1 /* Control flow functions for trees.
2 Copyright (C) 2001, 2002, 2003, 2004, 2005 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"
36 #include "langhooks.h"
37 #include "diagnostic.h"
38 #include "tree-flow.h"
40 #include "tree-dump.h"
41 #include "tree-pass.h"
45 #include "cfglayout.h"
47 #include "tree-ssa-propagate.h"
49 /* This file contains functions for building the Control Flow Graph (CFG)
50 for a function tree. */
52 /* Local declarations. */
54 /* Initial capacity for the basic block array. */
55 static const int initial_cfg_capacity
= 20;
57 /* This hash table allows us to efficiently lookup all CASE_LABEL_EXPRs
58 which use a particular edge. The CASE_LABEL_EXPRs are chained together
59 via their TREE_CHAIN field, which we clear after we're done with the
60 hash table to prevent problems with duplication of SWITCH_EXPRs.
62 Access to this list of CASE_LABEL_EXPRs allows us to efficiently
63 update the case vector in response to edge redirections.
65 Right now this table is set up and torn down at key points in the
66 compilation process. It would be nice if we could make the table
67 more persistent. The key is getting notification of changes to
68 the CFG (particularly edge removal, creation and redirection). */
70 struct edge_to_cases_elt
72 /* The edge itself. Necessary for hashing and equality tests. */
75 /* The case labels associated with this edge. We link these up via
76 their TREE_CHAIN field, then we wipe out the TREE_CHAIN fields
77 when we destroy the hash table. This prevents problems when copying
82 static htab_t edge_to_cases
;
87 long num_merged_labels
;
90 static struct cfg_stats_d cfg_stats
;
92 /* Nonzero if we found a computed goto while building basic blocks. */
93 static bool found_computed_goto
;
95 /* Basic blocks and flowgraphs. */
96 static basic_block
create_bb (void *, void *, basic_block
);
97 static void make_blocks (tree
);
98 static void factor_computed_gotos (void);
101 static void make_edges (void);
102 static void make_ctrl_stmt_edges (basic_block
);
103 static void make_exit_edges (basic_block
);
104 static void make_cond_expr_edges (basic_block
);
105 static void make_switch_expr_edges (basic_block
);
106 static void make_goto_expr_edges (basic_block
);
107 static edge
tree_redirect_edge_and_branch (edge
, basic_block
);
108 static edge
tree_try_redirect_by_replacing_jump (edge
, basic_block
);
109 static void split_critical_edges (void);
111 /* Various helpers. */
112 static inline bool stmt_starts_bb_p (tree
, tree
);
113 static int tree_verify_flow_info (void);
114 static void tree_make_forwarder_block (edge
);
115 static void tree_cfg2vcg (FILE *);
117 /* Flowgraph optimization and cleanup. */
118 static void tree_merge_blocks (basic_block
, basic_block
);
119 static bool tree_can_merge_blocks_p (basic_block
, basic_block
);
120 static void remove_bb (basic_block
);
121 static edge
find_taken_edge_computed_goto (basic_block
, tree
);
122 static edge
find_taken_edge_cond_expr (basic_block
, tree
);
123 static edge
find_taken_edge_switch_expr (basic_block
, tree
);
124 static tree
find_case_label_for_value (tree
, tree
);
127 init_empty_tree_cfg (void)
129 /* Initialize the basic block array. */
131 profile_status
= PROFILE_ABSENT
;
133 last_basic_block
= 0;
134 VARRAY_BB_INIT (basic_block_info
, initial_cfg_capacity
, "basic_block_info");
136 /* Build a mapping of labels to their associated blocks. */
137 VARRAY_BB_INIT (label_to_block_map
, initial_cfg_capacity
,
138 "label to block map");
140 ENTRY_BLOCK_PTR
->next_bb
= EXIT_BLOCK_PTR
;
141 EXIT_BLOCK_PTR
->prev_bb
= ENTRY_BLOCK_PTR
;
144 /*---------------------------------------------------------------------------
146 ---------------------------------------------------------------------------*/
148 /* Entry point to the CFG builder for trees. TP points to the list of
149 statements to be added to the flowgraph. */
152 build_tree_cfg (tree
*tp
)
154 /* Register specific tree functions. */
155 tree_register_cfg_hooks ();
157 memset ((void *) &cfg_stats
, 0, sizeof (cfg_stats
));
159 init_empty_tree_cfg ();
161 found_computed_goto
= 0;
164 /* Computed gotos are hell to deal with, especially if there are
165 lots of them with a large number of destinations. So we factor
166 them to a common computed goto location before we build the
167 edge list. After we convert back to normal form, we will un-factor
168 the computed gotos since factoring introduces an unwanted jump. */
169 if (found_computed_goto
)
170 factor_computed_gotos ();
172 /* Make sure there is always at least one block, even if it's empty. */
173 if (n_basic_blocks
== 0)
174 create_empty_bb (ENTRY_BLOCK_PTR
);
176 /* Adjust the size of the array. */
177 VARRAY_GROW (basic_block_info
, n_basic_blocks
);
179 /* To speed up statement iterator walks, we first purge dead labels. */
180 cleanup_dead_labels ();
182 /* Group case nodes to reduce the number of edges.
183 We do this after cleaning up dead labels because otherwise we miss
184 a lot of obvious case merging opportunities. */
185 group_case_labels ();
187 /* Create the edges of the flowgraph. */
190 /* Debugging dumps. */
192 /* Write the flowgraph to a VCG file. */
194 int local_dump_flags
;
195 FILE *dump_file
= dump_begin (TDI_vcg
, &local_dump_flags
);
198 tree_cfg2vcg (dump_file
);
199 dump_end (TDI_vcg
, dump_file
);
203 #ifdef ENABLE_CHECKING
207 /* Dump a textual representation of the flowgraph. */
209 dump_tree_cfg (dump_file
, dump_flags
);
213 execute_build_cfg (void)
215 build_tree_cfg (&DECL_SAVED_TREE (current_function_decl
));
218 struct tree_opt_pass pass_build_cfg
=
222 execute_build_cfg
, /* execute */
225 0, /* static_pass_number */
226 TV_TREE_CFG
, /* tv_id */
227 PROP_gimple_leh
, /* properties_required */
228 PROP_cfg
, /* properties_provided */
229 0, /* properties_destroyed */
230 0, /* todo_flags_start */
231 TODO_verify_stmts
, /* todo_flags_finish */
235 /* Search the CFG for any computed gotos. If found, factor them to a
236 common computed goto site. Also record the location of that site so
237 that we can un-factor the gotos after we have converted back to
241 factor_computed_gotos (void)
244 tree factored_label_decl
= NULL
;
246 tree factored_computed_goto_label
= NULL
;
247 tree factored_computed_goto
= NULL
;
249 /* We know there are one or more computed gotos in this function.
250 Examine the last statement in each basic block to see if the block
251 ends with a computed goto. */
255 block_stmt_iterator bsi
= bsi_last (bb
);
260 last
= bsi_stmt (bsi
);
262 /* Ignore the computed goto we create when we factor the original
264 if (last
== factored_computed_goto
)
267 /* If the last statement is a computed goto, factor it. */
268 if (computed_goto_p (last
))
272 /* The first time we find a computed goto we need to create
273 the factored goto block and the variable each original
274 computed goto will use for their goto destination. */
275 if (! factored_computed_goto
)
277 basic_block new_bb
= create_empty_bb (bb
);
278 block_stmt_iterator new_bsi
= bsi_start (new_bb
);
280 /* Create the destination of the factored goto. Each original
281 computed goto will put its desired destination into this
282 variable and jump to the label we create immediately
284 var
= create_tmp_var (ptr_type_node
, "gotovar");
286 /* Build a label for the new block which will contain the
287 factored computed goto. */
288 factored_label_decl
= create_artificial_label ();
289 factored_computed_goto_label
290 = build1 (LABEL_EXPR
, void_type_node
, factored_label_decl
);
291 bsi_insert_after (&new_bsi
, factored_computed_goto_label
,
294 /* Build our new computed goto. */
295 factored_computed_goto
= build1 (GOTO_EXPR
, void_type_node
, var
);
296 bsi_insert_after (&new_bsi
, factored_computed_goto
,
300 /* Copy the original computed goto's destination into VAR. */
301 assignment
= build (MODIFY_EXPR
, ptr_type_node
,
302 var
, GOTO_DESTINATION (last
));
303 bsi_insert_before (&bsi
, assignment
, BSI_SAME_STMT
);
305 /* And re-vector the computed goto to the new destination. */
306 GOTO_DESTINATION (last
) = factored_label_decl
;
312 /* Build a flowgraph for the statement_list STMT_LIST. */
315 make_blocks (tree stmt_list
)
317 tree_stmt_iterator i
= tsi_start (stmt_list
);
319 bool start_new_block
= true;
320 bool first_stmt_of_list
= true;
321 basic_block bb
= ENTRY_BLOCK_PTR
;
323 while (!tsi_end_p (i
))
330 /* If the statement starts a new basic block or if we have determined
331 in a previous pass that we need to create a new block for STMT, do
333 if (start_new_block
|| stmt_starts_bb_p (stmt
, prev_stmt
))
335 if (!first_stmt_of_list
)
336 stmt_list
= tsi_split_statement_list_before (&i
);
337 bb
= create_basic_block (stmt_list
, NULL
, bb
);
338 start_new_block
= false;
341 /* Now add STMT to BB and create the subgraphs for special statement
343 set_bb_for_stmt (stmt
, bb
);
345 if (computed_goto_p (stmt
))
346 found_computed_goto
= true;
348 /* If STMT is a basic block terminator, set START_NEW_BLOCK for the
350 if (stmt_ends_bb_p (stmt
))
351 start_new_block
= true;
354 first_stmt_of_list
= false;
359 /* Create and return a new empty basic block after bb AFTER. */
362 create_bb (void *h
, void *e
, basic_block after
)
368 /* Create and initialize a new basic block. Since alloc_block uses
369 ggc_alloc_cleared to allocate a basic block, we do not have to
370 clear the newly allocated basic block here. */
373 bb
->index
= last_basic_block
;
375 bb
->stmt_list
= h
? h
: alloc_stmt_list ();
377 /* Add the new block to the linked list of blocks. */
378 link_block (bb
, after
);
380 /* Grow the basic block array if needed. */
381 if ((size_t) last_basic_block
== VARRAY_SIZE (basic_block_info
))
383 size_t new_size
= last_basic_block
+ (last_basic_block
+ 3) / 4;
384 VARRAY_GROW (basic_block_info
, new_size
);
387 /* Add the newly created block to the array. */
388 BASIC_BLOCK (last_basic_block
) = bb
;
393 initialize_bb_rbi (bb
);
398 /*---------------------------------------------------------------------------
400 ---------------------------------------------------------------------------*/
402 /* Fold COND_EXPR_COND of each COND_EXPR. */
405 fold_cond_expr_cond (void)
411 tree stmt
= last_stmt (bb
);
414 && TREE_CODE (stmt
) == COND_EXPR
)
416 tree cond
= fold (COND_EXPR_COND (stmt
));
417 if (integer_zerop (cond
))
418 COND_EXPR_COND (stmt
) = boolean_false_node
;
419 else if (integer_onep (cond
))
420 COND_EXPR_COND (stmt
) = boolean_true_node
;
425 /* Join all the blocks in the flowgraph. */
432 /* Create an edge from entry to the first block with executable
434 make_edge (ENTRY_BLOCK_PTR
, BASIC_BLOCK (0), EDGE_FALLTHRU
);
436 /* Traverse the basic block array placing edges. */
439 tree first
= first_stmt (bb
);
440 tree last
= last_stmt (bb
);
444 /* Edges for statements that always alter flow control. */
445 if (is_ctrl_stmt (last
))
446 make_ctrl_stmt_edges (bb
);
448 /* Edges for statements that sometimes alter flow control. */
449 if (is_ctrl_altering_stmt (last
))
450 make_exit_edges (bb
);
453 /* Finally, if no edges were created above, this is a regular
454 basic block that only needs a fallthru edge. */
455 if (EDGE_COUNT (bb
->succs
) == 0)
456 make_edge (bb
, bb
->next_bb
, EDGE_FALLTHRU
);
459 /* We do not care about fake edges, so remove any that the CFG
460 builder inserted for completeness. */
461 remove_fake_exit_edges ();
463 /* Fold COND_EXPR_COND of each COND_EXPR. */
464 fold_cond_expr_cond ();
466 /* Clean up the graph and warn for unreachable code. */
471 /* Create edges for control statement at basic block BB. */
474 make_ctrl_stmt_edges (basic_block bb
)
476 tree last
= last_stmt (bb
);
479 switch (TREE_CODE (last
))
482 make_goto_expr_edges (bb
);
486 make_edge (bb
, EXIT_BLOCK_PTR
, 0);
490 make_cond_expr_edges (bb
);
494 make_switch_expr_edges (bb
);
498 make_eh_edges (last
);
499 /* Yet another NORETURN hack. */
500 if (EDGE_COUNT (bb
->succs
) == 0)
501 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
510 /* Create exit edges for statements in block BB that alter the flow of
511 control. Statements that alter the control flow are 'goto', 'return'
512 and calls to non-returning functions. */
515 make_exit_edges (basic_block bb
)
517 tree last
= last_stmt (bb
), op
;
520 switch (TREE_CODE (last
))
525 /* If this function receives a nonlocal goto, then we need to
526 make edges from this call site to all the nonlocal goto
528 if (TREE_SIDE_EFFECTS (last
)
529 && current_function_has_nonlocal_label
)
530 make_goto_expr_edges (bb
);
532 /* If this statement has reachable exception handlers, then
533 create abnormal edges to them. */
534 make_eh_edges (last
);
536 /* Some calls are known not to return. For such calls we create
539 We really need to revamp how we build edges so that it's not
540 such a bloody pain to avoid creating edges for this case since
541 all we do is remove these edges when we're done building the
543 if (call_expr_flags (last
) & ECF_NORETURN
)
545 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
549 /* Don't forget the fall-thru edge. */
550 make_edge (bb
, bb
->next_bb
, EDGE_FALLTHRU
);
554 /* A MODIFY_EXPR may have a CALL_EXPR on its RHS and the CALL_EXPR
555 may have an abnormal edge. Search the RHS for this case and
556 create any required edges. */
557 op
= get_call_expr_in (last
);
558 if (op
&& TREE_SIDE_EFFECTS (op
)
559 && current_function_has_nonlocal_label
)
560 make_goto_expr_edges (bb
);
562 make_eh_edges (last
);
563 make_edge (bb
, bb
->next_bb
, EDGE_FALLTHRU
);
572 /* Create the edges for a COND_EXPR starting at block BB.
573 At this point, both clauses must contain only simple gotos. */
576 make_cond_expr_edges (basic_block bb
)
578 tree entry
= last_stmt (bb
);
579 basic_block then_bb
, else_bb
;
580 tree then_label
, else_label
;
583 gcc_assert (TREE_CODE (entry
) == COND_EXPR
);
585 /* Entry basic blocks for each component. */
586 then_label
= GOTO_DESTINATION (COND_EXPR_THEN (entry
));
587 else_label
= GOTO_DESTINATION (COND_EXPR_ELSE (entry
));
588 then_bb
= label_to_block (then_label
);
589 else_bb
= label_to_block (else_label
);
591 make_edge (bb
, then_bb
, EDGE_TRUE_VALUE
);
592 make_edge (bb
, else_bb
, EDGE_FALSE_VALUE
);
595 /* Hashing routine for EDGE_TO_CASES. */
598 edge_to_cases_hash (const void *p
)
600 edge e
= ((struct edge_to_cases_elt
*)p
)->e
;
602 /* Hash on the edge itself (which is a pointer). */
603 return htab_hash_pointer (e
);
606 /* Equality routine for EDGE_TO_CASES, edges are unique, so testing
607 for equality is just a pointer comparison. */
610 edge_to_cases_eq (const void *p1
, const void *p2
)
612 edge e1
= ((struct edge_to_cases_elt
*)p1
)->e
;
613 edge e2
= ((struct edge_to_cases_elt
*)p2
)->e
;
618 /* Called for each element in the hash table (P) as we delete the
619 edge to cases hash table.
621 Clear all the TREE_CHAINs to prevent problems with copying of
622 SWITCH_EXPRs and structure sharing rules, then free the hash table
626 edge_to_cases_cleanup (void *p
)
628 struct edge_to_cases_elt
*elt
= p
;
631 for (t
= elt
->case_labels
; t
; t
= next
)
633 next
= TREE_CHAIN (t
);
634 TREE_CHAIN (t
) = NULL
;
639 /* Start recording information mapping edges to case labels. */
642 start_recording_case_labels (void)
644 gcc_assert (edge_to_cases
== NULL
);
646 edge_to_cases
= htab_create (37,
649 edge_to_cases_cleanup
);
652 /* Return nonzero if we are recording information for case labels. */
655 recording_case_labels_p (void)
657 return (edge_to_cases
!= NULL
);
660 /* Stop recording information mapping edges to case labels and
661 remove any information we have recorded. */
663 end_recording_case_labels (void)
665 htab_delete (edge_to_cases
);
666 edge_to_cases
= NULL
;
669 /* Record that CASE_LABEL (a CASE_LABEL_EXPR) references edge E. */
672 record_switch_edge (edge e
, tree case_label
)
674 struct edge_to_cases_elt
*elt
;
677 /* Build a hash table element so we can see if E is already
679 elt
= xmalloc (sizeof (struct edge_to_cases_elt
));
681 elt
->case_labels
= case_label
;
683 slot
= htab_find_slot (edge_to_cases
, elt
, INSERT
);
687 /* E was not in the hash table. Install E into the hash table. */
692 /* E was already in the hash table. Free ELT as we do not need it
696 /* Get the entry stored in the hash table. */
697 elt
= (struct edge_to_cases_elt
*) *slot
;
699 /* Add it to the chain of CASE_LABEL_EXPRs referencing E. */
700 TREE_CHAIN (case_label
) = elt
->case_labels
;
701 elt
->case_labels
= case_label
;
705 /* If we are inside a {start,end}_recording_cases block, then return
706 a chain of CASE_LABEL_EXPRs from T which reference E.
