1 /* Control flow functions for trees.
2 Copyright (C) 2001, 2002, 2003, 2004 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"
47 /* This file contains functions for building the Control Flow Graph (CFG)
48 for a function tree. */
50 /* Local declarations. */
52 /* Initial capacity for the basic block array. */
53 static const int initial_cfg_capacity = 20;
55 /* Mapping of labels to their associated blocks. This can greatly speed up
56 building of the CFG in code with lots of gotos. */
57 static GTY(()) varray_type label_to_block_map;
62 long num_merged_labels;
65 static struct cfg_stats_d cfg_stats;
67 /* Nonzero if we found a computed goto while building basic blocks. */
68 static bool found_computed_goto;
70 /* Basic blocks and flowgraphs. */
71 static basic_block create_bb (void *, void *, basic_block);
72 static void create_block_annotation (basic_block);
73 static void free_blocks_annotations (void);
74 static void clear_blocks_annotations (void);
75 static void make_blocks (tree);
76 static void factor_computed_gotos (void);
79 static void make_edges (void);
80 static void make_ctrl_stmt_edges (basic_block);
81 static void make_exit_edges (basic_block);
82 static void make_cond_expr_edges (basic_block);
83 static void make_switch_expr_edges (basic_block);
84 static void make_goto_expr_edges (basic_block);
85 static edge tree_redirect_edge_and_branch (edge, basic_block);
86 static edge tree_try_redirect_by_replacing_jump (edge, basic_block);
87 static void split_critical_edges (void);
89 /* Various helpers. */
90 static inline bool stmt_starts_bb_p (tree, tree);
91 static int tree_verify_flow_info (void);
92 static void tree_make_forwarder_block (edge);
93 static bool thread_jumps (void);
94 static bool tree_forwarder_block_p (basic_block);
95 static void bsi_commit_edge_inserts_1 (edge e);
96 static void tree_cfg2vcg (FILE *);
98 /* Flowgraph optimization and cleanup. */
99 static void tree_merge_blocks (basic_block, basic_block);
100 static bool tree_can_merge_blocks_p (basic_block, basic_block);
101 static void remove_bb (basic_block);
102 static void group_case_labels (void);
103 static void cleanup_dead_labels (void);
104 static bool cleanup_control_flow (void);
105 static bool cleanup_control_expr_graph (basic_block, block_stmt_iterator);
106 static edge find_taken_edge_cond_expr (basic_block, tree);
107 static edge find_taken_edge_switch_expr (basic_block, tree);
108 static tree find_case_label_for_value (tree, tree);
109 static bool phi_alternatives_equal (basic_block, edge, edge);
112 /*---------------------------------------------------------------------------
114 ---------------------------------------------------------------------------*/
116 /* Entry point to the CFG builder for trees. TP points to the list of
117 statements to be added to the flowgraph. */
120 build_tree_cfg (tree *tp)
122 /* Register specific tree functions. */
123 tree_register_cfg_hooks ();
125 /* Initialize rbi_pool. */
128 /* Initialize the basic block array. */
131 last_basic_block = 0;
132 VARRAY_BB_INIT (basic_block_info, initial_cfg_capacity, "basic_block_info");
133 memset ((void *) &cfg_stats, 0, sizeof (cfg_stats));
135 /* Build a mapping of labels to their associated blocks. */
136 VARRAY_BB_INIT (label_to_block_map, initial_cfg_capacity,
137 "label to block map");
139 ENTRY_BLOCK_PTR->next_bb = EXIT_BLOCK_PTR;
140 EXIT_BLOCK_PTR->prev_bb = ENTRY_BLOCK_PTR;
142 found_computed_goto = 0;
145 /* Computed gotos are hell to deal with, especially if there are
146 lots of them with a large number of destinations. So we factor
147 them to a common computed goto location before we build the
148 edge list. After we convert back to normal form, we will un-factor
149 the computed gotos since factoring introduces an unwanted jump. */
150 if (found_computed_goto)
151 factor_computed_gotos ();
153 /* Make sure there is always at least one block, even if its empty. */
154 if (n_basic_blocks == 0)
155 create_empty_bb (ENTRY_BLOCK_PTR);
157 create_block_annotation (ENTRY_BLOCK_PTR);
158 create_block_annotation (EXIT_BLOCK_PTR);
160 /* Adjust the size of the array. */
161 VARRAY_GROW (basic_block_info, n_basic_blocks);
163 /* To speed up statement iterator walks, we first purge dead labels. */
164 cleanup_dead_labels ();
166 /* Group case nodes to reduce the number of edges.
167 We do this after cleaning up dead labels because otherwise we miss
168 a lot of obvious case merging opportunities. */
169 group_case_labels ();
171 /* Create the edges of the flowgraph. */
174 /* Debugging dumps. */
176 /* Write the flowgraph to a VCG file. */
178 int local_dump_flags;
179 FILE *dump_file = dump_begin (TDI_vcg, &local_dump_flags);
182 tree_cfg2vcg (dump_file);
183 dump_end (TDI_vcg, dump_file);
187 /* Dump a textual representation of the flowgraph. */
189 dump_tree_cfg (dump_file, dump_flags);
193 execute_build_cfg (void)
195 build_tree_cfg (&DECL_SAVED_TREE (current_function_decl));
198 struct tree_opt_pass pass_build_cfg =
202 execute_build_cfg, /* execute */
205 0, /* static_pass_number */
206 TV_TREE_CFG, /* tv_id */
207 PROP_gimple_leh, /* properties_required */
208 PROP_cfg, /* properties_provided */
209 0, /* properties_destroyed */
210 0, /* todo_flags_start */
211 TODO_verify_stmts /* todo_flags_finish */
214 /* Search the CFG for any computed gotos. If found, factor them to a
215 common computed goto site. Also record the location of that site so
216 that we can un-factor the gotos after we have converted back to
220 factor_computed_gotos (void)
223 tree factored_label_decl = NULL;
225 tree factored_computed_goto_label = NULL;
226 tree factored_computed_goto = NULL;
228 /* We know there are one or more computed gotos in this function.
229 Examine the last statement in each basic block to see if the block
230 ends with a computed goto. */
234 block_stmt_iterator bsi = bsi_last (bb);
239 last = bsi_stmt (bsi);
241 /* Ignore the computed goto we create when we factor the original
243 if (last == factored_computed_goto)
246 /* If the last statement is a computed goto, factor it. */
247 if (computed_goto_p (last))
251 /* The first time we find a computed goto we need to create
252 the factored goto block and the variable each original
253 computed goto will use for their goto destination. */
254 if (! factored_computed_goto)
256 basic_block new_bb = create_empty_bb (bb);
257 block_stmt_iterator new_bsi = bsi_start (new_bb);
259 /* Create the destination of the factored goto. Each original
260 computed goto will put its desired destination into this
261 variable and jump to the label we create immediately
263 var = create_tmp_var (ptr_type_node, "gotovar");
265 /* Build a label for the new block which will contain the
266 factored computed goto. */
267 factored_label_decl = create_artificial_label ();
268 factored_computed_goto_label
269 = build1 (LABEL_EXPR, void_type_node, factored_label_decl);
270 bsi_insert_after (&new_bsi, factored_computed_goto_label,
273 /* Build our new computed goto. */
274 factored_computed_goto = build1 (GOTO_EXPR, void_type_node, var);
275 bsi_insert_after (&new_bsi, factored_computed_goto,
279 /* Copy the original computed goto's destination into VAR. */
280 assignment = build (MODIFY_EXPR, ptr_type_node,
281 var, GOTO_DESTINATION (last));
282 bsi_insert_before (&bsi, assignment, BSI_SAME_STMT);
284 /* And re-vector the computed goto to the new destination. */
285 GOTO_DESTINATION (last) = factored_label_decl;
291 /* Create annotations for a single basic block. */
294 create_block_annotation (basic_block bb)
296 /* Verify that the tree_annotations field is clear. */
297 if (bb->tree_annotations)
299 bb->tree_annotations = ggc_alloc_cleared (sizeof (struct bb_ann_d));
303 /* Free the annotations for all the basic blocks. */
305 static void free_blocks_annotations (void)
307 clear_blocks_annotations ();
311 /* Clear the annotations for all the basic blocks. */
314 clear_blocks_annotations (void)
318 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb)
319 bb->tree_annotations = NULL;
323 /* Build a flowgraph for the statement_list STMT_LIST. */
326 make_blocks (tree stmt_list)
328 tree_stmt_iterator i = tsi_start (stmt_list);
330 bool start_new_block = true;
331 bool first_stmt_of_list = true;
332 basic_block bb = ENTRY_BLOCK_PTR;
334 while (!tsi_end_p (i))
341 /* If the statement starts a new basic block or if we have determined
342 in a previous pass that we need to create a new block for STMT, do
344 if (start_new_block || stmt_starts_bb_p (stmt, prev_stmt))
346 if (!first_stmt_of_list)
347 stmt_list = tsi_split_statement_list_before (&i);
348 bb = create_basic_block (stmt_list, NULL, bb);
349 start_new_block = false;
352 /* Now add STMT to BB and create the subgraphs for special statement
354 set_bb_for_stmt (stmt, bb);
356 if (computed_goto_p (stmt))
357 found_computed_goto = true;
359 /* If STMT is a basic block terminator, set START_NEW_BLOCK for the
361 if (stmt_ends_bb_p (stmt))
362 start_new_block = true;
365 first_stmt_of_list = false;
370 /* Create and return a new empty basic block after bb AFTER. */
373 create_bb (void *h, void *e, basic_block after)
380 /* Create and initialize a new basic block. */
382 memset (bb, 0, sizeof (*bb));
384 bb->index = last_basic_block;
386 bb->stmt_list = h ? h : alloc_stmt_list ();
388 /* Add the new block to the linked list of blocks. */
389 link_block (bb, after);
391 /* Grow the basic block array if needed. */
392 if ((size_t) last_basic_block == VARRAY_SIZE (basic_block_info))
394 size_t new_size = last_basic_block + (last_basic_block + 3) / 4;
395 VARRAY_GROW (basic_block_info, new_size);
398 /* Add the newly created block to the array. */
399 BASIC_BLOCK (last_basic_block) = bb;
401 create_block_annotation (bb);
406 initialize_bb_rbi (bb);
411 /*---------------------------------------------------------------------------
413 ---------------------------------------------------------------------------*/
415 /* Join all the blocks in the flowgraph. */
422 /* Create an edge from entry to the first block with executable
424 make_edge (ENTRY_BLOCK_PTR, BASIC_BLOCK (0), EDGE_FALLTHRU);
426 /* Traverse basic block array placing edges. */
429 tree first = first_stmt (bb);
430 tree last = last_stmt (bb);
434 /* Edges for statements that always alter flow control. */
435 if (is_ctrl_stmt (last))
436 make_ctrl_stmt_edges (bb);
438 /* Edges for statements that sometimes alter flow control. */
439 if (is_ctrl_altering_stmt (last))
440 make_exit_edges (bb);
443 /* Finally, if no edges were created above, this is a regular
444 basic block that only needs a fallthru edge. */
445 if (bb->succ == NULL)
446 make_edge (bb, bb->next_bb, EDGE_FALLTHRU);
449 /* We do not care about fake edges, so remove any that the CFG
450 builder inserted for completeness. */
451 remove_fake_exit_edges ();
453 /* Clean up the graph and warn for unreachable code. */
458 /* Create edges for control statement at basic block BB. */
461 make_ctrl_stmt_edges (basic_block bb)
463 tree last = last_stmt (bb);
464 tree first = first_stmt (bb);
466 #if defined ENABLE_CHECKING
467 if (last == NULL_TREE)
471 if (TREE_CODE (first) == LABEL_EXPR
472 && DECL_NONLOCAL (LABEL_EXPR_LABEL (first)))
473 make_edge (ENTRY_BLOCK_PTR, bb, EDGE_ABNORMAL);
475 switch (TREE_CODE (last))
478 make_goto_expr_edges (bb);
482 make_edge (bb, EXIT_BLOCK_PTR, 0);
486 make_cond_expr_edges (bb);
490 make_switch_expr_edges (bb);
494 make_eh_edges (last);
495 /* Yet another NORETURN hack. */
496 if (bb->succ == NULL)
497 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
506 /* Create exit edges for statements in block BB that alter the flow of
507 control. Statements that alter the control flow are 'goto', 'return'
508 and calls to non-returning functions. */
511 make_exit_edges (basic_block bb)
513 tree last = last_stmt (bb), op;
515 if (last == NULL_TREE)
518 switch (TREE_CODE (last))
521 /* If this function receives a nonlocal goto, then we need to
522 make edges from this call site to all the nonlocal goto
524 if (TREE_SIDE_EFFECTS (last)
525 && current_function_has_nonlocal_label)
526 make_goto_expr_edges (bb);
528 /* If this statement has reachable exception handlers, then
529 create abnormal edges to them. */
530 make_eh_edges (last);
532 /* Some calls are known not to return. For such calls we create
535 We really need to revamp how we build edges so that it's not
536 such a bloody pain to avoid creating edges for this case since
537 all we do is remove these edges when we're done building the
539 if (call_expr_flags (last) & (ECF_NORETURN | ECF_LONGJMP))
541 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
545 /* Don't forget the fall-thru edge. */
546 make_edge (bb, bb->next_bb, EDGE_FALLTHRU);
550 /* A MODIFY_EXPR may have a CALL_EXPR on its RHS and the CALL_EXPR
551 may have an abnormal edge. Search the RHS for this case and
552 create any required edges. */
553 op = get_call_expr_in (last);
554 if (op && TREE_SIDE_EFFECTS (op)
555 && current_function_has_nonlocal_label)
556 make_goto_expr_edges (bb);
558 make_eh_edges (last);
559 make_edge (bb, bb->next_bb, EDGE_FALLTHRU);
568 /* Create the edges for a COND_EXPR starting at block BB.
569 At this point, both clauses must contain only simple gotos. */
572 make_cond_expr_edges (basic_block bb)
574 tree entry = last_stmt (bb);
575 basic_block then_bb, else_bb;
576 tree then_label, else_label;
578 #if defined ENABLE_CHECKING
579 if (entry == NULL_TREE || TREE_CODE (entry) != COND_EXPR)
583 /* Entry basic blocks for each component. */
584 then_label = GOTO_DESTINATION (COND_EXPR_THEN (entry));
585 else_label = GOTO_DESTINATION (COND_EXPR_ELSE (entry));
586 then_bb = label_to_block (then_label);
587 else_bb = label_to_block (else_label);
589 make_edge (bb, then_bb, EDGE_TRUE_VALUE);
590 make_edge (bb, else_bb, EDGE_FALSE_VALUE);
594 /* Create the edges for a SWITCH_EXPR starting at block BB.
