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);)
1815 tree stmt = bsi_stmt (i);
1816 if (TREE_CODE (stmt) == LABEL_EXPR
1817 && FORCED_LABEL (LABEL_EXPR_LABEL (stmt)))
1819 basic_block new_bb = bb->prev_bb;
1820 block_stmt_iterator new_bsi = bsi_after_labels (new_bb);
1823 bsi_insert_after (&new_bsi, stmt, BSI_NEW_STMT);
1827 release_defs (stmt);
1829 set_bb_for_stmt (stmt, NULL);
1833 /* Don't warn for removed gotos. Gotos are often removed due to
1834 jump threading, thus resulting in bogus warnings. Not great,
1835 since this way we lose warnings for gotos in the original
1836 program that are indeed unreachable. */
1837 if (TREE_CODE (stmt) != GOTO_EXPR && EXPR_HAS_LOCATION (stmt) && !loc)
1838 #ifdef USE_MAPPED_LOCATION
1839 loc = EXPR_LOCATION (stmt);
1841 loc = EXPR_LOCUS (stmt);
1845 /* If requested, give a warning that the first statement in the
1846 block is unreachable. We walk statements backwards in the
1847 loop above, so the last statement we process is the first statement
1849 if (warn_notreached && loc)
1850 #ifdef USE_MAPPED_LOCATION
1851 warning ("%Hwill never be executed", &loc);
1853 warning ("%Hwill never be executed", loc);
1856 remove_phi_nodes_and_edges_for_unreachable_block (bb);
1859 /* Try to remove superfluous control structures. */
1862 cleanup_control_flow (void)
1865 block_stmt_iterator bsi;
1866 bool retval = false;
1871 bsi = bsi_last (bb);
1873 if (bsi_end_p (bsi))
1876 stmt = bsi_stmt (bsi);
1877 if (TREE_CODE (stmt) == COND_EXPR
1878 || TREE_CODE (stmt) == SWITCH_EXPR)
1879 retval |= cleanup_control_expr_graph (bb, bsi);
1885 /* Disconnect an unreachable block in the control expression starting
1889 cleanup_control_expr_graph (basic_block bb, block_stmt_iterator bsi)
1892 bool retval = false;
1893 tree expr = bsi_stmt (bsi), val;
1895 if (EDGE_COUNT (bb->succs) > 1)
1900 switch (TREE_CODE (expr))
1903 val = COND_EXPR_COND (expr);
1907 val = SWITCH_COND (expr);
1908 if (TREE_CODE (val) != INTEGER_CST)
1916 taken_edge = find_taken_edge (bb, val);
1920 /* Remove all the edges except the one that is always executed. */
1921 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
1923 if (e != taken_edge)
1925 taken_edge->probability += e->probability;
1926 taken_edge->count += e->count;
1927 ssa_remove_edge (e);
1933 if (taken_edge->probability > REG_BR_PROB_BASE)
1934 taken_edge->probability = REG_BR_PROB_BASE;
1937 taken_edge = EDGE_SUCC (bb, 0);
1940 taken_edge->flags = EDGE_FALLTHRU;
1942 /* We removed some paths from the cfg. */
1943 free_dominance_info (CDI_DOMINATORS);
1949 /* Given a control block BB and a predicate VAL, return the edge that
1950 will be taken out of the block. If VAL does not match a unique
1951 edge, NULL is returned. */
1954 find_taken_edge (basic_block bb, tree val)
1958 stmt = last_stmt (bb);
1961 gcc_assert (is_ctrl_stmt (stmt));
1963 /* If VAL is a predicate of the form N RELOP N, where N is an
1964 SSA_NAME, we can usually determine its truth value. */
1965 if (val && COMPARISON_CLASS_P (val))
1968 /* If VAL is not a constant, we can't determine which edge might
1970 if (val == NULL || !really_constant_p (val))
1973 if (TREE_CODE (stmt) == COND_EXPR)
1974 return find_taken_edge_cond_expr (bb, val);
1976 if (TREE_CODE (stmt) == SWITCH_EXPR)
1977 return find_taken_edge_switch_expr (bb, val);
1979 return EDGE_SUCC (bb, 0);
1983 /* Given a constant value VAL and the entry block BB to a COND_EXPR
1984 statement, determine which of the two edges will be taken out of the
1985 block. Return NULL if either edge may be taken. */
1988 find_taken_edge_cond_expr (basic_block bb, tree val)
1990 edge true_edge, false_edge;
1992 extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
1994 /* If both edges of the branch lead to the same basic block, it doesn't
1995 matter which edge is taken. */
1996 if (true_edge->dest == false_edge->dest)
1999 /* Otherwise, try to determine which branch of the if() will be taken.
2000 If VAL is a constant but it can't be reduced to a 0 or a 1, then
2001 we don't really know which edge will be taken at runtime. This
2002 may happen when comparing addresses (e.g., if (&var1 == 4)). */
2003 if (integer_nonzerop (val))
2005 else if (integer_zerop (val))
2012 /* Given a constant value VAL and the entry block BB to a SWITCH_EXPR
2013 statement, determine which edge will be taken out of the block. Return
2014 NULL if any edge may be taken. */
2017 find_taken_edge_switch_expr (basic_block bb, tree val)
2019 tree switch_expr, taken_case;
2020 basic_block dest_bb;
2023 if (TREE_CODE (val) != INTEGER_CST)
2026 switch_expr = last_stmt (bb);
2027 taken_case = find_case_label_for_value (switch_expr, val);
2028 dest_bb = label_to_block (CASE_LABEL (taken_case));
2030 e = find_edge (bb, dest_bb);
2036 /* Return the CASE_LABEL_EXPR that SWITCH_EXPR will take for VAL.
2037 We can make optimal use here of the fact that the case labels are
2038 sorted: We can do a binary search for a case matching VAL. */
2041 find_case_label_for_value (tree switch_expr, tree val)
2043 tree vec = SWITCH_LABELS (switch_expr);
2044 size_t low, high, n = TREE_VEC_LENGTH (vec);
2045 tree default_case = TREE_VEC_ELT (vec, n - 1);
2047 for (low = -1, high = n - 1; high - low > 1; )
2049 size_t i = (high + low) / 2;
2050 tree t = TREE_VEC_ELT (vec, i);
2053 /* Cache the result of comparing CASE_LOW and val. */
2054 cmp = tree_int_cst_compare (CASE_LOW (t), val);
2061 if (CASE_HIGH (t) == NULL)
2063 /* A singe-valued case label. */
2069 /* A case range. We can only handle integer ranges. */
2070 if (cmp <= 0 && tree_int_cst_compare (CASE_HIGH (t), val) >= 0)
2075 return default_case;
2079 /* If all the PHI nodes in DEST have alternatives for E1 and E2 and
2080 those alternatives are equal in each of the PHI nodes, then return
2081 true, else return false. */
2084 phi_alternatives_equal (basic_block dest, edge e1, edge e2)
2086 tree phi, val1, val2;
2089 for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi))
2091 n1 = phi_arg_from_edge (phi, e1);
2092 n2 = phi_arg_from_edge (phi, e2);
2094 gcc_assert (n1 >= 0);
2095 gcc_assert (n2 >= 0);
2097 val1 = PHI_ARG_DEF (phi, n1);
2098 val2 = PHI_ARG_DEF (phi, n2);
2100 if (!operand_equal_p (val1, val2, 0))
2108 /*---------------------------------------------------------------------------
2110 ---------------------------------------------------------------------------*/
2112 /* Dump tree-specific information of block BB to file OUTF. */
2115 tree_dump_bb (basic_block bb, FILE *outf, int indent)
2117 dump_generic_bb (outf, bb, indent, TDF_VOPS);
2121 /* Dump a basic block on stderr. */
2124 debug_tree_bb (basic_block bb)
2126 dump_bb (bb, stderr, 0);
2130 /* Dump basic block with index N on stderr. */
2133 debug_tree_bb_n (int n)
2135 debug_tree_bb (BASIC_BLOCK (n));
2136 return BASIC_BLOCK (n);
2140 /* Dump the CFG on stderr.
2142 FLAGS are the same used by the tree dumping functions
2143 (see TDF_* in tree.h). */
2146 debug_tree_cfg (int flags)
2148 dump_tree_cfg (stderr, flags);
2152 /* Dump the program showing basic block boundaries on the given FILE.
