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 ();
722 /* thread_jumps sometimes leaves further transformation
723 opportunities for itself, so iterate on it until nothing
725 while (thread_jumps ())
728 #ifdef ENABLE_CHECKING
731 gcc_assert (!cleanup_control_flow ());
732 gcc_assert (!delete_unreachable_blocks ());
736 /* Merging the blocks creates no new opportunities for the other
737 optimizations, so do it here. */
742 #ifdef ENABLE_CHECKING
745 timevar_pop (TV_TREE_CLEANUP_CFG);
750 /* Cleanup useless labels in basic blocks. This is something we wish
751 to do early because it allows us to group case labels before creating
752 the edges for the CFG, and it speeds up block statement iterators in
754 We only run this pass once, running it more than once is probably not
757 /* A map from basic block index to the leading label of that block. */
758 static tree *label_for_bb;
760 /* Callback for for_each_eh_region. Helper for cleanup_dead_labels. */
762 update_eh_label (struct eh_region *region)
764 tree old_label = get_eh_region_tree_label (region);
768 basic_block bb = label_to_block (old_label);
770 /* ??? After optimizing, there may be EH regions with labels
771 that have already been removed from the function body, so
772 there is no basic block for them. */
776 new_label = label_for_bb[bb->index];
777 set_eh_region_tree_label (region, new_label);
781 /* Given LABEL return the first label in the same basic block. */
783 main_block_label (tree label)
785 basic_block bb = label_to_block (label);
787 /* label_to_block possibly inserted undefined label into the chain. */
788 if (!label_for_bb[bb->index])
789 label_for_bb[bb->index] = label;
790 return label_for_bb[bb->index];
793 /* Cleanup redundant labels. This is a three-step process:
794 1) Find the leading label for each block.
795 2) Redirect all references to labels to the leading labels.
796 3) Cleanup all useless labels. */
799 cleanup_dead_labels (void)
802 label_for_bb = xcalloc (last_basic_block, sizeof (tree));
804 /* Find a suitable label for each block. We use the first user-defined
805 label if there is one, or otherwise just the first label we see. */
808 block_stmt_iterator i;
810 for (i = bsi_start (bb); !bsi_end_p (i); bsi_next (&i))
812 tree label, stmt = bsi_stmt (i);
814 if (TREE_CODE (stmt) != LABEL_EXPR)
817 label = LABEL_EXPR_LABEL (stmt);
819 /* If we have not yet seen a label for the current block,
820 remember this one and see if there are more labels. */
821 if (! label_for_bb[bb->index])
823 label_for_bb[bb->index] = label;
827 /* If we did see a label for the current block already, but it
828 is an artificially created label, replace it if the current
829 label is a user defined label. */
830 if (! DECL_ARTIFICIAL (label)
831 && DECL_ARTIFICIAL (label_for_bb[bb->index]))
833 label_for_bb[bb->index] = label;
839 /* Now redirect all jumps/branches to the selected label.
840 First do so for each block ending in a control statement. */
843 tree stmt = last_stmt (bb);
847 switch (TREE_CODE (stmt))
851 tree true_branch, false_branch;
853 true_branch = COND_EXPR_THEN (stmt);
854 false_branch = COND_EXPR_ELSE (stmt);
856 GOTO_DESTINATION (true_branch)
857 = main_block_label (GOTO_DESTINATION (true_branch));
858 GOTO_DESTINATION (false_branch)
859 = main_block_label (GOTO_DESTINATION (false_branch));
867 tree vec = SWITCH_LABELS (stmt);
868 size_t n = TREE_VEC_LENGTH (vec);
870 /* Replace all destination labels. */
871 for (i = 0; i < n; ++i)
872 CASE_LABEL (TREE_VEC_ELT (vec, i))
873 = main_block_label (CASE_LABEL (TREE_VEC_ELT (vec, i)));
878 /* We have to handle GOTO_EXPRs until they're removed, and we don't
879 remove them until after we've created the CFG edges. */
881 if (! computed_goto_p (stmt))
883 GOTO_DESTINATION (stmt)
884 = main_block_label (GOTO_DESTINATION (stmt));
893 for_each_eh_region (update_eh_label);
895 /* Finally, purge dead labels. All user-defined labels and labels that
896 can be the target of non-local gotos are preserved. */
899 block_stmt_iterator i;
900 tree label_for_this_bb = label_for_bb[bb->index];
902 if (! label_for_this_bb)
905 for (i = bsi_start (bb); !bsi_end_p (i); )
907 tree label, stmt = bsi_stmt (i);
909 if (TREE_CODE (stmt) != LABEL_EXPR)
912 label = LABEL_EXPR_LABEL (stmt);
914 if (label == label_for_this_bb
915 || ! DECL_ARTIFICIAL (label)
916 || DECL_NONLOCAL (label))
926 /* Look for blocks ending in a multiway branch (a SWITCH_EXPR in GIMPLE),
927 and scan the sorted vector of cases. Combine the ones jumping to the
929 Eg. three separate entries 1: 2: 3: become one entry 1..3: */
932 group_case_labels (void)
938 tree stmt = last_stmt (bb);
939 if (stmt && TREE_CODE (stmt) == SWITCH_EXPR)
941 tree labels = SWITCH_LABELS (stmt);
942 int old_size = TREE_VEC_LENGTH (labels);
943 int i, j, new_size = old_size;
944 tree default_case = TREE_VEC_ELT (labels, old_size - 1);
947 /* The default label is always the last case in a switch
948 statement after gimplification. */
949 default_label = CASE_LABEL (default_case);
951 /* Look for possible opportunities to merge cases.
952 Ignore the last element of the label vector because it
953 must be the default case. */
955 while (i < old_size - 2)
957 tree base_case, base_label, base_high, type;
958 base_case = TREE_VEC_ELT (labels, i);
960 gcc_assert (base_case);
961 base_label = CASE_LABEL (base_case);
963 /* Discard cases that have the same destination as the
965 if (base_label == default_label)
967 TREE_VEC_ELT (labels, i) = NULL_TREE;
973 type = TREE_TYPE (CASE_LOW (base_case));
974 base_high = CASE_HIGH (base_case) ?
975 CASE_HIGH (base_case) : CASE_LOW (base_case);
977 /* Try to merge case labels. Break out when we reach the end
978 of the label vector or when we cannot merge the next case
979 label with the current one. */
980 while (i < old_size - 2)
982 tree merge_case = TREE_VEC_ELT (labels, ++i);
983 tree merge_label = CASE_LABEL (merge_case);
984 tree t = int_const_binop (PLUS_EXPR, base_high,
985 integer_one_node, 1);
987 /* Merge the cases if they jump to the same place,
988 and their ranges are consecutive. */
989 if (merge_label == base_label
990 && tree_int_cst_equal (CASE_LOW (merge_case), t))
992 base_high = CASE_HIGH (merge_case) ?
993 CASE_HIGH (merge_case) : CASE_LOW (merge_case);
994 CASE_HIGH (base_case) = base_high;
995 TREE_VEC_ELT (labels, i) = NULL_TREE;
1003 /* Compress the case labels in the label vector, and adjust the
1004 length of the vector. */
1005 for (i = 0, j = 0; i < new_size; i++)
1007 while (! TREE_VEC_ELT (labels, j))
1009 TREE_VEC_ELT (labels, i) = TREE_VEC_ELT (labels, j++);
1011 TREE_VEC_LENGTH (labels) = new_size;
1016 /* Checks whether we can merge block B into block A. */
1019 tree_can_merge_blocks_p (basic_block a, basic_block b)
1022 block_stmt_iterator bsi;
1024 if (EDGE_COUNT (a->succs) != 1)
1027 if (EDGE_SUCC (a, 0)->flags & EDGE_ABNORMAL)
1030 if (EDGE_SUCC (a, 0)->dest != b)
1033 if (b == EXIT_BLOCK_PTR)
1036 if (EDGE_COUNT (b->preds) > 1)
1039 /* If A ends by a statement causing exceptions or something similar, we
1040 cannot merge the blocks. */
1041 stmt = last_stmt (a);
1042 if (stmt && stmt_ends_bb_p (stmt))
1045 /* Do not allow a block with only a non-local label to be merged. */
1046 if (stmt && TREE_CODE (stmt) == LABEL_EXPR
1047 && DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)))
1050 /* There may be no phi nodes at the start of b. Most of these degenerate
1051 phi nodes should be cleaned up by kill_redundant_phi_nodes. */
1055 /* Do not remove user labels. */
1056 for (bsi = bsi_start (b); !bsi_end_p (bsi); bsi_next (&bsi))
1058 stmt = bsi_stmt (bsi);
1059 if (TREE_CODE (stmt) != LABEL_EXPR)
1061 if (!DECL_ARTIFICIAL (LABEL_EXPR_LABEL (stmt)))
1069 /* Merge block B into block A. */
1072 tree_merge_blocks (basic_block a, basic_block b)
1074 block_stmt_iterator bsi;
1075 tree_stmt_iterator last;
1078 fprintf (dump_file, "Merging blocks %d and %d\n", a->index, b->index);
1080 /* Ensure that B follows A. */
1081 move_block_after (b, a);
1083 gcc_assert (EDGE_SUCC (a, 0)->flags & EDGE_FALLTHRU);
1084 gcc_assert (!last_stmt (a) || !stmt_ends_bb_p (last_stmt (a)));
1086 /* Remove labels from B and set bb_for_stmt to A for other statements. */
1087 for (bsi = bsi_start (b); !bsi_end_p (bsi);)
1089 if (TREE_CODE (bsi_stmt (bsi)) == LABEL_EXPR)
1093 set_bb_for_stmt (bsi_stmt (bsi), a);
1098 /* Merge the chains. */
1099 last = tsi_last (a->stmt_list);
1100 tsi_link_after (&last, b->stmt_list, TSI_NEW_STMT);
1101 b->stmt_list = NULL;
1105 /* Walk the function tree removing unnecessary statements.
1107 * Empty statement nodes are removed
1109 * Unnecessary TRY_FINALLY and TRY_CATCH blocks are removed
1111 * Unnecessary COND_EXPRs are removed
1113 * Some unnecessary BIND_EXPRs are removed
1115 Clearly more work could be done. The trick is doing the analysis
1116 and removal fast enough to be a net improvement in compile times.
1118 Note that when we remove a control structure such as a COND_EXPR
1119 BIND_EXPR, or TRY block, we will need to repeat this optimization pass
1120 to ensure we eliminate all the useless code. */
1131 static void remove_useless_stmts_1 (tree *, struct rus_data *);
1134 remove_useless_stmts_warn_notreached (tree stmt)
1136 if (EXPR_HAS_LOCATION (stmt))
1138 location_t loc = EXPR_LOCATION (stmt);
1139 warning ("%Hwill never be executed", &loc);
1143 switch (TREE_CODE (stmt))
1145 case STATEMENT_LIST:
1147 tree_stmt_iterator i;
1148 for (i = tsi_start (stmt); !tsi_end_p (i); tsi_next (&i))
1149 if (remove_useless_stmts_warn_notreached (tsi_stmt (i)))
1155 if (remove_useless_stmts_warn_notreached (COND_EXPR_COND (stmt)))
1157 if (remove_useless_stmts_warn_notreached (COND_EXPR_THEN (stmt)))
1159 if (remove_useless_stmts_warn_notreached (COND_EXPR_ELSE (stmt)))
1163 case TRY_FINALLY_EXPR:
1164 case TRY_CATCH_EXPR:
1165 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt, 0)))
1167 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt, 1)))
1172 return remove_useless_stmts_warn_notreached (CATCH_BODY (stmt));
1173 case EH_FILTER_EXPR:
1174 return remove_useless_stmts_warn_notreached (EH_FILTER_FAILURE (stmt));
1176 return remove_useless_stmts_warn_notreached (BIND_EXPR_BLOCK (stmt));
1179 /* Not a live container. */
1187 remove_useless_stmts_cond (tree *stmt_p, struct rus_data *data)
1189 tree then_clause, else_clause, cond;
1190 bool save_has_label, then_has_label, else_has_label;
1192 save_has_label = data->has_label;
1193 data->has_label = false;
1194 data->last_goto = NULL;
1196 remove_useless_stmts_1 (&COND_EXPR_THEN (*stmt_p), data);
1198 then_has_label = data->has_label;
1199 data->has_label = false;
1200 data->last_goto = NULL;
1202 remove_useless_stmts_1 (&COND_EXPR_ELSE (*stmt_p), data);
1204 else_has_label = data->has_label;
1205 data->has_label = save_has_label | then_has_label | else_has_label;
1208 then_clause = COND_EXPR_THEN (*stmt_p);
1209 else_clause = COND_EXPR_ELSE (*stmt_p);
1210 cond = COND_EXPR_COND (*stmt_p);
1212 /* If neither arm does anything at all, we can remove the whole IF. */
1213 if (!TREE_SIDE_EFFECTS (then_clause) && !TREE_SIDE_EFFECTS (else_clause))
1215 *stmt_p = build_empty_stmt ();
1216 data->repeat = true;
1219 /* If there are no reachable statements in an arm, then we can
1220 zap the entire conditional. */
1221 else if (integer_nonzerop (cond) && !else_has_label)
1223 if (warn_notreached)
1224 remove_useless_stmts_warn_notreached (else_clause);
1225 *stmt_p = then_clause;
1226 data->repeat = true;
1228 else if (integer_zerop (cond) && !then_has_label)
1230 if (warn_notreached)
1231 remove_useless_stmts_warn_notreached (then_clause);
1232 *stmt_p = else_clause;
1233 data->repeat = true;
1236 /* Check a couple of simple things on then/else with single stmts. */
1239 tree then_stmt = expr_only (then_clause);
