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 it's 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 an undefined label. Emit a label to
611 the 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 ();
721 retval |= thread_jumps ();
723 #ifdef ENABLE_CHECKING
726 gcc_assert (!cleanup_control_flow ());
727 gcc_assert (!delete_unreachable_blocks ());
728 gcc_assert (!thread_jumps ());
732 /* Merging the blocks creates no new opportunities for the other
733 optimizations, so do it here. */
738 #ifdef ENABLE_CHECKING
741 timevar_pop (TV_TREE_CLEANUP_CFG);
746 /* Cleanup useless labels in basic blocks. This is something we wish
747 to do early because it allows us to group case labels before creating
748 the edges for the CFG, and it speeds up block statement iterators in
750 We only run this pass once, running it more than once is probably not
753 /* A map from basic block index to the leading label of that block. */
754 static tree *label_for_bb;
756 /* Callback for for_each_eh_region. Helper for cleanup_dead_labels. */
758 update_eh_label (struct eh_region *region)
760 tree old_label = get_eh_region_tree_label (region);
764 basic_block bb = label_to_block (old_label);
766 /* ??? After optimizing, there may be EH regions with labels
767 that have already been removed from the function body, so
768 there is no basic block for them. */
772 new_label = label_for_bb[bb->index];
773 set_eh_region_tree_label (region, new_label);
777 /* Given LABEL return the first label in the same basic block. */
779 main_block_label (tree label)
781 basic_block bb = label_to_block (label);
783 /* label_to_block possibly inserted undefined label into the chain. */
784 if (!label_for_bb[bb->index])
785 label_for_bb[bb->index] = label;
786 return label_for_bb[bb->index];
789 /* Cleanup redundant labels. This is a three-step process:
790 1) Find the leading label for each block.
791 2) Redirect all references to labels to the leading labels.
792 3) Cleanup all useless labels. */
795 cleanup_dead_labels (void)
798 label_for_bb = xcalloc (last_basic_block, sizeof (tree));
800 /* Find a suitable label for each block. We use the first user-defined
801 label if there is one, or otherwise just the first label we see. */
804 block_stmt_iterator i;
806 for (i = bsi_start (bb); !bsi_end_p (i); bsi_next (&i))
808 tree label, stmt = bsi_stmt (i);
810 if (TREE_CODE (stmt) != LABEL_EXPR)
813 label = LABEL_EXPR_LABEL (stmt);
815 /* If we have not yet seen a label for the current block,
816 remember this one and see if there are more labels. */
817 if (! label_for_bb[bb->index])
819 label_for_bb[bb->index] = label;
823 /* If we did see a label for the current block already, but it
824 is an artificially created label, replace it if the current
825 label is a user defined label. */
826 if (! DECL_ARTIFICIAL (label)
827 && DECL_ARTIFICIAL (label_for_bb[bb->index]))
829 label_for_bb[bb->index] = label;
835 /* Now redirect all jumps/branches to the selected label.
836 First do so for each block ending in a control statement. */
839 tree stmt = last_stmt (bb);
843 switch (TREE_CODE (stmt))
847 tree true_branch, false_branch;
849 true_branch = COND_EXPR_THEN (stmt);
850 false_branch = COND_EXPR_ELSE (stmt);
852 GOTO_DESTINATION (true_branch)
853 = main_block_label (GOTO_DESTINATION (true_branch));
854 GOTO_DESTINATION (false_branch)
855 = main_block_label (GOTO_DESTINATION (false_branch));
863 tree vec = SWITCH_LABELS (stmt);
864 size_t n = TREE_VEC_LENGTH (vec);
866 /* Replace all destination labels. */
867 for (i = 0; i < n; ++i)
868 CASE_LABEL (TREE_VEC_ELT (vec, i))
869 = main_block_label (CASE_LABEL (TREE_VEC_ELT (vec, i)));
874 /* We have to handle GOTO_EXPRs until they're removed, and we don't
875 remove them until after we've created the CFG edges. */
877 if (! computed_goto_p (stmt))
879 GOTO_DESTINATION (stmt)
880 = main_block_label (GOTO_DESTINATION (stmt));
889 for_each_eh_region (update_eh_label);
891 /* Finally, purge dead labels. All user-defined labels and labels that
892 can be the target of non-local gotos are preserved. */
895 block_stmt_iterator i;
896 tree label_for_this_bb = label_for_bb[bb->index];
898 if (! label_for_this_bb)
901 for (i = bsi_start (bb); !bsi_end_p (i); )
903 tree label, stmt = bsi_stmt (i);
905 if (TREE_CODE (stmt) != LABEL_EXPR)
908 label = LABEL_EXPR_LABEL (stmt);
910 if (label == label_for_this_bb
911 || ! DECL_ARTIFICIAL (label)
912 || DECL_NONLOCAL (label))
922 /* Look for blocks ending in a multiway branch (a SWITCH_EXPR in GIMPLE),
923 and scan the sorted vector of cases. Combine the ones jumping to the
925 Eg. three separate entries 1: 2: 3: become one entry 1..3: */
928 group_case_labels (void)
934 tree stmt = last_stmt (bb);
935 if (stmt && TREE_CODE (stmt) == SWITCH_EXPR)
937 tree labels = SWITCH_LABELS (stmt);
938 int old_size = TREE_VEC_LENGTH (labels);
939 int i, j, new_size = old_size;
940 tree default_case = TREE_VEC_ELT (labels, old_size - 1);
943 /* The default label is always the last case in a switch
944 statement after gimplification. */
945 default_label = CASE_LABEL (default_case);
947 /* Look for possible opportunities to merge cases.
948 Ignore the last element of the label vector because it
949 must be the default case. */
951 while (i < old_size - 1)
953 tree base_case, base_label, base_high, type;
954 base_case = TREE_VEC_ELT (labels, i);
956 gcc_assert (base_case);
957 base_label = CASE_LABEL (base_case);
959 /* Discard cases that have the same destination as the
961 if (base_label == default_label)
963 TREE_VEC_ELT (labels, i) = NULL_TREE;
969 type = TREE_TYPE (CASE_LOW (base_case));
970 base_high = CASE_HIGH (base_case) ?
971 CASE_HIGH (base_case) : CASE_LOW (base_case);
973 /* Try to merge case labels. Break out when we reach the end
974 of the label vector or when we cannot merge the next case
975 label with the current one. */
976 while (i < old_size - 1)
978 tree merge_case = TREE_VEC_ELT (labels, i);
979 tree merge_label = CASE_LABEL (merge_case);
980 tree t = int_const_binop (PLUS_EXPR, base_high,
981 integer_one_node, 1);
983 /* Merge the cases if they jump to the same place,
984 and their ranges are consecutive. */
985 if (merge_label == base_label
986 && tree_int_cst_equal (CASE_LOW (merge_case), t))
988 base_high = CASE_HIGH (merge_case) ?
989 CASE_HIGH (merge_case) : CASE_LOW (merge_case);
990 CASE_HIGH (base_case) = base_high;
991 TREE_VEC_ELT (labels, i) = NULL_TREE;
1000 /* Compress the case labels in the label vector, and adjust the
1001 length of the vector. */
1002 for (i = 0, j = 0; i < new_size; i++)
1004 while (! TREE_VEC_ELT (labels, j))
1006 TREE_VEC_ELT (labels, i) = TREE_VEC_ELT (labels, j++);
1008 TREE_VEC_LENGTH (labels) = new_size;
1013 /* Checks whether we can merge block B into block A. */
1016 tree_can_merge_blocks_p (basic_block a, basic_block b)
1019 block_stmt_iterator bsi;
1021 if (EDGE_COUNT (a->succs) != 1)
1024 if (EDGE_SUCC (a, 0)->flags & EDGE_ABNORMAL)
1027 if (EDGE_SUCC (a, 0)->dest != b)
1030 if (b == EXIT_BLOCK_PTR)
1033 if (EDGE_COUNT (b->preds) > 1)
1036 /* If A ends by a statement causing exceptions or something similar, we
1037 cannot merge the blocks. */
1038 stmt = last_stmt (a);
1039 if (stmt && stmt_ends_bb_p (stmt))
1042 /* Do not allow a block with only a non-local label to be merged. */
1043 if (stmt && TREE_CODE (stmt) == LABEL_EXPR
1044 && DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)))
1047 /* There may be no phi nodes at the start of b. Most of these degenerate
1048 phi nodes should be cleaned up by kill_redundant_phi_nodes. */
1052 /* Do not remove user labels. */
1053 for (bsi = bsi_start (b); !bsi_end_p (bsi); bsi_next (&bsi))
1055 stmt = bsi_stmt (bsi);
1056 if (TREE_CODE (stmt) != LABEL_EXPR)
1058 if (!DECL_ARTIFICIAL (LABEL_EXPR_LABEL (stmt)))
1066 /* Merge block B into block A. */
1069 tree_merge_blocks (basic_block a, basic_block b)
1071 block_stmt_iterator bsi;
1072 tree_stmt_iterator last;
1075 fprintf (dump_file, "Merging blocks %d and %d\n", a->index, b->index);
1077 /* Ensure that B follows A. */
1078 move_block_after (b, a);
1080 gcc_assert (EDGE_SUCC (a, 0)->flags & EDGE_FALLTHRU);
1081 gcc_assert (!last_stmt (a) || !stmt_ends_bb_p (last_stmt (a)));
1083 /* Remove labels from B and set bb_for_stmt to A for other statements. */
1084 for (bsi = bsi_start (b); !bsi_end_p (bsi);)
1086 if (TREE_CODE (bsi_stmt (bsi)) == LABEL_EXPR)
1090 set_bb_for_stmt (bsi_stmt (bsi), a);
1095 /* Merge the chains. */
1096 last = tsi_last (a->stmt_list);
1097 tsi_link_after (&last, b->stmt_list, TSI_NEW_STMT);
1098 b->stmt_list = NULL;
1102 /* Walk the function tree removing unnecessary statements.
1104 * Empty statement nodes are removed
1106 * Unnecessary TRY_FINALLY and TRY_CATCH blocks are removed
1108 * Unnecessary COND_EXPRs are removed
1110 * Some unnecessary BIND_EXPRs are removed
1112 Clearly more work could be done. The trick is doing the analysis
1113 and removal fast enough to be a net improvement in compile times.
1115 Note that when we remove a control structure such as a COND_EXPR
1116 BIND_EXPR, or TRY block, we will need to repeat this optimization pass
1117 to ensure we eliminate all the useless code. */
1128 static void remove_useless_stmts_1 (tree *, struct rus_data *);
1131 remove_useless_stmts_warn_notreached (tree stmt)
1133 if (EXPR_HAS_LOCATION (stmt))
1135 location_t loc = EXPR_LOCATION (stmt);
1136 warning ("%Hwill never be executed", &loc);
1140 switch (TREE_CODE (stmt))
1142 case STATEMENT_LIST:
1144 tree_stmt_iterator i;
1145 for (i = tsi_start (stmt); !tsi_end_p (i); tsi_next (&i))
1146 if (remove_useless_stmts_warn_notreached (tsi_stmt (i)))
1152 if (remove_useless_stmts_warn_notreached (COND_EXPR_COND (stmt)))
1154 if (remove_useless_stmts_warn_notreached (COND_EXPR_THEN (stmt)))
1156 if (remove_useless_stmts_warn_notreached (COND_EXPR_ELSE (stmt)))
1160 case TRY_FINALLY_EXPR:
1161 case TRY_CATCH_EXPR:
1162 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt, 0)))
1164 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt, 1)))
1169 return remove_useless_stmts_warn_notreached (CATCH_BODY (stmt));
1170 case EH_FILTER_EXPR:
1171 return remove_useless_stmts_warn_notreached (EH_FILTER_FAILURE (stmt));
1173 return remove_useless_stmts_warn_notreached (BIND_EXPR_BLOCK (stmt));
1176 /* Not a live container. */
1184 remove_useless_stmts_cond (tree *stmt_p, struct rus_data *data)
1186 tree then_clause, else_clause, cond;
1187 bool save_has_label, then_has_label, else_has_label;
1189 save_has_label = data->has_label;
1190 data->has_label = false;
1191 data->last_goto = NULL;
1193 remove_useless_stmts_1 (&COND_EXPR_THEN (*stmt_p), data);
1195 then_has_label = data->has_label;
1196 data->has_label = false;
1197 data->last_goto = NULL;
1199 remove_useless_stmts_1 (&COND_EXPR_ELSE (*stmt_p), data);
1201 else_has_label = data->has_label;
1202 data->has_label = save_has_label | then_has_label | else_has_label;
1205 then_clause = COND_EXPR_THEN (*stmt_p);
1206 else_clause = COND_EXPR_ELSE (*stmt_p);
1207 cond = COND_EXPR_COND (*stmt_p);
1209 /* If neither arm does anything at all, we can remove the whole IF. */
1210 if (!TREE_SIDE_EFFECTS (then_clause) && !TREE_SIDE_EFFECTS (else_clause))
1212 *stmt_p = build_empty_stmt ();
1213 data->repeat = true;
1216 /* If there are no reachable statements in an arm, then we can
1217 zap the entire conditional. */
1218 else if (integer_nonzerop (cond) && !else_has_label)
1220 if (warn_notreached)
1221 remove_useless_stmts_warn_notreached (else_clause);
1222 *stmt_p = then_clause;
1223 data->repeat = true;
1225 else if (integer_zerop (cond) && !then_has_label)
1227 if (warn_notreached)
1228 remove_useless_stmts_warn_notreached (then_clause);
1229 *stmt_p = else_clause;
1230 data->repeat = true;
1233 /* Check a couple of simple things on then/else with single stmts. */
