1 /* Control flow functions for trees.
2 Copyright (C) 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
3 Contributed by Diego Novillo <dnovillo@redhat.com>
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 GCC is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to
19 the Free Software Foundation, 51 Franklin Street, Fifth Floor,
20 Boston, MA 02110-1301, USA. */
24 #include "coretypes.h"
29 #include "hard-reg-set.h"
30 #include "basic-block.h"
36 #include "langhooks.h"
37 #include "diagnostic.h"
38 #include "tree-flow.h"
40 #include "tree-dump.h"
41 #include "tree-pass.h"
45 #include "cfglayout.h"
47 #include "tree-ssa-propagate.h"
49 /* This file contains functions for building the Control Flow Graph (CFG)
50 for a function tree. */
52 /* Local declarations. */
54 /* Initial capacity for the basic block array. */
55 static const int initial_cfg_capacity = 20;
57 /* This hash table allows us to efficiently lookup all CASE_LABEL_EXPRs
58 which use a particular edge. The CASE_LABEL_EXPRs are chained together
59 via their TREE_CHAIN field, which we clear after we're done with the
60 hash table to prevent problems with duplication of SWITCH_EXPRs.
62 Access to this list of CASE_LABEL_EXPRs allows us to efficiently
63 update the case vector in response to edge redirections.
65 Right now this table is set up and torn down at key points in the
66 compilation process. It would be nice if we could make the table
67 more persistent. The key is getting notification of changes to
68 the CFG (particularly edge removal, creation and redirection). */
70 struct edge_to_cases_elt
72 /* The edge itself. Necessary for hashing and equality tests. */
75 /* The case labels associated with this edge. We link these up via
76 their TREE_CHAIN field, then we wipe out the TREE_CHAIN fields
77 when we destroy the hash table. This prevents problems when copying
82 static htab_t edge_to_cases;
87 long num_merged_labels;
90 static struct cfg_stats_d cfg_stats;
92 /* Nonzero if we found a computed goto while building basic blocks. */
93 static bool found_computed_goto;
95 /* Basic blocks and flowgraphs. */
96 static basic_block create_bb (void *, void *, basic_block);
97 static void make_blocks (tree);
98 static void factor_computed_gotos (void);
101 static void make_edges (void);
102 static void make_ctrl_stmt_edges (basic_block);
103 static void make_exit_edges (basic_block);
104 static void make_cond_expr_edges (basic_block);
105 static void make_switch_expr_edges (basic_block);
106 static void make_goto_expr_edges (basic_block);
107 static edge tree_redirect_edge_and_branch (edge, basic_block);
108 static edge tree_try_redirect_by_replacing_jump (edge, basic_block);
109 static void split_critical_edges (void);
111 /* Various helpers. */
112 static inline bool stmt_starts_bb_p (tree, tree);
113 static int tree_verify_flow_info (void);
114 static void tree_make_forwarder_block (edge);
115 static void tree_cfg2vcg (FILE *);
117 /* Flowgraph optimization and cleanup. */
118 static void tree_merge_blocks (basic_block, basic_block);
119 static bool tree_can_merge_blocks_p (basic_block, basic_block);
120 static void remove_bb (basic_block);
121 static edge find_taken_edge_computed_goto (basic_block, tree);
122 static edge find_taken_edge_cond_expr (basic_block, tree);
123 static edge find_taken_edge_switch_expr (basic_block, tree);
124 static tree find_case_label_for_value (tree, tree);
127 init_empty_tree_cfg (void)
129 /* Initialize the basic block array. */
131 profile_status = PROFILE_ABSENT;
133 last_basic_block = 0;
134 VARRAY_BB_INIT (basic_block_info, initial_cfg_capacity, "basic_block_info");
136 /* Build a mapping of labels to their associated blocks. */
137 VARRAY_BB_INIT (label_to_block_map, initial_cfg_capacity,
138 "label to block map");
140 ENTRY_BLOCK_PTR->next_bb = EXIT_BLOCK_PTR;
141 EXIT_BLOCK_PTR->prev_bb = ENTRY_BLOCK_PTR;
144 /*---------------------------------------------------------------------------
146 ---------------------------------------------------------------------------*/
148 /* Entry point to the CFG builder for trees. TP points to the list of
149 statements to be added to the flowgraph. */
152 build_tree_cfg (tree *tp)
154 /* Register specific tree functions. */
155 tree_register_cfg_hooks ();
157 memset ((void *) &cfg_stats, 0, sizeof (cfg_stats));
159 init_empty_tree_cfg ();
161 found_computed_goto = 0;
164 /* Computed gotos are hell to deal with, especially if there are
165 lots of them with a large number of destinations. So we factor
166 them to a common computed goto location before we build the
167 edge list. After we convert back to normal form, we will un-factor
168 the computed gotos since factoring introduces an unwanted jump. */
169 if (found_computed_goto)
170 factor_computed_gotos ();
172 /* Make sure there is always at least one block, even if it's empty. */
173 if (n_basic_blocks == 0)
174 create_empty_bb (ENTRY_BLOCK_PTR);
176 /* Adjust the size of the array. */
177 VARRAY_GROW (basic_block_info, n_basic_blocks);
179 /* To speed up statement iterator walks, we first purge dead labels. */
180 cleanup_dead_labels ();
182 /* Group case nodes to reduce the number of edges.
183 We do this after cleaning up dead labels because otherwise we miss
184 a lot of obvious case merging opportunities. */
185 group_case_labels ();
187 /* Create the edges of the flowgraph. */
190 /* Debugging dumps. */
192 /* Write the flowgraph to a VCG file. */
194 int local_dump_flags;
195 FILE *dump_file = dump_begin (TDI_vcg, &local_dump_flags);
198 tree_cfg2vcg (dump_file);
199 dump_end (TDI_vcg, dump_file);
203 #ifdef ENABLE_CHECKING
207 /* Dump a textual representation of the flowgraph. */
209 dump_tree_cfg (dump_file, dump_flags);
213 execute_build_cfg (void)
215 build_tree_cfg (&DECL_SAVED_TREE (current_function_decl));
218 struct tree_opt_pass pass_build_cfg =
222 execute_build_cfg, /* execute */
225 0, /* static_pass_number */
226 TV_TREE_CFG, /* tv_id */
227 PROP_gimple_leh, /* properties_required */
228 PROP_cfg, /* properties_provided */
229 0, /* properties_destroyed */
230 0, /* todo_flags_start */
231 TODO_verify_stmts, /* todo_flags_finish */
235 /* Search the CFG for any computed gotos. If found, factor them to a
236 common computed goto site. Also record the location of that site so
237 that we can un-factor the gotos after we have converted back to
241 factor_computed_gotos (void)
244 tree factored_label_decl = NULL;
246 tree factored_computed_goto_label = NULL;
247 tree factored_computed_goto = NULL;
249 /* We know there are one or more computed gotos in this function.
250 Examine the last statement in each basic block to see if the block
251 ends with a computed goto. */
255 block_stmt_iterator bsi = bsi_last (bb);
260 last = bsi_stmt (bsi);
262 /* Ignore the computed goto we create when we factor the original
264 if (last == factored_computed_goto)
267 /* If the last statement is a computed goto, factor it. */
268 if (computed_goto_p (last))
272 /* The first time we find a computed goto we need to create
273 the factored goto block and the variable each original
274 computed goto will use for their goto destination. */
275 if (! factored_computed_goto)
277 basic_block new_bb = create_empty_bb (bb);
278 block_stmt_iterator new_bsi = bsi_start (new_bb);
280 /* Create the destination of the factored goto. Each original
281 computed goto will put its desired destination into this
282 variable and jump to the label we create immediately
284 var = create_tmp_var (ptr_type_node, "gotovar");
286 /* Build a label for the new block which will contain the
287 factored computed goto. */
288 factored_label_decl = create_artificial_label ();
289 factored_computed_goto_label
290 = build1 (LABEL_EXPR, void_type_node, factored_label_decl);
291 bsi_insert_after (&new_bsi, factored_computed_goto_label,
294 /* Build our new computed goto. */
295 factored_computed_goto = build1 (GOTO_EXPR, void_type_node, var);
296 bsi_insert_after (&new_bsi, factored_computed_goto,
300 /* Copy the original computed goto's destination into VAR. */
301 assignment = build (MODIFY_EXPR, ptr_type_node,
302 var, GOTO_DESTINATION (last));
303 bsi_insert_before (&bsi, assignment, BSI_SAME_STMT);
305 /* And re-vector the computed goto to the new destination. */
306 GOTO_DESTINATION (last) = factored_label_decl;
312 /* Build a flowgraph for the statement_list STMT_LIST. */
315 make_blocks (tree stmt_list)
317 tree_stmt_iterator i = tsi_start (stmt_list);
319 bool start_new_block = true;
320 bool first_stmt_of_list = true;
321 basic_block bb = ENTRY_BLOCK_PTR;
323 while (!tsi_end_p (i))
330 /* If the statement starts a new basic block or if we have determined
331 in a previous pass that we need to create a new block for STMT, do
333 if (start_new_block || stmt_starts_bb_p (stmt, prev_stmt))
335 if (!first_stmt_of_list)
336 stmt_list = tsi_split_statement_list_before (&i);
337 bb = create_basic_block (stmt_list, NULL, bb);
338 start_new_block = false;
341 /* Now add STMT to BB and create the subgraphs for special statement
343 set_bb_for_stmt (stmt, bb);
345 if (computed_goto_p (stmt))
346 found_computed_goto = true;
348 /* If STMT is a basic block terminator, set START_NEW_BLOCK for the
350 if (stmt_ends_bb_p (stmt))
351 start_new_block = true;
354 first_stmt_of_list = false;
359 /* Create and return a new empty basic block after bb AFTER. */
362 create_bb (void *h, void *e, basic_block after)
368 /* Create and initialize a new basic block. Since alloc_block uses
369 ggc_alloc_cleared to allocate a basic block, we do not have to
370 clear the newly allocated basic block here. */
373 bb->index = last_basic_block;
375 bb->stmt_list = h ? h : alloc_stmt_list ();
377 /* Add the new block to the linked list of blocks. */
378 link_block (bb, after);
380 /* Grow the basic block array if needed. */
381 if ((size_t) last_basic_block == VARRAY_SIZE (basic_block_info))
383 size_t new_size = last_basic_block + (last_basic_block + 3) / 4;
384 VARRAY_GROW (basic_block_info, new_size);
387 /* Add the newly created block to the array. */
388 BASIC_BLOCK (last_basic_block) = bb;
397 /*---------------------------------------------------------------------------
399 ---------------------------------------------------------------------------*/
401 /* Fold COND_EXPR_COND of each COND_EXPR. */
404 fold_cond_expr_cond (void)
410 tree stmt = last_stmt (bb);
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. */
431 /* Create an edge from entry to the first block with executable
433 make_edge (ENTRY_BLOCK_PTR, BASIC_BLOCK (0), EDGE_FALLTHRU);
435 /* Traverse the basic block array placing edges. */
438 tree first = first_stmt (bb);
439 tree last = last_stmt (bb);
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. */
470 /* Create edges for control statement at basic block BB. */
473 make_ctrl_stmt_edges (basic_block bb)
475 tree last = last_stmt (bb);
478 switch (TREE_CODE (last))
481 make_goto_expr_edges (bb);
485 make_edge (bb, EXIT_BLOCK_PTR, 0);
489 make_cond_expr_edges (bb);
493 make_switch_expr_edges (bb);
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);
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. */
514 make_exit_edges (basic_block bb)
516 tree last = last_stmt (bb), op;
519 switch (TREE_CODE (last))
524 /* If this function receives a nonlocal goto, then we need to
525 make edges from this call site to all the nonlocal goto
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
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
542 if (call_expr_flags (last) & ECF_NORETURN)
544 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
548 /* Don't forget the fall-thru edge. */
549 make_edge (bb, bb->next_bb, EDGE_FALLTHRU);
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);
571 /* Create the edges for a COND_EXPR starting at block BB.
572 At this point, both clauses must contain only simple gotos. */
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;
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));
595 e->goto_locus = EXPR_LOCUS (COND_EXPR_THEN (entry));
597 e = make_edge (bb, else_bb, EDGE_FALSE_VALUE);
600 #ifdef USE_MAPPED_LOCATION
601 e->goto_locus = EXPR_LOCATION (COND_EXPR_ELSE (entry));
603 e->goto_locus = EXPR_LOCUS (COND_EXPR_ELSE (entry));
608 /* Hashing routine for EDGE_TO_CASES. */
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. */
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;
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
639 edge_to_cases_cleanup (void *p)
641 struct edge_to_cases_elt *elt = p;
644 for (t = elt->case_labels; t; t = next)
646 next = TREE_CHAIN (t);
647 TREE_CHAIN (t) = NULL;
652 /* Start recording information mapping edges to case labels. */
655 start_recording_case_labels (void)
657 gcc_assert (edge_to_cases == NULL);
659 edge_to_cases = htab_create (37,
662 edge_to_cases_cleanup);
665 /* Return nonzero if we are recording information for case labels. */
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. */
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. */
685 record_switch_edge (edge e, tree case_label)
687 struct edge_to_cases_elt *elt;
690 /* Build a hash table element so we can see if E is already
692 elt = xmalloc (sizeof (struct edge_to_cases_elt));
694 elt->case_labels = case_label;
696 slot = htab_find_slot (edge_to_cases, elt, INSERT);
700 /* E was not in the hash table. Install E into the hash table. */
705 /* E was already in the hash table. Free ELT as we do not need it
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. */
724 get_cases_for_edge (edge e, tree t)
726 struct edge_to_cases_elt elt, *elt_p;
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 ())
738 elt.case_labels = NULL;
739 slot = htab_find_slot (edge_to_cases, &elt, NO_INSERT);
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));
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. */
767 make_switch_expr_edges (basic_block bb)
769 tree entry = last_stmt (bb);
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. */
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));
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)
806 return VARRAY_BB (ifun->cfg->x_label_to_block_map, uid);
809 /* Create edges for a goto statement at block BB. */
812 make_goto_expr_edges (basic_block bb)
815 basic_block target_bb;
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)
828 tree dest = GOTO_DESTINATION (goto_t);
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);
838 e->goto_locus = EXPR_LOCUS (goto_t);
844 /* Nothing more to do for nonlocal gotos. */
845 if (TREE_CODE (dest) == LABEL_DECL)
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
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)
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
872 || (DECL_NONLOCAL (LABEL_EXPR_LABEL (target)) && for_call == 1))
874 make_edge (bb, target_bb, EDGE_ABNORMAL);
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 /*---------------------------------------------------------------------------
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
894 We only run this pass once, running it more than once is probably not
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. */
902 update_eh_label (struct eh_region *region)
904 tree old_label = get_eh_region_tree_label (region);
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. */
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. */
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. */
939 cleanup_dead_labels (void)
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. */
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)
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;
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;
979 /* Now redirect all jumps/branches to the selected label.
