1 /* Control flow functions for trees.
2 Copyright (C) 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
3 Contributed by Diego Novillo <dnovillo@redhat.com>
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 GCC is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to
19 the Free Software Foundation, 59 Temple Place - Suite 330,
20 Boston, MA 02111-1307, USA. */
24 #include "coretypes.h"
29 #include "hard-reg-set.h"
30 #include "basic-block.h"
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);
117 static bool remove_fallthru_edge (VEC(edge
) *);
119 /* Various helpers. */
120 static inline bool stmt_starts_bb_p (tree
, tree
);
121 static int tree_verify_flow_info (void);
122 static void tree_make_forwarder_block (edge
);
123 static bool tree_forwarder_block_p (basic_block
, bool);
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
);
136 static bool cleanup_forwarder_blocks (void);
139 /*---------------------------------------------------------------------------
141 ---------------------------------------------------------------------------*/
143 /* Entry point to the CFG builder for trees. TP points to the list of
144 statements to be added to the flowgraph. */
147 build_tree_cfg (tree
*tp
)
149 /* Register specific tree functions. */
150 tree_register_cfg_hooks ();
152 /* Initialize rbi_pool. */
155 /* Initialize the basic block array. */
157 profile_status
= PROFILE_ABSENT
;
159 last_basic_block
= 0;
160 VARRAY_BB_INIT (basic_block_info
, initial_cfg_capacity
, "basic_block_info");
161 memset ((void *) &cfg_stats
, 0, sizeof (cfg_stats
));
163 /* Build a mapping of labels to their associated blocks. */
164 VARRAY_BB_INIT (label_to_block_map
, initial_cfg_capacity
,
165 "label to block map");
167 ENTRY_BLOCK_PTR
->next_bb
= EXIT_BLOCK_PTR
;
168 EXIT_BLOCK_PTR
->prev_bb
= ENTRY_BLOCK_PTR
;
170 found_computed_goto
= 0;
173 /* Computed gotos are hell to deal with, especially if there are
174 lots of them with a large number of destinations. So we factor
175 them to a common computed goto location before we build the
176 edge list. After we convert back to normal form, we will un-factor
177 the computed gotos since factoring introduces an unwanted jump. */
178 if (found_computed_goto
)
179 factor_computed_gotos ();
181 /* Make sure there is always at least one block, even if it's empty. */
182 if (n_basic_blocks
== 0)
183 create_empty_bb (ENTRY_BLOCK_PTR
);
185 create_block_annotation (ENTRY_BLOCK_PTR
);
186 create_block_annotation (EXIT_BLOCK_PTR
);
188 /* Adjust the size of the array. */
189 VARRAY_GROW (basic_block_info
, n_basic_blocks
);
191 /* To speed up statement iterator walks, we first purge dead labels. */
192 cleanup_dead_labels ();
194 /* Group case nodes to reduce the number of edges.
195 We do this after cleaning up dead labels because otherwise we miss
196 a lot of obvious case merging opportunities. */
197 group_case_labels ();
199 /* Create the edges of the flowgraph. */
202 /* Debugging dumps. */
204 /* Write the flowgraph to a VCG file. */
206 int local_dump_flags
;
207 FILE *dump_file
= dump_begin (TDI_vcg
, &local_dump_flags
);
210 tree_cfg2vcg (dump_file
);
211 dump_end (TDI_vcg
, dump_file
);
215 /* Dump a textual representation of the flowgraph. */
217 dump_tree_cfg (dump_file
, dump_flags
);
221 execute_build_cfg (void)
223 build_tree_cfg (&DECL_SAVED_TREE (current_function_decl
));
226 struct tree_opt_pass pass_build_cfg
=
230 execute_build_cfg
, /* execute */
233 0, /* static_pass_number */
234 TV_TREE_CFG
, /* tv_id */
235 PROP_gimple_leh
, /* properties_required */
236 PROP_cfg
, /* properties_provided */
237 0, /* properties_destroyed */
238 0, /* todo_flags_start */
239 TODO_verify_stmts
, /* todo_flags_finish */
243 /* Search the CFG for any computed gotos. If found, factor them to a
244 common computed goto site. Also record the location of that site so
245 that we can un-factor the gotos after we have converted back to
249 factor_computed_gotos (void)
252 tree factored_label_decl
= NULL
;
254 tree factored_computed_goto_label
= NULL
;
255 tree factored_computed_goto
= NULL
;
257 /* We know there are one or more computed gotos in this function.
258 Examine the last statement in each basic block to see if the block
259 ends with a computed goto. */
263 block_stmt_iterator bsi
= bsi_last (bb
);
268 last
= bsi_stmt (bsi
);
270 /* Ignore the computed goto we create when we factor the original
272 if (last
== factored_computed_goto
)
275 /* If the last statement is a computed goto, factor it. */
276 if (computed_goto_p (last
))
280 /* The first time we find a computed goto we need to create
281 the factored goto block and the variable each original
282 computed goto will use for their goto destination. */
283 if (! factored_computed_goto
)
285 basic_block new_bb
= create_empty_bb (bb
);
286 block_stmt_iterator new_bsi
= bsi_start (new_bb
);
288 /* Create the destination of the factored goto. Each original
289 computed goto will put its desired destination into this
290 variable and jump to the label we create immediately
292 var
= create_tmp_var (ptr_type_node
, "gotovar");
294 /* Build a label for the new block which will contain the
295 factored computed goto. */
296 factored_label_decl
= create_artificial_label ();
297 factored_computed_goto_label
298 = build1 (LABEL_EXPR
, void_type_node
, factored_label_decl
);
299 bsi_insert_after (&new_bsi
, factored_computed_goto_label
,
302 /* Build our new computed goto. */
303 factored_computed_goto
= build1 (GOTO_EXPR
, void_type_node
, var
);
304 bsi_insert_after (&new_bsi
, factored_computed_goto
,
308 /* Copy the original computed goto's destination into VAR. */
309 assignment
= build (MODIFY_EXPR
, ptr_type_node
,
310 var
, GOTO_DESTINATION (last
));
311 bsi_insert_before (&bsi
, assignment
, BSI_SAME_STMT
);
313 /* And re-vector the computed goto to the new destination. */
314 GOTO_DESTINATION (last
) = factored_label_decl
;
320 /* Create annotations for a single basic block. */
323 create_block_annotation (basic_block bb
)
325 /* Verify that the tree_annotations field is clear. */
326 gcc_assert (!bb
->tree_annotations
);
327 bb
->tree_annotations
= ggc_alloc_cleared (sizeof (struct bb_ann_d
));
331 /* Free the annotations for all the basic blocks. */
333 static void free_blocks_annotations (void)
335 clear_blocks_annotations ();
339 /* Clear the annotations for all the basic blocks. */
342 clear_blocks_annotations (void)
346 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
, NULL
, next_bb
)
347 bb
->tree_annotations
= NULL
;
351 /* Build a flowgraph for the statement_list STMT_LIST. */
354 make_blocks (tree stmt_list
)
356 tree_stmt_iterator i
= tsi_start (stmt_list
);
358 bool start_new_block
= true;
359 bool first_stmt_of_list
= true;
360 basic_block bb
= ENTRY_BLOCK_PTR
;
362 while (!tsi_end_p (i
))
369 /* If the statement starts a new basic block or if we have determined
370 in a previous pass that we need to create a new block for STMT, do
372 if (start_new_block
|| stmt_starts_bb_p (stmt
, prev_stmt
))
374 if (!first_stmt_of_list
)
375 stmt_list
= tsi_split_statement_list_before (&i
);
376 bb
= create_basic_block (stmt_list
, NULL
, bb
);
377 start_new_block
= false;
380 /* Now add STMT to BB and create the subgraphs for special statement
382 set_bb_for_stmt (stmt
, bb
);
384 if (computed_goto_p (stmt
))
385 found_computed_goto
= true;
387 /* If STMT is a basic block terminator, set START_NEW_BLOCK for the
389 if (stmt_ends_bb_p (stmt
))
390 start_new_block
= true;
393 first_stmt_of_list
= false;
398 /* Create and return a new empty basic block after bb AFTER. */
401 create_bb (void *h
, void *e
, basic_block after
)
407 /* Create and initialize a new basic block. Since alloc_block uses
408 ggc_alloc_cleared to allocate a basic block, we do not have to
409 clear the newly allocated basic block here. */
412 bb
->index
= last_basic_block
;
414 bb
->stmt_list
= h
? h
: alloc_stmt_list ();
416 /* Add the new block to the linked list of blocks. */
417 link_block (bb
, after
);
419 /* Grow the basic block array if needed. */
420 if ((size_t) last_basic_block
== VARRAY_SIZE (basic_block_info
))
422 size_t new_size
= last_basic_block
+ (last_basic_block
+ 3) / 4;
423 VARRAY_GROW (basic_block_info
, new_size
);
426 /* Add the newly created block to the array. */
427 BASIC_BLOCK (last_basic_block
) = bb
;
429 create_block_annotation (bb
);
434 initialize_bb_rbi (bb
);
439 /*---------------------------------------------------------------------------
441 ---------------------------------------------------------------------------*/
443 /* Fold COND_EXPR_COND of each COND_EXPR. */
446 fold_cond_expr_cond (void)
452 tree stmt
= last_stmt (bb
);
455 && TREE_CODE (stmt
) == COND_EXPR
)
457 tree cond
= fold (COND_EXPR_COND (stmt
));
458 if (integer_zerop (cond
))
459 COND_EXPR_COND (stmt
) = integer_zero_node
;
460 else if (integer_onep (cond
))
461 COND_EXPR_COND (stmt
) = integer_one_node
;
466 /* Join all the blocks in the flowgraph. */
473 /* Create an edge from entry to the first block with executable
475 make_edge (ENTRY_BLOCK_PTR
, BASIC_BLOCK (0), EDGE_FALLTHRU
);
477 /* Traverse the basic block array placing edges. */
480 tree first
= first_stmt (bb
);
481 tree last
= last_stmt (bb
);
485 /* Edges for statements that always alter flow control. */
486 if (is_ctrl_stmt (last
))
487 make_ctrl_stmt_edges (bb
);
489 /* Edges for statements that sometimes alter flow control. */
490 if (is_ctrl_altering_stmt (last
))
491 make_exit_edges (bb
);
494 /* Finally, if no edges were created above, this is a regular
495 basic block that only needs a fallthru edge. */
496 if (EDGE_COUNT (bb
->succs
) == 0)
497 make_edge (bb
, bb
->next_bb
, EDGE_FALLTHRU
);
500 /* We do not care about fake edges, so remove any that the CFG
501 builder inserted for completeness. */
502 remove_fake_exit_edges ();
504 /* Fold COND_EXPR_COND of each COND_EXPR. */
505 fold_cond_expr_cond ();
507 /* Clean up the graph and warn for unreachable code. */
512 /* Create edges for control statement at basic block BB. */
515 make_ctrl_stmt_edges (basic_block bb
)
517 tree last
= last_stmt (bb
);
520 switch (TREE_CODE (last
))
523 make_goto_expr_edges (bb
);
527 make_edge (bb
, EXIT_BLOCK_PTR
, 0);
531 make_cond_expr_edges (bb
);
535 make_switch_expr_edges (bb
);
539 make_eh_edges (last
);
540 /* Yet another NORETURN hack. */
541 if (EDGE_COUNT (bb
->succs
) == 0)
542 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
551 /* Create exit edges for statements in block BB that alter the flow of
552 control. Statements that alter the control flow are 'goto', 'return'
553 and calls to non-returning functions. */
556 make_exit_edges (basic_block bb
)
558 tree last
= last_stmt (bb
), op
;
561 switch (TREE_CODE (last
))
564 /* If this function receives a nonlocal goto, then we need to
565 make edges from this call site to all the nonlocal goto
567 if (TREE_SIDE_EFFECTS (last
)
568 && current_function_has_nonlocal_label
)
569 make_goto_expr_edges (bb
);
571 /* If this statement has reachable exception handlers, then
572 create abnormal edges to them. */
573 make_eh_edges (last
);
575 /* Some calls are known not to return. For such calls we create
578 We really need to revamp how we build edges so that it's not
579 such a bloody pain to avoid creating edges for this case since
580 all we do is remove these edges when we're done building the
582 if (call_expr_flags (last
) & ECF_NORETURN
)
584 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
588 /* Don't forget the fall-thru edge. */
589 make_edge (bb
, bb
->next_bb
, EDGE_FALLTHRU
);
593 /* A MODIFY_EXPR may have a CALL_EXPR on its RHS and the CALL_EXPR
594 may have an abnormal edge. Search the RHS for this case and
595 create any required edges. */
596 op
= get_call_expr_in (last
);
597 if (op
&& TREE_SIDE_EFFECTS (op
)
598 && current_function_has_nonlocal_label
)
599 make_goto_expr_edges (bb
);
601 make_eh_edges (last
);
602 make_edge (bb
, bb
->next_bb
, EDGE_FALLTHRU
);
611 /* Create the edges for a COND_EXPR starting at block BB.
612 At this point, both clauses must contain only simple gotos. */
615 make_cond_expr_edges (basic_block bb
)
617 tree entry
= last_stmt (bb
);
618 basic_block then_bb
, else_bb
;
619 tree then_label
, else_label
;
622 gcc_assert (TREE_CODE (entry
) == COND_EXPR
);
624 /* Entry basic blocks for each component. */
625 then_label
= GOTO_DESTINATION (COND_EXPR_THEN (entry
));
626 else_label
= GOTO_DESTINATION (COND_EXPR_ELSE (entry
));
627 then_bb
= label_to_block (then_label
);
628 else_bb
= label_to_block (else_label
);
630 make_edge (bb
, then_bb
, EDGE_TRUE_VALUE
);
631 make_edge (bb
, else_bb
, EDGE_FALSE_VALUE
);
634 /* Hashing routine for EDGE_TO_CASES. */
637 edge_to_cases_hash (const void *p
)
639 edge e
= ((struct edge_to_cases_elt
*)p
)->e
;
641 /* Hash on the edge itself (which is a pointer). */
642 return htab_hash_pointer (e
);
645 /* Equality routine for EDGE_TO_CASES, edges are unique, so testing
646 for equality is just a pointer comparison. */
649 edge_to_cases_eq (const void *p1
, const void *p2
)
651 edge e1
= ((struct edge_to_cases_elt
*)p1
)->e
;
652 edge e2
= ((struct edge_to_cases_elt
*)p2
)->e
;
657 /* Called for each element in the hash table (P) as we delete the
658 edge to cases hash table.
660 Clear all the TREE_CHAINs to prevent problems with copying of
661 SWITCH_EXPRs and structure sharing rules, then free the hash table
665 edge_to_cases_cleanup (void *p
)
667 struct edge_to_cases_elt
*elt
= p
;
670 for (t
= elt
->case_labels
; t
; t
= next
)
672 next
= TREE_CHAIN (t
);
673 TREE_CHAIN (t
) = NULL
;
678 /* Start recording information mapping edges to case labels. */
681 start_recording_case_labels (void)
683 gcc_assert (edge_to_cases
== NULL
);
685 edge_to_cases
= htab_create (37,
688 edge_to_cases_cleanup
);
691 /* Return nonzero if we are recording information for case labels. */
694 recording_case_labels_p (void)
696 return (edge_to_cases
!= NULL
);
699 /* Stop recording information mapping edges to case labels and
700 remove any information we have recorded. */
702 end_recording_case_labels (void)
704 htab_delete (edge_to_cases
);
705 edge_to_cases
= NULL
;
708 /* Record that CASE_LABEL (a CASE_LABEL_EXPR) references edge E. */
711 record_switch_edge (edge e
, tree case_label
)
713 struct edge_to_cases_elt
*elt
;
716 /* Build a hash table element so we can see if E is already
718 elt
= xmalloc (sizeof (struct edge_to_cases_elt
));
720 elt
->case_labels
= case_label
;
722 slot
= htab_find_slot (edge_to_cases
, elt
, INSERT
);
726 /* E was not in the hash table. Install E into the hash table. */
731 /* E was already in the hash table. Free ELT as we do not need it
735 /* Get the entry stored in the hash table. */
736 elt
= (struct edge_to_cases_elt
*) *slot
;
738 /* Add it to the chain of CASE_LABEL_EXPRs referencing E. */
739 TREE_CHAIN (case_label
) = elt
->case_labels
;
740 elt
->case_labels
= case_label
;
744 /* If we are inside a {start,end}_recording_cases block, then return
745 a chain of CASE_LABEL_EXPRs from T which reference E.
747 Otherwise return NULL. */
750 get_cases_for_edge (edge e
, tree t
)
752 struct edge_to_cases_elt elt
, *elt_p
;
757 /* If we are not recording cases, then we do not have CASE_LABEL_EXPR
758 chains available. Return NULL so the caller can detect this case. */
759 if (!recording_case_labels_p ())
764 elt
.case_labels
= NULL
;
765 slot
= htab_find_slot (edge_to_cases
, &elt
, NO_INSERT
);
769 elt_p
= (struct edge_to_cases_elt
*)*slot
;
770 return elt_p
->case_labels
;
773 /* If we did not find E in the hash table, then this must be the first
774 time we have been queried for information about E & T. Add all the
775 elements from T to the hash table then perform the query again. */
777 vec
= SWITCH_LABELS (t
);
778 n
= TREE_VEC_LENGTH (vec
);
779 for (i
= 0; i
< n
; i
++)
781 tree lab
= CASE_LABEL (TREE_VEC_ELT (vec
, i
));
782 basic_block label_bb
= label_to_block (lab
);
783 record_switch_edge (find_edge (e
->src
, label_bb
), TREE_VEC_ELT (vec
, i
));
788 /* Create the edges for a SWITCH_EXPR starting at block BB.
