1 /* Control flow functions for trees.
2 Copyright (C) 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
3 Contributed by Diego Novillo <dnovillo@redhat.com>
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 GCC is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to
19 the Free Software Foundation, 59 Temple Place - Suite 330,
20 Boston, MA 02111-1307, USA. */
24 #include "coretypes.h"
29 #include "hard-reg-set.h"
30 #include "basic-block.h"
37 #include "langhooks.h"
38 #include "diagnostic.h"
39 #include "tree-flow.h"
41 #include "tree-dump.h"
42 #include "tree-pass.h"
47 /* This file contains functions for building the Control Flow Graph (CFG)
48 for a function tree. */
50 /* Local declarations. */
52 /* Initial capacity for the basic block array. */
53 static const int initial_cfg_capacity
= 20;
55 /* Mapping of labels to their associated blocks. This can greatly speed up
56 building of the CFG in code with lots of gotos. */
57 static GTY(()) varray_type label_to_block_map
;
62 long num_merged_labels
;
65 static struct cfg_stats_d cfg_stats
;
67 /* Nonzero if we found a computed goto while building basic blocks. */
68 static bool found_computed_goto
;
70 /* Basic blocks and flowgraphs. */
71 static basic_block
create_bb (void *, void *, basic_block
);
72 static void create_block_annotation (basic_block
);
73 static void free_blocks_annotations (void);
74 static void clear_blocks_annotations (void);
75 static void make_blocks (tree
);
76 static void factor_computed_gotos (void);
79 static void make_edges (void);
80 static void make_ctrl_stmt_edges (basic_block
);
81 static void make_exit_edges (basic_block
);
82 static void make_cond_expr_edges (basic_block
);
83 static void make_switch_expr_edges (basic_block
);
84 static void make_goto_expr_edges (basic_block
);
85 static edge
tree_redirect_edge_and_branch (edge
, basic_block
);
86 static edge
tree_try_redirect_by_replacing_jump (edge
, basic_block
);
87 static void split_critical_edges (void);
89 /* Various helpers. */
90 static inline bool stmt_starts_bb_p (tree
, tree
);
91 static int tree_verify_flow_info (void);
92 static void tree_make_forwarder_block (edge
);
93 static bool thread_jumps (void);
94 static bool tree_forwarder_block_p (basic_block
);
95 static void bsi_commit_edge_inserts_1 (edge e
);
96 static void tree_cfg2vcg (FILE *);
98 /* Flowgraph optimization and cleanup. */
99 static void tree_merge_blocks (basic_block
, basic_block
);
100 static bool tree_can_merge_blocks_p (basic_block
, basic_block
);
101 static void remove_bb (basic_block
);
102 static bool cleanup_control_flow (void);
103 static bool cleanup_control_expr_graph (basic_block
, block_stmt_iterator
);
104 static edge
find_taken_edge_cond_expr (basic_block
, tree
);
105 static edge
find_taken_edge_switch_expr (basic_block
, tree
);
106 static tree
find_case_label_for_value (tree
, tree
);
107 static bool phi_alternatives_equal (basic_block
, edge
, edge
);
110 /*---------------------------------------------------------------------------
112 ---------------------------------------------------------------------------*/
114 /* Entry point to the CFG builder for trees. TP points to the list of
115 statements to be added to the flowgraph. */
118 build_tree_cfg (tree
*tp
)
120 /* Register specific tree functions. */
121 tree_register_cfg_hooks ();
123 /* Initialize rbi_pool. */
126 /* Initialize the basic block array. */
128 profile_status
= PROFILE_ABSENT
;
130 last_basic_block
= 0;
131 VARRAY_BB_INIT (basic_block_info
, initial_cfg_capacity
, "basic_block_info");
132 memset ((void *) &cfg_stats
, 0, sizeof (cfg_stats
));
134 /* Build a mapping of labels to their associated blocks. */
135 VARRAY_BB_INIT (label_to_block_map
, initial_cfg_capacity
,
136 "label to block map");
138 ENTRY_BLOCK_PTR
->next_bb
= EXIT_BLOCK_PTR
;
139 EXIT_BLOCK_PTR
->prev_bb
= ENTRY_BLOCK_PTR
;
141 found_computed_goto
= 0;
144 /* Computed gotos are hell to deal with, especially if there are
145 lots of them with a large number of destinations. So we factor
146 them to a common computed goto location before we build the
147 edge list. After we convert back to normal form, we will un-factor
148 the computed gotos since factoring introduces an unwanted jump. */
149 if (found_computed_goto
)
150 factor_computed_gotos ();
152 /* Make sure there is always at least one block, even if its empty. */
153 if (n_basic_blocks
== 0)
154 create_empty_bb (ENTRY_BLOCK_PTR
);
156 create_block_annotation (ENTRY_BLOCK_PTR
);
157 create_block_annotation (EXIT_BLOCK_PTR
);
159 /* Adjust the size of the array. */
160 VARRAY_GROW (basic_block_info
, n_basic_blocks
);
162 /* To speed up statement iterator walks, we first purge dead labels. */
163 cleanup_dead_labels ();
165 /* Group case nodes to reduce the number of edges.
166 We do this after cleaning up dead labels because otherwise we miss
167 a lot of obvious case merging opportunities. */
168 group_case_labels ();
170 /* Create the edges of the flowgraph. */
173 /* Debugging dumps. */
175 /* Write the flowgraph to a VCG file. */
177 int local_dump_flags
;
178 FILE *dump_file
= dump_begin (TDI_vcg
, &local_dump_flags
);
181 tree_cfg2vcg (dump_file
);
182 dump_end (TDI_vcg
, dump_file
);
186 /* Dump a textual representation of the flowgraph. */
188 dump_tree_cfg (dump_file
, dump_flags
);
192 execute_build_cfg (void)
194 build_tree_cfg (&DECL_SAVED_TREE (current_function_decl
));
197 struct tree_opt_pass pass_build_cfg
=
201 execute_build_cfg
, /* execute */
204 0, /* static_pass_number */
205 TV_TREE_CFG
, /* tv_id */
206 PROP_gimple_leh
, /* properties_required */
207 PROP_cfg
, /* properties_provided */
208 0, /* properties_destroyed */
209 0, /* todo_flags_start */
210 TODO_verify_stmts
, /* todo_flags_finish */
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 gcc_assert (!bb
->tree_annotations
);
298 bb
->tree_annotations
= ggc_alloc_cleared (sizeof (struct bb_ann_d
));
302 /* Free the annotations for all the basic blocks. */
304 static void free_blocks_annotations (void)
306 clear_blocks_annotations ();
310 /* Clear the annotations for all the basic blocks. */
313 clear_blocks_annotations (void)
317 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
, NULL
, next_bb
)
318 bb
->tree_annotations
= NULL
;
322 /* Build a flowgraph for the statement_list STMT_LIST. */
325 make_blocks (tree stmt_list
)
327 tree_stmt_iterator i
= tsi_start (stmt_list
);
329 bool start_new_block
= true;
330 bool first_stmt_of_list
= true;
331 basic_block bb
= ENTRY_BLOCK_PTR
;
333 while (!tsi_end_p (i
))
340 /* If the statement starts a new basic block or if we have determined
341 in a previous pass that we need to create a new block for STMT, do
343 if (start_new_block
|| stmt_starts_bb_p (stmt
, prev_stmt
))
345 if (!first_stmt_of_list
)
346 stmt_list
= tsi_split_statement_list_before (&i
);
347 bb
= create_basic_block (stmt_list
, NULL
, bb
);
348 start_new_block
= false;
351 /* Now add STMT to BB and create the subgraphs for special statement
353 set_bb_for_stmt (stmt
, bb
);
355 if (computed_goto_p (stmt
))
356 found_computed_goto
= true;
358 /* If STMT is a basic block terminator, set START_NEW_BLOCK for the
360 if (stmt_ends_bb_p (stmt
))
361 start_new_block
= true;
364 first_stmt_of_list
= false;
369 /* Create and return a new empty basic block after bb AFTER. */
372 create_bb (void *h
, void *e
, basic_block after
)
378 /* Create and initialize a new basic block. */
380 memset (bb
, 0, sizeof (*bb
));
382 bb
->index
= last_basic_block
;
384 bb
->stmt_list
= h
? h
: alloc_stmt_list ();
386 /* Add the new block to the linked list of blocks. */
387 link_block (bb
, after
);
389 /* Grow the basic block array if needed. */
390 if ((size_t) last_basic_block
== VARRAY_SIZE (basic_block_info
))
392 size_t new_size
= last_basic_block
+ (last_basic_block
+ 3) / 4;
393 VARRAY_GROW (basic_block_info
, new_size
);
396 /* Add the newly created block to the array. */
397 BASIC_BLOCK (last_basic_block
) = bb
;
399 create_block_annotation (bb
);
404 initialize_bb_rbi (bb
);
409 /*---------------------------------------------------------------------------
411 ---------------------------------------------------------------------------*/
413 /* Join all the blocks in the flowgraph. */
420 /* Create an edge from entry to the first block with executable
422 make_edge (ENTRY_BLOCK_PTR
, BASIC_BLOCK (0), EDGE_FALLTHRU
);
424 /* Traverse basic block array placing edges. */
427 tree first
= first_stmt (bb
);
428 tree last
= last_stmt (bb
);
432 /* Edges for statements that always alter flow control. */
433 if (is_ctrl_stmt (last
))
434 make_ctrl_stmt_edges (bb
);
436 /* Edges for statements that sometimes alter flow control. */
437 if (is_ctrl_altering_stmt (last
))
438 make_exit_edges (bb
);
441 /* Finally, if no edges were created above, this is a regular
442 basic block that only needs a fallthru edge. */
443 if (bb
->succ
== NULL
)
444 make_edge (bb
, bb
->next_bb
, EDGE_FALLTHRU
);
447 /* We do not care about fake edges, so remove any that the CFG
448 builder inserted for completeness. */
449 remove_fake_exit_edges ();
451 /* Clean up the graph and warn for unreachable code. */
456 /* Create edges for control statement at basic block BB. */
459 make_ctrl_stmt_edges (basic_block bb
)
461 tree last
= last_stmt (bb
);
464 switch (TREE_CODE (last
))
467 make_goto_expr_edges (bb
);
471 make_edge (bb
, EXIT_BLOCK_PTR
, 0);
475 make_cond_expr_edges (bb
);
479 make_switch_expr_edges (bb
);
483 make_eh_edges (last
);
484 /* Yet another NORETURN hack. */
485 if (bb
->succ
== NULL
)
486 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
495 /* Create exit edges for statements in block BB that alter the flow of
496 control. Statements that alter the control flow are 'goto', 'return'
497 and calls to non-returning functions. */
500 make_exit_edges (basic_block bb
)
502 tree last
= last_stmt (bb
), op
;
505 switch (TREE_CODE (last
))
508 /* If this function receives a nonlocal goto, then we need to
509 make edges from this call site to all the nonlocal goto
511 if (TREE_SIDE_EFFECTS (last
)
512 && current_function_has_nonlocal_label
)
513 make_goto_expr_edges (bb
);
515 /* If this statement has reachable exception handlers, then
516 create abnormal edges to them. */
517 make_eh_edges (last
);
519 /* Some calls are known not to return. For such calls we create
522 We really need to revamp how we build edges so that it's not
523 such a bloody pain to avoid creating edges for this case since
524 all we do is remove these edges when we're done building the
526 if (call_expr_flags (last
) & (ECF_NORETURN
| ECF_LONGJMP
))
528 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
532 /* Don't forget the fall-thru edge. */
533 make_edge (bb
, bb
->next_bb
, EDGE_FALLTHRU
);
537 /* A MODIFY_EXPR may have a CALL_EXPR on its RHS and the CALL_EXPR
538 may have an abnormal edge. Search the RHS for this case and
539 create any required edges. */
540 op
= get_call_expr_in (last
);
541 if (op
&& TREE_SIDE_EFFECTS (op
)
542 && current_function_has_nonlocal_label
)
543 make_goto_expr_edges (bb
);
545 make_eh_edges (last
);
546 make_edge (bb
, bb
->next_bb
, EDGE_FALLTHRU
);
555 /* Create the edges for a COND_EXPR starting at block BB.
556 At this point, both clauses must contain only simple gotos. */
559 make_cond_expr_edges (basic_block bb
)
561 tree entry
= last_stmt (bb
);
562 basic_block then_bb
, else_bb
;
563 tree then_label
, else_label
;
566 gcc_assert (TREE_CODE (entry
) == COND_EXPR
);
568 /* Entry basic blocks for each component. */
569 then_label
= GOTO_DESTINATION (COND_EXPR_THEN (entry
));
570 else_label
= GOTO_DESTINATION (COND_EXPR_ELSE (entry
));
571 then_bb
= label_to_block (then_label
);
572 else_bb
= label_to_block (else_label
);
574 make_edge (bb
, then_bb
, EDGE_TRUE_VALUE
);
575 make_edge (bb
, else_bb
, EDGE_FALSE_VALUE
);
579 /* Create the edges for a SWITCH_EXPR starting at block BB.
580 At this point, the switch body has been lowered and the
581 SWITCH_LABELS filled in, so this is in effect a multi-way branch. */
584 make_switch_expr_edges (basic_block bb
)
586 tree entry
= last_stmt (bb
);
590 vec
= SWITCH_LABELS (entry
);
591 n
= TREE_VEC_LENGTH (vec
);
593 for (i
= 0; i
< n
; ++i
)
595 tree lab
= CASE_LABEL (TREE_VEC_ELT (vec
, i
));
596 basic_block label_bb
= label_to_block (lab
);
597 make_edge (bb
, label_bb
, 0);
602 /* Return the basic block holding label DEST. */
605 label_to_block (tree dest
)
607 int uid
= LABEL_DECL_UID (dest
);
609 /* We would die hard when faced by undefined label. Emit label to
610 very first basic block. This will hopefully make even the dataflow
611 and undefined variable warnings quite right. */
612 if ((errorcount
|| sorrycount
) && uid
< 0)
614 block_stmt_iterator bsi
= bsi_start (BASIC_BLOCK (0));
617 stmt
= build1 (LABEL_EXPR
, void_type_node
, dest
);
618 bsi_insert_before (&bsi
, stmt
, BSI_NEW_STMT
);
619 uid
= LABEL_DECL_UID (dest
);
621 return VARRAY_BB (label_to_block_map
, uid
);
625 /* Create edges for a goto statement at block BB. */
628 make_goto_expr_edges (basic_block bb
)
631 basic_block target_bb
;
633 block_stmt_iterator last
= bsi_last (bb
);
635 goto_t
= bsi_stmt (last
);
637 /* If the last statement is not a GOTO (i.e., it is a RETURN_EXPR,
638 CALL_EXPR or MODIFY_EXPR), then the edge is an abnormal edge resulting
639 from a nonlocal goto. */
640 if (TREE_CODE (goto_t
) != GOTO_EXPR
)
642 dest
= error_mark_node
;
647 dest
= GOTO_DESTINATION (goto_t
);
650 /* A GOTO to a local label creates normal edges. */
651 if (simple_goto_p (goto_t
))
653 edge e
= make_edge (bb
, label_to_block (dest
), EDGE_FALLTHRU
);
654 #ifdef USE_MAPPED_LOCATION
655 e
->goto_locus
= EXPR_LOCATION (goto_t
);
657 e
->goto_locus
= EXPR_LOCUS (goto_t
);
663 /* Nothing more to do for nonlocal gotos. */
664 if (TREE_CODE (dest
) == LABEL_DECL
)
667 /* Computed gotos remain. */
670 /* Look for the block starting with the destination label. In the
671 case of a computed goto, make an edge to any label block we find
673 FOR_EACH_BB (target_bb
)
675 block_stmt_iterator bsi
;
677 for (bsi
= bsi_start (target_bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
679 tree target
= bsi_stmt (bsi
);
681 if (TREE_CODE (target
) != LABEL_EXPR
)
685 /* Computed GOTOs. Make an edge to every label block that has
686 been marked as a potential target for a computed goto. */
687 (FORCED_LABEL (LABEL_EXPR_LABEL (target
)) && for_call
== 0)
688 /* Nonlocal GOTO target. Make an edge to every label block
689 that has been marked as a potential target for a nonlocal
691 || (DECL_NONLOCAL (LABEL_EXPR_LABEL (target
)) && for_call
== 1))
693 make_edge (bb
, target_bb
, EDGE_ABNORMAL
);
699 /* Degenerate case of computed goto with no labels. */
700 if (!for_call
&& !bb
->succ
)
701 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
705 /*---------------------------------------------------------------------------
707 ---------------------------------------------------------------------------*/
709 /* Remove unreachable blocks and other miscellaneous clean up work. */
712 cleanup_tree_cfg (void)
714 bool something_changed
= true;
717 timevar_push (TV_TREE_CLEANUP_CFG
);
719 /* These three transformations can cascade, so we iterate on them until
721 while (something_changed
)
723 something_changed
= cleanup_control_flow ();
724 something_changed
|= delete_unreachable_blocks ();
725 something_changed
|= thread_jumps ();
726 retval
|= something_changed
;
729 /* Merging the blocks creates no new opportunities for the other
730 optimizations, so do it here. */
735 #ifdef ENABLE_CHECKING
738 timevar_pop (TV_TREE_CLEANUP_CFG
);
743 /* Cleanup useless labels in basic blocks. This is something we wish
744 to do early because it allows us to group case labels before creating
745 the edges for the CFG, and it speeds up block statement iterators in
747 We only run this pass once, running it more than once is probably not
750 /* A map from basic block index to the leading label of that block. */
751 static tree
*label_for_bb
;
753 /* Callback for for_each_eh_region. Helper for cleanup_dead_labels. */
755 update_eh_label (struct eh_region
*region
)
757 tree old_label
= get_eh_region_tree_label (region
);
761 basic_block bb
= label_to_block (old_label
);
763 /* ??? After optimizing, there may be EH regions with labels
764 that have already been removed from the function body, so
765 there is no basic block for them. */
769 new_label
= label_for_bb
[bb
->index
];
770 set_eh_region_tree_label (region
, new_label
);
774 /* Given LABEL return the first label in the same basic block. */
776 main_block_label (tree label
)
778 basic_block bb
= label_to_block (label
);
780 /* label_to_block possibly inserted undefined label into the chain. */
781 if (!label_for_bb
[bb
->index
])
782 label_for_bb
[bb
->index
] = label
;
783 return label_for_bb
[bb
->index
];
786 /* Cleanup redundant labels. This is a three-steo process:
787 1) Find the leading label for each block.