980 First do so for each block ending in a control statement. */
983 tree stmt = last_stmt (bb);
987 switch (TREE_CODE (stmt))
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));
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;
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. */
1023 if (! computed_goto_p (stmt))
1025 GOTO_DESTINATION (stmt)
1026 = main_block_label (GOTO_DESTINATION (stmt));
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. */
1041 block_stmt_iterator i;
1042 tree label_for_this_bb = label_for_bb[bb->index];
1044 if (! label_for_this_bb)
1047 for (i = bsi_start (bb); !bsi_end_p (i); )
1049 tree label, stmt = bsi_stmt (i);
1051 if (TREE_CODE (stmt) != LABEL_EXPR)
1054 label = LABEL_EXPR_LABEL (stmt);
1056 if (label == label_for_this_bb
1057 || ! DECL_ARTIFICIAL (label)
1058 || DECL_NONLOCAL (label))
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
1071 Eg. three separate entries 1: 2: 3: become one entry 1..3: */
1074 group_case_labels (void)
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);
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. */
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
1107 if (base_label == default_label)
1109 TREE_VEC_ELT (labels, i) = NULL_TREE;
1115 base_high = CASE_HIGH (base_case) ?
1116 CASE_HIGH (base_case) : CASE_LOW (base_case);
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;
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))
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. */
1161 tree_can_merge_blocks_p (basic_block a, basic_block b)
1164 block_stmt_iterator bsi;
1167 if (!single_succ_p (a))
1170 if (single_succ_edge (a)->flags & EDGE_ABNORMAL)
1173 if (single_succ (a) != b)
1176 if (!single_pred_p (b))
1179 if (b == EXIT_BLOCK_PTR)
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))
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)))
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);
1198 if (need_ssa_update_p ())
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)))
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)
1213 if (!DECL_ARTIFICIAL (LABEL_EXPR_LABEL (stmt)))
1217 /* Protect the loop latches. */
1219 && b->loop_father->latch == b)
1225 /* Replaces all uses of NAME by VAL. */
1228 replace_uses_by (tree name, tree val)
1230 imm_use_iterator imm_iter;
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);
1243 if (TREE_CODE (stmt) == PHI_NODE)
1245 e = PHI_ARG_EDGE (stmt, PHI_ARG_INDEX_FROM_USE (use));
1246 if (e->flags & EDGE_ABNORMAL)
1248 /* This can only occur for virtual operands, since
1249 for the real ones SSA_NAME_OCCURS_IN_ABNORMAL_PHI (name))
1250 would prevent replacement. */
1251 gcc_assert (!is_gimple_reg (name));
1252 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (val) = 1;
1256 VEC_safe_push (tree, heap, stmts, stmt);
1259 /* We do not update the statements in the loop above. Consider
1262 If we performed the update in the first loop, the statement
1263 would be rescanned after first occurrence of w is replaced,
1264 the new uses would be placed to the beginning of the list,
1265 and we would never process them. */
1266 for (i = 0; VEC_iterate (tree, stmts, i, stmt); i++)
1270 fold_stmt_inplace (stmt);
1272 rhs = get_rhs (stmt);
1273 if (TREE_CODE (rhs) == ADDR_EXPR)
1274 recompute_tree_invarant_for_addr_expr (rhs);
1279 VEC_free (tree, heap, stmts);
1281 /* Also update the trees stored in loop structures. */
1286 for (i = 0; i < current_loops->num; i++)
1288 loop = current_loops->parray[i];
1290 substitute_in_loop_info (loop, name, val);
1295 /* Merge block B into block A. */
1298 tree_merge_blocks (basic_block a, basic_block b)
1300 block_stmt_iterator bsi;
1301 tree_stmt_iterator last;
1305 fprintf (dump_file, "Merging blocks %d and %d\n", a->index, b->index);
1307 /* Remove the phi nodes. */
1309 for (phi = phi_nodes (b); phi; phi = phi_nodes (b))
1311 tree def = PHI_RESULT (phi), use = PHI_ARG_DEF (phi, 0);
1314 if (!may_propagate_copy (def, use)
1315 /* Propagating pointers might cause the set of vops for statements
1316 to be changed, and thus require ssa form update. */
1317 || (is_gimple_reg (def)
1318 && POINTER_TYPE_P (TREE_TYPE (def))))
1320 gcc_assert (is_gimple_reg (def));
1322 /* Note that just emitting the copies is fine -- there is no problem
1323 with ordering of phi nodes. This is because A is the single
1324 predecessor of B, therefore results of the phi nodes cannot
1325 appear as arguments of the phi nodes. */
1326 copy = build2 (MODIFY_EXPR, void_type_node, def, use);
1327 bsi_insert_after (&bsi, copy, BSI_NEW_STMT);
1328 SET_PHI_RESULT (phi, NULL_TREE);
1329 SSA_NAME_DEF_STMT (def) = copy;
1332 replace_uses_by (def, use);
1333 remove_phi_node (phi, NULL);
1336 /* Ensure that B follows A. */
1337 move_block_after (b, a);
1339 gcc_assert (single_succ_edge (a)->flags & EDGE_FALLTHRU);
1340 gcc_assert (!last_stmt (a) || !stmt_ends_bb_p (last_stmt (a)));
1342 /* Remove labels from B and set bb_for_stmt to A for other statements. */
1343 for (bsi = bsi_start (b); !bsi_end_p (bsi);)
1345 if (TREE_CODE (bsi_stmt (bsi)) == LABEL_EXPR)
1347 tree label = bsi_stmt (bsi);
1350 /* Now that we can thread computed gotos, we might have
1351 a situation where we have a forced label in block B
1352 However, the label at the start of block B might still be
1353 used in other ways (think about the runtime checking for
1354 Fortran assigned gotos). So we can not just delete the
1355 label. Instead we move the label to the start of block A. */
1356 if (FORCED_LABEL (LABEL_EXPR_LABEL (label)))
1358 block_stmt_iterator dest_bsi = bsi_start (a);
1359 bsi_insert_before (&dest_bsi, label, BSI_NEW_STMT);
1364 set_bb_for_stmt (bsi_stmt (bsi), a);
1369 /* Merge the chains. */
1370 last = tsi_last (a->stmt_list);
1371 tsi_link_after (&last, b->stmt_list, TSI_NEW_STMT);
1372 b->stmt_list = NULL;
1376 /* Walk the function tree removing unnecessary statements.
1378 * Empty statement nodes are removed
1380 * Unnecessary TRY_FINALLY and TRY_CATCH blocks are removed
1382 * Unnecessary COND_EXPRs are removed
1384 * Some unnecessary BIND_EXPRs are removed
1386 Clearly more work could be done. The trick is doing the analysis
1387 and removal fast enough to be a net improvement in compile times.
1389 Note that when we remove a control structure such as a COND_EXPR
1390 BIND_EXPR, or TRY block, we will need to repeat this optimization pass
1391 to ensure we eliminate all the useless code. */
1402 static void remove_useless_stmts_1 (tree *, struct rus_data *);
1405 remove_useless_stmts_warn_notreached (tree stmt)
1407 if (EXPR_HAS_LOCATION (stmt))
1409 location_t loc = EXPR_LOCATION (stmt);
1410 if (LOCATION_LINE (loc) > 0)
1412 warning (0, "%Hwill never be executed", &loc);
1417 switch (TREE_CODE (stmt))
1419 case STATEMENT_LIST:
1421 tree_stmt_iterator i;
1422 for (i = tsi_start (stmt); !tsi_end_p (i); tsi_next (&i))
1423 if (remove_useless_stmts_warn_notreached (tsi_stmt (i)))
1429 if (remove_useless_stmts_warn_notreached (COND_EXPR_COND (stmt)))
1431 if (remove_useless_stmts_warn_notreached (COND_EXPR_THEN (stmt)))
1433 if (remove_useless_stmts_warn_notreached (COND_EXPR_ELSE (stmt)))
1437 case TRY_FINALLY_EXPR:
1438 case TRY_CATCH_EXPR:
1439 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt, 0)))
1441 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt, 1)))
1446 return remove_useless_stmts_warn_notreached (CATCH_BODY (stmt));
1447 case EH_FILTER_EXPR:
1448 return remove_useless_stmts_warn_notreached (EH_FILTER_FAILURE (stmt));
1450 return remove_useless_stmts_warn_notreached (BIND_EXPR_BLOCK (stmt));
1453 /* Not a live container. */
1461 remove_useless_stmts_cond (tree *stmt_p, struct rus_data *data)
1463 tree then_clause, else_clause, cond;
1464 bool save_has_label, then_has_label, else_has_label;
1466 save_has_label = data->has_label;
1467 data->has_label = false;
1468 data->last_goto = NULL;
1470 remove_useless_stmts_1 (&COND_EXPR_THEN (*stmt_p), data);
1472 then_has_label = data->has_label;
1473 data->has_label = false;
1474 data->last_goto = NULL;
1476 remove_useless_stmts_1 (&COND_EXPR_ELSE (*stmt_p), data);
1478 else_has_label = data->has_label;
1479 data->has_label = save_has_label | then_has_label | else_has_label;
1481 then_clause = COND_EXPR_THEN (*stmt_p);
1482 else_clause = COND_EXPR_ELSE (*stmt_p);
1483 cond = fold (COND_EXPR_COND (*stmt_p));
1485 /* If neither arm does anything at all, we can remove the whole IF. */
1486 if (!TREE_SIDE_EFFECTS (then_clause) && !TREE_SIDE_EFFECTS (else_clause))
1488 *stmt_p = build_empty_stmt ();
1489 data->repeat = true;
1492 /* If there are no reachable statements in an arm, then we can
1493 zap the entire conditional. */
1494 else if (integer_nonzerop (cond) && !else_has_label)
1496 if (warn_notreached)
1497 remove_useless_stmts_warn_notreached (else_clause);
1498 *stmt_p = then_clause;
1499 data->repeat = true;
1501 else if (integer_zerop (cond) && !then_has_label)
1503 if (warn_notreached)
1504 remove_useless_stmts_warn_notreached (then_clause);
1505 *stmt_p = else_clause;
1506 data->repeat = true;
1509 /* Check a couple of simple things on then/else with single stmts. */
1512 tree then_stmt = expr_only (then_clause);
1513 tree else_stmt = expr_only (else_clause);
1515 /* Notice branches to a common destination. */
1516 if (then_stmt && else_stmt
1517 && TREE_CODE (then_stmt) == GOTO_EXPR
1518 && TREE_CODE (else_stmt) == GOTO_EXPR
1519 && (GOTO_DESTINATION (then_stmt) == GOTO_DESTINATION (else_stmt)))
1521 *stmt_p = then_stmt;
1522 data->repeat = true;
1525 /* If the THEN/ELSE clause merely assigns a value to a variable or
1526 parameter which is already known to contain that value, then
1527 remove the useless THEN/ELSE clause. */
1528 else if (TREE_CODE (cond) == VAR_DECL || TREE_CODE (cond) == PARM_DECL)
1531 && TREE_CODE (else_stmt) == MODIFY_EXPR
1532 && TREE_OPERAND (else_stmt, 0) == cond
1533 && integer_zerop (TREE_OPERAND (else_stmt, 1)))
1534 COND_EXPR_ELSE (*stmt_p) = alloc_stmt_list ();
1536 else if ((TREE_CODE (cond) == EQ_EXPR || TREE_CODE (cond) == NE_EXPR)
1537 && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL
1538 || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL)
1539 && TREE_CONSTANT (TREE_OPERAND (cond, 1)))
1541 tree stmt = (TREE_CODE (cond) == EQ_EXPR
1542 ? then_stmt : else_stmt);
1543 tree *location = (TREE_CODE (cond) == EQ_EXPR
1544 ? &COND_EXPR_THEN (*stmt_p)
1545 : &COND_EXPR_ELSE (*stmt_p));
1548 && TREE_CODE (stmt) == MODIFY_EXPR
1549 && TREE_OPERAND (stmt, 0) == TREE_OPERAND (cond, 0)
1550 && TREE_OPERAND (stmt, 1) == TREE_OPERAND (cond, 1))
1551 *location = alloc_stmt_list ();
1555 /* Protect GOTOs in the arm of COND_EXPRs from being removed. They
1556 would be re-introduced during lowering. */
1557 data->last_goto = NULL;
1562 remove_useless_stmts_tf (tree *stmt_p, struct rus_data *data)
1564 bool save_may_branch, save_may_throw;
1565 bool this_may_branch, this_may_throw;
1567 /* Collect may_branch and may_throw information for the body only. */
1568 save_may_branch = data->may_branch;
1569 save_may_throw = data->may_throw;
1570 data->may_branch = false;
1571 data->may_throw = false;
1572 data->last_goto = NULL;
1574 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 0), data);
1576 this_may_branch = data->may_branch;
1577 this_may_throw = data->may_throw;
1578 data->may_branch |= save_may_branch;
1579 data->may_throw |= save_may_throw;
1580 data->last_goto = NULL;
1582 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 1), data);
1584 /* If the body is empty, then we can emit the FINALLY block without
1585 the enclosing TRY_FINALLY_EXPR. */
1586 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 0)))
1588 *stmt_p = TREE_OPERAND (*stmt_p, 1);
1589 data->repeat = true;
1592 /* If the handler is empty, then we can emit the TRY block without
1593 the enclosing TRY_FINALLY_EXPR. */
1594 else if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 1)))
1596 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1597 data->repeat = true;
1600 /* If the body neither throws, nor branches, then we can safely
1601 string the TRY and FINALLY blocks together. */
1602 else if (!this_may_branch && !this_may_throw)
1604 tree stmt = *stmt_p;
1605 *stmt_p = TREE_OPERAND (stmt, 0);
1606 append_to_statement_list (TREE_OPERAND (stmt, 1), stmt_p);
1607 data->repeat = true;
1613 remove_useless_stmts_tc (tree *stmt_p, struct rus_data *data)
1615 bool save_may_throw, this_may_throw;
1616 tree_stmt_iterator i;
1619 /* Collect may_throw information for the body only. */
1620 save_may_throw = data->may_throw;
1621 data->may_throw = false;
1622 data->last_goto = NULL;
1624 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 0), data);
1626 this_may_throw = data->may_throw;
1627 data->may_throw = save_may_throw;
1629 /* If the body cannot throw, then we can drop the entire TRY_CATCH_EXPR. */
1630 if (!this_may_throw)
1632 if (warn_notreached)
1633 remove_useless_stmts_warn_notreached (TREE_OPERAND (*stmt_p, 1));
1634 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1635 data->repeat = true;
1639 /* Process the catch clause specially. We may be able to tell that
1640 no exceptions propagate past this point. */
1642 this_may_throw = true;
1643 i = tsi_start (TREE_OPERAND (*stmt_p, 1));
1644 stmt = tsi_stmt (i);
1645 data->last_goto = NULL;
1647 switch (TREE_CODE (stmt))
1650 for (; !tsi_end_p (i); tsi_next (&i))
1652 stmt = tsi_stmt (i);
1653 /* If we catch all exceptions, then the body does not
1654 propagate exceptions past this point. */
1655 if (CATCH_TYPES (stmt) == NULL)
1656 this_may_throw = false;
1657 data->last_goto = NULL;
1658 remove_useless_stmts_1 (&CATCH_BODY (stmt), data);
1662 case EH_FILTER_EXPR:
1663 if (EH_FILTER_MUST_NOT_THROW (stmt))
1664 this_may_throw = false;
1665 else if (EH_FILTER_TYPES (stmt) == NULL)
1666 this_may_throw = false;
1667 remove_useless_stmts_1 (&EH_FILTER_FAILURE (stmt), data);
1671 /* Otherwise this is a cleanup. */
1672 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 1), data);
1674 /* If the cleanup is empty, then we can emit the TRY block without
1675 the enclosing TRY_CATCH_EXPR. */
1676 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 1)))
1678 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1679 data->repeat = true;
1683 data->may_throw |= this_may_throw;
1688 remove_useless_stmts_bind (tree *stmt_p, struct rus_data *data)
1692 /* First remove anything underneath the BIND_EXPR. */
1693 remove_useless_stmts_1 (&BIND_EXPR_BODY (*stmt_p), data);