789 At this point, the switch body has been lowered and the
790 SWITCH_LABELS filled in, so this is in effect a multi-way branch. */
793 make_switch_expr_edges (basic_block bb
)
795 tree entry
= last_stmt (bb
);
799 vec
= SWITCH_LABELS (entry
);
800 n
= TREE_VEC_LENGTH (vec
);
802 for (i
= 0; i
< n
; ++i
)
804 tree lab
= CASE_LABEL (TREE_VEC_ELT (vec
, i
));
805 basic_block label_bb
= label_to_block (lab
);
806 make_edge (bb
, label_bb
, 0);
811 /* Return the basic block holding label DEST. */
814 label_to_block (tree dest
)
816 int uid
= LABEL_DECL_UID (dest
);
818 /* We would die hard when faced by an undefined label. Emit a label to
819 the very first basic block. This will hopefully make even the dataflow
820 and undefined variable warnings quite right. */
821 if ((errorcount
|| sorrycount
) && uid
< 0)
823 block_stmt_iterator bsi
= bsi_start (BASIC_BLOCK (0));
826 stmt
= build1 (LABEL_EXPR
, void_type_node
, dest
);
827 bsi_insert_before (&bsi
, stmt
, BSI_NEW_STMT
);
828 uid
= LABEL_DECL_UID (dest
);
830 return VARRAY_BB (label_to_block_map
, uid
);
834 /* Create edges for a goto statement at block BB. */
837 make_goto_expr_edges (basic_block bb
)
840 basic_block target_bb
;
842 block_stmt_iterator last
= bsi_last (bb
);
844 goto_t
= bsi_stmt (last
);
846 /* If the last statement is not a GOTO (i.e., it is a RETURN_EXPR,
847 CALL_EXPR or MODIFY_EXPR), then the edge is an abnormal edge resulting
848 from a nonlocal goto. */
849 if (TREE_CODE (goto_t
) != GOTO_EXPR
)
851 dest
= error_mark_node
;
856 dest
= GOTO_DESTINATION (goto_t
);
859 /* A GOTO to a local label creates normal edges. */
860 if (simple_goto_p (goto_t
))
862 edge e
= make_edge (bb
, label_to_block (dest
), EDGE_FALLTHRU
);
863 #ifdef USE_MAPPED_LOCATION
864 e
->goto_locus
= EXPR_LOCATION (goto_t
);
866 e
->goto_locus
= EXPR_LOCUS (goto_t
);
872 /* Nothing more to do for nonlocal gotos. */
873 if (TREE_CODE (dest
) == LABEL_DECL
)
876 /* Computed gotos remain. */
879 /* Look for the block starting with the destination label. In the
880 case of a computed goto, make an edge to any label block we find
882 FOR_EACH_BB (target_bb
)
884 block_stmt_iterator bsi
;
886 for (bsi
= bsi_start (target_bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
888 tree target
= bsi_stmt (bsi
);
890 if (TREE_CODE (target
) != LABEL_EXPR
)
894 /* Computed GOTOs. Make an edge to every label block that has
895 been marked as a potential target for a computed goto. */
896 (FORCED_LABEL (LABEL_EXPR_LABEL (target
)) && for_call
== 0)
897 /* Nonlocal GOTO target. Make an edge to every label block
898 that has been marked as a potential target for a nonlocal
900 || (DECL_NONLOCAL (LABEL_EXPR_LABEL (target
)) && for_call
== 1))
902 make_edge (bb
, target_bb
, EDGE_ABNORMAL
);
908 /* Degenerate case of computed goto with no labels. */
909 if (!for_call
&& EDGE_COUNT (bb
->succs
) == 0)
910 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
914 /*---------------------------------------------------------------------------
916 ---------------------------------------------------------------------------*/
918 /* Remove unreachable blocks and other miscellaneous clean up work. */
921 cleanup_tree_cfg (void)
925 timevar_push (TV_TREE_CLEANUP_CFG
);
927 retval
= cleanup_control_flow ();
928 retval
|= delete_unreachable_blocks ();
930 /* cleanup_forwarder_blocks can redirect edges out of SWITCH_EXPRs,
931 which can get expensive. So we want to enable recording of edge
932 to CASE_LABEL_EXPR mappings around the call to
933 cleanup_forwarder_blocks. */
934 start_recording_case_labels ();
935 retval
|= cleanup_forwarder_blocks ();
936 end_recording_case_labels ();
938 #ifdef ENABLE_CHECKING
941 gcc_assert (!cleanup_control_flow ());
942 gcc_assert (!delete_unreachable_blocks ());
943 gcc_assert (!cleanup_forwarder_blocks ());
947 /* Merging the blocks creates no new opportunities for the other
948 optimizations, so do it here. */
949 retval
|= merge_seq_blocks ();
953 #ifdef ENABLE_CHECKING
956 timevar_pop (TV_TREE_CLEANUP_CFG
);
961 /* Cleanup useless labels in basic blocks. This is something we wish
962 to do early because it allows us to group case labels before creating
963 the edges for the CFG, and it speeds up block statement iterators in
965 We only run this pass once, running it more than once is probably not
968 /* A map from basic block index to the leading label of that block. */
969 static tree
*label_for_bb
;
971 /* Callback for for_each_eh_region. Helper for cleanup_dead_labels. */
973 update_eh_label (struct eh_region
*region
)
975 tree old_label
= get_eh_region_tree_label (region
);
979 basic_block bb
= label_to_block (old_label
);
981 /* ??? After optimizing, there may be EH regions with labels
982 that have already been removed from the function body, so
983 there is no basic block for them. */
987 new_label
= label_for_bb
[bb
->index
];
988 set_eh_region_tree_label (region
, new_label
);
992 /* Given LABEL return the first label in the same basic block. */
994 main_block_label (tree label
)
996 basic_block bb
= label_to_block (label
);
998 /* label_to_block possibly inserted undefined label into the chain. */
999 if (!label_for_bb
[bb
->index
])
1000 label_for_bb
[bb
->index
] = label
;
1001 return label_for_bb
[bb
->index
];
1004 /* Cleanup redundant labels. This is a three-step process:
1005 1) Find the leading label for each block.
1006 2) Redirect all references to labels to the leading labels.
1007 3) Cleanup all useless labels. */
1010 cleanup_dead_labels (void)
1013 label_for_bb
= xcalloc (last_basic_block
, sizeof (tree
));
1015 /* Find a suitable label for each block. We use the first user-defined
1016 label if there is one, or otherwise just the first label we see. */
1019 block_stmt_iterator i
;
1021 for (i
= bsi_start (bb
); !bsi_end_p (i
); bsi_next (&i
))
1023 tree label
, stmt
= bsi_stmt (i
);
1025 if (TREE_CODE (stmt
) != LABEL_EXPR
)
1028 label
= LABEL_EXPR_LABEL (stmt
);
1030 /* If we have not yet seen a label for the current block,
1031 remember this one and see if there are more labels. */
1032 if (! label_for_bb
[bb
->index
])
1034 label_for_bb
[bb
->index
] = label
;
1038 /* If we did see a label for the current block already, but it
1039 is an artificially created label, replace it if the current
1040 label is a user defined label. */
1041 if (! DECL_ARTIFICIAL (label
)
1042 && DECL_ARTIFICIAL (label_for_bb
[bb
->index
]))
1044 label_for_bb
[bb
->index
] = label
;
1050 /* Now redirect all jumps/branches to the selected label.
1051 First do so for each block ending in a control statement. */
1054 tree stmt
= last_stmt (bb
);
1058 switch (TREE_CODE (stmt
))
1062 tree true_branch
, false_branch
;
1064 true_branch
= COND_EXPR_THEN (stmt
);
1065 false_branch
= COND_EXPR_ELSE (stmt
);
1067 GOTO_DESTINATION (true_branch
)
1068 = main_block_label (GOTO_DESTINATION (true_branch
));
1069 GOTO_DESTINATION (false_branch
)
1070 = main_block_label (GOTO_DESTINATION (false_branch
));
1078 tree vec
= SWITCH_LABELS (stmt
);
1079 size_t n
= TREE_VEC_LENGTH (vec
);
1081 /* Replace all destination labels. */
1082 for (i
= 0; i
< n
; ++i
)
1084 tree elt
= TREE_VEC_ELT (vec
, i
);
1085 tree label
= main_block_label (CASE_LABEL (elt
));
1086 CASE_LABEL (elt
) = label
;
1091 /* We have to handle GOTO_EXPRs until they're removed, and we don't
1092 remove them until after we've created the CFG edges. */
1094 if (! computed_goto_p (stmt
))
1096 GOTO_DESTINATION (stmt
)
1097 = main_block_label (GOTO_DESTINATION (stmt
));
1106 for_each_eh_region (update_eh_label
);
1108 /* Finally, purge dead labels. All user-defined labels and labels that
1109 can be the target of non-local gotos are preserved. */
1112 block_stmt_iterator i
;
1113 tree label_for_this_bb
= label_for_bb
[bb
->index
];
1115 if (! label_for_this_bb
)
1118 for (i
= bsi_start (bb
); !bsi_end_p (i
); )
1120 tree label
, stmt
= bsi_stmt (i
);
1122 if (TREE_CODE (stmt
) != LABEL_EXPR
)
1125 label
= LABEL_EXPR_LABEL (stmt
);
1127 if (label
== label_for_this_bb
1128 || ! DECL_ARTIFICIAL (label
)
1129 || DECL_NONLOCAL (label
))
1136 free (label_for_bb
);
1139 /* Look for blocks ending in a multiway branch (a SWITCH_EXPR in GIMPLE),
1140 and scan the sorted vector of cases. Combine the ones jumping to the
1142 Eg. three separate entries 1: 2: 3: become one entry 1..3: */
1145 group_case_labels (void)
1151 tree stmt
= last_stmt (bb
);
1152 if (stmt
&& TREE_CODE (stmt
) == SWITCH_EXPR
)
1154 tree labels
= SWITCH_LABELS (stmt
);
1155 int old_size
= TREE_VEC_LENGTH (labels
);
1156 int i
, j
, new_size
= old_size
;
1157 tree default_case
= TREE_VEC_ELT (labels
, old_size
- 1);
1160 /* The default label is always the last case in a switch
1161 statement after gimplification. */
1162 default_label
= CASE_LABEL (default_case
);
1164 /* Look for possible opportunities to merge cases.
1165 Ignore the last element of the label vector because it
1166 must be the default case. */
1168 while (i
< old_size
- 1)
1170 tree base_case
, base_label
, base_high
, type
;
1171 base_case
= TREE_VEC_ELT (labels
, i
);
1173 gcc_assert (base_case
);
1174 base_label
= CASE_LABEL (base_case
);
1176 /* Discard cases that have the same destination as the
1178 if (base_label
== default_label
)
1180 TREE_VEC_ELT (labels
, i
) = NULL_TREE
;
1186 type
= TREE_TYPE (CASE_LOW (base_case
));
1187 base_high
= CASE_HIGH (base_case
) ?
1188 CASE_HIGH (base_case
) : CASE_LOW (base_case
);
1190 /* Try to merge case labels. Break out when we reach the end
1191 of the label vector or when we cannot merge the next case
1192 label with the current one. */
1193 while (i
< old_size
- 1)
1195 tree merge_case
= TREE_VEC_ELT (labels
, i
);
1196 tree merge_label
= CASE_LABEL (merge_case
);
1197 tree t
= int_const_binop (PLUS_EXPR
, base_high
,
1198 integer_one_node
, 1);
1200 /* Merge the cases if they jump to the same place,
1201 and their ranges are consecutive. */
1202 if (merge_label
== base_label
1203 && tree_int_cst_equal (CASE_LOW (merge_case
), t
))
1205 base_high
= CASE_HIGH (merge_case
) ?
1206 CASE_HIGH (merge_case
) : CASE_LOW (merge_case
);
1207 CASE_HIGH (base_case
) = base_high
;
1208 TREE_VEC_ELT (labels
, i
) = NULL_TREE
;
1217 /* Compress the case labels in the label vector, and adjust the
1218 length of the vector. */
1219 for (i
= 0, j
= 0; i
< new_size
; i
++)
1221 while (! TREE_VEC_ELT (labels
, j
))
1223 TREE_VEC_ELT (labels
, i
) = TREE_VEC_ELT (labels
, j
++);
1225 TREE_VEC_LENGTH (labels
) = new_size
;
1230 /* Checks whether we can merge block B into block A. */
1233 tree_can_merge_blocks_p (basic_block a
, basic_block b
)
1236 block_stmt_iterator bsi
;
1238 if (EDGE_COUNT (a
->succs
) != 1)
1241 if (EDGE_SUCC (a
, 0)->flags
& EDGE_ABNORMAL
)
1244 if (EDGE_SUCC (a
, 0)->dest
!= b
)
1247 if (EDGE_COUNT (b
->preds
) > 1)
1250 if (b
== EXIT_BLOCK_PTR
)
1253 /* If A ends by a statement causing exceptions or something similar, we
1254 cannot merge the blocks. */
1255 stmt
= last_stmt (a
);
1256 if (stmt
&& stmt_ends_bb_p (stmt
))
1259 /* Do not allow a block with only a non-local label to be merged. */
1260 if (stmt
&& TREE_CODE (stmt
) == LABEL_EXPR
1261 && DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt
)))
1264 /* There may be no phi nodes at the start of b. Most of these degenerate
1265 phi nodes should be cleaned up by kill_redundant_phi_nodes. */
1269 /* Do not remove user labels. */
1270 for (bsi
= bsi_start (b
); !bsi_end_p (bsi
); bsi_next (&bsi
))
1272 stmt
= bsi_stmt (bsi
);
1273 if (TREE_CODE (stmt
) != LABEL_EXPR
)
1275 if (!DECL_ARTIFICIAL (LABEL_EXPR_LABEL (stmt
)))
1283 /* Merge block B into block A. */
1286 tree_merge_blocks (basic_block a
, basic_block b
)
1288 block_stmt_iterator bsi
;
1289 tree_stmt_iterator last
;
1292 fprintf (dump_file
, "Merging blocks %d and %d\n", a
->index
, b
->index
);
1294 /* Ensure that B follows A. */
1295 move_block_after (b
, a
);
1297 gcc_assert (EDGE_SUCC (a
, 0)->flags
& EDGE_FALLTHRU
);
1298 gcc_assert (!last_stmt (a
) || !stmt_ends_bb_p (last_stmt (a
)));
1300 /* Remove labels from B and set bb_for_stmt to A for other statements. */
1301 for (bsi
= bsi_start (b
); !bsi_end_p (bsi
);)
1303 if (TREE_CODE (bsi_stmt (bsi
)) == LABEL_EXPR
)
1307 set_bb_for_stmt (bsi_stmt (bsi
), a
);
1312 /* Merge the chains. */
1313 last
= tsi_last (a
->stmt_list
);
1314 tsi_link_after (&last
, b
->stmt_list
, TSI_NEW_STMT
);
1315 b
->stmt_list
= NULL
;
1319 /* Walk the function tree removing unnecessary statements.
1321 * Empty statement nodes are removed
1323 * Unnecessary TRY_FINALLY and TRY_CATCH blocks are removed
1325 * Unnecessary COND_EXPRs are removed
1327 * Some unnecessary BIND_EXPRs are removed
1329 Clearly more work could be done. The trick is doing the analysis
1330 and removal fast enough to be a net improvement in compile times.
1332 Note that when we remove a control structure such as a COND_EXPR
1333 BIND_EXPR, or TRY block, we will need to repeat this optimization pass
1334 to ensure we eliminate all the useless code. */
1345 static void remove_useless_stmts_1 (tree
*, struct rus_data
*);
1348 remove_useless_stmts_warn_notreached (tree stmt
)
1350 if (EXPR_HAS_LOCATION (stmt
))
1352 location_t loc
= EXPR_LOCATION (stmt
);
1353 if (LOCATION_LINE (loc
) > 0)
1355 warning ("%Hwill never be executed", &loc
);
1360 switch (TREE_CODE (stmt
))
1362 case STATEMENT_LIST
:
1364 tree_stmt_iterator i
;
1365 for (i
= tsi_start (stmt
); !tsi_end_p (i
); tsi_next (&i
))
1366 if (remove_useless_stmts_warn_notreached (tsi_stmt (i
)))
1372 if (remove_useless_stmts_warn_notreached (COND_EXPR_COND (stmt
)))
1374 if (remove_useless_stmts_warn_notreached (COND_EXPR_THEN (stmt
)))
1376 if (remove_useless_stmts_warn_notreached (COND_EXPR_ELSE (stmt
)))
1380 case TRY_FINALLY_EXPR
:
1381 case TRY_CATCH_EXPR
:
1382 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt
, 0)))
1384 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt
, 1)))
1389 return remove_useless_stmts_warn_notreached (CATCH_BODY (stmt
));
1390 case EH_FILTER_EXPR
:
1391 return remove_useless_stmts_warn_notreached (EH_FILTER_FAILURE (stmt
));
1393 return remove_useless_stmts_warn_notreached (BIND_EXPR_BLOCK (stmt
));
1396 /* Not a live container. */
1404 remove_useless_stmts_cond (tree
*stmt_p
, struct rus_data
*data
)
1406 tree then_clause
, else_clause
, cond
;
1407 bool save_has_label
, then_has_label
, else_has_label
;
1409 save_has_label
= data
->has_label
;
1410 data
->has_label
= false;
1411 data
->last_goto
= NULL
;
1413 remove_useless_stmts_1 (&COND_EXPR_THEN (*stmt_p
), data
);
1415 then_has_label
= data
->has_label
;
1416 data
->has_label
= false;
1417 data
->last_goto
= NULL
;
1419 remove_useless_stmts_1 (&COND_EXPR_ELSE (*stmt_p
), data
);
1421 else_has_label
= data
->has_label
;
1422 data
->has_label
= save_has_label
| then_has_label
| else_has_label
;
1424 then_clause
= COND_EXPR_THEN (*stmt_p
);
1425 else_clause
= COND_EXPR_ELSE (*stmt_p
);
1426 cond
= fold (COND_EXPR_COND (*stmt_p
));
1428 /* If neither arm does anything at all, we can remove the whole IF. */
1429 if (!TREE_SIDE_EFFECTS (then_clause
) && !TREE_SIDE_EFFECTS (else_clause
))
1431 *stmt_p
= build_empty_stmt ();
1432 data
->repeat
= true;
1435 /* If there are no reachable statements in an arm, then we can
1436 zap the entire conditional. */
1437 else if (integer_nonzerop (cond
) && !else_has_label
)
1439 if (warn_notreached
)
1440 remove_useless_stmts_warn_notreached (else_clause
);
1441 *stmt_p
= then_clause
;
1442 data
->repeat
= true;
1444 else if (integer_zerop (cond
) && !then_has_label
)
1446 if (warn_notreached
)
1447 remove_useless_stmts_warn_notreached (then_clause
);
1448 *stmt_p
= else_clause
;
1449 data
->repeat
= true;
1452 /* Check a couple of simple things on then/else with single stmts. */
1455 tree then_stmt
= expr_only (then_clause
);
1456 tree else_stmt
= expr_only (else_clause
);
1458 /* Notice branches to a common destination. */
1459 if (then_stmt
&& else_stmt
1460 && TREE_CODE (then_stmt
) == GOTO_EXPR
1461 && TREE_CODE (else_stmt
) == GOTO_EXPR
1462 && (GOTO_DESTINATION (then_stmt
) == GOTO_DESTINATION (else_stmt
)))
1464 *stmt_p
= then_stmt
;
1465 data
->repeat
= true;
1468 /* If the THEN/ELSE clause merely assigns a value to a variable or
1469 parameter which is already known to contain that value, then
1470 remove the useless THEN/ELSE clause. */
1471 else if (TREE_CODE (cond
) == VAR_DECL
|| TREE_CODE (cond
) == PARM_DECL
)
1474 && TREE_CODE (else_stmt
) == MODIFY_EXPR
1475 && TREE_OPERAND (else_stmt
, 0) == cond
1476 && integer_zerop (TREE_OPERAND (else_stmt
, 1)))
1477 COND_EXPR_ELSE (*stmt_p
) = alloc_stmt_list ();
1479 else if ((TREE_CODE (cond
) == EQ_EXPR
|| TREE_CODE (cond
) == NE_EXPR
)
1480 && (TREE_CODE (TREE_OPERAND (cond
, 0)) == VAR_DECL
1481 || TREE_CODE (TREE_OPERAND (cond
, 0)) == PARM_DECL
)
1482 && TREE_CONSTANT (TREE_OPERAND (cond
, 1)))
1484 tree stmt
= (TREE_CODE (cond
) == EQ_EXPR
1485 ? then_stmt
: else_stmt
);
1486 tree
*location
= (TREE_CODE (cond
) == EQ_EXPR
1487 ? &COND_EXPR_THEN (*stmt_p
)
1488 : &COND_EXPR_ELSE (*stmt_p
));
1491 && TREE_CODE (stmt
) == MODIFY_EXPR
1492 && TREE_OPERAND (stmt
, 0) == TREE_OPERAND (cond
, 0)
1493 && TREE_OPERAND (stmt
, 1) == TREE_OPERAND (cond
, 1))
1494 *location
= alloc_stmt_list ();
1498 /* Protect GOTOs in the arm of COND_EXPRs from being removed. They
1499 would be re-introduced during lowering. */
1500 data
->last_goto
= NULL
;
1505 remove_useless_stmts_tf (tree
*stmt_p
, struct rus_data
*data
)
1507 bool save_may_branch
, save_may_throw
;
1508 bool this_may_branch
, this_may_throw
;
1510 /* Collect may_branch and may_throw information for the body only. */
1511 save_may_branch
= data
->may_branch
;
1512 save_may_throw
= data
->may_throw
;
1513 data
->may_branch
= false;
1514 data
->may_throw
= false;
1515 data
->last_goto
= NULL
;
1517 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p
, 0), data
);
1519 this_may_branch
= data
->may_branch
;
1520 this_may_throw
= data
->may_throw
;
1521 data
->may_branch
|= save_may_branch
;
1522 data
->may_throw
|= save_may_throw
;
1523 data
->last_goto
= NULL
;
1525 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p
, 1), data
);
1527 /* If the body is empty, then we can emit the FINALLY block without
1528 the enclosing TRY_FINALLY_EXPR. */
1529 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p
, 0)))
1531 *stmt_p
= TREE_OPERAND (*stmt_p
, 1);
1532 data
->repeat
= true;
1535 /* If the handler is empty, then we can emit the TRY block without
1536 the enclosing TRY_FINALLY_EXPR. */
1537 else if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p
, 1)))
1539 *stmt_p
= TREE_OPERAND (*stmt_p
, 0);
1540 data
->repeat
= true;
1543 /* If the body neither throws, nor branches, then we can safely
1544 string the TRY and FINALLY blocks together. */
1545 else if (!this_may_branch
&& !this_may_throw
)
1547 tree stmt
= *stmt_p
;
1548 *stmt_p
= TREE_OPERAND (stmt
, 0);
1549 append_to_statement_list (TREE_OPERAND (stmt
, 1), stmt_p
);
1550 data
->repeat
= true;
1556 remove_useless_stmts_tc (tree
*stmt_p
, struct rus_data
*data
)
1558 bool save_may_throw
, this_may_throw
;
1559 tree_stmt_iterator i
;
1562 /* Collect may_throw information for the body only. */
1563 save_may_throw
= data
->may_throw
;
1564 data
->may_throw
= false;
1565 data
->last_goto
= NULL
;
1567 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p
, 0), data
);
1569 this_may_throw
= data
->may_throw
;
1570 data
->may_throw
= save_may_throw
;
1572 /* If the body cannot throw, then we can drop the entire TRY_CATCH_EXPR. */
1573 if (!this_may_throw
)
1575 if (warn_notreached
)
1576 remove_useless_stmts_warn_notreached (TREE_OPERAND (*stmt_p
, 1));
1577 *stmt_p
= TREE_OPERAND (*stmt_p
, 0);
1578 data
->repeat
= true;
1582 /* Process the catch clause specially. We may be able to tell that
1583 no exceptions propagate past this point. */
1585 this_may_throw
= true;
1586 i
= tsi_start (TREE_OPERAND (*stmt_p
, 1));
1587 stmt
= tsi_stmt (i
);
1588 data
->last_goto
= NULL
;
1590 switch (TREE_CODE (stmt
))
1593 for (; !tsi_end_p (i
); tsi_next (&i
))
1595 stmt
= tsi_stmt (i
);
1596 /* If we catch all exceptions, then the body does not
1597 propagate exceptions past this point. */
1598 if (CATCH_TYPES (stmt
) == NULL
)
1599 this_may_throw
= false;
1600 data
->last_goto
= NULL
;
1601 remove_useless_stmts_1 (&CATCH_BODY (stmt
), data
);
1605 case EH_FILTER_EXPR
:
1606 if (EH_FILTER_MUST_NOT_THROW (stmt
))
1607 this_may_throw
= false;
1608 else if (EH_FILTER_TYPES (stmt
) == NULL
)
1609 this_may_throw
= false;
1610 remove_useless_stmts_1 (&EH_FILTER_FAILURE (stmt
), data
);
1614 /* Otherwise this is a cleanup. */
1615 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p
, 1), data
);
1617 /* If the cleanup is empty, then we can emit the TRY block without
1618 the enclosing TRY_CATCH_EXPR. */
1619 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p
, 1)))
1621 *stmt_p
= TREE_OPERAND (*stmt_p
, 0);
1622 data
->repeat
= true;
1626 data
->may_throw
|= this_may_throw
;
1631 remove_useless_stmts_bind (tree
*stmt_p
, struct rus_data
*data
)
1635 /* First remove anything underneath the BIND_EXPR. */
1636 remove_useless_stmts_1 (&BIND_EXPR_BODY (*stmt_p
), data
);