2154 FLAGS are the same used by the tree dumping functions (see TDF_* in
2158 dump_tree_cfg (FILE *file, int flags)
2160 if (flags & TDF_DETAILS)
2162 const char *funcname
2163 = lang_hooks.decl_printable_name (current_function_decl, 2);
2166 fprintf (file, ";; Function %s\n\n", funcname);
2167 fprintf (file, ";; \n%d basic blocks, %d edges, last basic block %d.\n\n",
2168 n_basic_blocks, n_edges, last_basic_block);
2170 brief_dump_cfg (file);
2171 fprintf (file, "\n");
2174 if (flags & TDF_STATS)
2175 dump_cfg_stats (file);
2177 dump_function_to_file (current_function_decl, file, flags | TDF_BLOCKS);
2181 /* Dump CFG statistics on FILE. */
2184 dump_cfg_stats (FILE *file)
2186 static long max_num_merged_labels = 0;
2187 unsigned long size, total = 0;
2190 const char * const fmt_str = "%-30s%-13s%12s\n";
2191 const char * const fmt_str_1 = "%-30s%13d%11lu%c\n";
2192 const char * const fmt_str_3 = "%-43s%11lu%c\n";
2193 const char *funcname
2194 = lang_hooks.decl_printable_name (current_function_decl, 2);
2197 fprintf (file, "\nCFG Statistics for %s\n\n", funcname);
2199 fprintf (file, "---------------------------------------------------------\n");
2200 fprintf (file, fmt_str, "", " Number of ", "Memory");
2201 fprintf (file, fmt_str, "", " instances ", "used ");
2202 fprintf (file, "---------------------------------------------------------\n");
2204 size = n_basic_blocks * sizeof (struct basic_block_def);
2206 fprintf (file, fmt_str_1, "Basic blocks", n_basic_blocks,
2207 SCALE (size), LABEL (size));
2211 n_edges += EDGE_COUNT (bb->succs);
2212 size = n_edges * sizeof (struct edge_def);
2214 fprintf (file, fmt_str_1, "Edges", n_edges, SCALE (size), LABEL (size));
2216 size = n_basic_blocks * sizeof (struct bb_ann_d);
2218 fprintf (file, fmt_str_1, "Basic block annotations", n_basic_blocks,
2219 SCALE (size), LABEL (size));
2221 fprintf (file, "---------------------------------------------------------\n");
2222 fprintf (file, fmt_str_3, "Total memory used by CFG data", SCALE (total),
2224 fprintf (file, "---------------------------------------------------------\n");
2225 fprintf (file, "\n");
2227 if (cfg_stats.num_merged_labels > max_num_merged_labels)
2228 max_num_merged_labels = cfg_stats.num_merged_labels;
2230 fprintf (file, "Coalesced label blocks: %ld (Max so far: %ld)\n",
2231 cfg_stats.num_merged_labels, max_num_merged_labels);
2233 fprintf (file, "\n");
2237 /* Dump CFG statistics on stderr. Keep extern so that it's always
2238 linked in the final executable. */
2241 debug_cfg_stats (void)
2243 dump_cfg_stats (stderr);
2247 /* Dump the flowgraph to a .vcg FILE. */
2250 tree_cfg2vcg (FILE *file)
2255 const char *funcname
2256 = lang_hooks.decl_printable_name (current_function_decl, 2);
2258 /* Write the file header. */
2259 fprintf (file, "graph: { title: \"%s\"\n", funcname);
2260 fprintf (file, "node: { title: \"ENTRY\" label: \"ENTRY\" }\n");
2261 fprintf (file, "node: { title: \"EXIT\" label: \"EXIT\" }\n");
2263 /* Write blocks and edges. */
2264 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
2266 fprintf (file, "edge: { sourcename: \"ENTRY\" targetname: \"%d\"",
2269 if (e->flags & EDGE_FAKE)
2270 fprintf (file, " linestyle: dotted priority: 10");
2272 fprintf (file, " linestyle: solid priority: 100");
2274 fprintf (file, " }\n");
2280 enum tree_code head_code, end_code;
2281 const char *head_name, *end_name;
2284 tree first = first_stmt (bb);
2285 tree last = last_stmt (bb);
2289 head_code = TREE_CODE (first);
2290 head_name = tree_code_name[head_code];
2291 head_line = get_lineno (first);
2294 head_name = "no-statement";
2298 end_code = TREE_CODE (last);
2299 end_name = tree_code_name[end_code];
2300 end_line = get_lineno (last);
2303 end_name = "no-statement";
2305 fprintf (file, "node: { title: \"%d\" label: \"#%d\\n%s (%d)\\n%s (%d)\"}\n",
2306 bb->index, bb->index, head_name, head_line, end_name,
2309 FOR_EACH_EDGE (e, ei, bb->succs)
2311 if (e->dest == EXIT_BLOCK_PTR)
2312 fprintf (file, "edge: { sourcename: \"%d\" targetname: \"EXIT\"", bb->index);
2314 fprintf (file, "edge: { sourcename: \"%d\" targetname: \"%d\"", bb->index, e->dest->index);
2316 if (e->flags & EDGE_FAKE)
2317 fprintf (file, " priority: 10 linestyle: dotted");
2319 fprintf (file, " priority: 100 linestyle: solid");
2321 fprintf (file, " }\n");
2324 if (bb->next_bb != EXIT_BLOCK_PTR)
2328 fputs ("}\n\n", file);
2333 /*---------------------------------------------------------------------------
2334 Miscellaneous helpers
2335 ---------------------------------------------------------------------------*/
2337 /* Return true if T represents a stmt that always transfers control. */
2340 is_ctrl_stmt (tree t)
2342 return (TREE_CODE (t) == COND_EXPR
2343 || TREE_CODE (t) == SWITCH_EXPR
2344 || TREE_CODE (t) == GOTO_EXPR
2345 || TREE_CODE (t) == RETURN_EXPR
2346 || TREE_CODE (t) == RESX_EXPR);
2350 /* Return true if T is a statement that may alter the flow of control
2351 (e.g., a call to a non-returning function). */
2354 is_ctrl_altering_stmt (tree t)
2359 call = get_call_expr_in (t);
2362 /* A non-pure/const CALL_EXPR alters flow control if the current
2363 function has nonlocal labels. */
2364 if (TREE_SIDE_EFFECTS (call) && current_function_has_nonlocal_label)
2367 /* A CALL_EXPR also alters control flow if it does not return. */
2368 if (call_expr_flags (call) & (ECF_NORETURN | ECF_LONGJMP))
2372 /* If a statement can throw, it alters control flow. */
2373 return tree_can_throw_internal (t);
2377 /* Return true if T is a computed goto. */
2380 computed_goto_p (tree t)
2382 return (TREE_CODE (t) == GOTO_EXPR
2383 && TREE_CODE (GOTO_DESTINATION (t)) != LABEL_DECL);
2387 /* Checks whether EXPR is a simple local goto. */
2390 simple_goto_p (tree expr)
2392 return (TREE_CODE (expr) == GOTO_EXPR
2393 && TREE_CODE (GOTO_DESTINATION (expr)) == LABEL_DECL);
2397 /* Return true if T should start a new basic block. PREV_T is the
2398 statement preceding T. It is used when T is a label or a case label.
2399 Labels should only start a new basic block if their previous statement
2400 wasn't a label. Otherwise, sequence of labels would generate
2401 unnecessary basic blocks that only contain a single label. */
2404 stmt_starts_bb_p (tree t, tree prev_t)
2406 enum tree_code code;
2411 /* LABEL_EXPRs start a new basic block only if the preceding
2412 statement wasn't a label of the same type. This prevents the
2413 creation of consecutive blocks that have nothing but a single
2415 code = TREE_CODE (t);
2416 if (code == LABEL_EXPR)
2418 /* Nonlocal and computed GOTO targets always start a new block. */
2419 if (code == LABEL_EXPR
2420 && (DECL_NONLOCAL (LABEL_EXPR_LABEL (t))
2421 || FORCED_LABEL (LABEL_EXPR_LABEL (t))))
2424 if (prev_t && TREE_CODE (prev_t) == code)
2426 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (prev_t)))
2429 cfg_stats.num_merged_labels++;
2440 /* Return true if T should end a basic block. */
2443 stmt_ends_bb_p (tree t)
2445 return is_ctrl_stmt (t) || is_ctrl_altering_stmt (t);
2449 /* Add gotos that used to be represented implicitly in the CFG. */
2452 disband_implicit_edges (void)
2455 block_stmt_iterator last;
2462 last = bsi_last (bb);
2463 stmt = last_stmt (bb);
2465 if (stmt && TREE_CODE (stmt) == COND_EXPR)
2467 /* Remove superfluous gotos from COND_EXPR branches. Moved
2468 from cfg_remove_useless_stmts here since it violates the
2469 invariants for tree--cfg correspondence and thus fits better
2470 here where we do it anyway. */
2471 FOR_EACH_EDGE (e, ei, bb->succs)
2473 if (e->dest != bb->next_bb)
2476 if (e->flags & EDGE_TRUE_VALUE)
2477 COND_EXPR_THEN (stmt) = build_empty_stmt ();
2478 else if (e->flags & EDGE_FALSE_VALUE)
2479 COND_EXPR_ELSE (stmt) = build_empty_stmt ();
2482 e->flags |= EDGE_FALLTHRU;
2488 if (stmt && TREE_CODE (stmt) == RETURN_EXPR)
2490 /* Remove the RETURN_EXPR if we may fall though to the exit
2492 gcc_assert (EDGE_COUNT (bb->succs) == 1);
2493 gcc_assert (EDGE_SUCC (bb, 0)->dest == EXIT_BLOCK_PTR);
2495 if (bb->next_bb == EXIT_BLOCK_PTR
2496 && !TREE_OPERAND (stmt, 0))
2499 EDGE_SUCC (bb, 0)->flags |= EDGE_FALLTHRU;
2504 /* There can be no fallthru edge if the last statement is a control
2506 if (stmt && is_ctrl_stmt (stmt))
2509 /* Find a fallthru edge and emit the goto if necessary. */
2510 FOR_EACH_EDGE (e, ei, bb->succs)
2511 if (e->flags & EDGE_FALLTHRU)
2514 if (!e || e->dest == bb->next_bb)
2517 gcc_assert (e->dest != EXIT_BLOCK_PTR);
2518 label = tree_block_label (e->dest);
2520 stmt = build1 (GOTO_EXPR, void_type_node, label);
2521 #ifdef USE_MAPPED_LOCATION
2522 SET_EXPR_LOCATION (stmt, e->goto_locus);
2524 SET_EXPR_LOCUS (stmt, e->goto_locus);
2526 bsi_insert_after (&last, stmt, BSI_NEW_STMT);
2527 e->flags &= ~EDGE_FALLTHRU;
2531 /* Remove block annotations and other datastructures. */
2534 delete_tree_cfg_annotations (void)
2537 if (n_basic_blocks > 0)
2538 free_blocks_annotations ();
2540 label_to_block_map = NULL;
2547 /* Return the first statement in basic block BB. */
2550 first_stmt (basic_block bb)
2552 block_stmt_iterator i = bsi_start (bb);
2553 return !bsi_end_p (i) ? bsi_stmt (i) : NULL_TREE;
2557 /* Return the last statement in basic block BB. */
2560 last_stmt (basic_block bb)
2562 block_stmt_iterator b = bsi_last (bb);
2563 return !bsi_end_p (b) ? bsi_stmt (b) : NULL_TREE;
2567 /* Return a pointer to the last statement in block BB. */
2570 last_stmt_ptr (basic_block bb)
2572 block_stmt_iterator last = bsi_last (bb);
2573 return !bsi_end_p (last) ? bsi_stmt_ptr (last) : NULL;
2577 /* Return the last statement of an otherwise empty block. Return NULL
2578 if the block is totally empty, or if it contains more than one
2582 last_and_only_stmt (basic_block bb)
2584 block_stmt_iterator i = bsi_last (bb);
2590 last = bsi_stmt (i);
2595 /* Empty statements should no longer appear in the instruction stream.
2596 Everything that might have appeared before should be deleted by
2597 remove_useless_stmts, and the optimizers should just bsi_remove
2598 instead of smashing with build_empty_stmt.
