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);
77 static tree tree_block_label (basic_block bb);
80 static void make_edges (void);
81 static void make_ctrl_stmt_edges (basic_block);
82 static void make_exit_edges (basic_block);
83 static void make_cond_expr_edges (basic_block);
84 static void make_switch_expr_edges (basic_block);
85 static void make_goto_expr_edges (basic_block);
86 static edge tree_redirect_edge_and_branch (edge, basic_block);
87 static edge tree_try_redirect_by_replacing_jump (edge, basic_block);
88 static void split_critical_edges (void);
90 /* Various helpers. */
91 static inline bool stmt_starts_bb_p (tree, tree);
92 static int tree_verify_flow_info (void);
93 static void tree_make_forwarder_block (edge);
94 static bool thread_jumps (void);
95 static bool tree_forwarder_block_p (basic_block);
96 static void bsi_commit_edge_inserts_1 (edge e);
97 static void tree_cfg2vcg (FILE *);
99 /* Flowgraph optimization and cleanup. */
100 static void tree_merge_blocks (basic_block, basic_block);
101 static bool tree_can_merge_blocks_p (basic_block, basic_block);
102 static void remove_bb (basic_block);
103 static void group_case_labels (void);
104 static void cleanup_dead_labels (void);
105 static bool cleanup_control_flow (void);
106 static bool cleanup_control_expr_graph (basic_block, block_stmt_iterator);
107 static edge find_taken_edge_cond_expr (basic_block, tree);
108 static edge find_taken_edge_switch_expr (basic_block, tree);
109 static tree find_case_label_for_value (tree, tree);
110 static bool phi_alternatives_equal (basic_block, edge, edge);
113 /*---------------------------------------------------------------------------
115 ---------------------------------------------------------------------------*/
117 /* Entry point to the CFG builder for trees. TP points to the list of
118 statements to be added to the flowgraph. */
121 build_tree_cfg (tree *tp)
123 /* Register specific tree functions. */
124 tree_register_cfg_hooks ();
126 /* Initialize rbi_pool. */
129 /* Initialize the basic block array. */
132 last_basic_block = 0;
133 VARRAY_BB_INIT (basic_block_info, initial_cfg_capacity, "basic_block_info");
134 memset ((void *) &cfg_stats, 0, sizeof (cfg_stats));
136 /* Build a mapping of labels to their associated blocks. */
137 VARRAY_BB_INIT (label_to_block_map, initial_cfg_capacity,
138 "label to block map");
140 ENTRY_BLOCK_PTR->next_bb = EXIT_BLOCK_PTR;
141 EXIT_BLOCK_PTR->prev_bb = ENTRY_BLOCK_PTR;
143 found_computed_goto = 0;
146 /* Computed gotos are hell to deal with, especially if there are
147 lots of them with a large number of destinations. So we factor
148 them to a common computed goto location before we build the
149 edge list. After we convert back to normal form, we will un-factor
150 the computed gotos since factoring introduces an unwanted jump. */
151 if (found_computed_goto)
152 factor_computed_gotos ();
154 /* Make sure there is always at least one block, even if its empty. */
155 if (n_basic_blocks == 0)
156 create_empty_bb (ENTRY_BLOCK_PTR);
158 create_block_annotation (ENTRY_BLOCK_PTR);
159 create_block_annotation (EXIT_BLOCK_PTR);
161 /* Adjust the size of the array. */
162 VARRAY_GROW (basic_block_info, n_basic_blocks);
164 /* To speed up statement iterator walks, we first purge dead labels. */
165 cleanup_dead_labels ();
167 /* Group case nodes to reduce the number of edges.
168 We do this after cleaning up dead labels because otherwise we miss
169 a lot of obvious case merging opportunities. */
170 group_case_labels ();
172 /* Create the edges of the flowgraph. */
175 /* Debugging dumps. */
177 /* Write the flowgraph to a VCG file. */
179 int local_dump_flags;
180 FILE *dump_file = dump_begin (TDI_vcg, &local_dump_flags);
183 tree_cfg2vcg (dump_file);
184 dump_end (TDI_vcg, dump_file);
188 /* Dump a textual representation of the flowgraph. */
190 dump_tree_cfg (dump_file, dump_flags);
194 execute_build_cfg (void)
196 build_tree_cfg (&DECL_SAVED_TREE (current_function_decl));
199 struct tree_opt_pass pass_build_cfg =
203 execute_build_cfg, /* execute */
206 0, /* static_pass_number */
207 TV_TREE_CFG, /* tv_id */
208 PROP_gimple_leh, /* properties_required */
209 PROP_cfg, /* properties_provided */
210 0, /* properties_destroyed */
211 0, /* todo_flags_start */
212 TODO_verify_stmts /* todo_flags_finish */
215 /* Search the CFG for any computed gotos. If found, factor them to a
216 common computed goto site. Also record the location of that site so
217 that we can un-factor the gotos after we have converted back to
221 factor_computed_gotos (void)
224 tree factored_label_decl = NULL;
226 tree factored_computed_goto_label = NULL;
227 tree factored_computed_goto = NULL;
229 /* We know there are one or more computed gotos in this function.
230 Examine the last statement in each basic block to see if the block
231 ends with a computed goto. */
235 block_stmt_iterator bsi = bsi_last (bb);
240 last = bsi_stmt (bsi);
242 /* Ignore the computed goto we create when we factor the original
244 if (last == factored_computed_goto)
247 /* If the last statement is a computed goto, factor it. */
248 if (computed_goto_p (last))
252 /* The first time we find a computed goto we need to create
253 the factored goto block and the variable each original
254 computed goto will use for their goto destination. */
255 if (! factored_computed_goto)
257 basic_block new_bb = create_empty_bb (bb);
258 block_stmt_iterator new_bsi = bsi_start (new_bb);
260 /* Create the destination of the factored goto. Each original
261 computed goto will put its desired destination into this
262 variable and jump to the label we create immediately
264 var = create_tmp_var (ptr_type_node, "gotovar");
266 /* Build a label for the new block which will contain the
267 factored computed goto. */
268 factored_label_decl = create_artificial_label ();
269 factored_computed_goto_label
270 = build1 (LABEL_EXPR, void_type_node, factored_label_decl);
271 bsi_insert_after (&new_bsi, factored_computed_goto_label,
274 /* Build our new computed goto. */
275 factored_computed_goto = build1 (GOTO_EXPR, void_type_node, var);
276 bsi_insert_after (&new_bsi, factored_computed_goto,
280 /* Copy the original computed goto's destination into VAR. */
281 assignment = build (MODIFY_EXPR, ptr_type_node,
282 var, GOTO_DESTINATION (last));
283 bsi_insert_before (&bsi, assignment, BSI_SAME_STMT);
285 /* And re-vector the computed goto to the new destination. */
286 GOTO_DESTINATION (last) = factored_label_decl;
292 /* Create annotations for a single basic block. */
295 create_block_annotation (basic_block bb)
297 /* Verify that the tree_annotations field is clear. */
298 if (bb->tree_annotations)
300 bb->tree_annotations = ggc_alloc_cleared (sizeof (struct bb_ann_d));
304 /* Free the annotations for all the basic blocks. */
306 static void free_blocks_annotations (void)
308 clear_blocks_annotations ();
312 /* Clear the annotations for all the basic blocks. */
315 clear_blocks_annotations (void)
319 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb)
320 bb->tree_annotations = NULL;
324 /* Build a flowgraph for the statement_list STMT_LIST. */
327 make_blocks (tree stmt_list)
329 tree_stmt_iterator i = tsi_start (stmt_list);
331 bool start_new_block = true;
332 bool first_stmt_of_list = true;
333 basic_block bb = ENTRY_BLOCK_PTR;
335 while (!tsi_end_p (i))
342 /* If the statement starts a new basic block or if we have determined
343 in a previous pass that we need to create a new block for STMT, do
345 if (start_new_block || stmt_starts_bb_p (stmt, prev_stmt))
347 if (!first_stmt_of_list)
348 stmt_list = tsi_split_statement_list_before (&i);
349 bb = create_basic_block (stmt_list, NULL, bb);
350 start_new_block = false;
353 /* Now add STMT to BB and create the subgraphs for special statement
355 set_bb_for_stmt (stmt, bb);
357 if (computed_goto_p (stmt))
358 found_computed_goto = true;
360 /* If STMT is a basic block terminator, set START_NEW_BLOCK for the
362 if (stmt_ends_bb_p (stmt))
363 start_new_block = true;
366 first_stmt_of_list = false;
371 /* Create and return a new empty basic block after bb AFTER. */
374 create_bb (void *h, void *e, basic_block after)
381 /* Create and initialize a new basic block. */
383 memset (bb, 0, sizeof (*bb));
385 bb->index = last_basic_block;
387 bb->stmt_list = h ? h : alloc_stmt_list ();
389 /* Add the new block to the linked list of blocks. */
390 link_block (bb, after);
392 /* Grow the basic block array if needed. */
393 if ((size_t) last_basic_block == VARRAY_SIZE (basic_block_info))
395 size_t new_size = last_basic_block + (last_basic_block + 3) / 4;
396 VARRAY_GROW (basic_block_info, new_size);
399 /* Add the newly created block to the array. */
400 BASIC_BLOCK (last_basic_block) = bb;
402 create_block_annotation (bb);
407 initialize_bb_rbi (bb);
412 /*---------------------------------------------------------------------------
414 ---------------------------------------------------------------------------*/
416 /* Join all the blocks in the flowgraph. */
424 /* Create an edge from entry to the first block with executable
426 make_edge (ENTRY_BLOCK_PTR, BASIC_BLOCK (0), EDGE_FALLTHRU);
428 /* Traverse basic block array placing edges. */
431 tree first = first_stmt (bb);
432 tree last = last_stmt (bb);
436 /* Edges for statements that always alter flow control. */
437 if (is_ctrl_stmt (last))
438 make_ctrl_stmt_edges (bb);
440 /* Edges for statements that sometimes alter flow control. */
441 if (is_ctrl_altering_stmt (last))
442 make_exit_edges (bb);
445 /* Finally, if no edges were created above, this is a regular
446 basic block that only needs a fallthru edge. */
447 if (bb->succ == NULL)
448 make_edge (bb, bb->next_bb, EDGE_FALLTHRU);
451 /* If there is a fallthru edge to exit out of the last block, transform it
452 to a return statement. */
453 for (e = EXIT_BLOCK_PTR->prev_bb->succ; e; e = e->succ_next)
454 if (e->flags & EDGE_FALLTHRU)
457 if (e && e->dest == EXIT_BLOCK_PTR)
459 block_stmt_iterator bsi;
460 basic_block ret_bb = EXIT_BLOCK_PTR->prev_bb;
463 /* If E->SRC ends with a call that has an abnormal edge (for EH or
464 nonlocal goto), then we will need to split the edge to insert
465 an explicit return statement. */
466 if (e != ret_bb->succ || e->succ_next)
468 ret_bb = split_edge (e);
471 e->flags &= ~EDGE_FALLTHRU;
473 x = build (RETURN_EXPR, void_type_node, NULL_TREE);
474 bsi = bsi_last (ret_bb);
475 bsi_insert_after (&bsi, x, BSI_NEW_STMT);
478 /* We do not care about fake edges, so remove any that the CFG
479 builder inserted for completeness. */
480 remove_fake_edges ();
482 /* Clean up the graph and warn for unreachable code. */
487 /* Create edges for control statement at basic block BB. */
490 make_ctrl_stmt_edges (basic_block bb)
492 tree last = last_stmt (bb);
493 tree first = first_stmt (bb);
495 #if defined ENABLE_CHECKING
496 if (last == NULL_TREE)
500 if (TREE_CODE (first) == LABEL_EXPR
501 && DECL_NONLOCAL (LABEL_EXPR_LABEL (first)))
502 make_edge (ENTRY_BLOCK_PTR, bb, EDGE_ABNORMAL);
504 switch (TREE_CODE (last))
507 make_goto_expr_edges (bb);
511 make_edge (bb, EXIT_BLOCK_PTR, 0);
515 make_cond_expr_edges (bb);
519 make_switch_expr_edges (bb);
523 make_eh_edges (last);
524 /* Yet another NORETURN hack. */
525 if (bb->succ == NULL)
526 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
535 /* Create exit edges for statements in block BB that alter the flow of
536 control. Statements that alter the control flow are 'goto', 'return'
537 and calls to non-returning functions. */
540 make_exit_edges (basic_block bb)
542 tree last = last_stmt (bb);
544 if (last == NULL_TREE)
547 switch (TREE_CODE (last))
550 /* If this function receives a nonlocal goto, then we need to
551 make edges from this call site to all the nonlocal goto
553 if (TREE_SIDE_EFFECTS (last)
554 && current_function_has_nonlocal_label)
555 make_goto_expr_edges (bb);
557 /* If this statement has reachable exception handlers, then
558 create abnormal edges to them. */
559 make_eh_edges (last);
561 /* Some calls are known not to return. For such calls we create
564 We really need to revamp how we build edges so that it's not
565 such a bloody pain to avoid creating edges for this case since
566 all we do is remove these edges when we're done building the
568 if (call_expr_flags (last) & (ECF_NORETURN | ECF_LONGJMP))
570 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
574 /* Don't forget the fall-thru edge. */
575 make_edge (bb, bb->next_bb, EDGE_FALLTHRU);
579 /* A MODIFY_EXPR may have a CALL_EXPR on its RHS and the CALL_EXPR
580 may have an abnormal edge. Search the RHS for this case and
581 create any required edges. */
582 if (TREE_CODE (TREE_OPERAND (last, 1)) == CALL_EXPR
583 && TREE_SIDE_EFFECTS (TREE_OPERAND (last, 1))
584 && current_function_has_nonlocal_label)
585 make_goto_expr_edges (bb);
587 make_eh_edges (last);
588 make_edge (bb, bb->next_bb, EDGE_FALLTHRU);
597 /* Create the edges for a COND_EXPR starting at block BB.
598 At this point, both clauses must contain only simple gotos. */
601 make_cond_expr_edges (basic_block bb)
603 tree entry = last_stmt (bb);
604 basic_block then_bb, else_bb;
605 tree then_label, else_label;
607 #if defined ENABLE_CHECKING
608 if (entry == NULL_TREE || TREE_CODE (entry) != COND_EXPR)
612 /* Entry basic blocks for each component. */
613 then_label = GOTO_DESTINATION (COND_EXPR_THEN (entry));
614 else_label = GOTO_DESTINATION (COND_EXPR_ELSE (entry));
615 then_bb = label_to_block (then_label);
616 else_bb = label_to_block (else_label);
618 make_edge (bb, then_bb, EDGE_TRUE_VALUE);
619 make_edge (bb, else_bb, EDGE_FALSE_VALUE);
623 /* Create the edges for a SWITCH_EXPR starting at block BB.
