1 /* Control flow functions for trees.
2 Copyright (C) 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
3 Contributed by Diego Novillo <dnovillo@redhat.com>
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 GCC is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to
19 the Free Software Foundation, 59 Temple Place - Suite 330,
20 Boston, MA 02111-1307, USA. */
24 #include "coretypes.h"
29 #include "hard-reg-set.h"
30 #include "basic-block.h"
37 #include "langhooks.h"
38 #include "diagnostic.h"
39 #include "tree-flow.h"
41 #include "tree-dump.h"
42 #include "tree-pass.h"
47 /* This file contains functions for building the Control Flow Graph (CFG)
48 for a function tree. */
50 /* Local declarations. */
52 /* Initial capacity for the basic block array. */
53 static const int initial_cfg_capacity = 20;
55 /* Mapping of labels to their associated blocks. This can greatly speed up
56 building of the CFG in code with lots of gotos. */
57 static GTY(()) varray_type label_to_block_map;
62 long num_merged_labels;
65 static struct cfg_stats_d cfg_stats;
67 /* Nonzero if we found a computed goto while building basic blocks. */
68 static bool found_computed_goto;
70 /* Basic blocks and flowgraphs. */
71 static basic_block create_bb (void *, void *, basic_block);
72 static void create_block_annotation (basic_block);
73 static void free_blocks_annotations (void);
74 static void clear_blocks_annotations (void);
75 static void make_blocks (tree);
76 static void factor_computed_gotos (void);
79 static void make_edges (void);
80 static void make_ctrl_stmt_edges (basic_block);
81 static void make_exit_edges (basic_block);
82 static void make_cond_expr_edges (basic_block);
83 static void make_switch_expr_edges (basic_block);
84 static void make_goto_expr_edges (basic_block);
85 static edge tree_redirect_edge_and_branch (edge, basic_block);
86 static edge tree_try_redirect_by_replacing_jump (edge, basic_block);
87 static void split_critical_edges (void);
89 /* Various helpers. */
90 static inline bool stmt_starts_bb_p (tree, tree);
91 static int tree_verify_flow_info (void);
92 static void tree_make_forwarder_block (edge);
93 static bool thread_jumps (void);
94 static bool tree_forwarder_block_p (basic_block);
95 static void bsi_commit_edge_inserts_1 (edge e);
96 static void tree_cfg2vcg (FILE *);
98 /* Flowgraph optimization and cleanup. */
99 static void tree_merge_blocks (basic_block, basic_block);
100 static bool tree_can_merge_blocks_p (basic_block, basic_block);
101 static void remove_bb (basic_block);
102 static bool cleanup_control_flow (void);
103 static bool cleanup_control_expr_graph (basic_block, block_stmt_iterator);
104 static edge find_taken_edge_cond_expr (basic_block, tree);
105 static edge find_taken_edge_switch_expr (basic_block, tree);
106 static tree find_case_label_for_value (tree, tree);
107 static bool phi_alternatives_equal (basic_block, edge, edge);
110 /*---------------------------------------------------------------------------
112 ---------------------------------------------------------------------------*/
114 /* Entry point to the CFG builder for trees. TP points to the list of
115 statements to be added to the flowgraph. */
118 build_tree_cfg (tree *tp)
120 /* Register specific tree functions. */
121 tree_register_cfg_hooks ();
123 /* Initialize rbi_pool. */
126 /* Initialize the basic block array. */
128 profile_status = PROFILE_ABSENT;
130 last_basic_block = 0;
131 VARRAY_BB_INIT (basic_block_info, initial_cfg_capacity, "basic_block_info");
132 memset ((void *) &cfg_stats, 0, sizeof (cfg_stats));
134 /* Build a mapping of labels to their associated blocks. */
135 VARRAY_BB_INIT (label_to_block_map, initial_cfg_capacity,
136 "label to block map");
138 ENTRY_BLOCK_PTR->next_bb = EXIT_BLOCK_PTR;
139 EXIT_BLOCK_PTR->prev_bb = ENTRY_BLOCK_PTR;
141 found_computed_goto = 0;
144 /* Computed gotos are hell to deal with, especially if there are
145 lots of them with a large number of destinations. So we factor
146 them to a common computed goto location before we build the
147 edge list. After we convert back to normal form, we will un-factor
148 the computed gotos since factoring introduces an unwanted jump. */
149 if (found_computed_goto)
150 factor_computed_gotos ();
152 /* Make sure there is always at least one block, even if its empty. */
153 if (n_basic_blocks == 0)
154 create_empty_bb (ENTRY_BLOCK_PTR);
156 create_block_annotation (ENTRY_BLOCK_PTR);
157 create_block_annotation (EXIT_BLOCK_PTR);
159 /* Adjust the size of the array. */
160 VARRAY_GROW (basic_block_info, n_basic_blocks);
162 /* To speed up statement iterator walks, we first purge dead labels. */
163 cleanup_dead_labels ();
165 /* Group case nodes to reduce the number of edges.
166 We do this after cleaning up dead labels because otherwise we miss
167 a lot of obvious case merging opportunities. */
168 group_case_labels ();
170 /* Create the edges of the flowgraph. */
173 /* Debugging dumps. */
175 /* Write the flowgraph to a VCG file. */
177 int local_dump_flags;
178 FILE *dump_file = dump_begin (TDI_vcg, &local_dump_flags);
181 tree_cfg2vcg (dump_file);
182 dump_end (TDI_vcg, dump_file);
186 /* Dump a textual representation of the flowgraph. */
188 dump_tree_cfg (dump_file, dump_flags);
192 execute_build_cfg (void)
194 build_tree_cfg (&DECL_SAVED_TREE (current_function_decl));
197 struct tree_opt_pass pass_build_cfg =
201 execute_build_cfg, /* execute */
204 0, /* static_pass_number */
205 TV_TREE_CFG, /* tv_id */
206 PROP_gimple_leh, /* properties_required */
207 PROP_cfg, /* properties_provided */
208 0, /* properties_destroyed */
209 0, /* todo_flags_start */
210 TODO_verify_stmts /* todo_flags_finish */
213 /* Search the CFG for any computed gotos. If found, factor them to a
214 common computed goto site. Also record the location of that site so
215 that we can un-factor the gotos after we have converted back to
219 factor_computed_gotos (void)
222 tree factored_label_decl = NULL;
224 tree factored_computed_goto_label = NULL;
225 tree factored_computed_goto = NULL;
227 /* We know there are one or more computed gotos in this function.
228 Examine the last statement in each basic block to see if the block
229 ends with a computed goto. */
233 block_stmt_iterator bsi = bsi_last (bb);
238 last = bsi_stmt (bsi);
240 /* Ignore the computed goto we create when we factor the original
242 if (last == factored_computed_goto)
245 /* If the last statement is a computed goto, factor it. */
246 if (computed_goto_p (last))
250 /* The first time we find a computed goto we need to create
251 the factored goto block and the variable each original
252 computed goto will use for their goto destination. */
253 if (! factored_computed_goto)
255 basic_block new_bb = create_empty_bb (bb);
256 block_stmt_iterator new_bsi = bsi_start (new_bb);
258 /* Create the destination of the factored goto. Each original
259 computed goto will put its desired destination into this
260 variable and jump to the label we create immediately
262 var = create_tmp_var (ptr_type_node, "gotovar");
264 /* Build a label for the new block which will contain the
265 factored computed goto. */
266 factored_label_decl = create_artificial_label ();
267 factored_computed_goto_label
268 = build1 (LABEL_EXPR, void_type_node, factored_label_decl);
269 bsi_insert_after (&new_bsi, factored_computed_goto_label,
272 /* Build our new computed goto. */
273 factored_computed_goto = build1 (GOTO_EXPR, void_type_node, var);
274 bsi_insert_after (&new_bsi, factored_computed_goto,
278 /* Copy the original computed goto's destination into VAR. */
279 assignment = build (MODIFY_EXPR, ptr_type_node,
280 var, GOTO_DESTINATION (last));
281 bsi_insert_before (&bsi, assignment, BSI_SAME_STMT);
283 /* And re-vector the computed goto to the new destination. */
284 GOTO_DESTINATION (last) = factored_label_decl;
290 /* Create annotations for a single basic block. */
293 create_block_annotation (basic_block bb)
295 /* Verify that the tree_annotations field is clear. */
296 if (bb->tree_annotations)
298 bb->tree_annotations = ggc_alloc_cleared (sizeof (struct bb_ann_d));
302 /* Free the annotations for all the basic blocks. */
304 static void free_blocks_annotations (void)
306 clear_blocks_annotations ();
310 /* Clear the annotations for all the basic blocks. */
313 clear_blocks_annotations (void)
317 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb)
318 bb->tree_annotations = NULL;
322 /* Build a flowgraph for the statement_list STMT_LIST. */
325 make_blocks (tree stmt_list)
327 tree_stmt_iterator i = tsi_start (stmt_list);
329 bool start_new_block = true;
330 bool first_stmt_of_list = true;
331 basic_block bb = ENTRY_BLOCK_PTR;
333 while (!tsi_end_p (i))
340 /* If the statement starts a new basic block or if we have determined
341 in a previous pass that we need to create a new block for STMT, do
343 if (start_new_block || stmt_starts_bb_p (stmt, prev_stmt))
345 if (!first_stmt_of_list)
346 stmt_list = tsi_split_statement_list_before (&i);
347 bb = create_basic_block (stmt_list, NULL, bb);
348 start_new_block = false;
351 /* Now add STMT to BB and create the subgraphs for special statement
353 set_bb_for_stmt (stmt, bb);
355 if (computed_goto_p (stmt))
356 found_computed_goto = true;
358 /* If STMT is a basic block terminator, set START_NEW_BLOCK for the
360 if (stmt_ends_bb_p (stmt))
361 start_new_block = true;
364 first_stmt_of_list = false;
369 /* Create and return a new empty basic block after bb AFTER. */
372 create_bb (void *h, void *e, basic_block after)
379 /* Create and initialize a new basic block. */
381 memset (bb, 0, sizeof (*bb));
383 bb->index = last_basic_block;
385 bb->stmt_list = h ? h : alloc_stmt_list ();
387 /* Add the new block to the linked list of blocks. */
388 link_block (bb, after);
390 /* Grow the basic block array if needed. */
391 if ((size_t) last_basic_block == VARRAY_SIZE (basic_block_info))
393 size_t new_size = last_basic_block + (last_basic_block + 3) / 4;
394 VARRAY_GROW (basic_block_info, new_size);
397 /* Add the newly created block to the array. */
398 BASIC_BLOCK (last_basic_block) = bb;
400 create_block_annotation (bb);
405 initialize_bb_rbi (bb);
410 /*---------------------------------------------------------------------------
412 ---------------------------------------------------------------------------*/
414 /* Join all the blocks in the flowgraph. */
421 /* Create an edge from entry to the first block with executable
423 make_edge (ENTRY_BLOCK_PTR, BASIC_BLOCK (0), EDGE_FALLTHRU);
425 /* Traverse basic block array placing edges. */
428 tree first = first_stmt (bb);
429 tree last = last_stmt (bb);
433 /* Edges for statements that always alter flow control. */
434 if (is_ctrl_stmt (last))
435 make_ctrl_stmt_edges (bb);
437 /* Edges for statements that sometimes alter flow control. */
438 if (is_ctrl_altering_stmt (last))
439 make_exit_edges (bb);
442 /* Finally, if no edges were created above, this is a regular
443 basic block that only needs a fallthru edge. */
444 if (bb->succ == NULL)
445 make_edge (bb, bb->next_bb, EDGE_FALLTHRU);
448 /* We do not care about fake edges, so remove any that the CFG
449 builder inserted for completeness. */
450 remove_fake_exit_edges ();
452 /* Clean up the graph and warn for unreachable code. */
457 /* Create edges for control statement at basic block BB. */
460 make_ctrl_stmt_edges (basic_block bb)
462 tree last = last_stmt (bb);
464 #if defined ENABLE_CHECKING
465 if (last == NULL_TREE)
469 switch (TREE_CODE (last))
472 make_goto_expr_edges (bb);
476 make_edge (bb, EXIT_BLOCK_PTR, 0);
480 make_cond_expr_edges (bb);
484 make_switch_expr_edges (bb);
488 make_eh_edges (last);
489 /* Yet another NORETURN hack. */
490 if (bb->succ == NULL)
491 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
500 /* Create exit edges for statements in block BB that alter the flow of
501 control. Statements that alter the control flow are 'goto', 'return'
502 and calls to non-returning functions. */
505 make_exit_edges (basic_block bb)
507 tree last = last_stmt (bb), op;
509 if (last == NULL_TREE)
512 switch (TREE_CODE (last))
515 /* If this function receives a nonlocal goto, then we need to
516 make edges from this call site to all the nonlocal goto
518 if (TREE_SIDE_EFFECTS (last)
519 && current_function_has_nonlocal_label)
520 make_goto_expr_edges (bb);
522 /* If this statement has reachable exception handlers, then
523 create abnormal edges to them. */
524 make_eh_edges (last);
526 /* Some calls are known not to return. For such calls we create
529 We really need to revamp how we build edges so that it's not
530 such a bloody pain to avoid creating edges for this case since
531 all we do is remove these edges when we're done building the
533 if (call_expr_flags (last) & (ECF_NORETURN | ECF_LONGJMP))
535 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
539 /* Don't forget the fall-thru edge. */
540 make_edge (bb, bb->next_bb, EDGE_FALLTHRU);
544 /* A MODIFY_EXPR may have a CALL_EXPR on its RHS and the CALL_EXPR
545 may have an abnormal edge. Search the RHS for this case and
546 create any required edges. */
547 op = get_call_expr_in (last);
548 if (op && TREE_SIDE_EFFECTS (op)
549 && current_function_has_nonlocal_label)
550 make_goto_expr_edges (bb);
552 make_eh_edges (last);
553 make_edge (bb, bb->next_bb, EDGE_FALLTHRU);
562 /* Create the edges for a COND_EXPR starting at block BB.
563 At this point, both clauses must contain only simple gotos. */
566 make_cond_expr_edges (basic_block bb)
568 tree entry = last_stmt (bb);
569 basic_block then_bb, else_bb;
570 tree then_label, else_label;
572 #if defined ENABLE_CHECKING
573 if (entry == NULL_TREE || TREE_CODE (entry) != COND_EXPR)
577 /* Entry basic blocks for each component. */
578 then_label = GOTO_DESTINATION (COND_EXPR_THEN (entry));
579 else_label = GOTO_DESTINATION (COND_EXPR_ELSE (entry));
580 then_bb = label_to_block (then_label);
581 else_bb = label_to_block (else_label);
583 make_edge (bb, then_bb, EDGE_TRUE_VALUE);
584 make_edge (bb, else_bb, EDGE_FALSE_VALUE);
588 /* Create the edges for a SWITCH_EXPR starting at block BB.
