1 /* Control flow functions for trees.
2 Copyright (C) 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
3 Contributed by Diego Novillo <dnovillo@redhat.com>
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 GCC is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to
19 the Free Software Foundation, 59 Temple Place - Suite 330,
20 Boston, MA 02111-1307, USA. */
24 #include "coretypes.h"
29 #include "hard-reg-set.h"
30 #include "basic-block.h"
37 #include "langhooks.h"
38 #include "diagnostic.h"
39 #include "tree-flow.h"
41 #include "tree-dump.h"
42 #include "tree-pass.h"
46 #include "cfglayout.h"
48 /* This file contains functions for building the Control Flow Graph (CFG)
49 for a function tree. */
51 /* Local declarations. */
53 /* Initial capacity for the basic block array. */
54 static const int initial_cfg_capacity = 20;
56 /* Mapping of labels to their associated blocks. This can greatly speed up
57 building of the CFG in code with lots of gotos. */
58 static GTY(()) varray_type label_to_block_map;
63 long num_merged_labels;
66 static struct cfg_stats_d cfg_stats;
68 /* Nonzero if we found a computed goto while building basic blocks. */
69 static bool found_computed_goto;
71 /* Basic blocks and flowgraphs. */
72 static basic_block create_bb (void *, void *, basic_block);
73 static void create_block_annotation (basic_block);
74 static void free_blocks_annotations (void);
75 static void clear_blocks_annotations (void);
76 static void make_blocks (tree);
77 static void factor_computed_gotos (void);
80 static void make_edges (void);
81 static void make_ctrl_stmt_edges (basic_block);
82 static void make_exit_edges (basic_block);
83 static void make_cond_expr_edges (basic_block);
84 static void make_switch_expr_edges (basic_block);
85 static void make_goto_expr_edges (basic_block);
86 static edge tree_redirect_edge_and_branch (edge, basic_block);
87 static edge tree_try_redirect_by_replacing_jump (edge, basic_block);
88 static void split_critical_edges (void);
90 /* Various helpers. */
91 static inline bool stmt_starts_bb_p (tree, tree);
92 static int tree_verify_flow_info (void);
93 static void tree_make_forwarder_block (edge);
94 static bool thread_jumps (void);
95 static bool tree_forwarder_block_p (basic_block);
96 static void bsi_commit_edge_inserts_1 (edge e);
97 static void tree_cfg2vcg (FILE *);
99 /* Flowgraph optimization and cleanup. */
100 static void tree_merge_blocks (basic_block, basic_block);
101 static bool tree_can_merge_blocks_p (basic_block, basic_block);
102 static void remove_bb (basic_block);
103 static bool cleanup_control_flow (void);
104 static bool cleanup_control_expr_graph (basic_block, block_stmt_iterator);
105 static edge find_taken_edge_cond_expr (basic_block, tree);
106 static edge find_taken_edge_switch_expr (basic_block, tree);
107 static tree find_case_label_for_value (tree, tree);
108 static bool phi_alternatives_equal (basic_block, edge, edge);
111 /*---------------------------------------------------------------------------
113 ---------------------------------------------------------------------------*/
115 /* Entry point to the CFG builder for trees. TP points to the list of
116 statements to be added to the flowgraph. */
119 build_tree_cfg (tree *tp)
121 /* Register specific tree functions. */
122 tree_register_cfg_hooks ();
124 /* Initialize rbi_pool. */
127 /* Initialize the basic block array. */
129 profile_status = PROFILE_ABSENT;
131 last_basic_block = 0;
132 VARRAY_BB_INIT (basic_block_info, initial_cfg_capacity, "basic_block_info");
133 memset ((void *) &cfg_stats, 0, sizeof (cfg_stats));
135 /* Build a mapping of labels to their associated blocks. */
136 VARRAY_BB_INIT (label_to_block_map, initial_cfg_capacity,
137 "label to block map");
139 ENTRY_BLOCK_PTR->next_bb = EXIT_BLOCK_PTR;
140 EXIT_BLOCK_PTR->prev_bb = ENTRY_BLOCK_PTR;
142 found_computed_goto = 0;
145 /* Computed gotos are hell to deal with, especially if there are
146 lots of them with a large number of destinations. So we factor
147 them to a common computed goto location before we build the
148 edge list. After we convert back to normal form, we will un-factor
149 the computed gotos since factoring introduces an unwanted jump. */
150 if (found_computed_goto)
151 factor_computed_gotos ();
153 /* Make sure there is always at least one block, even if its empty. */
154 if (n_basic_blocks == 0)
155 create_empty_bb (ENTRY_BLOCK_PTR);
157 create_block_annotation (ENTRY_BLOCK_PTR);
158 create_block_annotation (EXIT_BLOCK_PTR);
160 /* Adjust the size of the array. */
161 VARRAY_GROW (basic_block_info, n_basic_blocks);
163 /* To speed up statement iterator walks, we first purge dead labels. */
164 cleanup_dead_labels ();
166 /* Group case nodes to reduce the number of edges.
167 We do this after cleaning up dead labels because otherwise we miss
168 a lot of obvious case merging opportunities. */
169 group_case_labels ();
171 /* Create the edges of the flowgraph. */
174 /* Debugging dumps. */
176 /* Write the flowgraph to a VCG file. */
178 int local_dump_flags;
179 FILE *dump_file = dump_begin (TDI_vcg, &local_dump_flags);
182 tree_cfg2vcg (dump_file);
183 dump_end (TDI_vcg, dump_file);
187 /* Dump a textual representation of the flowgraph. */
189 dump_tree_cfg (dump_file, dump_flags);
193 execute_build_cfg (void)
195 build_tree_cfg (&DECL_SAVED_TREE (current_function_decl));
198 struct tree_opt_pass pass_build_cfg =
202 execute_build_cfg, /* execute */
205 0, /* static_pass_number */
206 TV_TREE_CFG, /* tv_id */
207 PROP_gimple_leh, /* properties_required */
208 PROP_cfg, /* properties_provided */
209 0, /* properties_destroyed */
210 0, /* todo_flags_start */
211 TODO_verify_stmts, /* todo_flags_finish */
215 /* Search the CFG for any computed gotos. If found, factor them to a
216 common computed goto site. Also record the location of that site so
217 that we can un-factor the gotos after we have converted back to
221 factor_computed_gotos (void)
224 tree factored_label_decl = NULL;
226 tree factored_computed_goto_label = NULL;
227 tree factored_computed_goto = NULL;
229 /* We know there are one or more computed gotos in this function.
230 Examine the last statement in each basic block to see if the block
231 ends with a computed goto. */
235 block_stmt_iterator bsi = bsi_last (bb);
240 last = bsi_stmt (bsi);
242 /* Ignore the computed goto we create when we factor the original
244 if (last == factored_computed_goto)
247 /* If the last statement is a computed goto, factor it. */
248 if (computed_goto_p (last))
252 /* The first time we find a computed goto we need to create
253 the factored goto block and the variable each original
254 computed goto will use for their goto destination. */
255 if (! factored_computed_goto)
257 basic_block new_bb = create_empty_bb (bb);
258 block_stmt_iterator new_bsi = bsi_start (new_bb);
260 /* Create the destination of the factored goto. Each original
261 computed goto will put its desired destination into this
262 variable and jump to the label we create immediately
264 var = create_tmp_var (ptr_type_node, "gotovar");
266 /* Build a label for the new block which will contain the
267 factored computed goto. */
268 factored_label_decl = create_artificial_label ();
269 factored_computed_goto_label
270 = build1 (LABEL_EXPR, void_type_node, factored_label_decl);
271 bsi_insert_after (&new_bsi, factored_computed_goto_label,
274 /* Build our new computed goto. */
275 factored_computed_goto = build1 (GOTO_EXPR, void_type_node, var);
276 bsi_insert_after (&new_bsi, factored_computed_goto,
280 /* Copy the original computed goto's destination into VAR. */
281 assignment = build (MODIFY_EXPR, ptr_type_node,
282 var, GOTO_DESTINATION (last));
283 bsi_insert_before (&bsi, assignment, BSI_SAME_STMT);
285 /* And re-vector the computed goto to the new destination. */
286 GOTO_DESTINATION (last) = factored_label_decl;
292 /* Create annotations for a single basic block. */
295 create_block_annotation (basic_block bb)
297 /* Verify that the tree_annotations field is clear. */
298 gcc_assert (!bb->tree_annotations);
299 bb->tree_annotations = ggc_alloc_cleared (sizeof (struct bb_ann_d));
303 /* Free the annotations for all the basic blocks. */
305 static void free_blocks_annotations (void)
307 clear_blocks_annotations ();
311 /* Clear the annotations for all the basic blocks. */
314 clear_blocks_annotations (void)
318 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb)
319 bb->tree_annotations = NULL;
323 /* Build a flowgraph for the statement_list STMT_LIST. */
326 make_blocks (tree stmt_list)
328 tree_stmt_iterator i = tsi_start (stmt_list);
330 bool start_new_block = true;
331 bool first_stmt_of_list = true;
332 basic_block bb = ENTRY_BLOCK_PTR;
334 while (!tsi_end_p (i))
341 /* If the statement starts a new basic block or if we have determined
342 in a previous pass that we need to create a new block for STMT, do
344 if (start_new_block || stmt_starts_bb_p (stmt, prev_stmt))
346 if (!first_stmt_of_list)
347 stmt_list = tsi_split_statement_list_before (&i);
348 bb = create_basic_block (stmt_list, NULL, bb);
349 start_new_block = false;
352 /* Now add STMT to BB and create the subgraphs for special statement
354 set_bb_for_stmt (stmt, bb);
356 if (computed_goto_p (stmt))
357 found_computed_goto = true;
359 /* If STMT is a basic block terminator, set START_NEW_BLOCK for the
361 if (stmt_ends_bb_p (stmt))
362 start_new_block = true;
365 first_stmt_of_list = false;
370 /* Create and return a new empty basic block after bb AFTER. */
373 create_bb (void *h, void *e, basic_block after)
379 /* Create and initialize a new basic block. */
381 memset (bb, 0, sizeof (*bb));
383 bb->index = last_basic_block;
385 bb->stmt_list = h ? h : alloc_stmt_list ();
387 /* Add the new block to the linked list of blocks. */
388 link_block (bb, after);
390 /* Grow the basic block array if needed. */
391 if ((size_t) last_basic_block == VARRAY_SIZE (basic_block_info))
393 size_t new_size = last_basic_block + (last_basic_block + 3) / 4;
394 VARRAY_GROW (basic_block_info, new_size);
397 /* Add the newly created block to the array. */
398 BASIC_BLOCK (last_basic_block) = bb;
400 create_block_annotation (bb);
405 initialize_bb_rbi (bb);
410 /*---------------------------------------------------------------------------
412 ---------------------------------------------------------------------------*/
414 /* Join all the blocks in the flowgraph. */
421 /* Create an edge from entry to the first block with executable
423 make_edge (ENTRY_BLOCK_PTR, BASIC_BLOCK (0), EDGE_FALLTHRU);
425 /* Traverse basic block array placing edges. */
428 tree first = first_stmt (bb);
429 tree last = last_stmt (bb);
433 /* Edges for statements that always alter flow control. */
434 if (is_ctrl_stmt (last))
435 make_ctrl_stmt_edges (bb);
437 /* Edges for statements that sometimes alter flow control. */
438 if (is_ctrl_altering_stmt (last))
439 make_exit_edges (bb);
442 /* Finally, if no edges were created above, this is a regular
443 basic block that only needs a fallthru edge. */
444 if (bb->succ == NULL)
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 (bb->succ == NULL)
487 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
496 /* Create exit edges for statements in block BB that alter the flow of
497 control. Statements that alter the control flow are 'goto', 'return'
498 and calls to non-returning functions. */
501 make_exit_edges (basic_block bb)
503 tree last = last_stmt (bb), op;
506 switch (TREE_CODE (last))
509 /* If this function receives a nonlocal goto, then we need to
510 make edges from this call site to all the nonlocal goto
512 if (TREE_SIDE_EFFECTS (last)
513 && current_function_has_nonlocal_label)
514 make_goto_expr_edges (bb);
516 /* If this statement has reachable exception handlers, then
517 create abnormal edges to them. */
518 make_eh_edges (last);
520 /* Some calls are known not to return. For such calls we create
523 We really need to revamp how we build edges so that it's not
524 such a bloody pain to avoid creating edges for this case since
525 all we do is remove these edges when we're done building the
527 if (call_expr_flags (last) & (ECF_NORETURN | ECF_LONGJMP))
529 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
533 /* Don't forget the fall-thru edge. */
534 make_edge (bb, bb->next_bb, EDGE_FALLTHRU);
538 /* A MODIFY_EXPR may have a CALL_EXPR on its RHS and the CALL_EXPR
539 may have an abnormal edge. Search the RHS for this case and
540 create any required edges. */
541 op = get_call_expr_in (last);
542 if (op && TREE_SIDE_EFFECTS (op)
543 && current_function_has_nonlocal_label)
544 make_goto_expr_edges (bb);
546 make_eh_edges (last);
547 make_edge (bb, bb->next_bb, EDGE_FALLTHRU);
556 /* Create the edges for a COND_EXPR starting at block BB.
557 At this point, both clauses must contain only simple gotos. */
560 make_cond_expr_edges (basic_block bb)
562 tree entry = last_stmt (bb);
563 basic_block then_bb, else_bb;
564 tree then_label, else_label;
567 gcc_assert (TREE_CODE (entry) == COND_EXPR);
569 /* Entry basic blocks for each component. */
570 then_label = GOTO_DESTINATION (COND_EXPR_THEN (entry));
571 else_label = GOTO_DESTINATION (COND_EXPR_ELSE (entry));
572 then_bb = label_to_block (then_label);
573 else_bb = label_to_block (else_label);
575 make_edge (bb, then_bb, EDGE_TRUE_VALUE);
576 make_edge (bb, else_bb, EDGE_FALSE_VALUE);
580 /* Create the edges for a SWITCH_EXPR starting at block BB.
581 At this point, the switch body has been lowered and the
582 SWITCH_LABELS filled in, so this is in effect a multi-way branch. */
585 make_switch_expr_edges (basic_block bb)
587 tree entry = last_stmt (bb);
591 vec = SWITCH_LABELS (entry);
592 n = TREE_VEC_LENGTH (vec);
594 for (i = 0; i < n; ++i)
596 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
597 basic_block label_bb = label_to_block (lab);
598 make_edge (bb, label_bb, 0);
603 /* Return the basic block holding label DEST. */
606 label_to_block (tree dest)
608 int uid = LABEL_DECL_UID (dest);
610 /* We would die hard when faced by undefined label. Emit label to
611 very first basic block. This will hopefully make even the dataflow
612 and undefined variable warnings quite right. */
613 if ((errorcount || sorrycount) && uid < 0)
615 block_stmt_iterator bsi = bsi_start (BASIC_BLOCK (0));
618 stmt = build1 (LABEL_EXPR, void_type_node, dest);
619 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
620 uid = LABEL_DECL_UID (dest);
622 return VARRAY_BB (label_to_block_map, uid);
626 /* Create edges for a goto statement at block BB. */
629 make_goto_expr_edges (basic_block bb)
632 basic_block target_bb;
634 block_stmt_iterator last = bsi_last (bb);
636 goto_t = bsi_stmt (last);
638 /* If the last statement is not a GOTO (i.e., it is a RETURN_EXPR,
639 CALL_EXPR or MODIFY_EXPR), then the edge is an abnormal edge resulting
640 from a nonlocal goto. */
641 if (TREE_CODE (goto_t) != GOTO_EXPR)
643 dest = error_mark_node;
648 dest = GOTO_DESTINATION (goto_t);
651 /* A GOTO to a local label creates normal edges. */
652 if (simple_goto_p (goto_t))
654 edge e = make_edge (bb, label_to_block (dest), EDGE_FALLTHRU);
655 #ifdef USE_MAPPED_LOCATION
656 e->goto_locus = EXPR_LOCATION (goto_t);
658 e->goto_locus = EXPR_LOCUS (goto_t);
664 /* Nothing more to do for nonlocal gotos. */
665 if (TREE_CODE (dest) == LABEL_DECL)
668 /* Computed gotos remain. */
671 /* Look for the block starting with the destination label. In the
672 case of a computed goto, make an edge to any label block we find
674 FOR_EACH_BB (target_bb)
676 block_stmt_iterator bsi;
678 for (bsi = bsi_start (target_bb); !bsi_end_p (bsi); bsi_next (&bsi))
680 tree target = bsi_stmt (bsi);
682 if (TREE_CODE (target) != LABEL_EXPR)
686 /* Computed GOTOs. Make an edge to every label block that has
687 been marked as a potential target for a computed goto. */
688 (FORCED_LABEL (LABEL_EXPR_LABEL (target)) && for_call == 0)
689 /* Nonlocal GOTO target. Make an edge to every label block
690 that has been marked as a potential target for a nonlocal
692 || (DECL_NONLOCAL (LABEL_EXPR_LABEL (target)) && for_call == 1))
694 make_edge (bb, target_bb, EDGE_ABNORMAL);
700 /* Degenerate case of computed goto with no labels. */
701 if (!for_call && !bb->succ)
702 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
706 /*---------------------------------------------------------------------------
708 ---------------------------------------------------------------------------*/
710 /* Remove unreachable blocks and other miscellaneous clean up work. */
713 cleanup_tree_cfg (void)
715 bool something_changed = true;
718 timevar_push (TV_TREE_CLEANUP_CFG);
720 /* These three transformations can cascade, so we iterate on them until
722 while (something_changed)
724 something_changed = cleanup_control_flow ();
725 something_changed |= delete_unreachable_blocks ();
726 something_changed |= thread_jumps ();
727 retval |= something_changed;
730 /* Merging the blocks creates no new opportunities for the other
731 optimizations, so do it here. */
736 #ifdef ENABLE_CHECKING
739 timevar_pop (TV_TREE_CLEANUP_CFG);
744 /* Cleanup useless labels in basic blocks. This is something we wish
745 to do early because it allows us to group case labels before creating
746 the edges for the CFG, and it speeds up block statement iterators in
748 We only run this pass once, running it more than once is probably not
751 /* A map from basic block index to the leading label of that block. */
752 static tree *label_for_bb;
754 /* Callback for for_each_eh_region. Helper for cleanup_dead_labels. */
756 update_eh_label (struct eh_region *region)
758 tree old_label = get_eh_region_tree_label (region);
762 basic_block bb = label_to_block (old_label);
764 /* ??? After optimizing, there may be EH regions with labels
765 that have already been removed from the function body, so
766 there is no basic block for them. */
770 new_label = label_for_bb[bb->index];
771 set_eh_region_tree_label (region, new_label);
775 /* Given LABEL return the first label in the same basic block. */
777 main_block_label (tree label)
779 basic_block bb = label_to_block (label);
781 /* label_to_block possibly inserted undefined label into the chain. */
782 if (!label_for_bb[bb->index])
783 label_for_bb[bb->index] = label;
784 return label_for_bb[bb->index];
787 /* Cleanup redundant labels. This is a three-steo process:
788 1) Find the leading label for each block.