624 At this point, the switch body has been lowered and the
625 SWITCH_LABELS filled in, so this is in effect a multi-way branch. */
628 make_switch_expr_edges (basic_block bb)
630 tree entry = last_stmt (bb);
634 vec = SWITCH_LABELS (entry);
635 n = TREE_VEC_LENGTH (vec);
637 for (i = 0; i < n; ++i)
639 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
640 basic_block label_bb = label_to_block (lab);
641 make_edge (bb, label_bb, 0);
646 /* Return the basic block holding label DEST. */
649 label_to_block (tree dest)
651 return VARRAY_BB (label_to_block_map, LABEL_DECL_UID (dest));
655 /* Create edges for a goto statement at block BB. */
658 make_goto_expr_edges (basic_block bb)
661 basic_block target_bb;
663 block_stmt_iterator last = bsi_last (bb);
665 goto_t = bsi_stmt (last);
667 /* If the last statement is not a GOTO (i.e., it is a RETURN_EXPR,
668 CALL_EXPR or MODIFY_EXPR), then the edge is an abnormal edge resulting
669 from a nonlocal goto. */
670 if (TREE_CODE (goto_t) != GOTO_EXPR)
672 dest = error_mark_node;
677 dest = GOTO_DESTINATION (goto_t);
680 /* A GOTO to a local label creates normal edges. */
681 if (simple_goto_p (goto_t))
683 edge e = make_edge (bb, label_to_block (dest), EDGE_FALLTHRU);
684 e->goto_locus = EXPR_LOCUS (goto_t);
689 /* Nothing more to do for nonlocal gotos. */
690 if (TREE_CODE (dest) == LABEL_DECL)
693 /* Computed gotos remain. */
696 /* Look for the block starting with the destination label. In the
697 case of a computed goto, make an edge to any label block we find
699 FOR_EACH_BB (target_bb)
701 block_stmt_iterator bsi;
703 for (bsi = bsi_start (target_bb); !bsi_end_p (bsi); bsi_next (&bsi))
705 tree target = bsi_stmt (bsi);
707 if (TREE_CODE (target) != LABEL_EXPR)
711 /* Computed GOTOs. Make an edge to every label block that has
712 been marked as a potential target for a computed goto. */
713 (FORCED_LABEL (LABEL_EXPR_LABEL (target)) && for_call == 0)
714 /* Nonlocal GOTO target. Make an edge to every label block
715 that has been marked as a potential target for a nonlocal
717 || (DECL_NONLOCAL (LABEL_EXPR_LABEL (target)) && for_call == 1))
719 make_edge (bb, target_bb, EDGE_ABNORMAL);
725 /* Degenerate case of computed goto with no labels. */
726 if (!for_call && !bb->succ)
727 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
731 /*---------------------------------------------------------------------------
733 ---------------------------------------------------------------------------*/
735 /* Remove unreachable blocks and other miscellaneous clean up work. */
738 cleanup_tree_cfg (void)
740 bool something_changed = true;
742 timevar_push (TV_TREE_CLEANUP_CFG);
744 /* These three transformations can cascade, so we iterate on them until
746 while (something_changed)
748 something_changed = cleanup_control_flow ();
749 something_changed |= thread_jumps ();
750 something_changed |= delete_unreachable_blocks ();
753 /* Merging the blocks creates no new opportunities for the other
754 optimizations, so do it here. */
759 #ifdef ENABLE_CHECKING
762 timevar_pop (TV_TREE_CLEANUP_CFG);
766 /* Cleanup useless labels in basic blocks. This is something we wish
767 to do early because it allows us to group case labels before creating
768 the edges for the CFG, and it speeds up block statement iterators in
770 We only run this pass once, running it more than once is probably not
773 /* A map from basic block index to the leading label of that block. */
774 static tree *label_for_bb;
776 /* Callback for for_each_eh_region. Helper for cleanup_dead_labels. */
778 update_eh_label (struct eh_region *region)
780 tree old_label = get_eh_region_tree_label (region);
783 tree new_label = label_for_bb[label_to_block (old_label)->index];
784 set_eh_region_tree_label (region, new_label);
788 /* Cleanup redundant labels. This is a three-steo process:
789 1) Find the leading label for each block.
790 2) Redirect all references to labels to the leading labels.
791 3) Cleanup all useless labels. */
794 cleanup_dead_labels (void)
797 label_for_bb = xcalloc (last_basic_block, sizeof (tree));
799 /* Find a suitable label for each block. We use the first user-defined
800 label is there is one, or otherwise just the first label we see. */
803 block_stmt_iterator i;
805 for (i = bsi_start (bb); !bsi_end_p (i); bsi_next (&i))
807 tree label, stmt = bsi_stmt (i);
809 if (TREE_CODE (stmt) != LABEL_EXPR)
812 label = LABEL_EXPR_LABEL (stmt);
814 /* If we have not yet seen a label for the current block,
815 remember this one and see if there are more labels. */
816 if (! label_for_bb[bb->index])
818 label_for_bb[bb->index] = label;
822 /* If we did see a label for the current block already, but it
823 is an artificially created label, replace it if the current
824 label is a user defined label. */
825 if (! DECL_ARTIFICIAL (label)
826 && DECL_ARTIFICIAL (label_for_bb[bb->index]))
828 label_for_bb[bb->index] = label;
834 /* Now redirect all jumps/branches to the selected label.
835 First do so for each block ending in a control statement. */
838 tree stmt = last_stmt (bb);
842 switch (TREE_CODE (stmt))
846 tree true_branch, false_branch;
847 basic_block true_bb, false_bb;
849 true_branch = COND_EXPR_THEN (stmt);
850 false_branch = COND_EXPR_ELSE (stmt);
851 true_bb = label_to_block (GOTO_DESTINATION (true_branch));
852 false_bb = label_to_block (GOTO_DESTINATION (false_branch));
854 GOTO_DESTINATION (true_branch) = label_for_bb[true_bb->index];
855 GOTO_DESTINATION (false_branch) = label_for_bb[false_bb->index];
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)
869 tree label = CASE_LABEL (TREE_VEC_ELT (vec, i));
871 CASE_LABEL (TREE_VEC_ELT (vec, i)) =
872 label_for_bb[label_to_block (label)->index];
878 /* We have to handle GOTO_EXPRs until they're removed, and we don't
879 remove them until after we've created the CFG edges. */
882 tree label = GOTO_DESTINATION (stmt);
883 if (! computed_goto_p (stmt))
884 GOTO_DESTINATION (stmt) =
885 label_for_bb[label_to_block (label)->index];
894 for_each_eh_region (update_eh_label);
896 /* Finally, purge dead labels. All user-defined labels and labels that
897 can be the target of non-local gotos are preserved. */
900 block_stmt_iterator i;
901 tree label_for_this_bb = label_for_bb[bb->index];
903 if (! label_for_this_bb)
906 for (i = bsi_start (bb); !bsi_end_p (i); )
908 tree label, stmt = bsi_stmt (i);
910 if (TREE_CODE (stmt) != LABEL_EXPR)
913 label = LABEL_EXPR_LABEL (stmt);
915 if (label == label_for_this_bb
916 || ! DECL_ARTIFICIAL (label)
917 || DECL_NONLOCAL (label))
927 /* Look for blocks ending in a multiway branch (a SWITCH_EXPR in GIMPLE),
928 and scan the sorted vector of cases. Combine the ones jumping to the
930 Eg. three separate entries 1: 2: 3: become one entry 1..3: */
933 group_case_labels (void)
939 tree stmt = last_stmt (bb);
940 if (stmt && TREE_CODE (stmt) == SWITCH_EXPR)
942 tree labels = SWITCH_LABELS (stmt);
943 int old_size = TREE_VEC_LENGTH (labels);
944 int i, j, new_size = old_size;
946 /* Look for possible opportunities to merge cases.
947 Ignore the last element of the label vector because it
948 must be the default case. */
950 while (i < old_size - 2)
952 tree base_case, base_label, base_high, type;
953 base_case = TREE_VEC_ELT (labels, i);
958 type = TREE_TYPE (CASE_LOW (base_case));
959 base_label = CASE_LABEL (base_case);
960 base_high = CASE_HIGH (base_case) ?
961 CASE_HIGH (base_case) : CASE_LOW (base_case);
963 /* Try to merge case labels. Break out when we reach the end
964 of the label vector or when we cannot merge the next case
965 label with the current one. */
966 while (i < old_size - 2)
968 tree merge_case = TREE_VEC_ELT (labels, ++i);
969 tree merge_label = CASE_LABEL (merge_case);
970 tree t = int_const_binop (PLUS_EXPR, base_high,
971 integer_one_node, 1);
973 /* Merge the cases if they jump to the same place,
974 and their ranges are consecutive. */
975 if (merge_label == base_label
976 && tree_int_cst_equal (CASE_LOW (merge_case), t))
978 base_high = CASE_HIGH (merge_case) ?
979 CASE_HIGH (merge_case) : CASE_LOW (merge_case);
980 CASE_HIGH (base_case) = base_high;
981 TREE_VEC_ELT (labels, i) = NULL_TREE;
989 /* Compress the case labels in the label vector, and adjust the
990 length of the vector. */
991 for (i = 0, j = 0; i < new_size; i++)
993 while (! TREE_VEC_ELT (labels, j))
995 TREE_VEC_ELT (labels, i) = TREE_VEC_ELT (labels, j++);
997 TREE_VEC_LENGTH (labels) = new_size;
1002 /* Checks whether we can merge block B into block A. */
1005 tree_can_merge_blocks_p (basic_block a, basic_block b)
1008 block_stmt_iterator bsi;
1011 || a->succ->succ_next)
1014 if (a->succ->flags & EDGE_ABNORMAL)
1017 if (a->succ->dest != b)
1020 if (b == EXIT_BLOCK_PTR)
1023 if (b->pred->pred_next)
1026 /* If A ends by a statement causing exceptions or something similar, we
1027 cannot merge the blocks. */
1028 stmt = last_stmt (a);
1029 if (stmt && stmt_ends_bb_p (stmt))
1032 /* Do not allow a block with only a non-local label to be merged. */
1033 if (stmt && TREE_CODE (stmt) == LABEL_EXPR
1034 && DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)))
1037 /* There may be no phi nodes at the start of b. Most of these degenerate
1038 phi nodes should be cleaned up by kill_redundant_phi_nodes. */
1042 /* Do not remove user labels. */
1043 for (bsi = bsi_start (b); !bsi_end_p (bsi); bsi_next (&bsi))
1045 stmt = bsi_stmt (bsi);
1046 if (TREE_CODE (stmt) != LABEL_EXPR)
1048 if (!DECL_ARTIFICIAL (LABEL_EXPR_LABEL (stmt)))
1056 /* Merge block B into block A. */
1059 tree_merge_blocks (basic_block a, basic_block b)
1061 block_stmt_iterator bsi;
1062 tree_stmt_iterator last;
1065 fprintf (dump_file, "Merging blocks %d and %d\n", a->index, b->index);
1067 /* Ensure that B follows A. */
1068 move_block_after (b, a);
1070 if (!(a->succ->flags & EDGE_FALLTHRU))
1074 && stmt_ends_bb_p (last_stmt (a)))
1077 /* Remove labels from B and set bb_for_stmt to A for other statements. */
1078 for (bsi = bsi_start (b); !bsi_end_p (bsi);)
1080 if (TREE_CODE (bsi_stmt (bsi)) == LABEL_EXPR)
1084 set_bb_for_stmt (bsi_stmt (bsi), a);
1089 /* Merge the chains. */
1090 last = tsi_last (a->stmt_list);
1091 tsi_link_after (&last, b->stmt_list, TSI_NEW_STMT);
1092 b->stmt_list = NULL;
1096 /* Walk the function tree removing unnecessary statements.
1098 * Empty statement nodes are removed
1100 * Unnecessary TRY_FINALLY and TRY_CATCH blocks are removed
1102 * Unnecessary COND_EXPRs are removed
1104 * Some unnecessary BIND_EXPRs are removed
1106 Clearly more work could be done. The trick is doing the analysis
1107 and removal fast enough to be a net improvement in compile times.
