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);
1240 replace_exp (use, val);
1242 if (TREE_CODE (stmt) == PHI_NODE)
1244 e = PHI_ARG_EDGE (stmt, PHI_ARG_INDEX_FROM_USE (use));
1245 if (e->flags & EDGE_ABNORMAL)
1247 /* This can only occur for virtual operands, since
1248 for the real ones SSA_NAME_OCCURS_IN_ABNORMAL_PHI (name))
1249 would prevent replacement. */
1250 gcc_assert (!is_gimple_reg (name));
1251 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (val) = 1;
1255 VEC_safe_push (tree, heap, stmts, stmt);
1258 /* We do not update the statements in the loop above. Consider
1261 If we performed the update in the first loop, the statement
1262 would be rescanned after first occurrence of w is replaced,
1263 the new uses would be placed to the beginning of the list,
1264 and we would never process them. */
1265 for (i = 0; VEC_iterate (tree, stmts, i, stmt); i++)
1269 fold_stmt_inplace (stmt);
1271 rhs = get_rhs (stmt);
1272 if (TREE_CODE (rhs) == ADDR_EXPR)
1273 recompute_tree_invarant_for_addr_expr (rhs);
1275 /* If the statement could throw and now cannot, we need to prune cfg. */
1276 if (maybe_clean_or_replace_eh_stmt (stmt, stmt))
1277 tree_purge_dead_eh_edges (bb_for_stmt (stmt));
1279 mark_new_vars_to_rename (stmt);
1282 VEC_free (tree, heap, stmts);
1284 /* Also update the trees stored in loop structures. */
1289 for (i = 0; i < current_loops->num; i++)
1291 loop = current_loops->parray[i];
1293 substitute_in_loop_info (loop, name, val);
1298 /* Merge block B into block A. */
1301 tree_merge_blocks (basic_block a, basic_block b)
1303 block_stmt_iterator bsi;
1304 tree_stmt_iterator last;
1308 fprintf (dump_file, "Merging blocks %d and %d\n", a->index, b->index);
1310 /* Remove all single-valued PHI nodes from block B of the form
1311 V_i = PHI <V_j> by propagating V_j to all the uses of V_i. */
1313 for (phi = phi_nodes (b); phi; phi = phi_nodes (b))
1315 tree def = PHI_RESULT (phi), use = PHI_ARG_DEF (phi, 0);
1318 if (!may_propagate_copy (def, use))
1320 gcc_assert (is_gimple_reg (def));
1322 /* Note that just emitting the copies is fine -- there is no problem
1323 with ordering of phi nodes. This is because A is the single
1324 predecessor of B, therefore results of the phi nodes cannot
1325 appear as arguments of the phi nodes. */
1326 copy = build2 (MODIFY_EXPR, void_type_node, def, use);
1327 bsi_insert_after (&bsi, copy, BSI_NEW_STMT);
1328 SET_PHI_RESULT (phi, NULL_TREE);
1329 SSA_NAME_DEF_STMT (def) = copy;
1332 replace_uses_by (def, use);
1334 remove_phi_node (phi, NULL);
1337 /* Ensure that B follows A. */
1338 move_block_after (b, a);
1340 gcc_assert (single_succ_edge (a)->flags & EDGE_FALLTHRU);
1341 gcc_assert (!last_stmt (a) || !stmt_ends_bb_p (last_stmt (a)));
1343 /* Remove labels from B and set bb_for_stmt to A for other statements. */
1344 for (bsi = bsi_start (b); !bsi_end_p (bsi);)
1346 if (TREE_CODE (bsi_stmt (bsi)) == LABEL_EXPR)
1348 tree label = bsi_stmt (bsi);
1351 /* Now that we can thread computed gotos, we might have
1352 a situation where we have a forced label in block B
1353 However, the label at the start of block B might still be
1354 used in other ways (think about the runtime checking for
1355 Fortran assigned gotos). So we can not just delete the
1356 label. Instead we move the label to the start of block A. */
1357 if (FORCED_LABEL (LABEL_EXPR_LABEL (label)))
1359 block_stmt_iterator dest_bsi = bsi_start (a);
1360 bsi_insert_before (&dest_bsi, label, BSI_NEW_STMT);
1365 set_bb_for_stmt (bsi_stmt (bsi), a);
1370 /* Merge the chains. */
1371 last = tsi_last (a->stmt_list);
1372 tsi_link_after (&last, b->stmt_list, TSI_NEW_STMT);
1373 b->stmt_list = NULL;
1377 /* Walk the function tree removing unnecessary statements.
1379 * Empty statement nodes are removed
1381 * Unnecessary TRY_FINALLY and TRY_CATCH blocks are removed
1383 * Unnecessary COND_EXPRs are removed
1385 * Some unnecessary BIND_EXPRs are removed
1387 Clearly more work could be done. The trick is doing the analysis
1388 and removal fast enough to be a net improvement in compile times.
1390 Note that when we remove a control structure such as a COND_EXPR
1391 BIND_EXPR, or TRY block, we will need to repeat this optimization pass
1392 to ensure we eliminate all the useless code. */
1403 static void remove_useless_stmts_1 (tree *, struct rus_data *);
1406 remove_useless_stmts_warn_notreached (tree stmt)
1408 if (EXPR_HAS_LOCATION (stmt))
1410 location_t loc = EXPR_LOCATION (stmt);
1411 if (LOCATION_LINE (loc) > 0)
1413 warning (0, "%Hwill never be executed", &loc);
1418 switch (TREE_CODE (stmt))
1420 case STATEMENT_LIST:
1422 tree_stmt_iterator i;
1423 for (i = tsi_start (stmt); !tsi_end_p (i); tsi_next (&i))
1424 if (remove_useless_stmts_warn_notreached (tsi_stmt (i)))
1430 if (remove_useless_stmts_warn_notreached (COND_EXPR_COND (stmt)))
1432 if (remove_useless_stmts_warn_notreached (COND_EXPR_THEN (stmt)))
1434 if (remove_useless_stmts_warn_notreached (COND_EXPR_ELSE (stmt)))
1438 case TRY_FINALLY_EXPR:
1439 case TRY_CATCH_EXPR:
1440 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt, 0)))
1442 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt, 1)))
1447 return remove_useless_stmts_warn_notreached (CATCH_BODY (stmt));
1448 case EH_FILTER_EXPR:
1449 return remove_useless_stmts_warn_notreached (EH_FILTER_FAILURE (stmt));
1451 return remove_useless_stmts_warn_notreached (BIND_EXPR_BLOCK (stmt));
1454 /* Not a live container. */
1462 remove_useless_stmts_cond (tree *stmt_p, struct rus_data *data)
1464 tree then_clause, else_clause, cond;
1465 bool save_has_label, then_has_label, else_has_label;
1467 save_has_label = data->has_label;
1468 data->has_label = false;
1469 data->last_goto = NULL;
1471 remove_useless_stmts_1 (&COND_EXPR_THEN (*stmt_p), data);
1473 then_has_label = data->has_label;
1474 data->has_label = false;
1475 data->last_goto = NULL;
1477 remove_useless_stmts_1 (&COND_EXPR_ELSE (*stmt_p), data);
1479 else_has_label = data->has_label;
1480 data->has_label = save_has_label | then_has_label | else_has_label;
1482 then_clause = COND_EXPR_THEN (*stmt_p);
1483 else_clause = COND_EXPR_ELSE (*stmt_p);
1484 cond = fold (COND_EXPR_COND (*stmt_p));
1486 /* If neither arm does anything at all, we can remove the whole IF. */
1487 if (!TREE_SIDE_EFFECTS (then_clause) && !TREE_SIDE_EFFECTS (else_clause))
1489 *stmt_p = build_empty_stmt ();
1490 data->repeat = true;
1493 /* If there are no reachable statements in an arm, then we can
1494 zap the entire conditional. */
1495 else if (integer_nonzerop (cond) && !else_has_label)
1497 if (warn_notreached)
1498 remove_useless_stmts_warn_notreached (else_clause);
1499 *stmt_p = then_clause;
1500 data->repeat = true;
1502 else if (integer_zerop (cond) && !then_has_label)
1504 if (warn_notreached)
1505 remove_useless_stmts_warn_notreached (then_clause);
1506 *stmt_p = else_clause;
1507 data->repeat = true;
1510 /* Check a couple of simple things on then/else with single stmts. */
1513 tree then_stmt = expr_only (then_clause);
1514 tree else_stmt = expr_only (else_clause);
1516 /* Notice branches to a common destination. */
1517 if (then_stmt && else_stmt
1518 && TREE_CODE (then_stmt) == GOTO_EXPR
1519 && TREE_CODE (else_stmt) == GOTO_EXPR
1520 && (GOTO_DESTINATION (then_stmt) == GOTO_DESTINATION (else_stmt)))
1522 *stmt_p = then_stmt;
1523 data->repeat = true;
1526 /* If the THEN/ELSE clause merely assigns a value to a variable or
1527 parameter which is already known to contain that value, then
1528 remove the useless THEN/ELSE clause. */
1529 else if (TREE_CODE (cond) == VAR_DECL || TREE_CODE (cond) == PARM_DECL)
1532 && TREE_CODE (else_stmt) == MODIFY_EXPR
1533 && TREE_OPERAND (else_stmt, 0) == cond
1534 && integer_zerop (TREE_OPERAND (else_stmt, 1)))
1535 COND_EXPR_ELSE (*stmt_p) = alloc_stmt_list ();
1537 else if ((TREE_CODE (cond) == EQ_EXPR || TREE_CODE (cond) == NE_EXPR)
1538 && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL
1539 || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL)
1540 && TREE_CONSTANT (TREE_OPERAND (cond, 1)))
1542 tree stmt = (TREE_CODE (cond) == EQ_EXPR
1543 ? then_stmt : else_stmt);
1544 tree *location = (TREE_CODE (cond) == EQ_EXPR
1545 ? &COND_EXPR_THEN (*stmt_p)
1546 : &COND_EXPR_ELSE (*stmt_p));
1549 && TREE_CODE (stmt) == MODIFY_EXPR
1550 && TREE_OPERAND (stmt, 0) == TREE_OPERAND (cond, 0)
1551 && TREE_OPERAND (stmt, 1) == TREE_OPERAND (cond, 1))
1552 *location = alloc_stmt_list ();
1556 /* Protect GOTOs in the arm of COND_EXPRs from being removed. They
1557 would be re-introduced during lowering. */
1558 data->last_goto = NULL;
1563 remove_useless_stmts_tf (tree *stmt_p, struct rus_data *data)
1565 bool save_may_branch, save_may_throw;
1566 bool this_may_branch, this_may_throw;
1568 /* Collect may_branch and may_throw information for the body only. */
1569 save_may_branch = data->may_branch;
1570 save_may_throw = data->may_throw;
1571 data->may_branch = false;
1572 data->may_throw = false;
1573 data->last_goto = NULL;
1575 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 0), data);
1577 this_may_branch = data->may_branch;
1578 this_may_throw = data->may_throw;
1579 data->may_branch |= save_may_branch;
1580 data->may_throw |= save_may_throw;
1581 data->last_goto = NULL;
1583 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 1), data);
1585 /* If the body is empty, then we can emit the FINALLY block without
1586 the enclosing TRY_FINALLY_EXPR. */
1587 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 0)))
1589 *stmt_p = TREE_OPERAND (*stmt_p, 1);
1590 data->repeat = true;
1593 /* If the handler is empty, then we can emit the TRY block without
1594 the enclosing TRY_FINALLY_EXPR. */
1595 else if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 1)))
1597 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1598 data->repeat = true;
1601 /* If the body neither throws, nor branches, then we can safely
1602 string the TRY and FINALLY blocks together. */
1603 else if (!this_may_branch && !this_may_throw)
1605 tree stmt = *stmt_p;
1606 *stmt_p = TREE_OPERAND (stmt, 0);
1607 append_to_statement_list (TREE_OPERAND (stmt, 1), stmt_p);
1608 data->repeat = true;
1614 remove_useless_stmts_tc (tree *stmt_p, struct rus_data *data)
1616 bool save_may_throw, this_may_throw;
1617 tree_stmt_iterator i;
1620 /* Collect may_throw information for the body only. */
1621 save_may_throw = data->may_throw;
1622 data->may_throw = false;
1623 data->last_goto = NULL;
1625 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 0), data);
1627 this_may_throw = data->may_throw;
1628 data->may_throw = save_may_throw;
1630 /* If the body cannot throw, then we can drop the entire TRY_CATCH_EXPR. */
1631 if (!this_may_throw)
1633 if (warn_notreached)
1634 remove_useless_stmts_warn_notreached (TREE_OPERAND (*stmt_p, 1));
1635 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1636 data->repeat = true;
1640 /* Process the catch clause specially. We may be able to tell that
1641 no exceptions propagate past this point. */
1643 this_may_throw = true;
1644 i = tsi_start (TREE_OPERAND (*stmt_p, 1));
1645 stmt = tsi_stmt (i);
1646 data->last_goto = NULL;
1648 switch (TREE_CODE (stmt))
1651 for (; !tsi_end_p (i); tsi_next (&i))
1653 stmt = tsi_stmt (i);
1654 /* If we catch all exceptions, then the body does not
1655 propagate exceptions past this point. */
1656 if (CATCH_TYPES (stmt) == NULL)
1657 this_may_throw = false;
1658 data->last_goto = NULL;
1659 remove_useless_stmts_1 (&CATCH_BODY (stmt), data);
1663 case EH_FILTER_EXPR:
1664 if (EH_FILTER_MUST_NOT_THROW (stmt))
1665 this_may_throw = false;
1666 else if (EH_FILTER_TYPES (stmt) == NULL)
1667 this_may_throw = false;
1668 remove_useless_stmts_1 (&EH_FILTER_FAILURE (stmt), data);
1672 /* Otherwise this is a cleanup. */
1673 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 1), data);
1675 /* If the cleanup is empty, then we can emit the TRY block without
1676 the enclosing TRY_CATCH_EXPR. */
1677 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 1)))
1679 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1680 data->repeat = true;
1684 data->may_throw |= this_may_throw;
1689 remove_useless_stmts_bind (tree *stmt_p, struct rus_data *data)
1693 /* First remove anything underneath the BIND_EXPR. */
1694 remove_useless_stmts_1 (&BIND_EXPR_BODY (*stmt_p), data);
