1 /* Control flow functions for trees.
2 Copyright (C) 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
3 Contributed by Diego Novillo <dnovillo@redhat.com>
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 GCC is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to
19 the Free Software Foundation, 59 Temple Place - Suite 330,
20 Boston, MA 02111-1307, USA. */
24 #include "coretypes.h"
29 #include "hard-reg-set.h"
30 #include "basic-block.h"
37 #include "langhooks.h"
38 #include "diagnostic.h"
39 #include "tree-flow.h"
41 #include "tree-dump.h"
42 #include "tree-pass.h"
46 #include "cfglayout.h"
48 /* This file contains functions for building the Control Flow Graph (CFG)
49 for a function tree. */
51 /* Local declarations. */
53 /* Initial capacity for the basic block array. */
54 static const int initial_cfg_capacity = 20;
56 /* Mapping of labels to their associated blocks. This can greatly speed up
57 building of the CFG in code with lots of gotos. */
58 static GTY(()) varray_type label_to_block_map;
63 long num_merged_labels;
66 static struct cfg_stats_d cfg_stats;
68 /* Nonzero if we found a computed goto while building basic blocks. */
69 static bool found_computed_goto;
71 /* Basic blocks and flowgraphs. */
72 static basic_block create_bb (void *, void *, basic_block);
73 static void create_block_annotation (basic_block);
74 static void free_blocks_annotations (void);
75 static void clear_blocks_annotations (void);
76 static void make_blocks (tree);
77 static void factor_computed_gotos (void);
80 static void make_edges (void);
81 static void make_ctrl_stmt_edges (basic_block);
82 static void make_exit_edges (basic_block);
83 static void make_cond_expr_edges (basic_block);
84 static void make_switch_expr_edges (basic_block);
85 static void make_goto_expr_edges (basic_block);
86 static edge tree_redirect_edge_and_branch (edge, basic_block);
87 static edge tree_try_redirect_by_replacing_jump (edge, basic_block);
88 static void split_critical_edges (void);
90 /* Various helpers. */
91 static inline bool stmt_starts_bb_p (tree, tree);
92 static int tree_verify_flow_info (void);
93 static void tree_make_forwarder_block (edge);
94 static bool thread_jumps (void);
95 static bool tree_forwarder_block_p (basic_block);
96 static void bsi_commit_edge_inserts_1 (edge e);
97 static void tree_cfg2vcg (FILE *);
99 /* Flowgraph optimization and cleanup. */
100 static void tree_merge_blocks (basic_block, basic_block);
101 static bool tree_can_merge_blocks_p (basic_block, basic_block);
102 static void remove_bb (basic_block);
103 static bool cleanup_control_flow (void);
104 static bool cleanup_control_expr_graph (basic_block, block_stmt_iterator);
105 static edge find_taken_edge_cond_expr (basic_block, tree);
106 static edge find_taken_edge_switch_expr (basic_block, tree);
107 static tree find_case_label_for_value (tree, tree);
108 static bool phi_alternatives_equal (basic_block, edge, edge);
111 /*---------------------------------------------------------------------------
113 ---------------------------------------------------------------------------*/
115 /* Entry point to the CFG builder for trees. TP points to the list of
116 statements to be added to the flowgraph. */
119 build_tree_cfg (tree *tp)
121 /* Register specific tree functions. */
122 tree_register_cfg_hooks ();
124 /* Initialize rbi_pool. */
127 /* Initialize the basic block array. */
129 profile_status = PROFILE_ABSENT;
131 last_basic_block = 0;
132 VARRAY_BB_INIT (basic_block_info, initial_cfg_capacity, "basic_block_info");
133 memset ((void *) &cfg_stats, 0, sizeof (cfg_stats));
135 /* Build a mapping of labels to their associated blocks. */
136 VARRAY_BB_INIT (label_to_block_map, initial_cfg_capacity,
137 "label to block map");
139 ENTRY_BLOCK_PTR->next_bb = EXIT_BLOCK_PTR;
140 EXIT_BLOCK_PTR->prev_bb = ENTRY_BLOCK_PTR;
142 found_computed_goto = 0;
145 /* Computed gotos are hell to deal with, especially if there are
146 lots of them with a large number of destinations. So we factor
147 them to a common computed goto location before we build the
148 edge list. After we convert back to normal form, we will un-factor
149 the computed gotos since factoring introduces an unwanted jump. */
150 if (found_computed_goto)
151 factor_computed_gotos ();
153 /* Make sure there is always at least one block, even if it's empty. */
154 if (n_basic_blocks == 0)
155 create_empty_bb (ENTRY_BLOCK_PTR);
157 create_block_annotation (ENTRY_BLOCK_PTR);
158 create_block_annotation (EXIT_BLOCK_PTR);
160 /* Adjust the size of the array. */
161 VARRAY_GROW (basic_block_info, n_basic_blocks);
163 /* To speed up statement iterator walks, we first purge dead labels. */
164 cleanup_dead_labels ();
166 /* Group case nodes to reduce the number of edges.
167 We do this after cleaning up dead labels because otherwise we miss
168 a lot of obvious case merging opportunities. */
169 group_case_labels ();
171 /* Create the edges of the flowgraph. */
174 /* Debugging dumps. */
176 /* Write the flowgraph to a VCG file. */
178 int local_dump_flags;
179 FILE *dump_file = dump_begin (TDI_vcg, &local_dump_flags);
182 tree_cfg2vcg (dump_file);
183 dump_end (TDI_vcg, dump_file);
187 /* Dump a textual representation of the flowgraph. */
189 dump_tree_cfg (dump_file, dump_flags);
193 execute_build_cfg (void)
195 build_tree_cfg (&DECL_SAVED_TREE (current_function_decl));
198 struct tree_opt_pass pass_build_cfg =
202 execute_build_cfg, /* execute */
205 0, /* static_pass_number */
206 TV_TREE_CFG, /* tv_id */
207 PROP_gimple_leh, /* properties_required */
208 PROP_cfg, /* properties_provided */
209 0, /* properties_destroyed */
210 0, /* todo_flags_start */
211 TODO_verify_stmts, /* todo_flags_finish */
215 /* Search the CFG for any computed gotos. If found, factor them to a
216 common computed goto site. Also record the location of that site so
217 that we can un-factor the gotos after we have converted back to
221 factor_computed_gotos (void)
224 tree factored_label_decl = NULL;
226 tree factored_computed_goto_label = NULL;
227 tree factored_computed_goto = NULL;
229 /* We know there are one or more computed gotos in this function.
230 Examine the last statement in each basic block to see if the block
231 ends with a computed goto. */
235 block_stmt_iterator bsi = bsi_last (bb);
240 last = bsi_stmt (bsi);
242 /* Ignore the computed goto we create when we factor the original
244 if (last == factored_computed_goto)
247 /* If the last statement is a computed goto, factor it. */
248 if (computed_goto_p (last))
252 /* The first time we find a computed goto we need to create
253 the factored goto block and the variable each original
254 computed goto will use for their goto destination. */
255 if (! factored_computed_goto)
257 basic_block new_bb = create_empty_bb (bb);
258 block_stmt_iterator new_bsi = bsi_start (new_bb);
260 /* Create the destination of the factored goto. Each original
261 computed goto will put its desired destination into this
262 variable and jump to the label we create immediately
264 var = create_tmp_var (ptr_type_node, "gotovar");
266 /* Build a label for the new block which will contain the
267 factored computed goto. */
268 factored_label_decl = create_artificial_label ();
269 factored_computed_goto_label
270 = build1 (LABEL_EXPR, void_type_node, factored_label_decl);
271 bsi_insert_after (&new_bsi, factored_computed_goto_label,
274 /* Build our new computed goto. */
275 factored_computed_goto = build1 (GOTO_EXPR, void_type_node, var);
276 bsi_insert_after (&new_bsi, factored_computed_goto,
280 /* Copy the original computed goto's destination into VAR. */
281 assignment = build (MODIFY_EXPR, ptr_type_node,
282 var, GOTO_DESTINATION (last));
283 bsi_insert_before (&bsi, assignment, BSI_SAME_STMT);
285 /* And re-vector the computed goto to the new destination. */
286 GOTO_DESTINATION (last) = factored_label_decl;
292 /* Create annotations for a single basic block. */
295 create_block_annotation (basic_block bb)
297 /* Verify that the tree_annotations field is clear. */
298 gcc_assert (!bb->tree_annotations);
299 bb->tree_annotations = ggc_alloc_cleared (sizeof (struct bb_ann_d));
303 /* Free the annotations for all the basic blocks. */
305 static void free_blocks_annotations (void)
307 clear_blocks_annotations ();
311 /* Clear the annotations for all the basic blocks. */
314 clear_blocks_annotations (void)
318 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb)
319 bb->tree_annotations = NULL;
323 /* Build a flowgraph for the statement_list STMT_LIST. */
326 make_blocks (tree stmt_list)
328 tree_stmt_iterator i = tsi_start (stmt_list);
330 bool start_new_block = true;
331 bool first_stmt_of_list = true;
332 basic_block bb = ENTRY_BLOCK_PTR;
334 while (!tsi_end_p (i))
341 /* If the statement starts a new basic block or if we have determined
342 in a previous pass that we need to create a new block for STMT, do
344 if (start_new_block || stmt_starts_bb_p (stmt, prev_stmt))
346 if (!first_stmt_of_list)
347 stmt_list = tsi_split_statement_list_before (&i);
348 bb = create_basic_block (stmt_list, NULL, bb);
349 start_new_block = false;
352 /* Now add STMT to BB and create the subgraphs for special statement
354 set_bb_for_stmt (stmt, bb);
356 if (computed_goto_p (stmt))
357 found_computed_goto = true;
359 /* If STMT is a basic block terminator, set START_NEW_BLOCK for the
361 if (stmt_ends_bb_p (stmt))
362 start_new_block = true;
365 first_stmt_of_list = false;
370 /* Create and return a new empty basic block after bb AFTER. */
373 create_bb (void *h, void *e, basic_block after)
379 /* Create and initialize a new basic block. */
381 memset (bb, 0, sizeof (*bb));
383 bb->index = last_basic_block;
385 bb->stmt_list = h ? h : alloc_stmt_list ();
387 /* Add the new block to the linked list of blocks. */
388 link_block (bb, after);
390 /* Grow the basic block array if needed. */
391 if ((size_t) last_basic_block == VARRAY_SIZE (basic_block_info))
393 size_t new_size = last_basic_block + (last_basic_block + 3) / 4;
394 VARRAY_GROW (basic_block_info, new_size);
397 /* Add the newly created block to the array. */
398 BASIC_BLOCK (last_basic_block) = bb;
400 create_block_annotation (bb);
405 initialize_bb_rbi (bb);
410 /*---------------------------------------------------------------------------
412 ---------------------------------------------------------------------------*/
414 /* Join all the blocks in the flowgraph. */
421 /* Create an edge from entry to the first block with executable
423 make_edge (ENTRY_BLOCK_PTR, BASIC_BLOCK (0), EDGE_FALLTHRU);
425 /* Traverse basic block array placing edges. */
428 tree first = first_stmt (bb);
429 tree last = last_stmt (bb);
433 /* Edges for statements that always alter flow control. */
434 if (is_ctrl_stmt (last))
435 make_ctrl_stmt_edges (bb);
437 /* Edges for statements that sometimes alter flow control. */
438 if (is_ctrl_altering_stmt (last))
439 make_exit_edges (bb);
442 /* Finally, if no edges were created above, this is a regular
443 basic block that only needs a fallthru edge. */
444 if (EDGE_COUNT (bb->succs) == 0)
445 make_edge (bb, bb->next_bb, EDGE_FALLTHRU);
448 /* We do not care about fake edges, so remove any that the CFG
449 builder inserted for completeness. */
450 remove_fake_exit_edges ();
452 /* Clean up the graph and warn for unreachable code. */
457 /* Create edges for control statement at basic block BB. */
460 make_ctrl_stmt_edges (basic_block bb)
462 tree last = last_stmt (bb);
465 switch (TREE_CODE (last))
468 make_goto_expr_edges (bb);
472 make_edge (bb, EXIT_BLOCK_PTR, 0);
476 make_cond_expr_edges (bb);
480 make_switch_expr_edges (bb);
484 make_eh_edges (last);
485 /* Yet another NORETURN hack. */
486 if (EDGE_COUNT (bb->succs) == 0)
487 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
496 /* Create exit edges for statements in block BB that alter the flow of
497 control. Statements that alter the control flow are 'goto', 'return'
498 and calls to non-returning functions. */
501 make_exit_edges (basic_block bb)
503 tree last = last_stmt (bb), op;
506 switch (TREE_CODE (last))
509 /* If this function receives a nonlocal goto, then we need to
510 make edges from this call site to all the nonlocal goto
512 if (TREE_SIDE_EFFECTS (last)
513 && current_function_has_nonlocal_label)
514 make_goto_expr_edges (bb);
516 /* If this statement has reachable exception handlers, then
517 create abnormal edges to them. */
518 make_eh_edges (last);
520 /* Some calls are known not to return. For such calls we create
523 We really need to revamp how we build edges so that it's not
524 such a bloody pain to avoid creating edges for this case since
525 all we do is remove these edges when we're done building the
527 if (call_expr_flags (last) & (ECF_NORETURN | ECF_LONGJMP))
529 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
533 /* Don't forget the fall-thru edge. */
534 make_edge (bb, bb->next_bb, EDGE_FALLTHRU);
538 /* A MODIFY_EXPR may have a CALL_EXPR on its RHS and the CALL_EXPR
539 may have an abnormal edge. Search the RHS for this case and
540 create any required edges. */
541 op = get_call_expr_in (last);
542 if (op && TREE_SIDE_EFFECTS (op)
543 && current_function_has_nonlocal_label)
544 make_goto_expr_edges (bb);
546 make_eh_edges (last);
547 make_edge (bb, bb->next_bb, EDGE_FALLTHRU);
556 /* Create the edges for a COND_EXPR starting at block BB.
557 At this point, both clauses must contain only simple gotos. */
560 make_cond_expr_edges (basic_block bb)
562 tree entry = last_stmt (bb);
563 basic_block then_bb, else_bb;
564 tree then_label, else_label;
567 gcc_assert (TREE_CODE (entry) == COND_EXPR);
569 /* Entry basic blocks for each component. */
570 then_label = GOTO_DESTINATION (COND_EXPR_THEN (entry));
571 else_label = GOTO_DESTINATION (COND_EXPR_ELSE (entry));
572 then_bb = label_to_block (then_label);
573 else_bb = label_to_block (else_label);
575 make_edge (bb, then_bb, EDGE_TRUE_VALUE);
576 make_edge (bb, else_bb, EDGE_FALSE_VALUE);
580 /* Create the edges for a SWITCH_EXPR starting at block BB.
