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)
717 timevar_push (TV_TREE_CLEANUP_CFG);
719 retval = cleanup_control_flow ();
720 retval |= delete_unreachable_blocks ();
722 /* thread_jumps sometimes leaves further transformation
723 opportunities for itself, so iterate on it until nothing
725 while (thread_jumps ())
728 #ifdef ENABLE_CHECKING
731 gcc_assert (!cleanup_control_flow ());
732 gcc_assert (!delete_unreachable_blocks ());
736 /* Merging the blocks creates no new opportunities for the other
737 optimizations, so do it here. */
742 #ifdef ENABLE_CHECKING
745 timevar_pop (TV_TREE_CLEANUP_CFG);
750 /* Cleanup useless labels in basic blocks. This is something we wish
751 to do early because it allows us to group case labels before creating
752 the edges for the CFG, and it speeds up block statement iterators in
754 We only run this pass once, running it more than once is probably not
757 /* A map from basic block index to the leading label of that block. */
758 static tree *label_for_bb;
760 /* Callback for for_each_eh_region. Helper for cleanup_dead_labels. */
762 update_eh_label (struct eh_region *region)
764 tree old_label = get_eh_region_tree_label (region);
768 basic_block bb = label_to_block (old_label);
770 /* ??? After optimizing, there may be EH regions with labels
771 that have already been removed from the function body, so
772 there is no basic block for them. */
776 new_label = label_for_bb[bb->index];
777 set_eh_region_tree_label (region, new_label);
781 /* Given LABEL return the first label in the same basic block. */
783 main_block_label (tree label)
785 basic_block bb = label_to_block (label);
787 /* label_to_block possibly inserted undefined label into the chain. */
788 if (!label_for_bb[bb->index])
789 label_for_bb[bb->index] = label;
790 return label_for_bb[bb->index];
793 /* Cleanup redundant labels. This is a three-steo process:
794 1) Find the leading label for each block.
795 2) Redirect all references to labels to the leading labels.
796 3) Cleanup all useless labels. */
799 cleanup_dead_labels (void)
802 label_for_bb = xcalloc (last_basic_block, sizeof (tree));
804 /* Find a suitable label for each block. We use the first user-defined
805 label is there is one, or otherwise just the first label we see. */
808 block_stmt_iterator i;
810 for (i = bsi_start (bb); !bsi_end_p (i); bsi_next (&i))
812 tree label, stmt = bsi_stmt (i);
814 if (TREE_CODE (stmt) != LABEL_EXPR)
817 label = LABEL_EXPR_LABEL (stmt);
819 /* If we have not yet seen a label for the current block,
820 remember this one and see if there are more labels. */
821 if (! label_for_bb[bb->index])
823 label_for_bb[bb->index] = label;
827 /* If we did see a label for the current block already, but it
828 is an artificially created label, replace it if the current
829 label is a user defined label. */
830 if (! DECL_ARTIFICIAL (label)
831 && DECL_ARTIFICIAL (label_for_bb[bb->index]))
833 label_for_bb[bb->index] = label;
839 /* Now redirect all jumps/branches to the selected label.
840 First do so for each block ending in a control statement. */
843 tree stmt = last_stmt (bb);
847 switch (TREE_CODE (stmt))
851 tree true_branch, false_branch;
853 true_branch = COND_EXPR_THEN (stmt);
854 false_branch = COND_EXPR_ELSE (stmt);
856 GOTO_DESTINATION (true_branch)
857 = main_block_label (GOTO_DESTINATION (true_branch));
858 GOTO_DESTINATION (false_branch)
859 = main_block_label (GOTO_DESTINATION (false_branch));
867 tree vec = SWITCH_LABELS (stmt);
868 size_t n = TREE_VEC_LENGTH (vec);
870 /* Replace all destination labels. */
871 for (i = 0; i < n; ++i)
872 CASE_LABEL (TREE_VEC_ELT (vec, i))
873 = main_block_label (CASE_LABEL (TREE_VEC_ELT (vec, i)));
878 /* We have to handle GOTO_EXPRs until they're removed, and we don't
879 remove them until after we've created the CFG edges. */
881 if (! computed_goto_p (stmt))
883 GOTO_DESTINATION (stmt)
884 = main_block_label (GOTO_DESTINATION (stmt));
893 for_each_eh_region (update_eh_label);
895 /* Finally, purge dead labels. All user-defined labels and labels that
896 can be the target of non-local gotos are preserved. */
899 block_stmt_iterator i;
900 tree label_for_this_bb = label_for_bb[bb->index];
902 if (! label_for_this_bb)
905 for (i = bsi_start (bb); !bsi_end_p (i); )
907 tree label, stmt = bsi_stmt (i);
909 if (TREE_CODE (stmt) != LABEL_EXPR)
912 label = LABEL_EXPR_LABEL (stmt);
914 if (label == label_for_this_bb
915 || ! DECL_ARTIFICIAL (label)
916 || DECL_NONLOCAL (label))
926 /* Look for blocks ending in a multiway branch (a SWITCH_EXPR in GIMPLE),
927 and scan the sorted vector of cases. Combine the ones jumping to the
929 Eg. three separate entries 1: 2: 3: become one entry 1..3: */
932 group_case_labels (void)
938 tree stmt = last_stmt (bb);
939 if (stmt && TREE_CODE (stmt) == SWITCH_EXPR)
941 tree labels = SWITCH_LABELS (stmt);
942 int old_size = TREE_VEC_LENGTH (labels);
943 int i, j, new_size = old_size;
944 tree default_case = TREE_VEC_ELT (labels, old_size - 1);
947 /* The default label is always the last case in a switch
948 statement after gimplification. */
949 default_label = CASE_LABEL (default_case);
951 /* Look for possible opportunities to merge cases.
952 Ignore the last element of the label vector because it
953 must be the default case. */
955 while (i < old_size - 2)
957 tree base_case, base_label, base_high, type;
958 base_case = TREE_VEC_ELT (labels, i);
960 gcc_assert (base_case);
961 base_label = CASE_LABEL (base_case);
963 /* Discard cases that have the same destination as the
965 if (base_label == default_label)
967 TREE_VEC_ELT (labels, i) = NULL_TREE;
973 type = TREE_TYPE (CASE_LOW (base_case));
974 base_high = CASE_HIGH (base_case) ?
975 CASE_HIGH (base_case) : CASE_LOW (base_case);
977 /* Try to merge case labels. Break out when we reach the end
978 of the label vector or when we cannot merge the next case
979 label with the current one. */
980 while (i < old_size - 2)
982 tree merge_case = TREE_VEC_ELT (labels, ++i);
983 tree merge_label = CASE_LABEL (merge_case);
984 tree t = int_const_binop (PLUS_EXPR, base_high,
985 integer_one_node, 1);
987 /* Merge the cases if they jump to the same place,
988 and their ranges are consecutive. */
989 if (merge_label == base_label
990 && tree_int_cst_equal (CASE_LOW (merge_case), t))
992 base_high = CASE_HIGH (merge_case) ?
993 CASE_HIGH (merge_case) : CASE_LOW (merge_case);
994 CASE_HIGH (base_case) = base_high;
995 TREE_VEC_ELT (labels, i) = NULL_TREE;
1003 /* Compress the case labels in the label vector, and adjust the
1004 length of the vector. */
1005 for (i = 0, j = 0; i < new_size; i++)
1007 while (! TREE_VEC_ELT (labels, j))
1009 TREE_VEC_ELT (labels, i) = TREE_VEC_ELT (labels, j++);
1011 TREE_VEC_LENGTH (labels) = new_size;
1016 /* Checks whether we can merge block B into block A. */
1019 tree_can_merge_blocks_p (basic_block a, basic_block b)
1022 block_stmt_iterator bsi;
1024 if (EDGE_COUNT (a->succs) != 1)
1027 if (EDGE_SUCC (a, 0)->flags & EDGE_ABNORMAL)
1030 if (EDGE_SUCC (a, 0)->dest != b)
1033 if (b == EXIT_BLOCK_PTR)
1036 if (EDGE_COUNT (b->preds) > 1)
1039 /* If A ends by a statement causing exceptions or something similar, we
1040 cannot merge the blocks. */
1041 stmt = last_stmt (a);
1042 if (stmt && stmt_ends_bb_p (stmt))
1045 /* Do not allow a block with only a non-local label to be merged. */
1046 if (stmt && TREE_CODE (stmt) == LABEL_EXPR
1047 && DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)))
1050 /* There may be no phi nodes at the start of b. Most of these degenerate
1051 phi nodes should be cleaned up by kill_redundant_phi_nodes. */
1055 /* Do not remove user labels. */
1056 for (bsi = bsi_start (b); !bsi_end_p (bsi); bsi_next (&bsi))
1058 stmt = bsi_stmt (bsi);
1059 if (TREE_CODE (stmt) != LABEL_EXPR)
1061 if (!DECL_ARTIFICIAL (LABEL_EXPR_LABEL (stmt)))
1069 /* Merge block B into block A. */
1072 tree_merge_blocks (basic_block a, basic_block b)
1074 block_stmt_iterator bsi;
1075 tree_stmt_iterator last;
1078 fprintf (dump_file, "Merging blocks %d and %d\n", a->index, b->index);
1080 /* Ensure that B follows A. */
1081 move_block_after (b, a);
1083 gcc_assert (EDGE_SUCC (a, 0)->flags & EDGE_FALLTHRU);
1084 gcc_assert (!last_stmt (a) || !stmt_ends_bb_p (last_stmt (a)));
1086 /* Remove labels from B and set bb_for_stmt to A for other statements. */
1087 for (bsi = bsi_start (b); !bsi_end_p (bsi);)
1089 if (TREE_CODE (bsi_stmt (bsi)) == LABEL_EXPR)
1093 set_bb_for_stmt (bsi_stmt (bsi), a);
1098 /* Merge the chains. */
1099 last = tsi_last (a->stmt_list);
1100 tsi_link_after (&last, b->stmt_list, TSI_NEW_STMT);
1101 b->stmt_list = NULL;
1105 /* Walk the function tree removing unnecessary statements.
1107 * Empty statement nodes are removed
1109 * Unnecessary TRY_FINALLY and TRY_CATCH blocks are removed
1111 * Unnecessary COND_EXPRs are removed
1113 * Some unnecessary BIND_EXPRs are removed
1115 Clearly more work could be done. The trick is doing the analysis
1116 and removal fast enough to be a net improvement in compile times.
1118 Note that when we remove a control structure such as a COND_EXPR
1119 BIND_EXPR, or TRY block, we will need to repeat this optimization pass
1120 to ensure we eliminate all the useless code. */
1131 static void remove_useless_stmts_1 (tree *, struct rus_data *);
1134 remove_useless_stmts_warn_notreached (tree stmt)
1136 if (EXPR_HAS_LOCATION (stmt))
1138 location_t loc = EXPR_LOCATION (stmt);
1139 warning ("%Hwill never be executed", &loc);
1143 switch (TREE_CODE (stmt))
1145 case STATEMENT_LIST:
1147 tree_stmt_iterator i;
1148 for (i = tsi_start (stmt); !tsi_end_p (i); tsi_next (&i))
1149 if (remove_useless_stmts_warn_notreached (tsi_stmt (i)))
1155 if (remove_useless_stmts_warn_notreached (COND_EXPR_COND (stmt)))
1157 if (remove_useless_stmts_warn_notreached (COND_EXPR_THEN (stmt)))
1159 if (remove_useless_stmts_warn_notreached (COND_EXPR_ELSE (stmt)))
1163 case TRY_FINALLY_EXPR:
1164 case TRY_CATCH_EXPR:
1165 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt, 0)))
1167 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt, 1)))
1172 return remove_useless_stmts_warn_notreached (CATCH_BODY (stmt));
1173 case EH_FILTER_EXPR:
1174 return remove_useless_stmts_warn_notreached (EH_FILTER_FAILURE (stmt));
1176 return remove_useless_stmts_warn_notreached (BIND_EXPR_BLOCK (stmt));
1179 /* Not a live container. */
1187 remove_useless_stmts_cond (tree *stmt_p, struct rus_data *data)
1189 tree then_clause, else_clause, cond;
1190 bool save_has_label, then_has_label, else_has_label;
1192 save_has_label = data->has_label;
1193 data->has_label = false;
1194 data->last_goto = NULL;
1196 remove_useless_stmts_1 (&COND_EXPR_THEN (*stmt_p), data);
1198 then_has_label = data->has_label;
1199 data->has_label = false;
1200 data->last_goto = NULL;
1202 remove_useless_stmts_1 (&COND_EXPR_ELSE (*stmt_p), data);
1204 else_has_label = data->has_label;
1205 data->has_label = save_has_label | then_has_label | else_has_label;
1208 then_clause = COND_EXPR_THEN (*stmt_p);
1209 else_clause = COND_EXPR_ELSE (*stmt_p);
1210 cond = COND_EXPR_COND (*stmt_p);
1212 /* If neither arm does anything at all, we can remove the whole IF. */
1213 if (!TREE_SIDE_EFFECTS (then_clause) && !TREE_SIDE_EFFECTS (else_clause))
1215 *stmt_p = build_empty_stmt ();
1216 data->repeat = true;
1219 /* If there are no reachable statements in an arm, then we can
1220 zap the entire conditional. */
1221 else if (integer_nonzerop (cond) && !else_has_label)
1223 if (warn_notreached)
1224 remove_useless_stmts_warn_notreached (else_clause);
1225 *stmt_p = then_clause;
1226 data->repeat = true;
1228 else if (integer_zerop (cond) && !then_has_label)
1230 if (warn_notreached)
1231 remove_useless_stmts_warn_notreached (then_clause);
1232 *stmt_p = else_clause;
1233 data->repeat = true;
1236 /* Check a couple of simple things on then/else with single stmts. */
