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"
46 #include "cfglayout.h"
48 /* This file contains functions for building the Control Flow Graph (CFG)
49 for a function tree. */
51 /* Local declarations. */
53 /* Initial capacity for the basic block array. */
54 static const int initial_cfg_capacity = 20;
56 /* Mapping of labels to their associated blocks. This can greatly speed up
57 building of the CFG in code with lots of gotos. */
58 static GTY(()) varray_type label_to_block_map;
63 long num_merged_labels;
66 static struct cfg_stats_d cfg_stats;
68 /* Nonzero if we found a computed goto while building basic blocks. */
69 static bool found_computed_goto;
71 /* Basic blocks and flowgraphs. */
72 static basic_block create_bb (void *, void *, basic_block);
73 static void create_block_annotation (basic_block);
74 static void free_blocks_annotations (void);
75 static void clear_blocks_annotations (void);
76 static void make_blocks (tree);
77 static void factor_computed_gotos (void);
80 static void make_edges (void);
81 static void make_ctrl_stmt_edges (basic_block);
82 static void make_exit_edges (basic_block);
83 static void make_cond_expr_edges (basic_block);
84 static void make_switch_expr_edges (basic_block);
85 static void make_goto_expr_edges (basic_block);
86 static edge tree_redirect_edge_and_branch (edge, basic_block);
87 static edge tree_try_redirect_by_replacing_jump (edge, basic_block);
88 static void split_critical_edges (void);
90 /* Various helpers. */
91 static inline bool stmt_starts_bb_p (tree, tree);
92 static int tree_verify_flow_info (void);
93 static void tree_make_forwarder_block (edge);
94 static bool thread_jumps (void);
95 static bool tree_forwarder_block_p (basic_block);
96 static void bsi_commit_edge_inserts_1 (edge e);
97 static void tree_cfg2vcg (FILE *);
99 /* Flowgraph optimization and cleanup. */
100 static void tree_merge_blocks (basic_block, basic_block);
101 static bool tree_can_merge_blocks_p (basic_block, basic_block);
102 static void remove_bb (basic_block);
103 static bool cleanup_control_flow (void);
104 static bool cleanup_control_expr_graph (basic_block, block_stmt_iterator);
105 static edge find_taken_edge_cond_expr (basic_block, tree);
106 static edge find_taken_edge_switch_expr (basic_block, tree);
107 static tree find_case_label_for_value (tree, tree);
108 static bool phi_alternatives_equal (basic_block, edge, edge);
111 /*---------------------------------------------------------------------------
113 ---------------------------------------------------------------------------*/
115 /* Entry point to the CFG builder for trees. TP points to the list of
116 statements to be added to the flowgraph. */
119 build_tree_cfg (tree *tp)
121 /* Register specific tree functions. */
122 tree_register_cfg_hooks ();
124 /* Initialize rbi_pool. */
127 /* Initialize the basic block array. */
129 profile_status = PROFILE_ABSENT;
131 last_basic_block = 0;
132 VARRAY_BB_INIT (basic_block_info, initial_cfg_capacity, "basic_block_info");
133 memset ((void *) &cfg_stats, 0, sizeof (cfg_stats));
135 /* Build a mapping of labels to their associated blocks. */
136 VARRAY_BB_INIT (label_to_block_map, initial_cfg_capacity,
137 "label to block map");
139 ENTRY_BLOCK_PTR->next_bb = EXIT_BLOCK_PTR;
140 EXIT_BLOCK_PTR->prev_bb = ENTRY_BLOCK_PTR;
142 found_computed_goto = 0;
145 /* Computed gotos are hell to deal with, especially if there are
146 lots of them with a large number of destinations. So we factor
147 them to a common computed goto location before we build the
148 edge list. After we convert back to normal form, we will un-factor
149 the computed gotos since factoring introduces an unwanted jump. */
150 if (found_computed_goto)
151 factor_computed_gotos ();
153 /* Make sure there is always at least one block, even if its empty. */
154 if (n_basic_blocks == 0)
155 create_empty_bb (ENTRY_BLOCK_PTR);
157 create_block_annotation (ENTRY_BLOCK_PTR);
158 create_block_annotation (EXIT_BLOCK_PTR);
160 /* Adjust the size of the array. */
161 VARRAY_GROW (basic_block_info, n_basic_blocks);
163 /* To speed up statement iterator walks, we first purge dead labels. */
164 cleanup_dead_labels ();
166 /* Group case nodes to reduce the number of edges.
167 We do this after cleaning up dead labels because otherwise we miss
168 a lot of obvious case merging opportunities. */
169 group_case_labels ();
171 /* Create the edges of the flowgraph. */
174 /* Debugging dumps. */
176 /* Write the flowgraph to a VCG file. */
178 int local_dump_flags;
179 FILE *dump_file = dump_begin (TDI_vcg, &local_dump_flags);
182 tree_cfg2vcg (dump_file);
183 dump_end (TDI_vcg, dump_file);
187 /* Dump a textual representation of the flowgraph. */
189 dump_tree_cfg (dump_file, dump_flags);
193 execute_build_cfg (void)
195 build_tree_cfg (&DECL_SAVED_TREE (current_function_decl));
198 struct tree_opt_pass pass_build_cfg =
202 execute_build_cfg, /* execute */
205 0, /* static_pass_number */
206 TV_TREE_CFG, /* tv_id */
207 PROP_gimple_leh, /* properties_required */
208 PROP_cfg, /* properties_provided */
209 0, /* properties_destroyed */
210 0, /* todo_flags_start */
211 TODO_verify_stmts, /* todo_flags_finish */
215 /* Search the CFG for any computed gotos. If found, factor them to a
216 common computed goto site. Also record the location of that site so
217 that we can un-factor the gotos after we have converted back to
221 factor_computed_gotos (void)
224 tree factored_label_decl = NULL;
226 tree factored_computed_goto_label = NULL;
227 tree factored_computed_goto = NULL;
229 /* We know there are one or more computed gotos in this function.
230 Examine the last statement in each basic block to see if the block
231 ends with a computed goto. */
235 block_stmt_iterator bsi = bsi_last (bb);
240 last = bsi_stmt (bsi);
242 /* Ignore the computed goto we create when we factor the original
244 if (last == factored_computed_goto)
247 /* If the last statement is a computed goto, factor it. */
248 if (computed_goto_p (last))
252 /* The first time we find a computed goto we need to create
253 the factored goto block and the variable each original
254 computed goto will use for their goto destination. */
255 if (! factored_computed_goto)
257 basic_block new_bb = create_empty_bb (bb);
258 block_stmt_iterator new_bsi = bsi_start (new_bb);
260 /* Create the destination of the factored goto. Each original
261 computed goto will put its desired destination into this
262 variable and jump to the label we create immediately
264 var = create_tmp_var (ptr_type_node, "gotovar");
266 /* Build a label for the new block which will contain the
267 factored computed goto. */
268 factored_label_decl = create_artificial_label ();
269 factored_computed_goto_label
270 = build1 (LABEL_EXPR, void_type_node, factored_label_decl);
271 bsi_insert_after (&new_bsi, factored_computed_goto_label,
274 /* Build our new computed goto. */
275 factored_computed_goto = build1 (GOTO_EXPR, void_type_node, var);
276 bsi_insert_after (&new_bsi, factored_computed_goto,
280 /* Copy the original computed goto's destination into VAR. */
281 assignment = build (MODIFY_EXPR, ptr_type_node,
282 var, GOTO_DESTINATION (last));
283 bsi_insert_before (&bsi, assignment, BSI_SAME_STMT);
285 /* And re-vector the computed goto to the new destination. */
286 GOTO_DESTINATION (last) = factored_label_decl;
292 /* Create annotations for a single basic block. */
295 create_block_annotation (basic_block bb)
297 /* Verify that the tree_annotations field is clear. */
298 gcc_assert (!bb->tree_annotations);
299 bb->tree_annotations = ggc_alloc_cleared (sizeof (struct bb_ann_d));
303 /* Free the annotations for all the basic blocks. */
305 static void free_blocks_annotations (void)
307 clear_blocks_annotations ();
311 /* Clear the annotations for all the basic blocks. */
314 clear_blocks_annotations (void)
318 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb)
319 bb->tree_annotations = NULL;
323 /* Build a flowgraph for the statement_list STMT_LIST. */
326 make_blocks (tree stmt_list)
328 tree_stmt_iterator i = tsi_start (stmt_list);
330 bool start_new_block = true;
331 bool first_stmt_of_list = true;
332 basic_block bb = ENTRY_BLOCK_PTR;
334 while (!tsi_end_p (i))
341 /* If the statement starts a new basic block or if we have determined
342 in a previous pass that we need to create a new block for STMT, do
344 if (start_new_block || stmt_starts_bb_p (stmt, prev_stmt))
346 if (!first_stmt_of_list)
347 stmt_list = tsi_split_statement_list_before (&i);
348 bb = create_basic_block (stmt_list, NULL, bb);
349 start_new_block = false;
352 /* Now add STMT to BB and create the subgraphs for special statement
354 set_bb_for_stmt (stmt, bb);
356 if (computed_goto_p (stmt))
357 found_computed_goto = true;
359 /* If STMT is a basic block terminator, set START_NEW_BLOCK for the
361 if (stmt_ends_bb_p (stmt))
362 start_new_block = true;
365 first_stmt_of_list = false;
370 /* Create and return a new empty basic block after bb AFTER. */
373 create_bb (void *h, void *e, basic_block after)
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 (EDGE_COUNT (bb->succs) == 0)
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);
465 switch (TREE_CODE (last))
468 make_goto_expr_edges (bb);
472 make_edge (bb, EXIT_BLOCK_PTR, 0);
476 make_cond_expr_edges (bb);
480 make_switch_expr_edges (bb);
484 make_eh_edges (last);
485 /* Yet another NORETURN hack. */
486 if (EDGE_COUNT (bb->succs) == 0)
487 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
496 /* Create exit edges for statements in block BB that alter the flow of
497 control. Statements that alter the control flow are 'goto', 'return'
498 and calls to non-returning functions. */
501 make_exit_edges (basic_block bb)
503 tree last = last_stmt (bb), op;
506 switch (TREE_CODE (last))
509 /* If this function receives a nonlocal goto, then we need to
510 make edges from this call site to all the nonlocal goto
512 if (TREE_SIDE_EFFECTS (last)
513 && current_function_has_nonlocal_label)
514 make_goto_expr_edges (bb);
516 /* If this statement has reachable exception handlers, then
517 create abnormal edges to them. */
518 make_eh_edges (last);
520 /* Some calls are known not to return. For such calls we create
523 We really need to revamp how we build edges so that it's not
524 such a bloody pain to avoid creating edges for this case since
525 all we do is remove these edges when we're done building the
527 if (call_expr_flags (last) & (ECF_NORETURN | ECF_LONGJMP))
529 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
533 /* Don't forget the fall-thru edge. */
534 make_edge (bb, bb->next_bb, EDGE_FALLTHRU);
538 /* A MODIFY_EXPR may have a CALL_EXPR on its RHS and the CALL_EXPR
539 may have an abnormal edge. Search the RHS for this case and
540 create any required edges. */
541 op = get_call_expr_in (last);
542 if (op && TREE_SIDE_EFFECTS (op)
543 && current_function_has_nonlocal_label)
544 make_goto_expr_edges (bb);
546 make_eh_edges (last);
547 make_edge (bb, bb->next_bb, EDGE_FALLTHRU);
556 /* Create the edges for a COND_EXPR starting at block BB.
557 At this point, both clauses must contain only simple gotos. */
560 make_cond_expr_edges (basic_block bb)
562 tree entry = last_stmt (bb);
563 basic_block then_bb, else_bb;
564 tree then_label, else_label;
567 gcc_assert (TREE_CODE (entry) == COND_EXPR);
569 /* Entry basic blocks for each component. */
570 then_label = GOTO_DESTINATION (COND_EXPR_THEN (entry));
571 else_label = GOTO_DESTINATION (COND_EXPR_ELSE (entry));
572 then_bb = label_to_block (then_label);
573 else_bb = label_to_block (else_label);
575 make_edge (bb, then_bb, EDGE_TRUE_VALUE);
576 make_edge (bb, else_bb, EDGE_FALSE_VALUE);
580 /* Create the edges for a SWITCH_EXPR starting at block BB.
581 At this point, the switch body has been lowered and the
582 SWITCH_LABELS filled in, so this is in effect a multi-way branch. */
585 make_switch_expr_edges (basic_block bb)
587 tree entry = last_stmt (bb);
591 vec = SWITCH_LABELS (entry);
592 n = TREE_VEC_LENGTH (vec);
594 for (i = 0; i < n; ++i)
596 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
597 basic_block label_bb = label_to_block (lab);
598 make_edge (bb, label_bb, 0);
603 /* Return the basic block holding label DEST. */
606 label_to_block (tree dest)
608 int uid = LABEL_DECL_UID (dest);
610 /* We would die hard when faced by undefined label. Emit label to
611 very first basic block. This will hopefully make even the dataflow
612 and undefined variable warnings quite right. */
613 if ((errorcount || sorrycount) && uid < 0)
615 block_stmt_iterator bsi = bsi_start (BASIC_BLOCK (0));
618 stmt = build1 (LABEL_EXPR, void_type_node, dest);
619 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
620 uid = LABEL_DECL_UID (dest);
622 return VARRAY_BB (label_to_block_map, uid);
626 /* Create edges for a goto statement at block BB. */
629 make_goto_expr_edges (basic_block bb)
632 basic_block target_bb;
634 block_stmt_iterator last = bsi_last (bb);
636 goto_t = bsi_stmt (last);
638 /* If the last statement is not a GOTO (i.e., it is a RETURN_EXPR,
639 CALL_EXPR or MODIFY_EXPR), then the edge is an abnormal edge resulting
640 from a nonlocal goto. */
641 if (TREE_CODE (goto_t) != GOTO_EXPR)
643 dest = error_mark_node;
648 dest = GOTO_DESTINATION (goto_t);
651 /* A GOTO to a local label creates normal edges. */
652 if (simple_goto_p (goto_t))
654 edge e = make_edge (bb, label_to_block (dest), EDGE_FALLTHRU);
655 #ifdef USE_MAPPED_LOCATION
656 e->goto_locus = EXPR_LOCATION (goto_t);
658 e->goto_locus = EXPR_LOCUS (goto_t);
664 /* Nothing more to do for nonlocal gotos. */
665 if (TREE_CODE (dest) == LABEL_DECL)
668 /* Computed gotos remain. */
671 /* Look for the block starting with the destination label. In the
672 case of a computed goto, make an edge to any label block we find
674 FOR_EACH_BB (target_bb)
676 block_stmt_iterator bsi;
678 for (bsi = bsi_start (target_bb); !bsi_end_p (bsi); bsi_next (&bsi))
680 tree target = bsi_stmt (bsi);
682 if (TREE_CODE (target) != LABEL_EXPR)
686 /* Computed GOTOs. Make an edge to every label block that has
687 been marked as a potential target for a computed goto. */
688 (FORCED_LABEL (LABEL_EXPR_LABEL (target)) && for_call == 0)
689 /* Nonlocal GOTO target. Make an edge to every label block
690 that has been marked as a potential target for a nonlocal
692 || (DECL_NONLOCAL (LABEL_EXPR_LABEL (target)) && for_call == 1))
694 make_edge (bb, target_bb, EDGE_ABNORMAL);
700 /* Degenerate case of computed goto with no labels. */
701 if (!for_call && EDGE_COUNT (bb->succs) == 0)
702 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
706 /*---------------------------------------------------------------------------
708 ---------------------------------------------------------------------------*/
710 /* Remove unreachable blocks and other miscellaneous clean up work. */
713 cleanup_tree_cfg (void)
715 bool something_changed = true;
718 timevar_push (TV_TREE_CLEANUP_CFG);
720 retval = cleanup_control_flow ();
721 retval |= delete_unreachable_blocks ();
723 /* thread_jumps() sometimes leaves further transformation
724 opportunities for itself, so iterate on it until nothing
726 while (something_changed)
728 something_changed = thread_jumps ();
730 /* delete_unreachable_blocks() does its job only when
731 thread_jumps() produces more unreachable blocks. */
732 if (something_changed)
733 delete_unreachable_blocks ();
735 retval |= something_changed;
738 #ifdef ENABLE_CHECKING
741 gcc_assert (!cleanup_control_flow ());
742 gcc_assert (!delete_unreachable_blocks ());
746 /* Merging the blocks creates no new opportunities for the other
747 optimizations, so do it here. */
752 #ifdef ENABLE_CHECKING
755 timevar_pop (TV_TREE_CLEANUP_CFG);
760 /* Cleanup useless labels in basic blocks. This is something we wish
761 to do early because it allows us to group case labels before creating
762 the edges for the CFG, and it speeds up block statement iterators in
764 We only run this pass once, running it more than once is probably not
767 /* A map from basic block index to the leading label of that block. */
768 static tree *label_for_bb;
770 /* Callback for for_each_eh_region. Helper for cleanup_dead_labels. */
772 update_eh_label (struct eh_region *region)
774 tree old_label = get_eh_region_tree_label (region);
778 basic_block bb = label_to_block (old_label);
780 /* ??? After optimizing, there may be EH regions with labels
781 that have already been removed from the function body, so
782 there is no basic block for them. */
786 new_label = label_for_bb[bb->index];
787 set_eh_region_tree_label (region, new_label);
791 /* Given LABEL return the first label in the same basic block. */
793 main_block_label (tree label)
795 basic_block bb = label_to_block (label);
797 /* label_to_block possibly inserted undefined label into the chain. */
798 if (!label_for_bb[bb->index])
799 label_for_bb[bb->index] = label;
800 return label_for_bb[bb->index];
803 /* Cleanup redundant labels. This is a three-steo process:
804 1) Find the leading label for each block.
