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;
582 gcc_assert (TREE_CODE (entry) == COND_EXPR);
584 /* Entry basic blocks for each component. */
585 then_label = GOTO_DESTINATION (COND_EXPR_THEN (entry));
586 else_label = GOTO_DESTINATION (COND_EXPR_ELSE (entry));
587 then_bb = label_to_block (then_label);
588 else_bb = label_to_block (else_label);
590 make_edge (bb, then_bb, EDGE_TRUE_VALUE);
591 make_edge (bb, else_bb, EDGE_FALSE_VALUE);
594 /* Hashing routine for EDGE_TO_CASES. */
597 edge_to_cases_hash (const void *p)
599 edge e = ((struct edge_to_cases_elt *)p)->e;
601 /* Hash on the edge itself (which is a pointer). */
602 return htab_hash_pointer (e);
605 /* Equality routine for EDGE_TO_CASES, edges are unique, so testing
606 for equality is just a pointer comparison. */
609 edge_to_cases_eq (const void *p1, const void *p2)
611 edge e1 = ((struct edge_to_cases_elt *)p1)->e;
612 edge e2 = ((struct edge_to_cases_elt *)p2)->e;
617 /* Called for each element in the hash table (P) as we delete the
618 edge to cases hash table.
620 Clear all the TREE_CHAINs to prevent problems with copying of
621 SWITCH_EXPRs and structure sharing rules, then free the hash table
625 edge_to_cases_cleanup (void *p)
627 struct edge_to_cases_elt *elt = p;
630 for (t = elt->case_labels; t; t = next)
632 next = TREE_CHAIN (t);
633 TREE_CHAIN (t) = NULL;
638 /* Start recording information mapping edges to case labels. */
641 start_recording_case_labels (void)
643 gcc_assert (edge_to_cases == NULL);
645 edge_to_cases = htab_create (37,
648 edge_to_cases_cleanup);
651 /* Return nonzero if we are recording information for case labels. */
654 recording_case_labels_p (void)
656 return (edge_to_cases != NULL);
659 /* Stop recording information mapping edges to case labels and
660 remove any information we have recorded. */
662 end_recording_case_labels (void)
664 htab_delete (edge_to_cases);
665 edge_to_cases = NULL;
668 /* Record that CASE_LABEL (a CASE_LABEL_EXPR) references edge E. */
671 record_switch_edge (edge e, tree case_label)
673 struct edge_to_cases_elt *elt;
676 /* Build a hash table element so we can see if E is already
678 elt = xmalloc (sizeof (struct edge_to_cases_elt));
680 elt->case_labels = case_label;
682 slot = htab_find_slot (edge_to_cases, elt, INSERT);
686 /* E was not in the hash table. Install E into the hash table. */
691 /* E was already in the hash table. Free ELT as we do not need it
695 /* Get the entry stored in the hash table. */
696 elt = (struct edge_to_cases_elt *) *slot;
698 /* Add it to the chain of CASE_LABEL_EXPRs referencing E. */
699 TREE_CHAIN (case_label) = elt->case_labels;
700 elt->case_labels = case_label;
704 /* If we are inside a {start,end}_recording_cases block, then return
705 a chain of CASE_LABEL_EXPRs from T which reference E.
707 Otherwise return NULL. */
710 get_cases_for_edge (edge e, tree t)
712 struct edge_to_cases_elt elt, *elt_p;
717 /* If we are not recording cases, then we do not have CASE_LABEL_EXPR
718 chains available. Return NULL so the caller can detect this case. */
719 if (!recording_case_labels_p ())
724 elt.case_labels = NULL;
725 slot = htab_find_slot (edge_to_cases, &elt, NO_INSERT);
729 elt_p = (struct edge_to_cases_elt *)*slot;
730 return elt_p->case_labels;
733 /* If we did not find E in the hash table, then this must be the first
734 time we have been queried for information about E & T. Add all the
735 elements from T to the hash table then perform the query again. */
737 vec = SWITCH_LABELS (t);
738 n = TREE_VEC_LENGTH (vec);
739 for (i = 0; i < n; i++)
741 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
742 basic_block label_bb = label_to_block (lab);
743 record_switch_edge (find_edge (e->src, label_bb), TREE_VEC_ELT (vec, i));
748 /* Create the edges for a SWITCH_EXPR starting at block BB.
749 At this point, the switch body has been lowered and the
750 SWITCH_LABELS filled in, so this is in effect a multi-way branch. */
753 make_switch_expr_edges (basic_block bb)
755 tree entry = last_stmt (bb);
759 vec = SWITCH_LABELS (entry);
760 n = TREE_VEC_LENGTH (vec);
762 for (i = 0; i < n; ++i)
764 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
765 basic_block label_bb = label_to_block (lab);
766 make_edge (bb, label_bb, 0);
771 /* Return the basic block holding label DEST. */
774 label_to_block_fn (struct function *ifun, tree dest)
776 int uid = LABEL_DECL_UID (dest);
778 /* We would die hard when faced by an undefined label. Emit a label to
779 the very first basic block. This will hopefully make even the dataflow
780 and undefined variable warnings quite right. */
781 if ((errorcount || sorrycount) && uid < 0)
783 block_stmt_iterator bsi = bsi_start (BASIC_BLOCK (0));
786 stmt = build1 (LABEL_EXPR, void_type_node, dest);
787 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
788 uid = LABEL_DECL_UID (dest);
790 if (VARRAY_SIZE (ifun->cfg->x_label_to_block_map) <= (unsigned int)uid)
792 return VARRAY_BB (ifun->cfg->x_label_to_block_map, uid);
795 /* Create edges for a goto statement at block BB. */
798 make_goto_expr_edges (basic_block bb)
801 basic_block target_bb;
803 block_stmt_iterator last = bsi_last (bb);
805 goto_t = bsi_stmt (last);
807 /* If the last statement is not a GOTO (i.e., it is a RETURN_EXPR,
808 CALL_EXPR or MODIFY_EXPR), then the edge is an abnormal edge resulting
809 from a nonlocal goto. */
810 if (TREE_CODE (goto_t) != GOTO_EXPR)
814 tree dest = GOTO_DESTINATION (goto_t);
817 /* A GOTO to a local label creates normal edges. */
818 if (simple_goto_p (goto_t))
820 edge e = make_edge (bb, label_to_block (dest), EDGE_FALLTHRU);
821 #ifdef USE_MAPPED_LOCATION
822 e->goto_locus = EXPR_LOCATION (goto_t);
824 e->goto_locus = EXPR_LOCUS (goto_t);
830 /* Nothing more to do for nonlocal gotos. */
831 if (TREE_CODE (dest) == LABEL_DECL)
834 /* Computed gotos remain. */
837 /* Look for the block starting with the destination label. In the
838 case of a computed goto, make an edge to any label block we find
840 FOR_EACH_BB (target_bb)
842 block_stmt_iterator bsi;
844 for (bsi = bsi_start (target_bb); !bsi_end_p (bsi); bsi_next (&bsi))
846 tree target = bsi_stmt (bsi);
848 if (TREE_CODE (target) != LABEL_EXPR)
852 /* Computed GOTOs. Make an edge to every label block that has
853 been marked as a potential target for a computed goto. */
854 (FORCED_LABEL (LABEL_EXPR_LABEL (target)) && for_call == 0)
855 /* Nonlocal GOTO target. Make an edge to every label block
856 that has been marked as a potential target for a nonlocal
858 || (DECL_NONLOCAL (LABEL_EXPR_LABEL (target)) && for_call == 1))
860 make_edge (bb, target_bb, EDGE_ABNORMAL);
866 /* Degenerate case of computed goto with no labels. */
867 if (!for_call && EDGE_COUNT (bb->succs) == 0)
868 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
872 /*---------------------------------------------------------------------------
874 ---------------------------------------------------------------------------*/
876 /* Cleanup useless labels in basic blocks. This is something we wish
877 to do early because it allows us to group case labels before creating
878 the edges for the CFG, and it speeds up block statement iterators in
880 We only run this pass once, running it more than once is probably not
883 /* A map from basic block index to the leading label of that block. */
884 static tree *label_for_bb;
886 /* Callback for for_each_eh_region. Helper for cleanup_dead_labels. */
888 update_eh_label (struct eh_region *region)
890 tree old_label = get_eh_region_tree_label (region);
894 basic_block bb = label_to_block (old_label);
896 /* ??? After optimizing, there may be EH regions with labels
897 that have already been removed from the function body, so
898 there is no basic block for them. */
902 new_label = label_for_bb[bb->index];
903 set_eh_region_tree_label (region, new_label);
907 /* Given LABEL return the first label in the same basic block. */
909 main_block_label (tree label)
911 basic_block bb = label_to_block (label);
913 /* label_to_block possibly inserted undefined label into the chain. */
914 if (!label_for_bb[bb->index])
915 label_for_bb[bb->index] = label;
916 return label_for_bb[bb->index];
919 /* Cleanup redundant labels. This is a three-step process:
920 1) Find the leading label for each block.
921 2) Redirect all references to labels to the leading labels.
922 3) Cleanup all useless labels. */
925 cleanup_dead_labels (void)
928 label_for_bb = xcalloc (last_basic_block, sizeof (tree));
930 /* Find a suitable label for each block. We use the first user-defined
931 label if there is one, or otherwise just the first label we see. */
934 block_stmt_iterator i;
936 for (i = bsi_start (bb); !bsi_end_p (i); bsi_next (&i))
938 tree label, stmt = bsi_stmt (i);
940 if (TREE_CODE (stmt) != LABEL_EXPR)
943 label = LABEL_EXPR_LABEL (stmt);
945 /* If we have not yet seen a label for the current block,
946 remember this one and see if there are more labels. */
947 if (! label_for_bb[bb->index])
949 label_for_bb[bb->index] = label;
953 /* If we did see a label for the current block already, but it
954 is an artificially created label, replace it if the current
955 label is a user defined label. */
956 if (! DECL_ARTIFICIAL (label)
957 && DECL_ARTIFICIAL (label_for_bb[bb->index]))
959 label_for_bb[bb->index] = label;
965 /* Now redirect all jumps/branches to the selected label.
966 First do so for each block ending in a control statement. */
969 tree stmt = last_stmt (bb);
973 switch (TREE_CODE (stmt))
977 tree true_branch, false_branch;
979 true_branch = COND_EXPR_THEN (stmt);
980 false_branch = COND_EXPR_ELSE (stmt);
982 GOTO_DESTINATION (true_branch)
983 = main_block_label (GOTO_DESTINATION (true_branch));
984 GOTO_DESTINATION (false_branch)
985 = main_block_label (GOTO_DESTINATION (false_branch));
993 tree vec = SWITCH_LABELS (stmt);
994 size_t n = TREE_VEC_LENGTH (vec);
996 /* Replace all destination labels. */
997 for (i = 0; i < n; ++i)
999 tree elt = TREE_VEC_ELT (vec, i);
1000 tree label = main_block_label (CASE_LABEL (elt));
1001 CASE_LABEL (elt) = label;
1006 /* We have to handle GOTO_EXPRs until they're removed, and we don't
1007 remove them until after we've created the CFG edges. */
1009 if (! computed_goto_p (stmt))
1011 GOTO_DESTINATION (stmt)
1012 = main_block_label (GOTO_DESTINATION (stmt));
1021 for_each_eh_region (update_eh_label);
1023 /* Finally, purge dead labels. All user-defined labels and labels that
1024 can be the target of non-local gotos are preserved. */
1027 block_stmt_iterator i;
1028 tree label_for_this_bb = label_for_bb[bb->index];
1030 if (! label_for_this_bb)
1033 for (i = bsi_start (bb); !bsi_end_p (i); )
1035 tree label, stmt = bsi_stmt (i);
1037 if (TREE_CODE (stmt) != LABEL_EXPR)
1040 label = LABEL_EXPR_LABEL (stmt);
1042 if (label == label_for_this_bb
1043 || ! DECL_ARTIFICIAL (label)
1044 || DECL_NONLOCAL (label))
1051 free (label_for_bb);
1054 /* Look for blocks ending in a multiway branch (a SWITCH_EXPR in GIMPLE),
1055 and scan the sorted vector of cases. Combine the ones jumping to the
1057 Eg. three separate entries 1: 2: 3: become one entry 1..3: */
1060 group_case_labels (void)
1066 tree stmt = last_stmt (bb);
1067 if (stmt && TREE_CODE (stmt) == SWITCH_EXPR)
1069 tree labels = SWITCH_LABELS (stmt);
1070 int old_size = TREE_VEC_LENGTH (labels);
1071 int i, j, new_size = old_size;
1072 tree default_case = TREE_VEC_ELT (labels, old_size - 1);
1075 /* The default label is always the last case in a switch
1076 statement after gimplification. */
1077 default_label = CASE_LABEL (default_case);
1079 /* Look for possible opportunities to merge cases.
1080 Ignore the last element of the label vector because it
1081 must be the default case. */
1083 while (i < old_size - 1)
1085 tree base_case, base_label, base_high;
1086 base_case = TREE_VEC_ELT (labels, i);
1088 gcc_assert (base_case);
1089 base_label = CASE_LABEL (base_case);
1091 /* Discard cases that have the same destination as the
1093 if (base_label == default_label)
1095 TREE_VEC_ELT (labels, i) = NULL_TREE;
1101 base_high = CASE_HIGH (base_case) ?
1102 CASE_HIGH (base_case) : CASE_LOW (base_case);
1104 /* Try to merge case labels. Break out when we reach the end
1105 of the label vector or when we cannot merge the next case
1106 label with the current one. */
1107 while (i < old_size - 1)
1109 tree merge_case = TREE_VEC_ELT (labels, i);
1110 tree merge_label = CASE_LABEL (merge_case);
1111 tree t = int_const_binop (PLUS_EXPR, base_high,
1112 integer_one_node, 1);
1114 /* Merge the cases if they jump to the same place,
1115 and their ranges are consecutive. */
1116 if (merge_label == base_label
1117 && tree_int_cst_equal (CASE_LOW (merge_case), t))
1119 base_high = CASE_HIGH (merge_case) ?
