1 /* Control flow functions for trees.
2 Copyright (C) 2001, 2002, 2003, 2004, 2005 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, 51 Franklin Street, Fifth Floor,
20 Boston, MA 02110-1301, USA. */
24 #include "coretypes.h"
29 #include "hard-reg-set.h"
30 #include "basic-block.h"
36 #include "langhooks.h"
37 #include "diagnostic.h"
38 #include "tree-flow.h"
40 #include "tree-dump.h"
41 #include "tree-pass.h"
45 #include "cfglayout.h"
47 #include "tree-ssa-propagate.h"
49 /* This file contains functions for building the Control Flow Graph (CFG)
50 for a function tree. */
52 /* Local declarations. */
54 /* Initial capacity for the basic block array. */
55 static const int initial_cfg_capacity = 20;
57 /* This hash table allows us to efficiently lookup all CASE_LABEL_EXPRs
58 which use a particular edge. The CASE_LABEL_EXPRs are chained together
59 via their TREE_CHAIN field, which we clear after we're done with the
60 hash table to prevent problems with duplication of SWITCH_EXPRs.
62 Access to this list of CASE_LABEL_EXPRs allows us to efficiently
63 update the case vector in response to edge redirections.
65 Right now this table is set up and torn down at key points in the
66 compilation process. It would be nice if we could make the table
67 more persistent. The key is getting notification of changes to
68 the CFG (particularly edge removal, creation and redirection). */
70 struct edge_to_cases_elt
72 /* The edge itself. Necessary for hashing and equality tests. */
75 /* The case labels associated with this edge. We link these up via
76 their TREE_CHAIN field, then we wipe out the TREE_CHAIN fields
77 when we destroy the hash table. This prevents problems when copying
82 static htab_t edge_to_cases;
87 long num_merged_labels;
90 static struct cfg_stats_d cfg_stats;
92 /* Nonzero if we found a computed goto while building basic blocks. */
93 static bool found_computed_goto;
95 /* Basic blocks and flowgraphs. */
96 static basic_block create_bb (void *, void *, basic_block);
97 static void make_blocks (tree);
98 static void factor_computed_gotos (void);
101 static void make_edges (void);
102 static void make_ctrl_stmt_edges (basic_block);
103 static void make_exit_edges (basic_block);
104 static void make_cond_expr_edges (basic_block);
105 static void make_switch_expr_edges (basic_block);
106 static void make_goto_expr_edges (basic_block);
107 static edge tree_redirect_edge_and_branch (edge, basic_block);
108 static edge tree_try_redirect_by_replacing_jump (edge, basic_block);
109 static void split_critical_edges (void);
111 /* Various helpers. */
112 static inline bool stmt_starts_bb_p (tree, tree);
113 static int tree_verify_flow_info (void);
114 static void tree_make_forwarder_block (edge);
115 static void tree_cfg2vcg (FILE *);
117 /* Flowgraph optimization and cleanup. */
118 static void tree_merge_blocks (basic_block, basic_block);
119 static bool tree_can_merge_blocks_p (basic_block, basic_block);
120 static void remove_bb (basic_block);
121 static edge find_taken_edge_computed_goto (basic_block, tree);
122 static edge find_taken_edge_cond_expr (basic_block, tree);
123 static edge find_taken_edge_switch_expr (basic_block, tree);
124 static tree find_case_label_for_value (tree, tree);
127 init_empty_tree_cfg (void)
129 /* Initialize the basic block array. */
131 profile_status = PROFILE_ABSENT;
132 n_basic_blocks = NUM_FIXED_BLOCKS;
133 last_basic_block = NUM_FIXED_BLOCKS;
134 basic_block_info = VEC_alloc (basic_block, gc, initial_cfg_capacity);
135 VEC_safe_grow (basic_block, gc, basic_block_info, initial_cfg_capacity);
136 memset (VEC_address (basic_block, basic_block_info), 0,
137 sizeof (basic_block) * initial_cfg_capacity);
139 /* Build a mapping of labels to their associated blocks. */
140 label_to_block_map = VEC_alloc (basic_block, gc, initial_cfg_capacity);
141 VEC_safe_grow (basic_block, gc, label_to_block_map, initial_cfg_capacity);
142 memset (VEC_address (basic_block, label_to_block_map),
143 0, sizeof (basic_block) * initial_cfg_capacity);
145 SET_BASIC_BLOCK (ENTRY_BLOCK, ENTRY_BLOCK_PTR);
146 SET_BASIC_BLOCK (EXIT_BLOCK, EXIT_BLOCK_PTR);
147 ENTRY_BLOCK_PTR->next_bb = EXIT_BLOCK_PTR;
148 EXIT_BLOCK_PTR->prev_bb = ENTRY_BLOCK_PTR;
151 /*---------------------------------------------------------------------------
153 ---------------------------------------------------------------------------*/
155 /* Entry point to the CFG builder for trees. TP points to the list of
156 statements to be added to the flowgraph. */
159 build_tree_cfg (tree *tp)
161 /* Register specific tree functions. */
162 tree_register_cfg_hooks ();
164 memset ((void *) &cfg_stats, 0, sizeof (cfg_stats));
166 init_empty_tree_cfg ();
168 found_computed_goto = 0;
171 /* Computed gotos are hell to deal with, especially if there are
172 lots of them with a large number of destinations. So we factor
173 them to a common computed goto location before we build the
174 edge list. After we convert back to normal form, we will un-factor
175 the computed gotos since factoring introduces an unwanted jump. */
176 if (found_computed_goto)
177 factor_computed_gotos ();
179 /* Make sure there is always at least one block, even if it's empty. */
180 if (n_basic_blocks == NUM_FIXED_BLOCKS)
181 create_empty_bb (ENTRY_BLOCK_PTR);
183 /* Adjust the size of the array. */
184 if (VEC_length (basic_block, basic_block_info) < (size_t) n_basic_blocks)
186 size_t old_size = VEC_length (basic_block, basic_block_info);
188 VEC_safe_grow (basic_block, gc, basic_block_info, n_basic_blocks);
189 p = VEC_address (basic_block, basic_block_info);
190 memset (&p[old_size], 0,
191 sizeof (basic_block) * (n_basic_blocks - old_size));
194 /* To speed up statement iterator walks, we first purge dead labels. */
195 cleanup_dead_labels ();
197 /* Group case nodes to reduce the number of edges.
198 We do this after cleaning up dead labels because otherwise we miss
199 a lot of obvious case merging opportunities. */
200 group_case_labels ();
202 /* Create the edges of the flowgraph. */
205 /* Debugging dumps. */
207 /* Write the flowgraph to a VCG file. */
209 int local_dump_flags;
210 FILE *dump_file = dump_begin (TDI_vcg, &local_dump_flags);
213 tree_cfg2vcg (dump_file);
214 dump_end (TDI_vcg, dump_file);
218 #ifdef ENABLE_CHECKING
222 /* Dump a textual representation of the flowgraph. */
224 dump_tree_cfg (dump_file, dump_flags);
228 execute_build_cfg (void)
230 build_tree_cfg (&DECL_SAVED_TREE (current_function_decl));
233 struct tree_opt_pass pass_build_cfg =
237 execute_build_cfg, /* execute */
240 0, /* static_pass_number */
241 TV_TREE_CFG, /* tv_id */
242 PROP_gimple_leh, /* properties_required */
243 PROP_cfg, /* properties_provided */
244 0, /* properties_destroyed */
245 0, /* todo_flags_start */
246 TODO_verify_stmts, /* todo_flags_finish */
250 /* Search the CFG for any computed gotos. If found, factor them to a
251 common computed goto site. Also record the location of that site so
252 that we can un-factor the gotos after we have converted back to
256 factor_computed_gotos (void)
259 tree factored_label_decl = NULL;
261 tree factored_computed_goto_label = NULL;
262 tree factored_computed_goto = NULL;
264 /* We know there are one or more computed gotos in this function.
265 Examine the last statement in each basic block to see if the block
266 ends with a computed goto. */
270 block_stmt_iterator bsi = bsi_last (bb);
275 last = bsi_stmt (bsi);
277 /* Ignore the computed goto we create when we factor the original
279 if (last == factored_computed_goto)
282 /* If the last statement is a computed goto, factor it. */
283 if (computed_goto_p (last))
287 /* The first time we find a computed goto we need to create
288 the factored goto block and the variable each original
289 computed goto will use for their goto destination. */
290 if (! factored_computed_goto)
292 basic_block new_bb = create_empty_bb (bb);
293 block_stmt_iterator new_bsi = bsi_start (new_bb);
295 /* Create the destination of the factored goto. Each original
296 computed goto will put its desired destination into this
297 variable and jump to the label we create immediately
299 var = create_tmp_var (ptr_type_node, "gotovar");
301 /* Build a label for the new block which will contain the
302 factored computed goto. */
303 factored_label_decl = create_artificial_label ();
304 factored_computed_goto_label
305 = build1 (LABEL_EXPR, void_type_node, factored_label_decl);
306 bsi_insert_after (&new_bsi, factored_computed_goto_label,
309 /* Build our new computed goto. */
310 factored_computed_goto = build1 (GOTO_EXPR, void_type_node, var);
311 bsi_insert_after (&new_bsi, factored_computed_goto,
315 /* Copy the original computed goto's destination into VAR. */
316 assignment = build2 (MODIFY_EXPR, ptr_type_node,
317 var, GOTO_DESTINATION (last));
318 bsi_insert_before (&bsi, assignment, BSI_SAME_STMT);
320 /* And re-vector the computed goto to the new destination. */
321 GOTO_DESTINATION (last) = factored_label_decl;
327 /* Build a flowgraph for the statement_list STMT_LIST. */
330 make_blocks (tree stmt_list)
332 tree_stmt_iterator i = tsi_start (stmt_list);
334 bool start_new_block = true;
335 bool first_stmt_of_list = true;
336 basic_block bb = ENTRY_BLOCK_PTR;
338 while (!tsi_end_p (i))
345 /* If the statement starts a new basic block or if we have determined
346 in a previous pass that we need to create a new block for STMT, do
348 if (start_new_block || stmt_starts_bb_p (stmt, prev_stmt))
350 if (!first_stmt_of_list)
351 stmt_list = tsi_split_statement_list_before (&i);
352 bb = create_basic_block (stmt_list, NULL, bb);
353 start_new_block = false;
356 /* Now add STMT to BB and create the subgraphs for special statement
358 set_bb_for_stmt (stmt, bb);
360 if (computed_goto_p (stmt))
361 found_computed_goto = true;
363 /* If STMT is a basic block terminator, set START_NEW_BLOCK for the
365 if (stmt_ends_bb_p (stmt))
366 start_new_block = true;
369 first_stmt_of_list = false;
374 /* Create and return a new empty basic block after bb AFTER. */
377 create_bb (void *h, void *e, basic_block after)
383 /* Create and initialize a new basic block. Since alloc_block uses
384 ggc_alloc_cleared to allocate a basic block, we do not have to
385 clear the newly allocated basic block here. */
388 bb->index = last_basic_block;
390 bb->stmt_list = h ? (tree) h : alloc_stmt_list ();
392 /* Add the new block to the linked list of blocks. */
393 link_block (bb, after);
395 /* Grow the basic block array if needed. */
396 if ((size_t) last_basic_block == VEC_length (basic_block, basic_block_info))
398 size_t old_size = VEC_length (basic_block, basic_block_info);
399 size_t new_size = last_basic_block + (last_basic_block + 3) / 4;
401 VEC_safe_grow (basic_block, gc, basic_block_info, new_size);
402 p = VEC_address (basic_block, basic_block_info);
403 memset (&p[old_size], 0, sizeof (basic_block) * (new_size - old_size));
406 /* Add the newly created block to the array. */
407 SET_BASIC_BLOCK (last_basic_block, bb);
416 /*---------------------------------------------------------------------------
418 ---------------------------------------------------------------------------*/
420 /* Fold COND_EXPR_COND of each COND_EXPR. */
423 fold_cond_expr_cond (void)
429 tree stmt = last_stmt (bb);
432 && TREE_CODE (stmt) == COND_EXPR)
434 tree cond = fold (COND_EXPR_COND (stmt));
435 if (integer_zerop (cond))
436 COND_EXPR_COND (stmt) = boolean_false_node;
437 else if (integer_onep (cond))
438 COND_EXPR_COND (stmt) = boolean_true_node;
443 /* Join all the blocks in the flowgraph. */
450 /* Create an edge from entry to the first block with executable
452 make_edge (ENTRY_BLOCK_PTR, BASIC_BLOCK (NUM_FIXED_BLOCKS), EDGE_FALLTHRU);
454 /* Traverse the basic block array placing edges. */
457 tree first = first_stmt (bb);
458 tree last = last_stmt (bb);
462 /* Edges for statements that always alter flow control. */
463 if (is_ctrl_stmt (last))
464 make_ctrl_stmt_edges (bb);
466 /* Edges for statements that sometimes alter flow control. */
467 if (is_ctrl_altering_stmt (last))
468 make_exit_edges (bb);
471 /* Finally, if no edges were created above, this is a regular
472 basic block that only needs a fallthru edge. */
473 if (EDGE_COUNT (bb->succs) == 0)
474 make_edge (bb, bb->next_bb, EDGE_FALLTHRU);
477 /* We do not care about fake edges, so remove any that the CFG
478 builder inserted for completeness. */
479 remove_fake_exit_edges ();
481 /* Fold COND_EXPR_COND of each COND_EXPR. */
482 fold_cond_expr_cond ();
484 /* Clean up the graph and warn for unreachable code. */
489 /* Create edges for control statement at basic block BB. */
492 make_ctrl_stmt_edges (basic_block bb)
494 tree last = last_stmt (bb);
497 switch (TREE_CODE (last))
500 make_goto_expr_edges (bb);
504 make_edge (bb, EXIT_BLOCK_PTR, 0);
508 make_cond_expr_edges (bb);
512 make_switch_expr_edges (bb);
516 make_eh_edges (last);
517 /* Yet another NORETURN hack. */
518 if (EDGE_COUNT (bb->succs) == 0)
519 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
528 /* Create exit edges for statements in block BB that alter the flow of
529 control. Statements that alter the control flow are 'goto', 'return'
530 and calls to non-returning functions. */
533 make_exit_edges (basic_block bb)
535 tree last = last_stmt (bb), op;
538 switch (TREE_CODE (last))
543 /* If this function receives a nonlocal goto, then we need to
544 make edges from this call site to all the nonlocal goto
546 if (TREE_SIDE_EFFECTS (last)
547 && current_function_has_nonlocal_label)
548 make_goto_expr_edges (bb);
550 /* If this statement has reachable exception handlers, then
551 create abnormal edges to them. */
552 make_eh_edges (last);
554 /* Some calls are known not to return. For such calls we create
557 We really need to revamp how we build edges so that it's not
558 such a bloody pain to avoid creating edges for this case since
559 all we do is remove these edges when we're done building the
561 if (call_expr_flags (last) & ECF_NORETURN)
563 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
567 /* Don't forget the fall-thru edge. */
568 make_edge (bb, bb->next_bb, EDGE_FALLTHRU);
572 /* A MODIFY_EXPR may have a CALL_EXPR on its RHS and the CALL_EXPR
573 may have an abnormal edge. Search the RHS for this case and
574 create any required edges. */
575 op = get_call_expr_in (last);
576 if (op && TREE_SIDE_EFFECTS (op)
577 && current_function_has_nonlocal_label)
578 make_goto_expr_edges (bb);
580 make_eh_edges (last);
581 make_edge (bb, bb->next_bb, EDGE_FALLTHRU);
590 /* Create the edges for a COND_EXPR starting at block BB.
591 At this point, both clauses must contain only simple gotos. */
594 make_cond_expr_edges (basic_block bb)
596 tree entry = last_stmt (bb);
597 basic_block then_bb, else_bb;
598 tree then_label, else_label;
602 gcc_assert (TREE_CODE (entry) == COND_EXPR);
604 /* Entry basic blocks for each component. */
605 then_label = GOTO_DESTINATION (COND_EXPR_THEN (entry));
606 else_label = GOTO_DESTINATION (COND_EXPR_ELSE (entry));
607 then_bb = label_to_block (then_label);
608 else_bb = label_to_block (else_label);
610 e = make_edge (bb, then_bb, EDGE_TRUE_VALUE);
611 #ifdef USE_MAPPED_LOCATION
612 e->goto_locus = EXPR_LOCATION (COND_EXPR_THEN (entry));
614 e->goto_locus = EXPR_LOCUS (COND_EXPR_THEN (entry));
616 e = make_edge (bb, else_bb, EDGE_FALSE_VALUE);
619 #ifdef USE_MAPPED_LOCATION
620 e->goto_locus = EXPR_LOCATION (COND_EXPR_ELSE (entry));
622 e->goto_locus = EXPR_LOCUS (COND_EXPR_ELSE (entry));
627 /* Hashing routine for EDGE_TO_CASES. */
630 edge_to_cases_hash (const void *p)
632 edge e = ((struct edge_to_cases_elt *)p)->e;
634 /* Hash on the edge itself (which is a pointer). */
635 return htab_hash_pointer (e);
638 /* Equality routine for EDGE_TO_CASES, edges are unique, so testing
639 for equality is just a pointer comparison. */
642 edge_to_cases_eq (const void *p1, const void *p2)
644 edge e1 = ((struct edge_to_cases_elt *)p1)->e;
645 edge e2 = ((struct edge_to_cases_elt *)p2)->e;
650 /* Called for each element in the hash table (P) as we delete the
651 edge to cases hash table.