1638 /* If the BIND_EXPR has no variables, then we can pull everything
1639 up one level and remove the BIND_EXPR, unless this is the toplevel
1640 BIND_EXPR for the current function or an inlined function.
1642 When this situation occurs we will want to apply this
1643 optimization again. */
1644 block
= BIND_EXPR_BLOCK (*stmt_p
);
1645 if (BIND_EXPR_VARS (*stmt_p
) == NULL_TREE
1646 && *stmt_p
!= DECL_SAVED_TREE (current_function_decl
)
1648 || ! BLOCK_ABSTRACT_ORIGIN (block
)
1649 || (TREE_CODE (BLOCK_ABSTRACT_ORIGIN (block
))
1652 *stmt_p
= BIND_EXPR_BODY (*stmt_p
);
1653 data
->repeat
= true;
1659 remove_useless_stmts_goto (tree
*stmt_p
, struct rus_data
*data
)
1661 tree dest
= GOTO_DESTINATION (*stmt_p
);
1663 data
->may_branch
= true;
1664 data
->last_goto
= NULL
;
1666 /* Record the last goto expr, so that we can delete it if unnecessary. */
1667 if (TREE_CODE (dest
) == LABEL_DECL
)
1668 data
->last_goto
= stmt_p
;
1673 remove_useless_stmts_label (tree
*stmt_p
, struct rus_data
*data
)
1675 tree label
= LABEL_EXPR_LABEL (*stmt_p
);
1677 data
->has_label
= true;
1679 /* We do want to jump across non-local label receiver code. */
1680 if (DECL_NONLOCAL (label
))
1681 data
->last_goto
= NULL
;
1683 else if (data
->last_goto
&& GOTO_DESTINATION (*data
->last_goto
) == label
)
1685 *data
->last_goto
= build_empty_stmt ();
1686 data
->repeat
= true;
1689 /* ??? Add something here to delete unused labels. */
1693 /* If the function is "const" or "pure", then clear TREE_SIDE_EFFECTS on its
1694 decl. This allows us to eliminate redundant or useless
1695 calls to "const" functions.
1697 Gimplifier already does the same operation, but we may notice functions
1698 being const and pure once their calls has been gimplified, so we need
1699 to update the flag. */
1702 update_call_expr_flags (tree call
)
1704 tree decl
= get_callee_fndecl (call
);
1707 if (call_expr_flags (call
) & (ECF_CONST
| ECF_PURE
))
1708 TREE_SIDE_EFFECTS (call
) = 0;
1709 if (TREE_NOTHROW (decl
))
1710 TREE_NOTHROW (call
) = 1;
1714 /* T is CALL_EXPR. Set current_function_calls_* flags. */
1717 notice_special_calls (tree t
)
1719 int flags
= call_expr_flags (t
);
1721 if (flags
& ECF_MAY_BE_ALLOCA
)
1722 current_function_calls_alloca
= true;
1723 if (flags
& ECF_RETURNS_TWICE
)
1724 current_function_calls_setjmp
= true;
1728 /* Clear flags set by notice_special_calls. Used by dead code removal
1729 to update the flags. */
1732 clear_special_calls (void)
1734 current_function_calls_alloca
= false;
1735 current_function_calls_setjmp
= false;
1740 remove_useless_stmts_1 (tree
*tp
, struct rus_data
*data
)
1744 switch (TREE_CODE (t
))
1747 remove_useless_stmts_cond (tp
, data
);
1750 case TRY_FINALLY_EXPR
:
1751 remove_useless_stmts_tf (tp
, data
);
1754 case TRY_CATCH_EXPR
:
1755 remove_useless_stmts_tc (tp
, data
);
1759 remove_useless_stmts_bind (tp
, data
);
1763 remove_useless_stmts_goto (tp
, data
);
1767 remove_useless_stmts_label (tp
, data
);
1772 data
->last_goto
= NULL
;
1773 data
->may_branch
= true;
1778 data
->last_goto
= NULL
;
1779 notice_special_calls (t
);
1780 update_call_expr_flags (t
);
1781 if (tree_could_throw_p (t
))
1782 data
->may_throw
= true;
1786 data
->last_goto
= NULL
;
1788 op
= get_call_expr_in (t
);
1791 update_call_expr_flags (op
);
1792 notice_special_calls (op
);
1794 if (tree_could_throw_p (t
))
1795 data
->may_throw
= true;
1798 case STATEMENT_LIST
:
1800 tree_stmt_iterator i
= tsi_start (t
);
1801 while (!tsi_end_p (i
))
1804 if (IS_EMPTY_STMT (t
))
1810 remove_useless_stmts_1 (tsi_stmt_ptr (i
), data
);
1813 if (TREE_CODE (t
) == STATEMENT_LIST
)
1815 tsi_link_before (&i
, t
, TSI_SAME_STMT
);
1825 data
->last_goto
= NULL
;
1829 data
->last_goto
= NULL
;
1835 remove_useless_stmts (void)
1837 struct rus_data data
;
1839 clear_special_calls ();
1843 memset (&data
, 0, sizeof (data
));
1844 remove_useless_stmts_1 (&DECL_SAVED_TREE (current_function_decl
), &data
);
1846 while (data
.repeat
);
1850 struct tree_opt_pass pass_remove_useless_stmts
=
1852 "useless", /* name */
1854 remove_useless_stmts
, /* execute */
1857 0, /* static_pass_number */
1859 PROP_gimple_any
, /* properties_required */
1860 0, /* properties_provided */
1861 0, /* properties_destroyed */
1862 0, /* todo_flags_start */
1863 TODO_dump_func
, /* todo_flags_finish */
1868 /* Remove obviously useless statements in basic block BB. */
1871 cfg_remove_useless_stmts_bb (basic_block bb
)
1873 block_stmt_iterator bsi
;
1874 tree stmt
= NULL_TREE
;
1875 tree cond
, var
= NULL_TREE
, val
= NULL_TREE
;
1876 struct var_ann_d
*ann
;
1878 /* Check whether we come here from a condition, and if so, get the
1880 if (EDGE_COUNT (bb
->preds
) != 1
1881 || !(EDGE_PRED (bb
, 0)->flags
& (EDGE_TRUE_VALUE
| EDGE_FALSE_VALUE
)))
1884 cond
= COND_EXPR_COND (last_stmt (EDGE_PRED (bb
, 0)->src
));
1886 if (TREE_CODE (cond
) == VAR_DECL
|| TREE_CODE (cond
) == PARM_DECL
)
1889 val
= (EDGE_PRED (bb
, 0)->flags
& EDGE_FALSE_VALUE
1890 ? boolean_false_node
: boolean_true_node
);
1892 else if (TREE_CODE (cond
) == TRUTH_NOT_EXPR
1893 && (TREE_CODE (TREE_OPERAND (cond
, 0)) == VAR_DECL
1894 || TREE_CODE (TREE_OPERAND (cond
, 0)) == PARM_DECL
))
1896 var
= TREE_OPERAND (cond
, 0);
1897 val
= (EDGE_PRED (bb
, 0)->flags
& EDGE_FALSE_VALUE
1898 ? boolean_true_node
: boolean_false_node
);
1902 if (EDGE_PRED (bb
, 0)->flags
& EDGE_FALSE_VALUE
)
1903 cond
= invert_truthvalue (cond
);
1904 if (TREE_CODE (cond
) == EQ_EXPR
1905 && (TREE_CODE (TREE_OPERAND (cond
, 0)) == VAR_DECL
1906 || TREE_CODE (TREE_OPERAND (cond
, 0)) == PARM_DECL
)
1907 && (TREE_CODE (TREE_OPERAND (cond
, 1)) == VAR_DECL
1908 || TREE_CODE (TREE_OPERAND (cond
, 1)) == PARM_DECL
1909 || TREE_CONSTANT (TREE_OPERAND (cond
, 1))))
1911 var
= TREE_OPERAND (cond
, 0);
1912 val
= TREE_OPERAND (cond
, 1);
1918 /* Only work for normal local variables. */
1919 ann
= var_ann (var
);
1922 || TREE_ADDRESSABLE (var
))
1925 if (! TREE_CONSTANT (val
))
1927 ann
= var_ann (val
);
1930 || TREE_ADDRESSABLE (val
))
1934 /* Ignore floating point variables, since comparison behaves weird for
1936 if (FLOAT_TYPE_P (TREE_TYPE (var
)))
1939 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
);)
1941 stmt
= bsi_stmt (bsi
);
1943 /* If the THEN/ELSE clause merely assigns a value to a variable/parameter
1944 which is already known to contain that value, then remove the useless
1945 THEN/ELSE clause. */
1946 if (TREE_CODE (stmt
) == MODIFY_EXPR
1947 && TREE_OPERAND (stmt
, 0) == var
1948 && operand_equal_p (val
, TREE_OPERAND (stmt
, 1), 0))
1954 /* Invalidate the var if we encounter something that could modify it.
1955 Likewise for the value it was previously set to. Note that we only
1956 consider values that are either a VAR_DECL or PARM_DECL so we
1957 can test for conflict very simply. */
1958 if (TREE_CODE (stmt
) == ASM_EXPR
1959 || (TREE_CODE (stmt
) == MODIFY_EXPR
1960 && (TREE_OPERAND (stmt
, 0) == var
1961 || TREE_OPERAND (stmt
, 0) == val
)))
1969 /* A CFG-aware version of remove_useless_stmts. */
1972 cfg_remove_useless_stmts (void)
1976 #ifdef ENABLE_CHECKING
1977 verify_flow_info ();
1982 cfg_remove_useless_stmts_bb (bb
);
1987 /* Remove PHI nodes associated with basic block BB and all edges out of BB. */
1990 remove_phi_nodes_and_edges_for_unreachable_block (basic_block bb
)
1994 /* Since this block is no longer reachable, we can just delete all
1995 of its PHI nodes. */
1996 phi
= phi_nodes (bb
);
1999 tree next
= PHI_CHAIN (phi
);
2000 remove_phi_node (phi
, NULL_TREE
);
2004 /* Remove edges to BB's successors. */
2005 while (EDGE_COUNT (bb
->succs
) > 0)
2006 remove_edge (EDGE_SUCC (bb
, 0));
2010 /* Remove statements of basic block BB. */
2013 remove_bb (basic_block bb
)
2015 block_stmt_iterator i
;
2016 #ifdef USE_MAPPED_LOCATION
2017 source_location loc
= UNKNOWN_LOCATION
;
2019 source_locus loc
= 0;
2024 fprintf (dump_file
, "Removing basic block %d\n", bb
->index
);
2025 if (dump_flags
& TDF_DETAILS
)
2027 dump_bb (bb
, dump_file
, 0);
2028 fprintf (dump_file
, "\n");
2032 /* Remove all the instructions in the block. */
2033 for (i
= bsi_start (bb
); !bsi_end_p (i
);)
2035 tree stmt
= bsi_stmt (i
);
2036 if (TREE_CODE (stmt
) == LABEL_EXPR
2037 && FORCED_LABEL (LABEL_EXPR_LABEL (stmt
)))
2039 basic_block new_bb
= bb
->prev_bb
;
2040 block_stmt_iterator new_bsi
= bsi_start (new_bb
);
2043 bsi_insert_before (&new_bsi
, stmt
, BSI_NEW_STMT
);
2047 release_defs (stmt
);
2049 set_bb_for_stmt (stmt
, NULL
);
2053 /* Don't warn for removed gotos. Gotos are often removed due to
2054 jump threading, thus resulting in bogus warnings. Not great,
2055 since this way we lose warnings for gotos in the original
2056 program that are indeed unreachable. */
2057 if (TREE_CODE (stmt
) != GOTO_EXPR
&& EXPR_HAS_LOCATION (stmt
) && !loc
)
2059 #ifdef USE_MAPPED_LOCATION
2060 if (EXPR_HAS_LOCATION (stmt
))
2061 loc
= EXPR_LOCATION (stmt
);
2064 t
= EXPR_LOCUS (stmt
);
2065 if (t
&& LOCATION_LINE (*t
) > 0)
2071 /* If requested, give a warning that the first statement in the
2072 block is unreachable. We walk statements backwards in the
2073 loop above, so the last statement we process is the first statement
2075 #ifdef USE_MAPPED_LOCATION
2076 if (warn_notreached
&& loc
!= UNKNOWN_LOCATION
)
2077 warning ("%Hwill never be executed", &loc
);
2079 if (warn_notreached
&& loc
)
2080 warning ("%Hwill never be executed", loc
);
2083 remove_phi_nodes_and_edges_for_unreachable_block (bb
);
2086 /* A list of all the noreturn calls passed to modify_stmt.
2087 cleanup_control_flow uses it to detect cases where a mid-block
2088 indirect call has been turned into a noreturn call. When this
2089 happens, all the instructions after the call are no longer
2090 reachable and must be deleted as dead. */
2092 VEC(tree
) *modified_noreturn_calls
;
2094 /* Try to remove superfluous control structures. */
2097 cleanup_control_flow (void)
2100 block_stmt_iterator bsi
;
2101 bool retval
= false;
2104 /* Detect cases where a mid-block call is now known not to return. */
2105 while (VEC_length (tree
, modified_noreturn_calls
))
2107 stmt
= VEC_pop (tree
, modified_noreturn_calls
);
2108 bb
= bb_for_stmt (stmt
);
2109 if (bb
!= NULL
&& last_stmt (bb
) != stmt
&& noreturn_call_p (stmt
))
2110 split_block (bb
, stmt
);
2115 bsi
= bsi_last (bb
);
2117 if (bsi_end_p (bsi
))
2120 stmt
= bsi_stmt (bsi
);
2121 if (TREE_CODE (stmt
) == COND_EXPR
2122 || TREE_CODE (stmt
) == SWITCH_EXPR
)
2123 retval
|= cleanup_control_expr_graph (bb
, bsi
);
2125 /* Check for indirect calls that have been turned into
2127 if (noreturn_call_p (stmt
) && remove_fallthru_edge (bb
->succs
))
2129 free_dominance_info (CDI_DOMINATORS
);
2137 /* Disconnect an unreachable block in the control expression starting
2141 cleanup_control_expr_graph (basic_block bb
, block_stmt_iterator bsi
)
2144 bool retval
= false;
2145 tree expr
= bsi_stmt (bsi
), val
;
2147 if (EDGE_COUNT (bb
->succs
) > 1)
2152 switch (TREE_CODE (expr
))
2155 val
= COND_EXPR_COND (expr
);
2159 val
= SWITCH_COND (expr
);
2160 if (TREE_CODE (val
) != INTEGER_CST
)
2168 taken_edge
= find_taken_edge (bb
, val
);
2172 /* Remove all the edges except the one that is always executed. */
2173 for (ei
= ei_start (bb
->succs
); (e
= ei_safe_edge (ei
)); )
2175 if (e
!= taken_edge
)
2177 taken_edge
->probability
+= e
->probability
;
2178 taken_edge
->count
+= e
->count
;
2185 if (taken_edge
->probability
> REG_BR_PROB_BASE
)
2186 taken_edge
->probability
= REG_BR_PROB_BASE
;
2189 taken_edge
= EDGE_SUCC (bb
, 0);
2192 taken_edge
->flags
= EDGE_FALLTHRU
;
2194 /* We removed some paths from the cfg. */
2195 free_dominance_info (CDI_DOMINATORS
);
2200 /* Remove any fallthru edge from EV. Return true if an edge was removed. */
2203 remove_fallthru_edge (VEC(edge
) *ev
)
2208 FOR_EACH_EDGE (e
, ei
, ev
)
2209 if ((e
->flags
& EDGE_FALLTHRU
) != 0)
2217 /* Given a basic block BB ending with COND_EXPR or SWITCH_EXPR, and a
2218 predicate VAL, return the edge that will be taken out of the block.