708 Otherwise return NULL. */
711 get_cases_for_edge (edge e
, tree t
)
713 struct edge_to_cases_elt elt
, *elt_p
;
718 /* If we are not recording cases, then we do not have CASE_LABEL_EXPR
719 chains available. Return NULL so the caller can detect this case. */
720 if (!recording_case_labels_p ())
725 elt
.case_labels
= NULL
;
726 slot
= htab_find_slot (edge_to_cases
, &elt
, NO_INSERT
);
730 elt_p
= (struct edge_to_cases_elt
*)*slot
;
731 return elt_p
->case_labels
;
734 /* If we did not find E in the hash table, then this must be the first
735 time we have been queried for information about E & T. Add all the
736 elements from T to the hash table then perform the query again. */
738 vec
= SWITCH_LABELS (t
);
739 n
= TREE_VEC_LENGTH (vec
);
740 for (i
= 0; i
< n
; i
++)
742 tree lab
= CASE_LABEL (TREE_VEC_ELT (vec
, i
));
743 basic_block label_bb
= label_to_block (lab
);
744 record_switch_edge (find_edge (e
->src
, label_bb
), TREE_VEC_ELT (vec
, i
));
749 /* Create the edges for a SWITCH_EXPR starting at block BB.
750 At this point, the switch body has been lowered and the
751 SWITCH_LABELS filled in, so this is in effect a multi-way branch. */
754 make_switch_expr_edges (basic_block bb
)
756 tree entry
= last_stmt (bb
);
760 vec
= SWITCH_LABELS (entry
);
761 n
= TREE_VEC_LENGTH (vec
);
763 for (i
= 0; i
< n
; ++i
)
765 tree lab
= CASE_LABEL (TREE_VEC_ELT (vec
, i
));
766 basic_block label_bb
= label_to_block (lab
);
767 make_edge (bb
, label_bb
, 0);
772 /* Return the basic block holding label DEST. */
775 label_to_block_fn (struct function
*ifun
, tree dest
)
777 int uid
= LABEL_DECL_UID (dest
);
779 /* We would die hard when faced by an undefined label. Emit a label to
780 the very first basic block. This will hopefully make even the dataflow
781 and undefined variable warnings quite right. */
782 if ((errorcount
|| sorrycount
) && uid
< 0)
784 block_stmt_iterator bsi
= bsi_start (BASIC_BLOCK (0));
787 stmt
= build1 (LABEL_EXPR
, void_type_node
, dest
);
788 bsi_insert_before (&bsi
, stmt
, BSI_NEW_STMT
);
789 uid
= LABEL_DECL_UID (dest
);
791 if (VARRAY_SIZE (ifun
->cfg
->x_label_to_block_map
) <= (unsigned int)uid
)
793 return VARRAY_BB (ifun
->cfg
->x_label_to_block_map
, uid
);
796 /* Create edges for a goto statement at block BB. */
799 make_goto_expr_edges (basic_block bb
)
802 basic_block target_bb
;
804 block_stmt_iterator last
= bsi_last (bb
);
806 goto_t
= bsi_stmt (last
);
808 /* If the last statement is not a GOTO (i.e., it is a RETURN_EXPR,
809 CALL_EXPR or MODIFY_EXPR), then the edge is an abnormal edge resulting
810 from a nonlocal goto. */
811 if (TREE_CODE (goto_t
) != GOTO_EXPR
)
815 tree dest
= GOTO_DESTINATION (goto_t
);
818 /* A GOTO to a local label creates normal edges. */
819 if (simple_goto_p (goto_t
))
821 edge e
= make_edge (bb
, label_to_block (dest
), EDGE_FALLTHRU
);
822 #ifdef USE_MAPPED_LOCATION
823 e
->goto_locus
= EXPR_LOCATION (goto_t
);
825 e
->goto_locus
= EXPR_LOCUS (goto_t
);
831 /* Nothing more to do for nonlocal gotos. */
832 if (TREE_CODE (dest
) == LABEL_DECL
)
835 /* Computed gotos remain. */
838 /* Look for the block starting with the destination label. In the
839 case of a computed goto, make an edge to any label block we find
841 FOR_EACH_BB (target_bb
)
843 block_stmt_iterator bsi
;
845 for (bsi
= bsi_start (target_bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
847 tree target
= bsi_stmt (bsi
);
849 if (TREE_CODE (target
) != LABEL_EXPR
)
853 /* Computed GOTOs. Make an edge to every label block that has
854 been marked as a potential target for a computed goto. */
855 (FORCED_LABEL (LABEL_EXPR_LABEL (target
)) && for_call
== 0)
856 /* Nonlocal GOTO target. Make an edge to every label block
857 that has been marked as a potential target for a nonlocal
859 || (DECL_NONLOCAL (LABEL_EXPR_LABEL (target
)) && for_call
== 1))
861 make_edge (bb
, target_bb
, EDGE_ABNORMAL
);
867 /* Degenerate case of computed goto with no labels. */
868 if (!for_call
&& EDGE_COUNT (bb
->succs
) == 0)
869 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
873 /*---------------------------------------------------------------------------
875 ---------------------------------------------------------------------------*/
877 /* Cleanup useless labels in basic blocks. This is something we wish
878 to do early because it allows us to group case labels before creating
879 the edges for the CFG, and it speeds up block statement iterators in
881 We only run this pass once, running it more than once is probably not
884 /* A map from basic block index to the leading label of that block. */
885 static tree
*label_for_bb
;
887 /* Callback for for_each_eh_region. Helper for cleanup_dead_labels. */
889 update_eh_label (struct eh_region
*region
)
891 tree old_label
= get_eh_region_tree_label (region
);
895 basic_block bb
= label_to_block (old_label
);
897 /* ??? After optimizing, there may be EH regions with labels
898 that have already been removed from the function body, so
899 there is no basic block for them. */
903 new_label
= label_for_bb
[bb
->index
];
904 set_eh_region_tree_label (region
, new_label
);
908 /* Given LABEL return the first label in the same basic block. */
910 main_block_label (tree label
)
912 basic_block bb
= label_to_block (label
);
914 /* label_to_block possibly inserted undefined label into the chain. */
915 if (!label_for_bb
[bb
->index
])
916 label_for_bb
[bb
->index
] = label
;
917 return label_for_bb
[bb
->index
];
920 /* Cleanup redundant labels. This is a three-step process:
921 1) Find the leading label for each block.
922 2) Redirect all references to labels to the leading labels.
923 3) Cleanup all useless labels. */
926 cleanup_dead_labels (void)
929 label_for_bb
= xcalloc (last_basic_block
, sizeof (tree
));
931 /* Find a suitable label for each block. We use the first user-defined
932 label if there is one, or otherwise just the first label we see. */
935 block_stmt_iterator i
;
937 for (i
= bsi_start (bb
); !bsi_end_p (i
); bsi_next (&i
))
939 tree label
, stmt
= bsi_stmt (i
);
941 if (TREE_CODE (stmt
) != LABEL_EXPR
)
944 label
= LABEL_EXPR_LABEL (stmt
);
946 /* If we have not yet seen a label for the current block,
947 remember this one and see if there are more labels. */
948 if (! label_for_bb
[bb
->index
])
950 label_for_bb
[bb
->index
] = label
;
954 /* If we did see a label for the current block already, but it
955 is an artificially created label, replace it if the current
956 label is a user defined label. */
957 if (! DECL_ARTIFICIAL (label
)
958 && DECL_ARTIFICIAL (label_for_bb
[bb
->index
]))
960 label_for_bb
[bb
->index
] = label
;
966 /* Now redirect all jumps/branches to the selected label.
967 First do so for each block ending in a control statement. */
970 tree stmt
= last_stmt (bb
);
974 switch (TREE_CODE (stmt
))
978 tree true_branch
, false_branch
;
980 true_branch
= COND_EXPR_THEN (stmt
);
981 false_branch
= COND_EXPR_ELSE (stmt
);
983 GOTO_DESTINATION (true_branch
)
984 = main_block_label (GOTO_DESTINATION (true_branch
));
985 GOTO_DESTINATION (false_branch
)
986 = main_block_label (GOTO_DESTINATION (false_branch
));
994 tree vec
= SWITCH_LABELS (stmt
);
995 size_t n
= TREE_VEC_LENGTH (vec
);
997 /* Replace all destination labels. */
998 for (i
= 0; i
< n
; ++i
)
1000 tree elt
= TREE_VEC_ELT (vec
, i
);
1001 tree label
= main_block_label (CASE_LABEL (elt
));
1002 CASE_LABEL (elt
) = label
;
1007 /* We have to handle GOTO_EXPRs until they're removed, and we don't
1008 remove them until after we've created the CFG edges. */
1010 if (! computed_goto_p (stmt
))
1012 GOTO_DESTINATION (stmt
)
1013 = main_block_label (GOTO_DESTINATION (stmt
));
1022 for_each_eh_region (update_eh_label
);
1024 /* Finally, purge dead labels. All user-defined labels and labels that
1025 can be the target of non-local gotos are preserved. */
1028 block_stmt_iterator i
;
1029 tree label_for_this_bb
= label_for_bb
[bb
->index
];
1031 if (! label_for_this_bb
)
1034 for (i
= bsi_start (bb
); !bsi_end_p (i
); )
1036 tree label
, stmt
= bsi_stmt (i
);
1038 if (TREE_CODE (stmt
) != LABEL_EXPR
)
1041 label
= LABEL_EXPR_LABEL (stmt
);
1043 if (label
== label_for_this_bb
1044 || ! DECL_ARTIFICIAL (label
)
1045 || DECL_NONLOCAL (label
))
1052 free (label_for_bb
);
1055 /* Look for blocks ending in a multiway branch (a SWITCH_EXPR in GIMPLE),
1056 and scan the sorted vector of cases. Combine the ones jumping to the
1058 Eg. three separate entries 1: 2: 3: become one entry 1..3: */
1061 group_case_labels (void)
1067 tree stmt
= last_stmt (bb
);
1068 if (stmt
&& TREE_CODE (stmt
) == SWITCH_EXPR
)
1070 tree labels
= SWITCH_LABELS (stmt
);
1071 int old_size
= TREE_VEC_LENGTH (labels
);
1072 int i
, j
, new_size
= old_size
;
1073 tree default_case
= TREE_VEC_ELT (labels
, old_size
- 1);
1076 /* The default label is always the last case in a switch
1077 statement after gimplification. */
1078 default_label
= CASE_LABEL (default_case
);
1080 /* Look for possible opportunities to merge cases.
1081 Ignore the last element of the label vector because it
1082 must be the default case. */
1084 while (i
< old_size
- 1)
1086 tree base_case
, base_label
, base_high
;
1087 base_case
= TREE_VEC_ELT (labels
, i
);
1089 gcc_assert (base_case
);
1090 base_label
= CASE_LABEL (base_case
);
1092 /* Discard cases that have the same destination as the
1094 if (base_label
== default_label
)
1096 TREE_VEC_ELT (labels
, i
) = NULL_TREE
;
1102 base_high
= CASE_HIGH (base_case
) ?
1103 CASE_HIGH (base_case
) : CASE_LOW (base_case
);
1105 /* Try to merge case labels. Break out when we reach the end
1106 of the label vector or when we cannot merge the next case
1107 label with the current one. */
1108 while (i
< old_size
- 1)
1110 tree merge_case
= TREE_VEC_ELT (labels
, i
);
1111 tree merge_label
= CASE_LABEL (merge_case
);
1112 tree t
= int_const_binop (PLUS_EXPR
, base_high
,
1113 integer_one_node
, 1);
1115 /* Merge the cases if they jump to the same place,
1116 and their ranges are consecutive. */
1117 if (merge_label
== base_label
1118 && tree_int_cst_equal (CASE_LOW (merge_case
), t
))
1120 base_high
= CASE_HIGH (merge_case
) ?
1121 CASE_HIGH (merge_case
) : CASE_LOW (merge_case
);
1122 CASE_HIGH (base_case
) = base_high
;
1123 TREE_VEC_ELT (labels
, i
) = NULL_TREE
;
1132 /* Compress the case labels in the label vector, and adjust the
1133 length of the vector. */
1134 for (i
= 0, j
= 0; i
< new_size
; i
++)
1136 while (! TREE_VEC_ELT (labels
, j
))
1138 TREE_VEC_ELT (labels
, i
) = TREE_VEC_ELT (labels
, j
++);
1140 TREE_VEC_LENGTH (labels
) = new_size
;
1145 /* Checks whether we can merge block B into block A. */
1148 tree_can_merge_blocks_p (basic_block a
, basic_block b
)
1151 block_stmt_iterator bsi
;
1154 if (!single_succ_p (a
))
1157 if (single_succ_edge (a
)->flags
& EDGE_ABNORMAL
)
1160 if (single_succ (a
) != b
)
1163 if (!single_pred_p (b
))
1166 if (b
== EXIT_BLOCK_PTR
)
1169 /* If A ends by a statement causing exceptions or something similar, we
1170 cannot merge the blocks. */
1171 stmt
= last_stmt (a
);
1172 if (stmt
&& stmt_ends_bb_p (stmt
))
1175 /* Do not allow a block with only a non-local label to be merged. */
1176 if (stmt
&& TREE_CODE (stmt
) == LABEL_EXPR
1177 && DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt
)))
1180 /* It must be possible to eliminate all phi nodes in B. If ssa form
1181 is not up-to-date, we cannot eliminate any phis. */
1182 phi
= phi_nodes (b
);
1185 if (need_ssa_update_p ())
1188 for (; phi
; phi
= PHI_CHAIN (phi
))
1189 if (!is_gimple_reg (PHI_RESULT (phi
))
1190 && !may_propagate_copy (PHI_RESULT (phi
), PHI_ARG_DEF (phi
, 0)))
1194 /* Do not remove user labels. */
1195 for (bsi
= bsi_start (b
); !bsi_end_p (bsi
); bsi_next (&bsi
))
1197 stmt
= bsi_stmt (bsi
);
1198 if (TREE_CODE (stmt
) != LABEL_EXPR
)
1200 if (!DECL_ARTIFICIAL (LABEL_EXPR_LABEL (stmt
)))
1204 /* Protect the loop latches. */
1206 && b
->loop_father
->latch
== b
)
1212 /* Replaces all uses of NAME by VAL. */
1215 replace_uses_by (tree name
, tree val
)
1217 imm_use_iterator imm_iter
;
1222 VEC(tree
,heap
) *stmts
= VEC_alloc (tree
, heap
, 20);
1224 FOR_EACH_IMM_USE_SAFE (use
, imm_iter
, name
)
1226 stmt
= USE_STMT (use
);
1230 if (TREE_CODE (stmt
) == PHI_NODE
)
1232 e
= PHI_ARG_EDGE (stmt
, PHI_ARG_INDEX_FROM_USE (use
));
1233 if (e
->flags
& EDGE_ABNORMAL
)
1235 /* This can only occur for virtual operands, since
1236 for the real ones SSA_NAME_OCCURS_IN_ABNORMAL_PHI (name))
1237 would prevent replacement. */
1238 gcc_assert (!is_gimple_reg (name
));
1239 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (val
) = 1;
1243 VEC_safe_push (tree
, heap
, stmts
, stmt
);
1246 /* We do not update the statements in the loop above. Consider
1249 If we performed the update in the first loop, the statement
1250 would be rescanned after first occurrence of w is replaced,
1251 the new uses would be placed to the beginning of the list,
1252 and we would never process them. */
1253 for (i
= 0; VEC_iterate (tree
, stmts
, i
, stmt
); i
++)
1257 fold_stmt_inplace (stmt
);
1259 rhs
= get_rhs (stmt
);
1260 if (TREE_CODE (rhs
) == ADDR_EXPR
)
1261 recompute_tree_invarant_for_addr_expr (rhs
);
1266 VEC_free (tree
, heap
, stmts
);
1269 /* Merge block B into block A. */
1272 tree_merge_blocks (basic_block a
, basic_block b
)
1274 block_stmt_iterator bsi
;
1275 tree_stmt_iterator last
;
1279 fprintf (dump_file
, "Merging blocks %d and %d\n", a
->index
, b
->index
);
1281 /* Remove the phi nodes. */
1283 for (phi
= phi_nodes (b
); phi
; phi
= phi_nodes (b
))
1285 tree def
= PHI_RESULT (phi
), use
= PHI_ARG_DEF (phi
, 0);
1288 if (!may_propagate_copy (def
, use
)
1289 /* Propagating pointers might cause the set of vops for statements
1290 to be changed, and thus require ssa form update. */
1291 || (is_gimple_reg (def
)
1292 && POINTER_TYPE_P (TREE_TYPE (def
))))
1294 gcc_assert (is_gimple_reg (def
));
1296 /* Note that just emitting the copies is fine -- there is no problem
1297 with ordering of phi nodes. This is because A is the single
1298 predecessor of B, therefore results of the phi nodes cannot
1299 appear as arguments of the phi nodes. */
1300 copy
= build2 (MODIFY_EXPR
, void_type_node
, def
, use
);
1301 bsi_insert_after (&bsi
, copy
, BSI_NEW_STMT
);
1302 SET_PHI_RESULT (phi
, NULL_TREE
);
1303 SSA_NAME_DEF_STMT (def
) = copy
;
1306 replace_uses_by (def
, use
);
1307 remove_phi_node (phi
, NULL
);
1310 /* Ensure that B follows A. */
1311 move_block_after (b
, a
);
1313 gcc_assert (single_succ_edge (a
)->flags
& EDGE_FALLTHRU
);
1314 gcc_assert (!last_stmt (a
) || !stmt_ends_bb_p (last_stmt (a
)));
1316 /* Remove labels from B and set bb_for_stmt to A for other statements. */
1317 for (bsi
= bsi_start (b
); !bsi_end_p (bsi
);)
1319 if (TREE_CODE (bsi_stmt (bsi
)) == LABEL_EXPR
)
1321 tree label
= bsi_stmt (bsi
);
1324 /* Now that we can thread computed gotos, we might have
1325 a situation where we have a forced label in block B
1326 However, the label at the start of block B might still be
1327 used in other ways (think about the runtime checking for
1328 Fortran assigned gotos). So we can not just delete the
1329 label. Instead we move the label to the start of block A. */
1330 if (FORCED_LABEL (LABEL_EXPR_LABEL (label
)))
1332 block_stmt_iterator dest_bsi
= bsi_start (a
);
1333 bsi_insert_before (&dest_bsi
, label
, BSI_NEW_STMT
);
1338 set_bb_for_stmt (bsi_stmt (bsi
), a
);
1343 /* Merge the chains. */
1344 last
= tsi_last (a
->stmt_list
);
1345 tsi_link_after (&last
, b
->stmt_list
, TSI_NEW_STMT
);
1346 b
->stmt_list
= NULL
;
1350 /* Walk the function tree removing unnecessary statements.