1236 tree then_stmt = expr_only (then_clause);
1237 tree else_stmt = expr_only (else_clause);
1239 /* Notice branches to a common destination. */
1240 if (then_stmt && else_stmt
1241 && TREE_CODE (then_stmt) == GOTO_EXPR
1242 && TREE_CODE (else_stmt) == GOTO_EXPR
1243 && (GOTO_DESTINATION (then_stmt) == GOTO_DESTINATION (else_stmt)))
1245 *stmt_p = then_stmt;
1246 data->repeat = true;
1249 /* If the THEN/ELSE clause merely assigns a value to a variable or
1250 parameter which is already known to contain that value, then
1251 remove the useless THEN/ELSE clause. */
1252 else if (TREE_CODE (cond) == VAR_DECL || TREE_CODE (cond) == PARM_DECL)
1255 && TREE_CODE (else_stmt) == MODIFY_EXPR
1256 && TREE_OPERAND (else_stmt, 0) == cond
1257 && integer_zerop (TREE_OPERAND (else_stmt, 1)))
1258 COND_EXPR_ELSE (*stmt_p) = alloc_stmt_list ();
1260 else if ((TREE_CODE (cond) == EQ_EXPR || TREE_CODE (cond) == NE_EXPR)
1261 && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL
1262 || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL)
1263 && TREE_CONSTANT (TREE_OPERAND (cond, 1)))
1265 tree stmt = (TREE_CODE (cond) == EQ_EXPR
1266 ? then_stmt : else_stmt);
1267 tree *location = (TREE_CODE (cond) == EQ_EXPR
1268 ? &COND_EXPR_THEN (*stmt_p)
1269 : &COND_EXPR_ELSE (*stmt_p));
1272 && TREE_CODE (stmt) == MODIFY_EXPR
1273 && TREE_OPERAND (stmt, 0) == TREE_OPERAND (cond, 0)
1274 && TREE_OPERAND (stmt, 1) == TREE_OPERAND (cond, 1))
1275 *location = alloc_stmt_list ();
1279 /* Protect GOTOs in the arm of COND_EXPRs from being removed. They
1280 would be re-introduced during lowering. */
1281 data->last_goto = NULL;
1286 remove_useless_stmts_tf (tree *stmt_p, struct rus_data *data)
1288 bool save_may_branch, save_may_throw;
1289 bool this_may_branch, this_may_throw;
1291 /* Collect may_branch and may_throw information for the body only. */
1292 save_may_branch = data->may_branch;
1293 save_may_throw = data->may_throw;
1294 data->may_branch = false;
1295 data->may_throw = false;
1296 data->last_goto = NULL;
1298 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 0), data);
1300 this_may_branch = data->may_branch;
1301 this_may_throw = data->may_throw;
1302 data->may_branch |= save_may_branch;
1303 data->may_throw |= save_may_throw;
1304 data->last_goto = NULL;
1306 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 1), data);
1308 /* If the body is empty, then we can emit the FINALLY block without
1309 the enclosing TRY_FINALLY_EXPR. */
1310 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 0)))
1312 *stmt_p = TREE_OPERAND (*stmt_p, 1);
1313 data->repeat = true;
1316 /* If the handler is empty, then we can emit the TRY block without
1317 the enclosing TRY_FINALLY_EXPR. */
1318 else if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 1)))
1320 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1321 data->repeat = true;
1324 /* If the body neither throws, nor branches, then we can safely
1325 string the TRY and FINALLY blocks together. */
1326 else if (!this_may_branch && !this_may_throw)
1328 tree stmt = *stmt_p;
1329 *stmt_p = TREE_OPERAND (stmt, 0);
1330 append_to_statement_list (TREE_OPERAND (stmt, 1), stmt_p);
1331 data->repeat = true;
1337 remove_useless_stmts_tc (tree *stmt_p, struct rus_data *data)
1339 bool save_may_throw, this_may_throw;
1340 tree_stmt_iterator i;
1343 /* Collect may_throw information for the body only. */
1344 save_may_throw = data->may_throw;
1345 data->may_throw = false;
1346 data->last_goto = NULL;
1348 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 0), data);
1350 this_may_throw = data->may_throw;
1351 data->may_throw = save_may_throw;
1353 /* If the body cannot throw, then we can drop the entire TRY_CATCH_EXPR. */
1354 if (!this_may_throw)
1356 if (warn_notreached)
1357 remove_useless_stmts_warn_notreached (TREE_OPERAND (*stmt_p, 1));
1358 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1359 data->repeat = true;
1363 /* Process the catch clause specially. We may be able to tell that
1364 no exceptions propagate past this point. */
1366 this_may_throw = true;
1367 i = tsi_start (TREE_OPERAND (*stmt_p, 1));
1368 stmt = tsi_stmt (i);
1369 data->last_goto = NULL;
1371 switch (TREE_CODE (stmt))
1374 for (; !tsi_end_p (i); tsi_next (&i))
1376 stmt = tsi_stmt (i);
1377 /* If we catch all exceptions, then the body does not
1378 propagate exceptions past this point. */
1379 if (CATCH_TYPES (stmt) == NULL)
1380 this_may_throw = false;
1381 data->last_goto = NULL;
1382 remove_useless_stmts_1 (&CATCH_BODY (stmt), data);
1386 case EH_FILTER_EXPR:
1387 if (EH_FILTER_MUST_NOT_THROW (stmt))
1388 this_may_throw = false;
1389 else if (EH_FILTER_TYPES (stmt) == NULL)
1390 this_may_throw = false;
1391 remove_useless_stmts_1 (&EH_FILTER_FAILURE (stmt), data);
1395 /* Otherwise this is a cleanup. */
1396 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 1), data);
1398 /* If the cleanup is empty, then we can emit the TRY block without
1399 the enclosing TRY_CATCH_EXPR. */
1400 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 1)))
1402 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1403 data->repeat = true;
1407 data->may_throw |= this_may_throw;
1412 remove_useless_stmts_bind (tree *stmt_p, struct rus_data *data)
1416 /* First remove anything underneath the BIND_EXPR. */
1417 remove_useless_stmts_1 (&BIND_EXPR_BODY (*stmt_p), data);
1419 /* If the BIND_EXPR has no variables, then we can pull everything
1420 up one level and remove the BIND_EXPR, unless this is the toplevel
1421 BIND_EXPR for the current function or an inlined function.
1423 When this situation occurs we will want to apply this
1424 optimization again. */
1425 block = BIND_EXPR_BLOCK (*stmt_p);
1426 if (BIND_EXPR_VARS (*stmt_p) == NULL_TREE
1427 && *stmt_p != DECL_SAVED_TREE (current_function_decl)
1429 || ! BLOCK_ABSTRACT_ORIGIN (block)
1430 || (TREE_CODE (BLOCK_ABSTRACT_ORIGIN (block))
1433 *stmt_p = BIND_EXPR_BODY (*stmt_p);
1434 data->repeat = true;
1440 remove_useless_stmts_goto (tree *stmt_p, struct rus_data *data)
1442 tree dest = GOTO_DESTINATION (*stmt_p);
1444 data->may_branch = true;
1445 data->last_goto = NULL;
1447 /* Record the last goto expr, so that we can delete it if unnecessary. */
1448 if (TREE_CODE (dest) == LABEL_DECL)
1449 data->last_goto = stmt_p;
1454 remove_useless_stmts_label (tree *stmt_p, struct rus_data *data)
1456 tree label = LABEL_EXPR_LABEL (*stmt_p);
1458 data->has_label = true;
1460 /* We do want to jump across non-local label receiver code. */
1461 if (DECL_NONLOCAL (label))
1462 data->last_goto = NULL;
1464 else if (data->last_goto && GOTO_DESTINATION (*data->last_goto) == label)
1466 *data->last_goto = build_empty_stmt ();
1467 data->repeat = true;
1470 /* ??? Add something here to delete unused labels. */
1474 /* If the function is "const" or "pure", then clear TREE_SIDE_EFFECTS on its
1475 decl. This allows us to eliminate redundant or useless
1476 calls to "const" functions.
1478 Gimplifier already does the same operation, but we may notice functions
1479 being const and pure once their calls has been gimplified, so we need
1480 to update the flag. */
1483 update_call_expr_flags (tree call)
1485 tree decl = get_callee_fndecl (call);
1488 if (call_expr_flags (call) & (ECF_CONST | ECF_PURE))
1489 TREE_SIDE_EFFECTS (call) = 0;
1490 if (TREE_NOTHROW (decl))
1491 TREE_NOTHROW (call) = 1;
1495 /* T is CALL_EXPR. Set current_function_calls_* flags. */
1498 notice_special_calls (tree t)
1500 int flags = call_expr_flags (t);
1502 if (flags & ECF_MAY_BE_ALLOCA)
1503 current_function_calls_alloca = true;
1504 if (flags & ECF_RETURNS_TWICE)
1505 current_function_calls_setjmp = true;
1509 /* Clear flags set by notice_special_calls. Used by dead code removal
1510 to update the flags. */
1513 clear_special_calls (void)
1515 current_function_calls_alloca = false;
1516 current_function_calls_setjmp = false;
1521 remove_useless_stmts_1 (tree *tp, struct rus_data *data)
1525 switch (TREE_CODE (t))
1528 remove_useless_stmts_cond (tp, data);
1531 case TRY_FINALLY_EXPR:
1532 remove_useless_stmts_tf (tp, data);
1535 case TRY_CATCH_EXPR:
1536 remove_useless_stmts_tc (tp, data);
1540 remove_useless_stmts_bind (tp, data);
1544 remove_useless_stmts_goto (tp, data);
1548 remove_useless_stmts_label (tp, data);
1553 data->last_goto = NULL;
1554 data->may_branch = true;
1559 data->last_goto = NULL;
1560 notice_special_calls (t);
1561 update_call_expr_flags (t);
1562 if (tree_could_throw_p (t))
1563 data->may_throw = true;
1567 data->last_goto = NULL;
1569 op = get_call_expr_in (t);
1572 update_call_expr_flags (op);
1573 notice_special_calls (op);
1575 if (tree_could_throw_p (t))
1576 data->may_throw = true;
1579 case STATEMENT_LIST:
1581 tree_stmt_iterator i = tsi_start (t);
1582 while (!tsi_end_p (i))
1585 if (IS_EMPTY_STMT (t))
1591 remove_useless_stmts_1 (tsi_stmt_ptr (i), data);
1594 if (TREE_CODE (t) == STATEMENT_LIST)
1596 tsi_link_before (&i, t, TSI_SAME_STMT);
1606 data->last_goto = NULL;
1610 data->last_goto = NULL;
1616 remove_useless_stmts (void)
1618 struct rus_data data;
1620 clear_special_calls ();
1624 memset (&data, 0, sizeof (data));
1625 remove_useless_stmts_1 (&DECL_SAVED_TREE (current_function_decl), &data);
1627 while (data.repeat);
1631 struct tree_opt_pass pass_remove_useless_stmts =
1633 "useless", /* name */
1635 remove_useless_stmts, /* execute */
1638 0, /* static_pass_number */
1640 PROP_gimple_any, /* properties_required */
1641 0, /* properties_provided */
1642 0, /* properties_destroyed */
1643 0, /* todo_flags_start */
1644 TODO_dump_func, /* todo_flags_finish */
1649 /* Remove obviously useless statements in basic block BB. */
1652 cfg_remove_useless_stmts_bb (basic_block bb)
1654 block_stmt_iterator bsi;
1655 tree stmt = NULL_TREE;
1656 tree cond, var = NULL_TREE, val = NULL_TREE;
1657 struct var_ann_d *ann;
1659 /* Check whether we come here from a condition, and if so, get the
1661 if (EDGE_COUNT (bb->preds) != 1
1662 || !(EDGE_PRED (bb, 0)->flags & (EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
1665 cond = COND_EXPR_COND (last_stmt (EDGE_PRED (bb, 0)->src));
1667 if (TREE_CODE (cond) == VAR_DECL || TREE_CODE (cond) == PARM_DECL)
1670 val = (EDGE_PRED (bb, 0)->flags & EDGE_FALSE_VALUE
1671 ? boolean_false_node : boolean_true_node);
1673 else if (TREE_CODE (cond) == TRUTH_NOT_EXPR
1674 && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL
1675 || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL))
1677 var = TREE_OPERAND (cond, 0);
1678 val = (EDGE_PRED (bb, 0)->flags & EDGE_FALSE_VALUE
1679 ? boolean_true_node : boolean_false_node);
1683 if (EDGE_PRED (bb, 0)->flags & EDGE_FALSE_VALUE)
1684 cond = invert_truthvalue (cond);
1685 if (TREE_CODE (cond) == EQ_EXPR
1686 && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL
1687 || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL)
1688 && (TREE_CODE (TREE_OPERAND (cond, 1)) == VAR_DECL
1689 || TREE_CODE (TREE_OPERAND (cond, 1)) == PARM_DECL
1690 || TREE_CONSTANT (TREE_OPERAND (cond, 1))))
1692 var = TREE_OPERAND (cond, 0);
1693 val = TREE_OPERAND (cond, 1);
1699 /* Only work for normal local variables. */
1700 ann = var_ann (var);
1703 || TREE_ADDRESSABLE (var))
1706 if (! TREE_CONSTANT (val))
1708 ann = var_ann (val);
1711 || TREE_ADDRESSABLE (val))
1715 /* Ignore floating point variables, since comparison behaves weird for
1717 if (FLOAT_TYPE_P (TREE_TYPE (var)))
1720 for (bsi = bsi_start (bb); !bsi_end_p (bsi);)
1722 stmt = bsi_stmt (bsi);
1724 /* If the THEN/ELSE clause merely assigns a value to a variable/parameter
1725 which is already known to contain that value, then remove the useless
1726 THEN/ELSE clause. */
1727 if (TREE_CODE (stmt) == MODIFY_EXPR
1728 && TREE_OPERAND (stmt, 0) == var
1729 && operand_equal_p (val, TREE_OPERAND (stmt, 1), 0))
1735 /* Invalidate the var if we encounter something that could modify it.
