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);
1276 mark_new_vars_to_rename (stmt);
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 all single-valued PHI nodes from block B of the form
1308 V_i = PHI <V_j> by propagating V_j to all the uses of V_i. */
1310 for (phi = phi_nodes (b); phi; phi = phi_nodes (b))
1312 tree def = PHI_RESULT (phi), use = PHI_ARG_DEF (phi, 0);
1315 if (!may_propagate_copy (def, use))
1317 gcc_assert (is_gimple_reg (def));
1319 /* Note that just emitting the copies is fine -- there is no problem
1320 with ordering of phi nodes. This is because A is the single
1321 predecessor of B, therefore results of the phi nodes cannot
1322 appear as arguments of the phi nodes. */
1323 copy = build2 (MODIFY_EXPR, void_type_node, def, use);
1324 bsi_insert_after (&bsi, copy, BSI_NEW_STMT);
1325 SET_PHI_RESULT (phi, NULL_TREE);
1326 SSA_NAME_DEF_STMT (def) = copy;
1329 replace_uses_by (def, use);
1331 remove_phi_node (phi, NULL);
1334 /* Ensure that B follows A. */
1335 move_block_after (b, a);
1337 gcc_assert (single_succ_edge (a)->flags & EDGE_FALLTHRU);
1338 gcc_assert (!last_stmt (a) || !stmt_ends_bb_p (last_stmt (a)));
1340 /* Remove labels from B and set bb_for_stmt to A for other statements. */
1341 for (bsi = bsi_start (b); !bsi_end_p (bsi);)
1343 if (TREE_CODE (bsi_stmt (bsi)) == LABEL_EXPR)
1345 tree label = bsi_stmt (bsi);
1348 /* Now that we can thread computed gotos, we might have
1349 a situation where we have a forced label in block B
1350 However, the label at the start of block B might still be
1351 used in other ways (think about the runtime checking for
1352 Fortran assigned gotos). So we can not just delete the
1353 label. Instead we move the label to the start of block A. */
1354 if (FORCED_LABEL (LABEL_EXPR_LABEL (label)))
1356 block_stmt_iterator dest_bsi = bsi_start (a);
1357 bsi_insert_before (&dest_bsi, label, BSI_NEW_STMT);
1362 set_bb_for_stmt (bsi_stmt (bsi), a);
1367 /* Merge the chains. */
1368 last = tsi_last (a->stmt_list);
1369 tsi_link_after (&last, b->stmt_list, TSI_NEW_STMT);
1370 b->stmt_list = NULL;
1374 /* Walk the function tree removing unnecessary statements.
1376 * Empty statement nodes are removed
1378 * Unnecessary TRY_FINALLY and TRY_CATCH blocks are removed
1380 * Unnecessary COND_EXPRs are removed
1382 * Some unnecessary BIND_EXPRs are removed
1384 Clearly more work could be done. The trick is doing the analysis
1385 and removal fast enough to be a net improvement in compile times.
1387 Note that when we remove a control structure such as a COND_EXPR
1388 BIND_EXPR, or TRY block, we will need to repeat this optimization pass
1389 to ensure we eliminate all the useless code. */
1400 static void remove_useless_stmts_1 (tree *, struct rus_data *);
1403 remove_useless_stmts_warn_notreached (tree stmt)
1405 if (EXPR_HAS_LOCATION (stmt))
1407 location_t loc = EXPR_LOCATION (stmt);
1408 if (LOCATION_LINE (loc) > 0)
1410 warning (0, "%Hwill never be executed", &loc);
1415 switch (TREE_CODE (stmt))
1417 case STATEMENT_LIST:
1419 tree_stmt_iterator i;
1420 for (i = tsi_start (stmt); !tsi_end_p (i); tsi_next (&i))
1421 if (remove_useless_stmts_warn_notreached (tsi_stmt (i)))
1427 if (remove_useless_stmts_warn_notreached (COND_EXPR_COND (stmt)))
1429 if (remove_useless_stmts_warn_notreached (COND_EXPR_THEN (stmt)))
1431 if (remove_useless_stmts_warn_notreached (COND_EXPR_ELSE (stmt)))
1435 case TRY_FINALLY_EXPR:
1436 case TRY_CATCH_EXPR:
1437 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt, 0)))
1439 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt, 1)))
1444 return remove_useless_stmts_warn_notreached (CATCH_BODY (stmt));
1445 case EH_FILTER_EXPR:
1446 return remove_useless_stmts_warn_notreached (EH_FILTER_FAILURE (stmt));
1448 return remove_useless_stmts_warn_notreached (BIND_EXPR_BLOCK (stmt));
1451 /* Not a live container. */
1459 remove_useless_stmts_cond (tree *stmt_p, struct rus_data *data)
1461 tree then_clause, else_clause, cond;
1462 bool save_has_label, then_has_label, else_has_label;
1464 save_has_label = data->has_label;
1465 data->has_label = false;
1466 data->last_goto = NULL;
1468 remove_useless_stmts_1 (&COND_EXPR_THEN (*stmt_p), data);
1470 then_has_label = data->has_label;
1471 data->has_label = false;
1472 data->last_goto = NULL;
1474 remove_useless_stmts_1 (&COND_EXPR_ELSE (*stmt_p), data);
1476 else_has_label = data->has_label;
1477 data->has_label = save_has_label | then_has_label | else_has_label;
1479 then_clause = COND_EXPR_THEN (*stmt_p);
1480 else_clause = COND_EXPR_ELSE (*stmt_p);
1481 cond = fold (COND_EXPR_COND (*stmt_p));
1483 /* If neither arm does anything at all, we can remove the whole IF. */
1484 if (!TREE_SIDE_EFFECTS (then_clause) && !TREE_SIDE_EFFECTS (else_clause))
1486 *stmt_p = build_empty_stmt ();
1487 data->repeat = true;
1490 /* If there are no reachable statements in an arm, then we can
1491 zap the entire conditional. */
1492 else if (integer_nonzerop (cond) && !else_has_label)
1494 if (warn_notreached)
1495 remove_useless_stmts_warn_notreached (else_clause);
1496 *stmt_p = then_clause;
1497 data->repeat = true;
1499 else if (integer_zerop (cond) && !then_has_label)
1501 if (warn_notreached)
1502 remove_useless_stmts_warn_notreached (then_clause);
1503 *stmt_p = else_clause;
1504 data->repeat = true;
1507 /* Check a couple of simple things on then/else with single stmts. */
1510 tree then_stmt = expr_only (then_clause);
1511 tree else_stmt = expr_only (else_clause);
1513 /* Notice branches to a common destination. */
1514 if (then_stmt && else_stmt
1515 && TREE_CODE (then_stmt) == GOTO_EXPR
1516 && TREE_CODE (else_stmt) == GOTO_EXPR
1517 && (GOTO_DESTINATION (then_stmt) == GOTO_DESTINATION (else_stmt)))
1519 *stmt_p = then_stmt;
1520 data->repeat = true;
1523 /* If the THEN/ELSE clause merely assigns a value to a variable or
1524 parameter which is already known to contain that value, then
1525 remove the useless THEN/ELSE clause. */
1526 else if (TREE_CODE (cond) == VAR_DECL || TREE_CODE (cond) == PARM_DECL)
1529 && TREE_CODE (else_stmt) == MODIFY_EXPR
1530 && TREE_OPERAND (else_stmt, 0) == cond
1531 && integer_zerop (TREE_OPERAND (else_stmt, 1)))
1532 COND_EXPR_ELSE (*stmt_p) = alloc_stmt_list ();
1534 else if ((TREE_CODE (cond) == EQ_EXPR || TREE_CODE (cond) == NE_EXPR)
1535 && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL
1536 || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL)
1537 && TREE_CONSTANT (TREE_OPERAND (cond, 1)))
1539 tree stmt = (TREE_CODE (cond) == EQ_EXPR
1540 ? then_stmt : else_stmt);
1541 tree *location = (TREE_CODE (cond) == EQ_EXPR
1542 ? &COND_EXPR_THEN (*stmt_p)
1543 : &COND_EXPR_ELSE (*stmt_p));
1546 && TREE_CODE (stmt) == MODIFY_EXPR
1547 && TREE_OPERAND (stmt, 0) == TREE_OPERAND (cond, 0)
1548 && TREE_OPERAND (stmt, 1) == TREE_OPERAND (cond, 1))
1549 *location = alloc_stmt_list ();
1553 /* Protect GOTOs in the arm of COND_EXPRs from being removed. They
1554 would be re-introduced during lowering. */
1555 data->last_goto = NULL;
1560 remove_useless_stmts_tf (tree *stmt_p, struct rus_data *data)
1562 bool save_may_branch, save_may_throw;
1563 bool this_may_branch, this_may_throw;
1565 /* Collect may_branch and may_throw information for the body only. */
1566 save_may_branch = data->may_branch;
1567 save_may_throw = data->may_throw;
1568 data->may_branch = false;
1569 data->may_throw = false;
1570 data->last_goto = NULL;
1572 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 0), data);
1574 this_may_branch = data->may_branch;
1575 this_may_throw = data->may_throw;
1576 data->may_branch |= save_may_branch;
1577 data->may_throw |= save_may_throw;
1578 data->last_goto = NULL;
1580 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 1), data);
1582 /* If the body is empty, then we can emit the FINALLY block without
1583 the enclosing TRY_FINALLY_EXPR. */
1584 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 0)))
1586 *stmt_p = TREE_OPERAND (*stmt_p, 1);
1587 data->repeat = true;
1590 /* If the handler is empty, then we can emit the TRY block without
1591 the enclosing TRY_FINALLY_EXPR. */
1592 else if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 1)))
1594 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1595 data->repeat = true;
1598 /* If the body neither throws, nor branches, then we can safely
1599 string the TRY and FINALLY blocks together. */
1600 else if (!this_may_branch && !this_may_throw)
1602 tree stmt = *stmt_p;
1603 *stmt_p = TREE_OPERAND (stmt, 0);
1604 append_to_statement_list (TREE_OPERAND (stmt, 1), stmt_p);
1605 data->repeat = true;
1611 remove_useless_stmts_tc (tree *stmt_p, struct rus_data *data)
1613 bool save_may_throw, this_may_throw;
1614 tree_stmt_iterator i;
1617 /* Collect may_throw information for the body only. */
1618 save_may_throw = data->may_throw;
1619 data->may_throw = false;
1620 data->last_goto = NULL;
1622 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 0), data);
1624 this_may_throw = data->may_throw;
1625 data->may_throw = save_may_throw;
1627 /* If the body cannot throw, then we can drop the entire TRY_CATCH_EXPR. */
1628 if (!this_may_throw)
1630 if (warn_notreached)
1631 remove_useless_stmts_warn_notreached (TREE_OPERAND (*stmt_p, 1));
1632 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1633 data->repeat = true;
1637 /* Process the catch clause specially. We may be able to tell that
1638 no exceptions propagate past this point. */
1640 this_may_throw = true;
1641 i = tsi_start (TREE_OPERAND (*stmt_p, 1));
1642 stmt = tsi_stmt (i);
1643 data->last_goto = NULL;
1645 switch (TREE_CODE (stmt))
1648 for (; !tsi_end_p (i); tsi_next (&i))
1650 stmt = tsi_stmt (i);
1651 /* If we catch all exceptions, then the body does not
1652 propagate exceptions past this point. */
1653 if (CATCH_TYPES (stmt) == NULL)
1654 this_may_throw = false;
1655 data->last_goto = NULL;
1656 remove_useless_stmts_1 (&CATCH_BODY (stmt), data);
1660 case EH_FILTER_EXPR:
1661 if (EH_FILTER_MUST_NOT_THROW (stmt))
1662 this_may_throw = false;
1663 else if (EH_FILTER_TYPES (stmt) == NULL)
1664 this_may_throw = false;
1665 remove_useless_stmts_1 (&EH_FILTER_FAILURE (stmt), data);
1669 /* Otherwise this is a cleanup. */
1670 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 1), data);
1672 /* If the cleanup is empty, then we can emit the TRY block without
1673 the enclosing TRY_CATCH_EXPR. */
1674 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 1)))
1676 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1677 data->repeat = true;
1681 data->may_throw |= this_may_throw;
1686 remove_useless_stmts_bind (tree *stmt_p, struct rus_data *data)
1690 /* First remove anything underneath the BIND_EXPR. */
1691 remove_useless_stmts_1 (&BIND_EXPR_BODY (*stmt_p), data);
1693 /* If the BIND_EXPR has no variables, then we can pull everything
1694 up one level and remove the BIND_EXPR, unless this is the toplevel
1695 BIND_EXPR for the current function or an inlined function.
1697 When this situation occurs we will want to apply this
1698 optimization again. */
1699 block = BIND_EXPR_BLOCK (*stmt_p);
1700 if (BIND_EXPR_VARS (*stmt_p) == NULL_TREE
1701 && *stmt_p != DECL_SAVED_TREE (current_function_decl)
1703 || ! BLOCK_ABSTRACT_ORIGIN (block)
1704 || (TREE_CODE (BLOCK_ABSTRACT_ORIGIN (block))
1707 *stmt_p = BIND_EXPR_BODY (*stmt_p);
1708 data->repeat = true;
1714 remove_useless_stmts_goto (tree *stmt_p, struct rus_data *data)
1716 tree dest = GOTO_DESTINATION (*stmt_p);
1718 data->may_branch = true;
1719 data->last_goto = NULL;
1721 /* Record the last goto expr, so that we can delete it if unnecessary. */
1722 if (TREE_CODE (dest) == LABEL_DECL)
1723 data->last_goto = stmt_p;
1728 remove_useless_stmts_label (tree *stmt_p, struct rus_data *data)
1730 tree label = LABEL_EXPR_LABEL (*stmt_p);
1732 data->has_label = true;
1734 /* We do want to jump across non-local label receiver code. */
1735 if (DECL_NONLOCAL (label))
1736 data->last_goto = NULL;
1738 else if (data->last_goto && GOTO_DESTINATION (*data->last_goto) == label)
1740 *data->last_goto = build_empty_stmt ();
1741 data->repeat = true;
1744 /* ??? Add something here to delete unused labels. */
1748 /* If the function is "const" or "pure", then clear TREE_SIDE_EFFECTS on its
1749 decl. This allows us to eliminate redundant or useless
1750 calls to "const" functions.