2219 If VAL does not match a unique edge, NULL is returned. */
2222 find_taken_edge (basic_block bb
, tree val
)
2226 stmt
= last_stmt (bb
);
2229 gcc_assert (is_ctrl_stmt (stmt
));
2232 if (TREE_CODE (val
) != INTEGER_CST
)
2235 if (TREE_CODE (stmt
) == COND_EXPR
)
2236 return find_taken_edge_cond_expr (bb
, val
);
2238 if (TREE_CODE (stmt
) == SWITCH_EXPR
)
2239 return find_taken_edge_switch_expr (bb
, val
);
2245 /* Given a constant value VAL and the entry block BB to a COND_EXPR
2246 statement, determine which of the two edges will be taken out of the
2247 block. Return NULL if either edge may be taken. */
2250 find_taken_edge_cond_expr (basic_block bb
, tree val
)
2252 edge true_edge
, false_edge
;
2254 extract_true_false_edges_from_block (bb
, &true_edge
, &false_edge
);
2256 /* Otherwise, try to determine which branch of the if() will be taken.
2257 If VAL is a constant but it can't be reduced to a 0 or a 1, then
2258 we don't really know which edge will be taken at runtime. This
2259 may happen when comparing addresses (e.g., if (&var1 == 4)). */
2260 if (integer_nonzerop (val
))
2262 else if (integer_zerop (val
))
2269 /* Given an INTEGER_CST VAL and the entry block BB to a SWITCH_EXPR
2270 statement, determine which edge will be taken out of the block. Return
2271 NULL if any edge may be taken. */
2274 find_taken_edge_switch_expr (basic_block bb
, tree val
)
2276 tree switch_expr
, taken_case
;
2277 basic_block dest_bb
;
2280 switch_expr
= last_stmt (bb
);
2281 taken_case
= find_case_label_for_value (switch_expr
, val
);
2282 dest_bb
= label_to_block (CASE_LABEL (taken_case
));
2284 e
= find_edge (bb
, dest_bb
);
2290 /* Return the CASE_LABEL_EXPR that SWITCH_EXPR will take for VAL.
2291 We can make optimal use here of the fact that the case labels are
2292 sorted: We can do a binary search for a case matching VAL. */
2295 find_case_label_for_value (tree switch_expr
, tree val
)
2297 tree vec
= SWITCH_LABELS (switch_expr
);
2298 size_t low
, high
, n
= TREE_VEC_LENGTH (vec
);
2299 tree default_case
= TREE_VEC_ELT (vec
, n
- 1);
2301 for (low
= -1, high
= n
- 1; high
- low
> 1; )
2303 size_t i
= (high
+ low
) / 2;
2304 tree t
= TREE_VEC_ELT (vec
, i
);
2307 /* Cache the result of comparing CASE_LOW and val. */
2308 cmp
= tree_int_cst_compare (CASE_LOW (t
), val
);
2315 if (CASE_HIGH (t
) == NULL
)
2317 /* A singe-valued case label. */
2323 /* A case range. We can only handle integer ranges. */
2324 if (cmp
<= 0 && tree_int_cst_compare (CASE_HIGH (t
), val
) >= 0)
2329 return default_case
;
2333 /* If all the PHI nodes in DEST have alternatives for E1 and E2 and
2334 those alternatives are equal in each of the PHI nodes, then return
2335 true, else return false. */
2338 phi_alternatives_equal (basic_block dest
, edge e1
, edge e2
)
2340 int n1
= e1
->dest_idx
;
2341 int n2
= e2
->dest_idx
;
2344 for (phi
= phi_nodes (dest
); phi
; phi
= PHI_CHAIN (phi
))
2346 tree val1
= PHI_ARG_DEF (phi
, n1
);
2347 tree val2
= PHI_ARG_DEF (phi
, n2
);
2349 gcc_assert (val1
!= NULL_TREE
);
2350 gcc_assert (val2
!= NULL_TREE
);
2352 if (!operand_equal_for_phi_arg_p (val1
, val2
))
2360 /*---------------------------------------------------------------------------
2362 ---------------------------------------------------------------------------*/
2364 /* Dump tree-specific information of block BB to file OUTF. */
2367 tree_dump_bb (basic_block bb
, FILE *outf
, int indent
)
2369 dump_generic_bb (outf
, bb
, indent
, TDF_VOPS
);
2373 /* Dump a basic block on stderr. */
2376 debug_tree_bb (basic_block bb
)
2378 dump_bb (bb
, stderr
, 0);
2382 /* Dump basic block with index N on stderr. */
2385 debug_tree_bb_n (int n
)
2387 debug_tree_bb (BASIC_BLOCK (n
));
2388 return BASIC_BLOCK (n
);
2392 /* Dump the CFG on stderr.
2394 FLAGS are the same used by the tree dumping functions
2395 (see TDF_* in tree.h). */
2398 debug_tree_cfg (int flags
)
2400 dump_tree_cfg (stderr
, flags
);
2404 /* Dump the program showing basic block boundaries on the given FILE.
2406 FLAGS are the same used by the tree dumping functions (see TDF_* in
2410 dump_tree_cfg (FILE *file
, int flags
)
2412 if (flags
& TDF_DETAILS
)
2414 const char *funcname
2415 = lang_hooks
.decl_printable_name (current_function_decl
, 2);
2418 fprintf (file
, ";; Function %s\n\n", funcname
);
2419 fprintf (file
, ";; \n%d basic blocks, %d edges, last basic block %d.\n\n",
2420 n_basic_blocks
, n_edges
, last_basic_block
);
2422 brief_dump_cfg (file
);
2423 fprintf (file
, "\n");
2426 if (flags
& TDF_STATS
)
2427 dump_cfg_stats (file
);
2429 dump_function_to_file (current_function_decl
, file
, flags
| TDF_BLOCKS
);
2433 /* Dump CFG statistics on FILE. */
2436 dump_cfg_stats (FILE *file
)
2438 static long max_num_merged_labels
= 0;
2439 unsigned long size
, total
= 0;
2442 const char * const fmt_str
= "%-30s%-13s%12s\n";
2443 const char * const fmt_str_1
= "%-30s%13d%11lu%c\n";
2444 const char * const fmt_str_3
= "%-43s%11lu%c\n";
2445 const char *funcname
2446 = lang_hooks
.decl_printable_name (current_function_decl
, 2);
2449 fprintf (file
, "\nCFG Statistics for %s\n\n", funcname
);
2451 fprintf (file
, "---------------------------------------------------------\n");
2452 fprintf (file
, fmt_str
, "", " Number of ", "Memory");
2453 fprintf (file
, fmt_str
, "", " instances ", "used ");
2454 fprintf (file
, "---------------------------------------------------------\n");
2456 size
= n_basic_blocks
* sizeof (struct basic_block_def
);
2458 fprintf (file
, fmt_str_1
, "Basic blocks", n_basic_blocks
,
2459 SCALE (size
), LABEL (size
));
2463 n_edges
+= EDGE_COUNT (bb
->succs
);
2464 size
= n_edges
* sizeof (struct edge_def
);
2466 fprintf (file
, fmt_str_1
, "Edges", n_edges
, SCALE (size
), LABEL (size
));
2468 size
= n_basic_blocks
* sizeof (struct bb_ann_d
);
2470 fprintf (file
, fmt_str_1
, "Basic block annotations", n_basic_blocks
,
2471 SCALE (size
), LABEL (size
));
2473 fprintf (file
, "---------------------------------------------------------\n");
2474 fprintf (file
, fmt_str_3
, "Total memory used by CFG data", SCALE (total
),
2476 fprintf (file
, "---------------------------------------------------------\n");
2477 fprintf (file
, "\n");
2479 if (cfg_stats
.num_merged_labels
> max_num_merged_labels
)
2480 max_num_merged_labels
= cfg_stats
.num_merged_labels
;
2482 fprintf (file
, "Coalesced label blocks: %ld (Max so far: %ld)\n",
2483 cfg_stats
.num_merged_labels
, max_num_merged_labels
);
2485 fprintf (file
, "\n");
2489 /* Dump CFG statistics on stderr. Keep extern so that it's always
2490 linked in the final executable. */
2493 debug_cfg_stats (void)
2495 dump_cfg_stats (stderr
);
2499 /* Dump the flowgraph to a .vcg FILE. */
2502 tree_cfg2vcg (FILE *file
)
2507 const char *funcname
2508 = lang_hooks
.decl_printable_name (current_function_decl
, 2);
2510 /* Write the file header. */
2511 fprintf (file
, "graph: { title: \"%s\"\n", funcname
);
2512 fprintf (file
, "node: { title: \"ENTRY\" label: \"ENTRY\" }\n");
2513 fprintf (file
, "node: { title: \"EXIT\" label: \"EXIT\" }\n");
2515 /* Write blocks and edges. */
2516 FOR_EACH_EDGE (e
, ei
, ENTRY_BLOCK_PTR
->succs
)
2518 fprintf (file
, "edge: { sourcename: \"ENTRY\" targetname: \"%d\"",
2521 if (e
->flags
& EDGE_FAKE
)
2522 fprintf (file
, " linestyle: dotted priority: 10");
2524 fprintf (file
, " linestyle: solid priority: 100");
2526 fprintf (file
, " }\n");
2532 enum tree_code head_code
, end_code
;
2533 const char *head_name
, *end_name
;
2536 tree first
= first_stmt (bb
);
2537 tree last
= last_stmt (bb
);
2541 head_code
= TREE_CODE (first
);
2542 head_name
= tree_code_name
[head_code
];
2543 head_line
= get_lineno (first
);
2546 head_name
= "no-statement";
2550 end_code
= TREE_CODE (last
);
2551 end_name
= tree_code_name
[end_code
];
2552 end_line
= get_lineno (last
);
2555 end_name
= "no-statement";
2557 fprintf (file
, "node: { title: \"%d\" label: \"#%d\\n%s (%d)\\n%s (%d)\"}\n",
2558 bb
->index
, bb
->index
, head_name
, head_line
, end_name
,
2561 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
2563 if (e
->dest
== EXIT_BLOCK_PTR
)
2564 fprintf (file
, "edge: { sourcename: \"%d\" targetname: \"EXIT\"", bb
->index
);
2566 fprintf (file
, "edge: { sourcename: \"%d\" targetname: \"%d\"", bb
->index
, e
->dest
->index
);
2568 if (e
->flags
& EDGE_FAKE
)
2569 fprintf (file
, " priority: 10 linestyle: dotted");
2571 fprintf (file
, " priority: 100 linestyle: solid");
2573 fprintf (file
, " }\n");
2576 if (bb
->next_bb
!= EXIT_BLOCK_PTR
)
2580 fputs ("}\n\n", file
);
2585 /*---------------------------------------------------------------------------
2586 Miscellaneous helpers
2587 ---------------------------------------------------------------------------*/
2589 /* Return true if T represents a stmt that always transfers control. */
2592 is_ctrl_stmt (tree t
)
2594 return (TREE_CODE (t
) == COND_EXPR
2595 || TREE_CODE (t
) == SWITCH_EXPR
2596 || TREE_CODE (t
) == GOTO_EXPR
2597 || TREE_CODE (t
) == RETURN_EXPR
2598 || TREE_CODE (t
) == RESX_EXPR
);
2602 /* Return true if T is a statement that may alter the flow of control
2603 (e.g., a call to a non-returning function). */
2606 is_ctrl_altering_stmt (tree t
)
2611 call
= get_call_expr_in (t
);
2614 /* A non-pure/const CALL_EXPR alters flow control if the current
2615 function has nonlocal labels. */
2616 if (TREE_SIDE_EFFECTS (call
) && current_function_has_nonlocal_label
)
2619 /* A CALL_EXPR also alters control flow if it does not return. */
2620 if (call_expr_flags (call
) & ECF_NORETURN
)
2624 /* If a statement can throw, it alters control flow. */
2625 return tree_can_throw_internal (t
);
2629 /* Return true if T is a computed goto. */
2632 computed_goto_p (tree t
)
2634 return (TREE_CODE (t
) == GOTO_EXPR
2635 && TREE_CODE (GOTO_DESTINATION (t
)) != LABEL_DECL
);
2639 /* Checks whether EXPR is a simple local goto. */
2642 simple_goto_p (tree expr
)
2644 return (TREE_CODE (expr
) == GOTO_EXPR
2645 && TREE_CODE (GOTO_DESTINATION (expr
)) == LABEL_DECL
);
2649 /* Return true if T should start a new basic block. PREV_T is the
2650 statement preceding T. It is used when T is a label or a case label.
2651 Labels should only start a new basic block if their previous statement
2652 wasn't a label. Otherwise, sequence of labels would generate
2653 unnecessary basic blocks that only contain a single label. */
2656 stmt_starts_bb_p (tree t
, tree prev_t
)
2661 /* LABEL_EXPRs start a new basic block only if the preceding
2662 statement wasn't a label of the same type. This prevents the
2663 creation of consecutive blocks that have nothing but a single
2665 if (TREE_CODE (t
) == LABEL_EXPR
)
2667 /* Nonlocal and computed GOTO targets always start a new block. */
2668 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (t
))
2669 || FORCED_LABEL (LABEL_EXPR_LABEL (t
)))
2672 if (prev_t
&& TREE_CODE (prev_t
) == LABEL_EXPR
)
2674 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (prev_t
)))
2677 cfg_stats
.num_merged_labels
++;
2688 /* Return true if T should end a basic block. */
2691 stmt_ends_bb_p (tree t
)
2693 return is_ctrl_stmt (t
) || is_ctrl_altering_stmt (t
);
2697 /* Add gotos that used to be represented implicitly in the CFG. */
2700 disband_implicit_edges (void)
2703 block_stmt_iterator last
;
2710 last
= bsi_last (bb
);
2711 stmt
= last_stmt (bb
);
2713 if (stmt
&& TREE_CODE (stmt
) == COND_EXPR
)
2715 /* Remove superfluous gotos from COND_EXPR branches. Moved
2716 from cfg_remove_useless_stmts here since it violates the
2717 invariants for tree--cfg correspondence and thus fits better
2718 here where we do it anyway. */
2719 e
= find_edge (bb
, bb
->next_bb
);
2722 if (e
->flags
& EDGE_TRUE_VALUE
)
2723 COND_EXPR_THEN (stmt
) = build_empty_stmt ();
2724 else if (e
->flags
& EDGE_FALSE_VALUE
)
2725 COND_EXPR_ELSE (stmt
) = build_empty_stmt ();
2728 e
->flags
|= EDGE_FALLTHRU
;
2734 if (stmt
&& TREE_CODE (stmt
) == RETURN_EXPR
)
2736 /* Remove the RETURN_EXPR if we may fall though to the exit
2738 gcc_assert (EDGE_COUNT (bb
->succs
) == 1);
2739 gcc_assert (EDGE_SUCC (bb
, 0)->dest
== EXIT_BLOCK_PTR
);
2741 if (bb
->next_bb
== EXIT_BLOCK_PTR
2742 && !TREE_OPERAND (stmt
, 0))
2745 EDGE_SUCC (bb
, 0)->flags
|= EDGE_FALLTHRU
;
2750 /* There can be no fallthru edge if the last statement is a control
2752 if (stmt
&& is_ctrl_stmt (stmt
))
2755 /* Find a fallthru edge and emit the goto if necessary. */
2756 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
2757 if (e
->flags
& EDGE_FALLTHRU
)
2760 if (!e
|| e
->dest
== bb
->next_bb
)
2763 gcc_assert (e
->dest
!= EXIT_BLOCK_PTR
);
2764 label
= tree_block_label (e
->dest
);
2766 stmt
= build1 (GOTO_EXPR
, void_type_node
, label
);
2767 #ifdef USE_MAPPED_LOCATION
2768 SET_EXPR_LOCATION (stmt
, e
->goto_locus
);
2770 SET_EXPR_LOCUS (stmt
, e
->goto_locus
);
2772 bsi_insert_after (&last
, stmt
, BSI_NEW_STMT
);
2773 e
->flags
&= ~EDGE_FALLTHRU
;
2777 /* Remove block annotations and other datastructures. */
2780 delete_tree_cfg_annotations (void)
2783 if (n_basic_blocks
> 0)
2784 free_blocks_annotations ();
2786 label_to_block_map
= NULL
;
2793 /* Return the first statement in basic block BB. */
2796 first_stmt (basic_block bb
)
2798 block_stmt_iterator i
= bsi_start (bb
);
2799 return !bsi_end_p (i
) ? bsi_stmt (i
) : NULL_TREE
;
2803 /* Return the last statement in basic block BB. */
2806 last_stmt (basic_block bb
)
2808 block_stmt_iterator b
= bsi_last (bb
);
2809 return !bsi_end_p (b
) ? bsi_stmt (b
) : NULL_TREE
;
2813 /* Return a pointer to the last statement in block BB. */
2816 last_stmt_ptr (basic_block bb
)
2818 block_stmt_iterator last
= bsi_last (bb
);
2819 return !bsi_end_p (last
) ? bsi_stmt_ptr (last
) : NULL
;
2823 /* Return the last statement of an otherwise empty block. Return NULL
2824 if the block is totally empty, or if it contains more than one
2828 last_and_only_stmt (basic_block bb
)
2830 block_stmt_iterator i
= bsi_last (bb
);
2836 last
= bsi_stmt (i
);
2841 /* Empty statements should no longer appear in the instruction stream.
2842 Everything that might have appeared before should be deleted by
2843 remove_useless_stmts, and the optimizers should just bsi_remove
2844 instead of smashing with build_empty_stmt.
