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 cfg and repair loop structures. */
965 cleanup_tree_cfg_loop (void)
967 bitmap changed_bbs = BITMAP_ALLOC (NULL);
971 fix_loop_structure (current_loops, changed_bbs);
972 calculate_dominance_info (CDI_DOMINATORS);
974 /* This usually does nothing. But sometimes parts of cfg that originally
975 were inside a loop get out of it due to edge removal (since they
976 become unreachable by back edges from latch). */
977 rewrite_into_loop_closed_ssa (changed_bbs);
979 BITMAP_FREE (changed_bbs);
981 #ifdef ENABLE_CHECKING
982 verify_loop_structure (current_loops);
986 /* Cleanup useless labels in basic blocks. This is something we wish
987 to do early because it allows us to group case labels before creating
988 the edges for the CFG, and it speeds up block statement iterators in
990 We only run this pass once, running it more than once is probably not
993 /* A map from basic block index to the leading label of that block. */
994 static tree *label_for_bb;
996 /* Callback for for_each_eh_region. Helper for cleanup_dead_labels. */
998 update_eh_label (struct eh_region *region)
1000 tree old_label = get_eh_region_tree_label (region);
1004 basic_block bb = label_to_block (old_label);
1006 /* ??? After optimizing, there may be EH regions with labels
1007 that have already been removed from the function body, so
1008 there is no basic block for them. */
1012 new_label = label_for_bb[bb->index];
1013 set_eh_region_tree_label (region, new_label);
1017 /* Given LABEL return the first label in the same basic block. */
1019 main_block_label (tree label)
1021 basic_block bb = label_to_block (label);
1023 /* label_to_block possibly inserted undefined label into the chain. */
1024 if (!label_for_bb[bb->index])
1025 label_for_bb[bb->index] = label;
1026 return label_for_bb[bb->index];
1029 /* Cleanup redundant labels. This is a three-step process:
1030 1) Find the leading label for each block.
1031 2) Redirect all references to labels to the leading labels.
1032 3) Cleanup all useless labels. */
1035 cleanup_dead_labels (void)
1038 label_for_bb = xcalloc (last_basic_block, sizeof (tree));
1040 /* Find a suitable label for each block. We use the first user-defined
1041 label if there is one, or otherwise just the first label we see. */
1044 block_stmt_iterator i;
1046 for (i = bsi_start (bb); !bsi_end_p (i); bsi_next (&i))
1048 tree label, stmt = bsi_stmt (i);
1050 if (TREE_CODE (stmt) != LABEL_EXPR)
1053 label = LABEL_EXPR_LABEL (stmt);
1055 /* If we have not yet seen a label for the current block,
1056 remember this one and see if there are more labels. */
1057 if (! label_for_bb[bb->index])
1059 label_for_bb[bb->index] = label;
1063 /* If we did see a label for the current block already, but it
1064 is an artificially created label, replace it if the current
1065 label is a user defined label. */
1066 if (! DECL_ARTIFICIAL (label)
1067 && DECL_ARTIFICIAL (label_for_bb[bb->index]))
1069 label_for_bb[bb->index] = label;
1075 /* Now redirect all jumps/branches to the selected label.
1076 First do so for each block ending in a control statement. */
1079 tree stmt = last_stmt (bb);
1083 switch (TREE_CODE (stmt))
1087 tree true_branch, false_branch;
1089 true_branch = COND_EXPR_THEN (stmt);
1090 false_branch = COND_EXPR_ELSE (stmt);
1092 GOTO_DESTINATION (true_branch)
1093 = main_block_label (GOTO_DESTINATION (true_branch));
1094 GOTO_DESTINATION (false_branch)
1095 = main_block_label (GOTO_DESTINATION (false_branch));
1103 tree vec = SWITCH_LABELS (stmt);
1104 size_t n = TREE_VEC_LENGTH (vec);
1106 /* Replace all destination labels. */
1107 for (i = 0; i < n; ++i)
1109 tree elt = TREE_VEC_ELT (vec, i);
1110 tree label = main_block_label (CASE_LABEL (elt));
1111 CASE_LABEL (elt) = label;
1116 /* We have to handle GOTO_EXPRs until they're removed, and we don't
1117 remove them until after we've created the CFG edges. */
1119 if (! computed_goto_p (stmt))
1121 GOTO_DESTINATION (stmt)
1122 = main_block_label (GOTO_DESTINATION (stmt));
1131 for_each_eh_region (update_eh_label);
1133 /* Finally, purge dead labels. All user-defined labels and labels that
1134 can be the target of non-local gotos are preserved. */
1137 block_stmt_iterator i;
1138 tree label_for_this_bb = label_for_bb[bb->index];
1140 if (! label_for_this_bb)
1143 for (i = bsi_start (bb); !bsi_end_p (i); )
1145 tree label, stmt = bsi_stmt (i);
1147 if (TREE_CODE (stmt) != LABEL_EXPR)
1150 label = LABEL_EXPR_LABEL (stmt);
1152 if (label == label_for_this_bb
1153 || ! DECL_ARTIFICIAL (label)
1154 || DECL_NONLOCAL (label))
1161 free (label_for_bb);
1164 /* Look for blocks ending in a multiway branch (a SWITCH_EXPR in GIMPLE),
1165 and scan the sorted vector of cases. Combine the ones jumping to the
1167 Eg. three separate entries 1: 2: 3: become one entry 1..3: */
1170 group_case_labels (void)
1176 tree stmt = last_stmt (bb);
1177 if (stmt && TREE_CODE (stmt) == SWITCH_EXPR)
1179 tree labels = SWITCH_LABELS (stmt);
1180 int old_size = TREE_VEC_LENGTH (labels);
1181 int i, j, new_size = old_size;
1182 tree default_case = TREE_VEC_ELT (labels, old_size - 1);
1185 /* The default label is always the last case in a switch
1186 statement after gimplification. */
1187 default_label = CASE_LABEL (default_case);
1189 /* Look for possible opportunities to merge cases.
1190 Ignore the last element of the label vector because it
1191 must be the default case. */
1193 while (i < old_size - 1)
1195 tree base_case, base_label, base_high, type;
1196 base_case = TREE_VEC_ELT (labels, i);
1198 gcc_assert (base_case);
1199 base_label = CASE_LABEL (base_case);
1201 /* Discard cases that have the same destination as the
1203 if (base_label == default_label)
1205 TREE_VEC_ELT (labels, i) = NULL_TREE;
1211 type = TREE_TYPE (CASE_LOW (base_case));
1212 base_high = CASE_HIGH (base_case) ?
1213 CASE_HIGH (base_case) : CASE_LOW (base_case);
1215 /* Try to merge case labels. Break out when we reach the end
1216 of the label vector or when we cannot merge the next case
1217 label with the current one. */
1218 while (i < old_size - 1)
1220 tree merge_case = TREE_VEC_ELT (labels, i);
1221 tree merge_label = CASE_LABEL (merge_case);
1222 tree t = int_const_binop (PLUS_EXPR, base_high,
1223 integer_one_node, 1);
1225 /* Merge the cases if they jump to the same place,
1226 and their ranges are consecutive. */
1227 if (merge_label == base_label
1228 && tree_int_cst_equal (CASE_LOW (merge_case), t))
1230 base_high = CASE_HIGH (merge_case) ?
1231 CASE_HIGH (merge_case) : CASE_LOW (merge_case);
1232 CASE_HIGH (base_case) = base_high;
1233 TREE_VEC_ELT (labels, i) = NULL_TREE;
1242 /* Compress the case labels in the label vector, and adjust the
1243 length of the vector. */
1244 for (i = 0, j = 0; i < new_size; i++)
1246 while (! TREE_VEC_ELT (labels, j))
1248 TREE_VEC_ELT (labels, i) = TREE_VEC_ELT (labels, j++);
1250 TREE_VEC_LENGTH (labels) = new_size;
1255 /* Checks whether we can merge block B into block A. */
1258 tree_can_merge_blocks_p (basic_block a, basic_block b)
1261 block_stmt_iterator bsi;
1263 if (EDGE_COUNT (a->succs) != 1)
1266 if (EDGE_SUCC (a, 0)->flags & EDGE_ABNORMAL)
1269 if (EDGE_SUCC (a, 0)->dest != b)
1272 if (EDGE_COUNT (b->preds) > 1)
1275 if (b == EXIT_BLOCK_PTR)
1278 /* If A ends by a statement causing exceptions or something similar, we
1279 cannot merge the blocks. */
1280 stmt = last_stmt (a);
1281 if (stmt && stmt_ends_bb_p (stmt))
1284 /* Do not allow a block with only a non-local label to be merged. */
1285 if (stmt && TREE_CODE (stmt) == LABEL_EXPR
1286 && DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)))
1289 /* There may be no phi nodes at the start of b. Most of these degenerate
1290 phi nodes should be cleaned up by kill_redundant_phi_nodes. */
1294 /* Do not remove user labels. */
1295 for (bsi = bsi_start (b); !bsi_end_p (bsi); bsi_next (&bsi))
1297 stmt = bsi_stmt (bsi);
1298 if (TREE_CODE (stmt) != LABEL_EXPR)
1300 if (!DECL_ARTIFICIAL (LABEL_EXPR_LABEL (stmt)))
1304 /* Protect the loop latches. */
1306 && b->loop_father->latch == b)
1313 /* Merge block B into block A. */
1316 tree_merge_blocks (basic_block a, basic_block b)
1318 block_stmt_iterator bsi;
1319 tree_stmt_iterator last;
1322 fprintf (dump_file, "Merging blocks %d and %d\n", a->index, b->index);
1324 /* Ensure that B follows A. */
1325 move_block_after (b, a);
1327 gcc_assert (EDGE_SUCC (a, 0)->flags & EDGE_FALLTHRU);
1328 gcc_assert (!last_stmt (a) || !stmt_ends_bb_p (last_stmt (a)));
1330 /* Remove labels from B and set bb_for_stmt to A for other statements. */
1331 for (bsi = bsi_start (b); !bsi_end_p (bsi);)
1333 if (TREE_CODE (bsi_stmt (bsi)) == LABEL_EXPR)
1335 tree label = bsi_stmt (bsi);
1338 /* Now that we can thread computed gotos, we might have
1339 a situation where we have a forced label in block B
1340 However, the label at the start of block B might still be
1341 used in other ways (think about the runtime checking for
1342 Fortran assigned gotos). So we can not just delete the
1343 label. Instead we move the label to the start of block A. */
1344 if (FORCED_LABEL (LABEL_EXPR_LABEL (label)))
1346 block_stmt_iterator dest_bsi = bsi_start (a);
1347 bsi_insert_before (&dest_bsi, label, BSI_NEW_STMT);
1352 set_bb_for_stmt (bsi_stmt (bsi), a);
1357 /* Merge the chains. */
1358 last = tsi_last (a->stmt_list);
1359 tsi_link_after (&last, b->stmt_list, TSI_NEW_STMT);
1360 b->stmt_list = NULL;
1364 /* Walk the function tree removing unnecessary statements.
1366 * Empty statement nodes are removed
1368 * Unnecessary TRY_FINALLY and TRY_CATCH blocks are removed
1370 * Unnecessary COND_EXPRs are removed
1372 * Some unnecessary BIND_EXPRs are removed
1374 Clearly more work could be done. The trick is doing the analysis
1375 and removal fast enough to be a net improvement in compile times.
1377 Note that when we remove a control structure such as a COND_EXPR
1378 BIND_EXPR, or TRY block, we will need to repeat this optimization pass
1379 to ensure we eliminate all the useless code. */
1390 static void remove_useless_stmts_1 (tree *, struct rus_data *);
1393 remove_useless_stmts_warn_notreached (tree stmt)
1395 if (EXPR_HAS_LOCATION (stmt))
1397 location_t loc = EXPR_LOCATION (stmt);
1398 if (LOCATION_LINE (loc) > 0)
1400 warning ("%Hwill never be executed", &loc);
1405 switch (TREE_CODE (stmt))
1407 case STATEMENT_LIST:
1409 tree_stmt_iterator i;
1410 for (i = tsi_start (stmt); !tsi_end_p (i); tsi_next (&i))
1411 if (remove_useless_stmts_warn_notreached (tsi_stmt (i)))
1417 if (remove_useless_stmts_warn_notreached (COND_EXPR_COND (stmt)))
1419 if (remove_useless_stmts_warn_notreached (COND_EXPR_THEN (stmt)))
1421 if (remove_useless_stmts_warn_notreached (COND_EXPR_ELSE (stmt)))
1425 case TRY_FINALLY_EXPR:
1426 case TRY_CATCH_EXPR:
1427 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt, 0)))
1429 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt, 1)))
1434 return remove_useless_stmts_warn_notreached (CATCH_BODY (stmt));
1435 case EH_FILTER_EXPR:
1436 return remove_useless_stmts_warn_notreached (EH_FILTER_FAILURE (stmt));
1438 return remove_useless_stmts_warn_notreached (BIND_EXPR_BLOCK (stmt));
1441 /* Not a live container. */
1449 remove_useless_stmts_cond (tree *stmt_p, struct rus_data *data)
1451 tree then_clause, else_clause, cond;
1452 bool save_has_label, then_has_label, else_has_label;
1454 save_has_label = data->has_label;
1455 data->has_label = false;
1456 data->last_goto = NULL;
1458 remove_useless_stmts_1 (&COND_EXPR_THEN (*stmt_p), data);
1460 then_has_label = data->has_label;
1461 data->has_label = false;
1462 data->last_goto = NULL;
1464 remove_useless_stmts_1 (&COND_EXPR_ELSE (*stmt_p), data);
1466 else_has_label = data->has_label;
1467 data->has_label = save_has_label | then_has_label | else_has_label;
1469 then_clause = COND_EXPR_THEN (*stmt_p);
1470 else_clause = COND_EXPR_ELSE (*stmt_p);
1471 cond = fold (COND_EXPR_COND (*stmt_p));
1473 /* If neither arm does anything at all, we can remove the whole IF. */
1474 if (!TREE_SIDE_EFFECTS (then_clause) && !TREE_SIDE_EFFECTS (else_clause))
1476 *stmt_p = build_empty_stmt ();
1477 data->repeat = true;
1480 /* If there are no reachable statements in an arm, then we can
1481 zap the entire conditional. */
1482 else if (integer_nonzerop (cond) && !else_has_label)
1484 if (warn_notreached)
1485 remove_useless_stmts_warn_notreached (else_clause);
1486 *stmt_p = then_clause;
1487 data->repeat = true;
1489 else if (integer_zerop (cond) && !then_has_label)
1491 if (warn_notreached)
1492 remove_useless_stmts_warn_notreached (then_clause);
1493 *stmt_p = else_clause;
1494 data->repeat = true;
1497 /* Check a couple of simple things on then/else with single stmts. */
1500 tree then_stmt = expr_only (then_clause);
1501 tree else_stmt = expr_only (else_clause);
1503 /* Notice branches to a common destination. */
1504 if (then_stmt && else_stmt
1505 && TREE_CODE (then_stmt) == GOTO_EXPR
1506 && TREE_CODE (else_stmt) == GOTO_EXPR
1507 && (GOTO_DESTINATION (then_stmt) == GOTO_DESTINATION (else_stmt)))
1509 *stmt_p = then_stmt;
1510 data->repeat = true;
1513 /* If the THEN/ELSE clause merely assigns a value to a variable or
1514 parameter which is already known to contain that value, then
1515 remove the useless THEN/ELSE clause. */
1516 else if (TREE_CODE (cond) == VAR_DECL || TREE_CODE (cond) == PARM_DECL)
1519 && TREE_CODE (else_stmt) == MODIFY_EXPR
1520 && TREE_OPERAND (else_stmt, 0) == cond
1521 && integer_zerop (TREE_OPERAND (else_stmt, 1)))
1522 COND_EXPR_ELSE (*stmt_p) = alloc_stmt_list ();
1524 else if ((TREE_CODE (cond) == EQ_EXPR || TREE_CODE (cond) == NE_EXPR)
1525 && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL
1526 || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL)
1527 && TREE_CONSTANT (TREE_OPERAND (cond, 1)))
1529 tree stmt = (TREE_CODE (cond) == EQ_EXPR
1530 ? then_stmt : else_stmt);
1531 tree *location = (TREE_CODE (cond) == EQ_EXPR
1532 ? &COND_EXPR_THEN (*stmt_p)
1533 : &COND_EXPR_ELSE (*stmt_p));
1536 && TREE_CODE (stmt) == MODIFY_EXPR
1537 && TREE_OPERAND (stmt, 0) == TREE_OPERAND (cond, 0)
1538 && TREE_OPERAND (stmt, 1) == TREE_OPERAND (cond, 1))
1539 *location = alloc_stmt_list ();
1543 /* Protect GOTOs in the arm of COND_EXPRs from being removed. They
1544 would be re-introduced during lowering. */
1545 data->last_goto = NULL;
1550 remove_useless_stmts_tf (tree *stmt_p, struct rus_data *data)
1552 bool save_may_branch, save_may_throw;
1553 bool this_may_branch, this_may_throw;
1555 /* Collect may_branch and may_throw information for the body only. */
1556 save_may_branch = data->may_branch;
1557 save_may_throw = data->may_throw;
1558 data->may_branch = false;
1559 data->may_throw = false;
1560 data->last_goto = NULL;
1562 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 0), data);
1564 this_may_branch = data->may_branch;
1565 this_may_throw = data->may_throw;
1566 data->may_branch |= save_may_branch;
1567 data->may_throw |= save_may_throw;
1568 data->last_goto = NULL;
1570 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 1), data);
1572 /* If the body is empty, then we can emit the FINALLY block without
1573 the enclosing TRY_FINALLY_EXPR. */
1574 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 0)))
1576 *stmt_p = TREE_OPERAND (*stmt_p, 1);
1577 data->repeat = true;
1580 /* If the handler is empty, then we can emit the TRY block without
1581 the enclosing TRY_FINALLY_EXPR. */
1582 else if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 1)))
1584 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1585 data->repeat = true;
1588 /* If the body neither throws, nor branches, then we can safely
1589 string the TRY and FINALLY blocks together. */
1590 else if (!this_may_branch && !this_may_throw)
1592 tree stmt = *stmt_p;
1593 *stmt_p = TREE_OPERAND (stmt, 0);
1594 append_to_statement_list (TREE_OPERAND (stmt, 1), stmt_p);
1595 data->repeat = true;
1601 remove_useless_stmts_tc (tree *stmt_p, struct rus_data *data)
1603 bool save_may_throw, this_may_throw;
1604 tree_stmt_iterator i;
1607 /* Collect may_throw information for the body only. */
1608 save_may_throw = data->may_throw;
1609 data->may_throw = false;
1610 data->last_goto = NULL;
1612 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 0), data);
1614 this_may_throw = data->may_throw;
1615 data->may_throw = save_may_throw;
1617 /* If the body cannot throw, then we can drop the entire TRY_CATCH_EXPR. */
1618 if (!this_may_throw)
1620 if (warn_notreached)
1621 remove_useless_stmts_warn_notreached (TREE_OPERAND (*stmt_p, 1));
1622 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1623 data->repeat = true;
1627 /* Process the catch clause specially. We may be able to tell that
1628 no exceptions propagate past this point. */
1630 this_may_throw = true;
1631 i = tsi_start (TREE_OPERAND (*stmt_p, 1));
1632 stmt = tsi_stmt (i);
1633 data->last_goto = NULL;
1635 switch (TREE_CODE (stmt))
1638 for (; !tsi_end_p (i); tsi_next (&i))
1640 stmt = tsi_stmt (i);
1641 /* If we catch all exceptions, then the body does not
1642 propagate exceptions past this point. */
1643 if (CATCH_TYPES (stmt) == NULL)
1644 this_may_throw = false;
1645 data->last_goto = NULL;
1646 remove_useless_stmts_1 (&CATCH_BODY (stmt), data);
1650 case EH_FILTER_EXPR:
1651 if (EH_FILTER_MUST_NOT_THROW (stmt))
1652 this_may_throw = false;
1653 else if (EH_FILTER_TYPES (stmt) == NULL)
1654 this_may_throw = false;
1655 remove_useless_stmts_1 (&EH_FILTER_FAILURE (stmt), data);
1659 /* Otherwise this is a cleanup. */
1660 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 1), data);
1662 /* If the cleanup is empty, then we can emit the TRY block without
1663 the enclosing TRY_CATCH_EXPR. */
1664 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 1)))
1666 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1667 data->repeat = true;
1671 data->may_throw |= this_may_throw;
1676 remove_useless_stmts_bind (tree *stmt_p, struct rus_data *data)
1680 /* First remove anything underneath the BIND_EXPR. */
1681 remove_useless_stmts_1 (&BIND_EXPR_BODY (*stmt_p), data);
