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)))
1988 basic_block new_bb = bb->prev_bb;
1989 block_stmt_iterator new_bsi = bsi_start (new_bb);
1992 bsi_insert_before (&new_bsi, stmt, BSI_NEW_STMT);
1996 /* Release SSA definitions if we are in SSA. Note that we
1997 may be called when not in SSA. For example,
1998 final_cleanup calls this function via
1999 cleanup_tree_cfg. */
2001 release_defs (stmt);
2006 /* Don't warn for removed gotos. Gotos are often removed due to
2007 jump threading, thus resulting in bogus warnings. Not great,
2008 since this way we lose warnings for gotos in the original
2009 program that are indeed unreachable. */
2010 if (TREE_CODE (stmt) != GOTO_EXPR && EXPR_HAS_LOCATION (stmt) && !loc)
2012 #ifdef USE_MAPPED_LOCATION
2013 if (EXPR_HAS_LOCATION (stmt))
2014 loc = EXPR_LOCATION (stmt);
2017 t = EXPR_LOCUS (stmt);
2018 if (t && LOCATION_LINE (*t) > 0)
2024 /* If requested, give a warning that the first statement in the
2025 block is unreachable. We walk statements backwards in the
2026 loop above, so the last statement we process is the first statement
2028 #ifdef USE_MAPPED_LOCATION
2029 if (loc > BUILTINS_LOCATION)
2030 warning (OPT_Wunreachable_code, "%Hwill never be executed", &loc);
2033 warning (OPT_Wunreachable_code, "%Hwill never be executed", loc);
2036 remove_phi_nodes_and_edges_for_unreachable_block (bb);
2040 /* Given a basic block BB ending with COND_EXPR or SWITCH_EXPR, and a
2041 predicate VAL, return the edge that will be taken out of the block.
2042 If VAL does not match a unique edge, NULL is returned. */
2045 find_taken_edge (basic_block bb, tree val)
2049 stmt = last_stmt (bb);
2052 gcc_assert (is_ctrl_stmt (stmt));
2055 if (! is_gimple_min_invariant (val))
2058 if (TREE_CODE (stmt) == COND_EXPR)
2059 return find_taken_edge_cond_expr (bb, val);
2061 if (TREE_CODE (stmt) == SWITCH_EXPR)
2062 return find_taken_edge_switch_expr (bb, val);
2064 if (computed_goto_p (stmt))
2065 return find_taken_edge_computed_goto (bb, TREE_OPERAND( val, 0));
2070 /* Given a constant value VAL and the entry block BB to a GOTO_EXPR
2071 statement, determine which of the outgoing edges will be taken out of the
2072 block. Return NULL if either edge may be taken. */
2075 find_taken_edge_computed_goto (basic_block bb, tree val)
2080 dest = label_to_block (val);
2083 e = find_edge (bb, dest);
2084 gcc_assert (e != NULL);
2090 /* Given a constant value VAL and the entry block BB to a COND_EXPR
2091 statement, determine which of the two edges will be taken out of the
2092 block. Return NULL if either edge may be taken. */
2095 find_taken_edge_cond_expr (basic_block bb, tree val)
2097 edge true_edge, false_edge;
2099 extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
2101 gcc_assert (TREE_CODE (val) == INTEGER_CST);
2102 return (zero_p (val) ? false_edge : true_edge);
2105 /* Given an INTEGER_CST VAL and the entry block BB to a SWITCH_EXPR
2106 statement, determine which edge will be taken out of the block. Return
2107 NULL if any edge may be taken. */
2110 find_taken_edge_switch_expr (basic_block bb, tree val)
2112 tree switch_expr, taken_case;
2113 basic_block dest_bb;
2116 switch_expr = last_stmt (bb);
2117 taken_case = find_case_label_for_value (switch_expr, val);
2118 dest_bb = label_to_block (CASE_LABEL (taken_case));
2120 e = find_edge (bb, dest_bb);
2126 /* Return the CASE_LABEL_EXPR that SWITCH_EXPR will take for VAL.
2127 We can make optimal use here of the fact that the case labels are
2128 sorted: We can do a binary search for a case matching VAL. */
2131 find_case_label_for_value (tree switch_expr, tree val)
2133 tree vec = SWITCH_LABELS (switch_expr);
2134 size_t low, high, n = TREE_VEC_LENGTH (vec);
2135 tree default_case = TREE_VEC_ELT (vec, n - 1);
2137 for (low = -1, high = n - 1; high - low > 1; )
2139 size_t i = (high + low) / 2;
2140 tree t = TREE_VEC_ELT (vec, i);
2143 /* Cache the result of comparing CASE_LOW and val. */
2144 cmp = tree_int_cst_compare (CASE_LOW (t), val);
2151 if (CASE_HIGH (t) == NULL)
2153 /* A singe-valued case label. */
2159 /* A case range. We can only handle integer ranges. */
2160 if (cmp <= 0 && tree_int_cst_compare (CASE_HIGH (t), val) >= 0)
2165 return default_case;
2171 /*---------------------------------------------------------------------------
2173 ---------------------------------------------------------------------------*/
2175 /* Dump tree-specific information of block BB to file OUTF. */
2178 tree_dump_bb (basic_block bb, FILE *outf, int indent)
2180 dump_generic_bb (outf, bb, indent, TDF_VOPS);
2184 /* Dump a basic block on stderr. */
2187 debug_tree_bb (basic_block bb)
2189 dump_bb (bb, stderr, 0);
2193 /* Dump basic block with index N on stderr. */
2196 debug_tree_bb_n (int n)
2198 debug_tree_bb (BASIC_BLOCK (n));
2199 return BASIC_BLOCK (n);
2203 /* Dump the CFG on stderr.
2205 FLAGS are the same used by the tree dumping functions
2206 (see TDF_* in tree.h). */
2209 debug_tree_cfg (int flags)
2211 dump_tree_cfg (stderr, flags);
2215 /* Dump the program showing basic block boundaries on the given FILE.
2217 FLAGS are the same used by the tree dumping functions (see TDF_* in
2221 dump_tree_cfg (FILE *file, int flags)
2223 if (flags & TDF_DETAILS)
2225 const char *funcname
2226 = lang_hooks.decl_printable_name (current_function_decl, 2);
2229 fprintf (file, ";; Function %s\n\n", funcname);
2230 fprintf (file, ";; \n%d basic blocks, %d edges, last basic block %d.\n\n",
2231 n_basic_blocks, n_edges, last_basic_block);
2233 brief_dump_cfg (file);
2234 fprintf (file, "\n");
2237 if (flags & TDF_STATS)
2238 dump_cfg_stats (file);
2240 dump_function_to_file (current_function_decl, file, flags | TDF_BLOCKS);
2244 /* Dump CFG statistics on FILE. */
2247 dump_cfg_stats (FILE *file)
2249 static long max_num_merged_labels = 0;
2250 unsigned long size, total = 0;
2253 const char * const fmt_str = "%-30s%-13s%12s\n";
2254 const char * const fmt_str_1 = "%-30s%13d%11lu%c\n";
2255 const char * const fmt_str_2 = "%-30s%13ld%11lu%c\n";
2256 const char * const fmt_str_3 = "%-43s%11lu%c\n";
2257 const char *funcname
2258 = lang_hooks.decl_printable_name (current_function_decl, 2);
2261 fprintf (file, "\nCFG Statistics for %s\n\n", funcname);
2263 fprintf (file, "---------------------------------------------------------\n");
2264 fprintf (file, fmt_str, "", " Number of ", "Memory");
2265 fprintf (file, fmt_str, "", " instances ", "used ");
2266 fprintf (file, "---------------------------------------------------------\n");
2268 size = n_basic_blocks * sizeof (struct basic_block_def);
2270 fprintf (file, fmt_str_1, "Basic blocks", n_basic_blocks,
2271 SCALE (size), LABEL (size));
2275 num_edges += EDGE_COUNT (bb->succs);
2276 size = num_edges * sizeof (struct edge_def);
2278 fprintf (file, fmt_str_2, "Edges", num_edges, SCALE (size), LABEL (size));
2280 fprintf (file, "---------------------------------------------------------\n");
2281 fprintf (file, fmt_str_3, "Total memory used by CFG data", SCALE (total),
2283 fprintf (file, "---------------------------------------------------------\n");
2284 fprintf (file, "\n");
2286 if (cfg_stats.num_merged_labels > max_num_merged_labels)
2287 max_num_merged_labels = cfg_stats.num_merged_labels;
2289 fprintf (file, "Coalesced label blocks: %ld (Max so far: %ld)\n",
2290 cfg_stats.num_merged_labels, max_num_merged_labels);
2292 fprintf (file, "\n");
2296 /* Dump CFG statistics on stderr. Keep extern so that it's always
2297 linked in the final executable. */
2300 debug_cfg_stats (void)
2302 dump_cfg_stats (stderr);
2306 /* Dump the flowgraph to a .vcg FILE. */
2309 tree_cfg2vcg (FILE *file)
2314 const char *funcname
2315 = lang_hooks.decl_printable_name (current_function_decl, 2);
2317 /* Write the file header. */
2318 fprintf (file, "graph: { title: \"%s\"\n", funcname);
2319 fprintf (file, "node: { title: \"ENTRY\" label: \"ENTRY\" }\n");
2320 fprintf (file, "node: { title: \"EXIT\" label: \"EXIT\" }\n");
2322 /* Write blocks and edges. */
2323 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
2325 fprintf (file, "edge: { sourcename: \"ENTRY\" targetname: \"%d\"",
2328 if (e->flags & EDGE_FAKE)
2329 fprintf (file, " linestyle: dotted priority: 10");
2331 fprintf (file, " linestyle: solid priority: 100");
2333 fprintf (file, " }\n");
2339 enum tree_code head_code, end_code;
2340 const char *head_name, *end_name;
2343 tree first = first_stmt (bb);
2344 tree last = last_stmt (bb);
2348 head_code = TREE_CODE (first);
2349 head_name = tree_code_name[head_code];
2350 head_line = get_lineno (first);
2353 head_name = "no-statement";
2357 end_code = TREE_CODE (last);
2358 end_name = tree_code_name[end_code];
2359 end_line = get_lineno (last);
2362 end_name = "no-statement";
2364 fprintf (file, "node: { title: \"%d\" label: \"#%d\\n%s (%d)\\n%s (%d)\"}\n",
2365 bb->index, bb->index, head_name, head_line, end_name,
2368 FOR_EACH_EDGE (e, ei, bb->succs)
2370 if (e->dest == EXIT_BLOCK_PTR)
2371 fprintf (file, "edge: { sourcename: \"%d\" targetname: \"EXIT\"", bb->index);
2373 fprintf (file, "edge: { sourcename: \"%d\" targetname: \"%d\"", bb->index, e->dest->index);
2375 if (e->flags & EDGE_FAKE)
2376 fprintf (file, " priority: 10 linestyle: dotted");
2378 fprintf (file, " priority: 100 linestyle: solid");
2380 fprintf (file, " }\n");
2383 if (bb->next_bb != EXIT_BLOCK_PTR)
2387 fputs ("}\n\n", file);
2392 /*---------------------------------------------------------------------------
2393 Miscellaneous helpers
2394 ---------------------------------------------------------------------------*/
2396 /* Return true if T represents a stmt that always transfers control. */
2399 is_ctrl_stmt (tree t)
2401 return (TREE_CODE (t) == COND_EXPR
2402 || TREE_CODE (t) == SWITCH_EXPR
2403 || TREE_CODE (t) == GOTO_EXPR
2404 || TREE_CODE (t) == RETURN_EXPR
2405 || TREE_CODE (t) == RESX_EXPR);
2409 /* Return true if T is a statement that may alter the flow of control
2410 (e.g., a call to a non-returning function). */
2413 is_ctrl_altering_stmt (tree t)
2418 call = get_call_expr_in (t);
2421 /* A non-pure/const CALL_EXPR alters flow control if the current
2422 function has nonlocal labels. */
2423 if (TREE_SIDE_EFFECTS (call) && current_function_has_nonlocal_label)
2426 /* A CALL_EXPR also alters control flow if it does not return. */
2427 if (call_expr_flags (call) & ECF_NORETURN)
2431 /* If a statement can throw, it alters control flow. */
2432 return tree_can_throw_internal (t);
2436 /* Return true if T is a computed goto. */
2439 computed_goto_p (tree t)
2441 return (TREE_CODE (t) == GOTO_EXPR
2442 && TREE_CODE (GOTO_DESTINATION (t)) != LABEL_DECL);
2446 /* Checks whether EXPR is a simple local goto. */
2449 simple_goto_p (tree expr)
2451 return (TREE_CODE (expr) == GOTO_EXPR
2452 && TREE_CODE (GOTO_DESTINATION (expr)) == LABEL_DECL);
2456 /* Return true if T should start a new basic block. PREV_T is the
2457 statement preceding T. It is used when T is a label or a case label.
