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 (!single_succ_p (a))
1266 if (single_succ_edge (a)->flags & EDGE_ABNORMAL)
1269 if (single_succ (a) != b)
1272 if (!single_pred_p (b))
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 (single_succ_edge (a)->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 (!single_pred_p (bb)
1926 || !(single_pred_edge (bb)->flags
1927 & (EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
1930 cond = COND_EXPR_COND (last_stmt (single_pred (bb)));
1932 if (TREE_CODE (cond) == VAR_DECL || TREE_CODE (cond) == PARM_DECL)
1935 val = (single_pred_edge (bb)->flags & EDGE_FALSE_VALUE
1936 ? boolean_false_node : boolean_true_node);
1938 else if (TREE_CODE (cond) == TRUTH_NOT_EXPR
1939 && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL
1940 || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL))
1942 var = TREE_OPERAND (cond, 0);
1943 val = (single_pred_edge (bb)->flags & EDGE_FALSE_VALUE
1944 ? boolean_true_node : boolean_false_node);
1948 if (single_pred_edge (bb)->flags & EDGE_FALSE_VALUE)
1949 cond = invert_truthvalue (cond);
1950 if (TREE_CODE (cond) == EQ_EXPR
1951 && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL
1952 || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL)
1953 && (TREE_CODE (TREE_OPERAND (cond, 1)) == VAR_DECL
1954 || TREE_CODE (TREE_OPERAND (cond, 1)) == PARM_DECL
1955 || TREE_CONSTANT (TREE_OPERAND (cond, 1))))
1957 var = TREE_OPERAND (cond, 0);
1958 val = TREE_OPERAND (cond, 1);
1964 /* Only work for normal local variables. */
1965 ann = var_ann (var);
1968 || TREE_ADDRESSABLE (var))
1971 if (! TREE_CONSTANT (val))
1973 ann = var_ann (val);
1976 || TREE_ADDRESSABLE (val))
1980 /* Ignore floating point variables, since comparison behaves weird for
1982 if (FLOAT_TYPE_P (TREE_TYPE (var)))
1985 for (bsi = bsi_start (bb); !bsi_end_p (bsi);)
1987 stmt = bsi_stmt (bsi);
1989 /* If the THEN/ELSE clause merely assigns a value to a variable/parameter
1990 which is already known to contain that value, then remove the useless
1991 THEN/ELSE clause. */
1992 if (TREE_CODE (stmt) == MODIFY_EXPR
1993 && TREE_OPERAND (stmt, 0) == var
1994 && operand_equal_p (val, TREE_OPERAND (stmt, 1), 0))
2000 /* Invalidate the var if we encounter something that could modify it.
2001 Likewise for the value it was previously set to. Note that we only
2002 consider values that are either a VAR_DECL or PARM_DECL so we
2003 can test for conflict very simply. */
2004 if (TREE_CODE (stmt) == ASM_EXPR
2005 || (TREE_CODE (stmt) == MODIFY_EXPR
2006 && (TREE_OPERAND (stmt, 0) == var
2007 || TREE_OPERAND (stmt, 0) == val)))
2015 /* A CFG-aware version of remove_useless_stmts. */
2018 cfg_remove_useless_stmts (void)
2022 #ifdef ENABLE_CHECKING
2023 verify_flow_info ();
2028 cfg_remove_useless_stmts_bb (bb);
2033 /* Remove PHI nodes associated with basic block BB and all edges out of BB. */
2036 remove_phi_nodes_and_edges_for_unreachable_block (basic_block bb)
2040 /* Since this block is no longer reachable, we can just delete all
2041 of its PHI nodes. */
2042 phi = phi_nodes (bb);
2045 tree next = PHI_CHAIN (phi);
2046 remove_phi_node (phi, NULL_TREE);
2050 /* Remove edges to BB's successors. */
2051 while (EDGE_COUNT (bb->succs) > 0)
2052 remove_edge (EDGE_SUCC (bb, 0));
2056 /* Remove statements of basic block BB. */
2059 remove_bb (basic_block bb)
2061 block_stmt_iterator i;
2062 #ifdef USE_MAPPED_LOCATION
2063 source_location loc = UNKNOWN_LOCATION;
2065 source_locus loc = 0;
2070 fprintf (dump_file, "Removing basic block %d\n", bb->index);
2071 if (dump_flags & TDF_DETAILS)
2073 dump_bb (bb, dump_file, 0);
2074 fprintf (dump_file, "\n");
2078 /* If we remove the header or the latch of a loop, mark the loop for
2079 removal by setting its header and latch to NULL. */
2082 struct loop *loop = bb->loop_father;
2084 if (loop->latch == bb
2085 || loop->header == bb)
2088 loop->header = NULL;
2092 /* Remove all the instructions in the block. */
2093 for (i = bsi_start (bb); !bsi_end_p (i);)
2095 tree stmt = bsi_stmt (i);
2096 if (TREE_CODE (stmt) == LABEL_EXPR
2097 && FORCED_LABEL (LABEL_EXPR_LABEL (stmt)))
2099 basic_block new_bb = bb->prev_bb;
2100 block_stmt_iterator new_bsi = bsi_start (new_bb);
2103 bsi_insert_before (&new_bsi, stmt, BSI_NEW_STMT);
2107 release_defs (stmt);
2109 set_bb_for_stmt (stmt, NULL);
2113 /* Don't warn for removed gotos. Gotos are often removed due to
2114 jump threading, thus resulting in bogus warnings. Not great,
2115 since this way we lose warnings for gotos in the original
2116 program that are indeed unreachable. */
2117 if (TREE_CODE (stmt) != GOTO_EXPR && EXPR_HAS_LOCATION (stmt) && !loc)
2119 #ifdef USE_MAPPED_LOCATION
2120 if (EXPR_HAS_LOCATION (stmt))
2121 loc = EXPR_LOCATION (stmt);
2124 t = EXPR_LOCUS (stmt);
2125 if (t && LOCATION_LINE (*t) > 0)
2131 /* If requested, give a warning that the first statement in the
2132 block is unreachable. We walk statements backwards in the
2133 loop above, so the last statement we process is the first statement
2135 #ifdef USE_MAPPED_LOCATION
2136 if (warn_notreached && loc != UNKNOWN_LOCATION)
2137 warning ("%Hwill never be executed", &loc);
2139 if (warn_notreached && loc)
2140 warning ("%Hwill never be executed", loc);
2143 remove_phi_nodes_and_edges_for_unreachable_block (bb);
2146 /* A list of all the noreturn calls passed to modify_stmt.
2147 cleanup_control_flow uses it to detect cases where a mid-block
2148 indirect call has been turned into a noreturn call. When this
2149 happens, all the instructions after the call are no longer
2150 reachable and must be deleted as dead. */
2152 VEC(tree) *modified_noreturn_calls;
2154 /* Try to remove superfluous control structures. */
2157 cleanup_control_flow (void)
2160 block_stmt_iterator bsi;
2161 bool retval = false;
2164 /* Detect cases where a mid-block call is now known not to return. */
2165 while (VEC_length (tree, modified_noreturn_calls))
2167 stmt = VEC_pop (tree, modified_noreturn_calls);
2168 bb = bb_for_stmt (stmt);
2169 if (bb != NULL && last_stmt (bb) != stmt && noreturn_call_p (stmt))
2170 split_block (bb, stmt);
2175 bsi = bsi_last (bb);
2177 if (bsi_end_p (bsi))
2180 stmt = bsi_stmt (bsi);
2181 if (TREE_CODE (stmt) == COND_EXPR
2182 || TREE_CODE (stmt) == SWITCH_EXPR)
2183 retval |= cleanup_control_expr_graph (bb, bsi);
2185 /* If we had a computed goto which has a compile-time determinable
2186 destination, then we can eliminate the goto. */
2187 if (TREE_CODE (stmt) == GOTO_EXPR
2188 && TREE_CODE (GOTO_DESTINATION (stmt)) == ADDR_EXPR
2189 && TREE_CODE (TREE_OPERAND (GOTO_DESTINATION (stmt), 0)) == LABEL_DECL)
2194 basic_block target_block;
2195 bool removed_edge = false;
2197 /* First look at all the outgoing edges. Delete any outgoing
2198 edges which do not go to the right block. For the one
2199 edge which goes to the right block, fix up its flags. */
2200 label = TREE_OPERAND (GOTO_DESTINATION (stmt), 0);
2201 target_block = label_to_block (label);
2202 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2204 if (e->dest != target_block)
2206 removed_edge = true;
2211 /* Turn off the EDGE_ABNORMAL flag. */
2212 e->flags &= ~EDGE_ABNORMAL;
2214 /* And set EDGE_FALLTHRU. */
2215 e->flags |= EDGE_FALLTHRU;
2220 /* If we removed one or more edges, then we will need to fix the
2221 dominators. It may be possible to incrementally update them. */
2223 free_dominance_info (CDI_DOMINATORS);
2225 /* Remove the GOTO_EXPR as it is not needed. The CFG has all the
2226 relevant information we need. */
2231 /* Check for indirect calls that have been turned into
2233 if (noreturn_call_p (stmt) && remove_fallthru_edge (bb->succs))
2235 free_dominance_info (CDI_DOMINATORS);
2243 /* Disconnect an unreachable block in the control expression starting
2247 cleanup_control_expr_graph (basic_block bb, block_stmt_iterator bsi)
2250 bool retval = false;
2251 tree expr = bsi_stmt (bsi), val;
2253 if (!single_succ_p (bb))
2258 switch (TREE_CODE (expr))
2261 val = COND_EXPR_COND (expr);
2265 val = SWITCH_COND (expr);
2266 if (TREE_CODE (val) != INTEGER_CST)
2274 taken_edge = find_taken_edge (bb, val);
2278 /* Remove all the edges except the one that is always executed. */
2279 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2281 if (e != taken_edge)
2283 taken_edge->probability += e->probability;
2284 taken_edge->count += e->count;
2291 if (taken_edge->probability > REG_BR_PROB_BASE)
2292 taken_edge->probability = REG_BR_PROB_BASE;
2295 taken_edge = single_succ_edge (bb);
2298 taken_edge->flags = EDGE_FALLTHRU;
2300 /* We removed some paths from the cfg. */
2301 free_dominance_info (CDI_DOMINATORS);
2306 /* Remove any fallthru edge from EV. Return true if an edge was removed. */
2309 remove_fallthru_edge (VEC(edge) *ev)
2314 FOR_EACH_EDGE (e, ei, ev)
2315 if ((e->flags & EDGE_FALLTHRU) != 0)
2323 /* Given a basic block BB ending with COND_EXPR or SWITCH_EXPR, and a
2324 predicate VAL, return the edge that will be taken out of the block.
2325 If VAL does not match a unique edge, NULL is returned. */
2328 find_taken_edge (basic_block bb, tree val)
2332 stmt = last_stmt (bb);
2335 gcc_assert (is_ctrl_stmt (stmt));
2338 if (! is_gimple_min_invariant (val))
2341 if (TREE_CODE (stmt) == COND_EXPR)
2342 return find_taken_edge_cond_expr (bb, val);
2344 if (TREE_CODE (stmt) == SWITCH_EXPR)
2345 return find_taken_edge_switch_expr (bb, val);
2347 if (computed_goto_p (stmt))
2348 return find_taken_edge_computed_goto (bb, TREE_OPERAND( val, 0));
2353 /* Given a constant value VAL and the entry block BB to a GOTO_EXPR
2354 statement, determine which of the outgoing edges will be taken out of the
2355 block. Return NULL if either edge may be taken. */
2358 find_taken_edge_computed_goto (basic_block bb, tree val)
2363 dest = label_to_block (val);
2366 e = find_edge (bb, dest);
2367 gcc_assert (e != NULL);
2373 /* Given a constant value VAL and the entry block BB to a COND_EXPR
2374 statement, determine which of the two edges will be taken out of the
2375 block. Return NULL if either edge may be taken. */
2378 find_taken_edge_cond_expr (basic_block bb, tree val)
2380 edge true_edge, false_edge;
2382 extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
2384 /* Otherwise, try to determine which branch of the if() will be taken.
2385 If VAL is a constant but it can't be reduced to a 0 or a 1, then
2386 we don't really know which edge will be taken at runtime. This
2387 may happen when comparing addresses (e.g., if (&var1 == 4)). */
2388 if (integer_nonzerop (val))
2390 else if (integer_zerop (val))
2397 /* Given an INTEGER_CST VAL and the entry block BB to a SWITCH_EXPR
2398 statement, determine which edge will be taken out of the block. Return
2399 NULL if any edge may be taken. */
2402 find_taken_edge_switch_expr (basic_block bb, tree val)
2404 tree switch_expr, taken_case;
2405 basic_block dest_bb;
2408 switch_expr = last_stmt (bb);
2409 taken_case = find_case_label_for_value (switch_expr, val);
2410 dest_bb = label_to_block (CASE_LABEL (taken_case));
2412 e = find_edge (bb, dest_bb);
2418 /* Return the CASE_LABEL_EXPR that SWITCH_EXPR will take for VAL.
