* optabs.c (no_conflict_move_test): Check if a result of a
[official-gcc.git] / gcc / tree-cfg.c
blobd5d466edf49f6b9021731d772623e490fbc65256
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)
10 any later version.
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, 51 Franklin Street, Fifth Floor,
20 Boston, MA 02110-1301, USA. */
22 #include "config.h"
23 #include "system.h"
24 #include "coretypes.h"
25 #include "tm.h"
26 #include "tree.h"
27 #include "rtl.h"
28 #include "tm_p.h"
29 #include "hard-reg-set.h"
30 #include "basic-block.h"
31 #include "output.h"
32 #include "flags.h"
33 #include "function.h"
34 #include "expr.h"
35 #include "ggc.h"
36 #include "langhooks.h"
37 #include "diagnostic.h"
38 #include "tree-flow.h"
39 #include "timevar.h"
40 #include "tree-dump.h"
41 #include "tree-pass.h"
42 #include "toplev.h"
43 #include "except.h"
44 #include "cfgloop.h"
45 #include "cfglayout.h"
46 #include "hashtab.h"
47 #include "tree-ssa-propagate.h"
49 /* This file contains functions for building the Control Flow Graph (CFG)
50 for a function tree. */
52 /* Local declarations. */
54 /* Initial capacity for the basic block array. */
55 static const int initial_cfg_capacity = 20;
57 /* This hash table allows us to efficiently lookup all CASE_LABEL_EXPRs
58 which use a particular edge. The CASE_LABEL_EXPRs are chained together
59 via their TREE_CHAIN field, which we clear after we're done with the
60 hash table to prevent problems with duplication of SWITCH_EXPRs.
62 Access to this list of CASE_LABEL_EXPRs allows us to efficiently
63 update the case vector in response to edge redirections.
65 Right now this table is set up and torn down at key points in the
66 compilation process. It would be nice if we could make the table
67 more persistent. The key is getting notification of changes to
68 the CFG (particularly edge removal, creation and redirection). */
70 struct edge_to_cases_elt
72 /* The edge itself. Necessary for hashing and equality tests. */
73 edge e;
75 /* The case labels associated with this edge. We link these up via
76 their TREE_CHAIN field, then we wipe out the TREE_CHAIN fields
77 when we destroy the hash table. This prevents problems when copying
78 SWITCH_EXPRs. */
79 tree case_labels;
82 static htab_t edge_to_cases;
84 /* CFG statistics. */
85 struct cfg_stats_d
87 long num_merged_labels;
90 static struct cfg_stats_d cfg_stats;
92 /* Nonzero if we found a computed goto while building basic blocks. */
93 static bool found_computed_goto;
95 /* Basic blocks and flowgraphs. */
96 static basic_block create_bb (void *, void *, basic_block);
97 static void make_blocks (tree);
98 static void factor_computed_gotos (void);
100 /* Edges. */
101 static void make_edges (void);
102 static void make_ctrl_stmt_edges (basic_block);
103 static void make_exit_edges (basic_block);
104 static void make_cond_expr_edges (basic_block);
105 static void make_switch_expr_edges (basic_block);
106 static void make_goto_expr_edges (basic_block);
107 static edge tree_redirect_edge_and_branch (edge, basic_block);
108 static edge tree_try_redirect_by_replacing_jump (edge, basic_block);
109 static void split_critical_edges (void);
111 /* Various helpers. */
112 static inline bool stmt_starts_bb_p (tree, tree);
113 static int tree_verify_flow_info (void);
114 static void tree_make_forwarder_block (edge);
115 static void tree_cfg2vcg (FILE *);
117 /* Flowgraph optimization and cleanup. */
118 static void tree_merge_blocks (basic_block, basic_block);
119 static bool tree_can_merge_blocks_p (basic_block, basic_block);
120 static void remove_bb (basic_block);
121 static edge find_taken_edge_computed_goto (basic_block, tree);
122 static edge find_taken_edge_cond_expr (basic_block, tree);
123 static edge find_taken_edge_switch_expr (basic_block, tree);
124 static tree find_case_label_for_value (tree, tree);
126 void
127 init_empty_tree_cfg (void)
129 /* Initialize the basic block array. */
130 init_flow ();
131 profile_status = PROFILE_ABSENT;
132 n_basic_blocks = 0;
133 last_basic_block = 0;
134 VARRAY_BB_INIT (basic_block_info, initial_cfg_capacity, "basic_block_info");
136 /* Build a mapping of labels to their associated blocks. */
137 VARRAY_BB_INIT (label_to_block_map, initial_cfg_capacity,
138 "label to block map");
140 ENTRY_BLOCK_PTR->next_bb = EXIT_BLOCK_PTR;
141 EXIT_BLOCK_PTR->prev_bb = ENTRY_BLOCK_PTR;
144 /*---------------------------------------------------------------------------
145 Create basic blocks
146 ---------------------------------------------------------------------------*/
148 /* Entry point to the CFG builder for trees. TP points to the list of
149 statements to be added to the flowgraph. */
151 static void
152 build_tree_cfg (tree *tp)
154 /* Register specific tree functions. */
155 tree_register_cfg_hooks ();
157 memset ((void *) &cfg_stats, 0, sizeof (cfg_stats));
159 init_empty_tree_cfg ();
161 found_computed_goto = 0;
162 make_blocks (*tp);
164 /* Computed gotos are hell to deal with, especially if there are
165 lots of them with a large number of destinations. So we factor
166 them to a common computed goto location before we build the
167 edge list. After we convert back to normal form, we will un-factor
168 the computed gotos since factoring introduces an unwanted jump. */
169 if (found_computed_goto)
170 factor_computed_gotos ();
172 /* Make sure there is always at least one block, even if it's empty. */
173 if (n_basic_blocks == 0)
174 create_empty_bb (ENTRY_BLOCK_PTR);
176 /* Adjust the size of the array. */
177 VARRAY_GROW (basic_block_info, n_basic_blocks);
179 /* To speed up statement iterator walks, we first purge dead labels. */
180 cleanup_dead_labels ();
182 /* Group case nodes to reduce the number of edges.
183 We do this after cleaning up dead labels because otherwise we miss
184 a lot of obvious case merging opportunities. */
185 group_case_labels ();
187 /* Create the edges of the flowgraph. */
188 make_edges ();
190 /* Debugging dumps. */
192 /* Write the flowgraph to a VCG file. */
194 int local_dump_flags;
195 FILE *dump_file = dump_begin (TDI_vcg, &local_dump_flags);
196 if (dump_file)
198 tree_cfg2vcg (dump_file);
199 dump_end (TDI_vcg, dump_file);
203 #ifdef ENABLE_CHECKING
204 verify_stmts ();
205 #endif
207 /* Dump a textual representation of the flowgraph. */
208 if (dump_file)
209 dump_tree_cfg (dump_file, dump_flags);
212 static void
213 execute_build_cfg (void)
215 build_tree_cfg (&DECL_SAVED_TREE (current_function_decl));
218 struct tree_opt_pass pass_build_cfg =
220 "cfg", /* name */
221 NULL, /* gate */
222 execute_build_cfg, /* execute */
223 NULL, /* sub */
224 NULL, /* next */
225 0, /* static_pass_number */
226 TV_TREE_CFG, /* tv_id */
227 PROP_gimple_leh, /* properties_required */
228 PROP_cfg, /* properties_provided */
229 0, /* properties_destroyed */
230 0, /* todo_flags_start */
231 TODO_verify_stmts, /* todo_flags_finish */
232 0 /* letter */
235 /* Search the CFG for any computed gotos. If found, factor them to a
236 common computed goto site. Also record the location of that site so
237 that we can un-factor the gotos after we have converted back to
238 normal form. */
240 static void
241 factor_computed_gotos (void)
243 basic_block bb;
244 tree factored_label_decl = NULL;
245 tree var = NULL;
246 tree factored_computed_goto_label = NULL;
247 tree factored_computed_goto = NULL;
249 /* We know there are one or more computed gotos in this function.
250 Examine the last statement in each basic block to see if the block
251 ends with a computed goto. */
253 FOR_EACH_BB (bb)
255 block_stmt_iterator bsi = bsi_last (bb);
256 tree last;
258 if (bsi_end_p (bsi))
259 continue;
260 last = bsi_stmt (bsi);
262 /* Ignore the computed goto we create when we factor the original
263 computed gotos. */
264 if (last == factored_computed_goto)
265 continue;
267 /* If the last statement is a computed goto, factor it. */
268 if (computed_goto_p (last))
270 tree assignment;
272 /* The first time we find a computed goto we need to create
273 the factored goto block and the variable each original
274 computed goto will use for their goto destination. */
275 if (! factored_computed_goto)
277 basic_block new_bb = create_empty_bb (bb);
278 block_stmt_iterator new_bsi = bsi_start (new_bb);
280 /* Create the destination of the factored goto. Each original
281 computed goto will put its desired destination into this
282 variable and jump to the label we create immediately
283 below. */
284 var = create_tmp_var (ptr_type_node, "gotovar");
286 /* Build a label for the new block which will contain the
287 factored computed goto. */
288 factored_label_decl = create_artificial_label ();
289 factored_computed_goto_label
290 = build1 (LABEL_EXPR, void_type_node, factored_label_decl);
291 bsi_insert_after (&new_bsi, factored_computed_goto_label,
292 BSI_NEW_STMT);
294 /* Build our new computed goto. */
295 factored_computed_goto = build1 (GOTO_EXPR, void_type_node, var);
296 bsi_insert_after (&new_bsi, factored_computed_goto,
297 BSI_NEW_STMT);
300 /* Copy the original computed goto's destination into VAR. */
301 assignment = build (MODIFY_EXPR, ptr_type_node,
302 var, GOTO_DESTINATION (last));
303 bsi_insert_before (&bsi, assignment, BSI_SAME_STMT);
305 /* And re-vector the computed goto to the new destination. */
306 GOTO_DESTINATION (last) = factored_label_decl;
312 /* Build a flowgraph for the statement_list STMT_LIST. */
314 static void
315 make_blocks (tree stmt_list)
317 tree_stmt_iterator i = tsi_start (stmt_list);
318 tree stmt = NULL;
319 bool start_new_block = true;
320 bool first_stmt_of_list = true;
321 basic_block bb = ENTRY_BLOCK_PTR;
323 while (!tsi_end_p (i))
325 tree prev_stmt;
327 prev_stmt = stmt;
328 stmt = tsi_stmt (i);
330 /* If the statement starts a new basic block or if we have determined
331 in a previous pass that we need to create a new block for STMT, do
332 so now. */
333 if (start_new_block || stmt_starts_bb_p (stmt, prev_stmt))
335 if (!first_stmt_of_list)
336 stmt_list = tsi_split_statement_list_before (&i);
337 bb = create_basic_block (stmt_list, NULL, bb);
338 start_new_block = false;
341 /* Now add STMT to BB and create the subgraphs for special statement
342 codes. */
343 set_bb_for_stmt (stmt, bb);
345 if (computed_goto_p (stmt))
346 found_computed_goto = true;
348 /* If STMT is a basic block terminator, set START_NEW_BLOCK for the
349 next iteration. */
350 if (stmt_ends_bb_p (stmt))
351 start_new_block = true;
353 tsi_next (&i);
354 first_stmt_of_list = false;
359 /* Create and return a new empty basic block after bb AFTER. */
361 static basic_block
362 create_bb (void *h, void *e, basic_block after)
364 basic_block bb;
366 gcc_assert (!e);
368 /* Create and initialize a new basic block. Since alloc_block uses
369 ggc_alloc_cleared to allocate a basic block, we do not have to
370 clear the newly allocated basic block here. */
371 bb = alloc_block ();
373 bb->index = last_basic_block;
374 bb->flags = BB_NEW;
375 bb->stmt_list = h ? h : alloc_stmt_list ();
377 /* Add the new block to the linked list of blocks. */
378 link_block (bb, after);
380 /* Grow the basic block array if needed. */
381 if ((size_t) last_basic_block == VARRAY_SIZE (basic_block_info))
383 size_t new_size = last_basic_block + (last_basic_block + 3) / 4;
384 VARRAY_GROW (basic_block_info, new_size);
387 /* Add the newly created block to the array. */
388 BASIC_BLOCK (last_basic_block) = bb;
390 n_basic_blocks++;
391 last_basic_block++;
393 return bb;
397 /*---------------------------------------------------------------------------
398 Edge creation
399 ---------------------------------------------------------------------------*/
401 /* Fold COND_EXPR_COND of each COND_EXPR. */
403 void
404 fold_cond_expr_cond (void)
406 basic_block bb;
408 FOR_EACH_BB (bb)
410 tree stmt = last_stmt (bb);
412 if (stmt
413 && TREE_CODE (stmt) == COND_EXPR)
415 tree cond = fold (COND_EXPR_COND (stmt));
416 if (integer_zerop (cond))
417 COND_EXPR_COND (stmt) = boolean_false_node;
418 else if (integer_onep (cond))
419 COND_EXPR_COND (stmt) = boolean_true_node;
424 /* Join all the blocks in the flowgraph. */
426 static void
427 make_edges (void)
429 basic_block bb;
431 /* Create an edge from entry to the first block with executable
432 statements in it. */
433 make_edge (ENTRY_BLOCK_PTR, BASIC_BLOCK (0), EDGE_FALLTHRU);
435 /* Traverse the basic block array placing edges. */
436 FOR_EACH_BB (bb)
438 tree first = first_stmt (bb);
439 tree last = last_stmt (bb);
441 if (first)
443 /* Edges for statements that always alter flow control. */
444 if (is_ctrl_stmt (last))
445 make_ctrl_stmt_edges (bb);
447 /* Edges for statements that sometimes alter flow control. */
448 if (is_ctrl_altering_stmt (last))
449 make_exit_edges (bb);
452 /* Finally, if no edges were created above, this is a regular
453 basic block that only needs a fallthru edge. */
454 if (EDGE_COUNT (bb->succs) == 0)
455 make_edge (bb, bb->next_bb, EDGE_FALLTHRU);
458 /* We do not care about fake edges, so remove any that the CFG
459 builder inserted for completeness. */
460 remove_fake_exit_edges ();
462 /* Fold COND_EXPR_COND of each COND_EXPR. */
463 fold_cond_expr_cond ();
465 /* Clean up the graph and warn for unreachable code. */
466 cleanup_tree_cfg ();
470 /* Create edges for control statement at basic block BB. */
472 static void
473 make_ctrl_stmt_edges (basic_block bb)
475 tree last = last_stmt (bb);
477 gcc_assert (last);
478 switch (TREE_CODE (last))
480 case GOTO_EXPR:
481 make_goto_expr_edges (bb);
482 break;
484 case RETURN_EXPR:
485 make_edge (bb, EXIT_BLOCK_PTR, 0);
486 break;
488 case COND_EXPR:
489 make_cond_expr_edges (bb);
490 break;
492 case SWITCH_EXPR:
493 make_switch_expr_edges (bb);
494 break;
496 case RESX_EXPR:
497 make_eh_edges (last);
498 /* Yet another NORETURN hack. */
499 if (EDGE_COUNT (bb->succs) == 0)
500 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
501 break;
503 default:
504 gcc_unreachable ();
509 /* Create exit edges for statements in block BB that alter the flow of
510 control. Statements that alter the control flow are 'goto', 'return'
511 and calls to non-returning functions. */
513 static void
514 make_exit_edges (basic_block bb)
516 tree last = last_stmt (bb), op;
518 gcc_assert (last);
519 switch (TREE_CODE (last))
521 case RESX_EXPR:
522 break;
523 case CALL_EXPR:
524 /* If this function receives a nonlocal goto, then we need to
525 make edges from this call site to all the nonlocal goto
526 handlers. */
527 if (TREE_SIDE_EFFECTS (last)
528 && current_function_has_nonlocal_label)
529 make_goto_expr_edges (bb);
531 /* If this statement has reachable exception handlers, then
532 create abnormal edges to them. */
533 make_eh_edges (last);
535 /* Some calls are known not to return. For such calls we create
536 a fake edge.
538 We really need to revamp how we build edges so that it's not
539 such a bloody pain to avoid creating edges for this case since
540 all we do is remove these edges when we're done building the
541 CFG. */
542 if (call_expr_flags (last) & ECF_NORETURN)
544 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
545 return;
548 /* Don't forget the fall-thru edge. */
549 make_edge (bb, bb->next_bb, EDGE_FALLTHRU);
550 break;
552 case MODIFY_EXPR:
553 /* A MODIFY_EXPR may have a CALL_EXPR on its RHS and the CALL_EXPR
554 may have an abnormal edge. Search the RHS for this case and
555 create any required edges. */
556 op = get_call_expr_in (last);
557 if (op && TREE_SIDE_EFFECTS (op)
558 && current_function_has_nonlocal_label)
559 make_goto_expr_edges (bb);
561 make_eh_edges (last);
562 make_edge (bb, bb->next_bb, EDGE_FALLTHRU);
563 break;
565 default:
566 gcc_unreachable ();
571 /* Create the edges for a COND_EXPR starting at block BB.
572 At this point, both clauses must contain only simple gotos. */
574 static void
575 make_cond_expr_edges (basic_block bb)
577 tree entry = last_stmt (bb);
578 basic_block then_bb, else_bb;
579 tree then_label, else_label;
580 edge e;
582 gcc_assert (entry);
583 gcc_assert (TREE_CODE (entry) == COND_EXPR);
585 /* Entry basic blocks for each component. */
586 then_label = GOTO_DESTINATION (COND_EXPR_THEN (entry));
587 else_label = GOTO_DESTINATION (COND_EXPR_ELSE (entry));
588 then_bb = label_to_block (then_label);
589 else_bb = label_to_block (else_label);
591 e = make_edge (bb, then_bb, EDGE_TRUE_VALUE);
592 #ifdef USE_MAPPED_LOCATION
593 e->goto_locus = EXPR_LOCATION (COND_EXPR_THEN (entry));
594 #else
595 e->goto_locus = EXPR_LOCUS (COND_EXPR_THEN (entry));
596 #endif
597 e = make_edge (bb, else_bb, EDGE_FALSE_VALUE);
598 if (e)
600 #ifdef USE_MAPPED_LOCATION
601 e->goto_locus = EXPR_LOCATION (COND_EXPR_ELSE (entry));
602 #else
603 e->goto_locus = EXPR_LOCUS (COND_EXPR_ELSE (entry));
604 #endif
608 /* Hashing routine for EDGE_TO_CASES. */
610 static hashval_t
611 edge_to_cases_hash (const void *p)
613 edge e = ((struct edge_to_cases_elt *)p)->e;
615 /* Hash on the edge itself (which is a pointer). */
616 return htab_hash_pointer (e);
619 /* Equality routine for EDGE_TO_CASES, edges are unique, so testing
620 for equality is just a pointer comparison. */
622 static int
623 edge_to_cases_eq (const void *p1, const void *p2)
625 edge e1 = ((struct edge_to_cases_elt *)p1)->e;
626 edge e2 = ((struct edge_to_cases_elt *)p2)->e;
628 return e1 == e2;
631 /* Called for each element in the hash table (P) as we delete the
632 edge to cases hash table.