2600 Thus the only thing that should appear here in a block containing
2601 one executable statement is a label. */
2602 prev = bsi_stmt (i);
2603 if (TREE_CODE (prev) == LABEL_EXPR)
2610 /* Mark BB as the basic block holding statement T. */
2613 set_bb_for_stmt (tree t, basic_block bb)
2615 if (TREE_CODE (t) == PHI_NODE)
2617 else if (TREE_CODE (t) == STATEMENT_LIST)
2619 tree_stmt_iterator i;
2620 for (i = tsi_start (t); !tsi_end_p (i); tsi_next (&i))
2621 set_bb_for_stmt (tsi_stmt (i), bb);
2625 stmt_ann_t ann = get_stmt_ann (t);
2628 /* If the statement is a label, add the label to block-to-labels map
2629 so that we can speed up edge creation for GOTO_EXPRs. */
2630 if (TREE_CODE (t) == LABEL_EXPR)
2634 t = LABEL_EXPR_LABEL (t);
2635 uid = LABEL_DECL_UID (t);
2638 LABEL_DECL_UID (t) = uid = cfun->last_label_uid++;
2639 if (VARRAY_SIZE (label_to_block_map) <= (unsigned) uid)
2640 VARRAY_GROW (label_to_block_map, 3 * uid / 2);
2643 /* We're moving an existing label. Make sure that we've
2644 removed it from the old block. */
2645 gcc_assert (!bb || !VARRAY_BB (label_to_block_map, uid));
2646 VARRAY_BB (label_to_block_map, uid) = bb;
2651 /* Finds iterator for STMT. */
2653 extern block_stmt_iterator
2654 bsi_for_stmt (tree stmt)
2656 block_stmt_iterator bsi;
2658 for (bsi = bsi_start (bb_for_stmt (stmt)); !bsi_end_p (bsi); bsi_next (&bsi))
2659 if (bsi_stmt (bsi) == stmt)
2665 /* Insert statement (or statement list) T before 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_before (block_stmt_iterator *i, tree t, enum bsi_iterator_update m)
2672 set_bb_for_stmt (t, i->bb);
2673 tsi_link_before (&i->tsi, t, m);
2678 /* Insert statement (or statement list) T after the statement
2679 pointed-to by iterator I. M specifies how to update iterator I
2680 after insertion (see enum bsi_iterator_update). */
2683 bsi_insert_after (block_stmt_iterator *i, tree t, enum bsi_iterator_update m)
2685 set_bb_for_stmt (t, i->bb);
2686 tsi_link_after (&i->tsi, t, m);
2691 /* Remove the statement pointed to by iterator I. The iterator is updated
2692 to the next statement. */
2695 bsi_remove (block_stmt_iterator *i)
2697 tree t = bsi_stmt (*i);
2698 set_bb_for_stmt (t, NULL);
2699 tsi_delink (&i->tsi);
2703 /* Move the statement at FROM so it comes right after the statement at TO. */
2706 bsi_move_after (block_stmt_iterator *from, block_stmt_iterator *to)
2708 tree stmt = bsi_stmt (*from);
2710 bsi_insert_after (to, stmt, BSI_SAME_STMT);
2714 /* Move the statement at FROM so it comes right before the statement at TO. */
2717 bsi_move_before (block_stmt_iterator *from, block_stmt_iterator *to)
2719 tree stmt = bsi_stmt (*from);
2721 bsi_insert_before (to, stmt, BSI_SAME_STMT);
2725 /* Move the statement at FROM to the end of basic block BB. */
2728 bsi_move_to_bb_end (block_stmt_iterator *from, basic_block bb)
2730 block_stmt_iterator last = bsi_last (bb);
2732 /* Have to check bsi_end_p because it could be an empty block. */
2733 if (!bsi_end_p (last) && is_ctrl_stmt (bsi_stmt (last)))
2734 bsi_move_before (from, &last);
2736 bsi_move_after (from, &last);
2740 /* Replace the contents of the statement pointed to by iterator BSI
2741 with STMT. If PRESERVE_EH_INFO is true, the exception handling
2742 information of the original statement is preserved. */
2745 bsi_replace (const block_stmt_iterator *bsi, tree stmt, bool preserve_eh_info)
2748 tree orig_stmt = bsi_stmt (*bsi);
2750 SET_EXPR_LOCUS (stmt, EXPR_LOCUS (orig_stmt));
2751 set_bb_for_stmt (stmt, bsi->bb);
2753 /* Preserve EH region information from the original statement, if
2754 requested by the caller. */
2755 if (preserve_eh_info)
2757 eh_region = lookup_stmt_eh_region (orig_stmt);
2759 add_stmt_to_eh_region (stmt, eh_region);
2762 *bsi_stmt_ptr (*bsi) = stmt;
2767 /* Insert the statement pointed-to by BSI into edge E. Every attempt
2768 is made to place the statement in an existing basic block, but
2769 sometimes that isn't possible. When it isn't possible, the edge is
2770 split and the statement is added to the new block.
2772 In all cases, the returned *BSI points to the correct location. The
2773 return value is true if insertion should be done after the location,
2774 or false if it should be done before the location. If new basic block
2775 has to be created, it is stored in *NEW_BB. */
2778 tree_find_edge_insert_loc (edge e, block_stmt_iterator *bsi,
2779 basic_block *new_bb)
2781 basic_block dest, src;
2787 /* If the destination has one predecessor which has no PHI nodes,
2788 insert there. Except for the exit block.
2790 The requirement for no PHI nodes could be relaxed. Basically we
2791 would have to examine the PHIs to prove that none of them used
2792 the value set by the statement we want to insert on E. That
2793 hardly seems worth the effort. */
2794 if (EDGE_COUNT (dest->preds) == 1
2795 && ! phi_nodes (dest)
2796 && dest != EXIT_BLOCK_PTR)
2798 *bsi = bsi_start (dest);
2799 if (bsi_end_p (*bsi))
2802 /* Make sure we insert after any leading labels. */
2803 tmp = bsi_stmt (*bsi);
2804 while (TREE_CODE (tmp) == LABEL_EXPR)
2807 if (bsi_end_p (*bsi))
2809 tmp = bsi_stmt (*bsi);
2812 if (bsi_end_p (*bsi))
2814 *bsi = bsi_last (dest);
2821 /* If the source has one successor, the edge is not abnormal and
2822 the last statement does not end a basic block, insert there.
2823 Except for the entry block. */
2825 if ((e->flags & EDGE_ABNORMAL) == 0
2826 && EDGE_COUNT (src->succs) == 1
2827 && src != ENTRY_BLOCK_PTR)
2829 *bsi = bsi_last (src);
2830 if (bsi_end_p (*bsi))
2833 tmp = bsi_stmt (*bsi);
2834 if (!stmt_ends_bb_p (tmp))
2837 /* Insert code just before returning the value. We may need to decompose
2838 the return in the case it contains non-trivial operand. */
2839 if (TREE_CODE (tmp) == RETURN_EXPR)
2841 tree op = TREE_OPERAND (tmp, 0);
2842 if (!is_gimple_val (op))
2844 gcc_assert (TREE_CODE (op) == MODIFY_EXPR);
2845 bsi_insert_before (bsi, op, BSI_NEW_STMT);
2846 TREE_OPERAND (tmp, 0) = TREE_OPERAND (op, 0);
2853 /* Otherwise, create a new basic block, and split this edge. */
2854 dest = split_edge (e);
2857 e = EDGE_PRED (dest, 0);
2862 /* This routine will commit all pending edge insertions, creating any new
2863 basic blocks which are necessary.
2865 If specified, NEW_BLOCKS returns a count of the number of new basic
2866 blocks which were created. */
2869 bsi_commit_edge_inserts (int *new_blocks)
2876 blocks = n_basic_blocks;
2878 bsi_commit_edge_inserts_1 (EDGE_SUCC (ENTRY_BLOCK_PTR, 0));
2881 FOR_EACH_EDGE (e, ei, bb->succs)
2882 bsi_commit_edge_inserts_1 (e);
2885 *new_blocks = n_basic_blocks - blocks;
2889 /* Commit insertions pending at edge E. */
2892 bsi_commit_edge_inserts_1 (edge e)
2894 if (PENDING_STMT (e))
2896 block_stmt_iterator bsi;
2897 tree stmt = PENDING_STMT (e);
2899 PENDING_STMT (e) = NULL_TREE;
2901 if (tree_find_edge_insert_loc (e, &bsi, NULL))
2902 bsi_insert_after (&bsi, stmt, BSI_NEW_STMT);
2904 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
2909 /* Add STMT to the pending list of edge E. No actual insertion is
2910 made until a call to bsi_commit_edge_inserts () is made. */
2913 bsi_insert_on_edge (edge e, tree stmt)
2915 append_to_statement_list (stmt, &PENDING_STMT (e));
2918 /* Similar to bsi_insert_on_edge+bsi_commit_edge_inserts. If new block has to
2919 be created, it is returned. */
2922 bsi_insert_on_edge_immediate (edge e, tree stmt)
2924 block_stmt_iterator bsi;
2925 basic_block new_bb = NULL;
2927 gcc_assert (!PENDING_STMT (e));
2929 if (tree_find_edge_insert_loc (e, &bsi, &new_bb))
2930 bsi_insert_after (&bsi, stmt, BSI_NEW_STMT);
2932 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
2937 /*---------------------------------------------------------------------------
2938 Tree specific functions for CFG manipulation
2939 ---------------------------------------------------------------------------*/
2941 /* Split a (typically critical) edge EDGE_IN. Return the new block.
2942 Abort on abnormal edges. */
2945 tree_split_edge (edge edge_in)
2947 basic_block new_bb, after_bb, dest, src;
2953 /* Abnormal edges cannot be split. */
2954 gcc_assert (!(edge_in->flags & EDGE_ABNORMAL));
2957 dest = edge_in->dest;
2959 /* Place the new block in the block list. Try to keep the new block
2960 near its "logical" location. This is of most help to humans looking
2961 at debugging dumps. */
2962 FOR_EACH_EDGE (e, ei, dest->preds)
2963 if (e->src->next_bb == dest)
2966 after_bb = dest->prev_bb;
2968 after_bb = edge_in->src;
2970 new_bb = create_empty_bb (after_bb);
2971 new_bb->frequency = EDGE_FREQUENCY (edge_in);
2972 new_bb->count = edge_in->count;
2973 new_edge = make_edge (new_bb, dest, EDGE_FALLTHRU);
2974 new_edge->probability = REG_BR_PROB_BASE;
2975 new_edge->count = edge_in->count;
2977 /* Find all the PHI arguments on the original edge, and change them to
2978 the new edge. Do it before redirection, so that the argument does not
2980 for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi))
2982 num_elem = PHI_NUM_ARGS (phi);
2983 for (i = 0; i < num_elem; i++)
2984 if (PHI_ARG_EDGE (phi, i) == edge_in)
2986 PHI_ARG_EDGE (phi, i) = new_edge;
2991 e = redirect_edge_and_branch (edge_in, new_bb);
2993 gcc_assert (!PENDING_STMT (edge_in));
2999 /* Return true when BB has label LABEL in it. */
3002 has_label_p (basic_block bb, tree label)
3004 block_stmt_iterator bsi;
3006 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3008 tree stmt = bsi_stmt (bsi);
3010 if (TREE_CODE (stmt) != LABEL_EXPR)
3012 if (LABEL_EXPR_LABEL (stmt) == label)
3019 /* Callback for walk_tree, check that all elements with address taken are
3020 properly noticed as such. */
3023 verify_expr (tree *tp, int *walk_subtrees, void *data ATTRIBUTE_UNUSED)
3030 /* Check operand N for being valid GIMPLE and give error MSG if not.