1736 Likewise for the value it was previously set to. Note that we only
1737 consider values that are either a VAR_DECL or PARM_DECL so we
1738 can test for conflict very simply. */
1739 if (TREE_CODE (stmt) == ASM_EXPR
1740 || (TREE_CODE (stmt) == MODIFY_EXPR
1741 && (TREE_OPERAND (stmt, 0) == var
1742 || TREE_OPERAND (stmt, 0) == val)))
1750 /* A CFG-aware version of remove_useless_stmts. */
1753 cfg_remove_useless_stmts (void)
1757 #ifdef ENABLE_CHECKING
1758 verify_flow_info ();
1763 cfg_remove_useless_stmts_bb (bb);
1768 /* Remove PHI nodes associated with basic block BB and all edges out of BB. */
1771 remove_phi_nodes_and_edges_for_unreachable_block (basic_block bb)
1775 /* Since this block is no longer reachable, we can just delete all
1776 of its PHI nodes. */
1777 phi = phi_nodes (bb);
1780 tree next = PHI_CHAIN (phi);
1781 remove_phi_node (phi, NULL_TREE, bb);
1785 /* Remove edges to BB's successors. */
1786 while (EDGE_COUNT (bb->succs) > 0)
1787 ssa_remove_edge (EDGE_SUCC (bb, 0));
1791 /* Remove statements of basic block BB. */
1794 remove_bb (basic_block bb)
1796 block_stmt_iterator i;
1797 source_locus loc = 0;
1801 fprintf (dump_file, "Removing basic block %d\n", bb->index);
1802 if (dump_flags & TDF_DETAILS)
1804 dump_bb (bb, dump_file, 0);
1805 fprintf (dump_file, "\n");
1809 /* Remove all the instructions in the block. */
1810 for (i = bsi_start (bb); !bsi_end_p (i);)
1812 tree stmt = bsi_stmt (i);
1813 if (TREE_CODE (stmt) == LABEL_EXPR
1814 && FORCED_LABEL (LABEL_EXPR_LABEL (stmt)))
1816 basic_block new_bb = bb->prev_bb;
1817 block_stmt_iterator new_bsi = bsi_after_labels (new_bb);
1820 bsi_insert_after (&new_bsi, stmt, BSI_NEW_STMT);
1824 release_defs (stmt);
1826 set_bb_for_stmt (stmt, NULL);
1830 /* Don't warn for removed gotos. Gotos are often removed due to
1831 jump threading, thus resulting in bogus warnings. Not great,
1832 since this way we lose warnings for gotos in the original
1833 program that are indeed unreachable. */
1834 if (TREE_CODE (stmt) != GOTO_EXPR && EXPR_HAS_LOCATION (stmt) && !loc)
1835 #ifdef USE_MAPPED_LOCATION
1836 loc = EXPR_LOCATION (stmt);
1838 loc = EXPR_LOCUS (stmt);
1842 /* If requested, give a warning that the first statement in the
1843 block is unreachable. We walk statements backwards in the
1844 loop above, so the last statement we process is the first statement
1846 if (warn_notreached && loc)
1847 #ifdef USE_MAPPED_LOCATION
1848 warning ("%Hwill never be executed", &loc);
1850 warning ("%Hwill never be executed", loc);
1853 remove_phi_nodes_and_edges_for_unreachable_block (bb);
1856 /* Try to remove superfluous control structures. */
1859 cleanup_control_flow (void)
1862 block_stmt_iterator bsi;
1863 bool retval = false;
1868 bsi = bsi_last (bb);
1870 if (bsi_end_p (bsi))
1873 stmt = bsi_stmt (bsi);
1874 if (TREE_CODE (stmt) == COND_EXPR
1875 || TREE_CODE (stmt) == SWITCH_EXPR)
1876 retval |= cleanup_control_expr_graph (bb, bsi);
1882 /* Disconnect an unreachable block in the control expression starting
1886 cleanup_control_expr_graph (basic_block bb, block_stmt_iterator bsi)
1889 bool retval = false;
1890 tree expr = bsi_stmt (bsi), val;
1892 if (EDGE_COUNT (bb->succs) > 1)
1897 switch (TREE_CODE (expr))
1900 val = COND_EXPR_COND (expr);
1904 val = SWITCH_COND (expr);
1905 if (TREE_CODE (val) != INTEGER_CST)
1913 taken_edge = find_taken_edge (bb, val);
1917 /* Remove all the edges except the one that is always executed. */
1918 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
1920 if (e != taken_edge)
1922 taken_edge->probability += e->probability;
1923 taken_edge->count += e->count;
1924 ssa_remove_edge (e);
1930 if (taken_edge->probability > REG_BR_PROB_BASE)
1931 taken_edge->probability = REG_BR_PROB_BASE;
1934 taken_edge = EDGE_SUCC (bb, 0);
1937 taken_edge->flags = EDGE_FALLTHRU;
1939 /* We removed some paths from the cfg. */
1940 free_dominance_info (CDI_DOMINATORS);
1946 /* Given a control block BB and a predicate VAL, return the edge that
1947 will be taken out of the block. If VAL does not match a unique
1948 edge, NULL is returned. */
1951 find_taken_edge (basic_block bb, tree val)
1955 stmt = last_stmt (bb);
1958 gcc_assert (is_ctrl_stmt (stmt));
1960 /* If VAL is a predicate of the form N RELOP N, where N is an
1961 SSA_NAME, we can usually determine its truth value. */
1962 if (val && COMPARISON_CLASS_P (val))
1965 /* If VAL is not a constant, we can't determine which edge might
1967 if (val == NULL || !really_constant_p (val))
1970 if (TREE_CODE (stmt) == COND_EXPR)
1971 return find_taken_edge_cond_expr (bb, val);
1973 if (TREE_CODE (stmt) == SWITCH_EXPR)
1974 return find_taken_edge_switch_expr (bb, val);
1976 return EDGE_SUCC (bb, 0);
1980 /* Given a constant value VAL and the entry block BB to a COND_EXPR
1981 statement, determine which of the two edges will be taken out of the
1982 block. Return NULL if either edge may be taken. */
1985 find_taken_edge_cond_expr (basic_block bb, tree val)
1987 edge true_edge, false_edge;
1989 extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
1991 /* If both edges of the branch lead to the same basic block, it doesn't
1992 matter which edge is taken. */
1993 if (true_edge->dest == false_edge->dest)
1996 /* Otherwise, try to determine which branch of the if() will be taken.
1997 If VAL is a constant but it can't be reduced to a 0 or a 1, then
1998 we don't really know which edge will be taken at runtime. This
1999 may happen when comparing addresses (e.g., if (&var1 == 4)). */
2000 if (integer_nonzerop (val))
2002 else if (integer_zerop (val))
2009 /* Given a constant value VAL and the entry block BB to a SWITCH_EXPR
2010 statement, determine which edge will be taken out of the block. Return
2011 NULL if any edge may be taken. */
2014 find_taken_edge_switch_expr (basic_block bb, tree val)
2016 tree switch_expr, taken_case;
2017 basic_block dest_bb;
2020 if (TREE_CODE (val) != INTEGER_CST)
2023 switch_expr = last_stmt (bb);
2024 taken_case = find_case_label_for_value (switch_expr, val);
2025 dest_bb = label_to_block (CASE_LABEL (taken_case));
2027 e = find_edge (bb, dest_bb);
2033 /* Return the CASE_LABEL_EXPR that SWITCH_EXPR will take for VAL.
2034 We can make optimal use here of the fact that the case labels are
2035 sorted: We can do a binary search for a case matching VAL. */
2038 find_case_label_for_value (tree switch_expr, tree val)
2040 tree vec = SWITCH_LABELS (switch_expr);
2041 size_t low, high, n = TREE_VEC_LENGTH (vec);
2042 tree default_case = TREE_VEC_ELT (vec, n - 1);
2044 for (low = -1, high = n - 1; high - low > 1; )
2046 size_t i = (high + low) / 2;
2047 tree t = TREE_VEC_ELT (vec, i);
2050 /* Cache the result of comparing CASE_LOW and val. */
2051 cmp = tree_int_cst_compare (CASE_LOW (t), val);
2058 if (CASE_HIGH (t) == NULL)
2060 /* A singe-valued case label. */
2066 /* A case range. We can only handle integer ranges. */
2067 if (cmp <= 0 && tree_int_cst_compare (CASE_HIGH (t), val) >= 0)
2072 return default_case;
2076 /* If all the PHI nodes in DEST have alternatives for E1 and E2 and
2077 those alternatives are equal in each of the PHI nodes, then return
2078 true, else return false. */
2081 phi_alternatives_equal (basic_block dest, edge e1, edge e2)
2083 tree phi, val1, val2;
2086 for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi))
2088 n1 = phi_arg_from_edge (phi, e1);
2089 n2 = phi_arg_from_edge (phi, e2);
2091 gcc_assert (n1 >= 0);
2092 gcc_assert (n2 >= 0);
2094 val1 = PHI_ARG_DEF (phi, n1);
2095 val2 = PHI_ARG_DEF (phi, n2);
2097 if (!operand_equal_p (val1, val2, 0))
2105 /*---------------------------------------------------------------------------
2107 ---------------------------------------------------------------------------*/
2109 /* Dump tree-specific information of block BB to file OUTF. */
2112 tree_dump_bb (basic_block bb, FILE *outf, int indent)
2114 dump_generic_bb (outf, bb, indent, TDF_VOPS);
2118 /* Dump a basic block on stderr. */
2121 debug_tree_bb (basic_block bb)
2123 dump_bb (bb, stderr, 0);
2127 /* Dump basic block with index N on stderr. */
2130 debug_tree_bb_n (int n)
2132 debug_tree_bb (BASIC_BLOCK (n));
2133 return BASIC_BLOCK (n);
2137 /* Dump the CFG on stderr.
2139 FLAGS are the same used by the tree dumping functions
2140 (see TDF_* in tree.h). */
2143 debug_tree_cfg (int flags)
2145 dump_tree_cfg (stderr, flags);
2149 /* Dump the program showing basic block boundaries on the given FILE.
2151 FLAGS are the same used by the tree dumping functions (see TDF_* in
2155 dump_tree_cfg (FILE *file, int flags)
2157 if (flags & TDF_DETAILS)
2159 const char *funcname
2160 = lang_hooks.decl_printable_name (current_function_decl, 2);
2163 fprintf (file, ";; Function %s\n\n", funcname);
2164 fprintf (file, ";; \n%d basic blocks, %d edges, last basic block %d.\n\n",
2165 n_basic_blocks, n_edges, last_basic_block);
2167 brief_dump_cfg (file);
2168 fprintf (file, "\n");
2171 if (flags & TDF_STATS)
2172 dump_cfg_stats (file);
2174 dump_function_to_file (current_function_decl, file, flags | TDF_BLOCKS);
2178 /* Dump CFG statistics on FILE. */
2181 dump_cfg_stats (FILE *file)
2183 static long max_num_merged_labels = 0;
2184 unsigned long size, total = 0;
2187 const char * const fmt_str = "%-30s%-13s%12s\n";
2188 const char * const fmt_str_1 = "%-30s%13d%11lu%c\n";
2189 const char * const fmt_str_3 = "%-43s%11lu%c\n";
2190 const char *funcname
2191 = lang_hooks.decl_printable_name (current_function_decl, 2);
2194 fprintf (file, "\nCFG Statistics for %s\n\n", funcname);
2196 fprintf (file, "---------------------------------------------------------\n");
2197 fprintf (file, fmt_str, "", " Number of ", "Memory");
2198 fprintf (file, fmt_str, "", " instances ", "used ");
2199 fprintf (file, "---------------------------------------------------------\n");
2201 size = n_basic_blocks * sizeof (struct basic_block_def);
2203 fprintf (file, fmt_str_1, "Basic blocks", n_basic_blocks,
2204 SCALE (size), LABEL (size));
2208 n_edges += EDGE_COUNT (bb->succs);
2209 size = n_edges * sizeof (struct edge_def);
2211 fprintf (file, fmt_str_1, "Edges", n_edges, SCALE (size), LABEL (size));
2213 size = n_basic_blocks * sizeof (struct bb_ann_d);
2215 fprintf (file, fmt_str_1, "Basic block annotations", n_basic_blocks,
2216 SCALE (size), LABEL (size));
2218 fprintf (file, "---------------------------------------------------------\n");
2219 fprintf (file, fmt_str_3, "Total memory used by CFG data", SCALE (total),
2221 fprintf (file, "---------------------------------------------------------\n");
2222 fprintf (file, "\n");
2224 if (cfg_stats.num_merged_labels > max_num_merged_labels)
2225 max_num_merged_labels = cfg_stats.num_merged_labels;
2227 fprintf (file, "Coalesced label blocks: %ld (Max so far: %ld)\n",
2228 cfg_stats.num_merged_labels, max_num_merged_labels);
2230 fprintf (file, "\n");
2234 /* Dump CFG statistics on stderr. Keep extern so that it's always
2235 linked in the final executable. */
2238 debug_cfg_stats (void)
2240 dump_cfg_stats (stderr);
2244 /* Dump the flowgraph to a .vcg FILE. */
2247 tree_cfg2vcg (FILE *file)
2252 const char *funcname
2253 = lang_hooks.decl_printable_name (current_function_decl, 2);
2255 /* Write the file header. */
2256 fprintf (file, "graph: { title: \"%s\"\n", funcname);
2257 fprintf (file, "node: { title: \"ENTRY\" label: \"ENTRY\" }\n");
2258 fprintf (file, "node: { title: \"EXIT\" label: \"EXIT\" }\n");
2260 /* Write blocks and edges. */
2261 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
2263 fprintf (file, "edge: { sourcename: \"ENTRY\" targetname: \"%d\"",
2266 if (e->flags & EDGE_FAKE)
2267 fprintf (file, " linestyle: dotted priority: 10");
2269 fprintf (file, " linestyle: solid priority: 100");
2271 fprintf (file, " }\n");
2277 enum tree_code head_code, end_code;
2278 const char *head_name, *end_name;
2281 tree first = first_stmt (bb);
2282 tree last = last_stmt (bb);
2286 head_code = TREE_CODE (first);
2287 head_name = tree_code_name[head_code];
2288 head_line = get_lineno (first);
2291 head_name = "no-statement";
2295 end_code = TREE_CODE (last);
2296 end_name = tree_code_name[end_code];
2297 end_line = get_lineno (last);
2300 end_name = "no-statement";
2302 fprintf (file, "node: { title: \"%d\" label: \"#%d\\n%s (%d)\\n%s (%d)\"}\n",
2303 bb->index, bb->index, head_name, head_line, end_name,
2306 FOR_EACH_EDGE (e, ei, bb->succs)
2308 if (e->dest == EXIT_BLOCK_PTR)
2309 fprintf (file, "edge: { sourcename: \"%d\" targetname: \"EXIT\"", bb->index);
2311 fprintf (file, "edge: { sourcename: \"%d\" targetname: \"%d\"", bb->index, e->dest->index);
2313 if (e->flags & EDGE_FAKE)
2314 fprintf (file, " priority: 10 linestyle: dotted");
2316 fprintf (file, " priority: 100 linestyle: solid");
2318 fprintf (file, " }\n");
2321 if (bb->next_bb != EXIT_BLOCK_PTR)
2325 fputs ("}\n\n", file);
2330 /*---------------------------------------------------------------------------
2331 Miscellaneous helpers
2332 ---------------------------------------------------------------------------*/
2334 /* Return true if T represents a stmt that always transfers control. */
2337 is_ctrl_stmt (tree t)
2339 return (TREE_CODE (t) == COND_EXPR
2340 || TREE_CODE (t) == SWITCH_EXPR
2341 || TREE_CODE (t) == GOTO_EXPR
2342 || TREE_CODE (t) == RETURN_EXPR
2343 || TREE_CODE (t) == RESX_EXPR);
2347 /* Return true if T is a statement that may alter the flow of control
2348 (e.g., a call to a non-returning function). */
2351 is_ctrl_altering_stmt (tree t)
2356 call = get_call_expr_in (t);
2359 /* A non-pure/const CALL_EXPR alters flow control if the current
2360 function has nonlocal labels. */
2361 if (TREE_SIDE_EFFECTS (call) && current_function_has_nonlocal_label)
2364 /* A CALL_EXPR also alters control flow if it does not return. */
2365 if (call_expr_flags (call) & (ECF_NORETURN | ECF_LONGJMP))
2369 /* If a statement can throw, it alters control flow. */
2370 return tree_can_throw_internal (t);
2374 /* Return true if T is a computed goto. */
2377 computed_goto_p (tree t)
2379 return (TREE_CODE (t) == GOTO_EXPR
2380 && TREE_CODE (GOTO_DESTINATION (t)) != LABEL_DECL);
2384 /* Checks whether EXPR is a simple local goto. */
2387 simple_goto_p (tree expr)
2389 return (TREE_CODE (expr) == GOTO_EXPR
2390 && TREE_CODE (GOTO_DESTINATION (expr)) == LABEL_DECL);
2394 /* Return true if T should start a new basic block. PREV_T is the
2395 statement preceding T. It is used when T is a label or a case label.