805 2) Redirect all references to labels to the leading labels.
806 3) Cleanup all useless labels. */
809 cleanup_dead_labels (void)
812 label_for_bb = xcalloc (last_basic_block, sizeof (tree));
814 /* Find a suitable label for each block. We use the first user-defined
815 label is there is one, or otherwise just the first label we see. */
818 block_stmt_iterator i;
820 for (i = bsi_start (bb); !bsi_end_p (i); bsi_next (&i))
822 tree label, stmt = bsi_stmt (i);
824 if (TREE_CODE (stmt) != LABEL_EXPR)
827 label = LABEL_EXPR_LABEL (stmt);
829 /* If we have not yet seen a label for the current block,
830 remember this one and see if there are more labels. */
831 if (! label_for_bb[bb->index])
833 label_for_bb[bb->index] = label;
837 /* If we did see a label for the current block already, but it
838 is an artificially created label, replace it if the current
839 label is a user defined label. */
840 if (! DECL_ARTIFICIAL (label)
841 && DECL_ARTIFICIAL (label_for_bb[bb->index]))
843 label_for_bb[bb->index] = label;
849 /* Now redirect all jumps/branches to the selected label.
850 First do so for each block ending in a control statement. */
853 tree stmt = last_stmt (bb);
857 switch (TREE_CODE (stmt))
861 tree true_branch, false_branch;
863 true_branch = COND_EXPR_THEN (stmt);
864 false_branch = COND_EXPR_ELSE (stmt);
866 GOTO_DESTINATION (true_branch)
867 = main_block_label (GOTO_DESTINATION (true_branch));
868 GOTO_DESTINATION (false_branch)
869 = main_block_label (GOTO_DESTINATION (false_branch));
877 tree vec = SWITCH_LABELS (stmt);
878 size_t n = TREE_VEC_LENGTH (vec);
880 /* Replace all destination labels. */
881 for (i = 0; i < n; ++i)
882 CASE_LABEL (TREE_VEC_ELT (vec, i))
883 = main_block_label (CASE_LABEL (TREE_VEC_ELT (vec, i)));
888 /* We have to handle GOTO_EXPRs until they're removed, and we don't
889 remove them until after we've created the CFG edges. */
891 if (! computed_goto_p (stmt))
893 GOTO_DESTINATION (stmt)
894 = main_block_label (GOTO_DESTINATION (stmt));
903 for_each_eh_region (update_eh_label);
905 /* Finally, purge dead labels. All user-defined labels and labels that
906 can be the target of non-local gotos are preserved. */
909 block_stmt_iterator i;
910 tree label_for_this_bb = label_for_bb[bb->index];
912 if (! label_for_this_bb)
915 for (i = bsi_start (bb); !bsi_end_p (i); )
917 tree label, stmt = bsi_stmt (i);
919 if (TREE_CODE (stmt) != LABEL_EXPR)
922 label = LABEL_EXPR_LABEL (stmt);
924 if (label == label_for_this_bb
925 || ! DECL_ARTIFICIAL (label)
926 || DECL_NONLOCAL (label))
936 /* Look for blocks ending in a multiway branch (a SWITCH_EXPR in GIMPLE),
937 and scan the sorted vector of cases. Combine the ones jumping to the
939 Eg. three separate entries 1: 2: 3: become one entry 1..3: */
942 group_case_labels (void)
948 tree stmt = last_stmt (bb);
949 if (stmt && TREE_CODE (stmt) == SWITCH_EXPR)
951 tree labels = SWITCH_LABELS (stmt);
952 int old_size = TREE_VEC_LENGTH (labels);
953 int i, j, new_size = old_size;
954 tree default_case = TREE_VEC_ELT (labels, old_size - 1);
957 /* The default lable is always the last case in a switch
958 statement after gimplification. */
959 default_label = CASE_LABEL (default_case);
961 /* Look for possible opportunities to merge cases.
962 Ignore the last element of the label vector because it
963 must be the default case. */
965 while (i < old_size - 2)
967 tree base_case, base_label, base_high, type;
968 base_case = TREE_VEC_ELT (labels, i);
970 gcc_assert (base_case);
971 base_label = CASE_LABEL (base_case);
973 /* Discard cases that have the same destination as the
975 if (base_label == default_label)
977 TREE_VEC_ELT (labels, i) = NULL_TREE;
983 type = TREE_TYPE (CASE_LOW (base_case));
984 base_high = CASE_HIGH (base_case) ?
985 CASE_HIGH (base_case) : CASE_LOW (base_case);
987 /* Try to merge case labels. Break out when we reach the end
988 of the label vector or when we cannot merge the next case
989 label with the current one. */
990 while (i < old_size - 2)
992 tree merge_case = TREE_VEC_ELT (labels, ++i);
993 tree merge_label = CASE_LABEL (merge_case);
994 tree t = int_const_binop (PLUS_EXPR, base_high,
995 integer_one_node, 1);
997 /* Merge the cases if they jump to the same place,
998 and their ranges are consecutive. */
999 if (merge_label == base_label
1000 && tree_int_cst_equal (CASE_LOW (merge_case), t))
1002 base_high = CASE_HIGH (merge_case) ?
1003 CASE_HIGH (merge_case) : CASE_LOW (merge_case);
1004 CASE_HIGH (base_case) = base_high;
1005 TREE_VEC_ELT (labels, i) = NULL_TREE;
1013 /* Compress the case labels in the label vector, and adjust the
1014 length of the vector. */
1015 for (i = 0, j = 0; i < new_size; i++)
1017 while (! TREE_VEC_ELT (labels, j))
1019 TREE_VEC_ELT (labels, i) = TREE_VEC_ELT (labels, j++);
1021 TREE_VEC_LENGTH (labels) = new_size;
1026 /* Checks whether we can merge block B into block A. */
1029 tree_can_merge_blocks_p (basic_block a, basic_block b)
1032 block_stmt_iterator bsi;
1034 if (EDGE_COUNT (a->succs) != 1)
1037 if (EDGE_SUCC (a, 0)->flags & EDGE_ABNORMAL)
1040 if (EDGE_SUCC (a, 0)->dest != b)
1043 if (b == EXIT_BLOCK_PTR)
1046 if (EDGE_COUNT (b->preds) > 1)
1049 /* If A ends by a statement causing exceptions or something similar, we
1050 cannot merge the blocks. */
1051 stmt = last_stmt (a);
1052 if (stmt && stmt_ends_bb_p (stmt))
1055 /* Do not allow a block with only a non-local label to be merged. */
1056 if (stmt && TREE_CODE (stmt) == LABEL_EXPR
1057 && DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)))
1060 /* There may be no phi nodes at the start of b. Most of these degenerate
1061 phi nodes should be cleaned up by kill_redundant_phi_nodes. */
1065 /* Do not remove user labels. */
1066 for (bsi = bsi_start (b); !bsi_end_p (bsi); bsi_next (&bsi))
1068 stmt = bsi_stmt (bsi);
1069 if (TREE_CODE (stmt) != LABEL_EXPR)
1071 if (!DECL_ARTIFICIAL (LABEL_EXPR_LABEL (stmt)))
1079 /* Merge block B into block A. */
1082 tree_merge_blocks (basic_block a, basic_block b)
1084 block_stmt_iterator bsi;
1085 tree_stmt_iterator last;
1088 fprintf (dump_file, "Merging blocks %d and %d\n", a->index, b->index);
1090 /* Ensure that B follows A. */
1091 move_block_after (b, a);
1093 gcc_assert (EDGE_SUCC (a, 0)->flags & EDGE_FALLTHRU);
1094 gcc_assert (!last_stmt (a) || !stmt_ends_bb_p (last_stmt (a)));
1096 /* Remove labels from B and set bb_for_stmt to A for other statements. */
1097 for (bsi = bsi_start (b); !bsi_end_p (bsi);)
1099 if (TREE_CODE (bsi_stmt (bsi)) == LABEL_EXPR)
1103 set_bb_for_stmt (bsi_stmt (bsi), a);
1108 /* Merge the chains. */
1109 last = tsi_last (a->stmt_list);
1110 tsi_link_after (&last, b->stmt_list, TSI_NEW_STMT);
1111 b->stmt_list = NULL;
1115 /* Walk the function tree removing unnecessary statements.
1117 * Empty statement nodes are removed
1119 * Unnecessary TRY_FINALLY and TRY_CATCH blocks are removed
1121 * Unnecessary COND_EXPRs are removed
1123 * Some unnecessary BIND_EXPRs are removed
1125 Clearly more work could be done. The trick is doing the analysis
1126 and removal fast enough to be a net improvement in compile times.
1128 Note that when we remove a control structure such as a COND_EXPR
1129 BIND_EXPR, or TRY block, we will need to repeat this optimization pass
1130 to ensure we eliminate all the useless code. */
1141 static void remove_useless_stmts_1 (tree *, struct rus_data *);
1144 remove_useless_stmts_warn_notreached (tree stmt)
1146 if (EXPR_HAS_LOCATION (stmt))
1148 location_t loc = EXPR_LOCATION (stmt);
1149 warning ("%Hwill never be executed", &loc);
1153 switch (TREE_CODE (stmt))
1155 case STATEMENT_LIST:
1157 tree_stmt_iterator i;
1158 for (i = tsi_start (stmt); !tsi_end_p (i); tsi_next (&i))
1159 if (remove_useless_stmts_warn_notreached (tsi_stmt (i)))
1165 if (remove_useless_stmts_warn_notreached (COND_EXPR_COND (stmt)))
1167 if (remove_useless_stmts_warn_notreached (COND_EXPR_THEN (stmt)))
1169 if (remove_useless_stmts_warn_notreached (COND_EXPR_ELSE (stmt)))
1173 case TRY_FINALLY_EXPR:
1174 case TRY_CATCH_EXPR:
1175 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt, 0)))
1177 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt, 1)))
1182 return remove_useless_stmts_warn_notreached (CATCH_BODY (stmt));
1183 case EH_FILTER_EXPR:
1184 return remove_useless_stmts_warn_notreached (EH_FILTER_FAILURE (stmt));
1186 return remove_useless_stmts_warn_notreached (BIND_EXPR_BLOCK (stmt));
1189 /* Not a live container. */
1197 remove_useless_stmts_cond (tree *stmt_p, struct rus_data *data)
1199 tree then_clause, else_clause, cond;
1200 bool save_has_label, then_has_label, else_has_label;
1202 save_has_label = data->has_label;
1203 data->has_label = false;
1204 data->last_goto = NULL;
1206 remove_useless_stmts_1 (&COND_EXPR_THEN (*stmt_p), data);
1208 then_has_label = data->has_label;
1209 data->has_label = false;
1210 data->last_goto = NULL;
1212 remove_useless_stmts_1 (&COND_EXPR_ELSE (*stmt_p), data);
1214 else_has_label = data->has_label;
1215 data->has_label = save_has_label | then_has_label | else_has_label;
1218 then_clause = COND_EXPR_THEN (*stmt_p);
1219 else_clause = COND_EXPR_ELSE (*stmt_p);
1220 cond = COND_EXPR_COND (*stmt_p);
1222 /* If neither arm does anything at all, we can remove the whole IF. */
1223 if (!TREE_SIDE_EFFECTS (then_clause) && !TREE_SIDE_EFFECTS (else_clause))
1225 *stmt_p = build_empty_stmt ();
1226 data->repeat = true;
1229 /* If there are no reachable statements in an arm, then we can
1230 zap the entire conditional. */
1231 else if (integer_nonzerop (cond) && !else_has_label)
1233 if (warn_notreached)
1234 remove_useless_stmts_warn_notreached (else_clause);
1235 *stmt_p = then_clause;
1236 data->repeat = true;
1238 else if (integer_zerop (cond) && !then_has_label)
1240 if (warn_notreached)
1241 remove_useless_stmts_warn_notreached (then_clause);
1242 *stmt_p = else_clause;
1243 data->repeat = true;
1246 /* Check a couple of simple things on then/else with single stmts. */
1249 tree then_stmt = expr_only (then_clause);
1250 tree else_stmt = expr_only (else_clause);
1252 /* Notice branches to a common destination. */
1253 if (then_stmt && else_stmt
1254 && TREE_CODE (then_stmt) == GOTO_EXPR
1255 && TREE_CODE (else_stmt) == GOTO_EXPR
1256 && (GOTO_DESTINATION (then_stmt) == GOTO_DESTINATION (else_stmt)))
1258 *stmt_p = then_stmt;
1259 data->repeat = true;
1262 /* If the THEN/ELSE clause merely assigns a value to a variable or
1263 parameter which is already known to contain that value, then
1264 remove the useless THEN/ELSE clause. */
1265 else if (TREE_CODE (cond) == VAR_DECL || TREE_CODE (cond) == PARM_DECL)
1268 && TREE_CODE (else_stmt) == MODIFY_EXPR
1269 && TREE_OPERAND (else_stmt, 0) == cond
1270 && integer_zerop (TREE_OPERAND (else_stmt, 1)))
1271 COND_EXPR_ELSE (*stmt_p) = alloc_stmt_list ();
1273 else if ((TREE_CODE (cond) == EQ_EXPR || TREE_CODE (cond) == NE_EXPR)
1274 && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL
1275 || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL)
1276 && TREE_CONSTANT (TREE_OPERAND (cond, 1)))
1278 tree stmt = (TREE_CODE (cond) == EQ_EXPR
1279 ? then_stmt : else_stmt);
1280 tree *location = (TREE_CODE (cond) == EQ_EXPR
1281 ? &COND_EXPR_THEN (*stmt_p)
1282 : &COND_EXPR_ELSE (*stmt_p));
1285 && TREE_CODE (stmt) == MODIFY_EXPR
1286 && TREE_OPERAND (stmt, 0) == TREE_OPERAND (cond, 0)
1287 && TREE_OPERAND (stmt, 1) == TREE_OPERAND (cond, 1))
1288 *location = alloc_stmt_list ();
1292 /* Protect GOTOs in the arm of COND_EXPRs from being removed. They
1293 would be re-introduced during lowering. */
1294 data->last_goto = NULL;
1299 remove_useless_stmts_tf (tree *stmt_p, struct rus_data *data)
1301 bool save_may_branch, save_may_throw;
1302 bool this_may_branch, this_may_throw;
1304 /* Collect may_branch and may_throw information for the body only. */
1305 save_may_branch = data->may_branch;
1306 save_may_throw = data->may_throw;
1307 data->may_branch = false;
1308 data->may_throw = false;
1309 data->last_goto = NULL;
1311 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 0), data);
1313 this_may_branch = data->may_branch;
1314 this_may_throw = data->may_throw;
1315 data->may_branch |= save_may_branch;
1316 data->may_throw |= save_may_throw;
1317 data->last_goto = NULL;
1319 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 1), data);
1321 /* If the body is empty, then we can emit the FINALLY block without
1322 the enclosing TRY_FINALLY_EXPR. */
1323 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 0)))
1325 *stmt_p = TREE_OPERAND (*stmt_p, 1);
1326 data->repeat = true;
1329 /* If the handler is empty, then we can emit the TRY block without
1330 the enclosing TRY_FINALLY_EXPR. */
1331 else if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 1)))
1333 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1334 data->repeat = true;
1337 /* If the body neither throws, nor branches, then we can safely
1338 string the TRY and FINALLY blocks together. */
1339 else if (!this_may_branch && !this_may_throw)
1341 tree stmt = *stmt_p;
1342 *stmt_p = TREE_OPERAND (stmt, 0);
1343 append_to_statement_list (TREE_OPERAND (stmt, 1), stmt_p);
1344 data->repeat = true;
1350 remove_useless_stmts_tc (tree *stmt_p, struct rus_data *data)
1352 bool save_may_throw, this_may_throw;
1353 tree_stmt_iterator i;
1356 /* Collect may_throw information for the body only. */
1357 save_may_throw = data->may_throw;
1358 data->may_throw = false;
1359 data->last_goto = NULL;
1361 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 0), data);
1363 this_may_throw = data->may_throw;
1364 data->may_throw = save_may_throw;
1366 /* If the body cannot throw, then we can drop the entire TRY_CATCH_EXPR. */
1367 if (!this_may_throw)
1369 if (warn_notreached)
1370 remove_useless_stmts_warn_notreached (TREE_OPERAND (*stmt_p, 1));
1371 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1372 data->repeat = true;
1376 /* Process the catch clause specially. We may be able to tell that
1377 no exceptions propagate past this point. */
1379 this_may_throw = true;
1380 i = tsi_start (TREE_OPERAND (*stmt_p, 1));
1381 stmt = tsi_stmt (i);
1382 data->last_goto = NULL;
1384 switch (TREE_CODE (stmt))
1387 for (; !tsi_end_p (i); tsi_next (&i))
1389 stmt = tsi_stmt (i);
1390 /* If we catch all exceptions, then the body does not
1391 propagate exceptions past this point. */
1392 if (CATCH_TYPES (stmt) == NULL)
1393 this_may_throw = false;
1394 data->last_goto = NULL;
1395 remove_useless_stmts_1 (&CATCH_BODY (stmt), data);
1399 case EH_FILTER_EXPR:
1400 if (EH_FILTER_MUST_NOT_THROW (stmt))
1401 this_may_throw = false;
1402 else if (EH_FILTER_TYPES (stmt) == NULL)
1403 this_may_throw = false;
1404 remove_useless_stmts_1 (&EH_FILTER_FAILURE (stmt), data);
1408 /* Otherwise this is a cleanup. */
1409 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 1), data);
1411 /* If the cleanup is empty, then we can emit the TRY block without
1412 the enclosing TRY_CATCH_EXPR. */
1413 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 1)))
1415 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1416 data->repeat = true;
1420 data->may_throw |= this_may_throw;
1425 remove_useless_stmts_bind (tree *stmt_p, struct rus_data *data)
1429 /* First remove anything underneath the BIND_EXPR. */
1430 remove_useless_stmts_1 (&BIND_EXPR_BODY (*stmt_p), data);
