1 /* Control flow functions for trees.
2 Copyright (C) 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
3 Contributed by Diego Novillo <dnovillo@redhat.com>
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 GCC is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to
19 the Free Software Foundation, 59 Temple Place - Suite 330,
20 Boston, MA 02111-1307, USA. */
24 #include "coretypes.h"
29 #include "hard-reg-set.h"
30 #include "basic-block.h"
37 #include "langhooks.h"
38 #include "diagnostic.h"
39 #include "tree-flow.h"
41 #include "tree-dump.h"
42 #include "tree-pass.h"
47 /* This file contains functions for building the Control Flow Graph (CFG)
48 for a function tree. */
50 /* Local declarations. */
52 /* Initial capacity for the basic block array. */
53 static const int initial_cfg_capacity
= 20;
55 /* Mapping of labels to their associated blocks. This can greatly speed up
56 building of the CFG in code with lots of gotos. */
57 static GTY(()) varray_type label_to_block_map
;
62 long num_merged_labels
;
65 static struct cfg_stats_d cfg_stats
;
67 /* Nonzero if we found a computed goto while building basic blocks. */
68 static bool found_computed_goto
;
70 /* Basic blocks and flowgraphs. */
71 static basic_block
create_bb (void *, void *, basic_block
);
72 static void create_block_annotation (basic_block
);
73 static void free_blocks_annotations (void);
74 static void clear_blocks_annotations (void);
75 static void make_blocks (tree
);
76 static void factor_computed_gotos (void);
79 static void make_edges (void);
80 static void make_ctrl_stmt_edges (basic_block
);
81 static void make_exit_edges (basic_block
);
82 static void make_cond_expr_edges (basic_block
);
83 static void make_switch_expr_edges (basic_block
);
84 static void make_goto_expr_edges (basic_block
);
85 static edge
tree_redirect_edge_and_branch (edge
, basic_block
);
86 static edge
tree_try_redirect_by_replacing_jump (edge
, basic_block
);
87 static void split_critical_edges (void);
89 /* Various helpers. */
90 static inline bool stmt_starts_bb_p (tree
, tree
);
91 static int tree_verify_flow_info (void);
92 static void tree_make_forwarder_block (edge
);
93 static bool thread_jumps (void);
94 static bool tree_forwarder_block_p (basic_block
);
95 static void bsi_commit_edge_inserts_1 (edge e
);
96 static void tree_cfg2vcg (FILE *);
98 /* Flowgraph optimization and cleanup. */
99 static void tree_merge_blocks (basic_block
, basic_block
);
100 static bool tree_can_merge_blocks_p (basic_block
, basic_block
);
101 static void remove_bb (basic_block
);
102 static void group_case_labels (void);
103 static void cleanup_dead_labels (void);
104 static bool cleanup_control_flow (void);
105 static bool cleanup_control_expr_graph (basic_block
, block_stmt_iterator
);
106 static edge
find_taken_edge_cond_expr (basic_block
, tree
);
107 static edge
find_taken_edge_switch_expr (basic_block
, tree
);
108 static tree
find_case_label_for_value (tree
, tree
);
109 static bool phi_alternatives_equal (basic_block
, edge
, edge
);
112 /*---------------------------------------------------------------------------
114 ---------------------------------------------------------------------------*/
116 /* Entry point to the CFG builder for trees. TP points to the list of
117 statements to be added to the flowgraph. */
120 build_tree_cfg (tree
*tp
)
122 /* Register specific tree functions. */
123 tree_register_cfg_hooks ();
125 /* Initialize rbi_pool. */
128 /* Initialize the basic block array. */
131 last_basic_block
= 0;
132 VARRAY_BB_INIT (basic_block_info
, initial_cfg_capacity
, "basic_block_info");
133 memset ((void *) &cfg_stats
, 0, sizeof (cfg_stats
));
135 /* Build a mapping of labels to their associated blocks. */
136 VARRAY_BB_INIT (label_to_block_map
, initial_cfg_capacity
,
137 "label to block map");
139 ENTRY_BLOCK_PTR
->next_bb
= EXIT_BLOCK_PTR
;
140 EXIT_BLOCK_PTR
->prev_bb
= ENTRY_BLOCK_PTR
;
142 found_computed_goto
= 0;
145 /* Computed gotos are hell to deal with, especially if there are
146 lots of them with a large number of destinations. So we factor
147 them to a common computed goto location before we build the
148 edge list. After we convert back to normal form, we will un-factor
149 the computed gotos since factoring introduces an unwanted jump. */
150 if (found_computed_goto
)
151 factor_computed_gotos ();
153 /* Make sure there is always at least one block, even if its empty. */
154 if (n_basic_blocks
== 0)
155 create_empty_bb (ENTRY_BLOCK_PTR
);
157 create_block_annotation (ENTRY_BLOCK_PTR
);
158 create_block_annotation (EXIT_BLOCK_PTR
);
160 /* Adjust the size of the array. */
161 VARRAY_GROW (basic_block_info
, n_basic_blocks
);
163 /* To speed up statement iterator walks, we first purge dead labels. */
164 cleanup_dead_labels ();
166 /* Group case nodes to reduce the number of edges.
167 We do this after cleaning up dead labels because otherwise we miss
168 a lot of obvious case merging opportunities. */
169 group_case_labels ();
171 /* Create the edges of the flowgraph. */
174 /* Debugging dumps. */
176 /* Write the flowgraph to a VCG file. */
178 int local_dump_flags
;
179 FILE *dump_file
= dump_begin (TDI_vcg
, &local_dump_flags
);
182 tree_cfg2vcg (dump_file
);
183 dump_end (TDI_vcg
, dump_file
);
187 /* Dump a textual representation of the flowgraph. */
189 dump_tree_cfg (dump_file
, dump_flags
);
193 execute_build_cfg (void)
195 build_tree_cfg (&DECL_SAVED_TREE (current_function_decl
));
198 struct tree_opt_pass pass_build_cfg
=
202 execute_build_cfg
, /* execute */
205 0, /* static_pass_number */
206 TV_TREE_CFG
, /* tv_id */
207 PROP_gimple_leh
, /* properties_required */
208 PROP_cfg
, /* properties_provided */
209 0, /* properties_destroyed */
210 0, /* todo_flags_start */
211 TODO_verify_stmts
/* todo_flags_finish */
214 /* Search the CFG for any computed gotos. If found, factor them to a
215 common computed goto site. Also record the location of that site so
216 that we can un-factor the gotos after we have converted back to
220 factor_computed_gotos (void)
223 tree factored_label_decl
= NULL
;
225 tree factored_computed_goto_label
= NULL
;
226 tree factored_computed_goto
= NULL
;
228 /* We know there are one or more computed gotos in this function.
229 Examine the last statement in each basic block to see if the block
230 ends with a computed goto. */
234 block_stmt_iterator bsi
= bsi_last (bb
);
239 last
= bsi_stmt (bsi
);
241 /* Ignore the computed goto we create when we factor the original
243 if (last
== factored_computed_goto
)
246 /* If the last statement is a computed goto, factor it. */
247 if (computed_goto_p (last
))
251 /* The first time we find a computed goto we need to create
252 the factored goto block and the variable each original
253 computed goto will use for their goto destination. */
254 if (! factored_computed_goto
)
256 basic_block new_bb
= create_empty_bb (bb
);
257 block_stmt_iterator new_bsi
= bsi_start (new_bb
);
259 /* Create the destination of the factored goto. Each original
260 computed goto will put its desired destination into this
261 variable and jump to the label we create immediately
263 var
= create_tmp_var (ptr_type_node
, "gotovar");
265 /* Build a label for the new block which will contain the
266 factored computed goto. */
267 factored_label_decl
= create_artificial_label ();
268 factored_computed_goto_label
269 = build1 (LABEL_EXPR
, void_type_node
, factored_label_decl
);
270 bsi_insert_after (&new_bsi
, factored_computed_goto_label
,
273 /* Build our new computed goto. */
274 factored_computed_goto
= build1 (GOTO_EXPR
, void_type_node
, var
);
275 bsi_insert_after (&new_bsi
, factored_computed_goto
,
279 /* Copy the original computed goto's destination into VAR. */
280 assignment
= build (MODIFY_EXPR
, ptr_type_node
,
281 var
, GOTO_DESTINATION (last
));
282 bsi_insert_before (&bsi
, assignment
, BSI_SAME_STMT
);
284 /* And re-vector the computed goto to the new destination. */
285 GOTO_DESTINATION (last
) = factored_label_decl
;
291 /* Create annotations for a single basic block. */
294 create_block_annotation (basic_block bb
)
296 /* Verify that the tree_annotations field is clear. */
297 if (bb
->tree_annotations
)
299 bb
->tree_annotations
= ggc_alloc_cleared (sizeof (struct bb_ann_d
));
303 /* Free the annotations for all the basic blocks. */
305 static void free_blocks_annotations (void)
307 clear_blocks_annotations ();
311 /* Clear the annotations for all the basic blocks. */
314 clear_blocks_annotations (void)
318 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
, NULL
, next_bb
)
319 bb
->tree_annotations
= NULL
;
323 /* Build a flowgraph for the statement_list STMT_LIST. */
326 make_blocks (tree stmt_list
)
328 tree_stmt_iterator i
= tsi_start (stmt_list
);
330 bool start_new_block
= true;
331 bool first_stmt_of_list
= true;
332 basic_block bb
= ENTRY_BLOCK_PTR
;
334 while (!tsi_end_p (i
))
341 /* If the statement starts a new basic block or if we have determined
342 in a previous pass that we need to create a new block for STMT, do
344 if (start_new_block
|| stmt_starts_bb_p (stmt
, prev_stmt
))
346 if (!first_stmt_of_list
)
347 stmt_list
= tsi_split_statement_list_before (&i
);
348 bb
= create_basic_block (stmt_list
, NULL
, bb
);
349 start_new_block
= false;
352 /* Now add STMT to BB and create the subgraphs for special statement
354 set_bb_for_stmt (stmt
, bb
);
356 if (computed_goto_p (stmt
))
357 found_computed_goto
= true;
359 /* If STMT is a basic block terminator, set START_NEW_BLOCK for the
361 if (stmt_ends_bb_p (stmt
))
362 start_new_block
= true;
365 first_stmt_of_list
= false;
370 /* Create and return a new empty basic block after bb AFTER. */
373 create_bb (void *h
, void *e
, basic_block after
)
380 /* Create and initialize a new basic block. */
382 memset (bb
, 0, sizeof (*bb
));
384 bb
->index
= last_basic_block
;
386 bb
->stmt_list
= h
? h
: alloc_stmt_list ();
388 /* Add the new block to the linked list of blocks. */
389 link_block (bb
, after
);
391 /* Grow the basic block array if needed. */
392 if ((size_t) last_basic_block
== VARRAY_SIZE (basic_block_info
))
394 size_t new_size
= last_basic_block
+ (last_basic_block
+ 3) / 4;
395 VARRAY_GROW (basic_block_info
, new_size
);
398 /* Add the newly created block to the array. */
399 BASIC_BLOCK (last_basic_block
) = bb
;
401 create_block_annotation (bb
);
406 initialize_bb_rbi (bb
);
411 /*---------------------------------------------------------------------------
413 ---------------------------------------------------------------------------*/
415 /* Join all the blocks in the flowgraph. */
423 /* Create an edge from entry to the first block with executable
425 make_edge (ENTRY_BLOCK_PTR
, BASIC_BLOCK (0), EDGE_FALLTHRU
);
427 /* Traverse basic block array placing edges. */
430 tree first
= first_stmt (bb
);
431 tree last
= last_stmt (bb
);
435 /* Edges for statements that always alter flow control. */
436 if (is_ctrl_stmt (last
))
437 make_ctrl_stmt_edges (bb
);
439 /* Edges for statements that sometimes alter flow control. */
440 if (is_ctrl_altering_stmt (last
))
441 make_exit_edges (bb
);
444 /* Finally, if no edges were created above, this is a regular
445 basic block that only needs a fallthru edge. */
446 if (bb
->succ
== NULL
)
447 make_edge (bb
, bb
->next_bb
, EDGE_FALLTHRU
);
450 /* If there is a fallthru edge to exit out of the last block, transform it
451 to a return statement. */
452 for (e
= EXIT_BLOCK_PTR
->prev_bb
->succ
; e
; e
= e
->succ_next
)
453 if (e
->flags
& EDGE_FALLTHRU
)
456 if (e
&& e
->dest
== EXIT_BLOCK_PTR
)
458 block_stmt_iterator bsi
;
459 basic_block ret_bb
= EXIT_BLOCK_PTR
->prev_bb
;
462 /* If E->SRC ends with a call that has an abnormal edge (for EH or
463 nonlocal goto), then we will need to split the edge to insert
464 an explicit return statement. */
465 if (e
!= ret_bb
->succ
|| e
->succ_next
)
467 ret_bb
= split_edge (e
);
470 e
->flags
&= ~EDGE_FALLTHRU
;
472 x
= build (RETURN_EXPR
, void_type_node
, NULL_TREE
);
473 bsi
= bsi_last (ret_bb
);
474 bsi_insert_after (&bsi
, x
, BSI_NEW_STMT
);
477 /* We do not care about fake edges, so remove any that the CFG
478 builder inserted for completeness. */
479 remove_fake_edges ();
481 /* Clean up the graph and warn for unreachable code. */
486 /* Create edges for control statement at basic block BB. */
489 make_ctrl_stmt_edges (basic_block bb
)
491 tree last
= last_stmt (bb
);
492 tree first
= first_stmt (bb
);
494 #if defined ENABLE_CHECKING
495 if (last
== NULL_TREE
)
499 if (TREE_CODE (first
) == LABEL_EXPR
500 && DECL_NONLOCAL (LABEL_EXPR_LABEL (first
)))
501 make_edge (ENTRY_BLOCK_PTR
, bb
, EDGE_ABNORMAL
);
503 switch (TREE_CODE (last
))
506 make_goto_expr_edges (bb
);
510 make_edge (bb
, EXIT_BLOCK_PTR
, 0);
514 make_cond_expr_edges (bb
);
518 make_switch_expr_edges (bb
);
522 make_eh_edges (last
);
523 /* Yet another NORETURN hack. */
524 if (bb
->succ
== NULL
)
525 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
534 /* Create exit edges for statements in block BB that alter the flow of
535 control. Statements that alter the control flow are 'goto', 'return'
536 and calls to non-returning functions. */
539 make_exit_edges (basic_block bb
)
541 tree last
= last_stmt (bb
);
543 if (last
== NULL_TREE
)
546 switch (TREE_CODE (last
))
549 /* If this function receives a nonlocal goto, then we need to
550 make edges from this call site to all the nonlocal goto
552 if (TREE_SIDE_EFFECTS (last
)
553 && current_function_has_nonlocal_label
)
554 make_goto_expr_edges (bb
);
556 /* If this statement has reachable exception handlers, then
557 create abnormal edges to them. */
558 make_eh_edges (last
);
560 /* Some calls are known not to return. For such calls we create
563 We really need to revamp how we build edges so that it's not
564 such a bloody pain to avoid creating edges for this case since
565 all we do is remove these edges when we're done building the
567 if (call_expr_flags (last
) & (ECF_NORETURN
| ECF_LONGJMP
))
569 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
573 /* Don't forget the fall-thru edge. */
574 make_edge (bb
, bb
->next_bb
, EDGE_FALLTHRU
);
578 /* A MODIFY_EXPR may have a CALL_EXPR on its RHS and the CALL_EXPR
579 may have an abnormal edge. Search the RHS for this case and
580 create any required edges. */
581 if (TREE_CODE (TREE_OPERAND (last
, 1)) == CALL_EXPR
582 && TREE_SIDE_EFFECTS (TREE_OPERAND (last
, 1))
583 && current_function_has_nonlocal_label
)
584 make_goto_expr_edges (bb
);
586 make_eh_edges (last
);
587 make_edge (bb
, bb
->next_bb
, EDGE_FALLTHRU
);
596 /* Create the edges for a COND_EXPR starting at block BB.