2396 Labels should only start a new basic block if their previous statement
2397 wasn't a label. Otherwise, sequence of labels would generate
2398 unnecessary basic blocks that only contain a single label. */
2401 stmt_starts_bb_p (tree t, tree prev_t)
2403 enum tree_code code;
2408 /* LABEL_EXPRs start a new basic block only if the preceding
2409 statement wasn't a label of the same type. This prevents the
2410 creation of consecutive blocks that have nothing but a single
2412 code = TREE_CODE (t);
2413 if (code == LABEL_EXPR)
2415 /* Nonlocal and computed GOTO targets always start a new block. */
2416 if (code == LABEL_EXPR
2417 && (DECL_NONLOCAL (LABEL_EXPR_LABEL (t))
2418 || FORCED_LABEL (LABEL_EXPR_LABEL (t))))
2421 if (prev_t && TREE_CODE (prev_t) == code)
2423 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (prev_t)))
2426 cfg_stats.num_merged_labels++;
2437 /* Return true if T should end a basic block. */
2440 stmt_ends_bb_p (tree t)
2442 return is_ctrl_stmt (t) || is_ctrl_altering_stmt (t);
2446 /* Add gotos that used to be represented implicitly in the CFG. */
2449 disband_implicit_edges (void)
2452 block_stmt_iterator last;
2459 last = bsi_last (bb);
2460 stmt = last_stmt (bb);
2462 if (stmt && TREE_CODE (stmt) == COND_EXPR)
2464 /* Remove superfluous gotos from COND_EXPR branches. Moved
2465 from cfg_remove_useless_stmts here since it violates the
2466 invariants for tree--cfg correspondence and thus fits better
2467 here where we do it anyway. */
2468 FOR_EACH_EDGE (e, ei, bb->succs)
2470 if (e->dest != bb->next_bb)
2473 if (e->flags & EDGE_TRUE_VALUE)
2474 COND_EXPR_THEN (stmt) = build_empty_stmt ();
2475 else if (e->flags & EDGE_FALSE_VALUE)
2476 COND_EXPR_ELSE (stmt) = build_empty_stmt ();
2479 e->flags |= EDGE_FALLTHRU;
2485 if (stmt && TREE_CODE (stmt) == RETURN_EXPR)
2487 /* Remove the RETURN_EXPR if we may fall though to the exit
2489 gcc_assert (EDGE_COUNT (bb->succs) == 1);
2490 gcc_assert (EDGE_SUCC (bb, 0)->dest == EXIT_BLOCK_PTR);
2492 if (bb->next_bb == EXIT_BLOCK_PTR
2493 && !TREE_OPERAND (stmt, 0))
2496 EDGE_SUCC (bb, 0)->flags |= EDGE_FALLTHRU;
2501 /* There can be no fallthru edge if the last statement is a control
2503 if (stmt && is_ctrl_stmt (stmt))
2506 /* Find a fallthru edge and emit the goto if necessary. */
2507 FOR_EACH_EDGE (e, ei, bb->succs)
2508 if (e->flags & EDGE_FALLTHRU)
2511 if (!e || e->dest == bb->next_bb)
2514 gcc_assert (e->dest != EXIT_BLOCK_PTR);
2515 label = tree_block_label (e->dest);
2517 stmt = build1 (GOTO_EXPR, void_type_node, label);
2518 #ifdef USE_MAPPED_LOCATION
2519 SET_EXPR_LOCATION (stmt, e->goto_locus);
2521 SET_EXPR_LOCUS (stmt, e->goto_locus);
2523 bsi_insert_after (&last, stmt, BSI_NEW_STMT);
2524 e->flags &= ~EDGE_FALLTHRU;
2528 /* Remove block annotations and other datastructures. */
2531 delete_tree_cfg_annotations (void)
2534 if (n_basic_blocks > 0)
2535 free_blocks_annotations ();
2537 label_to_block_map = NULL;
2544 /* Return the first statement in basic block BB. */
2547 first_stmt (basic_block bb)
2549 block_stmt_iterator i = bsi_start (bb);
2550 return !bsi_end_p (i) ? bsi_stmt (i) : NULL_TREE;
2554 /* Return the last statement in basic block BB. */
2557 last_stmt (basic_block bb)
2559 block_stmt_iterator b = bsi_last (bb);
2560 return !bsi_end_p (b) ? bsi_stmt (b) : NULL_TREE;
2564 /* Return a pointer to the last statement in block BB. */
2567 last_stmt_ptr (basic_block bb)
2569 block_stmt_iterator last = bsi_last (bb);
2570 return !bsi_end_p (last) ? bsi_stmt_ptr (last) : NULL;
2574 /* Return the last statement of an otherwise empty block. Return NULL
2575 if the block is totally empty, or if it contains more than one
2579 last_and_only_stmt (basic_block bb)
2581 block_stmt_iterator i = bsi_last (bb);
2587 last = bsi_stmt (i);
2592 /* Empty statements should no longer appear in the instruction stream.
2593 Everything that might have appeared before should be deleted by
2594 remove_useless_stmts, and the optimizers should just bsi_remove
2595 instead of smashing with build_empty_stmt.
2597 Thus the only thing that should appear here in a block containing
2598 one executable statement is a label. */
2599 prev = bsi_stmt (i);
2600 if (TREE_CODE (prev) == LABEL_EXPR)
2607 /* Mark BB as the basic block holding statement T. */
2610 set_bb_for_stmt (tree t, basic_block bb)
2612 if (TREE_CODE (t) == PHI_NODE)
2614 else if (TREE_CODE (t) == STATEMENT_LIST)
2616 tree_stmt_iterator i;
2617 for (i = tsi_start (t); !tsi_end_p (i); tsi_next (&i))
2618 set_bb_for_stmt (tsi_stmt (i), bb);
2622 stmt_ann_t ann = get_stmt_ann (t);
2625 /* If the statement is a label, add the label to block-to-labels map
2626 so that we can speed up edge creation for GOTO_EXPRs. */
2627 if (TREE_CODE (t) == LABEL_EXPR)
2631 t = LABEL_EXPR_LABEL (t);
2632 uid = LABEL_DECL_UID (t);
2635 LABEL_DECL_UID (t) = uid = cfun->last_label_uid++;
2636 if (VARRAY_SIZE (label_to_block_map) <= (unsigned) uid)
2637 VARRAY_GROW (label_to_block_map, 3 * uid / 2);
2640 /* We're moving an existing label. Make sure that we've
2641 removed it from the old block. */
2642 gcc_assert (!bb || !VARRAY_BB (label_to_block_map, uid));
2643 VARRAY_BB (label_to_block_map, uid) = bb;
2648 /* Finds iterator for STMT. */
2650 extern block_stmt_iterator
2651 bsi_for_stmt (tree stmt)
2653 block_stmt_iterator bsi;
2655 for (bsi = bsi_start (bb_for_stmt (stmt)); !bsi_end_p (bsi); bsi_next (&bsi))
2656 if (bsi_stmt (bsi) == stmt)
2662 /* Insert statement (or statement list) T before the statement
2663 pointed-to by iterator I. M specifies how to update iterator I
2664 after insertion (see enum bsi_iterator_update). */
2667 bsi_insert_before (block_stmt_iterator *i, tree t, enum bsi_iterator_update m)
2669 set_bb_for_stmt (t, i->bb);
2670 tsi_link_before (&i->tsi, t, m);
2675 /* Insert statement (or statement list) T after the statement
2676 pointed-to by iterator I. M specifies how to update iterator I
2677 after insertion (see enum bsi_iterator_update). */
2680 bsi_insert_after (block_stmt_iterator *i, tree t, enum bsi_iterator_update m)
2682 set_bb_for_stmt (t, i->bb);
2683 tsi_link_after (&i->tsi, t, m);
2688 /* Remove the statement pointed to by iterator I. The iterator is updated
2689 to the next statement. */
2692 bsi_remove (block_stmt_iterator *i)
2694 tree t = bsi_stmt (*i);
2695 set_bb_for_stmt (t, NULL);
2696 tsi_delink (&i->tsi);
2700 /* Move the statement at FROM so it comes right after the statement at TO. */
2703 bsi_move_after (block_stmt_iterator *from, block_stmt_iterator *to)
2705 tree stmt = bsi_stmt (*from);
2707 bsi_insert_after (to, stmt, BSI_SAME_STMT);
2711 /* Move the statement at FROM so it comes right before the statement at TO. */
2714 bsi_move_before (block_stmt_iterator *from, block_stmt_iterator *to)
2716 tree stmt = bsi_stmt (*from);
2718 bsi_insert_before (to, stmt, BSI_SAME_STMT);
2722 /* Move the statement at FROM to the end of basic block BB. */
2725 bsi_move_to_bb_end (block_stmt_iterator *from, basic_block bb)
2727 block_stmt_iterator last = bsi_last (bb);
2729 /* Have to check bsi_end_p because it could be an empty block. */
2730 if (!bsi_end_p (last) && is_ctrl_stmt (bsi_stmt (last)))
2731 bsi_move_before (from, &last);
2733 bsi_move_after (from, &last);
2737 /* Replace the contents of the statement pointed to by iterator BSI
2738 with STMT. If PRESERVE_EH_INFO is true, the exception handling
2739 information of the original statement is preserved. */
2742 bsi_replace (const block_stmt_iterator *bsi, tree stmt, bool preserve_eh_info)
2745 tree orig_stmt = bsi_stmt (*bsi);
2747 SET_EXPR_LOCUS (stmt, EXPR_LOCUS (orig_stmt));
2748 set_bb_for_stmt (stmt, bsi->bb);
2750 /* Preserve EH region information from the original statement, if
2751 requested by the caller. */
2752 if (preserve_eh_info)
2754 eh_region = lookup_stmt_eh_region (orig_stmt);
2756 add_stmt_to_eh_region (stmt, eh_region);
2759 *bsi_stmt_ptr (*bsi) = stmt;
2764 /* Insert the statement pointed-to by BSI into edge E. Every attempt
2765 is made to place the statement in an existing basic block, but
2766 sometimes that isn't possible. When it isn't possible, the edge is
2767 split and the statement is added to the new block.
2769 In all cases, the returned *BSI points to the correct location. The
2770 return value is true if insertion should be done after the location,
2771 or false if it should be done before the location. If new basic block
2772 has to be created, it is stored in *NEW_BB. */
2775 tree_find_edge_insert_loc (edge e, block_stmt_iterator *bsi,
2776 basic_block *new_bb)
2778 basic_block dest, src;
2784 /* If the destination has one predecessor which has no PHI nodes,
2785 insert there. Except for the exit block.
2787 The requirement for no PHI nodes could be relaxed. Basically we
2788 would have to examine the PHIs to prove that none of them used
2789 the value set by the statement we want to insert on E. That
2790 hardly seems worth the effort. */
2791 if (EDGE_COUNT (dest->preds) == 1
2792 && ! phi_nodes (dest)
2793 && dest != EXIT_BLOCK_PTR)
2795 *bsi = bsi_start (dest);
2796 if (bsi_end_p (*bsi))
2799 /* Make sure we insert after any leading labels. */
2800 tmp = bsi_stmt (*bsi);
2801 while (TREE_CODE (tmp) == LABEL_EXPR)
2804 if (bsi_end_p (*bsi))
2806 tmp = bsi_stmt (*bsi);
2809 if (bsi_end_p (*bsi))
2811 *bsi = bsi_last (dest);
2818 /* If the source has one successor, the edge is not abnormal and
2819 the last statement does not end a basic block, insert there.
2820 Except for the entry block. */
2822 if ((e->flags & EDGE_ABNORMAL) == 0
2823 && EDGE_COUNT (src->succs) == 1
2824 && src != ENTRY_BLOCK_PTR)
2826 *bsi = bsi_last (src);
2827 if (bsi_end_p (*bsi))
2830 tmp = bsi_stmt (*bsi);
2831 if (!stmt_ends_bb_p (tmp))
2834 /* Insert code just before returning the value. We may need to decompose
2835 the return in the case it contains non-trivial operand. */
2836 if (TREE_CODE (tmp) == RETURN_EXPR)
2838 tree op = TREE_OPERAND (tmp, 0);
2839 if (!is_gimple_val (op))
2841 gcc_assert (TREE_CODE (op) == MODIFY_EXPR);
2842 bsi_insert_before (bsi, op, BSI_NEW_STMT);
2843 TREE_OPERAND (tmp, 0) = TREE_OPERAND (op, 0);
2850 /* Otherwise, create a new basic block, and split this edge. */
2851 dest = split_edge (e);
2854 e = EDGE_PRED (dest, 0);
2859 /* This routine will commit all pending edge insertions, creating any new
2860 basic blocks which are necessary.
2862 If specified, NEW_BLOCKS returns a count of the number of new basic
2863 blocks which were created. */
2866 bsi_commit_edge_inserts (int *new_blocks)
2873 blocks = n_basic_blocks;
2875 bsi_commit_edge_inserts_1 (EDGE_SUCC (ENTRY_BLOCK_PTR, 0));
2878 FOR_EACH_EDGE (e, ei, bb->succs)
2879 bsi_commit_edge_inserts_1 (e);
2882 *new_blocks = n_basic_blocks - blocks;
2886 /* Commit insertions pending at edge E. */
2889 bsi_commit_edge_inserts_1 (edge e)
2891 if (PENDING_STMT (e))
2893 block_stmt_iterator bsi;
2894 tree stmt = PENDING_STMT (e);
2896 PENDING_STMT (e) = NULL_TREE;
2898 if (tree_find_edge_insert_loc (e, &bsi, NULL))
2899 bsi_insert_after (&bsi, stmt, BSI_NEW_STMT);
2901 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
2906 /* Add STMT to the pending list of edge E. No actual insertion is
2907 made until a call to bsi_commit_edge_inserts () is made. */
2910 bsi_insert_on_edge (edge e, tree stmt)
2912 append_to_statement_list (stmt, &PENDING_STMT (e));
2915 /* Similar to bsi_insert_on_edge+bsi_commit_edge_inserts. If new block has to
2916 be created, it is returned. */
2919 bsi_insert_on_edge_immediate (edge e, tree stmt)
2921 block_stmt_iterator bsi;
2922 basic_block new_bb = NULL;
2924 gcc_assert (!PENDING_STMT (e));
2926 if (tree_find_edge_insert_loc (e, &bsi, &new_bb))
2927 bsi_insert_after (&bsi, stmt, BSI_NEW_STMT);
2929 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
2934 /*---------------------------------------------------------------------------
2935 Tree specific functions for CFG manipulation
2936 ---------------------------------------------------------------------------*/
2938 /* Split a (typically critical) edge EDGE_IN. Return the new block.
2939 Abort on abnormal edges. */
2942 tree_split_edge (edge edge_in)
2944 basic_block new_bb, after_bb, dest, src;
2950 /* Abnormal edges cannot be split. */
2951 gcc_assert (!(edge_in->flags & EDGE_ABNORMAL));
2954 dest = edge_in->dest;
2956 /* Place the new block in the block list. Try to keep the new block
2957 near its "logical" location. This is of most help to humans looking
2958 at debugging dumps. */
2959 FOR_EACH_EDGE (e, ei, dest->preds)
2960 if (e->src->next_bb == dest)
2963 after_bb = dest->prev_bb;
2965 after_bb = edge_in->src;
2967 new_bb = create_empty_bb (after_bb);
2968 new_bb->frequency = EDGE_FREQUENCY (edge_in);
2969 new_bb->count = edge_in->count;
2970 new_edge = make_edge (new_bb, dest, EDGE_FALLTHRU);
2971 new_edge->probability = REG_BR_PROB_BASE;
2972 new_edge->count = edge_in->count;
2974 /* Find all the PHI arguments on the original edge, and change them to
2975 the new edge. Do it before redirection, so that the argument does not
2977 for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi))
2979 num_elem = PHI_NUM_ARGS (phi);
2980 for (i = 0; i < num_elem; i++)
2981 if (PHI_ARG_EDGE (phi, i) == edge_in)
2983 PHI_ARG_EDGE (phi, i) = new_edge;
2988 e = redirect_edge_and_branch (edge_in, new_bb);
2990 gcc_assert (!PENDING_STMT (edge_in));
2996 /* Return true when BB has label LABEL in it. */
2999 has_label_p (basic_block bb, tree label)
3001 block_stmt_iterator bsi;
3003 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3005 tree stmt = bsi_stmt (bsi);
3007 if (TREE_CODE (stmt) != LABEL_EXPR)
3009 if (LABEL_EXPR_LABEL (stmt) == label)
3016 /* Callback for walk_tree, check that all elements with address taken are
3017 properly noticed as such. */
3020 verify_expr (tree *tp, int *walk_subtrees, void *data ATTRIBUTE_UNUSED)
3027 /* Check operand N for being valid GIMPLE and give error MSG if not.
