1 /* Control flow functions for trees.
2 Copyright (C) 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
3 Contributed by Diego Novillo <dnovillo@redhat.com>
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 GCC is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to
19 the Free Software Foundation, 59 Temple Place - Suite 330,
20 Boston, MA 02111-1307, USA. */
24 #include "coretypes.h"
29 #include "hard-reg-set.h"
30 #include "basic-block.h"
37 #include "langhooks.h"
38 #include "diagnostic.h"
39 #include "tree-flow.h"
41 #include "tree-dump.h"
42 #include "tree-pass.h"
46 #include "cfglayout.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 /* Mapping of labels to their associated blocks. This can greatly speed up
58 building of the CFG in code with lots of gotos. */
59 static GTY(()) varray_type label_to_block_map
;
61 /* This hash table allows us to efficiently lookup all CASE_LABEL_EXPRs
62 which use a particular edge. The CASE_LABEL_EXPRs are chained together
63 via their TREE_CHAIN field, which we clear after we're done with the
64 hash table to prevent problems with duplication of SWITCH_EXPRs.
66 Access to this list of CASE_LABEL_EXPRs allows us to efficiently
67 update the case vector in response to edge redirections.
69 Right now this table is set up and torn down at key points in the
70 compilation process. It would be nice if we could make the table
71 more persistent. The key is getting notification of changes to
72 the CFG (particularly edge removal, creation and redirection). */
74 struct edge_to_cases_elt
76 /* The edge itself. Necessary for hashing and equality tests. */
79 /* The case labels associated with this edge. We link these up via
80 their TREE_CHAIN field, then we wipe out the TREE_CHAIN fields
81 when we destroy the hash table. This prevents problems when copying
86 static htab_t edge_to_cases
;
91 long num_merged_labels
;
94 static struct cfg_stats_d cfg_stats
;
96 /* Nonzero if we found a computed goto while building basic blocks. */
97 static bool found_computed_goto
;
99 /* Basic blocks and flowgraphs. */
100 static basic_block
create_bb (void *, void *, basic_block
);
101 static void create_block_annotation (basic_block
);
102 static void free_blocks_annotations (void);
103 static void clear_blocks_annotations (void);
104 static void make_blocks (tree
);
105 static void factor_computed_gotos (void);
108 static void make_edges (void);
109 static void make_ctrl_stmt_edges (basic_block
);
110 static void make_exit_edges (basic_block
);
111 static void make_cond_expr_edges (basic_block
);
112 static void make_switch_expr_edges (basic_block
);
113 static void make_goto_expr_edges (basic_block
);
114 static edge
tree_redirect_edge_and_branch (edge
, basic_block
);
115 static edge
tree_try_redirect_by_replacing_jump (edge
, basic_block
);
116 static void split_critical_edges (void);
118 /* Various helpers. */
119 static inline bool stmt_starts_bb_p (tree
, tree
);
120 static int tree_verify_flow_info (void);
121 static void tree_make_forwarder_block (edge
);
122 static bool thread_jumps (void);
123 static bool tree_forwarder_block_p (basic_block
);
124 static void tree_cfg2vcg (FILE *);
126 /* Flowgraph optimization and cleanup. */
127 static void tree_merge_blocks (basic_block
, basic_block
);
128 static bool tree_can_merge_blocks_p (basic_block
, basic_block
);
129 static void remove_bb (basic_block
);
130 static bool cleanup_control_flow (void);
131 static bool cleanup_control_expr_graph (basic_block
, block_stmt_iterator
);
132 static edge
find_taken_edge_cond_expr (basic_block
, tree
);
133 static edge
find_taken_edge_switch_expr (basic_block
, tree
);
134 static tree
find_case_label_for_value (tree
, tree
);
135 static bool phi_alternatives_equal (basic_block
, edge
, edge
);
138 /*---------------------------------------------------------------------------
140 ---------------------------------------------------------------------------*/
142 /* Entry point to the CFG builder for trees. TP points to the list of
143 statements to be added to the flowgraph. */
146 build_tree_cfg (tree
*tp
)
148 /* Register specific tree functions. */
149 tree_register_cfg_hooks ();
151 /* Initialize rbi_pool. */
154 /* Initialize the basic block array. */
156 profile_status
= PROFILE_ABSENT
;
158 last_basic_block
= 0;
159 VARRAY_BB_INIT (basic_block_info
, initial_cfg_capacity
, "basic_block_info");
160 memset ((void *) &cfg_stats
, 0, sizeof (cfg_stats
));
162 /* Build a mapping of labels to their associated blocks. */
163 VARRAY_BB_INIT (label_to_block_map
, initial_cfg_capacity
,
164 "label to block map");
166 ENTRY_BLOCK_PTR
->next_bb
= EXIT_BLOCK_PTR
;
167 EXIT_BLOCK_PTR
->prev_bb
= ENTRY_BLOCK_PTR
;
169 found_computed_goto
= 0;
172 /* Computed gotos are hell to deal with, especially if there are
173 lots of them with a large number of destinations. So we factor
174 them to a common computed goto location before we build the
175 edge list. After we convert back to normal form, we will un-factor
176 the computed gotos since factoring introduces an unwanted jump. */
177 if (found_computed_goto
)
178 factor_computed_gotos ();
180 /* Make sure there is always at least one block, even if it's empty. */
181 if (n_basic_blocks
== 0)
182 create_empty_bb (ENTRY_BLOCK_PTR
);
184 create_block_annotation (ENTRY_BLOCK_PTR
);
185 create_block_annotation (EXIT_BLOCK_PTR
);
187 /* Adjust the size of the array. */
188 VARRAY_GROW (basic_block_info
, n_basic_blocks
);
190 /* To speed up statement iterator walks, we first purge dead labels. */
191 cleanup_dead_labels ();
193 /* Group case nodes to reduce the number of edges.
194 We do this after cleaning up dead labels because otherwise we miss
195 a lot of obvious case merging opportunities. */
196 group_case_labels ();
198 /* Create the edges of the flowgraph. */
201 /* Debugging dumps. */
203 /* Write the flowgraph to a VCG file. */
205 int local_dump_flags
;
206 FILE *dump_file
= dump_begin (TDI_vcg
, &local_dump_flags
);
209 tree_cfg2vcg (dump_file
);
210 dump_end (TDI_vcg
, dump_file
);
214 /* Dump a textual representation of the flowgraph. */
216 dump_tree_cfg (dump_file
, dump_flags
);
220 execute_build_cfg (void)
222 build_tree_cfg (&DECL_SAVED_TREE (current_function_decl
));
225 struct tree_opt_pass pass_build_cfg
=
229 execute_build_cfg
, /* execute */
232 0, /* static_pass_number */
233 TV_TREE_CFG
, /* tv_id */
234 PROP_gimple_leh
, /* properties_required */
235 PROP_cfg
, /* properties_provided */
236 0, /* properties_destroyed */
237 0, /* todo_flags_start */
238 TODO_verify_stmts
, /* todo_flags_finish */
242 /* Search the CFG for any computed gotos. If found, factor them to a
243 common computed goto site. Also record the location of that site so
244 that we can un-factor the gotos after we have converted back to
248 factor_computed_gotos (void)
251 tree factored_label_decl
= NULL
;
253 tree factored_computed_goto_label
= NULL
;
254 tree factored_computed_goto
= NULL
;
256 /* We know there are one or more computed gotos in this function.
257 Examine the last statement in each basic block to see if the block
258 ends with a computed goto. */
262 block_stmt_iterator bsi
= bsi_last (bb
);
267 last
= bsi_stmt (bsi
);
269 /* Ignore the computed goto we create when we factor the original
271 if (last
== factored_computed_goto
)
274 /* If the last statement is a computed goto, factor it. */
275 if (computed_goto_p (last
))
279 /* The first time we find a computed goto we need to create
280 the factored goto block and the variable each original
281 computed goto will use for their goto destination. */
282 if (! factored_computed_goto
)
284 basic_block new_bb
= create_empty_bb (bb
);
285 block_stmt_iterator new_bsi
= bsi_start (new_bb
);
287 /* Create the destination of the factored goto. Each original
288 computed goto will put its desired destination into this
289 variable and jump to the label we create immediately
291 var
= create_tmp_var (ptr_type_node
, "gotovar");
293 /* Build a label for the new block which will contain the
294 factored computed goto. */
295 factored_label_decl
= create_artificial_label ();
296 factored_computed_goto_label
297 = build1 (LABEL_EXPR
, void_type_node
, factored_label_decl
);
298 bsi_insert_after (&new_bsi
, factored_computed_goto_label
,
301 /* Build our new computed goto. */
302 factored_computed_goto
= build1 (GOTO_EXPR
, void_type_node
, var
);
303 bsi_insert_after (&new_bsi
, factored_computed_goto
,
307 /* Copy the original computed goto's destination into VAR. */
308 assignment
= build (MODIFY_EXPR
, ptr_type_node
,
309 var
, GOTO_DESTINATION (last
));
310 bsi_insert_before (&bsi
, assignment
, BSI_SAME_STMT
);
312 /* And re-vector the computed goto to the new destination. */
313 GOTO_DESTINATION (last
) = factored_label_decl
;
319 /* Create annotations for a single basic block. */
322 create_block_annotation (basic_block bb
)
324 /* Verify that the tree_annotations field is clear. */
325 gcc_assert (!bb
->tree_annotations
);
326 bb
->tree_annotations
= ggc_alloc_cleared (sizeof (struct bb_ann_d
));
330 /* Free the annotations for all the basic blocks. */
332 static void free_blocks_annotations (void)
334 clear_blocks_annotations ();
338 /* Clear the annotations for all the basic blocks. */
341 clear_blocks_annotations (void)
345 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
, NULL
, next_bb
)
346 bb
->tree_annotations
= NULL
;
350 /* Build a flowgraph for the statement_list STMT_LIST. */
353 make_blocks (tree stmt_list
)
355 tree_stmt_iterator i
= tsi_start (stmt_list
);
357 bool start_new_block
= true;
358 bool first_stmt_of_list
= true;
359 basic_block bb
= ENTRY_BLOCK_PTR
;
361 while (!tsi_end_p (i
))
368 /* If the statement starts a new basic block or if we have determined
369 in a previous pass that we need to create a new block for STMT, do
371 if (start_new_block
|| stmt_starts_bb_p (stmt
, prev_stmt
))
373 if (!first_stmt_of_list
)
374 stmt_list
= tsi_split_statement_list_before (&i
);
375 bb
= create_basic_block (stmt_list
, NULL
, bb
);
376 start_new_block
= false;
379 /* Now add STMT to BB and create the subgraphs for special statement
381 set_bb_for_stmt (stmt
, bb
);
383 if (computed_goto_p (stmt
))
384 found_computed_goto
= true;
386 /* If STMT is a basic block terminator, set START_NEW_BLOCK for the
388 if (stmt_ends_bb_p (stmt
))
389 start_new_block
= true;
392 first_stmt_of_list
= false;
397 /* Create and return a new empty basic block after bb AFTER. */
400 create_bb (void *h
, void *e
, basic_block after
)
406 /* Create and initialize a new basic block. Since alloc_block uses
407 ggc_alloc_cleared to allocate a basic block, we do not have to
408 clear the newly allocated basic block here. */
411 bb
->index
= last_basic_block
;
413 bb
->stmt_list
= h
? h
: alloc_stmt_list ();
415 /* Add the new block to the linked list of blocks. */
416 link_block (bb
, after
);
418 /* Grow the basic block array if needed. */
419 if ((size_t) last_basic_block
== VARRAY_SIZE (basic_block_info
))
421 size_t new_size
= last_basic_block
+ (last_basic_block
+ 3) / 4;
422 VARRAY_GROW (basic_block_info
, new_size
);
425 /* Add the newly created block to the array. */
426 BASIC_BLOCK (last_basic_block
) = bb
;
428 create_block_annotation (bb
);
433 initialize_bb_rbi (bb
);
438 /*---------------------------------------------------------------------------
440 ---------------------------------------------------------------------------*/
442 /* Join all the blocks in the flowgraph. */
449 /* Create an edge from entry to the first block with executable
451 make_edge (ENTRY_BLOCK_PTR
, BASIC_BLOCK (0), EDGE_FALLTHRU
);
453 /* Traverse basic block array placing edges. */
456 tree first
= first_stmt (bb
);
457 tree last
= last_stmt (bb
);
461 /* Edges for statements that always alter flow control. */
462 if (is_ctrl_stmt (last
))
463 make_ctrl_stmt_edges (bb
);
465 /* Edges for statements that sometimes alter flow control. */
466 if (is_ctrl_altering_stmt (last
))
467 make_exit_edges (bb
);
470 /* Finally, if no edges were created above, this is a regular
471 basic block that only needs a fallthru edge. */
472 if (EDGE_COUNT (bb
->succs
) == 0)
473 make_edge (bb
, bb
->next_bb
, EDGE_FALLTHRU
);
476 /* We do not care about fake edges, so remove any that the CFG
477 builder inserted for completeness. */
478 remove_fake_exit_edges ();
480 /* Clean up the graph and warn for unreachable code. */
485 /* Create edges for control statement at basic block BB. */
488 make_ctrl_stmt_edges (basic_block bb
)
490 tree last
= last_stmt (bb
);
493 switch (TREE_CODE (last
))
496 make_goto_expr_edges (bb
);
500 make_edge (bb
, EXIT_BLOCK_PTR
, 0);
504 make_cond_expr_edges (bb
);
508 make_switch_expr_edges (bb
);
512 make_eh_edges (last
);
513 /* Yet another NORETURN hack. */
514 if (EDGE_COUNT (bb
->succs
) == 0)
515 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
524 /* Create exit edges for statements in block BB that alter the flow of
525 control. Statements that alter the control flow are 'goto', 'return'
526 and calls to non-returning functions. */
529 make_exit_edges (basic_block bb
)
531 tree last
= last_stmt (bb
), op
;
534 switch (TREE_CODE (last
))
537 /* If this function receives a nonlocal goto, then we need to
538 make edges from this call site to all the nonlocal goto
540 if (TREE_SIDE_EFFECTS (last
)
541 && current_function_has_nonlocal_label
)
542 make_goto_expr_edges (bb
);
544 /* If this statement has reachable exception handlers, then
545 create abnormal edges to them. */
546 make_eh_edges (last
);
548 /* Some calls are known not to return. For such calls we create
551 We really need to revamp how we build edges so that it's not
552 such a bloody pain to avoid creating edges for this case since
553 all we do is remove these edges when we're done building the
555 if (call_expr_flags (last
) & ECF_NORETURN
)
557 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
561 /* Don't forget the fall-thru edge. */
562 make_edge (bb
, bb
->next_bb
, EDGE_FALLTHRU
);
566 /* A MODIFY_EXPR may have a CALL_EXPR on its RHS and the CALL_EXPR
567 may have an abnormal edge. Search the RHS for this case and
568 create any required edges. */
569 op
= get_call_expr_in (last
);
570 if (op
&& TREE_SIDE_EFFECTS (op
)
571 && current_function_has_nonlocal_label
)
572 make_goto_expr_edges (bb
);
574 make_eh_edges (last
);
575 make_edge (bb
, bb
->next_bb
, EDGE_FALLTHRU
);
584 /* Create the edges for a COND_EXPR starting at block BB.
585 At this point, both clauses must contain only simple gotos. */
588 make_cond_expr_edges (basic_block bb
)
590 tree entry
= last_stmt (bb
);
591 basic_block then_bb
, else_bb
;
592 tree then_label
, else_label
;
595 gcc_assert (TREE_CODE (entry
) == COND_EXPR
);
597 /* Entry basic blocks for each component. */
598 then_label
= GOTO_DESTINATION (COND_EXPR_THEN (entry
));
599 else_label
= GOTO_DESTINATION (COND_EXPR_ELSE (entry
));
600 then_bb
= label_to_block (then_label
);
601 else_bb
= label_to_block (else_label
);
603 make_edge (bb
, then_bb
, EDGE_TRUE_VALUE
);
604 make_edge (bb
, else_bb
, EDGE_FALSE_VALUE
);
607 /* Hashing routine for EDGE_TO_CASES. */
610 edge_to_cases_hash (const void *p
)
612 edge e
= ((struct edge_to_cases_elt
*)p
)->e
;
614 /* Hash on the edge itself (which is a pointer). */
615 return htab_hash_pointer (e
);
618 /* Equality routine for EDGE_TO_CASES, edges are unique, so testing
619 for equality is just a pointer comparison. */
622 edge_to_cases_eq (const void *p1
, const void *p2
)
624 edge e1
= ((struct edge_to_cases_elt
*)p1
)->e
;
625 edge e2
= ((struct edge_to_cases_elt
*)p2
)->e
;
630 /* Called for each element in the hash table (P) as we delete the
631 edge to cases hash table.
633 Clear all the TREE_CHAINs to prevent problems with copying of
634 SWITCH_EXPRs and structure sharing rules, then free the hash table
638 edge_to_cases_cleanup (void *p
)
640 struct edge_to_cases_elt
*elt
= p
;
643 for (t
= elt
->case_labels
; t
; t
= next
)
645 next
= TREE_CHAIN (t
);
646 TREE_CHAIN (t
) = NULL
;
651 /* Start recording information mapping edges to case labels. */
654 start_recording_case_labels (void)
656 gcc_assert (edge_to_cases
== NULL
);
658 edge_to_cases
= htab_create (37,
661 edge_to_cases_cleanup
);
664 /* Return nonzero if we are recording information for case labels. */
667 recording_case_labels_p (void)
669 return (edge_to_cases
!= NULL
);
672 /* Stop recording information mapping edges to case labels and
673 remove any information we have recorded. */
675 end_recording_case_labels (void)
677 htab_delete (edge_to_cases
);
678 edge_to_cases
= NULL
;
681 /* Record that CASE_LABEL (a CASE_LABEL_EXPR) references edge E. */
684 record_switch_edge (edge e
, tree case_label
)
686 struct edge_to_cases_elt
*elt
;
689 /* Build a hash table element so we can see if E is already
691 elt
= xmalloc (sizeof (struct edge_to_cases_elt
));
693 elt
->case_labels
= case_label
;
695 slot
= htab_find_slot (edge_to_cases
, elt
, INSERT
);
699 /* E was not in the hash table. Install E into the hash table. */
704 /* E was already in the hash table. Free ELT as we do not need it
708 /* Get the entry stored in the hash table. */
709 elt
= (struct edge_to_cases_elt
*) *slot
;
711 /* Add it to the chain of CASE_LABEL_EXPRs referencing E. */
712 TREE_CHAIN (case_label
) = elt
->case_labels
;
713 elt
->case_labels
= case_label
;
717 /* If we are inside a {start,end}_recording_cases block, then return
718 a chain of CASE_LABEL_EXPRs from T which reference E.
720 Otherwise return NULL. */
723 get_cases_for_edge (edge e
, tree t
)
725 struct edge_to_cases_elt elt
, *elt_p
;
730 /* If we are not recording cases, then we do not have CASE_LABEL_EXPR
731 chains available. Return NULL so the caller can detect this case. */
732 if (!recording_case_labels_p ())
737 elt
.case_labels
= NULL
;
738 slot
= htab_find_slot (edge_to_cases
, &elt
, NO_INSERT
);
742 elt_p
= (struct edge_to_cases_elt
*)*slot
;
743 return elt_p
->case_labels
;
746 /* If we did not find E in the hash table, then this must be the first
747 time we have been queried for information about E & T. Add all the
748 elements from T to the hash table then perform the query again. */
750 vec
= SWITCH_LABELS (t
);
751 n
= TREE_VEC_LENGTH (vec
);
752 for (i
= 0; i
< n
; i
++)
754 tree lab
= CASE_LABEL (TREE_VEC_ELT (vec
, i
));
755 basic_block label_bb
= label_to_block (lab
);
756 record_switch_edge (find_edge (e
->src
, label_bb
), TREE_VEC_ELT (vec
, i
));
761 /* Create the edges for a SWITCH_EXPR starting at block BB.