3031 We check for constants explicitly since they are not considered
3032 gimple invariants if they overflowed. */
3033 #define CHECK_OP(N, MSG) \
3034 do { if (!CONSTANT_CLASS_P (TREE_OPERAND (t, N)) \
3035 && !is_gimple_val (TREE_OPERAND (t, N))) \
3036 { error (MSG); return TREE_OPERAND (t, N); }} while (0)
3038 switch (TREE_CODE (t))
3041 if (SSA_NAME_IN_FREE_LIST (t))
3043 error ("SSA name in freelist but still referenced");
3049 x = TREE_OPERAND (t, 0);
3050 if (TREE_CODE (x) == BIT_FIELD_REF
3051 && is_gimple_reg (TREE_OPERAND (x, 0)))
3053 error ("GIMPLE register modified with BIT_FIELD_REF");
3059 /* Skip any references (they will be checked when we recurse down the
3060 tree) and ensure that any variable used as a prefix is marked
3062 for (x = TREE_OPERAND (t, 0);
3063 (handled_component_p (x)
3064 || TREE_CODE (x) == REALPART_EXPR
3065 || TREE_CODE (x) == IMAGPART_EXPR);
3066 x = TREE_OPERAND (x, 0))
3069 if (TREE_CODE (x) != VAR_DECL && TREE_CODE (x) != PARM_DECL)
3071 if (!TREE_ADDRESSABLE (x))
3073 error ("address taken, but ADDRESSABLE bit not set");
3079 x = TREE_OPERAND (t, 0);
3080 if (TREE_CODE (TREE_TYPE (x)) != BOOLEAN_TYPE)
3082 error ("non-boolean used in condition");
3089 case FIX_TRUNC_EXPR:
3091 case FIX_FLOOR_EXPR:
3092 case FIX_ROUND_EXPR:
3097 case NON_LVALUE_EXPR:
3098 case TRUTH_NOT_EXPR:
3099 CHECK_OP (0, "Invalid operand to unary operator");
3106 case ARRAY_RANGE_REF:
3108 case VIEW_CONVERT_EXPR:
3109 /* We have a nest of references. Verify that each of the operands
3110 that determine where to reference is either a constant or a variable,
3111 verify that the base is valid, and then show we've already checked
3113 while (TREE_CODE (t) == REALPART_EXPR || TREE_CODE (t) == IMAGPART_EXPR
3114 || handled_component_p (t))
3116 if (TREE_CODE (t) == COMPONENT_REF && TREE_OPERAND (t, 2))
3117 CHECK_OP (2, "Invalid COMPONENT_REF offset operator");
3118 else if (TREE_CODE (t) == ARRAY_REF
3119 || TREE_CODE (t) == ARRAY_RANGE_REF)
3121 CHECK_OP (1, "Invalid array index.");
3122 if (TREE_OPERAND (t, 2))
3123 CHECK_OP (2, "Invalid array lower bound.");
3124 if (TREE_OPERAND (t, 3))
3125 CHECK_OP (3, "Invalid array stride.");
3127 else if (TREE_CODE (t) == BIT_FIELD_REF)
3129 CHECK_OP (1, "Invalid operand to BIT_FIELD_REF");
3130 CHECK_OP (2, "Invalid operand to BIT_FIELD_REF");
3133 t = TREE_OPERAND (t, 0);
3136 if (!CONSTANT_CLASS_P (t) && !is_gimple_lvalue (t))
3138 error ("Invalid reference prefix.");
3150 case UNORDERED_EXPR:
3161 case TRUNC_DIV_EXPR:
3163 case FLOOR_DIV_EXPR:
3164 case ROUND_DIV_EXPR:
3165 case TRUNC_MOD_EXPR:
3167 case FLOOR_MOD_EXPR:
3168 case ROUND_MOD_EXPR:
3170 case EXACT_DIV_EXPR:
3180 CHECK_OP (0, "Invalid operand to binary operator");
3181 CHECK_OP (1, "Invalid operand to binary operator");
3193 /* Verify STMT, return true if STMT is not in GIMPLE form.
3194 TODO: Implement type checking. */
3197 verify_stmt (tree stmt, bool last_in_block)
3201 if (!is_gimple_stmt (stmt))
3203 error ("Is not a valid GIMPLE statement.");
3207 addr = walk_tree (&stmt, verify_expr, NULL, NULL);
3210 debug_generic_stmt (addr);
3214 /* If the statement is marked as part of an EH region, then it is
3215 expected that the statement could throw. Verify that when we
3216 have optimizations that simplify statements such that we prove
3217 that they cannot throw, that we update other data structures
3219 if (lookup_stmt_eh_region (stmt) >= 0)
3221 if (!tree_could_throw_p (stmt))
3223 error ("Statement marked for throw, but doesn%'t.");
3226 if (!last_in_block && tree_can_throw_internal (stmt))
3228 error ("Statement marked for throw in middle of block.");
3236 debug_generic_stmt (stmt);
3241 /* Return true when the T can be shared. */
3244 tree_node_can_be_shared (tree t)
3246 if (IS_TYPE_OR_DECL_P (t)
3247 /* We check for constants explicitly since they are not considered
3248 gimple invariants if they overflowed. */
3249 || CONSTANT_CLASS_P (t)
3250 || is_gimple_min_invariant (t)
3251 || TREE_CODE (t) == SSA_NAME)
3254 while (((TREE_CODE (t) == ARRAY_REF || TREE_CODE (t) == ARRAY_RANGE_REF)
3255 /* We check for constants explicitly since they are not considered
3256 gimple invariants if they overflowed. */
3257 && (CONSTANT_CLASS_P (TREE_OPERAND (t, 1))
3258 || is_gimple_min_invariant (TREE_OPERAND (t, 1))))
3259 || (TREE_CODE (t) == COMPONENT_REF
3260 || TREE_CODE (t) == REALPART_EXPR
3261 || TREE_CODE (t) == IMAGPART_EXPR))
3262 t = TREE_OPERAND (t, 0);
3271 /* Called via walk_trees. Verify tree sharing. */
3274 verify_node_sharing (tree * tp, int *walk_subtrees, void *data)
3276 htab_t htab = (htab_t) data;
3279 if (tree_node_can_be_shared (*tp))
3281 *walk_subtrees = false;
3285 slot = htab_find_slot (htab, *tp, INSERT);
3294 /* Verify the GIMPLE statement chain. */
3300 block_stmt_iterator bsi;
3305 timevar_push (TV_TREE_STMT_VERIFY);
3306 htab = htab_create (37, htab_hash_pointer, htab_eq_pointer, NULL);
3313 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
3315 int phi_num_args = PHI_NUM_ARGS (phi);
3317 for (i = 0; i < phi_num_args; i++)
3319 tree t = PHI_ARG_DEF (phi, i);
3322 /* Addressable variables do have SSA_NAMEs but they
3323 are not considered gimple values. */
3324 if (TREE_CODE (t) != SSA_NAME
3325 && TREE_CODE (t) != FUNCTION_DECL
3326 && !is_gimple_val (t))
3328 error ("PHI def is not a GIMPLE value");
3329 debug_generic_stmt (phi);
3330 debug_generic_stmt (t);
3334 addr = walk_tree (&t, verify_expr, NULL, NULL);
3337 debug_generic_stmt (addr);
3341 addr = walk_tree (&t, verify_node_sharing, htab, NULL);
3344 error ("Incorrect sharing of tree nodes");
3345 debug_generic_stmt (phi);
3346 debug_generic_stmt (addr);
3352 for (bsi = bsi_start (bb); !bsi_end_p (bsi); )
3354 tree stmt = bsi_stmt (bsi);
3356 err |= verify_stmt (stmt, bsi_end_p (bsi));
3357 addr = walk_tree (&stmt, verify_node_sharing, htab, NULL);
3360 error ("Incorrect sharing of tree nodes");
3361 debug_generic_stmt (stmt);
3362 debug_generic_stmt (addr);
3369 internal_error ("verify_stmts failed.");
3372 timevar_pop (TV_TREE_STMT_VERIFY);
3376 /* Verifies that the flow information is OK. */
3379 tree_verify_flow_info (void)
3383 block_stmt_iterator bsi;
3388 if (ENTRY_BLOCK_PTR->stmt_list)
3390 error ("ENTRY_BLOCK has a statement list associated with it\n");
3394 if (EXIT_BLOCK_PTR->stmt_list)
3396 error ("EXIT_BLOCK has a statement list associated with it\n");
3400 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
3401 if (e->flags & EDGE_FALLTHRU)
3403 error ("Fallthru to exit from bb %d\n", e->src->index);
3409 bool found_ctrl_stmt = false;
3411 /* Skip labels on the start of basic block. */
3412 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3414 if (TREE_CODE (bsi_stmt (bsi)) != LABEL_EXPR)
3417 if (label_to_block (LABEL_EXPR_LABEL (bsi_stmt (bsi))) != bb)
3419 tree stmt = bsi_stmt (bsi);
3420 error ("Label %s to block does not match in bb %d\n",
3421 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt))),
3426 if (decl_function_context (LABEL_EXPR_LABEL (bsi_stmt (bsi)))
3427 != current_function_decl)
3429 tree stmt = bsi_stmt (bsi);
3430 error ("Label %s has incorrect context in bb %d\n",
3431 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt))),
3437 /* Verify that body of basic block BB is free of control flow. */
3438 for (; !bsi_end_p (bsi); bsi_next (&bsi))
3440 tree stmt = bsi_stmt (bsi);
3442 if (found_ctrl_stmt)
3444 error ("Control flow in the middle of basic block %d\n",
3449 if (stmt_ends_bb_p (stmt))
3450 found_ctrl_stmt = true;
3452 if (TREE_CODE (stmt) == LABEL_EXPR)
3454 error ("Label %s in the middle of basic block %d\n",
3455 IDENTIFIER_POINTER (DECL_NAME (stmt)),
3460 bsi = bsi_last (bb);
3461 if (bsi_end_p (bsi))
3464 stmt = bsi_stmt (bsi);
3466 if (is_ctrl_stmt (stmt))
3468 FOR_EACH_EDGE (e, ei, bb->succs)
3469 if (e->flags & EDGE_FALLTHRU)
3471 error ("Fallthru edge after a control statement in bb %d \n",
3477 switch (TREE_CODE (stmt))
3483 if (TREE_CODE (COND_EXPR_THEN (stmt)) != GOTO_EXPR
3484 || TREE_CODE (COND_EXPR_ELSE (stmt)) != GOTO_EXPR)
3486 error ("Structured COND_EXPR at the end of bb %d\n", bb->index);
3490 extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
3492 if (!true_edge || !false_edge
3493 || !(true_edge->flags & EDGE_TRUE_VALUE)
3494 || !(false_edge->flags & EDGE_FALSE_VALUE)
3495 || (true_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL))
3496 || (false_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL))
3497 || EDGE_COUNT (bb->succs) >= 3)
3499 error ("Wrong outgoing edge flags at end of bb %d\n",
3504 if (!has_label_p (true_edge->dest,
3505 GOTO_DESTINATION (COND_EXPR_THEN (stmt))))
3507 error ("%<then%> label does not match edge at end of bb %d\n",
3512 if (!has_label_p (false_edge->dest,
3513 GOTO_DESTINATION (COND_EXPR_ELSE (stmt))))
3515 error ("%<else%> label does not match edge at end of bb %d\n",
3523 if (simple_goto_p (stmt))
3525 error ("Explicit goto at end of bb %d\n", bb->index);
3530 /* FIXME. We should double check that the labels in the
3531 destination blocks have their address taken. */
3532 FOR_EACH_EDGE (e, ei, bb->succs)
3533 if ((e->flags & (EDGE_FALLTHRU | EDGE_TRUE_VALUE
3534 | EDGE_FALSE_VALUE))
3535 || !(e->flags & EDGE_ABNORMAL))
3537 error ("Wrong outgoing edge flags at end of bb %d\n",
3545 if (EDGE_COUNT (bb->succs) != 1
3546 || (EDGE_SUCC (bb, 0)->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL
3547 | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
3549 error ("Wrong outgoing edge flags at end of bb %d\n", bb->index);
3552 if (EDGE_SUCC (bb, 0)->dest != EXIT_BLOCK_PTR)
3554 error ("Return edge does not point to exit in bb %d\n",
3567 vec = SWITCH_LABELS (stmt);
3568 n = TREE_VEC_LENGTH (vec);
3570 /* Mark all the destination basic blocks. */
3571 for (i = 0; i < n; ++i)
3573 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
3574 basic_block label_bb = label_to_block (lab);
3576 gcc_assert (!label_bb->aux || label_bb->aux == (void *)1);
3577 label_bb->aux = (void *)1;
3580 /* Verify that the case labels are sorted. */
3581 prev = TREE_VEC_ELT (vec, 0);
3582 for (i = 1; i < n - 1; ++i)
3584 tree c = TREE_VEC_ELT (vec, i);
3587 error ("Found default case not at end of case vector");
3591 if (! tree_int_cst_lt (CASE_LOW (prev), CASE_LOW (c)))
3593 error ("Case labels not sorted:\n ");
3594 print_generic_expr (stderr, prev, 0);
3595 fprintf (stderr," is greater than ");
3596 print_generic_expr (stderr, c, 0);
3597 fprintf (stderr," but comes before it.\n");
3602 if (CASE_LOW (TREE_VEC_ELT (vec, n - 1)))
3604 error ("No default case found at end of case vector");
3608 FOR_EACH_EDGE (e, ei, bb->succs)
3612 error ("Extra outgoing edge %d->%d\n",
3613 bb->index, e->dest->index);
3616 e->dest->aux = (void *)2;
3617 if ((e->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL
3618 | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
3620 error ("Wrong outgoing edge flags at end of bb %d\n",
3626 /* Check that we have all of them. */
3627 for (i = 0; i < n; ++i)
3629 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
3630 basic_block label_bb = label_to_block (lab);
3632 if (label_bb->aux != (void *)2)
3634 error ("Missing edge %i->%i\n",
3635 bb->index, label_bb->index);
3640 FOR_EACH_EDGE (e, ei, bb->succs)
3641 e->dest->aux = (void *)0;
3648 if (dom_computed[CDI_DOMINATORS] >= DOM_NO_FAST_QUERY)
3649 verify_dominators (CDI_DOMINATORS);
3655 /* Updates phi nodes after creating a forwarder block joined
3656 by edge FALLTHRU. */
3659 tree_make_forwarder_block (edge fallthru)
3663 basic_block dummy, bb;
3664 tree phi, new_phi, var, prev, next;
3666 dummy = fallthru->src;
3667 bb = fallthru->dest;
3669 if (EDGE_COUNT (bb->preds) == 1)
3672 /* If we redirected a branch we must create new phi nodes at the
3674 for (phi = phi_nodes (dummy); phi; phi = PHI_CHAIN (phi))
3676 var = PHI_RESULT (phi);
3677 new_phi = create_phi_node (var, bb);
3678 SSA_NAME_DEF_STMT (var) = new_phi;
3679 SET_PHI_RESULT (phi, make_ssa_name (SSA_NAME_VAR (var), phi));
3680 add_phi_arg (&new_phi, PHI_RESULT (phi), fallthru);
3683 /* Ensure that the PHI node chain is in the same order. */
3685 for (phi = phi_nodes (bb); phi; phi = next)
3687 next = PHI_CHAIN (phi);
3688 PHI_CHAIN (phi) = prev;
3691 set_phi_nodes (bb, prev);
3693 /* Add the arguments we have stored on edges. */
3694 FOR_EACH_EDGE (e, ei, bb->preds)
3699 for (phi = phi_nodes (bb), var = PENDING_STMT (e);
3701 phi = PHI_CHAIN (phi), var = TREE_CHAIN (var))
3702 add_phi_arg (&phi, TREE_VALUE (var), e);
3704 PENDING_STMT (e) = NULL;
3709 /* Return true if basic block BB does nothing except pass control
3710 flow to another block and that we can safely insert a label at
3711 the start of the successor block.