2846 Thus the only thing that should appear here in a block containing
2847 one executable statement is a label. */
2848 prev
= bsi_stmt (i
);
2849 if (TREE_CODE (prev
) == LABEL_EXPR
)
2856 /* Mark BB as the basic block holding statement T. */
2859 set_bb_for_stmt (tree t
, basic_block bb
)
2861 if (TREE_CODE (t
) == PHI_NODE
)
2863 else if (TREE_CODE (t
) == STATEMENT_LIST
)
2865 tree_stmt_iterator i
;
2866 for (i
= tsi_start (t
); !tsi_end_p (i
); tsi_next (&i
))
2867 set_bb_for_stmt (tsi_stmt (i
), bb
);
2871 stmt_ann_t ann
= get_stmt_ann (t
);
2874 /* If the statement is a label, add the label to block-to-labels map
2875 so that we can speed up edge creation for GOTO_EXPRs. */
2876 if (TREE_CODE (t
) == LABEL_EXPR
)
2880 t
= LABEL_EXPR_LABEL (t
);
2881 uid
= LABEL_DECL_UID (t
);
2884 LABEL_DECL_UID (t
) = uid
= cfun
->last_label_uid
++;
2885 if (VARRAY_SIZE (label_to_block_map
) <= (unsigned) uid
)
2886 VARRAY_GROW (label_to_block_map
, 3 * uid
/ 2);
2889 /* We're moving an existing label. Make sure that we've
2890 removed it from the old block. */
2891 gcc_assert (!bb
|| !VARRAY_BB (label_to_block_map
, uid
));
2892 VARRAY_BB (label_to_block_map
, uid
) = bb
;
2897 /* Finds iterator for STMT. */
2899 extern block_stmt_iterator
2900 bsi_for_stmt (tree stmt
)
2902 block_stmt_iterator bsi
;
2904 for (bsi
= bsi_start (bb_for_stmt (stmt
)); !bsi_end_p (bsi
); bsi_next (&bsi
))
2905 if (bsi_stmt (bsi
) == stmt
)
2911 /* Insert statement (or statement list) T before the statement
2912 pointed-to by iterator I. M specifies how to update iterator I
2913 after insertion (see enum bsi_iterator_update). */
2916 bsi_insert_before (block_stmt_iterator
*i
, tree t
, enum bsi_iterator_update m
)
2918 set_bb_for_stmt (t
, i
->bb
);
2919 tsi_link_before (&i
->tsi
, t
, m
);
2924 /* Insert statement (or statement list) T after the statement
2925 pointed-to by iterator I. M specifies how to update iterator I
2926 after insertion (see enum bsi_iterator_update). */
2929 bsi_insert_after (block_stmt_iterator
*i
, tree t
, enum bsi_iterator_update m
)
2931 set_bb_for_stmt (t
, i
->bb
);
2932 tsi_link_after (&i
->tsi
, t
, m
);
2937 /* Remove the statement pointed to by iterator I. The iterator is updated
2938 to the next statement. */
2941 bsi_remove (block_stmt_iterator
*i
)
2943 tree t
= bsi_stmt (*i
);
2944 set_bb_for_stmt (t
, NULL
);
2945 tsi_delink (&i
->tsi
);
2949 /* Move the statement at FROM so it comes right after the statement at TO. */
2952 bsi_move_after (block_stmt_iterator
*from
, block_stmt_iterator
*to
)
2954 tree stmt
= bsi_stmt (*from
);
2956 bsi_insert_after (to
, stmt
, BSI_SAME_STMT
);
2960 /* Move the statement at FROM so it comes right before the statement at TO. */
2963 bsi_move_before (block_stmt_iterator
*from
, block_stmt_iterator
*to
)
2965 tree stmt
= bsi_stmt (*from
);
2967 bsi_insert_before (to
, stmt
, BSI_SAME_STMT
);
2971 /* Move the statement at FROM to the end of basic block BB. */
2974 bsi_move_to_bb_end (block_stmt_iterator
*from
, basic_block bb
)
2976 block_stmt_iterator last
= bsi_last (bb
);
2978 /* Have to check bsi_end_p because it could be an empty block. */
2979 if (!bsi_end_p (last
) && is_ctrl_stmt (bsi_stmt (last
)))
2980 bsi_move_before (from
, &last
);
2982 bsi_move_after (from
, &last
);
2986 /* Replace the contents of the statement pointed to by iterator BSI
2987 with STMT. If PRESERVE_EH_INFO is true, the exception handling
2988 information of the original statement is preserved. */
2991 bsi_replace (const block_stmt_iterator
*bsi
, tree stmt
, bool preserve_eh_info
)
2994 tree orig_stmt
= bsi_stmt (*bsi
);
2996 SET_EXPR_LOCUS (stmt
, EXPR_LOCUS (orig_stmt
));
2997 set_bb_for_stmt (stmt
, bsi
->bb
);
2999 /* Preserve EH region information from the original statement, if
3000 requested by the caller. */
3001 if (preserve_eh_info
)
3003 eh_region
= lookup_stmt_eh_region (orig_stmt
);
3005 add_stmt_to_eh_region (stmt
, eh_region
);
3008 *bsi_stmt_ptr (*bsi
) = stmt
;
3013 /* Insert the statement pointed-to by BSI into edge E. Every attempt
3014 is made to place the statement in an existing basic block, but
3015 sometimes that isn't possible. When it isn't possible, the edge is
3016 split and the statement is added to the new block.
3018 In all cases, the returned *BSI points to the correct location. The
3019 return value is true if insertion should be done after the location,
3020 or false if it should be done before the location. If new basic block
3021 has to be created, it is stored in *NEW_BB. */
3024 tree_find_edge_insert_loc (edge e
, block_stmt_iterator
*bsi
,
3025 basic_block
*new_bb
)
3027 basic_block dest
, src
;
3033 /* If the destination has one predecessor which has no PHI nodes,
3034 insert there. Except for the exit block.
3036 The requirement for no PHI nodes could be relaxed. Basically we
3037 would have to examine the PHIs to prove that none of them used
3038 the value set by the statement we want to insert on E. That
3039 hardly seems worth the effort. */
3040 if (EDGE_COUNT (dest
->preds
) == 1
3041 && ! phi_nodes (dest
)
3042 && dest
!= EXIT_BLOCK_PTR
)
3044 *bsi
= bsi_start (dest
);
3045 if (bsi_end_p (*bsi
))
3048 /* Make sure we insert after any leading labels. */
3049 tmp
= bsi_stmt (*bsi
);
3050 while (TREE_CODE (tmp
) == LABEL_EXPR
)
3053 if (bsi_end_p (*bsi
))
3055 tmp
= bsi_stmt (*bsi
);
3058 if (bsi_end_p (*bsi
))
3060 *bsi
= bsi_last (dest
);
3067 /* If the source has one successor, the edge is not abnormal and
3068 the last statement does not end a basic block, insert there.
3069 Except for the entry block. */
3071 if ((e
->flags
& EDGE_ABNORMAL
) == 0
3072 && EDGE_COUNT (src
->succs
) == 1
3073 && src
!= ENTRY_BLOCK_PTR
)
3075 *bsi
= bsi_last (src
);
3076 if (bsi_end_p (*bsi
))
3079 tmp
= bsi_stmt (*bsi
);
3080 if (!stmt_ends_bb_p (tmp
))
3083 /* Insert code just before returning the value. We may need to decompose
3084 the return in the case it contains non-trivial operand. */
3085 if (TREE_CODE (tmp
) == RETURN_EXPR
)
3087 tree op
= TREE_OPERAND (tmp
, 0);
3088 if (!is_gimple_val (op
))
3090 gcc_assert (TREE_CODE (op
) == MODIFY_EXPR
);
3091 bsi_insert_before (bsi
, op
, BSI_NEW_STMT
);
3092 TREE_OPERAND (tmp
, 0) = TREE_OPERAND (op
, 0);
3099 /* Otherwise, create a new basic block, and split this edge. */
3100 dest
= split_edge (e
);
3103 e
= EDGE_PRED (dest
, 0);
3108 /* This routine will commit all pending edge insertions, creating any new
3109 basic blocks which are necessary. */
3112 bsi_commit_edge_inserts (void)
3118 bsi_commit_one_edge_insert (EDGE_SUCC (ENTRY_BLOCK_PTR
, 0), NULL
);
3121 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
3122 bsi_commit_one_edge_insert (e
, NULL
);
3126 /* Commit insertions pending at edge E. If a new block is created, set NEW_BB
3127 to this block, otherwise set it to NULL. */
3130 bsi_commit_one_edge_insert (edge e
, basic_block
*new_bb
)
3134 if (PENDING_STMT (e
))
3136 block_stmt_iterator bsi
;
3137 tree stmt
= PENDING_STMT (e
);
3139 PENDING_STMT (e
) = NULL_TREE
;
3141 if (tree_find_edge_insert_loc (e
, &bsi
, new_bb
))
3142 bsi_insert_after (&bsi
, stmt
, BSI_NEW_STMT
);
3144 bsi_insert_before (&bsi
, stmt
, BSI_NEW_STMT
);
3149 /* Add STMT to the pending list of edge E. No actual insertion is
3150 made until a call to bsi_commit_edge_inserts () is made. */
3153 bsi_insert_on_edge (edge e
, tree stmt
)
3155 append_to_statement_list (stmt
, &PENDING_STMT (e
));
3158 /* Similar to bsi_insert_on_edge+bsi_commit_edge_inserts. If a new
3159 block has to be created, it is returned. */
3162 bsi_insert_on_edge_immediate (edge e
, tree stmt
)
3164 block_stmt_iterator bsi
;
3165 basic_block new_bb
= NULL
;
3167 gcc_assert (!PENDING_STMT (e
));
3169 if (tree_find_edge_insert_loc (e
, &bsi
, &new_bb
))
3170 bsi_insert_after (&bsi
, stmt
, BSI_NEW_STMT
);
3172 bsi_insert_before (&bsi
, stmt
, BSI_NEW_STMT
);
3177 /*---------------------------------------------------------------------------
3178 Tree specific functions for CFG manipulation
3179 ---------------------------------------------------------------------------*/
3181 /* Reinstall those PHI arguments queued in OLD_EDGE to NEW_EDGE. */
3184 reinstall_phi_args (edge new_edge
, edge old_edge
)
3188 if (!PENDING_STMT (old_edge
))
3191 for (var
= PENDING_STMT (old_edge
), phi
= phi_nodes (new_edge
->dest
);
3193 var
= TREE_CHAIN (var
), phi
= PHI_CHAIN (phi
))
3195 tree result
= TREE_PURPOSE (var
);
3196 tree arg
= TREE_VALUE (var
);
3198 gcc_assert (result
== PHI_RESULT (phi
));
3200 add_phi_arg (phi
, arg
, new_edge
);
3203 PENDING_STMT (old_edge
) = NULL
;
3206 /* Split a (typically critical) edge EDGE_IN. Return the new block.
3207 Abort on abnormal edges. */
3210 tree_split_edge (edge edge_in
)
3212 basic_block new_bb
, after_bb
, dest
, src
;
3215 /* Abnormal edges cannot be split. */
3216 gcc_assert (!(edge_in
->flags
& EDGE_ABNORMAL
));
3219 dest
= edge_in
->dest
;
3221 /* Place the new block in the block list. Try to keep the new block
3222 near its "logical" location. This is of most help to humans looking
3223 at debugging dumps. */
3224 if (dest
->prev_bb
&& find_edge (dest
->prev_bb
, dest
))
3225 after_bb
= edge_in
->src
;
3227 after_bb
= dest
->prev_bb
;
3229 new_bb
= create_empty_bb (after_bb
);
3230 new_bb
->frequency
= EDGE_FREQUENCY (edge_in
);
3231 new_bb
->count
= edge_in
->count
;
3232 new_edge
= make_edge (new_bb
, dest
, EDGE_FALLTHRU
);
3233 new_edge
->probability
= REG_BR_PROB_BASE
;
3234 new_edge
->count
= edge_in
->count
;
3236 e
= redirect_edge_and_branch (edge_in
, new_bb
);
3238 reinstall_phi_args (new_edge
, e
);
3244 /* Return true when BB has label LABEL in it. */
3247 has_label_p (basic_block bb
, tree label
)
3249 block_stmt_iterator bsi
;
3251 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
3253 tree stmt
= bsi_stmt (bsi
);
3255 if (TREE_CODE (stmt
) != LABEL_EXPR
)
3257 if (LABEL_EXPR_LABEL (stmt
) == label
)
3264 /* Callback for walk_tree, check that all elements with address taken are
3265 properly noticed as such. The DATA is an int* that is 1 if TP was seen
3266 inside a PHI node. */
3269 verify_expr (tree
*tp
, int *walk_subtrees
, void *data ATTRIBUTE_UNUSED
)
3272 bool in_phi
= (data
!= NULL
);
3277 /* Check operand N for being valid GIMPLE and give error MSG if not.
3278 We check for constants explicitly since they are not considered
3279 gimple invariants if they overflowed. */
3280 #define CHECK_OP(N, MSG) \
3281 do { if (!CONSTANT_CLASS_P (TREE_OPERAND (t, N)) \
3282 && !is_gimple_val (TREE_OPERAND (t, N))) \
3283 { error (MSG); return TREE_OPERAND (t, N); }} while (0)
3285 switch (TREE_CODE (t
))
3288 if (SSA_NAME_IN_FREE_LIST (t
))
3290 error ("SSA name in freelist but still referenced");
3296 x
= TREE_OPERAND (t
, 0);
3297 if (TREE_CODE (x
) == BIT_FIELD_REF
3298 && is_gimple_reg (TREE_OPERAND (x
, 0)))
3300 error ("GIMPLE register modified with BIT_FIELD_REF");
3306 /* ??? tree-ssa-alias.c may have overlooked dead PHI nodes, missing
3307 dead PHIs that take the address of something. But if the PHI
3308 result is dead, the fact that it takes the address of anything
3309 is irrelevant. Because we can not tell from here if a PHI result
3310 is dead, we just skip this check for PHIs altogether. This means
3311 we may be missing "valid" checks, but what can you do?
3312 This was PR19217. */
3316 /* Skip any references (they will be checked when we recurse down the
3317 tree) and ensure that any variable used as a prefix is marked
3319 for (x
= TREE_OPERAND (t
, 0);
3320 handled_component_p (x
);
3321 x
= TREE_OPERAND (x
, 0))
3324 if (TREE_CODE (x
) != VAR_DECL
&& TREE_CODE (x
) != PARM_DECL
)
3326 if (!TREE_ADDRESSABLE (x
))
3328 error ("address taken, but ADDRESSABLE bit not set");
3334 x
= COND_EXPR_COND (t
);
3335 if (TREE_CODE (TREE_TYPE (x
)) != BOOLEAN_TYPE
)
3337 error ("non-boolean used in condition");
3344 case FIX_TRUNC_EXPR
:
3346 case FIX_FLOOR_EXPR
:
3347 case FIX_ROUND_EXPR
:
3352 case NON_LVALUE_EXPR
:
3353 case TRUTH_NOT_EXPR
:
3354 CHECK_OP (0, "Invalid operand to unary operator");
3361 case ARRAY_RANGE_REF
:
3363 case VIEW_CONVERT_EXPR
:
3364 /* We have a nest of references. Verify that each of the operands
3365 that determine where to reference is either a constant or a variable,
3366 verify that the base is valid, and then show we've already checked
3368 while (handled_component_p (t
))
3370 if (TREE_CODE (t
) == COMPONENT_REF
&& TREE_OPERAND (t
, 2))
3371 CHECK_OP (2, "Invalid COMPONENT_REF offset operator");
3372 else if (TREE_CODE (t
) == ARRAY_REF
3373 || TREE_CODE (t
) == ARRAY_RANGE_REF
)
3375 CHECK_OP (1, "Invalid array index.");
3376 if (TREE_OPERAND (t
, 2))
3377 CHECK_OP (2, "Invalid array lower bound.");
3378 if (TREE_OPERAND (t
, 3))
3379 CHECK_OP (3, "Invalid array stride.");
3381 else if (TREE_CODE (t
) == BIT_FIELD_REF
)
3383 CHECK_OP (1, "Invalid operand to BIT_FIELD_REF");
3384 CHECK_OP (2, "Invalid operand to BIT_FIELD_REF");
3387 t
= TREE_OPERAND (t
, 0);
3390 if (!CONSTANT_CLASS_P (t
) && !is_gimple_lvalue (t
))
3392 error ("Invalid reference prefix.");
3404 case UNORDERED_EXPR
:
3415 case TRUNC_DIV_EXPR
:
3417 case FLOOR_DIV_EXPR
:
3418 case ROUND_DIV_EXPR
:
3419 case TRUNC_MOD_EXPR
:
3421 case FLOOR_MOD_EXPR
:
3422 case ROUND_MOD_EXPR
:
3424 case EXACT_DIV_EXPR
:
3434 CHECK_OP (0, "Invalid operand to binary operator");
3435 CHECK_OP (1, "Invalid operand to binary operator");
3447 /* Verify STMT, return true if STMT is not in GIMPLE form.