1120 CASE_HIGH (merge_case) : CASE_LOW (merge_case);
1121 CASE_HIGH (base_case) = base_high;
1122 TREE_VEC_ELT (labels, i) = NULL_TREE;
1131 /* Compress the case labels in the label vector, and adjust the
1132 length of the vector. */
1133 for (i = 0, j = 0; i < new_size; i++)
1135 while (! TREE_VEC_ELT (labels, j))
1137 TREE_VEC_ELT (labels, i) = TREE_VEC_ELT (labels, j++);
1139 TREE_VEC_LENGTH (labels) = new_size;
1144 /* Checks whether we can merge block B into block A. */
1147 tree_can_merge_blocks_p (basic_block a, basic_block b)
1150 block_stmt_iterator bsi;
1153 if (!single_succ_p (a))
1156 if (single_succ_edge (a)->flags & EDGE_ABNORMAL)
1159 if (single_succ (a) != b)
1162 if (!single_pred_p (b))
1165 if (b == EXIT_BLOCK_PTR)
1168 /* If A ends by a statement causing exceptions or something similar, we
1169 cannot merge the blocks. */
1170 stmt = last_stmt (a);
1171 if (stmt && stmt_ends_bb_p (stmt))
1174 /* Do not allow a block with only a non-local label to be merged. */
1175 if (stmt && TREE_CODE (stmt) == LABEL_EXPR
1176 && DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)))
1179 /* It must be possible to eliminate all phi nodes in B. If ssa form
1180 is not up-to-date, we cannot eliminate any phis. */
1181 phi = phi_nodes (b);
1184 if (need_ssa_update_p ())
1187 for (; phi; phi = PHI_CHAIN (phi))
1188 if (!is_gimple_reg (PHI_RESULT (phi))
1189 && !may_propagate_copy (PHI_RESULT (phi), PHI_ARG_DEF (phi, 0)))
1193 /* Do not remove user labels. */
1194 for (bsi = bsi_start (b); !bsi_end_p (bsi); bsi_next (&bsi))
1196 stmt = bsi_stmt (bsi);
1197 if (TREE_CODE (stmt) != LABEL_EXPR)
1199 if (!DECL_ARTIFICIAL (LABEL_EXPR_LABEL (stmt)))
1203 /* Protect the loop latches. */
1205 && b->loop_father->latch == b)
1211 /* Replaces all uses of NAME by VAL. */
1214 replace_uses_by (tree name, tree val)
1216 imm_use_iterator imm_iter;
1221 VEC(tree,heap) *stmts = VEC_alloc (tree, heap, 20);
1223 FOR_EACH_IMM_USE_SAFE (use, imm_iter, name)
1225 stmt = USE_STMT (use);
1229 if (TREE_CODE (stmt) == PHI_NODE)
1231 e = PHI_ARG_EDGE (stmt, PHI_ARG_INDEX_FROM_USE (use));
1232 if (e->flags & EDGE_ABNORMAL)
1234 /* This can only occur for virtual operands, since
1235 for the real ones SSA_NAME_OCCURS_IN_ABNORMAL_PHI (name))
1236 would prevent replacement. */
1237 gcc_assert (!is_gimple_reg (name));
1238 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (val) = 1;
1242 VEC_safe_push (tree, heap, stmts, stmt);
1245 /* We do not update the statements in the loop above. Consider
1248 If we performed the update in the first loop, the statement
1249 would be rescanned after first occurrence of w is replaced,
1250 the new uses would be placed to the beginning of the list,
1251 and we would never process them. */
1252 for (i = 0; VEC_iterate (tree, stmts, i, stmt); i++)
1256 fold_stmt_inplace (stmt);
1258 rhs = get_rhs (stmt);
1259 if (TREE_CODE (rhs) == ADDR_EXPR)
1260 recompute_tree_invarant_for_addr_expr (rhs);
1265 VEC_free (tree, heap, stmts);
1267 /* Also update the trees stored in loop structures. */
1272 for (i = 0; i < current_loops->num; i++)
1274 loop = current_loops->parray[i];
1276 substitute_in_loop_info (loop, name, val);
1281 /* Merge block B into block A. */
1284 tree_merge_blocks (basic_block a, basic_block b)
1286 block_stmt_iterator bsi;
1287 tree_stmt_iterator last;
1291 fprintf (dump_file, "Merging blocks %d and %d\n", a->index, b->index);
1293 /* Remove the phi nodes. */
1295 for (phi = phi_nodes (b); phi; phi = phi_nodes (b))
1297 tree def = PHI_RESULT (phi), use = PHI_ARG_DEF (phi, 0);
1300 if (!may_propagate_copy (def, use)
1301 /* Propagating pointers might cause the set of vops for statements
1302 to be changed, and thus require ssa form update. */
1303 || (is_gimple_reg (def)
1304 && POINTER_TYPE_P (TREE_TYPE (def))))
1306 gcc_assert (is_gimple_reg (def));
1308 /* Note that just emitting the copies is fine -- there is no problem
1309 with ordering of phi nodes. This is because A is the single
1310 predecessor of B, therefore results of the phi nodes cannot
1311 appear as arguments of the phi nodes. */
1312 copy = build2 (MODIFY_EXPR, void_type_node, def, use);
1313 bsi_insert_after (&bsi, copy, BSI_NEW_STMT);
1314 SET_PHI_RESULT (phi, NULL_TREE);
1315 SSA_NAME_DEF_STMT (def) = copy;
1318 replace_uses_by (def, use);
1319 remove_phi_node (phi, NULL);
1322 /* Ensure that B follows A. */
1323 move_block_after (b, a);
1325 gcc_assert (single_succ_edge (a)->flags & EDGE_FALLTHRU);
1326 gcc_assert (!last_stmt (a) || !stmt_ends_bb_p (last_stmt (a)));
1328 /* Remove labels from B and set bb_for_stmt to A for other statements. */
1329 for (bsi = bsi_start (b); !bsi_end_p (bsi);)
1331 if (TREE_CODE (bsi_stmt (bsi)) == LABEL_EXPR)
1333 tree label = bsi_stmt (bsi);
1336 /* Now that we can thread computed gotos, we might have
1337 a situation where we have a forced label in block B
1338 However, the label at the start of block B might still be
1339 used in other ways (think about the runtime checking for
1340 Fortran assigned gotos). So we can not just delete the
1341 label. Instead we move the label to the start of block A. */
1342 if (FORCED_LABEL (LABEL_EXPR_LABEL (label)))
1344 block_stmt_iterator dest_bsi = bsi_start (a);
1345 bsi_insert_before (&dest_bsi, label, BSI_NEW_STMT);
1350 set_bb_for_stmt (bsi_stmt (bsi), a);
1355 /* Merge the chains. */
1356 last = tsi_last (a->stmt_list);
1357 tsi_link_after (&last, b->stmt_list, TSI_NEW_STMT);
1358 b->stmt_list = NULL;
1362 /* Walk the function tree removing unnecessary statements.
1364 * Empty statement nodes are removed
1366 * Unnecessary TRY_FINALLY and TRY_CATCH blocks are removed
1368 * Unnecessary COND_EXPRs are removed
1370 * Some unnecessary BIND_EXPRs are removed
1372 Clearly more work could be done. The trick is doing the analysis
1373 and removal fast enough to be a net improvement in compile times.
1375 Note that when we remove a control structure such as a COND_EXPR
1376 BIND_EXPR, or TRY block, we will need to repeat this optimization pass
1377 to ensure we eliminate all the useless code. */
1388 static void remove_useless_stmts_1 (tree *, struct rus_data *);
1391 remove_useless_stmts_warn_notreached (tree stmt)
1393 if (EXPR_HAS_LOCATION (stmt))
1395 location_t loc = EXPR_LOCATION (stmt);
1396 if (LOCATION_LINE (loc) > 0)
1398 warning (0, "%Hwill never be executed", &loc);
1403 switch (TREE_CODE (stmt))
1405 case STATEMENT_LIST:
1407 tree_stmt_iterator i;
1408 for (i = tsi_start (stmt); !tsi_end_p (i); tsi_next (&i))
1409 if (remove_useless_stmts_warn_notreached (tsi_stmt (i)))
1415 if (remove_useless_stmts_warn_notreached (COND_EXPR_COND (stmt)))
1417 if (remove_useless_stmts_warn_notreached (COND_EXPR_THEN (stmt)))
1419 if (remove_useless_stmts_warn_notreached (COND_EXPR_ELSE (stmt)))
1423 case TRY_FINALLY_EXPR:
1424 case TRY_CATCH_EXPR:
1425 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt, 0)))
1427 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt, 1)))
1432 return remove_useless_stmts_warn_notreached (CATCH_BODY (stmt));
1433 case EH_FILTER_EXPR:
1434 return remove_useless_stmts_warn_notreached (EH_FILTER_FAILURE (stmt));
1436 return remove_useless_stmts_warn_notreached (BIND_EXPR_BLOCK (stmt));
1439 /* Not a live container. */
1447 remove_useless_stmts_cond (tree *stmt_p, struct rus_data *data)
1449 tree then_clause, else_clause, cond;
1450 bool save_has_label, then_has_label, else_has_label;
1452 save_has_label = data->has_label;
1453 data->has_label = false;
1454 data->last_goto = NULL;
1456 remove_useless_stmts_1 (&COND_EXPR_THEN (*stmt_p), data);
1458 then_has_label = data->has_label;
1459 data->has_label = false;
1460 data->last_goto = NULL;
1462 remove_useless_stmts_1 (&COND_EXPR_ELSE (*stmt_p), data);
1464 else_has_label = data->has_label;
1465 data->has_label = save_has_label | then_has_label | else_has_label;
1467 then_clause = COND_EXPR_THEN (*stmt_p);
1468 else_clause = COND_EXPR_ELSE (*stmt_p);
1469 cond = fold (COND_EXPR_COND (*stmt_p));
1471 /* If neither arm does anything at all, we can remove the whole IF. */
1472 if (!TREE_SIDE_EFFECTS (then_clause) && !TREE_SIDE_EFFECTS (else_clause))
1474 *stmt_p = build_empty_stmt ();
1475 data->repeat = true;
1478 /* If there are no reachable statements in an arm, then we can
1479 zap the entire conditional. */
1480 else if (integer_nonzerop (cond) && !else_has_label)
1482 if (warn_notreached)
1483 remove_useless_stmts_warn_notreached (else_clause);
1484 *stmt_p = then_clause;
1485 data->repeat = true;
1487 else if (integer_zerop (cond) && !then_has_label)
1489 if (warn_notreached)
1490 remove_useless_stmts_warn_notreached (then_clause);
1491 *stmt_p = else_clause;
1492 data->repeat = true;
1495 /* Check a couple of simple things on then/else with single stmts. */
1498 tree then_stmt = expr_only (then_clause);
1499 tree else_stmt = expr_only (else_clause);
1501 /* Notice branches to a common destination. */
1502 if (then_stmt && else_stmt
1503 && TREE_CODE (then_stmt) == GOTO_EXPR
1504 && TREE_CODE (else_stmt) == GOTO_EXPR
1505 && (GOTO_DESTINATION (then_stmt) == GOTO_DESTINATION (else_stmt)))
1507 *stmt_p = then_stmt;
1508 data->repeat = true;
1511 /* If the THEN/ELSE clause merely assigns a value to a variable or
1512 parameter which is already known to contain that value, then
1513 remove the useless THEN/ELSE clause. */
1514 else if (TREE_CODE (cond) == VAR_DECL || TREE_CODE (cond) == PARM_DECL)
1517 && TREE_CODE (else_stmt) == MODIFY_EXPR
1518 && TREE_OPERAND (else_stmt, 0) == cond
1519 && integer_zerop (TREE_OPERAND (else_stmt, 1)))
1520 COND_EXPR_ELSE (*stmt_p) = alloc_stmt_list ();
1522 else if ((TREE_CODE (cond) == EQ_EXPR || TREE_CODE (cond) == NE_EXPR)
1523 && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL
1524 || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL)
1525 && TREE_CONSTANT (TREE_OPERAND (cond, 1)))
1527 tree stmt = (TREE_CODE (cond) == EQ_EXPR
1528 ? then_stmt : else_stmt);
1529 tree *location = (TREE_CODE (cond) == EQ_EXPR
1530 ? &COND_EXPR_THEN (*stmt_p)
1531 : &COND_EXPR_ELSE (*stmt_p));
1534 && TREE_CODE (stmt) == MODIFY_EXPR
1535 && TREE_OPERAND (stmt, 0) == TREE_OPERAND (cond, 0)
1536 && TREE_OPERAND (stmt, 1) == TREE_OPERAND (cond, 1))
1537 *location = alloc_stmt_list ();
1541 /* Protect GOTOs in the arm of COND_EXPRs from being removed. They
1542 would be re-introduced during lowering. */
1543 data->last_goto = NULL;
1548 remove_useless_stmts_tf (tree *stmt_p, struct rus_data *data)
1550 bool save_may_branch, save_may_throw;
1551 bool this_may_branch, this_may_throw;
1553 /* Collect may_branch and may_throw information for the body only. */
1554 save_may_branch = data->may_branch;
1555 save_may_throw = data->may_throw;
1556 data->may_branch = false;
1557 data->may_throw = false;
1558 data->last_goto = NULL;
1560 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 0), data);
1562 this_may_branch = data->may_branch;
1563 this_may_throw = data->may_throw;
1564 data->may_branch |= save_may_branch;
1565 data->may_throw |= save_may_throw;
1566 data->last_goto = NULL;
1568 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 1), data);
1570 /* If the body is empty, then we can emit the FINALLY block without
1571 the enclosing TRY_FINALLY_EXPR. */
1572 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 0)))
1574 *stmt_p = TREE_OPERAND (*stmt_p, 1);
1575 data->repeat = true;
1578 /* If the handler is empty, then we can emit the TRY block without
1579 the enclosing TRY_FINALLY_EXPR. */
1580 else if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 1)))
1582 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1583 data->repeat = true;
1586 /* If the body neither throws, nor branches, then we can safely
1587 string the TRY and FINALLY blocks together. */
1588 else if (!this_may_branch && !this_may_throw)
1590 tree stmt = *stmt_p;
1591 *stmt_p = TREE_OPERAND (stmt, 0);
1592 append_to_statement_list (TREE_OPERAND (stmt, 1), stmt_p);
1593 data->repeat = true;
1599 remove_useless_stmts_tc (tree *stmt_p, struct rus_data *data)
1601 bool save_may_throw, this_may_throw;
1602 tree_stmt_iterator i;
1605 /* Collect may_throw information for the body only. */
1606 save_may_throw = data->may_throw;
1607 data->may_throw = false;
1608 data->last_goto = NULL;
1610 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 0), data);
1612 this_may_throw = data->may_throw;
1613 data->may_throw = save_may_throw;
1615 /* If the body cannot throw, then we can drop the entire TRY_CATCH_EXPR. */
1616 if (!this_may_throw)
1618 if (warn_notreached)
1619 remove_useless_stmts_warn_notreached (TREE_OPERAND (*stmt_p, 1));
1620 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1621 data->repeat = true;
1625 /* Process the catch clause specially. We may be able to tell that
1626 no exceptions propagate past this point. */
1628 this_may_throw = true;
1629 i = tsi_start (TREE_OPERAND (*stmt_p, 1));
1630 stmt = tsi_stmt (i);
1631 data->last_goto = NULL;
1633 switch (TREE_CODE (stmt))
1636 for (; !tsi_end_p (i); tsi_next (&i))
1638 stmt = tsi_stmt (i);
1639 /* If we catch all exceptions, then the body does not
1640 propagate exceptions past this point. */
1641 if (CATCH_TYPES (stmt) == NULL)
1642 this_may_throw = false;
1643 data->last_goto = NULL;
1644 remove_useless_stmts_1 (&CATCH_BODY (stmt), data);
1648 case EH_FILTER_EXPR:
1649 if (EH_FILTER_MUST_NOT_THROW (stmt))
1650 this_may_throw = false;
1651 else if (EH_FILTER_TYPES (stmt) == NULL)
1652 this_may_throw = false;
1653 remove_useless_stmts_1 (&EH_FILTER_FAILURE (stmt), data);
1657 /* Otherwise this is a cleanup. */
1658 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 1), data);
1660 /* If the cleanup is empty, then we can emit the TRY block without
1661 the enclosing TRY_CATCH_EXPR. */
1662 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 1)))
1664 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1665 data->repeat = true;
1669 data->may_throw |= this_may_throw;
1674 remove_useless_stmts_bind (tree *stmt_p, struct rus_data *data)
1678 /* First remove anything underneath the BIND_EXPR. */
1679 remove_useless_stmts_1 (&BIND_EXPR_BODY (*stmt_p), data);
