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"
47 /* This file contains functions for building the Control Flow Graph (CFG)
48 for a function tree. */
50 /* Local declarations. */
52 /* Initial capacity for the basic block array. */
53 static const int initial_cfg_capacity = 20;
55 /* Mapping of labels to their associated blocks. This can greatly speed up
56 building of the CFG in code with lots of gotos. */
57 static GTY(()) varray_type label_to_block_map;
62 long num_merged_labels;
65 static struct cfg_stats_d cfg_stats;
67 /* Nonzero if we found a computed goto while building basic blocks. */
68 static bool found_computed_goto;
70 /* Basic blocks and flowgraphs. */
71 static basic_block create_bb (void *, void *, basic_block);
72 static void create_block_annotation (basic_block);
73 static void free_blocks_annotations (void);
74 static void clear_blocks_annotations (void);
75 static void make_blocks (tree);
76 static void factor_computed_gotos (void);
79 static void make_edges (void);
80 static void make_ctrl_stmt_edges (basic_block);
81 static void make_exit_edges (basic_block);
82 static void make_cond_expr_edges (basic_block);
83 static void make_switch_expr_edges (basic_block);
84 static void make_goto_expr_edges (basic_block);
85 static edge tree_redirect_edge_and_branch (edge, basic_block);
86 static edge tree_try_redirect_by_replacing_jump (edge, basic_block);
87 static void split_critical_edges (void);
89 /* Various helpers. */
90 static inline bool stmt_starts_bb_p (tree, tree);
91 static int tree_verify_flow_info (void);
92 static void tree_make_forwarder_block (edge);
93 static bool thread_jumps (void);
94 static bool tree_forwarder_block_p (basic_block);
95 static void bsi_commit_edge_inserts_1 (edge e);
96 static void tree_cfg2vcg (FILE *);
98 /* Flowgraph optimization and cleanup. */
99 static void tree_merge_blocks (basic_block, basic_block);
100 static bool tree_can_merge_blocks_p (basic_block, basic_block);
101 static void remove_bb (basic_block);
102 static bool cleanup_control_flow (void);
103 static bool cleanup_control_expr_graph (basic_block, block_stmt_iterator);
104 static edge find_taken_edge_cond_expr (basic_block, tree);
105 static edge find_taken_edge_switch_expr (basic_block, tree);
106 static tree find_case_label_for_value (tree, tree);
107 static bool phi_alternatives_equal (basic_block, edge, edge);
110 /*---------------------------------------------------------------------------
112 ---------------------------------------------------------------------------*/
114 /* Entry point to the CFG builder for trees. TP points to the list of
115 statements to be added to the flowgraph. */
118 build_tree_cfg (tree *tp)
120 /* Register specific tree functions. */
121 tree_register_cfg_hooks ();
123 /* Initialize rbi_pool. */
126 /* Initialize the basic block array. */
128 profile_status = PROFILE_ABSENT;
130 last_basic_block = 0;
131 VARRAY_BB_INIT (basic_block_info, initial_cfg_capacity, "basic_block_info");
132 memset ((void *) &cfg_stats, 0, sizeof (cfg_stats));
134 /* Build a mapping of labels to their associated blocks. */
135 VARRAY_BB_INIT (label_to_block_map, initial_cfg_capacity,
136 "label to block map");
138 ENTRY_BLOCK_PTR->next_bb = EXIT_BLOCK_PTR;
139 EXIT_BLOCK_PTR->prev_bb = ENTRY_BLOCK_PTR;
141 found_computed_goto = 0;
144 /* Computed gotos are hell to deal with, especially if there are
145 lots of them with a large number of destinations. So we factor
146 them to a common computed goto location before we build the
147 edge list. After we convert back to normal form, we will un-factor
148 the computed gotos since factoring introduces an unwanted jump. */
149 if (found_computed_goto)
150 factor_computed_gotos ();
152 /* Make sure there is always at least one block, even if its empty. */
153 if (n_basic_blocks == 0)
154 create_empty_bb (ENTRY_BLOCK_PTR);
156 create_block_annotation (ENTRY_BLOCK_PTR);
157 create_block_annotation (EXIT_BLOCK_PTR);
159 /* Adjust the size of the array. */
160 VARRAY_GROW (basic_block_info, n_basic_blocks);
162 /* To speed up statement iterator walks, we first purge dead labels. */
163 cleanup_dead_labels ();
165 /* Group case nodes to reduce the number of edges.
166 We do this after cleaning up dead labels because otherwise we miss
167 a lot of obvious case merging opportunities. */
168 group_case_labels ();
170 /* Create the edges of the flowgraph. */
173 /* Debugging dumps. */
175 /* Write the flowgraph to a VCG file. */
177 int local_dump_flags;
178 FILE *dump_file = dump_begin (TDI_vcg, &local_dump_flags);
181 tree_cfg2vcg (dump_file);
182 dump_end (TDI_vcg, dump_file);
186 /* Dump a textual representation of the flowgraph. */
188 dump_tree_cfg (dump_file, dump_flags);
192 execute_build_cfg (void)
194 build_tree_cfg (&DECL_SAVED_TREE (current_function_decl));
197 struct tree_opt_pass pass_build_cfg =
201 execute_build_cfg, /* execute */
204 0, /* static_pass_number */
205 TV_TREE_CFG, /* tv_id */
206 PROP_gimple_leh, /* properties_required */
207 PROP_cfg, /* properties_provided */
208 0, /* properties_destroyed */
209 0, /* todo_flags_start */
210 TODO_verify_stmts, /* todo_flags_finish */
214 /* Search the CFG for any computed gotos. If found, factor them to a
215 common computed goto site. Also record the location of that site so
216 that we can un-factor the gotos after we have converted back to
220 factor_computed_gotos (void)
223 tree factored_label_decl = NULL;
225 tree factored_computed_goto_label = NULL;
226 tree factored_computed_goto = NULL;
228 /* We know there are one or more computed gotos in this function.
229 Examine the last statement in each basic block to see if the block
230 ends with a computed goto. */
234 block_stmt_iterator bsi = bsi_last (bb);
239 last = bsi_stmt (bsi);
241 /* Ignore the computed goto we create when we factor the original
243 if (last == factored_computed_goto)
246 /* If the last statement is a computed goto, factor it. */
247 if (computed_goto_p (last))
251 /* The first time we find a computed goto we need to create
252 the factored goto block and the variable each original
253 computed goto will use for their goto destination. */
254 if (! factored_computed_goto)
256 basic_block new_bb = create_empty_bb (bb);
257 block_stmt_iterator new_bsi = bsi_start (new_bb);
259 /* Create the destination of the factored goto. Each original
260 computed goto will put its desired destination into this
261 variable and jump to the label we create immediately
263 var = create_tmp_var (ptr_type_node, "gotovar");
265 /* Build a label for the new block which will contain the
266 factored computed goto. */
267 factored_label_decl = create_artificial_label ();
268 factored_computed_goto_label
269 = build1 (LABEL_EXPR, void_type_node, factored_label_decl);
270 bsi_insert_after (&new_bsi, factored_computed_goto_label,
273 /* Build our new computed goto. */
274 factored_computed_goto = build1 (GOTO_EXPR, void_type_node, var);
275 bsi_insert_after (&new_bsi, factored_computed_goto,
279 /* Copy the original computed goto's destination into VAR. */
280 assignment = build (MODIFY_EXPR, ptr_type_node,
281 var, GOTO_DESTINATION (last));
282 bsi_insert_before (&bsi, assignment, BSI_SAME_STMT);
284 /* And re-vector the computed goto to the new destination. */
285 GOTO_DESTINATION (last) = factored_label_decl;
291 /* Create annotations for a single basic block. */
294 create_block_annotation (basic_block bb)
296 /* Verify that the tree_annotations field is clear. */
297 gcc_assert (!bb->tree_annotations);
298 bb->tree_annotations = ggc_alloc_cleared (sizeof (struct bb_ann_d));
302 /* Free the annotations for all the basic blocks. */
304 static void free_blocks_annotations (void)
306 clear_blocks_annotations ();
310 /* Clear the annotations for all the basic blocks. */
313 clear_blocks_annotations (void)
317 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb)
318 bb->tree_annotations = NULL;
322 /* Build a flowgraph for the statement_list STMT_LIST. */
325 make_blocks (tree stmt_list)
327 tree_stmt_iterator i = tsi_start (stmt_list);
329 bool start_new_block = true;
330 bool first_stmt_of_list = true;
331 basic_block bb = ENTRY_BLOCK_PTR;
333 while (!tsi_end_p (i))
340 /* If the statement starts a new basic block or if we have determined
341 in a previous pass that we need to create a new block for STMT, do
343 if (start_new_block || stmt_starts_bb_p (stmt, prev_stmt))
345 if (!first_stmt_of_list)
346 stmt_list = tsi_split_statement_list_before (&i);
347 bb = create_basic_block (stmt_list, NULL, bb);
348 start_new_block = false;
351 /* Now add STMT to BB and create the subgraphs for special statement
353 set_bb_for_stmt (stmt, bb);
355 if (computed_goto_p (stmt))
356 found_computed_goto = true;
358 /* If STMT is a basic block terminator, set START_NEW_BLOCK for the
360 if (stmt_ends_bb_p (stmt))
361 start_new_block = true;
364 first_stmt_of_list = false;
369 /* Create and return a new empty basic block after bb AFTER. */
372 create_bb (void *h, void *e, basic_block after)
378 /* Create and initialize a new basic block. */
380 memset (bb, 0, sizeof (*bb));
382 bb->index = last_basic_block;
384 bb->stmt_list = h ? h : alloc_stmt_list ();
386 /* Add the new block to the linked list of blocks. */
387 link_block (bb, after);
389 /* Grow the basic block array if needed. */
390 if ((size_t) last_basic_block == VARRAY_SIZE (basic_block_info))
392 size_t new_size = last_basic_block + (last_basic_block + 3) / 4;
393 VARRAY_GROW (basic_block_info, new_size);
396 /* Add the newly created block to the array. */
397 BASIC_BLOCK (last_basic_block) = bb;
399 create_block_annotation (bb);
404 initialize_bb_rbi (bb);
409 /*---------------------------------------------------------------------------
411 ---------------------------------------------------------------------------*/
413 /* Join all the blocks in the flowgraph. */
420 /* Create an edge from entry to the first block with executable
422 make_edge (ENTRY_BLOCK_PTR, BASIC_BLOCK (0), EDGE_FALLTHRU);
424 /* Traverse basic block array placing edges. */
427 tree first = first_stmt (bb);
428 tree last = last_stmt (bb);
432 /* Edges for statements that always alter flow control. */
433 if (is_ctrl_stmt (last))
434 make_ctrl_stmt_edges (bb);
436 /* Edges for statements that sometimes alter flow control. */
437 if (is_ctrl_altering_stmt (last))
438 make_exit_edges (bb);
441 /* Finally, if no edges were created above, this is a regular
442 basic block that only needs a fallthru edge. */
443 if (bb->succ == NULL)
444 make_edge (bb, bb->next_bb, EDGE_FALLTHRU);
447 /* We do not care about fake edges, so remove any that the CFG
448 builder inserted for completeness. */
449 remove_fake_exit_edges ();
451 /* Clean up the graph and warn for unreachable code. */
456 /* Create edges for control statement at basic block BB. */
459 make_ctrl_stmt_edges (basic_block bb)
461 tree last = last_stmt (bb);
464 switch (TREE_CODE (last))
467 make_goto_expr_edges (bb);
471 make_edge (bb, EXIT_BLOCK_PTR, 0);
475 make_cond_expr_edges (bb);
479 make_switch_expr_edges (bb);
483 make_eh_edges (last);
484 /* Yet another NORETURN hack. */
485 if (bb->succ == NULL)
486 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
495 /* Create exit edges for statements in block BB that alter the flow of
496 control. Statements that alter the control flow are 'goto', 'return'
497 and calls to non-returning functions. */
500 make_exit_edges (basic_block bb)
502 tree last = last_stmt (bb), op;
505 switch (TREE_CODE (last))
508 /* If this function receives a nonlocal goto, then we need to
509 make edges from this call site to all the nonlocal goto
511 if (TREE_SIDE_EFFECTS (last)
512 && current_function_has_nonlocal_label)
513 make_goto_expr_edges (bb);
515 /* If this statement has reachable exception handlers, then
516 create abnormal edges to them. */
517 make_eh_edges (last);
519 /* Some calls are known not to return. For such calls we create
522 We really need to revamp how we build edges so that it's not
523 such a bloody pain to avoid creating edges for this case since
524 all we do is remove these edges when we're done building the
526 if (call_expr_flags (last) & (ECF_NORETURN | ECF_LONGJMP))
528 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
532 /* Don't forget the fall-thru edge. */
533 make_edge (bb, bb->next_bb, EDGE_FALLTHRU);
537 /* A MODIFY_EXPR may have a CALL_EXPR on its RHS and the CALL_EXPR
538 may have an abnormal edge. Search the RHS for this case and
539 create any required edges. */
540 op = get_call_expr_in (last);
541 if (op && TREE_SIDE_EFFECTS (op)
542 && current_function_has_nonlocal_label)
543 make_goto_expr_edges (bb);
545 make_eh_edges (last);
546 make_edge (bb, bb->next_bb, EDGE_FALLTHRU);
555 /* Create the edges for a COND_EXPR starting at block BB.
556 At this point, both clauses must contain only simple gotos. */
559 make_cond_expr_edges (basic_block bb)
561 tree entry = last_stmt (bb);
562 basic_block then_bb, else_bb;
563 tree then_label, else_label;
566 gcc_assert (TREE_CODE (entry) == COND_EXPR);
568 /* Entry basic blocks for each component. */
569 then_label = GOTO_DESTINATION (COND_EXPR_THEN (entry));
570 else_label = GOTO_DESTINATION (COND_EXPR_ELSE (entry));
571 then_bb = label_to_block (then_label);
572 else_bb = label_to_block (else_label);
574 make_edge (bb, then_bb, EDGE_TRUE_VALUE);
575 make_edge (bb, else_bb, EDGE_FALSE_VALUE);
579 /* Create the edges for a SWITCH_EXPR starting at block BB.