581 At this point, the switch body has been lowered and the
582 SWITCH_LABELS filled in, so this is in effect a multi-way branch. */
585 make_switch_expr_edges (basic_block bb)
587 tree entry = last_stmt (bb);
591 vec = SWITCH_LABELS (entry);
592 n = TREE_VEC_LENGTH (vec);
594 for (i = 0; i < n; ++i)
596 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
597 basic_block label_bb = label_to_block (lab);
598 make_edge (bb, label_bb, 0);
603 /* Return the basic block holding label DEST. */
606 label_to_block (tree dest)
608 int uid = LABEL_DECL_UID (dest);
610 /* We would die hard when faced by an undefined label. Emit a label to
611 the very first basic block. This will hopefully make even the dataflow
612 and undefined variable warnings quite right. */
613 if ((errorcount || sorrycount) && uid < 0)
615 block_stmt_iterator bsi = bsi_start (BASIC_BLOCK (0));
618 stmt = build1 (LABEL_EXPR, void_type_node, dest);
619 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
620 uid = LABEL_DECL_UID (dest);
622 return VARRAY_BB (label_to_block_map, uid);
626 /* Create edges for a goto statement at block BB. */
629 make_goto_expr_edges (basic_block bb)
632 basic_block target_bb;
634 block_stmt_iterator last = bsi_last (bb);
636 goto_t = bsi_stmt (last);
638 /* If the last statement is not a GOTO (i.e., it is a RETURN_EXPR,
639 CALL_EXPR or MODIFY_EXPR), then the edge is an abnormal edge resulting
640 from a nonlocal goto. */
641 if (TREE_CODE (goto_t) != GOTO_EXPR)
643 dest = error_mark_node;
648 dest = GOTO_DESTINATION (goto_t);
651 /* A GOTO to a local label creates normal edges. */
652 if (simple_goto_p (goto_t))
654 edge e = make_edge (bb, label_to_block (dest), EDGE_FALLTHRU);
655 #ifdef USE_MAPPED_LOCATION
656 e->goto_locus = EXPR_LOCATION (goto_t);
658 e->goto_locus = EXPR_LOCUS (goto_t);
664 /* Nothing more to do for nonlocal gotos. */
665 if (TREE_CODE (dest) == LABEL_DECL)
668 /* Computed gotos remain. */
671 /* Look for the block starting with the destination label. In the
672 case of a computed goto, make an edge to any label block we find
674 FOR_EACH_BB (target_bb)
676 block_stmt_iterator bsi;
678 for (bsi = bsi_start (target_bb); !bsi_end_p (bsi); bsi_next (&bsi))
680 tree target = bsi_stmt (bsi);
682 if (TREE_CODE (target) != LABEL_EXPR)
686 /* Computed GOTOs. Make an edge to every label block that has
687 been marked as a potential target for a computed goto. */
688 (FORCED_LABEL (LABEL_EXPR_LABEL (target)) && for_call == 0)
689 /* Nonlocal GOTO target. Make an edge to every label block
690 that has been marked as a potential target for a nonlocal
692 || (DECL_NONLOCAL (LABEL_EXPR_LABEL (target)) && for_call == 1))
694 make_edge (bb, target_bb, EDGE_ABNORMAL);
700 /* Degenerate case of computed goto with no labels. */
701 if (!for_call && EDGE_COUNT (bb->succs) == 0)
702 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
706 /*---------------------------------------------------------------------------
708 ---------------------------------------------------------------------------*/
710 /* Remove unreachable blocks and other miscellaneous clean up work. */
713 cleanup_tree_cfg (void)
717 timevar_push (TV_TREE_CLEANUP_CFG);
719 retval = cleanup_control_flow ();
720 retval |= delete_unreachable_blocks ();
722 /* thread_jumps sometimes leaves further transformation
723 opportunities for itself, so iterate on it until nothing
725 while (thread_jumps ())
728 #ifdef ENABLE_CHECKING
731 gcc_assert (!cleanup_control_flow ());
732 gcc_assert (!delete_unreachable_blocks ());
736 /* Merging the blocks creates no new opportunities for the other
737 optimizations, so do it here. */
742 #ifdef ENABLE_CHECKING
745 timevar_pop (TV_TREE_CLEANUP_CFG);
750 /* Cleanup useless labels in basic blocks. This is something we wish
751 to do early because it allows us to group case labels before creating
752 the edges for the CFG, and it speeds up block statement iterators in
754 We only run this pass once, running it more than once is probably not
757 /* A map from basic block index to the leading label of that block. */
758 static tree *label_for_bb;
760 /* Callback for for_each_eh_region. Helper for cleanup_dead_labels. */
762 update_eh_label (struct eh_region *region)
764 tree old_label = get_eh_region_tree_label (region);
768 basic_block bb = label_to_block (old_label);
770 /* ??? After optimizing, there may be EH regions with labels
771 that have already been removed from the function body, so
772 there is no basic block for them. */
776 new_label = label_for_bb[bb->index];
777 set_eh_region_tree_label (region, new_label);
781 /* Given LABEL return the first label in the same basic block. */
783 main_block_label (tree label)
785 basic_block bb = label_to_block (label);
787 /* label_to_block possibly inserted undefined label into the chain. */
788 if (!label_for_bb[bb->index])
789 label_for_bb[bb->index] = label;
790 return label_for_bb[bb->index];
793 /* Cleanup redundant labels. This is a three-step process:
794 1) Find the leading label for each block.
795 2) Redirect all references to labels to the leading labels.
796 3) Cleanup all useless labels. */
799 cleanup_dead_labels (void)
802 label_for_bb = xcalloc (last_basic_block, sizeof (tree));
804 /* Find a suitable label for each block. We use the first user-defined
805 label if there is one, or otherwise just the first label we see. */
808 block_stmt_iterator i;
810 for (i = bsi_start (bb); !bsi_end_p (i); bsi_next (&i))
812 tree label, stmt = bsi_stmt (i);
814 if (TREE_CODE (stmt) != LABEL_EXPR)
817 label = LABEL_EXPR_LABEL (stmt);
819 /* If we have not yet seen a label for the current block,
820 remember this one and see if there are more labels. */
821 if (! label_for_bb[bb->index])
823 label_for_bb[bb->index] = label;
827 /* If we did see a label for the current block already, but it
828 is an artificially created label, replace it if the current
829 label is a user defined label. */
830 if (! DECL_ARTIFICIAL (label)
831 && DECL_ARTIFICIAL (label_for_bb[bb->index]))
833 label_for_bb[bb->index] = label;
839 /* Now redirect all jumps/branches to the selected label.
840 First do so for each block ending in a control statement. */
843 tree stmt = last_stmt (bb);
847 switch (TREE_CODE (stmt))
851 tree true_branch, false_branch;
853 true_branch = COND_EXPR_THEN (stmt);
854 false_branch = COND_EXPR_ELSE (stmt);
856 GOTO_DESTINATION (true_branch)
857 = main_block_label (GOTO_DESTINATION (true_branch));
858 GOTO_DESTINATION (false_branch)
859 = main_block_label (GOTO_DESTINATION (false_branch));
867 tree vec = SWITCH_LABELS (stmt);
868 size_t n = TREE_VEC_LENGTH (vec);
870 /* Replace all destination labels. */
871 for (i = 0; i < n; ++i)
872 CASE_LABEL (TREE_VEC_ELT (vec, i))
873 = main_block_label (CASE_LABEL (TREE_VEC_ELT (vec, i)));
878 /* We have to handle GOTO_EXPRs until they're removed, and we don't
879 remove them until after we've created the CFG edges. */
881 if (! computed_goto_p (stmt))
883 GOTO_DESTINATION (stmt)
884 = main_block_label (GOTO_DESTINATION (stmt));
893 for_each_eh_region (update_eh_label);
895 /* Finally, purge dead labels. All user-defined labels and labels that
896 can be the target of non-local gotos are preserved. */
899 block_stmt_iterator i;
900 tree label_for_this_bb = label_for_bb[bb->index];
902 if (! label_for_this_bb)
905 for (i = bsi_start (bb); !bsi_end_p (i); )
907 tree label, stmt = bsi_stmt (i);
909 if (TREE_CODE (stmt) != LABEL_EXPR)
912 label = LABEL_EXPR_LABEL (stmt);
914 if (label == label_for_this_bb
915 || ! DECL_ARTIFICIAL (label)
916 || DECL_NONLOCAL (label))
926 /* Look for blocks ending in a multiway branch (a SWITCH_EXPR in GIMPLE),
927 and scan the sorted vector of cases. Combine the ones jumping to the
929 Eg. three separate entries 1: 2: 3: become one entry 1..3: */
932 group_case_labels (void)
938 tree stmt = last_stmt (bb);
939 if (stmt && TREE_CODE (stmt) == SWITCH_EXPR)
941 tree labels = SWITCH_LABELS (stmt);
942 int old_size = TREE_VEC_LENGTH (labels);
943 int i, j, new_size = old_size;
944 tree default_case = TREE_VEC_ELT (labels, old_size - 1);
947 /* The default label is always the last case in a switch
948 statement after gimplification. */
949 default_label = CASE_LABEL (default_case);
951 /* Look for possible opportunities to merge cases.
952 Ignore the last element of the label vector because it
953 must be the default case. */
955 while (i < old_size - 2)
957 tree base_case, base_label, base_high, type;
958 base_case = TREE_VEC_ELT (labels, i);
960 gcc_assert (base_case);
961 base_label = CASE_LABEL (base_case);
963 /* Discard cases that have the same destination as the
965 if (base_label == default_label)
967 TREE_VEC_ELT (labels, i) = NULL_TREE;
973 type = TREE_TYPE (CASE_LOW (base_case));
974 base_high = CASE_HIGH (base_case) ?
975 CASE_HIGH (base_case) : CASE_LOW (base_case);
977 /* Try to merge case labels. Break out when we reach the end
978 of the label vector or when we cannot merge the next case
979 label with the current one. */
980 while (i < old_size - 2)
982 tree merge_case = TREE_VEC_ELT (labels, ++i);
983 tree merge_label = CASE_LABEL (merge_case);
984 tree t = int_const_binop (PLUS_EXPR, base_high,
985 integer_one_node, 1);
987 /* Merge the cases if they jump to the same place,
988 and their ranges are consecutive. */
989 if (merge_label == base_label
990 && tree_int_cst_equal (CASE_LOW (merge_case), t))
992 base_high = CASE_HIGH (merge_case) ?
993 CASE_HIGH (merge_case) : CASE_LOW (merge_case);
994 CASE_HIGH (base_case) = base_high;
995 TREE_VEC_ELT (labels, i) = NULL_TREE;
1003 /* Compress the case labels in the label vector, and adjust the
1004 length of the vector. */
1005 for (i = 0, j = 0; i < new_size; i++)
1007 while (! TREE_VEC_ELT (labels, j))
1009 TREE_VEC_ELT (labels, i) = TREE_VEC_ELT (labels, j++);
1011 TREE_VEC_LENGTH (labels) = new_size;
1016 /* Checks whether we can merge block B into block A. */
1019 tree_can_merge_blocks_p (basic_block a, basic_block b)
1022 block_stmt_iterator bsi;
1024 if (EDGE_COUNT (a->succs) != 1)
1027 if (EDGE_SUCC (a, 0)->flags & EDGE_ABNORMAL)
1030 if (EDGE_SUCC (a, 0)->dest != b)
1033 if (b == EXIT_BLOCK_PTR)
1036 if (EDGE_COUNT (b->preds) > 1)
1039 /* If A ends by a statement causing exceptions or something similar, we
1040 cannot merge the blocks. */
1041 stmt = last_stmt (a);
1042 if (stmt && stmt_ends_bb_p (stmt))
1045 /* Do not allow a block with only a non-local label to be merged. */
1046 if (stmt && TREE_CODE (stmt) == LABEL_EXPR
1047 && DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)))
1050 /* There may be no phi nodes at the start of b. Most of these degenerate
1051 phi nodes should be cleaned up by kill_redundant_phi_nodes. */
1055 /* Do not remove user labels. */
1056 for (bsi = bsi_start (b); !bsi_end_p (bsi); bsi_next (&bsi))
1058 stmt = bsi_stmt (bsi);
1059 if (TREE_CODE (stmt) != LABEL_EXPR)
1061 if (!DECL_ARTIFICIAL (LABEL_EXPR_LABEL (stmt)))
1069 /* Merge block B into block A. */
1072 tree_merge_blocks (basic_block a, basic_block b)
1074 block_stmt_iterator bsi;
1075 tree_stmt_iterator last;
1078 fprintf (dump_file, "Merging blocks %d and %d\n", a->index, b->index);
1080 /* Ensure that B follows A. */
1081 move_block_after (b, a);
1083 gcc_assert (EDGE_SUCC (a, 0)->flags & EDGE_FALLTHRU);
1084 gcc_assert (!last_stmt (a) || !stmt_ends_bb_p (last_stmt (a)));
1086 /* Remove labels from B and set bb_for_stmt to A for other statements. */
1087 for (bsi = bsi_start (b); !bsi_end_p (bsi);)
1089 if (TREE_CODE (bsi_stmt (bsi)) == LABEL_EXPR)
1093 set_bb_for_stmt (bsi_stmt (bsi), a);
1098 /* Merge the chains. */
1099 last = tsi_last (a->stmt_list);
1100 tsi_link_after (&last, b->stmt_list, TSI_NEW_STMT);
1101 b->stmt_list = NULL;
1105 /* Walk the function tree removing unnecessary statements.
1107 * Empty statement nodes are removed
1109 * Unnecessary TRY_FINALLY and TRY_CATCH blocks are removed
1111 * Unnecessary COND_EXPRs are removed
1113 * Some unnecessary BIND_EXPRs are removed
1115 Clearly more work could be done. The trick is doing the analysis
1116 and removal fast enough to be a net improvement in compile times.
1118 Note that when we remove a control structure such as a COND_EXPR
1119 BIND_EXPR, or TRY block, we will need to repeat this optimization pass
1120 to ensure we eliminate all the useless code. */
1131 static void remove_useless_stmts_1 (tree *, struct rus_data *);
1134 remove_useless_stmts_warn_notreached (tree stmt)
1136 if (EXPR_HAS_LOCATION (stmt))
1138 location_t loc = EXPR_LOCATION (stmt);
1139 warning ("%Hwill never be executed", &loc);
1143 switch (TREE_CODE (stmt))
1145 case STATEMENT_LIST:
1147 tree_stmt_iterator i;
1148 for (i = tsi_start (stmt); !tsi_end_p (i); tsi_next (&i))
1149 if (remove_useless_stmts_warn_notreached (tsi_stmt (i)))
1155 if (remove_useless_stmts_warn_notreached (COND_EXPR_COND (stmt)))
1157 if (remove_useless_stmts_warn_notreached (COND_EXPR_THEN (stmt)))
1159 if (remove_useless_stmts_warn_notreached (COND_EXPR_ELSE (stmt)))
1163 case TRY_FINALLY_EXPR:
1164 case TRY_CATCH_EXPR:
1165 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt, 0)))
1167 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt, 1)))
1172 return remove_useless_stmts_warn_notreached (CATCH_BODY (stmt));
1173 case EH_FILTER_EXPR:
1174 return remove_useless_stmts_warn_notreached (EH_FILTER_FAILURE (stmt));
1176 return remove_useless_stmts_warn_notreached (BIND_EXPR_BLOCK (stmt));
1179 /* Not a live container. */
1187 remove_useless_stmts_cond (tree *stmt_p, struct rus_data *data)
1189 tree then_clause, else_clause, cond;
1190 bool save_has_label, then_has_label, else_has_label;
1192 save_has_label = data->has_label;
1193 data->has_label = false;
1194 data->last_goto = NULL;
1196 remove_useless_stmts_1 (&COND_EXPR_THEN (*stmt_p), data);
1198 then_has_label = data->has_label;
1199 data->has_label = false;
1200 data->last_goto = NULL;
1202 remove_useless_stmts_1 (&COND_EXPR_ELSE (*stmt_p), data);
1204 else_has_label = data->has_label;
1205 data->has_label = save_has_label | then_has_label | else_has_label;
1208 then_clause = COND_EXPR_THEN (*stmt_p);
1209 else_clause = COND_EXPR_ELSE (*stmt_p);
1210 cond = COND_EXPR_COND (*stmt_p);
1212 /* If neither arm does anything at all, we can remove the whole IF. */
1213 if (!TREE_SIDE_EFFECTS (then_clause) && !TREE_SIDE_EFFECTS (else_clause))
1215 *stmt_p = build_empty_stmt ();
1216 data->repeat = true;
1219 /* If there are no reachable statements in an arm, then we can
1220 zap the entire conditional. */
1221 else if (integer_nonzerop (cond) && !else_has_label)
1223 if (warn_notreached)
1224 remove_useless_stmts_warn_notreached (else_clause);
1225 *stmt_p = then_clause;
1226 data->repeat = true;
1228 else if (integer_zerop (cond) && !then_has_label)
1230 if (warn_notreached)
1231 remove_useless_stmts_warn_notreached (then_clause);
1232 *stmt_p = else_clause;
1233 data->repeat = true;
1236 /* Check a couple of simple things on then/else with single stmts. */
1239 tree then_stmt = expr_only (then_clause);
1240 tree else_stmt = expr_only (else_clause);
1242 /* Notice branches to a common destination. */
1243 if (then_stmt && else_stmt
1244 && TREE_CODE (then_stmt) == GOTO_EXPR
1245 && TREE_CODE (else_stmt) == GOTO_EXPR
1246 && (GOTO_DESTINATION (then_stmt) == GOTO_DESTINATION (else_stmt)))
1248 *stmt_p = then_stmt;
1249 data->repeat = true;
1252 /* If the THEN/ELSE clause merely assigns a value to a variable or
1253 parameter which is already known to contain that value, then
1254 remove the useless THEN/ELSE clause. */
1255 else if (TREE_CODE (cond) == VAR_DECL || TREE_CODE (cond) == PARM_DECL)
1258 && TREE_CODE (else_stmt) == MODIFY_EXPR
1259 && TREE_OPERAND (else_stmt, 0) == cond
1260 && integer_zerop (TREE_OPERAND (else_stmt, 1)))
1261 COND_EXPR_ELSE (*stmt_p) = alloc_stmt_list ();
1263 else if ((TREE_CODE (cond) == EQ_EXPR || TREE_CODE (cond) == NE_EXPR)
1264 && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL
1265 || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL)
1266 && TREE_CONSTANT (TREE_OPERAND (cond, 1)))
1268 tree stmt = (TREE_CODE (cond) == EQ_EXPR
1269 ? then_stmt : else_stmt);
1270 tree *location = (TREE_CODE (cond) == EQ_EXPR
1271 ? &COND_EXPR_THEN (*stmt_p)
1272 : &COND_EXPR_ELSE (*stmt_p));
1275 && TREE_CODE (stmt) == MODIFY_EXPR
1276 && TREE_OPERAND (stmt, 0) == TREE_OPERAND (cond, 0)
1277 && TREE_OPERAND (stmt, 1) == TREE_OPERAND (cond, 1))
1278 *location = alloc_stmt_list ();
1282 /* Protect GOTOs in the arm of COND_EXPRs from being removed. They
1283 would be re-introduced during lowering. */
1284 data->last_goto = NULL;
1289 remove_useless_stmts_tf (tree *stmt_p, struct rus_data *data)
1291 bool save_may_branch, save_may_throw;
1292 bool this_may_branch, this_may_throw;
1294 /* Collect may_branch and may_throw information for the body only. */
1295 save_may_branch = data->may_branch;
1296 save_may_throw = data->may_throw;
1297 data->may_branch = false;
1298 data->may_throw = false;
1299 data->last_goto = NULL;
1301 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 0), data);
1303 this_may_branch = data->may_branch;
1304 this_may_throw = data->may_throw;
1305 data->may_branch |= save_may_branch;
1306 data->may_throw |= save_may_throw;
1307 data->last_goto = NULL;
1309 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 1), data);
1311 /* If the body is empty, then we can emit the FINALLY block without
1312 the enclosing TRY_FINALLY_EXPR. */
1313 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 0)))
1315 *stmt_p = TREE_OPERAND (*stmt_p, 1);
1316 data->repeat = true;
1319 /* If the handler is empty, then we can emit the TRY block without
1320 the enclosing TRY_FINALLY_EXPR. */
1321 else if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 1)))
1323 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1324 data->repeat = true;
1327 /* If the body neither throws, nor branches, then we can safely
1328 string the TRY and FINALLY blocks together. */
1329 else if (!this_may_branch && !this_may_throw)
1331 tree stmt = *stmt_p;
1332 *stmt_p = TREE_OPERAND (stmt, 0);
1333 append_to_statement_list (TREE_OPERAND (stmt, 1), stmt_p);
1334 data->repeat = true;
1340 remove_useless_stmts_tc (tree *stmt_p, struct rus_data *data)
1342 bool save_may_throw, this_may_throw;
1343 tree_stmt_iterator i;
1346 /* Collect may_throw information for the body only. */
1347 save_may_throw = data->may_throw;
1348 data->may_throw = false;
1349 data->last_goto = NULL;
1351 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 0), data);
1353 this_may_throw = data->may_throw;
1354 data->may_throw = save_may_throw;
1356 /* If the body cannot throw, then we can drop the entire TRY_CATCH_EXPR. */
1357 if (!this_may_throw)
1359 if (warn_notreached)
1360 remove_useless_stmts_warn_notreached (TREE_OPERAND (*stmt_p, 1));
1361 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1362 data->repeat = true;
1366 /* Process the catch clause specially. We may be able to tell that
1367 no exceptions propagate past this point. */
1369 this_may_throw = true;
1370 i = tsi_start (TREE_OPERAND (*stmt_p, 1));
1371 stmt = tsi_stmt (i);
1372 data->last_goto = NULL;
1374 switch (TREE_CODE (stmt))
1377 for (; !tsi_end_p (i); tsi_next (&i))
1379 stmt = tsi_stmt (i);
1380 /* If we catch all exceptions, then the body does not
1381 propagate exceptions past this point. */
1382 if (CATCH_TYPES (stmt) == NULL)
1383 this_may_throw = false;
1384 data->last_goto = NULL;
1385 remove_useless_stmts_1 (&CATCH_BODY (stmt), data);
1389 case EH_FILTER_EXPR:
1390 if (EH_FILTER_MUST_NOT_THROW (stmt))
1391 this_may_throw = false;
1392 else if (EH_FILTER_TYPES (stmt) == NULL)
1393 this_may_throw = false;
1394 remove_useless_stmts_1 (&EH_FILTER_FAILURE (stmt), data);
1398 /* Otherwise this is a cleanup. */
1399 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 1), data);
1401 /* If the cleanup is empty, then we can emit the TRY block without
1402 the enclosing TRY_CATCH_EXPR. */
1403 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 1)))
1405 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1406 data->repeat = true;
1410 data->may_throw |= this_may_throw;
1415 remove_useless_stmts_bind (tree *stmt_p, struct rus_data *data)
1419 /* First remove anything underneath the BIND_EXPR. */
1420 remove_useless_stmts_1 (&BIND_EXPR_BODY (*stmt_p), data);
