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, 59 Temple Place - Suite 330,
20 Boston, MA 02111-1307, USA. */
24 #include "coretypes.h"
29 #include "hard-reg-set.h"
30 #include "basic-block.h"
37 #include "langhooks.h"
38 #include "diagnostic.h"
39 #include "tree-flow.h"
41 #include "tree-dump.h"
42 #include "tree-pass.h"
46 #include "cfglayout.h"
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 create_block_annotation (basic_block);
98 static void free_blocks_annotations (void);
99 static void clear_blocks_annotations (void);
100 static void make_blocks (tree);
101 static void factor_computed_gotos (void);
104 static void make_edges (void);
105 static void make_ctrl_stmt_edges (basic_block);
106 static void make_exit_edges (basic_block);
107 static void make_cond_expr_edges (basic_block);
108 static void make_switch_expr_edges (basic_block);
109 static void make_goto_expr_edges (basic_block);
110 static edge tree_redirect_edge_and_branch (edge, basic_block);
111 static edge tree_try_redirect_by_replacing_jump (edge, basic_block);
112 static void split_critical_edges (void);
113 static bool remove_fallthru_edge (VEC(edge,gc) *);
115 /* Various helpers. */
116 static inline bool stmt_starts_bb_p (tree, tree);
117 static int tree_verify_flow_info (void);
118 static void tree_make_forwarder_block (edge);
119 static bool tree_forwarder_block_p (basic_block, bool);
120 static void tree_cfg2vcg (FILE *);
122 /* Flowgraph optimization and cleanup. */
123 static void tree_merge_blocks (basic_block, basic_block);
124 static bool tree_can_merge_blocks_p (basic_block, basic_block);
125 static void remove_bb (basic_block);
126 static bool cleanup_control_flow (void);
127 static bool cleanup_control_expr_graph (basic_block, block_stmt_iterator);
128 static edge find_taken_edge_computed_goto (basic_block, tree);
129 static edge find_taken_edge_cond_expr (basic_block, tree);
130 static edge find_taken_edge_switch_expr (basic_block, tree);
131 static tree find_case_label_for_value (tree, tree);
132 static bool phi_alternatives_equal (basic_block, edge, edge);
133 static bool cleanup_forwarder_blocks (void);
136 /*---------------------------------------------------------------------------
138 ---------------------------------------------------------------------------*/
140 /* Entry point to the CFG builder for trees. TP points to the list of
141 statements to be added to the flowgraph. */
144 build_tree_cfg (tree *tp)
146 /* Register specific tree functions. */
147 tree_register_cfg_hooks ();
149 /* Initialize the basic block array. */
151 profile_status = PROFILE_ABSENT;
153 last_basic_block = 0;
154 VARRAY_BB_INIT (basic_block_info, initial_cfg_capacity, "basic_block_info");
155 memset ((void *) &cfg_stats, 0, sizeof (cfg_stats));
157 /* Build a mapping of labels to their associated blocks. */
158 VARRAY_BB_INIT (label_to_block_map, initial_cfg_capacity,
159 "label to block map");
161 ENTRY_BLOCK_PTR->next_bb = EXIT_BLOCK_PTR;
162 EXIT_BLOCK_PTR->prev_bb = ENTRY_BLOCK_PTR;
164 found_computed_goto = 0;
167 /* Computed gotos are hell to deal with, especially if there are
168 lots of them with a large number of destinations. So we factor
169 them to a common computed goto location before we build the
170 edge list. After we convert back to normal form, we will un-factor
171 the computed gotos since factoring introduces an unwanted jump. */
172 if (found_computed_goto)
173 factor_computed_gotos ();
175 /* Make sure there is always at least one block, even if it's empty. */
176 if (n_basic_blocks == 0)
177 create_empty_bb (ENTRY_BLOCK_PTR);
179 create_block_annotation (ENTRY_BLOCK_PTR);
180 create_block_annotation (EXIT_BLOCK_PTR);
182 /* Adjust the size of the array. */
183 VARRAY_GROW (basic_block_info, n_basic_blocks);
185 /* To speed up statement iterator walks, we first purge dead labels. */
186 cleanup_dead_labels ();
188 /* Group case nodes to reduce the number of edges.