3448 TODO: Implement type checking. */
3451 verify_stmt (tree stmt
, bool last_in_block
)
3455 if (!is_gimple_stmt (stmt
))
3457 error ("Is not a valid GIMPLE statement.");
3461 addr
= walk_tree (&stmt
, verify_expr
, NULL
, NULL
);
3464 debug_generic_stmt (addr
);
3468 /* If the statement is marked as part of an EH region, then it is
3469 expected that the statement could throw. Verify that when we
3470 have optimizations that simplify statements such that we prove
3471 that they cannot throw, that we update other data structures
3473 if (lookup_stmt_eh_region (stmt
) >= 0)
3475 if (!tree_could_throw_p (stmt
))
3477 error ("Statement marked for throw, but doesn%'t.");
3480 if (!last_in_block
&& tree_can_throw_internal (stmt
))
3482 error ("Statement marked for throw in middle of block.");
3490 debug_generic_stmt (stmt
);
3495 /* Return true when the T can be shared. */
3498 tree_node_can_be_shared (tree t
)
3500 if (IS_TYPE_OR_DECL_P (t
)
3501 /* We check for constants explicitly since they are not considered
3502 gimple invariants if they overflowed. */
3503 || CONSTANT_CLASS_P (t
)
3504 || is_gimple_min_invariant (t
)
3505 || TREE_CODE (t
) == SSA_NAME
3506 || t
== error_mark_node
)
3509 if (TREE_CODE (t
) == CASE_LABEL_EXPR
)
3512 while (((TREE_CODE (t
) == ARRAY_REF
|| TREE_CODE (t
) == ARRAY_RANGE_REF
)
3513 /* We check for constants explicitly since they are not considered
3514 gimple invariants if they overflowed. */
3515 && (CONSTANT_CLASS_P (TREE_OPERAND (t
, 1))
3516 || is_gimple_min_invariant (TREE_OPERAND (t
, 1))))
3517 || (TREE_CODE (t
) == COMPONENT_REF
3518 || TREE_CODE (t
) == REALPART_EXPR
3519 || TREE_CODE (t
) == IMAGPART_EXPR
))
3520 t
= TREE_OPERAND (t
, 0);
3529 /* Called via walk_trees. Verify tree sharing. */
3532 verify_node_sharing (tree
* tp
, int *walk_subtrees
, void *data
)
3534 htab_t htab
= (htab_t
) data
;
3537 if (tree_node_can_be_shared (*tp
))
3539 *walk_subtrees
= false;
3543 slot
= htab_find_slot (htab
, *tp
, INSERT
);
3552 /* Verify the GIMPLE statement chain. */
3558 block_stmt_iterator bsi
;
3563 timevar_push (TV_TREE_STMT_VERIFY
);
3564 htab
= htab_create (37, htab_hash_pointer
, htab_eq_pointer
, NULL
);
3571 for (phi
= phi_nodes (bb
); phi
; phi
= PHI_CHAIN (phi
))
3573 int phi_num_args
= PHI_NUM_ARGS (phi
);
3575 for (i
= 0; i
< phi_num_args
; i
++)
3577 tree t
= PHI_ARG_DEF (phi
, i
);
3580 /* Addressable variables do have SSA_NAMEs but they
3581 are not considered gimple values. */
3582 if (TREE_CODE (t
) != SSA_NAME
3583 && TREE_CODE (t
) != FUNCTION_DECL
3584 && !is_gimple_val (t
))
3586 error ("PHI def is not a GIMPLE value");
3587 debug_generic_stmt (phi
);
3588 debug_generic_stmt (t
);
3592 addr
= walk_tree (&t
, verify_expr
, (void *) 1, NULL
);
3595 debug_generic_stmt (addr
);
3599 addr
= walk_tree (&t
, verify_node_sharing
, htab
, NULL
);
3602 error ("Incorrect sharing of tree nodes");
3603 debug_generic_stmt (phi
);
3604 debug_generic_stmt (addr
);
3610 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); )
3612 tree stmt
= bsi_stmt (bsi
);
3614 err
|= verify_stmt (stmt
, bsi_end_p (bsi
));
3615 addr
= walk_tree (&stmt
, verify_node_sharing
, htab
, NULL
);
3618 error ("Incorrect sharing of tree nodes");
3619 debug_generic_stmt (stmt
);
3620 debug_generic_stmt (addr
);
3627 internal_error ("verify_stmts failed.");
3630 timevar_pop (TV_TREE_STMT_VERIFY
);
3634 /* Verifies that the flow information is OK. */
3637 tree_verify_flow_info (void)
3641 block_stmt_iterator bsi
;
3646 if (ENTRY_BLOCK_PTR
->stmt_list
)
3648 error ("ENTRY_BLOCK has a statement list associated with it\n");
3652 if (EXIT_BLOCK_PTR
->stmt_list
)
3654 error ("EXIT_BLOCK has a statement list associated with it\n");
3658 FOR_EACH_EDGE (e
, ei
, EXIT_BLOCK_PTR
->preds
)
3659 if (e
->flags
& EDGE_FALLTHRU
)
3661 error ("Fallthru to exit from bb %d\n", e
->src
->index
);
3667 bool found_ctrl_stmt
= false;
3671 /* Skip labels on the start of basic block. */
3672 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
3674 tree prev_stmt
= stmt
;
3676 stmt
= bsi_stmt (bsi
);
3678 if (TREE_CODE (stmt
) != LABEL_EXPR
)
3681 if (prev_stmt
&& DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt
)))
3683 error ("Nonlocal label %s is not first "
3684 "in a sequence of labels in bb %d",
3685 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt
))),
3690 if (label_to_block (LABEL_EXPR_LABEL (stmt
)) != bb
)
3692 error ("Label %s to block does not match in bb %d\n",
3693 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt
))),
3698 if (decl_function_context (LABEL_EXPR_LABEL (stmt
))
3699 != current_function_decl
)
3701 error ("Label %s has incorrect context in bb %d\n",
3702 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt
))),
3708 /* Verify that body of basic block BB is free of control flow. */
3709 for (; !bsi_end_p (bsi
); bsi_next (&bsi
))
3711 tree stmt
= bsi_stmt (bsi
);
3713 if (found_ctrl_stmt
)
3715 error ("Control flow in the middle of basic block %d\n",
3720 if (stmt_ends_bb_p (stmt
))
3721 found_ctrl_stmt
= true;
3723 if (TREE_CODE (stmt
) == LABEL_EXPR
)
3725 error ("Label %s in the middle of basic block %d\n",
3726 IDENTIFIER_POINTER (DECL_NAME (stmt
)),
3731 bsi
= bsi_last (bb
);
3732 if (bsi_end_p (bsi
))
3735 stmt
= bsi_stmt (bsi
);
3737 if (is_ctrl_stmt (stmt
))
3739 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
3740 if (e
->flags
& EDGE_FALLTHRU
)
3742 error ("Fallthru edge after a control statement in bb %d \n",
3748 switch (TREE_CODE (stmt
))
3754 if (TREE_CODE (COND_EXPR_THEN (stmt
)) != GOTO_EXPR
3755 || TREE_CODE (COND_EXPR_ELSE (stmt
)) != GOTO_EXPR
)
3757 error ("Structured COND_EXPR at the end of bb %d\n", bb
->index
);
3761 extract_true_false_edges_from_block (bb
, &true_edge
, &false_edge
);
3763 if (!true_edge
|| !false_edge
3764 || !(true_edge
->flags
& EDGE_TRUE_VALUE
)
3765 || !(false_edge
->flags
& EDGE_FALSE_VALUE
)
3766 || (true_edge
->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
))
3767 || (false_edge
->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
))
3768 || EDGE_COUNT (bb
->succs
) >= 3)
3770 error ("Wrong outgoing edge flags at end of bb %d\n",
3775 if (!has_label_p (true_edge
->dest
,
3776 GOTO_DESTINATION (COND_EXPR_THEN (stmt
))))
3778 error ("%<then%> label does not match edge at end of bb %d\n",
3783 if (!has_label_p (false_edge
->dest
,
3784 GOTO_DESTINATION (COND_EXPR_ELSE (stmt
))))
3786 error ("%<else%> label does not match edge at end of bb %d\n",
3794 if (simple_goto_p (stmt
))
3796 error ("Explicit goto at end of bb %d\n", bb
->index
);
3801 /* FIXME. We should double check that the labels in the
3802 destination blocks have their address taken. */
3803 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
3804 if ((e
->flags
& (EDGE_FALLTHRU
| EDGE_TRUE_VALUE
3805 | EDGE_FALSE_VALUE
))
3806 || !(e
->flags
& EDGE_ABNORMAL
))
3808 error ("Wrong outgoing edge flags at end of bb %d\n",
3816 if (EDGE_COUNT (bb
->succs
) != 1
3817 || (EDGE_SUCC (bb
, 0)->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
3818 | EDGE_TRUE_VALUE
| EDGE_FALSE_VALUE
)))
3820 error ("Wrong outgoing edge flags at end of bb %d\n", bb
->index
);
3823 if (EDGE_SUCC (bb
, 0)->dest
!= EXIT_BLOCK_PTR
)
3825 error ("Return edge does not point to exit in bb %d\n",
3838 vec
= SWITCH_LABELS (stmt
);
3839 n
= TREE_VEC_LENGTH (vec
);
3841 /* Mark all the destination basic blocks. */
3842 for (i
= 0; i
< n
; ++i
)
3844 tree lab
= CASE_LABEL (TREE_VEC_ELT (vec
, i
));
3845 basic_block label_bb
= label_to_block (lab
);
3847 gcc_assert (!label_bb
->aux
|| label_bb
->aux
== (void *)1);
3848 label_bb
->aux
= (void *)1;
3851 /* Verify that the case labels are sorted. */
3852 prev
= TREE_VEC_ELT (vec
, 0);
3853 for (i
= 1; i
< n
- 1; ++i
)
3855 tree c
= TREE_VEC_ELT (vec
, i
);
3858 error ("Found default case not at end of case vector");
3862 if (! tree_int_cst_lt (CASE_LOW (prev
), CASE_LOW (c
)))
3864 error ("Case labels not sorted:\n ");
3865 print_generic_expr (stderr
, prev
, 0);
3866 fprintf (stderr
," is greater than ");
3867 print_generic_expr (stderr
, c
, 0);
3868 fprintf (stderr
," but comes before it.\n");
3873 if (CASE_LOW (TREE_VEC_ELT (vec
, n
- 1)))
3875 error ("No default case found at end of case vector");
3879 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
3883 error ("Extra outgoing edge %d->%d\n",
3884 bb
->index
, e
->dest
->index
);
3887 e
->dest
->aux
= (void *)2;
3888 if ((e
->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
3889 | EDGE_TRUE_VALUE
| EDGE_FALSE_VALUE
)))
3891 error ("Wrong outgoing edge flags at end of bb %d\n",
3897 /* Check that we have all of them. */
3898 for (i
= 0; i
< n
; ++i
)
3900 tree lab
= CASE_LABEL (TREE_VEC_ELT (vec
, i
));
3901 basic_block label_bb
= label_to_block (lab
);
3903 if (label_bb
->aux
!= (void *)2)
3905 error ("Missing edge %i->%i",
3906 bb
->index
, label_bb
->index
);
3911 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
3912 e
->dest
->aux
= (void *)0;
3919 if (dom_computed
[CDI_DOMINATORS
] >= DOM_NO_FAST_QUERY
)
3920 verify_dominators (CDI_DOMINATORS
);
3926 /* Updates phi nodes after creating a forwarder block joined
3927 by edge FALLTHRU. */
3930 tree_make_forwarder_block (edge fallthru
)
3934 basic_block dummy
, bb
;
3935 tree phi
, new_phi
, var
;
3937 dummy
= fallthru
->src
;
3938 bb
= fallthru
->dest
;
3940 if (EDGE_COUNT (bb
->preds
) == 1)
3943 /* If we redirected a branch we must create new phi nodes at the
3945 for (phi
= phi_nodes (dummy
); phi
; phi
= PHI_CHAIN (phi
))
3947 var
= PHI_RESULT (phi
);
3948 new_phi
= create_phi_node (var
, bb
);
3949 SSA_NAME_DEF_STMT (var
) = new_phi
;
3950 SET_PHI_RESULT (phi
, make_ssa_name (SSA_NAME_VAR (var
), phi
));
3951 add_phi_arg (new_phi
, PHI_RESULT (phi
), fallthru
);
3954 /* Ensure that the PHI node chain is in the same order. */
3955 set_phi_nodes (bb
, phi_reverse (phi_nodes (bb
)));
3957 /* Add the arguments we have stored on edges. */
3958 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
3963 flush_pending_stmts (e
);
3968 /* Return true if basic block BB does nothing except pass control
3969 flow to another block and that we can safely insert a label at
3970 the start of the successor block.
3972 As a precondition, we require that BB be not equal to
3976 tree_forwarder_block_p (basic_block bb
, bool phi_wanted
)
3978 block_stmt_iterator bsi
;
3980 /* BB must have a single outgoing edge. */
3981 if (EDGE_COUNT (bb
->succs
) != 1
3982 /* If PHI_WANTED is false, BB must not have any PHI nodes.
3983 Otherwise, BB must have PHI nodes. */
3984 || (phi_nodes (bb
) != NULL_TREE
) != phi_wanted
3985 /* BB may not be a predecessor of EXIT_BLOCK_PTR. */
3986 || EDGE_SUCC (bb
, 0)->dest
== EXIT_BLOCK_PTR
3987 /* Nor should this be an infinite loop. */
3988 || EDGE_SUCC (bb
, 0)->dest
== bb
3989 /* BB may not have an abnormal outgoing edge. */
3990 || (EDGE_SUCC (bb
, 0)->flags
& EDGE_ABNORMAL
))
3994 gcc_assert (bb
!= ENTRY_BLOCK_PTR
);
3997 /* Now walk through the statements backward. We can ignore labels,
3998 anything else means this is not a forwarder block. */
3999 for (bsi
= bsi_last (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
4001 tree stmt
= bsi_stmt (bsi
);
4003 switch (TREE_CODE (stmt
))
4006 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt
)))
4015 if (find_edge (ENTRY_BLOCK_PTR
, bb
))
4021 /* Return true if BB has at least one abnormal incoming edge. */
4024 has_abnormal_incoming_edge_p (basic_block bb
)
4029 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
4030 if (e
->flags
& EDGE_ABNORMAL
)
4036 /* Removes forwarder block BB. Returns false if this failed. If a new
4037 forwarder block is created due to redirection of edges, it is
4038 stored to worklist. */
4041 remove_forwarder_block (basic_block bb
, basic_block
**worklist
)
4043 edge succ
= EDGE_SUCC (bb
, 0), e
, s
;
4044 basic_block dest
= succ
->dest
;
4048 block_stmt_iterator bsi
, bsi_to
;
4049 bool seen_abnormal_edge
= false;
4051 /* We check for infinite loops already in tree_forwarder_block_p.
4052 However it may happen that the infinite loop is created
4053 afterwards due to removal of forwarders. */
4057 /* If the destination block consists of a nonlocal label, do not merge
4059 label
= first_stmt (dest
);
4061 && TREE_CODE (label
) == LABEL_EXPR
4062 && DECL_NONLOCAL (LABEL_EXPR_LABEL (label
)))
4065 /* If there is an abnormal edge to basic block BB, but not into
4066 dest, problems might occur during removal of the phi node at out
4067 of ssa due to overlapping live ranges of registers.
4069 If there is an abnormal edge in DEST, the problems would occur
4070 anyway since cleanup_dead_labels would then merge the labels for
4071 two different eh regions, and rest of exception handling code
4074 So if there is an abnormal edge to BB, proceed only if there is
4075 no abnormal edge to DEST and there are no phi nodes in DEST. */
4076 if (has_abnormal_incoming_edge_p (bb
))
4078 seen_abnormal_edge
= true;
4080 if (has_abnormal_incoming_edge_p (dest
)
4081 || phi_nodes (dest
) != NULL_TREE
)
4085 /* If there are phi nodes in DEST, and some of the blocks that are
4086 predecessors of BB are also predecessors of DEST, check that the
4087 phi node arguments match. */
4088 if (phi_nodes (dest
))
4090 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
4092 s
= find_edge (e
->src
, dest
);
4096 if (!phi_alternatives_equal (dest
, succ
, s
))
4101 /* Redirect the edges. */
4102 for (ei
= ei_start (bb
->preds
); (e
= ei_safe_edge (ei
)); )
4104 if (e
->flags
& EDGE_ABNORMAL
)
4106 /* If there is an abnormal edge, redirect it anyway, and
4107 move the labels to the new block to make it legal. */
4108 s
= redirect_edge_succ_nodup (e
, dest
);
4111 s
= redirect_edge_and_branch (e
, dest
);
4115 /* Create arguments for the phi nodes, since the edge was not
4117 for (phi
= phi_nodes (dest
); phi
; phi
= PHI_CHAIN (phi
))
4118 add_phi_arg (phi
, PHI_ARG_DEF (phi
, succ
->dest_idx
), s
);
4122 /* The source basic block might become a forwarder. We know
4123 that it was not a forwarder before, since it used to have
4124 at least two outgoing edges, so we may just add it to
4126 if (tree_forwarder_block_p (s
->src
, false))
4127 *(*worklist
)++ = s
->src
;
4131 if (seen_abnormal_edge
)
4133 /* Move the labels to the new block, so that the redirection of
4134 the abnormal edges works. */
4136 bsi_to
= bsi_start (dest
);
4137 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); )
4139 label
= bsi_stmt (bsi
);
4140 gcc_assert (TREE_CODE (label
) == LABEL_EXPR
);
4142 bsi_insert_before (&bsi_to
, label
, BSI_CONTINUE_LINKING
);
4146 /* Update the dominators. */
4147 if (dom_info_available_p (CDI_DOMINATORS
))
4149 basic_block dom
, dombb
, domdest
;
4151 dombb
= get_immediate_dominator (CDI_DOMINATORS
, bb
);
4152 domdest
= get_immediate_dominator (CDI_DOMINATORS
, dest
);
4155 /* Shortcut to avoid calling (relatively expensive)
4156 nearest_common_dominator unless necessary. */
4160 dom
= nearest_common_dominator (CDI_DOMINATORS
, domdest
, dombb
);
4162 set_immediate_dominator (CDI_DOMINATORS
, dest
, dom
);
4165 /* And kill the forwarder block. */
4166 delete_basic_block (bb
);
4171 /* Removes forwarder blocks. */
4174 cleanup_forwarder_blocks (void)
4177 bool changed
= false;
4178 basic_block
*worklist
= xmalloc (sizeof (basic_block
) * n_basic_blocks
);
4179 basic_block
*current
= worklist
;
4183 if (tree_forwarder_block_p (bb
, false))
4187 while (current
!= worklist
)
4190 changed
|= remove_forwarder_block (bb
, ¤t
);
4197 /* Merge the PHI nodes at BB into those at BB's sole successor. */
4200 remove_forwarder_block_with_phi (basic_block bb
)
4202 edge succ
= EDGE_SUCC (bb
, 0);
4203 basic_block dest
= succ
->dest
;
4205 basic_block dombb
, domdest
, dom
;
4207 /* We check for infinite loops already in tree_forwarder_block_p.
4208 However it may happen that the infinite loop is created
4209 afterwards due to removal of forwarders. */
4213 /* If the destination block consists of a nonlocal label, do not
4215 label
= first_stmt (dest
);
4217 && TREE_CODE (label
) == LABEL_EXPR
4218 && DECL_NONLOCAL (LABEL_EXPR_LABEL (label
)))
4221 /* Redirect each incoming edge to BB to DEST. */
4222 while (EDGE_COUNT (bb
->preds
) > 0)
4224 edge e
= EDGE_PRED (bb
, 0), s
;
4227 s
= find_edge (e
->src
, dest
);
4230 /* We already have an edge S from E->src to DEST. If S and
4231 E->dest's sole successor edge have the same PHI arguments
4232 at DEST, redirect S to DEST. */
4233 if (phi_alternatives_equal (dest
, s
, succ
))
4235 e
= redirect_edge_and_branch (e
, dest
);
4236 PENDING_STMT (e
) = NULL_TREE
;
4240 /* PHI arguments are different. Create a forwarder block by
4241 splitting E so that we can merge PHI arguments on E to
4243 e
= EDGE_SUCC (split_edge (e
), 0);
4246 s
= redirect_edge_and_branch (e
, dest
);
4248 /* redirect_edge_and_branch must not create a new edge. */
4249 gcc_assert (s
== e
);
4251 /* Add to the PHI nodes at DEST each PHI argument removed at the
4252 destination of E. */
4253 for (phi
= phi_nodes (dest
); phi
; phi
= PHI_CHAIN (phi
))
4255 tree def
= PHI_ARG_DEF (phi
, succ
->dest_idx
);
4257 if (TREE_CODE (def
) == SSA_NAME
)
4261 /* If DEF is one of the results of PHI nodes removed during
4262 redirection, replace it with the PHI argument that used
4264 for (var
= PENDING_STMT (e
); var
; var
= TREE_CHAIN (var
))
4266 tree old_arg
= TREE_PURPOSE (var
);
4267 tree new_arg
= TREE_VALUE (var
);
4277 add_phi_arg (phi
, def
, s
);
4280 PENDING_STMT (e
) = NULL
;
4283 /* Update the dominators. */
4284 dombb
= get_immediate_dominator (CDI_DOMINATORS
, bb
);
4285 domdest
= get_immediate_dominator (CDI_DOMINATORS
, dest
);
4288 /* Shortcut to avoid calling (relatively expensive)
4289 nearest_common_dominator unless necessary. */
4293 dom
= nearest_common_dominator (CDI_DOMINATORS
, domdest
, dombb
);
4295 set_immediate_dominator (CDI_DOMINATORS
, dest
, dom
);
4297 /* Remove BB since all of BB's incoming edges have been redirected
4299 delete_basic_block (bb
);
4302 /* This pass merges PHI nodes if one feeds into another. For example,
4303 suppose we have the following:
4310 # tem_6 = PHI <tem_17(8), tem_23(7)>;
4313 # tem_3 = PHI <tem_6(9), tem_2(5)>;
4316 Then we merge the first PHI node into the second one like so:
4318 goto <bb 9> (<L10>);
4323 # tem_3 = PHI <tem_23(7), tem_2(5), tem_17(8)>;
4328 merge_phi_nodes (void)
4330 basic_block
*worklist
= xmalloc (sizeof (basic_block
) * n_basic_blocks
);
4331 basic_block
*current
= worklist
;
4334 calculate_dominance_info (CDI_DOMINATORS
);
4336 /* Find all PHI nodes that we may be able to merge. */
4341 /* Look for a forwarder block with PHI nodes. */
4342 if (!tree_forwarder_block_p (bb
, true))
4345 dest
= EDGE_SUCC (bb
, 0)->dest
;
4347 /* We have to feed into another basic block with PHI
4349 if (!phi_nodes (dest
)
4350 /* We don't want to deal with a basic block with
4352 || has_abnormal_incoming_edge_p (bb
))
4355 if (!dominated_by_p (CDI_DOMINATORS
, dest
, bb
))
4357 /* If BB does not dominate DEST, then the PHI nodes at
4358 DEST must be the only users of the results of the PHI
4364 /* Now let's drain WORKLIST. */
4365 while (current
!= worklist
)
4368 remove_forwarder_block_with_phi (bb
);
4375 gate_merge_phi (void)
4380 struct tree_opt_pass pass_merge_phi
= {
4381 "mergephi", /* name */
4382 gate_merge_phi
, /* gate */
4383 merge_phi_nodes
, /* execute */
4386 0, /* static_pass_number */
4387 TV_TREE_MERGE_PHI
, /* tv_id */
4388 PROP_cfg
| PROP_ssa
, /* properties_required */
4389 0, /* properties_provided */
4390 0, /* properties_destroyed */
4391 0, /* todo_flags_start */
4392 TODO_dump_func
| TODO_ggc_collect
/* todo_flags_finish */
4397 /* Return a non-special label in the head of basic block BLOCK.
4398 Create one if it doesn't exist. */
4401 tree_block_label (basic_block bb
)
4403 block_stmt_iterator i
, s
= bsi_start (bb
);
4407 for (i
= s
; !bsi_end_p (i
); first
= false, bsi_next (&i
))
4409 stmt
= bsi_stmt (i
);
4410 if (TREE_CODE (stmt
) != LABEL_EXPR
)
4412 label
= LABEL_EXPR_LABEL (stmt
);
4413 if (!DECL_NONLOCAL (label
))
4416 bsi_move_before (&i
, &s
);
4421 label
= create_artificial_label ();
4422 stmt
= build1 (LABEL_EXPR
, void_type_node
, label
);
4423 bsi_insert_before (&s
, stmt
, BSI_NEW_STMT
);
4428 /* Attempt to perform edge redirection by replacing a possibly complex
4429 jump instruction by a goto or by removing the jump completely.