653 Clear all the TREE_CHAINs to prevent problems with copying of
654 SWITCH_EXPRs and structure sharing rules, then free the hash table
658 edge_to_cases_cleanup (void *p)
660 struct edge_to_cases_elt *elt = (struct edge_to_cases_elt *) p;
663 for (t = elt->case_labels; t; t = next)
665 next = TREE_CHAIN (t);
666 TREE_CHAIN (t) = NULL;
671 /* Start recording information mapping edges to case labels. */
674 start_recording_case_labels (void)
676 gcc_assert (edge_to_cases == NULL);
678 edge_to_cases = htab_create (37,
681 edge_to_cases_cleanup);
684 /* Return nonzero if we are recording information for case labels. */
687 recording_case_labels_p (void)
689 return (edge_to_cases != NULL);
692 /* Stop recording information mapping edges to case labels and
693 remove any information we have recorded. */
695 end_recording_case_labels (void)
697 htab_delete (edge_to_cases);
698 edge_to_cases = NULL;
701 /* Record that CASE_LABEL (a CASE_LABEL_EXPR) references edge E. */
704 record_switch_edge (edge e, tree case_label)
706 struct edge_to_cases_elt *elt;
709 /* Build a hash table element so we can see if E is already
711 elt = XNEW (struct edge_to_cases_elt);
713 elt->case_labels = case_label;
715 slot = htab_find_slot (edge_to_cases, elt, INSERT);
719 /* E was not in the hash table. Install E into the hash table. */
724 /* E was already in the hash table. Free ELT as we do not need it
728 /* Get the entry stored in the hash table. */
729 elt = (struct edge_to_cases_elt *) *slot;
731 /* Add it to the chain of CASE_LABEL_EXPRs referencing E. */
732 TREE_CHAIN (case_label) = elt->case_labels;
733 elt->case_labels = case_label;
737 /* If we are inside a {start,end}_recording_cases block, then return
738 a chain of CASE_LABEL_EXPRs from T which reference E.
740 Otherwise return NULL. */
743 get_cases_for_edge (edge e, tree t)
745 struct edge_to_cases_elt elt, *elt_p;
750 /* If we are not recording cases, then we do not have CASE_LABEL_EXPR
751 chains available. Return NULL so the caller can detect this case. */
752 if (!recording_case_labels_p ())
757 elt.case_labels = NULL;
758 slot = htab_find_slot (edge_to_cases, &elt, NO_INSERT);
762 elt_p = (struct edge_to_cases_elt *)*slot;
763 return elt_p->case_labels;
766 /* If we did not find E in the hash table, then this must be the first
767 time we have been queried for information about E & T. Add all the
768 elements from T to the hash table then perform the query again. */
770 vec = SWITCH_LABELS (t);
771 n = TREE_VEC_LENGTH (vec);
772 for (i = 0; i < n; i++)
774 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
775 basic_block label_bb = label_to_block (lab);
776 record_switch_edge (find_edge (e->src, label_bb), TREE_VEC_ELT (vec, i));
781 /* Create the edges for a SWITCH_EXPR starting at block BB.
782 At this point, the switch body has been lowered and the
783 SWITCH_LABELS filled in, so this is in effect a multi-way branch. */
786 make_switch_expr_edges (basic_block bb)
788 tree entry = last_stmt (bb);
792 vec = SWITCH_LABELS (entry);
793 n = TREE_VEC_LENGTH (vec);
795 for (i = 0; i < n; ++i)
797 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
798 basic_block label_bb = label_to_block (lab);
799 make_edge (bb, label_bb, 0);
804 /* Return the basic block holding label DEST. */
807 label_to_block_fn (struct function *ifun, tree dest)
809 int uid = LABEL_DECL_UID (dest);
811 /* We would die hard when faced by an undefined label. Emit a label to
812 the very first basic block. This will hopefully make even the dataflow
813 and undefined variable warnings quite right. */
814 if ((errorcount || sorrycount) && uid < 0)
816 block_stmt_iterator bsi =
817 bsi_start (BASIC_BLOCK (NUM_FIXED_BLOCKS));
820 stmt = build1 (LABEL_EXPR, void_type_node, dest);
821 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
822 uid = LABEL_DECL_UID (dest);
824 if (VEC_length (basic_block, ifun->cfg->x_label_to_block_map)
825 <= (unsigned int) uid)
827 return VEC_index (basic_block, ifun->cfg->x_label_to_block_map, uid);
830 /* Create edges for a goto statement at block BB. */
833 make_goto_expr_edges (basic_block bb)
836 basic_block target_bb;
838 block_stmt_iterator last = bsi_last (bb);
840 goto_t = bsi_stmt (last);
842 /* If the last statement is not a GOTO (i.e., it is a RETURN_EXPR,
843 CALL_EXPR or MODIFY_EXPR), then the edge is an abnormal edge resulting
844 from a nonlocal goto. */
845 if (TREE_CODE (goto_t) != GOTO_EXPR)
849 tree dest = GOTO_DESTINATION (goto_t);
852 /* A GOTO to a local label creates normal edges. */
853 if (simple_goto_p (goto_t))
855 edge e = make_edge (bb, label_to_block (dest), EDGE_FALLTHRU);
856 #ifdef USE_MAPPED_LOCATION
857 e->goto_locus = EXPR_LOCATION (goto_t);
859 e->goto_locus = EXPR_LOCUS (goto_t);
861 bsi_remove (&last, true);
865 /* Nothing more to do for nonlocal gotos. */
866 if (TREE_CODE (dest) == LABEL_DECL)
869 /* Computed gotos remain. */
872 /* Look for the block starting with the destination label. In the
873 case of a computed goto, make an edge to any label block we find
875 FOR_EACH_BB (target_bb)
877 block_stmt_iterator bsi;
879 for (bsi = bsi_start (target_bb); !bsi_end_p (bsi); bsi_next (&bsi))
881 tree target = bsi_stmt (bsi);
883 if (TREE_CODE (target) != LABEL_EXPR)
887 /* Computed GOTOs. Make an edge to every label block that has
888 been marked as a potential target for a computed goto. */
889 (FORCED_LABEL (LABEL_EXPR_LABEL (target)) && for_call == 0)
890 /* Nonlocal GOTO target. Make an edge to every label block
891 that has been marked as a potential target for a nonlocal
893 || (DECL_NONLOCAL (LABEL_EXPR_LABEL (target)) && for_call == 1))
895 make_edge (bb, target_bb, EDGE_ABNORMAL);
901 /* Degenerate case of computed goto with no labels. */
902 if (!for_call && EDGE_COUNT (bb->succs) == 0)
903 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
907 /*---------------------------------------------------------------------------
909 ---------------------------------------------------------------------------*/
911 /* Cleanup useless labels in basic blocks. This is something we wish
912 to do early because it allows us to group case labels before creating
913 the edges for the CFG, and it speeds up block statement iterators in
915 We only run this pass once, running it more than once is probably not
918 /* A map from basic block index to the leading label of that block. */
919 static tree *label_for_bb;
921 /* Callback for for_each_eh_region. Helper for cleanup_dead_labels. */
923 update_eh_label (struct eh_region *region)
925 tree old_label = get_eh_region_tree_label (region);
929 basic_block bb = label_to_block (old_label);
931 /* ??? After optimizing, there may be EH regions with labels
932 that have already been removed from the function body, so
933 there is no basic block for them. */
937 new_label = label_for_bb[bb->index];
938 set_eh_region_tree_label (region, new_label);
942 /* Given LABEL return the first label in the same basic block. */
944 main_block_label (tree label)
946 basic_block bb = label_to_block (label);
948 /* label_to_block possibly inserted undefined label into the chain. */
949 if (!label_for_bb[bb->index])
950 label_for_bb[bb->index] = label;
951 return label_for_bb[bb->index];
954 /* Cleanup redundant labels. This is a three-step process:
955 1) Find the leading label for each block.
956 2) Redirect all references to labels to the leading labels.
957 3) Cleanup all useless labels. */
960 cleanup_dead_labels (void)
963 label_for_bb = XCNEWVEC (tree, last_basic_block);
965 /* Find a suitable label for each block. We use the first user-defined
966 label if there is one, or otherwise just the first label we see. */
969 block_stmt_iterator i;
971 for (i = bsi_start (bb); !bsi_end_p (i); bsi_next (&i))
973 tree label, stmt = bsi_stmt (i);
975 if (TREE_CODE (stmt) != LABEL_EXPR)
978 label = LABEL_EXPR_LABEL (stmt);
980 /* If we have not yet seen a label for the current block,
981 remember this one and see if there are more labels. */
982 if (! label_for_bb[bb->index])
984 label_for_bb[bb->index] = label;
988 /* If we did see a label for the current block already, but it
989 is an artificially created label, replace it if the current
990 label is a user defined label. */
991 if (! DECL_ARTIFICIAL (label)
992 && DECL_ARTIFICIAL (label_for_bb[bb->index]))
994 label_for_bb[bb->index] = label;
1000 /* Now redirect all jumps/branches to the selected label.
1001 First do so for each block ending in a control statement. */
1004 tree stmt = last_stmt (bb);
1008 switch (TREE_CODE (stmt))
1012 tree true_branch, false_branch;
1014 true_branch = COND_EXPR_THEN (stmt);
1015 false_branch = COND_EXPR_ELSE (stmt);
1017 GOTO_DESTINATION (true_branch)
1018 = main_block_label (GOTO_DESTINATION (true_branch));
1019 GOTO_DESTINATION (false_branch)
1020 = main_block_label (GOTO_DESTINATION (false_branch));
1028 tree vec = SWITCH_LABELS (stmt);
1029 size_t n = TREE_VEC_LENGTH (vec);
1031 /* Replace all destination labels. */
1032 for (i = 0; i < n; ++i)
1034 tree elt = TREE_VEC_ELT (vec, i);
1035 tree label = main_block_label (CASE_LABEL (elt));
1036 CASE_LABEL (elt) = label;
1041 /* We have to handle GOTO_EXPRs until they're removed, and we don't
1042 remove them until after we've created the CFG edges. */
1044 if (! computed_goto_p (stmt))
1046 GOTO_DESTINATION (stmt)
1047 = main_block_label (GOTO_DESTINATION (stmt));
1056 for_each_eh_region (update_eh_label);
1058 /* Finally, purge dead labels. All user-defined labels and labels that
1059 can be the target of non-local gotos are preserved. */
1062 block_stmt_iterator i;
1063 tree label_for_this_bb = label_for_bb[bb->index];
1065 if (! label_for_this_bb)
1068 for (i = bsi_start (bb); !bsi_end_p (i); )
1070 tree label, stmt = bsi_stmt (i);
1072 if (TREE_CODE (stmt) != LABEL_EXPR)
1075 label = LABEL_EXPR_LABEL (stmt);
1077 if (label == label_for_this_bb
1078 || ! DECL_ARTIFICIAL (label)
1079 || DECL_NONLOCAL (label))
1082 bsi_remove (&i, true);
1086 free (label_for_bb);
1089 /* Look for blocks ending in a multiway branch (a SWITCH_EXPR in GIMPLE),
1090 and scan the sorted vector of cases. Combine the ones jumping to the
1092 Eg. three separate entries 1: 2: 3: become one entry 1..3: */
1095 group_case_labels (void)
1101 tree stmt = last_stmt (bb);
1102 if (stmt && TREE_CODE (stmt) == SWITCH_EXPR)
1104 tree labels = SWITCH_LABELS (stmt);
1105 int old_size = TREE_VEC_LENGTH (labels);
1106 int i, j, new_size = old_size;
1107 tree default_case = TREE_VEC_ELT (labels, old_size - 1);
1110 /* The default label is always the last case in a switch
1111 statement after gimplification. */
1112 default_label = CASE_LABEL (default_case);
1114 /* Look for possible opportunities to merge cases.
1115 Ignore the last element of the label vector because it
1116 must be the default case. */
1118 while (i < old_size - 1)
1120 tree base_case, base_label, base_high;
1121 base_case = TREE_VEC_ELT (labels, i);
1123 gcc_assert (base_case);
1124 base_label = CASE_LABEL (base_case);
1126 /* Discard cases that have the same destination as the
1128 if (base_label == default_label)
1130 TREE_VEC_ELT (labels, i) = NULL_TREE;
1136 base_high = CASE_HIGH (base_case) ?
1137 CASE_HIGH (base_case) : CASE_LOW (base_case);
1139 /* Try to merge case labels. Break out when we reach the end
1140 of the label vector or when we cannot merge the next case
1141 label with the current one. */
1142 while (i < old_size - 1)
1144 tree merge_case = TREE_VEC_ELT (labels, i);
1145 tree merge_label = CASE_LABEL (merge_case);
1146 tree t = int_const_binop (PLUS_EXPR, base_high,
1147 integer_one_node, 1);
1149 /* Merge the cases if they jump to the same place,
1150 and their ranges are consecutive. */
1151 if (merge_label == base_label
1152 && tree_int_cst_equal (CASE_LOW (merge_case), t))
1154 base_high = CASE_HIGH (merge_case) ?
1155 CASE_HIGH (merge_case) : CASE_LOW (merge_case);
1156 CASE_HIGH (base_case) = base_high;
1157 TREE_VEC_ELT (labels, i) = NULL_TREE;
1166 /* Compress the case labels in the label vector, and adjust the
1167 length of the vector. */
1168 for (i = 0, j = 0; i < new_size; i++)
1170 while (! TREE_VEC_ELT (labels, j))
1172 TREE_VEC_ELT (labels, i) = TREE_VEC_ELT (labels, j++);
1174 TREE_VEC_LENGTH (labels) = new_size;
1179 /* Checks whether we can merge block B into block A. */
1182 tree_can_merge_blocks_p (basic_block a, basic_block b)
1185 block_stmt_iterator bsi;
1188 if (!single_succ_p (a))
1191 if (single_succ_edge (a)->flags & EDGE_ABNORMAL)
1194 if (single_succ (a) != b)
1197 if (!single_pred_p (b))
1200 if (b == EXIT_BLOCK_PTR)
1203 /* If A ends by a statement causing exceptions or something similar, we
1204 cannot merge the blocks. */
1205 stmt = last_stmt (a);
1206 if (stmt && stmt_ends_bb_p (stmt))
1209 /* Do not allow a block with only a non-local label to be merged. */
1210 if (stmt && TREE_CODE (stmt) == LABEL_EXPR
1211 && DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)))
1214 /* It must be possible to eliminate all phi nodes in B. If ssa form
1215 is not up-to-date, we cannot eliminate any phis. */
1216 phi = phi_nodes (b);
1219 if (need_ssa_update_p ())
1222 for (; phi; phi = PHI_CHAIN (phi))
1223 if (!is_gimple_reg (PHI_RESULT (phi))
1224 && !may_propagate_copy (PHI_RESULT (phi), PHI_ARG_DEF (phi, 0)))
1228 /* Do not remove user labels. */
1229 for (bsi = bsi_start (b); !bsi_end_p (bsi); bsi_next (&bsi))
1231 stmt = bsi_stmt (bsi);
1232 if (TREE_CODE (stmt) != LABEL_EXPR)
1234 if (!DECL_ARTIFICIAL (LABEL_EXPR_LABEL (stmt)))
1238 /* Protect the loop latches. */
1240 && b->loop_father->latch == b)
1246 /* Replaces all uses of NAME by VAL. */
1249 replace_uses_by (tree name, tree val)
1251 imm_use_iterator imm_iter;
1256 VEC(tree,heap) *stmts = VEC_alloc (tree, heap, 20);
1258 FOR_EACH_IMM_USE_SAFE (use, imm_iter, name)
1260 stmt = USE_STMT (use);
1261 replace_exp (use, val);
1263 if (TREE_CODE (stmt) == PHI_NODE)
1265 e = PHI_ARG_EDGE (stmt, PHI_ARG_INDEX_FROM_USE (use));
1266 if (e->flags & EDGE_ABNORMAL)
1268 /* This can only occur for virtual operands, since
1269 for the real ones SSA_NAME_OCCURS_IN_ABNORMAL_PHI (name))
1270 would prevent replacement. */
1271 gcc_assert (!is_gimple_reg (name));
1272 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (val) = 1;
1276 VEC_safe_push (tree, heap, stmts, stmt);
1279 /* We do not update the statements in the loop above. Consider
1282 If we performed the update in the first loop, the statement
1283 would be rescanned after first occurrence of w is replaced,
1284 the new uses would be placed to the beginning of the list,
1285 and we would never process them. */
1286 for (i = 0; VEC_iterate (tree, stmts, i, stmt); i++)
1290 fold_stmt_inplace (stmt);
1292 rhs = get_rhs (stmt);
1293 if (TREE_CODE (rhs) == ADDR_EXPR)
1294 recompute_tree_invariant_for_addr_expr (rhs);
1296 /* If the statement could throw and now cannot, we need to prune cfg. */
1297 if (maybe_clean_or_replace_eh_stmt (stmt, stmt))
1298 tree_purge_dead_eh_edges (bb_for_stmt (stmt));
1300 mark_new_vars_to_rename (stmt);
1303 VEC_free (tree, heap, stmts);
1305 /* Also update the trees stored in loop structures. */
1310 for (i = 0; i < current_loops->num; i++)
1312 loop = current_loops->parray[i];
1314 substitute_in_loop_info (loop, name, val);
1319 /* Merge block B into block A. */
1322 tree_merge_blocks (basic_block a, basic_block b)
1324 block_stmt_iterator bsi;
1325 tree_stmt_iterator last;
1329 fprintf (dump_file, "Merging blocks %d and %d\n", a->index, b->index);
1331 /* Remove all single-valued PHI nodes from block B of the form
1332 V_i = PHI <V_j> by propagating V_j to all the uses of V_i. */
1334 for (phi = phi_nodes (b); phi; phi = phi_nodes (b))
1336 tree def = PHI_RESULT (phi), use = PHI_ARG_DEF (phi, 0);
1338 bool may_replace_uses = may_propagate_copy (def, use);
1340 /* In case we have loops to care about, do not propagate arguments of
1341 loop closed ssa phi nodes. */
1343 && is_gimple_reg (def)
1344 && TREE_CODE (use) == SSA_NAME
1345 && a->loop_father != b->loop_father)
1346 may_replace_uses = false;
1348 if (!may_replace_uses)
1350 gcc_assert (is_gimple_reg (def));
1352 /* Note that just emitting the copies is fine -- there is no problem
1353 with ordering of phi nodes. This is because A is the single
1354 predecessor of B, therefore results of the phi nodes cannot
1355 appear as arguments of the phi nodes. */
1356 copy = build2 (MODIFY_EXPR, void_type_node, def, use);
1357 bsi_insert_after (&bsi, copy, BSI_NEW_STMT);
1358 SET_PHI_RESULT (phi, NULL_TREE);
1359 SSA_NAME_DEF_STMT (def) = copy;
1362 replace_uses_by (def, use);
1364 remove_phi_node (phi, NULL);
1367 /* Ensure that B follows A. */
1368 move_block_after (b, a);
1370 gcc_assert (single_succ_edge (a)->flags & EDGE_FALLTHRU);
1371 gcc_assert (!last_stmt (a) || !stmt_ends_bb_p (last_stmt (a)));
1373 /* Remove labels from B and set bb_for_stmt to A for other statements. */
1374 for (bsi = bsi_start (b); !bsi_end_p (bsi);)
1376 if (TREE_CODE (bsi_stmt (bsi)) == LABEL_EXPR)
1378 tree label = bsi_stmt (bsi);
1380 bsi_remove (&bsi, false);
1381 /* Now that we can thread computed gotos, we might have
1382 a situation where we have a forced label in block B
1383 However, the label at the start of block B might still be
1384 used in other ways (think about the runtime checking for
1385 Fortran assigned gotos). So we can not just delete the
1386 label. Instead we move the label to the start of block A. */
1387 if (FORCED_LABEL (LABEL_EXPR_LABEL (label)))
1389 block_stmt_iterator dest_bsi = bsi_start (a);
1390 bsi_insert_before (&dest_bsi, label, BSI_NEW_STMT);
1395 set_bb_for_stmt (bsi_stmt (bsi), a);
1400 /* Merge the chains. */
1401 last = tsi_last (a->stmt_list);
1402 tsi_link_after (&last, b->stmt_list, TSI_NEW_STMT);
1403 b->stmt_list = NULL;
1407 /* Return the one of two successors of BB that is not reachable by a
1408 reached by a complex edge, if there is one. Else, return BB. We use
1409 this in optimizations that use post-dominators for their heuristics,
1410 to catch the cases in C++ where function calls are involved. */
1413 single_noncomplex_succ (basic_block bb)
1416 if (EDGE_COUNT (bb->succs) != 2)
1419 e0 = EDGE_SUCC (bb, 0);
1420 e1 = EDGE_SUCC (bb, 1);
1421 if (e0->flags & EDGE_COMPLEX)
1423 if (e1->flags & EDGE_COMPLEX)
1431 /* Walk the function tree removing unnecessary statements.