634 Clear all the TREE_CHAINs to prevent problems with copying of
635 SWITCH_EXPRs and structure sharing rules, then free the hash table
636 element. */
638 static void
639 edge_to_cases_cleanup (void *p)
641 struct edge_to_cases_elt *elt = p;
642 tree t, next;
644 for (t = elt->case_labels; t; t = next)
646 next = TREE_CHAIN (t);
647 TREE_CHAIN (t) = NULL;
649 free (p);
652 /* Start recording information mapping edges to case labels. */
654 void
655 start_recording_case_labels (void)
657 gcc_assert (edge_to_cases == NULL);
659 edge_to_cases = htab_create (37,
660 edge_to_cases_hash,
661 edge_to_cases_eq,
662 edge_to_cases_cleanup);
665 /* Return nonzero if we are recording information for case labels. */
667 static bool
668 recording_case_labels_p (void)
670 return (edge_to_cases != NULL);
673 /* Stop recording information mapping edges to case labels and
674 remove any information we have recorded. */
675 void
676 end_recording_case_labels (void)
678 htab_delete (edge_to_cases);
679 edge_to_cases = NULL;
682 /* Record that CASE_LABEL (a CASE_LABEL_EXPR) references edge E. */
684 static void
685 record_switch_edge (edge e, tree case_label)
687 struct edge_to_cases_elt *elt;
688 void **slot;
690 /* Build a hash table element so we can see if E is already
691 in the table. */
692 elt = xmalloc (sizeof (struct edge_to_cases_elt));
693 elt->e = e;
694 elt->case_labels = case_label;
696 slot = htab_find_slot (edge_to_cases, elt, INSERT);
698 if (*slot == NULL)
700 /* E was not in the hash table. Install E into the hash table. */
701 *slot = (void *)elt;
703 else
705 /* E was already in the hash table. Free ELT as we do not need it
706 anymore. */
707 free (elt);
709 /* Get the entry stored in the hash table. */
710 elt = (struct edge_to_cases_elt *) *slot;
712 /* Add it to the chain of CASE_LABEL_EXPRs referencing E. */
713 TREE_CHAIN (case_label) = elt->case_labels;
714 elt->case_labels = case_label;
718 /* If we are inside a {start,end}_recording_cases block, then return
719 a chain of CASE_LABEL_EXPRs from T which reference E.
721 Otherwise return NULL. */
723 static tree
724 get_cases_for_edge (edge e, tree t)
726 struct edge_to_cases_elt elt, *elt_p;
727 void **slot;
728 size_t i, n;
729 tree vec;
731 /* If we are not recording cases, then we do not have CASE_LABEL_EXPR
732 chains available. Return NULL so the caller can detect this case. */
733 if (!recording_case_labels_p ())
734 return NULL;
736 restart:
737 elt.e = e;
738 elt.case_labels = NULL;
739 slot = htab_find_slot (edge_to_cases, &elt, NO_INSERT);
741 if (slot)
743 elt_p = (struct edge_to_cases_elt *)*slot;
744 return elt_p->case_labels;
747 /* If we did not find E in the hash table, then this must be the first
748 time we have been queried for information about E & T. Add all the
749 elements from T to the hash table then perform the query again. */
751 vec = SWITCH_LABELS (t);
752 n = TREE_VEC_LENGTH (vec);
753 for (i = 0; i < n; i++)
755 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
756 basic_block label_bb = label_to_block (lab);
757 record_switch_edge (find_edge (e->src, label_bb), TREE_VEC_ELT (vec, i));
759 goto restart;
762 /* Create the edges for a SWITCH_EXPR starting at block BB.
763 At this point, the switch body has been lowered and the
764 SWITCH_LABELS filled in, so this is in effect a multi-way branch. */
766 static void
767 make_switch_expr_edges (basic_block bb)
769 tree entry = last_stmt (bb);
770 size_t i, n;
771 tree vec;
773 vec = SWITCH_LABELS (entry);
774 n = TREE_VEC_LENGTH (vec);
776 for (i = 0; i < n; ++i)
778 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
779 basic_block label_bb = label_to_block (lab);
780 make_edge (bb, label_bb, 0);
785 /* Return the basic block holding label DEST. */
787 basic_block
788 label_to_block_fn (struct function *ifun, tree dest)
790 int uid = LABEL_DECL_UID (dest);
792 /* We would die hard when faced by an undefined label. Emit a label to
793 the very first basic block. This will hopefully make even the dataflow
794 and undefined variable warnings quite right. */
795 if ((errorcount || sorrycount) && uid < 0)
797 block_stmt_iterator bsi = bsi_start (BASIC_BLOCK (0));
798 tree stmt;
800 stmt = build1 (LABEL_EXPR, void_type_node, dest);
801 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
802 uid = LABEL_DECL_UID (dest);
804 if (VARRAY_SIZE (ifun->cfg->x_label_to_block_map) <= (unsigned int)uid)
805 return NULL;
806 return VARRAY_BB (ifun->cfg->x_label_to_block_map, uid);
809 /* Create edges for a goto statement at block BB. */
811 static void
812 make_goto_expr_edges (basic_block bb)
814 tree goto_t;
815 basic_block target_bb;
816 int for_call;
817 block_stmt_iterator last = bsi_last (bb);
819 goto_t = bsi_stmt (last);
821 /* If the last statement is not a GOTO (i.e., it is a RETURN_EXPR,
822 CALL_EXPR or MODIFY_EXPR), then the edge is an abnormal edge resulting
823 from a nonlocal goto. */
824 if (TREE_CODE (goto_t) != GOTO_EXPR)
825 for_call = 1;
826 else
828 tree dest = GOTO_DESTINATION (goto_t);
829 for_call = 0;
831 /* A GOTO to a local label creates normal edges. */
832 if (simple_goto_p (goto_t))
834 edge e = make_edge (bb, label_to_block (dest), EDGE_FALLTHRU);
835 #ifdef USE_MAPPED_LOCATION
836 e->goto_locus = EXPR_LOCATION (goto_t);
837 #else
838 e->goto_locus = EXPR_LOCUS (goto_t);
839 #endif
840 bsi_remove (&last);
841 return;
844 /* Nothing more to do for nonlocal gotos. */
845 if (TREE_CODE (dest) == LABEL_DECL)
846 return;
848 /* Computed gotos remain. */
851 /* Look for the block starting with the destination label. In the
852 case of a computed goto, make an edge to any label block we find
853 in the CFG. */
854 FOR_EACH_BB (target_bb)
856 block_stmt_iterator bsi;
858 for (bsi = bsi_start (target_bb); !bsi_end_p (bsi); bsi_next (&bsi))
860 tree target = bsi_stmt (bsi);
862 if (TREE_CODE (target) != LABEL_EXPR)
863 break;
865 if (
866 /* Computed GOTOs. Make an edge to every label block that has
867 been marked as a potential target for a computed goto. */
868 (FORCED_LABEL (LABEL_EXPR_LABEL (target)) && for_call == 0)
869 /* Nonlocal GOTO target. Make an edge to every label block
870 that has been marked as a potential target for a nonlocal
871 goto. */
872 || (DECL_NONLOCAL (LABEL_EXPR_LABEL (target)) && for_call == 1))
874 make_edge (bb, target_bb, EDGE_ABNORMAL);
875 break;
880 /* Degenerate case of computed goto with no labels. */
881 if (!for_call && EDGE_COUNT (bb->succs) == 0)
882 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
886 /*---------------------------------------------------------------------------
887 Flowgraph analysis
888 ---------------------------------------------------------------------------*/
890 /* Cleanup useless labels in basic blocks. This is something we wish
891 to do early because it allows us to group case labels before creating
892 the edges for the CFG, and it speeds up block statement iterators in
893 all passes later on.
894 We only run this pass once, running it more than once is probably not
895 profitable. */
897 /* A map from basic block index to the leading label of that block. */
898 static tree *label_for_bb;
900 /* Callback for for_each_eh_region. Helper for cleanup_dead_labels. */
901 static void
902 update_eh_label (struct eh_region *region)
904 tree old_label = get_eh_region_tree_label (region);
905 if (old_label)
907 tree new_label;
908 basic_block bb = label_to_block (old_label);
910 /* ??? After optimizing, there may be EH regions with labels
911 that have already been removed from the function body, so
912 there is no basic block for them. */
913 if (! bb)
914 return;
916 new_label = label_for_bb[bb->index];
917 set_eh_region_tree_label (region, new_label);
921 /* Given LABEL return the first label in the same basic block. */
922 static tree
923 main_block_label (tree label)
925 basic_block bb = label_to_block (label);
927 /* label_to_block possibly inserted undefined label into the chain. */
928 if (!label_for_bb[bb->index])
929 label_for_bb[bb->index] = label;
930 return label_for_bb[bb->index];
933 /* Cleanup redundant labels. This is a three-step process:
934 1) Find the leading label for each block.
935 2) Redirect all references to labels to the leading labels.
936 3) Cleanup all useless labels. */
938 void
939 cleanup_dead_labels (void)
941 basic_block bb;
942 label_for_bb = xcalloc (last_basic_block, sizeof (tree));
944 /* Find a suitable label for each block. We use the first user-defined
945 label if there is one, or otherwise just the first label we see. */
946 FOR_EACH_BB (bb)
948 block_stmt_iterator i;
950 for (i = bsi_start (bb); !bsi_end_p (i); bsi_next (&i))
952 tree label, stmt = bsi_stmt (i);
954 if (TREE_CODE (stmt) != LABEL_EXPR)
955 break;
957 label = LABEL_EXPR_LABEL (stmt);
959 /* If we have not yet seen a label for the current block,
960 remember this one and see if there are more labels. */
961 if (! label_for_bb[bb->index])
963 label_for_bb[bb->index] = label;
964 continue;
967 /* If we did see a label for the current block already, but it
968 is an artificially created label, replace it if the current
969 label is a user defined label. */
970 if (! DECL_ARTIFICIAL (label)
971 && DECL_ARTIFICIAL (label_for_bb[bb->index]))
973 label_for_bb[bb->index] = label;
974 break;
979 /* Now redirect all jumps/branches to the selected label.
980 First do so for each block ending in a control statement. */
981 FOR_EACH_BB (bb)
983 tree stmt = last_stmt (bb);
984 if (!stmt)
985 continue;
987 switch (TREE_CODE (stmt))
989 case COND_EXPR:
991 tree true_branch, false_branch;
993 true_branch = COND_EXPR_THEN (stmt);
994 false_branch = COND_EXPR_ELSE (stmt);
996 GOTO_DESTINATION (true_branch)
997 = main_block_label (GOTO_DESTINATION (true_branch));
998 GOTO_DESTINATION (false_branch)
999 = main_block_label (GOTO_DESTINATION (false_branch));
1001 break;
1004 case SWITCH_EXPR:
1006 size_t i;
1007 tree vec = SWITCH_LABELS (stmt);
1008 size_t n = TREE_VEC_LENGTH (vec);
1010 /* Replace all destination labels. */
1011 for (i = 0; i < n; ++i)
1013 tree elt = TREE_VEC_ELT (vec, i);
1014 tree label = main_block_label (CASE_LABEL (elt));
1015 CASE_LABEL (elt) = label;
1017 break;
1020 /* We have to handle GOTO_EXPRs until they're removed, and we don't
1021 remove them until after we've created the CFG edges. */
1022 case GOTO_EXPR:
1023 if (! computed_goto_p (stmt))
1025 GOTO_DESTINATION (stmt)
1026 = main_block_label (GOTO_DESTINATION (stmt));
1027 break;
1030 default:
1031 break;
1035 for_each_eh_region (update_eh_label);
1037 /* Finally, purge dead labels. All user-defined labels and labels that
1038 can be the target of non-local gotos are preserved. */
1039 FOR_EACH_BB (bb)
1041 block_stmt_iterator i;
1042 tree label_for_this_bb = label_for_bb[bb->index];
1044 if (! label_for_this_bb)
1045 continue;
1047 for (i = bsi_start (bb); !bsi_end_p (i); )
1049 tree label, stmt = bsi_stmt (i);
1051 if (TREE_CODE (stmt) != LABEL_EXPR)
1052 break;
1054 label = LABEL_EXPR_LABEL (stmt);
1056 if (label == label_for_this_bb
1057 || ! DECL_ARTIFICIAL (label)
1058 || DECL_NONLOCAL (label))
1059 bsi_next (&i);
1060 else
1061 bsi_remove (&i);
1065 free (label_for_bb);
1068 /* Look for blocks ending in a multiway branch (a SWITCH_EXPR in GIMPLE),
1069 and scan the sorted vector of cases. Combine the ones jumping to the
1070 same label.
1071 Eg. three separate entries 1: 2: 3: become one entry 1..3: */
1073 void
1074 group_case_labels (void)
1076 basic_block bb;
1078 FOR_EACH_BB (bb)
1080 tree stmt = last_stmt (bb);
1081 if (stmt && TREE_CODE (stmt) == SWITCH_EXPR)
1083 tree labels = SWITCH_LABELS (stmt);
1084 int old_size = TREE_VEC_LENGTH (labels);
1085 int i, j, new_size = old_size;
1086 tree default_case = TREE_VEC_ELT (labels, old_size - 1);
1087 tree default_label;
1089 /* The default label is always the last case in a switch
1090 statement after gimplification. */
1091 default_label = CASE_LABEL (default_case);
1093 /* Look for possible opportunities to merge cases.
1094 Ignore the last element of the label vector because it
1095 must be the default case. */
1096 i = 0;
1097 while (i < old_size - 1)
1099 tree base_case, base_label, base_high;
1100 base_case = TREE_VEC_ELT (labels, i);
1102 gcc_assert (base_case);
1103 base_label = CASE_LABEL (base_case);
1105 /* Discard cases that have the same destination as the
1106 default case. */
1107 if (base_label == default_label)
1109 TREE_VEC_ELT (labels, i) = NULL_TREE;
1110 i++;
1111 new_size--;
1112 continue;
1115 base_high = CASE_HIGH (base_case) ?
1116 CASE_HIGH (base_case) : CASE_LOW (base_case);
1117 i++;
1118 /* Try to merge case labels. Break out when we reach the end
1119 of the label vector or when we cannot merge the next case
1120 label with the current one. */
1121 while (i < old_size - 1)
1123 tree merge_case = TREE_VEC_ELT (labels, i);
1124 tree merge_label = CASE_LABEL (merge_case);
1125 tree t = int_const_binop (PLUS_EXPR, base_high,
1126 integer_one_node, 1);
1128 /* Merge the cases if they jump to the same place,
1129 and their ranges are consecutive. */
1130 if (merge_label == base_label
1131 && tree_int_cst_equal (CASE_LOW (merge_case), t))
1133 base_high = CASE_HIGH (merge_case) ?
1134 CASE_HIGH (merge_case) : CASE_LOW (merge_case);
1135 CASE_HIGH (base_case) = base_high;
1136 TREE_VEC_ELT (labels, i) = NULL_TREE;
1137 new_size--;
1138 i++;
1140 else
1141 break;
1145 /* Compress the case labels in the label vector, and adjust the
1146 length of the vector. */
1147 for (i = 0, j = 0; i < new_size; i++)
1149 while (! TREE_VEC_ELT (labels, j))
1150 j++;
1151 TREE_VEC_ELT (labels, i) = TREE_VEC_ELT (labels, j++);
1153 TREE_VEC_LENGTH (labels) = new_size;
1158 /* Checks whether we can merge block B into block A. */
1160 static bool
1161 tree_can_merge_blocks_p (basic_block a, basic_block b)
1163 tree stmt;
1164 block_stmt_iterator bsi;
1165 tree phi;
1167 if (!single_succ_p (a))
1168 return false;
1170 if (single_succ_edge (a)->flags & EDGE_ABNORMAL)
1171 return false;
1173 if (single_succ (a) != b)
1174 return false;
1176 if (!single_pred_p (b))
1177 return false;
1179 if (b == EXIT_BLOCK_PTR)
1180 return false;
1182 /* If A ends by a statement causing exceptions or something similar, we
1183 cannot merge the blocks. */
1184 stmt = last_stmt (a);
1185 if (stmt && stmt_ends_bb_p (stmt))
1186 return false;
1188 /* Do not allow a block with only a non-local label to be merged. */
1189 if (stmt && TREE_CODE (stmt) == LABEL_EXPR
1190 && DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)))
1191 return false;
1193 /* It must be possible to eliminate all phi nodes in B. If ssa form
1194 is not up-to-date, we cannot eliminate any phis. */
1195 phi = phi_nodes (b);
1196 if (phi)
1198 if (need_ssa_update_p ())
1199 return false;
1201 for (; phi; phi = PHI_CHAIN (phi))
1202 if (!is_gimple_reg (PHI_RESULT (phi))
1203 && !may_propagate_copy (PHI_RESULT (phi), PHI_ARG_DEF (phi, 0)))
1204 return false;
1207 /* Do not remove user labels. */
1208 for (bsi = bsi_start (b); !bsi_end_p (bsi); bsi_next (&bsi))
1210 stmt = bsi_stmt (bsi);
1211 if (TREE_CODE (stmt) != LABEL_EXPR)
1212 break;
1213 if (!DECL_ARTIFICIAL (LABEL_EXPR_LABEL (stmt)))
1214 return false;
1217 /* Protect the loop latches. */
1218 if (current_loops
1219 && b->loop_father->latch == b)
1220 return false;
1222 return true;
1225 /* Replaces all uses of NAME by VAL. */
1227 void
1228 replace_uses_by (tree name, tree val)
1230 imm_use_iterator imm_iter;
1231 use_operand_p use;
1232 tree stmt;
1233 edge e;
1234 unsigned i;
1235 VEC(tree,heap) *stmts = VEC_alloc (tree, heap, 20);
1237 FOR_EACH_IMM_USE_SAFE (use, imm_iter, name)
1239 stmt = USE_STMT (use);
1240 replace_exp (use, val);
1242 if (TREE_CODE (stmt) == PHI_NODE)
1244 e = PHI_ARG_EDGE (stmt, PHI_ARG_INDEX_FROM_USE (use));
1245 if (e->flags & EDGE_ABNORMAL)
1247 /* This can only occur for virtual operands, since
1248 for the real ones SSA_NAME_OCCURS_IN_ABNORMAL_PHI (name))
1249 would prevent replacement. */
1250 gcc_assert (!is_gimple_reg (name));
1251 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (val) = 1;
1254 else
1255 VEC_safe_push (tree, heap, stmts, stmt);
1258 /* We do not update the statements in the loop above. Consider
1259 x = w * w;
1261 If we performed the update in the first loop, the statement
1262 would be rescanned after first occurrence of w is replaced,
1263 the new uses would be placed to the beginning of the list,
1264 and we would never process them. */
1265 for (i = 0; VEC_iterate (tree, stmts, i, stmt); i++)
1267 tree rhs;
1269 fold_stmt_inplace (stmt);
1271 rhs = get_rhs (stmt);
1272 if (TREE_CODE (rhs) == ADDR_EXPR)
1273 recompute_tree_invarant_for_addr_expr (rhs);
1275 /* If the statement could throw and now cannot, we need to prune cfg. */
1276 if (maybe_clean_or_replace_eh_stmt (stmt, stmt))
1277 tree_purge_dead_eh_edges (bb_for_stmt (stmt));
1279 mark_new_vars_to_rename (stmt);
1282 VEC_free (tree, heap, stmts);
1284 /* Also update the trees stored in loop structures. */
1285 if (current_loops)
1287 struct loop *loop;
1289 for (i = 0; i < current_loops->num; i++)
1291 loop = current_loops->parray[i];
1292 if (loop)
1293 substitute_in_loop_info (loop, name, val);
1298 /* Merge block B into block A. */
1300 static void
1301 tree_merge_blocks (basic_block a, basic_block b)
1303 block_stmt_iterator bsi;
1304 tree_stmt_iterator last;
1305 tree phi;
1307 if (dump_file)
1308 fprintf (dump_file, "Merging blocks %d and %d\n", a->index, b->index);
1310 /* Remove all single-valued PHI nodes from block B of the form
1311 V_i = PHI <V_j> by propagating V_j to all the uses of V_i. */
1312 bsi = bsi_last (a);
1313 for (phi = phi_nodes (b); phi; phi = phi_nodes (b))
1315 tree def = PHI_RESULT (phi), use = PHI_ARG_DEF (phi, 0);
1316 tree copy;
1317 bool may_replace_uses = may_propagate_copy (def, use);
1319 /* In case we have loops to care about, do not propagate arguments of
1320 loop closed ssa phi nodes. */
1321 if (current_loops
1322 && is_gimple_reg (def)
1323 && TREE_CODE (use) == SSA_NAME
1324 && a->loop_father != b->loop_father)
1325 may_replace_uses = false;
1327 if (!may_replace_uses)
1329 gcc_assert (is_gimple_reg (def));
1331 /* Note that just emitting the copies is fine -- there is no problem
1332 with ordering of phi nodes. This is because A is the single
1333 predecessor of B, therefore results of the phi nodes cannot
1334 appear as arguments of the phi nodes. */
1335 copy = build2 (MODIFY_EXPR, void_type_node, def, use);
1336 bsi_insert_after (&bsi, copy, BSI_NEW_STMT);
1337 SET_PHI_RESULT (phi, NULL_TREE);
1338 SSA_NAME_DEF_STMT (def) = copy;
1340 else
1341 replace_uses_by (def, use);
1343 remove_phi_node (phi, NULL);
1346 /* Ensure that B follows A. */
1347 move_block_after (b, a);
1349 gcc_assert (single_succ_edge (a)->flags & EDGE_FALLTHRU);
1350 gcc_assert (!last_stmt (a) || !stmt_ends_bb_p (last_stmt (a)));
1352 /* Remove labels from B and set bb_for_stmt to A for other statements. */
1353 for (bsi = bsi_start (b); !bsi_end_p (bsi);)
1355 if (TREE_CODE (bsi_stmt (bsi)) == LABEL_EXPR)
1357 tree label = bsi_stmt (bsi);
1359 bsi_remove (&bsi);
1360 /* Now that we can thread computed gotos, we might have
1361 a situation where we have a forced label in block B
1362 However, the label at the start of block B might still be
1363 used in other ways (think about the runtime checking for
1364 Fortran assigned gotos). So we can not just delete the
1365 label. Instead we move the label to the start of block A. */
1366 if (FORCED_LABEL (LABEL_EXPR_LABEL (label)))
1368 block_stmt_iterator dest_bsi = bsi_start (a);
1369 bsi_insert_before (&dest_bsi, label, BSI_NEW_STMT);
1372 else
1374 set_bb_for_stmt (bsi_stmt (bsi), a);
1375 bsi_next (&bsi);
1379 /* Merge the chains. */
1380 last = tsi_last (a->stmt_list);
1381 tsi_link_after (&last, b->stmt_list, TSI_NEW_STMT);
1382 b->stmt_list = NULL;
1386 /* Walk the function tree removing unnecessary statements.