788 2) Redirect all references to labels to the leading labels.
789 3) Cleanup all useless labels. */
792 cleanup_dead_labels (void)
795 label_for_bb
= xcalloc (last_basic_block
, sizeof (tree
));
797 /* Find a suitable label for each block. We use the first user-defined
798 label is there is one, or otherwise just the first label we see. */
801 block_stmt_iterator i
;
803 for (i
= bsi_start (bb
); !bsi_end_p (i
); bsi_next (&i
))
805 tree label
, stmt
= bsi_stmt (i
);
807 if (TREE_CODE (stmt
) != LABEL_EXPR
)
810 label
= LABEL_EXPR_LABEL (stmt
);
812 /* If we have not yet seen a label for the current block,
813 remember this one and see if there are more labels. */
814 if (! label_for_bb
[bb
->index
])
816 label_for_bb
[bb
->index
] = label
;
820 /* If we did see a label for the current block already, but it
821 is an artificially created label, replace it if the current
822 label is a user defined label. */
823 if (! DECL_ARTIFICIAL (label
)
824 && DECL_ARTIFICIAL (label_for_bb
[bb
->index
]))
826 label_for_bb
[bb
->index
] = label
;
832 /* Now redirect all jumps/branches to the selected label.
833 First do so for each block ending in a control statement. */
836 tree stmt
= last_stmt (bb
);
840 switch (TREE_CODE (stmt
))
844 tree true_branch
, false_branch
;
846 true_branch
= COND_EXPR_THEN (stmt
);
847 false_branch
= COND_EXPR_ELSE (stmt
);
849 GOTO_DESTINATION (true_branch
)
850 = main_block_label (GOTO_DESTINATION (true_branch
));
851 GOTO_DESTINATION (false_branch
)
852 = main_block_label (GOTO_DESTINATION (false_branch
));
860 tree vec
= SWITCH_LABELS (stmt
);
861 size_t n
= TREE_VEC_LENGTH (vec
);
863 /* Replace all destination labels. */
864 for (i
= 0; i
< n
; ++i
)
865 CASE_LABEL (TREE_VEC_ELT (vec
, i
))
866 = main_block_label (CASE_LABEL (TREE_VEC_ELT (vec
, i
)));
871 /* We have to handle GOTO_EXPRs until they're removed, and we don't
872 remove them until after we've created the CFG edges. */
874 if (! computed_goto_p (stmt
))
876 GOTO_DESTINATION (stmt
)
877 = main_block_label (GOTO_DESTINATION (stmt
));
886 for_each_eh_region (update_eh_label
);
888 /* Finally, purge dead labels. All user-defined labels and labels that
889 can be the target of non-local gotos are preserved. */
892 block_stmt_iterator i
;
893 tree label_for_this_bb
= label_for_bb
[bb
->index
];
895 if (! label_for_this_bb
)
898 for (i
= bsi_start (bb
); !bsi_end_p (i
); )
900 tree label
, stmt
= bsi_stmt (i
);
902 if (TREE_CODE (stmt
) != LABEL_EXPR
)
905 label
= LABEL_EXPR_LABEL (stmt
);
907 if (label
== label_for_this_bb
908 || ! DECL_ARTIFICIAL (label
)
909 || DECL_NONLOCAL (label
))
919 /* Look for blocks ending in a multiway branch (a SWITCH_EXPR in GIMPLE),
920 and scan the sorted vector of cases. Combine the ones jumping to the
922 Eg. three separate entries 1: 2: 3: become one entry 1..3: */
925 group_case_labels (void)
931 tree stmt
= last_stmt (bb
);
932 if (stmt
&& TREE_CODE (stmt
) == SWITCH_EXPR
)
934 tree labels
= SWITCH_LABELS (stmt
);
935 int old_size
= TREE_VEC_LENGTH (labels
);
936 int i
, j
, new_size
= old_size
;
937 tree default_label
= TREE_VEC_ELT (labels
, old_size
- 1);
939 /* Look for possible opportunities to merge cases.
940 Ignore the last element of the label vector because it
941 must be the default case. */
943 while (i
< old_size
- 2)
945 tree base_case
, base_label
, base_high
, type
;
946 base_case
= TREE_VEC_ELT (labels
, i
);
948 gcc_assert (base_case
);
949 base_label
= CASE_LABEL (base_case
);
951 /* Discard cases that have the same destination as the
953 if (base_label
== default_label
)
955 TREE_VEC_ELT (labels
, i
) = NULL_TREE
;
960 type
= TREE_TYPE (CASE_LOW (base_case
));
961 base_high
= CASE_HIGH (base_case
) ?
962 CASE_HIGH (base_case
) : CASE_LOW (base_case
);
964 /* Try to merge case labels. Break out when we reach the end
965 of the label vector or when we cannot merge the next case
966 label with the current one. */
967 while (i
< old_size
- 2)
969 tree merge_case
= TREE_VEC_ELT (labels
, ++i
);
970 tree merge_label
= CASE_LABEL (merge_case
);
971 tree t
= int_const_binop (PLUS_EXPR
, base_high
,
972 integer_one_node
, 1);
974 /* Merge the cases if they jump to the same place,
975 and their ranges are consecutive. */
976 if (merge_label
== base_label
977 && tree_int_cst_equal (CASE_LOW (merge_case
), t
))
979 base_high
= CASE_HIGH (merge_case
) ?
980 CASE_HIGH (merge_case
) : CASE_LOW (merge_case
);
981 CASE_HIGH (base_case
) = base_high
;
982 TREE_VEC_ELT (labels
, i
) = NULL_TREE
;
990 /* Compress the case labels in the label vector, and adjust the
991 length of the vector. */
992 for (i
= 0, j
= 0; i
< new_size
; i
++)
994 while (! TREE_VEC_ELT (labels
, j
))
996 TREE_VEC_ELT (labels
, i
) = TREE_VEC_ELT (labels
, j
++);
998 TREE_VEC_LENGTH (labels
) = new_size
;
1003 /* Checks whether we can merge block B into block A. */
1006 tree_can_merge_blocks_p (basic_block a
, basic_block b
)
1009 block_stmt_iterator bsi
;
1012 || a
->succ
->succ_next
)
1015 if (a
->succ
->flags
& EDGE_ABNORMAL
)
1018 if (a
->succ
->dest
!= b
)
1021 if (b
== EXIT_BLOCK_PTR
)
1024 if (b
->pred
->pred_next
)
1027 /* If A ends by a statement causing exceptions or something similar, we
1028 cannot merge the blocks. */
1029 stmt
= last_stmt (a
);
1030 if (stmt
&& stmt_ends_bb_p (stmt
))
1033 /* Do not allow a block with only a non-local label to be merged. */
1034 if (stmt
&& TREE_CODE (stmt
) == LABEL_EXPR
1035 && DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt
)))
1038 /* There may be no phi nodes at the start of b. Most of these degenerate
1039 phi nodes should be cleaned up by kill_redundant_phi_nodes. */
1043 /* Do not remove user labels. */
1044 for (bsi
= bsi_start (b
); !bsi_end_p (bsi
); bsi_next (&bsi
))
1046 stmt
= bsi_stmt (bsi
);
1047 if (TREE_CODE (stmt
) != LABEL_EXPR
)
1049 if (!DECL_ARTIFICIAL (LABEL_EXPR_LABEL (stmt
)))
1057 /* Merge block B into block A. */
1060 tree_merge_blocks (basic_block a
, basic_block b
)
1062 block_stmt_iterator bsi
;
1063 tree_stmt_iterator last
;
1066 fprintf (dump_file
, "Merging blocks %d and %d\n", a
->index
, b
->index
);
1068 /* Ensure that B follows A. */
1069 move_block_after (b
, a
);
1071 gcc_assert (a
->succ
->flags
& EDGE_FALLTHRU
);
1072 gcc_assert (!last_stmt (a
) || !stmt_ends_bb_p (last_stmt (a
)));
1074 /* Remove labels from B and set bb_for_stmt to A for other statements. */
1075 for (bsi
= bsi_start (b
); !bsi_end_p (bsi
);)
1077 if (TREE_CODE (bsi_stmt (bsi
)) == LABEL_EXPR
)
1081 set_bb_for_stmt (bsi_stmt (bsi
), a
);
1086 /* Merge the chains. */
1087 last
= tsi_last (a
->stmt_list
);
1088 tsi_link_after (&last
, b
->stmt_list
, TSI_NEW_STMT
);
1089 b
->stmt_list
= NULL
;
1093 /* Walk the function tree removing unnecessary statements.
1095 * Empty statement nodes are removed
1097 * Unnecessary TRY_FINALLY and TRY_CATCH blocks are removed
1099 * Unnecessary COND_EXPRs are removed
1101 * Some unnecessary BIND_EXPRs are removed
1103 Clearly more work could be done. The trick is doing the analysis
1104 and removal fast enough to be a net improvement in compile times.
1106 Note that when we remove a control structure such as a COND_EXPR
1107 BIND_EXPR, or TRY block, we will need to repeat this optimization pass
1108 to ensure we eliminate all the useless code. */
1119 static void remove_useless_stmts_1 (tree
*, struct rus_data
*);
1122 remove_useless_stmts_warn_notreached (tree stmt
)
1124 if (EXPR_HAS_LOCATION (stmt
))
1126 location_t loc
= EXPR_LOCATION (stmt
);
1127 warning ("%Hwill never be executed", &loc
);
1131 switch (TREE_CODE (stmt
))
1133 case STATEMENT_LIST
:
1135 tree_stmt_iterator i
;
1136 for (i
= tsi_start (stmt
); !tsi_end_p (i
); tsi_next (&i
))
1137 if (remove_useless_stmts_warn_notreached (tsi_stmt (i
)))
1143 if (remove_useless_stmts_warn_notreached (COND_EXPR_COND (stmt
)))
1145 if (remove_useless_stmts_warn_notreached (COND_EXPR_THEN (stmt
)))
1147 if (remove_useless_stmts_warn_notreached (COND_EXPR_ELSE (stmt
)))
1151 case TRY_FINALLY_EXPR
:
1152 case TRY_CATCH_EXPR
:
1153 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt
, 0)))
1155 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt
, 1)))
1160 return remove_useless_stmts_warn_notreached (CATCH_BODY (stmt
));
1161 case EH_FILTER_EXPR
:
1162 return remove_useless_stmts_warn_notreached (EH_FILTER_FAILURE (stmt
));
1164 return remove_useless_stmts_warn_notreached (BIND_EXPR_BLOCK (stmt
));
1167 /* Not a live container. */
1175 remove_useless_stmts_cond (tree
*stmt_p
, struct rus_data
*data
)
1177 tree then_clause
, else_clause
, cond
;
1178 bool save_has_label
, then_has_label
, else_has_label
;
1180 save_has_label
= data
->has_label
;
1181 data
->has_label
= false;
1182 data
->last_goto
= NULL
;
1184 remove_useless_stmts_1 (&COND_EXPR_THEN (*stmt_p
), data
);
1186 then_has_label
= data
->has_label
;
1187 data
->has_label
= false;
1188 data
->last_goto
= NULL
;
1190 remove_useless_stmts_1 (&COND_EXPR_ELSE (*stmt_p
), data
);
1192 else_has_label
= data
->has_label
;
1193 data
->has_label
= save_has_label
| then_has_label
| else_has_label
;
1196 then_clause
= COND_EXPR_THEN (*stmt_p
);
1197 else_clause
= COND_EXPR_ELSE (*stmt_p
);
1198 cond
= COND_EXPR_COND (*stmt_p
);
1200 /* If neither arm does anything at all, we can remove the whole IF. */
1201 if (!TREE_SIDE_EFFECTS (then_clause
) && !TREE_SIDE_EFFECTS (else_clause
))
1203 *stmt_p
= build_empty_stmt ();
1204 data
->repeat
= true;
1207 /* If there are no reachable statements in an arm, then we can
1208 zap the entire conditional. */
1209 else if (integer_nonzerop (cond
) && !else_has_label
)
1211 if (warn_notreached
)
1212 remove_useless_stmts_warn_notreached (else_clause
);
1213 *stmt_p
= then_clause
;
1214 data
->repeat
= true;
1216 else if (integer_zerop (cond
) && !then_has_label
)
1218 if (warn_notreached
)
1219 remove_useless_stmts_warn_notreached (then_clause
);
1220 *stmt_p
= else_clause
;
1221 data
->repeat
= true;
1224 /* Check a couple of simple things on then/else with single stmts. */
1227 tree then_stmt
= expr_only (then_clause
);
1228 tree else_stmt
= expr_only (else_clause
);
1230 /* Notice branches to a common destination. */
1231 if (then_stmt
&& else_stmt
1232 && TREE_CODE (then_stmt
) == GOTO_EXPR
1233 && TREE_CODE (else_stmt
) == GOTO_EXPR
1234 && (GOTO_DESTINATION (then_stmt
) == GOTO_DESTINATION (else_stmt
)))
1236 *stmt_p
= then_stmt
;
1237 data
->repeat
= true;
1240 /* If the THEN/ELSE clause merely assigns a value to a variable or
1241 parameter which is already known to contain that value, then
1242 remove the useless THEN/ELSE clause. */
1243 else if (TREE_CODE (cond
) == VAR_DECL
|| TREE_CODE (cond
) == PARM_DECL
)
1246 && TREE_CODE (else_stmt
) == MODIFY_EXPR
1247 && TREE_OPERAND (else_stmt
, 0) == cond
1248 && integer_zerop (TREE_OPERAND (else_stmt
, 1)))
1249 COND_EXPR_ELSE (*stmt_p
) = alloc_stmt_list ();
1251 else if ((TREE_CODE (cond
) == EQ_EXPR
|| TREE_CODE (cond
) == NE_EXPR
)
1252 && (TREE_CODE (TREE_OPERAND (cond
, 0)) == VAR_DECL
1253 || TREE_CODE (TREE_OPERAND (cond
, 0)) == PARM_DECL
)
1254 && TREE_CONSTANT (TREE_OPERAND (cond
, 1)))
1256 tree stmt
= (TREE_CODE (cond
) == EQ_EXPR
1257 ? then_stmt
: else_stmt
);
1258 tree
*location
= (TREE_CODE (cond
) == EQ_EXPR
1259 ? &COND_EXPR_THEN (*stmt_p
)
1260 : &COND_EXPR_ELSE (*stmt_p
));
1263 && TREE_CODE (stmt
) == MODIFY_EXPR
1264 && TREE_OPERAND (stmt
, 0) == TREE_OPERAND (cond
, 0)
1265 && TREE_OPERAND (stmt
, 1) == TREE_OPERAND (cond
, 1))
1266 *location
= alloc_stmt_list ();
1270 /* Protect GOTOs in the arm of COND_EXPRs from being removed. They
1271 would be re-introduced during lowering. */
1272 data
->last_goto
= NULL
;
1277 remove_useless_stmts_tf (tree
*stmt_p
, struct rus_data
*data
)
1279 bool save_may_branch
, save_may_throw
;
1280 bool this_may_branch
, this_may_throw
;
1282 /* Collect may_branch and may_throw information for the body only. */
1283 save_may_branch
= data
->may_branch
;
1284 save_may_throw
= data
->may_throw
;
1285 data
->may_branch
= false;
1286 data
->may_throw
= false;
1287 data
->last_goto
= NULL
;
1289 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p
, 0), data
);
1291 this_may_branch
= data
->may_branch
;
1292 this_may_throw
= data
->may_throw
;
1293 data
->may_branch
|= save_may_branch
;
1294 data
->may_throw
|= save_may_throw
;
1295 data
->last_goto
= NULL
;
1297 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p
, 1), data
);
1299 /* If the body is empty, then we can emit the FINALLY block without
1300 the enclosing TRY_FINALLY_EXPR. */
1301 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p
, 0)))
1303 *stmt_p
= TREE_OPERAND (*stmt_p
, 1);
1304 data
->repeat
= true;
1307 /* If the handler is empty, then we can emit the TRY block without
1308 the enclosing TRY_FINALLY_EXPR. */
1309 else if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p
, 1)))
1311 *stmt_p
= TREE_OPERAND (*stmt_p
, 0);
1312 data
->repeat
= true;
1315 /* If the body neither throws, nor branches, then we can safely
1316 string the TRY and FINALLY blocks together. */
1317 else if (!this_may_branch
&& !this_may_throw
)
1319 tree stmt
= *stmt_p
;
1320 *stmt_p
= TREE_OPERAND (stmt
, 0);
1321 append_to_statement_list (TREE_OPERAND (stmt
, 1), stmt_p
);
1322 data
->repeat
= true;
1328 remove_useless_stmts_tc (tree
*stmt_p
, struct rus_data
*data
)
1330 bool save_may_throw
, this_may_throw
;
1331 tree_stmt_iterator i
;
1334 /* Collect may_throw information for the body only. */
1335 save_may_throw
= data
->may_throw
;
1336 data
->may_throw
= false;
1337 data
->last_goto
= NULL
;
1339 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p
, 0), data
);
1341 this_may_throw
= data
->may_throw
;
1342 data
->may_throw
= save_may_throw
;
1344 /* If the body cannot throw, then we can drop the entire TRY_CATCH_EXPR. */
1345 if (!this_may_throw
)
1347 if (warn_notreached
)
1348 remove_useless_stmts_warn_notreached (TREE_OPERAND (*stmt_p
, 1));
1349 *stmt_p
= TREE_OPERAND (*stmt_p
, 0);
1350 data
->repeat
= true;
1354 /* Process the catch clause specially. We may be able to tell that
1355 no exceptions propagate past this point. */
1357 this_may_throw
= true;
1358 i
= tsi_start (TREE_OPERAND (*stmt_p
, 1));
1359 stmt
= tsi_stmt (i
);
1360 data
->last_goto
= NULL
;
1362 switch (TREE_CODE (stmt
))
1365 for (; !tsi_end_p (i
); tsi_next (&i
))
1367 stmt
= tsi_stmt (i
);
1368 /* If we catch all exceptions, then the body does not
1369 propagate exceptions past this point. */
1370 if (CATCH_TYPES (stmt
) == NULL
)
1371 this_may_throw
= false;
1372 data
->last_goto
= NULL
;
1373 remove_useless_stmts_1 (&CATCH_BODY (stmt
), data
);
1377 case EH_FILTER_EXPR
:
1378 if (EH_FILTER_MUST_NOT_THROW (stmt
))
1379 this_may_throw
= false;
1380 else if (EH_FILTER_TYPES (stmt
) == NULL
)
1381 this_may_throw
= false;
1382 remove_useless_stmts_1 (&EH_FILTER_FAILURE (stmt
), data
);
1386 /* Otherwise this is a cleanup. */
1387 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p
, 1), data
);
1389 /* If the cleanup is empty, then we can emit the TRY block without
1390 the enclosing TRY_CATCH_EXPR. */
1391 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p
, 1)))
1393 *stmt_p
= TREE_OPERAND (*stmt_p
, 0);
1394 data
->repeat
= true;
1398 data
->may_throw
|= this_may_throw
;
1403 remove_useless_stmts_bind (tree
*stmt_p
, struct rus_data
*data
)
1407 /* First remove anything underneath the BIND_EXPR. */
1408 remove_useless_stmts_1 (&BIND_EXPR_BODY (*stmt_p
), data
);
