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, 59 Temple Place - Suite 330,
20 Boston, MA 02111-1307, USA. */
24 #include "coretypes.h"
29 #include "hard-reg-set.h"
30 #include "basic-block.h"
37 #include "langhooks.h"
38 #include "diagnostic.h"
39 #include "tree-flow.h"
41 #include "tree-dump.h"
42 #include "tree-pass.h"
46 #include "cfglayout.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 /* Mapping of labels to their associated blocks. This can greatly speed up
58 building of the CFG in code with lots of gotos. */
59 static GTY(()) varray_type label_to_block_map;
61 /* This hash table allows us to efficiently lookup all CASE_LABEL_EXPRs
62 which use a particular edge. The CASE_LABEL_EXPRs are chained together
63 via their TREE_CHAIN field, which we clear after we're done with the
64 hash table to prevent problems with duplication of SWITCH_EXPRs.
66 Access to this list of CASE_LABEL_EXPRs allows us to efficiently
67 update the case vector in response to edge redirections.
69 Right now this table is set up and torn down at key points in the
70 compilation process. It would be nice if we could make the table
71 more persistent. The key is getting notification of changes to
72 the CFG (particularly edge removal, creation and redirection). */
74 struct edge_to_cases_elt
76 /* The edge itself. Necessary for hashing and equality tests. */
79 /* The case labels associated with this edge. We link these up via
80 their TREE_CHAIN field, then we wipe out the TREE_CHAIN fields
81 when we destroy the hash table. This prevents problems when copying
86 static htab_t edge_to_cases;
91 long num_merged_labels;
94 static struct cfg_stats_d cfg_stats;
96 /* Nonzero if we found a computed goto while building basic blocks. */
97 static bool found_computed_goto;
99 /* Basic blocks and flowgraphs. */
100 static basic_block create_bb (void *, void *, basic_block);
101 static void create_block_annotation (basic_block);
102 static void free_blocks_annotations (void);
103 static void clear_blocks_annotations (void);
104 static void make_blocks (tree);
105 static void factor_computed_gotos (void);
108 static void make_edges (void);
109 static void make_ctrl_stmt_edges (basic_block);
110 static void make_exit_edges (basic_block);
111 static void make_cond_expr_edges (basic_block);
112 static void make_switch_expr_edges (basic_block);
113 static void make_goto_expr_edges (basic_block);
114 static edge tree_redirect_edge_and_branch (edge, basic_block);
115 static edge tree_try_redirect_by_replacing_jump (edge, basic_block);
116 static void split_critical_edges (void);
117 static bool remove_fallthru_edge (VEC(edge) *);
119 /* Various helpers. */
120 static inline bool stmt_starts_bb_p (tree, tree);
121 static int tree_verify_flow_info (void);
122 static void tree_make_forwarder_block (edge);
123 static bool tree_forwarder_block_p (basic_block, bool);
124 static void tree_cfg2vcg (FILE *);
126 /* Flowgraph optimization and cleanup. */
127 static void tree_merge_blocks (basic_block, basic_block);
128 static bool tree_can_merge_blocks_p (basic_block, basic_block);
129 static void remove_bb (basic_block);
130 static bool cleanup_control_flow (void);
131 static bool cleanup_control_expr_graph (basic_block, block_stmt_iterator);
132 static edge find_taken_edge_computed_goto (basic_block, tree);
133 static edge find_taken_edge_cond_expr (basic_block, tree);
134 static edge find_taken_edge_switch_expr (basic_block, tree);
135 static tree find_case_label_for_value (tree, tree);
136 static bool phi_alternatives_equal (basic_block, edge, edge);
137 static bool cleanup_forwarder_blocks (void);
140 /*---------------------------------------------------------------------------
142 ---------------------------------------------------------------------------*/
144 /* Entry point to the CFG builder for trees. TP points to the list of
145 statements to be added to the flowgraph. */
148 build_tree_cfg (tree *tp)
150 /* Register specific tree functions. */
151 tree_register_cfg_hooks ();
153 /* Initialize rbi_pool. */
156 /* Initialize the basic block array. */
158 profile_status = PROFILE_ABSENT;
160 last_basic_block = 0;
161 VARRAY_BB_INIT (basic_block_info, initial_cfg_capacity, "basic_block_info");
162 memset ((void *) &cfg_stats, 0, sizeof (cfg_stats));
164 /* Build a mapping of labels to their associated blocks. */
165 VARRAY_BB_INIT (label_to_block_map, initial_cfg_capacity,
166 "label to block map");
168 ENTRY_BLOCK_PTR->next_bb = EXIT_BLOCK_PTR;
169 EXIT_BLOCK_PTR->prev_bb = ENTRY_BLOCK_PTR;
171 found_computed_goto = 0;
174 /* Computed gotos are hell to deal with, especially if there are
175 lots of them with a large number of destinations. So we factor
176 them to a common computed goto location before we build the
177 edge list. After we convert back to normal form, we will un-factor
178 the computed gotos since factoring introduces an unwanted jump. */
179 if (found_computed_goto)
180 factor_computed_gotos ();
182 /* Make sure there is always at least one block, even if it's empty. */
183 if (n_basic_blocks == 0)
184 create_empty_bb (ENTRY_BLOCK_PTR);
186 create_block_annotation (ENTRY_BLOCK_PTR);
187 create_block_annotation (EXIT_BLOCK_PTR);
189 /* Adjust the size of the array. */
190 VARRAY_GROW (basic_block_info, n_basic_blocks);
192 /* To speed up statement iterator walks, we first purge dead labels. */
193 cleanup_dead_labels ();
195 /* Group case nodes to reduce the number of edges.
196 We do this after cleaning up dead labels because otherwise we miss
197 a lot of obvious case merging opportunities. */
198 group_case_labels ();
200 /* Create the edges of the flowgraph. */
203 /* Debugging dumps. */
205 /* Write the flowgraph to a VCG file. */
207 int local_dump_flags;
208 FILE *dump_file = dump_begin (TDI_vcg, &local_dump_flags);
211 tree_cfg2vcg (dump_file);
212 dump_end (TDI_vcg, dump_file);
216 /* Dump a textual representation of the flowgraph. */
218 dump_tree_cfg (dump_file, dump_flags);
222 execute_build_cfg (void)
224 build_tree_cfg (&DECL_SAVED_TREE (current_function_decl));
227 struct tree_opt_pass pass_build_cfg =
231 execute_build_cfg, /* execute */
234 0, /* static_pass_number */
235 TV_TREE_CFG, /* tv_id */
236 PROP_gimple_leh, /* properties_required */
237 PROP_cfg, /* properties_provided */
238 0, /* properties_destroyed */
239 0, /* todo_flags_start */
240 TODO_verify_stmts, /* todo_flags_finish */
244 /* Search the CFG for any computed gotos. If found, factor them to a
245 common computed goto site. Also record the location of that site so
246 that we can un-factor the gotos after we have converted back to
250 factor_computed_gotos (void)
253 tree factored_label_decl = NULL;
255 tree factored_computed_goto_label = NULL;
256 tree factored_computed_goto = NULL;
258 /* We know there are one or more computed gotos in this function.
259 Examine the last statement in each basic block to see if the block
260 ends with a computed goto. */
264 block_stmt_iterator bsi = bsi_last (bb);
269 last = bsi_stmt (bsi);
271 /* Ignore the computed goto we create when we factor the original
273 if (last == factored_computed_goto)
276 /* If the last statement is a computed goto, factor it. */
277 if (computed_goto_p (last))
281 /* The first time we find a computed goto we need to create
282 the factored goto block and the variable each original
283 computed goto will use for their goto destination. */
284 if (! factored_computed_goto)
286 basic_block new_bb = create_empty_bb (bb);
287 block_stmt_iterator new_bsi = bsi_start (new_bb);
289 /* Create the destination of the factored goto. Each original
290 computed goto will put its desired destination into this
291 variable and jump to the label we create immediately
293 var = create_tmp_var (ptr_type_node, "gotovar");
295 /* Build a label for the new block which will contain the
296 factored computed goto. */
297 factored_label_decl = create_artificial_label ();
298 factored_computed_goto_label
299 = build1 (LABEL_EXPR, void_type_node, factored_label_decl);
300 bsi_insert_after (&new_bsi, factored_computed_goto_label,
303 /* Build our new computed goto. */
304 factored_computed_goto = build1 (GOTO_EXPR, void_type_node, var);
305 bsi_insert_after (&new_bsi, factored_computed_goto,
309 /* Copy the original computed goto's destination into VAR. */
310 assignment = build (MODIFY_EXPR, ptr_type_node,
311 var, GOTO_DESTINATION (last));
312 bsi_insert_before (&bsi, assignment, BSI_SAME_STMT);
314 /* And re-vector the computed goto to the new destination. */
315 GOTO_DESTINATION (last) = factored_label_decl;
321 /* Create annotations for a single basic block. */
324 create_block_annotation (basic_block bb)
326 /* Verify that the tree_annotations field is clear. */
327 gcc_assert (!bb->tree_annotations);
328 bb->tree_annotations = ggc_alloc_cleared (sizeof (struct bb_ann_d));
332 /* Free the annotations for all the basic blocks. */
334 static void free_blocks_annotations (void)
336 clear_blocks_annotations ();
340 /* Clear the annotations for all the basic blocks. */
343 clear_blocks_annotations (void)
347 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb)
348 bb->tree_annotations = NULL;
352 /* Build a flowgraph for the statement_list STMT_LIST. */
355 make_blocks (tree stmt_list)
357 tree_stmt_iterator i = tsi_start (stmt_list);
359 bool start_new_block = true;
360 bool first_stmt_of_list = true;
361 basic_block bb = ENTRY_BLOCK_PTR;
363 while (!tsi_end_p (i))
370 /* If the statement starts a new basic block or if we have determined
371 in a previous pass that we need to create a new block for STMT, do
373 if (start_new_block || stmt_starts_bb_p (stmt, prev_stmt))
375 if (!first_stmt_of_list)
376 stmt_list = tsi_split_statement_list_before (&i);
377 bb = create_basic_block (stmt_list, NULL, bb);
378 start_new_block = false;
381 /* Now add STMT to BB and create the subgraphs for special statement
383 set_bb_for_stmt (stmt, bb);
385 if (computed_goto_p (stmt))
386 found_computed_goto = true;
388 /* If STMT is a basic block terminator, set START_NEW_BLOCK for the
390 if (stmt_ends_bb_p (stmt))
391 start_new_block = true;
394 first_stmt_of_list = false;
399 /* Create and return a new empty basic block after bb AFTER. */
402 create_bb (void *h, void *e, basic_block after)
408 /* Create and initialize a new basic block. Since alloc_block uses
409 ggc_alloc_cleared to allocate a basic block, we do not have to
410 clear the newly allocated basic block here. */
413 bb->index = last_basic_block;
415 bb->stmt_list = h ? h : alloc_stmt_list ();
417 /* Add the new block to the linked list of blocks. */
418 link_block (bb, after);
420 /* Grow the basic block array if needed. */
421 if ((size_t) last_basic_block == VARRAY_SIZE (basic_block_info))
423 size_t new_size = last_basic_block + (last_basic_block + 3) / 4;
424 VARRAY_GROW (basic_block_info, new_size);
427 /* Add the newly created block to the array. */
428 BASIC_BLOCK (last_basic_block) = bb;
430 create_block_annotation (bb);
435 initialize_bb_rbi (bb);
440 /*---------------------------------------------------------------------------
442 ---------------------------------------------------------------------------*/
444 /* Fold COND_EXPR_COND of each COND_EXPR. */
447 fold_cond_expr_cond (void)
453 tree stmt = last_stmt (bb);
456 && TREE_CODE (stmt) == COND_EXPR)
458 tree cond = fold (COND_EXPR_COND (stmt));
459 if (integer_zerop (cond))
460 COND_EXPR_COND (stmt) = integer_zero_node;
461 else if (integer_onep (cond))
462 COND_EXPR_COND (stmt) = integer_one_node;
467 /* Join all the blocks in the flowgraph. */
474 /* Create an edge from entry to the first block with executable
476 make_edge (ENTRY_BLOCK_PTR, BASIC_BLOCK (0), EDGE_FALLTHRU);
478 /* Traverse the basic block array placing edges. */
481 tree first = first_stmt (bb);
482 tree last = last_stmt (bb);
486 /* Edges for statements that always alter flow control. */
487 if (is_ctrl_stmt (last))
488 make_ctrl_stmt_edges (bb);
490 /* Edges for statements that sometimes alter flow control. */
491 if (is_ctrl_altering_stmt (last))
492 make_exit_edges (bb);
495 /* Finally, if no edges were created above, this is a regular
496 basic block that only needs a fallthru edge. */
497 if (EDGE_COUNT (bb->succs) == 0)
498 make_edge (bb, bb->next_bb, EDGE_FALLTHRU);
501 /* We do not care about fake edges, so remove any that the CFG
502 builder inserted for completeness. */
503 remove_fake_exit_edges ();
505 /* Fold COND_EXPR_COND of each COND_EXPR. */
506 fold_cond_expr_cond ();
508 /* Clean up the graph and warn for unreachable code. */
513 /* Create edges for control statement at basic block BB. */
516 make_ctrl_stmt_edges (basic_block bb)
518 tree last = last_stmt (bb);
521 switch (TREE_CODE (last))
524 make_goto_expr_edges (bb);
528 make_edge (bb, EXIT_BLOCK_PTR, 0);
532 make_cond_expr_edges (bb);
536 make_switch_expr_edges (bb);
540 make_eh_edges (last);
541 /* Yet another NORETURN hack. */
542 if (EDGE_COUNT (bb->succs) == 0)
543 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
552 /* Create exit edges for statements in block BB that alter the flow of
553 control. Statements that alter the control flow are 'goto', 'return'
554 and calls to non-returning functions. */
557 make_exit_edges (basic_block bb)
559 tree last = last_stmt (bb), op;
562 switch (TREE_CODE (last))
565 /* If this function receives a nonlocal goto, then we need to
566 make edges from this call site to all the nonlocal goto
568 if (TREE_SIDE_EFFECTS (last)
569 && current_function_has_nonlocal_label)
570 make_goto_expr_edges (bb);
572 /* If this statement has reachable exception handlers, then
573 create abnormal edges to them. */
574 make_eh_edges (last);
576 /* Some calls are known not to return. For such calls we create
579 We really need to revamp how we build edges so that it's not
580 such a bloody pain to avoid creating edges for this case since
581 all we do is remove these edges when we're done building the
583 if (call_expr_flags (last) & ECF_NORETURN)
585 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
589 /* Don't forget the fall-thru edge. */
590 make_edge (bb, bb->next_bb, EDGE_FALLTHRU);
594 /* A MODIFY_EXPR may have a CALL_EXPR on its RHS and the CALL_EXPR
595 may have an abnormal edge. Search the RHS for this case and
596 create any required edges. */
597 op = get_call_expr_in (last);
598 if (op && TREE_SIDE_EFFECTS (op)
599 && current_function_has_nonlocal_label)
600 make_goto_expr_edges (bb);
602 make_eh_edges (last);
603 make_edge (bb, bb->next_bb, EDGE_FALLTHRU);
612 /* Create the edges for a COND_EXPR starting at block BB.
613 At this point, both clauses must contain only simple gotos. */
616 make_cond_expr_edges (basic_block bb)
618 tree entry = last_stmt (bb);
619 basic_block then_bb, else_bb;
620 tree then_label, else_label;
623 gcc_assert (TREE_CODE (entry) == COND_EXPR);
625 /* Entry basic blocks for each component. */
626 then_label = GOTO_DESTINATION (COND_EXPR_THEN (entry));
627 else_label = GOTO_DESTINATION (COND_EXPR_ELSE (entry));
628 then_bb = label_to_block (then_label);
629 else_bb = label_to_block (else_label);
631 make_edge (bb, then_bb, EDGE_TRUE_VALUE);
632 make_edge (bb, else_bb, EDGE_FALSE_VALUE);
635 /* Hashing routine for EDGE_TO_CASES. */
638 edge_to_cases_hash (const void *p)
640 edge e = ((struct edge_to_cases_elt *)p)->e;
642 /* Hash on the edge itself (which is a pointer). */
643 return htab_hash_pointer (e);
646 /* Equality routine for EDGE_TO_CASES, edges are unique, so testing
647 for equality is just a pointer comparison. */
650 edge_to_cases_eq (const void *p1, const void *p2)
652 edge e1 = ((struct edge_to_cases_elt *)p1)->e;
653 edge e2 = ((struct edge_to_cases_elt *)p2)->e;
658 /* Called for each element in the hash table (P) as we delete the
659 edge to cases hash table.
661 Clear all the TREE_CHAINs to prevent problems with copying of
662 SWITCH_EXPRs and structure sharing rules, then free the hash table
666 edge_to_cases_cleanup (void *p)
668 struct edge_to_cases_elt *elt = p;
671 for (t = elt->case_labels; t; t = next)
673 next = TREE_CHAIN (t);
674 TREE_CHAIN (t) = NULL;
679 /* Start recording information mapping edges to case labels. */
682 start_recording_case_labels (void)
684 gcc_assert (edge_to_cases == NULL);
686 edge_to_cases = htab_create (37,
689 edge_to_cases_cleanup);
692 /* Return nonzero if we are recording information for case labels. */
695 recording_case_labels_p (void)
697 return (edge_to_cases != NULL);
700 /* Stop recording information mapping edges to case labels and
701 remove any information we have recorded. */
703 end_recording_case_labels (void)
705 htab_delete (edge_to_cases);
706 edge_to_cases = NULL;
709 /* Record that CASE_LABEL (a CASE_LABEL_EXPR) references edge E. */
712 record_switch_edge (edge e, tree case_label)
714 struct edge_to_cases_elt *elt;
717 /* Build a hash table element so we can see if E is already
719 elt = xmalloc (sizeof (struct edge_to_cases_elt));
721 elt->case_labels = case_label;
723 slot = htab_find_slot (edge_to_cases, elt, INSERT);
727 /* E was not in the hash table. Install E into the hash table. */
732 /* E was already in the hash table. Free ELT as we do not need it
736 /* Get the entry stored in the hash table. */
737 elt = (struct edge_to_cases_elt *) *slot;
739 /* Add it to the chain of CASE_LABEL_EXPRs referencing E. */
740 TREE_CHAIN (case_label) = elt->case_labels;
741 elt->case_labels = case_label;
745 /* If we are inside a {start,end}_recording_cases block, then return
746 a chain of CASE_LABEL_EXPRs from T which reference E.
748 Otherwise return NULL. */
751 get_cases_for_edge (edge e, tree t)
753 struct edge_to_cases_elt elt, *elt_p;
758 /* If we are not recording cases, then we do not have CASE_LABEL_EXPR
759 chains available. Return NULL so the caller can detect this case. */
760 if (!recording_case_labels_p ())
765 elt.case_labels = NULL;
766 slot = htab_find_slot (edge_to_cases, &elt, NO_INSERT);
770 elt_p = (struct edge_to_cases_elt *)*slot;
771 return elt_p->case_labels;
774 /* If we did not find E in the hash table, then this must be the first
775 time we have been queried for information about E & T. Add all the
776 elements from T to the hash table then perform the query again. */
778 vec = SWITCH_LABELS (t);
779 n = TREE_VEC_LENGTH (vec);
780 for (i = 0; i < n; i++)
782 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
783 basic_block label_bb = label_to_block (lab);
784 record_switch_edge (find_edge (e->src, label_bb), TREE_VEC_ELT (vec, i));
789 /* Create the edges for a SWITCH_EXPR starting at block BB.