589 At this point, the switch body has been lowered and the
590 SWITCH_LABELS filled in, so this is in effect a multi-way branch. */
593 make_switch_expr_edges (basic_block bb)
595 tree entry = last_stmt (bb);
599 vec = SWITCH_LABELS (entry);
600 n = TREE_VEC_LENGTH (vec);
602 for (i = 0; i < n; ++i)
604 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
605 basic_block label_bb = label_to_block (lab);
606 make_edge (bb, label_bb, 0);
611 /* Return the basic block holding label DEST. */
614 label_to_block (tree dest)
616 int uid = LABEL_DECL_UID (dest);
618 /* We would die hard when faced by undefined label. Emit label to
619 very first basic block. This will hopefully make even the dataflow
620 and undefined variable warnings quite right. */
621 if ((errorcount || sorrycount) && uid < 0)
623 block_stmt_iterator bsi = bsi_start (BASIC_BLOCK (0));
626 stmt = build1 (LABEL_EXPR, void_type_node, dest);
627 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
628 uid = LABEL_DECL_UID (dest);
630 return VARRAY_BB (label_to_block_map, uid);
634 /* Create edges for a goto statement at block BB. */
637 make_goto_expr_edges (basic_block bb)
640 basic_block target_bb;
642 block_stmt_iterator last = bsi_last (bb);
644 goto_t = bsi_stmt (last);
646 /* If the last statement is not a GOTO (i.e., it is a RETURN_EXPR,
647 CALL_EXPR or MODIFY_EXPR), then the edge is an abnormal edge resulting
648 from a nonlocal goto. */
649 if (TREE_CODE (goto_t) != GOTO_EXPR)
651 dest = error_mark_node;
656 dest = GOTO_DESTINATION (goto_t);
659 /* A GOTO to a local label creates normal edges. */
660 if (simple_goto_p (goto_t))
662 edge e = make_edge (bb, label_to_block (dest), EDGE_FALLTHRU);
663 #ifdef USE_MAPPED_LOCATION
664 e->goto_locus = EXPR_LOCATION (goto_t);
666 e->goto_locus = EXPR_LOCUS (goto_t);
672 /* Nothing more to do for nonlocal gotos. */
673 if (TREE_CODE (dest) == LABEL_DECL)
676 /* Computed gotos remain. */
679 /* Look for the block starting with the destination label. In the
680 case of a computed goto, make an edge to any label block we find
682 FOR_EACH_BB (target_bb)
684 block_stmt_iterator bsi;
686 for (bsi = bsi_start (target_bb); !bsi_end_p (bsi); bsi_next (&bsi))
688 tree target = bsi_stmt (bsi);
690 if (TREE_CODE (target) != LABEL_EXPR)
694 /* Computed GOTOs. Make an edge to every label block that has
695 been marked as a potential target for a computed goto. */
696 (FORCED_LABEL (LABEL_EXPR_LABEL (target)) && for_call == 0)
697 /* Nonlocal GOTO target. Make an edge to every label block
698 that has been marked as a potential target for a nonlocal
700 || (DECL_NONLOCAL (LABEL_EXPR_LABEL (target)) && for_call == 1))
702 make_edge (bb, target_bb, EDGE_ABNORMAL);
708 /* Degenerate case of computed goto with no labels. */
709 if (!for_call && !bb->succ)
710 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
714 /*---------------------------------------------------------------------------
716 ---------------------------------------------------------------------------*/
718 /* Remove unreachable blocks and other miscellaneous clean up work. */
721 cleanup_tree_cfg (void)
723 bool something_changed = true;
725 timevar_push (TV_TREE_CLEANUP_CFG);
727 /* These three transformations can cascade, so we iterate on them until
729 while (something_changed)
731 something_changed = cleanup_control_flow ();
732 something_changed |= delete_unreachable_blocks ();
733 something_changed |= thread_jumps ();
736 /* Merging the blocks creates no new opportunities for the other
737 optimizations, so do it here. */
742 #ifdef ENABLE_CHECKING
745 timevar_pop (TV_TREE_CLEANUP_CFG);
749 /* Cleanup useless labels in basic blocks. This is something we wish
750 to do early because it allows us to group case labels before creating
751 the edges for the CFG, and it speeds up block statement iterators in
753 We only run this pass once, running it more than once is probably not
756 /* A map from basic block index to the leading label of that block. */
757 static tree *label_for_bb;
759 /* Callback for for_each_eh_region. Helper for cleanup_dead_labels. */
761 update_eh_label (struct eh_region *region)
763 tree old_label = get_eh_region_tree_label (region);
767 basic_block bb = label_to_block (old_label);
769 /* ??? After optimizing, there may be EH regions with labels
770 that have already been removed from the function body, so
771 there is no basic block for them. */
775 new_label = label_for_bb[bb->index];
776 set_eh_region_tree_label (region, new_label);
780 /* Given LABEL return the first label in the same basic block. */
782 main_block_label (tree label)
784 basic_block bb = label_to_block (label);
786 /* label_to_block possibly inserted undefined label into the chain. */
787 if (!label_for_bb[bb->index])
788 label_for_bb[bb->index] = label;
789 return label_for_bb[bb->index];
792 /* Cleanup redundant labels. This is a three-steo process:
793 1) Find the leading label for each block.
794 2) Redirect all references to labels to the leading labels.
795 3) Cleanup all useless labels. */
798 cleanup_dead_labels (void)
801 label_for_bb = xcalloc (last_basic_block, sizeof (tree));
803 /* Find a suitable label for each block. We use the first user-defined
804 label is there is one, or otherwise just the first label we see. */
807 block_stmt_iterator i;
809 for (i = bsi_start (bb); !bsi_end_p (i); bsi_next (&i))
811 tree label, stmt = bsi_stmt (i);
813 if (TREE_CODE (stmt) != LABEL_EXPR)
816 label = LABEL_EXPR_LABEL (stmt);
818 /* If we have not yet seen a label for the current block,
819 remember this one and see if there are more labels. */
820 if (! label_for_bb[bb->index])
822 label_for_bb[bb->index] = label;
826 /* If we did see a label for the current block already, but it
827 is an artificially created label, replace it if the current
828 label is a user defined label. */
829 if (! DECL_ARTIFICIAL (label)
830 && DECL_ARTIFICIAL (label_for_bb[bb->index]))
832 label_for_bb[bb->index] = label;
838 /* Now redirect all jumps/branches to the selected label.
839 First do so for each block ending in a control statement. */
842 tree stmt = last_stmt (bb);
846 switch (TREE_CODE (stmt))
850 tree true_branch, false_branch;
852 true_branch = COND_EXPR_THEN (stmt);
853 false_branch = COND_EXPR_ELSE (stmt);
855 GOTO_DESTINATION (true_branch)
856 = main_block_label (GOTO_DESTINATION (true_branch));
857 GOTO_DESTINATION (false_branch)
858 = main_block_label (GOTO_DESTINATION (false_branch));
866 tree vec = SWITCH_LABELS (stmt);
867 size_t n = TREE_VEC_LENGTH (vec);
869 /* Replace all destination labels. */
870 for (i = 0; i < n; ++i)
871 CASE_LABEL (TREE_VEC_ELT (vec, i))
872 = main_block_label (CASE_LABEL (TREE_VEC_ELT (vec, i)));
877 /* We have to handle GOTO_EXPRs until they're removed, and we don't
878 remove them until after we've created the CFG edges. */
880 if (! computed_goto_p (stmt))
882 GOTO_DESTINATION (stmt)
883 = main_block_label (GOTO_DESTINATION (stmt));
892 for_each_eh_region (update_eh_label);
894 /* Finally, purge dead labels. All user-defined labels and labels that
895 can be the target of non-local gotos are preserved. */
898 block_stmt_iterator i;
899 tree label_for_this_bb = label_for_bb[bb->index];
901 if (! label_for_this_bb)
904 for (i = bsi_start (bb); !bsi_end_p (i); )
906 tree label, stmt = bsi_stmt (i);
908 if (TREE_CODE (stmt) != LABEL_EXPR)
911 label = LABEL_EXPR_LABEL (stmt);
913 if (label == label_for_this_bb
914 || ! DECL_ARTIFICIAL (label)
915 || DECL_NONLOCAL (label))
925 /* Look for blocks ending in a multiway branch (a SWITCH_EXPR in GIMPLE),
926 and scan the sorted vector of cases. Combine the ones jumping to the
928 Eg. three separate entries 1: 2: 3: become one entry 1..3: */
931 group_case_labels (void)
937 tree stmt = last_stmt (bb);
938 if (stmt && TREE_CODE (stmt) == SWITCH_EXPR)
940 tree labels = SWITCH_LABELS (stmt);
941 int old_size = TREE_VEC_LENGTH (labels);
942 int i, j, new_size = old_size;
943 tree default_label = TREE_VEC_ELT (labels, old_size - 1);
945 /* Look for possible opportunities to merge cases.
946 Ignore the last element of the label vector because it
947 must be the default case. */
949 while (i < old_size - 2)
951 tree base_case, base_label, base_high, type;
952 base_case = TREE_VEC_ELT (labels, i);
957 base_label = CASE_LABEL (base_case);
959 /* Discard cases that have the same destination as the
961 if (base_label == default_label)
963 TREE_VEC_ELT (labels, i) = NULL_TREE;
968 type = TREE_TYPE (CASE_LOW (base_case));
969 base_high = CASE_HIGH (base_case) ?
970 CASE_HIGH (base_case) : CASE_LOW (base_case);
972 /* Try to merge case labels. Break out when we reach the end
973 of the label vector or when we cannot merge the next case
974 label with the current one. */
975 while (i < old_size - 2)
977 tree merge_case = TREE_VEC_ELT (labels, ++i);
978 tree merge_label = CASE_LABEL (merge_case);
979 tree t = int_const_binop (PLUS_EXPR, base_high,
980 integer_one_node, 1);
982 /* Merge the cases if they jump to the same place,
983 and their ranges are consecutive. */
984 if (merge_label == base_label
985 && tree_int_cst_equal (CASE_LOW (merge_case), t))
987 base_high = CASE_HIGH (merge_case) ?
988 CASE_HIGH (merge_case) : CASE_LOW (merge_case);
989 CASE_HIGH (base_case) = base_high;
990 TREE_VEC_ELT (labels, i) = NULL_TREE;
998 /* Compress the case labels in the label vector, and adjust the
999 length of the vector. */
1000 for (i = 0, j = 0; i < new_size; i++)
1002 while (! TREE_VEC_ELT (labels, j))
1004 TREE_VEC_ELT (labels, i) = TREE_VEC_ELT (labels, j++);
1006 TREE_VEC_LENGTH (labels) = new_size;
1011 /* Checks whether we can merge block B into block A. */
1014 tree_can_merge_blocks_p (basic_block a, basic_block b)
1017 block_stmt_iterator bsi;
1020 || a->succ->succ_next)
1023 if (a->succ->flags & EDGE_ABNORMAL)
1026 if (a->succ->dest != b)
1029 if (b == EXIT_BLOCK_PTR)
1032 if (b->pred->pred_next)
1035 /* If A ends by a statement causing exceptions or something similar, we
1036 cannot merge the blocks. */
1037 stmt = last_stmt (a);
1038 if (stmt && stmt_ends_bb_p (stmt))
1041 /* Do not allow a block with only a non-local label to be merged. */
1042 if (stmt && TREE_CODE (stmt) == LABEL_EXPR
1043 && DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)))
1046 /* There may be no phi nodes at the start of b. Most of these degenerate
1047 phi nodes should be cleaned up by kill_redundant_phi_nodes. */
1051 /* Do not remove user labels. */
1052 for (bsi = bsi_start (b); !bsi_end_p (bsi); bsi_next (&bsi))
1054 stmt = bsi_stmt (bsi);
1055 if (TREE_CODE (stmt) != LABEL_EXPR)
1057 if (!DECL_ARTIFICIAL (LABEL_EXPR_LABEL (stmt)))
1065 /* Merge block B into block A. */
1068 tree_merge_blocks (basic_block a, basic_block b)
1070 block_stmt_iterator bsi;
1071 tree_stmt_iterator last;
1074 fprintf (dump_file, "Merging blocks %d and %d\n", a->index, b->index);
1076 /* Ensure that B follows A. */
1077 move_block_after (b, a);
1079 if (!(a->succ->flags & EDGE_FALLTHRU))
1083 && stmt_ends_bb_p (last_stmt (a)))
1086 /* Remove labels from B and set bb_for_stmt to A for other statements. */
1087 for (bsi = bsi_start (b); !bsi_end_p (bsi);)
1089 if (TREE_CODE (bsi_stmt (bsi)) == LABEL_EXPR)
1093 set_bb_for_stmt (bsi_stmt (bsi), a);
1098 /* Merge the chains. */
1099 last = tsi_last (a->stmt_list);
1100 tsi_link_after (&last, b->stmt_list, TSI_NEW_STMT);
1101 b->stmt_list = NULL;
1105 /* Walk the function tree removing unnecessary statements.
1107 * Empty statement nodes are removed
1109 * Unnecessary TRY_FINALLY and TRY_CATCH blocks are removed
1111 * Unnecessary COND_EXPRs are removed
1113 * Some unnecessary BIND_EXPRs are removed
1115 Clearly more work could be done. The trick is doing the analysis
1116 and removal fast enough to be a net improvement in compile times.