1432 /* If the BIND_EXPR has no variables, then we can pull everything
1433 up one level and remove the BIND_EXPR, unless this is the toplevel
1434 BIND_EXPR for the current function or an inlined function.
1436 When this situation occurs we will want to apply this
1437 optimization again. */
1438 block = BIND_EXPR_BLOCK (*stmt_p);
1439 if (BIND_EXPR_VARS (*stmt_p) == NULL_TREE
1440 && *stmt_p != DECL_SAVED_TREE (current_function_decl)
1442 || ! BLOCK_ABSTRACT_ORIGIN (block)
1443 || (TREE_CODE (BLOCK_ABSTRACT_ORIGIN (block))
1446 *stmt_p = BIND_EXPR_BODY (*stmt_p);
1447 data->repeat = true;
1453 remove_useless_stmts_goto (tree *stmt_p, struct rus_data *data)
1455 tree dest = GOTO_DESTINATION (*stmt_p);
1457 data->may_branch = true;
1458 data->last_goto = NULL;
1460 /* Record the last goto expr, so that we can delete it if unnecessary. */
1461 if (TREE_CODE (dest) == LABEL_DECL)
1462 data->last_goto = stmt_p;
1467 remove_useless_stmts_label (tree *stmt_p, struct rus_data *data)
1469 tree label = LABEL_EXPR_LABEL (*stmt_p);
1471 data->has_label = true;
1473 /* We do want to jump across non-local label receiver code. */
1474 if (DECL_NONLOCAL (label))
1475 data->last_goto = NULL;
1477 else if (data->last_goto && GOTO_DESTINATION (*data->last_goto) == label)
1479 *data->last_goto = build_empty_stmt ();
1480 data->repeat = true;
1483 /* ??? Add something here to delete unused labels. */
1487 /* If the function is "const" or "pure", then clear TREE_SIDE_EFFECTS on its
1488 decl. This allows us to eliminate redundant or useless
1489 calls to "const" functions.
1491 Gimplifier already does the same operation, but we may notice functions
1492 being const and pure once their calls has been gimplified, so we need
1493 to update the flag. */
1496 update_call_expr_flags (tree call)
1498 tree decl = get_callee_fndecl (call);
1501 if (call_expr_flags (call) & (ECF_CONST | ECF_PURE))
1502 TREE_SIDE_EFFECTS (call) = 0;
1503 if (TREE_NOTHROW (decl))
1504 TREE_NOTHROW (call) = 1;
1508 /* T is CALL_EXPR. Set current_function_calls_* flags. */
1511 notice_special_calls (tree t)
1513 int flags = call_expr_flags (t);
1515 if (flags & ECF_MAY_BE_ALLOCA)
1516 current_function_calls_alloca = true;
1517 if (flags & ECF_RETURNS_TWICE)
1518 current_function_calls_setjmp = true;
1522 /* Clear flags set by notice_special_calls. Used by dead code removal
1523 to update the flags. */
1526 clear_special_calls (void)
1528 current_function_calls_alloca = false;
1529 current_function_calls_setjmp = false;
1534 remove_useless_stmts_1 (tree *tp, struct rus_data *data)
1538 switch (TREE_CODE (t))
1541 remove_useless_stmts_cond (tp, data);
1544 case TRY_FINALLY_EXPR:
1545 remove_useless_stmts_tf (tp, data);
1548 case TRY_CATCH_EXPR:
1549 remove_useless_stmts_tc (tp, data);
1553 remove_useless_stmts_bind (tp, data);
1557 remove_useless_stmts_goto (tp, data);
1561 remove_useless_stmts_label (tp, data);
1566 data->last_goto = NULL;
1567 data->may_branch = true;
1572 data->last_goto = NULL;
1573 notice_special_calls (t);
1574 update_call_expr_flags (t);
1575 if (tree_could_throw_p (t))
1576 data->may_throw = true;
1580 data->last_goto = NULL;
1582 op = get_call_expr_in (t);
1585 update_call_expr_flags (op);
1586 notice_special_calls (op);
1588 if (tree_could_throw_p (t))
1589 data->may_throw = true;
1592 case STATEMENT_LIST:
1594 tree_stmt_iterator i = tsi_start (t);
1595 while (!tsi_end_p (i))
1598 if (IS_EMPTY_STMT (t))
1604 remove_useless_stmts_1 (tsi_stmt_ptr (i), data);
1607 if (TREE_CODE (t) == STATEMENT_LIST)
1609 tsi_link_before (&i, t, TSI_SAME_STMT);
1619 data->last_goto = NULL;
1623 data->last_goto = NULL;
1629 remove_useless_stmts (void)
1631 struct rus_data data;
1633 clear_special_calls ();
1637 memset (&data, 0, sizeof (data));
1638 remove_useless_stmts_1 (&DECL_SAVED_TREE (current_function_decl), &data);
1640 while (data.repeat);
1644 struct tree_opt_pass pass_remove_useless_stmts =
1646 "useless", /* name */
1648 remove_useless_stmts, /* execute */
1651 0, /* static_pass_number */
1653 PROP_gimple_any, /* properties_required */
1654 0, /* properties_provided */
1655 0, /* properties_destroyed */
1656 0, /* todo_flags_start */
1657 TODO_dump_func, /* todo_flags_finish */
1662 /* Remove obviously useless statements in basic block BB. */
1665 cfg_remove_useless_stmts_bb (basic_block bb)
1667 block_stmt_iterator bsi;
1668 tree stmt = NULL_TREE;
1669 tree cond, var = NULL_TREE, val = NULL_TREE;
1670 struct var_ann_d *ann;
1672 /* Check whether we come here from a condition, and if so, get the
1674 if (EDGE_COUNT (bb->preds) != 1
1675 || !(EDGE_PRED (bb, 0)->flags & (EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
1678 cond = COND_EXPR_COND (last_stmt (EDGE_PRED (bb, 0)->src));
1680 if (TREE_CODE (cond) == VAR_DECL || TREE_CODE (cond) == PARM_DECL)
1683 val = (EDGE_PRED (bb, 0)->flags & EDGE_FALSE_VALUE
1684 ? boolean_false_node : boolean_true_node);
1686 else if (TREE_CODE (cond) == TRUTH_NOT_EXPR
1687 && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL
1688 || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL))
1690 var = TREE_OPERAND (cond, 0);
1691 val = (EDGE_PRED (bb, 0)->flags & EDGE_FALSE_VALUE
1692 ? boolean_true_node : boolean_false_node);
1696 if (EDGE_PRED (bb, 0)->flags & EDGE_FALSE_VALUE)
1697 cond = invert_truthvalue (cond);
1698 if (TREE_CODE (cond) == EQ_EXPR
1699 && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL
1700 || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL)
1701 && (TREE_CODE (TREE_OPERAND (cond, 1)) == VAR_DECL
1702 || TREE_CODE (TREE_OPERAND (cond, 1)) == PARM_DECL
1703 || TREE_CONSTANT (TREE_OPERAND (cond, 1))))
1705 var = TREE_OPERAND (cond, 0);
1706 val = TREE_OPERAND (cond, 1);
1712 /* Only work for normal local variables. */
1713 ann = var_ann (var);
1716 || TREE_ADDRESSABLE (var))
1719 if (! TREE_CONSTANT (val))
1721 ann = var_ann (val);
1724 || TREE_ADDRESSABLE (val))
1728 /* Ignore floating point variables, since comparison behaves weird for
1730 if (FLOAT_TYPE_P (TREE_TYPE (var)))
1733 for (bsi = bsi_start (bb); !bsi_end_p (bsi);)
1735 stmt = bsi_stmt (bsi);
1737 /* If the THEN/ELSE clause merely assigns a value to a variable/parameter
1738 which is already known to contain that value, then remove the useless
1739 THEN/ELSE clause. */
1740 if (TREE_CODE (stmt) == MODIFY_EXPR
1741 && TREE_OPERAND (stmt, 0) == var
1742 && operand_equal_p (val, TREE_OPERAND (stmt, 1), 0))
1748 /* Invalidate the var if we encounter something that could modify it.
1749 Likewise for the value it was previously set to. Note that we only
1750 consider values that are either a VAR_DECL or PARM_DECL so we
1751 can test for conflict very simply. */
1752 if (TREE_CODE (stmt) == ASM_EXPR
1753 || (TREE_CODE (stmt) == MODIFY_EXPR
1754 && (TREE_OPERAND (stmt, 0) == var
1755 || TREE_OPERAND (stmt, 0) == val)))
1763 /* A CFG-aware version of remove_useless_stmts. */
1766 cfg_remove_useless_stmts (void)
1770 #ifdef ENABLE_CHECKING
1771 verify_flow_info ();
1776 cfg_remove_useless_stmts_bb (bb);
1781 /* Remove PHI nodes associated with basic block BB and all edges out of BB. */
1784 remove_phi_nodes_and_edges_for_unreachable_block (basic_block bb)
1788 /* Since this block is no longer reachable, we can just delete all
1789 of its PHI nodes. */
1790 phi = phi_nodes (bb);
1793 tree next = PHI_CHAIN (phi);
1794 remove_phi_node (phi, NULL_TREE, bb);
1798 /* Remove edges to BB's successors. */
1799 while (EDGE_COUNT (bb->succs) > 0)
1800 ssa_remove_edge (EDGE_SUCC (bb, 0));
1804 /* Remove statements of basic block BB. */
1807 remove_bb (basic_block bb)
1809 block_stmt_iterator i;
1810 source_locus loc = 0;
1814 fprintf (dump_file, "Removing basic block %d\n", bb->index);
1815 if (dump_flags & TDF_DETAILS)
1817 dump_bb (bb, dump_file, 0);
1818 fprintf (dump_file, "\n");
1822 /* Remove all the instructions in the block. */
1823 for (i = bsi_start (bb); !bsi_end_p (i); bsi_remove (&i))
1825 tree stmt = bsi_stmt (i);
1826 release_defs (stmt);
1828 set_bb_for_stmt (stmt, NULL);
1830 /* Don't warn for removed gotos. Gotos are often removed due to
1831 jump threading, thus resulting in bogus warnings. Not great,
1832 since this way we lose warnings for gotos in the original
1833 program that are indeed unreachable. */
1834 if (TREE_CODE (stmt) != GOTO_EXPR && EXPR_HAS_LOCATION (stmt) && !loc)
1835 #ifdef USE_MAPPED_LOCATION
1836 loc = EXPR_LOCATION (stmt);
1838 loc = EXPR_LOCUS (stmt);
1842 /* If requested, give a warning that the first statement in the
1843 block is unreachable. We walk statements backwards in the
1844 loop above, so the last statement we process is the first statement
1846 if (warn_notreached && loc)
1847 #ifdef USE_MAPPED_LOCATION
1848 warning ("%Hwill never be executed", &loc);
1850 warning ("%Hwill never be executed", loc);
1853 remove_phi_nodes_and_edges_for_unreachable_block (bb);
1857 /* Examine BB to determine if it is a forwarding block (a block which only
1858 transfers control to a new destination). If BB is a forwarding block,
1859 then return the edge leading to the ultimate destination. */
1862 tree_block_forwards_to (basic_block bb)
1864 block_stmt_iterator bsi;
1865 bb_ann_t ann = bb_ann (bb);
1868 /* If this block is not forwardable, then avoid useless work. */
1869 if (! ann->forwardable)
1872 /* Set this block to not be forwardable. This prevents infinite loops since
1873 any block currently under examination is considered non-forwardable. */
1874 ann->forwardable = 0;
1876 /* No forwarding is possible if this block is a special block (ENTRY/EXIT),
1877 this block has more than one successor, this block's single successor is
1878 reached via an abnormal edge, this block has phi nodes, or this block's
1879 single successor has phi nodes. */
1880 if (bb == EXIT_BLOCK_PTR
1881 || bb == ENTRY_BLOCK_PTR
1882 || EDGE_COUNT (bb->succs) != 1
1883 || EDGE_SUCC (bb, 0)->dest == EXIT_BLOCK_PTR
1884 || (EDGE_SUCC (bb, 0)->flags & EDGE_ABNORMAL) != 0
1886 || phi_nodes (EDGE_SUCC (bb, 0)->dest))
1889 /* Walk past any labels at the start of this block. */
1890 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
1892 stmt = bsi_stmt (bsi);
1893 if (TREE_CODE (stmt) != LABEL_EXPR)
1897 /* If we reached the end of this block we may be able to optimize this
1899 if (bsi_end_p (bsi))
1903 /* Recursive call to pick up chains of forwarding blocks. */
1904 dest = tree_block_forwards_to (EDGE_SUCC (bb, 0)->dest);
1906 /* If none found, we forward to bb->succs[0] at minimum. */
1908 dest = EDGE_SUCC (bb, 0);
1910 ann->forwardable = 1;
1914 /* No forwarding possible. */
1919 /* Try to remove superfluous control structures. */
1922 cleanup_control_flow (void)
1925 block_stmt_iterator bsi;
1926 bool retval = false;
1931 bsi = bsi_last (bb);
1933 if (bsi_end_p (bsi))
1936 stmt = bsi_stmt (bsi);
1937 if (TREE_CODE (stmt) == COND_EXPR
1938 || TREE_CODE (stmt) == SWITCH_EXPR)
1939 retval |= cleanup_control_expr_graph (bb, bsi);
1945 /* Disconnect an unreachable block in the control expression starting
1949 cleanup_control_expr_graph (basic_block bb, block_stmt_iterator bsi)
1952 bool retval = false;
1953 tree expr = bsi_stmt (bsi), val;
1955 if (EDGE_COUNT (bb->succs) > 1)
1960 switch (TREE_CODE (expr))
1963 val = COND_EXPR_COND (expr);
1967 val = SWITCH_COND (expr);
1968 if (TREE_CODE (val) != INTEGER_CST)
1976 taken_edge = find_taken_edge (bb, val);
1980 /* Remove all the edges except the one that is always executed. */
1981 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
1983 if (e != taken_edge)
1985 taken_edge->probability += e->probability;
1986 taken_edge->count += e->count;
1987 ssa_remove_edge (e);
1993 if (taken_edge->probability > REG_BR_PROB_BASE)
1994 taken_edge->probability = REG_BR_PROB_BASE;
1997 taken_edge = EDGE_SUCC (bb, 0);
2000 taken_edge->flags = EDGE_FALLTHRU;
2002 /* We removed some paths from the cfg. */
2003 if (dom_computed[CDI_DOMINATORS] >= DOM_CONS_OK)
2004 dom_computed[CDI_DOMINATORS] = DOM_CONS_OK;
2010 /* Given a control block BB and a predicate VAL, return the edge that
2011 will be taken out of the block. If VAL does not match a unique
2012 edge, NULL is returned. */
2015 find_taken_edge (basic_block bb, tree val)
2019 stmt = last_stmt (bb);
2022 gcc_assert (is_ctrl_stmt (stmt));
2024 /* If VAL is a predicate of the form N RELOP N, where N is an
2025 SSA_NAME, we can usually determine its truth value. */
2026 if (val && COMPARISON_CLASS_P (val))
2029 /* If VAL is not a constant, we can't determine which edge might
2031 if (val == NULL || !really_constant_p (val))
2034 if (TREE_CODE (stmt) == COND_EXPR)
2035 return find_taken_edge_cond_expr (bb, val);
2037 if (TREE_CODE (stmt) == SWITCH_EXPR)
2038 return find_taken_edge_switch_expr (bb, val);
2040 return EDGE_SUCC (bb, 0);
2044 /* Given a constant value VAL and the entry block BB to a COND_EXPR
2045 statement, determine which of the two edges will be taken out of the
2046 block. Return NULL if either edge may be taken. */
2049 find_taken_edge_cond_expr (basic_block bb, tree val)
2051 edge true_edge, false_edge;
2053 extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
2055 /* If both edges of the branch lead to the same basic block, it doesn't
2056 matter which edge is taken. */
2057 if (true_edge->dest == false_edge->dest)
2060 /* Otherwise, try to determine which branch of the if() will be taken.
