1 /* Control flow functions for trees.
2 Copyright (C) 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
3 Contributed by Diego Novillo <dnovillo@redhat.com>
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 GCC is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to
19 the Free Software Foundation, 59 Temple Place - Suite 330,
20 Boston, MA 02111-1307, USA. */
24 #include "coretypes.h"
29 #include "hard-reg-set.h"
30 #include "basic-block.h"
37 #include "langhooks.h"
38 #include "diagnostic.h"
39 #include "tree-flow.h"
41 #include "tree-dump.h"
42 #include "tree-pass.h"
46 #include "cfglayout.h"
48 /* This file contains functions for building the Control Flow Graph (CFG)
49 for a function tree. */
51 /* Local declarations. */
53 /* Initial capacity for the basic block array. */
54 static const int initial_cfg_capacity = 20;
56 /* Mapping of labels to their associated blocks. This can greatly speed up
57 building of the CFG in code with lots of gotos. */
58 static GTY(()) varray_type label_to_block_map;
63 long num_merged_labels;
66 static struct cfg_stats_d cfg_stats;
68 /* Nonzero if we found a computed goto while building basic blocks. */
69 static bool found_computed_goto;
71 /* Basic blocks and flowgraphs. */
72 static basic_block create_bb (void *, void *, basic_block);
73 static void create_block_annotation (basic_block);
74 static void free_blocks_annotations (void);
75 static void clear_blocks_annotations (void);
76 static void make_blocks (tree);
77 static void factor_computed_gotos (void);
80 static void make_edges (void);
81 static void make_ctrl_stmt_edges (basic_block);
82 static void make_exit_edges (basic_block);
83 static void make_cond_expr_edges (basic_block);
84 static void make_switch_expr_edges (basic_block);
85 static void make_goto_expr_edges (basic_block);
86 static edge tree_redirect_edge_and_branch (edge, basic_block);
87 static edge tree_try_redirect_by_replacing_jump (edge, basic_block);
88 static void split_critical_edges (void);
90 /* Various helpers. */
91 static inline bool stmt_starts_bb_p (tree, tree);
92 static int tree_verify_flow_info (void);
93 static void tree_make_forwarder_block (edge);
94 static bool thread_jumps (void);
95 static bool tree_forwarder_block_p (basic_block);
96 static void bsi_commit_edge_inserts_1 (edge e);
97 static void tree_cfg2vcg (FILE *);
99 /* Flowgraph optimization and cleanup. */
100 static void tree_merge_blocks (basic_block, basic_block);
101 static bool tree_can_merge_blocks_p (basic_block, basic_block);
102 static void remove_bb (basic_block);
103 static bool cleanup_control_flow (void);
104 static bool cleanup_control_expr_graph (basic_block, block_stmt_iterator);
105 static edge find_taken_edge_cond_expr (basic_block, tree);
106 static edge find_taken_edge_switch_expr (basic_block, tree);
107 static tree find_case_label_for_value (tree, tree);
108 static bool phi_alternatives_equal (basic_block, edge, edge);
111 /*---------------------------------------------------------------------------
113 ---------------------------------------------------------------------------*/
115 /* Entry point to the CFG builder for trees. TP points to the list of
116 statements to be added to the flowgraph. */
119 build_tree_cfg (tree *tp)
121 /* Register specific tree functions. */
122 tree_register_cfg_hooks ();
124 /* Initialize rbi_pool. */
127 /* Initialize the basic block array. */
129 profile_status = PROFILE_ABSENT;
131 last_basic_block = 0;
132 VARRAY_BB_INIT (basic_block_info, initial_cfg_capacity, "basic_block_info");
133 memset ((void *) &cfg_stats, 0, sizeof (cfg_stats));
135 /* Build a mapping of labels to their associated blocks. */
136 VARRAY_BB_INIT (label_to_block_map, initial_cfg_capacity,
137 "label to block map");
139 ENTRY_BLOCK_PTR->next_bb = EXIT_BLOCK_PTR;
140 EXIT_BLOCK_PTR->prev_bb = ENTRY_BLOCK_PTR;
142 found_computed_goto = 0;
145 /* Computed gotos are hell to deal with, especially if there are
146 lots of them with a large number of destinations. So we factor
147 them to a common computed goto location before we build the
148 edge list. After we convert back to normal form, we will un-factor
149 the computed gotos since factoring introduces an unwanted jump. */
150 if (found_computed_goto)
151 factor_computed_gotos ();
153 /* Make sure there is always at least one block, even if its empty. */
154 if (n_basic_blocks == 0)
155 create_empty_bb (ENTRY_BLOCK_PTR);
157 create_block_annotation (ENTRY_BLOCK_PTR);
158 create_block_annotation (EXIT_BLOCK_PTR);
160 /* Adjust the size of the array. */
161 VARRAY_GROW (basic_block_info, n_basic_blocks);
163 /* To speed up statement iterator walks, we first purge dead labels. */
164 cleanup_dead_labels ();
166 /* Group case nodes to reduce the number of edges.
167 We do this after cleaning up dead labels because otherwise we miss
168 a lot of obvious case merging opportunities. */
169 group_case_labels ();
171 /* Create the edges of the flowgraph. */
174 /* Debugging dumps. */
176 /* Write the flowgraph to a VCG file. */
178 int local_dump_flags;
179 FILE *dump_file = dump_begin (TDI_vcg, &local_dump_flags);
182 tree_cfg2vcg (dump_file);
183 dump_end (TDI_vcg, dump_file);
187 /* Dump a textual representation of the flowgraph. */
189 dump_tree_cfg (dump_file, dump_flags);
193 execute_build_cfg (void)
195 build_tree_cfg (&DECL_SAVED_TREE (current_function_decl));
198 struct tree_opt_pass pass_build_cfg =
202 execute_build_cfg, /* execute */
205 0, /* static_pass_number */
206 TV_TREE_CFG, /* tv_id */
207 PROP_gimple_leh, /* properties_required */
208 PROP_cfg, /* properties_provided */
209 0, /* properties_destroyed */
210 0, /* todo_flags_start */
211 TODO_verify_stmts, /* todo_flags_finish */
215 /* Search the CFG for any computed gotos. If found, factor them to a
216 common computed goto site. Also record the location of that site so
217 that we can un-factor the gotos after we have converted back to
221 factor_computed_gotos (void)
224 tree factored_label_decl = NULL;
226 tree factored_computed_goto_label = NULL;
227 tree factored_computed_goto = NULL;
229 /* We know there are one or more computed gotos in this function.
230 Examine the last statement in each basic block to see if the block
231 ends with a computed goto. */
235 block_stmt_iterator bsi = bsi_last (bb);
240 last = bsi_stmt (bsi);
242 /* Ignore the computed goto we create when we factor the original
244 if (last == factored_computed_goto)
247 /* If the last statement is a computed goto, factor it. */
248 if (computed_goto_p (last))
252 /* The first time we find a computed goto we need to create
253 the factored goto block and the variable each original
254 computed goto will use for their goto destination. */
255 if (! factored_computed_goto)
257 basic_block new_bb = create_empty_bb (bb);
258 block_stmt_iterator new_bsi = bsi_start (new_bb);
260 /* Create the destination of the factored goto. Each original
261 computed goto will put its desired destination into this
262 variable and jump to the label we create immediately
264 var = create_tmp_var (ptr_type_node, "gotovar");
266 /* Build a label for the new block which will contain the
267 factored computed goto. */
268 factored_label_decl = create_artificial_label ();
269 factored_computed_goto_label
270 = build1 (LABEL_EXPR, void_type_node, factored_label_decl);
271 bsi_insert_after (&new_bsi, factored_computed_goto_label,
274 /* Build our new computed goto. */
275 factored_computed_goto = build1 (GOTO_EXPR, void_type_node, var);
276 bsi_insert_after (&new_bsi, factored_computed_goto,
280 /* Copy the original computed goto's destination into VAR. */
281 assignment = build (MODIFY_EXPR, ptr_type_node,
282 var, GOTO_DESTINATION (last));
283 bsi_insert_before (&bsi, assignment, BSI_SAME_STMT);
285 /* And re-vector the computed goto to the new destination. */
286 GOTO_DESTINATION (last) = factored_label_decl;
292 /* Create annotations for a single basic block. */
295 create_block_annotation (basic_block bb)
297 /* Verify that the tree_annotations field is clear. */
298 gcc_assert (!bb->tree_annotations);
299 bb->tree_annotations = ggc_alloc_cleared (sizeof (struct bb_ann_d));
303 /* Free the annotations for all the basic blocks. */
305 static void free_blocks_annotations (void)
307 clear_blocks_annotations ();
311 /* Clear the annotations for all the basic blocks. */
314 clear_blocks_annotations (void)
318 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb)
319 bb->tree_annotations = NULL;
323 /* Build a flowgraph for the statement_list STMT_LIST. */
326 make_blocks (tree stmt_list)
328 tree_stmt_iterator i = tsi_start (stmt_list);
330 bool start_new_block = true;
331 bool first_stmt_of_list = true;
332 basic_block bb = ENTRY_BLOCK_PTR;
334 while (!tsi_end_p (i))
341 /* If the statement starts a new basic block or if we have determined
342 in a previous pass that we need to create a new block for STMT, do
344 if (start_new_block || stmt_starts_bb_p (stmt, prev_stmt))
346 if (!first_stmt_of_list)
347 stmt_list = tsi_split_statement_list_before (&i);
348 bb = create_basic_block (stmt_list, NULL, bb);
349 start_new_block = false;
352 /* Now add STMT to BB and create the subgraphs for special statement
354 set_bb_for_stmt (stmt, bb);
356 if (computed_goto_p (stmt))
357 found_computed_goto = true;
359 /* If STMT is a basic block terminator, set START_NEW_BLOCK for the
361 if (stmt_ends_bb_p (stmt))
362 start_new_block = true;
365 first_stmt_of_list = false;
370 /* Create and return a new empty basic block after bb AFTER. */
373 create_bb (void *h, void *e, basic_block after)
379 /* Create and initialize a new basic block. */
381 memset (bb, 0, sizeof (*bb));
383 bb->index = last_basic_block;
385 bb->stmt_list = h ? h : alloc_stmt_list ();
387 /* Add the new block to the linked list of blocks. */
388 link_block (bb, after);
390 /* Grow the basic block array if needed. */
391 if ((size_t) last_basic_block == VARRAY_SIZE (basic_block_info))
393 size_t new_size = last_basic_block + (last_basic_block + 3) / 4;
394 VARRAY_GROW (basic_block_info, new_size);
397 /* Add the newly created block to the array. */
398 BASIC_BLOCK (last_basic_block) = bb;
400 create_block_annotation (bb);
405 initialize_bb_rbi (bb);
410 /*---------------------------------------------------------------------------
412 ---------------------------------------------------------------------------*/
414 /* Join all the blocks in the flowgraph. */
421 /* Create an edge from entry to the first block with executable
423 make_edge (ENTRY_BLOCK_PTR, BASIC_BLOCK (0), EDGE_FALLTHRU);
425 /* Traverse basic block array placing edges. */
428 tree first = first_stmt (bb);
429 tree last = last_stmt (bb);
433 /* Edges for statements that always alter flow control. */
434 if (is_ctrl_stmt (last))
435 make_ctrl_stmt_edges (bb);
437 /* Edges for statements that sometimes alter flow control. */
438 if (is_ctrl_altering_stmt (last))
439 make_exit_edges (bb);
442 /* Finally, if no edges were created above, this is a regular
443 basic block that only needs a fallthru edge. */
444 if (EDGE_COUNT (bb->succs) == 0)
445 make_edge (bb, bb->next_bb, EDGE_FALLTHRU);
448 /* We do not care about fake edges, so remove any that the CFG
449 builder inserted for completeness. */
450 remove_fake_exit_edges ();
452 /* Clean up the graph and warn for unreachable code. */
457 /* Create edges for control statement at basic block BB. */
460 make_ctrl_stmt_edges (basic_block bb)
462 tree last = last_stmt (bb);
465 switch (TREE_CODE (last))
468 make_goto_expr_edges (bb);
472 make_edge (bb, EXIT_BLOCK_PTR, 0);
476 make_cond_expr_edges (bb);
480 make_switch_expr_edges (bb);
484 make_eh_edges (last);
485 /* Yet another NORETURN hack. */
486 if (EDGE_COUNT (bb->succs) == 0)
487 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
496 /* Create exit edges for statements in block BB that alter the flow of
497 control. Statements that alter the control flow are 'goto', 'return'
498 and calls to non-returning functions. */
501 make_exit_edges (basic_block bb)
503 tree last = last_stmt (bb), op;
506 switch (TREE_CODE (last))
509 /* If this function receives a nonlocal goto, then we need to
510 make edges from this call site to all the nonlocal goto
512 if (TREE_SIDE_EFFECTS (last)
513 && current_function_has_nonlocal_label)
514 make_goto_expr_edges (bb);
516 /* If this statement has reachable exception handlers, then
517 create abnormal edges to them. */
518 make_eh_edges (last);
520 /* Some calls are known not to return. For such calls we create
523 We really need to revamp how we build edges so that it's not
524 such a bloody pain to avoid creating edges for this case since
525 all we do is remove these edges when we're done building the
527 if (call_expr_flags (last) & (ECF_NORETURN | ECF_LONGJMP))
529 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
533 /* Don't forget the fall-thru edge. */
534 make_edge (bb, bb->next_bb, EDGE_FALLTHRU);
538 /* A MODIFY_EXPR may have a CALL_EXPR on its RHS and the CALL_EXPR
539 may have an abnormal edge. Search the RHS for this case and
540 create any required edges. */
541 op = get_call_expr_in (last);
542 if (op && TREE_SIDE_EFFECTS (op)
543 && current_function_has_nonlocal_label)
544 make_goto_expr_edges (bb);
546 make_eh_edges (last);
547 make_edge (bb, bb->next_bb, EDGE_FALLTHRU);
556 /* Create the edges for a COND_EXPR starting at block BB.
557 At this point, both clauses must contain only simple gotos. */
560 make_cond_expr_edges (basic_block bb)
562 tree entry = last_stmt (bb);
563 basic_block then_bb, else_bb;
564 tree then_label, else_label;
567 gcc_assert (TREE_CODE (entry) == COND_EXPR);
569 /* Entry basic blocks for each component. */
570 then_label = GOTO_DESTINATION (COND_EXPR_THEN (entry));
571 else_label = GOTO_DESTINATION (COND_EXPR_ELSE (entry));
572 then_bb = label_to_block (then_label);
573 else_bb = label_to_block (else_label);
575 make_edge (bb, then_bb, EDGE_TRUE_VALUE);
576 make_edge (bb, else_bb, EDGE_FALSE_VALUE);
580 /* Create the edges for a SWITCH_EXPR starting at block BB.
581 At this point, the switch body has been lowered and the
582 SWITCH_LABELS filled in, so this is in effect a multi-way branch. */
585 make_switch_expr_edges (basic_block bb)
587 tree entry = last_stmt (bb);
591 vec = SWITCH_LABELS (entry);
592 n = TREE_VEC_LENGTH (vec);
594 for (i = 0; i < n; ++i)
596 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
597 basic_block label_bb = label_to_block (lab);
598 make_edge (bb, label_bb, 0);
603 /* Return the basic block holding label DEST. */
606 label_to_block (tree dest)
608 int uid = LABEL_DECL_UID (dest);
610 /* We would die hard when faced by undefined label. Emit label to
611 very first basic block. This will hopefully make even the dataflow
612 and undefined variable warnings quite right. */
613 if ((errorcount || sorrycount) && uid < 0)
615 block_stmt_iterator bsi = bsi_start (BASIC_BLOCK (0));
618 stmt = build1 (LABEL_EXPR, void_type_node, dest);
619 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
620 uid = LABEL_DECL_UID (dest);
622 return VARRAY_BB (label_to_block_map, uid);
626 /* Create edges for a goto statement at block BB. */
629 make_goto_expr_edges (basic_block bb)
632 basic_block target_bb;
634 block_stmt_iterator last = bsi_last (bb);
636 goto_t = bsi_stmt (last);
638 /* If the last statement is not a GOTO (i.e., it is a RETURN_EXPR,
639 CALL_EXPR or MODIFY_EXPR), then the edge is an abnormal edge resulting
640 from a nonlocal goto. */
641 if (TREE_CODE (goto_t) != GOTO_EXPR)
643 dest = error_mark_node;
648 dest = GOTO_DESTINATION (goto_t);
651 /* A GOTO to a local label creates normal edges. */
652 if (simple_goto_p (goto_t))
654 edge e = make_edge (bb, label_to_block (dest), EDGE_FALLTHRU);
655 #ifdef USE_MAPPED_LOCATION
656 e->goto_locus = EXPR_LOCATION (goto_t);
658 e->goto_locus = EXPR_LOCUS (goto_t);
664 /* Nothing more to do for nonlocal gotos. */
665 if (TREE_CODE (dest) == LABEL_DECL)
668 /* Computed gotos remain. */
671 /* Look for the block starting with the destination label. In the
672 case of a computed goto, make an edge to any label block we find
674 FOR_EACH_BB (target_bb)
676 block_stmt_iterator bsi;
678 for (bsi = bsi_start (target_bb); !bsi_end_p (bsi); bsi_next (&bsi))
680 tree target = bsi_stmt (bsi);
682 if (TREE_CODE (target) != LABEL_EXPR)
686 /* Computed GOTOs. Make an edge to every label block that has
687 been marked as a potential target for a computed goto. */
688 (FORCED_LABEL (LABEL_EXPR_LABEL (target)) && for_call == 0)
689 /* Nonlocal GOTO target. Make an edge to every label block
690 that has been marked as a potential target for a nonlocal
692 || (DECL_NONLOCAL (LABEL_EXPR_LABEL (target)) && for_call == 1))
694 make_edge (bb, target_bb, EDGE_ABNORMAL);
700 /* Degenerate case of computed goto with no labels. */
701 if (!for_call && EDGE_COUNT (bb->succs) == 0)
702 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
706 /*---------------------------------------------------------------------------
708 ---------------------------------------------------------------------------*/
710 /* Remove unreachable blocks and other miscellaneous clean up work. */
713 cleanup_tree_cfg (void)
715 bool something_changed = true;
718 timevar_push (TV_TREE_CLEANUP_CFG);
720 /* These three transformations can cascade, so we iterate on them until
722 while (something_changed)
724 something_changed = cleanup_control_flow ();
725 something_changed |= delete_unreachable_blocks ();
726 something_changed |= thread_jumps ();
727 retval |= something_changed;
730 /* Merging the blocks creates no new opportunities for the other
731 optimizations, so do it here. */
736 #ifdef ENABLE_CHECKING
739 timevar_pop (TV_TREE_CLEANUP_CFG);
744 /* Cleanup useless labels in basic blocks. This is something we wish
745 to do early because it allows us to group case labels before creating
746 the edges for the CFG, and it speeds up block statement iterators in
748 We only run this pass once, running it more than once is probably not
751 /* A map from basic block index to the leading label of that block. */
752 static tree *label_for_bb;
754 /* Callback for for_each_eh_region. Helper for cleanup_dead_labels. */
756 update_eh_label (struct eh_region *region)
758 tree old_label = get_eh_region_tree_label (region);
762 basic_block bb = label_to_block (old_label);
764 /* ??? After optimizing, there may be EH regions with labels
765 that have already been removed from the function body, so
766 there is no basic block for them. */
770 new_label = label_for_bb[bb->index];
771 set_eh_region_tree_label (region, new_label);
775 /* Given LABEL return the first label in the same basic block. */
777 main_block_label (tree label)
779 basic_block bb = label_to_block (label);
781 /* label_to_block possibly inserted undefined label into the chain. */
782 if (!label_for_bb[bb->index])
783 label_for_bb[bb->index] = label;
784 return label_for_bb[bb->index];
787 /* Cleanup redundant labels. This is a three-steo process:
788 1) Find the leading label for each block.