1681 /* If the BIND_EXPR has no variables, then we can pull everything
1682 up one level and remove the BIND_EXPR, unless this is the toplevel
1683 BIND_EXPR for the current function or an inlined function.
1685 When this situation occurs we will want to apply this
1686 optimization again. */
1687 block = BIND_EXPR_BLOCK (*stmt_p);
1688 if (BIND_EXPR_VARS (*stmt_p) == NULL_TREE
1689 && *stmt_p != DECL_SAVED_TREE (current_function_decl)
1691 || ! BLOCK_ABSTRACT_ORIGIN (block)
1692 || (TREE_CODE (BLOCK_ABSTRACT_ORIGIN (block))
1695 *stmt_p = BIND_EXPR_BODY (*stmt_p);
1696 data->repeat = true;
1702 remove_useless_stmts_goto (tree *stmt_p, struct rus_data *data)
1704 tree dest = GOTO_DESTINATION (*stmt_p);
1706 data->may_branch = true;
1707 data->last_goto = NULL;
1709 /* Record the last goto expr, so that we can delete it if unnecessary. */
1710 if (TREE_CODE (dest) == LABEL_DECL)
1711 data->last_goto = stmt_p;
1716 remove_useless_stmts_label (tree *stmt_p, struct rus_data *data)
1718 tree label = LABEL_EXPR_LABEL (*stmt_p);
1720 data->has_label = true;
1722 /* We do want to jump across non-local label receiver code. */
1723 if (DECL_NONLOCAL (label))
1724 data->last_goto = NULL;
1726 else if (data->last_goto && GOTO_DESTINATION (*data->last_goto) == label)
1728 *data->last_goto = build_empty_stmt ();
1729 data->repeat = true;
1732 /* ??? Add something here to delete unused labels. */
1736 /* If the function is "const" or "pure", then clear TREE_SIDE_EFFECTS on its
1737 decl. This allows us to eliminate redundant or useless
1738 calls to "const" functions.
1740 Gimplifier already does the same operation, but we may notice functions
1741 being const and pure once their calls has been gimplified, so we need
1742 to update the flag. */
1745 update_call_expr_flags (tree call)
1747 tree decl = get_callee_fndecl (call);
1750 if (call_expr_flags (call) & (ECF_CONST | ECF_PURE))
1751 TREE_SIDE_EFFECTS (call) = 0;
1752 if (TREE_NOTHROW (decl))
1753 TREE_NOTHROW (call) = 1;
1757 /* T is CALL_EXPR. Set current_function_calls_* flags. */
1760 notice_special_calls (tree t)
1762 int flags = call_expr_flags (t);
1764 if (flags & ECF_MAY_BE_ALLOCA)
1765 current_function_calls_alloca = true;
1766 if (flags & ECF_RETURNS_TWICE)
1767 current_function_calls_setjmp = true;
1771 /* Clear flags set by notice_special_calls. Used by dead code removal
1772 to update the flags. */
1775 clear_special_calls (void)
1777 current_function_calls_alloca = false;
1778 current_function_calls_setjmp = false;
1783 remove_useless_stmts_1 (tree *tp, struct rus_data *data)
1787 switch (TREE_CODE (t))
1790 remove_useless_stmts_cond (tp, data);
1793 case TRY_FINALLY_EXPR:
1794 remove_useless_stmts_tf (tp, data);
1797 case TRY_CATCH_EXPR:
1798 remove_useless_stmts_tc (tp, data);
1802 remove_useless_stmts_bind (tp, data);
1806 remove_useless_stmts_goto (tp, data);
1810 remove_useless_stmts_label (tp, data);
1815 data->last_goto = NULL;
1816 data->may_branch = true;
1821 data->last_goto = NULL;
1822 notice_special_calls (t);
1823 update_call_expr_flags (t);
1824 if (tree_could_throw_p (t))
1825 data->may_throw = true;
1829 data->last_goto = NULL;
1831 op = get_call_expr_in (t);
1834 update_call_expr_flags (op);
1835 notice_special_calls (op);
1837 if (tree_could_throw_p (t))
1838 data->may_throw = true;
1841 case STATEMENT_LIST:
1843 tree_stmt_iterator i = tsi_start (t);
1844 while (!tsi_end_p (i))
1847 if (IS_EMPTY_STMT (t))
1853 remove_useless_stmts_1 (tsi_stmt_ptr (i), data);
1856 if (TREE_CODE (t) == STATEMENT_LIST)
1858 tsi_link_before (&i, t, TSI_SAME_STMT);
1868 data->last_goto = NULL;
1872 data->last_goto = NULL;
1878 remove_useless_stmts (void)
1880 struct rus_data data;
1882 clear_special_calls ();
1886 memset (&data, 0, sizeof (data));
1887 remove_useless_stmts_1 (&DECL_SAVED_TREE (current_function_decl), &data);
1889 while (data.repeat);
1893 struct tree_opt_pass pass_remove_useless_stmts =
1895 "useless", /* name */
1897 remove_useless_stmts, /* execute */
1900 0, /* static_pass_number */
1902 PROP_gimple_any, /* properties_required */
1903 0, /* properties_provided */
1904 0, /* properties_destroyed */
1905 0, /* todo_flags_start */
1906 TODO_dump_func, /* todo_flags_finish */
1910 /* Remove PHI nodes associated with basic block BB and all edges out of BB. */
1913 remove_phi_nodes_and_edges_for_unreachable_block (basic_block bb)
1917 /* Since this block is no longer reachable, we can just delete all
1918 of its PHI nodes. */
1919 phi = phi_nodes (bb);
1922 tree next = PHI_CHAIN (phi);
1923 remove_phi_node (phi, NULL_TREE);
1927 /* Remove edges to BB's successors. */
1928 while (EDGE_COUNT (bb->succs) > 0)
1929 remove_edge (EDGE_SUCC (bb, 0));
1933 /* Remove statements of basic block BB. */
1936 remove_bb (basic_block bb)
1938 block_stmt_iterator i;
1939 #ifdef USE_MAPPED_LOCATION
1940 source_location loc = UNKNOWN_LOCATION;
1942 source_locus loc = 0;
1947 fprintf (dump_file, "Removing basic block %d\n", bb->index);
1948 if (dump_flags & TDF_DETAILS)
1950 dump_bb (bb, dump_file, 0);
1951 fprintf (dump_file, "\n");
1955 /* If we remove the header or the latch of a loop, mark the loop for
1956 removal by setting its header and latch to NULL. */
1959 struct loop *loop = bb->loop_father;
1961 if (loop->latch == bb
1962 || loop->header == bb)
1965 loop->header = NULL;
1969 /* Remove all the instructions in the block. */
1970 for (i = bsi_start (bb); !bsi_end_p (i);)
1972 tree stmt = bsi_stmt (i);
1973 if (TREE_CODE (stmt) == LABEL_EXPR
1974 && FORCED_LABEL (LABEL_EXPR_LABEL (stmt)))
1976 basic_block new_bb = bb->prev_bb;
1977 block_stmt_iterator new_bsi = bsi_start (new_bb);
1980 bsi_insert_before (&new_bsi, stmt, BSI_NEW_STMT);
1984 /* Release SSA definitions if we are in SSA. Note that we
1985 may be called when not in SSA. For example,
1986 final_cleanup calls this function via
1987 cleanup_tree_cfg. */
1989 release_defs (stmt);
1994 /* Don't warn for removed gotos. Gotos are often removed due to
1995 jump threading, thus resulting in bogus warnings. Not great,
1996 since this way we lose warnings for gotos in the original
1997 program that are indeed unreachable. */
1998 if (TREE_CODE (stmt) != GOTO_EXPR && EXPR_HAS_LOCATION (stmt) && !loc)
2000 #ifdef USE_MAPPED_LOCATION
2001 if (EXPR_HAS_LOCATION (stmt))
2002 loc = EXPR_LOCATION (stmt);
2005 t = EXPR_LOCUS (stmt);
2006 if (t && LOCATION_LINE (*t) > 0)
2012 /* If requested, give a warning that the first statement in the
2013 block is unreachable. We walk statements backwards in the
2014 loop above, so the last statement we process is the first statement
2016 #ifdef USE_MAPPED_LOCATION
2017 if (loc > BUILTINS_LOCATION)
2018 warning (OPT_Wunreachable_code, "%Hwill never be executed", &loc);
2021 warning (OPT_Wunreachable_code, "%Hwill never be executed", loc);
2024 remove_phi_nodes_and_edges_for_unreachable_block (bb);
2028 /* Given a basic block BB ending with COND_EXPR or SWITCH_EXPR, and a
2029 predicate VAL, return the edge that will be taken out of the block.
2030 If VAL does not match a unique edge, NULL is returned. */
2033 find_taken_edge (basic_block bb, tree val)
2037 stmt = last_stmt (bb);
2040 gcc_assert (is_ctrl_stmt (stmt));
2043 if (! is_gimple_min_invariant (val))
2046 if (TREE_CODE (stmt) == COND_EXPR)
2047 return find_taken_edge_cond_expr (bb, val);
2049 if (TREE_CODE (stmt) == SWITCH_EXPR)
2050 return find_taken_edge_switch_expr (bb, val);
2052 if (computed_goto_p (stmt))
2053 return find_taken_edge_computed_goto (bb, TREE_OPERAND( val, 0));
2058 /* Given a constant value VAL and the entry block BB to a GOTO_EXPR
2059 statement, determine which of the outgoing edges will be taken out of the
2060 block. Return NULL if either edge may be taken. */
2063 find_taken_edge_computed_goto (basic_block bb, tree val)
2068 dest = label_to_block (val);
2071 e = find_edge (bb, dest);
2072 gcc_assert (e != NULL);
2078 /* Given a constant value VAL and the entry block BB to a COND_EXPR
2079 statement, determine which of the two edges will be taken out of the
2080 block. Return NULL if either edge may be taken. */
2083 find_taken_edge_cond_expr (basic_block bb, tree val)
2085 edge true_edge, false_edge;
2087 extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
2089 gcc_assert (TREE_CODE (val) == INTEGER_CST);
2090 return (zero_p (val) ? false_edge : true_edge);
2093 /* Given an INTEGER_CST VAL and the entry block BB to a SWITCH_EXPR
2094 statement, determine which edge will be taken out of the block. Return
2095 NULL if any edge may be taken. */
2098 find_taken_edge_switch_expr (basic_block bb, tree val)
2100 tree switch_expr, taken_case;
2101 basic_block dest_bb;
2104 switch_expr = last_stmt (bb);
2105 taken_case = find_case_label_for_value (switch_expr, val);
2106 dest_bb = label_to_block (CASE_LABEL (taken_case));
2108 e = find_edge (bb, dest_bb);
2114 /* Return the CASE_LABEL_EXPR that SWITCH_EXPR will take for VAL.
2115 We can make optimal use here of the fact that the case labels are
2116 sorted: We can do a binary search for a case matching VAL. */
2119 find_case_label_for_value (tree switch_expr, tree val)
2121 tree vec = SWITCH_LABELS (switch_expr);
2122 size_t low, high, n = TREE_VEC_LENGTH (vec);
2123 tree default_case = TREE_VEC_ELT (vec, n - 1);
2125 for (low = -1, high = n - 1; high - low > 1; )
2127 size_t i = (high + low) / 2;
2128 tree t = TREE_VEC_ELT (vec, i);
2131 /* Cache the result of comparing CASE_LOW and val. */
2132 cmp = tree_int_cst_compare (CASE_LOW (t), val);
2139 if (CASE_HIGH (t) == NULL)
2141 /* A singe-valued case label. */
2147 /* A case range. We can only handle integer ranges. */
2148 if (cmp <= 0 && tree_int_cst_compare (CASE_HIGH (t), val) >= 0)
2153 return default_case;
2159 /*---------------------------------------------------------------------------
2161 ---------------------------------------------------------------------------*/
2163 /* Dump tree-specific information of block BB to file OUTF. */
2166 tree_dump_bb (basic_block bb, FILE *outf, int indent)
2168 dump_generic_bb (outf, bb, indent, TDF_VOPS);
2172 /* Dump a basic block on stderr. */
2175 debug_tree_bb (basic_block bb)
2177 dump_bb (bb, stderr, 0);
2181 /* Dump basic block with index N on stderr. */
2184 debug_tree_bb_n (int n)
2186 debug_tree_bb (BASIC_BLOCK (n));
2187 return BASIC_BLOCK (n);
2191 /* Dump the CFG on stderr.
2193 FLAGS are the same used by the tree dumping functions
2194 (see TDF_* in tree.h). */
2197 debug_tree_cfg (int flags)
2199 dump_tree_cfg (stderr, flags);
2203 /* Dump the program showing basic block boundaries on the given FILE.