189 We do this after cleaning up dead labels because otherwise we miss
190 a lot of obvious case merging opportunities. */
191 group_case_labels ();
193 /* Create the edges of the flowgraph. */
196 /* Debugging dumps. */
198 /* Write the flowgraph to a VCG file. */
200 int local_dump_flags;
201 FILE *dump_file = dump_begin (TDI_vcg, &local_dump_flags);
204 tree_cfg2vcg (dump_file);
205 dump_end (TDI_vcg, dump_file);
209 /* Dump a textual representation of the flowgraph. */
211 dump_tree_cfg (dump_file, dump_flags);
215 execute_build_cfg (void)
217 build_tree_cfg (&DECL_SAVED_TREE (current_function_decl));
220 struct tree_opt_pass pass_build_cfg =
224 execute_build_cfg, /* execute */
227 0, /* static_pass_number */
228 TV_TREE_CFG, /* tv_id */
229 PROP_gimple_leh, /* properties_required */
230 PROP_cfg, /* properties_provided */
231 0, /* properties_destroyed */
232 0, /* todo_flags_start */
233 TODO_verify_stmts, /* todo_flags_finish */
237 /* Search the CFG for any computed gotos. If found, factor them to a
238 common computed goto site. Also record the location of that site so
239 that we can un-factor the gotos after we have converted back to
243 factor_computed_gotos (void)
246 tree factored_label_decl = NULL;
248 tree factored_computed_goto_label = NULL;
249 tree factored_computed_goto = NULL;
251 /* We know there are one or more computed gotos in this function.
252 Examine the last statement in each basic block to see if the block
253 ends with a computed goto. */
257 block_stmt_iterator bsi = bsi_last (bb);
262 last = bsi_stmt (bsi);
264 /* Ignore the computed goto we create when we factor the original
266 if (last == factored_computed_goto)
269 /* If the last statement is a computed goto, factor it. */
270 if (computed_goto_p (last))
274 /* The first time we find a computed goto we need to create
275 the factored goto block and the variable each original
276 computed goto will use for their goto destination. */
277 if (! factored_computed_goto)
279 basic_block new_bb = create_empty_bb (bb);
280 block_stmt_iterator new_bsi = bsi_start (new_bb);
282 /* Create the destination of the factored goto. Each original
283 computed goto will put its desired destination into this
284 variable and jump to the label we create immediately
286 var = create_tmp_var (ptr_type_node, "gotovar");
288 /* Build a label for the new block which will contain the
289 factored computed goto. */
290 factored_label_decl = create_artificial_label ();
291 factored_computed_goto_label
292 = build1 (LABEL_EXPR, void_type_node, factored_label_decl);
293 bsi_insert_after (&new_bsi, factored_computed_goto_label,
296 /* Build our new computed goto. */
297 factored_computed_goto = build1 (GOTO_EXPR, void_type_node, var);
298 bsi_insert_after (&new_bsi, factored_computed_goto,
302 /* Copy the original computed goto's destination into VAR. */
303 assignment = build (MODIFY_EXPR, ptr_type_node,
304 var, GOTO_DESTINATION (last));
305 bsi_insert_before (&bsi, assignment, BSI_SAME_STMT);
307 /* And re-vector the computed goto to the new destination. */
308 GOTO_DESTINATION (last) = factored_label_decl;
314 /* Create annotations for a single basic block. */
317 create_block_annotation (basic_block bb)
319 /* Verify that the tree_annotations field is clear. */
320 gcc_assert (!bb->tree_annotations);
321 bb->tree_annotations = ggc_alloc_cleared (sizeof (struct bb_ann_d));
325 /* Free the annotations for all the basic blocks. */