580 At this point, the switch body has been lowered and the
581 SWITCH_LABELS filled in, so this is in effect a multi-way branch. */
584 make_switch_expr_edges (basic_block bb)
586 tree entry = last_stmt (bb);
590 vec = SWITCH_LABELS (entry);
591 n = TREE_VEC_LENGTH (vec);
593 for (i = 0; i < n; ++i)
595 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
596 basic_block label_bb = label_to_block (lab);
597 make_edge (bb, label_bb, 0);
602 /* Return the basic block holding label DEST. */
605 label_to_block (tree dest)
607 int uid = LABEL_DECL_UID (dest);
609 /* We would die hard when faced by undefined label. Emit label to
610 very first basic block. This will hopefully make even the dataflow
611 and undefined variable warnings quite right. */
612 if ((errorcount || sorrycount) && uid < 0)
614 block_stmt_iterator bsi = bsi_start (BASIC_BLOCK (0));
617 stmt = build1 (LABEL_EXPR, void_type_node, dest);
618 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
619 uid = LABEL_DECL_UID (dest);
621 return VARRAY_BB (label_to_block_map, uid);
625 /* Create edges for a goto statement at block BB. */
628 make_goto_expr_edges (basic_block bb)
631 basic_block target_bb;
633 block_stmt_iterator last = bsi_last (bb);
635 goto_t = bsi_stmt (last);
637 /* If the last statement is not a GOTO (i.e., it is a RETURN_EXPR,
638 CALL_EXPR or MODIFY_EXPR), then the edge is an abnormal edge resulting
639 from a nonlocal goto. */
640 if (TREE_CODE (goto_t) != GOTO_EXPR)
642 dest = error_mark_node;
647 dest = GOTO_DESTINATION (goto_t);
650 /* A GOTO to a local label creates normal edges. */
651 if (simple_goto_p (goto_t))
653 edge e = make_edge (bb, label_to_block (dest), EDGE_FALLTHRU);
654 #ifdef USE_MAPPED_LOCATION
655 e->goto_locus = EXPR_LOCATION (goto_t);
657 e->goto_locus = EXPR_LOCUS (goto_t);
663 /* Nothing more to do for nonlocal gotos. */
664 if (TREE_CODE (dest) == LABEL_DECL)
667 /* Computed gotos remain. */
670 /* Look for the block starting with the destination label. In the
671 case of a computed goto, make an edge to any label block we find
673 FOR_EACH_BB (target_bb)
675 block_stmt_iterator bsi;
677 for (bsi = bsi_start (target_bb); !bsi_end_p (bsi); bsi_next (&bsi))
679 tree target = bsi_stmt (bsi);
681 if (TREE_CODE (target) != LABEL_EXPR)
685 /* Computed GOTOs. Make an edge to every label block that has
686 been marked as a potential target for a computed goto. */
687 (FORCED_LABEL (LABEL_EXPR_LABEL (target)) && for_call == 0)
688 /* Nonlocal GOTO target. Make an edge to every label block
689 that has been marked as a potential target for a nonlocal
691 || (DECL_NONLOCAL (LABEL_EXPR_LABEL (target)) && for_call == 1))
693 make_edge (bb, target_bb, EDGE_ABNORMAL);
699 /* Degenerate case of computed goto with no labels. */
700 if (!for_call && !bb->succ)
701 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
705 /*---------------------------------------------------------------------------
707 ---------------------------------------------------------------------------*/
709 /* Remove unreachable blocks and other miscellaneous clean up work. */
712 cleanup_tree_cfg (void)
714 bool something_changed = true;
717 timevar_push (TV_TREE_CLEANUP_CFG);
719 /* These three transformations can cascade, so we iterate on them until
721 while (something_changed)
723 something_changed = cleanup_control_flow ();
724 something_changed |= delete_unreachable_blocks ();
725 something_changed |= thread_jumps ();
726 retval |= something_changed;
729 /* Merging the blocks creates no new opportunities for the other
730 optimizations, so do it here. */
735 #ifdef ENABLE_CHECKING
738 timevar_pop (TV_TREE_CLEANUP_CFG);
743 /* Cleanup useless labels in basic blocks. This is something we wish
744 to do early because it allows us to group case labels before creating
745 the edges for the CFG, and it speeds up block statement iterators in
747 We only run this pass once, running it more than once is probably not
750 /* A map from basic block index to the leading label of that block. */
751 static tree *label_for_bb;
753 /* Callback for for_each_eh_region. Helper for cleanup_dead_labels. */
755 update_eh_label (struct eh_region *region)
757 tree old_label = get_eh_region_tree_label (region);
761 basic_block bb = label_to_block (old_label);
763 /* ??? After optimizing, there may be EH regions with labels
764 that have already been removed from the function body, so
765 there is no basic block for them. */
769 new_label = label_for_bb[bb->index];
770 set_eh_region_tree_label (region, new_label);
774 /* Given LABEL return the first label in the same basic block. */
776 main_block_label (tree label)
778 basic_block bb = label_to_block (label);
780 /* label_to_block possibly inserted undefined label into the chain. */
781 if (!label_for_bb[bb->index])
782 label_for_bb[bb->index] = label;
783 return label_for_bb[bb->index];
786 /* Cleanup redundant labels. This is a three-steo process:
787 1) Find the leading label for each block.
788 2) Redirect all references to labels to the leading labels.
789 3) Cleanup all useless labels. */
792 cleanup_dead_labels (void)
795 label_for_bb = xcalloc (last_basic_block, sizeof (tree));
797 /* Find a suitable label for each block. We use the first user-defined
798 label is there is one, or otherwise just the first label we see. */
801 block_stmt_iterator i;
803 for (i = bsi_start (bb); !bsi_end_p (i); bsi_next (&i))
805 tree label, stmt = bsi_stmt (i);
807 if (TREE_CODE (stmt) != LABEL_EXPR)
810 label = LABEL_EXPR_LABEL (stmt);
812 /* If we have not yet seen a label for the current block,
813 remember this one and see if there are more labels. */
814 if (! label_for_bb[bb->index])
816 label_for_bb[bb->index] = label;
820 /* If we did see a label for the current block already, but it
821 is an artificially created label, replace it if the current
822 label is a user defined label. */
823 if (! DECL_ARTIFICIAL (label)
824 && DECL_ARTIFICIAL (label_for_bb[bb->index]))
826 label_for_bb[bb->index] = label;
832 /* Now redirect all jumps/branches to the selected label.
833 First do so for each block ending in a control statement. */
836 tree stmt = last_stmt (bb);
840 switch (TREE_CODE (stmt))
844 tree true_branch, false_branch;
846 true_branch = COND_EXPR_THEN (stmt);
847 false_branch = COND_EXPR_ELSE (stmt);
849 GOTO_DESTINATION (true_branch)
850 = main_block_label (GOTO_DESTINATION (true_branch));
851 GOTO_DESTINATION (false_branch)
852 = main_block_label (GOTO_DESTINATION (false_branch));
860 tree vec = SWITCH_LABELS (stmt);
861 size_t n = TREE_VEC_LENGTH (vec);
863 /* Replace all destination labels. */
864 for (i = 0; i < n; ++i)
865 CASE_LABEL (TREE_VEC_ELT (vec, i))
866 = main_block_label (CASE_LABEL (TREE_VEC_ELT (vec, i)));
871 /* We have to handle GOTO_EXPRs until they're removed, and we don't
872 remove them until after we've created the CFG edges. */
874 if (! computed_goto_p (stmt))
876 GOTO_DESTINATION (stmt)
877 = main_block_label (GOTO_DESTINATION (stmt));
886 for_each_eh_region (update_eh_label);
888 /* Finally, purge dead labels. All user-defined labels and labels that
889 can be the target of non-local gotos are preserved. */
892 block_stmt_iterator i;
893 tree label_for_this_bb = label_for_bb[bb->index];
895 if (! label_for_this_bb)
898 for (i = bsi_start (bb); !bsi_end_p (i); )
900 tree label, stmt = bsi_stmt (i);
902 if (TREE_CODE (stmt) != LABEL_EXPR)
905 label = LABEL_EXPR_LABEL (stmt);
907 if (label == label_for_this_bb
908 || ! DECL_ARTIFICIAL (label)
909 || DECL_NONLOCAL (label))
919 /* Look for blocks ending in a multiway branch (a SWITCH_EXPR in GIMPLE),
920 and scan the sorted vector of cases. Combine the ones jumping to the
922 Eg. three separate entries 1: 2: 3: become one entry 1..3: */
925 group_case_labels (void)
931 tree stmt = last_stmt (bb);
932 if (stmt && TREE_CODE (stmt) == SWITCH_EXPR)
934 tree labels = SWITCH_LABELS (stmt);
935 int old_size = TREE_VEC_LENGTH (labels);
936 int i, j, new_size = old_size;
937 tree default_label = TREE_VEC_ELT (labels, old_size - 1);
939 /* Look for possible opportunities to merge cases.
940 Ignore the last element of the label vector because it
941 must be the default case. */
943 while (i < old_size - 2)
945 tree base_case, base_label, base_high, type;
946 base_case = TREE_VEC_ELT (labels, i);
948 gcc_assert (base_case);
949 base_label = CASE_LABEL (base_case);
951 /* Discard cases that have the same destination as the
953 if (base_label == default_label)
955 TREE_VEC_ELT (labels, i) = NULL_TREE;
960 type = TREE_TYPE (CASE_LOW (base_case));
961 base_high = CASE_HIGH (base_case) ?
962 CASE_HIGH (base_case) : CASE_LOW (base_case);
964 /* Try to merge case labels. Break out when we reach the end
965 of the label vector or when we cannot merge the next case
966 label with the current one. */
967 while (i < old_size - 2)
969 tree merge_case = TREE_VEC_ELT (labels, ++i);
970 tree merge_label = CASE_LABEL (merge_case);
971 tree t = int_const_binop (PLUS_EXPR, base_high,
972 integer_one_node, 1);
974 /* Merge the cases if they jump to the same place,
975 and their ranges are consecutive. */
976 if (merge_label == base_label
977 && tree_int_cst_equal (CASE_LOW (merge_case), t))
979 base_high = CASE_HIGH (merge_case) ?
980 CASE_HIGH (merge_case) : CASE_LOW (merge_case);
981 CASE_HIGH (base_case) = base_high;
982 TREE_VEC_ELT (labels, i) = NULL_TREE;
990 /* Compress the case labels in the label vector, and adjust the
991 length of the vector. */
992 for (i = 0, j = 0; i < new_size; i++)
994 while (! TREE_VEC_ELT (labels, j))
996 TREE_VEC_ELT (labels, i) = TREE_VEC_ELT (labels, j++);
998 TREE_VEC_LENGTH (labels) = new_size;
1003 /* Checks whether we can merge block B into block A. */
1006 tree_can_merge_blocks_p (basic_block a, basic_block b)
1009 block_stmt_iterator bsi;
1012 || a->succ->succ_next)
1015 if (a->succ->flags & EDGE_ABNORMAL)
1018 if (a->succ->dest != b)
1021 if (b == EXIT_BLOCK_PTR)
1024 if (b->pred->pred_next)
1027 /* If A ends by a statement causing exceptions or something similar, we
1028 cannot merge the blocks. */
1029 stmt = last_stmt (a);
1030 if (stmt && stmt_ends_bb_p (stmt))
1033 /* Do not allow a block with only a non-local label to be merged. */
1034 if (stmt && TREE_CODE (stmt) == LABEL_EXPR
1035 && DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)))
1038 /* There may be no phi nodes at the start of b. Most of these degenerate
1039 phi nodes should be cleaned up by kill_redundant_phi_nodes. */
1043 /* Do not remove user labels. */
1044 for (bsi = bsi_start (b); !bsi_end_p (bsi); bsi_next (&bsi))
1046 stmt = bsi_stmt (bsi);
1047 if (TREE_CODE (stmt) != LABEL_EXPR)
1049 if (!DECL_ARTIFICIAL (LABEL_EXPR_LABEL (stmt)))
1057 /* Merge block B into block A. */
1060 tree_merge_blocks (basic_block a, basic_block b)
1062 block_stmt_iterator bsi;
1063 tree_stmt_iterator last;
1066 fprintf (dump_file, "Merging blocks %d and %d\n", a->index, b->index);
1068 /* Ensure that B follows A. */
1069 move_block_after (b, a);
1071 gcc_assert (a->succ->flags & EDGE_FALLTHRU);
1072 gcc_assert (!last_stmt (a) || !stmt_ends_bb_p (last_stmt (a)));
1074 /* Remove labels from B and set bb_for_stmt to A for other statements. */
1075 for (bsi = bsi_start (b); !bsi_end_p (bsi);)
1077 if (TREE_CODE (bsi_stmt (bsi)) == LABEL_EXPR)
1081 set_bb_for_stmt (bsi_stmt (bsi), a);
1086 /* Merge the chains. */
1087 last = tsi_last (a->stmt_list);
1088 tsi_link_after (&last, b->stmt_list, TSI_NEW_STMT);
1089 b->stmt_list = NULL;
1093 /* Walk the function tree removing unnecessary statements.
1095 * Empty statement nodes are removed
1097 * Unnecessary TRY_FINALLY and TRY_CATCH blocks are removed
1099 * Unnecessary COND_EXPRs are removed
1101 * Some unnecessary BIND_EXPRs are removed
1103 Clearly more work could be done. The trick is doing the analysis
1104 and removal fast enough to be a net improvement in compile times.