762 At this point, the switch body has been lowered and the
763 SWITCH_LABELS filled in, so this is in effect a multi-way branch. */
766 make_switch_expr_edges (basic_block bb
)
768 tree entry
= last_stmt (bb
);
772 vec
= SWITCH_LABELS (entry
);
773 n
= TREE_VEC_LENGTH (vec
);
775 for (i
= 0; i
< n
; ++i
)
777 tree lab
= CASE_LABEL (TREE_VEC_ELT (vec
, i
));
778 basic_block label_bb
= label_to_block (lab
);
779 make_edge (bb
, label_bb
, 0);
784 /* Return the basic block holding label DEST. */
787 label_to_block (tree dest
)
789 int uid
= LABEL_DECL_UID (dest
);
791 /* We would die hard when faced by an undefined label. Emit a label to
792 the very first basic block. This will hopefully make even the dataflow
793 and undefined variable warnings quite right. */
794 if ((errorcount
|| sorrycount
) && uid
< 0)
796 block_stmt_iterator bsi
= bsi_start (BASIC_BLOCK (0));
799 stmt
= build1 (LABEL_EXPR
, void_type_node
, dest
);
800 bsi_insert_before (&bsi
, stmt
, BSI_NEW_STMT
);
801 uid
= LABEL_DECL_UID (dest
);
803 return VARRAY_BB (label_to_block_map
, uid
);
807 /* Create edges for a goto statement at block BB. */
810 make_goto_expr_edges (basic_block bb
)
813 basic_block target_bb
;
815 block_stmt_iterator last
= bsi_last (bb
);
817 goto_t
= bsi_stmt (last
);
819 /* If the last statement is not a GOTO (i.e., it is a RETURN_EXPR,
820 CALL_EXPR or MODIFY_EXPR), then the edge is an abnormal edge resulting
821 from a nonlocal goto. */
822 if (TREE_CODE (goto_t
) != GOTO_EXPR
)
824 dest
= error_mark_node
;
829 dest
= GOTO_DESTINATION (goto_t
);
832 /* A GOTO to a local label creates normal edges. */
833 if (simple_goto_p (goto_t
))
835 edge e
= make_edge (bb
, label_to_block (dest
), EDGE_FALLTHRU
);
836 #ifdef USE_MAPPED_LOCATION
837 e
->goto_locus
= EXPR_LOCATION (goto_t
);
839 e
->goto_locus
= EXPR_LOCUS (goto_t
);
845 /* Nothing more to do for nonlocal gotos. */
846 if (TREE_CODE (dest
) == LABEL_DECL
)
849 /* Computed gotos remain. */
852 /* Look for the block starting with the destination label. In the
853 case of a computed goto, make an edge to any label block we find
855 FOR_EACH_BB (target_bb
)
857 block_stmt_iterator bsi
;
859 for (bsi
= bsi_start (target_bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
861 tree target
= bsi_stmt (bsi
);
863 if (TREE_CODE (target
) != LABEL_EXPR
)
867 /* Computed GOTOs. Make an edge to every label block that has
868 been marked as a potential target for a computed goto. */
869 (FORCED_LABEL (LABEL_EXPR_LABEL (target
)) && for_call
== 0)
870 /* Nonlocal GOTO target. Make an edge to every label block
871 that has been marked as a potential target for a nonlocal
873 || (DECL_NONLOCAL (LABEL_EXPR_LABEL (target
)) && for_call
== 1))
875 make_edge (bb
, target_bb
, EDGE_ABNORMAL
);
881 /* Degenerate case of computed goto with no labels. */
882 if (!for_call
&& EDGE_COUNT (bb
->succs
) == 0)
883 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
887 /*---------------------------------------------------------------------------
889 ---------------------------------------------------------------------------*/
891 /* Remove unreachable blocks and other miscellaneous clean up work. */
894 cleanup_tree_cfg (void)
898 timevar_push (TV_TREE_CLEANUP_CFG
);
900 retval
= cleanup_control_flow ();
901 retval
|= delete_unreachable_blocks ();
903 /* thread_jumps can redirect edges out of SWITCH_EXPRs, which can get
904 expensive. So we want to enable recording of edge to CASE_LABEL_EXPR
905 mappings around the call to thread_jumps. */
906 start_recording_case_labels ();
907 retval
|= thread_jumps ();
908 end_recording_case_labels ();
910 #ifdef ENABLE_CHECKING
913 gcc_assert (!cleanup_control_flow ());
914 gcc_assert (!delete_unreachable_blocks ());
915 gcc_assert (!thread_jumps ());
919 /* Merging the blocks creates no new opportunities for the other
920 optimizations, so do it here. */
925 #ifdef ENABLE_CHECKING
928 timevar_pop (TV_TREE_CLEANUP_CFG
);
933 /* Cleanup useless labels in basic blocks. This is something we wish
934 to do early because it allows us to group case labels before creating
935 the edges for the CFG, and it speeds up block statement iterators in
937 We only run this pass once, running it more than once is probably not
940 /* A map from basic block index to the leading label of that block. */
941 static tree
*label_for_bb
;
943 /* Callback for for_each_eh_region. Helper for cleanup_dead_labels. */
945 update_eh_label (struct eh_region
*region
)
947 tree old_label
= get_eh_region_tree_label (region
);
951 basic_block bb
= label_to_block (old_label
);
953 /* ??? After optimizing, there may be EH regions with labels
954 that have already been removed from the function body, so
955 there is no basic block for them. */
959 new_label
= label_for_bb
[bb
->index
];
960 set_eh_region_tree_label (region
, new_label
);
964 /* Given LABEL return the first label in the same basic block. */
966 main_block_label (tree label
)
968 basic_block bb
= label_to_block (label
);
970 /* label_to_block possibly inserted undefined label into the chain. */
971 if (!label_for_bb
[bb
->index
])
972 label_for_bb
[bb
->index
] = label
;
973 return label_for_bb
[bb
->index
];
976 /* Cleanup redundant labels. This is a three-step process:
977 1) Find the leading label for each block.
978 2) Redirect all references to labels to the leading labels.
979 3) Cleanup all useless labels. */
982 cleanup_dead_labels (void)
985 label_for_bb
= xcalloc (last_basic_block
, sizeof (tree
));
987 /* Find a suitable label for each block. We use the first user-defined
988 label if there is one, or otherwise just the first label we see. */
991 block_stmt_iterator i
;
993 for (i
= bsi_start (bb
); !bsi_end_p (i
); bsi_next (&i
))
995 tree label
, stmt
= bsi_stmt (i
);
997 if (TREE_CODE (stmt
) != LABEL_EXPR
)
1000 label
= LABEL_EXPR_LABEL (stmt
);
1002 /* If we have not yet seen a label for the current block,
1003 remember this one and see if there are more labels. */
1004 if (! label_for_bb
[bb
->index
])
1006 label_for_bb
[bb
->index
] = label
;
1010 /* If we did see a label for the current block already, but it
1011 is an artificially created label, replace it if the current
1012 label is a user defined label. */
1013 if (! DECL_ARTIFICIAL (label
)
1014 && DECL_ARTIFICIAL (label_for_bb
[bb
->index
]))
1016 label_for_bb
[bb
->index
] = label
;
1022 /* Now redirect all jumps/branches to the selected label.
1023 First do so for each block ending in a control statement. */
1026 tree stmt
= last_stmt (bb
);
1030 switch (TREE_CODE (stmt
))
1034 tree true_branch
, false_branch
;
1036 true_branch
= COND_EXPR_THEN (stmt
);
1037 false_branch
= COND_EXPR_ELSE (stmt
);
1039 GOTO_DESTINATION (true_branch
)
1040 = main_block_label (GOTO_DESTINATION (true_branch
));
1041 GOTO_DESTINATION (false_branch
)
1042 = main_block_label (GOTO_DESTINATION (false_branch
));
1050 tree vec
= SWITCH_LABELS (stmt
);
1051 size_t n
= TREE_VEC_LENGTH (vec
);
1053 /* Replace all destination labels. */
1054 for (i
= 0; i
< n
; ++i
)
1056 tree elt
= TREE_VEC_ELT (vec
, i
);
1057 tree label
= main_block_label (CASE_LABEL (elt
));
1058 CASE_LABEL (elt
) = label
;
1063 /* We have to handle GOTO_EXPRs until they're removed, and we don't
1064 remove them until after we've created the CFG edges. */
1066 if (! computed_goto_p (stmt
))
1068 GOTO_DESTINATION (stmt
)
1069 = main_block_label (GOTO_DESTINATION (stmt
));
1078 for_each_eh_region (update_eh_label
);
1080 /* Finally, purge dead labels. All user-defined labels and labels that
1081 can be the target of non-local gotos are preserved. */
1084 block_stmt_iterator i
;
1085 tree label_for_this_bb
= label_for_bb
[bb
->index
];
1087 if (! label_for_this_bb
)
1090 for (i
= bsi_start (bb
); !bsi_end_p (i
); )
1092 tree label
, stmt
= bsi_stmt (i
);
1094 if (TREE_CODE (stmt
) != LABEL_EXPR
)
1097 label
= LABEL_EXPR_LABEL (stmt
);
1099 if (label
== label_for_this_bb
1100 || ! DECL_ARTIFICIAL (label
)
1101 || DECL_NONLOCAL (label
))
1108 free (label_for_bb
);
1111 /* Look for blocks ending in a multiway branch (a SWITCH_EXPR in GIMPLE),
1112 and scan the sorted vector of cases. Combine the ones jumping to the
1114 Eg. three separate entries 1: 2: 3: become one entry 1..3: */
1117 group_case_labels (void)
1123 tree stmt
= last_stmt (bb
);
1124 if (stmt
&& TREE_CODE (stmt
) == SWITCH_EXPR
)
1126 tree labels
= SWITCH_LABELS (stmt
);
1127 int old_size
= TREE_VEC_LENGTH (labels
);
1128 int i
, j
, new_size
= old_size
;
1129 tree default_case
= TREE_VEC_ELT (labels
, old_size
- 1);
1132 /* The default label is always the last case in a switch
1133 statement after gimplification. */
1134 default_label
= CASE_LABEL (default_case
);
1136 /* Look for possible opportunities to merge cases.
1137 Ignore the last element of the label vector because it
1138 must be the default case. */
1140 while (i
< old_size
- 1)
1142 tree base_case
, base_label
, base_high
, type
;
1143 base_case
= TREE_VEC_ELT (labels
, i
);
1145 gcc_assert (base_case
);
1146 base_label
= CASE_LABEL (base_case
);
1148 /* Discard cases that have the same destination as the
1150 if (base_label
== default_label
)
1152 TREE_VEC_ELT (labels
, i
) = NULL_TREE
;
1158 type
= TREE_TYPE (CASE_LOW (base_case
));
1159 base_high
= CASE_HIGH (base_case
) ?
1160 CASE_HIGH (base_case
) : CASE_LOW (base_case
);
1162 /* Try to merge case labels. Break out when we reach the end
1163 of the label vector or when we cannot merge the next case
1164 label with the current one. */
1165 while (i
< old_size
- 1)
1167 tree merge_case
= TREE_VEC_ELT (labels
, i
);
1168 tree merge_label
= CASE_LABEL (merge_case
);
1169 tree t
= int_const_binop (PLUS_EXPR
, base_high
,
1170 integer_one_node
, 1);
1172 /* Merge the cases if they jump to the same place,
1173 and their ranges are consecutive. */
1174 if (merge_label
== base_label
1175 && tree_int_cst_equal (CASE_LOW (merge_case
), t
))
1177 base_high
= CASE_HIGH (merge_case
) ?
1178 CASE_HIGH (merge_case
) : CASE_LOW (merge_case
);
1179 CASE_HIGH (base_case
) = base_high
;
1180 TREE_VEC_ELT (labels
, i
) = NULL_TREE
;
1189 /* Compress the case labels in the label vector, and adjust the
1190 length of the vector. */
1191 for (i
= 0, j
= 0; i
< new_size
; i
++)
1193 while (! TREE_VEC_ELT (labels
, j
))
1195 TREE_VEC_ELT (labels
, i
) = TREE_VEC_ELT (labels
, j
++);
1197 TREE_VEC_LENGTH (labels
) = new_size
;
1202 /* Checks whether we can merge block B into block A. */
1205 tree_can_merge_blocks_p (basic_block a
, basic_block b
)
1208 block_stmt_iterator bsi
;
1210 if (EDGE_COUNT (a
->succs
) != 1)
1213 if (EDGE_SUCC (a
, 0)->flags
& EDGE_ABNORMAL
)
1216 if (EDGE_SUCC (a
, 0)->dest
!= b
)
1219 if (b
== EXIT_BLOCK_PTR
)
1222 if (EDGE_COUNT (b
->preds
) > 1)
1225 /* If A ends by a statement causing exceptions or something similar, we
1226 cannot merge the blocks. */
1227 stmt
= last_stmt (a
);
1228 if (stmt
&& stmt_ends_bb_p (stmt
))
1231 /* Do not allow a block with only a non-local label to be merged. */
1232 if (stmt
&& TREE_CODE (stmt
) == LABEL_EXPR
1233 && DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt
)))
1236 /* There may be no phi nodes at the start of b. Most of these degenerate
1237 phi nodes should be cleaned up by kill_redundant_phi_nodes. */
1241 /* Do not remove user labels. */
1242 for (bsi
= bsi_start (b
); !bsi_end_p (bsi
); bsi_next (&bsi
))
1244 stmt
= bsi_stmt (bsi
);
1245 if (TREE_CODE (stmt
) != LABEL_EXPR
)
1247 if (!DECL_ARTIFICIAL (LABEL_EXPR_LABEL (stmt
)))
1255 /* Merge block B into block A. */
1258 tree_merge_blocks (basic_block a
, basic_block b
)
1260 block_stmt_iterator bsi
;
1261 tree_stmt_iterator last
;
1264 fprintf (dump_file
, "Merging blocks %d and %d\n", a
->index
, b
->index
);
1266 /* Ensure that B follows A. */
1267 move_block_after (b
, a
);
1269 gcc_assert (EDGE_SUCC (a
, 0)->flags
& EDGE_FALLTHRU
);
1270 gcc_assert (!last_stmt (a
) || !stmt_ends_bb_p (last_stmt (a
)));
1272 /* Remove labels from B and set bb_for_stmt to A for other statements. */
1273 for (bsi
= bsi_start (b
); !bsi_end_p (bsi
);)
1275 if (TREE_CODE (bsi_stmt (bsi
)) == LABEL_EXPR
)
1279 set_bb_for_stmt (bsi_stmt (bsi
), a
);
1284 /* Merge the chains. */
1285 last
= tsi_last (a
->stmt_list
);
1286 tsi_link_after (&last
, b
->stmt_list
, TSI_NEW_STMT
);
1287 b
->stmt_list
= NULL
;
1291 /* Walk the function tree removing unnecessary statements.
1293 * Empty statement nodes are removed
1295 * Unnecessary TRY_FINALLY and TRY_CATCH blocks are removed
1297 * Unnecessary COND_EXPRs are removed
1299 * Some unnecessary BIND_EXPRs are removed
1301 Clearly more work could be done. The trick is doing the analysis
1302 and removal fast enough to be a net improvement in compile times.