2061 If VAL is a constant but it can't be reduced to a 0 or a 1, then
2062 we don't really know which edge will be taken at runtime. This
2063 may happen when comparing addresses (e.g., if (&var1 == 4)). */
2064 if (integer_nonzerop (val))
2066 else if (integer_zerop (val))
2073 /* Given a constant value VAL and the entry block BB to a SWITCH_EXPR
2074 statement, determine which edge will be taken out of the block. Return
2075 NULL if any edge may be taken. */
2078 find_taken_edge_switch_expr (basic_block bb, tree val)
2080 tree switch_expr, taken_case;
2081 basic_block dest_bb;
2084 if (TREE_CODE (val) != INTEGER_CST)
2087 switch_expr = last_stmt (bb);
2088 taken_case = find_case_label_for_value (switch_expr, val);
2089 dest_bb = label_to_block (CASE_LABEL (taken_case));
2091 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 gcc_assert (n1 >= 0);
2156 gcc_assert (n2 >= 0);
2158 val1 = PHI_ARG_DEF (phi, n1);
2159 val2 = PHI_ARG_DEF (phi, n2);
2161 if (!operand_equal_p (val1, val2, 0))
2169 /*---------------------------------------------------------------------------
2171 ---------------------------------------------------------------------------*/
2173 /* Dump tree-specific information of block BB to file OUTF. */
2176 tree_dump_bb (basic_block bb, FILE *outf, int indent)
2178 dump_generic_bb (outf, bb, indent, TDF_VOPS);
2182 /* Dump a basic block on stderr. */
2185 debug_tree_bb (basic_block bb)
2187 dump_bb (bb, stderr, 0);
2191 /* Dump basic block with index N on stderr. */
2194 debug_tree_bb_n (int n)
2196 debug_tree_bb (BASIC_BLOCK (n));
2197 return BASIC_BLOCK (n);
2201 /* Dump the CFG on stderr.
2203 FLAGS are the same used by the tree dumping functions
2204 (see TDF_* in tree.h). */
2207 debug_tree_cfg (int flags)
2209 dump_tree_cfg (stderr, flags);
2213 /* Dump the program showing basic block boundaries on the given FILE.
2215 FLAGS are the same used by the tree dumping functions (see TDF_* in
2219 dump_tree_cfg (FILE *file, int flags)
2221 if (flags & TDF_DETAILS)
2223 const char *funcname
2224 = lang_hooks.decl_printable_name (current_function_decl, 2);
2227 fprintf (file, ";; Function %s\n\n", funcname);
2228 fprintf (file, ";; \n%d basic blocks, %d edges, last basic block %d.\n\n",
2229 n_basic_blocks, n_edges, last_basic_block);
2231 brief_dump_cfg (file);
2232 fprintf (file, "\n");
2235 if (flags & TDF_STATS)
2236 dump_cfg_stats (file);
2238 dump_function_to_file (current_function_decl, file, flags | TDF_BLOCKS);
2242 /* Dump CFG statistics on FILE. */
2245 dump_cfg_stats (FILE *file)
2247 static long max_num_merged_labels = 0;
2248 unsigned long size, total = 0;
2251 const char * const fmt_str = "%-30s%-13s%12s\n";
2252 const char * const fmt_str_1 = "%-30s%13d%11lu%c\n";
2253 const char * const fmt_str_3 = "%-43s%11lu%c\n";
2254 const char *funcname
2255 = lang_hooks.decl_printable_name (current_function_decl, 2);
2258 fprintf (file, "\nCFG Statistics for %s\n\n", funcname);
2260 fprintf (file, "---------------------------------------------------------\n");
2261 fprintf (file, fmt_str, "", " Number of ", "Memory");
2262 fprintf (file, fmt_str, "", " instances ", "used ");
2263 fprintf (file, "---------------------------------------------------------\n");
2265 size = n_basic_blocks * sizeof (struct basic_block_def);
2267 fprintf (file, fmt_str_1, "Basic blocks", n_basic_blocks,
2268 SCALE (size), LABEL (size));
2272 n_edges += EDGE_COUNT (bb->succs);
2273 size = n_edges * sizeof (struct edge_def);
2275 fprintf (file, fmt_str_1, "Edges", n_edges, SCALE (size), LABEL (size));
2277 size = n_basic_blocks * sizeof (struct bb_ann_d);
2279 fprintf (file, fmt_str_1, "Basic block annotations", n_basic_blocks,
2280 SCALE (size), LABEL (size));
2282 fprintf (file, "---------------------------------------------------------\n");
2283 fprintf (file, fmt_str_3, "Total memory used by CFG data", SCALE (total),
2285 fprintf (file, "---------------------------------------------------------\n");
2286 fprintf (file, "\n");
2288 if (cfg_stats.num_merged_labels > max_num_merged_labels)
2289 max_num_merged_labels = cfg_stats.num_merged_labels;
2291 fprintf (file, "Coalesced label blocks: %ld (Max so far: %ld)\n",
2292 cfg_stats.num_merged_labels, max_num_merged_labels);
2294 fprintf (file, "\n");
2298 /* Dump CFG statistics on stderr. Keep extern so that it's always
2299 linked in the final executable. */
2302 debug_cfg_stats (void)
2304 dump_cfg_stats (stderr);
2308 /* Dump the flowgraph to a .vcg FILE. */
2311 tree_cfg2vcg (FILE *file)
2316 const char *funcname
2317 = lang_hooks.decl_printable_name (current_function_decl, 2);
2319 /* Write the file header. */
2320 fprintf (file, "graph: { title: \"%s\"\n", funcname);
2321 fprintf (file, "node: { title: \"ENTRY\" label: \"ENTRY\" }\n");
2322 fprintf (file, "node: { title: \"EXIT\" label: \"EXIT\" }\n");
2324 /* Write blocks and edges. */
2325 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
2327 fprintf (file, "edge: { sourcename: \"ENTRY\" targetname: \"%d\"",
2330 if (e->flags & EDGE_FAKE)
2331 fprintf (file, " linestyle: dotted priority: 10");
2333 fprintf (file, " linestyle: solid priority: 100");
2335 fprintf (file, " }\n");
2341 enum tree_code head_code, end_code;
2342 const char *head_name, *end_name;
2345 tree first = first_stmt (bb);
2346 tree last = last_stmt (bb);
2350 head_code = TREE_CODE (first);
2351 head_name = tree_code_name[head_code];
2352 head_line = get_lineno (first);
2355 head_name = "no-statement";
2359 end_code = TREE_CODE (last);
2360 end_name = tree_code_name[end_code];
2361 end_line = get_lineno (last);
2364 end_name = "no-statement";
2366 fprintf (file, "node: { title: \"%d\" label: \"#%d\\n%s (%d)\\n%s (%d)\"}\n",
2367 bb->index, bb->index, head_name, head_line, end_name,
2370 FOR_EACH_EDGE (e, ei, bb->succs)
2372 if (e->dest == EXIT_BLOCK_PTR)
2373 fprintf (file, "edge: { sourcename: \"%d\" targetname: \"EXIT\"", bb->index);
2375 fprintf (file, "edge: { sourcename: \"%d\" targetname: \"%d\"", bb->index, e->dest->index);
2377 if (e->flags & EDGE_FAKE)
2378 fprintf (file, " priority: 10 linestyle: dotted");
2380 fprintf (file, " priority: 100 linestyle: solid");
2382 fprintf (file, " }\n");
2385 if (bb->next_bb != EXIT_BLOCK_PTR)
2389 fputs ("}\n\n", file);
2394 /*---------------------------------------------------------------------------
2395 Miscellaneous helpers
2396 ---------------------------------------------------------------------------*/
2398 /* Return true if T represents a stmt that always transfers control. */
2401 is_ctrl_stmt (tree t)
2403 return (TREE_CODE (t) == COND_EXPR
2404 || TREE_CODE (t) == SWITCH_EXPR
2405 || TREE_CODE (t) == GOTO_EXPR
2406 || TREE_CODE (t) == RETURN_EXPR
2407 || TREE_CODE (t) == RESX_EXPR);
2411 /* Return true if T is a statement that may alter the flow of control
2412 (e.g., a call to a non-returning function). */
2415 is_ctrl_altering_stmt (tree t)
2420 call = get_call_expr_in (t);
2423 /* A non-pure/const CALL_EXPR alters flow control if the current
2424 function has nonlocal labels. */
2425 if (TREE_SIDE_EFFECTS (call) && current_function_has_nonlocal_label)
2428 /* A CALL_EXPR also alters control flow if it does not return. */
2429 if (call_expr_flags (call) & (ECF_NORETURN | ECF_LONGJMP))
2433 /* If a statement can throw, it alters control flow. */
2434 return tree_can_throw_internal (t);
2438 /* Return true if T is a computed goto. */
2441 computed_goto_p (tree t)
2443 return (TREE_CODE (t) == GOTO_EXPR
2444 && TREE_CODE (GOTO_DESTINATION (t)) != LABEL_DECL);
2448 /* Checks whether EXPR is a simple local goto. */
2451 simple_goto_p (tree expr)
2453 return (TREE_CODE (expr) == GOTO_EXPR
2454 && TREE_CODE (GOTO_DESTINATION (expr)) == LABEL_DECL);
2458 /* Return true if T should start a new basic block. PREV_T is the
2459 statement preceding T. It is used when T is a label or a case label.
2460 Labels should only start a new basic block if their previous statement
2461 wasn't a label. Otherwise, sequence of labels would generate
2462 unnecessary basic blocks that only contain a single label. */
2465 stmt_starts_bb_p (tree t, tree prev_t)
2467 enum tree_code code;
2472 /* LABEL_EXPRs start a new basic block only if the preceding
2473 statement wasn't a label of the same type. This prevents the
2474 creation of consecutive blocks that have nothing but a single
2476 code = TREE_CODE (t);
2477 if (code == LABEL_EXPR)
2479 /* Nonlocal and computed GOTO targets always start a new block. */
2480 if (code == LABEL_EXPR
2481 && (DECL_NONLOCAL (LABEL_EXPR_LABEL (t))
2482 || FORCED_LABEL (LABEL_EXPR_LABEL (t))))
2485 if (prev_t && TREE_CODE (prev_t) == code)
2487 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (prev_t)))
2490 cfg_stats.num_merged_labels++;
2501 /* Return true if T should end a basic block. */
2504 stmt_ends_bb_p (tree t)
2506 return is_ctrl_stmt (t) || is_ctrl_altering_stmt (t);
2510 /* Add gotos that used to be represented implicitly in the CFG. */
2513 disband_implicit_edges (void)
2516 block_stmt_iterator last;
2523 last = bsi_last (bb);
2524 stmt = last_stmt (bb);
2526 if (stmt && TREE_CODE (stmt) == COND_EXPR)
2528 /* Remove superfluous gotos from COND_EXPR branches. Moved
2529 from cfg_remove_useless_stmts here since it violates the
2530 invariants for tree--cfg correspondence and thus fits better
2531 here where we do it anyway. */
2532 FOR_EACH_EDGE (e, ei, bb->succs)
2534 if (e->dest != bb->next_bb)
2537 if (e->flags & EDGE_TRUE_VALUE)
2538 COND_EXPR_THEN (stmt) = build_empty_stmt ();
2539 else if (e->flags & EDGE_FALSE_VALUE)
2540 COND_EXPR_ELSE (stmt) = build_empty_stmt ();
2543 e->flags |= EDGE_FALLTHRU;
2549 if (stmt && TREE_CODE (stmt) == RETURN_EXPR)
2551 /* Remove the RETURN_EXPR if we may fall though to the exit
2553 gcc_assert (EDGE_COUNT (bb->succs) == 1);
2554 gcc_assert (EDGE_SUCC (bb, 0)->dest == EXIT_BLOCK_PTR);
2556 if (bb->next_bb == EXIT_BLOCK_PTR
2557 && !TREE_OPERAND (stmt, 0))
2560 EDGE_SUCC (bb, 0)->flags |= EDGE_FALLTHRU;
2565 /* There can be no fallthru edge if the last statement is a control
2567 if (stmt && is_ctrl_stmt (stmt))
2570 /* Find a fallthru edge and emit the goto if necessary. */
2571 FOR_EACH_EDGE (e, ei, bb->succs)
2572 if (e->flags & EDGE_FALLTHRU)
2575 if (!e || e->dest == bb->next_bb)
2578 gcc_assert (e->dest != EXIT_BLOCK_PTR);
2579 label = tree_block_label (e->dest);
2581 stmt = build1 (GOTO_EXPR, void_type_node, label);
2582 #ifdef USE_MAPPED_LOCATION
2583 SET_EXPR_LOCATION (stmt, e->goto_locus);
2585 SET_EXPR_LOCUS (stmt, e->goto_locus);
2587 bsi_insert_after (&last, stmt, BSI_NEW_STMT);
2588 e->flags &= ~EDGE_FALLTHRU;
2592 /* Remove block annotations and other datastructures. */
2595 delete_tree_cfg_annotations (void)
2598 if (n_basic_blocks > 0)
2599 free_blocks_annotations ();
2601 label_to_block_map = NULL;
2608 /* Return the first statement in basic block BB. */
2611 first_stmt (basic_block bb)
2613 block_stmt_iterator i = bsi_start (bb);
2614 return !bsi_end_p (i) ? bsi_stmt (i) : NULL_TREE;
2618 /* Return the last statement in basic block BB. */
2621 last_stmt (basic_block bb)
2623 block_stmt_iterator b = bsi_last (bb);
2624 return !bsi_end_p (b) ? bsi_stmt (b) : NULL_TREE;
2628 /* Return a pointer to the last statement in block BB. */
2631 last_stmt_ptr (basic_block bb)
2633 block_stmt_iterator last = bsi_last (bb);
2634 return !bsi_end_p (last) ? bsi_stmt_ptr (last) : NULL;
2638 /* Return the last statement of an otherwise empty block. Return NULL
2639 if the block is totally empty, or if it contains more than one
2643 last_and_only_stmt (basic_block bb)
2645 block_stmt_iterator i = bsi_last (bb);
2651 last = bsi_stmt (i);
2656 /* Empty statements should no longer appear in the instruction stream.
2657 Everything that might have appeared before should be deleted by
2658 remove_useless_stmts, and the optimizers should just bsi_remove
2659 instead of smashing with build_empty_stmt.