1106 Note that when we remove a control structure such as a COND_EXPR
1107 BIND_EXPR, or TRY block, we will need to repeat this optimization pass
1108 to ensure we eliminate all the useless code. */
1119 static void remove_useless_stmts_1 (tree *, struct rus_data *);
1122 remove_useless_stmts_warn_notreached (tree stmt)
1124 if (EXPR_HAS_LOCATION (stmt))
1126 location_t loc = EXPR_LOCATION (stmt);
1127 warning ("%Hwill never be executed", &loc);
1131 switch (TREE_CODE (stmt))
1133 case STATEMENT_LIST:
1135 tree_stmt_iterator i;
1136 for (i = tsi_start (stmt); !tsi_end_p (i); tsi_next (&i))
1137 if (remove_useless_stmts_warn_notreached (tsi_stmt (i)))
1143 if (remove_useless_stmts_warn_notreached (COND_EXPR_COND (stmt)))
1145 if (remove_useless_stmts_warn_notreached (COND_EXPR_THEN (stmt)))
1147 if (remove_useless_stmts_warn_notreached (COND_EXPR_ELSE (stmt)))
1151 case TRY_FINALLY_EXPR:
1152 case TRY_CATCH_EXPR:
1153 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt, 0)))
1155 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt, 1)))
1160 return remove_useless_stmts_warn_notreached (CATCH_BODY (stmt));
1161 case EH_FILTER_EXPR:
1162 return remove_useless_stmts_warn_notreached (EH_FILTER_FAILURE (stmt));
1164 return remove_useless_stmts_warn_notreached (BIND_EXPR_BLOCK (stmt));
1167 /* Not a live container. */
1175 remove_useless_stmts_cond (tree *stmt_p, struct rus_data *data)
1177 tree then_clause, else_clause, cond;
1178 bool save_has_label, then_has_label, else_has_label;
1180 save_has_label = data->has_label;
1181 data->has_label = false;
1182 data->last_goto = NULL;
1184 remove_useless_stmts_1 (&COND_EXPR_THEN (*stmt_p), data);
1186 then_has_label = data->has_label;
1187 data->has_label = false;
1188 data->last_goto = NULL;
1190 remove_useless_stmts_1 (&COND_EXPR_ELSE (*stmt_p), data);
1192 else_has_label = data->has_label;
1193 data->has_label = save_has_label | then_has_label | else_has_label;
1196 then_clause = COND_EXPR_THEN (*stmt_p);
1197 else_clause = COND_EXPR_ELSE (*stmt_p);
1198 cond = COND_EXPR_COND (*stmt_p);
1200 /* If neither arm does anything at all, we can remove the whole IF. */
1201 if (!TREE_SIDE_EFFECTS (then_clause) && !TREE_SIDE_EFFECTS (else_clause))
1203 *stmt_p = build_empty_stmt ();
1204 data->repeat = true;
1207 /* If there are no reachable statements in an arm, then we can
1208 zap the entire conditional. */
1209 else if (integer_nonzerop (cond) && !else_has_label)
1211 if (warn_notreached)
1212 remove_useless_stmts_warn_notreached (else_clause);
1213 *stmt_p = then_clause;
1214 data->repeat = true;
1216 else if (integer_zerop (cond) && !then_has_label)
1218 if (warn_notreached)
1219 remove_useless_stmts_warn_notreached (then_clause);
1220 *stmt_p = else_clause;
1221 data->repeat = true;
1224 /* Check a couple of simple things on then/else with single stmts. */
1227 tree then_stmt = expr_only (then_clause);
1228 tree else_stmt = expr_only (else_clause);
1230 /* Notice branches to a common destination. */
1231 if (then_stmt && else_stmt
1232 && TREE_CODE (then_stmt) == GOTO_EXPR
1233 && TREE_CODE (else_stmt) == GOTO_EXPR
1234 && (GOTO_DESTINATION (then_stmt) == GOTO_DESTINATION (else_stmt)))
1236 *stmt_p = then_stmt;
1237 data->repeat = true;
1240 /* If the THEN/ELSE clause merely assigns a value to a variable or
1241 parameter which is already known to contain that value, then
1242 remove the useless THEN/ELSE clause. */
1243 else if (TREE_CODE (cond) == VAR_DECL || TREE_CODE (cond) == PARM_DECL)
1246 && TREE_CODE (else_stmt) == MODIFY_EXPR
1247 && TREE_OPERAND (else_stmt, 0) == cond
1248 && integer_zerop (TREE_OPERAND (else_stmt, 1)))
1249 COND_EXPR_ELSE (*stmt_p) = alloc_stmt_list ();
1251 else if ((TREE_CODE (cond) == EQ_EXPR || TREE_CODE (cond) == NE_EXPR)
1252 && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL
1253 || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL)
1254 && TREE_CONSTANT (TREE_OPERAND (cond, 1)))
1256 tree stmt = (TREE_CODE (cond) == EQ_EXPR
1257 ? then_stmt : else_stmt);
1258 tree *location = (TREE_CODE (cond) == EQ_EXPR
1259 ? &COND_EXPR_THEN (*stmt_p)
1260 : &COND_EXPR_ELSE (*stmt_p));
1263 && TREE_CODE (stmt) == MODIFY_EXPR
1264 && TREE_OPERAND (stmt, 0) == TREE_OPERAND (cond, 0)
1265 && TREE_OPERAND (stmt, 1) == TREE_OPERAND (cond, 1))
1266 *location = alloc_stmt_list ();
1270 /* Protect GOTOs in the arm of COND_EXPRs from being removed. They
1271 would be re-introduced during lowering. */
1272 data->last_goto = NULL;
1277 remove_useless_stmts_tf (tree *stmt_p, struct rus_data *data)
1279 bool save_may_branch, save_may_throw;
1280 bool this_may_branch, this_may_throw;
1282 /* Collect may_branch and may_throw information for the body only. */
1283 save_may_branch = data->may_branch;
1284 save_may_throw = data->may_throw;
1285 data->may_branch = false;
1286 data->may_throw = false;
1287 data->last_goto = NULL;
1289 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 0), data);
1291 this_may_branch = data->may_branch;
1292 this_may_throw = data->may_throw;
1293 data->may_branch |= save_may_branch;
1294 data->may_throw |= save_may_throw;
1295 data->last_goto = NULL;
1297 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 1), data);
1299 /* If the body is empty, then we can emit the FINALLY block without
1300 the enclosing TRY_FINALLY_EXPR. */
1301 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 0)))
1303 *stmt_p = TREE_OPERAND (*stmt_p, 1);
1304 data->repeat = true;
1307 /* If the handler is empty, then we can emit the TRY block without
1308 the enclosing TRY_FINALLY_EXPR. */
1309 else if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 1)))
1311 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1312 data->repeat = true;
1315 /* If the body neither throws, nor branches, then we can safely
1316 string the TRY and FINALLY blocks together. */
1317 else if (!this_may_branch && !this_may_throw)
1319 tree stmt = *stmt_p;
1320 *stmt_p = TREE_OPERAND (stmt, 0);
1321 append_to_statement_list (TREE_OPERAND (stmt, 1), stmt_p);
1322 data->repeat = true;
1328 remove_useless_stmts_tc (tree *stmt_p, struct rus_data *data)
1330 bool save_may_throw, this_may_throw;
1331 tree_stmt_iterator i;
1334 /* Collect may_throw information for the body only. */
1335 save_may_throw = data->may_throw;
1336 data->may_throw = false;
1337 data->last_goto = NULL;
1339 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 0), data);
1341 this_may_throw = data->may_throw;
1342 data->may_throw = save_may_throw;
1344 /* If the body cannot throw, then we can drop the entire TRY_CATCH_EXPR. */
1345 if (!this_may_throw)
1347 if (warn_notreached)
1348 remove_useless_stmts_warn_notreached (TREE_OPERAND (*stmt_p, 1));
1349 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1350 data->repeat = true;
1354 /* Process the catch clause specially. We may be able to tell that
1355 no exceptions propagate past this point. */
1357 this_may_throw = true;
1358 i = tsi_start (TREE_OPERAND (*stmt_p, 1));
1359 stmt = tsi_stmt (i);
1360 data->last_goto = NULL;
1362 switch (TREE_CODE (stmt))
1365 for (; !tsi_end_p (i); tsi_next (&i))
1367 stmt = tsi_stmt (i);
1368 /* If we catch all exceptions, then the body does not
1369 propagate exceptions past this point. */
1370 if (CATCH_TYPES (stmt) == NULL)
1371 this_may_throw = false;
1372 data->last_goto = NULL;
1373 remove_useless_stmts_1 (&CATCH_BODY (stmt), data);
1377 case EH_FILTER_EXPR:
1378 if (EH_FILTER_MUST_NOT_THROW (stmt))
1379 this_may_throw = false;
1380 else if (EH_FILTER_TYPES (stmt) == NULL)
1381 this_may_throw = false;
1382 remove_useless_stmts_1 (&EH_FILTER_FAILURE (stmt), data);
1386 /* Otherwise this is a cleanup. */
1387 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 1), data);
1389 /* If the cleanup is empty, then we can emit the TRY block without
1390 the enclosing TRY_CATCH_EXPR. */
1391 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 1)))
1393 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1394 data->repeat = true;
1398 data->may_throw |= this_may_throw;
1403 remove_useless_stmts_bind (tree *stmt_p, struct rus_data *data)
1407 /* First remove anything underneath the BIND_EXPR. */
1408 remove_useless_stmts_1 (&BIND_EXPR_BODY (*stmt_p), data);
1410 /* If the BIND_EXPR has no variables, then we can pull everything
1411 up one level and remove the BIND_EXPR, unless this is the toplevel
1412 BIND_EXPR for the current function or an inlined function.
1414 When this situation occurs we will want to apply this
1415 optimization again. */
1416 block = BIND_EXPR_BLOCK (*stmt_p);
1417 if (BIND_EXPR_VARS (*stmt_p) == NULL_TREE
1418 && *stmt_p != DECL_SAVED_TREE (current_function_decl)
1420 || ! BLOCK_ABSTRACT_ORIGIN (block)
1421 || (TREE_CODE (BLOCK_ABSTRACT_ORIGIN (block))
1424 *stmt_p = BIND_EXPR_BODY (*stmt_p);
1425 data->repeat = true;
1431 remove_useless_stmts_goto (tree *stmt_p, struct rus_data *data)
1433 tree dest = GOTO_DESTINATION (*stmt_p);
1435 data->may_branch = true;
1436 data->last_goto = NULL;
1438 /* Record the last goto expr, so that we can delete it if unnecessary. */
1439 if (TREE_CODE (dest) == LABEL_DECL)
1440 data->last_goto = stmt_p;
1445 remove_useless_stmts_label (tree *stmt_p, struct rus_data *data)
1447 tree label = LABEL_EXPR_LABEL (*stmt_p);
1449 data->has_label = true;
1451 /* We do want to jump across non-local label receiver code. */
1452 if (DECL_NONLOCAL (label))
1453 data->last_goto = NULL;
1455 else if (data->last_goto && GOTO_DESTINATION (*data->last_goto) == label)
1457 *data->last_goto = build_empty_stmt ();
1458 data->repeat = true;
1461 /* ??? Add something here to delete unused labels. */
1465 /* If the function is "const" or "pure", then clear TREE_SIDE_EFFECTS on its
1466 decl. This allows us to eliminate redundant or useless
1467 calls to "const" functions.
1469 Gimplifier already does the same operation, but we may notice functions
1470 being const and pure once their calls has been gimplified, so we need
1471 to update the flag. */
1474 update_call_expr_flags (tree call)
1476 tree decl = get_callee_fndecl (call);
1479 if (call_expr_flags (call) & (ECF_CONST | ECF_PURE))
1480 TREE_SIDE_EFFECTS (call) = 0;
1481 if (TREE_NOTHROW (decl))
1482 TREE_NOTHROW (call) = 1;
1486 /* T is CALL_EXPR. Set current_function_calls_* flags. */
1489 notice_special_calls (tree t)
1491 int flags = call_expr_flags (t);
1493 if (flags & ECF_MAY_BE_ALLOCA)
1494 current_function_calls_alloca = true;
1495 if (flags & ECF_RETURNS_TWICE)
1496 current_function_calls_setjmp = true;
1500 /* Clear flags set by notice_special_calls. Used by dead code removal
1501 to update the flags. */
1504 clear_special_calls (void)
1506 current_function_calls_alloca = false;
1507 current_function_calls_setjmp = false;
1512 remove_useless_stmts_1 (tree *tp, struct rus_data *data)
1516 switch (TREE_CODE (t))
1519 remove_useless_stmts_cond (tp, data);
1522 case TRY_FINALLY_EXPR:
1523 remove_useless_stmts_tf (tp, data);
1526 case TRY_CATCH_EXPR:
1527 remove_useless_stmts_tc (tp, data);
1531 remove_useless_stmts_bind (tp, data);
1535 remove_useless_stmts_goto (tp, data);
1539 remove_useless_stmts_label (tp, data);
1544 data->last_goto = NULL;
1545 data->may_branch = true;
1550 data->last_goto = NULL;
1551 notice_special_calls (t);
1552 update_call_expr_flags (t);
1553 if (tree_could_throw_p (t))
1554 data->may_throw = true;
1558 data->last_goto = NULL;
1560 op = get_call_expr_in (t);
1563 update_call_expr_flags (op);
1564 notice_special_calls (op);
1566 if (tree_could_throw_p (t))
1567 data->may_throw = true;
1570 case STATEMENT_LIST:
1572 tree_stmt_iterator i = tsi_start (t);
1573 while (!tsi_end_p (i))
1576 if (IS_EMPTY_STMT (t))
1582 remove_useless_stmts_1 (tsi_stmt_ptr (i), data);
1585 if (TREE_CODE (t) == STATEMENT_LIST)
1587 tsi_link_before (&i, t, TSI_SAME_STMT);
1597 data->last_goto = NULL;
1601 data->last_goto = NULL;
1607 remove_useless_stmts (void)
1609 struct rus_data data;
1611 clear_special_calls ();
1615 memset (&data, 0, sizeof (data));
1616 remove_useless_stmts_1 (&DECL_SAVED_TREE (current_function_decl), &data);
1618 while (data.repeat);
1622 struct tree_opt_pass pass_remove_useless_stmts =
1624 "useless", /* name */
1626 remove_useless_stmts, /* execute */
1629 0, /* static_pass_number */
1631 PROP_gimple_any, /* properties_required */
1632 0, /* properties_provided */
1633 0, /* properties_destroyed */
1634 0, /* todo_flags_start */
1635 TODO_dump_func, /* todo_flags_finish */
1640 /* Remove obviously useless statements in basic block BB. */
1643 cfg_remove_useless_stmts_bb (basic_block bb)
1645 block_stmt_iterator bsi;
1646 tree stmt = NULL_TREE;
1647 tree cond, var = NULL_TREE, val = NULL_TREE;
1648 struct var_ann_d *ann;
1650 /* Check whether we come here from a condition, and if so, get the
1653 || bb->pred->pred_next
1654 || !(bb->pred->flags & (EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
1657 cond = COND_EXPR_COND (last_stmt (bb->pred->src));
1659 if (TREE_CODE (cond) == VAR_DECL || TREE_CODE (cond) == PARM_DECL)
1662 val = (bb->pred->flags & EDGE_FALSE_VALUE
1663 ? boolean_false_node : boolean_true_node);
1665 else if (TREE_CODE (cond) == TRUTH_NOT_EXPR
1666 && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL
1667 || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL))
1669 var = TREE_OPERAND (cond, 0);
1670 val = (bb->pred->flags & EDGE_FALSE_VALUE
1671 ? boolean_true_node : boolean_false_node);
1675 if (bb->pred->flags & EDGE_FALSE_VALUE)
1676 cond = invert_truthvalue (cond);
1677 if (TREE_CODE (cond) == EQ_EXPR
1678 && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL
1679 || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL)
1680 && (TREE_CODE (TREE_OPERAND (cond, 1)) == VAR_DECL
1681 || TREE_CODE (TREE_OPERAND (cond, 1)) == PARM_DECL
1682 || TREE_CONSTANT (TREE_OPERAND (cond, 1))))
1684 var = TREE_OPERAND (cond, 0);
1685 val = TREE_OPERAND (cond, 1);
1691 /* Only work for normal local variables. */
1692 ann = var_ann (var);
1695 || TREE_ADDRESSABLE (var))
1698 if (! TREE_CONSTANT (val))
1700 ann = var_ann (val);
1703 || TREE_ADDRESSABLE (val))
1707 /* Ignore floating point variables, since comparison behaves weird for
1709 if (FLOAT_TYPE_P (TREE_TYPE (var)))
1712 for (bsi = bsi_start (bb); !bsi_end_p (bsi);)
1714 stmt = bsi_stmt (bsi);
1716 /* If the THEN/ELSE clause merely assigns a value to a variable/parameter
1717 which is already known to contain that value, then remove the useless
1718 THEN/ELSE clause. */
1719 if (TREE_CODE (stmt) == MODIFY_EXPR
1720 && TREE_OPERAND (stmt, 0) == var
1721 && operand_equal_p (val, TREE_OPERAND (stmt, 1), 0))
1727 /* Invalidate the var if we encounter something that could modify it.