1304 Note that when we remove a control structure such as a COND_EXPR
1305 BIND_EXPR, or TRY block, we will need to repeat this optimization pass
1306 to ensure we eliminate all the useless code. */
1317 static void remove_useless_stmts_1 (tree
*, struct rus_data
*);
1320 remove_useless_stmts_warn_notreached (tree stmt
)
1322 if (EXPR_HAS_LOCATION (stmt
))
1324 location_t loc
= EXPR_LOCATION (stmt
);
1325 warning ("%Hwill never be executed", &loc
);
1329 switch (TREE_CODE (stmt
))
1331 case STATEMENT_LIST
:
1333 tree_stmt_iterator i
;
1334 for (i
= tsi_start (stmt
); !tsi_end_p (i
); tsi_next (&i
))
1335 if (remove_useless_stmts_warn_notreached (tsi_stmt (i
)))
1341 if (remove_useless_stmts_warn_notreached (COND_EXPR_COND (stmt
)))
1343 if (remove_useless_stmts_warn_notreached (COND_EXPR_THEN (stmt
)))
1345 if (remove_useless_stmts_warn_notreached (COND_EXPR_ELSE (stmt
)))
1349 case TRY_FINALLY_EXPR
:
1350 case TRY_CATCH_EXPR
:
1351 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt
, 0)))
1353 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt
, 1)))
1358 return remove_useless_stmts_warn_notreached (CATCH_BODY (stmt
));
1359 case EH_FILTER_EXPR
:
1360 return remove_useless_stmts_warn_notreached (EH_FILTER_FAILURE (stmt
));
1362 return remove_useless_stmts_warn_notreached (BIND_EXPR_BLOCK (stmt
));
1365 /* Not a live container. */
1373 remove_useless_stmts_cond (tree
*stmt_p
, struct rus_data
*data
)
1375 tree then_clause
, else_clause
, cond
;
1376 bool save_has_label
, then_has_label
, else_has_label
;
1378 save_has_label
= data
->has_label
;
1379 data
->has_label
= false;
1380 data
->last_goto
= NULL
;
1382 remove_useless_stmts_1 (&COND_EXPR_THEN (*stmt_p
), data
);
1384 then_has_label
= data
->has_label
;
1385 data
->has_label
= false;
1386 data
->last_goto
= NULL
;
1388 remove_useless_stmts_1 (&COND_EXPR_ELSE (*stmt_p
), data
);
1390 else_has_label
= data
->has_label
;
1391 data
->has_label
= save_has_label
| then_has_label
| else_has_label
;
1393 then_clause
= COND_EXPR_THEN (*stmt_p
);
1394 else_clause
= COND_EXPR_ELSE (*stmt_p
);
1395 cond
= COND_EXPR_COND (*stmt_p
);
1397 /* If neither arm does anything at all, we can remove the whole IF. */
1398 if (!TREE_SIDE_EFFECTS (then_clause
) && !TREE_SIDE_EFFECTS (else_clause
))
1400 *stmt_p
= build_empty_stmt ();
1401 data
->repeat
= true;
1404 /* If there are no reachable statements in an arm, then we can
1405 zap the entire conditional. */
1406 else if (integer_nonzerop (cond
) && !else_has_label
)
1408 if (warn_notreached
)
1409 remove_useless_stmts_warn_notreached (else_clause
);
1410 *stmt_p
= then_clause
;
1411 data
->repeat
= true;
1413 else if (integer_zerop (cond
) && !then_has_label
)
1415 if (warn_notreached
)
1416 remove_useless_stmts_warn_notreached (then_clause
);
1417 *stmt_p
= else_clause
;
1418 data
->repeat
= true;
1421 /* Check a couple of simple things on then/else with single stmts. */
1424 tree then_stmt
= expr_only (then_clause
);
1425 tree else_stmt
= expr_only (else_clause
);
1427 /* Notice branches to a common destination. */
1428 if (then_stmt
&& else_stmt
1429 && TREE_CODE (then_stmt
) == GOTO_EXPR
1430 && TREE_CODE (else_stmt
) == GOTO_EXPR
1431 && (GOTO_DESTINATION (then_stmt
) == GOTO_DESTINATION (else_stmt
)))
1433 *stmt_p
= then_stmt
;
1434 data
->repeat
= true;
1437 /* If the THEN/ELSE clause merely assigns a value to a variable or
1438 parameter which is already known to contain that value, then
1439 remove the useless THEN/ELSE clause. */
1440 else if (TREE_CODE (cond
) == VAR_DECL
|| TREE_CODE (cond
) == PARM_DECL
)
1443 && TREE_CODE (else_stmt
) == MODIFY_EXPR
1444 && TREE_OPERAND (else_stmt
, 0) == cond
1445 && integer_zerop (TREE_OPERAND (else_stmt
, 1)))
1446 COND_EXPR_ELSE (*stmt_p
) = alloc_stmt_list ();
1448 else if ((TREE_CODE (cond
) == EQ_EXPR
|| TREE_CODE (cond
) == NE_EXPR
)
1449 && (TREE_CODE (TREE_OPERAND (cond
, 0)) == VAR_DECL
1450 || TREE_CODE (TREE_OPERAND (cond
, 0)) == PARM_DECL
)
1451 && TREE_CONSTANT (TREE_OPERAND (cond
, 1)))
1453 tree stmt
= (TREE_CODE (cond
) == EQ_EXPR
1454 ? then_stmt
: else_stmt
);
1455 tree
*location
= (TREE_CODE (cond
) == EQ_EXPR
1456 ? &COND_EXPR_THEN (*stmt_p
)
1457 : &COND_EXPR_ELSE (*stmt_p
));
1460 && TREE_CODE (stmt
) == MODIFY_EXPR
1461 && TREE_OPERAND (stmt
, 0) == TREE_OPERAND (cond
, 0)
1462 && TREE_OPERAND (stmt
, 1) == TREE_OPERAND (cond
, 1))
1463 *location
= alloc_stmt_list ();
1467 /* Protect GOTOs in the arm of COND_EXPRs from being removed. They
1468 would be re-introduced during lowering. */
1469 data
->last_goto
= NULL
;
1474 remove_useless_stmts_tf (tree
*stmt_p
, struct rus_data
*data
)
1476 bool save_may_branch
, save_may_throw
;
1477 bool this_may_branch
, this_may_throw
;
1479 /* Collect may_branch and may_throw information for the body only. */
1480 save_may_branch
= data
->may_branch
;
1481 save_may_throw
= data
->may_throw
;
1482 data
->may_branch
= false;
1483 data
->may_throw
= false;
1484 data
->last_goto
= NULL
;
1486 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p
, 0), data
);
1488 this_may_branch
= data
->may_branch
;
1489 this_may_throw
= data
->may_throw
;
1490 data
->may_branch
|= save_may_branch
;
1491 data
->may_throw
|= save_may_throw
;
1492 data
->last_goto
= NULL
;
1494 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p
, 1), data
);
1496 /* If the body is empty, then we can emit the FINALLY block without
1497 the enclosing TRY_FINALLY_EXPR. */
1498 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p
, 0)))
1500 *stmt_p
= TREE_OPERAND (*stmt_p
, 1);
1501 data
->repeat
= true;
1504 /* If the handler is empty, then we can emit the TRY block without
1505 the enclosing TRY_FINALLY_EXPR. */
1506 else if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p
, 1)))
1508 *stmt_p
= TREE_OPERAND (*stmt_p
, 0);
1509 data
->repeat
= true;
1512 /* If the body neither throws, nor branches, then we can safely
1513 string the TRY and FINALLY blocks together. */
1514 else if (!this_may_branch
&& !this_may_throw
)
1516 tree stmt
= *stmt_p
;
1517 *stmt_p
= TREE_OPERAND (stmt
, 0);
1518 append_to_statement_list (TREE_OPERAND (stmt
, 1), stmt_p
);
1519 data
->repeat
= true;
1525 remove_useless_stmts_tc (tree
*stmt_p
, struct rus_data
*data
)
1527 bool save_may_throw
, this_may_throw
;
1528 tree_stmt_iterator i
;
1531 /* Collect may_throw information for the body only. */
1532 save_may_throw
= data
->may_throw
;
1533 data
->may_throw
= false;
1534 data
->last_goto
= NULL
;
1536 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p
, 0), data
);
1538 this_may_throw
= data
->may_throw
;
1539 data
->may_throw
= save_may_throw
;
1541 /* If the body cannot throw, then we can drop the entire TRY_CATCH_EXPR. */
1542 if (!this_may_throw
)
1544 if (warn_notreached
)
1545 remove_useless_stmts_warn_notreached (TREE_OPERAND (*stmt_p
, 1));
1546 *stmt_p
= TREE_OPERAND (*stmt_p
, 0);
1547 data
->repeat
= true;
1551 /* Process the catch clause specially. We may be able to tell that
1552 no exceptions propagate past this point. */
1554 this_may_throw
= true;
1555 i
= tsi_start (TREE_OPERAND (*stmt_p
, 1));
1556 stmt
= tsi_stmt (i
);
1557 data
->last_goto
= NULL
;
1559 switch (TREE_CODE (stmt
))
1562 for (; !tsi_end_p (i
); tsi_next (&i
))
1564 stmt
= tsi_stmt (i
);
1565 /* If we catch all exceptions, then the body does not
1566 propagate exceptions past this point. */
1567 if (CATCH_TYPES (stmt
) == NULL
)
1568 this_may_throw
= false;
1569 data
->last_goto
= NULL
;
1570 remove_useless_stmts_1 (&CATCH_BODY (stmt
), data
);
1574 case EH_FILTER_EXPR
:
1575 if (EH_FILTER_MUST_NOT_THROW (stmt
))
1576 this_may_throw
= false;
1577 else if (EH_FILTER_TYPES (stmt
) == NULL
)
1578 this_may_throw
= false;
1579 remove_useless_stmts_1 (&EH_FILTER_FAILURE (stmt
), data
);
1583 /* Otherwise this is a cleanup. */
1584 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p
, 1), data
);
1586 /* If the cleanup is empty, then we can emit the TRY block without
1587 the enclosing TRY_CATCH_EXPR. */
1588 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p
, 1)))
1590 *stmt_p
= TREE_OPERAND (*stmt_p
, 0);
1591 data
->repeat
= true;
1595 data
->may_throw
|= this_may_throw
;
1600 remove_useless_stmts_bind (tree
*stmt_p
, struct rus_data
*data
)
1604 /* First remove anything underneath the BIND_EXPR. */
1605 remove_useless_stmts_1 (&BIND_EXPR_BODY (*stmt_p
), data
);
1607 /* If the BIND_EXPR has no variables, then we can pull everything
1608 up one level and remove the BIND_EXPR, unless this is the toplevel
1609 BIND_EXPR for the current function or an inlined function.
1611 When this situation occurs we will want to apply this
1612 optimization again. */
1613 block
= BIND_EXPR_BLOCK (*stmt_p
);
1614 if (BIND_EXPR_VARS (*stmt_p
) == NULL_TREE
1615 && *stmt_p
!= DECL_SAVED_TREE (current_function_decl
)
1617 || ! BLOCK_ABSTRACT_ORIGIN (block
)
1618 || (TREE_CODE (BLOCK_ABSTRACT_ORIGIN (block
))
1621 *stmt_p
= BIND_EXPR_BODY (*stmt_p
);
1622 data
->repeat
= true;
1628 remove_useless_stmts_goto (tree
*stmt_p
, struct rus_data
*data
)
1630 tree dest
= GOTO_DESTINATION (*stmt_p
);
1632 data
->may_branch
= true;
1633 data
->last_goto
= NULL
;
1635 /* Record the last goto expr, so that we can delete it if unnecessary. */
1636 if (TREE_CODE (dest
) == LABEL_DECL
)
1637 data
->last_goto
= stmt_p
;
1642 remove_useless_stmts_label (tree
*stmt_p
, struct rus_data
*data
)
1644 tree label
= LABEL_EXPR_LABEL (*stmt_p
);
1646 data
->has_label
= true;
1648 /* We do want to jump across non-local label receiver code. */
1649 if (DECL_NONLOCAL (label
))
1650 data
->last_goto
= NULL
;
1652 else if (data
->last_goto
&& GOTO_DESTINATION (*data
->last_goto
) == label
)
1654 *data
->last_goto
= build_empty_stmt ();
1655 data
->repeat
= true;
1658 /* ??? Add something here to delete unused labels. */
1662 /* If the function is "const" or "pure", then clear TREE_SIDE_EFFECTS on its
1663 decl. This allows us to eliminate redundant or useless
1664 calls to "const" functions.
1666 Gimplifier already does the same operation, but we may notice functions
1667 being const and pure once their calls has been gimplified, so we need
1668 to update the flag. */
1671 update_call_expr_flags (tree call
)
1673 tree decl
= get_callee_fndecl (call
);
1676 if (call_expr_flags (call
) & (ECF_CONST
| ECF_PURE
))
1677 TREE_SIDE_EFFECTS (call
) = 0;
1678 if (TREE_NOTHROW (decl
))
1679 TREE_NOTHROW (call
) = 1;
1683 /* T is CALL_EXPR. Set current_function_calls_* flags. */
1686 notice_special_calls (tree t
)
1688 int flags
= call_expr_flags (t
);
1690 if (flags
& ECF_MAY_BE_ALLOCA
)
1691 current_function_calls_alloca
= true;
1692 if (flags
& ECF_RETURNS_TWICE
)
1693 current_function_calls_setjmp
= true;
1697 /* Clear flags set by notice_special_calls. Used by dead code removal
1698 to update the flags. */
1701 clear_special_calls (void)
1703 current_function_calls_alloca
= false;
1704 current_function_calls_setjmp
= false;
1709 remove_useless_stmts_1 (tree
*tp
, struct rus_data
*data
)
1713 switch (TREE_CODE (t
))
1716 remove_useless_stmts_cond (tp
, data
);
1719 case TRY_FINALLY_EXPR
:
1720 remove_useless_stmts_tf (tp
, data
);
1723 case TRY_CATCH_EXPR
:
1724 remove_useless_stmts_tc (tp
, data
);
1728 remove_useless_stmts_bind (tp
, data
);
1732 remove_useless_stmts_goto (tp
, data
);
1736 remove_useless_stmts_label (tp
, data
);
1741 data
->last_goto
= NULL
;
1742 data
->may_branch
= true;
1747 data
->last_goto
= NULL
;
1748 notice_special_calls (t
);
1749 update_call_expr_flags (t
);
1750 if (tree_could_throw_p (t
))
1751 data
->may_throw
= true;
1755 data
->last_goto
= NULL
;
1757 op
= get_call_expr_in (t
);
1760 update_call_expr_flags (op
);
1761 notice_special_calls (op
);
1763 if (tree_could_throw_p (t
))
1764 data
->may_throw
= true;
1767 case STATEMENT_LIST
:
1769 tree_stmt_iterator i
= tsi_start (t
);
1770 while (!tsi_end_p (i
))
1773 if (IS_EMPTY_STMT (t
))
1779 remove_useless_stmts_1 (tsi_stmt_ptr (i
), data
);
1782 if (TREE_CODE (t
) == STATEMENT_LIST
)
1784 tsi_link_before (&i
, t
, TSI_SAME_STMT
);
1794 data
->last_goto
= NULL
;
1798 data
->last_goto
= NULL
;
1804 remove_useless_stmts (void)
1806 struct rus_data data
;
1808 clear_special_calls ();
1812 memset (&data
, 0, sizeof (data
));
1813 remove_useless_stmts_1 (&DECL_SAVED_TREE (current_function_decl
), &data
);
1815 while (data
.repeat
);
1819 struct tree_opt_pass pass_remove_useless_stmts
=
1821 "useless", /* name */
1823 remove_useless_stmts
, /* execute */
1826 0, /* static_pass_number */
1828 PROP_gimple_any
, /* properties_required */
1829 0, /* properties_provided */
1830 0, /* properties_destroyed */
1831 0, /* todo_flags_start */
1832 TODO_dump_func
, /* todo_flags_finish */
1837 /* Remove obviously useless statements in basic block BB. */
1840 cfg_remove_useless_stmts_bb (basic_block bb
)
1842 block_stmt_iterator bsi
;
1843 tree stmt
= NULL_TREE
;
1844 tree cond
, var
= NULL_TREE
, val
= NULL_TREE
;
1845 struct var_ann_d
*ann
;
1847 /* Check whether we come here from a condition, and if so, get the
1849 if (EDGE_COUNT (bb
->preds
) != 1
1850 || !(EDGE_PRED (bb
, 0)->flags
& (EDGE_TRUE_VALUE
| EDGE_FALSE_VALUE
)))
1853 cond
= COND_EXPR_COND (last_stmt (EDGE_PRED (bb
, 0)->src
));
1855 if (TREE_CODE (cond
) == VAR_DECL
|| TREE_CODE (cond
) == PARM_DECL
)
1858 val
= (EDGE_PRED (bb
, 0)->flags
& EDGE_FALSE_VALUE
1859 ? boolean_false_node
: boolean_true_node
);
1861 else if (TREE_CODE (cond
) == TRUTH_NOT_EXPR
1862 && (TREE_CODE (TREE_OPERAND (cond
, 0)) == VAR_DECL
1863 || TREE_CODE (TREE_OPERAND (cond
, 0)) == PARM_DECL
))
1865 var
= TREE_OPERAND (cond
, 0);
1866 val
= (EDGE_PRED (bb
, 0)->flags
& EDGE_FALSE_VALUE
1867 ? boolean_true_node
: boolean_false_node
);
1871 if (EDGE_PRED (bb
, 0)->flags
& EDGE_FALSE_VALUE
)
1872 cond
= invert_truthvalue (cond
);
1873 if (TREE_CODE (cond
) == EQ_EXPR
1874 && (TREE_CODE (TREE_OPERAND (cond
, 0)) == VAR_DECL
1875 || TREE_CODE (TREE_OPERAND (cond
, 0)) == PARM_DECL
)
1876 && (TREE_CODE (TREE_OPERAND (cond
, 1)) == VAR_DECL
1877 || TREE_CODE (TREE_OPERAND (cond
, 1)) == PARM_DECL
1878 || TREE_CONSTANT (TREE_OPERAND (cond
, 1))))
1880 var
= TREE_OPERAND (cond
, 0);
1881 val
= TREE_OPERAND (cond
, 1);
1887 /* Only work for normal local variables. */
1888 ann
= var_ann (var
);
1891 || TREE_ADDRESSABLE (var
))
1894 if (! TREE_CONSTANT (val
))
1896 ann
= var_ann (val
);
1899 || TREE_ADDRESSABLE (val
))
1903 /* Ignore floating point variables, since comparison behaves weird for
1905 if (FLOAT_TYPE_P (TREE_TYPE (var
)))
1908 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
);)
1910 stmt
= bsi_stmt (bsi
);
1912 /* If the THEN/ELSE clause merely assigns a value to a variable/parameter
1913 which is already known to contain that value, then remove the useless
1914 THEN/ELSE clause. */
1915 if (TREE_CODE (stmt
) == MODIFY_EXPR
1916 && TREE_OPERAND (stmt
, 0) == var
1917 && operand_equal_p (val
, TREE_OPERAND (stmt
, 1), 0))
1923 /* Invalidate the var if we encounter something that could modify it.
1924 Likewise for the value it was previously set to. Note that we only
1925 consider values that are either a VAR_DECL or PARM_DECL so we
1926 can test for conflict very simply. */
1927 if (TREE_CODE (stmt
) == ASM_EXPR
1928 || (TREE_CODE (stmt
) == MODIFY_EXPR
1929 && (TREE_OPERAND (stmt
, 0) == var
1930 || TREE_OPERAND (stmt
, 0) == val
)))
1938 /* A CFG-aware version of remove_useless_stmts. */
1941 cfg_remove_useless_stmts (void)
1945 #ifdef ENABLE_CHECKING
1946 verify_flow_info ();
1951 cfg_remove_useless_stmts_bb (bb
);
1956 /* Remove PHI nodes associated with basic block BB and all edges out of BB. */
1959 remove_phi_nodes_and_edges_for_unreachable_block (basic_block bb
)
1963 /* Since this block is no longer reachable, we can just delete all
1964 of its PHI nodes. */
1965 phi
= phi_nodes (bb
);
1968 tree next
= PHI_CHAIN (phi
);
1969 remove_phi_node (phi
, NULL_TREE
, bb
);
1973 /* Remove edges to BB's successors. */
1974 while (EDGE_COUNT (bb
->succs
) > 0)
1975 remove_edge (EDGE_SUCC (bb
, 0));
1979 /* Remove statements of basic block BB. */
1982 remove_bb (basic_block bb
)
1984 block_stmt_iterator i
;
1985 source_locus loc
= 0;
1989 fprintf (dump_file
, "Removing basic block %d\n", bb
->index
);
1990 if (dump_flags
& TDF_DETAILS
)
1992 dump_bb (bb
, dump_file
, 0);
1993 fprintf (dump_file
, "\n");
1997 /* Remove all the instructions in the block. */
1998 for (i
= bsi_start (bb
); !bsi_end_p (i
);)
2000 tree stmt
= bsi_stmt (i
);
2001 if (TREE_CODE (stmt
) == LABEL_EXPR
2002 && FORCED_LABEL (LABEL_EXPR_LABEL (stmt
)))
2004 basic_block new_bb
= bb
->prev_bb
;
2005 block_stmt_iterator new_bsi
= bsi_after_labels (new_bb
);
2008 bsi_insert_after (&new_bsi
, stmt
, BSI_NEW_STMT
);
2012 release_defs (stmt
);
2014 set_bb_for_stmt (stmt
, NULL
);
2018 /* Don't warn for removed gotos. Gotos are often removed due to
2019 jump threading, thus resulting in bogus warnings. Not great,
2020 since this way we lose warnings for gotos in the original
2021 program that are indeed unreachable. */
2022 if (TREE_CODE (stmt
) != GOTO_EXPR
&& EXPR_HAS_LOCATION (stmt
) && !loc
)
2023 #ifdef USE_MAPPED_LOCATION
2024 loc
= EXPR_LOCATION (stmt
);
2026 loc
= EXPR_LOCUS (stmt
);
2030 /* If requested, give a warning that the first statement in the
2031 block is unreachable. We walk statements backwards in the
2032 loop above, so the last statement we process is the first statement
2034 if (warn_notreached
&& loc
)
2035 #ifdef USE_MAPPED_LOCATION
2036 warning ("%Hwill never be executed", &loc
);
2038 warning ("%Hwill never be executed", loc
);
2041 remove_phi_nodes_and_edges_for_unreachable_block (bb
);
2044 /* Try to remove superfluous control structures. */
2047 cleanup_control_flow (void)
2050 block_stmt_iterator bsi
;
2051 bool retval
= false;
2056 bsi
= bsi_last (bb
);
2058 if (bsi_end_p (bsi
))
2061 stmt
= bsi_stmt (bsi
);
2062 if (TREE_CODE (stmt
) == COND_EXPR
2063 || TREE_CODE (stmt
) == SWITCH_EXPR
)
2064 retval
|= cleanup_control_expr_graph (bb
, bsi
);
2070 /* Disconnect an unreachable block in the control expression starting
2074 cleanup_control_expr_graph (basic_block bb
, block_stmt_iterator bsi
)
2077 bool retval
= false;
2078 tree expr
= bsi_stmt (bsi
), val
;
2080 if (EDGE_COUNT (bb
->succs
) > 1)
2085 switch (TREE_CODE (expr
))
2088 val
= COND_EXPR_COND (expr
);
2092 val
= SWITCH_COND (expr
);
2093 if (TREE_CODE (val
) != INTEGER_CST
)
2101 taken_edge
= find_taken_edge (bb
, val
);
2105 /* Remove all the edges except the one that is always executed. */
2106 for (ei
= ei_start (bb
->succs
); (e
= ei_safe_edge (ei
)); )
2108 if (e
!= taken_edge
)
2110 taken_edge
->probability
+= e
->probability
;
2111 taken_edge
->count
+= e
->count
;
2118 if (taken_edge
->probability
> REG_BR_PROB_BASE
)
2119 taken_edge
->probability
= REG_BR_PROB_BASE
;
2122 taken_edge
= EDGE_SUCC (bb
, 0);
2125 taken_edge
->flags
= EDGE_FALLTHRU
;
2127 /* We removed some paths from the cfg. */
2128 free_dominance_info (CDI_DOMINATORS
);
2134 /* Given a basic block BB ending with COND_EXPR or SWITCH_EXPR, and a
2135 predicate VAL, return the edge that will be taken out of the block.