1410 /* If the BIND_EXPR has no variables, then we can pull everything
1411 up one level and remove the BIND_EXPR, unless this is the toplevel
1412 BIND_EXPR for the current function or an inlined function.
1414 When this situation occurs we will want to apply this
1415 optimization again. */
1416 block
= BIND_EXPR_BLOCK (*stmt_p
);
1417 if (BIND_EXPR_VARS (*stmt_p
) == NULL_TREE
1418 && *stmt_p
!= DECL_SAVED_TREE (current_function_decl
)
1420 || ! BLOCK_ABSTRACT_ORIGIN (block
)
1421 || (TREE_CODE (BLOCK_ABSTRACT_ORIGIN (block
))
1424 *stmt_p
= BIND_EXPR_BODY (*stmt_p
);
1425 data
->repeat
= true;
1431 remove_useless_stmts_goto (tree
*stmt_p
, struct rus_data
*data
)
1433 tree dest
= GOTO_DESTINATION (*stmt_p
);
1435 data
->may_branch
= true;
1436 data
->last_goto
= NULL
;
1438 /* Record the last goto expr, so that we can delete it if unnecessary. */
1439 if (TREE_CODE (dest
) == LABEL_DECL
)
1440 data
->last_goto
= stmt_p
;
1445 remove_useless_stmts_label (tree
*stmt_p
, struct rus_data
*data
)
1447 tree label
= LABEL_EXPR_LABEL (*stmt_p
);
1449 data
->has_label
= true;
1451 /* We do want to jump across non-local label receiver code. */
1452 if (DECL_NONLOCAL (label
))
1453 data
->last_goto
= NULL
;
1455 else if (data
->last_goto
&& GOTO_DESTINATION (*data
->last_goto
) == label
)
1457 *data
->last_goto
= build_empty_stmt ();
1458 data
->repeat
= true;
1461 /* ??? Add something here to delete unused labels. */
1465 /* If the function is "const" or "pure", then clear TREE_SIDE_EFFECTS on its
1466 decl. This allows us to eliminate redundant or useless
1467 calls to "const" functions.
1469 Gimplifier already does the same operation, but we may notice functions
1470 being const and pure once their calls has been gimplified, so we need
1471 to update the flag. */
1474 update_call_expr_flags (tree call
)
1476 tree decl
= get_callee_fndecl (call
);
1479 if (call_expr_flags (call
) & (ECF_CONST
| ECF_PURE
))
1480 TREE_SIDE_EFFECTS (call
) = 0;
1481 if (TREE_NOTHROW (decl
))
1482 TREE_NOTHROW (call
) = 1;
1486 /* T is CALL_EXPR. Set current_function_calls_* flags. */
1489 notice_special_calls (tree t
)
1491 int flags
= call_expr_flags (t
);
1493 if (flags
& ECF_MAY_BE_ALLOCA
)
1494 current_function_calls_alloca
= true;
1495 if (flags
& ECF_RETURNS_TWICE
)
1496 current_function_calls_setjmp
= true;
1500 /* Clear flags set by notice_special_calls. Used by dead code removal
1501 to update the flags. */
1504 clear_special_calls (void)
1506 current_function_calls_alloca
= false;
1507 current_function_calls_setjmp
= false;
1512 remove_useless_stmts_1 (tree
*tp
, struct rus_data
*data
)
1516 switch (TREE_CODE (t
))
1519 remove_useless_stmts_cond (tp
, data
);
1522 case TRY_FINALLY_EXPR
:
1523 remove_useless_stmts_tf (tp
, data
);
1526 case TRY_CATCH_EXPR
:
1527 remove_useless_stmts_tc (tp
, data
);
1531 remove_useless_stmts_bind (tp
, data
);
1535 remove_useless_stmts_goto (tp
, data
);
1539 remove_useless_stmts_label (tp
, data
);
1544 data
->last_goto
= NULL
;
1545 data
->may_branch
= true;
1550 data
->last_goto
= NULL
;
1551 notice_special_calls (t
);
1552 update_call_expr_flags (t
);
1553 if (tree_could_throw_p (t
))
1554 data
->may_throw
= true;
1558 data
->last_goto
= NULL
;
1560 op
= get_call_expr_in (t
);
1563 update_call_expr_flags (op
);
1564 notice_special_calls (op
);
1566 if (tree_could_throw_p (t
))
1567 data
->may_throw
= true;
1570 case STATEMENT_LIST
:
1572 tree_stmt_iterator i
= tsi_start (t
);
1573 while (!tsi_end_p (i
))
1576 if (IS_EMPTY_STMT (t
))
1582 remove_useless_stmts_1 (tsi_stmt_ptr (i
), data
);
1585 if (TREE_CODE (t
) == STATEMENT_LIST
)
1587 tsi_link_before (&i
, t
, TSI_SAME_STMT
);
1597 data
->last_goto
= NULL
;
1601 data
->last_goto
= NULL
;
1607 remove_useless_stmts (void)
1609 struct rus_data data
;
1611 clear_special_calls ();
1615 memset (&data
, 0, sizeof (data
));
1616 remove_useless_stmts_1 (&DECL_SAVED_TREE (current_function_decl
), &data
);
1618 while (data
.repeat
);
1622 struct tree_opt_pass pass_remove_useless_stmts
=
1624 "useless", /* name */
1626 remove_useless_stmts
, /* execute */
1629 0, /* static_pass_number */
1631 PROP_gimple_any
, /* properties_required */
1632 0, /* properties_provided */
1633 0, /* properties_destroyed */
1634 0, /* todo_flags_start */
1635 TODO_dump_func
, /* todo_flags_finish */
1640 /* Remove obviously useless statements in basic block BB. */
1643 cfg_remove_useless_stmts_bb (basic_block bb
)
1645 block_stmt_iterator bsi
;
1646 tree stmt
= NULL_TREE
;
1647 tree cond
, var
= NULL_TREE
, val
= NULL_TREE
;
1648 struct var_ann_d
*ann
;
1650 /* Check whether we come here from a condition, and if so, get the
1653 || bb
->pred
->pred_next
1654 || !(bb
->pred
->flags
& (EDGE_TRUE_VALUE
| EDGE_FALSE_VALUE
)))
1657 cond
= COND_EXPR_COND (last_stmt (bb
->pred
->src
));
1659 if (TREE_CODE (cond
) == VAR_DECL
|| TREE_CODE (cond
) == PARM_DECL
)
1662 val
= (bb
->pred
->flags
& EDGE_FALSE_VALUE
1663 ? boolean_false_node
: boolean_true_node
);
1665 else if (TREE_CODE (cond
) == TRUTH_NOT_EXPR
1666 && (TREE_CODE (TREE_OPERAND (cond
, 0)) == VAR_DECL
1667 || TREE_CODE (TREE_OPERAND (cond
, 0)) == PARM_DECL
))
1669 var
= TREE_OPERAND (cond
, 0);
1670 val
= (bb
->pred
->flags
& EDGE_FALSE_VALUE
1671 ? boolean_true_node
: boolean_false_node
);
1675 if (bb
->pred
->flags
& EDGE_FALSE_VALUE
)
1676 cond
= invert_truthvalue (cond
);
1677 if (TREE_CODE (cond
) == EQ_EXPR
1678 && (TREE_CODE (TREE_OPERAND (cond
, 0)) == VAR_DECL
1679 || TREE_CODE (TREE_OPERAND (cond
, 0)) == PARM_DECL
)
1680 && (TREE_CODE (TREE_OPERAND (cond
, 1)) == VAR_DECL
1681 || TREE_CODE (TREE_OPERAND (cond
, 1)) == PARM_DECL
1682 || TREE_CONSTANT (TREE_OPERAND (cond
, 1))))
1684 var
= TREE_OPERAND (cond
, 0);
1685 val
= TREE_OPERAND (cond
, 1);
1691 /* Only work for normal local variables. */
1692 ann
= var_ann (var
);
1695 || TREE_ADDRESSABLE (var
))
1698 if (! TREE_CONSTANT (val
))
1700 ann
= var_ann (val
);
1703 || TREE_ADDRESSABLE (val
))
1707 /* Ignore floating point variables, since comparison behaves weird for
1709 if (FLOAT_TYPE_P (TREE_TYPE (var
)))
1712 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
);)
1714 stmt
= bsi_stmt (bsi
);
1716 /* If the THEN/ELSE clause merely assigns a value to a variable/parameter
1717 which is already known to contain that value, then remove the useless
1718 THEN/ELSE clause. */
1719 if (TREE_CODE (stmt
) == MODIFY_EXPR
1720 && TREE_OPERAND (stmt
, 0) == var
1721 && operand_equal_p (val
, TREE_OPERAND (stmt
, 1), 0))
1727 /* Invalidate the var if we encounter something that could modify it.