1728 Likewise for the value it was previously set to. Note that we only
1729 consider values that are either a VAR_DECL or PARM_DECL so we
1730 can test for conflict very simply. */
1731 if (TREE_CODE (stmt) == ASM_EXPR
1732 || (TREE_CODE (stmt) == MODIFY_EXPR
1733 && (TREE_OPERAND (stmt, 0) == var
1734 || TREE_OPERAND (stmt, 0) == val)))
1742 /* A CFG-aware version of remove_useless_stmts. */
1745 cfg_remove_useless_stmts (void)
1749 #ifdef ENABLE_CHECKING
1750 verify_flow_info ();
1755 cfg_remove_useless_stmts_bb (bb);
1760 /* Remove PHI nodes associated with basic block BB and all edges out of BB. */
1763 remove_phi_nodes_and_edges_for_unreachable_block (basic_block bb)
1767 /* Since this block is no longer reachable, we can just delete all
1768 of its PHI nodes. */
1769 phi = phi_nodes (bb);
1772 tree next = PHI_CHAIN (phi);
1773 remove_phi_node (phi, NULL_TREE, bb);
1777 /* Remove edges to BB's successors. */
1778 while (bb->succ != NULL)
1779 ssa_remove_edge (bb->succ);
1783 /* Remove statements of basic block BB. */
1786 remove_bb (basic_block bb)
1788 block_stmt_iterator i;
1789 source_locus loc = 0;
1793 fprintf (dump_file, "Removing basic block %d\n", bb->index);
1794 if (dump_flags & TDF_DETAILS)
1796 dump_bb (bb, dump_file, 0);
1797 fprintf (dump_file, "\n");
1801 /* Remove all the instructions in the block. */
1802 for (i = bsi_start (bb); !bsi_end_p (i); bsi_remove (&i))
1804 tree stmt = bsi_stmt (i);
1805 release_defs (stmt);
1807 set_bb_for_stmt (stmt, NULL);
1809 /* Don't warn for removed gotos. Gotos are often removed due to
1810 jump threading, thus resulting in bogus warnings. Not great,
1811 since this way we lose warnings for gotos in the original
1812 program that are indeed unreachable. */
1813 if (TREE_CODE (stmt) != GOTO_EXPR && EXPR_HAS_LOCATION (stmt) && !loc)
1814 #ifdef USE_MAPPED_LOCATION
1815 loc = EXPR_LOCATION (stmt);
1817 loc = EXPR_LOCUS (stmt);
1821 /* If requested, give a warning that the first statement in the
1822 block is unreachable. We walk statements backwards in the
1823 loop above, so the last statement we process is the first statement
1825 if (warn_notreached && loc)
1826 #ifdef USE_MAPPED_LOCATION
1827 warning ("%Hwill never be executed", &loc);
1829 warning ("%Hwill never be executed", loc);
1832 remove_phi_nodes_and_edges_for_unreachable_block (bb);
1836 /* Examine BB to determine if it is a forwarding block (a block which only
1837 transfers control to a new destination). If BB is a forwarding block,
1838 then return the edge leading to the ultimate destination. */
1841 tree_block_forwards_to (basic_block bb)
1843 block_stmt_iterator bsi;
1844 bb_ann_t ann = bb_ann (bb);
1847 /* If this block is not forwardable, then avoid useless work. */
1848 if (! ann->forwardable)
1851 /* Set this block to not be forwardable. This prevents infinite loops since
1852 any block currently under examination is considered non-forwardable. */
1853 ann->forwardable = 0;
1855 /* No forwarding is possible if this block is a special block (ENTRY/EXIT),
1856 this block has more than one successor, this block's single successor is
1857 reached via an abnormal edge, this block has phi nodes, or this block's
1858 single successor has phi nodes. */
1859 if (bb == EXIT_BLOCK_PTR
1860 || bb == ENTRY_BLOCK_PTR
1862 || bb->succ->succ_next
1863 || bb->succ->dest == EXIT_BLOCK_PTR
1864 || (bb->succ->flags & EDGE_ABNORMAL) != 0
1866 || phi_nodes (bb->succ->dest))
1869 /* Walk past any labels at the start of this block. */
1870 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
1872 stmt = bsi_stmt (bsi);
1873 if (TREE_CODE (stmt) != LABEL_EXPR)
1877 /* If we reached the end of this block we may be able to optimize this
1879 if (bsi_end_p (bsi))
1883 /* Recursive call to pick up chains of forwarding blocks. */
1884 dest = tree_block_forwards_to (bb->succ->dest);
1886 /* If none found, we forward to bb->succ at minimum. */
1890 ann->forwardable = 1;
1894 /* No forwarding possible. */
1899 /* Try to remove superfluous control structures. */
1902 cleanup_control_flow (void)
1905 block_stmt_iterator bsi;
1906 bool retval = false;
1911 bsi = bsi_last (bb);
1913 if (bsi_end_p (bsi))
1916 stmt = bsi_stmt (bsi);
1917 if (TREE_CODE (stmt) == COND_EXPR
1918 || TREE_CODE (stmt) == SWITCH_EXPR)
1919 retval |= cleanup_control_expr_graph (bb, bsi);
1925 /* Disconnect an unreachable block in the control expression starting
1929 cleanup_control_expr_graph (basic_block bb, block_stmt_iterator bsi)
1932 bool retval = false;
1933 tree expr = bsi_stmt (bsi), val;
1935 if (bb->succ->succ_next)
1939 switch (TREE_CODE (expr))
1942 val = COND_EXPR_COND (expr);
1946 val = SWITCH_COND (expr);
1947 if (TREE_CODE (val) != INTEGER_CST)
1955 taken_edge = find_taken_edge (bb, val);
1959 /* Remove all the edges except the one that is always executed. */
1960 for (e = bb->succ; e; e = next)
1962 next = e->succ_next;
1963 if (e != taken_edge)
1965 taken_edge->probability += e->probability;
1966 taken_edge->count += e->count;
1967 ssa_remove_edge (e);
1971 if (taken_edge->probability > REG_BR_PROB_BASE)
1972 taken_edge->probability = REG_BR_PROB_BASE;
1975 taken_edge = bb->succ;
1978 taken_edge->flags = EDGE_FALLTHRU;
1980 /* We removed some paths from the cfg. */
1981 if (dom_computed[CDI_DOMINATORS] >= DOM_CONS_OK)
1982 dom_computed[CDI_DOMINATORS] = DOM_CONS_OK;
1988 /* Given a control block BB and a predicate VAL, return the edge that
1989 will be taken out of the block. If VAL does not match a unique
1990 edge, NULL is returned. */
1993 find_taken_edge (basic_block bb, tree val)
1997 stmt = last_stmt (bb);
2000 gcc_assert (is_ctrl_stmt (stmt));
2002 /* If VAL is a predicate of the form N RELOP N, where N is an
2003 SSA_NAME, we can always determine its truth value (except when
2004 doing floating point comparisons that may involve NaNs). */
2006 && TREE_CODE_CLASS (TREE_CODE (val)) == '<'
2007 && TREE_OPERAND (val, 0) == TREE_OPERAND (val, 1)
2008 && TREE_CODE (TREE_OPERAND (val, 0)) == SSA_NAME
2009 && (TREE_CODE (TREE_TYPE (TREE_OPERAND (val, 0))) != REAL_TYPE
2010 || !HONOR_NANS (TYPE_MODE (TREE_TYPE (TREE_OPERAND (val, 0))))))
2012 enum tree_code code = TREE_CODE (val);
2014 if (code == EQ_EXPR || code == LE_EXPR || code == GE_EXPR)
2015 val = boolean_true_node;
2016 else if (code == LT_EXPR || code == GT_EXPR || code == NE_EXPR)
2017 val = boolean_false_node;
2020 /* If VAL is not a constant, we can't determine which edge might
2022 if (val == NULL || !really_constant_p (val))
2025 if (TREE_CODE (stmt) == COND_EXPR)
2026 return find_taken_edge_cond_expr (bb, val);
2028 if (TREE_CODE (stmt) == SWITCH_EXPR)
2029 return find_taken_edge_switch_expr (bb, val);
2035 /* Given a constant value VAL and the entry block BB to a COND_EXPR
2036 statement, determine which of the two edges will be taken out of the
2037 block. Return NULL if either edge may be taken. */
2040 find_taken_edge_cond_expr (basic_block bb, tree val)
2042 edge true_edge, false_edge;
2044 extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
2046 /* If both edges of the branch lead to the same basic block, it doesn't
2047 matter which edge is taken. */
2048 if (true_edge->dest == false_edge->dest)
2051 /* Otherwise, try to determine which branch of the if() will be taken.
2052 If VAL is a constant but it can't be reduced to a 0 or a 1, then
2053 we don't really know which edge will be taken at runtime. This
2054 may happen when comparing addresses (e.g., if (&var1 == 4)). */
2055 if (integer_nonzerop (val))
2057 else if (integer_zerop (val))
2064 /* Given a constant value VAL and the entry block BB to a SWITCH_EXPR
2065 statement, determine which edge will be taken out of the block. Return
2066 NULL if any edge may be taken. */
2069 find_taken_edge_switch_expr (basic_block bb, tree val)
2071 tree switch_expr, taken_case;
2072 basic_block dest_bb;
2075 if (TREE_CODE (val) != INTEGER_CST)
2078 switch_expr = last_stmt (bb);
2079 taken_case = find_case_label_for_value (switch_expr, val);
2080 dest_bb = label_to_block (CASE_LABEL (taken_case));
2082 e = find_edge (bb, dest_bb);
2088 /* Return the CASE_LABEL_EXPR that SWITCH_EXPR will take for VAL.
2089 We can make optimal use here of the fact that the case labels are
2090 sorted: We can do a binary search for a case matching VAL. */
2093 find_case_label_for_value (tree switch_expr, tree val)
2095 tree vec = SWITCH_LABELS (switch_expr);
2096 size_t low, high, n = TREE_VEC_LENGTH (vec);
2097 tree default_case = TREE_VEC_ELT (vec, n - 1);
2099 for (low = -1, high = n - 1; high - low > 1; )
2101 size_t i = (high + low) / 2;
2102 tree t = TREE_VEC_ELT (vec, i);
2105 /* Cache the result of comparing CASE_LOW and val. */
2106 cmp = tree_int_cst_compare (CASE_LOW (t), val);
2113 if (CASE_HIGH (t) == NULL)
2115 /* A singe-valued case label. */
2121 /* A case range. We can only handle integer ranges. */
2122 if (cmp <= 0 && tree_int_cst_compare (CASE_HIGH (t), val) >= 0)
2127 return default_case;
2131 /* If all the PHI nodes in DEST have alternatives for E1 and E2 and
2132 those alternatives are equal in each of the PHI nodes, then return
2133 true, else return false. */
2136 phi_alternatives_equal (basic_block dest, edge e1, edge e2)
2138 tree phi, val1, val2;
2141 for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi))
2143 n1 = phi_arg_from_edge (phi, e1);
2144 n2 = phi_arg_from_edge (phi, e2);
2146 gcc_assert (n1 >= 0);
2147 gcc_assert (n2 >= 0);
2149 val1 = PHI_ARG_DEF (phi, n1);
2150 val2 = PHI_ARG_DEF (phi, n2);
2152 if (!operand_equal_p (val1, val2, 0))
2160 /*---------------------------------------------------------------------------
2162 ---------------------------------------------------------------------------*/
2164 /* Dump tree-specific information of block BB to file OUTF. */
2167 tree_dump_bb (basic_block bb, FILE *outf, int indent)
2169 dump_generic_bb (outf, bb, indent, TDF_VOPS);
2173 /* Dump a basic block on stderr. */
2176 debug_tree_bb (basic_block bb)
2178 dump_bb (bb, stderr, 0);
2182 /* Dump basic block with index N on stderr. */
2185 debug_tree_bb_n (int n)
2187 debug_tree_bb (BASIC_BLOCK (n));
2188 return BASIC_BLOCK (n);
2192 /* Dump the CFG on stderr.
2194 FLAGS are the same used by the tree dumping functions
2195 (see TDF_* in tree.h). */
2198 debug_tree_cfg (int flags)
2200 dump_tree_cfg (stderr, flags);
2204 /* Dump the program showing basic block boundaries on the given FILE.
2206 FLAGS are the same used by the tree dumping functions (see TDF_* in
2210 dump_tree_cfg (FILE *file, int flags)
2212 if (flags & TDF_DETAILS)
2214 const char *funcname
2215 = lang_hooks.decl_printable_name (current_function_decl, 2);
2218 fprintf (file, ";; Function %s\n\n", funcname);
2219 fprintf (file, ";; \n%d basic blocks, %d edges, last basic block %d.\n\n",
2220 n_basic_blocks, n_edges, last_basic_block);
2222 brief_dump_cfg (file);
2223 fprintf (file, "\n");
2226 if (flags & TDF_STATS)
2227 dump_cfg_stats (file);
2229 dump_function_to_file (current_function_decl, file, flags | TDF_BLOCKS);
2233 /* Dump CFG statistics on FILE. */
2236 dump_cfg_stats (FILE *file)
2238 static long max_num_merged_labels = 0;
2239 unsigned long size, total = 0;
2242 const char * const fmt_str = "%-30s%-13s%12s\n";
2243 const char * const fmt_str_1 = "%-30s%13d%11lu%c\n";
2244 const char * const fmt_str_3 = "%-43s%11lu%c\n";
2245 const char *funcname
2246 = lang_hooks.decl_printable_name (current_function_decl, 2);
2249 fprintf (file, "\nCFG Statistics for %s\n\n", funcname);
2251 fprintf (file, "---------------------------------------------------------\n");
2252 fprintf (file, fmt_str, "", " Number of ", "Memory");
2253 fprintf (file, fmt_str, "", " instances ", "used ");
2254 fprintf (file, "---------------------------------------------------------\n");
2256 size = n_basic_blocks * sizeof (struct basic_block_def);
2258 fprintf (file, fmt_str_1, "Basic blocks", n_basic_blocks,
2259 SCALE (size), LABEL (size));
2265 for (e = bb->succ; e; e = e->succ_next)
2268 size = n_edges * sizeof (struct edge_def);
2270 fprintf (file, fmt_str_1, "Edges", n_edges, SCALE (size), LABEL (size));
2272 size = n_basic_blocks * sizeof (struct bb_ann_d);
2274 fprintf (file, fmt_str_1, "Basic block annotations", n_basic_blocks,
2275 SCALE (size), LABEL (size));
2277 fprintf (file, "---------------------------------------------------------\n");
2278 fprintf (file, fmt_str_3, "Total memory used by CFG data", SCALE (total),
2280 fprintf (file, "---------------------------------------------------------\n");
2281 fprintf (file, "\n");
2283 if (cfg_stats.num_merged_labels > max_num_merged_labels)
2284 max_num_merged_labels = cfg_stats.num_merged_labels;
2286 fprintf (file, "Coalesced label blocks: %ld (Max so far: %ld)\n",
2287 cfg_stats.num_merged_labels, max_num_merged_labels);
2289 fprintf (file, "\n");
2293 /* Dump CFG statistics on stderr. Keep extern so that it's always
2294 linked in the final executable. */
2297 debug_cfg_stats (void)
2299 dump_cfg_stats (stderr);
2303 /* Dump the flowgraph to a .vcg FILE. */
2306 tree_cfg2vcg (FILE *file)
2310 const char *funcname
2311 = lang_hooks.decl_printable_name (current_function_decl, 2);
2313 /* Write the file header. */
2314 fprintf (file, "graph: { title: \"%s\"\n", funcname);
2315 fprintf (file, "node: { title: \"ENTRY\" label: \"ENTRY\" }\n");
2316 fprintf (file, "node: { title: \"EXIT\" label: \"EXIT\" }\n");
2318 /* Write blocks and edges. */
2319 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
2321 fprintf (file, "edge: { sourcename: \"ENTRY\" targetname: \"%d\"",
2324 if (e->flags & EDGE_FAKE)
2325 fprintf (file, " linestyle: dotted priority: 10");
2327 fprintf (file, " linestyle: solid priority: 100");
2329 fprintf (file, " }\n");
2335 enum tree_code head_code, end_code;
2336 const char *head_name, *end_name;
2339 tree first = first_stmt (bb);
2340 tree last = last_stmt (bb);
2344 head_code = TREE_CODE (first);
2345 head_name = tree_code_name[head_code];
2346 head_line = get_lineno (first);
2349 head_name = "no-statement";
2353 end_code = TREE_CODE (last);
2354 end_name = tree_code_name[end_code];
2355 end_line = get_lineno (last);
2358 end_name = "no-statement";
2360 fprintf (file, "node: { title: \"%d\" label: \"#%d\\n%s (%d)\\n%s (%d)\"}\n",
2361 bb->index, bb->index, head_name, head_line, end_name,
2364 for (e = bb->succ; e; e = e->succ_next)
2366 if (e->dest == EXIT_BLOCK_PTR)
2367 fprintf (file, "edge: { sourcename: \"%d\" targetname: \"EXIT\"", bb->index);
2369 fprintf (file, "edge: { sourcename: \"%d\" targetname: \"%d\"", bb->index, e->dest->index);
2371 if (e->flags & EDGE_FAKE)
2372 fprintf (file, " priority: 10 linestyle: dotted");
2374 fprintf (file, " priority: 100 linestyle: solid");
2376 fprintf (file, " }\n");
2379 if (bb->next_bb != EXIT_BLOCK_PTR)
2383 fputs ("}\n\n", file);
2388 /*---------------------------------------------------------------------------
2389 Miscellaneous helpers
2390 ---------------------------------------------------------------------------*/
2392 /* Return true if T represents a stmt that always transfers control. */
2395 is_ctrl_stmt (tree t)
2397 return (TREE_CODE (t) == COND_EXPR
2398 || TREE_CODE (t) == SWITCH_EXPR
2399 || TREE_CODE (t) == GOTO_EXPR
2400 || TREE_CODE (t) == RETURN_EXPR
2401 || TREE_CODE (t) == RESX_EXPR);
2405 /* Return true if T is a statement that may alter the flow of control
2406 (e.g., a call to a non-returning function). */
2409 is_ctrl_altering_stmt (tree t)
2414 call = get_call_expr_in (t);
2417 /* A non-pure/const CALL_EXPR alters flow control if the current
2418 function has nonlocal labels. */
2419 if (TREE_SIDE_EFFECTS (call) && current_function_has_nonlocal_label)
2422 /* A CALL_EXPR also alters control flow if it does not return. */
2423 if (call_expr_flags (call) & (ECF_NORETURN | ECF_LONGJMP))
2427 /* If a statement can throw, it alters control flow. */
2428 return tree_can_throw_internal (t);
2432 /* Return true if T is a computed goto. */
2435 computed_goto_p (tree t)
2437 return (TREE_CODE (t) == GOTO_EXPR
2438 && TREE_CODE (GOTO_DESTINATION (t)) != LABEL_DECL);
2442 /* Checks whether EXPR is a simple local goto. */
2445 simple_goto_p (tree expr)
2447 return (TREE_CODE (expr) == GOTO_EXPR
2448 && TREE_CODE (GOTO_DESTINATION (expr)) == LABEL_DECL);
2452 /* Return true if T should start a new basic block. PREV_T is the
2453 statement preceding T. It is used when T is a label or a case label.