1696 /* If the BIND_EXPR has no variables, then we can pull everything
1697 up one level and remove the BIND_EXPR, unless this is the toplevel
1698 BIND_EXPR for the current function or an inlined function.
1700 When this situation occurs we will want to apply this
1701 optimization again. */
1702 block = BIND_EXPR_BLOCK (*stmt_p);
1703 if (BIND_EXPR_VARS (*stmt_p) == NULL_TREE
1704 && *stmt_p != DECL_SAVED_TREE (current_function_decl)
1706 || ! BLOCK_ABSTRACT_ORIGIN (block)
1707 || (TREE_CODE (BLOCK_ABSTRACT_ORIGIN (block))
1710 *stmt_p = BIND_EXPR_BODY (*stmt_p);
1711 data->repeat = true;
1717 remove_useless_stmts_goto (tree *stmt_p, struct rus_data *data)
1719 tree dest = GOTO_DESTINATION (*stmt_p);
1721 data->may_branch = true;
1722 data->last_goto = NULL;
1724 /* Record the last goto expr, so that we can delete it if unnecessary. */
1725 if (TREE_CODE (dest) == LABEL_DECL)
1726 data->last_goto = stmt_p;
1731 remove_useless_stmts_label (tree *stmt_p, struct rus_data *data)
1733 tree label = LABEL_EXPR_LABEL (*stmt_p);
1735 data->has_label = true;
1737 /* We do want to jump across non-local label receiver code. */
1738 if (DECL_NONLOCAL (label))
1739 data->last_goto = NULL;
1741 else if (data->last_goto && GOTO_DESTINATION (*data->last_goto) == label)
1743 *data->last_goto = build_empty_stmt ();
1744 data->repeat = true;
1747 /* ??? Add something here to delete unused labels. */
1751 /* If the function is "const" or "pure", then clear TREE_SIDE_EFFECTS on its
1752 decl. This allows us to eliminate redundant or useless
1753 calls to "const" functions.
1755 Gimplifier already does the same operation, but we may notice functions
1756 being const and pure once their calls has been gimplified, so we need
1757 to update the flag. */
1760 update_call_expr_flags (tree call)
1762 tree decl = get_callee_fndecl (call);
1765 if (call_expr_flags (call) & (ECF_CONST | ECF_PURE))
1766 TREE_SIDE_EFFECTS (call) = 0;
1767 if (TREE_NOTHROW (decl))
1768 TREE_NOTHROW (call) = 1;
1772 /* T is CALL_EXPR. Set current_function_calls_* flags. */
1775 notice_special_calls (tree t)
1777 int flags = call_expr_flags (t);
1779 if (flags & ECF_MAY_BE_ALLOCA)
1780 current_function_calls_alloca = true;
1781 if (flags & ECF_RETURNS_TWICE)
1782 current_function_calls_setjmp = true;
1786 /* Clear flags set by notice_special_calls. Used by dead code removal
1787 to update the flags. */
1790 clear_special_calls (void)
1792 current_function_calls_alloca = false;
1793 current_function_calls_setjmp = false;
1798 remove_useless_stmts_1 (tree *tp, struct rus_data *data)
1802 switch (TREE_CODE (t))
1805 remove_useless_stmts_cond (tp, data);
1808 case TRY_FINALLY_EXPR:
1809 remove_useless_stmts_tf (tp, data);
1812 case TRY_CATCH_EXPR:
1813 remove_useless_stmts_tc (tp, data);
1817 remove_useless_stmts_bind (tp, data);
1821 remove_useless_stmts_goto (tp, data);
1825 remove_useless_stmts_label (tp, data);
1830 data->last_goto = NULL;
1831 data->may_branch = true;
1836 data->last_goto = NULL;
1837 notice_special_calls (t);
1838 update_call_expr_flags (t);
1839 if (tree_could_throw_p (t))
1840 data->may_throw = true;
1844 data->last_goto = NULL;
1846 op = get_call_expr_in (t);
1849 update_call_expr_flags (op);
1850 notice_special_calls (op);
1852 if (tree_could_throw_p (t))
1853 data->may_throw = true;
1856 case STATEMENT_LIST:
1858 tree_stmt_iterator i = tsi_start (t);
1859 while (!tsi_end_p (i))
1862 if (IS_EMPTY_STMT (t))
1868 remove_useless_stmts_1 (tsi_stmt_ptr (i), data);
1871 if (TREE_CODE (t) == STATEMENT_LIST)
1873 tsi_link_before (&i, t, TSI_SAME_STMT);
1883 data->last_goto = NULL;
1887 data->last_goto = NULL;
1893 remove_useless_stmts (void)
1895 struct rus_data data;
1897 clear_special_calls ();
1901 memset (&data, 0, sizeof (data));
1902 remove_useless_stmts_1 (&DECL_SAVED_TREE (current_function_decl), &data);
1904 while (data.repeat);
1908 struct tree_opt_pass pass_remove_useless_stmts =
1910 "useless", /* name */
1912 remove_useless_stmts, /* execute */
1915 0, /* static_pass_number */
1917 PROP_gimple_any, /* properties_required */
1918 0, /* properties_provided */
1919 0, /* properties_destroyed */
1920 0, /* todo_flags_start */
1921 TODO_dump_func, /* todo_flags_finish */
1925 /* Remove PHI nodes associated with basic block BB and all edges out of BB. */
1928 remove_phi_nodes_and_edges_for_unreachable_block (basic_block bb)
1932 /* Since this block is no longer reachable, we can just delete all
1933 of its PHI nodes. */
1934 phi = phi_nodes (bb);
1937 tree next = PHI_CHAIN (phi);
1938 remove_phi_node (phi, NULL_TREE);
1942 /* Remove edges to BB's successors. */
1943 while (EDGE_COUNT (bb->succs) > 0)
1944 remove_edge (EDGE_SUCC (bb, 0));
1948 /* Remove statements of basic block BB. */
1951 remove_bb (basic_block bb)
1953 block_stmt_iterator i;
1954 #ifdef USE_MAPPED_LOCATION
1955 source_location loc = UNKNOWN_LOCATION;
1957 source_locus loc = 0;
1962 fprintf (dump_file, "Removing basic block %d\n", bb->index);
1963 if (dump_flags & TDF_DETAILS)
1965 dump_bb (bb, dump_file, 0);
1966 fprintf (dump_file, "\n");
1970 /* If we remove the header or the latch of a loop, mark the loop for
1971 removal by setting its header and latch to NULL. */
1974 struct loop *loop = bb->loop_father;
1976 if (loop->latch == bb
1977 || loop->header == bb)
1980 loop->header = NULL;
1984 /* Remove all the instructions in the block. */
1985 for (i = bsi_start (bb); !bsi_end_p (i);)
1987 tree stmt = bsi_stmt (i);
1988 if (TREE_CODE (stmt) == LABEL_EXPR
1989 && (FORCED_LABEL (LABEL_EXPR_LABEL (stmt))
1990 || DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt))))
1993 block_stmt_iterator new_bsi;
1995 /* A non-reachable non-local label may still be referenced.
1996 But it no longer needs to carry the extra semantics of
1998 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)))
2000 DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)) = 0;
2001 FORCED_LABEL (LABEL_EXPR_LABEL (stmt)) = 1;
2004 new_bb = bb->prev_bb;
2005 new_bsi = bsi_start (new_bb);
2007 bsi_insert_before (&new_bsi, stmt, BSI_NEW_STMT);
2011 /* Release SSA definitions if we are in SSA. Note that we
2012 may be called when not in SSA. For example,
2013 final_cleanup calls this function via
2014 cleanup_tree_cfg. */
2016 release_defs (stmt);
2021 /* Don't warn for removed gotos. Gotos are often removed due to
2022 jump threading, thus resulting in bogus warnings. Not great,
2023 since this way we lose warnings for gotos in the original
2024 program that are indeed unreachable. */
2025 if (TREE_CODE (stmt) != GOTO_EXPR && EXPR_HAS_LOCATION (stmt) && !loc)
2027 #ifdef USE_MAPPED_LOCATION
2028 if (EXPR_HAS_LOCATION (stmt))
2029 loc = EXPR_LOCATION (stmt);
2032 t = EXPR_LOCUS (stmt);
2033 if (t && LOCATION_LINE (*t) > 0)
2039 /* If requested, give a warning that the first statement in the
2040 block is unreachable. We walk statements backwards in the
2041 loop above, so the last statement we process is the first statement
2043 #ifdef USE_MAPPED_LOCATION
2044 if (loc > BUILTINS_LOCATION)
2045 warning (OPT_Wunreachable_code, "%Hwill never be executed", &loc);
2048 warning (OPT_Wunreachable_code, "%Hwill never be executed", loc);
2051 remove_phi_nodes_and_edges_for_unreachable_block (bb);
2055 /* Given a basic block BB ending with COND_EXPR or SWITCH_EXPR, and a
2056 predicate VAL, return the edge that will be taken out of the block.
2057 If VAL does not match a unique edge, NULL is returned. */
2060 find_taken_edge (basic_block bb, tree val)
2064 stmt = last_stmt (bb);
2067 gcc_assert (is_ctrl_stmt (stmt));
2070 if (! is_gimple_min_invariant (val))
2073 if (TREE_CODE (stmt) == COND_EXPR)
2074 return find_taken_edge_cond_expr (bb, val);
2076 if (TREE_CODE (stmt) == SWITCH_EXPR)
2077 return find_taken_edge_switch_expr (bb, val);
2079 if (computed_goto_p (stmt))
2080 return find_taken_edge_computed_goto (bb, TREE_OPERAND( val, 0));
2085 /* Given a constant value VAL and the entry block BB to a GOTO_EXPR
2086 statement, determine which of the outgoing edges will be taken out of the
2087 block. Return NULL if either edge may be taken. */
2090 find_taken_edge_computed_goto (basic_block bb, tree val)
2095 dest = label_to_block (val);
2098 e = find_edge (bb, dest);
2099 gcc_assert (e != NULL);
2105 /* Given a constant value VAL and the entry block BB to a COND_EXPR
2106 statement, determine which of the two edges will be taken out of the
2107 block. Return NULL if either edge may be taken. */
2110 find_taken_edge_cond_expr (basic_block bb, tree val)
2112 edge true_edge, false_edge;
2114 extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
2116 gcc_assert (TREE_CODE (val) == INTEGER_CST);
2117 return (zero_p (val) ? false_edge : true_edge);
2120 /* Given an INTEGER_CST VAL and the entry block BB to a SWITCH_EXPR
2121 statement, determine which edge will be taken out of the block. Return
2122 NULL if any edge may be taken. */
2125 find_taken_edge_switch_expr (basic_block bb, tree val)
2127 tree switch_expr, taken_case;
2128 basic_block dest_bb;
2131 switch_expr = last_stmt (bb);
2132 taken_case = find_case_label_for_value (switch_expr, val);
2133 dest_bb = label_to_block (CASE_LABEL (taken_case));
2135 e = find_edge (bb, dest_bb);
2141 /* Return the CASE_LABEL_EXPR that SWITCH_EXPR will take for VAL.