2205 FLAGS are the same used by the tree dumping functions (see TDF_* in
2209 dump_tree_cfg (FILE *file, int flags)
2211 if (flags & TDF_DETAILS)
2213 const char *funcname
2214 = lang_hooks.decl_printable_name (current_function_decl, 2);
2217 fprintf (file, ";; Function %s\n\n", funcname);
2218 fprintf (file, ";; \n%d basic blocks, %d edges, last basic block %d.\n\n",
2219 n_basic_blocks, n_edges, last_basic_block);
2221 brief_dump_cfg (file);
2222 fprintf (file, "\n");
2225 if (flags & TDF_STATS)
2226 dump_cfg_stats (file);
2228 dump_function_to_file (current_function_decl, file, flags | TDF_BLOCKS);
2232 /* Dump CFG statistics on FILE. */
2235 dump_cfg_stats (FILE *file)
2237 static long max_num_merged_labels = 0;
2238 unsigned long size, total = 0;
2241 const char * const fmt_str = "%-30s%-13s%12s\n";
2242 const char * const fmt_str_1 = "%-30s%13d%11lu%c\n";
2243 const char * const fmt_str_3 = "%-43s%11lu%c\n";
2244 const char *funcname
2245 = lang_hooks.decl_printable_name (current_function_decl, 2);
2248 fprintf (file, "\nCFG Statistics for %s\n\n", funcname);
2250 fprintf (file, "---------------------------------------------------------\n");
2251 fprintf (file, fmt_str, "", " Number of ", "Memory");
2252 fprintf (file, fmt_str, "", " instances ", "used ");
2253 fprintf (file, "---------------------------------------------------------\n");
2255 size = n_basic_blocks * sizeof (struct basic_block_def);
2257 fprintf (file, fmt_str_1, "Basic blocks", n_basic_blocks,
2258 SCALE (size), LABEL (size));
2262 num_edges += EDGE_COUNT (bb->succs);
2263 size = num_edges * sizeof (struct edge_def);
2265 fprintf (file, fmt_str_1, "Edges", num_edges, SCALE (size), LABEL (size));
2267 fprintf (file, "---------------------------------------------------------\n");
2268 fprintf (file, fmt_str_3, "Total memory used by CFG data", SCALE (total),
2270 fprintf (file, "---------------------------------------------------------\n");
2271 fprintf (file, "\n");
2273 if (cfg_stats.num_merged_labels > max_num_merged_labels)
2274 max_num_merged_labels = cfg_stats.num_merged_labels;
2276 fprintf (file, "Coalesced label blocks: %ld (Max so far: %ld)\n",
2277 cfg_stats.num_merged_labels, max_num_merged_labels);
2279 fprintf (file, "\n");
2283 /* Dump CFG statistics on stderr. Keep extern so that it's always
2284 linked in the final executable. */
2287 debug_cfg_stats (void)
2289 dump_cfg_stats (stderr);
2293 /* Dump the flowgraph to a .vcg FILE. */
2296 tree_cfg2vcg (FILE *file)
2301 const char *funcname
2302 = lang_hooks.decl_printable_name (current_function_decl, 2);
2304 /* Write the file header. */
2305 fprintf (file, "graph: { title: \"%s\"\n", funcname);
2306 fprintf (file, "node: { title: \"ENTRY\" label: \"ENTRY\" }\n");
2307 fprintf (file, "node: { title: \"EXIT\" label: \"EXIT\" }\n");
2309 /* Write blocks and edges. */
2310 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
2312 fprintf (file, "edge: { sourcename: \"ENTRY\" targetname: \"%d\"",
2315 if (e->flags & EDGE_FAKE)
2316 fprintf (file, " linestyle: dotted priority: 10");
2318 fprintf (file, " linestyle: solid priority: 100");
2320 fprintf (file, " }\n");
2326 enum tree_code head_code, end_code;
2327 const char *head_name, *end_name;
2330 tree first = first_stmt (bb);
2331 tree last = last_stmt (bb);
2335 head_code = TREE_CODE (first);
2336 head_name = tree_code_name[head_code];
2337 head_line = get_lineno (first);
2340 head_name = "no-statement";
2344 end_code = TREE_CODE (last);
2345 end_name = tree_code_name[end_code];
2346 end_line = get_lineno (last);
2349 end_name = "no-statement";
2351 fprintf (file, "node: { title: \"%d\" label: \"#%d\\n%s (%d)\\n%s (%d)\"}\n",
2352 bb->index, bb->index, head_name, head_line, end_name,
2355 FOR_EACH_EDGE (e, ei, bb->succs)
2357 if (e->dest == EXIT_BLOCK_PTR)
2358 fprintf (file, "edge: { sourcename: \"%d\" targetname: \"EXIT\"", bb->index);
2360 fprintf (file, "edge: { sourcename: \"%d\" targetname: \"%d\"", bb->index, e->dest->index);
2362 if (e->flags & EDGE_FAKE)
2363 fprintf (file, " priority: 10 linestyle: dotted");
2365 fprintf (file, " priority: 100 linestyle: solid");
2367 fprintf (file, " }\n");
2370 if (bb->next_bb != EXIT_BLOCK_PTR)
2374 fputs ("}\n\n", file);
2379 /*---------------------------------------------------------------------------
2380 Miscellaneous helpers
2381 ---------------------------------------------------------------------------*/
2383 /* Return true if T represents a stmt that always transfers control. */
2386 is_ctrl_stmt (tree t)
2388 return (TREE_CODE (t) == COND_EXPR
2389 || TREE_CODE (t) == SWITCH_EXPR
2390 || TREE_CODE (t) == GOTO_EXPR
2391 || TREE_CODE (t) == RETURN_EXPR
2392 || TREE_CODE (t) == RESX_EXPR);
2396 /* Return true if T is a statement that may alter the flow of control
2397 (e.g., a call to a non-returning function). */
2400 is_ctrl_altering_stmt (tree t)
2405 call = get_call_expr_in (t);
2408 /* A non-pure/const CALL_EXPR alters flow control if the current
2409 function has nonlocal labels. */
2410 if (TREE_SIDE_EFFECTS (call) && current_function_has_nonlocal_label)
2413 /* A CALL_EXPR also alters control flow if it does not return. */
2414 if (call_expr_flags (call) & ECF_NORETURN)
2418 /* If a statement can throw, it alters control flow. */
2419 return tree_can_throw_internal (t);
2423 /* Return true if T is a computed goto. */
2426 computed_goto_p (tree t)
2428 return (TREE_CODE (t) == GOTO_EXPR
2429 && TREE_CODE (GOTO_DESTINATION (t)) != LABEL_DECL);
2433 /* Checks whether EXPR is a simple local goto. */
2436 simple_goto_p (tree expr)
2438 return (TREE_CODE (expr) == GOTO_EXPR
2439 && TREE_CODE (GOTO_DESTINATION (expr)) == LABEL_DECL);
2443 /* Return true if T should start a new basic block. PREV_T is the
2444 statement preceding T. It is used when T is a label or a case label.
2445 Labels should only start a new basic block if their previous statement
2446 wasn't a label. Otherwise, sequence of labels would generate
2447 unnecessary basic blocks that only contain a single label. */
2450 stmt_starts_bb_p (tree t, tree prev_t)
2455 /* LABEL_EXPRs start a new basic block only if the preceding
2456 statement wasn't a label of the same type. This prevents the
2457 creation of consecutive blocks that have nothing but a single
2459 if (TREE_CODE (t) == LABEL_EXPR)
2461 /* Nonlocal and computed GOTO targets always start a new block. */
2462 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (t))
2463 || FORCED_LABEL (LABEL_EXPR_LABEL (t)))
2466 if (prev_t && TREE_CODE (prev_t) == LABEL_EXPR)
2468 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (prev_t)))
2471 cfg_stats.num_merged_labels++;
2482 /* Return true if T should end a basic block. */
2485 stmt_ends_bb_p (tree t)
2487 return is_ctrl_stmt (t) || is_ctrl_altering_stmt (t);
2491 /* Add gotos that used to be represented implicitly in the CFG. */
2494 disband_implicit_edges (void)
2497 block_stmt_iterator last;
2504 last = bsi_last (bb);
2505 stmt = last_stmt (bb);
2507 if (stmt && TREE_CODE (stmt) == COND_EXPR)
2509 /* Remove superfluous gotos from COND_EXPR branches. Moved
2510 from cfg_remove_useless_stmts here since it violates the
2511 invariants for tree--cfg correspondence and thus fits better
2512 here where we do it anyway. */
2513 e = find_edge (bb, bb->next_bb);
2516 if (e->flags & EDGE_TRUE_VALUE)
2517 COND_EXPR_THEN (stmt) = build_empty_stmt ();
2518 else if (e->flags & EDGE_FALSE_VALUE)
2519 COND_EXPR_ELSE (stmt) = build_empty_stmt ();
2522 e->flags |= EDGE_FALLTHRU;
2528 if (stmt && TREE_CODE (stmt) == RETURN_EXPR)
2530 /* Remove the RETURN_EXPR if we may fall though to the exit
2532 gcc_assert (single_succ_p (bb));
2533 gcc_assert (single_succ (bb) == EXIT_BLOCK_PTR);
2535 if (bb->next_bb == EXIT_BLOCK_PTR
2536 && !TREE_OPERAND (stmt, 0))
2539 single_succ_edge (bb)->flags |= EDGE_FALLTHRU;
2544 /* There can be no fallthru edge if the last statement is a control
2546 if (stmt && is_ctrl_stmt (stmt))
2549 /* Find a fallthru edge and emit the goto if necessary. */
2550 FOR_EACH_EDGE (e, ei, bb->succs)
2551 if (e->flags & EDGE_FALLTHRU)
2554 if (!e || e->dest == bb->next_bb)
2557 gcc_assert (e->dest != EXIT_BLOCK_PTR);
2558 label = tree_block_label (e->dest);
2560 stmt = build1 (GOTO_EXPR, void_type_node, label);
2561 #ifdef USE_MAPPED_LOCATION
2562 SET_EXPR_LOCATION (stmt, e->goto_locus);
2564 SET_EXPR_LOCUS (stmt, e->goto_locus);
2566 bsi_insert_after (&last, stmt, BSI_NEW_STMT);
2567 e->flags &= ~EDGE_FALLTHRU;
2571 /* Remove block annotations and other datastructures. */
2574 delete_tree_cfg_annotations (void)
2576 label_to_block_map = NULL;
2580 /* Return the first statement in basic block BB. */
2583 first_stmt (basic_block bb)
2585 block_stmt_iterator i = bsi_start (bb);
2586 return !bsi_end_p (i) ? bsi_stmt (i) : NULL_TREE;
2590 /* Return the last statement in basic block BB. */
2593 last_stmt (basic_block bb)
2595 block_stmt_iterator b = bsi_last (bb);
2596 return !bsi_end_p (b) ? bsi_stmt (b) : NULL_TREE;
2600 /* Return a pointer to the last statement in block BB. */
2603 last_stmt_ptr (basic_block bb)
2605 block_stmt_iterator last = bsi_last (bb);
2606 return !bsi_end_p (last) ? bsi_stmt_ptr (last) : NULL;
2610 /* Return the last statement of an otherwise empty block. Return NULL
2611 if the block is totally empty, or if it contains more than one
2615 last_and_only_stmt (basic_block bb)
2617 block_stmt_iterator i = bsi_last (bb);
2623 last = bsi_stmt (i);
2628 /* Empty statements should no longer appear in the instruction stream.
2629 Everything that might have appeared before should be deleted by
2630 remove_useless_stmts, and the optimizers should just bsi_remove
2631 instead of smashing with build_empty_stmt.
2633 Thus the only thing that should appear here in a block containing
2634 one executable statement is a label. */
2635 prev = bsi_stmt (i);
2636 if (TREE_CODE (prev) == LABEL_EXPR)
2643 /* Mark BB as the basic block holding statement T. */
2646 set_bb_for_stmt (tree t, basic_block bb)
2648 if (TREE_CODE (t) == PHI_NODE)
2650 else if (TREE_CODE (t) == STATEMENT_LIST)
2652 tree_stmt_iterator i;
2653 for (i = tsi_start (t); !tsi_end_p (i); tsi_next (&i))
2654 set_bb_for_stmt (tsi_stmt (i), bb);
2658 stmt_ann_t ann = get_stmt_ann (t);
2661 /* If the statement is a label, add the label to block-to-labels map
2662 so that we can speed up edge creation for GOTO_EXPRs. */
2663 if (TREE_CODE (t) == LABEL_EXPR)
2667 t = LABEL_EXPR_LABEL (t);
2668 uid = LABEL_DECL_UID (t);
2671 LABEL_DECL_UID (t) = uid = cfun->last_label_uid++;
2672 if (VARRAY_SIZE (label_to_block_map) <= (unsigned) uid)
2673 VARRAY_GROW (label_to_block_map, 3 * uid / 2);
2676 /* We're moving an existing label. Make sure that we've
2677 removed it from the old block. */
2678 gcc_assert (!bb || !VARRAY_BB (label_to_block_map, uid));
2679 VARRAY_BB (label_to_block_map, uid) = bb;
2684 /* Finds iterator for STMT. */
2686 extern block_stmt_iterator
2687 bsi_for_stmt (tree stmt)
2689 block_stmt_iterator bsi;
2691 for (bsi = bsi_start (bb_for_stmt (stmt)); !bsi_end_p (bsi); bsi_next (&bsi))
2692 if (bsi_stmt (bsi) == stmt)
2698 /* Mark statement T as modified, and update it. */
2700 update_modified_stmts (tree t)
2702 if (TREE_CODE (t) == STATEMENT_LIST)
2704 tree_stmt_iterator i;
2706 for (i = tsi_start (t); !tsi_end_p (i); tsi_next (&i))
2708 stmt = tsi_stmt (i);
2709 update_stmt_if_modified (stmt);
2713 update_stmt_if_modified (t);
2716 /* Insert statement (or statement list) T before the statement
2717 pointed-to by iterator I. M specifies how to update iterator I
2718 after insertion (see enum bsi_iterator_update). */
2721 bsi_insert_before (block_stmt_iterator *i, tree t, enum bsi_iterator_update m)
2723 set_bb_for_stmt (t, i->bb);
2724 update_modified_stmts (t);
2725 tsi_link_before (&i->tsi, t, m);
2729 /* Insert statement (or statement list) T after the statement
2730 pointed-to by iterator I. M specifies how to update iterator I
2731 after insertion (see enum bsi_iterator_update). */
2734 bsi_insert_after (block_stmt_iterator *i, tree t, enum bsi_iterator_update m)
2736 set_bb_for_stmt (t, i->bb);
2737 update_modified_stmts (t);
2738 tsi_link_after (&i->tsi, t, m);
2742 /* Remove the statement pointed to by iterator I. The iterator is updated
2743 to the next statement. */
2746 bsi_remove (block_stmt_iterator *i)
2748 tree t = bsi_stmt (*i);
2749 set_bb_for_stmt (t, NULL);
2750 delink_stmt_imm_use (t);
2751 tsi_delink (&i->tsi);
2752 mark_stmt_modified (t);
2756 /* Move the statement at FROM so it comes right after the statement at TO. */
2759 bsi_move_after (block_stmt_iterator *from, block_stmt_iterator *to)
2761 tree stmt = bsi_stmt (*from);
2763 bsi_insert_after (to, stmt, BSI_SAME_STMT);
2767 /* Move the statement at FROM so it comes right before the statement at TO. */
2770 bsi_move_before (block_stmt_iterator *from, block_stmt_iterator *to)
2772 tree stmt = bsi_stmt (*from);
2774 bsi_insert_before (to, stmt, BSI_SAME_STMT);
2778 /* Move the statement at FROM to the end of basic block BB. */
2781 bsi_move_to_bb_end (block_stmt_iterator *from, basic_block bb)
2783 block_stmt_iterator last = bsi_last (bb);
2785 /* Have to check bsi_end_p because it could be an empty block. */
2786 if (!bsi_end_p (last) && is_ctrl_stmt (bsi_stmt (last)))
2787 bsi_move_before (from, &last);
2789 bsi_move_after (from, &last);
2793 /* Replace the contents of the statement pointed to by iterator BSI
2794 with STMT. If PRESERVE_EH_INFO is true, the exception handling
2795 information of the original statement is preserved. */
2798 bsi_replace (const block_stmt_iterator *bsi, tree stmt, bool preserve_eh_info)
2801 tree orig_stmt = bsi_stmt (*bsi);
2803 SET_EXPR_LOCUS (stmt, EXPR_LOCUS (orig_stmt));
2804 set_bb_for_stmt (stmt, bsi->bb);
2806 /* Preserve EH region information from the original statement, if
2807 requested by the caller. */
2808 if (preserve_eh_info)
2810 eh_region = lookup_stmt_eh_region (orig_stmt);
2812 add_stmt_to_eh_region (stmt, eh_region);
2815 delink_stmt_imm_use (orig_stmt);
2816 *bsi_stmt_ptr (*bsi) = stmt;
2817 mark_stmt_modified (stmt);
2818 update_modified_stmts (stmt);
2822 /* Insert the statement pointed-to by BSI into edge E. Every attempt
2823 is made to place the statement in an existing basic block, but
2824 sometimes that isn't possible. When it isn't possible, the edge is
2825 split and the statement is added to the new block.