2454 Labels should only start a new basic block if their previous statement
2455 wasn't a label. Otherwise, sequence of labels would generate
2456 unnecessary basic blocks that only contain a single label. */
2459 stmt_starts_bb_p (tree t, tree prev_t)
2461 enum tree_code code;
2466 /* LABEL_EXPRs start a new basic block only if the preceding
2467 statement wasn't a label of the same type. This prevents the
2468 creation of consecutive blocks that have nothing but a single
2470 code = TREE_CODE (t);
2471 if (code == LABEL_EXPR)
2473 /* Nonlocal and computed GOTO targets always start a new block. */
2474 if (code == LABEL_EXPR
2475 && (DECL_NONLOCAL (LABEL_EXPR_LABEL (t))
2476 || FORCED_LABEL (LABEL_EXPR_LABEL (t))))
2479 if (prev_t && TREE_CODE (prev_t) == code)
2481 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (prev_t)))
2484 cfg_stats.num_merged_labels++;
2495 /* Return true if T should end a basic block. */
2498 stmt_ends_bb_p (tree t)
2500 return is_ctrl_stmt (t) || is_ctrl_altering_stmt (t);
2504 /* Add gotos that used to be represented implicitly in the CFG. */
2507 disband_implicit_edges (void)
2510 block_stmt_iterator last;
2516 last = bsi_last (bb);
2517 stmt = last_stmt (bb);
2519 if (stmt && TREE_CODE (stmt) == COND_EXPR)
2521 /* Remove superfluous gotos from COND_EXPR branches. Moved
2522 from cfg_remove_useless_stmts here since it violates the
2523 invariants for tree--cfg correspondence and thus fits better
2524 here where we do it anyway. */
2525 for (e = bb->succ; e; e = e->succ_next)
2527 if (e->dest != bb->next_bb)
2530 if (e->flags & EDGE_TRUE_VALUE)
2531 COND_EXPR_THEN (stmt) = build_empty_stmt ();
2532 else if (e->flags & EDGE_FALSE_VALUE)
2533 COND_EXPR_ELSE (stmt) = build_empty_stmt ();
2536 e->flags |= EDGE_FALLTHRU;
2542 if (stmt && TREE_CODE (stmt) == RETURN_EXPR)
2544 /* Remove the RETURN_EXPR if we may fall though to the exit
2546 gcc_assert (bb->succ);
2547 gcc_assert (!bb->succ->succ_next);
2548 gcc_assert (bb->succ->dest == EXIT_BLOCK_PTR);
2550 if (bb->next_bb == EXIT_BLOCK_PTR
2551 && !TREE_OPERAND (stmt, 0))
2554 bb->succ->flags |= EDGE_FALLTHRU;
2559 /* There can be no fallthru edge if the last statement is a control
2561 if (stmt && is_ctrl_stmt (stmt))
2564 /* Find a fallthru edge and emit the goto if necessary. */
2565 for (e = bb->succ; e; e = e->succ_next)
2566 if (e->flags & EDGE_FALLTHRU)
2569 if (!e || e->dest == bb->next_bb)
2572 gcc_assert (e->dest != EXIT_BLOCK_PTR);
2573 label = tree_block_label (e->dest);
2575 stmt = build1 (GOTO_EXPR, void_type_node, label);
2576 #ifdef USE_MAPPED_LOCATION
2577 SET_EXPR_LOCATION (stmt, e->goto_locus);
2579 SET_EXPR_LOCUS (stmt, e->goto_locus);
2581 bsi_insert_after (&last, stmt, BSI_NEW_STMT);
2582 e->flags &= ~EDGE_FALLTHRU;
2586 /* Remove block annotations and other datastructures. */
2589 delete_tree_cfg_annotations (void)
2592 if (n_basic_blocks > 0)
2593 free_blocks_annotations ();
2595 label_to_block_map = NULL;
2602 /* Return the first statement in basic block BB. */
2605 first_stmt (basic_block bb)
2607 block_stmt_iterator i = bsi_start (bb);
2608 return !bsi_end_p (i) ? bsi_stmt (i) : NULL_TREE;
2612 /* Return the last statement in basic block BB. */
2615 last_stmt (basic_block bb)
2617 block_stmt_iterator b = bsi_last (bb);
2618 return !bsi_end_p (b) ? bsi_stmt (b) : NULL_TREE;
2622 /* Return a pointer to the last statement in block BB. */
2625 last_stmt_ptr (basic_block bb)
2627 block_stmt_iterator last = bsi_last (bb);
2628 return !bsi_end_p (last) ? bsi_stmt_ptr (last) : NULL;
2632 /* Return the last statement of an otherwise empty block. Return NULL
2633 if the block is totally empty, or if it contains more than one
2637 last_and_only_stmt (basic_block bb)
2639 block_stmt_iterator i = bsi_last (bb);
2645 last = bsi_stmt (i);
2650 /* Empty statements should no longer appear in the instruction stream.
2651 Everything that might have appeared before should be deleted by
2652 remove_useless_stmts, and the optimizers should just bsi_remove
2653 instead of smashing with build_empty_stmt.
2655 Thus the only thing that should appear here in a block containing
2656 one executable statement is a label. */
2657 prev = bsi_stmt (i);
2658 if (TREE_CODE (prev) == LABEL_EXPR)
2665 /* Mark BB as the basic block holding statement T. */
2668 set_bb_for_stmt (tree t, basic_block bb)
2670 if (TREE_CODE (t) == PHI_NODE)
2672 else if (TREE_CODE (t) == STATEMENT_LIST)
2674 tree_stmt_iterator i;
2675 for (i = tsi_start (t); !tsi_end_p (i); tsi_next (&i))
2676 set_bb_for_stmt (tsi_stmt (i), bb);
2680 stmt_ann_t ann = get_stmt_ann (t);
2683 /* If the statement is a label, add the label to block-to-labels map
2684 so that we can speed up edge creation for GOTO_EXPRs. */
2685 if (TREE_CODE (t) == LABEL_EXPR)
2689 t = LABEL_EXPR_LABEL (t);
2690 uid = LABEL_DECL_UID (t);
2693 LABEL_DECL_UID (t) = uid = cfun->last_label_uid++;
2694 if (VARRAY_SIZE (label_to_block_map) <= (unsigned) uid)
2695 VARRAY_GROW (label_to_block_map, 3 * uid / 2);
2698 /* We're moving an existing label. Make sure that we've
2699 removed it from the old block. */
2700 gcc_assert (!bb || !VARRAY_BB (label_to_block_map, uid));
2701 VARRAY_BB (label_to_block_map, uid) = bb;
2706 /* Finds iterator for STMT. */
2708 extern block_stmt_iterator
2709 stmt_for_bsi (tree stmt)
2711 block_stmt_iterator bsi;
2713 for (bsi = bsi_start (bb_for_stmt (stmt)); !bsi_end_p (bsi); bsi_next (&bsi))
2714 if (bsi_stmt (bsi) == stmt)
2720 /* Insert statement (or statement list) T before the statement
2721 pointed-to by iterator I. M specifies how to update iterator I
2722 after insertion (see enum bsi_iterator_update). */
2725 bsi_insert_before (block_stmt_iterator *i, tree t, enum bsi_iterator_update m)
2727 set_bb_for_stmt (t, i->bb);
2728 tsi_link_before (&i->tsi, t, m);
2733 /* Insert statement (or statement list) T after the statement
2734 pointed-to by iterator I. M specifies how to update iterator I
2735 after insertion (see enum bsi_iterator_update). */
2738 bsi_insert_after (block_stmt_iterator *i, tree t, enum bsi_iterator_update m)
2740 set_bb_for_stmt (t, i->bb);
2741 tsi_link_after (&i->tsi, t, m);
2746 /* Remove the statement pointed to by iterator I. The iterator is updated
2747 to the next statement. */
2750 bsi_remove (block_stmt_iterator *i)
2752 tree t = bsi_stmt (*i);
2753 set_bb_for_stmt (t, NULL);
2754 tsi_delink (&i->tsi);
2758 /* Move the statement at FROM so it comes right after the statement at TO. */
2761 bsi_move_after (block_stmt_iterator *from, block_stmt_iterator *to)
2763 tree stmt = bsi_stmt (*from);
2765 bsi_insert_after (to, stmt, BSI_SAME_STMT);
2769 /* Move the statement at FROM so it comes right before the statement at TO. */
2772 bsi_move_before (block_stmt_iterator *from, block_stmt_iterator *to)
2774 tree stmt = bsi_stmt (*from);
2776 bsi_insert_before (to, stmt, BSI_SAME_STMT);
2780 /* Move the statement at FROM to the end of basic block BB. */
2783 bsi_move_to_bb_end (block_stmt_iterator *from, basic_block bb)
2785 block_stmt_iterator last = bsi_last (bb);
2787 /* Have to check bsi_end_p because it could be an empty block. */
2788 if (!bsi_end_p (last) && is_ctrl_stmt (bsi_stmt (last)))
2789 bsi_move_before (from, &last);
2791 bsi_move_after (from, &last);
2795 /* Replace the contents of the statement pointed to by iterator BSI
2796 with STMT. If PRESERVE_EH_INFO is true, the exception handling
2797 information of the original statement is preserved. */
2800 bsi_replace (const block_stmt_iterator *bsi, tree stmt, bool preserve_eh_info)
2803 tree orig_stmt = bsi_stmt (*bsi);
2805 SET_EXPR_LOCUS (stmt, EXPR_LOCUS (orig_stmt));
2806 set_bb_for_stmt (stmt, bsi->bb);
2808 /* Preserve EH region information from the original statement, if
2809 requested by the caller. */
2810 if (preserve_eh_info)
2812 eh_region = lookup_stmt_eh_region (orig_stmt);
2814 add_stmt_to_eh_region (stmt, eh_region);
2817 *bsi_stmt_ptr (*bsi) = stmt;
2822 /* Insert the statement pointed-to by BSI into edge E. Every attempt
2823 is made to place the statement in an existing basic block, but
2824 sometimes that isn't possible. When it isn't possible, the edge is
2825 split and the statement is added to the new block.
2827 In all cases, the returned *BSI points to the correct location. The
2828 return value is true if insertion should be done after the location,
2829 or false if it should be done before the location. If new basic block
2830 has to be created, it is stored in *NEW_BB. */
2833 tree_find_edge_insert_loc (edge e, block_stmt_iterator *bsi,
2834 basic_block *new_bb)
2836 basic_block dest, src;
2842 /* If the destination has one predecessor which has no PHI nodes,
2843 insert there. Except for the exit block.
2845 The requirement for no PHI nodes could be relaxed. Basically we
2846 would have to examine the PHIs to prove that none of them used
2847 the value set by the statement we want to insert on E. That
2848 hardly seems worth the effort. */
2849 if (dest->pred->pred_next == NULL
2850 && ! phi_nodes (dest)
2851 && dest != EXIT_BLOCK_PTR)
2853 *bsi = bsi_start (dest);
2854 if (bsi_end_p (*bsi))
2857 /* Make sure we insert after any leading labels. */
2858 tmp = bsi_stmt (*bsi);
2859 while (TREE_CODE (tmp) == LABEL_EXPR)
2862 if (bsi_end_p (*bsi))
2864 tmp = bsi_stmt (*bsi);
2867 if (bsi_end_p (*bsi))
2869 *bsi = bsi_last (dest);
2876 /* If the source has one successor, the edge is not abnormal and
2877 the last statement does not end a basic block, insert there.
2878 Except for the entry block. */
2880 if ((e->flags & EDGE_ABNORMAL) == 0
2881 && src->succ->succ_next == NULL
2882 && src != ENTRY_BLOCK_PTR)
2884 *bsi = bsi_last (src);
2885 if (bsi_end_p (*bsi))
2888 tmp = bsi_stmt (*bsi);
2889 if (!stmt_ends_bb_p (tmp))
2892 /* Insert code just before returning the value. We may need to decompose
2893 the return in the case it contains non-trivial operand. */
2894 if (TREE_CODE (tmp) == RETURN_EXPR)
2896 tree op = TREE_OPERAND (tmp, 0);
2897 if (!is_gimple_val (op))
2899 gcc_assert (TREE_CODE (op) == MODIFY_EXPR);
2900 bsi_insert_before (bsi, op, BSI_NEW_STMT);
2901 TREE_OPERAND (tmp, 0) = TREE_OPERAND (op, 0);
2908 /* Otherwise, create a new basic block, and split this edge. */
2909 dest = split_edge (e);
2917 /* This routine will commit all pending edge insertions, creating any new
2918 basic blocks which are necessary.
2920 If specified, NEW_BLOCKS returns a count of the number of new basic
2921 blocks which were created. */
2924 bsi_commit_edge_inserts (int *new_blocks)
2930 blocks = n_basic_blocks;
2932 bsi_commit_edge_inserts_1 (ENTRY_BLOCK_PTR->succ);
2935 for (e = bb->succ; e; e = e->succ_next)
2936 bsi_commit_edge_inserts_1 (e);
2939 *new_blocks = n_basic_blocks - blocks;
2943 /* Commit insertions pending at edge E. */
2946 bsi_commit_edge_inserts_1 (edge e)
2948 if (PENDING_STMT (e))
2950 block_stmt_iterator bsi;
2951 tree stmt = PENDING_STMT (e);
2953 PENDING_STMT (e) = NULL_TREE;
2955 if (tree_find_edge_insert_loc (e, &bsi, NULL))
2956 bsi_insert_after (&bsi, stmt, BSI_NEW_STMT);
2958 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
2963 /* Add STMT to the pending list of edge E. No actual insertion is
2964 made until a call to bsi_commit_edge_inserts () is made. */
2967 bsi_insert_on_edge (edge e, tree stmt)
2969 append_to_statement_list (stmt, &PENDING_STMT (e));
2972 /* Similar to bsi_insert_on_edge+bsi_commit_edge_inserts. If new block has to
2973 be created, it is returned. */
2976 bsi_insert_on_edge_immediate (edge e, tree stmt)
2978 block_stmt_iterator bsi;
2979 basic_block new_bb = NULL;
2981 gcc_assert (!PENDING_STMT (e));
2983 if (tree_find_edge_insert_loc (e, &bsi, &new_bb))
2984 bsi_insert_after (&bsi, stmt, BSI_NEW_STMT);
2986 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
2991 /*---------------------------------------------------------------------------
2992 Tree specific functions for CFG manipulation
2993 ---------------------------------------------------------------------------*/
2995 /* Split a (typically critical) edge EDGE_IN. Return the new block.