595 At this point, the switch body has been lowered and the
596 SWITCH_LABELS filled in, so this is in effect a multi-way branch. */
599 make_switch_expr_edges (basic_block bb)
601 tree entry = last_stmt (bb);
605 vec = SWITCH_LABELS (entry);
606 n = TREE_VEC_LENGTH (vec);
608 for (i = 0; i < n; ++i)
610 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
611 basic_block label_bb = label_to_block (lab);
612 make_edge (bb, label_bb, 0);
617 /* Return the basic block holding label DEST. */
620 label_to_block (tree dest)
622 int uid = LABEL_DECL_UID (dest);
624 /* We would die hard when faced by undefined label. Emit label to
625 very first basic block. This will hopefully make even the dataflow
626 and undefined variable warnings quite right. */
627 if ((errorcount || sorrycount) && uid < 0)
629 block_stmt_iterator bsi = bsi_start (BASIC_BLOCK (0));
632 stmt = build1 (LABEL_EXPR, void_type_node, dest);
633 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
634 uid = LABEL_DECL_UID (dest);
636 return VARRAY_BB (label_to_block_map, uid);
640 /* Create edges for a goto statement at block BB. */
643 make_goto_expr_edges (basic_block bb)
646 basic_block target_bb;
648 block_stmt_iterator last = bsi_last (bb);
650 goto_t = bsi_stmt (last);
652 /* If the last statement is not a GOTO (i.e., it is a RETURN_EXPR,
653 CALL_EXPR or MODIFY_EXPR), then the edge is an abnormal edge resulting
654 from a nonlocal goto. */
655 if (TREE_CODE (goto_t) != GOTO_EXPR)
657 dest = error_mark_node;
662 dest = GOTO_DESTINATION (goto_t);
665 /* A GOTO to a local label creates normal edges. */
666 if (simple_goto_p (goto_t))
668 edge e = make_edge (bb, label_to_block (dest), EDGE_FALLTHRU);
669 #ifdef USE_MAPPED_LOCATION
670 e->goto_locus = EXPR_LOCATION (goto_t);
672 e->goto_locus = EXPR_LOCUS (goto_t);
678 /* Nothing more to do for nonlocal gotos. */
679 if (TREE_CODE (dest) == LABEL_DECL)
682 /* Computed gotos remain. */
685 /* Look for the block starting with the destination label. In the
686 case of a computed goto, make an edge to any label block we find
688 FOR_EACH_BB (target_bb)
690 block_stmt_iterator bsi;
692 for (bsi = bsi_start (target_bb); !bsi_end_p (bsi); bsi_next (&bsi))
694 tree target = bsi_stmt (bsi);
696 if (TREE_CODE (target) != LABEL_EXPR)
700 /* Computed GOTOs. Make an edge to every label block that has
701 been marked as a potential target for a computed goto. */
702 (FORCED_LABEL (LABEL_EXPR_LABEL (target)) && for_call == 0)
703 /* Nonlocal GOTO target. Make an edge to every label block
704 that has been marked as a potential target for a nonlocal
706 || (DECL_NONLOCAL (LABEL_EXPR_LABEL (target)) && for_call == 1))
708 make_edge (bb, target_bb, EDGE_ABNORMAL);
714 /* Degenerate case of computed goto with no labels. */
715 if (!for_call && !bb->succ)
716 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
720 /*---------------------------------------------------------------------------
722 ---------------------------------------------------------------------------*/
724 /* Remove unreachable blocks and other miscellaneous clean up work. */
727 cleanup_tree_cfg (void)
729 bool something_changed = true;
731 timevar_push (TV_TREE_CLEANUP_CFG);
733 /* These three transformations can cascade, so we iterate on them until
735 while (something_changed)
737 something_changed = cleanup_control_flow ();
738 something_changed |= thread_jumps ();
739 something_changed |= delete_unreachable_blocks ();
742 /* Merging the blocks creates no new opportunities for the other
743 optimizations, so do it here. */
748 #ifdef ENABLE_CHECKING
751 timevar_pop (TV_TREE_CLEANUP_CFG);
755 /* Cleanup useless labels in basic blocks. This is something we wish
756 to do early because it allows us to group case labels before creating
757 the edges for the CFG, and it speeds up block statement iterators in
759 We only run this pass once, running it more than once is probably not
762 /* A map from basic block index to the leading label of that block. */
763 static tree *label_for_bb;
765 /* Callback for for_each_eh_region. Helper for cleanup_dead_labels. */
767 update_eh_label (struct eh_region *region)
769 tree old_label = get_eh_region_tree_label (region);
772 tree new_label = label_for_bb[label_to_block (old_label)->index];
773 set_eh_region_tree_label (region, new_label);
777 /* Given LABEL return the first label in the same basic block. */
779 main_block_label (tree label)
781 basic_block bb = label_to_block (label);
783 /* label_to_block possibly inserted undefined label into the chain. */
784 if (!label_for_bb[bb->index])
785 label_for_bb[bb->index] = label;
786 return label_for_bb[bb->index];
789 /* Cleanup redundant labels. This is a three-steo process:
790 1) Find the leading label for each block.
791 2) Redirect all references to labels to the leading labels.
792 3) Cleanup all useless labels. */
795 cleanup_dead_labels (void)
798 label_for_bb = xcalloc (last_basic_block, sizeof (tree));
800 /* Find a suitable label for each block. We use the first user-defined
801 label is there is one, or otherwise just the first label we see. */
804 block_stmt_iterator i;
806 for (i = bsi_start (bb); !bsi_end_p (i); bsi_next (&i))
808 tree label, stmt = bsi_stmt (i);
810 if (TREE_CODE (stmt) != LABEL_EXPR)
813 label = LABEL_EXPR_LABEL (stmt);
815 /* If we have not yet seen a label for the current block,
816 remember this one and see if there are more labels. */
817 if (! label_for_bb[bb->index])
819 label_for_bb[bb->index] = label;
823 /* If we did see a label for the current block already, but it
824 is an artificially created label, replace it if the current
825 label is a user defined label. */
826 if (! DECL_ARTIFICIAL (label)
827 && DECL_ARTIFICIAL (label_for_bb[bb->index]))
829 label_for_bb[bb->index] = label;
835 /* Now redirect all jumps/branches to the selected label.
836 First do so for each block ending in a control statement. */
839 tree stmt = last_stmt (bb);
843 switch (TREE_CODE (stmt))
847 tree true_branch, false_branch;
849 true_branch = COND_EXPR_THEN (stmt);
850 false_branch = COND_EXPR_ELSE (stmt);
852 GOTO_DESTINATION (true_branch)
853 = main_block_label (GOTO_DESTINATION (true_branch));
854 GOTO_DESTINATION (false_branch)
855 = main_block_label (GOTO_DESTINATION (false_branch));
863 tree vec = SWITCH_LABELS (stmt);
864 size_t n = TREE_VEC_LENGTH (vec);
866 /* Replace all destination labels. */
867 for (i = 0; i < n; ++i)
868 CASE_LABEL (TREE_VEC_ELT (vec, i))
869 = main_block_label (CASE_LABEL (TREE_VEC_ELT (vec, i)));
874 /* We have to handle GOTO_EXPRs until they're removed, and we don't
875 remove them until after we've created the CFG edges. */
877 if (! computed_goto_p (stmt))
879 GOTO_DESTINATION (stmt)
880 = main_block_label (GOTO_DESTINATION (stmt));
889 for_each_eh_region (update_eh_label);
891 /* Finally, purge dead labels. All user-defined labels and labels that
892 can be the target of non-local gotos are preserved. */
895 block_stmt_iterator i;
896 tree label_for_this_bb = label_for_bb[bb->index];
898 if (! label_for_this_bb)
901 for (i = bsi_start (bb); !bsi_end_p (i); )
903 tree label, stmt = bsi_stmt (i);
905 if (TREE_CODE (stmt) != LABEL_EXPR)
908 label = LABEL_EXPR_LABEL (stmt);
910 if (label == label_for_this_bb
911 || ! DECL_ARTIFICIAL (label)
912 || DECL_NONLOCAL (label))
922 /* Look for blocks ending in a multiway branch (a SWITCH_EXPR in GIMPLE),
923 and scan the sorted vector of cases. Combine the ones jumping to the
925 Eg. three separate entries 1: 2: 3: become one entry 1..3: */
928 group_case_labels (void)
934 tree stmt = last_stmt (bb);
935 if (stmt && TREE_CODE (stmt) == SWITCH_EXPR)
937 tree labels = SWITCH_LABELS (stmt);
938 int old_size = TREE_VEC_LENGTH (labels);
939 int i, j, new_size = old_size;
940 tree default_label = TREE_VEC_ELT (labels, old_size - 1);
942 /* Look for possible opportunities to merge cases.
943 Ignore the last element of the label vector because it
944 must be the default case. */
946 while (i < old_size - 2)
948 tree base_case, base_label, base_high, type;
949 base_case = TREE_VEC_ELT (labels, i);
954 base_label = CASE_LABEL (base_case);
956 /* Discard cases that have the same destination as the
958 if (base_label == default_label)
960 TREE_VEC_ELT (labels, i) = NULL_TREE;
965 type = TREE_TYPE (CASE_LOW (base_case));
966 base_high = CASE_HIGH (base_case) ?
967 CASE_HIGH (base_case) : CASE_LOW (base_case);
969 /* Try to merge case labels. Break out when we reach the end
970 of the label vector or when we cannot merge the next case
971 label with the current one. */
972 while (i < old_size - 2)
974 tree merge_case = TREE_VEC_ELT (labels, ++i);
975 tree merge_label = CASE_LABEL (merge_case);
976 tree t = int_const_binop (PLUS_EXPR, base_high,
977 integer_one_node, 1);
979 /* Merge the cases if they jump to the same place,
980 and their ranges are consecutive. */
981 if (merge_label == base_label
982 && tree_int_cst_equal (CASE_LOW (merge_case), t))
984 base_high = CASE_HIGH (merge_case) ?
985 CASE_HIGH (merge_case) : CASE_LOW (merge_case);
986 CASE_HIGH (base_case) = base_high;
987 TREE_VEC_ELT (labels, i) = NULL_TREE;
995 /* Compress the case labels in the label vector, and adjust the
996 length of the vector. */
997 for (i = 0, j = 0; i < new_size; i++)
999 while (! TREE_VEC_ELT (labels, j))
1001 TREE_VEC_ELT (labels, i) = TREE_VEC_ELT (labels, j++);
1003 TREE_VEC_LENGTH (labels) = new_size;
1008 /* Checks whether we can merge block B into block A. */
1011 tree_can_merge_blocks_p (basic_block a, basic_block b)
1014 block_stmt_iterator bsi;
1017 || a->succ->succ_next)
1020 if (a->succ->flags & EDGE_ABNORMAL)
1023 if (a->succ->dest != b)
1026 if (b == EXIT_BLOCK_PTR)
1029 if (b->pred->pred_next)
1032 /* If A ends by a statement causing exceptions or something similar, we
1033 cannot merge the blocks. */
1034 stmt = last_stmt (a);
1035 if (stmt && stmt_ends_bb_p (stmt))
1038 /* Do not allow a block with only a non-local label to be merged. */
1039 if (stmt && TREE_CODE (stmt) == LABEL_EXPR
1040 && DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)))
1043 /* There may be no phi nodes at the start of b. Most of these degenerate
1044 phi nodes should be cleaned up by kill_redundant_phi_nodes. */
1048 /* Do not remove user labels. */
1049 for (bsi = bsi_start (b); !bsi_end_p (bsi); bsi_next (&bsi))
1051 stmt = bsi_stmt (bsi);
1052 if (TREE_CODE (stmt) != LABEL_EXPR)
1054 if (!DECL_ARTIFICIAL (LABEL_EXPR_LABEL (stmt)))
1062 /* Merge block B into block A. */
1065 tree_merge_blocks (basic_block a, basic_block b)
1067 block_stmt_iterator bsi;
1068 tree_stmt_iterator last;
1071 fprintf (dump_file, "Merging blocks %d and %d\n", a->index, b->index);
1073 /* Ensure that B follows A. */
1074 move_block_after (b, a);
1076 if (!(a->succ->flags & EDGE_FALLTHRU))
1080 && stmt_ends_bb_p (last_stmt (a)))
1083 /* Remove labels from B and set bb_for_stmt to A for other statements. */
1084 for (bsi = bsi_start (b); !bsi_end_p (bsi);)
1086 if (TREE_CODE (bsi_stmt (bsi)) == LABEL_EXPR)
1090 set_bb_for_stmt (bsi_stmt (bsi), a);
1095 /* Merge the chains. */
1096 last = tsi_last (a->stmt_list);
1097 tsi_link_after (&last, b->stmt_list, TSI_NEW_STMT);
1098 b->stmt_list = NULL;
1102 /* Walk the function tree removing unnecessary statements.
1104 * Empty statement nodes are removed
1106 * Unnecessary TRY_FINALLY and TRY_CATCH blocks are removed
1108 * Unnecessary COND_EXPRs are removed
1110 * Some unnecessary BIND_EXPRs are removed
1112 Clearly more work could be done. The trick is doing the analysis
1113 and removal fast enough to be a net improvement in compile times.