1239 tree then_stmt = expr_only (then_clause);
1240 tree else_stmt = expr_only (else_clause);
1242 /* Notice branches to a common destination. */
1243 if (then_stmt && else_stmt
1244 && TREE_CODE (then_stmt) == GOTO_EXPR
1245 && TREE_CODE (else_stmt) == GOTO_EXPR
1246 && (GOTO_DESTINATION (then_stmt) == GOTO_DESTINATION (else_stmt)))
1248 *stmt_p = then_stmt;
1249 data->repeat = true;
1252 /* If the THEN/ELSE clause merely assigns a value to a variable or
1253 parameter which is already known to contain that value, then
1254 remove the useless THEN/ELSE clause. */
1255 else if (TREE_CODE (cond) == VAR_DECL || TREE_CODE (cond) == PARM_DECL)
1258 && TREE_CODE (else_stmt) == MODIFY_EXPR
1259 && TREE_OPERAND (else_stmt, 0) == cond
1260 && integer_zerop (TREE_OPERAND (else_stmt, 1)))
1261 COND_EXPR_ELSE (*stmt_p) = alloc_stmt_list ();
1263 else if ((TREE_CODE (cond) == EQ_EXPR || TREE_CODE (cond) == NE_EXPR)
1264 && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL
1265 || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL)
1266 && TREE_CONSTANT (TREE_OPERAND (cond, 1)))
1268 tree stmt = (TREE_CODE (cond) == EQ_EXPR
1269 ? then_stmt : else_stmt);
1270 tree *location = (TREE_CODE (cond) == EQ_EXPR
1271 ? &COND_EXPR_THEN (*stmt_p)
1272 : &COND_EXPR_ELSE (*stmt_p));
1275 && TREE_CODE (stmt) == MODIFY_EXPR
1276 && TREE_OPERAND (stmt, 0) == TREE_OPERAND (cond, 0)
1277 && TREE_OPERAND (stmt, 1) == TREE_OPERAND (cond, 1))
1278 *location = alloc_stmt_list ();
1282 /* Protect GOTOs in the arm of COND_EXPRs from being removed. They
1283 would be re-introduced during lowering. */
1284 data->last_goto = NULL;
1289 remove_useless_stmts_tf (tree *stmt_p, struct rus_data *data)
1291 bool save_may_branch, save_may_throw;
1292 bool this_may_branch, this_may_throw;
1294 /* Collect may_branch and may_throw information for the body only. */
1295 save_may_branch = data->may_branch;
1296 save_may_throw = data->may_throw;
1297 data->may_branch = false;
1298 data->may_throw = false;
1299 data->last_goto = NULL;
1301 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 0), data);
1303 this_may_branch = data->may_branch;
1304 this_may_throw = data->may_throw;
1305 data->may_branch |= save_may_branch;
1306 data->may_throw |= save_may_throw;
1307 data->last_goto = NULL;
1309 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 1), data);
1311 /* If the body is empty, then we can emit the FINALLY block without
1312 the enclosing TRY_FINALLY_EXPR. */
1313 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 0)))
1315 *stmt_p = TREE_OPERAND (*stmt_p, 1);
1316 data->repeat = true;
1319 /* If the handler is empty, then we can emit the TRY block without
1320 the enclosing TRY_FINALLY_EXPR. */
1321 else if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 1)))
1323 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1324 data->repeat = true;
1327 /* If the body neither throws, nor branches, then we can safely
1328 string the TRY and FINALLY blocks together. */
1329 else if (!this_may_branch && !this_may_throw)
1331 tree stmt = *stmt_p;
1332 *stmt_p = TREE_OPERAND (stmt, 0);
1333 append_to_statement_list (TREE_OPERAND (stmt, 1), stmt_p);
1334 data->repeat = true;
1340 remove_useless_stmts_tc (tree *stmt_p, struct rus_data *data)
1342 bool save_may_throw, this_may_throw;
1343 tree_stmt_iterator i;
1346 /* Collect may_throw information for the body only. */
1347 save_may_throw = data->may_throw;
1348 data->may_throw = false;
1349 data->last_goto = NULL;
1351 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 0), data);
1353 this_may_throw = data->may_throw;
1354 data->may_throw = save_may_throw;
1356 /* If the body cannot throw, then we can drop the entire TRY_CATCH_EXPR. */
1357 if (!this_may_throw)
1359 if (warn_notreached)
1360 remove_useless_stmts_warn_notreached (TREE_OPERAND (*stmt_p, 1));
1361 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1362 data->repeat = true;
1366 /* Process the catch clause specially. We may be able to tell that
1367 no exceptions propagate past this point. */
1369 this_may_throw = true;
1370 i = tsi_start (TREE_OPERAND (*stmt_p, 1));
1371 stmt = tsi_stmt (i);
1372 data->last_goto = NULL;
1374 switch (TREE_CODE (stmt))
1377 for (; !tsi_end_p (i); tsi_next (&i))
1379 stmt = tsi_stmt (i);
1380 /* If we catch all exceptions, then the body does not
1381 propagate exceptions past this point. */
1382 if (CATCH_TYPES (stmt) == NULL)
1383 this_may_throw = false;
1384 data->last_goto = NULL;
1385 remove_useless_stmts_1 (&CATCH_BODY (stmt), data);
1389 case EH_FILTER_EXPR:
1390 if (EH_FILTER_MUST_NOT_THROW (stmt))
1391 this_may_throw = false;
1392 else if (EH_FILTER_TYPES (stmt) == NULL)
1393 this_may_throw = false;
1394 remove_useless_stmts_1 (&EH_FILTER_FAILURE (stmt), data);
1398 /* Otherwise this is a cleanup. */
1399 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 1), data);
1401 /* If the cleanup is empty, then we can emit the TRY block without
1402 the enclosing TRY_CATCH_EXPR. */
1403 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 1)))
1405 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1406 data->repeat = true;
1410 data->may_throw |= this_may_throw;
1415 remove_useless_stmts_bind (tree *stmt_p, struct rus_data *data)
1419 /* First remove anything underneath the BIND_EXPR. */
1420 remove_useless_stmts_1 (&BIND_EXPR_BODY (*stmt_p), data);
1422 /* If the BIND_EXPR has no variables, then we can pull everything
1423 up one level and remove the BIND_EXPR, unless this is the toplevel
1424 BIND_EXPR for the current function or an inlined function.
1426 When this situation occurs we will want to apply this
1427 optimization again. */
1428 block = BIND_EXPR_BLOCK (*stmt_p);
1429 if (BIND_EXPR_VARS (*stmt_p) == NULL_TREE
1430 && *stmt_p != DECL_SAVED_TREE (current_function_decl)
1432 || ! BLOCK_ABSTRACT_ORIGIN (block)
1433 || (TREE_CODE (BLOCK_ABSTRACT_ORIGIN (block))
1436 *stmt_p = BIND_EXPR_BODY (*stmt_p);
1437 data->repeat = true;
1443 remove_useless_stmts_goto (tree *stmt_p, struct rus_data *data)
1445 tree dest = GOTO_DESTINATION (*stmt_p);
1447 data->may_branch = true;
1448 data->last_goto = NULL;
1450 /* Record the last goto expr, so that we can delete it if unnecessary. */
1451 if (TREE_CODE (dest) == LABEL_DECL)
1452 data->last_goto = stmt_p;
1457 remove_useless_stmts_label (tree *stmt_p, struct rus_data *data)
1459 tree label = LABEL_EXPR_LABEL (*stmt_p);
1461 data->has_label = true;
1463 /* We do want to jump across non-local label receiver code. */
1464 if (DECL_NONLOCAL (label))
1465 data->last_goto = NULL;
1467 else if (data->last_goto && GOTO_DESTINATION (*data->last_goto) == label)
1469 *data->last_goto = build_empty_stmt ();
1470 data->repeat = true;
1473 /* ??? Add something here to delete unused labels. */
1477 /* If the function is "const" or "pure", then clear TREE_SIDE_EFFECTS on its
1478 decl. This allows us to eliminate redundant or useless
1479 calls to "const" functions.
1481 Gimplifier already does the same operation, but we may notice functions
1482 being const and pure once their calls has been gimplified, so we need
1483 to update the flag. */
1486 update_call_expr_flags (tree call)
1488 tree decl = get_callee_fndecl (call);
1491 if (call_expr_flags (call) & (ECF_CONST | ECF_PURE))
1492 TREE_SIDE_EFFECTS (call) = 0;
1493 if (TREE_NOTHROW (decl))
1494 TREE_NOTHROW (call) = 1;
1498 /* T is CALL_EXPR. Set current_function_calls_* flags. */
1501 notice_special_calls (tree t)
1503 int flags = call_expr_flags (t);
1505 if (flags & ECF_MAY_BE_ALLOCA)
1506 current_function_calls_alloca = true;
1507 if (flags & ECF_RETURNS_TWICE)
1508 current_function_calls_setjmp = true;
1512 /* Clear flags set by notice_special_calls. Used by dead code removal
1513 to update the flags. */
1516 clear_special_calls (void)
1518 current_function_calls_alloca = false;
1519 current_function_calls_setjmp = false;
1524 remove_useless_stmts_1 (tree *tp, struct rus_data *data)
1528 switch (TREE_CODE (t))
1531 remove_useless_stmts_cond (tp, data);
1534 case TRY_FINALLY_EXPR:
1535 remove_useless_stmts_tf (tp, data);
1538 case TRY_CATCH_EXPR:
1539 remove_useless_stmts_tc (tp, data);
1543 remove_useless_stmts_bind (tp, data);
1547 remove_useless_stmts_goto (tp, data);
1551 remove_useless_stmts_label (tp, data);
1556 data->last_goto = NULL;
1557 data->may_branch = true;
1562 data->last_goto = NULL;
1563 notice_special_calls (t);
1564 update_call_expr_flags (t);
1565 if (tree_could_throw_p (t))
1566 data->may_throw = true;
1570 data->last_goto = NULL;
1572 op = get_call_expr_in (t);
1575 update_call_expr_flags (op);
1576 notice_special_calls (op);
1578 if (tree_could_throw_p (t))
1579 data->may_throw = true;
1582 case STATEMENT_LIST:
1584 tree_stmt_iterator i = tsi_start (t);
1585 while (!tsi_end_p (i))
1588 if (IS_EMPTY_STMT (t))
1594 remove_useless_stmts_1 (tsi_stmt_ptr (i), data);
1597 if (TREE_CODE (t) == STATEMENT_LIST)
1599 tsi_link_before (&i, t, TSI_SAME_STMT);
1609 data->last_goto = NULL;
1613 data->last_goto = NULL;
1619 remove_useless_stmts (void)
1621 struct rus_data data;
1623 clear_special_calls ();
1627 memset (&data, 0, sizeof (data));
1628 remove_useless_stmts_1 (&DECL_SAVED_TREE (current_function_decl), &data);
1630 while (data.repeat);
1634 struct tree_opt_pass pass_remove_useless_stmts =
1636 "useless", /* name */
1638 remove_useless_stmts, /* execute */
1641 0, /* static_pass_number */
1643 PROP_gimple_any, /* properties_required */
1644 0, /* properties_provided */
1645 0, /* properties_destroyed */
1646 0, /* todo_flags_start */
1647 TODO_dump_func, /* todo_flags_finish */
1652 /* Remove obviously useless statements in basic block BB. */
1655 cfg_remove_useless_stmts_bb (basic_block bb)
1657 block_stmt_iterator bsi;
1658 tree stmt = NULL_TREE;
1659 tree cond, var = NULL_TREE, val = NULL_TREE;
1660 struct var_ann_d *ann;
1662 /* Check whether we come here from a condition, and if so, get the
1664 if (EDGE_COUNT (bb->preds) != 1
1665 || !(EDGE_PRED (bb, 0)->flags & (EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
1668 cond = COND_EXPR_COND (last_stmt (EDGE_PRED (bb, 0)->src));
1670 if (TREE_CODE (cond) == VAR_DECL || TREE_CODE (cond) == PARM_DECL)
1673 val = (EDGE_PRED (bb, 0)->flags & EDGE_FALSE_VALUE
1674 ? boolean_false_node : boolean_true_node);
1676 else if (TREE_CODE (cond) == TRUTH_NOT_EXPR
1677 && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL
1678 || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL))
1680 var = TREE_OPERAND (cond, 0);
1681 val = (EDGE_PRED (bb, 0)->flags & EDGE_FALSE_VALUE
1682 ? boolean_true_node : boolean_false_node);
1686 if (EDGE_PRED (bb, 0)->flags & EDGE_FALSE_VALUE)
1687 cond = invert_truthvalue (cond);
1688 if (TREE_CODE (cond) == EQ_EXPR
1689 && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL
1690 || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL)
1691 && (TREE_CODE (TREE_OPERAND (cond, 1)) == VAR_DECL
1692 || TREE_CODE (TREE_OPERAND (cond, 1)) == PARM_DECL
1693 || TREE_CONSTANT (TREE_OPERAND (cond, 1))))
1695 var = TREE_OPERAND (cond, 0);
1696 val = TREE_OPERAND (cond, 1);
1702 /* Only work for normal local variables. */
1703 ann = var_ann (var);
1706 || TREE_ADDRESSABLE (var))
1709 if (! TREE_CONSTANT (val))
1711 ann = var_ann (val);
1714 || TREE_ADDRESSABLE (val))
1718 /* Ignore floating point variables, since comparison behaves weird for
1720 if (FLOAT_TYPE_P (TREE_TYPE (var)))
1723 for (bsi = bsi_start (bb); !bsi_end_p (bsi);)
1725 stmt = bsi_stmt (bsi);
1727 /* If the THEN/ELSE clause merely assigns a value to a variable/parameter
1728 which is already known to contain that value, then remove the useless
1729 THEN/ELSE clause. */
1730 if (TREE_CODE (stmt) == MODIFY_EXPR
1731 && TREE_OPERAND (stmt, 0) == var
1732 && operand_equal_p (val, TREE_OPERAND (stmt, 1), 0))
1738 /* Invalidate the var if we encounter something that could modify it.