1422 /* If the BIND_EXPR has no variables, then we can pull everything
1423 up one level and remove the BIND_EXPR, unless this is the toplevel
1424 BIND_EXPR for the current function or an inlined function.
1426 When this situation occurs we will want to apply this
1427 optimization again. */
1428 block = BIND_EXPR_BLOCK (*stmt_p);
1429 if (BIND_EXPR_VARS (*stmt_p) == NULL_TREE
1430 && *stmt_p != DECL_SAVED_TREE (current_function_decl)
1432 || ! BLOCK_ABSTRACT_ORIGIN (block)
1433 || (TREE_CODE (BLOCK_ABSTRACT_ORIGIN (block))
1436 *stmt_p = BIND_EXPR_BODY (*stmt_p);
1437 data->repeat = true;
1443 remove_useless_stmts_goto (tree *stmt_p, struct rus_data *data)
1445 tree dest = GOTO_DESTINATION (*stmt_p);
1447 data->may_branch = true;
1448 data->last_goto = NULL;
1450 /* Record the last goto expr, so that we can delete it if unnecessary. */
1451 if (TREE_CODE (dest) == LABEL_DECL)
1452 data->last_goto = stmt_p;
1457 remove_useless_stmts_label (tree *stmt_p, struct rus_data *data)
1459 tree label = LABEL_EXPR_LABEL (*stmt_p);
1461 data->has_label = true;
1463 /* We do want to jump across non-local label receiver code. */
1464 if (DECL_NONLOCAL (label))
1465 data->last_goto = NULL;
1467 else if (data->last_goto && GOTO_DESTINATION (*data->last_goto) == label)
1469 *data->last_goto = build_empty_stmt ();
1470 data->repeat = true;
1473 /* ??? Add something here to delete unused labels. */
1477 /* If the function is "const" or "pure", then clear TREE_SIDE_EFFECTS on its
1478 decl. This allows us to eliminate redundant or useless
1479 calls to "const" functions.
1481 Gimplifier already does the same operation, but we may notice functions
1482 being const and pure once their calls has been gimplified, so we need
1483 to update the flag. */
1486 update_call_expr_flags (tree call)
1488 tree decl = get_callee_fndecl (call);
1491 if (call_expr_flags (call) & (ECF_CONST | ECF_PURE))
1492 TREE_SIDE_EFFECTS (call) = 0;
1493 if (TREE_NOTHROW (decl))
1494 TREE_NOTHROW (call) = 1;
1498 /* T is CALL_EXPR. Set current_function_calls_* flags. */
1501 notice_special_calls (tree t)
1503 int flags = call_expr_flags (t);
1505 if (flags & ECF_MAY_BE_ALLOCA)
1506 current_function_calls_alloca = true;
1507 if (flags & ECF_RETURNS_TWICE)
1508 current_function_calls_setjmp = true;
1512 /* Clear flags set by notice_special_calls. Used by dead code removal
1513 to update the flags. */
1516 clear_special_calls (void)
1518 current_function_calls_alloca = false;
1519 current_function_calls_setjmp = false;
1524 remove_useless_stmts_1 (tree *tp, struct rus_data *data)
1528 switch (TREE_CODE (t))
1531 remove_useless_stmts_cond (tp, data);
1534 case TRY_FINALLY_EXPR:
1535 remove_useless_stmts_tf (tp, data);
1538 case TRY_CATCH_EXPR:
1539 remove_useless_stmts_tc (tp, data);
1543 remove_useless_stmts_bind (tp, data);
1547 remove_useless_stmts_goto (tp, data);
1551 remove_useless_stmts_label (tp, data);
1556 data->last_goto = NULL;
1557 data->may_branch = true;
1562 data->last_goto = NULL;
1563 notice_special_calls (t);
1564 update_call_expr_flags (t);
1565 if (tree_could_throw_p (t))
1566 data->may_throw = true;
1570 data->last_goto = NULL;
1572 op = get_call_expr_in (t);
1575 update_call_expr_flags (op);
1576 notice_special_calls (op);
1578 if (tree_could_throw_p (t))
1579 data->may_throw = true;
1582 case STATEMENT_LIST:
1584 tree_stmt_iterator i = tsi_start (t);
1585 while (!tsi_end_p (i))
1588 if (IS_EMPTY_STMT (t))
1594 remove_useless_stmts_1 (tsi_stmt_ptr (i), data);
1597 if (TREE_CODE (t) == STATEMENT_LIST)
1599 tsi_link_before (&i, t, TSI_SAME_STMT);
1609 data->last_goto = NULL;
1613 data->last_goto = NULL;
1619 remove_useless_stmts (void)
1621 struct rus_data data;
1623 clear_special_calls ();
1627 memset (&data, 0, sizeof (data));
1628 remove_useless_stmts_1 (&DECL_SAVED_TREE (current_function_decl), &data);
1630 while (data.repeat);
1634 struct tree_opt_pass pass_remove_useless_stmts =
1636 "useless", /* name */
1638 remove_useless_stmts, /* execute */
1641 0, /* static_pass_number */
1643 PROP_gimple_any, /* properties_required */
1644 0, /* properties_provided */
1645 0, /* properties_destroyed */
1646 0, /* todo_flags_start */
1647 TODO_dump_func, /* todo_flags_finish */
1652 /* Remove obviously useless statements in basic block BB. */
1655 cfg_remove_useless_stmts_bb (basic_block bb)
1657 block_stmt_iterator bsi;
1658 tree stmt = NULL_TREE;
1659 tree cond, var = NULL_TREE, val = NULL_TREE;
1660 struct var_ann_d *ann;
1662 /* Check whether we come here from a condition, and if so, get the
1664 if (EDGE_COUNT (bb->preds) != 1
1665 || !(EDGE_PRED (bb, 0)->flags & (EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
1668 cond = COND_EXPR_COND (last_stmt (EDGE_PRED (bb, 0)->src));
1670 if (TREE_CODE (cond) == VAR_DECL || TREE_CODE (cond) == PARM_DECL)
1673 val = (EDGE_PRED (bb, 0)->flags & EDGE_FALSE_VALUE
1674 ? boolean_false_node : boolean_true_node);
1676 else if (TREE_CODE (cond) == TRUTH_NOT_EXPR
1677 && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL
1678 || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL))
1680 var = TREE_OPERAND (cond, 0);
1681 val = (EDGE_PRED (bb, 0)->flags & EDGE_FALSE_VALUE
1682 ? boolean_true_node : boolean_false_node);
1686 if (EDGE_PRED (bb, 0)->flags & EDGE_FALSE_VALUE)
1687 cond = invert_truthvalue (cond);
1688 if (TREE_CODE (cond) == EQ_EXPR
1689 && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL
1690 || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL)
1691 && (TREE_CODE (TREE_OPERAND (cond, 1)) == VAR_DECL
1692 || TREE_CODE (TREE_OPERAND (cond, 1)) == PARM_DECL
1693 || TREE_CONSTANT (TREE_OPERAND (cond, 1))))
1695 var = TREE_OPERAND (cond, 0);
1696 val = TREE_OPERAND (cond, 1);
1702 /* Only work for normal local variables. */
1703 ann = var_ann (var);
1706 || TREE_ADDRESSABLE (var))
1709 if (! TREE_CONSTANT (val))
1711 ann = var_ann (val);
1714 || TREE_ADDRESSABLE (val))
1718 /* Ignore floating point variables, since comparison behaves weird for
1720 if (FLOAT_TYPE_P (TREE_TYPE (var)))
1723 for (bsi = bsi_start (bb); !bsi_end_p (bsi);)
1725 stmt = bsi_stmt (bsi);
1727 /* If the THEN/ELSE clause merely assigns a value to a variable/parameter
1728 which is already known to contain that value, then remove the useless
1729 THEN/ELSE clause. */
1730 if (TREE_CODE (stmt) == MODIFY_EXPR
1731 && TREE_OPERAND (stmt, 0) == var
1732 && operand_equal_p (val, TREE_OPERAND (stmt, 1), 0))
1738 /* Invalidate the var if we encounter something that could modify it.
1739 Likewise for the value it was previously set to. Note that we only
1740 consider values that are either a VAR_DECL or PARM_DECL so we
1741 can test for conflict very simply. */
1742 if (TREE_CODE (stmt) == ASM_EXPR
1743 || (TREE_CODE (stmt) == MODIFY_EXPR
1744 && (TREE_OPERAND (stmt, 0) == var
1745 || TREE_OPERAND (stmt, 0) == val)))
1753 /* A CFG-aware version of remove_useless_stmts. */
1756 cfg_remove_useless_stmts (void)
1760 #ifdef ENABLE_CHECKING
1761 verify_flow_info ();
1766 cfg_remove_useless_stmts_bb (bb);
1771 /* Remove PHI nodes associated with basic block BB and all edges out of BB. */
1774 remove_phi_nodes_and_edges_for_unreachable_block (basic_block bb)
1778 /* Since this block is no longer reachable, we can just delete all
1779 of its PHI nodes. */
1780 phi = phi_nodes (bb);
1783 tree next = PHI_CHAIN (phi);
1784 remove_phi_node (phi, NULL_TREE, bb);
1788 /* Remove edges to BB's successors. */
1789 while (EDGE_COUNT (bb->succs) > 0)
1790 ssa_remove_edge (EDGE_SUCC (bb, 0));
1794 /* Remove statements of basic block BB. */
1797 remove_bb (basic_block bb)
1799 block_stmt_iterator i;
1800 source_locus loc = 0;
1804 fprintf (dump_file, "Removing basic block %d\n", bb->index);
1805 if (dump_flags & TDF_DETAILS)
1807 dump_bb (bb, dump_file, 0);
1808 fprintf (dump_file, "\n");
1812 /* Remove all the instructions in the block. */
1813 for (i = bsi_start (bb); !bsi_end_p (i); bsi_remove (&i))
1815 tree stmt = bsi_stmt (i);
1816 release_defs (stmt);
1818 set_bb_for_stmt (stmt, NULL);
1820 /* Don't warn for removed gotos. Gotos are often removed due to
1821 jump threading, thus resulting in bogus warnings. Not great,
1822 since this way we lose warnings for gotos in the original
1823 program that are indeed unreachable. */
1824 if (TREE_CODE (stmt) != GOTO_EXPR && EXPR_HAS_LOCATION (stmt) && !loc)
1825 #ifdef USE_MAPPED_LOCATION
1826 loc = EXPR_LOCATION (stmt);
1828 loc = EXPR_LOCUS (stmt);
1832 /* If requested, give a warning that the first statement in the
1833 block is unreachable. We walk statements backwards in the
1834 loop above, so the last statement we process is the first statement
1836 if (warn_notreached && loc)
1837 #ifdef USE_MAPPED_LOCATION
1838 warning ("%Hwill never be executed", &loc);
1840 warning ("%Hwill never be executed", loc);
1843 remove_phi_nodes_and_edges_for_unreachable_block (bb);
1846 /* Try to remove superfluous control structures. */
1849 cleanup_control_flow (void)
1852 block_stmt_iterator bsi;
1853 bool retval = false;
1858 bsi = bsi_last (bb);
1860 if (bsi_end_p (bsi))
1863 stmt = bsi_stmt (bsi);
1864 if (TREE_CODE (stmt) == COND_EXPR
1865 || TREE_CODE (stmt) == SWITCH_EXPR)
1866 retval |= cleanup_control_expr_graph (bb, bsi);
1872 /* Disconnect an unreachable block in the control expression starting
1876 cleanup_control_expr_graph (basic_block bb, block_stmt_iterator bsi)
1879 bool retval = false;
1880 tree expr = bsi_stmt (bsi), val;
1882 if (EDGE_COUNT (bb->succs) > 1)
1887 switch (TREE_CODE (expr))
1890 val = COND_EXPR_COND (expr);
1894 val = SWITCH_COND (expr);
1895 if (TREE_CODE (val) != INTEGER_CST)
1903 taken_edge = find_taken_edge (bb, val);
1907 /* Remove all the edges except the one that is always executed. */
1908 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
1910 if (e != taken_edge)
1912 taken_edge->probability += e->probability;
1913 taken_edge->count += e->count;
1914 ssa_remove_edge (e);
1920 if (taken_edge->probability > REG_BR_PROB_BASE)
1921 taken_edge->probability = REG_BR_PROB_BASE;
1924 taken_edge = EDGE_SUCC (bb, 0);
1927 taken_edge->flags = EDGE_FALLTHRU;
1929 /* We removed some paths from the cfg. */
1930 if (dom_computed[CDI_DOMINATORS] >= DOM_CONS_OK)
1931 dom_computed[CDI_DOMINATORS] = DOM_CONS_OK;
1937 /* Given a control block BB and a predicate VAL, return the edge that
1938 will be taken out of the block. If VAL does not match a unique
1939 edge, NULL is returned. */
1942 find_taken_edge (basic_block bb, tree val)
1946 stmt = last_stmt (bb);
1949 gcc_assert (is_ctrl_stmt (stmt));
1951 /* If VAL is a predicate of the form N RELOP N, where N is an
1952 SSA_NAME, we can usually determine its truth value. */
1953 if (val && COMPARISON_CLASS_P (val))
1956 /* If VAL is not a constant, we can't determine which edge might
1958 if (val == NULL || !really_constant_p (val))
1961 if (TREE_CODE (stmt) == COND_EXPR)
1962 return find_taken_edge_cond_expr (bb, val);
1964 if (TREE_CODE (stmt) == SWITCH_EXPR)
1965 return find_taken_edge_switch_expr (bb, val);
1967 return EDGE_SUCC (bb, 0);
1971 /* Given a constant value VAL and the entry block BB to a COND_EXPR
1972 statement, determine which of the two edges will be taken out of the
1973 block. Return NULL if either edge may be taken. */
1976 find_taken_edge_cond_expr (basic_block bb, tree val)
1978 edge true_edge, false_edge;
1980 extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
1982 /* If both edges of the branch lead to the same basic block, it doesn't
1983 matter which edge is taken. */
1984 if (true_edge->dest == false_edge->dest)
1987 /* Otherwise, try to determine which branch of the if() will be taken.