1433 * Empty statement nodes are removed
1435 * Unnecessary TRY_FINALLY and TRY_CATCH blocks are removed
1437 * Unnecessary COND_EXPRs are removed
1439 * Some unnecessary BIND_EXPRs are removed
1441 Clearly more work could be done. The trick is doing the analysis
1442 and removal fast enough to be a net improvement in compile times.
1444 Note that when we remove a control structure such as a COND_EXPR
1445 BIND_EXPR, or TRY block, we will need to repeat this optimization pass
1446 to ensure we eliminate all the useless code. */
1457 static void remove_useless_stmts_1 (tree *, struct rus_data *);
1460 remove_useless_stmts_warn_notreached (tree stmt)
1462 if (EXPR_HAS_LOCATION (stmt))
1464 location_t loc = EXPR_LOCATION (stmt);
1465 if (LOCATION_LINE (loc) > 0)
1467 warning (0, "%Hwill never be executed", &loc);
1472 switch (TREE_CODE (stmt))
1474 case STATEMENT_LIST:
1476 tree_stmt_iterator i;
1477 for (i = tsi_start (stmt); !tsi_end_p (i); tsi_next (&i))
1478 if (remove_useless_stmts_warn_notreached (tsi_stmt (i)))
1484 if (remove_useless_stmts_warn_notreached (COND_EXPR_COND (stmt)))
1486 if (remove_useless_stmts_warn_notreached (COND_EXPR_THEN (stmt)))
1488 if (remove_useless_stmts_warn_notreached (COND_EXPR_ELSE (stmt)))
1492 case TRY_FINALLY_EXPR:
1493 case TRY_CATCH_EXPR:
1494 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt, 0)))
1496 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt, 1)))
1501 return remove_useless_stmts_warn_notreached (CATCH_BODY (stmt));
1502 case EH_FILTER_EXPR:
1503 return remove_useless_stmts_warn_notreached (EH_FILTER_FAILURE (stmt));
1505 return remove_useless_stmts_warn_notreached (BIND_EXPR_BLOCK (stmt));
1508 /* Not a live container. */
1516 remove_useless_stmts_cond (tree *stmt_p, struct rus_data *data)
1518 tree then_clause, else_clause, cond;
1519 bool save_has_label, then_has_label, else_has_label;
1521 save_has_label = data->has_label;
1522 data->has_label = false;
1523 data->last_goto = NULL;
1525 remove_useless_stmts_1 (&COND_EXPR_THEN (*stmt_p), data);
1527 then_has_label = data->has_label;
1528 data->has_label = false;
1529 data->last_goto = NULL;
1531 remove_useless_stmts_1 (&COND_EXPR_ELSE (*stmt_p), data);
1533 else_has_label = data->has_label;
1534 data->has_label = save_has_label | then_has_label | else_has_label;
1536 then_clause = COND_EXPR_THEN (*stmt_p);
1537 else_clause = COND_EXPR_ELSE (*stmt_p);
1538 cond = fold (COND_EXPR_COND (*stmt_p));
1540 /* If neither arm does anything at all, we can remove the whole IF. */
1541 if (!TREE_SIDE_EFFECTS (then_clause) && !TREE_SIDE_EFFECTS (else_clause))
1543 *stmt_p = build_empty_stmt ();
1544 data->repeat = true;
1547 /* If there are no reachable statements in an arm, then we can
1548 zap the entire conditional. */
1549 else if (integer_nonzerop (cond) && !else_has_label)
1551 if (warn_notreached)
1552 remove_useless_stmts_warn_notreached (else_clause);
1553 *stmt_p = then_clause;
1554 data->repeat = true;
1556 else if (integer_zerop (cond) && !then_has_label)
1558 if (warn_notreached)
1559 remove_useless_stmts_warn_notreached (then_clause);
1560 *stmt_p = else_clause;
1561 data->repeat = true;
1564 /* Check a couple of simple things on then/else with single stmts. */
1567 tree then_stmt = expr_only (then_clause);
1568 tree else_stmt = expr_only (else_clause);
1570 /* Notice branches to a common destination. */
1571 if (then_stmt && else_stmt
1572 && TREE_CODE (then_stmt) == GOTO_EXPR
1573 && TREE_CODE (else_stmt) == GOTO_EXPR
1574 && (GOTO_DESTINATION (then_stmt) == GOTO_DESTINATION (else_stmt)))
1576 *stmt_p = then_stmt;
1577 data->repeat = true;
1580 /* If the THEN/ELSE clause merely assigns a value to a variable or
1581 parameter which is already known to contain that value, then
1582 remove the useless THEN/ELSE clause. */
1583 else if (TREE_CODE (cond) == VAR_DECL || TREE_CODE (cond) == PARM_DECL)
1586 && TREE_CODE (else_stmt) == MODIFY_EXPR
1587 && TREE_OPERAND (else_stmt, 0) == cond
1588 && integer_zerop (TREE_OPERAND (else_stmt, 1)))
1589 COND_EXPR_ELSE (*stmt_p) = alloc_stmt_list ();
1591 else if ((TREE_CODE (cond) == EQ_EXPR || TREE_CODE (cond) == NE_EXPR)
1592 && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL
1593 || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL)
1594 && TREE_CONSTANT (TREE_OPERAND (cond, 1)))
1596 tree stmt = (TREE_CODE (cond) == EQ_EXPR
1597 ? then_stmt : else_stmt);
1598 tree *location = (TREE_CODE (cond) == EQ_EXPR
1599 ? &COND_EXPR_THEN (*stmt_p)
1600 : &COND_EXPR_ELSE (*stmt_p));
1603 && TREE_CODE (stmt) == MODIFY_EXPR
1604 && TREE_OPERAND (stmt, 0) == TREE_OPERAND (cond, 0)
1605 && TREE_OPERAND (stmt, 1) == TREE_OPERAND (cond, 1))
1606 *location = alloc_stmt_list ();
1610 /* Protect GOTOs in the arm of COND_EXPRs from being removed. They
1611 would be re-introduced during lowering. */
1612 data->last_goto = NULL;
1617 remove_useless_stmts_tf (tree *stmt_p, struct rus_data *data)
1619 bool save_may_branch, save_may_throw;
1620 bool this_may_branch, this_may_throw;
1622 /* Collect may_branch and may_throw information for the body only. */
1623 save_may_branch = data->may_branch;
1624 save_may_throw = data->may_throw;
1625 data->may_branch = false;
1626 data->may_throw = false;
1627 data->last_goto = NULL;
1629 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 0), data);
1631 this_may_branch = data->may_branch;
1632 this_may_throw = data->may_throw;
1633 data->may_branch |= save_may_branch;
1634 data->may_throw |= save_may_throw;
1635 data->last_goto = NULL;
1637 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 1), data);
1639 /* If the body is empty, then we can emit the FINALLY block without
1640 the enclosing TRY_FINALLY_EXPR. */
1641 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 0)))
1643 *stmt_p = TREE_OPERAND (*stmt_p, 1);
1644 data->repeat = true;
1647 /* If the handler is empty, then we can emit the TRY block without
1648 the enclosing TRY_FINALLY_EXPR. */
1649 else if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 1)))
1651 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1652 data->repeat = true;
1655 /* If the body neither throws, nor branches, then we can safely
1656 string the TRY and FINALLY blocks together. */
1657 else if (!this_may_branch && !this_may_throw)
1659 tree stmt = *stmt_p;
1660 *stmt_p = TREE_OPERAND (stmt, 0);
1661 append_to_statement_list (TREE_OPERAND (stmt, 1), stmt_p);
1662 data->repeat = true;
1668 remove_useless_stmts_tc (tree *stmt_p, struct rus_data *data)
1670 bool save_may_throw, this_may_throw;
1671 tree_stmt_iterator i;
1674 /* Collect may_throw information for the body only. */
1675 save_may_throw = data->may_throw;
1676 data->may_throw = false;
1677 data->last_goto = NULL;
1679 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 0), data);
1681 this_may_throw = data->may_throw;
1682 data->may_throw = save_may_throw;
1684 /* If the body cannot throw, then we can drop the entire TRY_CATCH_EXPR. */
1685 if (!this_may_throw)
1687 if (warn_notreached)
1688 remove_useless_stmts_warn_notreached (TREE_OPERAND (*stmt_p, 1));
1689 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1690 data->repeat = true;
1694 /* Process the catch clause specially. We may be able to tell that
1695 no exceptions propagate past this point. */
1697 this_may_throw = true;
1698 i = tsi_start (TREE_OPERAND (*stmt_p, 1));
1699 stmt = tsi_stmt (i);
1700 data->last_goto = NULL;
1702 switch (TREE_CODE (stmt))
1705 for (; !tsi_end_p (i); tsi_next (&i))
1707 stmt = tsi_stmt (i);
1708 /* If we catch all exceptions, then the body does not
1709 propagate exceptions past this point. */
1710 if (CATCH_TYPES (stmt) == NULL)
1711 this_may_throw = false;
1712 data->last_goto = NULL;
1713 remove_useless_stmts_1 (&CATCH_BODY (stmt), data);
1717 case EH_FILTER_EXPR:
1718 if (EH_FILTER_MUST_NOT_THROW (stmt))
1719 this_may_throw = false;
1720 else if (EH_FILTER_TYPES (stmt) == NULL)
1721 this_may_throw = false;
1722 remove_useless_stmts_1 (&EH_FILTER_FAILURE (stmt), data);
1726 /* Otherwise this is a cleanup. */
1727 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 1), data);
1729 /* If the cleanup is empty, then we can emit the TRY block without
1730 the enclosing TRY_CATCH_EXPR. */
1731 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 1)))
1733 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1734 data->repeat = true;
1738 data->may_throw |= this_may_throw;
1743 remove_useless_stmts_bind (tree *stmt_p, struct rus_data *data)
1747 /* First remove anything underneath the BIND_EXPR. */
1748 remove_useless_stmts_1 (&BIND_EXPR_BODY (*stmt_p), data);
1750 /* If the BIND_EXPR has no variables, then we can pull everything
1751 up one level and remove the BIND_EXPR, unless this is the toplevel
1752 BIND_EXPR for the current function or an inlined function.
1754 When this situation occurs we will want to apply this
1755 optimization again. */
1756 block = BIND_EXPR_BLOCK (*stmt_p);
1757 if (BIND_EXPR_VARS (*stmt_p) == NULL_TREE
1758 && *stmt_p != DECL_SAVED_TREE (current_function_decl)
1760 || ! BLOCK_ABSTRACT_ORIGIN (block)
1761 || (TREE_CODE (BLOCK_ABSTRACT_ORIGIN (block))
1764 *stmt_p = BIND_EXPR_BODY (*stmt_p);
1765 data->repeat = true;
1771 remove_useless_stmts_goto (tree *stmt_p, struct rus_data *data)
1773 tree dest = GOTO_DESTINATION (*stmt_p);
1775 data->may_branch = true;
1776 data->last_goto = NULL;
1778 /* Record the last goto expr, so that we can delete it if unnecessary. */
1779 if (TREE_CODE (dest) == LABEL_DECL)
1780 data->last_goto = stmt_p;
1785 remove_useless_stmts_label (tree *stmt_p, struct rus_data *data)
1787 tree label = LABEL_EXPR_LABEL (*stmt_p);
1789 data->has_label = true;
1791 /* We do want to jump across non-local label receiver code. */
1792 if (DECL_NONLOCAL (label))
1793 data->last_goto = NULL;
1795 else if (data->last_goto && GOTO_DESTINATION (*data->last_goto) == label)
1797 *data->last_goto = build_empty_stmt ();
1798 data->repeat = true;
1801 /* ??? Add something here to delete unused labels. */
1805 /* If the function is "const" or "pure", then clear TREE_SIDE_EFFECTS on its
1806 decl. This allows us to eliminate redundant or useless
1807 calls to "const" functions.