327 static void free_blocks_annotations (void)
329 clear_blocks_annotations ();
333 /* Clear the annotations for all the basic blocks. */
336 clear_blocks_annotations (void)
340 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb)
341 bb->tree_annotations = NULL;
345 /* Build a flowgraph for the statement_list STMT_LIST. */
348 make_blocks (tree stmt_list)
350 tree_stmt_iterator i = tsi_start (stmt_list);
352 bool start_new_block = true;
353 bool first_stmt_of_list = true;
354 basic_block bb = ENTRY_BLOCK_PTR;
356 while (!tsi_end_p (i))
363 /* If the statement starts a new basic block or if we have determined
364 in a previous pass that we need to create a new block for STMT, do
366 if (start_new_block || stmt_starts_bb_p (stmt, prev_stmt))
368 if (!first_stmt_of_list)
369 stmt_list = tsi_split_statement_list_before (&i);
370 bb = create_basic_block (stmt_list, NULL, bb);
371 start_new_block = false;
374 /* Now add STMT to BB and create the subgraphs for special statement
376 set_bb_for_stmt (stmt, bb);
378 if (computed_goto_p (stmt))
379 found_computed_goto = true;
381 /* If STMT is a basic block terminator, set START_NEW_BLOCK for the
383 if (stmt_ends_bb_p (stmt))
384 start_new_block = true;
387 first_stmt_of_list = false;
392 /* Create and return a new empty basic block after bb AFTER. */
395 create_bb (void *h, void *e, basic_block after)
401 /* Create and initialize a new basic block. Since alloc_block uses
402 ggc_alloc_cleared to allocate a basic block, we do not have to
403 clear the newly allocated basic block here. */
406 bb->index = last_basic_block;
408 bb->stmt_list = h ? h : alloc_stmt_list ();
410 /* Add the new block to the linked list of blocks. */
411 link_block (bb, after);
413 /* Grow the basic block array if needed. */
414 if ((size_t) last_basic_block == VARRAY_SIZE (basic_block_info))
416 size_t new_size = last_basic_block + (last_basic_block + 3) / 4;
417 VARRAY_GROW (basic_block_info, new_size);
420 /* Add the newly created block to the array. */
421 BASIC_BLOCK (last_basic_block) = bb;
423 create_block_annotation (bb);
428 initialize_bb_rbi (bb);
433 /*---------------------------------------------------------------------------
435 ---------------------------------------------------------------------------*/
437 /* Fold COND_EXPR_COND of each COND_EXPR. */
440 fold_cond_expr_cond (void)
446 tree stmt = last_stmt (bb);
449 && TREE_CODE (stmt) == COND_EXPR)
451 tree cond = fold (COND_EXPR_COND (stmt));
452 if (integer_zerop (cond))
453 COND_EXPR_COND (stmt) = boolean_false_node;
454 else if (integer_onep (cond))
455 COND_EXPR_COND (stmt) = boolean_true_node;
460 /* Join all the blocks in the flowgraph. */
467 /* Create an edge from entry to the first block with executable
469 make_edge (ENTRY_BLOCK_PTR, BASIC_BLOCK (0), EDGE_FALLTHRU);
471 /* Traverse the basic block array placing edges. */
474 tree first = first_stmt (bb);
475 tree last = last_stmt (bb);
479 /* Edges for statements that always alter flow control. */
480 if (is_ctrl_stmt (last))
481 make_ctrl_stmt_edges (bb);
483 /* Edges for statements that sometimes alter flow control. */
484 if (is_ctrl_altering_stmt (last))
485 make_exit_edges (bb);
488 /* Finally, if no edges were created above, this is a regular
489 basic block that only needs a fallthru edge. */
490 if (EDGE_COUNT (bb->succs) == 0)
491 make_edge (bb, bb->next_bb, EDGE_FALLTHRU);
494 /* We do not care about fake edges, so remove any that the CFG