2458 Labels should only start a new basic block if their previous statement
2459 wasn't a label. Otherwise, sequence of labels would generate
2460 unnecessary basic blocks that only contain a single label. */
2463 stmt_starts_bb_p (tree t, tree prev_t)
2468 /* LABEL_EXPRs start a new basic block only if the preceding
2469 statement wasn't a label of the same type. This prevents the
2470 creation of consecutive blocks that have nothing but a single
2472 if (TREE_CODE (t) == LABEL_EXPR)
2474 /* Nonlocal and computed GOTO targets always start a new block. */
2475 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (t))
2476 || FORCED_LABEL (LABEL_EXPR_LABEL (t)))
2479 if (prev_t && TREE_CODE (prev_t) == LABEL_EXPR)
2481 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (prev_t)))
2484 cfg_stats.num_merged_labels++;
2495 /* Return true if T should end a basic block. */
2498 stmt_ends_bb_p (tree t)
2500 return is_ctrl_stmt (t) || is_ctrl_altering_stmt (t);
2504 /* Add gotos that used to be represented implicitly in the CFG. */
2507 disband_implicit_edges (void)
2510 block_stmt_iterator last;
2517 last = bsi_last (bb);
2518 stmt = last_stmt (bb);
2520 if (stmt && TREE_CODE (stmt) == COND_EXPR)
2522 /* Remove superfluous gotos from COND_EXPR branches. Moved
2523 from cfg_remove_useless_stmts here since it violates the
2524 invariants for tree--cfg correspondence and thus fits better
2525 here where we do it anyway. */
2526 e = find_edge (bb, bb->next_bb);
2529 if (e->flags & EDGE_TRUE_VALUE)
2530 COND_EXPR_THEN (stmt) = build_empty_stmt ();
2531 else if (e->flags & EDGE_FALSE_VALUE)
2532 COND_EXPR_ELSE (stmt) = build_empty_stmt ();
2535 e->flags |= EDGE_FALLTHRU;
2541 if (stmt && TREE_CODE (stmt) == RETURN_EXPR)
2543 /* Remove the RETURN_EXPR if we may fall though to the exit
2545 gcc_assert (single_succ_p (bb));
2546 gcc_assert (single_succ (bb) == EXIT_BLOCK_PTR);
2548 if (bb->next_bb == EXIT_BLOCK_PTR
2549 && !TREE_OPERAND (stmt, 0))
2552 single_succ_edge (bb)->flags |= EDGE_FALLTHRU;
2557 /* There can be no fallthru edge if the last statement is a control
2559 if (stmt && is_ctrl_stmt (stmt))
2562 /* Find a fallthru edge and emit the goto if necessary. */
2563 FOR_EACH_EDGE (e, ei, bb->succs)
2564 if (e->flags & EDGE_FALLTHRU)
2567 if (!e || e->dest == bb->next_bb)
2570 gcc_assert (e->dest != EXIT_BLOCK_PTR);
2571 label = tree_block_label (e->dest);
2573 stmt = build1 (GOTO_EXPR, void_type_node, label);
2574 #ifdef USE_MAPPED_LOCATION
2575 SET_EXPR_LOCATION (stmt, e->goto_locus);
2577 SET_EXPR_LOCUS (stmt, e->goto_locus);
2579 bsi_insert_after (&last, stmt, BSI_NEW_STMT);
2580 e->flags &= ~EDGE_FALLTHRU;
2584 /* Remove block annotations and other datastructures. */
2587 delete_tree_cfg_annotations (void)
2589 label_to_block_map = NULL;
2593 /* Return the first statement in basic block BB. */
2596 first_stmt (basic_block bb)
2598 block_stmt_iterator i = bsi_start (bb);
2599 return !bsi_end_p (i) ? bsi_stmt (i) : NULL_TREE;
2603 /* Return the last statement in basic block BB. */
2606 last_stmt (basic_block bb)
2608 block_stmt_iterator b = bsi_last (bb);
2609 return !bsi_end_p (b) ? bsi_stmt (b) : NULL_TREE;
2613 /* Return a pointer to the last statement in block BB. */
2616 last_stmt_ptr (basic_block bb)
2618 block_stmt_iterator last = bsi_last (bb);
2619 return !bsi_end_p (last) ? bsi_stmt_ptr (last) : NULL;
2623 /* Return the last statement of an otherwise empty block. Return NULL
2624 if the block is totally empty, or if it contains more than one
2628 last_and_only_stmt (basic_block bb)
2630 block_stmt_iterator i = bsi_last (bb);
2636 last = bsi_stmt (i);
2641 /* Empty statements should no longer appear in the instruction stream.
2642 Everything that might have appeared before should be deleted by
2643 remove_useless_stmts, and the optimizers should just bsi_remove
2644 instead of smashing with build_empty_stmt.
2646 Thus the only thing that should appear here in a block containing
2647 one executable statement is a label. */
2648 prev = bsi_stmt (i);
2649 if (TREE_CODE (prev) == LABEL_EXPR)
2656 /* Mark BB as the basic block holding statement T. */
2659 set_bb_for_stmt (tree t, basic_block bb)
2661 if (TREE_CODE (t) == PHI_NODE)
2663 else if (TREE_CODE (t) == STATEMENT_LIST)
2665 tree_stmt_iterator i;
2666 for (i = tsi_start (t); !tsi_end_p (i); tsi_next (&i))
2667 set_bb_for_stmt (tsi_stmt (i), bb);
2671 stmt_ann_t ann = get_stmt_ann (t);
2674 /* If the statement is a label, add the label to block-to-labels map
2675 so that we can speed up edge creation for GOTO_EXPRs. */
2676 if (TREE_CODE (t) == LABEL_EXPR)
2680 t = LABEL_EXPR_LABEL (t);
2681 uid = LABEL_DECL_UID (t);
2684 LABEL_DECL_UID (t) = uid = cfun->last_label_uid++;
2685 if (VARRAY_SIZE (label_to_block_map) <= (unsigned) uid)
2686 VARRAY_GROW (label_to_block_map, 3 * uid / 2);
2689 /* We're moving an existing label. Make sure that we've
2690 removed it from the old block. */
2691 gcc_assert (!bb || !VARRAY_BB (label_to_block_map, uid));
2692 VARRAY_BB (label_to_block_map, uid) = bb;
2697 /* Finds iterator for STMT. */
2699 extern block_stmt_iterator
2700 bsi_for_stmt (tree stmt)
2702 block_stmt_iterator bsi;
2704 for (bsi = bsi_start (bb_for_stmt (stmt)); !bsi_end_p (bsi); bsi_next (&bsi))
2705 if (bsi_stmt (bsi) == stmt)
2711 /* Mark statement T as modified, and update it. */
2713 update_modified_stmts (tree t)
2715 if (TREE_CODE (t) == STATEMENT_LIST)
2717 tree_stmt_iterator i;
2719 for (i = tsi_start (t); !tsi_end_p (i); tsi_next (&i))
2721 stmt = tsi_stmt (i);
2722 update_stmt_if_modified (stmt);
2726 update_stmt_if_modified (t);
2729 /* Insert statement (or statement list) T before the statement
2730 pointed-to by iterator I. M specifies how to update iterator I
2731 after insertion (see enum bsi_iterator_update). */
2734 bsi_insert_before (block_stmt_iterator *i, tree t, enum bsi_iterator_update m)
2736 set_bb_for_stmt (t, i->bb);
2737 update_modified_stmts (t);
2738 tsi_link_before (&i->tsi, t, m);
2742 /* Insert statement (or statement list) T after the statement
2743 pointed-to by iterator I. M specifies how to update iterator I
2744 after insertion (see enum bsi_iterator_update). */
2747 bsi_insert_after (block_stmt_iterator *i, tree t, enum bsi_iterator_update m)
2749 set_bb_for_stmt (t, i->bb);
2750 update_modified_stmts (t);
2751 tsi_link_after (&i->tsi, t, m);
2755 /* Remove the statement pointed to by iterator I. The iterator is updated
2756 to the next statement. */
2759 bsi_remove (block_stmt_iterator *i)
2761 tree t = bsi_stmt (*i);
2762 set_bb_for_stmt (t, NULL);
2763 delink_stmt_imm_use (t);
2764 tsi_delink (&i->tsi);
2765 mark_stmt_modified (t);
2769 /* Move the statement at FROM so it comes right after the statement at TO. */
2772 bsi_move_after (block_stmt_iterator *from, block_stmt_iterator *to)
2774 tree stmt = bsi_stmt (*from);
2776 bsi_insert_after (to, stmt, BSI_SAME_STMT);
2780 /* Move the statement at FROM so it comes right before the statement at TO. */
2783 bsi_move_before (block_stmt_iterator *from, block_stmt_iterator *to)
2785 tree stmt = bsi_stmt (*from);
2787 bsi_insert_before (to, stmt, BSI_SAME_STMT);
2791 /* Move the statement at FROM to the end of basic block BB. */
2794 bsi_move_to_bb_end (block_stmt_iterator *from, basic_block bb)
2796 block_stmt_iterator last = bsi_last (bb);
2798 /* Have to check bsi_end_p because it could be an empty block. */
2799 if (!bsi_end_p (last) && is_ctrl_stmt (bsi_stmt (last)))
2800 bsi_move_before (from, &last);
2802 bsi_move_after (from, &last);
2806 /* Replace the contents of the statement pointed to by iterator BSI
2807 with STMT. If PRESERVE_EH_INFO is true, the exception handling
2808 information of the original statement is preserved. */
2811 bsi_replace (const block_stmt_iterator *bsi, tree stmt, bool preserve_eh_info)
2814 tree orig_stmt = bsi_stmt (*bsi);
2816 SET_EXPR_LOCUS (stmt, EXPR_LOCUS (orig_stmt));
2817 set_bb_for_stmt (stmt, bsi->bb);
2819 /* Preserve EH region information from the original statement, if
2820 requested by the caller. */
2821 if (preserve_eh_info)
2823 eh_region = lookup_stmt_eh_region (orig_stmt);
2825 add_stmt_to_eh_region (stmt, eh_region);
2828 delink_stmt_imm_use (orig_stmt);
2829 *bsi_stmt_ptr (*bsi) = stmt;
2830 mark_stmt_modified (stmt);
2831 update_modified_stmts (stmt);
2835 /* Insert the statement pointed-to by BSI into edge E. Every attempt
2836 is made to place the statement in an existing basic block, but
2837 sometimes that isn't possible. When it isn't possible, the edge is
2838 split and the statement is added to the new block.