1809 Gimplifier already does the same operation, but we may notice functions
1810 being const and pure once their calls has been gimplified, so we need
1811 to update the flag. */
1814 update_call_expr_flags (tree call)
1816 tree decl = get_callee_fndecl (call);
1819 if (call_expr_flags (call) & (ECF_CONST | ECF_PURE))
1820 TREE_SIDE_EFFECTS (call) = 0;
1821 if (TREE_NOTHROW (decl))
1822 TREE_NOTHROW (call) = 1;
1826 /* T is CALL_EXPR. Set current_function_calls_* flags. */
1829 notice_special_calls (tree t)
1831 int flags = call_expr_flags (t);
1833 if (flags & ECF_MAY_BE_ALLOCA)
1834 current_function_calls_alloca = true;
1835 if (flags & ECF_RETURNS_TWICE)
1836 current_function_calls_setjmp = true;
1840 /* Clear flags set by notice_special_calls. Used by dead code removal
1841 to update the flags. */
1844 clear_special_calls (void)
1846 current_function_calls_alloca = false;
1847 current_function_calls_setjmp = false;
1852 remove_useless_stmts_1 (tree *tp, struct rus_data *data)
1856 switch (TREE_CODE (t))
1859 remove_useless_stmts_cond (tp, data);
1862 case TRY_FINALLY_EXPR:
1863 remove_useless_stmts_tf (tp, data);
1866 case TRY_CATCH_EXPR:
1867 remove_useless_stmts_tc (tp, data);
1871 remove_useless_stmts_bind (tp, data);
1875 remove_useless_stmts_goto (tp, data);
1879 remove_useless_stmts_label (tp, data);
1884 data->last_goto = NULL;
1885 data->may_branch = true;
1890 data->last_goto = NULL;
1891 notice_special_calls (t);
1892 update_call_expr_flags (t);
1893 if (tree_could_throw_p (t))
1894 data->may_throw = true;
1898 data->last_goto = NULL;
1900 op = get_call_expr_in (t);
1903 update_call_expr_flags (op);
1904 notice_special_calls (op);
1906 if (tree_could_throw_p (t))
1907 data->may_throw = true;
1910 case STATEMENT_LIST:
1912 tree_stmt_iterator i = tsi_start (t);
1913 while (!tsi_end_p (i))
1916 if (IS_EMPTY_STMT (t))
1922 remove_useless_stmts_1 (tsi_stmt_ptr (i), data);
1925 if (TREE_CODE (t) == STATEMENT_LIST)
1927 tsi_link_before (&i, t, TSI_SAME_STMT);
1937 data->last_goto = NULL;
1941 data->last_goto = NULL;
1947 remove_useless_stmts (void)
1949 struct rus_data data;
1951 clear_special_calls ();
1955 memset (&data, 0, sizeof (data));
1956 remove_useless_stmts_1 (&DECL_SAVED_TREE (current_function_decl), &data);
1958 while (data.repeat);
1962 struct tree_opt_pass pass_remove_useless_stmts =
1964 "useless", /* name */
1966 remove_useless_stmts, /* execute */
1969 0, /* static_pass_number */
1971 PROP_gimple_any, /* properties_required */
1972 0, /* properties_provided */
1973 0, /* properties_destroyed */
1974 0, /* todo_flags_start */
1975 TODO_dump_func, /* todo_flags_finish */
1979 /* Remove PHI nodes associated with basic block BB and all edges out of BB. */
1982 remove_phi_nodes_and_edges_for_unreachable_block (basic_block bb)
1986 /* Since this block is no longer reachable, we can just delete all
1987 of its PHI nodes. */
1988 phi = phi_nodes (bb);
1991 tree next = PHI_CHAIN (phi);
1992 remove_phi_node (phi, NULL_TREE);
1996 /* Remove edges to BB's successors. */
1997 while (EDGE_COUNT (bb->succs) > 0)
1998 remove_edge (EDGE_SUCC (bb, 0));
2002 /* Remove statements of basic block BB. */
2005 remove_bb (basic_block bb)
2007 block_stmt_iterator i;
2008 #ifdef USE_MAPPED_LOCATION
2009 source_location loc = UNKNOWN_LOCATION;
2011 source_locus loc = 0;
2016 fprintf (dump_file, "Removing basic block %d\n", bb->index);
2017 if (dump_flags & TDF_DETAILS)
2019 dump_bb (bb, dump_file, 0);
2020 fprintf (dump_file, "\n");
2024 /* If we remove the header or the latch of a loop, mark the loop for
2025 removal by setting its header and latch to NULL. */
2028 struct loop *loop = bb->loop_father;
2030 if (loop->latch == bb
2031 || loop->header == bb)
2034 loop->header = NULL;
2036 /* Also clean up the information associated with the loop. Updating
2037 it would waste time. More importantly, it may refer to ssa
2038 names that were defined in other removed basic block -- these
2039 ssa names are now removed and invalid. */
2040 free_numbers_of_iterations_estimates_loop (loop);
2044 /* Remove all the instructions in the block. */
2045 for (i = bsi_start (bb); !bsi_end_p (i);)
2047 tree stmt = bsi_stmt (i);
2048 if (TREE_CODE (stmt) == LABEL_EXPR
2049 && (FORCED_LABEL (LABEL_EXPR_LABEL (stmt))
2050 || DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt))))
2053 block_stmt_iterator new_bsi;
2055 /* A non-reachable non-local label may still be referenced.
2056 But it no longer needs to carry the extra semantics of
2058 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)))
2060 DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)) = 0;
2061 FORCED_LABEL (LABEL_EXPR_LABEL (stmt)) = 1;
2064 new_bb = bb->prev_bb;
2065 new_bsi = bsi_start (new_bb);
2066 bsi_remove (&i, false);
2067 bsi_insert_before (&new_bsi, stmt, BSI_NEW_STMT);
2071 /* Release SSA definitions if we are in SSA. Note that we
2072 may be called when not in SSA. For example,
2073 final_cleanup calls this function via
2074 cleanup_tree_cfg. */
2076 release_defs (stmt);
2078 bsi_remove (&i, true);
2081 /* Don't warn for removed gotos. Gotos are often removed due to
2082 jump threading, thus resulting in bogus warnings. Not great,
2083 since this way we lose warnings for gotos in the original
2084 program that are indeed unreachable. */
2085 if (TREE_CODE (stmt) != GOTO_EXPR && EXPR_HAS_LOCATION (stmt) && !loc)
2087 #ifdef USE_MAPPED_LOCATION
2088 if (EXPR_HAS_LOCATION (stmt))
2089 loc = EXPR_LOCATION (stmt);
2092 t = EXPR_LOCUS (stmt);
2093 if (t && LOCATION_LINE (*t) > 0)
2099 /* If requested, give a warning that the first statement in the
2100 block is unreachable. We walk statements backwards in the
2101 loop above, so the last statement we process is the first statement
2103 #ifdef USE_MAPPED_LOCATION
2104 if (loc > BUILTINS_LOCATION)
2105 warning (OPT_Wunreachable_code, "%Hwill never be executed", &loc);
2108 warning (OPT_Wunreachable_code, "%Hwill never be executed", loc);
2111 remove_phi_nodes_and_edges_for_unreachable_block (bb);
2115 /* Given a basic block BB ending with COND_EXPR or SWITCH_EXPR, and a
2116 predicate VAL, return the edge that will be taken out of the block.
2117 If VAL does not match a unique edge, NULL is returned. */
2120 find_taken_edge (basic_block bb, tree val)
2124 stmt = last_stmt (bb);
2127 gcc_assert (is_ctrl_stmt (stmt));
2130 if (! is_gimple_min_invariant (val))
2133 if (TREE_CODE (stmt) == COND_EXPR)
2134 return find_taken_edge_cond_expr (bb, val);
2136 if (TREE_CODE (stmt) == SWITCH_EXPR)
2137 return find_taken_edge_switch_expr (bb, val);
2139 if (computed_goto_p (stmt))
2140 return find_taken_edge_computed_goto (bb, TREE_OPERAND( val, 0));
2145 /* Given a constant value VAL and the entry block BB to a GOTO_EXPR
2146 statement, determine which of the outgoing edges will be taken out of the
2147 block. Return NULL if either edge may be taken. */
2150 find_taken_edge_computed_goto (basic_block bb, tree val)
2155 dest = label_to_block (val);
2158 e = find_edge (bb, dest);
2159 gcc_assert (e != NULL);
2165 /* Given a constant value VAL and the entry block BB to a COND_EXPR
2166 statement, determine which of the two edges will be taken out of the
2167 block. Return NULL if either edge may be taken. */
2170 find_taken_edge_cond_expr (basic_block bb, tree val)
2172 edge true_edge, false_edge;
2174 extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
2176 gcc_assert (TREE_CODE (val) == INTEGER_CST);
2177 return (zero_p (val) ? false_edge : true_edge);
2180 /* Given an INTEGER_CST VAL and the entry block BB to a SWITCH_EXPR
2181 statement, determine which edge will be taken out of the block. Return
2182 NULL if any edge may be taken. */
2185 find_taken_edge_switch_expr (basic_block bb, tree val)
2187 tree switch_expr, taken_case;
2188 basic_block dest_bb;
2191 switch_expr = last_stmt (bb);
2192 taken_case = find_case_label_for_value (switch_expr, val);
2193 dest_bb = label_to_block (CASE_LABEL (taken_case));
2195 e = find_edge (bb, dest_bb);
2201 /* Return the CASE_LABEL_EXPR that SWITCH_EXPR will take for VAL.
2202 We can make optimal use here of the fact that the case labels are
2203 sorted: We can do a binary search for a case matching VAL. */
2206 find_case_label_for_value (tree switch_expr, tree val)
2208 tree vec = SWITCH_LABELS (switch_expr);
2209 size_t low, high, n = TREE_VEC_LENGTH (vec);
2210 tree default_case = TREE_VEC_ELT (vec, n - 1);
2212 for (low = -1, high = n - 1; high - low > 1; )
2214 size_t i = (high + low) / 2;
2215 tree t = TREE_VEC_ELT (vec, i);
2218 /* Cache the result of comparing CASE_LOW and val. */
2219 cmp = tree_int_cst_compare (CASE_LOW (t), val);
2226 if (CASE_HIGH (t) == NULL)
2228 /* A singe-valued case label. */
2234 /* A case range. We can only handle integer ranges. */
2235 if (cmp <= 0 && tree_int_cst_compare (CASE_HIGH (t), val) >= 0)
2240 return default_case;
2246 /*---------------------------------------------------------------------------
2248 ---------------------------------------------------------------------------*/
2250 /* Dump tree-specific information of block BB to file OUTF. */
2253 tree_dump_bb (basic_block bb, FILE *outf, int indent)
2255 dump_generic_bb (outf, bb, indent, TDF_VOPS);
2259 /* Dump a basic block on stderr. */
2262 debug_tree_bb (basic_block bb)
2264 dump_bb (bb, stderr, 0);
2268 /* Dump basic block with index N on stderr. */
2271 debug_tree_bb_n (int n)
2273 debug_tree_bb (BASIC_BLOCK (n));
2274 return BASIC_BLOCK (n);
2278 /* Dump the CFG on stderr.
2280 FLAGS are the same used by the tree dumping functions
2281 (see TDF_* in tree.h). */
2284 debug_tree_cfg (int flags)
2286 dump_tree_cfg (stderr, flags);
2290 /* Dump the program showing basic block boundaries on the given FILE.
2292 FLAGS are the same used by the tree dumping functions (see TDF_* in
2296 dump_tree_cfg (FILE *file, int flags)
2298 if (flags & TDF_DETAILS)
2300 const char *funcname
2301 = lang_hooks.decl_printable_name (current_function_decl, 2);
2304 fprintf (file, ";; Function %s\n\n", funcname);
2305 fprintf (file, ";; \n%d basic blocks, %d edges, last basic block %d.\n\n",
2306 n_basic_blocks, n_edges, last_basic_block);
2308 brief_dump_cfg (file);
2309 fprintf (file, "\n");
2312 if (flags & TDF_STATS)
2313 dump_cfg_stats (file);
2315 dump_function_to_file (current_function_decl, file, flags | TDF_BLOCKS);
2319 /* Dump CFG statistics on FILE. */
2322 dump_cfg_stats (FILE *file)
2324 static long max_num_merged_labels = 0;
2325 unsigned long size, total = 0;
2328 const char * const fmt_str = "%-30s%-13s%12s\n";
2329 const char * const fmt_str_1 = "%-30s%13d%11lu%c\n";
2330 const char * const fmt_str_2 = "%-30s%13ld%11lu%c\n";
2331 const char * const fmt_str_3 = "%-43s%11lu%c\n";
2332 const char *funcname
2333 = lang_hooks.decl_printable_name (current_function_decl, 2);
2336 fprintf (file, "\nCFG Statistics for %s\n\n", funcname);
2338 fprintf (file, "---------------------------------------------------------\n");
2339 fprintf (file, fmt_str, "", " Number of ", "Memory");
2340 fprintf (file, fmt_str, "", " instances ", "used ");
2341 fprintf (file, "---------------------------------------------------------\n");
2343 size = n_basic_blocks * sizeof (struct basic_block_def);
2345 fprintf (file, fmt_str_1, "Basic blocks", n_basic_blocks,
2346 SCALE (size), LABEL (size));
2350 num_edges += EDGE_COUNT (bb->succs);
2351 size = num_edges * sizeof (struct edge_def);
2353 fprintf (file, fmt_str_2, "Edges", num_edges, SCALE (size), LABEL (size));
2355 fprintf (file, "---------------------------------------------------------\n");
2356 fprintf (file, fmt_str_3, "Total memory used by CFG data", SCALE (total),
2358 fprintf (file, "---------------------------------------------------------\n");
2359 fprintf (file, "\n");
2361 if (cfg_stats.num_merged_labels > max_num_merged_labels)
2362 max_num_merged_labels = cfg_stats.num_merged_labels;
2364 fprintf (file, "Coalesced label blocks: %ld (Max so far: %ld)\n",
2365 cfg_stats.num_merged_labels, max_num_merged_labels);
2367 fprintf (file, "\n");
2371 /* Dump CFG statistics on stderr. Keep extern so that it's always
2372 linked in the final executable. */
2375 debug_cfg_stats (void)
2377 dump_cfg_stats (stderr);
2381 /* Dump the flowgraph to a .vcg FILE. */
2384 tree_cfg2vcg (FILE *file)
2389 const char *funcname
2390 = lang_hooks.decl_printable_name (current_function_decl, 2);
2392 /* Write the file header. */
2393 fprintf (file, "graph: { title: \"%s\"\n", funcname);
2394 fprintf (file, "node: { title: \"ENTRY\" label: \"ENTRY\" }\n");
2395 fprintf (file, "node: { title: \"EXIT\" label: \"EXIT\" }\n");
2397 /* Write blocks and edges. */
2398 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
2400 fprintf (file, "edge: { sourcename: \"ENTRY\" targetname: \"%d\"",
2403 if (e->flags & EDGE_FAKE)
2404 fprintf (file, " linestyle: dotted priority: 10");
2406 fprintf (file, " linestyle: solid priority: 100");
2408 fprintf (file, " }\n");
2414 enum tree_code head_code, end_code;
2415 const char *head_name, *end_name;
2418 tree first = first_stmt (bb);
2419 tree last = last_stmt (bb);
2423 head_code = TREE_CODE (first);
2424 head_name = tree_code_name[head_code];
2425 head_line = get_lineno (first);
2428 head_name = "no-statement";
2432 end_code = TREE_CODE (last);
2433 end_name = tree_code_name[end_code];
2434 end_line = get_lineno (last);
2437 end_name = "no-statement";
2439 fprintf (file, "node: { title: \"%d\" label: \"#%d\\n%s (%d)\\n%s (%d)\"}\n",
2440 bb->index, bb->index, head_name, head_line, end_name,
2443 FOR_EACH_EDGE (e, ei, bb->succs)
2445 if (e->dest == EXIT_BLOCK_PTR)
2446 fprintf (file, "edge: { sourcename: \"%d\" targetname: \"EXIT\"", bb->index);
2448 fprintf (file, "edge: { sourcename: \"%d\" targetname: \"%d\"", bb->index, e->dest->index);
2450 if (e->flags & EDGE_FAKE)
2451 fprintf (file, " priority: 10 linestyle: dotted");
2453 fprintf (file, " priority: 100 linestyle: solid");
2455 fprintf (file, " }\n");
2458 if (bb->next_bb != EXIT_BLOCK_PTR)
2462 fputs ("}\n\n", file);
2467 /*---------------------------------------------------------------------------
2468 Miscellaneous helpers
2469 ---------------------------------------------------------------------------*/
2471 /* Return true if T represents a stmt that always transfers control. */
2474 is_ctrl_stmt (tree t)
2476 return (TREE_CODE (t) == COND_EXPR
2477 || TREE_CODE (t) == SWITCH_EXPR
2478 || TREE_CODE (t) == GOTO_EXPR
2479 || TREE_CODE (t) == RETURN_EXPR
2480 || TREE_CODE (t) == RESX_EXPR);
2484 /* Return true if T is a statement that may alter the flow of control
2485 (e.g., a call to a non-returning function). */
2488 is_ctrl_altering_stmt (tree t)
2493 call = get_call_expr_in (t);
2496 /* A non-pure/const CALL_EXPR alters flow control if the current
2497 function has nonlocal labels. */
2498 if (TREE_SIDE_EFFECTS (call) && current_function_has_nonlocal_label)
2501 /* A CALL_EXPR also alters control flow if it does not return. */
2502 if (call_expr_flags (call) & ECF_NORETURN)
2506 /* If a statement can throw, it alters control flow. */
2507 return tree_can_throw_internal (t);
2511 /* Return true if T is a computed goto. */
2514 computed_goto_p (tree t)
2516 return (TREE_CODE (t) == GOTO_EXPR
2517 && TREE_CODE (GOTO_DESTINATION (t)) != LABEL_DECL);
2521 /* Checks whether EXPR is a simple local goto. */
2524 simple_goto_p (tree expr)
2526 return (TREE_CODE (expr) == GOTO_EXPR
2527 && TREE_CODE (GOTO_DESTINATION (expr)) == LABEL_DECL);
2531 /* Return true if T should start a new basic block. PREV_T is the
2532 statement preceding T. It is used when T is a label or a case label.