1739 Likewise for the value it was previously set to. Note that we only
1740 consider values that are either a VAR_DECL or PARM_DECL so we
1741 can test for conflict very simply. */
1742 if (TREE_CODE (stmt) == ASM_EXPR
1743 || (TREE_CODE (stmt) == MODIFY_EXPR
1744 && (TREE_OPERAND (stmt, 0) == var
1745 || TREE_OPERAND (stmt, 0) == val)))
1753 /* A CFG-aware version of remove_useless_stmts. */
1756 cfg_remove_useless_stmts (void)
1760 #ifdef ENABLE_CHECKING
1761 verify_flow_info ();
1766 cfg_remove_useless_stmts_bb (bb);
1771 /* Remove PHI nodes associated with basic block BB and all edges out of BB. */
1774 remove_phi_nodes_and_edges_for_unreachable_block (basic_block bb)
1778 /* Since this block is no longer reachable, we can just delete all
1779 of its PHI nodes. */
1780 phi = phi_nodes (bb);
1783 tree next = PHI_CHAIN (phi);
1784 remove_phi_node (phi, NULL_TREE, bb);
1788 /* Remove edges to BB's successors. */
1789 while (EDGE_COUNT (bb->succs) > 0)
1790 ssa_remove_edge (EDGE_SUCC (bb, 0));
1794 /* Remove statements of basic block BB. */
1797 remove_bb (basic_block bb)
1799 block_stmt_iterator i;
1800 source_locus loc = 0;
1804 fprintf (dump_file, "Removing basic block %d\n", bb->index);
1805 if (dump_flags & TDF_DETAILS)
1807 dump_bb (bb, dump_file, 0);
1808 fprintf (dump_file, "\n");
1812 /* Remove all the instructions in the block. */
1813 for (i = bsi_start (bb); !bsi_end_p (i); bsi_remove (&i))
1815 tree stmt = bsi_stmt (i);
1816 release_defs (stmt);
1818 set_bb_for_stmt (stmt, NULL);
1820 /* Don't warn for removed gotos. Gotos are often removed due to
1821 jump threading, thus resulting in bogus warnings. Not great,
1822 since this way we lose warnings for gotos in the original
1823 program that are indeed unreachable. */
1824 if (TREE_CODE (stmt) != GOTO_EXPR && EXPR_HAS_LOCATION (stmt) && !loc)
1825 #ifdef USE_MAPPED_LOCATION
1826 loc = EXPR_LOCATION (stmt);
1828 loc = EXPR_LOCUS (stmt);
1832 /* If requested, give a warning that the first statement in the
1833 block is unreachable. We walk statements backwards in the
1834 loop above, so the last statement we process is the first statement
1836 if (warn_notreached && loc)
1837 #ifdef USE_MAPPED_LOCATION
1838 warning ("%Hwill never be executed", &loc);
1840 warning ("%Hwill never be executed", loc);
1843 remove_phi_nodes_and_edges_for_unreachable_block (bb);
1847 /* Examine BB to determine if it is a forwarding block (a block which only
1848 transfers control to a new destination). If BB is a forwarding block,
1849 then return the edge leading to the ultimate destination. */
1852 tree_block_forwards_to (basic_block bb)
1854 block_stmt_iterator bsi;
1855 bb_ann_t ann = bb_ann (bb);
1858 /* If this block is not forwardable, then avoid useless work. */
1859 if (! ann->forwardable)
1862 /* Set this block to not be forwardable. This prevents infinite loops since
1863 any block currently under examination is considered non-forwardable. */
1864 ann->forwardable = 0;
1866 /* No forwarding is possible if this block is a special block (ENTRY/EXIT),
1867 this block has more than one successor, this block's single successor is
1868 reached via an abnormal edge, this block has phi nodes, or this block's
1869 single successor has phi nodes. */
1870 if (bb == EXIT_BLOCK_PTR
1871 || bb == ENTRY_BLOCK_PTR
1872 || EDGE_COUNT (bb->succs) != 1
1873 || EDGE_SUCC (bb, 0)->dest == EXIT_BLOCK_PTR
1874 || (EDGE_SUCC (bb, 0)->flags & EDGE_ABNORMAL) != 0
1876 || phi_nodes (EDGE_SUCC (bb, 0)->dest))
1879 /* Walk past any labels at the start of this block. */
1880 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
1882 stmt = bsi_stmt (bsi);
1883 if (TREE_CODE (stmt) != LABEL_EXPR)
1887 /* If we reached the end of this block we may be able to optimize this
1889 if (bsi_end_p (bsi))
1893 /* Recursive call to pick up chains of forwarding blocks. */
1894 dest = tree_block_forwards_to (EDGE_SUCC (bb, 0)->dest);
1896 /* If none found, we forward to bb->succs[0] at minimum. */
1898 dest = EDGE_SUCC (bb, 0);
1900 ann->forwardable = 1;
1904 /* No forwarding possible. */
1909 /* Try to remove superfluous control structures. */
1912 cleanup_control_flow (void)
1915 block_stmt_iterator bsi;
1916 bool retval = false;
1921 bsi = bsi_last (bb);
1923 if (bsi_end_p (bsi))
1926 stmt = bsi_stmt (bsi);
1927 if (TREE_CODE (stmt) == COND_EXPR
1928 || TREE_CODE (stmt) == SWITCH_EXPR)
1929 retval |= cleanup_control_expr_graph (bb, bsi);
1935 /* Disconnect an unreachable block in the control expression starting
1939 cleanup_control_expr_graph (basic_block bb, block_stmt_iterator bsi)
1942 bool retval = false;
1943 tree expr = bsi_stmt (bsi), val;
1945 if (EDGE_COUNT (bb->succs) > 1)
1950 switch (TREE_CODE (expr))
1953 val = COND_EXPR_COND (expr);
1957 val = SWITCH_COND (expr);
1958 if (TREE_CODE (val) != INTEGER_CST)
1966 taken_edge = find_taken_edge (bb, val);
1970 /* Remove all the edges except the one that is always executed. */
1971 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
1973 if (e != taken_edge)
1975 taken_edge->probability += e->probability;
1976 taken_edge->count += e->count;
1977 ssa_remove_edge (e);
1983 if (taken_edge->probability > REG_BR_PROB_BASE)
1984 taken_edge->probability = REG_BR_PROB_BASE;
1987 taken_edge = EDGE_SUCC (bb, 0);
1990 taken_edge->flags = EDGE_FALLTHRU;
1992 /* We removed some paths from the cfg. */
1993 if (dom_computed[CDI_DOMINATORS] >= DOM_CONS_OK)
1994 dom_computed[CDI_DOMINATORS] = DOM_CONS_OK;
2000 /* Given a control block BB and a predicate VAL, return the edge that
2001 will be taken out of the block. If VAL does not match a unique
2002 edge, NULL is returned. */
2005 find_taken_edge (basic_block bb, tree val)
2009 stmt = last_stmt (bb);
2012 gcc_assert (is_ctrl_stmt (stmt));
2014 /* If VAL is a predicate of the form N RELOP N, where N is an
2015 SSA_NAME, we can usually determine its truth value. */
2016 if (val && COMPARISON_CLASS_P (val))
2019 /* If VAL is not a constant, we can't determine which edge might
2021 if (val == NULL || !really_constant_p (val))
2024 if (TREE_CODE (stmt) == COND_EXPR)
2025 return find_taken_edge_cond_expr (bb, val);
2027 if (TREE_CODE (stmt) == SWITCH_EXPR)
2028 return find_taken_edge_switch_expr (bb, val);
2030 return EDGE_SUCC (bb, 0);
2034 /* Given a constant value VAL and the entry block BB to a COND_EXPR
2035 statement, determine which of the two edges will be taken out of the
2036 block. Return NULL if either edge may be taken. */
2039 find_taken_edge_cond_expr (basic_block bb, tree val)
2041 edge true_edge, false_edge;
2043 extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
2045 /* If both edges of the branch lead to the same basic block, it doesn't
2046 matter which edge is taken. */
2047 if (true_edge->dest == false_edge->dest)
2050 /* Otherwise, try to determine which branch of the if() will be taken.
2051 If VAL is a constant but it can't be reduced to a 0 or a 1, then
2052 we don't really know which edge will be taken at runtime. This
2053 may happen when comparing addresses (e.g., if (&var1 == 4)). */
2054 if (integer_nonzerop (val))
2056 else if (integer_zerop (val))
2063 /* Given a constant value VAL and the entry block BB to a SWITCH_EXPR
2064 statement, determine which edge will be taken out of the block. Return
2065 NULL if any edge may be taken. */
2068 find_taken_edge_switch_expr (basic_block bb, tree val)
2070 tree switch_expr, taken_case;
2071 basic_block dest_bb;
2074 if (TREE_CODE (val) != INTEGER_CST)
2077 switch_expr = last_stmt (bb);
2078 taken_case = find_case_label_for_value (switch_expr, val);
2079 dest_bb = label_to_block (CASE_LABEL (taken_case));
2081 e = find_edge (bb, dest_bb);
2087 /* Return the CASE_LABEL_EXPR that SWITCH_EXPR will take for VAL.
2088 We can make optimal use here of the fact that the case labels are
2089 sorted: We can do a binary search for a case matching VAL. */
2092 find_case_label_for_value (tree switch_expr, tree val)
2094 tree vec = SWITCH_LABELS (switch_expr);
2095 size_t low, high, n = TREE_VEC_LENGTH (vec);
2096 tree default_case = TREE_VEC_ELT (vec, n - 1);
2098 for (low = -1, high = n - 1; high - low > 1; )
2100 size_t i = (high + low) / 2;
2101 tree t = TREE_VEC_ELT (vec, i);
2104 /* Cache the result of comparing CASE_LOW and val. */
2105 cmp = tree_int_cst_compare (CASE_LOW (t), val);
2112 if (CASE_HIGH (t) == NULL)
2114 /* A singe-valued case label. */
2120 /* A case range. We can only handle integer ranges. */
2121 if (cmp <= 0 && tree_int_cst_compare (CASE_HIGH (t), val) >= 0)
2126 return default_case;
2130 /* If all the PHI nodes in DEST have alternatives for E1 and E2 and
2131 those alternatives are equal in each of the PHI nodes, then return
2132 true, else return false. */
2135 phi_alternatives_equal (basic_block dest, edge e1, edge e2)
2137 tree phi, val1, val2;
2140 for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi))
2142 n1 = phi_arg_from_edge (phi, e1);
2143 n2 = phi_arg_from_edge (phi, e2);
2145 gcc_assert (n1 >= 0);
2146 gcc_assert (n2 >= 0);
2148 val1 = PHI_ARG_DEF (phi, n1);
2149 val2 = PHI_ARG_DEF (phi, n2);
2151 if (!operand_equal_p (val1, val2, 0))
2159 /*---------------------------------------------------------------------------
2161 ---------------------------------------------------------------------------*/
2163 /* Dump tree-specific information of block BB to file OUTF. */
2166 tree_dump_bb (basic_block bb, FILE *outf, int indent)
2168 dump_generic_bb (outf, bb, indent, TDF_VOPS);
2172 /* Dump a basic block on stderr. */
2175 debug_tree_bb (basic_block bb)
2177 dump_bb (bb, stderr, 0);
2181 /* Dump basic block with index N on stderr. */
2184 debug_tree_bb_n (int n)
2186 debug_tree_bb (BASIC_BLOCK (n));
2187 return BASIC_BLOCK (n);
2191 /* Dump the CFG on stderr.
2193 FLAGS are the same used by the tree dumping functions
2194 (see TDF_* in tree.h). */
2197 debug_tree_cfg (int flags)
2199 dump_tree_cfg (stderr, flags);
2203 /* Dump the program showing basic block boundaries on the given FILE.
2205 FLAGS are the same used by the tree dumping functions (see TDF_* in
2209 dump_tree_cfg (FILE *file, int flags)
2211 if (flags & TDF_DETAILS)
2213 const char *funcname
2214 = lang_hooks.decl_printable_name (current_function_decl, 2);
2217 fprintf (file, ";; Function %s\n\n", funcname);
2218 fprintf (file, ";; \n%d basic blocks, %d edges, last basic block %d.\n\n",
2219 n_basic_blocks, n_edges, last_basic_block);
2221 brief_dump_cfg (file);
2222 fprintf (file, "\n");
2225 if (flags & TDF_STATS)
2226 dump_cfg_stats (file);
2228 dump_function_to_file (current_function_decl, file, flags | TDF_BLOCKS);
2232 /* Dump CFG statistics on FILE. */
2235 dump_cfg_stats (FILE *file)
2237 static long max_num_merged_labels = 0;
2238 unsigned long size, total = 0;
2241 const char * const fmt_str = "%-30s%-13s%12s\n";
2242 const char * const fmt_str_1 = "%-30s%13d%11lu%c\n";
2243 const char * const fmt_str_3 = "%-43s%11lu%c\n";
2244 const char *funcname
2245 = lang_hooks.decl_printable_name (current_function_decl, 2);
2248 fprintf (file, "\nCFG Statistics for %s\n\n", funcname);
2250 fprintf (file, "---------------------------------------------------------\n");
2251 fprintf (file, fmt_str, "", " Number of ", "Memory");
2252 fprintf (file, fmt_str, "", " instances ", "used ");
2253 fprintf (file, "---------------------------------------------------------\n");
2255 size = n_basic_blocks * sizeof (struct basic_block_def);
2257 fprintf (file, fmt_str_1, "Basic blocks", n_basic_blocks,
2258 SCALE (size), LABEL (size));
2262 n_edges += EDGE_COUNT (bb->succs);
2263 size = n_edges * sizeof (struct edge_def);
2265 fprintf (file, fmt_str_1, "Edges", n_edges, SCALE (size), LABEL (size));
2267 size = n_basic_blocks * sizeof (struct bb_ann_d);
2269 fprintf (file, fmt_str_1, "Basic block annotations", n_basic_blocks,
2270 SCALE (size), LABEL (size));
2272 fprintf (file, "---------------------------------------------------------\n");
2273 fprintf (file, fmt_str_3, "Total memory used by CFG data", SCALE (total),
2275 fprintf (file, "---------------------------------------------------------\n");
2276 fprintf (file, "\n");
2278 if (cfg_stats.num_merged_labels > max_num_merged_labels)
2279 max_num_merged_labels = cfg_stats.num_merged_labels;
2281 fprintf (file, "Coalesced label blocks: %ld (Max so far: %ld)\n",
2282 cfg_stats.num_merged_labels, max_num_merged_labels);
2284 fprintf (file, "\n");
2288 /* Dump CFG statistics on stderr. Keep extern so that it's always
2289 linked in the final executable. */
2292 debug_cfg_stats (void)
2294 dump_cfg_stats (stderr);
2298 /* Dump the flowgraph to a .vcg FILE. */
2301 tree_cfg2vcg (FILE *file)
2306 const char *funcname
2307 = lang_hooks.decl_printable_name (current_function_decl, 2);
2309 /* Write the file header. */
2310 fprintf (file, "graph: { title: \"%s\"\n", funcname);
2311 fprintf (file, "node: { title: \"ENTRY\" label: \"ENTRY\" }\n");
2312 fprintf (file, "node: { title: \"EXIT\" label: \"EXIT\" }\n");
2314 /* Write blocks and edges. */
2315 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
2317 fprintf (file, "edge: { sourcename: \"ENTRY\" targetname: \"%d\"",
2320 if (e->flags & EDGE_FAKE)
2321 fprintf (file, " linestyle: dotted priority: 10");
2323 fprintf (file, " linestyle: solid priority: 100");
2325 fprintf (file, " }\n");
2331 enum tree_code head_code, end_code;
2332 const char *head_name, *end_name;
2335 tree first = first_stmt (bb);
2336 tree last = last_stmt (bb);
2340 head_code = TREE_CODE (first);
2341 head_name = tree_code_name[head_code];
2342 head_line = get_lineno (first);
2345 head_name = "no-statement";
2349 end_code = TREE_CODE (last);
2350 end_name = tree_code_name[end_code];
2351 end_line = get_lineno (last);
2354 end_name = "no-statement";
2356 fprintf (file, "node: { title: \"%d\" label: \"#%d\\n%s (%d)\\n%s (%d)\"}\n",
2357 bb->index, bb->index, head_name, head_line, end_name,
2360 FOR_EACH_EDGE (e, ei, bb->succs)
2362 if (e->dest == EXIT_BLOCK_PTR)
2363 fprintf (file, "edge: { sourcename: \"%d\" targetname: \"EXIT\"", bb->index);
2365 fprintf (file, "edge: { sourcename: \"%d\" targetname: \"%d\"", bb->index, e->dest->index);
2367 if (e->flags & EDGE_FAKE)
2368 fprintf (file, " priority: 10 linestyle: dotted");
2370 fprintf (file, " priority: 100 linestyle: solid");
2372 fprintf (file, " }\n");
2375 if (bb->next_bb != EXIT_BLOCK_PTR)
2379 fputs ("}\n\n", file);
2384 /*---------------------------------------------------------------------------
2385 Miscellaneous helpers
2386 ---------------------------------------------------------------------------*/
2388 /* Return true if T represents a stmt that always transfers control. */
2391 is_ctrl_stmt (tree t)
2393 return (TREE_CODE (t) == COND_EXPR
2394 || TREE_CODE (t) == SWITCH_EXPR
2395 || TREE_CODE (t) == GOTO_EXPR
2396 || TREE_CODE (t) == RETURN_EXPR
2397 || TREE_CODE (t) == RESX_EXPR);
2401 /* Return true if T is a statement that may alter the flow of control
2402 (e.g., a call to a non-returning function). */
2405 is_ctrl_altering_stmt (tree t)
2410 call = get_call_expr_in (t);
2413 /* A non-pure/const CALL_EXPR alters flow control if the current
2414 function has nonlocal labels. */
2415 if (TREE_SIDE_EFFECTS (call) && current_function_has_nonlocal_label)
2418 /* A CALL_EXPR also alters control flow if it does not return. */
2419 if (call_expr_flags (call) & (ECF_NORETURN | ECF_LONGJMP))
2423 /* If a statement can throw, it alters control flow. */
2424 return tree_can_throw_internal (t);
2428 /* Return true if T is a computed goto. */
2431 computed_goto_p (tree t)
2433 return (TREE_CODE (t) == GOTO_EXPR
2434 && TREE_CODE (GOTO_DESTINATION (t)) != LABEL_DECL);
2438 /* Checks whether EXPR is a simple local goto. */
2441 simple_goto_p (tree expr)
2443 return (TREE_CODE (expr) == GOTO_EXPR
2444 && TREE_CODE (GOTO_DESTINATION (expr)) == LABEL_DECL);
2448 /* Return true if T should start a new basic block. PREV_T is the
2449 statement preceding T. It is used when T is a label or a case label.