2840 In all cases, the returned *BSI points to the correct location. The
2841 return value is true if insertion should be done after the location,
2842 or false if it should be done before the location. If new basic block
2843 has to be created, it is stored in *NEW_BB. */
2846 tree_find_edge_insert_loc (edge e, block_stmt_iterator *bsi,
2847 basic_block *new_bb)
2849 basic_block dest, src;
2855 /* If the destination has one predecessor which has no PHI nodes,
2856 insert there. Except for the exit block.
2858 The requirement for no PHI nodes could be relaxed. Basically we
2859 would have to examine the PHIs to prove that none of them used
2860 the value set by the statement we want to insert on E. That
2861 hardly seems worth the effort. */
2862 if (single_pred_p (dest)
2863 && ! phi_nodes (dest)
2864 && dest != EXIT_BLOCK_PTR)
2866 *bsi = bsi_start (dest);
2867 if (bsi_end_p (*bsi))
2870 /* Make sure we insert after any leading labels. */
2871 tmp = bsi_stmt (*bsi);
2872 while (TREE_CODE (tmp) == LABEL_EXPR)
2875 if (bsi_end_p (*bsi))
2877 tmp = bsi_stmt (*bsi);
2880 if (bsi_end_p (*bsi))
2882 *bsi = bsi_last (dest);
2889 /* If the source has one successor, the edge is not abnormal and
2890 the last statement does not end a basic block, insert there.
2891 Except for the entry block. */
2893 if ((e->flags & EDGE_ABNORMAL) == 0
2894 && single_succ_p (src)
2895 && src != ENTRY_BLOCK_PTR)
2897 *bsi = bsi_last (src);
2898 if (bsi_end_p (*bsi))
2901 tmp = bsi_stmt (*bsi);
2902 if (!stmt_ends_bb_p (tmp))
2905 /* Insert code just before returning the value. We may need to decompose
2906 the return in the case it contains non-trivial operand. */
2907 if (TREE_CODE (tmp) == RETURN_EXPR)
2909 tree op = TREE_OPERAND (tmp, 0);
2910 if (!is_gimple_val (op))
2912 gcc_assert (TREE_CODE (op) == MODIFY_EXPR);
2913 bsi_insert_before (bsi, op, BSI_NEW_STMT);
2914 TREE_OPERAND (tmp, 0) = TREE_OPERAND (op, 0);
2921 /* Otherwise, create a new basic block, and split this edge. */
2922 dest = split_edge (e);
2925 e = single_pred_edge (dest);
2930 /* This routine will commit all pending edge insertions, creating any new
2931 basic blocks which are necessary. */
2934 bsi_commit_edge_inserts (void)
2940 bsi_commit_one_edge_insert (single_succ_edge (ENTRY_BLOCK_PTR), NULL);
2943 FOR_EACH_EDGE (e, ei, bb->succs)
2944 bsi_commit_one_edge_insert (e, NULL);
2948 /* Commit insertions pending at edge E. If a new block is created, set NEW_BB
2949 to this block, otherwise set it to NULL. */
2952 bsi_commit_one_edge_insert (edge e, basic_block *new_bb)
2956 if (PENDING_STMT (e))
2958 block_stmt_iterator bsi;
2959 tree stmt = PENDING_STMT (e);
2961 PENDING_STMT (e) = NULL_TREE;
2963 if (tree_find_edge_insert_loc (e, &bsi, new_bb))
2964 bsi_insert_after (&bsi, stmt, BSI_NEW_STMT);
2966 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
2971 /* Add STMT to the pending list of edge E. No actual insertion is
2972 made until a call to bsi_commit_edge_inserts () is made. */
2975 bsi_insert_on_edge (edge e, tree stmt)
2977 append_to_statement_list (stmt, &PENDING_STMT (e));
2980 /* Similar to bsi_insert_on_edge+bsi_commit_edge_inserts. If a new
2981 block has to be created, it is returned. */
2984 bsi_insert_on_edge_immediate (edge e, tree stmt)
2986 block_stmt_iterator bsi;
2987 basic_block new_bb = NULL;
2989 gcc_assert (!PENDING_STMT (e));
2991 if (tree_find_edge_insert_loc (e, &bsi, &new_bb))
2992 bsi_insert_after (&bsi, stmt, BSI_NEW_STMT);
2994 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
2999 /*---------------------------------------------------------------------------
3000 Tree specific functions for CFG manipulation
3001 ---------------------------------------------------------------------------*/
3003 /* Reinstall those PHI arguments queued in OLD_EDGE to NEW_EDGE. */
3006 reinstall_phi_args (edge new_edge, edge old_edge)
3010 if (!PENDING_STMT (old_edge))
3013 for (var = PENDING_STMT (old_edge), phi = phi_nodes (new_edge->dest);
3015 var = TREE_CHAIN (var), phi = PHI_CHAIN (phi))
3017 tree result = TREE_PURPOSE (var);
3018 tree arg = TREE_VALUE (var);
3020 gcc_assert (result == PHI_RESULT (phi));
3022 add_phi_arg (phi, arg, new_edge);
3025 PENDING_STMT (old_edge) = NULL;
3028 /* Split a (typically critical) edge EDGE_IN. Return the new block.
3029 Abort on abnormal edges. */
3032 tree_split_edge (edge edge_in)
3034 basic_block new_bb, after_bb, dest, src;
3037 /* Abnormal edges cannot be split. */
3038 gcc_assert (!(edge_in->flags & EDGE_ABNORMAL));
3041 dest = edge_in->dest;
3043 /* Place the new block in the block list. Try to keep the new block
3044 near its "logical" location. This is of most help to humans looking
3045 at debugging dumps. */
3046 if (dest->prev_bb && find_edge (dest->prev_bb, dest))
3047 after_bb = edge_in->src;
3049 after_bb = dest->prev_bb;
3051 new_bb = create_empty_bb (after_bb);
3052 new_bb->frequency = EDGE_FREQUENCY (edge_in);
3053 new_bb->count = edge_in->count;
3054 new_edge = make_edge (new_bb, dest, EDGE_FALLTHRU);
3055 new_edge->probability = REG_BR_PROB_BASE;
3056 new_edge->count = edge_in->count;
3058 e = redirect_edge_and_branch (edge_in, new_bb);
3060 reinstall_phi_args (new_edge, e);
3066 /* Return true when BB has label LABEL in it. */
3069 has_label_p (basic_block bb, tree label)
3071 block_stmt_iterator bsi;
3073 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3075 tree stmt = bsi_stmt (bsi);
3077 if (TREE_CODE (stmt) != LABEL_EXPR)
3079 if (LABEL_EXPR_LABEL (stmt) == label)
3086 /* Callback for walk_tree, check that all elements with address taken are
3087 properly noticed as such. The DATA is an int* that is 1 if TP was seen
3088 inside a PHI node. */
3091 verify_expr (tree *tp, int *walk_subtrees, void *data ATTRIBUTE_UNUSED)
3094 bool in_phi = (data != NULL);
3099 /* Check operand N for being valid GIMPLE and give error MSG if not. */
3100 #define CHECK_OP(N, MSG) \
3101 do { if (!is_gimple_val (TREE_OPERAND (t, N))) \
3102 { error (MSG); return TREE_OPERAND (t, N); }} while (0)
3104 switch (TREE_CODE (t))
3107 if (SSA_NAME_IN_FREE_LIST (t))
3109 error ("SSA name in freelist but still referenced");
3115 x = fold (ASSERT_EXPR_COND (t));
3116 if (x == boolean_false_node)
3118 error ("ASSERT_EXPR with an always-false condition");
3124 x = TREE_OPERAND (t, 0);
3125 if (TREE_CODE (x) == BIT_FIELD_REF
3126 && is_gimple_reg (TREE_OPERAND (x, 0)))
3128 error ("GIMPLE register modified with BIT_FIELD_REF");
3137 bool old_side_effects;
3140 bool new_side_effects;
3142 /* ??? tree-ssa-alias.c may have overlooked dead PHI nodes, missing
3143 dead PHIs that take the address of something. But if the PHI
3144 result is dead, the fact that it takes the address of anything
3145 is irrelevant. Because we can not tell from here if a PHI result
3146 is dead, we just skip this check for PHIs altogether. This means
3147 we may be missing "valid" checks, but what can you do?