3713 As a precondition, we require that BB be not equal to
3717 tree_forwarder_block_p (basic_block bb)
3719 block_stmt_iterator bsi;
3723 /* BB must have a single outgoing edge. */
3724 if (EDGE_COUNT (bb->succs) != 1
3725 /* BB can not have any PHI nodes. This could potentially be
3726 relaxed early in compilation if we re-rewrote the variables
3727 appearing in any PHI nodes in forwarder blocks. */
3729 /* BB may not be a predecessor of EXIT_BLOCK_PTR. */
3730 || EDGE_SUCC (bb, 0)->dest == EXIT_BLOCK_PTR
3731 /* BB may not have an abnormal outgoing edge. */
3732 || (EDGE_SUCC (bb, 0)->flags & EDGE_ABNORMAL))
3736 gcc_assert (bb != ENTRY_BLOCK_PTR);
3739 /* Successors of the entry block are not forwarders. */
3740 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
3744 /* Now walk through the statements. We can ignore labels, anything else
3745 means this is not a forwarder block. */
3746 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3748 tree stmt = bsi_stmt (bsi);
3750 switch (TREE_CODE (stmt))
3753 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)))
3766 /* Thread jumps over empty statements.
3768 This code should _not_ thread over obviously equivalent conditions
3769 as that requires nontrivial updates to the SSA graph.
3771 As a precondition, we require that all basic blocks be reachable.
3772 That is, there should be no opportunities left for
3773 delete_unreachable_blocks. */
3779 basic_block bb, dest, tmp, old_dest, curr, dom;
3782 bool retval = false;
3785 bb_ann (bb)->forwardable = tree_forwarder_block_p (bb);
3790 bool this_jump_threaded = false;
3792 /* Don't waste time on forwarders. */
3793 if (bb_ann (bb)->forwardable)
3796 /* Examine each of our block's successors to see if it is
3798 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
3803 /* If the edge is abnormal or its destination is not
3804 forwardable, then there's nothing to do. */
3805 if ((e->flags & EDGE_ABNORMAL)
3806 || !bb_ann (e->dest)->forwardable)
3813 freq = EDGE_FREQUENCY (e);
3815 /* Now walk through as many forwarder blocks as possible to
3816 find the ultimate destination we want to thread our jump
3818 last = EDGE_SUCC (e->dest, 0);
3819 bb_ann (e->dest)->forwardable = 0;
3820 for (dest = EDGE_SUCC (e->dest, 0)->dest;
3821 bb_ann (dest)->forwardable;
3822 last = EDGE_SUCC (dest, 0),
3823 dest = EDGE_SUCC (dest, 0)->dest)
3824 bb_ann (dest)->forwardable = 0;
3826 /* Reset the forwardable marks to 1. */
3829 tmp = EDGE_SUCC (tmp, 0)->dest)
3830 bb_ann (tmp)->forwardable = 1;
3832 if (dest == e->dest)
3838 old = find_edge (bb, dest);
3841 /* If there already is an edge, check whether the values
3842 in phi nodes differ. */
3843 if (!phi_alternatives_equal (dest, last, old))
3845 /* The previous block is forwarder. Redirect our jump
3846 to that target instead since we know it has no PHI
3847 nodes that will need updating. */
3850 /* That might mean that no forwarding at all is possible. */
3851 if (dest == e->dest)
3857 old = find_edge (bb, dest);
3861 /* Perform the redirection. */
3862 retval = this_jump_threaded = true;
3864 e = redirect_edge_and_branch (e, dest);
3866 /* Update the profile. */
3867 if (profile_status != PROFILE_ABSENT)
3868 for (curr = old_dest; curr != dest; curr = EDGE_SUCC (curr, 0)->dest)
3870 curr->frequency -= freq;
3871 if (curr->frequency < 0)
3872 curr->frequency = 0;
3873 curr->count -= count;
3874 if (curr->count < 0)
3876 EDGE_SUCC (curr, 0)->count -= count;
3877 if (EDGE_SUCC (curr, 0)->count < 0)
3878 EDGE_SUCC (curr, 0)->count = 0;
3883 /* Update PHI nodes. We know that the new argument should
3884 have the same value as the argument associated with LAST.
3885 Otherwise we would have changed our target block above. */
3886 for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi))
3888 arg = phi_arg_from_edge (phi, last);
3889 gcc_assert (arg >= 0);
3890 add_phi_arg (&phi, PHI_ARG_DEF (phi, arg), e);
3894 /* Remove the unreachable blocks (observe that if all blocks
3895 were reachable before, only those in the path we threaded
3896 over and did not have any predecessor outside of the path
3897 become unreachable). */
3898 for (; old_dest != dest; old_dest = tmp)
3900 tmp = EDGE_SUCC (old_dest, 0)->dest;
3902 if (EDGE_COUNT (old_dest->preds) > 0)
3905 delete_basic_block (old_dest);
3908 /* Update the dominators. */
3909 if (dom_info_available_p (CDI_DOMINATORS))
3911 /* If the dominator of the destination was in the path, set its
3912 dominator to the start of the redirected edge. */
3913 if (get_immediate_dominator (CDI_DOMINATORS, old_dest) == NULL)
3914 set_immediate_dominator (CDI_DOMINATORS, old_dest, bb);
3916 /* Now proceed like if we forwarded just over one edge at a time.
3917 Algorithm for forwarding edge S --> A over edge A --> B then
3921 && !dominated_by (S, B))
3922 idom (B) = idom (A);
3923 recount_idom (A); */
3925 for (; old_dest != dest; old_dest = tmp)
3927 tmp = EDGE_SUCC (old_dest, 0)->dest;
3929 if (get_immediate_dominator (CDI_DOMINATORS, tmp) == old_dest
3930 && !dominated_by_p (CDI_DOMINATORS, bb, tmp))
3932 dom = get_immediate_dominator (CDI_DOMINATORS, old_dest);
3933 set_immediate_dominator (CDI_DOMINATORS, tmp, dom);
3936 dom = recount_dominator (CDI_DOMINATORS, old_dest);
3937 set_immediate_dominator (CDI_DOMINATORS, old_dest, dom);
3942 /* If we succeeded in threading a jump at BB, update the
3943 forwardable mark as BB may have become a new forwarder block.
3944 This could happen if we have a useless "if" statement whose
3945 two arms eventually merge without any intervening
3947 if (this_jump_threaded && tree_forwarder_block_p (bb))
3948 bb_ann (bb)->forwardable = true;
3955 /* Return a non-special label in the head of basic block BLOCK.
3956 Create one if it doesn't exist. */
3959 tree_block_label (basic_block bb)
3961 block_stmt_iterator i, s = bsi_start (bb);
3965 for (i = s; !bsi_end_p (i); first = false, bsi_next (&i))
3967 stmt = bsi_stmt (i);
3968 if (TREE_CODE (stmt) != LABEL_EXPR)
3970 label = LABEL_EXPR_LABEL (stmt);
3971 if (!DECL_NONLOCAL (label))
3974 bsi_move_before (&i, &s);
3979 label = create_artificial_label ();
3980 stmt = build1 (LABEL_EXPR, void_type_node, label);
3981 bsi_insert_before (&s, stmt, BSI_NEW_STMT);
3986 /* Attempt to perform edge redirection by replacing a possibly complex
3987 jump instruction by a goto or by removing the jump completely.