2450 Labels should only start a new basic block if their previous statement
2451 wasn't a label. Otherwise, sequence of labels would generate
2452 unnecessary basic blocks that only contain a single label. */
2455 stmt_starts_bb_p (tree t, tree prev_t)
2457 enum tree_code code;
2462 /* LABEL_EXPRs start a new basic block only if the preceding
2463 statement wasn't a label of the same type. This prevents the
2464 creation of consecutive blocks that have nothing but a single
2466 code = TREE_CODE (t);
2467 if (code == LABEL_EXPR)
2469 /* Nonlocal and computed GOTO targets always start a new block. */
2470 if (code == LABEL_EXPR
2471 && (DECL_NONLOCAL (LABEL_EXPR_LABEL (t))
2472 || FORCED_LABEL (LABEL_EXPR_LABEL (t))))
2475 if (prev_t && TREE_CODE (prev_t) == code)
2477 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (prev_t)))
2480 cfg_stats.num_merged_labels++;
2491 /* Return true if T should end a basic block. */
2494 stmt_ends_bb_p (tree t)
2496 return is_ctrl_stmt (t) || is_ctrl_altering_stmt (t);
2500 /* Add gotos that used to be represented implicitly in the CFG. */
2503 disband_implicit_edges (void)
2506 block_stmt_iterator last;
2513 last = bsi_last (bb);
2514 stmt = last_stmt (bb);
2516 if (stmt && TREE_CODE (stmt) == COND_EXPR)
2518 /* Remove superfluous gotos from COND_EXPR branches. Moved
2519 from cfg_remove_useless_stmts here since it violates the
2520 invariants for tree--cfg correspondence and thus fits better
2521 here where we do it anyway. */
2522 FOR_EACH_EDGE (e, ei, bb->succs)
2524 if (e->dest != bb->next_bb)
2527 if (e->flags & EDGE_TRUE_VALUE)
2528 COND_EXPR_THEN (stmt) = build_empty_stmt ();
2529 else if (e->flags & EDGE_FALSE_VALUE)
2530 COND_EXPR_ELSE (stmt) = build_empty_stmt ();
2533 e->flags |= EDGE_FALLTHRU;
2539 if (stmt && TREE_CODE (stmt) == RETURN_EXPR)
2541 /* Remove the RETURN_EXPR if we may fall though to the exit
2543 gcc_assert (EDGE_COUNT (bb->succs) == 1);
2544 gcc_assert (EDGE_SUCC (bb, 0)->dest == EXIT_BLOCK_PTR);
2546 if (bb->next_bb == EXIT_BLOCK_PTR
2547 && !TREE_OPERAND (stmt, 0))
2550 EDGE_SUCC (bb, 0)->flags |= EDGE_FALLTHRU;
2555 /* There can be no fallthru edge if the last statement is a control
2557 if (stmt && is_ctrl_stmt (stmt))
2560 /* Find a fallthru edge and emit the goto if necessary. */
2561 FOR_EACH_EDGE (e, ei, bb->succs)
2562 if (e->flags & EDGE_FALLTHRU)
2565 if (!e || e->dest == bb->next_bb)
2568 gcc_assert (e->dest != EXIT_BLOCK_PTR);
2569 label = tree_block_label (e->dest);
2571 stmt = build1 (GOTO_EXPR, void_type_node, label);
2572 #ifdef USE_MAPPED_LOCATION
2573 SET_EXPR_LOCATION (stmt, e->goto_locus);
2575 SET_EXPR_LOCUS (stmt, e->goto_locus);
2577 bsi_insert_after (&last, stmt, BSI_NEW_STMT);
2578 e->flags &= ~EDGE_FALLTHRU;
2582 /* Remove block annotations and other datastructures. */
2585 delete_tree_cfg_annotations (void)
2588 if (n_basic_blocks > 0)
2589 free_blocks_annotations ();
2591 label_to_block_map = NULL;
2598 /* Return the first statement in basic block BB. */
2601 first_stmt (basic_block bb)
2603 block_stmt_iterator i = bsi_start (bb);
2604 return !bsi_end_p (i) ? bsi_stmt (i) : NULL_TREE;
2608 /* Return the last statement in basic block BB. */
2611 last_stmt (basic_block bb)
2613 block_stmt_iterator b = bsi_last (bb);
2614 return !bsi_end_p (b) ? bsi_stmt (b) : NULL_TREE;
2618 /* Return a pointer to the last statement in block BB. */
2621 last_stmt_ptr (basic_block bb)
2623 block_stmt_iterator last = bsi_last (bb);
2624 return !bsi_end_p (last) ? bsi_stmt_ptr (last) : NULL;
2628 /* Return the last statement of an otherwise empty block. Return NULL
2629 if the block is totally empty, or if it contains more than one
2633 last_and_only_stmt (basic_block bb)
2635 block_stmt_iterator i = bsi_last (bb);
2641 last = bsi_stmt (i);
2646 /* Empty statements should no longer appear in the instruction stream.
2647 Everything that might have appeared before should be deleted by
2648 remove_useless_stmts, and the optimizers should just bsi_remove
2649 instead of smashing with build_empty_stmt.
2651 Thus the only thing that should appear here in a block containing
2652 one executable statement is a label. */
2653 prev = bsi_stmt (i);
2654 if (TREE_CODE (prev) == LABEL_EXPR)
2661 /* Mark BB as the basic block holding statement T. */
2664 set_bb_for_stmt (tree t, basic_block bb)
2666 if (TREE_CODE (t) == PHI_NODE)
2668 else if (TREE_CODE (t) == STATEMENT_LIST)
2670 tree_stmt_iterator i;
2671 for (i = tsi_start (t); !tsi_end_p (i); tsi_next (&i))
2672 set_bb_for_stmt (tsi_stmt (i), bb);
2676 stmt_ann_t ann = get_stmt_ann (t);
2679 /* If the statement is a label, add the label to block-to-labels map
2680 so that we can speed up edge creation for GOTO_EXPRs. */
2681 if (TREE_CODE (t) == LABEL_EXPR)
2685 t = LABEL_EXPR_LABEL (t);
2686 uid = LABEL_DECL_UID (t);
2689 LABEL_DECL_UID (t) = uid = cfun->last_label_uid++;
2690 if (VARRAY_SIZE (label_to_block_map) <= (unsigned) uid)
2691 VARRAY_GROW (label_to_block_map, 3 * uid / 2);
2694 /* We're moving an existing label. Make sure that we've
2695 removed it from the old block. */
2696 gcc_assert (!bb || !VARRAY_BB (label_to_block_map, uid));
2697 VARRAY_BB (label_to_block_map, uid) = bb;
2702 /* Finds iterator for STMT. */
2704 extern block_stmt_iterator
2705 stmt_for_bsi (tree stmt)
2707 block_stmt_iterator bsi;
2709 for (bsi = bsi_start (bb_for_stmt (stmt)); !bsi_end_p (bsi); bsi_next (&bsi))
2710 if (bsi_stmt (bsi) == stmt)
2716 /* Insert statement (or statement list) T before the statement
2717 pointed-to by iterator I. M specifies how to update iterator I
2718 after insertion (see enum bsi_iterator_update). */
2721 bsi_insert_before (block_stmt_iterator *i, tree t, enum bsi_iterator_update m)
2723 set_bb_for_stmt (t, i->bb);
2724 tsi_link_before (&i->tsi, t, m);
2729 /* Insert statement (or statement list) T after the statement
2730 pointed-to by iterator I. M specifies how to update iterator I
2731 after insertion (see enum bsi_iterator_update). */
2734 bsi_insert_after (block_stmt_iterator *i, tree t, enum bsi_iterator_update m)
2736 set_bb_for_stmt (t, i->bb);
2737 tsi_link_after (&i->tsi, t, m);
2742 /* Remove the statement pointed to by iterator I. The iterator is updated
2743 to the next statement. */
2746 bsi_remove (block_stmt_iterator *i)
2748 tree t = bsi_stmt (*i);
2749 set_bb_for_stmt (t, NULL);
2750 tsi_delink (&i->tsi);
2754 /* Move the statement at FROM so it comes right after the statement at TO. */
2757 bsi_move_after (block_stmt_iterator *from, block_stmt_iterator *to)
2759 tree stmt = bsi_stmt (*from);
2761 bsi_insert_after (to, stmt, BSI_SAME_STMT);
2765 /* Move the statement at FROM so it comes right before the statement at TO. */
2768 bsi_move_before (block_stmt_iterator *from, block_stmt_iterator *to)
2770 tree stmt = bsi_stmt (*from);
2772 bsi_insert_before (to, stmt, BSI_SAME_STMT);
2776 /* Move the statement at FROM to the end of basic block BB. */
2779 bsi_move_to_bb_end (block_stmt_iterator *from, basic_block bb)
2781 block_stmt_iterator last = bsi_last (bb);
2783 /* Have to check bsi_end_p because it could be an empty block. */
2784 if (!bsi_end_p (last) && is_ctrl_stmt (bsi_stmt (last)))
2785 bsi_move_before (from, &last);
2787 bsi_move_after (from, &last);
2791 /* Replace the contents of the statement pointed to by iterator BSI
2792 with STMT. If PRESERVE_EH_INFO is true, the exception handling
2793 information of the original statement is preserved. */
2796 bsi_replace (const block_stmt_iterator *bsi, tree stmt, bool preserve_eh_info)
2799 tree orig_stmt = bsi_stmt (*bsi);
2801 SET_EXPR_LOCUS (stmt, EXPR_LOCUS (orig_stmt));
2802 set_bb_for_stmt (stmt, bsi->bb);
2804 /* Preserve EH region information from the original statement, if
2805 requested by the caller. */
2806 if (preserve_eh_info)
2808 eh_region = lookup_stmt_eh_region (orig_stmt);
2810 add_stmt_to_eh_region (stmt, eh_region);
2813 *bsi_stmt_ptr (*bsi) = stmt;
2818 /* Insert the statement pointed-to by BSI into edge E. Every attempt
2819 is made to place the statement in an existing basic block, but
2820 sometimes that isn't possible. When it isn't possible, the edge is
2821 split and the statement is added to the new block.
2823 In all cases, the returned *BSI points to the correct location. The
2824 return value is true if insertion should be done after the location,
2825 or false if it should be done before the location. If new basic block
2826 has to be created, it is stored in *NEW_BB. */
2829 tree_find_edge_insert_loc (edge e, block_stmt_iterator *bsi,
2830 basic_block *new_bb)
2832 basic_block dest, src;
2838 /* If the destination has one predecessor which has no PHI nodes,
2839 insert there. Except for the exit block.
2841 The requirement for no PHI nodes could be relaxed. Basically we
2842 would have to examine the PHIs to prove that none of them used
2843 the value set by the statement we want to insert on E. That
2844 hardly seems worth the effort. */
2845 if (EDGE_COUNT (dest->preds) == 1
2846 && ! phi_nodes (dest)
2847 && dest != EXIT_BLOCK_PTR)
2849 *bsi = bsi_start (dest);
2850 if (bsi_end_p (*bsi))
2853 /* Make sure we insert after any leading labels. */
2854 tmp = bsi_stmt (*bsi);
2855 while (TREE_CODE (tmp) == LABEL_EXPR)
2858 if (bsi_end_p (*bsi))
2860 tmp = bsi_stmt (*bsi);
2863 if (bsi_end_p (*bsi))
2865 *bsi = bsi_last (dest);
2872 /* If the source has one successor, the edge is not abnormal and
2873 the last statement does not end a basic block, insert there.
2874 Except for the entry block. */
2876 if ((e->flags & EDGE_ABNORMAL) == 0
2877 && EDGE_COUNT (src->succs) == 1
2878 && src != ENTRY_BLOCK_PTR)
2880 *bsi = bsi_last (src);
2881 if (bsi_end_p (*bsi))
2884 tmp = bsi_stmt (*bsi);
2885 if (!stmt_ends_bb_p (tmp))
2888 /* Insert code just before returning the value. We may need to decompose
2889 the return in the case it contains non-trivial operand. */
2890 if (TREE_CODE (tmp) == RETURN_EXPR)
2892 tree op = TREE_OPERAND (tmp, 0);
2893 if (!is_gimple_val (op))
2895 gcc_assert (TREE_CODE (op) == MODIFY_EXPR);
2896 bsi_insert_before (bsi, op, BSI_NEW_STMT);
2897 TREE_OPERAND (tmp, 0) = TREE_OPERAND (op, 0);
2904 /* Otherwise, create a new basic block, and split this edge. */
2905 dest = split_edge (e);
2908 e = EDGE_PRED (dest, 0);
2913 /* This routine will commit all pending edge insertions, creating any new
2914 basic blocks which are necessary.
2916 If specified, NEW_BLOCKS returns a count of the number of new basic
2917 blocks which were created. */
2920 bsi_commit_edge_inserts (int *new_blocks)
2927 blocks = n_basic_blocks;
2929 bsi_commit_edge_inserts_1 (EDGE_SUCC (ENTRY_BLOCK_PTR, 0));
2932 FOR_EACH_EDGE (e, ei, bb->succs)
2933 bsi_commit_edge_inserts_1 (e);
2936 *new_blocks = n_basic_blocks - blocks;
2940 /* Commit insertions pending at edge E. */
2943 bsi_commit_edge_inserts_1 (edge e)
2945 if (PENDING_STMT (e))
2947 block_stmt_iterator bsi;
2948 tree stmt = PENDING_STMT (e);
2950 PENDING_STMT (e) = NULL_TREE;
2952 if (tree_find_edge_insert_loc (e, &bsi, NULL))
2953 bsi_insert_after (&bsi, stmt, BSI_NEW_STMT);
2955 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
2960 /* Add STMT to the pending list of edge E. No actual insertion is
2961 made until a call to bsi_commit_edge_inserts () is made. */
2964 bsi_insert_on_edge (edge e, tree stmt)
2966 append_to_statement_list (stmt, &PENDING_STMT (e));
2969 /* Similar to bsi_insert_on_edge+bsi_commit_edge_inserts. If new block has to
2970 be created, it is returned. */
2973 bsi_insert_on_edge_immediate (edge e, tree stmt)
2975 block_stmt_iterator bsi;
2976 basic_block new_bb = NULL;
2978 gcc_assert (!PENDING_STMT (e));
2980 if (tree_find_edge_insert_loc (e, &bsi, &new_bb))
2981 bsi_insert_after (&bsi, stmt, BSI_NEW_STMT);
2983 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
2988 /*---------------------------------------------------------------------------
2989 Tree specific functions for CFG manipulation
2990 ---------------------------------------------------------------------------*/
2992 /* Split a (typically critical) edge EDGE_IN. Return the new block.