2996 Abort on abnormal edges. */
2999 tree_split_edge (edge edge_in)
3001 basic_block new_bb, after_bb, dest, src;
3006 /* Abnormal edges cannot be split. */
3007 gcc_assert (!(edge_in->flags & EDGE_ABNORMAL));
3010 dest = edge_in->dest;
3012 /* Place the new block in the block list. Try to keep the new block
3013 near its "logical" location. This is of most help to humans looking
3014 at debugging dumps. */
3015 for (e = dest->pred; e; e = e->pred_next)
3016 if (e->src->next_bb == dest)
3019 after_bb = dest->prev_bb;
3021 after_bb = edge_in->src;
3023 new_bb = create_empty_bb (after_bb);
3024 new_bb->frequency = EDGE_FREQUENCY (edge_in);
3025 new_bb->count = edge_in->count;
3026 new_edge = make_edge (new_bb, dest, EDGE_FALLTHRU);
3027 new_edge->probability = REG_BR_PROB_BASE;
3028 new_edge->count = edge_in->count;
3030 /* Find all the PHI arguments on the original edge, and change them to
3031 the new edge. Do it before redirection, so that the argument does not
3033 for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi))
3035 num_elem = PHI_NUM_ARGS (phi);
3036 for (i = 0; i < num_elem; i++)
3037 if (PHI_ARG_EDGE (phi, i) == edge_in)
3039 PHI_ARG_EDGE (phi, i) = new_edge;
3044 e = redirect_edge_and_branch (edge_in, new_bb);
3046 gcc_assert (!PENDING_STMT (edge_in));
3052 /* Return true when BB has label LABEL in it. */
3055 has_label_p (basic_block bb, tree label)
3057 block_stmt_iterator bsi;
3059 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3061 tree stmt = bsi_stmt (bsi);
3063 if (TREE_CODE (stmt) != LABEL_EXPR)
3065 if (LABEL_EXPR_LABEL (stmt) == label)
3072 /* Callback for walk_tree, check that all elements with address taken are
3073 properly noticed as such. */
3076 verify_expr (tree *tp, int *walk_subtrees, void *data ATTRIBUTE_UNUSED)
3083 /* Check operand N for being valid GIMPLE and give error MSG if not.
3084 We check for constants explicitly since they are not considered
3085 gimple invariants if they overflowed. */
3086 #define CHECK_OP(N, MSG) \
3087 do { if (TREE_CODE_CLASS (TREE_CODE (TREE_OPERAND (t, N))) != 'c' \
3088 && !is_gimple_val (TREE_OPERAND (t, N))) \
3089 { error (MSG); return TREE_OPERAND (t, N); }} while (0)
3091 switch (TREE_CODE (t))
3094 if (SSA_NAME_IN_FREE_LIST (t))
3096 error ("SSA name in freelist but still referenced");
3102 x = TREE_OPERAND (t, 0);
3103 if (TREE_CODE (x) == BIT_FIELD_REF
3104 && is_gimple_reg (TREE_OPERAND (x, 0)))
3106 error ("GIMPLE register modified with BIT_FIELD_REF");
3112 /* Skip any references (they will be checked when we recurse down the
3113 tree) and ensure that any variable used as a prefix is marked
3115 for (x = TREE_OPERAND (t, 0);
3116 (handled_component_p (x)
3117 || TREE_CODE (x) == REALPART_EXPR
3118 || TREE_CODE (x) == IMAGPART_EXPR);
3119 x = TREE_OPERAND (x, 0))
3122 if (TREE_CODE (x) != VAR_DECL && TREE_CODE (x) != PARM_DECL)
3124 if (!TREE_ADDRESSABLE (x))
3126 error ("address taken, but ADDRESSABLE bit not set");
3132 x = TREE_OPERAND (t, 0);
3133 if (TREE_CODE (TREE_TYPE (x)) != BOOLEAN_TYPE)
3135 error ("non-boolean used in condition");
3142 case FIX_TRUNC_EXPR:
3144 case FIX_FLOOR_EXPR:
3145 case FIX_ROUND_EXPR:
3150 case NON_LVALUE_EXPR:
3151 case TRUTH_NOT_EXPR:
3152 CHECK_OP (0, "Invalid operand to unary operator");
3159 case ARRAY_RANGE_REF:
3161 case VIEW_CONVERT_EXPR:
3162 /* We have a nest of references. Verify that each of the operands
3163 that determine where to reference is either a constant or a variable,
3164 verify that the base is valid, and then show we've already checked
3166 while (TREE_CODE (t) == REALPART_EXPR || TREE_CODE (t) == IMAGPART_EXPR
3167 || handled_component_p (t))
3169 if (TREE_CODE (t) == COMPONENT_REF && TREE_OPERAND (t, 2))
3170 CHECK_OP (2, "Invalid COMPONENT_REF offset operator");
3171 else if (TREE_CODE (t) == ARRAY_REF
3172 || TREE_CODE (t) == ARRAY_RANGE_REF)
3174 CHECK_OP (1, "Invalid array index.");
3175 if (TREE_OPERAND (t, 2))
3176 CHECK_OP (2, "Invalid array lower bound.");
3177 if (TREE_OPERAND (t, 3))
3178 CHECK_OP (3, "Invalid array stride.");
3180 else if (TREE_CODE (t) == BIT_FIELD_REF)
3182 CHECK_OP (1, "Invalid operand to BIT_FIELD_REF");
3183 CHECK_OP (2, "Invalid operand to BIT_FIELD_REF");
3186 t = TREE_OPERAND (t, 0);
3189 if (TREE_CODE_CLASS (TREE_CODE (t)) != 'c'
3190 && !is_gimple_lvalue (t))
3192 error ("Invalid reference prefix.");
3204 case UNORDERED_EXPR:
3215 case TRUNC_DIV_EXPR:
3217 case FLOOR_DIV_EXPR:
3218 case ROUND_DIV_EXPR:
3219 case TRUNC_MOD_EXPR:
3221 case FLOOR_MOD_EXPR:
3222 case ROUND_MOD_EXPR:
3224 case EXACT_DIV_EXPR:
3234 CHECK_OP (0, "Invalid operand to binary operator");
3235 CHECK_OP (1, "Invalid operand to binary operator");
3247 /* Verify STMT, return true if STMT is not in GIMPLE form.
3248 TODO: Implement type checking. */
3251 verify_stmt (tree stmt, bool last_in_block)
3255 if (!is_gimple_stmt (stmt))
3257 error ("Is not a valid GIMPLE statement.");
3261 addr = walk_tree (&stmt, verify_expr, NULL, NULL);
3264 debug_generic_stmt (addr);
3268 /* If the statement is marked as part of an EH region, then it is
3269 expected that the statement could throw. Verify that when we
3270 have optimizations that simplify statements such that we prove
3271 that they cannot throw, that we update other data structures
3273 if (lookup_stmt_eh_region (stmt) >= 0)
3275 if (!tree_could_throw_p (stmt))
3277 error ("Statement marked for throw, but doesn't.");
3280 if (!last_in_block && tree_can_throw_internal (stmt))
3282 error ("Statement marked for throw in middle of block.");
3290 debug_generic_stmt (stmt);
3295 /* Return true when the T can be shared. */
3298 tree_node_can_be_shared (tree t)
3300 if (TYPE_P (t) || DECL_P (t)
3301 /* We check for constants explicitly since they are not considered
3302 gimple invariants if they overflowed. */
3303 || TREE_CODE_CLASS (TREE_CODE (t)) == 'c'
3304 || is_gimple_min_invariant (t)
3305 || TREE_CODE (t) == SSA_NAME)
3308 while (((TREE_CODE (t) == ARRAY_REF || TREE_CODE (t) == ARRAY_RANGE_REF)
3309 /* We check for constants explicitly since they are not considered
3310 gimple invariants if they overflowed. */
3311 && (TREE_CODE_CLASS (TREE_CODE (TREE_OPERAND (t, 1))) == 'c'
3312 || is_gimple_min_invariant (TREE_OPERAND (t, 1))))
3313 || (TREE_CODE (t) == COMPONENT_REF
3314 || TREE_CODE (t) == REALPART_EXPR
3315 || TREE_CODE (t) == IMAGPART_EXPR))
3316 t = TREE_OPERAND (t, 0);
3325 /* Called via walk_trees. Verify tree sharing. */
3328 verify_node_sharing (tree * tp, int *walk_subtrees, void *data)
3330 htab_t htab = (htab_t) data;
3333 if (tree_node_can_be_shared (*tp))
3335 *walk_subtrees = false;
3339 slot = htab_find_slot (htab, *tp, INSERT);
3348 /* Verify the GIMPLE statement chain. */
3354 block_stmt_iterator bsi;
3359 timevar_push (TV_TREE_STMT_VERIFY);
3360 htab = htab_create (37, htab_hash_pointer, htab_eq_pointer, NULL);
3367 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
3369 int phi_num_args = PHI_NUM_ARGS (phi);
3371 for (i = 0; i < phi_num_args; i++)
3373 tree t = PHI_ARG_DEF (phi, i);
3376 /* Addressable variables do have SSA_NAMEs but they
3377 are not considered gimple values. */
3378 if (TREE_CODE (t) != SSA_NAME
3379 && TREE_CODE (t) != FUNCTION_DECL
3380 && !is_gimple_val (t))
3382 error ("PHI def is not a GIMPLE value");
3383 debug_generic_stmt (phi);
3384 debug_generic_stmt (t);
3388 addr = walk_tree (&t, verify_expr, NULL, NULL);
3391 debug_generic_stmt (addr);
3395 addr = walk_tree (&t, verify_node_sharing, htab, NULL);
3398 error ("Incorrect sharing of tree nodes");
3399 debug_generic_stmt (phi);
3400 debug_generic_stmt (addr);
3406 for (bsi = bsi_start (bb); !bsi_end_p (bsi); )
3408 tree stmt = bsi_stmt (bsi);
3410 err |= verify_stmt (stmt, bsi_end_p (bsi));
3411 addr = walk_tree (&stmt, verify_node_sharing, htab, NULL);
3414 error ("Incorrect sharing of tree nodes");
3415 debug_generic_stmt (stmt);
3416 debug_generic_stmt (addr);
3423 internal_error ("verify_stmts failed.");
3426 timevar_pop (TV_TREE_STMT_VERIFY);
3430 /* Verifies that the flow information is OK. */
3433 tree_verify_flow_info (void)
3437 block_stmt_iterator bsi;
3441 if (ENTRY_BLOCK_PTR->stmt_list)
3443 error ("ENTRY_BLOCK has a statement list associated with it\n");
3447 if (EXIT_BLOCK_PTR->stmt_list)
3449 error ("EXIT_BLOCK has a statement list associated with it\n");
3453 for (e = EXIT_BLOCK_PTR->pred; e; e = e->pred_next)
3454 if (e->flags & EDGE_FALLTHRU)
3456 error ("Fallthru to exit from bb %d\n", e->src->index);
3462 bool found_ctrl_stmt = false;
3464 /* Skip labels on the start of basic block. */
3465 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3467 if (TREE_CODE (bsi_stmt (bsi)) != LABEL_EXPR)
3470 if (label_to_block (LABEL_EXPR_LABEL (bsi_stmt (bsi))) != bb)
3472 error ("Label %s to block does not match in bb %d\n",
3473 IDENTIFIER_POINTER (DECL_NAME (bsi_stmt (bsi))),
3478 if (decl_function_context (LABEL_EXPR_LABEL (bsi_stmt (bsi)))
3479 != current_function_decl)
3481 error ("Label %s has incorrect context in bb %d\n",
3482 IDENTIFIER_POINTER (DECL_NAME (bsi_stmt (bsi))),
3488 /* Verify that body of basic block BB is free of control flow. */
3489 for (; !bsi_end_p (bsi); bsi_next (&bsi))
3491 tree stmt = bsi_stmt (bsi);
3493 if (found_ctrl_stmt)
3495 error ("Control flow in the middle of basic block %d\n",
3500 if (stmt_ends_bb_p (stmt))
3501 found_ctrl_stmt = true;
3503 if (TREE_CODE (stmt) == LABEL_EXPR)
3505 error ("Label %s in the middle of basic block %d\n",
3506 IDENTIFIER_POINTER (DECL_NAME (stmt)),
3511 bsi = bsi_last (bb);
3512 if (bsi_end_p (bsi))
3515 stmt = bsi_stmt (bsi);
3517 if (is_ctrl_stmt (stmt))
3519 for (e = bb->succ; e; e = e->succ_next)
3520 if (e->flags & EDGE_FALLTHRU)
3522 error ("Fallthru edge after a control statement in bb %d \n",
3528 switch (TREE_CODE (stmt))
3534 if (TREE_CODE (COND_EXPR_THEN (stmt)) != GOTO_EXPR
3535 || TREE_CODE (COND_EXPR_ELSE (stmt)) != GOTO_EXPR)
3537 error ("Structured COND_EXPR at the end of bb %d\n", bb->index);
3541 extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
3543 if (!true_edge || !false_edge
3544 || !(true_edge->flags & EDGE_TRUE_VALUE)
3545 || !(false_edge->flags & EDGE_FALSE_VALUE)
3546 || (true_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL))
3547 || (false_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL))
3548 || bb->succ->succ_next->succ_next)
3550 error ("Wrong outgoing edge flags at end of bb %d\n",
3555 if (!has_label_p (true_edge->dest,
3556 GOTO_DESTINATION (COND_EXPR_THEN (stmt))))
3558 error ("`then' label does not match edge at end of bb %d\n",
3563 if (!has_label_p (false_edge->dest,
3564 GOTO_DESTINATION (COND_EXPR_ELSE (stmt))))
3566 error ("`else' label does not match edge at end of bb %d\n",
3574 if (simple_goto_p (stmt))
3576 error ("Explicit goto at end of bb %d\n", bb->index);
3581 /* FIXME. We should double check that the labels in the
3582 destination blocks have their address taken. */
3583 for (e = bb->succ; e; e = e->succ_next)
3584 if ((e->flags & (EDGE_FALLTHRU | EDGE_TRUE_VALUE
3585 | EDGE_FALSE_VALUE))
3586 || !(e->flags & EDGE_ABNORMAL))
3588 error ("Wrong outgoing edge flags at end of bb %d\n",
3596 if (!bb->succ || bb->succ->succ_next
3597 || (bb->succ->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL
3598 | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
3600 error ("Wrong outgoing edge flags at end of bb %d\n", bb->index);
3603 if (bb->succ->dest != EXIT_BLOCK_PTR)
3605 error ("Return edge does not point to exit in bb %d\n",
3618 vec = SWITCH_LABELS (stmt);
3619 n = TREE_VEC_LENGTH (vec);
3621 /* Mark all the destination basic blocks. */
3622 for (i = 0; i < n; ++i)
3624 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
3625 basic_block label_bb = label_to_block (lab);
3627 gcc_assert (!label_bb->aux || label_bb->aux == (void *)1);
3628 label_bb->aux = (void *)1;
3631 /* Verify that the case labels are sorted. */
3632 prev = TREE_VEC_ELT (vec, 0);
3633 for (i = 1; i < n - 1; ++i)
3635 tree c = TREE_VEC_ELT (vec, i);
3638 error ("Found default case not at end of case vector");
3642 if (! tree_int_cst_lt (CASE_LOW (prev), CASE_LOW (c)))
3644 error ("Case labels not sorted:\n ");
3645 print_generic_expr (stderr, prev, 0);
3646 fprintf (stderr," is greater than ");
3647 print_generic_expr (stderr, c, 0);
3648 fprintf (stderr," but comes before it.\n");
3653 if (CASE_LOW (TREE_VEC_ELT (vec, n - 1)))
3655 error ("No default case found at end of case vector");
3659 for (e = bb->succ; e; e = e->succ_next)
3663 error ("Extra outgoing edge %d->%d\n",
3664 bb->index, e->dest->index);
3667 e->dest->aux = (void *)2;
3668 if ((e->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL
3669 | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
3671 error ("Wrong outgoing edge flags at end of bb %d\n",
3677 /* Check that we have all of them. */
3678 for (i = 0; i < n; ++i)
3680 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
3681 basic_block label_bb = label_to_block (lab);
3683 if (label_bb->aux != (void *)2)
3685 error ("Missing edge %i->%i\n",
3686 bb->index, label_bb->index);
3691 for (e = bb->succ; e; e = e->succ_next)
3692 e->dest->aux = (void *)0;
3699 if (dom_computed[CDI_DOMINATORS] >= DOM_NO_FAST_QUERY)
3700 verify_dominators (CDI_DOMINATORS);
3706 /* Updates phi nodes after creating forwarder block joined
3707 by edge FALLTHRU. */
3710 tree_make_forwarder_block (edge fallthru)
3713 basic_block dummy, bb;
3714 tree phi, new_phi, var, prev, next;
3716 dummy = fallthru->src;
3717 bb = fallthru->dest;
3719 if (!bb->pred->pred_next)
3722 /* If we redirected a branch we must create new phi nodes at the
3724 for (phi = phi_nodes (dummy); phi; phi = PHI_CHAIN (phi))
3726 var = PHI_RESULT (phi);
3727 new_phi = create_phi_node (var, bb);
3728 SSA_NAME_DEF_STMT (var) = new_phi;
3729 SET_PHI_RESULT (phi, make_ssa_name (SSA_NAME_VAR (var), phi));
3730 add_phi_arg (&new_phi, PHI_RESULT (phi), fallthru);
3733 /* Ensure that the PHI node chain is in the same order. */
3735 for (phi = phi_nodes (bb); phi; phi = next)
3737 next = PHI_CHAIN (phi);
3738 PHI_CHAIN (phi) = prev;
3741 set_phi_nodes (bb, prev);
3743 /* Add the arguments we have stored on edges. */
3744 for (e = bb->pred; e; e = e->pred_next)
3749 for (phi = phi_nodes (bb), var = PENDING_STMT (e);
3751 phi = PHI_CHAIN (phi), var = TREE_CHAIN (var))
3752 add_phi_arg (&phi, TREE_VALUE (var), e);
3754 PENDING_STMT (e) = NULL;
3759 /* Return true if basic block BB does nothing except pass control
3760 flow to another block and that we can safely insert a label at
3761 the start of the successor block. */
3764 tree_forwarder_block_p (basic_block bb)
3766 block_stmt_iterator bsi;
3769 /* If we have already determined that this block is not forwardable,
3770 then no further checks are necessary. */
3771 if (! bb_ann (bb)->forwardable)
3774 /* BB must have a single outgoing normal edge. Otherwise it can not be
3775 a forwarder block. */
3777 || bb->succ->succ_next
3778 || bb->succ->dest == EXIT_BLOCK_PTR
3779 || (bb->succ->flags & EDGE_ABNORMAL)
3780 || bb == ENTRY_BLOCK_PTR)
3782 bb_ann (bb)->forwardable = 0;
3786 /* Successors of the entry block are not forwarders. */
3787 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
3790 bb_ann (bb)->forwardable = 0;
3794 /* BB can not have any PHI nodes. This could potentially be relaxed
3795 early in compilation if we re-rewrote the variables appearing in
3796 any PHI nodes in forwarder blocks. */
3799 bb_ann (bb)->forwardable = 0;
3803 /* Now walk through the statements. We can ignore labels, anything else
3804 means this is not a forwarder block. */
3805 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3807 tree stmt = bsi_stmt (bsi);
3809 switch (TREE_CODE (stmt))
3812 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)))
3817 bb_ann (bb)->forwardable = 0;
3826 /* Thread jumps over empty statements.