1109 Note that when we remove a control structure such as a COND_EXPR
1110 BIND_EXPR, or TRY block, we will need to repeat this optimization pass
1111 to ensure we eliminate all the useless code. */
1122 static void remove_useless_stmts_1 (tree *, struct rus_data *);
1125 remove_useless_stmts_warn_notreached (tree stmt)
1127 if (EXPR_LOCUS (stmt))
1129 warning ("%Hwill never be executed", EXPR_LOCUS (stmt));
1133 switch (TREE_CODE (stmt))
1135 case STATEMENT_LIST:
1137 tree_stmt_iterator i;
1138 for (i = tsi_start (stmt); !tsi_end_p (i); tsi_next (&i))
1139 if (remove_useless_stmts_warn_notreached (tsi_stmt (i)))
1145 if (remove_useless_stmts_warn_notreached (COND_EXPR_COND (stmt)))
1147 if (remove_useless_stmts_warn_notreached (COND_EXPR_THEN (stmt)))
1149 if (remove_useless_stmts_warn_notreached (COND_EXPR_ELSE (stmt)))
1153 case TRY_FINALLY_EXPR:
1154 case TRY_CATCH_EXPR:
1155 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt, 0)))
1157 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt, 1)))
1162 return remove_useless_stmts_warn_notreached (CATCH_BODY (stmt));
1163 case EH_FILTER_EXPR:
1164 return remove_useless_stmts_warn_notreached (EH_FILTER_FAILURE (stmt));
1166 return remove_useless_stmts_warn_notreached (BIND_EXPR_BLOCK (stmt));
1169 /* Not a live container. */
1177 remove_useless_stmts_cond (tree *stmt_p, struct rus_data *data)
1179 tree then_clause, else_clause, cond;
1180 bool save_has_label, then_has_label, else_has_label;
1182 save_has_label = data->has_label;
1183 data->has_label = false;
1184 data->last_goto = NULL;
1186 remove_useless_stmts_1 (&COND_EXPR_THEN (*stmt_p), data);
1188 then_has_label = data->has_label;
1189 data->has_label = false;
1190 data->last_goto = NULL;
1192 remove_useless_stmts_1 (&COND_EXPR_ELSE (*stmt_p), data);
1194 else_has_label = data->has_label;
1195 data->has_label = save_has_label | then_has_label | else_has_label;
1198 then_clause = COND_EXPR_THEN (*stmt_p);
1199 else_clause = COND_EXPR_ELSE (*stmt_p);
1200 cond = COND_EXPR_COND (*stmt_p);
1202 /* If neither arm does anything at all, we can remove the whole IF. */
1203 if (!TREE_SIDE_EFFECTS (then_clause) && !TREE_SIDE_EFFECTS (else_clause))
1205 *stmt_p = build_empty_stmt ();
1206 data->repeat = true;
1209 /* If there are no reachable statements in an arm, then we can
1210 zap the entire conditional. */
1211 else if (integer_nonzerop (cond) && !else_has_label)
1213 if (warn_notreached)
1214 remove_useless_stmts_warn_notreached (else_clause);
1215 *stmt_p = then_clause;
1216 data->repeat = true;
1218 else if (integer_zerop (cond) && !then_has_label)
1220 if (warn_notreached)
1221 remove_useless_stmts_warn_notreached (then_clause);
1222 *stmt_p = else_clause;
1223 data->repeat = true;
1226 /* Check a couple of simple things on then/else with single stmts. */
1229 tree then_stmt = expr_only (then_clause);
1230 tree else_stmt = expr_only (else_clause);
1232 /* Notice branches to a common destination. */
1233 if (then_stmt && else_stmt
1234 && TREE_CODE (then_stmt) == GOTO_EXPR
1235 && TREE_CODE (else_stmt) == GOTO_EXPR
1236 && (GOTO_DESTINATION (then_stmt) == GOTO_DESTINATION (else_stmt)))
1238 *stmt_p = then_stmt;
1239 data->repeat = true;
1242 /* If the THEN/ELSE clause merely assigns a value to a variable or
1243 parameter which is already known to contain that value, then
1244 remove the useless THEN/ELSE clause. */
1245 else if (TREE_CODE (cond) == VAR_DECL || TREE_CODE (cond) == PARM_DECL)
1248 && TREE_CODE (else_stmt) == MODIFY_EXPR
1249 && TREE_OPERAND (else_stmt, 0) == cond
1250 && integer_zerop (TREE_OPERAND (else_stmt, 1)))
1251 COND_EXPR_ELSE (*stmt_p) = alloc_stmt_list ();
1253 else if ((TREE_CODE (cond) == EQ_EXPR || TREE_CODE (cond) == NE_EXPR)
1254 && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL
1255 || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL)
1256 && TREE_CONSTANT (TREE_OPERAND (cond, 1)))
1258 tree stmt = (TREE_CODE (cond) == EQ_EXPR
1259 ? then_stmt : else_stmt);
1260 tree *location = (TREE_CODE (cond) == EQ_EXPR
1261 ? &COND_EXPR_THEN (*stmt_p)
1262 : &COND_EXPR_ELSE (*stmt_p));
1265 && TREE_CODE (stmt) == MODIFY_EXPR
1266 && TREE_OPERAND (stmt, 0) == TREE_OPERAND (cond, 0)
1267 && TREE_OPERAND (stmt, 1) == TREE_OPERAND (cond, 1))
1268 *location = alloc_stmt_list ();
1272 /* Protect GOTOs in the arm of COND_EXPRs from being removed. They
1273 would be re-introduced during lowering. */
1274 data->last_goto = NULL;
1279 remove_useless_stmts_tf (tree *stmt_p, struct rus_data *data)
1281 bool save_may_branch, save_may_throw;
1282 bool this_may_branch, this_may_throw;
1284 /* Collect may_branch and may_throw information for the body only. */
1285 save_may_branch = data->may_branch;
1286 save_may_throw = data->may_throw;
1287 data->may_branch = false;
1288 data->may_throw = false;
1289 data->last_goto = NULL;
1291 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 0), data);
1293 this_may_branch = data->may_branch;
1294 this_may_throw = data->may_throw;
1295 data->may_branch |= save_may_branch;
1296 data->may_throw |= save_may_throw;
1297 data->last_goto = NULL;
1299 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 1), data);
1301 /* If the body is empty, then we can emit the FINALLY block without
1302 the enclosing TRY_FINALLY_EXPR. */
1303 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 0)))
1305 *stmt_p = TREE_OPERAND (*stmt_p, 1);
1306 data->repeat = true;
1309 /* If the handler is empty, then we can emit the TRY block without
1310 the enclosing TRY_FINALLY_EXPR. */
1311 else if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 1)))
1313 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1314 data->repeat = true;
1317 /* If the body neither throws, nor branches, then we can safely
1318 string the TRY and FINALLY blocks together. */
1319 else if (!this_may_branch && !this_may_throw)
1321 tree stmt = *stmt_p;
1322 *stmt_p = TREE_OPERAND (stmt, 0);
1323 append_to_statement_list (TREE_OPERAND (stmt, 1), stmt_p);
1324 data->repeat = true;
1330 remove_useless_stmts_tc (tree *stmt_p, struct rus_data *data)
1332 bool save_may_throw, this_may_throw;
1333 tree_stmt_iterator i;
1336 /* Collect may_throw information for the body only. */
1337 save_may_throw = data->may_throw;
1338 data->may_throw = false;
1339 data->last_goto = NULL;
1341 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 0), data);
1343 this_may_throw = data->may_throw;
1344 data->may_throw = save_may_throw;
1346 /* If the body cannot throw, then we can drop the entire TRY_CATCH_EXPR. */
1347 if (!this_may_throw)
1349 if (warn_notreached)
1350 remove_useless_stmts_warn_notreached (TREE_OPERAND (*stmt_p, 1));
1351 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1352 data->repeat = true;
1356 /* Process the catch clause specially. We may be able to tell that
1357 no exceptions propagate past this point. */
1359 this_may_throw = true;
1360 i = tsi_start (TREE_OPERAND (*stmt_p, 1));
1361 stmt = tsi_stmt (i);
1362 data->last_goto = NULL;
1364 switch (TREE_CODE (stmt))
1367 for (; !tsi_end_p (i); tsi_next (&i))
1369 stmt = tsi_stmt (i);
1370 /* If we catch all exceptions, then the body does not
1371 propagate exceptions past this point. */
1372 if (CATCH_TYPES (stmt) == NULL)
1373 this_may_throw = false;
1374 data->last_goto = NULL;
1375 remove_useless_stmts_1 (&CATCH_BODY (stmt), data);
1379 case EH_FILTER_EXPR:
1380 if (EH_FILTER_MUST_NOT_THROW (stmt))
1381 this_may_throw = false;
1382 else if (EH_FILTER_TYPES (stmt) == NULL)
1383 this_may_throw = false;
1384 remove_useless_stmts_1 (&EH_FILTER_FAILURE (stmt), data);
1388 /* Otherwise this is a cleanup. */
1389 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 1), data);
1391 /* If the cleanup is empty, then we can emit the TRY block without
1392 the enclosing TRY_CATCH_EXPR. */
1393 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 1)))
1395 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1396 data->repeat = true;
1400 data->may_throw |= this_may_throw;
1405 remove_useless_stmts_bind (tree *stmt_p, struct rus_data *data)
1409 /* First remove anything underneath the BIND_EXPR. */
1410 remove_useless_stmts_1 (&BIND_EXPR_BODY (*stmt_p), data);
1412 /* If the BIND_EXPR has no variables, then we can pull everything
1413 up one level and remove the BIND_EXPR, unless this is the toplevel
1414 BIND_EXPR for the current function or an inlined function.
1416 When this situation occurs we will want to apply this
1417 optimization again. */
1418 block = BIND_EXPR_BLOCK (*stmt_p);
1419 if (BIND_EXPR_VARS (*stmt_p) == NULL_TREE
1420 && *stmt_p != DECL_SAVED_TREE (current_function_decl)
1422 || ! BLOCK_ABSTRACT_ORIGIN (block)
1423 || (TREE_CODE (BLOCK_ABSTRACT_ORIGIN (block))
1426 *stmt_p = BIND_EXPR_BODY (*stmt_p);
1427 data->repeat = true;
1433 remove_useless_stmts_goto (tree *stmt_p, struct rus_data *data)
1435 tree dest = GOTO_DESTINATION (*stmt_p);
1437 data->may_branch = true;
1438 data->last_goto = NULL;
1440 /* Record the last goto expr, so that we can delete it if unnecessary. */
1441 if (TREE_CODE (dest) == LABEL_DECL)
1442 data->last_goto = stmt_p;
1447 remove_useless_stmts_label (tree *stmt_p, struct rus_data *data)
1449 tree label = LABEL_EXPR_LABEL (*stmt_p);
1451 data->has_label = true;
1453 /* We do want to jump across non-local label receiver code. */
1454 if (DECL_NONLOCAL (label))
1455 data->last_goto = NULL;
1457 else if (data->last_goto && GOTO_DESTINATION (*data->last_goto) == label)
1459 *data->last_goto = build_empty_stmt ();
1460 data->repeat = true;
1463 /* ??? Add something here to delete unused labels. */
1467 /* If the function is "const" or "pure", then clear TREE_SIDE_EFFECTS on its
1468 decl. This allows us to eliminate redundant or useless
1469 calls to "const" functions.
1471 Gimplifier already does the same operation, but we may notice functions
1472 being const and pure once their calls has been gimplified, so we need
1473 to update the flag. */
1476 update_call_expr_flags (tree call)
1478 tree decl = get_callee_fndecl (call);
1481 if (call_expr_flags (call) & (ECF_CONST | ECF_PURE))
1482 TREE_SIDE_EFFECTS (call) = 0;
1483 if (TREE_NOTHROW (decl))
1484 TREE_NOTHROW (call) = 1;
1488 /* T is CALL_EXPR. Set current_function_calls_* flags. */
1491 notice_special_calls (tree t)
1493 int flags = call_expr_flags (t);
1495 if (flags & ECF_MAY_BE_ALLOCA)
1496 current_function_calls_alloca = true;
1497 if (flags & ECF_RETURNS_TWICE)
1498 current_function_calls_setjmp = true;
1502 /* Clear flags set by notice_special_calls. Used by dead code removal
1503 to update the flags. */
1506 clear_special_calls (void)
1508 current_function_calls_alloca = false;
1509 current_function_calls_setjmp = false;
1514 remove_useless_stmts_1 (tree *tp, struct rus_data *data)
1518 switch (TREE_CODE (t))
1521 remove_useless_stmts_cond (tp, data);
1524 case TRY_FINALLY_EXPR:
1525 remove_useless_stmts_tf (tp, data);
1528 case TRY_CATCH_EXPR:
1529 remove_useless_stmts_tc (tp, data);
1533 remove_useless_stmts_bind (tp, data);
1537 remove_useless_stmts_goto (tp, data);
1541 remove_useless_stmts_label (tp, data);
1546 data->last_goto = NULL;
1547 data->may_branch = true;
1552 data->last_goto = NULL;
1553 notice_special_calls (t);
1554 update_call_expr_flags (t);
1555 if (tree_could_throw_p (t))
1556 data->may_throw = true;
1560 data->last_goto = NULL;
1562 if (TREE_CODE (TREE_OPERAND (t, 1)) == CALL_EXPR)
1564 update_call_expr_flags (TREE_OPERAND (t, 1));
1565 notice_special_calls (TREE_OPERAND (t, 1));
1567 if (tree_could_throw_p (t))
1568 data->may_throw = true;
1571 case STATEMENT_LIST:
1573 tree_stmt_iterator i = tsi_start (t);
1574 while (!tsi_end_p (i))
1577 if (IS_EMPTY_STMT (t))
1583 remove_useless_stmts_1 (tsi_stmt_ptr (i), data);
1586 if (TREE_CODE (t) == STATEMENT_LIST)
1588 tsi_link_before (&i, t, TSI_SAME_STMT);
1598 data->last_goto = NULL;
1602 data->last_goto = NULL;
1608 remove_useless_stmts (void)
1610 struct rus_data data;
1612 clear_special_calls ();
1616 memset (&data, 0, sizeof (data));
1617 remove_useless_stmts_1 (&DECL_SAVED_TREE (current_function_decl), &data);
1619 while (data.repeat);
1623 struct tree_opt_pass pass_remove_useless_stmts =
1625 "useless", /* name */
1627 remove_useless_stmts, /* execute */
1630 0, /* static_pass_number */
1632 PROP_gimple_any, /* properties_required */
1633 0, /* properties_provided */
1634 0, /* properties_destroyed */
1635 0, /* todo_flags_start */
1636 TODO_dump_func /* todo_flags_finish */
1640 /* Remove obviously useless statements in basic block BB. */
1643 cfg_remove_useless_stmts_bb (basic_block bb)
1645 block_stmt_iterator bsi;
1646 tree stmt = NULL_TREE;
1647 tree cond, var = NULL_TREE, val = NULL_TREE;
1648 struct var_ann_d *ann;
1650 /* Check whether we come here from a condition, and if so, get the
1653 || bb->pred->pred_next
1654 || !(bb->pred->flags & (EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
1657 cond = COND_EXPR_COND (last_stmt (bb->pred->src));
1659 if (TREE_CODE (cond) == VAR_DECL || TREE_CODE (cond) == PARM_DECL)
1662 val = (bb->pred->flags & EDGE_FALSE_VALUE