2993 Abort on abnormal edges. */
2996 tree_split_edge (edge edge_in)
2998 basic_block new_bb, after_bb, dest, src;
3004 /* Abnormal edges cannot be split. */
3005 gcc_assert (!(edge_in->flags & EDGE_ABNORMAL));
3008 dest = edge_in->dest;
3010 /* Place the new block in the block list. Try to keep the new block
3011 near its "logical" location. This is of most help to humans looking
3012 at debugging dumps. */
3013 FOR_EACH_EDGE (e, ei, dest->preds)
3014 if (e->src->next_bb == dest)
3017 after_bb = dest->prev_bb;
3019 after_bb = edge_in->src;
3021 new_bb = create_empty_bb (after_bb);
3022 new_bb->frequency = EDGE_FREQUENCY (edge_in);
3023 new_bb->count = edge_in->count;
3024 new_edge = make_edge (new_bb, dest, EDGE_FALLTHRU);
3025 new_edge->probability = REG_BR_PROB_BASE;
3026 new_edge->count = edge_in->count;
3028 /* Find all the PHI arguments on the original edge, and change them to
3029 the new edge. Do it before redirection, so that the argument does not
3031 for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi))
3033 num_elem = PHI_NUM_ARGS (phi);
3034 for (i = 0; i < num_elem; i++)
3035 if (PHI_ARG_EDGE (phi, i) == edge_in)
3037 PHI_ARG_EDGE (phi, i) = new_edge;
3042 e = redirect_edge_and_branch (edge_in, new_bb);
3044 gcc_assert (!PENDING_STMT (edge_in));
3050 /* Return true when BB has label LABEL in it. */
3053 has_label_p (basic_block bb, tree label)
3055 block_stmt_iterator bsi;
3057 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3059 tree stmt = bsi_stmt (bsi);
3061 if (TREE_CODE (stmt) != LABEL_EXPR)
3063 if (LABEL_EXPR_LABEL (stmt) == label)
3070 /* Callback for walk_tree, check that all elements with address taken are
3071 properly noticed as such. */
3074 verify_expr (tree *tp, int *walk_subtrees, void *data ATTRIBUTE_UNUSED)
3081 /* Check operand N for being valid GIMPLE and give error MSG if not.
3082 We check for constants explicitly since they are not considered
3083 gimple invariants if they overflowed. */
3084 #define CHECK_OP(N, MSG) \
3085 do { if (!CONSTANT_CLASS_P (TREE_OPERAND (t, N)) \
3086 && !is_gimple_val (TREE_OPERAND (t, N))) \
3087 { error (MSG); return TREE_OPERAND (t, N); }} while (0)
3089 switch (TREE_CODE (t))
3092 if (SSA_NAME_IN_FREE_LIST (t))
3094 error ("SSA name in freelist but still referenced");
3100 x = TREE_OPERAND (t, 0);
3101 if (TREE_CODE (x) == BIT_FIELD_REF
3102 && is_gimple_reg (TREE_OPERAND (x, 0)))
3104 error ("GIMPLE register modified with BIT_FIELD_REF");
3110 /* Skip any references (they will be checked when we recurse down the
3111 tree) and ensure that any variable used as a prefix is marked
3113 for (x = TREE_OPERAND (t, 0);
3114 (handled_component_p (x)
3115 || TREE_CODE (x) == REALPART_EXPR
3116 || TREE_CODE (x) == IMAGPART_EXPR);
3117 x = TREE_OPERAND (x, 0))
3120 if (TREE_CODE (x) != VAR_DECL && TREE_CODE (x) != PARM_DECL)
3122 if (!TREE_ADDRESSABLE (x))
3124 error ("address taken, but ADDRESSABLE bit not set");
3130 x = TREE_OPERAND (t, 0);
3131 if (TREE_CODE (TREE_TYPE (x)) != BOOLEAN_TYPE)
3133 error ("non-boolean used in condition");
3140 case FIX_TRUNC_EXPR:
3142 case FIX_FLOOR_EXPR:
3143 case FIX_ROUND_EXPR:
3148 case NON_LVALUE_EXPR:
3149 case TRUTH_NOT_EXPR:
3150 CHECK_OP (0, "Invalid operand to unary operator");
3157 case ARRAY_RANGE_REF:
3159 case VIEW_CONVERT_EXPR:
3160 /* We have a nest of references. Verify that each of the operands
3161 that determine where to reference is either a constant or a variable,
3162 verify that the base is valid, and then show we've already checked
3164 while (TREE_CODE (t) == REALPART_EXPR || TREE_CODE (t) == IMAGPART_EXPR
3165 || handled_component_p (t))
3167 if (TREE_CODE (t) == COMPONENT_REF && TREE_OPERAND (t, 2))
3168 CHECK_OP (2, "Invalid COMPONENT_REF offset operator");
3169 else if (TREE_CODE (t) == ARRAY_REF
3170 || TREE_CODE (t) == ARRAY_RANGE_REF)
3172 CHECK_OP (1, "Invalid array index.");
3173 if (TREE_OPERAND (t, 2))
3174 CHECK_OP (2, "Invalid array lower bound.");
3175 if (TREE_OPERAND (t, 3))
3176 CHECK_OP (3, "Invalid array stride.");
3178 else if (TREE_CODE (t) == BIT_FIELD_REF)
3180 CHECK_OP (1, "Invalid operand to BIT_FIELD_REF");
3181 CHECK_OP (2, "Invalid operand to BIT_FIELD_REF");
3184 t = TREE_OPERAND (t, 0);
3187 if (!CONSTANT_CLASS_P (t) && !is_gimple_lvalue (t))
3189 error ("Invalid reference prefix.");
3201 case UNORDERED_EXPR:
3212 case TRUNC_DIV_EXPR:
3214 case FLOOR_DIV_EXPR:
3215 case ROUND_DIV_EXPR:
3216 case TRUNC_MOD_EXPR:
3218 case FLOOR_MOD_EXPR:
3219 case ROUND_MOD_EXPR:
3221 case EXACT_DIV_EXPR:
3231 CHECK_OP (0, "Invalid operand to binary operator");
3232 CHECK_OP (1, "Invalid operand to binary operator");
3244 /* Verify STMT, return true if STMT is not in GIMPLE form.
3245 TODO: Implement type checking. */
3248 verify_stmt (tree stmt, bool last_in_block)
3252 if (!is_gimple_stmt (stmt))
3254 error ("Is not a valid GIMPLE statement.");
3258 addr = walk_tree (&stmt, verify_expr, NULL, NULL);
3261 debug_generic_stmt (addr);
3265 /* If the statement is marked as part of an EH region, then it is
3266 expected that the statement could throw. Verify that when we
3267 have optimizations that simplify statements such that we prove
3268 that they cannot throw, that we update other data structures
3270 if (lookup_stmt_eh_region (stmt) >= 0)
3272 if (!tree_could_throw_p (stmt))
3274 error ("Statement marked for throw, but doesn%'t.");
3277 if (!last_in_block && tree_can_throw_internal (stmt))
3279 error ("Statement marked for throw in middle of block.");
3287 debug_generic_stmt (stmt);
3292 /* Return true when the T can be shared. */
3295 tree_node_can_be_shared (tree t)
3297 if (IS_TYPE_OR_DECL_P (t)
3298 /* We check for constants explicitly since they are not considered
3299 gimple invariants if they overflowed. */
3300 || CONSTANT_CLASS_P (t)
3301 || is_gimple_min_invariant (t)
3302 || TREE_CODE (t) == SSA_NAME)
3305 while (((TREE_CODE (t) == ARRAY_REF || TREE_CODE (t) == ARRAY_RANGE_REF)
3306 /* We check for constants explicitly since they are not considered
3307 gimple invariants if they overflowed. */
3308 && (CONSTANT_CLASS_P (TREE_OPERAND (t, 1))
3309 || is_gimple_min_invariant (TREE_OPERAND (t, 1))))
3310 || (TREE_CODE (t) == COMPONENT_REF
3311 || TREE_CODE (t) == REALPART_EXPR
3312 || TREE_CODE (t) == IMAGPART_EXPR))
3313 t = TREE_OPERAND (t, 0);
3322 /* Called via walk_trees. Verify tree sharing. */
3325 verify_node_sharing (tree * tp, int *walk_subtrees, void *data)
3327 htab_t htab = (htab_t) data;
3330 if (tree_node_can_be_shared (*tp))
3332 *walk_subtrees = false;
3336 slot = htab_find_slot (htab, *tp, INSERT);
3345 /* Verify the GIMPLE statement chain. */
3351 block_stmt_iterator bsi;
3356 timevar_push (TV_TREE_STMT_VERIFY);
3357 htab = htab_create (37, htab_hash_pointer, htab_eq_pointer, NULL);
3364 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
3366 int phi_num_args = PHI_NUM_ARGS (phi);
3368 for (i = 0; i < phi_num_args; i++)
3370 tree t = PHI_ARG_DEF (phi, i);
3373 /* Addressable variables do have SSA_NAMEs but they
3374 are not considered gimple values. */
3375 if (TREE_CODE (t) != SSA_NAME
3376 && TREE_CODE (t) != FUNCTION_DECL
3377 && !is_gimple_val (t))
3379 error ("PHI def is not a GIMPLE value");
3380 debug_generic_stmt (phi);
3381 debug_generic_stmt (t);
3385 addr = walk_tree (&t, verify_expr, NULL, NULL);
3388 debug_generic_stmt (addr);
3392 addr = walk_tree (&t, verify_node_sharing, htab, NULL);
3395 error ("Incorrect sharing of tree nodes");
3396 debug_generic_stmt (phi);
3397 debug_generic_stmt (addr);
3403 for (bsi = bsi_start (bb); !bsi_end_p (bsi); )
3405 tree stmt = bsi_stmt (bsi);
3407 err |= verify_stmt (stmt, bsi_end_p (bsi));
3408 addr = walk_tree (&stmt, verify_node_sharing, htab, NULL);
3411 error ("Incorrect sharing of tree nodes");
3412 debug_generic_stmt (stmt);
3413 debug_generic_stmt (addr);
3420 internal_error ("verify_stmts failed.");
3423 timevar_pop (TV_TREE_STMT_VERIFY);
3427 /* Verifies that the flow information is OK. */
3430 tree_verify_flow_info (void)
3434 block_stmt_iterator bsi;
3439 if (ENTRY_BLOCK_PTR->stmt_list)
3441 error ("ENTRY_BLOCK has a statement list associated with it\n");
3445 if (EXIT_BLOCK_PTR->stmt_list)
3447 error ("EXIT_BLOCK has a statement list associated with it\n");
3451 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
3452 if (e->flags & EDGE_FALLTHRU)
3454 error ("Fallthru to exit from bb %d\n", e->src->index);
3460 bool found_ctrl_stmt = false;
3462 /* Skip labels on the start of basic block. */
3463 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3465 if (TREE_CODE (bsi_stmt (bsi)) != LABEL_EXPR)
3468 if (label_to_block (LABEL_EXPR_LABEL (bsi_stmt (bsi))) != bb)
3470 error ("Label %s to block does not match in bb %d\n",
3471 IDENTIFIER_POINTER (DECL_NAME (bsi_stmt (bsi))),
3476 if (decl_function_context (LABEL_EXPR_LABEL (bsi_stmt (bsi)))
3477 != current_function_decl)
3479 error ("Label %s has incorrect context in bb %d\n",
3480 IDENTIFIER_POINTER (DECL_NAME (bsi_stmt (bsi))),
3486 /* Verify that body of basic block BB is free of control flow. */
3487 for (; !bsi_end_p (bsi); bsi_next (&bsi))
3489 tree stmt = bsi_stmt (bsi);
3491 if (found_ctrl_stmt)
3493 error ("Control flow in the middle of basic block %d\n",
3498 if (stmt_ends_bb_p (stmt))
3499 found_ctrl_stmt = true;
3501 if (TREE_CODE (stmt) == LABEL_EXPR)
3503 error ("Label %s in the middle of basic block %d\n",
3504 IDENTIFIER_POINTER (DECL_NAME (stmt)),
3509 bsi = bsi_last (bb);
3510 if (bsi_end_p (bsi))
3513 stmt = bsi_stmt (bsi);
3515 if (is_ctrl_stmt (stmt))
3517 FOR_EACH_EDGE (e, ei, bb->succs)
3518 if (e->flags & EDGE_FALLTHRU)
3520 error ("Fallthru edge after a control statement in bb %d \n",
3526 switch (TREE_CODE (stmt))
3532 if (TREE_CODE (COND_EXPR_THEN (stmt)) != GOTO_EXPR
3533 || TREE_CODE (COND_EXPR_ELSE (stmt)) != GOTO_EXPR)
3535 error ("Structured COND_EXPR at the end of bb %d\n", bb->index);
3539 extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
3541 if (!true_edge || !false_edge
3542 || !(true_edge->flags & EDGE_TRUE_VALUE)
3543 || !(false_edge->flags & EDGE_FALSE_VALUE)
3544 || (true_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL))
3545 || (false_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL))
3546 || EDGE_COUNT (bb->succs) >= 3)
3548 error ("Wrong outgoing edge flags at end of bb %d\n",
3553 if (!has_label_p (true_edge->dest,
3554 GOTO_DESTINATION (COND_EXPR_THEN (stmt))))
3556 error ("%<then%> label does not match edge at end of bb %d\n",
3561 if (!has_label_p (false_edge->dest,
3562 GOTO_DESTINATION (COND_EXPR_ELSE (stmt))))
3564 error ("%<else%> label does not match edge at end of bb %d\n",
3572 if (simple_goto_p (stmt))
3574 error ("Explicit goto at end of bb %d\n", bb->index);
3579 /* FIXME. We should double check that the labels in the
3580 destination blocks have their address taken. */
3581 FOR_EACH_EDGE (e, ei, bb->succs)
3582 if ((e->flags & (EDGE_FALLTHRU | EDGE_TRUE_VALUE
3583 | EDGE_FALSE_VALUE))
3584 || !(e->flags & EDGE_ABNORMAL))
3586 error ("Wrong outgoing edge flags at end of bb %d\n",
3594 if (EDGE_COUNT (bb->succs) != 1
3595 || (EDGE_SUCC (bb, 0)->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL
3596 | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
3598 error ("Wrong outgoing edge flags at end of bb %d\n", bb->index);
3601 if (EDGE_SUCC (bb, 0)->dest != EXIT_BLOCK_PTR)
3603 error ("Return edge does not point to exit in bb %d\n",
3616 vec = SWITCH_LABELS (stmt);
3617 n = TREE_VEC_LENGTH (vec);
3619 /* Mark all the destination basic blocks. */
3620 for (i = 0; i < n; ++i)
3622 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
3623 basic_block label_bb = label_to_block (lab);
3625 gcc_assert (!label_bb->aux || label_bb->aux == (void *)1);
3626 label_bb->aux = (void *)1;
3629 /* Verify that the case labels are sorted. */
3630 prev = TREE_VEC_ELT (vec, 0);
3631 for (i = 1; i < n - 1; ++i)
3633 tree c = TREE_VEC_ELT (vec, i);
3636 error ("Found default case not at end of case vector");
3640 if (! tree_int_cst_lt (CASE_LOW (prev), CASE_LOW (c)))
3642 error ("Case labels not sorted:\n ");
3643 print_generic_expr (stderr, prev, 0);
3644 fprintf (stderr," is greater than ");
3645 print_generic_expr (stderr, c, 0);
3646 fprintf (stderr," but comes before it.\n");
3651 if (CASE_LOW (TREE_VEC_ELT (vec, n - 1)))
3653 error ("No default case found at end of case vector");
3657 FOR_EACH_EDGE (e, ei, bb->succs)
3661 error ("Extra outgoing edge %d->%d\n",
3662 bb->index, e->dest->index);
3665 e->dest->aux = (void *)2;
3666 if ((e->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL
3667 | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
3669 error ("Wrong outgoing edge flags at end of bb %d\n",
3675 /* Check that we have all of them. */
3676 for (i = 0; i < n; ++i)
3678 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
3679 basic_block label_bb = label_to_block (lab);
3681 if (label_bb->aux != (void *)2)
3683 error ("Missing edge %i->%i\n",
3684 bb->index, label_bb->index);