1352 * Empty statement nodes are removed
1354 * Unnecessary TRY_FINALLY and TRY_CATCH blocks are removed
1356 * Unnecessary COND_EXPRs are removed
1358 * Some unnecessary BIND_EXPRs are removed
1360 Clearly more work could be done. The trick is doing the analysis
1361 and removal fast enough to be a net improvement in compile times.
1363 Note that when we remove a control structure such as a COND_EXPR
1364 BIND_EXPR, or TRY block, we will need to repeat this optimization pass
1365 to ensure we eliminate all the useless code. */
1376 static void remove_useless_stmts_1 (tree
*, struct rus_data
*);
1379 remove_useless_stmts_warn_notreached (tree stmt
)
1381 if (EXPR_HAS_LOCATION (stmt
))
1383 location_t loc
= EXPR_LOCATION (stmt
);
1384 if (LOCATION_LINE (loc
) > 0)
1386 warning (0, "%Hwill never be executed", &loc
);
1391 switch (TREE_CODE (stmt
))
1393 case STATEMENT_LIST
:
1395 tree_stmt_iterator i
;
1396 for (i
= tsi_start (stmt
); !tsi_end_p (i
); tsi_next (&i
))
1397 if (remove_useless_stmts_warn_notreached (tsi_stmt (i
)))
1403 if (remove_useless_stmts_warn_notreached (COND_EXPR_COND (stmt
)))
1405 if (remove_useless_stmts_warn_notreached (COND_EXPR_THEN (stmt
)))
1407 if (remove_useless_stmts_warn_notreached (COND_EXPR_ELSE (stmt
)))
1411 case TRY_FINALLY_EXPR
:
1412 case TRY_CATCH_EXPR
:
1413 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt
, 0)))
1415 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt
, 1)))
1420 return remove_useless_stmts_warn_notreached (CATCH_BODY (stmt
));
1421 case EH_FILTER_EXPR
:
1422 return remove_useless_stmts_warn_notreached (EH_FILTER_FAILURE (stmt
));
1424 return remove_useless_stmts_warn_notreached (BIND_EXPR_BLOCK (stmt
));
1427 /* Not a live container. */
1435 remove_useless_stmts_cond (tree
*stmt_p
, struct rus_data
*data
)
1437 tree then_clause
, else_clause
, cond
;
1438 bool save_has_label
, then_has_label
, else_has_label
;
1440 save_has_label
= data
->has_label
;
1441 data
->has_label
= false;
1442 data
->last_goto
= NULL
;
1444 remove_useless_stmts_1 (&COND_EXPR_THEN (*stmt_p
), data
);
1446 then_has_label
= data
->has_label
;
1447 data
->has_label
= false;
1448 data
->last_goto
= NULL
;
1450 remove_useless_stmts_1 (&COND_EXPR_ELSE (*stmt_p
), data
);
1452 else_has_label
= data
->has_label
;
1453 data
->has_label
= save_has_label
| then_has_label
| else_has_label
;
1455 then_clause
= COND_EXPR_THEN (*stmt_p
);
1456 else_clause
= COND_EXPR_ELSE (*stmt_p
);
1457 cond
= fold (COND_EXPR_COND (*stmt_p
));
1459 /* If neither arm does anything at all, we can remove the whole IF. */
1460 if (!TREE_SIDE_EFFECTS (then_clause
) && !TREE_SIDE_EFFECTS (else_clause
))
1462 *stmt_p
= build_empty_stmt ();
1463 data
->repeat
= true;
1466 /* If there are no reachable statements in an arm, then we can
1467 zap the entire conditional. */
1468 else if (integer_nonzerop (cond
) && !else_has_label
)
1470 if (warn_notreached
)
1471 remove_useless_stmts_warn_notreached (else_clause
);
1472 *stmt_p
= then_clause
;
1473 data
->repeat
= true;
1475 else if (integer_zerop (cond
) && !then_has_label
)
1477 if (warn_notreached
)
1478 remove_useless_stmts_warn_notreached (then_clause
);
1479 *stmt_p
= else_clause
;
1480 data
->repeat
= true;
1483 /* Check a couple of simple things on then/else with single stmts. */
1486 tree then_stmt
= expr_only (then_clause
);
1487 tree else_stmt
= expr_only (else_clause
);
1489 /* Notice branches to a common destination. */
1490 if (then_stmt
&& else_stmt
1491 && TREE_CODE (then_stmt
) == GOTO_EXPR
1492 && TREE_CODE (else_stmt
) == GOTO_EXPR
1493 && (GOTO_DESTINATION (then_stmt
) == GOTO_DESTINATION (else_stmt
)))
1495 *stmt_p
= then_stmt
;
1496 data
->repeat
= true;
1499 /* If the THEN/ELSE clause merely assigns a value to a variable or
1500 parameter which is already known to contain that value, then
1501 remove the useless THEN/ELSE clause. */
1502 else if (TREE_CODE (cond
) == VAR_DECL
|| TREE_CODE (cond
) == PARM_DECL
)
1505 && TREE_CODE (else_stmt
) == MODIFY_EXPR
1506 && TREE_OPERAND (else_stmt
, 0) == cond
1507 && integer_zerop (TREE_OPERAND (else_stmt
, 1)))
1508 COND_EXPR_ELSE (*stmt_p
) = alloc_stmt_list ();
1510 else if ((TREE_CODE (cond
) == EQ_EXPR
|| TREE_CODE (cond
) == NE_EXPR
)
1511 && (TREE_CODE (TREE_OPERAND (cond
, 0)) == VAR_DECL
1512 || TREE_CODE (TREE_OPERAND (cond
, 0)) == PARM_DECL
)
1513 && TREE_CONSTANT (TREE_OPERAND (cond
, 1)))
1515 tree stmt
= (TREE_CODE (cond
) == EQ_EXPR
1516 ? then_stmt
: else_stmt
);
1517 tree
*location
= (TREE_CODE (cond
) == EQ_EXPR
1518 ? &COND_EXPR_THEN (*stmt_p
)
1519 : &COND_EXPR_ELSE (*stmt_p
));
1522 && TREE_CODE (stmt
) == MODIFY_EXPR
1523 && TREE_OPERAND (stmt
, 0) == TREE_OPERAND (cond
, 0)
1524 && TREE_OPERAND (stmt
, 1) == TREE_OPERAND (cond
, 1))
1525 *location
= alloc_stmt_list ();
1529 /* Protect GOTOs in the arm of COND_EXPRs from being removed. They
1530 would be re-introduced during lowering. */
1531 data
->last_goto
= NULL
;
1536 remove_useless_stmts_tf (tree
*stmt_p
, struct rus_data
*data
)
1538 bool save_may_branch
, save_may_throw
;
1539 bool this_may_branch
, this_may_throw
;
1541 /* Collect may_branch and may_throw information for the body only. */
1542 save_may_branch
= data
->may_branch
;
1543 save_may_throw
= data
->may_throw
;
1544 data
->may_branch
= false;
1545 data
->may_throw
= false;
1546 data
->last_goto
= NULL
;
1548 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p
, 0), data
);
1550 this_may_branch
= data
->may_branch
;
1551 this_may_throw
= data
->may_throw
;
1552 data
->may_branch
|= save_may_branch
;
1553 data
->may_throw
|= save_may_throw
;
1554 data
->last_goto
= NULL
;
1556 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p
, 1), data
);
1558 /* If the body is empty, then we can emit the FINALLY block without
1559 the enclosing TRY_FINALLY_EXPR. */
1560 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p
, 0)))
1562 *stmt_p
= TREE_OPERAND (*stmt_p
, 1);
1563 data
->repeat
= true;
1566 /* If the handler is empty, then we can emit the TRY block without
1567 the enclosing TRY_FINALLY_EXPR. */
1568 else if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p
, 1)))
1570 *stmt_p
= TREE_OPERAND (*stmt_p
, 0);
1571 data
->repeat
= true;
1574 /* If the body neither throws, nor branches, then we can safely
1575 string the TRY and FINALLY blocks together. */
1576 else if (!this_may_branch
&& !this_may_throw
)
1578 tree stmt
= *stmt_p
;
1579 *stmt_p
= TREE_OPERAND (stmt
, 0);
1580 append_to_statement_list (TREE_OPERAND (stmt
, 1), stmt_p
);
1581 data
->repeat
= true;
1587 remove_useless_stmts_tc (tree
*stmt_p
, struct rus_data
*data
)
1589 bool save_may_throw
, this_may_throw
;
1590 tree_stmt_iterator i
;
1593 /* Collect may_throw information for the body only. */
1594 save_may_throw
= data
->may_throw
;
1595 data
->may_throw
= false;
1596 data
->last_goto
= NULL
;
1598 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p
, 0), data
);
1600 this_may_throw
= data
->may_throw
;
1601 data
->may_throw
= save_may_throw
;
1603 /* If the body cannot throw, then we can drop the entire TRY_CATCH_EXPR. */
1604 if (!this_may_throw
)
1606 if (warn_notreached
)
1607 remove_useless_stmts_warn_notreached (TREE_OPERAND (*stmt_p
, 1));
1608 *stmt_p
= TREE_OPERAND (*stmt_p
, 0);
1609 data
->repeat
= true;
1613 /* Process the catch clause specially. We may be able to tell that
1614 no exceptions propagate past this point. */
1616 this_may_throw
= true;
1617 i
= tsi_start (TREE_OPERAND (*stmt_p
, 1));
1618 stmt
= tsi_stmt (i
);
1619 data
->last_goto
= NULL
;
1621 switch (TREE_CODE (stmt
))
1624 for (; !tsi_end_p (i
); tsi_next (&i
))
1626 stmt
= tsi_stmt (i
);
1627 /* If we catch all exceptions, then the body does not
1628 propagate exceptions past this point. */
1629 if (CATCH_TYPES (stmt
) == NULL
)
1630 this_may_throw
= false;
1631 data
->last_goto
= NULL
;
1632 remove_useless_stmts_1 (&CATCH_BODY (stmt
), data
);
1636 case EH_FILTER_EXPR
:
1637 if (EH_FILTER_MUST_NOT_THROW (stmt
))
1638 this_may_throw
= false;
1639 else if (EH_FILTER_TYPES (stmt
) == NULL
)
1640 this_may_throw
= false;
1641 remove_useless_stmts_1 (&EH_FILTER_FAILURE (stmt
), data
);
1645 /* Otherwise this is a cleanup. */
1646 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p
, 1), data
);
1648 /* If the cleanup is empty, then we can emit the TRY block without
1649 the enclosing TRY_CATCH_EXPR. */
1650 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p
, 1)))
1652 *stmt_p
= TREE_OPERAND (*stmt_p
, 0);
1653 data
->repeat
= true;
1657 data
->may_throw
|= this_may_throw
;
1662 remove_useless_stmts_bind (tree
*stmt_p
, struct rus_data
*data
)
1666 /* First remove anything underneath the BIND_EXPR. */
1667 remove_useless_stmts_1 (&BIND_EXPR_BODY (*stmt_p
), data
);
1669 /* If the BIND_EXPR has no variables, then we can pull everything
1670 up one level and remove the BIND_EXPR, unless this is the toplevel
1671 BIND_EXPR for the current function or an inlined function.
1673 When this situation occurs we will want to apply this
1674 optimization again. */
1675 block
= BIND_EXPR_BLOCK (*stmt_p
);
1676 if (BIND_EXPR_VARS (*stmt_p
) == NULL_TREE
1677 && *stmt_p
!= DECL_SAVED_TREE (current_function_decl
)
1679 || ! BLOCK_ABSTRACT_ORIGIN (block
)
1680 || (TREE_CODE (BLOCK_ABSTRACT_ORIGIN (block
))
1683 *stmt_p
= BIND_EXPR_BODY (*stmt_p
);
1684 data
->repeat
= true;
1690 remove_useless_stmts_goto (tree
*stmt_p
, struct rus_data
*data
)
1692 tree dest
= GOTO_DESTINATION (*stmt_p
);
1694 data
->may_branch
= true;
1695 data
->last_goto
= NULL
;
1697 /* Record the last goto expr, so that we can delete it if unnecessary. */
1698 if (TREE_CODE (dest
) == LABEL_DECL
)
1699 data
->last_goto
= stmt_p
;
1704 remove_useless_stmts_label (tree
*stmt_p
, struct rus_data
*data
)
1706 tree label
= LABEL_EXPR_LABEL (*stmt_p
);
1708 data
->has_label
= true;
1710 /* We do want to jump across non-local label receiver code. */
1711 if (DECL_NONLOCAL (label
))
1712 data
->last_goto
= NULL
;
1714 else if (data
->last_goto
&& GOTO_DESTINATION (*data
->last_goto
) == label
)
1716 *data
->last_goto
= build_empty_stmt ();
1717 data
->repeat
= true;
1720 /* ??? Add something here to delete unused labels. */
1724 /* If the function is "const" or "pure", then clear TREE_SIDE_EFFECTS on its
1725 decl. This allows us to eliminate redundant or useless
1726 calls to "const" functions.
1728 Gimplifier already does the same operation, but we may notice functions
1729 being const and pure once their calls has been gimplified, so we need
1730 to update the flag. */
1733 update_call_expr_flags (tree call
)
1735 tree decl
= get_callee_fndecl (call
);
1738 if (call_expr_flags (call
) & (ECF_CONST
| ECF_PURE
))
1739 TREE_SIDE_EFFECTS (call
) = 0;
1740 if (TREE_NOTHROW (decl
))
1741 TREE_NOTHROW (call
) = 1;
1745 /* T is CALL_EXPR. Set current_function_calls_* flags. */
1748 notice_special_calls (tree t
)
1750 int flags
= call_expr_flags (t
);
1752 if (flags
& ECF_MAY_BE_ALLOCA
)
1753 current_function_calls_alloca
= true;
1754 if (flags
& ECF_RETURNS_TWICE
)
1755 current_function_calls_setjmp
= true;
1759 /* Clear flags set by notice_special_calls. Used by dead code removal
1760 to update the flags. */
1763 clear_special_calls (void)
1765 current_function_calls_alloca
= false;
1766 current_function_calls_setjmp
= false;
1771 remove_useless_stmts_1 (tree
*tp
, struct rus_data
*data
)
1775 switch (TREE_CODE (t
))
1778 remove_useless_stmts_cond (tp
, data
);
1781 case TRY_FINALLY_EXPR
:
1782 remove_useless_stmts_tf (tp
, data
);
1785 case TRY_CATCH_EXPR
:
1786 remove_useless_stmts_tc (tp
, data
);
1790 remove_useless_stmts_bind (tp
, data
);
1794 remove_useless_stmts_goto (tp
, data
);
1798 remove_useless_stmts_label (tp
, data
);
1803 data
->last_goto
= NULL
;
1804 data
->may_branch
= true;
1809 data
->last_goto
= NULL
;
1810 notice_special_calls (t
);
1811 update_call_expr_flags (t
);
1812 if (tree_could_throw_p (t
))
1813 data
->may_throw
= true;
1817 data
->last_goto
= NULL
;
1819 op
= get_call_expr_in (t
);
1822 update_call_expr_flags (op
);
1823 notice_special_calls (op
);
1825 if (tree_could_throw_p (t
))
1826 data
->may_throw
= true;
1829 case STATEMENT_LIST
:
1831 tree_stmt_iterator i
= tsi_start (t
);
1832 while (!tsi_end_p (i
))
1835 if (IS_EMPTY_STMT (t
))
1841 remove_useless_stmts_1 (tsi_stmt_ptr (i
), data
);
1844 if (TREE_CODE (t
) == STATEMENT_LIST
)
1846 tsi_link_before (&i
, t
, TSI_SAME_STMT
);
1856 data
->last_goto
= NULL
;
1860 data
->last_goto
= NULL
;
1866 remove_useless_stmts (void)
1868 struct rus_data data
;
1870 clear_special_calls ();
1874 memset (&data
, 0, sizeof (data
));
1875 remove_useless_stmts_1 (&DECL_SAVED_TREE (current_function_decl
), &data
);
1877 while (data
.repeat
);
1881 struct tree_opt_pass pass_remove_useless_stmts
=
1883 "useless", /* name */
1885 remove_useless_stmts
, /* execute */
1888 0, /* static_pass_number */
1890 PROP_gimple_any
, /* properties_required */
1891 0, /* properties_provided */
1892 0, /* properties_destroyed */
1893 0, /* todo_flags_start */
1894 TODO_dump_func
, /* todo_flags_finish */
1898 /* Remove PHI nodes associated with basic block BB and all edges out of BB. */
1901 remove_phi_nodes_and_edges_for_unreachable_block (basic_block bb
)
1905 /* Since this block is no longer reachable, we can just delete all
1906 of its PHI nodes. */
1907 phi
= phi_nodes (bb
);
1910 tree next
= PHI_CHAIN (phi
);
1911 remove_phi_node (phi
, NULL_TREE
);
1915 /* Remove edges to BB's successors. */
1916 while (EDGE_COUNT (bb
->succs
) > 0)
1917 remove_edge (EDGE_SUCC (bb
, 0));
1921 /* Remove statements of basic block BB. */
1924 remove_bb (basic_block bb
)
1926 block_stmt_iterator i
;
1927 #ifdef USE_MAPPED_LOCATION
1928 source_location loc
= UNKNOWN_LOCATION
;
1930 source_locus loc
= 0;
1935 fprintf (dump_file
, "Removing basic block %d\n", bb
->index
);
1936 if (dump_flags
& TDF_DETAILS
)
1938 dump_bb (bb
, dump_file
, 0);
1939 fprintf (dump_file
, "\n");
1943 /* If we remove the header or the latch of a loop, mark the loop for
1944 removal by setting its header and latch to NULL. */
1947 struct loop
*loop
= bb
->loop_father
;
1949 if (loop
->latch
== bb
1950 || loop
->header
== bb
)
1953 loop
->header
= NULL
;
1957 /* Remove all the instructions in the block. */
1958 for (i
= bsi_start (bb
); !bsi_end_p (i
);)
1960 tree stmt
= bsi_stmt (i
);
1961 if (TREE_CODE (stmt
) == LABEL_EXPR
1962 && FORCED_LABEL (LABEL_EXPR_LABEL (stmt
)))
1964 basic_block new_bb
= bb
->prev_bb
;
1965 block_stmt_iterator new_bsi
= bsi_start (new_bb
);
1968 bsi_insert_before (&new_bsi
, stmt
, BSI_NEW_STMT
);
1972 release_defs (stmt
);
1977 /* Don't warn for removed gotos. Gotos are often removed due to
1978 jump threading, thus resulting in bogus warnings. Not great,
1979 since this way we lose warnings for gotos in the original
1980 program that are indeed unreachable. */
1981 if (TREE_CODE (stmt
) != GOTO_EXPR
&& EXPR_HAS_LOCATION (stmt
) && !loc
)
1983 #ifdef USE_MAPPED_LOCATION
1984 if (EXPR_HAS_LOCATION (stmt
))
1985 loc
= EXPR_LOCATION (stmt
);
1988 t
= EXPR_LOCUS (stmt
);
1989 if (t
&& LOCATION_LINE (*t
) > 0)
1995 /* If requested, give a warning that the first statement in the
1996 block is unreachable. We walk statements backwards in the
1997 loop above, so the last statement we process is the first statement
1999 #ifdef USE_MAPPED_LOCATION
2000 if (loc
> BUILTINS_LOCATION
)
2001 warning (OPT_Wunreachable_code
, "%Hwill never be executed", &loc
);
2004 warning (OPT_Wunreachable_code
, "%Hwill never be executed", loc
);
2007 remove_phi_nodes_and_edges_for_unreachable_block (bb
);
2011 /* Given a basic block BB ending with COND_EXPR or SWITCH_EXPR, and a
2012 predicate VAL, return the edge that will be taken out of the block.