1388 * Empty statement nodes are removed
1390 * Unnecessary TRY_FINALLY and TRY_CATCH blocks are removed
1392 * Unnecessary COND_EXPRs are removed
1394 * Some unnecessary BIND_EXPRs are removed
1396 Clearly more work could be done. The trick is doing the analysis
1397 and removal fast enough to be a net improvement in compile times.
1399 Note that when we remove a control structure such as a COND_EXPR
1400 BIND_EXPR, or TRY block, we will need to repeat this optimization pass
1401 to ensure we eliminate all the useless code. */
1403 struct rus_data
1405 tree *last_goto;
1406 bool repeat;
1407 bool may_throw;
1408 bool may_branch;
1409 bool has_label;
1412 static void remove_useless_stmts_1 (tree *, struct rus_data *);
1414 static bool
1415 remove_useless_stmts_warn_notreached (tree stmt)
1417 if (EXPR_HAS_LOCATION (stmt))
1419 location_t loc = EXPR_LOCATION (stmt);
1420 if (LOCATION_LINE (loc) > 0)
1422 warning (0, "%Hwill never be executed", &loc);
1423 return true;
1427 switch (TREE_CODE (stmt))
1429 case STATEMENT_LIST:
1431 tree_stmt_iterator i;
1432 for (i = tsi_start (stmt); !tsi_end_p (i); tsi_next (&i))
1433 if (remove_useless_stmts_warn_notreached (tsi_stmt (i)))
1434 return true;
1436 break;
1438 case COND_EXPR:
1439 if (remove_useless_stmts_warn_notreached (COND_EXPR_COND (stmt)))
1440 return true;
1441 if (remove_useless_stmts_warn_notreached (COND_EXPR_THEN (stmt)))
1442 return true;
1443 if (remove_useless_stmts_warn_notreached (COND_EXPR_ELSE (stmt)))
1444 return true;
1445 break;
1447 case TRY_FINALLY_EXPR:
1448 case TRY_CATCH_EXPR:
1449 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt, 0)))
1450 return true;
1451 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt, 1)))
1452 return true;
1453 break;
1455 case CATCH_EXPR:
1456 return remove_useless_stmts_warn_notreached (CATCH_BODY (stmt));
1457 case EH_FILTER_EXPR:
1458 return remove_useless_stmts_warn_notreached (EH_FILTER_FAILURE (stmt));
1459 case BIND_EXPR:
1460 return remove_useless_stmts_warn_notreached (BIND_EXPR_BLOCK (stmt));
1462 default:
1463 /* Not a live container. */
1464 break;
1467 return false;
1470 static void
1471 remove_useless_stmts_cond (tree *stmt_p, struct rus_data *data)
1473 tree then_clause, else_clause, cond;
1474 bool save_has_label, then_has_label, else_has_label;
1476 save_has_label = data->has_label;
1477 data->has_label = false;
1478 data->last_goto = NULL;
1480 remove_useless_stmts_1 (&COND_EXPR_THEN (*stmt_p), data);
1482 then_has_label = data->has_label;
1483 data->has_label = false;
1484 data->last_goto = NULL;
1486 remove_useless_stmts_1 (&COND_EXPR_ELSE (*stmt_p), data);
1488 else_has_label = data->has_label;
1489 data->has_label = save_has_label | then_has_label | else_has_label;
1491 then_clause = COND_EXPR_THEN (*stmt_p);
1492 else_clause = COND_EXPR_ELSE (*stmt_p);
1493 cond = fold (COND_EXPR_COND (*stmt_p));
1495 /* If neither arm does anything at all, we can remove the whole IF. */
1496 if (!TREE_SIDE_EFFECTS (then_clause) && !TREE_SIDE_EFFECTS (else_clause))
1498 *stmt_p = build_empty_stmt ();
1499 data->repeat = true;
1502 /* If there are no reachable statements in an arm, then we can
1503 zap the entire conditional. */
1504 else if (integer_nonzerop (cond) && !else_has_label)
1506 if (warn_notreached)
1507 remove_useless_stmts_warn_notreached (else_clause);
1508 *stmt_p = then_clause;
1509 data->repeat = true;
1511 else if (integer_zerop (cond) && !then_has_label)
1513 if (warn_notreached)
1514 remove_useless_stmts_warn_notreached (then_clause);
1515 *stmt_p = else_clause;
1516 data->repeat = true;
1519 /* Check a couple of simple things on then/else with single stmts. */
1520 else
1522 tree then_stmt = expr_only (then_clause);
1523 tree else_stmt = expr_only (else_clause);
1525 /* Notice branches to a common destination. */
1526 if (then_stmt && else_stmt
1527 && TREE_CODE (then_stmt) == GOTO_EXPR
1528 && TREE_CODE (else_stmt) == GOTO_EXPR
1529 && (GOTO_DESTINATION (then_stmt) == GOTO_DESTINATION (else_stmt)))
1531 *stmt_p = then_stmt;
1532 data->repeat = true;
1535 /* If the THEN/ELSE clause merely assigns a value to a variable or
1536 parameter which is already known to contain that value, then
1537 remove the useless THEN/ELSE clause. */
1538 else if (TREE_CODE (cond) == VAR_DECL || TREE_CODE (cond) == PARM_DECL)
1540 if (else_stmt
1541 && TREE_CODE (else_stmt) == MODIFY_EXPR
1542 && TREE_OPERAND (else_stmt, 0) == cond
1543 && integer_zerop (TREE_OPERAND (else_stmt, 1)))
1544 COND_EXPR_ELSE (*stmt_p) = alloc_stmt_list ();
1546 else if ((TREE_CODE (cond) == EQ_EXPR || TREE_CODE (cond) == NE_EXPR)
1547 && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL
1548 || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL)
1549 && TREE_CONSTANT (TREE_OPERAND (cond, 1)))
1551 tree stmt = (TREE_CODE (cond) == EQ_EXPR
1552 ? then_stmt : else_stmt);
1553 tree *location = (TREE_CODE (cond) == EQ_EXPR
1554 ? &COND_EXPR_THEN (*stmt_p)
1555 : &COND_EXPR_ELSE (*stmt_p));
1557 if (stmt
1558 && TREE_CODE (stmt) == MODIFY_EXPR
1559 && TREE_OPERAND (stmt, 0) == TREE_OPERAND (cond, 0)
1560 && TREE_OPERAND (stmt, 1) == TREE_OPERAND (cond, 1))
1561 *location = alloc_stmt_list ();
1565 /* Protect GOTOs in the arm of COND_EXPRs from being removed. They
1566 would be re-introduced during lowering. */
1567 data->last_goto = NULL;
1571 static void
1572 remove_useless_stmts_tf (tree *stmt_p, struct rus_data *data)
1574 bool save_may_branch, save_may_throw;
1575 bool this_may_branch, this_may_throw;
1577 /* Collect may_branch and may_throw information for the body only. */
1578 save_may_branch = data->may_branch;
1579 save_may_throw = data->may_throw;
1580 data->may_branch = false;
1581 data->may_throw = false;
1582 data->last_goto = NULL;
1584 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 0), data);
1586 this_may_branch = data->may_branch;
1587 this_may_throw = data->may_throw;
1588 data->may_branch |= save_may_branch;
1589 data->may_throw |= save_may_throw;
1590 data->last_goto = NULL;
1592 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 1), data);
1594 /* If the body is empty, then we can emit the FINALLY block without
1595 the enclosing TRY_FINALLY_EXPR. */
1596 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 0)))
1598 *stmt_p = TREE_OPERAND (*stmt_p, 1);
1599 data->repeat = true;
1602 /* If the handler is empty, then we can emit the TRY block without
1603 the enclosing TRY_FINALLY_EXPR. */
1604 else if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 1)))
1606 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1607 data->repeat = true;
1610 /* If the body neither throws, nor branches, then we can safely
1611 string the TRY and FINALLY blocks together. */
1612 else if (!this_may_branch && !this_may_throw)
1614 tree stmt = *stmt_p;
1615 *stmt_p = TREE_OPERAND (stmt, 0);
1616 append_to_statement_list (TREE_OPERAND (stmt, 1), stmt_p);
1617 data->repeat = true;
1622 static void
1623 remove_useless_stmts_tc (tree *stmt_p, struct rus_data *data)
1625 bool save_may_throw, this_may_throw;
1626 tree_stmt_iterator i;
1627 tree stmt;
1629 /* Collect may_throw information for the body only. */
1630 save_may_throw = data->may_throw;
1631 data->may_throw = false;
1632 data->last_goto = NULL;
1634 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 0), data);
1636 this_may_throw = data->may_throw;
1637 data->may_throw = save_may_throw;
1639 /* If the body cannot throw, then we can drop the entire TRY_CATCH_EXPR. */
1640 if (!this_may_throw)
1642 if (warn_notreached)
1643 remove_useless_stmts_warn_notreached (TREE_OPERAND (*stmt_p, 1));
1644 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1645 data->repeat = true;
1646 return;
1649 /* Process the catch clause specially. We may be able to tell that
1650 no exceptions propagate past this point. */
1652 this_may_throw = true;
1653 i = tsi_start (TREE_OPERAND (*stmt_p, 1));
1654 stmt = tsi_stmt (i);
1655 data->last_goto = NULL;
1657 switch (TREE_CODE (stmt))
1659 case CATCH_EXPR:
1660 for (; !tsi_end_p (i); tsi_next (&i))
1662 stmt = tsi_stmt (i);
1663 /* If we catch all exceptions, then the body does not
1664 propagate exceptions past this point. */
1665 if (CATCH_TYPES (stmt) == NULL)
1666 this_may_throw = false;
1667 data->last_goto = NULL;
1668 remove_useless_stmts_1 (&CATCH_BODY (stmt), data);
1670 break;
1672 case EH_FILTER_EXPR:
1673 if (EH_FILTER_MUST_NOT_THROW (stmt))
1674 this_may_throw = false;
1675 else if (EH_FILTER_TYPES (stmt) == NULL)
1676 this_may_throw = false;
1677 remove_useless_stmts_1 (&EH_FILTER_FAILURE (stmt), data);
1678 break;
1680 default:
1681 /* Otherwise this is a cleanup. */
1682 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 1), data);
1684 /* If the cleanup is empty, then we can emit the TRY block without
1685 the enclosing TRY_CATCH_EXPR. */
1686 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 1)))
1688 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1689 data->repeat = true;
1691 break;
1693 data->may_throw |= this_may_throw;
1697 static void
1698 remove_useless_stmts_bind (tree *stmt_p, struct rus_data *data)
1700 tree block;
1702 /* First remove anything underneath the BIND_EXPR. */
1703 remove_useless_stmts_1 (&BIND_EXPR_BODY (*stmt_p), data);
1705 /* If the BIND_EXPR has no variables, then we can pull everything
1706 up one level and remove the BIND_EXPR, unless this is the toplevel
1707 BIND_EXPR for the current function or an inlined function.
1709 When this situation occurs we will want to apply this
1710 optimization again. */
1711 block = BIND_EXPR_BLOCK (*stmt_p);
1712 if (BIND_EXPR_VARS (*stmt_p) == NULL_TREE
1713 && *stmt_p != DECL_SAVED_TREE (current_function_decl)
1714 && (! block
1715 || ! BLOCK_ABSTRACT_ORIGIN (block)
1716 || (TREE_CODE (BLOCK_ABSTRACT_ORIGIN (block))
1717 != FUNCTION_DECL)))
1719 *stmt_p = BIND_EXPR_BODY (*stmt_p);
1720 data->repeat = true;
1725 static void
1726 remove_useless_stmts_goto (tree *stmt_p, struct rus_data *data)
1728 tree dest = GOTO_DESTINATION (*stmt_p);
1730 data->may_branch = true;
1731 data->last_goto = NULL;
1733 /* Record the last goto expr, so that we can delete it if unnecessary. */
1734 if (TREE_CODE (dest) == LABEL_DECL)
1735 data->last_goto = stmt_p;
1739 static void
1740 remove_useless_stmts_label (tree *stmt_p, struct rus_data *data)
1742 tree label = LABEL_EXPR_LABEL (*stmt_p);
1744 data->has_label = true;
1746 /* We do want to jump across non-local label receiver code. */
1747 if (DECL_NONLOCAL (label))
1748 data->last_goto = NULL;
1750 else if (data->last_goto && GOTO_DESTINATION (*data->last_goto) == label)
1752 *data->last_goto = build_empty_stmt ();
1753 data->repeat = true;
1756 /* ??? Add something here to delete unused labels. */
1760 /* If the function is "const" or "pure", then clear TREE_SIDE_EFFECTS on its
1761 decl. This allows us to eliminate redundant or useless
1762 calls to "const" functions.
1764 Gimplifier already does the same operation, but we may notice functions
1765 being const and pure once their calls has been gimplified, so we need
1766 to update the flag. */
1768 static void
1769 update_call_expr_flags (tree call)
1771 tree decl = get_callee_fndecl (call);
1772 if (!decl)
1773 return;
1774 if (call_expr_flags (call) & (ECF_CONST | ECF_PURE))
1775 TREE_SIDE_EFFECTS (call) = 0;
1776 if (TREE_NOTHROW (decl))
1777 TREE_NOTHROW (call) = 1;
1781 /* T is CALL_EXPR. Set current_function_calls_* flags. */
1783 void
1784 notice_special_calls (tree t)
1786 int flags = call_expr_flags (t);
1788 if (flags & ECF_MAY_BE_ALLOCA)
1789 current_function_calls_alloca = true;
1790 if (flags & ECF_RETURNS_TWICE)
1791 current_function_calls_setjmp = true;
1795 /* Clear flags set by notice_special_calls. Used by dead code removal
1796 to update the flags. */
1798 void
1799 clear_special_calls (void)
1801 current_function_calls_alloca = false;
1802 current_function_calls_setjmp = false;
1806 static void
1807 remove_useless_stmts_1 (tree *tp, struct rus_data *data)
1809 tree t = *tp, op;
1811 switch (TREE_CODE (t))
1813 case COND_EXPR:
1814 remove_useless_stmts_cond (tp, data);
1815 break;
1817 case TRY_FINALLY_EXPR:
1818 remove_useless_stmts_tf (tp, data);
1819 break;
1821 case TRY_CATCH_EXPR:
1822 remove_useless_stmts_tc (tp, data);
1823 break;
1825 case BIND_EXPR:
1826 remove_useless_stmts_bind (tp, data);
1827 break;
1829 case GOTO_EXPR:
1830 remove_useless_stmts_goto (tp, data);
1831 break;
1833 case LABEL_EXPR:
1834 remove_useless_stmts_label (tp, data);
1835 break;
1837 case RETURN_EXPR:
1838 fold_stmt (tp);
1839 data->last_goto = NULL;
1840 data->may_branch = true;
1841 break;
1843 case CALL_EXPR:
1844 fold_stmt (tp);
1845 data->last_goto = NULL;
1846 notice_special_calls (t);
1847 update_call_expr_flags (t);
1848 if (tree_could_throw_p (t))
1849 data->may_throw = true;
1850 break;
1852 case MODIFY_EXPR:
1853 data->last_goto = NULL;
1854 fold_stmt (tp);
1855 op = get_call_expr_in (t);
1856 if (op)
1858 update_call_expr_flags (op);
1859 notice_special_calls (op);
1861 if (tree_could_throw_p (t))
1862 data->may_throw = true;
1863 break;
1865 case STATEMENT_LIST:
1867 tree_stmt_iterator i = tsi_start (t);
1868 while (!tsi_end_p (i))
1870 t = tsi_stmt (i);
1871 if (IS_EMPTY_STMT (t))
1873 tsi_delink (&i);
1874 continue;
1877 remove_useless_stmts_1 (tsi_stmt_ptr (i), data);
1879 t = tsi_stmt (i);
1880 if (TREE_CODE (t) == STATEMENT_LIST)
1882 tsi_link_before (&i, t, TSI_SAME_STMT);
1883 tsi_delink (&i);
1885 else
1886 tsi_next (&i);
1889 break;
1890 case ASM_EXPR:
1891 fold_stmt (tp);
1892 data->last_goto = NULL;
1893 break;
1895 default:
1896 data->last_goto = NULL;
1897 break;
1901 static void
1902 remove_useless_stmts (void)
1904 struct rus_data data;
1906 clear_special_calls ();
1910 memset (&data, 0, sizeof (data));
1911 remove_useless_stmts_1 (&DECL_SAVED_TREE (current_function_decl), &data);
1913 while (data.repeat);
1917 struct tree_opt_pass pass_remove_useless_stmts =
1919 "useless", /* name */
1920 NULL, /* gate */
1921 remove_useless_stmts, /* execute */
1922 NULL, /* sub */
1923 NULL, /* next */
1924 0, /* static_pass_number */
1925 0, /* tv_id */
1926 PROP_gimple_any, /* properties_required */
1927 0, /* properties_provided */
1928 0, /* properties_destroyed */
1929 0, /* todo_flags_start */
1930 TODO_dump_func, /* todo_flags_finish */
1931 0 /* letter */
1934 /* Remove PHI nodes associated with basic block BB and all edges out of BB. */
1936 static void
1937 remove_phi_nodes_and_edges_for_unreachable_block (basic_block bb)
1939 tree phi;
1941 /* Since this block is no longer reachable, we can just delete all
1942 of its PHI nodes. */
1943 phi = phi_nodes (bb);
1944 while (phi)
1946 tree next = PHI_CHAIN (phi);
1947 remove_phi_node (phi, NULL_TREE);
1948 phi = next;
1951 /* Remove edges to BB's successors. */
1952 while (EDGE_COUNT (bb->succs) > 0)
1953 remove_edge (EDGE_SUCC (bb, 0));
1957 /* Remove statements of basic block BB. */
1959 static void
1960 remove_bb (basic_block bb)
1962 block_stmt_iterator i;
1963 #ifdef USE_MAPPED_LOCATION
1964 source_location loc = UNKNOWN_LOCATION;
1965 #else
1966 source_locus loc = 0;
1967 #endif
1969 if (dump_file)
1971 fprintf (dump_file, "Removing basic block %d\n", bb->index);
1972 if (dump_flags & TDF_DETAILS)
1974 dump_bb (bb, dump_file, 0);
1975 fprintf (dump_file, "\n");
1979 /* If we remove the header or the latch of a loop, mark the loop for
1980 removal by setting its header and latch to NULL. */
1981 if (current_loops)
1983 struct loop *loop = bb->loop_father;
1985 if (loop->latch == bb
1986 || loop->header == bb)
1988 loop->latch = NULL;
1989 loop->header = NULL;
1993 /* Remove all the instructions in the block. */
1994 for (i = bsi_start (bb); !bsi_end_p (i);)
1996 tree stmt = bsi_stmt (i);
1997 if (TREE_CODE (stmt) == LABEL_EXPR
1998 && (FORCED_LABEL (LABEL_EXPR_LABEL (stmt))
1999 || DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt))))
2001 basic_block new_bb;
2002 block_stmt_iterator new_bsi;
2004 /* A non-reachable non-local label may still be referenced.