1240 tree else_stmt = expr_only (else_clause);
1242 /* Notice branches to a common destination. */
1243 if (then_stmt && else_stmt
1244 && TREE_CODE (then_stmt) == GOTO_EXPR
1245 && TREE_CODE (else_stmt) == GOTO_EXPR
1246 && (GOTO_DESTINATION (then_stmt) == GOTO_DESTINATION (else_stmt)))
1248 *stmt_p = then_stmt;
1249 data->repeat = true;
1252 /* If the THEN/ELSE clause merely assigns a value to a variable or
1253 parameter which is already known to contain that value, then
1254 remove the useless THEN/ELSE clause. */
1255 else if (TREE_CODE (cond) == VAR_DECL || TREE_CODE (cond) == PARM_DECL)
1258 && TREE_CODE (else_stmt) == MODIFY_EXPR
1259 && TREE_OPERAND (else_stmt, 0) == cond
1260 && integer_zerop (TREE_OPERAND (else_stmt, 1)))
1261 COND_EXPR_ELSE (*stmt_p) = alloc_stmt_list ();
1263 else if ((TREE_CODE (cond) == EQ_EXPR || TREE_CODE (cond) == NE_EXPR)
1264 && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL
1265 || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL)
1266 && TREE_CONSTANT (TREE_OPERAND (cond, 1)))
1268 tree stmt = (TREE_CODE (cond) == EQ_EXPR
1269 ? then_stmt : else_stmt);
1270 tree *location = (TREE_CODE (cond) == EQ_EXPR
1271 ? &COND_EXPR_THEN (*stmt_p)
1272 : &COND_EXPR_ELSE (*stmt_p));
1275 && TREE_CODE (stmt) == MODIFY_EXPR
1276 && TREE_OPERAND (stmt, 0) == TREE_OPERAND (cond, 0)
1277 && TREE_OPERAND (stmt, 1) == TREE_OPERAND (cond, 1))
1278 *location = alloc_stmt_list ();
1282 /* Protect GOTOs in the arm of COND_EXPRs from being removed. They
1283 would be re-introduced during lowering. */
1284 data->last_goto = NULL;
1289 remove_useless_stmts_tf (tree *stmt_p, struct rus_data *data)
1291 bool save_may_branch, save_may_throw;
1292 bool this_may_branch, this_may_throw;
1294 /* Collect may_branch and may_throw information for the body only. */
1295 save_may_branch = data->may_branch;
1296 save_may_throw = data->may_throw;
1297 data->may_branch = false;
1298 data->may_throw = false;
1299 data->last_goto = NULL;
1301 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 0), data);
1303 this_may_branch = data->may_branch;
1304 this_may_throw = data->may_throw;
1305 data->may_branch |= save_may_branch;
1306 data->may_throw |= save_may_throw;
1307 data->last_goto = NULL;
1309 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 1), data);
1311 /* If the body is empty, then we can emit the FINALLY block without
1312 the enclosing TRY_FINALLY_EXPR. */
1313 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 0)))
1315 *stmt_p = TREE_OPERAND (*stmt_p, 1);
1316 data->repeat = true;
1319 /* If the handler is empty, then we can emit the TRY block without
1320 the enclosing TRY_FINALLY_EXPR. */
1321 else if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 1)))
1323 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1324 data->repeat = true;
1327 /* If the body neither throws, nor branches, then we can safely
1328 string the TRY and FINALLY blocks together. */
1329 else if (!this_may_branch && !this_may_throw)
1331 tree stmt = *stmt_p;
1332 *stmt_p = TREE_OPERAND (stmt, 0);
1333 append_to_statement_list (TREE_OPERAND (stmt, 1), stmt_p);
1334 data->repeat = true;
1340 remove_useless_stmts_tc (tree *stmt_p, struct rus_data *data)
1342 bool save_may_throw, this_may_throw;
1343 tree_stmt_iterator i;
1346 /* Collect may_throw information for the body only. */
1347 save_may_throw = data->may_throw;
1348 data->may_throw = false;
1349 data->last_goto = NULL;
1351 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 0), data);
1353 this_may_throw = data->may_throw;
1354 data->may_throw = save_may_throw;
1356 /* If the body cannot throw, then we can drop the entire TRY_CATCH_EXPR. */
1357 if (!this_may_throw)
1359 if (warn_notreached)
1360 remove_useless_stmts_warn_notreached (TREE_OPERAND (*stmt_p, 1));
1361 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1362 data->repeat = true;
1366 /* Process the catch clause specially. We may be able to tell that
1367 no exceptions propagate past this point. */
1369 this_may_throw = true;
1370 i = tsi_start (TREE_OPERAND (*stmt_p, 1));
1371 stmt = tsi_stmt (i);
1372 data->last_goto = NULL;
1374 switch (TREE_CODE (stmt))
1377 for (; !tsi_end_p (i); tsi_next (&i))
1379 stmt = tsi_stmt (i);
1380 /* If we catch all exceptions, then the body does not
1381 propagate exceptions past this point. */
1382 if (CATCH_TYPES (stmt) == NULL)
1383 this_may_throw = false;
1384 data->last_goto = NULL;
1385 remove_useless_stmts_1 (&CATCH_BODY (stmt), data);
1389 case EH_FILTER_EXPR:
1390 if (EH_FILTER_MUST_NOT_THROW (stmt))
1391 this_may_throw = false;
1392 else if (EH_FILTER_TYPES (stmt) == NULL)
1393 this_may_throw = false;
1394 remove_useless_stmts_1 (&EH_FILTER_FAILURE (stmt), data);
1398 /* Otherwise this is a cleanup. */
1399 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 1), data);
1401 /* If the cleanup is empty, then we can emit the TRY block without
1402 the enclosing TRY_CATCH_EXPR. */
1403 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 1)))
1405 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1406 data->repeat = true;
1410 data->may_throw |= this_may_throw;
1415 remove_useless_stmts_bind (tree *stmt_p, struct rus_data *data)
1419 /* First remove anything underneath the BIND_EXPR. */
1420 remove_useless_stmts_1 (&BIND_EXPR_BODY (*stmt_p), data);
1422 /* If the BIND_EXPR has no variables, then we can pull everything
1423 up one level and remove the BIND_EXPR, unless this is the toplevel
1424 BIND_EXPR for the current function or an inlined function.
1426 When this situation occurs we will want to apply this
1427 optimization again. */
1428 block = BIND_EXPR_BLOCK (*stmt_p);
1429 if (BIND_EXPR_VARS (*stmt_p) == NULL_TREE
1430 && *stmt_p != DECL_SAVED_TREE (current_function_decl)
1432 || ! BLOCK_ABSTRACT_ORIGIN (block)
1433 || (TREE_CODE (BLOCK_ABSTRACT_ORIGIN (block))
1436 *stmt_p = BIND_EXPR_BODY (*stmt_p);
1437 data->repeat = true;
1443 remove_useless_stmts_goto (tree *stmt_p, struct rus_data *data)
1445 tree dest = GOTO_DESTINATION (*stmt_p);
1447 data->may_branch = true;
1448 data->last_goto = NULL;
1450 /* Record the last goto expr, so that we can delete it if unnecessary. */
1451 if (TREE_CODE (dest) == LABEL_DECL)
1452 data->last_goto = stmt_p;
1457 remove_useless_stmts_label (tree *stmt_p, struct rus_data *data)
1459 tree label = LABEL_EXPR_LABEL (*stmt_p);
1461 data->has_label = true;
1463 /* We do want to jump across non-local label receiver code. */
1464 if (DECL_NONLOCAL (label))
1465 data->last_goto = NULL;
1467 else if (data->last_goto && GOTO_DESTINATION (*data->last_goto) == label)
1469 *data->last_goto = build_empty_stmt ();
1470 data->repeat = true;
1473 /* ??? Add something here to delete unused labels. */
1477 /* If the function is "const" or "pure", then clear TREE_SIDE_EFFECTS on its
1478 decl. This allows us to eliminate redundant or useless
1479 calls to "const" functions.
1481 Gimplifier already does the same operation, but we may notice functions
1482 being const and pure once their calls has been gimplified, so we need
1483 to update the flag. */
1486 update_call_expr_flags (tree call)
1488 tree decl = get_callee_fndecl (call);
1491 if (call_expr_flags (call) & (ECF_CONST | ECF_PURE))
1492 TREE_SIDE_EFFECTS (call) = 0;
1493 if (TREE_NOTHROW (decl))
1494 TREE_NOTHROW (call) = 1;
1498 /* T is CALL_EXPR. Set current_function_calls_* flags. */
1501 notice_special_calls (tree t)
1503 int flags = call_expr_flags (t);
1505 if (flags & ECF_MAY_BE_ALLOCA)
1506 current_function_calls_alloca = true;
1507 if (flags & ECF_RETURNS_TWICE)
1508 current_function_calls_setjmp = true;
1512 /* Clear flags set by notice_special_calls. Used by dead code removal
1513 to update the flags. */
1516 clear_special_calls (void)
1518 current_function_calls_alloca = false;
1519 current_function_calls_setjmp = false;
1524 remove_useless_stmts_1 (tree *tp, struct rus_data *data)
1528 switch (TREE_CODE (t))
1531 remove_useless_stmts_cond (tp, data);
1534 case TRY_FINALLY_EXPR:
1535 remove_useless_stmts_tf (tp, data);
1538 case TRY_CATCH_EXPR:
1539 remove_useless_stmts_tc (tp, data);
1543 remove_useless_stmts_bind (tp, data);
1547 remove_useless_stmts_goto (tp, data);
1551 remove_useless_stmts_label (tp, data);
1556 data->last_goto = NULL;
1557 data->may_branch = true;
1562 data->last_goto = NULL;
1563 notice_special_calls (t);
1564 update_call_expr_flags (t);
1565 if (tree_could_throw_p (t))
1566 data->may_throw = true;
1570 data->last_goto = NULL;
1572 op = get_call_expr_in (t);
1575 update_call_expr_flags (op);
1576 notice_special_calls (op);
1578 if (tree_could_throw_p (t))
1579 data->may_throw = true;
1582 case STATEMENT_LIST:
1584 tree_stmt_iterator i = tsi_start (t);
1585 while (!tsi_end_p (i))
1588 if (IS_EMPTY_STMT (t))
1594 remove_useless_stmts_1 (tsi_stmt_ptr (i), data);
1597 if (TREE_CODE (t) == STATEMENT_LIST)
1599 tsi_link_before (&i, t, TSI_SAME_STMT);
1609 data->last_goto = NULL;
1613 data->last_goto = NULL;
1619 remove_useless_stmts (void)
1621 struct rus_data data;
1623 clear_special_calls ();
1627 memset (&data, 0, sizeof (data));
1628 remove_useless_stmts_1 (&DECL_SAVED_TREE (current_function_decl), &data);
1630 while (data.repeat);
1634 struct tree_opt_pass pass_remove_useless_stmts =
1636 "useless", /* name */
1638 remove_useless_stmts, /* execute */
1641 0, /* static_pass_number */
1643 PROP_gimple_any, /* properties_required */
1644 0, /* properties_provided */
1645 0, /* properties_destroyed */
1646 0, /* todo_flags_start */
1647 TODO_dump_func, /* todo_flags_finish */
1652 /* Remove obviously useless statements in basic block BB. */
1655 cfg_remove_useless_stmts_bb (basic_block bb)
1657 block_stmt_iterator bsi;
1658 tree stmt = NULL_TREE;
1659 tree cond, var = NULL_TREE, val = NULL_TREE;
1660 struct var_ann_d *ann;
1662 /* Check whether we come here from a condition, and if so, get the
1664 if (EDGE_COUNT (bb->preds) != 1
1665 || !(EDGE_PRED (bb, 0)->flags & (EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
1668 cond = COND_EXPR_COND (last_stmt (EDGE_PRED (bb, 0)->src));
1670 if (TREE_CODE (cond) == VAR_DECL || TREE_CODE (cond) == PARM_DECL)
1673 val = (EDGE_PRED (bb, 0)->flags & EDGE_FALSE_VALUE
1674 ? boolean_false_node : boolean_true_node);
1676 else if (TREE_CODE (cond) == TRUTH_NOT_EXPR
1677 && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL
1678 || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL))
1680 var = TREE_OPERAND (cond, 0);
1681 val = (EDGE_PRED (bb, 0)->flags & EDGE_FALSE_VALUE
1682 ? boolean_true_node : boolean_false_node);
1686 if (EDGE_PRED (bb, 0)->flags & EDGE_FALSE_VALUE)
1687 cond = invert_truthvalue (cond);
1688 if (TREE_CODE (cond) == EQ_EXPR
1689 && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL
1690 || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL)
1691 && (TREE_CODE (TREE_OPERAND (cond, 1)) == VAR_DECL
1692 || TREE_CODE (TREE_OPERAND (cond, 1)) == PARM_DECL
1693 || TREE_CONSTANT (TREE_OPERAND (cond, 1))))
1695 var = TREE_OPERAND (cond, 0);
1696 val = TREE_OPERAND (cond, 1);
1702 /* Only work for normal local variables. */
1703 ann = var_ann (var);
1706 || TREE_ADDRESSABLE (var))
1709 if (! TREE_CONSTANT (val))
1711 ann = var_ann (val);
1714 || TREE_ADDRESSABLE (val))
1718 /* Ignore floating point variables, since comparison behaves weird for
1720 if (FLOAT_TYPE_P (TREE_TYPE (var)))
1723 for (bsi = bsi_start (bb); !bsi_end_p (bsi);)
1725 stmt = bsi_stmt (bsi);
1727 /* If the THEN/ELSE clause merely assigns a value to a variable/parameter
1728 which is already known to contain that value, then remove the useless
1729 THEN/ELSE clause. */
1730 if (TREE_CODE (stmt) == MODIFY_EXPR
1731 && TREE_OPERAND (stmt, 0) == var
1732 && operand_equal_p (val, TREE_OPERAND (stmt, 1), 0))
1738 /* Invalidate the var if we encounter something that could modify it.