789 2) Redirect all references to labels to the leading labels.
790 3) Cleanup all useless labels. */
793 cleanup_dead_labels (void)
796 label_for_bb = xcalloc (last_basic_block, sizeof (tree));
798 /* Find a suitable label for each block. We use the first user-defined
799 label is there is one, or otherwise just the first label we see. */
802 block_stmt_iterator i;
804 for (i = bsi_start (bb); !bsi_end_p (i); bsi_next (&i))
806 tree label, stmt = bsi_stmt (i);
808 if (TREE_CODE (stmt) != LABEL_EXPR)
811 label = LABEL_EXPR_LABEL (stmt);
813 /* If we have not yet seen a label for the current block,
814 remember this one and see if there are more labels. */
815 if (! label_for_bb[bb->index])
817 label_for_bb[bb->index] = label;
821 /* If we did see a label for the current block already, but it
822 is an artificially created label, replace it if the current
823 label is a user defined label. */
824 if (! DECL_ARTIFICIAL (label)
825 && DECL_ARTIFICIAL (label_for_bb[bb->index]))
827 label_for_bb[bb->index] = label;
833 /* Now redirect all jumps/branches to the selected label.
834 First do so for each block ending in a control statement. */
837 tree stmt = last_stmt (bb);
841 switch (TREE_CODE (stmt))
845 tree true_branch, false_branch;
847 true_branch = COND_EXPR_THEN (stmt);
848 false_branch = COND_EXPR_ELSE (stmt);
850 GOTO_DESTINATION (true_branch)
851 = main_block_label (GOTO_DESTINATION (true_branch));
852 GOTO_DESTINATION (false_branch)
853 = main_block_label (GOTO_DESTINATION (false_branch));
861 tree vec = SWITCH_LABELS (stmt);
862 size_t n = TREE_VEC_LENGTH (vec);
864 /* Replace all destination labels. */
865 for (i = 0; i < n; ++i)
866 CASE_LABEL (TREE_VEC_ELT (vec, i))
867 = main_block_label (CASE_LABEL (TREE_VEC_ELT (vec, i)));
872 /* We have to handle GOTO_EXPRs until they're removed, and we don't
873 remove them until after we've created the CFG edges. */
875 if (! computed_goto_p (stmt))
877 GOTO_DESTINATION (stmt)
878 = main_block_label (GOTO_DESTINATION (stmt));
887 for_each_eh_region (update_eh_label);
889 /* Finally, purge dead labels. All user-defined labels and labels that
890 can be the target of non-local gotos are preserved. */
893 block_stmt_iterator i;
894 tree label_for_this_bb = label_for_bb[bb->index];
896 if (! label_for_this_bb)
899 for (i = bsi_start (bb); !bsi_end_p (i); )
901 tree label, stmt = bsi_stmt (i);
903 if (TREE_CODE (stmt) != LABEL_EXPR)
906 label = LABEL_EXPR_LABEL (stmt);
908 if (label == label_for_this_bb
909 || ! DECL_ARTIFICIAL (label)
910 || DECL_NONLOCAL (label))
920 /* Look for blocks ending in a multiway branch (a SWITCH_EXPR in GIMPLE),
921 and scan the sorted vector of cases. Combine the ones jumping to the
923 Eg. three separate entries 1: 2: 3: become one entry 1..3: */
926 group_case_labels (void)
932 tree stmt = last_stmt (bb);
933 if (stmt && TREE_CODE (stmt) == SWITCH_EXPR)
935 tree labels = SWITCH_LABELS (stmt);
936 int old_size = TREE_VEC_LENGTH (labels);
937 int i, j, new_size = old_size;
938 tree default_label = TREE_VEC_ELT (labels, old_size - 1);
940 /* Look for possible opportunities to merge cases.
941 Ignore the last element of the label vector because it
942 must be the default case. */
944 while (i < old_size - 2)
946 tree base_case, base_label, base_high, type;
947 base_case = TREE_VEC_ELT (labels, i);
949 gcc_assert (base_case);
950 base_label = CASE_LABEL (base_case);
952 /* Discard cases that have the same destination as the
954 if (base_label == default_label)
956 TREE_VEC_ELT (labels, i) = NULL_TREE;
961 type = TREE_TYPE (CASE_LOW (base_case));
962 base_high = CASE_HIGH (base_case) ?
963 CASE_HIGH (base_case) : CASE_LOW (base_case);
965 /* Try to merge case labels. Break out when we reach the end
966 of the label vector or when we cannot merge the next case
967 label with the current one. */
968 while (i < old_size - 2)
970 tree merge_case = TREE_VEC_ELT (labels, ++i);
971 tree merge_label = CASE_LABEL (merge_case);
972 tree t = int_const_binop (PLUS_EXPR, base_high,
973 integer_one_node, 1);
975 /* Merge the cases if they jump to the same place,
976 and their ranges are consecutive. */
977 if (merge_label == base_label
978 && tree_int_cst_equal (CASE_LOW (merge_case), t))
980 base_high = CASE_HIGH (merge_case) ?
981 CASE_HIGH (merge_case) : CASE_LOW (merge_case);
982 CASE_HIGH (base_case) = base_high;
983 TREE_VEC_ELT (labels, i) = NULL_TREE;
991 /* Compress the case labels in the label vector, and adjust the
992 length of the vector. */
993 for (i = 0, j = 0; i < new_size; i++)
995 while (! TREE_VEC_ELT (labels, j))
997 TREE_VEC_ELT (labels, i) = TREE_VEC_ELT (labels, j++);
999 TREE_VEC_LENGTH (labels) = new_size;
1004 /* Checks whether we can merge block B into block A. */
1007 tree_can_merge_blocks_p (basic_block a, basic_block b)
1010 block_stmt_iterator bsi;
1013 || a->succ->succ_next)
1016 if (a->succ->flags & EDGE_ABNORMAL)
1019 if (a->succ->dest != b)
1022 if (b == EXIT_BLOCK_PTR)
1025 if (b->pred->pred_next)
1028 /* If A ends by a statement causing exceptions or something similar, we
1029 cannot merge the blocks. */
1030 stmt = last_stmt (a);
1031 if (stmt && stmt_ends_bb_p (stmt))
1034 /* Do not allow a block with only a non-local label to be merged. */
1035 if (stmt && TREE_CODE (stmt) == LABEL_EXPR
1036 && DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)))
1039 /* There may be no phi nodes at the start of b. Most of these degenerate
1040 phi nodes should be cleaned up by kill_redundant_phi_nodes. */
1044 /* Do not remove user labels. */
1045 for (bsi = bsi_start (b); !bsi_end_p (bsi); bsi_next (&bsi))
1047 stmt = bsi_stmt (bsi);
1048 if (TREE_CODE (stmt) != LABEL_EXPR)
1050 if (!DECL_ARTIFICIAL (LABEL_EXPR_LABEL (stmt)))
1058 /* Merge block B into block A. */
1061 tree_merge_blocks (basic_block a, basic_block b)
1063 block_stmt_iterator bsi;
1064 tree_stmt_iterator last;
1067 fprintf (dump_file, "Merging blocks %d and %d\n", a->index, b->index);
1069 /* Ensure that B follows A. */
1070 move_block_after (b, a);
1072 gcc_assert (a->succ->flags & EDGE_FALLTHRU);
1073 gcc_assert (!last_stmt (a) || !stmt_ends_bb_p (last_stmt (a)));
1075 /* Remove labels from B and set bb_for_stmt to A for other statements. */
1076 for (bsi = bsi_start (b); !bsi_end_p (bsi);)
1078 if (TREE_CODE (bsi_stmt (bsi)) == LABEL_EXPR)
1082 set_bb_for_stmt (bsi_stmt (bsi), a);
1087 /* Merge the chains. */
1088 last = tsi_last (a->stmt_list);
1089 tsi_link_after (&last, b->stmt_list, TSI_NEW_STMT);
1090 b->stmt_list = NULL;
1094 /* Walk the function tree removing unnecessary statements.
1096 * Empty statement nodes are removed
1098 * Unnecessary TRY_FINALLY and TRY_CATCH blocks are removed
1100 * Unnecessary COND_EXPRs are removed
1102 * Some unnecessary BIND_EXPRs are removed
1104 Clearly more work could be done. The trick is doing the analysis
1105 and removal fast enough to be a net improvement in compile times.
1107 Note that when we remove a control structure such as a COND_EXPR
1108 BIND_EXPR, or TRY block, we will need to repeat this optimization pass
1109 to ensure we eliminate all the useless code. */
1120 static void remove_useless_stmts_1 (tree *, struct rus_data *);
1123 remove_useless_stmts_warn_notreached (tree stmt)
1125 if (EXPR_HAS_LOCATION (stmt))
1127 location_t loc = EXPR_LOCATION (stmt);
1128 warning ("%Hwill never be executed", &loc);
1132 switch (TREE_CODE (stmt))
1134 case STATEMENT_LIST:
1136 tree_stmt_iterator i;
1137 for (i = tsi_start (stmt); !tsi_end_p (i); tsi_next (&i))
1138 if (remove_useless_stmts_warn_notreached (tsi_stmt (i)))
1144 if (remove_useless_stmts_warn_notreached (COND_EXPR_COND (stmt)))
1146 if (remove_useless_stmts_warn_notreached (COND_EXPR_THEN (stmt)))
1148 if (remove_useless_stmts_warn_notreached (COND_EXPR_ELSE (stmt)))
1152 case TRY_FINALLY_EXPR:
1153 case TRY_CATCH_EXPR:
1154 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt, 0)))
1156 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt, 1)))
1161 return remove_useless_stmts_warn_notreached (CATCH_BODY (stmt));
1162 case EH_FILTER_EXPR:
1163 return remove_useless_stmts_warn_notreached (EH_FILTER_FAILURE (stmt));
1165 return remove_useless_stmts_warn_notreached (BIND_EXPR_BLOCK (stmt));
1168 /* Not a live container. */
1176 remove_useless_stmts_cond (tree *stmt_p, struct rus_data *data)
1178 tree then_clause, else_clause, cond;
1179 bool save_has_label, then_has_label, else_has_label;
1181 save_has_label = data->has_label;
1182 data->has_label = false;
1183 data->last_goto = NULL;
1185 remove_useless_stmts_1 (&COND_EXPR_THEN (*stmt_p), data);
1187 then_has_label = data->has_label;
1188 data->has_label = false;
1189 data->last_goto = NULL;
1191 remove_useless_stmts_1 (&COND_EXPR_ELSE (*stmt_p), data);
1193 else_has_label = data->has_label;
1194 data->has_label = save_has_label | then_has_label | else_has_label;
1197 then_clause = COND_EXPR_THEN (*stmt_p);
1198 else_clause = COND_EXPR_ELSE (*stmt_p);
1199 cond = COND_EXPR_COND (*stmt_p);
1201 /* If neither arm does anything at all, we can remove the whole IF. */
1202 if (!TREE_SIDE_EFFECTS (then_clause) && !TREE_SIDE_EFFECTS (else_clause))
1204 *stmt_p = build_empty_stmt ();
1205 data->repeat = true;
1208 /* If there are no reachable statements in an arm, then we can
1209 zap the entire conditional. */
1210 else if (integer_nonzerop (cond) && !else_has_label)
1212 if (warn_notreached)
1213 remove_useless_stmts_warn_notreached (else_clause);
1214 *stmt_p = then_clause;
1215 data->repeat = true;
1217 else if (integer_zerop (cond) && !then_has_label)
1219 if (warn_notreached)
1220 remove_useless_stmts_warn_notreached (then_clause);
1221 *stmt_p = else_clause;
1222 data->repeat = true;
1225 /* Check a couple of simple things on then/else with single stmts. */
1228 tree then_stmt = expr_only (then_clause);
1229 tree else_stmt = expr_only (else_clause);
1231 /* Notice branches to a common destination. */
1232 if (then_stmt && else_stmt
1233 && TREE_CODE (then_stmt) == GOTO_EXPR
1234 && TREE_CODE (else_stmt) == GOTO_EXPR
1235 && (GOTO_DESTINATION (then_stmt) == GOTO_DESTINATION (else_stmt)))
1237 *stmt_p = then_stmt;
1238 data->repeat = true;
1241 /* If the THEN/ELSE clause merely assigns a value to a variable or
1242 parameter which is already known to contain that value, then
1243 remove the useless THEN/ELSE clause. */
1244 else if (TREE_CODE (cond) == VAR_DECL || TREE_CODE (cond) == PARM_DECL)
1247 && TREE_CODE (else_stmt) == MODIFY_EXPR
1248 && TREE_OPERAND (else_stmt, 0) == cond
1249 && integer_zerop (TREE_OPERAND (else_stmt, 1)))
1250 COND_EXPR_ELSE (*stmt_p) = alloc_stmt_list ();
1252 else if ((TREE_CODE (cond) == EQ_EXPR || TREE_CODE (cond) == NE_EXPR)
1253 && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL
1254 || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL)
1255 && TREE_CONSTANT (TREE_OPERAND (cond, 1)))
1257 tree stmt = (TREE_CODE (cond) == EQ_EXPR
1258 ? then_stmt : else_stmt);
1259 tree *location = (TREE_CODE (cond) == EQ_EXPR
1260 ? &COND_EXPR_THEN (*stmt_p)
1261 : &COND_EXPR_ELSE (*stmt_p));
1264 && TREE_CODE (stmt) == MODIFY_EXPR
1265 && TREE_OPERAND (stmt, 0) == TREE_OPERAND (cond, 0)
1266 && TREE_OPERAND (stmt, 1) == TREE_OPERAND (cond, 1))
1267 *location = alloc_stmt_list ();
1271 /* Protect GOTOs in the arm of COND_EXPRs from being removed. They
1272 would be re-introduced during lowering. */
1273 data->last_goto = NULL;
1278 remove_useless_stmts_tf (tree *stmt_p, struct rus_data *data)
1280 bool save_may_branch, save_may_throw;
1281 bool this_may_branch, this_may_throw;
1283 /* Collect may_branch and may_throw information for the body only. */
1284 save_may_branch = data->may_branch;
1285 save_may_throw = data->may_throw;
1286 data->may_branch = false;
1287 data->may_throw = false;
1288 data->last_goto = NULL;
1290 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 0), data);
1292 this_may_branch = data->may_branch;
1293 this_may_throw = data->may_throw;
1294 data->may_branch |= save_may_branch;
1295 data->may_throw |= save_may_throw;
1296 data->last_goto = NULL;
1298 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 1), data);
1300 /* If the body is empty, then we can emit the FINALLY block without
1301 the enclosing TRY_FINALLY_EXPR. */
1302 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 0)))
1304 *stmt_p = TREE_OPERAND (*stmt_p, 1);
1305 data->repeat = true;
1308 /* If the handler is empty, then we can emit the TRY block without
1309 the enclosing TRY_FINALLY_EXPR. */
1310 else if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 1)))
1312 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1313 data->repeat = true;
1316 /* If the body neither throws, nor branches, then we can safely
1317 string the TRY and FINALLY blocks together. */
1318 else if (!this_may_branch && !this_may_throw)
1320 tree stmt = *stmt_p;
1321 *stmt_p = TREE_OPERAND (stmt, 0);
1322 append_to_statement_list (TREE_OPERAND (stmt, 1), stmt_p);
1323 data->repeat = true;
1329 remove_useless_stmts_tc (tree *stmt_p, struct rus_data *data)
1331 bool save_may_throw, this_may_throw;
1332 tree_stmt_iterator i;
1335 /* Collect may_throw information for the body only. */
1336 save_may_throw = data->may_throw;
1337 data->may_throw = false;
1338 data->last_goto = NULL;
1340 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 0), data);
1342 this_may_throw = data->may_throw;
1343 data->may_throw = save_may_throw;
1345 /* If the body cannot throw, then we can drop the entire TRY_CATCH_EXPR. */
1346 if (!this_may_throw)
1348 if (warn_notreached)
1349 remove_useless_stmts_warn_notreached (TREE_OPERAND (*stmt_p, 1));
1350 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1351 data->repeat = true;
1355 /* Process the catch clause specially. We may be able to tell that
1356 no exceptions propagate past this point. */
1358 this_may_throw = true;
1359 i = tsi_start (TREE_OPERAND (*stmt_p, 1));
1360 stmt = tsi_stmt (i);
1361 data->last_goto = NULL;
1363 switch (TREE_CODE (stmt))
1366 for (; !tsi_end_p (i); tsi_next (&i))
1368 stmt = tsi_stmt (i);
1369 /* If we catch all exceptions, then the body does not
1370 propagate exceptions past this point. */
1371 if (CATCH_TYPES (stmt) == NULL)
1372 this_may_throw = false;
1373 data->last_goto = NULL;
1374 remove_useless_stmts_1 (&CATCH_BODY (stmt), data);
1378 case EH_FILTER_EXPR:
1379 if (EH_FILTER_MUST_NOT_THROW (stmt))
1380 this_may_throw = false;
1381 else if (EH_FILTER_TYPES (stmt) == NULL)
1382 this_may_throw = false;
1383 remove_useless_stmts_1 (&EH_FILTER_FAILURE (stmt), data);
1387 /* Otherwise this is a cleanup. */
1388 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 1), data);
1390 /* If the cleanup is empty, then we can emit the TRY block without
1391 the enclosing TRY_CATCH_EXPR. */
1392 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 1)))
1394 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1395 data->repeat = true;
1399 data->may_throw |= this_may_throw;
1404 remove_useless_stmts_bind (tree *stmt_p, struct rus_data *data)
1408 /* First remove anything underneath the BIND_EXPR. */
1409 remove_useless_stmts_1 (&BIND_EXPR_BODY (*stmt_p), data);