1728 Likewise for the value it was previously set to. Note that we only
1729 consider values that are either a VAR_DECL or PARM_DECL so we
1730 can test for conflict very simply. */
1731 if (TREE_CODE (stmt
) == ASM_EXPR
1732 || (TREE_CODE (stmt
) == MODIFY_EXPR
1733 && (TREE_OPERAND (stmt
, 0) == var
1734 || TREE_OPERAND (stmt
, 0) == val
)))
1742 /* A CFG-aware version of remove_useless_stmts. */
1745 cfg_remove_useless_stmts (void)
1749 #ifdef ENABLE_CHECKING
1750 verify_flow_info ();
1755 cfg_remove_useless_stmts_bb (bb
);
1760 /* Remove PHI nodes associated with basic block BB and all edges out of BB. */
1763 remove_phi_nodes_and_edges_for_unreachable_block (basic_block bb
)
1767 /* Since this block is no longer reachable, we can just delete all
1768 of its PHI nodes. */
1769 phi
= phi_nodes (bb
);
1772 tree next
= PHI_CHAIN (phi
);
1773 remove_phi_node (phi
, NULL_TREE
, bb
);
1777 /* Remove edges to BB's successors. */
1778 while (bb
->succ
!= NULL
)
1779 ssa_remove_edge (bb
->succ
);
1783 /* Remove statements of basic block BB. */
1786 remove_bb (basic_block bb
)
1788 block_stmt_iterator i
;
1789 source_locus loc
= 0;
1793 fprintf (dump_file
, "Removing basic block %d\n", bb
->index
);
1794 if (dump_flags
& TDF_DETAILS
)
1796 dump_bb (bb
, dump_file
, 0);
1797 fprintf (dump_file
, "\n");
1801 /* Remove all the instructions in the block. */
1802 for (i
= bsi_start (bb
); !bsi_end_p (i
); bsi_remove (&i
))
1804 tree stmt
= bsi_stmt (i
);
1806 set_bb_for_stmt (stmt
, NULL
);
1808 /* Don't warn for removed gotos. Gotos are often removed due to
1809 jump threading, thus resulting in bogus warnings. Not great,
1810 since this way we lose warnings for gotos in the original
1811 program that are indeed unreachable. */
1812 if (TREE_CODE (stmt
) != GOTO_EXPR
&& EXPR_HAS_LOCATION (stmt
) && !loc
)
1813 #ifdef USE_MAPPED_LOCATION
1814 loc
= EXPR_LOCATION (stmt
);
1816 loc
= EXPR_LOCUS (stmt
);
1820 /* If requested, give a warning that the first statement in the
1821 block is unreachable. We walk statements backwards in the
1822 loop above, so the last statement we process is the first statement
1824 if (warn_notreached
&& loc
)
1825 #ifdef USE_MAPPED_LOCATION
1826 warning ("%Hwill never be executed", &loc
);
1828 warning ("%Hwill never be executed", loc
);
1831 remove_phi_nodes_and_edges_for_unreachable_block (bb
);
1835 /* Examine BB to determine if it is a forwarding block (a block which only
1836 transfers control to a new destination). If BB is a forwarding block,
1837 then return the edge leading to the ultimate destination. */
1840 tree_block_forwards_to (basic_block bb
)
1842 block_stmt_iterator bsi
;
1843 bb_ann_t ann
= bb_ann (bb
);
1846 /* If this block is not forwardable, then avoid useless work. */
1847 if (! ann
->forwardable
)
1850 /* Set this block to not be forwardable. This prevents infinite loops since
1851 any block currently under examination is considered non-forwardable. */
1852 ann
->forwardable
= 0;
1854 /* No forwarding is possible if this block is a special block (ENTRY/EXIT),
1855 this block has more than one successor, this block's single successor is
1856 reached via an abnormal edge, this block has phi nodes, or this block's
1857 single successor has phi nodes. */
1858 if (bb
== EXIT_BLOCK_PTR
1859 || bb
== ENTRY_BLOCK_PTR
1861 || bb
->succ
->succ_next
1862 || bb
->succ
->dest
== EXIT_BLOCK_PTR
1863 || (bb
->succ
->flags
& EDGE_ABNORMAL
) != 0
1865 || phi_nodes (bb
->succ
->dest
))
1868 /* Walk past any labels at the start of this block. */
1869 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
1871 stmt
= bsi_stmt (bsi
);
1872 if (TREE_CODE (stmt
) != LABEL_EXPR
)
1876 /* If we reached the end of this block we may be able to optimize this
1878 if (bsi_end_p (bsi
))
1882 /* Recursive call to pick up chains of forwarding blocks. */
1883 dest
= tree_block_forwards_to (bb
->succ
->dest
);
1885 /* If none found, we forward to bb->succ at minimum. */
1889 ann
->forwardable
= 1;
1893 /* No forwarding possible. */
1898 /* Try to remove superfluous control structures. */
1901 cleanup_control_flow (void)
1904 block_stmt_iterator bsi
;
1905 bool retval
= false;
1910 bsi
= bsi_last (bb
);
1912 if (bsi_end_p (bsi
))
1915 stmt
= bsi_stmt (bsi
);
1916 if (TREE_CODE (stmt
) == COND_EXPR
1917 || TREE_CODE (stmt
) == SWITCH_EXPR
)
1918 retval
|= cleanup_control_expr_graph (bb
, bsi
);
1924 /* Disconnect an unreachable block in the control expression starting
1928 cleanup_control_expr_graph (basic_block bb
, block_stmt_iterator bsi
)
1931 bool retval
= false;
1932 tree expr
= bsi_stmt (bsi
), val
;
1934 if (bb
->succ
->succ_next
)
1938 switch (TREE_CODE (expr
))
1941 val
= COND_EXPR_COND (expr
);
1945 val
= SWITCH_COND (expr
);
1946 if (TREE_CODE (val
) != INTEGER_CST
)
1954 taken_edge
= find_taken_edge (bb
, val
);
1958 /* Remove all the edges except the one that is always executed. */
1959 for (e
= bb
->succ
; e
; e
= next
)
1961 next
= e
->succ_next
;
1962 if (e
!= taken_edge
)
1964 taken_edge
->probability
+= e
->probability
;
1965 taken_edge
->count
+= e
->count
;
1966 ssa_remove_edge (e
);
1970 if (taken_edge
->probability
> REG_BR_PROB_BASE
)
1971 taken_edge
->probability
= REG_BR_PROB_BASE
;
1974 taken_edge
= bb
->succ
;
1977 taken_edge
->flags
= EDGE_FALLTHRU
;
1979 /* We removed some paths from the cfg. */
1980 if (dom_computed
[CDI_DOMINATORS
] >= DOM_CONS_OK
)
1981 dom_computed
[CDI_DOMINATORS
] = DOM_CONS_OK
;
1987 /* Given a control block BB and a predicate VAL, return the edge that
1988 will be taken out of the block. If VAL does not match a unique
1989 edge, NULL is returned. */
1992 find_taken_edge (basic_block bb
, tree val
)
1996 stmt
= last_stmt (bb
);
1999 gcc_assert (is_ctrl_stmt (stmt
));
2001 /* If VAL is a predicate of the form N RELOP N, where N is an
2002 SSA_NAME, we can always determine its truth value (except when
2003 doing floating point comparisons that may involve NaNs). */
2005 && TREE_CODE_CLASS (TREE_CODE (val
)) == '<'
2006 && TREE_OPERAND (val
, 0) == TREE_OPERAND (val
, 1)
2007 && TREE_CODE (TREE_OPERAND (val
, 0)) == SSA_NAME
2008 && (TREE_CODE (TREE_TYPE (TREE_OPERAND (val
, 0))) != REAL_TYPE
2009 || !HONOR_NANS (TYPE_MODE (TREE_TYPE (TREE_OPERAND (val
, 0))))))
2011 enum tree_code code
= TREE_CODE (val
);
2013 if (code
== EQ_EXPR
|| code
== LE_EXPR
|| code
== GE_EXPR
)
2014 val
= boolean_true_node
;
2015 else if (code
== LT_EXPR
|| code
== GT_EXPR
|| code
== NE_EXPR
)
2016 val
= boolean_false_node
;
2019 /* If VAL is not a constant, we can't determine which edge might
2021 if (val
== NULL
|| !really_constant_p (val
))
2024 if (TREE_CODE (stmt
) == COND_EXPR
)
2025 return find_taken_edge_cond_expr (bb
, val
);
2027 if (TREE_CODE (stmt
) == SWITCH_EXPR
)
2028 return find_taken_edge_switch_expr (bb
, val
);
2034 /* Given a constant value VAL and the entry block BB to a COND_EXPR
2035 statement, determine which of the two edges will be taken out of the
2036 block. Return NULL if either edge may be taken. */
2039 find_taken_edge_cond_expr (basic_block bb
, tree val
)
2041 edge true_edge
, false_edge
;
2043 extract_true_false_edges_from_block (bb
, &true_edge
, &false_edge
);
2045 /* If both edges of the branch lead to the same basic block, it doesn't
2046 matter which edge is taken. */
2047 if (true_edge
->dest
== false_edge
->dest
)
2050 /* Otherwise, try to determine which branch of the if() will be taken.
2051 If VAL is a constant but it can't be reduced to a 0 or a 1, then
2052 we don't really know which edge will be taken at runtime. This
2053 may happen when comparing addresses (e.g., if (&var1 == 4)). */
2054 if (integer_nonzerop (val
))
2056 else if (integer_zerop (val
))
2063 /* Given a constant value VAL and the entry block BB to a SWITCH_EXPR
2064 statement, determine which edge will be taken out of the block. Return
2065 NULL if any edge may be taken. */
2068 find_taken_edge_switch_expr (basic_block bb
, tree val
)
2070 tree switch_expr
, taken_case
;
2071 basic_block dest_bb
;
2074 if (TREE_CODE (val
) != INTEGER_CST
)
2077 switch_expr
= last_stmt (bb
);
2078 taken_case
= find_case_label_for_value (switch_expr
, val
);
2079 dest_bb
= label_to_block (CASE_LABEL (taken_case
));
2081 e
= find_edge (bb
, dest_bb
);
2087 /* Return the CASE_LABEL_EXPR that SWITCH_EXPR will take for VAL.
2088 We can make optimal use here of the fact that the case labels are
2089 sorted: We can do a binary search for a case matching VAL. */
2092 find_case_label_for_value (tree switch_expr
, tree val
)
2094 tree vec
= SWITCH_LABELS (switch_expr
);
2095 size_t low
, high
, n
= TREE_VEC_LENGTH (vec
);
2096 tree default_case
= TREE_VEC_ELT (vec
, n
- 1);
2098 for (low
= -1, high
= n
- 1; high
- low
> 1; )
2100 size_t i
= (high
+ low
) / 2;
2101 tree t
= TREE_VEC_ELT (vec
, i
);
2104 /* Cache the result of comparing CASE_LOW and val. */
2105 cmp
= tree_int_cst_compare (CASE_LOW (t
), val
);
2112 if (CASE_HIGH (t
) == NULL
)
2114 /* A singe-valued case label. */
2120 /* A case range. We can only handle integer ranges. */
2121 if (cmp
<= 0 && tree_int_cst_compare (CASE_HIGH (t
), val
) >= 0)
2126 return default_case
;
2130 /* If all the PHI nodes in DEST have alternatives for E1 and E2 and
2131 those alternatives are equal in each of the PHI nodes, then return
2132 true, else return false. */
2135 phi_alternatives_equal (basic_block dest
, edge e1
, edge e2
)
2137 tree phi
, val1
, val2
;
2140 for (phi
= phi_nodes (dest
); phi
; phi
= PHI_CHAIN (phi
))
2142 n1
= phi_arg_from_edge (phi
, e1
);
2143 n2
= phi_arg_from_edge (phi
, e2
);
2145 gcc_assert (n1
>= 0);
2146 gcc_assert (n2
>= 0);
2148 val1
= PHI_ARG_DEF (phi
, n1
);
2149 val2
= PHI_ARG_DEF (phi
, n2
);
2151 if (!operand_equal_p (val1
, val2
, 0))
2159 /*---------------------------------------------------------------------------
2161 ---------------------------------------------------------------------------*/
2163 /* Dump tree-specific information of block BB to file OUTF. */
2166 tree_dump_bb (basic_block bb
, FILE *outf
, int indent
)
2168 dump_generic_bb (outf
, bb
, indent
, TDF_VOPS
);
2172 /* Dump a basic block on stderr. */
2175 debug_tree_bb (basic_block bb
)
2177 dump_bb (bb
, stderr
, 0);
2181 /* Dump basic block with index N on stderr. */
2184 debug_tree_bb_n (int n
)
2186 debug_tree_bb (BASIC_BLOCK (n
));
2187 return BASIC_BLOCK (n
);
2191 /* Dump the CFG on stderr.
2193 FLAGS are the same used by the tree dumping functions
2194 (see TDF_* in tree.h). */
2197 debug_tree_cfg (int flags
)
2199 dump_tree_cfg (stderr
, flags
);
2203 /* Dump the program showing basic block boundaries on the given FILE.
2205 FLAGS are the same used by the tree dumping functions (see TDF_* in
2209 dump_tree_cfg (FILE *file
, int flags
)
2211 if (flags
& TDF_DETAILS
)
2213 const char *funcname
2214 = lang_hooks
.decl_printable_name (current_function_decl
, 2);
2217 fprintf (file
, ";; Function %s\n\n", funcname
);
2218 fprintf (file
, ";; \n%d basic blocks, %d edges, last basic block %d.\n\n",
2219 n_basic_blocks
, n_edges
, last_basic_block
);
2221 brief_dump_cfg (file
);
2222 fprintf (file
, "\n");
2225 if (flags
& TDF_STATS
)
2226 dump_cfg_stats (file
);
2228 dump_function_to_file (current_function_decl
, file
, flags
| TDF_BLOCKS
);
2232 /* Dump CFG statistics on FILE. */
2235 dump_cfg_stats (FILE *file
)
2237 static long max_num_merged_labels
= 0;
2238 unsigned long size
, total
= 0;
2241 const char * const fmt_str
= "%-30s%-13s%12s\n";
2242 const char * const fmt_str_1
= "%-30s%13d%11lu%c\n";
2243 const char * const fmt_str_3
= "%-43s%11lu%c\n";
2244 const char *funcname
2245 = lang_hooks
.decl_printable_name (current_function_decl
, 2);
2248 fprintf (file
, "\nCFG Statistics for %s\n\n", funcname
);
2250 fprintf (file
, "---------------------------------------------------------\n");
2251 fprintf (file
, fmt_str
, "", " Number of ", "Memory");
2252 fprintf (file
, fmt_str
, "", " instances ", "used ");
2253 fprintf (file
, "---------------------------------------------------------\n");
2255 size
= n_basic_blocks
* sizeof (struct basic_block_def
);
2257 fprintf (file
, fmt_str_1
, "Basic blocks", n_basic_blocks
,
2258 SCALE (size
), LABEL (size
));
2264 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
2267 size
= n_edges
* sizeof (struct edge_def
);
2269 fprintf (file
, fmt_str_1
, "Edges", n_edges
, SCALE (size
), LABEL (size
));
2271 size
= n_basic_blocks
* sizeof (struct bb_ann_d
);
2273 fprintf (file
, fmt_str_1
, "Basic block annotations", n_basic_blocks
,
2274 SCALE (size
), LABEL (size
));
2276 fprintf (file
, "---------------------------------------------------------\n");
2277 fprintf (file
, fmt_str_3
, "Total memory used by CFG data", SCALE (total
),
2279 fprintf (file
, "---------------------------------------------------------\n");
2280 fprintf (file
, "\n");
2282 if (cfg_stats
.num_merged_labels
> max_num_merged_labels
)
2283 max_num_merged_labels
= cfg_stats
.num_merged_labels
;
2285 fprintf (file
, "Coalesced label blocks: %ld (Max so far: %ld)\n",
2286 cfg_stats
.num_merged_labels
, max_num_merged_labels
);
2288 fprintf (file
, "\n");
2292 /* Dump CFG statistics on stderr. Keep extern so that it's always
2293 linked in the final executable. */
2296 debug_cfg_stats (void)
2298 dump_cfg_stats (stderr
);
2302 /* Dump the flowgraph to a .vcg FILE. */
2305 tree_cfg2vcg (FILE *file
)
2309 const char *funcname
2310 = lang_hooks
.decl_printable_name (current_function_decl
, 2);
2312 /* Write the file header. */
2313 fprintf (file
, "graph: { title: \"%s\"\n", funcname
);
2314 fprintf (file
, "node: { title: \"ENTRY\" label: \"ENTRY\" }\n");
2315 fprintf (file
, "node: { title: \"EXIT\" label: \"EXIT\" }\n");
2317 /* Write blocks and edges. */
2318 for (e
= ENTRY_BLOCK_PTR
->succ
; e
; e
= e
->succ_next
)
2320 fprintf (file
, "edge: { sourcename: \"ENTRY\" targetname: \"%d\"",
2323 if (e
->flags
& EDGE_FAKE
)
2324 fprintf (file
, " linestyle: dotted priority: 10");
2326 fprintf (file
, " linestyle: solid priority: 100");
2328 fprintf (file
, " }\n");
2334 enum tree_code head_code
, end_code
;
2335 const char *head_name
, *end_name
;
2338 tree first
= first_stmt (bb
);
2339 tree last
= last_stmt (bb
);
2343 head_code
= TREE_CODE (first
);
2344 head_name
= tree_code_name
[head_code
];
2345 head_line
= get_lineno (first
);
2348 head_name
= "no-statement";
2352 end_code
= TREE_CODE (last
);
2353 end_name
= tree_code_name
[end_code
];
2354 end_line
= get_lineno (last
);
2357 end_name
= "no-statement";
2359 fprintf (file
, "node: { title: \"%d\" label: \"#%d\\n%s (%d)\\n%s (%d)\"}\n",
2360 bb
->index
, bb
->index
, head_name
, head_line
, end_name
,
2363 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
2365 if (e
->dest
== EXIT_BLOCK_PTR
)
2366 fprintf (file
, "edge: { sourcename: \"%d\" targetname: \"EXIT\"", bb
->index
);
2368 fprintf (file
, "edge: { sourcename: \"%d\" targetname: \"%d\"", bb
->index
, e
->dest
->index
);
2370 if (e
->flags
& EDGE_FAKE
)
2371 fprintf (file
, " priority: 10 linestyle: dotted");
2373 fprintf (file
, " priority: 100 linestyle: solid");
2375 fprintf (file
, " }\n");
2378 if (bb
->next_bb
!= EXIT_BLOCK_PTR
)
2382 fputs ("}\n\n", file
);
2387 /*---------------------------------------------------------------------------
2388 Miscellaneous helpers
2389 ---------------------------------------------------------------------------*/
2391 /* Return true if T represents a stmt that always transfers control. */
2394 is_ctrl_stmt (tree t
)
2396 return (TREE_CODE (t
) == COND_EXPR
2397 || TREE_CODE (t
) == SWITCH_EXPR
2398 || TREE_CODE (t
) == GOTO_EXPR
2399 || TREE_CODE (t
) == RETURN_EXPR
2400 || TREE_CODE (t
) == RESX_EXPR
);
2404 /* Return true if T is a statement that may alter the flow of control
2405 (e.g., a call to a non-returning function). */
2408 is_ctrl_altering_stmt (tree t
)
2413 call
= get_call_expr_in (t
);
2416 /* A non-pure/const CALL_EXPR alters flow control if the current
2417 function has nonlocal labels. */
2418 if (TREE_SIDE_EFFECTS (call
) && current_function_has_nonlocal_label
)
2421 /* A CALL_EXPR also alters control flow if it does not return. */
2422 if (call_expr_flags (call
) & (ECF_NORETURN
| ECF_LONGJMP
))
2426 /* If a statement can throw, it alters control flow. */
2427 return tree_can_throw_internal (t
);
2431 /* Return true if T is a computed goto. */
2434 computed_goto_p (tree t
)
2436 return (TREE_CODE (t
) == GOTO_EXPR
2437 && TREE_CODE (GOTO_DESTINATION (t
)) != LABEL_DECL
);
2441 /* Checks whether EXPR is a simple local goto. */
2444 simple_goto_p (tree expr
)
2446 return (TREE_CODE (expr
) == GOTO_EXPR
2447 && TREE_CODE (GOTO_DESTINATION (expr
)) == LABEL_DECL
);
2451 /* Return true if T should start a new basic block. PREV_T is the
2452 statement preceding T. It is used when T is a label or a case label.
