1 /* Control flow functions for trees.
2 Copyright (C) 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
3 Contributed by Diego Novillo <dnovillo@redhat.com>
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 GCC is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to
19 the Free Software Foundation, 59 Temple Place - Suite 330,
20 Boston, MA 02111-1307, USA. */
24 #include "coretypes.h"
29 #include "hard-reg-set.h"
30 #include "basic-block.h"
37 #include "langhooks.h"
38 #include "diagnostic.h"
39 #include "tree-flow.h"
41 #include "tree-dump.h"
42 #include "tree-pass.h"
47 /* This file contains functions for building the Control Flow Graph (CFG)
48 for a function tree. */
50 /* Local declarations. */
52 /* Initial capacity for the basic block array. */
53 static const int initial_cfg_capacity
= 20;
55 /* Mapping of labels to their associated blocks. This can greatly speed up
56 building of the CFG in code with lots of gotos. */
57 static GTY(()) varray_type label_to_block_map
;
62 long num_merged_labels
;
65 static struct cfg_stats_d cfg_stats
;
67 /* Nonzero if we found a computed goto while building basic blocks. */
68 static bool found_computed_goto
;
70 /* Basic blocks and flowgraphs. */
71 static basic_block
create_bb (void *, void *, basic_block
);
72 static void create_block_annotation (basic_block
);
73 static void free_blocks_annotations (void);
74 static void clear_blocks_annotations (void);
75 static void make_blocks (tree
);
76 static void factor_computed_gotos (void);
77 static tree
tree_block_label (basic_block bb
);
80 static void make_edges (void);
81 static void make_ctrl_stmt_edges (basic_block
);
82 static void make_exit_edges (basic_block
);
83 static void make_cond_expr_edges (basic_block
);
84 static void make_switch_expr_edges (basic_block
);
85 static void make_goto_expr_edges (basic_block
);
86 static edge
tree_redirect_edge_and_branch (edge
, basic_block
);
87 static edge
tree_try_redirect_by_replacing_jump (edge
, basic_block
);
88 static void split_critical_edges (void);
90 /* Various helpers. */
91 static inline bool stmt_starts_bb_p (tree
, tree
);
92 static int tree_verify_flow_info (void);
93 static void tree_make_forwarder_block (edge
);
94 static bool thread_jumps (void);
95 static bool tree_forwarder_block_p (basic_block
);
96 static void bsi_commit_edge_inserts_1 (edge e
);
97 static void tree_cfg2vcg (FILE *);
99 /* Flowgraph optimization and cleanup. */
100 static void tree_merge_blocks (basic_block
, basic_block
);
101 static bool tree_can_merge_blocks_p (basic_block
, basic_block
);
102 static void remove_bb (basic_block
);
103 static void cleanup_dead_labels (void);
104 static bool cleanup_control_flow (void);
105 static bool cleanup_control_expr_graph (basic_block
, block_stmt_iterator
);
106 static edge
find_taken_edge_cond_expr (basic_block
, tree
);
107 static edge
find_taken_edge_switch_expr (basic_block
, tree
);
108 static tree
find_case_label_for_value (tree
, tree
);
109 static bool phi_alternatives_equal (basic_block
, edge
, edge
);
112 /*---------------------------------------------------------------------------
114 ---------------------------------------------------------------------------*/
116 /* Entry point to the CFG builder for trees. TP points to the list of
117 statements to be added to the flowgraph. */
120 build_tree_cfg (tree
*tp
)
122 /* Register specific tree functions. */
123 tree_register_cfg_hooks ();
125 /* Initialize rbi_pool. */
128 /* Initialize the basic block array. */
131 last_basic_block
= 0;
132 VARRAY_BB_INIT (basic_block_info
, initial_cfg_capacity
, "basic_block_info");
133 memset ((void *) &cfg_stats
, 0, sizeof (cfg_stats
));
135 /* Build a mapping of labels to their associated blocks. */
136 VARRAY_BB_INIT (label_to_block_map
, initial_cfg_capacity
,
137 "label to block map");
139 ENTRY_BLOCK_PTR
->next_bb
= EXIT_BLOCK_PTR
;
140 EXIT_BLOCK_PTR
->prev_bb
= ENTRY_BLOCK_PTR
;
142 found_computed_goto
= 0;
145 /* Computed gotos are hell to deal with, especially if there are
146 lots of them with a large number of destinations. So we factor
147 them to a common computed goto location before we build the
148 edge list. After we convert back to normal form, we will un-factor
149 the computed gotos since factoring introduces an unwanted jump. */
150 if (found_computed_goto
)
151 factor_computed_gotos ();
153 /* Make sure there is always at least one block, even if its empty. */
154 if (n_basic_blocks
== 0)
155 create_empty_bb (ENTRY_BLOCK_PTR
);
157 create_block_annotation (ENTRY_BLOCK_PTR
);
158 create_block_annotation (EXIT_BLOCK_PTR
);
160 /* Adjust the size of the array. */
161 VARRAY_GROW (basic_block_info
, n_basic_blocks
);
163 /* Create the edges of the flowgraph. */
166 /* Debugging dumps. */
168 /* Write the flowgraph to a VCG file. */
170 int local_dump_flags
;
171 FILE *dump_file
= dump_begin (TDI_vcg
, &local_dump_flags
);
174 tree_cfg2vcg (dump_file
);
175 dump_end (TDI_vcg
, dump_file
);
179 /* Dump a textual representation of the flowgraph. */
181 dump_tree_cfg (dump_file
, dump_flags
);
185 execute_build_cfg (void)
187 build_tree_cfg (&DECL_SAVED_TREE (current_function_decl
));
190 struct tree_opt_pass pass_build_cfg
=
194 execute_build_cfg
, /* execute */
197 0, /* static_pass_number */
198 TV_TREE_CFG
, /* tv_id */
199 PROP_gimple_leh
, /* properties_required */
200 PROP_cfg
, /* properties_provided */
201 0, /* properties_destroyed */
202 0, /* todo_flags_start */
203 TODO_verify_stmts
/* todo_flags_finish */
206 /* Search the CFG for any computed gotos. If found, factor them to a
207 common computed goto site. Also record the location of that site so
208 that we can un-factor the gotos after we have converted back to
212 factor_computed_gotos (void)
215 tree factored_label_decl
= NULL
;
217 tree factored_computed_goto_label
= NULL
;
218 tree factored_computed_goto
= NULL
;
220 /* We know there are one or more computed gotos in this function.
221 Examine the last statement in each basic block to see if the block
222 ends with a computed goto. */
226 block_stmt_iterator bsi
= bsi_last (bb
);
231 last
= bsi_stmt (bsi
);
233 /* Ignore the computed goto we create when we factor the original
235 if (last
== factored_computed_goto
)
238 /* If the last statement is a computed goto, factor it. */
239 if (computed_goto_p (last
))
243 /* The first time we find a computed goto we need to create
244 the factored goto block and the variable each original
245 computed goto will use for their goto destination. */
246 if (! factored_computed_goto
)
248 basic_block new_bb
= create_empty_bb (bb
);
249 block_stmt_iterator new_bsi
= bsi_start (new_bb
);
251 /* Create the destination of the factored goto. Each original
252 computed goto will put its desired destination into this
253 variable and jump to the label we create immediately
255 var
= create_tmp_var (ptr_type_node
, "gotovar");
257 /* Build a label for the new block which will contain the
258 factored computed goto. */
259 factored_label_decl
= create_artificial_label ();
260 factored_computed_goto_label
261 = build1 (LABEL_EXPR
, void_type_node
, factored_label_decl
);
262 bsi_insert_after (&new_bsi
, factored_computed_goto_label
,
265 /* Build our new computed goto. */
266 factored_computed_goto
= build1 (GOTO_EXPR
, void_type_node
, var
);
267 bsi_insert_after (&new_bsi
, factored_computed_goto
,
271 /* Copy the original computed goto's destination into VAR. */
272 assignment
= build (MODIFY_EXPR
, ptr_type_node
,
273 var
, GOTO_DESTINATION (last
));
274 bsi_insert_before (&bsi
, assignment
, BSI_SAME_STMT
);
276 /* And re-vector the computed goto to the new destination. */
277 GOTO_DESTINATION (last
) = factored_label_decl
;
283 /* Create annotations for a single basic block. */
286 create_block_annotation (basic_block bb
)
288 /* Verify that the tree_annotations field is clear. */
289 if (bb
->tree_annotations
)
291 bb
->tree_annotations
= ggc_alloc_cleared (sizeof (struct bb_ann_d
));
295 /* Free the annotations for all the basic blocks. */
297 static void free_blocks_annotations (void)
299 clear_blocks_annotations ();
303 /* Clear the annotations for all the basic blocks. */
306 clear_blocks_annotations (void)
310 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
, NULL
, next_bb
)
311 bb
->tree_annotations
= NULL
;
315 /* Build a flowgraph for the statement_list STMT_LIST. */
318 make_blocks (tree stmt_list
)
320 tree_stmt_iterator i
= tsi_start (stmt_list
);
322 bool start_new_block
= true;
323 bool first_stmt_of_list
= true;
324 basic_block bb
= ENTRY_BLOCK_PTR
;
326 while (!tsi_end_p (i
))
333 /* If the statement starts a new basic block or if we have determined
334 in a previous pass that we need to create a new block for STMT, do
336 if (start_new_block
|| stmt_starts_bb_p (stmt
, prev_stmt
))
338 if (!first_stmt_of_list
)
339 stmt_list
= tsi_split_statement_list_before (&i
);
340 bb
= create_basic_block (stmt_list
, NULL
, bb
);
341 start_new_block
= false;
344 /* Now add STMT to BB and create the subgraphs for special statement
346 set_bb_for_stmt (stmt
, bb
);
348 if (computed_goto_p (stmt
))
349 found_computed_goto
= true;
351 /* If STMT is a basic block terminator, set START_NEW_BLOCK for the
353 if (stmt_ends_bb_p (stmt
))
354 start_new_block
= true;
357 first_stmt_of_list
= false;
362 /* Create and return a new empty basic block after bb AFTER. */
365 create_bb (void *h
, void *e
, basic_block after
)
372 /* Create and initialize a new basic block. */
374 memset (bb
, 0, sizeof (*bb
));
376 bb
->index
= last_basic_block
;
378 bb
->stmt_list
= h
? h
: alloc_stmt_list ();
380 /* Add the new block to the linked list of blocks. */
381 link_block (bb
, after
);
383 /* Grow the basic block array if needed. */
384 if ((size_t) last_basic_block
== VARRAY_SIZE (basic_block_info
))
386 size_t new_size
= last_basic_block
+ (last_basic_block
+ 3) / 4;
387 VARRAY_GROW (basic_block_info
, new_size
);
390 /* Add the newly created block to the array. */
391 BASIC_BLOCK (last_basic_block
) = bb
;
393 create_block_annotation (bb
);
398 initialize_bb_rbi (bb
);
403 /*---------------------------------------------------------------------------
405 ---------------------------------------------------------------------------*/
407 /* Join all the blocks in the flowgraph. */
415 /* Create an edge from entry to the first block with executable
417 make_edge (ENTRY_BLOCK_PTR
, BASIC_BLOCK (0), EDGE_FALLTHRU
);
419 /* Traverse basic block array placing edges. */
422 tree first
= first_stmt (bb
);
423 tree last
= last_stmt (bb
);
427 /* Edges for statements that always alter flow control. */
428 if (is_ctrl_stmt (last
))
429 make_ctrl_stmt_edges (bb
);
431 /* Edges for statements that sometimes alter flow control. */
432 if (is_ctrl_altering_stmt (last
))
433 make_exit_edges (bb
);
436 /* Finally, if no edges were created above, this is a regular
437 basic block that only needs a fallthru edge. */
438 if (bb
->succ
== NULL
)
439 make_edge (bb
, bb
->next_bb
, EDGE_FALLTHRU
);
442 /* If there is a fallthru edge to exit out of the last block, transform it
443 to a return statement. */
444 for (e
= EXIT_BLOCK_PTR
->prev_bb
->succ
; e
; e
= e
->succ_next
)
445 if (e
->flags
& EDGE_FALLTHRU
)
448 if (e
&& e
->dest
== EXIT_BLOCK_PTR
)
450 block_stmt_iterator bsi
;
451 basic_block ret_bb
= EXIT_BLOCK_PTR
->prev_bb
;
454 /* If E->SRC ends with a call that has an abnormal edge (for EH or
455 nonlocal goto), then we will need to split the edge to insert
456 an explicit return statement. */
457 if (e
!= ret_bb
->succ
|| e
->succ_next
)
459 ret_bb
= split_edge (e
);
462 e
->flags
&= ~EDGE_FALLTHRU
;
464 x
= build (RETURN_EXPR
, void_type_node
, NULL_TREE
);
465 bsi
= bsi_last (ret_bb
);
466 bsi_insert_after (&bsi
, x
, BSI_NEW_STMT
);
469 /* We do not care about fake edges, so remove any that the CFG
470 builder inserted for completeness. */
471 remove_fake_edges ();
473 /* To speed up statement iterator walks, we first purge dead labels. */
474 cleanup_dead_labels ();
476 /* Clean up the graph and warn for unreachable code. */
481 /* Create edges for control statement at basic block BB. */
484 make_ctrl_stmt_edges (basic_block bb
)
486 tree last
= last_stmt (bb
);
487 tree first
= first_stmt (bb
);
489 #if defined ENABLE_CHECKING
490 if (last
== NULL_TREE
)
494 if (TREE_CODE (first
) == LABEL_EXPR
495 && DECL_NONLOCAL (LABEL_EXPR_LABEL (first
)))
496 make_edge (ENTRY_BLOCK_PTR
, bb
, EDGE_ABNORMAL
);
498 switch (TREE_CODE (last
))
501 make_goto_expr_edges (bb
);
505 make_edge (bb
, EXIT_BLOCK_PTR
, 0);
509 make_cond_expr_edges (bb
);
513 make_switch_expr_edges (bb
);
517 make_eh_edges (last
);
518 /* Yet another NORETURN hack. */
519 if (bb
->succ
== NULL
)
520 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
529 /* Create exit edges for statements in block BB that alter the flow of
530 control. Statements that alter the control flow are 'goto', 'return'
531 and calls to non-returning functions. */
534 make_exit_edges (basic_block bb
)
536 tree last
= last_stmt (bb
);
538 if (last
== NULL_TREE
)
541 switch (TREE_CODE (last
))
544 /* If this function receives a nonlocal goto, then we need to
545 make edges from this call site to all the nonlocal goto
547 if (TREE_SIDE_EFFECTS (last
)
548 && current_function_has_nonlocal_label
)
549 make_goto_expr_edges (bb
);
551 /* If this statement has reachable exception handlers, then
552 create abnormal edges to them. */
553 make_eh_edges (last
);
555 /* Some calls are known not to return. For such calls we create
558 We really need to revamp how we build edges so that it's not
559 such a bloody pain to avoid creating edges for this case since
560 all we do is remove these edges when we're done building the
562 if (call_expr_flags (last
) & (ECF_NORETURN
| ECF_LONGJMP
))
564 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
568 /* Don't forget the fall-thru edge. */
569 make_edge (bb
, bb
->next_bb
, EDGE_FALLTHRU
);
573 /* A MODIFY_EXPR may have a CALL_EXPR on its RHS and the CALL_EXPR
574 may have an abnormal edge. Search the RHS for this case and
575 create any required edges. */
576 if (TREE_CODE (TREE_OPERAND (last
, 1)) == CALL_EXPR
577 && TREE_SIDE_EFFECTS (TREE_OPERAND (last
, 1))
578 && current_function_has_nonlocal_label
)
579 make_goto_expr_edges (bb
);
581 make_eh_edges (last
);
582 make_edge (bb
, bb
->next_bb
, EDGE_FALLTHRU
);
591 /* Create the edges for a COND_EXPR starting at block BB.