1683 /* If the BIND_EXPR has no variables, then we can pull everything
1684 up one level and remove the BIND_EXPR, unless this is the toplevel
1685 BIND_EXPR for the current function or an inlined function.
1687 When this situation occurs we will want to apply this
1688 optimization again. */
1689 block = BIND_EXPR_BLOCK (*stmt_p);
1690 if (BIND_EXPR_VARS (*stmt_p) == NULL_TREE
1691 && *stmt_p != DECL_SAVED_TREE (current_function_decl)
1693 || ! BLOCK_ABSTRACT_ORIGIN (block)
1694 || (TREE_CODE (BLOCK_ABSTRACT_ORIGIN (block))
1697 *stmt_p = BIND_EXPR_BODY (*stmt_p);
1698 data->repeat = true;
1704 remove_useless_stmts_goto (tree *stmt_p, struct rus_data *data)
1706 tree dest = GOTO_DESTINATION (*stmt_p);
1708 data->may_branch = true;
1709 data->last_goto = NULL;
1711 /* Record the last goto expr, so that we can delete it if unnecessary. */
1712 if (TREE_CODE (dest) == LABEL_DECL)
1713 data->last_goto = stmt_p;
1718 remove_useless_stmts_label (tree *stmt_p, struct rus_data *data)
1720 tree label = LABEL_EXPR_LABEL (*stmt_p);
1722 data->has_label = true;
1724 /* We do want to jump across non-local label receiver code. */
1725 if (DECL_NONLOCAL (label))
1726 data->last_goto = NULL;
1728 else if (data->last_goto && GOTO_DESTINATION (*data->last_goto) == label)
1730 *data->last_goto = build_empty_stmt ();
1731 data->repeat = true;
1734 /* ??? Add something here to delete unused labels. */
1738 /* If the function is "const" or "pure", then clear TREE_SIDE_EFFECTS on its
1739 decl. This allows us to eliminate redundant or useless
1740 calls to "const" functions.
1742 Gimplifier already does the same operation, but we may notice functions
1743 being const and pure once their calls has been gimplified, so we need
1744 to update the flag. */
1747 update_call_expr_flags (tree call)
1749 tree decl = get_callee_fndecl (call);
1752 if (call_expr_flags (call) & (ECF_CONST | ECF_PURE))
1753 TREE_SIDE_EFFECTS (call) = 0;
1754 if (TREE_NOTHROW (decl))
1755 TREE_NOTHROW (call) = 1;
1759 /* T is CALL_EXPR. Set current_function_calls_* flags. */
1762 notice_special_calls (tree t)
1764 int flags = call_expr_flags (t);
1766 if (flags & ECF_MAY_BE_ALLOCA)
1767 current_function_calls_alloca = true;
1768 if (flags & ECF_RETURNS_TWICE)
1769 current_function_calls_setjmp = true;
1773 /* Clear flags set by notice_special_calls. Used by dead code removal
1774 to update the flags. */
1777 clear_special_calls (void)
1779 current_function_calls_alloca = false;
1780 current_function_calls_setjmp = false;
1785 remove_useless_stmts_1 (tree *tp, struct rus_data *data)
1789 switch (TREE_CODE (t))
1792 remove_useless_stmts_cond (tp, data);
1795 case TRY_FINALLY_EXPR:
1796 remove_useless_stmts_tf (tp, data);
1799 case TRY_CATCH_EXPR:
1800 remove_useless_stmts_tc (tp, data);
1804 remove_useless_stmts_bind (tp, data);
1808 remove_useless_stmts_goto (tp, data);
1812 remove_useless_stmts_label (tp, data);
1817 data->last_goto = NULL;
1818 data->may_branch = true;
1823 data->last_goto = NULL;
1824 notice_special_calls (t);
1825 update_call_expr_flags (t);
1826 if (tree_could_throw_p (t))
1827 data->may_throw = true;
1831 data->last_goto = NULL;
1833 op = get_call_expr_in (t);
1836 update_call_expr_flags (op);
1837 notice_special_calls (op);
1839 if (tree_could_throw_p (t))
1840 data->may_throw = true;
1843 case STATEMENT_LIST:
1845 tree_stmt_iterator i = tsi_start (t);
1846 while (!tsi_end_p (i))
1849 if (IS_EMPTY_STMT (t))
1855 remove_useless_stmts_1 (tsi_stmt_ptr (i), data);
1858 if (TREE_CODE (t) == STATEMENT_LIST)
1860 tsi_link_before (&i, t, TSI_SAME_STMT);
1870 data->last_goto = NULL;
1874 data->last_goto = NULL;
1880 remove_useless_stmts (void)
1882 struct rus_data data;
1884 clear_special_calls ();
1888 memset (&data, 0, sizeof (data));
1889 remove_useless_stmts_1 (&DECL_SAVED_TREE (current_function_decl), &data);
1891 while (data.repeat);
1895 struct tree_opt_pass pass_remove_useless_stmts =
1897 "useless", /* name */
1899 remove_useless_stmts, /* execute */
1902 0, /* static_pass_number */
1904 PROP_gimple_any, /* properties_required */
1905 0, /* properties_provided */
1906 0, /* properties_destroyed */
1907 0, /* todo_flags_start */
1908 TODO_dump_func, /* todo_flags_finish */
1913 /* Remove obviously useless statements in basic block BB. */
1916 cfg_remove_useless_stmts_bb (basic_block bb)
1918 block_stmt_iterator bsi;
1919 tree stmt = NULL_TREE;
1920 tree cond, var = NULL_TREE, val = NULL_TREE;
1921 struct var_ann_d *ann;
1923 /* Check whether we come here from a condition, and if so, get the
1925 if (EDGE_COUNT (bb->preds) != 1
1926 || !(EDGE_PRED (bb, 0)->flags & (EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
1929 cond = COND_EXPR_COND (last_stmt (EDGE_PRED (bb, 0)->src));
1931 if (TREE_CODE (cond) == VAR_DECL || TREE_CODE (cond) == PARM_DECL)
1934 val = (EDGE_PRED (bb, 0)->flags & EDGE_FALSE_VALUE
1935 ? boolean_false_node : boolean_true_node);
1937 else if (TREE_CODE (cond) == TRUTH_NOT_EXPR
1938 && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL
1939 || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL))
1941 var = TREE_OPERAND (cond, 0);
1942 val = (EDGE_PRED (bb, 0)->flags & EDGE_FALSE_VALUE
1943 ? boolean_true_node : boolean_false_node);
1947 if (EDGE_PRED (bb, 0)->flags & EDGE_FALSE_VALUE)
1948 cond = invert_truthvalue (cond);
1949 if (TREE_CODE (cond) == EQ_EXPR
1950 && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL
1951 || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL)
1952 && (TREE_CODE (TREE_OPERAND (cond, 1)) == VAR_DECL
1953 || TREE_CODE (TREE_OPERAND (cond, 1)) == PARM_DECL
1954 || TREE_CONSTANT (TREE_OPERAND (cond, 1))))
1956 var = TREE_OPERAND (cond, 0);
1957 val = TREE_OPERAND (cond, 1);
1963 /* Only work for normal local variables. */
1964 ann = var_ann (var);
1967 || TREE_ADDRESSABLE (var))
1970 if (! TREE_CONSTANT (val))
1972 ann = var_ann (val);
1975 || TREE_ADDRESSABLE (val))
1979 /* Ignore floating point variables, since comparison behaves weird for
1981 if (FLOAT_TYPE_P (TREE_TYPE (var)))
1984 for (bsi = bsi_start (bb); !bsi_end_p (bsi);)
1986 stmt = bsi_stmt (bsi);
1988 /* If the THEN/ELSE clause merely assigns a value to a variable/parameter
1989 which is already known to contain that value, then remove the useless
1990 THEN/ELSE clause. */
1991 if (TREE_CODE (stmt) == MODIFY_EXPR
1992 && TREE_OPERAND (stmt, 0) == var
1993 && operand_equal_p (val, TREE_OPERAND (stmt, 1), 0))
1999 /* Invalidate the var if we encounter something that could modify it.
2000 Likewise for the value it was previously set to. Note that we only
2001 consider values that are either a VAR_DECL or PARM_DECL so we
2002 can test for conflict very simply. */
2003 if (TREE_CODE (stmt) == ASM_EXPR
2004 || (TREE_CODE (stmt) == MODIFY_EXPR
2005 && (TREE_OPERAND (stmt, 0) == var
2006 || TREE_OPERAND (stmt, 0) == val)))
2014 /* A CFG-aware version of remove_useless_stmts. */
2017 cfg_remove_useless_stmts (void)
2021 #ifdef ENABLE_CHECKING
2022 verify_flow_info ();
2027 cfg_remove_useless_stmts_bb (bb);
2032 /* Remove PHI nodes associated with basic block BB and all edges out of BB. */
2035 remove_phi_nodes_and_edges_for_unreachable_block (basic_block bb)
2039 /* Since this block is no longer reachable, we can just delete all
2040 of its PHI nodes. */
2041 phi = phi_nodes (bb);
2044 tree next = PHI_CHAIN (phi);
2045 remove_phi_node (phi, NULL_TREE);
2049 /* Remove edges to BB's successors. */
2050 while (EDGE_COUNT (bb->succs) > 0)
2051 remove_edge (EDGE_SUCC (bb, 0));
2055 /* Remove statements of basic block BB. */
2058 remove_bb (basic_block bb)
2060 block_stmt_iterator i;
2061 #ifdef USE_MAPPED_LOCATION
2062 source_location loc = UNKNOWN_LOCATION;
2064 source_locus loc = 0;
2069 fprintf (dump_file, "Removing basic block %d\n", bb->index);
2070 if (dump_flags & TDF_DETAILS)
2072 dump_bb (bb, dump_file, 0);
2073 fprintf (dump_file, "\n");
2077 /* If we remove the header or the latch of a loop, mark the loop for
2078 removal by setting its header and latch to NULL. */
2081 struct loop *loop = bb->loop_father;
2083 if (loop->latch == bb
2084 || loop->header == bb)
2087 loop->header = NULL;
2091 /* Remove all the instructions in the block. */
2092 for (i = bsi_start (bb); !bsi_end_p (i);)
2094 tree stmt = bsi_stmt (i);
2095 if (TREE_CODE (stmt) == LABEL_EXPR
2096 && FORCED_LABEL (LABEL_EXPR_LABEL (stmt)))
2098 basic_block new_bb = bb->prev_bb;
2099 block_stmt_iterator new_bsi = bsi_start (new_bb);
2102 bsi_insert_before (&new_bsi, stmt, BSI_NEW_STMT);
2106 release_defs (stmt);
2108 set_bb_for_stmt (stmt, NULL);
2112 /* Don't warn for removed gotos. Gotos are often removed due to
2113 jump threading, thus resulting in bogus warnings. Not great,
2114 since this way we lose warnings for gotos in the original
2115 program that are indeed unreachable. */
2116 if (TREE_CODE (stmt) != GOTO_EXPR && EXPR_HAS_LOCATION (stmt) && !loc)
2118 #ifdef USE_MAPPED_LOCATION
2119 if (EXPR_HAS_LOCATION (stmt))
2120 loc = EXPR_LOCATION (stmt);
2123 t = EXPR_LOCUS (stmt);
2124 if (t && LOCATION_LINE (*t) > 0)
2130 /* If requested, give a warning that the first statement in the
2131 block is unreachable. We walk statements backwards in the
2132 loop above, so the last statement we process is the first statement
2134 #ifdef USE_MAPPED_LOCATION
2135 if (warn_notreached && loc != UNKNOWN_LOCATION)
2136 warning ("%Hwill never be executed", &loc);
2138 if (warn_notreached && loc)
2139 warning ("%Hwill never be executed", loc);
2142 remove_phi_nodes_and_edges_for_unreachable_block (bb);
2145 /* A list of all the noreturn calls passed to modify_stmt.
