would cause us to
4657 mark that edge as fake and remove it later. */
4658 #ifdef ENABLE_CHECKING
4659 if (stmt
== last_stmt
)
4660 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
4661 if (e
->dest
== EXIT_BLOCK_PTR
)
4665 /* Note that the following may create a new basic block
4666 and renumber the existing basic blocks. */
4667 if (stmt
!= last_stmt
)
4669 e
= split_block (bb
, stmt
);
4673 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
4677 while (!bsi_end_p (bsi
));
4682 verify_flow_info ();
4684 return blocks_split
;
4688 tree_purge_dead_eh_edges (basic_block bb
)
4690 bool changed
= false;
4692 tree stmt
= last_stmt (bb
);
4694 if (stmt
&& tree_can_throw_internal (stmt
))
4697 for (e
= bb
->succ
; e
; e
= next
)
4699 next
= e
->succ_next
;
4700 if (e
->flags
& EDGE_EH
)
4702 ssa_remove_edge (e
);
4711 tree_purge_all_dead_eh_edges (bitmap blocks
)
4713 bool changed
= false;
4716 EXECUTE_IF_SET_IN_BITMAP (blocks
, 0, i
,
4717 { changed
|= tree_purge_dead_eh_edges (BASIC_BLOCK (i
)); });
4722 struct cfg_hooks tree_cfg_hooks
= {
4724 tree_verify_flow_info
,
4725 tree_dump_bb
, /* dump_bb */
4726 create_bb
, /* create_basic_block */
4727 tree_redirect_edge_and_branch
,/* redirect_edge_and_branch */
4728 tree_redirect_edge_and_branch_force
,/* redirect_edge_and_branch_force */
4729 remove_bb
, /* delete_basic_block */
4730 tree_split_block
, /* split_block */
4731 tree_move_block_after
, /* move_block_after */
4732 tree_can_merge_blocks_p
, /* can_merge_blocks_p */
4733 tree_merge_blocks
, /* merge_blocks */
4734 tree_predict_edge
, /* predict_edge */
4735 tree_predicted_by_p
, /* predicted_by_p */
4736 tree_can_duplicate_bb_p
, /* can_duplicate_block_p */
4737 tree_duplicate_bb
, /* duplicate_block */
4738 tree_split_edge
, /* split_edge */
4739 tree_make_forwarder_block
, /* make_forward_block */
4740 NULL
, /* tidy_fallthru_edge */
4741 tree_block_ends_with_call_p
, /* block_ends_with_call_p */
4742 tree_block_ends_with_condjump_p
, /* block_ends_with_condjump_p */
4743 tree_flow_call_edges_add
/* flow_call_edges_add */
4747 /* Split all critical edges. */
4750 split_critical_edges (void)
4757 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
4758 if (EDGE_CRITICAL_P (e
) && !(e
->flags
& EDGE_ABNORMAL
))
4765 struct tree_opt_pass pass_split_crit_edges
=
4767 "crited", /* name */
4769 split_critical_edges
, /* execute */
4772 0, /* static_pass_number */
4773 TV_TREE_SPLIT_EDGES
, /* tv_id */
4774 PROP_cfg
, /* properties required */
4775 PROP_no_crit_edges
, /* properties_provided */
4776 0, /* properties_destroyed */
4777 0, /* todo_flags_start */
4778 TODO_dump_func
, /* todo_flags_finish */
4781 /* Emit return warnings. */
4784 execute_warn_function_return (void)
4786 #ifdef USE_MAPPED_LOCATION
4787 source_location location
;
4794 if (warn_missing_noreturn
4795 && !TREE_THIS_VOLATILE (cfun
->decl
)
4796 && EXIT_BLOCK_PTR
->pred
== NULL
4797 && !lang_hooks
.function
.missing_noreturn_ok_p (cfun
->decl
))
4798 warning ("%Jfunction might be possible candidate for attribute `noreturn'",
4801 /* If we have a path to EXIT, then we do return. */
4802 if (TREE_THIS_VOLATILE (cfun
->decl
)
4803 && EXIT_BLOCK_PTR
->pred
!= NULL
)
4805 #ifdef USE_MAPPED_LOCATION
4806 location
= UNKNOWN_LOCATION
;
4810 for (e
= EXIT_BLOCK_PTR
->pred
; e
; e
= e
->pred_next
)
4812 last
= last_stmt (e
->src
);
4813 if (TREE_CODE (last
) == RETURN_EXPR
4814 #ifdef USE_MAPPED_LOCATION
4815 && (location
= EXPR_LOCATION (last
)) != UNKNOWN_LOCATION
)
4817 && (locus
= EXPR_LOCUS (last
)) != NULL
)
4821 #ifdef USE_MAPPED_LOCATION
4822 if (location
== UNKNOWN_LOCATION
)
4823 location
= cfun
->function_end_locus
;
4824 warning ("%H`noreturn' function does return", &location
);
4827 locus
= &cfun
->function_end_locus
;
4828 warning ("%H`noreturn' function does return", locus
);
4832 /* If we see "return;" in some basic block, then we do reach the end
4833 without returning a value. */
4834 else if (warn_return_type
4835 && EXIT_BLOCK_PTR
->pred
!= NULL
4836 && !VOID_TYPE_P (TREE_TYPE (TREE_TYPE (cfun
->decl
))))
4838 for (e
= EXIT_BLOCK_PTR
->pred
; e
; e
= e
->pred_next
)
4840 tree last
= last_stmt (e
->src
);
4841 if (TREE_CODE (last
) == RETURN_EXPR
4842 && TREE_OPERAND (last
, 0) == NULL
)
4844 #ifdef USE_MAPPED_LOCATION
4845 location
= EXPR_LOCATION (last
);
4846 if (location
== UNKNOWN_LOCATION
)
4847 location
= cfun
->function_end_locus
;
4848 warning ("%Hcontrol reaches end of non-void function", &location
);
4850 locus
= EXPR_LOCUS (last
);
4852 locus
= &cfun
->function_end_locus
;
4853 warning ("%Hcontrol reaches end of non-void function", locus
);
4862 /* Given a basic block B which ends with a conditional and has
4863 precisely two successors, determine which of the edges is taken if
4864 the conditional is true and which is taken if the conditional is
4865 false. Set TRUE_EDGE and FALSE_EDGE appropriately. */
4868 extract_true_false_edges_from_block (basic_block b
,
4874 if (e
->flags
& EDGE_TRUE_VALUE
)
4877 *false_edge
= e
->succ_next
;
4882 *true_edge
= e
->succ_next
;
4886 struct tree_opt_pass pass_warn_function_return
=
4890 execute_warn_function_return
, /* execute */
4893 0, /* static_pass_number */
4895 PROP_cfg
, /* properties_required */
4896 0, /* properties_provided */
4897 0, /* properties_destroyed */
4898 0, /* todo_flags_start */
4899 0 /* todo_flags_finish */
4902 #include "gt-tree-cfg.h"