1115 Note that when we remove a control structure such as a COND_EXPR
1116 BIND_EXPR, or TRY block, we will need to repeat this optimization pass
1117 to ensure we eliminate all the useless code. */
1128 static void remove_useless_stmts_1 (tree *, struct rus_data *);
1131 remove_useless_stmts_warn_notreached (tree stmt)
1133 if (EXPR_HAS_LOCATION (stmt))
1135 location_t loc = EXPR_LOCATION (stmt);
1136 warning ("%Hwill never be executed", &loc);
1140 switch (TREE_CODE (stmt))
1142 case STATEMENT_LIST:
1144 tree_stmt_iterator i;
1145 for (i = tsi_start (stmt); !tsi_end_p (i); tsi_next (&i))
1146 if (remove_useless_stmts_warn_notreached (tsi_stmt (i)))
1152 if (remove_useless_stmts_warn_notreached (COND_EXPR_COND (stmt)))
1154 if (remove_useless_stmts_warn_notreached (COND_EXPR_THEN (stmt)))
1156 if (remove_useless_stmts_warn_notreached (COND_EXPR_ELSE (stmt)))
1160 case TRY_FINALLY_EXPR:
1161 case TRY_CATCH_EXPR:
1162 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt, 0)))
1164 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt, 1)))
1169 return remove_useless_stmts_warn_notreached (CATCH_BODY (stmt));
1170 case EH_FILTER_EXPR:
1171 return remove_useless_stmts_warn_notreached (EH_FILTER_FAILURE (stmt));
1173 return remove_useless_stmts_warn_notreached (BIND_EXPR_BLOCK (stmt));
1176 /* Not a live container. */
1184 remove_useless_stmts_cond (tree *stmt_p, struct rus_data *data)
1186 tree then_clause, else_clause, cond;
1187 bool save_has_label, then_has_label, else_has_label;
1189 save_has_label = data->has_label;
1190 data->has_label = false;
1191 data->last_goto = NULL;
1193 remove_useless_stmts_1 (&COND_EXPR_THEN (*stmt_p), data);
1195 then_has_label = data->has_label;
1196 data->has_label = false;
1197 data->last_goto = NULL;
1199 remove_useless_stmts_1 (&COND_EXPR_ELSE (*stmt_p), data);
1201 else_has_label = data->has_label;
1202 data->has_label = save_has_label | then_has_label | else_has_label;
1205 then_clause = COND_EXPR_THEN (*stmt_p);
1206 else_clause = COND_EXPR_ELSE (*stmt_p);
1207 cond = COND_EXPR_COND (*stmt_p);
1209 /* If neither arm does anything at all, we can remove the whole IF. */
1210 if (!TREE_SIDE_EFFECTS (then_clause) && !TREE_SIDE_EFFECTS (else_clause))
1212 *stmt_p = build_empty_stmt ();
1213 data->repeat = true;
1216 /* If there are no reachable statements in an arm, then we can
1217 zap the entire conditional. */
1218 else if (integer_nonzerop (cond) && !else_has_label)
1220 if (warn_notreached)
1221 remove_useless_stmts_warn_notreached (else_clause);
1222 *stmt_p = then_clause;
1223 data->repeat = true;
1225 else if (integer_zerop (cond) && !then_has_label)
1227 if (warn_notreached)
1228 remove_useless_stmts_warn_notreached (then_clause);
1229 *stmt_p = else_clause;
1230 data->repeat = true;
1233 /* Check a couple of simple things on then/else with single stmts. */
1236 tree then_stmt = expr_only (then_clause);
1237 tree else_stmt = expr_only (else_clause);
1239 /* Notice branches to a common destination. */
1240 if (then_stmt && else_stmt
1241 && TREE_CODE (then_stmt) == GOTO_EXPR
1242 && TREE_CODE (else_stmt) == GOTO_EXPR
1243 && (GOTO_DESTINATION (then_stmt) == GOTO_DESTINATION (else_stmt)))
1245 *stmt_p = then_stmt;
1246 data->repeat = true;
1249 /* If the THEN/ELSE clause merely assigns a value to a variable or
1250 parameter which is already known to contain that value, then
1251 remove the useless THEN/ELSE clause. */
1252 else if (TREE_CODE (cond) == VAR_DECL || TREE_CODE (cond) == PARM_DECL)
1255 && TREE_CODE (else_stmt) == MODIFY_EXPR
1256 && TREE_OPERAND (else_stmt, 0) == cond
1257 && integer_zerop (TREE_OPERAND (else_stmt, 1)))
1258 COND_EXPR_ELSE (*stmt_p) = alloc_stmt_list ();
1260 else if ((TREE_CODE (cond) == EQ_EXPR || TREE_CODE (cond) == NE_EXPR)
1261 && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL
1262 || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL)
1263 && TREE_CONSTANT (TREE_OPERAND (cond, 1)))
1265 tree stmt = (TREE_CODE (cond) == EQ_EXPR
1266 ? then_stmt : else_stmt);
1267 tree *location = (TREE_CODE (cond) == EQ_EXPR
1268 ? &COND_EXPR_THEN (*stmt_p)
1269 : &COND_EXPR_ELSE (*stmt_p));
1272 && TREE_CODE (stmt) == MODIFY_EXPR
1273 && TREE_OPERAND (stmt, 0) == TREE_OPERAND (cond, 0)
1274 && TREE_OPERAND (stmt, 1) == TREE_OPERAND (cond, 1))
1275 *location = alloc_stmt_list ();
1279 /* Protect GOTOs in the arm of COND_EXPRs from being removed. They
1280 would be re-introduced during lowering. */
1281 data->last_goto = NULL;
1286 remove_useless_stmts_tf (tree *stmt_p, struct rus_data *data)
1288 bool save_may_branch, save_may_throw;
1289 bool this_may_branch, this_may_throw;
1291 /* Collect may_branch and may_throw information for the body only. */
1292 save_may_branch = data->may_branch;
1293 save_may_throw = data->may_throw;
1294 data->may_branch = false;
1295 data->may_throw = false;
1296 data->last_goto = NULL;
1298 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 0), data);
1300 this_may_branch = data->may_branch;
1301 this_may_throw = data->may_throw;
1302 data->may_branch |= save_may_branch;
1303 data->may_throw |= save_may_throw;
1304 data->last_goto = NULL;
1306 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 1), data);
1308 /* If the body is empty, then we can emit the FINALLY block without
1309 the enclosing TRY_FINALLY_EXPR. */
1310 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 0)))
1312 *stmt_p = TREE_OPERAND (*stmt_p, 1);
1313 data->repeat = true;
1316 /* If the handler is empty, then we can emit the TRY block without
1317 the enclosing TRY_FINALLY_EXPR. */
1318 else if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 1)))
1320 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1321 data->repeat = true;
1324 /* If the body neither throws, nor branches, then we can safely
1325 string the TRY and FINALLY blocks together. */
1326 else if (!this_may_branch && !this_may_throw)
1328 tree stmt = *stmt_p;
1329 *stmt_p = TREE_OPERAND (stmt, 0);
1330 append_to_statement_list (TREE_OPERAND (stmt, 1), stmt_p);
1331 data->repeat = true;
1337 remove_useless_stmts_tc (tree *stmt_p, struct rus_data *data)
1339 bool save_may_throw, this_may_throw;
1340 tree_stmt_iterator i;
1343 /* Collect may_throw information for the body only. */
1344 save_may_throw = data->may_throw;
1345 data->may_throw = false;
1346 data->last_goto = NULL;
1348 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 0), data);
1350 this_may_throw = data->may_throw;
1351 data->may_throw = save_may_throw;
1353 /* If the body cannot throw, then we can drop the entire TRY_CATCH_EXPR. */
1354 if (!this_may_throw)
1356 if (warn_notreached)
1357 remove_useless_stmts_warn_notreached (TREE_OPERAND (*stmt_p, 1));
1358 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1359 data->repeat = true;
1363 /* Process the catch clause specially. We may be able to tell that
1364 no exceptions propagate past this point. */
1366 this_may_throw = true;
1367 i = tsi_start (TREE_OPERAND (*stmt_p, 1));
1368 stmt = tsi_stmt (i);
1369 data->last_goto = NULL;
1371 switch (TREE_CODE (stmt))
1374 for (; !tsi_end_p (i); tsi_next (&i))
1376 stmt = tsi_stmt (i);
1377 /* If we catch all exceptions, then the body does not
1378 propagate exceptions past this point. */
1379 if (CATCH_TYPES (stmt) == NULL)
1380 this_may_throw = false;
1381 data->last_goto = NULL;
1382 remove_useless_stmts_1 (&CATCH_BODY (stmt), data);
1386 case EH_FILTER_EXPR:
1387 if (EH_FILTER_MUST_NOT_THROW (stmt))
1388 this_may_throw = false;
1389 else if (EH_FILTER_TYPES (stmt) == NULL)
1390 this_may_throw = false;
1391 remove_useless_stmts_1 (&EH_FILTER_FAILURE (stmt), data);
1395 /* Otherwise this is a cleanup. */
1396 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 1), data);
1398 /* If the cleanup is empty, then we can emit the TRY block without
1399 the enclosing TRY_CATCH_EXPR. */
1400 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 1)))
1402 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1403 data->repeat = true;
1407 data->may_throw |= this_may_throw;
1412 remove_useless_stmts_bind (tree *stmt_p, struct rus_data *data)
1416 /* First remove anything underneath the BIND_EXPR. */
1417 remove_useless_stmts_1 (&BIND_EXPR_BODY (*stmt_p), data);
1419 /* If the BIND_EXPR has no variables, then we can pull everything
1420 up one level and remove the BIND_EXPR, unless this is the toplevel
1421 BIND_EXPR for the current function or an inlined function.
1423 When this situation occurs we will want to apply this
1424 optimization again. */
1425 block = BIND_EXPR_BLOCK (*stmt_p);
1426 if (BIND_EXPR_VARS (*stmt_p) == NULL_TREE
1427 && *stmt_p != DECL_SAVED_TREE (current_function_decl)
1429 || ! BLOCK_ABSTRACT_ORIGIN (block)
1430 || (TREE_CODE (BLOCK_ABSTRACT_ORIGIN (block))
1433 *stmt_p = BIND_EXPR_BODY (*stmt_p);
1434 data->repeat = true;
1440 remove_useless_stmts_goto (tree *stmt_p, struct rus_data *data)
1442 tree dest = GOTO_DESTINATION (*stmt_p);
1444 data->may_branch = true;
1445 data->last_goto = NULL;
1447 /* Record the last goto expr, so that we can delete it if unnecessary. */
1448 if (TREE_CODE (dest) == LABEL_DECL)
1449 data->last_goto = stmt_p;
1454 remove_useless_stmts_label (tree *stmt_p, struct rus_data *data)
1456 tree label = LABEL_EXPR_LABEL (*stmt_p);
1458 data->has_label = true;
1460 /* We do want to jump across non-local label receiver code. */
1461 if (DECL_NONLOCAL (label))
1462 data->last_goto = NULL;
1464 else if (data->last_goto && GOTO_DESTINATION (*data->last_goto) == label)
1466 *data->last_goto = build_empty_stmt ();
1467 data->repeat = true;
1470 /* ??? Add something here to delete unused labels. */
1474 /* If the function is "const" or "pure", then clear TREE_SIDE_EFFECTS on its
1475 decl. This allows us to eliminate redundant or useless
1476 calls to "const" functions.
1478 Gimplifier already does the same operation, but we may notice functions
1479 being const and pure once their calls has been gimplified, so we need
1480 to update the flag. */
1483 update_call_expr_flags (tree call)
1485 tree decl = get_callee_fndecl (call);
1488 if (call_expr_flags (call) & (ECF_CONST | ECF_PURE))
1489 TREE_SIDE_EFFECTS (call) = 0;
1490 if (TREE_NOTHROW (decl))
1491 TREE_NOTHROW (call) = 1;
1495 /* T is CALL_EXPR. Set current_function_calls_* flags. */
1498 notice_special_calls (tree t)
1500 int flags = call_expr_flags (t);
1502 if (flags & ECF_MAY_BE_ALLOCA)
1503 current_function_calls_alloca = true;
1504 if (flags & ECF_RETURNS_TWICE)
1505 current_function_calls_setjmp = true;
1509 /* Clear flags set by notice_special_calls. Used by dead code removal
1510 to update the flags. */
1513 clear_special_calls (void)
1515 current_function_calls_alloca = false;
1516 current_function_calls_setjmp = false;
1521 remove_useless_stmts_1 (tree *tp, struct rus_data *data)
1525 switch (TREE_CODE (t))
1528 remove_useless_stmts_cond (tp, data);
1531 case TRY_FINALLY_EXPR:
1532 remove_useless_stmts_tf (tp, data);
1535 case TRY_CATCH_EXPR:
1536 remove_useless_stmts_tc (tp, data);
1540 remove_useless_stmts_bind (tp, data);
1544 remove_useless_stmts_goto (tp, data);
1548 remove_useless_stmts_label (tp, data);
1553 data->last_goto = NULL;
1554 data->may_branch = true;
1559 data->last_goto = NULL;
1560 notice_special_calls (t);
1561 update_call_expr_flags (t);
1562 if (tree_could_throw_p (t))
1563 data->may_throw = true;
1567 data->last_goto = NULL;
1569 op = get_call_expr_in (t);
1572 update_call_expr_flags (op);
1573 notice_special_calls (op);
1575 if (tree_could_throw_p (t))
1576 data->may_throw = true;
1579 case STATEMENT_LIST:
1581 tree_stmt_iterator i = tsi_start (t);
1582 while (!tsi_end_p (i))
1585 if (IS_EMPTY_STMT (t))
1591 remove_useless_stmts_1 (tsi_stmt_ptr (i), data);
1594 if (TREE_CODE (t) == STATEMENT_LIST)
1596 tsi_link_before (&i, t, TSI_SAME_STMT);
1606 data->last_goto = NULL;
1610 data->last_goto = NULL;
1616 remove_useless_stmts (void)
1618 struct rus_data data;
1620 clear_special_calls ();
1624 memset (&data, 0, sizeof (data));
1625 remove_useless_stmts_1 (&DECL_SAVED_TREE (current_function_decl), &data);
1627 while (data.repeat);
1631 struct tree_opt_pass pass_remove_useless_stmts =
1633 "useless", /* name */
1635 remove_useless_stmts, /* execute */
1638 0, /* static_pass_number */
1640 PROP_gimple_any, /* properties_required */
1641 0, /* properties_provided */
1642 0, /* properties_destroyed */
1643 0, /* todo_flags_start */
1644 TODO_dump_func /* todo_flags_finish */
1648 /* Remove obviously useless statements in basic block BB. */
1651 cfg_remove_useless_stmts_bb (basic_block bb)
1653 block_stmt_iterator bsi;
1654 tree stmt = NULL_TREE;
1655 tree cond, var = NULL_TREE, val = NULL_TREE;
1656 struct var_ann_d *ann;
1658 /* Check whether we come here from a condition, and if so, get the
1661 || bb->pred->pred_next
1662 || !(bb->pred->flags & (EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
1665 cond = COND_EXPR_COND (last_stmt (bb->pred->src));
1667 if (TREE_CODE (cond) == VAR_DECL || TREE_CODE (cond) == PARM_DECL)
1670 val = (bb->pred->flags & EDGE_FALSE_VALUE
1671 ? boolean_false_node : boolean_true_node);
1673 else if (TREE_CODE (cond) == TRUTH_NOT_EXPR
1674 && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL
1675 || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL))
1677 var = TREE_OPERAND (cond, 0);
1678 val = (bb->pred->flags & EDGE_FALSE_VALUE
1679 ? boolean_true_node : boolean_false_node);
1683 if (bb->pred->flags & EDGE_FALSE_VALUE)