790 At this point, the switch body has been lowered and the
791 SWITCH_LABELS filled in, so this is in effect a multi-way branch. */
794 make_switch_expr_edges (basic_block bb)
796 tree entry = last_stmt (bb);
800 vec = SWITCH_LABELS (entry);
801 n = TREE_VEC_LENGTH (vec);
803 for (i = 0; i < n; ++i)
805 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
806 basic_block label_bb = label_to_block (lab);
807 make_edge (bb, label_bb, 0);
812 /* Return the basic block holding label DEST. */
815 label_to_block (tree dest)
817 int uid = LABEL_DECL_UID (dest);
819 /* We would die hard when faced by an undefined label. Emit a label to
820 the very first basic block. This will hopefully make even the dataflow
821 and undefined variable warnings quite right. */
822 if ((errorcount || sorrycount) && uid < 0)
824 block_stmt_iterator bsi = bsi_start (BASIC_BLOCK (0));
827 stmt = build1 (LABEL_EXPR, void_type_node, dest);
828 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
829 uid = LABEL_DECL_UID (dest);
831 return VARRAY_BB (label_to_block_map, uid);
835 /* Create edges for a goto statement at block BB. */
838 make_goto_expr_edges (basic_block bb)
841 basic_block target_bb;
843 block_stmt_iterator last = bsi_last (bb);
845 goto_t = bsi_stmt (last);
847 /* If the last statement is not a GOTO (i.e., it is a RETURN_EXPR,
848 CALL_EXPR or MODIFY_EXPR), then the edge is an abnormal edge resulting
849 from a nonlocal goto. */
850 if (TREE_CODE (goto_t) != GOTO_EXPR)
852 dest = error_mark_node;
857 dest = GOTO_DESTINATION (goto_t);
860 /* A GOTO to a local label creates normal edges. */
861 if (simple_goto_p (goto_t))
863 edge e = make_edge (bb, label_to_block (dest), EDGE_FALLTHRU);
864 #ifdef USE_MAPPED_LOCATION
865 e->goto_locus = EXPR_LOCATION (goto_t);
867 e->goto_locus = EXPR_LOCUS (goto_t);
873 /* Nothing more to do for nonlocal gotos. */
874 if (TREE_CODE (dest) == LABEL_DECL)
877 /* Computed gotos remain. */
880 /* Look for the block starting with the destination label. In the
881 case of a computed goto, make an edge to any label block we find
883 FOR_EACH_BB (target_bb)
885 block_stmt_iterator bsi;
887 for (bsi = bsi_start (target_bb); !bsi_end_p (bsi); bsi_next (&bsi))
889 tree target = bsi_stmt (bsi);
891 if (TREE_CODE (target) != LABEL_EXPR)
895 /* Computed GOTOs. Make an edge to every label block that has
896 been marked as a potential target for a computed goto. */
897 (FORCED_LABEL (LABEL_EXPR_LABEL (target)) && for_call == 0)
898 /* Nonlocal GOTO target. Make an edge to every label block
899 that has been marked as a potential target for a nonlocal
901 || (DECL_NONLOCAL (LABEL_EXPR_LABEL (target)) && for_call == 1))
903 make_edge (bb, target_bb, EDGE_ABNORMAL);
909 /* Degenerate case of computed goto with no labels. */
910 if (!for_call && EDGE_COUNT (bb->succs) == 0)
911 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
915 /*---------------------------------------------------------------------------
917 ---------------------------------------------------------------------------*/
919 /* Remove unreachable blocks and other miscellaneous clean up work. */
922 cleanup_tree_cfg (void)
926 timevar_push (TV_TREE_CLEANUP_CFG);
928 retval = cleanup_control_flow ();
929 retval |= delete_unreachable_blocks ();
931 /* cleanup_forwarder_blocks can redirect edges out of SWITCH_EXPRs,
932 which can get expensive. So we want to enable recording of edge
933 to CASE_LABEL_EXPR mappings around the call to
934 cleanup_forwarder_blocks. */
935 start_recording_case_labels ();
936 retval |= cleanup_forwarder_blocks ();
937 end_recording_case_labels ();
939 #ifdef ENABLE_CHECKING
942 gcc_assert (!cleanup_control_flow ());
943 gcc_assert (!delete_unreachable_blocks ());
944 gcc_assert (!cleanup_forwarder_blocks ());
948 /* Merging the blocks creates no new opportunities for the other
949 optimizations, so do it here. */
950 retval |= merge_seq_blocks ();
954 #ifdef ENABLE_CHECKING
957 timevar_pop (TV_TREE_CLEANUP_CFG);
962 /* Cleanup useless labels in basic blocks. This is something we wish
963 to do early because it allows us to group case labels before creating
964 the edges for the CFG, and it speeds up block statement iterators in
966 We only run this pass once, running it more than once is probably not
969 /* A map from basic block index to the leading label of that block. */
970 static tree *label_for_bb;
972 /* Callback for for_each_eh_region. Helper for cleanup_dead_labels. */
974 update_eh_label (struct eh_region *region)
976 tree old_label = get_eh_region_tree_label (region);
980 basic_block bb = label_to_block (old_label);
982 /* ??? After optimizing, there may be EH regions with labels
983 that have already been removed from the function body, so
984 there is no basic block for them. */
988 new_label = label_for_bb[bb->index];
989 set_eh_region_tree_label (region, new_label);
993 /* Given LABEL return the first label in the same basic block. */
995 main_block_label (tree label)
997 basic_block bb = label_to_block (label);
999 /* label_to_block possibly inserted undefined label into the chain. */
1000 if (!label_for_bb[bb->index])
1001 label_for_bb[bb->index] = label;
1002 return label_for_bb[bb->index];
1005 /* Cleanup redundant labels. This is a three-step process:
1006 1) Find the leading label for each block.
1007 2) Redirect all references to labels to the leading labels.
1008 3) Cleanup all useless labels. */
1011 cleanup_dead_labels (void)
1014 label_for_bb = xcalloc (last_basic_block, sizeof (tree));
1016 /* Find a suitable label for each block. We use the first user-defined
1017 label if there is one, or otherwise just the first label we see. */
1020 block_stmt_iterator i;
1022 for (i = bsi_start (bb); !bsi_end_p (i); bsi_next (&i))
1024 tree label, stmt = bsi_stmt (i);
1026 if (TREE_CODE (stmt) != LABEL_EXPR)
1029 label = LABEL_EXPR_LABEL (stmt);
1031 /* If we have not yet seen a label for the current block,
1032 remember this one and see if there are more labels. */
1033 if (! label_for_bb[bb->index])
1035 label_for_bb[bb->index] = label;
1039 /* If we did see a label for the current block already, but it
1040 is an artificially created label, replace it if the current
1041 label is a user defined label. */
1042 if (! DECL_ARTIFICIAL (label)
1043 && DECL_ARTIFICIAL (label_for_bb[bb->index]))
1045 label_for_bb[bb->index] = label;
1051 /* Now redirect all jumps/branches to the selected label.
1052 First do so for each block ending in a control statement. */
1055 tree stmt = last_stmt (bb);
1059 switch (TREE_CODE (stmt))
1063 tree true_branch, false_branch;
1065 true_branch = COND_EXPR_THEN (stmt);
1066 false_branch = COND_EXPR_ELSE (stmt);
1068 GOTO_DESTINATION (true_branch)
1069 = main_block_label (GOTO_DESTINATION (true_branch));
1070 GOTO_DESTINATION (false_branch)
1071 = main_block_label (GOTO_DESTINATION (false_branch));
1079 tree vec = SWITCH_LABELS (stmt);
1080 size_t n = TREE_VEC_LENGTH (vec);
1082 /* Replace all destination labels. */
1083 for (i = 0; i < n; ++i)
1085 tree elt = TREE_VEC_ELT (vec, i);
1086 tree label = main_block_label (CASE_LABEL (elt));
1087 CASE_LABEL (elt) = label;
1092 /* We have to handle GOTO_EXPRs until they're removed, and we don't
1093 remove them until after we've created the CFG edges. */
1095 if (! computed_goto_p (stmt))
1097 GOTO_DESTINATION (stmt)
1098 = main_block_label (GOTO_DESTINATION (stmt));
1107 for_each_eh_region (update_eh_label);
1109 /* Finally, purge dead labels. All user-defined labels and labels that
1110 can be the target of non-local gotos are preserved. */
1113 block_stmt_iterator i;
1114 tree label_for_this_bb = label_for_bb[bb->index];
1116 if (! label_for_this_bb)
1119 for (i = bsi_start (bb); !bsi_end_p (i); )
1121 tree label, stmt = bsi_stmt (i);
1123 if (TREE_CODE (stmt) != LABEL_EXPR)
1126 label = LABEL_EXPR_LABEL (stmt);
1128 if (label == label_for_this_bb
1129 || ! DECL_ARTIFICIAL (label)
1130 || DECL_NONLOCAL (label))
1137 free (label_for_bb);
1140 /* Look for blocks ending in a multiway branch (a SWITCH_EXPR in GIMPLE),
1141 and scan the sorted vector of cases. Combine the ones jumping to the
1143 Eg. three separate entries 1: 2: 3: become one entry 1..3: */
1146 group_case_labels (void)
1152 tree stmt = last_stmt (bb);
1153 if (stmt && TREE_CODE (stmt) == SWITCH_EXPR)
1155 tree labels = SWITCH_LABELS (stmt);
1156 int old_size = TREE_VEC_LENGTH (labels);
1157 int i, j, new_size = old_size;
1158 tree default_case = TREE_VEC_ELT (labels, old_size - 1);
1161 /* The default label is always the last case in a switch
1162 statement after gimplification. */
1163 default_label = CASE_LABEL (default_case);
1165 /* Look for possible opportunities to merge cases.
1166 Ignore the last element of the label vector because it
1167 must be the default case. */
1169 while (i < old_size - 1)
1171 tree base_case, base_label, base_high, type;
1172 base_case = TREE_VEC_ELT (labels, i);
1174 gcc_assert (base_case);
1175 base_label = CASE_LABEL (base_case);
1177 /* Discard cases that have the same destination as the
1179 if (base_label == default_label)
1181 TREE_VEC_ELT (labels, i) = NULL_TREE;
1187 type = TREE_TYPE (CASE_LOW (base_case));
1188 base_high = CASE_HIGH (base_case) ?
1189 CASE_HIGH (base_case) : CASE_LOW (base_case);
1191 /* Try to merge case labels. Break out when we reach the end
1192 of the label vector or when we cannot merge the next case
1193 label with the current one. */
1194 while (i < old_size - 1)
1196 tree merge_case = TREE_VEC_ELT (labels, i);
1197 tree merge_label = CASE_LABEL (merge_case);
1198 tree t = int_const_binop (PLUS_EXPR, base_high,
1199 integer_one_node, 1);
1201 /* Merge the cases if they jump to the same place,
1202 and their ranges are consecutive. */
1203 if (merge_label == base_label
1204 && tree_int_cst_equal (CASE_LOW (merge_case), t))
1206 base_high = CASE_HIGH (merge_case) ?
1207 CASE_HIGH (merge_case) : CASE_LOW (merge_case);
1208 CASE_HIGH (base_case) = base_high;
1209 TREE_VEC_ELT (labels, i) = NULL_TREE;
1218 /* Compress the case labels in the label vector, and adjust the
1219 length of the vector. */
1220 for (i = 0, j = 0; i < new_size; i++)
1222 while (! TREE_VEC_ELT (labels, j))
1224 TREE_VEC_ELT (labels, i) = TREE_VEC_ELT (labels, j++);
1226 TREE_VEC_LENGTH (labels) = new_size;
1231 /* Checks whether we can merge block B into block A. */
1234 tree_can_merge_blocks_p (basic_block a, basic_block b)
1237 block_stmt_iterator bsi;
1239 if (EDGE_COUNT (a->succs) != 1)
1242 if (EDGE_SUCC (a, 0)->flags & EDGE_ABNORMAL)
1245 if (EDGE_SUCC (a, 0)->dest != b)
1248 if (EDGE_COUNT (b->preds) > 1)
1251 if (b == EXIT_BLOCK_PTR)
1254 /* If A ends by a statement causing exceptions or something similar, we
1255 cannot merge the blocks. */
1256 stmt = last_stmt (a);
1257 if (stmt && stmt_ends_bb_p (stmt))
1260 /* Do not allow a block with only a non-local label to be merged. */
1261 if (stmt && TREE_CODE (stmt) == LABEL_EXPR
1262 && DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)))
1265 /* There may be no phi nodes at the start of b. Most of these degenerate
1266 phi nodes should be cleaned up by kill_redundant_phi_nodes. */
1270 /* Do not remove user labels. */
1271 for (bsi = bsi_start (b); !bsi_end_p (bsi); bsi_next (&bsi))
1273 stmt = bsi_stmt (bsi);
1274 if (TREE_CODE (stmt) != LABEL_EXPR)
1276 if (!DECL_ARTIFICIAL (LABEL_EXPR_LABEL (stmt)))
1284 /* Merge block B into block A. */
1287 tree_merge_blocks (basic_block a, basic_block b)
1289 block_stmt_iterator bsi;
1290 tree_stmt_iterator last;
1293 fprintf (dump_file, "Merging blocks %d and %d\n", a->index, b->index);
1295 /* Ensure that B follows A. */
1296 move_block_after (b, a);
1298 gcc_assert (EDGE_SUCC (a, 0)->flags & EDGE_FALLTHRU);
1299 gcc_assert (!last_stmt (a) || !stmt_ends_bb_p (last_stmt (a)));
1301 /* Remove labels from B and set bb_for_stmt to A for other statements. */
1302 for (bsi = bsi_start (b); !bsi_end_p (bsi);)
1304 if (TREE_CODE (bsi_stmt (bsi)) == LABEL_EXPR)
1306 tree label = bsi_stmt (bsi);
1309 /* Now that we can thread computed gotos, we might have
1310 a situation where we have a forced label in block B
1311 However, the label at the start of block B might still be
1312 used in other ways (think about the runtime checking for
1313 Fortran assigned gotos). So we can not just delete the
1314 label. Instead we move the label to the start of block A. */
1315 if (FORCED_LABEL (LABEL_EXPR_LABEL (label)))
1317 block_stmt_iterator dest_bsi = bsi_start (a);
1318 bsi_insert_before (&dest_bsi, label, BSI_NEW_STMT);
1323 set_bb_for_stmt (bsi_stmt (bsi), a);
1328 /* Merge the chains. */
1329 last = tsi_last (a->stmt_list);
1330 tsi_link_after (&last, b->stmt_list, TSI_NEW_STMT);
1331 b->stmt_list = NULL;
1335 /* Walk the function tree removing unnecessary statements.
1337 * Empty statement nodes are removed
1339 * Unnecessary TRY_FINALLY and TRY_CATCH blocks are removed
1341 * Unnecessary COND_EXPRs are removed
1343 * Some unnecessary BIND_EXPRs are removed
1345 Clearly more work could be done. The trick is doing the analysis
1346 and removal fast enough to be a net improvement in compile times.