789 2) Redirect all references to labels to the leading labels.
790 3) Cleanup all useless labels. */
793 cleanup_dead_labels (void)
796 label_for_bb = xcalloc (last_basic_block, sizeof (tree));
798 /* Find a suitable label for each block. We use the first user-defined
799 label is there is one, or otherwise just the first label we see. */
802 block_stmt_iterator i;
804 for (i = bsi_start (bb); !bsi_end_p (i); bsi_next (&i))
806 tree label, stmt = bsi_stmt (i);
808 if (TREE_CODE (stmt) != LABEL_EXPR)
811 label = LABEL_EXPR_LABEL (stmt);
813 /* If we have not yet seen a label for the current block,
814 remember this one and see if there are more labels. */
815 if (! label_for_bb[bb->index])
817 label_for_bb[bb->index] = label;
821 /* If we did see a label for the current block already, but it
822 is an artificially created label, replace it if the current
823 label is a user defined label. */
824 if (! DECL_ARTIFICIAL (label)
825 && DECL_ARTIFICIAL (label_for_bb[bb->index]))
827 label_for_bb[bb->index] = label;
833 /* Now redirect all jumps/branches to the selected label.
834 First do so for each block ending in a control statement. */
837 tree stmt = last_stmt (bb);
841 switch (TREE_CODE (stmt))
845 tree true_branch, false_branch;
847 true_branch = COND_EXPR_THEN (stmt);
848 false_branch = COND_EXPR_ELSE (stmt);
850 GOTO_DESTINATION (true_branch)
851 = main_block_label (GOTO_DESTINATION (true_branch));
852 GOTO_DESTINATION (false_branch)
853 = main_block_label (GOTO_DESTINATION (false_branch));
861 tree vec = SWITCH_LABELS (stmt);
862 size_t n = TREE_VEC_LENGTH (vec);
864 /* Replace all destination labels. */
865 for (i = 0; i < n; ++i)
866 CASE_LABEL (TREE_VEC_ELT (vec, i))
867 = main_block_label (CASE_LABEL (TREE_VEC_ELT (vec, i)));
872 /* We have to handle GOTO_EXPRs until they're removed, and we don't
873 remove them until after we've created the CFG edges. */
875 if (! computed_goto_p (stmt))
877 GOTO_DESTINATION (stmt)
878 = main_block_label (GOTO_DESTINATION (stmt));
887 for_each_eh_region (update_eh_label);
889 /* Finally, purge dead labels. All user-defined labels and labels that
890 can be the target of non-local gotos are preserved. */
893 block_stmt_iterator i;
894 tree label_for_this_bb = label_for_bb[bb->index];
896 if (! label_for_this_bb)
899 for (i = bsi_start (bb); !bsi_end_p (i); )
901 tree label, stmt = bsi_stmt (i);
903 if (TREE_CODE (stmt) != LABEL_EXPR)
906 label = LABEL_EXPR_LABEL (stmt);
908 if (label == label_for_this_bb
909 || ! DECL_ARTIFICIAL (label)
910 || DECL_NONLOCAL (label))
920 /* Look for blocks ending in a multiway branch (a SWITCH_EXPR in GIMPLE),
921 and scan the sorted vector of cases. Combine the ones jumping to the
923 Eg. three separate entries 1: 2: 3: become one entry 1..3: */
926 group_case_labels (void)
932 tree stmt = last_stmt (bb);
933 if (stmt && TREE_CODE (stmt) == SWITCH_EXPR)
935 tree labels = SWITCH_LABELS (stmt);
936 int old_size = TREE_VEC_LENGTH (labels);
937 int i, j, new_size = old_size;
938 tree default_label = TREE_VEC_ELT (labels, old_size - 1);
940 /* Look for possible opportunities to merge cases.
941 Ignore the last element of the label vector because it
942 must be the default case. */
944 while (i < old_size - 2)
946 tree base_case, base_label, base_high, type;
947 base_case = TREE_VEC_ELT (labels, i);
949 gcc_assert (base_case);
950 base_label = CASE_LABEL (base_case);
952 /* Discard cases that have the same destination as the
954 if (base_label == default_label)
956 TREE_VEC_ELT (labels, i) = NULL_TREE;
961 type = TREE_TYPE (CASE_LOW (base_case));
962 base_high = CASE_HIGH (base_case) ?
963 CASE_HIGH (base_case) : CASE_LOW (base_case);
965 /* Try to merge case labels. Break out when we reach the end
966 of the label vector or when we cannot merge the next case
967 label with the current one. */
968 while (i < old_size - 2)
970 tree merge_case = TREE_VEC_ELT (labels, ++i);
971 tree merge_label = CASE_LABEL (merge_case);
972 tree t = int_const_binop (PLUS_EXPR, base_high,
973 integer_one_node, 1);
975 /* Merge the cases if they jump to the same place,
976 and their ranges are consecutive. */
977 if (merge_label == base_label
978 && tree_int_cst_equal (CASE_LOW (merge_case), t))
980 base_high = CASE_HIGH (merge_case) ?
981 CASE_HIGH (merge_case) : CASE_LOW (merge_case);
982 CASE_HIGH (base_case) = base_high;
983 TREE_VEC_ELT (labels, i) = NULL_TREE;
991 /* Compress the case labels in the label vector, and adjust the
992 length of the vector. */
993 for (i = 0, j = 0; i < new_size; i++)
995 while (! TREE_VEC_ELT (labels, j))
997 TREE_VEC_ELT (labels, i) = TREE_VEC_ELT (labels, j++);
999 TREE_VEC_LENGTH (labels) = new_size;
1004 /* Checks whether we can merge block B into block A. */
1007 tree_can_merge_blocks_p (basic_block a, basic_block b)
1010 block_stmt_iterator bsi;
1012 if (EDGE_COUNT (a->succs) != 1)
1015 if (EDGE_SUCC (a, 0)->flags & EDGE_ABNORMAL)
1018 if (EDGE_SUCC (a, 0)->dest != b)
1021 if (b == EXIT_BLOCK_PTR)
1024 if (EDGE_COUNT (b->preds) > 1)
1027 /* If A ends by a statement causing exceptions or something similar, we
1028 cannot merge the blocks. */
1029 stmt = last_stmt (a);
1030 if (stmt && stmt_ends_bb_p (stmt))
1033 /* Do not allow a block with only a non-local label to be merged. */
1034 if (stmt && TREE_CODE (stmt) == LABEL_EXPR
1035 && DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)))
1038 /* There may be no phi nodes at the start of b. Most of these degenerate
1039 phi nodes should be cleaned up by kill_redundant_phi_nodes. */
1043 /* Do not remove user labels. */
1044 for (bsi = bsi_start (b); !bsi_end_p (bsi); bsi_next (&bsi))
1046 stmt = bsi_stmt (bsi);
1047 if (TREE_CODE (stmt) != LABEL_EXPR)
1049 if (!DECL_ARTIFICIAL (LABEL_EXPR_LABEL (stmt)))
1057 /* Merge block B into block A. */
1060 tree_merge_blocks (basic_block a, basic_block b)
1062 block_stmt_iterator bsi;
1063 tree_stmt_iterator last;
1066 fprintf (dump_file, "Merging blocks %d and %d\n", a->index, b->index);
1068 /* Ensure that B follows A. */
1069 move_block_after (b, a);
1071 gcc_assert (EDGE_SUCC (a, 0)->flags & EDGE_FALLTHRU);
1072 gcc_assert (!last_stmt (a) || !stmt_ends_bb_p (last_stmt (a)));
1074 /* Remove labels from B and set bb_for_stmt to A for other statements. */
1075 for (bsi = bsi_start (b); !bsi_end_p (bsi);)
1077 if (TREE_CODE (bsi_stmt (bsi)) == LABEL_EXPR)
1081 set_bb_for_stmt (bsi_stmt (bsi), a);
1086 /* Merge the chains. */
1087 last = tsi_last (a->stmt_list);
1088 tsi_link_after (&last, b->stmt_list, TSI_NEW_STMT);
1089 b->stmt_list = NULL;
1093 /* Walk the function tree removing unnecessary statements.
1095 * Empty statement nodes are removed
1097 * Unnecessary TRY_FINALLY and TRY_CATCH blocks are removed
1099 * Unnecessary COND_EXPRs are removed
1101 * Some unnecessary BIND_EXPRs are removed
1103 Clearly more work could be done. The trick is doing the analysis
1104 and removal fast enough to be a net improvement in compile times.
1106 Note that when we remove a control structure such as a COND_EXPR
1107 BIND_EXPR, or TRY block, we will need to repeat this optimization pass
1108 to ensure we eliminate all the useless code. */
1119 static void remove_useless_stmts_1 (tree *, struct rus_data *);
1122 remove_useless_stmts_warn_notreached (tree stmt)
1124 if (EXPR_HAS_LOCATION (stmt))
1126 location_t loc = EXPR_LOCATION (stmt);
1127 warning ("%Hwill never be executed", &loc);
1131 switch (TREE_CODE (stmt))
1133 case STATEMENT_LIST:
1135 tree_stmt_iterator i;
1136 for (i = tsi_start (stmt); !tsi_end_p (i); tsi_next (&i))
1137 if (remove_useless_stmts_warn_notreached (tsi_stmt (i)))
1143 if (remove_useless_stmts_warn_notreached (COND_EXPR_COND (stmt)))
1145 if (remove_useless_stmts_warn_notreached (COND_EXPR_THEN (stmt)))
1147 if (remove_useless_stmts_warn_notreached (COND_EXPR_ELSE (stmt)))
1151 case TRY_FINALLY_EXPR:
1152 case TRY_CATCH_EXPR:
1153 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt, 0)))
1155 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt, 1)))
1160 return remove_useless_stmts_warn_notreached (CATCH_BODY (stmt));
1161 case EH_FILTER_EXPR:
1162 return remove_useless_stmts_warn_notreached (EH_FILTER_FAILURE (stmt));
1164 return remove_useless_stmts_warn_notreached (BIND_EXPR_BLOCK (stmt));
1167 /* Not a live container. */
1175 remove_useless_stmts_cond (tree *stmt_p, struct rus_data *data)
1177 tree then_clause, else_clause, cond;
1178 bool save_has_label, then_has_label, else_has_label;
1180 save_has_label = data->has_label;
1181 data->has_label = false;
1182 data->last_goto = NULL;
1184 remove_useless_stmts_1 (&COND_EXPR_THEN (*stmt_p), data);
1186 then_has_label = data->has_label;
1187 data->has_label = false;
1188 data->last_goto = NULL;
1190 remove_useless_stmts_1 (&COND_EXPR_ELSE (*stmt_p), data);
1192 else_has_label = data->has_label;
1193 data->has_label = save_has_label | then_has_label | else_has_label;
1196 then_clause = COND_EXPR_THEN (*stmt_p);
1197 else_clause = COND_EXPR_ELSE (*stmt_p);
1198 cond = COND_EXPR_COND (*stmt_p);
1200 /* If neither arm does anything at all, we can remove the whole IF. */
1201 if (!TREE_SIDE_EFFECTS (then_clause) && !TREE_SIDE_EFFECTS (else_clause))
1203 *stmt_p = build_empty_stmt ();
1204 data->repeat = true;
1207 /* If there are no reachable statements in an arm, then we can
1208 zap the entire conditional. */
1209 else if (integer_nonzerop (cond) && !else_has_label)
1211 if (warn_notreached)
1212 remove_useless_stmts_warn_notreached (else_clause);
1213 *stmt_p = then_clause;
1214 data->repeat = true;
1216 else if (integer_zerop (cond) && !then_has_label)
1218 if (warn_notreached)
1219 remove_useless_stmts_warn_notreached (then_clause);
1220 *stmt_p = else_clause;
1221 data->repeat = true;
1224 /* Check a couple of simple things on then/else with single stmts. */
1227 tree then_stmt = expr_only (then_clause);
1228 tree else_stmt = expr_only (else_clause);
1230 /* Notice branches to a common destination. */
1231 if (then_stmt && else_stmt
1232 && TREE_CODE (then_stmt) == GOTO_EXPR
1233 && TREE_CODE (else_stmt) == GOTO_EXPR
1234 && (GOTO_DESTINATION (then_stmt) == GOTO_DESTINATION (else_stmt)))
1236 *stmt_p = then_stmt;
1237 data->repeat = true;
1240 /* If the THEN/ELSE clause merely assigns a value to a variable or
1241 parameter which is already known to contain that value, then
1242 remove the useless THEN/ELSE clause. */
1243 else if (TREE_CODE (cond) == VAR_DECL || TREE_CODE (cond) == PARM_DECL)
1246 && TREE_CODE (else_stmt) == MODIFY_EXPR
1247 && TREE_OPERAND (else_stmt, 0) == cond
1248 && integer_zerop (TREE_OPERAND (else_stmt, 1)))
1249 COND_EXPR_ELSE (*stmt_p) = alloc_stmt_list ();
1251 else if ((TREE_CODE (cond) == EQ_EXPR || TREE_CODE (cond) == NE_EXPR)
1252 && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL
1253 || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL)
1254 && TREE_CONSTANT (TREE_OPERAND (cond, 1)))
1256 tree stmt = (TREE_CODE (cond) == EQ_EXPR
1257 ? then_stmt : else_stmt);
1258 tree *location = (TREE_CODE (cond) == EQ_EXPR
1259 ? &COND_EXPR_THEN (*stmt_p)
1260 : &COND_EXPR_ELSE (*stmt_p));
1263 && TREE_CODE (stmt) == MODIFY_EXPR
1264 && TREE_OPERAND (stmt, 0) == TREE_OPERAND (cond, 0)
1265 && TREE_OPERAND (stmt, 1) == TREE_OPERAND (cond, 1))
1266 *location = alloc_stmt_list ();
1270 /* Protect GOTOs in the arm of COND_EXPRs from being removed. They
1271 would be re-introduced during lowering. */
1272 data->last_goto = NULL;
1277 remove_useless_stmts_tf (tree *stmt_p, struct rus_data *data)
1279 bool save_may_branch, save_may_throw;
1280 bool this_may_branch, this_may_throw;
1282 /* Collect may_branch and may_throw information for the body only. */
1283 save_may_branch = data->may_branch;
1284 save_may_throw = data->may_throw;
1285 data->may_branch = false;
1286 data->may_throw = false;
1287 data->last_goto = NULL;
1289 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 0), data);
1291 this_may_branch = data->may_branch;
1292 this_may_throw = data->may_throw;
1293 data->may_branch |= save_may_branch;
1294 data->may_throw |= save_may_throw;
1295 data->last_goto = NULL;
1297 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 1), data);
1299 /* If the body is empty, then we can emit the FINALLY block without
1300 the enclosing TRY_FINALLY_EXPR. */
1301 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 0)))
1303 *stmt_p = TREE_OPERAND (*stmt_p, 1);
1304 data->repeat = true;
1307 /* If the handler is empty, then we can emit the TRY block without
1308 the enclosing TRY_FINALLY_EXPR. */
1309 else if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 1)))
1311 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1312 data->repeat = true;
1315 /* If the body neither throws, nor branches, then we can safely
1316 string the TRY and FINALLY blocks together. */
1317 else if (!this_may_branch && !this_may_throw)
1319 tree stmt = *stmt_p;
1320 *stmt_p = TREE_OPERAND (stmt, 0);
1321 append_to_statement_list (TREE_OPERAND (stmt, 1), stmt_p);
1322 data->repeat = true;
1328 remove_useless_stmts_tc (tree *stmt_p, struct rus_data *data)
1330 bool save_may_throw, this_may_throw;
1331 tree_stmt_iterator i;
1334 /* Collect may_throw information for the body only. */
1335 save_may_throw = data->may_throw;
1336 data->may_throw = false;
1337 data->last_goto = NULL;
1339 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 0), data);
1341 this_may_throw = data->may_throw;
1342 data->may_throw = save_may_throw;
1344 /* If the body cannot throw, then we can drop the entire TRY_CATCH_EXPR. */
1345 if (!this_may_throw)
1347 if (warn_notreached)
1348 remove_useless_stmts_warn_notreached (TREE_OPERAND (*stmt_p, 1));
1349 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1350 data->repeat = true;
1354 /* Process the catch clause specially. We may be able to tell that
1355 no exceptions propagate past this point. */
1357 this_may_throw = true;
1358 i = tsi_start (TREE_OPERAND (*stmt_p, 1));
1359 stmt = tsi_stmt (i);
1360 data->last_goto = NULL;
1362 switch (TREE_CODE (stmt))
1365 for (; !tsi_end_p (i); tsi_next (&i))
1367 stmt = tsi_stmt (i);
1368 /* If we catch all exceptions, then the body does not
1369 propagate exceptions past this point. */
1370 if (CATCH_TYPES (stmt) == NULL)
1371 this_may_throw = false;
1372 data->last_goto = NULL;
1373 remove_useless_stmts_1 (&CATCH_BODY (stmt), data);
1377 case EH_FILTER_EXPR:
1378 if (EH_FILTER_MUST_NOT_THROW (stmt))
1379 this_may_throw = false;
1380 else if (EH_FILTER_TYPES (stmt) == NULL)
1381 this_may_throw = false;
1382 remove_useless_stmts_1 (&EH_FILTER_FAILURE (stmt), data);
1386 /* Otherwise this is a cleanup. */
1387 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 1), data);
1389 /* If the cleanup is empty, then we can emit the TRY block without
1390 the enclosing TRY_CATCH_EXPR. */
1391 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 1)))
1393 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1394 data->repeat = true;
1398 data->may_throw |= this_may_throw;
1403 remove_useless_stmts_bind (tree *stmt_p, struct rus_data *data)
1407 /* First remove anything underneath the BIND_EXPR. */
1408 remove_useless_stmts_1 (&BIND_EXPR_BODY (*stmt_p), data);