1739 Likewise for the value it was previously set to. Note that we only
1740 consider values that are either a VAR_DECL or PARM_DECL so we
1741 can test for conflict very simply. */
1742 if (TREE_CODE (stmt) == ASM_EXPR
1743 || (TREE_CODE (stmt) == MODIFY_EXPR
1744 && (TREE_OPERAND (stmt, 0) == var
1745 || TREE_OPERAND (stmt, 0) == val)))
1753 /* A CFG-aware version of remove_useless_stmts. */
1756 cfg_remove_useless_stmts (void)
1760 #ifdef ENABLE_CHECKING
1761 verify_flow_info ();
1766 cfg_remove_useless_stmts_bb (bb);
1771 /* Remove PHI nodes associated with basic block BB and all edges out of BB. */
1774 remove_phi_nodes_and_edges_for_unreachable_block (basic_block bb)
1778 /* Since this block is no longer reachable, we can just delete all
1779 of its PHI nodes. */
1780 phi = phi_nodes (bb);
1783 tree next = PHI_CHAIN (phi);
1784 remove_phi_node (phi, NULL_TREE, bb);
1788 /* Remove edges to BB's successors. */
1789 while (EDGE_COUNT (bb->succs) > 0)
1790 ssa_remove_edge (EDGE_SUCC (bb, 0));
1794 /* Remove statements of basic block BB. */
1797 remove_bb (basic_block bb)
1799 block_stmt_iterator i;
1800 source_locus loc = 0;
1804 fprintf (dump_file, "Removing basic block %d\n", bb->index);
1805 if (dump_flags & TDF_DETAILS)
1807 dump_bb (bb, dump_file, 0);
1808 fprintf (dump_file, "\n");
1812 /* Remove all the instructions in the block. */
1813 for (i = bsi_start (bb); !bsi_end_p (i); bsi_remove (&i))
1815 tree stmt = bsi_stmt (i);
1816 release_defs (stmt);
1818 set_bb_for_stmt (stmt, NULL);
1820 /* Don't warn for removed gotos. Gotos are often removed due to
1821 jump threading, thus resulting in bogus warnings. Not great,
1822 since this way we lose warnings for gotos in the original
1823 program that are indeed unreachable. */
1824 if (TREE_CODE (stmt) != GOTO_EXPR && EXPR_HAS_LOCATION (stmt) && !loc)
1825 #ifdef USE_MAPPED_LOCATION
1826 loc = EXPR_LOCATION (stmt);
1828 loc = EXPR_LOCUS (stmt);
1832 /* If requested, give a warning that the first statement in the
1833 block is unreachable. We walk statements backwards in the
1834 loop above, so the last statement we process is the first statement
1836 if (warn_notreached && loc)
1837 #ifdef USE_MAPPED_LOCATION
1838 warning ("%Hwill never be executed", &loc);
1840 warning ("%Hwill never be executed", loc);
1843 remove_phi_nodes_and_edges_for_unreachable_block (bb);
1846 /* Try to remove superfluous control structures. */
1849 cleanup_control_flow (void)
1852 block_stmt_iterator bsi;
1853 bool retval = false;
1858 bsi = bsi_last (bb);
1860 if (bsi_end_p (bsi))
1863 stmt = bsi_stmt (bsi);
1864 if (TREE_CODE (stmt) == COND_EXPR
1865 || TREE_CODE (stmt) == SWITCH_EXPR)
1866 retval |= cleanup_control_expr_graph (bb, bsi);
1872 /* Disconnect an unreachable block in the control expression starting
1876 cleanup_control_expr_graph (basic_block bb, block_stmt_iterator bsi)
1879 bool retval = false;
1880 tree expr = bsi_stmt (bsi), val;
1882 if (EDGE_COUNT (bb->succs) > 1)
1887 switch (TREE_CODE (expr))
1890 val = COND_EXPR_COND (expr);
1894 val = SWITCH_COND (expr);
1895 if (TREE_CODE (val) != INTEGER_CST)
1903 taken_edge = find_taken_edge (bb, val);
1907 /* Remove all the edges except the one that is always executed. */
1908 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
1910 if (e != taken_edge)
1912 taken_edge->probability += e->probability;
1913 taken_edge->count += e->count;
1914 ssa_remove_edge (e);
1920 if (taken_edge->probability > REG_BR_PROB_BASE)
1921 taken_edge->probability = REG_BR_PROB_BASE;
1924 taken_edge = EDGE_SUCC (bb, 0);
1927 taken_edge->flags = EDGE_FALLTHRU;
1929 /* We removed some paths from the cfg. */
1930 free_dominance_info (CDI_DOMINATORS);
1936 /* Given a control block BB and a predicate VAL, return the edge that
1937 will be taken out of the block. If VAL does not match a unique
1938 edge, NULL is returned. */
1941 find_taken_edge (basic_block bb, tree val)
1945 stmt = last_stmt (bb);
1948 gcc_assert (is_ctrl_stmt (stmt));
1950 /* If VAL is a predicate of the form N RELOP N, where N is an
1951 SSA_NAME, we can usually determine its truth value. */
1952 if (val && COMPARISON_CLASS_P (val))
1955 /* If VAL is not a constant, we can't determine which edge might
1957 if (val == NULL || !really_constant_p (val))
1960 if (TREE_CODE (stmt) == COND_EXPR)
1961 return find_taken_edge_cond_expr (bb, val);
1963 if (TREE_CODE (stmt) == SWITCH_EXPR)
1964 return find_taken_edge_switch_expr (bb, val);
1966 return EDGE_SUCC (bb, 0);
1970 /* Given a constant value VAL and the entry block BB to a COND_EXPR
1971 statement, determine which of the two edges will be taken out of the
1972 block. Return NULL if either edge may be taken. */
1975 find_taken_edge_cond_expr (basic_block bb, tree val)
1977 edge true_edge, false_edge;
1979 extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
1981 /* If both edges of the branch lead to the same basic block, it doesn't
1982 matter which edge is taken. */
1983 if (true_edge->dest == false_edge->dest)
1986 /* Otherwise, try to determine which branch of the if() will be taken.
1987 If VAL is a constant but it can't be reduced to a 0 or a 1, then
1988 we don't really know which edge will be taken at runtime. This
1989 may happen when comparing addresses (e.g., if (&var1 == 4)). */
1990 if (integer_nonzerop (val))
1992 else if (integer_zerop (val))
1999 /* Given a constant value VAL and the entry block BB to a SWITCH_EXPR
2000 statement, determine which edge will be taken out of the block. Return
2001 NULL if any edge may be taken. */
2004 find_taken_edge_switch_expr (basic_block bb, tree val)
2006 tree switch_expr, taken_case;
2007 basic_block dest_bb;
2010 if (TREE_CODE (val) != INTEGER_CST)
2013 switch_expr = last_stmt (bb);
2014 taken_case = find_case_label_for_value (switch_expr, val);
2015 dest_bb = label_to_block (CASE_LABEL (taken_case));
2017 e = find_edge (bb, dest_bb);
2023 /* Return the CASE_LABEL_EXPR that SWITCH_EXPR will take for VAL.
2024 We can make optimal use here of the fact that the case labels are
2025 sorted: We can do a binary search for a case matching VAL. */
2028 find_case_label_for_value (tree switch_expr, tree val)
2030 tree vec = SWITCH_LABELS (switch_expr);
2031 size_t low, high, n = TREE_VEC_LENGTH (vec);
2032 tree default_case = TREE_VEC_ELT (vec, n - 1);
2034 for (low = -1, high = n - 1; high - low > 1; )
2036 size_t i = (high + low) / 2;
2037 tree t = TREE_VEC_ELT (vec, i);
2040 /* Cache the result of comparing CASE_LOW and val. */
2041 cmp = tree_int_cst_compare (CASE_LOW (t), val);
2048 if (CASE_HIGH (t) == NULL)
2050 /* A singe-valued case label. */
2056 /* A case range. We can only handle integer ranges. */
2057 if (cmp <= 0 && tree_int_cst_compare (CASE_HIGH (t), val) >= 0)
2062 return default_case;
2066 /* If all the PHI nodes in DEST have alternatives for E1 and E2 and
2067 those alternatives are equal in each of the PHI nodes, then return
2068 true, else return false. */
2071 phi_alternatives_equal (basic_block dest, edge e1, edge e2)
2073 tree phi, val1, val2;
2076 for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi))
2078 n1 = phi_arg_from_edge (phi, e1);
2079 n2 = phi_arg_from_edge (phi, e2);
2081 gcc_assert (n1 >= 0);
2082 gcc_assert (n2 >= 0);
2084 val1 = PHI_ARG_DEF (phi, n1);
2085 val2 = PHI_ARG_DEF (phi, n2);
2087 if (!operand_equal_p (val1, val2, 0))
2095 /*---------------------------------------------------------------------------
2097 ---------------------------------------------------------------------------*/
2099 /* Dump tree-specific information of block BB to file OUTF. */
2102 tree_dump_bb (basic_block bb, FILE *outf, int indent)
2104 dump_generic_bb (outf, bb, indent, TDF_VOPS);
2108 /* Dump a basic block on stderr. */
2111 debug_tree_bb (basic_block bb)
2113 dump_bb (bb, stderr, 0);
2117 /* Dump basic block with index N on stderr. */
2120 debug_tree_bb_n (int n)
2122 debug_tree_bb (BASIC_BLOCK (n));
2123 return BASIC_BLOCK (n);
2127 /* Dump the CFG on stderr.
2129 FLAGS are the same used by the tree dumping functions
2130 (see TDF_* in tree.h). */
2133 debug_tree_cfg (int flags)
2135 dump_tree_cfg (stderr, flags);
2139 /* Dump the program showing basic block boundaries on the given FILE.
2141 FLAGS are the same used by the tree dumping functions (see TDF_* in
2145 dump_tree_cfg (FILE *file, int flags)
2147 if (flags & TDF_DETAILS)
2149 const char *funcname
2150 = lang_hooks.decl_printable_name (current_function_decl, 2);
2153 fprintf (file, ";; Function %s\n\n", funcname);
2154 fprintf (file, ";; \n%d basic blocks, %d edges, last basic block %d.\n\n",
2155 n_basic_blocks, n_edges, last_basic_block);
2157 brief_dump_cfg (file);
2158 fprintf (file, "\n");
2161 if (flags & TDF_STATS)
2162 dump_cfg_stats (file);
2164 dump_function_to_file (current_function_decl, file, flags | TDF_BLOCKS);
2168 /* Dump CFG statistics on FILE. */
2171 dump_cfg_stats (FILE *file)
2173 static long max_num_merged_labels = 0;
2174 unsigned long size, total = 0;
2177 const char * const fmt_str = "%-30s%-13s%12s\n";
2178 const char * const fmt_str_1 = "%-30s%13d%11lu%c\n";
2179 const char * const fmt_str_3 = "%-43s%11lu%c\n";
2180 const char *funcname
2181 = lang_hooks.decl_printable_name (current_function_decl, 2);
2184 fprintf (file, "\nCFG Statistics for %s\n\n", funcname);
2186 fprintf (file, "---------------------------------------------------------\n");
2187 fprintf (file, fmt_str, "", " Number of ", "Memory");
2188 fprintf (file, fmt_str, "", " instances ", "used ");
2189 fprintf (file, "---------------------------------------------------------\n");
2191 size = n_basic_blocks * sizeof (struct basic_block_def);
2193 fprintf (file, fmt_str_1, "Basic blocks", n_basic_blocks,
2194 SCALE (size), LABEL (size));
2198 n_edges += EDGE_COUNT (bb->succs);
2199 size = n_edges * sizeof (struct edge_def);
2201 fprintf (file, fmt_str_1, "Edges", n_edges, SCALE (size), LABEL (size));
2203 size = n_basic_blocks * sizeof (struct bb_ann_d);
2205 fprintf (file, fmt_str_1, "Basic block annotations", n_basic_blocks,
2206 SCALE (size), LABEL (size));
2208 fprintf (file, "---------------------------------------------------------\n");
2209 fprintf (file, fmt_str_3, "Total memory used by CFG data", SCALE (total),
2211 fprintf (file, "---------------------------------------------------------\n");
2212 fprintf (file, "\n");
2214 if (cfg_stats.num_merged_labels > max_num_merged_labels)
2215 max_num_merged_labels = cfg_stats.num_merged_labels;
2217 fprintf (file, "Coalesced label blocks: %ld (Max so far: %ld)\n",
2218 cfg_stats.num_merged_labels, max_num_merged_labels);
2220 fprintf (file, "\n");
2224 /* Dump CFG statistics on stderr. Keep extern so that it's always
2225 linked in the final executable. */
2228 debug_cfg_stats (void)
2230 dump_cfg_stats (stderr);
2234 /* Dump the flowgraph to a .vcg FILE. */
2237 tree_cfg2vcg (FILE *file)
2242 const char *funcname
2243 = lang_hooks.decl_printable_name (current_function_decl, 2);
2245 /* Write the file header. */
2246 fprintf (file, "graph: { title: \"%s\"\n", funcname);
2247 fprintf (file, "node: { title: \"ENTRY\" label: \"ENTRY\" }\n");
2248 fprintf (file, "node: { title: \"EXIT\" label: \"EXIT\" }\n");
2250 /* Write blocks and edges. */
2251 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
2253 fprintf (file, "edge: { sourcename: \"ENTRY\" targetname: \"%d\"",
2256 if (e->flags & EDGE_FAKE)
2257 fprintf (file, " linestyle: dotted priority: 10");
2259 fprintf (file, " linestyle: solid priority: 100");
2261 fprintf (file, " }\n");
2267 enum tree_code head_code, end_code;
2268 const char *head_name, *end_name;
2271 tree first = first_stmt (bb);
2272 tree last = last_stmt (bb);
2276 head_code = TREE_CODE (first);
2277 head_name = tree_code_name[head_code];
2278 head_line = get_lineno (first);
2281 head_name = "no-statement";
2285 end_code = TREE_CODE (last);
2286 end_name = tree_code_name[end_code];
2287 end_line = get_lineno (last);
2290 end_name = "no-statement";
2292 fprintf (file, "node: { title: \"%d\" label: \"#%d\\n%s (%d)\\n%s (%d)\"}\n",
2293 bb->index, bb->index, head_name, head_line, end_name,
2296 FOR_EACH_EDGE (e, ei, bb->succs)
2298 if (e->dest == EXIT_BLOCK_PTR)
2299 fprintf (file, "edge: { sourcename: \"%d\" targetname: \"EXIT\"", bb->index);
2301 fprintf (file, "edge: { sourcename: \"%d\" targetname: \"%d\"", bb->index, e->dest->index);
2303 if (e->flags & EDGE_FAKE)
2304 fprintf (file, " priority: 10 linestyle: dotted");
2306 fprintf (file, " priority: 100 linestyle: solid");
2308 fprintf (file, " }\n");
2311 if (bb->next_bb != EXIT_BLOCK_PTR)
2315 fputs ("}\n\n", file);
2320 /*---------------------------------------------------------------------------
2321 Miscellaneous helpers
2322 ---------------------------------------------------------------------------*/
2324 /* Return true if T represents a stmt that always transfers control. */
2327 is_ctrl_stmt (tree t)
2329 return (TREE_CODE (t) == COND_EXPR
2330 || TREE_CODE (t) == SWITCH_EXPR
2331 || TREE_CODE (t) == GOTO_EXPR
2332 || TREE_CODE (t) == RETURN_EXPR
2333 || TREE_CODE (t) == RESX_EXPR);
2337 /* Return true if T is a statement that may alter the flow of control
2338 (e.g., a call to a non-returning function). */
2341 is_ctrl_altering_stmt (tree t)
2346 call = get_call_expr_in (t);
2349 /* A non-pure/const CALL_EXPR alters flow control if the current
2350 function has nonlocal labels. */
2351 if (TREE_SIDE_EFFECTS (call) && current_function_has_nonlocal_label)
2354 /* A CALL_EXPR also alters control flow if it does not return. */
2355 if (call_expr_flags (call) & (ECF_NORETURN | ECF_LONGJMP))
2359 /* If a statement can throw, it alters control flow. */
2360 return tree_can_throw_internal (t);
2364 /* Return true if T is a computed goto. */
2367 computed_goto_p (tree t)
2369 return (TREE_CODE (t) == GOTO_EXPR
2370 && TREE_CODE (GOTO_DESTINATION (t)) != LABEL_DECL);
2374 /* Checks whether EXPR is a simple local goto. */
2377 simple_goto_p (tree expr)
2379 return (TREE_CODE (expr) == GOTO_EXPR
2380 && TREE_CODE (GOTO_DESTINATION (expr)) == LABEL_DECL);
2384 /* Return true if T should start a new basic block. PREV_T is the
2385 statement preceding T. It is used when T is a label or a case label.