1752 Gimplifier already does the same operation, but we may notice functions
1753 being const and pure once their calls has been gimplified, so we need
1754 to update the flag. */
1757 update_call_expr_flags (tree call)
1759 tree decl = get_callee_fndecl (call);
1762 if (call_expr_flags (call) & (ECF_CONST | ECF_PURE))
1763 TREE_SIDE_EFFECTS (call) = 0;
1764 if (TREE_NOTHROW (decl))
1765 TREE_NOTHROW (call) = 1;
1769 /* T is CALL_EXPR. Set current_function_calls_* flags. */
1772 notice_special_calls (tree t)
1774 int flags = call_expr_flags (t);
1776 if (flags & ECF_MAY_BE_ALLOCA)
1777 current_function_calls_alloca = true;
1778 if (flags & ECF_RETURNS_TWICE)
1779 current_function_calls_setjmp = true;
1783 /* Clear flags set by notice_special_calls. Used by dead code removal
1784 to update the flags. */
1787 clear_special_calls (void)
1789 current_function_calls_alloca = false;
1790 current_function_calls_setjmp = false;
1795 remove_useless_stmts_1 (tree *tp, struct rus_data *data)
1799 switch (TREE_CODE (t))
1802 remove_useless_stmts_cond (tp, data);
1805 case TRY_FINALLY_EXPR:
1806 remove_useless_stmts_tf (tp, data);
1809 case TRY_CATCH_EXPR:
1810 remove_useless_stmts_tc (tp, data);
1814 remove_useless_stmts_bind (tp, data);
1818 remove_useless_stmts_goto (tp, data);
1822 remove_useless_stmts_label (tp, data);
1827 data->last_goto = NULL;
1828 data->may_branch = true;
1833 data->last_goto = NULL;
1834 notice_special_calls (t);
1835 update_call_expr_flags (t);
1836 if (tree_could_throw_p (t))
1837 data->may_throw = true;
1841 data->last_goto = NULL;
1843 op = get_call_expr_in (t);
1846 update_call_expr_flags (op);
1847 notice_special_calls (op);
1849 if (tree_could_throw_p (t))
1850 data->may_throw = true;
1853 case STATEMENT_LIST:
1855 tree_stmt_iterator i = tsi_start (t);
1856 while (!tsi_end_p (i))
1859 if (IS_EMPTY_STMT (t))
1865 remove_useless_stmts_1 (tsi_stmt_ptr (i), data);
1868 if (TREE_CODE (t) == STATEMENT_LIST)
1870 tsi_link_before (&i, t, TSI_SAME_STMT);
1880 data->last_goto = NULL;
1884 data->last_goto = NULL;
1890 remove_useless_stmts (void)
1892 struct rus_data data;
1894 clear_special_calls ();
1898 memset (&data, 0, sizeof (data));
1899 remove_useless_stmts_1 (&DECL_SAVED_TREE (current_function_decl), &data);
1901 while (data.repeat);
1905 struct tree_opt_pass pass_remove_useless_stmts =
1907 "useless", /* name */
1909 remove_useless_stmts, /* execute */
1912 0, /* static_pass_number */
1914 PROP_gimple_any, /* properties_required */
1915 0, /* properties_provided */
1916 0, /* properties_destroyed */
1917 0, /* todo_flags_start */
1918 TODO_dump_func, /* todo_flags_finish */
1922 /* Remove PHI nodes associated with basic block BB and all edges out of BB. */
1925 remove_phi_nodes_and_edges_for_unreachable_block (basic_block bb)
1929 /* Since this block is no longer reachable, we can just delete all
1930 of its PHI nodes. */
1931 phi = phi_nodes (bb);
1934 tree next = PHI_CHAIN (phi);
1935 remove_phi_node (phi, NULL_TREE);
1939 /* Remove edges to BB's successors. */
1940 while (EDGE_COUNT (bb->succs) > 0)
1941 remove_edge (EDGE_SUCC (bb, 0));
1945 /* Remove statements of basic block BB. */
1948 remove_bb (basic_block bb)
1950 block_stmt_iterator i;
1951 #ifdef USE_MAPPED_LOCATION
1952 source_location loc = UNKNOWN_LOCATION;
1954 source_locus loc = 0;
1959 fprintf (dump_file, "Removing basic block %d\n", bb->index);
1960 if (dump_flags & TDF_DETAILS)
1962 dump_bb (bb, dump_file, 0);
1963 fprintf (dump_file, "\n");
1967 /* If we remove the header or the latch of a loop, mark the loop for
1968 removal by setting its header and latch to NULL. */
1971 struct loop *loop = bb->loop_father;
1973 if (loop->latch == bb
1974 || loop->header == bb)
1977 loop->header = NULL;
1981 /* Remove all the instructions in the block. */
1982 for (i = bsi_start (bb); !bsi_end_p (i);)
1984 tree stmt = bsi_stmt (i);
1985 if (TREE_CODE (stmt) == LABEL_EXPR
1986 && (FORCED_LABEL (LABEL_EXPR_LABEL (stmt))
1987 || DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt))))
1990 block_stmt_iterator new_bsi;
1992 /* A non-reachable non-local label may still be referenced.
1993 But it no longer needs to carry the extra semantics of
1995 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)))
1997 DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)) = 0;
1998 FORCED_LABEL (LABEL_EXPR_LABEL (stmt)) = 1;
2001 new_bb = bb->prev_bb;
2002 new_bsi = bsi_start (new_bb);
2004 bsi_insert_before (&new_bsi, stmt, BSI_NEW_STMT);
2008 /* Release SSA definitions if we are in SSA. Note that we
2009 may be called when not in SSA. For example,
2010 final_cleanup calls this function via
2011 cleanup_tree_cfg. */
2013 release_defs (stmt);
2018 /* Don't warn for removed gotos. Gotos are often removed due to
2019 jump threading, thus resulting in bogus warnings. Not great,
2020 since this way we lose warnings for gotos in the original
2021 program that are indeed unreachable. */
2022 if (TREE_CODE (stmt) != GOTO_EXPR && EXPR_HAS_LOCATION (stmt) && !loc)
2024 #ifdef USE_MAPPED_LOCATION
2025 if (EXPR_HAS_LOCATION (stmt))
2026 loc = EXPR_LOCATION (stmt);
2029 t = EXPR_LOCUS (stmt);
2030 if (t && LOCATION_LINE (*t) > 0)
2036 /* If requested, give a warning that the first statement in the
2037 block is unreachable. We walk statements backwards in the
2038 loop above, so the last statement we process is the first statement
2040 #ifdef USE_MAPPED_LOCATION
2041 if (loc > BUILTINS_LOCATION)
2042 warning (OPT_Wunreachable_code, "%Hwill never be executed", &loc);
2045 warning (OPT_Wunreachable_code, "%Hwill never be executed", loc);
2048 remove_phi_nodes_and_edges_for_unreachable_block (bb);
2052 /* Given a basic block BB ending with COND_EXPR or SWITCH_EXPR, and a
2053 predicate VAL, return the edge that will be taken out of the block.
2054 If VAL does not match a unique edge, NULL is returned. */
2057 find_taken_edge (basic_block bb, tree val)
2061 stmt = last_stmt (bb);
2064 gcc_assert (is_ctrl_stmt (stmt));
2067 if (! is_gimple_min_invariant (val))
2070 if (TREE_CODE (stmt) == COND_EXPR)
2071 return find_taken_edge_cond_expr (bb, val);
2073 if (TREE_CODE (stmt) == SWITCH_EXPR)
2074 return find_taken_edge_switch_expr (bb, val);
2076 if (computed_goto_p (stmt))
2077 return find_taken_edge_computed_goto (bb, TREE_OPERAND( val, 0));
2082 /* Given a constant value VAL and the entry block BB to a GOTO_EXPR
2083 statement, determine which of the outgoing edges will be taken out of the
2084 block. Return NULL if either edge may be taken. */
2087 find_taken_edge_computed_goto (basic_block bb, tree val)
2092 dest = label_to_block (val);
2095 e = find_edge (bb, dest);
2096 gcc_assert (e != NULL);
2102 /* Given a constant value VAL and the entry block BB to a COND_EXPR
2103 statement, determine which of the two edges will be taken out of the
2104 block. Return NULL if either edge may be taken. */
2107 find_taken_edge_cond_expr (basic_block bb, tree val)
2109 edge true_edge, false_edge;
2111 extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
2113 gcc_assert (TREE_CODE (val) == INTEGER_CST);
2114 return (zero_p (val) ? false_edge : true_edge);
2117 /* Given an INTEGER_CST VAL and the entry block BB to a SWITCH_EXPR
2118 statement, determine which edge will be taken out of the block. Return
2119 NULL if any edge may be taken. */
2122 find_taken_edge_switch_expr (basic_block bb, tree val)
2124 tree switch_expr, taken_case;
2125 basic_block dest_bb;
2128 switch_expr = last_stmt (bb);
2129 taken_case = find_case_label_for_value (switch_expr, val);
2130 dest_bb = label_to_block (CASE_LABEL (taken_case));
2132 e = find_edge (bb, dest_bb);
2138 /* Return the CASE_LABEL_EXPR that SWITCH_EXPR will take for VAL.
2139 We can make optimal use here of the fact that the case labels are
2140 sorted: We can do a binary search for a case matching VAL. */
2143 find_case_label_for_value (tree switch_expr, tree val)
2145 tree vec = SWITCH_LABELS (switch_expr);
2146 size_t low, high, n = TREE_VEC_LENGTH (vec);
2147 tree default_case = TREE_VEC_ELT (vec, n - 1);
2149 for (low = -1, high = n - 1; high - low > 1; )
2151 size_t i = (high + low) / 2;
2152 tree t = TREE_VEC_ELT (vec, i);
2155 /* Cache the result of comparing CASE_LOW and val. */
2156 cmp = tree_int_cst_compare (CASE_LOW (t), val);
2163 if (CASE_HIGH (t) == NULL)
2165 /* A singe-valued case label. */
2171 /* A case range. We can only handle integer ranges. */
2172 if (cmp <= 0 && tree_int_cst_compare (CASE_HIGH (t), val) >= 0)
2177 return default_case;
2183 /*---------------------------------------------------------------------------
2185 ---------------------------------------------------------------------------*/
2187 /* Dump tree-specific information of block BB to file OUTF. */
2190 tree_dump_bb (basic_block bb, FILE *outf, int indent)
2192 dump_generic_bb (outf, bb, indent, TDF_VOPS);
2196 /* Dump a basic block on stderr. */
2199 debug_tree_bb (basic_block bb)
2201 dump_bb (bb, stderr, 0);
2205 /* Dump basic block with index N on stderr. */
2208 debug_tree_bb_n (int n)
2210 debug_tree_bb (BASIC_BLOCK (n));
2211 return BASIC_BLOCK (n);
2215 /* Dump the CFG on stderr.
2217 FLAGS are the same used by the tree dumping functions
2218 (see TDF_* in tree.h). */
2221 debug_tree_cfg (int flags)
2223 dump_tree_cfg (stderr, flags);
2227 /* Dump the program showing basic block boundaries on the given FILE.