1695 /* If the BIND_EXPR has no variables, then we can pull everything
1696 up one level and remove the BIND_EXPR, unless this is the toplevel
1697 BIND_EXPR for the current function or an inlined function.
1699 When this situation occurs we will want to apply this
1700 optimization again. */
1701 block = BIND_EXPR_BLOCK (*stmt_p);
1702 if (BIND_EXPR_VARS (*stmt_p) == NULL_TREE
1703 && *stmt_p != DECL_SAVED_TREE (current_function_decl)
1705 || ! BLOCK_ABSTRACT_ORIGIN (block)
1706 || (TREE_CODE (BLOCK_ABSTRACT_ORIGIN (block))
1709 *stmt_p = BIND_EXPR_BODY (*stmt_p);
1710 data->repeat = true;
1716 remove_useless_stmts_goto (tree *stmt_p, struct rus_data *data)
1718 tree dest = GOTO_DESTINATION (*stmt_p);
1720 data->may_branch = true;
1721 data->last_goto = NULL;
1723 /* Record the last goto expr, so that we can delete it if unnecessary. */
1724 if (TREE_CODE (dest) == LABEL_DECL)
1725 data->last_goto = stmt_p;
1730 remove_useless_stmts_label (tree *stmt_p, struct rus_data *data)
1732 tree label = LABEL_EXPR_LABEL (*stmt_p);
1734 data->has_label = true;
1736 /* We do want to jump across non-local label receiver code. */
1737 if (DECL_NONLOCAL (label))
1738 data->last_goto = NULL;
1740 else if (data->last_goto && GOTO_DESTINATION (*data->last_goto) == label)
1742 *data->last_goto = build_empty_stmt ();
1743 data->repeat = true;
1746 /* ??? Add something here to delete unused labels. */
1750 /* If the function is "const" or "pure", then clear TREE_SIDE_EFFECTS on its
1751 decl. This allows us to eliminate redundant or useless
1752 calls to "const" functions.
1754 Gimplifier already does the same operation, but we may notice functions
1755 being const and pure once their calls has been gimplified, so we need
1756 to update the flag. */
1759 update_call_expr_flags (tree call)
1761 tree decl = get_callee_fndecl (call);
1764 if (call_expr_flags (call) & (ECF_CONST | ECF_PURE))
1765 TREE_SIDE_EFFECTS (call) = 0;
1766 if (TREE_NOTHROW (decl))
1767 TREE_NOTHROW (call) = 1;
1771 /* T is CALL_EXPR. Set current_function_calls_* flags. */
1774 notice_special_calls (tree t)
1776 int flags = call_expr_flags (t);
1778 if (flags & ECF_MAY_BE_ALLOCA)
1779 current_function_calls_alloca = true;
1780 if (flags & ECF_RETURNS_TWICE)
1781 current_function_calls_setjmp = true;
1785 /* Clear flags set by notice_special_calls. Used by dead code removal
1786 to update the flags. */
1789 clear_special_calls (void)
1791 current_function_calls_alloca = false;
1792 current_function_calls_setjmp = false;
1797 remove_useless_stmts_1 (tree *tp, struct rus_data *data)
1801 switch (TREE_CODE (t))
1804 remove_useless_stmts_cond (tp, data);
1807 case TRY_FINALLY_EXPR:
1808 remove_useless_stmts_tf (tp, data);
1811 case TRY_CATCH_EXPR:
1812 remove_useless_stmts_tc (tp, data);
1816 remove_useless_stmts_bind (tp, data);
1820 remove_useless_stmts_goto (tp, data);
1824 remove_useless_stmts_label (tp, data);
1829 data->last_goto = NULL;
1830 data->may_branch = true;
1835 data->last_goto = NULL;
1836 notice_special_calls (t);
1837 update_call_expr_flags (t);
1838 if (tree_could_throw_p (t))
1839 data->may_throw = true;
1843 data->last_goto = NULL;
1845 op = get_call_expr_in (t);
1848 update_call_expr_flags (op);
1849 notice_special_calls (op);
1851 if (tree_could_throw_p (t))
1852 data->may_throw = true;
1855 case STATEMENT_LIST:
1857 tree_stmt_iterator i = tsi_start (t);
1858 while (!tsi_end_p (i))
1861 if (IS_EMPTY_STMT (t))
1867 remove_useless_stmts_1 (tsi_stmt_ptr (i), data);
1870 if (TREE_CODE (t) == STATEMENT_LIST)
1872 tsi_link_before (&i, t, TSI_SAME_STMT);
1882 data->last_goto = NULL;
1886 data->last_goto = NULL;
1892 remove_useless_stmts (void)
1894 struct rus_data data;
1896 clear_special_calls ();
1900 memset (&data, 0, sizeof (data));
1901 remove_useless_stmts_1 (&DECL_SAVED_TREE (current_function_decl), &data);
1903 while (data.repeat);
1907 struct tree_opt_pass pass_remove_useless_stmts =
1909 "useless", /* name */
1911 remove_useless_stmts, /* execute */
1914 0, /* static_pass_number */
1916 PROP_gimple_any, /* properties_required */
1917 0, /* properties_provided */
1918 0, /* properties_destroyed */
1919 0, /* todo_flags_start */
1920 TODO_dump_func, /* todo_flags_finish */
1924 /* Remove PHI nodes associated with basic block BB and all edges out of BB. */
1927 remove_phi_nodes_and_edges_for_unreachable_block (basic_block bb)
1931 /* Since this block is no longer reachable, we can just delete all
1932 of its PHI nodes. */
1933 phi = phi_nodes (bb);
1936 tree next = PHI_CHAIN (phi);
1937 remove_phi_node (phi, NULL_TREE);
1941 /* Remove edges to BB's successors. */
1942 while (EDGE_COUNT (bb->succs) > 0)
1943 remove_edge (EDGE_SUCC (bb, 0));
1947 /* Remove statements of basic block BB. */
1950 remove_bb (basic_block bb)
1952 block_stmt_iterator i;
1953 #ifdef USE_MAPPED_LOCATION
1954 source_location loc = UNKNOWN_LOCATION;
1956 source_locus loc = 0;
1961 fprintf (dump_file, "Removing basic block %d\n", bb->index);
1962 if (dump_flags & TDF_DETAILS)
1964 dump_bb (bb, dump_file, 0);
1965 fprintf (dump_file, "\n");
1969 /* If we remove the header or the latch of a loop, mark the loop for
1970 removal by setting its header and latch to NULL. */
1973 struct loop *loop = bb->loop_father;
1975 if (loop->latch == bb
1976 || loop->header == bb)
1979 loop->header = NULL;
1983 /* Remove all the instructions in the block. */
1984 for (i = bsi_start (bb); !bsi_end_p (i);)
1986 tree stmt = bsi_stmt (i);
1987 if (TREE_CODE (stmt) == LABEL_EXPR
1988 && FORCED_LABEL (LABEL_EXPR_LABEL (stmt)))
1990 basic_block new_bb = bb->prev_bb;
1991 block_stmt_iterator new_bsi = bsi_start (new_bb);
1994 bsi_insert_before (&new_bsi, stmt, BSI_NEW_STMT);
1998 /* Release SSA definitions if we are in SSA. Note that we
1999 may be called when not in SSA. For example,
2000 final_cleanup calls this function via
2001 cleanup_tree_cfg. */
2003 release_defs (stmt);
2008 /* Don't warn for removed gotos. Gotos are often removed due to
2009 jump threading, thus resulting in bogus warnings. Not great,
2010 since this way we lose warnings for gotos in the original
2011 program that are indeed unreachable. */
2012 if (TREE_CODE (stmt) != GOTO_EXPR && EXPR_HAS_LOCATION (stmt) && !loc)
2014 #ifdef USE_MAPPED_LOCATION
2015 if (EXPR_HAS_LOCATION (stmt))
2016 loc = EXPR_LOCATION (stmt);
2019 t = EXPR_LOCUS (stmt);
2020 if (t && LOCATION_LINE (*t) > 0)
2026 /* If requested, give a warning that the first statement in the
2027 block is unreachable. We walk statements backwards in the
2028 loop above, so the last statement we process is the first statement
2030 #ifdef USE_MAPPED_LOCATION
2031 if (loc > BUILTINS_LOCATION)
2032 warning (OPT_Wunreachable_code, "%Hwill never be executed", &loc);
2035 warning (OPT_Wunreachable_code, "%Hwill never be executed", loc);
2038 remove_phi_nodes_and_edges_for_unreachable_block (bb);
2042 /* Given a basic block BB ending with COND_EXPR or SWITCH_EXPR, and a
2043 predicate VAL, return the edge that will be taken out of the block.
2044 If VAL does not match a unique edge, NULL is returned. */
2047 find_taken_edge (basic_block bb, tree val)
2051 stmt = last_stmt (bb);
2054 gcc_assert (is_ctrl_stmt (stmt));
2057 if (! is_gimple_min_invariant (val))
2060 if (TREE_CODE (stmt) == COND_EXPR)
2061 return find_taken_edge_cond_expr (bb, val);
2063 if (TREE_CODE (stmt) == SWITCH_EXPR)
2064 return find_taken_edge_switch_expr (bb, val);
2066 if (computed_goto_p (stmt))
2067 return find_taken_edge_computed_goto (bb, TREE_OPERAND( val, 0));
2072 /* Given a constant value VAL and the entry block BB to a GOTO_EXPR
2073 statement, determine which of the outgoing edges will be taken out of the
2074 block. Return NULL if either edge may be taken. */
2077 find_taken_edge_computed_goto (basic_block bb, tree val)
2082 dest = label_to_block (val);
2085 e = find_edge (bb, dest);
2086 gcc_assert (e != NULL);
2092 /* Given a constant value VAL and the entry block BB to a COND_EXPR
2093 statement, determine which of the two edges will be taken out of the
2094 block. Return NULL if either edge may be taken. */
2097 find_taken_edge_cond_expr (basic_block bb, tree val)
2099 edge true_edge, false_edge;
2101 extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
2103 gcc_assert (TREE_CODE (val) == INTEGER_CST);
2104 return (zero_p (val) ? false_edge : true_edge);
2107 /* Given an INTEGER_CST VAL and the entry block BB to a SWITCH_EXPR
2108 statement, determine which edge will be taken out of the block. Return
2109 NULL if any edge may be taken. */
2112 find_taken_edge_switch_expr (basic_block bb, tree val)
2114 tree switch_expr, taken_case;
2115 basic_block dest_bb;
2118 switch_expr = last_stmt (bb);
2119 taken_case = find_case_label_for_value (switch_expr, val);
2120 dest_bb = label_to_block (CASE_LABEL (taken_case));
2122 e = find_edge (bb, dest_bb);
2128 /* Return the CASE_LABEL_EXPR that SWITCH_EXPR will take for VAL.
2129 We can make optimal use here of the fact that the case labels are
2130 sorted: We can do a binary search for a case matching VAL. */
2133 find_case_label_for_value (tree switch_expr, tree val)
2135 tree vec = SWITCH_LABELS (switch_expr);
2136 size_t low, high, n = TREE_VEC_LENGTH (vec);
2137 tree default_case = TREE_VEC_ELT (vec, n - 1);
2139 for (low = -1, high = n - 1; high - low > 1; )
2141 size_t i = (high + low) / 2;
2142 tree t = TREE_VEC_ELT (vec, i);
2145 /* Cache the result of comparing CASE_LOW and val. */
2146 cmp = tree_int_cst_compare (CASE_LOW (t), val);
2153 if (CASE_HIGH (t) == NULL)
2155 /* A singe-valued case label. */
2161 /* A case range. We can only handle integer ranges. */
2162 if (cmp <= 0 && tree_int_cst_compare (CASE_HIGH (t), val) >= 0)
2167 return default_case;
2173 /*---------------------------------------------------------------------------
2175 ---------------------------------------------------------------------------*/
2177 /* Dump tree-specific information of block BB to file OUTF. */
2180 tree_dump_bb (basic_block bb, FILE *outf, int indent)
2182 dump_generic_bb (outf, bb, indent, TDF_VOPS);
2186 /* Dump a basic block on stderr. */
2189 debug_tree_bb (basic_block bb)
2191 dump_bb (bb, stderr, 0);
2195 /* Dump basic block with index N on stderr. */
2198 debug_tree_bb_n (int n)
2200 debug_tree_bb (BASIC_BLOCK (n));
2201 return BASIC_BLOCK (n);
2205 /* Dump the CFG on stderr.
2207 FLAGS are the same used by the tree dumping functions
2208 (see TDF_* in tree.h). */
2211 debug_tree_cfg (int flags)
2213 dump_tree_cfg (stderr, flags);
2217 /* Dump the program showing basic block boundaries on the given FILE.