2386 Labels should only start a new basic block if their previous statement
2387 wasn't a label. Otherwise, sequence of labels would generate
2388 unnecessary basic blocks that only contain a single label. */
2391 stmt_starts_bb_p (tree t, tree prev_t)
2393 enum tree_code code;
2398 /* LABEL_EXPRs start a new basic block only if the preceding
2399 statement wasn't a label of the same type. This prevents the
2400 creation of consecutive blocks that have nothing but a single
2402 code = TREE_CODE (t);
2403 if (code == LABEL_EXPR)
2405 /* Nonlocal and computed GOTO targets always start a new block. */
2406 if (code == LABEL_EXPR
2407 && (DECL_NONLOCAL (LABEL_EXPR_LABEL (t))
2408 || FORCED_LABEL (LABEL_EXPR_LABEL (t))))
2411 if (prev_t && TREE_CODE (prev_t) == code)
2413 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (prev_t)))
2416 cfg_stats.num_merged_labels++;
2427 /* Return true if T should end a basic block. */
2430 stmt_ends_bb_p (tree t)
2432 return is_ctrl_stmt (t) || is_ctrl_altering_stmt (t);
2436 /* Add gotos that used to be represented implicitly in the CFG. */
2439 disband_implicit_edges (void)
2442 block_stmt_iterator last;
2449 last = bsi_last (bb);
2450 stmt = last_stmt (bb);
2452 if (stmt && TREE_CODE (stmt) == COND_EXPR)
2454 /* Remove superfluous gotos from COND_EXPR branches. Moved
2455 from cfg_remove_useless_stmts here since it violates the
2456 invariants for tree--cfg correspondence and thus fits better
2457 here where we do it anyway. */
2458 FOR_EACH_EDGE (e, ei, bb->succs)
2460 if (e->dest != bb->next_bb)
2463 if (e->flags & EDGE_TRUE_VALUE)
2464 COND_EXPR_THEN (stmt) = build_empty_stmt ();
2465 else if (e->flags & EDGE_FALSE_VALUE)
2466 COND_EXPR_ELSE (stmt) = build_empty_stmt ();
2469 e->flags |= EDGE_FALLTHRU;
2475 if (stmt && TREE_CODE (stmt) == RETURN_EXPR)
2477 /* Remove the RETURN_EXPR if we may fall though to the exit
2479 gcc_assert (EDGE_COUNT (bb->succs) == 1);
2480 gcc_assert (EDGE_SUCC (bb, 0)->dest == EXIT_BLOCK_PTR);
2482 if (bb->next_bb == EXIT_BLOCK_PTR
2483 && !TREE_OPERAND (stmt, 0))
2486 EDGE_SUCC (bb, 0)->flags |= EDGE_FALLTHRU;
2491 /* There can be no fallthru edge if the last statement is a control
2493 if (stmt && is_ctrl_stmt (stmt))
2496 /* Find a fallthru edge and emit the goto if necessary. */
2497 FOR_EACH_EDGE (e, ei, bb->succs)
2498 if (e->flags & EDGE_FALLTHRU)
2501 if (!e || e->dest == bb->next_bb)
2504 gcc_assert (e->dest != EXIT_BLOCK_PTR);
2505 label = tree_block_label (e->dest);
2507 stmt = build1 (GOTO_EXPR, void_type_node, label);
2508 #ifdef USE_MAPPED_LOCATION
2509 SET_EXPR_LOCATION (stmt, e->goto_locus);
2511 SET_EXPR_LOCUS (stmt, e->goto_locus);
2513 bsi_insert_after (&last, stmt, BSI_NEW_STMT);
2514 e->flags &= ~EDGE_FALLTHRU;
2518 /* Remove block annotations and other datastructures. */
2521 delete_tree_cfg_annotations (void)
2524 if (n_basic_blocks > 0)
2525 free_blocks_annotations ();
2527 label_to_block_map = NULL;
2534 /* Return the first statement in basic block BB. */
2537 first_stmt (basic_block bb)
2539 block_stmt_iterator i = bsi_start (bb);
2540 return !bsi_end_p (i) ? bsi_stmt (i) : NULL_TREE;
2544 /* Return the last statement in basic block BB. */
2547 last_stmt (basic_block bb)
2549 block_stmt_iterator b = bsi_last (bb);
2550 return !bsi_end_p (b) ? bsi_stmt (b) : NULL_TREE;
2554 /* Return a pointer to the last statement in block BB. */
2557 last_stmt_ptr (basic_block bb)
2559 block_stmt_iterator last = bsi_last (bb);
2560 return !bsi_end_p (last) ? bsi_stmt_ptr (last) : NULL;
2564 /* Return the last statement of an otherwise empty block. Return NULL
2565 if the block is totally empty, or if it contains more than one
2569 last_and_only_stmt (basic_block bb)
2571 block_stmt_iterator i = bsi_last (bb);
2577 last = bsi_stmt (i);
2582 /* Empty statements should no longer appear in the instruction stream.
2583 Everything that might have appeared before should be deleted by
2584 remove_useless_stmts, and the optimizers should just bsi_remove
2585 instead of smashing with build_empty_stmt.
2587 Thus the only thing that should appear here in a block containing
2588 one executable statement is a label. */
2589 prev = bsi_stmt (i);
2590 if (TREE_CODE (prev) == LABEL_EXPR)
2597 /* Mark BB as the basic block holding statement T. */
2600 set_bb_for_stmt (tree t, basic_block bb)
2602 if (TREE_CODE (t) == PHI_NODE)
2604 else if (TREE_CODE (t) == STATEMENT_LIST)
2606 tree_stmt_iterator i;
2607 for (i = tsi_start (t); !tsi_end_p (i); tsi_next (&i))
2608 set_bb_for_stmt (tsi_stmt (i), bb);
2612 stmt_ann_t ann = get_stmt_ann (t);
2615 /* If the statement is a label, add the label to block-to-labels map
2616 so that we can speed up edge creation for GOTO_EXPRs. */
2617 if (TREE_CODE (t) == LABEL_EXPR)
2621 t = LABEL_EXPR_LABEL (t);
2622 uid = LABEL_DECL_UID (t);
2625 LABEL_DECL_UID (t) = uid = cfun->last_label_uid++;
2626 if (VARRAY_SIZE (label_to_block_map) <= (unsigned) uid)
2627 VARRAY_GROW (label_to_block_map, 3 * uid / 2);
2630 /* We're moving an existing label. Make sure that we've
2631 removed it from the old block. */
2632 gcc_assert (!bb || !VARRAY_BB (label_to_block_map, uid));
2633 VARRAY_BB (label_to_block_map, uid) = bb;
2638 /* Finds iterator for STMT. */
2640 extern block_stmt_iterator
2641 bsi_for_stmt (tree stmt)
2643 block_stmt_iterator bsi;
2645 for (bsi = bsi_start (bb_for_stmt (stmt)); !bsi_end_p (bsi); bsi_next (&bsi))
2646 if (bsi_stmt (bsi) == stmt)
2652 /* Insert statement (or statement list) T before the statement
2653 pointed-to by iterator I. M specifies how to update iterator I
2654 after insertion (see enum bsi_iterator_update). */
2657 bsi_insert_before (block_stmt_iterator *i, tree t, enum bsi_iterator_update m)
2659 set_bb_for_stmt (t, i->bb);
2660 tsi_link_before (&i->tsi, t, m);
2665 /* Insert statement (or statement list) T after the statement
2666 pointed-to by iterator I. M specifies how to update iterator I
2667 after insertion (see enum bsi_iterator_update). */
2670 bsi_insert_after (block_stmt_iterator *i, tree t, enum bsi_iterator_update m)
2672 set_bb_for_stmt (t, i->bb);
2673 tsi_link_after (&i->tsi, t, m);
2678 /* Remove the statement pointed to by iterator I. The iterator is updated
2679 to the next statement. */
2682 bsi_remove (block_stmt_iterator *i)
2684 tree t = bsi_stmt (*i);
2685 set_bb_for_stmt (t, NULL);
2686 tsi_delink (&i->tsi);
2690 /* Move the statement at FROM so it comes right after the statement at TO. */
2693 bsi_move_after (block_stmt_iterator *from, block_stmt_iterator *to)
2695 tree stmt = bsi_stmt (*from);
2697 bsi_insert_after (to, stmt, BSI_SAME_STMT);
2701 /* Move the statement at FROM so it comes right before the statement at TO. */
2704 bsi_move_before (block_stmt_iterator *from, block_stmt_iterator *to)
2706 tree stmt = bsi_stmt (*from);
2708 bsi_insert_before (to, stmt, BSI_SAME_STMT);
2712 /* Move the statement at FROM to the end of basic block BB. */
2715 bsi_move_to_bb_end (block_stmt_iterator *from, basic_block bb)
2717 block_stmt_iterator last = bsi_last (bb);
2719 /* Have to check bsi_end_p because it could be an empty block. */
2720 if (!bsi_end_p (last) && is_ctrl_stmt (bsi_stmt (last)))
2721 bsi_move_before (from, &last);
2723 bsi_move_after (from, &last);
2727 /* Replace the contents of the statement pointed to by iterator BSI
2728 with STMT. If PRESERVE_EH_INFO is true, the exception handling
2729 information of the original statement is preserved. */
2732 bsi_replace (const block_stmt_iterator *bsi, tree stmt, bool preserve_eh_info)
2735 tree orig_stmt = bsi_stmt (*bsi);
2737 SET_EXPR_LOCUS (stmt, EXPR_LOCUS (orig_stmt));
2738 set_bb_for_stmt (stmt, bsi->bb);
2740 /* Preserve EH region information from the original statement, if
2741 requested by the caller. */
2742 if (preserve_eh_info)
2744 eh_region = lookup_stmt_eh_region (orig_stmt);
2746 add_stmt_to_eh_region (stmt, eh_region);
2749 *bsi_stmt_ptr (*bsi) = stmt;
2754 /* Insert the statement pointed-to by BSI into edge E. Every attempt
2755 is made to place the statement in an existing basic block, but
2756 sometimes that isn't possible. When it isn't possible, the edge is
2757 split and the statement is added to the new block.
2759 In all cases, the returned *BSI points to the correct location. The
2760 return value is true if insertion should be done after the location,
2761 or false if it should be done before the location. If new basic block
2762 has to be created, it is stored in *NEW_BB. */
2765 tree_find_edge_insert_loc (edge e, block_stmt_iterator *bsi,
2766 basic_block *new_bb)
2768 basic_block dest, src;
2774 /* If the destination has one predecessor which has no PHI nodes,
2775 insert there. Except for the exit block.
2777 The requirement for no PHI nodes could be relaxed. Basically we
2778 would have to examine the PHIs to prove that none of them used
2779 the value set by the statement we want to insert on E. That
2780 hardly seems worth the effort. */
2781 if (EDGE_COUNT (dest->preds) == 1
2782 && ! phi_nodes (dest)
2783 && dest != EXIT_BLOCK_PTR)
2785 *bsi = bsi_start (dest);
2786 if (bsi_end_p (*bsi))
2789 /* Make sure we insert after any leading labels. */
2790 tmp = bsi_stmt (*bsi);
2791 while (TREE_CODE (tmp) == LABEL_EXPR)
2794 if (bsi_end_p (*bsi))
2796 tmp = bsi_stmt (*bsi);
2799 if (bsi_end_p (*bsi))
2801 *bsi = bsi_last (dest);
2808 /* If the source has one successor, the edge is not abnormal and
2809 the last statement does not end a basic block, insert there.
2810 Except for the entry block. */
2812 if ((e->flags & EDGE_ABNORMAL) == 0
2813 && EDGE_COUNT (src->succs) == 1
2814 && src != ENTRY_BLOCK_PTR)
2816 *bsi = bsi_last (src);
2817 if (bsi_end_p (*bsi))
2820 tmp = bsi_stmt (*bsi);
2821 if (!stmt_ends_bb_p (tmp))
2824 /* Insert code just before returning the value. We may need to decompose
2825 the return in the case it contains non-trivial operand. */
2826 if (TREE_CODE (tmp) == RETURN_EXPR)
2828 tree op = TREE_OPERAND (tmp, 0);
2829 if (!is_gimple_val (op))
2831 gcc_assert (TREE_CODE (op) == MODIFY_EXPR);
2832 bsi_insert_before (bsi, op, BSI_NEW_STMT);
2833 TREE_OPERAND (tmp, 0) = TREE_OPERAND (op, 0);
2840 /* Otherwise, create a new basic block, and split this edge. */
2841 dest = split_edge (e);
2844 e = EDGE_PRED (dest, 0);
2849 /* This routine will commit all pending edge insertions, creating any new
2850 basic blocks which are necessary.
2852 If specified, NEW_BLOCKS returns a count of the number of new basic
2853 blocks which were created. */
2856 bsi_commit_edge_inserts (int *new_blocks)
2863 blocks = n_basic_blocks;
2865 bsi_commit_edge_inserts_1 (EDGE_SUCC (ENTRY_BLOCK_PTR, 0));
2868 FOR_EACH_EDGE (e, ei, bb->succs)
2869 bsi_commit_edge_inserts_1 (e);
2872 *new_blocks = n_basic_blocks - blocks;
2876 /* Commit insertions pending at edge E. */
2879 bsi_commit_edge_inserts_1 (edge e)
2881 if (PENDING_STMT (e))
2883 block_stmt_iterator bsi;
2884 tree stmt = PENDING_STMT (e);
2886 PENDING_STMT (e) = NULL_TREE;
2888 if (tree_find_edge_insert_loc (e, &bsi, NULL))
2889 bsi_insert_after (&bsi, stmt, BSI_NEW_STMT);
2891 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
2896 /* Add STMT to the pending list of edge E. No actual insertion is
2897 made until a call to bsi_commit_edge_inserts () is made. */
2900 bsi_insert_on_edge (edge e, tree stmt)
2902 append_to_statement_list (stmt, &PENDING_STMT (e));
2905 /* Similar to bsi_insert_on_edge+bsi_commit_edge_inserts. If new block has to
2906 be created, it is returned. */
2909 bsi_insert_on_edge_immediate (edge e, tree stmt)
2911 block_stmt_iterator bsi;
2912 basic_block new_bb = NULL;
2914 gcc_assert (!PENDING_STMT (e));
2916 if (tree_find_edge_insert_loc (e, &bsi, &new_bb))
2917 bsi_insert_after (&bsi, stmt, BSI_NEW_STMT);
2919 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
2924 /*---------------------------------------------------------------------------
2925 Tree specific functions for CFG manipulation
2926 ---------------------------------------------------------------------------*/
2928 /* Split a (typically critical) edge EDGE_IN. Return the new block.