2142 We can make optimal use here of the fact that the case labels are
2143 sorted: We can do a binary search for a case matching VAL. */
2146 find_case_label_for_value (tree switch_expr, tree val)
2148 tree vec = SWITCH_LABELS (switch_expr);
2149 size_t low, high, n = TREE_VEC_LENGTH (vec);
2150 tree default_case = TREE_VEC_ELT (vec, n - 1);
2152 for (low = -1, high = n - 1; high - low > 1; )
2154 size_t i = (high + low) / 2;
2155 tree t = TREE_VEC_ELT (vec, i);
2158 /* Cache the result of comparing CASE_LOW and val. */
2159 cmp = tree_int_cst_compare (CASE_LOW (t), val);
2166 if (CASE_HIGH (t) == NULL)
2168 /* A singe-valued case label. */
2174 /* A case range. We can only handle integer ranges. */
2175 if (cmp <= 0 && tree_int_cst_compare (CASE_HIGH (t), val) >= 0)
2180 return default_case;
2186 /*---------------------------------------------------------------------------
2188 ---------------------------------------------------------------------------*/
2190 /* Dump tree-specific information of block BB to file OUTF. */
2193 tree_dump_bb (basic_block bb, FILE *outf, int indent)
2195 dump_generic_bb (outf, bb, indent, TDF_VOPS);
2199 /* Dump a basic block on stderr. */
2202 debug_tree_bb (basic_block bb)
2204 dump_bb (bb, stderr, 0);
2208 /* Dump basic block with index N on stderr. */
2211 debug_tree_bb_n (int n)
2213 debug_tree_bb (BASIC_BLOCK (n));
2214 return BASIC_BLOCK (n);
2218 /* Dump the CFG on stderr.
2220 FLAGS are the same used by the tree dumping functions
2221 (see TDF_* in tree.h). */
2224 debug_tree_cfg (int flags)
2226 dump_tree_cfg (stderr, flags);
2230 /* Dump the program showing basic block boundaries on the given FILE.
2232 FLAGS are the same used by the tree dumping functions (see TDF_* in
2236 dump_tree_cfg (FILE *file, int flags)
2238 if (flags & TDF_DETAILS)
2240 const char *funcname
2241 = lang_hooks.decl_printable_name (current_function_decl, 2);
2244 fprintf (file, ";; Function %s\n\n", funcname);
2245 fprintf (file, ";; \n%d basic blocks, %d edges, last basic block %d.\n\n",
2246 n_basic_blocks, n_edges, last_basic_block);
2248 brief_dump_cfg (file);
2249 fprintf (file, "\n");
2252 if (flags & TDF_STATS)
2253 dump_cfg_stats (file);
2255 dump_function_to_file (current_function_decl, file, flags | TDF_BLOCKS);
2259 /* Dump CFG statistics on FILE. */
2262 dump_cfg_stats (FILE *file)
2264 static long max_num_merged_labels = 0;
2265 unsigned long size, total = 0;
2268 const char * const fmt_str = "%-30s%-13s%12s\n";
2269 const char * const fmt_str_1 = "%-30s%13d%11lu%c\n";
2270 const char * const fmt_str_2 = "%-30s%13ld%11lu%c\n";
2271 const char * const fmt_str_3 = "%-43s%11lu%c\n";
2272 const char *funcname
2273 = lang_hooks.decl_printable_name (current_function_decl, 2);
2276 fprintf (file, "\nCFG Statistics for %s\n\n", funcname);
2278 fprintf (file, "---------------------------------------------------------\n");
2279 fprintf (file, fmt_str, "", " Number of ", "Memory");
2280 fprintf (file, fmt_str, "", " instances ", "used ");
2281 fprintf (file, "---------------------------------------------------------\n");
2283 size = n_basic_blocks * sizeof (struct basic_block_def);
2285 fprintf (file, fmt_str_1, "Basic blocks", n_basic_blocks,
2286 SCALE (size), LABEL (size));
2290 num_edges += EDGE_COUNT (bb->succs);
2291 size = num_edges * sizeof (struct edge_def);
2293 fprintf (file, fmt_str_2, "Edges", num_edges, SCALE (size), LABEL (size));
2295 fprintf (file, "---------------------------------------------------------\n");
2296 fprintf (file, fmt_str_3, "Total memory used by CFG data", SCALE (total),
2298 fprintf (file, "---------------------------------------------------------\n");
2299 fprintf (file, "\n");
2301 if (cfg_stats.num_merged_labels > max_num_merged_labels)
2302 max_num_merged_labels = cfg_stats.num_merged_labels;
2304 fprintf (file, "Coalesced label blocks: %ld (Max so far: %ld)\n",
2305 cfg_stats.num_merged_labels, max_num_merged_labels);
2307 fprintf (file, "\n");
2311 /* Dump CFG statistics on stderr. Keep extern so that it's always
2312 linked in the final executable. */
2315 debug_cfg_stats (void)
2317 dump_cfg_stats (stderr);
2321 /* Dump the flowgraph to a .vcg FILE. */
2324 tree_cfg2vcg (FILE *file)
2329 const char *funcname
2330 = lang_hooks.decl_printable_name (current_function_decl, 2);
2332 /* Write the file header. */
2333 fprintf (file, "graph: { title: \"%s\"\n", funcname);
2334 fprintf (file, "node: { title: \"ENTRY\" label: \"ENTRY\" }\n");
2335 fprintf (file, "node: { title: \"EXIT\" label: \"EXIT\" }\n");
2337 /* Write blocks and edges. */
2338 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
2340 fprintf (file, "edge: { sourcename: \"ENTRY\" targetname: \"%d\"",
2343 if (e->flags & EDGE_FAKE)
2344 fprintf (file, " linestyle: dotted priority: 10");
2346 fprintf (file, " linestyle: solid priority: 100");
2348 fprintf (file, " }\n");
2354 enum tree_code head_code, end_code;
2355 const char *head_name, *end_name;
2358 tree first = first_stmt (bb);
2359 tree last = last_stmt (bb);
2363 head_code = TREE_CODE (first);
2364 head_name = tree_code_name[head_code];
2365 head_line = get_lineno (first);
2368 head_name = "no-statement";
2372 end_code = TREE_CODE (last);
2373 end_name = tree_code_name[end_code];
2374 end_line = get_lineno (last);
2377 end_name = "no-statement";
2379 fprintf (file, "node: { title: \"%d\" label: \"#%d\\n%s (%d)\\n%s (%d)\"}\n",
2380 bb->index, bb->index, head_name, head_line, end_name,
2383 FOR_EACH_EDGE (e, ei, bb->succs)
2385 if (e->dest == EXIT_BLOCK_PTR)
2386 fprintf (file, "edge: { sourcename: \"%d\" targetname: \"EXIT\"", bb->index);
2388 fprintf (file, "edge: { sourcename: \"%d\" targetname: \"%d\"", bb->index, e->dest->index);
2390 if (e->flags & EDGE_FAKE)
2391 fprintf (file, " priority: 10 linestyle: dotted");
2393 fprintf (file, " priority: 100 linestyle: solid");
2395 fprintf (file, " }\n");
2398 if (bb->next_bb != EXIT_BLOCK_PTR)
2402 fputs ("}\n\n", file);
2407 /*---------------------------------------------------------------------------
2408 Miscellaneous helpers
2409 ---------------------------------------------------------------------------*/
2411 /* Return true if T represents a stmt that always transfers control. */
2414 is_ctrl_stmt (tree t)
2416 return (TREE_CODE (t) == COND_EXPR
2417 || TREE_CODE (t) == SWITCH_EXPR
2418 || TREE_CODE (t) == GOTO_EXPR
2419 || TREE_CODE (t) == RETURN_EXPR
2420 || TREE_CODE (t) == RESX_EXPR);
2424 /* Return true if T is a statement that may alter the flow of control
2425 (e.g., a call to a non-returning function). */
2428 is_ctrl_altering_stmt (tree t)
2433 call = get_call_expr_in (t);
2436 /* A non-pure/const CALL_EXPR alters flow control if the current
2437 function has nonlocal labels. */
2438 if (TREE_SIDE_EFFECTS (call) && current_function_has_nonlocal_label)
2441 /* A CALL_EXPR also alters control flow if it does not return. */
2442 if (call_expr_flags (call) & ECF_NORETURN)
2446 /* If a statement can throw, it alters control flow. */
2447 return tree_can_throw_internal (t);
2451 /* Return true if T is a computed goto. */
2454 computed_goto_p (tree t)
2456 return (TREE_CODE (t) == GOTO_EXPR
2457 && TREE_CODE (GOTO_DESTINATION (t)) != LABEL_DECL);
2461 /* Checks whether EXPR is a simple local goto. */
2464 simple_goto_p (tree expr)
2466 return (TREE_CODE (expr) == GOTO_EXPR
2467 && TREE_CODE (GOTO_DESTINATION (expr)) == LABEL_DECL);
2471 /* Return true if T should start a new basic block. PREV_T is the
2472 statement preceding T. It is used when T is a label or a case label.
2473 Labels should only start a new basic block if their previous statement
2474 wasn't a label. Otherwise, sequence of labels would generate
2475 unnecessary basic blocks that only contain a single label. */
2478 stmt_starts_bb_p (tree t, tree prev_t)
2483 /* LABEL_EXPRs start a new basic block only if the preceding
2484 statement wasn't a label of the same type. This prevents the
2485 creation of consecutive blocks that have nothing but a single
2487 if (TREE_CODE (t) == LABEL_EXPR)
2489 /* Nonlocal and computed GOTO targets always start a new block. */
2490 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (t))
2491 || FORCED_LABEL (LABEL_EXPR_LABEL (t)))
2494 if (prev_t && TREE_CODE (prev_t) == LABEL_EXPR)
2496 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (prev_t)))
2499 cfg_stats.num_merged_labels++;
2510 /* Return true if T should end a basic block. */
2513 stmt_ends_bb_p (tree t)
2515 return is_ctrl_stmt (t) || is_ctrl_altering_stmt (t);
2519 /* Add gotos that used to be represented implicitly in the CFG. */
2522 disband_implicit_edges (void)
2525 block_stmt_iterator last;
2532 last = bsi_last (bb);
2533 stmt = last_stmt (bb);
2535 if (stmt && TREE_CODE (stmt) == COND_EXPR)
2537 /* Remove superfluous gotos from COND_EXPR branches. Moved
2538 from cfg_remove_useless_stmts here since it violates the
2539 invariants for tree--cfg correspondence and thus fits better
2540 here where we do it anyway. */
2541 e = find_edge (bb, bb->next_bb);
2544 if (e->flags & EDGE_TRUE_VALUE)
2545 COND_EXPR_THEN (stmt) = build_empty_stmt ();
2546 else if (e->flags & EDGE_FALSE_VALUE)
2547 COND_EXPR_ELSE (stmt) = build_empty_stmt ();
2550 e->flags |= EDGE_FALLTHRU;
2556 if (stmt && TREE_CODE (stmt) == RETURN_EXPR)
2558 /* Remove the RETURN_EXPR if we may fall though to the exit
2560 gcc_assert (single_succ_p (bb));
2561 gcc_assert (single_succ (bb) == EXIT_BLOCK_PTR);
2563 if (bb->next_bb == EXIT_BLOCK_PTR
2564 && !TREE_OPERAND (stmt, 0))
2567 single_succ_edge (bb)->flags |= EDGE_FALLTHRU;
2572 /* There can be no fallthru edge if the last statement is a control
2574 if (stmt && is_ctrl_stmt (stmt))
2577 /* Find a fallthru edge and emit the goto if necessary. */
2578 FOR_EACH_EDGE (e, ei, bb->succs)
2579 if (e->flags & EDGE_FALLTHRU)
2582 if (!e || e->dest == bb->next_bb)
2585 gcc_assert (e->dest != EXIT_BLOCK_PTR);
2586 label = tree_block_label (e->dest);
2588 stmt = build1 (GOTO_EXPR, void_type_node, label);
2589 #ifdef USE_MAPPED_LOCATION
2590 SET_EXPR_LOCATION (stmt, e->goto_locus);
2592 SET_EXPR_LOCUS (stmt, e->goto_locus);
2594 bsi_insert_after (&last, stmt, BSI_NEW_STMT);
2595 e->flags &= ~EDGE_FALLTHRU;
2599 /* Remove block annotations and other datastructures. */
2602 delete_tree_cfg_annotations (void)
2604 label_to_block_map = NULL;
2608 /* Return the first statement in basic block BB. */
2611 first_stmt (basic_block bb)
2613 block_stmt_iterator i = bsi_start (bb);
2614 return !bsi_end_p (i) ? bsi_stmt (i) : NULL_TREE;
2618 /* Return the last statement in basic block BB. */
2621 last_stmt (basic_block bb)
2623 block_stmt_iterator b = bsi_last (bb);
2624 return !bsi_end_p (b) ? bsi_stmt (b) : NULL_TREE;
2628 /* Return a pointer to the last statement in block BB. */
2631 last_stmt_ptr (basic_block bb)
2633 block_stmt_iterator last = bsi_last (bb);
2634 return !bsi_end_p (last) ? bsi_stmt_ptr (last) : NULL;
2638 /* Return the last statement of an otherwise empty block. Return NULL
2639 if the block is totally empty, or if it contains more than one
2643 last_and_only_stmt (basic_block bb)
2645 block_stmt_iterator i = bsi_last (bb);
2651 last = bsi_stmt (i);
2656 /* Empty statements should no longer appear in the instruction stream.
2657 Everything that might have appeared before should be deleted by
2658 remove_useless_stmts, and the optimizers should just bsi_remove
2659 instead of smashing with build_empty_stmt.