2453 Labels should only start a new basic block if their previous statement
2454 wasn't a label. Otherwise, sequence of labels would generate
2455 unnecessary basic blocks that only contain a single label. */
2458 stmt_starts_bb_p (tree t
, tree prev_t
)
2460 enum tree_code code
;
2465 /* LABEL_EXPRs start a new basic block only if the preceding
2466 statement wasn't a label of the same type. This prevents the
2467 creation of consecutive blocks that have nothing but a single
2469 code
= TREE_CODE (t
);
2470 if (code
== LABEL_EXPR
)
2472 /* Nonlocal and computed GOTO targets always start a new block. */
2473 if (code
== LABEL_EXPR
2474 && (DECL_NONLOCAL (LABEL_EXPR_LABEL (t
))
2475 || FORCED_LABEL (LABEL_EXPR_LABEL (t
))))
2478 if (prev_t
&& TREE_CODE (prev_t
) == code
)
2480 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (prev_t
)))
2483 cfg_stats
.num_merged_labels
++;
2494 /* Return true if T should end a basic block. */
2497 stmt_ends_bb_p (tree t
)
2499 return is_ctrl_stmt (t
) || is_ctrl_altering_stmt (t
);
2503 /* Add gotos that used to be represented implicitly in the CFG. */
2506 disband_implicit_edges (void)
2509 block_stmt_iterator last
;
2515 last
= bsi_last (bb
);
2516 stmt
= last_stmt (bb
);
2518 if (stmt
&& TREE_CODE (stmt
) == COND_EXPR
)
2520 /* Remove superfluous gotos from COND_EXPR branches. Moved
2521 from cfg_remove_useless_stmts here since it violates the
2522 invariants for tree--cfg correspondence and thus fits better
2523 here where we do it anyway. */
2524 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
2526 if (e
->dest
!= bb
->next_bb
)
2529 if (e
->flags
& EDGE_TRUE_VALUE
)
2530 COND_EXPR_THEN (stmt
) = build_empty_stmt ();
2531 else if (e
->flags
& EDGE_FALSE_VALUE
)
2532 COND_EXPR_ELSE (stmt
) = build_empty_stmt ();
2535 e
->flags
|= EDGE_FALLTHRU
;
2541 if (stmt
&& TREE_CODE (stmt
) == RETURN_EXPR
)
2543 /* Remove the RETURN_EXPR if we may fall though to the exit
2545 gcc_assert (bb
->succ
);
2546 gcc_assert (!bb
->succ
->succ_next
);
2547 gcc_assert (bb
->succ
->dest
== EXIT_BLOCK_PTR
);
2549 if (bb
->next_bb
== EXIT_BLOCK_PTR
2550 && !TREE_OPERAND (stmt
, 0))
2553 bb
->succ
->flags
|= EDGE_FALLTHRU
;
2558 /* There can be no fallthru edge if the last statement is a control
2560 if (stmt
&& is_ctrl_stmt (stmt
))
2563 /* Find a fallthru edge and emit the goto if necessary. */
2564 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
2565 if (e
->flags
& EDGE_FALLTHRU
)
2568 if (!e
|| e
->dest
== bb
->next_bb
)
2571 gcc_assert (e
->dest
!= EXIT_BLOCK_PTR
);
2572 label
= tree_block_label (e
->dest
);
2574 stmt
= build1 (GOTO_EXPR
, void_type_node
, label
);
2575 #ifdef USE_MAPPED_LOCATION
2576 SET_EXPR_LOCATION (stmt
, e
->goto_locus
);
2578 SET_EXPR_LOCUS (stmt
, e
->goto_locus
);
2580 bsi_insert_after (&last
, stmt
, BSI_NEW_STMT
);
2581 e
->flags
&= ~EDGE_FALLTHRU
;
2585 /* Remove block annotations and other datastructures. */
2588 delete_tree_cfg_annotations (void)
2591 if (n_basic_blocks
> 0)
2592 free_blocks_annotations ();
2594 label_to_block_map
= NULL
;
2601 /* Return the first statement in basic block BB. */
2604 first_stmt (basic_block bb
)
2606 block_stmt_iterator i
= bsi_start (bb
);
2607 return !bsi_end_p (i
) ? bsi_stmt (i
) : NULL_TREE
;
2611 /* Return the last statement in basic block BB. */
2614 last_stmt (basic_block bb
)
2616 block_stmt_iterator b
= bsi_last (bb
);
2617 return !bsi_end_p (b
) ? bsi_stmt (b
) : NULL_TREE
;
2621 /* Return a pointer to the last statement in block BB. */
2624 last_stmt_ptr (basic_block bb
)
2626 block_stmt_iterator last
= bsi_last (bb
);
2627 return !bsi_end_p (last
) ? bsi_stmt_ptr (last
) : NULL
;
2631 /* Return the last statement of an otherwise empty block. Return NULL
2632 if the block is totally empty, or if it contains more than one
2636 last_and_only_stmt (basic_block bb
)
2638 block_stmt_iterator i
= bsi_last (bb
);
2644 last
= bsi_stmt (i
);
2649 /* Empty statements should no longer appear in the instruction stream.
2650 Everything that might have appeared before should be deleted by
2651 remove_useless_stmts, and the optimizers should just bsi_remove
2652 instead of smashing with build_empty_stmt.
2654 Thus the only thing that should appear here in a block containing
2655 one executable statement is a label. */
2656 prev
= bsi_stmt (i
);
2657 if (TREE_CODE (prev
) == LABEL_EXPR
)
2664 /* Mark BB as the basic block holding statement T. */
2667 set_bb_for_stmt (tree t
, basic_block bb
)
2669 if (TREE_CODE (t
) == STATEMENT_LIST
)
2671 tree_stmt_iterator i
;
2672 for (i
= tsi_start (t
); !tsi_end_p (i
); tsi_next (&i
))
2673 set_bb_for_stmt (tsi_stmt (i
), bb
);
2677 stmt_ann_t ann
= get_stmt_ann (t
);
2680 /* If the statement is a label, add the label to block-to-labels map
2681 so that we can speed up edge creation for GOTO_EXPRs. */
2682 if (TREE_CODE (t
) == LABEL_EXPR
)
2686 t
= LABEL_EXPR_LABEL (t
);
2687 uid
= LABEL_DECL_UID (t
);
2690 LABEL_DECL_UID (t
) = uid
= cfun
->last_label_uid
++;
2691 if (VARRAY_SIZE (label_to_block_map
) <= (unsigned) uid
)
2692 VARRAY_GROW (label_to_block_map
, 3 * uid
/ 2);
2695 /* We're moving an existing label. Make sure that we've
2696 removed it from the old block. */
2697 gcc_assert (!bb
|| !VARRAY_BB (label_to_block_map
, uid
));
2698 VARRAY_BB (label_to_block_map
, uid
) = bb
;
2703 /* Finds iterator for STMT. */
2705 extern block_stmt_iterator
2706 stmt_for_bsi (tree stmt
)
2708 block_stmt_iterator bsi
;
2710 for (bsi
= bsi_start (bb_for_stmt (stmt
)); !bsi_end_p (bsi
); bsi_next (&bsi
))
2711 if (bsi_stmt (bsi
) == stmt
)
2717 /* Insert statement (or statement list) T before the statement
2718 pointed-to by iterator I. M specifies how to update iterator I
2719 after insertion (see enum bsi_iterator_update). */
2722 bsi_insert_before (block_stmt_iterator
*i
, tree t
, enum bsi_iterator_update m
)
2724 set_bb_for_stmt (t
, i
->bb
);
2725 tsi_link_before (&i
->tsi
, t
, m
);
2730 /* Insert statement (or statement list) T after the statement
2731 pointed-to by iterator I. M specifies how to update iterator I
2732 after insertion (see enum bsi_iterator_update). */
2735 bsi_insert_after (block_stmt_iterator
*i
, tree t
, enum bsi_iterator_update m
)
2737 set_bb_for_stmt (t
, i
->bb
);
2738 tsi_link_after (&i
->tsi
, t
, m
);
2743 /* Remove the statement pointed to by iterator I. The iterator is updated
2744 to the next statement. */
2747 bsi_remove (block_stmt_iterator
*i
)
2749 tree t
= bsi_stmt (*i
);
2750 set_bb_for_stmt (t
, NULL
);
2751 tsi_delink (&i
->tsi
);
2755 /* Move the statement at FROM so it comes right after the statement at TO. */
2758 bsi_move_after (block_stmt_iterator
*from
, block_stmt_iterator
*to
)
2760 tree stmt
= bsi_stmt (*from
);
2762 bsi_insert_after (to
, stmt
, BSI_SAME_STMT
);
2766 /* Move the statement at FROM so it comes right before the statement at TO. */
2769 bsi_move_before (block_stmt_iterator
*from
, block_stmt_iterator
*to
)
2771 tree stmt
= bsi_stmt (*from
);
2773 bsi_insert_before (to
, stmt
, BSI_SAME_STMT
);
2777 /* Move the statement at FROM to the end of basic block BB. */
2780 bsi_move_to_bb_end (block_stmt_iterator
*from
, basic_block bb
)
2782 block_stmt_iterator last
= bsi_last (bb
);
2784 /* Have to check bsi_end_p because it could be an empty block. */
2785 if (!bsi_end_p (last
) && is_ctrl_stmt (bsi_stmt (last
)))
2786 bsi_move_before (from
, &last
);
2788 bsi_move_after (from
, &last
);
2792 /* Replace the contents of the statement pointed to by iterator BSI
2793 with STMT. If PRESERVE_EH_INFO is true, the exception handling
2794 information of the original statement is preserved. */
2797 bsi_replace (const block_stmt_iterator
*bsi
, tree stmt
, bool preserve_eh_info
)
2800 tree orig_stmt
= bsi_stmt (*bsi
);
2802 SET_EXPR_LOCUS (stmt
, EXPR_LOCUS (orig_stmt
));
2803 set_bb_for_stmt (stmt
, bsi
->bb
);
2805 /* Preserve EH region information from the original statement, if
2806 requested by the caller. */
2807 if (preserve_eh_info
)
2809 eh_region
= lookup_stmt_eh_region (orig_stmt
);
2811 add_stmt_to_eh_region (stmt
, eh_region
);
2814 *bsi_stmt_ptr (*bsi
) = stmt
;
2819 /* Insert the statement pointed-to by BSI into edge E. Every attempt
2820 is made to place the statement in an existing basic block, but
2821 sometimes that isn't possible. When it isn't possible, the edge is
2822 split and the statement is added to the new block.
2824 In all cases, the returned *BSI points to the correct location. The
2825 return value is true if insertion should be done after the location,
2826 or false if it should be done before the location. If new basic block
2827 has to be created, it is stored in *NEW_BB. */
2830 tree_find_edge_insert_loc (edge e
, block_stmt_iterator
*bsi
,
2831 basic_block
*new_bb
)
2833 basic_block dest
, src
;
2839 /* If the destination has one predecessor which has no PHI nodes,
2840 insert there. Except for the exit block.
2842 The requirement for no PHI nodes could be relaxed. Basically we
2843 would have to examine the PHIs to prove that none of them used
2844 the value set by the statement we want to insert on E. That
2845 hardly seems worth the effort. */
2846 if (dest
->pred
->pred_next
== NULL
2847 && ! phi_nodes (dest
)
2848 && dest
!= EXIT_BLOCK_PTR
)
2850 *bsi
= bsi_start (dest
);
2851 if (bsi_end_p (*bsi
))
2854 /* Make sure we insert after any leading labels. */
2855 tmp
= bsi_stmt (*bsi
);
2856 while (TREE_CODE (tmp
) == LABEL_EXPR
)
2859 if (bsi_end_p (*bsi
))
2861 tmp
= bsi_stmt (*bsi
);
2864 if (bsi_end_p (*bsi
))
2866 *bsi
= bsi_last (dest
);
2873 /* If the source has one successor, the edge is not abnormal and
2874 the last statement does not end a basic block, insert there.
2875 Except for the entry block. */
2877 if ((e
->flags
& EDGE_ABNORMAL
) == 0
2878 && src
->succ
->succ_next
== NULL
2879 && src
!= ENTRY_BLOCK_PTR
)
2881 *bsi
= bsi_last (src
);
2882 if (bsi_end_p (*bsi
))
2885 tmp
= bsi_stmt (*bsi
);
2886 if (!stmt_ends_bb_p (tmp
))
2889 /* Insert code just before returning the value. We may need to decompose
2890 the return in the case it contains non-trivial operand. */
2891 if (TREE_CODE (tmp
) == RETURN_EXPR
)
2893 tree op
= TREE_OPERAND (tmp
, 0);
2894 if (!is_gimple_val (op
))
2896 gcc_assert (TREE_CODE (op
) == MODIFY_EXPR
);
2897 bsi_insert_before (bsi
, op
, BSI_NEW_STMT
);
2898 TREE_OPERAND (tmp
, 0) = TREE_OPERAND (op
, 0);
2905 /* Otherwise, create a new basic block, and split this edge. */
2906 dest
= split_edge (e
);
2914 /* This routine will commit all pending edge insertions, creating any new
2915 basic blocks which are necessary.
2917 If specified, NEW_BLOCKS returns a count of the number of new basic
2918 blocks which were created. */
2921 bsi_commit_edge_inserts (int *new_blocks
)
2927 blocks
= n_basic_blocks
;
2929 bsi_commit_edge_inserts_1 (ENTRY_BLOCK_PTR
->succ
);
2932 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
2933 bsi_commit_edge_inserts_1 (e
);
2936 *new_blocks
= n_basic_blocks
- blocks
;
2940 /* Commit insertions pending at edge E. */
2943 bsi_commit_edge_inserts_1 (edge e
)
2945 if (PENDING_STMT (e
))
2947 block_stmt_iterator bsi
;
2948 tree stmt
= PENDING_STMT (e
);
2950 PENDING_STMT (e
) = NULL_TREE
;
2952 if (tree_find_edge_insert_loc (e
, &bsi
, NULL
))
2953 bsi_insert_after (&bsi
, stmt
, BSI_NEW_STMT
);
2955 bsi_insert_before (&bsi
, stmt
, BSI_NEW_STMT
);
2960 /* Add STMT to the pending list of edge E. No actual insertion is
2961 made until a call to bsi_commit_edge_inserts () is made. */
2964 bsi_insert_on_edge (edge e
, tree stmt
)
2966 append_to_statement_list (stmt
, &PENDING_STMT (e
));
2969 /* Similar to bsi_insert_on_edge+bsi_commit_edge_inserts. If new block has to
2970 be created, it is returned. */
2973 bsi_insert_on_edge_immediate (edge e
, tree stmt
)
2975 block_stmt_iterator bsi
;
2976 basic_block new_bb
= NULL
;
2978 gcc_assert (!PENDING_STMT (e
));
2980 if (tree_find_edge_insert_loc (e
, &bsi
, &new_bb
))
2981 bsi_insert_after (&bsi
, stmt
, BSI_NEW_STMT
);
2983 bsi_insert_before (&bsi
, stmt
, BSI_NEW_STMT
);
2988 /*---------------------------------------------------------------------------
2989 Tree specific functions for CFG manipulation
2990 ---------------------------------------------------------------------------*/
2992 /* Split a (typically critical) edge EDGE_IN. Return the new block.
2993 Abort on abnormal edges. */
2996 tree_split_edge (edge edge_in
)
2998 basic_block new_bb
, after_bb
, dest
, src
;
3003 /* Abnormal edges cannot be split. */
3004 gcc_assert (!(edge_in
->flags
& EDGE_ABNORMAL
));
3007 dest
= edge_in
->dest
;
3009 /* Place the new block in the block list. Try to keep the new block
3010 near its "logical" location. This is of most help to humans looking
3011 at debugging dumps. */
3012 for (e
= dest
->pred
; e
; e
= e
->pred_next
)
3013 if (e
->src
->next_bb
== dest
)
3016 after_bb
= dest
->prev_bb
;
3018 after_bb
= edge_in
->src
;
3020 new_bb
= create_empty_bb (after_bb
);
3021 new_bb
->frequency
= EDGE_FREQUENCY (edge_in
);
3022 new_bb
->count
= edge_in
->count
;
3023 new_edge
= make_edge (new_bb
, dest
, EDGE_FALLTHRU
);
3024 new_edge
->probability
= REG_BR_PROB_BASE
;
3025 new_edge
->count
= edge_in
->count
;
3027 /* Find all the PHI arguments on the original edge, and change them to
3028 the new edge. Do it before redirection, so that the argument does not
3030 for (phi
= phi_nodes (dest
); phi
; phi
= PHI_CHAIN (phi
))
3032 num_elem
= PHI_NUM_ARGS (phi
);
3033 for (i
= 0; i
< num_elem
; i
++)
3034 if (PHI_ARG_EDGE (phi
, i
) == edge_in
)
3036 PHI_ARG_EDGE (phi
, i
) = new_edge
;
3041 e
= redirect_edge_and_branch (edge_in
, new_bb
);
3043 gcc_assert (!PENDING_STMT (edge_in
));
3049 /* Return true when BB has label LABEL in it. */
3052 has_label_p (basic_block bb
, tree label
)
3054 block_stmt_iterator bsi
;
3056 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
3058 tree stmt
= bsi_stmt (bsi
);
3060 if (TREE_CODE (stmt
) != LABEL_EXPR
)
3062 if (LABEL_EXPR_LABEL (stmt
) == label
)
3069 /* Callback for walk_tree, check that all elements with address taken are
3070 properly noticed as such. */
3073 verify_expr (tree
*tp
, int *walk_subtrees
, void *data ATTRIBUTE_UNUSED
)
3080 /* Check operand N for being valid GIMPLE and give error MSG if not.