2013 If VAL does not match a unique edge, NULL is returned. */
2016 find_taken_edge (basic_block bb
, tree val
)
2020 stmt
= last_stmt (bb
);
2023 gcc_assert (is_ctrl_stmt (stmt
));
2026 if (! is_gimple_min_invariant (val
))
2029 if (TREE_CODE (stmt
) == COND_EXPR
)
2030 return find_taken_edge_cond_expr (bb
, val
);
2032 if (TREE_CODE (stmt
) == SWITCH_EXPR
)
2033 return find_taken_edge_switch_expr (bb
, val
);
2035 if (computed_goto_p (stmt
))
2036 return find_taken_edge_computed_goto (bb
, TREE_OPERAND( val
, 0));
2041 /* Given a constant value VAL and the entry block BB to a GOTO_EXPR
2042 statement, determine which of the outgoing edges will be taken out of the
2043 block. Return NULL if either edge may be taken. */
2046 find_taken_edge_computed_goto (basic_block bb
, tree val
)
2051 dest
= label_to_block (val
);
2054 e
= find_edge (bb
, dest
);
2055 gcc_assert (e
!= NULL
);
2061 /* Given a constant value VAL and the entry block BB to a COND_EXPR
2062 statement, determine which of the two edges will be taken out of the
2063 block. Return NULL if either edge may be taken. */
2066 find_taken_edge_cond_expr (basic_block bb
, tree val
)
2068 edge true_edge
, false_edge
;
2070 extract_true_false_edges_from_block (bb
, &true_edge
, &false_edge
);
2072 gcc_assert (TREE_CODE (val
) == INTEGER_CST
);
2073 return (zero_p (val
) ? false_edge
: true_edge
);
2076 /* Given an INTEGER_CST VAL and the entry block BB to a SWITCH_EXPR
2077 statement, determine which edge will be taken out of the block. Return
2078 NULL if any edge may be taken. */
2081 find_taken_edge_switch_expr (basic_block bb
, tree val
)
2083 tree switch_expr
, taken_case
;
2084 basic_block dest_bb
;
2087 switch_expr
= last_stmt (bb
);
2088 taken_case
= find_case_label_for_value (switch_expr
, val
);
2089 dest_bb
= label_to_block (CASE_LABEL (taken_case
));
2091 e
= find_edge (bb
, dest_bb
);
2097 /* Return the CASE_LABEL_EXPR that SWITCH_EXPR will take for VAL.
2098 We can make optimal use here of the fact that the case labels are
2099 sorted: We can do a binary search for a case matching VAL. */
2102 find_case_label_for_value (tree switch_expr
, tree val
)
2104 tree vec
= SWITCH_LABELS (switch_expr
);
2105 size_t low
, high
, n
= TREE_VEC_LENGTH (vec
);
2106 tree default_case
= TREE_VEC_ELT (vec
, n
- 1);
2108 for (low
= -1, high
= n
- 1; high
- low
> 1; )
2110 size_t i
= (high
+ low
) / 2;
2111 tree t
= TREE_VEC_ELT (vec
, i
);
2114 /* Cache the result of comparing CASE_LOW and val. */
2115 cmp
= tree_int_cst_compare (CASE_LOW (t
), val
);
2122 if (CASE_HIGH (t
) == NULL
)
2124 /* A singe-valued case label. */
2130 /* A case range. We can only handle integer ranges. */
2131 if (cmp
<= 0 && tree_int_cst_compare (CASE_HIGH (t
), val
) >= 0)
2136 return default_case
;
2142 /*---------------------------------------------------------------------------
2144 ---------------------------------------------------------------------------*/
2146 /* Dump tree-specific information of block BB to file OUTF. */
2149 tree_dump_bb (basic_block bb
, FILE *outf
, int indent
)
2151 dump_generic_bb (outf
, bb
, indent
, TDF_VOPS
);
2155 /* Dump a basic block on stderr. */
2158 debug_tree_bb (basic_block bb
)
2160 dump_bb (bb
, stderr
, 0);
2164 /* Dump basic block with index N on stderr. */
2167 debug_tree_bb_n (int n
)
2169 debug_tree_bb (BASIC_BLOCK (n
));
2170 return BASIC_BLOCK (n
);
2174 /* Dump the CFG on stderr.
2176 FLAGS are the same used by the tree dumping functions
2177 (see TDF_* in tree.h). */
2180 debug_tree_cfg (int flags
)
2182 dump_tree_cfg (stderr
, flags
);
2186 /* Dump the program showing basic block boundaries on the given FILE.
2188 FLAGS are the same used by the tree dumping functions (see TDF_* in
2192 dump_tree_cfg (FILE *file
, int flags
)
2194 if (flags
& TDF_DETAILS
)
2196 const char *funcname
2197 = lang_hooks
.decl_printable_name (current_function_decl
, 2);
2200 fprintf (file
, ";; Function %s\n\n", funcname
);
2201 fprintf (file
, ";; \n%d basic blocks, %d edges, last basic block %d.\n\n",
2202 n_basic_blocks
, n_edges
, last_basic_block
);
2204 brief_dump_cfg (file
);
2205 fprintf (file
, "\n");
2208 if (flags
& TDF_STATS
)
2209 dump_cfg_stats (file
);
2211 dump_function_to_file (current_function_decl
, file
, flags
| TDF_BLOCKS
);
2215 /* Dump CFG statistics on FILE. */
2218 dump_cfg_stats (FILE *file
)
2220 static long max_num_merged_labels
= 0;
2221 unsigned long size
, total
= 0;
2224 const char * const fmt_str
= "%-30s%-13s%12s\n";
2225 const char * const fmt_str_1
= "%-30s%13d%11lu%c\n";
2226 const char * const fmt_str_3
= "%-43s%11lu%c\n";
2227 const char *funcname
2228 = lang_hooks
.decl_printable_name (current_function_decl
, 2);
2231 fprintf (file
, "\nCFG Statistics for %s\n\n", funcname
);
2233 fprintf (file
, "---------------------------------------------------------\n");
2234 fprintf (file
, fmt_str
, "", " Number of ", "Memory");
2235 fprintf (file
, fmt_str
, "", " instances ", "used ");
2236 fprintf (file
, "---------------------------------------------------------\n");
2238 size
= n_basic_blocks
* sizeof (struct basic_block_def
);
2240 fprintf (file
, fmt_str_1
, "Basic blocks", n_basic_blocks
,
2241 SCALE (size
), LABEL (size
));
2245 num_edges
+= EDGE_COUNT (bb
->succs
);
2246 size
= num_edges
* sizeof (struct edge_def
);
2248 fprintf (file
, fmt_str_1
, "Edges", num_edges
, SCALE (size
), LABEL (size
));
2250 fprintf (file
, "---------------------------------------------------------\n");
2251 fprintf (file
, fmt_str_3
, "Total memory used by CFG data", SCALE (total
),
2253 fprintf (file
, "---------------------------------------------------------\n");
2254 fprintf (file
, "\n");
2256 if (cfg_stats
.num_merged_labels
> max_num_merged_labels
)
2257 max_num_merged_labels
= cfg_stats
.num_merged_labels
;
2259 fprintf (file
, "Coalesced label blocks: %ld (Max so far: %ld)\n",
2260 cfg_stats
.num_merged_labels
, max_num_merged_labels
);
2262 fprintf (file
, "\n");
2266 /* Dump CFG statistics on stderr. Keep extern so that it's always
2267 linked in the final executable. */
2270 debug_cfg_stats (void)
2272 dump_cfg_stats (stderr
);
2276 /* Dump the flowgraph to a .vcg FILE. */
2279 tree_cfg2vcg (FILE *file
)
2284 const char *funcname
2285 = lang_hooks
.decl_printable_name (current_function_decl
, 2);
2287 /* Write the file header. */
2288 fprintf (file
, "graph: { title: \"%s\"\n", funcname
);
2289 fprintf (file
, "node: { title: \"ENTRY\" label: \"ENTRY\" }\n");
2290 fprintf (file
, "node: { title: \"EXIT\" label: \"EXIT\" }\n");
2292 /* Write blocks and edges. */
2293 FOR_EACH_EDGE (e
, ei
, ENTRY_BLOCK_PTR
->succs
)
2295 fprintf (file
, "edge: { sourcename: \"ENTRY\" targetname: \"%d\"",
2298 if (e
->flags
& EDGE_FAKE
)
2299 fprintf (file
, " linestyle: dotted priority: 10");
2301 fprintf (file
, " linestyle: solid priority: 100");
2303 fprintf (file
, " }\n");
2309 enum tree_code head_code
, end_code
;
2310 const char *head_name
, *end_name
;
2313 tree first
= first_stmt (bb
);
2314 tree last
= last_stmt (bb
);
2318 head_code
= TREE_CODE (first
);
2319 head_name
= tree_code_name
[head_code
];
2320 head_line
= get_lineno (first
);
2323 head_name
= "no-statement";
2327 end_code
= TREE_CODE (last
);
2328 end_name
= tree_code_name
[end_code
];
2329 end_line
= get_lineno (last
);
2332 end_name
= "no-statement";
2334 fprintf (file
, "node: { title: \"%d\" label: \"#%d\\n%s (%d)\\n%s (%d)\"}\n",
2335 bb
->index
, bb
->index
, head_name
, head_line
, end_name
,
2338 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
2340 if (e
->dest
== EXIT_BLOCK_PTR
)
2341 fprintf (file
, "edge: { sourcename: \"%d\" targetname: \"EXIT\"", bb
->index
);
2343 fprintf (file
, "edge: { sourcename: \"%d\" targetname: \"%d\"", bb
->index
, e
->dest
->index
);
2345 if (e
->flags
& EDGE_FAKE
)
2346 fprintf (file
, " priority: 10 linestyle: dotted");
2348 fprintf (file
, " priority: 100 linestyle: solid");
2350 fprintf (file
, " }\n");
2353 if (bb
->next_bb
!= EXIT_BLOCK_PTR
)
2357 fputs ("}\n\n", file
);
2362 /*---------------------------------------------------------------------------
2363 Miscellaneous helpers
2364 ---------------------------------------------------------------------------*/
2366 /* Return true if T represents a stmt that always transfers control. */
2369 is_ctrl_stmt (tree t
)
2371 return (TREE_CODE (t
) == COND_EXPR
2372 || TREE_CODE (t
) == SWITCH_EXPR
2373 || TREE_CODE (t
) == GOTO_EXPR
2374 || TREE_CODE (t
) == RETURN_EXPR
2375 || TREE_CODE (t
) == RESX_EXPR
);
2379 /* Return true if T is a statement that may alter the flow of control
2380 (e.g., a call to a non-returning function). */
2383 is_ctrl_altering_stmt (tree t
)
2388 call
= get_call_expr_in (t
);
2391 /* A non-pure/const CALL_EXPR alters flow control if the current
2392 function has nonlocal labels. */
2393 if (TREE_SIDE_EFFECTS (call
) && current_function_has_nonlocal_label
)
2396 /* A CALL_EXPR also alters control flow if it does not return. */
2397 if (call_expr_flags (call
) & ECF_NORETURN
)
2401 /* If a statement can throw, it alters control flow. */
2402 return tree_can_throw_internal (t
);
2406 /* Return true if T is a computed goto. */
2409 computed_goto_p (tree t
)
2411 return (TREE_CODE (t
) == GOTO_EXPR
2412 && TREE_CODE (GOTO_DESTINATION (t
)) != LABEL_DECL
);
2416 /* Checks whether EXPR is a simple local goto. */
2419 simple_goto_p (tree expr
)
2421 return (TREE_CODE (expr
) == GOTO_EXPR
2422 && TREE_CODE (GOTO_DESTINATION (expr
)) == LABEL_DECL
);
2426 /* Return true if T should start a new basic block. PREV_T is the
2427 statement preceding T. It is used when T is a label or a case label.
2428 Labels should only start a new basic block if their previous statement
2429 wasn't a label. Otherwise, sequence of labels would generate
2430 unnecessary basic blocks that only contain a single label. */
2433 stmt_starts_bb_p (tree t
, tree prev_t
)
2438 /* LABEL_EXPRs start a new basic block only if the preceding
2439 statement wasn't a label of the same type. This prevents the
2440 creation of consecutive blocks that have nothing but a single
2442 if (TREE_CODE (t
) == LABEL_EXPR
)
2444 /* Nonlocal and computed GOTO targets always start a new block. */
2445 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (t
))
2446 || FORCED_LABEL (LABEL_EXPR_LABEL (t
)))
2449 if (prev_t
&& TREE_CODE (prev_t
) == LABEL_EXPR
)
2451 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (prev_t
)))
2454 cfg_stats
.num_merged_labels
++;
2465 /* Return true if T should end a basic block. */
2468 stmt_ends_bb_p (tree t
)
2470 return is_ctrl_stmt (t
) || is_ctrl_altering_stmt (t
);
2474 /* Add gotos that used to be represented implicitly in the CFG. */
2477 disband_implicit_edges (void)
2480 block_stmt_iterator last
;
2487 last
= bsi_last (bb
);
2488 stmt
= last_stmt (bb
);
2490 if (stmt
&& TREE_CODE (stmt
) == COND_EXPR
)
2492 /* Remove superfluous gotos from COND_EXPR branches. Moved
2493 from cfg_remove_useless_stmts here since it violates the
2494 invariants for tree--cfg correspondence and thus fits better
2495 here where we do it anyway. */
2496 e
= find_edge (bb
, bb
->next_bb
);
2499 if (e
->flags
& EDGE_TRUE_VALUE
)
2500 COND_EXPR_THEN (stmt
) = build_empty_stmt ();
2501 else if (e
->flags
& EDGE_FALSE_VALUE
)
2502 COND_EXPR_ELSE (stmt
) = build_empty_stmt ();
2505 e
->flags
|= EDGE_FALLTHRU
;
2511 if (stmt
&& TREE_CODE (stmt
) == RETURN_EXPR
)
2513 /* Remove the RETURN_EXPR if we may fall though to the exit
2515 gcc_assert (single_succ_p (bb
));
2516 gcc_assert (single_succ (bb
) == EXIT_BLOCK_PTR
);
2518 if (bb
->next_bb
== EXIT_BLOCK_PTR
2519 && !TREE_OPERAND (stmt
, 0))
2522 single_succ_edge (bb
)->flags
|= EDGE_FALLTHRU
;
2527 /* There can be no fallthru edge if the last statement is a control
2529 if (stmt
&& is_ctrl_stmt (stmt
))
2532 /* Find a fallthru edge and emit the goto if necessary. */
2533 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
2534 if (e
->flags
& EDGE_FALLTHRU
)
2537 if (!e
|| e
->dest
== bb
->next_bb
)
2540 gcc_assert (e
->dest
!= EXIT_BLOCK_PTR
);
2541 label
= tree_block_label (e
->dest
);
2543 stmt
= build1 (GOTO_EXPR
, void_type_node
, label
);
2544 #ifdef USE_MAPPED_LOCATION
2545 SET_EXPR_LOCATION (stmt
, e
->goto_locus
);
2547 SET_EXPR_LOCUS (stmt
, e
->goto_locus
);
2549 bsi_insert_after (&last
, stmt
, BSI_NEW_STMT
);
2550 e
->flags
&= ~EDGE_FALLTHRU
;
2554 /* Remove block annotations and other datastructures. */
2557 delete_tree_cfg_annotations (void)
2561 label_to_block_map
= NULL
;
2567 /* Return the first statement in basic block BB. */
2570 first_stmt (basic_block bb
)
2572 block_stmt_iterator i
= bsi_start (bb
);
2573 return !bsi_end_p (i
) ? bsi_stmt (i
) : NULL_TREE
;
2577 /* Return the last statement in basic block BB. */
2580 last_stmt (basic_block bb
)
2582 block_stmt_iterator b
= bsi_last (bb
);
2583 return !bsi_end_p (b
) ? bsi_stmt (b
) : NULL_TREE
;
2587 /* Return a pointer to the last statement in block BB. */
2590 last_stmt_ptr (basic_block bb
)
2592 block_stmt_iterator last
= bsi_last (bb
);
2593 return !bsi_end_p (last
) ? bsi_stmt_ptr (last
) : NULL
;
2597 /* Return the last statement of an otherwise empty block. Return NULL
2598 if the block is totally empty, or if it contains more than one
2602 last_and_only_stmt (basic_block bb
)
2604 block_stmt_iterator i
= bsi_last (bb
);
2610 last
= bsi_stmt (i
);
2615 /* Empty statements should no longer appear in the instruction stream.