592 At this point, both clauses must contain only simple gotos. */
595 make_cond_expr_edges (basic_block bb
)
597 tree entry
= last_stmt (bb
);
598 basic_block then_bb
, else_bb
;
599 tree then_label
, else_label
;
601 #if defined ENABLE_CHECKING
602 if (entry
== NULL_TREE
|| TREE_CODE (entry
) != COND_EXPR
)
606 /* Entry basic blocks for each component. */
607 then_label
= GOTO_DESTINATION (COND_EXPR_THEN (entry
));
608 else_label
= GOTO_DESTINATION (COND_EXPR_ELSE (entry
));
609 then_bb
= label_to_block (then_label
);
610 else_bb
= label_to_block (else_label
);
612 make_edge (bb
, then_bb
, EDGE_TRUE_VALUE
);
613 make_edge (bb
, else_bb
, EDGE_FALSE_VALUE
);
617 /* Create the edges for a SWITCH_EXPR starting at block BB.
618 At this point, the switch body has been lowered and the
619 SWITCH_LABELS filled in, so this is in effect a multi-way branch. */
622 make_switch_expr_edges (basic_block bb
)
624 tree entry
= last_stmt (bb
);
628 vec
= SWITCH_LABELS (entry
);
629 n
= TREE_VEC_LENGTH (vec
);
631 for (i
= 0; i
< n
; ++i
)
633 tree lab
= CASE_LABEL (TREE_VEC_ELT (vec
, i
));
634 basic_block label_bb
= label_to_block (lab
);
635 make_edge (bb
, label_bb
, 0);
640 /* Return the basic block holding label DEST. */
643 label_to_block (tree dest
)
645 return VARRAY_BB (label_to_block_map
, LABEL_DECL_UID (dest
));
649 /* Create edges for a goto statement at block BB. */
652 make_goto_expr_edges (basic_block bb
)
655 basic_block target_bb
;
657 block_stmt_iterator last
= bsi_last (bb
);
659 goto_t
= bsi_stmt (last
);
661 /* If the last statement is not a GOTO (i.e., it is a RETURN_EXPR,
662 CALL_EXPR or MODIFY_EXPR), then the edge is an abnormal edge resulting
663 from a nonlocal goto. */
664 if (TREE_CODE (goto_t
) != GOTO_EXPR
)
666 dest
= error_mark_node
;
671 dest
= GOTO_DESTINATION (goto_t
);
674 /* A GOTO to a local label creates normal edges. */
675 if (simple_goto_p (goto_t
))
677 make_edge (bb
, label_to_block (dest
), EDGE_FALLTHRU
);
682 /* Nothing more to do for nonlocal gotos. */
683 if (TREE_CODE (dest
) == LABEL_DECL
)
686 /* Computed gotos remain. */
689 /* Look for the block starting with the destination label. In the
690 case of a computed goto, make an edge to any label block we find
692 FOR_EACH_BB (target_bb
)
694 block_stmt_iterator bsi
;
696 for (bsi
= bsi_start (target_bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
698 tree target
= bsi_stmt (bsi
);
700 if (TREE_CODE (target
) != LABEL_EXPR
)
704 /* Computed GOTOs. Make an edge to every label block that has
705 been marked as a potential target for a computed goto. */
706 (FORCED_LABEL (LABEL_EXPR_LABEL (target
)) && for_call
== 0)
707 /* Nonlocal GOTO target. Make an edge to every label block
708 that has been marked as a potential target for a nonlocal
710 || (DECL_NONLOCAL (LABEL_EXPR_LABEL (target
)) && for_call
== 1))
712 make_edge (bb
, target_bb
, EDGE_ABNORMAL
);
718 /* Degenerate case of computed goto with no labels. */
719 if (!for_call
&& !bb
->succ
)
720 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
724 /*---------------------------------------------------------------------------
726 ---------------------------------------------------------------------------*/
728 /* Remove unreachable blocks and other miscellaneous clean up work. */
731 cleanup_tree_cfg (void)
733 bool something_changed
= true;
735 timevar_push (TV_TREE_CLEANUP_CFG
);
737 /* These three transformations can cascade, so we iterate on them until
739 while (something_changed
)
741 something_changed
= cleanup_control_flow ();
742 something_changed
|= thread_jumps ();
743 something_changed
|= delete_unreachable_blocks ();
746 /* Merging the blocks creates no new opportunities for the other
747 optimizations, so do it here. */
752 #ifdef ENABLE_CHECKING
755 timevar_pop (TV_TREE_CLEANUP_CFG
);
759 /* Cleanup useless labels from the flow graph. */
762 cleanup_dead_labels (void)
765 tree
*label_for_bb
= xcalloc (last_basic_block
, sizeof (tree
));
767 /* Find a suitable label for each block. We use the first user-defined
768 label is there is one, or otherwise just the first label we see. */
771 block_stmt_iterator i
;
773 for (i
= bsi_start (bb
); !bsi_end_p (i
); bsi_next (&i
))
775 tree label
, stmt
= bsi_stmt (i
);
777 if (TREE_CODE (stmt
) != LABEL_EXPR
)
780 label
= LABEL_EXPR_LABEL (stmt
);
782 /* If we have not yet seen a label for the current block,
783 remember this one and see if there are more labels. */
784 if (! label_for_bb
[bb
->index
])
786 label_for_bb
[bb
->index
] = label
;
790 /* If we did see a label for the current block already, but it
791 is an artificially created label, replace it if the current
792 label is a user defined label. */
793 if (! DECL_ARTIFICIAL (label
)
794 && DECL_ARTIFICIAL (label_for_bb
[bb
->index
]))
796 label_for_bb
[bb
->index
] = label
;
802 /* Now redirect all jumps/branches to the selected label for each block. */
805 tree stmt
= last_stmt (bb
);
809 switch (TREE_CODE (stmt
))
813 tree true_branch
, false_branch
;
814 basic_block true_bb
, false_bb
;
816 true_branch
= COND_EXPR_THEN (stmt
);
817 false_branch
= COND_EXPR_ELSE (stmt
);
818 true_bb
= label_to_block (GOTO_DESTINATION (true_branch
));
819 false_bb
= label_to_block (GOTO_DESTINATION (false_branch
));
821 GOTO_DESTINATION (true_branch
) = label_for_bb
[true_bb
->index
];
822 GOTO_DESTINATION (false_branch
) = label_for_bb
[false_bb
->index
];
830 tree vec
= SWITCH_LABELS (stmt
);
831 size_t n
= TREE_VEC_LENGTH (vec
);
833 /* Replace all destination labels. */
834 for (i
= 0; i
< n
; ++i
)
836 tree label
= CASE_LABEL (TREE_VEC_ELT (vec
, i
));
838 CASE_LABEL (TREE_VEC_ELT (vec
, i
)) =
839 label_for_bb
[label_to_block (label
)->index
];
850 /* Finally, purge dead labels. All user-defined labels and labels that
851 can be the target of non-local gotos are preserved. */
854 block_stmt_iterator i
;
855 tree label_for_this_bb
= label_for_bb
[bb
->index
];
857 if (! label_for_this_bb
)
860 for (i
= bsi_start (bb
); !bsi_end_p (i
); )
862 tree label
, stmt
= bsi_stmt (i
);
864 if (TREE_CODE (stmt
) != LABEL_EXPR
)
867 label
= LABEL_EXPR_LABEL (stmt
);
869 if (label
== label_for_this_bb
870 || ! DECL_ARTIFICIAL (label
)
871 || DECL_NONLOCAL (label
))
882 /* Checks whether we can merge block B into block A. */
885 tree_can_merge_blocks_p (basic_block a
, basic_block b
)
888 block_stmt_iterator bsi
;
891 || a
->succ
->succ_next
)
894 if (a
->succ
->flags
& EDGE_ABNORMAL
)
897 if (a
->succ
->dest
!= b
)
900 if (b
== EXIT_BLOCK_PTR
)
903 if (b
->pred
->pred_next
)
906 /* If A ends by a statement causing exceptions or something similar, we
907 cannot merge the blocks. */
908 stmt
= last_stmt (a
);
909 if (stmt
&& stmt_ends_bb_p (stmt
))
912 /* Do not allow a block with only a non-local label to be merged. */
913 if (stmt
&& TREE_CODE (stmt
) == LABEL_EXPR
914 && DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt
)))
917 /* There may be no phi nodes at the start of b. Most of these degenerate
918 phi nodes should be cleaned up by kill_redundant_phi_nodes. */
922 /* Do not remove user labels. */
923 for (bsi
= bsi_start (b
); !bsi_end_p (bsi
); bsi_next (&bsi
))
925 stmt
= bsi_stmt (bsi
);
926 if (TREE_CODE (stmt
) != LABEL_EXPR
)
928 if (!DECL_ARTIFICIAL (LABEL_EXPR_LABEL (stmt
)))
936 /* Merge block B into block A. */
939 tree_merge_blocks (basic_block a
, basic_block b
)
941 block_stmt_iterator bsi
;
942 tree_stmt_iterator last
;
945 fprintf (dump_file
, "Merging blocks %d and %d\n", a
->index
, b
->index
);
947 /* Ensure that B follows A. */
948 move_block_after (b
, a
);
950 if (!(a
->succ
->flags
& EDGE_FALLTHRU
))
954 && stmt_ends_bb_p (last_stmt (a
)))
957 /* Remove labels from B and set bb_for_stmt to A for other statements. */
958 for (bsi
= bsi_start (b
); !bsi_end_p (bsi
);)
960 if (TREE_CODE (bsi_stmt (bsi
)) == LABEL_EXPR
)
964 set_bb_for_stmt (bsi_stmt (bsi
), a
);
969 /* Merge the chains. */
970 last
= tsi_last (a
->stmt_list
);
971 tsi_link_after (&last
, b
->stmt_list
, TSI_NEW_STMT
);
976 /* Walk the function tree removing unnecessary statements.
978 * Empty statement nodes are removed
980 * Unnecessary TRY_FINALLY and TRY_CATCH blocks are removed
982 * Unnecessary COND_EXPRs are removed
984 * Some unnecessary BIND_EXPRs are removed
986 Clearly more work could be done. The trick is doing the analysis
987 and removal fast enough to be a net improvement in compile times.
989 Note that when we remove a control structure such as a COND_EXPR
990 BIND_EXPR, or TRY block, we will need to repeat this optimization pass
991 to ensure we eliminate all the useless code. */
1002 static void remove_useless_stmts_1 (tree
*, struct rus_data
*);
1005 remove_useless_stmts_warn_notreached (tree stmt
)
1007 if (EXPR_LOCUS (stmt
))
1009 warning ("%Hwill never be executed", EXPR_LOCUS (stmt
));
1013 switch (TREE_CODE (stmt
))
1015 case STATEMENT_LIST
:
1017 tree_stmt_iterator i
;
1018 for (i
= tsi_start (stmt
); !tsi_end_p (i
); tsi_next (&i
))
1019 if (remove_useless_stmts_warn_notreached (tsi_stmt (i
)))
1025 if (remove_useless_stmts_warn_notreached (COND_EXPR_COND (stmt
)))
1027 if (remove_useless_stmts_warn_notreached (COND_EXPR_THEN (stmt
)))
1029 if (remove_useless_stmts_warn_notreached (COND_EXPR_ELSE (stmt
)))
1033 case TRY_FINALLY_EXPR
:
1034 case TRY_CATCH_EXPR
:
1035 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt
, 0)))
1037 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt
, 1)))
1042 return remove_useless_stmts_warn_notreached (CATCH_BODY (stmt
));
1043 case EH_FILTER_EXPR
:
1044 return remove_useless_stmts_warn_notreached (EH_FILTER_FAILURE (stmt
));
1046 return remove_useless_stmts_warn_notreached (BIND_EXPR_BLOCK (stmt
));
1049 /* Not a live container. */
1057 remove_useless_stmts_cond (tree
*stmt_p
, struct rus_data
*data
)
1059 tree then_clause
, else_clause
, cond
;
1060 bool save_has_label
, then_has_label
, else_has_label
;
1062 save_has_label
= data
->has_label
;
1063 data
->has_label
= false;
1064 data
->last_goto
= NULL
;
1066 remove_useless_stmts_1 (&COND_EXPR_THEN (*stmt_p
), data
);
1068 then_has_label
= data
->has_label
;
1069 data
->has_label
= false;
1070 data
->last_goto
= NULL
;
1072 remove_useless_stmts_1 (&COND_EXPR_ELSE (*stmt_p
), data
);
1074 else_has_label
= data
->has_label
;
1075 data
->has_label
= save_has_label
| then_has_label
| else_has_label
;
1078 then_clause
= COND_EXPR_THEN (*stmt_p
);
1079 else_clause
= COND_EXPR_ELSE (*stmt_p
);
1080 cond
= COND_EXPR_COND (*stmt_p
);
1082 /* If neither arm does anything at all, we can remove the whole IF. */
1083 if (!TREE_SIDE_EFFECTS (then_clause
) && !TREE_SIDE_EFFECTS (else_clause
))
1085 *stmt_p
= build_empty_stmt ();
1086 data
->repeat
= true;
1089 /* If there are no reachable statements in an arm, then we can
1090 zap the entire conditional. */
1091 else if (integer_nonzerop (cond
) && !else_has_label
)
1093 if (warn_notreached
)
1094 remove_useless_stmts_warn_notreached (else_clause
);
1095 *stmt_p
= then_clause
;
1096 data
->repeat
= true;
1098 else if (integer_zerop (cond
) && !then_has_label
)
1100 if (warn_notreached
)
1101 remove_useless_stmts_warn_notreached (then_clause
);
1102 *stmt_p
= else_clause
;
1103 data
->repeat
= true;
1106 /* Check a couple of simple things on then/else with single stmts. */
1109 tree then_stmt
= expr_only (then_clause
);
1110 tree else_stmt
= expr_only (else_clause
);
1112 /* Notice branches to a common destination. */
1113 if (then_stmt
&& else_stmt
1114 && TREE_CODE (then_stmt
) == GOTO_EXPR
1115 && TREE_CODE (else_stmt
) == GOTO_EXPR
1116 && (GOTO_DESTINATION (then_stmt
) == GOTO_DESTINATION (else_stmt
)))
1118 *stmt_p