2419 We can make optimal use here of the fact that the case labels are
2420 sorted: We can do a binary search for a case matching VAL. */
2423 find_case_label_for_value (tree switch_expr, tree val)
2425 tree vec = SWITCH_LABELS (switch_expr);
2426 size_t low, high, n = TREE_VEC_LENGTH (vec);
2427 tree default_case = TREE_VEC_ELT (vec, n - 1);
2429 for (low = -1, high = n - 1; high - low > 1; )
2431 size_t i = (high + low) / 2;
2432 tree t = TREE_VEC_ELT (vec, i);
2435 /* Cache the result of comparing CASE_LOW and val. */
2436 cmp = tree_int_cst_compare (CASE_LOW (t), val);
2443 if (CASE_HIGH (t) == NULL)
2445 /* A singe-valued case label. */
2451 /* A case range. We can only handle integer ranges. */
2452 if (cmp <= 0 && tree_int_cst_compare (CASE_HIGH (t), val) >= 0)
2457 return default_case;
2461 /* If all the PHI nodes in DEST have alternatives for E1 and E2 and
2462 those alternatives are equal in each of the PHI nodes, then return
2463 true, else return false. */
2466 phi_alternatives_equal (basic_block dest, edge e1, edge e2)
2468 int n1 = e1->dest_idx;
2469 int n2 = e2->dest_idx;
2472 for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi))
2474 tree val1 = PHI_ARG_DEF (phi, n1);
2475 tree val2 = PHI_ARG_DEF (phi, n2);
2477 gcc_assert (val1 != NULL_TREE);
2478 gcc_assert (val2 != NULL_TREE);
2480 if (!operand_equal_for_phi_arg_p (val1, val2))
2488 /*---------------------------------------------------------------------------
2490 ---------------------------------------------------------------------------*/
2492 /* Dump tree-specific information of block BB to file OUTF. */
2495 tree_dump_bb (basic_block bb, FILE *outf, int indent)
2497 dump_generic_bb (outf, bb, indent, TDF_VOPS);
2501 /* Dump a basic block on stderr. */
2504 debug_tree_bb (basic_block bb)
2506 dump_bb (bb, stderr, 0);
2510 /* Dump basic block with index N on stderr. */
2513 debug_tree_bb_n (int n)
2515 debug_tree_bb (BASIC_BLOCK (n));
2516 return BASIC_BLOCK (n);
2520 /* Dump the CFG on stderr.
2522 FLAGS are the same used by the tree dumping functions
2523 (see TDF_* in tree.h). */
2526 debug_tree_cfg (int flags)
2528 dump_tree_cfg (stderr, flags);
2532 /* Dump the program showing basic block boundaries on the given FILE.
2534 FLAGS are the same used by the tree dumping functions (see TDF_* in
2538 dump_tree_cfg (FILE *file, int flags)
2540 if (flags & TDF_DETAILS)
2542 const char *funcname
2543 = lang_hooks.decl_printable_name (current_function_decl, 2);
2546 fprintf (file, ";; Function %s\n\n", funcname);
2547 fprintf (file, ";; \n%d basic blocks, %d edges, last basic block %d.\n\n",
2548 n_basic_blocks, n_edges, last_basic_block);
2550 brief_dump_cfg (file);
2551 fprintf (file, "\n");
2554 if (flags & TDF_STATS)
2555 dump_cfg_stats (file);
2557 dump_function_to_file (current_function_decl, file, flags | TDF_BLOCKS);
2561 /* Dump CFG statistics on FILE. */
2564 dump_cfg_stats (FILE *file)
2566 static long max_num_merged_labels = 0;
2567 unsigned long size, total = 0;
2570 const char * const fmt_str = "%-30s%-13s%12s\n";
2571 const char * const fmt_str_1 = "%-30s%13d%11lu%c\n";
2572 const char * const fmt_str_3 = "%-43s%11lu%c\n";
2573 const char *funcname
2574 = lang_hooks.decl_printable_name (current_function_decl, 2);
2577 fprintf (file, "\nCFG Statistics for %s\n\n", funcname);
2579 fprintf (file, "---------------------------------------------------------\n");
2580 fprintf (file, fmt_str, "", " Number of ", "Memory");
2581 fprintf (file, fmt_str, "", " instances ", "used ");
2582 fprintf (file, "---------------------------------------------------------\n");
2584 size = n_basic_blocks * sizeof (struct basic_block_def);
2586 fprintf (file, fmt_str_1, "Basic blocks", n_basic_blocks,
2587 SCALE (size), LABEL (size));
2591 n_edges += EDGE_COUNT (bb->succs);
2592 size = n_edges * sizeof (struct edge_def);
2594 fprintf (file, fmt_str_1, "Edges", n_edges, SCALE (size), LABEL (size));
2596 size = n_basic_blocks * sizeof (struct bb_ann_d);
2598 fprintf (file, fmt_str_1, "Basic block annotations", n_basic_blocks,
2599 SCALE (size), LABEL (size));
2601 fprintf (file, "---------------------------------------------------------\n");
2602 fprintf (file, fmt_str_3, "Total memory used by CFG data", SCALE (total),
2604 fprintf (file, "---------------------------------------------------------\n");
2605 fprintf (file, "\n");
2607 if (cfg_stats.num_merged_labels > max_num_merged_labels)
2608 max_num_merged_labels = cfg_stats.num_merged_labels;
2610 fprintf (file, "Coalesced label blocks: %ld (Max so far: %ld)\n",
2611 cfg_stats.num_merged_labels, max_num_merged_labels);
2613 fprintf (file, "\n");
2617 /* Dump CFG statistics on stderr. Keep extern so that it's always
2618 linked in the final executable. */
2621 debug_cfg_stats (void)
2623 dump_cfg_stats (stderr);
2627 /* Dump the flowgraph to a .vcg FILE. */
2630 tree_cfg2vcg (FILE *file)
2635 const char *funcname
2636 = lang_hooks.decl_printable_name (current_function_decl, 2);
2638 /* Write the file header. */
2639 fprintf (file, "graph: { title: \"%s\"\n", funcname);
2640 fprintf (file, "node: { title: \"ENTRY\" label: \"ENTRY\" }\n");
2641 fprintf (file, "node: { title: \"EXIT\" label: \"EXIT\" }\n");
2643 /* Write blocks and edges. */
2644 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
2646 fprintf (file, "edge: { sourcename: \"ENTRY\" targetname: \"%d\"",
2649 if (e->flags & EDGE_FAKE)
2650 fprintf (file, " linestyle: dotted priority: 10");
2652 fprintf (file, " linestyle: solid priority: 100");
2654 fprintf (file, " }\n");
2660 enum tree_code head_code, end_code;
2661 const char *head_name, *end_name;
2664 tree first = first_stmt (bb);
2665 tree last = last_stmt (bb);
2669 head_code = TREE_CODE (first);
2670 head_name = tree_code_name[head_code];
2671 head_line = get_lineno (first);
2674 head_name = "no-statement";
2678 end_code = TREE_CODE (last);
2679 end_name = tree_code_name[end_code];
2680 end_line = get_lineno (last);
2683 end_name = "no-statement";
2685 fprintf (file, "node: { title: \"%d\" label: \"#%d\\n%s (%d)\\n%s (%d)\"}\n",
2686 bb->index, bb->index, head_name, head_line, end_name,
2689 FOR_EACH_EDGE (e, ei, bb->succs)
2691 if (e->dest == EXIT_BLOCK_PTR)
2692 fprintf (file, "edge: { sourcename: \"%d\" targetname: \"EXIT\"", bb->index);
2694 fprintf (file, "edge: { sourcename: \"%d\" targetname: \"%d\"", bb->index, e->dest->index);
2696 if (e->flags & EDGE_FAKE)
2697 fprintf (file, " priority: 10 linestyle: dotted");
2699 fprintf (file, " priority: 100 linestyle: solid");
2701 fprintf (file, " }\n");
2704 if (bb->next_bb != EXIT_BLOCK_PTR)
2708 fputs ("}\n\n", file);
2713 /*---------------------------------------------------------------------------
2714 Miscellaneous helpers
2715 ---------------------------------------------------------------------------*/
2717 /* Return true if T represents a stmt that always transfers control. */
2720 is_ctrl_stmt (tree t)
2722 return (TREE_CODE (t) == COND_EXPR
2723 || TREE_CODE (t) == SWITCH_EXPR
2724 || TREE_CODE (t) == GOTO_EXPR
2725 || TREE_CODE (t) == RETURN_EXPR
2726 || TREE_CODE (t) == RESX_EXPR);
2730 /* Return true if T is a statement that may alter the flow of control
2731 (e.g., a call to a non-returning function). */
2734 is_ctrl_altering_stmt (tree t)
2739 call = get_call_expr_in (t);
2742 /* A non-pure/const CALL_EXPR alters flow control if the current
2743 function has nonlocal labels. */
2744 if (TREE_SIDE_EFFECTS (call) && current_function_has_nonlocal_label)
2747 /* A CALL_EXPR also alters control flow if it does not return. */
2748 if (call_expr_flags (call) & ECF_NORETURN)
2752 /* If a statement can throw, it alters control flow. */
2753 return tree_can_throw_internal (t);
2757 /* Return true if T is a computed goto. */
2760 computed_goto_p (tree t)
2762 return (TREE_CODE (t) == GOTO_EXPR
2763 && TREE_CODE (GOTO_DESTINATION (t)) != LABEL_DECL);
2767 /* Checks whether EXPR is a simple local goto. */
2770 simple_goto_p (tree expr)
2772 return (TREE_CODE (expr) == GOTO_EXPR
2773 && TREE_CODE (GOTO_DESTINATION (expr)) == LABEL_DECL);
2777 /* Return true if T should start a new basic block. PREV_T is the
2778 statement preceding T. It is used when T is a label or a case label.
2779 Labels should only start a new basic block if their previous statement
2780 wasn't a label. Otherwise, sequence of labels would generate
2781 unnecessary basic blocks that only contain a single label. */
2784 stmt_starts_bb_p (tree t, tree prev_t)
2789 /* LABEL_EXPRs start a new basic block only if the preceding
2790 statement wasn't a label of the same type. This prevents the
2791 creation of consecutive blocks that have nothing but a single
2793 if (TREE_CODE (t) == LABEL_EXPR)
2795 /* Nonlocal and computed GOTO targets always start a new block. */
2796 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (t))
2797 || FORCED_LABEL (LABEL_EXPR_LABEL (t)))
2800 if (prev_t && TREE_CODE (prev_t) == LABEL_EXPR)
2802 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (prev_t)))
2805 cfg_stats.num_merged_labels++;
2816 /* Return true if T should end a basic block. */
2819 stmt_ends_bb_p (tree t)
2821 return is_ctrl_stmt (t) || is_ctrl_altering_stmt (t);
2825 /* Add gotos that used to be represented implicitly in the CFG. */
2828 disband_implicit_edges (void)
2831 block_stmt_iterator last;
2838 last = bsi_last (bb);
2839 stmt = last_stmt (bb);
2841 if (stmt && TREE_CODE (stmt) == COND_EXPR)
2843 /* Remove superfluous gotos from COND_EXPR branches. Moved
2844 from cfg_remove_useless_stmts here since it violates the
2845 invariants for tree--cfg correspondence and thus fits better
2846 here where we do it anyway. */
2847 e = find_edge (bb, bb->next_bb);
2850 if (e->flags & EDGE_TRUE_VALUE)
2851 COND_EXPR_THEN (stmt) = build_empty_stmt ();
2852 else if (e->flags & EDGE_FALSE_VALUE)
2853 COND_EXPR_ELSE (stmt) = build_empty_stmt ();
2856 e->flags |= EDGE_FALLTHRU;
2862 if (stmt && TREE_CODE (stmt) == RETURN_EXPR)
2864 /* Remove the RETURN_EXPR if we may fall though to the exit
2866 gcc_assert (single_succ_p (bb));
2867 gcc_assert (single_succ (bb) == EXIT_BLOCK_PTR);
2869 if (bb->next_bb == EXIT_BLOCK_PTR
2870 && !TREE_OPERAND (stmt, 0))
2873 single_succ_edge (bb)->flags |= EDGE_FALLTHRU;
2878 /* There can be no fallthru edge if the last statement is a control
2880 if (stmt && is_ctrl_stmt (stmt))
2883 /* Find a fallthru edge and emit the goto if necessary. */
2884 FOR_EACH_EDGE (e, ei, bb->succs)
2885 if (e->flags & EDGE_FALLTHRU)
2888 if (!e || e->dest == bb->next_bb)
2891 gcc_assert (e->dest != EXIT_BLOCK_PTR);
2892 label = tree_block_label (e->dest);
2894 stmt = build1 (GOTO_EXPR, void_type_node, label);
2895 #ifdef USE_MAPPED_LOCATION
2896 SET_EXPR_LOCATION (stmt, e->goto_locus);
2898 SET_EXPR_LOCUS (stmt, e->goto_locus);
2900 bsi_insert_after (&last, stmt, BSI_NEW_STMT);
2901 e->flags &= ~EDGE_FALLTHRU;
2905 /* Remove block annotations and other datastructures. */
2908 delete_tree_cfg_annotations (void)
2911 if (n_basic_blocks > 0)
2912 free_blocks_annotations ();
2914 label_to_block_map = NULL;
2921 /* Return the first statement in basic block BB. */
2924 first_stmt (basic_block bb)
2926 block_stmt_iterator i = bsi_start (bb);
2927 return !bsi_end_p (i) ? bsi_stmt (i) : NULL_TREE;
2931 /* Return the last statement in basic block BB. */
2934 last_stmt (basic_block bb)
2936 block_stmt_iterator b = bsi_last (bb);
2937 return !bsi_end_p (b) ? bsi_stmt (b) : NULL_TREE;
2941 /* Return a pointer to the last statement in block BB. */
2944 last_stmt_ptr (basic_block bb)
2946 block_stmt_iterator last = bsi_last (bb);
2947 return !bsi_end_p (last) ? bsi_stmt_ptr (last) : NULL;
2951 /* Return the last statement of an otherwise empty block. Return NULL
2952 if the block is totally empty, or if it contains more than one
2956 last_and_only_stmt (basic_block bb)
2958 block_stmt_iterator i = bsi_last (bb);
2964 last = bsi_stmt (i);
2969 /* Empty statements should no longer appear in the instruction stream.