2661 Thus the only thing that should appear here in a block containing
2662 one executable statement is a label. */
2663 prev = bsi_stmt (i);
2664 if (TREE_CODE (prev) == LABEL_EXPR)
2671 /* Mark BB as the basic block holding statement T. */
2674 set_bb_for_stmt (tree t, basic_block bb)
2676 if (TREE_CODE (t) == PHI_NODE)
2678 else if (TREE_CODE (t) == STATEMENT_LIST)
2680 tree_stmt_iterator i;
2681 for (i = tsi_start (t); !tsi_end_p (i); tsi_next (&i))
2682 set_bb_for_stmt (tsi_stmt (i), bb);
2686 stmt_ann_t ann = get_stmt_ann (t);
2689 /* If the statement is a label, add the label to block-to-labels map
2690 so that we can speed up edge creation for GOTO_EXPRs. */
2691 if (TREE_CODE (t) == LABEL_EXPR)
2695 t = LABEL_EXPR_LABEL (t);
2696 uid = LABEL_DECL_UID (t);
2699 LABEL_DECL_UID (t) = uid = cfun->last_label_uid++;
2700 if (VARRAY_SIZE (label_to_block_map) <= (unsigned) uid)
2701 VARRAY_GROW (label_to_block_map, 3 * uid / 2);
2704 /* We're moving an existing label. Make sure that we've
2705 removed it from the old block. */
2706 gcc_assert (!bb || !VARRAY_BB (label_to_block_map, uid));
2707 VARRAY_BB (label_to_block_map, uid) = bb;
2712 /* Finds iterator for STMT. */
2714 extern block_stmt_iterator
2715 stmt_for_bsi (tree stmt)
2717 block_stmt_iterator bsi;
2719 for (bsi = bsi_start (bb_for_stmt (stmt)); !bsi_end_p (bsi); bsi_next (&bsi))
2720 if (bsi_stmt (bsi) == stmt)
2726 /* Insert statement (or statement list) T before the statement
2727 pointed-to by iterator I. M specifies how to update iterator I
2728 after insertion (see enum bsi_iterator_update). */
2731 bsi_insert_before (block_stmt_iterator *i, tree t, enum bsi_iterator_update m)
2733 set_bb_for_stmt (t, i->bb);
2734 tsi_link_before (&i->tsi, t, m);
2739 /* Insert statement (or statement list) T after the statement
2740 pointed-to by iterator I. M specifies how to update iterator I
2741 after insertion (see enum bsi_iterator_update). */
2744 bsi_insert_after (block_stmt_iterator *i, tree t, enum bsi_iterator_update m)
2746 set_bb_for_stmt (t, i->bb);
2747 tsi_link_after (&i->tsi, t, m);
2752 /* Remove the statement pointed to by iterator I. The iterator is updated
2753 to the next statement. */
2756 bsi_remove (block_stmt_iterator *i)
2758 tree t = bsi_stmt (*i);
2759 set_bb_for_stmt (t, NULL);
2760 tsi_delink (&i->tsi);
2764 /* Move the statement at FROM so it comes right after the statement at TO. */
2767 bsi_move_after (block_stmt_iterator *from, block_stmt_iterator *to)
2769 tree stmt = bsi_stmt (*from);
2771 bsi_insert_after (to, stmt, BSI_SAME_STMT);
2775 /* Move the statement at FROM so it comes right before the statement at TO. */
2778 bsi_move_before (block_stmt_iterator *from, block_stmt_iterator *to)
2780 tree stmt = bsi_stmt (*from);
2782 bsi_insert_before (to, stmt, BSI_SAME_STMT);
2786 /* Move the statement at FROM to the end of basic block BB. */
2789 bsi_move_to_bb_end (block_stmt_iterator *from, basic_block bb)
2791 block_stmt_iterator last = bsi_last (bb);
2793 /* Have to check bsi_end_p because it could be an empty block. */
2794 if (!bsi_end_p (last) && is_ctrl_stmt (bsi_stmt (last)))
2795 bsi_move_before (from, &last);
2797 bsi_move_after (from, &last);
2801 /* Replace the contents of the statement pointed to by iterator BSI
2802 with STMT. If PRESERVE_EH_INFO is true, the exception handling
2803 information of the original statement is preserved. */
2806 bsi_replace (const block_stmt_iterator *bsi, tree stmt, bool preserve_eh_info)
2809 tree orig_stmt = bsi_stmt (*bsi);
2811 SET_EXPR_LOCUS (stmt, EXPR_LOCUS (orig_stmt));
2812 set_bb_for_stmt (stmt, bsi->bb);
2814 /* Preserve EH region information from the original statement, if
2815 requested by the caller. */
2816 if (preserve_eh_info)
2818 eh_region = lookup_stmt_eh_region (orig_stmt);
2820 add_stmt_to_eh_region (stmt, eh_region);
2823 *bsi_stmt_ptr (*bsi) = stmt;
2828 /* Insert the statement pointed-to by BSI into edge E. Every attempt
2829 is made to place the statement in an existing basic block, but
2830 sometimes that isn't possible. When it isn't possible, the edge is
2831 split and the statement is added to the new block.
2833 In all cases, the returned *BSI points to the correct location. The
2834 return value is true if insertion should be done after the location,
2835 or false if it should be done before the location. If new basic block
2836 has to be created, it is stored in *NEW_BB. */
2839 tree_find_edge_insert_loc (edge e, block_stmt_iterator *bsi,
2840 basic_block *new_bb)
2842 basic_block dest, src;
2848 /* If the destination has one predecessor which has no PHI nodes,
2849 insert there. Except for the exit block.
2851 The requirement for no PHI nodes could be relaxed. Basically we
2852 would have to examine the PHIs to prove that none of them used
2853 the value set by the statement we want to insert on E. That
2854 hardly seems worth the effort. */
2855 if (EDGE_COUNT (dest->preds) == 1
2856 && ! phi_nodes (dest)
2857 && dest != EXIT_BLOCK_PTR)
2859 *bsi = bsi_start (dest);
2860 if (bsi_end_p (*bsi))
2863 /* Make sure we insert after any leading labels. */
2864 tmp = bsi_stmt (*bsi);
2865 while (TREE_CODE (tmp) == LABEL_EXPR)
2868 if (bsi_end_p (*bsi))
2870 tmp = bsi_stmt (*bsi);
2873 if (bsi_end_p (*bsi))
2875 *bsi = bsi_last (dest);
2882 /* If the source has one successor, the edge is not abnormal and
2883 the last statement does not end a basic block, insert there.
2884 Except for the entry block. */
2886 if ((e->flags & EDGE_ABNORMAL) == 0
2887 && EDGE_COUNT (src->succs) == 1
2888 && src != ENTRY_BLOCK_PTR)
2890 *bsi = bsi_last (src);
2891 if (bsi_end_p (*bsi))
2894 tmp = bsi_stmt (*bsi);
2895 if (!stmt_ends_bb_p (tmp))
2898 /* Insert code just before returning the value. We may need to decompose
2899 the return in the case it contains non-trivial operand. */
2900 if (TREE_CODE (tmp) == RETURN_EXPR)
2902 tree op = TREE_OPERAND (tmp, 0);
2903 if (!is_gimple_val (op))
2905 gcc_assert (TREE_CODE (op) == MODIFY_EXPR);
2906 bsi_insert_before (bsi, op, BSI_NEW_STMT);
2907 TREE_OPERAND (tmp, 0) = TREE_OPERAND (op, 0);
2914 /* Otherwise, create a new basic block, and split this edge. */
2915 dest = split_edge (e);
2918 e = EDGE_PRED (dest, 0);
2923 /* This routine will commit all pending edge insertions, creating any new
2924 basic blocks which are necessary.
2926 If specified, NEW_BLOCKS returns a count of the number of new basic
2927 blocks which were created. */
2930 bsi_commit_edge_inserts (int *new_blocks)
2937 blocks = n_basic_blocks;
2939 bsi_commit_edge_inserts_1 (EDGE_SUCC (ENTRY_BLOCK_PTR, 0));
2942 FOR_EACH_EDGE (e, ei, bb->succs)
2943 bsi_commit_edge_inserts_1 (e);
2946 *new_blocks = n_basic_blocks - blocks;
2950 /* Commit insertions pending at edge E. */
2953 bsi_commit_edge_inserts_1 (edge e)
2955 if (PENDING_STMT (e))
2957 block_stmt_iterator bsi;
2958 tree stmt = PENDING_STMT (e);
2960 PENDING_STMT (e) = NULL_TREE;
2962 if (tree_find_edge_insert_loc (e, &bsi, NULL))
2963 bsi_insert_after (&bsi, stmt, BSI_NEW_STMT);
2965 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
2970 /* Add STMT to the pending list of edge E. No actual insertion is
2971 made until a call to bsi_commit_edge_inserts () is made. */
2974 bsi_insert_on_edge (edge e, tree stmt)
2976 append_to_statement_list (stmt, &PENDING_STMT (e));
2979 /* Similar to bsi_insert_on_edge+bsi_commit_edge_inserts. If new block has to
2980 be created, it is returned. */
2983 bsi_insert_on_edge_immediate (edge e, tree stmt)
2985 block_stmt_iterator bsi;
2986 basic_block new_bb = NULL;
2988 gcc_assert (!PENDING_STMT (e));
2990 if (tree_find_edge_insert_loc (e, &bsi, &new_bb))
2991 bsi_insert_after (&bsi, stmt, BSI_NEW_STMT);
2993 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
2998 /*---------------------------------------------------------------------------
2999 Tree specific functions for CFG manipulation
3000 ---------------------------------------------------------------------------*/
3002 /* Split a (typically critical) edge EDGE_IN. Return the new block.
3003 Abort on abnormal edges. */
3006 tree_split_edge (edge edge_in)
3008 basic_block new_bb, after_bb, dest, src;
3014 /* Abnormal edges cannot be split. */
3015 gcc_assert (!(edge_in->flags & EDGE_ABNORMAL));
3018 dest = edge_in->dest;
3020 /* Place the new block in the block list. Try to keep the new block
3021 near its "logical" location. This is of most help to humans looking
3022 at debugging dumps. */
3023 FOR_EACH_EDGE (e, ei, dest->preds)
3024 if (e->src->next_bb == dest)
3027 after_bb = dest->prev_bb;
3029 after_bb = edge_in->src;
3031 new_bb = create_empty_bb (after_bb);
3032 new_bb->frequency = EDGE_FREQUENCY (edge_in);
3033 new_bb->count = edge_in->count;
3034 new_edge = make_edge (new_bb, dest, EDGE_FALLTHRU);
3035 new_edge->probability = REG_BR_PROB_BASE;
3036 new_edge->count = edge_in->count;
3038 /* Find all the PHI arguments on the original edge, and change them to
3039 the new edge. Do it before redirection, so that the argument does not
3041 for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi))
3043 num_elem = PHI_NUM_ARGS (phi);
3044 for (i = 0; i < num_elem; i++)
3045 if (PHI_ARG_EDGE (phi, i) == edge_in)
3047 PHI_ARG_EDGE (phi, i) = new_edge;
3052 e = redirect_edge_and_branch (edge_in, new_bb);
3054 gcc_assert (!PENDING_STMT (edge_in));
3060 /* Return true when BB has label LABEL in it. */
3063 has_label_p (basic_block bb, tree label)
3065 block_stmt_iterator bsi;
3067 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3069 tree stmt = bsi_stmt (bsi);
3071 if (TREE_CODE (stmt) != LABEL_EXPR)
3073 if (LABEL_EXPR_LABEL (stmt) == label)
3080 /* Callback for walk_tree, check that all elements with address taken are
3081 properly noticed as such. */
3084 verify_expr (tree *tp, int *walk_subtrees, void *data ATTRIBUTE_UNUSED)
3091 /* Check operand N for being valid GIMPLE and give error MSG if not.
3092 We check for constants explicitly since they are not considered
3093 gimple invariants if they overflowed. */
3094 #define CHECK_OP(N, MSG) \
3095 do { if (!CONSTANT_CLASS_P (TREE_OPERAND (t, N)) \
3096 && !is_gimple_val (TREE_OPERAND (t, N))) \
3097 { error (MSG); return TREE_OPERAND (t, N); }} while (0)
3099 switch (TREE_CODE (t))
3102 if (SSA_NAME_IN_FREE_LIST (t))
3104 error ("SSA name in freelist but still referenced");
3110 x = TREE_OPERAND (t, 0);
3111 if (TREE_CODE (x) == BIT_FIELD_REF
3112 && is_gimple_reg (TREE_OPERAND (x, 0)))
3114 error ("GIMPLE register modified with BIT_FIELD_REF");
3120 /* Skip any references (they will be checked when we recurse down the
3121 tree) and ensure that any variable used as a prefix is marked
3123 for (x = TREE_OPERAND (t, 0);
3124 (handled_component_p (x)
3125 || TREE_CODE (x) == REALPART_EXPR
3126 || TREE_CODE (x) == IMAGPART_EXPR);
3127 x = TREE_OPERAND (x, 0))
3130 if (TREE_CODE (x) != VAR_DECL && TREE_CODE (x) != PARM_DECL)
3132 if (!TREE_ADDRESSABLE (x))
3134 error ("address taken, but ADDRESSABLE bit not set");
3140 x = TREE_OPERAND (t, 0);
3141 if (TREE_CODE (TREE_TYPE (x)) != BOOLEAN_TYPE)
3143 error ("non-boolean used in condition");
3150 case FIX_TRUNC_EXPR:
3152 case FIX_FLOOR_EXPR:
3153 case FIX_ROUND_EXPR:
3158 case NON_LVALUE_EXPR:
3159 case TRUTH_NOT_EXPR:
3160 CHECK_OP (0, "Invalid operand to unary operator");
3167 case ARRAY_RANGE_REF:
3169 case VIEW_CONVERT_EXPR:
3170 /* We have a nest of references. Verify that each of the operands
3171 that determine where to reference is either a constant or a variable,
3172 verify that the base is valid, and then show we've already checked
3174 while (TREE_CODE (t) == REALPART_EXPR || TREE_CODE (t) == IMAGPART_EXPR
3175 || handled_component_p (t))
3177 if (TREE_CODE (t) == COMPONENT_REF && TREE_OPERAND (t, 2))
3178 CHECK_OP (2, "Invalid COMPONENT_REF offset operator");
3179 else if (TREE_CODE (t) == ARRAY_REF
3180 || TREE_CODE (t) == ARRAY_RANGE_REF)
3182 CHECK_OP (1, "Invalid array index.");
3183 if (TREE_OPERAND (t, 2))
3184 CHECK_OP (2, "Invalid array lower bound.");
3185 if (TREE_OPERAND (t, 3))
3186 CHECK_OP (3, "Invalid array stride.");
3188 else if (TREE_CODE (t) == BIT_FIELD_REF)
3190 CHECK_OP (1, "Invalid operand to BIT_FIELD_REF");
3191 CHECK_OP (2, "Invalid operand to BIT_FIELD_REF");
3194 t = TREE_OPERAND (t, 0);
3197 if (!CONSTANT_CLASS_P (t) && !is_gimple_lvalue (t))
3199 error ("Invalid reference prefix.");
3211 case UNORDERED_EXPR:
3222 case TRUNC_DIV_EXPR:
3224 case FLOOR_DIV_EXPR:
3225 case ROUND_DIV_EXPR:
3226 case TRUNC_MOD_EXPR:
3228 case FLOOR_MOD_EXPR:
3229 case ROUND_MOD_EXPR:
3231 case EXACT_DIV_EXPR:
3241 CHECK_OP (0, "Invalid operand to binary operator");
3242 CHECK_OP (1, "Invalid operand to binary operator");
3254 /* Verify STMT, return true if STMT is not in GIMPLE form.