2661 Thus the only thing that should appear here in a block containing
2662 one executable statement is a label. */
2663 prev = bsi_stmt (i);
2664 if (TREE_CODE (prev) == LABEL_EXPR)
2671 /* Mark BB as the basic block holding statement T. */
2674 set_bb_for_stmt (tree t, basic_block bb)
2676 if (TREE_CODE (t) == PHI_NODE)
2678 else if (TREE_CODE (t) == STATEMENT_LIST)
2680 tree_stmt_iterator i;
2681 for (i = tsi_start (t); !tsi_end_p (i); tsi_next (&i))
2682 set_bb_for_stmt (tsi_stmt (i), bb);
2686 stmt_ann_t ann = get_stmt_ann (t);
2689 /* If the statement is a label, add the label to block-to-labels map
2690 so that we can speed up edge creation for GOTO_EXPRs. */
2691 if (TREE_CODE (t) == LABEL_EXPR)
2695 t = LABEL_EXPR_LABEL (t);
2696 uid = LABEL_DECL_UID (t);
2699 LABEL_DECL_UID (t) = uid = cfun->last_label_uid++;
2700 if (VARRAY_SIZE (label_to_block_map) <= (unsigned) uid)
2701 VARRAY_GROW (label_to_block_map, 3 * uid / 2);
2704 /* We're moving an existing label. Make sure that we've
2705 removed it from the old block. */
2706 gcc_assert (!bb || !VARRAY_BB (label_to_block_map, uid));
2707 VARRAY_BB (label_to_block_map, uid) = bb;
2712 /* Finds iterator for STMT. */
2714 extern block_stmt_iterator
2715 bsi_for_stmt (tree stmt)
2717 block_stmt_iterator bsi;
2719 for (bsi = bsi_start (bb_for_stmt (stmt)); !bsi_end_p (bsi); bsi_next (&bsi))
2720 if (bsi_stmt (bsi) == stmt)
2726 /* Mark statement T as modified, and update it. */
2728 update_modified_stmts (tree t)
2730 if (TREE_CODE (t) == STATEMENT_LIST)
2732 tree_stmt_iterator i;
2734 for (i = tsi_start (t); !tsi_end_p (i); tsi_next (&i))
2736 stmt = tsi_stmt (i);
2737 update_stmt_if_modified (stmt);
2741 update_stmt_if_modified (t);
2744 /* Insert statement (or statement list) T before the statement
2745 pointed-to by iterator I. M specifies how to update iterator I
2746 after insertion (see enum bsi_iterator_update). */
2749 bsi_insert_before (block_stmt_iterator *i, tree t, enum bsi_iterator_update m)
2751 set_bb_for_stmt (t, i->bb);
2752 update_modified_stmts (t);
2753 tsi_link_before (&i->tsi, t, m);
2757 /* Insert statement (or statement list) T after the statement
2758 pointed-to by iterator I. M specifies how to update iterator I
2759 after insertion (see enum bsi_iterator_update). */
2762 bsi_insert_after (block_stmt_iterator *i, tree t, enum bsi_iterator_update m)
2764 set_bb_for_stmt (t, i->bb);
2765 update_modified_stmts (t);
2766 tsi_link_after (&i->tsi, t, m);
2770 /* Remove the statement pointed to by iterator I. The iterator is updated
2771 to the next statement. */
2774 bsi_remove (block_stmt_iterator *i)
2776 tree t = bsi_stmt (*i);
2777 set_bb_for_stmt (t, NULL);
2778 delink_stmt_imm_use (t);
2779 tsi_delink (&i->tsi);
2780 mark_stmt_modified (t);
2784 /* Move the statement at FROM so it comes right after the statement at TO. */
2787 bsi_move_after (block_stmt_iterator *from, block_stmt_iterator *to)
2789 tree stmt = bsi_stmt (*from);
2791 bsi_insert_after (to, stmt, BSI_SAME_STMT);
2795 /* Move the statement at FROM so it comes right before the statement at TO. */
2798 bsi_move_before (block_stmt_iterator *from, block_stmt_iterator *to)
2800 tree stmt = bsi_stmt (*from);
2802 bsi_insert_before (to, stmt, BSI_SAME_STMT);
2806 /* Move the statement at FROM to the end of basic block BB. */
2809 bsi_move_to_bb_end (block_stmt_iterator *from, basic_block bb)
2811 block_stmt_iterator last = bsi_last (bb);
2813 /* Have to check bsi_end_p because it could be an empty block. */
2814 if (!bsi_end_p (last) && is_ctrl_stmt (bsi_stmt (last)))
2815 bsi_move_before (from, &last);
2817 bsi_move_after (from, &last);
2821 /* Replace the contents of the statement pointed to by iterator BSI
2822 with STMT. If PRESERVE_EH_INFO is true, the exception handling
2823 information of the original statement is preserved. */
2826 bsi_replace (const block_stmt_iterator *bsi, tree stmt, bool preserve_eh_info)
2829 tree orig_stmt = bsi_stmt (*bsi);
2831 SET_EXPR_LOCUS (stmt, EXPR_LOCUS (orig_stmt));
2832 set_bb_for_stmt (stmt, bsi->bb);
2834 /* Preserve EH region information from the original statement, if
2835 requested by the caller. */
2836 if (preserve_eh_info)
2838 eh_region = lookup_stmt_eh_region (orig_stmt);
2840 add_stmt_to_eh_region (stmt, eh_region);
2843 delink_stmt_imm_use (orig_stmt);
2844 *bsi_stmt_ptr (*bsi) = stmt;
2845 mark_stmt_modified (stmt);
2846 update_modified_stmts (stmt);
2850 /* Insert the statement pointed-to by BSI into edge E. Every attempt
2851 is made to place the statement in an existing basic block, but
2852 sometimes that isn't possible. When it isn't possible, the edge is
2853 split and the statement is added to the new block.
2855 In all cases, the returned *BSI points to the correct location. The
2856 return value is true if insertion should be done after the location,
2857 or false if it should be done before the location. If new basic block
2858 has to be created, it is stored in *NEW_BB. */
2861 tree_find_edge_insert_loc (edge e, block_stmt_iterator *bsi,
2862 basic_block *new_bb)
2864 basic_block dest, src;
2870 /* If the destination has one predecessor which has no PHI nodes,
2871 insert there. Except for the exit block.
2873 The requirement for no PHI nodes could be relaxed. Basically we
2874 would have to examine the PHIs to prove that none of them used
2875 the value set by the statement we want to insert on E. That
2876 hardly seems worth the effort. */
2877 if (single_pred_p (dest)
2878 && ! phi_nodes (dest)
2879 && dest != EXIT_BLOCK_PTR)
2881 *bsi = bsi_start (dest);
2882 if (bsi_end_p (*bsi))
2885 /* Make sure we insert after any leading labels. */
2886 tmp = bsi_stmt (*bsi);
2887 while (TREE_CODE (tmp) == LABEL_EXPR)
2890 if (bsi_end_p (*bsi))
2892 tmp = bsi_stmt (*bsi);
2895 if (bsi_end_p (*bsi))
2897 *bsi = bsi_last (dest);
2904 /* If the source has one successor, the edge is not abnormal and
2905 the last statement does not end a basic block, insert there.
2906 Except for the entry block. */
2908 if ((e->flags & EDGE_ABNORMAL) == 0
2909 && single_succ_p (src)
2910 && src != ENTRY_BLOCK_PTR)
2912 *bsi = bsi_last (src);
2913 if (bsi_end_p (*bsi))
2916 tmp = bsi_stmt (*bsi);
2917 if (!stmt_ends_bb_p (tmp))
2920 /* Insert code just before returning the value. We may need to decompose
2921 the return in the case it contains non-trivial operand. */
2922 if (TREE_CODE (tmp) == RETURN_EXPR)
2924 tree op = TREE_OPERAND (tmp, 0);
2925 if (!is_gimple_val (op))
2927 gcc_assert (TREE_CODE (op) == MODIFY_EXPR);
2928 bsi_insert_before (bsi, op, BSI_NEW_STMT);
2929 TREE_OPERAND (tmp, 0) = TREE_OPERAND (op, 0);
2936 /* Otherwise, create a new basic block, and split this edge. */
2937 dest = split_edge (e);
2940 e = single_pred_edge (dest);
2945 /* This routine will commit all pending edge insertions, creating any new
2946 basic blocks which are necessary. */
2949 bsi_commit_edge_inserts (void)
2955 bsi_commit_one_edge_insert (single_succ_edge (ENTRY_BLOCK_PTR), NULL);
2958 FOR_EACH_EDGE (e, ei, bb->succs)
2959 bsi_commit_one_edge_insert (e, NULL);
2963 /* Commit insertions pending at edge E. If a new block is created, set NEW_BB
2964 to this block, otherwise set it to NULL. */
2967 bsi_commit_one_edge_insert (edge e, basic_block *new_bb)
2971 if (PENDING_STMT (e))
2973 block_stmt_iterator bsi;
2974 tree stmt = PENDING_STMT (e);
2976 PENDING_STMT (e) = NULL_TREE;
2978 if (tree_find_edge_insert_loc (e, &bsi, new_bb))
2979 bsi_insert_after (&bsi, stmt, BSI_NEW_STMT);
2981 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
2986 /* Add STMT to the pending list of edge E. No actual insertion is
2987 made until a call to bsi_commit_edge_inserts () is made. */
2990 bsi_insert_on_edge (edge e, tree stmt)
2992 append_to_statement_list (stmt, &PENDING_STMT (e));
2995 /* Similar to bsi_insert_on_edge+bsi_commit_edge_inserts. If a new
2996 block has to be created, it is returned. */
2999 bsi_insert_on_edge_immediate (edge e, tree stmt)
3001 block_stmt_iterator bsi;
3002 basic_block new_bb = NULL;
3004 gcc_assert (!PENDING_STMT (e));
3006 if (tree_find_edge_insert_loc (e, &bsi, &new_bb))
3007 bsi_insert_after (&bsi, stmt, BSI_NEW_STMT);
3009 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
3014 /*---------------------------------------------------------------------------
3015 Tree specific functions for CFG manipulation
3016 ---------------------------------------------------------------------------*/
3018 /* Reinstall those PHI arguments queued in OLD_EDGE to NEW_EDGE. */
3021 reinstall_phi_args (edge new_edge, edge old_edge)
3025 if (!PENDING_STMT (old_edge))
3028 for (var = PENDING_STMT (old_edge), phi = phi_nodes (new_edge->dest);
3030 var = TREE_CHAIN (var), phi = PHI_CHAIN (phi))
3032 tree result = TREE_PURPOSE (var);
3033 tree arg = TREE_VALUE (var);
3035 gcc_assert (result == PHI_RESULT (phi));
3037 add_phi_arg (phi, arg, new_edge);
3040 PENDING_STMT (old_edge) = NULL;
3043 /* Returns the basic block after that the new basic block created
3044 by splitting edge EDGE_IN should be placed. Tries to keep the new block
3045 near its "logical" location. This is of most help to humans looking
3046 at debugging dumps. */
3049 split_edge_bb_loc (edge edge_in)
3051 basic_block dest = edge_in->dest;
3053 if (dest->prev_bb && find_edge (dest->prev_bb, dest))
3054 return edge_in->src;
3056 return dest->prev_bb;
3059 /* Split a (typically critical) edge EDGE_IN. Return the new block.
3060 Abort on abnormal edges. */
3063 tree_split_edge (edge edge_in)
3065 basic_block new_bb, after_bb, dest, src;
3068 /* Abnormal edges cannot be split. */
3069 gcc_assert (!(edge_in->flags & EDGE_ABNORMAL));
3072 dest = edge_in->dest;
3074 after_bb = split_edge_bb_loc (edge_in);
3076 new_bb = create_empty_bb (after_bb);
3077 new_bb->frequency = EDGE_FREQUENCY (edge_in);
3078 new_bb->count = edge_in->count;
3079 new_edge = make_edge (new_bb, dest, EDGE_FALLTHRU);
3080 new_edge->probability = REG_BR_PROB_BASE;
3081 new_edge->count = edge_in->count;
3083 e = redirect_edge_and_branch (edge_in, new_bb);
3085 reinstall_phi_args (new_edge, e);
3091 /* Return true when BB has label LABEL in it. */
3094 has_label_p (basic_block bb, tree label)
3096 block_stmt_iterator bsi;
3098 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3100 tree stmt = bsi_stmt (bsi);
3102 if (TREE_CODE (stmt) != LABEL_EXPR)
3104 if (LABEL_EXPR_LABEL (stmt) == label)
3111 /* Callback for walk_tree, check that all elements with address taken are
3112 properly noticed as such. The DATA is an int* that is 1 if TP was seen
3113 inside a PHI node. */
3116 verify_expr (tree *tp, int *walk_subtrees, void *data ATTRIBUTE_UNUSED)
3119 bool in_phi = (data != NULL);
3124 /* Check operand N for being valid GIMPLE and give error MSG if not. */
3125 #define CHECK_OP(N, MSG) \
3126 do { if (!is_gimple_val (TREE_OPERAND (t, N))) \
3127 { error (MSG); return TREE_OPERAND (t, N); }} while (0)
3129 switch (TREE_CODE (t))
3132 if (SSA_NAME_IN_FREE_LIST (t))
3134 error ("SSA name in freelist but still referenced");
3140 x = fold (ASSERT_EXPR_COND (t));
3141 if (x == boolean_false_node)
3143 error ("ASSERT_EXPR with an always-false condition");
3149 x = TREE_OPERAND (t, 0);
3150 if (TREE_CODE (x) == BIT_FIELD_REF
3151 && is_gimple_reg (TREE_OPERAND (x, 0)))
3153 error ("GIMPLE register modified with BIT_FIELD_REF");
3162 bool old_side_effects;
3165 bool new_side_effects;
3167 /* ??? tree-ssa-alias.c may have overlooked dead PHI nodes, missing
3168 dead PHIs that take the address of something. But if the PHI
3169 result is dead, the fact that it takes the address of anything
3170 is irrelevant. Because we can not tell from here if a PHI result
3171 is dead, we just skip this check for PHIs altogether. This means
3172 we may be missing "valid" checks, but what can you do?