2219 FLAGS are the same used by the tree dumping functions (see TDF_* in
2223 dump_tree_cfg (FILE *file, int flags)
2225 if (flags & TDF_DETAILS)
2227 const char *funcname
2228 = lang_hooks.decl_printable_name (current_function_decl, 2);
2231 fprintf (file, ";; Function %s\n\n", funcname);
2232 fprintf (file, ";; \n%d basic blocks, %d edges, last basic block %d.\n\n",
2233 n_basic_blocks, n_edges, last_basic_block);
2235 brief_dump_cfg (file);
2236 fprintf (file, "\n");
2239 if (flags & TDF_STATS)
2240 dump_cfg_stats (file);
2242 dump_function_to_file (current_function_decl, file, flags | TDF_BLOCKS);
2246 /* Dump CFG statistics on FILE. */
2249 dump_cfg_stats (FILE *file)
2251 static long max_num_merged_labels = 0;
2252 unsigned long size, total = 0;
2255 const char * const fmt_str = "%-30s%-13s%12s\n";
2256 const char * const fmt_str_1 = "%-30s%13d%11lu%c\n";
2257 const char * const fmt_str_2 = "%-30s%13ld%11lu%c\n";
2258 const char * const fmt_str_3 = "%-43s%11lu%c\n";
2259 const char *funcname
2260 = lang_hooks.decl_printable_name (current_function_decl, 2);
2263 fprintf (file, "\nCFG Statistics for %s\n\n", funcname);
2265 fprintf (file, "---------------------------------------------------------\n");
2266 fprintf (file, fmt_str, "", " Number of ", "Memory");
2267 fprintf (file, fmt_str, "", " instances ", "used ");
2268 fprintf (file, "---------------------------------------------------------\n");
2270 size = n_basic_blocks * sizeof (struct basic_block_def);
2272 fprintf (file, fmt_str_1, "Basic blocks", n_basic_blocks,
2273 SCALE (size), LABEL (size));
2277 num_edges += EDGE_COUNT (bb->succs);
2278 size = num_edges * sizeof (struct edge_def);
2280 fprintf (file, fmt_str_2, "Edges", num_edges, SCALE (size), LABEL (size));
2282 fprintf (file, "---------------------------------------------------------\n");
2283 fprintf (file, fmt_str_3, "Total memory used by CFG data", SCALE (total),
2285 fprintf (file, "---------------------------------------------------------\n");
2286 fprintf (file, "\n");
2288 if (cfg_stats.num_merged_labels > max_num_merged_labels)
2289 max_num_merged_labels = cfg_stats.num_merged_labels;
2291 fprintf (file, "Coalesced label blocks: %ld (Max so far: %ld)\n",
2292 cfg_stats.num_merged_labels, max_num_merged_labels);
2294 fprintf (file, "\n");
2298 /* Dump CFG statistics on stderr. Keep extern so that it's always
2299 linked in the final executable. */
2302 debug_cfg_stats (void)
2304 dump_cfg_stats (stderr);
2308 /* Dump the flowgraph to a .vcg FILE. */
2311 tree_cfg2vcg (FILE *file)
2316 const char *funcname
2317 = lang_hooks.decl_printable_name (current_function_decl, 2);
2319 /* Write the file header. */
2320 fprintf (file, "graph: { title: \"%s\"\n", funcname);
2321 fprintf (file, "node: { title: \"ENTRY\" label: \"ENTRY\" }\n");
2322 fprintf (file, "node: { title: \"EXIT\" label: \"EXIT\" }\n");
2324 /* Write blocks and edges. */
2325 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
2327 fprintf (file, "edge: { sourcename: \"ENTRY\" targetname: \"%d\"",
2330 if (e->flags & EDGE_FAKE)
2331 fprintf (file, " linestyle: dotted priority: 10");
2333 fprintf (file, " linestyle: solid priority: 100");
2335 fprintf (file, " }\n");
2341 enum tree_code head_code, end_code;
2342 const char *head_name, *end_name;
2345 tree first = first_stmt (bb);
2346 tree last = last_stmt (bb);
2350 head_code = TREE_CODE (first);
2351 head_name = tree_code_name[head_code];
2352 head_line = get_lineno (first);
2355 head_name = "no-statement";
2359 end_code = TREE_CODE (last);
2360 end_name = tree_code_name[end_code];
2361 end_line = get_lineno (last);
2364 end_name = "no-statement";
2366 fprintf (file, "node: { title: \"%d\" label: \"#%d\\n%s (%d)\\n%s (%d)\"}\n",
2367 bb->index, bb->index, head_name, head_line, end_name,
2370 FOR_EACH_EDGE (e, ei, bb->succs)
2372 if (e->dest == EXIT_BLOCK_PTR)
2373 fprintf (file, "edge: { sourcename: \"%d\" targetname: \"EXIT\"", bb->index);
2375 fprintf (file, "edge: { sourcename: \"%d\" targetname: \"%d\"", bb->index, e->dest->index);
2377 if (e->flags & EDGE_FAKE)
2378 fprintf (file, " priority: 10 linestyle: dotted");
2380 fprintf (file, " priority: 100 linestyle: solid");
2382 fprintf (file, " }\n");
2385 if (bb->next_bb != EXIT_BLOCK_PTR)
2389 fputs ("}\n\n", file);
2394 /*---------------------------------------------------------------------------
2395 Miscellaneous helpers
2396 ---------------------------------------------------------------------------*/
2398 /* Return true if T represents a stmt that always transfers control. */
2401 is_ctrl_stmt (tree t)
2403 return (TREE_CODE (t) == COND_EXPR
2404 || TREE_CODE (t) == SWITCH_EXPR
2405 || TREE_CODE (t) == GOTO_EXPR
2406 || TREE_CODE (t) == RETURN_EXPR
2407 || TREE_CODE (t) == RESX_EXPR);
2411 /* Return true if T is a statement that may alter the flow of control
2412 (e.g., a call to a non-returning function). */
2415 is_ctrl_altering_stmt (tree t)
2420 call = get_call_expr_in (t);
2423 /* A non-pure/const CALL_EXPR alters flow control if the current
2424 function has nonlocal labels. */
2425 if (TREE_SIDE_EFFECTS (call) && current_function_has_nonlocal_label)
2428 /* A CALL_EXPR also alters control flow if it does not return. */
2429 if (call_expr_flags (call) & ECF_NORETURN)
2433 /* If a statement can throw, it alters control flow. */
2434 return tree_can_throw_internal (t);
2438 /* Return true if T is a computed goto. */
2441 computed_goto_p (tree t)
2443 return (TREE_CODE (t) == GOTO_EXPR
2444 && TREE_CODE (GOTO_DESTINATION (t)) != LABEL_DECL);
2448 /* Checks whether EXPR is a simple local goto. */
2451 simple_goto_p (tree expr)
2453 return (TREE_CODE (expr) == GOTO_EXPR
2454 && TREE_CODE (GOTO_DESTINATION (expr)) == LABEL_DECL);
2458 /* Return true if T should start a new basic block. PREV_T is the
2459 statement preceding T. It is used when T is a label or a case label.
2460 Labels should only start a new basic block if their previous statement
2461 wasn't a label. Otherwise, sequence of labels would generate
2462 unnecessary basic blocks that only contain a single label. */
2465 stmt_starts_bb_p (tree t, tree prev_t)
2470 /* LABEL_EXPRs start a new basic block only if the preceding
2471 statement wasn't a label of the same type. This prevents the
2472 creation of consecutive blocks that have nothing but a single
2474 if (TREE_CODE (t) == LABEL_EXPR)
2476 /* Nonlocal and computed GOTO targets always start a new block. */
2477 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (t))
2478 || FORCED_LABEL (LABEL_EXPR_LABEL (t)))
2481 if (prev_t && TREE_CODE (prev_t) == LABEL_EXPR)
2483 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (prev_t)))
2486 cfg_stats.num_merged_labels++;
2497 /* Return true if T should end a basic block. */
2500 stmt_ends_bb_p (tree t)
2502 return is_ctrl_stmt (t) || is_ctrl_altering_stmt (t);
2506 /* Add gotos that used to be represented implicitly in the CFG. */
2509 disband_implicit_edges (void)
2512 block_stmt_iterator last;
2519 last = bsi_last (bb);
2520 stmt = last_stmt (bb);
2522 if (stmt && TREE_CODE (stmt) == COND_EXPR)
2524 /* Remove superfluous gotos from COND_EXPR branches. Moved
2525 from cfg_remove_useless_stmts here since it violates the
2526 invariants for tree--cfg correspondence and thus fits better
2527 here where we do it anyway. */
2528 e = find_edge (bb, bb->next_bb);
2531 if (e->flags & EDGE_TRUE_VALUE)
2532 COND_EXPR_THEN (stmt) = build_empty_stmt ();
2533 else if (e->flags & EDGE_FALSE_VALUE)
2534 COND_EXPR_ELSE (stmt) = build_empty_stmt ();
2537 e->flags |= EDGE_FALLTHRU;
2543 if (stmt && TREE_CODE (stmt) == RETURN_EXPR)
2545 /* Remove the RETURN_EXPR if we may fall though to the exit
2547 gcc_assert (single_succ_p (bb));
2548 gcc_assert (single_succ (bb) == EXIT_BLOCK_PTR);
2550 if (bb->next_bb == EXIT_BLOCK_PTR
2551 && !TREE_OPERAND (stmt, 0))
2554 single_succ_edge (bb)->flags |= EDGE_FALLTHRU;
2559 /* There can be no fallthru edge if the last statement is a control
2561 if (stmt && is_ctrl_stmt (stmt))
2564 /* Find a fallthru edge and emit the goto if necessary. */
2565 FOR_EACH_EDGE (e, ei, bb->succs)
2566 if (e->flags & EDGE_FALLTHRU)
2569 if (!e || e->dest == bb->next_bb)
2572 gcc_assert (e->dest != EXIT_BLOCK_PTR);
2573 label = tree_block_label (e->dest);
2575 stmt = build1 (GOTO_EXPR, void_type_node, label);
2576 #ifdef USE_MAPPED_LOCATION
2577 SET_EXPR_LOCATION (stmt, e->goto_locus);
2579 SET_EXPR_LOCUS (stmt, e->goto_locus);
2581 bsi_insert_after (&last, stmt, BSI_NEW_STMT);
2582 e->flags &= ~EDGE_FALLTHRU;
2586 /* Remove block annotations and other datastructures. */
2589 delete_tree_cfg_annotations (void)
2591 label_to_block_map = NULL;
2595 /* Return the first statement in basic block BB. */
2598 first_stmt (basic_block bb)
2600 block_stmt_iterator i = bsi_start (bb);
2601 return !bsi_end_p (i) ? bsi_stmt (i) : NULL_TREE;
2605 /* Return the last statement in basic block BB. */
2608 last_stmt (basic_block bb)
2610 block_stmt_iterator b = bsi_last (bb);
2611 return !bsi_end_p (b) ? bsi_stmt (b) : NULL_TREE;
2615 /* Return a pointer to the last statement in block BB. */
2618 last_stmt_ptr (basic_block bb)
2620 block_stmt_iterator last = bsi_last (bb);
2621 return !bsi_end_p (last) ? bsi_stmt_ptr (last) : NULL;
2625 /* Return the last statement of an otherwise empty block. Return NULL
2626 if the block is totally empty, or if it contains more than one
2630 last_and_only_stmt (basic_block bb)
2632 block_stmt_iterator i = bsi_last (bb);
2638 last = bsi_stmt (i);
2643 /* Empty statements should no longer appear in the instruction stream.
2644 Everything that might have appeared before should be deleted by
2645 remove_useless_stmts, and the optimizers should just bsi_remove
2646 instead of smashing with build_empty_stmt.
2648 Thus the only thing that should appear here in a block containing
2649 one executable statement is a label. */
2650 prev = bsi_stmt (i);
2651 if (TREE_CODE (prev) == LABEL_EXPR)
2658 /* Mark BB as the basic block holding statement T. */
2661 set_bb_for_stmt (tree t, basic_block bb)
2663 if (TREE_CODE (t) == PHI_NODE)
2665 else if (TREE_CODE (t) == STATEMENT_LIST)
2667 tree_stmt_iterator i;
2668 for (i = tsi_start (t); !tsi_end_p (i); tsi_next (&i))
2669 set_bb_for_stmt (tsi_stmt (i), bb);
2673 stmt_ann_t ann = get_stmt_ann (t);
2676 /* If the statement is a label, add the label to block-to-labels map
2677 so that we can speed up edge creation for GOTO_EXPRs. */
2678 if (TREE_CODE (t) == LABEL_EXPR)
2682 t = LABEL_EXPR_LABEL (t);
2683 uid = LABEL_DECL_UID (t);
2686 LABEL_DECL_UID (t) = uid = cfun->last_label_uid++;
2687 if (VARRAY_SIZE (label_to_block_map) <= (unsigned) uid)
2688 VARRAY_GROW (label_to_block_map, 3 * uid / 2);
2691 /* We're moving an existing label. Make sure that we've
2692 removed it from the old block. */
2693 gcc_assert (!bb || !VARRAY_BB (label_to_block_map, uid));
2694 VARRAY_BB (label_to_block_map, uid) = bb;
2699 /* Finds iterator for STMT. */
2701 extern block_stmt_iterator
2702 bsi_for_stmt (tree stmt)
2704 block_stmt_iterator bsi;
2706 for (bsi = bsi_start (bb_for_stmt (stmt)); !bsi_end_p (bsi); bsi_next (&bsi))
2707 if (bsi_stmt (bsi) == stmt)
2713 /* Mark statement T as modified, and update it. */
2715 update_modified_stmts (tree t)
2717 if (TREE_CODE (t) == STATEMENT_LIST)
2719 tree_stmt_iterator i;
2721 for (i = tsi_start (t); !tsi_end_p (i); tsi_next (&i))
2723 stmt = tsi_stmt (i);
2724 update_stmt_if_modified (stmt);
2728 update_stmt_if_modified (t);
2731 /* Insert statement (or statement list) T before the statement
2732 pointed-to by iterator I. M specifies how to update iterator I
2733 after insertion (see enum bsi_iterator_update). */
2736 bsi_insert_before (block_stmt_iterator *i, tree t, enum bsi_iterator_update m)
2738 set_bb_for_stmt (t, i->bb);
2739 update_modified_stmts (t);
2740 tsi_link_before (&i->tsi, t, m);
2744 /* Insert statement (or statement list) T after the statement
2745 pointed-to by iterator I. M specifies how to update iterator I
2746 after insertion (see enum bsi_iterator_update). */
2749 bsi_insert_after (block_stmt_iterator *i, tree t, enum bsi_iterator_update m)
2751 set_bb_for_stmt (t, i->bb);
2752 update_modified_stmts (t);
2753 tsi_link_after (&i->tsi, t, m);
2757 /* Remove the statement pointed to by iterator I. The iterator is updated
2758 to the next statement. */
2761 bsi_remove (block_stmt_iterator *i)
2763 tree t = bsi_stmt (*i);
2764 set_bb_for_stmt (t, NULL);
2765 delink_stmt_imm_use (t);
2766 tsi_delink (&i->tsi);
2767 mark_stmt_modified (t);
2771 /* Move the statement at FROM so it comes right after the statement at TO. */
2774 bsi_move_after (block_stmt_iterator *from, block_stmt_iterator *to)
2776 tree stmt = bsi_stmt (*from);
2778 bsi_insert_after (to, stmt, BSI_SAME_STMT);
2782 /* Move the statement at FROM so it comes right before the statement at TO. */
2785 bsi_move_before (block_stmt_iterator *from, block_stmt_iterator *to)
2787 tree stmt = bsi_stmt (*from);
2789 bsi_insert_before (to, stmt, BSI_SAME_STMT);
2793 /* Move the statement at FROM to the end of basic block BB. */
2796 bsi_move_to_bb_end (block_stmt_iterator *from, basic_block bb)
2798 block_stmt_iterator last = bsi_last (bb);
2800 /* Have to check bsi_end_p because it could be an empty block. */
2801 if (!bsi_end_p (last) && is_ctrl_stmt (bsi_stmt (last)))
2802 bsi_move_before (from, &last);
2804 bsi_move_after (from, &last);
2808 /* Replace the contents of the statement pointed to by iterator BSI
2809 with STMT. If PRESERVE_EH_INFO is true, the exception handling
2810 information of the original statement is preserved. */
2813 bsi_replace (const block_stmt_iterator *bsi, tree stmt, bool preserve_eh_info)
2816 tree orig_stmt = bsi_stmt (*bsi);
2818 SET_EXPR_LOCUS (stmt, EXPR_LOCUS (orig_stmt));
2819 set_bb_for_stmt (stmt, bsi->bb);
2821 /* Preserve EH region information from the original statement, if
2822 requested by the caller. */
2823 if (preserve_eh_info)
2825 eh_region = lookup_stmt_eh_region (orig_stmt);
2827 add_stmt_to_eh_region (stmt, eh_region);
2830 delink_stmt_imm_use (orig_stmt);
2831 *bsi_stmt_ptr (*bsi) = stmt;
2832 mark_stmt_modified (stmt);
2833 update_modified_stmts (stmt);
2837 /* Insert the statement pointed-to by BSI into edge E. Every attempt
2838 is made to place the statement in an existing basic block, but
2839 sometimes that isn't possible. When it isn't possible, the edge is
2840 split and the statement is added to the new block.