2827 In all cases, the returned *BSI points to the correct location. The
2828 return value is true if insertion should be done after the location,
2829 or false if it should be done before the location. If new basic block
2830 has to be created, it is stored in *NEW_BB. */
2833 tree_find_edge_insert_loc (edge e, block_stmt_iterator *bsi,
2834 basic_block *new_bb)
2836 basic_block dest, src;
2842 /* If the destination has one predecessor which has no PHI nodes,
2843 insert there. Except for the exit block.
2845 The requirement for no PHI nodes could be relaxed. Basically we
2846 would have to examine the PHIs to prove that none of them used
2847 the value set by the statement we want to insert on E. That
2848 hardly seems worth the effort. */
2849 if (single_pred_p (dest)
2850 && ! phi_nodes (dest)
2851 && dest != EXIT_BLOCK_PTR)
2853 *bsi = bsi_start (dest);
2854 if (bsi_end_p (*bsi))
2857 /* Make sure we insert after any leading labels. */
2858 tmp = bsi_stmt (*bsi);
2859 while (TREE_CODE (tmp) == LABEL_EXPR)
2862 if (bsi_end_p (*bsi))
2864 tmp = bsi_stmt (*bsi);
2867 if (bsi_end_p (*bsi))
2869 *bsi = bsi_last (dest);
2876 /* If the source has one successor, the edge is not abnormal and
2877 the last statement does not end a basic block, insert there.
2878 Except for the entry block. */
2880 if ((e->flags & EDGE_ABNORMAL) == 0
2881 && single_succ_p (src)
2882 && src != ENTRY_BLOCK_PTR)
2884 *bsi = bsi_last (src);
2885 if (bsi_end_p (*bsi))
2888 tmp = bsi_stmt (*bsi);
2889 if (!stmt_ends_bb_p (tmp))
2892 /* Insert code just before returning the value. We may need to decompose
2893 the return in the case it contains non-trivial operand. */
2894 if (TREE_CODE (tmp) == RETURN_EXPR)
2896 tree op = TREE_OPERAND (tmp, 0);
2897 if (!is_gimple_val (op))
2899 gcc_assert (TREE_CODE (op) == MODIFY_EXPR);
2900 bsi_insert_before (bsi, op, BSI_NEW_STMT);
2901 TREE_OPERAND (tmp, 0) = TREE_OPERAND (op, 0);
2908 /* Otherwise, create a new basic block, and split this edge. */
2909 dest = split_edge (e);
2912 e = single_pred_edge (dest);
2917 /* This routine will commit all pending edge insertions, creating any new
2918 basic blocks which are necessary. */
2921 bsi_commit_edge_inserts (void)
2927 bsi_commit_one_edge_insert (single_succ_edge (ENTRY_BLOCK_PTR), NULL);
2930 FOR_EACH_EDGE (e, ei, bb->succs)
2931 bsi_commit_one_edge_insert (e, NULL);
2935 /* Commit insertions pending at edge E. If a new block is created, set NEW_BB
2936 to this block, otherwise set it to NULL. */
2939 bsi_commit_one_edge_insert (edge e, basic_block *new_bb)
2943 if (PENDING_STMT (e))
2945 block_stmt_iterator bsi;
2946 tree stmt = PENDING_STMT (e);
2948 PENDING_STMT (e) = NULL_TREE;
2950 if (tree_find_edge_insert_loc (e, &bsi, new_bb))
2951 bsi_insert_after (&bsi, stmt, BSI_NEW_STMT);
2953 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
2958 /* Add STMT to the pending list of edge E. No actual insertion is
2959 made until a call to bsi_commit_edge_inserts () is made. */
2962 bsi_insert_on_edge (edge e, tree stmt)
2964 append_to_statement_list (stmt, &PENDING_STMT (e));
2967 /* Similar to bsi_insert_on_edge+bsi_commit_edge_inserts. If a new
2968 block has to be created, it is returned. */
2971 bsi_insert_on_edge_immediate (edge e, tree stmt)
2973 block_stmt_iterator bsi;
2974 basic_block new_bb = NULL;
2976 gcc_assert (!PENDING_STMT (e));
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 /*---------------------------------------------------------------------------
2987 Tree specific functions for CFG manipulation
2988 ---------------------------------------------------------------------------*/
2990 /* Reinstall those PHI arguments queued in OLD_EDGE to NEW_EDGE. */
2993 reinstall_phi_args (edge new_edge, edge old_edge)
2997 if (!PENDING_STMT (old_edge))
3000 for (var = PENDING_STMT (old_edge), phi = phi_nodes (new_edge->dest);
3002 var = TREE_CHAIN (var), phi = PHI_CHAIN (phi))
3004 tree result = TREE_PURPOSE (var);
3005 tree arg = TREE_VALUE (var);
3007 gcc_assert (result == PHI_RESULT (phi));
3009 add_phi_arg (phi, arg, new_edge);
3012 PENDING_STMT (old_edge) = NULL;
3015 /* Split a (typically critical) edge EDGE_IN. Return the new block.
3016 Abort on abnormal edges. */
3019 tree_split_edge (edge edge_in)
3021 basic_block new_bb, after_bb, dest, src;
3024 /* Abnormal edges cannot be split. */
3025 gcc_assert (!(edge_in->flags & EDGE_ABNORMAL));
3028 dest = edge_in->dest;
3030 /* Place the new block in the block list. Try to keep the new block
3031 near its "logical" location. This is of most help to humans looking
3032 at debugging dumps. */
3033 if (dest->prev_bb && find_edge (dest->prev_bb, dest))
3034 after_bb = edge_in->src;
3036 after_bb = dest->prev_bb;
3038 new_bb = create_empty_bb (after_bb);
3039 new_bb->frequency = EDGE_FREQUENCY (edge_in);
3040 new_bb->count = edge_in->count;
3041 new_edge = make_edge (new_bb, dest, EDGE_FALLTHRU);
3042 new_edge->probability = REG_BR_PROB_BASE;
3043 new_edge->count = edge_in->count;
3045 e = redirect_edge_and_branch (edge_in, new_bb);
3047 reinstall_phi_args (new_edge, e);
3053 /* Return true when BB has label LABEL in it. */
3056 has_label_p (basic_block bb, tree label)
3058 block_stmt_iterator bsi;
3060 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3062 tree stmt = bsi_stmt (bsi);
3064 if (TREE_CODE (stmt) != LABEL_EXPR)
3066 if (LABEL_EXPR_LABEL (stmt) == label)
3073 /* Callback for walk_tree, check that all elements with address taken are
3074 properly noticed as such. The DATA is an int* that is 1 if TP was seen
3075 inside a PHI node. */
3078 verify_expr (tree *tp, int *walk_subtrees, void *data ATTRIBUTE_UNUSED)
3081 bool in_phi = (data != NULL);
3086 /* Check operand N for being valid GIMPLE and give error MSG if not.
3087 We check for constants explicitly since they are not considered
3088 gimple invariants if they overflowed. */
3089 #define CHECK_OP(N, MSG) \
3090 do { if (!CONSTANT_CLASS_P (TREE_OPERAND (t, N)) \
3091 && !is_gimple_val (TREE_OPERAND (t, N))) \
3092 { error (MSG); return TREE_OPERAND (t, N); }} while (0)
3094 switch (TREE_CODE (t))
3097 if (SSA_NAME_IN_FREE_LIST (t))
3099 error ("SSA name in freelist but still referenced");
3105 x = fold (ASSERT_EXPR_COND (t));
3106 if (x == boolean_false_node)
3108 error ("ASSERT_EXPR with an always-false condition");
3114 x = TREE_OPERAND (t, 0);
3115 if (TREE_CODE (x) == BIT_FIELD_REF
3116 && is_gimple_reg (TREE_OPERAND (x, 0)))
3118 error ("GIMPLE register modified with BIT_FIELD_REF");
3127 bool old_side_effects;
3130 bool new_side_effects;
3132 /* ??? tree-ssa-alias.c may have overlooked dead PHI nodes, missing
3133 dead PHIs that take the address of something. But if the PHI
3134 result is dead, the fact that it takes the address of anything
3135 is irrelevant. Because we can not tell from here if a PHI result
3136 is dead, we just skip this check for PHIs altogether. This means
3137 we may be missing "valid" checks, but what can you do?
3138 This was PR19217. */
3142 old_invariant = TREE_INVARIANT (t);
3143 old_constant = TREE_CONSTANT (t);
3144 old_side_effects = TREE_SIDE_EFFECTS (t);
3146 recompute_tree_invarant_for_addr_expr (t);
3147 new_invariant = TREE_INVARIANT (t);
3148 new_side_effects = TREE_SIDE_EFFECTS (t);
3149 new_constant = TREE_CONSTANT (t);
3151 if (old_invariant != new_invariant)
3153 error ("invariant not recomputed when ADDR_EXPR changed");
3157 if (old_constant != new_constant)
3159 error ("constant not recomputed when ADDR_EXPR changed");
3162 if (old_side_effects != new_side_effects)
3164 error ("side effects not recomputed when ADDR_EXPR changed");
3168 /* Skip any references (they will be checked when we recurse down the
3169 tree) and ensure that any variable used as a prefix is marked
3171 for (x = TREE_OPERAND (t, 0);
3172 handled_component_p (x);
3173 x = TREE_OPERAND (x, 0))
3176 if (TREE_CODE (x) != VAR_DECL && TREE_CODE (x) != PARM_DECL)
3178 if (!TREE_ADDRESSABLE (x))
3180 error ("address taken, but ADDRESSABLE bit not set");
3187 x = COND_EXPR_COND (t);
3188 if (TREE_CODE (TREE_TYPE (x)) != BOOLEAN_TYPE)
3190 error ("non-boolean used in condition");
3193 if (!is_gimple_condexpr (x))
3195 error ("invalid conditional operand");
3202 case FIX_TRUNC_EXPR:
3204 case FIX_FLOOR_EXPR:
3205 case FIX_ROUND_EXPR:
3210 case NON_LVALUE_EXPR:
3211 case TRUTH_NOT_EXPR:
3212 CHECK_OP (0, "invalid operand to unary operator");
3219 case ARRAY_RANGE_REF:
3221 case VIEW_CONVERT_EXPR:
3222 /* We have a nest of references. Verify that each of the operands
3223 that determine where to reference is either a constant or a variable,
3224 verify that the base is valid, and then show we've already checked
3226 while (handled_component_p (t))
3228 if (TREE_CODE (t) == COMPONENT_REF && TREE_OPERAND (t, 2))
3229 CHECK_OP (2, "invalid COMPONENT_REF offset operator");
3230 else if (TREE_CODE (t) == ARRAY_REF
3231 || TREE_CODE (t) == ARRAY_RANGE_REF)
3233 CHECK_OP (1, "invalid array index");
3234 if (TREE_OPERAND (t, 2))
3235 CHECK_OP (2, "invalid array lower bound");
3236 if (TREE_OPERAND (t, 3))
3237 CHECK_OP (3, "invalid array stride");
3239 else if (TREE_CODE (t) == BIT_FIELD_REF)
3241 CHECK_OP (1, "invalid operand to BIT_FIELD_REF");
3242 CHECK_OP (2, "invalid operand to BIT_FIELD_REF");
3245 t = TREE_OPERAND (t, 0);
3248 if (!CONSTANT_CLASS_P (t) && !is_gimple_lvalue (t))
3250 error ("invalid reference prefix");
3262 case UNORDERED_EXPR:
3273 case TRUNC_DIV_EXPR:
3275 case FLOOR_DIV_EXPR:
3276 case ROUND_DIV_EXPR:
3277 case TRUNC_MOD_EXPR:
3279 case FLOOR_MOD_EXPR:
3280 case ROUND_MOD_EXPR:
3282 case EXACT_DIV_EXPR:
3292 CHECK_OP (0, "invalid operand to binary operator");
3293 CHECK_OP (1, "invalid operand to binary operator");
3305 /* Verify STMT, return true if STMT is not in GIMPLE form.