2929 Abort on abnormal edges. */
2932 tree_split_edge (edge edge_in)
2934 basic_block new_bb, after_bb, dest, src;
2940 /* Abnormal edges cannot be split. */
2941 gcc_assert (!(edge_in->flags & EDGE_ABNORMAL));
2944 dest = edge_in->dest;
2946 /* Place the new block in the block list. Try to keep the new block
2947 near its "logical" location. This is of most help to humans looking
2948 at debugging dumps. */
2949 FOR_EACH_EDGE (e, ei, dest->preds)
2950 if (e->src->next_bb == dest)
2953 after_bb = dest->prev_bb;
2955 after_bb = edge_in->src;
2957 new_bb = create_empty_bb (after_bb);
2958 new_bb->frequency = EDGE_FREQUENCY (edge_in);
2959 new_bb->count = edge_in->count;
2960 new_edge = make_edge (new_bb, dest, EDGE_FALLTHRU);
2961 new_edge->probability = REG_BR_PROB_BASE;
2962 new_edge->count = edge_in->count;
2964 /* Find all the PHI arguments on the original edge, and change them to
2965 the new edge. Do it before redirection, so that the argument does not
2967 for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi))
2969 num_elem = PHI_NUM_ARGS (phi);
2970 for (i = 0; i < num_elem; i++)
2971 if (PHI_ARG_EDGE (phi, i) == edge_in)
2973 PHI_ARG_EDGE (phi, i) = new_edge;
2978 e = redirect_edge_and_branch (edge_in, new_bb);
2980 gcc_assert (!PENDING_STMT (edge_in));
2986 /* Return true when BB has label LABEL in it. */
2989 has_label_p (basic_block bb, tree label)
2991 block_stmt_iterator bsi;
2993 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
2995 tree stmt = bsi_stmt (bsi);
2997 if (TREE_CODE (stmt) != LABEL_EXPR)
2999 if (LABEL_EXPR_LABEL (stmt) == label)
3006 /* Callback for walk_tree, check that all elements with address taken are
3007 properly noticed as such. */
3010 verify_expr (tree *tp, int *walk_subtrees, void *data ATTRIBUTE_UNUSED)
3017 /* Check operand N for being valid GIMPLE and give error MSG if not.
3018 We check for constants explicitly since they are not considered
3019 gimple invariants if they overflowed. */
3020 #define CHECK_OP(N, MSG) \
3021 do { if (!CONSTANT_CLASS_P (TREE_OPERAND (t, N)) \
3022 && !is_gimple_val (TREE_OPERAND (t, N))) \
3023 { error (MSG); return TREE_OPERAND (t, N); }} while (0)
3025 switch (TREE_CODE (t))
3028 if (SSA_NAME_IN_FREE_LIST (t))
3030 error ("SSA name in freelist but still referenced");
3036 x = TREE_OPERAND (t, 0);
3037 if (TREE_CODE (x) == BIT_FIELD_REF
3038 && is_gimple_reg (TREE_OPERAND (x, 0)))
3040 error ("GIMPLE register modified with BIT_FIELD_REF");
3046 /* Skip any references (they will be checked when we recurse down the
3047 tree) and ensure that any variable used as a prefix is marked
3049 for (x = TREE_OPERAND (t, 0);
3050 (handled_component_p (x)
3051 || TREE_CODE (x) == REALPART_EXPR
3052 || TREE_CODE (x) == IMAGPART_EXPR);
3053 x = TREE_OPERAND (x, 0))
3056 if (TREE_CODE (x) != VAR_DECL && TREE_CODE (x) != PARM_DECL)
3058 if (!TREE_ADDRESSABLE (x))
3060 error ("address taken, but ADDRESSABLE bit not set");
3066 x = TREE_OPERAND (t, 0);
3067 if (TREE_CODE (TREE_TYPE (x)) != BOOLEAN_TYPE)
3069 error ("non-boolean used in condition");
3076 case FIX_TRUNC_EXPR:
3078 case FIX_FLOOR_EXPR:
3079 case FIX_ROUND_EXPR:
3084 case NON_LVALUE_EXPR:
3085 case TRUTH_NOT_EXPR:
3086 CHECK_OP (0, "Invalid operand to unary operator");
3093 case ARRAY_RANGE_REF:
3095 case VIEW_CONVERT_EXPR:
3096 /* We have a nest of references. Verify that each of the operands
3097 that determine where to reference is either a constant or a variable,
3098 verify that the base is valid, and then show we've already checked
3100 while (TREE_CODE (t) == REALPART_EXPR || TREE_CODE (t) == IMAGPART_EXPR
3101 || handled_component_p (t))
3103 if (TREE_CODE (t) == COMPONENT_REF && TREE_OPERAND (t, 2))
3104 CHECK_OP (2, "Invalid COMPONENT_REF offset operator");
3105 else if (TREE_CODE (t) == ARRAY_REF
3106 || TREE_CODE (t) == ARRAY_RANGE_REF)
3108 CHECK_OP (1, "Invalid array index.");
3109 if (TREE_OPERAND (t, 2))
3110 CHECK_OP (2, "Invalid array lower bound.");
3111 if (TREE_OPERAND (t, 3))
3112 CHECK_OP (3, "Invalid array stride.");
3114 else if (TREE_CODE (t) == BIT_FIELD_REF)
3116 CHECK_OP (1, "Invalid operand to BIT_FIELD_REF");
3117 CHECK_OP (2, "Invalid operand to BIT_FIELD_REF");
3120 t = TREE_OPERAND (t, 0);
3123 if (!CONSTANT_CLASS_P (t) && !is_gimple_lvalue (t))
3125 error ("Invalid reference prefix.");
3137 case UNORDERED_EXPR:
3148 case TRUNC_DIV_EXPR:
3150 case FLOOR_DIV_EXPR:
3151 case ROUND_DIV_EXPR:
3152 case TRUNC_MOD_EXPR:
3154 case FLOOR_MOD_EXPR:
3155 case ROUND_MOD_EXPR:
3157 case EXACT_DIV_EXPR:
3167 CHECK_OP (0, "Invalid operand to binary operator");
3168 CHECK_OP (1, "Invalid operand to binary operator");
3180 /* Verify STMT, return true if STMT is not in GIMPLE form.
3181 TODO: Implement type checking. */
3184 verify_stmt (tree stmt, bool last_in_block)
3188 if (!is_gimple_stmt (stmt))
3190 error ("Is not a valid GIMPLE statement.");
3194 addr = walk_tree (&stmt, verify_expr, NULL, NULL);
3197 debug_generic_stmt (addr);
3201 /* If the statement is marked as part of an EH region, then it is
3202 expected that the statement could throw. Verify that when we
3203 have optimizations that simplify statements such that we prove
3204 that they cannot throw, that we update other data structures
3206 if (lookup_stmt_eh_region (stmt) >= 0)
3208 if (!tree_could_throw_p (stmt))
3210 error ("Statement marked for throw, but doesn%'t.");
3213 if (!last_in_block && tree_can_throw_internal (stmt))
3215 error ("Statement marked for throw in middle of block.");
3223 debug_generic_stmt (stmt);
3228 /* Return true when the T can be shared. */
3231 tree_node_can_be_shared (tree t)
3233 if (IS_TYPE_OR_DECL_P (t)
3234 /* We check for constants explicitly since they are not considered
3235 gimple invariants if they overflowed. */
3236 || CONSTANT_CLASS_P (t)
3237 || is_gimple_min_invariant (t)
3238 || TREE_CODE (t) == SSA_NAME)
3241 while (((TREE_CODE (t) == ARRAY_REF || TREE_CODE (t) == ARRAY_RANGE_REF)
3242 /* We check for constants explicitly since they are not considered
3243 gimple invariants if they overflowed. */
3244 && (CONSTANT_CLASS_P (TREE_OPERAND (t, 1))
3245 || is_gimple_min_invariant (TREE_OPERAND (t, 1))))
3246 || (TREE_CODE (t) == COMPONENT_REF
3247 || TREE_CODE (t) == REALPART_EXPR
3248 || TREE_CODE (t) == IMAGPART_EXPR))
3249 t = TREE_OPERAND (t, 0);
3258 /* Called via walk_trees. Verify tree sharing. */
3261 verify_node_sharing (tree * tp, int *walk_subtrees, void *data)
3263 htab_t htab = (htab_t) data;
3266 if (tree_node_can_be_shared (*tp))
3268 *walk_subtrees = false;
3272 slot = htab_find_slot (htab, *tp, INSERT);
3281 /* Verify the GIMPLE statement chain. */
3287 block_stmt_iterator bsi;
3292 timevar_push (TV_TREE_STMT_VERIFY);
3293 htab = htab_create (37, htab_hash_pointer, htab_eq_pointer, NULL);
3300 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
3302 int phi_num_args = PHI_NUM_ARGS (phi);
3304 for (i = 0; i < phi_num_args; i++)
3306 tree t = PHI_ARG_DEF (phi, i);
3309 /* Addressable variables do have SSA_NAMEs but they
3310 are not considered gimple values. */
3311 if (TREE_CODE (t) != SSA_NAME
3312 && TREE_CODE (t) != FUNCTION_DECL
3313 && !is_gimple_val (t))
3315 error ("PHI def is not a GIMPLE value");
3316 debug_generic_stmt (phi);
3317 debug_generic_stmt (t);
3321 addr = walk_tree (&t, verify_expr, NULL, NULL);
3324 debug_generic_stmt (addr);
3328 addr = walk_tree (&t, verify_node_sharing, htab, NULL);
3331 error ("Incorrect sharing of tree nodes");
3332 debug_generic_stmt (phi);
3333 debug_generic_stmt (addr);
3339 for (bsi = bsi_start (bb); !bsi_end_p (bsi); )
3341 tree stmt = bsi_stmt (bsi);
3343 err |= verify_stmt (stmt, bsi_end_p (bsi));
3344 addr = walk_tree (&stmt, verify_node_sharing, htab, NULL);
3347 error ("Incorrect sharing of tree nodes");
3348 debug_generic_stmt (stmt);
3349 debug_generic_stmt (addr);
3356 internal_error ("verify_stmts failed.");
3359 timevar_pop (TV_TREE_STMT_VERIFY);
3363 /* Verifies that the flow information is OK. */
3366 tree_verify_flow_info (void)
3370 block_stmt_iterator bsi;
3375 if (ENTRY_BLOCK_PTR->stmt_list)
3377 error ("ENTRY_BLOCK has a statement list associated with it\n");
3381 if (EXIT_BLOCK_PTR->stmt_list)
3383 error ("EXIT_BLOCK has a statement list associated with it\n");
3387 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
3388 if (e->flags & EDGE_FALLTHRU)
3390 error ("Fallthru to exit from bb %d\n", e->src->index);
3396 bool found_ctrl_stmt = false;
3398 /* Skip labels on the start of basic block. */
3399 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3401 if (TREE_CODE (bsi_stmt (bsi)) != LABEL_EXPR)
3404 if (label_to_block (LABEL_EXPR_LABEL (bsi_stmt (bsi))) != bb)
3406 error ("Label %s to block does not match in bb %d\n",
3407 IDENTIFIER_POINTER (DECL_NAME (bsi_stmt (bsi))),
3412 if (decl_function_context (LABEL_EXPR_LABEL (bsi_stmt (bsi)))
3413 != current_function_decl)
3415 error ("Label %s has incorrect context in bb %d\n",
3416 IDENTIFIER_POINTER (DECL_NAME (bsi_stmt (bsi))),
3422 /* Verify that body of basic block BB is free of control flow. */
3423 for (; !bsi_end_p (bsi); bsi_next (&bsi))
3425 tree stmt = bsi_stmt (bsi);
3427 if (found_ctrl_stmt)
3429 error ("Control flow in the middle of basic block %d\n",
3434 if (stmt_ends_bb_p (stmt))
3435 found_ctrl_stmt = true;
3437 if (TREE_CODE (stmt) == LABEL_EXPR)
3439 error ("Label %s in the middle of basic block %d\n",
3440 IDENTIFIER_POINTER (DECL_NAME (stmt)),
3445 bsi = bsi_last (bb);
3446 if (bsi_end_p (bsi))
3449 stmt = bsi_stmt (bsi);
3451 if (is_ctrl_stmt (stmt))
3453 FOR_EACH_EDGE (e, ei, bb->succs)
3454 if (e->flags & EDGE_FALLTHRU)
3456 error ("Fallthru edge after a control statement in bb %d \n",
3462 switch (TREE_CODE (stmt))
3468 if (TREE_CODE (COND_EXPR_THEN (stmt)) != GOTO_EXPR
3469 || TREE_CODE (COND_EXPR_ELSE (stmt)) != GOTO_EXPR)
3471 error ("Structured COND_EXPR at the end of bb %d\n", bb->index);
3475 extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
3477 if (!true_edge || !false_edge
3478 || !(true_edge->flags & EDGE_TRUE_VALUE)
3479 || !(false_edge->flags & EDGE_FALSE_VALUE)
3480 || (true_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL))
3481 || (false_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL))
3482 || EDGE_COUNT (bb->succs) >= 3)
3484 error ("Wrong outgoing edge flags at end of bb %d\n",
3489 if (!has_label_p (true_edge->dest,
3490 GOTO_DESTINATION (COND_EXPR_THEN (stmt))))
3492 error ("%<then%> label does not match edge at end of bb %d\n",
3497 if (!has_label_p (false_edge->dest,
3498 GOTO_DESTINATION (COND_EXPR_ELSE (stmt))))
3500 error ("%<else%> label does not match edge at end of bb %d\n",
3508 if (simple_goto_p (stmt))
3510 error ("Explicit goto at end of bb %d\n", bb->index);
3515 /* FIXME. We should double check that the labels in the
3516 destination blocks have their address taken. */
3517 FOR_EACH_EDGE (e, ei, bb->succs)
3518 if ((e->flags & (EDGE_FALLTHRU | EDGE_TRUE_VALUE
3519 | EDGE_FALSE_VALUE))
3520 || !(e->flags & EDGE_ABNORMAL))
3522 error ("Wrong outgoing edge flags at end of bb %d\n",
3530 if (EDGE_COUNT (bb->succs) != 1
3531 || (EDGE_SUCC (bb, 0)->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL
3532 | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
3534 error ("Wrong outgoing edge flags at end of bb %d\n", bb->index);
3537 if (EDGE_SUCC (bb, 0)->dest != EXIT_BLOCK_PTR)
3539 error ("Return edge does not point to exit in bb %d\n",
3552 vec = SWITCH_LABELS (stmt);
3553 n = TREE_VEC_LENGTH (vec);
3555 /* Mark all the destination basic blocks. */
3556 for (i = 0; i < n; ++i)
3558 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
3559 basic_block label_bb = label_to_block (lab);
3561 gcc_assert (!label_bb->aux || label_bb->aux == (void *)1);
3562 label_bb->aux = (void *)1;
3565 /* Verify that the case labels are sorted. */
3566 prev = TREE_VEC_ELT (vec, 0);
3567 for (i = 1; i < n - 1; ++i)
3569 tree c = TREE_VEC_ELT (vec, i);
3572 error ("Found default case not at end of case vector");
3576 if (! tree_int_cst_lt (CASE_LOW (prev), CASE_LOW (c)))
3578 error ("Case labels not sorted:\n ");
3579 print_generic_expr (stderr, prev, 0);
3580 fprintf (stderr," is greater than ");
3581 print_generic_expr (stderr, c, 0);
3582 fprintf (stderr," but comes before it.\n");
3587 if (CASE_LOW (TREE_VEC_ELT (vec, n - 1)))
3589 error ("No default case found at end of case vector");
3593 FOR_EACH_EDGE (e, ei, bb->succs)
3597 error ("Extra outgoing edge %d->%d\n",
3598 bb->index, e->dest->index);
3601 e->dest->aux = (void *)2;
3602 if ((e->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL
3603 | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
3605 error ("Wrong outgoing edge flags at end of bb %d\n",
3611 /* Check that we have all of them. */
3612 for (i = 0; i < n; ++i)
3614 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
3615 basic_block label_bb = label_to_block (lab);
3617 if (label_bb->aux != (void *)2)
3619 error ("Missing edge %i->%i\n",
3620 bb->index, label_bb->index);
3625 FOR_EACH_EDGE (e, ei, bb->succs)
3626 e->dest->aux = (void *)0;
3633 if (dom_computed[CDI_DOMINATORS] >= DOM_NO_FAST_QUERY)
3634 verify_dominators (CDI_DOMINATORS);
3640 /* Updates phi nodes after creating a forwarder block joined
3641 by edge FALLTHRU. */
3644 tree_make_forwarder_block (edge fallthru)
3648 basic_block dummy, bb;
3649 tree phi, new_phi, var, prev, next;
3651 dummy = fallthru->src;
3652 bb = fallthru->dest;
3654 if (EDGE_COUNT (bb->preds) == 1)
3657 /* If we redirected a branch we must create new phi nodes at the
3659 for (phi = phi_nodes (dummy); phi; phi = PHI_CHAIN (phi))
3661 var = PHI_RESULT (phi);
3662 new_phi = create_phi_node (var, bb);
3663 SSA_NAME_DEF_STMT (var) = new_phi;
3664 SET_PHI_RESULT (phi, make_ssa_name (SSA_NAME_VAR (var), phi));
3665 add_phi_arg (&new_phi, PHI_RESULT (phi), fallthru);
3668 /* Ensure that the PHI node chain is in the same order. */
3670 for (phi = phi_nodes (bb); phi; phi = next)
3672 next = PHI_CHAIN (phi);
3673 PHI_CHAIN (phi) = prev;
3676 set_phi_nodes (bb, prev);
3678 /* Add the arguments we have stored on edges. */
3679 FOR_EACH_EDGE (e, ei, bb->preds)
3684 for (phi = phi_nodes (bb), var = PENDING_STMT (e);
3686 phi = PHI_CHAIN (phi), var = TREE_CHAIN (var))
3687 add_phi_arg (&phi, TREE_VALUE (var), e);
3689 PENDING_STMT (e) = NULL;
3694 /* Return true if basic block BB does nothing except pass control
3695 flow to another block and that we can safely insert a label at
3696 the start of the successor block.