2970 Everything that might have appeared before should be deleted by
2971 remove_useless_stmts, and the optimizers should just bsi_remove
2972 instead of smashing with build_empty_stmt.
2974 Thus the only thing that should appear here in a block containing
2975 one executable statement is a label. */
2976 prev = bsi_stmt (i);
2977 if (TREE_CODE (prev) == LABEL_EXPR)
2984 /* Mark BB as the basic block holding statement T. */
2987 set_bb_for_stmt (tree t, basic_block bb)
2989 if (TREE_CODE (t) == PHI_NODE)
2991 else if (TREE_CODE (t) == STATEMENT_LIST)
2993 tree_stmt_iterator i;
2994 for (i = tsi_start (t); !tsi_end_p (i); tsi_next (&i))
2995 set_bb_for_stmt (tsi_stmt (i), bb);
2999 stmt_ann_t ann = get_stmt_ann (t);
3002 /* If the statement is a label, add the label to block-to-labels map
3003 so that we can speed up edge creation for GOTO_EXPRs. */
3004 if (TREE_CODE (t) == LABEL_EXPR)
3008 t = LABEL_EXPR_LABEL (t);
3009 uid = LABEL_DECL_UID (t);
3012 LABEL_DECL_UID (t) = uid = cfun->last_label_uid++;
3013 if (VARRAY_SIZE (label_to_block_map) <= (unsigned) uid)
3014 VARRAY_GROW (label_to_block_map, 3 * uid / 2);
3017 /* We're moving an existing label. Make sure that we've
3018 removed it from the old block. */
3019 gcc_assert (!bb || !VARRAY_BB (label_to_block_map, uid));
3020 VARRAY_BB (label_to_block_map, uid) = bb;
3025 /* Finds iterator for STMT. */
3027 extern block_stmt_iterator
3028 bsi_for_stmt (tree stmt)
3030 block_stmt_iterator bsi;
3032 for (bsi = bsi_start (bb_for_stmt (stmt)); !bsi_end_p (bsi); bsi_next (&bsi))
3033 if (bsi_stmt (bsi) == stmt)
3039 /* Insert statement (or statement list) T before the statement
3040 pointed-to by iterator I. M specifies how to update iterator I
3041 after insertion (see enum bsi_iterator_update). */
3044 bsi_insert_before (block_stmt_iterator *i, tree t, enum bsi_iterator_update m)
3046 set_bb_for_stmt (t, i->bb);
3047 tsi_link_before (&i->tsi, t, m);
3052 /* Insert statement (or statement list) T after the statement
3053 pointed-to by iterator I. M specifies how to update iterator I
3054 after insertion (see enum bsi_iterator_update). */
3057 bsi_insert_after (block_stmt_iterator *i, tree t, enum bsi_iterator_update m)
3059 set_bb_for_stmt (t, i->bb);
3060 tsi_link_after (&i->tsi, t, m);
3065 /* Remove the statement pointed to by iterator I. The iterator is updated
3066 to the next statement. */
3069 bsi_remove (block_stmt_iterator *i)
3071 tree t = bsi_stmt (*i);
3072 set_bb_for_stmt (t, NULL);
3073 tsi_delink (&i->tsi);
3077 /* Move the statement at FROM so it comes right after the statement at TO. */
3080 bsi_move_after (block_stmt_iterator *from, block_stmt_iterator *to)
3082 tree stmt = bsi_stmt (*from);
3084 bsi_insert_after (to, stmt, BSI_SAME_STMT);
3088 /* Move the statement at FROM so it comes right before the statement at TO. */
3091 bsi_move_before (block_stmt_iterator *from, block_stmt_iterator *to)
3093 tree stmt = bsi_stmt (*from);
3095 bsi_insert_before (to, stmt, BSI_SAME_STMT);
3099 /* Move the statement at FROM to the end of basic block BB. */
3102 bsi_move_to_bb_end (block_stmt_iterator *from, basic_block bb)
3104 block_stmt_iterator last = bsi_last (bb);
3106 /* Have to check bsi_end_p because it could be an empty block. */
3107 if (!bsi_end_p (last) && is_ctrl_stmt (bsi_stmt (last)))
3108 bsi_move_before (from, &last);
3110 bsi_move_after (from, &last);
3114 /* Replace the contents of the statement pointed to by iterator BSI
3115 with STMT. If PRESERVE_EH_INFO is true, the exception handling
3116 information of the original statement is preserved. */
3119 bsi_replace (const block_stmt_iterator *bsi, tree stmt, bool preserve_eh_info)
3122 tree orig_stmt = bsi_stmt (*bsi);
3124 SET_EXPR_LOCUS (stmt, EXPR_LOCUS (orig_stmt));
3125 set_bb_for_stmt (stmt, bsi->bb);
3127 /* Preserve EH region information from the original statement, if
3128 requested by the caller. */
3129 if (preserve_eh_info)
3131 eh_region = lookup_stmt_eh_region (orig_stmt);
3133 add_stmt_to_eh_region (stmt, eh_region);
3136 *bsi_stmt_ptr (*bsi) = stmt;
3141 /* Insert the statement pointed-to by BSI into edge E. Every attempt
3142 is made to place the statement in an existing basic block, but
3143 sometimes that isn't possible. When it isn't possible, the edge is
3144 split and the statement is added to the new block.
3146 In all cases, the returned *BSI points to the correct location. The
3147 return value is true if insertion should be done after the location,
3148 or false if it should be done before the location. If new basic block
3149 has to be created, it is stored in *NEW_BB. */
3152 tree_find_edge_insert_loc (edge e, block_stmt_iterator *bsi,
3153 basic_block *new_bb)
3155 basic_block dest, src;
3161 /* If the destination has one predecessor which has no PHI nodes,
3162 insert there. Except for the exit block.
3164 The requirement for no PHI nodes could be relaxed. Basically we
3165 would have to examine the PHIs to prove that none of them used
3166 the value set by the statement we want to insert on E. That
3167 hardly seems worth the effort. */
3168 if (single_pred_p (dest)
3169 && ! phi_nodes (dest)
3170 && dest != EXIT_BLOCK_PTR)
3172 *bsi = bsi_start (dest);
3173 if (bsi_end_p (*bsi))
3176 /* Make sure we insert after any leading labels. */
3177 tmp = bsi_stmt (*bsi);
3178 while (TREE_CODE (tmp) == LABEL_EXPR)
3181 if (bsi_end_p (*bsi))
3183 tmp = bsi_stmt (*bsi);
3186 if (bsi_end_p (*bsi))
3188 *bsi = bsi_last (dest);
3195 /* If the source has one successor, the edge is not abnormal and
3196 the last statement does not end a basic block, insert there.
3197 Except for the entry block. */
3199 if ((e->flags & EDGE_ABNORMAL) == 0
3200 && single_succ_p (src)
3201 && src != ENTRY_BLOCK_PTR)
3203 *bsi = bsi_last (src);
3204 if (bsi_end_p (*bsi))
3207 tmp = bsi_stmt (*bsi);
3208 if (!stmt_ends_bb_p (tmp))
3211 /* Insert code just before returning the value. We may need to decompose
3212 the return in the case it contains non-trivial operand. */
3213 if (TREE_CODE (tmp) == RETURN_EXPR)
3215 tree op = TREE_OPERAND (tmp, 0);
3216 if (!is_gimple_val (op))
3218 gcc_assert (TREE_CODE (op) == MODIFY_EXPR);
3219 bsi_insert_before (bsi, op, BSI_NEW_STMT);
3220 TREE_OPERAND (tmp, 0) = TREE_OPERAND (op, 0);
3227 /* Otherwise, create a new basic block, and split this edge. */
3228 dest = split_edge (e);
3231 e = single_pred_edge (dest);
3236 /* This routine will commit all pending edge insertions, creating any new
3237 basic blocks which are necessary. */
3240 bsi_commit_edge_inserts (void)
3246 bsi_commit_one_edge_insert (single_succ_edge (ENTRY_BLOCK_PTR), NULL);
3249 FOR_EACH_EDGE (e, ei, bb->succs)
3250 bsi_commit_one_edge_insert (e, NULL);
3254 /* Commit insertions pending at edge E. If a new block is created, set NEW_BB
3255 to this block, otherwise set it to NULL. */
3258 bsi_commit_one_edge_insert (edge e, basic_block *new_bb)
3262 if (PENDING_STMT (e))
3264 block_stmt_iterator bsi;
3265 tree stmt = PENDING_STMT (e);
3267 PENDING_STMT (e) = NULL_TREE;
3269 if (tree_find_edge_insert_loc (e, &bsi, new_bb))
3270 bsi_insert_after (&bsi, stmt, BSI_NEW_STMT);
3272 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
3277 /* Add STMT to the pending list of edge E. No actual insertion is
3278 made until a call to bsi_commit_edge_inserts () is made. */
3281 bsi_insert_on_edge (edge e, tree stmt)
3283 append_to_statement_list (stmt, &PENDING_STMT (e));
3286 /* Similar to bsi_insert_on_edge+bsi_commit_edge_inserts. If a new
3287 block has to be created, it is returned. */
3290 bsi_insert_on_edge_immediate (edge e, tree stmt)
3292 block_stmt_iterator bsi;
3293 basic_block new_bb = NULL;
3295 gcc_assert (!PENDING_STMT (e));
3297 if (tree_find_edge_insert_loc (e, &bsi, &new_bb))
3298 bsi_insert_after (&bsi, stmt, BSI_NEW_STMT);
3300 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
3305 /*---------------------------------------------------------------------------
3306 Tree specific functions for CFG manipulation
3307 ---------------------------------------------------------------------------*/
3309 /* Reinstall those PHI arguments queued in OLD_EDGE to NEW_EDGE. */
3312 reinstall_phi_args (edge new_edge, edge old_edge)
3316 if (!PENDING_STMT (old_edge))
3319 for (var = PENDING_STMT (old_edge), phi = phi_nodes (new_edge->dest);
3321 var = TREE_CHAIN (var), phi = PHI_CHAIN (phi))
3323 tree result = TREE_PURPOSE (var);
3324 tree arg = TREE_VALUE (var);
3326 gcc_assert (result == PHI_RESULT (phi));
3328 add_phi_arg (phi, arg, new_edge);
3331 PENDING_STMT (old_edge) = NULL;
3334 /* Split a (typically critical) edge EDGE_IN. Return the new block.
3335 Abort on abnormal edges. */
3338 tree_split_edge (edge edge_in)
3340 basic_block new_bb, after_bb, dest, src;
3343 /* Abnormal edges cannot be split. */
3344 gcc_assert (!(edge_in->flags & EDGE_ABNORMAL));
3347 dest = edge_in->dest;
3349 /* Place the new block in the block list. Try to keep the new block
3350 near its "logical" location. This is of most help to humans looking
3351 at debugging dumps. */
3352 if (dest->prev_bb && find_edge (dest->prev_bb, dest))
3353 after_bb = edge_in->src;
3355 after_bb = dest->prev_bb;
3357 new_bb = create_empty_bb (after_bb);
3358 new_bb->frequency = EDGE_FREQUENCY (edge_in);
3359 new_bb->count = edge_in->count;
3360 new_edge = make_edge (new_bb, dest, EDGE_FALLTHRU);
3361 new_edge->probability = REG_BR_PROB_BASE;
3362 new_edge->count = edge_in->count;
3364 e = redirect_edge_and_branch (edge_in, new_bb);
3366 reinstall_phi_args (new_edge, e);
3372 /* Return true when BB has label LABEL in it. */
3375 has_label_p (basic_block bb, tree label)
3377 block_stmt_iterator bsi;
3379 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3381 tree stmt = bsi_stmt (bsi);
3383 if (TREE_CODE (stmt) != LABEL_EXPR)
3385 if (LABEL_EXPR_LABEL (stmt) == label)
3392 /* Callback for walk_tree, check that all elements with address taken are
3393 properly noticed as such. The DATA is an int* that is 1 if TP was seen
3394 inside a PHI node. */
3397 verify_expr (tree *tp, int *walk_subtrees, void *data ATTRIBUTE_UNUSED)
3400 bool in_phi = (data != NULL);
3405 /* Check operand N for being valid GIMPLE and give error MSG if not.