3148 This was PR19217. */
3152 old_invariant = TREE_INVARIANT (t);
3153 old_constant = TREE_CONSTANT (t);
3154 old_side_effects = TREE_SIDE_EFFECTS (t);
3156 recompute_tree_invarant_for_addr_expr (t);
3157 new_invariant = TREE_INVARIANT (t);
3158 new_side_effects = TREE_SIDE_EFFECTS (t);
3159 new_constant = TREE_CONSTANT (t);
3161 if (old_invariant != new_invariant)
3163 error ("invariant not recomputed when ADDR_EXPR changed");
3167 if (old_constant != new_constant)
3169 error ("constant not recomputed when ADDR_EXPR changed");
3172 if (old_side_effects != new_side_effects)
3174 error ("side effects not recomputed when ADDR_EXPR changed");
3178 /* Skip any references (they will be checked when we recurse down the
3179 tree) and ensure that any variable used as a prefix is marked
3181 for (x = TREE_OPERAND (t, 0);
3182 handled_component_p (x);
3183 x = TREE_OPERAND (x, 0))
3186 if (TREE_CODE (x) != VAR_DECL && TREE_CODE (x) != PARM_DECL)
3188 if (!TREE_ADDRESSABLE (x))
3190 error ("address taken, but ADDRESSABLE bit not set");
3197 x = COND_EXPR_COND (t);
3198 if (TREE_CODE (TREE_TYPE (x)) != BOOLEAN_TYPE)
3200 error ("non-boolean used in condition");
3203 if (!is_gimple_condexpr (x))
3205 error ("invalid conditional operand");
3212 case FIX_TRUNC_EXPR:
3214 case FIX_FLOOR_EXPR:
3215 case FIX_ROUND_EXPR:
3220 case NON_LVALUE_EXPR:
3221 case TRUTH_NOT_EXPR:
3222 CHECK_OP (0, "invalid operand to unary operator");
3229 case ARRAY_RANGE_REF:
3231 case VIEW_CONVERT_EXPR:
3232 /* We have a nest of references. Verify that each of the operands
3233 that determine where to reference is either a constant or a variable,
3234 verify that the base is valid, and then show we've already checked
3236 while (handled_component_p (t))
3238 if (TREE_CODE (t) == COMPONENT_REF && TREE_OPERAND (t, 2))
3239 CHECK_OP (2, "invalid COMPONENT_REF offset operator");
3240 else if (TREE_CODE (t) == ARRAY_REF
3241 || TREE_CODE (t) == ARRAY_RANGE_REF)
3243 CHECK_OP (1, "invalid array index");
3244 if (TREE_OPERAND (t, 2))
3245 CHECK_OP (2, "invalid array lower bound");
3246 if (TREE_OPERAND (t, 3))
3247 CHECK_OP (3, "invalid array stride");
3249 else if (TREE_CODE (t) == BIT_FIELD_REF)
3251 CHECK_OP (1, "invalid operand to BIT_FIELD_REF");
3252 CHECK_OP (2, "invalid operand to BIT_FIELD_REF");
3255 t = TREE_OPERAND (t, 0);
3258 if (!CONSTANT_CLASS_P (t) && !is_gimple_lvalue (t))
3260 error ("invalid reference prefix");
3272 case UNORDERED_EXPR:
3283 case TRUNC_DIV_EXPR:
3285 case FLOOR_DIV_EXPR:
3286 case ROUND_DIV_EXPR:
3287 case TRUNC_MOD_EXPR:
3289 case FLOOR_MOD_EXPR:
3290 case ROUND_MOD_EXPR:
3292 case EXACT_DIV_EXPR:
3302 CHECK_OP (0, "invalid operand to binary operator");
3303 CHECK_OP (1, "invalid operand to binary operator");
3315 /* Verify STMT, return true if STMT is not in GIMPLE form.
3316 TODO: Implement type checking. */
3319 verify_stmt (tree stmt, bool last_in_block)
3323 if (!is_gimple_stmt (stmt))
3325 error ("is not a valid GIMPLE statement");
3329 addr = walk_tree (&stmt, verify_expr, NULL, NULL);
3332 debug_generic_stmt (addr);
3336 /* If the statement is marked as part of an EH region, then it is
3337 expected that the statement could throw. Verify that when we
3338 have optimizations that simplify statements such that we prove
3339 that they cannot throw, that we update other data structures
3341 if (lookup_stmt_eh_region (stmt) >= 0)
3343 if (!tree_could_throw_p (stmt))
3345 error ("statement marked for throw, but doesn%'t");
3348 if (!last_in_block && tree_can_throw_internal (stmt))
3350 error ("statement marked for throw in middle of block");
3358 debug_generic_stmt (stmt);
3363 /* Return true when the T can be shared. */
3366 tree_node_can_be_shared (tree t)
3368 if (IS_TYPE_OR_DECL_P (t)
3369 /* We check for constants explicitly since they are not considered
3370 gimple invariants if they overflowed. */
3371 || CONSTANT_CLASS_P (t)
3372 || is_gimple_min_invariant (t)
3373 || TREE_CODE (t) == SSA_NAME
3374 || t == error_mark_node)
3377 if (TREE_CODE (t) == CASE_LABEL_EXPR)
3380 while (((TREE_CODE (t) == ARRAY_REF || TREE_CODE (t) == ARRAY_RANGE_REF)
3381 /* We check for constants explicitly since they are not considered
3382 gimple invariants if they overflowed. */
3383 && (CONSTANT_CLASS_P (TREE_OPERAND (t, 1))
3384 || is_gimple_min_invariant (TREE_OPERAND (t, 1))))
3385 || (TREE_CODE (t) == COMPONENT_REF
3386 || TREE_CODE (t) == REALPART_EXPR
3387 || TREE_CODE (t) == IMAGPART_EXPR))
3388 t = TREE_OPERAND (t, 0);
3397 /* Called via walk_trees. Verify tree sharing. */
3400 verify_node_sharing (tree * tp, int *walk_subtrees, void *data)
3402 htab_t htab = (htab_t) data;
3405 if (tree_node_can_be_shared (*tp))
3407 *walk_subtrees = false;
3411 slot = htab_find_slot (htab, *tp, INSERT);
3420 /* Verify the GIMPLE statement chain. */
3426 block_stmt_iterator bsi;
3431 timevar_push (TV_TREE_STMT_VERIFY);
3432 htab = htab_create (37, htab_hash_pointer, htab_eq_pointer, NULL);
3439 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
3441 int phi_num_args = PHI_NUM_ARGS (phi);
3443 if (bb_for_stmt (phi) != bb)
3445 error ("bb_for_stmt (phi) is set to a wrong basic block");
3449 for (i = 0; i < phi_num_args; i++)
3451 tree t = PHI_ARG_DEF (phi, i);
3454 /* Addressable variables do have SSA_NAMEs but they
3455 are not considered gimple values. */
3456 if (TREE_CODE (t) != SSA_NAME
3457 && TREE_CODE (t) != FUNCTION_DECL
3458 && !is_gimple_val (t))
3460 error ("PHI def is not a GIMPLE value");
3461 debug_generic_stmt (phi);
3462 debug_generic_stmt (t);
3466 addr = walk_tree (&t, verify_expr, (void *) 1, NULL);
3469 debug_generic_stmt (addr);
3473 addr = walk_tree (&t, verify_node_sharing, htab, NULL);
3476 error ("incorrect sharing of tree nodes");
3477 debug_generic_stmt (phi);
3478 debug_generic_stmt (addr);
3484 for (bsi = bsi_start (bb); !bsi_end_p (bsi); )
3486 tree stmt = bsi_stmt (bsi);
3488 if (bb_for_stmt (stmt) != bb)
3490 error ("bb_for_stmt (stmt) is set to a wrong basic block");
3495 err |= verify_stmt (stmt, bsi_end_p (bsi));
3496 addr = walk_tree (&stmt, verify_node_sharing, htab, NULL);
3499 error ("incorrect sharing of tree nodes");
3500 debug_generic_stmt (stmt);
3501 debug_generic_stmt (addr);
3508 internal_error ("verify_stmts failed");
3511 timevar_pop (TV_TREE_STMT_VERIFY);
3515 /* Verifies that the flow information is OK. */
3518 tree_verify_flow_info (void)
3522 block_stmt_iterator bsi;
3527 if (ENTRY_BLOCK_PTR->stmt_list)
3529 error ("ENTRY_BLOCK has a statement list associated with it");
3533 if (EXIT_BLOCK_PTR->stmt_list)
3535 error ("EXIT_BLOCK has a statement list associated with it");
3539 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
3540 if (e->flags & EDGE_FALLTHRU)
3542 error ("fallthru to exit from bb %d", e->src->index);
3548 bool found_ctrl_stmt = false;
3552 /* Skip labels on the start of basic block. */
3553 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3555 tree prev_stmt = stmt;
3557 stmt = bsi_stmt (bsi);
3559 if (TREE_CODE (stmt) != LABEL_EXPR)
3562 if (prev_stmt && DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)))
3564 error ("nonlocal label %s is not first "
3565 "in a sequence of labels in bb %d",
3566 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt))),
3571 if (label_to_block (LABEL_EXPR_LABEL (stmt)) != bb)
3573 error ("label %s to block does not match in bb %d",
3574 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt))),
3579 if (decl_function_context (LABEL_EXPR_LABEL (stmt))
3580 != current_function_decl)
3582 error ("label %s has incorrect context in bb %d",
3583 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt))),
3589 /* Verify that body of basic block BB is free of control flow. */
3590 for (; !bsi_end_p (bsi); bsi_next (&bsi))
3592 tree stmt = bsi_stmt (bsi);
3594 if (found_ctrl_stmt)
3596 error ("control flow in the middle of basic block %d",
3601 if (stmt_ends_bb_p (stmt))
3602 found_ctrl_stmt = true;
3604 if (TREE_CODE (stmt) == LABEL_EXPR)
3606 error ("label %s in the middle of basic block %d",
3607 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt))),
3612 bsi = bsi_last (bb);
3613 if (bsi_end_p (bsi))
3616 stmt = bsi_stmt (bsi);
3618 err |= verify_eh_edges (stmt);
3620 if (is_ctrl_stmt (stmt))
3622 FOR_EACH_EDGE (e, ei, bb->succs)
3623 if (e->flags & EDGE_FALLTHRU)
3625 error ("fallthru edge after a control statement in bb %d",
3631 switch (TREE_CODE (stmt))
3637 if (TREE_CODE (COND_EXPR_THEN (stmt)) != GOTO_EXPR
3638 || TREE_CODE (COND_EXPR_ELSE (stmt)) != GOTO_EXPR)
3640 error ("structured COND_EXPR at the end of bb %d", bb->index);
3644 extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
3646 if (!true_edge || !false_edge
3647 || !(true_edge->flags & EDGE_TRUE_VALUE)
3648 || !(false_edge->flags & EDGE_FALSE_VALUE)