1411 /* If the BIND_EXPR has no variables, then we can pull everything
1412 up one level and remove the BIND_EXPR, unless this is the toplevel
1413 BIND_EXPR for the current function or an inlined function.
1415 When this situation occurs we will want to apply this
1416 optimization again. */
1417 block = BIND_EXPR_BLOCK (*stmt_p);
1418 if (BIND_EXPR_VARS (*stmt_p) == NULL_TREE
1419 && *stmt_p != DECL_SAVED_TREE (current_function_decl)
1421 || ! BLOCK_ABSTRACT_ORIGIN (block)
1422 || (TREE_CODE (BLOCK_ABSTRACT_ORIGIN (block))
1425 *stmt_p = BIND_EXPR_BODY (*stmt_p);
1426 data->repeat = true;
1432 remove_useless_stmts_goto (tree *stmt_p, struct rus_data *data)
1434 tree dest = GOTO_DESTINATION (*stmt_p);
1436 data->may_branch = true;
1437 data->last_goto = NULL;
1439 /* Record the last goto expr, so that we can delete it if unnecessary. */
1440 if (TREE_CODE (dest) == LABEL_DECL)
1441 data->last_goto = stmt_p;
1446 remove_useless_stmts_label (tree *stmt_p, struct rus_data *data)
1448 tree label = LABEL_EXPR_LABEL (*stmt_p);
1450 data->has_label = true;
1452 /* We do want to jump across non-local label receiver code. */
1453 if (DECL_NONLOCAL (label))
1454 data->last_goto = NULL;
1456 else if (data->last_goto && GOTO_DESTINATION (*data->last_goto) == label)
1458 *data->last_goto = build_empty_stmt ();
1459 data->repeat = true;
1462 /* ??? Add something here to delete unused labels. */
1466 /* If the function is "const" or "pure", then clear TREE_SIDE_EFFECTS on its
1467 decl. This allows us to eliminate redundant or useless
1468 calls to "const" functions.
1470 Gimplifier already does the same operation, but we may notice functions
1471 being const and pure once their calls has been gimplified, so we need
1472 to update the flag. */
1475 update_call_expr_flags (tree call)
1477 tree decl = get_callee_fndecl (call);
1480 if (call_expr_flags (call) & (ECF_CONST | ECF_PURE))
1481 TREE_SIDE_EFFECTS (call) = 0;
1482 if (TREE_NOTHROW (decl))
1483 TREE_NOTHROW (call) = 1;
1487 /* T is CALL_EXPR. Set current_function_calls_* flags. */
1490 notice_special_calls (tree t)
1492 int flags = call_expr_flags (t);
1494 if (flags & ECF_MAY_BE_ALLOCA)
1495 current_function_calls_alloca = true;
1496 if (flags & ECF_RETURNS_TWICE)
1497 current_function_calls_setjmp = true;
1501 /* Clear flags set by notice_special_calls. Used by dead code removal
1502 to update the flags. */
1505 clear_special_calls (void)
1507 current_function_calls_alloca = false;
1508 current_function_calls_setjmp = false;
1513 remove_useless_stmts_1 (tree *tp, struct rus_data *data)
1517 switch (TREE_CODE (t))
1520 remove_useless_stmts_cond (tp, data);
1523 case TRY_FINALLY_EXPR:
1524 remove_useless_stmts_tf (tp, data);
1527 case TRY_CATCH_EXPR:
1528 remove_useless_stmts_tc (tp, data);
1532 remove_useless_stmts_bind (tp, data);
1536 remove_useless_stmts_goto (tp, data);
1540 remove_useless_stmts_label (tp, data);
1545 data->last_goto = NULL;
1546 data->may_branch = true;
1551 data->last_goto = NULL;
1552 notice_special_calls (t);
1553 update_call_expr_flags (t);
1554 if (tree_could_throw_p (t))
1555 data->may_throw = true;
1559 data->last_goto = NULL;
1561 op = get_call_expr_in (t);
1564 update_call_expr_flags (op);
1565 notice_special_calls (op);
1567 if (tree_could_throw_p (t))
1568 data->may_throw = true;
1571 case STATEMENT_LIST:
1573 tree_stmt_iterator i = tsi_start (t);
1574 while (!tsi_end_p (i))
1577 if (IS_EMPTY_STMT (t))
1583 remove_useless_stmts_1 (tsi_stmt_ptr (i), data);
1586 if (TREE_CODE (t) == STATEMENT_LIST)
1588 tsi_link_before (&i, t, TSI_SAME_STMT);
1598 data->last_goto = NULL;
1602 data->last_goto = NULL;
1608 remove_useless_stmts (void)
1610 struct rus_data data;
1612 clear_special_calls ();
1616 memset (&data, 0, sizeof (data));
1617 remove_useless_stmts_1 (&DECL_SAVED_TREE (current_function_decl), &data);
1619 while (data.repeat);
1623 struct tree_opt_pass pass_remove_useless_stmts =
1625 "useless", /* name */
1627 remove_useless_stmts, /* execute */
1630 0, /* static_pass_number */
1632 PROP_gimple_any, /* properties_required */
1633 0, /* properties_provided */
1634 0, /* properties_destroyed */
1635 0, /* todo_flags_start */
1636 TODO_dump_func, /* todo_flags_finish */
1641 /* Remove obviously useless statements in basic block BB. */
1644 cfg_remove_useless_stmts_bb (basic_block bb)
1646 block_stmt_iterator bsi;
1647 tree stmt = NULL_TREE;
1648 tree cond, var = NULL_TREE, val = NULL_TREE;
1649 struct var_ann_d *ann;
1651 /* Check whether we come here from a condition, and if so, get the
1654 || bb->pred->pred_next
1655 || !(bb->pred->flags & (EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
1658 cond = COND_EXPR_COND (last_stmt (bb->pred->src));
1660 if (TREE_CODE (cond) == VAR_DECL || TREE_CODE (cond) == PARM_DECL)
1663 val = (bb->pred->flags & EDGE_FALSE_VALUE
1664 ? boolean_false_node : boolean_true_node);
1666 else if (TREE_CODE (cond) == TRUTH_NOT_EXPR
1667 && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL
1668 || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL))
1670 var = TREE_OPERAND (cond, 0);
1671 val = (bb->pred->flags & EDGE_FALSE_VALUE
1672 ? boolean_true_node : boolean_false_node);
1676 if (bb->pred->flags & EDGE_FALSE_VALUE)
1677 cond = invert_truthvalue (cond);
1678 if (TREE_CODE (cond) == EQ_EXPR
1679 && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL
1680 || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL)
1681 && (TREE_CODE (TREE_OPERAND (cond, 1)) == VAR_DECL
1682 || TREE_CODE (TREE_OPERAND (cond, 1)) == PARM_DECL
1683 || TREE_CONSTANT (TREE_OPERAND (cond, 1))))
1685 var = TREE_OPERAND (cond, 0);
1686 val = TREE_OPERAND (cond, 1);
1692 /* Only work for normal local variables. */
1693 ann = var_ann (var);
1696 || TREE_ADDRESSABLE (var))
1699 if (! TREE_CONSTANT (val))
1701 ann = var_ann (val);
1704 || TREE_ADDRESSABLE (val))
1708 /* Ignore floating point variables, since comparison behaves weird for
1710 if (FLOAT_TYPE_P (TREE_TYPE (var)))
1713 for (bsi = bsi_start (bb); !bsi_end_p (bsi);)
1715 stmt = bsi_stmt (bsi);
1717 /* If the THEN/ELSE clause merely assigns a value to a variable/parameter
1718 which is already known to contain that value, then remove the useless
1719 THEN/ELSE clause. */
1720 if (TREE_CODE (stmt) == MODIFY_EXPR
1721 && TREE_OPERAND (stmt, 0) == var
1722 && operand_equal_p (val, TREE_OPERAND (stmt, 1), 0))
1728 /* Invalidate the var if we encounter something that could modify it.
1729 Likewise for the value it was previously set to. Note that we only
1730 consider values that are either a VAR_DECL or PARM_DECL so we
1731 can test for conflict very simply. */
1732 if (TREE_CODE (stmt) == ASM_EXPR
1733 || (TREE_CODE (stmt) == MODIFY_EXPR
1734 && (TREE_OPERAND (stmt, 0) == var
1735 || TREE_OPERAND (stmt, 0) == val)))
1743 /* A CFG-aware version of remove_useless_stmts. */
1746 cfg_remove_useless_stmts (void)
1750 #ifdef ENABLE_CHECKING
1751 verify_flow_info ();
1756 cfg_remove_useless_stmts_bb (bb);
1761 /* Remove PHI nodes associated with basic block BB and all edges out of BB. */
1764 remove_phi_nodes_and_edges_for_unreachable_block (basic_block bb)
1768 /* Since this block is no longer reachable, we can just delete all
1769 of its PHI nodes. */
1770 phi = phi_nodes (bb);
1773 tree next = PHI_CHAIN (phi);
1774 remove_phi_node (phi, NULL_TREE, bb);
1778 /* Remove edges to BB's successors. */
1779 while (bb->succ != NULL)
1780 ssa_remove_edge (bb->succ);
1784 /* Remove statements of basic block BB. */
1787 remove_bb (basic_block bb)
1789 block_stmt_iterator i;
1790 source_locus loc = 0;
1794 fprintf (dump_file, "Removing basic block %d\n", bb->index);
1795 if (dump_flags & TDF_DETAILS)
1797 dump_bb (bb, dump_file, 0);
1798 fprintf (dump_file, "\n");
1802 /* Remove all the instructions in the block. */
1803 for (i = bsi_start (bb); !bsi_end_p (i); bsi_remove (&i))
1805 tree stmt = bsi_stmt (i);
1806 release_defs (stmt);
1808 set_bb_for_stmt (stmt, NULL);
1810 /* Don't warn for removed gotos. Gotos are often removed due to
1811 jump threading, thus resulting in bogus warnings. Not great,
1812 since this way we lose warnings for gotos in the original
1813 program that are indeed unreachable. */
1814 if (TREE_CODE (stmt) != GOTO_EXPR && EXPR_HAS_LOCATION (stmt) && !loc)
1815 #ifdef USE_MAPPED_LOCATION
1816 loc = EXPR_LOCATION (stmt);
1818 loc = EXPR_LOCUS (stmt);
1822 /* If requested, give a warning that the first statement in the
1823 block is unreachable. We walk statements backwards in the
1824 loop above, so the last statement we process is the first statement
1826 if (warn_notreached && loc)
1827 #ifdef USE_MAPPED_LOCATION
1828 warning ("%Hwill never be executed", &loc);
1830 warning ("%Hwill never be executed", loc);
1833 remove_phi_nodes_and_edges_for_unreachable_block (bb);
1837 /* Examine BB to determine if it is a forwarding block (a block which only
1838 transfers control to a new destination). If BB is a forwarding block,
1839 then return the edge leading to the ultimate destination. */
1842 tree_block_forwards_to (basic_block bb)
1844 block_stmt_iterator bsi;
1845 bb_ann_t ann = bb_ann (bb);
1848 /* If this block is not forwardable, then avoid useless work. */
1849 if (! ann->forwardable)
1852 /* Set this block to not be forwardable. This prevents infinite loops since
1853 any block currently under examination is considered non-forwardable. */
1854 ann->forwardable = 0;
1856 /* No forwarding is possible if this block is a special block (ENTRY/EXIT),
1857 this block has more than one successor, this block's single successor is
1858 reached via an abnormal edge, this block has phi nodes, or this block's
1859 single successor has phi nodes. */
1860 if (bb == EXIT_BLOCK_PTR
1861 || bb == ENTRY_BLOCK_PTR
1863 || bb->succ->succ_next
1864 || bb->succ->dest == EXIT_BLOCK_PTR
1865 || (bb->succ->flags & EDGE_ABNORMAL) != 0
1867 || phi_nodes (bb->succ->dest))
1870 /* Walk past any labels at the start of this block. */
1871 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
1873 stmt = bsi_stmt (bsi);
1874 if (TREE_CODE (stmt) != LABEL_EXPR)
1878 /* If we reached the end of this block we may be able to optimize this
1880 if (bsi_end_p (bsi))
1884 /* Recursive call to pick up chains of forwarding blocks. */
1885 dest = tree_block_forwards_to (bb->succ->dest);
1887 /* If none found, we forward to bb->succ at minimum. */
1891 ann->forwardable = 1;
1895 /* No forwarding possible. */
1900 /* Try to remove superfluous control structures. */
1903 cleanup_control_flow (void)
1906 block_stmt_iterator bsi;
1907 bool retval = false;
1912 bsi = bsi_last (bb);
1914 if (bsi_end_p (bsi))
1917 stmt = bsi_stmt (bsi);
1918 if (TREE_CODE (stmt) == COND_EXPR
1919 || TREE_CODE (stmt) == SWITCH_EXPR)
1920 retval |= cleanup_control_expr_graph (bb, bsi);
1926 /* Disconnect an unreachable block in the control expression starting
1930 cleanup_control_expr_graph (basic_block bb, block_stmt_iterator bsi)
1933 bool retval = false;
1934 tree expr = bsi_stmt (bsi), val;
1936 if (bb->succ->succ_next)
1940 switch (TREE_CODE (expr))
1943 val = COND_EXPR_COND (expr);
1947 val = SWITCH_COND (expr);
1948 if (TREE_CODE (val) != INTEGER_CST)
1956 taken_edge = find_taken_edge (bb, val);
1960 /* Remove all the edges except the one that is always executed. */
1961 for (e = bb->succ; e; e = next)
1963 next = e->succ_next;
1964 if (e != taken_edge)
1966 taken_edge->probability += e->probability;
1967 taken_edge->count += e->count;
1968 ssa_remove_edge (e);
1972 if (taken_edge->probability > REG_BR_PROB_BASE)
1973 taken_edge->probability = REG_BR_PROB_BASE;
1976 taken_edge = bb->succ;
1979 taken_edge->flags = EDGE_FALLTHRU;
1981 /* We removed some paths from the cfg. */
1982 if (dom_computed[CDI_DOMINATORS] >= DOM_CONS_OK)
1983 dom_computed[CDI_DOMINATORS] = DOM_CONS_OK;
1989 /* Given a control block BB and a predicate VAL, return the edge that
1990 will be taken out of the block. If VAL does not match a unique
1991 edge, NULL is returned. */
1994 find_taken_edge (basic_block bb, tree val)
1998 stmt = last_stmt (bb);
2001 gcc_assert (is_ctrl_stmt (stmt));
2003 /* If VAL is a predicate of the form N RELOP N, where N is an
2004 SSA_NAME, we can usually determine its truth value. */
2005 if (val && COMPARISON_CLASS_P (val))
2008 /* If VAL is not a constant, we can't determine which edge might
2010 if (val == NULL || !really_constant_p (val))
2013 if (TREE_CODE (stmt) == COND_EXPR)
2014 return find_taken_edge_cond_expr (bb, val);
2016 if (TREE_CODE (stmt) == SWITCH_EXPR)
2017 return find_taken_edge_switch_expr (bb, val);
2023 /* Given a constant value VAL and the entry block BB to a COND_EXPR
2024 statement, determine which of the two edges will be taken out of the
2025 block. Return NULL if either edge may be taken. */
2028 find_taken_edge_cond_expr (basic_block bb, tree val)
2030 edge true_edge, false_edge;
2032 extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
2034 /* If both edges of the branch lead to the same basic block, it doesn't
2035 matter which edge is taken. */
2036 if (true_edge->dest == false_edge->dest)
2039 /* Otherwise, try to determine which branch of the if() will be taken.