2229 FLAGS are the same used by the tree dumping functions (see TDF_* in
2233 dump_tree_cfg (FILE *file, int flags)
2235 if (flags & TDF_DETAILS)
2237 const char *funcname
2238 = lang_hooks.decl_printable_name (current_function_decl, 2);
2241 fprintf (file, ";; Function %s\n\n", funcname);
2242 fprintf (file, ";; \n%d basic blocks, %d edges, last basic block %d.\n\n",
2243 n_basic_blocks, n_edges, last_basic_block);
2245 brief_dump_cfg (file);
2246 fprintf (file, "\n");
2249 if (flags & TDF_STATS)
2250 dump_cfg_stats (file);
2252 dump_function_to_file (current_function_decl, file, flags | TDF_BLOCKS);
2256 /* Dump CFG statistics on FILE. */
2259 dump_cfg_stats (FILE *file)
2261 static long max_num_merged_labels = 0;
2262 unsigned long size, total = 0;
2265 const char * const fmt_str = "%-30s%-13s%12s\n";
2266 const char * const fmt_str_1 = "%-30s%13d%11lu%c\n";
2267 const char * const fmt_str_2 = "%-30s%13ld%11lu%c\n";
2268 const char * const fmt_str_3 = "%-43s%11lu%c\n";
2269 const char *funcname
2270 = lang_hooks.decl_printable_name (current_function_decl, 2);
2273 fprintf (file, "\nCFG Statistics for %s\n\n", funcname);
2275 fprintf (file, "---------------------------------------------------------\n");
2276 fprintf (file, fmt_str, "", " Number of ", "Memory");
2277 fprintf (file, fmt_str, "", " instances ", "used ");
2278 fprintf (file, "---------------------------------------------------------\n");
2280 size = n_basic_blocks * sizeof (struct basic_block_def);
2282 fprintf (file, fmt_str_1, "Basic blocks", n_basic_blocks,
2283 SCALE (size), LABEL (size));
2287 num_edges += EDGE_COUNT (bb->succs);
2288 size = num_edges * sizeof (struct edge_def);
2290 fprintf (file, fmt_str_2, "Edges", num_edges, SCALE (size), LABEL (size));
2292 fprintf (file, "---------------------------------------------------------\n");
2293 fprintf (file, fmt_str_3, "Total memory used by CFG data", SCALE (total),
2295 fprintf (file, "---------------------------------------------------------\n");
2296 fprintf (file, "\n");
2298 if (cfg_stats.num_merged_labels > max_num_merged_labels)
2299 max_num_merged_labels = cfg_stats.num_merged_labels;
2301 fprintf (file, "Coalesced label blocks: %ld (Max so far: %ld)\n",
2302 cfg_stats.num_merged_labels, max_num_merged_labels);
2304 fprintf (file, "\n");
2308 /* Dump CFG statistics on stderr. Keep extern so that it's always
2309 linked in the final executable. */
2312 debug_cfg_stats (void)
2314 dump_cfg_stats (stderr);
2318 /* Dump the flowgraph to a .vcg FILE. */
2321 tree_cfg2vcg (FILE *file)
2326 const char *funcname
2327 = lang_hooks.decl_printable_name (current_function_decl, 2);
2329 /* Write the file header. */
2330 fprintf (file, "graph: { title: \"%s\"\n", funcname);
2331 fprintf (file, "node: { title: \"ENTRY\" label: \"ENTRY\" }\n");
2332 fprintf (file, "node: { title: \"EXIT\" label: \"EXIT\" }\n");
2334 /* Write blocks and edges. */
2335 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
2337 fprintf (file, "edge: { sourcename: \"ENTRY\" targetname: \"%d\"",
2340 if (e->flags & EDGE_FAKE)
2341 fprintf (file, " linestyle: dotted priority: 10");
2343 fprintf (file, " linestyle: solid priority: 100");
2345 fprintf (file, " }\n");
2351 enum tree_code head_code, end_code;
2352 const char *head_name, *end_name;
2355 tree first = first_stmt (bb);
2356 tree last = last_stmt (bb);
2360 head_code = TREE_CODE (first);
2361 head_name = tree_code_name[head_code];
2362 head_line = get_lineno (first);
2365 head_name = "no-statement";
2369 end_code = TREE_CODE (last);
2370 end_name = tree_code_name[end_code];
2371 end_line = get_lineno (last);
2374 end_name = "no-statement";
2376 fprintf (file, "node: { title: \"%d\" label: \"#%d\\n%s (%d)\\n%s (%d)\"}\n",
2377 bb->index, bb->index, head_name, head_line, end_name,
2380 FOR_EACH_EDGE (e, ei, bb->succs)
2382 if (e->dest == EXIT_BLOCK_PTR)
2383 fprintf (file, "edge: { sourcename: \"%d\" targetname: \"EXIT\"", bb->index);
2385 fprintf (file, "edge: { sourcename: \"%d\" targetname: \"%d\"", bb->index, e->dest->index);
2387 if (e->flags & EDGE_FAKE)
2388 fprintf (file, " priority: 10 linestyle: dotted");
2390 fprintf (file, " priority: 100 linestyle: solid");
2392 fprintf (file, " }\n");
2395 if (bb->next_bb != EXIT_BLOCK_PTR)
2399 fputs ("}\n\n", file);
2404 /*---------------------------------------------------------------------------
2405 Miscellaneous helpers
2406 ---------------------------------------------------------------------------*/
2408 /* Return true if T represents a stmt that always transfers control. */
2411 is_ctrl_stmt (tree t)
2413 return (TREE_CODE (t) == COND_EXPR
2414 || TREE_CODE (t) == SWITCH_EXPR
2415 || TREE_CODE (t) == GOTO_EXPR
2416 || TREE_CODE (t) == RETURN_EXPR
2417 || TREE_CODE (t) == RESX_EXPR);
2421 /* Return true if T is a statement that may alter the flow of control
2422 (e.g., a call to a non-returning function). */
2425 is_ctrl_altering_stmt (tree t)
2430 call = get_call_expr_in (t);
2433 /* A non-pure/const CALL_EXPR alters flow control if the current
2434 function has nonlocal labels. */
2435 if (TREE_SIDE_EFFECTS (call) && current_function_has_nonlocal_label)
2438 /* A CALL_EXPR also alters control flow if it does not return. */
2439 if (call_expr_flags (call) & ECF_NORETURN)
2443 /* If a statement can throw, it alters control flow. */
2444 return tree_can_throw_internal (t);
2448 /* Return true if T is a computed goto. */
2451 computed_goto_p (tree t)
2453 return (TREE_CODE (t) == GOTO_EXPR
2454 && TREE_CODE (GOTO_DESTINATION (t)) != LABEL_DECL);
2458 /* Checks whether EXPR is a simple local goto. */
2461 simple_goto_p (tree expr)
2463 return (TREE_CODE (expr) == GOTO_EXPR
2464 && TREE_CODE (GOTO_DESTINATION (expr)) == LABEL_DECL);
2468 /* Return true if T should start a new basic block. PREV_T is the
2469 statement preceding T. It is used when T is a label or a case label.
2470 Labels should only start a new basic block if their previous statement
2471 wasn't a label. Otherwise, sequence of labels would generate
2472 unnecessary basic blocks that only contain a single label. */
2475 stmt_starts_bb_p (tree t, tree prev_t)
2480 /* LABEL_EXPRs start a new basic block only if the preceding
2481 statement wasn't a label of the same type. This prevents the
2482 creation of consecutive blocks that have nothing but a single
2484 if (TREE_CODE (t) == LABEL_EXPR)
2486 /* Nonlocal and computed GOTO targets always start a new block. */
2487 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (t))
2488 || FORCED_LABEL (LABEL_EXPR_LABEL (t)))
2491 if (prev_t && TREE_CODE (prev_t) == LABEL_EXPR)
2493 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (prev_t)))
2496 cfg_stats.num_merged_labels++;
2507 /* Return true if T should end a basic block. */
2510 stmt_ends_bb_p (tree t)
2512 return is_ctrl_stmt (t) || is_ctrl_altering_stmt (t);
2516 /* Add gotos that used to be represented implicitly in the CFG. */
2519 disband_implicit_edges (void)
2522 block_stmt_iterator last;
2529 last = bsi_last (bb);
2530 stmt = last_stmt (bb);
2532 if (stmt && TREE_CODE (stmt) == COND_EXPR)
2534 /* Remove superfluous gotos from COND_EXPR branches. Moved
2535 from cfg_remove_useless_stmts here since it violates the
2536 invariants for tree--cfg correspondence and thus fits better
2537 here where we do it anyway. */
2538 e = find_edge (bb, bb->next_bb);
2541 if (e->flags & EDGE_TRUE_VALUE)
2542 COND_EXPR_THEN (stmt) = build_empty_stmt ();
2543 else if (e->flags & EDGE_FALSE_VALUE)
2544 COND_EXPR_ELSE (stmt) = build_empty_stmt ();
2547 e->flags |= EDGE_FALLTHRU;
2553 if (stmt && TREE_CODE (stmt) == RETURN_EXPR)
2555 /* Remove the RETURN_EXPR if we may fall though to the exit
2557 gcc_assert (single_succ_p (bb));
2558 gcc_assert (single_succ (bb) == EXIT_BLOCK_PTR);
2560 if (bb->next_bb == EXIT_BLOCK_PTR
2561 && !TREE_OPERAND (stmt, 0))
2564 single_succ_edge (bb)->flags |= EDGE_FALLTHRU;
2569 /* There can be no fallthru edge if the last statement is a control
2571 if (stmt && is_ctrl_stmt (stmt))
2574 /* Find a fallthru edge and emit the goto if necessary. */
2575 FOR_EACH_EDGE (e, ei, bb->succs)
2576 if (e->flags & EDGE_FALLTHRU)
2579 if (!e || e->dest == bb->next_bb)
2582 gcc_assert (e->dest != EXIT_BLOCK_PTR);
2583 label = tree_block_label (e->dest);
2585 stmt = build1 (GOTO_EXPR, void_type_node, label);
2586 #ifdef USE_MAPPED_LOCATION
2587 SET_EXPR_LOCATION (stmt, e->goto_locus);
2589 SET_EXPR_LOCUS (stmt, e->goto_locus);
2591 bsi_insert_after (&last, stmt, BSI_NEW_STMT);
2592 e->flags &= ~EDGE_FALLTHRU;
2596 /* Remove block annotations and other datastructures. */
2599 delete_tree_cfg_annotations (void)
2601 label_to_block_map = NULL;
2605 /* Return the first statement in basic block BB. */
2608 first_stmt (basic_block bb)
2610 block_stmt_iterator i = bsi_start (bb);
2611 return !bsi_end_p (i) ? bsi_stmt (i) : NULL_TREE;
2615 /* Return the last statement in basic block BB. */
2618 last_stmt (basic_block bb)
2620 block_stmt_iterator b = bsi_last (bb);
2621 return !bsi_end_p (b) ? bsi_stmt (b) : NULL_TREE;
2625 /* Return a pointer to the last statement in block BB. */
2628 last_stmt_ptr (basic_block bb)
2630 block_stmt_iterator last = bsi_last (bb);
2631 return !bsi_end_p (last) ? bsi_stmt_ptr (last) : NULL;
2635 /* Return the last statement of an otherwise empty block. Return NULL
2636 if the block is totally empty, or if it contains more than one
2640 last_and_only_stmt (basic_block bb)
2642 block_stmt_iterator i = bsi_last (bb);
2648 last = bsi_stmt (i);
2653 /* Empty statements should no longer appear in the instruction stream.
2654 Everything that might have appeared before should be deleted by
2655 remove_useless_stmts, and the optimizers should just bsi_remove
2656 instead of smashing with build_empty_stmt.