1118 Note that when we remove a control structure such as a COND_EXPR
1119 BIND_EXPR, or TRY block, we will need to repeat this optimization pass
1120 to ensure we eliminate all the useless code. */
1131 static void remove_useless_stmts_1 (tree *, struct rus_data *);
1134 remove_useless_stmts_warn_notreached (tree stmt)
1136 if (EXPR_HAS_LOCATION (stmt))
1138 location_t loc = EXPR_LOCATION (stmt);
1139 warning ("%Hwill never be executed", &loc);
1143 switch (TREE_CODE (stmt))
1145 case STATEMENT_LIST:
1147 tree_stmt_iterator i;
1148 for (i = tsi_start (stmt); !tsi_end_p (i); tsi_next (&i))
1149 if (remove_useless_stmts_warn_notreached (tsi_stmt (i)))
1155 if (remove_useless_stmts_warn_notreached (COND_EXPR_COND (stmt)))
1157 if (remove_useless_stmts_warn_notreached (COND_EXPR_THEN (stmt)))
1159 if (remove_useless_stmts_warn_notreached (COND_EXPR_ELSE (stmt)))
1163 case TRY_FINALLY_EXPR:
1164 case TRY_CATCH_EXPR:
1165 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt, 0)))
1167 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt, 1)))
1172 return remove_useless_stmts_warn_notreached (CATCH_BODY (stmt));
1173 case EH_FILTER_EXPR:
1174 return remove_useless_stmts_warn_notreached (EH_FILTER_FAILURE (stmt));
1176 return remove_useless_stmts_warn_notreached (BIND_EXPR_BLOCK (stmt));
1179 /* Not a live container. */
1187 remove_useless_stmts_cond (tree *stmt_p, struct rus_data *data)
1189 tree then_clause, else_clause, cond;
1190 bool save_has_label, then_has_label, else_has_label;
1192 save_has_label = data->has_label;
1193 data->has_label = false;
1194 data->last_goto = NULL;
1196 remove_useless_stmts_1 (&COND_EXPR_THEN (*stmt_p), data);
1198 then_has_label = data->has_label;
1199 data->has_label = false;
1200 data->last_goto = NULL;
1202 remove_useless_stmts_1 (&COND_EXPR_ELSE (*stmt_p), data);
1204 else_has_label = data->has_label;
1205 data->has_label = save_has_label | then_has_label | else_has_label;
1208 then_clause = COND_EXPR_THEN (*stmt_p);
1209 else_clause = COND_EXPR_ELSE (*stmt_p);
1210 cond = COND_EXPR_COND (*stmt_p);
1212 /* If neither arm does anything at all, we can remove the whole IF. */
1213 if (!TREE_SIDE_EFFECTS (then_clause) && !TREE_SIDE_EFFECTS (else_clause))
1215 *stmt_p = build_empty_stmt ();
1216 data->repeat = true;
1219 /* If there are no reachable statements in an arm, then we can
1220 zap the entire conditional. */
1221 else if (integer_nonzerop (cond) && !else_has_label)
1223 if (warn_notreached)
1224 remove_useless_stmts_warn_notreached (else_clause);
1225 *stmt_p = then_clause;
1226 data->repeat = true;
1228 else if (integer_zerop (cond) && !then_has_label)
1230 if (warn_notreached)
1231 remove_useless_stmts_warn_notreached (then_clause);
1232 *stmt_p = else_clause;
1233 data->repeat = true;
1236 /* Check a couple of simple things on then/else with single stmts. */
1239 tree then_stmt = expr_only (then_clause);
1240 tree else_stmt = expr_only (else_clause);
1242 /* Notice branches to a common destination. */
1243 if (then_stmt && else_stmt
1244 && TREE_CODE (then_stmt) == GOTO_EXPR
1245 && TREE_CODE (else_stmt) == GOTO_EXPR
1246 && (GOTO_DESTINATION (then_stmt) == GOTO_DESTINATION (else_stmt)))
1248 *stmt_p = then_stmt;
1249 data->repeat = true;
1252 /* If the THEN/ELSE clause merely assigns a value to a variable or
1253 parameter which is already known to contain that value, then
1254 remove the useless THEN/ELSE clause. */
1255 else if (TREE_CODE (cond) == VAR_DECL || TREE_CODE (cond) == PARM_DECL)
1258 && TREE_CODE (else_stmt) == MODIFY_EXPR
1259 && TREE_OPERAND (else_stmt, 0) == cond
1260 && integer_zerop (TREE_OPERAND (else_stmt, 1)))
1261 COND_EXPR_ELSE (*stmt_p) = alloc_stmt_list ();
1263 else if ((TREE_CODE (cond) == EQ_EXPR || TREE_CODE (cond) == NE_EXPR)
1264 && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL
1265 || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL)
1266 && TREE_CONSTANT (TREE_OPERAND (cond, 1)))
1268 tree stmt = (TREE_CODE (cond) == EQ_EXPR
1269 ? then_stmt : else_stmt);
1270 tree *location = (TREE_CODE (cond) == EQ_EXPR
1271 ? &COND_EXPR_THEN (*stmt_p)
1272 : &COND_EXPR_ELSE (*stmt_p));
1275 && TREE_CODE (stmt) == MODIFY_EXPR
1276 && TREE_OPERAND (stmt, 0) == TREE_OPERAND (cond, 0)
1277 && TREE_OPERAND (stmt, 1) == TREE_OPERAND (cond, 1))
1278 *location = alloc_stmt_list ();
1282 /* Protect GOTOs in the arm of COND_EXPRs from being removed. They
1283 would be re-introduced during lowering. */
1284 data->last_goto = NULL;
1289 remove_useless_stmts_tf (tree *stmt_p, struct rus_data *data)
1291 bool save_may_branch, save_may_throw;
1292 bool this_may_branch, this_may_throw;
1294 /* Collect may_branch and may_throw information for the body only. */
1295 save_may_branch = data->may_branch;
1296 save_may_throw = data->may_throw;
1297 data->may_branch = false;
1298 data->may_throw = false;
1299 data->last_goto = NULL;
1301 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 0), data);
1303 this_may_branch = data->may_branch;
1304 this_may_throw = data->may_throw;
1305 data->may_branch |= save_may_branch;
1306 data->may_throw |= save_may_throw;
1307 data->last_goto = NULL;
1309 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 1), data);
1311 /* If the body is empty, then we can emit the FINALLY block without
1312 the enclosing TRY_FINALLY_EXPR. */
1313 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 0)))
1315 *stmt_p = TREE_OPERAND (*stmt_p, 1);
1316 data->repeat = true;
1319 /* If the handler is empty, then we can emit the TRY block without
1320 the enclosing TRY_FINALLY_EXPR. */
1321 else if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 1)))
1323 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1324 data->repeat = true;
1327 /* If the body neither throws, nor branches, then we can safely
1328 string the TRY and FINALLY blocks together. */
1329 else if (!this_may_branch && !this_may_throw)
1331 tree stmt = *stmt_p;
1332 *stmt_p = TREE_OPERAND (stmt, 0);
1333 append_to_statement_list (TREE_OPERAND (stmt, 1), stmt_p);
1334 data->repeat = true;
1340 remove_useless_stmts_tc (tree *stmt_p, struct rus_data *data)
1342 bool save_may_throw, this_may_throw;
1343 tree_stmt_iterator i;
1346 /* Collect may_throw information for the body only. */
1347 save_may_throw = data->may_throw;
1348 data->may_throw = false;
1349 data->last_goto = NULL;
1351 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 0), data);
1353 this_may_throw = data->may_throw;
1354 data->may_throw = save_may_throw;
1356 /* If the body cannot throw, then we can drop the entire TRY_CATCH_EXPR. */
1357 if (!this_may_throw)
1359 if (warn_notreached)
1360 remove_useless_stmts_warn_notreached (TREE_OPERAND (*stmt_p, 1));
1361 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1362 data->repeat = true;
1366 /* Process the catch clause specially. We may be able to tell that
1367 no exceptions propagate past this point. */
1369 this_may_throw = true;
1370 i = tsi_start (TREE_OPERAND (*stmt_p, 1));
1371 stmt = tsi_stmt (i);
1372 data->last_goto = NULL;
1374 switch (TREE_CODE (stmt))
1377 for (; !tsi_end_p (i); tsi_next (&i))
1379 stmt = tsi_stmt (i);
1380 /* If we catch all exceptions, then the body does not
1381 propagate exceptions past this point. */
1382 if (CATCH_TYPES (stmt) == NULL)
1383 this_may_throw = false;
1384 data->last_goto = NULL;
1385 remove_useless_stmts_1 (&CATCH_BODY (stmt), data);
1389 case EH_FILTER_EXPR:
1390 if (EH_FILTER_MUST_NOT_THROW (stmt))
1391 this_may_throw = false;
1392 else if (EH_FILTER_TYPES (stmt) == NULL)
1393 this_may_throw = false;
1394 remove_useless_stmts_1 (&EH_FILTER_FAILURE (stmt), data);
1398 /* Otherwise this is a cleanup. */
1399 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 1), data);
1401 /* If the cleanup is empty, then we can emit the TRY block without
1402 the enclosing TRY_CATCH_EXPR. */
1403 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 1)))
1405 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1406 data->repeat = true;
1410 data->may_throw |= this_may_throw;
1415 remove_useless_stmts_bind (tree *stmt_p, struct rus_data *data)
1419 /* First remove anything underneath the BIND_EXPR. */
1420 remove_useless_stmts_1 (&BIND_EXPR_BODY (*stmt_p), data);
1422 /* If the BIND_EXPR has no variables, then we can pull everything
1423 up one level and remove the BIND_EXPR, unless this is the toplevel
1424 BIND_EXPR for the current function or an inlined function.
1426 When this situation occurs we will want to apply this
1427 optimization again. */
1428 block = BIND_EXPR_BLOCK (*stmt_p);
1429 if (BIND_EXPR_VARS (*stmt_p) == NULL_TREE
1430 && *stmt_p != DECL_SAVED_TREE (current_function_decl)
1432 || ! BLOCK_ABSTRACT_ORIGIN (block)
1433 || (TREE_CODE (BLOCK_ABSTRACT_ORIGIN (block))
1436 *stmt_p = BIND_EXPR_BODY (*stmt_p);
1437 data->repeat = true;
1443 remove_useless_stmts_goto (tree *stmt_p, struct rus_data *data)
1445 tree dest = GOTO_DESTINATION (*stmt_p);
1447 data->may_branch = true;
1448 data->last_goto = NULL;
1450 /* Record the last goto expr, so that we can delete it if unnecessary. */
1451 if (TREE_CODE (dest) == LABEL_DECL)
1452 data->last_goto = stmt_p;
1457 remove_useless_stmts_label (tree *stmt_p, struct rus_data *data)
1459 tree label = LABEL_EXPR_LABEL (*stmt_p);
1461 data->has_label = true;
1463 /* We do want to jump across non-local label receiver code. */
1464 if (DECL_NONLOCAL (label))
1465 data->last_goto = NULL;
1467 else if (data->last_goto && GOTO_DESTINATION (*data->last_goto) == label)
1469 *data->last_goto = build_empty_stmt ();
1470 data->repeat = true;
1473 /* ??? Add something here to delete unused labels. */
1477 /* If the function is "const" or "pure", then clear TREE_SIDE_EFFECTS on its
1478 decl. This allows us to eliminate redundant or useless
1479 calls to "const" functions.
1481 Gimplifier already does the same operation, but we may notice functions
1482 being const and pure once their calls has been gimplified, so we need
1483 to update the flag. */
1486 update_call_expr_flags (tree call)
1488 tree decl = get_callee_fndecl (call);
1491 if (call_expr_flags (call) & (ECF_CONST | ECF_PURE))
1492 TREE_SIDE_EFFECTS (call) = 0;
1493 if (TREE_NOTHROW (decl))
1494 TREE_NOTHROW (call) = 1;
1498 /* T is CALL_EXPR. Set current_function_calls_* flags. */
1501 notice_special_calls (tree t)
1503 int flags = call_expr_flags (t);
1505 if (flags & ECF_MAY_BE_ALLOCA)
1506 current_function_calls_alloca = true;
1507 if (flags & ECF_RETURNS_TWICE)
1508 current_function_calls_setjmp = true;
1512 /* Clear flags set by notice_special_calls. Used by dead code removal
1513 to update the flags. */
1516 clear_special_calls (void)
1518 current_function_calls_alloca = false;
1519 current_function_calls_setjmp = false;
1524 remove_useless_stmts_1 (tree *tp, struct rus_data *data)
1528 switch (TREE_CODE (t))
1531 remove_useless_stmts_cond (tp, data);
1534 case TRY_FINALLY_EXPR:
1535 remove_useless_stmts_tf (tp, data);
1538 case TRY_CATCH_EXPR:
1539 remove_useless_stmts_tc (tp, data);
1543 remove_useless_stmts_bind (tp, data);
1547 remove_useless_stmts_goto (tp, data);
1551 remove_useless_stmts_label (tp, data);
1556 data->last_goto = NULL;
1557 data->may_branch = true;
1562 data->last_goto = NULL;
1563 notice_special_calls (t);
1564 update_call_expr_flags (t);
1565 if (tree_could_throw_p (t))
1566 data->may_throw = true;
1570 data->last_goto = NULL;
1572 op = get_call_expr_in (t);
1575 update_call_expr_flags (op);
1576 notice_special_calls (op);
1578 if (tree_could_throw_p (t))
1579 data->may_throw = true;
1582 case STATEMENT_LIST:
1584 tree_stmt_iterator i = tsi_start (t);
1585 while (!tsi_end_p (i))
1588 if (IS_EMPTY_STMT (t))
1594 remove_useless_stmts_1 (tsi_stmt_ptr (i), data);
1597 if (TREE_CODE (t) == STATEMENT_LIST)
1599 tsi_link_before (&i, t, TSI_SAME_STMT);
1609 data->last_goto = NULL;
1613 data->last_goto = NULL;
1619 remove_useless_stmts (void)
1621 struct rus_data data;
1623 clear_special_calls ();
1627 memset (&data, 0, sizeof (data));
1628 remove_useless_stmts_1 (&DECL_SAVED_TREE (current_function_decl), &data);
1630 while (data.repeat);
1634 struct tree_opt_pass pass_remove_useless_stmts =
1636 "useless", /* name */
1638 remove_useless_stmts, /* execute */
1641 0, /* static_pass_number */
1643 PROP_gimple_any, /* properties_required */
1644 0, /* properties_provided */
1645 0, /* properties_destroyed */
1646 0, /* todo_flags_start */
1647 TODO_dump_func /* todo_flags_finish */
1651 /* Remove obviously useless statements in basic block BB. */
1654 cfg_remove_useless_stmts_bb (basic_block bb)
1656 block_stmt_iterator bsi;
1657 tree stmt = NULL_TREE;
1658 tree cond, var = NULL_TREE, val = NULL_TREE;
1659 struct var_ann_d *ann;
1661 /* Check whether we come here from a condition, and if so, get the
1664 || bb->pred->pred_next
1665 || !(bb->pred->flags & (EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
1668 cond = COND_EXPR_COND (last_stmt (bb->pred->src));
1670 if (TREE_CODE (cond) == VAR_DECL || TREE_CODE (cond) == PARM_DECL)
1673 val = (bb->pred->flags & EDGE_FALSE_VALUE
1674 ? boolean_false_node : boolean_true_node);
1676 else if (TREE_CODE (cond) == TRUTH_NOT_EXPR
1677 && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL
1678 || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL))
1680 var = TREE_OPERAND (cond, 0);
1681 val = (bb->pred->flags & EDGE_FALSE_VALUE
1682 ? boolean_true_node : boolean_false_node);
1686 if (bb->pred->flags & EDGE_FALSE_VALUE)
1687 cond = invert_truthvalue (cond);
1688 if (TREE_CODE (cond) == EQ_EXPR
1689 && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL
1690 || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL)
1691 && (TREE_CODE (TREE_OPERAND (cond, 1)) == VAR_DECL
1692 || TREE_CODE (TREE_OPERAND (cond, 1)) == PARM_DECL
1693 || TREE_CONSTANT (TREE_OPERAND (cond, 1))))
1695 var = TREE_OPERAND (cond, 0);
1696 val = TREE_OPERAND (cond, 1);
1702 /* Only work for normal local variables. */
1703 ann = var_ann (var);
1706 || TREE_ADDRESSABLE (var))
1709 if (! TREE_CONSTANT (val))
1711 ann = var_ann (val);
1714 || TREE_ADDRESSABLE (val))
1718 /* Ignore floating point variables, since comparison behaves weird for
1720 if (FLOAT_TYPE_P (TREE_TYPE (var)))
1723 for (bsi = bsi_start (bb); !bsi_end_p (bsi);)
1725 stmt = bsi_stmt (bsi);
1727 /* If the THEN/ELSE clause merely assigns a value to a variable/parameter
1728 which is already known to contain that value, then remove the useless
1729 THEN/ELSE clause. */
1730 if (TREE_CODE (stmt) == MODIFY_EXPR
1731 && TREE_OPERAND (stmt, 0) == var
1732 && operand_equal_p (val, TREE_OPERAND (stmt, 1), 0))
1738 /* Invalidate the var if we encounter something that could modify it. */
1739 if (TREE_CODE (stmt) == ASM_EXPR
1740 || (TREE_CODE (stmt) == MODIFY_EXPR
1741 && TREE_OPERAND (stmt, 0) == var))
1749 /* A CFG-aware version of remove_useless_stmts. */
1752 cfg_remove_useless_stmts (void)
1756 #ifdef ENABLE_CHECKING
1757 verify_flow_info ();
1762 cfg_remove_useless_stmts_bb (bb);
1767 /* Remove PHI nodes associated with basic block BB and all edges out of BB. */
1770 remove_phi_nodes_and_edges_for_unreachable_block (basic_block bb)
1774 /* Since this block is no longer reachable, we can just delete all
1775 of its PHI nodes. */
1776 phi = phi_nodes (bb);
1779 tree next = PHI_CHAIN (phi);
1780 remove_phi_node (phi, NULL_TREE, bb);
1784 /* Remove edges to BB's successors. */
1785 while (bb->succ != NULL)
1786 ssa_remove_edge (bb->succ);
1790 /* Remove statements of basic block BB. */
1793 remove_bb (basic_block bb)
1795 block_stmt_iterator i;
1796 source_locus loc = 0;
1800 fprintf (dump_file, "Removing basic block %d\n", bb->index);
1801 if (dump_flags & TDF_DETAILS)
1803 dump_bb (bb, dump_file, 0);
1804 fprintf (dump_file, "\n");
1808 /* Remove all the instructions in the block. */
1809 for (i = bsi_start (bb); !bsi_end_p (i); bsi_remove (&i))
1811 tree stmt = bsi_stmt (i);
1813 set_bb_for_stmt (stmt, NULL);
1815 /* Don't warn for removed gotos. Gotos are often removed due to
1816 jump threading, thus resulting in bogus warnings. Not great,
1817 since this way we lose warnings for gotos in the original
1818 program that are indeed unreachable. */
1819 if (TREE_CODE (stmt) != GOTO_EXPR && EXPR_HAS_LOCATION (stmt) && !loc)
1820 #ifdef USE_MAPPED_LOCATION
1821 loc = EXPR_LOCATION (stmt);
1823 loc = EXPR_LOCUS (stmt);
1827 /* If requested, give a warning that the first statement in the
1828 block is unreachable. We walk statements backwards in the