2040 If VAL is a constant but it can't be reduced to a 0 or a 1, then
2041 we don't really know which edge will be taken at runtime. This
2042 may happen when comparing addresses (e.g., if (&var1 == 4)). */
2043 if (integer_nonzerop (val))
2045 else if (integer_zerop (val))
2052 /* Given a constant value VAL and the entry block BB to a SWITCH_EXPR
2053 statement, determine which edge will be taken out of the block. Return
2054 NULL if any edge may be taken. */
2057 find_taken_edge_switch_expr (basic_block bb, tree val)
2059 tree switch_expr, taken_case;
2060 basic_block dest_bb;
2063 if (TREE_CODE (val) != INTEGER_CST)
2066 switch_expr = last_stmt (bb);
2067 taken_case = find_case_label_for_value (switch_expr, val);
2068 dest_bb = label_to_block (CASE_LABEL (taken_case));
2070 e = find_edge (bb, dest_bb);
2076 /* Return the CASE_LABEL_EXPR that SWITCH_EXPR will take for VAL.
2077 We can make optimal use here of the fact that the case labels are
2078 sorted: We can do a binary search for a case matching VAL. */
2081 find_case_label_for_value (tree switch_expr, tree val)
2083 tree vec = SWITCH_LABELS (switch_expr);
2084 size_t low, high, n = TREE_VEC_LENGTH (vec);
2085 tree default_case = TREE_VEC_ELT (vec, n - 1);
2087 for (low = -1, high = n - 1; high - low > 1; )
2089 size_t i = (high + low) / 2;
2090 tree t = TREE_VEC_ELT (vec, i);
2093 /* Cache the result of comparing CASE_LOW and val. */
2094 cmp = tree_int_cst_compare (CASE_LOW (t), val);
2101 if (CASE_HIGH (t) == NULL)
2103 /* A singe-valued case label. */
2109 /* A case range. We can only handle integer ranges. */
2110 if (cmp <= 0 && tree_int_cst_compare (CASE_HIGH (t), val) >= 0)
2115 return default_case;
2119 /* If all the PHI nodes in DEST have alternatives for E1 and E2 and
2120 those alternatives are equal in each of the PHI nodes, then return
2121 true, else return false. */
2124 phi_alternatives_equal (basic_block dest, edge e1, edge e2)
2126 tree phi, val1, val2;
2129 for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi))
2131 n1 = phi_arg_from_edge (phi, e1);
2132 n2 = phi_arg_from_edge (phi, e2);
2134 gcc_assert (n1 >= 0);
2135 gcc_assert (n2 >= 0);
2137 val1 = PHI_ARG_DEF (phi, n1);
2138 val2 = PHI_ARG_DEF (phi, n2);
2140 if (!operand_equal_p (val1, val2, 0))
2148 /*---------------------------------------------------------------------------
2150 ---------------------------------------------------------------------------*/
2152 /* Dump tree-specific information of block BB to file OUTF. */
2155 tree_dump_bb (basic_block bb, FILE *outf, int indent)
2157 dump_generic_bb (outf, bb, indent, TDF_VOPS);
2161 /* Dump a basic block on stderr. */
2164 debug_tree_bb (basic_block bb)
2166 dump_bb (bb, stderr, 0);
2170 /* Dump basic block with index N on stderr. */
2173 debug_tree_bb_n (int n)
2175 debug_tree_bb (BASIC_BLOCK (n));
2176 return BASIC_BLOCK (n);
2180 /* Dump the CFG on stderr.
2182 FLAGS are the same used by the tree dumping functions
2183 (see TDF_* in tree.h). */
2186 debug_tree_cfg (int flags)
2188 dump_tree_cfg (stderr, flags);
2192 /* Dump the program showing basic block boundaries on the given FILE.
2194 FLAGS are the same used by the tree dumping functions (see TDF_* in
2198 dump_tree_cfg (FILE *file, int flags)
2200 if (flags & TDF_DETAILS)
2202 const char *funcname
2203 = lang_hooks.decl_printable_name (current_function_decl, 2);
2206 fprintf (file, ";; Function %s\n\n", funcname);
2207 fprintf (file, ";; \n%d basic blocks, %d edges, last basic block %d.\n\n",
2208 n_basic_blocks, n_edges, last_basic_block);
2210 brief_dump_cfg (file);
2211 fprintf (file, "\n");
2214 if (flags & TDF_STATS)
2215 dump_cfg_stats (file);
2217 dump_function_to_file (current_function_decl, file, flags | TDF_BLOCKS);
2221 /* Dump CFG statistics on FILE. */
2224 dump_cfg_stats (FILE *file)
2226 static long max_num_merged_labels = 0;
2227 unsigned long size, total = 0;
2230 const char * const fmt_str = "%-30s%-13s%12s\n";
2231 const char * const fmt_str_1 = "%-30s%13d%11lu%c\n";
2232 const char * const fmt_str_3 = "%-43s%11lu%c\n";
2233 const char *funcname
2234 = lang_hooks.decl_printable_name (current_function_decl, 2);
2237 fprintf (file, "\nCFG Statistics for %s\n\n", funcname);
2239 fprintf (file, "---------------------------------------------------------\n");
2240 fprintf (file, fmt_str, "", " Number of ", "Memory");
2241 fprintf (file, fmt_str, "", " instances ", "used ");
2242 fprintf (file, "---------------------------------------------------------\n");
2244 size = n_basic_blocks * sizeof (struct basic_block_def);
2246 fprintf (file, fmt_str_1, "Basic blocks", n_basic_blocks,
2247 SCALE (size), LABEL (size));
2253 for (e = bb->succ; e; e = e->succ_next)
2256 size = n_edges * sizeof (struct edge_def);
2258 fprintf (file, fmt_str_1, "Edges", n_edges, SCALE (size), LABEL (size));
2260 size = n_basic_blocks * sizeof (struct bb_ann_d);
2262 fprintf (file, fmt_str_1, "Basic block annotations", n_basic_blocks,
2263 SCALE (size), LABEL (size));
2265 fprintf (file, "---------------------------------------------------------\n");
2266 fprintf (file, fmt_str_3, "Total memory used by CFG data", SCALE (total),
2268 fprintf (file, "---------------------------------------------------------\n");
2269 fprintf (file, "\n");
2271 if (cfg_stats.num_merged_labels > max_num_merged_labels)
2272 max_num_merged_labels = cfg_stats.num_merged_labels;
2274 fprintf (file, "Coalesced label blocks: %ld (Max so far: %ld)\n",
2275 cfg_stats.num_merged_labels, max_num_merged_labels);
2277 fprintf (file, "\n");
2281 /* Dump CFG statistics on stderr. Keep extern so that it's always
2282 linked in the final executable. */
2285 debug_cfg_stats (void)
2287 dump_cfg_stats (stderr);
2291 /* Dump the flowgraph to a .vcg FILE. */
2294 tree_cfg2vcg (FILE *file)
2298 const char *funcname
2299 = lang_hooks.decl_printable_name (current_function_decl, 2);
2301 /* Write the file header. */
2302 fprintf (file, "graph: { title: \"%s\"\n", funcname);
2303 fprintf (file, "node: { title: \"ENTRY\" label: \"ENTRY\" }\n");
2304 fprintf (file, "node: { title: \"EXIT\" label: \"EXIT\" }\n");
2306 /* Write blocks and edges. */
2307 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
2309 fprintf (file, "edge: { sourcename: \"ENTRY\" targetname: \"%d\"",
2312 if (e->flags & EDGE_FAKE)
2313 fprintf (file, " linestyle: dotted priority: 10");
2315 fprintf (file, " linestyle: solid priority: 100");
2317 fprintf (file, " }\n");
2323 enum tree_code head_code, end_code;
2324 const char *head_name, *end_name;
2327 tree first = first_stmt (bb);
2328 tree last = last_stmt (bb);
2332 head_code = TREE_CODE (first);
2333 head_name = tree_code_name[head_code];
2334 head_line = get_lineno (first);
2337 head_name = "no-statement";
2341 end_code = TREE_CODE (last);
2342 end_name = tree_code_name[end_code];
2343 end_line = get_lineno (last);
2346 end_name = "no-statement";
2348 fprintf (file, "node: { title: \"%d\" label: \"#%d\\n%s (%d)\\n%s (%d)\"}\n",
2349 bb->index, bb->index, head_name, head_line, end_name,
2352 for (e = bb->succ; e; e = e->succ_next)
2354 if (e->dest == EXIT_BLOCK_PTR)
2355 fprintf (file, "edge: { sourcename: \"%d\" targetname: \"EXIT\"", bb->index);
2357 fprintf (file, "edge: { sourcename: \"%d\" targetname: \"%d\"", bb->index, e->dest->index);
2359 if (e->flags & EDGE_FAKE)
2360 fprintf (file, " priority: 10 linestyle: dotted");
2362 fprintf (file, " priority: 100 linestyle: solid");
2364 fprintf (file, " }\n");
2367 if (bb->next_bb != EXIT_BLOCK_PTR)
2371 fputs ("}\n\n", file);
2376 /*---------------------------------------------------------------------------
2377 Miscellaneous helpers
2378 ---------------------------------------------------------------------------*/
2380 /* Return true if T represents a stmt that always transfers control. */
2383 is_ctrl_stmt (tree t)
2385 return (TREE_CODE (t) == COND_EXPR
2386 || TREE_CODE (t) == SWITCH_EXPR
2387 || TREE_CODE (t) == GOTO_EXPR
2388 || TREE_CODE (t) == RETURN_EXPR
2389 || TREE_CODE (t) == RESX_EXPR);
2393 /* Return true if T is a statement that may alter the flow of control
2394 (e.g., a call to a non-returning function). */
2397 is_ctrl_altering_stmt (tree t)
2402 call = get_call_expr_in (t);
2405 /* A non-pure/const CALL_EXPR alters flow control if the current
2406 function has nonlocal labels. */
2407 if (TREE_SIDE_EFFECTS (call) && current_function_has_nonlocal_label)
2410 /* A CALL_EXPR also alters control flow if it does not return. */
2411 if (call_expr_flags (call) & (ECF_NORETURN | ECF_LONGJMP))
2415 /* If a statement can throw, it alters control flow. */
2416 return tree_can_throw_internal (t);
2420 /* Return true if T is a computed goto. */
2423 computed_goto_p (tree t)
2425 return (TREE_CODE (t) == GOTO_EXPR
2426 && TREE_CODE (GOTO_DESTINATION (t)) != LABEL_DECL);
2430 /* Checks whether EXPR is a simple local goto. */
2433 simple_goto_p (tree expr)
2435 return (TREE_CODE (expr) == GOTO_EXPR
2436 && TREE_CODE (GOTO_DESTINATION (expr)) == LABEL_DECL);
2440 /* Return true if T should start a new basic block. PREV_T is the
2441 statement preceding T. It is used when T is a label or a case label.
2442 Labels should only start a new basic block if their previous statement
2443 wasn't a label. Otherwise, sequence of labels would generate
2444 unnecessary basic blocks that only contain a single label. */
2447 stmt_starts_bb_p (tree t, tree prev_t)
2449 enum tree_code code;
2454 /* LABEL_EXPRs start a new basic block only if the preceding
2455 statement wasn't a label of the same type. This prevents the
2456 creation of consecutive blocks that have nothing but a single
2458 code = TREE_CODE (t);
2459 if (code == LABEL_EXPR)
2461 /* Nonlocal and computed GOTO targets always start a new block. */
2462 if (code == LABEL_EXPR
2463 && (DECL_NONLOCAL (LABEL_EXPR_LABEL (t))
2464 || FORCED_LABEL (LABEL_EXPR_LABEL (t))))
2467 if (prev_t && TREE_CODE (prev_t) == code)
2469 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (prev_t)))
2472 cfg_stats.num_merged_labels++;
2483 /* Return true if T should end a basic block. */
2486 stmt_ends_bb_p (tree t)
2488 return is_ctrl_stmt (t) || is_ctrl_altering_stmt (t);
2492 /* Add gotos that used to be represented implicitly in the CFG. */
2495 disband_implicit_edges (void)
2498 block_stmt_iterator last;
2504 last = bsi_last (bb);
2505 stmt = last_stmt (bb);
2507 if (stmt && TREE_CODE (stmt) == COND_EXPR)
2509 /* Remove superfluous gotos from COND_EXPR branches. Moved
2510 from cfg_remove_useless_stmts here since it violates the
2511 invariants for tree--cfg correspondence and thus fits better
2512 here where we do it anyway. */
2513 for (e = bb->succ; e; e = e->succ_next)
2515 if (e->dest != bb->next_bb)
2518 if (e->flags & EDGE_TRUE_VALUE)
2519 COND_EXPR_THEN (stmt) = build_empty_stmt ();
2520 else if (e->flags & EDGE_FALSE_VALUE)
2521 COND_EXPR_ELSE (stmt) = build_empty_stmt ();
2524 e->flags |= EDGE_FALLTHRU;
2530 if (stmt && TREE_CODE (stmt) == RETURN_EXPR)
2532 /* Remove the RETURN_EXPR if we may fall though to the exit
2534 gcc_assert (bb->succ);
2535 gcc_assert (!bb->succ->succ_next);
2536 gcc_assert (bb->succ->dest == EXIT_BLOCK_PTR);
2538 if (bb->next_bb == EXIT_BLOCK_PTR
2539 && !TREE_OPERAND (stmt, 0))
2542 bb->succ->flags |= EDGE_FALLTHRU;
2547 /* There can be no fallthru edge if the last statement is a control
2549 if (stmt && is_ctrl_stmt (stmt))
2552 /* Find a fallthru edge and emit the goto if necessary. */
2553 for (e = bb->succ; e; e = e->succ_next)
2554 if (e->flags & EDGE_FALLTHRU)
2557 if (!e || e->dest == bb->next_bb)
2560 gcc_assert (e->dest != EXIT_BLOCK_PTR);
2561 label = tree_block_label (e->dest);
2563 stmt = build1 (GOTO_EXPR, void_type_node, label);
2564 #ifdef USE_MAPPED_LOCATION
2565 SET_EXPR_LOCATION (stmt, e->goto_locus);
2567 SET_EXPR_LOCUS (stmt, e->goto_locus);
2569 bsi_insert_after (&last, stmt, BSI_NEW_STMT);
2570 e->flags &= ~EDGE_FALLTHRU;
2574 /* Remove block annotations and other datastructures. */
2577 delete_tree_cfg_annotations (void)
2580 if (n_basic_blocks > 0)
2581 free_blocks_annotations ();
2583 label_to_block_map = NULL;
2590 /* Return the first statement in basic block BB. */
2593 first_stmt (basic_block bb)
2595 block_stmt_iterator i = bsi_start (bb);
2596 return !bsi_end_p (i) ? bsi_stmt (i) : NULL_TREE;
2600 /* Return the last statement in basic block BB. */
2603 last_stmt (basic_block bb)
2605 block_stmt_iterator b = bsi_last (bb);
2606 return !bsi_end_p (b) ? bsi_stmt (b) : NULL_TREE;
2610 /* Return a pointer to the last statement in block BB. */
2613 last_stmt_ptr (basic_block bb)
2615 block_stmt_iterator last = bsi_last (bb);
2616 return !bsi_end_p (last) ? bsi_stmt_ptr (last) : NULL;
2620 /* Return the last statement of an otherwise empty block. Return NULL
2621 if the block is totally empty, or if it contains more than one
2625 last_and_only_stmt (basic_block bb)
2627 block_stmt_iterator i = bsi_last (bb);
2633 last = bsi_stmt (i);
2638 /* Empty statements should no longer appear in the instruction stream.
2639 Everything that might have appeared before should be deleted by
2640 remove_useless_stmts, and the optimizers should just bsi_remove
2641 instead of smashing with build_empty_stmt.