2842 In all cases, the returned *BSI points to the correct location. The
2843 return value is true if insertion should be done after the location,
2844 or false if it should be done before the location. If new basic block
2845 has to be created, it is stored in *NEW_BB. */
2848 tree_find_edge_insert_loc (edge e, block_stmt_iterator *bsi,
2849 basic_block *new_bb)
2851 basic_block dest, src;
2857 /* If the destination has one predecessor which has no PHI nodes,
2858 insert there. Except for the exit block.
2860 The requirement for no PHI nodes could be relaxed. Basically we
2861 would have to examine the PHIs to prove that none of them used
2862 the value set by the statement we want to insert on E. That
2863 hardly seems worth the effort. */
2864 if (single_pred_p (dest)
2865 && ! phi_nodes (dest)
2866 && dest != EXIT_BLOCK_PTR)
2868 *bsi = bsi_start (dest);
2869 if (bsi_end_p (*bsi))
2872 /* Make sure we insert after any leading labels. */
2873 tmp = bsi_stmt (*bsi);
2874 while (TREE_CODE (tmp) == LABEL_EXPR)
2877 if (bsi_end_p (*bsi))
2879 tmp = bsi_stmt (*bsi);
2882 if (bsi_end_p (*bsi))
2884 *bsi = bsi_last (dest);
2891 /* If the source has one successor, the edge is not abnormal and
2892 the last statement does not end a basic block, insert there.
2893 Except for the entry block. */
2895 if ((e->flags & EDGE_ABNORMAL) == 0
2896 && single_succ_p (src)
2897 && src != ENTRY_BLOCK_PTR)
2899 *bsi = bsi_last (src);
2900 if (bsi_end_p (*bsi))
2903 tmp = bsi_stmt (*bsi);
2904 if (!stmt_ends_bb_p (tmp))
2907 /* Insert code just before returning the value. We may need to decompose
2908 the return in the case it contains non-trivial operand. */
2909 if (TREE_CODE (tmp) == RETURN_EXPR)
2911 tree op = TREE_OPERAND (tmp, 0);
2912 if (!is_gimple_val (op))
2914 gcc_assert (TREE_CODE (op) == MODIFY_EXPR);
2915 bsi_insert_before (bsi, op, BSI_NEW_STMT);
2916 TREE_OPERAND (tmp, 0) = TREE_OPERAND (op, 0);
2923 /* Otherwise, create a new basic block, and split this edge. */
2924 dest = split_edge (e);
2927 e = single_pred_edge (dest);
2932 /* This routine will commit all pending edge insertions, creating any new
2933 basic blocks which are necessary. */
2936 bsi_commit_edge_inserts (void)
2942 bsi_commit_one_edge_insert (single_succ_edge (ENTRY_BLOCK_PTR), NULL);
2945 FOR_EACH_EDGE (e, ei, bb->succs)
2946 bsi_commit_one_edge_insert (e, NULL);
2950 /* Commit insertions pending at edge E. If a new block is created, set NEW_BB
2951 to this block, otherwise set it to NULL. */
2954 bsi_commit_one_edge_insert (edge e, basic_block *new_bb)
2958 if (PENDING_STMT (e))
2960 block_stmt_iterator bsi;
2961 tree stmt = PENDING_STMT (e);
2963 PENDING_STMT (e) = NULL_TREE;
2965 if (tree_find_edge_insert_loc (e, &bsi, new_bb))
2966 bsi_insert_after (&bsi, stmt, BSI_NEW_STMT);
2968 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
2973 /* Add STMT to the pending list of edge E. No actual insertion is
2974 made until a call to bsi_commit_edge_inserts () is made. */
2977 bsi_insert_on_edge (edge e, tree stmt)
2979 append_to_statement_list (stmt, &PENDING_STMT (e));
2982 /* Similar to bsi_insert_on_edge+bsi_commit_edge_inserts. If a new
2983 block has to be created, it is returned. */
2986 bsi_insert_on_edge_immediate (edge e, tree stmt)
2988 block_stmt_iterator bsi;
2989 basic_block new_bb = NULL;
2991 gcc_assert (!PENDING_STMT (e));
2993 if (tree_find_edge_insert_loc (e, &bsi, &new_bb))
2994 bsi_insert_after (&bsi, stmt, BSI_NEW_STMT);
2996 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
3001 /*---------------------------------------------------------------------------
3002 Tree specific functions for CFG manipulation
3003 ---------------------------------------------------------------------------*/
3005 /* Reinstall those PHI arguments queued in OLD_EDGE to NEW_EDGE. */
3008 reinstall_phi_args (edge new_edge, edge old_edge)
3012 if (!PENDING_STMT (old_edge))
3015 for (var = PENDING_STMT (old_edge), phi = phi_nodes (new_edge->dest);
3017 var = TREE_CHAIN (var), phi = PHI_CHAIN (phi))
3019 tree result = TREE_PURPOSE (var);
3020 tree arg = TREE_VALUE (var);
3022 gcc_assert (result == PHI_RESULT (phi));
3024 add_phi_arg (phi, arg, new_edge);
3027 PENDING_STMT (old_edge) = NULL;
3030 /* Split a (typically critical) edge EDGE_IN. Return the new block.
3031 Abort on abnormal edges. */
3034 tree_split_edge (edge edge_in)
3036 basic_block new_bb, after_bb, dest, src;
3039 /* Abnormal edges cannot be split. */
3040 gcc_assert (!(edge_in->flags & EDGE_ABNORMAL));
3043 dest = edge_in->dest;
3045 /* Place the new block in the block list. Try to keep the new block
3046 near its "logical" location. This is of most help to humans looking
3047 at debugging dumps. */
3048 if (dest->prev_bb && find_edge (dest->prev_bb, dest))
3049 after_bb = edge_in->src;
3051 after_bb = dest->prev_bb;
3053 new_bb = create_empty_bb (after_bb);
3054 new_bb->frequency = EDGE_FREQUENCY (edge_in);
3055 new_bb->count = edge_in->count;
3056 new_edge = make_edge (new_bb, dest, EDGE_FALLTHRU);
3057 new_edge->probability = REG_BR_PROB_BASE;
3058 new_edge->count = edge_in->count;
3060 e = redirect_edge_and_branch (edge_in, new_bb);
3062 reinstall_phi_args (new_edge, e);
3068 /* Return true when BB has label LABEL in it. */
3071 has_label_p (basic_block bb, tree label)
3073 block_stmt_iterator bsi;
3075 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3077 tree stmt = bsi_stmt (bsi);
3079 if (TREE_CODE (stmt) != LABEL_EXPR)
3081 if (LABEL_EXPR_LABEL (stmt) == label)
3088 /* Callback for walk_tree, check that all elements with address taken are
3089 properly noticed as such. The DATA is an int* that is 1 if TP was seen
3090 inside a PHI node. */
3093 verify_expr (tree *tp, int *walk_subtrees, void *data ATTRIBUTE_UNUSED)
3096 bool in_phi = (data != NULL);
3101 /* Check operand N for being valid GIMPLE and give error MSG if not. */
3102 #define CHECK_OP(N, MSG) \
3103 do { if (!is_gimple_val (TREE_OPERAND (t, N))) \
3104 { error (MSG); return TREE_OPERAND (t, N); }} while (0)
3106 switch (TREE_CODE (t))
3109 if (SSA_NAME_IN_FREE_LIST (t))
3111 error ("SSA name in freelist but still referenced");
3117 x = fold (ASSERT_EXPR_COND (t));
3118 if (x == boolean_false_node)
3120 error ("ASSERT_EXPR with an always-false condition");
3126 x = TREE_OPERAND (t, 0);
3127 if (TREE_CODE (x) == BIT_FIELD_REF
3128 && is_gimple_reg (TREE_OPERAND (x, 0)))
3130 error ("GIMPLE register modified with BIT_FIELD_REF");
3139 bool old_side_effects;
3142 bool new_side_effects;
3144 /* ??? tree-ssa-alias.c may have overlooked dead PHI nodes, missing
3145 dead PHIs that take the address of something. But if the PHI
3146 result is dead, the fact that it takes the address of anything
3147 is irrelevant. Because we can not tell from here if a PHI result
3148 is dead, we just skip this check for PHIs altogether. This means
3149 we may be missing "valid" checks, but what can you do?
3150 This was PR19217. */
3154 old_invariant = TREE_INVARIANT (t);
3155 old_constant = TREE_CONSTANT (t);
3156 old_side_effects = TREE_SIDE_EFFECTS (t);
3158 recompute_tree_invarant_for_addr_expr (t);
3159 new_invariant = TREE_INVARIANT (t);
3160 new_side_effects = TREE_SIDE_EFFECTS (t);
3161 new_constant = TREE_CONSTANT (t);
3163 if (old_invariant != new_invariant)
3165 error ("invariant not recomputed when ADDR_EXPR changed");
3169 if (old_constant != new_constant)
3171 error ("constant not recomputed when ADDR_EXPR changed");
3174 if (old_side_effects != new_side_effects)
3176 error ("side effects not recomputed when ADDR_EXPR changed");
3180 /* Skip any references (they will be checked when we recurse down the
3181 tree) and ensure that any variable used as a prefix is marked
3183 for (x = TREE_OPERAND (t, 0);
3184 handled_component_p (x);
3185 x = TREE_OPERAND (x, 0))
3188 if (TREE_CODE (x) != VAR_DECL && TREE_CODE (x) != PARM_DECL)
3190 if (!TREE_ADDRESSABLE (x))
3192 error ("address taken, but ADDRESSABLE bit not set");
3199 x = COND_EXPR_COND (t);
3200 if (TREE_CODE (TREE_TYPE (x)) != BOOLEAN_TYPE)
3202 error ("non-boolean used in condition");
3205 if (!is_gimple_condexpr (x))
3207 error ("invalid conditional operand");
3214 case FIX_TRUNC_EXPR:
3216 case FIX_FLOOR_EXPR:
3217 case FIX_ROUND_EXPR:
3222 case NON_LVALUE_EXPR:
3223 case TRUTH_NOT_EXPR:
3224 CHECK_OP (0, "invalid operand to unary operator");
3231 case ARRAY_RANGE_REF:
3233 case VIEW_CONVERT_EXPR:
3234 /* We have a nest of references. Verify that each of the operands
3235 that determine where to reference is either a constant or a variable,
3236 verify that the base is valid, and then show we've already checked
3238 while (handled_component_p (t))
3240 if (TREE_CODE (t) == COMPONENT_REF && TREE_OPERAND (t, 2))
3241 CHECK_OP (2, "invalid COMPONENT_REF offset operator");
3242 else if (TREE_CODE (t) == ARRAY_REF
3243 || TREE_CODE (t) == ARRAY_RANGE_REF)
3245 CHECK_OP (1, "invalid array index");
3246 if (TREE_OPERAND (t, 2))
3247 CHECK_OP (2, "invalid array lower bound");
3248 if (TREE_OPERAND (t, 3))
3249 CHECK_OP (3, "invalid array stride");
3251 else if (TREE_CODE (t) == BIT_FIELD_REF)
3253 CHECK_OP (1, "invalid operand to BIT_FIELD_REF");
3254 CHECK_OP (2, "invalid operand to BIT_FIELD_REF");
3257 t = TREE_OPERAND (t, 0);
3260 if (!CONSTANT_CLASS_P (t) && !is_gimple_lvalue (t))
3262 error ("invalid reference prefix");
3274 case UNORDERED_EXPR:
3285 case TRUNC_DIV_EXPR:
3287 case FLOOR_DIV_EXPR:
3288 case ROUND_DIV_EXPR:
3289 case TRUNC_MOD_EXPR:
3291 case FLOOR_MOD_EXPR:
3292 case ROUND_MOD_EXPR:
3294 case EXACT_DIV_EXPR:
3304 CHECK_OP (0, "invalid operand to binary operator");
3305 CHECK_OP (1, "invalid operand to binary operator");
3317 /* Verify STMT, return true if STMT is not in GIMPLE form.