597 At this point, both clauses must contain only simple gotos. */
600 make_cond_expr_edges (basic_block bb
)
602 tree entry
= last_stmt (bb
);
603 basic_block then_bb
, else_bb
;
604 tree then_label
, else_label
;
606 #if defined ENABLE_CHECKING
607 if (entry
== NULL_TREE
|| TREE_CODE (entry
) != COND_EXPR
)
611 /* Entry basic blocks for each component. */
612 then_label
= GOTO_DESTINATION (COND_EXPR_THEN (entry
));
613 else_label
= GOTO_DESTINATION (COND_EXPR_ELSE (entry
));
614 then_bb
= label_to_block (then_label
);
615 else_bb
= label_to_block (else_label
);
617 make_edge (bb
, then_bb
, EDGE_TRUE_VALUE
);
618 make_edge (bb
, else_bb
, EDGE_FALSE_VALUE
);
622 /* Create the edges for a SWITCH_EXPR starting at block BB.
623 At this point, the switch body has been lowered and the
624 SWITCH_LABELS filled in, so this is in effect a multi-way branch. */
627 make_switch_expr_edges (basic_block bb
)
629 tree entry
= last_stmt (bb
);
633 vec
= SWITCH_LABELS (entry
);
634 n
= TREE_VEC_LENGTH (vec
);
636 for (i
= 0; i
< n
; ++i
)
638 tree lab
= CASE_LABEL (TREE_VEC_ELT (vec
, i
));
639 basic_block label_bb
= label_to_block (lab
);
640 make_edge (bb
, label_bb
, 0);
645 /* Return the basic block holding label DEST. */
648 label_to_block (tree dest
)
650 return VARRAY_BB (label_to_block_map
, LABEL_DECL_UID (dest
));
654 /* Create edges for a goto statement at block BB. */
657 make_goto_expr_edges (basic_block bb
)
660 basic_block target_bb
;
662 block_stmt_iterator last
= bsi_last (bb
);
664 goto_t
= bsi_stmt (last
);
666 /* If the last statement is not a GOTO (i.e., it is a RETURN_EXPR,
667 CALL_EXPR or MODIFY_EXPR), then the edge is an abnormal edge resulting
668 from a nonlocal goto. */
669 if (TREE_CODE (goto_t
) != GOTO_EXPR
)
671 dest
= error_mark_node
;
676 dest
= GOTO_DESTINATION (goto_t
);
679 /* A GOTO to a local label creates normal edges. */
680 if (simple_goto_p (goto_t
))
682 edge e
= make_edge (bb
, label_to_block (dest
), EDGE_FALLTHRU
);
683 e
->goto_locus
= EXPR_LOCUS (goto_t
);
688 /* Nothing more to do for nonlocal gotos. */
689 if (TREE_CODE (dest
) == LABEL_DECL
)
692 /* Computed gotos remain. */
695 /* Look for the block starting with the destination label. In the
696 case of a computed goto, make an edge to any label block we find
698 FOR_EACH_BB (target_bb
)
700 block_stmt_iterator bsi
;
702 for (bsi
= bsi_start (target_bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
704 tree target
= bsi_stmt (bsi
);
706 if (TREE_CODE (target
) != LABEL_EXPR
)
710 /* Computed GOTOs. Make an edge to every label block that has
711 been marked as a potential target for a computed goto. */
712 (FORCED_LABEL (LABEL_EXPR_LABEL (target
)) && for_call
== 0)
713 /* Nonlocal GOTO target. Make an edge to every label block
714 that has been marked as a potential target for a nonlocal
716 || (DECL_NONLOCAL (LABEL_EXPR_LABEL (target
)) && for_call
== 1))
718 make_edge (bb
, target_bb
, EDGE_ABNORMAL
);
724 /* Degenerate case of computed goto with no labels. */
725 if (!for_call
&& !bb
->succ
)
726 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
730 /*---------------------------------------------------------------------------
732 ---------------------------------------------------------------------------*/
734 /* Remove unreachable blocks and other miscellaneous clean up work. */
737 cleanup_tree_cfg (void)
739 bool something_changed
= true;
741 timevar_push (TV_TREE_CLEANUP_CFG
);
743 /* These three transformations can cascade, so we iterate on them until
745 while (something_changed
)
747 something_changed
= cleanup_control_flow ();
748 something_changed
|= thread_jumps ();
749 something_changed
|= delete_unreachable_blocks ();
752 /* Merging the blocks creates no new opportunities for the other
753 optimizations, so do it here. */
758 #ifdef ENABLE_CHECKING
761 timevar_pop (TV_TREE_CLEANUP_CFG
);
765 /* Cleanup useless labels in basic blocks. This is something we wish
766 to do early because it allows us to group case labels before creating
767 the edges for the CFG, and it speeds up block statement iterators in
769 We only run this pass once, running it more than once is probably not
772 /* A map from basic block index to the leading label of that block. */
773 static tree
*label_for_bb
;
775 /* Callback for for_each_eh_region. Helper for cleanup_dead_labels. */
777 update_eh_label (struct eh_region
*region
)
779 tree old_label
= get_eh_region_tree_label (region
);
782 tree new_label
= label_for_bb
[label_to_block (old_label
)->index
];
783 set_eh_region_tree_label (region
, new_label
);
787 /* Cleanup redundant labels. This is a three-steo process:
788 1) Find the leading label for each block.
789 2) Redirect all references to labels to the leading labels.
790 3) Cleanup all useless labels. */
793 cleanup_dead_labels (void)
796 label_for_bb
= xcalloc (last_basic_block
, sizeof (tree
));
798 /* Find a suitable label for each block. We use the first user-defined
799 label is there is one, or otherwise just the first label we see. */
802 block_stmt_iterator i
;
804 for (i
= bsi_start (bb
); !bsi_end_p (i
); bsi_next (&i
))
806 tree label
, stmt
= bsi_stmt (i
);
808 if (TREE_CODE (stmt
) != LABEL_EXPR
)
811 label
= LABEL_EXPR_LABEL (stmt
);
813 /* If we have not yet seen a label for the current block,
814 remember this one and see if there are more labels. */
815 if (! label_for_bb
[bb
->index
])
817 label_for_bb
[bb
->index
] = label
;
821 /* If we did see a label for the current block already, but it
822 is an artificially created label, replace it if the current
823 label is a user defined label. */
824 if (! DECL_ARTIFICIAL (label
)
825 && DECL_ARTIFICIAL (label_for_bb
[bb
->index
]))
827 label_for_bb
[bb
->index
] = label
;
833 /* Now redirect all jumps/branches to the selected label.
834 First do so for each block ending in a control statement. */
837 tree stmt
= last_stmt (bb
);
841 switch (TREE_CODE (stmt
))
845 tree true_branch
, false_branch
;
846 basic_block true_bb
, false_bb
;
848 true_branch
= COND_EXPR_THEN (stmt
);
849 false_branch
= COND_EXPR_ELSE (stmt
);
850 true_bb
= label_to_block (GOTO_DESTINATION (true_branch
));
851 false_bb
= label_to_block (GOTO_DESTINATION (false_branch
));
853 GOTO_DESTINATION (true_branch
) = label_for_bb
[true_bb
->index
];
854 GOTO_DESTINATION (false_branch
) = label_for_bb
[false_bb
->index
];
862 tree vec
= SWITCH_LABELS (stmt
);
863 size_t n
= TREE_VEC_LENGTH (vec
);
865 /* Replace all destination labels. */
866 for (i
= 0; i
< n
; ++i
)
868 tree label
= CASE_LABEL (TREE_VEC_ELT (vec
, i
));
870 CASE_LABEL (TREE_VEC_ELT (vec
, i
)) =
871 label_for_bb
[label_to_block (label
)->index
];
877 /* We have to handle GOTO_EXPRs until they're removed, and we don't
878 remove them until after we've created the CFG edges. */
881 tree label
= GOTO_DESTINATION (stmt
);
882 if (! computed_goto_p (stmt
))
883 GOTO_DESTINATION (stmt
) =
884 label_for_bb
[label_to_block (label
)->index
];
893 for_each_eh_region (update_eh_label
);
895 /* Finally, purge dead labels. All user-defined labels and labels that
896 can be the target of non-local gotos are preserved. */
899 block_stmt_iterator i
;
900 tree label_for_this_bb
= label_for_bb
[bb
->index
];
902 if (! label_for_this_bb
)
905 for (i
= bsi_start (bb
); !bsi_end_p (i
); )
907 tree label
, stmt
= bsi_stmt (i
);
909 if (TREE_CODE (stmt
) != LABEL_EXPR
)
912 label
= LABEL_EXPR_LABEL (stmt
);
914 if (label
== label_for_this_bb
915 || ! DECL_ARTIFICIAL (label
)
916 || DECL_NONLOCAL (label
))
926 /* Look for blocks ending in a multiway branch (a SWITCH_EXPR in GIMPLE),
927 and scan the sorted vector of cases. Combine the ones jumping to the
929 Eg. three separate entries 1: 2: 3: become one entry 1..3: */
932 group_case_labels (void)
938 tree stmt
= last_stmt (bb
);
939 if (stmt
&& TREE_CODE (stmt
) == SWITCH_EXPR
)
941 tree labels
= SWITCH_LABELS (stmt
);
942 int old_size
= TREE_VEC_LENGTH (labels
);
943 int i
, j
, new_size
= old_size
;
945 /* Look for possible opportunities to merge cases.
946 Ignore the last element of the label vector because it
947 must be the default case. */
949 while (i
< old_size
- 2)
951 tree base_case
, base_label
, base_high
, type
;
952 base_case
= TREE_VEC_ELT (labels
, i
);
957 type
= TREE_TYPE (CASE_LOW (base_case
));
958 base_label
= CASE_LABEL (base_case
);
959 base_high
= CASE_HIGH (base_case
) ?
960 CASE_HIGH (base_case
) : CASE_LOW (base_case
);
962 /* Try to merge case labels. Break out when we reach the end
963 of the label vector or when we cannot merge the next case
964 label with the current one. */
965 while (i
< old_size
- 2)
967 tree merge_case
= TREE_VEC_ELT (labels
, ++i
);
968 tree merge_label
= CASE_LABEL (merge_case
);
969 tree t
= int_const_binop (PLUS_EXPR
, base_high
,
970 integer_one_node
, 1);
972 /* Merge the cases if they jump to the same place,
973 and their ranges are consecutive. */
974 if (merge_label
== base_label
975 && tree_int_cst_equal (CASE_LOW (merge_case
), t
))
977 base_high
= CASE_HIGH (merge_case
) ?
978 CASE_HIGH (merge_case
) : CASE_LOW (merge_case
);
979 CASE_HIGH (base_case
) = base_high
;
980 TREE_VEC_ELT (labels
, i
) = NULL_TREE
;
988 /* Compress the case labels in the label vector, and adjust the
989 length of the vector. */
990 for (i
= 0, j
= 0; i
< new_size
; i
++)
992 while (! TREE_VEC_ELT (labels
, j
))
994 TREE_VEC_ELT (labels
, i
) = TREE_VEC_ELT (labels
, j
++);
996 TREE_VEC_LENGTH (labels
) = new_size
;
1001 /* Checks whether we can merge block B into block A. */
1004 tree_can_merge_blocks_p (basic_block a
, basic_block b
)
1007 block_stmt_iterator bsi
;
1010 || a
->succ
->succ_next
)
1013 if (a
->succ
->flags
& EDGE_ABNORMAL
)
1016 if (a
->succ
->dest
!= b
)
1019 if (b
== EXIT_BLOCK_PTR
)
1022 if (b
->pred
->pred_next
)
1025 /* If A ends by a statement causing exceptions or something similar, we
1026 cannot merge the blocks. */
1027 stmt
= last_stmt (a
);
1028 if (stmt
&& stmt_ends_bb_p (stmt
))
1031 /* Do not allow a block with only a non-local label to be merged. */
1032 if (stmt
&& TREE_CODE (stmt
) == LABEL_EXPR
1033 && DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt
)))
1036 /* There may be no phi nodes at the start of b. Most of these degenerate
1037 phi nodes should be cleaned up by kill_redundant_phi_nodes. */
1041 /* Do not remove user labels. */
1042 for (bsi
= bsi_start (b
); !bsi_end_p (bsi
); bsi_next (&bsi
))
1044 stmt
= bsi_stmt (bsi
);
1045 if (TREE_CODE (stmt
) != LABEL_EXPR
)
1047 if (!DECL_ARTIFICIAL (LABEL_EXPR_LABEL (stmt
)))
1055 /* Merge block B into block A. */
1058 tree_merge_blocks (basic_block a
, basic_block b
)
1060 block_stmt_iterator bsi
;
1061 tree_stmt_iterator last
;
1064 fprintf (dump_file
, "Merging blocks %d and %d\n", a
->index
, b
->index
);
1066 /* Ensure that B follows A. */
1067 move_block_after (b
, a
);
1069 if (!(a
->succ
->flags
& EDGE_FALLTHRU
))
1073 && stmt_ends_bb_p (last_stmt (a
)))
1076 /* Remove labels from B and set bb_for_stmt to A for other statements. */
1077 for (bsi
= bsi_start (b
); !bsi_end_p (bsi
);)
1079 if (TREE_CODE (bsi_stmt (bsi
)) == LABEL_EXPR
)
1083 set_bb_for_stmt (bsi_stmt (bsi
), a
);
1088 /* Merge the chains. */
1089 last
= tsi_last (a
->stmt_list
);
1090 tsi_link_after (&last
, b
->stmt_list
, TSI_NEW_STMT
);
1091 b
->stmt_list
= NULL
;
1095 /* Walk the function tree removing unnecessary statements.
1097 * Empty statement nodes are removed
1099 * Unnecessary TRY_FINALLY and TRY_CATCH blocks are removed
1101 * Unnecessary COND_EXPRs are removed
1103 * Some unnecessary BIND_EXPRs are removed
1105 Clearly more work could be done. The trick is doing the analysis
1106 and removal fast enough to be a net improvement in compile times.