3406 We check for constants explicitly since they are not considered
3407 gimple invariants if they overflowed. */
3408 #define CHECK_OP(N, MSG) \
3409 do { if (!CONSTANT_CLASS_P (TREE_OPERAND (t, N)) \
3410 && !is_gimple_val (TREE_OPERAND (t, N))) \
3411 { error (MSG); return TREE_OPERAND (t, N); }} while (0)
3413 switch (TREE_CODE (t))
3416 if (SSA_NAME_IN_FREE_LIST (t))
3418 error ("SSA name in freelist but still referenced");
3424 x = TREE_OPERAND (t, 0);
3425 if (TREE_CODE (x) == BIT_FIELD_REF
3426 && is_gimple_reg (TREE_OPERAND (x, 0)))
3428 error ("GIMPLE register modified with BIT_FIELD_REF");
3434 /* ??? tree-ssa-alias.c may have overlooked dead PHI nodes, missing
3435 dead PHIs that take the address of something. But if the PHI
3436 result is dead, the fact that it takes the address of anything
3437 is irrelevant. Because we can not tell from here if a PHI result
3438 is dead, we just skip this check for PHIs altogether. This means
3439 we may be missing "valid" checks, but what can you do?
3440 This was PR19217. */
3444 /* Skip any references (they will be checked when we recurse down the
3445 tree) and ensure that any variable used as a prefix is marked
3447 for (x = TREE_OPERAND (t, 0);
3448 handled_component_p (x);
3449 x = TREE_OPERAND (x, 0))
3452 if (TREE_CODE (x) != VAR_DECL && TREE_CODE (x) != PARM_DECL)
3454 if (!TREE_ADDRESSABLE (x))
3456 error ("address taken, but ADDRESSABLE bit not set");
3462 x = COND_EXPR_COND (t);
3463 if (TREE_CODE (TREE_TYPE (x)) != BOOLEAN_TYPE)
3465 error ("non-boolean used in condition");
3472 case FIX_TRUNC_EXPR:
3474 case FIX_FLOOR_EXPR:
3475 case FIX_ROUND_EXPR:
3480 case NON_LVALUE_EXPR:
3481 case TRUTH_NOT_EXPR:
3482 CHECK_OP (0, "Invalid operand to unary operator");
3489 case ARRAY_RANGE_REF:
3491 case VIEW_CONVERT_EXPR:
3492 /* We have a nest of references. Verify that each of the operands
3493 that determine where to reference is either a constant or a variable,
3494 verify that the base is valid, and then show we've already checked
3496 while (handled_component_p (t))
3498 if (TREE_CODE (t) == COMPONENT_REF && TREE_OPERAND (t, 2))
3499 CHECK_OP (2, "Invalid COMPONENT_REF offset operator");
3500 else if (TREE_CODE (t) == ARRAY_REF
3501 || TREE_CODE (t) == ARRAY_RANGE_REF)
3503 CHECK_OP (1, "Invalid array index.");
3504 if (TREE_OPERAND (t, 2))
3505 CHECK_OP (2, "Invalid array lower bound.");
3506 if (TREE_OPERAND (t, 3))
3507 CHECK_OP (3, "Invalid array stride.");
3509 else if (TREE_CODE (t) == BIT_FIELD_REF)
3511 CHECK_OP (1, "Invalid operand to BIT_FIELD_REF");
3512 CHECK_OP (2, "Invalid operand to BIT_FIELD_REF");
3515 t = TREE_OPERAND (t, 0);
3518 if (!CONSTANT_CLASS_P (t) && !is_gimple_lvalue (t))
3520 error ("Invalid reference prefix.");
3532 case UNORDERED_EXPR:
3543 case TRUNC_DIV_EXPR:
3545 case FLOOR_DIV_EXPR:
3546 case ROUND_DIV_EXPR:
3547 case TRUNC_MOD_EXPR:
3549 case FLOOR_MOD_EXPR:
3550 case ROUND_MOD_EXPR:
3552 case EXACT_DIV_EXPR:
3562 CHECK_OP (0, "Invalid operand to binary operator");
3563 CHECK_OP (1, "Invalid operand to binary operator");
3575 /* Verify STMT, return true if STMT is not in GIMPLE form.
3576 TODO: Implement type checking. */
3579 verify_stmt (tree stmt, bool last_in_block)
3583 if (!is_gimple_stmt (stmt))
3585 error ("Is not a valid GIMPLE statement.");
3589 addr = walk_tree (&stmt, verify_expr, NULL, NULL);
3592 debug_generic_stmt (addr);
3596 /* If the statement is marked as part of an EH region, then it is
3597 expected that the statement could throw. Verify that when we
3598 have optimizations that simplify statements such that we prove
3599 that they cannot throw, that we update other data structures
3601 if (lookup_stmt_eh_region (stmt) >= 0)
3603 if (!tree_could_throw_p (stmt))
3605 error ("Statement marked for throw, but doesn%'t.");
3608 if (!last_in_block && tree_can_throw_internal (stmt))
3610 error ("Statement marked for throw in middle of block.");
3618 debug_generic_stmt (stmt);
3623 /* Return true when the T can be shared. */
3626 tree_node_can_be_shared (tree t)
3628 if (IS_TYPE_OR_DECL_P (t)
3629 /* We check for constants explicitly since they are not considered
3630 gimple invariants if they overflowed. */
3631 || CONSTANT_CLASS_P (t)
3632 || is_gimple_min_invariant (t)
3633 || TREE_CODE (t) == SSA_NAME
3634 || t == error_mark_node)
3637 if (TREE_CODE (t) == CASE_LABEL_EXPR)
3640 while (((TREE_CODE (t) == ARRAY_REF || TREE_CODE (t) == ARRAY_RANGE_REF)
3641 /* We check for constants explicitly since they are not considered
3642 gimple invariants if they overflowed. */
3643 && (CONSTANT_CLASS_P (TREE_OPERAND (t, 1))
3644 || is_gimple_min_invariant (TREE_OPERAND (t, 1))))
3645 || (TREE_CODE (t) == COMPONENT_REF
3646 || TREE_CODE (t) == REALPART_EXPR
3647 || TREE_CODE (t) == IMAGPART_EXPR))
3648 t = TREE_OPERAND (t, 0);
3657 /* Called via walk_trees. Verify tree sharing. */
3660 verify_node_sharing (tree * tp, int *walk_subtrees, void *data)
3662 htab_t htab = (htab_t) data;
3665 if (tree_node_can_be_shared (*tp))
3667 *walk_subtrees = false;
3671 slot = htab_find_slot (htab, *tp, INSERT);
3680 /* Verify the GIMPLE statement chain. */
3686 block_stmt_iterator bsi;
3691 timevar_push (TV_TREE_STMT_VERIFY);
3692 htab = htab_create (37, htab_hash_pointer, htab_eq_pointer, NULL);
3699 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
3701 int phi_num_args = PHI_NUM_ARGS (phi);
3703 for (i = 0; i < phi_num_args; i++)
3705 tree t = PHI_ARG_DEF (phi, i);
3708 /* Addressable variables do have SSA_NAMEs but they
3709 are not considered gimple values. */
3710 if (TREE_CODE (t) != SSA_NAME
3711 && TREE_CODE (t) != FUNCTION_DECL
3712 && !is_gimple_val (t))
3714 error ("PHI def is not a GIMPLE value");
3715 debug_generic_stmt (phi);
3716 debug_generic_stmt (t);
3720 addr = walk_tree (&t, verify_expr, (void *) 1, NULL);
3723 debug_generic_stmt (addr);
3727 addr = walk_tree (&t, verify_node_sharing, htab, NULL);
3730 error ("Incorrect sharing of tree nodes");
3731 debug_generic_stmt (phi);
3732 debug_generic_stmt (addr);
3738 for (bsi = bsi_start (bb); !bsi_end_p (bsi); )
3740 tree stmt = bsi_stmt (bsi);
3742 err |= verify_stmt (stmt, bsi_end_p (bsi));
3743 addr = walk_tree (&stmt, verify_node_sharing, htab, NULL);
3746 error ("Incorrect sharing of tree nodes");
3747 debug_generic_stmt (stmt);
3748 debug_generic_stmt (addr);
3755 internal_error ("verify_stmts failed.");
3758 timevar_pop (TV_TREE_STMT_VERIFY);
3762 /* Verifies that the flow information is OK. */
3765 tree_verify_flow_info (void)
3769 block_stmt_iterator bsi;
3774 if (ENTRY_BLOCK_PTR->stmt_list)
3776 error ("ENTRY_BLOCK has a statement list associated with it\n");
3780 if (EXIT_BLOCK_PTR->stmt_list)
3782 error ("EXIT_BLOCK has a statement list associated with it\n");
3786 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
3787 if (e->flags & EDGE_FALLTHRU)
3789 error ("Fallthru to exit from bb %d\n", e->src->index);
3795 bool found_ctrl_stmt = false;
3799 /* Skip labels on the start of basic block. */
3800 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3802 tree prev_stmt = stmt;
3804 stmt = bsi_stmt (bsi);
3806 if (TREE_CODE (stmt) != LABEL_EXPR)
3809 if (prev_stmt && DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)))
3811 error ("Nonlocal label %s is not first "
3812 "in a sequence of labels in bb %d",
3813 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt))),
3818 if (label_to_block (LABEL_EXPR_LABEL (stmt)) != bb)
3820 error ("Label %s to block does not match in bb %d\n",
3821 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt))),
3826 if (decl_function_context (LABEL_EXPR_LABEL (stmt))
3827 != current_function_decl)
3829 error ("Label %s has incorrect context in bb %d\n",
3830 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt))),
3836 /* Verify that body of basic block BB is free of control flow. */
3837 for (; !bsi_end_p (bsi); bsi_next (&bsi))
3839 tree stmt = bsi_stmt (bsi);
3841 if (found_ctrl_stmt)
3843 error ("Control flow in the middle of basic block %d\n",
3848 if (stmt_ends_bb_p (stmt))
3849 found_ctrl_stmt = true;
3851 if (TREE_CODE (stmt) == LABEL_EXPR)
3853 error ("Label %s in the middle of basic block %d\n",
3854 IDENTIFIER_POINTER (DECL_NAME (stmt)),
3859 bsi = bsi_last (bb);
3860 if (bsi_end_p (bsi))
3863 stmt = bsi_stmt (bsi);
3865 if (is_ctrl_stmt (stmt))
3867 FOR_EACH_EDGE (e, ei, bb->succs)
3868 if (e->flags & EDGE_FALLTHRU)
3870 error ("Fallthru edge after a control statement in bb %d \n",
3876 switch (TREE_CODE (stmt))
3882 if (TREE_CODE (COND_EXPR_THEN (stmt)) != GOTO_EXPR
3883 || TREE_CODE (COND_EXPR_ELSE (stmt)) != GOTO_EXPR)
3885 error ("Structured COND_EXPR at the end of bb %d\n", bb->index);
3889 extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
3891 if (!true_edge || !false_edge
3892 || !(true_edge->flags & EDGE_TRUE_VALUE)
3893 || !(false_edge->flags & EDGE_FALSE_VALUE)
3894 || (true_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL))
3895 || (false_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL))
3896 || EDGE_COUNT (bb->succs) >= 3)
3898 error ("Wrong outgoing edge flags at end of bb %d\n",
3903 if (!has_label_p (true_edge->dest,
3904 GOTO_DESTINATION (COND_EXPR_THEN (stmt))))
3906 error ("%<then%> label does not match edge at end of bb %d\n",
3911 if (!has_label_p (false_edge->dest,
3912 GOTO_DESTINATION (COND_EXPR_ELSE (stmt))))
3914 error ("%<else%> label does not match edge at end of bb %d\n",
3922 if (simple_goto_p (stmt))
3924 error ("Explicit goto at end of bb %d\n", bb->index);
3929 /* FIXME. We should double check that the labels in the
3930 destination blocks have their address taken. */
3931 FOR_EACH_EDGE (e, ei, bb->succs)
3932 if ((e->flags & (EDGE_FALLTHRU | EDGE_TRUE_VALUE
3933 | EDGE_FALSE_VALUE))
3934 || !(e->flags & EDGE_ABNORMAL))
3936 error ("Wrong outgoing edge flags at end of bb %d\n",
3944 if (!single_succ_p (bb)
3945 || (single_succ_edge (bb)->flags
3946 & (EDGE_FALLTHRU | EDGE_ABNORMAL
3947 | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
3949 error ("Wrong outgoing edge flags at end of bb %d\n", bb->index);
3952 if (single_succ (bb) != EXIT_BLOCK_PTR)
3954 error ("Return edge does not point to exit in bb %d\n",
3967 vec = SWITCH_LABELS (stmt);
3968 n = TREE_VEC_LENGTH (vec);
3970 /* Mark all the destination basic blocks. */
3971 for (i = 0; i < n; ++i)
3973 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
3974 basic_block label_bb = label_to_block (lab);
3976 gcc_assert (!label_bb->aux || label_bb->aux == (void *)1);
3977 label_bb->aux = (void *)1;
3980 /* Verify that the case labels are sorted. */
3981 prev = TREE_VEC_ELT (vec, 0);
3982 for (i = 1; i < n - 1; ++i)
3984 tree c = TREE_VEC_ELT (vec, i);
3987 error ("Found default case not at end of case vector");
3991 if (! tree_int_cst_lt (CASE_LOW (prev), CASE_LOW (c)))
3993 error ("Case labels not sorted:\n ");
3994 print_generic_expr (stderr, prev, 0);
3995 fprintf (stderr," is greater than ");
3996 print_generic_expr (stderr, c, 0);
3997 fprintf (stderr," but comes before it.\n");
4002 if (CASE_LOW (TREE_VEC_ELT (vec, n - 1)))
4004 error ("No default case found at end of case vector");
4008 FOR_EACH_EDGE (e, ei, bb->succs)
4012 error ("Extra outgoing edge %d->%d\n",
4013 bb->index, e->dest->index);
4016 e->dest->aux = (void *)2;
4017 if ((e->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL
4018 | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
4020 error ("Wrong outgoing edge flags at end of bb %d\n",
4026 /* Check that we have all of them. */
4027 for (i = 0; i < n; ++i)
4029 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
4030 basic_block label_bb = label_to_block (lab);
4032 if (label_bb->aux != (void *)2)
4034 error ("Missing edge %i->%i",
4035 bb->index, label_bb->index);
4040 FOR_EACH_EDGE (e, ei, bb->succs)
4041 e->dest->aux = (void *)0;
4048 if (dom_computed[CDI_DOMINATORS] >= DOM_NO_FAST_QUERY)
4049 verify_dominators (CDI_DOMINATORS);
4055 /* Updates phi nodes after creating a forwarder block joined
4056 by edge FALLTHRU. */
4059 tree_make_forwarder_block (edge fallthru)
4063 basic_block dummy, bb;
4064 tree phi, new_phi, var;
4066 dummy = fallthru->src;
4067 bb = fallthru->dest;
4069 if (single_pred_p (bb))
4072 /* If we redirected a branch we must create new phi nodes at the
4074 for (phi = phi_nodes (dummy); phi; phi = PHI_CHAIN (phi))
4076 var = PHI_RESULT (phi);
4077 new_phi = create_phi_node (var, bb);
4078 SSA_NAME_DEF_STMT (var) = new_phi;
4079 SET_PHI_RESULT (phi, make_ssa_name (SSA_NAME_VAR (var), phi));
4080 add_phi_arg (new_phi, PHI_RESULT (phi), fallthru);
4083 /* Ensure that the PHI node chain is in the same order. */
4084 set_phi_nodes (bb, phi_reverse (phi_nodes (bb)));
4086 /* Add the arguments we have stored on edges. */
4087 FOR_EACH_EDGE (e, ei, bb->preds)
4092 flush_pending_stmts (e);
4097 /* Return true if basic block BB does nothing except pass control
4098 flow to another block and that we can safely insert a label at
4099 the start of the successor block.