3649 || (true_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL))
3650 || (false_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL))
3651 || EDGE_COUNT (bb->succs) >= 3)
3653 error ("wrong outgoing edge flags at end of bb %d",
3658 if (!has_label_p (true_edge->dest,
3659 GOTO_DESTINATION (COND_EXPR_THEN (stmt))))
3661 error ("%<then%> label does not match edge at end of bb %d",
3666 if (!has_label_p (false_edge->dest,
3667 GOTO_DESTINATION (COND_EXPR_ELSE (stmt))))
3669 error ("%<else%> label does not match edge at end of bb %d",
3677 if (simple_goto_p (stmt))
3679 error ("explicit goto at end of bb %d", bb->index);
3684 /* FIXME. We should double check that the labels in the
3685 destination blocks have their address taken. */
3686 FOR_EACH_EDGE (e, ei, bb->succs)
3687 if ((e->flags & (EDGE_FALLTHRU | EDGE_TRUE_VALUE
3688 | EDGE_FALSE_VALUE))
3689 || !(e->flags & EDGE_ABNORMAL))
3691 error ("wrong outgoing edge flags at end of bb %d",
3699 if (!single_succ_p (bb)
3700 || (single_succ_edge (bb)->flags
3701 & (EDGE_FALLTHRU | EDGE_ABNORMAL
3702 | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
3704 error ("wrong outgoing edge flags at end of bb %d", bb->index);
3707 if (single_succ (bb) != EXIT_BLOCK_PTR)
3709 error ("return edge does not point to exit in bb %d",
3722 vec = SWITCH_LABELS (stmt);
3723 n = TREE_VEC_LENGTH (vec);
3725 /* Mark all the destination basic blocks. */
3726 for (i = 0; i < n; ++i)
3728 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
3729 basic_block label_bb = label_to_block (lab);
3731 gcc_assert (!label_bb->aux || label_bb->aux == (void *)1);
3732 label_bb->aux = (void *)1;
3735 /* Verify that the case labels are sorted. */
3736 prev = TREE_VEC_ELT (vec, 0);
3737 for (i = 1; i < n - 1; ++i)
3739 tree c = TREE_VEC_ELT (vec, i);
3742 error ("found default case not at end of case vector");
3746 if (! tree_int_cst_lt (CASE_LOW (prev), CASE_LOW (c)))
3748 error ("case labels not sorted:");
3749 print_generic_expr (stderr, prev, 0);
3750 fprintf (stderr," is greater than ");
3751 print_generic_expr (stderr, c, 0);
3752 fprintf (stderr," but comes before it.\n");
3757 if (CASE_LOW (TREE_VEC_ELT (vec, n - 1)))
3759 error ("no default case found at end of case vector");
3763 FOR_EACH_EDGE (e, ei, bb->succs)
3767 error ("extra outgoing edge %d->%d",
3768 bb->index, e->dest->index);
3771 e->dest->aux = (void *)2;
3772 if ((e->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL
3773 | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
3775 error ("wrong outgoing edge flags at end of bb %d",
3781 /* Check that we have all of them. */
3782 for (i = 0; i < n; ++i)
3784 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
3785 basic_block label_bb = label_to_block (lab);
3787 if (label_bb->aux != (void *)2)
3789 error ("missing edge %i->%i",
3790 bb->index, label_bb->index);
3795 FOR_EACH_EDGE (e, ei, bb->succs)
3796 e->dest->aux = (void *)0;
3803 if (dom_computed[CDI_DOMINATORS] >= DOM_NO_FAST_QUERY)
3804 verify_dominators (CDI_DOMINATORS);
3810 /* Updates phi nodes after creating a forwarder block joined
3811 by edge FALLTHRU. */
3814 tree_make_forwarder_block (edge fallthru)
3818 basic_block dummy, bb;
3819 tree phi, new_phi, var;
3821 dummy = fallthru->src;
3822 bb = fallthru->dest;
3824 if (single_pred_p (bb))
3827 /* If we redirected a branch we must create new phi nodes at the
3829 for (phi = phi_nodes (dummy); phi; phi = PHI_CHAIN (phi))
3831 var = PHI_RESULT (phi);
3832 new_phi = create_phi_node (var, bb);
3833 SSA_NAME_DEF_STMT (var) = new_phi;
3834 SET_PHI_RESULT (phi, make_ssa_name (SSA_NAME_VAR (var), phi));
3835 add_phi_arg (new_phi, PHI_RESULT (phi), fallthru);
3838 /* Ensure that the PHI node chain is in the same order. */
3839 set_phi_nodes (bb, phi_reverse (phi_nodes (bb)));
3841 /* Add the arguments we have stored on edges. */
3842 FOR_EACH_EDGE (e, ei, bb->preds)
3847 flush_pending_stmts (e);
3852 /* Return a non-special label in the head of basic block BLOCK.
3853 Create one if it doesn't exist. */
3856 tree_block_label (basic_block bb)
3858 block_stmt_iterator i, s = bsi_start (bb);
3862 for (i = s; !bsi_end_p (i); first = false, bsi_next (&i))
3864 stmt = bsi_stmt (i);
3865 if (TREE_CODE (stmt) != LABEL_EXPR)
3867 label = LABEL_EXPR_LABEL (stmt);
3868 if (!DECL_NONLOCAL (label))
3871 bsi_move_before (&i, &s);
3876 label = create_artificial_label ();
3877 stmt = build1 (LABEL_EXPR, void_type_node, label);
3878 bsi_insert_before (&s, stmt, BSI_NEW_STMT);
3883 /* Attempt to perform edge redirection by replacing a possibly complex
3884 jump instruction by a goto or by removing the jump completely.
3885 This can apply only if all edges now point to the same block. The
3886 parameters and return values are equivalent to
3887 redirect_edge_and_branch. */
3890 tree_try_redirect_by_replacing_jump (edge e, basic_block target)
3892 basic_block src = e->src;
3893 block_stmt_iterator b;
3896 /* We can replace or remove a complex jump only when we have exactly
3898 if (EDGE_COUNT (src->succs) != 2
3899 /* Verify that all targets will be TARGET. Specifically, the
3900 edge that is not E must also go to TARGET. */
3901 || EDGE_SUCC (src, EDGE_SUCC (src, 0) == e)->dest != target)
3907 stmt = bsi_stmt (b);
3909 if (TREE_CODE (stmt) == COND_EXPR
3910 || TREE_CODE (stmt) == SWITCH_EXPR)
3913 e = ssa_redirect_edge (e, target);
3914 e->flags = EDGE_FALLTHRU;
3922 /* Redirect E to DEST. Return NULL on failure. Otherwise, return the
3923 edge representing the redirected branch. */
3926 tree_redirect_edge_and_branch (edge e, basic_block dest)
3928 basic_block bb = e->src;
3929 block_stmt_iterator bsi;
3933 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
3936 if (e->src != ENTRY_BLOCK_PTR
3937 && (ret = tree_try_redirect_by_replacing_jump (e, dest)))
3940 if (e->dest == dest)
3943 label = tree_block_label (dest);
3945 bsi = bsi_last (bb);
3946 stmt = bsi_end_p (bsi) ? NULL : bsi_stmt (bsi);
3948 switch (stmt ? TREE_CODE (stmt) : ERROR_MARK)
3951 stmt = (e->flags & EDGE_TRUE_VALUE
3952 ? COND_EXPR_THEN (stmt)
3953 : COND_EXPR_ELSE (stmt));
3954 GOTO_DESTINATION (stmt) = label;
3958 /* No non-abnormal edges should lead from a non-simple goto, and
3959 simple ones should be represented implicitly. */
3964 tree cases = get_cases_for_edge (e, stmt);
3966 /* If we have a list of cases associated with E, then use it
3967 as it's a lot faster than walking the entire case vector. */
3970 edge e2 = find_edge (e->src, dest);
3977 CASE_LABEL (cases) = label;
3978 cases = TREE_CHAIN (cases);
3981 /* If there was already an edge in the CFG, then we need
3982 to move all the cases associated with E to E2. */
3985 tree cases2 = get_cases_for_edge (e2, stmt);
3987 TREE_CHAIN (last) = TREE_CHAIN (cases2);
3988 TREE_CHAIN (cases2) = first;
3993 tree vec = SWITCH_LABELS (stmt);
3994 size_t i, n = TREE_VEC_LENGTH (vec);
3996 for (i = 0; i < n; i++)
3998 tree elt = TREE_VEC_ELT (vec, i);
4000 if (label_to_block (CASE_LABEL (elt)) == e->dest)
4001 CASE_LABEL (elt) = label;
4010 e->flags |= EDGE_FALLTHRU;
4014 /* Otherwise it must be a fallthru edge, and we don't need to
4015 do anything besides redirecting it. */
4016 gcc_assert (e->flags & EDGE_FALLTHRU);
4020 /* Update/insert PHI nodes as necessary. */
4022 /* Now update the edges in the CFG. */
4023 e = ssa_redirect_edge (e, dest);
4029 /* Simple wrapper, as we can always redirect fallthru edges. */
4032 tree_redirect_edge_and_branch_force (edge e, basic_block dest)
4034 e = tree_redirect_edge_and_branch (e, dest);
4041 /* Splits basic block BB after statement STMT (but at least after the
4042 labels). If STMT is NULL, BB is split just after the labels. */
4045 tree_split_block (basic_block bb, void *stmt)
4047 block_stmt_iterator bsi, bsi_tgt;
4053 new_bb = create_empty_bb (bb);
4055 /* Redirect the outgoing edges. */
4056 new_bb->succs = bb->succs;
4058 FOR_EACH_EDGE (e, ei, new_bb->succs)
4061 if (stmt && TREE_CODE ((tree) stmt) == LABEL_EXPR)
4064 /* Move everything from BSI to the new basic block. */
4065 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4067 act = bsi_stmt (bsi);
4068 if (TREE_CODE (act) == LABEL_EXPR)
4081 bsi_tgt = bsi_start (new_bb);
4082 while (!bsi_end_p (bsi))
4084 act = bsi_stmt (bsi);
4086 bsi_insert_after (&bsi_tgt, act, BSI_NEW_STMT);
4093 /* Moves basic block BB after block AFTER. */
4096 tree_move_block_after (basic_block bb, basic_block after)
4098 if (bb->prev_bb == after)
4102 link_block (bb, after);
4108 /* Return true if basic_block can be duplicated. */
4111 tree_can_duplicate_bb_p (basic_block bb ATTRIBUTE_UNUSED)
4117 /* Create a duplicate of the basic block BB. NOTE: This does not
4118 preserve SSA form. */
4121 tree_duplicate_bb (basic_block bb)
4124 block_stmt_iterator bsi, bsi_tgt;