2616 Everything that might have appeared before should be deleted by
2617 remove_useless_stmts, and the optimizers should just bsi_remove
2618 instead of smashing with build_empty_stmt.
2620 Thus the only thing that should appear here in a block containing
2621 one executable statement is a label. */
2622 prev
= bsi_stmt (i
);
2623 if (TREE_CODE (prev
) == LABEL_EXPR
)
2630 /* Mark BB as the basic block holding statement T. */
2633 set_bb_for_stmt (tree t
, basic_block bb
)
2635 if (TREE_CODE (t
) == PHI_NODE
)
2637 else if (TREE_CODE (t
) == STATEMENT_LIST
)
2639 tree_stmt_iterator i
;
2640 for (i
= tsi_start (t
); !tsi_end_p (i
); tsi_next (&i
))
2641 set_bb_for_stmt (tsi_stmt (i
), bb
);
2645 stmt_ann_t ann
= get_stmt_ann (t
);
2648 /* If the statement is a label, add the label to block-to-labels map
2649 so that we can speed up edge creation for GOTO_EXPRs. */
2650 if (TREE_CODE (t
) == LABEL_EXPR
)
2654 t
= LABEL_EXPR_LABEL (t
);
2655 uid
= LABEL_DECL_UID (t
);
2658 LABEL_DECL_UID (t
) = uid
= cfun
->last_label_uid
++;
2659 if (VARRAY_SIZE (label_to_block_map
) <= (unsigned) uid
)
2660 VARRAY_GROW (label_to_block_map
, 3 * uid
/ 2);
2663 /* We're moving an existing label. Make sure that we've
2664 removed it from the old block. */
2665 gcc_assert (!bb
|| !VARRAY_BB (label_to_block_map
, uid
));
2666 VARRAY_BB (label_to_block_map
, uid
) = bb
;
2671 /* Finds iterator for STMT. */
2673 extern block_stmt_iterator
2674 bsi_for_stmt (tree stmt
)
2676 block_stmt_iterator bsi
;
2678 for (bsi
= bsi_start (bb_for_stmt (stmt
)); !bsi_end_p (bsi
); bsi_next (&bsi
))
2679 if (bsi_stmt (bsi
) == stmt
)
2685 /* Mark statement T as modified, and update it. */
2687 update_modified_stmts (tree t
)
2689 if (TREE_CODE (t
) == STATEMENT_LIST
)
2691 tree_stmt_iterator i
;
2693 for (i
= tsi_start (t
); !tsi_end_p (i
); tsi_next (&i
))
2695 stmt
= tsi_stmt (i
);
2696 update_stmt_if_modified (stmt
);
2700 update_stmt_if_modified (t
);
2703 /* Insert statement (or statement list) T before the statement
2704 pointed-to by iterator I. M specifies how to update iterator I
2705 after insertion (see enum bsi_iterator_update). */
2708 bsi_insert_before (block_stmt_iterator
*i
, tree t
, enum bsi_iterator_update m
)
2710 set_bb_for_stmt (t
, i
->bb
);
2711 update_modified_stmts (t
);
2712 tsi_link_before (&i
->tsi
, t
, m
);
2716 /* Insert statement (or statement list) T after the statement
2717 pointed-to by iterator I. M specifies how to update iterator I
2718 after insertion (see enum bsi_iterator_update). */
2721 bsi_insert_after (block_stmt_iterator
*i
, tree t
, enum bsi_iterator_update m
)
2723 set_bb_for_stmt (t
, i
->bb
);
2724 update_modified_stmts (t
);
2725 tsi_link_after (&i
->tsi
, t
, m
);
2729 /* Remove the statement pointed to by iterator I. The iterator is updated
2730 to the next statement. */
2733 bsi_remove (block_stmt_iterator
*i
)
2735 tree t
= bsi_stmt (*i
);
2736 set_bb_for_stmt (t
, NULL
);
2737 delink_stmt_imm_use (t
);
2738 tsi_delink (&i
->tsi
);
2739 mark_stmt_modified (t
);
2743 /* Move the statement at FROM so it comes right after the statement at TO. */
2746 bsi_move_after (block_stmt_iterator
*from
, block_stmt_iterator
*to
)
2748 tree stmt
= bsi_stmt (*from
);
2750 bsi_insert_after (to
, stmt
, BSI_SAME_STMT
);
2754 /* Move the statement at FROM so it comes right before the statement at TO. */
2757 bsi_move_before (block_stmt_iterator
*from
, block_stmt_iterator
*to
)
2759 tree stmt
= bsi_stmt (*from
);
2761 bsi_insert_before (to
, stmt
, BSI_SAME_STMT
);
2765 /* Move the statement at FROM to the end of basic block BB. */
2768 bsi_move_to_bb_end (block_stmt_iterator
*from
, basic_block bb
)
2770 block_stmt_iterator last
= bsi_last (bb
);
2772 /* Have to check bsi_end_p because it could be an empty block. */
2773 if (!bsi_end_p (last
) && is_ctrl_stmt (bsi_stmt (last
)))
2774 bsi_move_before (from
, &last
);
2776 bsi_move_after (from
, &last
);
2780 /* Replace the contents of the statement pointed to by iterator BSI
2781 with STMT. If PRESERVE_EH_INFO is true, the exception handling
2782 information of the original statement is preserved. */
2785 bsi_replace (const block_stmt_iterator
*bsi
, tree stmt
, bool preserve_eh_info
)
2788 tree orig_stmt
= bsi_stmt (*bsi
);
2790 SET_EXPR_LOCUS (stmt
, EXPR_LOCUS (orig_stmt
));
2791 set_bb_for_stmt (stmt
, bsi
->bb
);
2793 /* Preserve EH region information from the original statement, if
2794 requested by the caller. */
2795 if (preserve_eh_info
)
2797 eh_region
= lookup_stmt_eh_region (orig_stmt
);
2799 add_stmt_to_eh_region (stmt
, eh_region
);
2802 delink_stmt_imm_use (orig_stmt
);
2803 *bsi_stmt_ptr (*bsi
) = stmt
;
2804 mark_stmt_modified (stmt
);
2805 update_modified_stmts (stmt
);
2809 /* Insert the statement pointed-to by BSI into edge E. Every attempt
2810 is made to place the statement in an existing basic block, but
2811 sometimes that isn't possible. When it isn't possible, the edge is
2812 split and the statement is added to the new block.
2814 In all cases, the returned *BSI points to the correct location. The
2815 return value is true if insertion should be done after the location,
2816 or false if it should be done before the location. If new basic block
2817 has to be created, it is stored in *NEW_BB. */
2820 tree_find_edge_insert_loc (edge e
, block_stmt_iterator
*bsi
,
2821 basic_block
*new_bb
)
2823 basic_block dest
, src
;
2829 /* If the destination has one predecessor which has no PHI nodes,
2830 insert there. Except for the exit block.
2832 The requirement for no PHI nodes could be relaxed. Basically we
2833 would have to examine the PHIs to prove that none of them used
2834 the value set by the statement we want to insert on E. That
2835 hardly seems worth the effort. */
2836 if (single_pred_p (dest
)
2837 && ! phi_nodes (dest
)
2838 && dest
!= EXIT_BLOCK_PTR
)
2840 *bsi
= bsi_start (dest
);
2841 if (bsi_end_p (*bsi
))
2844 /* Make sure we insert after any leading labels. */
2845 tmp
= bsi_stmt (*bsi
);
2846 while (TREE_CODE (tmp
) == LABEL_EXPR
)
2849 if (bsi_end_p (*bsi
))
2851 tmp
= bsi_stmt (*bsi
);
2854 if (bsi_end_p (*bsi
))
2856 *bsi
= bsi_last (dest
);
2863 /* If the source has one successor, the edge is not abnormal and
2864 the last statement does not end a basic block, insert there.
2865 Except for the entry block. */
2867 if ((e
->flags
& EDGE_ABNORMAL
) == 0
2868 && single_succ_p (src
)
2869 && src
!= ENTRY_BLOCK_PTR
)
2871 *bsi
= bsi_last (src
);
2872 if (bsi_end_p (*bsi
))
2875 tmp
= bsi_stmt (*bsi
);
2876 if (!stmt_ends_bb_p (tmp
))
2879 /* Insert code just before returning the value. We may need to decompose
2880 the return in the case it contains non-trivial operand. */
2881 if (TREE_CODE (tmp
) == RETURN_EXPR
)
2883 tree op
= TREE_OPERAND (tmp
, 0);
2884 if (!is_gimple_val (op
))
2886 gcc_assert (TREE_CODE (op
) == MODIFY_EXPR
);
2887 bsi_insert_before (bsi
, op
, BSI_NEW_STMT
);
2888 TREE_OPERAND (tmp
, 0) = TREE_OPERAND (op
, 0);
2895 /* Otherwise, create a new basic block, and split this edge. */
2896 dest
= split_edge (e
);
2899 e
= single_pred_edge (dest
);
2904 /* This routine will commit all pending edge insertions, creating any new
2905 basic blocks which are necessary. */
2908 bsi_commit_edge_inserts (void)
2914 bsi_commit_one_edge_insert (single_succ_edge (ENTRY_BLOCK_PTR
), NULL
);
2917 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
2918 bsi_commit_one_edge_insert (e
, NULL
);
2922 /* Commit insertions pending at edge E. If a new block is created, set NEW_BB
2923 to this block, otherwise set it to NULL. */
2926 bsi_commit_one_edge_insert (edge e
, basic_block
*new_bb
)
2930 if (PENDING_STMT (e
))
2932 block_stmt_iterator bsi
;
2933 tree stmt
= PENDING_STMT (e
);
2935 PENDING_STMT (e
) = NULL_TREE
;
2937 if (tree_find_edge_insert_loc (e
, &bsi
, new_bb
))
2938 bsi_insert_after (&bsi
, stmt
, BSI_NEW_STMT
);
2940 bsi_insert_before (&bsi
, stmt
, BSI_NEW_STMT
);
2945 /* Add STMT to the pending list of edge E. No actual insertion is
2946 made until a call to bsi_commit_edge_inserts () is made. */
2949 bsi_insert_on_edge (edge e
, tree stmt
)
2951 append_to_statement_list (stmt
, &PENDING_STMT (e
));
2954 /* Similar to bsi_insert_on_edge+bsi_commit_edge_inserts. If a new
2955 block has to be created, it is returned. */
2958 bsi_insert_on_edge_immediate (edge e
, tree stmt
)
2960 block_stmt_iterator bsi
;
2961 basic_block new_bb
= NULL
;
2963 gcc_assert (!PENDING_STMT (e
));
2965 if (tree_find_edge_insert_loc (e
, &bsi
, &new_bb
))
2966 bsi_insert_after (&bsi
, stmt
, BSI_NEW_STMT
);
2968 bsi_insert_before (&bsi
, stmt
, BSI_NEW_STMT
);
2973 /*---------------------------------------------------------------------------
2974 Tree specific functions for CFG manipulation
2975 ---------------------------------------------------------------------------*/
2977 /* Reinstall those PHI arguments queued in OLD_EDGE to NEW_EDGE. */
2980 reinstall_phi_args (edge new_edge
, edge old_edge
)
2984 if (!PENDING_STMT (old_edge
))
2987 for (var
= PENDING_STMT (old_edge
), phi
= phi_nodes (new_edge
->dest
);
2989 var
= TREE_CHAIN (var
), phi
= PHI_CHAIN (phi
))
2991 tree result
= TREE_PURPOSE (var
);
2992 tree arg
= TREE_VALUE (var
);
2994 gcc_assert (result
== PHI_RESULT (phi
));
2996 add_phi_arg (phi
, arg
, new_edge
);
2999 PENDING_STMT (old_edge
) = NULL
;
3002 /* Split a (typically critical) edge EDGE_IN. Return the new block.
3003 Abort on abnormal edges. */
3006 tree_split_edge (edge edge_in
)
3008 basic_block new_bb
, after_bb
, dest
, src
;
3011 /* Abnormal edges cannot be split. */
3012 gcc_assert (!(edge_in
->flags
& EDGE_ABNORMAL
));
3015 dest
= edge_in
->dest
;
3017 /* Place the new block in the block list. Try to keep the new block
3018 near its "logical" location. This is of most help to humans looking
3019 at debugging dumps. */
3020 if (dest
->prev_bb
&& find_edge (dest
->prev_bb
, dest
))
3021 after_bb
= edge_in
->src
;
3023 after_bb
= dest
->prev_bb
;
3025 new_bb
= create_empty_bb (after_bb
);
3026 new_bb
->frequency
= EDGE_FREQUENCY (edge_in
);
3027 new_bb
->count
= edge_in
->count
;
3028 new_edge
= make_edge (new_bb
, dest
, EDGE_FALLTHRU
);
3029 new_edge
->probability
= REG_BR_PROB_BASE
;
3030 new_edge
->count
= edge_in
->count
;
3032 e
= redirect_edge_and_branch (edge_in
, new_bb
);
3034 reinstall_phi_args (new_edge
, e
);
3040 /* Return true when BB has label LABEL in it. */
3043 has_label_p (basic_block bb
, tree label
)
3045 block_stmt_iterator bsi
;
3047 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
3049 tree stmt
= bsi_stmt (bsi
);
3051 if (TREE_CODE (stmt
) != LABEL_EXPR
)
3053 if (LABEL_EXPR_LABEL (stmt
) == label
)
3060 /* Callback for walk_tree, check that all elements with address taken are
3061 properly noticed as such. The DATA is an int* that is 1 if TP was seen
3062 inside a PHI node. */
3065 verify_expr (tree
*tp
, int *walk_subtrees
, void *data ATTRIBUTE_UNUSED
)
3068 bool in_phi
= (data
!= NULL
);
3073 /* Check operand N for being valid GIMPLE and give error MSG if not.
3074 We check for constants explicitly since they are not considered
3075 gimple invariants if they overflowed. */
3076 #define CHECK_OP(N, MSG) \
3077 do { if (!CONSTANT_CLASS_P (TREE_OPERAND (t, N)) \
3078 && !is_gimple_val (TREE_OPERAND (t, N))) \
3079 { error (MSG); return TREE_OPERAND (t, N); }} while (0)
3081 switch (TREE_CODE (t
))
3084 if (SSA_NAME_IN_FREE_LIST (t
))
3086 error ("SSA name in freelist but still referenced");
3092 x
= fold (ASSERT_EXPR_COND (t
));
3093 if (x
== boolean_false_node
)
3095 error ("ASSERT_EXPR with an always-false condition");
3101 x
= TREE_OPERAND (t
, 0);
3102 if (TREE_CODE (x
) == BIT_FIELD_REF
3103 && is_gimple_reg (TREE_OPERAND (x
, 0)))
3105 error ("GIMPLE register modified with BIT_FIELD_REF");
3114 bool old_side_effects
;
3117 bool new_side_effects
;
3119 /* ??? tree-ssa-alias.c may have overlooked dead PHI nodes, missing
3120 dead PHIs that take the address of something. But if the PHI
3121 result is dead, the fact that it takes the address of anything
3122 is irrelevant. Because we can not tell from here if a PHI result
3123 is dead, we just skip this check for PHIs altogether. This means
3124 we may be missing "valid" checks, but what can you do?