3028 We check for constants explicitly since they are not considered
3029 gimple invariants if they overflowed. */
3030 #define CHECK_OP(N, MSG) \
3031 do { if (!CONSTANT_CLASS_P (TREE_OPERAND (t, N)) \
3032 && !is_gimple_val (TREE_OPERAND (t, N))) \
3033 { error (MSG); return TREE_OPERAND (t, N); }} while (0)
3035 switch (TREE_CODE (t))
3038 if (SSA_NAME_IN_FREE_LIST (t))
3040 error ("SSA name in freelist but still referenced");
3046 x = TREE_OPERAND (t, 0);
3047 if (TREE_CODE (x) == BIT_FIELD_REF
3048 && is_gimple_reg (TREE_OPERAND (x, 0)))
3050 error ("GIMPLE register modified with BIT_FIELD_REF");
3056 /* Skip any references (they will be checked when we recurse down the
3057 tree) and ensure that any variable used as a prefix is marked
3059 for (x = TREE_OPERAND (t, 0);
3060 (handled_component_p (x)
3061 || TREE_CODE (x) == REALPART_EXPR
3062 || TREE_CODE (x) == IMAGPART_EXPR);
3063 x = TREE_OPERAND (x, 0))
3066 if (TREE_CODE (x) != VAR_DECL && TREE_CODE (x) != PARM_DECL)
3068 if (!TREE_ADDRESSABLE (x))
3070 error ("address taken, but ADDRESSABLE bit not set");
3076 x = TREE_OPERAND (t, 0);
3077 if (TREE_CODE (TREE_TYPE (x)) != BOOLEAN_TYPE)
3079 error ("non-boolean used in condition");
3086 case FIX_TRUNC_EXPR:
3088 case FIX_FLOOR_EXPR:
3089 case FIX_ROUND_EXPR:
3094 case NON_LVALUE_EXPR:
3095 case TRUTH_NOT_EXPR:
3096 CHECK_OP (0, "Invalid operand to unary operator");
3103 case ARRAY_RANGE_REF:
3105 case VIEW_CONVERT_EXPR:
3106 /* We have a nest of references. Verify that each of the operands
3107 that determine where to reference is either a constant or a variable,
3108 verify that the base is valid, and then show we've already checked
3110 while (TREE_CODE (t) == REALPART_EXPR || TREE_CODE (t) == IMAGPART_EXPR
3111 || handled_component_p (t))
3113 if (TREE_CODE (t) == COMPONENT_REF && TREE_OPERAND (t, 2))
3114 CHECK_OP (2, "Invalid COMPONENT_REF offset operator");
3115 else if (TREE_CODE (t) == ARRAY_REF
3116 || TREE_CODE (t) == ARRAY_RANGE_REF)
3118 CHECK_OP (1, "Invalid array index.");
3119 if (TREE_OPERAND (t, 2))
3120 CHECK_OP (2, "Invalid array lower bound.");
3121 if (TREE_OPERAND (t, 3))
3122 CHECK_OP (3, "Invalid array stride.");
3124 else if (TREE_CODE (t) == BIT_FIELD_REF)
3126 CHECK_OP (1, "Invalid operand to BIT_FIELD_REF");
3127 CHECK_OP (2, "Invalid operand to BIT_FIELD_REF");
3130 t = TREE_OPERAND (t, 0);
3133 if (!CONSTANT_CLASS_P (t) && !is_gimple_lvalue (t))
3135 error ("Invalid reference prefix.");
3147 case UNORDERED_EXPR:
3158 case TRUNC_DIV_EXPR:
3160 case FLOOR_DIV_EXPR:
3161 case ROUND_DIV_EXPR:
3162 case TRUNC_MOD_EXPR:
3164 case FLOOR_MOD_EXPR:
3165 case ROUND_MOD_EXPR:
3167 case EXACT_DIV_EXPR:
3177 CHECK_OP (0, "Invalid operand to binary operator");
3178 CHECK_OP (1, "Invalid operand to binary operator");
3190 /* Verify STMT, return true if STMT is not in GIMPLE form.
3191 TODO: Implement type checking. */
3194 verify_stmt (tree stmt, bool last_in_block)
3198 if (!is_gimple_stmt (stmt))
3200 error ("Is not a valid GIMPLE statement.");
3204 addr = walk_tree (&stmt, verify_expr, NULL, NULL);
3207 debug_generic_stmt (addr);
3211 /* If the statement is marked as part of an EH region, then it is
3212 expected that the statement could throw. Verify that when we
3213 have optimizations that simplify statements such that we prove
3214 that they cannot throw, that we update other data structures
3216 if (lookup_stmt_eh_region (stmt) >= 0)
3218 if (!tree_could_throw_p (stmt))
3220 error ("Statement marked for throw, but doesn%'t.");
3223 if (!last_in_block && tree_can_throw_internal (stmt))
3225 error ("Statement marked for throw in middle of block.");
3233 debug_generic_stmt (stmt);
3238 /* Return true when the T can be shared. */
3241 tree_node_can_be_shared (tree t)
3243 if (IS_TYPE_OR_DECL_P (t)
3244 /* We check for constants explicitly since they are not considered
3245 gimple invariants if they overflowed. */
3246 || CONSTANT_CLASS_P (t)
3247 || is_gimple_min_invariant (t)
3248 || TREE_CODE (t) == SSA_NAME)
3251 while (((TREE_CODE (t) == ARRAY_REF || TREE_CODE (t) == ARRAY_RANGE_REF)
3252 /* We check for constants explicitly since they are not considered
3253 gimple invariants if they overflowed. */
3254 && (CONSTANT_CLASS_P (TREE_OPERAND (t, 1))
3255 || is_gimple_min_invariant (TREE_OPERAND (t, 1))))
3256 || (TREE_CODE (t) == COMPONENT_REF
3257 || TREE_CODE (t) == REALPART_EXPR
3258 || TREE_CODE (t) == IMAGPART_EXPR))
3259 t = TREE_OPERAND (t, 0);
3268 /* Called via walk_trees. Verify tree sharing. */
3271 verify_node_sharing (tree * tp, int *walk_subtrees, void *data)
3273 htab_t htab = (htab_t) data;
3276 if (tree_node_can_be_shared (*tp))
3278 *walk_subtrees = false;
3282 slot = htab_find_slot (htab, *tp, INSERT);
3291 /* Verify the GIMPLE statement chain. */
3297 block_stmt_iterator bsi;
3302 timevar_push (TV_TREE_STMT_VERIFY);
3303 htab = htab_create (37, htab_hash_pointer, htab_eq_pointer, NULL);
3310 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
3312 int phi_num_args = PHI_NUM_ARGS (phi);
3314 for (i = 0; i < phi_num_args; i++)
3316 tree t = PHI_ARG_DEF (phi, i);
3319 /* Addressable variables do have SSA_NAMEs but they
3320 are not considered gimple values. */
3321 if (TREE_CODE (t) != SSA_NAME
3322 && TREE_CODE (t) != FUNCTION_DECL
3323 && !is_gimple_val (t))
3325 error ("PHI def is not a GIMPLE value");
3326 debug_generic_stmt (phi);
3327 debug_generic_stmt (t);
3331 addr = walk_tree (&t, verify_expr, NULL, NULL);
3334 debug_generic_stmt (addr);
3338 addr = walk_tree (&t, verify_node_sharing, htab, NULL);
3341 error ("Incorrect sharing of tree nodes");
3342 debug_generic_stmt (phi);
3343 debug_generic_stmt (addr);
3349 for (bsi = bsi_start (bb); !bsi_end_p (bsi); )
3351 tree stmt = bsi_stmt (bsi);
3353 err |= verify_stmt (stmt, bsi_end_p (bsi));
3354 addr = walk_tree (&stmt, verify_node_sharing, htab, NULL);
3357 error ("Incorrect sharing of tree nodes");
3358 debug_generic_stmt (stmt);
3359 debug_generic_stmt (addr);
3366 internal_error ("verify_stmts failed.");
3369 timevar_pop (TV_TREE_STMT_VERIFY);
3373 /* Verifies that the flow information is OK. */
3376 tree_verify_flow_info (void)
3380 block_stmt_iterator bsi;
3385 if (ENTRY_BLOCK_PTR->stmt_list)
3387 error ("ENTRY_BLOCK has a statement list associated with it\n");
3391 if (EXIT_BLOCK_PTR->stmt_list)
3393 error ("EXIT_BLOCK has a statement list associated with it\n");
3397 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
3398 if (e->flags & EDGE_FALLTHRU)
3400 error ("Fallthru to exit from bb %d\n", e->src->index);
3406 bool found_ctrl_stmt = false;
3408 /* Skip labels on the start of basic block. */
3409 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3411 if (TREE_CODE (bsi_stmt (bsi)) != LABEL_EXPR)
3414 if (label_to_block (LABEL_EXPR_LABEL (bsi_stmt (bsi))) != bb)
3416 tree stmt = bsi_stmt (bsi);
3417 error ("Label %s to block does not match in bb %d\n",
3418 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt))),
3423 if (decl_function_context (LABEL_EXPR_LABEL (bsi_stmt (bsi)))
3424 != current_function_decl)
3426 tree stmt = bsi_stmt (bsi);
3427 error ("Label %s has incorrect context in bb %d\n",
3428 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt))),
3434 /* Verify that body of basic block BB is free of control flow. */
3435 for (; !bsi_end_p (bsi); bsi_next (&bsi))
3437 tree stmt = bsi_stmt (bsi);
3439 if (found_ctrl_stmt)
3441 error ("Control flow in the middle of basic block %d\n",
3446 if (stmt_ends_bb_p (stmt))
3447 found_ctrl_stmt = true;
3449 if (TREE_CODE (stmt) == LABEL_EXPR)
3451 error ("Label %s in the middle of basic block %d\n",
3452 IDENTIFIER_POINTER (DECL_NAME (stmt)),
3457 bsi = bsi_last (bb);
3458 if (bsi_end_p (bsi))
3461 stmt = bsi_stmt (bsi);
3463 if (is_ctrl_stmt (stmt))
3465 FOR_EACH_EDGE (e, ei, bb->succs)
3466 if (e->flags & EDGE_FALLTHRU)
3468 error ("Fallthru edge after a control statement in bb %d \n",
3474 switch (TREE_CODE (stmt))
3480 if (TREE_CODE (COND_EXPR_THEN (stmt)) != GOTO_EXPR
3481 || TREE_CODE (COND_EXPR_ELSE (stmt)) != GOTO_EXPR)
3483 error ("Structured COND_EXPR at the end of bb %d\n", bb->index);
3487 extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
3489 if (!true_edge || !false_edge
3490 || !(true_edge->flags & EDGE_TRUE_VALUE)
3491 || !(false_edge->flags & EDGE_FALSE_VALUE)
3492 || (true_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL))
3493 || (false_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL))
3494 || EDGE_COUNT (bb->succs) >= 3)
3496 error ("Wrong outgoing edge flags at end of bb %d\n",
3501 if (!has_label_p (true_edge->dest,
3502 GOTO_DESTINATION (COND_EXPR_THEN (stmt))))
3504 error ("%<then%> label does not match edge at end of bb %d\n",
3509 if (!has_label_p (false_edge->dest,
3510 GOTO_DESTINATION (COND_EXPR_ELSE (stmt))))
3512 error ("%<else%> label does not match edge at end of bb %d\n",
3520 if (simple_goto_p (stmt))
3522 error ("Explicit goto at end of bb %d\n", bb->index);
3527 /* FIXME. We should double check that the labels in the
3528 destination blocks have their address taken. */
3529 FOR_EACH_EDGE (e, ei, bb->succs)
3530 if ((e->flags & (EDGE_FALLTHRU | EDGE_TRUE_VALUE
3531 | EDGE_FALSE_VALUE))
3532 || !(e->flags & EDGE_ABNORMAL))
3534 error ("Wrong outgoing edge flags at end of bb %d\n",
3542 if (EDGE_COUNT (bb->succs) != 1
3543 || (EDGE_SUCC (bb, 0)->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL
3544 | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
3546 error ("Wrong outgoing edge flags at end of bb %d\n", bb->index);
3549 if (EDGE_SUCC (bb, 0)->dest != EXIT_BLOCK_PTR)
3551 error ("Return edge does not point to exit in bb %d\n",
3564 vec = SWITCH_LABELS (stmt);
3565 n = TREE_VEC_LENGTH (vec);
3567 /* Mark all the destination basic blocks. */
3568 for (i = 0; i < n; ++i)
3570 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
3571 basic_block label_bb = label_to_block (lab);
3573 gcc_assert (!label_bb->aux || label_bb->aux == (void *)1);
3574 label_bb->aux = (void *)1;
3577 /* Verify that the case labels are sorted. */
3578 prev = TREE_VEC_ELT (vec, 0);
3579 for (i = 1; i < n - 1; ++i)
3581 tree c = TREE_VEC_ELT (vec, i);
3584 error ("Found default case not at end of case vector");
3588 if (! tree_int_cst_lt (CASE_LOW (prev), CASE_LOW (c)))
3590 error ("Case labels not sorted:\n ");
3591 print_generic_expr (stderr, prev, 0);
3592 fprintf (stderr," is greater than ");
3593 print_generic_expr (stderr, c, 0);
3594 fprintf (stderr," but comes before it.\n");
3599 if (CASE_LOW (TREE_VEC_ELT (vec, n - 1)))
3601 error ("No default case found at end of case vector");
3605 FOR_EACH_EDGE (e, ei, bb->succs)
3609 error ("Extra outgoing edge %d->%d\n",
3610 bb->index, e->dest->index);
3613 e->dest->aux = (void *)2;
3614 if ((e->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL
3615 | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
3617 error ("Wrong outgoing edge flags at end of bb %d\n",
3623 /* Check that we have all of them. */
3624 for (i = 0; i < n; ++i)
3626 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
3627 basic_block label_bb = label_to_block (lab);
3629 if (label_bb->aux != (void *)2)
3631 error ("Missing edge %i->%i\n",
3632 bb->index, label_bb->index);
3637 FOR_EACH_EDGE (e, ei, bb->succs)
3638 e->dest->aux = (void *)0;
3645 if (dom_computed[CDI_DOMINATORS] >= DOM_NO_FAST_QUERY)
3646 verify_dominators (CDI_DOMINATORS);
3652 /* Updates phi nodes after creating a forwarder block joined
3653 by edge FALLTHRU. */
3656 tree_make_forwarder_block (edge fallthru)
3660 basic_block dummy, bb;
3661 tree phi, new_phi, var, prev, next;
3663 dummy = fallthru->src;
3664 bb = fallthru->dest;
3666 if (EDGE_COUNT (bb->preds) == 1)
3669 /* If we redirected a branch we must create new phi nodes at the
3671 for (phi = phi_nodes (dummy); phi; phi = PHI_CHAIN (phi))
3673 var = PHI_RESULT (phi);
3674 new_phi = create_phi_node (var, bb);
3675 SSA_NAME_DEF_STMT (var) = new_phi;
3676 SET_PHI_RESULT (phi, make_ssa_name (SSA_NAME_VAR (var), phi));
3677 add_phi_arg (&new_phi, PHI_RESULT (phi), fallthru);
3680 /* Ensure that the PHI node chain is in the same order. */
3682 for (phi = phi_nodes (bb); phi; phi = next)
3684 next = PHI_CHAIN (phi);
3685 PHI_CHAIN (phi) = prev;
3688 set_phi_nodes (bb, prev);
3690 /* Add the arguments we have stored on edges. */
3691 FOR_EACH_EDGE (e, ei, bb->preds)
3696 for (phi = phi_nodes (bb), var = PENDING_STMT (e);
3698 phi = PHI_CHAIN (phi), var = TREE_CHAIN (var))
3699 add_phi_arg (&phi, TREE_VALUE (var), e);
3701 PENDING_STMT (e) = NULL;
3706 /* Return true if basic block BB does nothing except pass control
3707 flow to another block and that we can safely insert a label at
3708 the start of the successor block.