1829 loop above, so the last statement we process is the first statement
1831 if (warn_notreached && loc)
1832 #ifdef USE_MAPPED_LOCATION
1833 warning ("%Hwill never be executed", &loc);
1835 warning ("%Hwill never be executed", loc);
1838 remove_phi_nodes_and_edges_for_unreachable_block (bb);
1842 /* Examine BB to determine if it is a forwarding block (a block which only
1843 transfers control to a new destination). If BB is a forwarding block,
1844 then return the edge leading to the ultimate destination. */
1847 tree_block_forwards_to (basic_block bb)
1849 block_stmt_iterator bsi;
1850 bb_ann_t ann = bb_ann (bb);
1853 /* If this block is not forwardable, then avoid useless work. */
1854 if (! ann->forwardable)
1857 /* Set this block to not be forwardable. This prevents infinite loops since
1858 any block currently under examination is considered non-forwardable. */
1859 ann->forwardable = 0;
1861 /* No forwarding is possible if this block is a special block (ENTRY/EXIT),
1862 this block has more than one successor, this block's single successor is
1863 reached via an abnormal edge, this block has phi nodes, or this block's
1864 single successor has phi nodes. */
1865 if (bb == EXIT_BLOCK_PTR
1866 || bb == ENTRY_BLOCK_PTR
1868 || bb->succ->succ_next
1869 || bb->succ->dest == EXIT_BLOCK_PTR
1870 || (bb->succ->flags & EDGE_ABNORMAL) != 0
1872 || phi_nodes (bb->succ->dest))
1875 /* Walk past any labels at the start of this block. */
1876 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
1878 stmt = bsi_stmt (bsi);
1879 if (TREE_CODE (stmt) != LABEL_EXPR)
1883 /* If we reached the end of this block we may be able to optimize this
1885 if (bsi_end_p (bsi))
1889 /* Recursive call to pick up chains of forwarding blocks. */
1890 dest = tree_block_forwards_to (bb->succ->dest);
1892 /* If none found, we forward to bb->succ at minimum. */
1896 ann->forwardable = 1;
1900 /* No forwarding possible. */
1905 /* Try to remove superfluous control structures. */
1908 cleanup_control_flow (void)
1911 block_stmt_iterator bsi;
1912 bool retval = false;
1917 bsi = bsi_last (bb);
1919 if (bsi_end_p (bsi))
1922 stmt = bsi_stmt (bsi);
1923 if (TREE_CODE (stmt) == COND_EXPR
1924 || TREE_CODE (stmt) == SWITCH_EXPR)
1925 retval |= cleanup_control_expr_graph (bb, bsi);
1931 /* Disconnect an unreachable block in the control expression starting
1935 cleanup_control_expr_graph (basic_block bb, block_stmt_iterator bsi)
1938 bool retval = false;
1939 tree expr = bsi_stmt (bsi), val;
1941 if (bb->succ->succ_next)
1945 switch (TREE_CODE (expr))
1948 val = COND_EXPR_COND (expr);
1952 val = SWITCH_COND (expr);
1953 if (TREE_CODE (val) != INTEGER_CST)
1961 taken_edge = find_taken_edge (bb, val);
1965 /* Remove all the edges except the one that is always executed. */
1966 for (e = bb->succ; e; e = next)
1968 next = e->succ_next;
1969 if (e != taken_edge)
1971 taken_edge->probability += e->probability;
1972 taken_edge->count += e->count;
1973 ssa_remove_edge (e);
1977 if (taken_edge->probability > REG_BR_PROB_BASE)
1978 taken_edge->probability = REG_BR_PROB_BASE;
1981 taken_edge = bb->succ;
1984 taken_edge->flags = EDGE_FALLTHRU;
1986 /* We removed some paths from the cfg. */
1987 if (dom_computed[CDI_DOMINATORS] >= DOM_CONS_OK)
1988 dom_computed[CDI_DOMINATORS] = DOM_CONS_OK;
1994 /* Given a control block BB and a predicate VAL, return the edge that
1995 will be taken out of the block. If VAL does not match a unique
1996 edge, NULL is returned. */
1999 find_taken_edge (basic_block bb, tree val)
2003 stmt = last_stmt (bb);
2005 #if defined ENABLE_CHECKING
2006 if (stmt == NULL_TREE || !is_ctrl_stmt (stmt))
2010 /* If VAL is a predicate of the form N RELOP N, where N is an
2011 SSA_NAME, we can always determine its truth value (except when
2012 doing floating point comparisons that may involve NaNs). */
2014 && TREE_CODE_CLASS (TREE_CODE (val)) == '<'
2015 && TREE_OPERAND (val, 0) == TREE_OPERAND (val, 1)
2016 && TREE_CODE (TREE_OPERAND (val, 0)) == SSA_NAME
2017 && (TREE_CODE (TREE_TYPE (TREE_OPERAND (val, 0))) != REAL_TYPE
2018 || !HONOR_NANS (TYPE_MODE (TREE_TYPE (TREE_OPERAND (val, 0))))))
2020 enum tree_code code = TREE_CODE (val);
2022 if (code == EQ_EXPR || code == LE_EXPR || code == GE_EXPR)
2023 val = boolean_true_node;
2024 else if (code == LT_EXPR || code == GT_EXPR || code == NE_EXPR)
2025 val = boolean_false_node;
2028 /* If VAL is not a constant, we can't determine which edge might
2030 if (val == NULL || !really_constant_p (val))
2033 if (TREE_CODE (stmt) == COND_EXPR)
2034 return find_taken_edge_cond_expr (bb, val);
2036 if (TREE_CODE (stmt) == SWITCH_EXPR)
2037 return find_taken_edge_switch_expr (bb, val);
2043 /* Given a constant value VAL and the entry block BB to a COND_EXPR
2044 statement, determine which of the two edges will be taken out of the
2045 block. Return NULL if either edge may be taken. */
2048 find_taken_edge_cond_expr (basic_block bb, tree val)
2050 edge true_edge, false_edge;
2052 extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
2054 /* If both edges of the branch lead to the same basic block, it doesn't
2055 matter which edge is taken. */
2056 if (true_edge->dest == false_edge->dest)
2059 /* Otherwise, try to determine which branch of the if() will be taken.
2060 If VAL is a constant but it can't be reduced to a 0 or a 1, then
2061 we don't really know which edge will be taken at runtime. This
2062 may happen when comparing addresses (e.g., if (&var1 == 4)). */
2063 if (integer_nonzerop (val))
2065 else if (integer_zerop (val))
2072 /* Given a constant value VAL and the entry block BB to a SWITCH_EXPR
2073 statement, determine which edge will be taken out of the block. Return
2074 NULL if any edge may be taken. */
2077 find_taken_edge_switch_expr (basic_block bb, tree val)
2079 tree switch_expr, taken_case;
2080 basic_block dest_bb;
2083 if (TREE_CODE (val) != INTEGER_CST)
2086 switch_expr = last_stmt (bb);
2087 taken_case = find_case_label_for_value (switch_expr, val);
2088 dest_bb = label_to_block (CASE_LABEL (taken_case));
2090 e = find_edge (bb, dest_bb);
2097 /* Return the CASE_LABEL_EXPR that SWITCH_EXPR will take for VAL.
2098 We can make optimal use here of the fact that the case labels are
2099 sorted: We can do a binary search for a case matching VAL. */
2102 find_case_label_for_value (tree switch_expr, tree val)
2104 tree vec = SWITCH_LABELS (switch_expr);
2105 size_t low, high, n = TREE_VEC_LENGTH (vec);
2106 tree default_case = TREE_VEC_ELT (vec, n - 1);
2108 for (low = -1, high = n - 1; high - low > 1; )
2110 size_t i = (high + low) / 2;
2111 tree t = TREE_VEC_ELT (vec, i);
2114 /* Cache the result of comparing CASE_LOW and val. */
2115 cmp = tree_int_cst_compare (CASE_LOW (t), val);
2122 if (CASE_HIGH (t) == NULL)
2124 /* A singe-valued case label. */
2130 /* A case range. We can only handle integer ranges. */
2131 if (cmp <= 0 && tree_int_cst_compare (CASE_HIGH (t), val) >= 0)
2136 return default_case;
2140 /* If all the PHI nodes in DEST have alternatives for E1 and E2 and
2141 those alternatives are equal in each of the PHI nodes, then return
2142 true, else return false. */
2145 phi_alternatives_equal (basic_block dest, edge e1, edge e2)
2147 tree phi, val1, val2;
2150 for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi))
2152 n1 = phi_arg_from_edge (phi, e1);
2153 n2 = phi_arg_from_edge (phi, e2);
2155 #ifdef ENABLE_CHECKING
2156 if (n1 < 0 || n2 < 0)
2160 val1 = PHI_ARG_DEF (phi, n1);
2161 val2 = PHI_ARG_DEF (phi, n2);
2163 if (!operand_equal_p (val1, val2, 0))
2171 /* Computing the Dominance Frontier:
2173 As described in Morgan, section 3.5, this may be done simply by
2174 walking the dominator tree bottom-up, computing the frontier for
2175 the children before the parent. When considering a block B,
2176 there are two cases:
2178 (1) A flow graph edge leaving B that does not lead to a child
2179 of B in the dominator tree must be a block that is either equal
2180 to B or not dominated by B. Such blocks belong in the frontier
2183 (2) Consider a block X in the frontier of one of the children C
2184 of B. If X is not equal to B and is not dominated by B, it
2185 is in the frontier of B. */
2188 compute_dominance_frontiers_1 (bitmap *frontiers, basic_block bb, sbitmap done)
2193 SET_BIT (done, bb->index);
2195 /* Do the frontier of the children first. Not all children in the
2196 dominator tree (blocks dominated by this one) are children in the
2197 CFG, so check all blocks. */
2198 for (c = first_dom_son (CDI_DOMINATORS, bb);
2200 c = next_dom_son (CDI_DOMINATORS, c))
2202 if (! TEST_BIT (done, c->index))
2203 compute_dominance_frontiers_1 (frontiers, c, done);
2206 /* Find blocks conforming to rule (1) above. */
2207 for (e = bb->succ; e; e = e->succ_next)
2209 if (e->dest == EXIT_BLOCK_PTR)
2211 if (get_immediate_dominator (CDI_DOMINATORS, e->dest) != bb)
2212 bitmap_set_bit (frontiers[bb->index], e->dest->index);
2215 /* Find blocks conforming to rule (2). */
2216 for (c = first_dom_son (CDI_DOMINATORS, bb);
2218 c = next_dom_son (CDI_DOMINATORS, c))
2222 EXECUTE_IF_SET_IN_BITMAP (frontiers[c->index], 0, x,
2224 if (get_immediate_dominator (CDI_DOMINATORS, BASIC_BLOCK (x)) != bb)
2225 bitmap_set_bit (frontiers[bb->index], x);
2232 compute_dominance_frontiers (bitmap *frontiers)
2234 sbitmap done = sbitmap_alloc (last_basic_block);
2236 timevar_push (TV_DOM_FRONTIERS);
2238 sbitmap_zero (done);
2240 compute_dominance_frontiers_1 (frontiers, ENTRY_BLOCK_PTR->succ->dest, done);
2242 sbitmap_free (done);
2244 timevar_pop (TV_DOM_FRONTIERS);
2249 /*---------------------------------------------------------------------------
2251 ---------------------------------------------------------------------------*/
2253 /* Dump tree-specific information of block BB to file OUTF. */
2256 tree_dump_bb (basic_block bb, FILE *outf, int indent)
2258 dump_generic_bb (outf, bb, indent, TDF_VOPS);
2262 /* Dump a basic block on stderr. */
2265 debug_tree_bb (basic_block bb)
2267 dump_bb (bb, stderr, 0);
2271 /* Dump basic block with index N on stderr. */
2274 debug_tree_bb_n (int n)
2276 debug_tree_bb (BASIC_BLOCK (n));
2277 return BASIC_BLOCK (n);
2281 /* Dump the CFG on stderr.
2283 FLAGS are the same used by the tree dumping functions
2284 (see TDF_* in tree.h). */
2287 debug_tree_cfg (int flags)
2289 dump_tree_cfg (stderr, flags);
2293 /* Dump the program showing basic block boundaries on the given FILE.
2295 FLAGS are the same used by the tree dumping functions (see TDF_* in
2299 dump_tree_cfg (FILE *file, int flags)
2301 if (flags & TDF_DETAILS)
2303 const char *funcname
2304 = lang_hooks.decl_printable_name (current_function_decl, 2);
2307 fprintf (file, ";; Function %s\n\n", funcname);
2308 fprintf (file, ";; \n%d basic blocks, %d edges, last basic block %d.\n\n",
2309 n_basic_blocks, n_edges, last_basic_block);
2311 brief_dump_cfg (file);
2312 fprintf (file, "\n");
2315 if (flags & TDF_STATS)
2316 dump_cfg_stats (file);
2318 dump_function_to_file (current_function_decl, file, flags | TDF_BLOCKS);
2322 /* Dump CFG statistics on FILE. */
2325 dump_cfg_stats (FILE *file)
2327 static long max_num_merged_labels = 0;
2328 unsigned long size, total = 0;
2331 const char * const fmt_str = "%-30s%-13s%12s\n";
2332 const char * const fmt_str_1 = "%-30s%13d%11lu%c\n";
2333 const char * const fmt_str_3 = "%-43s%11lu%c\n";
2334 const char *funcname
2335 = lang_hooks.decl_printable_name (current_function_decl, 2);
2338 fprintf (file, "\nCFG Statistics for %s\n\n", funcname);
2340 fprintf (file, "---------------------------------------------------------\n");
2341 fprintf (file, fmt_str, "", " Number of ", "Memory");
2342 fprintf (file, fmt_str, "", " instances ", "used ");
2343 fprintf (file, "---------------------------------------------------------\n");
2345 size = n_basic_blocks * sizeof (struct basic_block_def);
2347 fprintf (file, fmt_str_1, "Basic blocks", n_basic_blocks,
2348 SCALE (size), LABEL (size));
2354 for (e = bb->succ; e; e = e->succ_next)
2357 size = n_edges * sizeof (struct edge_def);
2359 fprintf (file, fmt_str_1, "Edges", n_edges, SCALE (size), LABEL (size));
2361 size = n_basic_blocks * sizeof (struct bb_ann_d);
2363 fprintf (file, fmt_str_1, "Basic block annotations", n_basic_blocks,
2364 SCALE (size), LABEL (size));
2366 fprintf (file, "---------------------------------------------------------\n");
2367 fprintf (file, fmt_str_3, "Total memory used by CFG data", SCALE (total),
2369 fprintf (file, "---------------------------------------------------------\n");
2370 fprintf (file, "\n");
2372 if (cfg_stats.num_merged_labels > max_num_merged_labels)
2373 max_num_merged_labels = cfg_stats.num_merged_labels;
2375 fprintf (file, "Coalesced label blocks: %ld (Max so far: %ld)\n",
2376 cfg_stats.num_merged_labels, max_num_merged_labels);
2378 fprintf (file, "\n");
2382 /* Dump CFG statistics on stderr. Keep extern so that it's always
2383 linked in the final executable. */
2386 debug_cfg_stats (void)
2388 dump_cfg_stats (stderr);
2392 /* Dump the flowgraph to a .vcg FILE. */
2395 tree_cfg2vcg (FILE *file)
2399 const char *funcname
2400 = lang_hooks.decl_printable_name (current_function_decl, 2);
2402 /* Write the file header. */
2403 fprintf (file, "graph: { title: \"%s\"\n", funcname);
2404 fprintf (file, "node: { title: \"ENTRY\" label: \"ENTRY\" }\n");
2405 fprintf (file, "node: { title: \"EXIT\" label: \"EXIT\" }\n");
2407 /* Write blocks and edges. */
2408 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
2410 fprintf (file, "edge: { sourcename: \"ENTRY\" targetname: \"%d\"",
2413 if (e->flags & EDGE_FAKE)
2414 fprintf (file, " linestyle: dotted priority: 10");
2416 fprintf (file, " linestyle: solid priority: 100");
2418 fprintf (file, " }\n");
2424 enum tree_code head_code, end_code;
2425 const char *head_name, *end_name;
2428 tree first = first_stmt (bb);
2429 tree last = last_stmt (bb);
2433 head_code = TREE_CODE (first);
2434 head_name = tree_code_name[head_code];
2435 head_line = get_lineno (first);
2438 head_name = "no-statement";
2442 end_code = TREE_CODE (last);
2443 end_name = tree_code_name[end_code];
2444 end_line = get_lineno (last);
2447 end_name = "no-statement";
2449 fprintf (file, "node: { title: \"%d\" label: \"#%d\\n%s (%d)\\n%s (%d)\"}\n",
2450 bb->index, bb->index, head_name, head_line, end_name,
2453 for (e = bb->succ; e; e = e->succ_next)
2455 if (e->dest == EXIT_BLOCK_PTR)
2456 fprintf (file, "edge: { sourcename: \"%d\" targetname: \"EXIT\"", bb->index);
2458 fprintf (file, "edge: { sourcename: \"%d\" targetname: \"%d\"", bb->index, e->dest->index);
2460 if (e->flags & EDGE_FAKE)
2461 fprintf (file, " priority: 10 linestyle: dotted");
2463 fprintf (file, " priority: 100 linestyle: solid");
2465 fprintf (file, " }\n");
2468 if (bb->next_bb != EXIT_BLOCK_PTR)
2472 fputs ("}\n\n", file);
2477 /*---------------------------------------------------------------------------
2478 Miscellaneous helpers
2479 ---------------------------------------------------------------------------*/
2481 /* Return true if T represents a stmt that always transfers control. */
2484 is_ctrl_stmt (tree t)
2486 return (TREE_CODE (t) == COND_EXPR
2487 || TREE_CODE (t) == SWITCH_EXPR
2488 || TREE_CODE (t) == GOTO_EXPR
2489 || TREE_CODE (t) == RETURN_EXPR
2490 || TREE_CODE (t) == RESX_EXPR);
2494 /* Return true if T is a statement that may alter the flow of control
2495 (e.g., a call to a non-returning function). */
2498 is_ctrl_altering_stmt (tree t)
2502 #if defined ENABLE_CHECKING
2507 call = get_call_expr_in (t);
2510 /* A non-pure/const CALL_EXPR alters flow control if the current
2511 function has nonlocal labels. */
2512 if (TREE_SIDE_EFFECTS (call) && current_function_has_nonlocal_label)
2515 /* A CALL_EXPR also alters control flow if it does not return. */
2516 if (call_expr_flags (call) & (ECF_NORETURN | ECF_LONGJMP))
2520 /* If a statement can throw, it alters control flow. */
2521 return tree_can_throw_internal (t);
2525 /* Return true if T is a computed goto. */
2528 computed_goto_p (tree t)
2530 return (TREE_CODE (t) == GOTO_EXPR
2531 && TREE_CODE (GOTO_DESTINATION (t)) != LABEL_DECL);
2535 /* Checks whether EXPR is a simple local goto. */
2538 simple_goto_p (tree expr)
2540 return (TREE_CODE (expr) == GOTO_EXPR
2541 && TREE_CODE (GOTO_DESTINATION (expr)) == LABEL_DECL);
2545 /* Return true if T should start a new basic block. PREV_T is the
2546 statement preceding T. It is used when T is a label or a case label.