495 builder inserted for completeness. */
496 remove_fake_exit_edges ();
498 /* Fold COND_EXPR_COND of each COND_EXPR. */
499 fold_cond_expr_cond ();
501 /* Clean up the graph and warn for unreachable code. */
506 /* Create edges for control statement at basic block BB. */
509 make_ctrl_stmt_edges (basic_block bb)
511 tree last = last_stmt (bb);
514 switch (TREE_CODE (last))
517 make_goto_expr_edges (bb);
521 make_edge (bb, EXIT_BLOCK_PTR, 0);
525 make_cond_expr_edges (bb);
529 make_switch_expr_edges (bb);
533 make_eh_edges (last);
534 /* Yet another NORETURN hack. */
535 if (EDGE_COUNT (bb->succs) == 0)
536 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
545 /* Create exit edges for statements in block BB that alter the flow of
546 control. Statements that alter the control flow are 'goto', 'return'
547 and calls to non-returning functions. */
550 make_exit_edges (basic_block bb)
552 tree last = last_stmt (bb), op;
555 switch (TREE_CODE (last))
560 /* If this function receives a nonlocal goto, then we need to
561 make edges from this call site to all the nonlocal goto
563 if (TREE_SIDE_EFFECTS (last)
564 && current_function_has_nonlocal_label)
565 make_goto_expr_edges (bb);
567 /* If this statement has reachable exception handlers, then
568 create abnormal edges to them. */
569 make_eh_edges (last);
571 /* Some calls are known not to return. For such calls we create
574 We really need to revamp how we build edges so that it's not
575 such a bloody pain to avoid creating edges for this case since
576 all we do is remove these edges when we're done building the
578 if (call_expr_flags (last) & ECF_NORETURN)
580 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
584 /* Don't forget the fall-thru edge. */
585 make_edge (bb, bb->next_bb, EDGE_FALLTHRU);
589 /* A MODIFY_EXPR may have a CALL_EXPR on its RHS and the CALL_EXPR
590 may have an abnormal edge. Search the RHS for this case and
591 create any required edges. */
592 op = get_call_expr_in (last);
593 if (op && TREE_SIDE_EFFECTS (op)
594 && current_function_has_nonlocal_label)
595 make_goto_expr_edges (bb);
597 make_eh_edges (last);
598 make_edge (bb, bb->next_bb, EDGE_FALLTHRU);
607 /* Create the edges for a COND_EXPR starting at block BB.
608 At this point, both clauses must contain only simple gotos. */
611 make_cond_expr_edges (basic_block bb)
613 tree entry = last_stmt (bb);
614 basic_block then_bb, else_bb;
615 tree then_label, else_label;
618 gcc_assert (TREE_CODE (entry) == COND_EXPR);
620 /* Entry basic blocks for each component. */
621 then_label = GOTO_DESTINATION (COND_EXPR_THEN (entry));
622 else_label = GOTO_DESTINATION (COND_EXPR_ELSE (entry));
623 then_bb = label_to_block (then_label);
624 else_bb = label_to_block (else_label);
626 make_edge (bb, then_bb, EDGE_TRUE_VALUE);
627 make_edge (bb, else_bb, EDGE_FALSE_VALUE);
630 /* Hashing routine for EDGE_TO_CASES. */
633 edge_to_cases_hash (const void *p)
635 edge e = ((struct edge_to_cases_elt *)p)->e;
637 /* Hash on the edge itself (which is a pointer). */
638 return htab_hash_pointer (e);
641 /* Equality routine for EDGE_TO_CASES, edges are unique, so testing
642 for equality is just a pointer comparison. */
645 edge_to_cases_eq (const void *p1, const void *p2)
647 edge e1 = ((struct edge_to_cases_elt *)p1)->e;
648 edge e2 = ((struct edge_to_cases_elt *)p2)->e;
653 /* Called for each element in the hash table (P) as we delete the
654 edge to cases hash table.