1663 ? boolean_false_node : boolean_true_node);
1665 else if (TREE_CODE (cond) == TRUTH_NOT_EXPR
1666 && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL
1667 || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL))
1669 var = TREE_OPERAND (cond, 0);
1670 val = (bb->pred->flags & EDGE_FALSE_VALUE
1671 ? boolean_true_node : boolean_false_node);
1675 if (bb->pred->flags & EDGE_FALSE_VALUE)
1676 cond = invert_truthvalue (cond);
1677 if (TREE_CODE (cond) == EQ_EXPR
1678 && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL
1679 || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL)
1680 && (TREE_CODE (TREE_OPERAND (cond, 1)) == VAR_DECL
1681 || TREE_CODE (TREE_OPERAND (cond, 1)) == PARM_DECL
1682 || TREE_CONSTANT (TREE_OPERAND (cond, 1))))
1684 var = TREE_OPERAND (cond, 0);
1685 val = TREE_OPERAND (cond, 1);
1691 /* Only work for normal local variables. */
1692 ann = var_ann (var);
1695 || TREE_ADDRESSABLE (var))
1698 if (! TREE_CONSTANT (val))
1700 ann = var_ann (val);
1703 || TREE_ADDRESSABLE (val))
1707 /* Ignore floating point variables, since comparison behaves weird for
1709 if (FLOAT_TYPE_P (TREE_TYPE (var)))
1712 for (bsi = bsi_start (bb); !bsi_end_p (bsi);)
1714 stmt = bsi_stmt (bsi);
1716 /* If the THEN/ELSE clause merely assigns a value to a variable/parameter
1717 which is already known to contain that value, then remove the useless
1718 THEN/ELSE clause. */
1719 if (TREE_CODE (stmt) == MODIFY_EXPR
1720 && TREE_OPERAND (stmt, 0) == var
1721 && operand_equal_p (val, TREE_OPERAND (stmt, 1), 0))
1727 /* Invalidate the var if we encounter something that could modify it. */
1728 if (TREE_CODE (stmt) == ASM_EXPR
1729 || TREE_CODE (stmt) == VA_ARG_EXPR
1730 || (TREE_CODE (stmt) == MODIFY_EXPR
1731 && (TREE_OPERAND (stmt, 0) == var
1732 || TREE_OPERAND (stmt, 0) == val
1733 || TREE_CODE (TREE_OPERAND (stmt, 1)) == VA_ARG_EXPR)))
1741 /* A CFG-aware version of remove_useless_stmts. */
1744 cfg_remove_useless_stmts (void)
1748 #ifdef ENABLE_CHECKING
1749 verify_flow_info ();
1754 cfg_remove_useless_stmts_bb (bb);
1759 /* Remove PHI nodes associated with basic block BB and all edges out of BB. */
1762 remove_phi_nodes_and_edges_for_unreachable_block (basic_block bb)
1766 /* Since this block is no longer reachable, we can just delete all
1767 of its PHI nodes. */
1768 phi = phi_nodes (bb);
1771 tree next = TREE_CHAIN (phi);
1772 remove_phi_node (phi, NULL_TREE, bb);
1776 /* Remove edges to BB's successors. */
1777 while (bb->succ != NULL)
1778 ssa_remove_edge (bb->succ);
1782 /* Remove statements of basic block BB. */
1785 remove_bb (basic_block bb)
1787 block_stmt_iterator i;
1788 location_t *loc = NULL;
1792 fprintf (dump_file, "Removing basic block %d\n", bb->index);
1793 if (dump_flags & TDF_DETAILS)
1795 dump_bb (bb, dump_file, 0);
1796 fprintf (dump_file, "\n");
1800 /* Remove all the instructions in the block. */
1801 for (i = bsi_start (bb); !bsi_end_p (i); bsi_remove (&i))
1803 tree stmt = bsi_stmt (i);
1805 set_bb_for_stmt (stmt, NULL);
1807 /* Don't warn for removed gotos. Gotos are often removed due to
1808 jump threading, thus resulting in bogus warnings. Not great,
1809 since this way we lose warnings for gotos in the original
1810 program that are indeed unreachable. */
1811 if (TREE_CODE (stmt) != GOTO_EXPR && EXPR_LOCUS (stmt) && !loc)
1812 loc = EXPR_LOCUS (stmt);
1815 /* If requested, give a warning that the first statement in the
1816 block is unreachable. We walk statements backwards in the
1817 loop above, so the last statement we process is the first statement
1819 if (warn_notreached && loc)
1820 warning ("%Hwill never be executed", loc);
1822 remove_phi_nodes_and_edges_for_unreachable_block (bb);
1826 /* Examine BB to determine if it is a forwarding block (a block which only
1827 transfers control to a new destination). If BB is a forwarding block,
1828 then return the edge leading to the ultimate destination. */
1831 tree_block_forwards_to (basic_block bb)
1833 block_stmt_iterator bsi;
1834 bb_ann_t ann = bb_ann (bb);
1837 /* If this block is not forwardable, then avoid useless work. */
1838 if (! ann->forwardable)
1841 /* Set this block to not be forwardable. This prevents infinite loops since
1842 any block currently under examination is considered non-forwardable. */
1843 ann->forwardable = 0;
1845 /* No forwarding is possible if this block is a special block (ENTRY/EXIT),
1846 this block has more than one successor, this block's single successor is
1847 reached via an abnormal edge, this block has phi nodes, or this block's
1848 single successor has phi nodes. */
1849 if (bb == EXIT_BLOCK_PTR
1850 || bb == ENTRY_BLOCK_PTR
1852 || bb->succ->succ_next
1853 || bb->succ->dest == EXIT_BLOCK_PTR
1854 || (bb->succ->flags & EDGE_ABNORMAL) != 0
1856 || phi_nodes (bb->succ->dest))
1859 /* Walk past any labels at the start of this block. */
1860 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
1862 stmt = bsi_stmt (bsi);
1863 if (TREE_CODE (stmt) != LABEL_EXPR)
1867 /* If we reached the end of this block we may be able to optimize this
1869 if (bsi_end_p (bsi))
1873 /* Recursive call to pick up chains of forwarding blocks. */
1874 dest = tree_block_forwards_to (bb->succ->dest);
1876 /* If none found, we forward to bb->succ at minimum. */
1880 ann->forwardable = 1;
1884 /* No forwarding possible. */
1889 /* Try to remove superfluous control structures. */
1892 cleanup_control_flow (void)
1895 block_stmt_iterator bsi;
1896 bool retval = false;
1901 bsi = bsi_last (bb);
1903 if (bsi_end_p (bsi))
1906 stmt = bsi_stmt (bsi);
1907 if (TREE_CODE (stmt) == COND_EXPR
1908 || TREE_CODE (stmt) == SWITCH_EXPR)
1909 retval |= cleanup_control_expr_graph (bb, bsi);
1915 /* Disconnect an unreachable block in the control expression starting
1919 cleanup_control_expr_graph (basic_block bb, block_stmt_iterator bsi)
1922 bool retval = false;
1923 tree expr = bsi_stmt (bsi), val;
1925 if (bb->succ->succ_next)
1929 switch (TREE_CODE (expr))
1932 val = COND_EXPR_COND (expr);
1936 val = SWITCH_COND (expr);
1937 if (TREE_CODE (val) != INTEGER_CST)
1945 taken_edge = find_taken_edge (bb, val);
1949 /* Remove all the edges except the one that is always executed. */
1950 for (e = bb->succ; e; e = next)
1952 next = e->succ_next;
1953 if (e != taken_edge)
1955 taken_edge->probability += e->probability;
1956 taken_edge->count += e->count;
1957 ssa_remove_edge (e);
1961 if (taken_edge->probability > REG_BR_PROB_BASE)
1962 taken_edge->probability = REG_BR_PROB_BASE;
1965 taken_edge = bb->succ;
1968 taken_edge->flags = EDGE_FALLTHRU;
1970 /* We removed some paths from the cfg. */
1971 if (dom_computed[CDI_DOMINATORS] >= DOM_CONS_OK)
1972 dom_computed[CDI_DOMINATORS] = DOM_CONS_OK;
1978 /* Given a control block BB and a constant value VAL, return the edge that
1979 will be taken out of the block. If VAL does not match a unique edge,
1980 NULL is returned. */
1983 find_taken_edge (basic_block bb, tree val)
1987 stmt = last_stmt (bb);
1989 #if defined ENABLE_CHECKING
1990 if (stmt == NULL_TREE || !is_ctrl_stmt (stmt))
1994 /* If VAL is not a constant, we can't determine which edge might
1996 if (val == NULL || !really_constant_p (val))
1999 if (TREE_CODE (stmt) == COND_EXPR)
2000 return find_taken_edge_cond_expr (bb, val);
2002 if (TREE_CODE (stmt) == SWITCH_EXPR)
2003 return find_taken_edge_switch_expr (bb, val);
2009 /* Given a constant value VAL and the entry block BB to a COND_EXPR
2010 statement, determine which of the two edges will be taken out of the
2011 block. Return NULL if either edge may be taken. */
2014 find_taken_edge_cond_expr (basic_block bb, tree val)
2016 edge true_edge, false_edge;
2018 extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
2020 /* If both edges of the branch lead to the same basic block, it doesn't
2021 matter which edge is taken. */
2022 if (true_edge->dest == false_edge->dest)
2025 /* Otherwise, try to determine which branch of the if() will be taken.
2026 If VAL is a constant but it can't be reduced to a 0 or a 1, then
2027 we don't really know which edge will be taken at runtime. This
2028 may happen when comparing addresses (e.g., if (&var1 == 4)). */
2029 if (integer_nonzerop (val))
2031 else if (integer_zerop (val))
2038 /* Given a constant value VAL and the entry block BB to a SWITCH_EXPR
2039 statement, determine which edge will be taken out of the block. Return
2040 NULL if any edge may be taken. */
2043 find_taken_edge_switch_expr (basic_block bb, tree val)
2045 tree switch_expr, taken_case;
2046 basic_block dest_bb;
2049 if (TREE_CODE (val) != INTEGER_CST)
2052 switch_expr = last_stmt (bb);
2053 taken_case = find_case_label_for_value (switch_expr, val);
2054 dest_bb = label_to_block (CASE_LABEL (taken_case));
2056 e = find_edge (bb, dest_bb);
2063 /* Return the CASE_LABEL_EXPR that SWITCH_EXPR will take for VAL.
2064 We can make optimal use here of the fact that the case labels are
2065 sorted: We can do a binary search for a case matching VAL. */
2068 find_case_label_for_value (tree switch_expr, tree val)
2070 tree vec = SWITCH_LABELS (switch_expr);
2071 size_t low, high, n = TREE_VEC_LENGTH (vec);
2072 tree default_case = TREE_VEC_ELT (vec, n - 1);
2074 for (low = -1, high = n - 1; high - low > 1; )
2076 size_t i = (high + low) / 2;
2077 tree t = TREE_VEC_ELT (vec, i);
2080 /* Cache the result of comparing CASE_LOW and val. */
2081 cmp = tree_int_cst_compare (CASE_LOW (t), val);
2088 if (CASE_HIGH (t) == NULL)
2090 /* A singe-valued case label. */
2096 /* A case range. We can only handle integer ranges. */
2097 if (cmp <= 0 && tree_int_cst_compare (CASE_HIGH (t), val) >= 0)
2102 return default_case;
2106 /* If all the PHI nodes in DEST have alternatives for E1 and E2 and
2107 those alternatives are equal in each of the PHI nodes, then return
2108 true, else return false. */
2111 phi_alternatives_equal (basic_block dest, edge e1, edge e2)
2113 tree phi, val1, val2;
2116 for (phi = phi_nodes (dest); phi; phi = TREE_CHAIN (phi))
2118 n1 = phi_arg_from_edge (phi, e1);
2119 n2 = phi_arg_from_edge (phi, e2);
2121 #ifdef ENABLE_CHECKING
2122 if (n1 < 0 || n2 < 0)
2126 val1 = PHI_ARG_DEF (phi, n1);
2127 val2 = PHI_ARG_DEF (phi, n2);
2129 if (!operand_equal_p (val1, val2, 0))
2137 /* Computing the Dominance Frontier:
2139 As described in Morgan, section 3.5, this may be done simply by
2140 walking the dominator tree bottom-up, computing the frontier for
2141 the children before the parent. When considering a block B,
2142 there are two cases:
2144 (1) A flow graph edge leaving B that does not lead to a child
2145 of B in the dominator tree must be a block that is either equal
2146 to B or not dominated by B. Such blocks belong in the frontier
2149 (2) Consider a block X in the frontier of one of the children C
2150 of B. If X is not equal to B and is not dominated by B, it
2151 is in the frontier of B. */
2154 compute_dominance_frontiers_1 (bitmap *frontiers, basic_block bb, sbitmap done)
2159 SET_BIT (done, bb->index);
2161 /* Do the frontier of the children first. Not all children in the
2162 dominator tree (blocks dominated by this one) are children in the
2163 CFG, so check all blocks. */
2164 for (c = first_dom_son (CDI_DOMINATORS, bb);
2166 c = next_dom_son (CDI_DOMINATORS, c))
2168 if (! TEST_BIT (done, c->index))
2169 compute_dominance_frontiers_1 (frontiers, c, done);
2172 /* Find blocks conforming to rule (1) above. */
2173 for (e = bb->succ; e; e = e->succ_next)
2175 if (e->dest == EXIT_BLOCK_PTR)
2177 if (get_immediate_dominator (CDI_DOMINATORS, e->dest) != bb)
2178 bitmap_set_bit (frontiers[bb->index], e->dest->index);
2181 /* Find blocks conforming to rule (2). */
2182 for (c = first_dom_son (CDI_DOMINATORS, bb);
2184 c = next_dom_son (CDI_DOMINATORS, c))
2188 EXECUTE_IF_SET_IN_BITMAP (frontiers[c->index], 0, x,
2190 if (get_immediate_dominator (CDI_DOMINATORS, BASIC_BLOCK (x)) != bb)
2191 bitmap_set_bit (frontiers[bb->index], x);
2198 compute_dominance_frontiers (bitmap *frontiers)
2200 sbitmap done = sbitmap_alloc (last_basic_block);
2202 timevar_push (TV_DOM_FRONTIERS);
2204 sbitmap_zero (done);
2206 compute_dominance_frontiers_1 (frontiers, ENTRY_BLOCK_PTR->succ->dest, done);
2208 sbitmap_free (done);
2210 timevar_pop (TV_DOM_FRONTIERS);
2215 /*---------------------------------------------------------------------------
2217 ---------------------------------------------------------------------------*/
2219 /* Dump tree-specific information of block BB to file OUTF. */
2222 tree_dump_bb (basic_block bb, FILE *outf, int indent)
2224 dump_generic_bb (outf, bb, indent, TDF_VOPS);
2228 /* Dump a basic block on stderr. */
2231 debug_tree_bb (basic_block bb)
2233 dump_bb (bb, stderr, 0);
2237 /* Dump basic block with index N on stderr. */
2240 debug_tree_bb_n (int n)
2242 debug_tree_bb (BASIC_BLOCK (n));
2243 return BASIC_BLOCK (n);
2247 /* Dump the CFG on stderr.
2249 FLAGS are the same used by the tree dumping functions
2250 (see TDF_* in tree.h). */
2253 debug_tree_cfg (int flags)
2255 dump_tree_cfg (stderr, flags);
2259 /* Dump the program showing basic block boundaries on the given FILE.