3828 This code should _not_ thread over obviously equivalent conditions
3829 as that requires nontrivial updates to the SSA graph. */
3834 edge e, next, last, old;
3835 basic_block bb, dest, tmp, old_dest, dom;
3838 bool retval = false;
3841 bb_ann (bb)->forwardable = 1;
3843 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb)
3845 /* Don't waste time on unreachable blocks. */
3849 /* Nor on forwarders. */
3850 if (tree_forwarder_block_p (bb))
3853 /* This block is now part of a forwarding path, mark it as not
3854 forwardable so that we can detect loops. This bit will be
3856 bb_ann (bb)->forwardable = 0;
3858 /* Examine each of our block's successors to see if it is
3860 for (e = bb->succ; e; e = next)
3864 next = e->succ_next;
3866 /* If the edge is abnormal or its destination is not
3867 forwardable, then there's nothing to do. */
3868 if ((e->flags & EDGE_ABNORMAL)
3869 || !tree_forwarder_block_p (e->dest))
3873 freq = EDGE_FREQUENCY (e);
3875 /* Now walk through as many forwarder block as possible to
3876 find the ultimate destination we want to thread our jump
3878 last = e->dest->succ;
3879 bb_ann (e->dest)->forwardable = 0;
3880 for (dest = e->dest->succ->dest;
3881 tree_forwarder_block_p (dest);
3883 dest = dest->succ->dest)
3885 /* An infinite loop detected. We redirect the edge anyway, so
3886 that the loop is shrunk into single basic block. */
3887 if (!bb_ann (dest)->forwardable)
3890 if (dest->succ->dest == EXIT_BLOCK_PTR)
3893 bb_ann (dest)->forwardable = 0;
3894 dest->frequency -= freq;
3895 if (dest->frequency < 0)
3896 dest->frequency = 0;
3897 dest->count -= count;
3898 if (dest->count < 0)
3900 dest->succ->count -= count;
3901 if (dest->succ->count < 0)
3902 dest->succ->count = 0;
3905 /* Reset the forwardable marks to 1. */
3908 tmp = tmp->succ->dest)
3909 bb_ann (tmp)->forwardable = 1;
3911 if (dest == e->dest)
3914 old = find_edge (bb, dest);
3917 /* If there already is an edge, check whether the values
3918 in phi nodes differ. */
3919 if (!phi_alternatives_equal (dest, last, old))
3921 /* The previous block is forwarder. Redirect our jump
3922 to that target instead since we know it has no PHI
3923 nodes that will need updating. */
3926 /* That might mean that no forwarding at all is possible. */
3927 if (dest == e->dest)
3930 old = find_edge (bb, dest);
3934 /* Perform the redirection. */
3937 e = redirect_edge_and_branch (e, dest);
3941 /* Update PHI nodes. We know that the new argument should
3942 have the same value as the argument associated with LAST.
3943 Otherwise we would have changed our target block above. */
3944 for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi))
3946 arg = phi_arg_from_edge (phi, last);
3947 gcc_assert (arg >= 0);
3948 add_phi_arg (&phi, PHI_ARG_DEF (phi, arg), e);
3952 /* Update the dominators. */
3953 if (dom_computed[CDI_DOMINATORS] >= DOM_CONS_OK)
3955 /* Remove the unreachable blocks (observe that if all blocks
3956 were reachable before, only those in the path we threaded
3957 over and did not have any predecessor outside of the path
3958 become unreachable). */
3959 for (; old_dest != dest; old_dest = tmp)
3961 tmp = old_dest->succ->dest;
3966 delete_basic_block (old_dest);
3968 /* If the dominator of the destination was in the path, set its
3969 dominator to the start of the redirected edge. */
3970 if (get_immediate_dominator (CDI_DOMINATORS, old_dest) == NULL)
3971 set_immediate_dominator (CDI_DOMINATORS, old_dest, bb);
3973 /* Now proceed like if we forwarded just over one edge at a time.
3974 Algorithm for forwarding edge S --> A over edge A --> B then
3978 && !dominated_by (S, B))
3979 idom (B) = idom (A);
3980 recount_idom (A); */
3982 for (; old_dest != dest; old_dest = tmp)
3984 tmp = old_dest->succ->dest;
3986 if (get_immediate_dominator (CDI_DOMINATORS, tmp) == old_dest
3987 && !dominated_by_p (CDI_DOMINATORS, bb, tmp))
3989 dom = get_immediate_dominator (CDI_DOMINATORS, old_dest);
3990 set_immediate_dominator (CDI_DOMINATORS, tmp, dom);
3993 dom = recount_dominator (CDI_DOMINATORS, old_dest);
3994 set_immediate_dominator (CDI_DOMINATORS, old_dest, dom);
3999 /* Reset the forwardable bit on our block since it's no longer in
4000 a forwarding chain path. */
4001 bb_ann (bb)->forwardable = 1;
4008 /* Return a non-special label in the head of basic block BLOCK.
4009 Create one if it doesn't exist. */
4012 tree_block_label (basic_block bb)
4014 block_stmt_iterator i, s = bsi_start (bb);
4018 for (i = s; !bsi_end_p (i); first = false, bsi_next (&i))
4020 stmt = bsi_stmt (i);
4021 if (TREE_CODE (stmt) != LABEL_EXPR)
4023 label = LABEL_EXPR_LABEL (stmt);
4024 if (!DECL_NONLOCAL (label))
4027 bsi_move_before (&i, &s);
4032 label = create_artificial_label ();
4033 stmt = build1 (LABEL_EXPR, void_type_node, label);
4034 bsi_insert_before (&s, stmt, BSI_NEW_STMT);
4039 /* Attempt to perform edge redirection by replacing a possibly complex
4040 jump instruction by a goto or by removing the jump completely.
4041 This can apply only if all edges now point to the same block. The
4042 parameters and return values are equivalent to
4043 redirect_edge_and_branch. */
4046 tree_try_redirect_by_replacing_jump (edge e, basic_block target)
4048 basic_block src = e->src;
4050 block_stmt_iterator b;
4053 /* Verify that all targets will be TARGET. */
4054 for (tmp = src->succ; tmp; tmp = tmp->succ_next)
4055 if (tmp->dest != target && tmp != e)
4064 stmt = bsi_stmt (b);
4066 if (TREE_CODE (stmt) == COND_EXPR
4067 || TREE_CODE (stmt) == SWITCH_EXPR)
4070 e = ssa_redirect_edge (e, target);
4071 e->flags = EDGE_FALLTHRU;
4079 /* Redirect E to DEST. Return NULL on failure. Otherwise, return the
4080 edge representing the redirected branch. */
4083 tree_redirect_edge_and_branch (edge e, basic_block dest)
4085 basic_block bb = e->src;
4086 block_stmt_iterator bsi;
4090 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
4093 if (e->src != ENTRY_BLOCK_PTR
4094 && (ret = tree_try_redirect_by_replacing_jump (e, dest)))
4097 if (e->dest == dest)
4100 label = tree_block_label (dest);
4102 bsi = bsi_last (bb);
4103 stmt = bsi_end_p (bsi) ? NULL : bsi_stmt (bsi);
4105 switch (stmt ? TREE_CODE (stmt) : ERROR_MARK)
4108 stmt = (e->flags & EDGE_TRUE_VALUE
4109 ? COND_EXPR_THEN (stmt)
4110 : COND_EXPR_ELSE (stmt));
4111 GOTO_DESTINATION (stmt) = label;
4115 /* No non-abnormal edges should lead from a non-simple goto, and
4116 simple ones should be represented implicitly. */
4121 tree vec = SWITCH_LABELS (stmt);
4122 size_t i, n = TREE_VEC_LENGTH (vec);
4124 for (i = 0; i < n; ++i)
4126 tree elt = TREE_VEC_ELT (vec, i);
4127 if (label_to_block (CASE_LABEL (elt)) == e->dest)
4128 CASE_LABEL (elt) = label;
4135 e->flags |= EDGE_FALLTHRU;
4139 /* Otherwise it must be a fallthru edge, and we don't need to
4140 do anything besides redirecting it. */
4141 gcc_assert (e->flags & EDGE_FALLTHRU);
4145 /* Update/insert PHI nodes as necessary. */
4147 /* Now update the edges in the CFG. */
4148 e = ssa_redirect_edge (e, dest);
4154 /* Simple wrapper, as we can always redirect fallthru edges. */
4157 tree_redirect_edge_and_branch_force (edge e, basic_block dest)
4159 e = tree_redirect_edge_and_branch (e, dest);
4166 /* Splits basic block BB after statement STMT (but at least after the
4167 labels). If STMT is NULL, BB is split just after the labels. */
4170 tree_split_block (basic_block bb, void *stmt)
4172 block_stmt_iterator bsi, bsi_tgt;
4177 new_bb = create_empty_bb (bb);
4179 /* Redirect the outgoing edges. */
4180 new_bb->succ = bb->succ;
4182 for (e = new_bb->succ; e; e = e->succ_next)
4185 if (stmt && TREE_CODE ((tree) stmt) == LABEL_EXPR)
4188 /* Move everything from BSI to the new basic block. */
4189 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4191 act = bsi_stmt (bsi);
4192 if (TREE_CODE (act) == LABEL_EXPR)
4205 bsi_tgt = bsi_start (new_bb);
4206 while (!bsi_end_p (bsi))
4208 act = bsi_stmt (bsi);
4210 bsi_insert_after (&bsi_tgt, act, BSI_NEW_STMT);
4217 /* Moves basic block BB after block AFTER. */
4220 tree_move_block_after (basic_block bb, basic_block after)
4222 if (bb->prev_bb == after)
4226 link_block (bb, after);
4232 /* Return true if basic_block can be duplicated. */
4235 tree_can_duplicate_bb_p (basic_block bb ATTRIBUTE_UNUSED)
4241 /* Create a duplicate of the basic block BB. NOTE: This does not
4242 preserve SSA form. */
4245 tree_duplicate_bb (basic_block bb)
4248 block_stmt_iterator bsi, bsi_tgt;
4250 ssa_op_iter op_iter;
4252 new_bb = create_empty_bb (EXIT_BLOCK_PTR->prev_bb);
4254 for (phi = phi_nodes (bb); phi; phi = TREE_CHAIN (phi))
4256 mark_for_rewrite (PHI_RESULT (phi));
4259 bsi_tgt = bsi_start (new_bb);
4260 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4262 tree stmt = bsi_stmt (bsi);
4265 if (TREE_CODE (stmt) == LABEL_EXPR)
4268 /* Record the definitions. */
4269 get_stmt_operands (stmt);
4271 FOR_EACH_SSA_TREE_OPERAND (val, stmt, op_iter, SSA_OP_ALL_DEFS)
4272 mark_for_rewrite (val);
4274 copy = unshare_expr (stmt);
4276 /* Copy also the virtual operands. */
4277 get_stmt_ann (copy);
4278 copy_virtual_operands (copy, stmt);
4280 bsi_insert_after (&bsi_tgt, copy, BSI_NEW_STMT);
4287 /* Dump FUNCTION_DECL FN to file FILE using FLAGS (see TDF_* in tree.h) */
4290 dump_function_to_file (tree fn, FILE *file, int flags)
4292 tree arg, vars, var;
4293 bool ignore_topmost_bind = false, any_var = false;
4297 fprintf (file, "%s (", lang_hooks.decl_printable_name (fn, 2));
4299 arg = DECL_ARGUMENTS (fn);
4302 print_generic_expr (file, arg, dump_flags);
4303 if (TREE_CHAIN (arg))
4304 fprintf (file, ", ");
4305 arg = TREE_CHAIN (arg);
4307 fprintf (file, ")\n");
4309 if (flags & TDF_RAW)
4311 dump_node (fn, TDF_SLIM | flags, file);
4315 /* When GIMPLE is lowered, the variables are no longer available in
4316 BIND_EXPRs, so display them separately. */
4317 if (cfun && cfun->unexpanded_var_list)
4319 ignore_topmost_bind = true;
4321 fprintf (file, "{\n");
4322 for (vars = cfun->unexpanded_var_list; vars; vars = TREE_CHAIN (vars))
4324 var = TREE_VALUE (vars);
4326 print_generic_decl (file, var, flags);
4327 fprintf (file, "\n");
4333 if (basic_block_info)
4335 /* Make a CFG based dump. */
4336 check_bb_profile (ENTRY_BLOCK_PTR, file);
4337 if (!ignore_topmost_bind)
4338 fprintf (file, "{\n");
4340 if (any_var && n_basic_blocks)
4341 fprintf (file, "\n");
4344 dump_generic_bb (file, bb, 2, flags);
4346 fprintf (file, "}\n");
4347 check_bb_profile (EXIT_BLOCK_PTR, file);
4353 /* Make a tree based dump. */
4354 chain = DECL_SAVED_TREE (fn);
4356 if (TREE_CODE (chain) == BIND_EXPR)
4358 if (ignore_topmost_bind)
4360 chain = BIND_EXPR_BODY (chain);
4368 if (!ignore_topmost_bind)
4369 fprintf (file, "{\n");
4374 fprintf (file, "\n");
4376 print_generic_stmt_indented (file, chain, flags, indent);
4377 if (ignore_topmost_bind)
4378 fprintf (file, "}\n");
4381 fprintf (file, "\n\n");
4385 /* Pretty print of the loops intermediate representation. */
4386 static void print_loop (FILE *, struct loop *, int);
4387 static void print_pred_bbs (FILE *, edge);
4388 static void print_succ_bbs (FILE *, edge);
4391 /* Print the predecessors indexes of edge E on FILE. */
4394 print_pred_bbs (FILE *file, edge e)
4399 else if (e->pred_next == NULL)
4400 fprintf (file, "bb_%d", e->src->index);
4404 fprintf (file, "bb_%d, ", e->src->index);
4405 print_pred_bbs (file, e->pred_next);
4410 /* Print the successors indexes of edge E on FILE. */
4413 print_succ_bbs (FILE *file, edge e)
4417 else if (e->succ_next == NULL)
4418 fprintf (file, "bb_%d", e->dest->index);
4421 fprintf (file, "bb_%d, ", e->dest->index);
4422 print_succ_bbs (file, e->succ_next);
4427 /* Pretty print LOOP on FILE, indented INDENT spaces. */
4430 print_loop (FILE *file, struct loop *loop, int indent)
4438 s_indent = (char *) alloca ((size_t) indent + 1);
4439 memset ((void *) s_indent, ' ', (size_t) indent);
4440 s_indent[indent] = '\0';
4442 /* Print the loop's header. */
4443 fprintf (file, "%sloop_%d\n", s_indent, loop->num);
4445 /* Print the loop's body. */
4446 fprintf (file, "%s{\n", s_indent);
4448 if (bb->loop_father == loop)
4450 /* Print the basic_block's header. */
4451 fprintf (file, "%s bb_%d (preds = {", s_indent, bb->index);
4452 print_pred_bbs (file, bb->pred);
4453 fprintf (file, "}, succs = {");
4454 print_succ_bbs (file, bb->succ);
4455 fprintf (file, "})\n");
4457 /* Print the basic_block's body. */
4458 fprintf (file, "%s {\n", s_indent);
4459 tree_dump_bb (bb, file, indent + 4);
4460 fprintf (file, "%s }\n", s_indent);
4463 print_loop (file, loop->inner, indent + 2);
4464 fprintf (file, "%s}\n", s_indent);
4465 print_loop (file, loop->next, indent);
4469 /* Follow a CFG edge from the entry point of the program, and on entry
4470 of a loop, pretty print the loop structure on FILE. */
4473 print_loop_ir (FILE *file)
4477 bb = BASIC_BLOCK (0);
4478 if (bb && bb->loop_father)
4479 print_loop (file, bb->loop_father, 0);
4483 /* Debugging loops structure at tree level. */
4486 debug_loop_ir (void)
4488 print_loop_ir (stderr);
4492 /* Return true if BB ends with a call, possibly followed by some
4493 instructions that must stay with the call. Return false,
4497 tree_block_ends_with_call_p (basic_block bb)
4499 block_stmt_iterator bsi = bsi_last (bb);
4500 return get_call_expr_in (bsi_stmt (bsi)) != NULL;
4504 /* Return true if BB ends with a conditional branch. Return false,
4508 tree_block_ends_with_condjump_p (basic_block bb)
4510 tree stmt = tsi_stmt (bsi_last (bb).tsi);
4511 return (TREE_CODE (stmt) == COND_EXPR);
4515 /* Return true if we need to add fake edge to exit at statement T.