2136 If VAL does not match a unique edge, NULL is returned. */
2139 find_taken_edge (basic_block bb
, tree val
)
2143 stmt
= last_stmt (bb
);
2146 gcc_assert (is_ctrl_stmt (stmt
));
2149 /* If VAL is a predicate of the form N RELOP N, where N is an
2150 SSA_NAME, we can usually determine its truth value. */
2151 if (COMPARISON_CLASS_P (val
))
2154 /* If VAL is not a constant, we can't determine which edge might
2156 if (!really_constant_p (val
))
2159 if (TREE_CODE (stmt
) == COND_EXPR
)
2160 return find_taken_edge_cond_expr (bb
, val
);
2162 if (TREE_CODE (stmt
) == SWITCH_EXPR
)
2163 return find_taken_edge_switch_expr (bb
, val
);
2169 /* Given a constant value VAL and the entry block BB to a COND_EXPR
2170 statement, determine which of the two edges will be taken out of the
2171 block. Return NULL if either edge may be taken. */
2174 find_taken_edge_cond_expr (basic_block bb
, tree val
)
2176 edge true_edge
, false_edge
;
2178 extract_true_false_edges_from_block (bb
, &true_edge
, &false_edge
);
2180 /* Otherwise, try to determine which branch of the if() will be taken.
2181 If VAL is a constant but it can't be reduced to a 0 or a 1, then
2182 we don't really know which edge will be taken at runtime. This
2183 may happen when comparing addresses (e.g., if (&var1 == 4)). */
2184 if (integer_nonzerop (val
))
2186 else if (integer_zerop (val
))
2193 /* Given a constant value VAL and the entry block BB to a SWITCH_EXPR
2194 statement, determine which edge will be taken out of the block. Return
2195 NULL if any edge may be taken. */
2198 find_taken_edge_switch_expr (basic_block bb
, tree val
)
2200 tree switch_expr
, taken_case
;
2201 basic_block dest_bb
;
2204 if (TREE_CODE (val
) != INTEGER_CST
)
2207 switch_expr
= last_stmt (bb
);
2208 taken_case
= find_case_label_for_value (switch_expr
, val
);
2209 dest_bb
= label_to_block (CASE_LABEL (taken_case
));
2211 e
= find_edge (bb
, dest_bb
);
2217 /* Return the CASE_LABEL_EXPR that SWITCH_EXPR will take for VAL.
2218 We can make optimal use here of the fact that the case labels are
2219 sorted: We can do a binary search for a case matching VAL. */
2222 find_case_label_for_value (tree switch_expr
, tree val
)
2224 tree vec
= SWITCH_LABELS (switch_expr
);
2225 size_t low
, high
, n
= TREE_VEC_LENGTH (vec
);
2226 tree default_case
= TREE_VEC_ELT (vec
, n
- 1);
2228 for (low
= -1, high
= n
- 1; high
- low
> 1; )
2230 size_t i
= (high
+ low
) / 2;
2231 tree t
= TREE_VEC_ELT (vec
, i
);
2234 /* Cache the result of comparing CASE_LOW and val. */
2235 cmp
= tree_int_cst_compare (CASE_LOW (t
), val
);
2242 if (CASE_HIGH (t
) == NULL
)
2244 /* A singe-valued case label. */
2250 /* A case range. We can only handle integer ranges. */
2251 if (cmp
<= 0 && tree_int_cst_compare (CASE_HIGH (t
), val
) >= 0)
2256 return default_case
;
2260 /* If all the PHI nodes in DEST have alternatives for E1 and E2 and
2261 those alternatives are equal in each of the PHI nodes, then return
2262 true, else return false. */
2265 phi_alternatives_equal (basic_block dest
, edge e1
, edge e2
)
2267 tree phi
, val1
, val2
;
2270 for (phi
= phi_nodes (dest
); phi
; phi
= PHI_CHAIN (phi
))
2272 n1
= phi_arg_from_edge (phi
, e1
);
2273 n2
= phi_arg_from_edge (phi
, e2
);
2275 gcc_assert (n1
>= 0);
2276 gcc_assert (n2
>= 0);
2278 val1
= PHI_ARG_DEF (phi
, n1
);
2279 val2
= PHI_ARG_DEF (phi
, n2
);
2281 if (!operand_equal_p (val1
, val2
, 0))
2289 /*---------------------------------------------------------------------------
2291 ---------------------------------------------------------------------------*/
2293 /* Dump tree-specific information of block BB to file OUTF. */
2296 tree_dump_bb (basic_block bb
, FILE *outf
, int indent
)
2298 dump_generic_bb (outf
, bb
, indent
, TDF_VOPS
);
2302 /* Dump a basic block on stderr. */
2305 debug_tree_bb (basic_block bb
)
2307 dump_bb (bb
, stderr
, 0);
2311 /* Dump basic block with index N on stderr. */
2314 debug_tree_bb_n (int n
)
2316 debug_tree_bb (BASIC_BLOCK (n
));
2317 return BASIC_BLOCK (n
);
2321 /* Dump the CFG on stderr.
2323 FLAGS are the same used by the tree dumping functions
2324 (see TDF_* in tree.h). */
2327 debug_tree_cfg (int flags
)
2329 dump_tree_cfg (stderr
, flags
);
2333 /* Dump the program showing basic block boundaries on the given FILE.
2335 FLAGS are the same used by the tree dumping functions (see TDF_* in
2339 dump_tree_cfg (FILE *file
, int flags
)
2341 if (flags
& TDF_DETAILS
)
2343 const char *funcname
2344 = lang_hooks
.decl_printable_name (current_function_decl
, 2);
2347 fprintf (file
, ";; Function %s\n\n", funcname
);
2348 fprintf (file
, ";; \n%d basic blocks, %d edges, last basic block %d.\n\n",
2349 n_basic_blocks
, n_edges
, last_basic_block
);
2351 brief_dump_cfg (file
);
2352 fprintf (file
, "\n");
2355 if (flags
& TDF_STATS
)
2356 dump_cfg_stats (file
);
2358 dump_function_to_file (current_function_decl
, file
, flags
| TDF_BLOCKS
);
2362 /* Dump CFG statistics on FILE. */
2365 dump_cfg_stats (FILE *file
)
2367 static long max_num_merged_labels
= 0;
2368 unsigned long size
, total
= 0;
2371 const char * const fmt_str
= "%-30s%-13s%12s\n";
2372 const char * const fmt_str_1
= "%-30s%13d%11lu%c\n";
2373 const char * const fmt_str_3
= "%-43s%11lu%c\n";
2374 const char *funcname
2375 = lang_hooks
.decl_printable_name (current_function_decl
, 2);
2378 fprintf (file
, "\nCFG Statistics for %s\n\n", funcname
);
2380 fprintf (file
, "---------------------------------------------------------\n");
2381 fprintf (file
, fmt_str
, "", " Number of ", "Memory");
2382 fprintf (file
, fmt_str
, "", " instances ", "used ");
2383 fprintf (file
, "---------------------------------------------------------\n");
2385 size
= n_basic_blocks
* sizeof (struct basic_block_def
);
2387 fprintf (file
, fmt_str_1
, "Basic blocks", n_basic_blocks
,
2388 SCALE (size
), LABEL (size
));
2392 n_edges
+= EDGE_COUNT (bb
->succs
);
2393 size
= n_edges
* sizeof (struct edge_def
);
2395 fprintf (file
, fmt_str_1
, "Edges", n_edges
, SCALE (size
), LABEL (size
));
2397 size
= n_basic_blocks
* sizeof (struct bb_ann_d
);
2399 fprintf (file
, fmt_str_1
, "Basic block annotations", n_basic_blocks
,
2400 SCALE (size
), LABEL (size
));
2402 fprintf (file
, "---------------------------------------------------------\n");
2403 fprintf (file
, fmt_str_3
, "Total memory used by CFG data", SCALE (total
),
2405 fprintf (file
, "---------------------------------------------------------\n");
2406 fprintf (file
, "\n");
2408 if (cfg_stats
.num_merged_labels
> max_num_merged_labels
)
2409 max_num_merged_labels
= cfg_stats
.num_merged_labels
;
2411 fprintf (file
, "Coalesced label blocks: %ld (Max so far: %ld)\n",
2412 cfg_stats
.num_merged_labels
, max_num_merged_labels
);
2414 fprintf (file
, "\n");
2418 /* Dump CFG statistics on stderr. Keep extern so that it's always
2419 linked in the final executable. */
2422 debug_cfg_stats (void)
2424 dump_cfg_stats (stderr
);
2428 /* Dump the flowgraph to a .vcg FILE. */
2431 tree_cfg2vcg (FILE *file
)
2436 const char *funcname
2437 = lang_hooks
.decl_printable_name (current_function_decl
, 2);
2439 /* Write the file header. */
2440 fprintf (file
, "graph: { title: \"%s\"\n", funcname
);
2441 fprintf (file
, "node: { title: \"ENTRY\" label: \"ENTRY\" }\n");
2442 fprintf (file
, "node: { title: \"EXIT\" label: \"EXIT\" }\n");
2444 /* Write blocks and edges. */
2445 FOR_EACH_EDGE (e
, ei
, ENTRY_BLOCK_PTR
->succs
)
2447 fprintf (file
, "edge: { sourcename: \"ENTRY\" targetname: \"%d\"",
2450 if (e
->flags
& EDGE_FAKE
)
2451 fprintf (file
, " linestyle: dotted priority: 10");
2453 fprintf (file
, " linestyle: solid priority: 100");
2455 fprintf (file
, " }\n");
2461 enum tree_code head_code
, end_code
;
2462 const char *head_name
, *end_name
;
2465 tree first
= first_stmt (bb
);
2466 tree last
= last_stmt (bb
);
2470 head_code
= TREE_CODE (first
);
2471 head_name
= tree_code_name
[head_code
];
2472 head_line
= get_lineno (first
);
2475 head_name
= "no-statement";
2479 end_code
= TREE_CODE (last
);
2480 end_name
= tree_code_name
[end_code
];
2481 end_line
= get_lineno (last
);
2484 end_name
= "no-statement";
2486 fprintf (file
, "node: { title: \"%d\" label: \"#%d\\n%s (%d)\\n%s (%d)\"}\n",
2487 bb
->index
, bb
->index
, head_name
, head_line
, end_name
,
2490 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
2492 if (e
->dest
== EXIT_BLOCK_PTR
)
2493 fprintf (file
, "edge: { sourcename: \"%d\" targetname: \"EXIT\"", bb
->index
);
2495 fprintf (file
, "edge: { sourcename: \"%d\" targetname: \"%d\"", bb
->index
, e
->dest
->index
);
2497 if (e
->flags
& EDGE_FAKE
)
2498 fprintf (file
, " priority: 10 linestyle: dotted");
2500 fprintf (file
, " priority: 100 linestyle: solid");
2502 fprintf (file
, " }\n");
2505 if (bb
->next_bb
!= EXIT_BLOCK_PTR
)
2509 fputs ("}\n\n", file
);
2514 /*---------------------------------------------------------------------------
2515 Miscellaneous helpers
2516 ---------------------------------------------------------------------------*/
2518 /* Return true if T represents a stmt that always transfers control. */
2521 is_ctrl_stmt (tree t
)
2523 return (TREE_CODE (t
) == COND_EXPR
2524 || TREE_CODE (t
) == SWITCH_EXPR
2525 || TREE_CODE (t
) == GOTO_EXPR
2526 || TREE_CODE (t
) == RETURN_EXPR
2527 || TREE_CODE (t
) == RESX_EXPR
);
2531 /* Return true if T is a statement that may alter the flow of control
2532 (e.g., a call to a non-returning function). */
2535 is_ctrl_altering_stmt (tree t
)
2540 call
= get_call_expr_in (t
);
2543 /* A non-pure/const CALL_EXPR alters flow control if the current
2544 function has nonlocal labels. */
2545 if (TREE_SIDE_EFFECTS (call
) && current_function_has_nonlocal_label
)
2548 /* A CALL_EXPR also alters control flow if it does not return. */
2549 if (call_expr_flags (call
) & ECF_NORETURN
)
2553 /* If a statement can throw, it alters control flow. */
2554 return tree_can_throw_internal (t
);
2558 /* Return true if T is a computed goto. */
2561 computed_goto_p (tree t
)
2563 return (TREE_CODE (t
) == GOTO_EXPR
2564 && TREE_CODE (GOTO_DESTINATION (t
)) != LABEL_DECL
);
2568 /* Checks whether EXPR is a simple local goto. */
2571 simple_goto_p (tree expr
)
2573 return (TREE_CODE (expr
) == GOTO_EXPR
2574 && TREE_CODE (GOTO_DESTINATION (expr
)) == LABEL_DECL
);
2578 /* Return true if T should start a new basic block. PREV_T is the
2579 statement preceding T. It is used when T is a label or a case label.
2580 Labels should only start a new basic block if their previous statement
2581 wasn't a label. Otherwise, sequence of labels would generate
2582 unnecessary basic blocks that only contain a single label. */
2585 stmt_starts_bb_p (tree t
, tree prev_t
)
2587 enum tree_code code
;
2592 /* LABEL_EXPRs start a new basic block only if the preceding
2593 statement wasn't a label of the same type. This prevents the
2594 creation of consecutive blocks that have nothing but a single
2596 code
= TREE_CODE (t
);
2597 if (code
== LABEL_EXPR
)
2599 /* Nonlocal and computed GOTO targets always start a new block. */
2600 if (code
== LABEL_EXPR
2601 && (DECL_NONLOCAL (LABEL_EXPR_LABEL (t
))
2602 || FORCED_LABEL (LABEL_EXPR_LABEL (t
))))
2605 if (prev_t
&& TREE_CODE (prev_t
) == code
)
2607 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (prev_t
)))
2610 cfg_stats
.num_merged_labels
++;
2621 /* Return true if T should end a basic block. */
2624 stmt_ends_bb_p (tree t
)
2626 return is_ctrl_stmt (t
) || is_ctrl_altering_stmt (t
);
2630 /* Add gotos that used to be represented implicitly in the CFG. */
2633 disband_implicit_edges (void)
2636 block_stmt_iterator last
;
2643 last
= bsi_last (bb
);
2644 stmt
= last_stmt (bb
);
2646 if (stmt
&& TREE_CODE (stmt
) == COND_EXPR
)
2648 /* Remove superfluous gotos from COND_EXPR branches. Moved
2649 from cfg_remove_useless_stmts here since it violates the
2650 invariants for tree--cfg correspondence and thus fits better
2651 here where we do it anyway. */
2652 e
= find_edge (bb
, bb
->next_bb
);
2655 if (e
->flags
& EDGE_TRUE_VALUE
)
2656 COND_EXPR_THEN (stmt
) = build_empty_stmt ();
2657 else if (e
->flags
& EDGE_FALSE_VALUE
)
2658 COND_EXPR_ELSE (stmt
) = build_empty_stmt ();
2661 e
->flags
|= EDGE_FALLTHRU
;
2667 if (stmt
&& TREE_CODE (stmt
) == RETURN_EXPR
)
2669 /* Remove the RETURN_EXPR if we may fall though to the exit
2671 gcc_assert (EDGE_COUNT (bb
->succs
) == 1);
2672 gcc_assert (EDGE_SUCC (bb
, 0)->dest
== EXIT_BLOCK_PTR
);
2674 if (bb
->next_bb
== EXIT_BLOCK_PTR
2675 && !TREE_OPERAND (stmt
, 0))
2678 EDGE_SUCC (bb
, 0)->flags
|= EDGE_FALLTHRU
;
2683 /* There can be no fallthru edge if the last statement is a control
2685 if (stmt
&& is_ctrl_stmt (stmt
))
2688 /* Find a fallthru edge and emit the goto if necessary. */
2689 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
2690 if (e
->flags
& EDGE_FALLTHRU
)
2693 if (!e
|| e
->dest
== bb
->next_bb
)
2696 gcc_assert (e
->dest
!= EXIT_BLOCK_PTR
);
2697 label
= tree_block_label (e
->dest
);
2699 stmt
= build1 (GOTO_EXPR
, void_type_node
, label
);
2700 #ifdef USE_MAPPED_LOCATION
2701 SET_EXPR_LOCATION (stmt
, e
->goto_locus
);
2703 SET_EXPR_LOCUS (stmt
, e
->goto_locus
);
2705 bsi_insert_after (&last
, stmt
, BSI_NEW_STMT
);
2706 e
->flags
&= ~EDGE_FALLTHRU
;
2710 /* Remove block annotations and other datastructures. */
2713 delete_tree_cfg_annotations (void)
2716 if (n_basic_blocks
> 0)
2717 free_blocks_annotations ();
2719 label_to_block_map
= NULL
;
2726 /* Return the first statement in basic block BB. */
2729 first_stmt (basic_block bb
)
2731 block_stmt_iterator i
= bsi_start (bb
);
2732 return !bsi_end_p (i
) ? bsi_stmt (i
) : NULL_TREE
;
2736 /* Return the last statement in basic block BB. */
2739 last_stmt (basic_block bb
)
2741 block_stmt_iterator b
= bsi_last (bb
);
2742 return !bsi_end_p (b
) ? bsi_stmt (b
) : NULL_TREE
;
2746 /* Return a pointer to the last statement in block BB. */
2749 last_stmt_ptr (basic_block bb
)
2751 block_stmt_iterator last
= bsi_last (bb
);
2752 return !bsi_end_p (last
) ? bsi_stmt_ptr (last
) : NULL
;
2756 /* Return the last statement of an otherwise empty block. Return NULL
2757 if the block is totally empty, or if it contains more than one
2761 last_and_only_stmt (basic_block bb
)
2763 block_stmt_iterator i
= bsi_last (bb
);
2769 last
= bsi_stmt (i
);
2774 /* Empty statements should no longer appear in the instruction stream.
2775 Everything that might have appeared before should be deleted by
2776 remove_useless_stmts, and the optimizers should just bsi_remove
2777 instead of smashing with build_empty_stmt.