1988 If VAL is a constant but it can't be reduced to a 0 or a 1, then
1989 we don't really know which edge will be taken at runtime. This
1990 may happen when comparing addresses (e.g., if (&var1 == 4)). */
1991 if (integer_nonzerop (val))
1993 else if (integer_zerop (val))
2000 /* Given a constant value VAL and the entry block BB to a SWITCH_EXPR
2001 statement, determine which edge will be taken out of the block. Return
2002 NULL if any edge may be taken. */
2005 find_taken_edge_switch_expr (basic_block bb, tree val)
2007 tree switch_expr, taken_case;
2008 basic_block dest_bb;
2011 if (TREE_CODE (val) != INTEGER_CST)
2014 switch_expr = last_stmt (bb);
2015 taken_case = find_case_label_for_value (switch_expr, val);
2016 dest_bb = label_to_block (CASE_LABEL (taken_case));
2018 e = find_edge (bb, dest_bb);
2024 /* Return the CASE_LABEL_EXPR that SWITCH_EXPR will take for VAL.
2025 We can make optimal use here of the fact that the case labels are
2026 sorted: We can do a binary search for a case matching VAL. */
2029 find_case_label_for_value (tree switch_expr, tree val)
2031 tree vec = SWITCH_LABELS (switch_expr);
2032 size_t low, high, n = TREE_VEC_LENGTH (vec);
2033 tree default_case = TREE_VEC_ELT (vec, n - 1);
2035 for (low = -1, high = n - 1; high - low > 1; )
2037 size_t i = (high + low) / 2;
2038 tree t = TREE_VEC_ELT (vec, i);
2041 /* Cache the result of comparing CASE_LOW and val. */
2042 cmp = tree_int_cst_compare (CASE_LOW (t), val);
2049 if (CASE_HIGH (t) == NULL)
2051 /* A singe-valued case label. */
2057 /* A case range. We can only handle integer ranges. */
2058 if (cmp <= 0 && tree_int_cst_compare (CASE_HIGH (t), val) >= 0)
2063 return default_case;
2067 /* If all the PHI nodes in DEST have alternatives for E1 and E2 and
2068 those alternatives are equal in each of the PHI nodes, then return
2069 true, else return false. */
2072 phi_alternatives_equal (basic_block dest, edge e1, edge e2)
2074 tree phi, val1, val2;
2077 for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi))
2079 n1 = phi_arg_from_edge (phi, e1);
2080 n2 = phi_arg_from_edge (phi, e2);
2082 gcc_assert (n1 >= 0);
2083 gcc_assert (n2 >= 0);
2085 val1 = PHI_ARG_DEF (phi, n1);
2086 val2 = PHI_ARG_DEF (phi, n2);
2088 if (!operand_equal_p (val1, val2, 0))
2096 /*---------------------------------------------------------------------------
2098 ---------------------------------------------------------------------------*/
2100 /* Dump tree-specific information of block BB to file OUTF. */
2103 tree_dump_bb (basic_block bb, FILE *outf, int indent)
2105 dump_generic_bb (outf, bb, indent, TDF_VOPS);
2109 /* Dump a basic block on stderr. */
2112 debug_tree_bb (basic_block bb)
2114 dump_bb (bb, stderr, 0);
2118 /* Dump basic block with index N on stderr. */
2121 debug_tree_bb_n (int n)
2123 debug_tree_bb (BASIC_BLOCK (n));
2124 return BASIC_BLOCK (n);
2128 /* Dump the CFG on stderr.
2130 FLAGS are the same used by the tree dumping functions
2131 (see TDF_* in tree.h). */
2134 debug_tree_cfg (int flags)
2136 dump_tree_cfg (stderr, flags);
2140 /* Dump the program showing basic block boundaries on the given FILE.
2142 FLAGS are the same used by the tree dumping functions (see TDF_* in
2146 dump_tree_cfg (FILE *file, int flags)
2148 if (flags & TDF_DETAILS)
2150 const char *funcname
2151 = lang_hooks.decl_printable_name (current_function_decl, 2);
2154 fprintf (file, ";; Function %s\n\n", funcname);
2155 fprintf (file, ";; \n%d basic blocks, %d edges, last basic block %d.\n\n",
2156 n_basic_blocks, n_edges, last_basic_block);
2158 brief_dump_cfg (file);
2159 fprintf (file, "\n");
2162 if (flags & TDF_STATS)
2163 dump_cfg_stats (file);
2165 dump_function_to_file (current_function_decl, file, flags | TDF_BLOCKS);
2169 /* Dump CFG statistics on FILE. */
2172 dump_cfg_stats (FILE *file)
2174 static long max_num_merged_labels = 0;
2175 unsigned long size, total = 0;
2178 const char * const fmt_str = "%-30s%-13s%12s\n";
2179 const char * const fmt_str_1 = "%-30s%13d%11lu%c\n";
2180 const char * const fmt_str_3 = "%-43s%11lu%c\n";
2181 const char *funcname
2182 = lang_hooks.decl_printable_name (current_function_decl, 2);
2185 fprintf (file, "\nCFG Statistics for %s\n\n", funcname);
2187 fprintf (file, "---------------------------------------------------------\n");
2188 fprintf (file, fmt_str, "", " Number of ", "Memory");
2189 fprintf (file, fmt_str, "", " instances ", "used ");
2190 fprintf (file, "---------------------------------------------------------\n");
2192 size = n_basic_blocks * sizeof (struct basic_block_def);
2194 fprintf (file, fmt_str_1, "Basic blocks", n_basic_blocks,
2195 SCALE (size), LABEL (size));
2199 n_edges += EDGE_COUNT (bb->succs);
2200 size = n_edges * sizeof (struct edge_def);
2202 fprintf (file, fmt_str_1, "Edges", n_edges, SCALE (size), LABEL (size));
2204 size = n_basic_blocks * sizeof (struct bb_ann_d);
2206 fprintf (file, fmt_str_1, "Basic block annotations", n_basic_blocks,
2207 SCALE (size), LABEL (size));
2209 fprintf (file, "---------------------------------------------------------\n");
2210 fprintf (file, fmt_str_3, "Total memory used by CFG data", SCALE (total),
2212 fprintf (file, "---------------------------------------------------------\n");
2213 fprintf (file, "\n");
2215 if (cfg_stats.num_merged_labels > max_num_merged_labels)
2216 max_num_merged_labels = cfg_stats.num_merged_labels;
2218 fprintf (file, "Coalesced label blocks: %ld (Max so far: %ld)\n",
2219 cfg_stats.num_merged_labels, max_num_merged_labels);
2221 fprintf (file, "\n");
2225 /* Dump CFG statistics on stderr. Keep extern so that it's always
2226 linked in the final executable. */
2229 debug_cfg_stats (void)
2231 dump_cfg_stats (stderr);
2235 /* Dump the flowgraph to a .vcg FILE. */
2238 tree_cfg2vcg (FILE *file)
2243 const char *funcname
2244 = lang_hooks.decl_printable_name (current_function_decl, 2);
2246 /* Write the file header. */
2247 fprintf (file, "graph: { title: \"%s\"\n", funcname);
2248 fprintf (file, "node: { title: \"ENTRY\" label: \"ENTRY\" }\n");
2249 fprintf (file, "node: { title: \"EXIT\" label: \"EXIT\" }\n");
2251 /* Write blocks and edges. */
2252 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
2254 fprintf (file, "edge: { sourcename: \"ENTRY\" targetname: \"%d\"",
2257 if (e->flags & EDGE_FAKE)
2258 fprintf (file, " linestyle: dotted priority: 10");
2260 fprintf (file, " linestyle: solid priority: 100");
2262 fprintf (file, " }\n");
2268 enum tree_code head_code, end_code;
2269 const char *head_name, *end_name;
2272 tree first = first_stmt (bb);
2273 tree last = last_stmt (bb);
2277 head_code = TREE_CODE (first);
2278 head_name = tree_code_name[head_code];
2279 head_line = get_lineno (first);
2282 head_name = "no-statement";
2286 end_code = TREE_CODE (last);
2287 end_name = tree_code_name[end_code];
2288 end_line = get_lineno (last);
2291 end_name = "no-statement";
2293 fprintf (file, "node: { title: \"%d\" label: \"#%d\\n%s (%d)\\n%s (%d)\"}\n",
2294 bb->index, bb->index, head_name, head_line, end_name,
2297 FOR_EACH_EDGE (e, ei, bb->succs)
2299 if (e->dest == EXIT_BLOCK_PTR)
2300 fprintf (file, "edge: { sourcename: \"%d\" targetname: \"EXIT\"", bb->index);
2302 fprintf (file, "edge: { sourcename: \"%d\" targetname: \"%d\"", bb->index, e->dest->index);
2304 if (e->flags & EDGE_FAKE)
2305 fprintf (file, " priority: 10 linestyle: dotted");
2307 fprintf (file, " priority: 100 linestyle: solid");
2309 fprintf (file, " }\n");
2312 if (bb->next_bb != EXIT_BLOCK_PTR)
2316 fputs ("}\n\n", file);
2321 /*---------------------------------------------------------------------------
2322 Miscellaneous helpers
2323 ---------------------------------------------------------------------------*/
2325 /* Return true if T represents a stmt that always transfers control. */
2328 is_ctrl_stmt (tree t)
2330 return (TREE_CODE (t) == COND_EXPR
2331 || TREE_CODE (t) == SWITCH_EXPR
2332 || TREE_CODE (t) == GOTO_EXPR
2333 || TREE_CODE (t) == RETURN_EXPR
2334 || TREE_CODE (t) == RESX_EXPR);
2338 /* Return true if T is a statement that may alter the flow of control
2339 (e.g., a call to a non-returning function). */
2342 is_ctrl_altering_stmt (tree t)
2347 call = get_call_expr_in (t);
2350 /* A non-pure/const CALL_EXPR alters flow control if the current
2351 function has nonlocal labels. */
2352 if (TREE_SIDE_EFFECTS (call) && current_function_has_nonlocal_label)
2355 /* A CALL_EXPR also alters control flow if it does not return. */
2356 if (call_expr_flags (call) & (ECF_NORETURN | ECF_LONGJMP))
2360 /* If a statement can throw, it alters control flow. */
2361 return tree_can_throw_internal (t);
2365 /* Return true if T is a computed goto. */
2368 computed_goto_p (tree t)
2370 return (TREE_CODE (t) == GOTO_EXPR
2371 && TREE_CODE (GOTO_DESTINATION (t)) != LABEL_DECL);
2375 /* Checks whether EXPR is a simple local goto. */
2378 simple_goto_p (tree expr)
2380 return (TREE_CODE (expr) == GOTO_EXPR
2381 && TREE_CODE (GOTO_DESTINATION (expr)) == LABEL_DECL);
2385 /* Return true if T should start a new basic block. PREV_T is the
2386 statement preceding T. It is used when T is a label or a case label.
2387 Labels should only start a new basic block if their previous statement
2388 wasn't a label. Otherwise, sequence of labels would generate
2389 unnecessary basic blocks that only contain a single label. */
2392 stmt_starts_bb_p (tree t, tree prev_t)
2394 enum tree_code code;
2399 /* LABEL_EXPRs start a new basic block only if the preceding
2400 statement wasn't a label of the same type. This prevents the
2401 creation of consecutive blocks that have nothing but a single
2403 code = TREE_CODE (t);
2404 if (code == LABEL_EXPR)
2406 /* Nonlocal and computed GOTO targets always start a new block. */
2407 if (code == LABEL_EXPR
2408 && (DECL_NONLOCAL (LABEL_EXPR_LABEL (t))
2409 || FORCED_LABEL (LABEL_EXPR_LABEL (t))))
2412 if (prev_t && TREE_CODE (prev_t) == code)
2414 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (prev_t)))
2417 cfg_stats.num_merged_labels++;
2428 /* Return true if T should end a basic block. */
2431 stmt_ends_bb_p (tree t)
2433 return is_ctrl_stmt (t) || is_ctrl_altering_stmt (t);
2437 /* Add gotos that used to be represented implicitly in the CFG. */
2440 disband_implicit_edges (void)
2443 block_stmt_iterator last;
2450 last = bsi_last (bb);
2451 stmt = last_stmt (bb);
2453 if (stmt && TREE_CODE (stmt) == COND_EXPR)
2455 /* Remove superfluous gotos from COND_EXPR branches. Moved
2456 from cfg_remove_useless_stmts here since it violates the
2457 invariants for tree--cfg correspondence and thus fits better
2458 here where we do it anyway. */
2459 FOR_EACH_EDGE (e, ei, bb->succs)
2461 if (e->dest != bb->next_bb)
2464 if (e->flags & EDGE_TRUE_VALUE)
2465 COND_EXPR_THEN (stmt) = build_empty_stmt ();
2466 else if (e->flags & EDGE_FALSE_VALUE)
2467 COND_EXPR_ELSE (stmt) = build_empty_stmt ();
2470 e->flags |= EDGE_FALLTHRU;
2476 if (stmt && TREE_CODE (stmt) == RETURN_EXPR)
2478 /* Remove the RETURN_EXPR if we may fall though to the exit
2480 gcc_assert (EDGE_COUNT (bb->succs) == 1);
2481 gcc_assert (EDGE_SUCC (bb, 0)->dest == EXIT_BLOCK_PTR);
2483 if (bb->next_bb == EXIT_BLOCK_PTR
2484 && !TREE_OPERAND (stmt, 0))
2487 EDGE_SUCC (bb, 0)->flags |= EDGE_FALLTHRU;
2492 /* There can be no fallthru edge if the last statement is a control
2494 if (stmt && is_ctrl_stmt (stmt))
2497 /* Find a fallthru edge and emit the goto if necessary. */
2498 FOR_EACH_EDGE (e, ei, bb->succs)
2499 if (e->flags & EDGE_FALLTHRU)
2502 if (!e || e->dest == bb->next_bb)
2505 gcc_assert (e->dest != EXIT_BLOCK_PTR);
2506 label = tree_block_label (e->dest);
2508 stmt = build1 (GOTO_EXPR, void_type_node, label);
2509 #ifdef USE_MAPPED_LOCATION
2510 SET_EXPR_LOCATION (stmt, e->goto_locus);
2512 SET_EXPR_LOCUS (stmt, e->goto_locus);
2514 bsi_insert_after (&last, stmt, BSI_NEW_STMT);
2515 e->flags &= ~EDGE_FALLTHRU;
2519 /* Remove block annotations and other datastructures. */
2522 delete_tree_cfg_annotations (void)
2525 if (n_basic_blocks > 0)
2526 free_blocks_annotations ();
2528 label_to_block_map = NULL;
2535 /* Return the first statement in basic block BB. */
2538 first_stmt (basic_block bb)
2540 block_stmt_iterator i = bsi_start (bb);
2541 return !bsi_end_p (i) ? bsi_stmt (i) : NULL_TREE;
2545 /* Return the last statement in basic block BB. */
2548 last_stmt (basic_block bb)
2550 block_stmt_iterator b = bsi_last (bb);
2551 return !bsi_end_p (b) ? bsi_stmt (b) : NULL_TREE;
2555 /* Return a pointer to the last statement in block BB. */
2558 last_stmt_ptr (basic_block bb)
2560 block_stmt_iterator last = bsi_last (bb);
2561 return !bsi_end_p (last) ? bsi_stmt_ptr (last) : NULL;
2565 /* Return the last statement of an otherwise empty block. Return NULL
2566 if the block is totally empty, or if it contains more than one
2570 last_and_only_stmt (basic_block bb)
2572 block_stmt_iterator i = bsi_last (bb);
2578 last = bsi_stmt (i);
2583 /* Empty statements should no longer appear in the instruction stream.
2584 Everything that might have appeared before should be deleted by
2585 remove_useless_stmts, and the optimizers should just bsi_remove
2586 instead of smashing with build_empty_stmt.