3710 As a precondition, we require that BB be not equal to
3714 tree_forwarder_block_p (basic_block bb)
3716 block_stmt_iterator bsi;
3720 /* BB must have a single outgoing edge. */
3721 if (EDGE_COUNT (bb->succs) != 1
3722 /* BB can not have any PHI nodes. This could potentially be
3723 relaxed early in compilation if we re-rewrote the variables
3724 appearing in any PHI nodes in forwarder blocks. */
3726 /* BB may not be a predecessor of EXIT_BLOCK_PTR. */
3727 || EDGE_SUCC (bb, 0)->dest == EXIT_BLOCK_PTR
3728 /* BB may not have an abnormal outgoing edge. */
3729 || (EDGE_SUCC (bb, 0)->flags & EDGE_ABNORMAL))
3733 gcc_assert (bb != ENTRY_BLOCK_PTR);
3736 /* Successors of the entry block are not forwarders. */
3737 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
3741 /* Now walk through the statements. We can ignore labels, anything else
3742 means this is not a forwarder block. */
3743 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3745 tree stmt = bsi_stmt (bsi);
3747 switch (TREE_CODE (stmt))
3750 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)))
3762 /* Thread jumps from BB. */
3765 thread_jumps_from_bb (basic_block bb)
3769 bool retval = false;
3771 /* Examine each of our block's successors to see if it is
3773 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
3778 basic_block dest, tmp, curr, old_dest;
3782 /* If the edge is abnormal or its destination is not
3783 forwardable, then there's nothing to do. */
3784 if ((e->flags & EDGE_ABNORMAL)
3785 || !bb_ann (e->dest)->forwardable)
3791 /* Now walk through as many forwarder blocks as possible to find
3792 the ultimate destination we want to thread our jump to. */
3793 last = EDGE_SUCC (e->dest, 0);
3794 bb_ann (e->dest)->forwardable = 0;
3795 for (dest = EDGE_SUCC (e->dest, 0)->dest;
3796 bb_ann (dest)->forwardable;
3797 last = EDGE_SUCC (dest, 0),
3798 dest = EDGE_SUCC (dest, 0)->dest)
3799 bb_ann (dest)->forwardable = 0;
3801 /* Reset the forwardable marks to 1. */
3804 tmp = EDGE_SUCC (tmp, 0)->dest)
3805 bb_ann (tmp)->forwardable = 1;
3807 if (dest == e->dest)
3813 old = find_edge (bb, dest);
3816 /* If there already is an edge, check whether the values in
3817 phi nodes differ. */
3818 if (!phi_alternatives_equal (dest, last, old))
3820 /* The previous block is forwarder. Redirect our jump
3821 to that target instead since we know it has no PHI
3822 nodes that will need updating. */
3825 /* That might mean that no forwarding at all is
3827 if (dest == e->dest)
3833 old = find_edge (bb, dest);
3837 /* Perform the redirection. */
3840 freq = EDGE_FREQUENCY (e);
3842 e = redirect_edge_and_branch (e, dest);
3844 /* Update the profile. */
3845 if (profile_status != PROFILE_ABSENT)
3846 for (curr = old_dest;
3848 curr = EDGE_SUCC (curr, 0)->dest)
3850 curr->frequency -= freq;
3851 if (curr->frequency < 0)
3852 curr->frequency = 0;
3853 curr->count -= count;
3854 if (curr->count < 0)
3856 EDGE_SUCC (curr, 0)->count -= count;
3857 if (EDGE_SUCC (curr, 0)->count < 0)
3858 EDGE_SUCC (curr, 0)->count = 0;
3863 /* Update PHI nodes. We know that the new argument should
3864 have the same value as the argument associated with LAST.
3865 Otherwise we would have changed our target block
3867 for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi))
3869 arg = phi_arg_from_edge (phi, last);
3870 gcc_assert (arg >= 0);
3871 add_phi_arg (&phi, PHI_ARG_DEF (phi, arg), e);
3875 /* Remove the unreachable blocks (observe that if all blocks
3876 were reachable before, only those in the path we threaded
3877 over and did not have any predecessor outside of the path
3878 become unreachable). */
3879 for (; old_dest != dest; old_dest = tmp)
3881 tmp = EDGE_SUCC (old_dest, 0)->dest;
3883 if (EDGE_COUNT (old_dest->preds) > 0)
3886 delete_basic_block (old_dest);
3889 /* Update the dominators. */
3890 if (dom_info_available_p (CDI_DOMINATORS))
3892 /* If the dominator of the destination was in the
3893 path, set its dominator to the start of the
3895 if (get_immediate_dominator (CDI_DOMINATORS, old_dest) == NULL)
3896 set_immediate_dominator (CDI_DOMINATORS, old_dest, bb);
3898 /* Now proceed like if we forwarded just over one edge at a
3899 time. Algorithm for forwarding edge S --> A over
3900 edge A --> B then is
3903 && !dominated_by (S, B))
3904 idom (B) = idom (A);
3905 recount_idom (A); */
3907 for (; old_dest != dest; old_dest = tmp)
3911 tmp = EDGE_SUCC (old_dest, 0)->dest;
3913 if (get_immediate_dominator (CDI_DOMINATORS, tmp) == old_dest
3914 && !dominated_by_p (CDI_DOMINATORS, bb, tmp))
3916 dom = get_immediate_dominator (CDI_DOMINATORS, old_dest);
3917 set_immediate_dominator (CDI_DOMINATORS, tmp, dom);
3920 dom = recount_dominator (CDI_DOMINATORS, old_dest);
3921 set_immediate_dominator (CDI_DOMINATORS, old_dest, dom);
3930 /* Thread jumps over empty statements.
3932 This code should _not_ thread over obviously equivalent conditions
3933 as that requires nontrivial updates to the SSA graph.
3935 As a precondition, we require that all basic blocks be reachable.
3936 That is, there should be no opportunities left for
3937 delete_unreachable_blocks. */
3943 bool retval = false;
3944 basic_block *worklist = xmalloc (sizeof (basic_block) * last_basic_block);
3945 unsigned int size = 0;
3949 bb_ann (bb)->forwardable = tree_forwarder_block_p (bb);
3950 bb->flags &= ~BB_VISITED;
3953 /* Initialize WORKLIST by putting non-forwarder blocks that
3954 immediately precede forwarder blocks because those are the ones
3955 that we know we can thread jumps from. We use BB_VISITED to
3956 indicate whether a given basic block is in WORKLIST or not,
3957 thereby avoiding duplicates in WORKLIST. */
3963 /* We are not interested in finding non-forwarder blocks
3964 directly. We want to find non-forwarder blocks as
3965 predecessors of a forwarder block. */
3966 if (!bb_ann (bb)->forwardable)
3969 /* Now we know BB is a forwarder block. Visit each of its
3970 incoming edges and add to WORKLIST all non-forwarder blocks
3971 among BB's predecessors. */
3972 FOR_EACH_EDGE (e, ei, bb->preds)
3974 /* We are not interested in threading jumps from a forwarder
3976 if (!bb_ann (e->src)->forwardable
3977 /* We don't want to visit ENTRY_BLOCK_PTR. */
3978 && e->src->index >= 0
3979 /* We don't want to put a duplicate into WORKLIST. */
3980 && (e->src->flags & BB_VISITED) == 0)
3982 e->src->flags |= BB_VISITED;
3983 worklist[size] = e->src;
3989 /* Now let's drain WORKLIST. */
3993 bb = worklist[size];
3995 /* BB->INDEX is not longer in WORKLIST, so clear BB_VISITED. */
3996 bb->flags &= ~BB_VISITED;
3998 if (thread_jumps_from_bb (bb))
4002 if (tree_forwarder_block_p (bb))
4007 bb_ann (bb)->forwardable = true;
4009 /* Attempts to thread through BB may have been blocked
4010 because BB was not a forwarder block before. Now
4011 that BB is a forwarder block, we should revisit BB's
4013 FOR_EACH_EDGE (f, ej, bb->preds)
4015 /* We are not interested in threading jumps from a
4017 if (!bb_ann (f->src)->forwardable
4018 /* We don't want to visit ENTRY_BLOCK_PTR. */
4019 && f->src->index >= 0
4020 /* We don't want to put a duplicate into WORKLIST. */
4021 && (f->src->flags & BB_VISITED) == 0)
4023 f->src->flags |= BB_VISITED;
4024 worklist[size] = f->src;
4038 /* Return a non-special label in the head of basic block BLOCK.
4039 Create one if it doesn't exist. */
4042 tree_block_label (basic_block bb)
4044 block_stmt_iterator i, s = bsi_start (bb);
4048 for (i = s; !bsi_end_p (i); first = false, bsi_next (&i))
4050 stmt = bsi_stmt (i);
4051 if (TREE_CODE (stmt) != LABEL_EXPR)
4053 label = LABEL_EXPR_LABEL (stmt);
4054 if (!DECL_NONLOCAL (label))
4057 bsi_move_before (&i, &s);
4062 label = create_artificial_label ();
4063 stmt = build1 (LABEL_EXPR, void_type_node, label);
4064 bsi_insert_before (&s, stmt, BSI_NEW_STMT);
4069 /* Attempt to perform edge redirection by replacing a possibly complex
4070 jump instruction by a goto or by removing the jump completely.
4071 This can apply only if all edges now point to the same block. The
4072 parameters and return values are equivalent to
4073 redirect_edge_and_branch. */
4076 tree_try_redirect_by_replacing_jump (edge e, basic_block target)
4078 basic_block src = e->src;
4080 block_stmt_iterator b;
4084 /* Verify that all targets will be TARGET. */
4085 FOR_EACH_EDGE (tmp, ei, src->succs)
4086 if (tmp->dest != target && tmp != e)
4095 stmt = bsi_stmt (b);
4097 if (TREE_CODE (stmt) == COND_EXPR
4098 || TREE_CODE (stmt) == SWITCH_EXPR)
4101 e = ssa_redirect_edge (e, target);
4102 e->flags = EDGE_FALLTHRU;
4110 /* Redirect E to DEST. Return NULL on failure. Otherwise, return the
4111 edge representing the redirected branch. */
4114 tree_redirect_edge_and_branch (edge e, basic_block dest)
4116 basic_block bb = e->src;
4117 block_stmt_iterator bsi;
4121 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
4124 if (e->src != ENTRY_BLOCK_PTR
4125 && (ret = tree_try_redirect_by_replacing_jump (e, dest)))
4128 if (e->dest == dest)
4131 label = tree_block_label (dest);
4133 bsi = bsi_last (bb);
4134 stmt = bsi_end_p (bsi) ? NULL : bsi_stmt (bsi);
4136 switch (stmt ? TREE_CODE (stmt) : ERROR_MARK)
4139 stmt = (e->flags & EDGE_TRUE_VALUE
4140 ? COND_EXPR_THEN (stmt)
4141 : COND_EXPR_ELSE (stmt));
4142 GOTO_DESTINATION (stmt) = label;
4146 /* No non-abnormal edges should lead from a non-simple goto, and
4147 simple ones should be represented implicitly. */
4152 tree vec = SWITCH_LABELS (stmt);
4153 size_t i, n = TREE_VEC_LENGTH (vec);
4155 for (i = 0; i < n; ++i)
4157 tree elt = TREE_VEC_ELT (vec, i);
4158 if (label_to_block (CASE_LABEL (elt)) == e->dest)
4159 CASE_LABEL (elt) = label;
4166 e->flags |= EDGE_FALLTHRU;
4170 /* Otherwise it must be a fallthru edge, and we don't need to
4171 do anything besides redirecting it. */
4172 gcc_assert (e->flags & EDGE_FALLTHRU);
4176 /* Update/insert PHI nodes as necessary. */
4178 /* Now update the edges in the CFG. */
4179 e = ssa_redirect_edge (e, dest);
4185 /* Simple wrapper, as we can always redirect fallthru edges. */
4188 tree_redirect_edge_and_branch_force (edge e, basic_block dest)
4190 e = tree_redirect_edge_and_branch (e, dest);
4197 /* Splits basic block BB after statement STMT (but at least after the
4198 labels). If STMT is NULL, BB is split just after the labels. */
4201 tree_split_block (basic_block bb, void *stmt)
4203 block_stmt_iterator bsi, bsi_tgt;
4209 new_bb = create_empty_bb (bb);
4211 /* Redirect the outgoing edges. */
4212 new_bb->succs = bb->succs;
4214 FOR_EACH_EDGE (e, ei, new_bb->succs)
4217 if (stmt && TREE_CODE ((tree) stmt) == LABEL_EXPR)
4220 /* Move everything from BSI to the new basic block. */
4221 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4223 act = bsi_stmt (bsi);
4224 if (TREE_CODE (act) == LABEL_EXPR)
4237 bsi_tgt = bsi_start (new_bb);
4238 while (!bsi_end_p (bsi))
4240 act = bsi_stmt (bsi);
4242 bsi_insert_after (&bsi_tgt, act, BSI_NEW_STMT);
4249 /* Moves basic block BB after block AFTER. */
4252 tree_move_block_after (basic_block bb, basic_block after)
4254 if (bb->prev_bb == after)
4258 link_block (bb, after);
4264 /* Return true if basic_block can be duplicated. */
4267 tree_can_duplicate_bb_p (basic_block bb ATTRIBUTE_UNUSED)
4272 /* Create a duplicate of the basic block BB. NOTE: This does not
4273 preserve SSA form. */
4276 tree_duplicate_bb (basic_block bb)
4279 block_stmt_iterator bsi, bsi_tgt;
4281 ssa_op_iter op_iter;
4283 new_bb = create_empty_bb (EXIT_BLOCK_PTR->prev_bb);
4285 /* First copy the phi nodes. We do not copy phi node arguments here,
4286 since the edges are not ready yet. Keep the chain of phi nodes in
4287 the same order, so that we can add them later. */
4288 for (phi = phi_nodes (bb); phi; phi = TREE_CHAIN (phi))
4290 mark_for_rewrite (PHI_RESULT (phi));
4291 create_phi_node (PHI_RESULT (phi), new_bb);
4293 set_phi_nodes (new_bb, nreverse (phi_nodes (new_bb)));
4295 bsi_tgt = bsi_start (new_bb);
4296 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4298 tree stmt = bsi_stmt (bsi);
4301 if (TREE_CODE (stmt) == LABEL_EXPR)
4304 /* Record the definitions. */
4305 get_stmt_operands (stmt);
4307 FOR_EACH_SSA_TREE_OPERAND (val, stmt, op_iter, SSA_OP_ALL_DEFS)
4308 mark_for_rewrite (val);
4310 copy = unshare_expr (stmt);
4312 /* Copy also the virtual operands. */
4313 get_stmt_ann (copy);
4314 copy_virtual_operands (copy, stmt);
4316 bsi_insert_after (&bsi_tgt, copy, BSI_NEW_STMT);
4322 /* Basic block BB_COPY was created by code duplication. Add phi node
4323 arguments for edges going out of BB_COPY. The blocks that were
4324 duplicated have rbi->duplicated set to one. */
4327 add_phi_args_after_copy_bb (basic_block bb_copy)
4329 basic_block bb, dest;
4332 tree phi, phi_copy, phi_next, def;
4334 bb = bb_copy->rbi->original;
4336 FOR_EACH_EDGE (e_copy, ei, bb_copy->succs)
4338 if (!phi_nodes (e_copy->dest))
4341 if (e_copy->dest->rbi->duplicated)
4342 dest = e_copy->dest->rbi->original;
4344 dest = e_copy->dest;
4346 e = find_edge (bb, dest);
4349 /* During loop unrolling the target of the latch edge is copied.