= then_stmt
;
1119 data
->repeat
= true;
1122 /* If the THEN/ELSE clause merely assigns a value to a variable or
1123 parameter which is already known to contain that value, then
1124 remove the useless THEN/ELSE clause. */
1125 else if (TREE_CODE (cond
) == VAR_DECL
|| TREE_CODE (cond
) == PARM_DECL
)
1128 && TREE_CODE (else_stmt
) == MODIFY_EXPR
1129 && TREE_OPERAND (else_stmt
, 0) == cond
1130 && integer_zerop (TREE_OPERAND (else_stmt
, 1)))
1131 COND_EXPR_ELSE (*stmt_p
) = alloc_stmt_list ();
1133 else if ((TREE_CODE (cond
) == EQ_EXPR
|| TREE_CODE (cond
) == NE_EXPR
)
1134 && (TREE_CODE (TREE_OPERAND (cond
, 0)) == VAR_DECL
1135 || TREE_CODE (TREE_OPERAND (cond
, 0)) == PARM_DECL
)
1136 && TREE_CONSTANT (TREE_OPERAND (cond
, 1)))
1138 tree stmt
= (TREE_CODE (cond
) == EQ_EXPR
1139 ? then_stmt
: else_stmt
);
1140 tree
*location
= (TREE_CODE (cond
) == EQ_EXPR
1141 ? &COND_EXPR_THEN (*stmt_p
)
1142 : &COND_EXPR_ELSE (*stmt_p
));
1145 && TREE_CODE (stmt
) == MODIFY_EXPR
1146 && TREE_OPERAND (stmt
, 0) == TREE_OPERAND (cond
, 0)
1147 && TREE_OPERAND (stmt
, 1) == TREE_OPERAND (cond
, 1))
1148 *location
= alloc_stmt_list ();
1152 /* Protect GOTOs in the arm of COND_EXPRs from being removed. They
1153 would be re-introduced during lowering. */
1154 data
->last_goto
= NULL
;
1159 remove_useless_stmts_tf (tree
*stmt_p
, struct rus_data
*data
)
1161 bool save_may_branch
, save_may_throw
;
1162 bool this_may_branch
, this_may_throw
;
1164 /* Collect may_branch and may_throw information for the body only. */
1165 save_may_branch
= data
->may_branch
;
1166 save_may_throw
= data
->may_throw
;
1167 data
->may_branch
= false;
1168 data
->may_throw
= false;
1169 data
->last_goto
= NULL
;
1171 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p
, 0), data
);
1173 this_may_branch
= data
->may_branch
;
1174 this_may_throw
= data
->may_throw
;
1175 data
->may_branch
|= save_may_branch
;
1176 data
->may_throw
|= save_may_throw
;
1177 data
->last_goto
= NULL
;
1179 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p
, 1), data
);
1181 /* If the body is empty, then we can emit the FINALLY block without
1182 the enclosing TRY_FINALLY_EXPR. */
1183 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p
, 0)))
1185 *stmt_p
= TREE_OPERAND (*stmt_p
, 1);
1186 data
->repeat
= true;
1189 /* If the handler is empty, then we can emit the TRY block without
1190 the enclosing TRY_FINALLY_EXPR. */
1191 else if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p
, 1)))
1193 *stmt_p
= TREE_OPERAND (*stmt_p
, 0);
1194 data
->repeat
= true;
1197 /* If the body neither throws, nor branches, then we can safely
1198 string the TRY and FINALLY blocks together. */
1199 else if (!this_may_branch
&& !this_may_throw
)
1201 tree stmt
= *stmt_p
;
1202 *stmt_p
= TREE_OPERAND (stmt
, 0);
1203 append_to_statement_list (TREE_OPERAND (stmt
, 1), stmt_p
);
1204 data
->repeat
= true;
1210 remove_useless_stmts_tc (tree
*stmt_p
, struct rus_data
*data
)
1212 bool save_may_throw
, this_may_throw
;
1213 tree_stmt_iterator i
;
1216 /* Collect may_throw information for the body only. */
1217 save_may_throw
= data
->may_throw
;
1218 data
->may_throw
= false;
1219 data
->last_goto
= NULL
;
1221 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p
, 0), data
);
1223 this_may_throw
= data
->may_throw
;
1224 data
->may_throw
= save_may_throw
;
1226 /* If the body cannot throw, then we can drop the entire TRY_CATCH_EXPR. */
1227 if (!this_may_throw
)
1229 if (warn_notreached
)
1230 remove_useless_stmts_warn_notreached (TREE_OPERAND (*stmt_p
, 1));
1231 *stmt_p
= TREE_OPERAND (*stmt_p
, 0);
1232 data
->repeat
= true;
1236 /* Process the catch clause specially. We may be able to tell that
1237 no exceptions propagate past this point. */
1239 this_may_throw
= true;
1240 i
= tsi_start (TREE_OPERAND (*stmt_p
, 1));
1241 stmt
= tsi_stmt (i
);
1242 data
->last_goto
= NULL
;
1244 switch (TREE_CODE (stmt
))
1247 for (; !tsi_end_p (i
); tsi_next (&i
))
1249 stmt
= tsi_stmt (i
);
1250 /* If we catch all exceptions, then the body does not
1251 propagate exceptions past this point. */
1252 if (CATCH_TYPES (stmt
) == NULL
)
1253 this_may_throw
= false;
1254 data
->last_goto
= NULL
;
1255 remove_useless_stmts_1 (&CATCH_BODY (stmt
), data
);
1259 case EH_FILTER_EXPR
:
1260 if (EH_FILTER_MUST_NOT_THROW (stmt
))
1261 this_may_throw
= false;
1262 else if (EH_FILTER_TYPES (stmt
) == NULL
)
1263 this_may_throw
= false;
1264 remove_useless_stmts_1 (&EH_FILTER_FAILURE (stmt
), data
);
1268 /* Otherwise this is a cleanup. */
1269 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p
, 1), data
);
1271 /* If the cleanup is empty, then we can emit the TRY block without
1272 the enclosing TRY_CATCH_EXPR. */
1273 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p
, 1)))
1275 *stmt_p
= TREE_OPERAND (*stmt_p
, 0);
1276 data
->repeat
= true;
1280 data
->may_throw
|= this_may_throw
;
1285 remove_useless_stmts_bind (tree
*stmt_p
, struct rus_data
*data
)
1289 /* First remove anything underneath the BIND_EXPR. */
1290 remove_useless_stmts_1 (&BIND_EXPR_BODY (*stmt_p
), data
);
1292 /* If the BIND_EXPR has no variables, then we can pull everything
1293 up one level and remove the BIND_EXPR, unless this is the toplevel
1294 BIND_EXPR for the current function or an inlined function.
1296 When this situation occurs we will want to apply this
1297 optimization again. */
1298 block
= BIND_EXPR_BLOCK (*stmt_p
);
1299 if (BIND_EXPR_VARS (*stmt_p
) == NULL_TREE
1300 && *stmt_p
!= DECL_SAVED_TREE (current_function_decl
)
1302 || ! BLOCK_ABSTRACT_ORIGIN (block
)
1303 || (TREE_CODE (BLOCK_ABSTRACT_ORIGIN (block
))
1306 *stmt_p
= BIND_EXPR_BODY (*stmt_p
);
1307 data
->repeat
= true;
1313 remove_useless_stmts_goto (tree
*stmt_p
, struct rus_data
*data
)
1315 tree dest
= GOTO_DESTINATION (*stmt_p
);
1317 data
->may_branch
= true;
1318 data
->last_goto
= NULL
;
1320 /* Record the last goto expr, so that we can delete it if unnecessary. */
1321 if (TREE_CODE (dest
) == LABEL_DECL
)
1322 data
->last_goto
= stmt_p
;
1327 remove_useless_stmts_label (tree
*stmt_p
, struct rus_data
*data
)
1329 tree label
= LABEL_EXPR_LABEL (*stmt_p
);
1331 data
->has_label
= true;
1333 /* We do want to jump across non-local label receiver code. */
1334 if (DECL_NONLOCAL (label
))
1335 data
->last_goto
= NULL
;
1337 else if (data
->last_goto
&& GOTO_DESTINATION (*data
->last_goto
) == label
)
1339 *data
->last_goto
= build_empty_stmt ();
1340 data
->repeat
= true;
1343 /* ??? Add something here to delete unused labels. */
1347 /* If the function is "const" or "pure", then clear TREE_SIDE_EFFECTS on its
1348 decl. This allows us to eliminate redundant or useless
1349 calls to "const" functions.
1351 Gimplifier already does the same operation, but we may notice functions
1352 being const and pure once their calls has been gimplified, so we need
1353 to update the flag. */
1356 update_call_expr_flags (tree call
)
1358 tree decl
= get_callee_fndecl (call
);
1361 if (call_expr_flags (call
) & (ECF_CONST
| ECF_PURE
))
1362 TREE_SIDE_EFFECTS (call
) = 0;
1363 if (TREE_NOTHROW (decl
))
1364 TREE_NOTHROW (call
) = 1;
1368 /* T is CALL_EXPR. Set current_function_calls_* flags. */
1371 notice_special_calls (tree t
)
1373 int flags
= call_expr_flags (t
);
1375 if (flags
& ECF_MAY_BE_ALLOCA
)
1376 current_function_calls_alloca
= true;
1377 if (flags
& ECF_RETURNS_TWICE
)
1378 current_function_calls_setjmp
= true;
1382 /* Clear flags set by notice_special_calls. Used by dead code removal
1383 to update the flags. */
1386 clear_special_calls (void)
1388 current_function_calls_alloca
= false;
1389 current_function_calls_setjmp
= false;
1394 remove_useless_stmts_1 (tree
*tp
, struct rus_data
*data
)
1398 switch (TREE_CODE (t
))
1401 remove_useless_stmts_cond (tp
, data
);
1404 case TRY_FINALLY_EXPR
:
1405 remove_useless_stmts_tf (tp
, data
);
1408 case TRY_CATCH_EXPR
:
1409 remove_useless_stmts_tc (tp
, data
);
1413 remove_useless_stmts_bind (tp
, data
);
1417 remove_useless_stmts_goto (tp
, data
);
1421 remove_useless_stmts_label (tp
, data
);
1426 data
->last_goto
= NULL
;
1427 data
->may_branch
= true;
1432 data
->last_goto
= NULL
;
1433 notice_special_calls (t
);
1434 update_call_expr_flags (t
);
1435 if (tree_could_throw_p (t
))
1436 data
->may_throw
= true;
1440 data
->last_goto
= NULL
;
1442 if (TREE_CODE (TREE_OPERAND (t
, 1)) == CALL_EXPR
)
1444 update_call_expr_flags (TREE_OPERAND (t
, 1));
1445 notice_special_calls (TREE_OPERAND (t
, 1));
1447 if (tree_could_throw_p (t
))
1448 data
->may_throw
= true;
1451 case STATEMENT_LIST
:
1453 tree_stmt_iterator i
= tsi_start (t
);
1454 while (!tsi_end_p (i
))
1457 if (IS_EMPTY_STMT (t
))
1463 remove_useless_stmts_1 (tsi_stmt_ptr (i
), data
);
1466 if (TREE_CODE (t
) == STATEMENT_LIST
)
1468 tsi_link_before (&i
, t
, TSI_SAME_STMT
);
1478 data
->last_goto
= NULL
;
1482 data
->last_goto
= NULL
;
1488 remove_useless_stmts (void)
1490 struct rus_data data
;
1492 clear_special_calls ();
1496 memset (&data
, 0, sizeof (data
));
1497 remove_useless_stmts_1 (&DECL_SAVED_TREE (current_function_decl
), &data
);
1499 while (data
.repeat
);
1503 struct tree_opt_pass pass_remove_useless_stmts
=
1505 "useless", /* name */
1507 remove_useless_stmts
, /* execute */
1510 0, /* static_pass_number */
1512 PROP_gimple_any
, /* properties_required */
1513 0, /* properties_provided */
1514 0, /* properties_destroyed */
1515 0, /* todo_flags_start */
1516 TODO_dump_func
/* todo_flags_finish */
1520 /* Remove obviously useless statements in basic block BB. */
1523 cfg_remove_useless_stmts_bb (basic_block bb
)
1525 block_stmt_iterator bsi
;
1526 tree stmt
= NULL_TREE
;
1527 tree cond
, var
= NULL_TREE
, val
= NULL_TREE
;
1528 struct var_ann_d
*ann
;
1530 /* Check whether we come here from a condition, and if so, get the
1533 || bb
->pred
->pred_next
1534 || !(bb
->pred
->flags
& (EDGE_TRUE_VALUE
| EDGE_FALSE_VALUE
)))
1537 cond
= COND_EXPR_COND (last_stmt (bb
->pred
->src
));
1539 if (TREE_CODE (cond
) == VAR_DECL
|| TREE_CODE (cond
) == PARM_DECL
)
1542 val
= (bb
->pred
->flags
& EDGE_FALSE_VALUE
1543 ? boolean_false_node
: boolean_true_node
);
1545 else if (TREE_CODE (cond
) == TRUTH_NOT_EXPR
1546 && (TREE_CODE (TREE_OPERAND (cond
, 0)) == VAR_DECL
1547 || TREE_CODE (TREE_OPERAND (cond
, 0)) == PARM_DECL
))
1549 var
= TREE_OPERAND (cond
, 0);
1550 val
= (bb
->pred
->flags
& EDGE_FALSE_VALUE
1551 ? boolean_true_node
: boolean_false_node
);
1555 if (bb
->pred
->flags
& EDGE_FALSE_VALUE
)
1556 cond
= invert_truthvalue (cond
);
1557 if (TREE_CODE (cond
) == EQ_EXPR
1558 && (TREE_CODE (TREE_OPERAND (cond
, 0)) == VAR_DECL
1559 || TREE_CODE (TREE_OPERAND (cond
, 0)) == PARM_DECL
)
1560 && (TREE_CODE (TREE_OPERAND (cond
, 1)) == VAR_DECL
1561 || TREE_CODE (TREE_OPERAND (cond
, 1)) == PARM_DECL
1562 || TREE_CONSTANT (TREE_OPERAND (cond
, 1))))
1564 var
= TREE_OPERAND (cond
, 0);
1565 val
= TREE_OPERAND (cond
, 1);
1571 /* Only work for normal local variables. */
1572 ann
= var_ann (var
);
1575 || TREE_ADDRESSABLE (var
))
1578 if (! TREE_CONSTANT (val
))
1580 ann
= var_ann (val
);
1583 || TREE_ADDRESSABLE (val
))
1587 /* Ignore floating point variables, since comparison behaves weird for
1589 if (FLOAT_TYPE_P (TREE_TYPE (var
)))
1592 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
);)
1594 stmt
= bsi_stmt (bsi
);
1596 /* If the THEN/ELSE clause merely assigns a value to a variable/parameter
1597 which is already known to contain that value, then remove the useless
1598 THEN/ELSE clause. */
1599 if (TREE_CODE (stmt
) == MODIFY_EXPR
1600 && TREE_OPERAND (stmt
, 0) == var
1601 && operand_equal_p (val
, TREE_OPERAND (stmt
, 1), 0))