2547 Labels should only start a new basic block if their previous statement
2548 wasn't a label. Otherwise, sequence of labels would generate
2549 unnecessary basic blocks that only contain a single label. */
2552 stmt_starts_bb_p (tree t, tree prev_t)
2554 enum tree_code code;
2559 /* LABEL_EXPRs start a new basic block only if the preceding
2560 statement wasn't a label of the same type. This prevents the
2561 creation of consecutive blocks that have nothing but a single
2563 code = TREE_CODE (t);
2564 if (code == LABEL_EXPR)
2566 /* Nonlocal and computed GOTO targets always start a new block. */
2567 if (code == LABEL_EXPR
2568 && (DECL_NONLOCAL (LABEL_EXPR_LABEL (t))
2569 || FORCED_LABEL (LABEL_EXPR_LABEL (t))))
2572 if (prev_t && TREE_CODE (prev_t) == code)
2574 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (prev_t)))
2577 cfg_stats.num_merged_labels++;
2588 /* Return true if T should end a basic block. */
2591 stmt_ends_bb_p (tree t)
2593 return is_ctrl_stmt (t) || is_ctrl_altering_stmt (t);
2597 /* Add gotos that used to be represented implicitly in the CFG. */
2600 disband_implicit_edges (void)
2603 block_stmt_iterator last;
2609 last = bsi_last (bb);
2610 stmt = last_stmt (bb);
2612 if (stmt && TREE_CODE (stmt) == COND_EXPR)
2614 /* Remove superfluous gotos from COND_EXPR branches. Moved
2615 from cfg_remove_useless_stmts here since it violates the
2616 invariants for tree--cfg correspondence and thus fits better
2617 here where we do it anyway. */
2618 for (e = bb->succ; e; e = e->succ_next)
2620 if (e->dest != bb->next_bb)
2623 if (e->flags & EDGE_TRUE_VALUE)
2624 COND_EXPR_THEN (stmt) = build_empty_stmt ();
2625 else if (e->flags & EDGE_FALSE_VALUE)
2626 COND_EXPR_ELSE (stmt) = build_empty_stmt ();
2629 e->flags |= EDGE_FALLTHRU;
2635 if (stmt && TREE_CODE (stmt) == RETURN_EXPR)
2637 /* Remove the RETURN_EXPR if we may fall though to the exit
2640 || bb->succ->succ_next
2641 || bb->succ->dest != EXIT_BLOCK_PTR)
2644 if (bb->next_bb == EXIT_BLOCK_PTR
2645 && !TREE_OPERAND (stmt, 0))
2648 bb->succ->flags |= EDGE_FALLTHRU;
2653 /* There can be no fallthru edge if the last statement is a control
2655 if (stmt && is_ctrl_stmt (stmt))
2658 /* Find a fallthru edge and emit the goto if necessary. */
2659 for (e = bb->succ; e; e = e->succ_next)
2660 if (e->flags & EDGE_FALLTHRU)
2663 if (!e || e->dest == bb->next_bb)
2666 if (e->dest == EXIT_BLOCK_PTR)
2669 label = tree_block_label (e->dest);
2671 stmt = build1 (GOTO_EXPR, void_type_node, label);
2672 #ifdef USE_MAPPED_LOCATION
2673 SET_EXPR_LOCATION (stmt, e->goto_locus);
2675 SET_EXPR_LOCUS (stmt, e->goto_locus);
2677 bsi_insert_after (&last, stmt, BSI_NEW_STMT);
2678 e->flags &= ~EDGE_FALLTHRU;
2682 /* Remove block annotations and other datastructures. */
2685 delete_tree_cfg_annotations (void)
2688 if (n_basic_blocks > 0)
2689 free_blocks_annotations ();
2691 label_to_block_map = NULL;
2698 /* Return the first statement in basic block BB. */
2701 first_stmt (basic_block bb)
2703 block_stmt_iterator i = bsi_start (bb);
2704 return !bsi_end_p (i) ? bsi_stmt (i) : NULL_TREE;
2708 /* Return the last statement in basic block BB. */
2711 last_stmt (basic_block bb)
2713 block_stmt_iterator b = bsi_last (bb);
2714 return !bsi_end_p (b) ? bsi_stmt (b) : NULL_TREE;
2718 /* Return a pointer to the last statement in block BB. */
2721 last_stmt_ptr (basic_block bb)
2723 block_stmt_iterator last = bsi_last (bb);
2724 return !bsi_end_p (last) ? bsi_stmt_ptr (last) : NULL;
2728 /* Return the last statement of an otherwise empty block. Return NULL
2729 if the block is totally empty, or if it contains more than one
2733 last_and_only_stmt (basic_block bb)
2735 block_stmt_iterator i = bsi_last (bb);
2741 last = bsi_stmt (i);
2746 /* Empty statements should no longer appear in the instruction stream.
2747 Everything that might have appeared before should be deleted by
2748 remove_useless_stmts, and the optimizers should just bsi_remove
2749 instead of smashing with build_empty_stmt.
2751 Thus the only thing that should appear here in a block containing
2752 one executable statement is a label. */
2753 prev = bsi_stmt (i);
2754 if (TREE_CODE (prev) == LABEL_EXPR)
2761 /* Mark BB as the basic block holding statement T. */
2764 set_bb_for_stmt (tree t, basic_block bb)
2766 if (TREE_CODE (t) == STATEMENT_LIST)
2768 tree_stmt_iterator i;
2769 for (i = tsi_start (t); !tsi_end_p (i); tsi_next (&i))
2770 set_bb_for_stmt (tsi_stmt (i), bb);
2774 stmt_ann_t ann = get_stmt_ann (t);
2777 /* If the statement is a label, add the label to block-to-labels map
2778 so that we can speed up edge creation for GOTO_EXPRs. */
2779 if (TREE_CODE (t) == LABEL_EXPR)
2783 t = LABEL_EXPR_LABEL (t);
2784 uid = LABEL_DECL_UID (t);
2787 LABEL_DECL_UID (t) = uid = cfun->last_label_uid++;
2788 if (VARRAY_SIZE (label_to_block_map) <= (unsigned) uid)
2789 VARRAY_GROW (label_to_block_map, 3 * uid / 2);
2793 #ifdef ENABLE_CHECKING
2794 /* We're moving an existing label. Make sure that we've
2795 removed it from the old block. */
2796 if (bb && VARRAY_BB (label_to_block_map, uid))
2800 VARRAY_BB (label_to_block_map, uid) = bb;
2806 /* Insert statement (or statement list) T before the statement
2807 pointed-to by iterator I. M specifies how to update iterator I
2808 after insertion (see enum bsi_iterator_update). */
2811 bsi_insert_before (block_stmt_iterator *i, tree t, enum bsi_iterator_update m)
2813 set_bb_for_stmt (t, i->bb);
2815 tsi_link_before (&i->tsi, t, m);
2819 /* Insert statement (or statement list) T after the statement
2820 pointed-to by iterator I. M specifies how to update iterator I
2821 after insertion (see enum bsi_iterator_update). */
2824 bsi_insert_after (block_stmt_iterator *i, tree t, enum bsi_iterator_update m)
2826 set_bb_for_stmt (t, i->bb);
2828 tsi_link_after (&i->tsi, t, m);
2832 /* Remove the statement pointed to by iterator I. The iterator is updated
2833 to the next statement. */
2836 bsi_remove (block_stmt_iterator *i)
2838 tree t = bsi_stmt (*i);
2839 set_bb_for_stmt (t, NULL);
2841 tsi_delink (&i->tsi);
2845 /* Move the statement at FROM so it comes right after the statement at TO. */
2848 bsi_move_after (block_stmt_iterator *from, block_stmt_iterator *to)
2850 tree stmt = bsi_stmt (*from);
2852 bsi_insert_after (to, stmt, BSI_SAME_STMT);
2856 /* Move the statement at FROM so it comes right before the statement at TO. */
2859 bsi_move_before (block_stmt_iterator *from, block_stmt_iterator *to)
2861 tree stmt = bsi_stmt (*from);
2863 bsi_insert_before (to, stmt, BSI_SAME_STMT);
2867 /* Move the statement at FROM to the end of basic block BB. */
2870 bsi_move_to_bb_end (block_stmt_iterator *from, basic_block bb)
2872 block_stmt_iterator last = bsi_last (bb);
2874 /* Have to check bsi_end_p because it could be an empty block. */
2875 if (!bsi_end_p (last) && is_ctrl_stmt (bsi_stmt (last)))
2876 bsi_move_before (from, &last);
2878 bsi_move_after (from, &last);
2882 /* Replace the contents of the statement pointed to by iterator BSI
2883 with STMT. If PRESERVE_EH_INFO is true, the exception handling
2884 information of the original statement is preserved. */
2887 bsi_replace (const block_stmt_iterator *bsi, tree stmt, bool preserve_eh_info)
2890 tree orig_stmt = bsi_stmt (*bsi);
2892 SET_EXPR_LOCUS (stmt, EXPR_LOCUS (orig_stmt));
2893 set_bb_for_stmt (stmt, bsi->bb);
2895 /* Preserve EH region information from the original statement, if
2896 requested by the caller. */
2897 if (preserve_eh_info)
2899 eh_region = lookup_stmt_eh_region (orig_stmt);
2901 add_stmt_to_eh_region (stmt, eh_region);
2904 *bsi_stmt_ptr (*bsi) = stmt;
2909 /* Insert the statement pointed-to by BSI into edge E. Every attempt
2910 is made to place the statement in an existing basic block, but
2911 sometimes that isn't possible. When it isn't possible, the edge is
2912 split and the statement is added to the new block.
2914 In all cases, the returned *BSI points to the correct location. The
2915 return value is true if insertion should be done after the location,
2916 or false if it should be done before the location. */
2919 tree_find_edge_insert_loc (edge e, block_stmt_iterator *bsi)
2921 basic_block dest, src;
2927 /* If the destination has one predecessor which has no PHI nodes,
2928 insert there. Except for the exit block.
2930 The requirement for no PHI nodes could be relaxed. Basically we
2931 would have to examine the PHIs to prove that none of them used
2932 the value set by the statement we want to insert on E. That
2933 hardly seems worth the effort. */
2934 if (dest->pred->pred_next == NULL
2935 && ! phi_nodes (dest)
2936 && dest != EXIT_BLOCK_PTR)
2938 *bsi = bsi_start (dest);
2939 if (bsi_end_p (*bsi))
2942 /* Make sure we insert after any leading labels. */
2943 tmp = bsi_stmt (*bsi);
2944 while (TREE_CODE (tmp) == LABEL_EXPR)
2947 if (bsi_end_p (*bsi))
2949 tmp = bsi_stmt (*bsi);
2952 if (bsi_end_p (*bsi))
2954 *bsi = bsi_last (dest);
2961 /* If the source has one successor, the edge is not abnormal and
2962 the last statement does not end a basic block, insert there.
2963 Except for the entry block. */
2965 if ((e->flags & EDGE_ABNORMAL) == 0
2966 && src->succ->succ_next == NULL
2967 && src != ENTRY_BLOCK_PTR)
2969 *bsi = bsi_last (src);
2970 if (bsi_end_p (*bsi))
2973 tmp = bsi_stmt (*bsi);
2974 if (!stmt_ends_bb_p (tmp))
2977 /* Insert code just before returning the value. We may need to decompose
2978 the return in the case it contains non-trivial operand. */
2979 if (TREE_CODE (tmp) == RETURN_EXPR)
2981 tree op = TREE_OPERAND (tmp, 0);
2982 if (!is_gimple_val (op))
2984 if (TREE_CODE (op) != MODIFY_EXPR)
2986 bsi_insert_before (bsi, op, BSI_NEW_STMT);
2987 TREE_OPERAND (tmp, 0) = TREE_OPERAND (op, 0);
2994 /* Otherwise, create a new basic block, and split this edge. */
2995 dest = split_edge (e);
3001 /* This routine will commit all pending edge insertions, creating any new
3002 basic blocks which are necessary.
3004 If specified, NEW_BLOCKS returns a count of the number of new basic
3005 blocks which were created. */
3008 bsi_commit_edge_inserts (int *new_blocks)
3014 blocks = n_basic_blocks;
3016 bsi_commit_edge_inserts_1 (ENTRY_BLOCK_PTR->succ);
3019 for (e = bb->succ; e; e = e->succ_next)
3020 bsi_commit_edge_inserts_1 (e);
3023 *new_blocks = n_basic_blocks - blocks;
3027 /* Commit insertions pending at edge E. */
3030 bsi_commit_edge_inserts_1 (edge e)
3032 if (PENDING_STMT (e))
3034 block_stmt_iterator bsi;
3035 tree stmt = PENDING_STMT (e);
3037 PENDING_STMT (e) = NULL_TREE;
3039 if (tree_find_edge_insert_loc (e, &bsi))
3040 bsi_insert_after (&bsi, stmt, BSI_NEW_STMT);
3042 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
3047 /* Add STMT to the pending list of edge E. No actual insertion is
3048 made until a call to bsi_commit_edge_inserts () is made. */
3051 bsi_insert_on_edge (edge e, tree stmt)
3053 append_to_statement_list (stmt, &PENDING_STMT (e));
3057 /*---------------------------------------------------------------------------
3058 Tree specific functions for CFG manipulation
3059 ---------------------------------------------------------------------------*/
3061 /* Split a (typically critical) edge EDGE_IN. Return the new block.