3306 TODO: Implement type checking. */
3309 verify_stmt (tree stmt, bool last_in_block)
3313 if (!is_gimple_stmt (stmt))
3315 error ("is not a valid GIMPLE statement");
3319 addr = walk_tree (&stmt, verify_expr, NULL, NULL);
3322 debug_generic_stmt (addr);
3326 /* If the statement is marked as part of an EH region, then it is
3327 expected that the statement could throw. Verify that when we
3328 have optimizations that simplify statements such that we prove
3329 that they cannot throw, that we update other data structures
3331 if (lookup_stmt_eh_region (stmt) >= 0)
3333 if (!tree_could_throw_p (stmt))
3335 error ("statement marked for throw, but doesn%'t");
3338 if (!last_in_block && tree_can_throw_internal (stmt))
3340 error ("statement marked for throw in middle of block");
3348 debug_generic_stmt (stmt);
3353 /* Return true when the T can be shared. */
3356 tree_node_can_be_shared (tree t)
3358 if (IS_TYPE_OR_DECL_P (t)
3359 /* We check for constants explicitly since they are not considered
3360 gimple invariants if they overflowed. */
3361 || CONSTANT_CLASS_P (t)
3362 || is_gimple_min_invariant (t)
3363 || TREE_CODE (t) == SSA_NAME
3364 || t == error_mark_node)
3367 if (TREE_CODE (t) == CASE_LABEL_EXPR)
3370 while (((TREE_CODE (t) == ARRAY_REF || TREE_CODE (t) == ARRAY_RANGE_REF)
3371 /* We check for constants explicitly since they are not considered
3372 gimple invariants if they overflowed. */
3373 && (CONSTANT_CLASS_P (TREE_OPERAND (t, 1))
3374 || is_gimple_min_invariant (TREE_OPERAND (t, 1))))
3375 || (TREE_CODE (t) == COMPONENT_REF
3376 || TREE_CODE (t) == REALPART_EXPR
3377 || TREE_CODE (t) == IMAGPART_EXPR))
3378 t = TREE_OPERAND (t, 0);
3387 /* Called via walk_trees. Verify tree sharing. */
3390 verify_node_sharing (tree * tp, int *walk_subtrees, void *data)
3392 htab_t htab = (htab_t) data;
3395 if (tree_node_can_be_shared (*tp))
3397 *walk_subtrees = false;
3401 slot = htab_find_slot (htab, *tp, INSERT);
3410 /* Verify the GIMPLE statement chain. */
3416 block_stmt_iterator bsi;
3421 timevar_push (TV_TREE_STMT_VERIFY);
3422 htab = htab_create (37, htab_hash_pointer, htab_eq_pointer, NULL);
3429 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
3431 int phi_num_args = PHI_NUM_ARGS (phi);
3433 if (bb_for_stmt (phi) != bb)
3435 error ("bb_for_stmt (phi) is set to a wrong basic block");
3439 for (i = 0; i < phi_num_args; i++)
3441 tree t = PHI_ARG_DEF (phi, i);
3444 /* Addressable variables do have SSA_NAMEs but they
3445 are not considered gimple values. */
3446 if (TREE_CODE (t) != SSA_NAME
3447 && TREE_CODE (t) != FUNCTION_DECL
3448 && !is_gimple_val (t))
3450 error ("PHI def is not a GIMPLE value");
3451 debug_generic_stmt (phi);
3452 debug_generic_stmt (t);
3456 addr = walk_tree (&t, verify_expr, (void *) 1, NULL);
3459 debug_generic_stmt (addr);
3463 addr = walk_tree (&t, verify_node_sharing, htab, NULL);
3466 error ("incorrect sharing of tree nodes");
3467 debug_generic_stmt (phi);
3468 debug_generic_stmt (addr);
3474 for (bsi = bsi_start (bb); !bsi_end_p (bsi); )
3476 tree stmt = bsi_stmt (bsi);
3478 if (bb_for_stmt (stmt) != bb)
3480 error ("bb_for_stmt (stmt) is set to a wrong basic block");
3485 err |= verify_stmt (stmt, bsi_end_p (bsi));
3486 addr = walk_tree (&stmt, verify_node_sharing, htab, NULL);
3489 error ("incorrect sharing of tree nodes");
3490 debug_generic_stmt (stmt);
3491 debug_generic_stmt (addr);
3498 internal_error ("verify_stmts failed");
3501 timevar_pop (TV_TREE_STMT_VERIFY);
3505 /* Verifies that the flow information is OK. */
3508 tree_verify_flow_info (void)
3512 block_stmt_iterator bsi;
3517 if (ENTRY_BLOCK_PTR->stmt_list)
3519 error ("ENTRY_BLOCK has a statement list associated with it");
3523 if (EXIT_BLOCK_PTR->stmt_list)
3525 error ("EXIT_BLOCK has a statement list associated with it");
3529 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
3530 if (e->flags & EDGE_FALLTHRU)
3532 error ("fallthru to exit from bb %d", e->src->index);
3538 bool found_ctrl_stmt = false;
3542 /* Skip labels on the start of basic block. */
3543 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3545 tree prev_stmt = stmt;
3547 stmt = bsi_stmt (bsi);
3549 if (TREE_CODE (stmt) != LABEL_EXPR)
3552 if (prev_stmt && DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)))
3554 error ("nonlocal label %s is not first "
3555 "in a sequence of labels in bb %d",
3556 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt))),
3561 if (label_to_block (LABEL_EXPR_LABEL (stmt)) != bb)
3563 error ("label %s to block does not match in bb %d",
3564 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt))),
3569 if (decl_function_context (LABEL_EXPR_LABEL (stmt))
3570 != current_function_decl)
3572 error ("label %s has incorrect context in bb %d",
3573 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt))),
3579 /* Verify that body of basic block BB is free of control flow. */
3580 for (; !bsi_end_p (bsi); bsi_next (&bsi))
3582 tree stmt = bsi_stmt (bsi);
3584 if (found_ctrl_stmt)
3586 error ("control flow in the middle of basic block %d",
3591 if (stmt_ends_bb_p (stmt))
3592 found_ctrl_stmt = true;
3594 if (TREE_CODE (stmt) == LABEL_EXPR)
3596 error ("label %s in the middle of basic block %d",
3597 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt))),
3602 bsi = bsi_last (bb);
3603 if (bsi_end_p (bsi))
3606 stmt = bsi_stmt (bsi);
3608 err |= verify_eh_edges (stmt);
3610 if (is_ctrl_stmt (stmt))
3612 FOR_EACH_EDGE (e, ei, bb->succs)
3613 if (e->flags & EDGE_FALLTHRU)
3615 error ("fallthru edge after a control statement in bb %d",
3621 switch (TREE_CODE (stmt))
3627 if (TREE_CODE (COND_EXPR_THEN (stmt)) != GOTO_EXPR
3628 || TREE_CODE (COND_EXPR_ELSE (stmt)) != GOTO_EXPR)
3630 error ("structured COND_EXPR at the end of bb %d", bb->index);
3634 extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
3636 if (!true_edge || !false_edge
3637 || !(true_edge->flags & EDGE_TRUE_VALUE)
3638 || !(false_edge->flags & EDGE_FALSE_VALUE)
3639 || (true_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL))
3640 || (false_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL))
3641 || EDGE_COUNT (bb->succs) >= 3)
3643 error ("wrong outgoing edge flags at end of bb %d",
3648 if (!has_label_p (true_edge->dest,
3649 GOTO_DESTINATION (COND_EXPR_THEN (stmt))))
3651 error ("%<then%> label does not match edge at end of bb %d",
3656 if (!has_label_p (false_edge->dest,
3657 GOTO_DESTINATION (COND_EXPR_ELSE (stmt))))
3659 error ("%<else%> label does not match edge at end of bb %d",
3667 if (simple_goto_p (stmt))
3669 error ("explicit goto at end of bb %d", bb->index);
3674 /* FIXME. We should double check that the labels in the
3675 destination blocks have their address taken. */
3676 FOR_EACH_EDGE (e, ei, bb->succs)
3677 if ((e->flags & (EDGE_FALLTHRU | EDGE_TRUE_VALUE
3678 | EDGE_FALSE_VALUE))
3679 || !(e->flags & EDGE_ABNORMAL))
3681 error ("wrong outgoing edge flags at end of bb %d",
3689 if (!single_succ_p (bb)
3690 || (single_succ_edge (bb)->flags
3691 & (EDGE_FALLTHRU | EDGE_ABNORMAL
3692 | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
3694 error ("wrong outgoing edge flags at end of bb %d", bb->index);
3697 if (single_succ (bb) != EXIT_BLOCK_PTR)
3699 error ("return edge does not point to exit in bb %d",
3712 vec = SWITCH_LABELS (stmt);
3713 n = TREE_VEC_LENGTH (vec);
3715 /* Mark all the destination basic blocks. */
3716 for (i = 0; i < n; ++i)
3718 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
3719 basic_block label_bb = label_to_block (lab);
3721 gcc_assert (!label_bb->aux || label_bb->aux == (void *)1);
3722 label_bb->aux = (void *)1;
3725 /* Verify that the case labels are sorted. */
3726 prev = TREE_VEC_ELT (vec, 0);
3727 for (i = 1; i < n - 1; ++i)
3729 tree c = TREE_VEC_ELT (vec, i);
3732 error ("found default case not at end of case vector");
3736 if (! tree_int_cst_lt (CASE_LOW (prev), CASE_LOW (c)))
3738 error ("case labels not sorted:");
3739 print_generic_expr (stderr, prev, 0);
3740 fprintf (stderr," is greater than ");
3741 print_generic_expr (stderr, c, 0);
3742 fprintf (stderr," but comes before it.\n");
3747 if (CASE_LOW (TREE_VEC_ELT (vec, n - 1)))
3749 error ("no default case found at end of case vector");
3753 FOR_EACH_EDGE (e, ei, bb->succs)
3757 error ("extra outgoing edge %d->%d",
3758 bb->index, e->dest->index);
3761 e->dest->aux = (void *)2;
3762 if ((e->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL
3763 | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
3765 error ("wrong outgoing edge flags at end of bb %d",
3771 /* Check that we have all of them. */
3772 for (i = 0; i < n; ++i)
3774 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
3775 basic_block label_bb = label_to_block (lab);
3777 if (label_bb->aux != (void *)2)
3779 error ("missing edge %i->%i",
3780 bb->index, label_bb->index);
3785 FOR_EACH_EDGE (e, ei, bb->succs)
3786 e->dest->aux = (void *)0;
3793 if (dom_computed[CDI_DOMINATORS] >= DOM_NO_FAST_QUERY)
3794 verify_dominators (CDI_DOMINATORS);
3800 /* Updates phi nodes after creating a forwarder block joined
3801 by edge FALLTHRU. */
3804 tree_make_forwarder_block (edge fallthru)
3808 basic_block dummy, bb;
3809 tree phi, new_phi, var;
3811 dummy = fallthru->src;
3812 bb = fallthru->dest;
3814 if (single_pred_p (bb))
3817 /* If we redirected a branch we must create new phi nodes at the
3819 for (phi = phi_nodes (dummy); phi; phi = PHI_CHAIN (phi))
3821 var = PHI_RESULT (phi);
3822 new_phi = create_phi_node (var, bb);
3823 SSA_NAME_DEF_STMT (var) = new_phi;
3824 SET_PHI_RESULT (phi, make_ssa_name (SSA_NAME_VAR (var), phi));
3825 add_phi_arg (new_phi, PHI_RESULT (phi), fallthru);
3828 /* Ensure that the PHI node chain is in the same order. */
3829 set_phi_nodes (bb, phi_reverse (phi_nodes (bb)));
3831 /* Add the arguments we have stored on edges. */
3832 FOR_EACH_EDGE (e, ei, bb->preds)
3837 flush_pending_stmts (e);
3842 /* Return a non-special label in the head of basic block BLOCK.
3843 Create one if it doesn't exist. */
3846 tree_block_label (basic_block bb)
3848 block_stmt_iterator i, s = bsi_start (bb);
3852 for (i = s; !bsi_end_p (i); first = false, bsi_next (&i))
3854 stmt = bsi_stmt (i);
3855 if (TREE_CODE (stmt) != LABEL_EXPR)
3857 label = LABEL_EXPR_LABEL (stmt);
3858 if (!DECL_NONLOCAL (label))
3861 bsi_move_before (&i, &s);
3866 label = create_artificial_label ();
3867 stmt = build1 (LABEL_EXPR, void_type_node, label);
3868 bsi_insert_before (&s, stmt, BSI_NEW_STMT);
3873 /* Attempt to perform edge redirection by replacing a possibly complex
3874 jump instruction by a goto or by removing the jump completely.
3875 This can apply only if all edges now point to the same block. The
3876 parameters and return values are equivalent to
3877 redirect_edge_and_branch. */
3880 tree_try_redirect_by_replacing_jump (edge e, basic_block target)
3882 basic_block src = e->src;
3883 block_stmt_iterator b;
3886 /* We can replace or remove a complex jump only when we have exactly
3888 if (EDGE_COUNT (src->succs) != 2
3889 /* Verify that all targets will be TARGET. Specifically, the
3890 edge that is not E must also go to TARGET. */
3891 || EDGE_SUCC (src, EDGE_SUCC (src, 0) == e)->dest != target)
3897 stmt = bsi_stmt (b);
3899 if (TREE_CODE (stmt) == COND_EXPR
3900 || TREE_CODE (stmt) == SWITCH_EXPR)
3903 e = ssa_redirect_edge (e, target);
3904 e->flags = EDGE_FALLTHRU;
3912 /* Redirect E to DEST. Return NULL on failure. Otherwise, return the
3913 edge representing the redirected branch. */
3916 tree_redirect_edge_and_branch (edge e, basic_block dest)
3918 basic_block bb = e->src;
3919 block_stmt_iterator bsi;
3923 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
3926 if (e->src != ENTRY_BLOCK_PTR
3927 && (ret = tree_try_redirect_by_replacing_jump (e, dest)))
3930 if (e->dest == dest)
3933 label = tree_block_label (dest);
3935 bsi = bsi_last (bb);
3936 stmt = bsi_end_p (bsi) ? NULL : bsi_stmt (bsi);
3938 switch (stmt ? TREE_CODE (stmt) : ERROR_MARK)
3941 stmt = (e->flags & EDGE_TRUE_VALUE
3942 ? COND_EXPR_THEN (stmt)
3943 : COND_EXPR_ELSE (stmt));
3944 GOTO_DESTINATION (stmt) = label;
3948 /* No non-abnormal edges should lead from a non-simple goto, and
3949 simple ones should be represented implicitly. */
3954 tree cases = get_cases_for_edge (e, stmt);
3956 /* If we have a list of cases associated with E, then use it
3957 as it's a lot faster than walking the entire case vector. */
3960 edge e2 = find_edge (e->src, dest);
3967 CASE_LABEL (cases) = label;
3968 cases = TREE_CHAIN (cases);
3971 /* If there was already an edge in the CFG, then we need
3972 to move all the cases associated with E to E2. */
3975 tree cases2 = get_cases_for_edge (e2, stmt);
3977 TREE_CHAIN (last) = TREE_CHAIN (cases2);
3978 TREE_CHAIN (cases2) = first;
3983 tree vec = SWITCH_LABELS (stmt);
3984 size_t i, n = TREE_VEC_LENGTH (vec);
3986 for (i = 0; i < n; i++)
3988 tree elt = TREE_VEC_ELT (vec, i);
3990 if (label_to_block (CASE_LABEL (elt)) == e->dest)
3991 CASE_LABEL (elt) = label;
4000 e->flags |= EDGE_FALLTHRU;
4004 /* Otherwise it must be a fallthru edge, and we don't need to
4005 do anything besides redirecting it. */
4006 gcc_assert (e->flags & EDGE_FALLTHRU);
4010 /* Update/insert PHI nodes as necessary. */
4012 /* Now update the edges in the CFG. */
4013 e = ssa_redirect_edge (e, dest);
4019 /* Simple wrapper, as we can always redirect fallthru edges. */
4022 tree_redirect_edge_and_branch_force (edge e, basic_block dest)
4024 e = tree_redirect_edge_and_branch (e, dest);
4031 /* Splits basic block BB after statement STMT (but at least after the
4032 labels). If STMT is NULL, BB is split just after the labels. */
4035 tree_split_block (basic_block bb, void *stmt)
4037 block_stmt_iterator bsi, bsi_tgt;
4043 new_bb = create_empty_bb (bb);
4045 /* Redirect the outgoing edges. */
4046 new_bb->succs = bb->succs;
4048 FOR_EACH_EDGE (e, ei, new_bb->succs)
4051 if (stmt && TREE_CODE ((tree) stmt) == LABEL_EXPR)
4054 /* Move everything from BSI to the new basic block. */
4055 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4057 act = bsi_stmt (bsi);
4058 if (TREE_CODE (act) == LABEL_EXPR)
4071 bsi_tgt = bsi_start (new_bb);
4072 while (!bsi_end_p (bsi))
4074 act = bsi_stmt (bsi);
4076 bsi_insert_after (&bsi_tgt, act, BSI_NEW_STMT);
4083 /* Moves basic block BB after block AFTER. */
4086 tree_move_block_after (basic_block bb, basic_block after)
4088 if (bb->prev_bb == after)
4092 link_block (bb, after);
4098 /* Return true if basic_block can be duplicated. */
4101 tree_can_duplicate_bb_p (basic_block bb ATTRIBUTE_UNUSED)
4107 /* Create a duplicate of the basic block BB. NOTE: This does not
4108 preserve SSA form. */
4111 tree_duplicate_bb (basic_block bb)
4114 block_stmt_iterator bsi, bsi_tgt;
4117 new_bb = create_empty_bb (EXIT_BLOCK_PTR->prev_bb);
4119 /* Copy the PHI nodes. We ignore PHI node arguments here because
4120 the incoming edges have not been setup yet. */
4121 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
4123 tree copy = create_phi_node (PHI_RESULT (phi), new_bb);
4124 create_new_def_for (PHI_RESULT (copy), copy, PHI_RESULT_PTR (copy));
4127 /* Keep the chain of PHI nodes in the same order so that they can be
4128 updated by ssa_redirect_edge. */
4129 set_phi_nodes (new_bb, phi_reverse (phi_nodes (new_bb)));
4131 bsi_tgt = bsi_start (new_bb);
4132 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4134 def_operand_p def_p;
4135 ssa_op_iter op_iter;
4139 stmt = bsi_stmt (bsi);
4140 if (TREE_CODE (stmt) == LABEL_EXPR)
4143 /* Create a new copy of STMT and duplicate STMT's virtual
4145 copy = unshare_expr (stmt);
4146 bsi_insert_after (&bsi_tgt, copy, BSI_NEW_STMT);
4147 copy_virtual_operands (copy, stmt);
4148 region = lookup_stmt_eh_region (stmt);
4150 add_stmt_to_eh_region (copy, region);
4152 /* Create new names for all the definitions created by COPY and
4153 add replacement mappings for each new name. */
4154 FOR_EACH_SSA_DEF_OPERAND (def_p, copy, op_iter, SSA_OP_ALL_DEFS)
4155 create_new_def_for (DEF_FROM_PTR (def_p), copy, def_p);
4162 /* Basic block BB_COPY was created by code duplication. Add phi node
4163 arguments for edges going out of BB_COPY. The blocks that were
4164 duplicated have BB_DUPLICATED set. */
4167 add_phi_args_after_copy_bb (basic_block bb_copy)
4169 basic_block bb, dest;
4172 tree phi, phi_copy, phi_next, def;
4174 bb = get_bb_original (bb_copy);
4176 FOR_EACH_EDGE (e_copy, ei, bb_copy->succs)
4178 if (!phi_nodes (e_copy->dest))
4181 if (e_copy->dest->flags & BB_DUPLICATED)
4182 dest = get_bb_original (e_copy->dest);
4184 dest = e_copy->dest;
4186 e = find_edge (bb, dest);
4189 /* During loop unrolling the target of the latch edge is copied.