1607 /* Invalidate the var if we encounter something that could modify it. */
1608 if (TREE_CODE (stmt
) == ASM_EXPR
1609 || TREE_CODE (stmt
) == VA_ARG_EXPR
1610 || (TREE_CODE (stmt
) == MODIFY_EXPR
1611 && (TREE_OPERAND (stmt
, 0) == var
1612 || TREE_OPERAND (stmt
, 0) == val
1613 || TREE_CODE (TREE_OPERAND (stmt
, 1)) == VA_ARG_EXPR
)))
1621 /* A CFG-aware version of remove_useless_stmts. */
1624 cfg_remove_useless_stmts (void)
1628 #ifdef ENABLE_CHECKING
1629 verify_flow_info ();
1634 cfg_remove_useless_stmts_bb (bb
);
1639 /* Remove PHI nodes associated with basic block BB and all edges out of BB. */
1642 remove_phi_nodes_and_edges_for_unreachable_block (basic_block bb
)
1646 /* Since this block is no longer reachable, we can just delete all
1647 of its PHI nodes. */
1648 phi
= phi_nodes (bb
);
1651 tree next
= TREE_CHAIN (phi
);
1652 remove_phi_node (phi
, NULL_TREE
, bb
);
1656 /* Remove edges to BB's successors. */
1657 while (bb
->succ
!= NULL
)
1658 ssa_remove_edge (bb
->succ
);
1662 /* Remove statements of basic block BB. */
1665 remove_bb (basic_block bb
)
1667 block_stmt_iterator i
;
1668 location_t
*loc
= NULL
;
1672 fprintf (dump_file
, "Removing basic block %d\n", bb
->index
);
1673 if (dump_flags
& TDF_DETAILS
)
1675 dump_bb (bb
, dump_file
, 0);
1676 fprintf (dump_file
, "\n");
1680 /* Remove all the instructions in the block. */
1681 for (i
= bsi_start (bb
); !bsi_end_p (i
); bsi_remove (&i
))
1683 tree stmt
= bsi_stmt (i
);
1685 set_bb_for_stmt (stmt
, NULL
);
1687 /* Don't warn for removed gotos. Gotos are often removed due to
1688 jump threading, thus resulting in bogus warnings. Not great,
1689 since this way we lose warnings for gotos in the original
1690 program that are indeed unreachable. */
1691 if (TREE_CODE (stmt
) != GOTO_EXPR
&& EXPR_LOCUS (stmt
) && !loc
)
1692 loc
= EXPR_LOCUS (stmt
);
1695 /* If requested, give a warning that the first statement in the
1696 block is unreachable. We walk statements backwards in the
1697 loop above, so the last statement we process is the first statement
1699 if (warn_notreached
&& loc
)
1700 warning ("%Hwill never be executed", loc
);
1702 remove_phi_nodes_and_edges_for_unreachable_block (bb
);
1706 /* Examine BB to determine if it is a forwarding block (a block which only
1707 transfers control to a new destination). If BB is a forwarding block,
1708 then return the edge leading to the ultimate destination. */
1711 tree_block_forwards_to (basic_block bb
)
1713 block_stmt_iterator bsi
;
1714 bb_ann_t ann
= bb_ann (bb
);
1717 /* If this block is not forwardable, then avoid useless work. */
1718 if (! ann
->forwardable
)
1721 /* Set this block to not be forwardable. This prevents infinite loops since
1722 any block currently under examination is considered non-forwardable. */
1723 ann
->forwardable
= 0;
1725 /* No forwarding is possible if this block is a special block (ENTRY/EXIT),
1726 this block has more than one successor, this block's single successor is
1727 reached via an abnormal edge, this block has phi nodes, or this block's
1728 single successor has phi nodes. */
1729 if (bb
== EXIT_BLOCK_PTR
1730 || bb
== ENTRY_BLOCK_PTR
1732 || bb
->succ
->succ_next
1733 || bb
->succ
->dest
== EXIT_BLOCK_PTR
1734 || (bb
->succ
->flags
& EDGE_ABNORMAL
) != 0
1736 || phi_nodes (bb
->succ
->dest
))
1739 /* Walk past any labels at the start of this block. */
1740 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
1742 stmt
= bsi_stmt (bsi
);
1743 if (TREE_CODE (stmt
) != LABEL_EXPR
)
1747 /* If we reached the end of this block we may be able to optimize this
1749 if (bsi_end_p (bsi
))
1753 /* Recursive call to pick up chains of forwarding blocks. */
1754 dest
= tree_block_forwards_to (bb
->succ
->dest
);
1756 /* If none found, we forward to bb->succ at minimum. */
1760 ann
->forwardable
= 1;
1764 /* No forwarding possible. */
1769 /* Try to remove superfluous control structures. */
1772 cleanup_control_flow (void)
1775 block_stmt_iterator bsi
;
1776 bool retval
= false;
1781 bsi
= bsi_last (bb
);
1783 if (bsi_end_p (bsi
))
1786 stmt
= bsi_stmt (bsi
);
1787 if (TREE_CODE (stmt
) == COND_EXPR
1788 || TREE_CODE (stmt
) == SWITCH_EXPR
)
1789 retval
|= cleanup_control_expr_graph (bb
, bsi
);
1795 /* Disconnect an unreachable block in the control expression starting
1799 cleanup_control_expr_graph (basic_block bb
, block_stmt_iterator bsi
)
1802 bool retval
= false;
1803 tree expr
= bsi_stmt (bsi
), val
;
1805 if (bb
->succ
->succ_next
)
1809 switch (TREE_CODE (expr
))
1812 val
= COND_EXPR_COND (expr
);
1816 val
= SWITCH_COND (expr
);
1817 if (TREE_CODE (val
) != INTEGER_CST
)
1825 taken_edge
= find_taken_edge (bb
, val
);
1829 /* Remove all the edges except the one that is always executed. */
1830 for (e
= bb
->succ
; e
; e
= next
)
1832 next
= e
->succ_next
;
1833 if (e
!= taken_edge
)
1835 taken_edge
->probability
+= e
->probability
;
1836 taken_edge
->count
+= e
->count
;
1837 ssa_remove_edge (e
);
1841 if (taken_edge
->probability
> REG_BR_PROB_BASE
)
1842 taken_edge
->probability
= REG_BR_PROB_BASE
;
1845 taken_edge
= bb
->succ
;
1848 taken_edge
->flags
= EDGE_FALLTHRU
;
1850 /* We removed some paths from the cfg. */
1851 if (dom_computed
[CDI_DOMINATORS
] >= DOM_CONS_OK
)
1852 dom_computed
[CDI_DOMINATORS
] = DOM_CONS_OK
;
1858 /* Given a control block BB and a constant value VAL, return the edge that
1859 will be taken out of the block. If VAL does not match a unique edge,
1860 NULL is returned. */
1863 find_taken_edge (basic_block bb
, tree val
)
1867 stmt
= last_stmt (bb
);
1869 #if defined ENABLE_CHECKING
1870 if (stmt
== NULL_TREE
|| !is_ctrl_stmt (stmt
))
1874 /* If VAL is not a constant, we can't determine which edge might
1876 if (val
== NULL
|| !really_constant_p (val
))
1879 if (TREE_CODE (stmt
) == COND_EXPR
)
1880 return find_taken_edge_cond_expr (bb
, val
);
1882 if (TREE_CODE (stmt
) == SWITCH_EXPR
)
1883 return find_taken_edge_switch_expr (bb
, val
);
1889 /* Given a constant value VAL and the entry block BB to a COND_EXPR
1890 statement, determine which of the two edges will be taken out of the
1891 block. Return NULL if either edge may be taken. */
1894 find_taken_edge_cond_expr (basic_block bb
, tree val
)
1896 edge true_edge
, false_edge
;
1898 extract_true_false_edges_from_block (bb
, &true_edge
, &false_edge
);
1900 /* If both edges of the branch lead to the same basic block, it doesn't
1901 matter which edge is taken. */
1902 if (true_edge
->dest
== false_edge
->dest
)
1905 /* Otherwise, try to determine which branch of the if() will be taken.
1906 If VAL is a constant but it can't be reduced to a 0 or a 1, then
1907 we don't really know which edge will be taken at runtime. This
1908 may happen when comparing addresses (e.g., if (&var1 == 4)). */
1909 if (integer_nonzerop (val
))
1911 else if (integer_zerop (val
))
1918 /* Given a constant value VAL and the entry block BB to a SWITCH_EXPR
1919 statement, determine which edge will be taken out of the block. Return
1920 NULL if any edge may be taken. */
1923 find_taken_edge_switch_expr (basic_block bb
, tree val
)
1925 tree switch_expr
, taken_case
;
1926 basic_block dest_bb
;
1929 if (TREE_CODE (val
) != INTEGER_CST
)
1932 switch_expr
= last_stmt (bb
);
1933 taken_case
= find_case_label_for_value (switch_expr
, val
);
1934 dest_bb
= label_to_block (CASE_LABEL (taken_case
));
1936 e
= find_edge (bb
, dest_bb
);
1943 /* Return the CASE_LABEL_EXPR that SWITCH_EXPR will take for VAL. */
1946 find_case_label_for_value (tree switch_expr
, tree val
)
1948 tree vec
= SWITCH_LABELS (switch_expr
);
1949 size_t i
, n
= TREE_VEC_LENGTH (vec
);
1950 tree default_case
= NULL
;
1952 for (i
= 0; i
< n
; ++i
)
1954 tree t
= TREE_VEC_ELT (vec
, i
);
1956 if (CASE_LOW (t
) == NULL
)
1958 else if (CASE_HIGH (t
) == NULL
)
1960 /* A `normal' case label. */
1961 if (tree_int_cst_equal (CASE_LOW (t
), val
))
1966 /* A case range. We can only handle integer ranges. */
1967 if (tree_int_cst_compare (CASE_LOW (t
), val
) <= 0
1968 && tree_int_cst_compare (CASE_HIGH (t
), val
) >= 0)
1976 return default_case
;
1980 /* If all the PHI nodes in DEST have alternatives for E1 and E2 and
1981 those alternatives are equal in each of the PHI nodes, then return
1982 true, else return false. */
1985 phi_alternatives_equal (basic_block dest
, edge e1
, edge e2
)
1987 tree phi
, val1
, val2
;
1990 for (phi
= phi_nodes (dest
); phi
; phi
= TREE_CHAIN (phi
))
1992 n1
= phi_arg_from_edge (phi
, e1
);
1993 n2
= phi_arg_from_edge (phi
, e2
);
1995 #ifdef ENABLE_CHECKING
1996 if (n1
< 0 || n2
< 0)
2000 val1
= PHI_ARG_DEF (phi
, n1
);
2001 val2
= PHI_ARG_DEF (phi
, n2
);
2003 if (!operand_equal_p (val1
, val2
, 0))
2011 /* Computing the Dominance Frontier:
2013 As described in Morgan, section 3.5, this may be done simply by
2014 walking the dominator tree bottom-up, computing the frontier for
2015 the children before the parent. When considering a block B,
2016 there are two cases:
2018 (1) A flow graph edge leaving B that does not lead to a child
2019 of B in the dominator tree must be a block that is either equal
2020 to B or not dominated by B. Such blocks belong in the frontier
2023 (2) Consider a block X in the frontier of one of the children C
2024 of B. If X is not equal to B and is not dominated by B, it
2025 is in the frontier of B. */
2028 compute_dominance_frontiers_1 (bitmap
*frontiers
, basic_block bb
, sbitmap done
)
2033 SET_BIT (done
, bb
->index
);
2035 /* Do the frontier of the children first. Not all children in the
2036 dominator tree (blocks dominated by this one) are children in the
2037 CFG, so check all blocks. */
2038 for (c
= first_dom_son (CDI_DOMINATORS
, bb
);
2040 c
= next_dom_son (CDI_DOMINATORS
, c
))
2042 if (! TEST_BIT (done
, c
->index
))
2043 compute_dominance_frontiers_1 (frontiers
, c
, done
);
2046 /* Find blocks conforming to rule (1) above. */
2047 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
2049 if (e
->dest
== EXIT_BLOCK_PTR
)
2051 if (get_immediate_dominator (CDI_DOMINATORS
, e
->dest
) != bb
)
2052 bitmap_set_bit (frontiers
[bb
->index
], e
->dest
->index
);
2055 /* Find blocks conforming to rule (2). */
2056 for (c
= first_dom_son (CDI_DOMINATORS
, bb
);
2058 c
= next_dom_son (CDI_DOMINATORS
, c
))
2062 EXECUTE_IF_SET_IN_BITMAP (frontiers
[c
->index
], 0, x
,
2064 if (get_immediate_dominator (CDI_DOMINATORS
, BASIC_BLOCK (x
)) != bb
)
2065 bitmap_set_bit (frontiers
[bb
->index
], x
);
2072 compute_dominance_frontiers (bitmap
*frontiers
)
2074 sbitmap done
= sbitmap_alloc (last_basic_block
);
2076 timevar_push (TV_DOM_FRONTIERS
);
2078 sbitmap_zero (done
);
2080 compute_dominance_frontiers_1 (frontiers
, ENTRY_BLOCK_PTR
->succ
->dest
, done
);
2082 sbitmap_free (done
);
2084 timevar_pop (TV_DOM_FRONTIERS
);
2089 /*---------------------------------------------------------------------------
2091 ---------------------------------------------------------------------------*/
2093 /* Dump tree-specific information of block BB to file OUTF. */
2096 tree_dump_bb (basic_block bb
, FILE *outf
, int indent
)
2098 dump_generic_bb (outf
, bb
, indent
, TDF_VOPS
);
2102 /* Dump a basic block on stderr. */
2105 debug_tree_bb (basic_block bb
)
2107 dump_bb (bb
, stderr
, 0);
2111 /* Dump basic block with index N on stderr. */
2114 debug_tree_bb_n (int n
)
2116 debug_tree_bb (BASIC_BLOCK (n
));
2117 return BASIC_BLOCK (n
);
2121 /* Dump the CFG on stderr.
2123 FLAGS are the same used by the tree dumping functions
2124 (see TDF_* in tree.h). */
2127 debug_tree_cfg (int flags
)
2129 dump_tree_cfg (stderr
, flags
);
2133 /* Dump the program showing basic block boundaries on the given FILE.