1410 /* If the BIND_EXPR has no variables, then we can pull everything
1411 up one level and remove the BIND_EXPR, unless this is the toplevel
1412 BIND_EXPR for the current function or an inlined function.
1414 When this situation occurs we will want to apply this
1415 optimization again. */
1416 block = BIND_EXPR_BLOCK (*stmt_p);
1417 if (BIND_EXPR_VARS (*stmt_p) == NULL_TREE
1418 && *stmt_p != DECL_SAVED_TREE (current_function_decl)
1420 || ! BLOCK_ABSTRACT_ORIGIN (block)
1421 || (TREE_CODE (BLOCK_ABSTRACT_ORIGIN (block))
1424 *stmt_p = BIND_EXPR_BODY (*stmt_p);
1425 data->repeat = true;
1431 remove_useless_stmts_goto (tree *stmt_p, struct rus_data *data)
1433 tree dest = GOTO_DESTINATION (*stmt_p);
1435 data->may_branch = true;
1436 data->last_goto = NULL;
1438 /* Record the last goto expr, so that we can delete it if unnecessary. */
1439 if (TREE_CODE (dest) == LABEL_DECL)
1440 data->last_goto = stmt_p;
1445 remove_useless_stmts_label (tree *stmt_p, struct rus_data *data)
1447 tree label = LABEL_EXPR_LABEL (*stmt_p);
1449 data->has_label = true;
1451 /* We do want to jump across non-local label receiver code. */
1452 if (DECL_NONLOCAL (label))
1453 data->last_goto = NULL;
1455 else if (data->last_goto && GOTO_DESTINATION (*data->last_goto) == label)
1457 *data->last_goto = build_empty_stmt ();
1458 data->repeat = true;
1461 /* ??? Add something here to delete unused labels. */
1465 /* If the function is "const" or "pure", then clear TREE_SIDE_EFFECTS on its
1466 decl. This allows us to eliminate redundant or useless
1467 calls to "const" functions.
1469 Gimplifier already does the same operation, but we may notice functions
1470 being const and pure once their calls has been gimplified, so we need
1471 to update the flag. */
1474 update_call_expr_flags (tree call)
1476 tree decl = get_callee_fndecl (call);
1479 if (call_expr_flags (call) & (ECF_CONST | ECF_PURE))
1480 TREE_SIDE_EFFECTS (call) = 0;
1481 if (TREE_NOTHROW (decl))
1482 TREE_NOTHROW (call) = 1;
1486 /* T is CALL_EXPR. Set current_function_calls_* flags. */
1489 notice_special_calls (tree t)
1491 int flags = call_expr_flags (t);
1493 if (flags & ECF_MAY_BE_ALLOCA)
1494 current_function_calls_alloca = true;
1495 if (flags & ECF_RETURNS_TWICE)
1496 current_function_calls_setjmp = true;
1500 /* Clear flags set by notice_special_calls. Used by dead code removal
1501 to update the flags. */
1504 clear_special_calls (void)
1506 current_function_calls_alloca = false;
1507 current_function_calls_setjmp = false;
1512 remove_useless_stmts_1 (tree *tp, struct rus_data *data)
1516 switch (TREE_CODE (t))
1519 remove_useless_stmts_cond (tp, data);
1522 case TRY_FINALLY_EXPR:
1523 remove_useless_stmts_tf (tp, data);
1526 case TRY_CATCH_EXPR:
1527 remove_useless_stmts_tc (tp, data);
1531 remove_useless_stmts_bind (tp, data);
1535 remove_useless_stmts_goto (tp, data);
1539 remove_useless_stmts_label (tp, data);
1544 data->last_goto = NULL;
1545 data->may_branch = true;
1550 data->last_goto = NULL;
1551 notice_special_calls (t);
1552 update_call_expr_flags (t);
1553 if (tree_could_throw_p (t))
1554 data->may_throw = true;
1558 data->last_goto = NULL;
1560 op = get_call_expr_in (t);
1563 update_call_expr_flags (op);
1564 notice_special_calls (op);
1566 if (tree_could_throw_p (t))
1567 data->may_throw = true;
1570 case STATEMENT_LIST:
1572 tree_stmt_iterator i = tsi_start (t);
1573 while (!tsi_end_p (i))
1576 if (IS_EMPTY_STMT (t))
1582 remove_useless_stmts_1 (tsi_stmt_ptr (i), data);
1585 if (TREE_CODE (t) == STATEMENT_LIST)
1587 tsi_link_before (&i, t, TSI_SAME_STMT);
1597 data->last_goto = NULL;
1601 data->last_goto = NULL;
1607 remove_useless_stmts (void)
1609 struct rus_data data;
1611 clear_special_calls ();
1615 memset (&data, 0, sizeof (data));
1616 remove_useless_stmts_1 (&DECL_SAVED_TREE (current_function_decl), &data);
1618 while (data.repeat);
1622 struct tree_opt_pass pass_remove_useless_stmts =
1624 "useless", /* name */
1626 remove_useless_stmts, /* execute */
1629 0, /* static_pass_number */
1631 PROP_gimple_any, /* properties_required */
1632 0, /* properties_provided */
1633 0, /* properties_destroyed */
1634 0, /* todo_flags_start */
1635 TODO_dump_func, /* todo_flags_finish */
1640 /* Remove obviously useless statements in basic block BB. */
1643 cfg_remove_useless_stmts_bb (basic_block bb)
1645 block_stmt_iterator bsi;
1646 tree stmt = NULL_TREE;
1647 tree cond, var = NULL_TREE, val = NULL_TREE;
1648 struct var_ann_d *ann;
1650 /* Check whether we come here from a condition, and if so, get the
1652 if (EDGE_COUNT (bb->preds) != 1
1653 || !(EDGE_PRED (bb, 0)->flags & (EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
1656 cond = COND_EXPR_COND (last_stmt (EDGE_PRED (bb, 0)->src));
1658 if (TREE_CODE (cond) == VAR_DECL || TREE_CODE (cond) == PARM_DECL)
1661 val = (EDGE_PRED (bb, 0)->flags & EDGE_FALSE_VALUE
1662 ? boolean_false_node : boolean_true_node);
1664 else if (TREE_CODE (cond) == TRUTH_NOT_EXPR
1665 && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL
1666 || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL))
1668 var = TREE_OPERAND (cond, 0);
1669 val = (EDGE_PRED (bb, 0)->flags & EDGE_FALSE_VALUE
1670 ? boolean_true_node : boolean_false_node);
1674 if (EDGE_PRED (bb, 0)->flags & EDGE_FALSE_VALUE)
1675 cond = invert_truthvalue (cond);
1676 if (TREE_CODE (cond) == EQ_EXPR
1677 && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL
1678 || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL)
1679 && (TREE_CODE (TREE_OPERAND (cond, 1)) == VAR_DECL
1680 || TREE_CODE (TREE_OPERAND (cond, 1)) == PARM_DECL
1681 || TREE_CONSTANT (TREE_OPERAND (cond, 1))))
1683 var = TREE_OPERAND (cond, 0);
1684 val = TREE_OPERAND (cond, 1);
1690 /* Only work for normal local variables. */
1691 ann = var_ann (var);
1694 || TREE_ADDRESSABLE (var))
1697 if (! TREE_CONSTANT (val))
1699 ann = var_ann (val);
1702 || TREE_ADDRESSABLE (val))
1706 /* Ignore floating point variables, since comparison behaves weird for
1708 if (FLOAT_TYPE_P (TREE_TYPE (var)))
1711 for (bsi = bsi_start (bb); !bsi_end_p (bsi);)
1713 stmt = bsi_stmt (bsi);
1715 /* If the THEN/ELSE clause merely assigns a value to a variable/parameter
1716 which is already known to contain that value, then remove the useless
1717 THEN/ELSE clause. */
1718 if (TREE_CODE (stmt) == MODIFY_EXPR
1719 && TREE_OPERAND (stmt, 0) == var
1720 && operand_equal_p (val, TREE_OPERAND (stmt, 1), 0))
1726 /* Invalidate the var if we encounter something that could modify it.
1727 Likewise for the value it was previously set to. Note that we only
1728 consider values that are either a VAR_DECL or PARM_DECL so we
1729 can test for conflict very simply. */
1730 if (TREE_CODE (stmt) == ASM_EXPR
1731 || (TREE_CODE (stmt) == MODIFY_EXPR
1732 && (TREE_OPERAND (stmt, 0) == var
1733 || TREE_OPERAND (stmt, 0) == val)))
1741 /* A CFG-aware version of remove_useless_stmts. */
1744 cfg_remove_useless_stmts (void)
1748 #ifdef ENABLE_CHECKING
1749 verify_flow_info ();
1754 cfg_remove_useless_stmts_bb (bb);
1759 /* Remove PHI nodes associated with basic block BB and all edges out of BB. */
1762 remove_phi_nodes_and_edges_for_unreachable_block (basic_block bb)
1766 /* Since this block is no longer reachable, we can just delete all
1767 of its PHI nodes. */
1768 phi = phi_nodes (bb);
1771 tree next = PHI_CHAIN (phi);
1772 remove_phi_node (phi, NULL_TREE, bb);
1776 /* Remove edges to BB's successors. */
1777 while (EDGE_COUNT (bb->succs) > 0)
1778 ssa_remove_edge (EDGE_SUCC (bb, 0));
1782 /* Remove statements of basic block BB. */
1785 remove_bb (basic_block bb)
1787 block_stmt_iterator i;
1788 source_locus loc = 0;
1792 fprintf (dump_file, "Removing basic block %d\n", bb->index);
1793 if (dump_flags & TDF_DETAILS)
1795 dump_bb (bb, dump_file, 0);
1796 fprintf (dump_file, "\n");
1800 /* Remove all the instructions in the block. */
1801 for (i = bsi_start (bb); !bsi_end_p (i); bsi_remove (&i))
1803 tree stmt = bsi_stmt (i);
1804 release_defs (stmt);
1806 set_bb_for_stmt (stmt, NULL);
1808 /* Don't warn for removed gotos. Gotos are often removed due to
1809 jump threading, thus resulting in bogus warnings. Not great,
1810 since this way we lose warnings for gotos in the original
1811 program that are indeed unreachable. */
1812 if (TREE_CODE (stmt) != GOTO_EXPR && EXPR_HAS_LOCATION (stmt) && !loc)
1813 #ifdef USE_MAPPED_LOCATION
1814 loc = EXPR_LOCATION (stmt);
1816 loc = EXPR_LOCUS (stmt);
1820 /* If requested, give a warning that the first statement in the
1821 block is unreachable. We walk statements backwards in the
1822 loop above, so the last statement we process is the first statement
1824 if (warn_notreached && loc)
1825 #ifdef USE_MAPPED_LOCATION
1826 warning ("%Hwill never be executed", &loc);
1828 warning ("%Hwill never be executed", loc);
1831 remove_phi_nodes_and_edges_for_unreachable_block (bb);
1835 /* Examine BB to determine if it is a forwarding block (a block which only
1836 transfers control to a new destination). If BB is a forwarding block,
1837 then return the edge leading to the ultimate destination. */
1840 tree_block_forwards_to (basic_block bb)
1842 block_stmt_iterator bsi;
1843 bb_ann_t ann = bb_ann (bb);
1846 /* If this block is not forwardable, then avoid useless work. */
1847 if (! ann->forwardable)
1850 /* Set this block to not be forwardable. This prevents infinite loops since
1851 any block currently under examination is considered non-forwardable. */
1852 ann->forwardable = 0;
1854 /* No forwarding is possible if this block is a special block (ENTRY/EXIT),
1855 this block has more than one successor, this block's single successor is
1856 reached via an abnormal edge, this block has phi nodes, or this block's
1857 single successor has phi nodes. */
1858 if (bb == EXIT_BLOCK_PTR
1859 || bb == ENTRY_BLOCK_PTR
1860 || EDGE_COUNT (bb->succs) != 1
1861 || EDGE_SUCC (bb, 0)->dest == EXIT_BLOCK_PTR
1862 || (EDGE_SUCC (bb, 0)->flags & EDGE_ABNORMAL) != 0
1864 || phi_nodes (EDGE_SUCC (bb, 0)->dest))
1867 /* Walk past any labels at the start of this block. */
1868 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
1870 stmt = bsi_stmt (bsi);
1871 if (TREE_CODE (stmt) != LABEL_EXPR)
1875 /* If we reached the end of this block we may be able to optimize this
1877 if (bsi_end_p (bsi))
1881 /* Recursive call to pick up chains of forwarding blocks. */
1882 dest = tree_block_forwards_to (EDGE_SUCC (bb, 0)->dest);
1884 /* If none found, we forward to bb->succs[0] at minimum. */
1886 dest = EDGE_SUCC (bb, 0);
1888 ann->forwardable = 1;
1892 /* No forwarding possible. */
1897 /* Try to remove superfluous control structures. */
1900 cleanup_control_flow (void)
1903 block_stmt_iterator bsi;
1904 bool retval = false;
1909 bsi = bsi_last (bb);
1911 if (bsi_end_p (bsi))
1914 stmt = bsi_stmt (bsi);
1915 if (TREE_CODE (stmt) == COND_EXPR
1916 || TREE_CODE (stmt) == SWITCH_EXPR)
1917 retval |= cleanup_control_expr_graph (bb, bsi);
1923 /* Disconnect an unreachable block in the control expression starting
1927 cleanup_control_expr_graph (basic_block bb, block_stmt_iterator bsi)
1930 bool retval = false;
1931 tree expr = bsi_stmt (bsi), val;
1933 if (EDGE_COUNT (bb->succs) > 1)
1938 switch (TREE_CODE (expr))
1941 val = COND_EXPR_COND (expr);
1945 val = SWITCH_COND (expr);
1946 if (TREE_CODE (val) != INTEGER_CST)
1954 taken_edge = find_taken_edge (bb, val);
1958 /* Remove all the edges except the one that is always executed. */
1959 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
1961 if (e != taken_edge)
1963 taken_edge->probability += e->probability;
1964 taken_edge->count += e->count;
1965 ssa_remove_edge (e);
1971 if (taken_edge->probability > REG_BR_PROB_BASE)
1972 taken_edge->probability = REG_BR_PROB_BASE;
1975 taken_edge = EDGE_SUCC (bb, 0);
1978 taken_edge->flags = EDGE_FALLTHRU;
1980 /* We removed some paths from the cfg. */
1981 if (dom_computed[CDI_DOMINATORS] >= DOM_CONS_OK)
1982 dom_computed[CDI_DOMINATORS] = DOM_CONS_OK;
1988 /* Given a control block BB and a predicate VAL, return the edge that
1989 will be taken out of the block. If VAL does not match a unique
1990 edge, NULL is returned. */
1993 find_taken_edge (basic_block bb, tree val)
1997 stmt = last_stmt (bb);
2000 gcc_assert (is_ctrl_stmt (stmt));
2002 /* If VAL is a predicate of the form N RELOP N, where N is an
2003 SSA_NAME, we can usually determine its truth value. */
2004 if (val && COMPARISON_CLASS_P (val))
2007 /* If VAL is not a constant, we can't determine which edge might
2009 if (val == NULL || !really_constant_p (val))
2012 if (TREE_CODE (stmt) == COND_EXPR)
2013 return find_taken_edge_cond_expr (bb, val);
2015 if (TREE_CODE (stmt) == SWITCH_EXPR)
2016 return find_taken_edge_switch_expr (bb, val);
2018 return EDGE_SUCC (bb, 0);
2022 /* Given a constant value VAL and the entry block BB to a COND_EXPR
2023 statement, determine which of the two edges will be taken out of the
2024 block. Return NULL if either edge may be taken. */
2027 find_taken_edge_cond_expr (basic_block bb, tree val)
2029 edge true_edge, false_edge;
2031 extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
2033 /* If both edges of the branch lead to the same basic block, it doesn't
2034 matter which edge is taken. */
2035 if (true_edge->dest == false_edge->dest)
2038 /* Otherwise, try to determine which branch of the if() will be taken.