2779 Thus the only thing that should appear here in a block containing
2780 one executable statement is a label. */
2781 prev
= bsi_stmt (i
);
2782 if (TREE_CODE (prev
) == LABEL_EXPR
)
2789 /* Mark BB as the basic block holding statement T. */
2792 set_bb_for_stmt (tree t
, basic_block bb
)
2794 if (TREE_CODE (t
) == PHI_NODE
)
2796 else if (TREE_CODE (t
) == STATEMENT_LIST
)
2798 tree_stmt_iterator i
;
2799 for (i
= tsi_start (t
); !tsi_end_p (i
); tsi_next (&i
))
2800 set_bb_for_stmt (tsi_stmt (i
), bb
);
2804 stmt_ann_t ann
= get_stmt_ann (t
);
2807 /* If the statement is a label, add the label to block-to-labels map
2808 so that we can speed up edge creation for GOTO_EXPRs. */
2809 if (TREE_CODE (t
) == LABEL_EXPR
)
2813 t
= LABEL_EXPR_LABEL (t
);
2814 uid
= LABEL_DECL_UID (t
);
2817 LABEL_DECL_UID (t
) = uid
= cfun
->last_label_uid
++;
2818 if (VARRAY_SIZE (label_to_block_map
) <= (unsigned) uid
)
2819 VARRAY_GROW (label_to_block_map
, 3 * uid
/ 2);
2822 /* We're moving an existing label. Make sure that we've
2823 removed it from the old block. */
2824 gcc_assert (!bb
|| !VARRAY_BB (label_to_block_map
, uid
));
2825 VARRAY_BB (label_to_block_map
, uid
) = bb
;
2830 /* Finds iterator for STMT. */
2832 extern block_stmt_iterator
2833 bsi_for_stmt (tree stmt
)
2835 block_stmt_iterator bsi
;
2837 for (bsi
= bsi_start (bb_for_stmt (stmt
)); !bsi_end_p (bsi
); bsi_next (&bsi
))
2838 if (bsi_stmt (bsi
) == stmt
)
2844 /* Insert statement (or statement list) T before the statement
2845 pointed-to by iterator I. M specifies how to update iterator I
2846 after insertion (see enum bsi_iterator_update). */
2849 bsi_insert_before (block_stmt_iterator
*i
, tree t
, enum bsi_iterator_update m
)
2851 set_bb_for_stmt (t
, i
->bb
);
2852 tsi_link_before (&i
->tsi
, t
, m
);
2857 /* Insert statement (or statement list) T after the statement
2858 pointed-to by iterator I. M specifies how to update iterator I
2859 after insertion (see enum bsi_iterator_update). */
2862 bsi_insert_after (block_stmt_iterator
*i
, tree t
, enum bsi_iterator_update m
)
2864 set_bb_for_stmt (t
, i
->bb
);
2865 tsi_link_after (&i
->tsi
, t
, m
);
2870 /* Remove the statement pointed to by iterator I. The iterator is updated
2871 to the next statement. */
2874 bsi_remove (block_stmt_iterator
*i
)
2876 tree t
= bsi_stmt (*i
);
2877 set_bb_for_stmt (t
, NULL
);
2878 tsi_delink (&i
->tsi
);
2882 /* Move the statement at FROM so it comes right after the statement at TO. */
2885 bsi_move_after (block_stmt_iterator
*from
, block_stmt_iterator
*to
)
2887 tree stmt
= bsi_stmt (*from
);
2889 bsi_insert_after (to
, stmt
, BSI_SAME_STMT
);
2893 /* Move the statement at FROM so it comes right before the statement at TO. */
2896 bsi_move_before (block_stmt_iterator
*from
, block_stmt_iterator
*to
)
2898 tree stmt
= bsi_stmt (*from
);
2900 bsi_insert_before (to
, stmt
, BSI_SAME_STMT
);
2904 /* Move the statement at FROM to the end of basic block BB. */
2907 bsi_move_to_bb_end (block_stmt_iterator
*from
, basic_block bb
)
2909 block_stmt_iterator last
= bsi_last (bb
);
2911 /* Have to check bsi_end_p because it could be an empty block. */
2912 if (!bsi_end_p (last
) && is_ctrl_stmt (bsi_stmt (last
)))
2913 bsi_move_before (from
, &last
);
2915 bsi_move_after (from
, &last
);
2919 /* Replace the contents of the statement pointed to by iterator BSI
2920 with STMT. If PRESERVE_EH_INFO is true, the exception handling
2921 information of the original statement is preserved. */
2924 bsi_replace (const block_stmt_iterator
*bsi
, tree stmt
, bool preserve_eh_info
)
2927 tree orig_stmt
= bsi_stmt (*bsi
);
2929 SET_EXPR_LOCUS (stmt
, EXPR_LOCUS (orig_stmt
));
2930 set_bb_for_stmt (stmt
, bsi
->bb
);
2932 /* Preserve EH region information from the original statement, if
2933 requested by the caller. */
2934 if (preserve_eh_info
)
2936 eh_region
= lookup_stmt_eh_region (orig_stmt
);
2938 add_stmt_to_eh_region (stmt
, eh_region
);
2941 *bsi_stmt_ptr (*bsi
) = stmt
;
2946 /* Insert the statement pointed-to by BSI into edge E. Every attempt
2947 is made to place the statement in an existing basic block, but
2948 sometimes that isn't possible. When it isn't possible, the edge is
2949 split and the statement is added to the new block.
2951 In all cases, the returned *BSI points to the correct location. The
2952 return value is true if insertion should be done after the location,
2953 or false if it should be done before the location. If new basic block
2954 has to be created, it is stored in *NEW_BB. */
2957 tree_find_edge_insert_loc (edge e
, block_stmt_iterator
*bsi
,
2958 basic_block
*new_bb
)
2960 basic_block dest
, src
;
2966 /* If the destination has one predecessor which has no PHI nodes,
2967 insert there. Except for the exit block.
2969 The requirement for no PHI nodes could be relaxed. Basically we
2970 would have to examine the PHIs to prove that none of them used
2971 the value set by the statement we want to insert on E. That
2972 hardly seems worth the effort. */
2973 if (EDGE_COUNT (dest
->preds
) == 1
2974 && ! phi_nodes (dest
)
2975 && dest
!= EXIT_BLOCK_PTR
)
2977 *bsi
= bsi_start (dest
);
2978 if (bsi_end_p (*bsi
))
2981 /* Make sure we insert after any leading labels. */
2982 tmp
= bsi_stmt (*bsi
);
2983 while (TREE_CODE (tmp
) == LABEL_EXPR
)
2986 if (bsi_end_p (*bsi
))
2988 tmp
= bsi_stmt (*bsi
);
2991 if (bsi_end_p (*bsi
))
2993 *bsi
= bsi_last (dest
);
3000 /* If the source has one successor, the edge is not abnormal and
3001 the last statement does not end a basic block, insert there.
3002 Except for the entry block. */
3004 if ((e
->flags
& EDGE_ABNORMAL
) == 0
3005 && EDGE_COUNT (src
->succs
) == 1
3006 && src
!= ENTRY_BLOCK_PTR
)
3008 *bsi
= bsi_last (src
);
3009 if (bsi_end_p (*bsi
))
3012 tmp
= bsi_stmt (*bsi
);
3013 if (!stmt_ends_bb_p (tmp
))
3016 /* Insert code just before returning the value. We may need to decompose
3017 the return in the case it contains non-trivial operand. */
3018 if (TREE_CODE (tmp
) == RETURN_EXPR
)
3020 tree op
= TREE_OPERAND (tmp
, 0);
3021 if (!is_gimple_val (op
))
3023 gcc_assert (TREE_CODE (op
) == MODIFY_EXPR
);
3024 bsi_insert_before (bsi
, op
, BSI_NEW_STMT
);
3025 TREE_OPERAND (tmp
, 0) = TREE_OPERAND (op
, 0);
3032 /* Otherwise, create a new basic block, and split this edge. */
3033 dest
= split_edge (e
);
3036 e
= EDGE_PRED (dest
, 0);
3041 /* This routine will commit all pending edge insertions, creating any new
3042 basic blocks which are necessary. */
3045 bsi_commit_edge_inserts (void)
3051 bsi_commit_one_edge_insert (EDGE_SUCC (ENTRY_BLOCK_PTR
, 0), NULL
);
3054 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
3055 bsi_commit_one_edge_insert (e
, NULL
);
3059 /* Commit insertions pending at edge E. If a new block is created, set NEW_BB
3060 to this block, otherwise set it to NULL. */
3063 bsi_commit_one_edge_insert (edge e
, basic_block
*new_bb
)
3067 if (PENDING_STMT (e
))
3069 block_stmt_iterator bsi
;
3070 tree stmt
= PENDING_STMT (e
);
3072 PENDING_STMT (e
) = NULL_TREE
;
3074 if (tree_find_edge_insert_loc (e
, &bsi
, new_bb
))
3075 bsi_insert_after (&bsi
, stmt
, BSI_NEW_STMT
);
3077 bsi_insert_before (&bsi
, stmt
, BSI_NEW_STMT
);
3082 /* Add STMT to the pending list of edge E. No actual insertion is
3083 made until a call to bsi_commit_edge_inserts () is made. */
3086 bsi_insert_on_edge (edge e
, tree stmt
)
3088 append_to_statement_list (stmt
, &PENDING_STMT (e
));
3091 /* Similar to bsi_insert_on_edge+bsi_commit_edge_inserts. If new block has to
3092 be created, it is returned. */
3095 bsi_insert_on_edge_immediate (edge e
, tree stmt
)
3097 block_stmt_iterator bsi
;
3098 basic_block new_bb
= NULL
;
3100 gcc_assert (!PENDING_STMT (e
));
3102 if (tree_find_edge_insert_loc (e
, &bsi
, &new_bb
))
3103 bsi_insert_after (&bsi
, stmt
, BSI_NEW_STMT
);
3105 bsi_insert_before (&bsi
, stmt
, BSI_NEW_STMT
);
3110 /*---------------------------------------------------------------------------
3111 Tree specific functions for CFG manipulation
3112 ---------------------------------------------------------------------------*/
3114 /* Reinstall those PHI arguments queued in OLD_EDGE to NEW_EDGE. */
3117 reinstall_phi_args (edge new_edge
, edge old_edge
)
3121 if (!PENDING_STMT (old_edge
))
3124 for (var
= PENDING_STMT (old_edge
), phi
= phi_nodes (new_edge
->dest
);
3126 var
= TREE_CHAIN (var
), phi
= PHI_CHAIN (phi
))
3128 tree result
= TREE_PURPOSE (var
);
3129 tree arg
= TREE_VALUE (var
);
3131 gcc_assert (result
== PHI_RESULT (phi
));
3133 add_phi_arg (&phi
, arg
, new_edge
);
3136 PENDING_STMT (old_edge
) = NULL
;
3139 /* Split a (typically critical) edge EDGE_IN. Return the new block.
3140 Abort on abnormal edges. */
3143 tree_split_edge (edge edge_in
)
3145 basic_block new_bb
, after_bb
, dest
, src
;
3149 /* Abnormal edges cannot be split. */
3150 gcc_assert (!(edge_in
->flags
& EDGE_ABNORMAL
));
3153 dest
= edge_in
->dest
;
3155 /* Place the new block in the block list. Try to keep the new block
3156 near its "logical" location. This is of most help to humans looking
3157 at debugging dumps. */
3158 FOR_EACH_EDGE (e
, ei
, dest
->preds
)
3159 if (e
->src
->next_bb
== dest
)
3162 after_bb
= dest
->prev_bb
;
3164 after_bb
= edge_in
->src
;
3166 new_bb
= create_empty_bb (after_bb
);
3167 new_bb
->frequency
= EDGE_FREQUENCY (edge_in
);
3168 new_bb
->count
= edge_in
->count
;
3169 new_edge
= make_edge (new_bb
, dest
, EDGE_FALLTHRU
);
3170 new_edge
->probability
= REG_BR_PROB_BASE
;
3171 new_edge
->count
= edge_in
->count
;
3173 e
= redirect_edge_and_branch (edge_in
, new_bb
);
3175 reinstall_phi_args (new_edge
, e
);
3181 /* Return true when BB has label LABEL in it. */
3184 has_label_p (basic_block bb
, tree label
)
3186 block_stmt_iterator bsi
;
3188 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
3190 tree stmt
= bsi_stmt (bsi
);
3192 if (TREE_CODE (stmt
) != LABEL_EXPR
)
3194 if (LABEL_EXPR_LABEL (stmt
) == label
)
3201 /* Callback for walk_tree, check that all elements with address taken are
3202 properly noticed as such. */
3205 verify_expr (tree
*tp
, int *walk_subtrees
, void *data ATTRIBUTE_UNUSED
)
3212 /* Check operand N for being valid GIMPLE and give error MSG if not.
3213 We check for constants explicitly since they are not considered
3214 gimple invariants if they overflowed. */
3215 #define CHECK_OP(N, MSG) \
3216 do { if (!CONSTANT_CLASS_P (TREE_OPERAND (t, N)) \
3217 && !is_gimple_val (TREE_OPERAND (t, N))) \
3218 { error (MSG); return TREE_OPERAND (t, N); }} while (0)
3220 switch (TREE_CODE (t
))
3223 if (SSA_NAME_IN_FREE_LIST (t
))
3225 error ("SSA name in freelist but still referenced");
3231 x
= TREE_OPERAND (t
, 0);
3232 if (TREE_CODE (x
) == BIT_FIELD_REF
3233 && is_gimple_reg (TREE_OPERAND (x
, 0)))
3235 error ("GIMPLE register modified with BIT_FIELD_REF");
3241 /* Skip any references (they will be checked when we recurse down the
3242 tree) and ensure that any variable used as a prefix is marked
3244 for (x
= TREE_OPERAND (t
, 0);
3245 (handled_component_p (x
)
3246 || TREE_CODE (x
) == REALPART_EXPR
3247 || TREE_CODE (x
) == IMAGPART_EXPR
);
3248 x
= TREE_OPERAND (x
, 0))
3251 if (TREE_CODE (x
) != VAR_DECL
&& TREE_CODE (x
) != PARM_DECL
)
3253 if (!TREE_ADDRESSABLE (x
))
3255 error ("address taken, but ADDRESSABLE bit not set");
3261 x
= COND_EXPR_COND (t
);
3262 if (TREE_CODE (TREE_TYPE (x
)) != BOOLEAN_TYPE
)
3264 error ("non-boolean used in condition");
3271 case FIX_TRUNC_EXPR
:
3273 case FIX_FLOOR_EXPR
:
3274 case FIX_ROUND_EXPR
:
3279 case NON_LVALUE_EXPR
:
3280 case TRUTH_NOT_EXPR
:
3281 CHECK_OP (0, "Invalid operand to unary operator");
3288 case ARRAY_RANGE_REF
:
3290 case VIEW_CONVERT_EXPR
:
3291 /* We have a nest of references. Verify that each of the operands
3292 that determine where to reference is either a constant or a variable,
3293 verify that the base is valid, and then show we've already checked
3295 while (TREE_CODE (t
) == REALPART_EXPR
|| TREE_CODE (t
) == IMAGPART_EXPR
3296 || handled_component_p (t
))
3298 if (TREE_CODE (t
) == COMPONENT_REF
&& TREE_OPERAND (t
, 2))
3299 CHECK_OP (2, "Invalid COMPONENT_REF offset operator");
3300 else if (TREE_CODE (t
) == ARRAY_REF
3301 || TREE_CODE (t
) == ARRAY_RANGE_REF
)
3303 CHECK_OP (1, "Invalid array index.");
3304 if (TREE_OPERAND (t
, 2))
3305 CHECK_OP (2, "Invalid array lower bound.");
3306 if (TREE_OPERAND (t
, 3))
3307 CHECK_OP (3, "Invalid array stride.");
3309 else if (TREE_CODE (t
) == BIT_FIELD_REF
)
3311 CHECK_OP (1, "Invalid operand to BIT_FIELD_REF");
3312 CHECK_OP (2, "Invalid operand to BIT_FIELD_REF");
3315 t
= TREE_OPERAND (t
, 0);
3318 if (!CONSTANT_CLASS_P (t
) && !is_gimple_lvalue (t
))
3320 error ("Invalid reference prefix.");
3332 case UNORDERED_EXPR
:
3343 case TRUNC_DIV_EXPR
:
3345 case FLOOR_DIV_EXPR
:
3346 case ROUND_DIV_EXPR
:
3347 case TRUNC_MOD_EXPR
:
3349 case FLOOR_MOD_EXPR
:
3350 case ROUND_MOD_EXPR
:
3352 case EXACT_DIV_EXPR
:
3362 CHECK_OP (0, "Invalid operand to binary operator");
3363 CHECK_OP (1, "Invalid operand to binary operator");
3375 /* Verify STMT, return true if STMT is not in GIMPLE form.