3689 FOR_EACH_EDGE (e, ei, bb->succs)
3690 e->dest->aux = (void *)0;
3697 if (dom_computed[CDI_DOMINATORS] >= DOM_NO_FAST_QUERY)
3698 verify_dominators (CDI_DOMINATORS);
3704 /* Updates phi nodes after creating forwarder block joined
3705 by edge FALLTHRU. */
3708 tree_make_forwarder_block (edge fallthru)
3712 basic_block dummy, bb;
3713 tree phi, new_phi, var, prev, next;
3715 dummy = fallthru->src;
3716 bb = fallthru->dest;
3718 if (EDGE_COUNT (bb->preds) == 1)
3721 /* If we redirected a branch we must create new phi nodes at the
3723 for (phi = phi_nodes (dummy); phi; phi = PHI_CHAIN (phi))
3725 var = PHI_RESULT (phi);
3726 new_phi = create_phi_node (var, bb);
3727 SSA_NAME_DEF_STMT (var) = new_phi;
3728 SET_PHI_RESULT (phi, make_ssa_name (SSA_NAME_VAR (var), phi));
3729 add_phi_arg (&new_phi, PHI_RESULT (phi), fallthru);
3732 /* Ensure that the PHI node chain is in the same order. */
3734 for (phi = phi_nodes (bb); phi; phi = next)
3736 next = PHI_CHAIN (phi);
3737 PHI_CHAIN (phi) = prev;
3740 set_phi_nodes (bb, prev);
3742 /* Add the arguments we have stored on edges. */
3743 FOR_EACH_EDGE (e, ei, bb->preds)
3748 for (phi = phi_nodes (bb), var = PENDING_STMT (e);
3750 phi = PHI_CHAIN (phi), var = TREE_CHAIN (var))
3751 add_phi_arg (&phi, TREE_VALUE (var), e);
3753 PENDING_STMT (e) = NULL;
3758 /* Return true if basic block BB does nothing except pass control
3759 flow to another block and that we can safely insert a label at
3760 the start of the successor block. */
3763 tree_forwarder_block_p (basic_block bb)
3765 block_stmt_iterator bsi;
3769 /* If we have already determined that this block is not forwardable,
3770 then no further checks are necessary. */
3771 if (! bb_ann (bb)->forwardable)
3774 /* BB must have a single outgoing normal edge. Otherwise it can not be
3775 a forwarder block. */
3776 if (EDGE_COUNT (bb->succs) != 1
3777 || EDGE_SUCC (bb, 0)->dest == EXIT_BLOCK_PTR
3778 || (EDGE_SUCC (bb, 0)->flags & EDGE_ABNORMAL)
3779 || bb == ENTRY_BLOCK_PTR)
3781 bb_ann (bb)->forwardable = 0;
3785 /* Successors of the entry block are not forwarders. */
3786 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
3789 bb_ann (bb)->forwardable = 0;
3793 /* BB can not have any PHI nodes. This could potentially be relaxed
3794 early in compilation if we re-rewrote the variables appearing in
3795 any PHI nodes in forwarder blocks. */
3798 bb_ann (bb)->forwardable = 0;
3802 /* Now walk through the statements. We can ignore labels, anything else
3803 means this is not a forwarder block. */
3804 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3806 tree stmt = bsi_stmt (bsi);
3808 switch (TREE_CODE (stmt))
3811 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)))
3816 bb_ann (bb)->forwardable = 0;
3825 /* Thread jumps over empty statements.
3827 This code should _not_ thread over obviously equivalent conditions
3828 as that requires nontrivial updates to the SSA graph.
3830 As a precondition, we require that all basic blocks be reachable.
3831 That is, there should be no opportunities left for
3832 delete_unreachable_blocks. */
3838 basic_block bb, dest, tmp, old_dest, curr, dom;
3841 bool retval = false;
3844 bb_ann (bb)->forwardable = 1;
3850 /* Don't waste time on forwarders. */
3851 if (tree_forwarder_block_p (bb))
3854 /* This block is now part of a forwarding path, mark it as not
3855 forwardable so that we can detect loops. This bit will be
3857 bb_ann (bb)->forwardable = 0;
3859 /* Examine each of our block's successors to see if it is
3861 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
3866 /* If the edge is abnormal or its destination is not
3867 forwardable, then there's nothing to do. */
3868 if ((e->flags & EDGE_ABNORMAL)
3869 || !tree_forwarder_block_p (e->dest))
3876 freq = EDGE_FREQUENCY (e);
3878 /* Now walk through as many forwarder blocks as possible to
3879 find the ultimate destination we want to thread our jump
3881 last = EDGE_SUCC (e->dest, 0);
3882 bb_ann (e->dest)->forwardable = 0;
3883 for (dest = EDGE_SUCC (e->dest, 0)->dest;
3884 tree_forwarder_block_p (dest);
3885 last = EDGE_SUCC (dest, 0),
3886 dest = EDGE_SUCC (dest, 0)->dest)
3887 bb_ann (dest)->forwardable = 0;
3889 /* Reset the forwardable marks to 1. */
3892 tmp = EDGE_SUCC (tmp, 0)->dest)
3893 bb_ann (tmp)->forwardable = 1;
3895 if (dest == e->dest)
3901 old = find_edge (bb, dest);
3904 /* If there already is an edge, check whether the values
3905 in phi nodes differ. */
3906 if (!phi_alternatives_equal (dest, last, old))
3908 /* The previous block is forwarder. Redirect our jump
3909 to that target instead since we know it has no PHI
3910 nodes that will need updating. */
3913 /* That might mean that no forwarding at all is possible. */
3914 if (dest == e->dest)
3920 old = find_edge (bb, dest);
3924 /* Perform the redirection. */
3927 e = redirect_edge_and_branch (e, dest);
3929 /* Update the profile. */
3930 if (profile_status != PROFILE_ABSENT)
3931 for (curr = old_dest; curr != dest; curr = EDGE_SUCC (curr, 0)->dest)
3933 curr->frequency -= freq;
3934 if (curr->frequency < 0)
3935 curr->frequency = 0;
3936 curr->count -= count;
3937 if (curr->count < 0)
3939 EDGE_SUCC (curr, 0)->count -= count;
3940 if (EDGE_SUCC (curr, 0)->count < 0)
3941 EDGE_SUCC (curr, 0)->count = 0;
3946 /* Update PHI nodes. We know that the new argument should
3947 have the same value as the argument associated with LAST.
3948 Otherwise we would have changed our target block above. */
3949 for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi))
3951 arg = phi_arg_from_edge (phi, last);
3952 gcc_assert (arg >= 0);
3953 add_phi_arg (&phi, PHI_ARG_DEF (phi, arg), e);
3957 /* Remove the unreachable blocks (observe that if all blocks
3958 were reachable before, only those in the path we threaded
3959 over and did not have any predecessor outside of the path
3960 become unreachable). */
3961 for (; old_dest != dest; old_dest = tmp)
3963 tmp = EDGE_SUCC (old_dest, 0)->dest;
3965 if (EDGE_COUNT (old_dest->preds) > 0)
3968 delete_basic_block (old_dest);
3971 /* Update the dominators. */
3972 if (dom_computed[CDI_DOMINATORS] >= DOM_CONS_OK)
3974 /* If the dominator of the destination was in the path, set its
3975 dominator to the start of the redirected edge. */
3976 if (get_immediate_dominator (CDI_DOMINATORS, old_dest) == NULL)
3977 set_immediate_dominator (CDI_DOMINATORS, old_dest, bb);
3979 /* Now proceed like if we forwarded just over one edge at a time.
3980 Algorithm for forwarding edge S --> A over edge A --> B then
3984 && !dominated_by (S, B))
3985 idom (B) = idom (A);
3986 recount_idom (A); */
3988 for (; old_dest != dest; old_dest = tmp)
3990 tmp = EDGE_SUCC (old_dest, 0)->dest;
3992 if (get_immediate_dominator (CDI_DOMINATORS, tmp) == old_dest
3993 && !dominated_by_p (CDI_DOMINATORS, bb, tmp))
3995 dom = get_immediate_dominator (CDI_DOMINATORS, old_dest);
3996 set_immediate_dominator (CDI_DOMINATORS, tmp, dom);
3999 dom = recount_dominator (CDI_DOMINATORS, old_dest);
4000 set_immediate_dominator (CDI_DOMINATORS, old_dest, dom);
4005 /* Reset the forwardable bit on our block since it's no longer in
4006 a forwarding chain path. */
4007 bb_ann (bb)->forwardable = 1;
4014 /* Return a non-special label in the head of basic block BLOCK.
4015 Create one if it doesn't exist. */
4018 tree_block_label (basic_block bb)
4020 block_stmt_iterator i, s = bsi_start (bb);
4024 for (i = s; !bsi_end_p (i); first = false, bsi_next (&i))
4026 stmt = bsi_stmt (i);
4027 if (TREE_CODE (stmt) != LABEL_EXPR)
4029 label = LABEL_EXPR_LABEL (stmt);
4030 if (!DECL_NONLOCAL (label))
4033 bsi_move_before (&i, &s);
4038 label = create_artificial_label ();
4039 stmt = build1 (LABEL_EXPR, void_type_node, label);
4040 bsi_insert_before (&s, stmt, BSI_NEW_STMT);
4045 /* Attempt to perform edge redirection by replacing a possibly complex
4046 jump instruction by a goto or by removing the jump completely.
4047 This can apply only if all edges now point to the same block. The
4048 parameters and return values are equivalent to
4049 redirect_edge_and_branch. */
4052 tree_try_redirect_by_replacing_jump (edge e, basic_block target)
4054 basic_block src = e->src;
4056 block_stmt_iterator b;
4060 /* Verify that all targets will be TARGET. */
4061 FOR_EACH_EDGE (tmp, ei, src->succs)
4062 if (tmp->dest != target && tmp != e)
4071 stmt = bsi_stmt (b);
4073 if (TREE_CODE (stmt) == COND_EXPR
4074 || TREE_CODE (stmt) == SWITCH_EXPR)
4077 e = ssa_redirect_edge (e, target);
4078 e->flags = EDGE_FALLTHRU;
4086 /* Redirect E to DEST. Return NULL on failure. Otherwise, return the
4087 edge representing the redirected branch. */
4090 tree_redirect_edge_and_branch (edge e, basic_block dest)
4092 basic_block bb = e->src;
4093 block_stmt_iterator bsi;
4097 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
4100 if (e->src != ENTRY_BLOCK_PTR
4101 && (ret = tree_try_redirect_by_replacing_jump (e, dest)))
4104 if (e->dest == dest)
4107 label = tree_block_label (dest);
4109 bsi = bsi_last (bb);
4110 stmt = bsi_end_p (bsi) ? NULL : bsi_stmt (bsi);
4112 switch (stmt ? TREE_CODE (stmt) : ERROR_MARK)
4115 stmt = (e->flags & EDGE_TRUE_VALUE
4116 ? COND_EXPR_THEN (stmt)
4117 : COND_EXPR_ELSE (stmt));
4118 GOTO_DESTINATION (stmt) = label;
4122 /* No non-abnormal edges should lead from a non-simple goto, and
4123 simple ones should be represented implicitly. */
4128 tree vec = SWITCH_LABELS (stmt);
4129 size_t i, n = TREE_VEC_LENGTH (vec);
4131 for (i = 0; i < n; ++i)
4133 tree elt = TREE_VEC_ELT (vec, i);
4134 if (label_to_block (CASE_LABEL (elt)) == e->dest)
4135 CASE_LABEL (elt) = label;
4142 e->flags |= EDGE_FALLTHRU;
4146 /* Otherwise it must be a fallthru edge, and we don't need to
4147 do anything besides redirecting it. */
4148 gcc_assert (e->flags & EDGE_FALLTHRU);
4152 /* Update/insert PHI nodes as necessary. */
4154 /* Now update the edges in the CFG. */
4155 e = ssa_redirect_edge (e, dest);
4161 /* Simple wrapper, as we can always redirect fallthru edges. */
4164 tree_redirect_edge_and_branch_force (edge e, basic_block dest)
4166 e = tree_redirect_edge_and_branch (e, dest);
4173 /* Splits basic block BB after statement STMT (but at least after the
4174 labels). If STMT is NULL, BB is split just after the labels. */
4177 tree_split_block (basic_block bb, void *stmt)
4179 block_stmt_iterator bsi, bsi_tgt;
4185 new_bb = create_empty_bb (bb);
4187 /* Redirect the outgoing edges. */
4188 new_bb->succs = bb->succs;
4190 FOR_EACH_EDGE (e, ei, new_bb->succs)
4193 if (stmt && TREE_CODE ((tree) stmt) == LABEL_EXPR)
4196 /* Move everything from BSI to the new basic block. */
4197 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4199 act = bsi_stmt (bsi);
4200 if (TREE_CODE (act) == LABEL_EXPR)
4213 bsi_tgt = bsi_start (new_bb);
4214 while (!bsi_end_p (bsi))
4216 act = bsi_stmt (bsi);
4218 bsi_insert_after (&bsi_tgt, act, BSI_NEW_STMT);
4225 /* Moves basic block BB after block AFTER. */
4228 tree_move_block_after (basic_block bb, basic_block after)
4230 if (bb->prev_bb == after)
4234 link_block (bb, after);
4240 /* Return true if basic_block can be duplicated. */
4243 tree_can_duplicate_bb_p (basic_block bb ATTRIBUTE_UNUSED)
4248 /* Create a duplicate of the basic block BB. NOTE: This does not
4249 preserve SSA form. */
4252 tree_duplicate_bb (basic_block bb)
4255 block_stmt_iterator bsi, bsi_tgt;
4257 ssa_op_iter op_iter;
4259 new_bb = create_empty_bb (EXIT_BLOCK_PTR->prev_bb);
4261 /* First copy the phi nodes. We do not copy phi node arguments here,
4262 since the edges are not ready yet. Keep the chain of phi nodes in
4263 the same order, so that we can add them later. */
4264 for (phi = phi_nodes (bb); phi; phi = TREE_CHAIN (phi))
4266 mark_for_rewrite (PHI_RESULT (phi));
4267 create_phi_node (PHI_RESULT (phi), new_bb);
4269 set_phi_nodes (new_bb, nreverse (phi_nodes (new_bb)));
4271 bsi_tgt = bsi_start (new_bb);
4272 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4274 tree stmt = bsi_stmt (bsi);
4277 if (TREE_CODE (stmt) == LABEL_EXPR)
4280 /* Record the definitions. */
4281 get_stmt_operands (stmt);
4283 FOR_EACH_SSA_TREE_OPERAND (val, stmt, op_iter, SSA_OP_ALL_DEFS)
4284 mark_for_rewrite (val);
4286 copy = unshare_expr (stmt);
4288 /* Copy also the virtual operands. */
4289 get_stmt_ann (copy);
4290 copy_virtual_operands (copy, stmt);
4292 bsi_insert_after (&bsi_tgt, copy, BSI_NEW_STMT);
4298 /* Basic block BB_COPY was created by code duplication. Add phi node
4299 arguments for edges going out of BB_COPY. The blocks that were
4300 duplicated have rbi->duplicated set to one. */
4303 add_phi_args_after_copy_bb (basic_block bb_copy)
4305 basic_block bb, dest;
4308 tree phi, phi_copy, phi_next, def;
4310 bb = bb_copy->rbi->original;
4312 FOR_EACH_EDGE (e_copy, ei, bb_copy->succs)
4314 if (!phi_nodes (e_copy->dest))
4317 if (e_copy->dest->rbi->duplicated)
4318 dest = e_copy->dest->rbi->original;
4320 dest = e_copy->dest;
4322 e = find_edge (bb, dest);
4325 /* During loop unrolling the target of the latch edge is copied.