3318 TODO: Implement type checking. */
3321 verify_stmt (tree stmt, bool last_in_block)
3325 if (!is_gimple_stmt (stmt))
3327 error ("is not a valid GIMPLE statement");
3331 addr = walk_tree (&stmt, verify_expr, NULL, NULL);
3334 debug_generic_stmt (addr);
3338 /* If the statement is marked as part of an EH region, then it is
3339 expected that the statement could throw. Verify that when we
3340 have optimizations that simplify statements such that we prove
3341 that they cannot throw, that we update other data structures
3343 if (lookup_stmt_eh_region (stmt) >= 0)
3345 if (!tree_could_throw_p (stmt))
3347 error ("statement marked for throw, but doesn%'t");
3350 if (!last_in_block && tree_can_throw_internal (stmt))
3352 error ("statement marked for throw in middle of block");
3360 debug_generic_stmt (stmt);
3365 /* Return true when the T can be shared. */
3368 tree_node_can_be_shared (tree t)
3370 if (IS_TYPE_OR_DECL_P (t)
3371 /* We check for constants explicitly since they are not considered
3372 gimple invariants if they overflowed. */
3373 || CONSTANT_CLASS_P (t)
3374 || is_gimple_min_invariant (t)
3375 || TREE_CODE (t) == SSA_NAME
3376 || t == error_mark_node)
3379 if (TREE_CODE (t) == CASE_LABEL_EXPR)
3382 while (((TREE_CODE (t) == ARRAY_REF || TREE_CODE (t) == ARRAY_RANGE_REF)
3383 /* We check for constants explicitly since they are not considered
3384 gimple invariants if they overflowed. */
3385 && (CONSTANT_CLASS_P (TREE_OPERAND (t, 1))
3386 || is_gimple_min_invariant (TREE_OPERAND (t, 1))))
3387 || (TREE_CODE (t) == COMPONENT_REF
3388 || TREE_CODE (t) == REALPART_EXPR
3389 || TREE_CODE (t) == IMAGPART_EXPR))
3390 t = TREE_OPERAND (t, 0);
3399 /* Called via walk_trees. Verify tree sharing. */
3402 verify_node_sharing (tree * tp, int *walk_subtrees, void *data)
3404 htab_t htab = (htab_t) data;
3407 if (tree_node_can_be_shared (*tp))
3409 *walk_subtrees = false;
3413 slot = htab_find_slot (htab, *tp, INSERT);
3422 /* Verify the GIMPLE statement chain. */
3428 block_stmt_iterator bsi;
3433 timevar_push (TV_TREE_STMT_VERIFY);
3434 htab = htab_create (37, htab_hash_pointer, htab_eq_pointer, NULL);
3441 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
3443 int phi_num_args = PHI_NUM_ARGS (phi);
3445 if (bb_for_stmt (phi) != bb)
3447 error ("bb_for_stmt (phi) is set to a wrong basic block");
3451 for (i = 0; i < phi_num_args; i++)
3453 tree t = PHI_ARG_DEF (phi, i);
3456 /* Addressable variables do have SSA_NAMEs but they
3457 are not considered gimple values. */
3458 if (TREE_CODE (t) != SSA_NAME
3459 && TREE_CODE (t) != FUNCTION_DECL
3460 && !is_gimple_val (t))
3462 error ("PHI def is not a GIMPLE value");
3463 debug_generic_stmt (phi);
3464 debug_generic_stmt (t);
3468 addr = walk_tree (&t, verify_expr, (void *) 1, NULL);
3471 debug_generic_stmt (addr);
3475 addr = walk_tree (&t, verify_node_sharing, htab, NULL);
3478 error ("incorrect sharing of tree nodes");
3479 debug_generic_stmt (phi);
3480 debug_generic_stmt (addr);
3486 for (bsi = bsi_start (bb); !bsi_end_p (bsi); )
3488 tree stmt = bsi_stmt (bsi);
3490 if (bb_for_stmt (stmt) != bb)
3492 error ("bb_for_stmt (stmt) is set to a wrong basic block");
3497 err |= verify_stmt (stmt, bsi_end_p (bsi));
3498 addr = walk_tree (&stmt, verify_node_sharing, htab, NULL);
3501 error ("incorrect sharing of tree nodes");
3502 debug_generic_stmt (stmt);
3503 debug_generic_stmt (addr);
3510 internal_error ("verify_stmts failed");
3513 timevar_pop (TV_TREE_STMT_VERIFY);
3517 /* Verifies that the flow information is OK. */
3520 tree_verify_flow_info (void)
3524 block_stmt_iterator bsi;
3529 if (ENTRY_BLOCK_PTR->stmt_list)
3531 error ("ENTRY_BLOCK has a statement list associated with it");
3535 if (EXIT_BLOCK_PTR->stmt_list)
3537 error ("EXIT_BLOCK has a statement list associated with it");
3541 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
3542 if (e->flags & EDGE_FALLTHRU)
3544 error ("fallthru to exit from bb %d", e->src->index);
3550 bool found_ctrl_stmt = false;
3554 /* Skip labels on the start of basic block. */
3555 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3557 tree prev_stmt = stmt;
3559 stmt = bsi_stmt (bsi);
3561 if (TREE_CODE (stmt) != LABEL_EXPR)
3564 if (prev_stmt && DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)))
3566 error ("nonlocal label %s is not first "
3567 "in a sequence of labels in bb %d",
3568 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt))),
3573 if (label_to_block (LABEL_EXPR_LABEL (stmt)) != bb)
3575 error ("label %s to block does not match in bb %d",
3576 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt))),
3581 if (decl_function_context (LABEL_EXPR_LABEL (stmt))
3582 != current_function_decl)
3584 error ("label %s has incorrect context in bb %d",
3585 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt))),
3591 /* Verify that body of basic block BB is free of control flow. */
3592 for (; !bsi_end_p (bsi); bsi_next (&bsi))
3594 tree stmt = bsi_stmt (bsi);
3596 if (found_ctrl_stmt)
3598 error ("control flow in the middle of basic block %d",
3603 if (stmt_ends_bb_p (stmt))
3604 found_ctrl_stmt = true;
3606 if (TREE_CODE (stmt) == LABEL_EXPR)
3608 error ("label %s in the middle of basic block %d",
3609 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt))),
3614 bsi = bsi_last (bb);
3615 if (bsi_end_p (bsi))
3618 stmt = bsi_stmt (bsi);
3620 err |= verify_eh_edges (stmt);
3622 if (is_ctrl_stmt (stmt))
3624 FOR_EACH_EDGE (e, ei, bb->succs)
3625 if (e->flags & EDGE_FALLTHRU)
3627 error ("fallthru edge after a control statement in bb %d",
3633 switch (TREE_CODE (stmt))
3639 if (TREE_CODE (COND_EXPR_THEN (stmt)) != GOTO_EXPR
3640 || TREE_CODE (COND_EXPR_ELSE (stmt)) != GOTO_EXPR)
3642 error ("structured COND_EXPR at the end of bb %d", bb->index);
3646 extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
3648 if (!true_edge || !false_edge
3649 || !(true_edge->flags & EDGE_TRUE_VALUE)
3650 || !(false_edge->flags & EDGE_FALSE_VALUE)
3651 || (true_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL))
3652 || (false_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL))
3653 || EDGE_COUNT (bb->succs) >= 3)
3655 error ("wrong outgoing edge flags at end of bb %d",
3660 if (!has_label_p (true_edge->dest,
3661 GOTO_DESTINATION (COND_EXPR_THEN (stmt))))
3663 error ("%<then%> label does not match edge at end of bb %d",
3668 if (!has_label_p (false_edge->dest,
3669 GOTO_DESTINATION (COND_EXPR_ELSE (stmt))))
3671 error ("%<else%> label does not match edge at end of bb %d",
3679 if (simple_goto_p (stmt))
3681 error ("explicit goto at end of bb %d", bb->index);
3686 /* FIXME. We should double check that the labels in the
3687 destination blocks have their address taken. */
3688 FOR_EACH_EDGE (e, ei, bb->succs)
3689 if ((e->flags & (EDGE_FALLTHRU | EDGE_TRUE_VALUE
3690 | EDGE_FALSE_VALUE))
3691 || !(e->flags & EDGE_ABNORMAL))
3693 error ("wrong outgoing edge flags at end of bb %d",
3701 if (!single_succ_p (bb)
3702 || (single_succ_edge (bb)->flags
3703 & (EDGE_FALLTHRU | EDGE_ABNORMAL
3704 | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
3706 error ("wrong outgoing edge flags at end of bb %d", bb->index);
3709 if (single_succ (bb) != EXIT_BLOCK_PTR)
3711 error ("return edge does not point to exit in bb %d",
3724 vec = SWITCH_LABELS (stmt);
3725 n = TREE_VEC_LENGTH (vec);
3727 /* Mark all the destination basic blocks. */
3728 for (i = 0; i < n; ++i)
3730 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
3731 basic_block label_bb = label_to_block (lab);
3733 gcc_assert (!label_bb->aux || label_bb->aux == (void *)1);
3734 label_bb->aux = (void *)1;
3737 /* Verify that the case labels are sorted. */
3738 prev = TREE_VEC_ELT (vec, 0);
3739 for (i = 1; i < n - 1; ++i)
3741 tree c = TREE_VEC_ELT (vec, i);
3744 error ("found default case not at end of case vector");
3748 if (! tree_int_cst_lt (CASE_LOW (prev), CASE_LOW (c)))
3750 error ("case labels not sorted:");
3751 print_generic_expr (stderr, prev, 0);
3752 fprintf (stderr," is greater than ");
3753 print_generic_expr (stderr, c, 0);
3754 fprintf (stderr," but comes before it.\n");
3759 if (CASE_LOW (TREE_VEC_ELT (vec, n - 1)))
3761 error ("no default case found at end of case vector");
3765 FOR_EACH_EDGE (e, ei, bb->succs)
3769 error ("extra outgoing edge %d->%d",
3770 bb->index, e->dest->index);
3773 e->dest->aux = (void *)2;
3774 if ((e->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL
3775 | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
3777 error ("wrong outgoing edge flags at end of bb %d",
3783 /* Check that we have all of them. */
3784 for (i = 0; i < n; ++i)
3786 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
3787 basic_block label_bb = label_to_block (lab);
3789 if (label_bb->aux != (void *)2)
3791 error ("missing edge %i->%i",
3792 bb->index, label_bb->index);
3797 FOR_EACH_EDGE (e, ei, bb->succs)
3798 e->dest->aux = (void *)0;
3805 if (dom_computed[CDI_DOMINATORS] >= DOM_NO_FAST_QUERY)
3806 verify_dominators (CDI_DOMINATORS);
3812 /* Updates phi nodes after creating a forwarder block joined
3813 by edge FALLTHRU. */
3816 tree_make_forwarder_block (edge fallthru)
3820 basic_block dummy, bb;
3821 tree phi, new_phi, var;
3823 dummy = fallthru->src;
3824 bb = fallthru->dest;
3826 if (single_pred_p (bb))
3829 /* If we redirected a branch we must create new phi nodes at the
3831 for (phi = phi_nodes (dummy); phi; phi = PHI_CHAIN (phi))
3833 var = PHI_RESULT (phi);
3834 new_phi = create_phi_node (var, bb);
3835 SSA_NAME_DEF_STMT (var) = new_phi;
3836 SET_PHI_RESULT (phi, make_ssa_name (SSA_NAME_VAR (var), phi));
3837 add_phi_arg (new_phi, PHI_RESULT (phi), fallthru);
3840 /* Ensure that the PHI node chain is in the same order. */
3841 set_phi_nodes (bb, phi_reverse (phi_nodes (bb)));
3843 /* Add the arguments we have stored on edges. */
3844 FOR_EACH_EDGE (e, ei, bb->preds)
3849 flush_pending_stmts (e);
3854 /* Return a non-special label in the head of basic block BLOCK.
3855 Create one if it doesn't exist. */
3858 tree_block_label (basic_block bb)
3860 block_stmt_iterator i, s = bsi_start (bb);
3864 for (i = s; !bsi_end_p (i); first = false, bsi_next (&i))
3866 stmt = bsi_stmt (i);
3867 if (TREE_CODE (stmt) != LABEL_EXPR)
3869 label = LABEL_EXPR_LABEL (stmt);
3870 if (!DECL_NONLOCAL (label))
3873 bsi_move_before (&i, &s);
3878 label = create_artificial_label ();
3879 stmt = build1 (LABEL_EXPR, void_type_node, label);
3880 bsi_insert_before (&s, stmt, BSI_NEW_STMT);
3885 /* Attempt to perform edge redirection by replacing a possibly complex
3886 jump instruction by a goto or by removing the jump completely.
3887 This can apply only if all edges now point to the same block. The
3888 parameters and return values are equivalent to
3889 redirect_edge_and_branch. */
3892 tree_try_redirect_by_replacing_jump (edge e, basic_block target)
3894 basic_block src = e->src;
3895 block_stmt_iterator b;
3898 /* We can replace or remove a complex jump only when we have exactly
3900 if (EDGE_COUNT (src->succs) != 2
3901 /* Verify that all targets will be TARGET. Specifically, the
3902 edge that is not E must also go to TARGET. */
3903 || EDGE_SUCC (src, EDGE_SUCC (src, 0) == e)->dest != target)
3909 stmt = bsi_stmt (b);
3911 if (TREE_CODE (stmt) == COND_EXPR
3912 || TREE_CODE (stmt) == SWITCH_EXPR)
3915 e = ssa_redirect_edge (e, target);
3916 e->flags = EDGE_FALLTHRU;
3924 /* Redirect E to DEST. Return NULL on failure. Otherwise, return the
3925 edge representing the redirected branch. */
3928 tree_redirect_edge_and_branch (edge e, basic_block dest)
3930 basic_block bb = e->src;
3931 block_stmt_iterator bsi;
3935 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
3938 if (e->src != ENTRY_BLOCK_PTR
3939 && (ret = tree_try_redirect_by_replacing_jump (e, dest)))
3942 if (e->dest == dest)
3945 label = tree_block_label (dest);
3947 bsi = bsi_last (bb);
3948 stmt = bsi_end_p (bsi) ? NULL : bsi_stmt (bsi);
3950 switch (stmt ? TREE_CODE (stmt) : ERROR_MARK)
3953 stmt = (e->flags & EDGE_TRUE_VALUE
3954 ? COND_EXPR_THEN (stmt)
3955 : COND_EXPR_ELSE (stmt));
3956 GOTO_DESTINATION (stmt) = label;
3960 /* No non-abnormal edges should lead from a non-simple goto, and
3961 simple ones should be represented implicitly. */
3966 tree cases = get_cases_for_edge (e, stmt);
3968 /* If we have a list of cases associated with E, then use it
3969 as it's a lot faster than walking the entire case vector. */
3972 edge e2 = find_edge (e->src, dest);
3979 CASE_LABEL (cases) = label;
3980 cases = TREE_CHAIN (cases);
3983 /* If there was already an edge in the CFG, then we need
3984 to move all the cases associated with E to E2. */
3987 tree cases2 = get_cases_for_edge (e2, stmt);
3989 TREE_CHAIN (last) = TREE_CHAIN (cases2);
3990 TREE_CHAIN (cases2) = first;
3995 tree vec = SWITCH_LABELS (stmt);
3996 size_t i, n = TREE_VEC_LENGTH (vec);
3998 for (i = 0; i < n; i++)
4000 tree elt = TREE_VEC_ELT (vec, i);
4002 if (label_to_block (CASE_LABEL (elt)) == e->dest)
4003 CASE_LABEL (elt) = label;
4012 e->flags |= EDGE_FALLTHRU;
4016 /* Otherwise it must be a fallthru edge, and we don't need to
4017 do anything besides redirecting it. */
4018 gcc_assert (e->flags & EDGE_FALLTHRU);
4022 /* Update/insert PHI nodes as necessary. */
4024 /* Now update the edges in the CFG. */
4025 e = ssa_redirect_edge (e, dest);
4031 /* Simple wrapper, as we can always redirect fallthru edges. */
4034 tree_redirect_edge_and_branch_force (edge e, basic_block dest)
4036 e = tree_redirect_edge_and_branch (e, dest);
4043 /* Splits basic block BB after statement STMT (but at least after the
4044 labels). If STMT is NULL, BB is split just after the labels. */
4047 tree_split_block (basic_block bb, void *stmt)
4049 block_stmt_iterator bsi, bsi_tgt;
4055 new_bb = create_empty_bb (bb);
4057 /* Redirect the outgoing edges. */
4058 new_bb->succs = bb->succs;
4060 FOR_EACH_EDGE (e, ei, new_bb->succs)
4063 if (stmt && TREE_CODE ((tree) stmt) == LABEL_EXPR)
4066 /* Move everything from BSI to the new basic block. */
4067 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4069 act = bsi_stmt (bsi);
4070 if (TREE_CODE (act) == LABEL_EXPR)
4083 bsi_tgt = bsi_start (new_bb);
4084 while (!bsi_end_p (bsi))
4086 act = bsi_stmt (bsi);
4088 bsi_insert_after (&bsi_tgt, act, BSI_NEW_STMT);
4095 /* Moves basic block BB after block AFTER. */
4098 tree_move_block_after (basic_block bb, basic_block after)
4100 if (bb->prev_bb == after)
4104 link_block (bb, after);
4110 /* Return true if basic_block can be duplicated. */
4113 tree_can_duplicate_bb_p (basic_block bb ATTRIBUTE_UNUSED)
4119 /* Create a duplicate of the basic block BB. NOTE: This does not
4120 preserve SSA form. */
4123 tree_duplicate_bb (basic_block bb)
4126 block_stmt_iterator bsi, bsi_tgt;
4129 new_bb = create_empty_bb (EXIT_BLOCK_PTR->prev_bb);
4131 /* Copy the PHI nodes. We ignore PHI node arguments here because
4132 the incoming edges have not been setup yet. */
4133 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
4135 tree copy = create_phi_node (PHI_RESULT (phi), new_bb);
4136 create_new_def_for (PHI_RESULT (copy), copy, PHI_RESULT_PTR (copy));
4139 /* Keep the chain of PHI nodes in the same order so that they can be
4140 updated by ssa_redirect_edge. */
4141 set_phi_nodes (new_bb, phi_reverse (phi_nodes (new_bb)));
4143 bsi_tgt = bsi_start (new_bb);
4144 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4146 def_operand_p def_p;
4147 ssa_op_iter op_iter;
4151 stmt = bsi_stmt (bsi);
4152 if (TREE_CODE (stmt) == LABEL_EXPR)
4155 /* Create a new copy of STMT and duplicate STMT's virtual
4157 copy = unshare_expr (stmt);
4158 bsi_insert_after (&bsi_tgt, copy, BSI_NEW_STMT);
4159 copy_virtual_operands (copy, stmt);
4160 region = lookup_stmt_eh_region (stmt);
4162 add_stmt_to_eh_region (copy, region);
4164 /* Create new names for all the definitions created by COPY and
4165 add replacement mappings for each new name. */
4166 FOR_EACH_SSA_DEF_OPERAND (def_p, copy, op_iter, SSA_OP_ALL_DEFS)
4167 create_new_def_for (DEF_FROM_PTR (def_p), copy, def_p);
4174 /* Basic block BB_COPY was created by code duplication. Add phi node
4175 arguments for edges going out of BB_COPY. The blocks that were
4176 duplicated have BB_DUPLICATED set. */
4179 add_phi_args_after_copy_bb (basic_block bb_copy)
4181 basic_block bb, dest;
4184 tree phi, phi_copy, phi_next, def;
4186 bb = get_bb_original (bb_copy);
4188 FOR_EACH_EDGE (e_copy, ei, bb_copy->succs)
4190 if (!phi_nodes (e_copy->dest))
4193 if (e_copy->dest->flags & BB_DUPLICATED)
4194 dest = get_bb_original (e_copy->dest);
4196 dest = e_copy->dest;
4198 e = find_edge (bb, dest);
4201 /* During loop unrolling the target of the latch edge is copied.