4101 As a precondition, we require that BB be not equal to
4105 tree_forwarder_block_p (basic_block bb, bool phi_wanted)
4107 block_stmt_iterator bsi;
4109 /* BB must have a single outgoing edge. */
4110 if (single_succ_p (bb) != 1
4111 /* If PHI_WANTED is false, BB must not have any PHI nodes.
4112 Otherwise, BB must have PHI nodes. */
4113 || (phi_nodes (bb) != NULL_TREE) != phi_wanted
4114 /* BB may not be a predecessor of EXIT_BLOCK_PTR. */
4115 || single_succ (bb) == EXIT_BLOCK_PTR
4116 /* Nor should this be an infinite loop. */
4117 || single_succ (bb) == bb
4118 /* BB may not have an abnormal outgoing edge. */
4119 || (single_succ_edge (bb)->flags & EDGE_ABNORMAL))
4123 gcc_assert (bb != ENTRY_BLOCK_PTR);
4126 /* Now walk through the statements backward. We can ignore labels,
4127 anything else means this is not a forwarder block. */
4128 for (bsi = bsi_last (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4130 tree stmt = bsi_stmt (bsi);
4132 switch (TREE_CODE (stmt))
4135 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)))
4144 if (find_edge (ENTRY_BLOCK_PTR, bb))
4150 /* Protect loop latches, headers and preheaders. */
4151 if (bb->loop_father->header == bb)
4153 dest = EDGE_SUCC (bb, 0)->dest;
4155 if (dest->loop_father->header == dest)
4162 /* Return true if BB has at least one abnormal incoming edge. */
4165 has_abnormal_incoming_edge_p (basic_block bb)
4170 FOR_EACH_EDGE (e, ei, bb->preds)
4171 if (e->flags & EDGE_ABNORMAL)
4177 /* Removes forwarder block BB. Returns false if this failed. If a new
4178 forwarder block is created due to redirection of edges, it is
4179 stored to worklist. */
4182 remove_forwarder_block (basic_block bb, basic_block **worklist)
4184 edge succ = single_succ_edge (bb), e, s;
4185 basic_block dest = succ->dest;
4189 block_stmt_iterator bsi, bsi_to;
4190 bool seen_abnormal_edge = false;
4192 /* We check for infinite loops already in tree_forwarder_block_p.
4193 However it may happen that the infinite loop is created
4194 afterwards due to removal of forwarders. */
4198 /* If the destination block consists of a nonlocal label, do not merge
4200 label = first_stmt (dest);
4202 && TREE_CODE (label) == LABEL_EXPR
4203 && DECL_NONLOCAL (LABEL_EXPR_LABEL (label)))
4206 /* If there is an abnormal edge to basic block BB, but not into
4207 dest, problems might occur during removal of the phi node at out
4208 of ssa due to overlapping live ranges of registers.
4210 If there is an abnormal edge in DEST, the problems would occur
4211 anyway since cleanup_dead_labels would then merge the labels for
4212 two different eh regions, and rest of exception handling code
4215 So if there is an abnormal edge to BB, proceed only if there is
4216 no abnormal edge to DEST and there are no phi nodes in DEST. */
4217 if (has_abnormal_incoming_edge_p (bb))
4219 seen_abnormal_edge = true;
4221 if (has_abnormal_incoming_edge_p (dest)
4222 || phi_nodes (dest) != NULL_TREE)
4226 /* If there are phi nodes in DEST, and some of the blocks that are
4227 predecessors of BB are also predecessors of DEST, check that the
4228 phi node arguments match. */
4229 if (phi_nodes (dest))
4231 FOR_EACH_EDGE (e, ei, bb->preds)
4233 s = find_edge (e->src, dest);
4237 if (!phi_alternatives_equal (dest, succ, s))
4242 /* Redirect the edges. */
4243 for (ei = ei_start (bb->preds); (e = ei_safe_edge (ei)); )
4245 if (e->flags & EDGE_ABNORMAL)
4247 /* If there is an abnormal edge, redirect it anyway, and
4248 move the labels to the new block to make it legal. */
4249 s = redirect_edge_succ_nodup (e, dest);
4252 s = redirect_edge_and_branch (e, dest);
4256 /* Create arguments for the phi nodes, since the edge was not
4258 for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi))
4259 add_phi_arg (phi, PHI_ARG_DEF (phi, succ->dest_idx), s);
4263 /* The source basic block might become a forwarder. We know
4264 that it was not a forwarder before, since it used to have
4265 at least two outgoing edges, so we may just add it to
4267 if (tree_forwarder_block_p (s->src, false))
4268 *(*worklist)++ = s->src;
4272 if (seen_abnormal_edge)
4274 /* Move the labels to the new block, so that the redirection of
4275 the abnormal edges works. */
4277 bsi_to = bsi_start (dest);
4278 for (bsi = bsi_start (bb); !bsi_end_p (bsi); )
4280 label = bsi_stmt (bsi);
4281 gcc_assert (TREE_CODE (label) == LABEL_EXPR);
4283 bsi_insert_before (&bsi_to, label, BSI_CONTINUE_LINKING);
4287 /* Update the dominators. */
4288 if (dom_info_available_p (CDI_DOMINATORS))
4290 basic_block dom, dombb, domdest;
4292 dombb = get_immediate_dominator (CDI_DOMINATORS, bb);
4293 domdest = get_immediate_dominator (CDI_DOMINATORS, dest);
4296 /* Shortcut to avoid calling (relatively expensive)
4297 nearest_common_dominator unless necessary. */
4301 dom = nearest_common_dominator (CDI_DOMINATORS, domdest, dombb);
4303 set_immediate_dominator (CDI_DOMINATORS, dest, dom);
4306 /* And kill the forwarder block. */
4307 delete_basic_block (bb);
4312 /* Removes forwarder blocks. */
4315 cleanup_forwarder_blocks (void)
4318 bool changed = false;
4319 basic_block *worklist = xmalloc (sizeof (basic_block) * n_basic_blocks);
4320 basic_block *current = worklist;
4324 if (tree_forwarder_block_p (bb, false))
4328 while (current != worklist)
4331 changed |= remove_forwarder_block (bb, ¤t);
4338 /* Merge the PHI nodes at BB into those at BB's sole successor. */
4341 remove_forwarder_block_with_phi (basic_block bb)
4343 edge succ = single_succ_edge (bb);
4344 basic_block dest = succ->dest;
4346 basic_block dombb, domdest, dom;
4348 /* We check for infinite loops already in tree_forwarder_block_p.
4349 However it may happen that the infinite loop is created
4350 afterwards due to removal of forwarders. */
4354 /* If the destination block consists of a nonlocal label, do not
4356 label = first_stmt (dest);
4358 && TREE_CODE (label) == LABEL_EXPR
4359 && DECL_NONLOCAL (LABEL_EXPR_LABEL (label)))
4362 /* Redirect each incoming edge to BB to DEST. */
4363 while (EDGE_COUNT (bb->preds) > 0)
4365 edge e = EDGE_PRED (bb, 0), s;
4368 s = find_edge (e->src, dest);
4371 /* We already have an edge S from E->src to DEST. If S and
4372 E->dest's sole successor edge have the same PHI arguments
4373 at DEST, redirect S to DEST. */
4374 if (phi_alternatives_equal (dest, s, succ))
4376 e = redirect_edge_and_branch (e, dest);
4377 PENDING_STMT (e) = NULL_TREE;
4381 /* PHI arguments are different. Create a forwarder block by
4382 splitting E so that we can merge PHI arguments on E to
4384 e = single_succ_edge (split_edge (e));
4387 s = redirect_edge_and_branch (e, dest);
4389 /* redirect_edge_and_branch must not create a new edge. */
4390 gcc_assert (s == e);
4392 /* Add to the PHI nodes at DEST each PHI argument removed at the
4393 destination of E. */
4394 for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi))
4396 tree def = PHI_ARG_DEF (phi, succ->dest_idx);
4398 if (TREE_CODE (def) == SSA_NAME)
4402 /* If DEF is one of the results of PHI nodes removed during
4403 redirection, replace it with the PHI argument that used
4405 for (var = PENDING_STMT (e); var; var = TREE_CHAIN (var))
4407 tree old_arg = TREE_PURPOSE (var);
4408 tree new_arg = TREE_VALUE (var);
4418 add_phi_arg (phi, def, s);
4421 PENDING_STMT (e) = NULL;
4424 /* Update the dominators. */
4425 dombb = get_immediate_dominator (CDI_DOMINATORS, bb);
4426 domdest = get_immediate_dominator (CDI_DOMINATORS, dest);
4429 /* Shortcut to avoid calling (relatively expensive)
4430 nearest_common_dominator unless necessary. */
4434 dom = nearest_common_dominator (CDI_DOMINATORS, domdest, dombb);
4436 set_immediate_dominator (CDI_DOMINATORS, dest, dom);
4438 /* Remove BB since all of BB's incoming edges have been redirected
4440 delete_basic_block (bb);
4443 /* This pass merges PHI nodes if one feeds into another. For example,
4444 suppose we have the following:
4451 # tem_6 = PHI <tem_17(8), tem_23(7)>;
4454 # tem_3 = PHI <tem_6(9), tem_2(5)>;
4457 Then we merge the first PHI node into the second one like so:
4459 goto <bb 9> (<L10>);
4464 # tem_3 = PHI <tem_23(7), tem_2(5), tem_17(8)>;
4469 merge_phi_nodes (void)
4471 basic_block *worklist = xmalloc (sizeof (basic_block) * n_basic_blocks);
4472 basic_block *current = worklist;
4475 calculate_dominance_info (CDI_DOMINATORS);
4477 /* Find all PHI nodes that we may be able to merge. */
4482 /* Look for a forwarder block with PHI nodes. */
4483 if (!tree_forwarder_block_p (bb, true))
4486 dest = single_succ (bb);
4488 /* We have to feed into another basic block with PHI
4490 if (!phi_nodes (dest)
4491 /* We don't want to deal with a basic block with
4493 || has_abnormal_incoming_edge_p (bb))
4496 if (!dominated_by_p (CDI_DOMINATORS, dest, bb))
4498 /* If BB does not dominate DEST, then the PHI nodes at
4499 DEST must be the only users of the results of the PHI
4505 /* Now let's drain WORKLIST. */
4506 while (current != worklist)
4509 remove_forwarder_block_with_phi (bb);
4516 gate_merge_phi (void)
4521 struct tree_opt_pass pass_merge_phi = {
4522 "mergephi", /* name */
4523 gate_merge_phi, /* gate */
4524 merge_phi_nodes, /* execute */
4527 0, /* static_pass_number */
4528 TV_TREE_MERGE_PHI, /* tv_id */
4529 PROP_cfg | PROP_ssa, /* properties_required */
4530 0, /* properties_provided */
4531 0, /* properties_destroyed */
4532 0, /* todo_flags_start */
4533 TODO_dump_func | TODO_ggc_collect /* todo_flags_finish */
4538 /* Return a non-special label in the head of basic block BLOCK.