2533 Labels should only start a new basic block if their previous statement
2534 wasn't a label. Otherwise, sequence of labels would generate
2535 unnecessary basic blocks that only contain a single label. */
2538 stmt_starts_bb_p (tree t, tree prev_t)
2543 /* LABEL_EXPRs start a new basic block only if the preceding
2544 statement wasn't a label of the same type. This prevents the
2545 creation of consecutive blocks that have nothing but a single
2547 if (TREE_CODE (t) == LABEL_EXPR)
2549 /* Nonlocal and computed GOTO targets always start a new block. */
2550 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (t))
2551 || FORCED_LABEL (LABEL_EXPR_LABEL (t)))
2554 if (prev_t && TREE_CODE (prev_t) == LABEL_EXPR)
2556 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (prev_t)))
2559 cfg_stats.num_merged_labels++;
2570 /* Return true if T should end a basic block. */
2573 stmt_ends_bb_p (tree t)
2575 return is_ctrl_stmt (t) || is_ctrl_altering_stmt (t);
2579 /* Add gotos that used to be represented implicitly in the CFG. */
2582 disband_implicit_edges (void)
2585 block_stmt_iterator last;
2592 last = bsi_last (bb);
2593 stmt = last_stmt (bb);
2595 if (stmt && TREE_CODE (stmt) == COND_EXPR)
2597 /* Remove superfluous gotos from COND_EXPR branches. Moved
2598 from cfg_remove_useless_stmts here since it violates the
2599 invariants for tree--cfg correspondence and thus fits better
2600 here where we do it anyway. */
2601 e = find_edge (bb, bb->next_bb);
2604 if (e->flags & EDGE_TRUE_VALUE)
2605 COND_EXPR_THEN (stmt) = build_empty_stmt ();
2606 else if (e->flags & EDGE_FALSE_VALUE)
2607 COND_EXPR_ELSE (stmt) = build_empty_stmt ();
2610 e->flags |= EDGE_FALLTHRU;
2616 if (stmt && TREE_CODE (stmt) == RETURN_EXPR)
2618 /* Remove the RETURN_EXPR if we may fall though to the exit
2620 gcc_assert (single_succ_p (bb));
2621 gcc_assert (single_succ (bb) == EXIT_BLOCK_PTR);
2623 if (bb->next_bb == EXIT_BLOCK_PTR
2624 && !TREE_OPERAND (stmt, 0))
2626 bsi_remove (&last, true);
2627 single_succ_edge (bb)->flags |= EDGE_FALLTHRU;
2632 /* There can be no fallthru edge if the last statement is a control
2634 if (stmt && is_ctrl_stmt (stmt))
2637 /* Find a fallthru edge and emit the goto if necessary. */
2638 FOR_EACH_EDGE (e, ei, bb->succs)
2639 if (e->flags & EDGE_FALLTHRU)
2642 if (!e || e->dest == bb->next_bb)
2645 gcc_assert (e->dest != EXIT_BLOCK_PTR);
2646 label = tree_block_label (e->dest);
2648 stmt = build1 (GOTO_EXPR, void_type_node, label);
2649 #ifdef USE_MAPPED_LOCATION
2650 SET_EXPR_LOCATION (stmt, e->goto_locus);
2652 SET_EXPR_LOCUS (stmt, e->goto_locus);
2654 bsi_insert_after (&last, stmt, BSI_NEW_STMT);
2655 e->flags &= ~EDGE_FALLTHRU;
2659 /* Remove block annotations and other datastructures. */
2662 delete_tree_cfg_annotations (void)
2664 label_to_block_map = NULL;
2668 /* Return the first statement in basic block BB. */
2671 first_stmt (basic_block bb)
2673 block_stmt_iterator i = bsi_start (bb);
2674 return !bsi_end_p (i) ? bsi_stmt (i) : NULL_TREE;
2678 /* Return the last statement in basic block BB. */
2681 last_stmt (basic_block bb)
2683 block_stmt_iterator b = bsi_last (bb);
2684 return !bsi_end_p (b) ? bsi_stmt (b) : NULL_TREE;
2688 /* Return a pointer to the last statement in block BB. */
2691 last_stmt_ptr (basic_block bb)
2693 block_stmt_iterator last = bsi_last (bb);
2694 return !bsi_end_p (last) ? bsi_stmt_ptr (last) : NULL;
2698 /* Return the last statement of an otherwise empty block. Return NULL
2699 if the block is totally empty, or if it contains more than one
2703 last_and_only_stmt (basic_block bb)
2705 block_stmt_iterator i = bsi_last (bb);
2711 last = bsi_stmt (i);
2716 /* Empty statements should no longer appear in the instruction stream.
2717 Everything that might have appeared before should be deleted by
2718 remove_useless_stmts, and the optimizers should just bsi_remove
2719 instead of smashing with build_empty_stmt.
2721 Thus the only thing that should appear here in a block containing
2722 one executable statement is a label. */
2723 prev = bsi_stmt (i);
2724 if (TREE_CODE (prev) == LABEL_EXPR)
2731 /* Mark BB as the basic block holding statement T. */
2734 set_bb_for_stmt (tree t, basic_block bb)
2736 if (TREE_CODE (t) == PHI_NODE)
2738 else if (TREE_CODE (t) == STATEMENT_LIST)
2740 tree_stmt_iterator i;
2741 for (i = tsi_start (t); !tsi_end_p (i); tsi_next (&i))
2742 set_bb_for_stmt (tsi_stmt (i), bb);
2746 stmt_ann_t ann = get_stmt_ann (t);
2749 /* If the statement is a label, add the label to block-to-labels map
2750 so that we can speed up edge creation for GOTO_EXPRs. */
2751 if (TREE_CODE (t) == LABEL_EXPR)
2755 t = LABEL_EXPR_LABEL (t);
2756 uid = LABEL_DECL_UID (t);
2759 unsigned old_len = VEC_length (basic_block, label_to_block_map);
2760 LABEL_DECL_UID (t) = uid = cfun->last_label_uid++;
2761 if (old_len <= (unsigned) uid)
2764 unsigned new_len = 3 * uid / 2;
2766 VEC_safe_grow (basic_block, gc, label_to_block_map,
2768 addr = VEC_address (basic_block, label_to_block_map);
2769 memset (&addr[old_len],
2770 0, sizeof (basic_block) * (new_len - old_len));
2774 /* We're moving an existing label. Make sure that we've
2775 removed it from the old block. */
2777 || !VEC_index (basic_block, label_to_block_map, uid));
2778 VEC_replace (basic_block, label_to_block_map, uid, bb);
2783 /* Finds iterator for STMT. */
2785 extern block_stmt_iterator
2786 bsi_for_stmt (tree stmt)
2788 block_stmt_iterator bsi;
2790 for (bsi = bsi_start (bb_for_stmt (stmt)); !bsi_end_p (bsi); bsi_next (&bsi))
2791 if (bsi_stmt (bsi) == stmt)
2797 /* Mark statement T as modified, and update it. */
2799 update_modified_stmts (tree t)
2801 if (TREE_CODE (t) == STATEMENT_LIST)
2803 tree_stmt_iterator i;
2805 for (i = tsi_start (t); !tsi_end_p (i); tsi_next (&i))
2807 stmt = tsi_stmt (i);
2808 update_stmt_if_modified (stmt);
2812 update_stmt_if_modified (t);
2815 /* Insert statement (or statement list) T before the statement
2816 pointed-to by iterator I. M specifies how to update iterator I
2817 after insertion (see enum bsi_iterator_update). */
2820 bsi_insert_before (block_stmt_iterator *i, tree t, enum bsi_iterator_update m)
2822 set_bb_for_stmt (t, i->bb);
2823 update_modified_stmts (t);
2824 tsi_link_before (&i->tsi, t, m);
2828 /* Insert statement (or statement list) T after the statement
2829 pointed-to by iterator I. M specifies how to update iterator I
2830 after insertion (see enum bsi_iterator_update). */
2833 bsi_insert_after (block_stmt_iterator *i, tree t, enum bsi_iterator_update m)
2835 set_bb_for_stmt (t, i->bb);
2836 update_modified_stmts (t);
2837 tsi_link_after (&i->tsi, t, m);
2841 /* Remove the statement pointed to by iterator I. The iterator is updated
2842 to the next statement.
2844 When REMOVE_EH_INFO is true we remove the statement pointed to by
2845 iterator I from the EH tables. Otherwise we do not modify the EH
2848 Generally, REMOVE_EH_INFO should be true when the statement is going to
2849 be removed from the IL and not reinserted elsewhere. */
2852 bsi_remove (block_stmt_iterator *i, bool remove_eh_info)
2854 tree t = bsi_stmt (*i);
2855 set_bb_for_stmt (t, NULL);
2856 delink_stmt_imm_use (t);
2857 tsi_delink (&i->tsi);
2858 mark_stmt_modified (t);
2860 remove_stmt_from_eh_region (t);
2864 /* Move the statement at FROM so it comes right after the statement at TO. */
2867 bsi_move_after (block_stmt_iterator *from, block_stmt_iterator *to)
2869 tree stmt = bsi_stmt (*from);
2870 bsi_remove (from, false);
2871 bsi_insert_after (to, stmt, BSI_SAME_STMT);
2875 /* Move the statement at FROM so it comes right before the statement at TO. */
2878 bsi_move_before (block_stmt_iterator *from, block_stmt_iterator *to)
2880 tree stmt = bsi_stmt (*from);
2881 bsi_remove (from, false);
2882 bsi_insert_before (to, stmt, BSI_SAME_STMT);
2886 /* Move the statement at FROM to the end of basic block BB. */
2889 bsi_move_to_bb_end (block_stmt_iterator *from, basic_block bb)
2891 block_stmt_iterator last = bsi_last (bb);
2893 /* Have to check bsi_end_p because it could be an empty block. */
2894 if (!bsi_end_p (last) && is_ctrl_stmt (bsi_stmt (last)))
2895 bsi_move_before (from, &last);
2897 bsi_move_after (from, &last);
2901 /* Replace the contents of the statement pointed to by iterator BSI
2902 with STMT. If UPDATE_EH_INFO is true, the exception handling
2903 information of the original statement is moved to the new statement. */
2907 bsi_replace (const block_stmt_iterator *bsi, tree stmt, bool update_eh_info)
2910 tree orig_stmt = bsi_stmt (*bsi);
2912 SET_EXPR_LOCUS (stmt, EXPR_LOCUS (orig_stmt));
2913 set_bb_for_stmt (stmt, bsi->bb);
2915 /* Preserve EH region information from the original statement, if
2916 requested by the caller. */
2919 eh_region = lookup_stmt_eh_region (orig_stmt);
2922 remove_stmt_from_eh_region (orig_stmt);
2923 add_stmt_to_eh_region (stmt, eh_region);
2927 delink_stmt_imm_use (orig_stmt);
2928 *bsi_stmt_ptr (*bsi) = stmt;
2929 mark_stmt_modified (stmt);
2930 update_modified_stmts (stmt);
2934 /* Insert the statement pointed-to by BSI into edge E. Every attempt
2935 is made to place the statement in an existing basic block, but
2936 sometimes that isn't possible. When it isn't possible, the edge is
2937 split and the statement is added to the new block.
2939 In all cases, the returned *BSI points to the correct location. The
2940 return value is true if insertion should be done after the location,
2941 or false if it should be done before the location. If new basic block
2942 has to be created, it is stored in *NEW_BB. */
2945 tree_find_edge_insert_loc (edge e, block_stmt_iterator *bsi,
2946 basic_block *new_bb)
2948 basic_block dest, src;
2954 /* If the destination has one predecessor which has no PHI nodes,
2955 insert there. Except for the exit block.
2957 The requirement for no PHI nodes could be relaxed. Basically we
2958 would have to examine the PHIs to prove that none of them used
2959 the value set by the statement we want to insert on E. That
2960 hardly seems worth the effort. */
2961 if (single_pred_p (dest)
2962 && ! phi_nodes (dest)
2963 && dest != EXIT_BLOCK_PTR)
2965 *bsi = bsi_start (dest);
2966 if (bsi_end_p (*bsi))
2969 /* Make sure we insert after any leading labels. */
2970 tmp = bsi_stmt (*bsi);
2971 while (TREE_CODE (tmp) == LABEL_EXPR)
2974 if (bsi_end_p (*bsi))
2976 tmp = bsi_stmt (*bsi);
2979 if (bsi_end_p (*bsi))
2981 *bsi = bsi_last (dest);
2988 /* If the source has one successor, the edge is not abnormal and
2989 the last statement does not end a basic block, insert there.
2990 Except for the entry block. */
2992 if ((e->flags & EDGE_ABNORMAL) == 0
2993 && single_succ_p (src)
2994 && src != ENTRY_BLOCK_PTR)
2996 *bsi = bsi_last (src);
2997 if (bsi_end_p (*bsi))
3000 tmp = bsi_stmt (*bsi);
3001 if (!stmt_ends_bb_p (tmp))
3004 /* Insert code just before returning the value. We may need to decompose
3005 the return in the case it contains non-trivial operand. */
3006 if (TREE_CODE (tmp) == RETURN_EXPR)
3008 tree op = TREE_OPERAND (tmp, 0);
3009 if (op && !is_gimple_val (op))
3011 gcc_assert (TREE_CODE (op) == MODIFY_EXPR);
3012 bsi_insert_before (bsi, op, BSI_NEW_STMT);
3013 TREE_OPERAND (tmp, 0) = TREE_OPERAND (op, 0);
3020 /* Otherwise, create a new basic block, and split this edge. */
3021 dest = split_edge (e);
3024 e = single_pred_edge (dest);
3029 /* This routine will commit all pending edge insertions, creating any new
3030 basic blocks which are necessary. */
3033 bsi_commit_edge_inserts (void)
3039 bsi_commit_one_edge_insert (single_succ_edge (ENTRY_BLOCK_PTR), NULL);
3042 FOR_EACH_EDGE (e, ei, bb->succs)
3043 bsi_commit_one_edge_insert (e, NULL);
3047 /* Commit insertions pending at edge E. If a new block is created, set NEW_BB
3048 to this block, otherwise set it to NULL. */
3051 bsi_commit_one_edge_insert (edge e, basic_block *new_bb)
3055 if (PENDING_STMT (e))
3057 block_stmt_iterator bsi;
3058 tree stmt = PENDING_STMT (e);
3060 PENDING_STMT (e) = NULL_TREE;
3062 if (tree_find_edge_insert_loc (e, &bsi, new_bb))
3063 bsi_insert_after (&bsi, stmt, BSI_NEW_STMT);
3065 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
3070 /* Add STMT to the pending list of edge E. No actual insertion is
3071 made until a call to bsi_commit_edge_inserts () is made. */
3074 bsi_insert_on_edge (edge e, tree stmt)
3076 append_to_statement_list (stmt, &PENDING_STMT (e));
3079 /* Similar to bsi_insert_on_edge+bsi_commit_edge_inserts. If a new
3080 block has to be created, it is returned. */
3083 bsi_insert_on_edge_immediate (edge e, tree stmt)
3085 block_stmt_iterator bsi;
3086 basic_block new_bb = NULL;
3088 gcc_assert (!PENDING_STMT (e));
3090 if (tree_find_edge_insert_loc (e, &bsi, &new_bb))
3091 bsi_insert_after (&bsi, stmt, BSI_NEW_STMT);
3093 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
3098 /*---------------------------------------------------------------------------
3099 Tree specific functions for CFG manipulation
3100 ---------------------------------------------------------------------------*/
3102 /* Reinstall those PHI arguments queued in OLD_EDGE to NEW_EDGE. */
3105 reinstall_phi_args (edge new_edge, edge old_edge)
3109 if (!PENDING_STMT (old_edge))
3112 for (var = PENDING_STMT (old_edge), phi = phi_nodes (new_edge->dest);
3114 var = TREE_CHAIN (var), phi = PHI_CHAIN (phi))
3116 tree result = TREE_PURPOSE (var);
3117 tree arg = TREE_VALUE (var);
3119 gcc_assert (result == PHI_RESULT (phi));
3121 add_phi_arg (phi, arg, new_edge);
3124 PENDING_STMT (old_edge) = NULL;
3127 /* Returns the basic block after that the new basic block created
3128 by splitting edge EDGE_IN should be placed. Tries to keep the new block
3129 near its "logical" location. This is of most help to humans looking
3130 at debugging dumps. */
3133 split_edge_bb_loc (edge edge_in)
3135 basic_block dest = edge_in->dest;
3137 if (dest->prev_bb && find_edge (dest->prev_bb, dest))
3138 return edge_in->src;
3140 return dest->prev_bb;
3143 /* Split a (typically critical) edge EDGE_IN. Return the new block.
3144 Abort on abnormal edges. */
3147 tree_split_edge (edge edge_in)
3149 basic_block new_bb, after_bb, dest, src;
3152 /* Abnormal edges cannot be split. */
3153 gcc_assert (!(edge_in->flags & EDGE_ABNORMAL));
3156 dest = edge_in->dest;
3158 after_bb = split_edge_bb_loc (edge_in);
3160 new_bb = create_empty_bb (after_bb);
3161 new_bb->frequency = EDGE_FREQUENCY (edge_in);
3162 new_bb->count = edge_in->count;
3163 new_edge = make_edge (new_bb, dest, EDGE_FALLTHRU);
3164 new_edge->probability = REG_BR_PROB_BASE;
3165 new_edge->count = edge_in->count;
3167 e = redirect_edge_and_branch (edge_in, new_bb);
3169 reinstall_phi_args (new_edge, e);
3175 /* Return true when BB has label LABEL in it. */
3178 has_label_p (basic_block bb, tree label)
3180 block_stmt_iterator bsi;
3182 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3184 tree stmt = bsi_stmt (bsi);
3186 if (TREE_CODE (stmt) != LABEL_EXPR)
3188 if (LABEL_EXPR_LABEL (stmt) == label)
3195 /* Callback for walk_tree, check that all elements with address taken are
3196 properly noticed as such. The DATA is an int* that is 1 if TP was seen
3197 inside a PHI node. */
3200 verify_expr (tree *tp, int *walk_subtrees, void *data ATTRIBUTE_UNUSED)
3203 bool in_phi = (data != NULL);
3208 /* Check operand N for being valid GIMPLE and give error MSG if not. */
3209 #define CHECK_OP(N, MSG) \
3210 do { if (!is_gimple_val (TREE_OPERAND (t, N))) \
3211 { error (MSG); return TREE_OPERAND (t, N); }} while (0)
3213 switch (TREE_CODE (t))
3216 if (SSA_NAME_IN_FREE_LIST (t))
3218 error ("SSA name in freelist but still referenced");
3224 x = fold (ASSERT_EXPR_COND (t));
3225 if (x == boolean_false_node)
3227 error ("ASSERT_EXPR with an always-false condition");
3233 x = TREE_OPERAND (t, 0);
3234 if (TREE_CODE (x) == BIT_FIELD_REF
3235 && is_gimple_reg (TREE_OPERAND (x, 0)))
3237 error ("GIMPLE register modified with BIT_FIELD_REF");
3246 bool old_side_effects;
3249 bool new_side_effects;
3251 /* ??? tree-ssa-alias.c may have overlooked dead PHI nodes, missing
3252 dead PHIs that take the address of something. But if the PHI
3253 result is dead, the fact that it takes the address of anything
3254 is irrelevant. Because we can not tell from here if a PHI result
3255 is dead, we just skip this check for PHIs altogether. This means
3256 we may be missing "valid" checks, but what can you do?