2261 FLAGS are the same used by the tree dumping functions (see TDF_* in
2265 dump_tree_cfg (FILE *file, int flags)
2267 if (flags & TDF_DETAILS)
2269 const char *funcname
2270 = lang_hooks.decl_printable_name (current_function_decl, 2);
2273 fprintf (file, ";; Function %s\n\n", funcname);
2274 fprintf (file, ";; \n%d basic blocks, %d edges, last basic block %d.\n\n",
2275 n_basic_blocks, n_edges, last_basic_block);
2277 brief_dump_cfg (file);
2278 fprintf (file, "\n");
2281 if (flags & TDF_STATS)
2282 dump_cfg_stats (file);
2284 dump_function_to_file (current_function_decl, file, flags | TDF_BLOCKS);
2288 /* Dump CFG statistics on FILE. */
2291 dump_cfg_stats (FILE *file)
2293 static long max_num_merged_labels = 0;
2294 unsigned long size, total = 0;
2297 const char * const fmt_str = "%-30s%-13s%12s\n";
2298 const char * const fmt_str_1 = "%-30s%13lu%11lu%c\n";
2299 const char * const fmt_str_3 = "%-43s%11lu%c\n";
2300 const char *funcname
2301 = lang_hooks.decl_printable_name (current_function_decl, 2);
2304 fprintf (file, "\nCFG Statistics for %s\n\n", funcname);
2306 fprintf (file, "---------------------------------------------------------\n");
2307 fprintf (file, fmt_str, "", " Number of ", "Memory");
2308 fprintf (file, fmt_str, "", " instances ", "used ");
2309 fprintf (file, "---------------------------------------------------------\n");
2311 size = n_basic_blocks * sizeof (struct basic_block_def);
2313 fprintf (file, fmt_str_1, "Basic blocks", n_basic_blocks, SCALE (size),
2320 for (e = bb->succ; e; e = e->succ_next)
2323 size = n_edges * sizeof (struct edge_def);
2325 fprintf (file, fmt_str_1, "Edges", n_edges, SCALE (size), LABEL (size));
2327 size = n_basic_blocks * sizeof (struct bb_ann_d);
2329 fprintf (file, fmt_str_1, "Basic block annotations", n_basic_blocks,
2330 SCALE (size), LABEL (size));
2332 fprintf (file, "---------------------------------------------------------\n");
2333 fprintf (file, fmt_str_3, "Total memory used by CFG data", SCALE (total),
2335 fprintf (file, "---------------------------------------------------------\n");
2336 fprintf (file, "\n");
2338 if (cfg_stats.num_merged_labels > max_num_merged_labels)
2339 max_num_merged_labels = cfg_stats.num_merged_labels;
2341 fprintf (file, "Coalesced label blocks: %ld (Max so far: %ld)\n",
2342 cfg_stats.num_merged_labels, max_num_merged_labels);
2344 fprintf (file, "\n");
2348 /* Dump CFG statistics on stderr. Keep extern so that it's always
2349 linked in the final executable. */
2352 debug_cfg_stats (void)
2354 dump_cfg_stats (stderr);
2358 /* Dump the flowgraph to a .vcg FILE. */
2361 tree_cfg2vcg (FILE *file)
2365 const char *funcname
2366 = lang_hooks.decl_printable_name (current_function_decl, 2);
2368 /* Write the file header. */
2369 fprintf (file, "graph: { title: \"%s\"\n", funcname);
2370 fprintf (file, "node: { title: \"ENTRY\" label: \"ENTRY\" }\n");
2371 fprintf (file, "node: { title: \"EXIT\" label: \"EXIT\" }\n");
2373 /* Write blocks and edges. */
2374 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
2376 fprintf (file, "edge: { sourcename: \"ENTRY\" targetname: \"%d\"",
2379 if (e->flags & EDGE_FAKE)
2380 fprintf (file, " linestyle: dotted priority: 10");
2382 fprintf (file, " linestyle: solid priority: 100");
2384 fprintf (file, " }\n");
2390 enum tree_code head_code, end_code;
2391 const char *head_name, *end_name;
2394 tree first = first_stmt (bb);
2395 tree last = last_stmt (bb);
2399 head_code = TREE_CODE (first);
2400 head_name = tree_code_name[head_code];
2401 head_line = get_lineno (first);
2404 head_name = "no-statement";
2408 end_code = TREE_CODE (last);
2409 end_name = tree_code_name[end_code];
2410 end_line = get_lineno (last);
2413 end_name = "no-statement";
2415 fprintf (file, "node: { title: \"%d\" label: \"#%d\\n%s (%d)\\n%s (%d)\"}\n",
2416 bb->index, bb->index, head_name, head_line, end_name,
2419 for (e = bb->succ; e; e = e->succ_next)
2421 if (e->dest == EXIT_BLOCK_PTR)
2422 fprintf (file, "edge: { sourcename: \"%d\" targetname: \"EXIT\"", bb->index);
2424 fprintf (file, "edge: { sourcename: \"%d\" targetname: \"%d\"", bb->index, e->dest->index);
2426 if (e->flags & EDGE_FAKE)
2427 fprintf (file, " priority: 10 linestyle: dotted");
2429 fprintf (file, " priority: 100 linestyle: solid");
2431 fprintf (file, " }\n");
2434 if (bb->next_bb != EXIT_BLOCK_PTR)
2438 fputs ("}\n\n", file);
2443 /*---------------------------------------------------------------------------
2444 Miscellaneous helpers
2445 ---------------------------------------------------------------------------*/
2447 /* Return true if T represents a stmt that always transfers control. */
2450 is_ctrl_stmt (tree t)
2452 return (TREE_CODE (t) == COND_EXPR
2453 || TREE_CODE (t) == SWITCH_EXPR
2454 || TREE_CODE (t) == GOTO_EXPR
2455 || TREE_CODE (t) == RETURN_EXPR
2456 || TREE_CODE (t) == RESX_EXPR);
2460 /* Return true if T is a statement that may alter the flow of control
2461 (e.g., a call to a non-returning function). */
2464 is_ctrl_altering_stmt (tree t)
2468 #if defined ENABLE_CHECKING
2473 switch (TREE_CODE (t))
2476 /* A MODIFY_EXPR with a rhs of a call has the characteristics
2478 call = TREE_OPERAND (t, 1);
2479 if (TREE_CODE (call) != CALL_EXPR)
2484 /* A non-pure/const CALL_EXPR alters flow control if the current
2485 function has nonlocal labels. */
2486 if (TREE_SIDE_EFFECTS (t)
2487 && current_function_has_nonlocal_label)
2490 /* A CALL_EXPR also alters control flow if it does not return. */
2491 if (call_expr_flags (call) & (ECF_NORETURN | ECF_LONGJMP))
2499 /* If a statement can throw, it alters control flow. */
2500 return tree_can_throw_internal (t);
2504 /* Return true if T is a computed goto. */
2507 computed_goto_p (tree t)
2509 return (TREE_CODE (t) == GOTO_EXPR
2510 && TREE_CODE (GOTO_DESTINATION (t)) != LABEL_DECL);
2514 /* Checks whether EXPR is a simple local goto. */
2517 simple_goto_p (tree expr)
2519 return (TREE_CODE (expr) == GOTO_EXPR
2520 && TREE_CODE (GOTO_DESTINATION (expr)) == LABEL_DECL
2521 && (decl_function_context (GOTO_DESTINATION (expr))
2522 == current_function_decl));
2526 /* Return true if T should start a new basic block. PREV_T is the
2527 statement preceding T. It is used when T is a label or a case label.
2528 Labels should only start a new basic block if their previous statement
2529 wasn't a label. Otherwise, sequence of labels would generate
2530 unnecessary basic blocks that only contain a single label. */
2533 stmt_starts_bb_p (tree t, tree prev_t)
2535 enum tree_code code;
2540 /* LABEL_EXPRs start a new basic block only if the preceding
2541 statement wasn't a label of the same type. This prevents the
2542 creation of consecutive blocks that have nothing but a single
2544 code = TREE_CODE (t);
2545 if (code == LABEL_EXPR)
2547 /* Nonlocal and computed GOTO targets always start a new block. */
2548 if (code == LABEL_EXPR
2549 && (DECL_NONLOCAL (LABEL_EXPR_LABEL (t))
2550 || FORCED_LABEL (LABEL_EXPR_LABEL (t))))
2553 if (prev_t && TREE_CODE (prev_t) == code)
2555 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (prev_t)))
2558 cfg_stats.num_merged_labels++;
2569 /* Return true if T should end a basic block. */
2572 stmt_ends_bb_p (tree t)
2574 return is_ctrl_stmt (t) || is_ctrl_altering_stmt (t);
2578 /* Add gotos that used to be represented implicitly in the CFG. */
2581 disband_implicit_edges (void)
2584 block_stmt_iterator last;
2586 tree stmt, label, forward;
2590 last = bsi_last (bb);
2591 stmt = last_stmt (bb);
2593 if (stmt && TREE_CODE (stmt) == COND_EXPR)
2595 /* Remove superfluous gotos from COND_EXPR branches. Moved
2596 from cfg_remove_useless_stmts here since it violates the
2597 invariants for tree--cfg correspondence and thus fits better
2598 here where we do it anyway. */
2599 for (e = bb->succ; e; e = e->succ_next)
2601 if (e->dest != bb->next_bb)
2604 if (e->flags & EDGE_TRUE_VALUE)
2605 COND_EXPR_THEN (stmt) = build_empty_stmt ();
2606 else if (e->flags & EDGE_FALSE_VALUE)
2607 COND_EXPR_ELSE (stmt) = build_empty_stmt ();
2610 e->flags |= EDGE_FALLTHRU;
2616 if (stmt && TREE_CODE (stmt) == RETURN_EXPR)
2618 /* Remove the RETURN_EXPR if we may fall though to the exit
2621 || bb->succ->succ_next
2622 || bb->succ->dest != EXIT_BLOCK_PTR)
2625 if (bb->next_bb == EXIT_BLOCK_PTR
2626 && !TREE_OPERAND (stmt, 0))
2629 bb->succ->flags |= EDGE_FALLTHRU;
2634 /* There can be no fallthru edge if the last statement is a control
2636 if (stmt && is_ctrl_stmt (stmt))
2639 /* Find a fallthru edge and emit the goto if necessary. */
2640 for (e = bb->succ; e; e = e->succ_next)
2641 if (e->flags & EDGE_FALLTHRU)
2644 if (!e || e->dest == bb->next_bb)
2647 if (e->dest == EXIT_BLOCK_PTR)
2650 label = tree_block_label (e->dest);
2652 /* If this is a goto to a goto, jump to the final destination.
2653 Handles unfactoring of the computed jumps.
2654 ??? Why bother putting this back together when rtl is just
2655 about to take it apart again? */
2656 forward = last_and_only_stmt (e->dest);
2658 && TREE_CODE (forward) == GOTO_EXPR)
2659 label = GOTO_DESTINATION (forward);
2661 stmt = build1 (GOTO_EXPR, void_type_node, label);
2662 SET_EXPR_LOCUS (stmt, e->goto_locus);
2663 bsi_insert_after (&last, stmt, BSI_NEW_STMT);
2664 e->flags &= ~EDGE_FALLTHRU;
2669 /* Remove all the blocks and edges that make up the flowgraph. */
2672 delete_tree_cfg (void)
2674 if (n_basic_blocks > 0)
2675 free_blocks_annotations ();
2677 free_basic_block_vars ();
2678 basic_block_info = NULL;
2679 label_to_block_map = NULL;
2684 /* Return the first statement in basic block BB. */
2687 first_stmt (basic_block bb)
2689 block_stmt_iterator i = bsi_start (bb);
2690 return !bsi_end_p (i) ? bsi_stmt (i) : NULL_TREE;
2694 /* Return the last statement in basic block BB. */
2697 last_stmt (basic_block bb)
2699 block_stmt_iterator b = bsi_last (bb);
2700 return !bsi_end_p (b) ? bsi_stmt (b) : NULL_TREE;
2704 /* Return a pointer to the last statement in block BB. */
2707 last_stmt_ptr (basic_block bb)
2709 block_stmt_iterator last = bsi_last (bb);
2710 return !bsi_end_p (last) ? bsi_stmt_ptr (last) : NULL;
2714 /* Return the last statement of an otherwise empty block. Return NULL
2715 if the block is totally empty, or if it contains more than one
2719 last_and_only_stmt (basic_block bb)
2721 block_stmt_iterator i = bsi_last (bb);
2727 last = bsi_stmt (i);
2732 /* Empty statements should no longer appear in the instruction stream.
2733 Everything that might have appeared before should be deleted by
2734 remove_useless_stmts, and the optimizers should just bsi_remove
2735 instead of smashing with build_empty_stmt.
2737 Thus the only thing that should appear here in a block containing
2738 one executable statement is a label. */
2739 prev = bsi_stmt (i);
2740 if (TREE_CODE (prev) == LABEL_EXPR)
2747 /* Mark BB as the basic block holding statement T. */
2750 set_bb_for_stmt (tree t, basic_block bb)
2752 if (TREE_CODE (t) == STATEMENT_LIST)
2754 tree_stmt_iterator i;
2755 for (i = tsi_start (t); !tsi_end_p (i); tsi_next (&i))
2756 set_bb_for_stmt (tsi_stmt (i), bb);
2760 stmt_ann_t ann = get_stmt_ann (t);
2763 /* If the statement is a label, add the label to block-to-labels map
2764 so that we can speed up edge creation for GOTO_EXPRs. */
2765 if (TREE_CODE (t) == LABEL_EXPR)
2769 t = LABEL_EXPR_LABEL (t);
2770 uid = LABEL_DECL_UID (t);
2773 LABEL_DECL_UID (t) = uid = cfun->last_label_uid++;
2774 if (VARRAY_SIZE (label_to_block_map) <= (unsigned) uid)
2775 VARRAY_GROW (label_to_block_map, 3 * uid / 2);
2779 #ifdef ENABLE_CHECKING
2780 /* We're moving an existing label. Make sure that we've
2781 removed it from the old block. */
2782 if (bb && VARRAY_BB (label_to_block_map, uid))
2786 VARRAY_BB (label_to_block_map, uid) = bb;
2792 /* Insert statement (or statement list) T before the statement
2793 pointed-to by iterator I. M specifies how to update iterator I
2794 after insertion (see enum bsi_iterator_update). */
2797 bsi_insert_before (block_stmt_iterator *i, tree t, enum bsi_iterator_update m)
2799 set_bb_for_stmt (t, i->bb);
2801 tsi_link_before (&i->tsi, t, m);
2805 /* Insert statement (or statement list) T after 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_after (block_stmt_iterator *i, tree t, enum bsi_iterator_update m)
2812 set_bb_for_stmt (t, i->bb);
2814 tsi_link_after (&i->tsi, t, m);
2818 /* Remove the statement pointed to by iterator I. The iterator is updated
2819 to the next statement. */
2822 bsi_remove (block_stmt_iterator *i)
2824 tree t = bsi_stmt (*i);
2825 set_bb_for_stmt (t, NULL);
2827 tsi_delink (&i->tsi);
2831 /* Move the statement at FROM so it comes right after the statement at TO. */
2834 bsi_move_after (block_stmt_iterator *from, block_stmt_iterator *to)
2836 tree stmt = bsi_stmt (*from);
2838 bsi_insert_after (to, stmt, BSI_SAME_STMT);
2842 /* Move the statement at FROM so it comes right before the statement at TO. */
2845 bsi_move_before (block_stmt_iterator *from, block_stmt_iterator *to)
2847 tree stmt = bsi_stmt (*from);
2849 bsi_insert_before (to, stmt, BSI_SAME_STMT);
2853 /* Move the statement at FROM to the end of basic block BB. */
2856 bsi_move_to_bb_end (block_stmt_iterator *from, basic_block bb)
2858 block_stmt_iterator last = bsi_last (bb);
2860 /* Have to check bsi_end_p because it could be an empty block. */
2861 if (!bsi_end_p (last) && is_ctrl_stmt (bsi_stmt (last)))
2862 bsi_move_before (from, &last);
2864 bsi_move_after (from, &last);
2868 /* Replace the contents of the statement pointed to by iterator BSI
2869 with STMT. If PRESERVE_EH_INFO is true, the exception handling
2870 information of the original statement is preserved. */
2873 bsi_replace (const block_stmt_iterator *bsi, tree stmt, bool preserve_eh_info)
2876 tree orig_stmt = bsi_stmt (*bsi);
2878 SET_EXPR_LOCUS (stmt, EXPR_LOCUS (orig_stmt));
2879 set_bb_for_stmt (stmt, bsi->bb);
2881 /* Preserve EH region information from the original statement, if
2882 requested by the caller. */
2883 if (preserve_eh_info)
2885 eh_region = lookup_stmt_eh_region (orig_stmt);
2887 add_stmt_to_eh_region (stmt, eh_region);
2890 *bsi_stmt_ptr (*bsi) = stmt;
2895 /* Insert the statement pointed-to by BSI into edge E. Every attempt
2896 is made to place the statement in an existing basic block, but
2897 sometimes that isn't possible. When it isn't possible, the edge is
2898 split and the statement is added to the new block.