3698 As a precondition, we require that BB be not equal to
3702 tree_forwarder_block_p (basic_block bb)
3704 block_stmt_iterator bsi;
3708 /* If we have already determined that this block is not forwardable,
3709 then no further checks are necessary. */
3710 if (! bb_ann (bb)->forwardable)
3713 /* BB must have a single outgoing edge. */
3714 if (EDGE_COUNT (bb->succs) != 1
3715 /* BB can not have any PHI nodes. This could potentially be
3716 relaxed early in compilation if we re-rewrote the variables
3717 appearing in any PHI nodes in forwarder blocks. */
3719 /* BB may not be a predecessor of EXIT_BLOCK_PTR. */
3720 || EDGE_SUCC (bb, 0)->dest == EXIT_BLOCK_PTR
3721 /* BB may not have an abnormal outgoing edge. */
3722 || (EDGE_SUCC (bb, 0)->flags & EDGE_ABNORMAL))
3724 bb_ann (bb)->forwardable = 0;
3729 gcc_assert (bb != ENTRY_BLOCK_PTR);
3732 /* Successors of the entry block are not forwarders. */
3733 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
3736 bb_ann (bb)->forwardable = 0;
3740 /* Now walk through the statements. We can ignore labels, anything else
3741 means this is not a forwarder block. */
3742 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3744 tree stmt = bsi_stmt (bsi);
3746 switch (TREE_CODE (stmt))
3749 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)))
3754 bb_ann (bb)->forwardable = 0;
3763 /* Thread jumps over empty statements.
3765 This code should _not_ thread over obviously equivalent conditions
3766 as that requires nontrivial updates to the SSA graph.
3768 As a precondition, we require that all basic blocks be reachable.
3769 That is, there should be no opportunities left for
3770 delete_unreachable_blocks. */
3776 basic_block bb, dest, tmp, old_dest, curr, dom;
3779 bool retval = false;
3782 bb_ann (bb)->forwardable = 1;
3788 /* Don't waste time on forwarders. */
3789 if (tree_forwarder_block_p (bb))
3792 /* This block is now part of a forwarding path, mark it as not
3793 forwardable so that we can detect loops. This bit will be
3795 bb_ann (bb)->forwardable = 0;
3797 /* Examine each of our block's successors to see if it is
3799 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
3804 /* If the edge is abnormal or its destination is not
3805 forwardable, then there's nothing to do. */
3806 if ((e->flags & EDGE_ABNORMAL)
3807 || !tree_forwarder_block_p (e->dest))
3814 freq = EDGE_FREQUENCY (e);
3816 /* Now walk through as many forwarder blocks as possible to
3817 find the ultimate destination we want to thread our jump
3819 last = EDGE_SUCC (e->dest, 0);
3820 bb_ann (e->dest)->forwardable = 0;
3821 for (dest = EDGE_SUCC (e->dest, 0)->dest;
3822 tree_forwarder_block_p (dest);
3823 last = EDGE_SUCC (dest, 0),
3824 dest = EDGE_SUCC (dest, 0)->dest)
3825 bb_ann (dest)->forwardable = 0;
3827 /* Reset the forwardable marks to 1. */
3830 tmp = EDGE_SUCC (tmp, 0)->dest)
3831 bb_ann (tmp)->forwardable = 1;
3833 if (dest == e->dest)
3839 old = find_edge (bb, dest);
3842 /* If there already is an edge, check whether the values
3843 in phi nodes differ. */
3844 if (!phi_alternatives_equal (dest, last, old))
3846 /* The previous block is forwarder. Redirect our jump
3847 to that target instead since we know it has no PHI
3848 nodes that will need updating. */
3851 /* That might mean that no forwarding at all is possible. */
3852 if (dest == e->dest)
3858 old = find_edge (bb, dest);
3862 /* Perform the redirection. */
3865 e = redirect_edge_and_branch (e, dest);
3867 /* Update the profile. */
3868 if (profile_status != PROFILE_ABSENT)
3869 for (curr = old_dest; curr != dest; curr = EDGE_SUCC (curr, 0)->dest)
3871 curr->frequency -= freq;
3872 if (curr->frequency < 0)
3873 curr->frequency = 0;
3874 curr->count -= count;
3875 if (curr->count < 0)
3877 EDGE_SUCC (curr, 0)->count -= count;
3878 if (EDGE_SUCC (curr, 0)->count < 0)
3879 EDGE_SUCC (curr, 0)->count = 0;
3884 /* Update PHI nodes. We know that the new argument should
3885 have the same value as the argument associated with LAST.
3886 Otherwise we would have changed our target block above. */
3887 for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi))
3889 arg = phi_arg_from_edge (phi, last);
3890 gcc_assert (arg >= 0);
3891 add_phi_arg (&phi, PHI_ARG_DEF (phi, arg), e);
3895 /* Remove the unreachable blocks (observe that if all blocks
3896 were reachable before, only those in the path we threaded
3897 over and did not have any predecessor outside of the path
3898 become unreachable). */
3899 for (; old_dest != dest; old_dest = tmp)
3901 tmp = EDGE_SUCC (old_dest, 0)->dest;
3903 if (EDGE_COUNT (old_dest->preds) > 0)
3906 delete_basic_block (old_dest);
3909 /* Update the dominators. */
3910 if (dom_info_available_p (CDI_DOMINATORS))
3912 /* If the dominator of the destination was in the path, set its
3913 dominator to the start of the redirected edge. */
3914 if (get_immediate_dominator (CDI_DOMINATORS, old_dest) == NULL)
3915 set_immediate_dominator (CDI_DOMINATORS, old_dest, bb);
3917 /* Now proceed like if we forwarded just over one edge at a time.
3918 Algorithm for forwarding edge S --> A over edge A --> B then
3922 && !dominated_by (S, B))
3923 idom (B) = idom (A);
3924 recount_idom (A); */
3926 for (; old_dest != dest; old_dest = tmp)
3928 tmp = EDGE_SUCC (old_dest, 0)->dest;
3930 if (get_immediate_dominator (CDI_DOMINATORS, tmp) == old_dest
3931 && !dominated_by_p (CDI_DOMINATORS, bb, tmp))
3933 dom = get_immediate_dominator (CDI_DOMINATORS, old_dest);
3934 set_immediate_dominator (CDI_DOMINATORS, tmp, dom);
3937 dom = recount_dominator (CDI_DOMINATORS, old_dest);
3938 set_immediate_dominator (CDI_DOMINATORS, old_dest, dom);
3943 /* Reset the forwardable bit on our block since it's no longer in
3944 a forwarding chain path. */
3945 bb_ann (bb)->forwardable = 1;
3952 /* Return a non-special label in the head of basic block BLOCK.
3953 Create one if it doesn't exist. */
3956 tree_block_label (basic_block bb)
3958 block_stmt_iterator i, s = bsi_start (bb);
3962 for (i = s; !bsi_end_p (i); first = false, bsi_next (&i))
3964 stmt = bsi_stmt (i);
3965 if (TREE_CODE (stmt) != LABEL_EXPR)
3967 label = LABEL_EXPR_LABEL (stmt);
3968 if (!DECL_NONLOCAL (label))
3971 bsi_move_before (&i, &s);
3976 label = create_artificial_label ();
3977 stmt = build1 (LABEL_EXPR, void_type_node, label);
3978 bsi_insert_before (&s, stmt, BSI_NEW_STMT);
3983 /* Attempt to perform edge redirection by replacing a possibly complex
3984 jump instruction by a goto or by removing the jump completely.
3985 This can apply only if all edges now point to the same block. The
3986 parameters and return values are equivalent to
3987 redirect_edge_and_branch. */
3990 tree_try_redirect_by_replacing_jump (edge e, basic_block target)
3992 basic_block src = e->src;
3994 block_stmt_iterator b;
3998 /* Verify that all targets will be TARGET. */
3999 FOR_EACH_EDGE (tmp, ei, src->succs)
4000 if (tmp->dest != target && tmp != e)
4009 stmt = bsi_stmt (b);
4011 if (TREE_CODE (stmt) == COND_EXPR
4012 || TREE_CODE (stmt) == SWITCH_EXPR)
4015 e = ssa_redirect_edge (e, target);
4016 e->flags = EDGE_FALLTHRU;
4024 /* Redirect E to DEST. Return NULL on failure. Otherwise, return the
4025 edge representing the redirected branch. */
4028 tree_redirect_edge_and_branch (edge e, basic_block dest)
4030 basic_block bb = e->src;
4031 block_stmt_iterator bsi;
4035 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
4038 if (e->src != ENTRY_BLOCK_PTR
4039 && (ret = tree_try_redirect_by_replacing_jump (e, dest)))
4042 if (e->dest == dest)
4045 label = tree_block_label (dest);
4047 bsi = bsi_last (bb);
4048 stmt = bsi_end_p (bsi) ? NULL : bsi_stmt (bsi);
4050 switch (stmt ? TREE_CODE (stmt) : ERROR_MARK)
4053 stmt = (e->flags & EDGE_TRUE_VALUE
4054 ? COND_EXPR_THEN (stmt)
4055 : COND_EXPR_ELSE (stmt));
4056 GOTO_DESTINATION (stmt) = label;
4060 /* No non-abnormal edges should lead from a non-simple goto, and
4061 simple ones should be represented implicitly. */
4066 tree vec = SWITCH_LABELS (stmt);
4067 size_t i, n = TREE_VEC_LENGTH (vec);
4069 for (i = 0; i < n; ++i)
4071 tree elt = TREE_VEC_ELT (vec, i);
4072 if (label_to_block (CASE_LABEL (elt)) == e->dest)
4073 CASE_LABEL (elt) = label;
4080 e->flags |= EDGE_FALLTHRU;
4084 /* Otherwise it must be a fallthru edge, and we don't need to
4085 do anything besides redirecting it. */
4086 gcc_assert (e->flags & EDGE_FALLTHRU);
4090 /* Update/insert PHI nodes as necessary. */
4092 /* Now update the edges in the CFG. */
4093 e = ssa_redirect_edge (e, dest);
4099 /* Simple wrapper, as we can always redirect fallthru edges. */
4102 tree_redirect_edge_and_branch_force (edge e, basic_block dest)
4104 e = tree_redirect_edge_and_branch (e, dest);
4111 /* Splits basic block BB after statement STMT (but at least after the
4112 labels). If STMT is NULL, BB is split just after the labels. */
4115 tree_split_block (basic_block bb, void *stmt)
4117 block_stmt_iterator bsi, bsi_tgt;
4123 new_bb = create_empty_bb (bb);
4125 /* Redirect the outgoing edges. */
4126 new_bb->succs = bb->succs;
4128 FOR_EACH_EDGE (e, ei, new_bb->succs)
4131 if (stmt && TREE_CODE ((tree) stmt) == LABEL_EXPR)
4134 /* Move everything from BSI to the new basic block. */
4135 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4137 act = bsi_stmt (bsi);
4138 if (TREE_CODE (act) == LABEL_EXPR)
4151 bsi_tgt = bsi_start (new_bb);
4152 while (!bsi_end_p (bsi))
4154 act = bsi_stmt (bsi);
4156 bsi_insert_after (&bsi_tgt, act, BSI_NEW_STMT);
4163 /* Moves basic block BB after block AFTER. */
4166 tree_move_block_after (basic_block bb, basic_block after)
4168 if (bb->prev_bb == after)
4172 link_block (bb, after);
4178 /* Return true if basic_block can be duplicated. */
4181 tree_can_duplicate_bb_p (basic_block bb ATTRIBUTE_UNUSED)
4186 /* Create a duplicate of the basic block BB. NOTE: This does not
4187 preserve SSA form. */
4190 tree_duplicate_bb (basic_block bb)
4193 block_stmt_iterator bsi, bsi_tgt;
4195 ssa_op_iter op_iter;
4197 new_bb = create_empty_bb (EXIT_BLOCK_PTR->prev_bb);
4199 /* First copy the phi nodes. We do not copy phi node arguments here,
4200 since the edges are not ready yet. Keep the chain of phi nodes in
4201 the same order, so that we can add them later. */
4202 for (phi = phi_nodes (bb); phi; phi = TREE_CHAIN (phi))
4204 mark_for_rewrite (PHI_RESULT (phi));
4205 create_phi_node (PHI_RESULT (phi), new_bb);
4207 set_phi_nodes (new_bb, nreverse (phi_nodes (new_bb)));
4209 bsi_tgt = bsi_start (new_bb);
4210 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4212 tree stmt = bsi_stmt (bsi);
4215 if (TREE_CODE (stmt) == LABEL_EXPR)
4218 /* Record the definitions. */
4219 get_stmt_operands (stmt);
4221 FOR_EACH_SSA_TREE_OPERAND (val, stmt, op_iter, SSA_OP_ALL_DEFS)
4222 mark_for_rewrite (val);
4224 copy = unshare_expr (stmt);
4226 /* Copy also the virtual operands. */
4227 get_stmt_ann (copy);
4228 copy_virtual_operands (copy, stmt);
4230 bsi_insert_after (&bsi_tgt, copy, BSI_NEW_STMT);
4236 /* Basic block BB_COPY was created by code duplication. Add phi node
4237 arguments for edges going out of BB_COPY. The blocks that were
4238 duplicated have rbi->duplicated set to one. */
4241 add_phi_args_after_copy_bb (basic_block bb_copy)
4243 basic_block bb, dest;
4246 tree phi, phi_copy, phi_next, def;
4248 bb = bb_copy->rbi->original;
4250 FOR_EACH_EDGE (e_copy, ei, bb_copy->succs)
4252 if (!phi_nodes (e_copy->dest))
4255 if (e_copy->dest->rbi->duplicated)
4256 dest = e_copy->dest->rbi->original;
4258 dest = e_copy->dest;
4260 e = find_edge (bb, dest);
4263 /* During loop unrolling the target of the latch edge is copied.