3257 This was PR19217. */
3261 old_invariant = TREE_INVARIANT (t);
3262 old_constant = TREE_CONSTANT (t);
3263 old_side_effects = TREE_SIDE_EFFECTS (t);
3265 recompute_tree_invariant_for_addr_expr (t);
3266 new_invariant = TREE_INVARIANT (t);
3267 new_side_effects = TREE_SIDE_EFFECTS (t);
3268 new_constant = TREE_CONSTANT (t);
3270 if (old_invariant != new_invariant)
3272 error ("invariant not recomputed when ADDR_EXPR changed");
3276 if (old_constant != new_constant)
3278 error ("constant not recomputed when ADDR_EXPR changed");
3281 if (old_side_effects != new_side_effects)
3283 error ("side effects not recomputed when ADDR_EXPR changed");
3287 /* Skip any references (they will be checked when we recurse down the
3288 tree) and ensure that any variable used as a prefix is marked
3290 for (x = TREE_OPERAND (t, 0);
3291 handled_component_p (x);
3292 x = TREE_OPERAND (x, 0))
3295 if (TREE_CODE (x) != VAR_DECL && TREE_CODE (x) != PARM_DECL)
3297 if (!TREE_ADDRESSABLE (x))
3299 error ("address taken, but ADDRESSABLE bit not set");
3306 x = COND_EXPR_COND (t);
3307 if (TREE_CODE (TREE_TYPE (x)) != BOOLEAN_TYPE)
3309 error ("non-boolean used in condition");
3312 if (!is_gimple_condexpr (x))
3314 error ("invalid conditional operand");
3321 case FIX_TRUNC_EXPR:
3323 case FIX_FLOOR_EXPR:
3324 case FIX_ROUND_EXPR:
3329 case NON_LVALUE_EXPR:
3330 case TRUTH_NOT_EXPR:
3331 CHECK_OP (0, "invalid operand to unary operator");
3338 case ARRAY_RANGE_REF:
3340 case VIEW_CONVERT_EXPR:
3341 /* We have a nest of references. Verify that each of the operands
3342 that determine where to reference is either a constant or a variable,
3343 verify that the base is valid, and then show we've already checked
3345 while (handled_component_p (t))
3347 if (TREE_CODE (t) == COMPONENT_REF && TREE_OPERAND (t, 2))
3348 CHECK_OP (2, "invalid COMPONENT_REF offset operator");
3349 else if (TREE_CODE (t) == ARRAY_REF
3350 || TREE_CODE (t) == ARRAY_RANGE_REF)
3352 CHECK_OP (1, "invalid array index");
3353 if (TREE_OPERAND (t, 2))
3354 CHECK_OP (2, "invalid array lower bound");
3355 if (TREE_OPERAND (t, 3))
3356 CHECK_OP (3, "invalid array stride");
3358 else if (TREE_CODE (t) == BIT_FIELD_REF)
3360 CHECK_OP (1, "invalid operand to BIT_FIELD_REF");
3361 CHECK_OP (2, "invalid operand to BIT_FIELD_REF");
3364 t = TREE_OPERAND (t, 0);
3367 if (!CONSTANT_CLASS_P (t) && !is_gimple_lvalue (t))
3369 error ("invalid reference prefix");
3381 case UNORDERED_EXPR:
3392 case TRUNC_DIV_EXPR:
3394 case FLOOR_DIV_EXPR:
3395 case ROUND_DIV_EXPR:
3396 case TRUNC_MOD_EXPR:
3398 case FLOOR_MOD_EXPR:
3399 case ROUND_MOD_EXPR:
3401 case EXACT_DIV_EXPR:
3411 CHECK_OP (0, "invalid operand to binary operator");
3412 CHECK_OP (1, "invalid operand to binary operator");
3424 /* Verify STMT, return true if STMT is not in GIMPLE form.
3425 TODO: Implement type checking. */
3428 verify_stmt (tree stmt, bool last_in_block)
3432 if (!is_gimple_stmt (stmt))
3434 error ("is not a valid GIMPLE statement");
3438 addr = walk_tree (&stmt, verify_expr, NULL, NULL);
3441 debug_generic_stmt (addr);
3445 /* If the statement is marked as part of an EH region, then it is
3446 expected that the statement could throw. Verify that when we
3447 have optimizations that simplify statements such that we prove
3448 that they cannot throw, that we update other data structures
3450 if (lookup_stmt_eh_region (stmt) >= 0)
3452 if (!tree_could_throw_p (stmt))
3454 error ("statement marked for throw, but doesn%'t");
3457 if (!last_in_block && tree_can_throw_internal (stmt))
3459 error ("statement marked for throw in middle of block");
3467 debug_generic_stmt (stmt);
3472 /* Return true when the T can be shared. */
3475 tree_node_can_be_shared (tree t)
3477 if (IS_TYPE_OR_DECL_P (t)
3478 /* We check for constants explicitly since they are not considered
3479 gimple invariants if they overflowed. */
3480 || CONSTANT_CLASS_P (t)
3481 || is_gimple_min_invariant (t)
3482 || TREE_CODE (t) == SSA_NAME
3483 || t == error_mark_node)
3486 if (TREE_CODE (t) == CASE_LABEL_EXPR)
3489 while (((TREE_CODE (t) == ARRAY_REF || TREE_CODE (t) == ARRAY_RANGE_REF)
3490 /* We check for constants explicitly since they are not considered
3491 gimple invariants if they overflowed. */
3492 && (CONSTANT_CLASS_P (TREE_OPERAND (t, 1))
3493 || is_gimple_min_invariant (TREE_OPERAND (t, 1))))
3494 || (TREE_CODE (t) == COMPONENT_REF
3495 || TREE_CODE (t) == REALPART_EXPR
3496 || TREE_CODE (t) == IMAGPART_EXPR))
3497 t = TREE_OPERAND (t, 0);
3506 /* Called via walk_trees. Verify tree sharing. */
3509 verify_node_sharing (tree * tp, int *walk_subtrees, void *data)
3511 htab_t htab = (htab_t) data;
3514 if (tree_node_can_be_shared (*tp))
3516 *walk_subtrees = false;
3520 slot = htab_find_slot (htab, *tp, INSERT);
3522 return (tree) *slot;
3529 /* Verify the GIMPLE statement chain. */
3535 block_stmt_iterator bsi;
3540 timevar_push (TV_TREE_STMT_VERIFY);
3541 htab = htab_create (37, htab_hash_pointer, htab_eq_pointer, NULL);
3548 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
3550 int phi_num_args = PHI_NUM_ARGS (phi);
3552 if (bb_for_stmt (phi) != bb)
3554 error ("bb_for_stmt (phi) is set to a wrong basic block");
3558 for (i = 0; i < phi_num_args; i++)
3560 tree t = PHI_ARG_DEF (phi, i);
3563 /* Addressable variables do have SSA_NAMEs but they
3564 are not considered gimple values. */
3565 if (TREE_CODE (t) != SSA_NAME
3566 && TREE_CODE (t) != FUNCTION_DECL
3567 && !is_gimple_val (t))
3569 error ("PHI def is not a GIMPLE value");
3570 debug_generic_stmt (phi);
3571 debug_generic_stmt (t);
3575 addr = walk_tree (&t, verify_expr, (void *) 1, NULL);
3578 debug_generic_stmt (addr);
3582 addr = walk_tree (&t, verify_node_sharing, htab, NULL);
3585 error ("incorrect sharing of tree nodes");
3586 debug_generic_stmt (phi);
3587 debug_generic_stmt (addr);
3593 for (bsi = bsi_start (bb); !bsi_end_p (bsi); )
3595 tree stmt = bsi_stmt (bsi);
3597 if (bb_for_stmt (stmt) != bb)
3599 error ("bb_for_stmt (stmt) is set to a wrong basic block");
3604 err |= verify_stmt (stmt, bsi_end_p (bsi));
3605 addr = walk_tree (&stmt, verify_node_sharing, htab, NULL);
3608 error ("incorrect sharing of tree nodes");
3609 debug_generic_stmt (stmt);
3610 debug_generic_stmt (addr);
3617 internal_error ("verify_stmts failed");
3620 timevar_pop (TV_TREE_STMT_VERIFY);
3624 /* Verifies that the flow information is OK. */
3627 tree_verify_flow_info (void)
3631 block_stmt_iterator bsi;
3636 if (ENTRY_BLOCK_PTR->stmt_list)
3638 error ("ENTRY_BLOCK has a statement list associated with it");
3642 if (EXIT_BLOCK_PTR->stmt_list)
3644 error ("EXIT_BLOCK has a statement list associated with it");
3648 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
3649 if (e->flags & EDGE_FALLTHRU)
3651 error ("fallthru to exit from bb %d", e->src->index);
3657 bool found_ctrl_stmt = false;
3661 /* Skip labels on the start of basic block. */
3662 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3664 tree prev_stmt = stmt;
3666 stmt = bsi_stmt (bsi);
3668 if (TREE_CODE (stmt) != LABEL_EXPR)
3671 if (prev_stmt && DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)))
3673 error ("nonlocal label %s is not first "
3674 "in a sequence of labels in bb %d",
3675 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt))),
3680 if (label_to_block (LABEL_EXPR_LABEL (stmt)) != bb)
3682 error ("label %s to block does not match in bb %d",
3683 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt))),
3688 if (decl_function_context (LABEL_EXPR_LABEL (stmt))
3689 != current_function_decl)
3691 error ("label %s has incorrect context in bb %d",
3692 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt))),
3698 /* Verify that body of basic block BB is free of control flow. */
3699 for (; !bsi_end_p (bsi); bsi_next (&bsi))
3701 tree stmt = bsi_stmt (bsi);
3703 if (found_ctrl_stmt)
3705 error ("control flow in the middle of basic block %d",
3710 if (stmt_ends_bb_p (stmt))
3711 found_ctrl_stmt = true;
3713 if (TREE_CODE (stmt) == LABEL_EXPR)
3715 error ("label %s in the middle of basic block %d",
3716 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt))),
3721 bsi = bsi_last (bb);
3722 if (bsi_end_p (bsi))
3725 stmt = bsi_stmt (bsi);
3727 err |= verify_eh_edges (stmt);
3729 if (is_ctrl_stmt (stmt))
3731 FOR_EACH_EDGE (e, ei, bb->succs)
3732 if (e->flags & EDGE_FALLTHRU)
3734 error ("fallthru edge after a control statement in bb %d",
3740 switch (TREE_CODE (stmt))
3746 if (TREE_CODE (COND_EXPR_THEN (stmt)) != GOTO_EXPR
3747 || TREE_CODE (COND_EXPR_ELSE (stmt)) != GOTO_EXPR)
3749 error ("structured COND_EXPR at the end of bb %d", bb->index);
3753 extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
3755 if (!true_edge || !false_edge
3756 || !(true_edge->flags & EDGE_TRUE_VALUE)
3757 || !(false_edge->flags & EDGE_FALSE_VALUE)
3758 || (true_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL))
3759 || (false_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL))
3760 || EDGE_COUNT (bb->succs) >= 3)
3762 error ("wrong outgoing edge flags at end of bb %d",
3767 if (!has_label_p (true_edge->dest,
3768 GOTO_DESTINATION (COND_EXPR_THEN (stmt))))
3770 error ("%<then%> label does not match edge at end of bb %d",
3775 if (!has_label_p (false_edge->dest,
3776 GOTO_DESTINATION (COND_EXPR_ELSE (stmt))))
3778 error ("%<else%> label does not match edge at end of bb %d",
3786 if (simple_goto_p (stmt))
3788 error ("explicit goto at end of bb %d", bb->index);
3793 /* FIXME. We should double check that the labels in the
3794 destination blocks have their address taken. */
3795 FOR_EACH_EDGE (e, ei, bb->succs)
3796 if ((e->flags & (EDGE_FALLTHRU | EDGE_TRUE_VALUE
3797 | EDGE_FALSE_VALUE))
3798 || !(e->flags & EDGE_ABNORMAL))
3800 error ("wrong outgoing edge flags at end of bb %d",
3808 if (!single_succ_p (bb)
3809 || (single_succ_edge (bb)->flags
3810 & (EDGE_FALLTHRU | EDGE_ABNORMAL
3811 | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
3813 error ("wrong outgoing edge flags at end of bb %d", bb->index);
3816 if (single_succ (bb) != EXIT_BLOCK_PTR)
3818 error ("return edge does not point to exit in bb %d",
3831 vec = SWITCH_LABELS (stmt);
3832 n = TREE_VEC_LENGTH (vec);
3834 /* Mark all the destination basic blocks. */
3835 for (i = 0; i < n; ++i)
3837 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
3838 basic_block label_bb = label_to_block (lab);
3840 gcc_assert (!label_bb->aux || label_bb->aux == (void *)1);
3841 label_bb->aux = (void *)1;
3844 /* Verify that the case labels are sorted. */
3845 prev = TREE_VEC_ELT (vec, 0);
3846 for (i = 1; i < n - 1; ++i)
3848 tree c = TREE_VEC_ELT (vec, i);
3851 error ("found default case not at end of case vector");
3855 if (! tree_int_cst_lt (CASE_LOW (prev), CASE_LOW (c)))
3857 error ("case labels not sorted:");
3858 print_generic_expr (stderr, prev, 0);
3859 fprintf (stderr," is greater than ");
3860 print_generic_expr (stderr, c, 0);
3861 fprintf (stderr," but comes before it.\n");
3866 if (CASE_LOW (TREE_VEC_ELT (vec, n - 1)))
3868 error ("no default case found at end of case vector");
3872 FOR_EACH_EDGE (e, ei, bb->succs)
3876 error ("extra outgoing edge %d->%d",
3877 bb->index, e->dest->index);
3880 e->dest->aux = (void *)2;
3881 if ((e->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL
3882 | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
3884 error ("wrong outgoing edge flags at end of bb %d",
3890 /* Check that we have all of them. */
3891 for (i = 0; i < n; ++i)
3893 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
3894 basic_block label_bb = label_to_block (lab);
3896 if (label_bb->aux != (void *)2)
3898 error ("missing edge %i->%i",
3899 bb->index, label_bb->index);
3904 FOR_EACH_EDGE (e, ei, bb->succs)
3905 e->dest->aux = (void *)0;
3912 if (dom_computed[CDI_DOMINATORS] >= DOM_NO_FAST_QUERY)
3913 verify_dominators (CDI_DOMINATORS);
3919 /* Updates phi nodes after creating a forwarder block joined
3920 by edge FALLTHRU. */
3923 tree_make_forwarder_block (edge fallthru)
3927 basic_block dummy, bb;
3928 tree phi, new_phi, var;
3930 dummy = fallthru->src;
3931 bb = fallthru->dest;
3933 if (single_pred_p (bb))
3936 /* If we redirected a branch we must create new phi nodes at the
3938 for (phi = phi_nodes (dummy); phi; phi = PHI_CHAIN (phi))
3940 var = PHI_RESULT (phi);
3941 new_phi = create_phi_node (var, bb);
3942 SSA_NAME_DEF_STMT (var) = new_phi;
3943 SET_PHI_RESULT (phi, make_ssa_name (SSA_NAME_VAR (var), phi));
3944 add_phi_arg (new_phi, PHI_RESULT (phi), fallthru);
3947 /* Ensure that the PHI node chain is in the same order. */
3948 set_phi_nodes (bb, phi_reverse (phi_nodes (bb)));
3950 /* Add the arguments we have stored on edges. */
3951 FOR_EACH_EDGE (e, ei, bb->preds)
3956 flush_pending_stmts (e);
3961 /* Return a non-special label in the head of basic block BLOCK.
3962 Create one if it doesn't exist. */
3965 tree_block_label (basic_block bb)
3967 block_stmt_iterator i, s = bsi_start (bb);
3971 for (i = s; !bsi_end_p (i); first = false, bsi_next (&i))
3973 stmt = bsi_stmt (i);
3974 if (TREE_CODE (stmt) != LABEL_EXPR)
3976 label = LABEL_EXPR_LABEL (stmt);
3977 if (!DECL_NONLOCAL (label))
3980 bsi_move_before (&i, &s);
3985 label = create_artificial_label ();
3986 stmt = build1 (LABEL_EXPR, void_type_node, label);
3987 bsi_insert_before (&s, stmt, BSI_NEW_STMT);
3992 /* Attempt to perform edge redirection by replacing a possibly complex
3993 jump instruction by a goto or by removing the jump completely.
