1 /* Control flow functions for trees.
2 Copyright (C) 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
3 Contributed by Diego Novillo <dnovillo@redhat.com>
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 GCC is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to
19 the Free Software Foundation, 59 Temple Place - Suite 330,
20 Boston, MA 02111-1307, USA. */
24 #include "coretypes.h"
29 #include "hard-reg-set.h"
30 #include "basic-block.h"
37 #include "langhooks.h"
38 #include "diagnostic.h"
39 #include "tree-flow.h"
41 #include "tree-dump.h"
42 #include "tree-pass.h"
46 #include "cfglayout.h"
48 /* This file contains functions for building the Control Flow Graph (CFG)
49 for a function tree. */
51 /* Local declarations. */
53 /* Initial capacity for the basic block array. */
54 static const int initial_cfg_capacity = 20;
56 /* Mapping of labels to their associated blocks. This can greatly speed up
57 building of the CFG in code with lots of gotos. */
58 static GTY(()) varray_type label_to_block_map;
63 long num_merged_labels;
66 static struct cfg_stats_d cfg_stats;
68 /* Nonzero if we found a computed goto while building basic blocks. */
69 static bool found_computed_goto;
71 /* Basic blocks and flowgraphs. */
72 static basic_block create_bb (void *, void *, basic_block);
73 static void create_block_annotation (basic_block);
74 static void free_blocks_annotations (void);
75 static void clear_blocks_annotations (void);
76 static void make_blocks (tree);
77 static void factor_computed_gotos (void);
80 static void make_edges (void);
81 static void make_ctrl_stmt_edges (basic_block);
82 static void make_exit_edges (basic_block);
83 static void make_cond_expr_edges (basic_block);
84 static void make_switch_expr_edges (basic_block);
85 static void make_goto_expr_edges (basic_block);
86 static edge tree_redirect_edge_and_branch (edge, basic_block);
87 static edge tree_try_redirect_by_replacing_jump (edge, basic_block);
88 static void split_critical_edges (void);
90 /* Various helpers. */
91 static inline bool stmt_starts_bb_p (tree, tree);
92 static int tree_verify_flow_info (void);
93 static void tree_make_forwarder_block (edge);
94 static bool thread_jumps (void);
95 static bool tree_forwarder_block_p (basic_block);
96 static void 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 it's 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 (EDGE_COUNT (bb->succs) == 0)
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 (EDGE_COUNT (bb->succs) == 0)
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 an undefined label. Emit a label to
610 the 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 && EDGE_COUNT (bb->succs) == 0)
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)
716 timevar_push (TV_TREE_CLEANUP_CFG);
718 retval = cleanup_control_flow ();
719 retval |= delete_unreachable_blocks ();
720 retval |= thread_jumps ();
722 #ifdef ENABLE_CHECKING
725 gcc_assert (!cleanup_control_flow ());
726 gcc_assert (!delete_unreachable_blocks ());
727 gcc_assert (!thread_jumps ());
731 /* Merging the blocks creates no new opportunities for the other
732 optimizations, so do it here. */
737 #ifdef ENABLE_CHECKING
740 timevar_pop (TV_TREE_CLEANUP_CFG);
745 /* Cleanup useless labels in basic blocks. This is something we wish
746 to do early because it allows us to group case labels before creating
747 the edges for the CFG, and it speeds up block statement iterators in
749 We only run this pass once, running it more than once is probably not
752 /* A map from basic block index to the leading label of that block. */
753 static tree *label_for_bb;
755 /* Callback for for_each_eh_region. Helper for cleanup_dead_labels. */
757 update_eh_label (struct eh_region *region)
759 tree old_label = get_eh_region_tree_label (region);
763 basic_block bb = label_to_block (old_label);
765 /* ??? After optimizing, there may be EH regions with labels
766 that have already been removed from the function body, so
767 there is no basic block for them. */
771 new_label = label_for_bb[bb->index];
772 set_eh_region_tree_label (region, new_label);
776 /* Given LABEL return the first label in the same basic block. */
778 main_block_label (tree label)
780 basic_block bb = label_to_block (label);
782 /* label_to_block possibly inserted undefined label into the chain. */
783 if (!label_for_bb[bb->index])
784 label_for_bb[bb->index] = label;
785 return label_for_bb[bb->index];
788 /* Cleanup redundant labels. This is a three-step process:
789 1) Find the leading label for each block.
790 2) Redirect all references to labels to the leading labels.
791 3) Cleanup all useless labels. */
794 cleanup_dead_labels (void)
797 label_for_bb = xcalloc (last_basic_block, sizeof (tree));
799 /* Find a suitable label for each block. We use the first user-defined
800 label if there is one, or otherwise just the first label we see. */
803 block_stmt_iterator i;
805 for (i = bsi_start (bb); !bsi_end_p (i); bsi_next (&i))
807 tree label, stmt = bsi_stmt (i);
809 if (TREE_CODE (stmt) != LABEL_EXPR)
812 label = LABEL_EXPR_LABEL (stmt);
814 /* If we have not yet seen a label for the current block,
815 remember this one and see if there are more labels. */
816 if (! label_for_bb[bb->index])
818 label_for_bb[bb->index] = label;
822 /* If we did see a label for the current block already, but it
823 is an artificially created label, replace it if the current
824 label is a user defined label. */
825 if (! DECL_ARTIFICIAL (label)
826 && DECL_ARTIFICIAL (label_for_bb[bb->index]))
828 label_for_bb[bb->index] = label;
834 /* Now redirect all jumps/branches to the selected label.
835 First do so for each block ending in a control statement. */
838 tree stmt = last_stmt (bb);
842 switch (TREE_CODE (stmt))
846 tree true_branch, false_branch;
848 true_branch = COND_EXPR_THEN (stmt);
849 false_branch = COND_EXPR_ELSE (stmt);
851 GOTO_DESTINATION (true_branch)
852 = main_block_label (GOTO_DESTINATION (true_branch));
853 GOTO_DESTINATION (false_branch)
854 = main_block_label (GOTO_DESTINATION (false_branch));
862 tree vec = SWITCH_LABELS (stmt);
863 size_t n = TREE_VEC_LENGTH (vec);
865 /* Replace all destination labels. */
866 for (i = 0; i < n; ++i)
867 CASE_LABEL (TREE_VEC_ELT (vec, i))
868 = main_block_label (CASE_LABEL (TREE_VEC_ELT (vec, i)));
873 /* We have to handle GOTO_EXPRs until they're removed, and we don't
874 remove them until after we've created the CFG edges. */
876 if (! computed_goto_p (stmt))
878 GOTO_DESTINATION (stmt)
879 = main_block_label (GOTO_DESTINATION (stmt));
888 for_each_eh_region (update_eh_label);
890 /* Finally, purge dead labels. All user-defined labels and labels that
891 can be the target of non-local gotos are preserved. */
894 block_stmt_iterator i;
895 tree label_for_this_bb = label_for_bb[bb->index];
897 if (! label_for_this_bb)
900 for (i = bsi_start (bb); !bsi_end_p (i); )
902 tree label, stmt = bsi_stmt (i);
904 if (TREE_CODE (stmt) != LABEL_EXPR)
907 label = LABEL_EXPR_LABEL (stmt);
909 if (label == label_for_this_bb
910 || ! DECL_ARTIFICIAL (label)
911 || DECL_NONLOCAL (label))
921 /* Look for blocks ending in a multiway branch (a SWITCH_EXPR in GIMPLE),
922 and scan the sorted vector of cases. Combine the ones jumping to the
924 Eg. three separate entries 1: 2: 3: become one entry 1..3: */
927 group_case_labels (void)
933 tree stmt = last_stmt (bb);
934 if (stmt && TREE_CODE (stmt) == SWITCH_EXPR)
936 tree labels = SWITCH_LABELS (stmt);
937 int old_size = TREE_VEC_LENGTH (labels);
938 int i, j, new_size = old_size;
939 tree default_case = TREE_VEC_ELT (labels, old_size - 1);
942 /* The default label is always the last case in a switch
943 statement after gimplification. */
944 default_label = CASE_LABEL (default_case);
946 /* Look for possible opportunities to merge cases.
947 Ignore the last element of the label vector because it
948 must be the default case. */
950 while (i < old_size - 1)
952 tree base_case, base_label, base_high, type;
953 base_case = TREE_VEC_ELT (labels, i);
955 gcc_assert (base_case);
956 base_label = CASE_LABEL (base_case);
958 /* Discard cases that have the same destination as the
960 if (base_label == default_label)
962 TREE_VEC_ELT (labels, i) = NULL_TREE;
968 type = TREE_TYPE (CASE_LOW (base_case));
969 base_high = CASE_HIGH (base_case) ?
970 CASE_HIGH (base_case) : CASE_LOW (base_case);
972 /* Try to merge case labels. Break out when we reach the end
973 of the label vector or when we cannot merge the next case
974 label with the current one. */
975 while (i < old_size - 1)
977 tree merge_case = TREE_VEC_ELT (labels, i);
978 tree merge_label = CASE_LABEL (merge_case);
979 tree t = int_const_binop (PLUS_EXPR, base_high,
980 integer_one_node, 1);
982 /* Merge the cases if they jump to the same place,
983 and their ranges are consecutive. */
984 if (merge_label == base_label
985 && tree_int_cst_equal (CASE_LOW (merge_case), t))
987 base_high = CASE_HIGH (merge_case) ?
988 CASE_HIGH (merge_case) : CASE_LOW (merge_case);
989 CASE_HIGH (base_case) = base_high;
990 TREE_VEC_ELT (labels, i) = NULL_TREE;
999 /* Compress the case labels in the label vector, and adjust the
1000 length of the vector. */
1001 for (i = 0, j = 0; i < new_size; i++)
1003 while (! TREE_VEC_ELT (labels, j))
1005 TREE_VEC_ELT (labels, i) = TREE_VEC_ELT (labels, j++);
1007 TREE_VEC_LENGTH (labels) = new_size;
1012 /* Checks whether we can merge block B into block A. */
1015 tree_can_merge_blocks_p (basic_block a, basic_block b)
1018 block_stmt_iterator bsi;
1020 if (EDGE_COUNT (a->succs) != 1)
1023 if (EDGE_SUCC (a, 0)->flags & EDGE_ABNORMAL)
1026 if (EDGE_SUCC (a, 0)->dest != b)
1029 if (b == EXIT_BLOCK_PTR)
1032 if (EDGE_COUNT (b->preds) > 1)
1035 /* If A ends by a statement causing exceptions or something similar, we
1036 cannot merge the blocks. */
1037 stmt = last_stmt (a);
1038 if (stmt && stmt_ends_bb_p (stmt))
1041 /* Do not allow a block with only a non-local label to be merged. */
1042 if (stmt && TREE_CODE (stmt) == LABEL_EXPR
1043 && DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)))
1046 /* There may be no phi nodes at the start of b. Most of these degenerate
1047 phi nodes should be cleaned up by kill_redundant_phi_nodes. */
1051 /* Do not remove user labels. */
1052 for (bsi = bsi_start (b); !bsi_end_p (bsi); bsi_next (&bsi))
1054 stmt = bsi_stmt (bsi);
1055 if (TREE_CODE (stmt) != LABEL_EXPR)
1057 if (!DECL_ARTIFICIAL (LABEL_EXPR_LABEL (stmt)))
1065 /* Merge block B into block A. */
1068 tree_merge_blocks (basic_block a, basic_block b)
1070 block_stmt_iterator bsi;
1071 tree_stmt_iterator last;
1074 fprintf (dump_file, "Merging blocks %d and %d\n", a->index, b->index);
1076 /* Ensure that B follows A. */
1077 move_block_after (b, a);
1079 gcc_assert (EDGE_SUCC (a, 0)->flags & EDGE_FALLTHRU);
1080 gcc_assert (!last_stmt (a) || !stmt_ends_bb_p (last_stmt (a)));
1082 /* Remove labels from B and set bb_for_stmt to A for other statements. */
1083 for (bsi = bsi_start (b); !bsi_end_p (bsi);)
1085 if (TREE_CODE (bsi_stmt (bsi)) == LABEL_EXPR)
1089 set_bb_for_stmt (bsi_stmt (bsi), a);
1094 /* Merge the chains. */
1095 last = tsi_last (a->stmt_list);
1096 tsi_link_after (&last, b->stmt_list, TSI_NEW_STMT);
1097 b->stmt_list = NULL;
1101 /* Walk the function tree removing unnecessary statements.
1103 * Empty statement nodes are removed
1105 * Unnecessary TRY_FINALLY and TRY_CATCH blocks are removed
1107 * Unnecessary COND_EXPRs are removed
1109 * Some unnecessary BIND_EXPRs are removed
1111 Clearly more work could be done. The trick is doing the analysis
1112 and removal fast enough to be a net improvement in compile times.