4264 In this case we are not looking for edge to dest, but to
4265 duplicated block whose original was dest. */
4266 FOR_EACH_EDGE (e, ei, bb->succs)
4267 if (e->dest->rbi->duplicated
4268 && e->dest->rbi->original == dest)
4271 gcc_assert (e != NULL);
4274 for (phi = phi_nodes (e->dest), phi_copy = phi_nodes (e_copy->dest);
4276 phi = phi_next, phi_copy = TREE_CHAIN (phi_copy))
4278 phi_next = TREE_CHAIN (phi);
4280 gcc_assert (PHI_RESULT (phi) == PHI_RESULT (phi_copy));
4281 def = PHI_ARG_DEF_FROM_EDGE (phi, e);
4282 add_phi_arg (&phi_copy, def, e_copy);
4287 /* Blocks in REGION_COPY array of length N_REGION were created by
4288 duplication of basic blocks. Add phi node arguments for edges
4289 going from these blocks. */
4292 add_phi_args_after_copy (basic_block *region_copy, unsigned n_region)
4296 for (i = 0; i < n_region; i++)
4297 region_copy[i]->rbi->duplicated = 1;
4299 for (i = 0; i < n_region; i++)
4300 add_phi_args_after_copy_bb (region_copy[i]);
4302 for (i = 0; i < n_region; i++)
4303 region_copy[i]->rbi->duplicated = 0;
4306 /* Maps the old ssa name FROM_NAME to TO_NAME. */
4308 struct ssa_name_map_entry
4314 /* Hash function for ssa_name_map_entry. */
4317 ssa_name_map_entry_hash (const void *entry)
4319 const struct ssa_name_map_entry *en = entry;
4320 return SSA_NAME_VERSION (en->from_name);
4323 /* Equality function for ssa_name_map_entry. */
4326 ssa_name_map_entry_eq (const void *in_table, const void *ssa_name)
4328 const struct ssa_name_map_entry *en = in_table;
4330 return en->from_name == ssa_name;
4333 /* Allocate duplicates of ssa names in list DEFINITIONS and store the mapping
4337 allocate_ssa_names (bitmap definitions, htab_t *map)
4340 struct ssa_name_map_entry *entry;
4346 *map = htab_create (10, ssa_name_map_entry_hash,
4347 ssa_name_map_entry_eq, free);
4348 EXECUTE_IF_SET_IN_BITMAP (definitions, 0, ver, bi)
4350 name = ssa_name (ver);
4351 slot = htab_find_slot_with_hash (*map, name, SSA_NAME_VERSION (name),
4357 entry = xmalloc (sizeof (struct ssa_name_map_entry));
4358 entry->from_name = name;
4361 entry->to_name = duplicate_ssa_name (name, SSA_NAME_DEF_STMT (name));
4365 /* Rewrite the definition DEF in statement STMT to new ssa name as specified
4366 by the mapping MAP. */
4369 rewrite_to_new_ssa_names_def (def_operand_p def, tree stmt, htab_t map)
4371 tree name = DEF_FROM_PTR (def);
4372 struct ssa_name_map_entry *entry;
4374 gcc_assert (TREE_CODE (name) == SSA_NAME);
4376 entry = htab_find_with_hash (map, name, SSA_NAME_VERSION (name));
4380 SET_DEF (def, entry->to_name);
4381 SSA_NAME_DEF_STMT (entry->to_name) = stmt;
4384 /* Rewrite the USE to new ssa name as specified by the mapping MAP. */
4387 rewrite_to_new_ssa_names_use (use_operand_p use, htab_t map)
4389 tree name = USE_FROM_PTR (use);
4390 struct ssa_name_map_entry *entry;
4392 if (TREE_CODE (name) != SSA_NAME)
4395 entry = htab_find_with_hash (map, name, SSA_NAME_VERSION (name));
4399 SET_USE (use, entry->to_name);
4402 /* Rewrite the ssa names in basic block BB to new ones as specified by the
4406 rewrite_to_new_ssa_names_bb (basic_block bb, htab_t map)
4412 block_stmt_iterator bsi;
4416 v_may_def_optype v_may_defs;
4417 v_must_def_optype v_must_defs;
4420 FOR_EACH_EDGE (e, ei, bb->preds)
4421 if (e->flags & EDGE_ABNORMAL)
4424 for (phi = phi_nodes (bb); phi; phi = TREE_CHAIN (phi))
4426 rewrite_to_new_ssa_names_def (PHI_RESULT_PTR (phi), phi, map);
4428 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (PHI_RESULT (phi)) = 1;
4431 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4433 stmt = bsi_stmt (bsi);
4434 get_stmt_operands (stmt);
4435 ann = stmt_ann (stmt);
4437 uses = USE_OPS (ann);
4438 for (i = 0; i < NUM_USES (uses); i++)
4439 rewrite_to_new_ssa_names_use (USE_OP_PTR (uses, i), map);
4441 defs = DEF_OPS (ann);
4442 for (i = 0; i < NUM_DEFS (defs); i++)
4443 rewrite_to_new_ssa_names_def (DEF_OP_PTR (defs, i), stmt, map);
4445 vuses = VUSE_OPS (ann);
4446 for (i = 0; i < NUM_VUSES (vuses); i++)
4447 rewrite_to_new_ssa_names_use (VUSE_OP_PTR (vuses, i), map);
4449 v_may_defs = V_MAY_DEF_OPS (ann);
4450 for (i = 0; i < NUM_V_MAY_DEFS (v_may_defs); i++)
4452 rewrite_to_new_ssa_names_use
4453 (V_MAY_DEF_OP_PTR (v_may_defs, i), map);
4454 rewrite_to_new_ssa_names_def
4455 (V_MAY_DEF_RESULT_PTR (v_may_defs, i), stmt, map);
4458 v_must_defs = V_MUST_DEF_OPS (ann);
4459 for (i = 0; i < NUM_V_MUST_DEFS (v_must_defs); i++)
4460 rewrite_to_new_ssa_names_def
4461 (V_MUST_DEF_OP_PTR (v_must_defs, i), stmt, map);
4464 FOR_EACH_EDGE (e, ei, bb->succs)
4465 for (phi = phi_nodes (e->dest); phi; phi = TREE_CHAIN (phi))
4467 rewrite_to_new_ssa_names_use
4468 (PHI_ARG_DEF_PTR_FROM_EDGE (phi, e), map);
4470 if (e->flags & EDGE_ABNORMAL)
4472 tree op = PHI_ARG_DEF_FROM_EDGE (phi, e);
4473 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op) = 1;
4478 /* Rewrite the ssa names in N_REGION blocks REGION to the new ones as specified
4479 by the mapping MAP. */
4482 rewrite_to_new_ssa_names (basic_block *region, unsigned n_region, htab_t map)
4486 for (r = 0; r < n_region; r++)
4487 rewrite_to_new_ssa_names_bb (region[r], map);
4490 /* Duplicates a REGION (set of N_REGION basic blocks) with just a single
4491 important exit edge EXIT. By important we mean that no SSA name defined
4492 inside region is live over the other exit edges of the region. All entry
4493 edges to the region must go to ENTRY->dest. The edge ENTRY is redirected
4494 to the duplicate of the region. SSA form, dominance and loop information
4495 is updated. The new basic blocks are stored to REGION_COPY in the same
4496 order as they had in REGION, provided that REGION_COPY is not NULL.
4497 The function returns false if it is unable to copy the region,
4501 tree_duplicate_sese_region (edge entry, edge exit,
4502 basic_block *region, unsigned n_region,
4503 basic_block *region_copy)
4505 unsigned i, n_doms, ver;
4506 bool free_region_copy = false, copying_header = false;
4507 struct loop *loop = entry->dest->loop_father;
4512 htab_t ssa_name_map = NULL;
4516 if (!can_copy_bbs_p (region, n_region))
4519 /* Some sanity checking. Note that we do not check for all possible
4520 missuses of the functions. I.e. if you ask to copy something weird,
4521 it will work, but the state of structures probably will not be
4524 for (i = 0; i < n_region; i++)
4526 /* We do not handle subloops, i.e. all the blocks must belong to the
4528 if (region[i]->loop_father != loop)
4531 if (region[i] != entry->dest
4532 && region[i] == loop->header)
4538 /* In case the function is used for loop header copying (which is the primary
4539 use), ensure that EXIT and its copy will be new latch and entry edges. */
4540 if (loop->header == entry->dest)
4542 copying_header = true;
4543 loop->copy = loop->outer;
4545 if (!dominated_by_p (CDI_DOMINATORS, loop->latch, exit->src))
4548 for (i = 0; i < n_region; i++)
4549 if (region[i] != exit->src
4550 && dominated_by_p (CDI_DOMINATORS, region[i], exit->src))
4556 region_copy = xmalloc (sizeof (basic_block) * n_region);
4557 free_region_copy = true;
4560 gcc_assert (!any_marked_for_rewrite_p ());
4562 /* Record blocks outside the region that are duplicated by something
4564 doms = xmalloc (sizeof (basic_block) * n_basic_blocks);
4565 n_doms = get_dominated_by_region (CDI_DOMINATORS, region, n_region, doms);
4567 copy_bbs (region, n_region, region_copy, &exit, 1, &exit_copy, loop);
4568 definitions = marked_ssa_names ();
4572 loop->header = exit->dest;
4573 loop->latch = exit->src;
4576 /* Redirect the entry and add the phi node arguments. */
4577 redirected = redirect_edge_and_branch (entry, entry->dest->rbi->copy);
4578 gcc_assert (redirected != NULL);
4579 for (phi = phi_nodes (entry->dest), var = PENDING_STMT (entry);
4581 phi = TREE_CHAIN (phi), var = TREE_CHAIN (var))
4582 add_phi_arg (&phi, TREE_VALUE (var), entry);
4583 PENDING_STMT (entry) = NULL;
4585 /* Concerning updating of dominators: We must recount dominators
4586 for entry block and its copy. Anything that is outside of the region, but
4587 was dominated by something inside needs recounting as well. */
4588 set_immediate_dominator (CDI_DOMINATORS, entry->dest, entry->src);
4589 doms[n_doms++] = entry->dest->rbi->original;
4590 iterate_fix_dominators (CDI_DOMINATORS, doms, n_doms);
4593 /* Add the other phi node arguments. */
4594 add_phi_args_after_copy (region_copy, n_region);
4596 /* Add phi nodes for definitions at exit. TODO -- once we have immediate
4597 uses, it should be possible to emit phi nodes just for definitions that
4598 are used outside region. */
4599 EXECUTE_IF_SET_IN_BITMAP (definitions, 0, ver, bi)
4601 tree name = ssa_name (ver);
4603 phi = create_phi_node (name, exit->dest);
4604 add_phi_arg (&phi, name, exit);
4605 add_phi_arg (&phi, name, exit_copy);
4607 SSA_NAME_DEF_STMT (name) = phi;
4610 /* And create new definitions inside region and its copy. TODO -- once we
4611 have immediate uses, it might be better to leave definitions in region
4612 unchanged, create new ssa names for phi nodes on exit, and rewrite
4613 the uses, to avoid changing the copied region. */
4614 allocate_ssa_names (definitions, &ssa_name_map);
4615 rewrite_to_new_ssa_names (region, n_region, ssa_name_map);
4616 allocate_ssa_names (definitions, &ssa_name_map);
4617 rewrite_to_new_ssa_names (region_copy, n_region, ssa_name_map);
4618 htab_delete (ssa_name_map);
4620 if (free_region_copy)
4623 unmark_all_for_rewrite ();
4624 BITMAP_XFREE (definitions);
4629 /* Dump FUNCTION_DECL FN to file FILE using FLAGS (see TDF_* in tree.h) */
4632 dump_function_to_file (tree fn, FILE *file, int flags)
4634 tree arg, vars, var;
4635 bool ignore_topmost_bind = false, any_var = false;
4639 fprintf (file, "%s (", lang_hooks.decl_printable_name (fn, 2));
4641 arg = DECL_ARGUMENTS (fn);
4644 print_generic_expr (file, arg, dump_flags);
4645 if (TREE_CHAIN (arg))
4646 fprintf (file, ", ");
4647 arg = TREE_CHAIN (arg);
4649 fprintf (file, ")\n");
4651 if (flags & TDF_RAW)
4653 dump_node (fn, TDF_SLIM | flags, file);
4657 /* When GIMPLE is lowered, the variables are no longer available in
4658 BIND_EXPRs, so display them separately. */
4659 if (cfun && cfun->unexpanded_var_list)
4661 ignore_topmost_bind = true;
4663 fprintf (file, "{\n");
4664 for (vars = cfun->unexpanded_var_list; vars; vars = TREE_CHAIN (vars))
4666 var = TREE_VALUE (vars);
4668 print_generic_decl (file, var, flags);
4669 fprintf (file, "\n");
4675 if (basic_block_info)
4677 /* Make a CFG based dump. */
4678 check_bb_profile (ENTRY_BLOCK_PTR, file);
4679 if (!ignore_topmost_bind)
4680 fprintf (file, "{\n");
4682 if (any_var && n_basic_blocks)
4683 fprintf (file, "\n");
4686 dump_generic_bb (file, bb, 2, flags);
4688 fprintf (file, "}\n");
4689 check_bb_profile (EXIT_BLOCK_PTR, file);
4695 /* Make a tree based dump. */
4696 chain = DECL_SAVED_TREE (fn);
4698 if (TREE_CODE (chain) == BIND_EXPR)
4700 if (ignore_topmost_bind)
4702 chain = BIND_EXPR_BODY (chain);
4710 if (!ignore_topmost_bind)
4711 fprintf (file, "{\n");
4716 fprintf (file, "\n");
4718 print_generic_stmt_indented (file, chain, flags, indent);
4719 if (ignore_topmost_bind)
4720 fprintf (file, "}\n");
4723 fprintf (file, "\n\n");
4727 /* Pretty print of the loops intermediate representation. */
4728 static void print_loop (FILE *, struct loop *, int);
4729 static void print_pred_bbs (FILE *, basic_block bb);
4730 static void print_succ_bbs (FILE *, basic_block bb);
4733 /* Print the predecessors indexes of edge E on FILE. */
4736 print_pred_bbs (FILE *file, basic_block bb)
4741 FOR_EACH_EDGE (e, ei, bb->preds)
4742 fprintf (file, "bb_%d", e->src->index);
4746 /* Print the successors indexes of edge E on FILE. */
4749 print_succ_bbs (FILE *file, basic_block bb)
4754 FOR_EACH_EDGE (e, ei, bb->succs)
4755 fprintf (file, "bb_%d", e->src->index);
4759 /* Pretty print LOOP on FILE, indented INDENT spaces. */
4762 print_loop (FILE *file, struct loop *loop, int indent)
4770 s_indent = (char *) alloca ((size_t) indent + 1);
4771 memset ((void *) s_indent, ' ', (size_t) indent);
4772 s_indent[indent] = '\0';
4774 /* Print the loop's header. */
4775 fprintf (file, "%sloop_%d\n", s_indent, loop->num);
4777 /* Print the loop's body. */
4778 fprintf (file, "%s{\n", s_indent);
4780 if (bb->loop_father == loop)
4782 /* Print the basic_block's header. */
4783 fprintf (file, "%s bb_%d (preds = {", s_indent, bb->index);
4784 print_pred_bbs (file, bb);
4785 fprintf (file, "}, succs = {");
4786 print_succ_bbs (file, bb);
4787 fprintf (file, "})\n");
4789 /* Print the basic_block's body. */
4790 fprintf (file, "%s {\n", s_indent);
4791 tree_dump_bb (bb, file, indent + 4);
4792 fprintf (file, "%s }\n", s_indent);
4795 print_loop (file, loop->inner, indent + 2);
4796 fprintf (file, "%s}\n", s_indent);
4797 print_loop (file, loop->next, indent);
4801 /* Follow a CFG edge from the entry point of the program, and on entry
4802 of a loop, pretty print the loop structure on FILE. */
4805 print_loop_ir (FILE *file)
4809 bb = BASIC_BLOCK (0);
4810 if (bb && bb->loop_father)
4811 print_loop (file, bb->loop_father, 0);
4815 /* Debugging loops structure at tree level. */
4818 debug_loop_ir (void)
4820 print_loop_ir (stderr);
4824 /* Return true if BB ends with a call, possibly followed by some
4825 instructions that must stay with the call. Return false,
4829 tree_block_ends_with_call_p (basic_block bb)
4831 block_stmt_iterator bsi = bsi_last (bb);
4832 return get_call_expr_in (bsi_stmt (bsi)) != NULL;
4836 /* Return true if BB ends with a conditional branch. Return false,
4840 tree_block_ends_with_condjump_p (basic_block bb)
4842 tree stmt = tsi_stmt (bsi_last (bb).tsi);
4843 return (TREE_CODE (stmt) == COND_EXPR);
4847 /* Return true if we need to add fake edge to exit at statement T.