1348 Note that when we remove a control structure such as a COND_EXPR
1349 BIND_EXPR, or TRY block, we will need to repeat this optimization pass
1350 to ensure we eliminate all the useless code. */
1361 static void remove_useless_stmts_1 (tree *, struct rus_data *);
1364 remove_useless_stmts_warn_notreached (tree stmt)
1366 if (EXPR_HAS_LOCATION (stmt))
1368 location_t loc = EXPR_LOCATION (stmt);
1369 if (LOCATION_LINE (loc) > 0)
1371 warning ("%Hwill never be executed", &loc);
1376 switch (TREE_CODE (stmt))
1378 case STATEMENT_LIST:
1380 tree_stmt_iterator i;
1381 for (i = tsi_start (stmt); !tsi_end_p (i); tsi_next (&i))
1382 if (remove_useless_stmts_warn_notreached (tsi_stmt (i)))
1388 if (remove_useless_stmts_warn_notreached (COND_EXPR_COND (stmt)))
1390 if (remove_useless_stmts_warn_notreached (COND_EXPR_THEN (stmt)))
1392 if (remove_useless_stmts_warn_notreached (COND_EXPR_ELSE (stmt)))
1396 case TRY_FINALLY_EXPR:
1397 case TRY_CATCH_EXPR:
1398 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt, 0)))
1400 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt, 1)))
1405 return remove_useless_stmts_warn_notreached (CATCH_BODY (stmt));
1406 case EH_FILTER_EXPR:
1407 return remove_useless_stmts_warn_notreached (EH_FILTER_FAILURE (stmt));
1409 return remove_useless_stmts_warn_notreached (BIND_EXPR_BLOCK (stmt));
1412 /* Not a live container. */
1420 remove_useless_stmts_cond (tree *stmt_p, struct rus_data *data)
1422 tree then_clause, else_clause, cond;
1423 bool save_has_label, then_has_label, else_has_label;
1425 save_has_label = data->has_label;
1426 data->has_label = false;
1427 data->last_goto = NULL;
1429 remove_useless_stmts_1 (&COND_EXPR_THEN (*stmt_p), data);
1431 then_has_label = data->has_label;
1432 data->has_label = false;
1433 data->last_goto = NULL;
1435 remove_useless_stmts_1 (&COND_EXPR_ELSE (*stmt_p), data);
1437 else_has_label = data->has_label;
1438 data->has_label = save_has_label | then_has_label | else_has_label;
1440 then_clause = COND_EXPR_THEN (*stmt_p);
1441 else_clause = COND_EXPR_ELSE (*stmt_p);
1442 cond = fold (COND_EXPR_COND (*stmt_p));
1444 /* If neither arm does anything at all, we can remove the whole IF. */
1445 if (!TREE_SIDE_EFFECTS (then_clause) && !TREE_SIDE_EFFECTS (else_clause))
1447 *stmt_p = build_empty_stmt ();
1448 data->repeat = true;
1451 /* If there are no reachable statements in an arm, then we can
1452 zap the entire conditional. */
1453 else if (integer_nonzerop (cond) && !else_has_label)
1455 if (warn_notreached)
1456 remove_useless_stmts_warn_notreached (else_clause);
1457 *stmt_p = then_clause;
1458 data->repeat = true;
1460 else if (integer_zerop (cond) && !then_has_label)
1462 if (warn_notreached)
1463 remove_useless_stmts_warn_notreached (then_clause);
1464 *stmt_p = else_clause;
1465 data->repeat = true;
1468 /* Check a couple of simple things on then/else with single stmts. */
1471 tree then_stmt = expr_only (then_clause);
1472 tree else_stmt = expr_only (else_clause);
1474 /* Notice branches to a common destination. */
1475 if (then_stmt && else_stmt
1476 && TREE_CODE (then_stmt) == GOTO_EXPR
1477 && TREE_CODE (else_stmt) == GOTO_EXPR
1478 && (GOTO_DESTINATION (then_stmt) == GOTO_DESTINATION (else_stmt)))
1480 *stmt_p = then_stmt;
1481 data->repeat = true;
1484 /* If the THEN/ELSE clause merely assigns a value to a variable or
1485 parameter which is already known to contain that value, then
1486 remove the useless THEN/ELSE clause. */
1487 else if (TREE_CODE (cond) == VAR_DECL || TREE_CODE (cond) == PARM_DECL)
1490 && TREE_CODE (else_stmt) == MODIFY_EXPR
1491 && TREE_OPERAND (else_stmt, 0) == cond
1492 && integer_zerop (TREE_OPERAND (else_stmt, 1)))
1493 COND_EXPR_ELSE (*stmt_p) = alloc_stmt_list ();
1495 else if ((TREE_CODE (cond) == EQ_EXPR || TREE_CODE (cond) == NE_EXPR)
1496 && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL
1497 || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL)
1498 && TREE_CONSTANT (TREE_OPERAND (cond, 1)))
1500 tree stmt = (TREE_CODE (cond) == EQ_EXPR
1501 ? then_stmt : else_stmt);
1502 tree *location = (TREE_CODE (cond) == EQ_EXPR
1503 ? &COND_EXPR_THEN (*stmt_p)
1504 : &COND_EXPR_ELSE (*stmt_p));
1507 && TREE_CODE (stmt) == MODIFY_EXPR
1508 && TREE_OPERAND (stmt, 0) == TREE_OPERAND (cond, 0)
1509 && TREE_OPERAND (stmt, 1) == TREE_OPERAND (cond, 1))
1510 *location = alloc_stmt_list ();
1514 /* Protect GOTOs in the arm of COND_EXPRs from being removed. They
1515 would be re-introduced during lowering. */
1516 data->last_goto = NULL;
1521 remove_useless_stmts_tf (tree *stmt_p, struct rus_data *data)
1523 bool save_may_branch, save_may_throw;
1524 bool this_may_branch, this_may_throw;
1526 /* Collect may_branch and may_throw information for the body only. */
1527 save_may_branch = data->may_branch;
1528 save_may_throw = data->may_throw;
1529 data->may_branch = false;
1530 data->may_throw = false;
1531 data->last_goto = NULL;
1533 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 0), data);
1535 this_may_branch = data->may_branch;
1536 this_may_throw = data->may_throw;
1537 data->may_branch |= save_may_branch;
1538 data->may_throw |= save_may_throw;
1539 data->last_goto = NULL;
1541 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 1), data);
1543 /* If the body is empty, then we can emit the FINALLY block without
1544 the enclosing TRY_FINALLY_EXPR. */
1545 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 0)))
1547 *stmt_p = TREE_OPERAND (*stmt_p, 1);
1548 data->repeat = true;
1551 /* If the handler is empty, then we can emit the TRY block without
1552 the enclosing TRY_FINALLY_EXPR. */
1553 else if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 1)))
1555 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1556 data->repeat = true;
1559 /* If the body neither throws, nor branches, then we can safely
1560 string the TRY and FINALLY blocks together. */
1561 else if (!this_may_branch && !this_may_throw)
1563 tree stmt = *stmt_p;
1564 *stmt_p = TREE_OPERAND (stmt, 0);
1565 append_to_statement_list (TREE_OPERAND (stmt, 1), stmt_p);
1566 data->repeat = true;
1572 remove_useless_stmts_tc (tree *stmt_p, struct rus_data *data)
1574 bool save_may_throw, this_may_throw;
1575 tree_stmt_iterator i;
1578 /* Collect may_throw information for the body only. */
1579 save_may_throw = data->may_throw;
1580 data->may_throw = false;
1581 data->last_goto = NULL;
1583 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 0), data);
1585 this_may_throw = data->may_throw;
1586 data->may_throw = save_may_throw;
1588 /* If the body cannot throw, then we can drop the entire TRY_CATCH_EXPR. */
1589 if (!this_may_throw)
1591 if (warn_notreached)
1592 remove_useless_stmts_warn_notreached (TREE_OPERAND (*stmt_p, 1));
1593 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1594 data->repeat = true;
1598 /* Process the catch clause specially. We may be able to tell that
1599 no exceptions propagate past this point. */
1601 this_may_throw = true;
1602 i = tsi_start (TREE_OPERAND (*stmt_p, 1));
1603 stmt = tsi_stmt (i);
1604 data->last_goto = NULL;
1606 switch (TREE_CODE (stmt))
1609 for (; !tsi_end_p (i); tsi_next (&i))
1611 stmt = tsi_stmt (i);
1612 /* If we catch all exceptions, then the body does not
1613 propagate exceptions past this point. */
1614 if (CATCH_TYPES (stmt) == NULL)
1615 this_may_throw = false;
1616 data->last_goto = NULL;
1617 remove_useless_stmts_1 (&CATCH_BODY (stmt), data);
1621 case EH_FILTER_EXPR:
1622 if (EH_FILTER_MUST_NOT_THROW (stmt))
1623 this_may_throw = false;
1624 else if (EH_FILTER_TYPES (stmt) == NULL)
1625 this_may_throw = false;
1626 remove_useless_stmts_1 (&EH_FILTER_FAILURE (stmt), data);
1630 /* Otherwise this is a cleanup. */
1631 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 1), data);
1633 /* If the cleanup is empty, then we can emit the TRY block without
1634 the enclosing TRY_CATCH_EXPR. */
1635 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 1)))
1637 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1638 data->repeat = true;
1642 data->may_throw |= this_may_throw;
1647 remove_useless_stmts_bind (tree *stmt_p, struct rus_data *data)
1651 /* First remove anything underneath the BIND_EXPR. */
1652 remove_useless_stmts_1 (&BIND_EXPR_BODY (*stmt_p), data);
1654 /* If the BIND_EXPR has no variables, then we can pull everything
1655 up one level and remove the BIND_EXPR, unless this is the toplevel
1656 BIND_EXPR for the current function or an inlined function.
1658 When this situation occurs we will want to apply this
1659 optimization again. */
1660 block = BIND_EXPR_BLOCK (*stmt_p);
1661 if (BIND_EXPR_VARS (*stmt_p) == NULL_TREE
1662 && *stmt_p != DECL_SAVED_TREE (current_function_decl)
1664 || ! BLOCK_ABSTRACT_ORIGIN (block)
1665 || (TREE_CODE (BLOCK_ABSTRACT_ORIGIN (block))
1668 *stmt_p = BIND_EXPR_BODY (*stmt_p);
1669 data->repeat = true;
1675 remove_useless_stmts_goto (tree *stmt_p, struct rus_data *data)
1677 tree dest = GOTO_DESTINATION (*stmt_p);
1679 data->may_branch = true;
1680 data->last_goto = NULL;
1682 /* Record the last goto expr, so that we can delete it if unnecessary. */
1683 if (TREE_CODE (dest) == LABEL_DECL)
1684 data->last_goto = stmt_p;
1689 remove_useless_stmts_label (tree *stmt_p, struct rus_data *data)
1691 tree label = LABEL_EXPR_LABEL (*stmt_p);
1693 data->has_label = true;
1695 /* We do want to jump across non-local label receiver code. */
1696 if (DECL_NONLOCAL (label))
1697 data->last_goto = NULL;
1699 else if (data->last_goto && GOTO_DESTINATION (*data->last_goto) == label)
1701 *data->last_goto = build_empty_stmt ();
1702 data->repeat = true;
1705 /* ??? Add something here to delete unused labels. */
1709 /* If the function is "const" or "pure", then clear TREE_SIDE_EFFECTS on its
1710 decl. This allows us to eliminate redundant or useless
1711 calls to "const" functions.
1713 Gimplifier already does the same operation, but we may notice functions
1714 being const and pure once their calls has been gimplified, so we need
1715 to update the flag. */
1718 update_call_expr_flags (tree call)
1720 tree decl = get_callee_fndecl (call);
1723 if (call_expr_flags (call) & (ECF_CONST | ECF_PURE))
1724 TREE_SIDE_EFFECTS (call) = 0;
1725 if (TREE_NOTHROW (decl))
1726 TREE_NOTHROW (call) = 1;
1730 /* T is CALL_EXPR. Set current_function_calls_* flags. */
1733 notice_special_calls (tree t)
1735 int flags = call_expr_flags (t);
1737 if (flags & ECF_MAY_BE_ALLOCA)
1738 current_function_calls_alloca = true;
1739 if (flags & ECF_RETURNS_TWICE)
1740 current_function_calls_setjmp = true;
1744 /* Clear flags set by notice_special_calls. Used by dead code removal
1745 to update the flags. */
1748 clear_special_calls (void)
1750 current_function_calls_alloca = false;
1751 current_function_calls_setjmp = false;
1756 remove_useless_stmts_1 (tree *tp, struct rus_data *data)
1760 switch (TREE_CODE (t))
1763 remove_useless_stmts_cond (tp, data);
1766 case TRY_FINALLY_EXPR:
1767 remove_useless_stmts_tf (tp, data);
1770 case TRY_CATCH_EXPR:
1771 remove_useless_stmts_tc (tp, data);
1775 remove_useless_stmts_bind (tp, data);
1779 remove_useless_stmts_goto (tp, data);
1783 remove_useless_stmts_label (tp, data);
1788 data->last_goto = NULL;
1789 data->may_branch = true;
1794 data->last_goto = NULL;
1795 notice_special_calls (t);
1796 update_call_expr_flags (t);
1797 if (tree_could_throw_p (t))
1798 data->may_throw = true;
1802 data->last_goto = NULL;
1804 op = get_call_expr_in (t);
1807 update_call_expr_flags (op);
1808 notice_special_calls (op);
1810 if (tree_could_throw_p (t))
1811 data->may_throw = true;
1814 case STATEMENT_LIST:
1816 tree_stmt_iterator i = tsi_start (t);
1817 while (!tsi_end_p (i))
1820 if (IS_EMPTY_STMT (t))
1826 remove_useless_stmts_1 (tsi_stmt_ptr (i), data);
1829 if (TREE_CODE (t) == STATEMENT_LIST)
1831 tsi_link_before (&i, t, TSI_SAME_STMT);
1841 data->last_goto = NULL;
1845 data->last_goto = NULL;
1851 remove_useless_stmts (void)
1853 struct rus_data data;
1855 clear_special_calls ();
1859 memset (&data, 0, sizeof (data));
1860 remove_useless_stmts_1 (&DECL_SAVED_TREE (current_function_decl), &data);
1862 while (data.repeat);
1866 struct tree_opt_pass pass_remove_useless_stmts =
1868 "useless", /* name */
1870 remove_useless_stmts, /* execute */
1873 0, /* static_pass_number */
1875 PROP_gimple_any, /* properties_required */
1876 0, /* properties_provided */
1877 0, /* properties_destroyed */
1878 0, /* todo_flags_start */
1879 TODO_dump_func, /* todo_flags_finish */
1884 /* Remove obviously useless statements in basic block BB. */
1887 cfg_remove_useless_stmts_bb (basic_block bb)
1889 block_stmt_iterator bsi;
1890 tree stmt = NULL_TREE;
1891 tree cond, var = NULL_TREE, val = NULL_TREE;
1892 struct var_ann_d *ann;
1894 /* Check whether we come here from a condition, and if so, get the
1896 if (EDGE_COUNT (bb->preds) != 1
1897 || !(EDGE_PRED (bb, 0)->flags & (EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
1900 cond = COND_EXPR_COND (last_stmt (EDGE_PRED (bb, 0)->src));
1902 if (TREE_CODE (cond) == VAR_DECL || TREE_CODE (cond) == PARM_DECL)
1905 val = (EDGE_PRED (bb, 0)->flags & EDGE_FALSE_VALUE
1906 ? boolean_false_node : boolean_true_node);
1908 else if (TREE_CODE (cond) == TRUTH_NOT_EXPR
1909 && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL
1910 || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL))
1912 var = TREE_OPERAND (cond, 0);
1913 val = (EDGE_PRED (bb, 0)->flags & EDGE_FALSE_VALUE
1914 ? boolean_true_node : boolean_false_node);
1918 if (EDGE_PRED (bb, 0)->flags & EDGE_FALSE_VALUE)
1919 cond = invert_truthvalue (cond);
1920 if (TREE_CODE (cond) == EQ_EXPR
1921 && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL
1922 || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL)
1923 && (TREE_CODE (TREE_OPERAND (cond, 1)) == VAR_DECL
1924 || TREE_CODE (TREE_OPERAND (cond, 1)) == PARM_DECL
1925 || TREE_CONSTANT (TREE_OPERAND (cond, 1))))
1927 var = TREE_OPERAND (cond, 0);
1928 val = TREE_OPERAND (cond, 1);
1934 /* Only work for normal local variables. */
1935 ann = var_ann (var);
1938 || TREE_ADDRESSABLE (var))
1941 if (! TREE_CONSTANT (val))
1943 ann = var_ann (val);
1946 || TREE_ADDRESSABLE (val))
1950 /* Ignore floating point variables, since comparison behaves weird for
1952 if (FLOAT_TYPE_P (TREE_TYPE (var)))
1955 for (bsi = bsi_start (bb); !bsi_end_p (bsi);)
1957 stmt = bsi_stmt (bsi);
1959 /* If the THEN/ELSE clause merely assigns a value to a variable/parameter
1960 which is already known to contain that value, then remove the useless
1961 THEN/ELSE clause. */
1962 if (TREE_CODE (stmt) == MODIFY_EXPR
1963 && TREE_OPERAND (stmt, 0) == var
1964 && operand_equal_p (val, TREE_OPERAND (stmt, 1), 0))
1970 /* Invalidate the var if we encounter something that could modify it.
1971 Likewise for the value it was previously set to. Note that we only
1972 consider values that are either a VAR_DECL or PARM_DECL so we
1973 can test for conflict very simply. */
1974 if (TREE_CODE (stmt) == ASM_EXPR
1975 || (TREE_CODE (stmt) == MODIFY_EXPR
1976 && (TREE_OPERAND (stmt, 0) == var
1977 || TREE_OPERAND (stmt, 0) == val)))
1985 /* A CFG-aware version of remove_useless_stmts. */
1988 cfg_remove_useless_stmts (void)
1992 #ifdef ENABLE_CHECKING
1993 verify_flow_info ();
1998 cfg_remove_useless_stmts_bb (bb);
2003 /* Remove PHI nodes associated with basic block BB and all edges out of BB. */
2006 remove_phi_nodes_and_edges_for_unreachable_block (basic_block bb)
2010 /* Since this block is no longer reachable, we can just delete all
2011 of its PHI nodes. */
2012 phi = phi_nodes (bb);
2015 tree next = PHI_CHAIN (phi);
2016 remove_phi_node (phi, NULL_TREE);
2020 /* Remove edges to BB's successors. */
2021 while (EDGE_COUNT (bb->succs) > 0)
2022 remove_edge (EDGE_SUCC (bb, 0));
2026 /* Remove statements of basic block BB. */
2029 remove_bb (basic_block bb)
2031 block_stmt_iterator i;
2032 #ifdef USE_MAPPED_LOCATION
2033 source_location loc = UNKNOWN_LOCATION;
2035 source_locus loc = 0;
2040 fprintf (dump_file, "Removing basic block %d\n", bb->index);
2041 if (dump_flags & TDF_DETAILS)
2043 dump_bb (bb, dump_file, 0);
2044 fprintf (dump_file, "\n");
2048 /* Remove all the instructions in the block. */
2049 for (i = bsi_start (bb); !bsi_end_p (i);)
2051 tree stmt = bsi_stmt (i);
2052 if (TREE_CODE (stmt) == LABEL_EXPR
2053 && FORCED_LABEL (LABEL_EXPR_LABEL (stmt)))
2055 basic_block new_bb = bb->prev_bb;
2056 block_stmt_iterator new_bsi = bsi_start (new_bb);
2059 bsi_insert_before (&new_bsi, stmt, BSI_NEW_STMT);
2063 release_defs (stmt);
2065 set_bb_for_stmt (stmt, NULL);
2069 /* Don't warn for removed gotos. Gotos are often removed due to
2070 jump threading, thus resulting in bogus warnings. Not great,
2071 since this way we lose warnings for gotos in the original
2072 program that are indeed unreachable. */
2073 if (TREE_CODE (stmt) != GOTO_EXPR && EXPR_HAS_LOCATION (stmt) && !loc)
2075 #ifdef USE_MAPPED_LOCATION
2076 if (EXPR_HAS_LOCATION (stmt))
2077 loc = EXPR_LOCATION (stmt);
2080 t = EXPR_LOCUS (stmt);
2081 if (t && LOCATION_LINE (*t) > 0)
2087 /* If requested, give a warning that the first statement in the
2088 block is unreachable. We walk statements backwards in the
2089 loop above, so the last statement we process is the first statement
2091 #ifdef USE_MAPPED_LOCATION
2092 if (warn_notreached && loc != UNKNOWN_LOCATION)
2093 warning ("%Hwill never be executed", &loc);
2095 if (warn_notreached && loc)
2096 warning ("%Hwill never be executed", loc);
2099 remove_phi_nodes_and_edges_for_unreachable_block (bb);
2102 /* A list of all the noreturn calls passed to modify_stmt.