3125 This was PR19217. */
3129 old_invariant
= TREE_INVARIANT (t
);
3130 old_constant
= TREE_CONSTANT (t
);
3131 old_side_effects
= TREE_SIDE_EFFECTS (t
);
3133 recompute_tree_invarant_for_addr_expr (t
);
3134 new_invariant
= TREE_INVARIANT (t
);
3135 new_side_effects
= TREE_SIDE_EFFECTS (t
);
3136 new_constant
= TREE_CONSTANT (t
);
3138 if (old_invariant
!= new_invariant
)
3140 error ("invariant not recomputed when ADDR_EXPR changed");
3144 if (old_constant
!= new_constant
)
3146 error ("constant not recomputed when ADDR_EXPR changed");
3149 if (old_side_effects
!= new_side_effects
)
3151 error ("side effects not recomputed when ADDR_EXPR changed");
3155 /* Skip any references (they will be checked when we recurse down the
3156 tree) and ensure that any variable used as a prefix is marked
3158 for (x
= TREE_OPERAND (t
, 0);
3159 handled_component_p (x
);
3160 x
= TREE_OPERAND (x
, 0))
3163 if (TREE_CODE (x
) != VAR_DECL
&& TREE_CODE (x
) != PARM_DECL
)
3165 if (!TREE_ADDRESSABLE (x
))
3167 error ("address taken, but ADDRESSABLE bit not set");
3174 x
= COND_EXPR_COND (t
);
3175 if (TREE_CODE (TREE_TYPE (x
)) != BOOLEAN_TYPE
)
3177 error ("non-boolean used in condition");
3180 if (!is_gimple_condexpr (x
))
3182 error ("Invalid conditional operand");
3189 case FIX_TRUNC_EXPR
:
3191 case FIX_FLOOR_EXPR
:
3192 case FIX_ROUND_EXPR
:
3197 case NON_LVALUE_EXPR
:
3198 case TRUTH_NOT_EXPR
:
3199 CHECK_OP (0, "Invalid operand to unary operator");
3206 case ARRAY_RANGE_REF
:
3208 case VIEW_CONVERT_EXPR
:
3209 /* We have a nest of references. Verify that each of the operands
3210 that determine where to reference is either a constant or a variable,
3211 verify that the base is valid, and then show we've already checked
3213 while (handled_component_p (t
))
3215 if (TREE_CODE (t
) == COMPONENT_REF
&& TREE_OPERAND (t
, 2))
3216 CHECK_OP (2, "Invalid COMPONENT_REF offset operator");
3217 else if (TREE_CODE (t
) == ARRAY_REF
3218 || TREE_CODE (t
) == ARRAY_RANGE_REF
)
3220 CHECK_OP (1, "Invalid array index.");
3221 if (TREE_OPERAND (t
, 2))
3222 CHECK_OP (2, "Invalid array lower bound.");
3223 if (TREE_OPERAND (t
, 3))
3224 CHECK_OP (3, "Invalid array stride.");
3226 else if (TREE_CODE (t
) == BIT_FIELD_REF
)
3228 CHECK_OP (1, "Invalid operand to BIT_FIELD_REF");
3229 CHECK_OP (2, "Invalid operand to BIT_FIELD_REF");
3232 t
= TREE_OPERAND (t
, 0);
3235 if (!CONSTANT_CLASS_P (t
) && !is_gimple_lvalue (t
))
3237 error ("Invalid reference prefix.");
3249 case UNORDERED_EXPR
:
3260 case TRUNC_DIV_EXPR
:
3262 case FLOOR_DIV_EXPR
:
3263 case ROUND_DIV_EXPR
:
3264 case TRUNC_MOD_EXPR
:
3266 case FLOOR_MOD_EXPR
:
3267 case ROUND_MOD_EXPR
:
3269 case EXACT_DIV_EXPR
:
3279 CHECK_OP (0, "Invalid operand to binary operator");
3280 CHECK_OP (1, "Invalid operand to binary operator");
3292 /* Verify STMT, return true if STMT is not in GIMPLE form.
3293 TODO: Implement type checking. */
3296 verify_stmt (tree stmt
, bool last_in_block
)
3300 if (!is_gimple_stmt (stmt
))
3302 error ("Is not a valid GIMPLE statement.");
3306 addr
= walk_tree (&stmt
, verify_expr
, NULL
, NULL
);
3309 debug_generic_stmt (addr
);
3313 /* If the statement is marked as part of an EH region, then it is
3314 expected that the statement could throw. Verify that when we
3315 have optimizations that simplify statements such that we prove
3316 that they cannot throw, that we update other data structures
3318 if (lookup_stmt_eh_region (stmt
) >= 0)
3320 if (!tree_could_throw_p (stmt
))
3322 error ("Statement marked for throw, but doesn%'t.");
3325 if (!last_in_block
&& tree_can_throw_internal (stmt
))
3327 error ("Statement marked for throw in middle of block.");
3335 debug_generic_stmt (stmt
);
3340 /* Return true when the T can be shared. */
3343 tree_node_can_be_shared (tree t
)
3345 if (IS_TYPE_OR_DECL_P (t
)
3346 /* We check for constants explicitly since they are not considered
3347 gimple invariants if they overflowed. */
3348 || CONSTANT_CLASS_P (t
)
3349 || is_gimple_min_invariant (t
)
3350 || TREE_CODE (t
) == SSA_NAME
3351 || t
== error_mark_node
)
3354 if (TREE_CODE (t
) == CASE_LABEL_EXPR
)
3357 while (((TREE_CODE (t
) == ARRAY_REF
|| TREE_CODE (t
) == ARRAY_RANGE_REF
)
3358 /* We check for constants explicitly since they are not considered
3359 gimple invariants if they overflowed. */
3360 && (CONSTANT_CLASS_P (TREE_OPERAND (t
, 1))
3361 || is_gimple_min_invariant (TREE_OPERAND (t
, 1))))
3362 || (TREE_CODE (t
) == COMPONENT_REF
3363 || TREE_CODE (t
) == REALPART_EXPR
3364 || TREE_CODE (t
) == IMAGPART_EXPR
))
3365 t
= TREE_OPERAND (t
, 0);
3374 /* Called via walk_trees. Verify tree sharing. */
3377 verify_node_sharing (tree
* tp
, int *walk_subtrees
, void *data
)
3379 htab_t htab
= (htab_t
) data
;
3382 if (tree_node_can_be_shared (*tp
))
3384 *walk_subtrees
= false;
3388 slot
= htab_find_slot (htab
, *tp
, INSERT
);
3397 /* Verify the GIMPLE statement chain. */
3403 block_stmt_iterator bsi
;
3408 timevar_push (TV_TREE_STMT_VERIFY
);
3409 htab
= htab_create (37, htab_hash_pointer
, htab_eq_pointer
, NULL
);
3416 for (phi
= phi_nodes (bb
); phi
; phi
= PHI_CHAIN (phi
))
3418 int phi_num_args
= PHI_NUM_ARGS (phi
);
3420 if (bb_for_stmt (phi
) != bb
)
3422 error ("bb_for_stmt (phi) is set to a wrong basic block\n");
3426 for (i
= 0; i
< phi_num_args
; i
++)
3428 tree t
= PHI_ARG_DEF (phi
, i
);
3431 /* Addressable variables do have SSA_NAMEs but they
3432 are not considered gimple values. */
3433 if (TREE_CODE (t
) != SSA_NAME
3434 && TREE_CODE (t
) != FUNCTION_DECL
3435 && !is_gimple_val (t
))
3437 error ("PHI def is not a GIMPLE value");
3438 debug_generic_stmt (phi
);
3439 debug_generic_stmt (t
);
3443 addr
= walk_tree (&t
, verify_expr
, (void *) 1, NULL
);
3446 debug_generic_stmt (addr
);
3450 addr
= walk_tree (&t
, verify_node_sharing
, htab
, NULL
);
3453 error ("Incorrect sharing of tree nodes");
3454 debug_generic_stmt (phi
);
3455 debug_generic_stmt (addr
);
3461 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); )
3463 tree stmt
= bsi_stmt (bsi
);
3465 if (bb_for_stmt (stmt
) != bb
)
3467 error ("bb_for_stmt (stmt) is set to a wrong basic block\n");
3472 err
|= verify_stmt (stmt
, bsi_end_p (bsi
));
3473 addr
= walk_tree (&stmt
, verify_node_sharing
, htab
, NULL
);
3476 error ("Incorrect sharing of tree nodes");
3477 debug_generic_stmt (stmt
);
3478 debug_generic_stmt (addr
);
3485 internal_error ("verify_stmts failed.");
3488 timevar_pop (TV_TREE_STMT_VERIFY
);
3492 /* Verifies that the flow information is OK. */
3495 tree_verify_flow_info (void)
3499 block_stmt_iterator bsi
;
3504 if (ENTRY_BLOCK_PTR
->stmt_list
)
3506 error ("ENTRY_BLOCK has a statement list associated with it\n");
3510 if (EXIT_BLOCK_PTR
->stmt_list
)
3512 error ("EXIT_BLOCK has a statement list associated with it\n");
3516 FOR_EACH_EDGE (e
, ei
, EXIT_BLOCK_PTR
->preds
)
3517 if (e
->flags
& EDGE_FALLTHRU
)
3519 error ("Fallthru to exit from bb %d\n", e
->src
->index
);
3525 bool found_ctrl_stmt
= false;
3529 /* Skip labels on the start of basic block. */
3530 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
3532 tree prev_stmt
= stmt
;
3534 stmt
= bsi_stmt (bsi
);
3536 if (TREE_CODE (stmt
) != LABEL_EXPR
)
3539 if (prev_stmt
&& DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt
)))
3541 error ("Nonlocal label %s is not first "
3542 "in a sequence of labels in bb %d",
3543 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt
))),
3548 if (label_to_block (LABEL_EXPR_LABEL (stmt
)) != bb
)
3550 error ("Label %s to block does not match in bb %d\n",
3551 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt
))),
3556 if (decl_function_context (LABEL_EXPR_LABEL (stmt
))
3557 != current_function_decl
)
3559 error ("Label %s has incorrect context in bb %d\n",
3560 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt
))),
3566 /* Verify that body of basic block BB is free of control flow. */
3567 for (; !bsi_end_p (bsi
); bsi_next (&bsi
))
3569 tree stmt
= bsi_stmt (bsi
);
3571 if (found_ctrl_stmt
)
3573 error ("Control flow in the middle of basic block %d\n",
3578 if (stmt_ends_bb_p (stmt
))
3579 found_ctrl_stmt
= true;
3581 if (TREE_CODE (stmt
) == LABEL_EXPR
)
3583 error ("Label %s in the middle of basic block %d\n",
3584 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt
))),
3589 bsi
= bsi_last (bb
);
3590 if (bsi_end_p (bsi
))
3593 stmt
= bsi_stmt (bsi
);
3595 err
|= verify_eh_edges (stmt
);
3597 if (is_ctrl_stmt (stmt
))
3599 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
3600 if (e
->flags
& EDGE_FALLTHRU
)
3602 error ("Fallthru edge after a control statement in bb %d \n",
3608 switch (TREE_CODE (stmt
))
3614 if (TREE_CODE (COND_EXPR_THEN (stmt
)) != GOTO_EXPR
3615 || TREE_CODE (COND_EXPR_ELSE (stmt
)) != GOTO_EXPR
)
3617 error ("Structured COND_EXPR at the end of bb %d\n", bb
->index
);
3621 extract_true_false_edges_from_block (bb
, &true_edge
, &false_edge
);
3623 if (!true_edge
|| !false_edge
3624 || !(true_edge
->flags
& EDGE_TRUE_VALUE
)
3625 || !(false_edge
->flags
& EDGE_FALSE_VALUE
)
3626 || (true_edge
->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
))
3627 || (false_edge
->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
))
3628 || EDGE_COUNT (bb
->succs
) >= 3)
3630 error ("Wrong outgoing edge flags at end of bb %d\n",
3635 if (!has_label_p (true_edge
->dest
,
3636 GOTO_DESTINATION (COND_EXPR_THEN (stmt
))))
3638 error ("%<then%> label does not match edge at end of bb %d\n",
3643 if (!has_label_p (false_edge
->dest
,
3644 GOTO_DESTINATION (COND_EXPR_ELSE (stmt
))))
3646 error ("%<else%> label does not match edge at end of bb %d\n",
3654 if (simple_goto_p (stmt
))
3656 error ("Explicit goto at end of bb %d\n", bb
->index
);
3661 /* FIXME. We should double check that the labels in the
3662 destination blocks have their address taken. */
3663 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
3664 if ((e
->flags
& (EDGE_FALLTHRU
| EDGE_TRUE_VALUE
3665 | EDGE_FALSE_VALUE
))
3666 || !(e
->flags
& EDGE_ABNORMAL
))
3668 error ("Wrong outgoing edge flags at end of bb %d\n",
3676 if (!single_succ_p (bb
)
3677 || (single_succ_edge (bb
)->flags
3678 & (EDGE_FALLTHRU
| EDGE_ABNORMAL
3679 | EDGE_TRUE_VALUE
| EDGE_FALSE_VALUE
)))
3681 error ("Wrong outgoing edge flags at end of bb %d\n", bb
->index
);
3684 if (single_succ (bb
) != EXIT_BLOCK_PTR
)
3686 error ("Return edge does not point to exit in bb %d\n",
3699 vec
= SWITCH_LABELS (stmt
);
3700 n
= TREE_VEC_LENGTH (vec
);
3702 /* Mark all the destination basic blocks. */
3703 for (i
= 0; i
< n
; ++i
)
3705 tree lab
= CASE_LABEL (TREE_VEC_ELT (vec
, i
));
3706 basic_block label_bb
= label_to_block (lab
);
3708 gcc_assert (!label_bb
->aux
|| label_bb
->aux
== (void *)1);
3709 label_bb
->aux
= (void *)1;
3712 /* Verify that the case labels are sorted. */
3713 prev
= TREE_VEC_ELT (vec
, 0);
3714 for (i
= 1; i
< n
- 1; ++i
)
3716 tree c
= TREE_VEC_ELT (vec
, i
);
3719 error ("Found default case not at end of case vector");
3723 if (! tree_int_cst_lt (CASE_LOW (prev
), CASE_LOW (c
)))
3725 error ("Case labels not sorted:\n ");
3726 print_generic_expr (stderr
, prev
, 0);
3727 fprintf (stderr
," is greater than ");
3728 print_generic_expr (stderr
, c
, 0);
3729 fprintf (stderr
," but comes before it.\n");
3734 if (CASE_LOW (TREE_VEC_ELT (vec
, n
- 1)))
3736 error ("No default case found at end of case vector");
3740 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
3744 error ("Extra outgoing edge %d->%d\n",
3745 bb
->index
, e
->dest
->index
);
3748 e
->dest
->aux
= (void *)2;
3749 if ((e
->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
3750 | EDGE_TRUE_VALUE
| EDGE_FALSE_VALUE
)))
3752 error ("Wrong outgoing edge flags at end of bb %d\n",
3758 /* Check that we have all of them. */
3759 for (i
= 0; i
< n
; ++i
)
3761 tree lab
= CASE_LABEL (TREE_VEC_ELT (vec
, i
));
3762 basic_block label_bb
= label_to_block (lab
);
3764 if (label_bb
->aux
!= (void *)2)
3766 error ("Missing edge %i->%i",
3767 bb
->index
, label_bb
->index
);
3772 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
3773 e
->dest
->aux
= (void *)0;
3780 if (dom_computed
[CDI_DOMINATORS
] >= DOM_NO_FAST_QUERY
)
3781 verify_dominators (CDI_DOMINATORS
);
3787 /* Updates phi nodes after creating a forwarder block joined
3788 by edge FALLTHRU. */
3791 tree_make_forwarder_block (edge fallthru
)
3795 basic_block dummy
, bb
;
3796 tree phi
, new_phi
, var
;
3798 dummy
= fallthru
->src
;
3799 bb
= fallthru
->dest
;
3801 if (single_pred_p (bb
))
3804 /* If we redirected a branch we must create new phi nodes at the
3806 for (phi
= phi_nodes (dummy
); phi
; phi
= PHI_CHAIN (phi
))
3808 var
= PHI_RESULT (phi
);
3809 new_phi
= create_phi_node (var
, bb
);
3810 SSA_NAME_DEF_STMT (var
) = new_phi
;
3811 SET_PHI_RESULT (phi
, make_ssa_name (SSA_NAME_VAR (var
), phi
));
3812 add_phi_arg (new_phi
, PHI_RESULT (phi
), fallthru
);
3815 /* Ensure that the PHI node chain is in the same order. */
3816 set_phi_nodes (bb
, phi_reverse (phi_nodes (bb
)));
3818 /* Add the arguments we have stored on edges. */
3819 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
3824 flush_pending_stmts (e
);
3829 /* Return a non-special label in the head of basic block BLOCK.
3830 Create one if it doesn't exist. */
3833 tree_block_label (basic_block bb
)
3835 block_stmt_iterator i
, s
= bsi_start (bb
);
3839 for (i
= s
; !bsi_end_p (i
); first
= false, bsi_next (&i
))
3841 stmt
= bsi_stmt (i
);
3842 if (TREE_CODE (stmt
) != LABEL_EXPR
)
3844 label
= LABEL_EXPR_LABEL (stmt
);
3845 if (!DECL_NONLOCAL (label
))
3848 bsi_move_before (&i
, &s
);
3853 label
= create_artificial_label ();
3854 stmt
= build1 (LABEL_EXPR
, void_type_node
, label
);
3855 bsi_insert_before (&s
, stmt
, BSI_NEW_STMT
);
3860 /* Attempt to perform edge redirection by replacing a possibly complex
3861 jump instruction by a goto or by removing the jump completely.