2135 FLAGS are the same used by the tree dumping functions (see TDF_* in
2139 dump_tree_cfg (FILE *file
, int flags
)
2141 if (flags
& TDF_DETAILS
)
2143 const char *funcname
2144 = lang_hooks
.decl_printable_name (current_function_decl
, 2);
2147 fprintf (file
, ";; Function %s\n\n", funcname
);
2148 fprintf (file
, ";; \n%d basic blocks, %d edges, last basic block %d.\n\n",
2149 n_basic_blocks
, n_edges
, last_basic_block
);
2151 brief_dump_cfg (file
);
2152 fprintf (file
, "\n");
2155 if (flags
& TDF_STATS
)
2156 dump_cfg_stats (file
);
2158 dump_function_to_file (current_function_decl
, file
, flags
| TDF_BLOCKS
);
2162 /* Dump CFG statistics on FILE. */
2165 dump_cfg_stats (FILE *file
)
2167 static long max_num_merged_labels
= 0;
2168 unsigned long size
, total
= 0;
2171 const char * const fmt_str
= "%-30s%-13s%12s\n";
2172 const char * const fmt_str_1
= "%-30s%13lu%11lu%c\n";
2173 const char * const fmt_str_3
= "%-43s%11lu%c\n";
2174 const char *funcname
2175 = lang_hooks
.decl_printable_name (current_function_decl
, 2);
2178 fprintf (file
, "\nCFG Statistics for %s\n\n", funcname
);
2180 fprintf (file
, "---------------------------------------------------------\n");
2181 fprintf (file
, fmt_str
, "", " Number of ", "Memory");
2182 fprintf (file
, fmt_str
, "", " instances ", "used ");
2183 fprintf (file
, "---------------------------------------------------------\n");
2185 size
= n_basic_blocks
* sizeof (struct basic_block_def
);
2187 fprintf (file
, fmt_str_1
, "Basic blocks", n_basic_blocks
, SCALE (size
),
2194 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
2197 size
= n_edges
* sizeof (struct edge_def
);
2199 fprintf (file
, fmt_str_1
, "Edges", n_edges
, SCALE (size
), LABEL (size
));
2201 size
= n_basic_blocks
* sizeof (struct bb_ann_d
);
2203 fprintf (file
, fmt_str_1
, "Basic block annotations", n_basic_blocks
,
2204 SCALE (size
), LABEL (size
));
2206 fprintf (file
, "---------------------------------------------------------\n");
2207 fprintf (file
, fmt_str_3
, "Total memory used by CFG data", SCALE (total
),
2209 fprintf (file
, "---------------------------------------------------------\n");
2210 fprintf (file
, "\n");
2212 if (cfg_stats
.num_merged_labels
> max_num_merged_labels
)
2213 max_num_merged_labels
= cfg_stats
.num_merged_labels
;
2215 fprintf (file
, "Coalesced label blocks: %ld (Max so far: %ld)\n",
2216 cfg_stats
.num_merged_labels
, max_num_merged_labels
);
2218 fprintf (file
, "\n");
2222 /* Dump CFG statistics on stderr. Keep extern so that it's always
2223 linked in the final executable. */
2226 debug_cfg_stats (void)
2228 dump_cfg_stats (stderr
);
2232 /* Dump the flowgraph to a .vcg FILE. */
2235 tree_cfg2vcg (FILE *file
)
2239 const char *funcname
2240 = lang_hooks
.decl_printable_name (current_function_decl
, 2);
2242 /* Write the file header. */
2243 fprintf (file
, "graph: { title: \"%s\"\n", funcname
);
2244 fprintf (file
, "node: { title: \"ENTRY\" label: \"ENTRY\" }\n");
2245 fprintf (file
, "node: { title: \"EXIT\" label: \"EXIT\" }\n");
2247 /* Write blocks and edges. */
2248 for (e
= ENTRY_BLOCK_PTR
->succ
; e
; e
= e
->succ_next
)
2250 fprintf (file
, "edge: { sourcename: \"ENTRY\" targetname: \"%d\"",
2253 if (e
->flags
& EDGE_FAKE
)
2254 fprintf (file
, " linestyle: dotted priority: 10");
2256 fprintf (file
, " linestyle: solid priority: 100");
2258 fprintf (file
, " }\n");
2264 enum tree_code head_code
, end_code
;
2265 const char *head_name
, *end_name
;
2268 tree first
= first_stmt (bb
);
2269 tree last
= last_stmt (bb
);
2273 head_code
= TREE_CODE (first
);
2274 head_name
= tree_code_name
[head_code
];
2275 head_line
= get_lineno (first
);
2278 head_name
= "no-statement";
2282 end_code
= TREE_CODE (last
);
2283 end_name
= tree_code_name
[end_code
];
2284 end_line
= get_lineno (last
);
2287 end_name
= "no-statement";
2289 fprintf (file
, "node: { title: \"%d\" label: \"#%d\\n%s (%d)\\n%s (%d)\"}\n",
2290 bb
->index
, bb
->index
, head_name
, head_line
, end_name
,
2293 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
2295 if (e
->dest
== EXIT_BLOCK_PTR
)
2296 fprintf (file
, "edge: { sourcename: \"%d\" targetname: \"EXIT\"", bb
->index
);
2298 fprintf (file
, "edge: { sourcename: \"%d\" targetname: \"%d\"", bb
->index
, e
->dest
->index
);
2300 if (e
->flags
& EDGE_FAKE
)
2301 fprintf (file
, " priority: 10 linestyle: dotted");
2303 fprintf (file
, " priority: 100 linestyle: solid");
2305 fprintf (file
, " }\n");
2308 if (bb
->next_bb
!= EXIT_BLOCK_PTR
)
2312 fputs ("}\n\n", file
);
2317 /*---------------------------------------------------------------------------
2318 Miscellaneous helpers
2319 ---------------------------------------------------------------------------*/
2321 /* Return true if T represents a stmt that always transfers control. */
2324 is_ctrl_stmt (tree t
)
2326 return (TREE_CODE (t
) == COND_EXPR
2327 || TREE_CODE (t
) == SWITCH_EXPR
2328 || TREE_CODE (t
) == GOTO_EXPR
2329 || TREE_CODE (t
) == RETURN_EXPR
2330 || TREE_CODE (t
) == RESX_EXPR
);
2334 /* Return true if T is a statement that may alter the flow of control
2335 (e.g., a call to a non-returning function). */
2338 is_ctrl_altering_stmt (tree t
)
2342 #if defined ENABLE_CHECKING
2347 switch (TREE_CODE (t
))
2350 /* A MODIFY_EXPR with a rhs of a call has the characteristics
2352 call
= TREE_OPERAND (t
, 1);
2353 if (TREE_CODE (call
) != CALL_EXPR
)
2358 /* A non-pure/const CALL_EXPR alters flow control if the current
2359 function has nonlocal labels. */
2360 if (TREE_SIDE_EFFECTS (t
)
2361 && current_function_has_nonlocal_label
)
2364 /* A CALL_EXPR also alters control flow if it does not return. */
2365 if (call_expr_flags (call
) & (ECF_NORETURN
| ECF_LONGJMP
))
2373 /* If a statement can throw, it alters control flow. */
2374 return tree_can_throw_internal (t
);
2378 /* Return true if T is a computed goto. */
2381 computed_goto_p (tree t
)
2383 return (TREE_CODE (t
) == GOTO_EXPR
2384 && TREE_CODE (GOTO_DESTINATION (t
)) != LABEL_DECL
);
2388 /* Checks whether EXPR is a simple local goto. */
2391 simple_goto_p (tree expr
)
2393 return (TREE_CODE (expr
) == GOTO_EXPR
2394 && TREE_CODE (GOTO_DESTINATION (expr
)) == LABEL_DECL
2395 && (decl_function_context (GOTO_DESTINATION (expr
))
2396 == current_function_decl
));
2400 /* Return true if T should start a new basic block. PREV_T is the
2401 statement preceding T. It is used when T is a label or a case label.
2402 Labels should only start a new basic block if their previous statement
2403 wasn't a label. Otherwise, sequence of labels would generate
2404 unnecessary basic blocks that only contain a single label. */
2407 stmt_starts_bb_p (tree t
, tree prev_t
)
2409 enum tree_code code
;
2414 /* LABEL_EXPRs start a new basic block only if the preceding
2415 statement wasn't a label of the same type. This prevents the
2416 creation of consecutive blocks that have nothing but a single
2418 code
= TREE_CODE (t
);
2419 if (code
== LABEL_EXPR
)
2421 /* Nonlocal and computed GOTO targets always start a new block. */
2422 if (code
== LABEL_EXPR
2423 && (DECL_NONLOCAL (LABEL_EXPR_LABEL (t
))
2424 || FORCED_LABEL (LABEL_EXPR_LABEL (t
))))
2427 if (prev_t
&& TREE_CODE (prev_t
) == code
)
2429 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (prev_t
)))
2432 cfg_stats
.num_merged_labels
++;
2443 /* Return true if T should end a basic block. */
2446 stmt_ends_bb_p (tree t
)
2448 return is_ctrl_stmt (t
) || is_ctrl_altering_stmt (t
);
2452 /* Add gotos that used to be represented implicitly in the CFG. */
2455 disband_implicit_edges (void)
2458 block_stmt_iterator last
;
2460 tree stmt
, label
, forward
;
2464 last
= bsi_last (bb
);
2465 stmt
= last_stmt (bb
);
2467 if (stmt
&& TREE_CODE (stmt
) == COND_EXPR
)
2469 /* Remove superfluous gotos from COND_EXPR branches. Moved
2470 from cfg_remove_useless_stmts here since it violates the
2471 invariants for tree--cfg correspondence and thus fits better
2472 here where we do it anyway. */
2473 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
2475 if (e
->dest
!= bb
->next_bb
)
2478 if (e
->flags
& EDGE_TRUE_VALUE
)
2479 COND_EXPR_THEN (stmt
) = build_empty_stmt ();
2480 else if (e
->flags
& EDGE_FALSE_VALUE
)
2481 COND_EXPR_ELSE (stmt
) = build_empty_stmt ();
2484 e
->flags
|= EDGE_FALLTHRU
;
2490 if (stmt
&& TREE_CODE (stmt
) == RETURN_EXPR
)
2492 /* Remove the RETURN_EXPR if we may fall though to the exit
2495 || bb
->succ
->succ_next
2496 || bb
->succ
->dest
!= EXIT_BLOCK_PTR
)
2499 if (bb
->next_bb
== EXIT_BLOCK_PTR
2500 && !TREE_OPERAND (stmt
, 0))
2503 bb
->succ
->flags
|= EDGE_FALLTHRU
;
2508 /* There can be no fallthru edge if the last statement is a control
2510 if (stmt
&& is_ctrl_stmt (stmt
))
2513 /* Find a fallthru edge and emit the goto if necessary. */
2514 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
2515 if (e
->flags
& EDGE_FALLTHRU
)
2519 || e
->dest
== bb
->next_bb
)
2522 if (e
->dest
== EXIT_BLOCK_PTR
)
2525 label
= tree_block_label (e
->dest
);
2527 /* If this is a goto to a goto, jump to the final destination.
2528 Handles unfactoring of the computed jumps.
2529 ??? Why bother putting this back together when rtl is just
2530 about to take it apart again? */
2531 forward
= last_and_only_stmt (e
->dest
);
2533 && TREE_CODE (forward
) == GOTO_EXPR
)
2534 label
= GOTO_DESTINATION (forward
);
2536 bsi_insert_after (&last
,
2537 build1 (GOTO_EXPR
, void_type_node
, label
),
2539 e
->flags
&= ~EDGE_FALLTHRU
;
2544 /* Remove all the blocks and edges that make up the flowgraph. */
2547 delete_tree_cfg (void)
2549 if (n_basic_blocks
> 0)
2550 free_blocks_annotations ();
2552 free_basic_block_vars ();
2553 basic_block_info
= NULL
;
2554 label_to_block_map
= NULL
;
2559 /* Return the first statement in basic block BB. */
2562 first_stmt (basic_block bb
)
2564 block_stmt_iterator i
= bsi_start (bb
);
2565 return !bsi_end_p (i
) ? bsi_stmt (i
) : NULL_TREE
;
2569 /* Return the last statement in basic block BB. */
2572 last_stmt (basic_block bb
)
2574 block_stmt_iterator b
= bsi_last (bb
);
2575 return !bsi_end_p (b
) ? bsi_stmt (b
) : NULL_TREE
;
2579 /* Return a pointer to the last statement in block BB. */
2582 last_stmt_ptr (basic_block bb
)
2584 block_stmt_iterator last
= bsi_last (bb
);
2585 return !bsi_end_p (last
) ? bsi_stmt_ptr (last
) : NULL
;
2589 /* Return the last statement of an otherwise empty block. Return NULL
2590 if the block is totally empty, or if it contains more than one
2594 last_and_only_stmt (basic_block bb
)
2596 block_stmt_iterator i
= bsi_last (bb
);
2602 last
= bsi_stmt (i
);
2607 /* Empty statements should no longer appear in the instruction stream.
2608 Everything that might have appeared before should be deleted by
2609 remove_useless_stmts, and the optimizers should just bsi_remove
2610 instead of smashing with build_empty_stmt.
2612 Thus the only thing that should appear here in a block containing
2613 one executable statement is a label. */
2614 prev
= bsi_stmt (i
);
2615 if (TREE_CODE (prev
) == LABEL_EXPR
)
2622 /* Mark BB as the basic block holding statement T. */
2625 set_bb_for_stmt (tree t
, basic_block bb
)
2627 if (TREE_CODE (t
) == STATEMENT_LIST
)
2629 tree_stmt_iterator i
;
2630 for (i
= tsi_start (t
); !tsi_end_p (i
); tsi_next (&i
))
2631 set_bb_for_stmt (tsi_stmt (i
), bb
);
2635 stmt_ann_t ann
= get_stmt_ann (t
);
2638 /* If the statement is a label, add the label to block-to-labels map
2639 so that we can speed up edge creation for GOTO_EXPRs. */
2640 if (TREE_CODE (t
) == LABEL_EXPR
)
2644 t
= LABEL_EXPR_LABEL (t
);
2645 uid
= LABEL_DECL_UID (t
);
2648 LABEL_DECL_UID (t
) = uid
= cfun
->last_label_uid
++;
2649 if (VARRAY_SIZE (label_to_block_map
) <= (unsigned) uid
)
2650 VARRAY_GROW (label_to_block_map
, 3 * uid
/ 2);
2654 #ifdef ENABLE_CHECKING
2655 /* We're moving an existing label. Make sure that we've
2656 removed it from the old block. */
2657 if (bb
&& VARRAY_BB (label_to_block_map
, uid
))
2661 VARRAY_BB (label_to_block_map
, uid
) = bb
;
2667 /* Insert statement (or statement list) T before the statement
2668 pointed-to by iterator I. M specifies how to update iterator I
2669 after insertion (see enum bsi_iterator_update). */
2672 bsi_insert_before (block_stmt_iterator
*i
, tree t
, enum bsi_iterator_update m
)
2674 set_bb_for_stmt (t
, i
->bb
);
2676 tsi_link_before (&i
->tsi
, t
, m
);
2680 /* Insert statement (or statement list) T after the statement
2681 pointed-to by iterator I. M specifies how to update iterator I
2682 after insertion (see enum bsi_iterator_update). */
2685 bsi_insert_after (block_stmt_iterator
*i
, tree t
, enum bsi_iterator_update m
)
2687 set_bb_for_stmt (t
, i
->bb
);
2689 tsi_link_after (&i
->tsi
, t
, m
);
2693 /* Remove the statement pointed to by iterator I. The iterator is updated
2694 to the next statement. */
2697 bsi_remove (block_stmt_iterator
*i
)
2699 tree t
= bsi_stmt (*i
);
2700 set_bb_for_stmt (t
, NULL
);
2702 tsi_delink (&i
->tsi
);
2706 /* Move the statement at FROM so it comes right after the statement at TO. */
2709 bsi_move_after (block_stmt_iterator
*from
, block_stmt_iterator
*to
)
2711 tree stmt
= bsi_stmt (*from
);
2713 bsi_insert_after (to
, stmt
, BSI_SAME_STMT
);
2717 /* Move the statement at FROM so it comes right before the statement at TO. */
2720 bsi_move_before (block_stmt_iterator
*from
, block_stmt_iterator
*to
)
2722 tree stmt
= bsi_stmt (*from
);
2724 bsi_insert_before (to
, stmt
, BSI_SAME_STMT
);
2728 /* Move the statement at FROM to the end of basic block BB. */
2731 bsi_move_to_bb_end (block_stmt_iterator
*from
, basic_block bb
)
2733 block_stmt_iterator last
= bsi_last (bb
);
2735 /* Have to check bsi_end_p because it could be an empty block. */
2736 if (!bsi_end_p (last
) && is_ctrl_stmt (bsi_stmt (last
)))
2737 bsi_move_before (from
, &last
);
2739 bsi_move_after (from
, &last
);
2743 /* Replace the contents of the statement pointed to by iterator BSI
2744 with STMT. If PRESERVE_EH_INFO is true, the exception handling
2745 information of the original statement is preserved. */
2748 bsi_replace (const block_stmt_iterator
*bsi
, tree stmt
, bool preserve_eh_info
)
2751 tree orig_stmt
= bsi_stmt (*bsi
);
2753 SET_EXPR_LOCUS (stmt
, EXPR_LOCUS (orig_stmt
));
2754 set_bb_for_stmt (stmt
, bsi
->bb
);
2756 /* Preserve EH region information from the original statement, if
2757 requested by the caller. */
2758 if (preserve_eh_info
)
2760 eh_region
= lookup_stmt_eh_region (orig_stmt
);
2762 add_stmt_to_eh_region (stmt
, eh_region
);
2765 *bsi_stmt_ptr (*bsi
) = stmt
;
2770 /* Insert the statement pointed-to by BSI into edge E. Every attempt
2771 is made to place the statement in an existing basic block, but
2772 sometimes that isn't possible. When it isn't possible, the edge is
2773 split and the statement is added to the new block.