2643 Thus the only thing that should appear here in a block containing
2644 one executable statement is a label. */
2645 prev = bsi_stmt (i);
2646 if (TREE_CODE (prev) == LABEL_EXPR)
2653 /* Mark BB as the basic block holding statement T. */
2656 set_bb_for_stmt (tree t, basic_block bb)
2658 if (TREE_CODE (t) == PHI_NODE)
2660 else if (TREE_CODE (t) == STATEMENT_LIST)
2662 tree_stmt_iterator i;
2663 for (i = tsi_start (t); !tsi_end_p (i); tsi_next (&i))
2664 set_bb_for_stmt (tsi_stmt (i), bb);
2668 stmt_ann_t ann = get_stmt_ann (t);
2671 /* If the statement is a label, add the label to block-to-labels map
2672 so that we can speed up edge creation for GOTO_EXPRs. */
2673 if (TREE_CODE (t) == LABEL_EXPR)
2677 t = LABEL_EXPR_LABEL (t);
2678 uid = LABEL_DECL_UID (t);
2681 LABEL_DECL_UID (t) = uid = cfun->last_label_uid++;
2682 if (VARRAY_SIZE (label_to_block_map) <= (unsigned) uid)
2683 VARRAY_GROW (label_to_block_map, 3 * uid / 2);
2686 /* We're moving an existing label. Make sure that we've
2687 removed it from the old block. */
2688 gcc_assert (!bb || !VARRAY_BB (label_to_block_map, uid));
2689 VARRAY_BB (label_to_block_map, uid) = bb;
2694 /* Finds iterator for STMT. */
2696 extern block_stmt_iterator
2697 stmt_for_bsi (tree stmt)
2699 block_stmt_iterator bsi;
2701 for (bsi = bsi_start (bb_for_stmt (stmt)); !bsi_end_p (bsi); bsi_next (&bsi))
2702 if (bsi_stmt (bsi) == stmt)
2708 /* Insert statement (or statement list) T before the statement
2709 pointed-to by iterator I. M specifies how to update iterator I
2710 after insertion (see enum bsi_iterator_update). */
2713 bsi_insert_before (block_stmt_iterator *i, tree t, enum bsi_iterator_update m)
2715 set_bb_for_stmt (t, i->bb);
2716 tsi_link_before (&i->tsi, t, m);
2721 /* Insert statement (or statement list) T after the statement
2722 pointed-to by iterator I. M specifies how to update iterator I
2723 after insertion (see enum bsi_iterator_update). */
2726 bsi_insert_after (block_stmt_iterator *i, tree t, enum bsi_iterator_update m)
2728 set_bb_for_stmt (t, i->bb);
2729 tsi_link_after (&i->tsi, t, m);
2734 /* Remove the statement pointed to by iterator I. The iterator is updated
2735 to the next statement. */
2738 bsi_remove (block_stmt_iterator *i)
2740 tree t = bsi_stmt (*i);
2741 set_bb_for_stmt (t, NULL);
2742 tsi_delink (&i->tsi);
2746 /* Move the statement at FROM so it comes right after the statement at TO. */
2749 bsi_move_after (block_stmt_iterator *from, block_stmt_iterator *to)
2751 tree stmt = bsi_stmt (*from);
2753 bsi_insert_after (to, stmt, BSI_SAME_STMT);
2757 /* Move the statement at FROM so it comes right before the statement at TO. */
2760 bsi_move_before (block_stmt_iterator *from, block_stmt_iterator *to)
2762 tree stmt = bsi_stmt (*from);
2764 bsi_insert_before (to, stmt, BSI_SAME_STMT);
2768 /* Move the statement at FROM to the end of basic block BB. */
2771 bsi_move_to_bb_end (block_stmt_iterator *from, basic_block bb)
2773 block_stmt_iterator last = bsi_last (bb);
2775 /* Have to check bsi_end_p because it could be an empty block. */
2776 if (!bsi_end_p (last) && is_ctrl_stmt (bsi_stmt (last)))
2777 bsi_move_before (from, &last);
2779 bsi_move_after (from, &last);
2783 /* Replace the contents of the statement pointed to by iterator BSI
2784 with STMT. If PRESERVE_EH_INFO is true, the exception handling
2785 information of the original statement is preserved. */
2788 bsi_replace (const block_stmt_iterator *bsi, tree stmt, bool preserve_eh_info)
2791 tree orig_stmt = bsi_stmt (*bsi);
2793 SET_EXPR_LOCUS (stmt, EXPR_LOCUS (orig_stmt));
2794 set_bb_for_stmt (stmt, bsi->bb);
2796 /* Preserve EH region information from the original statement, if
2797 requested by the caller. */
2798 if (preserve_eh_info)
2800 eh_region = lookup_stmt_eh_region (orig_stmt);
2802 add_stmt_to_eh_region (stmt, eh_region);
2805 *bsi_stmt_ptr (*bsi) = stmt;
2810 /* Insert the statement pointed-to by BSI into edge E. Every attempt
2811 is made to place the statement in an existing basic block, but
2812 sometimes that isn't possible. When it isn't possible, the edge is
2813 split and the statement is added to the new block.
2815 In all cases, the returned *BSI points to the correct location. The
2816 return value is true if insertion should be done after the location,
2817 or false if it should be done before the location. If new basic block
2818 has to be created, it is stored in *NEW_BB. */
2821 tree_find_edge_insert_loc (edge e, block_stmt_iterator *bsi,
2822 basic_block *new_bb)
2824 basic_block dest, src;
2830 /* If the destination has one predecessor which has no PHI nodes,
2831 insert there. Except for the exit block.
2833 The requirement for no PHI nodes could be relaxed. Basically we
2834 would have to examine the PHIs to prove that none of them used
2835 the value set by the statement we want to insert on E. That
2836 hardly seems worth the effort. */
2837 if (dest->pred->pred_next == NULL
2838 && ! phi_nodes (dest)
2839 && dest != EXIT_BLOCK_PTR)
2841 *bsi = bsi_start (dest);
2842 if (bsi_end_p (*bsi))
2845 /* Make sure we insert after any leading labels. */
2846 tmp = bsi_stmt (*bsi);
2847 while (TREE_CODE (tmp) == LABEL_EXPR)
2850 if (bsi_end_p (*bsi))
2852 tmp = bsi_stmt (*bsi);
2855 if (bsi_end_p (*bsi))
2857 *bsi = bsi_last (dest);
2864 /* If the source has one successor, the edge is not abnormal and
2865 the last statement does not end a basic block, insert there.
2866 Except for the entry block. */
2868 if ((e->flags & EDGE_ABNORMAL) == 0
2869 && src->succ->succ_next == NULL
2870 && src != ENTRY_BLOCK_PTR)
2872 *bsi = bsi_last (src);
2873 if (bsi_end_p (*bsi))
2876 tmp = bsi_stmt (*bsi);
2877 if (!stmt_ends_bb_p (tmp))
2880 /* Insert code just before returning the value. We may need to decompose
2881 the return in the case it contains non-trivial operand. */
2882 if (TREE_CODE (tmp) == RETURN_EXPR)
2884 tree op = TREE_OPERAND (tmp, 0);
2885 if (!is_gimple_val (op))
2887 gcc_assert (TREE_CODE (op) == MODIFY_EXPR);
2888 bsi_insert_before (bsi, op, BSI_NEW_STMT);
2889 TREE_OPERAND (tmp, 0) = TREE_OPERAND (op, 0);
2896 /* Otherwise, create a new basic block, and split this edge. */
2897 dest = split_edge (e);
2905 /* This routine will commit all pending edge insertions, creating any new
2906 basic blocks which are necessary.
2908 If specified, NEW_BLOCKS returns a count of the number of new basic
2909 blocks which were created. */
2912 bsi_commit_edge_inserts (int *new_blocks)
2918 blocks = n_basic_blocks;
2920 bsi_commit_edge_inserts_1 (ENTRY_BLOCK_PTR->succ);
2923 for (e = bb->succ; e; e = e->succ_next)
2924 bsi_commit_edge_inserts_1 (e);
2927 *new_blocks = n_basic_blocks - blocks;
2931 /* Commit insertions pending at edge E. */
2934 bsi_commit_edge_inserts_1 (edge e)
2936 if (PENDING_STMT (e))
2938 block_stmt_iterator bsi;
2939 tree stmt = PENDING_STMT (e);
2941 PENDING_STMT (e) = NULL_TREE;
2943 if (tree_find_edge_insert_loc (e, &bsi, NULL))
2944 bsi_insert_after (&bsi, stmt, BSI_NEW_STMT);
2946 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
2951 /* Add STMT to the pending list of edge E. No actual insertion is
2952 made until a call to bsi_commit_edge_inserts () is made. */
2955 bsi_insert_on_edge (edge e, tree stmt)
2957 append_to_statement_list (stmt, &PENDING_STMT (e));
2960 /* Similar to bsi_insert_on_edge+bsi_commit_edge_inserts. If new block has to
2961 be created, it is returned. */
2964 bsi_insert_on_edge_immediate (edge e, tree stmt)
2966 block_stmt_iterator bsi;
2967 basic_block new_bb = NULL;
2969 gcc_assert (!PENDING_STMT (e));
2971 if (tree_find_edge_insert_loc (e, &bsi, &new_bb))
2972 bsi_insert_after (&bsi, stmt, BSI_NEW_STMT);
2974 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
2979 /*---------------------------------------------------------------------------
2980 Tree specific functions for CFG manipulation
2981 ---------------------------------------------------------------------------*/
2983 /* Split a (typically critical) edge EDGE_IN. Return the new block.
2984 Abort on abnormal edges. */
2987 tree_split_edge (edge edge_in)
2989 basic_block new_bb, after_bb, dest, src;
2994 /* Abnormal edges cannot be split. */
2995 gcc_assert (!(edge_in->flags & EDGE_ABNORMAL));
2998 dest = edge_in->dest;
3000 /* Place the new block in the block list. Try to keep the new block
3001 near its "logical" location. This is of most help to humans looking
3002 at debugging dumps. */
3003 for (e = dest->pred; e; e = e->pred_next)
3004 if (e->src->next_bb == dest)
3007 after_bb = dest->prev_bb;
3009 after_bb = edge_in->src;
3011 new_bb = create_empty_bb (after_bb);
3012 new_bb->frequency = EDGE_FREQUENCY (edge_in);
3013 new_bb->count = edge_in->count;
3014 new_edge = make_edge (new_bb, dest, EDGE_FALLTHRU);
3015 new_edge->probability = REG_BR_PROB_BASE;
3016 new_edge->count = edge_in->count;
3018 /* Find all the PHI arguments on the original edge, and change them to
3019 the new edge. Do it before redirection, so that the argument does not
3021 for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi))
3023 num_elem = PHI_NUM_ARGS (phi);
3024 for (i = 0; i < num_elem; i++)
3025 if (PHI_ARG_EDGE (phi, i) == edge_in)
3027 PHI_ARG_EDGE (phi, i) = new_edge;
3032 e = redirect_edge_and_branch (edge_in, new_bb);
3034 gcc_assert (!PENDING_STMT (edge_in));
3040 /* Return true when BB has label LABEL in it. */
3043 has_label_p (basic_block bb, tree label)
3045 block_stmt_iterator bsi;
3047 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3049 tree stmt = bsi_stmt (bsi);
3051 if (TREE_CODE (stmt) != LABEL_EXPR)
3053 if (LABEL_EXPR_LABEL (stmt) == label)
3060 /* Callback for walk_tree, check that all elements with address taken are
3061 properly noticed as such. */
3064 verify_expr (tree *tp, int *walk_subtrees, void *data ATTRIBUTE_UNUSED)
3071 /* Check operand N for being valid GIMPLE and give error MSG if not.
3072 We check for constants explicitly since they are not considered
3073 gimple invariants if they overflowed. */
3074 #define CHECK_OP(N, MSG) \
3075 do { if (!CONSTANT_CLASS_P (TREE_OPERAND (t, N)) \
3076 && !is_gimple_val (TREE_OPERAND (t, N))) \
3077 { error (MSG); return TREE_OPERAND (t, N); }} while (0)
3079 switch (TREE_CODE (t))
3082 if (SSA_NAME_IN_FREE_LIST (t))
3084 error ("SSA name in freelist but still referenced");
3090 x = TREE_OPERAND (t, 0);
3091 if (TREE_CODE (x) == BIT_FIELD_REF
3092 && is_gimple_reg (TREE_OPERAND (x, 0)))
3094 error ("GIMPLE register modified with BIT_FIELD_REF");
3100 /* Skip any references (they will be checked when we recurse down the
3101 tree) and ensure that any variable used as a prefix is marked
3103 for (x = TREE_OPERAND (t, 0);
3104 (handled_component_p (x)
3105 || TREE_CODE (x) == REALPART_EXPR
3106 || TREE_CODE (x) == IMAGPART_EXPR);
3107 x = TREE_OPERAND (x, 0))
3110 if (TREE_CODE (x) != VAR_DECL && TREE_CODE (x) != PARM_DECL)
3112 if (!TREE_ADDRESSABLE (x))
3114 error ("address taken, but ADDRESSABLE bit not set");
3120 x = TREE_OPERAND (t, 0);
3121 if (TREE_CODE (TREE_TYPE (x)) != BOOLEAN_TYPE)
3123 error ("non-boolean used in condition");
3130 case FIX_TRUNC_EXPR:
3132 case FIX_FLOOR_EXPR:
3133 case FIX_ROUND_EXPR:
3138 case NON_LVALUE_EXPR:
3139 case TRUTH_NOT_EXPR:
3140 CHECK_OP (0, "Invalid operand to unary operator");
3147 case ARRAY_RANGE_REF:
3149 case VIEW_CONVERT_EXPR:
3150 /* We have a nest of references. Verify that each of the operands
3151 that determine where to reference is either a constant or a variable,
3152 verify that the base is valid, and then show we've already checked
3154 while (TREE_CODE (t) == REALPART_EXPR || TREE_CODE (t) == IMAGPART_EXPR
3155 || handled_component_p (t))
3157 if (TREE_CODE (t) == COMPONENT_REF && TREE_OPERAND (t, 2))
3158 CHECK_OP (2, "Invalid COMPONENT_REF offset operator");
3159 else if (TREE_CODE (t) == ARRAY_REF
3160 || TREE_CODE (t) == ARRAY_RANGE_REF)
3162 CHECK_OP (1, "Invalid array index.");
3163 if (TREE_OPERAND (t, 2))
3164 CHECK_OP (2, "Invalid array lower bound.");
3165 if (TREE_OPERAND (t, 3))
3166 CHECK_OP (3, "Invalid array stride.");
3168 else if (TREE_CODE (t) == BIT_FIELD_REF)
3170 CHECK_OP (1, "Invalid operand to BIT_FIELD_REF");
3171 CHECK_OP (2, "Invalid operand to BIT_FIELD_REF");
3174 t = TREE_OPERAND (t, 0);
3177 if (!CONSTANT_CLASS_P (t) && !is_gimple_lvalue (t))
3179 error ("Invalid reference prefix.");
3191 case UNORDERED_EXPR:
3202 case TRUNC_DIV_EXPR:
3204 case FLOOR_DIV_EXPR:
3205 case ROUND_DIV_EXPR:
3206 case TRUNC_MOD_EXPR:
3208 case FLOOR_MOD_EXPR:
3209 case ROUND_MOD_EXPR:
3211 case EXACT_DIV_EXPR:
3221 CHECK_OP (0, "Invalid operand to binary operator");
3222 CHECK_OP (1, "Invalid operand to binary operator");
3234 /* Verify STMT, return true if STMT is not in GIMPLE form.