4539 Create one if it doesn't exist. */
4542 tree_block_label (basic_block bb)
4544 block_stmt_iterator i, s = bsi_start (bb);
4548 for (i = s; !bsi_end_p (i); first = false, bsi_next (&i))
4550 stmt = bsi_stmt (i);
4551 if (TREE_CODE (stmt) != LABEL_EXPR)
4553 label = LABEL_EXPR_LABEL (stmt);
4554 if (!DECL_NONLOCAL (label))
4557 bsi_move_before (&i, &s);
4562 label = create_artificial_label ();
4563 stmt = build1 (LABEL_EXPR, void_type_node, label);
4564 bsi_insert_before (&s, stmt, BSI_NEW_STMT);
4569 /* Attempt to perform edge redirection by replacing a possibly complex
4570 jump instruction by a goto or by removing the jump completely.
4571 This can apply only if all edges now point to the same block. The
4572 parameters and return values are equivalent to
4573 redirect_edge_and_branch. */
4576 tree_try_redirect_by_replacing_jump (edge e, basic_block target)
4578 basic_block src = e->src;
4579 block_stmt_iterator b;
4582 /* We can replace or remove a complex jump only when we have exactly
4584 if (EDGE_COUNT (src->succs) != 2
4585 /* Verify that all targets will be TARGET. Specifically, the
4586 edge that is not E must also go to TARGET. */
4587 || EDGE_SUCC (src, EDGE_SUCC (src, 0) == e)->dest != target)
4593 stmt = bsi_stmt (b);
4595 if (TREE_CODE (stmt) == COND_EXPR
4596 || TREE_CODE (stmt) == SWITCH_EXPR)
4599 e = ssa_redirect_edge (e, target);
4600 e->flags = EDGE_FALLTHRU;
4608 /* Redirect E to DEST. Return NULL on failure. Otherwise, return the
4609 edge representing the redirected branch. */
4612 tree_redirect_edge_and_branch (edge e, basic_block dest)
4614 basic_block bb = e->src;
4615 block_stmt_iterator bsi;
4619 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
4622 if (e->src != ENTRY_BLOCK_PTR
4623 && (ret = tree_try_redirect_by_replacing_jump (e, dest)))
4626 if (e->dest == dest)
4629 label = tree_block_label (dest);
4631 bsi = bsi_last (bb);
4632 stmt = bsi_end_p (bsi) ? NULL : bsi_stmt (bsi);
4634 switch (stmt ? TREE_CODE (stmt) : ERROR_MARK)
4637 stmt = (e->flags & EDGE_TRUE_VALUE
4638 ? COND_EXPR_THEN (stmt)
4639 : COND_EXPR_ELSE (stmt));
4640 GOTO_DESTINATION (stmt) = label;
4644 /* No non-abnormal edges should lead from a non-simple goto, and
4645 simple ones should be represented implicitly. */
4650 tree cases = get_cases_for_edge (e, stmt);
4652 /* If we have a list of cases associated with E, then use it
4653 as it's a lot faster than walking the entire case vector. */
4656 edge e2 = find_edge (e->src, dest);
4663 CASE_LABEL (cases) = label;
4664 cases = TREE_CHAIN (cases);
4667 /* If there was already an edge in the CFG, then we need
4668 to move all the cases associated with E to E2. */
4671 tree cases2 = get_cases_for_edge (e2, stmt);
4673 TREE_CHAIN (last) = TREE_CHAIN (cases2);
4674 TREE_CHAIN (cases2) = first;
4679 tree vec = SWITCH_LABELS (stmt);
4680 size_t i, n = TREE_VEC_LENGTH (vec);
4682 for (i = 0; i < n; i++)
4684 tree elt = TREE_VEC_ELT (vec, i);
4686 if (label_to_block (CASE_LABEL (elt)) == e->dest)
4687 CASE_LABEL (elt) = label;
4696 e->flags |= EDGE_FALLTHRU;
4700 /* Otherwise it must be a fallthru edge, and we don't need to
4701 do anything besides redirecting it. */
4702 gcc_assert (e->flags & EDGE_FALLTHRU);
4706 /* Update/insert PHI nodes as necessary. */
4708 /* Now update the edges in the CFG. */
4709 e = ssa_redirect_edge (e, dest);
4715 /* Simple wrapper, as we can always redirect fallthru edges. */
4718 tree_redirect_edge_and_branch_force (edge e, basic_block dest)
4720 e = tree_redirect_edge_and_branch (e, dest);
4727 /* Splits basic block BB after statement STMT (but at least after the
4728 labels). If STMT is NULL, BB is split just after the labels. */
4731 tree_split_block (basic_block bb, void *stmt)
4733 block_stmt_iterator bsi, bsi_tgt;
4739 new_bb = create_empty_bb (bb);
4741 /* Redirect the outgoing edges. */
4742 new_bb->succs = bb->succs;
4744 FOR_EACH_EDGE (e, ei, new_bb->succs)
4747 if (stmt && TREE_CODE ((tree) stmt) == LABEL_EXPR)
4750 /* Move everything from BSI to the new basic block. */
4751 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4753 act = bsi_stmt (bsi);
4754 if (TREE_CODE (act) == LABEL_EXPR)
4767 bsi_tgt = bsi_start (new_bb);
4768 while (!bsi_end_p (bsi))
4770 act = bsi_stmt (bsi);
4772 bsi_insert_after (&bsi_tgt, act, BSI_NEW_STMT);
4779 /* Moves basic block BB after block AFTER. */
4782 tree_move_block_after (basic_block bb, basic_block after)
4784 if (bb->prev_bb == after)
4788 link_block (bb, after);
4794 /* Return true if basic_block can be duplicated. */
4797 tree_can_duplicate_bb_p (basic_block bb ATTRIBUTE_UNUSED)
4802 /* Create a duplicate of the basic block BB. NOTE: This does not
4803 preserve SSA form. */
4806 tree_duplicate_bb (basic_block bb)
4809 block_stmt_iterator bsi, bsi_tgt;
4811 ssa_op_iter op_iter;
4813 new_bb = create_empty_bb (EXIT_BLOCK_PTR->prev_bb);
4815 /* First copy the phi nodes. We do not copy phi node arguments here,
4816 since the edges are not ready yet. Keep the chain of phi nodes in
4817 the same order, so that we can add them later. */
4818 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
4820 mark_for_rewrite (PHI_RESULT (phi));
4821 create_phi_node (PHI_RESULT (phi), new_bb);
4823 set_phi_nodes (new_bb, phi_reverse (phi_nodes (new_bb)));
4825 bsi_tgt = bsi_start (new_bb);
4826 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4828 tree stmt = bsi_stmt (bsi);
4831 if (TREE_CODE (stmt) == LABEL_EXPR)
4834 /* Record the definitions. */
4835 get_stmt_operands (stmt);
4837 FOR_EACH_SSA_TREE_OPERAND (val, stmt, op_iter, SSA_OP_ALL_DEFS)
4838 mark_for_rewrite (val);
4840 copy = unshare_expr (stmt);
4842 /* Copy also the virtual operands. */
4843 get_stmt_ann (copy);
4844 copy_virtual_operands (copy, stmt);
4846 bsi_insert_after (&bsi_tgt, copy, BSI_NEW_STMT);
4852 /* Basic block BB_COPY was created by code duplication. Add phi node
4853 arguments for edges going out of BB_COPY. The blocks that were
4854 duplicated have rbi->duplicated set to one. */
4857 add_phi_args_after_copy_bb (basic_block bb_copy)
4859 basic_block bb, dest;
4862 tree phi, phi_copy, phi_next, def;
4864 bb = bb_copy->rbi->original;
4866 FOR_EACH_EDGE (e_copy, ei, bb_copy->succs)
4868 if (!phi_nodes (e_copy->dest))
4871 if (e_copy->dest->rbi->duplicated)
4872 dest = e_copy->dest->rbi->original;
4874 dest = e_copy->dest;
4876 e = find_edge (bb, dest);
4879 /* During loop unrolling the target of the latch edge is copied.