2039 If VAL is a constant but it can't be reduced to a 0 or a 1, then
2040 we don't really know which edge will be taken at runtime. This
2041 may happen when comparing addresses (e.g., if (&var1 == 4)). */
2042 if (integer_nonzerop (val))
2044 else if (integer_zerop (val))
2051 /* Given a constant value VAL and the entry block BB to a SWITCH_EXPR
2052 statement, determine which edge will be taken out of the block. Return
2053 NULL if any edge may be taken. */
2056 find_taken_edge_switch_expr (basic_block bb, tree val)
2058 tree switch_expr, taken_case;
2059 basic_block dest_bb;
2062 if (TREE_CODE (val) != INTEGER_CST)
2065 switch_expr = last_stmt (bb);
2066 taken_case = find_case_label_for_value (switch_expr, val);
2067 dest_bb = label_to_block (CASE_LABEL (taken_case));
2069 e = find_edge (bb, dest_bb);
2075 /* Return the CASE_LABEL_EXPR that SWITCH_EXPR will take for VAL.
2076 We can make optimal use here of the fact that the case labels are
2077 sorted: We can do a binary search for a case matching VAL. */
2080 find_case_label_for_value (tree switch_expr, tree val)
2082 tree vec = SWITCH_LABELS (switch_expr);
2083 size_t low, high, n = TREE_VEC_LENGTH (vec);
2084 tree default_case = TREE_VEC_ELT (vec, n - 1);
2086 for (low = -1, high = n - 1; high - low > 1; )
2088 size_t i = (high + low) / 2;
2089 tree t = TREE_VEC_ELT (vec, i);
2092 /* Cache the result of comparing CASE_LOW and val. */
2093 cmp = tree_int_cst_compare (CASE_LOW (t), val);
2100 if (CASE_HIGH (t) == NULL)
2102 /* A singe-valued case label. */
2108 /* A case range. We can only handle integer ranges. */
2109 if (cmp <= 0 && tree_int_cst_compare (CASE_HIGH (t), val) >= 0)
2114 return default_case;
2118 /* If all the PHI nodes in DEST have alternatives for E1 and E2 and
2119 those alternatives are equal in each of the PHI nodes, then return
2120 true, else return false. */
2123 phi_alternatives_equal (basic_block dest, edge e1, edge e2)
2125 tree phi, val1, val2;
2128 for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi))
2130 n1 = phi_arg_from_edge (phi, e1);
2131 n2 = phi_arg_from_edge (phi, e2);
2133 gcc_assert (n1 >= 0);
2134 gcc_assert (n2 >= 0);
2136 val1 = PHI_ARG_DEF (phi, n1);
2137 val2 = PHI_ARG_DEF (phi, n2);
2139 if (!operand_equal_p (val1, val2, 0))
2147 /*---------------------------------------------------------------------------
2149 ---------------------------------------------------------------------------*/
2151 /* Dump tree-specific information of block BB to file OUTF. */
2154 tree_dump_bb (basic_block bb, FILE *outf, int indent)
2156 dump_generic_bb (outf, bb, indent, TDF_VOPS);
2160 /* Dump a basic block on stderr. */
2163 debug_tree_bb (basic_block bb)
2165 dump_bb (bb, stderr, 0);
2169 /* Dump basic block with index N on stderr. */
2172 debug_tree_bb_n (int n)
2174 debug_tree_bb (BASIC_BLOCK (n));
2175 return BASIC_BLOCK (n);
2179 /* Dump the CFG on stderr.
2181 FLAGS are the same used by the tree dumping functions
2182 (see TDF_* in tree.h). */
2185 debug_tree_cfg (int flags)
2187 dump_tree_cfg (stderr, flags);
2191 /* Dump the program showing basic block boundaries on the given FILE.
2193 FLAGS are the same used by the tree dumping functions (see TDF_* in
2197 dump_tree_cfg (FILE *file, int flags)
2199 if (flags & TDF_DETAILS)
2201 const char *funcname
2202 = lang_hooks.decl_printable_name (current_function_decl, 2);
2205 fprintf (file, ";; Function %s\n\n", funcname);
2206 fprintf (file, ";; \n%d basic blocks, %d edges, last basic block %d.\n\n",
2207 n_basic_blocks, n_edges, last_basic_block);
2209 brief_dump_cfg (file);
2210 fprintf (file, "\n");
2213 if (flags & TDF_STATS)
2214 dump_cfg_stats (file);
2216 dump_function_to_file (current_function_decl, file, flags | TDF_BLOCKS);
2220 /* Dump CFG statistics on FILE. */
2223 dump_cfg_stats (FILE *file)
2225 static long max_num_merged_labels = 0;
2226 unsigned long size, total = 0;
2229 const char * const fmt_str = "%-30s%-13s%12s\n";
2230 const char * const fmt_str_1 = "%-30s%13d%11lu%c\n";
2231 const char * const fmt_str_3 = "%-43s%11lu%c\n";
2232 const char *funcname
2233 = lang_hooks.decl_printable_name (current_function_decl, 2);
2236 fprintf (file, "\nCFG Statistics for %s\n\n", funcname);
2238 fprintf (file, "---------------------------------------------------------\n");
2239 fprintf (file, fmt_str, "", " Number of ", "Memory");
2240 fprintf (file, fmt_str, "", " instances ", "used ");
2241 fprintf (file, "---------------------------------------------------------\n");
2243 size = n_basic_blocks * sizeof (struct basic_block_def);
2245 fprintf (file, fmt_str_1, "Basic blocks", n_basic_blocks,
2246 SCALE (size), LABEL (size));
2250 n_edges += EDGE_COUNT (bb->succs);
2251 size = n_edges * sizeof (struct edge_def);
2253 fprintf (file, fmt_str_1, "Edges", n_edges, SCALE (size), LABEL (size));
2255 size = n_basic_blocks * sizeof (struct bb_ann_d);
2257 fprintf (file, fmt_str_1, "Basic block annotations", n_basic_blocks,
2258 SCALE (size), LABEL (size));
2260 fprintf (file, "---------------------------------------------------------\n");
2261 fprintf (file, fmt_str_3, "Total memory used by CFG data", SCALE (total),
2263 fprintf (file, "---------------------------------------------------------\n");
2264 fprintf (file, "\n");
2266 if (cfg_stats.num_merged_labels > max_num_merged_labels)
2267 max_num_merged_labels = cfg_stats.num_merged_labels;
2269 fprintf (file, "Coalesced label blocks: %ld (Max so far: %ld)\n",
2270 cfg_stats.num_merged_labels, max_num_merged_labels);
2272 fprintf (file, "\n");
2276 /* Dump CFG statistics on stderr. Keep extern so that it's always
2277 linked in the final executable. */
2280 debug_cfg_stats (void)
2282 dump_cfg_stats (stderr);
2286 /* Dump the flowgraph to a .vcg FILE. */
2289 tree_cfg2vcg (FILE *file)
2294 const char *funcname
2295 = lang_hooks.decl_printable_name (current_function_decl, 2);
2297 /* Write the file header. */
2298 fprintf (file, "graph: { title: \"%s\"\n", funcname);
2299 fprintf (file, "node: { title: \"ENTRY\" label: \"ENTRY\" }\n");
2300 fprintf (file, "node: { title: \"EXIT\" label: \"EXIT\" }\n");
2302 /* Write blocks and edges. */
2303 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
2305 fprintf (file, "edge: { sourcename: \"ENTRY\" targetname: \"%d\"",
2308 if (e->flags & EDGE_FAKE)
2309 fprintf (file, " linestyle: dotted priority: 10");
2311 fprintf (file, " linestyle: solid priority: 100");
2313 fprintf (file, " }\n");
2319 enum tree_code head_code, end_code;
2320 const char *head_name, *end_name;
2323 tree first = first_stmt (bb);
2324 tree last = last_stmt (bb);
2328 head_code = TREE_CODE (first);
2329 head_name = tree_code_name[head_code];
2330 head_line = get_lineno (first);
2333 head_name = "no-statement";
2337 end_code = TREE_CODE (last);
2338 end_name = tree_code_name[end_code];
2339 end_line = get_lineno (last);
2342 end_name = "no-statement";
2344 fprintf (file, "node: { title: \"%d\" label: \"#%d\\n%s (%d)\\n%s (%d)\"}\n",
2345 bb->index, bb->index, head_name, head_line, end_name,
2348 FOR_EACH_EDGE (e, ei, bb->succs)
2350 if (e->dest == EXIT_BLOCK_PTR)
2351 fprintf (file, "edge: { sourcename: \"%d\" targetname: \"EXIT\"", bb->index);
2353 fprintf (file, "edge: { sourcename: \"%d\" targetname: \"%d\"", bb->index, e->dest->index);
2355 if (e->flags & EDGE_FAKE)
2356 fprintf (file, " priority: 10 linestyle: dotted");
2358 fprintf (file, " priority: 100 linestyle: solid");
2360 fprintf (file, " }\n");
2363 if (bb->next_bb != EXIT_BLOCK_PTR)
2367 fputs ("}\n\n", file);
2372 /*---------------------------------------------------------------------------
2373 Miscellaneous helpers
2374 ---------------------------------------------------------------------------*/
2376 /* Return true if T represents a stmt that always transfers control. */
2379 is_ctrl_stmt (tree t)
2381 return (TREE_CODE (t) == COND_EXPR
2382 || TREE_CODE (t) == SWITCH_EXPR
2383 || TREE_CODE (t) == GOTO_EXPR
2384 || TREE_CODE (t) == RETURN_EXPR
2385 || TREE_CODE (t) == RESX_EXPR);
2389 /* Return true if T is a statement that may alter the flow of control
2390 (e.g., a call to a non-returning function). */
2393 is_ctrl_altering_stmt (tree t)
2398 call = get_call_expr_in (t);
2401 /* A non-pure/const CALL_EXPR alters flow control if the current
2402 function has nonlocal labels. */
2403 if (TREE_SIDE_EFFECTS (call) && current_function_has_nonlocal_label)
2406 /* A CALL_EXPR also alters control flow if it does not return. */
2407 if (call_expr_flags (call) & (ECF_NORETURN | ECF_LONGJMP))
2411 /* If a statement can throw, it alters control flow. */
2412 return tree_can_throw_internal (t);
2416 /* Return true if T is a computed goto. */
2419 computed_goto_p (tree t)
2421 return (TREE_CODE (t) == GOTO_EXPR
2422 && TREE_CODE (GOTO_DESTINATION (t)) != LABEL_DECL);
2426 /* Checks whether EXPR is a simple local goto. */
2429 simple_goto_p (tree expr)
2431 return (TREE_CODE (expr) == GOTO_EXPR
2432 && TREE_CODE (GOTO_DESTINATION (expr)) == LABEL_DECL);
2436 /* Return true if T should start a new basic block. PREV_T is the
2437 statement preceding T. It is used when T is a label or a case label.
2438 Labels should only start a new basic block if their previous statement
2439 wasn't a label. Otherwise, sequence of labels would generate
2440 unnecessary basic blocks that only contain a single label. */
2443 stmt_starts_bb_p (tree t, tree prev_t)
2445 enum tree_code code;
2450 /* LABEL_EXPRs start a new basic block only if the preceding
2451 statement wasn't a label of the same type. This prevents the
2452 creation of consecutive blocks that have nothing but a single
2454 code = TREE_CODE (t);
2455 if (code == LABEL_EXPR)
2457 /* Nonlocal and computed GOTO targets always start a new block. */
2458 if (code == LABEL_EXPR
2459 && (DECL_NONLOCAL (LABEL_EXPR_LABEL (t))
2460 || FORCED_LABEL (LABEL_EXPR_LABEL (t))))
2463 if (prev_t && TREE_CODE (prev_t) == code)
2465 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (prev_t)))
2468 cfg_stats.num_merged_labels++;
2479 /* Return true if T should end a basic block. */
2482 stmt_ends_bb_p (tree t)
2484 return is_ctrl_stmt (t) || is_ctrl_altering_stmt (t);
2488 /* Add gotos that used to be represented implicitly in the CFG. */
2491 disband_implicit_edges (void)
2494 block_stmt_iterator last;
2501 last = bsi_last (bb);
2502 stmt = last_stmt (bb);
2504 if (stmt && TREE_CODE (stmt) == COND_EXPR)
2506 /* Remove superfluous gotos from COND_EXPR branches. Moved
2507 from cfg_remove_useless_stmts here since it violates the
2508 invariants for tree--cfg correspondence and thus fits better
2509 here where we do it anyway. */
2510 FOR_EACH_EDGE (e, ei, bb->succs)
2512 if (e->dest != bb->next_bb)
2515 if (e->flags & EDGE_TRUE_VALUE)
2516 COND_EXPR_THEN (stmt) = build_empty_stmt ();
2517 else if (e->flags & EDGE_FALSE_VALUE)
2518 COND_EXPR_ELSE (stmt) = build_empty_stmt ();
2521 e->flags |= EDGE_FALLTHRU;
2527 if (stmt && TREE_CODE (stmt) == RETURN_EXPR)
2529 /* Remove the RETURN_EXPR if we may fall though to the exit
2531 gcc_assert (EDGE_COUNT (bb->succs) == 1);
2532 gcc_assert (EDGE_SUCC (bb, 0)->dest == EXIT_BLOCK_PTR);
2534 if (bb->next_bb == EXIT_BLOCK_PTR
2535 && !TREE_OPERAND (stmt, 0))
2538 EDGE_SUCC (bb, 0)->flags |= EDGE_FALLTHRU;
2543 /* There can be no fallthru edge if the last statement is a control
2545 if (stmt && is_ctrl_stmt (stmt))
2548 /* Find a fallthru edge and emit the goto if necessary. */
2549 FOR_EACH_EDGE (e, ei, bb->succs)
2550 if (e->flags & EDGE_FALLTHRU)
2553 if (!e || e->dest == bb->next_bb)
2556 gcc_assert (e->dest != EXIT_BLOCK_PTR);
2557 label = tree_block_label (e->dest);
2559 stmt = build1 (GOTO_EXPR, void_type_node, label);
2560 #ifdef USE_MAPPED_LOCATION
2561 SET_EXPR_LOCATION (stmt, e->goto_locus);
2563 SET_EXPR_LOCUS (stmt, e->goto_locus);
2565 bsi_insert_after (&last, stmt, BSI_NEW_STMT);
2566 e->flags &= ~EDGE_FALLTHRU;
2570 /* Remove block annotations and other datastructures. */
2573 delete_tree_cfg_annotations (void)
2576 if (n_basic_blocks > 0)
2577 free_blocks_annotations ();
2579 label_to_block_map = NULL;
2586 /* Return the first statement in basic block BB. */
2589 first_stmt (basic_block bb)
2591 block_stmt_iterator i = bsi_start (bb);
2592 return !bsi_end_p (i) ? bsi_stmt (i) : NULL_TREE;
2596 /* Return the last statement in basic block BB. */
2599 last_stmt (basic_block bb)
2601 block_stmt_iterator b = bsi_last (bb);
2602 return !bsi_end_p (b) ? bsi_stmt (b) : NULL_TREE;
2606 /* Return a pointer to the last statement in block BB. */
2609 last_stmt_ptr (basic_block bb)
2611 block_stmt_iterator last = bsi_last (bb);
2612 return !bsi_end_p (last) ? bsi_stmt_ptr (last) : NULL;
2616 /* Return the last statement of an otherwise empty block. Return NULL
2617 if the block is totally empty, or if it contains more than one
2621 last_and_only_stmt (basic_block bb)
2623 block_stmt_iterator i = bsi_last (bb);
2629 last = bsi_stmt (i);
2634 /* Empty statements should no longer appear in the instruction stream.
2635 Everything that might have appeared before should be deleted by
2636 remove_useless_stmts, and the optimizers should just bsi_remove
2637 instead of smashing with build_empty_stmt.