3376 TODO: Implement type checking. */
3379 verify_stmt (tree stmt
, bool last_in_block
)
3383 if (!is_gimple_stmt (stmt
))
3385 error ("Is not a valid GIMPLE statement.");
3389 addr
= walk_tree (&stmt
, verify_expr
, NULL
, NULL
);
3392 debug_generic_stmt (addr
);
3396 /* If the statement is marked as part of an EH region, then it is
3397 expected that the statement could throw. Verify that when we
3398 have optimizations that simplify statements such that we prove
3399 that they cannot throw, that we update other data structures
3401 if (lookup_stmt_eh_region (stmt
) >= 0)
3403 if (!tree_could_throw_p (stmt
))
3405 error ("Statement marked for throw, but doesn%'t.");
3408 if (!last_in_block
&& tree_can_throw_internal (stmt
))
3410 error ("Statement marked for throw in middle of block.");
3418 debug_generic_stmt (stmt
);
3423 /* Return true when the T can be shared. */
3426 tree_node_can_be_shared (tree t
)
3428 if (IS_TYPE_OR_DECL_P (t
)
3429 /* We check for constants explicitly since they are not considered
3430 gimple invariants if they overflowed. */
3431 || CONSTANT_CLASS_P (t
)
3432 || is_gimple_min_invariant (t
)
3433 || TREE_CODE (t
) == SSA_NAME
)
3436 if (TREE_CODE (t
) == CASE_LABEL_EXPR
)
3439 while (((TREE_CODE (t
) == ARRAY_REF
|| TREE_CODE (t
) == ARRAY_RANGE_REF
)
3440 /* We check for constants explicitly since they are not considered
3441 gimple invariants if they overflowed. */
3442 && (CONSTANT_CLASS_P (TREE_OPERAND (t
, 1))
3443 || is_gimple_min_invariant (TREE_OPERAND (t
, 1))))
3444 || (TREE_CODE (t
) == COMPONENT_REF
3445 || TREE_CODE (t
) == REALPART_EXPR
3446 || TREE_CODE (t
) == IMAGPART_EXPR
))
3447 t
= TREE_OPERAND (t
, 0);
3456 /* Called via walk_trees. Verify tree sharing. */
3459 verify_node_sharing (tree
* tp
, int *walk_subtrees
, void *data
)
3461 htab_t htab
= (htab_t
) data
;
3464 if (tree_node_can_be_shared (*tp
))
3466 *walk_subtrees
= false;
3470 slot
= htab_find_slot (htab
, *tp
, INSERT
);
3479 /* Verify the GIMPLE statement chain. */
3485 block_stmt_iterator bsi
;
3490 timevar_push (TV_TREE_STMT_VERIFY
);
3491 htab
= htab_create (37, htab_hash_pointer
, htab_eq_pointer
, NULL
);
3498 for (phi
= phi_nodes (bb
); phi
; phi
= PHI_CHAIN (phi
))
3500 int phi_num_args
= PHI_NUM_ARGS (phi
);
3502 for (i
= 0; i
< phi_num_args
; i
++)
3504 tree t
= PHI_ARG_DEF (phi
, i
);
3507 /* Addressable variables do have SSA_NAMEs but they
3508 are not considered gimple values. */
3509 if (TREE_CODE (t
) != SSA_NAME
3510 && TREE_CODE (t
) != FUNCTION_DECL
3511 && !is_gimple_val (t
))
3513 error ("PHI def is not a GIMPLE value");
3514 debug_generic_stmt (phi
);
3515 debug_generic_stmt (t
);
3519 addr
= walk_tree (&t
, verify_expr
, NULL
, NULL
);
3522 debug_generic_stmt (addr
);
3526 addr
= walk_tree (&t
, verify_node_sharing
, htab
, NULL
);
3529 error ("Incorrect sharing of tree nodes");
3530 debug_generic_stmt (phi
);
3531 debug_generic_stmt (addr
);
3537 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); )
3539 tree stmt
= bsi_stmt (bsi
);
3541 err
|= verify_stmt (stmt
, bsi_end_p (bsi
));
3542 addr
= walk_tree (&stmt
, verify_node_sharing
, htab
, NULL
);
3545 error ("Incorrect sharing of tree nodes");
3546 debug_generic_stmt (stmt
);
3547 debug_generic_stmt (addr
);
3554 internal_error ("verify_stmts failed.");
3557 timevar_pop (TV_TREE_STMT_VERIFY
);
3561 /* Verifies that the flow information is OK. */
3564 tree_verify_flow_info (void)
3568 block_stmt_iterator bsi
;
3573 if (ENTRY_BLOCK_PTR
->stmt_list
)
3575 error ("ENTRY_BLOCK has a statement list associated with it\n");
3579 if (EXIT_BLOCK_PTR
->stmt_list
)
3581 error ("EXIT_BLOCK has a statement list associated with it\n");
3585 FOR_EACH_EDGE (e
, ei
, EXIT_BLOCK_PTR
->preds
)
3586 if (e
->flags
& EDGE_FALLTHRU
)
3588 error ("Fallthru to exit from bb %d\n", e
->src
->index
);
3594 bool found_ctrl_stmt
= false;
3596 /* Skip labels on the start of basic block. */
3597 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
3599 if (TREE_CODE (bsi_stmt (bsi
)) != LABEL_EXPR
)
3602 if (label_to_block (LABEL_EXPR_LABEL (bsi_stmt (bsi
))) != bb
)
3604 tree stmt
= bsi_stmt (bsi
);
3605 error ("Label %s to block does not match in bb %d\n",
3606 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt
))),
3611 if (decl_function_context (LABEL_EXPR_LABEL (bsi_stmt (bsi
)))
3612 != current_function_decl
)
3614 tree stmt
= bsi_stmt (bsi
);
3615 error ("Label %s has incorrect context in bb %d\n",
3616 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt
))),
3622 /* Verify that body of basic block BB is free of control flow. */
3623 for (; !bsi_end_p (bsi
); bsi_next (&bsi
))
3625 tree stmt
= bsi_stmt (bsi
);
3627 if (found_ctrl_stmt
)
3629 error ("Control flow in the middle of basic block %d\n",
3634 if (stmt_ends_bb_p (stmt
))
3635 found_ctrl_stmt
= true;
3637 if (TREE_CODE (stmt
) == LABEL_EXPR
)
3639 error ("Label %s in the middle of basic block %d\n",
3640 IDENTIFIER_POINTER (DECL_NAME (stmt
)),
3645 bsi
= bsi_last (bb
);
3646 if (bsi_end_p (bsi
))
3649 stmt
= bsi_stmt (bsi
);
3651 if (is_ctrl_stmt (stmt
))
3653 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
3654 if (e
->flags
& EDGE_FALLTHRU
)
3656 error ("Fallthru edge after a control statement in bb %d \n",
3662 switch (TREE_CODE (stmt
))
3668 if (TREE_CODE (COND_EXPR_THEN (stmt
)) != GOTO_EXPR
3669 || TREE_CODE (COND_EXPR_ELSE (stmt
)) != GOTO_EXPR
)
3671 error ("Structured COND_EXPR at the end of bb %d\n", bb
->index
);
3675 extract_true_false_edges_from_block (bb
, &true_edge
, &false_edge
);
3677 if (!true_edge
|| !false_edge
3678 || !(true_edge
->flags
& EDGE_TRUE_VALUE
)
3679 || !(false_edge
->flags
& EDGE_FALSE_VALUE
)
3680 || (true_edge
->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
))
3681 || (false_edge
->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
))
3682 || EDGE_COUNT (bb
->succs
) >= 3)
3684 error ("Wrong outgoing edge flags at end of bb %d\n",
3689 if (!has_label_p (true_edge
->dest
,
3690 GOTO_DESTINATION (COND_EXPR_THEN (stmt
))))
3692 error ("%<then%> label does not match edge at end of bb %d\n",
3697 if (!has_label_p (false_edge
->dest
,
3698 GOTO_DESTINATION (COND_EXPR_ELSE (stmt
))))
3700 error ("%<else%> label does not match edge at end of bb %d\n",
3708 if (simple_goto_p (stmt
))
3710 error ("Explicit goto at end of bb %d\n", bb
->index
);
3715 /* FIXME. We should double check that the labels in the
3716 destination blocks have their address taken. */
3717 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
3718 if ((e
->flags
& (EDGE_FALLTHRU
| EDGE_TRUE_VALUE
3719 | EDGE_FALSE_VALUE
))
3720 || !(e
->flags
& EDGE_ABNORMAL
))
3722 error ("Wrong outgoing edge flags at end of bb %d\n",
3730 if (EDGE_COUNT (bb
->succs
) != 1
3731 || (EDGE_SUCC (bb
, 0)->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
3732 | EDGE_TRUE_VALUE
| EDGE_FALSE_VALUE
)))
3734 error ("Wrong outgoing edge flags at end of bb %d\n", bb
->index
);
3737 if (EDGE_SUCC (bb
, 0)->dest
!= EXIT_BLOCK_PTR
)
3739 error ("Return edge does not point to exit in bb %d\n",
3752 vec
= SWITCH_LABELS (stmt
);
3753 n
= TREE_VEC_LENGTH (vec
);
3755 /* Mark all the destination basic blocks. */
3756 for (i
= 0; i
< n
; ++i
)
3758 tree lab
= CASE_LABEL (TREE_VEC_ELT (vec
, i
));
3759 basic_block label_bb
= label_to_block (lab
);
3761 gcc_assert (!label_bb
->aux
|| label_bb
->aux
== (void *)1);
3762 label_bb
->aux
= (void *)1;
3765 /* Verify that the case labels are sorted. */
3766 prev
= TREE_VEC_ELT (vec
, 0);
3767 for (i
= 1; i
< n
- 1; ++i
)
3769 tree c
= TREE_VEC_ELT (vec
, i
);
3772 error ("Found default case not at end of case vector");
3776 if (! tree_int_cst_lt (CASE_LOW (prev
), CASE_LOW (c
)))
3778 error ("Case labels not sorted:\n ");
3779 print_generic_expr (stderr
, prev
, 0);
3780 fprintf (stderr
," is greater than ");
3781 print_generic_expr (stderr
, c
, 0);
3782 fprintf (stderr
," but comes before it.\n");
3787 if (CASE_LOW (TREE_VEC_ELT (vec
, n
- 1)))
3789 error ("No default case found at end of case vector");
3793 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
3797 error ("Extra outgoing edge %d->%d\n",
3798 bb
->index
, e
->dest
->index
);
3801 e
->dest
->aux
= (void *)2;
3802 if ((e
->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
3803 | EDGE_TRUE_VALUE
| EDGE_FALSE_VALUE
)))
3805 error ("Wrong outgoing edge flags at end of bb %d\n",
3811 /* Check that we have all of them. */
3812 for (i
= 0; i
< n
; ++i
)
3814 tree lab
= CASE_LABEL (TREE_VEC_ELT (vec
, i
));
3815 basic_block label_bb
= label_to_block (lab
);
3817 if (label_bb
->aux
!= (void *)2)
3819 error ("Missing edge %i->%i\n",
3820 bb
->index
, label_bb
->index
);
3825 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
3826 e
->dest
->aux
= (void *)0;
3833 if (dom_computed
[CDI_DOMINATORS
] >= DOM_NO_FAST_QUERY
)
3834 verify_dominators (CDI_DOMINATORS
);
3840 /* Updates phi nodes after creating a forwarder block joined
3841 by edge FALLTHRU. */
3844 tree_make_forwarder_block (edge fallthru
)
3848 basic_block dummy
, bb
;
3849 tree phi
, new_phi
, var
;
3851 dummy
= fallthru
->src
;
3852 bb
= fallthru
->dest
;
3854 if (EDGE_COUNT (bb
->preds
) == 1)
3857 /* If we redirected a branch we must create new phi nodes at the
3859 for (phi
= phi_nodes (dummy
); phi
; phi
= PHI_CHAIN (phi
))
3861 var
= PHI_RESULT (phi
);
3862 new_phi
= create_phi_node (var
, bb
);
3863 SSA_NAME_DEF_STMT (var
) = new_phi
;
3864 SET_PHI_RESULT (phi
, make_ssa_name (SSA_NAME_VAR (var
), phi
));
3865 add_phi_arg (&new_phi
, PHI_RESULT (phi
), fallthru
);
3868 /* Ensure that the PHI node chain is in the same order. */
3869 set_phi_nodes (bb
, phi_reverse (phi_nodes (bb
)));
3871 /* Add the arguments we have stored on edges. */
3872 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
3877 flush_pending_stmts (e
);
3882 /* Return true if basic block BB does nothing except pass control
3883 flow to another block and that we can safely insert a label at
3884 the start of the successor block.
3886 As a precondition, we require that BB be not equal to
3890 tree_forwarder_block_p (basic_block bb
)
3892 block_stmt_iterator bsi
;
3894 /* BB must have a single outgoing edge. */
3895 if (EDGE_COUNT (bb
->succs
) != 1
3896 /* BB can not have any PHI nodes. This could potentially be
3897 relaxed early in compilation if we re-rewrote the variables
3898 appearing in any PHI nodes in forwarder blocks. */
3900 /* BB may not be a predecessor of EXIT_BLOCK_PTR. */
3901 || EDGE_SUCC (bb
, 0)->dest
== EXIT_BLOCK_PTR
3902 /* BB may not have an abnormal outgoing edge. */
3903 || (EDGE_SUCC (bb
, 0)->flags
& EDGE_ABNORMAL
))
3907 gcc_assert (bb
!= ENTRY_BLOCK_PTR
);
3910 /* Now walk through the statements. We can ignore labels, anything else
3911 means this is not a forwarder block. */
3912 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
3914 tree stmt
= bsi_stmt (bsi
);
3916 switch (TREE_CODE (stmt
))
3919 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt
)))
3928 if (find_edge (ENTRY_BLOCK_PTR
, bb
))
3934 /* Thread jumps from BB. */
3937 thread_jumps_from_bb (basic_block bb
)
3941 bool retval
= false;
3943 /* Examine each of our block's successors to see if it is
3945 for (ei
= ei_start (bb
->succs
); (e
= ei_safe_edge (ei
)); )
3950 basic_block dest
, tmp
, curr
, old_dest
;
3954 /* If the edge is abnormal or its destination is not
3955 forwardable, then there's nothing to do. */
3956 if ((e
->flags
& EDGE_ABNORMAL
)
3957 || !bb_ann (e
->dest
)->forwardable
)
3963 /* Now walk through as many forwarder blocks as possible to find
3964 the ultimate destination we want to thread our jump to. */
3965 last
= EDGE_SUCC (e
->dest
, 0);
3966 bb_ann (e
->dest
)->forwardable
= 0;
3967 for (dest
= EDGE_SUCC (e
->dest
, 0)->dest
;
3968 bb_ann (dest
)->forwardable
;
3969 last
= EDGE_SUCC (dest
, 0),
3970 dest
= EDGE_SUCC (dest
, 0)->dest
)
3971 bb_ann (dest
)->forwardable
= 0;
3973 /* Reset the forwardable marks to 1. */
3976 tmp
= EDGE_SUCC (tmp
, 0)->dest
)
3977 bb_ann (tmp
)->forwardable
= 1;
3979 if (dest
== e
->dest
)
3985 old
= find_edge (bb
, dest
);
3988 /* If there already is an edge, check whether the values in
3989 phi nodes differ. */
3990 if (!phi_alternatives_equal (dest
, last
, old
))
3992 /* The previous block is forwarder. Redirect our jump
3993 to that target instead since we know it has no PHI
3994 nodes that will need updating. */
3997 /* That might mean that no forwarding at all is
3999 if (dest
== e
->dest
)
4005 old
= find_edge (bb
, dest
);
4009 /* Perform the redirection. */
4012 freq
= EDGE_FREQUENCY (e
);
4014 e
= redirect_edge_and_branch (e
, dest
);
4016 /* Update the profile. */
4017 if (profile_status
!= PROFILE_ABSENT
)
4018 for (curr
= old_dest
;
4020 curr
= EDGE_SUCC (curr
, 0)->dest
)
4022 curr
->frequency
-= freq
;
4023 if (curr
->frequency
< 0)
4024 curr
->frequency
= 0;
4025 curr
->count
-= count
;
4026 if (curr
->count
< 0)
4028 EDGE_SUCC (curr
, 0)->count
-= count
;
4029 if (EDGE_SUCC (curr
, 0)->count
< 0)
4030 EDGE_SUCC (curr
, 0)->count
= 0;
4035 /* Update PHI nodes. We know that the new argument should
4036 have the same value as the argument associated with LAST.
4037 Otherwise we would have changed our target block
4039 for (phi
= phi_nodes (dest
); phi
; phi
= PHI_CHAIN (phi
))
4041 arg
= phi_arg_from_edge (phi
, last
);
4042 gcc_assert (arg
>= 0);
4043 add_phi_arg (&phi
, PHI_ARG_DEF (phi
, arg
), e
);
4047 /* Remove the unreachable blocks (observe that if all blocks
4048 were reachable before, only those in the path we threaded
4049 over and did not have any predecessor outside of the path
4050 become unreachable). */
4051 for (; old_dest
!= dest
; old_dest
= tmp
)
4053 tmp
= EDGE_SUCC (old_dest
, 0)->dest
;
4055 if (EDGE_COUNT (old_dest
->preds
) > 0)
4058 delete_basic_block (old_dest
);
4061 /* Update the dominators. */
4062 if (dom_info_available_p (CDI_DOMINATORS
))
4064 /* If the dominator of the destination was in the
4065 path, set its dominator to the start of the
4067 if (get_immediate_dominator (CDI_DOMINATORS
, old_dest
) == NULL
)
4068 set_immediate_dominator (CDI_DOMINATORS
, old_dest
, bb
);
4070 /* Now proceed like if we forwarded just over one edge at a
4071 time. Algorithm for forwarding edge S --> A over
4072 edge A --> B then is
4075 && !dominated_by (S, B))
4076 idom (B) = idom (A);
4077 recount_idom (A); */
4079 for (; old_dest
!= dest
; old_dest
= tmp
)
4083 tmp
= EDGE_SUCC (old_dest
, 0)->dest
;
4085 if (get_immediate_dominator (CDI_DOMINATORS
, tmp
) == old_dest
4086 && !dominated_by_p (CDI_DOMINATORS
, bb
, tmp
))
4088 dom
= get_immediate_dominator (CDI_DOMINATORS
, old_dest
);
4089 set_immediate_dominator (CDI_DOMINATORS
, tmp
, dom
);
4092 dom
= recount_dominator (CDI_DOMINATORS
, old_dest
);
4093 set_immediate_dominator (CDI_DOMINATORS
, old_dest
, dom
);
4102 /* Thread jumps over empty statements.
4104 This code should _not_ thread over obviously equivalent conditions
4105 as that requires nontrivial updates to the SSA graph.
4107 As a precondition, we require that all basic blocks be reachable.
4108 That is, there should be no opportunities left for
4109 delete_unreachable_blocks. */
4115 bool retval
= false;
4116 basic_block
*worklist
= xmalloc (sizeof (basic_block
) * last_basic_block
);
4117 basic_block
*current
= worklist
;
4121 bb_ann (bb
)->forwardable
= tree_forwarder_block_p (bb
);
4122 bb
->flags
&= ~BB_VISITED
;
4125 /* We pretend to have ENTRY_BLOCK_PTR in WORKLIST. This way,
4126 ENTRY_BLOCK_PTR will never be entered into WORKLIST. */
4127 ENTRY_BLOCK_PTR
->flags
|= BB_VISITED
;
4129 /* Initialize WORKLIST by putting non-forwarder blocks that
4130 immediately precede forwarder blocks because those are the ones
4131 that we know we can thread jumps from. We use BB_VISITED to
4132 indicate whether a given basic block is in WORKLIST or not,
4133 thereby avoiding duplicates in WORKLIST. */
4139 /* We are not interested in finding non-forwarder blocks
4140 directly. We want to find non-forwarder blocks as
4141 predecessors of a forwarder block. */
4142 if (!bb_ann (bb
)->forwardable
)
4145 /* Now we know BB is a forwarder block. Visit each of its
4146 incoming edges and add to WORKLIST all non-forwarder blocks
4147 among BB's predecessors. */
4148 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
4150 /* We don't want to put a duplicate into WORKLIST. */
4151 if ((e
->src
->flags
& BB_VISITED
) == 0
4152 /* We are not interested in threading jumps from a forwarder
4154 && !bb_ann (e
->src
)->forwardable
)
4156 e
->src
->flags
|= BB_VISITED
;
4157 *current
++ = e
->src
;
4162 /* Now let's drain WORKLIST. */
4163 while (worklist
!= current
)
4167 /* BB is no longer in WORKLIST, so clear BB_VISITED. */
4168 bb
->flags
&= ~BB_VISITED
;
4170 if (thread_jumps_from_bb (bb
))
4174 if (tree_forwarder_block_p (bb
))
4179 bb_ann (bb
)->forwardable
= true;
4181 /* Attempts to thread through BB may have been blocked
4182 because BB was not a forwarder block before. Now
4183 that BB is a forwarder block, we should revisit BB's
4185 FOR_EACH_EDGE (f
, ej
, bb
->preds
)
4187 /* We don't want to put a duplicate into WORKLIST. */
4188 if ((f
->src
->flags
& BB_VISITED
) == 0
4189 /* We are not interested in threading jumps from a
4191 && !bb_ann (f
->src
)->forwardable
)
4193 f
->src
->flags
|= BB_VISITED
;
4194 *current
++ = f
->src
;
4201 ENTRY_BLOCK_PTR
->flags
&= ~BB_VISITED
;
4209 /* Return a non-special label in the head of basic block BLOCK.
4210 Create one if it doesn't exist. */
4213 tree_block_label (basic_block bb
)
4215 block_stmt_iterator i
, s
= bsi_start (bb
);
4219 for (i
= s
; !bsi_end_p (i
); first
= false, bsi_next (&i
))
4221 stmt
= bsi_stmt (i
);
4222 if (TREE_CODE (stmt
) != LABEL_EXPR
)
4224 label
= LABEL_EXPR_LABEL (stmt
);
4225 if (!DECL_NONLOCAL (label
))
4228 bsi_move_before (&i
, &s
);
4233 label
= create_artificial_label ();
4234 stmt
= build1 (LABEL_EXPR
, void_type_node
, label
);
4235 bsi_insert_before (&s
, stmt
, BSI_NEW_STMT
);
4240 /* Attempt to perform edge redirection by replacing a possibly complex
4241 jump instruction by a goto or by removing the jump completely.