3173 This was PR19217. */
3177 old_invariant = TREE_INVARIANT (t);
3178 old_constant = TREE_CONSTANT (t);
3179 old_side_effects = TREE_SIDE_EFFECTS (t);
3181 recompute_tree_invarant_for_addr_expr (t);
3182 new_invariant = TREE_INVARIANT (t);
3183 new_side_effects = TREE_SIDE_EFFECTS (t);
3184 new_constant = TREE_CONSTANT (t);
3186 if (old_invariant != new_invariant)
3188 error ("invariant not recomputed when ADDR_EXPR changed");
3192 if (old_constant != new_constant)
3194 error ("constant not recomputed when ADDR_EXPR changed");
3197 if (old_side_effects != new_side_effects)
3199 error ("side effects not recomputed when ADDR_EXPR changed");
3203 /* Skip any references (they will be checked when we recurse down the
3204 tree) and ensure that any variable used as a prefix is marked
3206 for (x = TREE_OPERAND (t, 0);
3207 handled_component_p (x);
3208 x = TREE_OPERAND (x, 0))
3211 if (TREE_CODE (x) != VAR_DECL && TREE_CODE (x) != PARM_DECL)
3213 if (!TREE_ADDRESSABLE (x))
3215 error ("address taken, but ADDRESSABLE bit not set");
3222 x = COND_EXPR_COND (t);
3223 if (TREE_CODE (TREE_TYPE (x)) != BOOLEAN_TYPE)
3225 error ("non-boolean used in condition");
3228 if (!is_gimple_condexpr (x))
3230 error ("invalid conditional operand");
3237 case FIX_TRUNC_EXPR:
3239 case FIX_FLOOR_EXPR:
3240 case FIX_ROUND_EXPR:
3245 case NON_LVALUE_EXPR:
3246 case TRUTH_NOT_EXPR:
3247 CHECK_OP (0, "invalid operand to unary operator");
3254 case ARRAY_RANGE_REF:
3256 case VIEW_CONVERT_EXPR:
3257 /* We have a nest of references. Verify that each of the operands
3258 that determine where to reference is either a constant or a variable,
3259 verify that the base is valid, and then show we've already checked
3261 while (handled_component_p (t))
3263 if (TREE_CODE (t) == COMPONENT_REF && TREE_OPERAND (t, 2))
3264 CHECK_OP (2, "invalid COMPONENT_REF offset operator");
3265 else if (TREE_CODE (t) == ARRAY_REF
3266 || TREE_CODE (t) == ARRAY_RANGE_REF)
3268 CHECK_OP (1, "invalid array index");
3269 if (TREE_OPERAND (t, 2))
3270 CHECK_OP (2, "invalid array lower bound");
3271 if (TREE_OPERAND (t, 3))
3272 CHECK_OP (3, "invalid array stride");
3274 else if (TREE_CODE (t) == BIT_FIELD_REF)
3276 CHECK_OP (1, "invalid operand to BIT_FIELD_REF");
3277 CHECK_OP (2, "invalid operand to BIT_FIELD_REF");
3280 t = TREE_OPERAND (t, 0);
3283 if (!CONSTANT_CLASS_P (t) && !is_gimple_lvalue (t))
3285 error ("invalid reference prefix");
3297 case UNORDERED_EXPR:
3308 case TRUNC_DIV_EXPR:
3310 case FLOOR_DIV_EXPR:
3311 case ROUND_DIV_EXPR:
3312 case TRUNC_MOD_EXPR:
3314 case FLOOR_MOD_EXPR:
3315 case ROUND_MOD_EXPR:
3317 case EXACT_DIV_EXPR:
3327 CHECK_OP (0, "invalid operand to binary operator");
3328 CHECK_OP (1, "invalid operand to binary operator");
3340 /* Verify STMT, return true if STMT is not in GIMPLE form.
3341 TODO: Implement type checking. */
3344 verify_stmt (tree stmt, bool last_in_block)
3348 if (!is_gimple_stmt (stmt))
3350 error ("is not a valid GIMPLE statement");
3354 addr = walk_tree (&stmt, verify_expr, NULL, NULL);
3357 debug_generic_stmt (addr);
3361 /* If the statement is marked as part of an EH region, then it is
3362 expected that the statement could throw. Verify that when we
3363 have optimizations that simplify statements such that we prove
3364 that they cannot throw, that we update other data structures
3366 if (lookup_stmt_eh_region (stmt) >= 0)
3368 if (!tree_could_throw_p (stmt))
3370 error ("statement marked for throw, but doesn%'t");
3373 if (!last_in_block && tree_can_throw_internal (stmt))
3375 error ("statement marked for throw in middle of block");
3383 debug_generic_stmt (stmt);
3388 /* Return true when the T can be shared. */
3391 tree_node_can_be_shared (tree t)
3393 if (IS_TYPE_OR_DECL_P (t)
3394 /* We check for constants explicitly since they are not considered
3395 gimple invariants if they overflowed. */
3396 || CONSTANT_CLASS_P (t)
3397 || is_gimple_min_invariant (t)
3398 || TREE_CODE (t) == SSA_NAME
3399 || t == error_mark_node)
3402 if (TREE_CODE (t) == CASE_LABEL_EXPR)
3405 while (((TREE_CODE (t) == ARRAY_REF || TREE_CODE (t) == ARRAY_RANGE_REF)
3406 /* We check for constants explicitly since they are not considered
3407 gimple invariants if they overflowed. */
3408 && (CONSTANT_CLASS_P (TREE_OPERAND (t, 1))
3409 || is_gimple_min_invariant (TREE_OPERAND (t, 1))))
3410 || (TREE_CODE (t) == COMPONENT_REF
3411 || TREE_CODE (t) == REALPART_EXPR
3412 || TREE_CODE (t) == IMAGPART_EXPR))
3413 t = TREE_OPERAND (t, 0);
3422 /* Called via walk_trees. Verify tree sharing. */
3425 verify_node_sharing (tree * tp, int *walk_subtrees, void *data)
3427 htab_t htab = (htab_t) data;
3430 if (tree_node_can_be_shared (*tp))
3432 *walk_subtrees = false;
3436 slot = htab_find_slot (htab, *tp, INSERT);
3445 /* Verify the GIMPLE statement chain. */
3451 block_stmt_iterator bsi;
3456 timevar_push (TV_TREE_STMT_VERIFY);
3457 htab = htab_create (37, htab_hash_pointer, htab_eq_pointer, NULL);
3464 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
3466 int phi_num_args = PHI_NUM_ARGS (phi);
3468 if (bb_for_stmt (phi) != bb)
3470 error ("bb_for_stmt (phi) is set to a wrong basic block");
3474 for (i = 0; i < phi_num_args; i++)
3476 tree t = PHI_ARG_DEF (phi, i);
3479 /* Addressable variables do have SSA_NAMEs but they
3480 are not considered gimple values. */
3481 if (TREE_CODE (t) != SSA_NAME
3482 && TREE_CODE (t) != FUNCTION_DECL
3483 && !is_gimple_val (t))
3485 error ("PHI def is not a GIMPLE value");
3486 debug_generic_stmt (phi);
3487 debug_generic_stmt (t);
3491 addr = walk_tree (&t, verify_expr, (void *) 1, NULL);
3494 debug_generic_stmt (addr);
3498 addr = walk_tree (&t, verify_node_sharing, htab, NULL);
3501 error ("incorrect sharing of tree nodes");
3502 debug_generic_stmt (phi);
3503 debug_generic_stmt (addr);
3509 for (bsi = bsi_start (bb); !bsi_end_p (bsi); )
3511 tree stmt = bsi_stmt (bsi);
3513 if (bb_for_stmt (stmt) != bb)
3515 error ("bb_for_stmt (stmt) is set to a wrong basic block");
3520 err |= verify_stmt (stmt, bsi_end_p (bsi));
3521 addr = walk_tree (&stmt, verify_node_sharing, htab, NULL);
3524 error ("incorrect sharing of tree nodes");
3525 debug_generic_stmt (stmt);
3526 debug_generic_stmt (addr);
3533 internal_error ("verify_stmts failed");
3536 timevar_pop (TV_TREE_STMT_VERIFY);
3540 /* Verifies that the flow information is OK. */
3543 tree_verify_flow_info (void)
3547 block_stmt_iterator bsi;
3552 if (ENTRY_BLOCK_PTR->stmt_list)
3554 error ("ENTRY_BLOCK has a statement list associated with it");
3558 if (EXIT_BLOCK_PTR->stmt_list)
3560 error ("EXIT_BLOCK has a statement list associated with it");
3564 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
3565 if (e->flags & EDGE_FALLTHRU)
3567 error ("fallthru to exit from bb %d", e->src->index);
3573 bool found_ctrl_stmt = false;
3577 /* Skip labels on the start of basic block. */
3578 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3580 tree prev_stmt = stmt;
3582 stmt = bsi_stmt (bsi);
3584 if (TREE_CODE (stmt) != LABEL_EXPR)
3587 if (prev_stmt && DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)))
3589 error ("nonlocal label %s is not first "
3590 "in a sequence of labels in bb %d",
3591 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt))),
3596 if (label_to_block (LABEL_EXPR_LABEL (stmt)) != bb)
3598 error ("label %s to block does not match in bb %d",
3599 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt))),
3604 if (decl_function_context (LABEL_EXPR_LABEL (stmt))
3605 != current_function_decl)
3607 error ("label %s has incorrect context in bb %d",
3608 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt))),
3614 /* Verify that body of basic block BB is free of control flow. */
3615 for (; !bsi_end_p (bsi); bsi_next (&bsi))
3617 tree stmt = bsi_stmt (bsi);
3619 if (found_ctrl_stmt)
3621 error ("control flow in the middle of basic block %d",
3626 if (stmt_ends_bb_p (stmt))
3627 found_ctrl_stmt = true;
3629 if (TREE_CODE (stmt) == LABEL_EXPR)
3631 error ("label %s in the middle of basic block %d",
3632 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt))),
3637 bsi = bsi_last (bb);
3638 if (bsi_end_p (bsi))
3641 stmt = bsi_stmt (bsi);
3643 err |= verify_eh_edges (stmt);
3645 if (is_ctrl_stmt (stmt))
3647 FOR_EACH_EDGE (e, ei, bb->succs)
3648 if (e->flags & EDGE_FALLTHRU)
3650 error ("fallthru edge after a control statement in bb %d",
3656 switch (TREE_CODE (stmt))
3662 if (TREE_CODE (COND_EXPR_THEN (stmt)) != GOTO_EXPR
3663 || TREE_CODE (COND_EXPR_ELSE (stmt)) != GOTO_EXPR)
3665 error ("structured COND_EXPR at the end of bb %d", bb->index);
3669 extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
3671 if (!true_edge || !false_edge
3672 || !(true_edge->flags & EDGE_TRUE_VALUE)
3673 || !(false_edge->flags & EDGE_FALSE_VALUE)
3674 || (true_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL))
3675 || (false_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL))
3676 || EDGE_COUNT (bb->succs) >= 3)
3678 error ("wrong outgoing edge flags at end of bb %d",
3683 if (!has_label_p (true_edge->dest,
3684 GOTO_DESTINATION (COND_EXPR_THEN (stmt))))
3686 error ("%<then%> label does not match edge at end of bb %d",
3691 if (!has_label_p (false_edge->dest,
3692 GOTO_DESTINATION (COND_EXPR_ELSE (stmt))))
3694 error ("%<else%> label does not match edge at end of bb %d",
3702 if (simple_goto_p (stmt))
3704 error ("explicit goto at end of bb %d", bb->index);
3709 /* FIXME. We should double check that the labels in the
3710 destination blocks have their address taken. */
3711 FOR_EACH_EDGE (e, ei, bb->succs)
3712 if ((e->flags & (EDGE_FALLTHRU | EDGE_TRUE_VALUE
3713 | EDGE_FALSE_VALUE))
3714 || !(e->flags & EDGE_ABNORMAL))
3716 error ("wrong outgoing edge flags at end of bb %d",
3724 if (!single_succ_p (bb)
3725 || (single_succ_edge (bb)->flags
3726 & (EDGE_FALLTHRU | EDGE_ABNORMAL
3727 | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
3729 error ("wrong outgoing edge flags at end of bb %d", bb->index);
3732 if (single_succ (bb) != EXIT_BLOCK_PTR)
3734 error ("return edge does not point to exit in bb %d",
3747 vec = SWITCH_LABELS (stmt);
3748 n = TREE_VEC_LENGTH (vec);
3750 /* Mark all the destination basic blocks. */
3751 for (i = 0; i < n; ++i)
3753 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
3754 basic_block label_bb = label_to_block (lab);
3756 gcc_assert (!label_bb->aux || label_bb->aux == (void *)1);
3757 label_bb->aux = (void *)1;
3760 /* Verify that the case labels are sorted. */
3761 prev = TREE_VEC_ELT (vec, 0);
3762 for (i = 1; i < n - 1; ++i)
3764 tree c = TREE_VEC_ELT (vec, i);
3767 error ("found default case not at end of case vector");
3771 if (! tree_int_cst_lt (CASE_LOW (prev), CASE_LOW (c)))
3773 error ("case labels not sorted:");
3774 print_generic_expr (stderr, prev, 0);
3775 fprintf (stderr," is greater than ");
3776 print_generic_expr (stderr, c, 0);
3777 fprintf (stderr," but comes before it.\n");
3782 if (CASE_LOW (TREE_VEC_ELT (vec, n - 1)))
3784 error ("no default case found at end of case vector");
3788 FOR_EACH_EDGE (e, ei, bb->succs)
3792 error ("extra outgoing edge %d->%d",
3793 bb->index, e->dest->index);
3796 e->dest->aux = (void *)2;
3797 if ((e->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL
3798 | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
3800 error ("wrong outgoing edge flags at end of bb %d",
3806 /* Check that we have all of them. */
3807 for (i = 0; i < n; ++i)
3809 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
3810 basic_block label_bb = label_to_block (lab);
3812 if (label_bb->aux != (void *)2)
3814 error ("missing edge %i->%i",
3815 bb->index, label_bb->index);
3820 FOR_EACH_EDGE (e, ei, bb->succs)
3821 e->dest->aux = (void *)0;
3828 if (dom_computed[CDI_DOMINATORS] >= DOM_NO_FAST_QUERY)
3829 verify_dominators (CDI_DOMINATORS);
3835 /* Updates phi nodes after creating a forwarder block joined
3836 by edge FALLTHRU. */
3839 tree_make_forwarder_block (edge fallthru)
3843 basic_block dummy, bb;
3844 tree phi, new_phi, var;
3846 dummy = fallthru->src;
3847 bb = fallthru->dest;
3849 if (single_pred_p (bb))
3852 /* If we redirected a branch we must create new phi nodes at the
3854 for (phi = phi_nodes (dummy); phi; phi = PHI_CHAIN (phi))
3856 var = PHI_RESULT (phi);
3857 new_phi = create_phi_node (var, bb);
3858 SSA_NAME_DEF_STMT (var) = new_phi;
3859 SET_PHI_RESULT (phi, make_ssa_name (SSA_NAME_VAR (var), phi));
3860 add_phi_arg (new_phi, PHI_RESULT (phi), fallthru);
3863 /* Ensure that the PHI node chain is in the same order. */
3864 set_phi_nodes (bb, phi_reverse (phi_nodes (bb)));
3866 /* Add the arguments we have stored on edges. */
3867 FOR_EACH_EDGE (e, ei, bb->preds)
3872 flush_pending_stmts (e);
3877 /* Return a non-special label in the head of basic block BLOCK.