3994 This can apply only if all edges now point to the same block. The
3995 parameters and return values are equivalent to
3996 redirect_edge_and_branch. */
3999 tree_try_redirect_by_replacing_jump (edge e, basic_block target)
4001 basic_block src = e->src;
4002 block_stmt_iterator b;
4005 /* We can replace or remove a complex jump only when we have exactly
4007 if (EDGE_COUNT (src->succs) != 2
4008 /* Verify that all targets will be TARGET. Specifically, the
4009 edge that is not E must also go to TARGET. */
4010 || EDGE_SUCC (src, EDGE_SUCC (src, 0) == e)->dest != target)
4016 stmt = bsi_stmt (b);
4018 if (TREE_CODE (stmt) == COND_EXPR
4019 || TREE_CODE (stmt) == SWITCH_EXPR)
4021 bsi_remove (&b, true);
4022 e = ssa_redirect_edge (e, target);
4023 e->flags = EDGE_FALLTHRU;
4031 /* Redirect E to DEST. Return NULL on failure. Otherwise, return the
4032 edge representing the redirected branch. */
4035 tree_redirect_edge_and_branch (edge e, basic_block dest)
4037 basic_block bb = e->src;
4038 block_stmt_iterator bsi;
4042 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
4045 if (e->src != ENTRY_BLOCK_PTR
4046 && (ret = tree_try_redirect_by_replacing_jump (e, dest)))
4049 if (e->dest == dest)
4052 label = tree_block_label (dest);
4054 bsi = bsi_last (bb);
4055 stmt = bsi_end_p (bsi) ? NULL : bsi_stmt (bsi);
4057 switch (stmt ? TREE_CODE (stmt) : ERROR_MARK)
4060 stmt = (e->flags & EDGE_TRUE_VALUE
4061 ? COND_EXPR_THEN (stmt)
4062 : COND_EXPR_ELSE (stmt));
4063 GOTO_DESTINATION (stmt) = label;
4067 /* No non-abnormal edges should lead from a non-simple goto, and
4068 simple ones should be represented implicitly. */
4073 tree cases = get_cases_for_edge (e, stmt);
4075 /* If we have a list of cases associated with E, then use it
4076 as it's a lot faster than walking the entire case vector. */
4079 edge e2 = find_edge (e->src, dest);
4086 CASE_LABEL (cases) = label;
4087 cases = TREE_CHAIN (cases);
4090 /* If there was already an edge in the CFG, then we need
4091 to move all the cases associated with E to E2. */
4094 tree cases2 = get_cases_for_edge (e2, stmt);
4096 TREE_CHAIN (last) = TREE_CHAIN (cases2);
4097 TREE_CHAIN (cases2) = first;
4102 tree vec = SWITCH_LABELS (stmt);
4103 size_t i, n = TREE_VEC_LENGTH (vec);
4105 for (i = 0; i < n; i++)
4107 tree elt = TREE_VEC_ELT (vec, i);
4109 if (label_to_block (CASE_LABEL (elt)) == e->dest)
4110 CASE_LABEL (elt) = label;
4118 bsi_remove (&bsi, true);
4119 e->flags |= EDGE_FALLTHRU;
4123 /* Otherwise it must be a fallthru edge, and we don't need to
4124 do anything besides redirecting it. */
4125 gcc_assert (e->flags & EDGE_FALLTHRU);
4129 /* Update/insert PHI nodes as necessary. */
4131 /* Now update the edges in the CFG. */
4132 e = ssa_redirect_edge (e, dest);
4138 /* Simple wrapper, as we can always redirect fallthru edges. */
4141 tree_redirect_edge_and_branch_force (edge e, basic_block dest)
4143 e = tree_redirect_edge_and_branch (e, dest);
4150 /* Splits basic block BB after statement STMT (but at least after the
4151 labels). If STMT is NULL, BB is split just after the labels. */
4154 tree_split_block (basic_block bb, void *stmt)
4156 block_stmt_iterator bsi, bsi_tgt;
4162 new_bb = create_empty_bb (bb);
4164 /* Redirect the outgoing edges. */
4165 new_bb->succs = bb->succs;
4167 FOR_EACH_EDGE (e, ei, new_bb->succs)
4170 if (stmt && TREE_CODE ((tree) stmt) == LABEL_EXPR)
4173 /* Move everything from BSI to the new basic block. */
4174 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4176 act = bsi_stmt (bsi);
4177 if (TREE_CODE (act) == LABEL_EXPR)
4190 bsi_tgt = bsi_start (new_bb);
4191 while (!bsi_end_p (bsi))
4193 act = bsi_stmt (bsi);
4194 bsi_remove (&bsi, false);
4195 bsi_insert_after (&bsi_tgt, act, BSI_NEW_STMT);
4202 /* Moves basic block BB after block AFTER. */
4205 tree_move_block_after (basic_block bb, basic_block after)
4207 if (bb->prev_bb == after)
4211 link_block (bb, after);
4217 /* Return true if basic_block can be duplicated. */
4220 tree_can_duplicate_bb_p (basic_block bb ATTRIBUTE_UNUSED)
4226 /* Create a duplicate of the basic block BB. NOTE: This does not
4227 preserve SSA form. */
4230 tree_duplicate_bb (basic_block bb)
4233 block_stmt_iterator bsi, bsi_tgt;
4236 new_bb = create_empty_bb (EXIT_BLOCK_PTR->prev_bb);
4238 /* Copy the PHI nodes. We ignore PHI node arguments here because
4239 the incoming edges have not been setup yet. */
4240 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
4242 tree copy = create_phi_node (PHI_RESULT (phi), new_bb);
4243 create_new_def_for (PHI_RESULT (copy), copy, PHI_RESULT_PTR (copy));
4246 /* Keep the chain of PHI nodes in the same order so that they can be
4247 updated by ssa_redirect_edge. */
4248 set_phi_nodes (new_bb, phi_reverse (phi_nodes (new_bb)));
4250 bsi_tgt = bsi_start (new_bb);
4251 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4253 def_operand_p def_p;
4254 ssa_op_iter op_iter;
4258 stmt = bsi_stmt (bsi);
4259 if (TREE_CODE (stmt) == LABEL_EXPR)
4262 /* Create a new copy of STMT and duplicate STMT's virtual
4264 copy = unshare_expr (stmt);
4265 bsi_insert_after (&bsi_tgt, copy, BSI_NEW_STMT);
4266 copy_virtual_operands (copy, stmt);
4267 region = lookup_stmt_eh_region (stmt);
4269 add_stmt_to_eh_region (copy, region);
4271 /* Create new names for all the definitions created by COPY and
4272 add replacement mappings for each new name. */
4273 FOR_EACH_SSA_DEF_OPERAND (def_p, copy, op_iter, SSA_OP_ALL_DEFS)
4274 create_new_def_for (DEF_FROM_PTR (def_p), copy, def_p);
4281 /* Basic block BB_COPY was created by code duplication. Add phi node
4282 arguments for edges going out of BB_COPY. The blocks that were
4283 duplicated have BB_DUPLICATED set. */
4286 add_phi_args_after_copy_bb (basic_block bb_copy)
4288 basic_block bb, dest;
4291 tree phi, phi_copy, phi_next, def;
4293 bb = get_bb_original (bb_copy);
4295 FOR_EACH_EDGE (e_copy, ei, bb_copy->succs)
4297 if (!phi_nodes (e_copy->dest))
4300 if (e_copy->dest->flags & BB_DUPLICATED)
4301 dest = get_bb_original (e_copy->dest);
4303 dest = e_copy->dest;
4305 e = find_edge (bb, dest);
4308 /* During loop unrolling the target of the latch edge is copied.
4309 In this case we are not looking for edge to dest, but to
4310 duplicated block whose original was dest. */
4311 FOR_EACH_EDGE (e, ei, bb->succs)
4312 if ((e->dest->flags & BB_DUPLICATED)
4313 && get_bb_original (e->dest) == dest)
4316 gcc_assert (e != NULL);
4319 for (phi = phi_nodes (e->dest), phi_copy = phi_nodes (e_copy->dest);
4321 phi = phi_next, phi_copy = PHI_CHAIN (phi_copy))
4323 phi_next = PHI_CHAIN (phi);
4324 def = PHI_ARG_DEF_FROM_EDGE (phi, e);
4325 add_phi_arg (phi_copy, def, e_copy);
4330 /* Blocks in REGION_COPY array of length N_REGION were created by
4331 duplication of basic blocks. Add phi node arguments for edges
4332 going from these blocks. */
4335 add_phi_args_after_copy (basic_block *region_copy, unsigned n_region)
4339 for (i = 0; i < n_region; i++)
4340 region_copy[i]->flags |= BB_DUPLICATED;
4342 for (i = 0; i < n_region; i++)
4343 add_phi_args_after_copy_bb (region_copy[i]);
4345 for (i = 0; i < n_region; i++)
4346 region_copy[i]->flags &= ~BB_DUPLICATED;
4349 /* Duplicates a REGION (set of N_REGION basic blocks) with just a single
4350 important exit edge EXIT. By important we mean that no SSA name defined
4351 inside region is live over the other exit edges of the region. All entry
4352 edges to the region must go to ENTRY->dest. The edge ENTRY is redirected
4353 to the duplicate of the region. SSA form, dominance and loop information
4354 is updated. The new basic blocks are stored to REGION_COPY in the same
4355 order as they had in REGION, provided that REGION_COPY is not NULL.
4356 The function returns false if it is unable to copy the region,
4360 tree_duplicate_sese_region (edge entry, edge exit,
4361 basic_block *region, unsigned n_region,
4362 basic_block *region_copy)
4365 bool free_region_copy = false, copying_header = false;
4366 struct loop *loop = entry->dest->loop_father;
4370 int total_freq = 0, entry_freq = 0;
4371 gcov_type total_count = 0, entry_count = 0;
4373 if (!can_copy_bbs_p (region, n_region))
4376 /* Some sanity checking. Note that we do not check for all possible
4377 missuses of the functions. I.e. if you ask to copy something weird,
4378 it will work, but the state of structures probably will not be
4380 for (i = 0; i < n_region; i++)
4382 /* We do not handle subloops, i.e. all the blocks must belong to the
4384 if (region[i]->loop_father != loop)
4387 if (region[i] != entry->dest
4388 && region[i] == loop->header)
4394 /* In case the function is used for loop header copying (which is the primary
4395 use), ensure that EXIT and its copy will be new latch and entry edges. */
4396 if (loop->header == entry->dest)
4398 copying_header = true;
4399 loop->copy = loop->outer;
4401 if (!dominated_by_p (CDI_DOMINATORS, loop->latch, exit->src))
4404 for (i = 0; i < n_region; i++)
4405 if (region[i] != exit->src
4406 && dominated_by_p (CDI_DOMINATORS, region[i], exit->src))
4412 region_copy = XNEWVEC (basic_block, n_region);
4413 free_region_copy = true;
4416 gcc_assert (!need_ssa_update_p ());
4418 /* Record blocks outside the region that are dominated by something
4420 doms = XNEWVEC (basic_block, n_basic_blocks);
4421 initialize_original_copy_tables ();
4423 n_doms = get_dominated_by_region (CDI_DOMINATORS, region, n_region, doms);
4425 if (entry->dest->count)
4427 total_count = entry->dest->count;
4428 entry_count = entry->count;
4429 /* Fix up corner cases, to avoid division by zero or creation of negative
4431 if (entry_count > total_count)
4432 entry_count = total_count;
4436 total_freq = entry->dest->frequency;
4437 entry_freq = EDGE_FREQUENCY (entry);
4438 /* Fix up corner cases, to avoid division by zero or creation of negative
4440 if (total_freq == 0)
4442 else if (entry_freq > total_freq)
4443 entry_freq = total_freq;
4446 copy_bbs (region, n_region, region_copy, &exit, 1, &exit_copy, loop,
4447 split_edge_bb_loc (entry));
4450 scale_bbs_frequencies_gcov_type (region, n_region,
4451 total_count - entry_count,
4453 scale_bbs_frequencies_gcov_type (region_copy, n_region, entry_count,
4458 scale_bbs_frequencies_int (region, n_region, total_freq - entry_freq,
4460 scale_bbs_frequencies_int (region_copy, n_region, entry_freq, total_freq);
4465 loop->header = exit->dest;
4466 loop->latch = exit->src;
4469 /* Redirect the entry and add the phi node arguments. */
4470 redirected = redirect_edge_and_branch (entry, get_bb_copy (entry->dest));
4471 gcc_assert (redirected != NULL);
4472 flush_pending_stmts (entry);
4474 /* Concerning updating of dominators: We must recount dominators
4475 for entry block and its copy. Anything that is outside of the
4476 region, but was dominated by something inside needs recounting as
4478 set_immediate_dominator (CDI_DOMINATORS, entry->dest, entry->src);
4479 doms[n_doms++] = get_bb_original (entry->dest);
4480 iterate_fix_dominators (CDI_DOMINATORS, doms, n_doms);
4483 /* Add the other PHI node arguments. */
4484 add_phi_args_after_copy (region_copy, n_region);
4486 /* Update the SSA web. */
4487 update_ssa (TODO_update_ssa);
4489 if (free_region_copy)
4492 free_original_copy_tables ();
4497 /* Dump FUNCTION_DECL FN to file FILE using FLAGS (see TDF_* in tree.h) */
4500 dump_function_to_file (tree fn, FILE *file, int flags)
4502 tree arg, vars, var;
4503 bool ignore_topmost_bind = false, any_var = false;
4507 fprintf (file, "%s (", lang_hooks.decl_printable_name (fn, 2));
4509 arg = DECL_ARGUMENTS (fn);
4512 print_generic_expr (file, arg, dump_flags);
4513 if (TREE_CHAIN (arg))
4514 fprintf (file, ", ");
4515 arg = TREE_CHAIN (arg);
4517 fprintf (file, ")\n");
4519 if (flags & TDF_DETAILS)
4520 dump_eh_tree (file, DECL_STRUCT_FUNCTION (fn));
4521 if (flags & TDF_RAW)
4523 dump_node (fn, TDF_SLIM | flags, file);
4527 /* When GIMPLE is lowered, the variables are no longer available in
4528 BIND_EXPRs, so display them separately. */
4529 if (cfun && cfun->decl == fn && cfun->unexpanded_var_list)
4531 ignore_topmost_bind = true;
4533 fprintf (file, "{\n");
4534 for (vars = cfun->unexpanded_var_list; vars; vars = TREE_CHAIN (vars))
4536 var = TREE_VALUE (vars);
4538 print_generic_decl (file, var, flags);
4539 fprintf (file, "\n");
4545 if (cfun && cfun->decl == fn && cfun->cfg && basic_block_info)
4547 /* Make a CFG based dump. */
4548 check_bb_profile (ENTRY_BLOCK_PTR, file);
4549 if (!ignore_topmost_bind)
4550 fprintf (file, "{\n");
4552 if (any_var && n_basic_blocks)
4553 fprintf (file, "\n");
4556 dump_generic_bb (file, bb, 2, flags);
4558 fprintf (file, "}\n");
4559 check_bb_profile (EXIT_BLOCK_PTR, file);
4565 /* Make a tree based dump. */
4566 chain = DECL_SAVED_TREE (fn);
4568 if (TREE_CODE (chain) == BIND_EXPR)
4570 if (ignore_topmost_bind)
4572 chain = BIND_EXPR_BODY (chain);
4580 if (!ignore_topmost_bind)
4581 fprintf (file, "{\n");
4586 fprintf (file, "\n");
4588 print_generic_stmt_indented (file, chain, flags, indent);
4589 if (ignore_topmost_bind)
4590 fprintf (file, "}\n");
4593 fprintf (file, "\n\n");
4597 /* Pretty print of the loops intermediate representation. */
4598 static void print_loop (FILE *, struct loop *, int);
4599 static void print_pred_bbs (FILE *, basic_block bb);
4600 static void print_succ_bbs (FILE *, basic_block bb);
4603 /* Print on FILE the indexes for the predecessors of basic_block BB. */
4606 print_pred_bbs (FILE *file, basic_block bb)
4611 FOR_EACH_EDGE (e, ei, bb->preds)
4612 fprintf (file, "bb_%d ", e->src->index);
4616 /* Print on FILE the indexes for the successors of basic_block BB. */
4619 print_succ_bbs (FILE *file, basic_block bb)
4624 FOR_EACH_EDGE (e, ei, bb->succs)
4625 fprintf (file, "bb_%d ", e->dest->index);
4629 /* Pretty print LOOP on FILE, indented INDENT spaces. */
4632 print_loop (FILE *file, struct loop *loop, int indent)
4640 s_indent = (char *) alloca ((size_t) indent + 1);
4641 memset ((void *) s_indent, ' ', (size_t) indent);
4642 s_indent[indent] = '\0';
4644 /* Print the loop's header. */
4645 fprintf (file, "%sloop_%d\n", s_indent, loop->num);
4647 /* Print the loop's body. */
4648 fprintf (file, "%s{\n", s_indent);
4650 if (bb->loop_father == loop)
4652 /* Print the basic_block's header. */
4653 fprintf (file, "%s bb_%d (preds = {", s_indent, bb->index);
4654 print_pred_bbs (file, bb);
4655 fprintf (file, "}, succs = {");
4656 print_succ_bbs (file, bb);
4657 fprintf (file, "})\n");
4659 /* Print the basic_block's body. */
4660 fprintf (file, "%s {\n", s_indent);
4661 tree_dump_bb (bb, file, indent + 4);
4662 fprintf (file, "%s }\n", s_indent);
4665 print_loop (file, loop->inner, indent + 2);
4666 fprintf (file, "%s}\n", s_indent);
4667 print_loop (file, loop->next, indent);
4671 /* Follow a CFG edge from the entry point of the program, and on entry
4672 of a loop, pretty print the loop structure on FILE. */
4675 print_loop_ir (FILE *file)
4679 bb = BASIC_BLOCK (NUM_FIXED_BLOCKS);
4680 if (bb && bb->loop_father)
4681 print_loop (file, bb->loop_father, 0);
4685 /* Debugging loops structure at tree level. */
4688 debug_loop_ir (void)
4690 print_loop_ir (stderr);
4694 /* Return true if BB ends with a call, possibly followed by some
4695 instructions that must stay with the call. Return false,
4699 tree_block_ends_with_call_p (basic_block bb)
4701 block_stmt_iterator bsi = bsi_last (bb);
4702 return get_call_expr_in (bsi_stmt (bsi)) != NULL;
4706 /* Return true if BB ends with a conditional branch. Return false,
4710 tree_block_ends_with_condjump_p (basic_block bb)
4712 tree stmt = last_stmt (bb);
4713 return (stmt && TREE_CODE (stmt) == COND_EXPR);
4717 /* Return true if we need to add fake edge to exit at statement T.