1108 Note that when we remove a control structure such as a COND_EXPR
1109 BIND_EXPR, or TRY block, we will need to repeat this optimization pass
1110 to ensure we eliminate all the useless code. */
1121 static void remove_useless_stmts_1 (tree
*, struct rus_data
*);
1124 remove_useless_stmts_warn_notreached (tree stmt
)
1126 if (EXPR_LOCUS (stmt
))
1128 warning ("%Hwill never be executed", EXPR_LOCUS (stmt
));
1132 switch (TREE_CODE (stmt
))
1134 case STATEMENT_LIST
:
1136 tree_stmt_iterator i
;
1137 for (i
= tsi_start (stmt
); !tsi_end_p (i
); tsi_next (&i
))
1138 if (remove_useless_stmts_warn_notreached (tsi_stmt (i
)))
1144 if (remove_useless_stmts_warn_notreached (COND_EXPR_COND (stmt
)))
1146 if (remove_useless_stmts_warn_notreached (COND_EXPR_THEN (stmt
)))
1148 if (remove_useless_stmts_warn_notreached (COND_EXPR_ELSE (stmt
)))
1152 case TRY_FINALLY_EXPR
:
1153 case TRY_CATCH_EXPR
:
1154 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt
, 0)))
1156 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt
, 1)))
1161 return remove_useless_stmts_warn_notreached (CATCH_BODY (stmt
));
1162 case EH_FILTER_EXPR
:
1163 return remove_useless_stmts_warn_notreached (EH_FILTER_FAILURE (stmt
));
1165 return remove_useless_stmts_warn_notreached (BIND_EXPR_BLOCK (stmt
));
1168 /* Not a live container. */
1176 remove_useless_stmts_cond (tree
*stmt_p
, struct rus_data
*data
)
1178 tree then_clause
, else_clause
, cond
;
1179 bool save_has_label
, then_has_label
, else_has_label
;
1181 save_has_label
= data
->has_label
;
1182 data
->has_label
= false;
1183 data
->last_goto
= NULL
;
1185 remove_useless_stmts_1 (&COND_EXPR_THEN (*stmt_p
), data
);
1187 then_has_label
= data
->has_label
;
1188 data
->has_label
= false;
1189 data
->last_goto
= NULL
;
1191 remove_useless_stmts_1 (&COND_EXPR_ELSE (*stmt_p
), data
);
1193 else_has_label
= data
->has_label
;
1194 data
->has_label
= save_has_label
| then_has_label
| else_has_label
;
1197 then_clause
= COND_EXPR_THEN (*stmt_p
);
1198 else_clause
= COND_EXPR_ELSE (*stmt_p
);
1199 cond
= COND_EXPR_COND (*stmt_p
);
1201 /* If neither arm does anything at all, we can remove the whole IF. */
1202 if (!TREE_SIDE_EFFECTS (then_clause
) && !TREE_SIDE_EFFECTS (else_clause
))
1204 *stmt_p
= build_empty_stmt ();
1205 data
->repeat
= true;
1208 /* If there are no reachable statements in an arm, then we can
1209 zap the entire conditional. */
1210 else if (integer_nonzerop (cond
) && !else_has_label
)
1212 if (warn_notreached
)
1213 remove_useless_stmts_warn_notreached (else_clause
);
1214 *stmt_p
= then_clause
;
1215 data
->repeat
= true;
1217 else if (integer_zerop (cond
) && !then_has_label
)
1219 if (warn_notreached
)
1220 remove_useless_stmts_warn_notreached (then_clause
);
1221 *stmt_p
= else_clause
;
1222 data
->repeat
= true;
1225 /* Check a couple of simple things on then/else with single stmts. */
1228 tree then_stmt
= expr_only (then_clause
);
1229 tree else_stmt
= expr_only (else_clause
);
1231 /* Notice branches to a common destination. */
1232 if (then_stmt
&& else_stmt
1233 && TREE_CODE (then_stmt
) == GOTO_EXPR
1234 && TREE_CODE (else_stmt
) == GOTO_EXPR
1235 && (GOTO_DESTINATION (then_stmt
) == GOTO_DESTINATION (else_stmt
)))
1237 *stmt_p
= then_stmt
;
1238 data
->repeat
= true;
1241 /* If the THEN/ELSE clause merely assigns a value to a variable or
1242 parameter which is already known to contain that value, then
1243 remove the useless THEN/ELSE clause. */
1244 else if (TREE_CODE (cond
) == VAR_DECL
|| TREE_CODE (cond
) == PARM_DECL
)
1247 && TREE_CODE (else_stmt
) == MODIFY_EXPR
1248 && TREE_OPERAND (else_stmt
, 0) == cond
1249 && integer_zerop (TREE_OPERAND (else_stmt
, 1)))
1250 COND_EXPR_ELSE (*stmt_p
) = alloc_stmt_list ();
1252 else if ((TREE_CODE (cond
) == EQ_EXPR
|| TREE_CODE (cond
) == NE_EXPR
)
1253 && (TREE_CODE (TREE_OPERAND (cond
, 0)) == VAR_DECL
1254 || TREE_CODE (TREE_OPERAND (cond
, 0)) == PARM_DECL
)
1255 && TREE_CONSTANT (TREE_OPERAND (cond
, 1)))
1257 tree stmt
= (TREE_CODE (cond
) == EQ_EXPR
1258 ? then_stmt
: else_stmt
);
1259 tree
*location
= (TREE_CODE (cond
) == EQ_EXPR
1260 ? &COND_EXPR_THEN (*stmt_p
)
1261 : &COND_EXPR_ELSE (*stmt_p
));
1264 && TREE_CODE (stmt
) == MODIFY_EXPR
1265 && TREE_OPERAND (stmt
, 0) == TREE_OPERAND (cond
, 0)
1266 && TREE_OPERAND (stmt
, 1) == TREE_OPERAND (cond
, 1))
1267 *location
= alloc_stmt_list ();
1271 /* Protect GOTOs in the arm of COND_EXPRs from being removed. They
1272 would be re-introduced during lowering. */
1273 data
->last_goto
= NULL
;
1278 remove_useless_stmts_tf (tree
*stmt_p
, struct rus_data
*data
)
1280 bool save_may_branch
, save_may_throw
;
1281 bool this_may_branch
, this_may_throw
;
1283 /* Collect may_branch and may_throw information for the body only. */
1284 save_may_branch
= data
->may_branch
;
1285 save_may_throw
= data
->may_throw
;
1286 data
->may_branch
= false;
1287 data
->may_throw
= false;
1288 data
->last_goto
= NULL
;
1290 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p
, 0), data
);
1292 this_may_branch
= data
->may_branch
;
1293 this_may_throw
= data
->may_throw
;
1294 data
->may_branch
|= save_may_branch
;
1295 data
->may_throw
|= save_may_throw
;
1296 data
->last_goto
= NULL
;
1298 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p
, 1), data
);
1300 /* If the body is empty, then we can emit the FINALLY block without
1301 the enclosing TRY_FINALLY_EXPR. */
1302 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p
, 0)))
1304 *stmt_p
= TREE_OPERAND (*stmt_p
, 1);
1305 data
->repeat
= true;
1308 /* If the handler is empty, then we can emit the TRY block without
1309 the enclosing TRY_FINALLY_EXPR. */
1310 else if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p
, 1)))
1312 *stmt_p
= TREE_OPERAND (*stmt_p
, 0);
1313 data
->repeat
= true;
1316 /* If the body neither throws, nor branches, then we can safely
1317 string the TRY and FINALLY blocks together. */
1318 else if (!this_may_branch
&& !this_may_throw
)
1320 tree stmt
= *stmt_p
;
1321 *stmt_p
= TREE_OPERAND (stmt
, 0);
1322 append_to_statement_list (TREE_OPERAND (stmt
, 1), stmt_p
);
1323 data
->repeat
= true;
1329 remove_useless_stmts_tc (tree
*stmt_p
, struct rus_data
*data
)
1331 bool save_may_throw
, this_may_throw
;
1332 tree_stmt_iterator i
;
1335 /* Collect may_throw information for the body only. */
1336 save_may_throw
= data
->may_throw
;
1337 data
->may_throw
= false;
1338 data
->last_goto
= NULL
;
1340 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p
, 0), data
);
1342 this_may_throw
= data
->may_throw
;
1343 data
->may_throw
= save_may_throw
;
1345 /* If the body cannot throw, then we can drop the entire TRY_CATCH_EXPR. */
1346 if (!this_may_throw
)
1348 if (warn_notreached
)
1349 remove_useless_stmts_warn_notreached (TREE_OPERAND (*stmt_p
, 1));
1350 *stmt_p
= TREE_OPERAND (*stmt_p
, 0);
1351 data
->repeat
= true;
1355 /* Process the catch clause specially. We may be able to tell that
1356 no exceptions propagate past this point. */
1358 this_may_throw
= true;
1359 i
= tsi_start (TREE_OPERAND (*stmt_p
, 1));
1360 stmt
= tsi_stmt (i
);
1361 data
->last_goto
= NULL
;
1363 switch (TREE_CODE (stmt
))
1366 for (; !tsi_end_p (i
); tsi_next (&i
))
1368 stmt
= tsi_stmt (i
);
1369 /* If we catch all exceptions, then the body does not
1370 propagate exceptions past this point. */
1371 if (CATCH_TYPES (stmt
) == NULL
)
1372 this_may_throw
= false;
1373 data
->last_goto
= NULL
;
1374 remove_useless_stmts_1 (&CATCH_BODY (stmt
), data
);
1378 case EH_FILTER_EXPR
:
1379 if (EH_FILTER_MUST_NOT_THROW (stmt
))
1380 this_may_throw
= false;
1381 else if (EH_FILTER_TYPES (stmt
) == NULL
)
1382 this_may_throw
= false;
1383 remove_useless_stmts_1 (&EH_FILTER_FAILURE (stmt
), data
);
1387 /* Otherwise this is a cleanup. */
1388 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p
, 1), data
);
1390 /* If the cleanup is empty, then we can emit the TRY block without
1391 the enclosing TRY_CATCH_EXPR. */
1392 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p
, 1)))
1394 *stmt_p
= TREE_OPERAND (*stmt_p
, 0);
1395 data
->repeat
= true;
1399 data
->may_throw
|= this_may_throw
;
1404 remove_useless_stmts_bind (tree
*stmt_p
, struct rus_data
*data
)
1408 /* First remove anything underneath the BIND_EXPR. */
1409 remove_useless_stmts_1 (&BIND_EXPR_BODY (*stmt_p
), data
);
1411 /* If the BIND_EXPR has no variables, then we can pull everything
1412 up one level and remove the BIND_EXPR, unless this is the toplevel
1413 BIND_EXPR for the current function or an inlined function.
1415 When this situation occurs we will want to apply this
1416 optimization again. */
1417 block
= BIND_EXPR_BLOCK (*stmt_p
);
1418 if (BIND_EXPR_VARS (*stmt_p
) == NULL_TREE
1419 && *stmt_p
!= DECL_SAVED_TREE (current_function_decl
)
1421 || ! BLOCK_ABSTRACT_ORIGIN (block
)
1422 || (TREE_CODE (BLOCK_ABSTRACT_ORIGIN (block
))
1425 *stmt_p
= BIND_EXPR_BODY (*stmt_p
);
1426 data
->repeat
= true;
1432 remove_useless_stmts_goto (tree
*stmt_p
, struct rus_data
*data
)
1434 tree dest
= GOTO_DESTINATION (*stmt_p
);
1436 data
->may_branch
= true;
1437 data
->last_goto
= NULL
;
1439 /* Record the last goto expr, so that we can delete it if unnecessary. */
1440 if (TREE_CODE (dest
) == LABEL_DECL
)
1441 data
->last_goto
= stmt_p
;
1446 remove_useless_stmts_label (tree
*stmt_p
, struct rus_data
*data
)
1448 tree label
= LABEL_EXPR_LABEL (*stmt_p
);
1450 data
->has_label
= true;
1452 /* We do want to jump across non-local label receiver code. */
1453 if (DECL_NONLOCAL (label
))
1454 data
->last_goto
= NULL
;
1456 else if (data
->last_goto
&& GOTO_DESTINATION (*data
->last_goto
) == label
)
1458 *data
->last_goto
= build_empty_stmt ();
1459 data
->repeat
= true;
1462 /* ??? Add something here to delete unused labels. */
1466 /* If the function is "const" or "pure", then clear TREE_SIDE_EFFECTS on its
1467 decl. This allows us to eliminate redundant or useless
1468 calls to "const" functions.
1470 Gimplifier already does the same operation, but we may notice functions
1471 being const and pure once their calls has been gimplified, so we need
1472 to update the flag. */
1475 update_call_expr_flags (tree call
)
1477 tree decl
= get_callee_fndecl (call
);
1480 if (call_expr_flags (call
) & (ECF_CONST
| ECF_PURE
))
1481 TREE_SIDE_EFFECTS (call
) = 0;
1482 if (TREE_NOTHROW (decl
))
1483 TREE_NOTHROW (call
) = 1;
1487 /* T is CALL_EXPR. Set current_function_calls_* flags. */
1490 notice_special_calls (tree t
)
1492 int flags
= call_expr_flags (t
);
1494 if (flags
& ECF_MAY_BE_ALLOCA
)
1495 current_function_calls_alloca
= true;
1496 if (flags
& ECF_RETURNS_TWICE
)
1497 current_function_calls_setjmp
= true;
1501 /* Clear flags set by notice_special_calls. Used by dead code removal
1502 to update the flags. */
1505 clear_special_calls (void)
1507 current_function_calls_alloca
= false;
1508 current_function_calls_setjmp
= false;
1513 remove_useless_stmts_1 (tree
*tp
, struct rus_data
*data
)
1517 switch (TREE_CODE (t
))
1520 remove_useless_stmts_cond (tp
, data
);
1523 case TRY_FINALLY_EXPR
:
1524 remove_useless_stmts_tf (tp
, data
);
1527 case TRY_CATCH_EXPR
:
1528 remove_useless_stmts_tc (tp
, data
);
1532 remove_useless_stmts_bind (tp
, data
);
1536 remove_useless_stmts_goto (tp
, data
);
1540 remove_useless_stmts_label (tp
, data
);
1545 data
->last_goto
= NULL
;
1546 data
->may_branch
= true;
1551 data
->last_goto
= NULL
;
1552 notice_special_calls (t
);
1553 update_call_expr_flags (t
);
1554 if (tree_could_throw_p (t
))
1555 data
->may_throw
= true;
1559 data
->last_goto
= NULL
;
1561 if (TREE_CODE (TREE_OPERAND (t
, 1)) == CALL_EXPR
)
1563 update_call_expr_flags (TREE_OPERAND (t
, 1));
1564 notice_special_calls (TREE_OPERAND (t
, 1));
1566 if (tree_could_throw_p (t
))
1567 data
->may_throw
= true;
1570 case STATEMENT_LIST
:
1572 tree_stmt_iterator i
= tsi_start (t
);
1573 while (!tsi_end_p (i
))
1576 if (IS_EMPTY_STMT (t
))
1582 remove_useless_stmts_1 (tsi_stmt_ptr (i
), data
);
1585 if (TREE_CODE (t
) == STATEMENT_LIST
)
1587 tsi_link_before (&i
, t
, TSI_SAME_STMT
);
1597 data
->last_goto
= NULL
;
1601 data
->last_goto
= NULL
;
1607 remove_useless_stmts (void)
1609 struct rus_data data
;
1611 clear_special_calls ();
1615 memset (&data
, 0, sizeof (data
));
1616 remove_useless_stmts_1 (&DECL_SAVED_TREE (current_function_decl
), &data
);
1618 while (data
.repeat
);
1622 struct tree_opt_pass pass_remove_useless_stmts
=
1624 "useless", /* name */
1626 remove_useless_stmts
, /* execute */
1629 0, /* static_pass_number */
1631 PROP_gimple_any
, /* properties_required */
1632 0, /* properties_provided */
1633 0, /* properties_destroyed */
1634 0, /* todo_flags_start */
1635 TODO_dump_func
/* todo_flags_finish */
1639 /* Remove obviously useless statements in basic block BB. */
1642 cfg_remove_useless_stmts_bb (basic_block bb
)
1644 block_stmt_iterator bsi
;
1645 tree stmt
= NULL_TREE
;
1646 tree cond
, var
= NULL_TREE
, val
= NULL_TREE
;
1647 struct var_ann_d
*ann
;
1649 /* Check whether we come here from a condition, and if so, get the
1652 || bb
->pred
->pred_next
1653 || !(bb
->pred
->flags
& (EDGE_TRUE_VALUE
| EDGE_FALSE_VALUE
)))
1656 cond
= COND_EXPR_COND (last_stmt (bb
->pred
->src
));
1658 if (TREE_CODE (cond
) == VAR_DECL
|| TREE_CODE (cond
) == PARM_DECL
)
1661 val
= (bb
->pred
->flags
& EDGE_FALSE_VALUE
1662 ? boolean_false_node
: boolean_true_node