1114 Note that when we remove a control structure such as a COND_EXPR
1115 BIND_EXPR, or TRY block, we will need to repeat this optimization pass
1116 to ensure we eliminate all the useless code. */
1127 static void remove_useless_stmts_1 (tree *, struct rus_data *);
1130 remove_useless_stmts_warn_notreached (tree stmt)
1132 if (EXPR_HAS_LOCATION (stmt))
1134 location_t loc = EXPR_LOCATION (stmt);
1135 warning ("%Hwill never be executed", &loc);
1139 switch (TREE_CODE (stmt))
1141 case STATEMENT_LIST:
1143 tree_stmt_iterator i;
1144 for (i = tsi_start (stmt); !tsi_end_p (i); tsi_next (&i))
1145 if (remove_useless_stmts_warn_notreached (tsi_stmt (i)))
1151 if (remove_useless_stmts_warn_notreached (COND_EXPR_COND (stmt)))
1153 if (remove_useless_stmts_warn_notreached (COND_EXPR_THEN (stmt)))
1155 if (remove_useless_stmts_warn_notreached (COND_EXPR_ELSE (stmt)))
1159 case TRY_FINALLY_EXPR:
1160 case TRY_CATCH_EXPR:
1161 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt, 0)))
1163 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt, 1)))
1168 return remove_useless_stmts_warn_notreached (CATCH_BODY (stmt));
1169 case EH_FILTER_EXPR:
1170 return remove_useless_stmts_warn_notreached (EH_FILTER_FAILURE (stmt));
1172 return remove_useless_stmts_warn_notreached (BIND_EXPR_BLOCK (stmt));
1175 /* Not a live container. */
1183 remove_useless_stmts_cond (tree *stmt_p, struct rus_data *data)
1185 tree then_clause, else_clause, cond;
1186 bool save_has_label, then_has_label, else_has_label;
1188 save_has_label = data->has_label;
1189 data->has_label = false;
1190 data->last_goto = NULL;
1192 remove_useless_stmts_1 (&COND_EXPR_THEN (*stmt_p), data);
1194 then_has_label = data->has_label;
1195 data->has_label = false;
1196 data->last_goto = NULL;
1198 remove_useless_stmts_1 (&COND_EXPR_ELSE (*stmt_p), data);
1200 else_has_label = data->has_label;
1201 data->has_label = save_has_label | then_has_label | else_has_label;
1203 then_clause = COND_EXPR_THEN (*stmt_p);
1204 else_clause = COND_EXPR_ELSE (*stmt_p);
1205 cond = COND_EXPR_COND (*stmt_p);
1207 /* If neither arm does anything at all, we can remove the whole IF. */
1208 if (!TREE_SIDE_EFFECTS (then_clause) && !TREE_SIDE_EFFECTS (else_clause))
1210 *stmt_p = build_empty_stmt ();
1211 data->repeat = true;
1214 /* If there are no reachable statements in an arm, then we can
1215 zap the entire conditional. */
1216 else if (integer_nonzerop (cond) && !else_has_label)
1218 if (warn_notreached)
1219 remove_useless_stmts_warn_notreached (else_clause);
1220 *stmt_p = then_clause;
1221 data->repeat = true;
1223 else if (integer_zerop (cond) && !then_has_label)
1225 if (warn_notreached)
1226 remove_useless_stmts_warn_notreached (then_clause);
1227 *stmt_p = else_clause;
1228 data->repeat = true;
1231 /* Check a couple of simple things on then/else with single stmts. */
1234 tree then_stmt = expr_only (then_clause);
1235 tree else_stmt = expr_only (else_clause);
1237 /* Notice branches to a common destination. */
1238 if (then_stmt && else_stmt
1239 && TREE_CODE (then_stmt) == GOTO_EXPR
1240 && TREE_CODE (else_stmt) == GOTO_EXPR
1241 && (GOTO_DESTINATION (then_stmt) == GOTO_DESTINATION (else_stmt)))
1243 *stmt_p = then_stmt;
1244 data->repeat = true;
1247 /* If the THEN/ELSE clause merely assigns a value to a variable or
1248 parameter which is already known to contain that value, then
1249 remove the useless THEN/ELSE clause. */
1250 else if (TREE_CODE (cond) == VAR_DECL || TREE_CODE (cond) == PARM_DECL)
1253 && TREE_CODE (else_stmt) == MODIFY_EXPR
1254 && TREE_OPERAND (else_stmt, 0) == cond
1255 && integer_zerop (TREE_OPERAND (else_stmt, 1)))
1256 COND_EXPR_ELSE (*stmt_p) = alloc_stmt_list ();
1258 else if ((TREE_CODE (cond) == EQ_EXPR || TREE_CODE (cond) == NE_EXPR)
1259 && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL
1260 || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL)
1261 && TREE_CONSTANT (TREE_OPERAND (cond, 1)))
1263 tree stmt = (TREE_CODE (cond) == EQ_EXPR
1264 ? then_stmt : else_stmt);
1265 tree *location = (TREE_CODE (cond) == EQ_EXPR
1266 ? &COND_EXPR_THEN (*stmt_p)
1267 : &COND_EXPR_ELSE (*stmt_p));
1270 && TREE_CODE (stmt) == MODIFY_EXPR
1271 && TREE_OPERAND (stmt, 0) == TREE_OPERAND (cond, 0)
1272 && TREE_OPERAND (stmt, 1) == TREE_OPERAND (cond, 1))
1273 *location = alloc_stmt_list ();
1277 /* Protect GOTOs in the arm of COND_EXPRs from being removed. They
1278 would be re-introduced during lowering. */
1279 data->last_goto = NULL;
1284 remove_useless_stmts_tf (tree *stmt_p, struct rus_data *data)
1286 bool save_may_branch, save_may_throw;
1287 bool this_may_branch, this_may_throw;
1289 /* Collect may_branch and may_throw information for the body only. */
1290 save_may_branch = data->may_branch;
1291 save_may_throw = data->may_throw;
1292 data->may_branch = false;
1293 data->may_throw = false;
1294 data->last_goto = NULL;
1296 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 0), data);
1298 this_may_branch = data->may_branch;
1299 this_may_throw = data->may_throw;
1300 data->may_branch |= save_may_branch;
1301 data->may_throw |= save_may_throw;
1302 data->last_goto = NULL;
1304 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 1), data);
1306 /* If the body is empty, then we can emit the FINALLY block without
1307 the enclosing TRY_FINALLY_EXPR. */
1308 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 0)))
1310 *stmt_p = TREE_OPERAND (*stmt_p, 1);
1311 data->repeat = true;
1314 /* If the handler is empty, then we can emit the TRY block without
1315 the enclosing TRY_FINALLY_EXPR. */
1316 else if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 1)))
1318 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1319 data->repeat = true;
1322 /* If the body neither throws, nor branches, then we can safely
1323 string the TRY and FINALLY blocks together. */
1324 else if (!this_may_branch && !this_may_throw)
1326 tree stmt = *stmt_p;
1327 *stmt_p = TREE_OPERAND (stmt, 0);
1328 append_to_statement_list (TREE_OPERAND (stmt, 1), stmt_p);
1329 data->repeat = true;
1335 remove_useless_stmts_tc (tree *stmt_p, struct rus_data *data)
1337 bool save_may_throw, this_may_throw;
1338 tree_stmt_iterator i;
1341 /* Collect may_throw information for the body only. */
1342 save_may_throw = data->may_throw;
1343 data->may_throw = false;
1344 data->last_goto = NULL;
1346 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 0), data);
1348 this_may_throw = data->may_throw;
1349 data->may_throw = save_may_throw;
1351 /* If the body cannot throw, then we can drop the entire TRY_CATCH_EXPR. */
1352 if (!this_may_throw)
1354 if (warn_notreached)
1355 remove_useless_stmts_warn_notreached (TREE_OPERAND (*stmt_p, 1));
1356 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1357 data->repeat = true;
1361 /* Process the catch clause specially. We may be able to tell that
1362 no exceptions propagate past this point. */
1364 this_may_throw = true;
1365 i = tsi_start (TREE_OPERAND (*stmt_p, 1));
1366 stmt = tsi_stmt (i);
1367 data->last_goto = NULL;
1369 switch (TREE_CODE (stmt))
1372 for (; !tsi_end_p (i); tsi_next (&i))
1374 stmt = tsi_stmt (i);
1375 /* If we catch all exceptions, then the body does not
1376 propagate exceptions past this point. */
1377 if (CATCH_TYPES (stmt) == NULL)
1378 this_may_throw = false;
1379 data->last_goto = NULL;
1380 remove_useless_stmts_1 (&CATCH_BODY (stmt), data);
1384 case EH_FILTER_EXPR:
1385 if (EH_FILTER_MUST_NOT_THROW (stmt))
1386 this_may_throw = false;
1387 else if (EH_FILTER_TYPES (stmt) == NULL)
1388 this_may_throw = false;
1389 remove_useless_stmts_1 (&EH_FILTER_FAILURE (stmt), data);
1393 /* Otherwise this is a cleanup. */
1394 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 1), data);
1396 /* If the cleanup is empty, then we can emit the TRY block without
1397 the enclosing TRY_CATCH_EXPR. */
1398 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 1)))
1400 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1401 data->repeat = true;
1405 data->may_throw |= this_may_throw;
1410 remove_useless_stmts_bind (tree *stmt_p, struct rus_data *data)
1414 /* First remove anything underneath the BIND_EXPR. */
1415 remove_useless_stmts_1 (&BIND_EXPR_BODY (*stmt_p), data);
1417 /* If the BIND_EXPR has no variables, then we can pull everything
1418 up one level and remove the BIND_EXPR, unless this is the toplevel
1419 BIND_EXPR for the current function or an inlined function.
1421 When this situation occurs we will want to apply this
1422 optimization again. */
1423 block = BIND_EXPR_BLOCK (*stmt_p);
1424 if (BIND_EXPR_VARS (*stmt_p) == NULL_TREE
1425 && *stmt_p != DECL_SAVED_TREE (current_function_decl)
1427 || ! BLOCK_ABSTRACT_ORIGIN (block)
1428 || (TREE_CODE (BLOCK_ABSTRACT_ORIGIN (block))
1431 *stmt_p = BIND_EXPR_BODY (*stmt_p);
1432 data->repeat = true;
1438 remove_useless_stmts_goto (tree *stmt_p, struct rus_data *data)
1440 tree dest = GOTO_DESTINATION (*stmt_p);
1442 data->may_branch = true;
1443 data->last_goto = NULL;
1445 /* Record the last goto expr, so that we can delete it if unnecessary. */
1446 if (TREE_CODE (dest) == LABEL_DECL)
1447 data->last_goto = stmt_p;
1452 remove_useless_stmts_label (tree *stmt_p, struct rus_data *data)
1454 tree label = LABEL_EXPR_LABEL (*stmt_p);
1456 data->has_label = true;
1458 /* We do want to jump across non-local label receiver code. */
1459 if (DECL_NONLOCAL (label))
1460 data->last_goto = NULL;
1462 else if (data->last_goto && GOTO_DESTINATION (*data->last_goto) == label)
1464 *data->last_goto = build_empty_stmt ();
1465 data->repeat = true;
1468 /* ??? Add something here to delete unused labels. */
1472 /* If the function is "const" or "pure", then clear TREE_SIDE_EFFECTS on its
1473 decl. This allows us to eliminate redundant or useless
1474 calls to "const" functions.
1476 Gimplifier already does the same operation, but we may notice functions
1477 being const and pure once their calls has been gimplified, so we need
1478 to update the flag. */
1481 update_call_expr_flags (tree call)
1483 tree decl = get_callee_fndecl (call);
1486 if (call_expr_flags (call) & (ECF_CONST | ECF_PURE))
1487 TREE_SIDE_EFFECTS (call) = 0;
1488 if (TREE_NOTHROW (decl))
1489 TREE_NOTHROW (call) = 1;
1493 /* T is CALL_EXPR. Set current_function_calls_* flags. */
1496 notice_special_calls (tree t)
1498 int flags = call_expr_flags (t);
1500 if (flags & ECF_MAY_BE_ALLOCA)
1501 current_function_calls_alloca = true;
1502 if (flags & ECF_RETURNS_TWICE)
1503 current_function_calls_setjmp = true;
1507 /* Clear flags set by notice_special_calls. Used by dead code removal
1508 to update the flags. */
1511 clear_special_calls (void)
1513 current_function_calls_alloca = false;
1514 current_function_calls_setjmp = false;
1519 remove_useless_stmts_1 (tree *tp, struct rus_data *data)
1523 switch (TREE_CODE (t))
1526 remove_useless_stmts_cond (tp, data);
1529 case TRY_FINALLY_EXPR:
1530 remove_useless_stmts_tf (tp, data);
1533 case TRY_CATCH_EXPR:
1534 remove_useless_stmts_tc (tp, data);
1538 remove_useless_stmts_bind (tp, data);
1542 remove_useless_stmts_goto (tp, data);
1546 remove_useless_stmts_label (tp, data);
1551 data->last_goto = NULL;
1552 data->may_branch = true;
1557 data->last_goto = NULL;
1558 notice_special_calls (t);
1559 update_call_expr_flags (t);
1560 if (tree_could_throw_p (t))
1561 data->may_throw = true;
1565 data->last_goto = NULL;
1567 op = get_call_expr_in (t);
1570 update_call_expr_flags (op);
1571 notice_special_calls (op);
1573 if (tree_could_throw_p (t))
1574 data->may_throw = true;
1577 case STATEMENT_LIST:
1579 tree_stmt_iterator i = tsi_start (t);
1580 while (!tsi_end_p (i))
1583 if (IS_EMPTY_STMT (t))
1589 remove_useless_stmts_1 (tsi_stmt_ptr (i), data);
1592 if (TREE_CODE (t) == STATEMENT_LIST)
1594 tsi_link_before (&i, t, TSI_SAME_STMT);
1604 data->last_goto = NULL;
1608 data->last_goto = NULL;
1614 remove_useless_stmts (void)
1616 struct rus_data data;
1618 clear_special_calls ();
1622 memset (&data, 0, sizeof (data));
1623 remove_useless_stmts_1 (&DECL_SAVED_TREE (current_function_decl), &data);
1625 while (data.repeat);
1629 struct tree_opt_pass pass_remove_useless_stmts =
1631 "useless", /* name */
1633 remove_useless_stmts, /* execute */
1636 0, /* static_pass_number */
1638 PROP_gimple_any, /* properties_required */
1639 0, /* properties_provided */
1640 0, /* properties_destroyed */
1641 0, /* todo_flags_start */
1642 TODO_dump_func, /* todo_flags_finish */
1647 /* Remove obviously useless statements in basic block BB. */
1650 cfg_remove_useless_stmts_bb (basic_block bb)
1652 block_stmt_iterator bsi;
1653 tree stmt = NULL_TREE;
1654 tree cond, var = NULL_TREE, val = NULL_TREE;
1655 struct var_ann_d *ann;
1657 /* Check whether we come here from a condition, and if so, get the
1659 if (EDGE_COUNT (bb->preds) != 1
1660 || !(EDGE_PRED (bb, 0)->flags & (EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
1663 cond = COND_EXPR_COND (last_stmt (EDGE_PRED (bb, 0)->src));
1665 if (TREE_CODE (cond) == VAR_DECL || TREE_CODE (cond) == PARM_DECL)
1668 val = (EDGE_PRED (bb, 0)->flags & EDGE_FALSE_VALUE
1669 ? boolean_false_node : boolean_true_node);
1671 else if (TREE_CODE (cond) == TRUTH_NOT_EXPR
1672 && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL
1673 || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL))
1675 var = TREE_OPERAND (cond, 0);
1676 val = (EDGE_PRED (bb, 0)->flags & EDGE_FALSE_VALUE
1677 ? boolean_true_node : boolean_false_node);
1681 if (EDGE_PRED (bb, 0)->flags & EDGE_FALSE_VALUE)
1682 cond = invert_truthvalue (cond);
1683 if (TREE_CODE (cond) == EQ_EXPR
1684 && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL
1685 || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL)
1686 && (TREE_CODE (TREE_OPERAND (cond, 1)) == VAR_DECL
1687 || TREE_CODE (TREE_OPERAND (cond, 1)) == PARM_DECL
1688 || TREE_CONSTANT (TREE_OPERAND (cond, 1))))
1690 var = TREE_OPERAND (cond, 0);
1691 val = TREE_OPERAND (cond, 1);
1697 /* Only work for normal local variables. */
1698 ann = var_ann (var);
1701 || TREE_ADDRESSABLE (var))
1704 if (! TREE_CONSTANT (val))
1706 ann = var_ann (val);
1709 || TREE_ADDRESSABLE (val))
1713 /* Ignore floating point variables, since comparison behaves weird for
1715 if (FLOAT_TYPE_P (TREE_TYPE (var)))
1718 for (bsi = bsi_start (bb); !bsi_end_p (bsi);)
1720 stmt = bsi_stmt (bsi);
1722 /* If the THEN/ELSE clause merely assigns a value to a variable/parameter
1723 which is already known to contain that value, then remove the useless
1724 THEN/ELSE clause. */
1725 if (TREE_CODE (stmt) == MODIFY_EXPR
1726 && TREE_OPERAND (stmt, 0) == var
1727 && operand_equal_p (val, TREE_OPERAND (stmt, 1), 0))
1733 /* Invalidate the var if we encounter something that could modify it.