4202 In this case we are not looking for edge to dest, but to
4203 duplicated block whose original was dest. */
4204 FOR_EACH_EDGE (e, ei, bb->succs)
4205 if ((e->dest->flags & BB_DUPLICATED)
4206 && get_bb_original (e->dest) == dest)
4209 gcc_assert (e != NULL);
4212 for (phi = phi_nodes (e->dest), phi_copy = phi_nodes (e_copy->dest);
4214 phi = phi_next, phi_copy = PHI_CHAIN (phi_copy))
4216 phi_next = PHI_CHAIN (phi);
4217 def = PHI_ARG_DEF_FROM_EDGE (phi, e);
4218 add_phi_arg (phi_copy, def, e_copy);
4223 /* Blocks in REGION_COPY array of length N_REGION were created by
4224 duplication of basic blocks. Add phi node arguments for edges
4225 going from these blocks. */
4228 add_phi_args_after_copy (basic_block *region_copy, unsigned n_region)
4232 for (i = 0; i < n_region; i++)
4233 region_copy[i]->flags |= BB_DUPLICATED;
4235 for (i = 0; i < n_region; i++)
4236 add_phi_args_after_copy_bb (region_copy[i]);
4238 for (i = 0; i < n_region; i++)
4239 region_copy[i]->flags &= ~BB_DUPLICATED;
4242 /* Duplicates a REGION (set of N_REGION basic blocks) with just a single
4243 important exit edge EXIT. By important we mean that no SSA name defined
4244 inside region is live over the other exit edges of the region. All entry
4245 edges to the region must go to ENTRY->dest. The edge ENTRY is redirected
4246 to the duplicate of the region. SSA form, dominance and loop information
4247 is updated. The new basic blocks are stored to REGION_COPY in the same
4248 order as they had in REGION, provided that REGION_COPY is not NULL.
4249 The function returns false if it is unable to copy the region,
4253 tree_duplicate_sese_region (edge entry, edge exit,
4254 basic_block *region, unsigned n_region,
4255 basic_block *region_copy)
4258 bool free_region_copy = false, copying_header = false;
4259 struct loop *loop = entry->dest->loop_father;
4263 int total_freq = 0, entry_freq = 0;
4264 gcov_type total_count = 0, entry_count = 0;
4266 if (!can_copy_bbs_p (region, n_region))
4269 /* Some sanity checking. Note that we do not check for all possible
4270 missuses of the functions. I.e. if you ask to copy something weird,
4271 it will work, but the state of structures probably will not be
4273 for (i = 0; i < n_region; i++)
4275 /* We do not handle subloops, i.e. all the blocks must belong to the
4277 if (region[i]->loop_father != loop)
4280 if (region[i] != entry->dest
4281 && region[i] == loop->header)
4287 /* In case the function is used for loop header copying (which is the primary
4288 use), ensure that EXIT and its copy will be new latch and entry edges. */
4289 if (loop->header == entry->dest)
4291 copying_header = true;
4292 loop->copy = loop->outer;
4294 if (!dominated_by_p (CDI_DOMINATORS, loop->latch, exit->src))
4297 for (i = 0; i < n_region; i++)
4298 if (region[i] != exit->src
4299 && dominated_by_p (CDI_DOMINATORS, region[i], exit->src))
4305 region_copy = xmalloc (sizeof (basic_block) * n_region);
4306 free_region_copy = true;
4309 gcc_assert (!need_ssa_update_p ());
4311 /* Record blocks outside the region that are dominated by something
4313 doms = xmalloc (sizeof (basic_block) * n_basic_blocks);
4314 initialize_original_copy_tables ();
4316 n_doms = get_dominated_by_region (CDI_DOMINATORS, region, n_region, doms);
4318 if (entry->dest->count)
4320 total_count = entry->dest->count;
4321 entry_count = entry->count;
4322 /* Fix up corner cases, to avoid division by zero or creation of negative
4324 if (entry_count > total_count)
4325 entry_count = total_count;
4329 total_freq = entry->dest->frequency;
4330 entry_freq = EDGE_FREQUENCY (entry);
4331 /* Fix up corner cases, to avoid division by zero or creation of negative
4333 if (total_freq == 0)
4335 else if (entry_freq > total_freq)
4336 entry_freq = total_freq;
4339 copy_bbs (region, n_region, region_copy, &exit, 1, &exit_copy, loop);
4342 scale_bbs_frequencies_gcov_type (region, n_region,
4343 total_count - entry_count,
4345 scale_bbs_frequencies_gcov_type (region_copy, n_region, entry_count,
4350 scale_bbs_frequencies_int (region, n_region, total_freq - entry_freq,
4352 scale_bbs_frequencies_int (region_copy, n_region, entry_freq, total_freq);
4357 loop->header = exit->dest;
4358 loop->latch = exit->src;
4361 /* Redirect the entry and add the phi node arguments. */
4362 redirected = redirect_edge_and_branch (entry, get_bb_copy (entry->dest));
4363 gcc_assert (redirected != NULL);
4364 flush_pending_stmts (entry);
4366 /* Concerning updating of dominators: We must recount dominators
4367 for entry block and its copy. Anything that is outside of the
4368 region, but was dominated by something inside needs recounting as
4370 set_immediate_dominator (CDI_DOMINATORS, entry->dest, entry->src);
4371 doms[n_doms++] = get_bb_original (entry->dest);
4372 iterate_fix_dominators (CDI_DOMINATORS, doms, n_doms);
4375 /* Add the other PHI node arguments. */
4376 add_phi_args_after_copy (region_copy, n_region);
4378 /* Update the SSA web. */
4379 update_ssa (TODO_update_ssa);
4381 if (free_region_copy)
4384 free_original_copy_tables ();
4389 /* Dump FUNCTION_DECL FN to file FILE using FLAGS (see TDF_* in tree.h) */
4392 dump_function_to_file (tree fn, FILE *file, int flags)
4394 tree arg, vars, var;
4395 bool ignore_topmost_bind = false, any_var = false;
4399 fprintf (file, "%s (", lang_hooks.decl_printable_name (fn, 2));
4401 arg = DECL_ARGUMENTS (fn);
4404 print_generic_expr (file, arg, dump_flags);
4405 if (TREE_CHAIN (arg))
4406 fprintf (file, ", ");
4407 arg = TREE_CHAIN (arg);
4409 fprintf (file, ")\n");
4411 if (flags & TDF_DETAILS)
4412 dump_eh_tree (file, DECL_STRUCT_FUNCTION (fn));
4413 if (flags & TDF_RAW)
4415 dump_node (fn, TDF_SLIM | flags, file);
4419 /* When GIMPLE is lowered, the variables are no longer available in
4420 BIND_EXPRs, so display them separately. */
4421 if (cfun && cfun->decl == fn && cfun->unexpanded_var_list)
4423 ignore_topmost_bind = true;
4425 fprintf (file, "{\n");
4426 for (vars = cfun->unexpanded_var_list; vars; vars = TREE_CHAIN (vars))
4428 var = TREE_VALUE (vars);
4430 print_generic_decl (file, var, flags);
4431 fprintf (file, "\n");
4437 if (cfun && cfun->decl == fn && cfun->cfg && basic_block_info)
4439 /* Make a CFG based dump. */
4440 check_bb_profile (ENTRY_BLOCK_PTR, file);
4441 if (!ignore_topmost_bind)
4442 fprintf (file, "{\n");
4444 if (any_var && n_basic_blocks)
4445 fprintf (file, "\n");
4448 dump_generic_bb (file, bb, 2, flags);
4450 fprintf (file, "}\n");
4451 check_bb_profile (EXIT_BLOCK_PTR, file);
4457 /* Make a tree based dump. */
4458 chain = DECL_SAVED_TREE (fn);
4460 if (TREE_CODE (chain) == BIND_EXPR)
4462 if (ignore_topmost_bind)
4464 chain = BIND_EXPR_BODY (chain);
4472 if (!ignore_topmost_bind)
4473 fprintf (file, "{\n");
4478 fprintf (file, "\n");
4480 print_generic_stmt_indented (file, chain, flags, indent);
4481 if (ignore_topmost_bind)
4482 fprintf (file, "}\n");
4485 fprintf (file, "\n\n");
4489 /* Pretty print of the loops intermediate representation. */
4490 static void print_loop (FILE *, struct loop *, int);
4491 static void print_pred_bbs (FILE *, basic_block bb);
4492 static void print_succ_bbs (FILE *, basic_block bb);
4495 /* Print the predecessors indexes of edge E on FILE. */
4498 print_pred_bbs (FILE *file, basic_block bb)
4503 FOR_EACH_EDGE (e, ei, bb->preds)
4504 fprintf (file, "bb_%d", e->src->index);
4508 /* Print the successors indexes of edge E on FILE. */
4511 print_succ_bbs (FILE *file, basic_block bb)
4516 FOR_EACH_EDGE (e, ei, bb->succs)
4517 fprintf (file, "bb_%d", e->src->index);
4521 /* Pretty print LOOP on FILE, indented INDENT spaces. */
4524 print_loop (FILE *file, struct loop *loop, int indent)
4532 s_indent = (char *) alloca ((size_t) indent + 1);
4533 memset ((void *) s_indent, ' ', (size_t) indent);
4534 s_indent[indent] = '\0';
4536 /* Print the loop's header. */
4537 fprintf (file, "%sloop_%d\n", s_indent, loop->num);
4539 /* Print the loop's body. */
4540 fprintf (file, "%s{\n", s_indent);
4542 if (bb->loop_father == loop)
4544 /* Print the basic_block's header. */
4545 fprintf (file, "%s bb_%d (preds = {", s_indent, bb->index);
4546 print_pred_bbs (file, bb);
4547 fprintf (file, "}, succs = {");
4548 print_succ_bbs (file, bb);
4549 fprintf (file, "})\n");
4551 /* Print the basic_block's body. */
4552 fprintf (file, "%s {\n", s_indent);
4553 tree_dump_bb (bb, file, indent + 4);
4554 fprintf (file, "%s }\n", s_indent);
4557 print_loop (file, loop->inner, indent + 2);
4558 fprintf (file, "%s}\n", s_indent);
4559 print_loop (file, loop->next, indent);
4563 /* Follow a CFG edge from the entry point of the program, and on entry
4564 of a loop, pretty print the loop structure on FILE. */
4567 print_loop_ir (FILE *file)
4571 bb = BASIC_BLOCK (0);
4572 if (bb && bb->loop_father)
4573 print_loop (file, bb->loop_father, 0);
4577 /* Debugging loops structure at tree level. */
4580 debug_loop_ir (void)
4582 print_loop_ir (stderr);
4586 /* Return true if BB ends with a call, possibly followed by some
4587 instructions that must stay with the call. Return false,
4591 tree_block_ends_with_call_p (basic_block bb)
4593 block_stmt_iterator bsi = bsi_last (bb);
4594 return get_call_expr_in (bsi_stmt (bsi)) != NULL;
4598 /* Return true if BB ends with a conditional branch. Return false,
4602 tree_block_ends_with_condjump_p (basic_block bb)
4604 tree stmt = last_stmt (bb);
4605 return (stmt && TREE_CODE (stmt) == COND_EXPR);
4609 /* Return true if we need to add fake edge to exit at statement T.
4610 Helper function for tree_flow_call_edges_add. */
4613 need_fake_edge_p (tree t)
4617 /* NORETURN and LONGJMP calls already have an edge to exit.
4618 CONST and PURE calls do not need one.
4619 We don't currently check for CONST and PURE here, although
4620 it would be a good idea, because those attributes are
4621 figured out from the RTL in mark_constant_function, and
4622 the counter incrementation code from -fprofile-arcs
4623 leads to different results from -fbranch-probabilities. */
4624 call = get_call_expr_in (t);
4626 && !(call_expr_flags (call) & ECF_NORETURN))
4629 if (TREE_CODE (t) == ASM_EXPR
4630 && (ASM_VOLATILE_P (t) || ASM_INPUT_P (t)))
4637 /* Add fake edges to the function exit for any non constant and non
4638 noreturn calls, volatile inline assembly in the bitmap of blocks
4639 specified by BLOCKS or to the whole CFG if BLOCKS is zero. Return
4640 the number of blocks that were split.