4242 This can apply only if all edges now point to the same block. The
4243 parameters and return values are equivalent to
4244 redirect_edge_and_branch. */
4247 tree_try_redirect_by_replacing_jump (edge e
, basic_block target
)
4249 basic_block src
= e
->src
;
4250 block_stmt_iterator b
;
4253 /* We can replace or remove a complex jump only when we have exactly
4255 if (EDGE_COUNT (src
->succs
) != 2
4256 /* Verify that all targets will be TARGET. Specifically, the
4257 edge that is not E must also go to TARGET. */
4258 || EDGE_SUCC (src
, EDGE_SUCC (src
, 0) == e
)->dest
!= target
)
4264 stmt
= bsi_stmt (b
);
4266 if (TREE_CODE (stmt
) == COND_EXPR
4267 || TREE_CODE (stmt
) == SWITCH_EXPR
)
4270 e
= ssa_redirect_edge (e
, target
);
4271 e
->flags
= EDGE_FALLTHRU
;
4279 /* Redirect E to DEST. Return NULL on failure. Otherwise, return the
4280 edge representing the redirected branch. */
4283 tree_redirect_edge_and_branch (edge e
, basic_block dest
)
4285 basic_block bb
= e
->src
;
4286 block_stmt_iterator bsi
;
4290 if (e
->flags
& (EDGE_ABNORMAL_CALL
| EDGE_EH
))
4293 if (e
->src
!= ENTRY_BLOCK_PTR
4294 && (ret
= tree_try_redirect_by_replacing_jump (e
, dest
)))
4297 if (e
->dest
== dest
)
4300 label
= tree_block_label (dest
);
4302 bsi
= bsi_last (bb
);
4303 stmt
= bsi_end_p (bsi
) ? NULL
: bsi_stmt (bsi
);
4305 switch (stmt
? TREE_CODE (stmt
) : ERROR_MARK
)
4308 stmt
= (e
->flags
& EDGE_TRUE_VALUE
4309 ? COND_EXPR_THEN (stmt
)
4310 : COND_EXPR_ELSE (stmt
));
4311 GOTO_DESTINATION (stmt
) = label
;
4315 /* No non-abnormal edges should lead from a non-simple goto, and
4316 simple ones should be represented implicitly. */
4321 tree cases
= get_cases_for_edge (e
, stmt
);
4322 edge e2
= find_edge (e
->src
, dest
);
4324 /* If we have a list of cases associated with E, then use it
4325 as it's a lot faster than walking the entire case vector. */
4334 CASE_LABEL (cases
) = label
;
4335 cases
= TREE_CHAIN (cases
);
4338 /* If there was already an edge in the CFG, then we need
4339 to move all the cases associated with E to E2. */
4342 tree cases2
= get_cases_for_edge (e2
, stmt
);
4344 TREE_CHAIN (last
) = TREE_CHAIN (cases2
);
4345 TREE_CHAIN (cases2
) = first
;
4350 tree vec
= SWITCH_LABELS (stmt
);
4351 size_t i
, n
= TREE_VEC_LENGTH (vec
);
4353 for (i
= 0; i
< n
; i
++)
4355 tree elt
= TREE_VEC_ELT (vec
, i
);
4357 if (label_to_block (CASE_LABEL (elt
)) == e
->dest
)
4358 CASE_LABEL (elt
) = label
;
4367 e
->flags
|= EDGE_FALLTHRU
;
4371 /* Otherwise it must be a fallthru edge, and we don't need to
4372 do anything besides redirecting it. */
4373 gcc_assert (e
->flags
& EDGE_FALLTHRU
);
4377 /* Update/insert PHI nodes as necessary. */
4379 /* Now update the edges in the CFG. */
4380 e
= ssa_redirect_edge (e
, dest
);
4386 /* Simple wrapper, as we can always redirect fallthru edges. */
4389 tree_redirect_edge_and_branch_force (edge e
, basic_block dest
)
4391 e
= tree_redirect_edge_and_branch (e
, dest
);
4398 /* Splits basic block BB after statement STMT (but at least after the
4399 labels). If STMT is NULL, BB is split just after the labels. */
4402 tree_split_block (basic_block bb
, void *stmt
)
4404 block_stmt_iterator bsi
, bsi_tgt
;
4410 new_bb
= create_empty_bb (bb
);
4412 /* Redirect the outgoing edges. */
4413 new_bb
->succs
= bb
->succs
;
4415 FOR_EACH_EDGE (e
, ei
, new_bb
->succs
)
4418 if (stmt
&& TREE_CODE ((tree
) stmt
) == LABEL_EXPR
)
4421 /* Move everything from BSI to the new basic block. */
4422 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
4424 act
= bsi_stmt (bsi
);
4425 if (TREE_CODE (act
) == LABEL_EXPR
)
4438 bsi_tgt
= bsi_start (new_bb
);
4439 while (!bsi_end_p (bsi
))
4441 act
= bsi_stmt (bsi
);
4443 bsi_insert_after (&bsi_tgt
, act
, BSI_NEW_STMT
);
4450 /* Moves basic block BB after block AFTER. */
4453 tree_move_block_after (basic_block bb
, basic_block after
)
4455 if (bb
->prev_bb
== after
)
4459 link_block (bb
, after
);
4465 /* Return true if basic_block can be duplicated. */
4468 tree_can_duplicate_bb_p (basic_block bb ATTRIBUTE_UNUSED
)
4473 /* Create a duplicate of the basic block BB. NOTE: This does not
4474 preserve SSA form. */
4477 tree_duplicate_bb (basic_block bb
)
4480 block_stmt_iterator bsi
, bsi_tgt
;
4482 ssa_op_iter op_iter
;
4484 new_bb
= create_empty_bb (EXIT_BLOCK_PTR
->prev_bb
);
4486 /* First copy the phi nodes. We do not copy phi node arguments here,
4487 since the edges are not ready yet. Keep the chain of phi nodes in
4488 the same order, so that we can add them later. */
4489 for (phi
= phi_nodes (bb
); phi
; phi
= PHI_CHAIN (phi
))
4491 mark_for_rewrite (PHI_RESULT (phi
));
4492 create_phi_node (PHI_RESULT (phi
), new_bb
);
4494 set_phi_nodes (new_bb
, phi_reverse (phi_nodes (new_bb
)));
4496 bsi_tgt
= bsi_start (new_bb
);
4497 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
4499 tree stmt
= bsi_stmt (bsi
);
4502 if (TREE_CODE (stmt
) == LABEL_EXPR
)
4505 /* Record the definitions. */
4506 get_stmt_operands (stmt
);
4508 FOR_EACH_SSA_TREE_OPERAND (val
, stmt
, op_iter
, SSA_OP_ALL_DEFS
)
4509 mark_for_rewrite (val
);
4511 copy
= unshare_expr (stmt
);
4513 /* Copy also the virtual operands. */
4514 get_stmt_ann (copy
);
4515 copy_virtual_operands (copy
, stmt
);
4517 bsi_insert_after (&bsi_tgt
, copy
, BSI_NEW_STMT
);
4523 /* Basic block BB_COPY was created by code duplication. Add phi node
4524 arguments for edges going out of BB_COPY. The blocks that were
4525 duplicated have rbi->duplicated set to one. */
4528 add_phi_args_after_copy_bb (basic_block bb_copy
)
4530 basic_block bb
, dest
;
4533 tree phi
, phi_copy
, phi_next
, def
;
4535 bb
= bb_copy
->rbi
->original
;
4537 FOR_EACH_EDGE (e_copy
, ei
, bb_copy
->succs
)
4539 if (!phi_nodes (e_copy
->dest
))
4542 if (e_copy
->dest
->rbi
->duplicated
)
4543 dest
= e_copy
->dest
->rbi
->original
;
4545 dest
= e_copy
->dest
;
4547 e
= find_edge (bb
, dest
);
4550 /* During loop unrolling the target of the latch edge is copied.
4551 In this case we are not looking for edge to dest, but to
4552 duplicated block whose original was dest. */
4553 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
4554 if (e
->dest
->rbi
->duplicated
4555 && e
->dest
->rbi
->original
== dest
)
4558 gcc_assert (e
!= NULL
);
4561 for (phi
= phi_nodes (e
->dest
), phi_copy
= phi_nodes (e_copy
->dest
);
4563 phi
= phi_next
, phi_copy
= PHI_CHAIN (phi_copy
))
4565 phi_next
= PHI_CHAIN (phi
);
4567 gcc_assert (PHI_RESULT (phi
) == PHI_RESULT (phi_copy
));
4568 def
= PHI_ARG_DEF_FROM_EDGE (phi
, e
);
4569 add_phi_arg (&phi_copy
, def
, e_copy
);
4574 /* Blocks in REGION_COPY array of length N_REGION were created by
4575 duplication of basic blocks. Add phi node arguments for edges
4576 going from these blocks. */
4579 add_phi_args_after_copy (basic_block
*region_copy
, unsigned n_region
)
4583 for (i
= 0; i
< n_region
; i
++)
4584 region_copy
[i
]->rbi
->duplicated
= 1;
4586 for (i
= 0; i
< n_region
; i
++)
4587 add_phi_args_after_copy_bb (region_copy
[i
]);
4589 for (i
= 0; i
< n_region
; i
++)
4590 region_copy
[i
]->rbi
->duplicated
= 0;
4593 /* Maps the old ssa name FROM_NAME to TO_NAME. */
4595 struct ssa_name_map_entry
4601 /* Hash function for ssa_name_map_entry. */
4604 ssa_name_map_entry_hash (const void *entry
)
4606 const struct ssa_name_map_entry
*en
= entry
;
4607 return SSA_NAME_VERSION (en
->from_name
);
4610 /* Equality function for ssa_name_map_entry. */
4613 ssa_name_map_entry_eq (const void *in_table
, const void *ssa_name
)
4615 const struct ssa_name_map_entry
*en
= in_table
;
4617 return en
->from_name
== ssa_name
;
4620 /* Allocate duplicates of ssa names in list DEFINITIONS and store the mapping
4624 allocate_ssa_names (bitmap definitions
, htab_t
*map
)
4627 struct ssa_name_map_entry
*entry
;
4633 *map
= htab_create (10, ssa_name_map_entry_hash
,
4634 ssa_name_map_entry_eq
, free
);
4635 EXECUTE_IF_SET_IN_BITMAP (definitions
, 0, ver
, bi
)
4637 name
= ssa_name (ver
);
4638 slot
= htab_find_slot_with_hash (*map
, name
, SSA_NAME_VERSION (name
),
4644 entry
= xmalloc (sizeof (struct ssa_name_map_entry
));
4645 entry
->from_name
= name
;
4648 entry
->to_name
= duplicate_ssa_name (name
, SSA_NAME_DEF_STMT (name
));
4652 /* Rewrite the definition DEF in statement STMT to new ssa name as specified
4653 by the mapping MAP. */
4656 rewrite_to_new_ssa_names_def (def_operand_p def
, tree stmt
, htab_t map
)
4658 tree name
= DEF_FROM_PTR (def
);
4659 struct ssa_name_map_entry
*entry
;
4661 gcc_assert (TREE_CODE (name
) == SSA_NAME
);
4663 entry
= htab_find_with_hash (map
, name
, SSA_NAME_VERSION (name
));
4667 SET_DEF (def
, entry
->to_name
);
4668 SSA_NAME_DEF_STMT (entry
->to_name
) = stmt
;
4671 /* Rewrite the USE to new ssa name as specified by the mapping MAP. */
4674 rewrite_to_new_ssa_names_use (use_operand_p use
, htab_t map
)
4676 tree name
= USE_FROM_PTR (use
);
4677 struct ssa_name_map_entry
*entry
;
4679 if (TREE_CODE (name
) != SSA_NAME
)
4682 entry
= htab_find_with_hash (map
, name
, SSA_NAME_VERSION (name
));
4686 SET_USE (use
, entry
->to_name
);
4689 /* Rewrite the ssa names in basic block BB to new ones as specified by the
4693 rewrite_to_new_ssa_names_bb (basic_block bb
, htab_t map
)
4699 block_stmt_iterator bsi
;
4703 v_may_def_optype v_may_defs
;
4704 v_must_def_optype v_must_defs
;
4707 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
4708 if (e
->flags
& EDGE_ABNORMAL
)
4711 for (phi
= phi_nodes (bb
); phi
; phi
= PHI_CHAIN (phi
))
4713 rewrite_to_new_ssa_names_def (PHI_RESULT_PTR (phi
), phi
, map
);
4715 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (PHI_RESULT (phi
)) = 1;
4718 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
4720 stmt
= bsi_stmt (bsi
);
4721 get_stmt_operands (stmt
);
4722 ann
= stmt_ann (stmt
);
4724 uses
= USE_OPS (ann
);
4725 for (i
= 0; i
< NUM_USES (uses
); i
++)
4726 rewrite_to_new_ssa_names_use (USE_OP_PTR (uses
, i
), map
);
4728 defs
= DEF_OPS (ann
);
4729 for (i
= 0; i
< NUM_DEFS (defs
); i
++)
4730 rewrite_to_new_ssa_names_def (DEF_OP_PTR (defs
, i
), stmt
, map
);
4732 vuses
= VUSE_OPS (ann
);
4733 for (i
= 0; i
< NUM_VUSES (vuses
); i
++)
4734 rewrite_to_new_ssa_names_use (VUSE_OP_PTR (vuses
, i
), map
);
4736 v_may_defs
= V_MAY_DEF_OPS (ann
);
4737 for (i
= 0; i
< NUM_V_MAY_DEFS (v_may_defs
); i
++)
4739 rewrite_to_new_ssa_names_use
4740 (V_MAY_DEF_OP_PTR (v_may_defs
, i
), map
);
4741 rewrite_to_new_ssa_names_def
4742 (V_MAY_DEF_RESULT_PTR (v_may_defs
, i
), stmt
, map
);
4745 v_must_defs
= V_MUST_DEF_OPS (ann
);
4746 for (i
= 0; i
< NUM_V_MUST_DEFS (v_must_defs
); i
++)
4748 rewrite_to_new_ssa_names_def
4749 (V_MUST_DEF_RESULT_PTR (v_must_defs
, i
), stmt
, map
);
4750 rewrite_to_new_ssa_names_use
4751 (V_MUST_DEF_KILL_PTR (v_must_defs
, i
), map
);
4755 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
4756 for (phi
= phi_nodes (e
->dest
); phi
; phi
= PHI_CHAIN (phi
))
4758 rewrite_to_new_ssa_names_use
4759 (PHI_ARG_DEF_PTR_FROM_EDGE (phi
, e
), map
);
4761 if (e
->flags
& EDGE_ABNORMAL
)
4763 tree op
= PHI_ARG_DEF_FROM_EDGE (phi
, e
);
4764 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op
) = 1;
4769 /* Rewrite the ssa names in N_REGION blocks REGION to the new ones as specified
4770 by the mapping MAP. */
4773 rewrite_to_new_ssa_names (basic_block
*region
, unsigned n_region
, htab_t map
)
4777 for (r
= 0; r
< n_region
; r
++)
4778 rewrite_to_new_ssa_names_bb (region
[r
], map
);
4781 /* Duplicates a REGION (set of N_REGION basic blocks) with just a single
4782 important exit edge EXIT. By important we mean that no SSA name defined
4783 inside region is live over the other exit edges of the region. All entry
4784 edges to the region must go to ENTRY->dest. The edge ENTRY is redirected
4785 to the duplicate of the region. SSA form, dominance and loop information
4786 is updated. The new basic blocks are stored to REGION_COPY in the same
4787 order as they had in REGION, provided that REGION_COPY is not NULL.