2900 In all cases, the returned *BSI points to the correct location. The
2901 return value is true if insertion should be done after the location,
2902 or false if it should be done before the location. */
2905 tree_find_edge_insert_loc (edge e, block_stmt_iterator *bsi)
2907 basic_block dest, src;
2913 /* If the destination has one predecessor which has no PHI nodes,
2914 insert there. Except for the exit block.
2916 The requirement for no PHI nodes could be relaxed. Basically we
2917 would have to examine the PHIs to prove that none of them used
2918 the value set by the statement we want to insert on E. That
2919 hardly seems worth the effort. */
2920 if (dest->pred->pred_next == NULL
2921 && ! phi_nodes (dest)
2922 && dest != EXIT_BLOCK_PTR)
2924 *bsi = bsi_start (dest);
2925 if (bsi_end_p (*bsi))
2928 /* Make sure we insert after any leading labels. */
2929 tmp = bsi_stmt (*bsi);
2930 while (TREE_CODE (tmp) == LABEL_EXPR)
2933 if (bsi_end_p (*bsi))
2935 tmp = bsi_stmt (*bsi);
2938 if (bsi_end_p (*bsi))
2940 *bsi = bsi_last (dest);
2947 /* If the source has one successor, the edge is not abnormal and
2948 the last statement does not end a basic block, insert there.
2949 Except for the entry block. */
2951 if ((e->flags & EDGE_ABNORMAL) == 0
2952 && src->succ->succ_next == NULL
2953 && src != ENTRY_BLOCK_PTR)
2955 *bsi = bsi_last (src);
2956 if (bsi_end_p (*bsi))
2959 tmp = bsi_stmt (*bsi);
2960 if (!stmt_ends_bb_p (tmp))
2963 /* Insert code just before returning the value. We may need to decompose
2964 the return in the case it contains non-trivial operand. */
2965 if (TREE_CODE (tmp) == RETURN_EXPR)
2967 tree op = TREE_OPERAND (tmp, 0);
2968 if (!is_gimple_val (op))
2970 if (TREE_CODE (op) != MODIFY_EXPR)
2972 bsi_insert_before (bsi, op, BSI_NEW_STMT);
2973 TREE_OPERAND (tmp, 0) = TREE_OPERAND (op, 0);
2980 /* Otherwise, create a new basic block, and split this edge. */
2981 dest = split_edge (e);
2987 /* This routine will commit all pending edge insertions, creating any new
2988 basic blocks which are necessary.
2990 If specified, NEW_BLOCKS returns a count of the number of new basic
2991 blocks which were created. */
2994 bsi_commit_edge_inserts (int *new_blocks)
3000 blocks = n_basic_blocks;
3002 bsi_commit_edge_inserts_1 (ENTRY_BLOCK_PTR->succ);
3005 for (e = bb->succ; e; e = e->succ_next)
3006 bsi_commit_edge_inserts_1 (e);
3009 *new_blocks = n_basic_blocks - blocks;
3013 /* Commit insertions pending at edge E. */
3016 bsi_commit_edge_inserts_1 (edge e)
3018 if (PENDING_STMT (e))
3020 block_stmt_iterator bsi;
3021 tree stmt = PENDING_STMT (e);
3023 PENDING_STMT (e) = NULL_TREE;
3025 if (tree_find_edge_insert_loc (e, &bsi))
3026 bsi_insert_after (&bsi, stmt, BSI_NEW_STMT);
3028 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
3033 /* Add STMT to the pending list of edge E. No actual insertion is
3034 made until a call to bsi_commit_edge_inserts () is made. */
3037 bsi_insert_on_edge (edge e, tree stmt)
3039 append_to_statement_list (stmt, &PENDING_STMT (e));
3043 /* Specialized edge insertion for SSA-PRE. FIXME: This should
3044 probably disappear. The only reason it's here is because PRE needs
3045 the call to tree_find_edge_insert_loc(). */
3047 void pre_insert_on_edge (edge e, tree stmt);
3050 pre_insert_on_edge (edge e, tree stmt)
3052 block_stmt_iterator bsi;
3054 if (PENDING_STMT (e))
3057 if (tree_find_edge_insert_loc (e, &bsi))
3058 bsi_insert_after (&bsi, stmt, BSI_NEW_STMT);
3060 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
3064 /*---------------------------------------------------------------------------
3065 Tree specific functions for CFG manipulation
3066 ---------------------------------------------------------------------------*/
3068 /* Split a (typically critical) edge EDGE_IN. Return the new block.
3069 Abort on abnormal edges. */
3072 tree_split_edge (edge edge_in)
3074 basic_block new_bb, after_bb, dest, src;
3079 /* Abnormal edges cannot be split. */
3080 if (edge_in->flags & EDGE_ABNORMAL)
3084 dest = edge_in->dest;
3086 /* Place the new block in the block list. Try to keep the new block
3087 near its "logical" location. This is of most help to humans looking
3088 at debugging dumps. */
3089 for (e = dest->pred; e; e = e->pred_next)
3090 if (e->src->next_bb == dest)
3093 after_bb = dest->prev_bb;
3095 after_bb = edge_in->src;
3097 new_bb = create_empty_bb (after_bb);
3098 new_edge = make_edge (new_bb, dest, EDGE_FALLTHRU);
3100 /* Find all the PHI arguments on the original edge, and change them to
3101 the new edge. Do it before redirection, so that the argument does not
3103 for (phi = phi_nodes (dest); phi; phi = TREE_CHAIN (phi))
3105 num_elem = PHI_NUM_ARGS (phi);
3106 for (i = 0; i < num_elem; i++)
3107 if (PHI_ARG_EDGE (phi, i) == edge_in)
3109 PHI_ARG_EDGE (phi, i) = new_edge;
3114 if (!redirect_edge_and_branch (edge_in, new_bb))
3117 if (PENDING_STMT (edge_in))
3124 /* Return true when BB has label LABEL in it. */
3127 has_label_p (basic_block bb, tree label)
3129 block_stmt_iterator bsi;
3131 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3133 tree stmt = bsi_stmt (bsi);
3135 if (TREE_CODE (stmt) != LABEL_EXPR)
3137 if (LABEL_EXPR_LABEL (stmt) == label)
3144 /* Callback for walk_tree, check that all elements with address taken are
3145 properly noticed as such. */
3148 verify_expr (tree *tp, int *walk_subtrees ATTRIBUTE_UNUSED,
3149 void *data ATTRIBUTE_UNUSED)
3156 switch (TREE_CODE (t))
3159 if (SSA_NAME_IN_FREE_LIST (t))
3161 error ("SSA name in freelist but still referenced");
3167 x = TREE_OPERAND (t, 0);
3168 if (TREE_CODE (x) == BIT_FIELD_REF
3169 && is_gimple_reg (TREE_OPERAND (x, 0)))
3171 error ("GIMPLE register modified with BIT_FIELD_REF");
3177 x = TREE_OPERAND (t, 0);
3178 while (TREE_CODE (x) == ARRAY_REF
3179 || TREE_CODE (x) == COMPONENT_REF
3180 || TREE_CODE (x) == REALPART_EXPR
3181 || TREE_CODE (x) == IMAGPART_EXPR)
3182 x = TREE_OPERAND (x, 0);
3183 if (TREE_CODE (x) != VAR_DECL && TREE_CODE (x) != PARM_DECL)
3185 if (!TREE_ADDRESSABLE (x))
3187 error ("address taken, but ADDRESSABLE bit not set");
3193 x = TREE_OPERAND (t, 0);
3194 if (TREE_CODE (TREE_TYPE (x)) != BOOLEAN_TYPE)
3196 error ("non-boolean used in condition");
3203 case FIX_TRUNC_EXPR:
3205 case FIX_FLOOR_EXPR:
3206 case FIX_ROUND_EXPR:
3211 case NON_LVALUE_EXPR:
3212 case TRUTH_NOT_EXPR:
3213 x = TREE_OPERAND (t, 0);
3214 /* We check for constants explicitly since they are not considered
3215 gimple invariants if they overflowed. */
3216 if (TREE_CODE_CLASS (TREE_CODE (x)) != 'c'
3217 && !is_gimple_val (x))
3219 error ("Invalid operand to unary operator");
3234 case UNORDERED_EXPR:
3245 case TRUNC_DIV_EXPR:
3247 case FLOOR_DIV_EXPR:
3248 case ROUND_DIV_EXPR:
3249 case TRUNC_MOD_EXPR:
3251 case FLOOR_MOD_EXPR:
3252 case ROUND_MOD_EXPR:
3254 case EXACT_DIV_EXPR:
3264 x = TREE_OPERAND (t, 0);
3265 /* We check for constants explicitly since they are not considered
3266 gimple invariants if they overflowed. */
3267 if (TREE_CODE_CLASS (TREE_CODE (x)) != 'c'
3268 && !is_gimple_val (x))
3270 error ("Invalid operand to binary operator");
3273 x = TREE_OPERAND (t, 1);
3274 /* We check for constants explicitly since they are not considered
3275 gimple invariants if they overflowed. */
3276 if (TREE_CODE_CLASS (TREE_CODE (x)) != 'c'
3277 && !is_gimple_val (x))
3279 error ("Invalid operand to binary operator");
3291 /* Verify STMT, return true if STMT is not in GIMPLE form.
3292 TODO: Implement type checking. */
3295 verify_stmt (tree stmt)
3299 if (!is_gimple_stmt (stmt))
3301 error ("Is not a valid GIMPLE statement.");
3302 debug_generic_stmt (stmt);
3306 addr = walk_tree (&stmt, verify_expr, NULL, NULL);
3309 debug_generic_stmt (addr);
3317 /* Return true when the T can be shared. */
3320 tree_node_can_be_shared (tree t)
3322 if (TYPE_P (t) || DECL_P (t)
3323 /* We check for constants explicitly since they are not considered
3324 gimple invariants if they overflowed. */
3325 || TREE_CODE_CLASS (TREE_CODE (t)) == 'c'
3326 || is_gimple_min_invariant (t)
3327 || TREE_CODE (t) == SSA_NAME)
3330 while ((TREE_CODE (t) == ARRAY_REF
3331 /* We check for constants explicitly since they are not considered
3332 gimple invariants if they overflowed. */
3333 && (TREE_CODE_CLASS (TREE_CODE (TREE_OPERAND (t, 1))) == 'c'
3334 || is_gimple_min_invariant (TREE_OPERAND (t, 1))))
3335 || (TREE_CODE (t) == COMPONENT_REF
3336 || TREE_CODE (t) == REALPART_EXPR
3337 || TREE_CODE (t) == IMAGPART_EXPR))
3338 t = TREE_OPERAND (t, 0);
3347 /* Called via walk_trees. Verify tree sharing. */
3350 verify_node_sharing (tree * tp, int *walk_subtrees, void *data)
3352 htab_t htab = (htab_t) data;
3355 if (tree_node_can_be_shared (*tp))
3357 *walk_subtrees = false;
3361 slot = htab_find_slot (htab, *tp, INSERT);
3370 /* Verify the GIMPLE statement chain. */
3376 block_stmt_iterator bsi;
3381 timevar_push (TV_TREE_STMT_VERIFY);
3382 htab = htab_create (37, htab_hash_pointer, htab_eq_pointer, NULL);
3389 for (phi = phi_nodes (bb); phi; phi = TREE_CHAIN (phi))
3391 int phi_num_args = PHI_NUM_ARGS (phi);
3393 for (i = 0; i < phi_num_args; i++)
3395 tree t = PHI_ARG_DEF (phi, i);
3398 /* Addressable variables do have SSA_NAMEs but they
3399 are not considered gimple values. */
3400 if (TREE_CODE (t) != SSA_NAME
3401 && TREE_CODE (t) != FUNCTION_DECL
3402 && !is_gimple_val (t))
3404 error ("PHI def is not a GIMPLE value");
3405 debug_generic_stmt (phi);
3406 debug_generic_stmt (t);
3410 addr = walk_tree (&t, verify_expr, NULL, NULL);
3413 debug_generic_stmt (addr);
3417 addr = walk_tree (&t, verify_node_sharing, htab, NULL);
3420 error ("Incorrect sharing of tree nodes");
3421 debug_generic_stmt (phi);
3422 debug_generic_stmt (addr);
3428 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3430 tree stmt = bsi_stmt (bsi);
3431 err |= verify_stmt (stmt);
3432 addr = walk_tree (&stmt, verify_node_sharing, htab, NULL);
3435 error ("Incorrect sharing of tree nodes");
3436 debug_generic_stmt (stmt);
3437 debug_generic_stmt (addr);
3444 internal_error ("verify_stmts failed.");
3447 timevar_pop (TV_TREE_STMT_VERIFY);
3451 /* Verifies that the flow information is OK. */
3454 tree_verify_flow_info (void)
3458 block_stmt_iterator bsi;
3462 if (ENTRY_BLOCK_PTR->stmt_list)
3464 error ("ENTRY_BLOCK has a statement list associated with it\n");
3468 if (EXIT_BLOCK_PTR->stmt_list)
3470 error ("EXIT_BLOCK has a statement list associated with it\n");
3474 for (e = EXIT_BLOCK_PTR->pred; e; e = e->pred_next)
3475 if (e->flags & EDGE_FALLTHRU)
3477 error ("Fallthru to exit from bb %d\n", e->src->index);
3483 bool found_ctrl_stmt = false;