2588 Thus the only thing that should appear here in a block containing
2589 one executable statement is a label. */
2590 prev = bsi_stmt (i);
2591 if (TREE_CODE (prev) == LABEL_EXPR)
2598 /* Mark BB as the basic block holding statement T. */
2601 set_bb_for_stmt (tree t, basic_block bb)
2603 if (TREE_CODE (t) == PHI_NODE)
2605 else if (TREE_CODE (t) == STATEMENT_LIST)
2607 tree_stmt_iterator i;
2608 for (i = tsi_start (t); !tsi_end_p (i); tsi_next (&i))
2609 set_bb_for_stmt (tsi_stmt (i), bb);
2613 stmt_ann_t ann = get_stmt_ann (t);
2616 /* If the statement is a label, add the label to block-to-labels map
2617 so that we can speed up edge creation for GOTO_EXPRs. */
2618 if (TREE_CODE (t) == LABEL_EXPR)
2622 t = LABEL_EXPR_LABEL (t);
2623 uid = LABEL_DECL_UID (t);
2626 LABEL_DECL_UID (t) = uid = cfun->last_label_uid++;
2627 if (VARRAY_SIZE (label_to_block_map) <= (unsigned) uid)
2628 VARRAY_GROW (label_to_block_map, 3 * uid / 2);
2631 /* We're moving an existing label. Make sure that we've
2632 removed it from the old block. */
2633 gcc_assert (!bb || !VARRAY_BB (label_to_block_map, uid));
2634 VARRAY_BB (label_to_block_map, uid) = bb;
2639 /* Finds iterator for STMT. */
2641 extern block_stmt_iterator
2642 stmt_for_bsi (tree stmt)
2644 block_stmt_iterator bsi;
2646 for (bsi = bsi_start (bb_for_stmt (stmt)); !bsi_end_p (bsi); bsi_next (&bsi))
2647 if (bsi_stmt (bsi) == stmt)
2653 /* Insert statement (or statement list) T before the statement
2654 pointed-to by iterator I. M specifies how to update iterator I
2655 after insertion (see enum bsi_iterator_update). */
2658 bsi_insert_before (block_stmt_iterator *i, tree t, enum bsi_iterator_update m)
2660 set_bb_for_stmt (t, i->bb);
2661 tsi_link_before (&i->tsi, t, m);
2666 /* Insert statement (or statement list) T after the statement
2667 pointed-to by iterator I. M specifies how to update iterator I
2668 after insertion (see enum bsi_iterator_update). */
2671 bsi_insert_after (block_stmt_iterator *i, tree t, enum bsi_iterator_update m)
2673 set_bb_for_stmt (t, i->bb);
2674 tsi_link_after (&i->tsi, t, m);
2679 /* Remove the statement pointed to by iterator I. The iterator is updated
2680 to the next statement. */
2683 bsi_remove (block_stmt_iterator *i)
2685 tree t = bsi_stmt (*i);
2686 set_bb_for_stmt (t, NULL);
2687 tsi_delink (&i->tsi);
2691 /* Move the statement at FROM so it comes right after the statement at TO. */
2694 bsi_move_after (block_stmt_iterator *from, block_stmt_iterator *to)
2696 tree stmt = bsi_stmt (*from);
2698 bsi_insert_after (to, stmt, BSI_SAME_STMT);
2702 /* Move the statement at FROM so it comes right before the statement at TO. */
2705 bsi_move_before (block_stmt_iterator *from, block_stmt_iterator *to)
2707 tree stmt = bsi_stmt (*from);
2709 bsi_insert_before (to, stmt, BSI_SAME_STMT);
2713 /* Move the statement at FROM to the end of basic block BB. */
2716 bsi_move_to_bb_end (block_stmt_iterator *from, basic_block bb)
2718 block_stmt_iterator last = bsi_last (bb);
2720 /* Have to check bsi_end_p because it could be an empty block. */
2721 if (!bsi_end_p (last) && is_ctrl_stmt (bsi_stmt (last)))
2722 bsi_move_before (from, &last);
2724 bsi_move_after (from, &last);
2728 /* Replace the contents of the statement pointed to by iterator BSI
2729 with STMT. If PRESERVE_EH_INFO is true, the exception handling
2730 information of the original statement is preserved. */
2733 bsi_replace (const block_stmt_iterator *bsi, tree stmt, bool preserve_eh_info)
2736 tree orig_stmt = bsi_stmt (*bsi);
2738 SET_EXPR_LOCUS (stmt, EXPR_LOCUS (orig_stmt));
2739 set_bb_for_stmt (stmt, bsi->bb);
2741 /* Preserve EH region information from the original statement, if
2742 requested by the caller. */
2743 if (preserve_eh_info)
2745 eh_region = lookup_stmt_eh_region (orig_stmt);
2747 add_stmt_to_eh_region (stmt, eh_region);
2750 *bsi_stmt_ptr (*bsi) = stmt;
2755 /* Insert the statement pointed-to by BSI into edge E. Every attempt
2756 is made to place the statement in an existing basic block, but
2757 sometimes that isn't possible. When it isn't possible, the edge is
2758 split and the statement is added to the new block.
2760 In all cases, the returned *BSI points to the correct location. The
2761 return value is true if insertion should be done after the location,
2762 or false if it should be done before the location. If new basic block
2763 has to be created, it is stored in *NEW_BB. */
2766 tree_find_edge_insert_loc (edge e, block_stmt_iterator *bsi,
2767 basic_block *new_bb)
2769 basic_block dest, src;
2775 /* If the destination has one predecessor which has no PHI nodes,
2776 insert there. Except for the exit block.
2778 The requirement for no PHI nodes could be relaxed. Basically we
2779 would have to examine the PHIs to prove that none of them used
2780 the value set by the statement we want to insert on E. That
2781 hardly seems worth the effort. */
2782 if (EDGE_COUNT (dest->preds) == 1
2783 && ! phi_nodes (dest)
2784 && dest != EXIT_BLOCK_PTR)
2786 *bsi = bsi_start (dest);
2787 if (bsi_end_p (*bsi))
2790 /* Make sure we insert after any leading labels. */
2791 tmp = bsi_stmt (*bsi);
2792 while (TREE_CODE (tmp) == LABEL_EXPR)
2795 if (bsi_end_p (*bsi))
2797 tmp = bsi_stmt (*bsi);
2800 if (bsi_end_p (*bsi))
2802 *bsi = bsi_last (dest);
2809 /* If the source has one successor, the edge is not abnormal and
2810 the last statement does not end a basic block, insert there.
2811 Except for the entry block. */
2813 if ((e->flags & EDGE_ABNORMAL) == 0
2814 && EDGE_COUNT (src->succs) == 1
2815 && src != ENTRY_BLOCK_PTR)
2817 *bsi = bsi_last (src);
2818 if (bsi_end_p (*bsi))
2821 tmp = bsi_stmt (*bsi);
2822 if (!stmt_ends_bb_p (tmp))
2825 /* Insert code just before returning the value. We may need to decompose
2826 the return in the case it contains non-trivial operand. */
2827 if (TREE_CODE (tmp) == RETURN_EXPR)
2829 tree op = TREE_OPERAND (tmp, 0);
2830 if (!is_gimple_val (op))
2832 gcc_assert (TREE_CODE (op) == MODIFY_EXPR);
2833 bsi_insert_before (bsi, op, BSI_NEW_STMT);
2834 TREE_OPERAND (tmp, 0) = TREE_OPERAND (op, 0);
2841 /* Otherwise, create a new basic block, and split this edge. */
2842 dest = split_edge (e);
2845 e = EDGE_PRED (dest, 0);
2850 /* This routine will commit all pending edge insertions, creating any new
2851 basic blocks which are necessary.
2853 If specified, NEW_BLOCKS returns a count of the number of new basic
2854 blocks which were created. */
2857 bsi_commit_edge_inserts (int *new_blocks)
2864 blocks = n_basic_blocks;
2866 bsi_commit_edge_inserts_1 (EDGE_SUCC (ENTRY_BLOCK_PTR, 0));
2869 FOR_EACH_EDGE (e, ei, bb->succs)
2870 bsi_commit_edge_inserts_1 (e);
2873 *new_blocks = n_basic_blocks - blocks;
2877 /* Commit insertions pending at edge E. */
2880 bsi_commit_edge_inserts_1 (edge e)
2882 if (PENDING_STMT (e))
2884 block_stmt_iterator bsi;
2885 tree stmt = PENDING_STMT (e);
2887 PENDING_STMT (e) = NULL_TREE;
2889 if (tree_find_edge_insert_loc (e, &bsi, NULL))
2890 bsi_insert_after (&bsi, stmt, BSI_NEW_STMT);
2892 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
2897 /* Add STMT to the pending list of edge E. No actual insertion is
2898 made until a call to bsi_commit_edge_inserts () is made. */
2901 bsi_insert_on_edge (edge e, tree stmt)
2903 append_to_statement_list (stmt, &PENDING_STMT (e));
2906 /* Similar to bsi_insert_on_edge+bsi_commit_edge_inserts. If new block has to
2907 be created, it is returned. */
2910 bsi_insert_on_edge_immediate (edge e, tree stmt)
2912 block_stmt_iterator bsi;
2913 basic_block new_bb = NULL;
2915 gcc_assert (!PENDING_STMT (e));
2917 if (tree_find_edge_insert_loc (e, &bsi, &new_bb))
2918 bsi_insert_after (&bsi, stmt, BSI_NEW_STMT);
2920 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
2925 /*---------------------------------------------------------------------------
2926 Tree specific functions for CFG manipulation
2927 ---------------------------------------------------------------------------*/
2929 /* Split a (typically critical) edge EDGE_IN. Return the new block.
2930 Abort on abnormal edges. */
2933 tree_split_edge (edge edge_in)
2935 basic_block new_bb, after_bb, dest, src;
2941 /* Abnormal edges cannot be split. */
2942 gcc_assert (!(edge_in->flags & EDGE_ABNORMAL));
2945 dest = edge_in->dest;
2947 /* Place the new block in the block list. Try to keep the new block
2948 near its "logical" location. This is of most help to humans looking
2949 at debugging dumps. */
2950 FOR_EACH_EDGE (e, ei, dest->preds)
2951 if (e->src->next_bb == dest)
2954 after_bb = dest->prev_bb;
2956 after_bb = edge_in->src;
2958 new_bb = create_empty_bb (after_bb);
2959 new_bb->frequency = EDGE_FREQUENCY (edge_in);
2960 new_bb->count = edge_in->count;
2961 new_edge = make_edge (new_bb, dest, EDGE_FALLTHRU);
2962 new_edge->probability = REG_BR_PROB_BASE;
2963 new_edge->count = edge_in->count;
2965 /* Find all the PHI arguments on the original edge, and change them to
2966 the new edge. Do it before redirection, so that the argument does not
2968 for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi))
2970 num_elem = PHI_NUM_ARGS (phi);
2971 for (i = 0; i < num_elem; i++)
2972 if (PHI_ARG_EDGE (phi, i) == edge_in)
2974 PHI_ARG_EDGE (phi, i) = new_edge;
2979 e = redirect_edge_and_branch (edge_in, new_bb);
2981 gcc_assert (!PENDING_STMT (edge_in));
2987 /* Return true when BB has label LABEL in it. */
2990 has_label_p (basic_block bb, tree label)
2992 block_stmt_iterator bsi;
2994 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
2996 tree stmt = bsi_stmt (bsi);
2998 if (TREE_CODE (stmt) != LABEL_EXPR)
3000 if (LABEL_EXPR_LABEL (stmt) == label)
3007 /* Callback for walk_tree, check that all elements with address taken are
3008 properly noticed as such. */
3011 verify_expr (tree *tp, int *walk_subtrees, void *data ATTRIBUTE_UNUSED)
3018 /* Check operand N for being valid GIMPLE and give error MSG if not.
3019 We check for constants explicitly since they are not considered
3020 gimple invariants if they overflowed. */
3021 #define CHECK_OP(N, MSG) \
3022 do { if (!CONSTANT_CLASS_P (TREE_OPERAND (t, N)) \
3023 && !is_gimple_val (TREE_OPERAND (t, N))) \
3024 { error (MSG); return TREE_OPERAND (t, N); }} while (0)
3026 switch (TREE_CODE (t))
3029 if (SSA_NAME_IN_FREE_LIST (t))
3031 error ("SSA name in freelist but still referenced");
3037 x = TREE_OPERAND (t, 0);
3038 if (TREE_CODE (x) == BIT_FIELD_REF
3039 && is_gimple_reg (TREE_OPERAND (x, 0)))
3041 error ("GIMPLE register modified with BIT_FIELD_REF");
3047 /* Skip any references (they will be checked when we recurse down the
3048 tree) and ensure that any variable used as a prefix is marked
3050 for (x = TREE_OPERAND (t, 0);
3051 (handled_component_p (x)
3052 || TREE_CODE (x) == REALPART_EXPR
3053 || TREE_CODE (x) == IMAGPART_EXPR);
3054 x = TREE_OPERAND (x, 0))
3057 if (TREE_CODE (x) != VAR_DECL && TREE_CODE (x) != PARM_DECL)
3059 if (!TREE_ADDRESSABLE (x))
3061 error ("address taken, but ADDRESSABLE bit not set");
3067 x = TREE_OPERAND (t, 0);
3068 if (TREE_CODE (TREE_TYPE (x)) != BOOLEAN_TYPE)
3070 error ("non-boolean used in condition");
3077 case FIX_TRUNC_EXPR:
3079 case FIX_FLOOR_EXPR:
3080 case FIX_ROUND_EXPR:
3085 case NON_LVALUE_EXPR:
3086 case TRUTH_NOT_EXPR:
3087 CHECK_OP (0, "Invalid operand to unary operator");
3094 case ARRAY_RANGE_REF:
3096 case VIEW_CONVERT_EXPR:
3097 /* We have a nest of references. Verify that each of the operands
3098 that determine where to reference is either a constant or a variable,
3099 verify that the base is valid, and then show we've already checked
3101 while (TREE_CODE (t) == REALPART_EXPR || TREE_CODE (t) == IMAGPART_EXPR
3102 || handled_component_p (t))
3104 if (TREE_CODE (t) == COMPONENT_REF && TREE_OPERAND (t, 2))
3105 CHECK_OP (2, "Invalid COMPONENT_REF offset operator");
3106 else if (TREE_CODE (t) == ARRAY_REF
3107 || TREE_CODE (t) == ARRAY_RANGE_REF)
3109 CHECK_OP (1, "Invalid array index.");
3110 if (TREE_OPERAND (t, 2))
3111 CHECK_OP (2, "Invalid array lower bound.");
3112 if (TREE_OPERAND (t, 3))
3113 CHECK_OP (3, "Invalid array stride.");
3115 else if (TREE_CODE (t) == BIT_FIELD_REF)
3117 CHECK_OP (1, "Invalid operand to BIT_FIELD_REF");
3118 CHECK_OP (2, "Invalid operand to BIT_FIELD_REF");
3121 t = TREE_OPERAND (t, 0);
3124 if (!CONSTANT_CLASS_P (t) && !is_gimple_lvalue (t))
3126 error ("Invalid reference prefix.");
3138 case UNORDERED_EXPR:
3149 case TRUNC_DIV_EXPR:
3151 case FLOOR_DIV_EXPR:
3152 case ROUND_DIV_EXPR:
3153 case TRUNC_MOD_EXPR:
3155 case FLOOR_MOD_EXPR:
3156 case ROUND_MOD_EXPR:
3158 case EXACT_DIV_EXPR:
3168 CHECK_OP (0, "Invalid operand to binary operator");
3169 CHECK_OP (1, "Invalid operand to binary operator");
3181 /* Verify STMT, return true if STMT is not in GIMPLE form.