4880 In this case we are not looking for edge to dest, but to
4881 duplicated block whose original was dest. */
4882 FOR_EACH_EDGE (e, ei, bb->succs)
4883 if (e->dest->rbi->duplicated
4884 && e->dest->rbi->original == dest)
4887 gcc_assert (e != NULL);
4890 for (phi = phi_nodes (e->dest), phi_copy = phi_nodes (e_copy->dest);
4892 phi = phi_next, phi_copy = PHI_CHAIN (phi_copy))
4894 phi_next = PHI_CHAIN (phi);
4896 gcc_assert (PHI_RESULT (phi) == PHI_RESULT (phi_copy));
4897 def = PHI_ARG_DEF_FROM_EDGE (phi, e);
4898 add_phi_arg (phi_copy, def, e_copy);
4903 /* Blocks in REGION_COPY array of length N_REGION were created by
4904 duplication of basic blocks. Add phi node arguments for edges
4905 going from these blocks. */
4908 add_phi_args_after_copy (basic_block *region_copy, unsigned n_region)
4912 for (i = 0; i < n_region; i++)
4913 region_copy[i]->rbi->duplicated = 1;
4915 for (i = 0; i < n_region; i++)
4916 add_phi_args_after_copy_bb (region_copy[i]);
4918 for (i = 0; i < n_region; i++)
4919 region_copy[i]->rbi->duplicated = 0;
4922 /* Maps the old ssa name FROM_NAME to TO_NAME. */
4924 struct ssa_name_map_entry
4930 /* Hash function for ssa_name_map_entry. */
4933 ssa_name_map_entry_hash (const void *entry)
4935 const struct ssa_name_map_entry *en = entry;
4936 return SSA_NAME_VERSION (en->from_name);
4939 /* Equality function for ssa_name_map_entry. */
4942 ssa_name_map_entry_eq (const void *in_table, const void *ssa_name)
4944 const struct ssa_name_map_entry *en = in_table;
4946 return en->from_name == ssa_name;
4949 /* Allocate duplicates of ssa names in list DEFINITIONS and store the mapping
4953 allocate_ssa_names (bitmap definitions, htab_t *map)
4956 struct ssa_name_map_entry *entry;
4962 *map = htab_create (10, ssa_name_map_entry_hash,
4963 ssa_name_map_entry_eq, free);
4964 EXECUTE_IF_SET_IN_BITMAP (definitions, 0, ver, bi)
4966 name = ssa_name (ver);
4967 slot = htab_find_slot_with_hash (*map, name, SSA_NAME_VERSION (name),
4973 entry = xmalloc (sizeof (struct ssa_name_map_entry));
4974 entry->from_name = name;
4977 entry->to_name = duplicate_ssa_name (name, SSA_NAME_DEF_STMT (name));
4981 /* Rewrite the definition DEF in statement STMT to new ssa name as specified
4982 by the mapping MAP. */
4985 rewrite_to_new_ssa_names_def (def_operand_p def, tree stmt, htab_t map)
4987 tree name = DEF_FROM_PTR (def);
4988 struct ssa_name_map_entry *entry;
4990 gcc_assert (TREE_CODE (name) == SSA_NAME);
4992 entry = htab_find_with_hash (map, name, SSA_NAME_VERSION (name));
4996 SET_DEF (def, entry->to_name);
4997 SSA_NAME_DEF_STMT (entry->to_name) = stmt;
5000 /* Rewrite the USE to new ssa name as specified by the mapping MAP. */
5003 rewrite_to_new_ssa_names_use (use_operand_p use, htab_t map)
5005 tree name = USE_FROM_PTR (use);
5006 struct ssa_name_map_entry *entry;
5008 if (TREE_CODE (name) != SSA_NAME)
5011 entry = htab_find_with_hash (map, name, SSA_NAME_VERSION (name));
5015 SET_USE (use, entry->to_name);
5018 /* Rewrite the ssa names in basic block BB to new ones as specified by the
5022 rewrite_to_new_ssa_names_bb (basic_block bb, htab_t map)
5028 block_stmt_iterator bsi;
5032 v_may_def_optype v_may_defs;
5033 v_must_def_optype v_must_defs;
5036 FOR_EACH_EDGE (e, ei, bb->preds)
5037 if (e->flags & EDGE_ABNORMAL)
5040 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
5042 rewrite_to_new_ssa_names_def (PHI_RESULT_PTR (phi), phi, map);
5044 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (PHI_RESULT (phi)) = 1;
5047 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
5049 stmt = bsi_stmt (bsi);
5050 get_stmt_operands (stmt);
5051 ann = stmt_ann (stmt);
5053 uses = USE_OPS (ann);
5054 for (i = 0; i < NUM_USES (uses); i++)
5055 rewrite_to_new_ssa_names_use (USE_OP_PTR (uses, i), map);
5057 defs = DEF_OPS (ann);
5058 for (i = 0; i < NUM_DEFS (defs); i++)
5059 rewrite_to_new_ssa_names_def (DEF_OP_PTR (defs, i), stmt, map);
5061 vuses = VUSE_OPS (ann);
5062 for (i = 0; i < NUM_VUSES (vuses); i++)
5063 rewrite_to_new_ssa_names_use (VUSE_OP_PTR (vuses, i), map);
5065 v_may_defs = V_MAY_DEF_OPS (ann);
5066 for (i = 0; i < NUM_V_MAY_DEFS (v_may_defs); i++)
5068 rewrite_to_new_ssa_names_use
5069 (V_MAY_DEF_OP_PTR (v_may_defs, i), map);
5070 rewrite_to_new_ssa_names_def
5071 (V_MAY_DEF_RESULT_PTR (v_may_defs, i), stmt, map);
5074 v_must_defs = V_MUST_DEF_OPS (ann);
5075 for (i = 0; i < NUM_V_MUST_DEFS (v_must_defs); i++)
5077 rewrite_to_new_ssa_names_def
5078 (V_MUST_DEF_RESULT_PTR (v_must_defs, i), stmt, map);
5079 rewrite_to_new_ssa_names_use
5080 (V_MUST_DEF_KILL_PTR (v_must_defs, i), map);
5084 FOR_EACH_EDGE (e, ei, bb->succs)
5085 for (phi = phi_nodes (e->dest); phi; phi = PHI_CHAIN (phi))
5087 rewrite_to_new_ssa_names_use
5088 (PHI_ARG_DEF_PTR_FROM_EDGE (phi, e), map);
5090 if (e->flags & EDGE_ABNORMAL)
5092 tree op = PHI_ARG_DEF_FROM_EDGE (phi, e);
5093 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op) = 1;
5098 /* Rewrite the ssa names in N_REGION blocks REGION to the new ones as specified
5099 by the mapping MAP. */
5102 rewrite_to_new_ssa_names (basic_block *region, unsigned n_region, htab_t map)
5106 for (r = 0; r < n_region; r++)
5107 rewrite_to_new_ssa_names_bb (region[r], map);
5110 /* Duplicates a REGION (set of N_REGION basic blocks) with just a single
5111 important exit edge EXIT. By important we mean that no SSA name defined
5112 inside region is live over the other exit edges of the region. All entry
5113 edges to the region must go to ENTRY->dest. The edge ENTRY is redirected
5114 to the duplicate of the region. SSA form, dominance and loop information
5115 is updated. The new basic blocks are stored to REGION_COPY in the same
5116 order as they had in REGION, provided that REGION_COPY is not NULL.
5117 The function returns false if it is unable to copy the region,
5121 tree_duplicate_sese_region (edge entry, edge exit,
5122 basic_block *region, unsigned n_region,
5123 basic_block *region_copy)
5125 unsigned i, n_doms, ver;
5126 bool free_region_copy = false, copying_header = false;
5127 struct loop *loop = entry->dest->loop_father;
5132 htab_t ssa_name_map = NULL;
5136 if (!can_copy_bbs_p (region, n_region))
5139 /* Some sanity checking. Note that we do not check for all possible
5140 missuses of the functions. I.e. if you ask to copy something weird,
5141 it will work, but the state of structures probably will not be
5144 for (i = 0; i < n_region; i++)
5146 /* We do not handle subloops, i.e. all the blocks must belong to the
5148 if (region[i]->loop_father != loop)
5151 if (region[i] != entry->dest
5152 && region[i] == loop->header)
5158 /* In case the function is used for loop header copying (which is the primary
5159 use), ensure that EXIT and its copy will be new latch and entry edges. */
5160 if (loop->header == entry->dest)
5162 copying_header = true;
5163 loop->copy = loop->outer;
5165 if (!dominated_by_p (CDI_DOMINATORS, loop->latch, exit->src))
5168 for (i = 0; i < n_region; i++)
5169 if (region[i] != exit->src
5170 && dominated_by_p (CDI_DOMINATORS, region[i], exit->src))
5176 region_copy = xmalloc (sizeof (basic_block) * n_region);
5177 free_region_copy = true;
5180 gcc_assert (!any_marked_for_rewrite_p ());
5182 /* Record blocks outside the region that are duplicated by something
5184 doms = xmalloc (sizeof (basic_block) * n_basic_blocks);
5185 n_doms = get_dominated_by_region (CDI_DOMINATORS, region, n_region, doms);
5187 copy_bbs (region, n_region, region_copy, &exit, 1, &exit_copy, loop);
5188 definitions = marked_ssa_names ();
5192 loop->header = exit->dest;
5193 loop->latch = exit->src;
5196 /* Redirect the entry and add the phi node arguments. */
5197 redirected = redirect_edge_and_branch (entry, entry->dest->rbi->copy);
5198 gcc_assert (redirected != NULL);
5199 flush_pending_stmts (entry);
5201 /* Concerning updating of dominators: We must recount dominators
5202 for entry block and its copy. Anything that is outside of the region, but
5203 was dominated by something inside needs recounting as well. */
5204 set_immediate_dominator (CDI_DOMINATORS, entry->dest, entry->src);
5205 doms[n_doms++] = entry->dest->rbi->original;
5206 iterate_fix_dominators (CDI_DOMINATORS, doms, n_doms);
5209 /* Add the other phi node arguments. */
5210 add_phi_args_after_copy (region_copy, n_region);
5212 /* Add phi nodes for definitions at exit. TODO -- once we have immediate
5213 uses, it should be possible to emit phi nodes just for definitions that
5214 are used outside region. */
5215 EXECUTE_IF_SET_IN_BITMAP (definitions, 0, ver, bi)
5217 tree name = ssa_name (ver);
5219 phi = create_phi_node (name, exit->dest);
5220 add_phi_arg (phi, name, exit);
5221 add_phi_arg (phi, name, exit_copy);
5223 SSA_NAME_DEF_STMT (name) = phi;
5226 /* And create new definitions inside region and its copy. TODO -- once we
5227 have immediate uses, it might be better to leave definitions in region
5228 unchanged, create new ssa names for phi nodes on exit, and rewrite
5229 the uses, to avoid changing the copied region. */
5230 allocate_ssa_names (definitions, &ssa_name_map);
5231 rewrite_to_new_ssa_names (region, n_region, ssa_name_map);
5232 allocate_ssa_names (definitions, &ssa_name_map);
5233 rewrite_to_new_ssa_names (region_copy, n_region, ssa_name_map);
5234 htab_delete (ssa_name_map);
5236 if (free_region_copy)
5239 unmark_all_for_rewrite ();
5240 BITMAP_FREE (definitions);
5245 /* Dump FUNCTION_DECL FN to file FILE using FLAGS (see TDF_* in tree.h) */
5248 dump_function_to_file (tree fn, FILE *file, int flags)
5250 tree arg, vars, var;
5251 bool ignore_topmost_bind = false, any_var = false;
5255 fprintf (file, "%s (", lang_hooks.decl_printable_name (fn, 2));
5257 arg = DECL_ARGUMENTS (fn);
5260 print_generic_expr (file, arg, dump_flags);
5261 if (TREE_CHAIN (arg))
5262 fprintf (file, ", ");
5263 arg = TREE_CHAIN (arg);
5265 fprintf (file, ")\n");
5267 if (flags & TDF_RAW)
5269 dump_node (fn, TDF_SLIM | flags, file);
5273 /* When GIMPLE is lowered, the variables are no longer available in
5274 BIND_EXPRs, so display them separately. */
5275 if (cfun && cfun->unexpanded_var_list)
5277 ignore_topmost_bind = true;
5279 fprintf (file, "{\n");
5280 for (vars = cfun->unexpanded_var_list; vars; vars = TREE_CHAIN (vars))
5282 var = TREE_VALUE (vars);
5284 print_generic_decl (file, var, flags);
5285 fprintf (file, "\n");
5291 if (basic_block_info)
5293 /* Make a CFG based dump. */
5294 check_bb_profile (ENTRY_BLOCK_PTR, file);
5295 if (!ignore_topmost_bind)
5296 fprintf (file, "{\n");
5298 if (any_var && n_basic_blocks)
5299 fprintf (file, "\n");
5302 dump_generic_bb (file, bb, 2, flags);
5304 fprintf (file, "}\n");
5305 check_bb_profile (EXIT_BLOCK_PTR, file);
5311 /* Make a tree based dump. */
5312 chain = DECL_SAVED_TREE (fn);
5314 if (TREE_CODE (chain) == BIND_EXPR)
5316 if (ignore_topmost_bind)
5318 chain = BIND_EXPR_BODY (chain);
5326 if (!ignore_topmost_bind)
5327 fprintf (file, "{\n");
5332 fprintf (file, "\n");
5334 print_generic_stmt_indented (file, chain, flags, indent);
5335 if (ignore_topmost_bind)
5336 fprintf (file, "}\n");
5339 fprintf (file, "\n\n");
5343 /* Pretty print of the loops intermediate representation. */
5344 static void print_loop (FILE *, struct loop *, int);
5345 static void print_pred_bbs (FILE *, basic_block bb);
5346 static void print_succ_bbs (FILE *, basic_block bb);
5349 /* Print the predecessors indexes of edge E on FILE. */
5352 print_pred_bbs (FILE *file, basic_block bb)
5357 FOR_EACH_EDGE (e, ei, bb->preds)
5358 fprintf (file, "bb_%d", e->src->index);
5362 /* Print the successors indexes of edge E on FILE. */
5365 print_succ_bbs (FILE *file, basic_block bb)
5370 FOR_EACH_EDGE (e, ei, bb->succs)
5371 fprintf (file, "bb_%d", e->src->index);
5375 /* Pretty print LOOP on FILE, indented INDENT spaces. */
5378 print_loop (FILE *file, struct loop *loop, int indent)
5386 s_indent = (char *) alloca ((size_t) indent + 1);
5387 memset ((void *) s_indent, ' ', (size_t) indent);
5388 s_indent[indent] = '\0';
5390 /* Print the loop's header. */
5391 fprintf (file, "%sloop_%d\n", s_indent, loop->num);
5393 /* Print the loop's body. */
5394 fprintf (file, "%s{\n", s_indent);
5396 if (bb->loop_father == loop)
5398 /* Print the basic_block's header. */
5399 fprintf (file, "%s bb_%d (preds = {", s_indent, bb->index);
5400 print_pred_bbs (file, bb);
5401 fprintf (file, "}, succs = {");
5402 print_succ_bbs (file, bb);
5403 fprintf (file, "})\n");
5405 /* Print the basic_block's body. */
5406 fprintf (file, "%s {\n", s_indent);
5407 tree_dump_bb (bb, file, indent + 4);
5408 fprintf (file, "%s }\n", s_indent);
5411 print_loop (file, loop->inner, indent + 2);
5412 fprintf (file, "%s}\n", s_indent);
5413 print_loop (file, loop->next, indent);
5417 /* Follow a CFG edge from the entry point of the program, and on entry
5418 of a loop, pretty print the loop structure on FILE. */
5421 print_loop_ir (FILE *file)
5425 bb = BASIC_BLOCK (0);
5426 if (bb && bb->loop_father)
5427 print_loop (file, bb->loop_father, 0);
5431 /* Debugging loops structure at tree level. */
5434 debug_loop_ir (void)
5436 print_loop_ir (stderr);
5440 /* Return true if BB ends with a call, possibly followed by some
5441 instructions that must stay with the call. Return false,
5445 tree_block_ends_with_call_p (basic_block bb)
5447 block_stmt_iterator bsi = bsi_last (bb);
5448 return get_call_expr_in (bsi_stmt (bsi)) != NULL;
5452 /* Return true if BB ends with a conditional branch. Return false,
5456 tree_block_ends_with_condjump_p (basic_block bb)
5458 tree stmt = tsi_stmt (bsi_last (bb).tsi);
5459 return (TREE_CODE (stmt) == COND_EXPR);
5463 /* Return true if we need to add fake edge to exit at statement T.