4127 new_bb = create_empty_bb (EXIT_BLOCK_PTR->prev_bb);
4129 /* Copy the PHI nodes. We ignore PHI node arguments here because
4130 the incoming edges have not been setup yet. */
4131 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
4133 tree copy = create_phi_node (PHI_RESULT (phi), new_bb);
4134 create_new_def_for (PHI_RESULT (copy), copy, PHI_RESULT_PTR (copy));
4137 /* Keep the chain of PHI nodes in the same order so that they can be
4138 updated by ssa_redirect_edge. */
4139 set_phi_nodes (new_bb, phi_reverse (phi_nodes (new_bb)));
4141 bsi_tgt = bsi_start (new_bb);
4142 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4144 def_operand_p def_p;
4145 ssa_op_iter op_iter;
4149 stmt = bsi_stmt (bsi);
4150 if (TREE_CODE (stmt) == LABEL_EXPR)
4153 /* Create a new copy of STMT and duplicate STMT's virtual
4155 copy = unshare_expr (stmt);
4156 bsi_insert_after (&bsi_tgt, copy, BSI_NEW_STMT);
4157 copy_virtual_operands (copy, stmt);
4158 region = lookup_stmt_eh_region (stmt);
4160 add_stmt_to_eh_region (copy, region);
4162 /* Create new names for all the definitions created by COPY and
4163 add replacement mappings for each new name. */
4164 FOR_EACH_SSA_DEF_OPERAND (def_p, copy, op_iter, SSA_OP_ALL_DEFS)
4165 create_new_def_for (DEF_FROM_PTR (def_p), copy, def_p);
4172 /* Basic block BB_COPY was created by code duplication. Add phi node
4173 arguments for edges going out of BB_COPY. The blocks that were
4174 duplicated have BB_DUPLICATED set. */
4177 add_phi_args_after_copy_bb (basic_block bb_copy)
4179 basic_block bb, dest;
4182 tree phi, phi_copy, phi_next, def;
4184 bb = get_bb_original (bb_copy);
4186 FOR_EACH_EDGE (e_copy, ei, bb_copy->succs)
4188 if (!phi_nodes (e_copy->dest))
4191 if (e_copy->dest->flags & BB_DUPLICATED)
4192 dest = get_bb_original (e_copy->dest);
4194 dest = e_copy->dest;
4196 e = find_edge (bb, dest);
4199 /* During loop unrolling the target of the latch edge is copied.
4200 In this case we are not looking for edge to dest, but to
4201 duplicated block whose original was dest. */
4202 FOR_EACH_EDGE (e, ei, bb->succs)
4203 if ((e->dest->flags & BB_DUPLICATED)
4204 && get_bb_original (e->dest) == dest)
4207 gcc_assert (e != NULL);
4210 for (phi = phi_nodes (e->dest), phi_copy = phi_nodes (e_copy->dest);
4212 phi = phi_next, phi_copy = PHI_CHAIN (phi_copy))
4214 phi_next = PHI_CHAIN (phi);
4215 def = PHI_ARG_DEF_FROM_EDGE (phi, e);
4216 add_phi_arg (phi_copy, def, e_copy);
4221 /* Blocks in REGION_COPY array of length N_REGION were created by
4222 duplication of basic blocks. Add phi node arguments for edges
4223 going from these blocks. */
4226 add_phi_args_after_copy (basic_block *region_copy, unsigned n_region)
4230 for (i = 0; i < n_region; i++)
4231 region_copy[i]->flags |= BB_DUPLICATED;
4233 for (i = 0; i < n_region; i++)
4234 add_phi_args_after_copy_bb (region_copy[i]);
4236 for (i = 0; i < n_region; i++)
4237 region_copy[i]->flags &= ~BB_DUPLICATED;
4240 /* Duplicates a REGION (set of N_REGION basic blocks) with just a single
4241 important exit edge EXIT. By important we mean that no SSA name defined
4242 inside region is live over the other exit edges of the region. All entry
4243 edges to the region must go to ENTRY->dest. The edge ENTRY is redirected
4244 to the duplicate of the region. SSA form, dominance and loop information
4245 is updated. The new basic blocks are stored to REGION_COPY in the same
4246 order as they had in REGION, provided that REGION_COPY is not NULL.
4247 The function returns false if it is unable to copy the region,
4251 tree_duplicate_sese_region (edge entry, edge exit,
4252 basic_block *region, unsigned n_region,
4253 basic_block *region_copy)
4256 bool free_region_copy = false, copying_header = false;
4257 struct loop *loop = entry->dest->loop_father;
4261 int total_freq = 0, entry_freq = 0;
4262 gcov_type total_count = 0, entry_count = 0;
4264 if (!can_copy_bbs_p (region, n_region))
4267 /* Some sanity checking. Note that we do not check for all possible
4268 missuses of the functions. I.e. if you ask to copy something weird,
4269 it will work, but the state of structures probably will not be
4271 for (i = 0; i < n_region; i++)
4273 /* We do not handle subloops, i.e. all the blocks must belong to the
4275 if (region[i]->loop_father != loop)
4278 if (region[i] != entry->dest
4279 && region[i] == loop->header)
4285 /* In case the function is used for loop header copying (which is the primary
4286 use), ensure that EXIT and its copy will be new latch and entry edges. */
4287 if (loop->header == entry->dest)
4289 copying_header = true;
4290 loop->copy = loop->outer;
4292 if (!dominated_by_p (CDI_DOMINATORS, loop->latch, exit->src))
4295 for (i = 0; i < n_region; i++)
4296 if (region[i] != exit->src
4297 && dominated_by_p (CDI_DOMINATORS, region[i], exit->src))
4303 region_copy = xmalloc (sizeof (basic_block) * n_region);
4304 free_region_copy = true;
4307 gcc_assert (!need_ssa_update_p ());
4309 /* Record blocks outside the region that are dominated by something
4311 doms = xmalloc (sizeof (basic_block) * n_basic_blocks);
4312 initialize_original_copy_tables ();
4314 n_doms = get_dominated_by_region (CDI_DOMINATORS, region, n_region, doms);
4316 if (entry->dest->count)
4318 total_count = entry->dest->count;
4319 entry_count = entry->count;
4320 /* Fix up corner cases, to avoid division by zero or creation of negative
4322 if (entry_count > total_count)
4323 entry_count = total_count;
4327 total_freq = entry->dest->frequency;
4328 entry_freq = EDGE_FREQUENCY (entry);
4329 /* Fix up corner cases, to avoid division by zero or creation of negative
4331 if (total_freq == 0)
4333 else if (entry_freq > total_freq)
4334 entry_freq = total_freq;
4337 copy_bbs (region, n_region, region_copy, &exit, 1, &exit_copy, loop);
4340 scale_bbs_frequencies_gcov_type (region, n_region,
4341 total_count - entry_count,
4343 scale_bbs_frequencies_gcov_type (region_copy, n_region, entry_count,
4348 scale_bbs_frequencies_int (region, n_region, total_freq - entry_freq,
4350 scale_bbs_frequencies_int (region_copy, n_region, entry_freq, total_freq);
4355 loop->header = exit->dest;
4356 loop->latch = exit->src;
4359 /* Redirect the entry and add the phi node arguments. */
4360 redirected = redirect_edge_and_branch (entry, get_bb_copy (entry->dest));
4361 gcc_assert (redirected != NULL);
4362 flush_pending_stmts (entry);
4364 /* Concerning updating of dominators: We must recount dominators
4365 for entry block and its copy. Anything that is outside of the
4366 region, but was dominated by something inside needs recounting as
4368 set_immediate_dominator (CDI_DOMINATORS, entry->dest, entry->src);
4369 doms[n_doms++] = get_bb_original (entry->dest);
4370 iterate_fix_dominators (CDI_DOMINATORS, doms, n_doms);
4373 /* Add the other PHI node arguments. */
4374 add_phi_args_after_copy (region_copy, n_region);
4376 /* Update the SSA web. */
4377 update_ssa (TODO_update_ssa);
4379 if (free_region_copy)
4382 free_original_copy_tables ();
4387 /* Dump FUNCTION_DECL FN to file FILE using FLAGS (see TDF_* in tree.h) */
4390 dump_function_to_file (tree fn, FILE *file, int flags)
4392 tree arg, vars, var;
4393 bool ignore_topmost_bind = false, any_var = false;
4397 fprintf (file, "%s (", lang_hooks.decl_printable_name (fn, 2));
4399 arg = DECL_ARGUMENTS (fn);
4402 print_generic_expr (file, arg, dump_flags);
4403 if (TREE_CHAIN (arg))
4404 fprintf (file, ", ");
4405 arg = TREE_CHAIN (arg);
4407 fprintf (file, ")\n");
4409 if (flags & TDF_DETAILS)
4410 dump_eh_tree (file, DECL_STRUCT_FUNCTION (fn));
4411 if (flags & TDF_RAW)
4413 dump_node (fn, TDF_SLIM | flags, file);
4417 /* When GIMPLE is lowered, the variables are no longer available in
4418 BIND_EXPRs, so display them separately. */
4419 if (cfun && cfun->decl == fn && cfun->unexpanded_var_list)
4421 ignore_topmost_bind = true;
4423 fprintf (file, "{\n");
4424 for (vars = cfun->unexpanded_var_list; vars; vars = TREE_CHAIN (vars))
4426 var = TREE_VALUE (vars);
4428 print_generic_decl (file, var, flags);
4429 fprintf (file, "\n");
4435 if (cfun && cfun->decl == fn && cfun->cfg && basic_block_info)
4437 /* Make a CFG based dump. */
4438 check_bb_profile (ENTRY_BLOCK_PTR, file);
4439 if (!ignore_topmost_bind)
4440 fprintf (file, "{\n");
4442 if (any_var && n_basic_blocks)
4443 fprintf (file, "\n");
4446 dump_generic_bb (file, bb, 2, flags);
4448 fprintf (file, "}\n");
4449 check_bb_profile (EXIT_BLOCK_PTR, file);
4455 /* Make a tree based dump. */
4456 chain = DECL_SAVED_TREE (fn);
4458 if (TREE_CODE (chain) == BIND_EXPR)
4460 if (ignore_topmost_bind)
4462 chain = BIND_EXPR_BODY (chain);
4470 if (!ignore_topmost_bind)
4471 fprintf (file, "{\n");
4476 fprintf (file, "\n");
4478 print_generic_stmt_indented (file, chain, flags, indent);