);
1664 else if (TREE_CODE (cond
) == TRUTH_NOT_EXPR
1665 && (TREE_CODE (TREE_OPERAND (cond
, 0)) == VAR_DECL
1666 || TREE_CODE (TREE_OPERAND (cond
, 0)) == PARM_DECL
))
1668 var
= TREE_OPERAND (cond
, 0);
1669 val
= (bb
->pred
->flags
& EDGE_FALSE_VALUE
1670 ? boolean_true_node
: boolean_false_node
);
1674 if (bb
->pred
->flags
& EDGE_FALSE_VALUE
)
1675 cond
= invert_truthvalue (cond
);
1676 if (TREE_CODE (cond
) == EQ_EXPR
1677 && (TREE_CODE (TREE_OPERAND (cond
, 0)) == VAR_DECL
1678 || TREE_CODE (TREE_OPERAND (cond
, 0)) == PARM_DECL
)
1679 && (TREE_CODE (TREE_OPERAND (cond
, 1)) == VAR_DECL
1680 || TREE_CODE (TREE_OPERAND (cond
, 1)) == PARM_DECL
1681 || TREE_CONSTANT (TREE_OPERAND (cond
, 1))))
1683 var
= TREE_OPERAND (cond
, 0);
1684 val
= TREE_OPERAND (cond
, 1);
1690 /* Only work for normal local variables. */
1691 ann
= var_ann (var
);
1694 || TREE_ADDRESSABLE (var
))
1697 if (! TREE_CONSTANT (val
))
1699 ann
= var_ann (val
);
1702 || TREE_ADDRESSABLE (val
))
1706 /* Ignore floating point variables, since comparison behaves weird for
1708 if (FLOAT_TYPE_P (TREE_TYPE (var
)))
1711 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
);)
1713 stmt
= bsi_stmt (bsi
);
1715 /* If the THEN/ELSE clause merely assigns a value to a variable/parameter
1716 which is already known to contain that value, then remove the useless
1717 THEN/ELSE clause. */
1718 if (TREE_CODE (stmt
) == MODIFY_EXPR
1719 && TREE_OPERAND (stmt
, 0) == var
1720 && operand_equal_p (val
, TREE_OPERAND (stmt
, 1), 0))
1726 /* Invalidate the var if we encounter something that could modify it. */
1727 if (TREE_CODE (stmt
) == ASM_EXPR
1728 || TREE_CODE (stmt
) == VA_ARG_EXPR
1729 || (TREE_CODE (stmt
) == MODIFY_EXPR
1730 && (TREE_OPERAND (stmt
, 0) == var
1731 || TREE_OPERAND (stmt
, 0) == val
1732 || TREE_CODE (TREE_OPERAND (stmt
, 1)) == VA_ARG_EXPR
)))
1740 /* A CFG-aware version of remove_useless_stmts. */
1743 cfg_remove_useless_stmts (void)
1747 #ifdef ENABLE_CHECKING
1748 verify_flow_info ();
1753 cfg_remove_useless_stmts_bb (bb
);
1758 /* Remove PHI nodes associated with basic block BB and all edges out of BB. */
1761 remove_phi_nodes_and_edges_for_unreachable_block (basic_block bb
)
1765 /* Since this block is no longer reachable, we can just delete all
1766 of its PHI nodes. */
1767 phi
= phi_nodes (bb
);
1770 tree next
= PHI_CHAIN (phi
);
1771 remove_phi_node (phi
, NULL_TREE
, bb
);
1775 /* Remove edges to BB's successors. */
1776 while (bb
->succ
!= NULL
)
1777 ssa_remove_edge (bb
->succ
);
1781 /* Remove statements of basic block BB. */
1784 remove_bb (basic_block bb
)
1786 block_stmt_iterator i
;
1787 location_t
*loc
= NULL
;
1791 fprintf (dump_file
, "Removing basic block %d\n", bb
->index
);
1792 if (dump_flags
& TDF_DETAILS
)
1794 dump_bb (bb
, dump_file
, 0);
1795 fprintf (dump_file
, "\n");
1799 /* Remove all the instructions in the block. */
1800 for (i
= bsi_start (bb
); !bsi_end_p (i
); bsi_remove (&i
))
1802 tree stmt
= bsi_stmt (i
);
1804 set_bb_for_stmt (stmt
, NULL
);
1806 /* Don't warn for removed gotos. Gotos are often removed due to
1807 jump threading, thus resulting in bogus warnings. Not great,
1808 since this way we lose warnings for gotos in the original
1809 program that are indeed unreachable. */
1810 if (TREE_CODE (stmt
) != GOTO_EXPR
&& EXPR_LOCUS (stmt
) && !loc
)
1811 loc
= EXPR_LOCUS (stmt
);
1814 /* If requested, give a warning that the first statement in the
1815 block is unreachable. We walk statements backwards in the
1816 loop above, so the last statement we process is the first statement
1818 if (warn_notreached
&& loc
)
1819 warning ("%Hwill never be executed", loc
);
1821 remove_phi_nodes_and_edges_for_unreachable_block (bb
);
1825 /* Examine BB to determine if it is a forwarding block (a block which only
1826 transfers control to a new destination). If BB is a forwarding block,
1827 then return the edge leading to the ultimate destination. */
1830 tree_block_forwards_to (basic_block bb
)
1832 block_stmt_iterator bsi
;
1833 bb_ann_t ann
= bb_ann (bb
);
1836 /* If this block is not forwardable, then avoid useless work. */
1837 if (! ann
->forwardable
)
1840 /* Set this block to not be forwardable. This prevents infinite loops since
1841 any block currently under examination is considered non-forwardable. */
1842 ann
->forwardable
= 0;
1844 /* No forwarding is possible if this block is a special block (ENTRY/EXIT),
1845 this block has more than one successor, this block's single successor is
1846 reached via an abnormal edge, this block has phi nodes, or this block's
1847 single successor has phi nodes. */
1848 if (bb
== EXIT_BLOCK_PTR
1849 || bb
== ENTRY_BLOCK_PTR
1851 || bb
->succ
->succ_next
1852 || bb
->succ
->dest
== EXIT_BLOCK_PTR
1853 || (bb
->succ
->flags
& EDGE_ABNORMAL
) != 0
1855 || phi_nodes (bb
->succ
->dest
))
1858 /* Walk past any labels at the start of this block. */
1859 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
1861 stmt
= bsi_stmt (bsi
);
1862 if (TREE_CODE (stmt
) != LABEL_EXPR
)
1866 /* If we reached the end of this block we may be able to optimize this
1868 if (bsi_end_p (bsi
))
1872 /* Recursive call to pick up chains of forwarding blocks. */
1873 dest
= tree_block_forwards_to (bb
->succ
->dest
);
1875 /* If none found, we forward to bb->succ at minimum. */
1879 ann
->forwardable
= 1;
1883 /* No forwarding possible. */
1888 /* Try to remove superfluous control structures. */
1891 cleanup_control_flow (void)
1894 block_stmt_iterator bsi
;
1895 bool retval
= false;
1900 bsi
= bsi_last (bb
);
1902 if (bsi_end_p (bsi
))
1905 stmt
= bsi_stmt (bsi
);
1906 if (TREE_CODE (stmt
) == COND_EXPR
1907 || TREE_CODE (stmt
) == SWITCH_EXPR
)
1908 retval
|= cleanup_control_expr_graph (bb
, bsi
);
1914 /* Disconnect an unreachable block in the control expression starting
1918 cleanup_control_expr_graph (basic_block bb
, block_stmt_iterator bsi
)
1921 bool retval
= false;
1922 tree expr
= bsi_stmt (bsi
), val
;
1924 if (bb
->succ
->succ_next
)
1928 switch (TREE_CODE (expr
))
1931 val
= COND_EXPR_COND (expr
);
1935 val
= SWITCH_COND (expr
);
1936 if (TREE_CODE (val
) != INTEGER_CST
)
1944 taken_edge
= find_taken_edge (bb
, val
);
1948 /* Remove all the edges except the one that is always executed. */
1949 for (e
= bb
->succ
; e
; e
= next
)
1951 next
= e
->succ_next
;
1952 if (e
!= taken_edge
)
1954 taken_edge
->probability
+= e
->probability
;
1955 taken_edge
->count
+= e
->count
;
1956 ssa_remove_edge (e
);
1960 if (taken_edge
->probability
> REG_BR_PROB_BASE
)
1961 taken_edge
->probability
= REG_BR_PROB_BASE
;
1964 taken_edge
= bb
->succ
;
1967 taken_edge
->flags
= EDGE_FALLTHRU
;
1969 /* We removed some paths from the cfg. */
1970 if (dom_computed
[CDI_DOMINATORS
] >= DOM_CONS_OK
)
1971 dom_computed
[CDI_DOMINATORS
] = DOM_CONS_OK
;
1977 /* Given a control block BB and a constant value VAL, return the edge that
1978 will be taken out of the block. If VAL does not match a unique edge,
1979 NULL is returned. */
1982 find_taken_edge (basic_block bb
, tree val
)
1986 stmt
= last_stmt (bb
);
1988 #if defined ENABLE_CHECKING
1989 if (stmt
== NULL_TREE
|| !is_ctrl_stmt (stmt
))
1993 /* If VAL is not a constant, we can't determine which edge might
1995 if (val
== NULL
|| !really_constant_p (val
))
1998 if (TREE_CODE (stmt
) == COND_EXPR
)
1999 return find_taken_edge_cond_expr (bb
, val
);
2001 if (TREE_CODE (stmt
) == SWITCH_EXPR
)
2002 return find_taken_edge_switch_expr (bb
, val
);
2008 /* Given a constant value VAL and the entry block BB to a COND_EXPR
2009 statement, determine which of the two edges will be taken out of the
2010 block. Return NULL if either edge may be taken. */
2013 find_taken_edge_cond_expr (basic_block bb
, tree val
)
2015 edge true_edge
, false_edge
;
2017 extract_true_false_edges_from_block (bb
, &true_edge
, &false_edge
);
2019 /* If both edges of the branch lead to the same basic block, it doesn't
2020 matter which edge is taken. */
2021 if (true_edge
->dest
== false_edge
->dest
)
2024 /* Otherwise, try to determine which branch of the if() will be taken.
2025 If VAL is a constant but it can't be reduced to a 0 or a 1, then
2026 we don't really know which edge will be taken at runtime. This
2027 may happen when comparing addresses (e.g., if (&var1 == 4)). */
2028 if (integer_nonzerop (val
))
2030 else if (integer_zerop (val
))
2037 /* Given a constant value VAL and the entry block BB to a SWITCH_EXPR
2038 statement, determine which edge will be taken out of the block. Return
2039 NULL if any edge may be taken. */
2042 find_taken_edge_switch_expr (basic_block bb
, tree val
)
2044 tree switch_expr
, taken_case
;
2045 basic_block dest_bb
;
2048 if (TREE_CODE (val
) != INTEGER_CST
)
2051 switch_expr
= last_stmt (bb
);
2052 taken_case
= find_case_label_for_value (switch_expr
, val
);
2053 dest_bb
= label_to_block (CASE_LABEL (taken_case
));
2055 e
= find_edge (bb
, dest_bb
);
2062 /* Return the CASE_LABEL_EXPR that SWITCH_EXPR will take for VAL.
2063 We can make optimal use here of the fact that the case labels are
2064 sorted: We can do a binary search for a case matching VAL. */
2067 find_case_label_for_value (tree switch_expr
, tree val
)
2069 tree vec
= SWITCH_LABELS (switch_expr
);
2070 size_t low
, high
, n
= TREE_VEC_LENGTH (vec
);
2071 tree default_case
= TREE_VEC_ELT (vec
, n
- 1);
2073 for (low
= -1, high
= n
- 1; high
- low
> 1; )
2075 size_t i
= (high
+ low
) / 2;
2076 tree t
= TREE_VEC_ELT (vec
, i
);
2079 /* Cache the result of comparing CASE_LOW and val. */
2080 cmp
= tree_int_cst_compare (CASE_LOW (t
), val
);
2087 if (CASE_HIGH (t
) == NULL
)
2089 /* A singe-valued case label. */
2095 /* A case range. We can only handle integer ranges. */
2096 if (cmp
<= 0 && tree_int_cst_compare (CASE_HIGH (t
), val
) >= 0)
2101 return default_case
;
2105 /* If all the PHI nodes in DEST have alternatives for E1 and E2 and
2106 those alternatives are equal in each of the PHI nodes, then return
2107 true, else return false. */
2110 phi_alternatives_equal (basic_block dest
, edge e1
, edge e2
)
2112 tree phi
, val1
, val2
;
2115 for (phi
= phi_nodes (dest
); phi
; phi
= PHI_CHAIN (phi
))
2117 n1
= phi_arg_from_edge (phi
, e1
);
2118 n2
= phi_arg_from_edge (phi
, e2
);
2120 #ifdef ENABLE_CHECKING
2121 if (n1
< 0 || n2
< 0)
2125 val1
= PHI_ARG_DEF (phi
, n1
);
2126 val2
= PHI_ARG_DEF (phi
, n2
);
2128 if (!operand_equal_p (val1
, val2
, 0))
2136 /* Computing the Dominance Frontier:
2138 As described in Morgan, section 3.5, this may be done simply by
2139 walking the dominator tree bottom-up, computing the frontier for
2140 the children before the parent. When considering a block B,
2141 there are two cases:
2143 (1) A flow graph edge leaving B that does not lead to a child
2144 of B in the dominator tree must be a block that is either equal
2145 to B or not dominated by B. Such blocks belong in the frontier
2148 (2) Consider a block X in the frontier of one of the children C
2149 of B. If X is not equal to B and is not dominated by B, it
2150 is in the frontier of B. */
2153 compute_dominance_frontiers_1 (bitmap
*frontiers
, basic_block bb
, sbitmap done
)
2158 SET_BIT (done
, bb
->index
);
2160 /* Do the frontier of the children first. Not all children in the
2161 dominator tree (blocks dominated by this one) are children in the
2162 CFG, so check all blocks. */
2163 for (c
= first_dom_son (CDI_DOMINATORS
, bb
);
2165 c
= next_dom_son (CDI_DOMINATORS
, c
))
2167 if (! TEST_BIT (done
, c
->index
))
2168 compute_dominance_frontiers_1 (frontiers
, c
, done
);
2171 /* Find blocks conforming to rule (1) above. */
2172 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
2174 if (e
->dest
== EXIT_BLOCK_PTR
)
2176 if (get_immediate_dominator (CDI_DOMINATORS
, e
->dest
) != bb
)
2177 bitmap_set_bit (frontiers
[bb
->index
], e
->dest
->index
);
2180 /* Find blocks conforming to rule (2). */
2181 for (c
= first_dom_son (CDI_DOMINATORS
, bb
);
2183 c
= next_dom_son (CDI_DOMINATORS
, c
))
2187 EXECUTE_IF_SET_IN_BITMAP (frontiers
[c
->index
], 0, x
,
2189 if (get_immediate_dominator (CDI_DOMINATORS
, BASIC_BLOCK (x
)) != bb
)
2190 bitmap_set_bit (frontiers
[bb
->index
], x
);
2197 compute_dominance_frontiers (bitmap
*frontiers
)
2199 sbitmap done
= sbitmap_alloc (last_basic_block
);
2201 timevar_push (TV_DOM_FRONTIERS
);
2203 sbitmap_zero (done
);
2205 compute_dominance_frontiers_1 (frontiers
, ENTRY_BLOCK_PTR
->succ
->dest
, done
);
2207 sbitmap_free (done
);
2209 timevar_pop (TV_DOM_FRONTIERS
);
2214 /*---------------------------------------------------------------------------
2216 ---------------------------------------------------------------------------*/
2218 /* Dump tree-specific information of block BB to file OUTF. */
2221 tree_dump_bb (basic_block bb
, FILE *outf
, int indent
)
2223 dump_generic_bb (outf
, bb
, indent
, TDF_VOPS
);
2227 /* Dump a basic block on stderr. */
2230 debug_tree_bb (basic_block bb
)
2232 dump_bb (bb
, stderr
, 0);
2236 /* Dump basic block with index N on stderr. */
2239 debug_tree_bb_n (int n
)
2241 debug_tree_bb (BASIC_BLOCK (n
));
2242 return BASIC_BLOCK (n
);
2246 /* Dump the CFG on stderr.
2248 FLAGS are the same used by the tree dumping functions
2249 (see TDF_* in tree.h). */
2252 debug_tree_cfg (int flags
)
2254 dump_tree_cfg (stderr
, flags
);
2258 /* Dump the program showing basic block boundaries on the given FILE.