3862 This can apply only if all edges now point to the same block. The
3863 parameters and return values are equivalent to
3864 redirect_edge_and_branch. */
3867 tree_try_redirect_by_replacing_jump (edge e
, basic_block target
)
3869 basic_block src
= e
->src
;
3870 block_stmt_iterator b
;
3873 /* We can replace or remove a complex jump only when we have exactly
3875 if (EDGE_COUNT (src
->succs
) != 2
3876 /* Verify that all targets will be TARGET. Specifically, the
3877 edge that is not E must also go to TARGET. */
3878 || EDGE_SUCC (src
, EDGE_SUCC (src
, 0) == e
)->dest
!= target
)
3884 stmt
= bsi_stmt (b
);
3886 if (TREE_CODE (stmt
) == COND_EXPR
3887 || TREE_CODE (stmt
) == SWITCH_EXPR
)
3890 e
= ssa_redirect_edge (e
, target
);
3891 e
->flags
= EDGE_FALLTHRU
;
3899 /* Redirect E to DEST. Return NULL on failure. Otherwise, return the
3900 edge representing the redirected branch. */
3903 tree_redirect_edge_and_branch (edge e
, basic_block dest
)
3905 basic_block bb
= e
->src
;
3906 block_stmt_iterator bsi
;
3910 if (e
->flags
& (EDGE_ABNORMAL_CALL
| EDGE_EH
))
3913 if (e
->src
!= ENTRY_BLOCK_PTR
3914 && (ret
= tree_try_redirect_by_replacing_jump (e
, dest
)))
3917 if (e
->dest
== dest
)
3920 label
= tree_block_label (dest
);
3922 bsi
= bsi_last (bb
);
3923 stmt
= bsi_end_p (bsi
) ? NULL
: bsi_stmt (bsi
);
3925 switch (stmt
? TREE_CODE (stmt
) : ERROR_MARK
)
3928 stmt
= (e
->flags
& EDGE_TRUE_VALUE
3929 ? COND_EXPR_THEN (stmt
)
3930 : COND_EXPR_ELSE (stmt
));
3931 GOTO_DESTINATION (stmt
) = label
;
3935 /* No non-abnormal edges should lead from a non-simple goto, and
3936 simple ones should be represented implicitly. */
3941 tree cases
= get_cases_for_edge (e
, stmt
);
3943 /* If we have a list of cases associated with E, then use it
3944 as it's a lot faster than walking the entire case vector. */
3947 edge e2
= find_edge (e
->src
, dest
);
3954 CASE_LABEL (cases
) = label
;
3955 cases
= TREE_CHAIN (cases
);
3958 /* If there was already an edge in the CFG, then we need
3959 to move all the cases associated with E to E2. */
3962 tree cases2
= get_cases_for_edge (e2
, stmt
);
3964 TREE_CHAIN (last
) = TREE_CHAIN (cases2
);
3965 TREE_CHAIN (cases2
) = first
;
3970 tree vec
= SWITCH_LABELS (stmt
);
3971 size_t i
, n
= TREE_VEC_LENGTH (vec
);
3973 for (i
= 0; i
< n
; i
++)
3975 tree elt
= TREE_VEC_ELT (vec
, i
);
3977 if (label_to_block (CASE_LABEL (elt
)) == e
->dest
)
3978 CASE_LABEL (elt
) = label
;
3987 e
->flags
|= EDGE_FALLTHRU
;
3991 /* Otherwise it must be a fallthru edge, and we don't need to
3992 do anything besides redirecting it. */
3993 gcc_assert (e
->flags
& EDGE_FALLTHRU
);
3997 /* Update/insert PHI nodes as necessary. */
3999 /* Now update the edges in the CFG. */
4000 e
= ssa_redirect_edge (e
, dest
);
4006 /* Simple wrapper, as we can always redirect fallthru edges. */
4009 tree_redirect_edge_and_branch_force (edge e
, basic_block dest
)
4011 e
= tree_redirect_edge_and_branch (e
, dest
);
4018 /* Splits basic block BB after statement STMT (but at least after the
4019 labels). If STMT is NULL, BB is split just after the labels. */
4022 tree_split_block (basic_block bb
, void *stmt
)
4024 block_stmt_iterator bsi
, bsi_tgt
;
4030 new_bb
= create_empty_bb (bb
);
4032 /* Redirect the outgoing edges. */
4033 new_bb
->succs
= bb
->succs
;
4035 FOR_EACH_EDGE (e
, ei
, new_bb
->succs
)
4038 if (stmt
&& TREE_CODE ((tree
) stmt
) == LABEL_EXPR
)
4041 /* Move everything from BSI to the new basic block. */
4042 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
4044 act
= bsi_stmt (bsi
);
4045 if (TREE_CODE (act
) == LABEL_EXPR
)
4058 bsi_tgt
= bsi_start (new_bb
);
4059 while (!bsi_end_p (bsi
))
4061 act
= bsi_stmt (bsi
);
4063 bsi_insert_after (&bsi_tgt
, act
, BSI_NEW_STMT
);
4070 /* Moves basic block BB after block AFTER. */
4073 tree_move_block_after (basic_block bb
, basic_block after
)
4075 if (bb
->prev_bb
== after
)
4079 link_block (bb
, after
);
4085 /* Return true if basic_block can be duplicated. */
4088 tree_can_duplicate_bb_p (basic_block bb ATTRIBUTE_UNUSED
)
4094 /* Create a duplicate of the basic block BB. NOTE: This does not
4095 preserve SSA form. */
4098 tree_duplicate_bb (basic_block bb
)
4101 block_stmt_iterator bsi
, bsi_tgt
;
4104 new_bb
= create_empty_bb (EXIT_BLOCK_PTR
->prev_bb
);
4106 /* Copy the PHI nodes. We ignore PHI node arguments here because
4107 the incoming edges have not been setup yet. */
4108 for (phi
= phi_nodes (bb
); phi
; phi
= PHI_CHAIN (phi
))
4110 tree copy
= create_phi_node (PHI_RESULT (phi
), new_bb
);
4111 create_new_def_for (PHI_RESULT (copy
), copy
, PHI_RESULT_PTR (copy
));
4114 /* Keep the chain of PHI nodes in the same order so that they can be
4115 updated by ssa_redirect_edge. */
4116 set_phi_nodes (new_bb
, phi_reverse (phi_nodes (new_bb
)));
4118 bsi_tgt
= bsi_start (new_bb
);
4119 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
4121 def_operand_p def_p
;
4122 ssa_op_iter op_iter
;
4126 stmt
= bsi_stmt (bsi
);
4127 if (TREE_CODE (stmt
) == LABEL_EXPR
)
4130 /* Create a new copy of STMT and duplicate STMT's virtual
4132 copy
= unshare_expr (stmt
);
4133 bsi_insert_after (&bsi_tgt
, copy
, BSI_NEW_STMT
);
4134 copy_virtual_operands (copy
, stmt
);
4135 region
= lookup_stmt_eh_region (stmt
);
4137 add_stmt_to_eh_region (copy
, region
);
4139 /* Create new names for all the definitions created by COPY and
4140 add replacement mappings for each new name. */
4141 FOR_EACH_SSA_DEF_OPERAND (def_p
, copy
, op_iter
, SSA_OP_ALL_DEFS
)
4142 create_new_def_for (DEF_FROM_PTR (def_p
), copy
, def_p
);
4149 /* Basic block BB_COPY was created by code duplication. Add phi node
4150 arguments for edges going out of BB_COPY. The blocks that were
4151 duplicated have rbi->duplicated set to one. */
4154 add_phi_args_after_copy_bb (basic_block bb_copy
)
4156 basic_block bb
, dest
;
4159 tree phi
, phi_copy
, phi_next
, def
;
4161 bb
= bb_copy
->rbi
->original
;
4163 FOR_EACH_EDGE (e_copy
, ei
, bb_copy
->succs
)
4165 if (!phi_nodes (e_copy
->dest
))
4168 if (e_copy
->dest
->rbi
->duplicated
)
4169 dest
= e_copy
->dest
->rbi
->original
;
4171 dest
= e_copy
->dest
;
4173 e
= find_edge (bb
, dest
);
4176 /* During loop unrolling the target of the latch edge is copied.
4177 In this case we are not looking for edge to dest, but to
4178 duplicated block whose original was dest. */
4179 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
4180 if (e
->dest
->rbi
->duplicated
4181 && e
->dest
->rbi
->original
== dest
)
4184 gcc_assert (e
!= NULL
);
4187 for (phi
= phi_nodes (e
->dest
), phi_copy
= phi_nodes (e_copy
->dest
);
4189 phi
= phi_next
, phi_copy
= PHI_CHAIN (phi_copy
))
4191 phi_next
= PHI_CHAIN (phi
);
4192 def
= PHI_ARG_DEF_FROM_EDGE (phi
, e
);
4193 add_phi_arg (phi_copy
, def
, e_copy
);
4198 /* Blocks in REGION_COPY array of length N_REGION were created by
4199 duplication of basic blocks. Add phi node arguments for edges
4200 going from these blocks. */
4203 add_phi_args_after_copy (basic_block
*region_copy
, unsigned n_region
)
4207 for (i
= 0; i
< n_region
; i
++)
4208 region_copy
[i
]->rbi
->duplicated
= 1;
4210 for (i
= 0; i
< n_region
; i
++)
4211 add_phi_args_after_copy_bb (region_copy
[i
]);
4213 for (i
= 0; i
< n_region
; i
++)
4214 region_copy
[i
]->rbi
->duplicated
= 0;
4217 /* Duplicates a REGION (set of N_REGION basic blocks) with just a single
4218 important exit edge EXIT. By important we mean that no SSA name defined
4219 inside region is live over the other exit edges of the region. All entry
4220 edges to the region must go to ENTRY->dest. The edge ENTRY is redirected
4221 to the duplicate of the region. SSA form, dominance and loop information
4222 is updated. The new basic blocks are stored to REGION_COPY in the same
4223 order as they had in REGION, provided that REGION_COPY is not NULL.
4224 The function returns false if it is unable to copy the region,
4228 tree_duplicate_sese_region (edge entry
, edge exit
,
4229 basic_block
*region
, unsigned n_region
,
4230 basic_block
*region_copy
)
4233 bool free_region_copy
= false, copying_header
= false;
4234 struct loop
*loop
= entry
->dest
->loop_father
;
4238 int total_freq
, entry_freq
;
4240 if (!can_copy_bbs_p (region
, n_region
))
4243 /* Some sanity checking. Note that we do not check for all possible
4244 missuses of the functions. I.e. if you ask to copy something weird,
4245 it will work, but the state of structures probably will not be
4247 for (i
= 0; i
< n_region
; i
++)
4249 /* We do not handle subloops, i.e. all the blocks must belong to the
4251 if (region
[i
]->loop_father
!= loop
)
4254 if (region
[i
] != entry
->dest
4255 && region
[i
] == loop
->header
)
4261 /* In case the function is used for loop header copying (which is the primary
4262 use), ensure that EXIT and its copy will be new latch and entry edges. */
4263 if (loop
->header
== entry
->dest
)
4265 copying_header
= true;
4266 loop
->copy
= loop
->outer
;
4268 if (!dominated_by_p (CDI_DOMINATORS
, loop
->latch
, exit
->src
))
4271 for (i
= 0; i
< n_region
; i
++)
4272 if (region
[i
] != exit
->src
4273 && dominated_by_p (CDI_DOMINATORS
, region
[i
], exit
->src
))
4279 region_copy
= xmalloc (sizeof (basic_block
) * n_region
);
4280 free_region_copy
= true;
4283 gcc_assert (!need_ssa_update_p ());
4285 /* Record blocks outside the region that are dominated by something
4287 doms
= xmalloc (sizeof (basic_block
) * n_basic_blocks
);
4288 n_doms
= get_dominated_by_region (CDI_DOMINATORS
, region
, n_region
, doms
);
4290 total_freq
= entry
->dest
->frequency
;
4291 entry_freq
= EDGE_FREQUENCY (entry
);
4292 /* Fix up corner cases, to avoid division by zero or creation of negative
4294 if (total_freq
== 0)
4296 else if (entry_freq
> total_freq
)
4297 entry_freq
= total_freq
;
4299 copy_bbs (region
, n_region
, region_copy
, &exit
, 1, &exit_copy
, loop
);
4300 scale_bbs_frequencies_int (region
, n_region
, total_freq
- entry_freq
,
4302 scale_bbs_frequencies_int (region_copy
, n_region
, entry_freq
, total_freq
);
4306 loop
->header
= exit
->dest
;
4307 loop
->latch
= exit
->src
;
4310 /* Redirect the entry and add the phi node arguments. */
4311 redirected
= redirect_edge_and_branch (entry
, entry
->dest
->rbi
->copy
);
4312 gcc_assert (redirected
!= NULL
);
4313 flush_pending_stmts (entry
);
4315 /* Concerning updating of dominators: We must recount dominators
4316 for entry block and its copy. Anything that is outside of the
4317 region, but was dominated by something inside needs recounting as
4319 set_immediate_dominator (CDI_DOMINATORS
, entry
->dest
, entry
->src
);
4320 doms
[n_doms
++] = entry
->dest
->rbi
->original
;
4321 iterate_fix_dominators (CDI_DOMINATORS
, doms
, n_doms
);
4324 /* Add the other PHI node arguments. */
4325 add_phi_args_after_copy (region_copy
, n_region
);
4327 /* Update the SSA web. */
4328 update_ssa (TODO_update_ssa
);
4330 if (free_region_copy
)
4337 /* Dump FUNCTION_DECL FN to file FILE using FLAGS (see TDF_* in tree.h) */
4340 dump_function_to_file (tree fn
, FILE *file
, int flags
)
4342 tree arg
, vars
, var
;
4343 bool ignore_topmost_bind
= false, any_var
= false;
4347 fprintf (file
, "%s (", lang_hooks
.decl_printable_name (fn
, 2));
4349 arg
= DECL_ARGUMENTS (fn
);
4352 print_generic_expr (file
, arg
, dump_flags
);
4353 if (TREE_CHAIN (arg
))
4354 fprintf (file
, ", ");
4355 arg
= TREE_CHAIN (arg
);
4357 fprintf (file
, ")\n");
4359 if (flags
& TDF_DETAILS
)
4360 dump_eh_tree (file
, DECL_STRUCT_FUNCTION (fn
));
4361 if (flags
& TDF_RAW
)
4363 dump_node (fn
, TDF_SLIM
| flags
, file
);
4367 /* When GIMPLE is lowered, the variables are no longer available in
4368 BIND_EXPRs, so display them separately. */
4369 if (cfun
&& cfun
->decl
== fn
&& cfun
->unexpanded_var_list
)
4371 ignore_topmost_bind
= true;
4373 fprintf (file
, "{\n");
4374 for (vars
= cfun
->unexpanded_var_list
; vars
; vars
= TREE_CHAIN (vars
))
4376 var
= TREE_VALUE (vars
);
4378 print_generic_decl (file
, var
, flags
);
4379 fprintf (file
, "\n");
4385 if (cfun
&& cfun
->decl
== fn
&& cfun
->cfg
&& basic_block_info
)
4387 /* Make a CFG based dump. */
4388 check_bb_profile (ENTRY_BLOCK_PTR
, file
);
4389 if (!ignore_topmost_bind
)
4390 fprintf (file
, "{\n");
4392 if (any_var
&& n_basic_blocks
)
4393 fprintf (file
, "\n");
4396 dump_generic_bb (file
, bb
, 2, flags
);
4398 fprintf (file
, "}\n");
4399 check_bb_profile (EXIT_BLOCK_PTR
, file
);
4405 /* Make a tree based dump. */
4406 chain
= DECL_SAVED_TREE (fn
);
4408 if (TREE_CODE (chain
) == BIND_EXPR
)
4410 if (ignore_topmost_bind
)
4412 chain
= BIND_EXPR_BODY (chain
);
4420 if (!ignore_topmost_bind
)
4421 fprintf (file
, "{\n");
4426 fprintf (file
, "\n");
4428 print_generic_stmt_indented (file
, chain
, flags
, indent
);
4429 if (ignore_topmost_bind
)
4430 fprintf (file
, "}\n");
4433 fprintf (file
, "\n\n");
4437 /* Pretty print of the loops intermediate representation. */
4438 static void print_loop (FILE *, struct loop
*, int);
4439 static void print_pred_bbs (FILE *, basic_block bb
);
4440 static void print_succ_bbs (FILE *, basic_block bb
);
4443 /* Print the predecessors indexes of edge E on FILE. */
4446 print_pred_bbs (FILE *file
, basic_block bb
)
4451 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
4452 fprintf (file
, "bb_%d", e
->src
->index
);
4456 /* Print the successors indexes of edge E on FILE. */
4459 print_succ_bbs (FILE *file
, basic_block bb
)
4464 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
4465 fprintf (file
, "bb_%d", e
->src
->index
);
4469 /* Pretty print LOOP on FILE, indented INDENT spaces. */
4472 print_loop (FILE *file
, struct loop
*loop
, int indent
)
4480 s_indent
= (char *) alloca ((size_t) indent
+ 1);
4481 memset ((void *) s_indent
, ' ', (size_t) indent
);
4482 s_indent
[indent
] = '\0';
4484 /* Print the loop's header. */
4485 fprintf (file
, "%sloop_%d\n", s_indent
, loop
->num
);
4487 /* Print the loop's body. */
4488 fprintf (file
, "%s{\n", s_indent
);
4490 if (bb
->loop_father
== loop
)
4492 /* Print the basic_block's header. */
4493 fprintf (file
, "%s bb_%d (preds = {", s_indent
, bb
->index
);
4494 print_pred_bbs (file
, bb
);
4495 fprintf (file
, "}, succs = {");
4496 print_succ_bbs (file
, bb
);
4497 fprintf (file
, "})\n");
4499 /* Print the basic_block's body. */
4500 fprintf (file
, "%s {\n", s_indent
);
4501 tree_dump_bb (bb
, file
, indent
+ 4);
4502 fprintf (file
, "%s }\n", s_indent
);
4505 print_loop (file
, loop
->inner
, indent
+ 2);
4506 fprintf (file
, "%s}\n", s_indent
);
4507 print_loop (file
, loop
->next
, indent
);
4511 /* Follow a CFG edge from the entry point of the program, and on entry
4512 of a loop, pretty print the loop structure on FILE. */
4515 print_loop_ir (FILE *file
)
4519 bb
= BASIC_BLOCK (0);
4520 if (bb
&& bb
->loop_father
)
4521 print_loop (file
, bb
->loop_father
, 0);
4525 /* Debugging loops structure at tree level. */
4528 debug_loop_ir (void)
4530 print_loop_ir (stderr
);
4534 /* Return true if BB ends with a call, possibly followed by some
4535 instructions that must stay with the call. Return false,
4539 tree_block_ends_with_call_p (basic_block bb
)
4541 block_stmt_iterator bsi
= bsi_last (bb
);
4542 return get_call_expr_in (bsi_stmt (bsi
)) != NULL
;
4546 /* Return true if BB ends with a conditional branch. Return false,
4550 tree_block_ends_with_condjump_p (basic_block bb
)
4552 tree stmt
= last_stmt (bb
);
4553 return (stmt
&& TREE_CODE (stmt
) == COND_EXPR
);
4557 /* Return true if we need to add fake edge to exit at statement T.