3255 TODO: Implement type checking. */
3258 verify_stmt (tree stmt, bool last_in_block)
3262 if (!is_gimple_stmt (stmt))
3264 error ("Is not a valid GIMPLE statement.");
3268 addr = walk_tree (&stmt, verify_expr, NULL, NULL);
3271 debug_generic_stmt (addr);
3275 /* If the statement is marked as part of an EH region, then it is
3276 expected that the statement could throw. Verify that when we
3277 have optimizations that simplify statements such that we prove
3278 that they cannot throw, that we update other data structures
3280 if (lookup_stmt_eh_region (stmt) >= 0)
3282 if (!tree_could_throw_p (stmt))
3284 error ("Statement marked for throw, but doesn%'t.");
3287 if (!last_in_block && tree_can_throw_internal (stmt))
3289 error ("Statement marked for throw in middle of block.");
3297 debug_generic_stmt (stmt);
3302 /* Return true when the T can be shared. */
3305 tree_node_can_be_shared (tree t)
3307 if (IS_TYPE_OR_DECL_P (t)
3308 /* We check for constants explicitly since they are not considered
3309 gimple invariants if they overflowed. */
3310 || CONSTANT_CLASS_P (t)
3311 || is_gimple_min_invariant (t)
3312 || TREE_CODE (t) == SSA_NAME)
3315 while (((TREE_CODE (t) == ARRAY_REF || TREE_CODE (t) == ARRAY_RANGE_REF)
3316 /* We check for constants explicitly since they are not considered
3317 gimple invariants if they overflowed. */
3318 && (CONSTANT_CLASS_P (TREE_OPERAND (t, 1))
3319 || is_gimple_min_invariant (TREE_OPERAND (t, 1))))
3320 || (TREE_CODE (t) == COMPONENT_REF
3321 || TREE_CODE (t) == REALPART_EXPR
3322 || TREE_CODE (t) == IMAGPART_EXPR))
3323 t = TREE_OPERAND (t, 0);
3332 /* Called via walk_trees. Verify tree sharing. */
3335 verify_node_sharing (tree * tp, int *walk_subtrees, void *data)
3337 htab_t htab = (htab_t) data;
3340 if (tree_node_can_be_shared (*tp))
3342 *walk_subtrees = false;
3346 slot = htab_find_slot (htab, *tp, INSERT);
3355 /* Verify the GIMPLE statement chain. */
3361 block_stmt_iterator bsi;
3366 timevar_push (TV_TREE_STMT_VERIFY);
3367 htab = htab_create (37, htab_hash_pointer, htab_eq_pointer, NULL);
3374 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
3376 int phi_num_args = PHI_NUM_ARGS (phi);
3378 for (i = 0; i < phi_num_args; i++)
3380 tree t = PHI_ARG_DEF (phi, i);
3383 /* Addressable variables do have SSA_NAMEs but they
3384 are not considered gimple values. */
3385 if (TREE_CODE (t) != SSA_NAME
3386 && TREE_CODE (t) != FUNCTION_DECL
3387 && !is_gimple_val (t))
3389 error ("PHI def is not a GIMPLE value");
3390 debug_generic_stmt (phi);
3391 debug_generic_stmt (t);
3395 addr = walk_tree (&t, verify_expr, NULL, NULL);
3398 debug_generic_stmt (addr);
3402 addr = walk_tree (&t, verify_node_sharing, htab, NULL);
3405 error ("Incorrect sharing of tree nodes");
3406 debug_generic_stmt (phi);
3407 debug_generic_stmt (addr);
3413 for (bsi = bsi_start (bb); !bsi_end_p (bsi); )
3415 tree stmt = bsi_stmt (bsi);
3417 err |= verify_stmt (stmt, bsi_end_p (bsi));
3418 addr = walk_tree (&stmt, verify_node_sharing, htab, NULL);
3421 error ("Incorrect sharing of tree nodes");
3422 debug_generic_stmt (stmt);
3423 debug_generic_stmt (addr);
3430 internal_error ("verify_stmts failed.");
3433 timevar_pop (TV_TREE_STMT_VERIFY);
3437 /* Verifies that the flow information is OK. */
3440 tree_verify_flow_info (void)
3444 block_stmt_iterator bsi;
3449 if (ENTRY_BLOCK_PTR->stmt_list)
3451 error ("ENTRY_BLOCK has a statement list associated with it\n");
3455 if (EXIT_BLOCK_PTR->stmt_list)
3457 error ("EXIT_BLOCK has a statement list associated with it\n");
3461 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
3462 if (e->flags & EDGE_FALLTHRU)
3464 error ("Fallthru to exit from bb %d\n", e->src->index);
3470 bool found_ctrl_stmt = false;
3472 /* Skip labels on the start of basic block. */
3473 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3475 if (TREE_CODE (bsi_stmt (bsi)) != LABEL_EXPR)
3478 if (label_to_block (LABEL_EXPR_LABEL (bsi_stmt (bsi))) != bb)
3480 error ("Label %s to block does not match in bb %d\n",
3481 IDENTIFIER_POINTER (DECL_NAME (bsi_stmt (bsi))),
3486 if (decl_function_context (LABEL_EXPR_LABEL (bsi_stmt (bsi)))
3487 != current_function_decl)
3489 error ("Label %s has incorrect context in bb %d\n",
3490 IDENTIFIER_POINTER (DECL_NAME (bsi_stmt (bsi))),
3496 /* Verify that body of basic block BB is free of control flow. */
3497 for (; !bsi_end_p (bsi); bsi_next (&bsi))
3499 tree stmt = bsi_stmt (bsi);
3501 if (found_ctrl_stmt)
3503 error ("Control flow in the middle of basic block %d\n",
3508 if (stmt_ends_bb_p (stmt))
3509 found_ctrl_stmt = true;
3511 if (TREE_CODE (stmt) == LABEL_EXPR)
3513 error ("Label %s in the middle of basic block %d\n",
3514 IDENTIFIER_POINTER (DECL_NAME (stmt)),
3519 bsi = bsi_last (bb);
3520 if (bsi_end_p (bsi))
3523 stmt = bsi_stmt (bsi);
3525 if (is_ctrl_stmt (stmt))
3527 FOR_EACH_EDGE (e, ei, bb->succs)
3528 if (e->flags & EDGE_FALLTHRU)
3530 error ("Fallthru edge after a control statement in bb %d \n",
3536 switch (TREE_CODE (stmt))
3542 if (TREE_CODE (COND_EXPR_THEN (stmt)) != GOTO_EXPR
3543 || TREE_CODE (COND_EXPR_ELSE (stmt)) != GOTO_EXPR)
3545 error ("Structured COND_EXPR at the end of bb %d\n", bb->index);
3549 extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
3551 if (!true_edge || !false_edge
3552 || !(true_edge->flags & EDGE_TRUE_VALUE)
3553 || !(false_edge->flags & EDGE_FALSE_VALUE)
3554 || (true_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL))
3555 || (false_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL))
3556 || EDGE_COUNT (bb->succs) >= 3)
3558 error ("Wrong outgoing edge flags at end of bb %d\n",
3563 if (!has_label_p (true_edge->dest,
3564 GOTO_DESTINATION (COND_EXPR_THEN (stmt))))
3566 error ("%<then%> label does not match edge at end of bb %d\n",
3571 if (!has_label_p (false_edge->dest,
3572 GOTO_DESTINATION (COND_EXPR_ELSE (stmt))))
3574 error ("%<else%> label does not match edge at end of bb %d\n",
3582 if (simple_goto_p (stmt))
3584 error ("Explicit goto at end of bb %d\n", bb->index);
3589 /* FIXME. We should double check that the labels in the
3590 destination blocks have their address taken. */
3591 FOR_EACH_EDGE (e, ei, bb->succs)
3592 if ((e->flags & (EDGE_FALLTHRU | EDGE_TRUE_VALUE
3593 | EDGE_FALSE_VALUE))
3594 || !(e->flags & EDGE_ABNORMAL))
3596 error ("Wrong outgoing edge flags at end of bb %d\n",
3604 if (EDGE_COUNT (bb->succs) != 1
3605 || (EDGE_SUCC (bb, 0)->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL
3606 | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
3608 error ("Wrong outgoing edge flags at end of bb %d\n", bb->index);
3611 if (EDGE_SUCC (bb, 0)->dest != EXIT_BLOCK_PTR)
3613 error ("Return edge does not point to exit in bb %d\n",
3626 vec = SWITCH_LABELS (stmt);
3627 n = TREE_VEC_LENGTH (vec);
3629 /* Mark all the destination basic blocks. */
3630 for (i = 0; i < n; ++i)
3632 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
3633 basic_block label_bb = label_to_block (lab);
3635 gcc_assert (!label_bb->aux || label_bb->aux == (void *)1);
3636 label_bb->aux = (void *)1;
3639 /* Verify that the case labels are sorted. */
3640 prev = TREE_VEC_ELT (vec, 0);
3641 for (i = 1; i < n - 1; ++i)
3643 tree c = TREE_VEC_ELT (vec, i);
3646 error ("Found default case not at end of case vector");
3650 if (! tree_int_cst_lt (CASE_LOW (prev), CASE_LOW (c)))
3652 error ("Case labels not sorted:\n ");
3653 print_generic_expr (stderr, prev, 0);
3654 fprintf (stderr," is greater than ");
3655 print_generic_expr (stderr, c, 0);
3656 fprintf (stderr," but comes before it.\n");
3661 if (CASE_LOW (TREE_VEC_ELT (vec, n - 1)))
3663 error ("No default case found at end of case vector");
3667 FOR_EACH_EDGE (e, ei, bb->succs)
3671 error ("Extra outgoing edge %d->%d\n",
3672 bb->index, e->dest->index);
3675 e->dest->aux = (void *)2;
3676 if ((e->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL
3677 | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
3679 error ("Wrong outgoing edge flags at end of bb %d\n",
3685 /* Check that we have all of them. */
3686 for (i = 0; i < n; ++i)
3688 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
3689 basic_block label_bb = label_to_block (lab);
3691 if (label_bb->aux != (void *)2)
3693 error ("Missing edge %i->%i\n",
3694 bb->index, label_bb->index);
3699 FOR_EACH_EDGE (e, ei, bb->succs)
3700 e->dest->aux = (void *)0;
3707 if (dom_computed[CDI_DOMINATORS] >= DOM_NO_FAST_QUERY)
3708 verify_dominators (CDI_DOMINATORS);
3714 /* Updates phi nodes after creating forwarder block joined
3715 by edge FALLTHRU. */
3718 tree_make_forwarder_block (edge fallthru)
3722 basic_block dummy, bb;
3723 tree phi, new_phi, var, prev, next;
3725 dummy = fallthru->src;
3726 bb = fallthru->dest;
3728 if (EDGE_COUNT (bb->preds) == 1)
3731 /* If we redirected a branch we must create new phi nodes at the
3733 for (phi = phi_nodes (dummy); phi; phi = PHI_CHAIN (phi))
3735 var = PHI_RESULT (phi);
3736 new_phi = create_phi_node (var, bb);
3737 SSA_NAME_DEF_STMT (var) = new_phi;
3738 SET_PHI_RESULT (phi, make_ssa_name (SSA_NAME_VAR (var), phi));
3739 add_phi_arg (&new_phi, PHI_RESULT (phi), fallthru);
3742 /* Ensure that the PHI node chain is in the same order. */
3744 for (phi = phi_nodes (bb); phi; phi = next)
3746 next = PHI_CHAIN (phi);
3747 PHI_CHAIN (phi) = prev;
3750 set_phi_nodes (bb, prev);
3752 /* Add the arguments we have stored on edges. */
3753 FOR_EACH_EDGE (e, ei, bb->preds)
3758 for (phi = phi_nodes (bb), var = PENDING_STMT (e);
3760 phi = PHI_CHAIN (phi), var = TREE_CHAIN (var))
3761 add_phi_arg (&phi, TREE_VALUE (var), e);
3763 PENDING_STMT (e) = NULL;
3768 /* Return true if basic block BB does nothing except pass control
3769 flow to another block and that we can safely insert a label at
3770 the start of the successor block. */
3773 tree_forwarder_block_p (basic_block bb)
3775 block_stmt_iterator bsi;
3779 /* If we have already determined that this block is not forwardable,
3780 then no further checks are necessary. */
3781 if (! bb_ann (bb)->forwardable)
3784 /* BB must have a single outgoing normal edge. Otherwise it can not be
3785 a forwarder block. */
3786 if (EDGE_COUNT (bb->succs) != 1
3787 || EDGE_SUCC (bb, 0)->dest == EXIT_BLOCK_PTR
3788 || (EDGE_SUCC (bb, 0)->flags & EDGE_ABNORMAL)
3789 || bb == ENTRY_BLOCK_PTR)
3791 bb_ann (bb)->forwardable = 0;
3795 /* Successors of the entry block are not forwarders. */
3796 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
3799 bb_ann (bb)->forwardable = 0;
3803 /* BB can not have any PHI nodes. This could potentially be relaxed
3804 early in compilation if we re-rewrote the variables appearing in
3805 any PHI nodes in forwarder blocks. */
3808 bb_ann (bb)->forwardable = 0;
3812 /* Now walk through the statements. We can ignore labels, anything else
3813 means this is not a forwarder block. */
3814 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3816 tree stmt = bsi_stmt (bsi);
3818 switch (TREE_CODE (stmt))
3821 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)))
3826 bb_ann (bb)->forwardable = 0;
3835 /* Thread jumps over empty statements.
3837 This code should _not_ thread over obviously equivalent conditions
3838 as that requires nontrivial updates to the SSA graph. */
3844 basic_block bb, dest, tmp, old_dest, curr, dom;
3847 bool retval = false;
3850 bb_ann (bb)->forwardable = 1;
3852 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb)
3856 /* Don't waste time on unreachable blocks. */
3857 if (EDGE_COUNT (bb->preds) == 0)
3860 /* Nor on forwarders. */
3861 if (tree_forwarder_block_p (bb))
3864 /* This block is now part of a forwarding path, mark it as not
3865 forwardable so that we can detect loops. This bit will be
3867 bb_ann (bb)->forwardable = 0;
3869 /* Examine each of our block's successors to see if it is
3871 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
3876 /* If the edge is abnormal or its destination is not
3877 forwardable, then there's nothing to do. */
3878 if ((e->flags & EDGE_ABNORMAL)
3879 || !tree_forwarder_block_p (e->dest))
3886 freq = EDGE_FREQUENCY (e);
3888 /* Now walk through as many forwarder blocks as possible to
3889 find the ultimate destination we want to thread our jump
3891 last = EDGE_SUCC (e->dest, 0);
3892 bb_ann (e->dest)->forwardable = 0;
3893 for (dest = EDGE_SUCC (e->dest, 0)->dest;
3894 tree_forwarder_block_p (dest);
3895 last = EDGE_SUCC (dest, 0),
3896 dest = EDGE_SUCC (dest, 0)->dest)
3898 /* An infinite loop detected. We redirect the edge anyway, so
3899 that the loop is shrunk into single basic block. */
3900 if (!bb_ann (dest)->forwardable)
3903 if (EDGE_SUCC (dest, 0)->dest == EXIT_BLOCK_PTR)
3906 bb_ann (dest)->forwardable = 0;
3909 /* Reset the forwardable marks to 1. */
3912 tmp = EDGE_SUCC (tmp, 0)->dest)
3913 bb_ann (tmp)->forwardable = 1;
3915 if (dest == e->dest)
3921 old = find_edge (bb, dest);
3924 /* If there already is an edge, check whether the values
3925 in phi nodes differ. */
3926 if (!phi_alternatives_equal (dest, last, old))
3928 /* The previous block is forwarder. Redirect our jump
3929 to that target instead since we know it has no PHI
3930 nodes that will need updating. */
3933 /* That might mean that no forwarding at all is possible. */
3934 if (dest == e->dest)
3940 old = find_edge (bb, dest);
3944 /* Perform the redirection. */
3947 e = redirect_edge_and_branch (e, dest);
3949 /* Update the profile. */
3950 if (profile_status != PROFILE_ABSENT)
3951 for (curr = old_dest; curr != dest; curr = EDGE_SUCC (curr, 0)->dest)
3953 curr->frequency -= freq;
3954 if (curr->frequency < 0)
3955 curr->frequency = 0;
3956 curr->count -= count;
3957 if (curr->count < 0)
3959 EDGE_SUCC (curr, 0)->count -= count;
3960 if (EDGE_SUCC (curr, 0)->count < 0)
3961 EDGE_SUCC (curr, 0)->count = 0;
3966 /* Update PHI nodes. We know that the new argument should
3967 have the same value as the argument associated with LAST.
3968 Otherwise we would have changed our target block above. */
3969 for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi))
3971 arg = phi_arg_from_edge (phi, last);
3972 gcc_assert (arg >= 0);
3973 add_phi_arg (&phi, PHI_ARG_DEF (phi, arg), e);
3977 /* Update the dominators. */
3978 if (dom_computed[CDI_DOMINATORS] >= DOM_CONS_OK)
3980 /* Remove the unreachable blocks (observe that if all blocks
3981 were reachable before, only those in the path we threaded
3982 over and did not have any predecessor outside of the path
3983 become unreachable). */
3984 for (; old_dest != dest; old_dest = tmp)
3986 tmp = EDGE_SUCC (old_dest, 0)->dest;
3988 if (EDGE_COUNT (old_dest->preds) > 0)
3991 delete_basic_block (old_dest);
3993 /* If the dominator of the destination was in the path, set its
3994 dominator to the start of the redirected edge. */
3995 if (get_immediate_dominator (CDI_DOMINATORS, old_dest) == NULL)
3996 set_immediate_dominator (CDI_DOMINATORS, old_dest, bb);
3998 /* Now proceed like if we forwarded just over one edge at a time.
3999 Algorithm for forwarding edge S --> A over edge A --> B then
4003 && !dominated_by (S, B))
4004 idom (B) = idom (A);
4005 recount_idom (A); */
4007 for (; old_dest != dest; old_dest = tmp)
4009 tmp = EDGE_SUCC (old_dest, 0)->dest;
4011 if (get_immediate_dominator (CDI_DOMINATORS, tmp) == old_dest
4012 && !dominated_by_p (CDI_DOMINATORS, bb, tmp))
4014 dom = get_immediate_dominator (CDI_DOMINATORS, old_dest);
4015 set_immediate_dominator (CDI_DOMINATORS, tmp, dom);
4018 dom = recount_dominator (CDI_DOMINATORS, old_dest);
4019 set_immediate_dominator (CDI_DOMINATORS, old_dest, dom);
4024 /* Reset the forwardable bit on our block since it's no longer in
4025 a forwarding chain path. */
4026 bb_ann (bb)->forwardable = 1;
4033 /* Return a non-special label in the head of basic block BLOCK.
4034 Create one if it doesn't exist. */
4037 tree_block_label (basic_block bb)
4039 block_stmt_iterator i, s = bsi_start (bb);
4043 for (i = s; !bsi_end_p (i); first = false, bsi_next (&i))
4045 stmt = bsi_stmt (i);
4046 if (TREE_CODE (stmt) != LABEL_EXPR)
4048 label = LABEL_EXPR_LABEL (stmt);
4049 if (!DECL_NONLOCAL (label))
4052 bsi_move_before (&i, &s);
4057 label = create_artificial_label ();
4058 stmt = build1 (LABEL_EXPR, void_type_node, label);
4059 bsi_insert_before (&s, stmt, BSI_NEW_STMT);
4064 /* Attempt to perform edge redirection by replacing a possibly complex
4065 jump instruction by a goto or by removing the jump completely.