2005 But it no longer needs to carry the extra semantics of
2006 non-locality. */
2007 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)))
2009 DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)) = 0;
2010 FORCED_LABEL (LABEL_EXPR_LABEL (stmt)) = 1;
2013 new_bb = bb->prev_bb;
2014 new_bsi = bsi_start (new_bb);
2015 bsi_remove (&i);
2016 bsi_insert_before (&new_bsi, stmt, BSI_NEW_STMT);
2018 else
2020 /* Release SSA definitions if we are in SSA. Note that we
2021 may be called when not in SSA. For example,
2022 final_cleanup calls this function via
2023 cleanup_tree_cfg. */
2024 if (in_ssa_p)
2025 release_defs (stmt);
2027 bsi_remove (&i);
2030 /* Don't warn for removed gotos. Gotos are often removed due to
2031 jump threading, thus resulting in bogus warnings. Not great,
2032 since this way we lose warnings for gotos in the original
2033 program that are indeed unreachable. */
2034 if (TREE_CODE (stmt) != GOTO_EXPR && EXPR_HAS_LOCATION (stmt) && !loc)
2036 #ifdef USE_MAPPED_LOCATION
2037 if (EXPR_HAS_LOCATION (stmt))
2038 loc = EXPR_LOCATION (stmt);
2039 #else
2040 source_locus t;
2041 t = EXPR_LOCUS (stmt);
2042 if (t && LOCATION_LINE (*t) > 0)
2043 loc = t;
2044 #endif
2048 /* If requested, give a warning that the first statement in the
2049 block is unreachable. We walk statements backwards in the
2050 loop above, so the last statement we process is the first statement
2051 in the block. */
2052 #ifdef USE_MAPPED_LOCATION
2053 if (loc > BUILTINS_LOCATION)
2054 warning (OPT_Wunreachable_code, "%Hwill never be executed", &loc);
2055 #else
2056 if (loc)
2057 warning (OPT_Wunreachable_code, "%Hwill never be executed", loc);
2058 #endif
2060 remove_phi_nodes_and_edges_for_unreachable_block (bb);
2064 /* Given a basic block BB ending with COND_EXPR or SWITCH_EXPR, and a
2065 predicate VAL, return the edge that will be taken out of the block.
2066 If VAL does not match a unique edge, NULL is returned. */
2068 edge
2069 find_taken_edge (basic_block bb, tree val)
2071 tree stmt;
2073 stmt = last_stmt (bb);
2075 gcc_assert (stmt);
2076 gcc_assert (is_ctrl_stmt (stmt));
2077 gcc_assert (val);
2079 if (! is_gimple_min_invariant (val))
2080 return NULL;
2082 if (TREE_CODE (stmt) == COND_EXPR)
2083 return find_taken_edge_cond_expr (bb, val);
2085 if (TREE_CODE (stmt) == SWITCH_EXPR)
2086 return find_taken_edge_switch_expr (bb, val);
2088 if (computed_goto_p (stmt))
2089 return find_taken_edge_computed_goto (bb, TREE_OPERAND( val, 0));
2091 gcc_unreachable ();
2094 /* Given a constant value VAL and the entry block BB to a GOTO_EXPR
2095 statement, determine which of the outgoing edges will be taken out of the
2096 block. Return NULL if either edge may be taken. */
2098 static edge
2099 find_taken_edge_computed_goto (basic_block bb, tree val)
2101 basic_block dest;
2102 edge e = NULL;
2104 dest = label_to_block (val);
2105 if (dest)
2107 e = find_edge (bb, dest);
2108 gcc_assert (e != NULL);
2111 return e;
2114 /* Given a constant value VAL and the entry block BB to a COND_EXPR
2115 statement, determine which of the two edges will be taken out of the
2116 block. Return NULL if either edge may be taken. */
2118 static edge
2119 find_taken_edge_cond_expr (basic_block bb, tree val)
2121 edge true_edge, false_edge;
2123 extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
2125 gcc_assert (TREE_CODE (val) == INTEGER_CST);
2126 return (zero_p (val) ? false_edge : true_edge);
2129 /* Given an INTEGER_CST VAL and the entry block BB to a SWITCH_EXPR
2130 statement, determine which edge will be taken out of the block. Return
2131 NULL if any edge may be taken. */
2133 static edge
2134 find_taken_edge_switch_expr (basic_block bb, tree val)
2136 tree switch_expr, taken_case;
2137 basic_block dest_bb;
2138 edge e;
2140 switch_expr = last_stmt (bb);
2141 taken_case = find_case_label_for_value (switch_expr, val);
2142 dest_bb = label_to_block (CASE_LABEL (taken_case));
2144 e = find_edge (bb, dest_bb);
2145 gcc_assert (e);
2146 return e;
2150 /* Return the CASE_LABEL_EXPR that SWITCH_EXPR will take for VAL.
2151 We can make optimal use here of the fact that the case labels are
2152 sorted: We can do a binary search for a case matching VAL. */
2154 static tree
2155 find_case_label_for_value (tree switch_expr, tree val)
2157 tree vec = SWITCH_LABELS (switch_expr);
2158 size_t low, high, n = TREE_VEC_LENGTH (vec);
2159 tree default_case = TREE_VEC_ELT (vec, n - 1);
2161 for (low = -1, high = n - 1; high - low > 1; )
2163 size_t i = (high + low) / 2;
2164 tree t = TREE_VEC_ELT (vec, i);
2165 int cmp;
2167 /* Cache the result of comparing CASE_LOW and val. */
2168 cmp = tree_int_cst_compare (CASE_LOW (t), val);
2170 if (cmp > 0)
2171 high = i;
2172 else
2173 low = i;
2175 if (CASE_HIGH (t) == NULL)
2177 /* A singe-valued case label. */
2178 if (cmp == 0)
2179 return t;
2181 else
2183 /* A case range. We can only handle integer ranges. */
2184 if (cmp <= 0 && tree_int_cst_compare (CASE_HIGH (t), val) >= 0)
2185 return t;
2189 return default_case;
2195 /*---------------------------------------------------------------------------
2196 Debugging functions
2197 ---------------------------------------------------------------------------*/
2199 /* Dump tree-specific information of block BB to file OUTF. */
2201 void
2202 tree_dump_bb (basic_block bb, FILE *outf, int indent)
2204 dump_generic_bb (outf, bb, indent, TDF_VOPS);
2208 /* Dump a basic block on stderr. */
2210 void
2211 debug_tree_bb (basic_block bb)
2213 dump_bb (bb, stderr, 0);
2217 /* Dump basic block with index N on stderr. */
2219 basic_block
2220 debug_tree_bb_n (int n)
2222 debug_tree_bb (BASIC_BLOCK (n));
2223 return BASIC_BLOCK (n);
2227 /* Dump the CFG on stderr.
2229 FLAGS are the same used by the tree dumping functions
2230 (see TDF_* in tree.h). */
2232 void
2233 debug_tree_cfg (int flags)
2235 dump_tree_cfg (stderr, flags);
2239 /* Dump the program showing basic block boundaries on the given FILE.
2241 FLAGS are the same used by the tree dumping functions (see TDF_* in
2242 tree.h). */
2244 void
2245 dump_tree_cfg (FILE *file, int flags)
2247 if (flags & TDF_DETAILS)
2249 const char *funcname
2250 = lang_hooks.decl_printable_name (current_function_decl, 2);
2252 fputc ('\n', file);
2253 fprintf (file, ";; Function %s\n\n", funcname);
2254 fprintf (file, ";; \n%d basic blocks, %d edges, last basic block %d.\n\n",
2255 n_basic_blocks, n_edges, last_basic_block);
2257 brief_dump_cfg (file);
2258 fprintf (file, "\n");
2261 if (flags & TDF_STATS)
2262 dump_cfg_stats (file);
2264 dump_function_to_file (current_function_decl, file, flags | TDF_BLOCKS);
2268 /* Dump CFG statistics on FILE. */
2270 void
2271 dump_cfg_stats (FILE *file)
2273 static long max_num_merged_labels = 0;
2274 unsigned long size, total = 0;
2275 long num_edges;
2276 basic_block bb;
2277 const char * const fmt_str = "%-30s%-13s%12s\n";
2278 const char * const fmt_str_1 = "%-30s%13d%11lu%c\n";
2279 const char * const fmt_str_2 = "%-30s%13ld%11lu%c\n";
2280 const char * const fmt_str_3 = "%-43s%11lu%c\n";
2281 const char *funcname
2282 = lang_hooks.decl_printable_name (current_function_decl, 2);
2285 fprintf (file, "\nCFG Statistics for %s\n\n", funcname);
2287 fprintf (file, "---------------------------------------------------------\n");
2288 fprintf (file, fmt_str, "", " Number of ", "Memory");
2289 fprintf (file, fmt_str, "", " instances ", "used ");
2290 fprintf (file, "---------------------------------------------------------\n");
2292 size = n_basic_blocks * sizeof (struct basic_block_def);
2293 total += size;
2294 fprintf (file, fmt_str_1, "Basic blocks", n_basic_blocks,
2295 SCALE (size), LABEL (size));
2297 num_edges = 0;
2298 FOR_EACH_BB (bb)
2299 num_edges += EDGE_COUNT (bb->succs);
2300 size = num_edges * sizeof (struct edge_def);
2301 total += size;
2302 fprintf (file, fmt_str_2, "Edges", num_edges, SCALE (size), LABEL (size));
2304 fprintf (file, "---------------------------------------------------------\n");
2305 fprintf (file, fmt_str_3, "Total memory used by CFG data", SCALE (total),
2306 LABEL (total));
2307 fprintf (file, "---------------------------------------------------------\n");
2308 fprintf (file, "\n");
2310 if (cfg_stats.num_merged_labels > max_num_merged_labels)
2311 max_num_merged_labels = cfg_stats.num_merged_labels;
2313 fprintf (file, "Coalesced label blocks: %ld (Max so far: %ld)\n",
2314 cfg_stats.num_merged_labels, max_num_merged_labels);
2316 fprintf (file, "\n");
2320 /* Dump CFG statistics on stderr. Keep extern so that it's always
2321 linked in the final executable. */
2323 void
2324 debug_cfg_stats (void)
2326 dump_cfg_stats (stderr);
2330 /* Dump the flowgraph to a .vcg FILE. */
2332 static void
2333 tree_cfg2vcg (FILE *file)
2335 edge e;
2336 edge_iterator ei;
2337 basic_block bb;
2338 const char *funcname
2339 = lang_hooks.decl_printable_name (current_function_decl, 2);
2341 /* Write the file header. */
2342 fprintf (file, "graph: { title: \"%s\"\n", funcname);
2343 fprintf (file, "node: { title: \"ENTRY\" label: \"ENTRY\" }\n");
2344 fprintf (file, "node: { title: \"EXIT\" label: \"EXIT\" }\n");
2346 /* Write blocks and edges. */
2347 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
2349 fprintf (file, "edge: { sourcename: \"ENTRY\" targetname: \"%d\"",
2350 e->dest->index);
2352 if (e->flags & EDGE_FAKE)
2353 fprintf (file, " linestyle: dotted priority: 10");
2354 else
2355 fprintf (file, " linestyle: solid priority: 100");
2357 fprintf (file, " }\n");
2359 fputc ('\n', file);
2361 FOR_EACH_BB (bb)
2363 enum tree_code head_code, end_code;
2364 const char *head_name, *end_name;
2365 int head_line = 0;
2366 int end_line = 0;
2367 tree first = first_stmt (bb);
2368 tree last = last_stmt (bb);
2370 if (first)
2372 head_code = TREE_CODE (first);
2373 head_name = tree_code_name[head_code];
2374 head_line = get_lineno (first);
2376 else
2377 head_name = "no-statement";
2379 if (last)
2381 end_code = TREE_CODE (last);
2382 end_name = tree_code_name[end_code];
2383 end_line = get_lineno (last);
2385 else
2386 end_name = "no-statement";
2388 fprintf (file, "node: { title: \"%d\" label: \"#%d\\n%s (%d)\\n%s (%d)\"}\n",
2389 bb->index, bb->index, head_name, head_line, end_name,
2390 end_line);
2392 FOR_EACH_EDGE (e, ei, bb->succs)
2394 if (e->dest == EXIT_BLOCK_PTR)
2395 fprintf (file, "edge: { sourcename: \"%d\" targetname: \"EXIT\"", bb->index);
2396 else
2397 fprintf (file, "edge: { sourcename: \"%d\" targetname: \"%d\"", bb->index, e->dest->index);
2399 if (e->flags & EDGE_FAKE)
2400 fprintf (file, " priority: 10 linestyle: dotted");
2401 else
2402 fprintf (file, " priority: 100 linestyle: solid");
2404 fprintf (file, " }\n");
2407 if (bb->next_bb != EXIT_BLOCK_PTR)
2408 fputc ('\n', file);
2411 fputs ("}\n\n", file);
2416 /*---------------------------------------------------------------------------
2417 Miscellaneous helpers
2418 ---------------------------------------------------------------------------*/
2420 /* Return true if T represents a stmt that always transfers control. */
2422 bool
2423 is_ctrl_stmt (tree t)
2425 return (TREE_CODE (t) == COND_EXPR
2426 || TREE_CODE (t) == SWITCH_EXPR
2427 || TREE_CODE (t) == GOTO_EXPR
2428 || TREE_CODE (t) == RETURN_EXPR
2429 || TREE_CODE (t) == RESX_EXPR);
2433 /* Return true if T is a statement that may alter the flow of control
2434 (e.g., a call to a non-returning function). */
2436 bool
2437 is_ctrl_altering_stmt (tree t)
2439 tree call;
2441 gcc_assert (t);
2442 call = get_call_expr_in (t);
2443 if (call)
2445 /* A non-pure/const CALL_EXPR alters flow control if the current
2446 function has nonlocal labels. */
2447 if (TREE_SIDE_EFFECTS (call) && current_function_has_nonlocal_label)
2448 return true;
2450 /* A CALL_EXPR also alters control flow if it does not return. */
2451 if (call_expr_flags (call) & ECF_NORETURN)
2452 return true;
2455 /* If a statement can throw, it alters control flow. */
2456 return tree_can_throw_internal (t);
2460 /* Return true if T is a computed goto. */
2462 bool
2463 computed_goto_p (tree t)
2465 return (TREE_CODE (t) == GOTO_EXPR
2466 && TREE_CODE (GOTO_DESTINATION (t)) != LABEL_DECL);
2470 /* Checks whether EXPR is a simple local goto. */
2472 bool
2473 simple_goto_p (tree expr)
2475 return (TREE_CODE (expr) == GOTO_EXPR
2476 && TREE_CODE (GOTO_DESTINATION (expr)) == LABEL_DECL);
2480 /* Return true if T should start a new basic block. PREV_T is the
2481 statement preceding T. It is used when T is a label or a case label.
2482 Labels should only start a new basic block if their previous statement
2483 wasn't a label. Otherwise, sequence of labels would generate
2484 unnecessary basic blocks that only contain a single label. */
2486 static inline bool
2487 stmt_starts_bb_p (tree t, tree prev_t)
2489 if (t == NULL_TREE)
2490 return false;
2492 /* LABEL_EXPRs start a new basic block only if the preceding
2493 statement wasn't a label of the same type. This prevents the
2494 creation of consecutive blocks that have nothing but a single
2495 label. */
2496 if (TREE_CODE (t) == LABEL_EXPR)
2498 /* Nonlocal and computed GOTO targets always start a new block. */
2499 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (t))
2500 || FORCED_LABEL (LABEL_EXPR_LABEL (t)))
2501 return true;
2503 if (prev_t && TREE_CODE (prev_t) == LABEL_EXPR)
2505 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (prev_t)))
2506 return true;
2508 cfg_stats.num_merged_labels++;
2509 return false;
2511 else
2512 return true;
2515 return false;
2519 /* Return true if T should end a basic block. */
2521 bool
2522 stmt_ends_bb_p (tree t)
2524 return is_ctrl_stmt (t) || is_ctrl_altering_stmt (t);
2528 /* Add gotos that used to be represented implicitly in the CFG. */
2530 void
2531 disband_implicit_edges (void)
2533 basic_block bb;
2534 block_stmt_iterator last;
2535 edge e;
2536 edge_iterator ei;
2537 tree stmt, label;
2539 FOR_EACH_BB (bb)
2541 last = bsi_last (bb);
2542 stmt = last_stmt (bb);
2544 if (stmt && TREE_CODE (stmt) == COND_EXPR)
2546 /* Remove superfluous gotos from COND_EXPR branches. Moved
2547 from cfg_remove_useless_stmts here since it violates the
2548 invariants for tree--cfg correspondence and thus fits better
2549 here where we do it anyway. */
2550 e = find_edge (bb, bb->next_bb);
2551 if (e)
2553 if (e->flags & EDGE_TRUE_VALUE)
2554 COND_EXPR_THEN (stmt) = build_empty_stmt ();
2555 else if (e->flags & EDGE_FALSE_VALUE)
2556 COND_EXPR_ELSE (stmt) = build_empty_stmt ();
2557 else
2558 gcc_unreachable ();
2559 e->flags |= EDGE_FALLTHRU;
2562 continue;
2565 if (stmt && TREE_CODE (stmt) == RETURN_EXPR)
2567 /* Remove the RETURN_EXPR if we may fall though to the exit
2568 instead. */
2569 gcc_assert (single_succ_p (bb));
2570 gcc_assert (single_succ (bb) == EXIT_BLOCK_PTR);
2572 if (bb->next_bb == EXIT_BLOCK_PTR
2573 && !TREE_OPERAND (stmt, 0))
2575 bsi_remove (&last);
2576 single_succ_edge (bb)->flags |= EDGE_FALLTHRU;
2578 continue;
2581 /* There can be no fallthru edge if the last statement is a control
2582 one. */
2583 if (stmt && is_ctrl_stmt (stmt))
2584 continue;
2586 /* Find a fallthru edge and emit the goto if necessary. */
2587 FOR_EACH_EDGE (e, ei, bb->succs)
2588 if (e->flags & EDGE_FALLTHRU)
2589 break;
2591 if (!e || e->dest == bb->next_bb)
2592 continue;
2594 gcc_assert (e->dest != EXIT_BLOCK_PTR);
2595 label = tree_block_label (e->dest);
2597 stmt = build1 (GOTO_EXPR, void_type_node, label);
2598 #ifdef USE_MAPPED_LOCATION
2599 SET_EXPR_LOCATION (stmt, e->goto_locus);
2600 #else
2601 SET_EXPR_LOCUS (stmt, e->goto_locus);
2602 #endif
2603 bsi_insert_after (&last, stmt, BSI_NEW_STMT);
2604 e->flags &= ~EDGE_FALLTHRU;
2608 /* Remove block annotations and other datastructures. */
2610 void
2611 delete_tree_cfg_annotations (void)
2613 label_to_block_map = NULL;
2617 /* Return the first statement in basic block BB. */
2619 tree
2620 first_stmt (basic_block bb)
2622 block_stmt_iterator i = bsi_start (bb);
2623 return !bsi_end_p (i) ? bsi_stmt (i) : NULL_TREE;
2627 /* Return the last statement in basic block BB. */
2629 tree
2630 last_stmt (basic_block bb)
2632 block_stmt_iterator b = bsi_last (bb);
2633 return !bsi_end_p (b) ? bsi_stmt (b) : NULL_TREE;
2637 /* Return a pointer to the last statement in block BB. */
2639 tree *
2640 last_stmt_ptr (basic_block bb)
2642 block_stmt_iterator last = bsi_last (bb);
2643 return !bsi_end_p (last) ? bsi_stmt_ptr (last) : NULL;
2647 /* Return the last statement of an otherwise empty block. Return NULL
2648 if the block is totally empty, or if it contains more than one
2649 statement. */
2651 tree
2652 last_and_only_stmt (basic_block bb)
2654 block_stmt_iterator i = bsi_last (bb);
2655 tree last, prev;
2657 if (bsi_end_p (i))
2658 return NULL_TREE;
2660 last = bsi_stmt (i);
2661 bsi_prev (&i);
2662 if (bsi_end_p (i))
2663 return last;
2665 /* Empty statements should no longer appear in the instruction stream.