2260 FLAGS are the same used by the tree dumping functions (see TDF_* in
2264 dump_tree_cfg (FILE *file
, int flags
)
2266 if (flags
& TDF_DETAILS
)
2268 const char *funcname
2269 = lang_hooks
.decl_printable_name (current_function_decl
, 2);
2272 fprintf (file
, ";; Function %s\n\n", funcname
);
2273 fprintf (file
, ";; \n%d basic blocks, %d edges, last basic block %d.\n\n",
2274 n_basic_blocks
, n_edges
, last_basic_block
);
2276 brief_dump_cfg (file
);
2277 fprintf (file
, "\n");
2280 if (flags
& TDF_STATS
)
2281 dump_cfg_stats (file
);
2283 dump_function_to_file (current_function_decl
, file
, flags
| TDF_BLOCKS
);
2287 /* Dump CFG statistics on FILE. */
2290 dump_cfg_stats (FILE *file
)
2292 static long max_num_merged_labels
= 0;
2293 unsigned long size
, total
= 0;
2296 const char * const fmt_str
= "%-30s%-13s%12s\n";
2297 const char * const fmt_str_1
= "%-30s%13lu%11lu%c\n";
2298 const char * const fmt_str_3
= "%-43s%11lu%c\n";
2299 const char *funcname
2300 = lang_hooks
.decl_printable_name (current_function_decl
, 2);
2303 fprintf (file
, "\nCFG Statistics for %s\n\n", funcname
);
2305 fprintf (file
, "---------------------------------------------------------\n");
2306 fprintf (file
, fmt_str
, "", " Number of ", "Memory");
2307 fprintf (file
, fmt_str
, "", " instances ", "used ");
2308 fprintf (file
, "---------------------------------------------------------\n");
2310 size
= n_basic_blocks
* sizeof (struct basic_block_def
);
2312 fprintf (file
, fmt_str_1
, "Basic blocks", n_basic_blocks
, SCALE (size
),
2319 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
2322 size
= n_edges
* sizeof (struct edge_def
);
2324 fprintf (file
, fmt_str_1
, "Edges", n_edges
, SCALE (size
), LABEL (size
));
2326 size
= n_basic_blocks
* sizeof (struct bb_ann_d
);
2328 fprintf (file
, fmt_str_1
, "Basic block annotations", n_basic_blocks
,
2329 SCALE (size
), LABEL (size
));
2331 fprintf (file
, "---------------------------------------------------------\n");
2332 fprintf (file
, fmt_str_3
, "Total memory used by CFG data", SCALE (total
),
2334 fprintf (file
, "---------------------------------------------------------\n");
2335 fprintf (file
, "\n");
2337 if (cfg_stats
.num_merged_labels
> max_num_merged_labels
)
2338 max_num_merged_labels
= cfg_stats
.num_merged_labels
;
2340 fprintf (file
, "Coalesced label blocks: %ld (Max so far: %ld)\n",
2341 cfg_stats
.num_merged_labels
, max_num_merged_labels
);
2343 fprintf (file
, "\n");
2347 /* Dump CFG statistics on stderr. Keep extern so that it's always
2348 linked in the final executable. */
2351 debug_cfg_stats (void)
2353 dump_cfg_stats (stderr
);
2357 /* Dump the flowgraph to a .vcg FILE. */
2360 tree_cfg2vcg (FILE *file
)
2364 const char *funcname
2365 = lang_hooks
.decl_printable_name (current_function_decl
, 2);
2367 /* Write the file header. */
2368 fprintf (file
, "graph: { title: \"%s\"\n", funcname
);
2369 fprintf (file
, "node: { title: \"ENTRY\" label: \"ENTRY\" }\n");
2370 fprintf (file
, "node: { title: \"EXIT\" label: \"EXIT\" }\n");
2372 /* Write blocks and edges. */
2373 for (e
= ENTRY_BLOCK_PTR
->succ
; e
; e
= e
->succ_next
)
2375 fprintf (file
, "edge: { sourcename: \"ENTRY\" targetname: \"%d\"",
2378 if (e
->flags
& EDGE_FAKE
)
2379 fprintf (file
, " linestyle: dotted priority: 10");
2381 fprintf (file
, " linestyle: solid priority: 100");
2383 fprintf (file
, " }\n");
2389 enum tree_code head_code
, end_code
;
2390 const char *head_name
, *end_name
;
2393 tree first
= first_stmt (bb
);
2394 tree last
= last_stmt (bb
);
2398 head_code
= TREE_CODE (first
);
2399 head_name
= tree_code_name
[head_code
];
2400 head_line
= get_lineno (first
);
2403 head_name
= "no-statement";
2407 end_code
= TREE_CODE (last
);
2408 end_name
= tree_code_name
[end_code
];
2409 end_line
= get_lineno (last
);
2412 end_name
= "no-statement";
2414 fprintf (file
, "node: { title: \"%d\" label: \"#%d\\n%s (%d)\\n%s (%d)\"}\n",
2415 bb
->index
, bb
->index
, head_name
, head_line
, end_name
,
2418 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
2420 if (e
->dest
== EXIT_BLOCK_PTR
)
2421 fprintf (file
, "edge: { sourcename: \"%d\" targetname: \"EXIT\"", bb
->index
);
2423 fprintf (file
, "edge: { sourcename: \"%d\" targetname: \"%d\"", bb
->index
, e
->dest
->index
);
2425 if (e
->flags
& EDGE_FAKE
)
2426 fprintf (file
, " priority: 10 linestyle: dotted");
2428 fprintf (file
, " priority: 100 linestyle: solid");
2430 fprintf (file
, " }\n");
2433 if (bb
->next_bb
!= EXIT_BLOCK_PTR
)
2437 fputs ("}\n\n", file
);
2442 /*---------------------------------------------------------------------------
2443 Miscellaneous helpers
2444 ---------------------------------------------------------------------------*/
2446 /* Return true if T represents a stmt that always transfers control. */
2449 is_ctrl_stmt (tree t
)
2451 return (TREE_CODE (t
) == COND_EXPR
2452 || TREE_CODE (t
) == SWITCH_EXPR
2453 || TREE_CODE (t
) == GOTO_EXPR
2454 || TREE_CODE (t
) == RETURN_EXPR
2455 || TREE_CODE (t
) == RESX_EXPR
);
2459 /* Return true if T is a statement that may alter the flow of control
2460 (e.g., a call to a non-returning function). */
2463 is_ctrl_altering_stmt (tree t
)
2467 #if defined ENABLE_CHECKING
2472 switch (TREE_CODE (t
))
2475 /* A MODIFY_EXPR with a rhs of a call has the characteristics
2477 call
= TREE_OPERAND (t
, 1);
2478 if (TREE_CODE (call
) != CALL_EXPR
)
2483 /* A non-pure/const CALL_EXPR alters flow control if the current
2484 function has nonlocal labels. */
2485 if (TREE_SIDE_EFFECTS (t
)
2486 && current_function_has_nonlocal_label
)
2489 /* A CALL_EXPR also alters control flow if it does not return. */
2490 if (call_expr_flags (call
) & (ECF_NORETURN
| ECF_LONGJMP
))
2498 /* If a statement can throw, it alters control flow. */
2499 return tree_can_throw_internal (t
);
2503 /* Return true if T is a computed goto. */
2506 computed_goto_p (tree t
)
2508 return (TREE_CODE (t
) == GOTO_EXPR
2509 && TREE_CODE (GOTO_DESTINATION (t
)) != LABEL_DECL
);
2513 /* Checks whether EXPR is a simple local goto. */
2516 simple_goto_p (tree expr
)
2518 return (TREE_CODE (expr
) == GOTO_EXPR
2519 && TREE_CODE (GOTO_DESTINATION (expr
)) == LABEL_DECL
2520 && (decl_function_context (GOTO_DESTINATION (expr
))
2521 == current_function_decl
));
2525 /* Return true if T should start a new basic block. PREV_T is the
2526 statement preceding T. It is used when T is a label or a case label.
2527 Labels should only start a new basic block if their previous statement
2528 wasn't a label. Otherwise, sequence of labels would generate
2529 unnecessary basic blocks that only contain a single label. */
2532 stmt_starts_bb_p (tree t
, tree prev_t
)
2534 enum tree_code code
;
2539 /* LABEL_EXPRs start a new basic block only if the preceding
2540 statement wasn't a label of the same type. This prevents the
2541 creation of consecutive blocks that have nothing but a single
2543 code
= TREE_CODE (t
);
2544 if (code
== LABEL_EXPR
)
2546 /* Nonlocal and computed GOTO targets always start a new block. */
2547 if (code
== LABEL_EXPR
2548 && (DECL_NONLOCAL (LABEL_EXPR_LABEL (t
))
2549 || FORCED_LABEL (LABEL_EXPR_LABEL (t
))))
2552 if (prev_t
&& TREE_CODE (prev_t
) == code
)
2554 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (prev_t
)))
2557 cfg_stats
.num_merged_labels
++;
2568 /* Return true if T should end a basic block. */
2571 stmt_ends_bb_p (tree t
)
2573 return is_ctrl_stmt (t
) || is_ctrl_altering_stmt (t
);
2577 /* Add gotos that used to be represented implicitly in the CFG. */
2580 disband_implicit_edges (void)
2583 block_stmt_iterator last
;
2585 tree stmt
, label
, forward
;
2589 last
= bsi_last (bb
);
2590 stmt
= last_stmt (bb
);
2592 if (stmt
&& TREE_CODE (stmt
) == COND_EXPR
)
2594 /* Remove superfluous gotos from COND_EXPR branches. Moved
2595 from cfg_remove_useless_stmts here since it violates the
2596 invariants for tree--cfg correspondence and thus fits better
2597 here where we do it anyway. */
2598 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
2600 if (e
->dest
!= bb
->next_bb
)
2603 if (e
->flags
& EDGE_TRUE_VALUE
)
2604 COND_EXPR_THEN (stmt
) = build_empty_stmt ();
2605 else if (e
->flags
& EDGE_FALSE_VALUE
)
2606 COND_EXPR_ELSE (stmt
) = build_empty_stmt ();
2609 e
->flags
|= EDGE_FALLTHRU
;
2615 if (stmt
&& TREE_CODE (stmt
) == RETURN_EXPR
)
2617 /* Remove the RETURN_EXPR if we may fall though to the exit
2620 || bb
->succ
->succ_next
2621 || bb
->succ
->dest
!= EXIT_BLOCK_PTR
)
2624 if (bb
->next_bb
== EXIT_BLOCK_PTR
2625 && !TREE_OPERAND (stmt
, 0))
2628 bb
->succ
->flags
|= EDGE_FALLTHRU
;
2633 /* There can be no fallthru edge if the last statement is a control
2635 if (stmt
&& is_ctrl_stmt (stmt
))
2638 /* Find a fallthru edge and emit the goto if necessary. */
2639 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
2640 if (e
->flags
& EDGE_FALLTHRU
)
2643 if (!e
|| e
->dest
== bb
->next_bb
)
2646 if (e
->dest
== EXIT_BLOCK_PTR
)
2649 label
= tree_block_label (e
->dest
);
2651 /* If this is a goto to a goto, jump to the final destination.
2652 Handles unfactoring of the computed jumps.
2653 ??? Why bother putting this back together when rtl is just
2654 about to take it apart again? */
2655 forward
= last_and_only_stmt (e
->dest
);
2657 && TREE_CODE (forward
) == GOTO_EXPR
)
2658 label
= GOTO_DESTINATION (forward
);
2660 stmt
= build1 (GOTO_EXPR
, void_type_node
, label
);
2661 SET_EXPR_LOCUS (stmt
, e
->goto_locus
);
2662 bsi_insert_after (&last
, stmt
, BSI_NEW_STMT
);
2663 e
->flags
&= ~EDGE_FALLTHRU
;
2668 /* Remove all the blocks and edges that make up the flowgraph. */
2671 delete_tree_cfg (void)
2673 if (n_basic_blocks
> 0)
2674 free_blocks_annotations ();
2676 free_basic_block_vars ();
2677 basic_block_info
= NULL
;
2678 label_to_block_map
= NULL
;
2683 /* Return the first statement in basic block BB. */
2686 first_stmt (basic_block bb
)
2688 block_stmt_iterator i
= bsi_start (bb
);
2689 return !bsi_end_p (i
) ? bsi_stmt (i
) : NULL_TREE
;
2693 /* Return the last statement in basic block BB. */
2696 last_stmt (basic_block bb
)
2698 block_stmt_iterator b
= bsi_last (bb
);
2699 return !bsi_end_p (b
) ? bsi_stmt (b
) : NULL_TREE
;
2703 /* Return a pointer to the last statement in block BB. */
2706 last_stmt_ptr (basic_block bb
)
2708 block_stmt_iterator last
= bsi_last (bb
);
2709 return !bsi_end_p (last
) ? bsi_stmt_ptr (last
) : NULL
;
2713 /* Return the last statement of an otherwise empty block. Return NULL
2714 if the block is totally empty, or if it contains more than one
2718 last_and_only_stmt (basic_block bb
)
2720 block_stmt_iterator i
= bsi_last (bb
);
2726 last
= bsi_stmt (i
);
2731 /* Empty statements should no longer appear in the instruction stream.
2732 Everything that might have appeared before should be deleted by
2733 remove_useless_stmts, and the optimizers should just bsi_remove
2734 instead of smashing with build_empty_stmt.
2736 Thus the only thing that should appear here in a block containing
2737 one executable statement is a label. */
2738 prev
= bsi_stmt (i
);
2739 if (TREE_CODE (prev
) == LABEL_EXPR
)
2746 /* Mark BB as the basic block holding statement T. */
2749 set_bb_for_stmt (tree t
, basic_block bb
)
2751 if (TREE_CODE (t
) == STATEMENT_LIST
)
2753 tree_stmt_iterator i
;
2754 for (i
= tsi_start (t
); !tsi_end_p (i
); tsi_next (&i
))
2755 set_bb_for_stmt (tsi_stmt (i
), bb
);
2759 stmt_ann_t ann
= get_stmt_ann (t
);
2762 /* If the statement is a label, add the label to block-to-labels map
2763 so that we can speed up edge creation for GOTO_EXPRs. */
2764 if (TREE_CODE (t
) == LABEL_EXPR
)
2768 t
= LABEL_EXPR_LABEL (t
);
2769 uid
= LABEL_DECL_UID (t
);
2772 LABEL_DECL_UID (t
) = uid
= cfun
->last_label_uid
++;
2773 if (VARRAY_SIZE (label_to_block_map
) <= (unsigned) uid
)
2774 VARRAY_GROW (label_to_block_map
, 3 * uid
/ 2);
2778 #ifdef ENABLE_CHECKING
2779 /* We're moving an existing label. Make sure that we've
2780 removed it from the old block. */
2781 if (bb
&& VARRAY_BB (label_to_block_map
, uid
))
2785 VARRAY_BB (label_to_block_map
, uid
) = bb
;
2791 /* Insert statement (or statement list) T before the statement
2792 pointed-to by iterator I. M specifies how to update iterator I
2793 after insertion (see enum bsi_iterator_update). */
2796 bsi_insert_before (block_stmt_iterator
*i
, tree t
, enum bsi_iterator_update m
)
2798 set_bb_for_stmt (t
, i
->bb
);
2800 tsi_link_before (&i
->tsi
, t
, m
);
2804 /* Insert statement (or statement list) T after the statement
2805 pointed-to by iterator I. M specifies how to update iterator I
2806 after insertion (see enum bsi_iterator_update). */
2809 bsi_insert_after (block_stmt_iterator
*i
, tree t
, enum bsi_iterator_update m
)
2811 set_bb_for_stmt (t
, i
->bb
);
2813 tsi_link_after (&i
->tsi
, t
, m
);
2817 /* Remove the statement pointed to by iterator I. The iterator is updated
2818 to the next statement. */
2821 bsi_remove (block_stmt_iterator
*i
)
2823 tree t
= bsi_stmt (*i
);
2824 set_bb_for_stmt (t
, NULL
);
2826 tsi_delink (&i
->tsi
);
2830 /* Move the statement at FROM so it comes right after the statement at TO. */
2833 bsi_move_after (block_stmt_iterator
*from
, block_stmt_iterator
*to
)
2835 tree stmt
= bsi_stmt (*from
);
2837 bsi_insert_after (to
, stmt
, BSI_SAME_STMT
);
2841 /* Move the statement at FROM so it comes right before the statement at TO. */
2844 bsi_move_before (block_stmt_iterator
*from
, block_stmt_iterator
*to
)
2846 tree stmt
= bsi_stmt (*from
);
2848 bsi_insert_before (to
, stmt
, BSI_SAME_STMT
);
2852 /* Move the statement at FROM to the end of basic block BB. */
2855 bsi_move_to_bb_end (block_stmt_iterator
*from
, basic_block bb
)
2857 block_stmt_iterator last
= bsi_last (bb
);
2859 /* Have to check bsi_end_p because it could be an empty block. */
2860 if (!bsi_end_p (last
) && is_ctrl_stmt (bsi_stmt (last
)))
2861 bsi_move_before (from
, &last
);
2863 bsi_move_after (from
, &last
);
2867 /* Replace the contents of the statement pointed to by iterator BSI
2868 with STMT. If PRESERVE_EH_INFO is true, the exception handling
2869 information of the original statement is preserved. */
2872 bsi_replace (const block_stmt_iterator
*bsi
, tree stmt
, bool preserve_eh_info
)
2875 tree orig_stmt
= bsi_stmt (*bsi
);
2877 SET_EXPR_LOCUS (stmt
, EXPR_LOCUS (orig_stmt
));
2878 set_bb_for_stmt (stmt
, bsi
->bb
);
2880 /* Preserve EH region information from the original statement, if
2881 requested by the caller. */
2882 if (preserve_eh_info
)
2884 eh_region
= lookup_stmt_eh_region (orig_stmt
);
2886 add_stmt_to_eh_region (stmt
, eh_region
);
2889 *bsi_stmt_ptr (*bsi
) = stmt
;
2894 /* Insert the statement pointed-to by BSI into edge E. Every attempt
2895 is made to place the statement in an existing basic block, but
2896 sometimes that isn't possible. When it isn't possible, the edge is
2897 split and the statement is added to the new block.