3878 Create one if it doesn't exist. */
3881 tree_block_label (basic_block bb)
3883 block_stmt_iterator i, s = bsi_start (bb);
3887 for (i = s; !bsi_end_p (i); first = false, bsi_next (&i))
3889 stmt = bsi_stmt (i);
3890 if (TREE_CODE (stmt) != LABEL_EXPR)
3892 label = LABEL_EXPR_LABEL (stmt);
3893 if (!DECL_NONLOCAL (label))
3896 bsi_move_before (&i, &s);
3901 label = create_artificial_label ();
3902 stmt = build1 (LABEL_EXPR, void_type_node, label);
3903 bsi_insert_before (&s, stmt, BSI_NEW_STMT);
3908 /* Attempt to perform edge redirection by replacing a possibly complex
3909 jump instruction by a goto or by removing the jump completely.
3910 This can apply only if all edges now point to the same block. The
3911 parameters and return values are equivalent to
3912 redirect_edge_and_branch. */
3915 tree_try_redirect_by_replacing_jump (edge e, basic_block target)
3917 basic_block src = e->src;
3918 block_stmt_iterator b;
3921 /* We can replace or remove a complex jump only when we have exactly
3923 if (EDGE_COUNT (src->succs) != 2
3924 /* Verify that all targets will be TARGET. Specifically, the
3925 edge that is not E must also go to TARGET. */
3926 || EDGE_SUCC (src, EDGE_SUCC (src, 0) == e)->dest != target)
3932 stmt = bsi_stmt (b);
3934 if (TREE_CODE (stmt) == COND_EXPR
3935 || TREE_CODE (stmt) == SWITCH_EXPR)
3938 e = ssa_redirect_edge (e, target);
3939 e->flags = EDGE_FALLTHRU;
3947 /* Redirect E to DEST. Return NULL on failure. Otherwise, return the
3948 edge representing the redirected branch. */
3951 tree_redirect_edge_and_branch (edge e, basic_block dest)
3953 basic_block bb = e->src;
3954 block_stmt_iterator bsi;
3958 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
3961 if (e->src != ENTRY_BLOCK_PTR
3962 && (ret = tree_try_redirect_by_replacing_jump (e, dest)))
3965 if (e->dest == dest)
3968 label = tree_block_label (dest);
3970 bsi = bsi_last (bb);
3971 stmt = bsi_end_p (bsi) ? NULL : bsi_stmt (bsi);
3973 switch (stmt ? TREE_CODE (stmt) : ERROR_MARK)
3976 stmt = (e->flags & EDGE_TRUE_VALUE
3977 ? COND_EXPR_THEN (stmt)
3978 : COND_EXPR_ELSE (stmt));
3979 GOTO_DESTINATION (stmt) = label;
3983 /* No non-abnormal edges should lead from a non-simple goto, and
3984 simple ones should be represented implicitly. */
3989 tree cases = get_cases_for_edge (e, stmt);
3991 /* If we have a list of cases associated with E, then use it
3992 as it's a lot faster than walking the entire case vector. */
3995 edge e2 = find_edge (e->src, dest);
4002 CASE_LABEL (cases) = label;
4003 cases = TREE_CHAIN (cases);
4006 /* If there was already an edge in the CFG, then we need
4007 to move all the cases associated with E to E2. */
4010 tree cases2 = get_cases_for_edge (e2, stmt);
4012 TREE_CHAIN (last) = TREE_CHAIN (cases2);
4013 TREE_CHAIN (cases2) = first;
4018 tree vec = SWITCH_LABELS (stmt);
4019 size_t i, n = TREE_VEC_LENGTH (vec);
4021 for (i = 0; i < n; i++)
4023 tree elt = TREE_VEC_ELT (vec, i);
4025 if (label_to_block (CASE_LABEL (elt)) == e->dest)
4026 CASE_LABEL (elt) = label;
4035 e->flags |= EDGE_FALLTHRU;
4039 /* Otherwise it must be a fallthru edge, and we don't need to
4040 do anything besides redirecting it. */
4041 gcc_assert (e->flags & EDGE_FALLTHRU);
4045 /* Update/insert PHI nodes as necessary. */
4047 /* Now update the edges in the CFG. */
4048 e = ssa_redirect_edge (e, dest);
4054 /* Simple wrapper, as we can always redirect fallthru edges. */
4057 tree_redirect_edge_and_branch_force (edge e, basic_block dest)
4059 e = tree_redirect_edge_and_branch (e, dest);
4066 /* Splits basic block BB after statement STMT (but at least after the
4067 labels). If STMT is NULL, BB is split just after the labels. */
4070 tree_split_block (basic_block bb, void *stmt)
4072 block_stmt_iterator bsi, bsi_tgt;
4078 new_bb = create_empty_bb (bb);
4080 /* Redirect the outgoing edges. */
4081 new_bb->succs = bb->succs;
4083 FOR_EACH_EDGE (e, ei, new_bb->succs)
4086 if (stmt && TREE_CODE ((tree) stmt) == LABEL_EXPR)
4089 /* Move everything from BSI to the new basic block. */
4090 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4092 act = bsi_stmt (bsi);
4093 if (TREE_CODE (act) == LABEL_EXPR)
4106 bsi_tgt = bsi_start (new_bb);
4107 while (!bsi_end_p (bsi))
4109 act = bsi_stmt (bsi);
4111 bsi_insert_after (&bsi_tgt, act, BSI_NEW_STMT);
4118 /* Moves basic block BB after block AFTER. */
4121 tree_move_block_after (basic_block bb, basic_block after)
4123 if (bb->prev_bb == after)
4127 link_block (bb, after);
4133 /* Return true if basic_block can be duplicated. */
4136 tree_can_duplicate_bb_p (basic_block bb ATTRIBUTE_UNUSED)
4142 /* Create a duplicate of the basic block BB. NOTE: This does not
4143 preserve SSA form. */
4146 tree_duplicate_bb (basic_block bb)
4149 block_stmt_iterator bsi, bsi_tgt;
4152 new_bb = create_empty_bb (EXIT_BLOCK_PTR->prev_bb);
4154 /* Copy the PHI nodes. We ignore PHI node arguments here because
4155 the incoming edges have not been setup yet. */
4156 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
4158 tree copy = create_phi_node (PHI_RESULT (phi), new_bb);
4159 create_new_def_for (PHI_RESULT (copy), copy, PHI_RESULT_PTR (copy));
4162 /* Keep the chain of PHI nodes in the same order so that they can be
4163 updated by ssa_redirect_edge. */
4164 set_phi_nodes (new_bb, phi_reverse (phi_nodes (new_bb)));
4166 bsi_tgt = bsi_start (new_bb);
4167 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4169 def_operand_p def_p;
4170 ssa_op_iter op_iter;
4174 stmt = bsi_stmt (bsi);
4175 if (TREE_CODE (stmt) == LABEL_EXPR)
4178 /* Create a new copy of STMT and duplicate STMT's virtual
4180 copy = unshare_expr (stmt);
4181 bsi_insert_after (&bsi_tgt, copy, BSI_NEW_STMT);
4182 copy_virtual_operands (copy, stmt);
4183 region = lookup_stmt_eh_region (stmt);
4185 add_stmt_to_eh_region (copy, region);
4187 /* Create new names for all the definitions created by COPY and
4188 add replacement mappings for each new name. */
4189 FOR_EACH_SSA_DEF_OPERAND (def_p, copy, op_iter, SSA_OP_ALL_DEFS)
4190 create_new_def_for (DEF_FROM_PTR (def_p), copy, def_p);
4197 /* Basic block BB_COPY was created by code duplication. Add phi node
4198 arguments for edges going out of BB_COPY. The blocks that were
4199 duplicated have BB_DUPLICATED set. */
4202 add_phi_args_after_copy_bb (basic_block bb_copy)
4204 basic_block bb, dest;
4207 tree phi, phi_copy, phi_next, def;
4209 bb = get_bb_original (bb_copy);
4211 FOR_EACH_EDGE (e_copy, ei, bb_copy->succs)
4213 if (!phi_nodes (e_copy->dest))
4216 if (e_copy->dest->flags & BB_DUPLICATED)
4217 dest = get_bb_original (e_copy->dest);
4219 dest = e_copy->dest;
4221 e = find_edge (bb, dest);
4224 /* During loop unrolling the target of the latch edge is copied.
4225 In this case we are not looking for edge to dest, but to
4226 duplicated block whose original was dest. */
4227 FOR_EACH_EDGE (e, ei, bb->succs)
4228 if ((e->dest->flags & BB_DUPLICATED)
4229 && get_bb_original (e->dest) == dest)
4232 gcc_assert (e != NULL);
4235 for (phi = phi_nodes (e->dest), phi_copy = phi_nodes (e_copy->dest);
4237 phi = phi_next, phi_copy = PHI_CHAIN (phi_copy))
4239 phi_next = PHI_CHAIN (phi);
4240 def = PHI_ARG_DEF_FROM_EDGE (phi, e);
4241 add_phi_arg (phi_copy, def, e_copy);
4246 /* Blocks in REGION_COPY array of length N_REGION were created by
4247 duplication of basic blocks. Add phi node arguments for edges
4248 going from these blocks. */
4251 add_phi_args_after_copy (basic_block *region_copy, unsigned n_region)
4255 for (i = 0; i < n_region; i++)
4256 region_copy[i]->flags |= BB_DUPLICATED;
4258 for (i = 0; i < n_region; i++)
4259 add_phi_args_after_copy_bb (region_copy[i]);
4261 for (i = 0; i < n_region; i++)
4262 region_copy[i]->flags &= ~BB_DUPLICATED;
4265 /* Duplicates a REGION (set of N_REGION basic blocks) with just a single
4266 important exit edge EXIT. By important we mean that no SSA name defined
4267 inside region is live over the other exit edges of the region. All entry
4268 edges to the region must go to ENTRY->dest. The edge ENTRY is redirected
4269 to the duplicate of the region. SSA form, dominance and loop information
4270 is updated. The new basic blocks are stored to REGION_COPY in the same
4271 order as they had in REGION, provided that REGION_COPY is not NULL.