2666 Everything that might have appeared before should be deleted by
2667 remove_useless_stmts, and the optimizers should just bsi_remove
2668 instead of smashing with build_empty_stmt.
2670 Thus the only thing that should appear here in a block containing
2671 one executable statement is a label. */
2672 prev = bsi_stmt (i);
2673 if (TREE_CODE (prev) == LABEL_EXPR)
2674 return last;
2675 else
2676 return NULL_TREE;
2680 /* Mark BB as the basic block holding statement T. */
2682 void
2683 set_bb_for_stmt (tree t, basic_block bb)
2685 if (TREE_CODE (t) == PHI_NODE)
2686 PHI_BB (t) = bb;
2687 else if (TREE_CODE (t) == STATEMENT_LIST)
2689 tree_stmt_iterator i;
2690 for (i = tsi_start (t); !tsi_end_p (i); tsi_next (&i))
2691 set_bb_for_stmt (tsi_stmt (i), bb);
2693 else
2695 stmt_ann_t ann = get_stmt_ann (t);
2696 ann->bb = bb;
2698 /* If the statement is a label, add the label to block-to-labels map
2699 so that we can speed up edge creation for GOTO_EXPRs. */
2700 if (TREE_CODE (t) == LABEL_EXPR)
2702 int uid;
2704 t = LABEL_EXPR_LABEL (t);
2705 uid = LABEL_DECL_UID (t);
2706 if (uid == -1)
2708 LABEL_DECL_UID (t) = uid = cfun->last_label_uid++;
2709 if (VARRAY_SIZE (label_to_block_map) <= (unsigned) uid)
2710 VARRAY_GROW (label_to_block_map, 3 * uid / 2);
2712 else
2713 /* We're moving an existing label. Make sure that we've
2714 removed it from the old block. */
2715 gcc_assert (!bb || !VARRAY_BB (label_to_block_map, uid));
2716 VARRAY_BB (label_to_block_map, uid) = bb;
2721 /* Finds iterator for STMT. */
2723 extern block_stmt_iterator
2724 bsi_for_stmt (tree stmt)
2726 block_stmt_iterator bsi;
2728 for (bsi = bsi_start (bb_for_stmt (stmt)); !bsi_end_p (bsi); bsi_next (&bsi))
2729 if (bsi_stmt (bsi) == stmt)
2730 return bsi;
2732 gcc_unreachable ();
2735 /* Mark statement T as modified, and update it. */
2736 static inline void
2737 update_modified_stmts (tree t)
2739 if (TREE_CODE (t) == STATEMENT_LIST)
2741 tree_stmt_iterator i;
2742 tree stmt;
2743 for (i = tsi_start (t); !tsi_end_p (i); tsi_next (&i))
2745 stmt = tsi_stmt (i);
2746 update_stmt_if_modified (stmt);
2749 else
2750 update_stmt_if_modified (t);
2753 /* Insert statement (or statement list) T before the statement
2754 pointed-to by iterator I. M specifies how to update iterator I
2755 after insertion (see enum bsi_iterator_update). */
2757 void
2758 bsi_insert_before (block_stmt_iterator *i, tree t, enum bsi_iterator_update m)
2760 set_bb_for_stmt (t, i->bb);
2761 update_modified_stmts (t);
2762 tsi_link_before (&i->tsi, t, m);
2766 /* Insert statement (or statement list) T after the statement
2767 pointed-to by iterator I. M specifies how to update iterator I
2768 after insertion (see enum bsi_iterator_update). */
2770 void
2771 bsi_insert_after (block_stmt_iterator *i, tree t, enum bsi_iterator_update m)
2773 set_bb_for_stmt (t, i->bb);
2774 update_modified_stmts (t);
2775 tsi_link_after (&i->tsi, t, m);
2779 /* Remove the statement pointed to by iterator I. The iterator is updated
2780 to the next statement. */
2782 void
2783 bsi_remove (block_stmt_iterator *i)
2785 tree t = bsi_stmt (*i);
2786 set_bb_for_stmt (t, NULL);
2787 delink_stmt_imm_use (t);
2788 tsi_delink (&i->tsi);
2789 mark_stmt_modified (t);
2793 /* Move the statement at FROM so it comes right after the statement at TO. */
2795 void
2796 bsi_move_after (block_stmt_iterator *from, block_stmt_iterator *to)
2798 tree stmt = bsi_stmt (*from);
2799 bsi_remove (from);
2800 bsi_insert_after (to, stmt, BSI_SAME_STMT);
2804 /* Move the statement at FROM so it comes right before the statement at TO. */
2806 void
2807 bsi_move_before (block_stmt_iterator *from, block_stmt_iterator *to)
2809 tree stmt = bsi_stmt (*from);
2810 bsi_remove (from);
2811 bsi_insert_before (to, stmt, BSI_SAME_STMT);
2815 /* Move the statement at FROM to the end of basic block BB. */
2817 void
2818 bsi_move_to_bb_end (block_stmt_iterator *from, basic_block bb)
2820 block_stmt_iterator last = bsi_last (bb);
2822 /* Have to check bsi_end_p because it could be an empty block. */
2823 if (!bsi_end_p (last) && is_ctrl_stmt (bsi_stmt (last)))
2824 bsi_move_before (from, &last);
2825 else
2826 bsi_move_after (from, &last);
2830 /* Replace the contents of the statement pointed to by iterator BSI
2831 with STMT. If PRESERVE_EH_INFO is true, the exception handling
2832 information of the original statement is preserved. */
2834 void
2835 bsi_replace (const block_stmt_iterator *bsi, tree stmt, bool preserve_eh_info)
2837 int eh_region;
2838 tree orig_stmt = bsi_stmt (*bsi);
2840 SET_EXPR_LOCUS (stmt, EXPR_LOCUS (orig_stmt));
2841 set_bb_for_stmt (stmt, bsi->bb);
2843 /* Preserve EH region information from the original statement, if
2844 requested by the caller. */
2845 if (preserve_eh_info)
2847 eh_region = lookup_stmt_eh_region (orig_stmt);
2848 if (eh_region >= 0)
2849 add_stmt_to_eh_region (stmt, eh_region);
2852 delink_stmt_imm_use (orig_stmt);
2853 *bsi_stmt_ptr (*bsi) = stmt;
2854 mark_stmt_modified (stmt);
2855 update_modified_stmts (stmt);
2859 /* Insert the statement pointed-to by BSI into edge E. Every attempt
2860 is made to place the statement in an existing basic block, but
2861 sometimes that isn't possible. When it isn't possible, the edge is
2862 split and the statement is added to the new block.
2864 In all cases, the returned *BSI points to the correct location. The
2865 return value is true if insertion should be done after the location,
2866 or false if it should be done before the location. If new basic block
2867 has to be created, it is stored in *NEW_BB. */
2869 static bool
2870 tree_find_edge_insert_loc (edge e, block_stmt_iterator *bsi,
2871 basic_block *new_bb)
2873 basic_block dest, src;
2874 tree tmp;
2876 dest = e->dest;
2877 restart:
2879 /* If the destination has one predecessor which has no PHI nodes,
2880 insert there. Except for the exit block.
2882 The requirement for no PHI nodes could be relaxed. Basically we
2883 would have to examine the PHIs to prove that none of them used
2884 the value set by the statement we want to insert on E. That
2885 hardly seems worth the effort. */
2886 if (single_pred_p (dest)
2887 && ! phi_nodes (dest)
2888 && dest != EXIT_BLOCK_PTR)
2890 *bsi = bsi_start (dest);
2891 if (bsi_end_p (*bsi))
2892 return true;
2894 /* Make sure we insert after any leading labels. */
2895 tmp = bsi_stmt (*bsi);
2896 while (TREE_CODE (tmp) == LABEL_EXPR)
2898 bsi_next (bsi);
2899 if (bsi_end_p (*bsi))
2900 break;
2901 tmp = bsi_stmt (*bsi);
2904 if (bsi_end_p (*bsi))
2906 *bsi = bsi_last (dest);
2907 return true;
2909 else
2910 return false;
2913 /* If the source has one successor, the edge is not abnormal and
2914 the last statement does not end a basic block, insert there.
2915 Except for the entry block. */
2916 src = e->src;
2917 if ((e->flags & EDGE_ABNORMAL) == 0
2918 && single_succ_p (src)
2919 && src != ENTRY_BLOCK_PTR)
2921 *bsi = bsi_last (src);
2922 if (bsi_end_p (*bsi))
2923 return true;
2925 tmp = bsi_stmt (*bsi);
2926 if (!stmt_ends_bb_p (tmp))
2927 return true;
2929 /* Insert code just before returning the value. We may need to decompose
2930 the return in the case it contains non-trivial operand. */
2931 if (TREE_CODE (tmp) == RETURN_EXPR)
2933 tree op = TREE_OPERAND (tmp, 0);
2934 if (!is_gimple_val (op))
2936 gcc_assert (TREE_CODE (op) == MODIFY_EXPR);
2937 bsi_insert_before (bsi, op, BSI_NEW_STMT);
2938 TREE_OPERAND (tmp, 0) = TREE_OPERAND (op, 0);
2940 bsi_prev (bsi);
2941 return true;
2945 /* Otherwise, create a new basic block, and split this edge. */
2946 dest = split_edge (e);
2947 if (new_bb)
2948 *new_bb = dest;
2949 e = single_pred_edge (dest);
2950 goto restart;
2954 /* This routine will commit all pending edge insertions, creating any new
2955 basic blocks which are necessary. */
2957 void
2958 bsi_commit_edge_inserts (void)
2960 basic_block bb;
2961 edge e;
2962 edge_iterator ei;
2964 bsi_commit_one_edge_insert (single_succ_edge (ENTRY_BLOCK_PTR), NULL);
2966 FOR_EACH_BB (bb)
2967 FOR_EACH_EDGE (e, ei, bb->succs)
2968 bsi_commit_one_edge_insert (e, NULL);
2972 /* Commit insertions pending at edge E. If a new block is created, set NEW_BB
2973 to this block, otherwise set it to NULL. */
2975 void
2976 bsi_commit_one_edge_insert (edge e, basic_block *new_bb)
2978 if (new_bb)
2979 *new_bb = NULL;
2980 if (PENDING_STMT (e))
2982 block_stmt_iterator bsi;
2983 tree stmt = PENDING_STMT (e);
2985 PENDING_STMT (e) = NULL_TREE;
2987 if (tree_find_edge_insert_loc (e, &bsi, new_bb))
2988 bsi_insert_after (&bsi, stmt, BSI_NEW_STMT);
2989 else
2990 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
2995 /* Add STMT to the pending list of edge E. No actual insertion is
2996 made until a call to bsi_commit_edge_inserts () is made. */
2998 void
2999 bsi_insert_on_edge (edge e, tree stmt)
3001 append_to_statement_list (stmt, &PENDING_STMT (e));
3004 /* Similar to bsi_insert_on_edge+bsi_commit_edge_inserts. If a new
3005 block has to be created, it is returned. */
3007 basic_block
3008 bsi_insert_on_edge_immediate (edge e, tree stmt)
3010 block_stmt_iterator bsi;
3011 basic_block new_bb = NULL;
3013 gcc_assert (!PENDING_STMT (e));
3015 if (tree_find_edge_insert_loc (e, &bsi, &new_bb))
3016 bsi_insert_after (&bsi, stmt, BSI_NEW_STMT);
3017 else
3018 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
3020 return new_bb;
3023 /*---------------------------------------------------------------------------
3024 Tree specific functions for CFG manipulation
3025 ---------------------------------------------------------------------------*/
3027 /* Reinstall those PHI arguments queued in OLD_EDGE to NEW_EDGE. */
3029 static void
3030 reinstall_phi_args (edge new_edge, edge old_edge)
3032 tree var, phi;
3034 if (!PENDING_STMT (old_edge))
3035 return;
3037 for (var = PENDING_STMT (old_edge), phi = phi_nodes (new_edge->dest);
3038 var && phi;
3039 var = TREE_CHAIN (var), phi = PHI_CHAIN (phi))
3041 tree result = TREE_PURPOSE (var);
3042 tree arg = TREE_VALUE (var);
3044 gcc_assert (result == PHI_RESULT (phi));
3046 add_phi_arg (phi, arg, new_edge);
3049 PENDING_STMT (old_edge) = NULL;
3052 /* Returns the basic block after that the new basic block created
3053 by splitting edge EDGE_IN should be placed. Tries to keep the new block
3054 near its "logical" location. This is of most help to humans looking
3055 at debugging dumps. */
3057 static basic_block
3058 split_edge_bb_loc (edge edge_in)
3060 basic_block dest = edge_in->dest;
3062 if (dest->prev_bb && find_edge (dest->prev_bb, dest))
3063 return edge_in->src;
3064 else
3065 return dest->prev_bb;
3068 /* Split a (typically critical) edge EDGE_IN. Return the new block.
3069 Abort on abnormal edges. */
3071 static basic_block
3072 tree_split_edge (edge edge_in)
3074 basic_block new_bb, after_bb, dest, src;
3075 edge new_edge, e;
3077 /* Abnormal edges cannot be split. */
3078 gcc_assert (!(edge_in->flags & EDGE_ABNORMAL));
3080 src = edge_in->src;
3081 dest = edge_in->dest;
3083 after_bb = split_edge_bb_loc (edge_in);
3085 new_bb = create_empty_bb (after_bb);
3086 new_bb->frequency = EDGE_FREQUENCY (edge_in);
3087 new_bb->count = edge_in->count;
3088 new_edge = make_edge (new_bb, dest, EDGE_FALLTHRU);
3089 new_edge->probability = REG_BR_PROB_BASE;
3090 new_edge->count = edge_in->count;
3092 e = redirect_edge_and_branch (edge_in, new_bb);
3093 gcc_assert (e);
3094 reinstall_phi_args (new_edge, e);
3096 return new_bb;
3100 /* Return true when BB has label LABEL in it. */
3102 static bool
3103 has_label_p (basic_block bb, tree label)
3105 block_stmt_iterator bsi;
3107 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3109 tree stmt = bsi_stmt (bsi);
3111 if (TREE_CODE (stmt) != LABEL_EXPR)
3112 return false;
3113 if (LABEL_EXPR_LABEL (stmt) == label)
3114 return true;
3116 return false;
3120 /* Callback for walk_tree, check that all elements with address taken are
3121 properly noticed as such. The DATA is an int* that is 1 if TP was seen
3122 inside a PHI node. */
3124 static tree
3125 verify_expr (tree *tp, int *walk_subtrees, void *data ATTRIBUTE_UNUSED)
3127 tree t = *tp, x;
3128 bool in_phi = (data != NULL);
3130 if (TYPE_P (t))
3131 *walk_subtrees = 0;
3133 /* Check operand N for being valid GIMPLE and give error MSG if not. */
3134 #define CHECK_OP(N, MSG) \
3135 do { if (!is_gimple_val (TREE_OPERAND (t, N))) \
3136 { error (MSG); return TREE_OPERAND (t, N); }} while (0)
3138 switch (TREE_CODE (t))
3140 case SSA_NAME:
3141 if (SSA_NAME_IN_FREE_LIST (t))
3143 error ("SSA name in freelist but still referenced");
3144 return *tp;
3146 break;
3148 case ASSERT_EXPR:
3149 x = fold (ASSERT_EXPR_COND (t));
3150 if (x == boolean_false_node)
3152 error ("ASSERT_EXPR with an always-false condition");
3153 return *tp;
3155 break;
3157 case MODIFY_EXPR:
3158 x = TREE_OPERAND (t, 0);
3159 if (TREE_CODE (x) == BIT_FIELD_REF
3160 && is_gimple_reg (TREE_OPERAND (x, 0)))
3162 error ("GIMPLE register modified with BIT_FIELD_REF");
3163 return t;
3165 break;
3167 case ADDR_EXPR:
3169 bool old_invariant;
3170 bool old_constant;
3171 bool old_side_effects;
3172 bool new_invariant;
3173 bool new_constant;
3174 bool new_side_effects;
3176 /* ??? tree-ssa-alias.c may have overlooked dead PHI nodes, missing
3177 dead PHIs that take the address of something. But if the PHI
3178 result is dead, the fact that it takes the address of anything
3179 is irrelevant. Because we can not tell from here if a PHI result
3180 is dead, we just skip this check for PHIs altogether. This means
3181 we may be missing "valid" checks, but what can you do?