3081 We check for constants explicitly since they are not considered
3082 gimple invariants if they overflowed. */
3083 #define CHECK_OP(N, MSG) \
3084 do { if (TREE_CODE_CLASS (TREE_CODE (TREE_OPERAND (t, N))) != 'c' \
3085 && !is_gimple_val (TREE_OPERAND (t, N))) \
3086 { error (MSG); return TREE_OPERAND (t, N); }} while (0)
3088 switch (TREE_CODE (t
))
3091 if (SSA_NAME_IN_FREE_LIST (t
))
3093 error ("SSA name in freelist but still referenced");
3099 x
= TREE_OPERAND (t
, 0);
3100 if (TREE_CODE (x
) == BIT_FIELD_REF
3101 && is_gimple_reg (TREE_OPERAND (x
, 0)))
3103 error ("GIMPLE register modified with BIT_FIELD_REF");
3109 /* Skip any references (they will be checked when we recurse down the
3110 tree) and ensure that any variable used as a prefix is marked
3112 for (x
= TREE_OPERAND (t
, 0);
3113 (handled_component_p (x
)
3114 || TREE_CODE (x
) == REALPART_EXPR
3115 || TREE_CODE (x
) == IMAGPART_EXPR
);
3116 x
= TREE_OPERAND (x
, 0))
3119 if (TREE_CODE (x
) != VAR_DECL
&& TREE_CODE (x
) != PARM_DECL
)
3121 if (!TREE_ADDRESSABLE (x
))
3123 error ("address taken, but ADDRESSABLE bit not set");
3129 x
= TREE_OPERAND (t
, 0);
3130 if (TREE_CODE (TREE_TYPE (x
)) != BOOLEAN_TYPE
)
3132 error ("non-boolean used in condition");
3139 case FIX_TRUNC_EXPR
:
3141 case FIX_FLOOR_EXPR
:
3142 case FIX_ROUND_EXPR
:
3147 case NON_LVALUE_EXPR
:
3148 case TRUTH_NOT_EXPR
:
3149 CHECK_OP (0, "Invalid operand to unary operator");
3156 case ARRAY_RANGE_REF
:
3158 case VIEW_CONVERT_EXPR
:
3159 /* We have a nest of references. Verify that each of the operands
3160 that determine where to reference is either a constant or a variable,
3161 verify that the base is valid, and then show we've already checked
3163 while (TREE_CODE (t
) == REALPART_EXPR
|| TREE_CODE (t
) == IMAGPART_EXPR
3164 || handled_component_p (t
))
3166 if (TREE_CODE (t
) == COMPONENT_REF
&& TREE_OPERAND (t
, 2))
3167 CHECK_OP (2, "Invalid COMPONENT_REF offset operator");
3168 else if (TREE_CODE (t
) == ARRAY_REF
3169 || TREE_CODE (t
) == ARRAY_RANGE_REF
)
3171 CHECK_OP (1, "Invalid array index.");
3172 if (TREE_OPERAND (t
, 2))
3173 CHECK_OP (2, "Invalid array lower bound.");
3174 if (TREE_OPERAND (t
, 3))
3175 CHECK_OP (3, "Invalid array stride.");
3177 else if (TREE_CODE (t
) == BIT_FIELD_REF
)
3179 CHECK_OP (1, "Invalid operand to BIT_FIELD_REF");
3180 CHECK_OP (2, "Invalid operand to BIT_FIELD_REF");
3183 t
= TREE_OPERAND (t
, 0);
3186 if (TREE_CODE_CLASS (TREE_CODE (t
)) != 'c'
3187 && !is_gimple_lvalue (t
))
3189 error ("Invalid reference prefix.");
3201 case UNORDERED_EXPR
:
3212 case TRUNC_DIV_EXPR
:
3214 case FLOOR_DIV_EXPR
:
3215 case ROUND_DIV_EXPR
:
3216 case TRUNC_MOD_EXPR
:
3218 case FLOOR_MOD_EXPR
:
3219 case ROUND_MOD_EXPR
:
3221 case EXACT_DIV_EXPR
:
3231 CHECK_OP (0, "Invalid operand to binary operator");
3232 CHECK_OP (1, "Invalid operand to binary operator");
3244 /* Verify STMT, return true if STMT is not in GIMPLE form.
3245 TODO: Implement type checking. */
3248 verify_stmt (tree stmt
, bool last_in_block
)
3252 if (!is_gimple_stmt (stmt
))
3254 error ("Is not a valid GIMPLE statement.");
3258 addr
= walk_tree (&stmt
, verify_expr
, NULL
, NULL
);
3261 debug_generic_stmt (addr
);
3265 /* If the statement is marked as part of an EH region, then it is
3266 expected that the statement could throw. Verify that when we
3267 have optimizations that simplify statements such that we prove
3268 that they cannot throw, that we update other data structures
3270 if (lookup_stmt_eh_region (stmt
) >= 0)
3272 if (!tree_could_throw_p (stmt
))
3274 error ("Statement marked for throw, but doesn't.");
3277 if (!last_in_block
&& tree_can_throw_internal (stmt
))
3279 error ("Statement marked for throw in middle of block.");
3287 debug_generic_stmt (stmt
);
3292 /* Return true when the T can be shared. */
3295 tree_node_can_be_shared (tree t
)
3297 if (TYPE_P (t
) || DECL_P (t
)
3298 /* We check for constants explicitly since they are not considered
3299 gimple invariants if they overflowed. */
3300 || TREE_CODE_CLASS (TREE_CODE (t
)) == 'c'
3301 || is_gimple_min_invariant (t
)
3302 || TREE_CODE (t
) == SSA_NAME
)
3305 while (((TREE_CODE (t
) == ARRAY_REF
|| TREE_CODE (t
) == ARRAY_RANGE_REF
)
3306 /* We check for constants explicitly since they are not considered
3307 gimple invariants if they overflowed. */
3308 && (TREE_CODE_CLASS (TREE_CODE (TREE_OPERAND (t
, 1))) == 'c'
3309 || is_gimple_min_invariant (TREE_OPERAND (t
, 1))))
3310 || (TREE_CODE (t
) == COMPONENT_REF
3311 || TREE_CODE (t
) == REALPART_EXPR
3312 || TREE_CODE (t
) == IMAGPART_EXPR
))
3313 t
= TREE_OPERAND (t
, 0);
3322 /* Called via walk_trees. Verify tree sharing. */
3325 verify_node_sharing (tree
* tp
, int *walk_subtrees
, void *data
)
3327 htab_t htab
= (htab_t
) data
;
3330 if (tree_node_can_be_shared (*tp
))
3332 *walk_subtrees
= false;
3336 slot
= htab_find_slot (htab
, *tp
, INSERT
);
3345 /* Verify the GIMPLE statement chain. */
3351 block_stmt_iterator bsi
;
3356 timevar_push (TV_TREE_STMT_VERIFY
);
3357 htab
= htab_create (37, htab_hash_pointer
, htab_eq_pointer
, NULL
);
3364 for (phi
= phi_nodes (bb
); phi
; phi
= PHI_CHAIN (phi
))
3366 int phi_num_args
= PHI_NUM_ARGS (phi
);
3368 for (i
= 0; i
< phi_num_args
; i
++)
3370 tree t
= PHI_ARG_DEF (phi
, i
);
3373 /* Addressable variables do have SSA_NAMEs but they
3374 are not considered gimple values. */
3375 if (TREE_CODE (t
) != SSA_NAME
3376 && TREE_CODE (t
) != FUNCTION_DECL
3377 && !is_gimple_val (t
))
3379 error ("PHI def is not a GIMPLE value");
3380 debug_generic_stmt (phi
);
3381 debug_generic_stmt (t
);
3385 addr
= walk_tree (&t
, verify_expr
, NULL
, NULL
);
3388 debug_generic_stmt (addr
);
3392 addr
= walk_tree (&t
, verify_node_sharing
, htab
, NULL
);
3395 error ("Incorrect sharing of tree nodes");
3396 debug_generic_stmt (phi
);
3397 debug_generic_stmt (addr
);
3403 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); )
3405 tree stmt
= bsi_stmt (bsi
);
3407 err
|= verify_stmt (stmt
, bsi_end_p (bsi
));
3408 addr
= walk_tree (&stmt
, verify_node_sharing
, htab
, NULL
);
3411 error ("Incorrect sharing of tree nodes");
3412 debug_generic_stmt (stmt
);
3413 debug_generic_stmt (addr
);
3420 internal_error ("verify_stmts failed.");
3423 timevar_pop (TV_TREE_STMT_VERIFY
);
3427 /* Verifies that the flow information is OK. */
3430 tree_verify_flow_info (void)
3434 block_stmt_iterator bsi
;
3438 if (ENTRY_BLOCK_PTR
->stmt_list
)
3440 error ("ENTRY_BLOCK has a statement list associated with it\n");
3444 if (EXIT_BLOCK_PTR
->stmt_list
)
3446 error ("EXIT_BLOCK has a statement list associated with it\n");
3450 for (e
= EXIT_BLOCK_PTR
->pred
; e
; e
= e
->pred_next
)
3451 if (e
->flags
& EDGE_FALLTHRU
)
3453 error ("Fallthru to exit from bb %d\n", e
->src
->index
);
3459 bool found_ctrl_stmt
= false;
3461 /* Skip labels on the start of basic block. */
3462 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
3464 if (TREE_CODE (bsi_stmt (bsi
)) != LABEL_EXPR
)
3467 if (label_to_block (LABEL_EXPR_LABEL (bsi_stmt (bsi
))) != bb
)
3469 error ("Label %s to block does not match in bb %d\n",
3470 IDENTIFIER_POINTER (DECL_NAME (bsi_stmt (bsi
))),
3475 if (decl_function_context (LABEL_EXPR_LABEL (bsi_stmt (bsi
)))
3476 != current_function_decl
)
3478 error ("Label %s has incorrect context in bb %d\n",
3479 IDENTIFIER_POINTER (DECL_NAME (bsi_stmt (bsi
))),
3485 /* Verify that body of basic block BB is free of control flow. */
3486 for (; !bsi_end_p (bsi
); bsi_next (&bsi
))
3488 tree stmt
= bsi_stmt (bsi
);
3490 if (found_ctrl_stmt
)
3492 error ("Control flow in the middle of basic block %d\n",
3497 if (stmt_ends_bb_p (stmt
))
3498 found_ctrl_stmt
= true;
3500 if (TREE_CODE (stmt
) == LABEL_EXPR
)
3502 error ("Label %s in the middle of basic block %d\n",
3503 IDENTIFIER_POINTER (DECL_NAME (stmt
)),
3508 bsi
= bsi_last (bb
);
3509 if (bsi_end_p (bsi
))
3512 stmt
= bsi_stmt (bsi
);
3514 if (is_ctrl_stmt (stmt
))
3516 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
3517 if (e
->flags
& EDGE_FALLTHRU
)
3519 error ("Fallthru edge after a control statement in bb %d \n",
3525 switch (TREE_CODE (stmt
))
3531 if (TREE_CODE (COND_EXPR_THEN (stmt
)) != GOTO_EXPR
3532 || TREE_CODE (COND_EXPR_ELSE (stmt
)) != GOTO_EXPR
)
3534 error ("Structured COND_EXPR at the end of bb %d\n", bb
->index
);
3538 extract_true_false_edges_from_block (bb
, &true_edge
, &false_edge
);
3540 if (!true_edge
|| !false_edge
3541 || !(true_edge
->flags
& EDGE_TRUE_VALUE
)
3542 || !(false_edge
->flags
& EDGE_FALSE_VALUE
)
3543 || (true_edge
->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
))
3544 || (false_edge
->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
))
3545 || bb
->succ
->succ_next
->succ_next
)
3547 error ("Wrong outgoing edge flags at end of bb %d\n",
3552 if (!has_label_p (true_edge
->dest
,
3553 GOTO_DESTINATION (COND_EXPR_THEN (stmt
))))
3555 error ("`then' label does not match edge at end of bb %d\n",
3560 if (!has_label_p (false_edge
->dest
,
3561 GOTO_DESTINATION (COND_EXPR_ELSE (stmt
))))
3563 error ("`else' label does not match edge at end of bb %d\n",
3571 if (simple_goto_p (stmt
))
3573 error ("Explicit goto at end of bb %d\n", bb
->index
);
3578 /* FIXME. We should double check that the labels in the
3579 destination blocks have their address taken. */
3580 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
3581 if ((e
->flags
& (EDGE_FALLTHRU
| EDGE_TRUE_VALUE
3582 | EDGE_FALSE_VALUE
))
3583 || !(e
->flags
& EDGE_ABNORMAL
))
3585 error ("Wrong outgoing edge flags at end of bb %d\n",
3593 if (!bb
->succ
|| bb
->succ
->succ_next
3594 || (bb
->succ
->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
3595 | EDGE_TRUE_VALUE
| EDGE_FALSE_VALUE
)))
3597 error ("Wrong outgoing edge flags at end of bb %d\n", bb
->index
);
3600 if (bb
->succ
->dest
!= EXIT_BLOCK_PTR
)
3602 error ("Return edge does not point to exit in bb %d\n",
3615 vec
= SWITCH_LABELS (stmt
);
3616 n
= TREE_VEC_LENGTH (vec
);
3618 /* Mark all the destination basic blocks. */
3619 for (i
= 0; i
< n
; ++i
)
3621 tree lab
= CASE_LABEL (TREE_VEC_ELT (vec
, i
));
3622 basic_block label_bb
= label_to_block (lab
);
3624 gcc_assert (!label_bb
->aux
|| label_bb
->aux
== (void *)1);
3625 label_bb
->aux
= (void *)1;
3628 /* Verify that the case labels are sorted. */
3629 prev
= TREE_VEC_ELT (vec
, 0);
3630 for (i
= 1; i
< n
- 1; ++i
)
3632 tree c
= TREE_VEC_ELT (vec
, i
);
3635 error ("Found default case not at end of case vector");
3639 if (! tree_int_cst_lt (CASE_LOW (prev
), CASE_LOW (c
)))
3641 error ("Case labels not sorted:\n ");
3642 print_generic_expr (stderr
, prev
, 0);
3643 fprintf (stderr
," is greater than ");
3644 print_generic_expr (stderr
, c
, 0);
3645 fprintf (stderr
," but comes before it.\n");
3650 if (CASE_LOW (TREE_VEC_ELT (vec
, n
- 1)))
3652 error ("No default case found at end of case vector");
3656 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
3660 error ("Extra outgoing edge %d->%d\n",
3661 bb
->index
, e
->dest
->index
);
3664 e
->dest
->aux
= (void *)2;
3665 if ((e
->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
3666 | EDGE_TRUE_VALUE
| EDGE_FALSE_VALUE
)))
3668 error ("Wrong outgoing edge flags at end of bb %d\n",
3674 /* Check that we have all of them. */
3675 for (i
= 0; i
< n
; ++i
)
3677 tree lab
= CASE_LABEL (TREE_VEC_ELT (vec
, i
));
3678 basic_block label_bb
= label_to_block (lab
);
3680 if (label_bb
->aux
!= (void *)2)
3682 error ("Missing edge %i->%i\n",
3683 bb
->index
, label_bb
->index
);
3688 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
3689 e
->dest
->aux
= (void *)0;
3696 if (dom_computed
[CDI_DOMINATORS
] >= DOM_NO_FAST_QUERY
)
3697 verify_dominators (CDI_DOMINATORS
);
3703 /* Updates phi nodes after creating forwarder block joined
3704 by edge FALLTHRU. */
3707 tree_make_forwarder_block (edge fallthru
)
3710 basic_block dummy
, bb
;
3711 tree phi
, new_phi
, var
, prev
, next
;
3713 dummy
= fallthru
->src
;
3714 bb
= fallthru
->dest
;
3716 if (!bb
->pred
->pred_next
)
3719 /* If we redirected a branch we must create new phi nodes at the
3721 for (phi
= phi_nodes (dummy
); phi
; phi
= PHI_CHAIN (phi
))
3723 var
= PHI_RESULT (phi
);
3724 new_phi
= create_phi_node (var
, bb
);
3725 SSA_NAME_DEF_STMT (var
) = new_phi
;
3726 SET_PHI_RESULT (phi
, make_ssa_name (SSA_NAME_VAR (var
), phi
));
3727 add_phi_arg (&new_phi
, PHI_RESULT (phi
), fallthru
);
3730 /* Ensure that the PHI node chain is in the same order. */
3732 for (phi
= phi_nodes (bb
); phi
; phi
= next
)
3734 next
= PHI_CHAIN (phi
);
3735 PHI_CHAIN (phi
) = prev
;
3738 set_phi_nodes (bb
, prev
);
3740 /* Add the arguments we have stored on edges. */
3741 for (e
= bb
->pred
; e
; e
= e
->pred_next
)
3746 for (phi
= phi_nodes (bb
), var
= PENDING_STMT (e
);
3748 phi
= PHI_CHAIN (phi
), var
= TREE_CHAIN (var
))
3749 add_phi_arg (&phi
, TREE_VALUE (var
), e
);
3751 PENDING_STMT (e
) = NULL
;
3756 /* Return true if basic block BB does nothing except pass control
3757 flow to another block and that we can safely insert a label at
3758 the start of the successor block. */
3761 tree_forwarder_block_p (basic_block bb
)
3763 block_stmt_iterator bsi
;
3766 /* If we have already determined that this block is not forwardable,
3767 then no further checks are necessary. */
3768 if (! bb_ann (bb
)->forwardable
)
3771 /* BB must have a single outgoing normal edge. Otherwise it can not be
3772 a forwarder block. */
3774 || bb
->succ
->succ_next
3775 || bb
->succ
->dest
== EXIT_BLOCK_PTR
3776 || (bb
->succ
->flags
& EDGE_ABNORMAL
)
3777 || bb
== ENTRY_BLOCK_PTR
)
3779 bb_ann (bb
)->forwardable
= 0;
3783 /* Successors of the entry block are not forwarders. */
3784 for (e
= ENTRY_BLOCK_PTR
->succ
; e
; e
= e
->succ_next
)
3787 bb_ann (bb
)->forwardable
= 0;
3791 /* BB can not have any PHI nodes. This could potentially be relaxed
3792 early in compilation if we re-rewrote the variables appearing in
3793 any PHI nodes in forwarder blocks. */
3796 bb_ann (bb
)->forwardable
= 0;
3800 /* Now walk through the statements. We can ignore labels, anything else
3801 means this is not a forwarder block. */
3802 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
3804 tree stmt
= bsi_stmt (bsi
);
3806 switch (TREE_CODE (stmt
))
3809 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt
)))
3814 bb_ann (bb
)->forwardable
= 0;
3823 /* Thread jumps over empty statements.