4848 Helper function for tree_flow_call_edges_add. */
4851 need_fake_edge_p (tree t)
4855 /* NORETURN and LONGJMP calls already have an edge to exit.
4856 CONST, PURE and ALWAYS_RETURN calls do not need one.
4857 We don't currently check for CONST and PURE here, although
4858 it would be a good idea, because those attributes are
4859 figured out from the RTL in mark_constant_function, and
4860 the counter incrementation code from -fprofile-arcs
4861 leads to different results from -fbranch-probabilities. */
4862 call = get_call_expr_in (t);
4864 && !(call_expr_flags (call) &
4865 (ECF_NORETURN | ECF_LONGJMP | ECF_ALWAYS_RETURN)))
4868 if (TREE_CODE (t) == ASM_EXPR
4869 && (ASM_VOLATILE_P (t) || ASM_INPUT_P (t)))
4876 /* Add fake edges to the function exit for any non constant and non
4877 noreturn calls, volatile inline assembly in the bitmap of blocks
4878 specified by BLOCKS or to the whole CFG if BLOCKS is zero. Return
4879 the number of blocks that were split.
4881 The goal is to expose cases in which entering a basic block does
4882 not imply that all subsequent instructions must be executed. */
4885 tree_flow_call_edges_add (sbitmap blocks)
4888 int blocks_split = 0;
4889 int last_bb = last_basic_block;
4890 bool check_last_block = false;
4892 if (n_basic_blocks == 0)
4896 check_last_block = true;
4898 check_last_block = TEST_BIT (blocks, EXIT_BLOCK_PTR->prev_bb->index);
4900 /* In the last basic block, before epilogue generation, there will be
4901 a fallthru edge to EXIT. Special care is required if the last insn
4902 of the last basic block is a call because make_edge folds duplicate
4903 edges, which would result in the fallthru edge also being marked
4904 fake, which would result in the fallthru edge being removed by
4905 remove_fake_edges, which would result in an invalid CFG.
4907 Moreover, we can't elide the outgoing fake edge, since the block
4908 profiler needs to take this into account in order to solve the minimal
4909 spanning tree in the case that the call doesn't return.
4911 Handle this by adding a dummy instruction in a new last basic block. */
4912 if (check_last_block)
4915 basic_block bb = EXIT_BLOCK_PTR->prev_bb;
4916 block_stmt_iterator bsi = bsi_last (bb);
4918 if (!bsi_end_p (bsi))
4921 if (need_fake_edge_p (t))
4925 FOR_EACH_EDGE (e, ei, bb->succs)
4926 if (e->dest == EXIT_BLOCK_PTR)
4928 bsi_insert_on_edge (e, build_empty_stmt ());
4929 bsi_commit_edge_inserts ((int *)NULL);
4935 /* Now add fake edges to the function exit for any non constant
4936 calls since there is no way that we can determine if they will
4938 for (i = 0; i < last_bb; i++)
4940 basic_block bb = BASIC_BLOCK (i);
4941 block_stmt_iterator bsi;
4942 tree stmt, last_stmt;
4947 if (blocks && !TEST_BIT (blocks, i))
4950 bsi = bsi_last (bb);
4951 if (!bsi_end_p (bsi))
4953 last_stmt = bsi_stmt (bsi);
4956 stmt = bsi_stmt (bsi);
4957 if (need_fake_edge_p (stmt))
4960 /* The handling above of the final block before the
4961 epilogue should be enough to verify that there is
4962 no edge to the exit block in CFG already.
4963 Calling make_edge in such case would cause us to
4964 mark that edge as fake and remove it later. */
4965 #ifdef ENABLE_CHECKING
4966 if (stmt == last_stmt)
4969 FOR_EACH_EDGE (e, ei, bb->succs)
4970 gcc_assert (e->dest != EXIT_BLOCK_PTR);
4974 /* Note that the following may create a new basic block
4975 and renumber the existing basic blocks. */
4976 if (stmt != last_stmt)
4978 e = split_block (bb, stmt);
4982 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
4986 while (!bsi_end_p (bsi));
4991 verify_flow_info ();
4993 return blocks_split;
4997 tree_purge_dead_eh_edges (basic_block bb)
4999 bool changed = false;
5002 tree stmt = last_stmt (bb);
5004 if (stmt && tree_can_throw_internal (stmt))
5007 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
5009 if (e->flags & EDGE_EH)
5011 ssa_remove_edge (e);
5018 /* Removal of dead EH edges might change dominators of not
5019 just immediate successors. E.g. when bb1 is changed so that
5020 it no longer can throw and bb1->bb3 and bb1->bb4 are dead
5021 eh edges purged by this function in:
5033 idom(bb5) must be recomputed. For now just free the dominance
5036 free_dominance_info (CDI_DOMINATORS);
5042 tree_purge_all_dead_eh_edges (bitmap blocks)
5044 bool changed = false;
5048 EXECUTE_IF_SET_IN_BITMAP (blocks, 0, i, bi)
5050 changed |= tree_purge_dead_eh_edges (BASIC_BLOCK (i));
5056 struct cfg_hooks tree_cfg_hooks = {
5058 tree_verify_flow_info,
5059 tree_dump_bb, /* dump_bb */
5060 create_bb, /* create_basic_block */
5061 tree_redirect_edge_and_branch,/* redirect_edge_and_branch */
5062 tree_redirect_edge_and_branch_force,/* redirect_edge_and_branch_force */
5063 remove_bb, /* delete_basic_block */
5064 tree_split_block, /* split_block */
5065 tree_move_block_after, /* move_block_after */
5066 tree_can_merge_blocks_p, /* can_merge_blocks_p */
5067 tree_merge_blocks, /* merge_blocks */
5068 tree_predict_edge, /* predict_edge */
5069 tree_predicted_by_p, /* predicted_by_p */
5070 tree_can_duplicate_bb_p, /* can_duplicate_block_p */
5071 tree_duplicate_bb, /* duplicate_block */
5072 tree_split_edge, /* split_edge */
5073 tree_make_forwarder_block, /* make_forward_block */
5074 NULL, /* tidy_fallthru_edge */
5075 tree_block_ends_with_call_p, /* block_ends_with_call_p */
5076 tree_block_ends_with_condjump_p, /* block_ends_with_condjump_p */
5077 tree_flow_call_edges_add /* flow_call_edges_add */
5081 /* Split all critical edges. */
5084 split_critical_edges (void)
5092 FOR_EACH_EDGE (e, ei, bb->succs)
5093 if (EDGE_CRITICAL_P (e) && !(e->flags & EDGE_ABNORMAL))
5100 struct tree_opt_pass pass_split_crit_edges =
5102 "crited", /* name */
5104 split_critical_edges, /* execute */
5107 0, /* static_pass_number */
5108 TV_TREE_SPLIT_EDGES, /* tv_id */
5109 PROP_cfg, /* properties required */
5110 PROP_no_crit_edges, /* properties_provided */
5111 0, /* properties_destroyed */
5112 0, /* todo_flags_start */
5113 TODO_dump_func, /* todo_flags_finish */
5118 /* Return EXP if it is a valid GIMPLE rvalue, else gimplify it into
5119 a temporary, make sure and register it to be renamed if necessary,
5120 and finally return the temporary. Put the statements to compute
5121 EXP before the current statement in BSI. */
5124 gimplify_val (block_stmt_iterator *bsi, tree type, tree exp)
5126 tree t, new_stmt, orig_stmt;
5128 if (is_gimple_val (exp))
5131 t = make_rename_temp (type, NULL);
5132 new_stmt = build (MODIFY_EXPR, type, t, exp);
5134 orig_stmt = bsi_stmt (*bsi);
5135 SET_EXPR_LOCUS (new_stmt, EXPR_LOCUS (orig_stmt));
5136 TREE_BLOCK (new_stmt) = TREE_BLOCK (orig_stmt);
5138 bsi_insert_before (bsi, new_stmt, BSI_SAME_STMT);
5143 /* Build a ternary operation and gimplify it. Emit code before BSI.
5144 Return the gimple_val holding the result. */
5147 gimplify_build3 (block_stmt_iterator *bsi, enum tree_code code,
5148 tree type, tree a, tree b, tree c)
5152 ret = fold (build3 (code, type, a, b, c));
5155 return gimplify_val (bsi, type, ret);
5158 /* Build a binary operation and gimplify it. Emit code before BSI.
5159 Return the gimple_val holding the result. */
5162 gimplify_build2 (block_stmt_iterator *bsi, enum tree_code code,
5163 tree type, tree a, tree b)
5167 ret = fold (build2 (code, type, a, b));
5170 return gimplify_val (bsi, type, ret);
5173 /* Build a unary operation and gimplify it. Emit code before BSI.
5174 Return the gimple_val holding the result. */
5177 gimplify_build1 (block_stmt_iterator *bsi, enum tree_code code, tree type,
5182 ret = fold (build1 (code, type, a));
5185 return gimplify_val (bsi, type, ret);
5190 /* Emit return warnings. */
5193 execute_warn_function_return (void)
5195 #ifdef USE_MAPPED_LOCATION
5196 source_location location;
5204 if (warn_missing_noreturn
5205 && !TREE_THIS_VOLATILE (cfun->decl)
5206 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) == 0
5207 && !lang_hooks.function.missing_noreturn_ok_p (cfun->decl))
5208 warning ("%Jfunction might be possible candidate for "
5209 "attribute %<noreturn%>",
5212 /* If we have a path to EXIT, then we do return. */
5213 if (TREE_THIS_VOLATILE (cfun->decl)
5214 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) > 0)
5216 #ifdef USE_MAPPED_LOCATION
5217 location = UNKNOWN_LOCATION;
5221 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
5223 last = last_stmt (e->src);
5224 if (TREE_CODE (last) == RETURN_EXPR
5225 #ifdef USE_MAPPED_LOCATION
5226 && (location = EXPR_LOCATION (last)) != UNKNOWN_LOCATION)
5228 && (locus = EXPR_LOCUS (last)) != NULL)
5232 #ifdef USE_MAPPED_LOCATION
5233 if (location == UNKNOWN_LOCATION)
5234 location = cfun->function_end_locus;
5235 warning ("%H%<noreturn%> function does return", &location);
5238 locus = &cfun->function_end_locus;
5239 warning ("%H%<noreturn%> function does return", locus);
5243 /* If we see "return;" in some basic block, then we do reach the end
5244 without returning a value. */
5245 else if (warn_return_type
5246 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) > 0
5247 && !VOID_TYPE_P (TREE_TYPE (TREE_TYPE (cfun->decl))))
5249 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
5251 tree last = last_stmt (e->src);
5252 if (TREE_CODE (last) == RETURN_EXPR
5253 && TREE_OPERAND (last, 0) == NULL)
5255 #ifdef USE_MAPPED_LOCATION
5256 location = EXPR_LOCATION (last);
5257 if (location == UNKNOWN_LOCATION)
5258 location = cfun->function_end_locus;
5259 warning ("%Hcontrol reaches end of non-void function", &location);
5261 locus = EXPR_LOCUS (last);
5263 locus = &cfun->function_end_locus;
5264 warning ("%Hcontrol reaches end of non-void function", locus);
5273 /* Given a basic block B which ends with a conditional and has
5274 precisely two successors, determine which of the edges is taken if
5275 the conditional is true and which is taken if the conditional is
5276 false. Set TRUE_EDGE and FALSE_EDGE appropriately. */
5279 extract_true_false_edges_from_block (basic_block b,
5283 edge e = EDGE_SUCC (b, 0);
5285 if (e->flags & EDGE_TRUE_VALUE)
5288 *false_edge = EDGE_SUCC (b, 1);
5293 *true_edge = EDGE_SUCC (b, 1);
5297 struct tree_opt_pass pass_warn_function_return =
5301 execute_warn_function_return, /* execute */
5304 0, /* static_pass_number */
5306 PROP_cfg, /* properties_required */
5307 0, /* properties_provided */
5308 0, /* properties_destroyed */
5309 0, /* todo_flags_start */
5310 0, /* todo_flags_finish */
5314 #include "gt-tree-cfg.h"