4326 In this case we are not looking for edge to dest, but to
4327 duplicated block whose original was dest. */
4328 FOR_EACH_EDGE (e, ei, bb->succs)
4329 if (e->dest->rbi->duplicated
4330 && e->dest->rbi->original == dest)
4333 gcc_assert (e != NULL);
4336 for (phi = phi_nodes (e->dest), phi_copy = phi_nodes (e_copy->dest);
4338 phi = phi_next, phi_copy = TREE_CHAIN (phi_copy))
4340 phi_next = TREE_CHAIN (phi);
4342 gcc_assert (PHI_RESULT (phi) == PHI_RESULT (phi_copy));
4343 def = PHI_ARG_DEF_FROM_EDGE (phi, e);
4344 add_phi_arg (&phi_copy, def, e_copy);
4349 /* Blocks in REGION_COPY array of length N_REGION were created by
4350 duplication of basic blocks. Add phi node arguments for edges
4351 going from these blocks. */
4354 add_phi_args_after_copy (basic_block *region_copy, unsigned n_region)
4358 for (i = 0; i < n_region; i++)
4359 region_copy[i]->rbi->duplicated = 1;
4361 for (i = 0; i < n_region; i++)
4362 add_phi_args_after_copy_bb (region_copy[i]);
4364 for (i = 0; i < n_region; i++)
4365 region_copy[i]->rbi->duplicated = 0;
4368 /* Maps the old ssa name FROM_NAME to TO_NAME. */
4370 struct ssa_name_map_entry
4376 /* Hash function for ssa_name_map_entry. */
4379 ssa_name_map_entry_hash (const void *entry)
4381 const struct ssa_name_map_entry *en = entry;
4382 return SSA_NAME_VERSION (en->from_name);
4385 /* Equality function for ssa_name_map_entry. */
4388 ssa_name_map_entry_eq (const void *in_table, const void *ssa_name)
4390 const struct ssa_name_map_entry *en = in_table;
4392 return en->from_name == ssa_name;
4395 /* Allocate duplicates of ssa names in list DEFINITIONS and store the mapping
4399 allocate_ssa_names (bitmap definitions, htab_t *map)
4402 struct ssa_name_map_entry *entry;
4408 *map = htab_create (10, ssa_name_map_entry_hash,
4409 ssa_name_map_entry_eq, free);
4410 EXECUTE_IF_SET_IN_BITMAP (definitions, 0, ver, bi)
4412 name = ssa_name (ver);
4413 slot = htab_find_slot_with_hash (*map, name, SSA_NAME_VERSION (name),
4419 entry = xmalloc (sizeof (struct ssa_name_map_entry));
4420 entry->from_name = name;
4423 entry->to_name = duplicate_ssa_name (name, SSA_NAME_DEF_STMT (name));
4427 /* Rewrite the definition DEF in statement STMT to new ssa name as specified
4428 by the mapping MAP. */
4431 rewrite_to_new_ssa_names_def (def_operand_p def, tree stmt, htab_t map)
4433 tree name = DEF_FROM_PTR (def);
4434 struct ssa_name_map_entry *entry;
4436 gcc_assert (TREE_CODE (name) == SSA_NAME);
4438 entry = htab_find_with_hash (map, name, SSA_NAME_VERSION (name));
4442 SET_DEF (def, entry->to_name);
4443 SSA_NAME_DEF_STMT (entry->to_name) = stmt;
4446 /* Rewrite the USE to new ssa name as specified by the mapping MAP. */
4449 rewrite_to_new_ssa_names_use (use_operand_p use, htab_t map)
4451 tree name = USE_FROM_PTR (use);
4452 struct ssa_name_map_entry *entry;
4454 if (TREE_CODE (name) != SSA_NAME)
4457 entry = htab_find_with_hash (map, name, SSA_NAME_VERSION (name));
4461 SET_USE (use, entry->to_name);
4464 /* Rewrite the ssa names in basic block BB to new ones as specified by the
4468 rewrite_to_new_ssa_names_bb (basic_block bb, htab_t map)
4474 block_stmt_iterator bsi;
4478 v_may_def_optype v_may_defs;
4479 v_must_def_optype v_must_defs;
4482 FOR_EACH_EDGE (e, ei, bb->preds)
4483 if (e->flags & EDGE_ABNORMAL)
4486 for (phi = phi_nodes (bb); phi; phi = TREE_CHAIN (phi))
4488 rewrite_to_new_ssa_names_def (PHI_RESULT_PTR (phi), phi, map);
4490 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (PHI_RESULT (phi)) = 1;
4493 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4495 stmt = bsi_stmt (bsi);
4496 get_stmt_operands (stmt);
4497 ann = stmt_ann (stmt);
4499 uses = USE_OPS (ann);
4500 for (i = 0; i < NUM_USES (uses); i++)
4501 rewrite_to_new_ssa_names_use (USE_OP_PTR (uses, i), map);
4503 defs = DEF_OPS (ann);
4504 for (i = 0; i < NUM_DEFS (defs); i++)
4505 rewrite_to_new_ssa_names_def (DEF_OP_PTR (defs, i), stmt, map);
4507 vuses = VUSE_OPS (ann);
4508 for (i = 0; i < NUM_VUSES (vuses); i++)
4509 rewrite_to_new_ssa_names_use (VUSE_OP_PTR (vuses, i), map);
4511 v_may_defs = V_MAY_DEF_OPS (ann);
4512 for (i = 0; i < NUM_V_MAY_DEFS (v_may_defs); i++)
4514 rewrite_to_new_ssa_names_use
4515 (V_MAY_DEF_OP_PTR (v_may_defs, i), map);
4516 rewrite_to_new_ssa_names_def
4517 (V_MAY_DEF_RESULT_PTR (v_may_defs, i), stmt, map);
4520 v_must_defs = V_MUST_DEF_OPS (ann);
4521 for (i = 0; i < NUM_V_MUST_DEFS (v_must_defs); i++)
4522 rewrite_to_new_ssa_names_def
4523 (V_MUST_DEF_OP_PTR (v_must_defs, i), stmt, map);
4526 FOR_EACH_EDGE (e, ei, bb->succs)
4527 for (phi = phi_nodes (e->dest); phi; phi = TREE_CHAIN (phi))
4529 rewrite_to_new_ssa_names_use
4530 (PHI_ARG_DEF_PTR_FROM_EDGE (phi, e), map);
4532 if (e->flags & EDGE_ABNORMAL)
4534 tree op = PHI_ARG_DEF_FROM_EDGE (phi, e);
4535 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op) = 1;
4540 /* Rewrite the ssa names in N_REGION blocks REGION to the new ones as specified
4541 by the mapping MAP. */
4544 rewrite_to_new_ssa_names (basic_block *region, unsigned n_region, htab_t map)
4548 for (r = 0; r < n_region; r++)
4549 rewrite_to_new_ssa_names_bb (region[r], map);
4552 /* Duplicates a REGION (set of N_REGION basic blocks) with just a single
4553 important exit edge EXIT. By important we mean that no SSA name defined
4554 inside region is live over the other exit edges of the region. All entry
4555 edges to the region must go to ENTRY->dest. The edge ENTRY is redirected
4556 to the duplicate of the region. SSA form, dominance and loop information
4557 is updated. The new basic blocks are stored to REGION_COPY in the same
4558 order as they had in REGION, provided that REGION_COPY is not NULL.
4559 The function returns false if it is unable to copy the region,
4563 tree_duplicate_sese_region (edge entry, edge exit,
4564 basic_block *region, unsigned n_region,
4565 basic_block *region_copy)
4567 unsigned i, n_doms, ver;
4568 bool free_region_copy = false, copying_header = false;
4569 struct loop *loop = entry->dest->loop_father;
4574 htab_t ssa_name_map = NULL;
4578 if (!can_copy_bbs_p (region, n_region))
4581 /* Some sanity checking. Note that we do not check for all possible
4582 missuses of the functions. I.e. if you ask to copy something weird,
4583 it will work, but the state of structures probably will not be
4586 for (i = 0; i < n_region; i++)
4588 /* We do not handle subloops, i.e. all the blocks must belong to the
4590 if (region[i]->loop_father != loop)
4593 if (region[i] != entry->dest
4594 && region[i] == loop->header)
4600 /* In case the function is used for loop header copying (which is the primary
4601 use), ensure that EXIT and its copy will be new latch and entry edges. */
4602 if (loop->header == entry->dest)
4604 copying_header = true;
4605 loop->copy = loop->outer;
4607 if (!dominated_by_p (CDI_DOMINATORS, loop->latch, exit->src))
4610 for (i = 0; i < n_region; i++)
4611 if (region[i] != exit->src
4612 && dominated_by_p (CDI_DOMINATORS, region[i], exit->src))
4618 region_copy = xmalloc (sizeof (basic_block) * n_region);
4619 free_region_copy = true;
4622 gcc_assert (!any_marked_for_rewrite_p ());
4624 /* Record blocks outside the region that are duplicated by something
4626 doms = xmalloc (sizeof (basic_block) * n_basic_blocks);
4627 n_doms = get_dominated_by_region (CDI_DOMINATORS, region, n_region, doms);
4629 copy_bbs (region, n_region, region_copy, &exit, 1, &exit_copy, loop);
4630 definitions = marked_ssa_names ();
4634 loop->header = exit->dest;
4635 loop->latch = exit->src;
4638 /* Redirect the entry and add the phi node arguments. */
4639 redirected = redirect_edge_and_branch (entry, entry->dest->rbi->copy);
4640 gcc_assert (redirected != NULL);
4641 for (phi = phi_nodes (entry->dest), var = PENDING_STMT (entry);
4643 phi = TREE_CHAIN (phi), var = TREE_CHAIN (var))
4644 add_phi_arg (&phi, TREE_VALUE (var), entry);
4645 PENDING_STMT (entry) = NULL;
4647 /* Concerning updating of dominators: We must recount dominators
4648 for entry block and its copy. Anything that is outside of the region, but
4649 was dominated by something inside needs recounting as well. */
4650 set_immediate_dominator (CDI_DOMINATORS, entry->dest, entry->src);
4651 doms[n_doms++] = entry->dest->rbi->original;
4652 iterate_fix_dominators (CDI_DOMINATORS, doms, n_doms);
4655 /* Add the other phi node arguments. */
4656 add_phi_args_after_copy (region_copy, n_region);
4658 /* Add phi nodes for definitions at exit. TODO -- once we have immediate
4659 uses, it should be possible to emit phi nodes just for definitions that
4660 are used outside region. */
4661 EXECUTE_IF_SET_IN_BITMAP (definitions, 0, ver, bi)
4663 tree name = ssa_name (ver);
4665 phi = create_phi_node (name, exit->dest);
4666 add_phi_arg (&phi, name, exit);
4667 add_phi_arg (&phi, name, exit_copy);
4669 SSA_NAME_DEF_STMT (name) = phi;
4672 /* And create new definitions inside region and its copy. TODO -- once we
4673 have immediate uses, it might be better to leave definitions in region
4674 unchanged, create new ssa names for phi nodes on exit, and rewrite
4675 the uses, to avoid changing the copied region. */
4676 allocate_ssa_names (definitions, &ssa_name_map);
4677 rewrite_to_new_ssa_names (region, n_region, ssa_name_map);
4678 allocate_ssa_names (definitions, &ssa_name_map);
4679 rewrite_to_new_ssa_names (region_copy, n_region, ssa_name_map);
4680 htab_delete (ssa_name_map);
4682 if (free_region_copy)
4685 unmark_all_for_rewrite ();
4686 BITMAP_XFREE (definitions);
4691 /* Dump FUNCTION_DECL FN to file FILE using FLAGS (see TDF_* in tree.h) */
4694 dump_function_to_file (tree fn, FILE *file, int flags)
4696 tree arg, vars, var;
4697 bool ignore_topmost_bind = false, any_var = false;
4701 fprintf (file, "%s (", lang_hooks.decl_printable_name (fn, 2));
4703 arg = DECL_ARGUMENTS (fn);
4706 print_generic_expr (file, arg, dump_flags);
4707 if (TREE_CHAIN (arg))
4708 fprintf (file, ", ");
4709 arg = TREE_CHAIN (arg);
4711 fprintf (file, ")\n");
4713 if (flags & TDF_RAW)
4715 dump_node (fn, TDF_SLIM | flags, file);
4719 /* When GIMPLE is lowered, the variables are no longer available in
4720 BIND_EXPRs, so display them separately. */
4721 if (cfun && cfun->unexpanded_var_list)
4723 ignore_topmost_bind = true;
4725 fprintf (file, "{\n");
4726 for (vars = cfun->unexpanded_var_list; vars; vars = TREE_CHAIN (vars))
4728 var = TREE_VALUE (vars);
4730 print_generic_decl (file, var, flags);
4731 fprintf (file, "\n");
4737 if (basic_block_info)
4739 /* Make a CFG based dump. */
4740 check_bb_profile (ENTRY_BLOCK_PTR, file);
4741 if (!ignore_topmost_bind)
4742 fprintf (file, "{\n");
4744 if (any_var && n_basic_blocks)
4745 fprintf (file, "\n");
4748 dump_generic_bb (file, bb, 2, flags);
4750 fprintf (file, "}\n");
4751 check_bb_profile (EXIT_BLOCK_PTR, file);
4757 /* Make a tree based dump. */
4758 chain = DECL_SAVED_TREE (fn);
4760 if (TREE_CODE (chain) == BIND_EXPR)
4762 if (ignore_topmost_bind)
4764 chain = BIND_EXPR_BODY (chain);
4772 if (!ignore_topmost_bind)
4773 fprintf (file, "{\n");
4778 fprintf (file, "\n");
4780 print_generic_stmt_indented (file, chain, flags, indent);
4781 if (ignore_topmost_bind)
4782 fprintf (file, "}\n");
4785 fprintf (file, "\n\n");
4789 /* Pretty print of the loops intermediate representation. */
4790 static void print_loop (FILE *, struct loop *, int);
4791 static void print_pred_bbs (FILE *, basic_block bb);
4792 static void print_succ_bbs (FILE *, basic_block bb);
4795 /* Print the predecessors indexes of edge E on FILE. */
4798 print_pred_bbs (FILE *file, basic_block bb)
4803 FOR_EACH_EDGE (e, ei, bb->preds)
4804 fprintf (file, "bb_%d", e->src->index);
4808 /* Print the successors indexes of edge E on FILE. */
4811 print_succ_bbs (FILE *file, basic_block bb)
4816 FOR_EACH_EDGE (e, ei, bb->succs)
4817 fprintf (file, "bb_%d", e->src->index);
4821 /* Pretty print LOOP on FILE, indented INDENT spaces. */
4824 print_loop (FILE *file, struct loop *loop, int indent)
4832 s_indent = (char *) alloca ((size_t) indent + 1);
4833 memset ((void *) s_indent, ' ', (size_t) indent);
4834 s_indent[indent] = '\0';
4836 /* Print the loop's header. */
4837 fprintf (file, "%sloop_%d\n", s_indent, loop->num);
4839 /* Print the loop's body. */
4840 fprintf (file, "%s{\n", s_indent);
4842 if (bb->loop_father == loop)
4844 /* Print the basic_block's header. */
4845 fprintf (file, "%s bb_%d (preds = {", s_indent, bb->index);
4846 print_pred_bbs (file, bb);
4847 fprintf (file, "}, succs = {");
4848 print_succ_bbs (file, bb);
4849 fprintf (file, "})\n");
4851 /* Print the basic_block's body. */
4852 fprintf (file, "%s {\n", s_indent);
4853 tree_dump_bb (bb, file, indent + 4);
4854 fprintf (file, "%s }\n", s_indent);
4857 print_loop (file, loop->inner, indent + 2);
4858 fprintf (file, "%s}\n", s_indent);
4859 print_loop (file, loop->next, indent);
4863 /* Follow a CFG edge from the entry point of the program, and on entry
4864 of a loop, pretty print the loop structure on FILE. */
4867 print_loop_ir (FILE *file)
4871 bb = BASIC_BLOCK (0);
4872 if (bb && bb->loop_father)
4873 print_loop (file, bb->loop_father, 0);
4877 /* Debugging loops structure at tree level. */
4880 debug_loop_ir (void)
4882 print_loop_ir (stderr);
4886 /* Return true if BB ends with a call, possibly followed by some
4887 instructions that must stay with the call. Return false,
4891 tree_block_ends_with_call_p (basic_block bb)
4893 block_stmt_iterator bsi = bsi_last (bb);
4894 return get_call_expr_in (bsi_stmt (bsi)) != NULL;
4898 /* Return true if BB ends with a conditional branch. Return false,
4902 tree_block_ends_with_condjump_p (basic_block bb)
4904 tree stmt = tsi_stmt (bsi_last (bb).tsi);
4905 return (TREE_CODE (stmt) == COND_EXPR);
4909 /* Return true if we need to add fake edge to exit at statement T.