4558 Helper function for tree_flow_call_edges_add. */
4561 need_fake_edge_p (tree t
)
4565 /* NORETURN and LONGJMP calls already have an edge to exit.
4566 CONST and PURE calls do not need one.
4567 We don't currently check for CONST and PURE here, although
4568 it would be a good idea, because those attributes are
4569 figured out from the RTL in mark_constant_function, and
4570 the counter incrementation code from -fprofile-arcs
4571 leads to different results from -fbranch-probabilities. */
4572 call
= get_call_expr_in (t
);
4574 && !(call_expr_flags (call
) & ECF_NORETURN
))
4577 if (TREE_CODE (t
) == ASM_EXPR
4578 && (ASM_VOLATILE_P (t
) || ASM_INPUT_P (t
)))
4585 /* Add fake edges to the function exit for any non constant and non
4586 noreturn calls, volatile inline assembly in the bitmap of blocks
4587 specified by BLOCKS or to the whole CFG if BLOCKS is zero. Return
4588 the number of blocks that were split.
4590 The goal is to expose cases in which entering a basic block does
4591 not imply that all subsequent instructions must be executed. */
4594 tree_flow_call_edges_add (sbitmap blocks
)
4597 int blocks_split
= 0;
4598 int last_bb
= last_basic_block
;
4599 bool check_last_block
= false;
4601 if (n_basic_blocks
== 0)
4605 check_last_block
= true;
4607 check_last_block
= TEST_BIT (blocks
, EXIT_BLOCK_PTR
->prev_bb
->index
);
4609 /* In the last basic block, before epilogue generation, there will be
4610 a fallthru edge to EXIT. Special care is required if the last insn
4611 of the last basic block is a call because make_edge folds duplicate
4612 edges, which would result in the fallthru edge also being marked
4613 fake, which would result in the fallthru edge being removed by
4614 remove_fake_edges, which would result in an invalid CFG.
4616 Moreover, we can't elide the outgoing fake edge, since the block
4617 profiler needs to take this into account in order to solve the minimal
4618 spanning tree in the case that the call doesn't return.
4620 Handle this by adding a dummy instruction in a new last basic block. */
4621 if (check_last_block
)
4623 basic_block bb
= EXIT_BLOCK_PTR
->prev_bb
;
4624 block_stmt_iterator bsi
= bsi_last (bb
);
4626 if (!bsi_end_p (bsi
))
4629 if (need_fake_edge_p (t
))
4633 e
= find_edge (bb
, EXIT_BLOCK_PTR
);
4636 bsi_insert_on_edge (e
, build_empty_stmt ());
4637 bsi_commit_edge_inserts ();
4642 /* Now add fake edges to the function exit for any non constant
4643 calls since there is no way that we can determine if they will
4645 for (i
= 0; i
< last_bb
; i
++)
4647 basic_block bb
= BASIC_BLOCK (i
);
4648 block_stmt_iterator bsi
;
4649 tree stmt
, last_stmt
;
4654 if (blocks
&& !TEST_BIT (blocks
, i
))
4657 bsi
= bsi_last (bb
);
4658 if (!bsi_end_p (bsi
))
4660 last_stmt
= bsi_stmt (bsi
);
4663 stmt
= bsi_stmt (bsi
);
4664 if (need_fake_edge_p (stmt
))
4667 /* The handling above of the final block before the
4668 epilogue should be enough to verify that there is
4669 no edge to the exit block in CFG already.
4670 Calling make_edge in such case would cause us to
4671 mark that edge as fake and remove it later. */
4672 #ifdef ENABLE_CHECKING
4673 if (stmt
== last_stmt
)
4675 e
= find_edge (bb
, EXIT_BLOCK_PTR
);
4676 gcc_assert (e
== NULL
);
4680 /* Note that the following may create a new basic block
4681 and renumber the existing basic blocks. */
4682 if (stmt
!= last_stmt
)
4684 e
= split_block (bb
, stmt
);
4688 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
4692 while (!bsi_end_p (bsi
));
4697 verify_flow_info ();
4699 return blocks_split
;
4703 tree_purge_dead_eh_edges (basic_block bb
)
4705 bool changed
= false;
4708 tree stmt
= last_stmt (bb
);
4710 if (stmt
&& tree_can_throw_internal (stmt
))
4713 for (ei
= ei_start (bb
->succs
); (e
= ei_safe_edge (ei
)); )
4715 if (e
->flags
& EDGE_EH
)
4724 /* Removal of dead EH edges might change dominators of not
4725 just immediate successors. E.g. when bb1 is changed so that
4726 it no longer can throw and bb1->bb3 and bb1->bb4 are dead
4727 eh edges purged by this function in:
4739 idom(bb5) must be recomputed. For now just free the dominance
4742 free_dominance_info (CDI_DOMINATORS
);
4748 tree_purge_all_dead_eh_edges (bitmap blocks
)
4750 bool changed
= false;
4754 EXECUTE_IF_SET_IN_BITMAP (blocks
, 0, i
, bi
)
4756 changed
|= tree_purge_dead_eh_edges (BASIC_BLOCK (i
));
4762 /* This function is called whenever a new edge is created or
4766 tree_execute_on_growing_pred (edge e
)
4768 basic_block bb
= e
->dest
;
4771 reserve_phi_args_for_new_edge (bb
);
4774 /* This function is called immediately before edge E is removed from
4775 the edge vector E->dest->preds. */
4778 tree_execute_on_shrinking_pred (edge e
)
4780 if (phi_nodes (e
->dest
))
4781 remove_phi_args (e
);
4784 /*---------------------------------------------------------------------------
4785 Helper functions for Loop versioning
4786 ---------------------------------------------------------------------------*/
4788 /* Adjust phi nodes for 'first' basic block. 'second' basic block is a copy
4789 of 'first'. Both of them are dominated by 'new_head' basic block. When
4790 'new_head' was created by 'second's incoming edge it received phi arguments
4791 on the edge by split_edge(). Later, additional edge 'e' was created to
4792 connect 'new_head' and 'first'. Now this routine adds phi args on this
4793 additional edge 'e' that new_head to second edge received as part of edge
4798 tree_lv_adjust_loop_header_phi (basic_block first
, basic_block second
,
4799 basic_block new_head
, edge e
)
4802 edge e2
= find_edge (new_head
, second
);
4804 /* Because NEW_HEAD has been created by splitting SECOND's incoming
4805 edge, we should always have an edge from NEW_HEAD to SECOND. */
4806 gcc_assert (e2
!= NULL
);
4808 /* Browse all 'second' basic block phi nodes and add phi args to
4809 edge 'e' for 'first' head. PHI args are always in correct order. */
4811 for (phi2
= phi_nodes (second
), phi1
= phi_nodes (first
);
4813 phi2
= PHI_CHAIN (phi2
), phi1
= PHI_CHAIN (phi1
))
4815 tree def
= PHI_ARG_DEF (phi2
, e2
->dest_idx
);
4816 add_phi_arg (phi1
, def
, e
);
4820 /* Adds a if else statement to COND_BB with condition COND_EXPR.
4821 SECOND_HEAD is the destination of the THEN and FIRST_HEAD is
4822 the destination of the ELSE part. */
4824 tree_lv_add_condition_to_bb (basic_block first_head
, basic_block second_head
,
4825 basic_block cond_bb
, void *cond_e
)
4827 block_stmt_iterator bsi
;
4828 tree goto1
= NULL_TREE
;
4829 tree goto2
= NULL_TREE
;
4830 tree new_cond_expr
= NULL_TREE
;
4831 tree cond_expr
= (tree
) cond_e
;
4834 /* Build new conditional expr */
4835 goto1
= build1 (GOTO_EXPR
, void_type_node
, tree_block_label (first_head
));
4836 goto2
= build1 (GOTO_EXPR
, void_type_node
, tree_block_label (second_head
));
4837 new_cond_expr
= build3 (COND_EXPR
, void_type_node
, cond_expr
, goto1
, goto2
);
4839 /* Add new cond in cond_bb. */
4840 bsi
= bsi_start (cond_bb
);
4841 bsi_insert_after (&bsi
, new_cond_expr
, BSI_NEW_STMT
);
4842 /* Adjust edges appropriately to connect new head with first head
4843 as well as second head. */
4844 e0
= single_succ_edge (cond_bb
);
4845 e0
->flags
&= ~EDGE_FALLTHRU
;
4846 e0
->flags
|= EDGE_FALSE_VALUE
;
4849 struct cfg_hooks tree_cfg_hooks
= {
4851 tree_verify_flow_info
,
4852 tree_dump_bb
, /* dump_bb */
4853 create_bb
, /* create_basic_block */
4854 tree_redirect_edge_and_branch
,/* redirect_edge_and_branch */
4855 tree_redirect_edge_and_branch_force
,/* redirect_edge_and_branch_force */
4856 remove_bb
, /* delete_basic_block */
4857 tree_split_block
, /* split_block */
4858 tree_move_block_after
, /* move_block_after */
4859 tree_can_merge_blocks_p
, /* can_merge_blocks_p */
4860 tree_merge_blocks
, /* merge_blocks */
4861 tree_predict_edge
, /* predict_edge */
4862 tree_predicted_by_p
, /* predicted_by_p */
4863 tree_can_duplicate_bb_p
, /* can_duplicate_block_p */
4864 tree_duplicate_bb
, /* duplicate_block */
4865 tree_split_edge
, /* split_edge */
4866 tree_make_forwarder_block
, /* make_forward_block */
4867 NULL
, /* tidy_fallthru_edge */
4868 tree_block_ends_with_call_p
, /* block_ends_with_call_p */
4869 tree_block_ends_with_condjump_p
, /* block_ends_with_condjump_p */
4870 tree_flow_call_edges_add
, /* flow_call_edges_add */
4871 tree_execute_on_growing_pred
, /* execute_on_growing_pred */
4872 tree_execute_on_shrinking_pred
, /* execute_on_shrinking_pred */
4873 tree_duplicate_loop_to_header_edge
, /* duplicate loop for trees */
4874 tree_lv_add_condition_to_bb
, /* lv_add_condition_to_bb */
4875 tree_lv_adjust_loop_header_phi
, /* lv_adjust_loop_header_phi*/
4876 extract_true_false_edges_from_block
, /* extract_cond_bb_edges */
4877 flush_pending_stmts
/* flush_pending_stmts */
4881 /* Split all critical edges. */
4884 split_critical_edges (void)
4890 /* split_edge can redirect edges out of SWITCH_EXPRs, which can get
4891 expensive. So we want to enable recording of edge to CASE_LABEL_EXPR
4892 mappings around the calls to split_edge. */
4893 start_recording_case_labels ();
4896 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
4897 if (EDGE_CRITICAL_P (e
) && !(e
->flags
& EDGE_ABNORMAL
))
4902 end_recording_case_labels ();
4905 struct tree_opt_pass pass_split_crit_edges
=
4907 "crited", /* name */
4909 split_critical_edges
, /* execute */
4912 0, /* static_pass_number */
4913 TV_TREE_SPLIT_EDGES
, /* tv_id */
4914 PROP_cfg
, /* properties required */
4915 PROP_no_crit_edges
, /* properties_provided */
4916 0, /* properties_destroyed */
4917 0, /* todo_flags_start */
4918 TODO_dump_func
, /* todo_flags_finish */
4923 /* Return EXP if it is a valid GIMPLE rvalue, else gimplify it into
4924 a temporary, make sure and register it to be renamed if necessary,
4925 and finally return the temporary. Put the statements to compute
4926 EXP before the current statement in BSI. */
4929 gimplify_val (block_stmt_iterator
*bsi
, tree type
, tree exp
)
4931 tree t
, new_stmt
, orig_stmt
;
4933 if (is_gimple_val (exp
))
4936 t
= make_rename_temp (type
, NULL
);
4937 new_stmt
= build (MODIFY_EXPR
, type
, t
, exp
);
4939 orig_stmt
= bsi_stmt (*bsi
);
4940 SET_EXPR_LOCUS (new_stmt
, EXPR_LOCUS (orig_stmt
));
4941 TREE_BLOCK (new_stmt
) = TREE_BLOCK (orig_stmt
);
4943 bsi_insert_before (bsi
, new_stmt
, BSI_SAME_STMT
);
4948 /* Build a ternary operation and gimplify it. Emit code before BSI.
4949 Return the gimple_val holding the result. */
4952 gimplify_build3 (block_stmt_iterator
*bsi
, enum tree_code code
,
4953 tree type
, tree a
, tree b
, tree c
)
4957 ret
= fold (build3 (code
, type
, a
, b
, c
));
4960 return gimplify_val (bsi
, type
, ret
);
4963 /* Build a binary operation and gimplify it. Emit code before BSI.
4964 Return the gimple_val holding the result. */
4967 gimplify_build2 (block_stmt_iterator
*bsi
, enum tree_code code
,
4968 tree type
, tree a
, tree b
)
4972 ret
= fold (build2 (code
, type
, a
, b
));
4975 return gimplify_val (bsi
, type
, ret
);
4978 /* Build a unary operation and gimplify it. Emit code before BSI.
4979 Return the gimple_val holding the result. */
4982 gimplify_build1 (block_stmt_iterator
*bsi
, enum tree_code code
, tree type
,
4987 ret
= fold (build1 (code
, type
, a
));
4990 return gimplify_val (bsi
, type
, ret
);
4995 /* Emit return warnings. */
4998 execute_warn_function_return (void)
5000 #ifdef USE_MAPPED_LOCATION
5001 source_location location
;
5009 /* If we have a path to EXIT, then we do return. */
5010 if (TREE_THIS_VOLATILE (cfun
->decl
)
5011 && EDGE_COUNT (EXIT_BLOCK_PTR
->preds
) > 0)
5013 #ifdef USE_MAPPED_LOCATION
5014 location
= UNKNOWN_LOCATION
;
5018 FOR_EACH_EDGE (e
, ei
, EXIT_BLOCK_PTR
->preds
)
5020 last
= last_stmt (e
->src
);
5021 if (TREE_CODE (last
) == RETURN_EXPR
5022 #ifdef USE_MAPPED_LOCATION
5023 && (location
= EXPR_LOCATION (last
)) != UNKNOWN_LOCATION
)
5025 && (locus
= EXPR_LOCUS (last
)) != NULL
)
5029 #ifdef USE_MAPPED_LOCATION
5030 if (location
== UNKNOWN_LOCATION
)
5031 location
= cfun
->function_end_locus
;
5032 warning (0, "%H%<noreturn%> function does return", &location
);
5035 locus
= &cfun
->function_end_locus
;
5036 warning (0, "%H%<noreturn%> function does return", locus
);
5040 /* If we see "return;" in some basic block, then we do reach the end
5041 without returning a value. */
5042 else if (warn_return_type
5043 && !TREE_NO_WARNING (cfun
->decl
)
5044 && EDGE_COUNT (EXIT_BLOCK_PTR
->preds
) > 0
5045 && !VOID_TYPE_P (TREE_TYPE (TREE_TYPE (cfun
->decl
))))
5047 FOR_EACH_EDGE (e
, ei
, EXIT_BLOCK_PTR
->preds
)
5049 tree last
= last_stmt (e
->src
);
5050 if (TREE_CODE (last
) == RETURN_EXPR
5051 && TREE_OPERAND (last
, 0) == NULL
)
5053 #ifdef USE_MAPPED_LOCATION
5054 location
= EXPR_LOCATION (last
);
5055 if (location
== UNKNOWN_LOCATION
)
5056 location
= cfun
->function_end_locus
;
5057 warning (0, "%Hcontrol reaches end of non-void function", &location
);
5059 locus
= EXPR_LOCUS (last
);
5061 locus
= &cfun
->function_end_locus
;
5062 warning (0, "%Hcontrol reaches end of non-void function", locus
);
5064 TREE_NO_WARNING (cfun
->decl
) = 1;
5072 /* Given a basic block B which ends with a conditional and has
5073 precisely two successors, determine which of the edges is taken if
5074 the conditional is true and which is taken if the conditional is
5075 false. Set TRUE_EDGE and FALSE_EDGE appropriately. */
5078 extract_true_false_edges_from_block (basic_block b
,
5082 edge e
= EDGE_SUCC (b
, 0);
5084 if (e
->flags
& EDGE_TRUE_VALUE
)
5087 *false_edge
= EDGE_SUCC (b
, 1);
5092 *true_edge
= EDGE_SUCC (b
, 1);
5096 struct tree_opt_pass pass_warn_function_return
=
5100 execute_warn_function_return
, /* execute */
5103 0, /* static_pass_number */
5105 PROP_cfg
, /* properties_required */
5106 0, /* properties_provided */
5107 0, /* properties_destroyed */
5108 0, /* todo_flags_start */
5109 0, /* todo_flags_finish */
5113 /* Emit noreturn warnings. */
5116 execute_warn_function_noreturn (void)
5118 if (warn_missing_noreturn
5119 && !TREE_THIS_VOLATILE (cfun
->decl
)
5120 && EDGE_COUNT (EXIT_BLOCK_PTR
->preds
) == 0
5121 && !lang_hooks
.function
.missing_noreturn_ok_p (cfun
->decl
))
5122 warning (0, "%Jfunction might be possible candidate for "
5123 "attribute %<noreturn%>",
5127 struct tree_opt_pass pass_warn_function_noreturn
=
5131 execute_warn_function_noreturn
, /* execute */
5134 0, /* static_pass_number */
5136 PROP_cfg
, /* properties_required */
5137 0, /* properties_provided */
5138 0, /* properties_destroyed */
5139 0, /* todo_flags_start */
5140 0, /* todo_flags_finish */