3988 This can apply only if all edges now point to the same block. The
3989 parameters and return values are equivalent to
3990 redirect_edge_and_branch. */
3993 tree_try_redirect_by_replacing_jump (edge e, basic_block target)
3995 basic_block src = e->src;
3997 block_stmt_iterator b;
4001 /* Verify that all targets will be TARGET. */
4002 FOR_EACH_EDGE (tmp, ei, src->succs)
4003 if (tmp->dest != target && tmp != e)
4012 stmt = bsi_stmt (b);
4014 if (TREE_CODE (stmt) == COND_EXPR
4015 || TREE_CODE (stmt) == SWITCH_EXPR)
4018 e = ssa_redirect_edge (e, target);
4019 e->flags = EDGE_FALLTHRU;
4027 /* Redirect E to DEST. Return NULL on failure. Otherwise, return the
4028 edge representing the redirected branch. */
4031 tree_redirect_edge_and_branch (edge e, basic_block dest)
4033 basic_block bb = e->src;
4034 block_stmt_iterator bsi;
4038 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
4041 if (e->src != ENTRY_BLOCK_PTR
4042 && (ret = tree_try_redirect_by_replacing_jump (e, dest)))
4045 if (e->dest == dest)
4048 label = tree_block_label (dest);
4050 bsi = bsi_last (bb);
4051 stmt = bsi_end_p (bsi) ? NULL : bsi_stmt (bsi);
4053 switch (stmt ? TREE_CODE (stmt) : ERROR_MARK)
4056 stmt = (e->flags & EDGE_TRUE_VALUE
4057 ? COND_EXPR_THEN (stmt)
4058 : COND_EXPR_ELSE (stmt));
4059 GOTO_DESTINATION (stmt) = label;
4063 /* No non-abnormal edges should lead from a non-simple goto, and
4064 simple ones should be represented implicitly. */
4069 tree vec = SWITCH_LABELS (stmt);
4070 size_t i, n = TREE_VEC_LENGTH (vec);
4072 for (i = 0; i < n; ++i)
4074 tree elt = TREE_VEC_ELT (vec, i);
4075 if (label_to_block (CASE_LABEL (elt)) == e->dest)
4076 CASE_LABEL (elt) = label;
4083 e->flags |= EDGE_FALLTHRU;
4087 /* Otherwise it must be a fallthru edge, and we don't need to
4088 do anything besides redirecting it. */
4089 gcc_assert (e->flags & EDGE_FALLTHRU);
4093 /* Update/insert PHI nodes as necessary. */
4095 /* Now update the edges in the CFG. */
4096 e = ssa_redirect_edge (e, dest);
4102 /* Simple wrapper, as we can always redirect fallthru edges. */
4105 tree_redirect_edge_and_branch_force (edge e, basic_block dest)
4107 e = tree_redirect_edge_and_branch (e, dest);
4114 /* Splits basic block BB after statement STMT (but at least after the
4115 labels). If STMT is NULL, BB is split just after the labels. */
4118 tree_split_block (basic_block bb, void *stmt)
4120 block_stmt_iterator bsi, bsi_tgt;
4126 new_bb = create_empty_bb (bb);
4128 /* Redirect the outgoing edges. */
4129 new_bb->succs = bb->succs;
4131 FOR_EACH_EDGE (e, ei, new_bb->succs)
4134 if (stmt && TREE_CODE ((tree) stmt) == LABEL_EXPR)
4137 /* Move everything from BSI to the new basic block. */
4138 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4140 act = bsi_stmt (bsi);
4141 if (TREE_CODE (act) == LABEL_EXPR)
4154 bsi_tgt = bsi_start (new_bb);
4155 while (!bsi_end_p (bsi))
4157 act = bsi_stmt (bsi);
4159 bsi_insert_after (&bsi_tgt, act, BSI_NEW_STMT);
4166 /* Moves basic block BB after block AFTER. */
4169 tree_move_block_after (basic_block bb, basic_block after)
4171 if (bb->prev_bb == after)
4175 link_block (bb, after);
4181 /* Return true if basic_block can be duplicated. */
4184 tree_can_duplicate_bb_p (basic_block bb ATTRIBUTE_UNUSED)
4189 /* Create a duplicate of the basic block BB. NOTE: This does not
4190 preserve SSA form. */
4193 tree_duplicate_bb (basic_block bb)
4196 block_stmt_iterator bsi, bsi_tgt;
4198 ssa_op_iter op_iter;
4200 new_bb = create_empty_bb (EXIT_BLOCK_PTR->prev_bb);
4202 /* First copy the phi nodes. We do not copy phi node arguments here,
4203 since the edges are not ready yet. Keep the chain of phi nodes in
4204 the same order, so that we can add them later. */
4205 for (phi = phi_nodes (bb); phi; phi = TREE_CHAIN (phi))
4207 mark_for_rewrite (PHI_RESULT (phi));
4208 create_phi_node (PHI_RESULT (phi), new_bb);
4210 set_phi_nodes (new_bb, nreverse (phi_nodes (new_bb)));
4212 bsi_tgt = bsi_start (new_bb);
4213 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4215 tree stmt = bsi_stmt (bsi);
4218 if (TREE_CODE (stmt) == LABEL_EXPR)
4221 /* Record the definitions. */
4222 get_stmt_operands (stmt);
4224 FOR_EACH_SSA_TREE_OPERAND (val, stmt, op_iter, SSA_OP_ALL_DEFS)
4225 mark_for_rewrite (val);
4227 copy = unshare_expr (stmt);
4229 /* Copy also the virtual operands. */
4230 get_stmt_ann (copy);
4231 copy_virtual_operands (copy, stmt);
4233 bsi_insert_after (&bsi_tgt, copy, BSI_NEW_STMT);
4239 /* Basic block BB_COPY was created by code duplication. Add phi node
4240 arguments for edges going out of BB_COPY. The blocks that were
4241 duplicated have rbi->duplicated set to one. */
4244 add_phi_args_after_copy_bb (basic_block bb_copy)
4246 basic_block bb, dest;
4249 tree phi, phi_copy, phi_next, def;
4251 bb = bb_copy->rbi->original;
4253 FOR_EACH_EDGE (e_copy, ei, bb_copy->succs)
4255 if (!phi_nodes (e_copy->dest))
4258 if (e_copy->dest->rbi->duplicated)
4259 dest = e_copy->dest->rbi->original;
4261 dest = e_copy->dest;
4263 e = find_edge (bb, dest);
4266 /* During loop unrolling the target of the latch edge is copied.
4267 In this case we are not looking for edge to dest, but to
4268 duplicated block whose original was dest. */
4269 FOR_EACH_EDGE (e, ei, bb->succs)
4270 if (e->dest->rbi->duplicated
4271 && e->dest->rbi->original == dest)
4274 gcc_assert (e != NULL);
4277 for (phi = phi_nodes (e->dest), phi_copy = phi_nodes (e_copy->dest);
4279 phi = phi_next, phi_copy = TREE_CHAIN (phi_copy))
4281 phi_next = TREE_CHAIN (phi);
4283 gcc_assert (PHI_RESULT (phi) == PHI_RESULT (phi_copy));
4284 def = PHI_ARG_DEF_FROM_EDGE (phi, e);
4285 add_phi_arg (&phi_copy, def, e_copy);
4290 /* Blocks in REGION_COPY array of length N_REGION were created by
4291 duplication of basic blocks. Add phi node arguments for edges
4292 going from these blocks. */
4295 add_phi_args_after_copy (basic_block *region_copy, unsigned n_region)
4299 for (i = 0; i < n_region; i++)
4300 region_copy[i]->rbi->duplicated = 1;
4302 for (i = 0; i < n_region; i++)
4303 add_phi_args_after_copy_bb (region_copy[i]);
4305 for (i = 0; i < n_region; i++)
4306 region_copy[i]->rbi->duplicated = 0;
4309 /* Maps the old ssa name FROM_NAME to TO_NAME. */
4311 struct ssa_name_map_entry
4317 /* Hash function for ssa_name_map_entry. */
4320 ssa_name_map_entry_hash (const void *entry)
4322 const struct ssa_name_map_entry *en = entry;
4323 return SSA_NAME_VERSION (en->from_name);
4326 /* Equality function for ssa_name_map_entry. */
4329 ssa_name_map_entry_eq (const void *in_table, const void *ssa_name)
4331 const struct ssa_name_map_entry *en = in_table;
4333 return en->from_name == ssa_name;
4336 /* Allocate duplicates of ssa names in list DEFINITIONS and store the mapping
4340 allocate_ssa_names (bitmap definitions, htab_t *map)
4343 struct ssa_name_map_entry *entry;
4349 *map = htab_create (10, ssa_name_map_entry_hash,
4350 ssa_name_map_entry_eq, free);
4351 EXECUTE_IF_SET_IN_BITMAP (definitions, 0, ver, bi)
4353 name = ssa_name (ver);
4354 slot = htab_find_slot_with_hash (*map, name, SSA_NAME_VERSION (name),
4360 entry = xmalloc (sizeof (struct ssa_name_map_entry));
4361 entry->from_name = name;
4364 entry->to_name = duplicate_ssa_name (name, SSA_NAME_DEF_STMT (name));
4368 /* Rewrite the definition DEF in statement STMT to new ssa name as specified
4369 by the mapping MAP. */
4372 rewrite_to_new_ssa_names_def (def_operand_p def, tree stmt, htab_t map)
4374 tree name = DEF_FROM_PTR (def);
4375 struct ssa_name_map_entry *entry;
4377 gcc_assert (TREE_CODE (name) == SSA_NAME);
4379 entry = htab_find_with_hash (map, name, SSA_NAME_VERSION (name));
4383 SET_DEF (def, entry->to_name);
4384 SSA_NAME_DEF_STMT (entry->to_name) = stmt;
4387 /* Rewrite the USE to new ssa name as specified by the mapping MAP. */
4390 rewrite_to_new_ssa_names_use (use_operand_p use, htab_t map)
4392 tree name = USE_FROM_PTR (use);
4393 struct ssa_name_map_entry *entry;
4395 if (TREE_CODE (name) != SSA_NAME)
4398 entry = htab_find_with_hash (map, name, SSA_NAME_VERSION (name));
4402 SET_USE (use, entry->to_name);
4405 /* Rewrite the ssa names in basic block BB to new ones as specified by the
4409 rewrite_to_new_ssa_names_bb (basic_block bb, htab_t map)
4415 block_stmt_iterator bsi;
4419 v_may_def_optype v_may_defs;
4420 v_must_def_optype v_must_defs;
4423 FOR_EACH_EDGE (e, ei, bb->preds)
4424 if (e->flags & EDGE_ABNORMAL)
4427 for (phi = phi_nodes (bb); phi; phi = TREE_CHAIN (phi))
4429 rewrite_to_new_ssa_names_def (PHI_RESULT_PTR (phi), phi, map);
4431 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (PHI_RESULT (phi)) = 1;
4434 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4436 stmt = bsi_stmt (bsi);
4437 get_stmt_operands (stmt);
4438 ann = stmt_ann (stmt);
4440 uses = USE_OPS (ann);
4441 for (i = 0; i < NUM_USES (uses); i++)
4442 rewrite_to_new_ssa_names_use (USE_OP_PTR (uses, i), map);
4444 defs = DEF_OPS (ann);
4445 for (i = 0; i < NUM_DEFS (defs); i++)
4446 rewrite_to_new_ssa_names_def (DEF_OP_PTR (defs, i), stmt, map);
4448 vuses = VUSE_OPS (ann);
4449 for (i = 0; i < NUM_VUSES (vuses); i++)
4450 rewrite_to_new_ssa_names_use (VUSE_OP_PTR (vuses, i), map);
4452 v_may_defs = V_MAY_DEF_OPS (ann);
4453 for (i = 0; i < NUM_V_MAY_DEFS (v_may_defs); i++)
4455 rewrite_to_new_ssa_names_use
4456 (V_MAY_DEF_OP_PTR (v_may_defs, i), map);
4457 rewrite_to_new_ssa_names_def
4458 (V_MAY_DEF_RESULT_PTR (v_may_defs, i), stmt, map);
4461 v_must_defs = V_MUST_DEF_OPS (ann);
4462 for (i = 0; i < NUM_V_MUST_DEFS (v_must_defs); i++)
4463 rewrite_to_new_ssa_names_def
4464 (V_MUST_DEF_OP_PTR (v_must_defs, i), stmt, map);
4467 FOR_EACH_EDGE (e, ei, bb->succs)
4468 for (phi = phi_nodes (e->dest); phi; phi = TREE_CHAIN (phi))
4470 rewrite_to_new_ssa_names_use
4471 (PHI_ARG_DEF_PTR_FROM_EDGE (phi, e), map);
4473 if (e->flags & EDGE_ABNORMAL)
4475 tree op = PHI_ARG_DEF_FROM_EDGE (phi, e);
4476 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op) = 1;
4481 /* Rewrite the ssa names in N_REGION blocks REGION to the new ones as specified
4482 by the mapping MAP. */
4485 rewrite_to_new_ssa_names (basic_block *region, unsigned n_region, htab_t map)
4489 for (r = 0; r < n_region; r++)
4490 rewrite_to_new_ssa_names_bb (region[r], map);
4493 /* Duplicates a REGION (set of N_REGION basic blocks) with just a single
4494 important exit edge EXIT. By important we mean that no SSA name defined
4495 inside region is live over the other exit edges of the region. All entry
4496 edges to the region must go to ENTRY->dest. The edge ENTRY is redirected
4497 to the duplicate of the region. SSA form, dominance and loop information
4498 is updated. The new basic blocks are stored to REGION_COPY in the same
4499 order as they had in REGION, provided that REGION_COPY is not NULL.