2775 In all cases, the returned *BSI points to the correct location. The
2776 return value is true if insertion should be done after the location,
2777 or false if it should be done before the location. */
2780 tree_find_edge_insert_loc (edge e
, block_stmt_iterator
*bsi
)
2782 basic_block dest
, src
;
2788 /* If the destination has one predecessor which has no PHI nodes,
2789 insert there. Except for the exit block.
2791 The requirement for no PHI nodes could be relaxed. Basically we
2792 would have to examine the PHIs to prove that none of them used
2793 the value set by the statement we want to insert on E. That
2794 hardly seems worth the effort. */
2795 if (dest
->pred
->pred_next
== NULL
2796 && ! phi_nodes (dest
)
2797 && dest
!= EXIT_BLOCK_PTR
)
2799 *bsi
= bsi_start (dest
);
2800 if (bsi_end_p (*bsi
))
2803 /* Make sure we insert after any leading labels. */
2804 tmp
= bsi_stmt (*bsi
);
2805 while (TREE_CODE (tmp
) == LABEL_EXPR
)
2808 if (bsi_end_p (*bsi
))
2810 tmp
= bsi_stmt (*bsi
);
2813 if (bsi_end_p (*bsi
))
2815 *bsi
= bsi_last (dest
);
2822 /* If the source has one successor, the edge is not abnormal and
2823 the last statement does not end a basic block, insert there.
2824 Except for the entry block. */
2826 if ((e
->flags
& EDGE_ABNORMAL
) == 0
2827 && src
->succ
->succ_next
== NULL
2828 && src
!= ENTRY_BLOCK_PTR
)
2830 *bsi
= bsi_last (src
);
2831 if (bsi_end_p (*bsi
))
2834 tmp
= bsi_stmt (*bsi
);
2835 if (!stmt_ends_bb_p (tmp
))
2839 /* Otherwise, create a new basic block, and split this edge. */
2840 dest
= split_edge (e
);
2846 /* This routine will commit all pending edge insertions, creating any new
2847 basic blocks which are necessary.
2849 If specified, NEW_BLOCKS returns a count of the number of new basic
2850 blocks which were created. */
2853 bsi_commit_edge_inserts (int *new_blocks
)
2859 blocks
= n_basic_blocks
;
2861 bsi_commit_edge_inserts_1 (ENTRY_BLOCK_PTR
->succ
);
2864 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
2865 bsi_commit_edge_inserts_1 (e
);
2868 *new_blocks
= n_basic_blocks
- blocks
;
2872 /* Commit insertions pending at edge E. */
2875 bsi_commit_edge_inserts_1 (edge e
)
2877 if (PENDING_STMT (e
))
2879 block_stmt_iterator bsi
;
2880 tree stmt
= PENDING_STMT (e
);
2882 PENDING_STMT (e
) = NULL_TREE
;
2884 if (tree_find_edge_insert_loc (e
, &bsi
))
2885 bsi_insert_after (&bsi
, stmt
, BSI_NEW_STMT
);
2887 bsi_insert_before (&bsi
, stmt
, BSI_NEW_STMT
);
2892 /* Add STMT to the pending list of edge E. No actual insertion is
2893 made until a call to bsi_commit_edge_inserts () is made. */
2896 bsi_insert_on_edge (edge e
, tree stmt
)
2898 append_to_statement_list (stmt
, &PENDING_STMT (e
));
2902 /* Specialized edge insertion for SSA-PRE. FIXME: This should
2903 probably disappear. The only reason it's here is because PRE needs
2904 the call to tree_find_edge_insert_loc(). */
2906 void pre_insert_on_edge (edge e
, tree stmt
);
2909 pre_insert_on_edge (edge e
, tree stmt
)
2911 block_stmt_iterator bsi
;
2913 if (PENDING_STMT (e
))
2916 if (tree_find_edge_insert_loc (e
, &bsi
))
2917 bsi_insert_after (&bsi
, stmt
, BSI_NEW_STMT
);
2919 bsi_insert_before (&bsi
, stmt
, BSI_NEW_STMT
);
2923 /*---------------------------------------------------------------------------
2924 Tree specific functions for CFG manipulation
2925 ---------------------------------------------------------------------------*/
2927 /* Split a (typically critical) edge EDGE_IN. Return the new block.
2928 Abort on abnormal edges. */
2931 tree_split_edge (edge edge_in
)
2933 basic_block new_bb
, after_bb
, dest
, src
;
2938 /* Abnormal edges cannot be split. */
2939 if (edge_in
->flags
& EDGE_ABNORMAL
)
2943 dest
= edge_in
->dest
;
2945 /* Place the new block in the block list. Try to keep the new block
2946 near its "logical" location. This is of most help to humans looking
2947 at debugging dumps. */
2948 for (e
= dest
->pred
; e
; e
= e
->pred_next
)
2949 if (e
->src
->next_bb
== dest
)
2952 after_bb
= dest
->prev_bb
;
2954 after_bb
= edge_in
->src
;
2956 new_bb
= create_empty_bb (after_bb
);
2957 new_edge
= make_edge (new_bb
, dest
, EDGE_FALLTHRU
);
2959 /* Find all the PHI arguments on the original edge, and change them to
2960 the new edge. Do it before redirection, so that the argument does not
2962 for (phi
= phi_nodes (dest
); phi
; phi
= TREE_CHAIN (phi
))
2964 num_elem
= PHI_NUM_ARGS (phi
);
2965 for (i
= 0; i
< num_elem
; i
++)
2966 if (PHI_ARG_EDGE (phi
, i
) == edge_in
)
2968 PHI_ARG_EDGE (phi
, i
) = new_edge
;
2973 if (!redirect_edge_and_branch (edge_in
, new_bb
))
2976 if (PENDING_STMT (edge_in
))
2983 /* Return true when BB has label LABEL in it. */
2986 has_label_p (basic_block bb
, tree label
)
2988 block_stmt_iterator bsi
;
2990 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
2992 tree stmt
= bsi_stmt (bsi
);
2994 if (TREE_CODE (stmt
) != LABEL_EXPR
)
2996 if (LABEL_EXPR_LABEL (stmt
) == label
)
3003 /* Callback for walk_tree, check that all elements with address taken are
3004 properly noticed as such. */
3007 verify_expr (tree
*tp
, int *walk_subtrees ATTRIBUTE_UNUSED
,
3008 void *data ATTRIBUTE_UNUSED
)
3015 switch (TREE_CODE (t
))
3018 if (SSA_NAME_IN_FREE_LIST (t
))
3020 error ("SSA name in freelist but still referenced");
3026 x
= TREE_OPERAND (t
, 0);
3027 if (TREE_CODE (x
) == BIT_FIELD_REF
3028 && is_gimple_reg (TREE_OPERAND (x
, 0)))
3030 error ("GIMPLE register modified with BIT_FIELD_REF");
3036 x
= TREE_OPERAND (t
, 0);
3037 while (TREE_CODE (x
) == ARRAY_REF
3038 || TREE_CODE (x
) == COMPONENT_REF
3039 || TREE_CODE (x
) == REALPART_EXPR
3040 || TREE_CODE (x
) == IMAGPART_EXPR
)
3041 x
= TREE_OPERAND (x
, 0);
3042 if (TREE_CODE (x
) != VAR_DECL
&& TREE_CODE (x
) != PARM_DECL
)
3044 if (!TREE_ADDRESSABLE (x
))
3046 error ("address taken, but ADDRESSABLE bit not set");
3052 x
= TREE_OPERAND (t
, 0);
3053 if (TREE_CODE (TREE_TYPE (x
)) != BOOLEAN_TYPE
)
3055 error ("non-boolean used in condition");
3062 case FIX_TRUNC_EXPR
:
3064 case FIX_FLOOR_EXPR
:
3065 case FIX_ROUND_EXPR
:
3070 case NON_LVALUE_EXPR
:
3071 case TRUTH_NOT_EXPR
:
3072 x
= TREE_OPERAND (t
, 0);
3073 /* We check for constants explicitly since they are not considered
3074 gimple invariants if they overflowed. */
3075 if (TREE_CODE_CLASS (TREE_CODE (x
)) != 'c'
3076 && !is_gimple_val (x
))
3078 error ("Invalid operand to unary operator");
3093 case UNORDERED_EXPR
:
3103 case TRUNC_DIV_EXPR
:
3105 case FLOOR_DIV_EXPR
:
3106 case ROUND_DIV_EXPR
:
3107 case TRUNC_MOD_EXPR
:
3109 case FLOOR_MOD_EXPR
:
3110 case ROUND_MOD_EXPR
:
3112 case EXACT_DIV_EXPR
:
3122 x
= TREE_OPERAND (t
, 0);
3123 /* We check for constants explicitly since they are not considered
3124 gimple invariants if they overflowed. */
3125 if (TREE_CODE_CLASS (TREE_CODE (x
)) != 'c'
3126 && !is_gimple_val (x
))
3128 error ("Invalid operand to binary operator");
3131 x
= TREE_OPERAND (t
, 1);
3132 /* We check for constants explicitly since they are not considered
3133 gimple invariants if they overflowed. */
3134 if (TREE_CODE_CLASS (TREE_CODE (x
)) != 'c'
3135 && !is_gimple_val (x
))
3137 error ("Invalid operand to binary operator");
3149 /* Verify STMT, return true if STMT is not in GIMPLE form.
3150 TODO: Implement type checking. */
3153 verify_stmt (tree stmt
)
3157 if (!is_gimple_stmt (stmt
))
3159 error ("Is not a valid GIMPLE statement.");
3160 debug_generic_stmt (stmt
);
3164 addr
= walk_tree (&stmt
, verify_expr
, NULL
, NULL
);
3167 debug_generic_stmt (addr
);
3175 /* Return true when the T can be shared. */
3178 tree_node_can_be_shared (tree t
)
3180 if (TYPE_P (t
) || DECL_P (t
)
3181 /* We check for constants explicitly since they are not considered
3182 gimple invariants if they overflowed. */
3183 || TREE_CODE_CLASS (TREE_CODE (t
)) == 'c'
3184 || is_gimple_min_invariant (t
)
3185 || TREE_CODE (t
) == SSA_NAME
)
3188 while ((TREE_CODE (t
) == ARRAY_REF
3189 /* We check for constants explicitly since they are not considered
3190 gimple invariants if they overflowed. */
3191 && (TREE_CODE_CLASS (TREE_CODE (TREE_OPERAND (t
, 1))) == 'c'
3192 || is_gimple_min_invariant (TREE_OPERAND (t
, 1))))
3193 || (TREE_CODE (t
) == COMPONENT_REF
3194 || TREE_CODE (t
) == REALPART_EXPR
3195 || TREE_CODE (t
) == IMAGPART_EXPR
))
3196 t
= TREE_OPERAND (t
, 0);
3205 /* Called via walk_trees. Verify tree sharing. */
3208 verify_node_sharing (tree
* tp
, int *walk_subtrees
, void *data
)
3210 htab_t htab
= (htab_t
) data
;
3213 if (tree_node_can_be_shared (*tp
))
3215 *walk_subtrees
= false;
3219 slot
= htab_find_slot (htab
, *tp
, INSERT
);
3228 /* Verify the GIMPLE statement chain. */
3234 block_stmt_iterator bsi
;
3239 timevar_push (TV_TREE_STMT_VERIFY
);
3240 htab
= htab_create (37, htab_hash_pointer
, htab_eq_pointer
, NULL
);
3247 for (phi
= phi_nodes (bb
); phi
; phi
= TREE_CHAIN (phi
))
3249 int phi_num_args
= PHI_NUM_ARGS (phi
);
3251 for (i
= 0; i
< phi_num_args
; i
++)
3253 tree t
= PHI_ARG_DEF (phi
, i
);
3256 /* Addressable variables do have SSA_NAMEs but they
3257 are not considered gimple values. */
3258 if (TREE_CODE (t
) != SSA_NAME
3259 && TREE_CODE (t
) != FUNCTION_DECL
3260 && !is_gimple_val (t
))
3262 error ("PHI def is not a GIMPLE value");
3263 debug_generic_stmt (phi
);
3264 debug_generic_stmt (t
);
3268 addr
= walk_tree (&t
, verify_expr
, NULL
, NULL
);
3271 debug_generic_stmt (addr
);
3275 addr
= walk_tree (&t
, verify_node_sharing
, htab
, NULL
);
3278 error ("Incorrect sharing of tree nodes");
3279 debug_generic_stmt (phi
);
3280 debug_generic_stmt (addr
);
3286 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
3288 tree stmt
= bsi_stmt (bsi
);
3289 err
|= verify_stmt (stmt
);
3290 addr
= walk_tree (&stmt
, verify_node_sharing
, htab
, NULL
);
3293 error ("Incorrect sharing of tree nodes");
3294 debug_generic_stmt (stmt
);
3295 debug_generic_stmt (addr
);
3302 internal_error ("verify_stmts failed.");
3305 timevar_pop (TV_TREE_STMT_VERIFY
);
3309 /* Verifies that the flow information is OK. */
3312 tree_verify_flow_info (void)
3316 block_stmt_iterator bsi
;
3320 if (ENTRY_BLOCK_PTR
->stmt_list
)
3322 error ("ENTRY_BLOCK has a statement list associated with it\n");
3326 if (EXIT_BLOCK_PTR
->stmt_list
)
3328 error ("EXIT_BLOCK has a statement list associated with it\n");
3332 for (e
= EXIT_BLOCK_PTR
->pred
; e
; e
= e
->pred_next
)
3333 if (e
->flags
& EDGE_FALLTHRU
)
3335 error ("Fallthru to exit from bb %d\n", e
->src
->index
);
3341 bool found_ctrl_stmt
= false;
3343 /* Skip labels on the start of basic block. */
3344 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
3346 if (TREE_CODE (bsi_stmt (bsi
)) != LABEL_EXPR
)
3349 if (label_to_block (LABEL_EXPR_LABEL (bsi_stmt (bsi
))) != bb
)
3351 error ("Label %s to block does not match in bb %d\n",
3352 IDENTIFIER_POINTER (DECL_NAME (bsi_stmt (bsi
))),
3357 if (decl_function_context (LABEL_EXPR_LABEL (bsi_stmt (bsi
)))
3358 != current_function_decl
)
3360 error ("Label %s has incorrect context in bb %d\n",
3361 IDENTIFIER_POINTER (DECL_NAME (bsi_stmt (bsi
))),
3367 /* Verify that body of basic block BB is free of control flow. */
3368 for (; !bsi_end_p (bsi
); bsi_next (&bsi
))
3370 tree stmt
= bsi_stmt (bsi
);
3372 if (found_ctrl_stmt
)
3374 error ("Control flow in the middle of basic block %d\n",
3379 if (stmt_ends_bb_p (stmt
))
3380 found_ctrl_stmt
= true;
3382 if (TREE_CODE (stmt
) == LABEL_EXPR
)
3384 error ("Label %s in the middle of basic block %d\n",
3385 IDENTIFIER_POINTER (DECL_NAME (stmt
)),
3390 bsi
= bsi_last (bb
);
3391 if (bsi_end_p (bsi
))
3394 stmt
= bsi_stmt (bsi
);
3396 if (is_ctrl_stmt (stmt
))
3398 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
3399 if (e
->flags
& EDGE_FALLTHRU
)
3401 error ("Fallthru edge after a control statement in bb %d \n",
3407 switch (TREE_CODE (stmt
))
3413 if (TREE_CODE (COND_EXPR_THEN (stmt
)) != GOTO_EXPR
3414 || TREE_CODE (COND_EXPR_ELSE (stmt
)) != GOTO_EXPR
)
3416 error ("Structured COND_EXPR at the end of bb %d\n", bb
->index
);
3420 extract_true_false_edges_from_block (bb
, &true_edge
, &false_edge
);
3422 if (!true_edge
|| !false_edge
3423 || !(true_edge
->flags
& EDGE_TRUE_VALUE
)
3424 || !(false_edge
->flags
& EDGE_FALSE_VALUE
)
3425 || (true_edge
->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
))
3426 || (false_edge
->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