2899 In all cases, the returned *BSI points to the correct location. The
2900 return value is true if insertion should be done after the location,
2901 or false if it should be done before the location. */
2904 tree_find_edge_insert_loc (edge e
, block_stmt_iterator
*bsi
)
2906 basic_block dest
, src
;
2912 /* If the destination has one predecessor which has no PHI nodes,
2913 insert there. Except for the exit block.
2915 The requirement for no PHI nodes could be relaxed. Basically we
2916 would have to examine the PHIs to prove that none of them used
2917 the value set by the statement we want to insert on E. That
2918 hardly seems worth the effort. */
2919 if (dest
->pred
->pred_next
== NULL
2920 && ! phi_nodes (dest
)
2921 && dest
!= EXIT_BLOCK_PTR
)
2923 *bsi
= bsi_start (dest
);
2924 if (bsi_end_p (*bsi
))
2927 /* Make sure we insert after any leading labels. */
2928 tmp
= bsi_stmt (*bsi
);
2929 while (TREE_CODE (tmp
) == LABEL_EXPR
)
2932 if (bsi_end_p (*bsi
))
2934 tmp
= bsi_stmt (*bsi
);
2937 if (bsi_end_p (*bsi
))
2939 *bsi
= bsi_last (dest
);
2946 /* If the source has one successor, the edge is not abnormal and
2947 the last statement does not end a basic block, insert there.
2948 Except for the entry block. */
2950 if ((e
->flags
& EDGE_ABNORMAL
) == 0
2951 && src
->succ
->succ_next
== NULL
2952 && src
!= ENTRY_BLOCK_PTR
)
2954 *bsi
= bsi_last (src
);
2955 if (bsi_end_p (*bsi
))
2958 tmp
= bsi_stmt (*bsi
);
2959 if (!stmt_ends_bb_p (tmp
))
2962 /* Insert code just before returning the value. We may need to decompose
2963 the return in the case it contains non-trivial operand. */
2964 if (TREE_CODE (tmp
) == RETURN_EXPR
)
2966 tree op
= TREE_OPERAND (tmp
, 0);
2967 if (!is_gimple_val (op
))
2969 if (TREE_CODE (op
) != MODIFY_EXPR
)
2971 bsi_insert_before (bsi
, op
, BSI_NEW_STMT
);
2972 TREE_OPERAND (tmp
, 0) = TREE_OPERAND (op
, 0);
2979 /* Otherwise, create a new basic block, and split this edge. */
2980 dest
= split_edge (e
);
2986 /* This routine will commit all pending edge insertions, creating any new
2987 basic blocks which are necessary.
2989 If specified, NEW_BLOCKS returns a count of the number of new basic
2990 blocks which were created. */
2993 bsi_commit_edge_inserts (int *new_blocks
)
2999 blocks
= n_basic_blocks
;
3001 bsi_commit_edge_inserts_1 (ENTRY_BLOCK_PTR
->succ
);
3004 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
3005 bsi_commit_edge_inserts_1 (e
);
3008 *new_blocks
= n_basic_blocks
- blocks
;
3012 /* Commit insertions pending at edge E. */
3015 bsi_commit_edge_inserts_1 (edge e
)
3017 if (PENDING_STMT (e
))
3019 block_stmt_iterator bsi
;
3020 tree stmt
= PENDING_STMT (e
);
3022 PENDING_STMT (e
) = NULL_TREE
;
3024 if (tree_find_edge_insert_loc (e
, &bsi
))
3025 bsi_insert_after (&bsi
, stmt
, BSI_NEW_STMT
);
3027 bsi_insert_before (&bsi
, stmt
, BSI_NEW_STMT
);
3032 /* Add STMT to the pending list of edge E. No actual insertion is
3033 made until a call to bsi_commit_edge_inserts () is made. */
3036 bsi_insert_on_edge (edge e
, tree stmt
)
3038 append_to_statement_list (stmt
, &PENDING_STMT (e
));
3042 /* Specialized edge insertion for SSA-PRE. FIXME: This should
3043 probably disappear. The only reason it's here is because PRE needs
3044 the call to tree_find_edge_insert_loc(). */
3046 void pre_insert_on_edge (edge e
, tree stmt
);
3049 pre_insert_on_edge (edge e
, tree stmt
)
3051 block_stmt_iterator bsi
;
3053 if (PENDING_STMT (e
))
3056 if (tree_find_edge_insert_loc (e
, &bsi
))
3057 bsi_insert_after (&bsi
, stmt
, BSI_NEW_STMT
);
3059 bsi_insert_before (&bsi
, stmt
, BSI_NEW_STMT
);
3063 /*---------------------------------------------------------------------------
3064 Tree specific functions for CFG manipulation
3065 ---------------------------------------------------------------------------*/
3067 /* Split a (typically critical) edge EDGE_IN. Return the new block.
3068 Abort on abnormal edges. */
3071 tree_split_edge (edge edge_in
)
3073 basic_block new_bb
, after_bb
, dest
, src
;
3078 /* Abnormal edges cannot be split. */
3079 if (edge_in
->flags
& EDGE_ABNORMAL
)
3083 dest
= edge_in
->dest
;
3085 /* Place the new block in the block list. Try to keep the new block
3086 near its "logical" location. This is of most help to humans looking
3087 at debugging dumps. */
3088 for (e
= dest
->pred
; e
; e
= e
->pred_next
)
3089 if (e
->src
->next_bb
== dest
)
3092 after_bb
= dest
->prev_bb
;
3094 after_bb
= edge_in
->src
;
3096 new_bb
= create_empty_bb (after_bb
);
3097 new_edge
= make_edge (new_bb
, dest
, EDGE_FALLTHRU
);
3099 /* Find all the PHI arguments on the original edge, and change them to
3100 the new edge. Do it before redirection, so that the argument does not
3102 for (phi
= phi_nodes (dest
); phi
; phi
= PHI_CHAIN (phi
))
3104 num_elem
= PHI_NUM_ARGS (phi
);
3105 for (i
= 0; i
< num_elem
; i
++)
3106 if (PHI_ARG_EDGE (phi
, i
) == edge_in
)
3108 PHI_ARG_EDGE (phi
, i
) = new_edge
;
3113 if (!redirect_edge_and_branch (edge_in
, new_bb
))
3116 if (PENDING_STMT (edge_in
))
3123 /* Return true when BB has label LABEL in it. */
3126 has_label_p (basic_block bb
, tree label
)
3128 block_stmt_iterator bsi
;
3130 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
3132 tree stmt
= bsi_stmt (bsi
);
3134 if (TREE_CODE (stmt
) != LABEL_EXPR
)
3136 if (LABEL_EXPR_LABEL (stmt
) == label
)
3143 /* Callback for walk_tree, check that all elements with address taken are
3144 properly noticed as such. */
3147 verify_expr (tree
*tp
, int *walk_subtrees ATTRIBUTE_UNUSED
,
3148 void *data ATTRIBUTE_UNUSED
)
3155 switch (TREE_CODE (t
))
3158 if (SSA_NAME_IN_FREE_LIST (t
))
3160 error ("SSA name in freelist but still referenced");
3166 x
= TREE_OPERAND (t
, 0);
3167 if (TREE_CODE (x
) == BIT_FIELD_REF
3168 && is_gimple_reg (TREE_OPERAND (x
, 0)))
3170 error ("GIMPLE register modified with BIT_FIELD_REF");
3176 x
= TREE_OPERAND (t
, 0);
3177 while (TREE_CODE (x
) == ARRAY_REF
3178 || TREE_CODE (x
) == COMPONENT_REF
3179 || TREE_CODE (x
) == REALPART_EXPR
3180 || TREE_CODE (x
) == IMAGPART_EXPR
)
3181 x
= TREE_OPERAND (x
, 0);
3182 if (TREE_CODE (x
) != VAR_DECL
&& TREE_CODE (x
) != PARM_DECL
)
3184 if (!TREE_ADDRESSABLE (x
))
3186 error ("address taken, but ADDRESSABLE bit not set");
3192 x
= TREE_OPERAND (t
, 0);
3193 if (TREE_CODE (TREE_TYPE (x
)) != BOOLEAN_TYPE
)
3195 error ("non-boolean used in condition");
3202 case FIX_TRUNC_EXPR
:
3204 case FIX_FLOOR_EXPR
:
3205 case FIX_ROUND_EXPR
:
3210 case NON_LVALUE_EXPR
:
3211 case TRUTH_NOT_EXPR
:
3212 x
= TREE_OPERAND (t
, 0);
3213 /* We check for constants explicitly since they are not considered
3214 gimple invariants if they overflowed. */
3215 if (TREE_CODE_CLASS (TREE_CODE (x
)) != 'c'
3216 && !is_gimple_val (x
))
3218 error ("Invalid operand to unary operator");
3233 case UNORDERED_EXPR
:
3244 case TRUNC_DIV_EXPR
:
3246 case FLOOR_DIV_EXPR
:
3247 case ROUND_DIV_EXPR
:
3248 case TRUNC_MOD_EXPR
:
3250 case FLOOR_MOD_EXPR
:
3251 case ROUND_MOD_EXPR
:
3253 case EXACT_DIV_EXPR
:
3263 x
= TREE_OPERAND (t
, 0);
3264 /* We check for constants explicitly since they are not considered
3265 gimple invariants if they overflowed. */
3266 if (TREE_CODE_CLASS (TREE_CODE (x
)) != 'c'
3267 && !is_gimple_val (x
))
3269 error ("Invalid operand to binary operator");
3272 x
= TREE_OPERAND (t
, 1);
3273 /* We check for constants explicitly since they are not considered
3274 gimple invariants if they overflowed. */
3275 if (TREE_CODE_CLASS (TREE_CODE (x
)) != 'c'
3276 && !is_gimple_val (x
))
3278 error ("Invalid operand to binary operator");
3290 /* Verify STMT, return true if STMT is not in GIMPLE form.
3291 TODO: Implement type checking. */
3294 verify_stmt (tree stmt
)
3298 if (!is_gimple_stmt (stmt
))
3300 error ("Is not a valid GIMPLE statement.");
3301 debug_generic_stmt (stmt
);
3305 addr
= walk_tree (&stmt
, verify_expr
, NULL
, NULL
);
3308 debug_generic_stmt (addr
);
3316 /* Return true when the T can be shared. */
3319 tree_node_can_be_shared (tree t
)
3321 if (TYPE_P (t
) || DECL_P (t
)
3322 /* We check for constants explicitly since they are not considered
3323 gimple invariants if they overflowed. */
3324 || TREE_CODE_CLASS (TREE_CODE (t
)) == 'c'
3325 || is_gimple_min_invariant (t
)
3326 || TREE_CODE (t
) == SSA_NAME
)
3329 while ((TREE_CODE (t
) == ARRAY_REF
3330 /* We check for constants explicitly since they are not considered
3331 gimple invariants if they overflowed. */
3332 && (TREE_CODE_CLASS (TREE_CODE (TREE_OPERAND (t
, 1))) == 'c'
3333 || is_gimple_min_invariant (TREE_OPERAND (t
, 1))))
3334 || (TREE_CODE (t
) == COMPONENT_REF
3335 || TREE_CODE (t
) == REALPART_EXPR
3336 || TREE_CODE (t
) == IMAGPART_EXPR
))
3337 t
= TREE_OPERAND (t
, 0);
3346 /* Called via walk_trees. Verify tree sharing. */
3349 verify_node_sharing (tree
* tp
, int *walk_subtrees
, void *data
)
3351 htab_t htab
= (htab_t
) data
;
3354 if (tree_node_can_be_shared (*tp
))
3356 *walk_subtrees
= false;
3360 slot
= htab_find_slot (htab
, *tp
, INSERT
);
3369 /* Verify the GIMPLE statement chain. */
3375 block_stmt_iterator bsi
;
3380 timevar_push (TV_TREE_STMT_VERIFY
);
3381 htab
= htab_create (37, htab_hash_pointer
, htab_eq_pointer
, NULL
);
3388 for (phi
= phi_nodes (bb
); phi
; phi
= PHI_CHAIN (phi
))
3390 int phi_num_args
= PHI_NUM_ARGS (phi
);
3392 for (i
= 0; i
< phi_num_args
; i
++)
3394 tree t
= PHI_ARG_DEF (phi
, i
);
3397 /* Addressable variables do have SSA_NAMEs but they
3398 are not considered gimple values. */
3399 if (TREE_CODE (t
) != SSA_NAME
3400 && TREE_CODE (t
) != FUNCTION_DECL
3401 && !is_gimple_val (t
))
3403 error ("PHI def is not a GIMPLE value");
3404 debug_generic_stmt (phi
);
3405 debug_generic_stmt (t
);
3409 addr
= walk_tree (&t
, verify_expr
, NULL
, NULL
);
3412 debug_generic_stmt (addr
);
3416 addr
= walk_tree (&t
, verify_node_sharing
, htab
, NULL
);
3419 error ("Incorrect sharing of tree nodes");
3420 debug_generic_stmt (phi
);
3421 debug_generic_stmt (addr
);
3427 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
3429 tree stmt
= bsi_stmt (bsi
);
3430 err
|= verify_stmt (stmt
);
3431 addr
= walk_tree (&stmt
, verify_node_sharing
, htab
, NULL
);
3434 error ("Incorrect sharing of tree nodes");
3435 debug_generic_stmt (stmt
);
3436 debug_generic_stmt (addr
);
3443 internal_error ("verify_stmts failed.");
3446 timevar_pop (TV_TREE_STMT_VERIFY
);
3450 /* Verifies that the flow information is OK. */
3453 tree_verify_flow_info (void)
3457 block_stmt_iterator bsi
;
3461 if (ENTRY_BLOCK_PTR
->stmt_list
)
3463 error ("ENTRY_BLOCK has a statement list associated with it\n");
3467 if (EXIT_BLOCK_PTR
->stmt_list
)
3469 error ("EXIT_BLOCK has a statement list associated with it\n");
3473 for (e
= EXIT_BLOCK_PTR
->pred
; e
; e
= e
->pred_next
)
3474 if (e
->flags
& EDGE_FALLTHRU
)
3476 error ("Fallthru to exit from bb %d\n", e
->src
->index
);
3482 bool found_ctrl_stmt
= false;
3484 /* Skip labels on the start of basic block. */
3485 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