4718 Helper function for tree_flow_call_edges_add. */
4721 need_fake_edge_p (tree t)
4725 /* NORETURN and LONGJMP calls already have an edge to exit.
4726 CONST and PURE calls do not need one.
4727 We don't currently check for CONST and PURE here, although
4728 it would be a good idea, because those attributes are
4729 figured out from the RTL in mark_constant_function, and
4730 the counter incrementation code from -fprofile-arcs
4731 leads to different results from -fbranch-probabilities. */
4732 call = get_call_expr_in (t);
4734 && !(call_expr_flags (call) & ECF_NORETURN))
4737 if (TREE_CODE (t) == ASM_EXPR
4738 && (ASM_VOLATILE_P (t) || ASM_INPUT_P (t)))
4745 /* Add fake edges to the function exit for any non constant and non
4746 noreturn calls, volatile inline assembly in the bitmap of blocks
4747 specified by BLOCKS or to the whole CFG if BLOCKS is zero. Return
4748 the number of blocks that were split.
4750 The goal is to expose cases in which entering a basic block does
4751 not imply that all subsequent instructions must be executed. */
4754 tree_flow_call_edges_add (sbitmap blocks)
4757 int blocks_split = 0;
4758 int last_bb = last_basic_block;
4759 bool check_last_block = false;
4761 if (n_basic_blocks == NUM_FIXED_BLOCKS)
4765 check_last_block = true;
4767 check_last_block = TEST_BIT (blocks, EXIT_BLOCK_PTR->prev_bb->index);
4769 /* In the last basic block, before epilogue generation, there will be
4770 a fallthru edge to EXIT. Special care is required if the last insn
4771 of the last basic block is a call because make_edge folds duplicate
4772 edges, which would result in the fallthru edge also being marked
4773 fake, which would result in the fallthru edge being removed by
4774 remove_fake_edges, which would result in an invalid CFG.
4776 Moreover, we can't elide the outgoing fake edge, since the block
4777 profiler needs to take this into account in order to solve the minimal
4778 spanning tree in the case that the call doesn't return.
4780 Handle this by adding a dummy instruction in a new last basic block. */
4781 if (check_last_block)
4783 basic_block bb = EXIT_BLOCK_PTR->prev_bb;
4784 block_stmt_iterator bsi = bsi_last (bb);
4786 if (!bsi_end_p (bsi))
4789 if (t && need_fake_edge_p (t))
4793 e = find_edge (bb, EXIT_BLOCK_PTR);
4796 bsi_insert_on_edge (e, build_empty_stmt ());
4797 bsi_commit_edge_inserts ();
4802 /* Now add fake edges to the function exit for any non constant
4803 calls since there is no way that we can determine if they will
4805 for (i = 0; i < last_bb; i++)
4807 basic_block bb = BASIC_BLOCK (i);
4808 block_stmt_iterator bsi;
4809 tree stmt, last_stmt;
4814 if (blocks && !TEST_BIT (blocks, i))
4817 bsi = bsi_last (bb);
4818 if (!bsi_end_p (bsi))
4820 last_stmt = bsi_stmt (bsi);
4823 stmt = bsi_stmt (bsi);
4824 if (need_fake_edge_p (stmt))
4827 /* The handling above of the final block before the
4828 epilogue should be enough to verify that there is
4829 no edge to the exit block in CFG already.
4830 Calling make_edge in such case would cause us to
4831 mark that edge as fake and remove it later. */
4832 #ifdef ENABLE_CHECKING
4833 if (stmt == last_stmt)
4835 e = find_edge (bb, EXIT_BLOCK_PTR);
4836 gcc_assert (e == NULL);
4840 /* Note that the following may create a new basic block
4841 and renumber the existing basic blocks. */
4842 if (stmt != last_stmt)
4844 e = split_block (bb, stmt);
4848 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
4852 while (!bsi_end_p (bsi));
4857 verify_flow_info ();
4859 return blocks_split;
4863 tree_purge_dead_eh_edges (basic_block bb)
4865 bool changed = false;
4868 tree stmt = last_stmt (bb);
4870 if (stmt && tree_can_throw_internal (stmt))
4873 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
4875 if (e->flags & EDGE_EH)
4884 /* Removal of dead EH edges might change dominators of not
4885 just immediate successors. E.g. when bb1 is changed so that
4886 it no longer can throw and bb1->bb3 and bb1->bb4 are dead
4887 eh edges purged by this function in:
4899 idom(bb5) must be recomputed. For now just free the dominance
4902 free_dominance_info (CDI_DOMINATORS);
4908 tree_purge_all_dead_eh_edges (bitmap blocks)
4910 bool changed = false;
4914 EXECUTE_IF_SET_IN_BITMAP (blocks, 0, i, bi)
4916 changed |= tree_purge_dead_eh_edges (BASIC_BLOCK (i));
4922 /* This function is called whenever a new edge is created or
4926 tree_execute_on_growing_pred (edge e)
4928 basic_block bb = e->dest;
4931 reserve_phi_args_for_new_edge (bb);
4934 /* This function is called immediately before edge E is removed from
4935 the edge vector E->dest->preds. */
4938 tree_execute_on_shrinking_pred (edge e)
4940 if (phi_nodes (e->dest))
4941 remove_phi_args (e);
4944 /*---------------------------------------------------------------------------
4945 Helper functions for Loop versioning
4946 ---------------------------------------------------------------------------*/
4948 /* Adjust phi nodes for 'first' basic block. 'second' basic block is a copy
4949 of 'first'. Both of them are dominated by 'new_head' basic block. When
4950 'new_head' was created by 'second's incoming edge it received phi arguments
4951 on the edge by split_edge(). Later, additional edge 'e' was created to
4952 connect 'new_head' and 'first'. Now this routine adds phi args on this
4953 additional edge 'e' that new_head to second edge received as part of edge
4958 tree_lv_adjust_loop_header_phi (basic_block first, basic_block second,
4959 basic_block new_head, edge e)
4962 edge e2 = find_edge (new_head, second);
4964 /* Because NEW_HEAD has been created by splitting SECOND's incoming
4965 edge, we should always have an edge from NEW_HEAD to SECOND. */
4966 gcc_assert (e2 != NULL);
4968 /* Browse all 'second' basic block phi nodes and add phi args to
4969 edge 'e' for 'first' head. PHI args are always in correct order. */
4971 for (phi2 = phi_nodes (second), phi1 = phi_nodes (first);
4973 phi2 = PHI_CHAIN (phi2), phi1 = PHI_CHAIN (phi1))
4975 tree def = PHI_ARG_DEF (phi2, e2->dest_idx);
4976 add_phi_arg (phi1, def, e);
4980 /* Adds a if else statement to COND_BB with condition COND_EXPR.
4981 SECOND_HEAD is the destination of the THEN and FIRST_HEAD is
4982 the destination of the ELSE part. */
4984 tree_lv_add_condition_to_bb (basic_block first_head, basic_block second_head,
4985 basic_block cond_bb, void *cond_e)
4987 block_stmt_iterator bsi;
4988 tree goto1 = NULL_TREE;
4989 tree goto2 = NULL_TREE;
4990 tree new_cond_expr = NULL_TREE;
4991 tree cond_expr = (tree) cond_e;
4994 /* Build new conditional expr */
4995 goto1 = build1 (GOTO_EXPR, void_type_node, tree_block_label (first_head));
4996 goto2 = build1 (GOTO_EXPR, void_type_node, tree_block_label (second_head));
4997 new_cond_expr = build3 (COND_EXPR, void_type_node, cond_expr, goto1, goto2);
4999 /* Add new cond in cond_bb. */
5000 bsi = bsi_start (cond_bb);
5001 bsi_insert_after (&bsi, new_cond_expr, BSI_NEW_STMT);
5002 /* Adjust edges appropriately to connect new head with first head
5003 as well as second head. */
5004 e0 = single_succ_edge (cond_bb);
5005 e0->flags &= ~EDGE_FALLTHRU;
5006 e0->flags |= EDGE_FALSE_VALUE;
5009 struct cfg_hooks tree_cfg_hooks = {
5011 tree_verify_flow_info,
5012 tree_dump_bb, /* dump_bb */
5013 create_bb, /* create_basic_block */
5014 tree_redirect_edge_and_branch,/* redirect_edge_and_branch */
5015 tree_redirect_edge_and_branch_force,/* redirect_edge_and_branch_force */
5016 remove_bb, /* delete_basic_block */
5017 tree_split_block, /* split_block */
5018 tree_move_block_after, /* move_block_after */
5019 tree_can_merge_blocks_p, /* can_merge_blocks_p */
5020 tree_merge_blocks, /* merge_blocks */
5021 tree_predict_edge, /* predict_edge */
5022 tree_predicted_by_p, /* predicted_by_p */
5023 tree_can_duplicate_bb_p, /* can_duplicate_block_p */
5024 tree_duplicate_bb, /* duplicate_block */
5025 tree_split_edge, /* split_edge */
5026 tree_make_forwarder_block, /* make_forward_block */
5027 NULL, /* tidy_fallthru_edge */
5028 tree_block_ends_with_call_p, /* block_ends_with_call_p */
5029 tree_block_ends_with_condjump_p, /* block_ends_with_condjump_p */
5030 tree_flow_call_edges_add, /* flow_call_edges_add */
5031 tree_execute_on_growing_pred, /* execute_on_growing_pred */
5032 tree_execute_on_shrinking_pred, /* execute_on_shrinking_pred */
5033 tree_duplicate_loop_to_header_edge, /* duplicate loop for trees */
5034 tree_lv_add_condition_to_bb, /* lv_add_condition_to_bb */
5035 tree_lv_adjust_loop_header_phi, /* lv_adjust_loop_header_phi*/
5036 extract_true_false_edges_from_block, /* extract_cond_bb_edges */
5037 flush_pending_stmts /* flush_pending_stmts */
5041 /* Split all critical edges. */
5044 split_critical_edges (void)
5050 /* split_edge can redirect edges out of SWITCH_EXPRs, which can get
5051 expensive. So we want to enable recording of edge to CASE_LABEL_EXPR
5052 mappings around the calls to split_edge. */
5053 start_recording_case_labels ();
5056 FOR_EACH_EDGE (e, ei, bb->succs)
5057 if (EDGE_CRITICAL_P (e) && !(e->flags & EDGE_ABNORMAL))
5062 end_recording_case_labels ();
5065 struct tree_opt_pass pass_split_crit_edges =
5067 "crited", /* name */
5069 split_critical_edges, /* execute */
5072 0, /* static_pass_number */
5073 TV_TREE_SPLIT_EDGES, /* tv_id */
5074 PROP_cfg, /* properties required */
5075 PROP_no_crit_edges, /* properties_provided */
5076 0, /* properties_destroyed */
5077 0, /* todo_flags_start */
5078 TODO_dump_func, /* todo_flags_finish */
5083 /* Return EXP if it is a valid GIMPLE rvalue, else gimplify it into
5084 a temporary, make sure and register it to be renamed if necessary,
5085 and finally return the temporary. Put the statements to compute
5086 EXP before the current statement in BSI. */
5089 gimplify_val (block_stmt_iterator *bsi, tree type, tree exp)
5091 tree t, new_stmt, orig_stmt;
5093 if (is_gimple_val (exp))
5096 t = make_rename_temp (type, NULL);
5097 new_stmt = build2 (MODIFY_EXPR, type, t, exp);
5099 orig_stmt = bsi_stmt (*bsi);
5100 SET_EXPR_LOCUS (new_stmt, EXPR_LOCUS (orig_stmt));
5101 TREE_BLOCK (new_stmt) = TREE_BLOCK (orig_stmt);
5103 bsi_insert_before (bsi, new_stmt, BSI_SAME_STMT);
5108 /* Build a ternary operation and gimplify it. Emit code before BSI.
5109 Return the gimple_val holding the result. */
5112 gimplify_build3 (block_stmt_iterator *bsi, enum tree_code code,
5113 tree type, tree a, tree b, tree c)
5117 ret = fold_build3 (code, type, a, b, c);
5120 return gimplify_val (bsi, type, ret);
5123 /* Build a binary operation and gimplify it. Emit code before BSI.
5124 Return the gimple_val holding the result. */
5127 gimplify_build2 (block_stmt_iterator *bsi, enum tree_code code,
5128 tree type, tree a, tree b)
5132 ret = fold_build2 (code, type, a, b);
5135 return gimplify_val (bsi, type, ret);
5138 /* Build a unary operation and gimplify it. Emit code before BSI.
5139 Return the gimple_val holding the result. */
5142 gimplify_build1 (block_stmt_iterator *bsi, enum tree_code code, tree type,
5147 ret = fold_build1 (code, type, a);
5150 return gimplify_val (bsi, type, ret);
5155 /* Emit return warnings. */
5158 execute_warn_function_return (void)
5160 #ifdef USE_MAPPED_LOCATION
5161 source_location location;
5169 /* If we have a path to EXIT, then we do return. */
5170 if (TREE_THIS_VOLATILE (cfun->decl)
5171 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) > 0)
5173 #ifdef USE_MAPPED_LOCATION
5174 location = UNKNOWN_LOCATION;
5178 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
5180 last = last_stmt (e->src);
5181 if (TREE_CODE (last) == RETURN_EXPR
5182 #ifdef USE_MAPPED_LOCATION
5183 && (location = EXPR_LOCATION (last)) != UNKNOWN_LOCATION)
5185 && (locus = EXPR_LOCUS (last)) != NULL)
5189 #ifdef USE_MAPPED_LOCATION
5190 if (location == UNKNOWN_LOCATION)
5191 location = cfun->function_end_locus;
5192 warning (0, "%H%<noreturn%> function does return", &location);
5195 locus = &cfun->function_end_locus;
5196 warning (0, "%H%<noreturn%> function does return", locus);
5200 /* If we see "return;" in some basic block, then we do reach the end
5201 without returning a value. */
5202 else if (warn_return_type
5203 && !TREE_NO_WARNING (cfun->decl)
5204 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) > 0
5205 && !VOID_TYPE_P (TREE_TYPE (TREE_TYPE (cfun->decl))))
5207 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
5209 tree last = last_stmt (e->src);
5210 if (TREE_CODE (last) == RETURN_EXPR
5211 && TREE_OPERAND (last, 0) == NULL
5212 && !TREE_NO_WARNING (last))
5214 #ifdef USE_MAPPED_LOCATION
5215 location = EXPR_LOCATION (last);
5216 if (location == UNKNOWN_LOCATION)
5217 location = cfun->function_end_locus;
5218 warning (0, "%Hcontrol reaches end of non-void function", &location);
5220 locus = EXPR_LOCUS (last);
5222 locus = &cfun->function_end_locus;
5223 warning (0, "%Hcontrol reaches end of non-void function", locus);
5225 TREE_NO_WARNING (cfun->decl) = 1;
5233 /* Given a basic block B which ends with a conditional and has
5234 precisely two successors, determine which of the edges is taken if
5235 the conditional is true and which is taken if the conditional is
5236 false. Set TRUE_EDGE and FALSE_EDGE appropriately. */
5239 extract_true_false_edges_from_block (basic_block b,
5243 edge e = EDGE_SUCC (b, 0);
5245 if (e->flags & EDGE_TRUE_VALUE)
5248 *false_edge = EDGE_SUCC (b, 1);
5253 *true_edge = EDGE_SUCC (b, 1);
5257 struct tree_opt_pass pass_warn_function_return =
5261 execute_warn_function_return, /* execute */
5264 0, /* static_pass_number */
5266 PROP_cfg, /* properties_required */
5267 0, /* properties_provided */
5268 0, /* properties_destroyed */
5269 0, /* todo_flags_start */
5270 0, /* todo_flags_finish */
5274 /* Emit noreturn warnings. */
5277 execute_warn_function_noreturn (void)
5279 if (warn_missing_noreturn
5280 && !TREE_THIS_VOLATILE (cfun->decl)
5281 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) == 0
5282 && !lang_hooks.function.missing_noreturn_ok_p (cfun->decl))
5283 warning (OPT_Wmissing_noreturn, "%Jfunction might be possible candidate "
5284 "for attribute %<noreturn%>",
5288 struct tree_opt_pass pass_warn_function_noreturn =
5292 execute_warn_function_noreturn, /* execute */
5295 0, /* static_pass_number */
5297 PROP_cfg, /* properties_required */
5298 0, /* properties_provided */
5299 0, /* properties_destroyed */
5300 0, /* todo_flags_start */
5301 0, /* todo_flags_finish */