2639 Thus the only thing that should appear here in a block containing
2640 one executable statement is a label. */
2641 prev = bsi_stmt (i);
2642 if (TREE_CODE (prev) == LABEL_EXPR)
2649 /* Mark BB as the basic block holding statement T. */
2652 set_bb_for_stmt (tree t, basic_block bb)
2654 if (TREE_CODE (t) == PHI_NODE)
2656 else if (TREE_CODE (t) == STATEMENT_LIST)
2658 tree_stmt_iterator i;
2659 for (i = tsi_start (t); !tsi_end_p (i); tsi_next (&i))
2660 set_bb_for_stmt (tsi_stmt (i), bb);
2664 stmt_ann_t ann = get_stmt_ann (t);
2667 /* If the statement is a label, add the label to block-to-labels map
2668 so that we can speed up edge creation for GOTO_EXPRs. */
2669 if (TREE_CODE (t) == LABEL_EXPR)
2673 t = LABEL_EXPR_LABEL (t);
2674 uid = LABEL_DECL_UID (t);
2677 LABEL_DECL_UID (t) = uid = cfun->last_label_uid++;
2678 if (VARRAY_SIZE (label_to_block_map) <= (unsigned) uid)
2679 VARRAY_GROW (label_to_block_map, 3 * uid / 2);
2682 /* We're moving an existing label. Make sure that we've
2683 removed it from the old block. */
2684 gcc_assert (!bb || !VARRAY_BB (label_to_block_map, uid));
2685 VARRAY_BB (label_to_block_map, uid) = bb;
2690 /* Finds iterator for STMT. */
2692 extern block_stmt_iterator
2693 stmt_for_bsi (tree stmt)
2695 block_stmt_iterator bsi;
2697 for (bsi = bsi_start (bb_for_stmt (stmt)); !bsi_end_p (bsi); bsi_next (&bsi))
2698 if (bsi_stmt (bsi) == stmt)
2704 /* Insert statement (or statement list) T before the statement
2705 pointed-to by iterator I. M specifies how to update iterator I
2706 after insertion (see enum bsi_iterator_update). */
2709 bsi_insert_before (block_stmt_iterator *i, tree t, enum bsi_iterator_update m)
2711 set_bb_for_stmt (t, i->bb);
2712 tsi_link_before (&i->tsi, t, m);
2717 /* Insert statement (or statement list) T after the statement
2718 pointed-to by iterator I. M specifies how to update iterator I
2719 after insertion (see enum bsi_iterator_update). */
2722 bsi_insert_after (block_stmt_iterator *i, tree t, enum bsi_iterator_update m)
2724 set_bb_for_stmt (t, i->bb);
2725 tsi_link_after (&i->tsi, t, m);
2730 /* Remove the statement pointed to by iterator I. The iterator is updated
2731 to the next statement. */
2734 bsi_remove (block_stmt_iterator *i)
2736 tree t = bsi_stmt (*i);
2737 set_bb_for_stmt (t, NULL);
2738 tsi_delink (&i->tsi);
2742 /* Move the statement at FROM so it comes right after the statement at TO. */
2745 bsi_move_after (block_stmt_iterator *from, block_stmt_iterator *to)
2747 tree stmt = bsi_stmt (*from);
2749 bsi_insert_after (to, stmt, BSI_SAME_STMT);
2753 /* Move the statement at FROM so it comes right before the statement at TO. */
2756 bsi_move_before (block_stmt_iterator *from, block_stmt_iterator *to)
2758 tree stmt = bsi_stmt (*from);
2760 bsi_insert_before (to, stmt, BSI_SAME_STMT);
2764 /* Move the statement at FROM to the end of basic block BB. */
2767 bsi_move_to_bb_end (block_stmt_iterator *from, basic_block bb)
2769 block_stmt_iterator last = bsi_last (bb);
2771 /* Have to check bsi_end_p because it could be an empty block. */
2772 if (!bsi_end_p (last) && is_ctrl_stmt (bsi_stmt (last)))
2773 bsi_move_before (from, &last);
2775 bsi_move_after (from, &last);
2779 /* Replace the contents of the statement pointed to by iterator BSI
2780 with STMT. If PRESERVE_EH_INFO is true, the exception handling
2781 information of the original statement is preserved. */
2784 bsi_replace (const block_stmt_iterator *bsi, tree stmt, bool preserve_eh_info)
2787 tree orig_stmt = bsi_stmt (*bsi);
2789 SET_EXPR_LOCUS (stmt, EXPR_LOCUS (orig_stmt));
2790 set_bb_for_stmt (stmt, bsi->bb);
2792 /* Preserve EH region information from the original statement, if
2793 requested by the caller. */
2794 if (preserve_eh_info)
2796 eh_region = lookup_stmt_eh_region (orig_stmt);
2798 add_stmt_to_eh_region (stmt, eh_region);
2801 *bsi_stmt_ptr (*bsi) = stmt;
2806 /* Insert the statement pointed-to by BSI into edge E. Every attempt
2807 is made to place the statement in an existing basic block, but
2808 sometimes that isn't possible. When it isn't possible, the edge is
2809 split and the statement is added to the new block.
2811 In all cases, the returned *BSI points to the correct location. The
2812 return value is true if insertion should be done after the location,
2813 or false if it should be done before the location. If new basic block
2814 has to be created, it is stored in *NEW_BB. */
2817 tree_find_edge_insert_loc (edge e, block_stmt_iterator *bsi,
2818 basic_block *new_bb)
2820 basic_block dest, src;
2826 /* If the destination has one predecessor which has no PHI nodes,
2827 insert there. Except for the exit block.
2829 The requirement for no PHI nodes could be relaxed. Basically we
2830 would have to examine the PHIs to prove that none of them used
2831 the value set by the statement we want to insert on E. That
2832 hardly seems worth the effort. */
2833 if (EDGE_COUNT (dest->preds) == 1
2834 && ! phi_nodes (dest)
2835 && dest != EXIT_BLOCK_PTR)
2837 *bsi = bsi_start (dest);
2838 if (bsi_end_p (*bsi))
2841 /* Make sure we insert after any leading labels. */
2842 tmp = bsi_stmt (*bsi);
2843 while (TREE_CODE (tmp) == LABEL_EXPR)
2846 if (bsi_end_p (*bsi))
2848 tmp = bsi_stmt (*bsi);
2851 if (bsi_end_p (*bsi))
2853 *bsi = bsi_last (dest);
2860 /* If the source has one successor, the edge is not abnormal and
2861 the last statement does not end a basic block, insert there.
2862 Except for the entry block. */
2864 if ((e->flags & EDGE_ABNORMAL) == 0
2865 && EDGE_COUNT (src->succs) == 1
2866 && src != ENTRY_BLOCK_PTR)
2868 *bsi = bsi_last (src);
2869 if (bsi_end_p (*bsi))
2872 tmp = bsi_stmt (*bsi);
2873 if (!stmt_ends_bb_p (tmp))
2876 /* Insert code just before returning the value. We may need to decompose
2877 the return in the case it contains non-trivial operand. */
2878 if (TREE_CODE (tmp) == RETURN_EXPR)
2880 tree op = TREE_OPERAND (tmp, 0);
2881 if (!is_gimple_val (op))
2883 gcc_assert (TREE_CODE (op) == MODIFY_EXPR);
2884 bsi_insert_before (bsi, op, BSI_NEW_STMT);
2885 TREE_OPERAND (tmp, 0) = TREE_OPERAND (op, 0);
2892 /* Otherwise, create a new basic block, and split this edge. */
2893 dest = split_edge (e);
2896 e = EDGE_PRED (dest, 0);
2901 /* This routine will commit all pending edge insertions, creating any new
2902 basic blocks which are necessary.
2904 If specified, NEW_BLOCKS returns a count of the number of new basic
2905 blocks which were created. */
2908 bsi_commit_edge_inserts (int *new_blocks)
2915 blocks = n_basic_blocks;
2917 bsi_commit_edge_inserts_1 (EDGE_SUCC (ENTRY_BLOCK_PTR, 0));
2920 FOR_EACH_EDGE (e, ei, bb->succs)
2921 bsi_commit_edge_inserts_1 (e);
2924 *new_blocks = n_basic_blocks - blocks;
2928 /* Commit insertions pending at edge E. */
2931 bsi_commit_edge_inserts_1 (edge e)
2933 if (PENDING_STMT (e))
2935 block_stmt_iterator bsi;
2936 tree stmt = PENDING_STMT (e);
2938 PENDING_STMT (e) = NULL_TREE;
2940 if (tree_find_edge_insert_loc (e, &bsi, NULL))
2941 bsi_insert_after (&bsi, stmt, BSI_NEW_STMT);
2943 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
2948 /* Add STMT to the pending list of edge E. No actual insertion is
2949 made until a call to bsi_commit_edge_inserts () is made. */
2952 bsi_insert_on_edge (edge e, tree stmt)
2954 append_to_statement_list (stmt, &PENDING_STMT (e));
2957 /* Similar to bsi_insert_on_edge+bsi_commit_edge_inserts. If new block has to
2958 be created, it is returned. */
2961 bsi_insert_on_edge_immediate (edge e, tree stmt)
2963 block_stmt_iterator bsi;
2964 basic_block new_bb = NULL;
2966 gcc_assert (!PENDING_STMT (e));
2968 if (tree_find_edge_insert_loc (e, &bsi, &new_bb))
2969 bsi_insert_after (&bsi, stmt, BSI_NEW_STMT);
2971 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
2976 /*---------------------------------------------------------------------------
2977 Tree specific functions for CFG manipulation
2978 ---------------------------------------------------------------------------*/
2980 /* Split a (typically critical) edge EDGE_IN. Return the new block.
2981 Abort on abnormal edges. */
2984 tree_split_edge (edge edge_in)
2986 basic_block new_bb, after_bb, dest, src;
2992 /* Abnormal edges cannot be split. */
2993 gcc_assert (!(edge_in->flags & EDGE_ABNORMAL));
2996 dest = edge_in->dest;
2998 /* Place the new block in the block list. Try to keep the new block
2999 near its "logical" location. This is of most help to humans looking
3000 at debugging dumps. */
3001 FOR_EACH_EDGE (e, ei, dest->preds)
3002 if (e->src->next_bb == dest)
3005 after_bb = dest->prev_bb;
3007 after_bb = edge_in->src;
3009 new_bb = create_empty_bb (after_bb);
3010 new_bb->frequency = EDGE_FREQUENCY (edge_in);
3011 new_bb->count = edge_in->count;
3012 new_edge = make_edge (new_bb, dest, EDGE_FALLTHRU);
3013 new_edge->probability = REG_BR_PROB_BASE;
3014 new_edge->count = edge_in->count;
3016 /* Find all the PHI arguments on the original edge, and change them to
3017 the new edge. Do it before redirection, so that the argument does not
3019 for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi))
3021 num_elem = PHI_NUM_ARGS (phi);
3022 for (i = 0; i < num_elem; i++)
3023 if (PHI_ARG_EDGE (phi, i) == edge_in)
3025 PHI_ARG_EDGE (phi, i) = new_edge;
3030 e = redirect_edge_and_branch (edge_in, new_bb);
3032 gcc_assert (!PENDING_STMT (edge_in));
3038 /* Return true when BB has label LABEL in it. */
3041 has_label_p (basic_block bb, tree label)
3043 block_stmt_iterator bsi;
3045 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3047 tree stmt = bsi_stmt (bsi);
3049 if (TREE_CODE (stmt) != LABEL_EXPR)
3051 if (LABEL_EXPR_LABEL (stmt) == label)
3058 /* Callback for walk_tree, check that all elements with address taken are
3059 properly noticed as such. */
3062 verify_expr (tree *tp, int *walk_subtrees, void *data ATTRIBUTE_UNUSED)
3069 /* Check operand N for being valid GIMPLE and give error MSG if not.
3070 We check for constants explicitly since they are not considered
3071 gimple invariants if they overflowed. */
3072 #define CHECK_OP(N, MSG) \
3073 do { if (!CONSTANT_CLASS_P (TREE_OPERAND (t, N)) \
3074 && !is_gimple_val (TREE_OPERAND (t, N))) \
3075 { error (MSG); return TREE_OPERAND (t, N); }} while (0)
3077 switch (TREE_CODE (t))
3080 if (SSA_NAME_IN_FREE_LIST (t))
3082 error ("SSA name in freelist but still referenced");
3088 x = TREE_OPERAND (t, 0);
3089 if (TREE_CODE (x) == BIT_FIELD_REF
3090 && is_gimple_reg (TREE_OPERAND (x, 0)))
3092 error ("GIMPLE register modified with BIT_FIELD_REF");
3098 /* Skip any references (they will be checked when we recurse down the
3099 tree) and ensure that any variable used as a prefix is marked
3101 for (x = TREE_OPERAND (t, 0);
3102 (handled_component_p (x)
3103 || TREE_CODE (x) == REALPART_EXPR
3104 || TREE_CODE (x) == IMAGPART_EXPR);
3105 x = TREE_OPERAND (x, 0))
3108 if (TREE_CODE (x) != VAR_DECL && TREE_CODE (x) != PARM_DECL)
3110 if (!TREE_ADDRESSABLE (x))
3112 error ("address taken, but ADDRESSABLE bit not set");
3118 x = TREE_OPERAND (t, 0);
3119 if (TREE_CODE (TREE_TYPE (x)) != BOOLEAN_TYPE)
3121 error ("non-boolean used in condition");
3128 case FIX_TRUNC_EXPR:
3130 case FIX_FLOOR_EXPR:
3131 case FIX_ROUND_EXPR:
3136 case NON_LVALUE_EXPR:
3137 case TRUTH_NOT_EXPR:
3138 CHECK_OP (0, "Invalid operand to unary operator");
3145 case ARRAY_RANGE_REF:
3147 case VIEW_CONVERT_EXPR:
3148 /* We have a nest of references. Verify that each of the operands
3149 that determine where to reference is either a constant or a variable,
3150 verify that the base is valid, and then show we've already checked
3152 while (TREE_CODE (t) == REALPART_EXPR || TREE_CODE (t) == IMAGPART_EXPR
3153 || handled_component_p (t))
3155 if (TREE_CODE (t) == COMPONENT_REF && TREE_OPERAND (t, 2))
3156 CHECK_OP (2, "Invalid COMPONENT_REF offset operator");
3157 else if (TREE_CODE (t) == ARRAY_REF
3158 || TREE_CODE (t) == ARRAY_RANGE_REF)
3160 CHECK_OP (1, "Invalid array index.");
3161 if (TREE_OPERAND (t, 2))
3162 CHECK_OP (2, "Invalid array lower bound.");
3163 if (TREE_OPERAND (t, 3))
3164 CHECK_OP (3, "Invalid array stride.");
3166 else if (TREE_CODE (t) == BIT_FIELD_REF)
3168 CHECK_OP (1, "Invalid operand to BIT_FIELD_REF");
3169 CHECK_OP (2, "Invalid operand to BIT_FIELD_REF");
3172 t = TREE_OPERAND (t, 0);
3175 if (!CONSTANT_CLASS_P (t) && !is_gimple_lvalue (t))
3177 error ("Invalid reference prefix.");
3189 case UNORDERED_EXPR:
3200 case TRUNC_DIV_EXPR:
3202 case FLOOR_DIV_EXPR:
3203 case ROUND_DIV_EXPR:
3204 case TRUNC_MOD_EXPR:
3206 case FLOOR_MOD_EXPR:
3207 case ROUND_MOD_EXPR:
3209 case EXACT_DIV_EXPR:
3219 CHECK_OP (0, "Invalid operand to binary operator");
3220 CHECK_OP (1, "Invalid operand to binary operator");
3232 /* Verify STMT, return true if STMT is not in GIMPLE form.