3487 if (TREE_CODE (bsi_stmt (bsi
)) != LABEL_EXPR
)
3490 if (label_to_block (LABEL_EXPR_LABEL (bsi_stmt (bsi
))) != bb
)
3492 error ("Label %s to block does not match in bb %d\n",
3493 IDENTIFIER_POINTER (DECL_NAME (bsi_stmt (bsi
))),
3498 if (decl_function_context (LABEL_EXPR_LABEL (bsi_stmt (bsi
)))
3499 != current_function_decl
)
3501 error ("Label %s has incorrect context in bb %d\n",
3502 IDENTIFIER_POINTER (DECL_NAME (bsi_stmt (bsi
))),
3508 /* Verify that body of basic block BB is free of control flow. */
3509 for (; !bsi_end_p (bsi
); bsi_next (&bsi
))
3511 tree stmt
= bsi_stmt (bsi
);
3513 if (found_ctrl_stmt
)
3515 error ("Control flow in the middle of basic block %d\n",
3520 if (stmt_ends_bb_p (stmt
))
3521 found_ctrl_stmt
= true;
3523 if (TREE_CODE (stmt
) == LABEL_EXPR
)
3525 error ("Label %s in the middle of basic block %d\n",
3526 IDENTIFIER_POINTER (DECL_NAME (stmt
)),
3531 bsi
= bsi_last (bb
);
3532 if (bsi_end_p (bsi
))
3535 stmt
= bsi_stmt (bsi
);
3537 if (is_ctrl_stmt (stmt
))
3539 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
3540 if (e
->flags
& EDGE_FALLTHRU
)
3542 error ("Fallthru edge after a control statement in bb %d \n",
3548 switch (TREE_CODE (stmt
))
3554 if (TREE_CODE (COND_EXPR_THEN (stmt
)) != GOTO_EXPR
3555 || TREE_CODE (COND_EXPR_ELSE (stmt
)) != GOTO_EXPR
)
3557 error ("Structured COND_EXPR at the end of bb %d\n", bb
->index
);
3561 extract_true_false_edges_from_block (bb
, &true_edge
, &false_edge
);
3563 if (!true_edge
|| !false_edge
3564 || !(true_edge
->flags
& EDGE_TRUE_VALUE
)
3565 || !(false_edge
->flags
& EDGE_FALSE_VALUE
)
3566 || (true_edge
->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
))
3567 || (false_edge
->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
))
3568 || bb
->succ
->succ_next
->succ_next
)
3570 error ("Wrong outgoing edge flags at end of bb %d\n",
3575 if (!has_label_p (true_edge
->dest
,
3576 GOTO_DESTINATION (COND_EXPR_THEN (stmt
))))
3578 error ("`then' label does not match edge at end of bb %d\n",
3583 if (!has_label_p (false_edge
->dest
,
3584 GOTO_DESTINATION (COND_EXPR_ELSE (stmt
))))
3586 error ("`else' label does not match edge at end of bb %d\n",
3594 if (simple_goto_p (stmt
))
3596 error ("Explicit goto at end of bb %d\n", bb
->index
);
3601 /* FIXME. We should double check that the labels in the
3602 destination blocks have their address taken. */
3603 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
3604 if ((e
->flags
& (EDGE_FALLTHRU
| EDGE_TRUE_VALUE
3605 | EDGE_FALSE_VALUE
))
3606 || !(e
->flags
& EDGE_ABNORMAL
))
3608 error ("Wrong outgoing edge flags at end of bb %d\n",
3616 if (!bb
->succ
|| bb
->succ
->succ_next
3617 || (bb
->succ
->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
3618 | EDGE_TRUE_VALUE
| EDGE_FALSE_VALUE
)))
3620 error ("Wrong outgoing edge flags at end of bb %d\n", bb
->index
);
3623 if (bb
->succ
->dest
!= EXIT_BLOCK_PTR
)
3625 error ("Return edge does not point to exit in bb %d\n",
3638 vec
= SWITCH_LABELS (stmt
);
3639 n
= TREE_VEC_LENGTH (vec
);
3641 /* Mark all the destination basic blocks. */
3642 for (i
= 0; i
< n
; ++i
)
3644 tree lab
= CASE_LABEL (TREE_VEC_ELT (vec
, i
));
3645 basic_block label_bb
= label_to_block (lab
);
3647 if (label_bb
->aux
&& label_bb
->aux
!= (void *)1)
3649 label_bb
->aux
= (void *)1;
3652 /* Verify that the case labels are sorted. */
3653 prev
= TREE_VEC_ELT (vec
, 0);
3654 for (i
= 1; i
< n
- 1; ++i
)
3656 tree c
= TREE_VEC_ELT (vec
, i
);
3659 error ("Found default case not at end of case vector");
3663 if (! tree_int_cst_lt (CASE_LOW (prev
), CASE_LOW (c
)))
3665 error ("Case labels not sorted:\n ");
3666 print_generic_expr (stderr
, prev
, 0);
3667 fprintf (stderr
," is greater than ");
3668 print_generic_expr (stderr
, c
, 0);
3669 fprintf (stderr
," but comes before it.\n");
3674 if (CASE_LOW (TREE_VEC_ELT (vec
, n
- 1)))
3676 error ("No default case found at end of case vector");
3680 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
3684 error ("Extra outgoing edge %d->%d\n",
3685 bb
->index
, e
->dest
->index
);
3688 e
->dest
->aux
= (void *)2;
3689 if ((e
->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
3690 | EDGE_TRUE_VALUE
| EDGE_FALSE_VALUE
)))
3692 error ("Wrong outgoing edge flags at end of bb %d\n",
3698 /* Check that we have all of them. */
3699 for (i
= 0; i
< n
; ++i
)
3701 tree lab
= CASE_LABEL (TREE_VEC_ELT (vec
, i
));
3702 basic_block label_bb
= label_to_block (lab
);
3704 if (label_bb
->aux
!= (void *)2)
3706 error ("Missing edge %i->%i\n",
3707 bb
->index
, label_bb
->index
);
3712 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
3713 e
->dest
->aux
= (void *)0;
3720 if (dom_computed
[CDI_DOMINATORS
] >= DOM_NO_FAST_QUERY
)
3721 verify_dominators (CDI_DOMINATORS
);
3727 /* Updates phi nodes after creating forwarder block joined
3728 by edge FALLTHRU. */
3731 tree_make_forwarder_block (edge fallthru
)
3734 basic_block dummy
, bb
;
3735 tree phi
, new_phi
, var
, prev
, next
;
3737 dummy
= fallthru
->src
;
3738 bb
= fallthru
->dest
;
3740 if (!bb
->pred
->pred_next
)
3743 /* If we redirected a branch we must create new phi nodes at the
3745 for (phi
= phi_nodes (dummy
); phi
; phi
= PHI_CHAIN (phi
))
3747 var
= PHI_RESULT (phi
);
3748 new_phi
= create_phi_node (var
, bb
);
3749 SSA_NAME_DEF_STMT (var
) = new_phi
;
3750 SET_PHI_RESULT (phi
, make_ssa_name (SSA_NAME_VAR (var
), phi
));
3751 add_phi_arg (&new_phi
, PHI_RESULT (phi
), fallthru
);
3754 /* Ensure that the PHI node chain is in the same order. */
3756 for (phi
= phi_nodes (bb
); phi
; phi
= next
)
3758 next
= PHI_CHAIN (phi
);
3759 PHI_CHAIN (phi
) = prev
;
3762 set_phi_nodes (bb
, prev
);
3764 /* Add the arguments we have stored on edges. */
3765 for (e
= bb
->pred
; e
; e
= e
->pred_next
)
3770 for (phi
= phi_nodes (bb
), var
= PENDING_STMT (e
);
3772 phi
= PHI_CHAIN (phi
), var
= TREE_CHAIN (var
))
3773 add_phi_arg (&phi
, TREE_VALUE (var
), e
);
3775 PENDING_STMT (e
) = NULL
;
3780 /* Return true if basic block BB does nothing except pass control
3781 flow to another block and that we can safely insert a label at
3782 the start of the successor block. */
3785 tree_forwarder_block_p (basic_block bb
)
3787 block_stmt_iterator bsi
;
3790 /* If we have already determined that this block is not forwardable,
3791 then no further checks are necessary. */
3792 if (! bb_ann (bb
)->forwardable
)
3795 /* BB must have a single outgoing normal edge. Otherwise it can not be
3796 a forwarder block. */
3798 || bb
->succ
->succ_next
3799 || bb
->succ
->dest
== EXIT_BLOCK_PTR
3800 || (bb
->succ
->flags
& EDGE_ABNORMAL
)
3801 || bb
== ENTRY_BLOCK_PTR
)
3803 bb_ann (bb
)->forwardable
= 0;
3807 /* Successors of the entry block are not forwarders. */
3808 for (e
= ENTRY_BLOCK_PTR
->succ
; e
; e
= e
->succ_next
)
3811 bb_ann (bb
)->forwardable
= 0;
3815 /* BB can not have any PHI nodes. This could potentially be relaxed
3816 early in compilation if we re-rewrote the variables appearing in
3817 any PHI nodes in forwarder blocks. */
3820 bb_ann (bb
)->forwardable
= 0;
3824 /* Now walk through the statements. We can ignore labels, anything else
3825 means this is not a forwarder block. */
3826 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
3828 tree stmt
= bsi_stmt (bsi
);
3830 switch (TREE_CODE (stmt
))
3833 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt
)))
3838 bb_ann (bb
)->forwardable
= 0;
3847 /* Thread jumps over empty statements.
3849 This code should _not_ thread over obviously equivalent conditions
3850 as that requires nontrivial updates to the SSA graph. */
3855 edge e
, next
, last
, old
;
3856 basic_block bb
, dest
, tmp
;
3859 bool retval
= false;
3862 bb_ann (bb
)->forwardable
= 1;
3864 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
, EXIT_BLOCK_PTR
, next_bb
)
3866 /* Don't waste time on unreachable blocks. */
3870 /* Nor on forwarders. */
3871 if (tree_forwarder_block_p (bb
))
3874 /* This block is now part of a forwarding path, mark it as not
3875 forwardable so that we can detect loops. This bit will be
3877 bb_ann (bb
)->forwardable
= 0;
3879 /* Examine each of our block's successors to see if it is
3881 for (e
= bb
->succ
; e
; e
= next
)
3883 next
= e
->succ_next
;
3885 /* If the edge is abnormal or its destination is not
3886 forwardable, then there's nothing to do. */
3887 if ((e
->flags
& EDGE_ABNORMAL
)
3888 || !tree_forwarder_block_p (e
->dest
))
3891 /* Now walk through as many forwarder block as possible to
3892 find the ultimate destination we want to thread our jump
3894 last
= e
->dest
->succ
;
3895 bb_ann (e
->dest
)->forwardable
= 0;
3896 for (dest
= e
->dest
->succ
->dest
;
3897 tree_forwarder_block_p (dest
);
3899 dest
= dest
->succ
->dest
)
3901 /* An infinite loop detected. We redirect the edge anyway, so
3902 that the loop is shrinked into single basic block. */
3903 if (!bb_ann (dest
)->forwardable
)
3906 if (dest
->succ
->dest
== EXIT_BLOCK_PTR
)
3909 bb_ann (dest
)->forwardable
= 0;
3912 /* Reset the forwardable marks to 1. */
3915 tmp
= tmp
->succ
->dest
)
3916 bb_ann (tmp
)->forwardable
= 1;
3918 if (dest
== e
->dest
)
3921 old
= find_edge (bb
, dest
);
3924 /* If there already is an edge, check whether the values
3925 in phi nodes differ. */
3926 if (!phi_alternatives_equal (dest
, last
, old
))
3928 /* The previous block is forwarder. Redirect our jump
3929 to that target instead since we know it has no PHI
3930 nodes that will need updating. */
3933 /* That might mean that no forwarding at all is possible. */
3934 if (dest
== e
->dest
)
3937 old
= find_edge (bb
, dest
);
3941 /* Perform the redirection. */
3943 e
= redirect_edge_and_branch (e
, dest
);
3945 /* TODO -- updating dominators in this case is simple. */
3946 free_dominance_info (CDI_DOMINATORS
);
3950 /* Update PHI nodes. We know that the new argument should
3951 have the same value as the argument associated with LAST.
3952 Otherwise we would have changed our target block above. */
3953 for (phi
= phi_nodes (dest
); phi
; phi
= PHI_CHAIN (phi
))
3955 arg
= phi_arg_from_edge (phi
, last
);
3958 add_phi_arg (&phi
, PHI_ARG_DEF (phi
, arg
), e
);
3963 /* Reset the forwardable bit on our block since it's no longer in
3964 a forwarding chain path. */
3965 bb_ann (bb
)->forwardable
= 1;
3972 /* Return a non-special label in the head of basic block BLOCK.
3973 Create one if it doesn't exist. */
3976 tree_block_label (basic_block bb
)
3978 block_stmt_iterator i
, s
= bsi_start (bb
);
3982 for (i
= s
; !bsi_end_p (i
); first
= false, bsi_next (&i
))
3984 stmt
= bsi_stmt (i
);
3985 if (TREE_CODE (stmt
) != LABEL_EXPR
)
3987 label
= LABEL_EXPR_LABEL (stmt
);
3988 if (!DECL_NONLOCAL (label
))
3991 bsi_move_before (&i
, &s
);
3996 label
= create_artificial_label ();
3997 stmt
= build1 (LABEL_EXPR
, void_type_node
, label
);
3998 bsi_insert_before (&s
, stmt
, BSI_NEW_STMT
);
4003 /* Attempt to perform edge redirection by replacing a possibly complex
4004 jump instruction by a goto or by removing the jump completely.