4066 This can apply only if all edges now point to the same block. The
4067 parameters and return values are equivalent to
4068 redirect_edge_and_branch. */
4071 tree_try_redirect_by_replacing_jump (edge e, basic_block target)
4073 basic_block src = e->src;
4075 block_stmt_iterator b;
4079 /* Verify that all targets will be TARGET. */
4080 FOR_EACH_EDGE (tmp, ei, src->succs)
4081 if (tmp->dest != target && tmp != e)
4090 stmt = bsi_stmt (b);
4092 if (TREE_CODE (stmt) == COND_EXPR
4093 || TREE_CODE (stmt) == SWITCH_EXPR)
4096 e = ssa_redirect_edge (e, target);
4097 e->flags = EDGE_FALLTHRU;
4105 /* Redirect E to DEST. Return NULL on failure. Otherwise, return the
4106 edge representing the redirected branch. */
4109 tree_redirect_edge_and_branch (edge e, basic_block dest)
4111 basic_block bb = e->src;
4112 block_stmt_iterator bsi;
4116 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
4119 if (e->src != ENTRY_BLOCK_PTR
4120 && (ret = tree_try_redirect_by_replacing_jump (e, dest)))
4123 if (e->dest == dest)
4126 label = tree_block_label (dest);
4128 bsi = bsi_last (bb);
4129 stmt = bsi_end_p (bsi) ? NULL : bsi_stmt (bsi);
4131 switch (stmt ? TREE_CODE (stmt) : ERROR_MARK)
4134 stmt = (e->flags & EDGE_TRUE_VALUE
4135 ? COND_EXPR_THEN (stmt)
4136 : COND_EXPR_ELSE (stmt));
4137 GOTO_DESTINATION (stmt) = label;
4141 /* No non-abnormal edges should lead from a non-simple goto, and
4142 simple ones should be represented implicitly. */
4147 tree vec = SWITCH_LABELS (stmt);
4148 size_t i, n = TREE_VEC_LENGTH (vec);
4150 for (i = 0; i < n; ++i)
4152 tree elt = TREE_VEC_ELT (vec, i);
4153 if (label_to_block (CASE_LABEL (elt)) == e->dest)
4154 CASE_LABEL (elt) = label;
4161 e->flags |= EDGE_FALLTHRU;
4165 /* Otherwise it must be a fallthru edge, and we don't need to
4166 do anything besides redirecting it. */
4167 gcc_assert (e->flags & EDGE_FALLTHRU);
4171 /* Update/insert PHI nodes as necessary. */
4173 /* Now update the edges in the CFG. */
4174 e = ssa_redirect_edge (e, dest);
4180 /* Simple wrapper, as we can always redirect fallthru edges. */
4183 tree_redirect_edge_and_branch_force (edge e, basic_block dest)
4185 e = tree_redirect_edge_and_branch (e, dest);
4192 /* Splits basic block BB after statement STMT (but at least after the
4193 labels). If STMT is NULL, BB is split just after the labels. */
4196 tree_split_block (basic_block bb, void *stmt)
4198 block_stmt_iterator bsi, bsi_tgt;
4204 new_bb = create_empty_bb (bb);
4206 /* Redirect the outgoing edges. */
4207 new_bb->succs = bb->succs;
4209 FOR_EACH_EDGE (e, ei, new_bb->succs)
4212 if (stmt && TREE_CODE ((tree) stmt) == LABEL_EXPR)
4215 /* Move everything from BSI to the new basic block. */
4216 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4218 act = bsi_stmt (bsi);
4219 if (TREE_CODE (act) == LABEL_EXPR)
4232 bsi_tgt = bsi_start (new_bb);
4233 while (!bsi_end_p (bsi))
4235 act = bsi_stmt (bsi);
4237 bsi_insert_after (&bsi_tgt, act, BSI_NEW_STMT);
4244 /* Moves basic block BB after block AFTER. */
4247 tree_move_block_after (basic_block bb, basic_block after)
4249 if (bb->prev_bb == after)
4253 link_block (bb, after);
4259 /* Return true if basic_block can be duplicated. */
4262 tree_can_duplicate_bb_p (basic_block bb ATTRIBUTE_UNUSED)
4267 /* Create a duplicate of the basic block BB. NOTE: This does not
4268 preserve SSA form. */
4271 tree_duplicate_bb (basic_block bb)
4274 block_stmt_iterator bsi, bsi_tgt;
4276 ssa_op_iter op_iter;
4278 new_bb = create_empty_bb (EXIT_BLOCK_PTR->prev_bb);
4280 /* First copy the phi nodes. We do not copy phi node arguments here,
4281 since the edges are not ready yet. Keep the chain of phi nodes in
4282 the same order, so that we can add them later. */
4283 for (phi = phi_nodes (bb); phi; phi = TREE_CHAIN (phi))
4285 mark_for_rewrite (PHI_RESULT (phi));
4286 create_phi_node (PHI_RESULT (phi), new_bb);
4288 set_phi_nodes (new_bb, nreverse (phi_nodes (new_bb)));
4290 bsi_tgt = bsi_start (new_bb);
4291 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4293 tree stmt = bsi_stmt (bsi);
4296 if (TREE_CODE (stmt) == LABEL_EXPR)
4299 /* Record the definitions. */
4300 get_stmt_operands (stmt);
4302 FOR_EACH_SSA_TREE_OPERAND (val, stmt, op_iter, SSA_OP_ALL_DEFS)
4303 mark_for_rewrite (val);
4305 copy = unshare_expr (stmt);
4307 /* Copy also the virtual operands. */
4308 get_stmt_ann (copy);
4309 copy_virtual_operands (copy, stmt);
4311 bsi_insert_after (&bsi_tgt, copy, BSI_NEW_STMT);
4317 /* Basic block BB_COPY was created by code duplication. Add phi node
4318 arguments for edges going out of BB_COPY. The blocks that were
4319 duplicated have rbi->duplicated set to one. */
4322 add_phi_args_after_copy_bb (basic_block bb_copy)
4324 basic_block bb, dest;
4327 tree phi, phi_copy, phi_next, def;
4329 bb = bb_copy->rbi->original;
4331 FOR_EACH_EDGE (e_copy, ei, bb_copy->succs)
4333 if (!phi_nodes (e_copy->dest))
4336 if (e_copy->dest->rbi->duplicated)
4337 dest = e_copy->dest->rbi->original;
4339 dest = e_copy->dest;
4341 e = find_edge (bb, dest);
4344 /* During loop unrolling the target of the latch edge is copied.
4345 In this case we are not looking for edge to dest, but to
4346 duplicated block whose original was dest. */
4347 FOR_EACH_EDGE (e, ei, bb->succs)
4348 if (e->dest->rbi->duplicated
4349 && e->dest->rbi->original == dest)
4352 gcc_assert (e != NULL);
4355 for (phi = phi_nodes (e->dest), phi_copy = phi_nodes (e_copy->dest);
4357 phi = phi_next, phi_copy = TREE_CHAIN (phi_copy))
4359 phi_next = TREE_CHAIN (phi);
4361 gcc_assert (PHI_RESULT (phi) == PHI_RESULT (phi_copy));
4362 def = PHI_ARG_DEF_FROM_EDGE (phi, e);
4363 add_phi_arg (&phi_copy, def, e_copy);
4368 /* Blocks in REGION_COPY array of length N_REGION were created by
4369 duplication of basic blocks. Add phi node arguments for edges
4370 going from these blocks. */
4373 add_phi_args_after_copy (basic_block *region_copy, unsigned n_region)
4377 for (i = 0; i < n_region; i++)
4378 region_copy[i]->rbi->duplicated = 1;
4380 for (i = 0; i < n_region; i++)
4381 add_phi_args_after_copy_bb (region_copy[i]);
4383 for (i = 0; i < n_region; i++)
4384 region_copy[i]->rbi->duplicated = 0;
4387 /* Maps the old ssa name FROM_NAME to TO_NAME. */
4389 struct ssa_name_map_entry
4395 /* Hash function for ssa_name_map_entry. */
4398 ssa_name_map_entry_hash (const void *entry)
4400 const struct ssa_name_map_entry *en = entry;
4401 return SSA_NAME_VERSION (en->from_name);
4404 /* Equality function for ssa_name_map_entry. */
4407 ssa_name_map_entry_eq (const void *in_table, const void *ssa_name)
4409 const struct ssa_name_map_entry *en = in_table;
4411 return en->from_name == ssa_name;
4414 /* Allocate duplicates of ssa names in list DEFINITIONS and store the mapping
4418 allocate_ssa_names (bitmap definitions, htab_t *map)
4421 struct ssa_name_map_entry *entry;
4427 *map = htab_create (10, ssa_name_map_entry_hash,
4428 ssa_name_map_entry_eq, free);
4429 EXECUTE_IF_SET_IN_BITMAP (definitions, 0, ver, bi)
4431 name = ssa_name (ver);
4432 slot = htab_find_slot_with_hash (*map, name, SSA_NAME_VERSION (name),
4438 entry = xmalloc (sizeof (struct ssa_name_map_entry));
4439 entry->from_name = name;
4442 entry->to_name = duplicate_ssa_name (name, SSA_NAME_DEF_STMT (name));
4446 /* Rewrite the definition DEF in statement STMT to new ssa name as specified
4447 by the mapping MAP. */
4450 rewrite_to_new_ssa_names_def (def_operand_p def, tree stmt, htab_t map)
4452 tree name = DEF_FROM_PTR (def);
4453 struct ssa_name_map_entry *entry;
4455 gcc_assert (TREE_CODE (name) == SSA_NAME);
4457 entry = htab_find_with_hash (map, name, SSA_NAME_VERSION (name));
4461 SET_DEF (def, entry->to_name);
4462 SSA_NAME_DEF_STMT (entry->to_name) = stmt;
4465 /* Rewrite the USE to new ssa name as specified by the mapping MAP. */
4468 rewrite_to_new_ssa_names_use (use_operand_p use, htab_t map)
4470 tree name = USE_FROM_PTR (use);
4471 struct ssa_name_map_entry *entry;
4473 if (TREE_CODE (name) != SSA_NAME)
4476 entry = htab_find_with_hash (map, name, SSA_NAME_VERSION (name));
4480 SET_USE (use, entry->to_name);
4483 /* Rewrite the ssa names in basic block BB to new ones as specified by the
4487 rewrite_to_new_ssa_names_bb (basic_block bb, htab_t map)
4493 block_stmt_iterator bsi;
4497 v_may_def_optype v_may_defs;
4498 v_must_def_optype v_must_defs;
4501 FOR_EACH_EDGE (e, ei, bb->preds)
4502 if (e->flags & EDGE_ABNORMAL)
4505 for (phi = phi_nodes (bb); phi; phi = TREE_CHAIN (phi))
4507 rewrite_to_new_ssa_names_def (PHI_RESULT_PTR (phi), phi, map);
4509 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (PHI_RESULT (phi)) = 1;
4512 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4514 stmt = bsi_stmt (bsi);
4515 get_stmt_operands (stmt);
4516 ann = stmt_ann (stmt);
4518 uses = USE_OPS (ann);
4519 for (i = 0; i < NUM_USES (uses); i++)
4520 rewrite_to_new_ssa_names_use (USE_OP_PTR (uses, i), map);
4522 defs = DEF_OPS (ann);
4523 for (i = 0; i < NUM_DEFS (defs); i++)
4524 rewrite_to_new_ssa_names_def (DEF_OP_PTR (defs, i), stmt, map);
4526 vuses = VUSE_OPS (ann);
4527 for (i = 0; i < NUM_VUSES (vuses); i++)
4528 rewrite_to_new_ssa_names_use (VUSE_OP_PTR (vuses, i), map);
4530 v_may_defs = V_MAY_DEF_OPS (ann);
4531 for (i = 0; i < NUM_V_MAY_DEFS (v_may_defs); i++)
4533 rewrite_to_new_ssa_names_use
4534 (V_MAY_DEF_OP_PTR (v_may_defs, i), map);
4535 rewrite_to_new_ssa_names_def
4536 (V_MAY_DEF_RESULT_PTR (v_may_defs, i), stmt, map);
4539 v_must_defs = V_MUST_DEF_OPS (ann);
4540 for (i = 0; i < NUM_V_MUST_DEFS (v_must_defs); i++)
4541 rewrite_to_new_ssa_names_def
4542 (V_MUST_DEF_OP_PTR (v_must_defs, i), stmt, map);
4545 FOR_EACH_EDGE (e, ei, bb->succs)
4546 for (phi = phi_nodes (e->dest); phi; phi = TREE_CHAIN (phi))
4548 rewrite_to_new_ssa_names_use
4549 (PHI_ARG_DEF_PTR_FROM_EDGE (phi, e), map);
4551 if (e->flags & EDGE_ABNORMAL)
4553 tree op = PHI_ARG_DEF_FROM_EDGE (phi, e);
4554 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op) = 1;
4559 /* Rewrite the ssa names in N_REGION blocks REGION to the new ones as specified
4560 by the mapping MAP. */
4563 rewrite_to_new_ssa_names (basic_block *region, unsigned n_region, htab_t map)
4567 for (r = 0; r < n_region; r++)
4568 rewrite_to_new_ssa_names_bb (region[r], map);
4571 /* Duplicates a REGION (set of N_REGION basic blocks) with just a single
4572 important exit edge EXIT. By important we mean that no SSA name defined
4573 inside region is live over the other exit edges of the region. All entry
4574 edges to the region must go to ENTRY->dest. The edge ENTRY is redirected
4575 to the duplicate of the region. SSA form, dominance and loop information
4576 is updated. The new basic blocks are stored to REGION_COPY in the same
4577 order as they had in REGION, provided that REGION_COPY is not NULL.