656 Clear all the TREE_CHAINs to prevent problems with copying of
657 SWITCH_EXPRs and structure sharing rules, then free the hash table
661 edge_to_cases_cleanup (void *p)
663 struct edge_to_cases_elt *elt = p;
666 for (t = elt->case_labels; t; t = next)
668 next = TREE_CHAIN (t);
669 TREE_CHAIN (t) = NULL;
674 /* Start recording information mapping edges to case labels. */
677 start_recording_case_labels (void)
679 gcc_assert (edge_to_cases == NULL);
681 edge_to_cases = htab_create (37,
684 edge_to_cases_cleanup);
687 /* Return nonzero if we are recording information for case labels. */
690 recording_case_labels_p (void)
692 return (edge_to_cases != NULL);
695 /* Stop recording information mapping edges to case labels and
696 remove any information we have recorded. */
698 end_recording_case_labels (void)
700 htab_delete (edge_to_cases);
701 edge_to_cases = NULL;
704 /* Record that CASE_LABEL (a CASE_LABEL_EXPR) references edge E. */
707 record_switch_edge (edge e, tree case_label)
709 struct edge_to_cases_elt *elt;
712 /* Build a hash table element so we can see if E is already
714 elt = xmalloc (sizeof (struct edge_to_cases_elt));
716 elt->case_labels = case_label;
718 slot = htab_find_slot (edge_to_cases, elt, INSERT);
722 /* E was not in the hash table. Install E into the hash table. */
727 /* E was already in the hash table. Free ELT as we do not need it
731 /* Get the entry stored in the hash table. */
732 elt = (struct edge_to_cases_elt *) *slot;
734 /* Add it to the chain of CASE_LABEL_EXPRs referencing E. */
735 TREE_CHAIN (case_label) = elt->case_labels;
736 elt->case_labels = case_label;
740 /* If we are inside a {start,end}_recording_cases block, then return
741 a chain of CASE_LABEL_EXPRs from T which reference E.
743 Otherwise return NULL. */
746 get_cases_for_edge (edge e, tree t)
748 struct edge_to_cases_elt elt, *elt_p;
753 /* If we are not recording cases, then we do not have CASE_LABEL_EXPR
754 chains available. Return NULL so the caller can detect this case. */
755 if (!recording_case_labels_p ())
760 elt.case_labels = NULL;
761 slot = htab_find_slot (edge_to_cases, &elt, NO_INSERT);
765 elt_p = (struct edge_to_cases_elt *)*slot;
766 return elt_p->case_labels;
769 /* If we did not find E in the hash table, then this must be the first
770 time we have been queried for information about E & T. Add all the
771 elements from T to the hash table then perform the query again. */
773 vec = SWITCH_LABELS (t);
774 n = TREE_VEC_LENGTH (vec);
775 for (i = 0; i < n; i++)
777 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
778 basic_block label_bb = label_to_block (lab);
779 record_switch_edge (find_edge (e->src, label_bb), TREE_VEC_ELT (vec, i));
784 /* Create the edges for a SWITCH_EXPR starting at block BB.
785 At this point, the switch body has been lowered and the
786 SWITCH_LABELS filled in, so this is in effect a multi-way branch. */
789 make_switch_expr_edges (basic_block bb)
791 tree entry = last_stmt (bb);
795 vec = SWITCH_LABELS (entry);
796 n = TREE_VEC_LENGTH (vec);
798 for (i = 0; i < n; ++i)
800 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
801 basic_block label_bb = label_to_block (lab);
802 make_edge (bb, label_bb, 0);
807 /* Return the basic block holding label DEST. */
810 label_to_block_fn (struct function *ifun, tree dest)
812 int uid = LABEL_DECL_UID (dest);
814 /* We would die hard when faced by an undefined label. Emit a label to
815 the very first basic block. This will hopefully make even the dataflow
816 and undefined variable warnings quite right. */
817 if ((errorcount || sorrycount) && uid < 0)
819 block_stmt_iterator bsi = bsi_start (BASIC_BLOCK (0));
822 stmt = build1 (LABEL_EXPR, void_type_node, dest);
823 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
824 uid = LABEL_DECL_UID (dest);
826 if (VARRAY_SIZE (ifun->cfg->x_label_to_block_map) <= (unsigned int)uid)
828 return VARRAY_BB (ifun->cfg->x_label_to_block_map, uid);