1734 Likewise for the value it was previously set to. Note that we only
1735 consider values that are either a VAR_DECL or PARM_DECL so we
1736 can test for conflict very simply. */
1737 if (TREE_CODE (stmt) == ASM_EXPR
1738 || (TREE_CODE (stmt) == MODIFY_EXPR
1739 && (TREE_OPERAND (stmt, 0) == var
1740 || TREE_OPERAND (stmt, 0) == val)))
1748 /* A CFG-aware version of remove_useless_stmts. */
1751 cfg_remove_useless_stmts (void)
1755 #ifdef ENABLE_CHECKING
1756 verify_flow_info ();
1761 cfg_remove_useless_stmts_bb (bb);
1766 /* Remove PHI nodes associated with basic block BB and all edges out of BB. */
1769 remove_phi_nodes_and_edges_for_unreachable_block (basic_block bb)
1773 /* Since this block is no longer reachable, we can just delete all
1774 of its PHI nodes. */
1775 phi = phi_nodes (bb);
1778 tree next = PHI_CHAIN (phi);
1779 remove_phi_node (phi, NULL_TREE, bb);
1783 /* Remove edges to BB's successors. */
1784 while (EDGE_COUNT (bb->succs) > 0)
1785 ssa_remove_edge (EDGE_SUCC (bb, 0));
1789 /* Remove statements of basic block BB. */
1792 remove_bb (basic_block bb)
1794 block_stmt_iterator i;
1795 source_locus loc = 0;
1799 fprintf (dump_file, "Removing basic block %d\n", bb->index);
1800 if (dump_flags & TDF_DETAILS)
1802 dump_bb (bb, dump_file, 0);
1803 fprintf (dump_file, "\n");
1807 /* Remove all the instructions in the block. */
1808 for (i = bsi_start (bb); !bsi_end_p (i);)
1810 tree stmt = bsi_stmt (i);
1811 if (TREE_CODE (stmt) == LABEL_EXPR
1812 && FORCED_LABEL (LABEL_EXPR_LABEL (stmt)))
1814 basic_block new_bb = bb->prev_bb;
1815 block_stmt_iterator new_bsi = bsi_after_labels (new_bb);
1818 bsi_insert_after (&new_bsi, stmt, BSI_NEW_STMT);
1822 release_defs (stmt);
1824 set_bb_for_stmt (stmt, NULL);
1828 /* Don't warn for removed gotos. Gotos are often removed due to
1829 jump threading, thus resulting in bogus warnings. Not great,
1830 since this way we lose warnings for gotos in the original
1831 program that are indeed unreachable. */
1832 if (TREE_CODE (stmt) != GOTO_EXPR && EXPR_HAS_LOCATION (stmt) && !loc)
1833 #ifdef USE_MAPPED_LOCATION
1834 loc = EXPR_LOCATION (stmt);
1836 loc = EXPR_LOCUS (stmt);
1840 /* If requested, give a warning that the first statement in the
1841 block is unreachable. We walk statements backwards in the
1842 loop above, so the last statement we process is the first statement
1844 if (warn_notreached && loc)
1845 #ifdef USE_MAPPED_LOCATION
1846 warning ("%Hwill never be executed", &loc);
1848 warning ("%Hwill never be executed", loc);
1851 remove_phi_nodes_and_edges_for_unreachable_block (bb);
1854 /* Try to remove superfluous control structures. */
1857 cleanup_control_flow (void)
1860 block_stmt_iterator bsi;
1861 bool retval = false;
1866 bsi = bsi_last (bb);
1868 if (bsi_end_p (bsi))
1871 stmt = bsi_stmt (bsi);
1872 if (TREE_CODE (stmt) == COND_EXPR
1873 || TREE_CODE (stmt) == SWITCH_EXPR)
1874 retval |= cleanup_control_expr_graph (bb, bsi);
1880 /* Disconnect an unreachable block in the control expression starting
1884 cleanup_control_expr_graph (basic_block bb, block_stmt_iterator bsi)
1887 bool retval = false;
1888 tree expr = bsi_stmt (bsi), val;
1890 if (EDGE_COUNT (bb->succs) > 1)
1895 switch (TREE_CODE (expr))
1898 val = COND_EXPR_COND (expr);
1902 val = SWITCH_COND (expr);
1903 if (TREE_CODE (val) != INTEGER_CST)
1911 taken_edge = find_taken_edge (bb, val);
1915 /* Remove all the edges except the one that is always executed. */
1916 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
1918 if (e != taken_edge)
1920 taken_edge->probability += e->probability;
1921 taken_edge->count += e->count;
1922 ssa_remove_edge (e);
1928 if (taken_edge->probability > REG_BR_PROB_BASE)
1929 taken_edge->probability = REG_BR_PROB_BASE;
1932 taken_edge = EDGE_SUCC (bb, 0);
1935 taken_edge->flags = EDGE_FALLTHRU;
1937 /* We removed some paths from the cfg. */
1938 free_dominance_info (CDI_DOMINATORS);
1944 /* Given a basic block BB ending with COND_EXPR or SWITCH_EXPR, and a
1945 predicate VAL, return the edge that will be taken out of the block.
1946 If VAL does not match a unique edge, NULL is returned. */
1949 find_taken_edge (basic_block bb, tree val)
1953 stmt = last_stmt (bb);
1956 gcc_assert (is_ctrl_stmt (stmt));
1958 /* If VAL is a predicate of the form N RELOP N, where N is an
1959 SSA_NAME, we can usually determine its truth value. */
1960 if (val && COMPARISON_CLASS_P (val))
1963 /* If VAL is not a constant, we can't determine which edge might
1965 if (val == NULL || !really_constant_p (val))
1968 if (TREE_CODE (stmt) == COND_EXPR)
1969 return find_taken_edge_cond_expr (bb, val);
1971 if (TREE_CODE (stmt) == SWITCH_EXPR)
1972 return find_taken_edge_switch_expr (bb, val);
1978 /* Given a constant value VAL and the entry block BB to a COND_EXPR
1979 statement, determine which of the two edges will be taken out of the
1980 block. Return NULL if either edge may be taken. */
1983 find_taken_edge_cond_expr (basic_block bb, tree val)
1985 edge true_edge, false_edge;
1987 extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
1989 /* If both edges of the branch lead to the same basic block, it doesn't
1990 matter which edge is taken. */
1991 if (true_edge->dest == false_edge->dest)
1994 /* Otherwise, try to determine which branch of the if() will be taken.
1995 If VAL is a constant but it can't be reduced to a 0 or a 1, then
1996 we don't really know which edge will be taken at runtime. This
1997 may happen when comparing addresses (e.g., if (&var1 == 4)). */
1998 if (integer_nonzerop (val))
2000 else if (integer_zerop (val))
2007 /* Given a constant value VAL and the entry block BB to a SWITCH_EXPR
2008 statement, determine which edge will be taken out of the block. Return
2009 NULL if any edge may be taken. */
2012 find_taken_edge_switch_expr (basic_block bb, tree val)
2014 tree switch_expr, taken_case;
2015 basic_block dest_bb;
2018 if (TREE_CODE (val) != INTEGER_CST)
2021 switch_expr = last_stmt (bb);
2022 taken_case = find_case_label_for_value (switch_expr, val);
2023 dest_bb = label_to_block (CASE_LABEL (taken_case));
2025 e = find_edge (bb, dest_bb);
2031 /* Return the CASE_LABEL_EXPR that SWITCH_EXPR will take for VAL.
2032 We can make optimal use here of the fact that the case labels are
2033 sorted: We can do a binary search for a case matching VAL. */
2036 find_case_label_for_value (tree switch_expr, tree val)
2038 tree vec = SWITCH_LABELS (switch_expr);
2039 size_t low, high, n = TREE_VEC_LENGTH (vec);
2040 tree default_case = TREE_VEC_ELT (vec, n - 1);
2042 for (low = -1, high = n - 1; high - low > 1; )
2044 size_t i = (high + low) / 2;
2045 tree t = TREE_VEC_ELT (vec, i);
2048 /* Cache the result of comparing CASE_LOW and val. */
2049 cmp = tree_int_cst_compare (CASE_LOW (t), val);
2056 if (CASE_HIGH (t) == NULL)
2058 /* A singe-valued case label. */
2064 /* A case range. We can only handle integer ranges. */
2065 if (cmp <= 0 && tree_int_cst_compare (CASE_HIGH (t), val) >= 0)
2070 return default_case;
2074 /* If all the PHI nodes in DEST have alternatives for E1 and E2 and
2075 those alternatives are equal in each of the PHI nodes, then return
2076 true, else return false. */
2079 phi_alternatives_equal (basic_block dest, edge e1, edge e2)
2081 tree phi, val1, val2;
2084 for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi))
2086 n1 = phi_arg_from_edge (phi, e1);
2087 n2 = phi_arg_from_edge (phi, e2);
2089 gcc_assert (n1 >= 0);
2090 gcc_assert (n2 >= 0);
2092 val1 = PHI_ARG_DEF (phi, n1);
2093 val2 = PHI_ARG_DEF (phi, n2);
2095 if (!operand_equal_p (val1, val2, 0))
2103 /*---------------------------------------------------------------------------
2105 ---------------------------------------------------------------------------*/
2107 /* Dump tree-specific information of block BB to file OUTF. */
2110 tree_dump_bb (basic_block bb, FILE *outf, int indent)
2112 dump_generic_bb (outf, bb, indent, TDF_VOPS);
2116 /* Dump a basic block on stderr. */
2119 debug_tree_bb (basic_block bb)
2121 dump_bb (bb, stderr, 0);
2125 /* Dump basic block with index N on stderr. */
2128 debug_tree_bb_n (int n)
2130 debug_tree_bb (BASIC_BLOCK (n));
2131 return BASIC_BLOCK (n);
2135 /* Dump the CFG on stderr.
2137 FLAGS are the same used by the tree dumping functions
2138 (see TDF_* in tree.h). */
2141 debug_tree_cfg (int flags)
2143 dump_tree_cfg (stderr, flags);
2147 /* Dump the program showing basic block boundaries on the given FILE.
2149 FLAGS are the same used by the tree dumping functions (see TDF_* in
2153 dump_tree_cfg (FILE *file, int flags)
2155 if (flags & TDF_DETAILS)
2157 const char *funcname
2158 = lang_hooks.decl_printable_name (current_function_decl, 2);
2161 fprintf (file, ";; Function %s\n\n", funcname);
2162 fprintf (file, ";; \n%d basic blocks, %d edges, last basic block %d.\n\n",
2163 n_basic_blocks, n_edges, last_basic_block);
2165 brief_dump_cfg (file);
2166 fprintf (file, "\n");
2169 if (flags & TDF_STATS)
2170 dump_cfg_stats (file);
2172 dump_function_to_file (current_function_decl, file, flags | TDF_BLOCKS);
2176 /* Dump CFG statistics on FILE. */
2179 dump_cfg_stats (FILE *file)
2181 static long max_num_merged_labels = 0;
2182 unsigned long size, total = 0;
2185 const char * const fmt_str = "%-30s%-13s%12s\n";
2186 const char * const fmt_str_1 = "%-30s%13d%11lu%c\n";
2187 const char * const fmt_str_3 = "%-43s%11lu%c\n";
2188 const char *funcname
2189 = lang_hooks.decl_printable_name (current_function_decl, 2);
2192 fprintf (file, "\nCFG Statistics for %s\n\n", funcname);
2194 fprintf (file, "---------------------------------------------------------\n");
2195 fprintf (file, fmt_str, "", " Number of ", "Memory");
2196 fprintf (file, fmt_str, "", " instances ", "used ");
2197 fprintf (file, "---------------------------------------------------------\n");
2199 size = n_basic_blocks * sizeof (struct basic_block_def);
2201 fprintf (file, fmt_str_1, "Basic blocks", n_basic_blocks,
2202 SCALE (size), LABEL (size));
2206 n_edges += EDGE_COUNT (bb->succs);
2207 size = n_edges * sizeof (struct edge_def);
2209 fprintf (file, fmt_str_1, "Edges", n_edges, SCALE (size), LABEL (size));
2211 size = n_basic_blocks * sizeof (struct bb_ann_d);
2213 fprintf (file, fmt_str_1, "Basic block annotations", n_basic_blocks,
2214 SCALE (size), LABEL (size));
2216 fprintf (file, "---------------------------------------------------------\n");
2217 fprintf (file, fmt_str_3, "Total memory used by CFG data", SCALE (total),
2219 fprintf (file, "---------------------------------------------------------\n");
2220 fprintf (file, "\n");
2222 if (cfg_stats.num_merged_labels > max_num_merged_labels)
2223 max_num_merged_labels = cfg_stats.num_merged_labels;
2225 fprintf (file, "Coalesced label blocks: %ld (Max so far: %ld)\n",
2226 cfg_stats.num_merged_labels, max_num_merged_labels);
2228 fprintf (file, "\n");
2232 /* Dump CFG statistics on stderr. Keep extern so that it's always
2233 linked in the final executable. */
2236 debug_cfg_stats (void)
2238 dump_cfg_stats (stderr);
2242 /* Dump the flowgraph to a .vcg FILE. */
2245 tree_cfg2vcg (FILE *file)
2250 const char *funcname
2251 = lang_hooks.decl_printable_name (current_function_decl, 2);
2253 /* Write the file header. */
2254 fprintf (file, "graph: { title: \"%s\"\n", funcname);
2255 fprintf (file, "node: { title: \"ENTRY\" label: \"ENTRY\" }\n");
2256 fprintf (file, "node: { title: \"EXIT\" label: \"EXIT\" }\n");
2258 /* Write blocks and edges. */
2259 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
2261 fprintf (file, "edge: { sourcename: \"ENTRY\" targetname: \"%d\"",
2264 if (e->flags & EDGE_FAKE)
2265 fprintf (file, " linestyle: dotted priority: 10");
2267 fprintf (file, " linestyle: solid priority: 100");
2269 fprintf (file, " }\n");
2275 enum tree_code head_code, end_code;
2276 const char *head_name, *end_name;
2279 tree first = first_stmt (bb);
2280 tree last = last_stmt (bb);
2284 head_code = TREE_CODE (first);
2285 head_name = tree_code_name[head_code];
2286 head_line = get_lineno (first);
2289 head_name = "no-statement";
2293 end_code = TREE_CODE (last);
2294 end_name = tree_code_name[end_code];
2295 end_line = get_lineno (last);
2298 end_name = "no-statement";
2300 fprintf (file, "node: { title: \"%d\" label: \"#%d\\n%s (%d)\\n%s (%d)\"}\n",
2301 bb->index, bb->index, head_name, head_line, end_name,
2304 FOR_EACH_EDGE (e, ei, bb->succs)
2306 if (e->dest == EXIT_BLOCK_PTR)
2307 fprintf (file, "edge: { sourcename: \"%d\" targetname: \"EXIT\"", bb->index);
2309 fprintf (file, "edge: { sourcename: \"%d\" targetname: \"%d\"", bb->index, e->dest->index);
2311 if (e->flags & EDGE_FAKE)
2312 fprintf (file, " priority: 10 linestyle: dotted");
2314 fprintf (file, " priority: 100 linestyle: solid");
2316 fprintf (file, " }\n");
2319 if (bb->next_bb != EXIT_BLOCK_PTR)
2323 fputs ("}\n\n", file);
2328 /*---------------------------------------------------------------------------
2329 Miscellaneous helpers
2330 ---------------------------------------------------------------------------*/
2332 /* Return true if T represents a stmt that always transfers control. */
2335 is_ctrl_stmt (tree t)
2337 return (TREE_CODE (t) == COND_EXPR
2338 || TREE_CODE (t) == SWITCH_EXPR
2339 || TREE_CODE (t) == GOTO_EXPR
2340 || TREE_CODE (t) == RETURN_EXPR
2341 || TREE_CODE (t) == RESX_EXPR);
2345 /* Return true if T is a statement that may alter the flow of control
2346 (e.g., a call to a non-returning function). */
2349 is_ctrl_altering_stmt (tree t)
2354 call = get_call_expr_in (t);
2357 /* A non-pure/const CALL_EXPR alters flow control if the current
2358 function has nonlocal labels. */
2359 if (TREE_SIDE_EFFECTS (call) && current_function_has_nonlocal_label)
2362 /* A CALL_EXPR also alters control flow if it does not return. */
2363 if (call_expr_flags (call) & (ECF_NORETURN | ECF_LONGJMP))
2367 /* If a statement can throw, it alters control flow. */
2368 return tree_can_throw_internal (t);
2372 /* Return true if T is a computed goto. */
2375 computed_goto_p (tree t)
2377 return (TREE_CODE (t) == GOTO_EXPR
2378 && TREE_CODE (GOTO_DESTINATION (t)) != LABEL_DECL);
2382 /* Checks whether EXPR is a simple local goto. */
2385 simple_goto_p (tree expr)
2387 return (TREE_CODE (expr) == GOTO_EXPR
2388 && TREE_CODE (GOTO_DESTINATION (expr)) == LABEL_DECL);
2392 /* Return true if T should start a new basic block. PREV_T is the
2393 statement preceding T. It is used when T is a label or a case label.