3062 Abort on abnormal edges. */
3065 tree_split_edge (edge edge_in)
3067 basic_block new_bb, after_bb, dest, src;
3072 /* Abnormal edges cannot be split. */
3073 if (edge_in->flags & EDGE_ABNORMAL)
3077 dest = edge_in->dest;
3079 /* Place the new block in the block list. Try to keep the new block
3080 near its "logical" location. This is of most help to humans looking
3081 at debugging dumps. */
3082 for (e = dest->pred; e; e = e->pred_next)
3083 if (e->src->next_bb == dest)
3086 after_bb = dest->prev_bb;
3088 after_bb = edge_in->src;
3090 new_bb = create_empty_bb (after_bb);
3091 new_edge = make_edge (new_bb, dest, EDGE_FALLTHRU);
3093 /* Find all the PHI arguments on the original edge, and change them to
3094 the new edge. Do it before redirection, so that the argument does not
3096 for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi))
3098 num_elem = PHI_NUM_ARGS (phi);
3099 for (i = 0; i < num_elem; i++)
3100 if (PHI_ARG_EDGE (phi, i) == edge_in)
3102 PHI_ARG_EDGE (phi, i) = new_edge;
3107 if (!redirect_edge_and_branch (edge_in, new_bb))
3110 if (PENDING_STMT (edge_in))
3117 /* Return true when BB has label LABEL in it. */
3120 has_label_p (basic_block bb, tree label)
3122 block_stmt_iterator bsi;
3124 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3126 tree stmt = bsi_stmt (bsi);
3128 if (TREE_CODE (stmt) != LABEL_EXPR)
3130 if (LABEL_EXPR_LABEL (stmt) == label)
3137 /* Callback for walk_tree, check that all elements with address taken are
3138 properly noticed as such. */
3141 verify_expr (tree *tp, int *walk_subtrees, void *data ATTRIBUTE_UNUSED)
3148 /* Check operand N for being valid GIMPLE and give error MSG if not.
3149 We check for constants explicitly since they are not considered
3150 gimple invariants if they overflowed. */
3151 #define CHECK_OP(N, MSG) \
3152 do { if (TREE_CODE_CLASS (TREE_CODE (TREE_OPERAND (t, N))) != 'c' \
3153 && !is_gimple_val (TREE_OPERAND (t, N))) \
3154 { error (MSG); return TREE_OPERAND (t, N); }} while (0)
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 /* Skip any references (they will be checked when we recurse down the
3178 tree) and ensure that any variable used as a prefix is marked
3180 for (x = TREE_OPERAND (t, 0);
3181 (handled_component_p (x)
3182 || TREE_CODE (x) == REALPART_EXPR
3183 || TREE_CODE (x) == IMAGPART_EXPR);
3184 x = TREE_OPERAND (x, 0))
3187 if (TREE_CODE (x) != VAR_DECL && TREE_CODE (x) != PARM_DECL)
3189 if (!TREE_ADDRESSABLE (x))
3191 error ("address taken, but ADDRESSABLE bit not set");
3197 x = TREE_OPERAND (t, 0);
3198 if (TREE_CODE (TREE_TYPE (x)) != BOOLEAN_TYPE)
3200 error ("non-boolean used in condition");
3207 case FIX_TRUNC_EXPR:
3209 case FIX_FLOOR_EXPR:
3210 case FIX_ROUND_EXPR:
3215 case NON_LVALUE_EXPR:
3216 case TRUTH_NOT_EXPR:
3217 CHECK_OP (0, "Invalid operand to unary operator");
3224 case ARRAY_RANGE_REF:
3226 case VIEW_CONVERT_EXPR:
3227 /* We have a nest of references. Verify that each of the operands
3228 that determine where to reference is either a constant or a variable,
3229 verify that the base is valid, and then show we've already checked
3231 while (TREE_CODE (t) == REALPART_EXPR || TREE_CODE (t) == IMAGPART_EXPR
3232 || handled_component_p (t))
3234 if (TREE_CODE (t) == COMPONENT_REF && TREE_OPERAND (t, 2))
3235 CHECK_OP (2, "Invalid COMPONENT_REF offset operator");
3236 else if (TREE_CODE (t) == ARRAY_REF
3237 || TREE_CODE (t) == ARRAY_RANGE_REF)
3239 CHECK_OP (1, "Invalid array index.");
3240 if (TREE_OPERAND (t, 2))
3241 CHECK_OP (2, "Invalid array lower bound.");
3242 if (TREE_OPERAND (t, 3))
3243 CHECK_OP (3, "Invalid array stride.");
3245 else if (TREE_CODE (t) == BIT_FIELD_REF)
3247 CHECK_OP (1, "Invalid operand to BIT_FIELD_REF");
3248 CHECK_OP (2, "Invalid operand to BIT_FIELD_REF");
3251 t = TREE_OPERAND (t, 0);
3254 if (TREE_CODE_CLASS (TREE_CODE (t)) != 'c'
3255 && !is_gimple_lvalue (t))
3257 error ("Invalid reference prefix.");
3269 case UNORDERED_EXPR:
3280 case TRUNC_DIV_EXPR:
3282 case FLOOR_DIV_EXPR:
3283 case ROUND_DIV_EXPR:
3284 case TRUNC_MOD_EXPR:
3286 case FLOOR_MOD_EXPR:
3287 case ROUND_MOD_EXPR:
3289 case EXACT_DIV_EXPR:
3299 CHECK_OP (0, "Invalid operand to binary operator");
3300 CHECK_OP (1, "Invalid operand to binary operator");
3312 /* Verify STMT, return true if STMT is not in GIMPLE form.
3313 TODO: Implement type checking. */
3316 verify_stmt (tree stmt, bool last_in_block)
3320 if (!is_gimple_stmt (stmt))
3322 error ("Is not a valid GIMPLE statement.");
3326 addr = walk_tree (&stmt, verify_expr, NULL, NULL);
3329 debug_generic_stmt (addr);
3333 /* If the statement is marked as part of an EH region, then it is
3334 expected that the statement could throw. Verify that when we
3335 have optimizations that simplify statements such that we prove
3336 that they cannot throw, that we update other data structures
3338 if (lookup_stmt_eh_region (stmt) >= 0)
3340 if (!tree_could_throw_p (stmt))
3342 error ("Statement marked for throw, but doesn't.");
3345 if (!last_in_block && tree_can_throw_internal (stmt))
3347 error ("Statement marked for throw in middle of block.");
3355 debug_generic_stmt (stmt);
3360 /* Return true when the T can be shared. */
3363 tree_node_can_be_shared (tree t)
3365 if (TYPE_P (t) || DECL_P (t)
3366 /* We check for constants explicitly since they are not considered
3367 gimple invariants if they overflowed. */
3368 || TREE_CODE_CLASS (TREE_CODE (t)) == 'c'
3369 || is_gimple_min_invariant (t)
3370 || TREE_CODE (t) == SSA_NAME)
3373 while (((TREE_CODE (t) == ARRAY_REF || TREE_CODE (t) == ARRAY_RANGE_REF)
3374 /* We check for constants explicitly since they are not considered
3375 gimple invariants if they overflowed. */
3376 && (TREE_CODE_CLASS (TREE_CODE (TREE_OPERAND (t, 1))) == 'c'
3377 || is_gimple_min_invariant (TREE_OPERAND (t, 1))))
3378 || (TREE_CODE (t) == COMPONENT_REF
3379 || TREE_CODE (t) == REALPART_EXPR
3380 || TREE_CODE (t) == IMAGPART_EXPR))
3381 t = TREE_OPERAND (t, 0);
3390 /* Called via walk_trees. Verify tree sharing. */
3393 verify_node_sharing (tree * tp, int *walk_subtrees, void *data)
3395 htab_t htab = (htab_t) data;
3398 if (tree_node_can_be_shared (*tp))
3400 *walk_subtrees = false;
3404 slot = htab_find_slot (htab, *tp, INSERT);
3413 /* Verify the GIMPLE statement chain. */
3419 block_stmt_iterator bsi;
3424 timevar_push (TV_TREE_STMT_VERIFY);
3425 htab = htab_create (37, htab_hash_pointer, htab_eq_pointer, NULL);
3432 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
3434 int phi_num_args = PHI_NUM_ARGS (phi);
3436 for (i = 0; i < phi_num_args; i++)
3438 tree t = PHI_ARG_DEF (phi, i);
3441 /* Addressable variables do have SSA_NAMEs but they
3442 are not considered gimple values. */
3443 if (TREE_CODE (t) != SSA_NAME
3444 && TREE_CODE (t) != FUNCTION_DECL
3445 && !is_gimple_val (t))
3447 error ("PHI def is not a GIMPLE value");
3448 debug_generic_stmt (phi);
3449 debug_generic_stmt (t);
3453 addr = walk_tree (&t, verify_expr, NULL, NULL);
3456 debug_generic_stmt (addr);
3460 addr = walk_tree (&t, verify_node_sharing, htab, NULL);
3463 error ("Incorrect sharing of tree nodes");
3464 debug_generic_stmt (phi);
3465 debug_generic_stmt (addr);
3471 for (bsi = bsi_start (bb); !bsi_end_p (bsi); )
3473 tree stmt = bsi_stmt (bsi);
3475 err |= verify_stmt (stmt, bsi_end_p (bsi));
3476 addr = walk_tree (&stmt, verify_node_sharing, htab, NULL);
3479 error ("Incorrect sharing of tree nodes");
3480 debug_generic_stmt (stmt);
3481 debug_generic_stmt (addr);
3488 internal_error ("verify_stmts failed.");
3491 timevar_pop (TV_TREE_STMT_VERIFY);
3495 /* Verifies that the flow information is OK. */
3498 tree_verify_flow_info (void)
3502 block_stmt_iterator bsi;
3506 if (ENTRY_BLOCK_PTR->stmt_list)
3508 error ("ENTRY_BLOCK has a statement list associated with it\n");
3512 if (EXIT_BLOCK_PTR->stmt_list)
3514 error ("EXIT_BLOCK has a statement list associated with it\n");
3518 for (e = EXIT_BLOCK_PTR->pred; e; e = e->pred_next)
3519 if (e->flags & EDGE_FALLTHRU)
3521 error ("Fallthru to exit from bb %d\n", e->src->index);
3527 bool found_ctrl_stmt = false;
3529 /* Skip labels on the start of basic block. */
3530 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3532 if (TREE_CODE (bsi_stmt (bsi)) != LABEL_EXPR)
3535 if (label_to_block (LABEL_EXPR_LABEL (bsi_stmt (bsi))) != bb)
3537 error ("Label %s to block does not match in bb %d\n",
3538 IDENTIFIER_POINTER (DECL_NAME (bsi_stmt (bsi))),
3543 if (decl_function_context (LABEL_EXPR_LABEL (bsi_stmt (bsi)))
3544 != current_function_decl)
3546 error ("Label %s has incorrect context in bb %d\n",
3547 IDENTIFIER_POINTER (DECL_NAME (bsi_stmt (bsi))),
3553 /* Verify that body of basic block BB is free of control flow. */
3554 for (; !bsi_end_p (bsi); bsi_next (&bsi))
3556 tree stmt = bsi_stmt (bsi);
3558 if (found_ctrl_stmt)
3560 error ("Control flow in the middle of basic block %d\n",
3565 if (stmt_ends_bb_p (stmt))
3566 found_ctrl_stmt = true;
3568 if (TREE_CODE (stmt) == LABEL_EXPR)
3570 error ("Label %s in the middle of basic block %d\n",
3571 IDENTIFIER_POINTER (DECL_NAME (stmt)),
3576 bsi = bsi_last (bb);
3577 if (bsi_end_p (bsi))
3580 stmt = bsi_stmt (bsi);
3582 if (is_ctrl_stmt (stmt))
3584 for (e = bb->succ; e; e = e->succ_next)
3585 if (e->flags & EDGE_FALLTHRU)
3587 error ("Fallthru edge after a control statement in bb %d \n",
3593 switch (TREE_CODE (stmt))
3599 if (TREE_CODE (COND_EXPR_THEN (stmt)) != GOTO_EXPR
3600 || TREE_CODE (COND_EXPR_ELSE (stmt)) != GOTO_EXPR)
3602 error ("Structured COND_EXPR at the end of bb %d\n", bb->index);
3606 extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
3608 if (!true_edge || !false_edge
3609 || !(true_edge->flags & EDGE_TRUE_VALUE)
3610 || !(false_edge->flags & EDGE_FALSE_VALUE)
3611 || (true_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL))
3612 || (false_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL))
3613 || bb->succ->succ_next->succ_next)
3615 error ("Wrong outgoing edge flags at end of bb %d\n",
3620 if (!has_label_p (true_edge->dest,
3621 GOTO_DESTINATION (COND_EXPR_THEN (stmt))))
3623 error ("`then' label does not match edge at end of bb %d\n",
3628 if (!has_label_p (false_edge->dest,
3629 GOTO_DESTINATION (COND_EXPR_ELSE (stmt))))
3631 error ("`else' label does not match edge at end of bb %d\n",
3639 if (simple_goto_p (stmt))
3641 error ("Explicit goto at end of bb %d\n", bb->index);
3646 /* FIXME. We should double check that the labels in the
3647 destination blocks have their address taken. */
3648 for (e = bb->succ; e; e = e->succ_next)
3649 if ((e->flags & (EDGE_FALLTHRU | EDGE_TRUE_VALUE
3650 | EDGE_FALSE_VALUE))
3651 || !(e->flags & EDGE_ABNORMAL))
3653 error ("Wrong outgoing edge flags at end of bb %d\n",
3661 if (!bb->succ || bb->succ->succ_next
3662 || (bb->succ->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL
3663 | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
3665 error ("Wrong outgoing edge flags at end of bb %d\n", bb->index);
3668 if (bb->succ->dest != EXIT_BLOCK_PTR)
3670 error ("Return edge does not point to exit in bb %d\n",
3683 vec = SWITCH_LABELS (stmt);
3684 n = TREE_VEC_LENGTH (vec);
3686 /* Mark all the destination basic blocks. */
3687 for (i = 0; i < n; ++i)
3689 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
3690 basic_block label_bb = label_to_block (lab);
3692 if (label_bb->aux && label_bb->aux != (void *)1)
3694 label_bb->aux = (void *)1;
3697 /* Verify that the case labels are sorted. */
3698 prev = TREE_VEC_ELT (vec, 0);
3699 for (i = 1; i < n - 1; ++i)
3701 tree c = TREE_VEC_ELT (vec, i);
3704 error ("Found default case not at end of case vector");
3708 if (! tree_int_cst_lt (CASE_LOW (prev), CASE_LOW (c)))
3710 error ("Case labels not sorted:\n ");
3711 print_generic_expr (stderr, prev, 0);
3712 fprintf (stderr," is greater than ");
3713 print_generic_expr (stderr, c, 0);
3714 fprintf (stderr," but comes before it.\n");
3719 if (CASE_LOW (TREE_VEC_ELT (vec, n - 1)))
3721 error ("No default case found at end of case vector");
3725 for (e = bb->succ; e; e = e->succ_next)
3729 error ("Extra outgoing edge %d->%d\n",
3730 bb->index, e->dest->index);
3733 e->dest->aux = (void *)2;
3734 if ((e->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL
3735 | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
3737 error ("Wrong outgoing edge flags at end of bb %d\n",
3743 /* Check that we have all of them. */
3744 for (i = 0; i < n; ++i)
3746 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
3747 basic_block label_bb = label_to_block (lab);
3749 if (label_bb->aux != (void *)2)
3751 error ("Missing edge %i->%i\n",
3752 bb->index, label_bb->index);
3757 for (e = bb->succ; e; e = e->succ_next)
3758 e->dest->aux = (void *)0;
3765 if (dom_computed[CDI_DOMINATORS] >= DOM_NO_FAST_QUERY)
3766 verify_dominators (CDI_DOMINATORS);
3772 /* Updates phi nodes after creating forwarder block joined
3773 by edge FALLTHRU. */
3776 tree_make_forwarder_block (edge fallthru)
3779 basic_block dummy, bb;
3780 tree phi, new_phi, var, prev, next;
3782 dummy = fallthru->src;
3783 bb = fallthru->dest;
3785 if (!bb->pred->pred_next)
3788 /* If we redirected a branch we must create new phi nodes at the
3790 for (phi = phi_nodes (dummy); phi; phi = PHI_CHAIN (phi))
3792 var = PHI_RESULT (phi);
3793 new_phi = create_phi_node (var, bb);
3794 SSA_NAME_DEF_STMT (var) = new_phi;
3795 SET_PHI_RESULT (phi, make_ssa_name (SSA_NAME_VAR (var), phi));
3796 add_phi_arg (&new_phi, PHI_RESULT (phi), fallthru);
3799 /* Ensure that the PHI node chain is in the same order. */
3801 for (phi = phi_nodes (bb); phi; phi = next)
3803 next = PHI_CHAIN (phi);
3804 PHI_CHAIN (phi) = prev;
3807 set_phi_nodes (bb, prev);
3809 /* Add the arguments we have stored on edges. */
3810 for (e = bb->pred; e; e = e->pred_next)
3815 for (phi = phi_nodes (bb), var = PENDING_STMT (e);
3817 phi = PHI_CHAIN (phi), var = TREE_CHAIN (var))
3818 add_phi_arg (&phi, TREE_VALUE (var), e);
3820 PENDING_STMT (e) = NULL;
3825 /* Return true if basic block BB does nothing except pass control
3826 flow to another block and that we can safely insert a label at
3827 the start of the successor block. */
3830 tree_forwarder_block_p (basic_block bb)
3832 block_stmt_iterator bsi;
3835 /* If we have already determined that this block is not forwardable,
3836 then no further checks are necessary. */
3837 if (! bb_ann (bb)->forwardable)
3840 /* BB must have a single outgoing normal edge. Otherwise it can not be
3841 a forwarder block. */
3843 || bb->succ->succ_next
3844 || bb->succ->dest == EXIT_BLOCK_PTR
3845 || (bb->succ->flags & EDGE_ABNORMAL)
3846 || bb == ENTRY_BLOCK_PTR)
3848 bb_ann (bb)->forwardable = 0;
3852 /* Successors of the entry block are not forwarders. */
3853 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
3856 bb_ann (bb)->forwardable = 0;
3860 /* BB can not have any PHI nodes. This could potentially be relaxed
3861 early in compilation if we re-rewrote the variables appearing in
3862 any PHI nodes in forwarder blocks. */
3865 bb_ann (bb)->forwardable = 0;
3869 /* Now walk through the statements. We can ignore labels, anything else
3870 means this is not a forwarder block. */
3871 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3873 tree stmt = bsi_stmt (bsi);
3875 switch (TREE_CODE (stmt))
3878 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)))
3883 bb_ann (bb)->forwardable = 0;
3892 /* Thread jumps over empty statements.