3182 This was PR19217. */
3183 if (in_phi)
3184 break;
3186 old_invariant = TREE_INVARIANT (t);
3187 old_constant = TREE_CONSTANT (t);
3188 old_side_effects = TREE_SIDE_EFFECTS (t);
3190 recompute_tree_invarant_for_addr_expr (t);
3191 new_invariant = TREE_INVARIANT (t);
3192 new_side_effects = TREE_SIDE_EFFECTS (t);
3193 new_constant = TREE_CONSTANT (t);
3195 if (old_invariant != new_invariant)
3197 error ("invariant not recomputed when ADDR_EXPR changed");
3198 return t;
3201 if (old_constant != new_constant)
3203 error ("constant not recomputed when ADDR_EXPR changed");
3204 return t;
3206 if (old_side_effects != new_side_effects)
3208 error ("side effects not recomputed when ADDR_EXPR changed");
3209 return t;
3212 /* Skip any references (they will be checked when we recurse down the
3213 tree) and ensure that any variable used as a prefix is marked
3214 addressable. */
3215 for (x = TREE_OPERAND (t, 0);
3216 handled_component_p (x);
3217 x = TREE_OPERAND (x, 0))
3220 if (TREE_CODE (x) != VAR_DECL && TREE_CODE (x) != PARM_DECL)
3221 return NULL;
3222 if (!TREE_ADDRESSABLE (x))
3224 error ("address taken, but ADDRESSABLE bit not set");
3225 return x;
3227 break;
3230 case COND_EXPR:
3231 x = COND_EXPR_COND (t);
3232 if (TREE_CODE (TREE_TYPE (x)) != BOOLEAN_TYPE)
3234 error ("non-boolean used in condition");
3235 return x;
3237 if (!is_gimple_condexpr (x))
3239 error ("invalid conditional operand");
3240 return x;
3242 break;
3244 case NOP_EXPR:
3245 case CONVERT_EXPR:
3246 case FIX_TRUNC_EXPR:
3247 case FIX_CEIL_EXPR:
3248 case FIX_FLOOR_EXPR:
3249 case FIX_ROUND_EXPR:
3250 case FLOAT_EXPR:
3251 case NEGATE_EXPR:
3252 case ABS_EXPR:
3253 case BIT_NOT_EXPR:
3254 case NON_LVALUE_EXPR:
3255 case TRUTH_NOT_EXPR:
3256 CHECK_OP (0, "invalid operand to unary operator");
3257 break;
3259 case REALPART_EXPR:
3260 case IMAGPART_EXPR:
3261 case COMPONENT_REF:
3262 case ARRAY_REF:
3263 case ARRAY_RANGE_REF:
3264 case BIT_FIELD_REF:
3265 case VIEW_CONVERT_EXPR:
3266 /* We have a nest of references. Verify that each of the operands
3267 that determine where to reference is either a constant or a variable,
3268 verify that the base is valid, and then show we've already checked
3269 the subtrees. */
3270 while (handled_component_p (t))
3272 if (TREE_CODE (t) == COMPONENT_REF && TREE_OPERAND (t, 2))
3273 CHECK_OP (2, "invalid COMPONENT_REF offset operator");
3274 else if (TREE_CODE (t) == ARRAY_REF
3275 || TREE_CODE (t) == ARRAY_RANGE_REF)
3277 CHECK_OP (1, "invalid array index");
3278 if (TREE_OPERAND (t, 2))
3279 CHECK_OP (2, "invalid array lower bound");
3280 if (TREE_OPERAND (t, 3))
3281 CHECK_OP (3, "invalid array stride");
3283 else if (TREE_CODE (t) == BIT_FIELD_REF)
3285 CHECK_OP (1, "invalid operand to BIT_FIELD_REF");
3286 CHECK_OP (2, "invalid operand to BIT_FIELD_REF");
3289 t = TREE_OPERAND (t, 0);
3292 if (!CONSTANT_CLASS_P (t) && !is_gimple_lvalue (t))
3294 error ("invalid reference prefix");
3295 return t;
3297 *walk_subtrees = 0;
3298 break;
3300 case LT_EXPR:
3301 case LE_EXPR:
3302 case GT_EXPR:
3303 case GE_EXPR:
3304 case EQ_EXPR:
3305 case NE_EXPR:
3306 case UNORDERED_EXPR:
3307 case ORDERED_EXPR:
3308 case UNLT_EXPR:
3309 case UNLE_EXPR:
3310 case UNGT_EXPR:
3311 case UNGE_EXPR:
3312 case UNEQ_EXPR:
3313 case LTGT_EXPR:
3314 case PLUS_EXPR:
3315 case MINUS_EXPR:
3316 case MULT_EXPR:
3317 case TRUNC_DIV_EXPR:
3318 case CEIL_DIV_EXPR:
3319 case FLOOR_DIV_EXPR:
3320 case ROUND_DIV_EXPR:
3321 case TRUNC_MOD_EXPR:
3322 case CEIL_MOD_EXPR:
3323 case FLOOR_MOD_EXPR:
3324 case ROUND_MOD_EXPR:
3325 case RDIV_EXPR:
3326 case EXACT_DIV_EXPR:
3327 case MIN_EXPR:
3328 case MAX_EXPR:
3329 case LSHIFT_EXPR:
3330 case RSHIFT_EXPR:
3331 case LROTATE_EXPR:
3332 case RROTATE_EXPR:
3333 case BIT_IOR_EXPR:
3334 case BIT_XOR_EXPR:
3335 case BIT_AND_EXPR:
3336 CHECK_OP (0, "invalid operand to binary operator");
3337 CHECK_OP (1, "invalid operand to binary operator");
3338 break;
3340 default:
3341 break;
3343 return NULL;
3345 #undef CHECK_OP
3349 /* Verify STMT, return true if STMT is not in GIMPLE form.
3350 TODO: Implement type checking. */
3352 static bool
3353 verify_stmt (tree stmt, bool last_in_block)
3355 tree addr;
3357 if (!is_gimple_stmt (stmt))
3359 error ("is not a valid GIMPLE statement");
3360 goto fail;
3363 addr = walk_tree (&stmt, verify_expr, NULL, NULL);
3364 if (addr)
3366 debug_generic_stmt (addr);
3367 return true;
3370 /* If the statement is marked as part of an EH region, then it is
3371 expected that the statement could throw. Verify that when we
3372 have optimizations that simplify statements such that we prove
3373 that they cannot throw, that we update other data structures
3374 to match. */
3375 if (lookup_stmt_eh_region (stmt) >= 0)
3377 if (!tree_could_throw_p (stmt))
3379 error ("statement marked for throw, but doesn%'t");
3380 goto fail;
3382 if (!last_in_block && tree_can_throw_internal (stmt))
3384 error ("statement marked for throw in middle of block");
3385 goto fail;
3389 return false;
3391 fail:
3392 debug_generic_stmt (stmt);
3393 return true;
3397 /* Return true when the T can be shared. */
3399 static bool
3400 tree_node_can_be_shared (tree t)
3402 if (IS_TYPE_OR_DECL_P (t)
3403 /* We check for constants explicitly since they are not considered
3404 gimple invariants if they overflowed. */
3405 || CONSTANT_CLASS_P (t)
3406 || is_gimple_min_invariant (t)
3407 || TREE_CODE (t) == SSA_NAME
3408 || t == error_mark_node)
3409 return true;
3411 if (TREE_CODE (t) == CASE_LABEL_EXPR)
3412 return true;
3414 while (((TREE_CODE (t) == ARRAY_REF || TREE_CODE (t) == ARRAY_RANGE_REF)
3415 /* We check for constants explicitly since they are not considered
3416 gimple invariants if they overflowed. */
3417 && (CONSTANT_CLASS_P (TREE_OPERAND (t, 1))
3418 || is_gimple_min_invariant (TREE_OPERAND (t, 1))))
3419 || (TREE_CODE (t) == COMPONENT_REF
3420 || TREE_CODE (t) == REALPART_EXPR
3421 || TREE_CODE (t) == IMAGPART_EXPR))
3422 t = TREE_OPERAND (t, 0);
3424 if (DECL_P (t))
3425 return true;
3427 return false;
3431 /* Called via walk_trees. Verify tree sharing. */
3433 static tree
3434 verify_node_sharing (tree * tp, int *walk_subtrees, void *data)
3436 htab_t htab = (htab_t) data;
3437 void **slot;
3439 if (tree_node_can_be_shared (*tp))
3441 *walk_subtrees = false;
3442 return NULL;
3445 slot = htab_find_slot (htab, *tp, INSERT);
3446 if (*slot)
3447 return *slot;
3448 *slot = *tp;
3450 return NULL;
3454 /* Verify the GIMPLE statement chain. */
3456 void
3457 verify_stmts (void)
3459 basic_block bb;
3460 block_stmt_iterator bsi;
3461 bool err = false;
3462 htab_t htab;
3463 tree addr;
3465 timevar_push (TV_TREE_STMT_VERIFY);
3466 htab = htab_create (37, htab_hash_pointer, htab_eq_pointer, NULL);
3468 FOR_EACH_BB (bb)
3470 tree phi;
3471 int i;
3473 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
3475 int phi_num_args = PHI_NUM_ARGS (phi);
3477 if (bb_for_stmt (phi) != bb)
3479 error ("bb_for_stmt (phi) is set to a wrong basic block");
3480 err |= true;
3483 for (i = 0; i < phi_num_args; i++)
3485 tree t = PHI_ARG_DEF (phi, i);
3486 tree addr;
3488 /* Addressable variables do have SSA_NAMEs but they
3489 are not considered gimple values. */
3490 if (TREE_CODE (t) != SSA_NAME
3491 && TREE_CODE (t) != FUNCTION_DECL
3492 && !is_gimple_val (t))
3494 error ("PHI def is not a GIMPLE value");
3495 debug_generic_stmt (phi);
3496 debug_generic_stmt (t);
3497 err |= true;
3500 addr = walk_tree (&t, verify_expr, (void *) 1, NULL);
3501 if (addr)
3503 debug_generic_stmt (addr);
3504 err |= true;
3507 addr = walk_tree (&t, verify_node_sharing, htab, NULL);
3508 if (addr)
3510 error ("incorrect sharing of tree nodes");
3511 debug_generic_stmt (phi);
3512 debug_generic_stmt (addr);
3513 err |= true;
3518 for (bsi = bsi_start (bb); !bsi_end_p (bsi); )
3520 tree stmt = bsi_stmt (bsi);
3522 if (bb_for_stmt (stmt) != bb)
3524 error ("bb_for_stmt (stmt) is set to a wrong basic block");
3525 err |= true;
3528 bsi_next (&bsi);
3529 err |= verify_stmt (stmt, bsi_end_p (bsi));
3530 addr = walk_tree (&stmt, verify_node_sharing, htab, NULL);
3531 if (addr)
3533 error ("incorrect sharing of tree nodes");
3534 debug_generic_stmt (stmt);
3535 debug_generic_stmt (addr);
3536 err |= true;
3541 if (err)
3542 internal_error ("verify_stmts failed");
3544 htab_delete (htab);
3545 timevar_pop (TV_TREE_STMT_VERIFY);
3549 /* Verifies that the flow information is OK. */
3551 static int
3552 tree_verify_flow_info (void)
3554 int err = 0;
3555 basic_block bb;
3556 block_stmt_iterator bsi;
3557 tree stmt;
3558 edge e;
3559 edge_iterator ei;
3561 if (ENTRY_BLOCK_PTR->stmt_list)
3563 error ("ENTRY_BLOCK has a statement list associated with it");
3564 err = 1;
3567 if (EXIT_BLOCK_PTR->stmt_list)
3569 error ("EXIT_BLOCK has a statement list associated with it");
3570 err = 1;
3573 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
3574 if (e->flags & EDGE_FALLTHRU)
3576 error ("fallthru to exit from bb %d", e->src->index);
3577 err = 1;
3580 FOR_EACH_BB (bb)
3582 bool found_ctrl_stmt = false;
3584 stmt = NULL_TREE;
3586 /* Skip labels on the start of basic block. */
3587 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3589 tree prev_stmt = stmt;
3591 stmt = bsi_stmt (bsi);
3593 if (TREE_CODE (stmt) != LABEL_EXPR)
3594 break;
3596 if (prev_stmt && DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)))
3598 error ("nonlocal label %s is not first "
3599 "in a sequence of labels in bb %d",
3600 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt))),
3601 bb->index);
3602 err = 1;
3605 if (label_to_block (LABEL_EXPR_LABEL (stmt)) != bb)
3607 error ("label %s to block does not match in bb %d",
3608 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt))),
3609 bb->index);
3610 err = 1;
3613 if (decl_function_context (LABEL_EXPR_LABEL (stmt))
3614 != current_function_decl)
3616 error ("label %s has incorrect context in bb %d",
3617 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt))),
3618 bb->index);
3619 err = 1;
3623 /* Verify that body of basic block BB is free of control flow. */
3624 for (; !bsi_end_p (bsi); bsi_next (&bsi))
3626 tree stmt = bsi_stmt (bsi);
3628 if (found_ctrl_stmt)
3630 error ("control flow in the middle of basic block %d",
3631 bb->index);
3632 err = 1;
3635 if (stmt_ends_bb_p (stmt))
3636 found_ctrl_stmt = true;
3638 if (TREE_CODE (stmt) == LABEL_EXPR)
3640 error ("label %s in the middle of basic block %d",
3641 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt))),
3642 bb->index);
3643 err = 1;
3646 bsi = bsi_last (bb);
3647 if (bsi_end_p (bsi))
3648 continue;
3650 stmt = bsi_stmt (bsi);
3652 err |= verify_eh_edges (stmt);
3654 if (is_ctrl_stmt (stmt))
3656 FOR_EACH_EDGE (e, ei, bb->succs)
3657 if (e->flags & EDGE_FALLTHRU)
3659 error ("fallthru edge after a control statement in bb %d",
3660 bb->index);
3661 err = 1;
3665 switch (TREE_CODE (stmt))
3667 case COND_EXPR:
3669 edge true_edge;
3670 edge false_edge;
3671 if (TREE_CODE (COND_EXPR_THEN (stmt)) != GOTO_EXPR
3672 || TREE_CODE (COND_EXPR_ELSE (stmt)) != GOTO_EXPR)
3674 error ("structured COND_EXPR at the end of bb %d", bb->index);
3675 err = 1;
3678 extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
3680 if (!true_edge || !false_edge
3681 || !(true_edge->flags & EDGE_TRUE_VALUE)
3682 || !(false_edge->flags & EDGE_FALSE_VALUE)
3683 || (true_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL))
3684 || (false_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL))
3685 || EDGE_COUNT (bb->succs) >= 3)
3687 error ("wrong outgoing edge flags at end of bb %d",
3688 bb->index);
3689 err = 1;
3692 if (!has_label_p (true_edge->dest,
3693 GOTO_DESTINATION (COND_EXPR_THEN (stmt))))
3695 error ("%<then%> label does not match edge at end of bb %d",
3696 bb->index);
3697 err = 1;
3700 if (!has_label_p (false_edge->dest,
3701 GOTO_DESTINATION (COND_EXPR_ELSE (stmt))))
3703 error ("%<else%> label does not match edge at end of bb %d",
3704 bb->index);
3705 err = 1;
3708 break;
3710 case GOTO_EXPR:
3711 if (simple_goto_p (stmt))
3713 error ("explicit goto at end of bb %d", bb->index);
3714 err = 1;
3716 else
3718 /* FIXME. We should double check that the labels in the
3719 destination blocks have their address taken. */
3720 FOR_EACH_EDGE (e, ei, bb->succs)
3721 if ((e->flags & (EDGE_FALLTHRU | EDGE_TRUE_VALUE
3722 | EDGE_FALSE_VALUE))
3723 || !(e->flags & EDGE_ABNORMAL))
3725 error ("wrong outgoing edge flags at end of bb %d",
3726 bb->index);
3727 err = 1;
3730 break;
3732 case RETURN_EXPR:
3733 if (!single_succ_p (bb)
3734 || (single_succ_edge (bb)->flags
3735 & (EDGE_FALLTHRU | EDGE_ABNORMAL
3736 | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
3738 error ("wrong outgoing edge flags at end of bb %d", bb->index);
3739 err = 1;
3741 if (single_succ (bb) != EXIT_BLOCK_PTR)
3743 error ("return edge does not point to exit in bb %d",
3744 bb->index);
3745 err = 1;
3747 break;
3749 case SWITCH_EXPR:
3751 tree prev;
3752 edge e;
3753 size_t i, n;
3754 tree vec;
3756 vec = SWITCH_LABELS (stmt);
3757 n = TREE_VEC_LENGTH (vec);
3759 /* Mark all the destination basic blocks. */
3760 for (i = 0; i < n; ++i)
3762 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
3763 basic_block label_bb = label_to_block (lab);
3765 gcc_assert (!label_bb->aux || label_bb->aux == (void *)1);
3766 label_bb->aux = (void *)1;
3769 /* Verify that the case labels are sorted. */
3770 prev = TREE_VEC_ELT (vec, 0);
3771 for (i = 1; i < n - 1; ++i)
3773 tree c = TREE_VEC_ELT (vec, i);
3774 if (! CASE_LOW (c))
3776 error ("found default case not at end of case vector");
3777 err = 1;
3778 continue;
3780 if (! tree_int_cst_lt (CASE_LOW (prev), CASE_LOW (c)))
3782 error ("case labels not sorted:");
3783 print_generic_expr (stderr, prev, 0);
3784 fprintf (stderr," is greater than ");
3785 print_generic_expr (stderr, c, 0);
3786 fprintf (stderr," but comes before it.\n");
3787 err = 1;
3789 prev = c;
3791 if (CASE_LOW (TREE_VEC_ELT (vec, n - 1)))
3793 error ("no default case found at end of case vector");
3794 err = 1;
3797 FOR_EACH_EDGE (e, ei, bb->succs)
3799 if (!e->dest->aux)
3801 error ("extra outgoing edge %d->%d",
3802 bb->index, e->dest->index);
3803 err = 1;
3805 e->dest->aux = (void *)2;
3806 if ((e->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL
3807 | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
3809 error ("wrong outgoing edge flags at end of bb %d",
3810 bb->index);
3811 err = 1;
3815 /* Check that we have all of them. */
3816 for (i = 0; i < n; ++i)
3818 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
3819 basic_block label_bb = label_to_block (lab);
3821 if (label_bb->aux != (void *)2)
3823 error ("missing edge %i->%i",
3824 bb->index, label_bb->index);
3825 err = 1;
3829 FOR_EACH_EDGE (e, ei, bb->succs)
3830 e->dest->aux = (void *)0;
3833 default: ;
3837 if (dom_computed[CDI_DOMINATORS] >= DOM_NO_FAST_QUERY)
3838 verify_dominators (CDI_DOMINATORS);
3840 return err;
3844 /* Updates phi nodes after creating a forwarder block joined
3845 by edge FALLTHRU. */
3847 static void
3848 tree_make_forwarder_block (edge fallthru)
3850 edge e;
3851 edge_iterator ei;
3852 basic_block dummy, bb;
3853 tree phi, new_phi, var;
3855 dummy = fallthru->src;
3856 bb = fallthru->dest;
3858 if (single_pred_p (bb))
3859 return;
3861 /* If we redirected a branch we must create new phi nodes at the
3862 start of BB. */
3863 for (phi = phi_nodes (dummy); phi; phi = PHI_CHAIN (phi))
3865 var = PHI_RESULT (phi);
3866 new_phi = create_phi_node (var, bb);
3867 SSA_NAME_DEF_STMT (var) = new_phi;
3868 SET_PHI_RESULT (phi, make_ssa_name (SSA_NAME_VAR (var), phi));
3869 add_phi_arg (new_phi, PHI_RESULT (phi), fallthru);
3872 /* Ensure that the PHI node chain is in the same order. */
3873 set_phi_nodes (bb, phi_reverse (phi_nodes (bb)));
3875 /* Add the arguments we have stored on edges. */
3876 FOR_EACH_EDGE (e, ei, bb->preds)
3878 if (e == fallthru)
3879 continue;
3881 flush_pending_stmts (e);
3886 /* Return a non-special label in the head of basic block BLOCK.
3887 Create one if it doesn't exist. */
3889 tree
3890 tree_block_label (basic_block bb)
3892 block_stmt_iterator i, s = bsi_start (bb);
3893 bool first = true;
3894 tree label, stmt;
3896 for (i = s; !bsi_end_p (i); first = false, bsi_next (&i))
3898 stmt = bsi_stmt (i);
3899 if (TREE_CODE (stmt) != LABEL_EXPR)
3900 break;
3901 label = LABEL_EXPR_LABEL (stmt);
3902 if (!DECL_NONLOCAL (label))
3904 if (!first)
3905 bsi_move_before (&i, &s);
3906 return label;
3910 label = create_artificial_label ();
3911 stmt = build1 (LABEL_EXPR, void_type_node, label);
3912 bsi_insert_before (&s, stmt, BSI_NEW_STMT);
3913 return label;
3917 /* Attempt to perform edge redirection by replacing a possibly complex
3918 jump instruction by a goto or by removing the jump completely.