4190 In this case we are not looking for edge to dest, but to
4191 duplicated block whose original was dest. */
4192 FOR_EACH_EDGE (e, ei, bb->succs)
4193 if ((e->dest->flags & BB_DUPLICATED)
4194 && get_bb_original (e->dest) == dest)
4197 gcc_assert (e != NULL);
4200 for (phi = phi_nodes (e->dest), phi_copy = phi_nodes (e_copy->dest);
4202 phi = phi_next, phi_copy = PHI_CHAIN (phi_copy))
4204 phi_next = PHI_CHAIN (phi);
4205 def = PHI_ARG_DEF_FROM_EDGE (phi, e);
4206 add_phi_arg (phi_copy, def, e_copy);
4211 /* Blocks in REGION_COPY array of length N_REGION were created by
4212 duplication of basic blocks. Add phi node arguments for edges
4213 going from these blocks. */
4216 add_phi_args_after_copy (basic_block *region_copy, unsigned n_region)
4220 for (i = 0; i < n_region; i++)
4221 region_copy[i]->flags |= BB_DUPLICATED;
4223 for (i = 0; i < n_region; i++)
4224 add_phi_args_after_copy_bb (region_copy[i]);
4226 for (i = 0; i < n_region; i++)
4227 region_copy[i]->flags &= ~BB_DUPLICATED;
4230 /* Duplicates a REGION (set of N_REGION basic blocks) with just a single
4231 important exit edge EXIT. By important we mean that no SSA name defined
4232 inside region is live over the other exit edges of the region. All entry
4233 edges to the region must go to ENTRY->dest. The edge ENTRY is redirected
4234 to the duplicate of the region. SSA form, dominance and loop information
4235 is updated. The new basic blocks are stored to REGION_COPY in the same
4236 order as they had in REGION, provided that REGION_COPY is not NULL.
4237 The function returns false if it is unable to copy the region,
4241 tree_duplicate_sese_region (edge entry, edge exit,
4242 basic_block *region, unsigned n_region,
4243 basic_block *region_copy)
4246 bool free_region_copy = false, copying_header = false;
4247 struct loop *loop = entry->dest->loop_father;
4251 int total_freq, entry_freq;
4253 if (!can_copy_bbs_p (region, n_region))
4256 /* Some sanity checking. Note that we do not check for all possible
4257 missuses of the functions. I.e. if you ask to copy something weird,
4258 it will work, but the state of structures probably will not be
4260 for (i = 0; i < n_region; i++)
4262 /* We do not handle subloops, i.e. all the blocks must belong to the
4264 if (region[i]->loop_father != loop)
4267 if (region[i] != entry->dest
4268 && region[i] == loop->header)
4274 /* In case the function is used for loop header copying (which is the primary
4275 use), ensure that EXIT and its copy will be new latch and entry edges. */
4276 if (loop->header == entry->dest)
4278 copying_header = true;
4279 loop->copy = loop->outer;
4281 if (!dominated_by_p (CDI_DOMINATORS, loop->latch, exit->src))
4284 for (i = 0; i < n_region; i++)
4285 if (region[i] != exit->src
4286 && dominated_by_p (CDI_DOMINATORS, region[i], exit->src))
4292 region_copy = xmalloc (sizeof (basic_block) * n_region);
4293 free_region_copy = true;
4296 gcc_assert (!need_ssa_update_p ());
4298 /* Record blocks outside the region that are dominated by something
4300 doms = xmalloc (sizeof (basic_block) * n_basic_blocks);
4301 initialize_original_copy_tables ();
4303 n_doms = get_dominated_by_region (CDI_DOMINATORS, region, n_region, doms);
4305 total_freq = entry->dest->frequency;
4306 entry_freq = EDGE_FREQUENCY (entry);
4307 /* Fix up corner cases, to avoid division by zero or creation of negative
4309 if (total_freq == 0)
4311 else if (entry_freq > total_freq)
4312 entry_freq = total_freq;
4314 copy_bbs (region, n_region, region_copy, &exit, 1, &exit_copy, loop);
4315 scale_bbs_frequencies_int (region, n_region, total_freq - entry_freq,
4317 scale_bbs_frequencies_int (region_copy, n_region, entry_freq, total_freq);
4321 loop->header = exit->dest;
4322 loop->latch = exit->src;
4325 /* Redirect the entry and add the phi node arguments. */
4326 redirected = redirect_edge_and_branch (entry, get_bb_copy (entry->dest));
4327 gcc_assert (redirected != NULL);
4328 flush_pending_stmts (entry);
4330 /* Concerning updating of dominators: We must recount dominators
4331 for entry block and its copy. Anything that is outside of the
4332 region, but was dominated by something inside needs recounting as
4334 set_immediate_dominator (CDI_DOMINATORS, entry->dest, entry->src);
4335 doms[n_doms++] = get_bb_original (entry->dest);
4336 iterate_fix_dominators (CDI_DOMINATORS, doms, n_doms);
4339 /* Add the other PHI node arguments. */
4340 add_phi_args_after_copy (region_copy, n_region);
4342 /* Update the SSA web. */
4343 update_ssa (TODO_update_ssa);
4345 if (free_region_copy)
4348 free_original_copy_tables ();
4353 /* Dump FUNCTION_DECL FN to file FILE using FLAGS (see TDF_* in tree.h) */
4356 dump_function_to_file (tree fn, FILE *file, int flags)
4358 tree arg, vars, var;
4359 bool ignore_topmost_bind = false, any_var = false;
4363 fprintf (file, "%s (", lang_hooks.decl_printable_name (fn, 2));
4365 arg = DECL_ARGUMENTS (fn);
4368 print_generic_expr (file, arg, dump_flags);
4369 if (TREE_CHAIN (arg))
4370 fprintf (file, ", ");
4371 arg = TREE_CHAIN (arg);
4373 fprintf (file, ")\n");
4375 if (flags & TDF_DETAILS)
4376 dump_eh_tree (file, DECL_STRUCT_FUNCTION (fn));
4377 if (flags & TDF_RAW)
4379 dump_node (fn, TDF_SLIM | flags, file);
4383 /* When GIMPLE is lowered, the variables are no longer available in
4384 BIND_EXPRs, so display them separately. */
4385 if (cfun && cfun->decl == fn && cfun->unexpanded_var_list)
4387 ignore_topmost_bind = true;
4389 fprintf (file, "{\n");
4390 for (vars = cfun->unexpanded_var_list; vars; vars = TREE_CHAIN (vars))
4392 var = TREE_VALUE (vars);
4394 print_generic_decl (file, var, flags);
4395 fprintf (file, "\n");
4401 if (cfun && cfun->decl == fn && cfun->cfg && basic_block_info)
4403 /* Make a CFG based dump. */
4404 check_bb_profile (ENTRY_BLOCK_PTR, file);
4405 if (!ignore_topmost_bind)
4406 fprintf (file, "{\n");
4408 if (any_var && n_basic_blocks)
4409 fprintf (file, "\n");
4412 dump_generic_bb (file, bb, 2, flags);
4414 fprintf (file, "}\n");
4415 check_bb_profile (EXIT_BLOCK_PTR, file);
4421 /* Make a tree based dump. */
4422 chain = DECL_SAVED_TREE (fn);
4424 if (TREE_CODE (chain) == BIND_EXPR)
4426 if (ignore_topmost_bind)
4428 chain = BIND_EXPR_BODY (chain);
4436 if (!ignore_topmost_bind)
4437 fprintf (file, "{\n");
4442 fprintf (file, "\n");
4444 print_generic_stmt_indented (file, chain, flags, indent);
4445 if (ignore_topmost_bind)
4446 fprintf (file, "}\n");
4449 fprintf (file, "\n\n");
4453 /* Pretty print of the loops intermediate representation. */
4454 static void print_loop (FILE *, struct loop *, int);
4455 static void print_pred_bbs (FILE *, basic_block bb);
4456 static void print_succ_bbs (FILE *, basic_block bb);
4459 /* Print the predecessors indexes of edge E on FILE. */
4462 print_pred_bbs (FILE *file, basic_block bb)
4467 FOR_EACH_EDGE (e, ei, bb->preds)
4468 fprintf (file, "bb_%d", e->src->index);
4472 /* Print the successors indexes of edge E on FILE. */
4475 print_succ_bbs (FILE *file, basic_block bb)
4480 FOR_EACH_EDGE (e, ei, bb->succs)
4481 fprintf (file, "bb_%d", e->src->index);
4485 /* Pretty print LOOP on FILE, indented INDENT spaces. */
4488 print_loop (FILE *file, struct loop *loop, int indent)
4496 s_indent = (char *) alloca ((size_t) indent + 1);
4497 memset ((void *) s_indent, ' ', (size_t) indent);
4498 s_indent[indent] = '\0';
4500 /* Print the loop's header. */
4501 fprintf (file, "%sloop_%d\n", s_indent, loop->num);
4503 /* Print the loop's body. */
4504 fprintf (file, "%s{\n", s_indent);
4506 if (bb->loop_father == loop)
4508 /* Print the basic_block's header. */
4509 fprintf (file, "%s bb_%d (preds = {", s_indent, bb->index);
4510 print_pred_bbs (file, bb);
4511 fprintf (file, "}, succs = {");
4512 print_succ_bbs (file, bb);
4513 fprintf (file, "})\n");
4515 /* Print the basic_block's body. */
4516 fprintf (file, "%s {\n", s_indent);
4517 tree_dump_bb (bb, file, indent + 4);
4518 fprintf (file, "%s }\n", s_indent);
4521 print_loop (file, loop->inner, indent + 2);
4522 fprintf (file, "%s}\n", s_indent);
4523 print_loop (file, loop->next, indent);
4527 /* Follow a CFG edge from the entry point of the program, and on entry
4528 of a loop, pretty print the loop structure on FILE. */
4531 print_loop_ir (FILE *file)
4535 bb = BASIC_BLOCK (0);
4536 if (bb && bb->loop_father)
4537 print_loop (file, bb->loop_father, 0);
4541 /* Debugging loops structure at tree level. */
4544 debug_loop_ir (void)
4546 print_loop_ir (stderr);
4550 /* Return true if BB ends with a call, possibly followed by some
4551 instructions that must stay with the call. Return false,
4555 tree_block_ends_with_call_p (basic_block bb)
4557 block_stmt_iterator bsi = bsi_last (bb);
4558 return get_call_expr_in (bsi_stmt (bsi)) != NULL;
4562 /* Return true if BB ends with a conditional branch. Return false,
4566 tree_block_ends_with_condjump_p (basic_block bb)
4568 tree stmt = last_stmt (bb);
4569 return (stmt && TREE_CODE (stmt) == COND_EXPR);
4573 /* Return true if we need to add fake edge to exit at statement T.
4574 Helper function for tree_flow_call_edges_add. */
4577 need_fake_edge_p (tree t)
4581 /* NORETURN and LONGJMP calls already have an edge to exit.
4582 CONST and PURE calls do not need one.
4583 We don't currently check for CONST and PURE here, although
4584 it would be a good idea, because those attributes are
4585 figured out from the RTL in mark_constant_function, and
4586 the counter incrementation code from -fprofile-arcs
4587 leads to different results from -fbranch-probabilities. */
4588 call = get_call_expr_in (t);
4590 && !(call_expr_flags (call) & ECF_NORETURN))
4593 if (TREE_CODE (t) == ASM_EXPR
4594 && (ASM_VOLATILE_P (t) || ASM_INPUT_P (t)))
4601 /* Add fake edges to the function exit for any non constant and non
4602 noreturn calls, volatile inline assembly in the bitmap of blocks
4603 specified by BLOCKS or to the whole CFG if BLOCKS is zero. Return
4604 the number of blocks that were split.
4606 The goal is to expose cases in which entering a basic block does
4607 not imply that all subsequent instructions must be executed. */
4610 tree_flow_call_edges_add (sbitmap blocks)
4613 int blocks_split = 0;
4614 int last_bb = last_basic_block;
4615 bool check_last_block = false;
4617 if (n_basic_blocks == 0)
4621 check_last_block = true;
4623 check_last_block = TEST_BIT (blocks, EXIT_BLOCK_PTR->prev_bb->index);
4625 /* In the last basic block, before epilogue generation, there will be
4626 a fallthru edge to EXIT. Special care is required if the last insn
4627 of the last basic block is a call because make_edge folds duplicate
4628 edges, which would result in the fallthru edge also being marked
4629 fake, which would result in the fallthru edge being removed by
4630 remove_fake_edges, which would result in an invalid CFG.