4350 In this case we are not looking for edge to dest, but to
4351 duplicated block whose original was dest. */
4352 FOR_EACH_EDGE (e, ei, bb->succs)
4353 if (e->dest->rbi->duplicated
4354 && e->dest->rbi->original == dest)
4357 gcc_assert (e != NULL);
4360 for (phi = phi_nodes (e->dest), phi_copy = phi_nodes (e_copy->dest);
4362 phi = phi_next, phi_copy = TREE_CHAIN (phi_copy))
4364 phi_next = TREE_CHAIN (phi);
4366 gcc_assert (PHI_RESULT (phi) == PHI_RESULT (phi_copy));
4367 def = PHI_ARG_DEF_FROM_EDGE (phi, e);
4368 add_phi_arg (&phi_copy, def, e_copy);
4373 /* Blocks in REGION_COPY array of length N_REGION were created by
4374 duplication of basic blocks. Add phi node arguments for edges
4375 going from these blocks. */
4378 add_phi_args_after_copy (basic_block *region_copy, unsigned n_region)
4382 for (i = 0; i < n_region; i++)
4383 region_copy[i]->rbi->duplicated = 1;
4385 for (i = 0; i < n_region; i++)
4386 add_phi_args_after_copy_bb (region_copy[i]);
4388 for (i = 0; i < n_region; i++)
4389 region_copy[i]->rbi->duplicated = 0;
4392 /* Maps the old ssa name FROM_NAME to TO_NAME. */
4394 struct ssa_name_map_entry
4400 /* Hash function for ssa_name_map_entry. */
4403 ssa_name_map_entry_hash (const void *entry)
4405 const struct ssa_name_map_entry *en = entry;
4406 return SSA_NAME_VERSION (en->from_name);
4409 /* Equality function for ssa_name_map_entry. */
4412 ssa_name_map_entry_eq (const void *in_table, const void *ssa_name)
4414 const struct ssa_name_map_entry *en = in_table;
4416 return en->from_name == ssa_name;
4419 /* Allocate duplicates of ssa names in list DEFINITIONS and store the mapping
4423 allocate_ssa_names (bitmap definitions, htab_t *map)
4426 struct ssa_name_map_entry *entry;
4432 *map = htab_create (10, ssa_name_map_entry_hash,
4433 ssa_name_map_entry_eq, free);
4434 EXECUTE_IF_SET_IN_BITMAP (definitions, 0, ver, bi)
4436 name = ssa_name (ver);
4437 slot = htab_find_slot_with_hash (*map, name, SSA_NAME_VERSION (name),
4443 entry = xmalloc (sizeof (struct ssa_name_map_entry));
4444 entry->from_name = name;
4447 entry->to_name = duplicate_ssa_name (name, SSA_NAME_DEF_STMT (name));
4451 /* Rewrite the definition DEF in statement STMT to new ssa name as specified
4452 by the mapping MAP. */
4455 rewrite_to_new_ssa_names_def (def_operand_p def, tree stmt, htab_t map)
4457 tree name = DEF_FROM_PTR (def);
4458 struct ssa_name_map_entry *entry;
4460 gcc_assert (TREE_CODE (name) == SSA_NAME);
4462 entry = htab_find_with_hash (map, name, SSA_NAME_VERSION (name));
4466 SET_DEF (def, entry->to_name);
4467 SSA_NAME_DEF_STMT (entry->to_name) = stmt;
4470 /* Rewrite the USE to new ssa name as specified by the mapping MAP. */
4473 rewrite_to_new_ssa_names_use (use_operand_p use, htab_t map)
4475 tree name = USE_FROM_PTR (use);
4476 struct ssa_name_map_entry *entry;
4478 if (TREE_CODE (name) != SSA_NAME)
4481 entry = htab_find_with_hash (map, name, SSA_NAME_VERSION (name));
4485 SET_USE (use, entry->to_name);
4488 /* Rewrite the ssa names in basic block BB to new ones as specified by the
4492 rewrite_to_new_ssa_names_bb (basic_block bb, htab_t map)
4498 block_stmt_iterator bsi;
4502 v_may_def_optype v_may_defs;
4503 v_must_def_optype v_must_defs;
4506 FOR_EACH_EDGE (e, ei, bb->preds)
4507 if (e->flags & EDGE_ABNORMAL)
4510 for (phi = phi_nodes (bb); phi; phi = TREE_CHAIN (phi))
4512 rewrite_to_new_ssa_names_def (PHI_RESULT_PTR (phi), phi, map);
4514 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (PHI_RESULT (phi)) = 1;
4517 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4519 stmt = bsi_stmt (bsi);
4520 get_stmt_operands (stmt);
4521 ann = stmt_ann (stmt);
4523 uses = USE_OPS (ann);
4524 for (i = 0; i < NUM_USES (uses); i++)
4525 rewrite_to_new_ssa_names_use (USE_OP_PTR (uses, i), map);
4527 defs = DEF_OPS (ann);
4528 for (i = 0; i < NUM_DEFS (defs); i++)
4529 rewrite_to_new_ssa_names_def (DEF_OP_PTR (defs, i), stmt, map);
4531 vuses = VUSE_OPS (ann);
4532 for (i = 0; i < NUM_VUSES (vuses); i++)
4533 rewrite_to_new_ssa_names_use (VUSE_OP_PTR (vuses, i), map);
4535 v_may_defs = V_MAY_DEF_OPS (ann);
4536 for (i = 0; i < NUM_V_MAY_DEFS (v_may_defs); i++)
4538 rewrite_to_new_ssa_names_use
4539 (V_MAY_DEF_OP_PTR (v_may_defs, i), map);
4540 rewrite_to_new_ssa_names_def
4541 (V_MAY_DEF_RESULT_PTR (v_may_defs, i), stmt, map);
4544 v_must_defs = V_MUST_DEF_OPS (ann);
4545 for (i = 0; i < NUM_V_MUST_DEFS (v_must_defs); i++)
4546 rewrite_to_new_ssa_names_def
4547 (V_MUST_DEF_OP_PTR (v_must_defs, i), stmt, map);
4550 FOR_EACH_EDGE (e, ei, bb->succs)
4551 for (phi = phi_nodes (e->dest); phi; phi = TREE_CHAIN (phi))
4553 rewrite_to_new_ssa_names_use
4554 (PHI_ARG_DEF_PTR_FROM_EDGE (phi, e), map);
4556 if (e->flags & EDGE_ABNORMAL)
4558 tree op = PHI_ARG_DEF_FROM_EDGE (phi, e);
4559 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op) = 1;
4564 /* Rewrite the ssa names in N_REGION blocks REGION to the new ones as specified
4565 by the mapping MAP. */
4568 rewrite_to_new_ssa_names (basic_block *region, unsigned n_region, htab_t map)
4572 for (r = 0; r < n_region; r++)
4573 rewrite_to_new_ssa_names_bb (region[r], map);
4576 /* Duplicates a REGION (set of N_REGION basic blocks) with just a single
4577 important exit edge EXIT. By important we mean that no SSA name defined
4578 inside region is live over the other exit edges of the region. All entry
4579 edges to the region must go to ENTRY->dest. The edge ENTRY is redirected
4580 to the duplicate of the region. SSA form, dominance and loop information
4581 is updated. The new basic blocks are stored to REGION_COPY in the same
4582 order as they had in REGION, provided that REGION_COPY is not NULL.
4583 The function returns false if it is unable to copy the region,
4587 tree_duplicate_sese_region (edge entry, edge exit,
4588 basic_block *region, unsigned n_region,
4589 basic_block *region_copy)
4591 unsigned i, n_doms, ver;
4592 bool free_region_copy = false, copying_header = false;
4593 struct loop *loop = entry->dest->loop_father;
4598 htab_t ssa_name_map = NULL;
4602 if (!can_copy_bbs_p (region, n_region))
4605 /* Some sanity checking. Note that we do not check for all possible
4606 missuses of the functions. I.e. if you ask to copy something weird,
4607 it will work, but the state of structures probably will not be
4610 for (i = 0; i < n_region; i++)
4612 /* We do not handle subloops, i.e. all the blocks must belong to the
4614 if (region[i]->loop_father != loop)
4617 if (region[i] != entry->dest
4618 && region[i] == loop->header)
4624 /* In case the function is used for loop header copying (which is the primary
4625 use), ensure that EXIT and its copy will be new latch and entry edges. */
4626 if (loop->header == entry->dest)
4628 copying_header = true;
4629 loop->copy = loop->outer;
4631 if (!dominated_by_p (CDI_DOMINATORS, loop->latch, exit->src))
4634 for (i = 0; i < n_region; i++)
4635 if (region[i] != exit->src
4636 && dominated_by_p (CDI_DOMINATORS, region[i], exit->src))
4642 region_copy = xmalloc (sizeof (basic_block) * n_region);
4643 free_region_copy = true;
4646 gcc_assert (!any_marked_for_rewrite_p ());
4648 /* Record blocks outside the region that are duplicated by something
4650 doms = xmalloc (sizeof (basic_block) * n_basic_blocks);
4651 n_doms = get_dominated_by_region (CDI_DOMINATORS, region, n_region, doms);
4653 copy_bbs (region, n_region, region_copy, &exit, 1, &exit_copy, loop);
4654 definitions = marked_ssa_names ();
4658 loop->header = exit->dest;
4659 loop->latch = exit->src;
4662 /* Redirect the entry and add the phi node arguments. */
4663 redirected = redirect_edge_and_branch (entry, entry->dest->rbi->copy);
4664 gcc_assert (redirected != NULL);
4665 for (phi = phi_nodes (entry->dest), var = PENDING_STMT (entry);
4667 phi = TREE_CHAIN (phi), var = TREE_CHAIN (var))
4668 add_phi_arg (&phi, TREE_VALUE (var), entry);
4669 PENDING_STMT (entry) = NULL;
4671 /* Concerning updating of dominators: We must recount dominators
4672 for entry block and its copy. Anything that is outside of the region, but
4673 was dominated by something inside needs recounting as well. */
4674 set_immediate_dominator (CDI_DOMINATORS, entry->dest, entry->src);
4675 doms[n_doms++] = entry->dest->rbi->original;
4676 iterate_fix_dominators (CDI_DOMINATORS, doms, n_doms);
4679 /* Add the other phi node arguments. */
4680 add_phi_args_after_copy (region_copy, n_region);
4682 /* Add phi nodes for definitions at exit. TODO -- once we have immediate
4683 uses, it should be possible to emit phi nodes just for definitions that
4684 are used outside region. */
4685 EXECUTE_IF_SET_IN_BITMAP (definitions, 0, ver, bi)
4687 tree name = ssa_name (ver);
4689 phi = create_phi_node (name, exit->dest);
4690 add_phi_arg (&phi, name, exit);
4691 add_phi_arg (&phi, name, exit_copy);
4693 SSA_NAME_DEF_STMT (name) = phi;
4696 /* And create new definitions inside region and its copy. TODO -- once we
4697 have immediate uses, it might be better to leave definitions in region
4698 unchanged, create new ssa names for phi nodes on exit, and rewrite
4699 the uses, to avoid changing the copied region. */
4700 allocate_ssa_names (definitions, &ssa_name_map);
4701 rewrite_to_new_ssa_names (region, n_region, ssa_name_map);
4702 allocate_ssa_names (definitions, &ssa_name_map);
4703 rewrite_to_new_ssa_names (region_copy, n_region, ssa_name_map);
4704 htab_delete (ssa_name_map);
4706 if (free_region_copy)
4709 unmark_all_for_rewrite ();
4710 BITMAP_XFREE (definitions);
4715 /* Dump FUNCTION_DECL FN to file FILE using FLAGS (see TDF_* in tree.h) */
4718 dump_function_to_file (tree fn, FILE *file, int flags)
4720 tree arg, vars, var;
4721 bool ignore_topmost_bind = false, any_var = false;
4725 fprintf (file, "%s (", lang_hooks.decl_printable_name (fn, 2));
4727 arg = DECL_ARGUMENTS (fn);
4730 print_generic_expr (file, arg, dump_flags);
4731 if (TREE_CHAIN (arg))
4732 fprintf (file, ", ");
4733 arg = TREE_CHAIN (arg);
4735 fprintf (file, ")\n");
4737 if (flags & TDF_RAW)
4739 dump_node (fn, TDF_SLIM | flags, file);
4743 /* When GIMPLE is lowered, the variables are no longer available in
4744 BIND_EXPRs, so display them separately. */
4745 if (cfun && cfun->unexpanded_var_list)
4747 ignore_topmost_bind = true;
4749 fprintf (file, "{\n");
4750 for (vars = cfun->unexpanded_var_list; vars; vars = TREE_CHAIN (vars))
4752 var = TREE_VALUE (vars);
4754 print_generic_decl (file, var, flags);
4755 fprintf (file, "\n");
4761 if (basic_block_info)
4763 /* Make a CFG based dump. */
4764 check_bb_profile (ENTRY_BLOCK_PTR, file);
4765 if (!ignore_topmost_bind)
4766 fprintf (file, "{\n");
4768 if (any_var && n_basic_blocks)
4769 fprintf (file, "\n");
4772 dump_generic_bb (file, bb, 2, flags);
4774 fprintf (file, "}\n");
4775 check_bb_profile (EXIT_BLOCK_PTR, file);
4781 /* Make a tree based dump. */
4782 chain = DECL_SAVED_TREE (fn);
4784 if (TREE_CODE (chain) == BIND_EXPR)
4786 if (ignore_topmost_bind)
4788 chain = BIND_EXPR_BODY (chain);
4796 if (!ignore_topmost_bind)
4797 fprintf (file, "{\n");
4802 fprintf (file, "\n");
4804 print_generic_stmt_indented (file, chain, flags, indent);
4805 if (ignore_topmost_bind)
4806 fprintf (file, "}\n");
4809 fprintf (file, "\n\n");
4813 /* Pretty print of the loops intermediate representation. */
4814 static void print_loop (FILE *, struct loop *, int);
4815 static void print_pred_bbs (FILE *, basic_block bb);
4816 static void print_succ_bbs (FILE *, basic_block bb);
4819 /* Print the predecessors indexes of edge E on FILE. */
4822 print_pred_bbs (FILE *file, basic_block bb)
4827 FOR_EACH_EDGE (e, ei, bb->preds)
4828 fprintf (file, "bb_%d", e->src->index);
4832 /* Print the successors indexes of edge E on FILE. */
4835 print_succ_bbs (FILE *file, basic_block bb)
4840 FOR_EACH_EDGE (e, ei, bb->succs)
4841 fprintf (file, "bb_%d", e->src->index);
4845 /* Pretty print LOOP on FILE, indented INDENT spaces. */
4848 print_loop (FILE *file, struct loop *loop, int indent)
4856 s_indent = (char *) alloca ((size_t) indent + 1);
4857 memset ((void *) s_indent, ' ', (size_t) indent);
4858 s_indent[indent] = '\0';
4860 /* Print the loop's header. */
4861 fprintf (file, "%sloop_%d\n", s_indent, loop->num);
4863 /* Print the loop's body. */
4864 fprintf (file, "%s{\n", s_indent);
4866 if (bb->loop_father == loop)
4868 /* Print the basic_block's header. */
4869 fprintf (file, "%s bb_%d (preds = {", s_indent, bb->index);
4870 print_pred_bbs (file, bb);
4871 fprintf (file, "}, succs = {");
4872 print_succ_bbs (file, bb);
4873 fprintf (file, "})\n");
4875 /* Print the basic_block's body. */
4876 fprintf (file, "%s {\n", s_indent);
4877 tree_dump_bb (bb, file, indent + 4);
4878 fprintf (file, "%s }\n", s_indent);
4881 print_loop (file, loop->inner, indent + 2);
4882 fprintf (file, "%s}\n", s_indent);
4883 print_loop (file, loop->next, indent);
4887 /* Follow a CFG edge from the entry point of the program, and on entry
4888 of a loop, pretty print the loop structure on FILE. */
4891 print_loop_ir (FILE *file)
4895 bb = BASIC_BLOCK (0);
4896 if (bb && bb->loop_father)
4897 print_loop (file, bb->loop_father, 0);
4901 /* Debugging loops structure at tree level. */
4904 debug_loop_ir (void)
4906 print_loop_ir (stderr);
4910 /* Return true if BB ends with a call, possibly followed by some
4911 instructions that must stay with the call. Return false,
4915 tree_block_ends_with_call_p (basic_block bb)
4917 block_stmt_iterator bsi = bsi_last (bb);
4918 return get_call_expr_in (bsi_stmt (bsi)) != NULL;
4922 /* Return true if BB ends with a conditional branch. Return false,
4926 tree_block_ends_with_condjump_p (basic_block bb)
4928 tree stmt = tsi_stmt (bsi_last (bb).tsi);
4929 return (TREE_CODE (stmt) == COND_EXPR);
4933 /* Return true if we need to add fake edge to exit at statement T.