3233 TODO: Implement type checking. */
3236 verify_stmt (tree stmt, bool last_in_block)
3240 if (!is_gimple_stmt (stmt))
3242 error ("Is not a valid GIMPLE statement.");
3246 addr = walk_tree (&stmt, verify_expr, NULL, NULL);
3249 debug_generic_stmt (addr);
3253 /* If the statement is marked as part of an EH region, then it is
3254 expected that the statement could throw. Verify that when we
3255 have optimizations that simplify statements such that we prove
3256 that they cannot throw, that we update other data structures
3258 if (lookup_stmt_eh_region (stmt) >= 0)
3260 if (!tree_could_throw_p (stmt))
3262 error ("Statement marked for throw, but doesn%'t.");
3265 if (!last_in_block && tree_can_throw_internal (stmt))
3267 error ("Statement marked for throw in middle of block.");
3275 debug_generic_stmt (stmt);
3280 /* Return true when the T can be shared. */
3283 tree_node_can_be_shared (tree t)
3285 if (IS_TYPE_OR_DECL_P (t)
3286 /* We check for constants explicitly since they are not considered
3287 gimple invariants if they overflowed. */
3288 || CONSTANT_CLASS_P (t)
3289 || is_gimple_min_invariant (t)
3290 || TREE_CODE (t) == SSA_NAME)
3293 while (((TREE_CODE (t) == ARRAY_REF || TREE_CODE (t) == ARRAY_RANGE_REF)
3294 /* We check for constants explicitly since they are not considered
3295 gimple invariants if they overflowed. */
3296 && (CONSTANT_CLASS_P (TREE_OPERAND (t, 1))
3297 || is_gimple_min_invariant (TREE_OPERAND (t, 1))))
3298 || (TREE_CODE (t) == COMPONENT_REF
3299 || TREE_CODE (t) == REALPART_EXPR
3300 || TREE_CODE (t) == IMAGPART_EXPR))
3301 t = TREE_OPERAND (t, 0);
3310 /* Called via walk_trees. Verify tree sharing. */
3313 verify_node_sharing (tree * tp, int *walk_subtrees, void *data)
3315 htab_t htab = (htab_t) data;
3318 if (tree_node_can_be_shared (*tp))
3320 *walk_subtrees = false;
3324 slot = htab_find_slot (htab, *tp, INSERT);
3333 /* Verify the GIMPLE statement chain. */
3339 block_stmt_iterator bsi;
3344 timevar_push (TV_TREE_STMT_VERIFY);
3345 htab = htab_create (37, htab_hash_pointer, htab_eq_pointer, NULL);
3352 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
3354 int phi_num_args = PHI_NUM_ARGS (phi);
3356 for (i = 0; i < phi_num_args; i++)
3358 tree t = PHI_ARG_DEF (phi, i);
3361 /* Addressable variables do have SSA_NAMEs but they
3362 are not considered gimple values. */
3363 if (TREE_CODE (t) != SSA_NAME
3364 && TREE_CODE (t) != FUNCTION_DECL
3365 && !is_gimple_val (t))
3367 error ("PHI def is not a GIMPLE value");
3368 debug_generic_stmt (phi);
3369 debug_generic_stmt (t);
3373 addr = walk_tree (&t, verify_expr, NULL, NULL);
3376 debug_generic_stmt (addr);
3380 addr = walk_tree (&t, verify_node_sharing, htab, NULL);
3383 error ("Incorrect sharing of tree nodes");
3384 debug_generic_stmt (phi);
3385 debug_generic_stmt (addr);
3391 for (bsi = bsi_start (bb); !bsi_end_p (bsi); )
3393 tree stmt = bsi_stmt (bsi);
3395 err |= verify_stmt (stmt, bsi_end_p (bsi));
3396 addr = walk_tree (&stmt, verify_node_sharing, htab, NULL);
3399 error ("Incorrect sharing of tree nodes");
3400 debug_generic_stmt (stmt);
3401 debug_generic_stmt (addr);
3408 internal_error ("verify_stmts failed.");
3411 timevar_pop (TV_TREE_STMT_VERIFY);
3415 /* Verifies that the flow information is OK. */
3418 tree_verify_flow_info (void)
3422 block_stmt_iterator bsi;
3427 if (ENTRY_BLOCK_PTR->stmt_list)
3429 error ("ENTRY_BLOCK has a statement list associated with it\n");
3433 if (EXIT_BLOCK_PTR->stmt_list)
3435 error ("EXIT_BLOCK has a statement list associated with it\n");
3439 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
3440 if (e->flags & EDGE_FALLTHRU)
3442 error ("Fallthru to exit from bb %d\n", e->src->index);
3448 bool found_ctrl_stmt = false;
3450 /* Skip labels on the start of basic block. */
3451 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3453 if (TREE_CODE (bsi_stmt (bsi)) != LABEL_EXPR)
3456 if (label_to_block (LABEL_EXPR_LABEL (bsi_stmt (bsi))) != bb)
3458 error ("Label %s to block does not match in bb %d\n",
3459 IDENTIFIER_POINTER (DECL_NAME (bsi_stmt (bsi))),
3464 if (decl_function_context (LABEL_EXPR_LABEL (bsi_stmt (bsi)))
3465 != current_function_decl)
3467 error ("Label %s has incorrect context in bb %d\n",
3468 IDENTIFIER_POINTER (DECL_NAME (bsi_stmt (bsi))),
3474 /* Verify that body of basic block BB is free of control flow. */
3475 for (; !bsi_end_p (bsi); bsi_next (&bsi))
3477 tree stmt = bsi_stmt (bsi);
3479 if (found_ctrl_stmt)
3481 error ("Control flow in the middle of basic block %d\n",
3486 if (stmt_ends_bb_p (stmt))
3487 found_ctrl_stmt = true;
3489 if (TREE_CODE (stmt) == LABEL_EXPR)
3491 error ("Label %s in the middle of basic block %d\n",
3492 IDENTIFIER_POINTER (DECL_NAME (stmt)),
3497 bsi = bsi_last (bb);
3498 if (bsi_end_p (bsi))
3501 stmt = bsi_stmt (bsi);
3503 if (is_ctrl_stmt (stmt))
3505 FOR_EACH_EDGE (e, ei, bb->succs)
3506 if (e->flags & EDGE_FALLTHRU)
3508 error ("Fallthru edge after a control statement in bb %d \n",
3514 switch (TREE_CODE (stmt))
3520 if (TREE_CODE (COND_EXPR_THEN (stmt)) != GOTO_EXPR
3521 || TREE_CODE (COND_EXPR_ELSE (stmt)) != GOTO_EXPR)
3523 error ("Structured COND_EXPR at the end of bb %d\n", bb->index);
3527 extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
3529 if (!true_edge || !false_edge
3530 || !(true_edge->flags & EDGE_TRUE_VALUE)
3531 || !(false_edge->flags & EDGE_FALSE_VALUE)
3532 || (true_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL))
3533 || (false_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL))
3534 || EDGE_COUNT (bb->succs) >= 3)
3536 error ("Wrong outgoing edge flags at end of bb %d\n",
3541 if (!has_label_p (true_edge->dest,
3542 GOTO_DESTINATION (COND_EXPR_THEN (stmt))))
3544 error ("%<then%> label does not match edge at end of bb %d\n",
3549 if (!has_label_p (false_edge->dest,
3550 GOTO_DESTINATION (COND_EXPR_ELSE (stmt))))
3552 error ("%<else%> label does not match edge at end of bb %d\n",
3560 if (simple_goto_p (stmt))
3562 error ("Explicit goto at end of bb %d\n", bb->index);
3567 /* FIXME. We should double check that the labels in the
3568 destination blocks have their address taken. */
3569 FOR_EACH_EDGE (e, ei, bb->succs)
3570 if ((e->flags & (EDGE_FALLTHRU | EDGE_TRUE_VALUE
3571 | EDGE_FALSE_VALUE))
3572 || !(e->flags & EDGE_ABNORMAL))
3574 error ("Wrong outgoing edge flags at end of bb %d\n",
3582 if (EDGE_COUNT (bb->succs) != 1
3583 || (EDGE_SUCC (bb, 0)->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL
3584 | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
3586 error ("Wrong outgoing edge flags at end of bb %d\n", bb->index);
3589 if (EDGE_SUCC (bb, 0)->dest != EXIT_BLOCK_PTR)
3591 error ("Return edge does not point to exit in bb %d\n",
3604 vec = SWITCH_LABELS (stmt);
3605 n = TREE_VEC_LENGTH (vec);
3607 /* Mark all the destination basic blocks. */
3608 for (i = 0; i < n; ++i)
3610 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
3611 basic_block label_bb = label_to_block (lab);
3613 gcc_assert (!label_bb->aux || label_bb->aux == (void *)1);
3614 label_bb->aux = (void *)1;
3617 /* Verify that the case labels are sorted. */
3618 prev = TREE_VEC_ELT (vec, 0);
3619 for (i = 1; i < n - 1; ++i)
3621 tree c = TREE_VEC_ELT (vec, i);
3624 error ("Found default case not at end of case vector");
3628 if (! tree_int_cst_lt (CASE_LOW (prev), CASE_LOW (c)))
3630 error ("Case labels not sorted:\n ");
3631 print_generic_expr (stderr, prev, 0);
3632 fprintf (stderr," is greater than ");
3633 print_generic_expr (stderr, c, 0);
3634 fprintf (stderr," but comes before it.\n");
3639 if (CASE_LOW (TREE_VEC_ELT (vec, n - 1)))
3641 error ("No default case found at end of case vector");
3645 FOR_EACH_EDGE (e, ei, bb->succs)
3649 error ("Extra outgoing edge %d->%d\n",
3650 bb->index, e->dest->index);
3653 e->dest->aux = (void *)2;
3654 if ((e->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL
3655 | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
3657 error ("Wrong outgoing edge flags at end of bb %d\n",
3663 /* Check that we have all of them. */
3664 for (i = 0; i < n; ++i)
3666 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
3667 basic_block label_bb = label_to_block (lab);
3669 if (label_bb->aux != (void *)2)
3671 error ("Missing edge %i->%i\n",
3672 bb->index, label_bb->index);
3677 FOR_EACH_EDGE (e, ei, bb->succs)
3678 e->dest->aux = (void *)0;
3685 if (dom_computed[CDI_DOMINATORS] >= DOM_NO_FAST_QUERY)
3686 verify_dominators (CDI_DOMINATORS);
3692 /* Updates phi nodes after creating forwarder block joined
3693 by edge FALLTHRU. */
3696 tree_make_forwarder_block (edge fallthru)
3700 basic_block dummy, bb;
3701 tree phi, new_phi, var, prev, next;
3703 dummy = fallthru->src;
3704 bb = fallthru->dest;
3706 if (EDGE_COUNT (bb->preds) == 1)
3709 /* If we redirected a branch we must create new phi nodes at the
3711 for (phi = phi_nodes (dummy); phi; phi = PHI_CHAIN (phi))
3713 var = PHI_RESULT (phi);
3714 new_phi = create_phi_node (var, bb);
3715 SSA_NAME_DEF_STMT (var) = new_phi;
3716 SET_PHI_RESULT (phi, make_ssa_name (SSA_NAME_VAR (var), phi));
3717 add_phi_arg (&new_phi, PHI_RESULT (phi), fallthru);
3720 /* Ensure that the PHI node chain is in the same order. */
3722 for (phi = phi_nodes (bb); phi; phi = next)
3724 next = PHI_CHAIN (phi);
3725 PHI_CHAIN (phi) = prev;
3728 set_phi_nodes (bb, prev);
3730 /* Add the arguments we have stored on edges. */
3731 FOR_EACH_EDGE (e, ei, bb->preds)
3736 for (phi = phi_nodes (bb), var = PENDING_STMT (e);
3738 phi = PHI_CHAIN (phi), var = TREE_CHAIN (var))
3739 add_phi_arg (&phi, TREE_VALUE (var), e);
3741 PENDING_STMT (e) = NULL;
3746 /* Return true if basic block BB does nothing except pass control
3747 flow to another block and that we can safely insert a label at
3748 the start of the successor block. */
3751 tree_forwarder_block_p (basic_block bb)
3753 block_stmt_iterator bsi;
3757 /* If we have already determined that this block is not forwardable,
3758 then no further checks are necessary. */
3759 if (! bb_ann (bb)->forwardable)
3762 /* BB must have a single outgoing normal edge. Otherwise it can not be
3763 a forwarder block. */
3764 if (EDGE_COUNT (bb->succs) != 1
3765 || EDGE_SUCC (bb, 0)->dest == EXIT_BLOCK_PTR
3766 || (EDGE_SUCC (bb, 0)->flags & EDGE_ABNORMAL)
3767 || bb == ENTRY_BLOCK_PTR)
3769 bb_ann (bb)->forwardable = 0;
3773 /* Successors of the entry block are not forwarders. */
3774 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
3777 bb_ann (bb)->forwardable = 0;
3781 /* BB can not have any PHI nodes. This could potentially be relaxed
3782 early in compilation if we re-rewrote the variables appearing in
3783 any PHI nodes in forwarder blocks. */
3786 bb_ann (bb)->forwardable = 0;
3790 /* Now walk through the statements. We can ignore labels, anything else
3791 means this is not a forwarder block. */
3792 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3794 tree stmt = bsi_stmt (bsi);
3796 switch (TREE_CODE (stmt))
3799 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)))
3804 bb_ann (bb)->forwardable = 0;
3813 /* Thread jumps over empty statements.
3815 This code should _not_ thread over obviously equivalent conditions
3816 as that requires nontrivial updates to the SSA graph. */
3822 basic_block bb, dest, tmp, old_dest, curr, dom;
3825 bool retval = false;
3828 bb_ann (bb)->forwardable = 1;
3830 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb)
3834 /* Don't waste time on unreachable blocks. */
3835 if (EDGE_COUNT (bb->preds) == 0)
3838 /* Nor on forwarders. */
3839 if (tree_forwarder_block_p (bb))
3842 /* This block is now part of a forwarding path, mark it as not
3843 forwardable so that we can detect loops. This bit will be
3845 bb_ann (bb)->forwardable = 0;
3847 /* Examine each of our block's successors to see if it is
3849 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
3854 /* If the edge is abnormal or its destination is not
3855 forwardable, then there's nothing to do. */
3856 if ((e->flags & EDGE_ABNORMAL)
3857 || !tree_forwarder_block_p (e->dest))
3864 freq = EDGE_FREQUENCY (e);
3866 /* Now walk through as many forwarder block as possible to
3867 find the ultimate destination we want to thread our jump
3869 last = EDGE_SUCC (e->dest, 0);
3870 bb_ann (e->dest)->forwardable = 0;
3871 for (dest = EDGE_SUCC (e->dest, 0)->dest;
3872 tree_forwarder_block_p (dest);
3873 last = EDGE_SUCC (dest, 0),
3874 dest = EDGE_SUCC (dest, 0)->dest)
3876 /* An infinite loop detected. We redirect the edge anyway, so
3877 that the loop is shrunk into single basic block. */
3878 if (!bb_ann (dest)->forwardable)
3881 if (EDGE_SUCC (dest, 0)->dest == EXIT_BLOCK_PTR)
3884 bb_ann (dest)->forwardable = 0;
3887 /* Reset the forwardable marks to 1. */
3890 tmp = EDGE_SUCC (tmp, 0)->dest)
3891 bb_ann (tmp)->forwardable = 1;
3893 if (dest == e->dest)
3899 old = find_edge (bb, dest);
3902 /* If there already is an edge, check whether the values
3903 in phi nodes differ. */
3904 if (!phi_alternatives_equal (dest, last, old))
3906 /* The previous block is forwarder. Redirect our jump
3907 to that target instead since we know it has no PHI
3908 nodes that will need updating. */
3911 /* That might mean that no forwarding at all is possible. */
3912 if (dest == e->dest)
3918 old = find_edge (bb, dest);
3922 /* Perform the redirection. */
3925 e = redirect_edge_and_branch (e, dest);
3927 /* Update the profile. */
3928 if (profile_status != PROFILE_ABSENT)
3929 for (curr = old_dest; curr != dest; curr = EDGE_SUCC (curr, 0)->dest)
3931 curr->frequency -= freq;
3932 if (curr->frequency < 0)
3933 curr->frequency = 0;
3934 curr->count -= count;
3935 if (curr->count < 0)
3937 EDGE_SUCC (curr, 0)->count -= count;
3938 if (EDGE_SUCC (curr, 0)->count < 0)
3939 EDGE_SUCC (curr, 0)->count = 0;
3944 /* Update PHI nodes. We know that the new argument should
3945 have the same value as the argument associated with LAST.
3946 Otherwise we would have changed our target block above. */
3947 for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi))
3949 arg = phi_arg_from_edge (phi, last);
3950 gcc_assert (arg >= 0);
3951 add_phi_arg (&phi, PHI_ARG_DEF (phi, arg), e);
3955 /* Update the dominators. */
3956 if (dom_computed[CDI_DOMINATORS] >= DOM_CONS_OK)
3958 /* Remove the unreachable blocks (observe that if all blocks
3959 were reachable before, only those in the path we threaded
3960 over and did not have any predecessor outside of the path
3961 become unreachable). */
3962 for (; old_dest != dest; old_dest = tmp)
3964 tmp = EDGE_SUCC (old_dest, 0)->dest;
3966 if (EDGE_COUNT (old_dest->preds) > 0)
3969 delete_basic_block (old_dest);
3971 /* If the dominator of the destination was in the path, set its
3972 dominator to the start of the redirected edge. */
3973 if (get_immediate_dominator (CDI_DOMINATORS, old_dest) == NULL)
3974 set_immediate_dominator (CDI_DOMINATORS, old_dest, bb);
3976 /* Now proceed like if we forwarded just over one edge at a time.
3977 Algorithm for forwarding edge S --> A over edge A --> B then
3981 && !dominated_by (S, B))
3982 idom (B) = idom (A);
3983 recount_idom (A); */
3985 for (; old_dest != dest; old_dest = tmp)
3987 tmp = EDGE_SUCC (old_dest, 0)->dest;
3989 if (get_immediate_dominator (CDI_DOMINATORS, tmp) == old_dest
3990 && !dominated_by_p (CDI_DOMINATORS, bb, tmp))
3992 dom = get_immediate_dominator (CDI_DOMINATORS, old_dest);
3993 set_immediate_dominator (CDI_DOMINATORS, tmp, dom);
3996 dom = recount_dominator (CDI_DOMINATORS, old_dest);
3997 set_immediate_dominator (CDI_DOMINATORS, old_dest, dom);
4002 /* Reset the forwardable bit on our block since it's no longer in
4003 a forwarding chain path. */
4004 bb_ann (bb)->forwardable = 1;
4011 /* Return a non-special label in the head of basic block BLOCK.
4012 Create one if it doesn't exist. */
4015 tree_block_label (basic_block bb)
4017 block_stmt_iterator i, s = bsi_start (bb);
4021 for (i = s; !bsi_end_p (i); first = false, bsi_next (&i))
4023 stmt = bsi_stmt (i);
4024 if (TREE_CODE (stmt) != LABEL_EXPR)
4026 label = LABEL_EXPR_LABEL (stmt);
4027 if (!DECL_NONLOCAL (label))
4030 bsi_move_before (&i, &s);
4035 label = create_artificial_label ();
4036 stmt = build1 (LABEL_EXPR, void_type_node, label);
4037 bsi_insert_before (&s, stmt, BSI_NEW_STMT);
4042 /* Attempt to perform edge redirection by replacing a possibly complex
4043 jump instruction by a goto or by removing the jump completely.