2658 Thus the only thing that should appear here in a block containing
2659 one executable statement is a label. */
2660 prev = bsi_stmt (i);
2661 if (TREE_CODE (prev) == LABEL_EXPR)
2668 /* Mark BB as the basic block holding statement T. */
2671 set_bb_for_stmt (tree t, basic_block bb)
2673 if (TREE_CODE (t) == PHI_NODE)
2675 else if (TREE_CODE (t) == STATEMENT_LIST)
2677 tree_stmt_iterator i;
2678 for (i = tsi_start (t); !tsi_end_p (i); tsi_next (&i))
2679 set_bb_for_stmt (tsi_stmt (i), bb);
2683 stmt_ann_t ann = get_stmt_ann (t);
2686 /* If the statement is a label, add the label to block-to-labels map
2687 so that we can speed up edge creation for GOTO_EXPRs. */
2688 if (TREE_CODE (t) == LABEL_EXPR)
2692 t = LABEL_EXPR_LABEL (t);
2693 uid = LABEL_DECL_UID (t);
2696 LABEL_DECL_UID (t) = uid = cfun->last_label_uid++;
2697 if (VARRAY_SIZE (label_to_block_map) <= (unsigned) uid)
2698 VARRAY_GROW (label_to_block_map, 3 * uid / 2);
2701 /* We're moving an existing label. Make sure that we've
2702 removed it from the old block. */
2703 gcc_assert (!bb || !VARRAY_BB (label_to_block_map, uid));
2704 VARRAY_BB (label_to_block_map, uid) = bb;
2709 /* Finds iterator for STMT. */
2711 extern block_stmt_iterator
2712 bsi_for_stmt (tree stmt)
2714 block_stmt_iterator bsi;
2716 for (bsi = bsi_start (bb_for_stmt (stmt)); !bsi_end_p (bsi); bsi_next (&bsi))
2717 if (bsi_stmt (bsi) == stmt)
2723 /* Mark statement T as modified, and update it. */
2725 update_modified_stmts (tree t)
2727 if (TREE_CODE (t) == STATEMENT_LIST)
2729 tree_stmt_iterator i;
2731 for (i = tsi_start (t); !tsi_end_p (i); tsi_next (&i))
2733 stmt = tsi_stmt (i);
2734 update_stmt_if_modified (stmt);
2738 update_stmt_if_modified (t);
2741 /* Insert statement (or statement list) T before the statement
2742 pointed-to by iterator I. M specifies how to update iterator I
2743 after insertion (see enum bsi_iterator_update). */
2746 bsi_insert_before (block_stmt_iterator *i, tree t, enum bsi_iterator_update m)
2748 set_bb_for_stmt (t, i->bb);
2749 update_modified_stmts (t);
2750 tsi_link_before (&i->tsi, t, m);
2754 /* Insert statement (or statement list) T after the statement
2755 pointed-to by iterator I. M specifies how to update iterator I
2756 after insertion (see enum bsi_iterator_update). */
2759 bsi_insert_after (block_stmt_iterator *i, tree t, enum bsi_iterator_update m)
2761 set_bb_for_stmt (t, i->bb);
2762 update_modified_stmts (t);
2763 tsi_link_after (&i->tsi, t, m);
2767 /* Remove the statement pointed to by iterator I. The iterator is updated
2768 to the next statement. */
2771 bsi_remove (block_stmt_iterator *i)
2773 tree t = bsi_stmt (*i);
2774 set_bb_for_stmt (t, NULL);
2775 delink_stmt_imm_use (t);
2776 tsi_delink (&i->tsi);
2777 mark_stmt_modified (t);
2781 /* Move the statement at FROM so it comes right after the statement at TO. */
2784 bsi_move_after (block_stmt_iterator *from, block_stmt_iterator *to)
2786 tree stmt = bsi_stmt (*from);
2788 bsi_insert_after (to, stmt, BSI_SAME_STMT);
2792 /* Move the statement at FROM so it comes right before the statement at TO. */
2795 bsi_move_before (block_stmt_iterator *from, block_stmt_iterator *to)
2797 tree stmt = bsi_stmt (*from);
2799 bsi_insert_before (to, stmt, BSI_SAME_STMT);
2803 /* Move the statement at FROM to the end of basic block BB. */
2806 bsi_move_to_bb_end (block_stmt_iterator *from, basic_block bb)
2808 block_stmt_iterator last = bsi_last (bb);
2810 /* Have to check bsi_end_p because it could be an empty block. */
2811 if (!bsi_end_p (last) && is_ctrl_stmt (bsi_stmt (last)))
2812 bsi_move_before (from, &last);
2814 bsi_move_after (from, &last);
2818 /* Replace the contents of the statement pointed to by iterator BSI
2819 with STMT. If PRESERVE_EH_INFO is true, the exception handling
2820 information of the original statement is preserved. */
2823 bsi_replace (const block_stmt_iterator *bsi, tree stmt, bool preserve_eh_info)
2826 tree orig_stmt = bsi_stmt (*bsi);
2828 SET_EXPR_LOCUS (stmt, EXPR_LOCUS (orig_stmt));
2829 set_bb_for_stmt (stmt, bsi->bb);
2831 /* Preserve EH region information from the original statement, if
2832 requested by the caller. */
2833 if (preserve_eh_info)
2835 eh_region = lookup_stmt_eh_region (orig_stmt);
2837 add_stmt_to_eh_region (stmt, eh_region);
2840 delink_stmt_imm_use (orig_stmt);
2841 *bsi_stmt_ptr (*bsi) = stmt;
2842 mark_stmt_modified (stmt);
2843 update_modified_stmts (stmt);
2847 /* Insert the statement pointed-to by BSI into edge E. Every attempt
2848 is made to place the statement in an existing basic block, but
2849 sometimes that isn't possible. When it isn't possible, the edge is
2850 split and the statement is added to the new block.
2852 In all cases, the returned *BSI points to the correct location. The
2853 return value is true if insertion should be done after the location,
2854 or false if it should be done before the location. If new basic block
2855 has to be created, it is stored in *NEW_BB. */
2858 tree_find_edge_insert_loc (edge e, block_stmt_iterator *bsi,
2859 basic_block *new_bb)
2861 basic_block dest, src;
2867 /* If the destination has one predecessor which has no PHI nodes,
2868 insert there. Except for the exit block.
2870 The requirement for no PHI nodes could be relaxed. Basically we
2871 would have to examine the PHIs to prove that none of them used
2872 the value set by the statement we want to insert on E. That
2873 hardly seems worth the effort. */
2874 if (single_pred_p (dest)
2875 && ! phi_nodes (dest)
2876 && dest != EXIT_BLOCK_PTR)
2878 *bsi = bsi_start (dest);
2879 if (bsi_end_p (*bsi))
2882 /* Make sure we insert after any leading labels. */
2883 tmp = bsi_stmt (*bsi);
2884 while (TREE_CODE (tmp) == LABEL_EXPR)
2887 if (bsi_end_p (*bsi))
2889 tmp = bsi_stmt (*bsi);
2892 if (bsi_end_p (*bsi))
2894 *bsi = bsi_last (dest);
2901 /* If the source has one successor, the edge is not abnormal and
2902 the last statement does not end a basic block, insert there.
2903 Except for the entry block. */
2905 if ((e->flags & EDGE_ABNORMAL) == 0
2906 && single_succ_p (src)
2907 && src != ENTRY_BLOCK_PTR)
2909 *bsi = bsi_last (src);
2910 if (bsi_end_p (*bsi))
2913 tmp = bsi_stmt (*bsi);
2914 if (!stmt_ends_bb_p (tmp))
2917 /* Insert code just before returning the value. We may need to decompose
2918 the return in the case it contains non-trivial operand. */
2919 if (TREE_CODE (tmp) == RETURN_EXPR)
2921 tree op = TREE_OPERAND (tmp, 0);
2922 if (!is_gimple_val (op))
2924 gcc_assert (TREE_CODE (op) == MODIFY_EXPR);
2925 bsi_insert_before (bsi, op, BSI_NEW_STMT);
2926 TREE_OPERAND (tmp, 0) = TREE_OPERAND (op, 0);
2933 /* Otherwise, create a new basic block, and split this edge. */
2934 dest = split_edge (e);
2937 e = single_pred_edge (dest);
2942 /* This routine will commit all pending edge insertions, creating any new
2943 basic blocks which are necessary. */
2946 bsi_commit_edge_inserts (void)
2952 bsi_commit_one_edge_insert (single_succ_edge (ENTRY_BLOCK_PTR), NULL);
2955 FOR_EACH_EDGE (e, ei, bb->succs)
2956 bsi_commit_one_edge_insert (e, NULL);
2960 /* Commit insertions pending at edge E. If a new block is created, set NEW_BB
2961 to this block, otherwise set it to NULL. */
2964 bsi_commit_one_edge_insert (edge e, basic_block *new_bb)
2968 if (PENDING_STMT (e))
2970 block_stmt_iterator bsi;
2971 tree stmt = PENDING_STMT (e);
2973 PENDING_STMT (e) = NULL_TREE;
2975 if (tree_find_edge_insert_loc (e, &bsi, new_bb))
2976 bsi_insert_after (&bsi, stmt, BSI_NEW_STMT);
2978 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
2983 /* Add STMT to the pending list of edge E. No actual insertion is
2984 made until a call to bsi_commit_edge_inserts () is made. */
2987 bsi_insert_on_edge (edge e, tree stmt)
2989 append_to_statement_list (stmt, &PENDING_STMT (e));
2992 /* Similar to bsi_insert_on_edge+bsi_commit_edge_inserts. If a new
2993 block has to be created, it is returned. */
2996 bsi_insert_on_edge_immediate (edge e, tree stmt)
2998 block_stmt_iterator bsi;
2999 basic_block new_bb = NULL;
3001 gcc_assert (!PENDING_STMT (e));
3003 if (tree_find_edge_insert_loc (e, &bsi, &new_bb))
3004 bsi_insert_after (&bsi, stmt, BSI_NEW_STMT);
3006 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
3011 /*---------------------------------------------------------------------------
3012 Tree specific functions for CFG manipulation
3013 ---------------------------------------------------------------------------*/
3015 /* Reinstall those PHI arguments queued in OLD_EDGE to NEW_EDGE. */
3018 reinstall_phi_args (edge new_edge, edge old_edge)
3022 if (!PENDING_STMT (old_edge))
3025 for (var = PENDING_STMT (old_edge), phi = phi_nodes (new_edge->dest);
3027 var = TREE_CHAIN (var), phi = PHI_CHAIN (phi))
3029 tree result = TREE_PURPOSE (var);
3030 tree arg = TREE_VALUE (var);
3032 gcc_assert (result == PHI_RESULT (phi));
3034 add_phi_arg (phi, arg, new_edge);
3037 PENDING_STMT (old_edge) = NULL;
3040 /* Returns the basic block after that the new basic block created
3041 by splitting edge EDGE_IN should be placed. Tries to keep the new block
3042 near its "logical" location. This is of most help to humans looking
3043 at debugging dumps. */
3046 split_edge_bb_loc (edge edge_in)
3048 basic_block dest = edge_in->dest;
3050 if (dest->prev_bb && find_edge (dest->prev_bb, dest))
3051 return edge_in->src;
3053 return dest->prev_bb;
3056 /* Split a (typically critical) edge EDGE_IN. Return the new block.
3057 Abort on abnormal edges. */
3060 tree_split_edge (edge edge_in)
3062 basic_block new_bb, after_bb, dest, src;
3065 /* Abnormal edges cannot be split. */
3066 gcc_assert (!(edge_in->flags & EDGE_ABNORMAL));
3069 dest = edge_in->dest;
3071 after_bb = split_edge_bb_loc (edge_in);
3073 new_bb = create_empty_bb (after_bb);
3074 new_bb->frequency = EDGE_FREQUENCY (edge_in);
3075 new_bb->count = edge_in->count;
3076 new_edge = make_edge (new_bb, dest, EDGE_FALLTHRU);
3077 new_edge->probability = REG_BR_PROB_BASE;
3078 new_edge->count = edge_in->count;
3080 e = redirect_edge_and_branch (edge_in, new_bb);
3082 reinstall_phi_args (new_edge, e);
3088 /* Return true when BB has label LABEL in it. */
3091 has_label_p (basic_block bb, tree label)
3093 block_stmt_iterator bsi;
3095 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3097 tree stmt = bsi_stmt (bsi);
3099 if (TREE_CODE (stmt) != LABEL_EXPR)
3101 if (LABEL_EXPR_LABEL (stmt) == label)
3108 /* Callback for walk_tree, check that all elements with address taken are
3109 properly noticed as such. The DATA is an int* that is 1 if TP was seen
3110 inside a PHI node. */
3113 verify_expr (tree *tp, int *walk_subtrees, void *data ATTRIBUTE_UNUSED)
3116 bool in_phi = (data != NULL);
3121 /* Check operand N for being valid GIMPLE and give error MSG if not. */
3122 #define CHECK_OP(N, MSG) \
3123 do { if (!is_gimple_val (TREE_OPERAND (t, N))) \
3124 { error (MSG); return TREE_OPERAND (t, N); }} while (0)
3126 switch (TREE_CODE (t))
3129 if (SSA_NAME_IN_FREE_LIST (t))
3131 error ("SSA name in freelist but still referenced");
3137 x = fold (ASSERT_EXPR_COND (t));
3138 if (x == boolean_false_node)
3140 error ("ASSERT_EXPR with an always-false condition");
3146 x = TREE_OPERAND (t, 0);
3147 if (TREE_CODE (x) == BIT_FIELD_REF
3148 && is_gimple_reg (TREE_OPERAND (x, 0)))
3150 error ("GIMPLE register modified with BIT_FIELD_REF");
3159 bool old_side_effects;
3162 bool new_side_effects;
3164 /* ??? tree-ssa-alias.c may have overlooked dead PHI nodes, missing
3165 dead PHIs that take the address of something. But if the PHI
3166 result is dead, the fact that it takes the address of anything
3167 is irrelevant. Because we can not tell from here if a PHI result
3168 is dead, we just skip this check for PHIs altogether. This means
3169 we may be missing "valid" checks, but what can you do?