))
3427 || bb
->succ
->succ_next
->succ_next
)
3429 error ("Wrong outgoing edge flags at end of bb %d\n",
3434 if (!has_label_p (true_edge
->dest
,
3435 GOTO_DESTINATION (COND_EXPR_THEN (stmt
))))
3437 error ("`then' label does not match edge at end of bb %d\n",
3442 if (!has_label_p (false_edge
->dest
,
3443 GOTO_DESTINATION (COND_EXPR_ELSE (stmt
))))
3445 error ("`else' label does not match edge at end of bb %d\n",
3453 if (simple_goto_p (stmt
))
3455 error ("Explicit goto at end of bb %d\n", bb
->index
);
3460 /* FIXME. We should double check that the labels in the
3461 destination blocks have their address taken. */
3462 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
3463 if ((e
->flags
& (EDGE_FALLTHRU
| EDGE_TRUE_VALUE
3464 | EDGE_FALSE_VALUE
))
3465 || !(e
->flags
& EDGE_ABNORMAL
))
3467 error ("Wrong outgoing edge flags at end of bb %d\n",
3475 if (!bb
->succ
|| bb
->succ
->succ_next
3476 || (bb
->succ
->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
3477 | EDGE_TRUE_VALUE
| EDGE_FALSE_VALUE
)))
3479 error ("Wrong outgoing edge flags at end of bb %d\n", bb
->index
);
3482 if (bb
->succ
->dest
!= EXIT_BLOCK_PTR
)
3484 error ("Return edge does not point to exit in bb %d\n",
3496 vec
= SWITCH_LABELS (stmt
);
3497 n
= TREE_VEC_LENGTH (vec
);
3499 /* Mark all the destination basic blocks. */
3500 for (i
= 0; i
< n
; ++i
)
3502 tree lab
= CASE_LABEL (TREE_VEC_ELT (vec
, i
));
3503 basic_block label_bb
= label_to_block (lab
);
3505 if (label_bb
->aux
&& label_bb
->aux
!= (void *)1)
3507 label_bb
->aux
= (void *)1;
3510 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
3514 error ("Extra outgoing edge %d->%d\n",
3515 bb
->index
, e
->dest
->index
);
3518 e
->dest
->aux
= (void *)2;
3519 if ((e
->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
3520 | EDGE_TRUE_VALUE
| EDGE_FALSE_VALUE
)))
3522 error ("Wrong outgoing edge flags at end of bb %d\n",
3528 /* Check that we have all of them. */
3529 for (i
= 0; i
< n
; ++i
)
3531 tree lab
= CASE_LABEL (TREE_VEC_ELT (vec
, i
));
3532 basic_block label_bb
= label_to_block (lab
);
3534 if (label_bb
->aux
!= (void *)2)
3536 error ("Missing edge %i->%i\n",
3537 bb
->index
, label_bb
->index
);
3542 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
3543 e
->dest
->aux
= (void *)0;
3550 if (dom_computed
[CDI_DOMINATORS
] >= DOM_NO_FAST_QUERY
)
3551 verify_dominators (CDI_DOMINATORS
);
3557 /* Updates phi nodes after creating forwarder block joined
3558 by edge FALLTHRU. */
3561 tree_make_forwarder_block (edge fallthru
)
3564 basic_block dummy
, bb
;
3565 tree phi
, new_phi
, var
;
3567 dummy
= fallthru
->src
;
3568 bb
= fallthru
->dest
;
3570 if (!bb
->pred
->pred_next
)
3573 /* If we redirected a branch we must create new phi nodes at the
3575 for (phi
= phi_nodes (dummy
); phi
; phi
= TREE_CHAIN (phi
))
3577 var
= PHI_RESULT (phi
);
3578 new_phi
= create_phi_node (var
, bb
);
3579 SSA_NAME_DEF_STMT (var
) = new_phi
;
3580 PHI_RESULT (phi
) = make_ssa_name (SSA_NAME_VAR (var
), phi
);
3581 add_phi_arg (&new_phi
, PHI_RESULT (phi
), fallthru
);
3584 /* Ensure that the PHI node chains are in the same order. */
3585 set_phi_nodes (bb
, nreverse (phi_nodes (bb
)));
3587 /* Add the arguments we have stored on edges. */
3588 for (e
= bb
->pred
; e
; e
= e
->pred_next
)
3593 for (phi
= phi_nodes (bb
), var
= PENDING_STMT (e
);
3595 phi
= TREE_CHAIN (phi
), var
= TREE_CHAIN (var
))
3596 add_phi_arg (&phi
, TREE_VALUE (var
), e
);
3598 PENDING_STMT (e
) = NULL
;
3603 /* Return true if basic block BB does nothing except pass control
3604 flow to another block and that we can safely insert a label at
3605 the start of the successor block. */
3608 tree_forwarder_block_p (basic_block bb
)
3610 block_stmt_iterator bsi
;
3613 /* If we have already determined that this block is not forwardable,
3614 then no further checks are necessary. */
3615 if (! bb_ann (bb
)->forwardable
)
3618 /* BB must have a single outgoing normal edge. Otherwise it can not be
3619 a forwarder block. */
3621 || bb
->succ
->succ_next
3622 || bb
->succ
->dest
== EXIT_BLOCK_PTR
3623 || (bb
->succ
->flags
& EDGE_ABNORMAL
)
3624 || bb
== ENTRY_BLOCK_PTR
)
3626 bb_ann (bb
)->forwardable
= 0;
3630 /* Successors of the entry block are not forwarders. */
3631 for (e
= ENTRY_BLOCK_PTR
->succ
; e
; e
= e
->succ_next
)
3634 bb_ann (bb
)->forwardable
= 0;
3638 /* BB can not have any PHI nodes. This could potentially be relaxed
3639 early in compilation if we re-rewrote the variables appearing in
3640 any PHI nodes in forwarder blocks. */
3643 bb_ann (bb
)->forwardable
= 0;
3647 /* Now walk through the statements. We can ignore labels, anything else
3648 means this is not a forwarder block. */
3649 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
3651 tree stmt
= bsi_stmt (bsi
);
3653 switch (TREE_CODE (stmt
))
3656 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt
)))
3661 bb_ann (bb
)->forwardable
= 0;
3670 /* Thread jumps over empty statements.
3672 This code should _not_ thread over obviously equivalent conditions
3673 as that requires nontrivial updates to the SSA graph. */
3678 edge e
, next
, last
, old
;
3679 basic_block bb
, dest
, tmp
;
3682 bool retval
= false;
3685 bb_ann (bb
)->forwardable
= 1;
3687 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
, EXIT_BLOCK_PTR
, next_bb
)
3689 /* Don't waste time on unreachable blocks. */
3693 /* Nor on forwarders. */
3694 if (tree_forwarder_block_p (bb
))
3697 /* This block is now part of a forwarding path, mark it as not
3698 forwardable so that we can detect loops. This bit will be
3700 bb_ann (bb
)->forwardable
= 0;
3702 /* Examine each of our block's successors to see if it is
3704 for (e
= bb
->succ
; e
; e
= next
)
3706 next
= e
->succ_next
;
3708 /* If the edge is abnormal or its destination is not
3709 forwardable, then there's nothing to do. */
3710 if ((e
->flags
& EDGE_ABNORMAL
)
3711 || !tree_forwarder_block_p (e
->dest
))
3714 /* Now walk through as many forwarder block as possible to
3715 find the ultimate destination we want to thread our jump
3717 last
= e
->dest
->succ
;
3718 bb_ann (e
->dest
)->forwardable
= 0;
3719 for (dest
= e
->dest
->succ
->dest
;
3720 tree_forwarder_block_p (dest
);
3722 dest
= dest
->succ
->dest
)
3724 /* An infinite loop detected. We redirect the edge anyway, so
3725 that the loop is shrinked into single basic block. */
3726 if (!bb_ann (dest
)->forwardable
)
3729 if (dest
->succ
->dest
== EXIT_BLOCK_PTR
)
3732 bb_ann (dest
)->forwardable
= 0;
3735 /* Reset the forwardable marks to 1. */
3738 tmp
= tmp
->succ
->dest
)
3739 bb_ann (tmp
)->forwardable
= 1;
3741 if (dest
== e
->dest
)
3744 old
= find_edge (bb
, dest
);
3747 /* If there already is an edge, check whether the values
3748 in phi nodes differ. */
3749 if (!phi_alternatives_equal (dest
, last
, old
))
3751 /* The previous block is forwarder. Redirect our jump
3752 to that target instead since we know it has no PHI
3753 nodes that will need updating. */
3756 /* That might mean that no forwarding at all is possible. */
3757 if (dest
== e
->dest
)
3760 old
= find_edge (bb
, dest
);
3764 /* Perform the redirection. */
3766 e
= redirect_edge_and_branch (e
, dest
);
3768 /* TODO -- updating dominators in this case is simple. */
3769 free_dominance_info (CDI_DOMINATORS
);
3773 /* Update PHI nodes. We know that the new argument should
3774 have the same value as the argument associated with LAST.
3775 Otherwise we would have changed our target block above. */
3776 for (phi
= phi_nodes (dest
); phi
; phi
= TREE_CHAIN (phi
))
3778 arg
= phi_arg_from_edge (phi
, last
);
3781 add_phi_arg (&phi
, PHI_ARG_DEF (phi
, arg
), e
);
3786 /* Reset the forwardable bit on our block since it's no longer in
3787 a forwarding chain path. */
3788 bb_ann (bb
)->forwardable
= 1;
3795 /* Return a non-special label in the head of basic block BLOCK.
3796 Create one if it doesn't exist. */
3799 tree_block_label (basic_block bb
)
3801 block_stmt_iterator i
, s
= bsi_start (bb
);
3805 for (i
= s
; !bsi_end_p (i
); first
= false, bsi_next (&i
))
3807 stmt
= bsi_stmt (i
);
3808 if (TREE_CODE (stmt
) != LABEL_EXPR
)
3810 label
= LABEL_EXPR_LABEL (stmt
);
3811 if (!DECL_NONLOCAL (label
))
3814 bsi_move_before (&i
, &s
);
3819 label
= create_artificial_label ();
3820 stmt
= build1 (LABEL_EXPR
, void_type_node
, label
);
3821 bsi_insert_before (&s
, stmt
, BSI_NEW_STMT
);
3826 /* Attempt to perform edge redirection by replacing a possibly complex
3827 jump instruction by a goto or by removing the jump completely.
3828 This can apply only if all edges now point to the same block. The
3829 parameters and return values are equivalent to
3830 redirect_edge_and_branch. */
3833 tree_try_redirect_by_replacing_jump (edge e
, basic_block target
)
3835 basic_block src
= e
->src
;
3837 block_stmt_iterator b
;
3840 /* Verify that all targets will be TARGET. */
3841 for (tmp
= src
->succ
; tmp
; tmp
= tmp
->succ_next
)
3842 if (tmp
->dest
!= target
&& tmp
!= e
)
3851 stmt
= bsi_stmt (b
);
3853 if (TREE_CODE (stmt
) == COND_EXPR
3854 || TREE_CODE (stmt
) == SWITCH_EXPR
)
3857 e
= ssa_redirect_edge (e
, target
);
3858 e
->flags
= EDGE_FALLTHRU
;
3866 /* Redirect E to DEST. Return NULL on failure. Otherwise, return the
3867 edge representing the redirected branch. */
3870 tree_redirect_edge_and_branch (edge e
, basic_block dest
)
3872 basic_block bb
= e
->src
;
3873 block_stmt_iterator bsi
;
3877 if (e
->flags
& (EDGE_ABNORMAL_CALL
| EDGE_EH
))
3880 if (e
->src
!= ENTRY_BLOCK_PTR
3881 && (ret
= tree_try_redirect_by_replacing_jump (e
, dest
)))
3884 if (e
->dest
== dest
)
3887 label
= tree_block_label (dest
);
3889 bsi
= bsi_last (bb
);
3890 stmt
= bsi_end_p (bsi
) ? NULL
: bsi_stmt (bsi
);
3892 switch (stmt
? TREE_CODE (stmt
) : ERROR_MARK
)
3895 stmt
= (e
->flags
& EDGE_TRUE_VALUE
3896 ? COND_EXPR_THEN (stmt
)
3897 : COND_EXPR_ELSE (stmt
));
3898 GOTO_DESTINATION (stmt
) = label
;
3902 /* No non-abnormal edges should lead from a non-simple goto, and
3903 simple ones should be represented implicitly. */
3908 tree vec
= SWITCH_LABELS (stmt
);
3909 size_t i
, n
= TREE_VEC_LENGTH (vec
);
3911 for (i
= 0; i
< n
; ++i
)
3913 tree elt
= TREE_VEC_ELT (vec
, i
);
3914 if (label_to_block (CASE_LABEL (elt
)) == e
->dest
)
3915 CASE_LABEL (elt
) = label
;
3922 e
->flags
|= EDGE_FALLTHRU
;
3926 /* Otherwise it must be a fallthru edge, and we don't need to
3927 do anything besides redirecting it. */
3928 if (!(e
->flags
& EDGE_FALLTHRU
))
3933 /* Update/insert PHI nodes as necessary. */
3935 /* Now update the edges in the CFG. */
3936 e
= ssa_redirect_edge (e
, dest
);
3942 /* Simple wrapper, as we can always redirect fallthru edges. */
3945 tree_redirect_edge_and_branch_force (edge e
, basic_block dest
)
3947 e
= tree_redirect_edge_and_branch (e
, dest
);
3955 /* Splits basic block BB after statement STMT (but at least after the
3956 labels). If STMT is NULL, BB is split just after the labels. */
3959 tree_split_block (basic_block bb
, void *stmt
)
3961 block_stmt_iterator bsi
, bsi_tgt
;
3966 new_bb
= create_empty_bb (bb
);
3968 /* Redirect the outgoing edges. */
3969 new_bb
->succ
= bb
->succ
;
3971 for (e
= new_bb
->succ
; e
; e
= e
->succ_next
)
3974 if (stmt
&& TREE_CODE ((tree
) stmt
) == LABEL_EXPR
)
3977 /* Move everything from BSI to the new basic block. */
3978 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
3980 act
= bsi_stmt (bsi
);
3981 if (TREE_CODE (act
) == LABEL_EXPR
)
3994 bsi_tgt
= bsi_start (new_bb
);
3995 while (!bsi_end_p (bsi
))
3997 act
= bsi_stmt (bsi
);
3999 bsi_insert_after (&bsi_tgt
, act
, BSI_NEW_STMT
);
4006 /* Moves basic block BB after block AFTER. */
4009 tree_move_block_after (basic_block bb
, basic_block after
)
4011 if (bb
->prev_bb
== after
)
4015 link_block (bb
, after
);
4021 /* Return true if basic_block can be duplicated. */
4024 tree_can_duplicate_bb_p (basic_block bb ATTRIBUTE_UNUSED
)
4030 /* Create a duplicate of the basic block BB. NOTE: This does not
4031 preserve SSA form. */
4034 tree_duplicate_bb (basic_block bb
)
4037 block_stmt_iterator bsi
, bsi_tgt
;
4039 new_bb
= create_empty_bb (EXIT_BLOCK_PTR
->prev_bb
);
4040 bsi_tgt
= bsi_start (new_bb
);
4041 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
4043 tree stmt
= bsi_stmt (bsi
);
4045 if (TREE_CODE (stmt
) == LABEL_EXPR
)