3235 TODO: Implement type checking. */
3238 verify_stmt (tree stmt, bool last_in_block)
3242 if (!is_gimple_stmt (stmt))
3244 error ("Is not a valid GIMPLE statement.");
3248 addr = walk_tree (&stmt, verify_expr, NULL, NULL);
3251 debug_generic_stmt (addr);
3255 /* If the statement is marked as part of an EH region, then it is
3256 expected that the statement could throw. Verify that when we
3257 have optimizations that simplify statements such that we prove
3258 that they cannot throw, that we update other data structures
3260 if (lookup_stmt_eh_region (stmt) >= 0)
3262 if (!tree_could_throw_p (stmt))
3264 error ("Statement marked for throw, but doesn%'t.");
3267 if (!last_in_block && tree_can_throw_internal (stmt))
3269 error ("Statement marked for throw in middle of block.");
3277 debug_generic_stmt (stmt);
3282 /* Return true when the T can be shared. */
3285 tree_node_can_be_shared (tree t)
3287 if (IS_TYPE_OR_DECL_P (t)
3288 /* We check for constants explicitly since they are not considered
3289 gimple invariants if they overflowed. */
3290 || CONSTANT_CLASS_P (t)
3291 || is_gimple_min_invariant (t)
3292 || TREE_CODE (t) == SSA_NAME)
3295 while (((TREE_CODE (t) == ARRAY_REF || TREE_CODE (t) == ARRAY_RANGE_REF)
3296 /* We check for constants explicitly since they are not considered
3297 gimple invariants if they overflowed. */
3298 && (CONSTANT_CLASS_P (TREE_OPERAND (t, 1))
3299 || is_gimple_min_invariant (TREE_OPERAND (t, 1))))
3300 || (TREE_CODE (t) == COMPONENT_REF
3301 || TREE_CODE (t) == REALPART_EXPR
3302 || TREE_CODE (t) == IMAGPART_EXPR))
3303 t = TREE_OPERAND (t, 0);
3312 /* Called via walk_trees. Verify tree sharing. */
3315 verify_node_sharing (tree * tp, int *walk_subtrees, void *data)
3317 htab_t htab = (htab_t) data;
3320 if (tree_node_can_be_shared (*tp))
3322 *walk_subtrees = false;
3326 slot = htab_find_slot (htab, *tp, INSERT);
3335 /* Verify the GIMPLE statement chain. */
3341 block_stmt_iterator bsi;
3346 timevar_push (TV_TREE_STMT_VERIFY);
3347 htab = htab_create (37, htab_hash_pointer, htab_eq_pointer, NULL);
3354 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
3356 int phi_num_args = PHI_NUM_ARGS (phi);
3358 for (i = 0; i < phi_num_args; i++)
3360 tree t = PHI_ARG_DEF (phi, i);
3363 /* Addressable variables do have SSA_NAMEs but they
3364 are not considered gimple values. */
3365 if (TREE_CODE (t) != SSA_NAME
3366 && TREE_CODE (t) != FUNCTION_DECL
3367 && !is_gimple_val (t))
3369 error ("PHI def is not a GIMPLE value");
3370 debug_generic_stmt (phi);
3371 debug_generic_stmt (t);
3375 addr = walk_tree (&t, verify_expr, NULL, NULL);
3378 debug_generic_stmt (addr);
3382 addr = walk_tree (&t, verify_node_sharing, htab, NULL);
3385 error ("Incorrect sharing of tree nodes");
3386 debug_generic_stmt (phi);
3387 debug_generic_stmt (addr);
3393 for (bsi = bsi_start (bb); !bsi_end_p (bsi); )
3395 tree stmt = bsi_stmt (bsi);
3397 err |= verify_stmt (stmt, bsi_end_p (bsi));
3398 addr = walk_tree (&stmt, verify_node_sharing, htab, NULL);
3401 error ("Incorrect sharing of tree nodes");
3402 debug_generic_stmt (stmt);
3403 debug_generic_stmt (addr);
3410 internal_error ("verify_stmts failed.");
3413 timevar_pop (TV_TREE_STMT_VERIFY);
3417 /* Verifies that the flow information is OK. */
3420 tree_verify_flow_info (void)
3424 block_stmt_iterator bsi;
3428 if (ENTRY_BLOCK_PTR->stmt_list)
3430 error ("ENTRY_BLOCK has a statement list associated with it\n");
3434 if (EXIT_BLOCK_PTR->stmt_list)
3436 error ("EXIT_BLOCK has a statement list associated with it\n");
3440 for (e = EXIT_BLOCK_PTR->pred; e; e = e->pred_next)
3441 if (e->flags & EDGE_FALLTHRU)
3443 error ("Fallthru to exit from bb %d\n", e->src->index);
3449 bool found_ctrl_stmt = false;
3451 /* Skip labels on the start of basic block. */
3452 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3454 if (TREE_CODE (bsi_stmt (bsi)) != LABEL_EXPR)
3457 if (label_to_block (LABEL_EXPR_LABEL (bsi_stmt (bsi))) != bb)
3459 error ("Label %s to block does not match in bb %d\n",
3460 IDENTIFIER_POINTER (DECL_NAME (bsi_stmt (bsi))),
3465 if (decl_function_context (LABEL_EXPR_LABEL (bsi_stmt (bsi)))
3466 != current_function_decl)
3468 error ("Label %s has incorrect context in bb %d\n",
3469 IDENTIFIER_POINTER (DECL_NAME (bsi_stmt (bsi))),
3475 /* Verify that body of basic block BB is free of control flow. */
3476 for (; !bsi_end_p (bsi); bsi_next (&bsi))
3478 tree stmt = bsi_stmt (bsi);
3480 if (found_ctrl_stmt)
3482 error ("Control flow in the middle of basic block %d\n",
3487 if (stmt_ends_bb_p (stmt))
3488 found_ctrl_stmt = true;
3490 if (TREE_CODE (stmt) == LABEL_EXPR)
3492 error ("Label %s in the middle of basic block %d\n",
3493 IDENTIFIER_POINTER (DECL_NAME (stmt)),
3498 bsi = bsi_last (bb);
3499 if (bsi_end_p (bsi))
3502 stmt = bsi_stmt (bsi);
3504 if (is_ctrl_stmt (stmt))
3506 for (e = bb->succ; e; e = e->succ_next)
3507 if (e->flags & EDGE_FALLTHRU)
3509 error ("Fallthru edge after a control statement in bb %d \n",
3515 switch (TREE_CODE (stmt))
3521 if (TREE_CODE (COND_EXPR_THEN (stmt)) != GOTO_EXPR
3522 || TREE_CODE (COND_EXPR_ELSE (stmt)) != GOTO_EXPR)
3524 error ("Structured COND_EXPR at the end of bb %d\n", bb->index);
3528 extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
3530 if (!true_edge || !false_edge
3531 || !(true_edge->flags & EDGE_TRUE_VALUE)
3532 || !(false_edge->flags & EDGE_FALSE_VALUE)
3533 || (true_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL))
3534 || (false_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL))
3535 || bb->succ->succ_next->succ_next)
3537 error ("Wrong outgoing edge flags at end of bb %d\n",
3542 if (!has_label_p (true_edge->dest,
3543 GOTO_DESTINATION (COND_EXPR_THEN (stmt))))
3545 error ("%<then%> label does not match edge at end of bb %d\n",
3550 if (!has_label_p (false_edge->dest,
3551 GOTO_DESTINATION (COND_EXPR_ELSE (stmt))))
3553 error ("%<else%> label does not match edge at end of bb %d\n",
3561 if (simple_goto_p (stmt))
3563 error ("Explicit goto at end of bb %d\n", bb->index);
3568 /* FIXME. We should double check that the labels in the
3569 destination blocks have their address taken. */
3570 for (e = bb->succ; e; e = e->succ_next)
3571 if ((e->flags & (EDGE_FALLTHRU | EDGE_TRUE_VALUE
3572 | EDGE_FALSE_VALUE))
3573 || !(e->flags & EDGE_ABNORMAL))
3575 error ("Wrong outgoing edge flags at end of bb %d\n",
3583 if (!bb->succ || bb->succ->succ_next
3584 || (bb->succ->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL
3585 | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
3587 error ("Wrong outgoing edge flags at end of bb %d\n", bb->index);
3590 if (bb->succ->dest != EXIT_BLOCK_PTR)
3592 error ("Return edge does not point to exit in bb %d\n",
3605 vec = SWITCH_LABELS (stmt);
3606 n = TREE_VEC_LENGTH (vec);
3608 /* Mark all the destination basic blocks. */
3609 for (i = 0; i < n; ++i)
3611 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
3612 basic_block label_bb = label_to_block (lab);
3614 gcc_assert (!label_bb->aux || label_bb->aux == (void *)1);
3615 label_bb->aux = (void *)1;
3618 /* Verify that the case labels are sorted. */
3619 prev = TREE_VEC_ELT (vec, 0);
3620 for (i = 1; i < n - 1; ++i)
3622 tree c = TREE_VEC_ELT (vec, i);
3625 error ("Found default case not at end of case vector");
3629 if (! tree_int_cst_lt (CASE_LOW (prev), CASE_LOW (c)))
3631 error ("Case labels not sorted:\n ");
3632 print_generic_expr (stderr, prev, 0);
3633 fprintf (stderr," is greater than ");
3634 print_generic_expr (stderr, c, 0);
3635 fprintf (stderr," but comes before it.\n");
3640 if (CASE_LOW (TREE_VEC_ELT (vec, n - 1)))
3642 error ("No default case found at end of case vector");
3646 for (e = bb->succ; e; e = e->succ_next)
3650 error ("Extra outgoing edge %d->%d\n",
3651 bb->index, e->dest->index);
3654 e->dest->aux = (void *)2;
3655 if ((e->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL
3656 | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
3658 error ("Wrong outgoing edge flags at end of bb %d\n",
3664 /* Check that we have all of them. */
3665 for (i = 0; i < n; ++i)
3667 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
3668 basic_block label_bb = label_to_block (lab);
3670 if (label_bb->aux != (void *)2)
3672 error ("Missing edge %i->%i\n",
3673 bb->index, label_bb->index);
3678 for (e = bb->succ; e; e = e->succ_next)
3679 e->dest->aux = (void *)0;
3686 if (dom_computed[CDI_DOMINATORS] >= DOM_NO_FAST_QUERY)
3687 verify_dominators (CDI_DOMINATORS);
3693 /* Updates phi nodes after creating forwarder block joined
3694 by edge FALLTHRU. */
3697 tree_make_forwarder_block (edge fallthru)
3700 basic_block dummy, bb;
3701 tree phi, new_phi, var, prev, next;
3703 dummy = fallthru->src;
3704 bb = fallthru->dest;
3706 if (!bb->pred->pred_next)
3709 /* If we redirected a branch we must create new phi nodes at the
3711 for (phi = phi_nodes (dummy); phi; phi = PHI_CHAIN (phi))
3713 var = PHI_RESULT (phi);
3714 new_phi = create_phi_node (var, bb);
3715 SSA_NAME_DEF_STMT (var) = new_phi;
3716 SET_PHI_RESULT (phi, make_ssa_name (SSA_NAME_VAR (var), phi));
3717 add_phi_arg (&new_phi, PHI_RESULT (phi), fallthru);
3720 /* Ensure that the PHI node chain is in the same order. */
3722 for (phi = phi_nodes (bb); phi; phi = next)
3724 next = PHI_CHAIN (phi);
3725 PHI_CHAIN (phi) = prev;
3728 set_phi_nodes (bb, prev);
3730 /* Add the arguments we have stored on edges. */
3731 for (e = bb->pred; e; e = e->pred_next)
3736 for (phi = phi_nodes (bb), var = PENDING_STMT (e);
3738 phi = PHI_CHAIN (phi), var = TREE_CHAIN (var))
3739 add_phi_arg (&phi, TREE_VALUE (var), e);
3741 PENDING_STMT (e) = NULL;
3746 /* Return true if basic block BB does nothing except pass control
3747 flow to another block and that we can safely insert a label at
3748 the start of the successor block. */
3751 tree_forwarder_block_p (basic_block bb)
3753 block_stmt_iterator bsi;
3756 /* If we have already determined that this block is not forwardable,
3757 then no further checks are necessary. */
3758 if (! bb_ann (bb)->forwardable)
3761 /* BB must have a single outgoing normal edge. Otherwise it can not be
3762 a forwarder block. */
3764 || bb->succ->succ_next
3765 || bb->succ->dest == EXIT_BLOCK_PTR
3766 || (bb->succ->flags & EDGE_ABNORMAL)
3767 || bb == ENTRY_BLOCK_PTR)
3769 bb_ann (bb)->forwardable = 0;
3773 /* Successors of the entry block are not forwarders. */
3774 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
3777 bb_ann (bb)->forwardable = 0;
3781 /* BB can not have any PHI nodes. This could potentially be relaxed
3782 early in compilation if we re-rewrote the variables appearing in
3783 any PHI nodes in forwarder blocks. */
3786 bb_ann (bb)->forwardable = 0;
3790 /* Now walk through the statements. We can ignore labels, anything else
3791 means this is not a forwarder block. */
3792 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3794 tree stmt = bsi_stmt (bsi);
3796 switch (TREE_CODE (stmt))
3799 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)))
3804 bb_ann (bb)->forwardable = 0;
3813 /* Thread jumps over empty statements.
3815 This code should _not_ thread over obviously equivalent conditions
3816 as that requires nontrivial updates to the SSA graph. */
3821 edge e, next, last, old;
3822 basic_block bb, dest, tmp, old_dest, curr, dom;
3825 bool retval = false;
3828 bb_ann (bb)->forwardable = 1;
3830 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb)
3832 /* Don't waste time on unreachable blocks. */
3836 /* Nor on forwarders. */
3837 if (tree_forwarder_block_p (bb))
3840 /* This block is now part of a forwarding path, mark it as not
3841 forwardable so that we can detect loops. This bit will be
3843 bb_ann (bb)->forwardable = 0;
3845 /* Examine each of our block's successors to see if it is
3847 for (e = bb->succ; e; e = next)
3851 next = e->succ_next;
3853 /* If the edge is abnormal or its destination is not
3854 forwardable, then there's nothing to do. */
3855 if ((e->flags & EDGE_ABNORMAL)
3856 || !tree_forwarder_block_p (e->dest))
3860 freq = EDGE_FREQUENCY (e);
3862 /* Now walk through as many forwarder block as possible to
3863 find the ultimate destination we want to thread our jump
3865 last = e->dest->succ;
3866 bb_ann (e->dest)->forwardable = 0;
3867 for (dest = e->dest->succ->dest;
3868 tree_forwarder_block_p (dest);
3870 dest = dest->succ->dest)
3872 /* An infinite loop detected. We redirect the edge anyway, so
3873 that the loop is shrunk into single basic block. */
3874 if (!bb_ann (dest)->forwardable)
3877 if (dest->succ->dest == EXIT_BLOCK_PTR)
3880 bb_ann (dest)->forwardable = 0;
3883 /* Reset the forwardable marks to 1. */
3886 tmp = tmp->succ->dest)
3887 bb_ann (tmp)->forwardable = 1;
3889 if (dest == e->dest)
3892 old = find_edge (bb, dest);
3895 /* If there already is an edge, check whether the values
3896 in phi nodes differ. */
3897 if (!phi_alternatives_equal (dest, last, old))
3899 /* The previous block is forwarder. Redirect our jump
3900 to that target instead since we know it has no PHI
3901 nodes that will need updating. */
3904 /* That might mean that no forwarding at all is possible. */
3905 if (dest == e->dest)
3908 old = find_edge (bb, dest);
3912 /* Perform the redirection. */
3915 e = redirect_edge_and_branch (e, dest);
3917 /* Update the profile. */
3918 if (profile_status != PROFILE_ABSENT)
3919 for (curr = old_dest; curr != dest; curr = curr->succ->dest)
3921 curr->frequency -= freq;
3922 if (curr->frequency < 0)
3923 curr->frequency = 0;
3924 curr->count -= count;
3925 if (curr->count < 0)
3927 curr->succ->count -= count;
3928 if (curr->succ->count < 0)
3929 curr->succ->count = 0;
3934 /* Update PHI nodes. We know that the new argument should
3935 have the same value as the argument associated with LAST.
3936 Otherwise we would have changed our target block above. */
3937 for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi))
3939 arg = phi_arg_from_edge (phi, last);
3940 gcc_assert (arg >= 0);
3941 add_phi_arg (&phi, PHI_ARG_DEF (phi, arg), e);
3945 /* Update the dominators. */
3946 if (dom_computed[CDI_DOMINATORS] >= DOM_CONS_OK)
3948 /* Remove the unreachable blocks (observe that if all blocks
3949 were reachable before, only those in the path we threaded
3950 over and did not have any predecessor outside of the path
3951 become unreachable). */
3952 for (; old_dest != dest; old_dest = tmp)
3954 tmp = old_dest->succ->dest;
3959 delete_basic_block (old_dest);
3961 /* If the dominator of the destination was in the path, set its
3962 dominator to the start of the redirected edge. */
3963 if (get_immediate_dominator (CDI_DOMINATORS, old_dest) == NULL)
3964 set_immediate_dominator (CDI_DOMINATORS, old_dest, bb);
3966 /* Now proceed like if we forwarded just over one edge at a time.
3967 Algorithm for forwarding edge S --> A over edge A --> B then
3971 && !dominated_by (S, B))
3972 idom (B) = idom (A);
3973 recount_idom (A); */
3975 for (; old_dest != dest; old_dest = tmp)
3977 tmp = old_dest->succ->dest;
3979 if (get_immediate_dominator (CDI_DOMINATORS, tmp) == old_dest
3980 && !dominated_by_p (CDI_DOMINATORS, bb, tmp))
3982 dom = get_immediate_dominator (CDI_DOMINATORS, old_dest);
3983 set_immediate_dominator (CDI_DOMINATORS, tmp, dom);
3986 dom = recount_dominator (CDI_DOMINATORS, old_dest);
3987 set_immediate_dominator (CDI_DOMINATORS, old_dest, dom);
3992 /* Reset the forwardable bit on our block since it's no longer in
3993 a forwarding chain path. */
3994 bb_ann (bb)->forwardable = 1;
4001 /* Return a non-special label in the head of basic block BLOCK.
4002 Create one if it doesn't exist. */
4005 tree_block_label (basic_block bb)
4007 block_stmt_iterator i, s = bsi_start (bb);
4011 for (i = s; !bsi_end_p (i); first = false, bsi_next (&i))
4013 stmt = bsi_stmt (i);
4014 if (TREE_CODE (stmt) != LABEL_EXPR)
4016 label = LABEL_EXPR_LABEL (stmt);
4017 if (!DECL_NONLOCAL (label))
4020 bsi_move_before (&i, &s);
4025 label = create_artificial_label ();
4026 stmt = build1 (LABEL_EXPR, void_type_node, label);
4027 bsi_insert_before (&s, stmt, BSI_NEW_STMT);
4032 /* Attempt to perform edge redirection by replacing a possibly complex
4033 jump instruction by a goto or by removing the jump completely.