3485 /* Skip labels on the start of basic block. */
3486 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3488 if (TREE_CODE (bsi_stmt (bsi)) != LABEL_EXPR)
3491 if (label_to_block (LABEL_EXPR_LABEL (bsi_stmt (bsi))) != bb)
3493 error ("Label %s to block does not match in bb %d\n",
3494 IDENTIFIER_POINTER (DECL_NAME (bsi_stmt (bsi))),
3499 if (decl_function_context (LABEL_EXPR_LABEL (bsi_stmt (bsi)))
3500 != current_function_decl)
3502 error ("Label %s has incorrect context in bb %d\n",
3503 IDENTIFIER_POINTER (DECL_NAME (bsi_stmt (bsi))),
3509 /* Verify that body of basic block BB is free of control flow. */
3510 for (; !bsi_end_p (bsi); bsi_next (&bsi))
3512 tree stmt = bsi_stmt (bsi);
3514 if (found_ctrl_stmt)
3516 error ("Control flow in the middle of basic block %d\n",
3521 if (stmt_ends_bb_p (stmt))
3522 found_ctrl_stmt = true;
3524 if (TREE_CODE (stmt) == LABEL_EXPR)
3526 error ("Label %s in the middle of basic block %d\n",
3527 IDENTIFIER_POINTER (DECL_NAME (stmt)),
3532 bsi = bsi_last (bb);
3533 if (bsi_end_p (bsi))
3536 stmt = bsi_stmt (bsi);
3538 if (is_ctrl_stmt (stmt))
3540 for (e = bb->succ; e; e = e->succ_next)
3541 if (e->flags & EDGE_FALLTHRU)
3543 error ("Fallthru edge after a control statement in bb %d \n",
3549 switch (TREE_CODE (stmt))
3555 if (TREE_CODE (COND_EXPR_THEN (stmt)) != GOTO_EXPR
3556 || TREE_CODE (COND_EXPR_ELSE (stmt)) != GOTO_EXPR)
3558 error ("Structured COND_EXPR at the end of bb %d\n", bb->index);
3562 extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
3564 if (!true_edge || !false_edge
3565 || !(true_edge->flags & EDGE_TRUE_VALUE)
3566 || !(false_edge->flags & EDGE_FALSE_VALUE)
3567 || (true_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL))
3568 || (false_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL))
3569 || bb->succ->succ_next->succ_next)
3571 error ("Wrong outgoing edge flags at end of bb %d\n",
3576 if (!has_label_p (true_edge->dest,
3577 GOTO_DESTINATION (COND_EXPR_THEN (stmt))))
3579 error ("`then' label does not match edge at end of bb %d\n",
3584 if (!has_label_p (false_edge->dest,
3585 GOTO_DESTINATION (COND_EXPR_ELSE (stmt))))
3587 error ("`else' label does not match edge at end of bb %d\n",
3595 if (simple_goto_p (stmt))
3597 error ("Explicit goto at end of bb %d\n", bb->index);
3602 /* FIXME. We should double check that the labels in the
3603 destination blocks have their address taken. */
3604 for (e = bb->succ; e; e = e->succ_next)
3605 if ((e->flags & (EDGE_FALLTHRU | EDGE_TRUE_VALUE
3606 | EDGE_FALSE_VALUE))
3607 || !(e->flags & EDGE_ABNORMAL))
3609 error ("Wrong outgoing edge flags at end of bb %d\n",
3617 if (!bb->succ || bb->succ->succ_next
3618 || (bb->succ->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL
3619 | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
3621 error ("Wrong outgoing edge flags at end of bb %d\n", bb->index);
3624 if (bb->succ->dest != EXIT_BLOCK_PTR)
3626 error ("Return edge does not point to exit in bb %d\n",
3639 vec = SWITCH_LABELS (stmt);
3640 n = TREE_VEC_LENGTH (vec);
3642 /* Mark all the destination basic blocks. */
3643 for (i = 0; i < n; ++i)
3645 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
3646 basic_block label_bb = label_to_block (lab);
3648 if (label_bb->aux && label_bb->aux != (void *)1)
3650 label_bb->aux = (void *)1;
3653 /* Verify that the case labels are sorted. */
3654 prev = TREE_VEC_ELT (vec, 0);
3655 for (i = 1; i < n - 1; ++i)
3657 tree c = TREE_VEC_ELT (vec, i);
3660 error ("Found default case not at end of case vector");
3664 if (! tree_int_cst_lt (CASE_LOW (prev), CASE_LOW (c)))
3666 error ("Case labels not sorted:\n ");
3667 print_generic_expr (stderr, prev, 0);
3668 fprintf (stderr," is greater than ");
3669 print_generic_expr (stderr, c, 0);
3670 fprintf (stderr," but comes before it.\n");
3675 if (CASE_LOW (TREE_VEC_ELT (vec, n - 1)))
3677 error ("No default case found at end of case vector");
3681 for (e = bb->succ; e; e = e->succ_next)
3685 error ("Extra outgoing edge %d->%d\n",
3686 bb->index, e->dest->index);
3689 e->dest->aux = (void *)2;
3690 if ((e->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL
3691 | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
3693 error ("Wrong outgoing edge flags at end of bb %d\n",
3699 /* Check that we have all of them. */
3700 for (i = 0; i < n; ++i)
3702 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
3703 basic_block label_bb = label_to_block (lab);
3705 if (label_bb->aux != (void *)2)
3707 error ("Missing edge %i->%i\n",
3708 bb->index, label_bb->index);
3713 for (e = bb->succ; e; e = e->succ_next)
3714 e->dest->aux = (void *)0;
3721 if (dom_computed[CDI_DOMINATORS] >= DOM_NO_FAST_QUERY)
3722 verify_dominators (CDI_DOMINATORS);
3728 /* Updates phi nodes after creating forwarder block joined
3729 by edge FALLTHRU. */
3732 tree_make_forwarder_block (edge fallthru)
3735 basic_block dummy, bb;
3736 tree phi, new_phi, var;
3738 dummy = fallthru->src;
3739 bb = fallthru->dest;
3741 if (!bb->pred->pred_next)
3744 /* If we redirected a branch we must create new phi nodes at the
3746 for (phi = phi_nodes (dummy); phi; phi = TREE_CHAIN (phi))
3748 var = PHI_RESULT (phi);
3749 new_phi = create_phi_node (var, bb);
3750 SSA_NAME_DEF_STMT (var) = new_phi;
3751 PHI_RESULT (phi) = make_ssa_name (SSA_NAME_VAR (var), phi);
3752 add_phi_arg (&new_phi, PHI_RESULT (phi), fallthru);
3755 /* Ensure that the PHI node chains are in the same order. */
3756 set_phi_nodes (bb, nreverse (phi_nodes (bb)));
3758 /* Add the arguments we have stored on edges. */
3759 for (e = bb->pred; e; e = e->pred_next)
3764 for (phi = phi_nodes (bb), var = PENDING_STMT (e);
3766 phi = TREE_CHAIN (phi), var = TREE_CHAIN (var))
3767 add_phi_arg (&phi, TREE_VALUE (var), e);
3769 PENDING_STMT (e) = NULL;
3774 /* Return true if basic block BB does nothing except pass control
3775 flow to another block and that we can safely insert a label at
3776 the start of the successor block. */
3779 tree_forwarder_block_p (basic_block bb)
3781 block_stmt_iterator bsi;
3784 /* If we have already determined that this block is not forwardable,
3785 then no further checks are necessary. */
3786 if (! bb_ann (bb)->forwardable)
3789 /* BB must have a single outgoing normal edge. Otherwise it can not be
3790 a forwarder block. */
3792 || bb->succ->succ_next
3793 || bb->succ->dest == EXIT_BLOCK_PTR
3794 || (bb->succ->flags & EDGE_ABNORMAL)
3795 || bb == ENTRY_BLOCK_PTR)
3797 bb_ann (bb)->forwardable = 0;
3801 /* Successors of the entry block are not forwarders. */
3802 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
3805 bb_ann (bb)->forwardable = 0;
3809 /* BB can not have any PHI nodes. This could potentially be relaxed
3810 early in compilation if we re-rewrote the variables appearing in
3811 any PHI nodes in forwarder blocks. */
3814 bb_ann (bb)->forwardable = 0;
3818 /* Now walk through the statements. We can ignore labels, anything else
3819 means this is not a forwarder block. */
3820 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3822 tree stmt = bsi_stmt (bsi);
3824 switch (TREE_CODE (stmt))
3827 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)))
3832 bb_ann (bb)->forwardable = 0;
3841 /* Thread jumps over empty statements.
3843 This code should _not_ thread over obviously equivalent conditions
3844 as that requires nontrivial updates to the SSA graph. */
3849 edge e, next, last, old;
3850 basic_block bb, dest, tmp;
3853 bool retval = false;
3856 bb_ann (bb)->forwardable = 1;
3858 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb)
3860 /* Don't waste time on unreachable blocks. */
3864 /* Nor on forwarders. */
3865 if (tree_forwarder_block_p (bb))
3868 /* This block is now part of a forwarding path, mark it as not
3869 forwardable so that we can detect loops. This bit will be
3871 bb_ann (bb)->forwardable = 0;
3873 /* Examine each of our block's successors to see if it is
3875 for (e = bb->succ; e; e = next)
3877 next = e->succ_next;
3879 /* If the edge is abnormal or its destination is not
3880 forwardable, then there's nothing to do. */
3881 if ((e->flags & EDGE_ABNORMAL)
3882 || !tree_forwarder_block_p (e->dest))
3885 /* Now walk through as many forwarder block as possible to
3886 find the ultimate destination we want to thread our jump
3888 last = e->dest->succ;
3889 bb_ann (e->dest)->forwardable = 0;
3890 for (dest = e->dest->succ->dest;
3891 tree_forwarder_block_p (dest);
3893 dest = dest->succ->dest)
3895 /* An infinite loop detected. We redirect the edge anyway, so
3896 that the loop is shrinked into single basic block. */
3897 if (!bb_ann (dest)->forwardable)
3900 if (dest->succ->dest == EXIT_BLOCK_PTR)
3903 bb_ann (dest)->forwardable = 0;
3906 /* Reset the forwardable marks to 1. */
3909 tmp = tmp->succ->dest)
3910 bb_ann (tmp)->forwardable = 1;
3912 if (dest == e->dest)
3915 old = find_edge (bb, dest);
3918 /* If there already is an edge, check whether the values
3919 in phi nodes differ. */
3920 if (!phi_alternatives_equal (dest, last, old))
3922 /* The previous block is forwarder. Redirect our jump
3923 to that target instead since we know it has no PHI
3924 nodes that will need updating. */
3927 /* That might mean that no forwarding at all is possible. */
3928 if (dest == e->dest)
3931 old = find_edge (bb, dest);
3935 /* Perform the redirection. */
3937 e = redirect_edge_and_branch (e, dest);
3939 /* TODO -- updating dominators in this case is simple. */
3940 free_dominance_info (CDI_DOMINATORS);
3944 /* Update PHI nodes. We know that the new argument should
3945 have the same value as the argument associated with LAST.
3946 Otherwise we would have changed our target block above. */
3947 for (phi = phi_nodes (dest); phi; phi = TREE_CHAIN (phi))
3949 arg = phi_arg_from_edge (phi, last);
3952 add_phi_arg (&phi, PHI_ARG_DEF (phi, arg), e);
3957 /* Reset the forwardable bit on our block since it's no longer in
3958 a forwarding chain path. */
3959 bb_ann (bb)->forwardable = 1;
3966 /* Return a non-special label in the head of basic block BLOCK.
3967 Create one if it doesn't exist. */
3970 tree_block_label (basic_block bb)
3972 block_stmt_iterator i, s = bsi_start (bb);
3976 for (i = s; !bsi_end_p (i); first = false, bsi_next (&i))
3978 stmt = bsi_stmt (i);
3979 if (TREE_CODE (stmt) != LABEL_EXPR)
3981 label = LABEL_EXPR_LABEL (stmt);
3982 if (!DECL_NONLOCAL (label))
3985 bsi_move_before (&i, &s);
3990 label = create_artificial_label ();
3991 stmt = build1 (LABEL_EXPR, void_type_node, label);
3992 bsi_insert_before (&s, stmt, BSI_NEW_STMT);
3997 /* Attempt to perform edge redirection by replacing a possibly complex
3998 jump instruction by a goto or by removing the jump completely.