4642 The goal is to expose cases in which entering a basic block does
4643 not imply that all subsequent instructions must be executed. */
4646 tree_flow_call_edges_add (sbitmap blocks)
4649 int blocks_split = 0;
4650 int last_bb = last_basic_block;
4651 bool check_last_block = false;
4653 if (n_basic_blocks == 0)
4657 check_last_block = true;
4659 check_last_block = TEST_BIT (blocks, EXIT_BLOCK_PTR->prev_bb->index);
4661 /* In the last basic block, before epilogue generation, there will be
4662 a fallthru edge to EXIT. Special care is required if the last insn
4663 of the last basic block is a call because make_edge folds duplicate
4664 edges, which would result in the fallthru edge also being marked
4665 fake, which would result in the fallthru edge being removed by
4666 remove_fake_edges, which would result in an invalid CFG.
4668 Moreover, we can't elide the outgoing fake edge, since the block
4669 profiler needs to take this into account in order to solve the minimal
4670 spanning tree in the case that the call doesn't return.
4672 Handle this by adding a dummy instruction in a new last basic block. */
4673 if (check_last_block)
4675 basic_block bb = EXIT_BLOCK_PTR->prev_bb;
4676 block_stmt_iterator bsi = bsi_last (bb);
4678 if (!bsi_end_p (bsi))
4681 if (need_fake_edge_p (t))
4685 e = find_edge (bb, EXIT_BLOCK_PTR);
4688 bsi_insert_on_edge (e, build_empty_stmt ());
4689 bsi_commit_edge_inserts ();
4694 /* Now add fake edges to the function exit for any non constant
4695 calls since there is no way that we can determine if they will
4697 for (i = 0; i < last_bb; i++)
4699 basic_block bb = BASIC_BLOCK (i);
4700 block_stmt_iterator bsi;
4701 tree stmt, last_stmt;
4706 if (blocks && !TEST_BIT (blocks, i))
4709 bsi = bsi_last (bb);
4710 if (!bsi_end_p (bsi))
4712 last_stmt = bsi_stmt (bsi);
4715 stmt = bsi_stmt (bsi);
4716 if (need_fake_edge_p (stmt))
4719 /* The handling above of the final block before the
4720 epilogue should be enough to verify that there is
4721 no edge to the exit block in CFG already.
4722 Calling make_edge in such case would cause us to
4723 mark that edge as fake and remove it later. */
4724 #ifdef ENABLE_CHECKING
4725 if (stmt == last_stmt)
4727 e = find_edge (bb, EXIT_BLOCK_PTR);
4728 gcc_assert (e == NULL);
4732 /* Note that the following may create a new basic block
4733 and renumber the existing basic blocks. */
4734 if (stmt != last_stmt)
4736 e = split_block (bb, stmt);
4740 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
4744 while (!bsi_end_p (bsi));
4749 verify_flow_info ();
4751 return blocks_split;
4755 tree_purge_dead_eh_edges (basic_block bb)
4757 bool changed = false;
4760 tree stmt = last_stmt (bb);
4762 if (stmt && tree_can_throw_internal (stmt))
4765 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
4767 if (e->flags & EDGE_EH)
4776 /* Removal of dead EH edges might change dominators of not
4777 just immediate successors. E.g. when bb1 is changed so that
4778 it no longer can throw and bb1->bb3 and bb1->bb4 are dead
4779 eh edges purged by this function in:
4791 idom(bb5) must be recomputed. For now just free the dominance
4794 free_dominance_info (CDI_DOMINATORS);
4800 tree_purge_all_dead_eh_edges (bitmap blocks)
4802 bool changed = false;
4806 EXECUTE_IF_SET_IN_BITMAP (blocks, 0, i, bi)
4808 changed |= tree_purge_dead_eh_edges (BASIC_BLOCK (i));
4814 /* This function is called whenever a new edge is created or
4818 tree_execute_on_growing_pred (edge e)
4820 basic_block bb = e->dest;
4823 reserve_phi_args_for_new_edge (bb);
4826 /* This function is called immediately before edge E is removed from
4827 the edge vector E->dest->preds. */
4830 tree_execute_on_shrinking_pred (edge e)
4832 if (phi_nodes (e->dest))
4833 remove_phi_args (e);
4836 /*---------------------------------------------------------------------------
4837 Helper functions for Loop versioning
4838 ---------------------------------------------------------------------------*/
4840 /* Adjust phi nodes for 'first' basic block. 'second' basic block is a copy
4841 of 'first'. Both of them are dominated by 'new_head' basic block. When
4842 'new_head' was created by 'second's incoming edge it received phi arguments
4843 on the edge by split_edge(). Later, additional edge 'e' was created to
4844 connect 'new_head' and 'first'. Now this routine adds phi args on this
4845 additional edge 'e' that new_head to second edge received as part of edge
4850 tree_lv_adjust_loop_header_phi (basic_block first, basic_block second,
4851 basic_block new_head, edge e)
4854 edge e2 = find_edge (new_head, second);
4856 /* Because NEW_HEAD has been created by splitting SECOND's incoming
4857 edge, we should always have an edge from NEW_HEAD to SECOND. */
4858 gcc_assert (e2 != NULL);
4860 /* Browse all 'second' basic block phi nodes and add phi args to
4861 edge 'e' for 'first' head. PHI args are always in correct order. */
4863 for (phi2 = phi_nodes (second), phi1 = phi_nodes (first);
4865 phi2 = PHI_CHAIN (phi2), phi1 = PHI_CHAIN (phi1))
4867 tree def = PHI_ARG_DEF (phi2, e2->dest_idx);
4868 add_phi_arg (phi1, def, e);
4872 /* Adds a if else statement to COND_BB with condition COND_EXPR.
4873 SECOND_HEAD is the destination of the THEN and FIRST_HEAD is
4874 the destination of the ELSE part. */
4876 tree_lv_add_condition_to_bb (basic_block first_head, basic_block second_head,
4877 basic_block cond_bb, void *cond_e)
4879 block_stmt_iterator bsi;
4880 tree goto1 = NULL_TREE;
4881 tree goto2 = NULL_TREE;
4882 tree new_cond_expr = NULL_TREE;
4883 tree cond_expr = (tree) cond_e;
4886 /* Build new conditional expr */
4887 goto1 = build1 (GOTO_EXPR, void_type_node, tree_block_label (first_head));
4888 goto2 = build1 (GOTO_EXPR, void_type_node, tree_block_label (second_head));
4889 new_cond_expr = build3 (COND_EXPR, void_type_node, cond_expr, goto1, goto2);
4891 /* Add new cond in cond_bb. */
4892 bsi = bsi_start (cond_bb);
4893 bsi_insert_after (&bsi, new_cond_expr, BSI_NEW_STMT);
4894 /* Adjust edges appropriately to connect new head with first head
4895 as well as second head. */
4896 e0 = single_succ_edge (cond_bb);
4897 e0->flags &= ~EDGE_FALLTHRU;
4898 e0->flags |= EDGE_FALSE_VALUE;
4901 struct cfg_hooks tree_cfg_hooks = {
4903 tree_verify_flow_info,
4904 tree_dump_bb, /* dump_bb */
4905 create_bb, /* create_basic_block */
4906 tree_redirect_edge_and_branch,/* redirect_edge_and_branch */
4907 tree_redirect_edge_and_branch_force,/* redirect_edge_and_branch_force */
4908 remove_bb, /* delete_basic_block */
4909 tree_split_block, /* split_block */
4910 tree_move_block_after, /* move_block_after */
4911 tree_can_merge_blocks_p, /* can_merge_blocks_p */
4912 tree_merge_blocks, /* merge_blocks */
4913 tree_predict_edge, /* predict_edge */
4914 tree_predicted_by_p, /* predicted_by_p */
4915 tree_can_duplicate_bb_p, /* can_duplicate_block_p */
4916 tree_duplicate_bb, /* duplicate_block */
4917 tree_split_edge, /* split_edge */
4918 tree_make_forwarder_block, /* make_forward_block */
4919 NULL, /* tidy_fallthru_edge */
4920 tree_block_ends_with_call_p, /* block_ends_with_call_p */
4921 tree_block_ends_with_condjump_p, /* block_ends_with_condjump_p */
4922 tree_flow_call_edges_add, /* flow_call_edges_add */
4923 tree_execute_on_growing_pred, /* execute_on_growing_pred */
4924 tree_execute_on_shrinking_pred, /* execute_on_shrinking_pred */
4925 tree_duplicate_loop_to_header_edge, /* duplicate loop for trees */
4926 tree_lv_add_condition_to_bb, /* lv_add_condition_to_bb */
4927 tree_lv_adjust_loop_header_phi, /* lv_adjust_loop_header_phi*/
4928 extract_true_false_edges_from_block, /* extract_cond_bb_edges */
4929 flush_pending_stmts /* flush_pending_stmts */
4933 /* Split all critical edges. */
4936 split_critical_edges (void)
4942 /* split_edge can redirect edges out of SWITCH_EXPRs, which can get
4943 expensive. So we want to enable recording of edge to CASE_LABEL_EXPR
4944 mappings around the calls to split_edge. */
4945 start_recording_case_labels ();
4948 FOR_EACH_EDGE (e, ei, bb->succs)
4949 if (EDGE_CRITICAL_P (e) && !(e->flags & EDGE_ABNORMAL))
4954 end_recording_case_labels ();
4957 struct tree_opt_pass pass_split_crit_edges =
4959 "crited", /* name */
4961 split_critical_edges, /* execute */
4964 0, /* static_pass_number */
4965 TV_TREE_SPLIT_EDGES, /* tv_id */
4966 PROP_cfg, /* properties required */
4967 PROP_no_crit_edges, /* properties_provided */
4968 0, /* properties_destroyed */
4969 0, /* todo_flags_start */
4970 TODO_dump_func, /* todo_flags_finish */
4975 /* Return EXP if it is a valid GIMPLE rvalue, else gimplify it into
4976 a temporary, make sure and register it to be renamed if necessary,
4977 and finally return the temporary. Put the statements to compute
4978 EXP before the current statement in BSI. */
4981 gimplify_val (block_stmt_iterator *bsi, tree type, tree exp)
4983 tree t, new_stmt, orig_stmt;
4985 if (is_gimple_val (exp))
4988 t = make_rename_temp (type, NULL);
4989 new_stmt = build (MODIFY_EXPR, type, t, exp);
4991 orig_stmt = bsi_stmt (*bsi);
4992 SET_EXPR_LOCUS (new_stmt, EXPR_LOCUS (orig_stmt));
4993 TREE_BLOCK (new_stmt) = TREE_BLOCK (orig_stmt);
4995 bsi_insert_before (bsi, new_stmt, BSI_SAME_STMT);
5000 /* Build a ternary operation and gimplify it. Emit code before BSI.
5001 Return the gimple_val holding the result. */
5004 gimplify_build3 (block_stmt_iterator *bsi, enum tree_code code,
5005 tree type, tree a, tree b, tree c)
5009 ret = fold_build3 (code, type, a, b, c);
5012 return gimplify_val (bsi, type, ret);
5015 /* Build a binary operation and gimplify it. Emit code before BSI.
5016 Return the gimple_val holding the result. */
5019 gimplify_build2 (block_stmt_iterator *bsi, enum tree_code code,
5020 tree type, tree a, tree b)
5024 ret = fold_build2 (code, type, a, b);
5027 return gimplify_val (bsi, type, ret);
5030 /* Build a unary operation and gimplify it. Emit code before BSI.
5031 Return the gimple_val holding the result. */
5034 gimplify_build1 (block_stmt_iterator *bsi, enum tree_code code, tree type,
5039 ret = fold_build1 (code, type, a);
5042 return gimplify_val (bsi, type, ret);
5047 /* Emit return warnings. */
5050 execute_warn_function_return (void)
5052 #ifdef USE_MAPPED_LOCATION
5053 source_location location;
5061 /* If we have a path to EXIT, then we do return. */
5062 if (TREE_THIS_VOLATILE (cfun->decl)
5063 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) > 0)
5065 #ifdef USE_MAPPED_LOCATION
5066 location = UNKNOWN_LOCATION;
5070 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
5072 last = last_stmt (e->src);
5073 if (TREE_CODE (last) == RETURN_EXPR
5074 #ifdef USE_MAPPED_LOCATION
5075 && (location = EXPR_LOCATION (last)) != UNKNOWN_LOCATION)
5077 && (locus = EXPR_LOCUS (last)) != NULL)
5081 #ifdef USE_MAPPED_LOCATION
5082 if (location == UNKNOWN_LOCATION)
5083 location = cfun->function_end_locus;
5084 warning (0, "%H%<noreturn%> function does return", &location);
5087 locus = &cfun->function_end_locus;
5088 warning (0, "%H%<noreturn%> function does return", locus);
5092 /* If we see "return;" in some basic block, then we do reach the end
5093 without returning a value. */
5094 else if (warn_return_type
5095 && !TREE_NO_WARNING (cfun->decl)
5096 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) > 0
5097 && !VOID_TYPE_P (TREE_TYPE (TREE_TYPE (cfun->decl))))
5099 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
5101 tree last = last_stmt (e->src);
5102 if (TREE_CODE (last) == RETURN_EXPR
5103 && TREE_OPERAND (last, 0) == NULL)
5105 #ifdef USE_MAPPED_LOCATION
5106 location = EXPR_LOCATION (last);
5107 if (location == UNKNOWN_LOCATION)
5108 location = cfun->function_end_locus;
5109 warning (0, "%Hcontrol reaches end of non-void function", &location);
5111 locus = EXPR_LOCUS (last);
5113 locus = &cfun->function_end_locus;
5114 warning (0, "%Hcontrol reaches end of non-void function", locus);
5116 TREE_NO_WARNING (cfun->decl) = 1;
5124 /* Given a basic block B which ends with a conditional and has
5125 precisely two successors, determine which of the edges is taken if
5126 the conditional is true and which is taken if the conditional is
5127 false. Set TRUE_EDGE and FALSE_EDGE appropriately. */
5130 extract_true_false_edges_from_block (basic_block b,
5134 edge e = EDGE_SUCC (b, 0);
5136 if (e->flags & EDGE_TRUE_VALUE)
5139 *false_edge = EDGE_SUCC (b, 1);
5144 *true_edge = EDGE_SUCC (b, 1);
5148 struct tree_opt_pass pass_warn_function_return =
5152 execute_warn_function_return, /* execute */
5155 0, /* static_pass_number */
5157 PROP_cfg, /* properties_required */
5158 0, /* properties_provided */
5159 0, /* properties_destroyed */
5160 0, /* todo_flags_start */
5161 0, /* todo_flags_finish */
5165 /* Emit noreturn warnings. */
5168 execute_warn_function_noreturn (void)
5170 if (warn_missing_noreturn
5171 && !TREE_THIS_VOLATILE (cfun->decl)
5172 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) == 0
5173 && !lang_hooks.function.missing_noreturn_ok_p (cfun->decl))
5174 warning (OPT_Wmissing_noreturn, "%Jfunction might be possible candidate "
5175 "for attribute %<noreturn%>",
5179 struct tree_opt_pass pass_warn_function_noreturn =
5183 execute_warn_function_noreturn, /* execute */
5186 0, /* static_pass_number */
5188 PROP_cfg, /* properties_required */
5189 0, /* properties_provided */
5190 0, /* properties_destroyed */
5191 0, /* todo_flags_start */
5192 0, /* todo_flags_finish */