2103 cleanup_control_flow uses it to detect cases where a mid-block
2104 indirect call has been turned into a noreturn call. When this
2105 happens, all the instructions after the call are no longer
2106 reachable and must be deleted as dead. */
2108 VEC(tree) *modified_noreturn_calls;
2110 /* Try to remove superfluous control structures. */
2113 cleanup_control_flow (void)
2116 block_stmt_iterator bsi;
2117 bool retval = false;
2120 /* Detect cases where a mid-block call is now known not to return. */
2121 while (VEC_length (tree, modified_noreturn_calls))
2123 stmt = VEC_pop (tree, modified_noreturn_calls);
2124 bb = bb_for_stmt (stmt);
2125 if (bb != NULL && last_stmt (bb) != stmt && noreturn_call_p (stmt))
2126 split_block (bb, stmt);
2131 bsi = bsi_last (bb);
2133 if (bsi_end_p (bsi))
2136 stmt = bsi_stmt (bsi);
2137 if (TREE_CODE (stmt) == COND_EXPR
2138 || TREE_CODE (stmt) == SWITCH_EXPR)
2139 retval |= cleanup_control_expr_graph (bb, bsi);
2141 /* If we had a computed goto which has a compile-time determinable
2142 destination, then we can eliminate the goto. */
2143 if (TREE_CODE (stmt) == GOTO_EXPR
2144 && TREE_CODE (GOTO_DESTINATION (stmt)) == ADDR_EXPR
2145 && TREE_CODE (TREE_OPERAND (GOTO_DESTINATION (stmt), 0)) == LABEL_DECL)
2150 basic_block target_block;
2152 /* First look at all the outgoing edges. Delete any outgoing
2153 edges which do not go to the right block. For the one
2154 edge which goes to the right block, fix up its flags. */
2155 label = TREE_OPERAND (GOTO_DESTINATION (stmt), 0);
2156 target_block = label_to_block (label);
2157 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2159 if (e->dest != target_block)
2163 /* Turn off the EDGE_ABNORMAL flag. */
2164 EDGE_SUCC (bb, 0)->flags &= ~EDGE_ABNORMAL;
2166 /* And set EDGE_FALLTHRU. */
2167 EDGE_SUCC (bb, 0)->flags |= EDGE_FALLTHRU;
2172 /* Remove the GOTO_EXPR as it is not needed. The CFG has all the
2173 relevant information we need. */
2178 /* Check for indirect calls that have been turned into
2180 if (noreturn_call_p (stmt) && remove_fallthru_edge (bb->succs))
2182 free_dominance_info (CDI_DOMINATORS);
2190 /* Disconnect an unreachable block in the control expression starting
2194 cleanup_control_expr_graph (basic_block bb, block_stmt_iterator bsi)
2197 bool retval = false;
2198 tree expr = bsi_stmt (bsi), val;
2200 if (EDGE_COUNT (bb->succs) > 1)
2205 switch (TREE_CODE (expr))
2208 val = COND_EXPR_COND (expr);
2212 val = SWITCH_COND (expr);
2213 if (TREE_CODE (val) != INTEGER_CST)
2221 taken_edge = find_taken_edge (bb, val);
2225 /* Remove all the edges except the one that is always executed. */
2226 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2228 if (e != taken_edge)
2230 taken_edge->probability += e->probability;
2231 taken_edge->count += e->count;
2238 if (taken_edge->probability > REG_BR_PROB_BASE)
2239 taken_edge->probability = REG_BR_PROB_BASE;
2242 taken_edge = EDGE_SUCC (bb, 0);
2245 taken_edge->flags = EDGE_FALLTHRU;
2247 /* We removed some paths from the cfg. */
2248 free_dominance_info (CDI_DOMINATORS);
2253 /* Remove any fallthru edge from EV. Return true if an edge was removed. */
2256 remove_fallthru_edge (VEC(edge) *ev)
2261 FOR_EACH_EDGE (e, ei, ev)
2262 if ((e->flags & EDGE_FALLTHRU) != 0)
2270 /* Given a basic block BB ending with COND_EXPR or SWITCH_EXPR, and a
2271 predicate VAL, return the edge that will be taken out of the block.
2272 If VAL does not match a unique edge, NULL is returned. */
2275 find_taken_edge (basic_block bb, tree val)
2279 stmt = last_stmt (bb);
2282 gcc_assert (is_ctrl_stmt (stmt));
2285 if (! is_gimple_min_invariant (val))
2288 if (TREE_CODE (stmt) == COND_EXPR)
2289 return find_taken_edge_cond_expr (bb, val);
2291 if (TREE_CODE (stmt) == SWITCH_EXPR)
2292 return find_taken_edge_switch_expr (bb, val);
2294 if (computed_goto_p (stmt))
2295 return find_taken_edge_computed_goto (bb, TREE_OPERAND( val, 0));
2300 /* Given a constant value VAL and the entry block BB to a GOTO_EXPR
2301 statement, determine which of the outgoing edges will be taken out of the
2302 block. Return NULL if either edge may be taken. */
2305 find_taken_edge_computed_goto (basic_block bb, tree val)
2310 dest = label_to_block (val);
2313 e = find_edge (bb, dest);
2314 gcc_assert (e != NULL);
2320 /* Given a constant value VAL and the entry block BB to a COND_EXPR
2321 statement, determine which of the two edges will be taken out of the
2322 block. Return NULL if either edge may be taken. */
2325 find_taken_edge_cond_expr (basic_block bb, tree val)
2327 edge true_edge, false_edge;
2329 extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
2331 /* Otherwise, try to determine which branch of the if() will be taken.
2332 If VAL is a constant but it can't be reduced to a 0 or a 1, then
2333 we don't really know which edge will be taken at runtime. This
2334 may happen when comparing addresses (e.g., if (&var1 == 4)). */
2335 if (integer_nonzerop (val))
2337 else if (integer_zerop (val))
2344 /* Given an INTEGER_CST VAL and the entry block BB to a SWITCH_EXPR
2345 statement, determine which edge will be taken out of the block. Return
2346 NULL if any edge may be taken. */
2349 find_taken_edge_switch_expr (basic_block bb, tree val)
2351 tree switch_expr, taken_case;
2352 basic_block dest_bb;
2355 switch_expr = last_stmt (bb);
2356 taken_case = find_case_label_for_value (switch_expr, val);
2357 dest_bb = label_to_block (CASE_LABEL (taken_case));
2359 e = find_edge (bb, dest_bb);
2365 /* Return the CASE_LABEL_EXPR that SWITCH_EXPR will take for VAL.
2366 We can make optimal use here of the fact that the case labels are
2367 sorted: We can do a binary search for a case matching VAL. */
2370 find_case_label_for_value (tree switch_expr, tree val)
2372 tree vec = SWITCH_LABELS (switch_expr);
2373 size_t low, high, n = TREE_VEC_LENGTH (vec);
2374 tree default_case = TREE_VEC_ELT (vec, n - 1);
2376 for (low = -1, high = n - 1; high - low > 1; )
2378 size_t i = (high + low) / 2;
2379 tree t = TREE_VEC_ELT (vec, i);
2382 /* Cache the result of comparing CASE_LOW and val. */
2383 cmp = tree_int_cst_compare (CASE_LOW (t), val);
2390 if (CASE_HIGH (t) == NULL)
2392 /* A singe-valued case label. */
2398 /* A case range. We can only handle integer ranges. */
2399 if (cmp <= 0 && tree_int_cst_compare (CASE_HIGH (t), val) >= 0)
2404 return default_case;
2408 /* If all the PHI nodes in DEST have alternatives for E1 and E2 and
2409 those alternatives are equal in each of the PHI nodes, then return
2410 true, else return false. */
2413 phi_alternatives_equal (basic_block dest, edge e1, edge e2)
2415 int n1 = e1->dest_idx;
2416 int n2 = e2->dest_idx;
2419 for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi))
2421 tree val1 = PHI_ARG_DEF (phi, n1);
2422 tree val2 = PHI_ARG_DEF (phi, n2);
2424 gcc_assert (val1 != NULL_TREE);
2425 gcc_assert (val2 != NULL_TREE);
2427 if (!operand_equal_for_phi_arg_p (val1, val2))
2435 /*---------------------------------------------------------------------------
2437 ---------------------------------------------------------------------------*/
2439 /* Dump tree-specific information of block BB to file OUTF. */
2442 tree_dump_bb (basic_block bb, FILE *outf, int indent)
2444 dump_generic_bb (outf, bb, indent, TDF_VOPS);
2448 /* Dump a basic block on stderr. */
2451 debug_tree_bb (basic_block bb)
2453 dump_bb (bb, stderr, 0);
2457 /* Dump basic block with index N on stderr. */
2460 debug_tree_bb_n (int n)
2462 debug_tree_bb (BASIC_BLOCK (n));
2463 return BASIC_BLOCK (n);
2467 /* Dump the CFG on stderr.
2469 FLAGS are the same used by the tree dumping functions
2470 (see TDF_* in tree.h). */
2473 debug_tree_cfg (int flags)
2475 dump_tree_cfg (stderr, flags);
2479 /* Dump the program showing basic block boundaries on the given FILE.
2481 FLAGS are the same used by the tree dumping functions (see TDF_* in
2485 dump_tree_cfg (FILE *file, int flags)
2487 if (flags & TDF_DETAILS)
2489 const char *funcname
2490 = lang_hooks.decl_printable_name (current_function_decl, 2);
2493 fprintf (file, ";; Function %s\n\n", funcname);
2494 fprintf (file, ";; \n%d basic blocks, %d edges, last basic block %d.\n\n",
2495 n_basic_blocks, n_edges, last_basic_block);
2497 brief_dump_cfg (file);
2498 fprintf (file, "\n");
2501 if (flags & TDF_STATS)
2502 dump_cfg_stats (file);
2504 dump_function_to_file (current_function_decl, file, flags | TDF_BLOCKS);
2508 /* Dump CFG statistics on FILE. */
2511 dump_cfg_stats (FILE *file)
2513 static long max_num_merged_labels = 0;
2514 unsigned long size, total = 0;
2517 const char * const fmt_str = "%-30s%-13s%12s\n";
2518 const char * const fmt_str_1 = "%-30s%13d%11lu%c\n";
2519 const char * const fmt_str_3 = "%-43s%11lu%c\n";
2520 const char *funcname
2521 = lang_hooks.decl_printable_name (current_function_decl, 2);
2524 fprintf (file, "\nCFG Statistics for %s\n\n", funcname);
2526 fprintf (file, "---------------------------------------------------------\n");
2527 fprintf (file, fmt_str, "", " Number of ", "Memory");
2528 fprintf (file, fmt_str, "", " instances ", "used ");
2529 fprintf (file, "---------------------------------------------------------\n");
2531 size = n_basic_blocks * sizeof (struct basic_block_def);
2533 fprintf (file, fmt_str_1, "Basic blocks", n_basic_blocks,
2534 SCALE (size), LABEL (size));
2538 n_edges += EDGE_COUNT (bb->succs);
2539 size = n_edges * sizeof (struct edge_def);
2541 fprintf (file, fmt_str_1, "Edges", n_edges, SCALE (size), LABEL (size));
2543 size = n_basic_blocks * sizeof (struct bb_ann_d);
2545 fprintf (file, fmt_str_1, "Basic block annotations", n_basic_blocks,
2546 SCALE (size), LABEL (size));
2548 fprintf (file, "---------------------------------------------------------\n");
2549 fprintf (file, fmt_str_3, "Total memory used by CFG data", SCALE (total),
2551 fprintf (file, "---------------------------------------------------------\n");
2552 fprintf (file, "\n");
2554 if (cfg_stats.num_merged_labels > max_num_merged_labels)
2555 max_num_merged_labels = cfg_stats.num_merged_labels;
2557 fprintf (file, "Coalesced label blocks: %ld (Max so far: %ld)\n",
2558 cfg_stats.num_merged_labels, max_num_merged_labels);
2560 fprintf (file, "\n");
2564 /* Dump CFG statistics on stderr. Keep extern so that it's always
2565 linked in the final executable. */
2568 debug_cfg_stats (void)
2570 dump_cfg_stats (stderr);
2574 /* Dump the flowgraph to a .vcg FILE. */
2577 tree_cfg2vcg (FILE *file)
2582 const char *funcname
2583 = lang_hooks.decl_printable_name (current_function_decl, 2);
2585 /* Write the file header. */
2586 fprintf (file, "graph: { title: \"%s\"\n", funcname);
2587 fprintf (file, "node: { title: \"ENTRY\" label: \"ENTRY\" }\n");
2588 fprintf (file, "node: { title: \"EXIT\" label: \"EXIT\" }\n");
2590 /* Write blocks and edges. */
2591 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
2593 fprintf (file, "edge: { sourcename: \"ENTRY\" targetname: \"%d\"",
2596 if (e->flags & EDGE_FAKE)
2597 fprintf (file, " linestyle: dotted priority: 10");
2599 fprintf (file, " linestyle: solid priority: 100");
2601 fprintf (file, " }\n");
2607 enum tree_code head_code, end_code;
2608 const char *head_name, *end_name;
2611 tree first = first_stmt (bb);
2612 tree last = last_stmt (bb);
2616 head_code = TREE_CODE (first);
2617 head_name = tree_code_name[head_code];
2618 head_line = get_lineno (first);
2621 head_name = "no-statement";
2625 end_code = TREE_CODE (last);
2626 end_name = tree_code_name[end_code];
2627 end_line = get_lineno (last);
2630 end_name = "no-statement";
2632 fprintf (file, "node: { title: \"%d\" label: \"#%d\\n%s (%d)\\n%s (%d)\"}\n",
2633 bb->index, bb->index, head_name, head_line, end_name,
2636 FOR_EACH_EDGE (e, ei, bb->succs)
2638 if (e->dest == EXIT_BLOCK_PTR)
2639 fprintf (file, "edge: { sourcename: \"%d\" targetname: \"EXIT\"", bb->index);
2641 fprintf (file, "edge: { sourcename: \"%d\" targetname: \"%d\"", bb->index, e->dest->index);
2643 if (e->flags & EDGE_FAKE)
2644 fprintf (file, " priority: 10 linestyle: dotted");
2646 fprintf (file, " priority: 100 linestyle: solid");
2648 fprintf (file, " }\n");
2651 if (bb->next_bb != EXIT_BLOCK_PTR)
2655 fputs ("}\n\n", file);
2660 /*---------------------------------------------------------------------------
2661 Miscellaneous helpers
2662 ---------------------------------------------------------------------------*/
2664 /* Return true if T represents a stmt that always transfers control. */
2667 is_ctrl_stmt (tree t)
2669 return (TREE_CODE (t) == COND_EXPR
2670 || TREE_CODE (t) == SWITCH_EXPR
2671 || TREE_CODE (t) == GOTO_EXPR
2672 || TREE_CODE (t) == RETURN_EXPR
2673 || TREE_CODE (t) == RESX_EXPR);
2677 /* Return true if T is a statement that may alter the flow of control
2678 (e.g., a call to a non-returning function). */
2681 is_ctrl_altering_stmt (tree t)
2686 call = get_call_expr_in (t);
2689 /* A non-pure/const CALL_EXPR alters flow control if the current
2690 function has nonlocal labels. */
2691 if (TREE_SIDE_EFFECTS (call) && current_function_has_nonlocal_label)
2694 /* A CALL_EXPR also alters control flow if it does not return. */
2695 if (call_expr_flags (call) & ECF_NORETURN)
2699 /* If a statement can throw, it alters control flow. */
2700 return tree_can_throw_internal (t);
2704 /* Return true if T is a computed goto. */
2707 computed_goto_p (tree t)
2709 return (TREE_CODE (t) == GOTO_EXPR
2710 && TREE_CODE (GOTO_DESTINATION (t)) != LABEL_DECL);
2714 /* Checks whether EXPR is a simple local goto. */
2717 simple_goto_p (tree expr)
2719 return (TREE_CODE (expr) == GOTO_EXPR
2720 && TREE_CODE (GOTO_DESTINATION (expr)) == LABEL_DECL);
2724 /* Return true if T should start a new basic block. PREV_T is the
2725 statement preceding T. It is used when T is a label or a case label.
2726 Labels should only start a new basic block if their previous statement
2727 wasn't a label. Otherwise, sequence of labels would generate
2728 unnecessary basic blocks that only contain a single label. */
2731 stmt_starts_bb_p (tree t, tree prev_t)
2736 /* LABEL_EXPRs start a new basic block only if the preceding
2737 statement wasn't a label of the same type. This prevents the
2738 creation of consecutive blocks that have nothing but a single
2740 if (TREE_CODE (t) == LABEL_EXPR)
2742 /* Nonlocal and computed GOTO targets always start a new block. */
2743 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (t))
2744 || FORCED_LABEL (LABEL_EXPR_LABEL (t)))
2747 if (prev_t && TREE_CODE (prev_t) == LABEL_EXPR)
2749 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (prev_t)))
2752 cfg_stats.num_merged_labels++;
2763 /* Return true if T should end a basic block. */
2766 stmt_ends_bb_p (tree t)
2768 return is_ctrl_stmt (t) || is_ctrl_altering_stmt (t);
2772 /* Add gotos that used to be represented implicitly in the CFG. */
2775 disband_implicit_edges (void)
2778 block_stmt_iterator last;
2785 last = bsi_last (bb);
2786 stmt = last_stmt (bb);
2788 if (stmt && TREE_CODE (stmt) == COND_EXPR)
2790 /* Remove superfluous gotos from COND_EXPR branches. Moved
2791 from cfg_remove_useless_stmts here since it violates the
2792 invariants for tree--cfg correspondence and thus fits better
2793 here where we do it anyway. */
2794 e = find_edge (bb, bb->next_bb);
2797 if (e->flags & EDGE_TRUE_VALUE)
2798 COND_EXPR_THEN (stmt) = build_empty_stmt ();
2799 else if (e->flags & EDGE_FALSE_VALUE)
2800 COND_EXPR_ELSE (stmt) = build_empty_stmt ();
2803 e->flags |= EDGE_FALLTHRU;
2809 if (stmt && TREE_CODE (stmt) == RETURN_EXPR)
2811 /* Remove the RETURN_EXPR if we may fall though to the exit
2813 gcc_assert (EDGE_COUNT (bb->succs) == 1);
2814 gcc_assert (EDGE_SUCC (bb, 0)->dest == EXIT_BLOCK_PTR);
2816 if (bb->next_bb == EXIT_BLOCK_PTR
2817 && !TREE_OPERAND (stmt, 0))
2820 EDGE_SUCC (bb, 0)->flags |= EDGE_FALLTHRU;
2825 /* There can be no fallthru edge if the last statement is a control
2827 if (stmt && is_ctrl_stmt (stmt))
2830 /* Find a fallthru edge and emit the goto if necessary. */
2831 FOR_EACH_EDGE (e, ei, bb->succs)
2832 if (e->flags & EDGE_FALLTHRU)
2835 if (!e || e->dest == bb->next_bb)
2838 gcc_assert (e->dest != EXIT_BLOCK_PTR);
2839 label = tree_block_label (e->dest);
2841 stmt = build1 (GOTO_EXPR, void_type_node, label);
2842 #ifdef USE_MAPPED_LOCATION
2843 SET_EXPR_LOCATION (stmt, e->goto_locus);
2845 SET_EXPR_LOCUS (stmt, e->goto_locus);
2847 bsi_insert_after (&last, stmt, BSI_NEW_STMT);
2848 e->flags &= ~EDGE_FALLTHRU;
2852 /* Remove block annotations and other datastructures. */
2855 delete_tree_cfg_annotations (void)
2858 if (n_basic_blocks > 0)
2859 free_blocks_annotations ();
2861 label_to_block_map = NULL;
2868 /* Return the first statement in basic block BB. */
2871 first_stmt (basic_block bb)
2873 block_stmt_iterator i = bsi_start (bb);
2874 return !bsi_end_p (i) ? bsi_stmt (i) : NULL_TREE;
2878 /* Return the last statement in basic block BB. */
2881 last_stmt (basic_block bb)
2883 block_stmt_iterator b = bsi_last (bb);
2884 return !bsi_end_p (b) ? bsi_stmt (b) : NULL_TREE;
2888 /* Return a pointer to the last statement in block BB. */
2891 last_stmt_ptr (basic_block bb)
2893 block_stmt_iterator last = bsi_last (bb);
2894 return !bsi_end_p (last) ? bsi_stmt_ptr (last) : NULL;
2898 /* Return the last statement of an otherwise empty block. Return NULL
2899 if the block is totally empty, or if it contains more than one
2903 last_and_only_stmt (basic_block bb)
2905 block_stmt_iterator i = bsi_last (bb);
2911 last = bsi_stmt (i);
2916 /* Empty statements should no longer appear in the instruction stream.