3894 This code should _not_ thread over obviously equivalent conditions
3895 as that requires nontrivial updates to the SSA graph. */
3900 edge e, next, last, old;
3901 basic_block bb, dest, tmp, old_dest, dom;
3904 bool retval = false;
3907 bb_ann (bb)->forwardable = 1;
3909 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb)
3911 /* Don't waste time on unreachable blocks. */
3915 /* Nor on forwarders. */
3916 if (tree_forwarder_block_p (bb))
3919 /* This block is now part of a forwarding path, mark it as not
3920 forwardable so that we can detect loops. This bit will be
3922 bb_ann (bb)->forwardable = 0;
3924 /* Examine each of our block's successors to see if it is
3926 for (e = bb->succ; e; e = next)
3928 next = e->succ_next;
3930 /* If the edge is abnormal or its destination is not
3931 forwardable, then there's nothing to do. */
3932 if ((e->flags & EDGE_ABNORMAL)
3933 || !tree_forwarder_block_p (e->dest))
3936 /* Now walk through as many forwarder block as possible to
3937 find the ultimate destination we want to thread our jump
3939 last = e->dest->succ;
3940 bb_ann (e->dest)->forwardable = 0;
3941 for (dest = e->dest->succ->dest;
3942 tree_forwarder_block_p (dest);
3944 dest = dest->succ->dest)
3946 /* An infinite loop detected. We redirect the edge anyway, so
3947 that the loop is shrunk into single basic block. */
3948 if (!bb_ann (dest)->forwardable)
3951 if (dest->succ->dest == EXIT_BLOCK_PTR)
3954 bb_ann (dest)->forwardable = 0;
3957 /* Reset the forwardable marks to 1. */
3960 tmp = tmp->succ->dest)
3961 bb_ann (tmp)->forwardable = 1;
3963 if (dest == e->dest)
3966 old = find_edge (bb, dest);
3969 /* If there already is an edge, check whether the values
3970 in phi nodes differ. */
3971 if (!phi_alternatives_equal (dest, last, old))
3973 /* The previous block is forwarder. Redirect our jump
3974 to that target instead since we know it has no PHI
3975 nodes that will need updating. */
3978 /* That might mean that no forwarding at all is possible. */
3979 if (dest == e->dest)
3982 old = find_edge (bb, dest);
3986 /* Perform the redirection. */
3989 e = redirect_edge_and_branch (e, dest);
3993 /* Update PHI nodes. We know that the new argument should
3994 have the same value as the argument associated with LAST.
3995 Otherwise we would have changed our target block above. */
3996 for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi))
3998 arg = phi_arg_from_edge (phi, last);
4001 add_phi_arg (&phi, PHI_ARG_DEF (phi, arg), e);
4005 /* Update the dominators. */
4006 if (dom_computed[CDI_DOMINATORS] >= DOM_CONS_OK)
4008 /* Remove the unreachable blocks (observe that if all blocks
4009 were reachable before, only those in the path we threaded
4010 over and did not have any predecessor outside of the path
4011 become unreachable). */
4012 for (; old_dest != dest; old_dest = tmp)
4014 tmp = old_dest->succ->dest;
4019 delete_basic_block (old_dest);
4021 /* If the dominator of the destination was in the path, set its
4022 dominator to the start of the redirected edge. */
4023 if (get_immediate_dominator (CDI_DOMINATORS, old_dest) == NULL)
4024 set_immediate_dominator (CDI_DOMINATORS, old_dest, bb);
4026 /* Now proceed like if we forwarded just over one edge at a time.
4027 Algorithm for forwarding over edge A --> B then is
4030 idom (B) = idom (A);
4031 recount_idom (A); */
4033 for (; old_dest != dest; old_dest = tmp)
4035 tmp = old_dest->succ->dest;
4037 if (get_immediate_dominator (CDI_DOMINATORS, tmp) == old_dest)
4039 dom = get_immediate_dominator (CDI_DOMINATORS, old_dest);
4040 set_immediate_dominator (CDI_DOMINATORS, tmp, dom);
4043 dom = recount_dominator (CDI_DOMINATORS, old_dest);
4044 set_immediate_dominator (CDI_DOMINATORS, old_dest, dom);
4049 /* Reset the forwardable bit on our block since it's no longer in
4050 a forwarding chain path. */
4051 bb_ann (bb)->forwardable = 1;
4058 /* Return a non-special label in the head of basic block BLOCK.
4059 Create one if it doesn't exist. */
4062 tree_block_label (basic_block bb)
4064 block_stmt_iterator i, s = bsi_start (bb);
4068 for (i = s; !bsi_end_p (i); first = false, bsi_next (&i))
4070 stmt = bsi_stmt (i);
4071 if (TREE_CODE (stmt) != LABEL_EXPR)
4073 label = LABEL_EXPR_LABEL (stmt);
4074 if (!DECL_NONLOCAL (label))
4077 bsi_move_before (&i, &s);
4082 label = create_artificial_label ();
4083 stmt = build1 (LABEL_EXPR, void_type_node, label);
4084 bsi_insert_before (&s, stmt, BSI_NEW_STMT);
4089 /* Attempt to perform edge redirection by replacing a possibly complex
4090 jump instruction by a goto or by removing the jump completely.
4091 This can apply only if all edges now point to the same block. The
4092 parameters and return values are equivalent to
4093 redirect_edge_and_branch. */
4096 tree_try_redirect_by_replacing_jump (edge e, basic_block target)
4098 basic_block src = e->src;
4100 block_stmt_iterator b;
4103 /* Verify that all targets will be TARGET. */
4104 for (tmp = src->succ; tmp; tmp = tmp->succ_next)
4105 if (tmp->dest != target && tmp != e)
4114 stmt = bsi_stmt (b);
4116 if (TREE_CODE (stmt) == COND_EXPR
4117 || TREE_CODE (stmt) == SWITCH_EXPR)
4120 e = ssa_redirect_edge (e, target);
4121 e->flags = EDGE_FALLTHRU;
4129 /* Redirect E to DEST. Return NULL on failure. Otherwise, return the
4130 edge representing the redirected branch. */
4133 tree_redirect_edge_and_branch (edge e, basic_block dest)
4135 basic_block bb = e->src;
4136 block_stmt_iterator bsi;
4140 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
4143 if (e->src != ENTRY_BLOCK_PTR
4144 && (ret = tree_try_redirect_by_replacing_jump (e, dest)))
4147 if (e->dest == dest)
4150 label = tree_block_label (dest);
4152 bsi = bsi_last (bb);
4153 stmt = bsi_end_p (bsi) ? NULL : bsi_stmt (bsi);
4155 switch (stmt ? TREE_CODE (stmt) : ERROR_MARK)
4158 stmt = (e->flags & EDGE_TRUE_VALUE
4159 ? COND_EXPR_THEN (stmt)
4160 : COND_EXPR_ELSE (stmt));
4161 GOTO_DESTINATION (stmt) = label;
4165 /* No non-abnormal edges should lead from a non-simple goto, and
4166 simple ones should be represented implicitly. */
4171 tree vec = SWITCH_LABELS (stmt);
4172 size_t i, n = TREE_VEC_LENGTH (vec);
4174 for (i = 0; i < n; ++i)
4176 tree elt = TREE_VEC_ELT (vec, i);
4177 if (label_to_block (CASE_LABEL (elt)) == e->dest)
4178 CASE_LABEL (elt) = label;
4185 e->flags |= EDGE_FALLTHRU;
4189 /* Otherwise it must be a fallthru edge, and we don't need to
4190 do anything besides redirecting it. */
4191 if (!(e->flags & EDGE_FALLTHRU))
4196 /* Update/insert PHI nodes as necessary. */
4198 /* Now update the edges in the CFG. */
4199 e = ssa_redirect_edge (e, dest);
4205 /* Simple wrapper, as we can always redirect fallthru edges. */
4208 tree_redirect_edge_and_branch_force (edge e, basic_block dest)
4210 e = tree_redirect_edge_and_branch (e, dest);
4218 /* Splits basic block BB after statement STMT (but at least after the
4219 labels). If STMT is NULL, BB is split just after the labels. */
4222 tree_split_block (basic_block bb, void *stmt)
4224 block_stmt_iterator bsi, bsi_tgt;
4229 new_bb = create_empty_bb (bb);
4231 /* Redirect the outgoing edges. */
4232 new_bb->succ = bb->succ;
4234 for (e = new_bb->succ; e; e = e->succ_next)
4237 if (stmt && TREE_CODE ((tree) stmt) == LABEL_EXPR)
4240 /* Move everything from BSI to the new basic block. */
4241 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4243 act = bsi_stmt (bsi);
4244 if (TREE_CODE (act) == LABEL_EXPR)
4257 bsi_tgt = bsi_start (new_bb);
4258 while (!bsi_end_p (bsi))
4260 act = bsi_stmt (bsi);
4262 bsi_insert_after (&bsi_tgt, act, BSI_NEW_STMT);
4269 /* Moves basic block BB after block AFTER. */
4272 tree_move_block_after (basic_block bb, basic_block after)
4274 if (bb->prev_bb == after)
4278 link_block (bb, after);
4284 /* Return true if basic_block can be duplicated. */
4287 tree_can_duplicate_bb_p (basic_block bb ATTRIBUTE_UNUSED)
4293 /* Create a duplicate of the basic block BB. NOTE: This does not
4294 preserve SSA form. */
4297 tree_duplicate_bb (basic_block bb)
4300 block_stmt_iterator bsi, bsi_tgt;
4303 v_may_def_optype v_may_defs;
4304 v_must_def_optype v_must_defs;
4307 new_bb = create_empty_bb (EXIT_BLOCK_PTR->prev_bb);
4309 for (phi = phi_nodes (bb); phi; phi = TREE_CHAIN (phi))
4311 mark_for_rewrite (PHI_RESULT (phi));
4314 bsi_tgt = bsi_start (new_bb);
4315 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4317 tree stmt = bsi_stmt (bsi);
4320 if (TREE_CODE (stmt) == LABEL_EXPR)
4323 /* Record the definitions. */
4324 get_stmt_operands (stmt);
4326 defs = STMT_DEF_OPS (stmt);
4327 for (j = 0; j < NUM_DEFS (defs); j++)
4328 mark_for_rewrite (DEF_OP (defs, j));
4330 v_may_defs = STMT_V_MAY_DEF_OPS (stmt);
4331 for (j = 0; j < NUM_V_MAY_DEFS (v_may_defs); j++)
4332 mark_for_rewrite (V_MAY_DEF_RESULT (v_may_defs, j));
4334 v_must_defs = STMT_V_MUST_DEF_OPS (stmt);
4335 for (j = 0; j < NUM_V_MUST_DEFS (v_must_defs); j++)
4336 mark_for_rewrite (V_MUST_DEF_OP (v_must_defs, j));
4338 copy = unshare_expr (stmt);
4340 /* Copy also the virtual operands. */
4341 get_stmt_ann (copy);
4342 copy_virtual_operands (copy, stmt);
4344 bsi_insert_after (&bsi_tgt, copy, BSI_NEW_STMT);
4351 /* Dump FUNCTION_DECL FN to file FILE using FLAGS (see TDF_* in tree.h) */
4354 dump_function_to_file (tree fn, FILE *file, int flags)
4356 tree arg, vars, var;
4357 bool ignore_topmost_bind = false, any_var = false;
4361 fprintf (file, "%s (", lang_hooks.decl_printable_name (fn, 2));
4363 arg = DECL_ARGUMENTS (fn);
4366 print_generic_expr (file, arg, dump_flags);
4367 if (TREE_CHAIN (arg))
4368 fprintf (file, ", ");
4369 arg = TREE_CHAIN (arg);
4371 fprintf (file, ")\n");
4373 if (flags & TDF_RAW)
4375 dump_node (fn, TDF_SLIM | flags, file);
4379 /* When GIMPLE is lowered, the variables are no longer available in
4380 BIND_EXPRs, so display them separately. */
4381 if (cfun && cfun->unexpanded_var_list)
4383 ignore_topmost_bind = true;
4385 fprintf (file, "{\n");
4386 for (vars = cfun->unexpanded_var_list; vars; vars = TREE_CHAIN (vars))
4388 var = TREE_VALUE (vars);
4390 print_generic_decl (file, var, flags);
4391 fprintf (file, "\n");
4397 if (basic_block_info)
4399 /* Make a CFG based dump. */
4400 check_bb_profile (ENTRY_BLOCK_PTR, file);
4401 if (!ignore_topmost_bind)
4402 fprintf (file, "{\n");
4404 if (any_var && n_basic_blocks)
4405 fprintf (file, "\n");
4408 dump_generic_bb (file, bb, 2, flags);
4410 fprintf (file, "}\n");
4411 check_bb_profile (EXIT_BLOCK_PTR, file);
4417 /* Make a tree based dump. */
4418 chain = DECL_SAVED_TREE (fn);
4420 if (TREE_CODE (chain) == BIND_EXPR)
4422 if (ignore_topmost_bind)
4424 chain = BIND_EXPR_BODY (chain);
4432 if (!ignore_topmost_bind)
4433 fprintf (file, "{\n");
4438 fprintf (file, "\n");
4440 print_generic_stmt_indented (file, chain, flags, indent);
4441 if (ignore_topmost_bind)
4442 fprintf (file, "}\n");
4445 fprintf (file, "\n\n");
4449 /* Pretty print of the loops intermediate representation. */
4450 static void print_loop (FILE *, struct loop *, int);
4451 static void print_pred_bbs (FILE *, edge);
4452 static void print_succ_bbs (FILE *, edge);
4455 /* Print the predecessors indexes of edge E on FILE. */
4458 print_pred_bbs (FILE *file, edge e)
4463 else if (e->pred_next == NULL)
4464 fprintf (file, "bb_%d", e->src->index);
4468 fprintf (file, "bb_%d, ", e->src->index);
4469 print_pred_bbs (file, e->pred_next);
4474 /* Print the successors indexes of edge E on FILE. */
4477 print_succ_bbs (FILE *file, edge e)
4481 else if (e->succ_next == NULL)
4482 fprintf (file, "bb_%d", e->dest->index);
4485 fprintf (file, "bb_%d, ", e->dest->index);
4486 print_succ_bbs (file, e->succ_next);
4491 /* Pretty print LOOP on FILE, indented INDENT spaces. */
4494 print_loop (FILE *file, struct loop *loop, int indent)
4502 s_indent = (char *) alloca ((size_t) indent + 1);
4503 memset ((void *) s_indent, ' ', (size_t) indent);
4504 s_indent[indent] = '\0';
4506 /* Print the loop's header. */
4507 fprintf (file, "%sloop_%d\n", s_indent, loop->num);
4509 /* Print the loop's body. */
4510 fprintf (file, "%s{\n", s_indent);
4512 if (bb->loop_father == loop)
4514 /* Print the basic_block's header. */
4515 fprintf (file, "%s bb_%d (preds = {", s_indent, bb->index);
4516 print_pred_bbs (file, bb->pred);
4517 fprintf (file, "}, succs = {");
4518 print_succ_bbs (file, bb->succ);
4519 fprintf (file, "})\n");
4521 /* Print the basic_block's body. */
4522 fprintf (file, "%s {\n", s_indent);
4523 tree_dump_bb (bb, file, indent + 4);
4524 fprintf (file, "%s }\n", s_indent);
4527 print_loop (file, loop->inner, indent + 2);
4528 fprintf (file, "%s}\n", s_indent);
4529 print_loop (file, loop->next, indent);
4533 /* Follow a CFG edge from the entry point of the program, and on entry
4534 of a loop, pretty print the loop structure on FILE. */
4537 print_loop_ir (FILE *file)
4541 bb = BASIC_BLOCK (0);
4542 if (bb && bb->loop_father)
4543 print_loop (file, bb->loop_father, 0);
4547 /* Debugging loops structure at tree level. */
4550 debug_loop_ir (void)
4552 print_loop_ir (stderr);
4556 /* Return true if BB ends with a call, possibly followed by some
4557 instructions that must stay with the call. Return false,
4561 tree_block_ends_with_call_p (basic_block bb)
4563 block_stmt_iterator bsi = bsi_last (bb);
4564 return get_call_expr_in (bsi_stmt (bsi)) != NULL;
4568 /* Return true if BB ends with a conditional branch. Return false,
4572 tree_block_ends_with_condjump_p (basic_block bb)
4574 tree stmt = tsi_stmt (bsi_last (bb).tsi);
4575 return (TREE_CODE (stmt) == COND_EXPR);
4579 /* Return true if we need to add fake edge to exit at statement T.