4516 Helper function for tree_flow_call_edges_add. */
4519 need_fake_edge_p (tree t)
4523 /* NORETURN and LONGJMP calls already have an edge to exit.
4524 CONST, PURE and ALWAYS_RETURN calls do not need one.
4525 We don't currently check for CONST and PURE here, although
4526 it would be a good idea, because those attributes are
4527 figured out from the RTL in mark_constant_function, and
4528 the counter incrementation code from -fprofile-arcs
4529 leads to different results from -fbranch-probabilities. */
4530 call = get_call_expr_in (t);
4532 && !(call_expr_flags (call) &
4533 (ECF_NORETURN | ECF_LONGJMP | ECF_ALWAYS_RETURN)))
4536 if (TREE_CODE (t) == ASM_EXPR
4537 && (ASM_VOLATILE_P (t) || ASM_INPUT_P (t)))
4544 /* Add fake edges to the function exit for any non constant and non
4545 noreturn calls, volatile inline assembly in the bitmap of blocks
4546 specified by BLOCKS or to the whole CFG if BLOCKS is zero. Return
4547 the number of blocks that were split.
4549 The goal is to expose cases in which entering a basic block does
4550 not imply that all subsequent instructions must be executed. */
4553 tree_flow_call_edges_add (sbitmap blocks)
4556 int blocks_split = 0;
4557 int last_bb = last_basic_block;
4558 bool check_last_block = false;
4560 if (n_basic_blocks == 0)
4564 check_last_block = true;
4566 check_last_block = TEST_BIT (blocks, EXIT_BLOCK_PTR->prev_bb->index);
4568 /* In the last basic block, before epilogue generation, there will be
4569 a fallthru edge to EXIT. Special care is required if the last insn
4570 of the last basic block is a call because make_edge folds duplicate
4571 edges, which would result in the fallthru edge also being marked
4572 fake, which would result in the fallthru edge being removed by
4573 remove_fake_edges, which would result in an invalid CFG.
4575 Moreover, we can't elide the outgoing fake edge, since the block
4576 profiler needs to take this into account in order to solve the minimal
4577 spanning tree in the case that the call doesn't return.
4579 Handle this by adding a dummy instruction in a new last basic block. */
4580 if (check_last_block)
4582 basic_block bb = EXIT_BLOCK_PTR->prev_bb;
4583 block_stmt_iterator bsi = bsi_last (bb);
4585 if (!bsi_end_p (bsi))
4588 if (need_fake_edge_p (t))
4592 for (e = bb->succ; e; e = e->succ_next)
4593 if (e->dest == EXIT_BLOCK_PTR)
4595 bsi_insert_on_edge (e, build_empty_stmt ());
4596 bsi_commit_edge_inserts ((int *)NULL);
4602 /* Now add fake edges to the function exit for any non constant
4603 calls since there is no way that we can determine if they will
4605 for (i = 0; i < last_bb; i++)
4607 basic_block bb = BASIC_BLOCK (i);
4608 block_stmt_iterator bsi;
4609 tree stmt, last_stmt;
4614 if (blocks && !TEST_BIT (blocks, i))
4617 bsi = bsi_last (bb);
4618 if (!bsi_end_p (bsi))
4620 last_stmt = bsi_stmt (bsi);
4623 stmt = bsi_stmt (bsi);
4624 if (need_fake_edge_p (stmt))
4627 /* The handling above of the final block before the
4628 epilogue should be enough to verify that there is
4629 no edge to the exit block in CFG already.
4630 Calling make_edge in such case would cause us to
4631 mark that edge as fake and remove it later. */
4632 #ifdef ENABLE_CHECKING
4633 if (stmt == last_stmt)
4634 for (e = bb->succ; e; e = e->succ_next)
4635 gcc_assert (e->dest != EXIT_BLOCK_PTR);
4638 /* Note that the following may create a new basic block
4639 and renumber the existing basic blocks. */
4640 if (stmt != last_stmt)
4642 e = split_block (bb, stmt);
4646 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
4650 while (!bsi_end_p (bsi));
4655 verify_flow_info ();
4657 return blocks_split;
4661 tree_purge_dead_eh_edges (basic_block bb)
4663 bool changed = false;
4665 tree stmt = last_stmt (bb);
4667 if (stmt && tree_can_throw_internal (stmt))
4670 for (e = bb->succ; e ; e = next)
4672 next = e->succ_next;
4673 if (e->flags & EDGE_EH)
4675 ssa_remove_edge (e);
4684 tree_purge_all_dead_eh_edges (bitmap blocks)
4686 bool changed = false;
4689 EXECUTE_IF_SET_IN_BITMAP (blocks, 0, i,
4690 { changed |= tree_purge_dead_eh_edges (BASIC_BLOCK (i)); });
4695 struct cfg_hooks tree_cfg_hooks = {
4697 tree_verify_flow_info,
4698 tree_dump_bb, /* dump_bb */
4699 create_bb, /* create_basic_block */
4700 tree_redirect_edge_and_branch,/* redirect_edge_and_branch */
4701 tree_redirect_edge_and_branch_force,/* redirect_edge_and_branch_force */
4702 remove_bb, /* delete_basic_block */
4703 tree_split_block, /* split_block */
4704 tree_move_block_after, /* move_block_after */
4705 tree_can_merge_blocks_p, /* can_merge_blocks_p */
4706 tree_merge_blocks, /* merge_blocks */
4707 tree_predict_edge, /* predict_edge */
4708 tree_predicted_by_p, /* predicted_by_p */
4709 tree_can_duplicate_bb_p, /* can_duplicate_block_p */
4710 tree_duplicate_bb, /* duplicate_block */
4711 tree_split_edge, /* split_edge */
4712 tree_make_forwarder_block, /* make_forward_block */
4713 NULL, /* tidy_fallthru_edge */
4714 tree_block_ends_with_call_p, /* block_ends_with_call_p */
4715 tree_block_ends_with_condjump_p, /* block_ends_with_condjump_p */
4716 tree_flow_call_edges_add /* flow_call_edges_add */
4720 /* Split all critical edges. */
4723 split_critical_edges (void)
4730 for (e = bb->succ; e ; e = e->succ_next)
4731 if (EDGE_CRITICAL_P (e) && !(e->flags & EDGE_ABNORMAL))
4738 struct tree_opt_pass pass_split_crit_edges =
4740 "crited", /* name */
4742 split_critical_edges, /* execute */
4745 0, /* static_pass_number */
4746 TV_TREE_SPLIT_EDGES, /* tv_id */
4747 PROP_cfg, /* properties required */
4748 PROP_no_crit_edges, /* properties_provided */
4749 0, /* properties_destroyed */
4750 0, /* todo_flags_start */
4751 TODO_dump_func, /* todo_flags_finish */
4756 /* Return EXP if it is a valid GIMPLE rvalue, else gimplify it into
4757 a temporary, make sure and register it to be renamed if necessary,
4758 and finally return the temporary. Put the statements to compute
4759 EXP before the current statement in BSI. */
4762 gimplify_val (block_stmt_iterator *bsi, tree type, tree exp)
4764 tree t, new_stmt, orig_stmt;
4766 if (is_gimple_val (exp))
4769 t = make_rename_temp (type, NULL);
4770 new_stmt = build (MODIFY_EXPR, type, t, exp);
4772 orig_stmt = bsi_stmt (*bsi);
4773 SET_EXPR_LOCUS (new_stmt, EXPR_LOCUS (orig_stmt));
4774 TREE_BLOCK (new_stmt) = TREE_BLOCK (orig_stmt);
4776 bsi_insert_before (bsi, new_stmt, BSI_SAME_STMT);
4781 /* Build a ternary operation and gimplify it. Emit code before BSI.
4782 Return the gimple_val holding the result. */
4785 gimplify_build3 (block_stmt_iterator *bsi, enum tree_code code,
4786 tree type, tree a, tree b, tree c)
4790 ret = fold (build3 (code, type, a, b, c));
4793 return gimplify_val (bsi, type, ret);
4796 /* Build a binary operation and gimplify it. Emit code before BSI.
4797 Return the gimple_val holding the result. */
4800 gimplify_build2 (block_stmt_iterator *bsi, enum tree_code code,
4801 tree type, tree a, tree b)
4805 ret = fold (build2 (code, type, a, b));
4808 return gimplify_val (bsi, type, ret);
4811 /* Build a unary operation and gimplify it. Emit code before BSI.
4812 Return the gimple_val holding the result. */
4815 gimplify_build1 (block_stmt_iterator *bsi, enum tree_code code, tree type,
4820 ret = fold (build1 (code, type, a));
4823 return gimplify_val (bsi, type, ret);
4828 /* Emit return warnings. */
4831 execute_warn_function_return (void)
4833 #ifdef USE_MAPPED_LOCATION
4834 source_location location;
4841 if (warn_missing_noreturn
4842 && !TREE_THIS_VOLATILE (cfun->decl)
4843 && EXIT_BLOCK_PTR->pred == NULL
4844 && !lang_hooks.function.missing_noreturn_ok_p (cfun->decl))
4845 warning ("%Jfunction might be possible candidate for attribute `noreturn'",
4848 /* If we have a path to EXIT, then we do return. */
4849 if (TREE_THIS_VOLATILE (cfun->decl)
4850 && EXIT_BLOCK_PTR->pred != NULL)
4852 #ifdef USE_MAPPED_LOCATION
4853 location = UNKNOWN_LOCATION;
4857 for (e = EXIT_BLOCK_PTR->pred; e ; e = e->pred_next)
4859 last = last_stmt (e->src);
4860 if (TREE_CODE (last) == RETURN_EXPR
4861 #ifdef USE_MAPPED_LOCATION
4862 && (location = EXPR_LOCATION (last)) != UNKNOWN_LOCATION)
4864 && (locus = EXPR_LOCUS (last)) != NULL)
4868 #ifdef USE_MAPPED_LOCATION
4869 if (location == UNKNOWN_LOCATION)
4870 location = cfun->function_end_locus;
4871 warning ("%H`noreturn' function does return", &location);
4874 locus = &cfun->function_end_locus;
4875 warning ("%H`noreturn' function does return", locus);
4879 /* If we see "return;" in some basic block, then we do reach the end
4880 without returning a value. */
4881 else if (warn_return_type
4882 && EXIT_BLOCK_PTR->pred != NULL
4883 && !VOID_TYPE_P (TREE_TYPE (TREE_TYPE (cfun->decl))))
4885 for (e = EXIT_BLOCK_PTR->pred; e ; e = e->pred_next)
4887 tree last = last_stmt (e->src);
4888 if (TREE_CODE (last) == RETURN_EXPR
4889 && TREE_OPERAND (last, 0) == NULL)
4891 #ifdef USE_MAPPED_LOCATION
4892 location = EXPR_LOCATION (last);
4893 if (location == UNKNOWN_LOCATION)
4894 location = cfun->function_end_locus;
4895 warning ("%Hcontrol reaches end of non-void function", &location);
4897 locus = EXPR_LOCUS (last);
4899 locus = &cfun->function_end_locus;
4900 warning ("%Hcontrol reaches end of non-void function", locus);
4909 /* Given a basic block B which ends with a conditional and has
4910 precisely two successors, determine which of the edges is taken if
4911 the conditional is true and which is taken if the conditional is
4912 false. Set TRUE_EDGE and FALSE_EDGE appropriately. */
4915 extract_true_false_edges_from_block (basic_block b,
4921 if (e->flags & EDGE_TRUE_VALUE)
4924 *false_edge = e->succ_next;
4929 *true_edge = e->succ_next;
4933 struct tree_opt_pass pass_warn_function_return =
4937 execute_warn_function_return, /* execute */
4940 0, /* static_pass_number */
4942 PROP_cfg, /* properties_required */
4943 0, /* properties_provided */
4944 0, /* properties_destroyed */
4945 0, /* todo_flags_start */
4946 0, /* todo_flags_finish */
4950 #include "gt-tree-cfg.h"