4005 This can apply only if all edges now point to the same block. The
4006 parameters and return values are equivalent to
4007 redirect_edge_and_branch. */
4010 tree_try_redirect_by_replacing_jump (edge e
, basic_block target
)
4012 basic_block src
= e
->src
;
4014 block_stmt_iterator b
;
4017 /* Verify that all targets will be TARGET. */
4018 for (tmp
= src
->succ
; tmp
; tmp
= tmp
->succ_next
)
4019 if (tmp
->dest
!= target
&& tmp
!= e
)
4028 stmt
= bsi_stmt (b
);
4030 if (TREE_CODE (stmt
) == COND_EXPR
4031 || TREE_CODE (stmt
) == SWITCH_EXPR
)
4034 e
= ssa_redirect_edge (e
, target
);
4035 e
->flags
= EDGE_FALLTHRU
;
4043 /* Redirect E to DEST. Return NULL on failure. Otherwise, return the
4044 edge representing the redirected branch. */
4047 tree_redirect_edge_and_branch (edge e
, basic_block dest
)
4049 basic_block bb
= e
->src
;
4050 block_stmt_iterator bsi
;
4054 if (e
->flags
& (EDGE_ABNORMAL_CALL
| EDGE_EH
))
4057 if (e
->src
!= ENTRY_BLOCK_PTR
4058 && (ret
= tree_try_redirect_by_replacing_jump (e
, dest
)))
4061 if (e
->dest
== dest
)
4064 label
= tree_block_label (dest
);
4066 bsi
= bsi_last (bb
);
4067 stmt
= bsi_end_p (bsi
) ? NULL
: bsi_stmt (bsi
);
4069 switch (stmt
? TREE_CODE (stmt
) : ERROR_MARK
)
4072 stmt
= (e
->flags
& EDGE_TRUE_VALUE
4073 ? COND_EXPR_THEN (stmt
)
4074 : COND_EXPR_ELSE (stmt
));
4075 GOTO_DESTINATION (stmt
) = label
;
4079 /* No non-abnormal edges should lead from a non-simple goto, and
4080 simple ones should be represented implicitly. */
4085 tree vec
= SWITCH_LABELS (stmt
);
4086 size_t i
, n
= TREE_VEC_LENGTH (vec
);
4088 for (i
= 0; i
< n
; ++i
)
4090 tree elt
= TREE_VEC_ELT (vec
, i
);
4091 if (label_to_block (CASE_LABEL (elt
)) == e
->dest
)
4092 CASE_LABEL (elt
) = label
;
4099 e
->flags
|= EDGE_FALLTHRU
;
4103 /* Otherwise it must be a fallthru edge, and we don't need to
4104 do anything besides redirecting it. */
4105 if (!(e
->flags
& EDGE_FALLTHRU
))
4110 /* Update/insert PHI nodes as necessary. */
4112 /* Now update the edges in the CFG. */
4113 e
= ssa_redirect_edge (e
, dest
);
4119 /* Simple wrapper, as we can always redirect fallthru edges. */
4122 tree_redirect_edge_and_branch_force (edge e
, basic_block dest
)
4124 e
= tree_redirect_edge_and_branch (e
, dest
);
4132 /* Splits basic block BB after statement STMT (but at least after the
4133 labels). If STMT is NULL, BB is split just after the labels. */
4136 tree_split_block (basic_block bb
, void *stmt
)
4138 block_stmt_iterator bsi
, bsi_tgt
;
4143 new_bb
= create_empty_bb (bb
);
4145 /* Redirect the outgoing edges. */
4146 new_bb
->succ
= bb
->succ
;
4148 for (e
= new_bb
->succ
; e
; e
= e
->succ_next
)
4151 if (stmt
&& TREE_CODE ((tree
) stmt
) == LABEL_EXPR
)
4154 /* Move everything from BSI to the new basic block. */
4155 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
4157 act
= bsi_stmt (bsi
);
4158 if (TREE_CODE (act
) == LABEL_EXPR
)
4171 bsi_tgt
= bsi_start (new_bb
);
4172 while (!bsi_end_p (bsi
))
4174 act
= bsi_stmt (bsi
);
4176 bsi_insert_after (&bsi_tgt
, act
, BSI_NEW_STMT
);
4183 /* Moves basic block BB after block AFTER. */
4186 tree_move_block_after (basic_block bb
, basic_block after
)
4188 if (bb
->prev_bb
== after
)
4192 link_block (bb
, after
);
4198 /* Return true if basic_block can be duplicated. */
4201 tree_can_duplicate_bb_p (basic_block bb ATTRIBUTE_UNUSED
)
4207 /* Create a duplicate of the basic block BB. NOTE: This does not
4208 preserve SSA form. */
4211 tree_duplicate_bb (basic_block bb
)
4214 block_stmt_iterator bsi
, bsi_tgt
;
4216 new_bb
= create_empty_bb (EXIT_BLOCK_PTR
->prev_bb
);
4217 bsi_tgt
= bsi_start (new_bb
);
4218 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
4220 tree stmt
= bsi_stmt (bsi
);
4222 if (TREE_CODE (stmt
) == LABEL_EXPR
)
4225 bsi_insert_after (&bsi_tgt
, unshare_expr (stmt
), BSI_NEW_STMT
);
4232 /* Dump FUNCTION_DECL FN to file FILE using FLAGS (see TDF_* in tree.h) */
4235 dump_function_to_file (tree fn
, FILE *file
, int flags
)
4237 tree arg
, vars
, var
;
4238 bool ignore_topmost_bind
= false, any_var
= false;
4242 fprintf (file
, "%s (", lang_hooks
.decl_printable_name (fn
, 2));
4244 arg
= DECL_ARGUMENTS (fn
);
4247 print_generic_expr (file
, arg
, dump_flags
);
4248 if (TREE_CHAIN (arg
))
4249 fprintf (file
, ", ");
4250 arg
= TREE_CHAIN (arg
);
4252 fprintf (file
, ")\n");
4254 if (flags
& TDF_RAW
)
4256 dump_node (fn
, TDF_SLIM
| flags
, file
);
4260 /* When GIMPLE is lowered, the variables are no longer available in
4261 BIND_EXPRs, so display them separately. */
4262 if (cfun
&& cfun
->unexpanded_var_list
)
4264 ignore_topmost_bind
= true;
4266 fprintf (file
, "{\n");
4267 for (vars
= cfun
->unexpanded_var_list
; vars
; vars
= TREE_CHAIN (vars
))
4269 var
= TREE_VALUE (vars
);
4271 print_generic_decl (file
, var
, flags
);
4272 fprintf (file
, "\n");
4278 if (basic_block_info
)
4280 /* Make a CFG based dump. */
4281 if (!ignore_topmost_bind
)
4282 fprintf (file
, "{\n");
4284 if (any_var
&& n_basic_blocks
)
4285 fprintf (file
, "\n");
4288 dump_generic_bb (file
, bb
, 2, flags
);
4290 fprintf (file
, "}\n");
4296 /* Make a tree based dump. */
4297 chain
= DECL_SAVED_TREE (fn
);
4299 if (TREE_CODE (chain
) == BIND_EXPR
)
4301 if (ignore_topmost_bind
)
4303 chain
= BIND_EXPR_BODY (chain
);
4311 if (!ignore_topmost_bind
)
4312 fprintf (file
, "{\n");
4317 fprintf (file
, "\n");
4319 print_generic_stmt_indented (file
, chain
, flags
, indent
);
4320 if (ignore_topmost_bind
)
4321 fprintf (file
, "}\n");
4324 fprintf (file
, "\n\n");
4328 /* Pretty print of the loops intermediate representation. */
4329 static void print_loop (FILE *, struct loop
*, int);
4330 static void print_pred_bbs (FILE *, edge
);
4331 static void print_succ_bbs (FILE *, edge
);
4334 /* Print the predecessors indexes of edge E on FILE. */
4337 print_pred_bbs (FILE *file
, edge e
)
4342 else if (e
->pred_next
== NULL
)
4343 fprintf (file
, "bb_%d", e
->src
->index
);
4347 fprintf (file
, "bb_%d, ", e
->src
->index
);
4348 print_pred_bbs (file
, e
->pred_next
);
4353 /* Print the successors indexes of edge E on FILE. */
4356 print_succ_bbs (FILE *file
, edge e
)
4360 else if (e
->succ_next
== NULL
)
4361 fprintf (file
, "bb_%d", e
->dest
->index
);
4364 fprintf (file
, "bb_%d, ", e
->dest
->index
);
4365 print_succ_bbs (file
, e
->succ_next
);
4370 /* Pretty print LOOP on FILE, indented INDENT spaces. */
4373 print_loop (FILE *file
, struct loop
*loop
, int indent
)
4381 s_indent
= (char *) alloca ((size_t) indent
+ 1);
4382 memset ((void *) s_indent
, ' ', (size_t) indent
);
4383 s_indent
[indent
] = '\0';
4385 /* Print the loop's header. */
4386 fprintf (file
, "%sloop_%d\n", s_indent
, loop
->num
);
4388 /* Print the loop's body. */
4389 fprintf (file
, "%s{\n", s_indent
);
4391 if (bb
->loop_father
== loop
)
4393 /* Print the basic_block's header. */
4394 fprintf (file
, "%s bb_%d (preds = {", s_indent
, bb
->index
);
4395 print_pred_bbs (file
, bb
->pred
);
4396 fprintf (file
, "}, succs = {");
4397 print_succ_bbs (file
, bb
->succ
);
4398 fprintf (file
, "})\n");
4400 /* Print the basic_block's body. */
4401 fprintf (file
, "%s {\n", s_indent
);
4402 tree_dump_bb (bb
, file
, indent
+ 4);
4403 fprintf (file
, "%s }\n", s_indent
);
4406 print_loop (file
, loop
->inner
, indent
+ 2);
4407 fprintf (file
, "%s}\n", s_indent
);
4408 print_loop (file
, loop
->next
, indent
);
4412 /* Follow a CFG edge from the entry point of the program, and on entry
4413 of a loop, pretty print the loop structure on FILE. */
4416 print_loop_ir (FILE *file
)
4420 bb
= BASIC_BLOCK (0);
4421 if (bb
&& bb
->loop_father
)
4422 print_loop (file
, bb
->loop_father
, 0);
4426 /* Debugging loops structure at tree level. */
4429 debug_loop_ir (void)
4431 print_loop_ir (stderr
);
4435 /* Return true if BB ends with a call, possibly followed by some
4436 instructions that must stay with the call. Return false,
4440 tree_block_ends_with_call_p (basic_block bb
)
4442 block_stmt_iterator bsi
= bsi_last (bb
);
4443 tree t
= tsi_stmt (bsi
.tsi
);
4445 if (TREE_CODE (t
) == RETURN_EXPR
&& TREE_OPERAND (t
, 0))
4446 t
= TREE_OPERAND (t
, 0);
4448 if (TREE_CODE (t
) == MODIFY_EXPR
)
4449 t
= TREE_OPERAND (t
, 1);
4451 return TREE_CODE (t
) == CALL_EXPR
;
4455 /* Return true if BB ends with a conditional branch. Return false,
4459 tree_block_ends_with_condjump_p (basic_block bb
)
4461 tree stmt
= tsi_stmt (bsi_last (bb
).tsi
);
4462 return (TREE_CODE (stmt
) == COND_EXPR
);
4466 /* Return true if we need to add fake edge to exit at statement T.
4467 Helper function for tree_flow_call_edges_add. */
4470 need_fake_edge_p (tree t
)
4472 if (TREE_CODE (t
) == RETURN_EXPR
&& TREE_OPERAND (t
, 0))
4473 t
= TREE_OPERAND (t
, 0);
4475 if (TREE_CODE (t
) == MODIFY_EXPR
)
4476 t
= TREE_OPERAND (t
, 1);
4478 /* NORETURN and LONGJMP calls already have an edge to exit.
4479 CONST, PURE and ALWAYS_RETURN calls do not need one.
4480 We don't currently check for CONST and PURE here, although
4481 it would be a good idea, because those attributes are
4482 figured out from the RTL in mark_constant_function, and
4483 the counter incrementation code from -fprofile-arcs
4484 leads to different results from -fbranch-probabilities. */
4485 if (TREE_CODE (t
) == CALL_EXPR
4486 && !(call_expr_flags (t
) &
4487 (ECF_NORETURN
| ECF_LONGJMP
| ECF_ALWAYS_RETURN
)))
4490 if (TREE_CODE (t
) == ASM_EXPR
4491 && (ASM_VOLATILE_P (t
) || ASM_INPUT_P (t
)))
4498 /* Add fake edges to the function exit for any non constant and non
4499 noreturn calls, volatile inline assembly in the bitmap of blocks
4500 specified by BLOCKS or to the whole CFG if BLOCKS is zero. Return
4501 the number of blocks that were split.
4503 The goal is to expose cases in which entering a basic block does
4504 not imply that all subsequent instructions must be executed. */
4507 tree_flow_call_edges_add (sbitmap blocks
)
4510 int blocks_split
= 0;
4511 int last_bb
= last_basic_block
;
4512 bool check_last_block
= false;
4514 if (n_basic_blocks
== 0)
4518 check_last_block
= true;
4520 check_last_block
= TEST_BIT (blocks
, EXIT_BLOCK_PTR
->prev_bb
->index
);
4522 /* In the last basic block, before epilogue generation, there will be
4523 a fallthru edge to EXIT. Special care is required if the last insn
4524 of the last basic block is a call because make_edge folds duplicate
4525 edges, which would result in the fallthru edge also being marked
4526 fake, which would result in the fallthru edge being removed by
4527 remove_fake_edges, which would result in an invalid CFG.
4529 Moreover, we can't elide the outgoing fake edge, since the block
4530 profiler needs to take this into account in order to solve the minimal
4531 spanning tree in the case that the call doesn't return.
4533 Handle this by adding a dummy instruction in a new last basic block. */
4534 if (check_last_block
)
4536 basic_block bb
= EXIT_BLOCK_PTR
->prev_bb
;
4537 block_stmt_iterator bsi
= bsi_last (bb
);
4539 if (!bsi_end_p (bsi
))
4542 if (need_fake_edge_p (t
))
4546 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
4547 if (e
->dest
== EXIT_BLOCK_PTR
)
4549 bsi_insert_on_edge (e
, build_empty_stmt ());
4550 bsi_commit_edge_inserts ((int *)NULL
);
4556 /* Now add fake edges to the function exit for any non constant
4557 calls since there is no way that we can determine if they will
4559 for (i
= 0; i
< last_bb
; i
++)
4561 basic_block bb
= BASIC_BLOCK (i
);
4562 block_stmt_iterator bsi
;
4563 tree stmt
, last_stmt
;
4568 if (blocks
&& !TEST_BIT (blocks
, i
))
4571 bsi
= bsi_last (bb
);
4572 if (!bsi_end_p (bsi
))
4574 last_stmt
= bsi_stmt (bsi
);
4577 stmt
= bsi_stmt (bsi
);
4578 if (need_fake_edge_p (stmt
))
4581 /* The handling above of the final block before the
4582 epilogue should be enough to verify that there is
4583 no edge to the exit block in CFG already.
4584 Calling make_edge in such case would cause us to
4585 mark that edge as fake and remove it later. */
4586 #ifdef ENABLE_CHECKING
4587 if (stmt
== last_stmt
)
4588 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
4589 if (e
->dest
== EXIT_BLOCK_PTR
)
4593 /* Note that the following may create a new basic block
4594 and renumber the existing basic blocks. */
4595 if (stmt
!= last_stmt
)
4597 e
= split_block (bb
, stmt
);
4601 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
4605 while (!bsi_end_p (bsi
));
4610 verify_flow_info ();
4612 return blocks_split
;
4616 struct cfg_hooks tree_cfg_hooks
= {
4618 tree_verify_flow_info
,
4619 tree_dump_bb
, /* dump_bb */
4620 create_bb
, /* create_basic_block */
4621 tree_redirect_edge_and_branch
,/* redirect_edge_and_branch */
4622 tree_redirect_edge_and_branch_force
,/* redirect_edge_and_branch_force */
4623 remove_bb
, /* delete_basic_block */
4624 tree_split_block
, /* split_block */
4625 tree_move_block_after
, /* move_block_after */
4626 tree_can_merge_blocks_p
, /* can_merge_blocks_p */
4627 tree_merge_blocks
, /* merge_blocks */
4628 tree_predict_edge
, /* predict_edge */
4629 tree_predicted_by_p
, /* predicted_by_p */
4630 tree_can_duplicate_bb_p
, /* can_duplicate_block_p */
4631 tree_duplicate_bb
, /* duplicate_block */
4632 tree_split_edge
, /* split_edge */
4633 tree_make_forwarder_block
, /* make_forward_block */
4634 NULL
, /* tidy_fallthru_edge */
4635 tree_block_ends_with_call_p
, /* block_ends_with_call_p */
4636 tree_block_ends_with_condjump_p
, /* block_ends_with_condjump_p */
4637 tree_flow_call_edges_add
/* flow_call_edges_add */
4641 /* Split all critical edges. */
4644 split_critical_edges (void)
4651 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
4652 if (EDGE_CRITICAL_P (e
) && !(e
->flags
& EDGE_ABNORMAL
))
4659 struct tree_opt_pass pass_split_crit_edges
=
4661 "crited", /* name */
4663 split_critical_edges
, /* execute */
4666 0, /* static_pass_number */
4667 TV_TREE_SPLIT_EDGES
, /* tv_id */
4668 PROP_cfg
, /* properties required */
4669 PROP_no_crit_edges
, /* properties_provided */
4670 0, /* properties_destroyed */
4671 0, /* todo_flags_start */
4672 TODO_dump_func
, /* todo_flags_finish */
4675 /* Emit return warnings. */
4678 execute_warn_function_return (void)
4684 if (warn_missing_noreturn
4685 && !TREE_THIS_VOLATILE (cfun
->decl
)
4686 && EXIT_BLOCK_PTR
->pred
== NULL
4687 && !lang_hooks
.function
.missing_noreturn_ok_p (cfun
->decl
))
4688 warning ("%Jfunction might be possible candidate for attribute `noreturn'",
4691 /* If we have a path to EXIT, then we do return. */
4692 if (TREE_THIS_VOLATILE (cfun
->decl
)
4693 && EXIT_BLOCK_PTR
->pred
!= NULL
)
4696 for (e
= EXIT_BLOCK_PTR
->pred
; e
; e
= e
->pred_next
)
4698 last
= last_stmt (e
->src
);
4699 if (TREE_CODE (last
) == RETURN_EXPR
4700 && (locus
= EXPR_LOCUS (last
)) != NULL
)
4704 locus
= &cfun
->function_end_locus
;
4705 warning ("%H`noreturn' function does return", locus
);
4708 /* If we see "return;" in some basic block, then we do reach the end
4709 without returning a value. */
4710 else if (warn_return_type
4711 && EXIT_BLOCK_PTR
->pred
!= NULL
4712 && !VOID_TYPE_P (TREE_TYPE (TREE_TYPE (cfun
->decl
))))
4714 for (e
= EXIT_BLOCK_PTR
->pred
; e
; e
= e
->pred_next
)
4716 tree last
= last_stmt (e
->src
);
4717 if (TREE_CODE (last
) == RETURN_EXPR
4718 && TREE_OPERAND (last
, 0) == NULL
)
4720 locus
= EXPR_LOCUS (last
);
4722 locus
= &cfun
->function_end_locus
;
4723 warning ("%Hcontrol reaches end of non-void function", locus
);
4731 /* Given a basic block B which ends with a conditional and has
4732 precisely two successors, determine which of the edges is taken if
4733 the conditional is true and which is taken if the conditional is
4734 false. Set TRUE_EDGE and FALSE_EDGE appropriately. */
4737 extract_true_false_edges_from_block (basic_block b
,
4743 if (e
->flags
& EDGE_TRUE_VALUE
)
4746 *false_edge
= e
->succ_next
;
4751 *true_edge
= e
->succ_next
;
4755 struct tree_opt_pass pass_warn_function_return
=
4759 execute_warn_function_return
, /* execute */
4762 0, /* static_pass_number */
4764 PROP_ssa
, /* properties_required */
4765 0, /* properties_provided */
4766 0, /* properties_destroyed */
4767 0, /* todo_flags_start */
4768 0 /* todo_flags_finish */
4771 #include "gt-tree-cfg.h"