4910 Helper function for tree_flow_call_edges_add. */
4913 need_fake_edge_p (tree t)
4917 /* NORETURN and LONGJMP calls already have an edge to exit.
4918 CONST, PURE and ALWAYS_RETURN calls do not need one.
4919 We don't currently check for CONST and PURE here, although
4920 it would be a good idea, because those attributes are
4921 figured out from the RTL in mark_constant_function, and
4922 the counter incrementation code from -fprofile-arcs
4923 leads to different results from -fbranch-probabilities. */
4924 call = get_call_expr_in (t);
4926 && !(call_expr_flags (call) &
4927 (ECF_NORETURN | ECF_LONGJMP | ECF_ALWAYS_RETURN)))
4930 if (TREE_CODE (t) == ASM_EXPR
4931 && (ASM_VOLATILE_P (t) || ASM_INPUT_P (t)))
4938 /* Add fake edges to the function exit for any non constant and non
4939 noreturn calls, volatile inline assembly in the bitmap of blocks
4940 specified by BLOCKS or to the whole CFG if BLOCKS is zero. Return
4941 the number of blocks that were split.
4943 The goal is to expose cases in which entering a basic block does
4944 not imply that all subsequent instructions must be executed. */
4947 tree_flow_call_edges_add (sbitmap blocks)
4950 int blocks_split = 0;
4951 int last_bb = last_basic_block;
4952 bool check_last_block = false;
4954 if (n_basic_blocks == 0)
4958 check_last_block = true;
4960 check_last_block = TEST_BIT (blocks, EXIT_BLOCK_PTR->prev_bb->index);
4962 /* In the last basic block, before epilogue generation, there will be
4963 a fallthru edge to EXIT. Special care is required if the last insn
4964 of the last basic block is a call because make_edge folds duplicate
4965 edges, which would result in the fallthru edge also being marked
4966 fake, which would result in the fallthru edge being removed by
4967 remove_fake_edges, which would result in an invalid CFG.
4969 Moreover, we can't elide the outgoing fake edge, since the block
4970 profiler needs to take this into account in order to solve the minimal
4971 spanning tree in the case that the call doesn't return.
4973 Handle this by adding a dummy instruction in a new last basic block. */
4974 if (check_last_block)
4977 basic_block bb = EXIT_BLOCK_PTR->prev_bb;
4978 block_stmt_iterator bsi = bsi_last (bb);
4980 if (!bsi_end_p (bsi))
4983 if (need_fake_edge_p (t))
4987 FOR_EACH_EDGE (e, ei, bb->succs)
4988 if (e->dest == EXIT_BLOCK_PTR)
4990 bsi_insert_on_edge (e, build_empty_stmt ());
4991 bsi_commit_edge_inserts ((int *)NULL);
4997 /* Now add fake edges to the function exit for any non constant
4998 calls since there is no way that we can determine if they will
5000 for (i = 0; i < last_bb; i++)
5002 basic_block bb = BASIC_BLOCK (i);
5003 block_stmt_iterator bsi;
5004 tree stmt, last_stmt;
5009 if (blocks && !TEST_BIT (blocks, i))
5012 bsi = bsi_last (bb);
5013 if (!bsi_end_p (bsi))
5015 last_stmt = bsi_stmt (bsi);
5018 stmt = bsi_stmt (bsi);
5019 if (need_fake_edge_p (stmt))
5022 /* The handling above of the final block before the
5023 epilogue should be enough to verify that there is
5024 no edge to the exit block in CFG already.
5025 Calling make_edge in such case would cause us to
5026 mark that edge as fake and remove it later. */
5027 #ifdef ENABLE_CHECKING
5028 if (stmt == last_stmt)
5031 FOR_EACH_EDGE (e, ei, bb->succs)
5032 gcc_assert (e->dest != EXIT_BLOCK_PTR);
5036 /* Note that the following may create a new basic block
5037 and renumber the existing basic blocks. */
5038 if (stmt != last_stmt)
5040 e = split_block (bb, stmt);
5044 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
5048 while (!bsi_end_p (bsi));
5053 verify_flow_info ();
5055 return blocks_split;
5059 tree_purge_dead_eh_edges (basic_block bb)
5061 bool changed = false;
5064 tree stmt = last_stmt (bb);
5066 if (stmt && tree_can_throw_internal (stmt))
5069 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
5071 if (e->flags & EDGE_EH)
5073 ssa_remove_edge (e);
5084 tree_purge_all_dead_eh_edges (bitmap blocks)
5086 bool changed = false;
5090 EXECUTE_IF_SET_IN_BITMAP (blocks, 0, i, bi)
5092 changed |= tree_purge_dead_eh_edges (BASIC_BLOCK (i));
5098 struct cfg_hooks tree_cfg_hooks = {
5100 tree_verify_flow_info,
5101 tree_dump_bb, /* dump_bb */
5102 create_bb, /* create_basic_block */
5103 tree_redirect_edge_and_branch,/* redirect_edge_and_branch */
5104 tree_redirect_edge_and_branch_force,/* redirect_edge_and_branch_force */
5105 remove_bb, /* delete_basic_block */
5106 tree_split_block, /* split_block */
5107 tree_move_block_after, /* move_block_after */
5108 tree_can_merge_blocks_p, /* can_merge_blocks_p */
5109 tree_merge_blocks, /* merge_blocks */
5110 tree_predict_edge, /* predict_edge */
5111 tree_predicted_by_p, /* predicted_by_p */
5112 tree_can_duplicate_bb_p, /* can_duplicate_block_p */
5113 tree_duplicate_bb, /* duplicate_block */
5114 tree_split_edge, /* split_edge */
5115 tree_make_forwarder_block, /* make_forward_block */
5116 NULL, /* tidy_fallthru_edge */
5117 tree_block_ends_with_call_p, /* block_ends_with_call_p */
5118 tree_block_ends_with_condjump_p, /* block_ends_with_condjump_p */
5119 tree_flow_call_edges_add /* flow_call_edges_add */
5123 /* Split all critical edges. */
5126 split_critical_edges (void)
5134 FOR_EACH_EDGE (e, ei, bb->succs)
5135 if (EDGE_CRITICAL_P (e) && !(e->flags & EDGE_ABNORMAL))
5142 struct tree_opt_pass pass_split_crit_edges =
5144 "crited", /* name */
5146 split_critical_edges, /* execute */
5149 0, /* static_pass_number */
5150 TV_TREE_SPLIT_EDGES, /* tv_id */
5151 PROP_cfg, /* properties required */
5152 PROP_no_crit_edges, /* properties_provided */
5153 0, /* properties_destroyed */
5154 0, /* todo_flags_start */
5155 TODO_dump_func, /* todo_flags_finish */
5160 /* Return EXP if it is a valid GIMPLE rvalue, else gimplify it into
5161 a temporary, make sure and register it to be renamed if necessary,
5162 and finally return the temporary. Put the statements to compute
5163 EXP before the current statement in BSI. */
5166 gimplify_val (block_stmt_iterator *bsi, tree type, tree exp)
5168 tree t, new_stmt, orig_stmt;
5170 if (is_gimple_val (exp))
5173 t = make_rename_temp (type, NULL);
5174 new_stmt = build (MODIFY_EXPR, type, t, exp);
5176 orig_stmt = bsi_stmt (*bsi);
5177 SET_EXPR_LOCUS (new_stmt, EXPR_LOCUS (orig_stmt));
5178 TREE_BLOCK (new_stmt) = TREE_BLOCK (orig_stmt);
5180 bsi_insert_before (bsi, new_stmt, BSI_SAME_STMT);
5185 /* Build a ternary operation and gimplify it. Emit code before BSI.
5186 Return the gimple_val holding the result. */
5189 gimplify_build3 (block_stmt_iterator *bsi, enum tree_code code,
5190 tree type, tree a, tree b, tree c)
5194 ret = fold (build3 (code, type, a, b, c));
5197 return gimplify_val (bsi, type, ret);
5200 /* Build a binary operation and gimplify it. Emit code before BSI.
5201 Return the gimple_val holding the result. */
5204 gimplify_build2 (block_stmt_iterator *bsi, enum tree_code code,
5205 tree type, tree a, tree b)
5209 ret = fold (build2 (code, type, a, b));
5212 return gimplify_val (bsi, type, ret);
5215 /* Build a unary operation and gimplify it. Emit code before BSI.
5216 Return the gimple_val holding the result. */
5219 gimplify_build1 (block_stmt_iterator *bsi, enum tree_code code, tree type,
5224 ret = fold (build1 (code, type, a));
5227 return gimplify_val (bsi, type, ret);
5232 /* Emit return warnings. */
5235 execute_warn_function_return (void)
5237 #ifdef USE_MAPPED_LOCATION
5238 source_location location;
5246 if (warn_missing_noreturn
5247 && !TREE_THIS_VOLATILE (cfun->decl)
5248 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) == 0
5249 && !lang_hooks.function.missing_noreturn_ok_p (cfun->decl))
5250 warning ("%Jfunction might be possible candidate for "
5251 "attribute %<noreturn%>",
5254 /* If we have a path to EXIT, then we do return. */
5255 if (TREE_THIS_VOLATILE (cfun->decl)
5256 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) > 0)
5258 #ifdef USE_MAPPED_LOCATION
5259 location = UNKNOWN_LOCATION;
5263 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
5265 last = last_stmt (e->src);
5266 if (TREE_CODE (last) == RETURN_EXPR
5267 #ifdef USE_MAPPED_LOCATION
5268 && (location = EXPR_LOCATION (last)) != UNKNOWN_LOCATION)
5270 && (locus = EXPR_LOCUS (last)) != NULL)
5274 #ifdef USE_MAPPED_LOCATION
5275 if (location == UNKNOWN_LOCATION)
5276 location = cfun->function_end_locus;
5277 warning ("%H%<noreturn%> function does return", &location);
5280 locus = &cfun->function_end_locus;
5281 warning ("%H%<noreturn%> function does return", locus);
5285 /* If we see "return;" in some basic block, then we do reach the end
5286 without returning a value. */
5287 else if (warn_return_type
5288 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) > 0
5289 && !VOID_TYPE_P (TREE_TYPE (TREE_TYPE (cfun->decl))))
5291 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
5293 tree last = last_stmt (e->src);
5294 if (TREE_CODE (last) == RETURN_EXPR
5295 && TREE_OPERAND (last, 0) == NULL)
5297 #ifdef USE_MAPPED_LOCATION
5298 location = EXPR_LOCATION (last);
5299 if (location == UNKNOWN_LOCATION)
5300 location = cfun->function_end_locus;
5301 warning ("%Hcontrol reaches end of non-void function", &location);
5303 locus = EXPR_LOCUS (last);
5305 locus = &cfun->function_end_locus;
5306 warning ("%Hcontrol reaches end of non-void function", locus);
5315 /* Given a basic block B which ends with a conditional and has
5316 precisely two successors, determine which of the edges is taken if
5317 the conditional is true and which is taken if the conditional is
5318 false. Set TRUE_EDGE and FALSE_EDGE appropriately. */
5321 extract_true_false_edges_from_block (basic_block b,
5325 edge e = EDGE_SUCC (b, 0);
5327 if (e->flags & EDGE_TRUE_VALUE)
5330 *false_edge = EDGE_SUCC (b, 1);
5335 *true_edge = EDGE_SUCC (b, 1);
5339 struct tree_opt_pass pass_warn_function_return =
5343 execute_warn_function_return, /* execute */
5346 0, /* static_pass_number */
5348 PROP_cfg, /* properties_required */
5349 0, /* properties_provided */
5350 0, /* properties_destroyed */
5351 0, /* todo_flags_start */
5352 0, /* todo_flags_finish */
5356 #include "gt-tree-cfg.h"