1684 cond = invert_truthvalue (cond);
1685 if (TREE_CODE (cond) == EQ_EXPR
1686 && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL
1687 || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL)
1688 && (TREE_CODE (TREE_OPERAND (cond, 1)) == VAR_DECL
1689 || TREE_CODE (TREE_OPERAND (cond, 1)) == PARM_DECL
1690 || TREE_CONSTANT (TREE_OPERAND (cond, 1))))
1692 var = TREE_OPERAND (cond, 0);
1693 val = TREE_OPERAND (cond, 1);
1699 /* Only work for normal local variables. */
1700 ann = var_ann (var);
1703 || TREE_ADDRESSABLE (var))
1706 if (! TREE_CONSTANT (val))
1708 ann = var_ann (val);
1711 || TREE_ADDRESSABLE (val))
1715 /* Ignore floating point variables, since comparison behaves weird for
1717 if (FLOAT_TYPE_P (TREE_TYPE (var)))
1720 for (bsi = bsi_start (bb); !bsi_end_p (bsi);)
1722 stmt = bsi_stmt (bsi);
1724 /* If the THEN/ELSE clause merely assigns a value to a variable/parameter
1725 which is already known to contain that value, then remove the useless
1726 THEN/ELSE clause. */
1727 if (TREE_CODE (stmt) == MODIFY_EXPR
1728 && TREE_OPERAND (stmt, 0) == var
1729 && operand_equal_p (val, TREE_OPERAND (stmt, 1), 0))
1735 /* Invalidate the var if we encounter something that could modify it. */
1736 if (TREE_CODE (stmt) == ASM_EXPR
1737 || (TREE_CODE (stmt) == MODIFY_EXPR
1738 && TREE_OPERAND (stmt, 0) == var))
1746 /* A CFG-aware version of remove_useless_stmts. */
1749 cfg_remove_useless_stmts (void)
1753 #ifdef ENABLE_CHECKING
1754 verify_flow_info ();
1759 cfg_remove_useless_stmts_bb (bb);
1764 /* Remove PHI nodes associated with basic block BB and all edges out of BB. */
1767 remove_phi_nodes_and_edges_for_unreachable_block (basic_block bb)
1771 /* Since this block is no longer reachable, we can just delete all
1772 of its PHI nodes. */
1773 phi = phi_nodes (bb);
1776 tree next = PHI_CHAIN (phi);
1777 remove_phi_node (phi, NULL_TREE, bb);
1781 /* Remove edges to BB's successors. */
1782 while (bb->succ != NULL)
1783 ssa_remove_edge (bb->succ);
1787 /* Remove statements of basic block BB. */
1790 remove_bb (basic_block bb)
1792 block_stmt_iterator i;
1793 source_locus loc = 0;
1797 fprintf (dump_file, "Removing basic block %d\n", bb->index);
1798 if (dump_flags & TDF_DETAILS)
1800 dump_bb (bb, dump_file, 0);
1801 fprintf (dump_file, "\n");
1805 /* Remove all the instructions in the block. */
1806 for (i = bsi_start (bb); !bsi_end_p (i); bsi_remove (&i))
1808 tree stmt = bsi_stmt (i);
1810 set_bb_for_stmt (stmt, NULL);
1812 /* Don't warn for removed gotos. Gotos are often removed due to
1813 jump threading, thus resulting in bogus warnings. Not great,
1814 since this way we lose warnings for gotos in the original
1815 program that are indeed unreachable. */
1816 if (TREE_CODE (stmt) != GOTO_EXPR && EXPR_HAS_LOCATION (stmt) && !loc)
1817 #ifdef USE_MAPPED_LOCATION
1818 loc = EXPR_LOCATION (stmt);
1820 loc = EXPR_LOCUS (stmt);
1824 /* If requested, give a warning that the first statement in the
1825 block is unreachable. We walk statements backwards in the
1826 loop above, so the last statement we process is the first statement
1828 if (warn_notreached && loc)
1829 #ifdef USE_MAPPED_LOCATION
1830 warning ("%Hwill never be executed", &loc);
1832 warning ("%Hwill never be executed", loc);
1835 remove_phi_nodes_and_edges_for_unreachable_block (bb);
1839 /* Examine BB to determine if it is a forwarding block (a block which only
1840 transfers control to a new destination). If BB is a forwarding block,
1841 then return the edge leading to the ultimate destination. */
1844 tree_block_forwards_to (basic_block bb)
1846 block_stmt_iterator bsi;
1847 bb_ann_t ann = bb_ann (bb);
1850 /* If this block is not forwardable, then avoid useless work. */
1851 if (! ann->forwardable)
1854 /* Set this block to not be forwardable. This prevents infinite loops since
1855 any block currently under examination is considered non-forwardable. */
1856 ann->forwardable = 0;
1858 /* No forwarding is possible if this block is a special block (ENTRY/EXIT),
1859 this block has more than one successor, this block's single successor is
1860 reached via an abnormal edge, this block has phi nodes, or this block's
1861 single successor has phi nodes. */
1862 if (bb == EXIT_BLOCK_PTR
1863 || bb == ENTRY_BLOCK_PTR
1865 || bb->succ->succ_next
1866 || bb->succ->dest == EXIT_BLOCK_PTR
1867 || (bb->succ->flags & EDGE_ABNORMAL) != 0
1869 || phi_nodes (bb->succ->dest))
1872 /* Walk past any labels at the start of this block. */
1873 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
1875 stmt = bsi_stmt (bsi);
1876 if (TREE_CODE (stmt) != LABEL_EXPR)
1880 /* If we reached the end of this block we may be able to optimize this
1882 if (bsi_end_p (bsi))
1886 /* Recursive call to pick up chains of forwarding blocks. */
1887 dest = tree_block_forwards_to (bb->succ->dest);
1889 /* If none found, we forward to bb->succ at minimum. */
1893 ann->forwardable = 1;
1897 /* No forwarding possible. */
1902 /* Try to remove superfluous control structures. */
1905 cleanup_control_flow (void)
1908 block_stmt_iterator bsi;
1909 bool retval = false;
1914 bsi = bsi_last (bb);
1916 if (bsi_end_p (bsi))
1919 stmt = bsi_stmt (bsi);
1920 if (TREE_CODE (stmt) == COND_EXPR
1921 || TREE_CODE (stmt) == SWITCH_EXPR)
1922 retval |= cleanup_control_expr_graph (bb, bsi);
1928 /* Disconnect an unreachable block in the control expression starting
1932 cleanup_control_expr_graph (basic_block bb, block_stmt_iterator bsi)
1935 bool retval = false;
1936 tree expr = bsi_stmt (bsi), val;
1938 if (bb->succ->succ_next)
1942 switch (TREE_CODE (expr))
1945 val = COND_EXPR_COND (expr);
1949 val = SWITCH_COND (expr);
1950 if (TREE_CODE (val) != INTEGER_CST)
1958 taken_edge = find_taken_edge (bb, val);
1962 /* Remove all the edges except the one that is always executed. */
1963 for (e = bb->succ; e; e = next)
1965 next = e->succ_next;
1966 if (e != taken_edge)
1968 taken_edge->probability += e->probability;
1969 taken_edge->count += e->count;
1970 ssa_remove_edge (e);
1974 if (taken_edge->probability > REG_BR_PROB_BASE)
1975 taken_edge->probability = REG_BR_PROB_BASE;
1978 taken_edge = bb->succ;
1981 taken_edge->flags = EDGE_FALLTHRU;
1983 /* We removed some paths from the cfg. */
1984 if (dom_computed[CDI_DOMINATORS] >= DOM_CONS_OK)
1985 dom_computed[CDI_DOMINATORS] = DOM_CONS_OK;
1991 /* Given a control block BB and a predicate VAL, return the edge that
1992 will be taken out of the block. If VAL does not match a unique
1993 edge, NULL is returned. */
1996 find_taken_edge (basic_block bb, tree val)
2000 stmt = last_stmt (bb);
2002 #if defined ENABLE_CHECKING
2003 if (stmt == NULL_TREE || !is_ctrl_stmt (stmt))
2007 /* If VAL is a predicate of the form N RELOP N, where N is an
2008 SSA_NAME, we can always determine its truth value (except when
2009 doing floating point comparisons that may involve NaNs). */
2011 && TREE_CODE_CLASS (TREE_CODE (val)) == '<'
2012 && TREE_OPERAND (val, 0) == TREE_OPERAND (val, 1)
2013 && TREE_CODE (TREE_OPERAND (val, 0)) == SSA_NAME
2014 && (TREE_CODE (TREE_TYPE (TREE_OPERAND (val, 0))) != REAL_TYPE
2015 || !HONOR_NANS (TYPE_MODE (TREE_TYPE (TREE_OPERAND (val, 0))))))
2017 enum tree_code code = TREE_CODE (val);
2019 if (code == EQ_EXPR || code == LE_EXPR || code == GE_EXPR)
2020 val = boolean_true_node;
2021 else if (code == LT_EXPR || code == GT_EXPR || code == NE_EXPR)
2022 val = boolean_false_node;
2025 /* If VAL is not a constant, we can't determine which edge might
2027 if (val == NULL || !really_constant_p (val))
2030 if (TREE_CODE (stmt) == COND_EXPR)
2031 return find_taken_edge_cond_expr (bb, val);
2033 if (TREE_CODE (stmt) == SWITCH_EXPR)
2034 return find_taken_edge_switch_expr (bb, val);
2040 /* Given a constant value VAL and the entry block BB to a COND_EXPR
2041 statement, determine which of the two edges will be taken out of the
2042 block. Return NULL if either edge may be taken. */
2045 find_taken_edge_cond_expr (basic_block bb, tree val)
2047 edge true_edge, false_edge;
2049 extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
2051 /* If both edges of the branch lead to the same basic block, it doesn't
2052 matter which edge is taken. */
2053 if (true_edge->dest == false_edge->dest)
2056 /* Otherwise, try to determine which branch of the if() will be taken.
2057 If VAL is a constant but it can't be reduced to a 0 or a 1, then
2058 we don't really know which edge will be taken at runtime. This
2059 may happen when comparing addresses (e.g., if (&var1 == 4)). */
2060 if (integer_nonzerop (val))
2062 else if (integer_zerop (val))
2069 /* Given a constant value VAL and the entry block BB to a SWITCH_EXPR
2070 statement, determine which edge will be taken out of the block. Return
2071 NULL if any edge may be taken. */
2074 find_taken_edge_switch_expr (basic_block bb, tree val)
2076 tree switch_expr, taken_case;
2077 basic_block dest_bb;
2080 if (TREE_CODE (val) != INTEGER_CST)
2083 switch_expr = last_stmt (bb);
2084 taken_case = find_case_label_for_value (switch_expr, val);
2085 dest_bb = label_to_block (CASE_LABEL (taken_case));
2087 e = find_edge (bb, dest_bb);
2094 /* Return the CASE_LABEL_EXPR that SWITCH_EXPR will take for VAL.
2095 We can make optimal use here of the fact that the case labels are
2096 sorted: We can do a binary search for a case matching VAL. */
2099 find_case_label_for_value (tree switch_expr, tree val)
2101 tree vec = SWITCH_LABELS (switch_expr);
2102 size_t low, high, n = TREE_VEC_LENGTH (vec);
2103 tree default_case = TREE_VEC_ELT (vec, n - 1);
2105 for (low = -1, high = n - 1; high - low > 1; )
2107 size_t i = (high + low) / 2;
2108 tree t = TREE_VEC_ELT (vec, i);
2111 /* Cache the result of comparing CASE_LOW and val. */
2112 cmp = tree_int_cst_compare (CASE_LOW (t), val);
2119 if (CASE_HIGH (t) == NULL)
2121 /* A singe-valued case label. */
2127 /* A case range. We can only handle integer ranges. */
2128 if (cmp <= 0 && tree_int_cst_compare (CASE_HIGH (t), val) >= 0)
2133 return default_case;
2137 /* If all the PHI nodes in DEST have alternatives for E1 and E2 and
2138 those alternatives are equal in each of the PHI nodes, then return
2139 true, else return false. */
2142 phi_alternatives_equal (basic_block dest, edge e1, edge e2)
2144 tree phi, val1, val2;
2147 for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi))
2149 n1 = phi_arg_from_edge (phi, e1);
2150 n2 = phi_arg_from_edge (phi, e2);
2152 #ifdef ENABLE_CHECKING
2153 if (n1 < 0 || n2 < 0)
2157 val1 = PHI_ARG_DEF (phi, n1);
2158 val2 = PHI_ARG_DEF (phi, n2);
2160 if (!operand_equal_p (val1, val2, 0))
2168 /* Computing the Dominance Frontier:
2170 As described in Morgan, section 3.5, this may be done simply by
2171 walking the dominator tree bottom-up, computing the frontier for
2172 the children before the parent. When considering a block B,
2173 there are two cases:
2175 (1) A flow graph edge leaving B that does not lead to a child
2176 of B in the dominator tree must be a block that is either equal
2177 to B or not dominated by B. Such blocks belong in the frontier
2180 (2) Consider a block X in the frontier of one of the children C
2181 of B. If X is not equal to B and is not dominated by B, it
2182 is in the frontier of B. */
2185 compute_dominance_frontiers_1 (bitmap *frontiers, basic_block bb, sbitmap done)
2190 SET_BIT (done, bb->index);
2192 /* Do the frontier of the children first. Not all children in the
2193 dominator tree (blocks dominated by this one) are children in the
2194 CFG, so check all blocks. */
2195 for (c = first_dom_son (CDI_DOMINATORS, bb);
2197 c = next_dom_son (CDI_DOMINATORS, c))
2199 if (! TEST_BIT (done, c->index))
2200 compute_dominance_frontiers_1 (frontiers, c, done);
2203 /* Find blocks conforming to rule (1) above. */
2204 for (e = bb->succ; e; e = e->succ_next)
2206 if (e->dest == EXIT_BLOCK_PTR)
2208 if (get_immediate_dominator (CDI_DOMINATORS, e->dest) != bb)
2209 bitmap_set_bit (frontiers[bb->index], e->dest->index);
2212 /* Find blocks conforming to rule (2). */
2213 for (c = first_dom_son (CDI_DOMINATORS, bb);
2215 c = next_dom_son (CDI_DOMINATORS, c))
2219 EXECUTE_IF_SET_IN_BITMAP (frontiers[c->index], 0, x,
2221 if (get_immediate_dominator (CDI_DOMINATORS, BASIC_BLOCK (x)) != bb)
2222 bitmap_set_bit (frontiers[bb->index], x);
2229 compute_dominance_frontiers (bitmap *frontiers)
2231 sbitmap done = sbitmap_alloc (last_basic_block);
2233 timevar_push (TV_DOM_FRONTIERS);
2235 sbitmap_zero (done);
2237 compute_dominance_frontiers_1 (frontiers, ENTRY_BLOCK_PTR->succ->dest, done);
2239 sbitmap_free (done);
2241 timevar_pop (TV_DOM_FRONTIERS);
2246 /*---------------------------------------------------------------------------
2248 ---------------------------------------------------------------------------*/
2250 /* Dump tree-specific information of block BB to file OUTF. */
2253 tree_dump_bb (basic_block bb, FILE *outf, int indent)
2255 dump_generic_bb (outf, bb, indent, TDF_VOPS);
2259 /* Dump a basic block on stderr. */
2262 debug_tree_bb (basic_block bb)
2264 dump_bb (bb, stderr, 0);
2268 /* Dump basic block with index N on stderr. */
2271 debug_tree_bb_n (int n)
2273 debug_tree_bb (BASIC_BLOCK (n));
2274 return BASIC_BLOCK (n);
2278 /* Dump the CFG on stderr.
2280 FLAGS are the same used by the tree dumping functions
2281 (see TDF_* in tree.h). */
2284 debug_tree_cfg (int flags)
2286 dump_tree_cfg (stderr, flags);
2290 /* Dump the program showing basic block boundaries on the given FILE.