2917 Everything that might have appeared before should be deleted by
2918 remove_useless_stmts, and the optimizers should just bsi_remove
2919 instead of smashing with build_empty_stmt.
2921 Thus the only thing that should appear here in a block containing
2922 one executable statement is a label. */
2923 prev = bsi_stmt (i);
2924 if (TREE_CODE (prev) == LABEL_EXPR)
2931 /* Mark BB as the basic block holding statement T. */
2934 set_bb_for_stmt (tree t, basic_block bb)
2936 if (TREE_CODE (t) == PHI_NODE)
2938 else if (TREE_CODE (t) == STATEMENT_LIST)
2940 tree_stmt_iterator i;
2941 for (i = tsi_start (t); !tsi_end_p (i); tsi_next (&i))
2942 set_bb_for_stmt (tsi_stmt (i), bb);
2946 stmt_ann_t ann = get_stmt_ann (t);
2949 /* If the statement is a label, add the label to block-to-labels map
2950 so that we can speed up edge creation for GOTO_EXPRs. */
2951 if (TREE_CODE (t) == LABEL_EXPR)
2955 t = LABEL_EXPR_LABEL (t);
2956 uid = LABEL_DECL_UID (t);
2959 LABEL_DECL_UID (t) = uid = cfun->last_label_uid++;
2960 if (VARRAY_SIZE (label_to_block_map) <= (unsigned) uid)
2961 VARRAY_GROW (label_to_block_map, 3 * uid / 2);
2964 /* We're moving an existing label. Make sure that we've
2965 removed it from the old block. */
2966 gcc_assert (!bb || !VARRAY_BB (label_to_block_map, uid));
2967 VARRAY_BB (label_to_block_map, uid) = bb;
2972 /* Finds iterator for STMT. */
2974 extern block_stmt_iterator
2975 bsi_for_stmt (tree stmt)
2977 block_stmt_iterator bsi;
2979 for (bsi = bsi_start (bb_for_stmt (stmt)); !bsi_end_p (bsi); bsi_next (&bsi))
2980 if (bsi_stmt (bsi) == stmt)
2986 /* Insert statement (or statement list) T before the statement
2987 pointed-to by iterator I. M specifies how to update iterator I
2988 after insertion (see enum bsi_iterator_update). */
2991 bsi_insert_before (block_stmt_iterator *i, tree t, enum bsi_iterator_update m)
2993 set_bb_for_stmt (t, i->bb);
2994 tsi_link_before (&i->tsi, t, m);
2999 /* Insert statement (or statement list) T after the statement
3000 pointed-to by iterator I. M specifies how to update iterator I
3001 after insertion (see enum bsi_iterator_update). */
3004 bsi_insert_after (block_stmt_iterator *i, tree t, enum bsi_iterator_update m)
3006 set_bb_for_stmt (t, i->bb);
3007 tsi_link_after (&i->tsi, t, m);
3012 /* Remove the statement pointed to by iterator I. The iterator is updated
3013 to the next statement. */
3016 bsi_remove (block_stmt_iterator *i)
3018 tree t = bsi_stmt (*i);
3019 set_bb_for_stmt (t, NULL);
3020 tsi_delink (&i->tsi);
3024 /* Move the statement at FROM so it comes right after the statement at TO. */
3027 bsi_move_after (block_stmt_iterator *from, block_stmt_iterator *to)
3029 tree stmt = bsi_stmt (*from);
3031 bsi_insert_after (to, stmt, BSI_SAME_STMT);
3035 /* Move the statement at FROM so it comes right before the statement at TO. */
3038 bsi_move_before (block_stmt_iterator *from, block_stmt_iterator *to)
3040 tree stmt = bsi_stmt (*from);
3042 bsi_insert_before (to, stmt, BSI_SAME_STMT);
3046 /* Move the statement at FROM to the end of basic block BB. */
3049 bsi_move_to_bb_end (block_stmt_iterator *from, basic_block bb)
3051 block_stmt_iterator last = bsi_last (bb);
3053 /* Have to check bsi_end_p because it could be an empty block. */
3054 if (!bsi_end_p (last) && is_ctrl_stmt (bsi_stmt (last)))
3055 bsi_move_before (from, &last);
3057 bsi_move_after (from, &last);
3061 /* Replace the contents of the statement pointed to by iterator BSI
3062 with STMT. If PRESERVE_EH_INFO is true, the exception handling
3063 information of the original statement is preserved. */
3066 bsi_replace (const block_stmt_iterator *bsi, tree stmt, bool preserve_eh_info)
3069 tree orig_stmt = bsi_stmt (*bsi);
3071 SET_EXPR_LOCUS (stmt, EXPR_LOCUS (orig_stmt));
3072 set_bb_for_stmt (stmt, bsi->bb);
3074 /* Preserve EH region information from the original statement, if
3075 requested by the caller. */
3076 if (preserve_eh_info)
3078 eh_region = lookup_stmt_eh_region (orig_stmt);
3080 add_stmt_to_eh_region (stmt, eh_region);
3083 *bsi_stmt_ptr (*bsi) = stmt;
3088 /* Insert the statement pointed-to by BSI into edge E. Every attempt
3089 is made to place the statement in an existing basic block, but
3090 sometimes that isn't possible. When it isn't possible, the edge is
3091 split and the statement is added to the new block.
3093 In all cases, the returned *BSI points to the correct location. The
3094 return value is true if insertion should be done after the location,
3095 or false if it should be done before the location. If new basic block
3096 has to be created, it is stored in *NEW_BB. */
3099 tree_find_edge_insert_loc (edge e, block_stmt_iterator *bsi,
3100 basic_block *new_bb)
3102 basic_block dest, src;
3108 /* If the destination has one predecessor which has no PHI nodes,
3109 insert there. Except for the exit block.
3111 The requirement for no PHI nodes could be relaxed. Basically we
3112 would have to examine the PHIs to prove that none of them used
3113 the value set by the statement we want to insert on E. That
3114 hardly seems worth the effort. */
3115 if (EDGE_COUNT (dest->preds) == 1
3116 && ! phi_nodes (dest)
3117 && dest != EXIT_BLOCK_PTR)
3119 *bsi = bsi_start (dest);
3120 if (bsi_end_p (*bsi))
3123 /* Make sure we insert after any leading labels. */
3124 tmp = bsi_stmt (*bsi);
3125 while (TREE_CODE (tmp) == LABEL_EXPR)
3128 if (bsi_end_p (*bsi))
3130 tmp = bsi_stmt (*bsi);
3133 if (bsi_end_p (*bsi))
3135 *bsi = bsi_last (dest);
3142 /* If the source has one successor, the edge is not abnormal and
3143 the last statement does not end a basic block, insert there.
3144 Except for the entry block. */
3146 if ((e->flags & EDGE_ABNORMAL) == 0
3147 && EDGE_COUNT (src->succs) == 1
3148 && src != ENTRY_BLOCK_PTR)
3150 *bsi = bsi_last (src);
3151 if (bsi_end_p (*bsi))
3154 tmp = bsi_stmt (*bsi);
3155 if (!stmt_ends_bb_p (tmp))
3158 /* Insert code just before returning the value. We may need to decompose
3159 the return in the case it contains non-trivial operand. */
3160 if (TREE_CODE (tmp) == RETURN_EXPR)
3162 tree op = TREE_OPERAND (tmp, 0);
3163 if (!is_gimple_val (op))
3165 gcc_assert (TREE_CODE (op) == MODIFY_EXPR);
3166 bsi_insert_before (bsi, op, BSI_NEW_STMT);
3167 TREE_OPERAND (tmp, 0) = TREE_OPERAND (op, 0);
3174 /* Otherwise, create a new basic block, and split this edge. */
3175 dest = split_edge (e);
3178 e = EDGE_PRED (dest, 0);
3183 /* This routine will commit all pending edge insertions, creating any new
3184 basic blocks which are necessary. */
3187 bsi_commit_edge_inserts (void)
3193 bsi_commit_one_edge_insert (EDGE_SUCC (ENTRY_BLOCK_PTR, 0), NULL);
3196 FOR_EACH_EDGE (e, ei, bb->succs)
3197 bsi_commit_one_edge_insert (e, NULL);
3201 /* Commit insertions pending at edge E. If a new block is created, set NEW_BB
3202 to this block, otherwise set it to NULL. */
3205 bsi_commit_one_edge_insert (edge e, basic_block *new_bb)
3209 if (PENDING_STMT (e))
3211 block_stmt_iterator bsi;
3212 tree stmt = PENDING_STMT (e);
3214 PENDING_STMT (e) = NULL_TREE;
3216 if (tree_find_edge_insert_loc (e, &bsi, new_bb))
3217 bsi_insert_after (&bsi, stmt, BSI_NEW_STMT);
3219 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
3224 /* Add STMT to the pending list of edge E. No actual insertion is
3225 made until a call to bsi_commit_edge_inserts () is made. */
3228 bsi_insert_on_edge (edge e, tree stmt)
3230 append_to_statement_list (stmt, &PENDING_STMT (e));
3233 /* Similar to bsi_insert_on_edge+bsi_commit_edge_inserts. If a new
3234 block has to be created, it is returned. */
3237 bsi_insert_on_edge_immediate (edge e, tree stmt)
3239 block_stmt_iterator bsi;
3240 basic_block new_bb = NULL;
3242 gcc_assert (!PENDING_STMT (e));
3244 if (tree_find_edge_insert_loc (e, &bsi, &new_bb))
3245 bsi_insert_after (&bsi, stmt, BSI_NEW_STMT);
3247 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
3252 /*---------------------------------------------------------------------------
3253 Tree specific functions for CFG manipulation
3254 ---------------------------------------------------------------------------*/
3256 /* Reinstall those PHI arguments queued in OLD_EDGE to NEW_EDGE. */
3259 reinstall_phi_args (edge new_edge, edge old_edge)
3263 if (!PENDING_STMT (old_edge))
3266 for (var = PENDING_STMT (old_edge), phi = phi_nodes (new_edge->dest);
3268 var = TREE_CHAIN (var), phi = PHI_CHAIN (phi))
3270 tree result = TREE_PURPOSE (var);
3271 tree arg = TREE_VALUE (var);
3273 gcc_assert (result == PHI_RESULT (phi));
3275 add_phi_arg (phi, arg, new_edge);
3278 PENDING_STMT (old_edge) = NULL;
3281 /* Split a (typically critical) edge EDGE_IN. Return the new block.
3282 Abort on abnormal edges. */
3285 tree_split_edge (edge edge_in)
3287 basic_block new_bb, after_bb, dest, src;
3290 /* Abnormal edges cannot be split. */
3291 gcc_assert (!(edge_in->flags & EDGE_ABNORMAL));
3294 dest = edge_in->dest;
3296 /* Place the new block in the block list. Try to keep the new block
3297 near its "logical" location. This is of most help to humans looking
3298 at debugging dumps. */
3299 if (dest->prev_bb && find_edge (dest->prev_bb, dest))
3300 after_bb = edge_in->src;
3302 after_bb = dest->prev_bb;
3304 new_bb = create_empty_bb (after_bb);
3305 new_bb->frequency = EDGE_FREQUENCY (edge_in);
3306 new_bb->count = edge_in->count;
3307 new_edge = make_edge (new_bb, dest, EDGE_FALLTHRU);
3308 new_edge->probability = REG_BR_PROB_BASE;
3309 new_edge->count = edge_in->count;
3311 e = redirect_edge_and_branch (edge_in, new_bb);
3313 reinstall_phi_args (new_edge, e);
3319 /* Return true when BB has label LABEL in it. */
3322 has_label_p (basic_block bb, tree label)
3324 block_stmt_iterator bsi;
3326 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3328 tree stmt = bsi_stmt (bsi);
3330 if (TREE_CODE (stmt) != LABEL_EXPR)
3332 if (LABEL_EXPR_LABEL (stmt) == label)
3339 /* Callback for walk_tree, check that all elements with address taken are
3340 properly noticed as such. The DATA is an int* that is 1 if TP was seen
3341 inside a PHI node. */
3344 verify_expr (tree *tp, int *walk_subtrees, void *data ATTRIBUTE_UNUSED)
3347 bool in_phi = (data != NULL);
3352 /* Check operand N for being valid GIMPLE and give error MSG if not.
3353 We check for constants explicitly since they are not considered
3354 gimple invariants if they overflowed. */
3355 #define CHECK_OP(N, MSG) \
3356 do { if (!CONSTANT_CLASS_P (TREE_OPERAND (t, N)) \
3357 && !is_gimple_val (TREE_OPERAND (t, N))) \
3358 { error (MSG); return TREE_OPERAND (t, N); }} while (0)
3360 switch (TREE_CODE (t))
3363 if (SSA_NAME_IN_FREE_LIST (t))
3365 error ("SSA name in freelist but still referenced");
3371 x = TREE_OPERAND (t, 0);
3372 if (TREE_CODE (x) == BIT_FIELD_REF
3373 && is_gimple_reg (TREE_OPERAND (x, 0)))
3375 error ("GIMPLE register modified with BIT_FIELD_REF");
3381 /* ??? tree-ssa-alias.c may have overlooked dead PHI nodes, missing
3382 dead PHIs that take the address of something. But if the PHI
3383 result is dead, the fact that it takes the address of anything
3384 is irrelevant. Because we can not tell from here if a PHI result
3385 is dead, we just skip this check for PHIs altogether. This means
3386 we may be missing "valid" checks, but what can you do?
3387 This was PR19217. */
3391 /* Skip any references (they will be checked when we recurse down the
3392 tree) and ensure that any variable used as a prefix is marked
3394 for (x = TREE_OPERAND (t, 0);
3395 handled_component_p (x);
3396 x = TREE_OPERAND (x, 0))
3399 if (TREE_CODE (x) != VAR_DECL && TREE_CODE (x) != PARM_DECL)
3401 if (!TREE_ADDRESSABLE (x))
3403 error ("address taken, but ADDRESSABLE bit not set");
3409 x = COND_EXPR_COND (t);
3410 if (TREE_CODE (TREE_TYPE (x)) != BOOLEAN_TYPE)
3412 error ("non-boolean used in condition");
3419 case FIX_TRUNC_EXPR:
3421 case FIX_FLOOR_EXPR:
3422 case FIX_ROUND_EXPR:
3427 case NON_LVALUE_EXPR:
3428 case TRUTH_NOT_EXPR:
3429 CHECK_OP (0, "Invalid operand to unary operator");
3436 case ARRAY_RANGE_REF:
3438 case VIEW_CONVERT_EXPR:
3439 /* We have a nest of references. Verify that each of the operands
3440 that determine where to reference is either a constant or a variable,
3441 verify that the base is valid, and then show we've already checked
3443 while (handled_component_p (t))
3445 if (TREE_CODE (t) == COMPONENT_REF && TREE_OPERAND (t, 2))
3446 CHECK_OP (2, "Invalid COMPONENT_REF offset operator");
3447 else if (TREE_CODE (t) == ARRAY_REF
3448 || TREE_CODE (t) == ARRAY_RANGE_REF)
3450 CHECK_OP (1, "Invalid array index.");
3451 if (TREE_OPERAND (t, 2))
3452 CHECK_OP (2, "Invalid array lower bound.");
3453 if (TREE_OPERAND (t, 3))
3454 CHECK_OP (3, "Invalid array stride.");
3456 else if (TREE_CODE (t) == BIT_FIELD_REF)
3458 CHECK_OP (1, "Invalid operand to BIT_FIELD_REF");
3459 CHECK_OP (2, "Invalid operand to BIT_FIELD_REF");
3462 t = TREE_OPERAND (t, 0);
3465 if (!CONSTANT_CLASS_P (t) && !is_gimple_lvalue (t))
3467 error ("Invalid reference prefix.");
3479 case UNORDERED_EXPR:
3490 case TRUNC_DIV_EXPR:
3492 case FLOOR_DIV_EXPR:
3493 case ROUND_DIV_EXPR:
3494 case TRUNC_MOD_EXPR:
3496 case FLOOR_MOD_EXPR:
3497 case ROUND_MOD_EXPR:
3499 case EXACT_DIV_EXPR:
3509 CHECK_OP (0, "Invalid operand to binary operator");
3510 CHECK_OP (1, "Invalid operand to binary operator");
3522 /* Verify STMT, return true if STMT is not in GIMPLE form.