2394 Labels should only start a new basic block if their previous statement
2395 wasn't a label. Otherwise, sequence of labels would generate
2396 unnecessary basic blocks that only contain a single label. */
2399 stmt_starts_bb_p (tree t, tree prev_t)
2401 enum tree_code code;
2406 /* LABEL_EXPRs start a new basic block only if the preceding
2407 statement wasn't a label of the same type. This prevents the
2408 creation of consecutive blocks that have nothing but a single
2410 code = TREE_CODE (t);
2411 if (code == LABEL_EXPR)
2413 /* Nonlocal and computed GOTO targets always start a new block. */
2414 if (code == LABEL_EXPR
2415 && (DECL_NONLOCAL (LABEL_EXPR_LABEL (t))
2416 || FORCED_LABEL (LABEL_EXPR_LABEL (t))))
2419 if (prev_t && TREE_CODE (prev_t) == code)
2421 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (prev_t)))
2424 cfg_stats.num_merged_labels++;
2435 /* Return true if T should end a basic block. */
2438 stmt_ends_bb_p (tree t)
2440 return is_ctrl_stmt (t) || is_ctrl_altering_stmt (t);
2444 /* Add gotos that used to be represented implicitly in the CFG. */
2447 disband_implicit_edges (void)
2450 block_stmt_iterator last;
2457 last = bsi_last (bb);
2458 stmt = last_stmt (bb);
2460 if (stmt && TREE_CODE (stmt) == COND_EXPR)
2462 /* Remove superfluous gotos from COND_EXPR branches. Moved
2463 from cfg_remove_useless_stmts here since it violates the
2464 invariants for tree--cfg correspondence and thus fits better
2465 here where we do it anyway. */
2466 FOR_EACH_EDGE (e, ei, bb->succs)
2468 if (e->dest != bb->next_bb)
2471 if (e->flags & EDGE_TRUE_VALUE)
2472 COND_EXPR_THEN (stmt) = build_empty_stmt ();
2473 else if (e->flags & EDGE_FALSE_VALUE)
2474 COND_EXPR_ELSE (stmt) = build_empty_stmt ();
2477 e->flags |= EDGE_FALLTHRU;
2483 if (stmt && TREE_CODE (stmt) == RETURN_EXPR)
2485 /* Remove the RETURN_EXPR if we may fall though to the exit
2487 gcc_assert (EDGE_COUNT (bb->succs) == 1);
2488 gcc_assert (EDGE_SUCC (bb, 0)->dest == EXIT_BLOCK_PTR);
2490 if (bb->next_bb == EXIT_BLOCK_PTR
2491 && !TREE_OPERAND (stmt, 0))
2494 EDGE_SUCC (bb, 0)->flags |= EDGE_FALLTHRU;
2499 /* There can be no fallthru edge if the last statement is a control
2501 if (stmt && is_ctrl_stmt (stmt))
2504 /* Find a fallthru edge and emit the goto if necessary. */
2505 FOR_EACH_EDGE (e, ei, bb->succs)
2506 if (e->flags & EDGE_FALLTHRU)
2509 if (!e || e->dest == bb->next_bb)
2512 gcc_assert (e->dest != EXIT_BLOCK_PTR);
2513 label = tree_block_label (e->dest);
2515 stmt = build1 (GOTO_EXPR, void_type_node, label);
2516 #ifdef USE_MAPPED_LOCATION
2517 SET_EXPR_LOCATION (stmt, e->goto_locus);
2519 SET_EXPR_LOCUS (stmt, e->goto_locus);
2521 bsi_insert_after (&last, stmt, BSI_NEW_STMT);
2522 e->flags &= ~EDGE_FALLTHRU;
2526 /* Remove block annotations and other datastructures. */
2529 delete_tree_cfg_annotations (void)
2532 if (n_basic_blocks > 0)
2533 free_blocks_annotations ();
2535 label_to_block_map = NULL;
2542 /* Return the first statement in basic block BB. */
2545 first_stmt (basic_block bb)
2547 block_stmt_iterator i = bsi_start (bb);
2548 return !bsi_end_p (i) ? bsi_stmt (i) : NULL_TREE;
2552 /* Return the last statement in basic block BB. */
2555 last_stmt (basic_block bb)
2557 block_stmt_iterator b = bsi_last (bb);
2558 return !bsi_end_p (b) ? bsi_stmt (b) : NULL_TREE;
2562 /* Return a pointer to the last statement in block BB. */
2565 last_stmt_ptr (basic_block bb)
2567 block_stmt_iterator last = bsi_last (bb);
2568 return !bsi_end_p (last) ? bsi_stmt_ptr (last) : NULL;
2572 /* Return the last statement of an otherwise empty block. Return NULL
2573 if the block is totally empty, or if it contains more than one
2577 last_and_only_stmt (basic_block bb)
2579 block_stmt_iterator i = bsi_last (bb);
2585 last = bsi_stmt (i);
2590 /* Empty statements should no longer appear in the instruction stream.
2591 Everything that might have appeared before should be deleted by
2592 remove_useless_stmts, and the optimizers should just bsi_remove
2593 instead of smashing with build_empty_stmt.
2595 Thus the only thing that should appear here in a block containing
2596 one executable statement is a label. */
2597 prev = bsi_stmt (i);
2598 if (TREE_CODE (prev) == LABEL_EXPR)
2605 /* Mark BB as the basic block holding statement T. */
2608 set_bb_for_stmt (tree t, basic_block bb)
2610 if (TREE_CODE (t) == PHI_NODE)
2612 else if (TREE_CODE (t) == STATEMENT_LIST)
2614 tree_stmt_iterator i;
2615 for (i = tsi_start (t); !tsi_end_p (i); tsi_next (&i))
2616 set_bb_for_stmt (tsi_stmt (i), bb);
2620 stmt_ann_t ann = get_stmt_ann (t);
2623 /* If the statement is a label, add the label to block-to-labels map
2624 so that we can speed up edge creation for GOTO_EXPRs. */
2625 if (TREE_CODE (t) == LABEL_EXPR)
2629 t = LABEL_EXPR_LABEL (t);
2630 uid = LABEL_DECL_UID (t);
2633 LABEL_DECL_UID (t) = uid = cfun->last_label_uid++;
2634 if (VARRAY_SIZE (label_to_block_map) <= (unsigned) uid)
2635 VARRAY_GROW (label_to_block_map, 3 * uid / 2);
2638 /* We're moving an existing label. Make sure that we've
2639 removed it from the old block. */
2640 gcc_assert (!bb || !VARRAY_BB (label_to_block_map, uid));
2641 VARRAY_BB (label_to_block_map, uid) = bb;
2646 /* Finds iterator for STMT. */
2648 extern block_stmt_iterator
2649 bsi_for_stmt (tree stmt)
2651 block_stmt_iterator bsi;
2653 for (bsi = bsi_start (bb_for_stmt (stmt)); !bsi_end_p (bsi); bsi_next (&bsi))
2654 if (bsi_stmt (bsi) == stmt)
2660 /* Insert statement (or statement list) T before the statement
2661 pointed-to by iterator I. M specifies how to update iterator I
2662 after insertion (see enum bsi_iterator_update). */
2665 bsi_insert_before (block_stmt_iterator *i, tree t, enum bsi_iterator_update m)
2667 set_bb_for_stmt (t, i->bb);
2668 tsi_link_before (&i->tsi, t, m);
2673 /* Insert statement (or statement list) T after the statement
2674 pointed-to by iterator I. M specifies how to update iterator I
2675 after insertion (see enum bsi_iterator_update). */
2678 bsi_insert_after (block_stmt_iterator *i, tree t, enum bsi_iterator_update m)
2680 set_bb_for_stmt (t, i->bb);
2681 tsi_link_after (&i->tsi, t, m);
2686 /* Remove the statement pointed to by iterator I. The iterator is updated
2687 to the next statement. */
2690 bsi_remove (block_stmt_iterator *i)
2692 tree t = bsi_stmt (*i);
2693 set_bb_for_stmt (t, NULL);
2694 tsi_delink (&i->tsi);
2698 /* Move the statement at FROM so it comes right after the statement at TO. */
2701 bsi_move_after (block_stmt_iterator *from, block_stmt_iterator *to)
2703 tree stmt = bsi_stmt (*from);
2705 bsi_insert_after (to, stmt, BSI_SAME_STMT);
2709 /* Move the statement at FROM so it comes right before the statement at TO. */
2712 bsi_move_before (block_stmt_iterator *from, block_stmt_iterator *to)
2714 tree stmt = bsi_stmt (*from);
2716 bsi_insert_before (to, stmt, BSI_SAME_STMT);
2720 /* Move the statement at FROM to the end of basic block BB. */
2723 bsi_move_to_bb_end (block_stmt_iterator *from, basic_block bb)
2725 block_stmt_iterator last = bsi_last (bb);
2727 /* Have to check bsi_end_p because it could be an empty block. */
2728 if (!bsi_end_p (last) && is_ctrl_stmt (bsi_stmt (last)))
2729 bsi_move_before (from, &last);
2731 bsi_move_after (from, &last);
2735 /* Replace the contents of the statement pointed to by iterator BSI
2736 with STMT. If PRESERVE_EH_INFO is true, the exception handling
2737 information of the original statement is preserved. */
2740 bsi_replace (const block_stmt_iterator *bsi, tree stmt, bool preserve_eh_info)
2743 tree orig_stmt = bsi_stmt (*bsi);
2745 SET_EXPR_LOCUS (stmt, EXPR_LOCUS (orig_stmt));
2746 set_bb_for_stmt (stmt, bsi->bb);
2748 /* Preserve EH region information from the original statement, if
2749 requested by the caller. */
2750 if (preserve_eh_info)
2752 eh_region = lookup_stmt_eh_region (orig_stmt);
2754 add_stmt_to_eh_region (stmt, eh_region);
2757 *bsi_stmt_ptr (*bsi) = stmt;
2762 /* Insert the statement pointed-to by BSI into edge E. Every attempt
2763 is made to place the statement in an existing basic block, but
2764 sometimes that isn't possible. When it isn't possible, the edge is
2765 split and the statement is added to the new block.
2767 In all cases, the returned *BSI points to the correct location. The
2768 return value is true if insertion should be done after the location,
2769 or false if it should be done before the location. If new basic block
2770 has to be created, it is stored in *NEW_BB. */
2773 tree_find_edge_insert_loc (edge e, block_stmt_iterator *bsi,
2774 basic_block *new_bb)
2776 basic_block dest, src;
2782 /* If the destination has one predecessor which has no PHI nodes,
2783 insert there. Except for the exit block.
2785 The requirement for no PHI nodes could be relaxed. Basically we
2786 would have to examine the PHIs to prove that none of them used
2787 the value set by the statement we want to insert on E. That
2788 hardly seems worth the effort. */
2789 if (EDGE_COUNT (dest->preds) == 1
2790 && ! phi_nodes (dest)
2791 && dest != EXIT_BLOCK_PTR)
2793 *bsi = bsi_start (dest);
2794 if (bsi_end_p (*bsi))
2797 /* Make sure we insert after any leading labels. */
2798 tmp = bsi_stmt (*bsi);
2799 while (TREE_CODE (tmp) == LABEL_EXPR)
2802 if (bsi_end_p (*bsi))
2804 tmp = bsi_stmt (*bsi);
2807 if (bsi_end_p (*bsi))
2809 *bsi = bsi_last (dest);
2816 /* If the source has one successor, the edge is not abnormal and
2817 the last statement does not end a basic block, insert there.
2818 Except for the entry block. */
2820 if ((e->flags & EDGE_ABNORMAL) == 0
2821 && EDGE_COUNT (src->succs) == 1
2822 && src != ENTRY_BLOCK_PTR)
2824 *bsi = bsi_last (src);
2825 if (bsi_end_p (*bsi))
2828 tmp = bsi_stmt (*bsi);
2829 if (!stmt_ends_bb_p (tmp))
2832 /* Insert code just before returning the value. We may need to decompose
2833 the return in the case it contains non-trivial operand. */
2834 if (TREE_CODE (tmp) == RETURN_EXPR)
2836 tree op = TREE_OPERAND (tmp, 0);
2837 if (!is_gimple_val (op))
2839 gcc_assert (TREE_CODE (op) == MODIFY_EXPR);
2840 bsi_insert_before (bsi, op, BSI_NEW_STMT);
2841 TREE_OPERAND (tmp, 0) = TREE_OPERAND (op, 0);
2848 /* Otherwise, create a new basic block, and split this edge. */
2849 dest = split_edge (e);
2852 e = EDGE_PRED (dest, 0);
2857 /* This routine will commit all pending edge insertions, creating any new
2858 basic blocks which are necessary.
2860 If specified, NEW_BLOCKS returns a count of the number of new basic
2861 blocks which were created. */
2864 bsi_commit_edge_inserts (int *new_blocks)
2871 blocks = n_basic_blocks;
2873 bsi_commit_one_edge_insert (EDGE_SUCC (ENTRY_BLOCK_PTR, 0), NULL);
2876 FOR_EACH_EDGE (e, ei, bb->succs)
2877 bsi_commit_one_edge_insert (e, NULL);
2880 *new_blocks = n_basic_blocks - blocks;
2884 /* Commit insertions pending at edge E. If a new block is created, set NEW_BB
2885 to this block, otherwise set it to NULL. */
2888 bsi_commit_one_edge_insert (edge e, basic_block *new_bb)
2892 if (PENDING_STMT (e))
2894 block_stmt_iterator bsi;
2895 tree stmt = PENDING_STMT (e);
2897 PENDING_STMT (e) = NULL_TREE;
2899 if (tree_find_edge_insert_loc (e, &bsi, new_bb))
2900 bsi_insert_after (&bsi, stmt, BSI_NEW_STMT);
2902 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
2907 /* Add STMT to the pending list of edge E. No actual insertion is
2908 made until a call to bsi_commit_edge_inserts () is made. */
2911 bsi_insert_on_edge (edge e, tree stmt)
2913 append_to_statement_list (stmt, &PENDING_STMT (e));
2916 /* Similar to bsi_insert_on_edge+bsi_commit_edge_inserts. If new block has to
2917 be created, it is returned. */
2920 bsi_insert_on_edge_immediate (edge e, tree stmt)
2922 block_stmt_iterator bsi;
2923 basic_block new_bb = NULL;
2925 gcc_assert (!PENDING_STMT (e));
2927 if (tree_find_edge_insert_loc (e, &bsi, &new_bb))
2928 bsi_insert_after (&bsi, stmt, BSI_NEW_STMT);
2930 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
2935 /*---------------------------------------------------------------------------
2936 Tree specific functions for CFG manipulation
2937 ---------------------------------------------------------------------------*/
2939 /* Split a (typically critical) edge EDGE_IN. Return the new block.