3182 TODO: Implement type checking. */
3185 verify_stmt (tree stmt, bool last_in_block)
3189 if (!is_gimple_stmt (stmt))
3191 error ("Is not a valid GIMPLE statement.");
3195 addr = walk_tree (&stmt, verify_expr, NULL, NULL);
3198 debug_generic_stmt (addr);
3202 /* If the statement is marked as part of an EH region, then it is
3203 expected that the statement could throw. Verify that when we
3204 have optimizations that simplify statements such that we prove
3205 that they cannot throw, that we update other data structures
3207 if (lookup_stmt_eh_region (stmt) >= 0)
3209 if (!tree_could_throw_p (stmt))
3211 error ("Statement marked for throw, but doesn%'t.");
3214 if (!last_in_block && tree_can_throw_internal (stmt))
3216 error ("Statement marked for throw in middle of block.");
3224 debug_generic_stmt (stmt);
3229 /* Return true when the T can be shared. */
3232 tree_node_can_be_shared (tree t)
3234 if (IS_TYPE_OR_DECL_P (t)
3235 /* We check for constants explicitly since they are not considered
3236 gimple invariants if they overflowed. */
3237 || CONSTANT_CLASS_P (t)
3238 || is_gimple_min_invariant (t)
3239 || TREE_CODE (t) == SSA_NAME)
3242 while (((TREE_CODE (t) == ARRAY_REF || TREE_CODE (t) == ARRAY_RANGE_REF)
3243 /* We check for constants explicitly since they are not considered
3244 gimple invariants if they overflowed. */
3245 && (CONSTANT_CLASS_P (TREE_OPERAND (t, 1))
3246 || is_gimple_min_invariant (TREE_OPERAND (t, 1))))
3247 || (TREE_CODE (t) == COMPONENT_REF
3248 || TREE_CODE (t) == REALPART_EXPR
3249 || TREE_CODE (t) == IMAGPART_EXPR))
3250 t = TREE_OPERAND (t, 0);
3259 /* Called via walk_trees. Verify tree sharing. */
3262 verify_node_sharing (tree * tp, int *walk_subtrees, void *data)
3264 htab_t htab = (htab_t) data;
3267 if (tree_node_can_be_shared (*tp))
3269 *walk_subtrees = false;
3273 slot = htab_find_slot (htab, *tp, INSERT);
3282 /* Verify the GIMPLE statement chain. */
3288 block_stmt_iterator bsi;
3293 timevar_push (TV_TREE_STMT_VERIFY);
3294 htab = htab_create (37, htab_hash_pointer, htab_eq_pointer, NULL);
3301 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
3303 int phi_num_args = PHI_NUM_ARGS (phi);
3305 for (i = 0; i < phi_num_args; i++)
3307 tree t = PHI_ARG_DEF (phi, i);
3310 /* Addressable variables do have SSA_NAMEs but they
3311 are not considered gimple values. */
3312 if (TREE_CODE (t) != SSA_NAME
3313 && TREE_CODE (t) != FUNCTION_DECL
3314 && !is_gimple_val (t))
3316 error ("PHI def is not a GIMPLE value");
3317 debug_generic_stmt (phi);
3318 debug_generic_stmt (t);
3322 addr = walk_tree (&t, verify_expr, NULL, NULL);
3325 debug_generic_stmt (addr);
3329 addr = walk_tree (&t, verify_node_sharing, htab, NULL);
3332 error ("Incorrect sharing of tree nodes");
3333 debug_generic_stmt (phi);
3334 debug_generic_stmt (addr);
3340 for (bsi = bsi_start (bb); !bsi_end_p (bsi); )
3342 tree stmt = bsi_stmt (bsi);
3344 err |= verify_stmt (stmt, bsi_end_p (bsi));
3345 addr = walk_tree (&stmt, verify_node_sharing, htab, NULL);
3348 error ("Incorrect sharing of tree nodes");
3349 debug_generic_stmt (stmt);
3350 debug_generic_stmt (addr);
3357 internal_error ("verify_stmts failed.");
3360 timevar_pop (TV_TREE_STMT_VERIFY);
3364 /* Verifies that the flow information is OK. */
3367 tree_verify_flow_info (void)
3371 block_stmt_iterator bsi;
3376 if (ENTRY_BLOCK_PTR->stmt_list)
3378 error ("ENTRY_BLOCK has a statement list associated with it\n");
3382 if (EXIT_BLOCK_PTR->stmt_list)
3384 error ("EXIT_BLOCK has a statement list associated with it\n");
3388 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
3389 if (e->flags & EDGE_FALLTHRU)
3391 error ("Fallthru to exit from bb %d\n", e->src->index);
3397 bool found_ctrl_stmt = false;
3399 /* Skip labels on the start of basic block. */
3400 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3402 if (TREE_CODE (bsi_stmt (bsi)) != LABEL_EXPR)
3405 if (label_to_block (LABEL_EXPR_LABEL (bsi_stmt (bsi))) != bb)
3407 error ("Label %s to block does not match in bb %d\n",
3408 IDENTIFIER_POINTER (DECL_NAME (bsi_stmt (bsi))),
3413 if (decl_function_context (LABEL_EXPR_LABEL (bsi_stmt (bsi)))
3414 != current_function_decl)
3416 error ("Label %s has incorrect context in bb %d\n",
3417 IDENTIFIER_POINTER (DECL_NAME (bsi_stmt (bsi))),
3423 /* Verify that body of basic block BB is free of control flow. */
3424 for (; !bsi_end_p (bsi); bsi_next (&bsi))
3426 tree stmt = bsi_stmt (bsi);
3428 if (found_ctrl_stmt)
3430 error ("Control flow in the middle of basic block %d\n",
3435 if (stmt_ends_bb_p (stmt))
3436 found_ctrl_stmt = true;
3438 if (TREE_CODE (stmt) == LABEL_EXPR)
3440 error ("Label %s in the middle of basic block %d\n",
3441 IDENTIFIER_POINTER (DECL_NAME (stmt)),
3446 bsi = bsi_last (bb);
3447 if (bsi_end_p (bsi))
3450 stmt = bsi_stmt (bsi);
3452 if (is_ctrl_stmt (stmt))
3454 FOR_EACH_EDGE (e, ei, bb->succs)
3455 if (e->flags & EDGE_FALLTHRU)
3457 error ("Fallthru edge after a control statement in bb %d \n",
3463 switch (TREE_CODE (stmt))
3469 if (TREE_CODE (COND_EXPR_THEN (stmt)) != GOTO_EXPR
3470 || TREE_CODE (COND_EXPR_ELSE (stmt)) != GOTO_EXPR)
3472 error ("Structured COND_EXPR at the end of bb %d\n", bb->index);
3476 extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
3478 if (!true_edge || !false_edge
3479 || !(true_edge->flags & EDGE_TRUE_VALUE)
3480 || !(false_edge->flags & EDGE_FALSE_VALUE)
3481 || (true_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL))
3482 || (false_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL))
3483 || EDGE_COUNT (bb->succs) >= 3)
3485 error ("Wrong outgoing edge flags at end of bb %d\n",
3490 if (!has_label_p (true_edge->dest,
3491 GOTO_DESTINATION (COND_EXPR_THEN (stmt))))
3493 error ("%<then%> label does not match edge at end of bb %d\n",
3498 if (!has_label_p (false_edge->dest,
3499 GOTO_DESTINATION (COND_EXPR_ELSE (stmt))))
3501 error ("%<else%> label does not match edge at end of bb %d\n",
3509 if (simple_goto_p (stmt))
3511 error ("Explicit goto at end of bb %d\n", bb->index);
3516 /* FIXME. We should double check that the labels in the
3517 destination blocks have their address taken. */
3518 FOR_EACH_EDGE (e, ei, bb->succs)
3519 if ((e->flags & (EDGE_FALLTHRU | EDGE_TRUE_VALUE
3520 | EDGE_FALSE_VALUE))
3521 || !(e->flags & EDGE_ABNORMAL))
3523 error ("Wrong outgoing edge flags at end of bb %d\n",
3531 if (EDGE_COUNT (bb->succs) != 1
3532 || (EDGE_SUCC (bb, 0)->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL
3533 | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
3535 error ("Wrong outgoing edge flags at end of bb %d\n", bb->index);
3538 if (EDGE_SUCC (bb, 0)->dest != EXIT_BLOCK_PTR)
3540 error ("Return edge does not point to exit in bb %d\n",
3553 vec = SWITCH_LABELS (stmt);
3554 n = TREE_VEC_LENGTH (vec);
3556 /* Mark all the destination basic blocks. */
3557 for (i = 0; i < n; ++i)
3559 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
3560 basic_block label_bb = label_to_block (lab);
3562 gcc_assert (!label_bb->aux || label_bb->aux == (void *)1);
3563 label_bb->aux = (void *)1;
3566 /* Verify that the case labels are sorted. */
3567 prev = TREE_VEC_ELT (vec, 0);
3568 for (i = 1; i < n - 1; ++i)
3570 tree c = TREE_VEC_ELT (vec, i);
3573 error ("Found default case not at end of case vector");
3577 if (! tree_int_cst_lt (CASE_LOW (prev), CASE_LOW (c)))
3579 error ("Case labels not sorted:\n ");
3580 print_generic_expr (stderr, prev, 0);
3581 fprintf (stderr," is greater than ");
3582 print_generic_expr (stderr, c, 0);
3583 fprintf (stderr," but comes before it.\n");
3588 if (CASE_LOW (TREE_VEC_ELT (vec, n - 1)))
3590 error ("No default case found at end of case vector");
3594 FOR_EACH_EDGE (e, ei, bb->succs)
3598 error ("Extra outgoing edge %d->%d\n",
3599 bb->index, e->dest->index);
3602 e->dest->aux = (void *)2;
3603 if ((e->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL
3604 | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
3606 error ("Wrong outgoing edge flags at end of bb %d\n",
3612 /* Check that we have all of them. */
3613 for (i = 0; i < n; ++i)
3615 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
3616 basic_block label_bb = label_to_block (lab);
3618 if (label_bb->aux != (void *)2)
3620 error ("Missing edge %i->%i\n",
3621 bb->index, label_bb->index);
3626 FOR_EACH_EDGE (e, ei, bb->succs)
3627 e->dest->aux = (void *)0;
3634 if (dom_computed[CDI_DOMINATORS] >= DOM_NO_FAST_QUERY)
3635 verify_dominators (CDI_DOMINATORS);
3641 /* Updates phi nodes after creating a forwarder block joined
3642 by edge FALLTHRU. */
3645 tree_make_forwarder_block (edge fallthru)
3649 basic_block dummy, bb;
3650 tree phi, new_phi, var, prev, next;
3652 dummy = fallthru->src;
3653 bb = fallthru->dest;
3655 if (EDGE_COUNT (bb->preds) == 1)
3658 /* If we redirected a branch we must create new phi nodes at the
3660 for (phi = phi_nodes (dummy); phi; phi = PHI_CHAIN (phi))
3662 var = PHI_RESULT (phi);
3663 new_phi = create_phi_node (var, bb);
3664 SSA_NAME_DEF_STMT (var) = new_phi;
3665 SET_PHI_RESULT (phi, make_ssa_name (SSA_NAME_VAR (var), phi));
3666 add_phi_arg (&new_phi, PHI_RESULT (phi), fallthru);
3669 /* Ensure that the PHI node chain is in the same order. */
3671 for (phi = phi_nodes (bb); phi; phi = next)
3673 next = PHI_CHAIN (phi);
3674 PHI_CHAIN (phi) = prev;
3677 set_phi_nodes (bb, prev);
3679 /* Add the arguments we have stored on edges. */
3680 FOR_EACH_EDGE (e, ei, bb->preds)
3685 for (phi = phi_nodes (bb), var = PENDING_STMT (e);
3687 phi = PHI_CHAIN (phi), var = TREE_CHAIN (var))
3688 add_phi_arg (&phi, TREE_VALUE (var), e);
3690 PENDING_STMT (e) = NULL;
3695 /* Return true if basic block BB does nothing except pass control
3696 flow to another block and that we can safely insert a label at
3697 the start of the successor block.
3699 As a precondition, we require that BB be not equal to
3703 tree_forwarder_block_p (basic_block bb)
3705 block_stmt_iterator bsi;
3709 /* If we have already determined that this block is not forwardable,
3710 then no further checks are necessary. */
3711 if (! bb_ann (bb)->forwardable)
3714 /* BB must have a single outgoing edge. */
3715 if (EDGE_COUNT (bb->succs) != 1
3716 /* BB can not have any PHI nodes. This could potentially be
3717 relaxed early in compilation if we re-rewrote the variables
3718 appearing in any PHI nodes in forwarder blocks. */
3720 /* BB may not be a predecessor of EXIT_BLOCK_PTR. */
3721 || EDGE_SUCC (bb, 0)->dest == EXIT_BLOCK_PTR
3722 /* BB may not have an abnormal outgoing edge. */
3723 || (EDGE_SUCC (bb, 0)->flags & EDGE_ABNORMAL))
3725 bb_ann (bb)->forwardable = 0;
3730 gcc_assert (bb != ENTRY_BLOCK_PTR);
3733 /* Successors of the entry block are not forwarders. */
3734 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
3737 bb_ann (bb)->forwardable = 0;
3741 /* Now walk through the statements. We can ignore labels, anything else
3742 means this is not a forwarder block. */
3743 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3745 tree stmt = bsi_stmt (bsi);
3747 switch (TREE_CODE (stmt))
3750 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)))
3755 bb_ann (bb)->forwardable = 0;
3764 /* Thread jumps over empty statements.
3766 This code should _not_ thread over obviously equivalent conditions
3767 as that requires nontrivial updates to the SSA graph.
3769 As a precondition, we require that all basic blocks be reachable.
3770 That is, there should be no opportunities left for
3771 delete_unreachable_blocks. */
3777 basic_block bb, dest, tmp, old_dest, curr, dom;
3780 bool retval = false;
3783 bb_ann (bb)->forwardable = 1;
3789 /* Don't waste time on forwarders. */
3790 if (tree_forwarder_block_p (bb))
3793 /* This block is now part of a forwarding path, mark it as not
3794 forwardable so that we can detect loops. This bit will be
3796 bb_ann (bb)->forwardable = 0;
3798 /* Examine each of our block's successors to see if it is
3800 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
3805 /* If the edge is abnormal or its destination is not
3806 forwardable, then there's nothing to do. */
3807 if ((e->flags & EDGE_ABNORMAL)
3808 || !tree_forwarder_block_p (e->dest))
3815 freq = EDGE_FREQUENCY (e);
3817 /* Now walk through as many forwarder blocks as possible to
3818 find the ultimate destination we want to thread our jump
3820 last = EDGE_SUCC (e->dest, 0);
3821 bb_ann (e->dest)->forwardable = 0;
3822 for (dest = EDGE_SUCC (e->dest, 0)->dest;
3823 tree_forwarder_block_p (dest);
3824 last = EDGE_SUCC (dest, 0),
3825 dest = EDGE_SUCC (dest, 0)->dest)
3826 bb_ann (dest)->forwardable = 0;
3828 /* Reset the forwardable marks to 1. */
3831 tmp = EDGE_SUCC (tmp, 0)->dest)
3832 bb_ann (tmp)->forwardable = 1;
3834 if (dest == e->dest)
3840 old = find_edge (bb, dest);
3843 /* If there already is an edge, check whether the values
3844 in phi nodes differ. */
3845 if (!phi_alternatives_equal (dest, last, old))
3847 /* The previous block is forwarder. Redirect our jump
3848 to that target instead since we know it has no PHI
3849 nodes that will need updating. */
3852 /* That might mean that no forwarding at all is possible. */
3853 if (dest == e->dest)
3859 old = find_edge (bb, dest);
3863 /* Perform the redirection. */
3866 e = redirect_edge_and_branch (e, dest);
3868 /* Update the profile. */
3869 if (profile_status != PROFILE_ABSENT)
3870 for (curr = old_dest; curr != dest; curr = EDGE_SUCC (curr, 0)->dest)
3872 curr->frequency -= freq;
3873 if (curr->frequency < 0)
3874 curr->frequency = 0;
3875 curr->count -= count;
3876 if (curr->count < 0)
3878 EDGE_SUCC (curr, 0)->count -= count;
3879 if (EDGE_SUCC (curr, 0)->count < 0)
3880 EDGE_SUCC (curr, 0)->count = 0;
3885 /* Update PHI nodes. We know that the new argument should
3886 have the same value as the argument associated with LAST.
3887 Otherwise we would have changed our target block above. */
3888 for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi))
3890 arg = phi_arg_from_edge (phi, last);
3891 gcc_assert (arg >= 0);
3892 add_phi_arg (&phi, PHI_ARG_DEF (phi, arg), e);
3896 /* Remove the unreachable blocks (observe that if all blocks
3897 were reachable before, only those in the path we threaded
3898 over and did not have any predecessor outside of the path
3899 become unreachable). */
3900 for (; old_dest != dest; old_dest = tmp)
3902 tmp = EDGE_SUCC (old_dest, 0)->dest;
3904 if (EDGE_COUNT (old_dest->preds) > 0)
3907 delete_basic_block (old_dest);
3910 /* Update the dominators. */
3911 if (dom_computed[CDI_DOMINATORS] >= DOM_CONS_OK)
3913 /* If the dominator of the destination was in the path, set its
3914 dominator to the start of the redirected edge. */
3915 if (get_immediate_dominator (CDI_DOMINATORS, old_dest) == NULL)
3916 set_immediate_dominator (CDI_DOMINATORS, old_dest, bb);
3918 /* Now proceed like if we forwarded just over one edge at a time.
3919 Algorithm for forwarding edge S --> A over edge A --> B then
3923 && !dominated_by (S, B))
3924 idom (B) = idom (A);
3925 recount_idom (A); */
3927 for (; old_dest != dest; old_dest = tmp)
3929 tmp = EDGE_SUCC (old_dest, 0)->dest;
3931 if (get_immediate_dominator (CDI_DOMINATORS, tmp) == old_dest
3932 && !dominated_by_p (CDI_DOMINATORS, bb, tmp))
3934 dom = get_immediate_dominator (CDI_DOMINATORS, old_dest);
3935 set_immediate_dominator (CDI_DOMINATORS, tmp, dom);
3938 dom = recount_dominator (CDI_DOMINATORS, old_dest);
3939 set_immediate_dominator (CDI_DOMINATORS, old_dest, dom);
3944 /* Reset the forwardable bit on our block since it's no longer in
3945 a forwarding chain path. */
3946 bb_ann (bb)->forwardable = 1;
3953 /* Return a non-special label in the head of basic block BLOCK.
3954 Create one if it doesn't exist. */
3957 tree_block_label (basic_block bb)
3959 block_stmt_iterator i, s = bsi_start (bb);
3963 for (i = s; !bsi_end_p (i); first = false, bsi_next (&i))
3965 stmt = bsi_stmt (i);
3966 if (TREE_CODE (stmt) != LABEL_EXPR)
3968 label = LABEL_EXPR_LABEL (stmt);
3969 if (!DECL_NONLOCAL (label))
3972 bsi_move_before (&i, &s);
3977 label = create_artificial_label ();
3978 stmt = build1 (LABEL_EXPR, void_type_node, label);
3979 bsi_insert_before (&s, stmt, BSI_NEW_STMT);
3984 /* Attempt to perform edge redirection by replacing a possibly complex
3985 jump instruction by a goto or by removing the jump completely.