3919 This can apply only if all edges now point to the same block. The
3920 parameters and return values are equivalent to
3921 redirect_edge_and_branch. */
3923 static edge
3924 tree_try_redirect_by_replacing_jump (edge e, basic_block target)
3926 basic_block src = e->src;
3927 block_stmt_iterator b;
3928 tree stmt;
3930 /* We can replace or remove a complex jump only when we have exactly
3931 two edges. */
3932 if (EDGE_COUNT (src->succs) != 2
3933 /* Verify that all targets will be TARGET. Specifically, the
3934 edge that is not E must also go to TARGET. */
3935 || EDGE_SUCC (src, EDGE_SUCC (src, 0) == e)->dest != target)
3936 return NULL;
3938 b = bsi_last (src);
3939 if (bsi_end_p (b))
3940 return NULL;
3941 stmt = bsi_stmt (b);
3943 if (TREE_CODE (stmt) == COND_EXPR
3944 || TREE_CODE (stmt) == SWITCH_EXPR)
3946 bsi_remove (&b);
3947 e = ssa_redirect_edge (e, target);
3948 e->flags = EDGE_FALLTHRU;
3949 return e;
3952 return NULL;
3956 /* Redirect E to DEST. Return NULL on failure. Otherwise, return the
3957 edge representing the redirected branch. */
3959 static edge
3960 tree_redirect_edge_and_branch (edge e, basic_block dest)
3962 basic_block bb = e->src;
3963 block_stmt_iterator bsi;
3964 edge ret;
3965 tree label, stmt;
3967 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
3968 return NULL;
3970 if (e->src != ENTRY_BLOCK_PTR
3971 && (ret = tree_try_redirect_by_replacing_jump (e, dest)))
3972 return ret;
3974 if (e->dest == dest)
3975 return NULL;
3977 label = tree_block_label (dest);
3979 bsi = bsi_last (bb);
3980 stmt = bsi_end_p (bsi) ? NULL : bsi_stmt (bsi);
3982 switch (stmt ? TREE_CODE (stmt) : ERROR_MARK)
3984 case COND_EXPR:
3985 stmt = (e->flags & EDGE_TRUE_VALUE
3986 ? COND_EXPR_THEN (stmt)
3987 : COND_EXPR_ELSE (stmt));
3988 GOTO_DESTINATION (stmt) = label;
3989 break;
3991 case GOTO_EXPR:
3992 /* No non-abnormal edges should lead from a non-simple goto, and
3993 simple ones should be represented implicitly. */
3994 gcc_unreachable ();
3996 case SWITCH_EXPR:
3998 tree cases = get_cases_for_edge (e, stmt);
4000 /* If we have a list of cases associated with E, then use it
4001 as it's a lot faster than walking the entire case vector. */
4002 if (cases)
4004 edge e2 = find_edge (e->src, dest);
4005 tree last, first;
4007 first = cases;
4008 while (cases)
4010 last = cases;
4011 CASE_LABEL (cases) = label;
4012 cases = TREE_CHAIN (cases);
4015 /* If there was already an edge in the CFG, then we need
4016 to move all the cases associated with E to E2. */
4017 if (e2)
4019 tree cases2 = get_cases_for_edge (e2, stmt);
4021 TREE_CHAIN (last) = TREE_CHAIN (cases2);
4022 TREE_CHAIN (cases2) = first;
4025 else
4027 tree vec = SWITCH_LABELS (stmt);
4028 size_t i, n = TREE_VEC_LENGTH (vec);
4030 for (i = 0; i < n; i++)
4032 tree elt = TREE_VEC_ELT (vec, i);
4034 if (label_to_block (CASE_LABEL (elt)) == e->dest)
4035 CASE_LABEL (elt) = label;
4039 break;
4042 case RETURN_EXPR:
4043 bsi_remove (&bsi);
4044 e->flags |= EDGE_FALLTHRU;
4045 break;
4047 default:
4048 /* Otherwise it must be a fallthru edge, and we don't need to
4049 do anything besides redirecting it. */
4050 gcc_assert (e->flags & EDGE_FALLTHRU);
4051 break;
4054 /* Update/insert PHI nodes as necessary. */
4056 /* Now update the edges in the CFG. */
4057 e = ssa_redirect_edge (e, dest);
4059 return e;
4063 /* Simple wrapper, as we can always redirect fallthru edges. */
4065 static basic_block
4066 tree_redirect_edge_and_branch_force (edge e, basic_block dest)
4068 e = tree_redirect_edge_and_branch (e, dest);
4069 gcc_assert (e);
4071 return NULL;
4075 /* Splits basic block BB after statement STMT (but at least after the
4076 labels). If STMT is NULL, BB is split just after the labels. */
4078 static basic_block
4079 tree_split_block (basic_block bb, void *stmt)
4081 block_stmt_iterator bsi, bsi_tgt;
4082 tree act;
4083 basic_block new_bb;
4084 edge e;
4085 edge_iterator ei;
4087 new_bb = create_empty_bb (bb);
4089 /* Redirect the outgoing edges. */
4090 new_bb->succs = bb->succs;
4091 bb->succs = NULL;
4092 FOR_EACH_EDGE (e, ei, new_bb->succs)
4093 e->src = new_bb;
4095 if (stmt && TREE_CODE ((tree) stmt) == LABEL_EXPR)
4096 stmt = NULL;
4098 /* Move everything from BSI to the new basic block. */
4099 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4101 act = bsi_stmt (bsi);
4102 if (TREE_CODE (act) == LABEL_EXPR)
4103 continue;
4105 if (!stmt)
4106 break;
4108 if (stmt == act)
4110 bsi_next (&bsi);
4111 break;
4115 bsi_tgt = bsi_start (new_bb);
4116 while (!bsi_end_p (bsi))
4118 act = bsi_stmt (bsi);
4119 bsi_remove (&bsi);
4120 bsi_insert_after (&bsi_tgt, act, BSI_NEW_STMT);
4123 return new_bb;
4127 /* Moves basic block BB after block AFTER. */
4129 static bool
4130 tree_move_block_after (basic_block bb, basic_block after)
4132 if (bb->prev_bb == after)
4133 return true;
4135 unlink_block (bb);
4136 link_block (bb, after);
4138 return true;
4142 /* Return true if basic_block can be duplicated. */
4144 static bool
4145 tree_can_duplicate_bb_p (basic_block bb ATTRIBUTE_UNUSED)
4147 return true;
4151 /* Create a duplicate of the basic block BB. NOTE: This does not
4152 preserve SSA form. */
4154 static basic_block
4155 tree_duplicate_bb (basic_block bb)
4157 basic_block new_bb;
4158 block_stmt_iterator bsi, bsi_tgt;
4159 tree phi;
4161 new_bb = create_empty_bb (EXIT_BLOCK_PTR->prev_bb);
4163 /* Copy the PHI nodes. We ignore PHI node arguments here because
4164 the incoming edges have not been setup yet. */
4165 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
4167 tree copy = create_phi_node (PHI_RESULT (phi), new_bb);
4168 create_new_def_for (PHI_RESULT (copy), copy, PHI_RESULT_PTR (copy));
4171 /* Keep the chain of PHI nodes in the same order so that they can be
4172 updated by ssa_redirect_edge. */
4173 set_phi_nodes (new_bb, phi_reverse (phi_nodes (new_bb)));
4175 bsi_tgt = bsi_start (new_bb);
4176 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4178 def_operand_p def_p;
4179 ssa_op_iter op_iter;
4180 tree stmt, copy;
4181 int region;
4183 stmt = bsi_stmt (bsi);
4184 if (TREE_CODE (stmt) == LABEL_EXPR)
4185 continue;
4187 /* Create a new copy of STMT and duplicate STMT's virtual
4188 operands. */
4189 copy = unshare_expr (stmt);
4190 bsi_insert_after (&bsi_tgt, copy, BSI_NEW_STMT);
4191 copy_virtual_operands (copy, stmt);
4192 region = lookup_stmt_eh_region (stmt);
4193 if (region >= 0)
4194 add_stmt_to_eh_region (copy, region);
4196 /* Create new names for all the definitions created by COPY and
4197 add replacement mappings for each new name. */
4198 FOR_EACH_SSA_DEF_OPERAND (def_p, copy, op_iter, SSA_OP_ALL_DEFS)
4199 create_new_def_for (DEF_FROM_PTR (def_p), copy, def_p);
4202 return new_bb;
4206 /* Basic block BB_COPY was created by code duplication. Add phi node
4207 arguments for edges going out of BB_COPY. The blocks that were
4208 duplicated have BB_DUPLICATED set. */
4210 void
4211 add_phi_args_after_copy_bb (basic_block bb_copy)
4213 basic_block bb, dest;
4214 edge e, e_copy;
4215 edge_iterator ei;
4216 tree phi, phi_copy, phi_next, def;
4218 bb = get_bb_original (bb_copy);
4220 FOR_EACH_EDGE (e_copy, ei, bb_copy->succs)
4222 if (!phi_nodes (e_copy->dest))
4223 continue;
4225 if (e_copy->dest->flags & BB_DUPLICATED)
4226 dest = get_bb_original (e_copy->dest);
4227 else
4228 dest = e_copy->dest;
4230 e = find_edge (bb, dest);
4231 if (!e)
4233 /* During loop unrolling the target of the latch edge is copied.
4234 In this case we are not looking for edge to dest, but to
4235 duplicated block whose original was dest. */
4236 FOR_EACH_EDGE (e, ei, bb->succs)
4237 if ((e->dest->flags & BB_DUPLICATED)
4238 && get_bb_original (e->dest) == dest)
4239 break;
4241 gcc_assert (e != NULL);
4244 for (phi = phi_nodes (e->dest), phi_copy = phi_nodes (e_copy->dest);
4245 phi;
4246 phi = phi_next, phi_copy = PHI_CHAIN (phi_copy))
4248 phi_next = PHI_CHAIN (phi);
4249 def = PHI_ARG_DEF_FROM_EDGE (phi, e);
4250 add_phi_arg (phi_copy, def, e_copy);
4255 /* Blocks in REGION_COPY array of length N_REGION were created by
4256 duplication of basic blocks. Add phi node arguments for edges
4257 going from these blocks. */
4259 void
4260 add_phi_args_after_copy (basic_block *region_copy, unsigned n_region)
4262 unsigned i;
4264 for (i = 0; i < n_region; i++)
4265 region_copy[i]->flags |= BB_DUPLICATED;
4267 for (i = 0; i < n_region; i++)
4268 add_phi_args_after_copy_bb (region_copy[i]);
4270 for (i = 0; i < n_region; i++)
4271 region_copy[i]->flags &= ~BB_DUPLICATED;
4274 /* Duplicates a REGION (set of N_REGION basic blocks) with just a single
4275 important exit edge EXIT. By important we mean that no SSA name defined
4276 inside region is live over the other exit edges of the region. All entry
4277 edges to the region must go to ENTRY->dest. The edge ENTRY is redirected
4278 to the duplicate of the region. SSA form, dominance and loop information
4279 is updated. The new basic blocks are stored to REGION_COPY in the same
4280 order as they had in REGION, provided that REGION_COPY is not NULL.
4281 The function returns false if it is unable to copy the region,
4282 true otherwise. */
4284 bool
4285 tree_duplicate_sese_region (edge entry, edge exit,
4286 basic_block *region, unsigned n_region,
4287 basic_block *region_copy)
4289 unsigned i, n_doms;
4290 bool free_region_copy = false, copying_header = false;
4291 struct loop *loop = entry->dest->loop_father;
4292 edge exit_copy;
4293 basic_block *doms;
4294 edge redirected;
4295 int total_freq = 0, entry_freq = 0;
4296 gcov_type total_count = 0, entry_count = 0;
4298 if (!can_copy_bbs_p (region, n_region))
4299 return false;
4301 /* Some sanity checking. Note that we do not check for all possible
4302 missuses of the functions. I.e. if you ask to copy something weird,
4303 it will work, but the state of structures probably will not be
4304 correct. */
4305 for (i = 0; i < n_region; i++)
4307 /* We do not handle subloops, i.e. all the blocks must belong to the
4308 same loop. */
4309 if (region[i]->loop_father != loop)
4310 return false;
4312 if (region[i] != entry->dest
4313 && region[i] == loop->header)
4314 return false;
4317 loop->copy = loop;
4319 /* In case the function is used for loop header copying (which is the primary
4320 use), ensure that EXIT and its copy will be new latch and entry edges. */
4321 if (loop->header == entry->dest)
4323 copying_header = true;
4324 loop->copy = loop->outer;
4326 if (!dominated_by_p (CDI_DOMINATORS, loop->latch, exit->src))
4327 return false;
4329 for (i = 0; i < n_region; i++)
4330 if (region[i] != exit->src
4331 && dominated_by_p (CDI_DOMINATORS, region[i], exit->src))
4332 return false;
4335 if (!region_copy)
4337 region_copy = xmalloc (sizeof (basic_block) * n_region);
4338 free_region_copy = true;
4341 gcc_assert (!need_ssa_update_p ());
4343 /* Record blocks outside the region that are dominated by something
4344 inside. */
4345 doms = xmalloc (sizeof (basic_block) * n_basic_blocks);
4346 initialize_original_copy_tables ();
4348 n_doms = get_dominated_by_region (CDI_DOMINATORS, region, n_region, doms);
4350 if (entry->dest->count)
4352 total_count = entry->dest->count;
4353 entry_count = entry->count;
4354 /* Fix up corner cases, to avoid division by zero or creation of negative
4355 frequencies. */
4356 if (entry_count > total_count)
4357 entry_count = total_count;
4359 else
4361 total_freq = entry->dest->frequency;
4362 entry_freq = EDGE_FREQUENCY (entry);
4363 /* Fix up corner cases, to avoid division by zero or creation of negative
4364 frequencies. */
4365 if (total_freq == 0)
4366 total_freq = 1;
4367 else if (entry_freq > total_freq)
4368 entry_freq = total_freq;
4371 copy_bbs (region, n_region, region_copy, &exit, 1, &exit_copy, loop,
4372 split_edge_bb_loc (entry));
4373 if (total_count)
4375 scale_bbs_frequencies_gcov_type (region, n_region,
4376 total_count - entry_count,
4377 total_count);
4378 scale_bbs_frequencies_gcov_type (region_copy, n_region, entry_count,
4379 total_count);
4381 else
4383 scale_bbs_frequencies_int (region, n_region, total_freq - entry_freq,
4384 total_freq);
4385 scale_bbs_frequencies_int (region_copy, n_region, entry_freq, total_freq);
4388 if (copying_header)
4390 loop->header = exit->dest;
4391 loop->latch = exit->src;
4394 /* Redirect the entry and add the phi node arguments. */
4395 redirected = redirect_edge_and_branch (entry, get_bb_copy (entry->dest));
4396 gcc_assert (redirected != NULL);
4397 flush_pending_stmts (entry);
4399 /* Concerning updating of dominators: We must recount dominators
4400 for entry block and its copy. Anything that is outside of the
4401 region, but was dominated by something inside needs recounting as
4402 well. */
4403 set_immediate_dominator (CDI_DOMINATORS, entry->dest, entry->src);
4404 doms[n_doms++] = get_bb_original (entry->dest);
4405 iterate_fix_dominators (CDI_DOMINATORS, doms, n_doms);
4406 free (doms);
4408 /* Add the other PHI node arguments. */
4409 add_phi_args_after_copy (region_copy, n_region);
4411 /* Update the SSA web. */
4412 update_ssa (TODO_update_ssa);
4414 if (free_region_copy)
4415 free (region_copy);
4417 free_original_copy_tables ();
4418 return true;
4422 /* Dump FUNCTION_DECL FN to file FILE using FLAGS (see TDF_* in tree.h) */
4424 void
4425 dump_function_to_file (tree fn, FILE *file, int flags)
4427 tree arg, vars, var;
4428 bool ignore_topmost_bind = false, any_var = false;
4429 basic_block bb;
4430 tree chain;
4432 fprintf (file, "%s (", lang_hooks.decl_printable_name (fn, 2));
4434 arg = DECL_ARGUMENTS (fn);
4435 while (arg)
4437 print_generic_expr (file, arg, dump_flags);
4438 if (TREE_CHAIN (arg))
4439 fprintf (file, ", ");
4440 arg = TREE_CHAIN (arg);
4442 fprintf (file, ")\n");
4444 if (flags & TDF_DETAILS)
4445 dump_eh_tree (file, DECL_STRUCT_FUNCTION (fn));
4446 if (flags & TDF_RAW)
4448 dump_node (fn, TDF_SLIM | flags, file);
4449 return;
4452 /* When GIMPLE is lowered, the variables are no longer available in
4453 BIND_EXPRs, so display them separately. */
4454 if (cfun && cfun->decl == fn && cfun->unexpanded_var_list)
4456 ignore_topmost_bind = true;
4458 fprintf (file, "{\n");
4459 for (vars = cfun->unexpanded_var_list; vars; vars = TREE_CHAIN (vars))
4461 var = TREE_VALUE (vars);
4463 print_generic_decl (file, var, flags);
4464 fprintf (file, "\n");
4466 any_var = true;
4470 if (cfun && cfun->decl == fn && cfun->cfg && basic_block_info)
4472 /* Make a CFG based dump. */
4473 check_bb_profile (ENTRY_BLOCK_PTR, file);
4474 if (!ignore_topmost_bind)
4475 fprintf (file, "{\n");
4477 if (any_var && n_basic_blocks)
4478 fprintf (file, "\n");
4480 FOR_EACH_BB (bb)
4481 dump_generic_bb (file, bb, 2, flags);
4483 fprintf (file, "}\n");
4484 check_bb_profile (EXIT_BLOCK_PTR, file);
4486 else
4488 int indent;
4490 /* Make a tree based dump. */
4491 chain = DECL_SAVED_TREE (fn);
4493 if (TREE_CODE (chain) == BIND_EXPR)
4495 if (ignore_topmost_bind)
4497 chain = BIND_EXPR_BODY (chain);
4498 indent = 2;
4500 else
4501 indent = 0;
4503 else
4505 if (!ignore_topmost_bind)
4506 fprintf (file, "{\n");
4507 indent = 2;
4510 if (any_var)
4511 fprintf (file, "\n");
4513 print_generic_stmt_indented (file, chain, flags, indent);
4514 if (ignore_topmost_bind)
4515 fprintf (file, "}\n");
4518 fprintf (file, "\n\n");
4522 /* Pretty print of the loops intermediate representation. */
4523 static void print_loop (FILE *, struct loop *, int);
4524 static void print_pred_bbs (FILE *, basic_block bb);
4525 static void print_succ_bbs (FILE *, basic_block bb);
4528 /* Print on FILE the indexes for the predecessors of basic_block BB. */
4530 static void
4531 print_pred_bbs (FILE *file, basic_block bb)
4533 edge e;
4534 edge_iterator ei;
4536 FOR_EACH_EDGE (e, ei, bb->preds)
4537 fprintf (file, "bb_%d ", e->src->index);
4541 /* Print on FILE the indexes for the successors of basic_block BB. */
4543 static void
4544 print_succ_bbs (FILE *file, basic_block bb)
4546 edge e;
4547 edge_iterator ei;
4549 FOR_EACH_EDGE (e, ei, bb->succs)
4550 fprintf (file, "bb_%d ", e->dest->index);
4554 /* Pretty print LOOP on FILE, indented INDENT spaces. */
4556 static void
4557 print_loop (FILE *file, struct loop *loop, int indent)
4559 char *s_indent;
4560 basic_block bb;
4562 if (loop == NULL)
4563 return;
4565 s_indent = (char *) alloca ((size_t) indent + 1);
4566 memset ((void *) s_indent, ' ', (size_t) indent);
4567 s_indent[indent] = '\0';
4569 /* Print the loop's header. */
4570 fprintf (file, "%sloop_%d\n", s_indent, loop->num);
4572 /* Print the loop's body. */
4573 fprintf (file, "%s{\n", s_indent);
4574 FOR_EACH_BB (bb)
4575 if (bb->loop_father == loop)
4577 /* Print the basic_block's header. */
4578 fprintf (file, "%s bb_%d (preds = {", s_indent, bb->index);
4579 print_pred_bbs (file, bb);
4580 fprintf (file, "}, succs = {");
4581 print_succ_bbs (file, bb);
4582 fprintf (file, "})\n");
4584 /* Print the basic_block's body. */
4585 fprintf (file, "%s {\n", s_indent);
4586 tree_dump_bb (bb, file, indent + 4);
4587 fprintf (file, "%s }\n", s_indent);
4590 print_loop (file, loop->inner, indent + 2);
4591 fprintf (file, "%s}\n", s_indent);
4592 print_loop (file, loop->next, indent);
4596 /* Follow a CFG edge from the entry point of the program, and on entry
4597 of a loop, pretty print the loop structure on FILE. */
4599 void
4600 print_loop_ir (FILE *file)
4602 basic_block bb;
4604 bb = BASIC_BLOCK (0);
4605 if (bb && bb->loop_father)
4606 print_loop (file, bb->loop_father, 0);
4610 /* Debugging loops structure at tree level. */
4612 void
4613 debug_loop_ir (void)
4615 print_loop_ir (stderr);
4619 /* Return true if BB ends with a call, possibly followed by some
4620 instructions that must stay with the call. Return false,
4621 otherwise. */
4623 static bool
4624 tree_block_ends_with_call_p (basic_block bb)
4626 block_stmt_iterator bsi = bsi_last (bb);
4627 return get_call_expr_in (bsi_stmt (bsi)) != NULL;
4631 /* Return true if BB ends with a conditional branch. Return false,
4632 otherwise. */
4634 static bool
4635 tree_block_ends_with_condjump_p (basic_block bb)
4637 tree stmt = last_stmt (bb);
4638 return (stmt && TREE_CODE (stmt) == COND_EXPR);
4642 /* Return true if we need to add fake edge to exit at statement T.