2940 Abort on abnormal edges. */
2943 tree_split_edge (edge edge_in)
2945 basic_block new_bb, after_bb, dest, src;
2951 /* Abnormal edges cannot be split. */
2952 gcc_assert (!(edge_in->flags & EDGE_ABNORMAL));
2955 dest = edge_in->dest;
2957 /* Place the new block in the block list. Try to keep the new block
2958 near its "logical" location. This is of most help to humans looking
2959 at debugging dumps. */
2960 FOR_EACH_EDGE (e, ei, dest->preds)
2961 if (e->src->next_bb == dest)
2964 after_bb = dest->prev_bb;
2966 after_bb = edge_in->src;
2968 new_bb = create_empty_bb (after_bb);
2969 new_bb->frequency = EDGE_FREQUENCY (edge_in);
2970 new_bb->count = edge_in->count;
2971 new_edge = make_edge (new_bb, dest, EDGE_FALLTHRU);
2972 new_edge->probability = REG_BR_PROB_BASE;
2973 new_edge->count = edge_in->count;
2975 /* Find all the PHI arguments on the original edge, and change them to
2976 the new edge. Do it before redirection, so that the argument does not
2978 for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi))
2980 num_elem = PHI_NUM_ARGS (phi);
2981 for (i = 0; i < num_elem; i++)
2982 if (PHI_ARG_EDGE (phi, i) == edge_in)
2984 PHI_ARG_EDGE (phi, i) = new_edge;
2989 e = redirect_edge_and_branch (edge_in, new_bb);
2991 gcc_assert (!PENDING_STMT (edge_in));
2997 /* Return true when BB has label LABEL in it. */
3000 has_label_p (basic_block bb, tree label)
3002 block_stmt_iterator bsi;
3004 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3006 tree stmt = bsi_stmt (bsi);
3008 if (TREE_CODE (stmt) != LABEL_EXPR)
3010 if (LABEL_EXPR_LABEL (stmt) == label)
3017 /* Callback for walk_tree, check that all elements with address taken are
3018 properly noticed as such. */
3021 verify_expr (tree *tp, int *walk_subtrees, void *data ATTRIBUTE_UNUSED)
3028 /* Check operand N for being valid GIMPLE and give error MSG if not.
3029 We check for constants explicitly since they are not considered
3030 gimple invariants if they overflowed. */
3031 #define CHECK_OP(N, MSG) \
3032 do { if (!CONSTANT_CLASS_P (TREE_OPERAND (t, N)) \
3033 && !is_gimple_val (TREE_OPERAND (t, N))) \
3034 { error (MSG); return TREE_OPERAND (t, N); }} while (0)
3036 switch (TREE_CODE (t))
3039 if (SSA_NAME_IN_FREE_LIST (t))
3041 error ("SSA name in freelist but still referenced");
3047 x = TREE_OPERAND (t, 0);
3048 if (TREE_CODE (x) == BIT_FIELD_REF
3049 && is_gimple_reg (TREE_OPERAND (x, 0)))
3051 error ("GIMPLE register modified with BIT_FIELD_REF");
3057 /* Skip any references (they will be checked when we recurse down the
3058 tree) and ensure that any variable used as a prefix is marked
3060 for (x = TREE_OPERAND (t, 0);
3061 (handled_component_p (x)
3062 || TREE_CODE (x) == REALPART_EXPR
3063 || TREE_CODE (x) == IMAGPART_EXPR);
3064 x = TREE_OPERAND (x, 0))
3067 if (TREE_CODE (x) != VAR_DECL && TREE_CODE (x) != PARM_DECL)
3069 if (!TREE_ADDRESSABLE (x))
3071 error ("address taken, but ADDRESSABLE bit not set");
3077 x = TREE_OPERAND (t, 0);
3078 if (TREE_CODE (TREE_TYPE (x)) != BOOLEAN_TYPE)
3080 error ("non-boolean used in condition");
3087 case FIX_TRUNC_EXPR:
3089 case FIX_FLOOR_EXPR:
3090 case FIX_ROUND_EXPR:
3095 case NON_LVALUE_EXPR:
3096 case TRUTH_NOT_EXPR:
3097 CHECK_OP (0, "Invalid operand to unary operator");
3104 case ARRAY_RANGE_REF:
3106 case VIEW_CONVERT_EXPR:
3107 /* We have a nest of references. Verify that each of the operands
3108 that determine where to reference is either a constant or a variable,
3109 verify that the base is valid, and then show we've already checked
3111 while (TREE_CODE (t) == REALPART_EXPR || TREE_CODE (t) == IMAGPART_EXPR
3112 || handled_component_p (t))
3114 if (TREE_CODE (t) == COMPONENT_REF && TREE_OPERAND (t, 2))
3115 CHECK_OP (2, "Invalid COMPONENT_REF offset operator");
3116 else if (TREE_CODE (t) == ARRAY_REF
3117 || TREE_CODE (t) == ARRAY_RANGE_REF)
3119 CHECK_OP (1, "Invalid array index.");
3120 if (TREE_OPERAND (t, 2))
3121 CHECK_OP (2, "Invalid array lower bound.");
3122 if (TREE_OPERAND (t, 3))
3123 CHECK_OP (3, "Invalid array stride.");
3125 else if (TREE_CODE (t) == BIT_FIELD_REF)
3127 CHECK_OP (1, "Invalid operand to BIT_FIELD_REF");
3128 CHECK_OP (2, "Invalid operand to BIT_FIELD_REF");
3131 t = TREE_OPERAND (t, 0);
3134 if (!CONSTANT_CLASS_P (t) && !is_gimple_lvalue (t))
3136 error ("Invalid reference prefix.");
3148 case UNORDERED_EXPR:
3159 case TRUNC_DIV_EXPR:
3161 case FLOOR_DIV_EXPR:
3162 case ROUND_DIV_EXPR:
3163 case TRUNC_MOD_EXPR:
3165 case FLOOR_MOD_EXPR:
3166 case ROUND_MOD_EXPR:
3168 case EXACT_DIV_EXPR:
3178 CHECK_OP (0, "Invalid operand to binary operator");
3179 CHECK_OP (1, "Invalid operand to binary operator");
3191 /* Verify STMT, return true if STMT is not in GIMPLE form.
3192 TODO: Implement type checking. */
3195 verify_stmt (tree stmt, bool last_in_block)
3199 if (!is_gimple_stmt (stmt))
3201 error ("Is not a valid GIMPLE statement.");
3205 addr = walk_tree (&stmt, verify_expr, NULL, NULL);
3208 debug_generic_stmt (addr);
3212 /* If the statement is marked as part of an EH region, then it is
3213 expected that the statement could throw. Verify that when we
3214 have optimizations that simplify statements such that we prove
3215 that they cannot throw, that we update other data structures
3217 if (lookup_stmt_eh_region (stmt) >= 0)
3219 if (!tree_could_throw_p (stmt))
3221 error ("Statement marked for throw, but doesn%'t.");
3224 if (!last_in_block && tree_can_throw_internal (stmt))
3226 error ("Statement marked for throw in middle of block.");
3234 debug_generic_stmt (stmt);
3239 /* Return true when the T can be shared. */
3242 tree_node_can_be_shared (tree t)
3244 if (IS_TYPE_OR_DECL_P (t)
3245 /* We check for constants explicitly since they are not considered
3246 gimple invariants if they overflowed. */
3247 || CONSTANT_CLASS_P (t)
3248 || is_gimple_min_invariant (t)
3249 || TREE_CODE (t) == SSA_NAME)
3252 while (((TREE_CODE (t) == ARRAY_REF || TREE_CODE (t) == ARRAY_RANGE_REF)
3253 /* We check for constants explicitly since they are not considered
3254 gimple invariants if they overflowed. */
3255 && (CONSTANT_CLASS_P (TREE_OPERAND (t, 1))
3256 || is_gimple_min_invariant (TREE_OPERAND (t, 1))))
3257 || (TREE_CODE (t) == COMPONENT_REF
3258 || TREE_CODE (t) == REALPART_EXPR
3259 || TREE_CODE (t) == IMAGPART_EXPR))
3260 t = TREE_OPERAND (t, 0);
3269 /* Called via walk_trees. Verify tree sharing. */
3272 verify_node_sharing (tree * tp, int *walk_subtrees, void *data)
3274 htab_t htab = (htab_t) data;
3277 if (tree_node_can_be_shared (*tp))
3279 *walk_subtrees = false;
3283 slot = htab_find_slot (htab, *tp, INSERT);
3292 /* Verify the GIMPLE statement chain. */
3298 block_stmt_iterator bsi;
3303 timevar_push (TV_TREE_STMT_VERIFY);
3304 htab = htab_create (37, htab_hash_pointer, htab_eq_pointer, NULL);
3311 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
3313 int phi_num_args = PHI_NUM_ARGS (phi);
3315 for (i = 0; i < phi_num_args; i++)
3317 tree t = PHI_ARG_DEF (phi, i);
3320 /* Addressable variables do have SSA_NAMEs but they
3321 are not considered gimple values. */
3322 if (TREE_CODE (t) != SSA_NAME
3323 && TREE_CODE (t) != FUNCTION_DECL
3324 && !is_gimple_val (t))
3326 error ("PHI def is not a GIMPLE value");
3327 debug_generic_stmt (phi);
3328 debug_generic_stmt (t);
3332 addr = walk_tree (&t, verify_expr, NULL, NULL);
3335 debug_generic_stmt (addr);
3339 addr = walk_tree (&t, verify_node_sharing, htab, NULL);
3342 error ("Incorrect sharing of tree nodes");
3343 debug_generic_stmt (phi);
3344 debug_generic_stmt (addr);
3350 for (bsi = bsi_start (bb); !bsi_end_p (bsi); )
3352 tree stmt = bsi_stmt (bsi);
3354 err |= verify_stmt (stmt, bsi_end_p (bsi));
3355 addr = walk_tree (&stmt, verify_node_sharing, htab, NULL);
3358 error ("Incorrect sharing of tree nodes");
3359 debug_generic_stmt (stmt);
3360 debug_generic_stmt (addr);
3367 internal_error ("verify_stmts failed.");
3370 timevar_pop (TV_TREE_STMT_VERIFY);
3374 /* Verifies that the flow information is OK. */
3377 tree_verify_flow_info (void)
3381 block_stmt_iterator bsi;
3386 if (ENTRY_BLOCK_PTR->stmt_list)
3388 error ("ENTRY_BLOCK has a statement list associated with it\n");
3392 if (EXIT_BLOCK_PTR->stmt_list)
3394 error ("EXIT_BLOCK has a statement list associated with it\n");
3398 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
3399 if (e->flags & EDGE_FALLTHRU)
3401 error ("Fallthru to exit from bb %d\n", e->src->index);
3407 bool found_ctrl_stmt = false;
3409 /* Skip labels on the start of basic block. */
3410 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3412 if (TREE_CODE (bsi_stmt (bsi)) != LABEL_EXPR)
3415 if (label_to_block (LABEL_EXPR_LABEL (bsi_stmt (bsi))) != bb)
3417 tree stmt = bsi_stmt (bsi);
3418 error ("Label %s to block does not match in bb %d\n",
3419 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt))),
3424 if (decl_function_context (LABEL_EXPR_LABEL (bsi_stmt (bsi)))
3425 != current_function_decl)
3427 tree stmt = bsi_stmt (bsi);
3428 error ("Label %s has incorrect context in bb %d\n",
3429 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt))),
3435 /* Verify that body of basic block BB is free of control flow. */
3436 for (; !bsi_end_p (bsi); bsi_next (&bsi))
3438 tree stmt = bsi_stmt (bsi);
3440 if (found_ctrl_stmt)
3442 error ("Control flow in the middle of basic block %d\n",
3447 if (stmt_ends_bb_p (stmt))
3448 found_ctrl_stmt = true;
3450 if (TREE_CODE (stmt) == LABEL_EXPR)
3452 error ("Label %s in the middle of basic block %d\n",
3453 IDENTIFIER_POINTER (DECL_NAME (stmt)),
3458 bsi = bsi_last (bb);
3459 if (bsi_end_p (bsi))
3462 stmt = bsi_stmt (bsi);
3464 if (is_ctrl_stmt (stmt))
3466 FOR_EACH_EDGE (e, ei, bb->succs)
3467 if (e->flags & EDGE_FALLTHRU)
3469 error ("Fallthru edge after a control statement in bb %d \n",
3475 switch (TREE_CODE (stmt))
3481 if (TREE_CODE (COND_EXPR_THEN (stmt)) != GOTO_EXPR
3482 || TREE_CODE (COND_EXPR_ELSE (stmt)) != GOTO_EXPR)
3484 error ("Structured COND_EXPR at the end of bb %d\n", bb->index);
3488 extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
3490 if (!true_edge || !false_edge
3491 || !(true_edge->flags & EDGE_TRUE_VALUE)
3492 || !(false_edge->flags & EDGE_FALSE_VALUE)
3493 || (true_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL))
3494 || (false_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL))
3495 || EDGE_COUNT (bb->succs) >= 3)
3497 error ("Wrong outgoing edge flags at end of bb %d\n",
3502 if (!has_label_p (true_edge->dest,
3503 GOTO_DESTINATION (COND_EXPR_THEN (stmt))))
3505 error ("%<then%> label does not match edge at end of bb %d\n",
3510 if (!has_label_p (false_edge->dest,
3511 GOTO_DESTINATION (COND_EXPR_ELSE (stmt))))
3513 error ("%<else%> label does not match edge at end of bb %d\n",
3521 if (simple_goto_p (stmt))
3523 error ("Explicit goto at end of bb %d\n", bb->index);
3528 /* FIXME. We should double check that the labels in the
3529 destination blocks have their address taken. */
3530 FOR_EACH_EDGE (e, ei, bb->succs)
3531 if ((e->flags & (EDGE_FALLTHRU | EDGE_TRUE_VALUE
3532 | EDGE_FALSE_VALUE))
3533 || !(e->flags & EDGE_ABNORMAL))
3535 error ("Wrong outgoing edge flags at end of bb %d\n",
3543 if (EDGE_COUNT (bb->succs) != 1
3544 || (EDGE_SUCC (bb, 0)->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL
3545 | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
3547 error ("Wrong outgoing edge flags at end of bb %d\n", bb->index);
3550 if (EDGE_SUCC (bb, 0)->dest != EXIT_BLOCK_PTR)
3552 error ("Return edge does not point to exit in bb %d\n",
3565 vec = SWITCH_LABELS (stmt);
3566 n = TREE_VEC_LENGTH (vec);
3568 /* Mark all the destination basic blocks. */
3569 for (i = 0; i < n; ++i)
3571 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
3572 basic_block label_bb = label_to_block (lab);
3574 gcc_assert (!label_bb->aux || label_bb->aux == (void *)1);
3575 label_bb->aux = (void *)1;
3578 /* Verify that the case labels are sorted. */
3579 prev = TREE_VEC_ELT (vec, 0);
3580 for (i = 1; i < n - 1; ++i)
3582 tree c = TREE_VEC_ELT (vec, i);
3585 error ("Found default case not at end of case vector");
3589 if (! tree_int_cst_lt (CASE_LOW (prev), CASE_LOW (c)))
3591 error ("Case labels not sorted:\n ");
3592 print_generic_expr (stderr, prev, 0);
3593 fprintf (stderr," is greater than ");
3594 print_generic_expr (stderr, c, 0);
3595 fprintf (stderr," but comes before it.\n");
3600 if (CASE_LOW (TREE_VEC_ELT (vec, n - 1)))
3602 error ("No default case found at end of case vector");
3606 FOR_EACH_EDGE (e, ei, bb->succs)
3610 error ("Extra outgoing edge %d->%d\n",
3611 bb->index, e->dest->index);
3614 e->dest->aux = (void *)2;
3615 if ((e->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL
3616 | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
3618 error ("Wrong outgoing edge flags at end of bb %d\n",
3624 /* Check that we have all of them. */
3625 for (i = 0; i < n; ++i)
3627 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
3628 basic_block label_bb = label_to_block (lab);
3630 if (label_bb->aux != (void *)2)
3632 error ("Missing edge %i->%i\n",
3633 bb->index, label_bb->index);
3638 FOR_EACH_EDGE (e, ei, bb->succs)
3639 e->dest->aux = (void *)0;
3646 if (dom_computed[CDI_DOMINATORS] >= DOM_NO_FAST_QUERY)
3647 verify_dominators (CDI_DOMINATORS);
3653 /* Updates phi nodes after creating a forwarder block joined
3654 by edge FALLTHRU. */
3657 tree_make_forwarder_block (edge fallthru)
3661 basic_block dummy, bb;
3662 tree phi, new_phi, var, prev, next;
3664 dummy = fallthru->src;
3665 bb = fallthru->dest;
3667 if (EDGE_COUNT (bb->preds) == 1)
3670 /* If we redirected a branch we must create new phi nodes at the
3672 for (phi = phi_nodes (dummy); phi; phi = PHI_CHAIN (phi))
3674 var = PHI_RESULT (phi);
3675 new_phi = create_phi_node (var, bb);
3676 SSA_NAME_DEF_STMT (var) = new_phi;
3677 SET_PHI_RESULT (phi, make_ssa_name (SSA_NAME_VAR (var), phi));
3678 add_phi_arg (&new_phi, PHI_RESULT (phi), fallthru);
3681 /* Ensure that the PHI node chain is in the same order. */
3683 for (phi = phi_nodes (bb); phi; phi = next)
3685 next = PHI_CHAIN (phi);
3686 PHI_CHAIN (phi) = prev;
3689 set_phi_nodes (bb, prev);
3691 /* Add the arguments we have stored on edges. */
3692 FOR_EACH_EDGE (e, ei, bb->preds)
3697 flush_pending_stmts (e);
3702 /* Return true if basic block BB does nothing except pass control
3703 flow to another block and that we can safely insert a label at
3704 the start of the successor block.