2292 FLAGS are the same used by the tree dumping functions (see TDF_* in
2296 dump_tree_cfg (FILE *file, int flags)
2298 if (flags & TDF_DETAILS)
2300 const char *funcname
2301 = lang_hooks.decl_printable_name (current_function_decl, 2);
2304 fprintf (file, ";; Function %s\n\n", funcname);
2305 fprintf (file, ";; \n%d basic blocks, %d edges, last basic block %d.\n\n",
2306 n_basic_blocks, n_edges, last_basic_block);
2308 brief_dump_cfg (file);
2309 fprintf (file, "\n");
2312 if (flags & TDF_STATS)
2313 dump_cfg_stats (file);
2315 dump_function_to_file (current_function_decl, file, flags | TDF_BLOCKS);
2319 /* Dump CFG statistics on FILE. */
2322 dump_cfg_stats (FILE *file)
2324 static long max_num_merged_labels = 0;
2325 unsigned long size, total = 0;
2328 const char * const fmt_str = "%-30s%-13s%12s\n";
2329 const char * const fmt_str_1 = "%-30s%13d%11lu%c\n";
2330 const char * const fmt_str_3 = "%-43s%11lu%c\n";
2331 const char *funcname
2332 = lang_hooks.decl_printable_name (current_function_decl, 2);
2335 fprintf (file, "\nCFG Statistics for %s\n\n", funcname);
2337 fprintf (file, "---------------------------------------------------------\n");
2338 fprintf (file, fmt_str, "", " Number of ", "Memory");
2339 fprintf (file, fmt_str, "", " instances ", "used ");
2340 fprintf (file, "---------------------------------------------------------\n");
2342 size = n_basic_blocks * sizeof (struct basic_block_def);
2344 fprintf (file, fmt_str_1, "Basic blocks", n_basic_blocks,
2345 SCALE (size), LABEL (size));
2351 for (e = bb->succ; e; e = e->succ_next)
2354 size = n_edges * sizeof (struct edge_def);
2356 fprintf (file, fmt_str_1, "Edges", n_edges, SCALE (size), LABEL (size));
2358 size = n_basic_blocks * sizeof (struct bb_ann_d);
2360 fprintf (file, fmt_str_1, "Basic block annotations", n_basic_blocks,
2361 SCALE (size), LABEL (size));
2363 fprintf (file, "---------------------------------------------------------\n");
2364 fprintf (file, fmt_str_3, "Total memory used by CFG data", SCALE (total),
2366 fprintf (file, "---------------------------------------------------------\n");
2367 fprintf (file, "\n");
2369 if (cfg_stats.num_merged_labels > max_num_merged_labels)
2370 max_num_merged_labels = cfg_stats.num_merged_labels;
2372 fprintf (file, "Coalesced label blocks: %ld (Max so far: %ld)\n",
2373 cfg_stats.num_merged_labels, max_num_merged_labels);
2375 fprintf (file, "\n");
2379 /* Dump CFG statistics on stderr. Keep extern so that it's always
2380 linked in the final executable. */
2383 debug_cfg_stats (void)
2385 dump_cfg_stats (stderr);
2389 /* Dump the flowgraph to a .vcg FILE. */
2392 tree_cfg2vcg (FILE *file)
2396 const char *funcname
2397 = lang_hooks.decl_printable_name (current_function_decl, 2);
2399 /* Write the file header. */
2400 fprintf (file, "graph: { title: \"%s\"\n", funcname);
2401 fprintf (file, "node: { title: \"ENTRY\" label: \"ENTRY\" }\n");
2402 fprintf (file, "node: { title: \"EXIT\" label: \"EXIT\" }\n");
2404 /* Write blocks and edges. */
2405 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
2407 fprintf (file, "edge: { sourcename: \"ENTRY\" targetname: \"%d\"",
2410 if (e->flags & EDGE_FAKE)
2411 fprintf (file, " linestyle: dotted priority: 10");
2413 fprintf (file, " linestyle: solid priority: 100");
2415 fprintf (file, " }\n");
2421 enum tree_code head_code, end_code;
2422 const char *head_name, *end_name;
2425 tree first = first_stmt (bb);
2426 tree last = last_stmt (bb);
2430 head_code = TREE_CODE (first);
2431 head_name = tree_code_name[head_code];
2432 head_line = get_lineno (first);
2435 head_name = "no-statement";
2439 end_code = TREE_CODE (last);
2440 end_name = tree_code_name[end_code];
2441 end_line = get_lineno (last);
2444 end_name = "no-statement";
2446 fprintf (file, "node: { title: \"%d\" label: \"#%d\\n%s (%d)\\n%s (%d)\"}\n",
2447 bb->index, bb->index, head_name, head_line, end_name,
2450 for (e = bb->succ; e; e = e->succ_next)
2452 if (e->dest == EXIT_BLOCK_PTR)
2453 fprintf (file, "edge: { sourcename: \"%d\" targetname: \"EXIT\"", bb->index);
2455 fprintf (file, "edge: { sourcename: \"%d\" targetname: \"%d\"", bb->index, e->dest->index);
2457 if (e->flags & EDGE_FAKE)
2458 fprintf (file, " priority: 10 linestyle: dotted");
2460 fprintf (file, " priority: 100 linestyle: solid");
2462 fprintf (file, " }\n");
2465 if (bb->next_bb != EXIT_BLOCK_PTR)
2469 fputs ("}\n\n", file);
2474 /*---------------------------------------------------------------------------
2475 Miscellaneous helpers
2476 ---------------------------------------------------------------------------*/
2478 /* Return true if T represents a stmt that always transfers control. */
2481 is_ctrl_stmt (tree t)
2483 return (TREE_CODE (t) == COND_EXPR
2484 || TREE_CODE (t) == SWITCH_EXPR
2485 || TREE_CODE (t) == GOTO_EXPR
2486 || TREE_CODE (t) == RETURN_EXPR
2487 || TREE_CODE (t) == RESX_EXPR);
2491 /* Return true if T is a statement that may alter the flow of control
2492 (e.g., a call to a non-returning function). */
2495 is_ctrl_altering_stmt (tree t)
2499 #if defined ENABLE_CHECKING
2504 call = get_call_expr_in (t);
2507 /* A non-pure/const CALL_EXPR alters flow control if the current
2508 function has nonlocal labels. */
2509 if (TREE_SIDE_EFFECTS (call) && current_function_has_nonlocal_label)
2512 /* A CALL_EXPR also alters control flow if it does not return. */
2513 if (call_expr_flags (call) & (ECF_NORETURN | ECF_LONGJMP))
2517 /* If a statement can throw, it alters control flow. */
2518 return tree_can_throw_internal (t);
2522 /* Return true if T is a computed goto. */
2525 computed_goto_p (tree t)
2527 return (TREE_CODE (t) == GOTO_EXPR
2528 && TREE_CODE (GOTO_DESTINATION (t)) != LABEL_DECL);
2532 /* Checks whether EXPR is a simple local goto. */
2535 simple_goto_p (tree expr)
2537 return (TREE_CODE (expr) == GOTO_EXPR
2538 && TREE_CODE (GOTO_DESTINATION (expr)) == LABEL_DECL
2539 && (decl_function_context (GOTO_DESTINATION (expr))
2540 == current_function_decl));
2544 /* Return true if T should start a new basic block. PREV_T is the
2545 statement preceding T. It is used when T is a label or a case label.
2546 Labels should only start a new basic block if their previous statement
2547 wasn't a label. Otherwise, sequence of labels would generate
2548 unnecessary basic blocks that only contain a single label. */
2551 stmt_starts_bb_p (tree t, tree prev_t)
2553 enum tree_code code;
2558 /* LABEL_EXPRs start a new basic block only if the preceding
2559 statement wasn't a label of the same type. This prevents the
2560 creation of consecutive blocks that have nothing but a single
2562 code = TREE_CODE (t);
2563 if (code == LABEL_EXPR)
2565 /* Nonlocal and computed GOTO targets always start a new block. */
2566 if (code == LABEL_EXPR
2567 && (DECL_NONLOCAL (LABEL_EXPR_LABEL (t))
2568 || FORCED_LABEL (LABEL_EXPR_LABEL (t))))
2571 if (prev_t && TREE_CODE (prev_t) == code)
2573 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (prev_t)))
2576 cfg_stats.num_merged_labels++;
2587 /* Return true if T should end a basic block. */
2590 stmt_ends_bb_p (tree t)
2592 return is_ctrl_stmt (t) || is_ctrl_altering_stmt (t);
2596 /* Add gotos that used to be represented implicitly in the CFG. */
2599 disband_implicit_edges (void)
2602 block_stmt_iterator last;
2608 last = bsi_last (bb);
2609 stmt = last_stmt (bb);
2611 if (stmt && TREE_CODE (stmt) == COND_EXPR)
2613 /* Remove superfluous gotos from COND_EXPR branches. Moved
2614 from cfg_remove_useless_stmts here since it violates the
2615 invariants for tree--cfg correspondence and thus fits better
2616 here where we do it anyway. */
2617 for (e = bb->succ; e; e = e->succ_next)
2619 if (e->dest != bb->next_bb)
2622 if (e->flags & EDGE_TRUE_VALUE)
2623 COND_EXPR_THEN (stmt) = build_empty_stmt ();
2624 else if (e->flags & EDGE_FALSE_VALUE)
2625 COND_EXPR_ELSE (stmt) = build_empty_stmt ();
2628 e->flags |= EDGE_FALLTHRU;
2634 if (stmt && TREE_CODE (stmt) == RETURN_EXPR)
2636 /* Remove the RETURN_EXPR if we may fall though to the exit
2639 || bb->succ->succ_next
2640 || bb->succ->dest != EXIT_BLOCK_PTR)
2643 if (bb->next_bb == EXIT_BLOCK_PTR
2644 && !TREE_OPERAND (stmt, 0))
2647 bb->succ->flags |= EDGE_FALLTHRU;
2652 /* There can be no fallthru edge if the last statement is a control
2654 if (stmt && is_ctrl_stmt (stmt))
2657 /* Find a fallthru edge and emit the goto if necessary. */
2658 for (e = bb->succ; e; e = e->succ_next)
2659 if (e->flags & EDGE_FALLTHRU)
2662 if (!e || e->dest == bb->next_bb)
2665 if (e->dest == EXIT_BLOCK_PTR)
2668 label = tree_block_label (e->dest);
2670 stmt = build1 (GOTO_EXPR, void_type_node, label);
2671 #ifdef USE_MAPPED_LOCATION
2672 SET_EXPR_LOCATION (stmt, e->goto_locus);
2674 SET_EXPR_LOCUS (stmt, e->goto_locus);
2676 bsi_insert_after (&last, stmt, BSI_NEW_STMT);
2677 e->flags &= ~EDGE_FALLTHRU;
2681 /* Remove block annotations and other datastructures. */
2684 delete_tree_cfg_annotations (void)
2687 if (n_basic_blocks > 0)
2688 free_blocks_annotations ();
2690 label_to_block_map = NULL;
2697 /* Return the first statement in basic block BB. */
2700 first_stmt (basic_block bb)
2702 block_stmt_iterator i = bsi_start (bb);
2703 return !bsi_end_p (i) ? bsi_stmt (i) : NULL_TREE;
2707 /* Return the last statement in basic block BB. */
2710 last_stmt (basic_block bb)
2712 block_stmt_iterator b = bsi_last (bb);
2713 return !bsi_end_p (b) ? bsi_stmt (b) : NULL_TREE;
2717 /* Return a pointer to the last statement in block BB. */
2720 last_stmt_ptr (basic_block bb)
2722 block_stmt_iterator last = bsi_last (bb);
2723 return !bsi_end_p (last) ? bsi_stmt_ptr (last) : NULL;
2727 /* Return the last statement of an otherwise empty block. Return NULL
2728 if the block is totally empty, or if it contains more than one
2732 last_and_only_stmt (basic_block bb)
2734 block_stmt_iterator i = bsi_last (bb);
2740 last = bsi_stmt (i);
2745 /* Empty statements should no longer appear in the instruction stream.
2746 Everything that might have appeared before should be deleted by
2747 remove_useless_stmts, and the optimizers should just bsi_remove
2748 instead of smashing with build_empty_stmt.
2750 Thus the only thing that should appear here in a block containing
2751 one executable statement is a label. */
2752 prev = bsi_stmt (i);
2753 if (TREE_CODE (prev) == LABEL_EXPR)
2760 /* Mark BB as the basic block holding statement T. */
2763 set_bb_for_stmt (tree t, basic_block bb)
2765 if (TREE_CODE (t) == STATEMENT_LIST)
2767 tree_stmt_iterator i;
2768 for (i = tsi_start (t); !tsi_end_p (i); tsi_next (&i))
2769 set_bb_for_stmt (tsi_stmt (i), bb);
2773 stmt_ann_t ann = get_stmt_ann (t);
2776 /* If the statement is a label, add the label to block-to-labels map
2777 so that we can speed up edge creation for GOTO_EXPRs. */
2778 if (TREE_CODE (t) == LABEL_EXPR)
2782 t = LABEL_EXPR_LABEL (t);
2783 uid = LABEL_DECL_UID (t);
2786 LABEL_DECL_UID (t) = uid = cfun->last_label_uid++;
2787 if (VARRAY_SIZE (label_to_block_map) <= (unsigned) uid)
2788 VARRAY_GROW (label_to_block_map, 3 * uid / 2);
2792 #ifdef ENABLE_CHECKING
2793 /* We're moving an existing label. Make sure that we've
2794 removed it from the old block. */
2795 if (bb && VARRAY_BB (label_to_block_map, uid))
2799 VARRAY_BB (label_to_block_map, uid) = bb;
2805 /* Insert statement (or statement list) T before the statement
2806 pointed-to by iterator I. M specifies how to update iterator I
2807 after insertion (see enum bsi_iterator_update). */
2810 bsi_insert_before (block_stmt_iterator *i, tree t, enum bsi_iterator_update m)
2812 set_bb_for_stmt (t, i->bb);
2814 tsi_link_before (&i->tsi, t, m);
2818 /* Insert statement (or statement list) T after the statement
2819 pointed-to by iterator I. M specifies how to update iterator I
2820 after insertion (see enum bsi_iterator_update). */
2823 bsi_insert_after (block_stmt_iterator *i, tree t, enum bsi_iterator_update m)
2825 set_bb_for_stmt (t, i->bb);
2827 tsi_link_after (&i->tsi, t, m);
2831 /* Remove the statement pointed to by iterator I. The iterator is updated
2832 to the next statement. */
2835 bsi_remove (block_stmt_iterator *i)
2837 tree t = bsi_stmt (*i);
2838 set_bb_for_stmt (t, NULL);
2840 tsi_delink (&i->tsi);
2844 /* Move the statement at FROM so it comes right after the statement at TO. */
2847 bsi_move_after (block_stmt_iterator *from, block_stmt_iterator *to)
2849 tree stmt = bsi_stmt (*from);
2851 bsi_insert_after (to, stmt, BSI_SAME_STMT);
2855 /* Move the statement at FROM so it comes right before the statement at TO. */
2858 bsi_move_before (block_stmt_iterator *from, block_stmt_iterator *to)
2860 tree stmt = bsi_stmt (*from);
2862 bsi_insert_before (to, stmt, BSI_SAME_STMT);
2866 /* Move the statement at FROM to the end of basic block BB. */
2869 bsi_move_to_bb_end (block_stmt_iterator *from, basic_block bb)
2871 block_stmt_iterator last = bsi_last (bb);
2873 /* Have to check bsi_end_p because it could be an empty block. */
2874 if (!bsi_end_p (last) && is_ctrl_stmt (bsi_stmt (last)))
2875 bsi_move_before (from, &last);
2877 bsi_move_after (from, &last);
2881 /* Replace the contents of the statement pointed to by iterator BSI
2882 with STMT. If PRESERVE_EH_INFO is true, the exception handling
2883 information of the original statement is preserved. */
2886 bsi_replace (const block_stmt_iterator *bsi, tree stmt, bool preserve_eh_info)
2889 tree orig_stmt = bsi_stmt (*bsi);
2891 SET_EXPR_LOCUS (stmt, EXPR_LOCUS (orig_stmt));
2892 set_bb_for_stmt (stmt, bsi->bb);
2894 /* Preserve EH region information from the original statement, if
2895 requested by the caller. */
2896 if (preserve_eh_info)
2898 eh_region = lookup_stmt_eh_region (orig_stmt);
2900 add_stmt_to_eh_region (stmt, eh_region);
2903 *bsi_stmt_ptr (*bsi) = stmt;
2908 /* Insert the statement pointed-to by BSI into edge E. Every attempt
2909 is made to place the statement in an existing basic block, but
2910 sometimes that isn't possible. When it isn't possible, the edge is
2911 split and the statement is added to the new block.
2913 In all cases, the returned *BSI points to the correct location. The
2914 return value is true if insertion should be done after the location,
2915 or false if it should be done before the location. */
2918 tree_find_edge_insert_loc (edge e, block_stmt_iterator *bsi)
2920 basic_block dest, src;
2926 /* If the destination has one predecessor which has no PHI nodes,
2927 insert there. Except for the exit block.