4048 bsi_insert_after (&bsi_tgt
, unshare_expr (stmt
), BSI_NEW_STMT
);
4055 /* Dump FUNCTION_DECL FN to file FILE using FLAGS (see TDF_* in tree.h) */
4058 dump_function_to_file (tree fn
, FILE *file
, int flags
)
4060 tree arg
, vars
, var
;
4061 bool ignore_topmost_bind
= false, any_var
= false;
4065 fprintf (file
, "%s (", lang_hooks
.decl_printable_name (fn
, 2));
4067 arg
= DECL_ARGUMENTS (fn
);
4070 print_generic_expr (file
, arg
, dump_flags
);
4071 if (TREE_CHAIN (arg
))
4072 fprintf (file
, ", ");
4073 arg
= TREE_CHAIN (arg
);
4075 fprintf (file
, ")\n");
4077 if (flags
& TDF_RAW
)
4079 dump_node (fn
, TDF_SLIM
| flags
, file
);
4083 /* When GIMPLE is lowered, the variables are no longer available in
4084 BIND_EXPRs, so display them separately. */
4085 if (cfun
&& cfun
->unexpanded_var_list
)
4087 ignore_topmost_bind
= true;
4089 fprintf (file
, "{\n");
4090 for (vars
= cfun
->unexpanded_var_list
; vars
; vars
= TREE_CHAIN (vars
))
4092 var
= TREE_VALUE (vars
);
4094 print_generic_decl (file
, var
, flags
);
4095 fprintf (file
, "\n");
4101 if (basic_block_info
)
4103 /* Make a CFG based dump. */
4104 if (!ignore_topmost_bind
)
4105 fprintf (file
, "{\n");
4107 if (any_var
&& n_basic_blocks
)
4108 fprintf (file
, "\n");
4111 dump_generic_bb (file
, bb
, 2, flags
);
4113 fprintf (file
, "}\n");
4119 /* Make a tree based dump. */
4120 chain
= DECL_SAVED_TREE (fn
);
4122 if (TREE_CODE (chain
) == BIND_EXPR
)
4124 if (ignore_topmost_bind
)
4126 chain
= BIND_EXPR_BODY (chain
);
4134 if (!ignore_topmost_bind
)
4135 fprintf (file
, "{\n");
4140 fprintf (file
, "\n");
4142 print_generic_stmt_indented (file
, chain
, flags
, indent
);
4143 if (ignore_topmost_bind
)
4144 fprintf (file
, "}\n");
4147 fprintf (file
, "\n\n");
4151 /* Pretty print of the loops intermediate representation. */
4152 static void print_loop (FILE *, struct loop
*, int);
4153 static void print_pred_bbs (FILE *, edge
);
4154 static void print_succ_bbs (FILE *, edge
);
4157 /* Print the predecessors indexes of edge E on FILE. */
4160 print_pred_bbs (FILE *file
, edge e
)
4165 else if (e
->pred_next
== NULL
)
4166 fprintf (file
, "bb_%d", e
->src
->index
);
4170 fprintf (file
, "bb_%d, ", e
->src
->index
);
4171 print_pred_bbs (file
, e
->pred_next
);
4176 /* Print the successors indexes of edge E on FILE. */
4179 print_succ_bbs (FILE *file
, edge e
)
4183 else if (e
->succ_next
== NULL
)
4184 fprintf (file
, "bb_%d", e
->dest
->index
);
4187 fprintf (file
, "bb_%d, ", e
->dest
->index
);
4188 print_succ_bbs (file
, e
->succ_next
);
4193 /* Pretty print LOOP on FILE, indented INDENT spaces. */
4196 print_loop (FILE *file
, struct loop
*loop
, int indent
)
4204 s_indent
= (char *) alloca ((size_t) indent
+ 1);
4205 memset ((void *) s_indent
, ' ', (size_t) indent
);
4206 s_indent
[indent
] = '\0';
4208 /* Print the loop's header. */
4209 fprintf (file
, "%sloop_%d\n", s_indent
, loop
->num
);
4211 /* Print the loop's body. */
4212 fprintf (file
, "%s{\n", s_indent
);
4214 if (bb
->loop_father
== loop
)
4216 /* Print the basic_block's header. */
4217 fprintf (file
, "%s bb_%d (preds = {", s_indent
, bb
->index
);
4218 print_pred_bbs (file
, bb
->pred
);
4219 fprintf (file
, "}, succs = {");
4220 print_succ_bbs (file
, bb
->succ
);
4221 fprintf (file
, "})\n");
4223 /* Print the basic_block's body. */
4224 fprintf (file
, "%s {\n", s_indent
);
4225 tree_dump_bb (bb
, file
, indent
+ 4);
4226 fprintf (file
, "%s }\n", s_indent
);
4229 print_loop (file
, loop
->inner
, indent
+ 2);
4230 fprintf (file
, "%s}\n", s_indent
);
4231 print_loop (file
, loop
->next
, indent
);
4235 /* Follow a CFG edge from the entry point of the program, and on entry
4236 of a loop, pretty print the loop structure on FILE. */
4239 print_loop_ir (FILE *file
)
4243 bb
= BASIC_BLOCK (0);
4244 if (bb
&& bb
->loop_father
)
4245 print_loop (file
, bb
->loop_father
, 0);
4249 /* Debugging loops structure at tree level. */
4252 debug_loop_ir (void)
4254 print_loop_ir (stderr
);
4258 /* Return true if BB ends with a call, possibly followed by some
4259 instructions that must stay with the call. Return false,
4263 tree_block_ends_with_call_p (basic_block bb
)
4265 block_stmt_iterator bsi
= bsi_last (bb
);
4266 tree t
= tsi_stmt (bsi
.tsi
);
4268 if (TREE_CODE (t
) == RETURN_EXPR
&& TREE_OPERAND (t
, 0))
4269 t
= TREE_OPERAND (t
, 0);
4271 if (TREE_CODE (t
) == MODIFY_EXPR
)
4272 t
= TREE_OPERAND (t
, 1);
4274 return TREE_CODE (t
) == CALL_EXPR
;
4278 /* Return true if BB ends with a conditional branch. Return false,
4282 tree_block_ends_with_condjump_p (basic_block bb
)
4284 tree stmt
= tsi_stmt (bsi_last (bb
).tsi
);
4285 return (TREE_CODE (stmt
) == COND_EXPR
);
4289 /* Return true if we need to add fake edge to exit at statement T.
4290 Helper function for tree_flow_call_edges_add. */
4293 need_fake_edge_p (tree t
)
4295 if (TREE_CODE (t
) == RETURN_EXPR
&& TREE_OPERAND (t
, 0))
4296 t
= TREE_OPERAND (t
, 0);
4298 if (TREE_CODE (t
) == MODIFY_EXPR
)
4299 t
= TREE_OPERAND (t
, 1);
4301 /* NORETURN and LONGJMP calls already have an edge to exit.
4302 CONST, PURE and ALWAYS_RETURN calls do not need one.
4303 We don't currently check for CONST and PURE here, although
4304 it would be a good idea, because those attributes are
4305 figured out from the RTL in mark_constant_function, and
4306 the counter incrementation code from -fprofile-arcs
4307 leads to different results from -fbranch-probabilities. */
4308 if (TREE_CODE (t
) == CALL_EXPR
4309 && !(call_expr_flags (t
) &
4310 (ECF_NORETURN
| ECF_LONGJMP
| ECF_ALWAYS_RETURN
)))
4313 if (TREE_CODE (t
) == ASM_EXPR
4314 && (ASM_VOLATILE_P (t
) || ASM_INPUT_P (t
)))
4321 /* Add fake edges to the function exit for any non constant and non
4322 noreturn calls, volatile inline assembly in the bitmap of blocks
4323 specified by BLOCKS or to the whole CFG if BLOCKS is zero. Return
4324 the number of blocks that were split.
4326 The goal is to expose cases in which entering a basic block does
4327 not imply that all subsequent instructions must be executed. */
4330 tree_flow_call_edges_add (sbitmap blocks
)
4333 int blocks_split
= 0;
4334 int last_bb
= last_basic_block
;
4335 bool check_last_block
= false;
4337 if (n_basic_blocks
== 0)
4341 check_last_block
= true;
4343 check_last_block
= TEST_BIT (blocks
, EXIT_BLOCK_PTR
->prev_bb
->index
);
4345 /* In the last basic block, before epilogue generation, there will be
4346 a fallthru edge to EXIT. Special care is required if the last insn
4347 of the last basic block is a call because make_edge folds duplicate
4348 edges, which would result in the fallthru edge also being marked
4349 fake, which would result in the fallthru edge being removed by
4350 remove_fake_edges, which would result in an invalid CFG.
4352 Moreover, we can't elide the outgoing fake edge, since the block
4353 profiler needs to take this into account in order to solve the minimal
4354 spanning tree in the case that the call doesn't return.
4356 Handle this by adding a dummy instruction in a new last basic block. */
4357 if (check_last_block
)
4359 basic_block bb
= EXIT_BLOCK_PTR
->prev_bb
;
4360 block_stmt_iterator bsi
= bsi_last (bb
);
4362 if (!bsi_end_p (bsi
))
4365 if (need_fake_edge_p (t
))
4369 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
4370 if (e
->dest
== EXIT_BLOCK_PTR
)
4372 bsi_insert_on_edge (e
, build_empty_stmt ());
4373 bsi_commit_edge_inserts ((int *)NULL
);
4379 /* Now add fake edges to the function exit for any non constant
4380 calls since there is no way that we can determine if they will
4382 for (i
= 0; i
< last_bb
; i
++)
4384 basic_block bb
= BASIC_BLOCK (i
);
4385 block_stmt_iterator bsi
;
4386 tree stmt
, last_stmt
;
4391 if (blocks
&& !TEST_BIT (blocks
, i
))
4394 bsi
= bsi_last (bb
);
4395 if (!bsi_end_p (bsi
))
4397 last_stmt
= bsi_stmt (bsi
);
4400 stmt
= bsi_stmt (bsi
);
4401 if (need_fake_edge_p (stmt
))
4404 /* The handling above of the final block before the
4405 epilogue should be enough to verify that there is
4406 no edge to the exit block in CFG already.
4407 Calling make_edge in such case would cause us to
4408 mark that edge as fake and remove it later. */
4409 #ifdef ENABLE_CHECKING
4410 if (stmt
== last_stmt
)
4411 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
4412 if (e
->dest
== EXIT_BLOCK_PTR
)
4416 /* Note that the following may create a new basic block
4417 and renumber the existing basic blocks. */
4418 if (stmt
!= last_stmt
)
4420 e
= split_block (bb
, stmt
);
4424 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
4428 while (!bsi_end_p (bsi
));
4433 verify_flow_info ();
4435 return blocks_split
;
4439 struct cfg_hooks tree_cfg_hooks
= {
4441 tree_verify_flow_info
,
4442 tree_dump_bb
, /* dump_bb */
4443 create_bb
, /* create_basic_block */
4444 tree_redirect_edge_and_branch
,/* redirect_edge_and_branch */
4445 tree_redirect_edge_and_branch_force
,/* redirect_edge_and_branch_force */
4446 remove_bb
, /* delete_basic_block */
4447 tree_split_block
, /* split_block */
4448 tree_move_block_after
, /* move_block_after */
4449 tree_can_merge_blocks_p
, /* can_merge_blocks_p */
4450 tree_merge_blocks
, /* merge_blocks */
4451 tree_predict_edge
, /* predict_edge */
4452 tree_predicted_by_p
, /* predicted_by_p */
4453 tree_can_duplicate_bb_p
, /* can_duplicate_block_p */
4454 tree_duplicate_bb
, /* duplicate_block */
4455 tree_split_edge
, /* split_edge */
4456 tree_make_forwarder_block
, /* make_forward_block */
4457 NULL
, /* tidy_fallthru_edge */
4458 tree_block_ends_with_call_p
, /* block_ends_with_call_p */
4459 tree_block_ends_with_condjump_p
, /* block_ends_with_condjump_p */
4460 tree_flow_call_edges_add
/* flow_call_edges_add */
4464 /* Split all critical edges. */
4467 split_critical_edges (void)
4474 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
4475 if (EDGE_CRITICAL_P (e
) && !(e
->flags
& EDGE_ABNORMAL
))
4482 struct tree_opt_pass pass_split_crit_edges
=
4486 split_critical_edges
, /* execute */
4489 0, /* static_pass_number */
4490 TV_TREE_SPLIT_EDGES
, /* tv_id */
4491 PROP_cfg
, /* properties required */
4492 PROP_no_crit_edges
, /* properties_provided */
4493 0, /* properties_destroyed */
4494 0, /* todo_flags_start */
4495 0, /* todo_flags_finish */
4498 /* Emit return warnings. */
4501 execute_warn_function_return (void)
4507 if (warn_missing_noreturn
4508 && !TREE_THIS_VOLATILE (cfun
->decl
)
4509 && EXIT_BLOCK_PTR
->pred
== NULL
4510 && !lang_hooks
.function
.missing_noreturn_ok_p (cfun
->decl
))
4511 warning ("%Jfunction might be possible candidate for attribute `noreturn'",
4514 /* If we have a path to EXIT, then we do return. */
4515 if (TREE_THIS_VOLATILE (cfun
->decl
)
4516 && EXIT_BLOCK_PTR
->pred
!= NULL
)
4519 for (e
= EXIT_BLOCK_PTR
->pred
; e
; e
= e
->pred_next
)
4521 last
= last_stmt (e
->src
);
4522 if (TREE_CODE (last
) == RETURN_EXPR
4523 && (locus
= EXPR_LOCUS (last
)) != NULL
)
4527 locus
= &cfun
->function_end_locus
;
4528 warning ("%H`noreturn' function does return", locus
);
4531 /* If we see "return;" in some basic block, then we do reach the end
4532 without returning a value. */
4533 else if (warn_return_type
4534 && EXIT_BLOCK_PTR
->pred
!= NULL
4535 && !VOID_TYPE_P (TREE_TYPE (TREE_TYPE (cfun
->decl
))))
4537 for (e
= EXIT_BLOCK_PTR
->pred
; e
; e
= e
->pred_next
)
4539 tree last
= last_stmt (e
->src
);
4540 if (TREE_CODE (last
) == RETURN_EXPR
4541 && TREE_OPERAND (last
, 0) == NULL
)
4543 locus
= EXPR_LOCUS (last
);
4545 locus
= &cfun
->function_end_locus
;
4546 warning ("%Hcontrol reaches end of non-void function", locus
);
4554 /* Given a basic block B which ends with a conditional and has
4555 precisely two successors, determine which of the edges is taken if
4556 the conditional is true and which is taken if the conditional is
4557 false. Set TRUE_EDGE and FALSE_EDGE appropriately. */
4560 extract_true_false_edges_from_block (basic_block b
,
4566 if (e
->flags
& EDGE_TRUE_VALUE
)
4569 *false_edge
= e
->succ_next
;
4574 *true_edge
= e
->succ_next
;
4578 struct tree_opt_pass pass_warn_function_return
=
4582 execute_warn_function_return
, /* execute */
4585 0, /* static_pass_number */
4587 PROP_ssa
, /* properties_required */
4588 0, /* properties_provided */
4589 0, /* properties_destroyed */
4590 0, /* todo_flags_start */
4591 0 /* todo_flags_finish */
4594 #include "gt-tree-cfg.h"