4500 The function returns false if it is unable to copy the region,
4504 tree_duplicate_sese_region (edge entry, edge exit,
4505 basic_block *region, unsigned n_region,
4506 basic_block *region_copy)
4508 unsigned i, n_doms, ver;
4509 bool free_region_copy = false, copying_header = false;
4510 struct loop *loop = entry->dest->loop_father;
4515 htab_t ssa_name_map = NULL;
4519 if (!can_copy_bbs_p (region, n_region))
4522 /* Some sanity checking. Note that we do not check for all possible
4523 missuses of the functions. I.e. if you ask to copy something weird,
4524 it will work, but the state of structures probably will not be
4527 for (i = 0; i < n_region; i++)
4529 /* We do not handle subloops, i.e. all the blocks must belong to the
4531 if (region[i]->loop_father != loop)
4534 if (region[i] != entry->dest
4535 && region[i] == loop->header)
4541 /* In case the function is used for loop header copying (which is the primary
4542 use), ensure that EXIT and its copy will be new latch and entry edges. */
4543 if (loop->header == entry->dest)
4545 copying_header = true;
4546 loop->copy = loop->outer;
4548 if (!dominated_by_p (CDI_DOMINATORS, loop->latch, exit->src))
4551 for (i = 0; i < n_region; i++)
4552 if (region[i] != exit->src
4553 && dominated_by_p (CDI_DOMINATORS, region[i], exit->src))
4559 region_copy = xmalloc (sizeof (basic_block) * n_region);
4560 free_region_copy = true;
4563 gcc_assert (!any_marked_for_rewrite_p ());
4565 /* Record blocks outside the region that are duplicated by something
4567 doms = xmalloc (sizeof (basic_block) * n_basic_blocks);
4568 n_doms = get_dominated_by_region (CDI_DOMINATORS, region, n_region, doms);
4570 copy_bbs (region, n_region, region_copy, &exit, 1, &exit_copy, loop);
4571 definitions = marked_ssa_names ();
4575 loop->header = exit->dest;
4576 loop->latch = exit->src;
4579 /* Redirect the entry and add the phi node arguments. */
4580 redirected = redirect_edge_and_branch (entry, entry->dest->rbi->copy);
4581 gcc_assert (redirected != NULL);
4582 for (phi = phi_nodes (entry->dest), var = PENDING_STMT (entry);
4584 phi = TREE_CHAIN (phi), var = TREE_CHAIN (var))
4585 add_phi_arg (&phi, TREE_VALUE (var), entry);
4586 PENDING_STMT (entry) = NULL;
4588 /* Concerning updating of dominators: We must recount dominators
4589 for entry block and its copy. Anything that is outside of the region, but
4590 was dominated by something inside needs recounting as well. */
4591 set_immediate_dominator (CDI_DOMINATORS, entry->dest, entry->src);
4592 doms[n_doms++] = entry->dest->rbi->original;
4593 iterate_fix_dominators (CDI_DOMINATORS, doms, n_doms);
4596 /* Add the other phi node arguments. */
4597 add_phi_args_after_copy (region_copy, n_region);
4599 /* Add phi nodes for definitions at exit. TODO -- once we have immediate
4600 uses, it should be possible to emit phi nodes just for definitions that
4601 are used outside region. */
4602 EXECUTE_IF_SET_IN_BITMAP (definitions, 0, ver, bi)
4604 tree name = ssa_name (ver);
4606 phi = create_phi_node (name, exit->dest);
4607 add_phi_arg (&phi, name, exit);
4608 add_phi_arg (&phi, name, exit_copy);
4610 SSA_NAME_DEF_STMT (name) = phi;
4613 /* And create new definitions inside region and its copy. TODO -- once we
4614 have immediate uses, it might be better to leave definitions in region
4615 unchanged, create new ssa names for phi nodes on exit, and rewrite
4616 the uses, to avoid changing the copied region. */
4617 allocate_ssa_names (definitions, &ssa_name_map);
4618 rewrite_to_new_ssa_names (region, n_region, ssa_name_map);
4619 allocate_ssa_names (definitions, &ssa_name_map);
4620 rewrite_to_new_ssa_names (region_copy, n_region, ssa_name_map);
4621 htab_delete (ssa_name_map);
4623 if (free_region_copy)
4626 unmark_all_for_rewrite ();
4627 BITMAP_XFREE (definitions);
4632 /* Dump FUNCTION_DECL FN to file FILE using FLAGS (see TDF_* in tree.h) */
4635 dump_function_to_file (tree fn, FILE *file, int flags)
4637 tree arg, vars, var;
4638 bool ignore_topmost_bind = false, any_var = false;
4642 fprintf (file, "%s (", lang_hooks.decl_printable_name (fn, 2));
4644 arg = DECL_ARGUMENTS (fn);
4647 print_generic_expr (file, arg, dump_flags);
4648 if (TREE_CHAIN (arg))
4649 fprintf (file, ", ");
4650 arg = TREE_CHAIN (arg);
4652 fprintf (file, ")\n");
4654 if (flags & TDF_RAW)
4656 dump_node (fn, TDF_SLIM | flags, file);
4660 /* When GIMPLE is lowered, the variables are no longer available in
4661 BIND_EXPRs, so display them separately. */
4662 if (cfun && cfun->unexpanded_var_list)
4664 ignore_topmost_bind = true;
4666 fprintf (file, "{\n");
4667 for (vars = cfun->unexpanded_var_list; vars; vars = TREE_CHAIN (vars))
4669 var = TREE_VALUE (vars);
4671 print_generic_decl (file, var, flags);
4672 fprintf (file, "\n");
4678 if (basic_block_info)
4680 /* Make a CFG based dump. */
4681 check_bb_profile (ENTRY_BLOCK_PTR, file);
4682 if (!ignore_topmost_bind)
4683 fprintf (file, "{\n");
4685 if (any_var && n_basic_blocks)
4686 fprintf (file, "\n");
4689 dump_generic_bb (file, bb, 2, flags);
4691 fprintf (file, "}\n");
4692 check_bb_profile (EXIT_BLOCK_PTR, file);
4698 /* Make a tree based dump. */
4699 chain = DECL_SAVED_TREE (fn);
4701 if (TREE_CODE (chain) == BIND_EXPR)
4703 if (ignore_topmost_bind)
4705 chain = BIND_EXPR_BODY (chain);
4713 if (!ignore_topmost_bind)
4714 fprintf (file, "{\n");
4719 fprintf (file, "\n");
4721 print_generic_stmt_indented (file, chain, flags, indent);
4722 if (ignore_topmost_bind)
4723 fprintf (file, "}\n");
4726 fprintf (file, "\n\n");
4730 /* Pretty print of the loops intermediate representation. */
4731 static void print_loop (FILE *, struct loop *, int);
4732 static void print_pred_bbs (FILE *, basic_block bb);
4733 static void print_succ_bbs (FILE *, basic_block bb);
4736 /* Print the predecessors indexes of edge E on FILE. */
4739 print_pred_bbs (FILE *file, basic_block bb)
4744 FOR_EACH_EDGE (e, ei, bb->preds)
4745 fprintf (file, "bb_%d", e->src->index);
4749 /* Print the successors indexes of edge E on FILE. */
4752 print_succ_bbs (FILE *file, basic_block bb)
4757 FOR_EACH_EDGE (e, ei, bb->succs)
4758 fprintf (file, "bb_%d", e->src->index);
4762 /* Pretty print LOOP on FILE, indented INDENT spaces. */
4765 print_loop (FILE *file, struct loop *loop, int indent)
4773 s_indent = (char *) alloca ((size_t) indent + 1);
4774 memset ((void *) s_indent, ' ', (size_t) indent);
4775 s_indent[indent] = '\0';
4777 /* Print the loop's header. */
4778 fprintf (file, "%sloop_%d\n", s_indent, loop->num);
4780 /* Print the loop's body. */
4781 fprintf (file, "%s{\n", s_indent);
4783 if (bb->loop_father == loop)
4785 /* Print the basic_block's header. */
4786 fprintf (file, "%s bb_%d (preds = {", s_indent, bb->index);
4787 print_pred_bbs (file, bb);
4788 fprintf (file, "}, succs = {");
4789 print_succ_bbs (file, bb);
4790 fprintf (file, "})\n");
4792 /* Print the basic_block's body. */
4793 fprintf (file, "%s {\n", s_indent);
4794 tree_dump_bb (bb, file, indent + 4);
4795 fprintf (file, "%s }\n", s_indent);
4798 print_loop (file, loop->inner, indent + 2);
4799 fprintf (file, "%s}\n", s_indent);
4800 print_loop (file, loop->next, indent);
4804 /* Follow a CFG edge from the entry point of the program, and on entry
4805 of a loop, pretty print the loop structure on FILE. */
4808 print_loop_ir (FILE *file)
4812 bb = BASIC_BLOCK (0);
4813 if (bb && bb->loop_father)
4814 print_loop (file, bb->loop_father, 0);
4818 /* Debugging loops structure at tree level. */
4821 debug_loop_ir (void)
4823 print_loop_ir (stderr);
4827 /* Return true if BB ends with a call, possibly followed by some
4828 instructions that must stay with the call. Return false,
4832 tree_block_ends_with_call_p (basic_block bb)
4834 block_stmt_iterator bsi = bsi_last (bb);
4835 return get_call_expr_in (bsi_stmt (bsi)) != NULL;
4839 /* Return true if BB ends with a conditional branch. Return false,
4843 tree_block_ends_with_condjump_p (basic_block bb)
4845 tree stmt = tsi_stmt (bsi_last (bb).tsi);
4846 return (TREE_CODE (stmt) == COND_EXPR);
4850 /* Return true if we need to add fake edge to exit at statement T.
4851 Helper function for tree_flow_call_edges_add. */
4854 need_fake_edge_p (tree t)
4858 /* NORETURN and LONGJMP calls already have an edge to exit.
4859 CONST, PURE and ALWAYS_RETURN calls do not need one.
4860 We don't currently check for CONST and PURE here, although
4861 it would be a good idea, because those attributes are
4862 figured out from the RTL in mark_constant_function, and
4863 the counter incrementation code from -fprofile-arcs
4864 leads to different results from -fbranch-probabilities. */
4865 call = get_call_expr_in (t);
4867 && !(call_expr_flags (call) &
4868 (ECF_NORETURN | ECF_LONGJMP | ECF_ALWAYS_RETURN)))
4871 if (TREE_CODE (t) == ASM_EXPR
4872 && (ASM_VOLATILE_P (t) || ASM_INPUT_P (t)))
4879 /* Add fake edges to the function exit for any non constant and non
4880 noreturn calls, volatile inline assembly in the bitmap of blocks
4881 specified by BLOCKS or to the whole CFG if BLOCKS is zero. Return
4882 the number of blocks that were split.