3170 This was PR19217. */
3174 old_invariant = TREE_INVARIANT (t);
3175 old_constant = TREE_CONSTANT (t);
3176 old_side_effects = TREE_SIDE_EFFECTS (t);
3178 recompute_tree_invarant_for_addr_expr (t);
3179 new_invariant = TREE_INVARIANT (t);
3180 new_side_effects = TREE_SIDE_EFFECTS (t);
3181 new_constant = TREE_CONSTANT (t);
3183 if (old_invariant != new_invariant)
3185 error ("invariant not recomputed when ADDR_EXPR changed");
3189 if (old_constant != new_constant)
3191 error ("constant not recomputed when ADDR_EXPR changed");
3194 if (old_side_effects != new_side_effects)
3196 error ("side effects not recomputed when ADDR_EXPR changed");
3200 /* Skip any references (they will be checked when we recurse down the
3201 tree) and ensure that any variable used as a prefix is marked
3203 for (x = TREE_OPERAND (t, 0);
3204 handled_component_p (x);
3205 x = TREE_OPERAND (x, 0))
3208 if (TREE_CODE (x) != VAR_DECL && TREE_CODE (x) != PARM_DECL)
3210 if (!TREE_ADDRESSABLE (x))
3212 error ("address taken, but ADDRESSABLE bit not set");
3219 x = COND_EXPR_COND (t);
3220 if (TREE_CODE (TREE_TYPE (x)) != BOOLEAN_TYPE)
3222 error ("non-boolean used in condition");
3225 if (!is_gimple_condexpr (x))
3227 error ("invalid conditional operand");
3234 case FIX_TRUNC_EXPR:
3236 case FIX_FLOOR_EXPR:
3237 case FIX_ROUND_EXPR:
3242 case NON_LVALUE_EXPR:
3243 case TRUTH_NOT_EXPR:
3244 CHECK_OP (0, "invalid operand to unary operator");
3251 case ARRAY_RANGE_REF:
3253 case VIEW_CONVERT_EXPR:
3254 /* We have a nest of references. Verify that each of the operands
3255 that determine where to reference is either a constant or a variable,
3256 verify that the base is valid, and then show we've already checked
3258 while (handled_component_p (t))
3260 if (TREE_CODE (t) == COMPONENT_REF && TREE_OPERAND (t, 2))
3261 CHECK_OP (2, "invalid COMPONENT_REF offset operator");
3262 else if (TREE_CODE (t) == ARRAY_REF
3263 || TREE_CODE (t) == ARRAY_RANGE_REF)
3265 CHECK_OP (1, "invalid array index");
3266 if (TREE_OPERAND (t, 2))
3267 CHECK_OP (2, "invalid array lower bound");
3268 if (TREE_OPERAND (t, 3))
3269 CHECK_OP (3, "invalid array stride");
3271 else if (TREE_CODE (t) == BIT_FIELD_REF)
3273 CHECK_OP (1, "invalid operand to BIT_FIELD_REF");
3274 CHECK_OP (2, "invalid operand to BIT_FIELD_REF");
3277 t = TREE_OPERAND (t, 0);
3280 if (!CONSTANT_CLASS_P (t) && !is_gimple_lvalue (t))
3282 error ("invalid reference prefix");
3294 case UNORDERED_EXPR:
3305 case TRUNC_DIV_EXPR:
3307 case FLOOR_DIV_EXPR:
3308 case ROUND_DIV_EXPR:
3309 case TRUNC_MOD_EXPR:
3311 case FLOOR_MOD_EXPR:
3312 case ROUND_MOD_EXPR:
3314 case EXACT_DIV_EXPR:
3324 CHECK_OP (0, "invalid operand to binary operator");
3325 CHECK_OP (1, "invalid operand to binary operator");
3337 /* Verify STMT, return true if STMT is not in GIMPLE form.
3338 TODO: Implement type checking. */
3341 verify_stmt (tree stmt, bool last_in_block)
3345 if (!is_gimple_stmt (stmt))
3347 error ("is not a valid GIMPLE statement");
3351 addr = walk_tree (&stmt, verify_expr, NULL, NULL);
3354 debug_generic_stmt (addr);
3358 /* If the statement is marked as part of an EH region, then it is
3359 expected that the statement could throw. Verify that when we
3360 have optimizations that simplify statements such that we prove
3361 that they cannot throw, that we update other data structures
3363 if (lookup_stmt_eh_region (stmt) >= 0)
3365 if (!tree_could_throw_p (stmt))
3367 error ("statement marked for throw, but doesn%'t");
3370 if (!last_in_block && tree_can_throw_internal (stmt))
3372 error ("statement marked for throw in middle of block");
3380 debug_generic_stmt (stmt);
3385 /* Return true when the T can be shared. */
3388 tree_node_can_be_shared (tree t)
3390 if (IS_TYPE_OR_DECL_P (t)
3391 /* We check for constants explicitly since they are not considered
3392 gimple invariants if they overflowed. */
3393 || CONSTANT_CLASS_P (t)
3394 || is_gimple_min_invariant (t)
3395 || TREE_CODE (t) == SSA_NAME
3396 || t == error_mark_node)
3399 if (TREE_CODE (t) == CASE_LABEL_EXPR)
3402 while (((TREE_CODE (t) == ARRAY_REF || TREE_CODE (t) == ARRAY_RANGE_REF)
3403 /* We check for constants explicitly since they are not considered
3404 gimple invariants if they overflowed. */
3405 && (CONSTANT_CLASS_P (TREE_OPERAND (t, 1))
3406 || is_gimple_min_invariant (TREE_OPERAND (t, 1))))
3407 || (TREE_CODE (t) == COMPONENT_REF
3408 || TREE_CODE (t) == REALPART_EXPR
3409 || TREE_CODE (t) == IMAGPART_EXPR))
3410 t = TREE_OPERAND (t, 0);
3419 /* Called via walk_trees. Verify tree sharing. */
3422 verify_node_sharing (tree * tp, int *walk_subtrees, void *data)
3424 htab_t htab = (htab_t) data;
3427 if (tree_node_can_be_shared (*tp))
3429 *walk_subtrees = false;
3433 slot = htab_find_slot (htab, *tp, INSERT);
3442 /* Verify the GIMPLE statement chain. */
3448 block_stmt_iterator bsi;
3453 timevar_push (TV_TREE_STMT_VERIFY);
3454 htab = htab_create (37, htab_hash_pointer, htab_eq_pointer, NULL);
3461 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
3463 int phi_num_args = PHI_NUM_ARGS (phi);
3465 if (bb_for_stmt (phi) != bb)
3467 error ("bb_for_stmt (phi) is set to a wrong basic block");
3471 for (i = 0; i < phi_num_args; i++)
3473 tree t = PHI_ARG_DEF (phi, i);
3476 /* Addressable variables do have SSA_NAMEs but they
3477 are not considered gimple values. */
3478 if (TREE_CODE (t) != SSA_NAME
3479 && TREE_CODE (t) != FUNCTION_DECL
3480 && !is_gimple_val (t))
3482 error ("PHI def is not a GIMPLE value");
3483 debug_generic_stmt (phi);
3484 debug_generic_stmt (t);
3488 addr = walk_tree (&t, verify_expr, (void *) 1, NULL);
3491 debug_generic_stmt (addr);
3495 addr = walk_tree (&t, verify_node_sharing, htab, NULL);
3498 error ("incorrect sharing of tree nodes");
3499 debug_generic_stmt (phi);
3500 debug_generic_stmt (addr);
3506 for (bsi = bsi_start (bb); !bsi_end_p (bsi); )
3508 tree stmt = bsi_stmt (bsi);
3510 if (bb_for_stmt (stmt) != bb)
3512 error ("bb_for_stmt (stmt) is set to a wrong basic block");
3517 err |= verify_stmt (stmt, bsi_end_p (bsi));
3518 addr = walk_tree (&stmt, verify_node_sharing, htab, NULL);
3521 error ("incorrect sharing of tree nodes");
3522 debug_generic_stmt (stmt);
3523 debug_generic_stmt (addr);
3530 internal_error ("verify_stmts failed");
3533 timevar_pop (TV_TREE_STMT_VERIFY);
3537 /* Verifies that the flow information is OK. */
3540 tree_verify_flow_info (void)
3544 block_stmt_iterator bsi;
3549 if (ENTRY_BLOCK_PTR->stmt_list)
3551 error ("ENTRY_BLOCK has a statement list associated with it");
3555 if (EXIT_BLOCK_PTR->stmt_list)
3557 error ("EXIT_BLOCK has a statement list associated with it");
3561 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
3562 if (e->flags & EDGE_FALLTHRU)
3564 error ("fallthru to exit from bb %d", e->src->index);
3570 bool found_ctrl_stmt = false;
3574 /* Skip labels on the start of basic block. */
3575 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3577 tree prev_stmt = stmt;
3579 stmt = bsi_stmt (bsi);
3581 if (TREE_CODE (stmt) != LABEL_EXPR)
3584 if (prev_stmt && DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)))
3586 error ("nonlocal label %s is not first "
3587 "in a sequence of labels in bb %d",
3588 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt))),
3593 if (label_to_block (LABEL_EXPR_LABEL (stmt)) != bb)
3595 error ("label %s to block does not match in bb %d",
3596 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt))),
3601 if (decl_function_context (LABEL_EXPR_LABEL (stmt))
3602 != current_function_decl)
3604 error ("label %s has incorrect context in bb %d",
3605 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt))),
3611 /* Verify that body of basic block BB is free of control flow. */
3612 for (; !bsi_end_p (bsi); bsi_next (&bsi))
3614 tree stmt = bsi_stmt (bsi);
3616 if (found_ctrl_stmt)
3618 error ("control flow in the middle of basic block %d",
3623 if (stmt_ends_bb_p (stmt))
3624 found_ctrl_stmt = true;
3626 if (TREE_CODE (stmt) == LABEL_EXPR)
3628 error ("label %s in the middle of basic block %d",
3629 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt))),
3634 bsi = bsi_last (bb);
3635 if (bsi_end_p (bsi))
3638 stmt = bsi_stmt (bsi);
3640 err |= verify_eh_edges (stmt);
3642 if (is_ctrl_stmt (stmt))
3644 FOR_EACH_EDGE (e, ei, bb->succs)
3645 if (e->flags & EDGE_FALLTHRU)
3647 error ("fallthru edge after a control statement in bb %d",
3653 switch (TREE_CODE (stmt))
3659 if (TREE_CODE (COND_EXPR_THEN (stmt)) != GOTO_EXPR
3660 || TREE_CODE (COND_EXPR_ELSE (stmt)) != GOTO_EXPR)
3662 error ("structured COND_EXPR at the end of bb %d", bb->index);
3666 extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
3668 if (!true_edge || !false_edge
3669 || !(true_edge->flags & EDGE_TRUE_VALUE)
3670 || !(false_edge->flags & EDGE_FALSE_VALUE)
3671 || (true_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL))
3672 || (false_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL))
3673 || EDGE_COUNT (bb->succs) >= 3)
3675 error ("wrong outgoing edge flags at end of bb %d",
3680 if (!has_label_p (true_edge->dest,
3681 GOTO_DESTINATION (COND_EXPR_THEN (stmt))))
3683 error ("%<then%> label does not match edge at end of bb %d",
3688 if (!has_label_p (false_edge->dest,
3689 GOTO_DESTINATION (COND_EXPR_ELSE (stmt))))
3691 error ("%<else%> label does not match edge at end of bb %d",
3699 if (simple_goto_p (stmt))
3701 error ("explicit goto at end of bb %d", bb->index);
3706 /* FIXME. We should double check that the labels in the
3707 destination blocks have their address taken. */
3708 FOR_EACH_EDGE (e, ei, bb->succs)
3709 if ((e->flags & (EDGE_FALLTHRU | EDGE_TRUE_VALUE
3710 | EDGE_FALSE_VALUE))
3711 || !(e->flags & EDGE_ABNORMAL))
3713 error ("wrong outgoing edge flags at end of bb %d",
3721 if (!single_succ_p (bb)
3722 || (single_succ_edge (bb)->flags
3723 & (EDGE_FALLTHRU | EDGE_ABNORMAL
3724 | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
3726 error ("wrong outgoing edge flags at end of bb %d", bb->index);
3729 if (single_succ (bb) != EXIT_BLOCK_PTR)
3731 error ("return edge does not point to exit in bb %d",
3744 vec = SWITCH_LABELS (stmt);
3745 n = TREE_VEC_LENGTH (vec);
3747 /* Mark all the destination basic blocks. */
3748 for (i = 0; i < n; ++i)
3750 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
3751 basic_block label_bb = label_to_block (lab);
3753 gcc_assert (!label_bb->aux || label_bb->aux == (void *)1);
3754 label_bb->aux = (void *)1;
3757 /* Verify that the case labels are sorted. */
3758 prev = TREE_VEC_ELT (vec, 0);
3759 for (i = 1; i < n - 1; ++i)
3761 tree c = TREE_VEC_ELT (vec, i);
3764 error ("found default case not at end of case vector");
3768 if (! tree_int_cst_lt (CASE_LOW (prev), CASE_LOW (c)))
3770 error ("case labels not sorted:");
3771 print_generic_expr (stderr, prev, 0);
3772 fprintf (stderr," is greater than ");
3773 print_generic_expr (stderr, c, 0);
3774 fprintf (stderr," but comes before it.\n");
3779 if (CASE_LOW (TREE_VEC_ELT (vec, n - 1)))
3781 error ("no default case found at end of case vector");
3785 FOR_EACH_EDGE (e, ei, bb->succs)
3789 error ("extra outgoing edge %d->%d",
3790 bb->index, e->dest->index);
3793 e->dest->aux = (void *)2;
3794 if ((e->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL
3795 | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
3797 error ("wrong outgoing edge flags at end of bb %d",
3803 /* Check that we have all of them. */
3804 for (i = 0; i < n; ++i)
3806 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
3807 basic_block label_bb = label_to_block (lab);
3809 if (label_bb->aux != (void *)2)
3811 error ("missing edge %i->%i",
3812 bb->index, label_bb->index);
3817 FOR_EACH_EDGE (e, ei, bb->succs)
3818 e->dest->aux = (void *)0;
3825 if (dom_computed[CDI_DOMINATORS] >= DOM_NO_FAST_QUERY)
3826 verify_dominators (CDI_DOMINATORS);
3832 /* Updates phi nodes after creating a forwarder block joined
3833 by edge FALLTHRU. */
3836 tree_make_forwarder_block (edge fallthru)
3840 basic_block dummy, bb;
3841 tree phi, new_phi, var;
3843 dummy = fallthru->src;
3844 bb = fallthru->dest;
3846 if (single_pred_p (bb))
3849 /* If we redirected a branch we must create new phi nodes at the
3851 for (phi = phi_nodes (dummy); phi; phi = PHI_CHAIN (phi))
3853 var = PHI_RESULT (phi);
3854 new_phi = create_phi_node (var, bb);
3855 SSA_NAME_DEF_STMT (var) = new_phi;
3856 SET_PHI_RESULT (phi, make_ssa_name (SSA_NAME_VAR (var), phi));
3857 add_phi_arg (new_phi, PHI_RESULT (phi), fallthru);
3860 /* Ensure that the PHI node chain is in the same order. */
3861 set_phi_nodes (bb, phi_reverse (phi_nodes (bb)));
3863 /* Add the arguments we have stored on edges. */
3864 FOR_EACH_EDGE (e, ei, bb->preds)
3869 flush_pending_stmts (e);
3874 /* Return a non-special label in the head of basic block BLOCK.