4272 The function returns false if it is unable to copy the region,
4276 tree_duplicate_sese_region (edge entry, edge exit,
4277 basic_block *region, unsigned n_region,
4278 basic_block *region_copy)
4281 bool free_region_copy = false, copying_header = false;
4282 struct loop *loop = entry->dest->loop_father;
4286 int total_freq = 0, entry_freq = 0;
4287 gcov_type total_count = 0, entry_count = 0;
4289 if (!can_copy_bbs_p (region, n_region))
4292 /* Some sanity checking. Note that we do not check for all possible
4293 missuses of the functions. I.e. if you ask to copy something weird,
4294 it will work, but the state of structures probably will not be
4296 for (i = 0; i < n_region; i++)
4298 /* We do not handle subloops, i.e. all the blocks must belong to the
4300 if (region[i]->loop_father != loop)
4303 if (region[i] != entry->dest
4304 && region[i] == loop->header)
4310 /* In case the function is used for loop header copying (which is the primary
4311 use), ensure that EXIT and its copy will be new latch and entry edges. */
4312 if (loop->header == entry->dest)
4314 copying_header = true;
4315 loop->copy = loop->outer;
4317 if (!dominated_by_p (CDI_DOMINATORS, loop->latch, exit->src))
4320 for (i = 0; i < n_region; i++)
4321 if (region[i] != exit->src
4322 && dominated_by_p (CDI_DOMINATORS, region[i], exit->src))
4328 region_copy = xmalloc (sizeof (basic_block) * n_region);
4329 free_region_copy = true;
4332 gcc_assert (!need_ssa_update_p ());
4334 /* Record blocks outside the region that are dominated by something
4336 doms = xmalloc (sizeof (basic_block) * n_basic_blocks);
4337 initialize_original_copy_tables ();
4339 n_doms = get_dominated_by_region (CDI_DOMINATORS, region, n_region, doms);
4341 if (entry->dest->count)
4343 total_count = entry->dest->count;
4344 entry_count = entry->count;
4345 /* Fix up corner cases, to avoid division by zero or creation of negative
4347 if (entry_count > total_count)
4348 entry_count = total_count;
4352 total_freq = entry->dest->frequency;
4353 entry_freq = EDGE_FREQUENCY (entry);
4354 /* Fix up corner cases, to avoid division by zero or creation of negative
4356 if (total_freq == 0)
4358 else if (entry_freq > total_freq)
4359 entry_freq = total_freq;
4362 copy_bbs (region, n_region, region_copy, &exit, 1, &exit_copy, loop,
4363 split_edge_bb_loc (entry));
4366 scale_bbs_frequencies_gcov_type (region, n_region,
4367 total_count - entry_count,
4369 scale_bbs_frequencies_gcov_type (region_copy, n_region, entry_count,
4374 scale_bbs_frequencies_int (region, n_region, total_freq - entry_freq,
4376 scale_bbs_frequencies_int (region_copy, n_region, entry_freq, total_freq);
4381 loop->header = exit->dest;
4382 loop->latch = exit->src;
4385 /* Redirect the entry and add the phi node arguments. */
4386 redirected = redirect_edge_and_branch (entry, get_bb_copy (entry->dest));
4387 gcc_assert (redirected != NULL);
4388 flush_pending_stmts (entry);
4390 /* Concerning updating of dominators: We must recount dominators
4391 for entry block and its copy. Anything that is outside of the
4392 region, but was dominated by something inside needs recounting as
4394 set_immediate_dominator (CDI_DOMINATORS, entry->dest, entry->src);
4395 doms[n_doms++] = get_bb_original (entry->dest);
4396 iterate_fix_dominators (CDI_DOMINATORS, doms, n_doms);
4399 /* Add the other PHI node arguments. */
4400 add_phi_args_after_copy (region_copy, n_region);
4402 /* Update the SSA web. */
4403 update_ssa (TODO_update_ssa);
4405 if (free_region_copy)
4408 free_original_copy_tables ();
4413 /* Dump FUNCTION_DECL FN to file FILE using FLAGS (see TDF_* in tree.h) */
4416 dump_function_to_file (tree fn, FILE *file, int flags)
4418 tree arg, vars, var;
4419 bool ignore_topmost_bind = false, any_var = false;
4423 fprintf (file, "%s (", lang_hooks.decl_printable_name (fn, 2));
4425 arg = DECL_ARGUMENTS (fn);
4428 print_generic_expr (file, arg, dump_flags);
4429 if (TREE_CHAIN (arg))
4430 fprintf (file, ", ");
4431 arg = TREE_CHAIN (arg);
4433 fprintf (file, ")\n");
4435 if (flags & TDF_DETAILS)
4436 dump_eh_tree (file, DECL_STRUCT_FUNCTION (fn));
4437 if (flags & TDF_RAW)
4439 dump_node (fn, TDF_SLIM | flags, file);
4443 /* When GIMPLE is lowered, the variables are no longer available in
4444 BIND_EXPRs, so display them separately. */
4445 if (cfun && cfun->decl == fn && cfun->unexpanded_var_list)
4447 ignore_topmost_bind = true;
4449 fprintf (file, "{\n");
4450 for (vars = cfun->unexpanded_var_list; vars; vars = TREE_CHAIN (vars))
4452 var = TREE_VALUE (vars);
4454 print_generic_decl (file, var, flags);
4455 fprintf (file, "\n");
4461 if (cfun && cfun->decl == fn && cfun->cfg && basic_block_info)
4463 /* Make a CFG based dump. */
4464 check_bb_profile (ENTRY_BLOCK_PTR, file);
4465 if (!ignore_topmost_bind)
4466 fprintf (file, "{\n");
4468 if (any_var && n_basic_blocks)
4469 fprintf (file, "\n");
4472 dump_generic_bb (file, bb, 2, flags);
4474 fprintf (file, "}\n");
4475 check_bb_profile (EXIT_BLOCK_PTR, file);
4481 /* Make a tree based dump. */
4482 chain = DECL_SAVED_TREE (fn);
4484 if (TREE_CODE (chain) == BIND_EXPR)
4486 if (ignore_topmost_bind)
4488 chain = BIND_EXPR_BODY (chain);
4496 if (!ignore_topmost_bind)
4497 fprintf (file, "{\n");
4502 fprintf (file, "\n");
4504 print_generic_stmt_indented (file, chain, flags, indent);
4505 if (ignore_topmost_bind)
4506 fprintf (file, "}\n");
4509 fprintf (file, "\n\n");
4513 /* Pretty print of the loops intermediate representation. */
4514 static void print_loop (FILE *, struct loop *, int);
4515 static void print_pred_bbs (FILE *, basic_block bb);
4516 static void print_succ_bbs (FILE *, basic_block bb);
4519 /* Print on FILE the indexes for the predecessors of basic_block BB. */
4522 print_pred_bbs (FILE *file, basic_block bb)
4527 FOR_EACH_EDGE (e, ei, bb->preds)
4528 fprintf (file, "bb_%d ", e->src->index);
4532 /* Print on FILE the indexes for the successors of basic_block BB. */
4535 print_succ_bbs (FILE *file, basic_block bb)
4540 FOR_EACH_EDGE (e, ei, bb->succs)
4541 fprintf (file, "bb_%d ", e->dest->index);
4545 /* Pretty print LOOP on FILE, indented INDENT spaces. */
4548 print_loop (FILE *file, struct loop *loop, int indent)
4556 s_indent = (char *) alloca ((size_t) indent + 1);
4557 memset ((void *) s_indent, ' ', (size_t) indent);
4558 s_indent[indent] = '\0';
4560 /* Print the loop's header. */
4561 fprintf (file, "%sloop_%d\n", s_indent, loop->num);
4563 /* Print the loop's body. */
4564 fprintf (file, "%s{\n", s_indent);
4566 if (bb->loop_father == loop)
4568 /* Print the basic_block's header. */
4569 fprintf (file, "%s bb_%d (preds = {", s_indent, bb->index);
4570 print_pred_bbs (file, bb);
4571 fprintf (file, "}, succs = {");
4572 print_succ_bbs (file, bb);
4573 fprintf (file, "})\n");
4575 /* Print the basic_block's body. */
4576 fprintf (file, "%s {\n", s_indent);
4577 tree_dump_bb (bb, file, indent + 4);
4578 fprintf (file, "%s }\n", s_indent);
4581 print_loop (file, loop->inner, indent + 2);
4582 fprintf (file, "%s}\n", s_indent);
4583 print_loop (file, loop->next, indent);
4587 /* Follow a CFG edge from the entry point of the program, and on entry
4588 of a loop, pretty print the loop structure on FILE. */
4591 print_loop_ir (FILE *file)
4595 bb = BASIC_BLOCK (0);
4596 if (bb && bb->loop_father)
4597 print_loop (file, bb->loop_father, 0);
4601 /* Debugging loops structure at tree level. */
4604 debug_loop_ir (void)
4606 print_loop_ir (stderr);
4610 /* Return true if BB ends with a call, possibly followed by some
4611 instructions that must stay with the call. Return false,
4615 tree_block_ends_with_call_p (basic_block bb)
4617 block_stmt_iterator bsi = bsi_last (bb);
4618 return get_call_expr_in (bsi_stmt (bsi)) != NULL;
4622 /* Return true if BB ends with a conditional branch. Return false,
4626 tree_block_ends_with_condjump_p (basic_block bb)
4628 tree stmt = last_stmt (bb);
4629 return (stmt && TREE_CODE (stmt) == COND_EXPR);
4633 /* Return true if we need to add fake edge to exit at statement T.
4634 Helper function for tree_flow_call_edges_add. */
4637 need_fake_edge_p (tree t)
4641 /* NORETURN and LONGJMP calls already have an edge to exit.
4642 CONST and PURE calls do not need one.
4643 We don't currently check for CONST and PURE here, although
4644 it would be a good idea, because those attributes are
4645 figured out from the RTL in mark_constant_function, and
4646 the counter incrementation code from -fprofile-arcs
4647 leads to different results from -fbranch-probabilities. */
4648 call = get_call_expr_in (t);
4650 && !(call_expr_flags (call) & ECF_NORETURN))
4653 if (TREE_CODE (t) == ASM_EXPR
4654 && (ASM_VOLATILE_P (t) || ASM_INPUT_P (t)))
4661 /* Add fake edges to the function exit for any non constant and non
4662 noreturn calls, volatile inline assembly in the bitmap of blocks
4663 specified by BLOCKS or to the whole CFG if BLOCKS is zero. Return
4664 the number of blocks that were split.
4666 The goal is to expose cases in which entering a basic block does
4667 not imply that all subsequent instructions must be executed. */
4670 tree_flow_call_edges_add (sbitmap blocks)
4673 int blocks_split = 0;
4674 int last_bb = last_basic_block;
4675 bool check_last_block = false;
4677 if (n_basic_blocks == 0)
4681 check_last_block = true;
4683 check_last_block = TEST_BIT (blocks, EXIT_BLOCK_PTR->prev_bb->index);
4685 /* In the last basic block, before epilogue generation, there will be
4686 a fallthru edge to EXIT. Special care is required if the last insn
4687 of the last basic block is a call because make_edge folds duplicate
4688 edges, which would result in the fallthru edge also being marked
4689 fake, which would result in the fallthru edge being removed by
4690 remove_fake_edges, which would result in an invalid CFG.
4692 Moreover, we can't elide the outgoing fake edge, since the block
4693 profiler needs to take this into account in order to solve the minimal
4694 spanning tree in the case that the call doesn't return.
4696 Handle this by adding a dummy instruction in a new last basic block. */
4697 if (check_last_block)
4699 basic_block bb = EXIT_BLOCK_PTR->prev_bb;
4700 block_stmt_iterator bsi = bsi_last (bb);
4702 if (!bsi_end_p (bsi))
4705 if (need_fake_edge_p (t))
4709 e = find_edge (bb, EXIT_BLOCK_PTR);
4712 bsi_insert_on_edge (e, build_empty_stmt ());
4713 bsi_commit_edge_inserts ();
4718 /* Now add fake edges to the function exit for any non constant
4719 calls since there is no way that we can determine if they will
4721 for (i = 0; i < last_bb; i++)
4723 basic_block bb = BASIC_BLOCK (i);
4724 block_stmt_iterator bsi;
4725 tree stmt, last_stmt;
4730 if (blocks && !TEST_BIT (blocks, i))
4733 bsi = bsi_last (bb);
4734 if (!bsi_end_p (bsi))
4736 last_stmt = bsi_stmt (bsi);
4739 stmt = bsi_stmt (bsi);
4740 if (need_fake_edge_p (stmt))
4743 /* The handling above of the final block before the
4744 epilogue should be enough to verify that there is
4745 no edge to the exit block in CFG already.