4578 The function returns false if it is unable to copy the region,
4582 tree_duplicate_sese_region (edge entry, edge exit,
4583 basic_block *region, unsigned n_region,
4584 basic_block *region_copy)
4586 unsigned i, n_doms, ver;
4587 bool free_region_copy = false, copying_header = false;
4588 struct loop *loop = entry->dest->loop_father;
4593 htab_t ssa_name_map = NULL;
4597 if (!can_copy_bbs_p (region, n_region))
4600 /* Some sanity checking. Note that we do not check for all possible
4601 missuses of the functions. I.e. if you ask to copy something weird,
4602 it will work, but the state of structures probably will not be
4605 for (i = 0; i < n_region; i++)
4607 /* We do not handle subloops, i.e. all the blocks must belong to the
4609 if (region[i]->loop_father != loop)
4612 if (region[i] != entry->dest
4613 && region[i] == loop->header)
4619 /* In case the function is used for loop header copying (which is the primary
4620 use), ensure that EXIT and its copy will be new latch and entry edges. */
4621 if (loop->header == entry->dest)
4623 copying_header = true;
4624 loop->copy = loop->outer;
4626 if (!dominated_by_p (CDI_DOMINATORS, loop->latch, exit->src))
4629 for (i = 0; i < n_region; i++)
4630 if (region[i] != exit->src
4631 && dominated_by_p (CDI_DOMINATORS, region[i], exit->src))
4637 region_copy = xmalloc (sizeof (basic_block) * n_region);
4638 free_region_copy = true;
4641 gcc_assert (!any_marked_for_rewrite_p ());
4643 /* Record blocks outside the region that are duplicated by something
4645 doms = xmalloc (sizeof (basic_block) * n_basic_blocks);
4646 n_doms = get_dominated_by_region (CDI_DOMINATORS, region, n_region, doms);
4648 copy_bbs (region, n_region, region_copy, &exit, 1, &exit_copy, loop);
4649 definitions = marked_ssa_names ();
4653 loop->header = exit->dest;
4654 loop->latch = exit->src;
4657 /* Redirect the entry and add the phi node arguments. */
4658 redirected = redirect_edge_and_branch (entry, entry->dest->rbi->copy);
4659 gcc_assert (redirected != NULL);
4660 for (phi = phi_nodes (entry->dest), var = PENDING_STMT (entry);
4662 phi = TREE_CHAIN (phi), var = TREE_CHAIN (var))
4663 add_phi_arg (&phi, TREE_VALUE (var), entry);
4664 PENDING_STMT (entry) = NULL;
4666 /* Concerning updating of dominators: We must recount dominators
4667 for entry block and its copy. Anything that is outside of the region, but
4668 was dominated by something inside needs recounting as well. */
4669 set_immediate_dominator (CDI_DOMINATORS, entry->dest, entry->src);
4670 doms[n_doms++] = entry->dest->rbi->original;
4671 iterate_fix_dominators (CDI_DOMINATORS, doms, n_doms);
4674 /* Add the other phi node arguments. */
4675 add_phi_args_after_copy (region_copy, n_region);
4677 /* Add phi nodes for definitions at exit. TODO -- once we have immediate
4678 uses, it should be possible to emit phi nodes just for definitions that
4679 are used outside region. */
4680 EXECUTE_IF_SET_IN_BITMAP (definitions, 0, ver, bi)
4682 tree name = ssa_name (ver);
4684 phi = create_phi_node (name, exit->dest);
4685 add_phi_arg (&phi, name, exit);
4686 add_phi_arg (&phi, name, exit_copy);
4688 SSA_NAME_DEF_STMT (name) = phi;
4691 /* And create new definitions inside region and its copy. TODO -- once we
4692 have immediate uses, it might be better to leave definitions in region
4693 unchanged, create new ssa names for phi nodes on exit, and rewrite
4694 the uses, to avoid changing the copied region. */
4695 allocate_ssa_names (definitions, &ssa_name_map);
4696 rewrite_to_new_ssa_names (region, n_region, ssa_name_map);
4697 allocate_ssa_names (definitions, &ssa_name_map);
4698 rewrite_to_new_ssa_names (region_copy, n_region, ssa_name_map);
4699 htab_delete (ssa_name_map);
4701 if (free_region_copy)
4704 unmark_all_for_rewrite ();
4705 BITMAP_XFREE (definitions);
4710 /* Dump FUNCTION_DECL FN to file FILE using FLAGS (see TDF_* in tree.h) */
4713 dump_function_to_file (tree fn, FILE *file, int flags)
4715 tree arg, vars, var;
4716 bool ignore_topmost_bind = false, any_var = false;
4720 fprintf (file, "%s (", lang_hooks.decl_printable_name (fn, 2));
4722 arg = DECL_ARGUMENTS (fn);
4725 print_generic_expr (file, arg, dump_flags);
4726 if (TREE_CHAIN (arg))
4727 fprintf (file, ", ");
4728 arg = TREE_CHAIN (arg);
4730 fprintf (file, ")\n");
4732 if (flags & TDF_RAW)
4734 dump_node (fn, TDF_SLIM | flags, file);
4738 /* When GIMPLE is lowered, the variables are no longer available in
4739 BIND_EXPRs, so display them separately. */
4740 if (cfun && cfun->unexpanded_var_list)
4742 ignore_topmost_bind = true;
4744 fprintf (file, "{\n");
4745 for (vars = cfun->unexpanded_var_list; vars; vars = TREE_CHAIN (vars))
4747 var = TREE_VALUE (vars);
4749 print_generic_decl (file, var, flags);
4750 fprintf (file, "\n");
4756 if (basic_block_info)
4758 /* Make a CFG based dump. */
4759 check_bb_profile (ENTRY_BLOCK_PTR, file);
4760 if (!ignore_topmost_bind)
4761 fprintf (file, "{\n");
4763 if (any_var && n_basic_blocks)
4764 fprintf (file, "\n");
4767 dump_generic_bb (file, bb, 2, flags);
4769 fprintf (file, "}\n");
4770 check_bb_profile (EXIT_BLOCK_PTR, file);
4776 /* Make a tree based dump. */
4777 chain = DECL_SAVED_TREE (fn);
4779 if (TREE_CODE (chain) == BIND_EXPR)
4781 if (ignore_topmost_bind)
4783 chain = BIND_EXPR_BODY (chain);
4791 if (!ignore_topmost_bind)
4792 fprintf (file, "{\n");
4797 fprintf (file, "\n");
4799 print_generic_stmt_indented (file, chain, flags, indent);
4800 if (ignore_topmost_bind)
4801 fprintf (file, "}\n");
4804 fprintf (file, "\n\n");
4808 /* Pretty print of the loops intermediate representation. */
4809 static void print_loop (FILE *, struct loop *, int);
4810 static void print_pred_bbs (FILE *, basic_block bb);
4811 static void print_succ_bbs (FILE *, basic_block bb);
4814 /* Print the predecessors indexes of edge E on FILE. */
4817 print_pred_bbs (FILE *file, basic_block bb)
4822 FOR_EACH_EDGE (e, ei, bb->preds)
4823 fprintf (file, "bb_%d", e->src->index);
4827 /* Print the successors indexes of edge E on FILE. */
4830 print_succ_bbs (FILE *file, basic_block bb)
4835 FOR_EACH_EDGE (e, ei, bb->succs)
4836 fprintf (file, "bb_%d", e->src->index);
4840 /* Pretty print LOOP on FILE, indented INDENT spaces. */
4843 print_loop (FILE *file, struct loop *loop, int indent)
4851 s_indent = (char *) alloca ((size_t) indent + 1);
4852 memset ((void *) s_indent, ' ', (size_t) indent);
4853 s_indent[indent] = '\0';
4855 /* Print the loop's header. */
4856 fprintf (file, "%sloop_%d\n", s_indent, loop->num);
4858 /* Print the loop's body. */
4859 fprintf (file, "%s{\n", s_indent);
4861 if (bb->loop_father == loop)
4863 /* Print the basic_block's header. */
4864 fprintf (file, "%s bb_%d (preds = {", s_indent, bb->index);
4865 print_pred_bbs (file, bb);
4866 fprintf (file, "}, succs = {");
4867 print_succ_bbs (file, bb);
4868 fprintf (file, "})\n");
4870 /* Print the basic_block's body. */
4871 fprintf (file, "%s {\n", s_indent);
4872 tree_dump_bb (bb, file, indent + 4);
4873 fprintf (file, "%s }\n", s_indent);
4876 print_loop (file, loop->inner, indent + 2);
4877 fprintf (file, "%s}\n", s_indent);
4878 print_loop (file, loop->next, indent);
4882 /* Follow a CFG edge from the entry point of the program, and on entry
4883 of a loop, pretty print the loop structure on FILE. */
4886 print_loop_ir (FILE *file)
4890 bb = BASIC_BLOCK (0);
4891 if (bb && bb->loop_father)
4892 print_loop (file, bb->loop_father, 0);
4896 /* Debugging loops structure at tree level. */
4899 debug_loop_ir (void)
4901 print_loop_ir (stderr);
4905 /* Return true if BB ends with a call, possibly followed by some
4906 instructions that must stay with the call. Return false,
4910 tree_block_ends_with_call_p (basic_block bb)
4912 block_stmt_iterator bsi = bsi_last (bb);
4913 return get_call_expr_in (bsi_stmt (bsi)) != NULL;
4917 /* Return true if BB ends with a conditional branch. Return false,
4921 tree_block_ends_with_condjump_p (basic_block bb)
4923 tree stmt = tsi_stmt (bsi_last (bb).tsi);
4924 return (TREE_CODE (stmt) == COND_EXPR);
4928 /* Return true if we need to add fake edge to exit at statement T.
4929 Helper function for tree_flow_call_edges_add. */
4932 need_fake_edge_p (tree t)
4936 /* NORETURN and LONGJMP calls already have an edge to exit.
4937 CONST, PURE and ALWAYS_RETURN calls do not need one.
4938 We don't currently check for CONST and PURE here, although
4939 it would be a good idea, because those attributes are
4940 figured out from the RTL in mark_constant_function, and
4941 the counter incrementation code from -fprofile-arcs
4942 leads to different results from -fbranch-probabilities. */
4943 call = get_call_expr_in (t);
4945 && !(call_expr_flags (call) &
4946 (ECF_NORETURN | ECF_LONGJMP | ECF_ALWAYS_RETURN)))
4949 if (TREE_CODE (t) == ASM_EXPR
4950 && (ASM_VOLATILE_P (t) || ASM_INPUT_P (t)))
4957 /* Add fake edges to the function exit for any non constant and non
4958 noreturn calls, volatile inline assembly in the bitmap of blocks
4959 specified by BLOCKS or to the whole CFG if BLOCKS is zero. Return
4960 the number of blocks that were split.
4962 The goal is to expose cases in which entering a basic block does
4963 not imply that all subsequent instructions must be executed. */
4966 tree_flow_call_edges_add (sbitmap blocks)
4969 int blocks_split = 0;
4970 int last_bb = last_basic_block;
4971 bool check_last_block = false;
4973 if (n_basic_blocks == 0)
4977 check_last_block = true;
4979 check_last_block = TEST_BIT (blocks, EXIT_BLOCK_PTR->prev_bb->index);
4981 /* In the last basic block, before epilogue generation, there will be
4982 a fallthru edge to EXIT. Special care is required if the last insn
4983 of the last basic block is a call because make_edge folds duplicate
4984 edges, which would result in the fallthru edge also being marked
4985 fake, which would result in the fallthru edge being removed by
4986 remove_fake_edges, which would result in an invalid CFG.
4988 Moreover, we can't elide the outgoing fake edge, since the block
4989 profiler needs to take this into account in order to solve the minimal
4990 spanning tree in the case that the call doesn't return.
4992 Handle this by adding a dummy instruction in a new last basic block. */
4993 if (check_last_block)
4996 basic_block bb = EXIT_BLOCK_PTR->prev_bb;
4997 block_stmt_iterator bsi = bsi_last (bb);
4999 if (!bsi_end_p (bsi))
5002 if (need_fake_edge_p (t))
5006 FOR_EACH_EDGE (e, ei, bb->succs)
5007 if (e->dest == EXIT_BLOCK_PTR)
5009 bsi_insert_on_edge (e, build_empty_stmt ());
5010 bsi_commit_edge_inserts ((int *)NULL);
5016 /* Now add fake edges to the function exit for any non constant
5017 calls since there is no way that we can determine if they will
5019 for (i = 0; i < last_bb; i++)
5021 basic_block bb = BASIC_BLOCK (i);
5022 block_stmt_iterator bsi;
5023 tree stmt, last_stmt;
5028 if (blocks && !TEST_BIT (blocks, i))
5031 bsi = bsi_last (bb);
5032 if (!bsi_end_p (bsi))
5034 last_stmt = bsi_stmt (bsi);
5037 stmt = bsi_stmt (bsi);
5038 if (need_fake_edge_p (stmt))
5041 /* The handling above of the final block before the
5042 epilogue should be enough to verify that there is
5043 no edge to the exit block in CFG already.
5044 Calling make_edge in such case would cause us to
5045 mark that edge as fake and remove it later. */
5046 #ifdef ENABLE_CHECKING
5047 if (stmt == last_stmt)
5050 FOR_EACH_EDGE (e, ei, bb->succs)
5051 gcc_assert (e->dest != EXIT_BLOCK_PTR);
5055 /* Note that the following may create a new basic block
5056 and renumber the existing basic blocks. */
5057 if (stmt != last_stmt)
5059 e = split_block (bb, stmt);
5063 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
5067 while (!bsi_end_p (bsi));
5072 verify_flow_info ();
5074 return blocks_split;
5078 tree_purge_dead_eh_edges (basic_block bb)
5080 bool changed = false;
5083 tree stmt = last_stmt (bb);
5085 if (stmt && tree_can_throw_internal (stmt))
5088 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
5090 if (e->flags & EDGE_EH)
5092 ssa_remove_edge (e);
5103 tree_purge_all_dead_eh_edges (bitmap blocks)
5105 bool changed = false;
5109 EXECUTE_IF_SET_IN_BITMAP (blocks, 0, i, bi)
5111 changed |= tree_purge_dead_eh_edges (BASIC_BLOCK (i));
5117 struct cfg_hooks tree_cfg_hooks = {
5119 tree_verify_flow_info,
5120 tree_dump_bb, /* dump_bb */
5121 create_bb, /* create_basic_block */
5122 tree_redirect_edge_and_branch,/* redirect_edge_and_branch */
5123 tree_redirect_edge_and_branch_force,/* redirect_edge_and_branch_force */
5124 remove_bb, /* delete_basic_block */
5125 tree_split_block, /* split_block */
5126 tree_move_block_after, /* move_block_after */
5127 tree_can_merge_blocks_p, /* can_merge_blocks_p */
5128 tree_merge_blocks, /* merge_blocks */
5129 tree_predict_edge, /* predict_edge */
5130 tree_predicted_by_p, /* predicted_by_p */
5131 tree_can_duplicate_bb_p, /* can_duplicate_block_p */
5132 tree_duplicate_bb, /* duplicate_block */
5133 tree_split_edge, /* split_edge */
5134 tree_make_forwarder_block, /* make_forward_block */
5135 NULL, /* tidy_fallthru_edge */
5136 tree_block_ends_with_call_p, /* block_ends_with_call_p */
5137 tree_block_ends_with_condjump_p, /* block_ends_with_condjump_p */
5138 tree_flow_call_edges_add /* flow_call_edges_add */
5142 /* Split all critical edges. */
5145 split_critical_edges (void)
5153 FOR_EACH_EDGE (e, ei, bb->succs)
5154 if (EDGE_CRITICAL_P (e) && !(e->flags & EDGE_ABNORMAL))
5161 struct tree_opt_pass pass_split_crit_edges =
5163 "crited", /* name */
5165 split_critical_edges, /* execute */
5168 0, /* static_pass_number */
5169 TV_TREE_SPLIT_EDGES, /* tv_id */
5170 PROP_cfg, /* properties required */
5171 PROP_no_crit_edges, /* properties_provided */
5172 0, /* properties_destroyed */
5173 0, /* todo_flags_start */
5174 TODO_dump_func, /* todo_flags_finish */
5179 /* Return EXP if it is a valid GIMPLE rvalue, else gimplify it into
5180 a temporary, make sure and register it to be renamed if necessary,
5181 and finally return the temporary. Put the statements to compute
5182 EXP before the current statement in BSI. */
5185 gimplify_val (block_stmt_iterator *bsi, tree type, tree exp)
5187 tree t, new_stmt, orig_stmt;
5189 if (is_gimple_val (exp))
5192 t = make_rename_temp (type, NULL);
5193 new_stmt = build (MODIFY_EXPR, type, t, exp);
5195 orig_stmt = bsi_stmt (*bsi);
5196 SET_EXPR_LOCUS (new_stmt, EXPR_LOCUS (orig_stmt));
5197 TREE_BLOCK (new_stmt) = TREE_BLOCK (orig_stmt);
5199 bsi_insert_before (bsi, new_stmt, BSI_SAME_STMT);
5204 /* Build a ternary operation and gimplify it. Emit code before BSI.
5205 Return the gimple_val holding the result. */
5208 gimplify_build3 (block_stmt_iterator *bsi, enum tree_code code,
5209 tree type, tree a, tree b, tree c)
5213 ret = fold (build3 (code, type, a, b, c));
5216 return gimplify_val (bsi, type, ret);
5219 /* Build a binary operation and gimplify it. Emit code before BSI.
5220 Return the gimple_val holding the result. */
5223 gimplify_build2 (block_stmt_iterator *bsi, enum tree_code code,
5224 tree type, tree a, tree b)
5228 ret = fold (build2 (code, type, a, b));
5231 return gimplify_val (bsi, type, ret);
5234 /* Build a unary operation and gimplify it. Emit code before BSI.
5235 Return the gimple_val holding the result. */
5238 gimplify_build1 (block_stmt_iterator *bsi, enum tree_code code, tree type,
5243 ret = fold (build1 (code, type, a));
5246 return gimplify_val (bsi, type, ret);
5251 /* Emit return warnings. */
5254 execute_warn_function_return (void)
5256 #ifdef USE_MAPPED_LOCATION
5257 source_location location;
5265 if (warn_missing_noreturn
5266 && !TREE_THIS_VOLATILE (cfun->decl)
5267 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) == 0
5268 && !lang_hooks.function.missing_noreturn_ok_p (cfun->decl))
5269 warning ("%Jfunction might be possible candidate for "
5270 "attribute %<noreturn%>",
5273 /* If we have a path to EXIT, then we do return. */
5274 if (TREE_THIS_VOLATILE (cfun->decl)
5275 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) > 0)
5277 #ifdef USE_MAPPED_LOCATION
5278 location = UNKNOWN_LOCATION;
5282 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
5284 last = last_stmt (e->src);
5285 if (TREE_CODE (last) == RETURN_EXPR
5286 #ifdef USE_MAPPED_LOCATION
5287 && (location = EXPR_LOCATION (last)) != UNKNOWN_LOCATION)
5289 && (locus = EXPR_LOCUS (last)) != NULL)
5293 #ifdef USE_MAPPED_LOCATION
5294 if (location == UNKNOWN_LOCATION)
5295 location = cfun->function_end_locus;
5296 warning ("%H%<noreturn%> function does return", &location);
5299 locus = &cfun->function_end_locus;
5300 warning ("%H%<noreturn%> function does return", locus);
5304 /* If we see "return;" in some basic block, then we do reach the end
5305 without returning a value. */
5306 else if (warn_return_type
5307 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) > 0
5308 && !VOID_TYPE_P (TREE_TYPE (TREE_TYPE (cfun->decl))))
5310 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
5312 tree last = last_stmt (e->src);
5313 if (TREE_CODE (last) == RETURN_EXPR
5314 && TREE_OPERAND (last, 0) == NULL)
5316 #ifdef USE_MAPPED_LOCATION
5317 location = EXPR_LOCATION (last);
5318 if (location == UNKNOWN_LOCATION)
5319 location = cfun->function_end_locus;
5320 warning ("%Hcontrol reaches end of non-void function", &location);
5322 locus = EXPR_LOCUS (last);
5324 locus = &cfun->function_end_locus;
5325 warning ("%Hcontrol reaches end of non-void function", locus);
5334 /* Given a basic block B which ends with a conditional and has
5335 precisely two successors, determine which of the edges is taken if
5336 the conditional is true and which is taken if the conditional is
5337 false. Set TRUE_EDGE and FALSE_EDGE appropriately. */
5340 extract_true_false_edges_from_block (basic_block b,
5344 edge e = EDGE_SUCC (b, 0);
5346 if (e->flags & EDGE_TRUE_VALUE)
5349 *false_edge = EDGE_SUCC (b, 1);
5354 *true_edge = EDGE_SUCC (b, 1);
5358 struct tree_opt_pass pass_warn_function_return =
5362 execute_warn_function_return, /* execute */
5365 0, /* static_pass_number */
5367 PROP_cfg, /* properties_required */
5368 0, /* properties_provided */
5369 0, /* properties_destroyed */
5370 0, /* todo_flags_start */
5371 0, /* todo_flags_finish */
5375 #include "gt-tree-cfg.h"