2146 cleanup_control_flow uses it to detect cases where a mid-block
2147 indirect call has been turned into a noreturn call. When this
2148 happens, all the instructions after the call are no longer
2149 reachable and must be deleted as dead. */
2151 VEC(tree) *modified_noreturn_calls;
2153 /* Try to remove superfluous control structures. */
2156 cleanup_control_flow (void)
2159 block_stmt_iterator bsi;
2160 bool retval = false;
2163 /* Detect cases where a mid-block call is now known not to return. */
2164 while (VEC_length (tree, modified_noreturn_calls))
2166 stmt = VEC_pop (tree, modified_noreturn_calls);
2167 bb = bb_for_stmt (stmt);
2168 if (bb != NULL && last_stmt (bb) != stmt && noreturn_call_p (stmt))
2169 split_block (bb, stmt);
2174 bsi = bsi_last (bb);
2176 if (bsi_end_p (bsi))
2179 stmt = bsi_stmt (bsi);
2180 if (TREE_CODE (stmt) == COND_EXPR
2181 || TREE_CODE (stmt) == SWITCH_EXPR)
2182 retval |= cleanup_control_expr_graph (bb, bsi);
2184 /* If we had a computed goto which has a compile-time determinable
2185 destination, then we can eliminate the goto. */
2186 if (TREE_CODE (stmt) == GOTO_EXPR
2187 && TREE_CODE (GOTO_DESTINATION (stmt)) == ADDR_EXPR
2188 && TREE_CODE (TREE_OPERAND (GOTO_DESTINATION (stmt), 0)) == LABEL_DECL)
2193 basic_block target_block;
2194 bool removed_edge = false;
2196 /* First look at all the outgoing edges. Delete any outgoing
2197 edges which do not go to the right block. For the one
2198 edge which goes to the right block, fix up its flags. */
2199 label = TREE_OPERAND (GOTO_DESTINATION (stmt), 0);
2200 target_block = label_to_block (label);
2201 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2203 if (e->dest != target_block)
2205 removed_edge = true;
2210 /* Turn off the EDGE_ABNORMAL flag. */
2211 EDGE_SUCC (bb, 0)->flags &= ~EDGE_ABNORMAL;
2213 /* And set EDGE_FALLTHRU. */
2214 EDGE_SUCC (bb, 0)->flags |= EDGE_FALLTHRU;
2219 /* If we removed one or more edges, then we will need to fix the
2220 dominators. It may be possible to incrementally update them. */
2222 free_dominance_info (CDI_DOMINATORS);
2224 /* Remove the GOTO_EXPR as it is not needed. The CFG has all the
2225 relevant information we need. */
2230 /* Check for indirect calls that have been turned into
2232 if (noreturn_call_p (stmt) && remove_fallthru_edge (bb->succs))
2234 free_dominance_info (CDI_DOMINATORS);
2242 /* Disconnect an unreachable block in the control expression starting
2246 cleanup_control_expr_graph (basic_block bb, block_stmt_iterator bsi)
2249 bool retval = false;
2250 tree expr = bsi_stmt (bsi), val;
2252 if (EDGE_COUNT (bb->succs) > 1)
2257 switch (TREE_CODE (expr))
2260 val = COND_EXPR_COND (expr);
2264 val = SWITCH_COND (expr);
2265 if (TREE_CODE (val) != INTEGER_CST)
2273 taken_edge = find_taken_edge (bb, val);
2277 /* Remove all the edges except the one that is always executed. */
2278 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2280 if (e != taken_edge)
2282 taken_edge->probability += e->probability;
2283 taken_edge->count += e->count;
2290 if (taken_edge->probability > REG_BR_PROB_BASE)
2291 taken_edge->probability = REG_BR_PROB_BASE;
2294 taken_edge = EDGE_SUCC (bb, 0);
2297 taken_edge->flags = EDGE_FALLTHRU;
2299 /* We removed some paths from the cfg. */
2300 free_dominance_info (CDI_DOMINATORS);
2305 /* Remove any fallthru edge from EV. Return true if an edge was removed. */
2308 remove_fallthru_edge (VEC(edge) *ev)
2313 FOR_EACH_EDGE (e, ei, ev)
2314 if ((e->flags & EDGE_FALLTHRU) != 0)
2322 /* Given a basic block BB ending with COND_EXPR or SWITCH_EXPR, and a
2323 predicate VAL, return the edge that will be taken out of the block.
2324 If VAL does not match a unique edge, NULL is returned. */
2327 find_taken_edge (basic_block bb, tree val)
2331 stmt = last_stmt (bb);
2334 gcc_assert (is_ctrl_stmt (stmt));
2337 if (! is_gimple_min_invariant (val))
2340 if (TREE_CODE (stmt) == COND_EXPR)
2341 return find_taken_edge_cond_expr (bb, val);
2343 if (TREE_CODE (stmt) == SWITCH_EXPR)
2344 return find_taken_edge_switch_expr (bb, val);
2346 if (computed_goto_p (stmt))
2347 return find_taken_edge_computed_goto (bb, TREE_OPERAND( val, 0));
2352 /* Given a constant value VAL and the entry block BB to a GOTO_EXPR
2353 statement, determine which of the outgoing edges will be taken out of the
2354 block. Return NULL if either edge may be taken. */
2357 find_taken_edge_computed_goto (basic_block bb, tree val)
2362 dest = label_to_block (val);
2365 e = find_edge (bb, dest);
2366 gcc_assert (e != NULL);
2372 /* Given a constant value VAL and the entry block BB to a COND_EXPR
2373 statement, determine which of the two edges will be taken out of the
2374 block. Return NULL if either edge may be taken. */
2377 find_taken_edge_cond_expr (basic_block bb, tree val)
2379 edge true_edge, false_edge;
2381 extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
2383 /* Otherwise, try to determine which branch of the if() will be taken.
2384 If VAL is a constant but it can't be reduced to a 0 or a 1, then
2385 we don't really know which edge will be taken at runtime. This
2386 may happen when comparing addresses (e.g., if (&var1 == 4)). */
2387 if (integer_nonzerop (val))
2389 else if (integer_zerop (val))
2396 /* Given an INTEGER_CST VAL and the entry block BB to a SWITCH_EXPR
2397 statement, determine which edge will be taken out of the block. Return
2398 NULL if any edge may be taken. */
2401 find_taken_edge_switch_expr (basic_block bb, tree val)
2403 tree switch_expr, taken_case;
2404 basic_block dest_bb;
2407 switch_expr = last_stmt (bb);
2408 taken_case = find_case_label_for_value (switch_expr, val);
2409 dest_bb = label_to_block (CASE_LABEL (taken_case));
2411 e = find_edge (bb, dest_bb);
2417 /* Return the CASE_LABEL_EXPR that SWITCH_EXPR will take for VAL.
2418 We can make optimal use here of the fact that the case labels are
2419 sorted: We can do a binary search for a case matching VAL. */
2422 find_case_label_for_value (tree switch_expr, tree val)
2424 tree vec = SWITCH_LABELS (switch_expr);
2425 size_t low, high, n = TREE_VEC_LENGTH (vec);
2426 tree default_case = TREE_VEC_ELT (vec, n - 1);
2428 for (low = -1, high = n - 1; high - low > 1; )
2430 size_t i = (high + low) / 2;
2431 tree t = TREE_VEC_ELT (vec, i);
2434 /* Cache the result of comparing CASE_LOW and val. */
2435 cmp = tree_int_cst_compare (CASE_LOW (t), val);
2442 if (CASE_HIGH (t) == NULL)
2444 /* A singe-valued case label. */
2450 /* A case range. We can only handle integer ranges. */
2451 if (cmp <= 0 && tree_int_cst_compare (CASE_HIGH (t), val) >= 0)
2456 return default_case;
2460 /* If all the PHI nodes in DEST have alternatives for E1 and E2 and
2461 those alternatives are equal in each of the PHI nodes, then return
2462 true, else return false. */
2465 phi_alternatives_equal (basic_block dest, edge e1, edge e2)
2467 int n1 = e1->dest_idx;
2468 int n2 = e2->dest_idx;
2471 for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi))
2473 tree val1 = PHI_ARG_DEF (phi, n1);
2474 tree val2 = PHI_ARG_DEF (phi, n2);
2476 gcc_assert (val1 != NULL_TREE);
2477 gcc_assert (val2 != NULL_TREE);
2479 if (!operand_equal_for_phi_arg_p (val1, val2))
2487 /*---------------------------------------------------------------------------
2489 ---------------------------------------------------------------------------*/
2491 /* Dump tree-specific information of block BB to file OUTF. */
2494 tree_dump_bb (basic_block bb, FILE *outf, int indent)
2496 dump_generic_bb (outf, bb, indent, TDF_VOPS);
2500 /* Dump a basic block on stderr. */
2503 debug_tree_bb (basic_block bb)
2505 dump_bb (bb, stderr, 0);
2509 /* Dump basic block with index N on stderr. */
2512 debug_tree_bb_n (int n)
2514 debug_tree_bb (BASIC_BLOCK (n));
2515 return BASIC_BLOCK (n);
2519 /* Dump the CFG on stderr.
2521 FLAGS are the same used by the tree dumping functions
2522 (see TDF_* in tree.h). */
2525 debug_tree_cfg (int flags)
2527 dump_tree_cfg (stderr, flags);
2531 /* Dump the program showing basic block boundaries on the given FILE.
2533 FLAGS are the same used by the tree dumping functions (see TDF_* in
2537 dump_tree_cfg (FILE *file, int flags)
2539 if (flags & TDF_DETAILS)
2541 const char *funcname
2542 = lang_hooks.decl_printable_name (current_function_decl, 2);
2545 fprintf (file, ";; Function %s\n\n", funcname);
2546 fprintf (file, ";; \n%d basic blocks, %d edges, last basic block %d.\n\n",
2547 n_basic_blocks, n_edges, last_basic_block);
2549 brief_dump_cfg (file);
2550 fprintf (file, "\n");
2553 if (flags & TDF_STATS)
2554 dump_cfg_stats (file);
2556 dump_function_to_file (current_function_decl, file, flags | TDF_BLOCKS);
2560 /* Dump CFG statistics on FILE. */
2563 dump_cfg_stats (FILE *file)
2565 static long max_num_merged_labels = 0;
2566 unsigned long size, total = 0;
2569 const char * const fmt_str = "%-30s%-13s%12s\n";
2570 const char * const fmt_str_1 = "%-30s%13d%11lu%c\n";
2571 const char * const fmt_str_3 = "%-43s%11lu%c\n";
2572 const char *funcname
2573 = lang_hooks.decl_printable_name (current_function_decl, 2);
2576 fprintf (file, "\nCFG Statistics for %s\n\n", funcname);
2578 fprintf (file, "---------------------------------------------------------\n");
2579 fprintf (file, fmt_str, "", " Number of ", "Memory");
2580 fprintf (file, fmt_str, "", " instances ", "used ");
2581 fprintf (file, "---------------------------------------------------------\n");
2583 size = n_basic_blocks * sizeof (struct basic_block_def);
2585 fprintf (file, fmt_str_1, "Basic blocks", n_basic_blocks,
2586 SCALE (size), LABEL (size));
2590 n_edges += EDGE_COUNT (bb->succs);
2591 size = n_edges * sizeof (struct edge_def);
2593 fprintf (file, fmt_str_1, "Edges", n_edges, SCALE (size), LABEL (size));
2595 size = n_basic_blocks * sizeof (struct bb_ann_d);
2597 fprintf (file, fmt_str_1, "Basic block annotations", n_basic_blocks,
2598 SCALE (size), LABEL (size));
2600 fprintf (file, "---------------------------------------------------------\n");
2601 fprintf (file, fmt_str_3, "Total memory used by CFG data", SCALE (total),
2603 fprintf (file, "---------------------------------------------------------\n");
2604 fprintf (file, "\n");
2606 if (cfg_stats.num_merged_labels > max_num_merged_labels)
2607 max_num_merged_labels = cfg_stats.num_merged_labels;
2609 fprintf (file, "Coalesced label blocks: %ld (Max so far: %ld)\n",
2610 cfg_stats.num_merged_labels, max_num_merged_labels);
2612 fprintf (file, "\n");
2616 /* Dump CFG statistics on stderr. Keep extern so that it's always
2617 linked in the final executable. */
2620 debug_cfg_stats (void)
2622 dump_cfg_stats (stderr);
2626 /* Dump the flowgraph to a .vcg FILE. */
2629 tree_cfg2vcg (FILE *file)
2634 const char *funcname
2635 = lang_hooks.decl_printable_name (current_function_decl, 2);
2637 /* Write the file header. */
2638 fprintf (file, "graph: { title: \"%s\"\n", funcname);
2639 fprintf (file, "node: { title: \"ENTRY\" label: \"ENTRY\" }\n");
2640 fprintf (file, "node: { title: \"EXIT\" label: \"EXIT\" }\n");
2642 /* Write blocks and edges. */
2643 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
2645 fprintf (file, "edge: { sourcename: \"ENTRY\" targetname: \"%d\"",
2648 if (e->flags & EDGE_FAKE)
2649 fprintf (file, " linestyle: dotted priority: 10");
2651 fprintf (file, " linestyle: solid priority: 100");
2653 fprintf (file, " }\n");
2659 enum tree_code head_code, end_code;
2660 const char *head_name, *end_name;
2663 tree first = first_stmt (bb);
2664 tree last = last_stmt (bb);
2668 head_code = TREE_CODE (first);
2669 head_name = tree_code_name[head_code];
2670 head_line = get_lineno (first);
2673 head_name = "no-statement";
2677 end_code = TREE_CODE (last);
2678 end_name = tree_code_name[end_code];
2679 end_line = get_lineno (last);
2682 end_name = "no-statement";
2684 fprintf (file, "node: { title: \"%d\" label: \"#%d\\n%s (%d)\\n%s (%d)\"}\n",
2685 bb->index, bb->index, head_name, head_line, end_name,
2688 FOR_EACH_EDGE (e, ei, bb->succs)
2690 if (e->dest == EXIT_BLOCK_PTR)
2691 fprintf (file, "edge: { sourcename: \"%d\" targetname: \"EXIT\"", bb->index);
2693 fprintf (file, "edge: { sourcename: \"%d\" targetname: \"%d\"", bb->index, e->dest->index);
2695 if (e->flags & EDGE_FAKE)
2696 fprintf (file, " priority: 10 linestyle: dotted");
2698 fprintf (file, " priority: 100 linestyle: solid");
2700 fprintf (file, " }\n");
2703 if (bb->next_bb != EXIT_BLOCK_PTR)
2707 fputs ("}\n\n", file);
2712 /*---------------------------------------------------------------------------
2713 Miscellaneous helpers
2714 ---------------------------------------------------------------------------*/
2716 /* Return true if T represents a stmt that always transfers control. */
2719 is_ctrl_stmt (tree t)
2721 return (TREE_CODE (t) == COND_EXPR
2722 || TREE_CODE (t) == SWITCH_EXPR
2723 || TREE_CODE (t) == GOTO_EXPR
2724 || TREE_CODE (t) == RETURN_EXPR
2725 || TREE_CODE (t) == RESX_EXPR);
2729 /* Return true if T is a statement that may alter the flow of control
2730 (e.g., a call to a non-returning function). */
2733 is_ctrl_altering_stmt (tree t)
2738 call = get_call_expr_in (t);
2741 /* A non-pure/const CALL_EXPR alters flow control if the current
2742 function has nonlocal labels. */
2743 if (TREE_SIDE_EFFECTS (call) && current_function_has_nonlocal_label)
2746 /* A CALL_EXPR also alters control flow if it does not return. */
2747 if (call_expr_flags (call) & ECF_NORETURN)
2751 /* If a statement can throw, it alters control flow. */
2752 return tree_can_throw_internal (t);
2756 /* Return true if T is a computed goto. */
2759 computed_goto_p (tree t)
2761 return (TREE_CODE (t) == GOTO_EXPR
2762 && TREE_CODE (GOTO_DESTINATION (t)) != LABEL_DECL);
2766 /* Checks whether EXPR is a simple local goto. */
2769 simple_goto_p (tree expr)
2771 return (TREE_CODE (expr) == GOTO_EXPR
2772 && TREE_CODE (GOTO_DESTINATION (expr)) == LABEL_DECL);
2776 /* Return true if T should start a new basic block. PREV_T is the
2777 statement preceding T. It is used when T is a label or a case label.