4632 Moreover, we can't elide the outgoing fake edge, since the block
4633 profiler needs to take this into account in order to solve the minimal
4634 spanning tree in the case that the call doesn't return.
4636 Handle this by adding a dummy instruction in a new last basic block. */
4637 if (check_last_block)
4639 basic_block bb = EXIT_BLOCK_PTR->prev_bb;
4640 block_stmt_iterator bsi = bsi_last (bb);
4642 if (!bsi_end_p (bsi))
4645 if (need_fake_edge_p (t))
4649 e = find_edge (bb, EXIT_BLOCK_PTR);
4652 bsi_insert_on_edge (e, build_empty_stmt ());
4653 bsi_commit_edge_inserts ();
4658 /* Now add fake edges to the function exit for any non constant
4659 calls since there is no way that we can determine if they will
4661 for (i = 0; i < last_bb; i++)
4663 basic_block bb = BASIC_BLOCK (i);
4664 block_stmt_iterator bsi;
4665 tree stmt, last_stmt;
4670 if (blocks && !TEST_BIT (blocks, i))
4673 bsi = bsi_last (bb);
4674 if (!bsi_end_p (bsi))
4676 last_stmt = bsi_stmt (bsi);
4679 stmt = bsi_stmt (bsi);
4680 if (need_fake_edge_p (stmt))
4683 /* The handling above of the final block before the
4684 epilogue should be enough to verify that there is
4685 no edge to the exit block in CFG already.
4686 Calling make_edge in such case would cause us to
4687 mark that edge as fake and remove it later. */
4688 #ifdef ENABLE_CHECKING
4689 if (stmt == last_stmt)
4691 e = find_edge (bb, EXIT_BLOCK_PTR);
4692 gcc_assert (e == NULL);
4696 /* Note that the following may create a new basic block
4697 and renumber the existing basic blocks. */
4698 if (stmt != last_stmt)
4700 e = split_block (bb, stmt);
4704 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
4708 while (!bsi_end_p (bsi));
4713 verify_flow_info ();
4715 return blocks_split;
4719 tree_purge_dead_eh_edges (basic_block bb)
4721 bool changed = false;
4724 tree stmt = last_stmt (bb);
4726 if (stmt && tree_can_throw_internal (stmt))
4729 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
4731 if (e->flags & EDGE_EH)
4740 /* Removal of dead EH edges might change dominators of not
4741 just immediate successors. E.g. when bb1 is changed so that
4742 it no longer can throw and bb1->bb3 and bb1->bb4 are dead
4743 eh edges purged by this function in:
4755 idom(bb5) must be recomputed. For now just free the dominance
4758 free_dominance_info (CDI_DOMINATORS);
4764 tree_purge_all_dead_eh_edges (bitmap blocks)
4766 bool changed = false;
4770 EXECUTE_IF_SET_IN_BITMAP (blocks, 0, i, bi)
4772 changed |= tree_purge_dead_eh_edges (BASIC_BLOCK (i));
4778 /* This function is called whenever a new edge is created or
4782 tree_execute_on_growing_pred (edge e)
4784 basic_block bb = e->dest;
4787 reserve_phi_args_for_new_edge (bb);
4790 /* This function is called immediately before edge E is removed from
4791 the edge vector E->dest->preds. */
4794 tree_execute_on_shrinking_pred (edge e)
4796 if (phi_nodes (e->dest))
4797 remove_phi_args (e);
4800 /*---------------------------------------------------------------------------
4801 Helper functions for Loop versioning
4802 ---------------------------------------------------------------------------*/
4804 /* Adjust phi nodes for 'first' basic block. 'second' basic block is a copy
4805 of 'first'. Both of them are dominated by 'new_head' basic block. When
4806 'new_head' was created by 'second's incoming edge it received phi arguments
4807 on the edge by split_edge(). Later, additional edge 'e' was created to
4808 connect 'new_head' and 'first'. Now this routine adds phi args on this
4809 additional edge 'e' that new_head to second edge received as part of edge
4814 tree_lv_adjust_loop_header_phi (basic_block first, basic_block second,
4815 basic_block new_head, edge e)
4818 edge e2 = find_edge (new_head, second);
4820 /* Because NEW_HEAD has been created by splitting SECOND's incoming
4821 edge, we should always have an edge from NEW_HEAD to SECOND. */
4822 gcc_assert (e2 != NULL);
4824 /* Browse all 'second' basic block phi nodes and add phi args to
4825 edge 'e' for 'first' head. PHI args are always in correct order. */
4827 for (phi2 = phi_nodes (second), phi1 = phi_nodes (first);
4829 phi2 = PHI_CHAIN (phi2), phi1 = PHI_CHAIN (phi1))
4831 tree def = PHI_ARG_DEF (phi2, e2->dest_idx);
4832 add_phi_arg (phi1, def, e);
4836 /* Adds a if else statement to COND_BB with condition COND_EXPR.
4837 SECOND_HEAD is the destination of the THEN and FIRST_HEAD is
4838 the destination of the ELSE part. */
4840 tree_lv_add_condition_to_bb (basic_block first_head, basic_block second_head,
4841 basic_block cond_bb, void *cond_e)
4843 block_stmt_iterator bsi;
4844 tree goto1 = NULL_TREE;
4845 tree goto2 = NULL_TREE;
4846 tree new_cond_expr = NULL_TREE;
4847 tree cond_expr = (tree) cond_e;
4850 /* Build new conditional expr */
4851 goto1 = build1 (GOTO_EXPR, void_type_node, tree_block_label (first_head));
4852 goto2 = build1 (GOTO_EXPR, void_type_node, tree_block_label (second_head));
4853 new_cond_expr = build3 (COND_EXPR, void_type_node, cond_expr, goto1, goto2);
4855 /* Add new cond in cond_bb. */
4856 bsi = bsi_start (cond_bb);
4857 bsi_insert_after (&bsi, new_cond_expr, BSI_NEW_STMT);
4858 /* Adjust edges appropriately to connect new head with first head
4859 as well as second head. */
4860 e0 = single_succ_edge (cond_bb);
4861 e0->flags &= ~EDGE_FALLTHRU;
4862 e0->flags |= EDGE_FALSE_VALUE;
4865 struct cfg_hooks tree_cfg_hooks = {
4867 tree_verify_flow_info,
4868 tree_dump_bb, /* dump_bb */
4869 create_bb, /* create_basic_block */
4870 tree_redirect_edge_and_branch,/* redirect_edge_and_branch */
4871 tree_redirect_edge_and_branch_force,/* redirect_edge_and_branch_force */
4872 remove_bb, /* delete_basic_block */
4873 tree_split_block, /* split_block */
4874 tree_move_block_after, /* move_block_after */
4875 tree_can_merge_blocks_p, /* can_merge_blocks_p */
4876 tree_merge_blocks, /* merge_blocks */
4877 tree_predict_edge, /* predict_edge */
4878 tree_predicted_by_p, /* predicted_by_p */
4879 tree_can_duplicate_bb_p, /* can_duplicate_block_p */
4880 tree_duplicate_bb, /* duplicate_block */
4881 tree_split_edge, /* split_edge */
4882 tree_make_forwarder_block, /* make_forward_block */
4883 NULL, /* tidy_fallthru_edge */
4884 tree_block_ends_with_call_p, /* block_ends_with_call_p */
4885 tree_block_ends_with_condjump_p, /* block_ends_with_condjump_p */
4886 tree_flow_call_edges_add, /* flow_call_edges_add */
4887 tree_execute_on_growing_pred, /* execute_on_growing_pred */
4888 tree_execute_on_shrinking_pred, /* execute_on_shrinking_pred */
4889 tree_duplicate_loop_to_header_edge, /* duplicate loop for trees */
4890 tree_lv_add_condition_to_bb, /* lv_add_condition_to_bb */
4891 tree_lv_adjust_loop_header_phi, /* lv_adjust_loop_header_phi*/
4892 extract_true_false_edges_from_block, /* extract_cond_bb_edges */
4893 flush_pending_stmts /* flush_pending_stmts */
4897 /* Split all critical edges. */
4900 split_critical_edges (void)
4906 /* split_edge can redirect edges out of SWITCH_EXPRs, which can get
4907 expensive. So we want to enable recording of edge to CASE_LABEL_EXPR
4908 mappings around the calls to split_edge. */
4909 start_recording_case_labels ();
4912 FOR_EACH_EDGE (e, ei, bb->succs)
4913 if (EDGE_CRITICAL_P (e) && !(e->flags & EDGE_ABNORMAL))
4918 end_recording_case_labels ();
4921 struct tree_opt_pass pass_split_crit_edges =
4923 "crited", /* name */
4925 split_critical_edges, /* execute */
4928 0, /* static_pass_number */
4929 TV_TREE_SPLIT_EDGES, /* tv_id */
4930 PROP_cfg, /* properties required */
4931 PROP_no_crit_edges, /* properties_provided */
4932 0, /* properties_destroyed */
4933 0, /* todo_flags_start */
4934 TODO_dump_func, /* todo_flags_finish */
4939 /* Return EXP if it is a valid GIMPLE rvalue, else gimplify it into
4940 a temporary, make sure and register it to be renamed if necessary,
4941 and finally return the temporary. Put the statements to compute
4942 EXP before the current statement in BSI. */
4945 gimplify_val (block_stmt_iterator *bsi, tree type, tree exp)
4947 tree t, new_stmt, orig_stmt;
4949 if (is_gimple_val (exp))
4952 t = make_rename_temp (type, NULL);
4953 new_stmt = build (MODIFY_EXPR, type, t, exp);
4955 orig_stmt = bsi_stmt (*bsi);
4956 SET_EXPR_LOCUS (new_stmt, EXPR_LOCUS (orig_stmt));
4957 TREE_BLOCK (new_stmt) = TREE_BLOCK (orig_stmt);
4959 bsi_insert_before (bsi, new_stmt, BSI_SAME_STMT);
4964 /* Build a ternary operation and gimplify it. Emit code before BSI.
4965 Return the gimple_val holding the result. */
4968 gimplify_build3 (block_stmt_iterator *bsi, enum tree_code code,
4969 tree type, tree a, tree b, tree c)
4973 ret = fold_build3 (code, type, a, b, c);
4976 return gimplify_val (bsi, type, ret);
4979 /* Build a binary operation and gimplify it. Emit code before BSI.
4980 Return the gimple_val holding the result. */
4983 gimplify_build2 (block_stmt_iterator *bsi, enum tree_code code,
4984 tree type, tree a, tree b)
4988 ret = fold_build2 (code, type, a, b);
4991 return gimplify_val (bsi, type, ret);
4994 /* Build a unary operation and gimplify it. Emit code before BSI.
4995 Return the gimple_val holding the result. */
4998 gimplify_build1 (block_stmt_iterator *bsi, enum tree_code code, tree type,
5003 ret = fold_build1 (code, type, a);
5006 return gimplify_val (bsi, type, ret);
5011 /* Emit return warnings. */
5014 execute_warn_function_return (void)
5016 #ifdef USE_MAPPED_LOCATION
5017 source_location location;
5025 /* If we have a path to EXIT, then we do return. */
5026 if (TREE_THIS_VOLATILE (cfun->decl)
5027 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) > 0)
5029 #ifdef USE_MAPPED_LOCATION
5030 location = UNKNOWN_LOCATION;
5034 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
5036 last = last_stmt (e->src);
5037 if (TREE_CODE (last) == RETURN_EXPR
5038 #ifdef USE_MAPPED_LOCATION
5039 && (location = EXPR_LOCATION (last)) != UNKNOWN_LOCATION)
5041 && (locus = EXPR_LOCUS (last)) != NULL)
5045 #ifdef USE_MAPPED_LOCATION
5046 if (location == UNKNOWN_LOCATION)
5047 location = cfun->function_end_locus;
5048 warning (0, "%H%<noreturn%> function does return", &location);
5051 locus = &cfun->function_end_locus;
5052 warning (0, "%H%<noreturn%> function does return", locus);
5056 /* If we see "return;" in some basic block, then we do reach the end
5057 without returning a value. */
5058 else if (warn_return_type
5059 && !TREE_NO_WARNING (cfun->decl)
5060 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) > 0
5061 && !VOID_TYPE_P (TREE_TYPE (TREE_TYPE (cfun->decl))))
5063 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
5065 tree last = last_stmt (e->src);
5066 if (TREE_CODE (last) == RETURN_EXPR
5067 && TREE_OPERAND (last, 0) == NULL)
5069 #ifdef USE_MAPPED_LOCATION
5070 location = EXPR_LOCATION (last);
5071 if (location == UNKNOWN_LOCATION)
5072 location = cfun->function_end_locus;
5073 warning (0, "%Hcontrol reaches end of non-void function", &location);
5075 locus = EXPR_LOCUS (last);
5077 locus = &cfun->function_end_locus;
5078 warning (0, "%Hcontrol reaches end of non-void function", locus);
5080 TREE_NO_WARNING (cfun->decl) = 1;
5088 /* Given a basic block B which ends with a conditional and has
5089 precisely two successors, determine which of the edges is taken if
5090 the conditional is true and which is taken if the conditional is
5091 false. Set TRUE_EDGE and FALSE_EDGE appropriately. */
5094 extract_true_false_edges_from_block (basic_block b,
5098 edge e = EDGE_SUCC (b, 0);
5100 if (e->flags & EDGE_TRUE_VALUE)
5103 *false_edge = EDGE_SUCC (b, 1);
5108 *true_edge = EDGE_SUCC (b, 1);
5112 struct tree_opt_pass pass_warn_function_return =
5116 execute_warn_function_return, /* execute */
5119 0, /* static_pass_number */
5121 PROP_cfg, /* properties_required */
5122 0, /* properties_provided */
5123 0, /* properties_destroyed */
5124 0, /* todo_flags_start */
5125 0, /* todo_flags_finish */
5129 /* Emit noreturn warnings. */
5132 execute_warn_function_noreturn (void)
5134 if (warn_missing_noreturn
5135 && !TREE_THIS_VOLATILE (cfun->decl)
5136 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) == 0
5137 && !lang_hooks.function.missing_noreturn_ok_p (cfun->decl))
5138 warning (OPT_Wmissing_noreturn, "%Jfunction might be possible candidate "
5139 "for attribute %<noreturn%>",
5143 struct tree_opt_pass pass_warn_function_noreturn =
5147 execute_warn_function_noreturn, /* execute */
5150 0, /* static_pass_number */
5152 PROP_cfg, /* properties_required */
5153 0, /* properties_provided */
5154 0, /* properties_destroyed */
5155 0, /* todo_flags_start */
5156 0, /* todo_flags_finish */