2929 The requirement for no PHI nodes could be relaxed. Basically we
2930 would have to examine the PHIs to prove that none of them used
2931 the value set by the statement we want to insert on E. That
2932 hardly seems worth the effort. */
2933 if (dest->pred->pred_next == NULL
2934 && ! phi_nodes (dest)
2935 && dest != EXIT_BLOCK_PTR)
2937 *bsi = bsi_start (dest);
2938 if (bsi_end_p (*bsi))
2941 /* Make sure we insert after any leading labels. */
2942 tmp = bsi_stmt (*bsi);
2943 while (TREE_CODE (tmp) == LABEL_EXPR)
2946 if (bsi_end_p (*bsi))
2948 tmp = bsi_stmt (*bsi);
2951 if (bsi_end_p (*bsi))
2953 *bsi = bsi_last (dest);
2960 /* If the source has one successor, the edge is not abnormal and
2961 the last statement does not end a basic block, insert there.
2962 Except for the entry block. */
2964 if ((e->flags & EDGE_ABNORMAL) == 0
2965 && src->succ->succ_next == NULL
2966 && src != ENTRY_BLOCK_PTR)
2968 *bsi = bsi_last (src);
2969 if (bsi_end_p (*bsi))
2972 tmp = bsi_stmt (*bsi);
2973 if (!stmt_ends_bb_p (tmp))
2976 /* Insert code just before returning the value. We may need to decompose
2977 the return in the case it contains non-trivial operand. */
2978 if (TREE_CODE (tmp) == RETURN_EXPR)
2980 tree op = TREE_OPERAND (tmp, 0);
2981 if (!is_gimple_val (op))
2983 if (TREE_CODE (op) != MODIFY_EXPR)
2985 bsi_insert_before (bsi, op, BSI_NEW_STMT);
2986 TREE_OPERAND (tmp, 0) = TREE_OPERAND (op, 0);
2993 /* Otherwise, create a new basic block, and split this edge. */
2994 dest = split_edge (e);
3000 /* This routine will commit all pending edge insertions, creating any new
3001 basic blocks which are necessary.
3003 If specified, NEW_BLOCKS returns a count of the number of new basic
3004 blocks which were created. */
3007 bsi_commit_edge_inserts (int *new_blocks)
3013 blocks = n_basic_blocks;
3015 bsi_commit_edge_inserts_1 (ENTRY_BLOCK_PTR->succ);
3018 for (e = bb->succ; e; e = e->succ_next)
3019 bsi_commit_edge_inserts_1 (e);
3022 *new_blocks = n_basic_blocks - blocks;
3026 /* Commit insertions pending at edge E. */
3029 bsi_commit_edge_inserts_1 (edge e)
3031 if (PENDING_STMT (e))
3033 block_stmt_iterator bsi;
3034 tree stmt = PENDING_STMT (e);
3036 PENDING_STMT (e) = NULL_TREE;
3038 if (tree_find_edge_insert_loc (e, &bsi))
3039 bsi_insert_after (&bsi, stmt, BSI_NEW_STMT);
3041 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
3046 /* Add STMT to the pending list of edge E. No actual insertion is
3047 made until a call to bsi_commit_edge_inserts () is made. */
3050 bsi_insert_on_edge (edge e, tree stmt)
3052 append_to_statement_list (stmt, &PENDING_STMT (e));
3056 /*---------------------------------------------------------------------------
3057 Tree specific functions for CFG manipulation
3058 ---------------------------------------------------------------------------*/
3060 /* Split a (typically critical) edge EDGE_IN. Return the new block.
3061 Abort on abnormal edges. */
3064 tree_split_edge (edge edge_in)
3066 basic_block new_bb, after_bb, dest, src;
3071 /* Abnormal edges cannot be split. */
3072 if (edge_in->flags & EDGE_ABNORMAL)
3076 dest = edge_in->dest;
3078 /* Place the new block in the block list. Try to keep the new block
3079 near its "logical" location. This is of most help to humans looking
3080 at debugging dumps. */
3081 for (e = dest->pred; e; e = e->pred_next)
3082 if (e->src->next_bb == dest)
3085 after_bb = dest->prev_bb;
3087 after_bb = edge_in->src;
3089 new_bb = create_empty_bb (after_bb);
3090 new_edge = make_edge (new_bb, dest, EDGE_FALLTHRU);
3092 /* Find all the PHI arguments on the original edge, and change them to
3093 the new edge. Do it before redirection, so that the argument does not
3095 for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi))
3097 num_elem = PHI_NUM_ARGS (phi);
3098 for (i = 0; i < num_elem; i++)
3099 if (PHI_ARG_EDGE (phi, i) == edge_in)
3101 PHI_ARG_EDGE (phi, i) = new_edge;
3106 if (!redirect_edge_and_branch (edge_in, new_bb))
3109 if (PENDING_STMT (edge_in))
3116 /* Return true when BB has label LABEL in it. */
3119 has_label_p (basic_block bb, tree label)
3121 block_stmt_iterator bsi;
3123 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3125 tree stmt = bsi_stmt (bsi);
3127 if (TREE_CODE (stmt) != LABEL_EXPR)
3129 if (LABEL_EXPR_LABEL (stmt) == label)
3136 /* Callback for walk_tree, check that all elements with address taken are
3137 properly noticed as such. */
3140 verify_expr (tree *tp, int *walk_subtrees, void *data ATTRIBUTE_UNUSED)
3147 /* Check operand N for being valid GIMPLE and give error MSG if not.
3148 We check for constants explicitly since they are not considered
3149 gimple invariants if they overflowed. */
3150 #define CHECK_OP(N, MSG) \
3151 do { if (TREE_CODE_CLASS (TREE_CODE (TREE_OPERAND (t, N))) != 'c' \
3152 && !is_gimple_val (TREE_OPERAND (t, N))) \
3153 { error (MSG); return TREE_OPERAND (t, N); }} while (0)
3155 switch (TREE_CODE (t))
3158 if (SSA_NAME_IN_FREE_LIST (t))
3160 error ("SSA name in freelist but still referenced");
3166 x = TREE_OPERAND (t, 0);
3167 if (TREE_CODE (x) == BIT_FIELD_REF
3168 && is_gimple_reg (TREE_OPERAND (x, 0)))
3170 error ("GIMPLE register modified with BIT_FIELD_REF");
3176 /* Skip any references (they will be checked when we recurse down the
3177 tree) and ensure that any variable used as a prefix is marked
3179 for (x = TREE_OPERAND (t, 0);
3180 (handled_component_p (x)
3181 || TREE_CODE (x) == REALPART_EXPR
3182 || TREE_CODE (x) == IMAGPART_EXPR);
3183 x = TREE_OPERAND (x, 0))
3186 if (TREE_CODE (x) != VAR_DECL && TREE_CODE (x) != PARM_DECL)
3188 if (!TREE_ADDRESSABLE (x))
3190 error ("address taken, but ADDRESSABLE bit not set");
3196 x = TREE_OPERAND (t, 0);
3197 if (TREE_CODE (TREE_TYPE (x)) != BOOLEAN_TYPE)
3199 error ("non-boolean used in condition");
3206 case FIX_TRUNC_EXPR:
3208 case FIX_FLOOR_EXPR:
3209 case FIX_ROUND_EXPR:
3214 case NON_LVALUE_EXPR:
3215 case TRUTH_NOT_EXPR:
3216 CHECK_OP (0, "Invalid operand to unary operator");
3223 case ARRAY_RANGE_REF:
3225 case VIEW_CONVERT_EXPR:
3226 /* We have a nest of references. Verify that each of the operands
3227 that determine where to reference is either a constant or a variable,
3228 verify that the base is valid, and then show we've already checked
3230 while (TREE_CODE (t) == REALPART_EXPR || TREE_CODE (t) == IMAGPART_EXPR
3231 || handled_component_p (t))
3233 if (TREE_CODE (t) == COMPONENT_REF && TREE_OPERAND (t, 2))
3234 CHECK_OP (2, "Invalid COMPONENT_REF offset operator");
3235 else if (TREE_CODE (t) == ARRAY_REF
3236 || TREE_CODE (t) == ARRAY_RANGE_REF)
3238 CHECK_OP (1, "Invalid array index.");
3239 if (TREE_OPERAND (t, 2))
3240 CHECK_OP (2, "Invalid array lower bound.");
3241 if (TREE_OPERAND (t, 3))
3242 CHECK_OP (3, "Invalid array stride.");
3244 else if (TREE_CODE (t) == BIT_FIELD_REF)
3246 CHECK_OP (1, "Invalid operand to BIT_FIELD_REF");
3247 CHECK_OP (2, "Invalid operand to BIT_FIELD_REF");
3250 t = TREE_OPERAND (t, 0);
3253 if (TREE_CODE_CLASS (TREE_CODE (t)) != 'c'
3254 && !is_gimple_lvalue (t))
3256 error ("Invalid reference prefix.");
3268 case UNORDERED_EXPR:
3279 case TRUNC_DIV_EXPR:
3281 case FLOOR_DIV_EXPR:
3282 case ROUND_DIV_EXPR:
3283 case TRUNC_MOD_EXPR:
3285 case FLOOR_MOD_EXPR:
3286 case ROUND_MOD_EXPR:
3288 case EXACT_DIV_EXPR:
3298 CHECK_OP (0, "Invalid operand to binary operator");
3299 CHECK_OP (1, "Invalid operand to binary operator");
3311 /* Verify STMT, return true if STMT is not in GIMPLE form.
3312 TODO: Implement type checking. */
3315 verify_stmt (tree stmt, bool last_in_block)
3319 if (!is_gimple_stmt (stmt))
3321 error ("Is not a valid GIMPLE statement.");
3325 addr = walk_tree (&stmt, verify_expr, NULL, NULL);
3328 debug_generic_stmt (addr);
3332 /* If the statement is marked as part of an EH region, then it is
3333 expected that the statement could throw. Verify that when we
3334 have optimizations that simplify statements such that we prove
3335 that they cannot throw, that we update other data structures
3337 if (lookup_stmt_eh_region (stmt) >= 0)
3339 if (!tree_could_throw_p (stmt))
3341 error ("Statement marked for throw, but doesn't.");
3344 if (!last_in_block && tree_can_throw_internal (stmt))
3346 error ("Statement marked for throw in middle of block.");
3354 debug_generic_stmt (stmt);
3359 /* Return true when the T can be shared. */
3362 tree_node_can_be_shared (tree t)
3364 if (TYPE_P (t) || DECL_P (t)
3365 /* We check for constants explicitly since they are not considered
3366 gimple invariants if they overflowed. */
3367 || TREE_CODE_CLASS (TREE_CODE (t)) == 'c'
3368 || is_gimple_min_invariant (t)
3369 || TREE_CODE (t) == SSA_NAME)
3372 while (((TREE_CODE (t) == ARRAY_REF || TREE_CODE (t) == ARRAY_RANGE_REF)
3373 /* We check for constants explicitly since they are not considered
3374 gimple invariants if they overflowed. */
3375 && (TREE_CODE_CLASS (TREE_CODE (TREE_OPERAND (t, 1))) == 'c'
3376 || is_gimple_min_invariant (TREE_OPERAND (t, 1))))
3377 || (TREE_CODE (t) == COMPONENT_REF
3378 || TREE_CODE (t) == REALPART_EXPR
3379 || TREE_CODE (t) == IMAGPART_EXPR))
3380 t = TREE_OPERAND (t, 0);
3389 /* Called via walk_trees. Verify tree sharing. */
3392 verify_node_sharing (tree * tp, int *walk_subtrees, void *data)
3394 htab_t htab = (htab_t) data;
3397 if (tree_node_can_be_shared (*tp))
3399 *walk_subtrees = false;
3403 slot = htab_find_slot (htab, *tp, INSERT);
3412 /* Verify the GIMPLE statement chain. */
3418 block_stmt_iterator bsi;
3423 timevar_push (TV_TREE_STMT_VERIFY);
3424 htab = htab_create (37, htab_hash_pointer, htab_eq_pointer, NULL);
3431 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
3433 int phi_num_args = PHI_NUM_ARGS (phi);
3435 for (i = 0; i < phi_num_args; i++)
3437 tree t = PHI_ARG_DEF (phi, i);
3440 /* Addressable variables do have SSA_NAMEs but they
3441 are not considered gimple values. */
3442 if (TREE_CODE (t) != SSA_NAME
3443 && TREE_CODE (t) != FUNCTION_DECL
3444 && !is_gimple_val (t))
3446 error ("PHI def is not a GIMPLE value");
3447 debug_generic_stmt (phi);
3448 debug_generic_stmt (t);
3452 addr = walk_tree (&t, verify_expr, NULL, NULL);
3455 debug_generic_stmt (addr);
3459 addr = walk_tree (&t, verify_node_sharing, htab, NULL);
3462 error ("Incorrect sharing of tree nodes");
3463 debug_generic_stmt (phi);
3464 debug_generic_stmt (addr);
3470 for (bsi = bsi_start (bb); !bsi_end_p (bsi); )
3472 tree stmt = bsi_stmt (bsi);
3474 err |= verify_stmt (stmt, bsi_end_p (bsi));
3475 addr = walk_tree (&stmt, verify_node_sharing, htab, NULL);
3478 error ("Incorrect sharing of tree nodes");
3479 debug_generic_stmt (stmt);
3480 debug_generic_stmt (addr);
3487 internal_error ("verify_stmts failed.");
3490 timevar_pop (TV_TREE_STMT_VERIFY);
3494 /* Verifies that the flow information is OK. */
3497 tree_verify_flow_info (void)
3501 block_stmt_iterator bsi;
3505 if (ENTRY_BLOCK_PTR->stmt_list)
3507 error ("ENTRY_BLOCK has a statement list associated with it\n");
3511 if (EXIT_BLOCK_PTR->stmt_list)
3513 error ("EXIT_BLOCK has a statement list associated with it\n");
3517 for (e = EXIT_BLOCK_PTR->pred; e; e = e->pred_next)
3518 if (e->flags & EDGE_FALLTHRU)
3520 error ("Fallthru to exit from bb %d\n", e->src->index);
3526 bool found_ctrl_stmt = false;
3528 /* Skip labels on the start of basic block. */
3529 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3531 if (TREE_CODE (bsi_stmt (bsi)) != LABEL_EXPR)
3534 if (label_to_block (LABEL_EXPR_LABEL (bsi_stmt (bsi))) != bb)
3536 error ("Label %s to block does not match in bb %d\n",
3537 IDENTIFIER_POINTER (DECL_NAME (bsi_stmt (bsi))),
3542 if (decl_function_context (LABEL_EXPR_LABEL (bsi_stmt (bsi)))
3543 != current_function_decl)
3545 error ("Label %s has incorrect context in bb %d\n",
3546 IDENTIFIER_POINTER (DECL_NAME (bsi_stmt (bsi))),
3552 /* Verify that body of basic block BB is free of control flow. */
3553 for (; !bsi_end_p (bsi); bsi_next (&bsi))
3555 tree stmt = bsi_stmt (bsi);
3557 if (found_ctrl_stmt)
3559 error ("Control flow in the middle of basic block %d\n",
3564 if (stmt_ends_bb_p (stmt))
3565 found_ctrl_stmt = true;
3567 if (TREE_CODE (stmt) == LABEL_EXPR)
3569 error ("Label %s in the middle of basic block %d\n",
3570 IDENTIFIER_POINTER (DECL_NAME (stmt)),
3575 bsi = bsi_last (bb);
3576 if (bsi_end_p (bsi))
3579 stmt = bsi_stmt (bsi);
3581 if (is_ctrl_stmt (stmt))
3583 for (e = bb->succ; e; e = e->succ_next)
3584 if (e->flags & EDGE_FALLTHRU)
3586 error ("Fallthru edge after a control statement in bb %d \n",
3592 switch (TREE_CODE (stmt))
3598 if (TREE_CODE (COND_EXPR_THEN (stmt)) != GOTO_EXPR
3599 || TREE_CODE (COND_EXPR_ELSE (stmt)) != GOTO_EXPR)
3601 error ("Structured COND_EXPR at the end of bb %d\n", bb->index);
3605 extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
3607 if (!true_edge || !false_edge
3608 || !(true_edge->flags & EDGE_TRUE_VALUE)
3609 || !(false_edge->flags & EDGE_FALSE_VALUE)