2778 Labels should only start a new basic block if their previous statement
2779 wasn't a label. Otherwise, sequence of labels would generate
2780 unnecessary basic blocks that only contain a single label. */
2783 stmt_starts_bb_p (tree t, tree prev_t)
2788 /* LABEL_EXPRs start a new basic block only if the preceding
2789 statement wasn't a label of the same type. This prevents the
2790 creation of consecutive blocks that have nothing but a single
2792 if (TREE_CODE (t) == LABEL_EXPR)
2794 /* Nonlocal and computed GOTO targets always start a new block. */
2795 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (t))
2796 || FORCED_LABEL (LABEL_EXPR_LABEL (t)))
2799 if (prev_t && TREE_CODE (prev_t) == LABEL_EXPR)
2801 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (prev_t)))
2804 cfg_stats.num_merged_labels++;
2815 /* Return true if T should end a basic block. */
2818 stmt_ends_bb_p (tree t)
2820 return is_ctrl_stmt (t) || is_ctrl_altering_stmt (t);
2824 /* Add gotos that used to be represented implicitly in the CFG. */
2827 disband_implicit_edges (void)
2830 block_stmt_iterator last;
2837 last = bsi_last (bb);
2838 stmt = last_stmt (bb);
2840 if (stmt && TREE_CODE (stmt) == COND_EXPR)
2842 /* Remove superfluous gotos from COND_EXPR branches. Moved
2843 from cfg_remove_useless_stmts here since it violates the
2844 invariants for tree--cfg correspondence and thus fits better
2845 here where we do it anyway. */
2846 e = find_edge (bb, bb->next_bb);
2849 if (e->flags & EDGE_TRUE_VALUE)
2850 COND_EXPR_THEN (stmt) = build_empty_stmt ();
2851 else if (e->flags & EDGE_FALSE_VALUE)
2852 COND_EXPR_ELSE (stmt) = build_empty_stmt ();
2855 e->flags |= EDGE_FALLTHRU;
2861 if (stmt && TREE_CODE (stmt) == RETURN_EXPR)
2863 /* Remove the RETURN_EXPR if we may fall though to the exit
2865 gcc_assert (EDGE_COUNT (bb->succs) == 1);
2866 gcc_assert (EDGE_SUCC (bb, 0)->dest == EXIT_BLOCK_PTR);
2868 if (bb->next_bb == EXIT_BLOCK_PTR
2869 && !TREE_OPERAND (stmt, 0))
2872 EDGE_SUCC (bb, 0)->flags |= EDGE_FALLTHRU;
2877 /* There can be no fallthru edge if the last statement is a control
2879 if (stmt && is_ctrl_stmt (stmt))
2882 /* Find a fallthru edge and emit the goto if necessary. */
2883 FOR_EACH_EDGE (e, ei, bb->succs)
2884 if (e->flags & EDGE_FALLTHRU)
2887 if (!e || e->dest == bb->next_bb)
2890 gcc_assert (e->dest != EXIT_BLOCK_PTR);
2891 label = tree_block_label (e->dest);
2893 stmt = build1 (GOTO_EXPR, void_type_node, label);
2894 #ifdef USE_MAPPED_LOCATION
2895 SET_EXPR_LOCATION (stmt, e->goto_locus);
2897 SET_EXPR_LOCUS (stmt, e->goto_locus);
2899 bsi_insert_after (&last, stmt, BSI_NEW_STMT);
2900 e->flags &= ~EDGE_FALLTHRU;
2904 /* Remove block annotations and other datastructures. */
2907 delete_tree_cfg_annotations (void)
2910 if (n_basic_blocks > 0)
2911 free_blocks_annotations ();
2913 label_to_block_map = NULL;
2920 /* Return the first statement in basic block BB. */
2923 first_stmt (basic_block bb)
2925 block_stmt_iterator i = bsi_start (bb);
2926 return !bsi_end_p (i) ? bsi_stmt (i) : NULL_TREE;
2930 /* Return the last statement in basic block BB. */
2933 last_stmt (basic_block bb)
2935 block_stmt_iterator b = bsi_last (bb);
2936 return !bsi_end_p (b) ? bsi_stmt (b) : NULL_TREE;
2940 /* Return a pointer to the last statement in block BB. */
2943 last_stmt_ptr (basic_block bb)
2945 block_stmt_iterator last = bsi_last (bb);
2946 return !bsi_end_p (last) ? bsi_stmt_ptr (last) : NULL;
2950 /* Return the last statement of an otherwise empty block. Return NULL
2951 if the block is totally empty, or if it contains more than one
2955 last_and_only_stmt (basic_block bb)
2957 block_stmt_iterator i = bsi_last (bb);
2963 last = bsi_stmt (i);
2968 /* Empty statements should no longer appear in the instruction stream.
2969 Everything that might have appeared before should be deleted by
2970 remove_useless_stmts, and the optimizers should just bsi_remove
2971 instead of smashing with build_empty_stmt.
2973 Thus the only thing that should appear here in a block containing
2974 one executable statement is a label. */
2975 prev = bsi_stmt (i);
2976 if (TREE_CODE (prev) == LABEL_EXPR)
2983 /* Mark BB as the basic block holding statement T. */
2986 set_bb_for_stmt (tree t, basic_block bb)
2988 if (TREE_CODE (t) == PHI_NODE)
2990 else if (TREE_CODE (t) == STATEMENT_LIST)
2992 tree_stmt_iterator i;
2993 for (i = tsi_start (t); !tsi_end_p (i); tsi_next (&i))
2994 set_bb_for_stmt (tsi_stmt (i), bb);
2998 stmt_ann_t ann = get_stmt_ann (t);
3001 /* If the statement is a label, add the label to block-to-labels map
3002 so that we can speed up edge creation for GOTO_EXPRs. */
3003 if (TREE_CODE (t) == LABEL_EXPR)
3007 t = LABEL_EXPR_LABEL (t);
3008 uid = LABEL_DECL_UID (t);
3011 LABEL_DECL_UID (t) = uid = cfun->last_label_uid++;
3012 if (VARRAY_SIZE (label_to_block_map) <= (unsigned) uid)
3013 VARRAY_GROW (label_to_block_map, 3 * uid / 2);
3016 /* We're moving an existing label. Make sure that we've
3017 removed it from the old block. */
3018 gcc_assert (!bb || !VARRAY_BB (label_to_block_map, uid));
3019 VARRAY_BB (label_to_block_map, uid) = bb;
3024 /* Finds iterator for STMT. */
3026 extern block_stmt_iterator
3027 bsi_for_stmt (tree stmt)
3029 block_stmt_iterator bsi;
3031 for (bsi = bsi_start (bb_for_stmt (stmt)); !bsi_end_p (bsi); bsi_next (&bsi))
3032 if (bsi_stmt (bsi) == stmt)
3038 /* Insert statement (or statement list) T before the statement
3039 pointed-to by iterator I. M specifies how to update iterator I
3040 after insertion (see enum bsi_iterator_update). */
3043 bsi_insert_before (block_stmt_iterator *i, tree t, enum bsi_iterator_update m)
3045 set_bb_for_stmt (t, i->bb);
3046 tsi_link_before (&i->tsi, t, m);
3051 /* Insert statement (or statement list) T after the statement
3052 pointed-to by iterator I. M specifies how to update iterator I
3053 after insertion (see enum bsi_iterator_update). */
3056 bsi_insert_after (block_stmt_iterator *i, tree t, enum bsi_iterator_update m)
3058 set_bb_for_stmt (t, i->bb);
3059 tsi_link_after (&i->tsi, t, m);
3064 /* Remove the statement pointed to by iterator I. The iterator is updated
3065 to the next statement. */
3068 bsi_remove (block_stmt_iterator *i)
3070 tree t = bsi_stmt (*i);
3071 set_bb_for_stmt (t, NULL);
3072 tsi_delink (&i->tsi);
3076 /* Move the statement at FROM so it comes right after the statement at TO. */
3079 bsi_move_after (block_stmt_iterator *from, block_stmt_iterator *to)
3081 tree stmt = bsi_stmt (*from);
3083 bsi_insert_after (to, stmt, BSI_SAME_STMT);
3087 /* Move the statement at FROM so it comes right before the statement at TO. */
3090 bsi_move_before (block_stmt_iterator *from, block_stmt_iterator *to)
3092 tree stmt = bsi_stmt (*from);
3094 bsi_insert_before (to, stmt, BSI_SAME_STMT);
3098 /* Move the statement at FROM to the end of basic block BB. */
3101 bsi_move_to_bb_end (block_stmt_iterator *from, basic_block bb)
3103 block_stmt_iterator last = bsi_last (bb);
3105 /* Have to check bsi_end_p because it could be an empty block. */
3106 if (!bsi_end_p (last) && is_ctrl_stmt (bsi_stmt (last)))
3107 bsi_move_before (from, &last);
3109 bsi_move_after (from, &last);
3113 /* Replace the contents of the statement pointed to by iterator BSI
3114 with STMT. If PRESERVE_EH_INFO is true, the exception handling
3115 information of the original statement is preserved. */
3118 bsi_replace (const block_stmt_iterator *bsi, tree stmt, bool preserve_eh_info)
3121 tree orig_stmt = bsi_stmt (*bsi);
3123 SET_EXPR_LOCUS (stmt, EXPR_LOCUS (orig_stmt));
3124 set_bb_for_stmt (stmt, bsi->bb);
3126 /* Preserve EH region information from the original statement, if
3127 requested by the caller. */
3128 if (preserve_eh_info)
3130 eh_region = lookup_stmt_eh_region (orig_stmt);
3132 add_stmt_to_eh_region (stmt, eh_region);
3135 *bsi_stmt_ptr (*bsi) = stmt;
3140 /* Insert the statement pointed-to by BSI into edge E. Every attempt
3141 is made to place the statement in an existing basic block, but
3142 sometimes that isn't possible. When it isn't possible, the edge is
3143 split and the statement is added to the new block.
3145 In all cases, the returned *BSI points to the correct location. The
3146 return value is true if insertion should be done after the location,
3147 or false if it should be done before the location. If new basic block
3148 has to be created, it is stored in *NEW_BB. */
3151 tree_find_edge_insert_loc (edge e, block_stmt_iterator *bsi,
3152 basic_block *new_bb)
3154 basic_block dest, src;
3160 /* If the destination has one predecessor which has no PHI nodes,
3161 insert there. Except for the exit block.
3163 The requirement for no PHI nodes could be relaxed. Basically we
3164 would have to examine the PHIs to prove that none of them used
3165 the value set by the statement we want to insert on E. That
3166 hardly seems worth the effort. */
3167 if (EDGE_COUNT (dest->preds) == 1
3168 && ! phi_nodes (dest)
3169 && dest != EXIT_BLOCK_PTR)
3171 *bsi = bsi_start (dest);
3172 if (bsi_end_p (*bsi))
3175 /* Make sure we insert after any leading labels. */
3176 tmp = bsi_stmt (*bsi);
3177 while (TREE_CODE (tmp) == LABEL_EXPR)
3180 if (bsi_end_p (*bsi))
3182 tmp = bsi_stmt (*bsi);
3185 if (bsi_end_p (*bsi))
3187 *bsi = bsi_last (dest);
3194 /* If the source has one successor, the edge is not abnormal and
3195 the last statement does not end a basic block, insert there.
3196 Except for the entry block. */
3198 if ((e->flags & EDGE_ABNORMAL) == 0
3199 && EDGE_COUNT (src->succs) == 1
3200 && src != ENTRY_BLOCK_PTR)
3202 *bsi = bsi_last (src);
3203 if (bsi_end_p (*bsi))
3206 tmp = bsi_stmt (*bsi);
3207 if (!stmt_ends_bb_p (tmp))
3210 /* Insert code just before returning the value. We may need to decompose
3211 the return in the case it contains non-trivial operand. */
3212 if (TREE_CODE (tmp) == RETURN_EXPR)
3214 tree op = TREE_OPERAND (tmp, 0);
3215 if (!is_gimple_val (op))
3217 gcc_assert (TREE_CODE (op) == MODIFY_EXPR);
3218 bsi_insert_before (bsi, op, BSI_NEW_STMT);
3219 TREE_OPERAND (tmp, 0) = TREE_OPERAND (op, 0);
3226 /* Otherwise, create a new basic block, and split this edge. */
3227 dest = split_edge (e);
3230 e = EDGE_PRED (dest, 0);
3235 /* This routine will commit all pending edge insertions, creating any new
3236 basic blocks which are necessary. */
3239 bsi_commit_edge_inserts (void)
3245 bsi_commit_one_edge_insert (EDGE_SUCC (ENTRY_BLOCK_PTR, 0), NULL);
3248 FOR_EACH_EDGE (e, ei, bb->succs)
3249 bsi_commit_one_edge_insert (e, NULL);
3253 /* Commit insertions pending at edge E. If a new block is created, set NEW_BB
3254 to this block, otherwise set it to NULL. */
3257 bsi_commit_one_edge_insert (edge e, basic_block *new_bb)
3261 if (PENDING_STMT (e))
3263 block_stmt_iterator bsi;
3264 tree stmt = PENDING_STMT (e);
3266 PENDING_STMT (e) = NULL_TREE;
3268 if (tree_find_edge_insert_loc (e, &bsi, new_bb))
3269 bsi_insert_after (&bsi, stmt, BSI_NEW_STMT);
3271 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
3276 /* Add STMT to the pending list of edge E. No actual insertion is
3277 made until a call to bsi_commit_edge_inserts () is made. */
3280 bsi_insert_on_edge (edge e, tree stmt)
3282 append_to_statement_list (stmt, &PENDING_STMT (e));
3285 /* Similar to bsi_insert_on_edge+bsi_commit_edge_inserts. If a new
3286 block has to be created, it is returned. */
3289 bsi_insert_on_edge_immediate (edge e, tree stmt)
3291 block_stmt_iterator bsi;
3292 basic_block new_bb = NULL;
3294 gcc_assert (!PENDING_STMT (e));
3296 if (tree_find_edge_insert_loc (e, &bsi, &new_bb))
3297 bsi_insert_after (&bsi, stmt, BSI_NEW_STMT);
3299 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
3304 /*---------------------------------------------------------------------------
3305 Tree specific functions for CFG manipulation
3306 ---------------------------------------------------------------------------*/
3308 /* Reinstall those PHI arguments queued in OLD_EDGE to NEW_EDGE. */
3311 reinstall_phi_args (edge new_edge, edge old_edge)
3315 if (!PENDING_STMT (old_edge))
3318 for (var = PENDING_STMT (old_edge), phi = phi_nodes (new_edge->dest);
3320 var = TREE_CHAIN (var), phi = PHI_CHAIN (phi))
3322 tree result = TREE_PURPOSE (var);
3323 tree arg = TREE_VALUE (var);
3325 gcc_assert (result == PHI_RESULT (phi));
3327 add_phi_arg (phi, arg, new_edge);
3330 PENDING_STMT (old_edge) = NULL;
3333 /* Split a (typically critical) edge EDGE_IN. Return the new block.
3334 Abort on abnormal edges. */
3337 tree_split_edge (edge edge_in)
3339 basic_block new_bb, after_bb, dest, src;
3342 /* Abnormal edges cannot be split. */
3343 gcc_assert (!(edge_in->flags & EDGE_ABNORMAL));
3346 dest = edge_in->dest;
3348 /* Place the new block in the block list. Try to keep the new block
3349 near its "logical" location. This is of most help to humans looking
3350 at debugging dumps. */
3351 if (dest->prev_bb && find_edge (dest->prev_bb, dest))
3352 after_bb = edge_in->src;
3354 after_bb = dest->prev_bb;
3356 new_bb = create_empty_bb (after_bb);
3357 new_bb->frequency = EDGE_FREQUENCY (edge_in);
3358 new_bb->count = edge_in->count;
3359 new_edge = make_edge (new_bb, dest, EDGE_FALLTHRU);
3360 new_edge->probability = REG_BR_PROB_BASE;
3361 new_edge->count = edge_in->count;
3363 e = redirect_edge_and_branch (edge_in, new_bb);
3365 reinstall_phi_args (new_edge, e);
3371 /* Return true when BB has label LABEL in it. */
3374 has_label_p (basic_block bb, tree label)
3376 block_stmt_iterator bsi;
3378 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3380 tree stmt = bsi_stmt (bsi);
3382 if (TREE_CODE (stmt) != LABEL_EXPR)
3384 if (LABEL_EXPR_LABEL (stmt) == label)
3391 /* Callback for walk_tree, check that all elements with address taken are
3392 properly noticed as such. The DATA is an int* that is 1 if TP was seen
3393 inside a PHI node. */
3396 verify_expr (tree *tp, int *walk_subtrees, void *data ATTRIBUTE_UNUSED)
3399 bool in_phi = (data != NULL);
3404 /* Check operand N for being valid GIMPLE and give error MSG if not.