3706 As a precondition, we require that BB be not equal to
3710 tree_forwarder_block_p (basic_block bb)
3712 block_stmt_iterator bsi;
3716 /* BB must have a single outgoing edge. */
3717 if (EDGE_COUNT (bb->succs) != 1
3718 /* BB can not have any PHI nodes. This could potentially be
3719 relaxed early in compilation if we re-rewrote the variables
3720 appearing in any PHI nodes in forwarder blocks. */
3722 /* BB may not be a predecessor of EXIT_BLOCK_PTR. */
3723 || EDGE_SUCC (bb, 0)->dest == EXIT_BLOCK_PTR
3724 /* BB may not have an abnormal outgoing edge. */
3725 || (EDGE_SUCC (bb, 0)->flags & EDGE_ABNORMAL))
3729 gcc_assert (bb != ENTRY_BLOCK_PTR);
3732 /* Successors of the entry block are not forwarders. */
3733 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
3737 /* Now walk through the statements. We can ignore labels, anything else
3738 means this is not a forwarder block. */
3739 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3741 tree stmt = bsi_stmt (bsi);
3743 switch (TREE_CODE (stmt))
3746 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)))
3758 /* Thread jumps from BB. */
3761 thread_jumps_from_bb (basic_block bb)
3765 bool retval = false;
3767 /* Examine each of our block's successors to see if it is
3769 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
3774 basic_block dest, tmp, curr, old_dest;
3778 /* If the edge is abnormal or its destination is not
3779 forwardable, then there's nothing to do. */
3780 if ((e->flags & EDGE_ABNORMAL)
3781 || !bb_ann (e->dest)->forwardable)
3787 /* Now walk through as many forwarder blocks as possible to find
3788 the ultimate destination we want to thread our jump to. */
3789 last = EDGE_SUCC (e->dest, 0);
3790 bb_ann (e->dest)->forwardable = 0;
3791 for (dest = EDGE_SUCC (e->dest, 0)->dest;
3792 bb_ann (dest)->forwardable;
3793 last = EDGE_SUCC (dest, 0),
3794 dest = EDGE_SUCC (dest, 0)->dest)
3795 bb_ann (dest)->forwardable = 0;
3797 /* Reset the forwardable marks to 1. */
3800 tmp = EDGE_SUCC (tmp, 0)->dest)
3801 bb_ann (tmp)->forwardable = 1;
3803 if (dest == e->dest)
3809 old = find_edge (bb, dest);
3812 /* If there already is an edge, check whether the values in
3813 phi nodes differ. */
3814 if (!phi_alternatives_equal (dest, last, old))
3816 /* The previous block is forwarder. Redirect our jump
3817 to that target instead since we know it has no PHI
3818 nodes that will need updating. */
3821 /* That might mean that no forwarding at all is
3823 if (dest == e->dest)
3829 old = find_edge (bb, dest);
3833 /* Perform the redirection. */
3836 freq = EDGE_FREQUENCY (e);
3838 e = redirect_edge_and_branch (e, dest);
3840 /* Update the profile. */
3841 if (profile_status != PROFILE_ABSENT)
3842 for (curr = old_dest;
3844 curr = EDGE_SUCC (curr, 0)->dest)
3846 curr->frequency -= freq;
3847 if (curr->frequency < 0)
3848 curr->frequency = 0;
3849 curr->count -= count;
3850 if (curr->count < 0)
3852 EDGE_SUCC (curr, 0)->count -= count;
3853 if (EDGE_SUCC (curr, 0)->count < 0)
3854 EDGE_SUCC (curr, 0)->count = 0;
3859 /* Update PHI nodes. We know that the new argument should
3860 have the same value as the argument associated with LAST.
3861 Otherwise we would have changed our target block
3863 for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi))
3865 arg = phi_arg_from_edge (phi, last);
3866 gcc_assert (arg >= 0);
3867 add_phi_arg (&phi, PHI_ARG_DEF (phi, arg), e);
3871 /* Remove the unreachable blocks (observe that if all blocks
3872 were reachable before, only those in the path we threaded
3873 over and did not have any predecessor outside of the path
3874 become unreachable). */
3875 for (; old_dest != dest; old_dest = tmp)
3877 tmp = EDGE_SUCC (old_dest, 0)->dest;
3879 if (EDGE_COUNT (old_dest->preds) > 0)
3882 delete_basic_block (old_dest);
3885 /* Update the dominators. */
3886 if (dom_info_available_p (CDI_DOMINATORS))
3888 /* If the dominator of the destination was in the
3889 path, set its dominator to the start of the
3891 if (get_immediate_dominator (CDI_DOMINATORS, old_dest) == NULL)
3892 set_immediate_dominator (CDI_DOMINATORS, old_dest, bb);
3894 /* Now proceed like if we forwarded just over one edge at a
3895 time. Algorithm for forwarding edge S --> A over
3896 edge A --> B then is
3899 && !dominated_by (S, B))
3900 idom (B) = idom (A);
3901 recount_idom (A); */
3903 for (; old_dest != dest; old_dest = tmp)
3907 tmp = EDGE_SUCC (old_dest, 0)->dest;
3909 if (get_immediate_dominator (CDI_DOMINATORS, tmp) == old_dest
3910 && !dominated_by_p (CDI_DOMINATORS, bb, tmp))
3912 dom = get_immediate_dominator (CDI_DOMINATORS, old_dest);
3913 set_immediate_dominator (CDI_DOMINATORS, tmp, dom);
3916 dom = recount_dominator (CDI_DOMINATORS, old_dest);
3917 set_immediate_dominator (CDI_DOMINATORS, old_dest, dom);
3926 /* Thread jumps over empty statements.
3928 This code should _not_ thread over obviously equivalent conditions
3929 as that requires nontrivial updates to the SSA graph.
3931 As a precondition, we require that all basic blocks be reachable.
3932 That is, there should be no opportunities left for
3933 delete_unreachable_blocks. */
3939 bool retval = false;
3940 basic_block *worklist = xmalloc (sizeof (basic_block) * last_basic_block);
3941 unsigned int size = 0;
3945 bb_ann (bb)->forwardable = tree_forwarder_block_p (bb);
3946 bb->flags &= ~BB_VISITED;
3949 /* We pretend to have ENTRY_BLOCK_PTR in WORKLIST. This way,
3950 ENTRY_BLOCK_PTR will never be entered into WORKLIST. */
3951 ENTRY_BLOCK_PTR->flags |= BB_VISITED;
3953 /* Initialize WORKLIST by putting non-forwarder blocks that
3954 immediately precede forwarder blocks because those are the ones
3955 that we know we can thread jumps from. We use BB_VISITED to
3956 indicate whether a given basic block is in WORKLIST or not,
3957 thereby avoiding duplicates in WORKLIST. */
3963 /* We are not interested in finding non-forwarder blocks
3964 directly. We want to find non-forwarder blocks as
3965 predecessors of a forwarder block. */
3966 if (!bb_ann (bb)->forwardable)
3969 /* Now we know BB is a forwarder block. Visit each of its
3970 incoming edges and add to WORKLIST all non-forwarder blocks
3971 among BB's predecessors. */
3972 FOR_EACH_EDGE (e, ei, bb->preds)
3974 /* We don't want to put a duplicate into WORKLIST. */
3975 if ((e->src->flags & BB_VISITED) == 0
3976 /* We are not interested in threading jumps from a forwarder
3978 && !bb_ann (e->src)->forwardable)
3980 e->src->flags |= BB_VISITED;
3981 worklist[size] = e->src;
3987 /* Now let's drain WORKLIST. */
3991 bb = worklist[size];
3993 /* BB is no longer in WORKLIST, so clear BB_VISITED. */
3994 bb->flags &= ~BB_VISITED;
3996 if (thread_jumps_from_bb (bb))
4000 if (tree_forwarder_block_p (bb))
4005 bb_ann (bb)->forwardable = true;
4007 /* Attempts to thread through BB may have been blocked
4008 because BB was not a forwarder block before. Now
4009 that BB is a forwarder block, we should revisit BB's
4011 FOR_EACH_EDGE (f, ej, bb->preds)
4013 /* We don't want to put a duplicate into WORKLIST. */
4014 if ((f->src->flags & BB_VISITED) == 0
4015 /* We are not interested in threading jumps from a
4017 && !bb_ann (f->src)->forwardable)
4019 f->src->flags |= BB_VISITED;
4020 worklist[size] = f->src;
4028 ENTRY_BLOCK_PTR->flags &= ~BB_VISITED;
4036 /* Return a non-special label in the head of basic block BLOCK.
4037 Create one if it doesn't exist. */
4040 tree_block_label (basic_block bb)
4042 block_stmt_iterator i, s = bsi_start (bb);
4046 for (i = s; !bsi_end_p (i); first = false, bsi_next (&i))
4048 stmt = bsi_stmt (i);
4049 if (TREE_CODE (stmt) != LABEL_EXPR)
4051 label = LABEL_EXPR_LABEL (stmt);
4052 if (!DECL_NONLOCAL (label))
4055 bsi_move_before (&i, &s);
4060 label = create_artificial_label ();
4061 stmt = build1 (LABEL_EXPR, void_type_node, label);
4062 bsi_insert_before (&s, stmt, BSI_NEW_STMT);
4067 /* Attempt to perform edge redirection by replacing a possibly complex
4068 jump instruction by a goto or by removing the jump completely.
4069 This can apply only if all edges now point to the same block. The
4070 parameters and return values are equivalent to
4071 redirect_edge_and_branch. */
4074 tree_try_redirect_by_replacing_jump (edge e, basic_block target)
4076 basic_block src = e->src;
4078 block_stmt_iterator b;
4082 /* Verify that all targets will be TARGET. */
4083 FOR_EACH_EDGE (tmp, ei, src->succs)
4084 if (tmp->dest != target && tmp != e)
4093 stmt = bsi_stmt (b);
4095 if (TREE_CODE (stmt) == COND_EXPR
4096 || TREE_CODE (stmt) == SWITCH_EXPR)
4099 e = ssa_redirect_edge (e, target);
4100 e->flags = EDGE_FALLTHRU;
4108 /* Redirect E to DEST. Return NULL on failure. Otherwise, return the
4109 edge representing the redirected branch. */
4112 tree_redirect_edge_and_branch (edge e, basic_block dest)
4114 basic_block bb = e->src;
4115 block_stmt_iterator bsi;
4119 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
4122 if (e->src != ENTRY_BLOCK_PTR
4123 && (ret = tree_try_redirect_by_replacing_jump (e, dest)))
4126 if (e->dest == dest)
4129 label = tree_block_label (dest);
4131 bsi = bsi_last (bb);
4132 stmt = bsi_end_p (bsi) ? NULL : bsi_stmt (bsi);
4134 switch (stmt ? TREE_CODE (stmt) : ERROR_MARK)
4137 stmt = (e->flags & EDGE_TRUE_VALUE
4138 ? COND_EXPR_THEN (stmt)
4139 : COND_EXPR_ELSE (stmt));
4140 GOTO_DESTINATION (stmt) = label;
4144 /* No non-abnormal edges should lead from a non-simple goto, and
4145 simple ones should be represented implicitly. */
4150 tree vec = SWITCH_LABELS (stmt);
4151 size_t i, n = TREE_VEC_LENGTH (vec);
4153 for (i = 0; i < n; ++i)
4155 tree elt = TREE_VEC_ELT (vec, i);
4156 if (label_to_block (CASE_LABEL (elt)) == e->dest)
4157 CASE_LABEL (elt) = label;
4164 e->flags |= EDGE_FALLTHRU;
4168 /* Otherwise it must be a fallthru edge, and we don't need to
4169 do anything besides redirecting it. */
4170 gcc_assert (e->flags & EDGE_FALLTHRU);
4174 /* Update/insert PHI nodes as necessary. */
4176 /* Now update the edges in the CFG. */
4177 e = ssa_redirect_edge (e, dest);
4183 /* Simple wrapper, as we can always redirect fallthru edges. */
4186 tree_redirect_edge_and_branch_force (edge e, basic_block dest)
4188 e = tree_redirect_edge_and_branch (e, dest);
4195 /* Splits basic block BB after statement STMT (but at least after the
4196 labels). If STMT is NULL, BB is split just after the labels. */
4199 tree_split_block (basic_block bb, void *stmt)
4201 block_stmt_iterator bsi, bsi_tgt;
4207 new_bb = create_empty_bb (bb);
4209 /* Redirect the outgoing edges. */
4210 new_bb->succs = bb->succs;
4212 FOR_EACH_EDGE (e, ei, new_bb->succs)
4215 if (stmt && TREE_CODE ((tree) stmt) == LABEL_EXPR)
4218 /* Move everything from BSI to the new basic block. */
4219 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4221 act = bsi_stmt (bsi);
4222 if (TREE_CODE (act) == LABEL_EXPR)
4235 bsi_tgt = bsi_start (new_bb);
4236 while (!bsi_end_p (bsi))
4238 act = bsi_stmt (bsi);
4240 bsi_insert_after (&bsi_tgt, act, BSI_NEW_STMT);
4247 /* Moves basic block BB after block AFTER. */
4250 tree_move_block_after (basic_block bb, basic_block after)
4252 if (bb->prev_bb == after)
4256 link_block (bb, after);
4262 /* Return true if basic_block can be duplicated. */
4265 tree_can_duplicate_bb_p (basic_block bb ATTRIBUTE_UNUSED)
4270 /* Create a duplicate of the basic block BB. NOTE: This does not
4271 preserve SSA form. */
4274 tree_duplicate_bb (basic_block bb)
4277 block_stmt_iterator bsi, bsi_tgt;
4279 ssa_op_iter op_iter;
4281 new_bb = create_empty_bb (EXIT_BLOCK_PTR->prev_bb);
4283 /* First copy the phi nodes. We do not copy phi node arguments here,
4284 since the edges are not ready yet. Keep the chain of phi nodes in
4285 the same order, so that we can add them later. */
4286 for (phi = phi_nodes (bb); phi; phi = TREE_CHAIN (phi))
4288 mark_for_rewrite (PHI_RESULT (phi));
4289 create_phi_node (PHI_RESULT (phi), new_bb);
4291 set_phi_nodes (new_bb, nreverse (phi_nodes (new_bb)));
4293 bsi_tgt = bsi_start (new_bb);
4294 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4296 tree stmt = bsi_stmt (bsi);
4299 if (TREE_CODE (stmt) == LABEL_EXPR)
4302 /* Record the definitions. */
4303 get_stmt_operands (stmt);
4305 FOR_EACH_SSA_TREE_OPERAND (val, stmt, op_iter, SSA_OP_ALL_DEFS)
4306 mark_for_rewrite (val);
4308 copy = unshare_expr (stmt);
4310 /* Copy also the virtual operands. */
4311 get_stmt_ann (copy);
4312 copy_virtual_operands (copy, stmt);
4314 bsi_insert_after (&bsi_tgt, copy, BSI_NEW_STMT);
4320 /* Basic block BB_COPY was created by code duplication. Add phi node
4321 arguments for edges going out of BB_COPY. The blocks that were
4322 duplicated have rbi->duplicated set to one. */
4325 add_phi_args_after_copy_bb (basic_block bb_copy)
4327 basic_block bb, dest;
4330 tree phi, phi_copy, phi_next, def;
4332 bb = bb_copy->rbi->original;
4334 FOR_EACH_EDGE (e_copy, ei, bb_copy->succs)
4336 if (!phi_nodes (e_copy->dest))
4339 if (e_copy->dest->rbi->duplicated)
4340 dest = e_copy->dest->rbi->original;
4342 dest = e_copy->dest;
4344 e = find_edge (bb, dest);
4347 /* During loop unrolling the target of the latch edge is copied.