5464 Helper function for tree_flow_call_edges_add. */
5467 need_fake_edge_p (tree t)
5471 /* NORETURN and LONGJMP calls already have an edge to exit.
5472 CONST and PURE calls do not need one.
5473 We don't currently check for CONST and PURE here, although
5474 it would be a good idea, because those attributes are
5475 figured out from the RTL in mark_constant_function, and
5476 the counter incrementation code from -fprofile-arcs
5477 leads to different results from -fbranch-probabilities. */
5478 call = get_call_expr_in (t);
5480 && !(call_expr_flags (call) & ECF_NORETURN))
5483 if (TREE_CODE (t) == ASM_EXPR
5484 && (ASM_VOLATILE_P (t) || ASM_INPUT_P (t)))
5491 /* Add fake edges to the function exit for any non constant and non
5492 noreturn calls, volatile inline assembly in the bitmap of blocks
5493 specified by BLOCKS or to the whole CFG if BLOCKS is zero. Return
5494 the number of blocks that were split.
5496 The goal is to expose cases in which entering a basic block does
5497 not imply that all subsequent instructions must be executed. */
5500 tree_flow_call_edges_add (sbitmap blocks)
5503 int blocks_split = 0;
5504 int last_bb = last_basic_block;
5505 bool check_last_block = false;
5507 if (n_basic_blocks == 0)
5511 check_last_block = true;
5513 check_last_block = TEST_BIT (blocks, EXIT_BLOCK_PTR->prev_bb->index);
5515 /* In the last basic block, before epilogue generation, there will be
5516 a fallthru edge to EXIT. Special care is required if the last insn
5517 of the last basic block is a call because make_edge folds duplicate
5518 edges, which would result in the fallthru edge also being marked
5519 fake, which would result in the fallthru edge being removed by
5520 remove_fake_edges, which would result in an invalid CFG.
5522 Moreover, we can't elide the outgoing fake edge, since the block
5523 profiler needs to take this into account in order to solve the minimal
5524 spanning tree in the case that the call doesn't return.
5526 Handle this by adding a dummy instruction in a new last basic block. */
5527 if (check_last_block)
5529 basic_block bb = EXIT_BLOCK_PTR->prev_bb;
5530 block_stmt_iterator bsi = bsi_last (bb);
5532 if (!bsi_end_p (bsi))
5535 if (need_fake_edge_p (t))
5539 e = find_edge (bb, EXIT_BLOCK_PTR);
5542 bsi_insert_on_edge (e, build_empty_stmt ());
5543 bsi_commit_edge_inserts ();
5548 /* Now add fake edges to the function exit for any non constant
5549 calls since there is no way that we can determine if they will
5551 for (i = 0; i < last_bb; i++)
5553 basic_block bb = BASIC_BLOCK (i);
5554 block_stmt_iterator bsi;
5555 tree stmt, last_stmt;
5560 if (blocks && !TEST_BIT (blocks, i))
5563 bsi = bsi_last (bb);
5564 if (!bsi_end_p (bsi))
5566 last_stmt = bsi_stmt (bsi);
5569 stmt = bsi_stmt (bsi);
5570 if (need_fake_edge_p (stmt))
5573 /* The handling above of the final block before the
5574 epilogue should be enough to verify that there is
5575 no edge to the exit block in CFG already.
5576 Calling make_edge in such case would cause us to
5577 mark that edge as fake and remove it later. */
5578 #ifdef ENABLE_CHECKING
5579 if (stmt == last_stmt)
5581 e = find_edge (bb, EXIT_BLOCK_PTR);
5582 gcc_assert (e == NULL);
5586 /* Note that the following may create a new basic block
5587 and renumber the existing basic blocks. */
5588 if (stmt != last_stmt)
5590 e = split_block (bb, stmt);
5594 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
5598 while (!bsi_end_p (bsi));
5603 verify_flow_info ();
5605 return blocks_split;
5609 tree_purge_dead_eh_edges (basic_block bb)
5611 bool changed = false;
5614 tree stmt = last_stmt (bb);
5616 if (stmt && tree_can_throw_internal (stmt))
5619 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
5621 if (e->flags & EDGE_EH)
5630 /* Removal of dead EH edges might change dominators of not
5631 just immediate successors. E.g. when bb1 is changed so that
5632 it no longer can throw and bb1->bb3 and bb1->bb4 are dead
5633 eh edges purged by this function in:
5645 idom(bb5) must be recomputed. For now just free the dominance
5648 free_dominance_info (CDI_DOMINATORS);
5654 tree_purge_all_dead_eh_edges (bitmap blocks)
5656 bool changed = false;
5660 EXECUTE_IF_SET_IN_BITMAP (blocks, 0, i, bi)
5662 changed |= tree_purge_dead_eh_edges (BASIC_BLOCK (i));
5668 /* This function is called whenever a new edge is created or
5672 tree_execute_on_growing_pred (edge e)
5674 basic_block bb = e->dest;
5677 reserve_phi_args_for_new_edge (bb);
5680 /* This function is called immediately before edge E is removed from
5681 the edge vector E->dest->preds. */
5684 tree_execute_on_shrinking_pred (edge e)
5686 if (phi_nodes (e->dest))
5687 remove_phi_args (e);
5690 struct cfg_hooks tree_cfg_hooks = {
5692 tree_verify_flow_info,
5693 tree_dump_bb, /* dump_bb */
5694 create_bb, /* create_basic_block */
5695 tree_redirect_edge_and_branch,/* redirect_edge_and_branch */
5696 tree_redirect_edge_and_branch_force,/* redirect_edge_and_branch_force */
5697 remove_bb, /* delete_basic_block */
5698 tree_split_block, /* split_block */
5699 tree_move_block_after, /* move_block_after */
5700 tree_can_merge_blocks_p, /* can_merge_blocks_p */
5701 tree_merge_blocks, /* merge_blocks */
5702 tree_predict_edge, /* predict_edge */
5703 tree_predicted_by_p, /* predicted_by_p */
5704 tree_can_duplicate_bb_p, /* can_duplicate_block_p */
5705 tree_duplicate_bb, /* duplicate_block */
5706 tree_split_edge, /* split_edge */
5707 tree_make_forwarder_block, /* make_forward_block */
5708 NULL, /* tidy_fallthru_edge */
5709 tree_block_ends_with_call_p, /* block_ends_with_call_p */
5710 tree_block_ends_with_condjump_p, /* block_ends_with_condjump_p */
5711 tree_flow_call_edges_add, /* flow_call_edges_add */
5712 tree_execute_on_growing_pred, /* execute_on_growing_pred */
5713 tree_execute_on_shrinking_pred, /* execute_on_shrinking_pred */
5717 /* Split all critical edges. */
5720 split_critical_edges (void)
5726 /* split_edge can redirect edges out of SWITCH_EXPRs, which can get
5727 expensive. So we want to enable recording of edge to CASE_LABEL_EXPR
5728 mappings around the calls to split_edge. */
5729 start_recording_case_labels ();
5732 FOR_EACH_EDGE (e, ei, bb->succs)
5733 if (EDGE_CRITICAL_P (e) && !(e->flags & EDGE_ABNORMAL))
5738 end_recording_case_labels ();
5741 struct tree_opt_pass pass_split_crit_edges =
5743 "crited", /* name */
5745 split_critical_edges, /* execute */
5748 0, /* static_pass_number */
5749 TV_TREE_SPLIT_EDGES, /* tv_id */
5750 PROP_cfg, /* properties required */
5751 PROP_no_crit_edges, /* properties_provided */
5752 0, /* properties_destroyed */
5753 0, /* todo_flags_start */
5754 TODO_dump_func, /* todo_flags_finish */
5759 /* Return EXP if it is a valid GIMPLE rvalue, else gimplify it into
5760 a temporary, make sure and register it to be renamed if necessary,
5761 and finally return the temporary. Put the statements to compute
5762 EXP before the current statement in BSI. */
5765 gimplify_val (block_stmt_iterator *bsi, tree type, tree exp)
5767 tree t, new_stmt, orig_stmt;
5769 if (is_gimple_val (exp))
5772 t = make_rename_temp (type, NULL);
5773 new_stmt = build (MODIFY_EXPR, type, t, exp);
5775 orig_stmt = bsi_stmt (*bsi);
5776 SET_EXPR_LOCUS (new_stmt, EXPR_LOCUS (orig_stmt));
5777 TREE_BLOCK (new_stmt) = TREE_BLOCK (orig_stmt);
5779 bsi_insert_before (bsi, new_stmt, BSI_SAME_STMT);
5784 /* Build a ternary operation and gimplify it. Emit code before BSI.
5785 Return the gimple_val holding the result. */
5788 gimplify_build3 (block_stmt_iterator *bsi, enum tree_code code,
5789 tree type, tree a, tree b, tree c)
5793 ret = fold (build3 (code, type, a, b, c));
5796 return gimplify_val (bsi, type, ret);
5799 /* Build a binary operation and gimplify it. Emit code before BSI.
5800 Return the gimple_val holding the result. */
5803 gimplify_build2 (block_stmt_iterator *bsi, enum tree_code code,
5804 tree type, tree a, tree b)
5808 ret = fold (build2 (code, type, a, b));
5811 return gimplify_val (bsi, type, ret);
5814 /* Build a unary operation and gimplify it. Emit code before BSI.
5815 Return the gimple_val holding the result. */
5818 gimplify_build1 (block_stmt_iterator *bsi, enum tree_code code, tree type,
5823 ret = fold (build1 (code, type, a));
5826 return gimplify_val (bsi, type, ret);
5831 /* Emit return warnings. */
5834 execute_warn_function_return (void)
5836 #ifdef USE_MAPPED_LOCATION
5837 source_location location;
5845 if (warn_missing_noreturn
5846 && !TREE_THIS_VOLATILE (cfun->decl)
5847 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) == 0
5848 && !lang_hooks.function.missing_noreturn_ok_p (cfun->decl))
5849 warning ("%Jfunction might be possible candidate for "
5850 "attribute %<noreturn%>",
5853 /* If we have a path to EXIT, then we do return. */
5854 if (TREE_THIS_VOLATILE (cfun->decl)
5855 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) > 0)
5857 #ifdef USE_MAPPED_LOCATION
5858 location = UNKNOWN_LOCATION;
5862 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
5864 last = last_stmt (e->src);
5865 if (TREE_CODE (last) == RETURN_EXPR
5866 #ifdef USE_MAPPED_LOCATION
5867 && (location = EXPR_LOCATION (last)) != UNKNOWN_LOCATION)
5869 && (locus = EXPR_LOCUS (last)) != NULL)
5873 #ifdef USE_MAPPED_LOCATION
5874 if (location == UNKNOWN_LOCATION)
5875 location = cfun->function_end_locus;
5876 warning ("%H%<noreturn%> function does return", &location);
5879 locus = &cfun->function_end_locus;
5880 warning ("%H%<noreturn%> function does return", locus);
5884 /* If we see "return;" in some basic block, then we do reach the end
5885 without returning a value. */
5886 else if (warn_return_type
5887 && !TREE_NO_WARNING (cfun->decl)
5888 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) > 0
5889 && !VOID_TYPE_P (TREE_TYPE (TREE_TYPE (cfun->decl))))
5891 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
5893 tree last = last_stmt (e->src);
5894 if (TREE_CODE (last) == RETURN_EXPR
5895 && TREE_OPERAND (last, 0) == NULL)
5897 #ifdef USE_MAPPED_LOCATION
5898 location = EXPR_LOCATION (last);
5899 if (location == UNKNOWN_LOCATION)
5900 location = cfun->function_end_locus;
5901 warning ("%Hcontrol reaches end of non-void function", &location);
5903 locus = EXPR_LOCUS (last);
5905 locus = &cfun->function_end_locus;
5906 warning ("%Hcontrol reaches end of non-void function", locus);
5908 TREE_NO_WARNING (cfun->decl) = 1;
5916 /* Given a basic block B which ends with a conditional and has
5917 precisely two successors, determine which of the edges is taken if
5918 the conditional is true and which is taken if the conditional is
5919 false. Set TRUE_EDGE and FALSE_EDGE appropriately. */
5922 extract_true_false_edges_from_block (basic_block b,
5926 edge e = EDGE_SUCC (b, 0);
5928 if (e->flags & EDGE_TRUE_VALUE)
5931 *false_edge = EDGE_SUCC (b, 1);
5936 *true_edge = EDGE_SUCC (b, 1);
5940 struct tree_opt_pass pass_warn_function_return =
5944 execute_warn_function_return, /* execute */
5947 0, /* static_pass_number */
5949 PROP_cfg, /* properties_required */
5950 0, /* properties_provided */
5951 0, /* properties_destroyed */
5952 0, /* todo_flags_start */
5953 0, /* todo_flags_finish */
5957 #include "gt-tree-cfg.h"