3405 We check for constants explicitly since they are not considered
3406 gimple invariants if they overflowed. */
3407 #define CHECK_OP(N, MSG) \
3408 do { if (!CONSTANT_CLASS_P (TREE_OPERAND (t, N)) \
3409 && !is_gimple_val (TREE_OPERAND (t, N))) \
3410 { error (MSG); return TREE_OPERAND (t, N); }} while (0)
3412 switch (TREE_CODE (t))
3415 if (SSA_NAME_IN_FREE_LIST (t))
3417 error ("SSA name in freelist but still referenced");
3423 x = TREE_OPERAND (t, 0);
3424 if (TREE_CODE (x) == BIT_FIELD_REF
3425 && is_gimple_reg (TREE_OPERAND (x, 0)))
3427 error ("GIMPLE register modified with BIT_FIELD_REF");
3433 /* ??? tree-ssa-alias.c may have overlooked dead PHI nodes, missing
3434 dead PHIs that take the address of something. But if the PHI
3435 result is dead, the fact that it takes the address of anything
3436 is irrelevant. Because we can not tell from here if a PHI result
3437 is dead, we just skip this check for PHIs altogether. This means
3438 we may be missing "valid" checks, but what can you do?
3439 This was PR19217. */
3443 /* Skip any references (they will be checked when we recurse down the
3444 tree) and ensure that any variable used as a prefix is marked
3446 for (x = TREE_OPERAND (t, 0);
3447 handled_component_p (x);
3448 x = TREE_OPERAND (x, 0))
3451 if (TREE_CODE (x) != VAR_DECL && TREE_CODE (x) != PARM_DECL)
3453 if (!TREE_ADDRESSABLE (x))
3455 error ("address taken, but ADDRESSABLE bit not set");
3461 x = COND_EXPR_COND (t);
3462 if (TREE_CODE (TREE_TYPE (x)) != BOOLEAN_TYPE)
3464 error ("non-boolean used in condition");
3471 case FIX_TRUNC_EXPR:
3473 case FIX_FLOOR_EXPR:
3474 case FIX_ROUND_EXPR:
3479 case NON_LVALUE_EXPR:
3480 case TRUTH_NOT_EXPR:
3481 CHECK_OP (0, "Invalid operand to unary operator");
3488 case ARRAY_RANGE_REF:
3490 case VIEW_CONVERT_EXPR:
3491 /* We have a nest of references. Verify that each of the operands
3492 that determine where to reference is either a constant or a variable,
3493 verify that the base is valid, and then show we've already checked
3495 while (handled_component_p (t))
3497 if (TREE_CODE (t) == COMPONENT_REF && TREE_OPERAND (t, 2))
3498 CHECK_OP (2, "Invalid COMPONENT_REF offset operator");
3499 else if (TREE_CODE (t) == ARRAY_REF
3500 || TREE_CODE (t) == ARRAY_RANGE_REF)
3502 CHECK_OP (1, "Invalid array index.");
3503 if (TREE_OPERAND (t, 2))
3504 CHECK_OP (2, "Invalid array lower bound.");
3505 if (TREE_OPERAND (t, 3))
3506 CHECK_OP (3, "Invalid array stride.");
3508 else if (TREE_CODE (t) == BIT_FIELD_REF)
3510 CHECK_OP (1, "Invalid operand to BIT_FIELD_REF");
3511 CHECK_OP (2, "Invalid operand to BIT_FIELD_REF");
3514 t = TREE_OPERAND (t, 0);
3517 if (!CONSTANT_CLASS_P (t) && !is_gimple_lvalue (t))
3519 error ("Invalid reference prefix.");
3531 case UNORDERED_EXPR:
3542 case TRUNC_DIV_EXPR:
3544 case FLOOR_DIV_EXPR:
3545 case ROUND_DIV_EXPR:
3546 case TRUNC_MOD_EXPR:
3548 case FLOOR_MOD_EXPR:
3549 case ROUND_MOD_EXPR:
3551 case EXACT_DIV_EXPR:
3561 CHECK_OP (0, "Invalid operand to binary operator");
3562 CHECK_OP (1, "Invalid operand to binary operator");
3574 /* Verify STMT, return true if STMT is not in GIMPLE form.
3575 TODO: Implement type checking. */
3578 verify_stmt (tree stmt, bool last_in_block)
3582 if (!is_gimple_stmt (stmt))
3584 error ("Is not a valid GIMPLE statement.");
3588 addr = walk_tree (&stmt, verify_expr, NULL, NULL);
3591 debug_generic_stmt (addr);
3595 /* If the statement is marked as part of an EH region, then it is
3596 expected that the statement could throw. Verify that when we
3597 have optimizations that simplify statements such that we prove
3598 that they cannot throw, that we update other data structures
3600 if (lookup_stmt_eh_region (stmt) >= 0)
3602 if (!tree_could_throw_p (stmt))
3604 error ("Statement marked for throw, but doesn%'t.");
3607 if (!last_in_block && tree_can_throw_internal (stmt))
3609 error ("Statement marked for throw in middle of block.");
3617 debug_generic_stmt (stmt);
3622 /* Return true when the T can be shared. */
3625 tree_node_can_be_shared (tree t)
3627 if (IS_TYPE_OR_DECL_P (t)
3628 /* We check for constants explicitly since they are not considered
3629 gimple invariants if they overflowed. */
3630 || CONSTANT_CLASS_P (t)
3631 || is_gimple_min_invariant (t)
3632 || TREE_CODE (t) == SSA_NAME
3633 || t == error_mark_node)
3636 if (TREE_CODE (t) == CASE_LABEL_EXPR)
3639 while (((TREE_CODE (t) == ARRAY_REF || TREE_CODE (t) == ARRAY_RANGE_REF)
3640 /* We check for constants explicitly since they are not considered
3641 gimple invariants if they overflowed. */
3642 && (CONSTANT_CLASS_P (TREE_OPERAND (t, 1))
3643 || is_gimple_min_invariant (TREE_OPERAND (t, 1))))
3644 || (TREE_CODE (t) == COMPONENT_REF
3645 || TREE_CODE (t) == REALPART_EXPR
3646 || TREE_CODE (t) == IMAGPART_EXPR))
3647 t = TREE_OPERAND (t, 0);
3656 /* Called via walk_trees. Verify tree sharing. */
3659 verify_node_sharing (tree * tp, int *walk_subtrees, void *data)
3661 htab_t htab = (htab_t) data;
3664 if (tree_node_can_be_shared (*tp))
3666 *walk_subtrees = false;
3670 slot = htab_find_slot (htab, *tp, INSERT);
3679 /* Verify the GIMPLE statement chain. */
3685 block_stmt_iterator bsi;
3690 timevar_push (TV_TREE_STMT_VERIFY);
3691 htab = htab_create (37, htab_hash_pointer, htab_eq_pointer, NULL);
3698 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
3700 int phi_num_args = PHI_NUM_ARGS (phi);
3702 for (i = 0; i < phi_num_args; i++)
3704 tree t = PHI_ARG_DEF (phi, i);
3707 /* Addressable variables do have SSA_NAMEs but they
3708 are not considered gimple values. */
3709 if (TREE_CODE (t) != SSA_NAME
3710 && TREE_CODE (t) != FUNCTION_DECL
3711 && !is_gimple_val (t))
3713 error ("PHI def is not a GIMPLE value");
3714 debug_generic_stmt (phi);
3715 debug_generic_stmt (t);
3719 addr = walk_tree (&t, verify_expr, (void *) 1, NULL);
3722 debug_generic_stmt (addr);
3726 addr = walk_tree (&t, verify_node_sharing, htab, NULL);
3729 error ("Incorrect sharing of tree nodes");
3730 debug_generic_stmt (phi);
3731 debug_generic_stmt (addr);
3737 for (bsi = bsi_start (bb); !bsi_end_p (bsi); )
3739 tree stmt = bsi_stmt (bsi);
3741 err |= verify_stmt (stmt, bsi_end_p (bsi));
3742 addr = walk_tree (&stmt, verify_node_sharing, htab, NULL);
3745 error ("Incorrect sharing of tree nodes");
3746 debug_generic_stmt (stmt);
3747 debug_generic_stmt (addr);
3754 internal_error ("verify_stmts failed.");
3757 timevar_pop (TV_TREE_STMT_VERIFY);
3761 /* Verifies that the flow information is OK. */
3764 tree_verify_flow_info (void)
3768 block_stmt_iterator bsi;
3773 if (ENTRY_BLOCK_PTR->stmt_list)
3775 error ("ENTRY_BLOCK has a statement list associated with it\n");
3779 if (EXIT_BLOCK_PTR->stmt_list)
3781 error ("EXIT_BLOCK has a statement list associated with it\n");
3785 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
3786 if (e->flags & EDGE_FALLTHRU)
3788 error ("Fallthru to exit from bb %d\n", e->src->index);
3794 bool found_ctrl_stmt = false;
3798 /* Skip labels on the start of basic block. */
3799 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3801 tree prev_stmt = stmt;
3803 stmt = bsi_stmt (bsi);
3805 if (TREE_CODE (stmt) != LABEL_EXPR)
3808 if (prev_stmt && DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)))
3810 error ("Nonlocal label %s is not first "
3811 "in a sequence of labels in bb %d",
3812 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt))),
3817 if (label_to_block (LABEL_EXPR_LABEL (stmt)) != bb)
3819 error ("Label %s to block does not match in bb %d\n",
3820 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt))),
3825 if (decl_function_context (LABEL_EXPR_LABEL (stmt))
3826 != current_function_decl)
3828 error ("Label %s has incorrect context in bb %d\n",
3829 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt))),
3835 /* Verify that body of basic block BB is free of control flow. */
3836 for (; !bsi_end_p (bsi); bsi_next (&bsi))
3838 tree stmt = bsi_stmt (bsi);
3840 if (found_ctrl_stmt)
3842 error ("Control flow in the middle of basic block %d\n",
3847 if (stmt_ends_bb_p (stmt))
3848 found_ctrl_stmt = true;
3850 if (TREE_CODE (stmt) == LABEL_EXPR)
3852 error ("Label %s in the middle of basic block %d\n",
3853 IDENTIFIER_POINTER (DECL_NAME (stmt)),
3858 bsi = bsi_last (bb);
3859 if (bsi_end_p (bsi))
3862 stmt = bsi_stmt (bsi);
3864 if (is_ctrl_stmt (stmt))
3866 FOR_EACH_EDGE (e, ei, bb->succs)
3867 if (e->flags & EDGE_FALLTHRU)
3869 error ("Fallthru edge after a control statement in bb %d \n",
3875 switch (TREE_CODE (stmt))
3881 if (TREE_CODE (COND_EXPR_THEN (stmt)) != GOTO_EXPR
3882 || TREE_CODE (COND_EXPR_ELSE (stmt)) != GOTO_EXPR)
3884 error ("Structured COND_EXPR at the end of bb %d\n", bb->index);
3888 extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
3890 if (!true_edge || !false_edge
3891 || !(true_edge->flags & EDGE_TRUE_VALUE)
3892 || !(false_edge->flags & EDGE_FALSE_VALUE)
3893 || (true_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL))
3894 || (false_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL))
3895 || EDGE_COUNT (bb->succs) >= 3)
3897 error ("Wrong outgoing edge flags at end of bb %d\n",
3902 if (!has_label_p (true_edge->dest,
3903 GOTO_DESTINATION (COND_EXPR_THEN (stmt))))
3905 error ("%<then%> label does not match edge at end of bb %d\n",
3910 if (!has_label_p (false_edge->dest,
3911 GOTO_DESTINATION (COND_EXPR_ELSE (stmt))))
3913 error ("%<else%> label does not match edge at end of bb %d\n",
3921 if (simple_goto_p (stmt))
3923 error ("Explicit goto at end of bb %d\n", bb->index);
3928 /* FIXME. We should double check that the labels in the
3929 destination blocks have their address taken. */
3930 FOR_EACH_EDGE (e, ei, bb->succs)
3931 if ((e->flags & (EDGE_FALLTHRU | EDGE_TRUE_VALUE
3932 | EDGE_FALSE_VALUE))
3933 || !(e->flags & EDGE_ABNORMAL))
3935 error ("Wrong outgoing edge flags at end of bb %d\n",
3943 if (EDGE_COUNT (bb->succs) != 1
3944 || (EDGE_SUCC (bb, 0)->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL
3945 | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
3947 error ("Wrong outgoing edge flags at end of bb %d\n", bb->index);
3950 if (EDGE_SUCC (bb, 0)->dest != EXIT_BLOCK_PTR)
3952 error ("Return edge does not point to exit in bb %d\n",
3965 vec = SWITCH_LABELS (stmt);
3966 n = TREE_VEC_LENGTH (vec);
3968 /* Mark all the destination basic blocks. */
3969 for (i = 0; i < n; ++i)
3971 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
3972 basic_block label_bb = label_to_block (lab);
3974 gcc_assert (!label_bb->aux || label_bb->aux == (void *)1);
3975 label_bb->aux = (void *)1;
3978 /* Verify that the case labels are sorted. */
3979 prev = TREE_VEC_ELT (vec, 0);
3980 for (i = 1; i < n - 1; ++i)
3982 tree c = TREE_VEC_ELT (vec, i);
3985 error ("Found default case not at end of case vector");
3989 if (! tree_int_cst_lt (CASE_LOW (prev), CASE_LOW (c)))
3991 error ("Case labels not sorted:\n ");
3992 print_generic_expr (stderr, prev, 0);
3993 fprintf (stderr," is greater than ");
3994 print_generic_expr (stderr, c, 0);
3995 fprintf (stderr," but comes before it.\n");
4000 if (CASE_LOW (TREE_VEC_ELT (vec, n - 1)))
4002 error ("No default case found at end of case vector");
4006 FOR_EACH_EDGE (e, ei, bb->succs)
4010 error ("Extra outgoing edge %d->%d\n",
4011 bb->index, e->dest->index);
4014 e->dest->aux = (void *)2;
4015 if ((e->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL
4016 | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
4018 error ("Wrong outgoing edge flags at end of bb %d\n",
4024 /* Check that we have all of them. */
4025 for (i = 0; i < n; ++i)
4027 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
4028 basic_block label_bb = label_to_block (lab);
4030 if (label_bb->aux != (void *)2)
4032 error ("Missing edge %i->%i",
4033 bb->index, label_bb->index);
4038 FOR_EACH_EDGE (e, ei, bb->succs)
4039 e->dest->aux = (void *)0;
4046 if (dom_computed[CDI_DOMINATORS] >= DOM_NO_FAST_QUERY)
4047 verify_dominators (CDI_DOMINATORS);
4053 /* Updates phi nodes after creating a forwarder block joined
4054 by edge FALLTHRU. */
4057 tree_make_forwarder_block (edge fallthru)
4061 basic_block dummy, bb;
4062 tree phi, new_phi, var;
4064 dummy = fallthru->src;
4065 bb = fallthru->dest;
4067 if (EDGE_COUNT (bb->preds) == 1)
4070 /* If we redirected a branch we must create new phi nodes at the
4072 for (phi = phi_nodes (dummy); phi; phi = PHI_CHAIN (phi))
4074 var = PHI_RESULT (phi);
4075 new_phi = create_phi_node (var, bb);
4076 SSA_NAME_DEF_STMT (var) = new_phi;
4077 SET_PHI_RESULT (phi, make_ssa_name (SSA_NAME_VAR (var), phi));
4078 add_phi_arg (new_phi, PHI_RESULT (phi), fallthru);
4081 /* Ensure that the PHI node chain is in the same order. */
4082 set_phi_nodes (bb, phi_reverse (phi_nodes (bb)));
4084 /* Add the arguments we have stored on edges. */
4085 FOR_EACH_EDGE (e, ei, bb->preds)
4090 flush_pending_stmts (e);
4095 /* Return true if basic block BB does nothing except pass control
4096 flow to another block and that we can safely insert a label at
4097 the start of the successor block.