4430 This can apply only if all edges now point to the same block. The
4431 parameters and return values are equivalent to
4432 redirect_edge_and_branch. */
4435 tree_try_redirect_by_replacing_jump (edge e
, basic_block target
)
4437 basic_block src
= e
->src
;
4438 block_stmt_iterator b
;
4441 /* We can replace or remove a complex jump only when we have exactly
4443 if (EDGE_COUNT (src
->succs
) != 2
4444 /* Verify that all targets will be TARGET. Specifically, the
4445 edge that is not E must also go to TARGET. */
4446 || EDGE_SUCC (src
, EDGE_SUCC (src
, 0) == e
)->dest
!= target
)
4452 stmt
= bsi_stmt (b
);
4454 if (TREE_CODE (stmt
) == COND_EXPR
4455 || TREE_CODE (stmt
) == SWITCH_EXPR
)
4458 e
= ssa_redirect_edge (e
, target
);
4459 e
->flags
= EDGE_FALLTHRU
;
4467 /* Redirect E to DEST. Return NULL on failure. Otherwise, return the
4468 edge representing the redirected branch. */
4471 tree_redirect_edge_and_branch (edge e
, basic_block dest
)
4473 basic_block bb
= e
->src
;
4474 block_stmt_iterator bsi
;
4478 if (e
->flags
& (EDGE_ABNORMAL_CALL
| EDGE_EH
))
4481 if (e
->src
!= ENTRY_BLOCK_PTR
4482 && (ret
= tree_try_redirect_by_replacing_jump (e
, dest
)))
4485 if (e
->dest
== dest
)
4488 label
= tree_block_label (dest
);
4490 bsi
= bsi_last (bb
);
4491 stmt
= bsi_end_p (bsi
) ? NULL
: bsi_stmt (bsi
);
4493 switch (stmt
? TREE_CODE (stmt
) : ERROR_MARK
)
4496 stmt
= (e
->flags
& EDGE_TRUE_VALUE
4497 ? COND_EXPR_THEN (stmt
)
4498 : COND_EXPR_ELSE (stmt
));
4499 GOTO_DESTINATION (stmt
) = label
;
4503 /* No non-abnormal edges should lead from a non-simple goto, and
4504 simple ones should be represented implicitly. */
4509 tree cases
= get_cases_for_edge (e
, stmt
);
4511 /* If we have a list of cases associated with E, then use it
4512 as it's a lot faster than walking the entire case vector. */
4515 edge e2
= find_edge (e
->src
, dest
);
4522 CASE_LABEL (cases
) = label
;
4523 cases
= TREE_CHAIN (cases
);
4526 /* If there was already an edge in the CFG, then we need
4527 to move all the cases associated with E to E2. */
4530 tree cases2
= get_cases_for_edge (e2
, stmt
);
4532 TREE_CHAIN (last
) = TREE_CHAIN (cases2
);
4533 TREE_CHAIN (cases2
) = first
;
4538 tree vec
= SWITCH_LABELS (stmt
);
4539 size_t i
, n
= TREE_VEC_LENGTH (vec
);
4541 for (i
= 0; i
< n
; i
++)
4543 tree elt
= TREE_VEC_ELT (vec
, i
);
4545 if (label_to_block (CASE_LABEL (elt
)) == e
->dest
)
4546 CASE_LABEL (elt
) = label
;
4555 e
->flags
|= EDGE_FALLTHRU
;
4559 /* Otherwise it must be a fallthru edge, and we don't need to
4560 do anything besides redirecting it. */
4561 gcc_assert (e
->flags
& EDGE_FALLTHRU
);
4565 /* Update/insert PHI nodes as necessary. */
4567 /* Now update the edges in the CFG. */
4568 e
= ssa_redirect_edge (e
, dest
);
4574 /* Simple wrapper, as we can always redirect fallthru edges. */
4577 tree_redirect_edge_and_branch_force (edge e
, basic_block dest
)
4579 e
= tree_redirect_edge_and_branch (e
, dest
);
4586 /* Splits basic block BB after statement STMT (but at least after the
4587 labels). If STMT is NULL, BB is split just after the labels. */
4590 tree_split_block (basic_block bb
, void *stmt
)
4592 block_stmt_iterator bsi
, bsi_tgt
;
4598 new_bb
= create_empty_bb (bb
);
4600 /* Redirect the outgoing edges. */
4601 new_bb
->succs
= bb
->succs
;
4603 FOR_EACH_EDGE (e
, ei
, new_bb
->succs
)
4606 if (stmt
&& TREE_CODE ((tree
) stmt
) == LABEL_EXPR
)
4609 /* Move everything from BSI to the new basic block. */
4610 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
4612 act
= bsi_stmt (bsi
);
4613 if (TREE_CODE (act
) == LABEL_EXPR
)
4626 bsi_tgt
= bsi_start (new_bb
);
4627 while (!bsi_end_p (bsi
))
4629 act
= bsi_stmt (bsi
);
4631 bsi_insert_after (&bsi_tgt
, act
, BSI_NEW_STMT
);
4638 /* Moves basic block BB after block AFTER. */
4641 tree_move_block_after (basic_block bb
, basic_block after
)
4643 if (bb
->prev_bb
== after
)
4647 link_block (bb
, after
);
4653 /* Return true if basic_block can be duplicated. */
4656 tree_can_duplicate_bb_p (basic_block bb ATTRIBUTE_UNUSED
)
4661 /* Create a duplicate of the basic block BB. NOTE: This does not
4662 preserve SSA form. */
4665 tree_duplicate_bb (basic_block bb
)
4668 block_stmt_iterator bsi
, bsi_tgt
;
4670 ssa_op_iter op_iter
;
4672 new_bb
= create_empty_bb (EXIT_BLOCK_PTR
->prev_bb
);
4674 /* First copy the phi nodes. We do not copy phi node arguments here,
4675 since the edges are not ready yet. Keep the chain of phi nodes in
4676 the same order, so that we can add them later. */
4677 for (phi
= phi_nodes (bb
); phi
; phi
= PHI_CHAIN (phi
))
4679 mark_for_rewrite (PHI_RESULT (phi
));
4680 create_phi_node (PHI_RESULT (phi
), new_bb
);
4682 set_phi_nodes (new_bb
, phi_reverse (phi_nodes (new_bb
)));
4684 bsi_tgt
= bsi_start (new_bb
);
4685 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
4687 tree stmt
= bsi_stmt (bsi
);
4690 if (TREE_CODE (stmt
) == LABEL_EXPR
)
4693 /* Record the definitions. */
4694 get_stmt_operands (stmt
);
4696 FOR_EACH_SSA_TREE_OPERAND (val
, stmt
, op_iter
, SSA_OP_ALL_DEFS
)
4697 mark_for_rewrite (val
);
4699 copy
= unshare_expr (stmt
);
4701 /* Copy also the virtual operands. */
4702 get_stmt_ann (copy
);
4703 copy_virtual_operands (copy
, stmt
);
4705 bsi_insert_after (&bsi_tgt
, copy
, BSI_NEW_STMT
);
4711 /* Basic block BB_COPY was created by code duplication. Add phi node
4712 arguments for edges going out of BB_COPY. The blocks that were
4713 duplicated have rbi->duplicated set to one. */
4716 add_phi_args_after_copy_bb (basic_block bb_copy
)
4718 basic_block bb
, dest
;
4721 tree phi
, phi_copy
, phi_next
, def
;
4723 bb
= bb_copy
->rbi
->original
;
4725 FOR_EACH_EDGE (e_copy
, ei
, bb_copy
->succs
)
4727 if (!phi_nodes (e_copy
->dest
))
4730 if (e_copy
->dest
->rbi
->duplicated
)
4731 dest
= e_copy
->dest
->rbi
->original
;
4733 dest
= e_copy
->dest
;
4735 e
= find_edge (bb
, dest
);
4738 /* During loop unrolling the target of the latch edge is copied.
4739 In this case we are not looking for edge to dest, but to
4740 duplicated block whose original was dest. */
4741 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
4742 if (e
->dest
->rbi
->duplicated
4743 && e
->dest
->rbi
->original
== dest
)
4746 gcc_assert (e
!= NULL
);
4749 for (phi
= phi_nodes (e
->dest
), phi_copy
= phi_nodes (e_copy
->dest
);
4751 phi
= phi_next
, phi_copy
= PHI_CHAIN (phi_copy
))
4753 phi_next
= PHI_CHAIN (phi
);
4755 gcc_assert (PHI_RESULT (phi
) == PHI_RESULT (phi_copy
));
4756 def
= PHI_ARG_DEF_FROM_EDGE (phi
, e
);
4757 add_phi_arg (phi_copy
, def
, e_copy
);
4762 /* Blocks in REGION_COPY array of length N_REGION were created by
4763 duplication of basic blocks. Add phi node arguments for edges
4764 going from these blocks. */
4767 add_phi_args_after_copy (basic_block
*region_copy
, unsigned n_region
)
4771 for (i
= 0; i
< n_region
; i
++)
4772 region_copy
[i
]->rbi
->duplicated
= 1;
4774 for (i
= 0; i
< n_region
; i
++)
4775 add_phi_args_after_copy_bb (region_copy
[i
]);
4777 for (i
= 0; i
< n_region
; i
++)
4778 region_copy
[i
]->rbi
->duplicated
= 0;
4781 /* Maps the old ssa name FROM_NAME to TO_NAME. */
4783 struct ssa_name_map_entry
4789 /* Hash function for ssa_name_map_entry. */
4792 ssa_name_map_entry_hash (const void *entry
)
4794 const struct ssa_name_map_entry
*en
= entry
;
4795 return SSA_NAME_VERSION (en
->from_name
);
4798 /* Equality function for ssa_name_map_entry. */
4801 ssa_name_map_entry_eq (const void *in_table
, const void *ssa_name
)
4803 const struct ssa_name_map_entry
*en
= in_table
;
4805 return en
->from_name
== ssa_name
;
4808 /* Allocate duplicates of ssa names in list DEFINITIONS and store the mapping
4812 allocate_ssa_names (bitmap definitions
, htab_t
*map
)
4815 struct ssa_name_map_entry
*entry
;
4821 *map
= htab_create (10, ssa_name_map_entry_hash
,
4822 ssa_name_map_entry_eq
, free
);
4823 EXECUTE_IF_SET_IN_BITMAP (definitions
, 0, ver
, bi
)
4825 name
= ssa_name (ver
);
4826 slot
= htab_find_slot_with_hash (*map
, name
, SSA_NAME_VERSION (name
),
4832 entry
= xmalloc (sizeof (struct ssa_name_map_entry
));
4833 entry
->from_name
= name
;
4836 entry
->to_name
= duplicate_ssa_name (name
, SSA_NAME_DEF_STMT (name
));
4840 /* Rewrite the definition DEF in statement STMT to new ssa name as specified
4841 by the mapping MAP. */
4844 rewrite_to_new_ssa_names_def (def_operand_p def
, tree stmt
, htab_t map
)
4846 tree name
= DEF_FROM_PTR (def
);
4847 struct ssa_name_map_entry
*entry
;
4849 gcc_assert (TREE_CODE (name
) == SSA_NAME
);
4851 entry
= htab_find_with_hash (map
, name
, SSA_NAME_VERSION (name
));
4855 SET_DEF (def
, entry
->to_name
);
4856 SSA_NAME_DEF_STMT (entry
->to_name
) = stmt
;
4859 /* Rewrite the USE to new ssa name as specified by the mapping MAP. */
4862 rewrite_to_new_ssa_names_use (use_operand_p use
, htab_t map
)
4864 tree name
= USE_FROM_PTR (use
);
4865 struct ssa_name_map_entry
*entry
;
4867 if (TREE_CODE (name
) != SSA_NAME
)
4870 entry
= htab_find_with_hash (map
, name
, SSA_NAME_VERSION (name
));
4874 SET_USE (use
, entry
->to_name
);
4877 /* Rewrite the ssa names in basic block BB to new ones as specified by the
4881 rewrite_to_new_ssa_names_bb (basic_block bb
, htab_t map
)
4887 block_stmt_iterator bsi
;
4891 v_may_def_optype v_may_defs
;
4892 v_must_def_optype v_must_defs
;
4895 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
4896 if (e
->flags
& EDGE_ABNORMAL
)
4899 for (phi
= phi_nodes (bb
); phi
; phi
= PHI_CHAIN (phi
))
4901 rewrite_to_new_ssa_names_def (PHI_RESULT_PTR (phi
), phi
, map
);
4903 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (PHI_RESULT (phi
)) = 1;
4906 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
4908 stmt
= bsi_stmt (bsi
);
4909 get_stmt_operands (stmt
);
4910 ann
= stmt_ann (stmt
);
4912 uses
= USE_OPS (ann
);
4913 for (i
= 0; i
< NUM_USES (uses
); i
++)
4914 rewrite_to_new_ssa_names_use (USE_OP_PTR (uses
, i
), map
);
4916 defs
= DEF_OPS (ann
);
4917 for (i
= 0; i
< NUM_DEFS (defs
); i
++)
4918 rewrite_to_new_ssa_names_def (DEF_OP_PTR (defs
, i
), stmt
, map
);
4920 vuses
= VUSE_OPS (ann
);
4921 for (i
= 0; i
< NUM_VUSES (vuses
); i
++)
4922 rewrite_to_new_ssa_names_use (VUSE_OP_PTR (vuses
, i
), map
);
4924 v_may_defs
= V_MAY_DEF_OPS (ann
);
4925 for (i
= 0; i
< NUM_V_MAY_DEFS (v_may_defs
); i
++)
4927 rewrite_to_new_ssa_names_use
4928 (V_MAY_DEF_OP_PTR (v_may_defs
, i
), map
);
4929 rewrite_to_new_ssa_names_def
4930 (V_MAY_DEF_RESULT_PTR (v_may_defs
, i
), stmt
, map
);
4933 v_must_defs
= V_MUST_DEF_OPS (ann
);
4934 for (i
= 0; i
< NUM_V_MUST_DEFS (v_must_defs
); i
++)
4936 rewrite_to_new_ssa_names_def
4937 (V_MUST_DEF_RESULT_PTR (v_must_defs
, i
), stmt
, map
);
4938 rewrite_to_new_ssa_names_use
4939 (V_MUST_DEF_KILL_PTR (v_must_defs
, i
), map
);
4943 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
4944 for (phi
= phi_nodes (e
->dest
); phi
; phi
= PHI_CHAIN (phi
))
4946 rewrite_to_new_ssa_names_use
4947 (PHI_ARG_DEF_PTR_FROM_EDGE (phi
, e
), map
);
4949 if (e
->flags
& EDGE_ABNORMAL
)
4951 tree op
= PHI_ARG_DEF_FROM_EDGE (phi
, e
);
4952 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op
) = 1;
4957 /* Rewrite the ssa names in N_REGION blocks REGION to the new ones as specified
4958 by the mapping MAP. */
4961 rewrite_to_new_ssa_names (basic_block
*region
, unsigned n_region
, htab_t map
)
4965 for (r
= 0; r
< n_region
; r
++)
4966 rewrite_to_new_ssa_names_bb (region
[r
], map
);
4969 /* Duplicates a REGION (set of N_REGION basic blocks) with just a single
4970 important exit edge EXIT. By important we mean that no SSA name defined
4971 inside region is live over the other exit edges of the region. All entry
4972 edges to the region must go to ENTRY->dest. The edge ENTRY is redirected
4973 to the duplicate of the region. SSA form, dominance and loop information
4974 is updated. The new basic blocks are stored to REGION_COPY in the same
4975 order as they had in REGION, provided that REGION_COPY is not NULL.