4348 In this case we are not looking for edge to dest, but to
4349 duplicated block whose original was dest. */
4350 FOR_EACH_EDGE (e, ei, bb->succs)
4351 if (e->dest->rbi->duplicated
4352 && e->dest->rbi->original == dest)
4355 gcc_assert (e != NULL);
4358 for (phi = phi_nodes (e->dest), phi_copy = phi_nodes (e_copy->dest);
4360 phi = phi_next, phi_copy = TREE_CHAIN (phi_copy))
4362 phi_next = TREE_CHAIN (phi);
4364 gcc_assert (PHI_RESULT (phi) == PHI_RESULT (phi_copy));
4365 def = PHI_ARG_DEF_FROM_EDGE (phi, e);
4366 add_phi_arg (&phi_copy, def, e_copy);
4371 /* Blocks in REGION_COPY array of length N_REGION were created by
4372 duplication of basic blocks. Add phi node arguments for edges
4373 going from these blocks. */
4376 add_phi_args_after_copy (basic_block *region_copy, unsigned n_region)
4380 for (i = 0; i < n_region; i++)
4381 region_copy[i]->rbi->duplicated = 1;
4383 for (i = 0; i < n_region; i++)
4384 add_phi_args_after_copy_bb (region_copy[i]);
4386 for (i = 0; i < n_region; i++)
4387 region_copy[i]->rbi->duplicated = 0;
4390 /* Maps the old ssa name FROM_NAME to TO_NAME. */
4392 struct ssa_name_map_entry
4398 /* Hash function for ssa_name_map_entry. */
4401 ssa_name_map_entry_hash (const void *entry)
4403 const struct ssa_name_map_entry *en = entry;
4404 return SSA_NAME_VERSION (en->from_name);
4407 /* Equality function for ssa_name_map_entry. */
4410 ssa_name_map_entry_eq (const void *in_table, const void *ssa_name)
4412 const struct ssa_name_map_entry *en = in_table;
4414 return en->from_name == ssa_name;
4417 /* Allocate duplicates of ssa names in list DEFINITIONS and store the mapping
4421 allocate_ssa_names (bitmap definitions, htab_t *map)
4424 struct ssa_name_map_entry *entry;
4430 *map = htab_create (10, ssa_name_map_entry_hash,
4431 ssa_name_map_entry_eq, free);
4432 EXECUTE_IF_SET_IN_BITMAP (definitions, 0, ver, bi)
4434 name = ssa_name (ver);
4435 slot = htab_find_slot_with_hash (*map, name, SSA_NAME_VERSION (name),
4441 entry = xmalloc (sizeof (struct ssa_name_map_entry));
4442 entry->from_name = name;
4445 entry->to_name = duplicate_ssa_name (name, SSA_NAME_DEF_STMT (name));
4449 /* Rewrite the definition DEF in statement STMT to new ssa name as specified
4450 by the mapping MAP. */
4453 rewrite_to_new_ssa_names_def (def_operand_p def, tree stmt, htab_t map)
4455 tree name = DEF_FROM_PTR (def);
4456 struct ssa_name_map_entry *entry;
4458 gcc_assert (TREE_CODE (name) == SSA_NAME);
4460 entry = htab_find_with_hash (map, name, SSA_NAME_VERSION (name));
4464 SET_DEF (def, entry->to_name);
4465 SSA_NAME_DEF_STMT (entry->to_name) = stmt;
4468 /* Rewrite the USE to new ssa name as specified by the mapping MAP. */
4471 rewrite_to_new_ssa_names_use (use_operand_p use, htab_t map)
4473 tree name = USE_FROM_PTR (use);
4474 struct ssa_name_map_entry *entry;
4476 if (TREE_CODE (name) != SSA_NAME)
4479 entry = htab_find_with_hash (map, name, SSA_NAME_VERSION (name));
4483 SET_USE (use, entry->to_name);
4486 /* Rewrite the ssa names in basic block BB to new ones as specified by the
4490 rewrite_to_new_ssa_names_bb (basic_block bb, htab_t map)
4496 block_stmt_iterator bsi;
4500 v_may_def_optype v_may_defs;
4501 v_must_def_optype v_must_defs;
4504 FOR_EACH_EDGE (e, ei, bb->preds)
4505 if (e->flags & EDGE_ABNORMAL)
4508 for (phi = phi_nodes (bb); phi; phi = TREE_CHAIN (phi))
4510 rewrite_to_new_ssa_names_def (PHI_RESULT_PTR (phi), phi, map);
4512 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (PHI_RESULT (phi)) = 1;
4515 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4517 stmt = bsi_stmt (bsi);
4518 get_stmt_operands (stmt);
4519 ann = stmt_ann (stmt);
4521 uses = USE_OPS (ann);
4522 for (i = 0; i < NUM_USES (uses); i++)
4523 rewrite_to_new_ssa_names_use (USE_OP_PTR (uses, i), map);
4525 defs = DEF_OPS (ann);
4526 for (i = 0; i < NUM_DEFS (defs); i++)
4527 rewrite_to_new_ssa_names_def (DEF_OP_PTR (defs, i), stmt, map);
4529 vuses = VUSE_OPS (ann);
4530 for (i = 0; i < NUM_VUSES (vuses); i++)
4531 rewrite_to_new_ssa_names_use (VUSE_OP_PTR (vuses, i), map);
4533 v_may_defs = V_MAY_DEF_OPS (ann);
4534 for (i = 0; i < NUM_V_MAY_DEFS (v_may_defs); i++)
4536 rewrite_to_new_ssa_names_use
4537 (V_MAY_DEF_OP_PTR (v_may_defs, i), map);
4538 rewrite_to_new_ssa_names_def
4539 (V_MAY_DEF_RESULT_PTR (v_may_defs, i), stmt, map);
4542 v_must_defs = V_MUST_DEF_OPS (ann);
4543 for (i = 0; i < NUM_V_MUST_DEFS (v_must_defs); i++)
4545 rewrite_to_new_ssa_names_def
4546 (V_MUST_DEF_RESULT_PTR (v_must_defs, i), stmt, map);
4547 rewrite_to_new_ssa_names_use
4548 (V_MUST_DEF_KILL_PTR (v_must_defs, i), map);
4552 FOR_EACH_EDGE (e, ei, bb->succs)
4553 for (phi = phi_nodes (e->dest); phi; phi = TREE_CHAIN (phi))
4555 rewrite_to_new_ssa_names_use
4556 (PHI_ARG_DEF_PTR_FROM_EDGE (phi, e), map);
4558 if (e->flags & EDGE_ABNORMAL)
4560 tree op = PHI_ARG_DEF_FROM_EDGE (phi, e);
4561 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op) = 1;
4566 /* Rewrite the ssa names in N_REGION blocks REGION to the new ones as specified
4567 by the mapping MAP. */
4570 rewrite_to_new_ssa_names (basic_block *region, unsigned n_region, htab_t map)
4574 for (r = 0; r < n_region; r++)
4575 rewrite_to_new_ssa_names_bb (region[r], map);
4578 /* Duplicates a REGION (set of N_REGION basic blocks) with just a single
4579 important exit edge EXIT. By important we mean that no SSA name defined
4580 inside region is live over the other exit edges of the region. All entry
4581 edges to the region must go to ENTRY->dest. The edge ENTRY is redirected
4582 to the duplicate of the region. SSA form, dominance and loop information
4583 is updated. The new basic blocks are stored to REGION_COPY in the same
4584 order as they had in REGION, provided that REGION_COPY is not NULL.
4585 The function returns false if it is unable to copy the region,
4589 tree_duplicate_sese_region (edge entry, edge exit,
4590 basic_block *region, unsigned n_region,
4591 basic_block *region_copy)
4593 unsigned i, n_doms, ver;
4594 bool free_region_copy = false, copying_header = false;
4595 struct loop *loop = entry->dest->loop_father;
4600 htab_t ssa_name_map = NULL;
4604 if (!can_copy_bbs_p (region, n_region))
4607 /* Some sanity checking. Note that we do not check for all possible
4608 missuses of the functions. I.e. if you ask to copy something weird,
4609 it will work, but the state of structures probably will not be
4612 for (i = 0; i < n_region; i++)
4614 /* We do not handle subloops, i.e. all the blocks must belong to the
4616 if (region[i]->loop_father != loop)
4619 if (region[i] != entry->dest
4620 && region[i] == loop->header)
4626 /* In case the function is used for loop header copying (which is the primary
4627 use), ensure that EXIT and its copy will be new latch and entry edges. */
4628 if (loop->header == entry->dest)
4630 copying_header = true;
4631 loop->copy = loop->outer;
4633 if (!dominated_by_p (CDI_DOMINATORS, loop->latch, exit->src))
4636 for (i = 0; i < n_region; i++)
4637 if (region[i] != exit->src
4638 && dominated_by_p (CDI_DOMINATORS, region[i], exit->src))
4644 region_copy = xmalloc (sizeof (basic_block) * n_region);
4645 free_region_copy = true;
4648 gcc_assert (!any_marked_for_rewrite_p ());
4650 /* Record blocks outside the region that are duplicated by something
4652 doms = xmalloc (sizeof (basic_block) * n_basic_blocks);
4653 n_doms = get_dominated_by_region (CDI_DOMINATORS, region, n_region, doms);
4655 copy_bbs (region, n_region, region_copy, &exit, 1, &exit_copy, loop);
4656 definitions = marked_ssa_names ();
4660 loop->header = exit->dest;
4661 loop->latch = exit->src;
4664 /* Redirect the entry and add the phi node arguments. */
4665 redirected = redirect_edge_and_branch (entry, entry->dest->rbi->copy);
4666 gcc_assert (redirected != NULL);
4667 flush_pending_stmts (entry);
4669 /* Concerning updating of dominators: We must recount dominators
4670 for entry block and its copy. Anything that is outside of the region, but
4671 was dominated by something inside needs recounting as well. */
4672 set_immediate_dominator (CDI_DOMINATORS, entry->dest, entry->src);
4673 doms[n_doms++] = entry->dest->rbi->original;
4674 iterate_fix_dominators (CDI_DOMINATORS, doms, n_doms);
4677 /* Add the other phi node arguments. */
4678 add_phi_args_after_copy (region_copy, n_region);
4680 /* Add phi nodes for definitions at exit. TODO -- once we have immediate
4681 uses, it should be possible to emit phi nodes just for definitions that
4682 are used outside region. */
4683 EXECUTE_IF_SET_IN_BITMAP (definitions, 0, ver, bi)
4685 tree name = ssa_name (ver);
4687 phi = create_phi_node (name, exit->dest);
4688 add_phi_arg (&phi, name, exit);
4689 add_phi_arg (&phi, name, exit_copy);
4691 SSA_NAME_DEF_STMT (name) = phi;
4694 /* And create new definitions inside region and its copy. TODO -- once we
4695 have immediate uses, it might be better to leave definitions in region
4696 unchanged, create new ssa names for phi nodes on exit, and rewrite
4697 the uses, to avoid changing the copied region. */
4698 allocate_ssa_names (definitions, &ssa_name_map);
4699 rewrite_to_new_ssa_names (region, n_region, ssa_name_map);
4700 allocate_ssa_names (definitions, &ssa_name_map);
4701 rewrite_to_new_ssa_names (region_copy, n_region, ssa_name_map);
4702 htab_delete (ssa_name_map);
4704 if (free_region_copy)
4707 unmark_all_for_rewrite ();
4708 BITMAP_XFREE (definitions);
4713 /* Dump FUNCTION_DECL FN to file FILE using FLAGS (see TDF_* in tree.h) */
4716 dump_function_to_file (tree fn, FILE *file, int flags)
4718 tree arg, vars, var;
4719 bool ignore_topmost_bind = false, any_var = false;
4723 fprintf (file, "%s (", lang_hooks.decl_printable_name (fn, 2));
4725 arg = DECL_ARGUMENTS (fn);
4728 print_generic_expr (file, arg, dump_flags);
4729 if (TREE_CHAIN (arg))
4730 fprintf (file, ", ");
4731 arg = TREE_CHAIN (arg);
4733 fprintf (file, ")\n");
4735 if (flags & TDF_RAW)
4737 dump_node (fn, TDF_SLIM | flags, file);
4741 /* When GIMPLE is lowered, the variables are no longer available in
4742 BIND_EXPRs, so display them separately. */
4743 if (cfun && cfun->unexpanded_var_list)
4745 ignore_topmost_bind = true;
4747 fprintf (file, "{\n");
4748 for (vars = cfun->unexpanded_var_list; vars; vars = TREE_CHAIN (vars))
4750 var = TREE_VALUE (vars);
4752 print_generic_decl (file, var, flags);
4753 fprintf (file, "\n");
4759 if (basic_block_info)
4761 /* Make a CFG based dump. */
4762 check_bb_profile (ENTRY_BLOCK_PTR, file);
4763 if (!ignore_topmost_bind)
4764 fprintf (file, "{\n");
4766 if (any_var && n_basic_blocks)
4767 fprintf (file, "\n");
4770 dump_generic_bb (file, bb, 2, flags);
4772 fprintf (file, "}\n");
4773 check_bb_profile (EXIT_BLOCK_PTR, file);
4779 /* Make a tree based dump. */
4780 chain = DECL_SAVED_TREE (fn);
4782 if (TREE_CODE (chain) == BIND_EXPR)
4784 if (ignore_topmost_bind)
4786 chain = BIND_EXPR_BODY (chain);
4794 if (!ignore_topmost_bind)
4795 fprintf (file, "{\n");
4800 fprintf (file, "\n");
4802 print_generic_stmt_indented (file, chain, flags, indent);
4803 if (ignore_topmost_bind)
4804 fprintf (file, "}\n");
4807 fprintf (file, "\n\n");
4811 /* Pretty print of the loops intermediate representation. */
4812 static void print_loop (FILE *, struct loop *, int);
4813 static void print_pred_bbs (FILE *, basic_block bb);
4814 static void print_succ_bbs (FILE *, basic_block bb);
4817 /* Print the predecessors indexes of edge E on FILE. */
4820 print_pred_bbs (FILE *file, basic_block bb)
4825 FOR_EACH_EDGE (e, ei, bb->preds)
4826 fprintf (file, "bb_%d", e->src->index);
4830 /* Print the successors indexes of edge E on FILE. */
4833 print_succ_bbs (FILE *file, basic_block bb)
4838 FOR_EACH_EDGE (e, ei, bb->succs)
4839 fprintf (file, "bb_%d", e->src->index);
4843 /* Pretty print LOOP on FILE, indented INDENT spaces. */
4846 print_loop (FILE *file, struct loop *loop, int indent)
4854 s_indent = (char *) alloca ((size_t) indent + 1);
4855 memset ((void *) s_indent, ' ', (size_t) indent);
4856 s_indent[indent] = '\0';
4858 /* Print the loop's header. */
4859 fprintf (file, "%sloop_%d\n", s_indent, loop->num);
4861 /* Print the loop's body. */
4862 fprintf (file, "%s{\n", s_indent);
4864 if (bb->loop_father == loop)
4866 /* Print the basic_block's header. */
4867 fprintf (file, "%s bb_%d (preds = {", s_indent, bb->index);
4868 print_pred_bbs (file, bb);
4869 fprintf (file, "}, succs = {");
4870 print_succ_bbs (file, bb);
4871 fprintf (file, "})\n");
4873 /* Print the basic_block's body. */
4874 fprintf (file, "%s {\n", s_indent);
4875 tree_dump_bb (bb, file, indent + 4);
4876 fprintf (file, "%s }\n", s_indent);
4879 print_loop (file, loop->inner, indent + 2);
4880 fprintf (file, "%s}\n", s_indent);
4881 print_loop (file, loop->next, indent);
4885 /* Follow a CFG edge from the entry point of the program, and on entry
4886 of a loop, pretty print the loop structure on FILE. */
4889 print_loop_ir (FILE *file)
4893 bb = BASIC_BLOCK (0);
4894 if (bb && bb->loop_father)
4895 print_loop (file, bb->loop_father, 0);
4899 /* Debugging loops structure at tree level. */
4902 debug_loop_ir (void)
4904 print_loop_ir (stderr);
4908 /* Return true if BB ends with a call, possibly followed by some
4909 instructions that must stay with the call. Return false,
4913 tree_block_ends_with_call_p (basic_block bb)
4915 block_stmt_iterator bsi = bsi_last (bb);
4916 return get_call_expr_in (bsi_stmt (bsi)) != NULL;
4920 /* Return true if BB ends with a conditional branch. Return false,
4924 tree_block_ends_with_condjump_p (basic_block bb)
4926 tree stmt = tsi_stmt (bsi_last (bb).tsi);
4927 return (TREE_CODE (stmt) == COND_EXPR);
4931 /* Return true if we need to add fake edge to exit at statement T.