3610 || (true_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL))
3611 || (false_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL))
3612 || bb->succ->succ_next->succ_next)
3614 error ("Wrong outgoing edge flags at end of bb %d\n",
3619 if (!has_label_p (true_edge->dest,
3620 GOTO_DESTINATION (COND_EXPR_THEN (stmt))))
3622 error ("`then' label does not match edge at end of bb %d\n",
3627 if (!has_label_p (false_edge->dest,
3628 GOTO_DESTINATION (COND_EXPR_ELSE (stmt))))
3630 error ("`else' label does not match edge at end of bb %d\n",
3638 if (simple_goto_p (stmt))
3640 error ("Explicit goto at end of bb %d\n", bb->index);
3645 /* FIXME. We should double check that the labels in the
3646 destination blocks have their address taken. */
3647 for (e = bb->succ; e; e = e->succ_next)
3648 if ((e->flags & (EDGE_FALLTHRU | EDGE_TRUE_VALUE
3649 | EDGE_FALSE_VALUE))
3650 || !(e->flags & EDGE_ABNORMAL))
3652 error ("Wrong outgoing edge flags at end of bb %d\n",
3660 if (!bb->succ || bb->succ->succ_next
3661 || (bb->succ->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL
3662 | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
3664 error ("Wrong outgoing edge flags at end of bb %d\n", bb->index);
3667 if (bb->succ->dest != EXIT_BLOCK_PTR)
3669 error ("Return edge does not point to exit in bb %d\n",
3682 vec = SWITCH_LABELS (stmt);
3683 n = TREE_VEC_LENGTH (vec);
3685 /* Mark all the destination basic blocks. */
3686 for (i = 0; i < n; ++i)
3688 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
3689 basic_block label_bb = label_to_block (lab);
3691 if (label_bb->aux && label_bb->aux != (void *)1)
3693 label_bb->aux = (void *)1;
3696 /* Verify that the case labels are sorted. */
3697 prev = TREE_VEC_ELT (vec, 0);
3698 for (i = 1; i < n - 1; ++i)
3700 tree c = TREE_VEC_ELT (vec, i);
3703 error ("Found default case not at end of case vector");
3707 if (! tree_int_cst_lt (CASE_LOW (prev), CASE_LOW (c)))
3709 error ("Case labels not sorted:\n ");
3710 print_generic_expr (stderr, prev, 0);
3711 fprintf (stderr," is greater than ");
3712 print_generic_expr (stderr, c, 0);
3713 fprintf (stderr," but comes before it.\n");
3718 if (CASE_LOW (TREE_VEC_ELT (vec, n - 1)))
3720 error ("No default case found at end of case vector");
3724 for (e = bb->succ; e; e = e->succ_next)
3728 error ("Extra outgoing edge %d->%d\n",
3729 bb->index, e->dest->index);
3732 e->dest->aux = (void *)2;
3733 if ((e->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL
3734 | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
3736 error ("Wrong outgoing edge flags at end of bb %d\n",
3742 /* Check that we have all of them. */
3743 for (i = 0; i < n; ++i)
3745 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
3746 basic_block label_bb = label_to_block (lab);
3748 if (label_bb->aux != (void *)2)
3750 error ("Missing edge %i->%i\n",
3751 bb->index, label_bb->index);
3756 for (e = bb->succ; e; e = e->succ_next)
3757 e->dest->aux = (void *)0;
3764 if (dom_computed[CDI_DOMINATORS] >= DOM_NO_FAST_QUERY)
3765 verify_dominators (CDI_DOMINATORS);
3771 /* Updates phi nodes after creating forwarder block joined
3772 by edge FALLTHRU. */
3775 tree_make_forwarder_block (edge fallthru)
3778 basic_block dummy, bb;
3779 tree phi, new_phi, var, prev, next;
3781 dummy = fallthru->src;
3782 bb = fallthru->dest;
3784 if (!bb->pred->pred_next)
3787 /* If we redirected a branch we must create new phi nodes at the
3789 for (phi = phi_nodes (dummy); phi; phi = PHI_CHAIN (phi))
3791 var = PHI_RESULT (phi);
3792 new_phi = create_phi_node (var, bb);
3793 SSA_NAME_DEF_STMT (var) = new_phi;
3794 SET_PHI_RESULT (phi, make_ssa_name (SSA_NAME_VAR (var), phi));
3795 add_phi_arg (&new_phi, PHI_RESULT (phi), fallthru);
3798 /* Ensure that the PHI node chain is in the same order. */
3800 for (phi = phi_nodes (bb); phi; phi = next)
3802 next = PHI_CHAIN (phi);
3803 PHI_CHAIN (phi) = prev;
3806 set_phi_nodes (bb, prev);
3808 /* Add the arguments we have stored on edges. */
3809 for (e = bb->pred; e; e = e->pred_next)
3814 for (phi = phi_nodes (bb), var = PENDING_STMT (e);
3816 phi = PHI_CHAIN (phi), var = TREE_CHAIN (var))
3817 add_phi_arg (&phi, TREE_VALUE (var), e);
3819 PENDING_STMT (e) = NULL;
3824 /* Return true if basic block BB does nothing except pass control
3825 flow to another block and that we can safely insert a label at
3826 the start of the successor block. */
3829 tree_forwarder_block_p (basic_block bb)
3831 block_stmt_iterator bsi;
3834 /* If we have already determined that this block is not forwardable,
3835 then no further checks are necessary. */
3836 if (! bb_ann (bb)->forwardable)
3839 /* BB must have a single outgoing normal edge. Otherwise it can not be
3840 a forwarder block. */
3842 || bb->succ->succ_next
3843 || bb->succ->dest == EXIT_BLOCK_PTR
3844 || (bb->succ->flags & EDGE_ABNORMAL)
3845 || bb == ENTRY_BLOCK_PTR)
3847 bb_ann (bb)->forwardable = 0;
3851 /* Successors of the entry block are not forwarders. */
3852 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
3855 bb_ann (bb)->forwardable = 0;
3859 /* BB can not have any PHI nodes. This could potentially be relaxed
3860 early in compilation if we re-rewrote the variables appearing in
3861 any PHI nodes in forwarder blocks. */
3864 bb_ann (bb)->forwardable = 0;
3868 /* Now walk through the statements. We can ignore labels, anything else
3869 means this is not a forwarder block. */
3870 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3872 tree stmt = bsi_stmt (bsi);
3874 switch (TREE_CODE (stmt))
3877 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)))
3882 bb_ann (bb)->forwardable = 0;
3891 /* Thread jumps over empty statements.
3893 This code should _not_ thread over obviously equivalent conditions
3894 as that requires nontrivial updates to the SSA graph. */
3899 edge e, next, last, old;
3900 basic_block bb, dest, tmp;
3903 bool retval = false;
3906 bb_ann (bb)->forwardable = 1;
3908 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb)
3910 /* Don't waste time on unreachable blocks. */
3914 /* Nor on forwarders. */
3915 if (tree_forwarder_block_p (bb))
3918 /* This block is now part of a forwarding path, mark it as not
3919 forwardable so that we can detect loops. This bit will be
3921 bb_ann (bb)->forwardable = 0;
3923 /* Examine each of our block's successors to see if it is
3925 for (e = bb->succ; e; e = next)
3927 next = e->succ_next;
3929 /* If the edge is abnormal or its destination is not
3930 forwardable, then there's nothing to do. */
3931 if ((e->flags & EDGE_ABNORMAL)
3932 || !tree_forwarder_block_p (e->dest))
3935 /* Now walk through as many forwarder block as possible to
3936 find the ultimate destination we want to thread our jump
3938 last = e->dest->succ;
3939 bb_ann (e->dest)->forwardable = 0;
3940 for (dest = e->dest->succ->dest;
3941 tree_forwarder_block_p (dest);
3943 dest = dest->succ->dest)
3945 /* An infinite loop detected. We redirect the edge anyway, so
3946 that the loop is shrunk into single basic block. */
3947 if (!bb_ann (dest)->forwardable)
3950 if (dest->succ->dest == EXIT_BLOCK_PTR)
3953 bb_ann (dest)->forwardable = 0;
3956 /* Reset the forwardable marks to 1. */
3959 tmp = tmp->succ->dest)
3960 bb_ann (tmp)->forwardable = 1;
3962 if (dest == e->dest)
3965 old = find_edge (bb, dest);
3968 /* If there already is an edge, check whether the values
3969 in phi nodes differ. */
3970 if (!phi_alternatives_equal (dest, last, old))
3972 /* The previous block is forwarder. Redirect our jump
3973 to that target instead since we know it has no PHI
3974 nodes that will need updating. */
3977 /* That might mean that no forwarding at all is possible. */
3978 if (dest == e->dest)
3981 old = find_edge (bb, dest);
3985 /* Perform the redirection. */
3987 e = redirect_edge_and_branch (e, dest);
3989 /* TODO -- updating dominators in this case is simple. */
3990 free_dominance_info (CDI_DOMINATORS);
3994 /* Update PHI nodes. We know that the new argument should
3995 have the same value as the argument associated with LAST.
3996 Otherwise we would have changed our target block above. */
3997 for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi))
3999 arg = phi_arg_from_edge (phi, last);
4002 add_phi_arg (&phi, PHI_ARG_DEF (phi, arg), e);
4007 /* Reset the forwardable bit on our block since it's no longer in
4008 a forwarding chain path. */
4009 bb_ann (bb)->forwardable = 1;
4016 /* Return a non-special label in the head of basic block BLOCK.
4017 Create one if it doesn't exist. */
4020 tree_block_label (basic_block bb)
4022 block_stmt_iterator i, s = bsi_start (bb);
4026 for (i = s; !bsi_end_p (i); first = false, bsi_next (&i))
4028 stmt = bsi_stmt (i);
4029 if (TREE_CODE (stmt) != LABEL_EXPR)
4031 label = LABEL_EXPR_LABEL (stmt);
4032 if (!DECL_NONLOCAL (label))
4035 bsi_move_before (&i, &s);
4040 label = create_artificial_label ();
4041 stmt = build1 (LABEL_EXPR, void_type_node, label);
4042 bsi_insert_before (&s, stmt, BSI_NEW_STMT);
4047 /* Attempt to perform edge redirection by replacing a possibly complex
4048 jump instruction by a goto or by removing the jump completely.
4049 This can apply only if all edges now point to the same block. The
4050 parameters and return values are equivalent to
4051 redirect_edge_and_branch. */
4054 tree_try_redirect_by_replacing_jump (edge e, basic_block target)
4056 basic_block src = e->src;
4058 block_stmt_iterator b;
4061 /* Verify that all targets will be TARGET. */
4062 for (tmp = src->succ; tmp; tmp = tmp->succ_next)
4063 if (tmp->dest != target && tmp != e)
4072 stmt = bsi_stmt (b);
4074 if (TREE_CODE (stmt) == COND_EXPR
4075 || TREE_CODE (stmt) == SWITCH_EXPR)
4078 e = ssa_redirect_edge (e, target);
4079 e->flags = EDGE_FALLTHRU;
4087 /* Redirect E to DEST. Return NULL on failure. Otherwise, return the
4088 edge representing the redirected branch. */
4091 tree_redirect_edge_and_branch (edge e, basic_block dest)
4093 basic_block bb = e->src;
4094 block_stmt_iterator bsi;
4098 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
4101 if (e->src != ENTRY_BLOCK_PTR
4102 && (ret = tree_try_redirect_by_replacing_jump (e, dest)))
4105 if (e->dest == dest)
4108 label = tree_block_label (dest);
4110 bsi = bsi_last (bb);
4111 stmt = bsi_end_p (bsi) ? NULL : bsi_stmt (bsi);
4113 switch (stmt ? TREE_CODE (stmt) : ERROR_MARK)
4116 stmt = (e->flags & EDGE_TRUE_VALUE
4117 ? COND_EXPR_THEN (stmt)
4118 : COND_EXPR_ELSE (stmt));
4119 GOTO_DESTINATION (stmt) = label;
4123 /* No non-abnormal edges should lead from a non-simple goto, and
4124 simple ones should be represented implicitly. */
4129 tree vec = SWITCH_LABELS (stmt);
4130 size_t i, n = TREE_VEC_LENGTH (vec);
4132 for (i = 0; i < n; ++i)
4134 tree elt = TREE_VEC_ELT (vec, i);
4135 if (label_to_block (CASE_LABEL (elt)) == e->dest)
4136 CASE_LABEL (elt) = label;
4143 e->flags |= EDGE_FALLTHRU;
4147 /* Otherwise it must be a fallthru edge, and we don't need to
4148 do anything besides redirecting it. */
4149 if (!(e->flags & EDGE_FALLTHRU))
4154 /* Update/insert PHI nodes as necessary. */
4156 /* Now update the edges in the CFG. */
4157 e = ssa_redirect_edge (e, dest);
4163 /* Simple wrapper, as we can always redirect fallthru edges. */
4166 tree_redirect_edge_and_branch_force (edge e, basic_block dest)
4168 e = tree_redirect_edge_and_branch (e, dest);
4176 /* Splits basic block BB after statement STMT (but at least after the
4177 labels). If STMT is NULL, BB is split just after the labels. */
4180 tree_split_block (basic_block bb, void *stmt)
4182 block_stmt_iterator bsi, bsi_tgt;
4187 new_bb = create_empty_bb (bb);
4189 /* Redirect the outgoing edges. */
4190 new_bb->succ = bb->succ;
4192 for (e = new_bb->succ; e; e = e->succ_next)
4195 if (stmt && TREE_CODE ((tree) stmt) == LABEL_EXPR)
4198 /* Move everything from BSI to the new basic block. */
4199 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4201 act = bsi_stmt (bsi);
4202 if (TREE_CODE (act) == LABEL_EXPR)
4215 bsi_tgt = bsi_start (new_bb);
4216 while (!bsi_end_p (bsi))
4218 act = bsi_stmt (bsi);
4220 bsi_insert_after (&bsi_tgt, act, BSI_NEW_STMT);
4227 /* Moves basic block BB after block AFTER. */
4230 tree_move_block_after (basic_block bb, basic_block after)
4232 if (bb->prev_bb == after)
4236 link_block (bb, after);
4242 /* Return true if basic_block can be duplicated. */
4245 tree_can_duplicate_bb_p (basic_block bb ATTRIBUTE_UNUSED)
4251 /* Create a duplicate of the basic block BB. NOTE: This does not
4252 preserve SSA form. */
4255 tree_duplicate_bb (basic_block bb)
4258 block_stmt_iterator bsi, bsi_tgt;
4260 new_bb = create_empty_bb (EXIT_BLOCK_PTR->prev_bb);
4261 bsi_tgt = bsi_start (new_bb);
4262 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4264 tree stmt = bsi_stmt (bsi);
4267 if (TREE_CODE (stmt) == LABEL_EXPR)
4270 copy = unshare_expr (stmt);
4272 /* Copy also the virtual operands. */