3875 Create one if it doesn't exist. */
3878 tree_block_label (basic_block bb)
3880 block_stmt_iterator i, s = bsi_start (bb);
3884 for (i = s; !bsi_end_p (i); first = false, bsi_next (&i))
3886 stmt = bsi_stmt (i);
3887 if (TREE_CODE (stmt) != LABEL_EXPR)
3889 label = LABEL_EXPR_LABEL (stmt);
3890 if (!DECL_NONLOCAL (label))
3893 bsi_move_before (&i, &s);
3898 label = create_artificial_label ();
3899 stmt = build1 (LABEL_EXPR, void_type_node, label);
3900 bsi_insert_before (&s, stmt, BSI_NEW_STMT);
3905 /* Attempt to perform edge redirection by replacing a possibly complex
3906 jump instruction by a goto or by removing the jump completely.
3907 This can apply only if all edges now point to the same block. The
3908 parameters and return values are equivalent to
3909 redirect_edge_and_branch. */
3912 tree_try_redirect_by_replacing_jump (edge e, basic_block target)
3914 basic_block src = e->src;
3915 block_stmt_iterator b;
3918 /* We can replace or remove a complex jump only when we have exactly
3920 if (EDGE_COUNT (src->succs) != 2
3921 /* Verify that all targets will be TARGET. Specifically, the
3922 edge that is not E must also go to TARGET. */
3923 || EDGE_SUCC (src, EDGE_SUCC (src, 0) == e)->dest != target)
3929 stmt = bsi_stmt (b);
3931 if (TREE_CODE (stmt) == COND_EXPR
3932 || TREE_CODE (stmt) == SWITCH_EXPR)
3935 e = ssa_redirect_edge (e, target);
3936 e->flags = EDGE_FALLTHRU;
3944 /* Redirect E to DEST. Return NULL on failure. Otherwise, return the
3945 edge representing the redirected branch. */
3948 tree_redirect_edge_and_branch (edge e, basic_block dest)
3950 basic_block bb = e->src;
3951 block_stmt_iterator bsi;
3955 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
3958 if (e->src != ENTRY_BLOCK_PTR
3959 && (ret = tree_try_redirect_by_replacing_jump (e, dest)))
3962 if (e->dest == dest)
3965 label = tree_block_label (dest);
3967 bsi = bsi_last (bb);
3968 stmt = bsi_end_p (bsi) ? NULL : bsi_stmt (bsi);
3970 switch (stmt ? TREE_CODE (stmt) : ERROR_MARK)
3973 stmt = (e->flags & EDGE_TRUE_VALUE
3974 ? COND_EXPR_THEN (stmt)
3975 : COND_EXPR_ELSE (stmt));
3976 GOTO_DESTINATION (stmt) = label;
3980 /* No non-abnormal edges should lead from a non-simple goto, and
3981 simple ones should be represented implicitly. */
3986 tree cases = get_cases_for_edge (e, stmt);
3988 /* If we have a list of cases associated with E, then use it
3989 as it's a lot faster than walking the entire case vector. */
3992 edge e2 = find_edge (e->src, dest);
3999 CASE_LABEL (cases) = label;
4000 cases = TREE_CHAIN (cases);
4003 /* If there was already an edge in the CFG, then we need
4004 to move all the cases associated with E to E2. */
4007 tree cases2 = get_cases_for_edge (e2, stmt);
4009 TREE_CHAIN (last) = TREE_CHAIN (cases2);
4010 TREE_CHAIN (cases2) = first;
4015 tree vec = SWITCH_LABELS (stmt);
4016 size_t i, n = TREE_VEC_LENGTH (vec);
4018 for (i = 0; i < n; i++)
4020 tree elt = TREE_VEC_ELT (vec, i);
4022 if (label_to_block (CASE_LABEL (elt)) == e->dest)
4023 CASE_LABEL (elt) = label;
4032 e->flags |= EDGE_FALLTHRU;
4036 /* Otherwise it must be a fallthru edge, and we don't need to
4037 do anything besides redirecting it. */
4038 gcc_assert (e->flags & EDGE_FALLTHRU);
4042 /* Update/insert PHI nodes as necessary. */
4044 /* Now update the edges in the CFG. */
4045 e = ssa_redirect_edge (e, dest);
4051 /* Simple wrapper, as we can always redirect fallthru edges. */
4054 tree_redirect_edge_and_branch_force (edge e, basic_block dest)
4056 e = tree_redirect_edge_and_branch (e, dest);
4063 /* Splits basic block BB after statement STMT (but at least after the
4064 labels). If STMT is NULL, BB is split just after the labels. */
4067 tree_split_block (basic_block bb, void *stmt)
4069 block_stmt_iterator bsi, bsi_tgt;
4075 new_bb = create_empty_bb (bb);
4077 /* Redirect the outgoing edges. */
4078 new_bb->succs = bb->succs;
4080 FOR_EACH_EDGE (e, ei, new_bb->succs)
4083 if (stmt && TREE_CODE ((tree) stmt) == LABEL_EXPR)
4086 /* Move everything from BSI to the new basic block. */
4087 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4089 act = bsi_stmt (bsi);
4090 if (TREE_CODE (act) == LABEL_EXPR)
4103 bsi_tgt = bsi_start (new_bb);
4104 while (!bsi_end_p (bsi))
4106 act = bsi_stmt (bsi);
4108 bsi_insert_after (&bsi_tgt, act, BSI_NEW_STMT);
4115 /* Moves basic block BB after block AFTER. */
4118 tree_move_block_after (basic_block bb, basic_block after)
4120 if (bb->prev_bb == after)
4124 link_block (bb, after);
4130 /* Return true if basic_block can be duplicated. */
4133 tree_can_duplicate_bb_p (basic_block bb ATTRIBUTE_UNUSED)
4139 /* Create a duplicate of the basic block BB. NOTE: This does not
4140 preserve SSA form. */
4143 tree_duplicate_bb (basic_block bb)
4146 block_stmt_iterator bsi, bsi_tgt;
4149 new_bb = create_empty_bb (EXIT_BLOCK_PTR->prev_bb);
4151 /* Copy the PHI nodes. We ignore PHI node arguments here because
4152 the incoming edges have not been setup yet. */
4153 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
4155 tree copy = create_phi_node (PHI_RESULT (phi), new_bb);
4156 create_new_def_for (PHI_RESULT (copy), copy, PHI_RESULT_PTR (copy));
4159 /* Keep the chain of PHI nodes in the same order so that they can be
4160 updated by ssa_redirect_edge. */
4161 set_phi_nodes (new_bb, phi_reverse (phi_nodes (new_bb)));
4163 bsi_tgt = bsi_start (new_bb);
4164 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4166 def_operand_p def_p;
4167 ssa_op_iter op_iter;
4171 stmt = bsi_stmt (bsi);
4172 if (TREE_CODE (stmt) == LABEL_EXPR)
4175 /* Create a new copy of STMT and duplicate STMT's virtual
4177 copy = unshare_expr (stmt);
4178 bsi_insert_after (&bsi_tgt, copy, BSI_NEW_STMT);
4179 copy_virtual_operands (copy, stmt);
4180 region = lookup_stmt_eh_region (stmt);
4182 add_stmt_to_eh_region (copy, region);
4184 /* Create new names for all the definitions created by COPY and
4185 add replacement mappings for each new name. */
4186 FOR_EACH_SSA_DEF_OPERAND (def_p, copy, op_iter, SSA_OP_ALL_DEFS)
4187 create_new_def_for (DEF_FROM_PTR (def_p), copy, def_p);
4194 /* Basic block BB_COPY was created by code duplication. Add phi node
4195 arguments for edges going out of BB_COPY. The blocks that were
4196 duplicated have BB_DUPLICATED set. */
4199 add_phi_args_after_copy_bb (basic_block bb_copy)
4201 basic_block bb, dest;
4204 tree phi, phi_copy, phi_next, def;
4206 bb = get_bb_original (bb_copy);
4208 FOR_EACH_EDGE (e_copy, ei, bb_copy->succs)
4210 if (!phi_nodes (e_copy->dest))
4213 if (e_copy->dest->flags & BB_DUPLICATED)
4214 dest = get_bb_original (e_copy->dest);
4216 dest = e_copy->dest;
4218 e = find_edge (bb, dest);
4221 /* During loop unrolling the target of the latch edge is copied.
4222 In this case we are not looking for edge to dest, but to
4223 duplicated block whose original was dest. */
4224 FOR_EACH_EDGE (e, ei, bb->succs)
4225 if ((e->dest->flags & BB_DUPLICATED)
4226 && get_bb_original (e->dest) == dest)
4229 gcc_assert (e != NULL);
4232 for (phi = phi_nodes (e->dest), phi_copy = phi_nodes (e_copy->dest);
4234 phi = phi_next, phi_copy = PHI_CHAIN (phi_copy))
4236 phi_next = PHI_CHAIN (phi);
4237 def = PHI_ARG_DEF_FROM_EDGE (phi, e);
4238 add_phi_arg (phi_copy, def, e_copy);
4243 /* Blocks in REGION_COPY array of length N_REGION were created by
4244 duplication of basic blocks. Add phi node arguments for edges
4245 going from these blocks. */
4248 add_phi_args_after_copy (basic_block *region_copy, unsigned n_region)
4252 for (i = 0; i < n_region; i++)
4253 region_copy[i]->flags |= BB_DUPLICATED;
4255 for (i = 0; i < n_region; i++)
4256 add_phi_args_after_copy_bb (region_copy[i]);
4258 for (i = 0; i < n_region; i++)
4259 region_copy[i]->flags &= ~BB_DUPLICATED;
4262 /* Duplicates a REGION (set of N_REGION basic blocks) with just a single
4263 important exit edge EXIT. By important we mean that no SSA name defined
4264 inside region is live over the other exit edges of the region. All entry
4265 edges to the region must go to ENTRY->dest. The edge ENTRY is redirected
4266 to the duplicate of the region. SSA form, dominance and loop information
4267 is updated. The new basic blocks are stored to REGION_COPY in the same
4268 order as they had in REGION, provided that REGION_COPY is not NULL.