4099 As a precondition, we require that BB be not equal to
4103 tree_forwarder_block_p (basic_block bb, bool phi_wanted)
4105 block_stmt_iterator bsi;
4107 /* BB must have a single outgoing edge. */
4108 if (EDGE_COUNT (bb->succs) != 1
4109 /* If PHI_WANTED is false, BB must not have any PHI nodes.
4110 Otherwise, BB must have PHI nodes. */
4111 || (phi_nodes (bb) != NULL_TREE) != phi_wanted
4112 /* BB may not be a predecessor of EXIT_BLOCK_PTR. */
4113 || EDGE_SUCC (bb, 0)->dest == EXIT_BLOCK_PTR
4114 /* Nor should this be an infinite loop. */
4115 || EDGE_SUCC (bb, 0)->dest == bb
4116 /* BB may not have an abnormal outgoing edge. */
4117 || (EDGE_SUCC (bb, 0)->flags & EDGE_ABNORMAL))
4121 gcc_assert (bb != ENTRY_BLOCK_PTR);
4124 /* Now walk through the statements backward. We can ignore labels,
4125 anything else means this is not a forwarder block. */
4126 for (bsi = bsi_last (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4128 tree stmt = bsi_stmt (bsi);
4130 switch (TREE_CODE (stmt))
4133 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)))
4142 if (find_edge (ENTRY_BLOCK_PTR, bb))
4148 /* Protect loop latches, headers and preheaders. */
4149 if (bb->loop_father->header == bb)
4151 dest = EDGE_SUCC (bb, 0)->dest;
4153 if (dest->loop_father->header == dest)
4160 /* Return true if BB has at least one abnormal incoming edge. */
4163 has_abnormal_incoming_edge_p (basic_block bb)
4168 FOR_EACH_EDGE (e, ei, bb->preds)
4169 if (e->flags & EDGE_ABNORMAL)
4175 /* Removes forwarder block BB. Returns false if this failed. If a new
4176 forwarder block is created due to redirection of edges, it is
4177 stored to worklist. */
4180 remove_forwarder_block (basic_block bb, basic_block **worklist)
4182 edge succ = EDGE_SUCC (bb, 0), e, s;
4183 basic_block dest = succ->dest;
4187 block_stmt_iterator bsi, bsi_to;
4188 bool seen_abnormal_edge = false;
4190 /* We check for infinite loops already in tree_forwarder_block_p.
4191 However it may happen that the infinite loop is created
4192 afterwards due to removal of forwarders. */
4196 /* If the destination block consists of a nonlocal label, do not merge
4198 label = first_stmt (dest);
4200 && TREE_CODE (label) == LABEL_EXPR
4201 && DECL_NONLOCAL (LABEL_EXPR_LABEL (label)))
4204 /* If there is an abnormal edge to basic block BB, but not into
4205 dest, problems might occur during removal of the phi node at out
4206 of ssa due to overlapping live ranges of registers.
4208 If there is an abnormal edge in DEST, the problems would occur
4209 anyway since cleanup_dead_labels would then merge the labels for
4210 two different eh regions, and rest of exception handling code
4213 So if there is an abnormal edge to BB, proceed only if there is
4214 no abnormal edge to DEST and there are no phi nodes in DEST. */
4215 if (has_abnormal_incoming_edge_p (bb))
4217 seen_abnormal_edge = true;
4219 if (has_abnormal_incoming_edge_p (dest)
4220 || phi_nodes (dest) != NULL_TREE)
4224 /* If there are phi nodes in DEST, and some of the blocks that are
4225 predecessors of BB are also predecessors of DEST, check that the
4226 phi node arguments match. */
4227 if (phi_nodes (dest))
4229 FOR_EACH_EDGE (e, ei, bb->preds)
4231 s = find_edge (e->src, dest);
4235 if (!phi_alternatives_equal (dest, succ, s))
4240 /* Redirect the edges. */
4241 for (ei = ei_start (bb->preds); (e = ei_safe_edge (ei)); )
4243 if (e->flags & EDGE_ABNORMAL)
4245 /* If there is an abnormal edge, redirect it anyway, and
4246 move the labels to the new block to make it legal. */
4247 s = redirect_edge_succ_nodup (e, dest);
4250 s = redirect_edge_and_branch (e, dest);
4254 /* Create arguments for the phi nodes, since the edge was not
4256 for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi))
4257 add_phi_arg (phi, PHI_ARG_DEF (phi, succ->dest_idx), s);
4261 /* The source basic block might become a forwarder. We know
4262 that it was not a forwarder before, since it used to have
4263 at least two outgoing edges, so we may just add it to
4265 if (tree_forwarder_block_p (s->src, false))
4266 *(*worklist)++ = s->src;
4270 if (seen_abnormal_edge)
4272 /* Move the labels to the new block, so that the redirection of
4273 the abnormal edges works. */
4275 bsi_to = bsi_start (dest);
4276 for (bsi = bsi_start (bb); !bsi_end_p (bsi); )
4278 label = bsi_stmt (bsi);
4279 gcc_assert (TREE_CODE (label) == LABEL_EXPR);
4281 bsi_insert_before (&bsi_to, label, BSI_CONTINUE_LINKING);
4285 /* Update the dominators. */
4286 if (dom_info_available_p (CDI_DOMINATORS))
4288 basic_block dom, dombb, domdest;
4290 dombb = get_immediate_dominator (CDI_DOMINATORS, bb);
4291 domdest = get_immediate_dominator (CDI_DOMINATORS, dest);
4294 /* Shortcut to avoid calling (relatively expensive)
4295 nearest_common_dominator unless necessary. */
4299 dom = nearest_common_dominator (CDI_DOMINATORS, domdest, dombb);
4301 set_immediate_dominator (CDI_DOMINATORS, dest, dom);
4304 /* And kill the forwarder block. */
4305 delete_basic_block (bb);
4310 /* Removes forwarder blocks. */
4313 cleanup_forwarder_blocks (void)
4316 bool changed = false;
4317 basic_block *worklist = xmalloc (sizeof (basic_block) * n_basic_blocks);
4318 basic_block *current = worklist;
4322 if (tree_forwarder_block_p (bb, false))
4326 while (current != worklist)
4329 changed |= remove_forwarder_block (bb, ¤t);
4336 /* Merge the PHI nodes at BB into those at BB's sole successor. */
4339 remove_forwarder_block_with_phi (basic_block bb)
4341 edge succ = EDGE_SUCC (bb, 0);
4342 basic_block dest = succ->dest;
4344 basic_block dombb, domdest, dom;
4346 /* We check for infinite loops already in tree_forwarder_block_p.
4347 However it may happen that the infinite loop is created
4348 afterwards due to removal of forwarders. */
4352 /* If the destination block consists of a nonlocal label, do not
4354 label = first_stmt (dest);
4356 && TREE_CODE (label) == LABEL_EXPR
4357 && DECL_NONLOCAL (LABEL_EXPR_LABEL (label)))
4360 /* Redirect each incoming edge to BB to DEST. */
4361 while (EDGE_COUNT (bb->preds) > 0)
4363 edge e = EDGE_PRED (bb, 0), s;
4366 s = find_edge (e->src, dest);
4369 /* We already have an edge S from E->src to DEST. If S and
4370 E->dest's sole successor edge have the same PHI arguments
4371 at DEST, redirect S to DEST. */
4372 if (phi_alternatives_equal (dest, s, succ))
4374 e = redirect_edge_and_branch (e, dest);
4375 PENDING_STMT (e) = NULL_TREE;
4379 /* PHI arguments are different. Create a forwarder block by
4380 splitting E so that we can merge PHI arguments on E to
4382 e = EDGE_SUCC (split_edge (e), 0);
4385 s = redirect_edge_and_branch (e, dest);
4387 /* redirect_edge_and_branch must not create a new edge. */
4388 gcc_assert (s == e);
4390 /* Add to the PHI nodes at DEST each PHI argument removed at the
4391 destination of E. */
4392 for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi))
4394 tree def = PHI_ARG_DEF (phi, succ->dest_idx);
4396 if (TREE_CODE (def) == SSA_NAME)
4400 /* If DEF is one of the results of PHI nodes removed during
4401 redirection, replace it with the PHI argument that used
4403 for (var = PENDING_STMT (e); var; var = TREE_CHAIN (var))
4405 tree old_arg = TREE_PURPOSE (var);
4406 tree new_arg = TREE_VALUE (var);
4416 add_phi_arg (phi, def, s);
4419 PENDING_STMT (e) = NULL;
4422 /* Update the dominators. */
4423 dombb = get_immediate_dominator (CDI_DOMINATORS, bb);
4424 domdest = get_immediate_dominator (CDI_DOMINATORS, dest);
4427 /* Shortcut to avoid calling (relatively expensive)
4428 nearest_common_dominator unless necessary. */
4432 dom = nearest_common_dominator (CDI_DOMINATORS, domdest, dombb);
4434 set_immediate_dominator (CDI_DOMINATORS, dest, dom);
4436 /* Remove BB since all of BB's incoming edges have been redirected
4438 delete_basic_block (bb);
4441 /* This pass merges PHI nodes if one feeds into another. For example,
4442 suppose we have the following:
4449 # tem_6 = PHI <tem_17(8), tem_23(7)>;
4452 # tem_3 = PHI <tem_6(9), tem_2(5)>;
4455 Then we merge the first PHI node into the second one like so:
4457 goto <bb 9> (<L10>);
4462 # tem_3 = PHI <tem_23(7), tem_2(5), tem_17(8)>;
4467 merge_phi_nodes (void)
4469 basic_block *worklist = xmalloc (sizeof (basic_block) * n_basic_blocks);
4470 basic_block *current = worklist;
4473 calculate_dominance_info (CDI_DOMINATORS);
4475 /* Find all PHI nodes that we may be able to merge. */
4480 /* Look for a forwarder block with PHI nodes. */
4481 if (!tree_forwarder_block_p (bb, true))
4484 dest = EDGE_SUCC (bb, 0)->dest;
4486 /* We have to feed into another basic block with PHI
4488 if (!phi_nodes (dest)
4489 /* We don't want to deal with a basic block with
4491 || has_abnormal_incoming_edge_p (bb))
4494 if (!dominated_by_p (CDI_DOMINATORS, dest, bb))
4496 /* If BB does not dominate DEST, then the PHI nodes at
4497 DEST must be the only users of the results of the PHI
4503 /* Now let's drain WORKLIST. */
4504 while (current != worklist)
4507 remove_forwarder_block_with_phi (bb);
4514 gate_merge_phi (void)
4519 struct tree_opt_pass pass_merge_phi = {
4520 "mergephi", /* name */
4521 gate_merge_phi, /* gate */
4522 merge_phi_nodes, /* execute */
4525 0, /* static_pass_number */
4526 TV_TREE_MERGE_PHI, /* tv_id */
4527 PROP_cfg | PROP_ssa, /* properties_required */
4528 0, /* properties_provided */
4529 0, /* properties_destroyed */
4530 0, /* todo_flags_start */
4531 TODO_dump_func | TODO_ggc_collect /* todo_flags_finish */
4536 /* Return a non-special label in the head of basic block BLOCK.
4537 Create one if it doesn't exist. */
4540 tree_block_label (basic_block bb)
4542 block_stmt_iterator i, s = bsi_start (bb);
4546 for (i = s; !bsi_end_p (i); first = false, bsi_next (&i))
4548 stmt = bsi_stmt (i);
4549 if (TREE_CODE (stmt) != LABEL_EXPR)
4551 label = LABEL_EXPR_LABEL (stmt);
4552 if (!DECL_NONLOCAL (label))
4555 bsi_move_before (&i, &s);
4560 label = create_artificial_label ();
4561 stmt = build1 (LABEL_EXPR, void_type_node, label);
4562 bsi_insert_before (&s, stmt, BSI_NEW_STMT);
4567 /* Attempt to perform edge redirection by replacing a possibly complex
4568 jump instruction by a goto or by removing the jump completely.
4569 This can apply only if all edges now point to the same block. The
4570 parameters and return values are equivalent to
4571 redirect_edge_and_branch. */
4574 tree_try_redirect_by_replacing_jump (edge e, basic_block target)
4576 basic_block src = e->src;
4577 block_stmt_iterator b;
4580 /* We can replace or remove a complex jump only when we have exactly
4582 if (EDGE_COUNT (src->succs) != 2
4583 /* Verify that all targets will be TARGET. Specifically, the
4584 edge that is not E must also go to TARGET. */
4585 || EDGE_SUCC (src, EDGE_SUCC (src, 0) == e)->dest != target)
4591 stmt = bsi_stmt (b);
4593 if (TREE_CODE (stmt) == COND_EXPR
4594 || TREE_CODE (stmt) == SWITCH_EXPR)
4597 e = ssa_redirect_edge (e, target);
4598 e->flags = EDGE_FALLTHRU;
4606 /* Redirect E to DEST. Return NULL on failure. Otherwise, return the
4607 edge representing the redirected branch. */
4610 tree_redirect_edge_and_branch (edge e, basic_block dest)
4612 basic_block bb = e->src;
4613 block_stmt_iterator bsi;
4617 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
4620 if (e->src != ENTRY_BLOCK_PTR
4621 && (ret = tree_try_redirect_by_replacing_jump (e, dest)))
4624 if (e->dest == dest)
4627 label = tree_block_label (dest);
4629 bsi = bsi_last (bb);
4630 stmt = bsi_end_p (bsi) ? NULL : bsi_stmt (bsi);
4632 switch (stmt ? TREE_CODE (stmt) : ERROR_MARK)
4635 stmt = (e->flags & EDGE_TRUE_VALUE
4636 ? COND_EXPR_THEN (stmt)
4637 : COND_EXPR_ELSE (stmt));
4638 GOTO_DESTINATION (stmt) = label;
4642 /* No non-abnormal edges should lead from a non-simple goto, and
4643 simple ones should be represented implicitly. */
4648 tree cases = get_cases_for_edge (e, stmt);
4650 /* If we have a list of cases associated with E, then use it
4651 as it's a lot faster than walking the entire case vector. */
4654 edge e2 = find_edge (e->src, dest);
4661 CASE_LABEL (cases) = label;
4662 cases = TREE_CHAIN (cases);
4665 /* If there was already an edge in the CFG, then we need
4666 to move all the cases associated with E to E2. */
4669 tree cases2 = get_cases_for_edge (e2, stmt);
4671 TREE_CHAIN (last) = TREE_CHAIN (cases2);
4672 TREE_CHAIN (cases2) = first;
4677 tree vec = SWITCH_LABELS (stmt);
4678 size_t i, n = TREE_VEC_LENGTH (vec);
4680 for (i = 0; i < n; i++)
4682 tree elt = TREE_VEC_ELT (vec, i);
4684 if (label_to_block (CASE_LABEL (elt)) == e->dest)
4685 CASE_LABEL (elt) = label;
4694 e->flags |= EDGE_FALLTHRU;
4698 /* Otherwise it must be a fallthru edge, and we don't need to
4699 do anything besides redirecting it. */
4700 gcc_assert (e->flags & EDGE_FALLTHRU);
4704 /* Update/insert PHI nodes as necessary. */
4706 /* Now update the edges in the CFG. */
4707 e = ssa_redirect_edge (e, dest);
4713 /* Simple wrapper, as we can always redirect fallthru edges. */
4716 tree_redirect_edge_and_branch_force (edge e, basic_block dest)
4718 e = tree_redirect_edge_and_branch (e, dest);
4725 /* Splits basic block BB after statement STMT (but at least after the
4726 labels). If STMT is NULL, BB is split just after the labels. */
4729 tree_split_block (basic_block bb, void *stmt)
4731 block_stmt_iterator bsi, bsi_tgt;
4737 new_bb = create_empty_bb (bb);
4739 /* Redirect the outgoing edges. */
4740 new_bb->succs = bb->succs;
4742 FOR_EACH_EDGE (e, ei, new_bb->succs)
4745 if (stmt && TREE_CODE ((tree) stmt) == LABEL_EXPR)
4748 /* Move everything from BSI to the new basic block. */
4749 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4751 act = bsi_stmt (bsi);
4752 if (TREE_CODE (act) == LABEL_EXPR)
4765 bsi_tgt = bsi_start (new_bb);
4766 while (!bsi_end_p (bsi))
4768 act = bsi_stmt (bsi);
4770 bsi_insert_after (&bsi_tgt, act, BSI_NEW_STMT);
4777 /* Moves basic block BB after block AFTER. */
4780 tree_move_block_after (basic_block bb, basic_block after)
4782 if (bb->prev_bb == after)
4786 link_block (bb, after);
4792 /* Return true if basic_block can be duplicated. */
4795 tree_can_duplicate_bb_p (basic_block bb ATTRIBUTE_UNUSED)
4800 /* Create a duplicate of the basic block BB. NOTE: This does not
4801 preserve SSA form. */
4804 tree_duplicate_bb (basic_block bb)
4807 block_stmt_iterator bsi, bsi_tgt;
4809 ssa_op_iter op_iter;
4811 new_bb = create_empty_bb (EXIT_BLOCK_PTR->prev_bb);
4813 /* First copy the phi nodes. We do not copy phi node arguments here,
4814 since the edges are not ready yet. Keep the chain of phi nodes in
4815 the same order, so that we can add them later. */
4816 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
4818 mark_for_rewrite (PHI_RESULT (phi));
4819 create_phi_node (PHI_RESULT (phi), new_bb);
4821 set_phi_nodes (new_bb, phi_reverse (phi_nodes (new_bb)));
4823 bsi_tgt = bsi_start (new_bb);
4824 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4826 tree stmt = bsi_stmt (bsi);
4829 if (TREE_CODE (stmt) == LABEL_EXPR)
4832 /* Record the definitions. */
4833 get_stmt_operands (stmt);
4835 FOR_EACH_SSA_TREE_OPERAND (val, stmt, op_iter, SSA_OP_ALL_DEFS)
4836 mark_for_rewrite (val);
4838 copy = unshare_expr (stmt);
4840 /* Copy also the virtual operands. */
4841 get_stmt_ann (copy);
4842 copy_virtual_operands (copy, stmt);
4844 bsi_insert_after (&bsi_tgt, copy, BSI_NEW_STMT);
4850 /* Basic block BB_COPY was created by code duplication. Add phi node
4851 arguments for edges going out of BB_COPY. The blocks that were
4852 duplicated have rbi->duplicated set to one. */
4855 add_phi_args_after_copy_bb (basic_block bb_copy)
4857 basic_block bb, dest;
4860 tree phi, phi_copy, phi_next, def;
4862 bb = bb_copy->rbi->original;
4864 FOR_EACH_EDGE (e_copy, ei, bb_copy->succs)
4866 if (!phi_nodes (e_copy->dest))
4869 if (e_copy->dest->rbi->duplicated)
4870 dest = e_copy->dest->rbi->original;
4872 dest = e_copy->dest;
4874 e = find_edge (bb, dest);
4877 /* During loop unrolling the target of the latch edge is copied.