3523 TODO: Implement type checking. */
3526 verify_stmt (tree stmt, bool last_in_block)
3530 if (!is_gimple_stmt (stmt))
3532 error ("Is not a valid GIMPLE statement.");
3536 addr = walk_tree (&stmt, verify_expr, NULL, NULL);
3539 debug_generic_stmt (addr);
3543 /* If the statement is marked as part of an EH region, then it is
3544 expected that the statement could throw. Verify that when we
3545 have optimizations that simplify statements such that we prove
3546 that they cannot throw, that we update other data structures
3548 if (lookup_stmt_eh_region (stmt) >= 0)
3550 if (!tree_could_throw_p (stmt))
3552 error ("Statement marked for throw, but doesn%'t.");
3555 if (!last_in_block && tree_can_throw_internal (stmt))
3557 error ("Statement marked for throw in middle of block.");
3565 debug_generic_stmt (stmt);
3570 /* Return true when the T can be shared. */
3573 tree_node_can_be_shared (tree t)
3575 if (IS_TYPE_OR_DECL_P (t)
3576 /* We check for constants explicitly since they are not considered
3577 gimple invariants if they overflowed. */
3578 || CONSTANT_CLASS_P (t)
3579 || is_gimple_min_invariant (t)
3580 || TREE_CODE (t) == SSA_NAME
3581 || t == error_mark_node)
3584 if (TREE_CODE (t) == CASE_LABEL_EXPR)
3587 while (((TREE_CODE (t) == ARRAY_REF || TREE_CODE (t) == ARRAY_RANGE_REF)
3588 /* We check for constants explicitly since they are not considered
3589 gimple invariants if they overflowed. */
3590 && (CONSTANT_CLASS_P (TREE_OPERAND (t, 1))
3591 || is_gimple_min_invariant (TREE_OPERAND (t, 1))))
3592 || (TREE_CODE (t) == COMPONENT_REF
3593 || TREE_CODE (t) == REALPART_EXPR
3594 || TREE_CODE (t) == IMAGPART_EXPR))
3595 t = TREE_OPERAND (t, 0);
3604 /* Called via walk_trees. Verify tree sharing. */
3607 verify_node_sharing (tree * tp, int *walk_subtrees, void *data)
3609 htab_t htab = (htab_t) data;
3612 if (tree_node_can_be_shared (*tp))
3614 *walk_subtrees = false;
3618 slot = htab_find_slot (htab, *tp, INSERT);
3627 /* Verify the GIMPLE statement chain. */
3633 block_stmt_iterator bsi;
3638 timevar_push (TV_TREE_STMT_VERIFY);
3639 htab = htab_create (37, htab_hash_pointer, htab_eq_pointer, NULL);
3646 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
3648 int phi_num_args = PHI_NUM_ARGS (phi);
3650 for (i = 0; i < phi_num_args; i++)
3652 tree t = PHI_ARG_DEF (phi, i);
3655 /* Addressable variables do have SSA_NAMEs but they
3656 are not considered gimple values. */
3657 if (TREE_CODE (t) != SSA_NAME
3658 && TREE_CODE (t) != FUNCTION_DECL
3659 && !is_gimple_val (t))
3661 error ("PHI def is not a GIMPLE value");
3662 debug_generic_stmt (phi);
3663 debug_generic_stmt (t);
3667 addr = walk_tree (&t, verify_expr, (void *) 1, NULL);
3670 debug_generic_stmt (addr);
3674 addr = walk_tree (&t, verify_node_sharing, htab, NULL);
3677 error ("Incorrect sharing of tree nodes");
3678 debug_generic_stmt (phi);
3679 debug_generic_stmt (addr);
3685 for (bsi = bsi_start (bb); !bsi_end_p (bsi); )
3687 tree stmt = bsi_stmt (bsi);
3689 err |= verify_stmt (stmt, bsi_end_p (bsi));
3690 addr = walk_tree (&stmt, verify_node_sharing, htab, NULL);
3693 error ("Incorrect sharing of tree nodes");
3694 debug_generic_stmt (stmt);
3695 debug_generic_stmt (addr);
3702 internal_error ("verify_stmts failed.");
3705 timevar_pop (TV_TREE_STMT_VERIFY);
3709 /* Verifies that the flow information is OK. */
3712 tree_verify_flow_info (void)
3716 block_stmt_iterator bsi;
3721 if (ENTRY_BLOCK_PTR->stmt_list)
3723 error ("ENTRY_BLOCK has a statement list associated with it\n");
3727 if (EXIT_BLOCK_PTR->stmt_list)
3729 error ("EXIT_BLOCK has a statement list associated with it\n");
3733 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
3734 if (e->flags & EDGE_FALLTHRU)
3736 error ("Fallthru to exit from bb %d\n", e->src->index);
3742 bool found_ctrl_stmt = false;
3746 /* Skip labels on the start of basic block. */
3747 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3749 tree prev_stmt = stmt;
3751 stmt = bsi_stmt (bsi);
3753 if (TREE_CODE (stmt) != LABEL_EXPR)
3756 if (prev_stmt && DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)))
3758 error ("Nonlocal label %s is not first "
3759 "in a sequence of labels in bb %d",
3760 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt))),
3765 if (label_to_block (LABEL_EXPR_LABEL (stmt)) != bb)
3767 error ("Label %s to block does not match in bb %d\n",
3768 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt))),
3773 if (decl_function_context (LABEL_EXPR_LABEL (stmt))
3774 != current_function_decl)
3776 error ("Label %s has incorrect context in bb %d\n",
3777 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt))),
3783 /* Verify that body of basic block BB is free of control flow. */
3784 for (; !bsi_end_p (bsi); bsi_next (&bsi))
3786 tree stmt = bsi_stmt (bsi);
3788 if (found_ctrl_stmt)
3790 error ("Control flow in the middle of basic block %d\n",
3795 if (stmt_ends_bb_p (stmt))
3796 found_ctrl_stmt = true;
3798 if (TREE_CODE (stmt) == LABEL_EXPR)
3800 error ("Label %s in the middle of basic block %d\n",
3801 IDENTIFIER_POINTER (DECL_NAME (stmt)),
3806 bsi = bsi_last (bb);
3807 if (bsi_end_p (bsi))
3810 stmt = bsi_stmt (bsi);
3812 if (is_ctrl_stmt (stmt))
3814 FOR_EACH_EDGE (e, ei, bb->succs)
3815 if (e->flags & EDGE_FALLTHRU)
3817 error ("Fallthru edge after a control statement in bb %d \n",
3823 switch (TREE_CODE (stmt))
3829 if (TREE_CODE (COND_EXPR_THEN (stmt)) != GOTO_EXPR
3830 || TREE_CODE (COND_EXPR_ELSE (stmt)) != GOTO_EXPR)
3832 error ("Structured COND_EXPR at the end of bb %d\n", bb->index);
3836 extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
3838 if (!true_edge || !false_edge
3839 || !(true_edge->flags & EDGE_TRUE_VALUE)
3840 || !(false_edge->flags & EDGE_FALSE_VALUE)
3841 || (true_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL))
3842 || (false_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL))
3843 || EDGE_COUNT (bb->succs) >= 3)
3845 error ("Wrong outgoing edge flags at end of bb %d\n",
3850 if (!has_label_p (true_edge->dest,
3851 GOTO_DESTINATION (COND_EXPR_THEN (stmt))))
3853 error ("%<then%> label does not match edge at end of bb %d\n",
3858 if (!has_label_p (false_edge->dest,
3859 GOTO_DESTINATION (COND_EXPR_ELSE (stmt))))
3861 error ("%<else%> label does not match edge at end of bb %d\n",
3869 if (simple_goto_p (stmt))
3871 error ("Explicit goto at end of bb %d\n", bb->index);
3876 /* FIXME. We should double check that the labels in the
3877 destination blocks have their address taken. */
3878 FOR_EACH_EDGE (e, ei, bb->succs)
3879 if ((e->flags & (EDGE_FALLTHRU | EDGE_TRUE_VALUE
3880 | EDGE_FALSE_VALUE))
3881 || !(e->flags & EDGE_ABNORMAL))
3883 error ("Wrong outgoing edge flags at end of bb %d\n",
3891 if (EDGE_COUNT (bb->succs) != 1
3892 || (EDGE_SUCC (bb, 0)->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL
3893 | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
3895 error ("Wrong outgoing edge flags at end of bb %d\n", bb->index);
3898 if (EDGE_SUCC (bb, 0)->dest != EXIT_BLOCK_PTR)
3900 error ("Return edge does not point to exit in bb %d\n",
3913 vec = SWITCH_LABELS (stmt);
3914 n = TREE_VEC_LENGTH (vec);
3916 /* Mark all the destination basic blocks. */
3917 for (i = 0; i < n; ++i)
3919 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
3920 basic_block label_bb = label_to_block (lab);
3922 gcc_assert (!label_bb->aux || label_bb->aux == (void *)1);
3923 label_bb->aux = (void *)1;
3926 /* Verify that the case labels are sorted. */
3927 prev = TREE_VEC_ELT (vec, 0);
3928 for (i = 1; i < n - 1; ++i)
3930 tree c = TREE_VEC_ELT (vec, i);
3933 error ("Found default case not at end of case vector");
3937 if (! tree_int_cst_lt (CASE_LOW (prev), CASE_LOW (c)))
3939 error ("Case labels not sorted:\n ");
3940 print_generic_expr (stderr, prev, 0);
3941 fprintf (stderr," is greater than ");
3942 print_generic_expr (stderr, c, 0);
3943 fprintf (stderr," but comes before it.\n");
3948 if (CASE_LOW (TREE_VEC_ELT (vec, n - 1)))
3950 error ("No default case found at end of case vector");
3954 FOR_EACH_EDGE (e, ei, bb->succs)
3958 error ("Extra outgoing edge %d->%d\n",
3959 bb->index, e->dest->index);
3962 e->dest->aux = (void *)2;
3963 if ((e->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL
3964 | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
3966 error ("Wrong outgoing edge flags at end of bb %d\n",
3972 /* Check that we have all of them. */
3973 for (i = 0; i < n; ++i)
3975 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
3976 basic_block label_bb = label_to_block (lab);
3978 if (label_bb->aux != (void *)2)
3980 error ("Missing edge %i->%i",
3981 bb->index, label_bb->index);
3986 FOR_EACH_EDGE (e, ei, bb->succs)
3987 e->dest->aux = (void *)0;
3994 if (dom_computed[CDI_DOMINATORS] >= DOM_NO_FAST_QUERY)
3995 verify_dominators (CDI_DOMINATORS);
4001 /* Updates phi nodes after creating a forwarder block joined
4002 by edge FALLTHRU. */
4005 tree_make_forwarder_block (edge fallthru)
4009 basic_block dummy, bb;
4010 tree phi, new_phi, var;
4012 dummy = fallthru->src;
4013 bb = fallthru->dest;
4015 if (EDGE_COUNT (bb->preds) == 1)
4018 /* If we redirected a branch we must create new phi nodes at the
4020 for (phi = phi_nodes (dummy); phi; phi = PHI_CHAIN (phi))
4022 var = PHI_RESULT (phi);
4023 new_phi = create_phi_node (var, bb);
4024 SSA_NAME_DEF_STMT (var) = new_phi;
4025 SET_PHI_RESULT (phi, make_ssa_name (SSA_NAME_VAR (var), phi));
4026 add_phi_arg (new_phi, PHI_RESULT (phi), fallthru);
4029 /* Ensure that the PHI node chain is in the same order. */
4030 set_phi_nodes (bb, phi_reverse (phi_nodes (bb)));
4032 /* Add the arguments we have stored on edges. */
4033 FOR_EACH_EDGE (e, ei, bb->preds)
4038 flush_pending_stmts (e);
4043 /* Return true if basic block BB does nothing except pass control
4044 flow to another block and that we can safely insert a label at
4045 the start of the successor block.
4047 As a precondition, we require that BB be not equal to
4051 tree_forwarder_block_p (basic_block bb, bool phi_wanted)
4053 block_stmt_iterator bsi;
4055 /* BB must have a single outgoing edge. */
4056 if (EDGE_COUNT (bb->succs) != 1
4057 /* If PHI_WANTED is false, BB must not have any PHI nodes.
4058 Otherwise, BB must have PHI nodes. */
4059 || (phi_nodes (bb) != NULL_TREE) != phi_wanted
4060 /* BB may not be a predecessor of EXIT_BLOCK_PTR. */
4061 || EDGE_SUCC (bb, 0)->dest == EXIT_BLOCK_PTR
4062 /* Nor should this be an infinite loop. */
4063 || EDGE_SUCC (bb, 0)->dest == bb
4064 /* BB may not have an abnormal outgoing edge. */
4065 || (EDGE_SUCC (bb, 0)->flags & EDGE_ABNORMAL))
4069 gcc_assert (bb != ENTRY_BLOCK_PTR);
4072 /* Now walk through the statements backward. We can ignore labels,
4073 anything else means this is not a forwarder block. */
4074 for (bsi = bsi_last (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4076 tree stmt = bsi_stmt (bsi);
4078 switch (TREE_CODE (stmt))
4081 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)))
4090 if (find_edge (ENTRY_BLOCK_PTR, bb))
4096 /* Return true if BB has at least one abnormal incoming edge. */
4099 has_abnormal_incoming_edge_p (basic_block bb)
4104 FOR_EACH_EDGE (e, ei, bb->preds)
4105 if (e->flags & EDGE_ABNORMAL)
4111 /* Removes forwarder block BB. Returns false if this failed. If a new
4112 forwarder block is created due to redirection of edges, it is
4113 stored to worklist. */
4116 remove_forwarder_block (basic_block bb, basic_block **worklist)
4118 edge succ = EDGE_SUCC (bb, 0), e, s;
4119 basic_block dest = succ->dest;
4123 block_stmt_iterator bsi, bsi_to;
4124 bool seen_abnormal_edge = false;
4126 /* We check for infinite loops already in tree_forwarder_block_p.
4127 However it may happen that the infinite loop is created
4128 afterwards due to removal of forwarders. */
4132 /* If the destination block consists of a nonlocal label, do not merge
4134 label = first_stmt (dest);
4136 && TREE_CODE (label) == LABEL_EXPR
4137 && DECL_NONLOCAL (LABEL_EXPR_LABEL (label)))
4140 /* If there is an abnormal edge to basic block BB, but not into
4141 dest, problems might occur during removal of the phi node at out
4142 of ssa due to overlapping live ranges of registers.
4144 If there is an abnormal edge in DEST, the problems would occur
4145 anyway since cleanup_dead_labels would then merge the labels for
4146 two different eh regions, and rest of exception handling code
4149 So if there is an abnormal edge to BB, proceed only if there is
4150 no abnormal edge to DEST and there are no phi nodes in DEST. */
4151 if (has_abnormal_incoming_edge_p (bb))
4153 seen_abnormal_edge = true;
4155 if (has_abnormal_incoming_edge_p (dest)
4156 || phi_nodes (dest) != NULL_TREE)
4160 /* If there are phi nodes in DEST, and some of the blocks that are
4161 predecessors of BB are also predecessors of DEST, check that the
4162 phi node arguments match. */
4163 if (phi_nodes (dest))
4165 FOR_EACH_EDGE (e, ei, bb->preds)
4167 s = find_edge (e->src, dest);
4171 if (!phi_alternatives_equal (dest, succ, s))
4176 /* Redirect the edges. */
4177 for (ei = ei_start (bb->preds); (e = ei_safe_edge (ei)); )
4179 if (e->flags & EDGE_ABNORMAL)
4181 /* If there is an abnormal edge, redirect it anyway, and
4182 move the labels to the new block to make it legal. */
4183 s = redirect_edge_succ_nodup (e, dest);
4186 s = redirect_edge_and_branch (e, dest);
4190 /* Create arguments for the phi nodes, since the edge was not
4192 for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi))
4193 add_phi_arg (phi, PHI_ARG_DEF (phi, succ->dest_idx), s);
4197 /* The source basic block might become a forwarder. We know
4198 that it was not a forwarder before, since it used to have
4199 at least two outgoing edges, so we may just add it to
4201 if (tree_forwarder_block_p (s->src, false))
4202 *(*worklist)++ = s->src;
4206 if (seen_abnormal_edge)
4208 /* Move the labels to the new block, so that the redirection of
4209 the abnormal edges works. */
4211 bsi_to = bsi_start (dest);
4212 for (bsi = bsi_start (bb); !bsi_end_p (bsi); )
4214 label = bsi_stmt (bsi);
4215 gcc_assert (TREE_CODE (label) == LABEL_EXPR);
4217 bsi_insert_before (&bsi_to, label, BSI_CONTINUE_LINKING);
4221 /* Update the dominators. */
4222 if (dom_info_available_p (CDI_DOMINATORS))
4224 basic_block dom, dombb, domdest;
4226 dombb = get_immediate_dominator (CDI_DOMINATORS, bb);
4227 domdest = get_immediate_dominator (CDI_DOMINATORS, dest);
4230 /* Shortcut to avoid calling (relatively expensive)
4231 nearest_common_dominator unless necessary. */
4235 dom = nearest_common_dominator (CDI_DOMINATORS, domdest, dombb);
4237 set_immediate_dominator (CDI_DOMINATORS, dest, dom);
4240 /* And kill the forwarder block. */
4241 delete_basic_block (bb);
4246 /* Removes forwarder blocks. */
4249 cleanup_forwarder_blocks (void)
4252 bool changed = false;
4253 basic_block *worklist = xmalloc (sizeof (basic_block) * n_basic_blocks);
4254 basic_block *current = worklist;
4258 if (tree_forwarder_block_p (bb, false))
4262 while (current != worklist)
4265 changed |= remove_forwarder_block (bb, ¤t);
4272 /* Merge the PHI nodes at BB into those at BB's sole successor. */
4275 remove_forwarder_block_with_phi (basic_block bb)
4277 edge succ = EDGE_SUCC (bb, 0);
4278 basic_block dest = succ->dest;
4280 basic_block dombb, domdest, dom;
4282 /* We check for infinite loops already in tree_forwarder_block_p.
4283 However it may happen that the infinite loop is created
4284 afterwards due to removal of forwarders. */
4288 /* If the destination block consists of a nonlocal label, do not
4290 label = first_stmt (dest);
4292 && TREE_CODE (label) == LABEL_EXPR
4293 && DECL_NONLOCAL (LABEL_EXPR_LABEL (label)))
4296 /* Redirect each incoming edge to BB to DEST. */
4297 while (EDGE_COUNT (bb->preds) > 0)
4299 edge e = EDGE_PRED (bb, 0), s;
4302 s = find_edge (e->src, dest);
4305 /* We already have an edge S from E->src to DEST. If S and
4306 E->dest's sole successor edge have the same PHI arguments
4307 at DEST, redirect S to DEST. */
4308 if (phi_alternatives_equal (dest, s, succ))
4310 e = redirect_edge_and_branch (e, dest);
4311 PENDING_STMT (e) = NULL_TREE;
4315 /* PHI arguments are different. Create a forwarder block by
4316 splitting E so that we can merge PHI arguments on E to
4318 e = EDGE_SUCC (split_edge (e), 0);
4321 s = redirect_edge_and_branch (e, dest);
4323 /* redirect_edge_and_branch must not create a new edge. */
4324 gcc_assert (s == e);
4326 /* Add to the PHI nodes at DEST each PHI argument removed at the
4327 destination of E. */
4328 for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi))
4330 tree def = PHI_ARG_DEF (phi, succ->dest_idx);
4332 if (TREE_CODE (def) == SSA_NAME)
4336 /* If DEF is one of the results of PHI nodes removed during
4337 redirection, replace it with the PHI argument that used
4339 for (var = PENDING_STMT (e); var; var = TREE_CHAIN (var))
4341 tree old_arg = TREE_PURPOSE (var);
4342 tree new_arg = TREE_VALUE (var);
4352 add_phi_arg (phi, def, s);
4355 PENDING_STMT (e) = NULL;
4358 /* Update the dominators. */
4359 dombb = get_immediate_dominator (CDI_DOMINATORS, bb);
4360 domdest = get_immediate_dominator (CDI_DOMINATORS, dest);
4363 /* Shortcut to avoid calling (relatively expensive)
4364 nearest_common_dominator unless necessary. */
4368 dom = nearest_common_dominator (CDI_DOMINATORS, domdest, dombb);
4370 set_immediate_dominator (CDI_DOMINATORS, dest, dom);
4372 /* Remove BB since all of BB's incoming edges have been redirected
4374 delete_basic_block (bb);
4377 /* This pass merges PHI nodes if one feeds into another. For example,
4378 suppose we have the following:
4385 # tem_6 = PHI <tem_17(8), tem_23(7)>;
4388 # tem_3 = PHI <tem_6(9), tem_2(5)>;
4391 Then we merge the first PHI node into the second one like so:
4393 goto <bb 9> (<L10>);
4398 # tem_3 = PHI <tem_23(7), tem_2(5), tem_17(8)>;
4403 merge_phi_nodes (void)
4405 basic_block *worklist = xmalloc (sizeof (basic_block) * n_basic_blocks);
4406 basic_block *current = worklist;
4409 calculate_dominance_info (CDI_DOMINATORS);
4411 /* Find all PHI nodes that we may be able to merge. */
4416 /* Look for a forwarder block with PHI nodes. */
4417 if (!tree_forwarder_block_p (bb, true))
4420 dest = EDGE_SUCC (bb, 0)->dest;
4422 /* We have to feed into another basic block with PHI
4424 if (!phi_nodes (dest)
4425 /* We don't want to deal with a basic block with
4427 || has_abnormal_incoming_edge_p (bb))
4430 if (!dominated_by_p (CDI_DOMINATORS, dest, bb))
4432 /* If BB does not dominate DEST, then the PHI nodes at
4433 DEST must be the only users of the results of the PHI
4439 /* Now let's drain WORKLIST. */
4440 while (current != worklist)
4443 remove_forwarder_block_with_phi (bb);
4450 gate_merge_phi (void)
4455 struct tree_opt_pass pass_merge_phi = {
4456 "mergephi", /* name */
4457 gate_merge_phi, /* gate */
4458 merge_phi_nodes, /* execute */
4461 0, /* static_pass_number */
4462 TV_TREE_MERGE_PHI, /* tv_id */
4463 PROP_cfg | PROP_ssa, /* properties_required */
4464 0, /* properties_provided */
4465 0, /* properties_destroyed */
4466 0, /* todo_flags_start */
4467 TODO_dump_func | TODO_ggc_collect /* todo_flags_finish */
4472 /* Return a non-special label in the head of basic block BLOCK.