4884 The goal is to expose cases in which entering a basic block does
4885 not imply that all subsequent instructions must be executed. */
4888 tree_flow_call_edges_add (sbitmap blocks)
4891 int blocks_split = 0;
4892 int last_bb = last_basic_block;
4893 bool check_last_block = false;
4895 if (n_basic_blocks == 0)
4899 check_last_block = true;
4901 check_last_block = TEST_BIT (blocks, EXIT_BLOCK_PTR->prev_bb->index);
4903 /* In the last basic block, before epilogue generation, there will be
4904 a fallthru edge to EXIT. Special care is required if the last insn
4905 of the last basic block is a call because make_edge folds duplicate
4906 edges, which would result in the fallthru edge also being marked
4907 fake, which would result in the fallthru edge being removed by
4908 remove_fake_edges, which would result in an invalid CFG.
4910 Moreover, we can't elide the outgoing fake edge, since the block
4911 profiler needs to take this into account in order to solve the minimal
4912 spanning tree in the case that the call doesn't return.
4914 Handle this by adding a dummy instruction in a new last basic block. */
4915 if (check_last_block)
4918 basic_block bb = EXIT_BLOCK_PTR->prev_bb;
4919 block_stmt_iterator bsi = bsi_last (bb);
4921 if (!bsi_end_p (bsi))
4924 if (need_fake_edge_p (t))
4928 FOR_EACH_EDGE (e, ei, bb->succs)
4929 if (e->dest == EXIT_BLOCK_PTR)
4931 bsi_insert_on_edge (e, build_empty_stmt ());
4932 bsi_commit_edge_inserts ((int *)NULL);
4938 /* Now add fake edges to the function exit for any non constant
4939 calls since there is no way that we can determine if they will
4941 for (i = 0; i < last_bb; i++)
4943 basic_block bb = BASIC_BLOCK (i);
4944 block_stmt_iterator bsi;
4945 tree stmt, last_stmt;
4950 if (blocks && !TEST_BIT (blocks, i))
4953 bsi = bsi_last (bb);
4954 if (!bsi_end_p (bsi))
4956 last_stmt = bsi_stmt (bsi);
4959 stmt = bsi_stmt (bsi);
4960 if (need_fake_edge_p (stmt))
4963 /* The handling above of the final block before the
4964 epilogue should be enough to verify that there is
4965 no edge to the exit block in CFG already.
4966 Calling make_edge in such case would cause us to
4967 mark that edge as fake and remove it later. */
4968 #ifdef ENABLE_CHECKING
4969 if (stmt == last_stmt)
4972 FOR_EACH_EDGE (e, ei, bb->succs)
4973 gcc_assert (e->dest != EXIT_BLOCK_PTR);
4977 /* Note that the following may create a new basic block
4978 and renumber the existing basic blocks. */
4979 if (stmt != last_stmt)
4981 e = split_block (bb, stmt);
4985 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
4989 while (!bsi_end_p (bsi));
4994 verify_flow_info ();
4996 return blocks_split;
5000 tree_purge_dead_eh_edges (basic_block bb)
5002 bool changed = false;
5005 tree stmt = last_stmt (bb);
5007 if (stmt && tree_can_throw_internal (stmt))
5010 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
5012 if (e->flags & EDGE_EH)
5014 ssa_remove_edge (e);
5021 /* Removal of dead EH edges might change dominators of not
5022 just immediate successors. E.g. when bb1 is changed so that
5023 it no longer can throw and bb1->bb3 and bb1->bb4 are dead
5024 eh edges purged by this function in:
5036 idom(bb5) must be recomputed. For now just free the dominance
5039 free_dominance_info (CDI_DOMINATORS);
5045 tree_purge_all_dead_eh_edges (bitmap blocks)
5047 bool changed = false;
5051 EXECUTE_IF_SET_IN_BITMAP (blocks, 0, i, bi)
5053 changed |= tree_purge_dead_eh_edges (BASIC_BLOCK (i));
5059 struct cfg_hooks tree_cfg_hooks = {
5061 tree_verify_flow_info,
5062 tree_dump_bb, /* dump_bb */
5063 create_bb, /* create_basic_block */
5064 tree_redirect_edge_and_branch,/* redirect_edge_and_branch */
5065 tree_redirect_edge_and_branch_force,/* redirect_edge_and_branch_force */
5066 remove_bb, /* delete_basic_block */
5067 tree_split_block, /* split_block */
5068 tree_move_block_after, /* move_block_after */
5069 tree_can_merge_blocks_p, /* can_merge_blocks_p */
5070 tree_merge_blocks, /* merge_blocks */
5071 tree_predict_edge, /* predict_edge */
5072 tree_predicted_by_p, /* predicted_by_p */
5073 tree_can_duplicate_bb_p, /* can_duplicate_block_p */
5074 tree_duplicate_bb, /* duplicate_block */
5075 tree_split_edge, /* split_edge */
5076 tree_make_forwarder_block, /* make_forward_block */
5077 NULL, /* tidy_fallthru_edge */
5078 tree_block_ends_with_call_p, /* block_ends_with_call_p */
5079 tree_block_ends_with_condjump_p, /* block_ends_with_condjump_p */
5080 tree_flow_call_edges_add /* flow_call_edges_add */
5084 /* Split all critical edges. */
5087 split_critical_edges (void)
5095 FOR_EACH_EDGE (e, ei, bb->succs)
5096 if (EDGE_CRITICAL_P (e) && !(e->flags & EDGE_ABNORMAL))
5103 struct tree_opt_pass pass_split_crit_edges =
5105 "crited", /* name */
5107 split_critical_edges, /* execute */
5110 0, /* static_pass_number */
5111 TV_TREE_SPLIT_EDGES, /* tv_id */
5112 PROP_cfg, /* properties required */
5113 PROP_no_crit_edges, /* properties_provided */
5114 0, /* properties_destroyed */
5115 0, /* todo_flags_start */
5116 TODO_dump_func, /* todo_flags_finish */
5121 /* Return EXP if it is a valid GIMPLE rvalue, else gimplify it into
5122 a temporary, make sure and register it to be renamed if necessary,
5123 and finally return the temporary. Put the statements to compute
5124 EXP before the current statement in BSI. */
5127 gimplify_val (block_stmt_iterator *bsi, tree type, tree exp)
5129 tree t, new_stmt, orig_stmt;
5131 if (is_gimple_val (exp))
5134 t = make_rename_temp (type, NULL);
5135 new_stmt = build (MODIFY_EXPR, type, t, exp);
5137 orig_stmt = bsi_stmt (*bsi);
5138 SET_EXPR_LOCUS (new_stmt, EXPR_LOCUS (orig_stmt));
5139 TREE_BLOCK (new_stmt) = TREE_BLOCK (orig_stmt);
5141 bsi_insert_before (bsi, new_stmt, BSI_SAME_STMT);
5146 /* Build a ternary operation and gimplify it. Emit code before BSI.
5147 Return the gimple_val holding the result. */
5150 gimplify_build3 (block_stmt_iterator *bsi, enum tree_code code,
5151 tree type, tree a, tree b, tree c)
5155 ret = fold (build3 (code, type, a, b, c));
5158 return gimplify_val (bsi, type, ret);
5161 /* Build a binary operation and gimplify it. Emit code before BSI.
5162 Return the gimple_val holding the result. */
5165 gimplify_build2 (block_stmt_iterator *bsi, enum tree_code code,
5166 tree type, tree a, tree b)
5170 ret = fold (build2 (code, type, a, b));
5173 return gimplify_val (bsi, type, ret);
5176 /* Build a unary operation and gimplify it. Emit code before BSI.
5177 Return the gimple_val holding the result. */
5180 gimplify_build1 (block_stmt_iterator *bsi, enum tree_code code, tree type,
5185 ret = fold (build1 (code, type, a));
5188 return gimplify_val (bsi, type, ret);
5193 /* Emit return warnings. */
5196 execute_warn_function_return (void)
5198 #ifdef USE_MAPPED_LOCATION
5199 source_location location;
5207 if (warn_missing_noreturn
5208 && !TREE_THIS_VOLATILE (cfun->decl)
5209 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) == 0
5210 && !lang_hooks.function.missing_noreturn_ok_p (cfun->decl))
5211 warning ("%Jfunction might be possible candidate for "
5212 "attribute %<noreturn%>",
5215 /* If we have a path to EXIT, then we do return. */
5216 if (TREE_THIS_VOLATILE (cfun->decl)
5217 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) > 0)
5219 #ifdef USE_MAPPED_LOCATION
5220 location = UNKNOWN_LOCATION;
5224 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
5226 last = last_stmt (e->src);
5227 if (TREE_CODE (last) == RETURN_EXPR
5228 #ifdef USE_MAPPED_LOCATION
5229 && (location = EXPR_LOCATION (last)) != UNKNOWN_LOCATION)
5231 && (locus = EXPR_LOCUS (last)) != NULL)
5235 #ifdef USE_MAPPED_LOCATION
5236 if (location == UNKNOWN_LOCATION)
5237 location = cfun->function_end_locus;
5238 warning ("%H%<noreturn%> function does return", &location);
5241 locus = &cfun->function_end_locus;
5242 warning ("%H%<noreturn%> function does return", locus);
5246 /* If we see "return;" in some basic block, then we do reach the end
5247 without returning a value. */
5248 else if (warn_return_type
5249 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) > 0
5250 && !VOID_TYPE_P (TREE_TYPE (TREE_TYPE (cfun->decl))))
5252 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
5254 tree last = last_stmt (e->src);
5255 if (TREE_CODE (last) == RETURN_EXPR
5256 && TREE_OPERAND (last, 0) == NULL)
5258 #ifdef USE_MAPPED_LOCATION
5259 location = EXPR_LOCATION (last);
5260 if (location == UNKNOWN_LOCATION)
5261 location = cfun->function_end_locus;
5262 warning ("%Hcontrol reaches end of non-void function", &location);
5264 locus = EXPR_LOCUS (last);
5266 locus = &cfun->function_end_locus;
5267 warning ("%Hcontrol reaches end of non-void function", locus);
5276 /* Given a basic block B which ends with a conditional and has
5277 precisely two successors, determine which of the edges is taken if
5278 the conditional is true and which is taken if the conditional is
5279 false. Set TRUE_EDGE and FALSE_EDGE appropriately. */
5282 extract_true_false_edges_from_block (basic_block b,
5286 edge e = EDGE_SUCC (b, 0);
5288 if (e->flags & EDGE_TRUE_VALUE)
5291 *false_edge = EDGE_SUCC (b, 1);
5296 *true_edge = EDGE_SUCC (b, 1);
5300 struct tree_opt_pass pass_warn_function_return =
5304 execute_warn_function_return, /* execute */
5307 0, /* static_pass_number */
5309 PROP_cfg, /* properties_required */
5310 0, /* properties_provided */
5311 0, /* properties_destroyed */
5312 0, /* todo_flags_start */
5313 0, /* todo_flags_finish */
5317 #include "gt-tree-cfg.h"