4788 The function returns false if it is unable to copy the region,
4792 tree_duplicate_sese_region (edge entry
, edge exit
,
4793 basic_block
*region
, unsigned n_region
,
4794 basic_block
*region_copy
)
4796 unsigned i
, n_doms
, ver
;
4797 bool free_region_copy
= false, copying_header
= false;
4798 struct loop
*loop
= entry
->dest
->loop_father
;
4803 htab_t ssa_name_map
= NULL
;
4807 if (!can_copy_bbs_p (region
, n_region
))
4810 /* Some sanity checking. Note that we do not check for all possible
4811 missuses of the functions. I.e. if you ask to copy something weird,
4812 it will work, but the state of structures probably will not be
4815 for (i
= 0; i
< n_region
; i
++)
4817 /* We do not handle subloops, i.e. all the blocks must belong to the
4819 if (region
[i
]->loop_father
!= loop
)
4822 if (region
[i
] != entry
->dest
4823 && region
[i
] == loop
->header
)
4829 /* In case the function is used for loop header copying (which is the primary
4830 use), ensure that EXIT and its copy will be new latch and entry edges. */
4831 if (loop
->header
== entry
->dest
)
4833 copying_header
= true;
4834 loop
->copy
= loop
->outer
;
4836 if (!dominated_by_p (CDI_DOMINATORS
, loop
->latch
, exit
->src
))
4839 for (i
= 0; i
< n_region
; i
++)
4840 if (region
[i
] != exit
->src
4841 && dominated_by_p (CDI_DOMINATORS
, region
[i
], exit
->src
))
4847 region_copy
= xmalloc (sizeof (basic_block
) * n_region
);
4848 free_region_copy
= true;
4851 gcc_assert (!any_marked_for_rewrite_p ());
4853 /* Record blocks outside the region that are duplicated by something
4855 doms
= xmalloc (sizeof (basic_block
) * n_basic_blocks
);
4856 n_doms
= get_dominated_by_region (CDI_DOMINATORS
, region
, n_region
, doms
);
4858 copy_bbs (region
, n_region
, region_copy
, &exit
, 1, &exit_copy
, loop
);
4859 definitions
= marked_ssa_names ();
4863 loop
->header
= exit
->dest
;
4864 loop
->latch
= exit
->src
;
4867 /* Redirect the entry and add the phi node arguments. */
4868 redirected
= redirect_edge_and_branch (entry
, entry
->dest
->rbi
->copy
);
4869 gcc_assert (redirected
!= NULL
);
4870 flush_pending_stmts (entry
);
4872 /* Concerning updating of dominators: We must recount dominators
4873 for entry block and its copy. Anything that is outside of the region, but
4874 was dominated by something inside needs recounting as well. */
4875 set_immediate_dominator (CDI_DOMINATORS
, entry
->dest
, entry
->src
);
4876 doms
[n_doms
++] = entry
->dest
->rbi
->original
;
4877 iterate_fix_dominators (CDI_DOMINATORS
, doms
, n_doms
);
4880 /* Add the other phi node arguments. */
4881 add_phi_args_after_copy (region_copy
, n_region
);
4883 /* Add phi nodes for definitions at exit. TODO -- once we have immediate
4884 uses, it should be possible to emit phi nodes just for definitions that
4885 are used outside region. */
4886 EXECUTE_IF_SET_IN_BITMAP (definitions
, 0, ver
, bi
)
4888 tree name
= ssa_name (ver
);
4890 phi
= create_phi_node (name
, exit
->dest
);
4891 add_phi_arg (&phi
, name
, exit
);
4892 add_phi_arg (&phi
, name
, exit_copy
);
4894 SSA_NAME_DEF_STMT (name
) = phi
;
4897 /* And create new definitions inside region and its copy. TODO -- once we
4898 have immediate uses, it might be better to leave definitions in region
4899 unchanged, create new ssa names for phi nodes on exit, and rewrite
4900 the uses, to avoid changing the copied region. */
4901 allocate_ssa_names (definitions
, &ssa_name_map
);
4902 rewrite_to_new_ssa_names (region
, n_region
, ssa_name_map
);
4903 allocate_ssa_names (definitions
, &ssa_name_map
);
4904 rewrite_to_new_ssa_names (region_copy
, n_region
, ssa_name_map
);
4905 htab_delete (ssa_name_map
);
4907 if (free_region_copy
)
4910 unmark_all_for_rewrite ();
4911 BITMAP_XFREE (definitions
);
4916 /* Dump FUNCTION_DECL FN to file FILE using FLAGS (see TDF_* in tree.h) */
4919 dump_function_to_file (tree fn
, FILE *file
, int flags
)
4921 tree arg
, vars
, var
;
4922 bool ignore_topmost_bind
= false, any_var
= false;
4926 fprintf (file
, "%s (", lang_hooks
.decl_printable_name (fn
, 2));
4928 arg
= DECL_ARGUMENTS (fn
);
4931 print_generic_expr (file
, arg
, dump_flags
);
4932 if (TREE_CHAIN (arg
))
4933 fprintf (file
, ", ");
4934 arg
= TREE_CHAIN (arg
);
4936 fprintf (file
, ")\n");
4938 if (flags
& TDF_RAW
)
4940 dump_node (fn
, TDF_SLIM
| flags
, file
);
4944 /* When GIMPLE is lowered, the variables are no longer available in
4945 BIND_EXPRs, so display them separately. */
4946 if (cfun
&& cfun
->unexpanded_var_list
)
4948 ignore_topmost_bind
= true;
4950 fprintf (file
, "{\n");
4951 for (vars
= cfun
->unexpanded_var_list
; vars
; vars
= TREE_CHAIN (vars
))
4953 var
= TREE_VALUE (vars
);
4955 print_generic_decl (file
, var
, flags
);
4956 fprintf (file
, "\n");
4962 if (basic_block_info
)
4964 /* Make a CFG based dump. */
4965 check_bb_profile (ENTRY_BLOCK_PTR
, file
);
4966 if (!ignore_topmost_bind
)
4967 fprintf (file
, "{\n");
4969 if (any_var
&& n_basic_blocks
)
4970 fprintf (file
, "\n");
4973 dump_generic_bb (file
, bb
, 2, flags
);
4975 fprintf (file
, "}\n");
4976 check_bb_profile (EXIT_BLOCK_PTR
, file
);
4982 /* Make a tree based dump. */
4983 chain
= DECL_SAVED_TREE (fn
);
4985 if (TREE_CODE (chain
) == BIND_EXPR
)
4987 if (ignore_topmost_bind
)
4989 chain
= BIND_EXPR_BODY (chain
);
4997 if (!ignore_topmost_bind
)
4998 fprintf (file
, "{\n");
5003 fprintf (file
, "\n");
5005 print_generic_stmt_indented (file
, chain
, flags
, indent
);
5006 if (ignore_topmost_bind
)
5007 fprintf (file
, "}\n");
5010 fprintf (file
, "\n\n");
5014 /* Pretty print of the loops intermediate representation. */
5015 static void print_loop (FILE *, struct loop
*, int);
5016 static void print_pred_bbs (FILE *, basic_block bb
);
5017 static void print_succ_bbs (FILE *, basic_block bb
);
5020 /* Print the predecessors indexes of edge E on FILE. */
5023 print_pred_bbs (FILE *file
, basic_block bb
)
5028 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
5029 fprintf (file
, "bb_%d", e
->src
->index
);
5033 /* Print the successors indexes of edge E on FILE. */
5036 print_succ_bbs (FILE *file
, basic_block bb
)
5041 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
5042 fprintf (file
, "bb_%d", e
->src
->index
);
5046 /* Pretty print LOOP on FILE, indented INDENT spaces. */
5049 print_loop (FILE *file
, struct loop
*loop
, int indent
)
5057 s_indent
= (char *) alloca ((size_t) indent
+ 1);
5058 memset ((void *) s_indent
, ' ', (size_t) indent
);
5059 s_indent
[indent
] = '\0';
5061 /* Print the loop's header. */
5062 fprintf (file
, "%sloop_%d\n", s_indent
, loop
->num
);
5064 /* Print the loop's body. */
5065 fprintf (file
, "%s{\n", s_indent
);
5067 if (bb
->loop_father
== loop
)
5069 /* Print the basic_block's header. */
5070 fprintf (file
, "%s bb_%d (preds = {", s_indent
, bb
->index
);
5071 print_pred_bbs (file
, bb
);
5072 fprintf (file
, "}, succs = {");
5073 print_succ_bbs (file
, bb
);
5074 fprintf (file
, "})\n");
5076 /* Print the basic_block's body. */
5077 fprintf (file
, "%s {\n", s_indent
);
5078 tree_dump_bb (bb
, file
, indent
+ 4);
5079 fprintf (file
, "%s }\n", s_indent
);
5082 print_loop (file
, loop
->inner
, indent
+ 2);
5083 fprintf (file
, "%s}\n", s_indent
);
5084 print_loop (file
, loop
->next
, indent
);
5088 /* Follow a CFG edge from the entry point of the program, and on entry
5089 of a loop, pretty print the loop structure on FILE. */
5092 print_loop_ir (FILE *file
)
5096 bb
= BASIC_BLOCK (0);
5097 if (bb
&& bb
->loop_father
)
5098 print_loop (file
, bb
->loop_father
, 0);
5102 /* Debugging loops structure at tree level. */
5105 debug_loop_ir (void)
5107 print_loop_ir (stderr
);
5111 /* Return true if BB ends with a call, possibly followed by some
5112 instructions that must stay with the call. Return false,
5116 tree_block_ends_with_call_p (basic_block bb
)
5118 block_stmt_iterator bsi
= bsi_last (bb
);
5119 return get_call_expr_in (bsi_stmt (bsi
)) != NULL
;
5123 /* Return true if BB ends with a conditional branch. Return false,
5127 tree_block_ends_with_condjump_p (basic_block bb
)
5129 tree stmt
= tsi_stmt (bsi_last (bb
).tsi
);
5130 return (TREE_CODE (stmt
) == COND_EXPR
);
5134 /* Return true if we need to add fake edge to exit at statement T.
5135 Helper function for tree_flow_call_edges_add. */
5138 need_fake_edge_p (tree t
)
5142 /* NORETURN and LONGJMP calls already have an edge to exit.
5143 CONST, PURE and ALWAYS_RETURN calls do not need one.
5144 We don't currently check for CONST and PURE here, although
5145 it would be a good idea, because those attributes are
5146 figured out from the RTL in mark_constant_function, and
5147 the counter incrementation code from -fprofile-arcs
5148 leads to different results from -fbranch-probabilities. */
5149 call
= get_call_expr_in (t
);
5151 && !(call_expr_flags (call
) & (ECF_NORETURN
| ECF_ALWAYS_RETURN
)))
5154 if (TREE_CODE (t
) == ASM_EXPR
5155 && (ASM_VOLATILE_P (t
) || ASM_INPUT_P (t
)))
5162 /* Add fake edges to the function exit for any non constant and non
5163 noreturn calls, volatile inline assembly in the bitmap of blocks
5164 specified by BLOCKS or to the whole CFG if BLOCKS is zero. Return
5165 the number of blocks that were split.
5167 The goal is to expose cases in which entering a basic block does
5168 not imply that all subsequent instructions must be executed. */
5171 tree_flow_call_edges_add (sbitmap blocks
)
5174 int blocks_split
= 0;
5175 int last_bb
= last_basic_block
;
5176 bool check_last_block
= false;
5178 if (n_basic_blocks
== 0)
5182 check_last_block
= true;
5184 check_last_block
= TEST_BIT (blocks
, EXIT_BLOCK_PTR
->prev_bb
->index
);
5186 /* In the last basic block, before epilogue generation, there will be
5187 a fallthru edge to EXIT. Special care is required if the last insn
5188 of the last basic block is a call because make_edge folds duplicate
5189 edges, which would result in the fallthru edge also being marked
5190 fake, which would result in the fallthru edge being removed by
5191 remove_fake_edges, which would result in an invalid CFG.
5193 Moreover, we can't elide the outgoing fake edge, since the block
5194 profiler needs to take this into account in order to solve the minimal
5195 spanning tree in the case that the call doesn't return.
5197 Handle this by adding a dummy instruction in a new last basic block. */
5198 if (check_last_block
)
5200 basic_block bb
= EXIT_BLOCK_PTR
->prev_bb
;
5201 block_stmt_iterator bsi
= bsi_last (bb
);
5203 if (!bsi_end_p (bsi
))
5206 if (need_fake_edge_p (t
))
5210 e
= find_edge (bb
, EXIT_BLOCK_PTR
);
5213 bsi_insert_on_edge (e
, build_empty_stmt ());
5214 bsi_commit_edge_inserts ();
5219 /* Now add fake edges to the function exit for any non constant
5220 calls since there is no way that we can determine if they will
5222 for (i
= 0; i
< last_bb
; i
++)
5224 basic_block bb
= BASIC_BLOCK (i
);
5225 block_stmt_iterator bsi
;
5226 tree stmt
, last_stmt
;
5231 if (blocks
&& !TEST_BIT (blocks
, i
))
5234 bsi
= bsi_last (bb
);
5235 if (!bsi_end_p (bsi
))
5237 last_stmt
= bsi_stmt (bsi
);
5240 stmt
= bsi_stmt (bsi
);
5241 if (need_fake_edge_p (stmt
))
5244 /* The handling above of the final block before the
5245 epilogue should be enough to verify that there is
5246 no edge to the exit block in CFG already.
5247 Calling make_edge in such case would cause us to
5248 mark that edge as fake and remove it later. */
5249 #ifdef ENABLE_CHECKING
5250 if (stmt
== last_stmt
)
5252 e
= find_edge (bb
, EXIT_BLOCK_PTR
);
5253 gcc_assert (e
== NULL
);
5257 /* Note that the following may create a new basic block
5258 and renumber the existing basic blocks. */
5259 if (stmt
!= last_stmt
)
5261 e
= split_block (bb
, stmt
);
5265 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
5269 while (!bsi_end_p (bsi
));
5274 verify_flow_info ();
5276 return blocks_split
;
5280 tree_purge_dead_eh_edges (basic_block bb
)
5282 bool changed
= false;
5285 tree stmt
= last_stmt (bb
);
5287 if (stmt
&& tree_can_throw_internal (stmt
))
5290 for (ei
= ei_start (bb
->succs
); (e
= ei_safe_edge (ei
)); )
5292 if (e
->flags
& EDGE_EH
)
5301 /* Removal of dead EH edges might change dominators of not
5302 just immediate successors. E.g. when bb1 is changed so that
5303 it no longer can throw and bb1->bb3 and bb1->bb4 are dead
5304 eh edges purged by this function in:
5316 idom(bb5) must be recomputed. For now just free the dominance
5319 free_dominance_info (CDI_DOMINATORS
);
5325 tree_purge_all_dead_eh_edges (bitmap blocks
)
5327 bool changed
= false;
5331 EXECUTE_IF_SET_IN_BITMAP (blocks
, 0, i
, bi
)
5333 changed
|= tree_purge_dead_eh_edges (BASIC_BLOCK (i
));
5339 /* This function is called whenever a new edge is created or
5343 tree_execute_on_growing_pred (edge e
)
5345 basic_block bb
= e
->dest
;
5348 reserve_phi_args_for_new_edge (bb
);
5351 /* This function is called immediately before edge E is removed from
5352 the edge vector E->dest->preds. */
5355 tree_execute_on_shrinking_pred (edge e
)
5357 if (phi_nodes (e
->dest
))
5358 remove_phi_args (e
);
5361 struct cfg_hooks tree_cfg_hooks
= {
5363 tree_verify_flow_info
,
5364 tree_dump_bb
, /* dump_bb */
5365 create_bb
, /* create_basic_block */
5366 tree_redirect_edge_and_branch
,/* redirect_edge_and_branch */
5367 tree_redirect_edge_and_branch_force
,/* redirect_edge_and_branch_force */
5368 remove_bb
, /* delete_basic_block */
5369 tree_split_block
, /* split_block */
5370 tree_move_block_after
, /* move_block_after */
5371 tree_can_merge_blocks_p
, /* can_merge_blocks_p */
5372 tree_merge_blocks
, /* merge_blocks */
5373 tree_predict_edge
, /* predict_edge */
5374 tree_predicted_by_p
, /* predicted_by_p */
5375 tree_can_duplicate_bb_p
, /* can_duplicate_block_p */
5376 tree_duplicate_bb
, /* duplicate_block */
5377 tree_split_edge
, /* split_edge */
5378 tree_make_forwarder_block
, /* make_forward_block */
5379 NULL
, /* tidy_fallthru_edge */
5380 tree_block_ends_with_call_p
, /* block_ends_with_call_p */
5381 tree_block_ends_with_condjump_p
, /* block_ends_with_condjump_p */
5382 tree_flow_call_edges_add
, /* flow_call_edges_add */
5383 tree_execute_on_growing_pred
, /* execute_on_growing_pred */
5384 tree_execute_on_shrinking_pred
, /* execute_on_shrinking_pred */
5388 /* Split all critical edges. */
5391 split_critical_edges (void)
5397 /* split_edge can redirect edges out of SWITCH_EXPRs, which can get
5398 expensive. So we want to enable recording of edge to CASE_LABEL_EXPR
5399 mappings around the calls to split_edge. */
5400 start_recording_case_labels ();
5403 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
5404 if (EDGE_CRITICAL_P (e
) && !(e
->flags
& EDGE_ABNORMAL
))
5409 end_recording_case_labels ();
5412 struct tree_opt_pass pass_split_crit_edges
=
5414 "crited", /* name */
5416 split_critical_edges
, /* execute */
5419 0, /* static_pass_number */
5420 TV_TREE_SPLIT_EDGES
, /* tv_id */
5421 PROP_cfg
, /* properties required */
5422 PROP_no_crit_edges
, /* properties_provided */
5423 0, /* properties_destroyed */
5424 0, /* todo_flags_start */
5425 TODO_dump_func
, /* todo_flags_finish */
5430 /* Return EXP if it is a valid GIMPLE rvalue, else gimplify it into
5431 a temporary, make sure and register it to be renamed if necessary,
5432 and finally return the temporary. Put the statements to compute
5433 EXP before the current statement in BSI. */
5436 gimplify_val (block_stmt_iterator
*bsi
, tree type
, tree exp
)
5438 tree t
, new_stmt
, orig_stmt
;
5440 if (is_gimple_val (exp
))
5443 t
= make_rename_temp (type
, NULL
);
5444 new_stmt
= build (MODIFY_EXPR
, type
, t
, exp
);
5446 orig_stmt
= bsi_stmt (*bsi
);
5447 SET_EXPR_LOCUS (new_stmt
, EXPR_LOCUS (orig_stmt
));
5448 TREE_BLOCK (new_stmt
) = TREE_BLOCK (orig_stmt
);
5450 bsi_insert_before (bsi
, new_stmt
, BSI_SAME_STMT
);
5455 /* Build a ternary operation and gimplify it. Emit code before BSI.
5456 Return the gimple_val holding the result. */
5459 gimplify_build3 (block_stmt_iterator
*bsi
, enum tree_code code
,
5460 tree type
, tree a
, tree b
, tree c
)
5464 ret
= fold (build3 (code
, type
, a
, b
, c
));
5467 return gimplify_val (bsi
, type
, ret
);
5470 /* Build a binary operation and gimplify it. Emit code before BSI.
5471 Return the gimple_val holding the result. */
5474 gimplify_build2 (block_stmt_iterator
*bsi
, enum tree_code code
,
5475 tree type
, tree a
, tree b
)
5479 ret
= fold (build2 (code
, type
, a
, b
));
5482 return gimplify_val (bsi
, type
, ret
);
5485 /* Build a unary operation and gimplify it. Emit code before BSI.
5486 Return the gimple_val holding the result. */
5489 gimplify_build1 (block_stmt_iterator
*bsi
, enum tree_code code
, tree type
,
5494 ret
= fold (build1 (code
, type
, a
));
5497 return gimplify_val (bsi
, type
, ret
);
5502 /* Emit return warnings. */
5505 execute_warn_function_return (void)
5507 #ifdef USE_MAPPED_LOCATION
5508 source_location location
;
5516 if (warn_missing_noreturn
5517 && !TREE_THIS_VOLATILE (cfun
->decl
)
5518 && EDGE_COUNT (EXIT_BLOCK_PTR
->preds
) == 0
5519 && !lang_hooks
.function
.missing_noreturn_ok_p (cfun
->decl
))
5520 warning ("%Jfunction might be possible candidate for "
5521 "attribute %<noreturn%>",
5524 /* If we have a path to EXIT, then we do return. */
5525 if (TREE_THIS_VOLATILE (cfun
->decl
)
5526 && EDGE_COUNT (EXIT_BLOCK_PTR
->preds
) > 0)
5528 #ifdef USE_MAPPED_LOCATION
5529 location
= UNKNOWN_LOCATION
;
5533 FOR_EACH_EDGE (e
, ei
, EXIT_BLOCK_PTR
->preds
)
5535 last
= last_stmt (e
->src
);
5536 if (TREE_CODE (last
) == RETURN_EXPR
5537 #ifdef USE_MAPPED_LOCATION
5538 && (location
= EXPR_LOCATION (last
)) != UNKNOWN_LOCATION
)
5540 && (locus
= EXPR_LOCUS (last
)) != NULL
)
5544 #ifdef USE_MAPPED_LOCATION
5545 if (location
== UNKNOWN_LOCATION
)
5546 location
= cfun
->function_end_locus
;
5547 warning ("%H%<noreturn%> function does return", &location
);
5550 locus
= &cfun
->function_end_locus
;
5551 warning ("%H%<noreturn%> function does return", locus
);
5555 /* If we see "return;" in some basic block, then we do reach the end
5556 without returning a value. */
5557 else if (warn_return_type
5558 && EDGE_COUNT (EXIT_BLOCK_PTR
->preds
) > 0
5559 && !VOID_TYPE_P (TREE_TYPE (TREE_TYPE (cfun
->decl
))))
5561 FOR_EACH_EDGE (e
, ei
, EXIT_BLOCK_PTR
->preds
)
5563 tree last
= last_stmt (e
->src
);
5564 if (TREE_CODE (last
) == RETURN_EXPR
5565 && TREE_OPERAND (last
, 0) == NULL
)
5567 #ifdef USE_MAPPED_LOCATION
5568 location
= EXPR_LOCATION (last
);
5569 if (location
== UNKNOWN_LOCATION
)
5570 location
= cfun
->function_end_locus
;
5571 warning ("%Hcontrol reaches end of non-void function", &location
);
5573 locus
= EXPR_LOCUS (last
);
5575 locus
= &cfun
->function_end_locus
;
5576 warning ("%Hcontrol reaches end of non-void function", locus
);
5585 /* Given a basic block B which ends with a conditional and has
5586 precisely two successors, determine which of the edges is taken if
5587 the conditional is true and which is taken if the conditional is
5588 false. Set TRUE_EDGE and FALSE_EDGE appropriately. */
5591 extract_true_false_edges_from_block (basic_block b
,
5595 edge e
= EDGE_SUCC (b
, 0);
5597 if (e
->flags
& EDGE_TRUE_VALUE
)
5600 *false_edge
= EDGE_SUCC (b
, 1);
5605 *true_edge
= EDGE_SUCC (b
, 1);
5609 struct tree_opt_pass pass_warn_function_return
=
5613 execute_warn_function_return
, /* execute */
5616 0, /* static_pass_number */
5618 PROP_cfg
, /* properties_required */
5619 0, /* properties_provided */
5620 0, /* properties_destroyed */
5621 0, /* todo_flags_start */
5622 0, /* todo_flags_finish */
5626 #include "gt-tree-cfg.h"