4580 Helper function for tree_flow_call_edges_add. */
4583 need_fake_edge_p (tree t)
4587 /* NORETURN and LONGJMP calls already have an edge to exit.
4588 CONST, PURE and ALWAYS_RETURN calls do not need one.
4589 We don't currently check for CONST and PURE here, although
4590 it would be a good idea, because those attributes are
4591 figured out from the RTL in mark_constant_function, and
4592 the counter incrementation code from -fprofile-arcs
4593 leads to different results from -fbranch-probabilities. */
4594 call = get_call_expr_in (t);
4596 && !(call_expr_flags (call) &
4597 (ECF_NORETURN | ECF_LONGJMP | ECF_ALWAYS_RETURN)))
4600 if (TREE_CODE (t) == ASM_EXPR
4601 && (ASM_VOLATILE_P (t) || ASM_INPUT_P (t)))
4608 /* Add fake edges to the function exit for any non constant and non
4609 noreturn calls, volatile inline assembly in the bitmap of blocks
4610 specified by BLOCKS or to the whole CFG if BLOCKS is zero. Return
4611 the number of blocks that were split.
4613 The goal is to expose cases in which entering a basic block does
4614 not imply that all subsequent instructions must be executed. */
4617 tree_flow_call_edges_add (sbitmap blocks)
4620 int blocks_split = 0;
4621 int last_bb = last_basic_block;
4622 bool check_last_block = false;
4624 if (n_basic_blocks == 0)
4628 check_last_block = true;
4630 check_last_block = TEST_BIT (blocks, EXIT_BLOCK_PTR->prev_bb->index);
4632 /* In the last basic block, before epilogue generation, there will be
4633 a fallthru edge to EXIT. Special care is required if the last insn
4634 of the last basic block is a call because make_edge folds duplicate
4635 edges, which would result in the fallthru edge also being marked
4636 fake, which would result in the fallthru edge being removed by
4637 remove_fake_edges, which would result in an invalid CFG.
4639 Moreover, we can't elide the outgoing fake edge, since the block
4640 profiler needs to take this into account in order to solve the minimal
4641 spanning tree in the case that the call doesn't return.
4643 Handle this by adding a dummy instruction in a new last basic block. */
4644 if (check_last_block)
4646 basic_block bb = EXIT_BLOCK_PTR->prev_bb;
4647 block_stmt_iterator bsi = bsi_last (bb);
4649 if (!bsi_end_p (bsi))
4652 if (need_fake_edge_p (t))
4656 for (e = bb->succ; e; e = e->succ_next)
4657 if (e->dest == EXIT_BLOCK_PTR)
4659 bsi_insert_on_edge (e, build_empty_stmt ());
4660 bsi_commit_edge_inserts ((int *)NULL);
4666 /* Now add fake edges to the function exit for any non constant
4667 calls since there is no way that we can determine if they will
4669 for (i = 0; i < last_bb; i++)
4671 basic_block bb = BASIC_BLOCK (i);
4672 block_stmt_iterator bsi;
4673 tree stmt, last_stmt;
4678 if (blocks && !TEST_BIT (blocks, i))
4681 bsi = bsi_last (bb);
4682 if (!bsi_end_p (bsi))
4684 last_stmt = bsi_stmt (bsi);
4687 stmt = bsi_stmt (bsi);
4688 if (need_fake_edge_p (stmt))
4691 /* The handling above of the final block before the
4692 epilogue should be enough to verify that there is
4693 no edge to the exit block in CFG already.
4694 Calling make_edge in such case would cause us to
4695 mark that edge as fake and remove it later. */
4696 #ifdef ENABLE_CHECKING
4697 if (stmt == last_stmt)
4698 for (e = bb->succ; e; e = e->succ_next)
4699 if (e->dest == EXIT_BLOCK_PTR)
4703 /* Note that the following may create a new basic block
4704 and renumber the existing basic blocks. */
4705 if (stmt != last_stmt)
4707 e = split_block (bb, stmt);
4711 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
4715 while (!bsi_end_p (bsi));
4720 verify_flow_info ();
4722 return blocks_split;
4726 tree_purge_dead_eh_edges (basic_block bb)
4728 bool changed = false;
4730 tree stmt = last_stmt (bb);
4732 if (stmt && tree_can_throw_internal (stmt))
4735 for (e = bb->succ; e ; e = next)
4737 next = e->succ_next;
4738 if (e->flags & EDGE_EH)
4740 ssa_remove_edge (e);
4749 tree_purge_all_dead_eh_edges (bitmap blocks)
4751 bool changed = false;
4754 EXECUTE_IF_SET_IN_BITMAP (blocks, 0, i,
4755 { changed |= tree_purge_dead_eh_edges (BASIC_BLOCK (i)); });
4760 struct cfg_hooks tree_cfg_hooks = {
4762 tree_verify_flow_info,
4763 tree_dump_bb, /* dump_bb */
4764 create_bb, /* create_basic_block */
4765 tree_redirect_edge_and_branch,/* redirect_edge_and_branch */
4766 tree_redirect_edge_and_branch_force,/* redirect_edge_and_branch_force */
4767 remove_bb, /* delete_basic_block */
4768 tree_split_block, /* split_block */
4769 tree_move_block_after, /* move_block_after */
4770 tree_can_merge_blocks_p, /* can_merge_blocks_p */
4771 tree_merge_blocks, /* merge_blocks */
4772 tree_predict_edge, /* predict_edge */
4773 tree_predicted_by_p, /* predicted_by_p */
4774 tree_can_duplicate_bb_p, /* can_duplicate_block_p */
4775 tree_duplicate_bb, /* duplicate_block */
4776 tree_split_edge, /* split_edge */
4777 tree_make_forwarder_block, /* make_forward_block */
4778 NULL, /* tidy_fallthru_edge */
4779 tree_block_ends_with_call_p, /* block_ends_with_call_p */
4780 tree_block_ends_with_condjump_p, /* block_ends_with_condjump_p */
4781 tree_flow_call_edges_add /* flow_call_edges_add */
4785 /* Split all critical edges. */
4788 split_critical_edges (void)
4795 for (e = bb->succ; e ; e = e->succ_next)
4796 if (EDGE_CRITICAL_P (e) && !(e->flags & EDGE_ABNORMAL))
4803 struct tree_opt_pass pass_split_crit_edges =
4805 "crited", /* name */
4807 split_critical_edges, /* execute */
4810 0, /* static_pass_number */
4811 TV_TREE_SPLIT_EDGES, /* tv_id */
4812 PROP_cfg, /* properties required */
4813 PROP_no_crit_edges, /* properties_provided */
4814 0, /* properties_destroyed */
4815 0, /* todo_flags_start */
4816 TODO_dump_func, /* todo_flags_finish */
4820 /* Return EXP if it is a valid GIMPLE rvalue, else gimplify it into
4821 a temporary, make sure and register it to be renamed if necessary,
4822 and finally return the temporary. Put the statements to compute
4823 EXP before the current statement in BSI. */
4826 gimplify_val (block_stmt_iterator *bsi, tree type, tree exp)
4828 tree t, new_stmt, orig_stmt;
4830 if (is_gimple_val (exp))
4833 t = make_rename_temp (type, NULL);
4834 new_stmt = build (MODIFY_EXPR, type, t, exp);
4836 orig_stmt = bsi_stmt (*bsi);
4837 SET_EXPR_LOCUS (new_stmt, EXPR_LOCUS (orig_stmt));
4838 TREE_BLOCK (new_stmt) = TREE_BLOCK (orig_stmt);
4840 bsi_insert_before (bsi, new_stmt, BSI_SAME_STMT);
4845 /* Build a ternary operation and gimplify it. Emit code before BSI.
4846 Return the gimple_val holding the result. */
4849 gimplify_build3 (block_stmt_iterator *bsi, enum tree_code code,
4850 tree type, tree a, tree b, tree c)
4854 ret = fold (build3 (code, type, a, b, c));
4857 return gimplify_val (bsi, type, ret);
4860 /* Build a binary operation and gimplify it. Emit code before BSI.
4861 Return the gimple_val holding the result. */
4864 gimplify_build2 (block_stmt_iterator *bsi, enum tree_code code,
4865 tree type, tree a, tree b)
4869 ret = fold (build2 (code, type, a, b));
4872 return gimplify_val (bsi, type, ret);
4875 /* Build a unary operation and gimplify it. Emit code before BSI.
4876 Return the gimple_val holding the result. */
4879 gimplify_build1 (block_stmt_iterator *bsi, enum tree_code code, tree type,
4884 ret = fold (build1 (code, type, a));
4887 return gimplify_val (bsi, type, ret);
4892 /* Emit return warnings. */
4895 execute_warn_function_return (void)
4897 #ifdef USE_MAPPED_LOCATION
4898 source_location location;
4905 if (warn_missing_noreturn
4906 && !TREE_THIS_VOLATILE (cfun->decl)
4907 && EXIT_BLOCK_PTR->pred == NULL
4908 && !lang_hooks.function.missing_noreturn_ok_p (cfun->decl))
4909 warning ("%Jfunction might be possible candidate for attribute `noreturn'",
4912 /* If we have a path to EXIT, then we do return. */
4913 if (TREE_THIS_VOLATILE (cfun->decl)
4914 && EXIT_BLOCK_PTR->pred != NULL)
4916 #ifdef USE_MAPPED_LOCATION
4917 location = UNKNOWN_LOCATION;
4921 for (e = EXIT_BLOCK_PTR->pred; e ; e = e->pred_next)
4923 last = last_stmt (e->src);
4924 if (TREE_CODE (last) == RETURN_EXPR
4925 #ifdef USE_MAPPED_LOCATION
4926 && (location = EXPR_LOCATION (last)) != UNKNOWN_LOCATION)
4928 && (locus = EXPR_LOCUS (last)) != NULL)
4932 #ifdef USE_MAPPED_LOCATION
4933 if (location == UNKNOWN_LOCATION)
4934 location = cfun->function_end_locus;
4935 warning ("%H`noreturn' function does return", &location);
4938 locus = &cfun->function_end_locus;
4939 warning ("%H`noreturn' function does return", locus);
4943 /* If we see "return;" in some basic block, then we do reach the end
4944 without returning a value. */
4945 else if (warn_return_type
4946 && EXIT_BLOCK_PTR->pred != NULL
4947 && !VOID_TYPE_P (TREE_TYPE (TREE_TYPE (cfun->decl))))
4949 for (e = EXIT_BLOCK_PTR->pred; e ; e = e->pred_next)
4951 tree last = last_stmt (e->src);
4952 if (TREE_CODE (last) == RETURN_EXPR
4953 && TREE_OPERAND (last, 0) == NULL)
4955 #ifdef USE_MAPPED_LOCATION
4956 location = EXPR_LOCATION (last);
4957 if (location == UNKNOWN_LOCATION)
4958 location = cfun->function_end_locus;
4959 warning ("%Hcontrol reaches end of non-void function", &location);
4961 locus = EXPR_LOCUS (last);
4963 locus = &cfun->function_end_locus;
4964 warning ("%Hcontrol reaches end of non-void function", locus);
4973 /* Given a basic block B which ends with a conditional and has
4974 precisely two successors, determine which of the edges is taken if
4975 the conditional is true and which is taken if the conditional is
4976 false. Set TRUE_EDGE and FALSE_EDGE appropriately. */
4979 extract_true_false_edges_from_block (basic_block b,
4985 if (e->flags & EDGE_TRUE_VALUE)
4988 *false_edge = e->succ_next;
4993 *true_edge = e->succ_next;
4997 struct tree_opt_pass pass_warn_function_return =
5001 execute_warn_function_return, /* execute */
5004 0, /* static_pass_number */
5006 PROP_cfg, /* properties_required */
5007 0, /* properties_provided */
5008 0, /* properties_destroyed */
5009 0, /* todo_flags_start */
5010 0 /* todo_flags_finish */
5013 #include "gt-tree-cfg.h"