4034 This can apply only if all edges now point to the same block. The
4035 parameters and return values are equivalent to
4036 redirect_edge_and_branch. */
4039 tree_try_redirect_by_replacing_jump (edge e, basic_block target)
4041 basic_block src = e->src;
4043 block_stmt_iterator b;
4046 /* Verify that all targets will be TARGET. */
4047 for (tmp = src->succ; tmp; tmp = tmp->succ_next)
4048 if (tmp->dest != target && tmp != e)
4057 stmt = bsi_stmt (b);
4059 if (TREE_CODE (stmt) == COND_EXPR
4060 || TREE_CODE (stmt) == SWITCH_EXPR)
4063 e = ssa_redirect_edge (e, target);
4064 e->flags = EDGE_FALLTHRU;
4072 /* Redirect E to DEST. Return NULL on failure. Otherwise, return the
4073 edge representing the redirected branch. */
4076 tree_redirect_edge_and_branch (edge e, basic_block dest)
4078 basic_block bb = e->src;
4079 block_stmt_iterator bsi;
4083 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
4086 if (e->src != ENTRY_BLOCK_PTR
4087 && (ret = tree_try_redirect_by_replacing_jump (e, dest)))
4090 if (e->dest == dest)
4093 label = tree_block_label (dest);
4095 bsi = bsi_last (bb);
4096 stmt = bsi_end_p (bsi) ? NULL : bsi_stmt (bsi);
4098 switch (stmt ? TREE_CODE (stmt) : ERROR_MARK)
4101 stmt = (e->flags & EDGE_TRUE_VALUE
4102 ? COND_EXPR_THEN (stmt)
4103 : COND_EXPR_ELSE (stmt));
4104 GOTO_DESTINATION (stmt) = label;
4108 /* No non-abnormal edges should lead from a non-simple goto, and
4109 simple ones should be represented implicitly. */
4114 tree vec = SWITCH_LABELS (stmt);
4115 size_t i, n = TREE_VEC_LENGTH (vec);
4117 for (i = 0; i < n; ++i)
4119 tree elt = TREE_VEC_ELT (vec, i);
4120 if (label_to_block (CASE_LABEL (elt)) == e->dest)
4121 CASE_LABEL (elt) = label;
4128 e->flags |= EDGE_FALLTHRU;
4132 /* Otherwise it must be a fallthru edge, and we don't need to
4133 do anything besides redirecting it. */
4134 gcc_assert (e->flags & EDGE_FALLTHRU);
4138 /* Update/insert PHI nodes as necessary. */
4140 /* Now update the edges in the CFG. */
4141 e = ssa_redirect_edge (e, dest);
4147 /* Simple wrapper, as we can always redirect fallthru edges. */
4150 tree_redirect_edge_and_branch_force (edge e, basic_block dest)
4152 e = tree_redirect_edge_and_branch (e, dest);
4159 /* Splits basic block BB after statement STMT (but at least after the
4160 labels). If STMT is NULL, BB is split just after the labels. */
4163 tree_split_block (basic_block bb, void *stmt)
4165 block_stmt_iterator bsi, bsi_tgt;
4170 new_bb = create_empty_bb (bb);
4172 /* Redirect the outgoing edges. */
4173 new_bb->succ = bb->succ;
4175 for (e = new_bb->succ; e; e = e->succ_next)
4178 if (stmt && TREE_CODE ((tree) stmt) == LABEL_EXPR)
4181 /* Move everything from BSI to the new basic block. */
4182 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4184 act = bsi_stmt (bsi);
4185 if (TREE_CODE (act) == LABEL_EXPR)
4198 bsi_tgt = bsi_start (new_bb);
4199 while (!bsi_end_p (bsi))
4201 act = bsi_stmt (bsi);
4203 bsi_insert_after (&bsi_tgt, act, BSI_NEW_STMT);
4210 /* Moves basic block BB after block AFTER. */
4213 tree_move_block_after (basic_block bb, basic_block after)
4215 if (bb->prev_bb == after)
4219 link_block (bb, after);
4225 /* Return true if basic_block can be duplicated. */
4228 tree_can_duplicate_bb_p (basic_block bb ATTRIBUTE_UNUSED)
4233 /* Create a duplicate of the basic block BB. NOTE: This does not
4234 preserve SSA form. */
4237 tree_duplicate_bb (basic_block bb)
4240 block_stmt_iterator bsi, bsi_tgt;
4242 ssa_op_iter op_iter;
4244 new_bb = create_empty_bb (EXIT_BLOCK_PTR->prev_bb);
4246 /* First copy the phi nodes. We do not copy phi node arguments here,
4247 since the edges are not ready yet. Keep the chain of phi nodes in
4248 the same order, so that we can add them later. */
4249 for (phi = phi_nodes (bb); phi; phi = TREE_CHAIN (phi))
4251 mark_for_rewrite (PHI_RESULT (phi));
4252 create_phi_node (PHI_RESULT (phi), new_bb);
4254 set_phi_nodes (new_bb, nreverse (phi_nodes (new_bb)));
4256 bsi_tgt = bsi_start (new_bb);
4257 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4259 tree stmt = bsi_stmt (bsi);
4262 if (TREE_CODE (stmt) == LABEL_EXPR)
4265 /* Record the definitions. */
4266 get_stmt_operands (stmt);
4268 FOR_EACH_SSA_TREE_OPERAND (val, stmt, op_iter, SSA_OP_ALL_DEFS)
4269 mark_for_rewrite (val);
4271 copy = unshare_expr (stmt);
4273 /* Copy also the virtual operands. */
4274 get_stmt_ann (copy);
4275 copy_virtual_operands (copy, stmt);
4277 bsi_insert_after (&bsi_tgt, copy, BSI_NEW_STMT);
4283 /* Basic block BB_COPY was created by code duplication. Add phi node
4284 arguments for edges going out of BB_COPY. The blocks that were
4285 duplicated have rbi->duplicated set to one. */
4288 add_phi_args_after_copy_bb (basic_block bb_copy)
4290 basic_block bb, dest;
4292 tree phi, phi_copy, phi_next, def;
4294 bb = bb_copy->rbi->original;
4296 for (e_copy = bb_copy->succ; e_copy; e_copy = e_copy->succ_next)
4298 if (!phi_nodes (e_copy->dest))
4301 if (e_copy->dest->rbi->duplicated)
4302 dest = e_copy->dest->rbi->original;
4304 dest = e_copy->dest;
4306 e = find_edge (bb, dest);
4309 /* During loop unrolling the target of the latch edge is copied.
4310 In this case we are not looking for edge to dest, but to
4311 duplicated block whose original was dest. */
4312 for (e = bb->succ; e; e = e->succ_next)
4313 if (e->dest->rbi->duplicated
4314 && e->dest->rbi->original == dest)
4317 gcc_assert (e != NULL);
4320 for (phi = phi_nodes (e->dest), phi_copy = phi_nodes (e_copy->dest);
4322 phi = phi_next, phi_copy = TREE_CHAIN (phi_copy))
4324 phi_next = TREE_CHAIN (phi);
4326 gcc_assert (PHI_RESULT (phi) == PHI_RESULT (phi_copy));
4327 def = PHI_ARG_DEF_FROM_EDGE (phi, e);
4328 add_phi_arg (&phi_copy, def, e_copy);
4333 /* Blocks in REGION_COPY array of length N_REGION were created by
4334 duplication of basic blocks. Add phi node arguments for edges
4335 going from these blocks. */
4338 add_phi_args_after_copy (basic_block *region_copy, unsigned n_region)
4342 for (i = 0; i < n_region; i++)
4343 region_copy[i]->rbi->duplicated = 1;
4345 for (i = 0; i < n_region; i++)
4346 add_phi_args_after_copy_bb (region_copy[i]);
4348 for (i = 0; i < n_region; i++)
4349 region_copy[i]->rbi->duplicated = 0;
4352 /* Maps the old ssa name FROM_NAME to TO_NAME. */
4354 struct ssa_name_map_entry
4360 /* Hash function for ssa_name_map_entry. */
4363 ssa_name_map_entry_hash (const void *entry)
4365 const struct ssa_name_map_entry *en = entry;
4366 return SSA_NAME_VERSION (en->from_name);
4369 /* Equality function for ssa_name_map_entry. */
4372 ssa_name_map_entry_eq (const void *in_table, const void *ssa_name)
4374 const struct ssa_name_map_entry *en = in_table;
4376 return en->from_name == ssa_name;
4379 /* Allocate duplicates of ssa names in list DEFINITIONS and store the mapping
4383 allocate_ssa_names (bitmap definitions, htab_t *map)
4386 struct ssa_name_map_entry *entry;
4392 *map = htab_create (10, ssa_name_map_entry_hash,
4393 ssa_name_map_entry_eq, free);
4394 EXECUTE_IF_SET_IN_BITMAP (definitions, 0, ver, bi)
4396 name = ssa_name (ver);
4397 slot = htab_find_slot_with_hash (*map, name, SSA_NAME_VERSION (name),
4403 entry = xmalloc (sizeof (struct ssa_name_map_entry));
4404 entry->from_name = name;
4407 entry->to_name = duplicate_ssa_name (name, SSA_NAME_DEF_STMT (name));
4411 /* Rewrite the definition DEF in statement STMT to new ssa name as specified
4412 by the mapping MAP. */
4415 rewrite_to_new_ssa_names_def (def_operand_p def, tree stmt, htab_t map)
4417 tree name = DEF_FROM_PTR (def);
4418 struct ssa_name_map_entry *entry;
4420 gcc_assert (TREE_CODE (name) == SSA_NAME);
4422 entry = htab_find_with_hash (map, name, SSA_NAME_VERSION (name));
4426 SET_DEF (def, entry->to_name);
4427 SSA_NAME_DEF_STMT (entry->to_name) = stmt;
4430 /* Rewrite the USE to new ssa name as specified by the mapping MAP. */
4433 rewrite_to_new_ssa_names_use (use_operand_p use, htab_t map)
4435 tree name = USE_FROM_PTR (use);
4436 struct ssa_name_map_entry *entry;
4438 if (TREE_CODE (name) != SSA_NAME)
4441 entry = htab_find_with_hash (map, name, SSA_NAME_VERSION (name));
4445 SET_USE (use, entry->to_name);
4448 /* Rewrite the ssa names in basic block BB to new ones as specified by the
4452 rewrite_to_new_ssa_names_bb (basic_block bb, htab_t map)
4457 block_stmt_iterator bsi;
4461 v_may_def_optype v_may_defs;
4462 v_must_def_optype v_must_defs;
4465 for (e = bb->pred; e; e = e->pred_next)
4466 if (e->flags & EDGE_ABNORMAL)
4469 for (phi = phi_nodes (bb); phi; phi = TREE_CHAIN (phi))
4471 rewrite_to_new_ssa_names_def (PHI_RESULT_PTR (phi), phi, map);
4473 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (PHI_RESULT (phi)) = 1;
4476 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4478 stmt = bsi_stmt (bsi);
4479 get_stmt_operands (stmt);
4480 ann = stmt_ann (stmt);
4482 uses = USE_OPS (ann);
4483 for (i = 0; i < NUM_USES (uses); i++)
4484 rewrite_to_new_ssa_names_use (USE_OP_PTR (uses, i), map);
4486 defs = DEF_OPS (ann);
4487 for (i = 0; i < NUM_DEFS (defs); i++)
4488 rewrite_to_new_ssa_names_def (DEF_OP_PTR (defs, i), stmt, map);
4490 vuses = VUSE_OPS (ann);
4491 for (i = 0; i < NUM_VUSES (vuses); i++)
4492 rewrite_to_new_ssa_names_use (VUSE_OP_PTR (vuses, i), map);
4494 v_may_defs = V_MAY_DEF_OPS (ann);
4495 for (i = 0; i < NUM_V_MAY_DEFS (v_may_defs); i++)
4497 rewrite_to_new_ssa_names_use
4498 (V_MAY_DEF_OP_PTR (v_may_defs, i), map);
4499 rewrite_to_new_ssa_names_def
4500 (V_MAY_DEF_RESULT_PTR (v_may_defs, i), stmt, map);
4503 v_must_defs = V_MUST_DEF_OPS (ann);
4504 for (i = 0; i < NUM_V_MUST_DEFS (v_must_defs); i++)
4505 rewrite_to_new_ssa_names_def
4506 (V_MUST_DEF_OP_PTR (v_must_defs, i), stmt, map);
4509 for (e = bb->succ; e; e = e->succ_next)
4510 for (phi = phi_nodes (e->dest); phi; phi = TREE_CHAIN (phi))
4512 rewrite_to_new_ssa_names_use
4513 (PHI_ARG_DEF_PTR_FROM_EDGE (phi, e), map);
4515 if (e->flags & EDGE_ABNORMAL)
4517 tree op = PHI_ARG_DEF_FROM_EDGE (phi, e);
4518 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op) = 1;
4523 /* Rewrite the ssa names in N_REGION blocks REGION to the new ones as specified
4524 by the mapping MAP. */
4527 rewrite_to_new_ssa_names (basic_block *region, unsigned n_region, htab_t map)
4531 for (r = 0; r < n_region; r++)
4532 rewrite_to_new_ssa_names_bb (region[r], map);
4535 /* Duplicates a REGION (set of N_REGION basic blocks) with just a single
4536 important exit edge EXIT. By important we mean that no SSA name defined
4537 inside region is live over the other exit edges of the region. All entry
4538 edges to the region must go to ENTRY->dest. The edge ENTRY is redirected
4539 to the duplicate of the region. SSA form, dominance and loop information
4540 is updated. The new basic blocks are stored to REGION_COPY in the same
4541 order as they had in REGION, provided that REGION_COPY is not NULL.