4473 Create one if it doesn't exist. */
4476 tree_block_label (basic_block bb)
4478 block_stmt_iterator i, s = bsi_start (bb);
4482 for (i = s; !bsi_end_p (i); first = false, bsi_next (&i))
4484 stmt = bsi_stmt (i);
4485 if (TREE_CODE (stmt) != LABEL_EXPR)
4487 label = LABEL_EXPR_LABEL (stmt);
4488 if (!DECL_NONLOCAL (label))
4491 bsi_move_before (&i, &s);
4496 label = create_artificial_label ();
4497 stmt = build1 (LABEL_EXPR, void_type_node, label);
4498 bsi_insert_before (&s, stmt, BSI_NEW_STMT);
4503 /* Attempt to perform edge redirection by replacing a possibly complex
4504 jump instruction by a goto or by removing the jump completely.
4505 This can apply only if all edges now point to the same block. The
4506 parameters and return values are equivalent to
4507 redirect_edge_and_branch. */
4510 tree_try_redirect_by_replacing_jump (edge e, basic_block target)
4512 basic_block src = e->src;
4513 block_stmt_iterator b;
4516 /* We can replace or remove a complex jump only when we have exactly
4518 if (EDGE_COUNT (src->succs) != 2
4519 /* Verify that all targets will be TARGET. Specifically, the
4520 edge that is not E must also go to TARGET. */
4521 || EDGE_SUCC (src, EDGE_SUCC (src, 0) == e)->dest != target)
4527 stmt = bsi_stmt (b);
4529 if (TREE_CODE (stmt) == COND_EXPR
4530 || TREE_CODE (stmt) == SWITCH_EXPR)
4533 e = ssa_redirect_edge (e, target);
4534 e->flags = EDGE_FALLTHRU;
4542 /* Redirect E to DEST. Return NULL on failure. Otherwise, return the
4543 edge representing the redirected branch. */
4546 tree_redirect_edge_and_branch (edge e, basic_block dest)
4548 basic_block bb = e->src;
4549 block_stmt_iterator bsi;
4553 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
4556 if (e->src != ENTRY_BLOCK_PTR
4557 && (ret = tree_try_redirect_by_replacing_jump (e, dest)))
4560 if (e->dest == dest)
4563 label = tree_block_label (dest);
4565 bsi = bsi_last (bb);
4566 stmt = bsi_end_p (bsi) ? NULL : bsi_stmt (bsi);
4568 switch (stmt ? TREE_CODE (stmt) : ERROR_MARK)
4571 stmt = (e->flags & EDGE_TRUE_VALUE
4572 ? COND_EXPR_THEN (stmt)
4573 : COND_EXPR_ELSE (stmt));
4574 GOTO_DESTINATION (stmt) = label;
4578 /* No non-abnormal edges should lead from a non-simple goto, and
4579 simple ones should be represented implicitly. */
4584 tree cases = get_cases_for_edge (e, stmt);
4586 /* If we have a list of cases associated with E, then use it
4587 as it's a lot faster than walking the entire case vector. */
4590 edge e2 = find_edge (e->src, dest);
4597 CASE_LABEL (cases) = label;
4598 cases = TREE_CHAIN (cases);
4601 /* If there was already an edge in the CFG, then we need
4602 to move all the cases associated with E to E2. */
4605 tree cases2 = get_cases_for_edge (e2, stmt);
4607 TREE_CHAIN (last) = TREE_CHAIN (cases2);
4608 TREE_CHAIN (cases2) = first;
4613 tree vec = SWITCH_LABELS (stmt);
4614 size_t i, n = TREE_VEC_LENGTH (vec);
4616 for (i = 0; i < n; i++)
4618 tree elt = TREE_VEC_ELT (vec, i);
4620 if (label_to_block (CASE_LABEL (elt)) == e->dest)
4621 CASE_LABEL (elt) = label;
4630 e->flags |= EDGE_FALLTHRU;
4634 /* Otherwise it must be a fallthru edge, and we don't need to
4635 do anything besides redirecting it. */
4636 gcc_assert (e->flags & EDGE_FALLTHRU);
4640 /* Update/insert PHI nodes as necessary. */
4642 /* Now update the edges in the CFG. */
4643 e = ssa_redirect_edge (e, dest);
4649 /* Simple wrapper, as we can always redirect fallthru edges. */
4652 tree_redirect_edge_and_branch_force (edge e, basic_block dest)
4654 e = tree_redirect_edge_and_branch (e, dest);
4661 /* Splits basic block BB after statement STMT (but at least after the
4662 labels). If STMT is NULL, BB is split just after the labels. */
4665 tree_split_block (basic_block bb, void *stmt)
4667 block_stmt_iterator bsi, bsi_tgt;
4673 new_bb = create_empty_bb (bb);
4675 /* Redirect the outgoing edges. */
4676 new_bb->succs = bb->succs;
4678 FOR_EACH_EDGE (e, ei, new_bb->succs)
4681 if (stmt && TREE_CODE ((tree) stmt) == LABEL_EXPR)
4684 /* Move everything from BSI to the new basic block. */
4685 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4687 act = bsi_stmt (bsi);
4688 if (TREE_CODE (act) == LABEL_EXPR)
4701 bsi_tgt = bsi_start (new_bb);
4702 while (!bsi_end_p (bsi))
4704 act = bsi_stmt (bsi);
4706 bsi_insert_after (&bsi_tgt, act, BSI_NEW_STMT);
4713 /* Moves basic block BB after block AFTER. */
4716 tree_move_block_after (basic_block bb, basic_block after)
4718 if (bb->prev_bb == after)
4722 link_block (bb, after);
4728 /* Return true if basic_block can be duplicated. */
4731 tree_can_duplicate_bb_p (basic_block bb ATTRIBUTE_UNUSED)
4736 /* Create a duplicate of the basic block BB. NOTE: This does not
4737 preserve SSA form. */
4740 tree_duplicate_bb (basic_block bb)
4743 block_stmt_iterator bsi, bsi_tgt;
4745 ssa_op_iter op_iter;
4747 new_bb = create_empty_bb (EXIT_BLOCK_PTR->prev_bb);
4749 /* First copy the phi nodes. We do not copy phi node arguments here,
4750 since the edges are not ready yet. Keep the chain of phi nodes in
4751 the same order, so that we can add them later. */
4752 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
4754 mark_for_rewrite (PHI_RESULT (phi));
4755 create_phi_node (PHI_RESULT (phi), new_bb);
4757 set_phi_nodes (new_bb, phi_reverse (phi_nodes (new_bb)));
4759 bsi_tgt = bsi_start (new_bb);
4760 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4762 tree stmt = bsi_stmt (bsi);
4765 if (TREE_CODE (stmt) == LABEL_EXPR)
4768 /* Record the definitions. */
4769 get_stmt_operands (stmt);
4771 FOR_EACH_SSA_TREE_OPERAND (val, stmt, op_iter, SSA_OP_ALL_DEFS)
4772 mark_for_rewrite (val);
4774 copy = unshare_expr (stmt);
4776 /* Copy also the virtual operands. */
4777 get_stmt_ann (copy);
4778 copy_virtual_operands (copy, stmt);
4780 bsi_insert_after (&bsi_tgt, copy, BSI_NEW_STMT);
4786 /* Basic block BB_COPY was created by code duplication. Add phi node
4787 arguments for edges going out of BB_COPY. The blocks that were
4788 duplicated have rbi->duplicated set to one. */
4791 add_phi_args_after_copy_bb (basic_block bb_copy)
4793 basic_block bb, dest;
4796 tree phi, phi_copy, phi_next, def;
4798 bb = bb_copy->rbi->original;
4800 FOR_EACH_EDGE (e_copy, ei, bb_copy->succs)
4802 if (!phi_nodes (e_copy->dest))
4805 if (e_copy->dest->rbi->duplicated)
4806 dest = e_copy->dest->rbi->original;
4808 dest = e_copy->dest;
4810 e = find_edge (bb, dest);
4813 /* During loop unrolling the target of the latch edge is copied.
4814 In this case we are not looking for edge to dest, but to
4815 duplicated block whose original was dest. */
4816 FOR_EACH_EDGE (e, ei, bb->succs)
4817 if (e->dest->rbi->duplicated
4818 && e->dest->rbi->original == dest)
4821 gcc_assert (e != NULL);
4824 for (phi = phi_nodes (e->dest), phi_copy = phi_nodes (e_copy->dest);
4826 phi = phi_next, phi_copy = PHI_CHAIN (phi_copy))
4828 phi_next = PHI_CHAIN (phi);
4830 gcc_assert (PHI_RESULT (phi) == PHI_RESULT (phi_copy));
4831 def = PHI_ARG_DEF_FROM_EDGE (phi, e);
4832 add_phi_arg (phi_copy, def, e_copy);
4837 /* Blocks in REGION_COPY array of length N_REGION were created by
4838 duplication of basic blocks. Add phi node arguments for edges
4839 going from these blocks. */
4842 add_phi_args_after_copy (basic_block *region_copy, unsigned n_region)
4846 for (i = 0; i < n_region; i++)
4847 region_copy[i]->rbi->duplicated = 1;
4849 for (i = 0; i < n_region; i++)
4850 add_phi_args_after_copy_bb (region_copy[i]);
4852 for (i = 0; i < n_region; i++)
4853 region_copy[i]->rbi->duplicated = 0;
4856 /* Maps the old ssa name FROM_NAME to TO_NAME. */
4858 struct ssa_name_map_entry
4864 /* Hash function for ssa_name_map_entry. */
4867 ssa_name_map_entry_hash (const void *entry)
4869 const struct ssa_name_map_entry *en = entry;
4870 return SSA_NAME_VERSION (en->from_name);
4873 /* Equality function for ssa_name_map_entry. */
4876 ssa_name_map_entry_eq (const void *in_table, const void *ssa_name)
4878 const struct ssa_name_map_entry *en = in_table;
4880 return en->from_name == ssa_name;
4883 /* Allocate duplicates of ssa names in list DEFINITIONS and store the mapping
4887 allocate_ssa_names (bitmap definitions, htab_t *map)
4890 struct ssa_name_map_entry *entry;
4896 *map = htab_create (10, ssa_name_map_entry_hash,
4897 ssa_name_map_entry_eq, free);
4898 EXECUTE_IF_SET_IN_BITMAP (definitions, 0, ver, bi)
4900 name = ssa_name (ver);
4901 slot = htab_find_slot_with_hash (*map, name, SSA_NAME_VERSION (name),
4907 entry = xmalloc (sizeof (struct ssa_name_map_entry));
4908 entry->from_name = name;
4911 entry->to_name = duplicate_ssa_name (name, SSA_NAME_DEF_STMT (name));
4915 /* Rewrite the definition DEF in statement STMT to new ssa name as specified
4916 by the mapping MAP. */
4919 rewrite_to_new_ssa_names_def (def_operand_p def, tree stmt, htab_t map)
4921 tree name = DEF_FROM_PTR (def);
4922 struct ssa_name_map_entry *entry;
4924 gcc_assert (TREE_CODE (name) == SSA_NAME);
4926 entry = htab_find_with_hash (map, name, SSA_NAME_VERSION (name));
4930 SET_DEF (def, entry->to_name);
4931 SSA_NAME_DEF_STMT (entry->to_name) = stmt;
4934 /* Rewrite the USE to new ssa name as specified by the mapping MAP. */
4937 rewrite_to_new_ssa_names_use (use_operand_p use, htab_t map)
4939 tree name = USE_FROM_PTR (use);
4940 struct ssa_name_map_entry *entry;
4942 if (TREE_CODE (name) != SSA_NAME)
4945 entry = htab_find_with_hash (map, name, SSA_NAME_VERSION (name));
4949 SET_USE (use, entry->to_name);
4952 /* Rewrite the ssa names in basic block BB to new ones as specified by the
4956 rewrite_to_new_ssa_names_bb (basic_block bb, htab_t map)
4962 block_stmt_iterator bsi;
4966 v_may_def_optype v_may_defs;
4967 v_must_def_optype v_must_defs;
4970 FOR_EACH_EDGE (e, ei, bb->preds)
4971 if (e->flags & EDGE_ABNORMAL)
4974 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
4976 rewrite_to_new_ssa_names_def (PHI_RESULT_PTR (phi), phi, map);
4978 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (PHI_RESULT (phi)) = 1;
4981 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4983 stmt = bsi_stmt (bsi);
4984 get_stmt_operands (stmt);
4985 ann = stmt_ann (stmt);
4987 uses = USE_OPS (ann);
4988 for (i = 0; i < NUM_USES (uses); i++)
4989 rewrite_to_new_ssa_names_use (USE_OP_PTR (uses, i), map);
4991 defs = DEF_OPS (ann);
4992 for (i = 0; i < NUM_DEFS (defs); i++)
4993 rewrite_to_new_ssa_names_def (DEF_OP_PTR (defs, i), stmt, map);
4995 vuses = VUSE_OPS (ann);
4996 for (i = 0; i < NUM_VUSES (vuses); i++)
4997 rewrite_to_new_ssa_names_use (VUSE_OP_PTR (vuses, i), map);
4999 v_may_defs = V_MAY_DEF_OPS (ann);
5000 for (i = 0; i < NUM_V_MAY_DEFS (v_may_defs); i++)
5002 rewrite_to_new_ssa_names_use
5003 (V_MAY_DEF_OP_PTR (v_may_defs, i), map);
5004 rewrite_to_new_ssa_names_def
5005 (V_MAY_DEF_RESULT_PTR (v_may_defs, i), stmt, map);
5008 v_must_defs = V_MUST_DEF_OPS (ann);
5009 for (i = 0; i < NUM_V_MUST_DEFS (v_must_defs); i++)
5011 rewrite_to_new_ssa_names_def
5012 (V_MUST_DEF_RESULT_PTR (v_must_defs, i), stmt, map);
5013 rewrite_to_new_ssa_names_use
5014 (V_MUST_DEF_KILL_PTR (v_must_defs, i), map);
5018 FOR_EACH_EDGE (e, ei, bb->succs)
5019 for (phi = phi_nodes (e->dest); phi; phi = PHI_CHAIN (phi))
5021 rewrite_to_new_ssa_names_use
5022 (PHI_ARG_DEF_PTR_FROM_EDGE (phi, e), map);
5024 if (e->flags & EDGE_ABNORMAL)
5026 tree op = PHI_ARG_DEF_FROM_EDGE (phi, e);
5027 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op) = 1;
5032 /* Rewrite the ssa names in N_REGION blocks REGION to the new ones as specified
5033 by the mapping MAP. */
5036 rewrite_to_new_ssa_names (basic_block *region, unsigned n_region, htab_t map)
5040 for (r = 0; r < n_region; r++)
5041 rewrite_to_new_ssa_names_bb (region[r], map);
5044 /* Duplicates a REGION (set of N_REGION basic blocks) with just a single
5045 important exit edge EXIT. By important we mean that no SSA name defined
5046 inside region is live over the other exit edges of the region. All entry
5047 edges to the region must go to ENTRY->dest. The edge ENTRY is redirected
5048 to the duplicate of the region. SSA form, dominance and loop information
5049 is updated. The new basic blocks are stored to REGION_COPY in the same
5050 order as they had in REGION, provided that REGION_COPY is not NULL.