3825 This code should _not_ thread over obviously equivalent conditions
3826 as that requires nontrivial updates to the SSA graph. */
3831 edge e
, next
, last
, old
;
3832 basic_block bb
, dest
, tmp
, old_dest
, dom
;
3835 bool retval
= false;
3838 bb_ann (bb
)->forwardable
= 1;
3840 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
, EXIT_BLOCK_PTR
, next_bb
)
3842 /* Don't waste time on unreachable blocks. */
3846 /* Nor on forwarders. */
3847 if (tree_forwarder_block_p (bb
))
3850 /* This block is now part of a forwarding path, mark it as not
3851 forwardable so that we can detect loops. This bit will be
3853 bb_ann (bb
)->forwardable
= 0;
3855 /* Examine each of our block's successors to see if it is
3857 for (e
= bb
->succ
; e
; e
= next
)
3861 next
= e
->succ_next
;
3863 /* If the edge is abnormal or its destination is not
3864 forwardable, then there's nothing to do. */
3865 if ((e
->flags
& EDGE_ABNORMAL
)
3866 || !tree_forwarder_block_p (e
->dest
))
3870 freq
= EDGE_FREQUENCY (e
);
3872 /* Now walk through as many forwarder block as possible to
3873 find the ultimate destination we want to thread our jump
3875 last
= e
->dest
->succ
;
3876 bb_ann (e
->dest
)->forwardable
= 0;
3877 for (dest
= e
->dest
->succ
->dest
;
3878 tree_forwarder_block_p (dest
);
3880 dest
= dest
->succ
->dest
)
3882 /* An infinite loop detected. We redirect the edge anyway, so
3883 that the loop is shrunk into single basic block. */
3884 if (!bb_ann (dest
)->forwardable
)
3887 if (dest
->succ
->dest
== EXIT_BLOCK_PTR
)
3890 bb_ann (dest
)->forwardable
= 0;
3891 dest
->frequency
-= freq
;
3892 if (dest
->frequency
< 0)
3893 dest
->frequency
= 0;
3894 dest
->count
-= count
;
3895 if (dest
->count
< 0)
3897 dest
->succ
->count
-= count
;
3898 if (dest
->succ
->count
< 0)
3899 dest
->succ
->count
= 0;
3902 /* Reset the forwardable marks to 1. */
3905 tmp
= tmp
->succ
->dest
)
3906 bb_ann (tmp
)->forwardable
= 1;
3908 if (dest
== e
->dest
)
3911 old
= find_edge (bb
, dest
);
3914 /* If there already is an edge, check whether the values
3915 in phi nodes differ. */
3916 if (!phi_alternatives_equal (dest
, last
, old
))
3918 /* The previous block is forwarder. Redirect our jump
3919 to that target instead since we know it has no PHI
3920 nodes that will need updating. */
3923 /* That might mean that no forwarding at all is possible. */
3924 if (dest
== e
->dest
)
3927 old
= find_edge (bb
, dest
);
3931 /* Perform the redirection. */
3934 e
= redirect_edge_and_branch (e
, dest
);
3938 /* Update PHI nodes. We know that the new argument should
3939 have the same value as the argument associated with LAST.
3940 Otherwise we would have changed our target block above. */
3941 for (phi
= phi_nodes (dest
); phi
; phi
= PHI_CHAIN (phi
))
3943 arg
= phi_arg_from_edge (phi
, last
);
3944 gcc_assert (arg
>= 0);
3945 add_phi_arg (&phi
, PHI_ARG_DEF (phi
, arg
), e
);
3949 /* Update the dominators. */
3950 if (dom_computed
[CDI_DOMINATORS
] >= DOM_CONS_OK
)
3952 /* Remove the unreachable blocks (observe that if all blocks
3953 were reachable before, only those in the path we threaded
3954 over and did not have any predecessor outside of the path
3955 become unreachable). */
3956 for (; old_dest
!= dest
; old_dest
= tmp
)
3958 tmp
= old_dest
->succ
->dest
;
3963 delete_basic_block (old_dest
);
3965 /* If the dominator of the destination was in the path, set its
3966 dominator to the start of the redirected edge. */
3967 if (get_immediate_dominator (CDI_DOMINATORS
, old_dest
) == NULL
)
3968 set_immediate_dominator (CDI_DOMINATORS
, old_dest
, bb
);
3970 /* Now proceed like if we forwarded just over one edge at a time.
3971 Algorithm for forwarding over edge A --> B then is
3974 idom (B) = idom (A);
3975 recount_idom (A); */
3977 for (; old_dest
!= dest
; old_dest
= tmp
)
3979 tmp
= old_dest
->succ
->dest
;
3981 if (get_immediate_dominator (CDI_DOMINATORS
, tmp
) == old_dest
)
3983 dom
= get_immediate_dominator (CDI_DOMINATORS
, old_dest
);
3984 set_immediate_dominator (CDI_DOMINATORS
, tmp
, dom
);
3987 dom
= recount_dominator (CDI_DOMINATORS
, old_dest
);
3988 set_immediate_dominator (CDI_DOMINATORS
, old_dest
, dom
);
3993 /* Reset the forwardable bit on our block since it's no longer in
3994 a forwarding chain path. */
3995 bb_ann (bb
)->forwardable
= 1;
4002 /* Return a non-special label in the head of basic block BLOCK.
4003 Create one if it doesn't exist. */
4006 tree_block_label (basic_block bb
)
4008 block_stmt_iterator i
, s
= bsi_start (bb
);
4012 for (i
= s
; !bsi_end_p (i
); first
= false, bsi_next (&i
))
4014 stmt
= bsi_stmt (i
);
4015 if (TREE_CODE (stmt
) != LABEL_EXPR
)
4017 label
= LABEL_EXPR_LABEL (stmt
);
4018 if (!DECL_NONLOCAL (label
))
4021 bsi_move_before (&i
, &s
);
4026 label
= create_artificial_label ();
4027 stmt
= build1 (LABEL_EXPR
, void_type_node
, label
);
4028 bsi_insert_before (&s
, stmt
, BSI_NEW_STMT
);
4033 /* Attempt to perform edge redirection by replacing a possibly complex
4034 jump instruction by a goto or by removing the jump completely.
4035 This can apply only if all edges now point to the same block. The
4036 parameters and return values are equivalent to
4037 redirect_edge_and_branch. */
4040 tree_try_redirect_by_replacing_jump (edge e
, basic_block target
)
4042 basic_block src
= e
->src
;
4044 block_stmt_iterator b
;
4047 /* Verify that all targets will be TARGET. */
4048 for (tmp
= src
->succ
; tmp
; tmp
= tmp
->succ_next
)
4049 if (tmp
->dest
!= target
&& tmp
!= e
)
4058 stmt
= bsi_stmt (b
);
4060 if (TREE_CODE (stmt
) == COND_EXPR
4061 || TREE_CODE (stmt
) == SWITCH_EXPR
)
4064 e
= ssa_redirect_edge (e
, target
);
4065 e
->flags
= EDGE_FALLTHRU
;
4073 /* Redirect E to DEST. Return NULL on failure. Otherwise, return the
4074 edge representing the redirected branch. */
4077 tree_redirect_edge_and_branch (edge e
, basic_block dest
)
4079 basic_block bb
= e
->src
;
4080 block_stmt_iterator bsi
;
4084 if (e
->flags
& (EDGE_ABNORMAL_CALL
| EDGE_EH
))
4087 if (e
->src
!= ENTRY_BLOCK_PTR
4088 && (ret
= tree_try_redirect_by_replacing_jump (e
, dest
)))
4091 if (e
->dest
== dest
)
4094 label
= tree_block_label (dest
);
4096 bsi
= bsi_last (bb
);
4097 stmt
= bsi_end_p (bsi
) ? NULL
: bsi_stmt (bsi
);
4099 switch (stmt
? TREE_CODE (stmt
) : ERROR_MARK
)
4102 stmt
= (e
->flags
& EDGE_TRUE_VALUE
4103 ? COND_EXPR_THEN (stmt
)
4104 : COND_EXPR_ELSE (stmt
));
4105 GOTO_DESTINATION (stmt
) = label
;
4109 /* No non-abnormal edges should lead from a non-simple goto, and
4110 simple ones should be represented implicitly. */
4115 tree vec
= SWITCH_LABELS (stmt
);
4116 size_t i
, n
= TREE_VEC_LENGTH (vec
);
4118 for (i
= 0; i
< n
; ++i
)
4120 tree elt
= TREE_VEC_ELT (vec
, i
);
4121 if (label_to_block (CASE_LABEL (elt
)) == e
->dest
)
4122 CASE_LABEL (elt
) = label
;
4129 e
->flags
|= EDGE_FALLTHRU
;
4133 /* Otherwise it must be a fallthru edge, and we don't need to
4134 do anything besides redirecting it. */
4135 gcc_assert (e
->flags
& EDGE_FALLTHRU
);
4139 /* Update/insert PHI nodes as necessary. */
4141 /* Now update the edges in the CFG. */
4142 e
= ssa_redirect_edge (e
, dest
);
4148 /* Simple wrapper, as we can always redirect fallthru edges. */
4151 tree_redirect_edge_and_branch_force (edge e
, basic_block dest
)
4153 e
= tree_redirect_edge_and_branch (e
, dest
);
4160 /* Splits basic block BB after statement STMT (but at least after the
4161 labels). If STMT is NULL, BB is split just after the labels. */
4164 tree_split_block (basic_block bb
, void *stmt
)
4166 block_stmt_iterator bsi
, bsi_tgt
;
4171 new_bb
= create_empty_bb (bb
);
4173 /* Redirect the outgoing edges. */
4174 new_bb
->succ
= bb
->succ
;
4176 for (e
= new_bb
->succ
; e
; e
= e
->succ_next
)
4179 if (stmt
&& TREE_CODE ((tree
) stmt
) == LABEL_EXPR
)
4182 /* Move everything from BSI to the new basic block. */
4183 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
4185 act
= bsi_stmt (bsi
);
4186 if (TREE_CODE (act
) == LABEL_EXPR
)
4199 bsi_tgt
= bsi_start (new_bb
);
4200 while (!bsi_end_p (bsi
))
4202 act
= bsi_stmt (bsi
);
4204 bsi_insert_after (&bsi_tgt
, act
, BSI_NEW_STMT
);
4211 /* Moves basic block BB after block AFTER. */
4214 tree_move_block_after (basic_block bb
, basic_block after
)
4216 if (bb
->prev_bb
== after
)
4220 link_block (bb
, after
);
4226 /* Return true if basic_block can be duplicated. */
4229 tree_can_duplicate_bb_p (basic_block bb ATTRIBUTE_UNUSED
)
4235 /* Create a duplicate of the basic block BB. NOTE: This does not
4236 preserve SSA form. */
4239 tree_duplicate_bb (basic_block bb
)
4242 block_stmt_iterator bsi
, bsi_tgt
;
4244 ssa_op_iter op_iter
;
4246 new_bb
= create_empty_bb (EXIT_BLOCK_PTR
->prev_bb
);
4248 for (phi
= phi_nodes (bb
); phi
; phi
= TREE_CHAIN (phi
))
4250 mark_for_rewrite (PHI_RESULT (phi
));
4253 bsi_tgt
= bsi_start (new_bb
);
4254 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
4256 tree stmt
= bsi_stmt (bsi
);
4259 if (TREE_CODE (stmt
) == LABEL_EXPR
)
4262 /* Record the definitions. */
4263 get_stmt_operands (stmt
);
4265 FOR_EACH_SSA_TREE_OPERAND (val
, stmt
, op_iter
, SSA_OP_ALL_DEFS
)
4266 mark_for_rewrite (val
);
4268 copy
= unshare_expr (stmt
);
4270 /* Copy also the virtual operands. */
4271 get_stmt_ann (copy
);
4272 copy_virtual_operands (copy
, stmt
);
4274 bsi_insert_after (&bsi_tgt
, copy
, BSI_NEW_STMT
);
4281 /* Dump FUNCTION_DECL FN to file FILE using FLAGS (see TDF_* in tree.h) */
4284 dump_function_to_file (tree fn
, FILE *file
, int flags
)
4286 tree arg
, vars
, var
;
4287 bool ignore_topmost_bind
= false, any_var
= false;
4291 fprintf (file
, "%s (", lang_hooks
.decl_printable_name (fn
, 2));
4293 arg
= DECL_ARGUMENTS (fn
);
4296 print_generic_expr (file
, arg
, dump_flags
);
4297 if (TREE_CHAIN (arg
))
4298 fprintf (file
, ", ");
4299 arg
= TREE_CHAIN (arg
);
4301 fprintf (file
, ")\n");
4303 if (flags
& TDF_RAW
)
4305 dump_node (fn
, TDF_SLIM
| flags
, file
);
4309 /* When GIMPLE is lowered, the variables are no longer available in
4310 BIND_EXPRs, so display them separately. */
4311 if (cfun
&& cfun
->unexpanded_var_list
)
4313 ignore_topmost_bind
= true;
4315 fprintf (file
, "{\n");
4316 for (vars
= cfun
->unexpanded_var_list
; vars
; vars
= TREE_CHAIN (vars
))
4318 var
= TREE_VALUE (vars
);
4320 print_generic_decl (file
, var
, flags
);
4321 fprintf (file
, "\n");
4327 if (basic_block_info
)
4329 /* Make a CFG based dump. */
4330 check_bb_profile (ENTRY_BLOCK_PTR
, file
);
4331 if (!ignore_topmost_bind
)
4332 fprintf (file
, "{\n");
4334 if (any_var
&& n_basic_blocks
)
4335 fprintf (file
, "\n");
4338 dump_generic_bb (file
, bb
, 2, flags
);
4340 fprintf (file
, "}\n");
4341 check_bb_profile (EXIT_BLOCK_PTR
, file
);
4347 /* Make a tree based dump. */
4348 chain
= DECL_SAVED_TREE (fn
);
4350 if (TREE_CODE (chain
) == BIND_EXPR
)
4352 if (ignore_topmost_bind
)
4354 chain
= BIND_EXPR_BODY (chain
);
4362 if (!ignore_topmost_bind
)
4363 fprintf (file
, "{\n");
4368 fprintf (file
, "\n");
4370 print_generic_stmt_indented (file
, chain
, flags
, indent
);
4371 if (ignore_topmost_bind
)
4372 fprintf (file
, "}\n");
4375 fprintf (file
, "\n\n");
4379 /* Pretty print of the loops intermediate representation. */
4380 static void print_loop (FILE *, struct loop
*, int);
4381 static void print_pred_bbs (FILE *, edge
);
4382 static void print_succ_bbs (FILE *, edge
);
4385 /* Print the predecessors indexes of edge E on FILE. */
4388 print_pred_bbs (FILE *file
, edge e
)
4393 else if (e
->pred_next
== NULL
)
4394 fprintf (file
, "bb_%d", e
->src
->index
);
4398 fprintf (file
, "bb_%d, ", e
->src
->index
);
4399 print_pred_bbs (file
, e
->pred_next
);
4404 /* Print the successors indexes of edge E on FILE. */
4407 print_succ_bbs (FILE *file
, edge e
)
4411 else if (e
->succ_next
== NULL
)
4412 fprintf (file
, "bb_%d", e
->dest
->index
);
4415 fprintf (file
, "bb_%d, ", e
->dest
->index
);
4416 print_succ_bbs (file
, e
->succ_next
);
4421 /* Pretty print LOOP on FILE, indented INDENT spaces. */
4424 print_loop (FILE *file
, struct loop
*loop
, int indent
)
4432 s_indent
= (char *) alloca ((size_t) indent
+ 1);
4433 memset ((void *) s_indent
, ' ', (size_t) indent
);
4434 s_indent
[indent
] = '\0';
4436 /* Print the loop's header. */
4437 fprintf (file
, "%sloop_%d\n", s_indent
, loop
->num
);
4439 /* Print the loop's body. */
4440 fprintf (file
, "%s{\n", s_indent
);
4442 if (bb
->loop_father
== loop
)
4444 /* Print the basic_block's header. */
4445 fprintf (file
, "%s bb_%d (preds = {", s_indent
, bb
->index
);
4446 print_pred_bbs (file
, bb
->pred
);
4447 fprintf (file
, "}, succs = {");
4448 print_succ_bbs (file
, bb
->succ
);
4449 fprintf (file
, "})\n");
4451 /* Print the basic_block's body. */
4452 fprintf (file
, "%s {\n", s_indent
);
4453 tree_dump_bb (bb
, file
, indent
+ 4);
4454 fprintf (file
, "%s }\n", s_indent
);
4457 print_loop (file
, loop
->inner
, indent
+ 2);
4458 fprintf (file
, "%s}\n", s_indent
);
4459 print_loop (file
, loop
->next
, indent
);
4463 /* Follow a CFG edge from the entry point of the program, and on entry
4464 of a loop, pretty print the loop structure on FILE. */
4467 print_loop_ir (FILE *file
)
4471 bb
= BASIC_BLOCK (0);
4472 if (bb
&& bb
->loop_father
)
4473 print_loop (file
, bb
->loop_father
, 0);
4477 /* Debugging loops structure at tree level. */
4480 debug_loop_ir (void)
4482 print_loop_ir (stderr
);
4486 /* Return true if BB ends with a call, possibly followed by some
4487 instructions that must stay with the call. Return false,
4491 tree_block_ends_with_call_p (basic_block bb
)
4493 block_stmt_iterator bsi
= bsi_last (bb
);
4494 return get_call_expr_in (bsi_stmt (bsi
)) != NULL
;
4498 /* Return true if BB ends with a conditional branch. Return false,
4502 tree_block_ends_with_condjump_p (basic_block bb
)
4504 tree stmt
= tsi_stmt (bsi_last (bb
).tsi
);
4505 return (TREE_CODE (stmt
) == COND_EXPR
);
4509 /* Return true if we need to add fake edge to exit at statement T.