4479 if (ignore_topmost_bind)
4480 fprintf (file, "}\n");
4483 fprintf (file, "\n\n");
4487 /* Pretty print of the loops intermediate representation. */
4488 static void print_loop (FILE *, struct loop *, int);
4489 static void print_pred_bbs (FILE *, basic_block bb);
4490 static void print_succ_bbs (FILE *, basic_block bb);
4493 /* Print the predecessors indexes of edge E on FILE. */
4496 print_pred_bbs (FILE *file, basic_block bb)
4501 FOR_EACH_EDGE (e, ei, bb->preds)
4502 fprintf (file, "bb_%d", e->src->index);
4506 /* Print the successors indexes of edge E on FILE. */
4509 print_succ_bbs (FILE *file, basic_block bb)
4514 FOR_EACH_EDGE (e, ei, bb->succs)
4515 fprintf (file, "bb_%d", e->src->index);
4519 /* Pretty print LOOP on FILE, indented INDENT spaces. */
4522 print_loop (FILE *file, struct loop *loop, int indent)
4530 s_indent = (char *) alloca ((size_t) indent + 1);
4531 memset ((void *) s_indent, ' ', (size_t) indent);
4532 s_indent[indent] = '\0';
4534 /* Print the loop's header. */
4535 fprintf (file, "%sloop_%d\n", s_indent, loop->num);
4537 /* Print the loop's body. */
4538 fprintf (file, "%s{\n", s_indent);
4540 if (bb->loop_father == loop)
4542 /* Print the basic_block's header. */
4543 fprintf (file, "%s bb_%d (preds = {", s_indent, bb->index);
4544 print_pred_bbs (file, bb);
4545 fprintf (file, "}, succs = {");
4546 print_succ_bbs (file, bb);
4547 fprintf (file, "})\n");
4549 /* Print the basic_block's body. */
4550 fprintf (file, "%s {\n", s_indent);
4551 tree_dump_bb (bb, file, indent + 4);
4552 fprintf (file, "%s }\n", s_indent);
4555 print_loop (file, loop->inner, indent + 2);
4556 fprintf (file, "%s}\n", s_indent);
4557 print_loop (file, loop->next, indent);
4561 /* Follow a CFG edge from the entry point of the program, and on entry
4562 of a loop, pretty print the loop structure on FILE. */
4565 print_loop_ir (FILE *file)
4569 bb = BASIC_BLOCK (0);
4570 if (bb && bb->loop_father)
4571 print_loop (file, bb->loop_father, 0);
4575 /* Debugging loops structure at tree level. */
4578 debug_loop_ir (void)
4580 print_loop_ir (stderr);
4584 /* Return true if BB ends with a call, possibly followed by some
4585 instructions that must stay with the call. Return false,
4589 tree_block_ends_with_call_p (basic_block bb)
4591 block_stmt_iterator bsi = bsi_last (bb);
4592 return get_call_expr_in (bsi_stmt (bsi)) != NULL;
4596 /* Return true if BB ends with a conditional branch. Return false,
4600 tree_block_ends_with_condjump_p (basic_block bb)
4602 tree stmt = last_stmt (bb);
4603 return (stmt && TREE_CODE (stmt) == COND_EXPR);
4607 /* Return true if we need to add fake edge to exit at statement T.
4608 Helper function for tree_flow_call_edges_add. */
4611 need_fake_edge_p (tree t)
4615 /* NORETURN and LONGJMP calls already have an edge to exit.
4616 CONST and PURE calls do not need one.
4617 We don't currently check for CONST and PURE here, although
4618 it would be a good idea, because those attributes are
4619 figured out from the RTL in mark_constant_function, and
4620 the counter incrementation code from -fprofile-arcs
4621 leads to different results from -fbranch-probabilities. */
4622 call = get_call_expr_in (t);
4624 && !(call_expr_flags (call) & ECF_NORETURN))
4627 if (TREE_CODE (t) == ASM_EXPR
4628 && (ASM_VOLATILE_P (t) || ASM_INPUT_P (t)))
4635 /* Add fake edges to the function exit for any non constant and non
4636 noreturn calls, volatile inline assembly in the bitmap of blocks
4637 specified by BLOCKS or to the whole CFG if BLOCKS is zero. Return
4638 the number of blocks that were split.
4640 The goal is to expose cases in which entering a basic block does
4641 not imply that all subsequent instructions must be executed. */
4644 tree_flow_call_edges_add (sbitmap blocks)
4647 int blocks_split = 0;
4648 int last_bb = last_basic_block;
4649 bool check_last_block = false;
4651 if (n_basic_blocks == 0)
4655 check_last_block = true;
4657 check_last_block = TEST_BIT (blocks, EXIT_BLOCK_PTR->prev_bb->index);
4659 /* In the last basic block, before epilogue generation, there will be
4660 a fallthru edge to EXIT. Special care is required if the last insn
4661 of the last basic block is a call because make_edge folds duplicate
4662 edges, which would result in the fallthru edge also being marked
4663 fake, which would result in the fallthru edge being removed by
4664 remove_fake_edges, which would result in an invalid CFG.
4666 Moreover, we can't elide the outgoing fake edge, since the block
4667 profiler needs to take this into account in order to solve the minimal
4668 spanning tree in the case that the call doesn't return.
4670 Handle this by adding a dummy instruction in a new last basic block. */
4671 if (check_last_block)
4673 basic_block bb = EXIT_BLOCK_PTR->prev_bb;
4674 block_stmt_iterator bsi = bsi_last (bb);
4676 if (!bsi_end_p (bsi))
4679 if (need_fake_edge_p (t))
4683 e = find_edge (bb, EXIT_BLOCK_PTR);
4686 bsi_insert_on_edge (e, build_empty_stmt ());
4687 bsi_commit_edge_inserts ();
4692 /* Now add fake edges to the function exit for any non constant
4693 calls since there is no way that we can determine if they will
4695 for (i = 0; i < last_bb; i++)
4697 basic_block bb = BASIC_BLOCK (i);
4698 block_stmt_iterator bsi;
4699 tree stmt, last_stmt;
4704 if (blocks && !TEST_BIT (blocks, i))
4707 bsi = bsi_last (bb);
4708 if (!bsi_end_p (bsi))
4710 last_stmt = bsi_stmt (bsi);
4713 stmt = bsi_stmt (bsi);
4714 if (need_fake_edge_p (stmt))
4717 /* The handling above of the final block before the
4718 epilogue should be enough to verify that there is
4719 no edge to the exit block in CFG already.
4720 Calling make_edge in such case would cause us to
4721 mark that edge as fake and remove it later. */
4722 #ifdef ENABLE_CHECKING
4723 if (stmt == last_stmt)
4725 e = find_edge (bb, EXIT_BLOCK_PTR);
4726 gcc_assert (e == NULL);
4730 /* Note that the following may create a new basic block
4731 and renumber the existing basic blocks. */
4732 if (stmt != last_stmt)
4734 e = split_block (bb, stmt);
4738 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
4742 while (!bsi_end_p (bsi));
4747 verify_flow_info ();
4749 return blocks_split;
4753 tree_purge_dead_eh_edges (basic_block bb)
4755 bool changed = false;
4758 tree stmt = last_stmt (bb);
4760 if (stmt && tree_can_throw_internal (stmt))
4763 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
4765 if (e->flags & EDGE_EH)
4774 /* Removal of dead EH edges might change dominators of not
4775 just immediate successors. E.g. when bb1 is changed so that
4776 it no longer can throw and bb1->bb3 and bb1->bb4 are dead
4777 eh edges purged by this function in:
4789 idom(bb5) must be recomputed. For now just free the dominance
4792 free_dominance_info (CDI_DOMINATORS);
4798 tree_purge_all_dead_eh_edges (bitmap blocks)
4800 bool changed = false;
4804 EXECUTE_IF_SET_IN_BITMAP (blocks, 0, i, bi)
4806 changed |= tree_purge_dead_eh_edges (BASIC_BLOCK (i));
4812 /* This function is called whenever a new edge is created or
4816 tree_execute_on_growing_pred (edge e)
4818 basic_block bb = e->dest;
4821 reserve_phi_args_for_new_edge (bb);
4824 /* This function is called immediately before edge E is removed from
4825 the edge vector E->dest->preds. */
4828 tree_execute_on_shrinking_pred (edge e)
4830 if (phi_nodes (e->dest))
4831 remove_phi_args (e);
4834 /*---------------------------------------------------------------------------
4835 Helper functions for Loop versioning
4836 ---------------------------------------------------------------------------*/
4838 /* Adjust phi nodes for 'first' basic block. 'second' basic block is a copy
4839 of 'first'. Both of them are dominated by 'new_head' basic block. When
4840 'new_head' was created by 'second's incoming edge it received phi arguments
4841 on the edge by split_edge(). Later, additional edge 'e' was created to
4842 connect 'new_head' and 'first'. Now this routine adds phi args on this
4843 additional edge 'e' that new_head to second edge received as part of edge
4848 tree_lv_adjust_loop_header_phi (basic_block first, basic_block second,
4849 basic_block new_head, edge e)
4852 edge e2 = find_edge (new_head, second);
4854 /* Because NEW_HEAD has been created by splitting SECOND's incoming
4855 edge, we should always have an edge from NEW_HEAD to SECOND. */
4856 gcc_assert (e2 != NULL);
4858 /* Browse all 'second' basic block phi nodes and add phi args to
4859 edge 'e' for 'first' head. PHI args are always in correct order. */
4861 for (phi2 = phi_nodes (second), phi1 = phi_nodes (first);
4863 phi2 = PHI_CHAIN (phi2), phi1 = PHI_CHAIN (phi1))
4865 tree def = PHI_ARG_DEF (phi2, e2->dest_idx);
4866 add_phi_arg (phi1, def, e);
4870 /* Adds a if else statement to COND_BB with condition COND_EXPR.