4273 get_stmt_ann (copy);
4274 copy_virtual_operands (copy, stmt);
4276 bsi_insert_after (&bsi_tgt, copy, BSI_NEW_STMT);
4283 /* Dump FUNCTION_DECL FN to file FILE using FLAGS (see TDF_* in tree.h) */
4286 dump_function_to_file (tree fn, FILE *file, int flags)
4288 tree arg, vars, var;
4289 bool ignore_topmost_bind = false, any_var = false;
4293 fprintf (file, "%s (", lang_hooks.decl_printable_name (fn, 2));
4295 arg = DECL_ARGUMENTS (fn);
4298 print_generic_expr (file, arg, dump_flags);
4299 if (TREE_CHAIN (arg))
4300 fprintf (file, ", ");
4301 arg = TREE_CHAIN (arg);
4303 fprintf (file, ")\n");
4305 if (flags & TDF_RAW)
4307 dump_node (fn, TDF_SLIM | flags, file);
4311 /* When GIMPLE is lowered, the variables are no longer available in
4312 BIND_EXPRs, so display them separately. */
4313 if (cfun && cfun->unexpanded_var_list)
4315 ignore_topmost_bind = true;
4317 fprintf (file, "{\n");
4318 for (vars = cfun->unexpanded_var_list; vars; vars = TREE_CHAIN (vars))
4320 var = TREE_VALUE (vars);
4322 print_generic_decl (file, var, flags);
4323 fprintf (file, "\n");
4329 if (basic_block_info)
4331 /* Make a CFG based dump. */
4332 if (!ignore_topmost_bind)
4333 fprintf (file, "{\n");
4335 if (any_var && n_basic_blocks)
4336 fprintf (file, "\n");
4339 dump_generic_bb (file, bb, 2, flags);
4341 fprintf (file, "}\n");
4347 /* Make a tree based dump. */
4348 chain = DECL_SAVED_TREE (fn);
4350 if (TREE_CODE (chain) == BIND_EXPR)
4352 if (ignore_topmost_bind)
4354 chain = BIND_EXPR_BODY (chain);
4362 if (!ignore_topmost_bind)
4363 fprintf (file, "{\n");
4368 fprintf (file, "\n");
4370 print_generic_stmt_indented (file, chain, flags, indent);
4371 if (ignore_topmost_bind)
4372 fprintf (file, "}\n");
4375 fprintf (file, "\n\n");
4379 /* Pretty print of the loops intermediate representation. */
4380 static void print_loop (FILE *, struct loop *, int);
4381 static void print_pred_bbs (FILE *, edge);
4382 static void print_succ_bbs (FILE *, edge);
4385 /* Print the predecessors indexes of edge E on FILE. */
4388 print_pred_bbs (FILE *file, edge e)
4393 else if (e->pred_next == NULL)
4394 fprintf (file, "bb_%d", e->src->index);
4398 fprintf (file, "bb_%d, ", e->src->index);
4399 print_pred_bbs (file, e->pred_next);
4404 /* Print the successors indexes of edge E on FILE. */
4407 print_succ_bbs (FILE *file, edge e)
4411 else if (e->succ_next == NULL)
4412 fprintf (file, "bb_%d", e->dest->index);
4415 fprintf (file, "bb_%d, ", e->dest->index);
4416 print_succ_bbs (file, e->succ_next);
4421 /* Pretty print LOOP on FILE, indented INDENT spaces. */
4424 print_loop (FILE *file, struct loop *loop, int indent)
4432 s_indent = (char *) alloca ((size_t) indent + 1);
4433 memset ((void *) s_indent, ' ', (size_t) indent);
4434 s_indent[indent] = '\0';
4436 /* Print the loop's header. */
4437 fprintf (file, "%sloop_%d\n", s_indent, loop->num);
4439 /* Print the loop's body. */
4440 fprintf (file, "%s{\n", s_indent);
4442 if (bb->loop_father == loop)
4444 /* Print the basic_block's header. */
4445 fprintf (file, "%s bb_%d (preds = {", s_indent, bb->index);
4446 print_pred_bbs (file, bb->pred);
4447 fprintf (file, "}, succs = {");
4448 print_succ_bbs (file, bb->succ);
4449 fprintf (file, "})\n");
4451 /* Print the basic_block's body. */
4452 fprintf (file, "%s {\n", s_indent);
4453 tree_dump_bb (bb, file, indent + 4);
4454 fprintf (file, "%s }\n", s_indent);
4457 print_loop (file, loop->inner, indent + 2);
4458 fprintf (file, "%s}\n", s_indent);
4459 print_loop (file, loop->next, indent);
4463 /* Follow a CFG edge from the entry point of the program, and on entry
4464 of a loop, pretty print the loop structure on FILE. */
4467 print_loop_ir (FILE *file)
4471 bb = BASIC_BLOCK (0);
4472 if (bb && bb->loop_father)
4473 print_loop (file, bb->loop_father, 0);
4477 /* Debugging loops structure at tree level. */
4480 debug_loop_ir (void)
4482 print_loop_ir (stderr);
4486 /* Return true if BB ends with a call, possibly followed by some
4487 instructions that must stay with the call. Return false,
4491 tree_block_ends_with_call_p (basic_block bb)
4493 block_stmt_iterator bsi = bsi_last (bb);
4494 return get_call_expr_in (bsi_stmt (bsi)) != NULL;
4498 /* Return true if BB ends with a conditional branch. Return false,
4502 tree_block_ends_with_condjump_p (basic_block bb)
4504 tree stmt = tsi_stmt (bsi_last (bb).tsi);
4505 return (TREE_CODE (stmt) == COND_EXPR);
4509 /* Return true if we need to add fake edge to exit at statement T.
4510 Helper function for tree_flow_call_edges_add. */
4513 need_fake_edge_p (tree t)
4517 /* NORETURN and LONGJMP calls already have an edge to exit.
4518 CONST, PURE and ALWAYS_RETURN calls do not need one.
4519 We don't currently check for CONST and PURE here, although
4520 it would be a good idea, because those attributes are
4521 figured out from the RTL in mark_constant_function, and
4522 the counter incrementation code from -fprofile-arcs
4523 leads to different results from -fbranch-probabilities. */
4524 call = get_call_expr_in (t);
4526 && !(call_expr_flags (call) &
4527 (ECF_NORETURN | ECF_LONGJMP | ECF_ALWAYS_RETURN)))
4530 if (TREE_CODE (t) == ASM_EXPR
4531 && (ASM_VOLATILE_P (t) || ASM_INPUT_P (t)))
4538 /* Add fake edges to the function exit for any non constant and non
4539 noreturn calls, volatile inline assembly in the bitmap of blocks
4540 specified by BLOCKS or to the whole CFG if BLOCKS is zero. Return
4541 the number of blocks that were split.
4543 The goal is to expose cases in which entering a basic block does
4544 not imply that all subsequent instructions must be executed. */
4547 tree_flow_call_edges_add (sbitmap blocks)
4550 int blocks_split = 0;
4551 int last_bb = last_basic_block;
4552 bool check_last_block = false;
4554 if (n_basic_blocks == 0)
4558 check_last_block = true;
4560 check_last_block = TEST_BIT (blocks, EXIT_BLOCK_PTR->prev_bb->index);
4562 /* In the last basic block, before epilogue generation, there will be
4563 a fallthru edge to EXIT. Special care is required if the last insn
4564 of the last basic block is a call because make_edge folds duplicate
4565 edges, which would result in the fallthru edge also being marked
4566 fake, which would result in the fallthru edge being removed by
4567 remove_fake_edges, which would result in an invalid CFG.
4569 Moreover, we can't elide the outgoing fake edge, since the block
4570 profiler needs to take this into account in order to solve the minimal
4571 spanning tree in the case that the call doesn't return.
4573 Handle this by adding a dummy instruction in a new last basic block. */
4574 if (check_last_block)
4576 basic_block bb = EXIT_BLOCK_PTR->prev_bb;
4577 block_stmt_iterator bsi = bsi_last (bb);
4579 if (!bsi_end_p (bsi))
4582 if (need_fake_edge_p (t))
4586 for (e = bb->succ; e; e = e->succ_next)
4587 if (e->dest == EXIT_BLOCK_PTR)
4589 bsi_insert_on_edge (e, build_empty_stmt ());
4590 bsi_commit_edge_inserts ((int *)NULL);
4596 /* Now add fake edges to the function exit for any non constant
4597 calls since there is no way that we can determine if they will
4599 for (i = 0; i < last_bb; i++)
4601 basic_block bb = BASIC_BLOCK (i);
4602 block_stmt_iterator bsi;
4603 tree stmt, last_stmt;
4608 if (blocks && !TEST_BIT (blocks, i))
4611 bsi = bsi_last (bb);
4612 if (!bsi_end_p (bsi))
4614 last_stmt = bsi_stmt (bsi);
4617 stmt = bsi_stmt (bsi);
4618 if (need_fake_edge_p (stmt))
4621 /* The handling above of the final block before the
4622 epilogue should be enough to verify that there is
4623 no edge to the exit block in CFG already.
4624 Calling make_edge in such case would cause us to
4625 mark that edge as fake and remove it later. */
4626 #ifdef ENABLE_CHECKING
4627 if (stmt == last_stmt)
4628 for (e = bb->succ; e; e = e->succ_next)
4629 if (e->dest == EXIT_BLOCK_PTR)
4633 /* Note that the following may create a new basic block
4634 and renumber the existing basic blocks. */
4635 if (stmt != last_stmt)
4637 e = split_block (bb, stmt);
4641 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
4645 while (!bsi_end_p (bsi));
4650 verify_flow_info ();
4652 return blocks_split;
4656 tree_purge_dead_eh_edges (basic_block bb)
4658 bool changed = false;
4660 tree stmt = last_stmt (bb);
4662 if (stmt && tree_can_throw_internal (stmt))
4665 for (e = bb->succ; e ; e = next)
4667 next = e->succ_next;
4668 if (e->flags & EDGE_EH)
4670 ssa_remove_edge (e);
4679 tree_purge_all_dead_eh_edges (bitmap blocks)
4681 bool changed = false;
4684 EXECUTE_IF_SET_IN_BITMAP (blocks, 0, i,
4685 { changed |= tree_purge_dead_eh_edges (BASIC_BLOCK (i)); });
4690 struct cfg_hooks tree_cfg_hooks = {
4692 tree_verify_flow_info,
4693 tree_dump_bb, /* dump_bb */
4694 create_bb, /* create_basic_block */
4695 tree_redirect_edge_and_branch,/* redirect_edge_and_branch */
4696 tree_redirect_edge_and_branch_force,/* redirect_edge_and_branch_force */
4697 remove_bb, /* delete_basic_block */
4698 tree_split_block, /* split_block */
4699 tree_move_block_after, /* move_block_after */
4700 tree_can_merge_blocks_p, /* can_merge_blocks_p */
4701 tree_merge_blocks, /* merge_blocks */
4702 tree_predict_edge, /* predict_edge */
4703 tree_predicted_by_p, /* predicted_by_p */
4704 tree_can_duplicate_bb_p, /* can_duplicate_block_p */
4705 tree_duplicate_bb, /* duplicate_block */
4706 tree_split_edge, /* split_edge */
4707 tree_make_forwarder_block, /* make_forward_block */
4708 NULL, /* tidy_fallthru_edge */
4709 tree_block_ends_with_call_p, /* block_ends_with_call_p */
4710 tree_block_ends_with_condjump_p, /* block_ends_with_condjump_p */
4711 tree_flow_call_edges_add /* flow_call_edges_add */
4715 /* Split all critical edges. */
4718 split_critical_edges (void)
4725 for (e = bb->succ; e ; e = e->succ_next)
4726 if (EDGE_CRITICAL_P (e) && !(e->flags & EDGE_ABNORMAL))
4733 struct tree_opt_pass pass_split_crit_edges =
4735 "crited", /* name */
4737 split_critical_edges, /* execute */
4740 0, /* static_pass_number */
4741 TV_TREE_SPLIT_EDGES, /* tv_id */
4742 PROP_cfg, /* properties required */
4743 PROP_no_crit_edges, /* properties_provided */
4744 0, /* properties_destroyed */
4745 0, /* todo_flags_start */
4746 TODO_dump_func, /* todo_flags_finish */
4749 /* Emit return warnings. */
4752 execute_warn_function_return (void)
4754 #ifdef USE_MAPPED_LOCATION
4755 source_location location;
4762 if (warn_missing_noreturn
4763 && !TREE_THIS_VOLATILE (cfun->decl)
4764 && EXIT_BLOCK_PTR->pred == NULL
4765 && !lang_hooks.function.missing_noreturn_ok_p (cfun->decl))
4766 warning ("%Jfunction might be possible candidate for attribute `noreturn'",
4769 /* If we have a path to EXIT, then we do return. */
4770 if (TREE_THIS_VOLATILE (cfun->decl)
4771 && EXIT_BLOCK_PTR->pred != NULL)
4773 #ifdef USE_MAPPED_LOCATION
4774 location = UNKNOWN_LOCATION;
4778 for (e = EXIT_BLOCK_PTR->pred; e ; e = e->pred_next)
4780 last = last_stmt (e->src);
4781 if (TREE_CODE (last) == RETURN_EXPR
4782 #ifdef USE_MAPPED_LOCATION
4783 && (location = EXPR_LOCATION (last)) != UNKNOWN_LOCATION)
4785 && (locus = EXPR_LOCUS (last)) != NULL)
4789 #ifdef USE_MAPPED_LOCATION
4790 if (location == UNKNOWN_LOCATION)
4791 location = cfun->function_end_locus;
4792 warning ("%H`noreturn' function does return", &location);
4795 locus = &cfun->function_end_locus;
4796 warning ("%H`noreturn' function does return", locus);
4800 /* If we see "return;" in some basic block, then we do reach the end
4801 without returning a value. */
4802 else if (warn_return_type
4803 && EXIT_BLOCK_PTR->pred != NULL
4804 && !VOID_TYPE_P (TREE_TYPE (TREE_TYPE (cfun->decl))))
4806 for (e = EXIT_BLOCK_PTR->pred; e ; e = e->pred_next)
4808 tree last = last_stmt (e->src);
4809 if (TREE_CODE (last) == RETURN_EXPR
4810 && TREE_OPERAND (last, 0) == NULL)
4812 #ifdef USE_MAPPED_LOCATION
4813 location = EXPR_LOCATION (last);
4814 if (location == UNKNOWN_LOCATION)
4815 location = cfun->function_end_locus;
4816 warning ("%Hcontrol reaches end of non-void function", &location);
4818 locus = EXPR_LOCUS (last);
4820 locus = &cfun->function_end_locus;
4821 warning ("%Hcontrol reaches end of non-void function", locus);
4830 /* Given a basic block B which ends with a conditional and has
4831 precisely two successors, determine which of the edges is taken if
4832 the conditional is true and which is taken if the conditional is
4833 false. Set TRUE_EDGE and FALSE_EDGE appropriately. */
4836 extract_true_false_edges_from_block (basic_block b,
4842 if (e->flags & EDGE_TRUE_VALUE)
4845 *false_edge = e->succ_next;
4850 *true_edge = e->succ_next;
4854 struct tree_opt_pass pass_warn_function_return =
4858 execute_warn_function_return, /* execute */
4861 0, /* static_pass_number */
4863 PROP_cfg, /* properties_required */
4864 0, /* properties_provided */
4865 0, /* properties_destroyed */
4866 0, /* todo_flags_start */
4867 0 /* todo_flags_finish */
4870 #include "gt-tree-cfg.h"