4878 In this case we are not looking for edge to dest, but to
4879 duplicated block whose original was dest. */
4880 FOR_EACH_EDGE (e, ei, bb->succs)
4881 if (e->dest->rbi->duplicated
4882 && e->dest->rbi->original == dest)
4885 gcc_assert (e != NULL);
4888 for (phi = phi_nodes (e->dest), phi_copy = phi_nodes (e_copy->dest);
4890 phi = phi_next, phi_copy = PHI_CHAIN (phi_copy))
4892 phi_next = PHI_CHAIN (phi);
4894 gcc_assert (PHI_RESULT (phi) == PHI_RESULT (phi_copy));
4895 def = PHI_ARG_DEF_FROM_EDGE (phi, e);
4896 add_phi_arg (phi_copy, def, e_copy);
4901 /* Blocks in REGION_COPY array of length N_REGION were created by
4902 duplication of basic blocks. Add phi node arguments for edges
4903 going from these blocks. */
4906 add_phi_args_after_copy (basic_block *region_copy, unsigned n_region)
4910 for (i = 0; i < n_region; i++)
4911 region_copy[i]->rbi->duplicated = 1;
4913 for (i = 0; i < n_region; i++)
4914 add_phi_args_after_copy_bb (region_copy[i]);
4916 for (i = 0; i < n_region; i++)
4917 region_copy[i]->rbi->duplicated = 0;
4920 /* Maps the old ssa name FROM_NAME to TO_NAME. */
4922 struct ssa_name_map_entry
4928 /* Hash function for ssa_name_map_entry. */
4931 ssa_name_map_entry_hash (const void *entry)
4933 const struct ssa_name_map_entry *en = entry;
4934 return SSA_NAME_VERSION (en->from_name);
4937 /* Equality function for ssa_name_map_entry. */
4940 ssa_name_map_entry_eq (const void *in_table, const void *ssa_name)
4942 const struct ssa_name_map_entry *en = in_table;
4944 return en->from_name == ssa_name;
4947 /* Allocate duplicates of ssa names in list DEFINITIONS and store the mapping
4951 allocate_ssa_names (bitmap definitions, htab_t *map)
4954 struct ssa_name_map_entry *entry;
4960 *map = htab_create (10, ssa_name_map_entry_hash,
4961 ssa_name_map_entry_eq, free);
4962 EXECUTE_IF_SET_IN_BITMAP (definitions, 0, ver, bi)
4964 name = ssa_name (ver);
4965 slot = htab_find_slot_with_hash (*map, name, SSA_NAME_VERSION (name),
4971 entry = xmalloc (sizeof (struct ssa_name_map_entry));
4972 entry->from_name = name;
4975 entry->to_name = duplicate_ssa_name (name, SSA_NAME_DEF_STMT (name));
4979 /* Rewrite the definition DEF in statement STMT to new ssa name as specified
4980 by the mapping MAP. */
4983 rewrite_to_new_ssa_names_def (def_operand_p def, tree stmt, htab_t map)
4985 tree name = DEF_FROM_PTR (def);
4986 struct ssa_name_map_entry *entry;
4988 gcc_assert (TREE_CODE (name) == SSA_NAME);
4990 entry = htab_find_with_hash (map, name, SSA_NAME_VERSION (name));
4994 SET_DEF (def, entry->to_name);
4995 SSA_NAME_DEF_STMT (entry->to_name) = stmt;
4998 /* Rewrite the USE to new ssa name as specified by the mapping MAP. */
5001 rewrite_to_new_ssa_names_use (use_operand_p use, htab_t map)
5003 tree name = USE_FROM_PTR (use);
5004 struct ssa_name_map_entry *entry;
5006 if (TREE_CODE (name) != SSA_NAME)
5009 entry = htab_find_with_hash (map, name, SSA_NAME_VERSION (name));
5013 SET_USE (use, entry->to_name);
5016 /* Rewrite the ssa names in basic block BB to new ones as specified by the
5020 rewrite_to_new_ssa_names_bb (basic_block bb, htab_t map)
5026 block_stmt_iterator bsi;
5030 v_may_def_optype v_may_defs;
5031 v_must_def_optype v_must_defs;
5034 FOR_EACH_EDGE (e, ei, bb->preds)
5035 if (e->flags & EDGE_ABNORMAL)
5038 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
5040 rewrite_to_new_ssa_names_def (PHI_RESULT_PTR (phi), phi, map);
5042 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (PHI_RESULT (phi)) = 1;
5045 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
5047 stmt = bsi_stmt (bsi);
5048 get_stmt_operands (stmt);
5049 ann = stmt_ann (stmt);
5051 uses = USE_OPS (ann);
5052 for (i = 0; i < NUM_USES (uses); i++)
5053 rewrite_to_new_ssa_names_use (USE_OP_PTR (uses, i), map);
5055 defs = DEF_OPS (ann);
5056 for (i = 0; i < NUM_DEFS (defs); i++)
5057 rewrite_to_new_ssa_names_def (DEF_OP_PTR (defs, i), stmt, map);
5059 vuses = VUSE_OPS (ann);
5060 for (i = 0; i < NUM_VUSES (vuses); i++)
5061 rewrite_to_new_ssa_names_use (VUSE_OP_PTR (vuses, i), map);
5063 v_may_defs = V_MAY_DEF_OPS (ann);
5064 for (i = 0; i < NUM_V_MAY_DEFS (v_may_defs); i++)
5066 rewrite_to_new_ssa_names_use
5067 (V_MAY_DEF_OP_PTR (v_may_defs, i), map);
5068 rewrite_to_new_ssa_names_def
5069 (V_MAY_DEF_RESULT_PTR (v_may_defs, i), stmt, map);
5072 v_must_defs = V_MUST_DEF_OPS (ann);
5073 for (i = 0; i < NUM_V_MUST_DEFS (v_must_defs); i++)
5075 rewrite_to_new_ssa_names_def
5076 (V_MUST_DEF_RESULT_PTR (v_must_defs, i), stmt, map);
5077 rewrite_to_new_ssa_names_use
5078 (V_MUST_DEF_KILL_PTR (v_must_defs, i), map);
5082 FOR_EACH_EDGE (e, ei, bb->succs)
5083 for (phi = phi_nodes (e->dest); phi; phi = PHI_CHAIN (phi))
5085 rewrite_to_new_ssa_names_use
5086 (PHI_ARG_DEF_PTR_FROM_EDGE (phi, e), map);
5088 if (e->flags & EDGE_ABNORMAL)
5090 tree op = PHI_ARG_DEF_FROM_EDGE (phi, e);
5091 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op) = 1;
5096 /* Rewrite the ssa names in N_REGION blocks REGION to the new ones as specified
5097 by the mapping MAP. */
5100 rewrite_to_new_ssa_names (basic_block *region, unsigned n_region, htab_t map)
5104 for (r = 0; r < n_region; r++)
5105 rewrite_to_new_ssa_names_bb (region[r], map);
5108 /* Duplicates a REGION (set of N_REGION basic blocks) with just a single
5109 important exit edge EXIT. By important we mean that no SSA name defined
5110 inside region is live over the other exit edges of the region. All entry
5111 edges to the region must go to ENTRY->dest. The edge ENTRY is redirected
5112 to the duplicate of the region. SSA form, dominance and loop information
5113 is updated. The new basic blocks are stored to REGION_COPY in the same
5114 order as they had in REGION, provided that REGION_COPY is not NULL.
5115 The function returns false if it is unable to copy the region,
5119 tree_duplicate_sese_region (edge entry, edge exit,
5120 basic_block *region, unsigned n_region,
5121 basic_block *region_copy)
5123 unsigned i, n_doms, ver;
5124 bool free_region_copy = false, copying_header = false;
5125 struct loop *loop = entry->dest->loop_father;
5130 htab_t ssa_name_map = NULL;
5134 if (!can_copy_bbs_p (region, n_region))
5137 /* Some sanity checking. Note that we do not check for all possible
5138 missuses of the functions. I.e. if you ask to copy something weird,
5139 it will work, but the state of structures probably will not be
5142 for (i = 0; i < n_region; i++)
5144 /* We do not handle subloops, i.e. all the blocks must belong to the
5146 if (region[i]->loop_father != loop)
5149 if (region[i] != entry->dest
5150 && region[i] == loop->header)
5156 /* In case the function is used for loop header copying (which is the primary
5157 use), ensure that EXIT and its copy will be new latch and entry edges. */
5158 if (loop->header == entry->dest)
5160 copying_header = true;
5161 loop->copy = loop->outer;
5163 if (!dominated_by_p (CDI_DOMINATORS, loop->latch, exit->src))
5166 for (i = 0; i < n_region; i++)
5167 if (region[i] != exit->src
5168 && dominated_by_p (CDI_DOMINATORS, region[i], exit->src))
5174 region_copy = xmalloc (sizeof (basic_block) * n_region);
5175 free_region_copy = true;
5178 gcc_assert (!any_marked_for_rewrite_p ());
5180 /* Record blocks outside the region that are duplicated by something
5182 doms = xmalloc (sizeof (basic_block) * n_basic_blocks);
5183 n_doms = get_dominated_by_region (CDI_DOMINATORS, region, n_region, doms);
5185 copy_bbs (region, n_region, region_copy, &exit, 1, &exit_copy, loop);
5186 definitions = marked_ssa_names ();
5190 loop->header = exit->dest;
5191 loop->latch = exit->src;
5194 /* Redirect the entry and add the phi node arguments. */
5195 redirected = redirect_edge_and_branch (entry, entry->dest->rbi->copy);
5196 gcc_assert (redirected != NULL);
5197 flush_pending_stmts (entry);
5199 /* Concerning updating of dominators: We must recount dominators
5200 for entry block and its copy. Anything that is outside of the region, but
5201 was dominated by something inside needs recounting as well. */
5202 set_immediate_dominator (CDI_DOMINATORS, entry->dest, entry->src);
5203 doms[n_doms++] = entry->dest->rbi->original;
5204 iterate_fix_dominators (CDI_DOMINATORS, doms, n_doms);
5207 /* Add the other phi node arguments. */
5208 add_phi_args_after_copy (region_copy, n_region);
5210 /* Add phi nodes for definitions at exit. TODO -- once we have immediate
5211 uses, it should be possible to emit phi nodes just for definitions that
5212 are used outside region. */
5213 EXECUTE_IF_SET_IN_BITMAP (definitions, 0, ver, bi)
5215 tree name = ssa_name (ver);
5217 phi = create_phi_node (name, exit->dest);
5218 add_phi_arg (phi, name, exit);
5219 add_phi_arg (phi, name, exit_copy);
5221 SSA_NAME_DEF_STMT (name) = phi;
5224 /* And create new definitions inside region and its copy. TODO -- once we
5225 have immediate uses, it might be better to leave definitions in region
5226 unchanged, create new ssa names for phi nodes on exit, and rewrite
5227 the uses, to avoid changing the copied region. */
5228 allocate_ssa_names (definitions, &ssa_name_map);
5229 rewrite_to_new_ssa_names (region, n_region, ssa_name_map);
5230 allocate_ssa_names (definitions, &ssa_name_map);
5231 rewrite_to_new_ssa_names (region_copy, n_region, ssa_name_map);
5232 htab_delete (ssa_name_map);
5234 if (free_region_copy)
5237 unmark_all_for_rewrite ();
5238 BITMAP_FREE (definitions);
5243 /* Dump FUNCTION_DECL FN to file FILE using FLAGS (see TDF_* in tree.h) */
5246 dump_function_to_file (tree fn, FILE *file, int flags)
5248 tree arg, vars, var;
5249 bool ignore_topmost_bind = false, any_var = false;
5253 fprintf (file, "%s (", lang_hooks.decl_printable_name (fn, 2));
5255 arg = DECL_ARGUMENTS (fn);
5258 print_generic_expr (file, arg, dump_flags);
5259 if (TREE_CHAIN (arg))
5260 fprintf (file, ", ");
5261 arg = TREE_CHAIN (arg);
5263 fprintf (file, ")\n");
5265 if (flags & TDF_RAW)
5267 dump_node (fn, TDF_SLIM | flags, file);
5271 /* When GIMPLE is lowered, the variables are no longer available in
5272 BIND_EXPRs, so display them separately. */
5273 if (cfun && cfun->unexpanded_var_list)
5275 ignore_topmost_bind = true;
5277 fprintf (file, "{\n");
5278 for (vars = cfun->unexpanded_var_list; vars; vars = TREE_CHAIN (vars))
5280 var = TREE_VALUE (vars);
5282 print_generic_decl (file, var, flags);
5283 fprintf (file, "\n");
5289 if (basic_block_info)
5291 /* Make a CFG based dump. */
5292 check_bb_profile (ENTRY_BLOCK_PTR, file);
5293 if (!ignore_topmost_bind)
5294 fprintf (file, "{\n");
5296 if (any_var && n_basic_blocks)
5297 fprintf (file, "\n");
5300 dump_generic_bb (file, bb, 2, flags);
5302 fprintf (file, "}\n");
5303 check_bb_profile (EXIT_BLOCK_PTR, file);
5309 /* Make a tree based dump. */
5310 chain = DECL_SAVED_TREE (fn);
5312 if (TREE_CODE (chain) == BIND_EXPR)
5314 if (ignore_topmost_bind)
5316 chain = BIND_EXPR_BODY (chain);
5324 if (!ignore_topmost_bind)
5325 fprintf (file, "{\n");
5330 fprintf (file, "\n");
5332 print_generic_stmt_indented (file, chain, flags, indent);
5333 if (ignore_topmost_bind)
5334 fprintf (file, "}\n");
5337 fprintf (file, "\n\n");
5341 /* Pretty print of the loops intermediate representation. */
5342 static void print_loop (FILE *, struct loop *, int);
5343 static void print_pred_bbs (FILE *, basic_block bb);
5344 static void print_succ_bbs (FILE *, basic_block bb);
5347 /* Print the predecessors indexes of edge E on FILE. */
5350 print_pred_bbs (FILE *file, basic_block bb)
5355 FOR_EACH_EDGE (e, ei, bb->preds)
5356 fprintf (file, "bb_%d", e->src->index);
5360 /* Print the successors indexes of edge E on FILE. */
5363 print_succ_bbs (FILE *file, basic_block bb)
5368 FOR_EACH_EDGE (e, ei, bb->succs)
5369 fprintf (file, "bb_%d", e->src->index);
5373 /* Pretty print LOOP on FILE, indented INDENT spaces. */
5376 print_loop (FILE *file, struct loop *loop, int indent)
5384 s_indent = (char *) alloca ((size_t) indent + 1);
5385 memset ((void *) s_indent, ' ', (size_t) indent);
5386 s_indent[indent] = '\0';
5388 /* Print the loop's header. */
5389 fprintf (file, "%sloop_%d\n", s_indent, loop->num);
5391 /* Print the loop's body. */
5392 fprintf (file, "%s{\n", s_indent);
5394 if (bb->loop_father == loop)
5396 /* Print the basic_block's header. */
5397 fprintf (file, "%s bb_%d (preds = {", s_indent, bb->index);
5398 print_pred_bbs (file, bb);
5399 fprintf (file, "}, succs = {");
5400 print_succ_bbs (file, bb);
5401 fprintf (file, "})\n");
5403 /* Print the basic_block's body. */
5404 fprintf (file, "%s {\n", s_indent);
5405 tree_dump_bb (bb, file, indent + 4);
5406 fprintf (file, "%s }\n", s_indent);
5409 print_loop (file, loop->inner, indent + 2);
5410 fprintf (file, "%s}\n", s_indent);
5411 print_loop (file, loop->next, indent);
5415 /* Follow a CFG edge from the entry point of the program, and on entry
5416 of a loop, pretty print the loop structure on FILE. */
5419 print_loop_ir (FILE *file)
5423 bb = BASIC_BLOCK (0);
5424 if (bb && bb->loop_father)
5425 print_loop (file, bb->loop_father, 0);
5429 /* Debugging loops structure at tree level. */
5432 debug_loop_ir (void)
5434 print_loop_ir (stderr);
5438 /* Return true if BB ends with a call, possibly followed by some
5439 instructions that must stay with the call. Return false,
5443 tree_block_ends_with_call_p (basic_block bb)
5445 block_stmt_iterator bsi = bsi_last (bb);
5446 return get_call_expr_in (bsi_stmt (bsi)) != NULL;
5450 /* Return true if BB ends with a conditional branch. Return false,
5454 tree_block_ends_with_condjump_p (basic_block bb)
5456 tree stmt = tsi_stmt (bsi_last (bb).tsi);
5457 return (TREE_CODE (stmt) == COND_EXPR);
5461 /* Return true if we need to add fake edge to exit at statement T.