3999 This can apply only if all edges now point to the same block. The
4000 parameters and return values are equivalent to
4001 redirect_edge_and_branch. */
4004 tree_try_redirect_by_replacing_jump (edge e, basic_block target)
4006 basic_block src = e->src;
4008 block_stmt_iterator b;
4011 /* Verify that all targets will be TARGET. */
4012 for (tmp = src->succ; tmp; tmp = tmp->succ_next)
4013 if (tmp->dest != target && tmp != e)
4022 stmt = bsi_stmt (b);
4024 if (TREE_CODE (stmt) == COND_EXPR
4025 || TREE_CODE (stmt) == SWITCH_EXPR)
4028 e = ssa_redirect_edge (e, target);
4029 e->flags = EDGE_FALLTHRU;
4037 /* Redirect E to DEST. Return NULL on failure. Otherwise, return the
4038 edge representing the redirected branch. */
4041 tree_redirect_edge_and_branch (edge e, basic_block dest)
4043 basic_block bb = e->src;
4044 block_stmt_iterator bsi;
4048 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
4051 if (e->src != ENTRY_BLOCK_PTR
4052 && (ret = tree_try_redirect_by_replacing_jump (e, dest)))
4055 if (e->dest == dest)
4058 label = tree_block_label (dest);
4060 bsi = bsi_last (bb);
4061 stmt = bsi_end_p (bsi) ? NULL : bsi_stmt (bsi);
4063 switch (stmt ? TREE_CODE (stmt) : ERROR_MARK)
4066 stmt = (e->flags & EDGE_TRUE_VALUE
4067 ? COND_EXPR_THEN (stmt)
4068 : COND_EXPR_ELSE (stmt));
4069 GOTO_DESTINATION (stmt) = label;
4073 /* No non-abnormal edges should lead from a non-simple goto, and
4074 simple ones should be represented implicitly. */
4079 tree vec = SWITCH_LABELS (stmt);
4080 size_t i, n = TREE_VEC_LENGTH (vec);
4082 for (i = 0; i < n; ++i)
4084 tree elt = TREE_VEC_ELT (vec, i);
4085 if (label_to_block (CASE_LABEL (elt)) == e->dest)
4086 CASE_LABEL (elt) = label;
4093 e->flags |= EDGE_FALLTHRU;
4097 /* Otherwise it must be a fallthru edge, and we don't need to
4098 do anything besides redirecting it. */
4099 if (!(e->flags & EDGE_FALLTHRU))
4104 /* Update/insert PHI nodes as necessary. */
4106 /* Now update the edges in the CFG. */
4107 e = ssa_redirect_edge (e, dest);
4113 /* Simple wrapper, as we can always redirect fallthru edges. */
4116 tree_redirect_edge_and_branch_force (edge e, basic_block dest)
4118 e = tree_redirect_edge_and_branch (e, dest);
4126 /* Splits basic block BB after statement STMT (but at least after the
4127 labels). If STMT is NULL, BB is split just after the labels. */
4130 tree_split_block (basic_block bb, void *stmt)
4132 block_stmt_iterator bsi, bsi_tgt;
4137 new_bb = create_empty_bb (bb);
4139 /* Redirect the outgoing edges. */
4140 new_bb->succ = bb->succ;
4142 for (e = new_bb->succ; e; e = e->succ_next)
4145 if (stmt && TREE_CODE ((tree) stmt) == LABEL_EXPR)
4148 /* Move everything from BSI to the new basic block. */
4149 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4151 act = bsi_stmt (bsi);
4152 if (TREE_CODE (act) == LABEL_EXPR)
4165 bsi_tgt = bsi_start (new_bb);
4166 while (!bsi_end_p (bsi))
4168 act = bsi_stmt (bsi);
4170 bsi_insert_after (&bsi_tgt, act, BSI_NEW_STMT);
4177 /* Moves basic block BB after block AFTER. */
4180 tree_move_block_after (basic_block bb, basic_block after)
4182 if (bb->prev_bb == after)
4186 link_block (bb, after);
4192 /* Return true if basic_block can be duplicated. */
4195 tree_can_duplicate_bb_p (basic_block bb ATTRIBUTE_UNUSED)
4201 /* Create a duplicate of the basic block BB. NOTE: This does not
4202 preserve SSA form. */
4205 tree_duplicate_bb (basic_block bb)
4208 block_stmt_iterator bsi, bsi_tgt;
4210 new_bb = create_empty_bb (EXIT_BLOCK_PTR->prev_bb);
4211 bsi_tgt = bsi_start (new_bb);
4212 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4214 tree stmt = bsi_stmt (bsi);
4216 if (TREE_CODE (stmt) == LABEL_EXPR)
4219 bsi_insert_after (&bsi_tgt, unshare_expr (stmt), BSI_NEW_STMT);
4226 /* Dump FUNCTION_DECL FN to file FILE using FLAGS (see TDF_* in tree.h) */
4229 dump_function_to_file (tree fn, FILE *file, int flags)
4231 tree arg, vars, var;
4232 bool ignore_topmost_bind = false, any_var = false;
4236 fprintf (file, "%s (", lang_hooks.decl_printable_name (fn, 2));
4238 arg = DECL_ARGUMENTS (fn);
4241 print_generic_expr (file, arg, dump_flags);
4242 if (TREE_CHAIN (arg))
4243 fprintf (file, ", ");
4244 arg = TREE_CHAIN (arg);
4246 fprintf (file, ")\n");
4248 if (flags & TDF_RAW)
4250 dump_node (fn, TDF_SLIM | flags, file);
4254 /* When GIMPLE is lowered, the variables are no longer available in
4255 BIND_EXPRs, so display them separately. */
4256 if (cfun && cfun->unexpanded_var_list)
4258 ignore_topmost_bind = true;
4260 fprintf (file, "{\n");
4261 for (vars = cfun->unexpanded_var_list; vars; vars = TREE_CHAIN (vars))
4263 var = TREE_VALUE (vars);
4265 print_generic_decl (file, var, flags);
4266 fprintf (file, "\n");
4272 if (basic_block_info)
4274 /* Make a CFG based dump. */
4275 if (!ignore_topmost_bind)
4276 fprintf (file, "{\n");
4278 if (any_var && n_basic_blocks)
4279 fprintf (file, "\n");
4282 dump_generic_bb (file, bb, 2, flags);
4284 fprintf (file, "}\n");
4290 /* Make a tree based dump. */
4291 chain = DECL_SAVED_TREE (fn);
4293 if (TREE_CODE (chain) == BIND_EXPR)
4295 if (ignore_topmost_bind)
4297 chain = BIND_EXPR_BODY (chain);
4305 if (!ignore_topmost_bind)
4306 fprintf (file, "{\n");
4311 fprintf (file, "\n");
4313 print_generic_stmt_indented (file, chain, flags, indent);
4314 if (ignore_topmost_bind)
4315 fprintf (file, "}\n");
4318 fprintf (file, "\n\n");
4322 /* Pretty print of the loops intermediate representation. */
4323 static void print_loop (FILE *, struct loop *, int);
4324 static void print_pred_bbs (FILE *, edge);
4325 static void print_succ_bbs (FILE *, edge);
4328 /* Print the predecessors indexes of edge E on FILE. */
4331 print_pred_bbs (FILE *file, edge e)
4336 else if (e->pred_next == NULL)
4337 fprintf (file, "bb_%d", e->src->index);
4341 fprintf (file, "bb_%d, ", e->src->index);
4342 print_pred_bbs (file, e->pred_next);
4347 /* Print the successors indexes of edge E on FILE. */
4350 print_succ_bbs (FILE *file, edge e)
4354 else if (e->succ_next == NULL)
4355 fprintf (file, "bb_%d", e->dest->index);
4358 fprintf (file, "bb_%d, ", e->dest->index);
4359 print_succ_bbs (file, e->succ_next);
4364 /* Pretty print LOOP on FILE, indented INDENT spaces. */
4367 print_loop (FILE *file, struct loop *loop, int indent)
4375 s_indent = (char *) alloca ((size_t) indent + 1);
4376 memset ((void *) s_indent, ' ', (size_t) indent);
4377 s_indent[indent] = '\0';
4379 /* Print the loop's header. */
4380 fprintf (file, "%sloop_%d\n", s_indent, loop->num);
4382 /* Print the loop's body. */
4383 fprintf (file, "%s{\n", s_indent);
4385 if (bb->loop_father == loop)
4387 /* Print the basic_block's header. */
4388 fprintf (file, "%s bb_%d (preds = {", s_indent, bb->index);
4389 print_pred_bbs (file, bb->pred);
4390 fprintf (file, "}, succs = {");
4391 print_succ_bbs (file, bb->succ);
4392 fprintf (file, "})\n");
4394 /* Print the basic_block's body. */
4395 fprintf (file, "%s {\n", s_indent);
4396 tree_dump_bb (bb, file, indent + 4);
4397 fprintf (file, "%s }\n", s_indent);
4400 print_loop (file, loop->inner, indent + 2);
4401 fprintf (file, "%s}\n", s_indent);
4402 print_loop (file, loop->next, indent);
4406 /* Follow a CFG edge from the entry point of the program, and on entry
4407 of a loop, pretty print the loop structure on FILE. */
4410 print_loop_ir (FILE *file)
4414 bb = BASIC_BLOCK (0);
4415 if (bb && bb->loop_father)
4416 print_loop (file, bb->loop_father, 0);
4420 /* Debugging loops structure at tree level. */
4423 debug_loop_ir (void)
4425 print_loop_ir (stderr);
4429 /* Return true if BB ends with a call, possibly followed by some
4430 instructions that must stay with the call. Return false,
4434 tree_block_ends_with_call_p (basic_block bb)
4436 block_stmt_iterator bsi = bsi_last (bb);
4437 tree t = tsi_stmt (bsi.tsi);
4439 if (TREE_CODE (t) == RETURN_EXPR && TREE_OPERAND (t, 0))
4440 t = TREE_OPERAND (t, 0);
4442 if (TREE_CODE (t) == MODIFY_EXPR)
4443 t = TREE_OPERAND (t, 1);
4445 return TREE_CODE (t) == CALL_EXPR;
4449 /* Return true if BB ends with a conditional branch. Return false,
4453 tree_block_ends_with_condjump_p (basic_block bb)
4455 tree stmt = tsi_stmt (bsi_last (bb).tsi);
4456 return (TREE_CODE (stmt) == COND_EXPR);
4460 /* Return true if we need to add fake edge to exit at statement T.
4461 Helper function for tree_flow_call_edges_add. */
4464 need_fake_edge_p (tree t)
4466 if (TREE_CODE (t) == RETURN_EXPR && TREE_OPERAND (t, 0))
4467 t = TREE_OPERAND (t, 0);
4469 if (TREE_CODE (t) == MODIFY_EXPR)
4470 t = TREE_OPERAND (t, 1);
4472 /* NORETURN and LONGJMP calls already have an edge to exit.
4473 CONST, PURE and ALWAYS_RETURN calls do not need one.
4474 We don't currently check for CONST and PURE here, although
4475 it would be a good idea, because those attributes are
4476 figured out from the RTL in mark_constant_function, and
4477 the counter incrementation code from -fprofile-arcs
4478 leads to different results from -fbranch-probabilities. */
4479 if (TREE_CODE (t) == CALL_EXPR
4480 && !(call_expr_flags (t) &
4481 (ECF_NORETURN | ECF_LONGJMP | ECF_ALWAYS_RETURN)))
4484 if (TREE_CODE (t) == ASM_EXPR
4485 && (ASM_VOLATILE_P (t) || ASM_INPUT_P (t)))
4492 /* Add fake edges to the function exit for any non constant and non
4493 noreturn calls, volatile inline assembly in the bitmap of blocks
4494 specified by BLOCKS or to the whole CFG if BLOCKS is zero. Return
4495 the number of blocks that were split.
4497 The goal is to expose cases in which entering a basic block does
4498 not imply that all subsequent instructions must be executed. */
4501 tree_flow_call_edges_add (sbitmap blocks)
4504 int blocks_split = 0;
4505 int last_bb = last_basic_block;
4506 bool check_last_block = false;
4508 if (n_basic_blocks == 0)
4512 check_last_block = true;
4514 check_last_block = TEST_BIT (blocks, EXIT_BLOCK_PTR->prev_bb->index);
4516 /* In the last basic block, before epilogue generation, there will be
4517 a fallthru edge to EXIT. Special care is required if the last insn
4518 of the last basic block is a call because make_edge folds duplicate
4519 edges, which would result in the fallthru edge also being marked
4520 fake, which would result in the fallthru edge being removed by
4521 remove_fake_edges, which would result in an invalid CFG.
4523 Moreover, we can't elide the outgoing fake edge, since the block
4524 profiler needs to take this into account in order to solve the minimal
4525 spanning tree in the case that the call doesn't return.
4527 Handle this by adding a dummy instruction in a new last basic block. */
4528 if (check_last_block)
4530 basic_block bb = EXIT_BLOCK_PTR->prev_bb;
4531 block_stmt_iterator bsi = bsi_last (bb);
4533 if (!bsi_end_p (bsi))
4536 if (need_fake_edge_p (t))
4540 for (e = bb->succ; e; e = e->succ_next)
4541 if (e->dest == EXIT_BLOCK_PTR)
4543 bsi_insert_on_edge (e, build_empty_stmt ());
4544 bsi_commit_edge_inserts ((int *)NULL);
4550 /* Now add fake edges to the function exit for any non constant
4551 calls since there is no way that we can determine if they will
4553 for (i = 0; i < last_bb; i++)
4555 basic_block bb = BASIC_BLOCK (i);
4556 block_stmt_iterator bsi;
4557 tree stmt, last_stmt;
4562 if (blocks && !TEST_BIT (blocks, i))
4565 bsi = bsi_last (bb);
4566 if (!bsi_end_p (bsi))
4568 last_stmt = bsi_stmt (bsi);
4571 stmt = bsi_stmt (bsi);
4572 if (need_fake_edge_p (stmt))
4575 /* The handling above of the final block before the
4576 epilogue should be enough to verify that there is
4577 no edge to the exit block in CFG already.
4578 Calling make_edge in such case would cause us to
4579 mark that edge as fake and remove it later. */
4580 #ifdef ENABLE_CHECKING
4581 if (stmt == last_stmt)
4582 for (e = bb->succ; e; e = e->succ_next)
4583 if (e->dest == EXIT_BLOCK_PTR)
4587 /* Note that the following may create a new basic block
4588 and renumber the existing basic blocks. */
4589 if (stmt != last_stmt)
4591 e = split_block (bb, stmt);
4595 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
4599 while (!bsi_end_p (bsi));
4604 verify_flow_info ();
4606 return blocks_split;
4610 struct cfg_hooks tree_cfg_hooks = {
4612 tree_verify_flow_info,
4613 tree_dump_bb, /* dump_bb */
4614 create_bb, /* create_basic_block */
4615 tree_redirect_edge_and_branch,/* redirect_edge_and_branch */
4616 tree_redirect_edge_and_branch_force,/* redirect_edge_and_branch_force */
4617 remove_bb, /* delete_basic_block */
4618 tree_split_block, /* split_block */
4619 tree_move_block_after, /* move_block_after */
4620 tree_can_merge_blocks_p, /* can_merge_blocks_p */
4621 tree_merge_blocks, /* merge_blocks */
4622 tree_predict_edge, /* predict_edge */
4623 tree_predicted_by_p, /* predicted_by_p */
4624 tree_can_duplicate_bb_p, /* can_duplicate_block_p */
4625 tree_duplicate_bb, /* duplicate_block */
4626 tree_split_edge, /* split_edge */
4627 tree_make_forwarder_block, /* make_forward_block */
4628 NULL, /* tidy_fallthru_edge */
4629 tree_block_ends_with_call_p, /* block_ends_with_call_p */
4630 tree_block_ends_with_condjump_p, /* block_ends_with_condjump_p */
4631 tree_flow_call_edges_add /* flow_call_edges_add */
4635 /* Split all critical edges. */
4638 split_critical_edges (void)
4645 for (e = bb->succ; e ; e = e->succ_next)
4646 if (EDGE_CRITICAL_P (e) && !(e->flags & EDGE_ABNORMAL))
4653 struct tree_opt_pass pass_split_crit_edges =
4657 split_critical_edges, /* execute */
4660 0, /* static_pass_number */
4661 TV_TREE_SPLIT_EDGES, /* tv_id */
4662 PROP_cfg, /* properties required */
4663 PROP_no_crit_edges, /* properties_provided */
4664 0, /* properties_destroyed */
4665 0, /* todo_flags_start */
4666 0, /* todo_flags_finish */
4669 /* Emit return warnings. */
4672 execute_warn_function_return (void)
4678 if (warn_missing_noreturn
4679 && !TREE_THIS_VOLATILE (cfun->decl)
4680 && EXIT_BLOCK_PTR->pred == NULL
4681 && !lang_hooks.function.missing_noreturn_ok_p (cfun->decl))
4682 warning ("%Jfunction might be possible candidate for attribute `noreturn'",
4685 /* If we have a path to EXIT, then we do return. */
4686 if (TREE_THIS_VOLATILE (cfun->decl)
4687 && EXIT_BLOCK_PTR->pred != NULL)
4690 for (e = EXIT_BLOCK_PTR->pred; e ; e = e->pred_next)
4692 last = last_stmt (e->src);
4693 if (TREE_CODE (last) == RETURN_EXPR
4694 && (locus = EXPR_LOCUS (last)) != NULL)
4698 locus = &cfun->function_end_locus;
4699 warning ("%H`noreturn' function does return", locus);
4702 /* If we see "return;" in some basic block, then we do reach the end
4703 without returning a value. */
4704 else if (warn_return_type
4705 && EXIT_BLOCK_PTR->pred != NULL
4706 && !VOID_TYPE_P (TREE_TYPE (TREE_TYPE (cfun->decl))))
4708 for (e = EXIT_BLOCK_PTR->pred; e ; e = e->pred_next)
4710 tree last = last_stmt (e->src);
4711 if (TREE_CODE (last) == RETURN_EXPR
4712 && TREE_OPERAND (last, 0) == NULL)
4714 locus = EXPR_LOCUS (last);
4716 locus = &cfun->function_end_locus;
4717 warning ("%Hcontrol reaches end of non-void function", locus);
4725 /* Given a basic block B which ends with a conditional and has
4726 precisely two successors, determine which of the edges is taken if
4727 the conditional is true and which is taken if the conditional is
4728 false. Set TRUE_EDGE and FALSE_EDGE appropriately. */
4731 extract_true_false_edges_from_block (basic_block b,
4737 if (e->flags & EDGE_TRUE_VALUE)
4740 *false_edge = e->succ_next;
4745 *true_edge = e->succ_next;
4749 struct tree_opt_pass pass_warn_function_return =
4753 execute_warn_function_return, /* execute */
4756 0, /* static_pass_number */
4758 PROP_ssa, /* properties_required */
4759 0, /* properties_provided */
4760 0, /* properties_destroyed */
4761 0, /* todo_flags_start */
4762 0 /* todo_flags_finish */
4765 #include "gt-tree-cfg.h"