4976 The function returns false if it is unable to copy the region,
4980 tree_duplicate_sese_region (edge entry
, edge exit
,
4981 basic_block
*region
, unsigned n_region
,
4982 basic_block
*region_copy
)
4984 unsigned i
, n_doms
, ver
;
4985 bool free_region_copy
= false, copying_header
= false;
4986 struct loop
*loop
= entry
->dest
->loop_father
;
4991 htab_t ssa_name_map
= NULL
;
4995 if (!can_copy_bbs_p (region
, n_region
))
4998 /* Some sanity checking. Note that we do not check for all possible
4999 missuses of the functions. I.e. if you ask to copy something weird,
5000 it will work, but the state of structures probably will not be
5003 for (i
= 0; i
< n_region
; i
++)
5005 /* We do not handle subloops, i.e. all the blocks must belong to the
5007 if (region
[i
]->loop_father
!= loop
)
5010 if (region
[i
] != entry
->dest
5011 && region
[i
] == loop
->header
)
5017 /* In case the function is used for loop header copying (which is the primary
5018 use), ensure that EXIT and its copy will be new latch and entry edges. */
5019 if (loop
->header
== entry
->dest
)
5021 copying_header
= true;
5022 loop
->copy
= loop
->outer
;
5024 if (!dominated_by_p (CDI_DOMINATORS
, loop
->latch
, exit
->src
))
5027 for (i
= 0; i
< n_region
; i
++)
5028 if (region
[i
] != exit
->src
5029 && dominated_by_p (CDI_DOMINATORS
, region
[i
], exit
->src
))
5035 region_copy
= xmalloc (sizeof (basic_block
) * n_region
);
5036 free_region_copy
= true;
5039 gcc_assert (!any_marked_for_rewrite_p ());
5041 /* Record blocks outside the region that are duplicated by something
5043 doms
= xmalloc (sizeof (basic_block
) * n_basic_blocks
);
5044 n_doms
= get_dominated_by_region (CDI_DOMINATORS
, region
, n_region
, doms
);
5046 copy_bbs (region
, n_region
, region_copy
, &exit
, 1, &exit_copy
, loop
);
5047 definitions
= marked_ssa_names ();
5051 loop
->header
= exit
->dest
;
5052 loop
->latch
= exit
->src
;
5055 /* Redirect the entry and add the phi node arguments. */
5056 redirected
= redirect_edge_and_branch (entry
, entry
->dest
->rbi
->copy
);
5057 gcc_assert (redirected
!= NULL
);
5058 flush_pending_stmts (entry
);
5060 /* Concerning updating of dominators: We must recount dominators
5061 for entry block and its copy. Anything that is outside of the region, but
5062 was dominated by something inside needs recounting as well. */
5063 set_immediate_dominator (CDI_DOMINATORS
, entry
->dest
, entry
->src
);
5064 doms
[n_doms
++] = entry
->dest
->rbi
->original
;
5065 iterate_fix_dominators (CDI_DOMINATORS
, doms
, n_doms
);
5068 /* Add the other phi node arguments. */
5069 add_phi_args_after_copy (region_copy
, n_region
);
5071 /* Add phi nodes for definitions at exit. TODO -- once we have immediate
5072 uses, it should be possible to emit phi nodes just for definitions that
5073 are used outside region. */
5074 EXECUTE_IF_SET_IN_BITMAP (definitions
, 0, ver
, bi
)
5076 tree name
= ssa_name (ver
);
5078 phi
= create_phi_node (name
, exit
->dest
);
5079 add_phi_arg (phi
, name
, exit
);
5080 add_phi_arg (phi
, name
, exit_copy
);
5082 SSA_NAME_DEF_STMT (name
) = phi
;
5085 /* And create new definitions inside region and its copy. TODO -- once we
5086 have immediate uses, it might be better to leave definitions in region
5087 unchanged, create new ssa names for phi nodes on exit, and rewrite
5088 the uses, to avoid changing the copied region. */
5089 allocate_ssa_names (definitions
, &ssa_name_map
);
5090 rewrite_to_new_ssa_names (region
, n_region
, ssa_name_map
);
5091 allocate_ssa_names (definitions
, &ssa_name_map
);
5092 rewrite_to_new_ssa_names (region_copy
, n_region
, ssa_name_map
);
5093 htab_delete (ssa_name_map
);
5095 if (free_region_copy
)
5098 unmark_all_for_rewrite ();
5099 BITMAP_FREE (definitions
);
5104 /* Dump FUNCTION_DECL FN to file FILE using FLAGS (see TDF_* in tree.h) */
5107 dump_function_to_file (tree fn
, FILE *file
, int flags
)
5109 tree arg
, vars
, var
;
5110 bool ignore_topmost_bind
= false, any_var
= false;
5114 fprintf (file
, "%s (", lang_hooks
.decl_printable_name (fn
, 2));
5116 arg
= DECL_ARGUMENTS (fn
);
5119 print_generic_expr (file
, arg
, dump_flags
);
5120 if (TREE_CHAIN (arg
))
5121 fprintf (file
, ", ");
5122 arg
= TREE_CHAIN (arg
);
5124 fprintf (file
, ")\n");
5126 if (flags
& TDF_RAW
)
5128 dump_node (fn
, TDF_SLIM
| flags
, file
);
5132 /* When GIMPLE is lowered, the variables are no longer available in
5133 BIND_EXPRs, so display them separately. */
5134 if (cfun
&& cfun
->unexpanded_var_list
)
5136 ignore_topmost_bind
= true;
5138 fprintf (file
, "{\n");
5139 for (vars
= cfun
->unexpanded_var_list
; vars
; vars
= TREE_CHAIN (vars
))
5141 var
= TREE_VALUE (vars
);
5143 print_generic_decl (file
, var
, flags
);
5144 fprintf (file
, "\n");
5150 if (basic_block_info
)
5152 /* Make a CFG based dump. */
5153 check_bb_profile (ENTRY_BLOCK_PTR
, file
);
5154 if (!ignore_topmost_bind
)
5155 fprintf (file
, "{\n");
5157 if (any_var
&& n_basic_blocks
)
5158 fprintf (file
, "\n");
5161 dump_generic_bb (file
, bb
, 2, flags
);
5163 fprintf (file
, "}\n");
5164 check_bb_profile (EXIT_BLOCK_PTR
, file
);
5170 /* Make a tree based dump. */
5171 chain
= DECL_SAVED_TREE (fn
);
5173 if (TREE_CODE (chain
) == BIND_EXPR
)
5175 if (ignore_topmost_bind
)
5177 chain
= BIND_EXPR_BODY (chain
);
5185 if (!ignore_topmost_bind
)
5186 fprintf (file
, "{\n");
5191 fprintf (file
, "\n");
5193 print_generic_stmt_indented (file
, chain
, flags
, indent
);
5194 if (ignore_topmost_bind
)
5195 fprintf (file
, "}\n");
5198 fprintf (file
, "\n\n");
5202 /* Pretty print of the loops intermediate representation. */
5203 static void print_loop (FILE *, struct loop
*, int);
5204 static void print_pred_bbs (FILE *, basic_block bb
);
5205 static void print_succ_bbs (FILE *, basic_block bb
);
5208 /* Print the predecessors indexes of edge E on FILE. */
5211 print_pred_bbs (FILE *file
, basic_block bb
)
5216 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
5217 fprintf (file
, "bb_%d", e
->src
->index
);
5221 /* Print the successors indexes of edge E on FILE. */
5224 print_succ_bbs (FILE *file
, basic_block bb
)
5229 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
5230 fprintf (file
, "bb_%d", e
->src
->index
);
5234 /* Pretty print LOOP on FILE, indented INDENT spaces. */
5237 print_loop (FILE *file
, struct loop
*loop
, int indent
)
5245 s_indent
= (char *) alloca ((size_t) indent
+ 1);
5246 memset ((void *) s_indent
, ' ', (size_t) indent
);
5247 s_indent
[indent
] = '\0';
5249 /* Print the loop's header. */
5250 fprintf (file
, "%sloop_%d\n", s_indent
, loop
->num
);
5252 /* Print the loop's body. */
5253 fprintf (file
, "%s{\n", s_indent
);
5255 if (bb
->loop_father
== loop
)
5257 /* Print the basic_block's header. */
5258 fprintf (file
, "%s bb_%d (preds = {", s_indent
, bb
->index
);
5259 print_pred_bbs (file
, bb
);
5260 fprintf (file
, "}, succs = {");
5261 print_succ_bbs (file
, bb
);
5262 fprintf (file
, "})\n");
5264 /* Print the basic_block's body. */
5265 fprintf (file
, "%s {\n", s_indent
);
5266 tree_dump_bb (bb
, file
, indent
+ 4);
5267 fprintf (file
, "%s }\n", s_indent
);
5270 print_loop (file
, loop
->inner
, indent
+ 2);
5271 fprintf (file
, "%s}\n", s_indent
);
5272 print_loop (file
, loop
->next
, indent
);
5276 /* Follow a CFG edge from the entry point of the program, and on entry
5277 of a loop, pretty print the loop structure on FILE. */
5280 print_loop_ir (FILE *file
)
5284 bb
= BASIC_BLOCK (0);
5285 if (bb
&& bb
->loop_father
)
5286 print_loop (file
, bb
->loop_father
, 0);
5290 /* Debugging loops structure at tree level. */
5293 debug_loop_ir (void)
5295 print_loop_ir (stderr
);
5299 /* Return true if BB ends with a call, possibly followed by some
5300 instructions that must stay with the call. Return false,
5304 tree_block_ends_with_call_p (basic_block bb
)
5306 block_stmt_iterator bsi
= bsi_last (bb
);
5307 return get_call_expr_in (bsi_stmt (bsi
)) != NULL
;
5311 /* Return true if BB ends with a conditional branch. Return false,
5315 tree_block_ends_with_condjump_p (basic_block bb
)
5317 tree stmt
= tsi_stmt (bsi_last (bb
).tsi
);
5318 return (TREE_CODE (stmt
) == COND_EXPR
);
5322 /* Return true if we need to add fake edge to exit at statement T.
5323 Helper function for tree_flow_call_edges_add. */
5326 need_fake_edge_p (tree t
)
5330 /* NORETURN and LONGJMP calls already have an edge to exit.
5331 CONST and PURE calls do not need one.
5332 We don't currently check for CONST and PURE here, although
5333 it would be a good idea, because those attributes are
5334 figured out from the RTL in mark_constant_function, and
5335 the counter incrementation code from -fprofile-arcs
5336 leads to different results from -fbranch-probabilities. */
5337 call
= get_call_expr_in (t
);
5339 && !(call_expr_flags (call
) & ECF_NORETURN
))
5342 if (TREE_CODE (t
) == ASM_EXPR
5343 && (ASM_VOLATILE_P (t
) || ASM_INPUT_P (t
)))
5350 /* Add fake edges to the function exit for any non constant and non
5351 noreturn calls, volatile inline assembly in the bitmap of blocks
5352 specified by BLOCKS or to the whole CFG if BLOCKS is zero. Return
5353 the number of blocks that were split.
5355 The goal is to expose cases in which entering a basic block does
5356 not imply that all subsequent instructions must be executed. */
5359 tree_flow_call_edges_add (sbitmap blocks
)
5362 int blocks_split
= 0;
5363 int last_bb
= last_basic_block
;
5364 bool check_last_block
= false;
5366 if (n_basic_blocks
== 0)
5370 check_last_block
= true;
5372 check_last_block
= TEST_BIT (blocks
, EXIT_BLOCK_PTR
->prev_bb
->index
);
5374 /* In the last basic block, before epilogue generation, there will be
5375 a fallthru edge to EXIT. Special care is required if the last insn
5376 of the last basic block is a call because make_edge folds duplicate
5377 edges, which would result in the fallthru edge also being marked
5378 fake, which would result in the fallthru edge being removed by
5379 remove_fake_edges, which would result in an invalid CFG.
5381 Moreover, we can't elide the outgoing fake edge, since the block
5382 profiler needs to take this into account in order to solve the minimal
5383 spanning tree in the case that the call doesn't return.
5385 Handle this by adding a dummy instruction in a new last basic block. */
5386 if (check_last_block
)
5388 basic_block bb
= EXIT_BLOCK_PTR
->prev_bb
;
5389 block_stmt_iterator bsi
= bsi_last (bb
);
5391 if (!bsi_end_p (bsi
))
5394 if (need_fake_edge_p (t
))
5398 e
= find_edge (bb
, EXIT_BLOCK_PTR
);
5401 bsi_insert_on_edge (e
, build_empty_stmt ());
5402 bsi_commit_edge_inserts ();
5407 /* Now add fake edges to the function exit for any non constant
5408 calls since there is no way that we can determine if they will
5410 for (i
= 0; i
< last_bb
; i
++)
5412 basic_block bb
= BASIC_BLOCK (i
);
5413 block_stmt_iterator bsi
;
5414 tree stmt
, last_stmt
;
5419 if (blocks
&& !TEST_BIT (blocks
, i
))
5422 bsi
= bsi_last (bb
);
5423 if (!bsi_end_p (bsi
))
5425 last_stmt
= bsi_stmt (bsi
);
5428 stmt
= bsi_stmt (bsi
);
5429 if (need_fake_edge_p (stmt
))
5432 /* The handling above of the final block before the
5433 epilogue should be enough to verify that there is
5434 no edge to the exit block in CFG already.
5435 Calling make_edge in such case would cause us to
5436 mark that edge as fake and remove it later. */
5437 #ifdef ENABLE_CHECKING
5438 if (stmt
== last_stmt
)
5440 e
= find_edge (bb
, EXIT_BLOCK_PTR
);
5441 gcc_assert (e
== NULL
);
5445 /* Note that the following may create a new basic block
5446 and renumber the existing basic blocks. */
5447 if (stmt
!= last_stmt
)
5449 e
= split_block (bb
, stmt
);
5453 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
5457 while (!bsi_end_p (bsi
));
5462 verify_flow_info ();
5464 return blocks_split
;
5468 tree_purge_dead_eh_edges (basic_block bb
)
5470 bool changed
= false;
5473 tree stmt
= last_stmt (bb
);
5475 if (stmt
&& tree_can_throw_internal (stmt
))
5478 for (ei
= ei_start (bb
->succs
); (e
= ei_safe_edge (ei
)); )
5480 if (e
->flags
& EDGE_EH
)
5489 /* Removal of dead EH edges might change dominators of not
5490 just immediate successors. E.g. when bb1 is changed so that
5491 it no longer can throw and bb1->bb3 and bb1->bb4 are dead
5492 eh edges purged by this function in:
5504 idom(bb5) must be recomputed. For now just free the dominance
5507 free_dominance_info (CDI_DOMINATORS
);
5513 tree_purge_all_dead_eh_edges (bitmap blocks
)
5515 bool changed
= false;
5519 EXECUTE_IF_SET_IN_BITMAP (blocks
, 0, i
, bi
)
5521 changed
|= tree_purge_dead_eh_edges (BASIC_BLOCK (i
));
5527 /* This function is called whenever a new edge is created or
5531 tree_execute_on_growing_pred (edge e
)
5533 basic_block bb
= e
->dest
;
5536 reserve_phi_args_for_new_edge (bb
);
5539 /* This function is called immediately before edge E is removed from
5540 the edge vector E->dest->preds. */
5543 tree_execute_on_shrinking_pred (edge e
)
5545 if (phi_nodes (e
->dest
))
5546 remove_phi_args (e
);
5549 struct cfg_hooks tree_cfg_hooks
= {
5551 tree_verify_flow_info
,
5552 tree_dump_bb
, /* dump_bb */
5553 create_bb
, /* create_basic_block */
5554 tree_redirect_edge_and_branch
,/* redirect_edge_and_branch */
5555 tree_redirect_edge_and_branch_force
,/* redirect_edge_and_branch_force */
5556 remove_bb
, /* delete_basic_block */
5557 tree_split_block
, /* split_block */
5558 tree_move_block_after
, /* move_block_after */
5559 tree_can_merge_blocks_p
, /* can_merge_blocks_p */
5560 tree_merge_blocks
, /* merge_blocks */
5561 tree_predict_edge
, /* predict_edge */
5562 tree_predicted_by_p
, /* predicted_by_p */
5563 tree_can_duplicate_bb_p
, /* can_duplicate_block_p */
5564 tree_duplicate_bb
, /* duplicate_block */
5565 tree_split_edge
, /* split_edge */
5566 tree_make_forwarder_block
, /* make_forward_block */
5567 NULL
, /* tidy_fallthru_edge */
5568 tree_block_ends_with_call_p
, /* block_ends_with_call_p */
5569 tree_block_ends_with_condjump_p
, /* block_ends_with_condjump_p */
5570 tree_flow_call_edges_add
, /* flow_call_edges_add */
5571 tree_execute_on_growing_pred
, /* execute_on_growing_pred */
5572 tree_execute_on_shrinking_pred
, /* execute_on_shrinking_pred */
5576 /* Split all critical edges. */
5579 split_critical_edges (void)
5585 /* split_edge can redirect edges out of SWITCH_EXPRs, which can get
5586 expensive. So we want to enable recording of edge to CASE_LABEL_EXPR
5587 mappings around the calls to split_edge. */
5588 start_recording_case_labels ();
5591 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
5592 if (EDGE_CRITICAL_P (e
) && !(e
->flags
& EDGE_ABNORMAL
))
5597 end_recording_case_labels ();
5600 struct tree_opt_pass pass_split_crit_edges
=
5602 "crited", /* name */
5604 split_critical_edges
, /* execute */
5607 0, /* static_pass_number */
5608 TV_TREE_SPLIT_EDGES
, /* tv_id */
5609 PROP_cfg
, /* properties required */
5610 PROP_no_crit_edges
, /* properties_provided */
5611 0, /* properties_destroyed */
5612 0, /* todo_flags_start */
5613 TODO_dump_func
, /* todo_flags_finish */
5618 /* Return EXP if it is a valid GIMPLE rvalue, else gimplify it into
5619 a temporary, make sure and register it to be renamed if necessary,
5620 and finally return the temporary. Put the statements to compute
5621 EXP before the current statement in BSI. */
5624 gimplify_val (block_stmt_iterator
*bsi
, tree type
, tree exp
)
5626 tree t
, new_stmt
, orig_stmt
;
5628 if (is_gimple_val (exp
))
5631 t
= make_rename_temp (type
, NULL
);
5632 new_stmt
= build (MODIFY_EXPR
, type
, t
, exp
);
5634 orig_stmt
= bsi_stmt (*bsi
);
5635 SET_EXPR_LOCUS (new_stmt
, EXPR_LOCUS (orig_stmt
));
5636 TREE_BLOCK (new_stmt
) = TREE_BLOCK (orig_stmt
);
5638 bsi_insert_before (bsi
, new_stmt
, BSI_SAME_STMT
);
5643 /* Build a ternary operation and gimplify it. Emit code before BSI.
5644 Return the gimple_val holding the result. */
5647 gimplify_build3 (block_stmt_iterator
*bsi
, enum tree_code code
,
5648 tree type
, tree a
, tree b
, tree c
)
5652 ret
= fold (build3 (code
, type
, a
, b
, c
));
5655 return gimplify_val (bsi
, type
, ret
);
5658 /* Build a binary operation and gimplify it. Emit code before BSI.
5659 Return the gimple_val holding the result. */
5662 gimplify_build2 (block_stmt_iterator
*bsi
, enum tree_code code
,
5663 tree type
, tree a
, tree b
)
5667 ret
= fold (build2 (code
, type
, a
, b
));
5670 return gimplify_val (bsi
, type
, ret
);
5673 /* Build a unary operation and gimplify it. Emit code before BSI.
5674 Return the gimple_val holding the result. */
5677 gimplify_build1 (block_stmt_iterator
*bsi
, enum tree_code code
, tree type
,
5682 ret
= fold (build1 (code
, type
, a
));
5685 return gimplify_val (bsi
, type
, ret
);
5690 /* Emit return warnings. */
5693 execute_warn_function_return (void)
5695 #ifdef USE_MAPPED_LOCATION
5696 source_location location
;
5704 if (warn_missing_noreturn
5705 && !TREE_THIS_VOLATILE (cfun
->decl
)
5706 && EDGE_COUNT (EXIT_BLOCK_PTR
->preds
) == 0
5707 && !lang_hooks
.function
.missing_noreturn_ok_p (cfun
->decl
))
5708 warning ("%Jfunction might be possible candidate for "
5709 "attribute %<noreturn%>",
5712 /* If we have a path to EXIT, then we do return. */
5713 if (TREE_THIS_VOLATILE (cfun
->decl
)
5714 && EDGE_COUNT (EXIT_BLOCK_PTR
->preds
) > 0)
5716 #ifdef USE_MAPPED_LOCATION
5717 location
= UNKNOWN_LOCATION
;
5721 FOR_EACH_EDGE (e
, ei
, EXIT_BLOCK_PTR
->preds
)
5723 last
= last_stmt (e
->src
);
5724 if (TREE_CODE (last
) == RETURN_EXPR
5725 #ifdef USE_MAPPED_LOCATION
5726 && (location
= EXPR_LOCATION (last
)) != UNKNOWN_LOCATION
)
5728 && (locus
= EXPR_LOCUS (last
)) != NULL
)
5732 #ifdef USE_MAPPED_LOCATION
5733 if (location
== UNKNOWN_LOCATION
)
5734 location
= cfun
->function_end_locus
;
5735 warning ("%H%<noreturn%> function does return", &location
);
5738 locus
= &cfun
->function_end_locus
;
5739 warning ("%H%<noreturn%> function does return", locus
);
5743 /* If we see "return;" in some basic block, then we do reach the end
5744 without returning a value. */
5745 else if (warn_return_type
5746 && !TREE_NO_WARNING (cfun
->decl
)
5747 && EDGE_COUNT (EXIT_BLOCK_PTR
->preds
) > 0
5748 && !VOID_TYPE_P (TREE_TYPE (TREE_TYPE (cfun
->decl
))))
5750 FOR_EACH_EDGE (e
, ei
, EXIT_BLOCK_PTR
->preds
)
5752 tree last
= last_stmt (e
->src
);
5753 if (TREE_CODE (last
) == RETURN_EXPR
5754 && TREE_OPERAND (last
, 0) == NULL
)
5756 #ifdef USE_MAPPED_LOCATION
5757 location
= EXPR_LOCATION (last
);
5758 if (location
== UNKNOWN_LOCATION
)
5759 location
= cfun
->function_end_locus
;
5760 warning ("%Hcontrol reaches end of non-void function", &location
);
5762 locus
= EXPR_LOCUS (last
);
5764 locus
= &cfun
->function_end_locus
;
5765 warning ("%Hcontrol reaches end of non-void function", locus
);
5767 TREE_NO_WARNING (cfun
->decl
) = 1;
5775 /* Given a basic block B which ends with a conditional and has
5776 precisely two successors, determine which of the edges is taken if
5777 the conditional is true and which is taken if the conditional is
5778 false. Set TRUE_EDGE and FALSE_EDGE appropriately. */
5781 extract_true_false_edges_from_block (basic_block b
,
5785 edge e
= EDGE_SUCC (b
, 0);
5787 if (e
->flags
& EDGE_TRUE_VALUE
)
5790 *false_edge
= EDGE_SUCC (b
, 1);
5795 *true_edge
= EDGE_SUCC (b
, 1);
5799 struct tree_opt_pass pass_warn_function_return
=
5803 execute_warn_function_return
, /* execute */
5806 0, /* static_pass_number */
5808 PROP_cfg
, /* properties_required */
5809 0, /* properties_provided */
5810 0, /* properties_destroyed */
5811 0, /* todo_flags_start */
5812 0, /* todo_flags_finish */
5816 #include "gt-tree-cfg.h"