4269 The function returns false if it is unable to copy the region,
4273 tree_duplicate_sese_region (edge entry, edge exit,
4274 basic_block *region, unsigned n_region,
4275 basic_block *region_copy)
4278 bool free_region_copy = false, copying_header = false;
4279 struct loop *loop = entry->dest->loop_father;
4283 int total_freq = 0, entry_freq = 0;
4284 gcov_type total_count = 0, entry_count = 0;
4286 if (!can_copy_bbs_p (region, n_region))
4289 /* Some sanity checking. Note that we do not check for all possible
4290 missuses of the functions. I.e. if you ask to copy something weird,
4291 it will work, but the state of structures probably will not be
4293 for (i = 0; i < n_region; i++)
4295 /* We do not handle subloops, i.e. all the blocks must belong to the
4297 if (region[i]->loop_father != loop)
4300 if (region[i] != entry->dest
4301 && region[i] == loop->header)
4307 /* In case the function is used for loop header copying (which is the primary
4308 use), ensure that EXIT and its copy will be new latch and entry edges. */
4309 if (loop->header == entry->dest)
4311 copying_header = true;
4312 loop->copy = loop->outer;
4314 if (!dominated_by_p (CDI_DOMINATORS, loop->latch, exit->src))
4317 for (i = 0; i < n_region; i++)
4318 if (region[i] != exit->src
4319 && dominated_by_p (CDI_DOMINATORS, region[i], exit->src))
4325 region_copy = xmalloc (sizeof (basic_block) * n_region);
4326 free_region_copy = true;
4329 gcc_assert (!need_ssa_update_p ());
4331 /* Record blocks outside the region that are dominated by something
4333 doms = xmalloc (sizeof (basic_block) * n_basic_blocks);
4334 initialize_original_copy_tables ();
4336 n_doms = get_dominated_by_region (CDI_DOMINATORS, region, n_region, doms);
4338 if (entry->dest->count)
4340 total_count = entry->dest->count;
4341 entry_count = entry->count;
4342 /* Fix up corner cases, to avoid division by zero or creation of negative
4344 if (entry_count > total_count)
4345 entry_count = total_count;
4349 total_freq = entry->dest->frequency;
4350 entry_freq = EDGE_FREQUENCY (entry);
4351 /* Fix up corner cases, to avoid division by zero or creation of negative
4353 if (total_freq == 0)
4355 else if (entry_freq > total_freq)
4356 entry_freq = total_freq;
4359 copy_bbs (region, n_region, region_copy, &exit, 1, &exit_copy, loop,
4360 split_edge_bb_loc (entry));
4363 scale_bbs_frequencies_gcov_type (region, n_region,
4364 total_count - entry_count,
4366 scale_bbs_frequencies_gcov_type (region_copy, n_region, entry_count,
4371 scale_bbs_frequencies_int (region, n_region, total_freq - entry_freq,
4373 scale_bbs_frequencies_int (region_copy, n_region, entry_freq, total_freq);
4378 loop->header = exit->dest;
4379 loop->latch = exit->src;
4382 /* Redirect the entry and add the phi node arguments. */
4383 redirected = redirect_edge_and_branch (entry, get_bb_copy (entry->dest));
4384 gcc_assert (redirected != NULL);
4385 flush_pending_stmts (entry);
4387 /* Concerning updating of dominators: We must recount dominators
4388 for entry block and its copy. Anything that is outside of the
4389 region, but was dominated by something inside needs recounting as
4391 set_immediate_dominator (CDI_DOMINATORS, entry->dest, entry->src);
4392 doms[n_doms++] = get_bb_original (entry->dest);
4393 iterate_fix_dominators (CDI_DOMINATORS, doms, n_doms);
4396 /* Add the other PHI node arguments. */
4397 add_phi_args_after_copy (region_copy, n_region);
4399 /* Update the SSA web. */
4400 update_ssa (TODO_update_ssa);
4402 if (free_region_copy)
4405 free_original_copy_tables ();
4410 /* Dump FUNCTION_DECL FN to file FILE using FLAGS (see TDF_* in tree.h) */
4413 dump_function_to_file (tree fn, FILE *file, int flags)
4415 tree arg, vars, var;
4416 bool ignore_topmost_bind = false, any_var = false;
4420 fprintf (file, "%s (", lang_hooks.decl_printable_name (fn, 2));
4422 arg = DECL_ARGUMENTS (fn);
4425 print_generic_expr (file, arg, dump_flags);
4426 if (TREE_CHAIN (arg))
4427 fprintf (file, ", ");
4428 arg = TREE_CHAIN (arg);
4430 fprintf (file, ")\n");
4432 if (flags & TDF_DETAILS)
4433 dump_eh_tree (file, DECL_STRUCT_FUNCTION (fn));
4434 if (flags & TDF_RAW)
4436 dump_node (fn, TDF_SLIM | flags, file);
4440 /* When GIMPLE is lowered, the variables are no longer available in
4441 BIND_EXPRs, so display them separately. */
4442 if (cfun && cfun->decl == fn && cfun->unexpanded_var_list)
4444 ignore_topmost_bind = true;
4446 fprintf (file, "{\n");
4447 for (vars = cfun->unexpanded_var_list; vars; vars = TREE_CHAIN (vars))
4449 var = TREE_VALUE (vars);
4451 print_generic_decl (file, var, flags);
4452 fprintf (file, "\n");
4458 if (cfun && cfun->decl == fn && cfun->cfg && basic_block_info)
4460 /* Make a CFG based dump. */
4461 check_bb_profile (ENTRY_BLOCK_PTR, file);
4462 if (!ignore_topmost_bind)
4463 fprintf (file, "{\n");
4465 if (any_var && n_basic_blocks)
4466 fprintf (file, "\n");
4469 dump_generic_bb (file, bb, 2, flags);
4471 fprintf (file, "}\n");
4472 check_bb_profile (EXIT_BLOCK_PTR, file);
4478 /* Make a tree based dump. */
4479 chain = DECL_SAVED_TREE (fn);
4481 if (TREE_CODE (chain) == BIND_EXPR)
4483 if (ignore_topmost_bind)
4485 chain = BIND_EXPR_BODY (chain);
4493 if (!ignore_topmost_bind)
4494 fprintf (file, "{\n");
4499 fprintf (file, "\n");
4501 print_generic_stmt_indented (file, chain, flags, indent);
4502 if (ignore_topmost_bind)
4503 fprintf (file, "}\n");
4506 fprintf (file, "\n\n");
4510 /* Pretty print of the loops intermediate representation. */
4511 static void print_loop (FILE *, struct loop *, int);
4512 static void print_pred_bbs (FILE *, basic_block bb);
4513 static void print_succ_bbs (FILE *, basic_block bb);
4516 /* Print on FILE the indexes for the predecessors of basic_block BB. */
4519 print_pred_bbs (FILE *file, basic_block bb)
4524 FOR_EACH_EDGE (e, ei, bb->preds)
4525 fprintf (file, "bb_%d ", e->src->index);
4529 /* Print on FILE the indexes for the successors of basic_block BB. */
4532 print_succ_bbs (FILE *file, basic_block bb)
4537 FOR_EACH_EDGE (e, ei, bb->succs)
4538 fprintf (file, "bb_%d ", e->dest->index);
4542 /* Pretty print LOOP on FILE, indented INDENT spaces. */
4545 print_loop (FILE *file, struct loop *loop, int indent)
4553 s_indent = (char *) alloca ((size_t) indent + 1);
4554 memset ((void *) s_indent, ' ', (size_t) indent);
4555 s_indent[indent] = '\0';
4557 /* Print the loop's header. */
4558 fprintf (file, "%sloop_%d\n", s_indent, loop->num);
4560 /* Print the loop's body. */
4561 fprintf (file, "%s{\n", s_indent);
4563 if (bb->loop_father == loop)
4565 /* Print the basic_block's header. */
4566 fprintf (file, "%s bb_%d (preds = {", s_indent, bb->index);
4567 print_pred_bbs (file, bb);
4568 fprintf (file, "}, succs = {");
4569 print_succ_bbs (file, bb);
4570 fprintf (file, "})\n");
4572 /* Print the basic_block's body. */
4573 fprintf (file, "%s {\n", s_indent);
4574 tree_dump_bb (bb, file, indent + 4);
4575 fprintf (file, "%s }\n", s_indent);
4578 print_loop (file, loop->inner, indent + 2);
4579 fprintf (file, "%s}\n", s_indent);
4580 print_loop (file, loop->next, indent);
4584 /* Follow a CFG edge from the entry point of the program, and on entry
4585 of a loop, pretty print the loop structure on FILE. */
4588 print_loop_ir (FILE *file)
4592 bb = BASIC_BLOCK (0);
4593 if (bb && bb->loop_father)
4594 print_loop (file, bb->loop_father, 0);
4598 /* Debugging loops structure at tree level. */
4601 debug_loop_ir (void)
4603 print_loop_ir (stderr);
4607 /* Return true if BB ends with a call, possibly followed by some
4608 instructions that must stay with the call. Return false,
4612 tree_block_ends_with_call_p (basic_block bb)
4614 block_stmt_iterator bsi = bsi_last (bb);
4615 return get_call_expr_in (bsi_stmt (bsi)) != NULL;
4619 /* Return true if BB ends with a conditional branch. Return false,
4623 tree_block_ends_with_condjump_p (basic_block bb)
4625 tree stmt = last_stmt (bb);
4626 return (stmt && TREE_CODE (stmt) == COND_EXPR);
4630 /* Return true if we need to add fake edge to exit at statement T.
4631 Helper function for tree_flow_call_edges_add. */
4634 need_fake_edge_p (tree t)
4638 /* NORETURN and LONGJMP calls already have an edge to exit.
4639 CONST and PURE calls do not need one.
4640 We don't currently check for CONST and PURE here, although
4641 it would be a good idea, because those attributes are
4642 figured out from the RTL in mark_constant_function, and
4643 the counter incrementation code from -fprofile-arcs
4644 leads to different results from -fbranch-probabilities. */
4645 call = get_call_expr_in (t);
4647 && !(call_expr_flags (call) & ECF_NORETURN))
4650 if (TREE_CODE (t) == ASM_EXPR
4651 && (ASM_VOLATILE_P (t) || ASM_INPUT_P (t)))
4658 /* Add fake edges to the function exit for any non constant and non
4659 noreturn calls, volatile inline assembly in the bitmap of blocks
4660 specified by BLOCKS or to the whole CFG if BLOCKS is zero. Return
4661 the number of blocks that were split.
4663 The goal is to expose cases in which entering a basic block does
4664 not imply that all subsequent instructions must be executed. */
4667 tree_flow_call_edges_add (sbitmap blocks)
4670 int blocks_split = 0;
4671 int last_bb = last_basic_block;
4672 bool check_last_block = false;
4674 if (n_basic_blocks == 0)
4678 check_last_block = true;
4680 check_last_block = TEST_BIT (blocks, EXIT_BLOCK_PTR->prev_bb->index);
4682 /* In the last basic block, before epilogue generation, there will be
4683 a fallthru edge to EXIT. Special care is required if the last insn
4684 of the last basic block is a call because make_edge folds duplicate
4685 edges, which would result in the fallthru edge also being marked
4686 fake, which would result in the fallthru edge being removed by
4687 remove_fake_edges, which would result in an invalid CFG.
4689 Moreover, we can't elide the outgoing fake edge, since the block
4690 profiler needs to take this into account in order to solve the minimal
4691 spanning tree in the case that the call doesn't return.
4693 Handle this by adding a dummy instruction in a new last basic block. */
4694 if (check_last_block)
4696 basic_block bb = EXIT_BLOCK_PTR->prev_bb;
4697 block_stmt_iterator bsi = bsi_last (bb);
4699 if (!bsi_end_p (bsi))
4702 if (need_fake_edge_p (t))
4706 e = find_edge (bb, EXIT_BLOCK_PTR);
4709 bsi_insert_on_edge (e, build_empty_stmt ());
4710 bsi_commit_edge_inserts ();
4715 /* Now add fake edges to the function exit for any non constant
4716 calls since there is no way that we can determine if they will
4718 for (i = 0; i < last_bb; i++)
4720 basic_block bb = BASIC_BLOCK (i);
4721 block_stmt_iterator bsi;
4722 tree stmt, last_stmt;
4727 if (blocks && !TEST_BIT (blocks, i))
4730 bsi = bsi_last (bb);
4731 if (!bsi_end_p (bsi))
4733 last_stmt = bsi_stmt (bsi);
4736 stmt = bsi_stmt (bsi);
4737 if (need_fake_edge_p (stmt))
4740 /* The handling above of the final block before the
4741 epilogue should be enough to verify that there is
4742 no edge to the exit block in CFG already.