4871 SECOND_HEAD is the destination of the THEN and FIRST_HEAD is
4872 the destination of the ELSE part. */
4874 tree_lv_add_condition_to_bb (basic_block first_head, basic_block second_head,
4875 basic_block cond_bb, void *cond_e)
4877 block_stmt_iterator bsi;
4878 tree goto1 = NULL_TREE;
4879 tree goto2 = NULL_TREE;
4880 tree new_cond_expr = NULL_TREE;
4881 tree cond_expr = (tree) cond_e;
4884 /* Build new conditional expr */
4885 goto1 = build1 (GOTO_EXPR, void_type_node, tree_block_label (first_head));
4886 goto2 = build1 (GOTO_EXPR, void_type_node, tree_block_label (second_head));
4887 new_cond_expr = build3 (COND_EXPR, void_type_node, cond_expr, goto1, goto2);
4889 /* Add new cond in cond_bb. */
4890 bsi = bsi_start (cond_bb);
4891 bsi_insert_after (&bsi, new_cond_expr, BSI_NEW_STMT);
4892 /* Adjust edges appropriately to connect new head with first head
4893 as well as second head. */
4894 e0 = single_succ_edge (cond_bb);
4895 e0->flags &= ~EDGE_FALLTHRU;
4896 e0->flags |= EDGE_FALSE_VALUE;
4899 struct cfg_hooks tree_cfg_hooks = {
4901 tree_verify_flow_info,
4902 tree_dump_bb, /* dump_bb */
4903 create_bb, /* create_basic_block */
4904 tree_redirect_edge_and_branch,/* redirect_edge_and_branch */
4905 tree_redirect_edge_and_branch_force,/* redirect_edge_and_branch_force */
4906 remove_bb, /* delete_basic_block */
4907 tree_split_block, /* split_block */
4908 tree_move_block_after, /* move_block_after */
4909 tree_can_merge_blocks_p, /* can_merge_blocks_p */
4910 tree_merge_blocks, /* merge_blocks */
4911 tree_predict_edge, /* predict_edge */
4912 tree_predicted_by_p, /* predicted_by_p */
4913 tree_can_duplicate_bb_p, /* can_duplicate_block_p */
4914 tree_duplicate_bb, /* duplicate_block */
4915 tree_split_edge, /* split_edge */
4916 tree_make_forwarder_block, /* make_forward_block */
4917 NULL, /* tidy_fallthru_edge */
4918 tree_block_ends_with_call_p, /* block_ends_with_call_p */
4919 tree_block_ends_with_condjump_p, /* block_ends_with_condjump_p */
4920 tree_flow_call_edges_add, /* flow_call_edges_add */
4921 tree_execute_on_growing_pred, /* execute_on_growing_pred */
4922 tree_execute_on_shrinking_pred, /* execute_on_shrinking_pred */
4923 tree_duplicate_loop_to_header_edge, /* duplicate loop for trees */
4924 tree_lv_add_condition_to_bb, /* lv_add_condition_to_bb */
4925 tree_lv_adjust_loop_header_phi, /* lv_adjust_loop_header_phi*/
4926 extract_true_false_edges_from_block, /* extract_cond_bb_edges */
4927 flush_pending_stmts /* flush_pending_stmts */
4931 /* Split all critical edges. */
4934 split_critical_edges (void)
4940 /* split_edge can redirect edges out of SWITCH_EXPRs, which can get
4941 expensive. So we want to enable recording of edge to CASE_LABEL_EXPR
4942 mappings around the calls to split_edge. */
4943 start_recording_case_labels ();
4946 FOR_EACH_EDGE (e, ei, bb->succs)
4947 if (EDGE_CRITICAL_P (e) && !(e->flags & EDGE_ABNORMAL))
4952 end_recording_case_labels ();
4955 struct tree_opt_pass pass_split_crit_edges =
4957 "crited", /* name */
4959 split_critical_edges, /* execute */
4962 0, /* static_pass_number */
4963 TV_TREE_SPLIT_EDGES, /* tv_id */
4964 PROP_cfg, /* properties required */
4965 PROP_no_crit_edges, /* properties_provided */
4966 0, /* properties_destroyed */
4967 0, /* todo_flags_start */
4968 TODO_dump_func, /* todo_flags_finish */
4973 /* Return EXP if it is a valid GIMPLE rvalue, else gimplify it into
4974 a temporary, make sure and register it to be renamed if necessary,
4975 and finally return the temporary. Put the statements to compute
4976 EXP before the current statement in BSI. */
4979 gimplify_val (block_stmt_iterator *bsi, tree type, tree exp)
4981 tree t, new_stmt, orig_stmt;
4983 if (is_gimple_val (exp))
4986 t = make_rename_temp (type, NULL);
4987 new_stmt = build (MODIFY_EXPR, type, t, exp);
4989 orig_stmt = bsi_stmt (*bsi);
4990 SET_EXPR_LOCUS (new_stmt, EXPR_LOCUS (orig_stmt));
4991 TREE_BLOCK (new_stmt) = TREE_BLOCK (orig_stmt);
4993 bsi_insert_before (bsi, new_stmt, BSI_SAME_STMT);
4998 /* Build a ternary operation and gimplify it. Emit code before BSI.
4999 Return the gimple_val holding the result. */
5002 gimplify_build3 (block_stmt_iterator *bsi, enum tree_code code,
5003 tree type, tree a, tree b, tree c)
5007 ret = fold_build3 (code, type, a, b, c);
5010 return gimplify_val (bsi, type, ret);
5013 /* Build a binary operation and gimplify it. Emit code before BSI.
5014 Return the gimple_val holding the result. */
5017 gimplify_build2 (block_stmt_iterator *bsi, enum tree_code code,
5018 tree type, tree a, tree b)
5022 ret = fold_build2 (code, type, a, b);
5025 return gimplify_val (bsi, type, ret);
5028 /* Build a unary operation and gimplify it. Emit code before BSI.
5029 Return the gimple_val holding the result. */
5032 gimplify_build1 (block_stmt_iterator *bsi, enum tree_code code, tree type,
5037 ret = fold_build1 (code, type, a);
5040 return gimplify_val (bsi, type, ret);
5045 /* Emit return warnings. */
5048 execute_warn_function_return (void)
5050 #ifdef USE_MAPPED_LOCATION
5051 source_location location;
5059 /* If we have a path to EXIT, then we do return. */
5060 if (TREE_THIS_VOLATILE (cfun->decl)
5061 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) > 0)
5063 #ifdef USE_MAPPED_LOCATION
5064 location = UNKNOWN_LOCATION;
5068 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
5070 last = last_stmt (e->src);
5071 if (TREE_CODE (last) == RETURN_EXPR
5072 #ifdef USE_MAPPED_LOCATION
5073 && (location = EXPR_LOCATION (last)) != UNKNOWN_LOCATION)
5075 && (locus = EXPR_LOCUS (last)) != NULL)
5079 #ifdef USE_MAPPED_LOCATION
5080 if (location == UNKNOWN_LOCATION)
5081 location = cfun->function_end_locus;
5082 warning (0, "%H%<noreturn%> function does return", &location);
5085 locus = &cfun->function_end_locus;
5086 warning (0, "%H%<noreturn%> function does return", locus);
5090 /* If we see "return;" in some basic block, then we do reach the end
5091 without returning a value. */
5092 else if (warn_return_type
5093 && !TREE_NO_WARNING (cfun->decl)
5094 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) > 0
5095 && !VOID_TYPE_P (TREE_TYPE (TREE_TYPE (cfun->decl))))
5097 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
5099 tree last = last_stmt (e->src);
5100 if (TREE_CODE (last) == RETURN_EXPR
5101 && TREE_OPERAND (last, 0) == NULL)
5103 #ifdef USE_MAPPED_LOCATION
5104 location = EXPR_LOCATION (last);
5105 if (location == UNKNOWN_LOCATION)
5106 location = cfun->function_end_locus;
5107 warning (0, "%Hcontrol reaches end of non-void function", &location);
5109 locus = EXPR_LOCUS (last);
5111 locus = &cfun->function_end_locus;
5112 warning (0, "%Hcontrol reaches end of non-void function", locus);
5114 TREE_NO_WARNING (cfun->decl) = 1;
5122 /* Given a basic block B which ends with a conditional and has
5123 precisely two successors, determine which of the edges is taken if
5124 the conditional is true and which is taken if the conditional is
5125 false. Set TRUE_EDGE and FALSE_EDGE appropriately. */
5128 extract_true_false_edges_from_block (basic_block b,
5132 edge e = EDGE_SUCC (b, 0);
5134 if (e->flags & EDGE_TRUE_VALUE)
5137 *false_edge = EDGE_SUCC (b, 1);
5142 *true_edge = EDGE_SUCC (b, 1);
5146 struct tree_opt_pass pass_warn_function_return =
5150 execute_warn_function_return, /* execute */
5153 0, /* static_pass_number */
5155 PROP_cfg, /* properties_required */
5156 0, /* properties_provided */
5157 0, /* properties_destroyed */
5158 0, /* todo_flags_start */
5159 0, /* todo_flags_finish */
5163 /* Emit noreturn warnings. */
5166 execute_warn_function_noreturn (void)
5168 if (warn_missing_noreturn
5169 && !TREE_THIS_VOLATILE (cfun->decl)
5170 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) == 0
5171 && !lang_hooks.function.missing_noreturn_ok_p (cfun->decl))
5172 warning (OPT_Wmissing_noreturn, "%Jfunction might be possible candidate "
5173 "for attribute %<noreturn%>",
5177 struct tree_opt_pass pass_warn_function_noreturn =
5181 execute_warn_function_noreturn, /* execute */
5184 0, /* static_pass_number */
5186 PROP_cfg, /* properties_required */
5187 0, /* properties_provided */
5188 0, /* properties_destroyed */
5189 0, /* todo_flags_start */
5190 0, /* todo_flags_finish */