4044 This can apply only if all edges now point to the same block. The
4045 parameters and return values are equivalent to
4046 redirect_edge_and_branch. */
4049 tree_try_redirect_by_replacing_jump (edge e, basic_block target)
4051 basic_block src = e->src;
4053 block_stmt_iterator b;
4057 /* Verify that all targets will be TARGET. */
4058 FOR_EACH_EDGE (tmp, ei, src->succs)
4059 if (tmp->dest != target && tmp != e)
4068 stmt = bsi_stmt (b);
4070 if (TREE_CODE (stmt) == COND_EXPR
4071 || TREE_CODE (stmt) == SWITCH_EXPR)
4074 e = ssa_redirect_edge (e, target);
4075 e->flags = EDGE_FALLTHRU;
4083 /* Redirect E to DEST. Return NULL on failure. Otherwise, return the
4084 edge representing the redirected branch. */
4087 tree_redirect_edge_and_branch (edge e, basic_block dest)
4089 basic_block bb = e->src;
4090 block_stmt_iterator bsi;
4094 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
4097 if (e->src != ENTRY_BLOCK_PTR
4098 && (ret = tree_try_redirect_by_replacing_jump (e, dest)))
4101 if (e->dest == dest)
4104 label = tree_block_label (dest);
4106 bsi = bsi_last (bb);
4107 stmt = bsi_end_p (bsi) ? NULL : bsi_stmt (bsi);
4109 switch (stmt ? TREE_CODE (stmt) : ERROR_MARK)
4112 stmt = (e->flags & EDGE_TRUE_VALUE
4113 ? COND_EXPR_THEN (stmt)
4114 : COND_EXPR_ELSE (stmt));
4115 GOTO_DESTINATION (stmt) = label;
4119 /* No non-abnormal edges should lead from a non-simple goto, and
4120 simple ones should be represented implicitly. */
4125 tree vec = SWITCH_LABELS (stmt);
4126 size_t i, n = TREE_VEC_LENGTH (vec);
4128 for (i = 0; i < n; ++i)
4130 tree elt = TREE_VEC_ELT (vec, i);
4131 if (label_to_block (CASE_LABEL (elt)) == e->dest)
4132 CASE_LABEL (elt) = label;
4139 e->flags |= EDGE_FALLTHRU;
4143 /* Otherwise it must be a fallthru edge, and we don't need to
4144 do anything besides redirecting it. */
4145 gcc_assert (e->flags & EDGE_FALLTHRU);
4149 /* Update/insert PHI nodes as necessary. */
4151 /* Now update the edges in the CFG. */
4152 e = ssa_redirect_edge (e, dest);
4158 /* Simple wrapper, as we can always redirect fallthru edges. */
4161 tree_redirect_edge_and_branch_force (edge e, basic_block dest)
4163 e = tree_redirect_edge_and_branch (e, dest);
4170 /* Splits basic block BB after statement STMT (but at least after the
4171 labels). If STMT is NULL, BB is split just after the labels. */
4174 tree_split_block (basic_block bb, void *stmt)
4176 block_stmt_iterator bsi, bsi_tgt;
4182 new_bb = create_empty_bb (bb);
4184 /* Redirect the outgoing edges. */
4185 new_bb->succs = bb->succs;
4187 FOR_EACH_EDGE (e, ei, new_bb->succs)
4190 if (stmt && TREE_CODE ((tree) stmt) == LABEL_EXPR)
4193 /* Move everything from BSI to the new basic block. */
4194 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4196 act = bsi_stmt (bsi);
4197 if (TREE_CODE (act) == LABEL_EXPR)
4210 bsi_tgt = bsi_start (new_bb);
4211 while (!bsi_end_p (bsi))
4213 act = bsi_stmt (bsi);
4215 bsi_insert_after (&bsi_tgt, act, BSI_NEW_STMT);
4222 /* Moves basic block BB after block AFTER. */
4225 tree_move_block_after (basic_block bb, basic_block after)
4227 if (bb->prev_bb == after)
4231 link_block (bb, after);
4237 /* Return true if basic_block can be duplicated. */
4240 tree_can_duplicate_bb_p (basic_block bb ATTRIBUTE_UNUSED)
4245 /* Create a duplicate of the basic block BB. NOTE: This does not
4246 preserve SSA form. */
4249 tree_duplicate_bb (basic_block bb)
4252 block_stmt_iterator bsi, bsi_tgt;
4254 ssa_op_iter op_iter;
4256 new_bb = create_empty_bb (EXIT_BLOCK_PTR->prev_bb);
4258 /* First copy the phi nodes. We do not copy phi node arguments here,
4259 since the edges are not ready yet. Keep the chain of phi nodes in
4260 the same order, so that we can add them later. */
4261 for (phi = phi_nodes (bb); phi; phi = TREE_CHAIN (phi))
4263 mark_for_rewrite (PHI_RESULT (phi));
4264 create_phi_node (PHI_RESULT (phi), new_bb);
4266 set_phi_nodes (new_bb, nreverse (phi_nodes (new_bb)));
4268 bsi_tgt = bsi_start (new_bb);
4269 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4271 tree stmt = bsi_stmt (bsi);
4274 if (TREE_CODE (stmt) == LABEL_EXPR)
4277 /* Record the definitions. */
4278 get_stmt_operands (stmt);
4280 FOR_EACH_SSA_TREE_OPERAND (val, stmt, op_iter, SSA_OP_ALL_DEFS)
4281 mark_for_rewrite (val);
4283 copy = unshare_expr (stmt);
4285 /* Copy also the virtual operands. */
4286 get_stmt_ann (copy);
4287 copy_virtual_operands (copy, stmt);
4289 bsi_insert_after (&bsi_tgt, copy, BSI_NEW_STMT);
4295 /* Basic block BB_COPY was created by code duplication. Add phi node
4296 arguments for edges going out of BB_COPY. The blocks that were
4297 duplicated have rbi->duplicated set to one. */
4300 add_phi_args_after_copy_bb (basic_block bb_copy)
4302 basic_block bb, dest;
4305 tree phi, phi_copy, phi_next, def;
4307 bb = bb_copy->rbi->original;
4309 FOR_EACH_EDGE (e_copy, ei, bb_copy->succs)
4311 if (!phi_nodes (e_copy->dest))
4314 if (e_copy->dest->rbi->duplicated)
4315 dest = e_copy->dest->rbi->original;
4317 dest = e_copy->dest;
4319 e = find_edge (bb, dest);
4322 /* During loop unrolling the target of the latch edge is copied.
4323 In this case we are not looking for edge to dest, but to
4324 duplicated block whose original was dest. */
4325 FOR_EACH_EDGE (e, ei, bb->succs)
4326 if (e->dest->rbi->duplicated
4327 && e->dest->rbi->original == dest)
4330 gcc_assert (e != NULL);
4333 for (phi = phi_nodes (e->dest), phi_copy = phi_nodes (e_copy->dest);
4335 phi = phi_next, phi_copy = TREE_CHAIN (phi_copy))
4337 phi_next = TREE_CHAIN (phi);
4339 gcc_assert (PHI_RESULT (phi) == PHI_RESULT (phi_copy));
4340 def = PHI_ARG_DEF_FROM_EDGE (phi, e);
4341 add_phi_arg (&phi_copy, def, e_copy);
4346 /* Blocks in REGION_COPY array of length N_REGION were created by
4347 duplication of basic blocks. Add phi node arguments for edges
4348 going from these blocks. */
4351 add_phi_args_after_copy (basic_block *region_copy, unsigned n_region)
4355 for (i = 0; i < n_region; i++)
4356 region_copy[i]->rbi->duplicated = 1;
4358 for (i = 0; i < n_region; i++)
4359 add_phi_args_after_copy_bb (region_copy[i]);
4361 for (i = 0; i < n_region; i++)
4362 region_copy[i]->rbi->duplicated = 0;
4365 /* Maps the old ssa name FROM_NAME to TO_NAME. */
4367 struct ssa_name_map_entry
4373 /* Hash function for ssa_name_map_entry. */
4376 ssa_name_map_entry_hash (const void *entry)
4378 const struct ssa_name_map_entry *en = entry;
4379 return SSA_NAME_VERSION (en->from_name);
4382 /* Equality function for ssa_name_map_entry. */
4385 ssa_name_map_entry_eq (const void *in_table, const void *ssa_name)
4387 const struct ssa_name_map_entry *en = in_table;
4389 return en->from_name == ssa_name;
4392 /* Allocate duplicates of ssa names in list DEFINITIONS and store the mapping
4396 allocate_ssa_names (bitmap definitions, htab_t *map)
4399 struct ssa_name_map_entry *entry;
4405 *map = htab_create (10, ssa_name_map_entry_hash,
4406 ssa_name_map_entry_eq, free);
4407 EXECUTE_IF_SET_IN_BITMAP (definitions, 0, ver, bi)
4409 name = ssa_name (ver);
4410 slot = htab_find_slot_with_hash (*map, name, SSA_NAME_VERSION (name),
4416 entry = xmalloc (sizeof (struct ssa_name_map_entry));
4417 entry->from_name = name;
4420 entry->to_name = duplicate_ssa_name (name, SSA_NAME_DEF_STMT (name));
4424 /* Rewrite the definition DEF in statement STMT to new ssa name as specified
4425 by the mapping MAP. */
4428 rewrite_to_new_ssa_names_def (def_operand_p def, tree stmt, htab_t map)
4430 tree name = DEF_FROM_PTR (def);
4431 struct ssa_name_map_entry *entry;
4433 gcc_assert (TREE_CODE (name) == SSA_NAME);
4435 entry = htab_find_with_hash (map, name, SSA_NAME_VERSION (name));
4439 SET_DEF (def, entry->to_name);
4440 SSA_NAME_DEF_STMT (entry->to_name) = stmt;
4443 /* Rewrite the USE to new ssa name as specified by the mapping MAP. */
4446 rewrite_to_new_ssa_names_use (use_operand_p use, htab_t map)
4448 tree name = USE_FROM_PTR (use);
4449 struct ssa_name_map_entry *entry;
4451 if (TREE_CODE (name) != SSA_NAME)
4454 entry = htab_find_with_hash (map, name, SSA_NAME_VERSION (name));
4458 SET_USE (use, entry->to_name);
4461 /* Rewrite the ssa names in basic block BB to new ones as specified by the
4465 rewrite_to_new_ssa_names_bb (basic_block bb, htab_t map)
4471 block_stmt_iterator bsi;
4475 v_may_def_optype v_may_defs;
4476 v_must_def_optype v_must_defs;
4479 FOR_EACH_EDGE (e, ei, bb->preds)
4480 if (e->flags & EDGE_ABNORMAL)
4483 for (phi = phi_nodes (bb); phi; phi = TREE_CHAIN (phi))
4485 rewrite_to_new_ssa_names_def (PHI_RESULT_PTR (phi), phi, map);
4487 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (PHI_RESULT (phi)) = 1;
4490 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4492 stmt = bsi_stmt (bsi);
4493 get_stmt_operands (stmt);
4494 ann = stmt_ann (stmt);
4496 uses = USE_OPS (ann);
4497 for (i = 0; i < NUM_USES (uses); i++)
4498 rewrite_to_new_ssa_names_use (USE_OP_PTR (uses, i), map);
4500 defs = DEF_OPS (ann);
4501 for (i = 0; i < NUM_DEFS (defs); i++)
4502 rewrite_to_new_ssa_names_def (DEF_OP_PTR (defs, i), stmt, map);
4504 vuses = VUSE_OPS (ann);
4505 for (i = 0; i < NUM_VUSES (vuses); i++)
4506 rewrite_to_new_ssa_names_use (VUSE_OP_PTR (vuses, i), map);
4508 v_may_defs = V_MAY_DEF_OPS (ann);
4509 for (i = 0; i < NUM_V_MAY_DEFS (v_may_defs); i++)
4511 rewrite_to_new_ssa_names_use
4512 (V_MAY_DEF_OP_PTR (v_may_defs, i), map);
4513 rewrite_to_new_ssa_names_def
4514 (V_MAY_DEF_RESULT_PTR (v_may_defs, i), stmt, map);
4517 v_must_defs = V_MUST_DEF_OPS (ann);
4518 for (i = 0; i < NUM_V_MUST_DEFS (v_must_defs); i++)
4519 rewrite_to_new_ssa_names_def
4520 (V_MUST_DEF_OP_PTR (v_must_defs, i), stmt, map);
4523 FOR_EACH_EDGE (e, ei, bb->succs)
4524 for (phi = phi_nodes (e->dest); phi; phi = TREE_CHAIN (phi))
4526 rewrite_to_new_ssa_names_use
4527 (PHI_ARG_DEF_PTR_FROM_EDGE (phi, e), map);
4529 if (e->flags & EDGE_ABNORMAL)
4531 tree op = PHI_ARG_DEF_FROM_EDGE (phi, e);
4532 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op) = 1;
4537 /* Rewrite the ssa names in N_REGION blocks REGION to the new ones as specified
4538 by the mapping MAP. */
4541 rewrite_to_new_ssa_names (basic_block *region, unsigned n_region, htab_t map)
4545 for (r = 0; r < n_region; r++)
4546 rewrite_to_new_ssa_names_bb (region[r], map);
4549 /* Duplicates a REGION (set of N_REGION basic blocks) with just a single
4550 important exit edge EXIT. By important we mean that no SSA name defined
4551 inside region is live over the other exit edges of the region. All entry
4552 edges to the region must go to ENTRY->dest. The edge ENTRY is redirected
4553 to the duplicate of the region. SSA form, dominance and loop information
4554 is updated. The new basic blocks are stored to REGION_COPY in the same
4555 order as they had in REGION, provided that REGION_COPY is not NULL.