3986 This can apply only if all edges now point to the same block. The
3987 parameters and return values are equivalent to
3988 redirect_edge_and_branch. */
3991 tree_try_redirect_by_replacing_jump (edge e, basic_block target)
3993 basic_block src = e->src;
3995 block_stmt_iterator b;
3999 /* Verify that all targets will be TARGET. */
4000 FOR_EACH_EDGE (tmp, ei, src->succs)
4001 if (tmp->dest != target && tmp != e)
4010 stmt = bsi_stmt (b);
4012 if (TREE_CODE (stmt) == COND_EXPR
4013 || TREE_CODE (stmt) == SWITCH_EXPR)
4016 e = ssa_redirect_edge (e, target);
4017 e->flags = EDGE_FALLTHRU;
4025 /* Redirect E to DEST. Return NULL on failure. Otherwise, return the
4026 edge representing the redirected branch. */
4029 tree_redirect_edge_and_branch (edge e, basic_block dest)
4031 basic_block bb = e->src;
4032 block_stmt_iterator bsi;
4036 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
4039 if (e->src != ENTRY_BLOCK_PTR
4040 && (ret = tree_try_redirect_by_replacing_jump (e, dest)))
4043 if (e->dest == dest)
4046 label = tree_block_label (dest);
4048 bsi = bsi_last (bb);
4049 stmt = bsi_end_p (bsi) ? NULL : bsi_stmt (bsi);
4051 switch (stmt ? TREE_CODE (stmt) : ERROR_MARK)
4054 stmt = (e->flags & EDGE_TRUE_VALUE
4055 ? COND_EXPR_THEN (stmt)
4056 : COND_EXPR_ELSE (stmt));
4057 GOTO_DESTINATION (stmt) = label;
4061 /* No non-abnormal edges should lead from a non-simple goto, and
4062 simple ones should be represented implicitly. */
4067 tree vec = SWITCH_LABELS (stmt);
4068 size_t i, n = TREE_VEC_LENGTH (vec);
4070 for (i = 0; i < n; ++i)
4072 tree elt = TREE_VEC_ELT (vec, i);
4073 if (label_to_block (CASE_LABEL (elt)) == e->dest)
4074 CASE_LABEL (elt) = label;
4081 e->flags |= EDGE_FALLTHRU;
4085 /* Otherwise it must be a fallthru edge, and we don't need to
4086 do anything besides redirecting it. */
4087 gcc_assert (e->flags & EDGE_FALLTHRU);
4091 /* Update/insert PHI nodes as necessary. */
4093 /* Now update the edges in the CFG. */
4094 e = ssa_redirect_edge (e, dest);
4100 /* Simple wrapper, as we can always redirect fallthru edges. */
4103 tree_redirect_edge_and_branch_force (edge e, basic_block dest)
4105 e = tree_redirect_edge_and_branch (e, dest);
4112 /* Splits basic block BB after statement STMT (but at least after the
4113 labels). If STMT is NULL, BB is split just after the labels. */
4116 tree_split_block (basic_block bb, void *stmt)
4118 block_stmt_iterator bsi, bsi_tgt;
4124 new_bb = create_empty_bb (bb);
4126 /* Redirect the outgoing edges. */
4127 new_bb->succs = bb->succs;
4129 FOR_EACH_EDGE (e, ei, new_bb->succs)
4132 if (stmt && TREE_CODE ((tree) stmt) == LABEL_EXPR)
4135 /* Move everything from BSI to the new basic block. */
4136 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4138 act = bsi_stmt (bsi);
4139 if (TREE_CODE (act) == LABEL_EXPR)
4152 bsi_tgt = bsi_start (new_bb);
4153 while (!bsi_end_p (bsi))
4155 act = bsi_stmt (bsi);
4157 bsi_insert_after (&bsi_tgt, act, BSI_NEW_STMT);
4164 /* Moves basic block BB after block AFTER. */
4167 tree_move_block_after (basic_block bb, basic_block after)
4169 if (bb->prev_bb == after)
4173 link_block (bb, after);
4179 /* Return true if basic_block can be duplicated. */
4182 tree_can_duplicate_bb_p (basic_block bb ATTRIBUTE_UNUSED)
4187 /* Create a duplicate of the basic block BB. NOTE: This does not
4188 preserve SSA form. */
4191 tree_duplicate_bb (basic_block bb)
4194 block_stmt_iterator bsi, bsi_tgt;
4196 ssa_op_iter op_iter;
4198 new_bb = create_empty_bb (EXIT_BLOCK_PTR->prev_bb);
4200 /* First copy the phi nodes. We do not copy phi node arguments here,
4201 since the edges are not ready yet. Keep the chain of phi nodes in
4202 the same order, so that we can add them later. */
4203 for (phi = phi_nodes (bb); phi; phi = TREE_CHAIN (phi))
4205 mark_for_rewrite (PHI_RESULT (phi));
4206 create_phi_node (PHI_RESULT (phi), new_bb);
4208 set_phi_nodes (new_bb, nreverse (phi_nodes (new_bb)));
4210 bsi_tgt = bsi_start (new_bb);
4211 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4213 tree stmt = bsi_stmt (bsi);
4216 if (TREE_CODE (stmt) == LABEL_EXPR)
4219 /* Record the definitions. */
4220 get_stmt_operands (stmt);
4222 FOR_EACH_SSA_TREE_OPERAND (val, stmt, op_iter, SSA_OP_ALL_DEFS)
4223 mark_for_rewrite (val);
4225 copy = unshare_expr (stmt);
4227 /* Copy also the virtual operands. */
4228 get_stmt_ann (copy);
4229 copy_virtual_operands (copy, stmt);
4231 bsi_insert_after (&bsi_tgt, copy, BSI_NEW_STMT);
4237 /* Basic block BB_COPY was created by code duplication. Add phi node
4238 arguments for edges going out of BB_COPY. The blocks that were
4239 duplicated have rbi->duplicated set to one. */
4242 add_phi_args_after_copy_bb (basic_block bb_copy)
4244 basic_block bb, dest;
4247 tree phi, phi_copy, phi_next, def;
4249 bb = bb_copy->rbi->original;
4251 FOR_EACH_EDGE (e_copy, ei, bb_copy->succs)
4253 if (!phi_nodes (e_copy->dest))
4256 if (e_copy->dest->rbi->duplicated)
4257 dest = e_copy->dest->rbi->original;
4259 dest = e_copy->dest;
4261 e = find_edge (bb, dest);
4264 /* During loop unrolling the target of the latch edge is copied.
4265 In this case we are not looking for edge to dest, but to
4266 duplicated block whose original was dest. */
4267 FOR_EACH_EDGE (e, ei, bb->succs)
4268 if (e->dest->rbi->duplicated
4269 && e->dest->rbi->original == dest)
4272 gcc_assert (e != NULL);
4275 for (phi = phi_nodes (e->dest), phi_copy = phi_nodes (e_copy->dest);
4277 phi = phi_next, phi_copy = TREE_CHAIN (phi_copy))
4279 phi_next = TREE_CHAIN (phi);
4281 gcc_assert (PHI_RESULT (phi) == PHI_RESULT (phi_copy));
4282 def = PHI_ARG_DEF_FROM_EDGE (phi, e);
4283 add_phi_arg (&phi_copy, def, e_copy);
4288 /* Blocks in REGION_COPY array of length N_REGION were created by
4289 duplication of basic blocks. Add phi node arguments for edges
4290 going from these blocks. */
4293 add_phi_args_after_copy (basic_block *region_copy, unsigned n_region)
4297 for (i = 0; i < n_region; i++)
4298 region_copy[i]->rbi->duplicated = 1;
4300 for (i = 0; i < n_region; i++)
4301 add_phi_args_after_copy_bb (region_copy[i]);
4303 for (i = 0; i < n_region; i++)
4304 region_copy[i]->rbi->duplicated = 0;
4307 /* Maps the old ssa name FROM_NAME to TO_NAME. */
4309 struct ssa_name_map_entry
4315 /* Hash function for ssa_name_map_entry. */
4318 ssa_name_map_entry_hash (const void *entry)
4320 const struct ssa_name_map_entry *en = entry;
4321 return SSA_NAME_VERSION (en->from_name);
4324 /* Equality function for ssa_name_map_entry. */
4327 ssa_name_map_entry_eq (const void *in_table, const void *ssa_name)
4329 const struct ssa_name_map_entry *en = in_table;
4331 return en->from_name == ssa_name;
4334 /* Allocate duplicates of ssa names in list DEFINITIONS and store the mapping
4338 allocate_ssa_names (bitmap definitions, htab_t *map)
4341 struct ssa_name_map_entry *entry;
4347 *map = htab_create (10, ssa_name_map_entry_hash,
4348 ssa_name_map_entry_eq, free);
4349 EXECUTE_IF_SET_IN_BITMAP (definitions, 0, ver, bi)
4351 name = ssa_name (ver);
4352 slot = htab_find_slot_with_hash (*map, name, SSA_NAME_VERSION (name),
4358 entry = xmalloc (sizeof (struct ssa_name_map_entry));
4359 entry->from_name = name;
4362 entry->to_name = duplicate_ssa_name (name, SSA_NAME_DEF_STMT (name));
4366 /* Rewrite the definition DEF in statement STMT to new ssa name as specified
4367 by the mapping MAP. */
4370 rewrite_to_new_ssa_names_def (def_operand_p def, tree stmt, htab_t map)
4372 tree name = DEF_FROM_PTR (def);
4373 struct ssa_name_map_entry *entry;
4375 gcc_assert (TREE_CODE (name) == SSA_NAME);
4377 entry = htab_find_with_hash (map, name, SSA_NAME_VERSION (name));
4381 SET_DEF (def, entry->to_name);
4382 SSA_NAME_DEF_STMT (entry->to_name) = stmt;
4385 /* Rewrite the USE to new ssa name as specified by the mapping MAP. */
4388 rewrite_to_new_ssa_names_use (use_operand_p use, htab_t map)
4390 tree name = USE_FROM_PTR (use);
4391 struct ssa_name_map_entry *entry;
4393 if (TREE_CODE (name) != SSA_NAME)
4396 entry = htab_find_with_hash (map, name, SSA_NAME_VERSION (name));
4400 SET_USE (use, entry->to_name);
4403 /* Rewrite the ssa names in basic block BB to new ones as specified by the
4407 rewrite_to_new_ssa_names_bb (basic_block bb, htab_t map)
4413 block_stmt_iterator bsi;
4417 v_may_def_optype v_may_defs;
4418 v_must_def_optype v_must_defs;
4421 FOR_EACH_EDGE (e, ei, bb->preds)
4422 if (e->flags & EDGE_ABNORMAL)
4425 for (phi = phi_nodes (bb); phi; phi = TREE_CHAIN (phi))
4427 rewrite_to_new_ssa_names_def (PHI_RESULT_PTR (phi), phi, map);
4429 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (PHI_RESULT (phi)) = 1;
4432 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4434 stmt = bsi_stmt (bsi);
4435 get_stmt_operands (stmt);
4436 ann = stmt_ann (stmt);
4438 uses = USE_OPS (ann);
4439 for (i = 0; i < NUM_USES (uses); i++)
4440 rewrite_to_new_ssa_names_use (USE_OP_PTR (uses, i), map);
4442 defs = DEF_OPS (ann);
4443 for (i = 0; i < NUM_DEFS (defs); i++)
4444 rewrite_to_new_ssa_names_def (DEF_OP_PTR (defs, i), stmt, map);
4446 vuses = VUSE_OPS (ann);
4447 for (i = 0; i < NUM_VUSES (vuses); i++)
4448 rewrite_to_new_ssa_names_use (VUSE_OP_PTR (vuses, i), map);
4450 v_may_defs = V_MAY_DEF_OPS (ann);
4451 for (i = 0; i < NUM_V_MAY_DEFS (v_may_defs); i++)
4453 rewrite_to_new_ssa_names_use
4454 (V_MAY_DEF_OP_PTR (v_may_defs, i), map);
4455 rewrite_to_new_ssa_names_def
4456 (V_MAY_DEF_RESULT_PTR (v_may_defs, i), stmt, map);
4459 v_must_defs = V_MUST_DEF_OPS (ann);
4460 for (i = 0; i < NUM_V_MUST_DEFS (v_must_defs); i++)
4461 rewrite_to_new_ssa_names_def
4462 (V_MUST_DEF_OP_PTR (v_must_defs, i), stmt, map);
4465 FOR_EACH_EDGE (e, ei, bb->succs)
4466 for (phi = phi_nodes (e->dest); phi; phi = TREE_CHAIN (phi))
4468 rewrite_to_new_ssa_names_use
4469 (PHI_ARG_DEF_PTR_FROM_EDGE (phi, e), map);
4471 if (e->flags & EDGE_ABNORMAL)
4473 tree op = PHI_ARG_DEF_FROM_EDGE (phi, e);
4474 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op) = 1;
4479 /* Rewrite the ssa names in N_REGION blocks REGION to the new ones as specified
4480 by the mapping MAP. */
4483 rewrite_to_new_ssa_names (basic_block *region, unsigned n_region, htab_t map)
4487 for (r = 0; r < n_region; r++)
4488 rewrite_to_new_ssa_names_bb (region[r], map);
4491 /* Duplicates a REGION (set of N_REGION basic blocks) with just a single
4492 important exit edge EXIT. By important we mean that no SSA name defined
4493 inside region is live over the other exit edges of the region. All entry
4494 edges to the region must go to ENTRY->dest. The edge ENTRY is redirected
4495 to the duplicate of the region. SSA form, dominance and loop information
4496 is updated. The new basic blocks are stored to REGION_COPY in the same
4497 order as they had in REGION, provided that REGION_COPY is not NULL.