4510 Helper function for tree_flow_call_edges_add. */
4513 need_fake_edge_p (tree t
)
4517 /* NORETURN and LONGJMP calls already have an edge to exit.
4518 CONST, PURE and ALWAYS_RETURN calls do not need one.
4519 We don't currently check for CONST and PURE here, although
4520 it would be a good idea, because those attributes are
4521 figured out from the RTL in mark_constant_function, and
4522 the counter incrementation code from -fprofile-arcs
4523 leads to different results from -fbranch-probabilities. */
4524 call
= get_call_expr_in (t
);
4526 && !(call_expr_flags (call
) &
4527 (ECF_NORETURN
| ECF_LONGJMP
| ECF_ALWAYS_RETURN
)))
4530 if (TREE_CODE (t
) == ASM_EXPR
4531 && (ASM_VOLATILE_P (t
) || ASM_INPUT_P (t
)))
4538 /* Add fake edges to the function exit for any non constant and non
4539 noreturn calls, volatile inline assembly in the bitmap of blocks
4540 specified by BLOCKS or to the whole CFG if BLOCKS is zero. Return
4541 the number of blocks that were split.
4543 The goal is to expose cases in which entering a basic block does
4544 not imply that all subsequent instructions must be executed. */
4547 tree_flow_call_edges_add (sbitmap blocks
)
4550 int blocks_split
= 0;
4551 int last_bb
= last_basic_block
;
4552 bool check_last_block
= false;
4554 if (n_basic_blocks
== 0)
4558 check_last_block
= true;
4560 check_last_block
= TEST_BIT (blocks
, EXIT_BLOCK_PTR
->prev_bb
->index
);
4562 /* In the last basic block, before epilogue generation, there will be
4563 a fallthru edge to EXIT. Special care is required if the last insn
4564 of the last basic block is a call because make_edge folds duplicate
4565 edges, which would result in the fallthru edge also being marked
4566 fake, which would result in the fallthru edge being removed by
4567 remove_fake_edges, which would result in an invalid CFG.
4569 Moreover, we can't elide the outgoing fake edge, since the block
4570 profiler needs to take this into account in order to solve the minimal
4571 spanning tree in the case that the call doesn't return.
4573 Handle this by adding a dummy instruction in a new last basic block. */
4574 if (check_last_block
)
4576 basic_block bb
= EXIT_BLOCK_PTR
->prev_bb
;
4577 block_stmt_iterator bsi
= bsi_last (bb
);
4579 if (!bsi_end_p (bsi
))
4582 if (need_fake_edge_p (t
))
4586 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
4587 if (e
->dest
== EXIT_BLOCK_PTR
)
4589 bsi_insert_on_edge (e
, build_empty_stmt ());
4590 bsi_commit_edge_inserts ((int *)NULL
);
4596 /* Now add fake edges to the function exit for any non constant
4597 calls since there is no way that we can determine if they will
4599 for (i
= 0; i
< last_bb
; i
++)
4601 basic_block bb
= BASIC_BLOCK (i
);
4602 block_stmt_iterator bsi
;
4603 tree stmt
, last_stmt
;
4608 if (blocks
&& !TEST_BIT (blocks
, i
))
4611 bsi
= bsi_last (bb
);
4612 if (!bsi_end_p (bsi
))
4614 last_stmt
= bsi_stmt (bsi
);
4617 stmt
= bsi_stmt (bsi
);
4618 if (need_fake_edge_p (stmt
))
4621 /* The handling above of the final block before the
4622 epilogue should be enough to verify that there is
4623 no edge to the exit block in CFG already.
4624 Calling make_edge in such case would cause us to
4625 mark that edge as fake and remove it later. */
4626 #ifdef ENABLE_CHECKING
4627 if (stmt
== last_stmt
)
4628 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
4629 gcc_assert (e
->dest
!= EXIT_BLOCK_PTR
);
4632 /* Note that the following may create a new basic block
4633 and renumber the existing basic blocks. */
4634 if (stmt
!= last_stmt
)
4636 e
= split_block (bb
, stmt
);
4640 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
4644 while (!bsi_end_p (bsi
));
4649 verify_flow_info ();
4651 return blocks_split
;
4655 tree_purge_dead_eh_edges (basic_block bb
)
4657 bool changed
= false;
4659 tree stmt
= last_stmt (bb
);
4661 if (stmt
&& tree_can_throw_internal (stmt
))
4664 for (e
= bb
->succ
; e
; e
= next
)
4666 next
= e
->succ_next
;
4667 if (e
->flags
& EDGE_EH
)
4669 ssa_remove_edge (e
);
4678 tree_purge_all_dead_eh_edges (bitmap blocks
)
4680 bool changed
= false;
4683 EXECUTE_IF_SET_IN_BITMAP (blocks
, 0, i
,
4684 { changed
|= tree_purge_dead_eh_edges (BASIC_BLOCK (i
)); });
4689 struct cfg_hooks tree_cfg_hooks
= {
4691 tree_verify_flow_info
,
4692 tree_dump_bb
, /* dump_bb */
4693 create_bb
, /* create_basic_block */
4694 tree_redirect_edge_and_branch
,/* redirect_edge_and_branch */
4695 tree_redirect_edge_and_branch_force
,/* redirect_edge_and_branch_force */
4696 remove_bb
, /* delete_basic_block */
4697 tree_split_block
, /* split_block */
4698 tree_move_block_after
, /* move_block_after */
4699 tree_can_merge_blocks_p
, /* can_merge_blocks_p */
4700 tree_merge_blocks
, /* merge_blocks */
4701 tree_predict_edge
, /* predict_edge */
4702 tree_predicted_by_p
, /* predicted_by_p */
4703 tree_can_duplicate_bb_p
, /* can_duplicate_block_p */
4704 tree_duplicate_bb
, /* duplicate_block */
4705 tree_split_edge
, /* split_edge */
4706 tree_make_forwarder_block
, /* make_forward_block */
4707 NULL
, /* tidy_fallthru_edge */
4708 tree_block_ends_with_call_p
, /* block_ends_with_call_p */
4709 tree_block_ends_with_condjump_p
, /* block_ends_with_condjump_p */
4710 tree_flow_call_edges_add
/* flow_call_edges_add */
4714 /* Split all critical edges. */
4717 split_critical_edges (void)
4724 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
4725 if (EDGE_CRITICAL_P (e
) && !(e
->flags
& EDGE_ABNORMAL
))
4732 struct tree_opt_pass pass_split_crit_edges
=
4734 "crited", /* name */
4736 split_critical_edges
, /* execute */
4739 0, /* static_pass_number */
4740 TV_TREE_SPLIT_EDGES
, /* tv_id */
4741 PROP_cfg
, /* properties required */
4742 PROP_no_crit_edges
, /* properties_provided */
4743 0, /* properties_destroyed */
4744 0, /* todo_flags_start */
4745 TODO_dump_func
, /* todo_flags_finish */
4750 /* Return EXP if it is a valid GIMPLE rvalue, else gimplify it into
4751 a temporary, make sure and register it to be renamed if necessary,
4752 and finally return the temporary. Put the statements to compute
4753 EXP before the current statement in BSI. */
4756 gimplify_val (block_stmt_iterator
*bsi
, tree type
, tree exp
)
4758 tree t
, new_stmt
, orig_stmt
;
4760 if (is_gimple_val (exp
))
4763 t
= make_rename_temp (type
, NULL
);
4764 new_stmt
= build (MODIFY_EXPR
, type
, t
, exp
);
4766 orig_stmt
= bsi_stmt (*bsi
);
4767 SET_EXPR_LOCUS (new_stmt
, EXPR_LOCUS (orig_stmt
));
4768 TREE_BLOCK (new_stmt
) = TREE_BLOCK (orig_stmt
);
4770 bsi_insert_before (bsi
, new_stmt
, BSI_SAME_STMT
);
4775 /* Build a ternary operation and gimplify it. Emit code before BSI.
4776 Return the gimple_val holding the result. */
4779 gimplify_build3 (block_stmt_iterator
*bsi
, enum tree_code code
,
4780 tree type
, tree a
, tree b
, tree c
)
4784 ret
= fold (build3 (code
, type
, a
, b
, c
));
4787 return gimplify_val (bsi
, type
, ret
);
4790 /* Build a binary operation and gimplify it. Emit code before BSI.
4791 Return the gimple_val holding the result. */
4794 gimplify_build2 (block_stmt_iterator
*bsi
, enum tree_code code
,
4795 tree type
, tree a
, tree b
)
4799 ret
= fold (build2 (code
, type
, a
, b
));
4802 return gimplify_val (bsi
, type
, ret
);
4805 /* Build a unary operation and gimplify it. Emit code before BSI.
4806 Return the gimple_val holding the result. */
4809 gimplify_build1 (block_stmt_iterator
*bsi
, enum tree_code code
, tree type
,
4814 ret
= fold (build1 (code
, type
, a
));
4817 return gimplify_val (bsi
, type
, ret
);
4822 /* Emit return warnings. */
4825 execute_warn_function_return (void)
4827 #ifdef USE_MAPPED_LOCATION
4828 source_location location
;
4835 if (warn_missing_noreturn
4836 && !TREE_THIS_VOLATILE (cfun
->decl
)
4837 && EXIT_BLOCK_PTR
->pred
== NULL
4838 && !lang_hooks
.function
.missing_noreturn_ok_p (cfun
->decl
))
4839 warning ("%Jfunction might be possible candidate for attribute `noreturn'",
4842 /* If we have a path to EXIT, then we do return. */
4843 if (TREE_THIS_VOLATILE (cfun
->decl
)
4844 && EXIT_BLOCK_PTR
->pred
!= NULL
)
4846 #ifdef USE_MAPPED_LOCATION
4847 location
= UNKNOWN_LOCATION
;
4851 for (e
= EXIT_BLOCK_PTR
->pred
; e
; e
= e
->pred_next
)
4853 last
= last_stmt (e
->src
);
4854 if (TREE_CODE (last
) == RETURN_EXPR
4855 #ifdef USE_MAPPED_LOCATION
4856 && (location
= EXPR_LOCATION (last
)) != UNKNOWN_LOCATION
)
4858 && (locus
= EXPR_LOCUS (last
)) != NULL
)
4862 #ifdef USE_MAPPED_LOCATION
4863 if (location
== UNKNOWN_LOCATION
)
4864 location
= cfun
->function_end_locus
;
4865 warning ("%H`noreturn' function does return", &location
);
4868 locus
= &cfun
->function_end_locus
;
4869 warning ("%H`noreturn' function does return", locus
);
4873 /* If we see "return;" in some basic block, then we do reach the end
4874 without returning a value. */
4875 else if (warn_return_type
4876 && EXIT_BLOCK_PTR
->pred
!= NULL
4877 && !VOID_TYPE_P (TREE_TYPE (TREE_TYPE (cfun
->decl
))))
4879 for (e
= EXIT_BLOCK_PTR
->pred
; e
; e
= e
->pred_next
)
4881 tree last
= last_stmt (e
->src
);
4882 if (TREE_CODE (last
) == RETURN_EXPR
4883 && TREE_OPERAND (last
, 0) == NULL
)
4885 #ifdef USE_MAPPED_LOCATION
4886 location
= EXPR_LOCATION (last
);
4887 if (location
== UNKNOWN_LOCATION
)
4888 location
= cfun
->function_end_locus
;
4889 warning ("%Hcontrol reaches end of non-void function", &location
);
4891 locus
= EXPR_LOCUS (last
);
4893 locus
= &cfun
->function_end_locus
;
4894 warning ("%Hcontrol reaches end of non-void function", locus
);
4903 /* Given a basic block B which ends with a conditional and has
4904 precisely two successors, determine which of the edges is taken if
4905 the conditional is true and which is taken if the conditional is
4906 false. Set TRUE_EDGE and FALSE_EDGE appropriately. */
4909 extract_true_false_edges_from_block (basic_block b
,
4915 if (e
->flags
& EDGE_TRUE_VALUE
)
4918 *false_edge
= e
->succ_next
;
4923 *true_edge
= e
->succ_next
;
4927 struct tree_opt_pass pass_warn_function_return
=
4931 execute_warn_function_return
, /* execute */
4934 0, /* static_pass_number */
4936 PROP_cfg
, /* properties_required */
4937 0, /* properties_provided */
4938 0, /* properties_destroyed */
4939 0, /* todo_flags_start */
4940 0, /* todo_flags_finish */
4944 #include "gt-tree-cfg.h"