4556 The function returns false if it is unable to copy the region,
4560 tree_duplicate_sese_region (edge entry, edge exit,
4561 basic_block *region, unsigned n_region,
4562 basic_block *region_copy)
4564 unsigned i, n_doms, ver;
4565 bool free_region_copy = false, copying_header = false;
4566 struct loop *loop = entry->dest->loop_father;
4571 htab_t ssa_name_map = NULL;
4575 if (!can_copy_bbs_p (region, n_region))
4578 /* Some sanity checking. Note that we do not check for all possible
4579 missuses of the functions. I.e. if you ask to copy something weird,
4580 it will work, but the state of structures probably will not be
4583 for (i = 0; i < n_region; i++)
4585 /* We do not handle subloops, i.e. all the blocks must belong to the
4587 if (region[i]->loop_father != loop)
4590 if (region[i] != entry->dest
4591 && region[i] == loop->header)
4597 /* In case the function is used for loop header copying (which is the primary
4598 use), ensure that EXIT and its copy will be new latch and entry edges. */
4599 if (loop->header == entry->dest)
4601 copying_header = true;
4602 loop->copy = loop->outer;
4604 if (!dominated_by_p (CDI_DOMINATORS, loop->latch, exit->src))
4607 for (i = 0; i < n_region; i++)
4608 if (region[i] != exit->src
4609 && dominated_by_p (CDI_DOMINATORS, region[i], exit->src))
4615 region_copy = xmalloc (sizeof (basic_block) * n_region);
4616 free_region_copy = true;
4619 gcc_assert (!any_marked_for_rewrite_p ());
4621 /* Record blocks outside the region that are duplicated by something
4623 doms = xmalloc (sizeof (basic_block) * n_basic_blocks);
4624 n_doms = get_dominated_by_region (CDI_DOMINATORS, region, n_region, doms);
4626 copy_bbs (region, n_region, region_copy, &exit, 1, &exit_copy, loop);
4627 definitions = marked_ssa_names ();
4631 loop->header = exit->dest;
4632 loop->latch = exit->src;
4635 /* Redirect the entry and add the phi node arguments. */
4636 redirected = redirect_edge_and_branch (entry, entry->dest->rbi->copy);
4637 gcc_assert (redirected != NULL);
4638 for (phi = phi_nodes (entry->dest), var = PENDING_STMT (entry);
4640 phi = TREE_CHAIN (phi), var = TREE_CHAIN (var))
4641 add_phi_arg (&phi, TREE_VALUE (var), entry);
4642 PENDING_STMT (entry) = NULL;
4644 /* Concerning updating of dominators: We must recount dominators
4645 for entry block and its copy. Anything that is outside of the region, but
4646 was dominated by something inside needs recounting as well. */
4647 set_immediate_dominator (CDI_DOMINATORS, entry->dest, entry->src);
4648 doms[n_doms++] = entry->dest->rbi->original;
4649 iterate_fix_dominators (CDI_DOMINATORS, doms, n_doms);
4652 /* Add the other phi node arguments. */
4653 add_phi_args_after_copy (region_copy, n_region);
4655 /* Add phi nodes for definitions at exit. TODO -- once we have immediate
4656 uses, it should be possible to emit phi nodes just for definitions that
4657 are used outside region. */
4658 EXECUTE_IF_SET_IN_BITMAP (definitions, 0, ver, bi)
4660 tree name = ssa_name (ver);
4662 phi = create_phi_node (name, exit->dest);
4663 add_phi_arg (&phi, name, exit);
4664 add_phi_arg (&phi, name, exit_copy);
4666 SSA_NAME_DEF_STMT (name) = phi;
4669 /* And create new definitions inside region and its copy. TODO -- once we
4670 have immediate uses, it might be better to leave definitions in region
4671 unchanged, create new ssa names for phi nodes on exit, and rewrite
4672 the uses, to avoid changing the copied region. */
4673 allocate_ssa_names (definitions, &ssa_name_map);
4674 rewrite_to_new_ssa_names (region, n_region, ssa_name_map);
4675 allocate_ssa_names (definitions, &ssa_name_map);
4676 rewrite_to_new_ssa_names (region_copy, n_region, ssa_name_map);
4677 htab_delete (ssa_name_map);
4679 if (free_region_copy)
4682 unmark_all_for_rewrite ();
4683 BITMAP_XFREE (definitions);
4688 /* Dump FUNCTION_DECL FN to file FILE using FLAGS (see TDF_* in tree.h) */
4691 dump_function_to_file (tree fn, FILE *file, int flags)
4693 tree arg, vars, var;
4694 bool ignore_topmost_bind = false, any_var = false;
4698 fprintf (file, "%s (", lang_hooks.decl_printable_name (fn, 2));
4700 arg = DECL_ARGUMENTS (fn);
4703 print_generic_expr (file, arg, dump_flags);
4704 if (TREE_CHAIN (arg))
4705 fprintf (file, ", ");
4706 arg = TREE_CHAIN (arg);
4708 fprintf (file, ")\n");
4710 if (flags & TDF_RAW)
4712 dump_node (fn, TDF_SLIM | flags, file);
4716 /* When GIMPLE is lowered, the variables are no longer available in
4717 BIND_EXPRs, so display them separately. */
4718 if (cfun && cfun->unexpanded_var_list)
4720 ignore_topmost_bind = true;
4722 fprintf (file, "{\n");
4723 for (vars = cfun->unexpanded_var_list; vars; vars = TREE_CHAIN (vars))
4725 var = TREE_VALUE (vars);
4727 print_generic_decl (file, var, flags);
4728 fprintf (file, "\n");
4734 if (basic_block_info)
4736 /* Make a CFG based dump. */
4737 check_bb_profile (ENTRY_BLOCK_PTR, file);
4738 if (!ignore_topmost_bind)
4739 fprintf (file, "{\n");
4741 if (any_var && n_basic_blocks)
4742 fprintf (file, "\n");
4745 dump_generic_bb (file, bb, 2, flags);
4747 fprintf (file, "}\n");
4748 check_bb_profile (EXIT_BLOCK_PTR, file);
4754 /* Make a tree based dump. */
4755 chain = DECL_SAVED_TREE (fn);
4757 if (TREE_CODE (chain) == BIND_EXPR)
4759 if (ignore_topmost_bind)
4761 chain = BIND_EXPR_BODY (chain);
4769 if (!ignore_topmost_bind)
4770 fprintf (file, "{\n");
4775 fprintf (file, "\n");
4777 print_generic_stmt_indented (file, chain, flags, indent);
4778 if (ignore_topmost_bind)
4779 fprintf (file, "}\n");
4782 fprintf (file, "\n\n");
4786 /* Pretty print of the loops intermediate representation. */
4787 static void print_loop (FILE *, struct loop *, int);
4788 static void print_pred_bbs (FILE *, basic_block bb);
4789 static void print_succ_bbs (FILE *, basic_block bb);
4792 /* Print the predecessors indexes of edge E on FILE. */
4795 print_pred_bbs (FILE *file, basic_block bb)
4800 FOR_EACH_EDGE (e, ei, bb->preds)
4801 fprintf (file, "bb_%d", e->src->index);
4805 /* Print the successors indexes of edge E on FILE. */
4808 print_succ_bbs (FILE *file, basic_block bb)
4813 FOR_EACH_EDGE (e, ei, bb->succs)
4814 fprintf (file, "bb_%d", e->src->index);
4818 /* Pretty print LOOP on FILE, indented INDENT spaces. */
4821 print_loop (FILE *file, struct loop *loop, int indent)
4829 s_indent = (char *) alloca ((size_t) indent + 1);
4830 memset ((void *) s_indent, ' ', (size_t) indent);
4831 s_indent[indent] = '\0';
4833 /* Print the loop's header. */
4834 fprintf (file, "%sloop_%d\n", s_indent, loop->num);
4836 /* Print the loop's body. */
4837 fprintf (file, "%s{\n", s_indent);
4839 if (bb->loop_father == loop)
4841 /* Print the basic_block's header. */
4842 fprintf (file, "%s bb_%d (preds = {", s_indent, bb->index);
4843 print_pred_bbs (file, bb);
4844 fprintf (file, "}, succs = {");
4845 print_succ_bbs (file, bb);
4846 fprintf (file, "})\n");
4848 /* Print the basic_block's body. */
4849 fprintf (file, "%s {\n", s_indent);
4850 tree_dump_bb (bb, file, indent + 4);
4851 fprintf (file, "%s }\n", s_indent);
4854 print_loop (file, loop->inner, indent + 2);
4855 fprintf (file, "%s}\n", s_indent);
4856 print_loop (file, loop->next, indent);
4860 /* Follow a CFG edge from the entry point of the program, and on entry
4861 of a loop, pretty print the loop structure on FILE. */
4864 print_loop_ir (FILE *file)
4868 bb = BASIC_BLOCK (0);
4869 if (bb && bb->loop_father)
4870 print_loop (file, bb->loop_father, 0);
4874 /* Debugging loops structure at tree level. */
4877 debug_loop_ir (void)
4879 print_loop_ir (stderr);
4883 /* Return true if BB ends with a call, possibly followed by some
4884 instructions that must stay with the call. Return false,
4888 tree_block_ends_with_call_p (basic_block bb)
4890 block_stmt_iterator bsi = bsi_last (bb);
4891 return get_call_expr_in (bsi_stmt (bsi)) != NULL;
4895 /* Return true if BB ends with a conditional branch. Return false,
4899 tree_block_ends_with_condjump_p (basic_block bb)
4901 tree stmt = tsi_stmt (bsi_last (bb).tsi);
4902 return (TREE_CODE (stmt) == COND_EXPR);
4906 /* Return true if we need to add fake edge to exit at statement T.
4907 Helper function for tree_flow_call_edges_add. */
4910 need_fake_edge_p (tree t)
4914 /* NORETURN and LONGJMP calls already have an edge to exit.
4915 CONST, PURE and ALWAYS_RETURN calls do not need one.
4916 We don't currently check for CONST and PURE here, although
4917 it would be a good idea, because those attributes are
4918 figured out from the RTL in mark_constant_function, and
4919 the counter incrementation code from -fprofile-arcs
4920 leads to different results from -fbranch-probabilities. */
4921 call = get_call_expr_in (t);
4923 && !(call_expr_flags (call) &
4924 (ECF_NORETURN | ECF_LONGJMP | ECF_ALWAYS_RETURN)))
4927 if (TREE_CODE (t) == ASM_EXPR
4928 && (ASM_VOLATILE_P (t) || ASM_INPUT_P (t)))
4935 /* Add fake edges to the function exit for any non constant and non
4936 noreturn calls, volatile inline assembly in the bitmap of blocks
4937 specified by BLOCKS or to the whole CFG if BLOCKS is zero. Return
4938 the number of blocks that were split.
4940 The goal is to expose cases in which entering a basic block does
4941 not imply that all subsequent instructions must be executed. */
4944 tree_flow_call_edges_add (sbitmap blocks)
4947 int blocks_split = 0;
4948 int last_bb = last_basic_block;
4949 bool check_last_block = false;
4951 if (n_basic_blocks == 0)
4955 check_last_block = true;
4957 check_last_block = TEST_BIT (blocks, EXIT_BLOCK_PTR->prev_bb->index);
4959 /* In the last basic block, before epilogue generation, there will be
4960 a fallthru edge to EXIT. Special care is required if the last insn
4961 of the last basic block is a call because make_edge folds duplicate
4962 edges, which would result in the fallthru edge also being marked
4963 fake, which would result in the fallthru edge being removed by
4964 remove_fake_edges, which would result in an invalid CFG.
4966 Moreover, we can't elide the outgoing fake edge, since the block
4967 profiler needs to take this into account in order to solve the minimal
4968 spanning tree in the case that the call doesn't return.
4970 Handle this by adding a dummy instruction in a new last basic block. */
4971 if (check_last_block)
4974 basic_block bb = EXIT_BLOCK_PTR->prev_bb;
4975 block_stmt_iterator bsi = bsi_last (bb);
4977 if (!bsi_end_p (bsi))
4980 if (need_fake_edge_p (t))
4984 FOR_EACH_EDGE (e, ei, bb->succs)
4985 if (e->dest == EXIT_BLOCK_PTR)
4987 bsi_insert_on_edge (e, build_empty_stmt ());
4988 bsi_commit_edge_inserts ((int *)NULL);
4994 /* Now add fake edges to the function exit for any non constant
4995 calls since there is no way that we can determine if they will
4997 for (i = 0; i < last_bb; i++)
4999 basic_block bb = BASIC_BLOCK (i);
5000 block_stmt_iterator bsi;
5001 tree stmt, last_stmt;
5006 if (blocks && !TEST_BIT (blocks, i))
5009 bsi = bsi_last (bb);
5010 if (!bsi_end_p (bsi))
5012 last_stmt = bsi_stmt (bsi);
5015 stmt = bsi_stmt (bsi);
5016 if (need_fake_edge_p (stmt))
5019 /* The handling above of the final block before the
5020 epilogue should be enough to verify that there is
5021 no edge to the exit block in CFG already.
5022 Calling make_edge in such case would cause us to
5023 mark that edge as fake and remove it later. */
5024 #ifdef ENABLE_CHECKING
5025 if (stmt == last_stmt)
5028 FOR_EACH_EDGE (e, ei, bb->succs)
5029 gcc_assert (e->dest != EXIT_BLOCK_PTR);
5033 /* Note that the following may create a new basic block
5034 and renumber the existing basic blocks. */
5035 if (stmt != last_stmt)
5037 e = split_block (bb, stmt);
5041 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
5045 while (!bsi_end_p (bsi));
5050 verify_flow_info ();
5052 return blocks_split;
5056 tree_purge_dead_eh_edges (basic_block bb)
5058 bool changed = false;
5061 tree stmt = last_stmt (bb);
5063 if (stmt && tree_can_throw_internal (stmt))
5066 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
5068 if (e->flags & EDGE_EH)
5070 ssa_remove_edge (e);
5081 tree_purge_all_dead_eh_edges (bitmap blocks)
5083 bool changed = false;
5087 EXECUTE_IF_SET_IN_BITMAP (blocks, 0, i, bi)
5089 changed |= tree_purge_dead_eh_edges (BASIC_BLOCK (i));
5095 struct cfg_hooks tree_cfg_hooks = {
5097 tree_verify_flow_info,
5098 tree_dump_bb, /* dump_bb */
5099 create_bb, /* create_basic_block */
5100 tree_redirect_edge_and_branch,/* redirect_edge_and_branch */
5101 tree_redirect_edge_and_branch_force,/* redirect_edge_and_branch_force */
5102 remove_bb, /* delete_basic_block */
5103 tree_split_block, /* split_block */
5104 tree_move_block_after, /* move_block_after */
5105 tree_can_merge_blocks_p, /* can_merge_blocks_p */
5106 tree_merge_blocks, /* merge_blocks */
5107 tree_predict_edge, /* predict_edge */
5108 tree_predicted_by_p, /* predicted_by_p */
5109 tree_can_duplicate_bb_p, /* can_duplicate_block_p */
5110 tree_duplicate_bb, /* duplicate_block */
5111 tree_split_edge, /* split_edge */
5112 tree_make_forwarder_block, /* make_forward_block */
5113 NULL, /* tidy_fallthru_edge */
5114 tree_block_ends_with_call_p, /* block_ends_with_call_p */
5115 tree_block_ends_with_condjump_p, /* block_ends_with_condjump_p */
5116 tree_flow_call_edges_add /* flow_call_edges_add */
5120 /* Split all critical edges. */
5123 split_critical_edges (void)
5131 FOR_EACH_EDGE (e, ei, bb->succs)
5132 if (EDGE_CRITICAL_P (e) && !(e->flags & EDGE_ABNORMAL))
5139 struct tree_opt_pass pass_split_crit_edges =
5141 "crited", /* name */
5143 split_critical_edges, /* execute */
5146 0, /* static_pass_number */
5147 TV_TREE_SPLIT_EDGES, /* tv_id */
5148 PROP_cfg, /* properties required */
5149 PROP_no_crit_edges, /* properties_provided */
5150 0, /* properties_destroyed */
5151 0, /* todo_flags_start */
5152 TODO_dump_func, /* todo_flags_finish */
5157 /* Return EXP if it is a valid GIMPLE rvalue, else gimplify it into
5158 a temporary, make sure and register it to be renamed if necessary,
5159 and finally return the temporary. Put the statements to compute
5160 EXP before the current statement in BSI. */
5163 gimplify_val (block_stmt_iterator *bsi, tree type, tree exp)
5165 tree t, new_stmt, orig_stmt;
5167 if (is_gimple_val (exp))
5170 t = make_rename_temp (type, NULL);
5171 new_stmt = build (MODIFY_EXPR, type, t, exp);
5173 orig_stmt = bsi_stmt (*bsi);
5174 SET_EXPR_LOCUS (new_stmt, EXPR_LOCUS (orig_stmt));
5175 TREE_BLOCK (new_stmt) = TREE_BLOCK (orig_stmt);
5177 bsi_insert_before (bsi, new_stmt, BSI_SAME_STMT);
5182 /* Build a ternary operation and gimplify it. Emit code before BSI.
5183 Return the gimple_val holding the result. */
5186 gimplify_build3 (block_stmt_iterator *bsi, enum tree_code code,
5187 tree type, tree a, tree b, tree c)
5191 ret = fold (build3 (code, type, a, b, c));
5194 return gimplify_val (bsi, type, ret);
5197 /* Build a binary operation and gimplify it. Emit code before BSI.
5198 Return the gimple_val holding the result. */
5201 gimplify_build2 (block_stmt_iterator *bsi, enum tree_code code,
5202 tree type, tree a, tree b)
5206 ret = fold (build2 (code, type, a, b));
5209 return gimplify_val (bsi, type, ret);
5212 /* Build a unary operation and gimplify it. Emit code before BSI.
5213 Return the gimple_val holding the result. */
5216 gimplify_build1 (block_stmt_iterator *bsi, enum tree_code code, tree type,
5221 ret = fold (build1 (code, type, a));
5224 return gimplify_val (bsi, type, ret);
5229 /* Emit return warnings. */
5232 execute_warn_function_return (void)
5234 #ifdef USE_MAPPED_LOCATION
5235 source_location location;
5243 if (warn_missing_noreturn
5244 && !TREE_THIS_VOLATILE (cfun->decl)
5245 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) == 0
5246 && !lang_hooks.function.missing_noreturn_ok_p (cfun->decl))
5247 warning ("%Jfunction might be possible candidate for "
5248 "attribute %<noreturn%>",
5251 /* If we have a path to EXIT, then we do return. */
5252 if (TREE_THIS_VOLATILE (cfun->decl)
5253 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) > 0)
5255 #ifdef USE_MAPPED_LOCATION
5256 location = UNKNOWN_LOCATION;
5260 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
5262 last = last_stmt (e->src);
5263 if (TREE_CODE (last) == RETURN_EXPR
5264 #ifdef USE_MAPPED_LOCATION
5265 && (location = EXPR_LOCATION (last)) != UNKNOWN_LOCATION)
5267 && (locus = EXPR_LOCUS (last)) != NULL)
5271 #ifdef USE_MAPPED_LOCATION
5272 if (location == UNKNOWN_LOCATION)
5273 location = cfun->function_end_locus;
5274 warning ("%H%<noreturn%> function does return", &location);
5277 locus = &cfun->function_end_locus;
5278 warning ("%H%<noreturn%> function does return", locus);
5282 /* If we see "return;" in some basic block, then we do reach the end
5283 without returning a value. */
5284 else if (warn_return_type
5285 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) > 0
5286 && !VOID_TYPE_P (TREE_TYPE (TREE_TYPE (cfun->decl))))
5288 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
5290 tree last = last_stmt (e->src);
5291 if (TREE_CODE (last) == RETURN_EXPR
5292 && TREE_OPERAND (last, 0) == NULL)
5294 #ifdef USE_MAPPED_LOCATION
5295 location = EXPR_LOCATION (last);
5296 if (location == UNKNOWN_LOCATION)
5297 location = cfun->function_end_locus;
5298 warning ("%Hcontrol reaches end of non-void function", &location);
5300 locus = EXPR_LOCUS (last);
5302 locus = &cfun->function_end_locus;
5303 warning ("%Hcontrol reaches end of non-void function", locus);
5312 /* Given a basic block B which ends with a conditional and has
5313 precisely two successors, determine which of the edges is taken if
5314 the conditional is true and which is taken if the conditional is
5315 false. Set TRUE_EDGE and FALSE_EDGE appropriately. */
5318 extract_true_false_edges_from_block (basic_block b,
5322 edge e = EDGE_SUCC (b, 0);
5324 if (e->flags & EDGE_TRUE_VALUE)
5327 *false_edge = EDGE_SUCC (b, 1);
5332 *true_edge = EDGE_SUCC (b, 1);
5336 struct tree_opt_pass pass_warn_function_return =
5340 execute_warn_function_return, /* execute */
5343 0, /* static_pass_number */
5345 PROP_cfg, /* properties_required */
5346 0, /* properties_provided */
5347 0, /* properties_destroyed */
5348 0, /* todo_flags_start */
5349 0, /* todo_flags_finish */
5353 #include "gt-tree-cfg.h"