4498 The function returns false if it is unable to copy the region,
4502 tree_duplicate_sese_region (edge entry, edge exit,
4503 basic_block *region, unsigned n_region,
4504 basic_block *region_copy)
4506 unsigned i, n_doms, ver;
4507 bool free_region_copy = false, copying_header = false;
4508 struct loop *loop = entry->dest->loop_father;
4513 htab_t ssa_name_map = NULL;
4517 if (!can_copy_bbs_p (region, n_region))
4520 /* Some sanity checking. Note that we do not check for all possible
4521 missuses of the functions. I.e. if you ask to copy something weird,
4522 it will work, but the state of structures probably will not be
4525 for (i = 0; i < n_region; i++)
4527 /* We do not handle subloops, i.e. all the blocks must belong to the
4529 if (region[i]->loop_father != loop)
4532 if (region[i] != entry->dest
4533 && region[i] == loop->header)
4539 /* In case the function is used for loop header copying (which is the primary
4540 use), ensure that EXIT and its copy will be new latch and entry edges. */
4541 if (loop->header == entry->dest)
4543 copying_header = true;
4544 loop->copy = loop->outer;
4546 if (!dominated_by_p (CDI_DOMINATORS, loop->latch, exit->src))
4549 for (i = 0; i < n_region; i++)
4550 if (region[i] != exit->src
4551 && dominated_by_p (CDI_DOMINATORS, region[i], exit->src))
4557 region_copy = xmalloc (sizeof (basic_block) * n_region);
4558 free_region_copy = true;
4561 gcc_assert (!any_marked_for_rewrite_p ());
4563 /* Record blocks outside the region that are duplicated by something
4565 doms = xmalloc (sizeof (basic_block) * n_basic_blocks);
4566 n_doms = get_dominated_by_region (CDI_DOMINATORS, region, n_region, doms);
4568 copy_bbs (region, n_region, region_copy, &exit, 1, &exit_copy, loop);
4569 definitions = marked_ssa_names ();
4573 loop->header = exit->dest;
4574 loop->latch = exit->src;
4577 /* Redirect the entry and add the phi node arguments. */
4578 redirected = redirect_edge_and_branch (entry, entry->dest->rbi->copy);
4579 gcc_assert (redirected != NULL);
4580 for (phi = phi_nodes (entry->dest), var = PENDING_STMT (entry);
4582 phi = TREE_CHAIN (phi), var = TREE_CHAIN (var))
4583 add_phi_arg (&phi, TREE_VALUE (var), entry);
4584 PENDING_STMT (entry) = NULL;
4586 /* Concerning updating of dominators: We must recount dominators
4587 for entry block and its copy. Anything that is outside of the region, but
4588 was dominated by something inside needs recounting as well. */
4589 set_immediate_dominator (CDI_DOMINATORS, entry->dest, entry->src);
4590 doms[n_doms++] = entry->dest->rbi->original;
4591 iterate_fix_dominators (CDI_DOMINATORS, doms, n_doms);
4594 /* Add the other phi node arguments. */
4595 add_phi_args_after_copy (region_copy, n_region);
4597 /* Add phi nodes for definitions at exit. TODO -- once we have immediate
4598 uses, it should be possible to emit phi nodes just for definitions that
4599 are used outside region. */
4600 EXECUTE_IF_SET_IN_BITMAP (definitions, 0, ver, bi)
4602 tree name = ssa_name (ver);
4604 phi = create_phi_node (name, exit->dest);
4605 add_phi_arg (&phi, name, exit);
4606 add_phi_arg (&phi, name, exit_copy);
4608 SSA_NAME_DEF_STMT (name) = phi;
4611 /* And create new definitions inside region and its copy. TODO -- once we
4612 have immediate uses, it might be better to leave definitions in region
4613 unchanged, create new ssa names for phi nodes on exit, and rewrite
4614 the uses, to avoid changing the copied region. */
4615 allocate_ssa_names (definitions, &ssa_name_map);
4616 rewrite_to_new_ssa_names (region, n_region, ssa_name_map);
4617 allocate_ssa_names (definitions, &ssa_name_map);
4618 rewrite_to_new_ssa_names (region_copy, n_region, ssa_name_map);
4619 htab_delete (ssa_name_map);
4621 if (free_region_copy)
4624 unmark_all_for_rewrite ();
4625 BITMAP_XFREE (definitions);
4630 /* Dump FUNCTION_DECL FN to file FILE using FLAGS (see TDF_* in tree.h) */
4633 dump_function_to_file (tree fn, FILE *file, int flags)
4635 tree arg, vars, var;
4636 bool ignore_topmost_bind = false, any_var = false;
4640 fprintf (file, "%s (", lang_hooks.decl_printable_name (fn, 2));
4642 arg = DECL_ARGUMENTS (fn);
4645 print_generic_expr (file, arg, dump_flags);
4646 if (TREE_CHAIN (arg))
4647 fprintf (file, ", ");
4648 arg = TREE_CHAIN (arg);
4650 fprintf (file, ")\n");
4652 if (flags & TDF_RAW)
4654 dump_node (fn, TDF_SLIM | flags, file);
4658 /* When GIMPLE is lowered, the variables are no longer available in
4659 BIND_EXPRs, so display them separately. */
4660 if (cfun && cfun->unexpanded_var_list)
4662 ignore_topmost_bind = true;
4664 fprintf (file, "{\n");
4665 for (vars = cfun->unexpanded_var_list; vars; vars = TREE_CHAIN (vars))
4667 var = TREE_VALUE (vars);
4669 print_generic_decl (file, var, flags);
4670 fprintf (file, "\n");
4676 if (basic_block_info)
4678 /* Make a CFG based dump. */
4679 check_bb_profile (ENTRY_BLOCK_PTR, file);
4680 if (!ignore_topmost_bind)
4681 fprintf (file, "{\n");
4683 if (any_var && n_basic_blocks)
4684 fprintf (file, "\n");
4687 dump_generic_bb (file, bb, 2, flags);
4689 fprintf (file, "}\n");
4690 check_bb_profile (EXIT_BLOCK_PTR, file);
4696 /* Make a tree based dump. */
4697 chain = DECL_SAVED_TREE (fn);
4699 if (TREE_CODE (chain) == BIND_EXPR)
4701 if (ignore_topmost_bind)
4703 chain = BIND_EXPR_BODY (chain);
4711 if (!ignore_topmost_bind)
4712 fprintf (file, "{\n");
4717 fprintf (file, "\n");
4719 print_generic_stmt_indented (file, chain, flags, indent);
4720 if (ignore_topmost_bind)
4721 fprintf (file, "}\n");
4724 fprintf (file, "\n\n");
4728 /* Pretty print of the loops intermediate representation. */
4729 static void print_loop (FILE *, struct loop *, int);
4730 static void print_pred_bbs (FILE *, basic_block bb);
4731 static void print_succ_bbs (FILE *, basic_block bb);
4734 /* Print the predecessors indexes of edge E on FILE. */
4737 print_pred_bbs (FILE *file, basic_block bb)
4742 FOR_EACH_EDGE (e, ei, bb->preds)
4743 fprintf (file, "bb_%d", e->src->index);
4747 /* Print the successors indexes of edge E on FILE. */
4750 print_succ_bbs (FILE *file, basic_block bb)
4755 FOR_EACH_EDGE (e, ei, bb->succs)
4756 fprintf (file, "bb_%d", e->src->index);
4760 /* Pretty print LOOP on FILE, indented INDENT spaces. */
4763 print_loop (FILE *file, struct loop *loop, int indent)
4771 s_indent = (char *) alloca ((size_t) indent + 1);
4772 memset ((void *) s_indent, ' ', (size_t) indent);
4773 s_indent[indent] = '\0';
4775 /* Print the loop's header. */
4776 fprintf (file, "%sloop_%d\n", s_indent, loop->num);
4778 /* Print the loop's body. */
4779 fprintf (file, "%s{\n", s_indent);
4781 if (bb->loop_father == loop)
4783 /* Print the basic_block's header. */
4784 fprintf (file, "%s bb_%d (preds = {", s_indent, bb->index);
4785 print_pred_bbs (file, bb);
4786 fprintf (file, "}, succs = {");
4787 print_succ_bbs (file, bb);
4788 fprintf (file, "})\n");
4790 /* Print the basic_block's body. */
4791 fprintf (file, "%s {\n", s_indent);
4792 tree_dump_bb (bb, file, indent + 4);
4793 fprintf (file, "%s }\n", s_indent);
4796 print_loop (file, loop->inner, indent + 2);
4797 fprintf (file, "%s}\n", s_indent);
4798 print_loop (file, loop->next, indent);
4802 /* Follow a CFG edge from the entry point of the program, and on entry
4803 of a loop, pretty print the loop structure on FILE. */
4806 print_loop_ir (FILE *file)
4810 bb = BASIC_BLOCK (0);
4811 if (bb && bb->loop_father)
4812 print_loop (file, bb->loop_father, 0);
4816 /* Debugging loops structure at tree level. */
4819 debug_loop_ir (void)
4821 print_loop_ir (stderr);
4825 /* Return true if BB ends with a call, possibly followed by some
4826 instructions that must stay with the call. Return false,
4830 tree_block_ends_with_call_p (basic_block bb)
4832 block_stmt_iterator bsi = bsi_last (bb);
4833 return get_call_expr_in (bsi_stmt (bsi)) != NULL;
4837 /* Return true if BB ends with a conditional branch. Return false,
4841 tree_block_ends_with_condjump_p (basic_block bb)
4843 tree stmt = tsi_stmt (bsi_last (bb).tsi);
4844 return (TREE_CODE (stmt) == COND_EXPR);
4848 /* Return true if we need to add fake edge to exit at statement T.
4849 Helper function for tree_flow_call_edges_add. */
4852 need_fake_edge_p (tree t)
4856 /* NORETURN and LONGJMP calls already have an edge to exit.
4857 CONST, PURE and ALWAYS_RETURN calls do not need one.
4858 We don't currently check for CONST and PURE here, although
4859 it would be a good idea, because those attributes are
4860 figured out from the RTL in mark_constant_function, and
4861 the counter incrementation code from -fprofile-arcs
4862 leads to different results from -fbranch-probabilities. */
4863 call = get_call_expr_in (t);
4865 && !(call_expr_flags (call) &
4866 (ECF_NORETURN | ECF_LONGJMP | ECF_ALWAYS_RETURN)))
4869 if (TREE_CODE (t) == ASM_EXPR
4870 && (ASM_VOLATILE_P (t) || ASM_INPUT_P (t)))
4877 /* Add fake edges to the function exit for any non constant and non
4878 noreturn calls, volatile inline assembly in the bitmap of blocks
4879 specified by BLOCKS or to the whole CFG if BLOCKS is zero. Return
4880 the number of blocks that were split.
4882 The goal is to expose cases in which entering a basic block does
4883 not imply that all subsequent instructions must be executed. */
4886 tree_flow_call_edges_add (sbitmap blocks)
4889 int blocks_split = 0;
4890 int last_bb = last_basic_block;
4891 bool check_last_block = false;
4893 if (n_basic_blocks == 0)
4897 check_last_block = true;
4899 check_last_block = TEST_BIT (blocks, EXIT_BLOCK_PTR->prev_bb->index);
4901 /* In the last basic block, before epilogue generation, there will be
4902 a fallthru edge to EXIT. Special care is required if the last insn
4903 of the last basic block is a call because make_edge folds duplicate
4904 edges, which would result in the fallthru edge also being marked
4905 fake, which would result in the fallthru edge being removed by
4906 remove_fake_edges, which would result in an invalid CFG.
4908 Moreover, we can't elide the outgoing fake edge, since the block
4909 profiler needs to take this into account in order to solve the minimal
4910 spanning tree in the case that the call doesn't return.
4912 Handle this by adding a dummy instruction in a new last basic block. */
4913 if (check_last_block)
4916 basic_block bb = EXIT_BLOCK_PTR->prev_bb;
4917 block_stmt_iterator bsi = bsi_last (bb);
4919 if (!bsi_end_p (bsi))
4922 if (need_fake_edge_p (t))
4926 FOR_EACH_EDGE (e, ei, bb->succs)
4927 if (e->dest == EXIT_BLOCK_PTR)
4929 bsi_insert_on_edge (e, build_empty_stmt ());
4930 bsi_commit_edge_inserts ((int *)NULL);
4936 /* Now add fake edges to the function exit for any non constant
4937 calls since there is no way that we can determine if they will
4939 for (i = 0; i < last_bb; i++)
4941 basic_block bb = BASIC_BLOCK (i);
4942 block_stmt_iterator bsi;
4943 tree stmt, last_stmt;
4948 if (blocks && !TEST_BIT (blocks, i))
4951 bsi = bsi_last (bb);
4952 if (!bsi_end_p (bsi))
4954 last_stmt = bsi_stmt (bsi);
4957 stmt = bsi_stmt (bsi);
4958 if (need_fake_edge_p (stmt))
4961 /* The handling above of the final block before the
4962 epilogue should be enough to verify that there is
4963 no edge to the exit block in CFG already.
4964 Calling make_edge in such case would cause us to
4965 mark that edge as fake and remove it later. */
4966 #ifdef ENABLE_CHECKING
4967 if (stmt == last_stmt)
4970 FOR_EACH_EDGE (e, ei, bb->succs)
4971 gcc_assert (e->dest != EXIT_BLOCK_PTR);
4975 /* Note that the following may create a new basic block
4976 and renumber the existing basic blocks. */
4977 if (stmt != last_stmt)
4979 e = split_block (bb, stmt);
4983 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
4987 while (!bsi_end_p (bsi));
4992 verify_flow_info ();
4994 return blocks_split;
4998 tree_purge_dead_eh_edges (basic_block bb)
5000 bool changed = false;
5003 tree stmt = last_stmt (bb);
5005 if (stmt && tree_can_throw_internal (stmt))
5008 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
5010 if (e->flags & EDGE_EH)
5012 ssa_remove_edge (e);
5019 /* Removal of dead EH edges might change dominators of not
5020 just immediate successors. E.g. when bb1 is changed so that
5021 it no longer can throw and bb1->bb3 and bb1->bb4 are dead
5022 eh edges purged by this function in:
5034 idom(bb5) must be recomputed. For now just free the dominance
5037 free_dominance_info (CDI_DOMINATORS);
5043 tree_purge_all_dead_eh_edges (bitmap blocks)
5045 bool changed = false;
5049 EXECUTE_IF_SET_IN_BITMAP (blocks, 0, i, bi)
5051 changed |= tree_purge_dead_eh_edges (BASIC_BLOCK (i));
5057 struct cfg_hooks tree_cfg_hooks = {
5059 tree_verify_flow_info,
5060 tree_dump_bb, /* dump_bb */
5061 create_bb, /* create_basic_block */
5062 tree_redirect_edge_and_branch,/* redirect_edge_and_branch */
5063 tree_redirect_edge_and_branch_force,/* redirect_edge_and_branch_force */
5064 remove_bb, /* delete_basic_block */
5065 tree_split_block, /* split_block */
5066 tree_move_block_after, /* move_block_after */
5067 tree_can_merge_blocks_p, /* can_merge_blocks_p */
5068 tree_merge_blocks, /* merge_blocks */
5069 tree_predict_edge, /* predict_edge */
5070 tree_predicted_by_p, /* predicted_by_p */
5071 tree_can_duplicate_bb_p, /* can_duplicate_block_p */
5072 tree_duplicate_bb, /* duplicate_block */
5073 tree_split_edge, /* split_edge */
5074 tree_make_forwarder_block, /* make_forward_block */
5075 NULL, /* tidy_fallthru_edge */
5076 tree_block_ends_with_call_p, /* block_ends_with_call_p */
5077 tree_block_ends_with_condjump_p, /* block_ends_with_condjump_p */
5078 tree_flow_call_edges_add /* flow_call_edges_add */
5082 /* Split all critical edges. */
5085 split_critical_edges (void)
5093 FOR_EACH_EDGE (e, ei, bb->succs)
5094 if (EDGE_CRITICAL_P (e) && !(e->flags & EDGE_ABNORMAL))
5101 struct tree_opt_pass pass_split_crit_edges =
5103 "crited", /* name */
5105 split_critical_edges, /* execute */
5108 0, /* static_pass_number */
5109 TV_TREE_SPLIT_EDGES, /* tv_id */
5110 PROP_cfg, /* properties required */
5111 PROP_no_crit_edges, /* properties_provided */
5112 0, /* properties_destroyed */
5113 0, /* todo_flags_start */
5114 TODO_dump_func, /* todo_flags_finish */
5119 /* Return EXP if it is a valid GIMPLE rvalue, else gimplify it into
5120 a temporary, make sure and register it to be renamed if necessary,
5121 and finally return the temporary. Put the statements to compute
5122 EXP before the current statement in BSI. */
5125 gimplify_val (block_stmt_iterator *bsi, tree type, tree exp)
5127 tree t, new_stmt, orig_stmt;
5129 if (is_gimple_val (exp))
5132 t = make_rename_temp (type, NULL);
5133 new_stmt = build (MODIFY_EXPR, type, t, exp);
5135 orig_stmt = bsi_stmt (*bsi);
5136 SET_EXPR_LOCUS (new_stmt, EXPR_LOCUS (orig_stmt));
5137 TREE_BLOCK (new_stmt) = TREE_BLOCK (orig_stmt);
5139 bsi_insert_before (bsi, new_stmt, BSI_SAME_STMT);
5144 /* Build a ternary operation and gimplify it. Emit code before BSI.
5145 Return the gimple_val holding the result. */
5148 gimplify_build3 (block_stmt_iterator *bsi, enum tree_code code,
5149 tree type, tree a, tree b, tree c)
5153 ret = fold (build3 (code, type, a, b, c));
5156 return gimplify_val (bsi, type, ret);
5159 /* Build a binary operation and gimplify it. Emit code before BSI.
5160 Return the gimple_val holding the result. */
5163 gimplify_build2 (block_stmt_iterator *bsi, enum tree_code code,
5164 tree type, tree a, tree b)
5168 ret = fold (build2 (code, type, a, b));
5171 return gimplify_val (bsi, type, ret);
5174 /* Build a unary operation and gimplify it. Emit code before BSI.
5175 Return the gimple_val holding the result. */
5178 gimplify_build1 (block_stmt_iterator *bsi, enum tree_code code, tree type,
5183 ret = fold (build1 (code, type, a));
5186 return gimplify_val (bsi, type, ret);
5191 /* Emit return warnings. */
5194 execute_warn_function_return (void)
5196 #ifdef USE_MAPPED_LOCATION
5197 source_location location;
5205 if (warn_missing_noreturn
5206 && !TREE_THIS_VOLATILE (cfun->decl)
5207 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) == 0
5208 && !lang_hooks.function.missing_noreturn_ok_p (cfun->decl))
5209 warning ("%Jfunction might be possible candidate for "
5210 "attribute %<noreturn%>",
5213 /* If we have a path to EXIT, then we do return. */
5214 if (TREE_THIS_VOLATILE (cfun->decl)
5215 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) > 0)
5217 #ifdef USE_MAPPED_LOCATION
5218 location = UNKNOWN_LOCATION;
5222 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
5224 last = last_stmt (e->src);
5225 if (TREE_CODE (last) == RETURN_EXPR
5226 #ifdef USE_MAPPED_LOCATION
5227 && (location = EXPR_LOCATION (last)) != UNKNOWN_LOCATION)
5229 && (locus = EXPR_LOCUS (last)) != NULL)
5233 #ifdef USE_MAPPED_LOCATION
5234 if (location == UNKNOWN_LOCATION)
5235 location = cfun->function_end_locus;
5236 warning ("%H%<noreturn%> function does return", &location);
5239 locus = &cfun->function_end_locus;
5240 warning ("%H%<noreturn%> function does return", locus);
5244 /* If we see "return;" in some basic block, then we do reach the end
5245 without returning a value. */
5246 else if (warn_return_type
5247 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) > 0
5248 && !VOID_TYPE_P (TREE_TYPE (TREE_TYPE (cfun->decl))))
5250 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
5252 tree last = last_stmt (e->src);
5253 if (TREE_CODE (last) == RETURN_EXPR
5254 && TREE_OPERAND (last, 0) == NULL)
5256 #ifdef USE_MAPPED_LOCATION
5257 location = EXPR_LOCATION (last);
5258 if (location == UNKNOWN_LOCATION)
5259 location = cfun->function_end_locus;
5260 warning ("%Hcontrol reaches end of non-void function", &location);
5262 locus = EXPR_LOCUS (last);
5264 locus = &cfun->function_end_locus;
5265 warning ("%Hcontrol reaches end of non-void function", locus);
5274 /* Given a basic block B which ends with a conditional and has
5275 precisely two successors, determine which of the edges is taken if
5276 the conditional is true and which is taken if the conditional is
5277 false. Set TRUE_EDGE and FALSE_EDGE appropriately. */
5280 extract_true_false_edges_from_block (basic_block b,
5284 edge e = EDGE_SUCC (b, 0);
5286 if (e->flags & EDGE_TRUE_VALUE)
5289 *false_edge = EDGE_SUCC (b, 1);
5294 *true_edge = EDGE_SUCC (b, 1);
5298 struct tree_opt_pass pass_warn_function_return =
5302 execute_warn_function_return, /* execute */
5305 0, /* static_pass_number */
5307 PROP_cfg, /* properties_required */
5308 0, /* properties_provided */
5309 0, /* properties_destroyed */
5310 0, /* todo_flags_start */
5311 0, /* todo_flags_finish */
5315 #include "gt-tree-cfg.h"