5462 Helper function for tree_flow_call_edges_add. */
5465 need_fake_edge_p (tree t)
5469 /* NORETURN and LONGJMP calls already have an edge to exit.
5470 CONST and PURE calls do not need one.
5471 We don't currently check for CONST and PURE here, although
5472 it would be a good idea, because those attributes are
5473 figured out from the RTL in mark_constant_function, and
5474 the counter incrementation code from -fprofile-arcs
5475 leads to different results from -fbranch-probabilities. */
5476 call = get_call_expr_in (t);
5478 && !(call_expr_flags (call) & ECF_NORETURN))
5481 if (TREE_CODE (t) == ASM_EXPR
5482 && (ASM_VOLATILE_P (t) || ASM_INPUT_P (t)))
5489 /* Add fake edges to the function exit for any non constant and non
5490 noreturn calls, volatile inline assembly in the bitmap of blocks
5491 specified by BLOCKS or to the whole CFG if BLOCKS is zero. Return
5492 the number of blocks that were split.
5494 The goal is to expose cases in which entering a basic block does
5495 not imply that all subsequent instructions must be executed. */
5498 tree_flow_call_edges_add (sbitmap blocks)
5501 int blocks_split = 0;
5502 int last_bb = last_basic_block;
5503 bool check_last_block = false;
5505 if (n_basic_blocks == 0)
5509 check_last_block = true;
5511 check_last_block = TEST_BIT (blocks, EXIT_BLOCK_PTR->prev_bb->index);
5513 /* In the last basic block, before epilogue generation, there will be
5514 a fallthru edge to EXIT. Special care is required if the last insn
5515 of the last basic block is a call because make_edge folds duplicate
5516 edges, which would result in the fallthru edge also being marked
5517 fake, which would result in the fallthru edge being removed by
5518 remove_fake_edges, which would result in an invalid CFG.
5520 Moreover, we can't elide the outgoing fake edge, since the block
5521 profiler needs to take this into account in order to solve the minimal
5522 spanning tree in the case that the call doesn't return.
5524 Handle this by adding a dummy instruction in a new last basic block. */
5525 if (check_last_block)
5527 basic_block bb = EXIT_BLOCK_PTR->prev_bb;
5528 block_stmt_iterator bsi = bsi_last (bb);
5530 if (!bsi_end_p (bsi))
5533 if (need_fake_edge_p (t))
5537 e = find_edge (bb, EXIT_BLOCK_PTR);
5540 bsi_insert_on_edge (e, build_empty_stmt ());
5541 bsi_commit_edge_inserts ();
5546 /* Now add fake edges to the function exit for any non constant
5547 calls since there is no way that we can determine if they will
5549 for (i = 0; i < last_bb; i++)
5551 basic_block bb = BASIC_BLOCK (i);
5552 block_stmt_iterator bsi;
5553 tree stmt, last_stmt;
5558 if (blocks && !TEST_BIT (blocks, i))
5561 bsi = bsi_last (bb);
5562 if (!bsi_end_p (bsi))
5564 last_stmt = bsi_stmt (bsi);
5567 stmt = bsi_stmt (bsi);
5568 if (need_fake_edge_p (stmt))
5571 /* The handling above of the final block before the
5572 epilogue should be enough to verify that there is
5573 no edge to the exit block in CFG already.
5574 Calling make_edge in such case would cause us to
5575 mark that edge as fake and remove it later. */
5576 #ifdef ENABLE_CHECKING
5577 if (stmt == last_stmt)
5579 e = find_edge (bb, EXIT_BLOCK_PTR);
5580 gcc_assert (e == NULL);
5584 /* Note that the following may create a new basic block
5585 and renumber the existing basic blocks. */
5586 if (stmt != last_stmt)
5588 e = split_block (bb, stmt);
5592 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
5596 while (!bsi_end_p (bsi));
5601 verify_flow_info ();
5603 return blocks_split;
5607 tree_purge_dead_eh_edges (basic_block bb)
5609 bool changed = false;
5612 tree stmt = last_stmt (bb);
5614 if (stmt && tree_can_throw_internal (stmt))
5617 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
5619 if (e->flags & EDGE_EH)
5628 /* Removal of dead EH edges might change dominators of not
5629 just immediate successors. E.g. when bb1 is changed so that
5630 it no longer can throw and bb1->bb3 and bb1->bb4 are dead
5631 eh edges purged by this function in:
5643 idom(bb5) must be recomputed. For now just free the dominance
5646 free_dominance_info (CDI_DOMINATORS);
5652 tree_purge_all_dead_eh_edges (bitmap blocks)
5654 bool changed = false;
5658 EXECUTE_IF_SET_IN_BITMAP (blocks, 0, i, bi)
5660 changed |= tree_purge_dead_eh_edges (BASIC_BLOCK (i));
5666 /* This function is called whenever a new edge is created or
5670 tree_execute_on_growing_pred (edge e)
5672 basic_block bb = e->dest;
5675 reserve_phi_args_for_new_edge (bb);
5678 /* This function is called immediately before edge E is removed from
5679 the edge vector E->dest->preds. */
5682 tree_execute_on_shrinking_pred (edge e)
5684 if (phi_nodes (e->dest))
5685 remove_phi_args (e);
5688 struct cfg_hooks tree_cfg_hooks = {
5690 tree_verify_flow_info,
5691 tree_dump_bb, /* dump_bb */
5692 create_bb, /* create_basic_block */
5693 tree_redirect_edge_and_branch,/* redirect_edge_and_branch */
5694 tree_redirect_edge_and_branch_force,/* redirect_edge_and_branch_force */
5695 remove_bb, /* delete_basic_block */
5696 tree_split_block, /* split_block */
5697 tree_move_block_after, /* move_block_after */
5698 tree_can_merge_blocks_p, /* can_merge_blocks_p */
5699 tree_merge_blocks, /* merge_blocks */
5700 tree_predict_edge, /* predict_edge */
5701 tree_predicted_by_p, /* predicted_by_p */
5702 tree_can_duplicate_bb_p, /* can_duplicate_block_p */
5703 tree_duplicate_bb, /* duplicate_block */
5704 tree_split_edge, /* split_edge */
5705 tree_make_forwarder_block, /* make_forward_block */
5706 NULL, /* tidy_fallthru_edge */
5707 tree_block_ends_with_call_p, /* block_ends_with_call_p */
5708 tree_block_ends_with_condjump_p, /* block_ends_with_condjump_p */
5709 tree_flow_call_edges_add, /* flow_call_edges_add */
5710 tree_execute_on_growing_pred, /* execute_on_growing_pred */
5711 tree_execute_on_shrinking_pred, /* execute_on_shrinking_pred */
5715 /* Split all critical edges. */
5718 split_critical_edges (void)
5724 /* split_edge can redirect edges out of SWITCH_EXPRs, which can get
5725 expensive. So we want to enable recording of edge to CASE_LABEL_EXPR
5726 mappings around the calls to split_edge. */
5727 start_recording_case_labels ();
5730 FOR_EACH_EDGE (e, ei, bb->succs)
5731 if (EDGE_CRITICAL_P (e) && !(e->flags & EDGE_ABNORMAL))
5736 end_recording_case_labels ();
5739 struct tree_opt_pass pass_split_crit_edges =
5741 "crited", /* name */
5743 split_critical_edges, /* execute */
5746 0, /* static_pass_number */
5747 TV_TREE_SPLIT_EDGES, /* tv_id */
5748 PROP_cfg, /* properties required */
5749 PROP_no_crit_edges, /* properties_provided */
5750 0, /* properties_destroyed */
5751 0, /* todo_flags_start */
5752 TODO_dump_func, /* todo_flags_finish */
5757 /* Return EXP if it is a valid GIMPLE rvalue, else gimplify it into
5758 a temporary, make sure and register it to be renamed if necessary,
5759 and finally return the temporary. Put the statements to compute
5760 EXP before the current statement in BSI. */
5763 gimplify_val (block_stmt_iterator *bsi, tree type, tree exp)
5765 tree t, new_stmt, orig_stmt;
5767 if (is_gimple_val (exp))
5770 t = make_rename_temp (type, NULL);
5771 new_stmt = build (MODIFY_EXPR, type, t, exp);
5773 orig_stmt = bsi_stmt (*bsi);
5774 SET_EXPR_LOCUS (new_stmt, EXPR_LOCUS (orig_stmt));
5775 TREE_BLOCK (new_stmt) = TREE_BLOCK (orig_stmt);
5777 bsi_insert_before (bsi, new_stmt, BSI_SAME_STMT);
5782 /* Build a ternary operation and gimplify it. Emit code before BSI.
5783 Return the gimple_val holding the result. */
5786 gimplify_build3 (block_stmt_iterator *bsi, enum tree_code code,
5787 tree type, tree a, tree b, tree c)
5791 ret = fold (build3 (code, type, a, b, c));
5794 return gimplify_val (bsi, type, ret);
5797 /* Build a binary operation and gimplify it. Emit code before BSI.
5798 Return the gimple_val holding the result. */
5801 gimplify_build2 (block_stmt_iterator *bsi, enum tree_code code,
5802 tree type, tree a, tree b)
5806 ret = fold (build2 (code, type, a, b));
5809 return gimplify_val (bsi, type, ret);
5812 /* Build a unary operation and gimplify it. Emit code before BSI.
5813 Return the gimple_val holding the result. */
5816 gimplify_build1 (block_stmt_iterator *bsi, enum tree_code code, tree type,
5821 ret = fold (build1 (code, type, a));
5824 return gimplify_val (bsi, type, ret);
5829 /* Emit return warnings. */
5832 execute_warn_function_return (void)
5834 #ifdef USE_MAPPED_LOCATION
5835 source_location location;
5843 if (warn_missing_noreturn
5844 && !TREE_THIS_VOLATILE (cfun->decl)
5845 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) == 0
5846 && !lang_hooks.function.missing_noreturn_ok_p (cfun->decl))
5847 warning ("%Jfunction might be possible candidate for "
5848 "attribute %<noreturn%>",
5851 /* If we have a path to EXIT, then we do return. */
5852 if (TREE_THIS_VOLATILE (cfun->decl)
5853 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) > 0)
5855 #ifdef USE_MAPPED_LOCATION
5856 location = UNKNOWN_LOCATION;
5860 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
5862 last = last_stmt (e->src);
5863 if (TREE_CODE (last) == RETURN_EXPR
5864 #ifdef USE_MAPPED_LOCATION
5865 && (location = EXPR_LOCATION (last)) != UNKNOWN_LOCATION)
5867 && (locus = EXPR_LOCUS (last)) != NULL)
5871 #ifdef USE_MAPPED_LOCATION
5872 if (location == UNKNOWN_LOCATION)
5873 location = cfun->function_end_locus;
5874 warning ("%H%<noreturn%> function does return", &location);
5877 locus = &cfun->function_end_locus;
5878 warning ("%H%<noreturn%> function does return", locus);
5882 /* If we see "return;" in some basic block, then we do reach the end
5883 without returning a value. */
5884 else if (warn_return_type
5885 && !TREE_NO_WARNING (cfun->decl)
5886 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) > 0
5887 && !VOID_TYPE_P (TREE_TYPE (TREE_TYPE (cfun->decl))))
5889 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
5891 tree last = last_stmt (e->src);
5892 if (TREE_CODE (last) == RETURN_EXPR
5893 && TREE_OPERAND (last, 0) == NULL)
5895 #ifdef USE_MAPPED_LOCATION
5896 location = EXPR_LOCATION (last);
5897 if (location == UNKNOWN_LOCATION)
5898 location = cfun->function_end_locus;
5899 warning ("%Hcontrol reaches end of non-void function", &location);
5901 locus = EXPR_LOCUS (last);
5903 locus = &cfun->function_end_locus;
5904 warning ("%Hcontrol reaches end of non-void function", locus);
5906 TREE_NO_WARNING (cfun->decl) = 1;
5914 /* Given a basic block B which ends with a conditional and has
5915 precisely two successors, determine which of the edges is taken if
5916 the conditional is true and which is taken if the conditional is
5917 false. Set TRUE_EDGE and FALSE_EDGE appropriately. */
5920 extract_true_false_edges_from_block (basic_block b,
5924 edge e = EDGE_SUCC (b, 0);
5926 if (e->flags & EDGE_TRUE_VALUE)
5929 *false_edge = EDGE_SUCC (b, 1);
5934 *true_edge = EDGE_SUCC (b, 1);
5938 struct tree_opt_pass pass_warn_function_return =
5942 execute_warn_function_return, /* execute */
5945 0, /* static_pass_number */
5947 PROP_cfg, /* properties_required */
5948 0, /* properties_provided */
5949 0, /* properties_destroyed */
5950 0, /* todo_flags_start */
5951 0, /* todo_flags_finish */
5955 #include "gt-tree-cfg.h"