5051 The function returns false if it is unable to copy the region,
5055 tree_duplicate_sese_region (edge entry, edge exit,
5056 basic_block *region, unsigned n_region,
5057 basic_block *region_copy)
5059 unsigned i, n_doms, ver;
5060 bool free_region_copy = false, copying_header = false;
5061 struct loop *loop = entry->dest->loop_father;
5066 htab_t ssa_name_map = NULL;
5070 if (!can_copy_bbs_p (region, n_region))
5073 /* Some sanity checking. Note that we do not check for all possible
5074 missuses of the functions. I.e. if you ask to copy something weird,
5075 it will work, but the state of structures probably will not be
5078 for (i = 0; i < n_region; i++)
5080 /* We do not handle subloops, i.e. all the blocks must belong to the
5082 if (region[i]->loop_father != loop)
5085 if (region[i] != entry->dest
5086 && region[i] == loop->header)
5092 /* In case the function is used for loop header copying (which is the primary
5093 use), ensure that EXIT and its copy will be new latch and entry edges. */
5094 if (loop->header == entry->dest)
5096 copying_header = true;
5097 loop->copy = loop->outer;
5099 if (!dominated_by_p (CDI_DOMINATORS, loop->latch, exit->src))
5102 for (i = 0; i < n_region; i++)
5103 if (region[i] != exit->src
5104 && dominated_by_p (CDI_DOMINATORS, region[i], exit->src))
5110 region_copy = xmalloc (sizeof (basic_block) * n_region);
5111 free_region_copy = true;
5114 gcc_assert (!any_marked_for_rewrite_p ());
5116 /* Record blocks outside the region that are duplicated by something
5118 doms = xmalloc (sizeof (basic_block) * n_basic_blocks);
5119 n_doms = get_dominated_by_region (CDI_DOMINATORS, region, n_region, doms);
5121 copy_bbs (region, n_region, region_copy, &exit, 1, &exit_copy, loop);
5122 definitions = marked_ssa_names ();
5126 loop->header = exit->dest;
5127 loop->latch = exit->src;
5130 /* Redirect the entry and add the phi node arguments. */
5131 redirected = redirect_edge_and_branch (entry, entry->dest->rbi->copy);
5132 gcc_assert (redirected != NULL);
5133 flush_pending_stmts (entry);
5135 /* Concerning updating of dominators: We must recount dominators
5136 for entry block and its copy. Anything that is outside of the region, but
5137 was dominated by something inside needs recounting as well. */
5138 set_immediate_dominator (CDI_DOMINATORS, entry->dest, entry->src);
5139 doms[n_doms++] = entry->dest->rbi->original;
5140 iterate_fix_dominators (CDI_DOMINATORS, doms, n_doms);
5143 /* Add the other phi node arguments. */
5144 add_phi_args_after_copy (region_copy, n_region);
5146 /* Add phi nodes for definitions at exit. TODO -- once we have immediate
5147 uses, it should be possible to emit phi nodes just for definitions that
5148 are used outside region. */
5149 EXECUTE_IF_SET_IN_BITMAP (definitions, 0, ver, bi)
5151 tree name = ssa_name (ver);
5153 phi = create_phi_node (name, exit->dest);
5154 add_phi_arg (phi, name, exit);
5155 add_phi_arg (phi, name, exit_copy);
5157 SSA_NAME_DEF_STMT (name) = phi;
5160 /* And create new definitions inside region and its copy. TODO -- once we
5161 have immediate uses, it might be better to leave definitions in region
5162 unchanged, create new ssa names for phi nodes on exit, and rewrite
5163 the uses, to avoid changing the copied region. */
5164 allocate_ssa_names (definitions, &ssa_name_map);
5165 rewrite_to_new_ssa_names (region, n_region, ssa_name_map);
5166 allocate_ssa_names (definitions, &ssa_name_map);
5167 rewrite_to_new_ssa_names (region_copy, n_region, ssa_name_map);
5168 htab_delete (ssa_name_map);
5170 if (free_region_copy)
5173 unmark_all_for_rewrite ();
5174 BITMAP_FREE (definitions);
5179 /* Dump FUNCTION_DECL FN to file FILE using FLAGS (see TDF_* in tree.h) */
5182 dump_function_to_file (tree fn, FILE *file, int flags)
5184 tree arg, vars, var;
5185 bool ignore_topmost_bind = false, any_var = false;
5189 fprintf (file, "%s (", lang_hooks.decl_printable_name (fn, 2));
5191 arg = DECL_ARGUMENTS (fn);
5194 print_generic_expr (file, arg, dump_flags);
5195 if (TREE_CHAIN (arg))
5196 fprintf (file, ", ");
5197 arg = TREE_CHAIN (arg);
5199 fprintf (file, ")\n");
5201 if (flags & TDF_RAW)
5203 dump_node (fn, TDF_SLIM | flags, file);
5207 /* When GIMPLE is lowered, the variables are no longer available in
5208 BIND_EXPRs, so display them separately. */
5209 if (cfun && cfun->unexpanded_var_list)
5211 ignore_topmost_bind = true;
5213 fprintf (file, "{\n");
5214 for (vars = cfun->unexpanded_var_list; vars; vars = TREE_CHAIN (vars))
5216 var = TREE_VALUE (vars);
5218 print_generic_decl (file, var, flags);
5219 fprintf (file, "\n");
5225 if (basic_block_info)
5227 /* Make a CFG based dump. */
5228 check_bb_profile (ENTRY_BLOCK_PTR, file);
5229 if (!ignore_topmost_bind)
5230 fprintf (file, "{\n");
5232 if (any_var && n_basic_blocks)
5233 fprintf (file, "\n");
5236 dump_generic_bb (file, bb, 2, flags);
5238 fprintf (file, "}\n");
5239 check_bb_profile (EXIT_BLOCK_PTR, file);
5245 /* Make a tree based dump. */
5246 chain = DECL_SAVED_TREE (fn);
5248 if (TREE_CODE (chain) == BIND_EXPR)
5250 if (ignore_topmost_bind)
5252 chain = BIND_EXPR_BODY (chain);
5260 if (!ignore_topmost_bind)
5261 fprintf (file, "{\n");
5266 fprintf (file, "\n");
5268 print_generic_stmt_indented (file, chain, flags, indent);
5269 if (ignore_topmost_bind)
5270 fprintf (file, "}\n");
5273 fprintf (file, "\n\n");
5277 /* Pretty print of the loops intermediate representation. */
5278 static void print_loop (FILE *, struct loop *, int);
5279 static void print_pred_bbs (FILE *, basic_block bb);
5280 static void print_succ_bbs (FILE *, basic_block bb);
5283 /* Print the predecessors indexes of edge E on FILE. */
5286 print_pred_bbs (FILE *file, basic_block bb)
5291 FOR_EACH_EDGE (e, ei, bb->preds)
5292 fprintf (file, "bb_%d", e->src->index);
5296 /* Print the successors indexes of edge E on FILE. */
5299 print_succ_bbs (FILE *file, basic_block bb)
5304 FOR_EACH_EDGE (e, ei, bb->succs)
5305 fprintf (file, "bb_%d", e->src->index);
5309 /* Pretty print LOOP on FILE, indented INDENT spaces. */
5312 print_loop (FILE *file, struct loop *loop, int indent)
5320 s_indent = (char *) alloca ((size_t) indent + 1);
5321 memset ((void *) s_indent, ' ', (size_t) indent);
5322 s_indent[indent] = '\0';
5324 /* Print the loop's header. */
5325 fprintf (file, "%sloop_%d\n", s_indent, loop->num);
5327 /* Print the loop's body. */
5328 fprintf (file, "%s{\n", s_indent);
5330 if (bb->loop_father == loop)
5332 /* Print the basic_block's header. */
5333 fprintf (file, "%s bb_%d (preds = {", s_indent, bb->index);
5334 print_pred_bbs (file, bb);
5335 fprintf (file, "}, succs = {");
5336 print_succ_bbs (file, bb);
5337 fprintf (file, "})\n");
5339 /* Print the basic_block's body. */
5340 fprintf (file, "%s {\n", s_indent);
5341 tree_dump_bb (bb, file, indent + 4);
5342 fprintf (file, "%s }\n", s_indent);
5345 print_loop (file, loop->inner, indent + 2);
5346 fprintf (file, "%s}\n", s_indent);
5347 print_loop (file, loop->next, indent);
5351 /* Follow a CFG edge from the entry point of the program, and on entry
5352 of a loop, pretty print the loop structure on FILE. */
5355 print_loop_ir (FILE *file)
5359 bb = BASIC_BLOCK (0);
5360 if (bb && bb->loop_father)
5361 print_loop (file, bb->loop_father, 0);
5365 /* Debugging loops structure at tree level. */
5368 debug_loop_ir (void)
5370 print_loop_ir (stderr);
5374 /* Return true if BB ends with a call, possibly followed by some
5375 instructions that must stay with the call. Return false,
5379 tree_block_ends_with_call_p (basic_block bb)
5381 block_stmt_iterator bsi = bsi_last (bb);
5382 return get_call_expr_in (bsi_stmt (bsi)) != NULL;
5386 /* Return true if BB ends with a conditional branch. Return false,
5390 tree_block_ends_with_condjump_p (basic_block bb)
5392 tree stmt = tsi_stmt (bsi_last (bb).tsi);
5393 return (TREE_CODE (stmt) == COND_EXPR);
5397 /* Return true if we need to add fake edge to exit at statement T.
5398 Helper function for tree_flow_call_edges_add. */
5401 need_fake_edge_p (tree t)
5405 /* NORETURN and LONGJMP calls already have an edge to exit.
5406 CONST and PURE calls do not need one.
5407 We don't currently check for CONST and PURE here, although
5408 it would be a good idea, because those attributes are
5409 figured out from the RTL in mark_constant_function, and
5410 the counter incrementation code from -fprofile-arcs
5411 leads to different results from -fbranch-probabilities. */
5412 call = get_call_expr_in (t);
5414 && !(call_expr_flags (call) & ECF_NORETURN))
5417 if (TREE_CODE (t) == ASM_EXPR
5418 && (ASM_VOLATILE_P (t) || ASM_INPUT_P (t)))
5425 /* Add fake edges to the function exit for any non constant and non
5426 noreturn calls, volatile inline assembly in the bitmap of blocks
5427 specified by BLOCKS or to the whole CFG if BLOCKS is zero. Return
5428 the number of blocks that were split.
5430 The goal is to expose cases in which entering a basic block does
5431 not imply that all subsequent instructions must be executed. */
5434 tree_flow_call_edges_add (sbitmap blocks)
5437 int blocks_split = 0;
5438 int last_bb = last_basic_block;
5439 bool check_last_block = false;
5441 if (n_basic_blocks == 0)
5445 check_last_block = true;
5447 check_last_block = TEST_BIT (blocks, EXIT_BLOCK_PTR->prev_bb->index);
5449 /* In the last basic block, before epilogue generation, there will be
5450 a fallthru edge to EXIT. Special care is required if the last insn
5451 of the last basic block is a call because make_edge folds duplicate
5452 edges, which would result in the fallthru edge also being marked
5453 fake, which would result in the fallthru edge being removed by
5454 remove_fake_edges, which would result in an invalid CFG.
5456 Moreover, we can't elide the outgoing fake edge, since the block
5457 profiler needs to take this into account in order to solve the minimal
5458 spanning tree in the case that the call doesn't return.
5460 Handle this by adding a dummy instruction in a new last basic block. */
5461 if (check_last_block)
5463 basic_block bb = EXIT_BLOCK_PTR->prev_bb;
5464 block_stmt_iterator bsi = bsi_last (bb);
5466 if (!bsi_end_p (bsi))
5469 if (need_fake_edge_p (t))
5473 e = find_edge (bb, EXIT_BLOCK_PTR);
5476 bsi_insert_on_edge (e, build_empty_stmt ());
5477 bsi_commit_edge_inserts ();
5482 /* Now add fake edges to the function exit for any non constant
5483 calls since there is no way that we can determine if they will
5485 for (i = 0; i < last_bb; i++)
5487 basic_block bb = BASIC_BLOCK (i);
5488 block_stmt_iterator bsi;
5489 tree stmt, last_stmt;
5494 if (blocks && !TEST_BIT (blocks, i))
5497 bsi = bsi_last (bb);
5498 if (!bsi_end_p (bsi))
5500 last_stmt = bsi_stmt (bsi);
5503 stmt = bsi_stmt (bsi);
5504 if (need_fake_edge_p (stmt))
5507 /* The handling above of the final block before the
5508 epilogue should be enough to verify that there is
5509 no edge to the exit block in CFG already.
5510 Calling make_edge in such case would cause us to
5511 mark that edge as fake and remove it later. */
5512 #ifdef ENABLE_CHECKING
5513 if (stmt == last_stmt)
5515 e = find_edge (bb, EXIT_BLOCK_PTR);
5516 gcc_assert (e == NULL);
5520 /* Note that the following may create a new basic block
5521 and renumber the existing basic blocks. */
5522 if (stmt != last_stmt)
5524 e = split_block (bb, stmt);
5528 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
5532 while (!bsi_end_p (bsi));
5537 verify_flow_info ();
5539 return blocks_split;
5543 tree_purge_dead_eh_edges (basic_block bb)
5545 bool changed = false;
5548 tree stmt = last_stmt (bb);
5550 if (stmt && tree_can_throw_internal (stmt))
5553 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
5555 if (e->flags & EDGE_EH)
5564 /* Removal of dead EH edges might change dominators of not
5565 just immediate successors. E.g. when bb1 is changed so that
5566 it no longer can throw and bb1->bb3 and bb1->bb4 are dead
5567 eh edges purged by this function in:
5579 idom(bb5) must be recomputed. For now just free the dominance
5582 free_dominance_info (CDI_DOMINATORS);
5588 tree_purge_all_dead_eh_edges (bitmap blocks)
5590 bool changed = false;
5594 EXECUTE_IF_SET_IN_BITMAP (blocks, 0, i, bi)
5596 changed |= tree_purge_dead_eh_edges (BASIC_BLOCK (i));
5602 /* This function is called whenever a new edge is created or
5606 tree_execute_on_growing_pred (edge e)
5608 basic_block bb = e->dest;
5611 reserve_phi_args_for_new_edge (bb);
5614 /* This function is called immediately before edge E is removed from
5615 the edge vector E->dest->preds. */
5618 tree_execute_on_shrinking_pred (edge e)
5620 if (phi_nodes (e->dest))
5621 remove_phi_args (e);
5624 struct cfg_hooks tree_cfg_hooks = {
5626 tree_verify_flow_info,
5627 tree_dump_bb, /* dump_bb */
5628 create_bb, /* create_basic_block */
5629 tree_redirect_edge_and_branch,/* redirect_edge_and_branch */
5630 tree_redirect_edge_and_branch_force,/* redirect_edge_and_branch_force */
5631 remove_bb, /* delete_basic_block */
5632 tree_split_block, /* split_block */
5633 tree_move_block_after, /* move_block_after */
5634 tree_can_merge_blocks_p, /* can_merge_blocks_p */
5635 tree_merge_blocks, /* merge_blocks */
5636 tree_predict_edge, /* predict_edge */
5637 tree_predicted_by_p, /* predicted_by_p */
5638 tree_can_duplicate_bb_p, /* can_duplicate_block_p */
5639 tree_duplicate_bb, /* duplicate_block */
5640 tree_split_edge, /* split_edge */
5641 tree_make_forwarder_block, /* make_forward_block */
5642 NULL, /* tidy_fallthru_edge */
5643 tree_block_ends_with_call_p, /* block_ends_with_call_p */
5644 tree_block_ends_with_condjump_p, /* block_ends_with_condjump_p */
5645 tree_flow_call_edges_add, /* flow_call_edges_add */
5646 tree_execute_on_growing_pred, /* execute_on_growing_pred */
5647 tree_execute_on_shrinking_pred, /* execute_on_shrinking_pred */
5651 /* Split all critical edges. */
5654 split_critical_edges (void)
5660 /* split_edge can redirect edges out of SWITCH_EXPRs, which can get
5661 expensive. So we want to enable recording of edge to CASE_LABEL_EXPR
5662 mappings around the calls to split_edge. */
5663 start_recording_case_labels ();
5666 FOR_EACH_EDGE (e, ei, bb->succs)
5667 if (EDGE_CRITICAL_P (e) && !(e->flags & EDGE_ABNORMAL))
5672 end_recording_case_labels ();
5675 struct tree_opt_pass pass_split_crit_edges =
5677 "crited", /* name */
5679 split_critical_edges, /* execute */
5682 0, /* static_pass_number */
5683 TV_TREE_SPLIT_EDGES, /* tv_id */
5684 PROP_cfg, /* properties required */
5685 PROP_no_crit_edges, /* properties_provided */
5686 0, /* properties_destroyed */
5687 0, /* todo_flags_start */
5688 TODO_dump_func, /* todo_flags_finish */
5693 /* Return EXP if it is a valid GIMPLE rvalue, else gimplify it into
5694 a temporary, make sure and register it to be renamed if necessary,
5695 and finally return the temporary. Put the statements to compute
5696 EXP before the current statement in BSI. */
5699 gimplify_val (block_stmt_iterator *bsi, tree type, tree exp)
5701 tree t, new_stmt, orig_stmt;
5703 if (is_gimple_val (exp))
5706 t = make_rename_temp (type, NULL);
5707 new_stmt = build (MODIFY_EXPR, type, t, exp);
5709 orig_stmt = bsi_stmt (*bsi);
5710 SET_EXPR_LOCUS (new_stmt, EXPR_LOCUS (orig_stmt));
5711 TREE_BLOCK (new_stmt) = TREE_BLOCK (orig_stmt);
5713 bsi_insert_before (bsi, new_stmt, BSI_SAME_STMT);
5718 /* Build a ternary operation and gimplify it. Emit code before BSI.
5719 Return the gimple_val holding the result. */
5722 gimplify_build3 (block_stmt_iterator *bsi, enum tree_code code,
5723 tree type, tree a, tree b, tree c)
5727 ret = fold (build3 (code, type, a, b, c));
5730 return gimplify_val (bsi, type, ret);
5733 /* Build a binary operation and gimplify it. Emit code before BSI.
5734 Return the gimple_val holding the result. */
5737 gimplify_build2 (block_stmt_iterator *bsi, enum tree_code code,
5738 tree type, tree a, tree b)
5742 ret = fold (build2 (code, type, a, b));
5745 return gimplify_val (bsi, type, ret);
5748 /* Build a unary operation and gimplify it. Emit code before BSI.
5749 Return the gimple_val holding the result. */
5752 gimplify_build1 (block_stmt_iterator *bsi, enum tree_code code, tree type,
5757 ret = fold (build1 (code, type, a));
5760 return gimplify_val (bsi, type, ret);
5765 /* Emit return warnings. */
5768 execute_warn_function_return (void)
5770 #ifdef USE_MAPPED_LOCATION
5771 source_location location;
5779 if (warn_missing_noreturn
5780 && !TREE_THIS_VOLATILE (cfun->decl)
5781 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) == 0
5782 && !lang_hooks.function.missing_noreturn_ok_p (cfun->decl))
5783 warning ("%Jfunction might be possible candidate for "
5784 "attribute %<noreturn%>",
5787 /* If we have a path to EXIT, then we do return. */
5788 if (TREE_THIS_VOLATILE (cfun->decl)
5789 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) > 0)
5791 #ifdef USE_MAPPED_LOCATION
5792 location = UNKNOWN_LOCATION;
5796 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
5798 last = last_stmt (e->src);
5799 if (TREE_CODE (last) == RETURN_EXPR
5800 #ifdef USE_MAPPED_LOCATION
5801 && (location = EXPR_LOCATION (last)) != UNKNOWN_LOCATION)
5803 && (locus = EXPR_LOCUS (last)) != NULL)
5807 #ifdef USE_MAPPED_LOCATION
5808 if (location == UNKNOWN_LOCATION)
5809 location = cfun->function_end_locus;
5810 warning ("%H%<noreturn%> function does return", &location);
5813 locus = &cfun->function_end_locus;
5814 warning ("%H%<noreturn%> function does return", locus);
5818 /* If we see "return;" in some basic block, then we do reach the end
5819 without returning a value. */
5820 else if (warn_return_type
5821 && !TREE_NO_WARNING (cfun->decl)
5822 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) > 0
5823 && !VOID_TYPE_P (TREE_TYPE (TREE_TYPE (cfun->decl))))
5825 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
5827 tree last = last_stmt (e->src);
5828 if (TREE_CODE (last) == RETURN_EXPR
5829 && TREE_OPERAND (last, 0) == NULL)
5831 #ifdef USE_MAPPED_LOCATION
5832 location = EXPR_LOCATION (last);
5833 if (location == UNKNOWN_LOCATION)
5834 location = cfun->function_end_locus;
5835 warning ("%Hcontrol reaches end of non-void function", &location);
5837 locus = EXPR_LOCUS (last);
5839 locus = &cfun->function_end_locus;
5840 warning ("%Hcontrol reaches end of non-void function", locus);
5842 TREE_NO_WARNING (cfun->decl) = 1;
5850 /* Given a basic block B which ends with a conditional and has
5851 precisely two successors, determine which of the edges is taken if
5852 the conditional is true and which is taken if the conditional is
5853 false. Set TRUE_EDGE and FALSE_EDGE appropriately. */
5856 extract_true_false_edges_from_block (basic_block b,
5860 edge e = EDGE_SUCC (b, 0);
5862 if (e->flags & EDGE_TRUE_VALUE)
5865 *false_edge = EDGE_SUCC (b, 1);
5870 *true_edge = EDGE_SUCC (b, 1);
5874 struct tree_opt_pass pass_warn_function_return =
5878 execute_warn_function_return, /* execute */
5881 0, /* static_pass_number */
5883 PROP_cfg, /* properties_required */
5884 0, /* properties_provided */
5885 0, /* properties_destroyed */
5886 0, /* todo_flags_start */
5887 0, /* todo_flags_finish */
5891 #include "gt-tree-cfg.h"