4932 Helper function for tree_flow_call_edges_add. */
4935 need_fake_edge_p (tree t)
4939 /* NORETURN and LONGJMP calls already have an edge to exit.
4940 CONST, PURE and ALWAYS_RETURN calls do not need one.
4941 We don't currently check for CONST and PURE here, although
4942 it would be a good idea, because those attributes are
4943 figured out from the RTL in mark_constant_function, and
4944 the counter incrementation code from -fprofile-arcs
4945 leads to different results from -fbranch-probabilities. */
4946 call = get_call_expr_in (t);
4948 && !(call_expr_flags (call) &
4949 (ECF_NORETURN | ECF_LONGJMP | ECF_ALWAYS_RETURN)))
4952 if (TREE_CODE (t) == ASM_EXPR
4953 && (ASM_VOLATILE_P (t) || ASM_INPUT_P (t)))
4960 /* Add fake edges to the function exit for any non constant and non
4961 noreturn calls, volatile inline assembly in the bitmap of blocks
4962 specified by BLOCKS or to the whole CFG if BLOCKS is zero. Return
4963 the number of blocks that were split.
4965 The goal is to expose cases in which entering a basic block does
4966 not imply that all subsequent instructions must be executed. */
4969 tree_flow_call_edges_add (sbitmap blocks)
4972 int blocks_split = 0;
4973 int last_bb = last_basic_block;
4974 bool check_last_block = false;
4976 if (n_basic_blocks == 0)
4980 check_last_block = true;
4982 check_last_block = TEST_BIT (blocks, EXIT_BLOCK_PTR->prev_bb->index);
4984 /* In the last basic block, before epilogue generation, there will be
4985 a fallthru edge to EXIT. Special care is required if the last insn
4986 of the last basic block is a call because make_edge folds duplicate
4987 edges, which would result in the fallthru edge also being marked
4988 fake, which would result in the fallthru edge being removed by
4989 remove_fake_edges, which would result in an invalid CFG.
4991 Moreover, we can't elide the outgoing fake edge, since the block
4992 profiler needs to take this into account in order to solve the minimal
4993 spanning tree in the case that the call doesn't return.
4995 Handle this by adding a dummy instruction in a new last basic block. */
4996 if (check_last_block)
4999 basic_block bb = EXIT_BLOCK_PTR->prev_bb;
5000 block_stmt_iterator bsi = bsi_last (bb);
5002 if (!bsi_end_p (bsi))
5005 if (need_fake_edge_p (t))
5009 FOR_EACH_EDGE (e, ei, bb->succs)
5010 if (e->dest == EXIT_BLOCK_PTR)
5012 bsi_insert_on_edge (e, build_empty_stmt ());
5013 bsi_commit_edge_inserts ((int *)NULL);
5019 /* Now add fake edges to the function exit for any non constant
5020 calls since there is no way that we can determine if they will
5022 for (i = 0; i < last_bb; i++)
5024 basic_block bb = BASIC_BLOCK (i);
5025 block_stmt_iterator bsi;
5026 tree stmt, last_stmt;
5031 if (blocks && !TEST_BIT (blocks, i))
5034 bsi = bsi_last (bb);
5035 if (!bsi_end_p (bsi))
5037 last_stmt = bsi_stmt (bsi);
5040 stmt = bsi_stmt (bsi);
5041 if (need_fake_edge_p (stmt))
5044 /* The handling above of the final block before the
5045 epilogue should be enough to verify that there is
5046 no edge to the exit block in CFG already.
5047 Calling make_edge in such case would cause us to
5048 mark that edge as fake and remove it later. */
5049 #ifdef ENABLE_CHECKING
5050 if (stmt == last_stmt)
5053 FOR_EACH_EDGE (e, ei, bb->succs)
5054 gcc_assert (e->dest != EXIT_BLOCK_PTR);
5058 /* Note that the following may create a new basic block
5059 and renumber the existing basic blocks. */
5060 if (stmt != last_stmt)
5062 e = split_block (bb, stmt);
5066 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
5070 while (!bsi_end_p (bsi));
5075 verify_flow_info ();
5077 return blocks_split;
5081 tree_purge_dead_eh_edges (basic_block bb)
5083 bool changed = false;
5086 tree stmt = last_stmt (bb);
5088 if (stmt && tree_can_throw_internal (stmt))
5091 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
5093 if (e->flags & EDGE_EH)
5095 ssa_remove_edge (e);
5102 /* Removal of dead EH edges might change dominators of not
5103 just immediate successors. E.g. when bb1 is changed so that
5104 it no longer can throw and bb1->bb3 and bb1->bb4 are dead
5105 eh edges purged by this function in:
5117 idom(bb5) must be recomputed. For now just free the dominance
5120 free_dominance_info (CDI_DOMINATORS);
5126 tree_purge_all_dead_eh_edges (bitmap blocks)
5128 bool changed = false;
5132 EXECUTE_IF_SET_IN_BITMAP (blocks, 0, i, bi)
5134 changed |= tree_purge_dead_eh_edges (BASIC_BLOCK (i));
5140 struct cfg_hooks tree_cfg_hooks = {
5142 tree_verify_flow_info,
5143 tree_dump_bb, /* dump_bb */
5144 create_bb, /* create_basic_block */
5145 tree_redirect_edge_and_branch,/* redirect_edge_and_branch */
5146 tree_redirect_edge_and_branch_force,/* redirect_edge_and_branch_force */
5147 remove_bb, /* delete_basic_block */
5148 tree_split_block, /* split_block */
5149 tree_move_block_after, /* move_block_after */
5150 tree_can_merge_blocks_p, /* can_merge_blocks_p */
5151 tree_merge_blocks, /* merge_blocks */
5152 tree_predict_edge, /* predict_edge */
5153 tree_predicted_by_p, /* predicted_by_p */
5154 tree_can_duplicate_bb_p, /* can_duplicate_block_p */
5155 tree_duplicate_bb, /* duplicate_block */
5156 tree_split_edge, /* split_edge */
5157 tree_make_forwarder_block, /* make_forward_block */
5158 NULL, /* tidy_fallthru_edge */
5159 tree_block_ends_with_call_p, /* block_ends_with_call_p */
5160 tree_block_ends_with_condjump_p, /* block_ends_with_condjump_p */
5161 tree_flow_call_edges_add /* flow_call_edges_add */
5165 /* Split all critical edges. */
5168 split_critical_edges (void)
5176 FOR_EACH_EDGE (e, ei, bb->succs)
5177 if (EDGE_CRITICAL_P (e) && !(e->flags & EDGE_ABNORMAL))
5184 struct tree_opt_pass pass_split_crit_edges =
5186 "crited", /* name */
5188 split_critical_edges, /* execute */
5191 0, /* static_pass_number */
5192 TV_TREE_SPLIT_EDGES, /* tv_id */
5193 PROP_cfg, /* properties required */
5194 PROP_no_crit_edges, /* properties_provided */
5195 0, /* properties_destroyed */
5196 0, /* todo_flags_start */
5197 TODO_dump_func, /* todo_flags_finish */
5202 /* Return EXP if it is a valid GIMPLE rvalue, else gimplify it into
5203 a temporary, make sure and register it to be renamed if necessary,
5204 and finally return the temporary. Put the statements to compute
5205 EXP before the current statement in BSI. */
5208 gimplify_val (block_stmt_iterator *bsi, tree type, tree exp)
5210 tree t, new_stmt, orig_stmt;
5212 if (is_gimple_val (exp))
5215 t = make_rename_temp (type, NULL);
5216 new_stmt = build (MODIFY_EXPR, type, t, exp);
5218 orig_stmt = bsi_stmt (*bsi);
5219 SET_EXPR_LOCUS (new_stmt, EXPR_LOCUS (orig_stmt));
5220 TREE_BLOCK (new_stmt) = TREE_BLOCK (orig_stmt);
5222 bsi_insert_before (bsi, new_stmt, BSI_SAME_STMT);
5227 /* Build a ternary operation and gimplify it. Emit code before BSI.
5228 Return the gimple_val holding the result. */
5231 gimplify_build3 (block_stmt_iterator *bsi, enum tree_code code,
5232 tree type, tree a, tree b, tree c)
5236 ret = fold (build3 (code, type, a, b, c));
5239 return gimplify_val (bsi, type, ret);
5242 /* Build a binary operation and gimplify it. Emit code before BSI.
5243 Return the gimple_val holding the result. */
5246 gimplify_build2 (block_stmt_iterator *bsi, enum tree_code code,
5247 tree type, tree a, tree b)
5251 ret = fold (build2 (code, type, a, b));
5254 return gimplify_val (bsi, type, ret);
5257 /* Build a unary operation and gimplify it. Emit code before BSI.
5258 Return the gimple_val holding the result. */
5261 gimplify_build1 (block_stmt_iterator *bsi, enum tree_code code, tree type,
5266 ret = fold (build1 (code, type, a));
5269 return gimplify_val (bsi, type, ret);
5274 /* Emit return warnings. */
5277 execute_warn_function_return (void)
5279 #ifdef USE_MAPPED_LOCATION
5280 source_location location;
5288 if (warn_missing_noreturn
5289 && !TREE_THIS_VOLATILE (cfun->decl)
5290 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) == 0
5291 && !lang_hooks.function.missing_noreturn_ok_p (cfun->decl))
5292 warning ("%Jfunction might be possible candidate for "
5293 "attribute %<noreturn%>",
5296 /* If we have a path to EXIT, then we do return. */
5297 if (TREE_THIS_VOLATILE (cfun->decl)
5298 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) > 0)
5300 #ifdef USE_MAPPED_LOCATION
5301 location = UNKNOWN_LOCATION;
5305 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
5307 last = last_stmt (e->src);
5308 if (TREE_CODE (last) == RETURN_EXPR
5309 #ifdef USE_MAPPED_LOCATION
5310 && (location = EXPR_LOCATION (last)) != UNKNOWN_LOCATION)
5312 && (locus = EXPR_LOCUS (last)) != NULL)
5316 #ifdef USE_MAPPED_LOCATION
5317 if (location == UNKNOWN_LOCATION)
5318 location = cfun->function_end_locus;
5319 warning ("%H%<noreturn%> function does return", &location);
5322 locus = &cfun->function_end_locus;
5323 warning ("%H%<noreturn%> function does return", locus);
5327 /* If we see "return;" in some basic block, then we do reach the end
5328 without returning a value. */
5329 else if (warn_return_type
5330 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) > 0
5331 && !VOID_TYPE_P (TREE_TYPE (TREE_TYPE (cfun->decl))))
5333 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
5335 tree last = last_stmt (e->src);
5336 if (TREE_CODE (last) == RETURN_EXPR
5337 && TREE_OPERAND (last, 0) == NULL)
5339 #ifdef USE_MAPPED_LOCATION
5340 location = EXPR_LOCATION (last);
5341 if (location == UNKNOWN_LOCATION)
5342 location = cfun->function_end_locus;
5343 warning ("%Hcontrol reaches end of non-void function", &location);
5345 locus = EXPR_LOCUS (last);
5347 locus = &cfun->function_end_locus;
5348 warning ("%Hcontrol reaches end of non-void function", locus);
5357 /* Given a basic block B which ends with a conditional and has
5358 precisely two successors, determine which of the edges is taken if
5359 the conditional is true and which is taken if the conditional is
5360 false. Set TRUE_EDGE and FALSE_EDGE appropriately. */
5363 extract_true_false_edges_from_block (basic_block b,
5367 edge e = EDGE_SUCC (b, 0);
5369 if (e->flags & EDGE_TRUE_VALUE)
5372 *false_edge = EDGE_SUCC (b, 1);
5377 *true_edge = EDGE_SUCC (b, 1);
5381 struct tree_opt_pass pass_warn_function_return =
5385 execute_warn_function_return, /* execute */
5388 0, /* static_pass_number */
5390 PROP_cfg, /* properties_required */
5391 0, /* properties_provided */
5392 0, /* properties_destroyed */
5393 0, /* todo_flags_start */
5394 0, /* todo_flags_finish */
5398 #include "gt-tree-cfg.h"