4743 Calling make_edge in such case would cause us to
4744 mark that edge as fake and remove it later. */
4745 #ifdef ENABLE_CHECKING
4746 if (stmt == last_stmt)
4748 e = find_edge (bb, EXIT_BLOCK_PTR);
4749 gcc_assert (e == NULL);
4753 /* Note that the following may create a new basic block
4754 and renumber the existing basic blocks. */
4755 if (stmt != last_stmt)
4757 e = split_block (bb, stmt);
4761 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
4765 while (!bsi_end_p (bsi));
4770 verify_flow_info ();
4772 return blocks_split;
4776 tree_purge_dead_eh_edges (basic_block bb)
4778 bool changed = false;
4781 tree stmt = last_stmt (bb);
4783 if (stmt && tree_can_throw_internal (stmt))
4786 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
4788 if (e->flags & EDGE_EH)
4797 /* Removal of dead EH edges might change dominators of not
4798 just immediate successors. E.g. when bb1 is changed so that
4799 it no longer can throw and bb1->bb3 and bb1->bb4 are dead
4800 eh edges purged by this function in:
4812 idom(bb5) must be recomputed. For now just free the dominance
4815 free_dominance_info (CDI_DOMINATORS);
4821 tree_purge_all_dead_eh_edges (bitmap blocks)
4823 bool changed = false;
4827 EXECUTE_IF_SET_IN_BITMAP (blocks, 0, i, bi)
4829 changed |= tree_purge_dead_eh_edges (BASIC_BLOCK (i));
4835 /* This function is called whenever a new edge is created or
4839 tree_execute_on_growing_pred (edge e)
4841 basic_block bb = e->dest;
4844 reserve_phi_args_for_new_edge (bb);
4847 /* This function is called immediately before edge E is removed from
4848 the edge vector E->dest->preds. */
4851 tree_execute_on_shrinking_pred (edge e)
4853 if (phi_nodes (e->dest))
4854 remove_phi_args (e);
4857 /*---------------------------------------------------------------------------
4858 Helper functions for Loop versioning
4859 ---------------------------------------------------------------------------*/
4861 /* Adjust phi nodes for 'first' basic block. 'second' basic block is a copy
4862 of 'first'. Both of them are dominated by 'new_head' basic block. When
4863 'new_head' was created by 'second's incoming edge it received phi arguments
4864 on the edge by split_edge(). Later, additional edge 'e' was created to
4865 connect 'new_head' and 'first'. Now this routine adds phi args on this
4866 additional edge 'e' that new_head to second edge received as part of edge
4871 tree_lv_adjust_loop_header_phi (basic_block first, basic_block second,
4872 basic_block new_head, edge e)
4875 edge e2 = find_edge (new_head, second);
4877 /* Because NEW_HEAD has been created by splitting SECOND's incoming
4878 edge, we should always have an edge from NEW_HEAD to SECOND. */
4879 gcc_assert (e2 != NULL);
4881 /* Browse all 'second' basic block phi nodes and add phi args to
4882 edge 'e' for 'first' head. PHI args are always in correct order. */
4884 for (phi2 = phi_nodes (second), phi1 = phi_nodes (first);
4886 phi2 = PHI_CHAIN (phi2), phi1 = PHI_CHAIN (phi1))
4888 tree def = PHI_ARG_DEF (phi2, e2->dest_idx);
4889 add_phi_arg (phi1, def, e);
4893 /* Adds a if else statement to COND_BB with condition COND_EXPR.
4894 SECOND_HEAD is the destination of the THEN and FIRST_HEAD is
4895 the destination of the ELSE part. */
4897 tree_lv_add_condition_to_bb (basic_block first_head, basic_block second_head,
4898 basic_block cond_bb, void *cond_e)
4900 block_stmt_iterator bsi;
4901 tree goto1 = NULL_TREE;
4902 tree goto2 = NULL_TREE;
4903 tree new_cond_expr = NULL_TREE;
4904 tree cond_expr = (tree) cond_e;
4907 /* Build new conditional expr */
4908 goto1 = build1 (GOTO_EXPR, void_type_node, tree_block_label (first_head));
4909 goto2 = build1 (GOTO_EXPR, void_type_node, tree_block_label (second_head));
4910 new_cond_expr = build3 (COND_EXPR, void_type_node, cond_expr, goto1, goto2);
4912 /* Add new cond in cond_bb. */
4913 bsi = bsi_start (cond_bb);
4914 bsi_insert_after (&bsi, new_cond_expr, BSI_NEW_STMT);
4915 /* Adjust edges appropriately to connect new head with first head
4916 as well as second head. */
4917 e0 = single_succ_edge (cond_bb);
4918 e0->flags &= ~EDGE_FALLTHRU;
4919 e0->flags |= EDGE_FALSE_VALUE;
4922 struct cfg_hooks tree_cfg_hooks = {
4924 tree_verify_flow_info,
4925 tree_dump_bb, /* dump_bb */
4926 create_bb, /* create_basic_block */
4927 tree_redirect_edge_and_branch,/* redirect_edge_and_branch */
4928 tree_redirect_edge_and_branch_force,/* redirect_edge_and_branch_force */
4929 remove_bb, /* delete_basic_block */
4930 tree_split_block, /* split_block */
4931 tree_move_block_after, /* move_block_after */
4932 tree_can_merge_blocks_p, /* can_merge_blocks_p */
4933 tree_merge_blocks, /* merge_blocks */
4934 tree_predict_edge, /* predict_edge */
4935 tree_predicted_by_p, /* predicted_by_p */
4936 tree_can_duplicate_bb_p, /* can_duplicate_block_p */
4937 tree_duplicate_bb, /* duplicate_block */
4938 tree_split_edge, /* split_edge */
4939 tree_make_forwarder_block, /* make_forward_block */
4940 NULL, /* tidy_fallthru_edge */
4941 tree_block_ends_with_call_p, /* block_ends_with_call_p */
4942 tree_block_ends_with_condjump_p, /* block_ends_with_condjump_p */
4943 tree_flow_call_edges_add, /* flow_call_edges_add */
4944 tree_execute_on_growing_pred, /* execute_on_growing_pred */
4945 tree_execute_on_shrinking_pred, /* execute_on_shrinking_pred */
4946 tree_duplicate_loop_to_header_edge, /* duplicate loop for trees */
4947 tree_lv_add_condition_to_bb, /* lv_add_condition_to_bb */
4948 tree_lv_adjust_loop_header_phi, /* lv_adjust_loop_header_phi*/
4949 extract_true_false_edges_from_block, /* extract_cond_bb_edges */
4950 flush_pending_stmts /* flush_pending_stmts */
4954 /* Split all critical edges. */
4957 split_critical_edges (void)
4963 /* split_edge can redirect edges out of SWITCH_EXPRs, which can get
4964 expensive. So we want to enable recording of edge to CASE_LABEL_EXPR
4965 mappings around the calls to split_edge. */
4966 start_recording_case_labels ();
4969 FOR_EACH_EDGE (e, ei, bb->succs)
4970 if (EDGE_CRITICAL_P (e) && !(e->flags & EDGE_ABNORMAL))
4975 end_recording_case_labels ();
4978 struct tree_opt_pass pass_split_crit_edges =
4980 "crited", /* name */
4982 split_critical_edges, /* execute */
4985 0, /* static_pass_number */
4986 TV_TREE_SPLIT_EDGES, /* tv_id */
4987 PROP_cfg, /* properties required */
4988 PROP_no_crit_edges, /* properties_provided */
4989 0, /* properties_destroyed */
4990 0, /* todo_flags_start */
4991 TODO_dump_func, /* todo_flags_finish */
4996 /* Return EXP if it is a valid GIMPLE rvalue, else gimplify it into
4997 a temporary, make sure and register it to be renamed if necessary,
4998 and finally return the temporary. Put the statements to compute
4999 EXP before the current statement in BSI. */
5002 gimplify_val (block_stmt_iterator *bsi, tree type, tree exp)
5004 tree t, new_stmt, orig_stmt;
5006 if (is_gimple_val (exp))
5009 t = make_rename_temp (type, NULL);
5010 new_stmt = build (MODIFY_EXPR, type, t, exp);
5012 orig_stmt = bsi_stmt (*bsi);
5013 SET_EXPR_LOCUS (new_stmt, EXPR_LOCUS (orig_stmt));
5014 TREE_BLOCK (new_stmt) = TREE_BLOCK (orig_stmt);
5016 bsi_insert_before (bsi, new_stmt, BSI_SAME_STMT);
5021 /* Build a ternary operation and gimplify it. Emit code before BSI.
5022 Return the gimple_val holding the result. */
5025 gimplify_build3 (block_stmt_iterator *bsi, enum tree_code code,
5026 tree type, tree a, tree b, tree c)
5030 ret = fold_build3 (code, type, a, b, c);
5033 return gimplify_val (bsi, type, ret);
5036 /* Build a binary operation and gimplify it. Emit code before BSI.
5037 Return the gimple_val holding the result. */
5040 gimplify_build2 (block_stmt_iterator *bsi, enum tree_code code,
5041 tree type, tree a, tree b)
5045 ret = fold_build2 (code, type, a, b);
5048 return gimplify_val (bsi, type, ret);
5051 /* Build a unary operation and gimplify it. Emit code before BSI.
5052 Return the gimple_val holding the result. */
5055 gimplify_build1 (block_stmt_iterator *bsi, enum tree_code code, tree type,
5060 ret = fold_build1 (code, type, a);
5063 return gimplify_val (bsi, type, ret);
5068 /* Emit return warnings. */
5071 execute_warn_function_return (void)
5073 #ifdef USE_MAPPED_LOCATION
5074 source_location location;
5082 /* If we have a path to EXIT, then we do return. */
5083 if (TREE_THIS_VOLATILE (cfun->decl)
5084 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) > 0)
5086 #ifdef USE_MAPPED_LOCATION
5087 location = UNKNOWN_LOCATION;
5091 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
5093 last = last_stmt (e->src);
5094 if (TREE_CODE (last) == RETURN_EXPR
5095 #ifdef USE_MAPPED_LOCATION
5096 && (location = EXPR_LOCATION (last)) != UNKNOWN_LOCATION)
5098 && (locus = EXPR_LOCUS (last)) != NULL)
5102 #ifdef USE_MAPPED_LOCATION
5103 if (location == UNKNOWN_LOCATION)
5104 location = cfun->function_end_locus;
5105 warning (0, "%H%<noreturn%> function does return", &location);
5108 locus = &cfun->function_end_locus;
5109 warning (0, "%H%<noreturn%> function does return", locus);
5113 /* If we see "return;" in some basic block, then we do reach the end
5114 without returning a value. */
5115 else if (warn_return_type
5116 && !TREE_NO_WARNING (cfun->decl)
5117 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) > 0
5118 && !VOID_TYPE_P (TREE_TYPE (TREE_TYPE (cfun->decl))))
5120 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
5122 tree last = last_stmt (e->src);
5123 if (TREE_CODE (last) == RETURN_EXPR
5124 && TREE_OPERAND (last, 0) == NULL)
5126 #ifdef USE_MAPPED_LOCATION
5127 location = EXPR_LOCATION (last);
5128 if (location == UNKNOWN_LOCATION)
5129 location = cfun->function_end_locus;
5130 warning (0, "%Hcontrol reaches end of non-void function", &location);
5132 locus = EXPR_LOCUS (last);
5134 locus = &cfun->function_end_locus;
5135 warning (0, "%Hcontrol reaches end of non-void function", locus);
5137 TREE_NO_WARNING (cfun->decl) = 1;
5145 /* Given a basic block B which ends with a conditional and has
5146 precisely two successors, determine which of the edges is taken if
5147 the conditional is true and which is taken if the conditional is
5148 false. Set TRUE_EDGE and FALSE_EDGE appropriately. */
5151 extract_true_false_edges_from_block (basic_block b,
5155 edge e = EDGE_SUCC (b, 0);
5157 if (e->flags & EDGE_TRUE_VALUE)
5160 *false_edge = EDGE_SUCC (b, 1);
5165 *true_edge = EDGE_SUCC (b, 1);
5169 struct tree_opt_pass pass_warn_function_return =
5173 execute_warn_function_return, /* execute */
5176 0, /* static_pass_number */
5178 PROP_cfg, /* properties_required */
5179 0, /* properties_provided */
5180 0, /* properties_destroyed */
5181 0, /* todo_flags_start */
5182 0, /* todo_flags_finish */
5186 /* Emit noreturn warnings. */
5189 execute_warn_function_noreturn (void)
5191 if (warn_missing_noreturn
5192 && !TREE_THIS_VOLATILE (cfun->decl)
5193 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) == 0
5194 && !lang_hooks.function.missing_noreturn_ok_p (cfun->decl))
5195 warning (OPT_Wmissing_noreturn, "%Jfunction might be possible candidate "
5196 "for attribute %<noreturn%>",
5200 struct tree_opt_pass pass_warn_function_noreturn =
5204 execute_warn_function_noreturn, /* execute */
5207 0, /* static_pass_number */
5209 PROP_cfg, /* properties_required */
5210 0, /* properties_provided */
5211 0, /* properties_destroyed */
5212 0, /* todo_flags_start */
5213 0, /* todo_flags_finish */