4746 Calling make_edge in such case would cause us to
4747 mark that edge as fake and remove it later. */
4748 #ifdef ENABLE_CHECKING
4749 if (stmt == last_stmt)
4751 e = find_edge (bb, EXIT_BLOCK_PTR);
4752 gcc_assert (e == NULL);
4756 /* Note that the following may create a new basic block
4757 and renumber the existing basic blocks. */
4758 if (stmt != last_stmt)
4760 e = split_block (bb, stmt);
4764 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
4768 while (!bsi_end_p (bsi));
4773 verify_flow_info ();
4775 return blocks_split;
4779 tree_purge_dead_eh_edges (basic_block bb)
4781 bool changed = false;
4784 tree stmt = last_stmt (bb);
4786 if (stmt && tree_can_throw_internal (stmt))
4789 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
4791 if (e->flags & EDGE_EH)
4800 /* Removal of dead EH edges might change dominators of not
4801 just immediate successors. E.g. when bb1 is changed so that
4802 it no longer can throw and bb1->bb3 and bb1->bb4 are dead
4803 eh edges purged by this function in:
4815 idom(bb5) must be recomputed. For now just free the dominance
4818 free_dominance_info (CDI_DOMINATORS);
4824 tree_purge_all_dead_eh_edges (bitmap blocks)
4826 bool changed = false;
4830 EXECUTE_IF_SET_IN_BITMAP (blocks, 0, i, bi)
4832 changed |= tree_purge_dead_eh_edges (BASIC_BLOCK (i));
4838 /* This function is called whenever a new edge is created or
4842 tree_execute_on_growing_pred (edge e)
4844 basic_block bb = e->dest;
4847 reserve_phi_args_for_new_edge (bb);
4850 /* This function is called immediately before edge E is removed from
4851 the edge vector E->dest->preds. */
4854 tree_execute_on_shrinking_pred (edge e)
4856 if (phi_nodes (e->dest))
4857 remove_phi_args (e);
4860 /*---------------------------------------------------------------------------
4861 Helper functions for Loop versioning
4862 ---------------------------------------------------------------------------*/
4864 /* Adjust phi nodes for 'first' basic block. 'second' basic block is a copy
4865 of 'first'. Both of them are dominated by 'new_head' basic block. When
4866 'new_head' was created by 'second's incoming edge it received phi arguments
4867 on the edge by split_edge(). Later, additional edge 'e' was created to
4868 connect 'new_head' and 'first'. Now this routine adds phi args on this
4869 additional edge 'e' that new_head to second edge received as part of edge
4874 tree_lv_adjust_loop_header_phi (basic_block first, basic_block second,
4875 basic_block new_head, edge e)
4878 edge e2 = find_edge (new_head, second);
4880 /* Because NEW_HEAD has been created by splitting SECOND's incoming
4881 edge, we should always have an edge from NEW_HEAD to SECOND. */
4882 gcc_assert (e2 != NULL);
4884 /* Browse all 'second' basic block phi nodes and add phi args to
4885 edge 'e' for 'first' head. PHI args are always in correct order. */
4887 for (phi2 = phi_nodes (second), phi1 = phi_nodes (first);
4889 phi2 = PHI_CHAIN (phi2), phi1 = PHI_CHAIN (phi1))
4891 tree def = PHI_ARG_DEF (phi2, e2->dest_idx);
4892 add_phi_arg (phi1, def, e);
4896 /* Adds a if else statement to COND_BB with condition COND_EXPR.
4897 SECOND_HEAD is the destination of the THEN and FIRST_HEAD is
4898 the destination of the ELSE part. */
4900 tree_lv_add_condition_to_bb (basic_block first_head, basic_block second_head,
4901 basic_block cond_bb, void *cond_e)
4903 block_stmt_iterator bsi;
4904 tree goto1 = NULL_TREE;
4905 tree goto2 = NULL_TREE;
4906 tree new_cond_expr = NULL_TREE;
4907 tree cond_expr = (tree) cond_e;
4910 /* Build new conditional expr */
4911 goto1 = build1 (GOTO_EXPR, void_type_node, tree_block_label (first_head));
4912 goto2 = build1 (GOTO_EXPR, void_type_node, tree_block_label (second_head));
4913 new_cond_expr = build3 (COND_EXPR, void_type_node, cond_expr, goto1, goto2);
4915 /* Add new cond in cond_bb. */
4916 bsi = bsi_start (cond_bb);
4917 bsi_insert_after (&bsi, new_cond_expr, BSI_NEW_STMT);
4918 /* Adjust edges appropriately to connect new head with first head
4919 as well as second head. */
4920 e0 = single_succ_edge (cond_bb);
4921 e0->flags &= ~EDGE_FALLTHRU;
4922 e0->flags |= EDGE_FALSE_VALUE;
4925 struct cfg_hooks tree_cfg_hooks = {
4927 tree_verify_flow_info,
4928 tree_dump_bb, /* dump_bb */
4929 create_bb, /* create_basic_block */
4930 tree_redirect_edge_and_branch,/* redirect_edge_and_branch */
4931 tree_redirect_edge_and_branch_force,/* redirect_edge_and_branch_force */
4932 remove_bb, /* delete_basic_block */
4933 tree_split_block, /* split_block */
4934 tree_move_block_after, /* move_block_after */
4935 tree_can_merge_blocks_p, /* can_merge_blocks_p */
4936 tree_merge_blocks, /* merge_blocks */
4937 tree_predict_edge, /* predict_edge */
4938 tree_predicted_by_p, /* predicted_by_p */
4939 tree_can_duplicate_bb_p, /* can_duplicate_block_p */
4940 tree_duplicate_bb, /* duplicate_block */
4941 tree_split_edge, /* split_edge */
4942 tree_make_forwarder_block, /* make_forward_block */
4943 NULL, /* tidy_fallthru_edge */
4944 tree_block_ends_with_call_p, /* block_ends_with_call_p */
4945 tree_block_ends_with_condjump_p, /* block_ends_with_condjump_p */
4946 tree_flow_call_edges_add, /* flow_call_edges_add */
4947 tree_execute_on_growing_pred, /* execute_on_growing_pred */
4948 tree_execute_on_shrinking_pred, /* execute_on_shrinking_pred */
4949 tree_duplicate_loop_to_header_edge, /* duplicate loop for trees */
4950 tree_lv_add_condition_to_bb, /* lv_add_condition_to_bb */
4951 tree_lv_adjust_loop_header_phi, /* lv_adjust_loop_header_phi*/
4952 extract_true_false_edges_from_block, /* extract_cond_bb_edges */
4953 flush_pending_stmts /* flush_pending_stmts */
4957 /* Split all critical edges. */
4960 split_critical_edges (void)
4966 /* split_edge can redirect edges out of SWITCH_EXPRs, which can get
4967 expensive. So we want to enable recording of edge to CASE_LABEL_EXPR
4968 mappings around the calls to split_edge. */
4969 start_recording_case_labels ();
4972 FOR_EACH_EDGE (e, ei, bb->succs)
4973 if (EDGE_CRITICAL_P (e) && !(e->flags & EDGE_ABNORMAL))
4978 end_recording_case_labels ();
4981 struct tree_opt_pass pass_split_crit_edges =
4983 "crited", /* name */
4985 split_critical_edges, /* execute */
4988 0, /* static_pass_number */
4989 TV_TREE_SPLIT_EDGES, /* tv_id */
4990 PROP_cfg, /* properties required */
4991 PROP_no_crit_edges, /* properties_provided */
4992 0, /* properties_destroyed */
4993 0, /* todo_flags_start */
4994 TODO_dump_func, /* todo_flags_finish */
4999 /* Return EXP if it is a valid GIMPLE rvalue, else gimplify it into
5000 a temporary, make sure and register it to be renamed if necessary,
5001 and finally return the temporary. Put the statements to compute
5002 EXP before the current statement in BSI. */
5005 gimplify_val (block_stmt_iterator *bsi, tree type, tree exp)
5007 tree t, new_stmt, orig_stmt;
5009 if (is_gimple_val (exp))
5012 t = make_rename_temp (type, NULL);
5013 new_stmt = build (MODIFY_EXPR, type, t, exp);
5015 orig_stmt = bsi_stmt (*bsi);
5016 SET_EXPR_LOCUS (new_stmt, EXPR_LOCUS (orig_stmt));
5017 TREE_BLOCK (new_stmt) = TREE_BLOCK (orig_stmt);
5019 bsi_insert_before (bsi, new_stmt, BSI_SAME_STMT);
5024 /* Build a ternary operation and gimplify it. Emit code before BSI.
5025 Return the gimple_val holding the result. */
5028 gimplify_build3 (block_stmt_iterator *bsi, enum tree_code code,
5029 tree type, tree a, tree b, tree c)
5033 ret = fold_build3 (code, type, a, b, c);
5036 return gimplify_val (bsi, type, ret);
5039 /* Build a binary operation and gimplify it. Emit code before BSI.
5040 Return the gimple_val holding the result. */
5043 gimplify_build2 (block_stmt_iterator *bsi, enum tree_code code,
5044 tree type, tree a, tree b)
5048 ret = fold_build2 (code, type, a, b);
5051 return gimplify_val (bsi, type, ret);
5054 /* Build a unary operation and gimplify it. Emit code before BSI.
5055 Return the gimple_val holding the result. */
5058 gimplify_build1 (block_stmt_iterator *bsi, enum tree_code code, tree type,
5063 ret = fold_build1 (code, type, a);
5066 return gimplify_val (bsi, type, ret);
5071 /* Emit return warnings. */
5074 execute_warn_function_return (void)
5076 #ifdef USE_MAPPED_LOCATION
5077 source_location location;
5085 /* If we have a path to EXIT, then we do return. */
5086 if (TREE_THIS_VOLATILE (cfun->decl)
5087 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) > 0)
5089 #ifdef USE_MAPPED_LOCATION
5090 location = UNKNOWN_LOCATION;
5094 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
5096 last = last_stmt (e->src);
5097 if (TREE_CODE (last) == RETURN_EXPR
5098 #ifdef USE_MAPPED_LOCATION
5099 && (location = EXPR_LOCATION (last)) != UNKNOWN_LOCATION)
5101 && (locus = EXPR_LOCUS (last)) != NULL)
5105 #ifdef USE_MAPPED_LOCATION
5106 if (location == UNKNOWN_LOCATION)
5107 location = cfun->function_end_locus;
5108 warning (0, "%H%<noreturn%> function does return", &location);
5111 locus = &cfun->function_end_locus;
5112 warning (0, "%H%<noreturn%> function does return", locus);
5116 /* If we see "return;" in some basic block, then we do reach the end
5117 without returning a value. */
5118 else if (warn_return_type
5119 && !TREE_NO_WARNING (cfun->decl)
5120 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) > 0
5121 && !VOID_TYPE_P (TREE_TYPE (TREE_TYPE (cfun->decl))))
5123 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
5125 tree last = last_stmt (e->src);
5126 if (TREE_CODE (last) == RETURN_EXPR
5127 && TREE_OPERAND (last, 0) == NULL
5128 && !TREE_NO_WARNING (last))
5130 #ifdef USE_MAPPED_LOCATION
5131 location = EXPR_LOCATION (last);
5132 if (location == UNKNOWN_LOCATION)
5133 location = cfun->function_end_locus;
5134 warning (0, "%Hcontrol reaches end of non-void function", &location);
5136 locus = EXPR_LOCUS (last);
5138 locus = &cfun->function_end_locus;
5139 warning (0, "%Hcontrol reaches end of non-void function", locus);
5141 TREE_NO_WARNING (cfun->decl) = 1;
5149 /* Given a basic block B which ends with a conditional and has
5150 precisely two successors, determine which of the edges is taken if
5151 the conditional is true and which is taken if the conditional is
5152 false. Set TRUE_EDGE and FALSE_EDGE appropriately. */
5155 extract_true_false_edges_from_block (basic_block b,
5159 edge e = EDGE_SUCC (b, 0);
5161 if (e->flags & EDGE_TRUE_VALUE)
5164 *false_edge = EDGE_SUCC (b, 1);
5169 *true_edge = EDGE_SUCC (b, 1);
5173 struct tree_opt_pass pass_warn_function_return =
5177 execute_warn_function_return, /* execute */
5180 0, /* static_pass_number */
5182 PROP_cfg, /* properties_required */
5183 0, /* properties_provided */
5184 0, /* properties_destroyed */
5185 0, /* todo_flags_start */
5186 0, /* todo_flags_finish */
5190 /* Emit noreturn warnings. */
5193 execute_warn_function_noreturn (void)
5195 if (warn_missing_noreturn
5196 && !TREE_THIS_VOLATILE (cfun->decl)
5197 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) == 0
5198 && !lang_hooks.function.missing_noreturn_ok_p (cfun->decl))
5199 warning (OPT_Wmissing_noreturn, "%Jfunction might be possible candidate "
5200 "for attribute %<noreturn%>",
5204 struct tree_opt_pass pass_warn_function_noreturn =
5208 execute_warn_function_noreturn, /* execute */
5211 0, /* static_pass_number */
5213 PROP_cfg, /* properties_required */
5214 0, /* properties_provided */
5215 0, /* properties_destroyed */
5216 0, /* todo_flags_start */
5217 0, /* todo_flags_finish */