4934 Helper function for tree_flow_call_edges_add. */
4937 need_fake_edge_p (tree t)
4941 /* NORETURN and LONGJMP calls already have an edge to exit.
4942 CONST, PURE and ALWAYS_RETURN calls do not need one.
4943 We don't currently check for CONST and PURE here, although
4944 it would be a good idea, because those attributes are
4945 figured out from the RTL in mark_constant_function, and
4946 the counter incrementation code from -fprofile-arcs
4947 leads to different results from -fbranch-probabilities. */
4948 call = get_call_expr_in (t);
4950 && !(call_expr_flags (call) &
4951 (ECF_NORETURN | ECF_LONGJMP | ECF_ALWAYS_RETURN)))
4954 if (TREE_CODE (t) == ASM_EXPR
4955 && (ASM_VOLATILE_P (t) || ASM_INPUT_P (t)))
4962 /* Add fake edges to the function exit for any non constant and non
4963 noreturn calls, volatile inline assembly in the bitmap of blocks
4964 specified by BLOCKS or to the whole CFG if BLOCKS is zero. Return
4965 the number of blocks that were split.
4967 The goal is to expose cases in which entering a basic block does
4968 not imply that all subsequent instructions must be executed. */
4971 tree_flow_call_edges_add (sbitmap blocks)
4974 int blocks_split = 0;
4975 int last_bb = last_basic_block;
4976 bool check_last_block = false;
4978 if (n_basic_blocks == 0)
4982 check_last_block = true;
4984 check_last_block = TEST_BIT (blocks, EXIT_BLOCK_PTR->prev_bb->index);
4986 /* In the last basic block, before epilogue generation, there will be
4987 a fallthru edge to EXIT. Special care is required if the last insn
4988 of the last basic block is a call because make_edge folds duplicate
4989 edges, which would result in the fallthru edge also being marked
4990 fake, which would result in the fallthru edge being removed by
4991 remove_fake_edges, which would result in an invalid CFG.
4993 Moreover, we can't elide the outgoing fake edge, since the block
4994 profiler needs to take this into account in order to solve the minimal
4995 spanning tree in the case that the call doesn't return.
4997 Handle this by adding a dummy instruction in a new last basic block. */
4998 if (check_last_block)
5001 basic_block bb = EXIT_BLOCK_PTR->prev_bb;
5002 block_stmt_iterator bsi = bsi_last (bb);
5004 if (!bsi_end_p (bsi))
5007 if (need_fake_edge_p (t))
5011 FOR_EACH_EDGE (e, ei, bb->succs)
5012 if (e->dest == EXIT_BLOCK_PTR)
5014 bsi_insert_on_edge (e, build_empty_stmt ());
5015 bsi_commit_edge_inserts ((int *)NULL);
5021 /* Now add fake edges to the function exit for any non constant
5022 calls since there is no way that we can determine if they will
5024 for (i = 0; i < last_bb; i++)
5026 basic_block bb = BASIC_BLOCK (i);
5027 block_stmt_iterator bsi;
5028 tree stmt, last_stmt;
5033 if (blocks && !TEST_BIT (blocks, i))
5036 bsi = bsi_last (bb);
5037 if (!bsi_end_p (bsi))
5039 last_stmt = bsi_stmt (bsi);
5042 stmt = bsi_stmt (bsi);
5043 if (need_fake_edge_p (stmt))
5046 /* The handling above of the final block before the
5047 epilogue should be enough to verify that there is
5048 no edge to the exit block in CFG already.
5049 Calling make_edge in such case would cause us to
5050 mark that edge as fake and remove it later. */
5051 #ifdef ENABLE_CHECKING
5052 if (stmt == last_stmt)
5055 FOR_EACH_EDGE (e, ei, bb->succs)
5056 gcc_assert (e->dest != EXIT_BLOCK_PTR);
5060 /* Note that the following may create a new basic block
5061 and renumber the existing basic blocks. */
5062 if (stmt != last_stmt)
5064 e = split_block (bb, stmt);
5068 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
5072 while (!bsi_end_p (bsi));
5077 verify_flow_info ();
5079 return blocks_split;
5083 tree_purge_dead_eh_edges (basic_block bb)
5085 bool changed = false;
5088 tree stmt = last_stmt (bb);
5090 if (stmt && tree_can_throw_internal (stmt))
5093 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
5095 if (e->flags & EDGE_EH)
5097 ssa_remove_edge (e);
5104 /* Removal of dead EH edges might change dominators of not
5105 just immediate successors. E.g. when bb1 is changed so that
5106 it no longer can throw and bb1->bb3 and bb1->bb4 are dead
5107 eh edges purged by this function in:
5119 idom(bb5) must be recomputed. For now just free the dominance
5122 free_dominance_info (CDI_DOMINATORS);
5128 tree_purge_all_dead_eh_edges (bitmap blocks)
5130 bool changed = false;
5134 EXECUTE_IF_SET_IN_BITMAP (blocks, 0, i, bi)
5136 changed |= tree_purge_dead_eh_edges (BASIC_BLOCK (i));
5142 struct cfg_hooks tree_cfg_hooks = {
5144 tree_verify_flow_info,
5145 tree_dump_bb, /* dump_bb */
5146 create_bb, /* create_basic_block */
5147 tree_redirect_edge_and_branch,/* redirect_edge_and_branch */
5148 tree_redirect_edge_and_branch_force,/* redirect_edge_and_branch_force */
5149 remove_bb, /* delete_basic_block */
5150 tree_split_block, /* split_block */
5151 tree_move_block_after, /* move_block_after */
5152 tree_can_merge_blocks_p, /* can_merge_blocks_p */
5153 tree_merge_blocks, /* merge_blocks */
5154 tree_predict_edge, /* predict_edge */
5155 tree_predicted_by_p, /* predicted_by_p */
5156 tree_can_duplicate_bb_p, /* can_duplicate_block_p */
5157 tree_duplicate_bb, /* duplicate_block */
5158 tree_split_edge, /* split_edge */
5159 tree_make_forwarder_block, /* make_forward_block */
5160 NULL, /* tidy_fallthru_edge */
5161 tree_block_ends_with_call_p, /* block_ends_with_call_p */
5162 tree_block_ends_with_condjump_p, /* block_ends_with_condjump_p */
5163 tree_flow_call_edges_add /* flow_call_edges_add */
5167 /* Split all critical edges. */
5170 split_critical_edges (void)
5178 FOR_EACH_EDGE (e, ei, bb->succs)
5179 if (EDGE_CRITICAL_P (e) && !(e->flags & EDGE_ABNORMAL))
5186 struct tree_opt_pass pass_split_crit_edges =
5188 "crited", /* name */
5190 split_critical_edges, /* execute */
5193 0, /* static_pass_number */
5194 TV_TREE_SPLIT_EDGES, /* tv_id */
5195 PROP_cfg, /* properties required */
5196 PROP_no_crit_edges, /* properties_provided */
5197 0, /* properties_destroyed */
5198 0, /* todo_flags_start */
5199 TODO_dump_func, /* todo_flags_finish */
5204 /* Return EXP if it is a valid GIMPLE rvalue, else gimplify it into
5205 a temporary, make sure and register it to be renamed if necessary,
5206 and finally return the temporary. Put the statements to compute
5207 EXP before the current statement in BSI. */
5210 gimplify_val (block_stmt_iterator *bsi, tree type, tree exp)
5212 tree t, new_stmt, orig_stmt;
5214 if (is_gimple_val (exp))
5217 t = make_rename_temp (type, NULL);
5218 new_stmt = build (MODIFY_EXPR, type, t, exp);
5220 orig_stmt = bsi_stmt (*bsi);
5221 SET_EXPR_LOCUS (new_stmt, EXPR_LOCUS (orig_stmt));
5222 TREE_BLOCK (new_stmt) = TREE_BLOCK (orig_stmt);
5224 bsi_insert_before (bsi, new_stmt, BSI_SAME_STMT);
5229 /* Build a ternary operation and gimplify it. Emit code before BSI.
5230 Return the gimple_val holding the result. */
5233 gimplify_build3 (block_stmt_iterator *bsi, enum tree_code code,
5234 tree type, tree a, tree b, tree c)
5238 ret = fold (build3 (code, type, a, b, c));
5241 return gimplify_val (bsi, type, ret);
5244 /* Build a binary operation and gimplify it. Emit code before BSI.
5245 Return the gimple_val holding the result. */
5248 gimplify_build2 (block_stmt_iterator *bsi, enum tree_code code,
5249 tree type, tree a, tree b)
5253 ret = fold (build2 (code, type, a, b));
5256 return gimplify_val (bsi, type, ret);
5259 /* Build a unary operation and gimplify it. Emit code before BSI.
5260 Return the gimple_val holding the result. */
5263 gimplify_build1 (block_stmt_iterator *bsi, enum tree_code code, tree type,
5268 ret = fold (build1 (code, type, a));
5271 return gimplify_val (bsi, type, ret);
5276 /* Emit return warnings. */
5279 execute_warn_function_return (void)
5281 #ifdef USE_MAPPED_LOCATION
5282 source_location location;
5290 if (warn_missing_noreturn
5291 && !TREE_THIS_VOLATILE (cfun->decl)
5292 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) == 0
5293 && !lang_hooks.function.missing_noreturn_ok_p (cfun->decl))
5294 warning ("%Jfunction might be possible candidate for "
5295 "attribute %<noreturn%>",
5298 /* If we have a path to EXIT, then we do return. */
5299 if (TREE_THIS_VOLATILE (cfun->decl)
5300 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) > 0)
5302 #ifdef USE_MAPPED_LOCATION
5303 location = UNKNOWN_LOCATION;
5307 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
5309 last = last_stmt (e->src);
5310 if (TREE_CODE (last) == RETURN_EXPR
5311 #ifdef USE_MAPPED_LOCATION
5312 && (location = EXPR_LOCATION (last)) != UNKNOWN_LOCATION)
5314 && (locus = EXPR_LOCUS (last)) != NULL)
5318 #ifdef USE_MAPPED_LOCATION
5319 if (location == UNKNOWN_LOCATION)
5320 location = cfun->function_end_locus;
5321 warning ("%H%<noreturn%> function does return", &location);
5324 locus = &cfun->function_end_locus;
5325 warning ("%H%<noreturn%> function does return", locus);
5329 /* If we see "return;" in some basic block, then we do reach the end
5330 without returning a value. */
5331 else if (warn_return_type
5332 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) > 0
5333 && !VOID_TYPE_P (TREE_TYPE (TREE_TYPE (cfun->decl))))
5335 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
5337 tree last = last_stmt (e->src);
5338 if (TREE_CODE (last) == RETURN_EXPR
5339 && TREE_OPERAND (last, 0) == NULL)
5341 #ifdef USE_MAPPED_LOCATION
5342 location = EXPR_LOCATION (last);
5343 if (location == UNKNOWN_LOCATION)
5344 location = cfun->function_end_locus;
5345 warning ("%Hcontrol reaches end of non-void function", &location);
5347 locus = EXPR_LOCUS (last);
5349 locus = &cfun->function_end_locus;
5350 warning ("%Hcontrol reaches end of non-void function", locus);
5359 /* Given a basic block B which ends with a conditional and has
5360 precisely two successors, determine which of the edges is taken if
5361 the conditional is true and which is taken if the conditional is
5362 false. Set TRUE_EDGE and FALSE_EDGE appropriately. */
5365 extract_true_false_edges_from_block (basic_block b,
5369 edge e = EDGE_SUCC (b, 0);
5371 if (e->flags & EDGE_TRUE_VALUE)
5374 *false_edge = EDGE_SUCC (b, 1);
5379 *true_edge = EDGE_SUCC (b, 1);
5383 struct tree_opt_pass pass_warn_function_return =
5387 execute_warn_function_return, /* execute */
5390 0, /* static_pass_number */
5392 PROP_cfg, /* properties_required */
5393 0, /* properties_provided */
5394 0, /* properties_destroyed */
5395 0, /* todo_flags_start */
5396 0, /* todo_flags_finish */
5400 #include "gt-tree-cfg.h"