4542 The function returns false if it is unable to copy the region,
4546 tree_duplicate_sese_region (edge entry, edge exit,
4547 basic_block *region, unsigned n_region,
4548 basic_block *region_copy)
4550 unsigned i, n_doms, ver;
4551 bool free_region_copy = false, copying_header = false;
4552 struct loop *loop = entry->dest->loop_father;
4557 htab_t ssa_name_map = NULL;
4561 if (!can_copy_bbs_p (region, n_region))
4564 /* Some sanity checking. Note that we do not check for all possible
4565 missuses of the functions. I.e. if you ask to copy something weird,
4566 it will work, but the state of structures probably will not be
4569 for (i = 0; i < n_region; i++)
4571 /* We do not handle subloops, i.e. all the blocks must belong to the
4573 if (region[i]->loop_father != loop)
4576 if (region[i] != entry->dest
4577 && region[i] == loop->header)
4583 /* In case the function is used for loop header copying (which is the primary
4584 use), ensure that EXIT and its copy will be new latch and entry edges. */
4585 if (loop->header == entry->dest)
4587 copying_header = true;
4588 loop->copy = loop->outer;
4590 if (!dominated_by_p (CDI_DOMINATORS, loop->latch, exit->src))
4593 for (i = 0; i < n_region; i++)
4594 if (region[i] != exit->src
4595 && dominated_by_p (CDI_DOMINATORS, region[i], exit->src))
4601 region_copy = xmalloc (sizeof (basic_block) * n_region);
4602 free_region_copy = true;
4605 gcc_assert (!any_marked_for_rewrite_p ());
4607 /* Record blocks outside the region that are duplicated by something
4609 doms = xmalloc (sizeof (basic_block) * n_basic_blocks);
4610 n_doms = get_dominated_by_region (CDI_DOMINATORS, region, n_region, doms);
4612 copy_bbs (region, n_region, region_copy, &exit, 1, &exit_copy, loop);
4613 definitions = marked_ssa_names ();
4617 loop->header = exit->dest;
4618 loop->latch = exit->src;
4621 /* Redirect the entry and add the phi node arguments. */
4622 redirected = redirect_edge_and_branch (entry, entry->dest->rbi->copy);
4623 gcc_assert (redirected != NULL);
4624 for (phi = phi_nodes (entry->dest), var = PENDING_STMT (entry);
4626 phi = TREE_CHAIN (phi), var = TREE_CHAIN (var))
4627 add_phi_arg (&phi, TREE_VALUE (var), entry);
4628 PENDING_STMT (entry) = NULL;
4630 /* Concerning updating of dominators: We must recount dominators
4631 for entry block and its copy. Anything that is outside of the region, but
4632 was dominated by something inside needs recounting as well. */
4633 set_immediate_dominator (CDI_DOMINATORS, entry->dest, entry->src);
4634 doms[n_doms++] = entry->dest->rbi->original;
4635 iterate_fix_dominators (CDI_DOMINATORS, doms, n_doms);
4638 /* Add the other phi node arguments. */
4639 add_phi_args_after_copy (region_copy, n_region);
4641 /* Add phi nodes for definitions at exit. TODO -- once we have immediate
4642 uses, it should be possible to emit phi nodes just for definitions that
4643 are used outside region. */
4644 EXECUTE_IF_SET_IN_BITMAP (definitions, 0, ver, bi)
4646 tree name = ssa_name (ver);
4648 phi = create_phi_node (name, exit->dest);
4649 add_phi_arg (&phi, name, exit);
4650 add_phi_arg (&phi, name, exit_copy);
4652 SSA_NAME_DEF_STMT (name) = phi;
4655 /* And create new definitions inside region and its copy. TODO -- once we
4656 have immediate uses, it might be better to leave definitions in region
4657 unchanged, create new ssa names for phi nodes on exit, and rewrite
4658 the uses, to avoid changing the copied region. */
4659 allocate_ssa_names (definitions, &ssa_name_map);
4660 rewrite_to_new_ssa_names (region, n_region, ssa_name_map);
4661 allocate_ssa_names (definitions, &ssa_name_map);
4662 rewrite_to_new_ssa_names (region_copy, n_region, ssa_name_map);
4663 htab_delete (ssa_name_map);
4665 if (free_region_copy)
4668 unmark_all_for_rewrite ();
4669 BITMAP_XFREE (definitions);
4674 /* Dump FUNCTION_DECL FN to file FILE using FLAGS (see TDF_* in tree.h) */
4677 dump_function_to_file (tree fn, FILE *file, int flags)
4679 tree arg, vars, var;
4680 bool ignore_topmost_bind = false, any_var = false;
4684 fprintf (file, "%s (", lang_hooks.decl_printable_name (fn, 2));
4686 arg = DECL_ARGUMENTS (fn);
4689 print_generic_expr (file, arg, dump_flags);
4690 if (TREE_CHAIN (arg))
4691 fprintf (file, ", ");
4692 arg = TREE_CHAIN (arg);
4694 fprintf (file, ")\n");
4696 if (flags & TDF_RAW)
4698 dump_node (fn, TDF_SLIM | flags, file);
4702 /* When GIMPLE is lowered, the variables are no longer available in
4703 BIND_EXPRs, so display them separately. */
4704 if (cfun && cfun->unexpanded_var_list)
4706 ignore_topmost_bind = true;
4708 fprintf (file, "{\n");
4709 for (vars = cfun->unexpanded_var_list; vars; vars = TREE_CHAIN (vars))
4711 var = TREE_VALUE (vars);
4713 print_generic_decl (file, var, flags);
4714 fprintf (file, "\n");
4720 if (basic_block_info)
4722 /* Make a CFG based dump. */
4723 check_bb_profile (ENTRY_BLOCK_PTR, file);
4724 if (!ignore_topmost_bind)
4725 fprintf (file, "{\n");
4727 if (any_var && n_basic_blocks)
4728 fprintf (file, "\n");
4731 dump_generic_bb (file, bb, 2, flags);
4733 fprintf (file, "}\n");
4734 check_bb_profile (EXIT_BLOCK_PTR, file);
4740 /* Make a tree based dump. */
4741 chain = DECL_SAVED_TREE (fn);
4743 if (TREE_CODE (chain) == BIND_EXPR)
4745 if (ignore_topmost_bind)
4747 chain = BIND_EXPR_BODY (chain);
4755 if (!ignore_topmost_bind)
4756 fprintf (file, "{\n");
4761 fprintf (file, "\n");
4763 print_generic_stmt_indented (file, chain, flags, indent);
4764 if (ignore_topmost_bind)
4765 fprintf (file, "}\n");
4768 fprintf (file, "\n\n");
4772 /* Pretty print of the loops intermediate representation. */
4773 static void print_loop (FILE *, struct loop *, int);
4774 static void print_pred_bbs (FILE *, edge);
4775 static void print_succ_bbs (FILE *, edge);
4778 /* Print the predecessors indexes of edge E on FILE. */
4781 print_pred_bbs (FILE *file, edge e)
4786 else if (e->pred_next == NULL)
4787 fprintf (file, "bb_%d", e->src->index);
4791 fprintf (file, "bb_%d, ", e->src->index);
4792 print_pred_bbs (file, e->pred_next);
4797 /* Print the successors indexes of edge E on FILE. */
4800 print_succ_bbs (FILE *file, edge e)
4804 else if (e->succ_next == NULL)
4805 fprintf (file, "bb_%d", e->dest->index);
4808 fprintf (file, "bb_%d, ", e->dest->index);
4809 print_succ_bbs (file, e->succ_next);
4814 /* Pretty print LOOP on FILE, indented INDENT spaces. */
4817 print_loop (FILE *file, struct loop *loop, int indent)
4825 s_indent = (char *) alloca ((size_t) indent + 1);
4826 memset ((void *) s_indent, ' ', (size_t) indent);
4827 s_indent[indent] = '\0';
4829 /* Print the loop's header. */
4830 fprintf (file, "%sloop_%d\n", s_indent, loop->num);
4832 /* Print the loop's body. */
4833 fprintf (file, "%s{\n", s_indent);
4835 if (bb->loop_father == loop)
4837 /* Print the basic_block's header. */
4838 fprintf (file, "%s bb_%d (preds = {", s_indent, bb->index);
4839 print_pred_bbs (file, bb->pred);
4840 fprintf (file, "}, succs = {");
4841 print_succ_bbs (file, bb->succ);
4842 fprintf (file, "})\n");
4844 /* Print the basic_block's body. */
4845 fprintf (file, "%s {\n", s_indent);
4846 tree_dump_bb (bb, file, indent + 4);
4847 fprintf (file, "%s }\n", s_indent);
4850 print_loop (file, loop->inner, indent + 2);
4851 fprintf (file, "%s}\n", s_indent);
4852 print_loop (file, loop->next, indent);
4856 /* Follow a CFG edge from the entry point of the program, and on entry
4857 of a loop, pretty print the loop structure on FILE. */
4860 print_loop_ir (FILE *file)
4864 bb = BASIC_BLOCK (0);
4865 if (bb && bb->loop_father)
4866 print_loop (file, bb->loop_father, 0);
4870 /* Debugging loops structure at tree level. */
4873 debug_loop_ir (void)
4875 print_loop_ir (stderr);
4879 /* Return true if BB ends with a call, possibly followed by some
4880 instructions that must stay with the call. Return false,
4884 tree_block_ends_with_call_p (basic_block bb)
4886 block_stmt_iterator bsi = bsi_last (bb);
4887 return get_call_expr_in (bsi_stmt (bsi)) != NULL;
4891 /* Return true if BB ends with a conditional branch. Return false,
4895 tree_block_ends_with_condjump_p (basic_block bb)
4897 tree stmt = tsi_stmt (bsi_last (bb).tsi);
4898 return (TREE_CODE (stmt) == COND_EXPR);
4902 /* Return true if we need to add fake edge to exit at statement T.
4903 Helper function for tree_flow_call_edges_add. */
4906 need_fake_edge_p (tree t)
4910 /* NORETURN and LONGJMP calls already have an edge to exit.
4911 CONST, PURE and ALWAYS_RETURN calls do not need one.
4912 We don't currently check for CONST and PURE here, although
4913 it would be a good idea, because those attributes are
4914 figured out from the RTL in mark_constant_function, and
4915 the counter incrementation code from -fprofile-arcs
4916 leads to different results from -fbranch-probabilities. */
4917 call = get_call_expr_in (t);
4919 && !(call_expr_flags (call) &
4920 (ECF_NORETURN | ECF_LONGJMP | ECF_ALWAYS_RETURN)))
4923 if (TREE_CODE (t) == ASM_EXPR
4924 && (ASM_VOLATILE_P (t) || ASM_INPUT_P (t)))
4931 /* Add fake edges to the function exit for any non constant and non
4932 noreturn calls, volatile inline assembly in the bitmap of blocks
4933 specified by BLOCKS or to the whole CFG if BLOCKS is zero. Return
4934 the number of blocks that were split.
4936 The goal is to expose cases in which entering a basic block does
4937 not imply that all subsequent instructions must be executed. */
4940 tree_flow_call_edges_add (sbitmap blocks)
4943 int blocks_split = 0;
4944 int last_bb = last_basic_block;
4945 bool check_last_block = false;
4947 if (n_basic_blocks == 0)
4951 check_last_block = true;
4953 check_last_block = TEST_BIT (blocks, EXIT_BLOCK_PTR->prev_bb->index);
4955 /* In the last basic block, before epilogue generation, there will be
4956 a fallthru edge to EXIT. Special care is required if the last insn
4957 of the last basic block is a call because make_edge folds duplicate
4958 edges, which would result in the fallthru edge also being marked
4959 fake, which would result in the fallthru edge being removed by
4960 remove_fake_edges, which would result in an invalid CFG.
4962 Moreover, we can't elide the outgoing fake edge, since the block
4963 profiler needs to take this into account in order to solve the minimal
4964 spanning tree in the case that the call doesn't return.
4966 Handle this by adding a dummy instruction in a new last basic block. */
4967 if (check_last_block)
4969 basic_block bb = EXIT_BLOCK_PTR->prev_bb;
4970 block_stmt_iterator bsi = bsi_last (bb);
4972 if (!bsi_end_p (bsi))
4975 if (need_fake_edge_p (t))
4979 for (e = bb->succ; e; e = e->succ_next)
4980 if (e->dest == EXIT_BLOCK_PTR)
4982 bsi_insert_on_edge (e, build_empty_stmt ());
4983 bsi_commit_edge_inserts ((int *)NULL);
4989 /* Now add fake edges to the function exit for any non constant
4990 calls since there is no way that we can determine if they will
4992 for (i = 0; i < last_bb; i++)
4994 basic_block bb = BASIC_BLOCK (i);
4995 block_stmt_iterator bsi;
4996 tree stmt, last_stmt;
5001 if (blocks && !TEST_BIT (blocks, i))
5004 bsi = bsi_last (bb);
5005 if (!bsi_end_p (bsi))
5007 last_stmt = bsi_stmt (bsi);
5010 stmt = bsi_stmt (bsi);
5011 if (need_fake_edge_p (stmt))
5014 /* The handling above of the final block before the
5015 epilogue should be enough to verify that there is
5016 no edge to the exit block in CFG already.
5017 Calling make_edge in such case would cause us to
5018 mark that edge as fake and remove it later. */
5019 #ifdef ENABLE_CHECKING
5020 if (stmt == last_stmt)
5021 for (e = bb->succ; e; e = e->succ_next)
5022 gcc_assert (e->dest != EXIT_BLOCK_PTR);
5025 /* Note that the following may create a new basic block
5026 and renumber the existing basic blocks. */
5027 if (stmt != last_stmt)
5029 e = split_block (bb, stmt);
5033 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
5037 while (!bsi_end_p (bsi));
5042 verify_flow_info ();
5044 return blocks_split;
5048 tree_purge_dead_eh_edges (basic_block bb)
5050 bool changed = false;
5052 tree stmt = last_stmt (bb);
5054 if (stmt && tree_can_throw_internal (stmt))
5057 for (e = bb->succ; e ; e = next)
5059 next = e->succ_next;
5060 if (e->flags & EDGE_EH)
5062 ssa_remove_edge (e);
5071 tree_purge_all_dead_eh_edges (bitmap blocks)
5073 bool changed = false;
5077 EXECUTE_IF_SET_IN_BITMAP (blocks, 0, i, bi)
5079 changed |= tree_purge_dead_eh_edges (BASIC_BLOCK (i));
5085 struct cfg_hooks tree_cfg_hooks = {
5087 tree_verify_flow_info,
5088 tree_dump_bb, /* dump_bb */
5089 create_bb, /* create_basic_block */
5090 tree_redirect_edge_and_branch,/* redirect_edge_and_branch */
5091 tree_redirect_edge_and_branch_force,/* redirect_edge_and_branch_force */
5092 remove_bb, /* delete_basic_block */
5093 tree_split_block, /* split_block */
5094 tree_move_block_after, /* move_block_after */
5095 tree_can_merge_blocks_p, /* can_merge_blocks_p */
5096 tree_merge_blocks, /* merge_blocks */
5097 tree_predict_edge, /* predict_edge */
5098 tree_predicted_by_p, /* predicted_by_p */
5099 tree_can_duplicate_bb_p, /* can_duplicate_block_p */
5100 tree_duplicate_bb, /* duplicate_block */
5101 tree_split_edge, /* split_edge */
5102 tree_make_forwarder_block, /* make_forward_block */
5103 NULL, /* tidy_fallthru_edge */
5104 tree_block_ends_with_call_p, /* block_ends_with_call_p */
5105 tree_block_ends_with_condjump_p, /* block_ends_with_condjump_p */
5106 tree_flow_call_edges_add /* flow_call_edges_add */
5110 /* Split all critical edges. */
5113 split_critical_edges (void)
5120 for (e = bb->succ; e ; e = e->succ_next)
5121 if (EDGE_CRITICAL_P (e) && !(e->flags & EDGE_ABNORMAL))
5128 struct tree_opt_pass pass_split_crit_edges =
5130 "crited", /* name */
5132 split_critical_edges, /* execute */
5135 0, /* static_pass_number */
5136 TV_TREE_SPLIT_EDGES, /* tv_id */
5137 PROP_cfg, /* properties required */
5138 PROP_no_crit_edges, /* properties_provided */
5139 0, /* properties_destroyed */
5140 0, /* todo_flags_start */
5141 TODO_dump_func, /* todo_flags_finish */
5146 /* Return EXP if it is a valid GIMPLE rvalue, else gimplify it into
5147 a temporary, make sure and register it to be renamed if necessary,
5148 and finally return the temporary. Put the statements to compute
5149 EXP before the current statement in BSI. */
5152 gimplify_val (block_stmt_iterator *bsi, tree type, tree exp)
5154 tree t, new_stmt, orig_stmt;
5156 if (is_gimple_val (exp))
5159 t = make_rename_temp (type, NULL);
5160 new_stmt = build (MODIFY_EXPR, type, t, exp);
5162 orig_stmt = bsi_stmt (*bsi);
5163 SET_EXPR_LOCUS (new_stmt, EXPR_LOCUS (orig_stmt));
5164 TREE_BLOCK (new_stmt) = TREE_BLOCK (orig_stmt);
5166 bsi_insert_before (bsi, new_stmt, BSI_SAME_STMT);
5171 /* Build a ternary operation and gimplify it. Emit code before BSI.
5172 Return the gimple_val holding the result. */
5175 gimplify_build3 (block_stmt_iterator *bsi, enum tree_code code,
5176 tree type, tree a, tree b, tree c)
5180 ret = fold (build3 (code, type, a, b, c));
5183 return gimplify_val (bsi, type, ret);
5186 /* Build a binary operation and gimplify it. Emit code before BSI.
5187 Return the gimple_val holding the result. */
5190 gimplify_build2 (block_stmt_iterator *bsi, enum tree_code code,
5191 tree type, tree a, tree b)
5195 ret = fold (build2 (code, type, a, b));
5198 return gimplify_val (bsi, type, ret);
5201 /* Build a unary operation and gimplify it. Emit code before BSI.
5202 Return the gimple_val holding the result. */
5205 gimplify_build1 (block_stmt_iterator *bsi, enum tree_code code, tree type,
5210 ret = fold (build1 (code, type, a));
5213 return gimplify_val (bsi, type, ret);
5218 /* Emit return warnings. */
5221 execute_warn_function_return (void)
5223 #ifdef USE_MAPPED_LOCATION
5224 source_location location;
5231 if (warn_missing_noreturn
5232 && !TREE_THIS_VOLATILE (cfun->decl)
5233 && EXIT_BLOCK_PTR->pred == NULL
5234 && !lang_hooks.function.missing_noreturn_ok_p (cfun->decl))
5235 warning ("%Jfunction might be possible candidate for "
5236 "attribute %<noreturn%>",
5239 /* If we have a path to EXIT, then we do return. */
5240 if (TREE_THIS_VOLATILE (cfun->decl)
5241 && EXIT_BLOCK_PTR->pred != NULL)
5243 #ifdef USE_MAPPED_LOCATION
5244 location = UNKNOWN_LOCATION;
5248 for (e = EXIT_BLOCK_PTR->pred; e ; e = e->pred_next)
5250 last = last_stmt (e->src);
5251 if (TREE_CODE (last) == RETURN_EXPR
5252 #ifdef USE_MAPPED_LOCATION
5253 && (location = EXPR_LOCATION (last)) != UNKNOWN_LOCATION)
5255 && (locus = EXPR_LOCUS (last)) != NULL)
5259 #ifdef USE_MAPPED_LOCATION
5260 if (location == UNKNOWN_LOCATION)
5261 location = cfun->function_end_locus;
5262 warning ("%H%<noreturn%> function does return", &location);
5265 locus = &cfun->function_end_locus;
5266 warning ("%H%<noreturn%> function does return", locus);
5270 /* If we see "return;" in some basic block, then we do reach the end
5271 without returning a value. */
5272 else if (warn_return_type
5273 && EXIT_BLOCK_PTR->pred != NULL
5274 && !VOID_TYPE_P (TREE_TYPE (TREE_TYPE (cfun->decl))))
5276 for (e = EXIT_BLOCK_PTR->pred; e ; e = e->pred_next)
5278 tree last = last_stmt (e->src);
5279 if (TREE_CODE (last) == RETURN_EXPR
5280 && TREE_OPERAND (last, 0) == NULL)
5282 #ifdef USE_MAPPED_LOCATION
5283 location = EXPR_LOCATION (last);
5284 if (location == UNKNOWN_LOCATION)
5285 location = cfun->function_end_locus;
5286 warning ("%Hcontrol reaches end of non-void function", &location);
5288 locus = EXPR_LOCUS (last);
5290 locus = &cfun->function_end_locus;
5291 warning ("%Hcontrol reaches end of non-void function", locus);
5300 /* Given a basic block B which ends with a conditional and has
5301 precisely two successors, determine which of the edges is taken if
5302 the conditional is true and which is taken if the conditional is
5303 false. Set TRUE_EDGE and FALSE_EDGE appropriately. */
5306 extract_true_false_edges_from_block (basic_block b,
5312 if (e->flags & EDGE_TRUE_VALUE)
5315 *false_edge = e->succ_next;
5320 *true_edge = e->succ_next;
5324 struct tree_opt_pass pass_warn_function_return =
5328 execute_warn_function_return, /* execute */
5331 0, /* static_pass_number */
5333 PROP_cfg, /* properties_required */
5334 0, /* properties_provided */
5335 0, /* properties_destroyed */
5336 0, /* todo_flags_start */
5337 0, /* todo_flags_finish */
5341 #include "gt-tree-cfg.h"