4643 Helper function for tree_flow_call_edges_add. */
4645 static bool
4646 need_fake_edge_p (tree t)
4648 tree call;
4650 /* NORETURN and LONGJMP calls already have an edge to exit.
4651 CONST and PURE calls do not need one.
4652 We don't currently check for CONST and PURE here, although
4653 it would be a good idea, because those attributes are
4654 figured out from the RTL in mark_constant_function, and
4655 the counter incrementation code from -fprofile-arcs
4656 leads to different results from -fbranch-probabilities. */
4657 call = get_call_expr_in (t);
4658 if (call
4659 && !(call_expr_flags (call) & ECF_NORETURN))
4660 return true;
4662 if (TREE_CODE (t) == ASM_EXPR
4663 && (ASM_VOLATILE_P (t) || ASM_INPUT_P (t)))
4664 return true;
4666 return false;
4670 /* Add fake edges to the function exit for any non constant and non
4671 noreturn calls, volatile inline assembly in the bitmap of blocks
4672 specified by BLOCKS or to the whole CFG if BLOCKS is zero. Return
4673 the number of blocks that were split.
4675 The goal is to expose cases in which entering a basic block does
4676 not imply that all subsequent instructions must be executed. */
4678 static int
4679 tree_flow_call_edges_add (sbitmap blocks)
4681 int i;
4682 int blocks_split = 0;
4683 int last_bb = last_basic_block;
4684 bool check_last_block = false;
4686 if (n_basic_blocks == 0)
4687 return 0;
4689 if (! blocks)
4690 check_last_block = true;
4691 else
4692 check_last_block = TEST_BIT (blocks, EXIT_BLOCK_PTR->prev_bb->index);
4694 /* In the last basic block, before epilogue generation, there will be
4695 a fallthru edge to EXIT. Special care is required if the last insn
4696 of the last basic block is a call because make_edge folds duplicate
4697 edges, which would result in the fallthru edge also being marked
4698 fake, which would result in the fallthru edge being removed by
4699 remove_fake_edges, which would result in an invalid CFG.
4701 Moreover, we can't elide the outgoing fake edge, since the block
4702 profiler needs to take this into account in order to solve the minimal
4703 spanning tree in the case that the call doesn't return.
4705 Handle this by adding a dummy instruction in a new last basic block. */
4706 if (check_last_block)
4708 basic_block bb = EXIT_BLOCK_PTR->prev_bb;
4709 block_stmt_iterator bsi = bsi_last (bb);
4710 tree t = NULL_TREE;
4711 if (!bsi_end_p (bsi))
4712 t = bsi_stmt (bsi);
4714 if (need_fake_edge_p (t))
4716 edge e;
4718 e = find_edge (bb, EXIT_BLOCK_PTR);
4719 if (e)
4721 bsi_insert_on_edge (e, build_empty_stmt ());
4722 bsi_commit_edge_inserts ();
4727 /* Now add fake edges to the function exit for any non constant
4728 calls since there is no way that we can determine if they will
4729 return or not... */
4730 for (i = 0; i < last_bb; i++)
4732 basic_block bb = BASIC_BLOCK (i);
4733 block_stmt_iterator bsi;
4734 tree stmt, last_stmt;
4736 if (!bb)
4737 continue;
4739 if (blocks && !TEST_BIT (blocks, i))
4740 continue;
4742 bsi = bsi_last (bb);
4743 if (!bsi_end_p (bsi))
4745 last_stmt = bsi_stmt (bsi);
4748 stmt = bsi_stmt (bsi);
4749 if (need_fake_edge_p (stmt))
4751 edge e;
4752 /* The handling above of the final block before the
4753 epilogue should be enough to verify that there is
4754 no edge to the exit block in CFG already.
4755 Calling make_edge in such case would cause us to
4756 mark that edge as fake and remove it later. */
4757 #ifdef ENABLE_CHECKING
4758 if (stmt == last_stmt)
4760 e = find_edge (bb, EXIT_BLOCK_PTR);
4761 gcc_assert (e == NULL);
4763 #endif
4765 /* Note that the following may create a new basic block
4766 and renumber the existing basic blocks. */
4767 if (stmt != last_stmt)
4769 e = split_block (bb, stmt);
4770 if (e)
4771 blocks_split++;
4773 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
4775 bsi_prev (&bsi);
4777 while (!bsi_end_p (bsi));
4781 if (blocks_split)
4782 verify_flow_info ();
4784 return blocks_split;
4787 bool
4788 tree_purge_dead_eh_edges (basic_block bb)
4790 bool changed = false;
4791 edge e;
4792 edge_iterator ei;
4793 tree stmt = last_stmt (bb);
4795 if (stmt && tree_can_throw_internal (stmt))
4796 return false;
4798 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
4800 if (e->flags & EDGE_EH)
4802 remove_edge (e);
4803 changed = true;
4805 else
4806 ei_next (&ei);
4809 /* Removal of dead EH edges might change dominators of not
4810 just immediate successors. E.g. when bb1 is changed so that
4811 it no longer can throw and bb1->bb3 and bb1->bb4 are dead
4812 eh edges purged by this function in:
4816 1-->2
4817 / \ |
4818 v v |
4819 3-->4 |
4821 --->5
4824 idom(bb5) must be recomputed. For now just free the dominance
4825 info. */
4826 if (changed)
4827 free_dominance_info (CDI_DOMINATORS);
4829 return changed;
4832 bool
4833 tree_purge_all_dead_eh_edges (bitmap blocks)
4835 bool changed = false;
4836 unsigned i;
4837 bitmap_iterator bi;
4839 EXECUTE_IF_SET_IN_BITMAP (blocks, 0, i, bi)
4841 changed |= tree_purge_dead_eh_edges (BASIC_BLOCK (i));
4844 return changed;
4847 /* This function is called whenever a new edge is created or
4848 redirected. */
4850 static void
4851 tree_execute_on_growing_pred (edge e)
4853 basic_block bb = e->dest;
4855 if (phi_nodes (bb))
4856 reserve_phi_args_for_new_edge (bb);
4859 /* This function is called immediately before edge E is removed from
4860 the edge vector E->dest->preds. */
4862 static void
4863 tree_execute_on_shrinking_pred (edge e)
4865 if (phi_nodes (e->dest))
4866 remove_phi_args (e);
4869 /*---------------------------------------------------------------------------
4870 Helper functions for Loop versioning
4871 ---------------------------------------------------------------------------*/
4873 /* Adjust phi nodes for 'first' basic block. 'second' basic block is a copy
4874 of 'first'. Both of them are dominated by 'new_head' basic block. When
4875 'new_head' was created by 'second's incoming edge it received phi arguments
4876 on the edge by split_edge(). Later, additional edge 'e' was created to
4877 connect 'new_head' and 'first'. Now this routine adds phi args on this
4878 additional edge 'e' that new_head to second edge received as part of edge
4879 splitting.
4882 static void
4883 tree_lv_adjust_loop_header_phi (basic_block first, basic_block second,
4884 basic_block new_head, edge e)
4886 tree phi1, phi2;
4887 edge e2 = find_edge (new_head, second);
4889 /* Because NEW_HEAD has been created by splitting SECOND's incoming
4890 edge, we should always have an edge from NEW_HEAD to SECOND. */
4891 gcc_assert (e2 != NULL);
4893 /* Browse all 'second' basic block phi nodes and add phi args to
4894 edge 'e' for 'first' head. PHI args are always in correct order. */
4896 for (phi2 = phi_nodes (second), phi1 = phi_nodes (first);
4897 phi2 && phi1;
4898 phi2 = PHI_CHAIN (phi2), phi1 = PHI_CHAIN (phi1))
4900 tree def = PHI_ARG_DEF (phi2, e2->dest_idx);
4901 add_phi_arg (phi1, def, e);
4905 /* Adds a if else statement to COND_BB with condition COND_EXPR.
4906 SECOND_HEAD is the destination of the THEN and FIRST_HEAD is
4907 the destination of the ELSE part. */
4908 static void
4909 tree_lv_add_condition_to_bb (basic_block first_head, basic_block second_head,
4910 basic_block cond_bb, void *cond_e)
4912 block_stmt_iterator bsi;
4913 tree goto1 = NULL_TREE;
4914 tree goto2 = NULL_TREE;
4915 tree new_cond_expr = NULL_TREE;
4916 tree cond_expr = (tree) cond_e;
4917 edge e0;
4919 /* Build new conditional expr */
4920 goto1 = build1 (GOTO_EXPR, void_type_node, tree_block_label (first_head));
4921 goto2 = build1 (GOTO_EXPR, void_type_node, tree_block_label (second_head));
4922 new_cond_expr = build3 (COND_EXPR, void_type_node, cond_expr, goto1, goto2);
4924 /* Add new cond in cond_bb. */
4925 bsi = bsi_start (cond_bb);
4926 bsi_insert_after (&bsi, new_cond_expr, BSI_NEW_STMT);
4927 /* Adjust edges appropriately to connect new head with first head
4928 as well as second head. */
4929 e0 = single_succ_edge (cond_bb);
4930 e0->flags &= ~EDGE_FALLTHRU;
4931 e0->flags |= EDGE_FALSE_VALUE;
4934 struct cfg_hooks tree_cfg_hooks = {
4935 "tree",
4936 tree_verify_flow_info,
4937 tree_dump_bb, /* dump_bb */
4938 create_bb, /* create_basic_block */
4939 tree_redirect_edge_and_branch,/* redirect_edge_and_branch */
4940 tree_redirect_edge_and_branch_force,/* redirect_edge_and_branch_force */
4941 remove_bb, /* delete_basic_block */
4942 tree_split_block, /* split_block */
4943 tree_move_block_after, /* move_block_after */
4944 tree_can_merge_blocks_p, /* can_merge_blocks_p */
4945 tree_merge_blocks, /* merge_blocks */
4946 tree_predict_edge, /* predict_edge */
4947 tree_predicted_by_p, /* predicted_by_p */
4948 tree_can_duplicate_bb_p, /* can_duplicate_block_p */
4949 tree_duplicate_bb, /* duplicate_block */
4950 tree_split_edge, /* split_edge */
4951 tree_make_forwarder_block, /* make_forward_block */
4952 NULL, /* tidy_fallthru_edge */
4953 tree_block_ends_with_call_p, /* block_ends_with_call_p */
4954 tree_block_ends_with_condjump_p, /* block_ends_with_condjump_p */
4955 tree_flow_call_edges_add, /* flow_call_edges_add */
4956 tree_execute_on_growing_pred, /* execute_on_growing_pred */
4957 tree_execute_on_shrinking_pred, /* execute_on_shrinking_pred */
4958 tree_duplicate_loop_to_header_edge, /* duplicate loop for trees */
4959 tree_lv_add_condition_to_bb, /* lv_add_condition_to_bb */
4960 tree_lv_adjust_loop_header_phi, /* lv_adjust_loop_header_phi*/
4961 extract_true_false_edges_from_block, /* extract_cond_bb_edges */
4962 flush_pending_stmts /* flush_pending_stmts */
4966 /* Split all critical edges. */
4968 static void
4969 split_critical_edges (void)
4971 basic_block bb;
4972 edge e;
4973 edge_iterator ei;
4975 /* split_edge can redirect edges out of SWITCH_EXPRs, which can get
4976 expensive. So we want to enable recording of edge to CASE_LABEL_EXPR
4977 mappings around the calls to split_edge. */
4978 start_recording_case_labels ();
4979 FOR_ALL_BB (bb)
4981 FOR_EACH_EDGE (e, ei, bb->succs)
4982 if (EDGE_CRITICAL_P (e) && !(e->flags & EDGE_ABNORMAL))
4984 split_edge (e);
4987 end_recording_case_labels ();
4990 struct tree_opt_pass pass_split_crit_edges =
4992 "crited", /* name */
4993 NULL, /* gate */
4994 split_critical_edges, /* execute */
4995 NULL, /* sub */
4996 NULL, /* next */
4997 0, /* static_pass_number */
4998 TV_TREE_SPLIT_EDGES, /* tv_id */
4999 PROP_cfg, /* properties required */
5000 PROP_no_crit_edges, /* properties_provided */
5001 0, /* properties_destroyed */
5002 0, /* todo_flags_start */
5003 TODO_dump_func, /* todo_flags_finish */
5004 0 /* letter */
5008 /* Return EXP if it is a valid GIMPLE rvalue, else gimplify it into
5009 a temporary, make sure and register it to be renamed if necessary,
5010 and finally return the temporary. Put the statements to compute
5011 EXP before the current statement in BSI. */
5013 tree
5014 gimplify_val (block_stmt_iterator *bsi, tree type, tree exp)
5016 tree t, new_stmt, orig_stmt;
5018 if (is_gimple_val (exp))
5019 return exp;
5021 t = make_rename_temp (type, NULL);
5022 new_stmt = build (MODIFY_EXPR, type, t, exp);
5024 orig_stmt = bsi_stmt (*bsi);
5025 SET_EXPR_LOCUS (new_stmt, EXPR_LOCUS (orig_stmt));
5026 TREE_BLOCK (new_stmt) = TREE_BLOCK (orig_stmt);
5028 bsi_insert_before (bsi, new_stmt, BSI_SAME_STMT);
5030 return t;
5033 /* Build a ternary operation and gimplify it. Emit code before BSI.
5034 Return the gimple_val holding the result. */
5036 tree
5037 gimplify_build3 (block_stmt_iterator *bsi, enum tree_code code,
5038 tree type, tree a, tree b, tree c)
5040 tree ret;
5042 ret = fold_build3 (code, type, a, b, c);
5043 STRIP_NOPS (ret);
5045 return gimplify_val (bsi, type, ret);
5048 /* Build a binary operation and gimplify it. Emit code before BSI.
5049 Return the gimple_val holding the result. */
5051 tree
5052 gimplify_build2 (block_stmt_iterator *bsi, enum tree_code code,
5053 tree type, tree a, tree b)
5055 tree ret;
5057 ret = fold_build2 (code, type, a, b);
5058 STRIP_NOPS (ret);
5060 return gimplify_val (bsi, type, ret);
5063 /* Build a unary operation and gimplify it. Emit code before BSI.
5064 Return the gimple_val holding the result. */
5066 tree
5067 gimplify_build1 (block_stmt_iterator *bsi, enum tree_code code, tree type,
5068 tree a)
5070 tree ret;
5072 ret = fold_build1 (code, type, a);
5073 STRIP_NOPS (ret);
5075 return gimplify_val (bsi, type, ret);
5080 /* Emit return warnings. */
5082 static void
5083 execute_warn_function_return (void)
5085 #ifdef USE_MAPPED_LOCATION
5086 source_location location;
5087 #else
5088 location_t *locus;
5089 #endif
5090 tree last;
5091 edge e;
5092 edge_iterator ei;
5094 /* If we have a path to EXIT, then we do return. */
5095 if (TREE_THIS_VOLATILE (cfun->decl)
5096 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) > 0)
5098 #ifdef USE_MAPPED_LOCATION
5099 location = UNKNOWN_LOCATION;
5100 #else
5101 locus = NULL;
5102 #endif
5103 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
5105 last = last_stmt (e->src);
5106 if (TREE_CODE (last) == RETURN_EXPR
5107 #ifdef USE_MAPPED_LOCATION
5108 && (location = EXPR_LOCATION (last)) != UNKNOWN_LOCATION)
5109 #else
5110 && (locus = EXPR_LOCUS (last)) != NULL)
5111 #endif
5112 break;
5114 #ifdef USE_MAPPED_LOCATION
5115 if (location == UNKNOWN_LOCATION)
5116 location = cfun->function_end_locus;
5117 warning (0, "%H%<noreturn%> function does return", &location);
5118 #else
5119 if (!locus)
5120 locus = &cfun->function_end_locus;
5121 warning (0, "%H%<noreturn%> function does return", locus);
5122 #endif
5125 /* If we see "return;" in some basic block, then we do reach the end
5126 without returning a value. */
5127 else if (warn_return_type
5128 && !TREE_NO_WARNING (cfun->decl)
5129 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) > 0
5130 && !VOID_TYPE_P (TREE_TYPE (TREE_TYPE (cfun->decl))))
5132 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
5134 tree last = last_stmt (e->src);
5135 if (TREE_CODE (last) == RETURN_EXPR
5136 && TREE_OPERAND (last, 0) == NULL
5137 && !TREE_NO_WARNING (last))
5139 #ifdef USE_MAPPED_LOCATION
5140 location = EXPR_LOCATION (last);
5141 if (location == UNKNOWN_LOCATION)
5142 location = cfun->function_end_locus;
5143 warning (0, "%Hcontrol reaches end of non-void function", &location);
5144 #else
5145 locus = EXPR_LOCUS (last);
5146 if (!locus)
5147 locus = &cfun->function_end_locus;
5148 warning (0, "%Hcontrol reaches end of non-void function", locus);
5149 #endif
5150 TREE_NO_WARNING (cfun->decl) = 1;
5151 break;
5158 /* Given a basic block B which ends with a conditional and has
5159 precisely two successors, determine which of the edges is taken if
5160 the conditional is true and which is taken if the conditional is
5161 false. Set TRUE_EDGE and FALSE_EDGE appropriately. */
5163 void
5164 extract_true_false_edges_from_block (basic_block b,
5165 edge *true_edge,
5166 edge *false_edge)
5168 edge e = EDGE_SUCC (b, 0);
5170 if (e->flags & EDGE_TRUE_VALUE)
5172 *true_edge = e;
5173 *false_edge = EDGE_SUCC (b, 1);
5175 else
5177 *false_edge = e;
5178 *true_edge = EDGE_SUCC (b, 1);
5182 struct tree_opt_pass pass_warn_function_return =
5184 NULL, /* name */
5185 NULL, /* gate */
5186 execute_warn_function_return, /* execute */
5187 NULL, /* sub */
5188 NULL, /* next */
5189 0, /* static_pass_number */
5190 0, /* tv_id */
5191 PROP_cfg, /* properties_required */
5192 0, /* properties_provided */
5193 0, /* properties_destroyed */
5194 0, /* todo_flags_start */
5195 0, /* todo_flags_finish */
5196 0 /* letter */
5199 /* Emit noreturn warnings. */
5201 static void
5202 execute_warn_function_noreturn (void)
5204 if (warn_missing_noreturn
5205 && !TREE_THIS_VOLATILE (cfun->decl)
5206 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) == 0
5207 && !lang_hooks.function.missing_noreturn_ok_p (cfun->decl))
5208 warning (OPT_Wmissing_noreturn, "%Jfunction might be possible candidate "
5209 "for attribute %<noreturn%>",
5210 cfun->decl);
5213 struct tree_opt_pass pass_warn_function_noreturn =
5215 NULL, /* name */
5216 NULL, /* gate */
5217 execute_warn_function_noreturn, /* execute */
5218 NULL, /* sub */
5219 NULL, /* next */
5220 0, /* static_pass_number */
5221 0, /* tv_id */
5222 PROP_cfg, /* properties_required */
5223 0, /* properties_provided */
5224 0, /* properties_destroyed */
5225 0, /* todo_flags_start */
5226 0, /* todo_flags_finish */
5227 0 /* letter */