831 /* Create edges for a goto statement at block BB. */
834 make_goto_expr_edges (basic_block bb)
837 basic_block target_bb;
839 block_stmt_iterator last = bsi_last (bb);
841 goto_t = bsi_stmt (last);
843 /* If the last statement is not a GOTO (i.e., it is a RETURN_EXPR,
844 CALL_EXPR or MODIFY_EXPR), then the edge is an abnormal edge resulting
845 from a nonlocal goto. */
846 if (TREE_CODE (goto_t) != GOTO_EXPR)
850 tree dest = GOTO_DESTINATION (goto_t);
853 /* A GOTO to a local label creates normal edges. */
854 if (simple_goto_p (goto_t))
856 edge e = make_edge (bb, label_to_block (dest), EDGE_FALLTHRU);
857 #ifdef USE_MAPPED_LOCATION
858 e->goto_locus = EXPR_LOCATION (goto_t);
860 e->goto_locus = EXPR_LOCUS (goto_t);
866 /* Nothing more to do for nonlocal gotos. */
867 if (TREE_CODE (dest) == LABEL_DECL)
870 /* Computed gotos remain. */
873 /* Look for the block starting with the destination label. In the
874 case of a computed goto, make an edge to any label block we find
876 FOR_EACH_BB (target_bb)
878 block_stmt_iterator bsi;
880 for (bsi = bsi_start (target_bb); !bsi_end_p (bsi); bsi_next (&bsi))
882 tree target = bsi_stmt (bsi);
884 if (TREE_CODE (target) != LABEL_EXPR)
888 /* Computed GOTOs. Make an edge to every label block that has
889 been marked as a potential target for a computed goto. */
890 (FORCED_LABEL (LABEL_EXPR_LABEL (target)) && for_call == 0)
891 /* Nonlocal GOTO target. Make an edge to every label block
892 that has been marked as a potential target for a nonlocal
894 || (DECL_NONLOCAL (LABEL_EXPR_LABEL (target)) && for_call == 1))
896 make_edge (bb, target_bb, EDGE_ABNORMAL);
902 /* Degenerate case of computed goto with no labels. */
903 if (!for_call && EDGE_COUNT (bb->succs) == 0)
904 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
908 /*---------------------------------------------------------------------------
910 ---------------------------------------------------------------------------*/
912 /* Remove unreachable blocks and other miscellaneous clean up work. */
915 cleanup_tree_cfg (void)
919 timevar_push (TV_TREE_CLEANUP_CFG);
921 retval = cleanup_control_flow ();
922 retval |= delete_unreachable_blocks ();
924 /* cleanup_forwarder_blocks can redirect edges out of SWITCH_EXPRs,
925 which can get expensive. So we want to enable recording of edge
926 to CASE_LABEL_EXPR mappings around the call to
927 cleanup_forwarder_blocks. */
928 start_recording_case_labels ();
929 retval |= cleanup_forwarder_blocks ();
930 end_recording_case_labels ();
932 #ifdef ENABLE_CHECKING
935 gcc_assert (!cleanup_control_flow ());
936 gcc_assert (!delete_unreachable_blocks ());
937 gcc_assert (!cleanup_forwarder_blocks ());
941 /* Merging the blocks creates no new opportunities for the other
942 optimizations, so do it here. */
943 retval |= merge_seq_blocks ();
947 #ifdef ENABLE_CHECKING
950 timevar_pop (TV_TREE_CLEANUP_CFG);
955 /* Cleanup cfg and repair loop structures. */
958 cleanup_tree_cfg_loop (void)
960 bitmap changed_bbs = BITMAP_ALLOC (NULL);
964 fix_loop_structure (current_loops, changed_bbs);
965 calculate_dominance_info (CDI_DOMINATORS);
967 /* This usually does nothing. But sometimes parts of cfg that originally
968 were inside a loop get out of it due to edge removal (since they
969 become unreachable by back edges from latch). */
970 rewrite_into_loop_closed_ssa (changed_bbs, TODO_update_ssa);
972 BITMAP_FREE (changed_bbs);
974 #ifdef ENABLE_CHECKING
975 verify_loop_structure (current_loops);
979 /* Cleanup useless labels in basic blocks. This is something we wish
980 to do early because it allows us to group case labels before creating
981 the edges for the CFG, and it speeds up block statement iterators in
983 We only run this pass once, running it more than once is probably not
986 /* A map from basic block index to the leading label of that block. */
987 static tree *label_for_bb;
989 /* Callback for for_each_eh_region. Helper for cleanup_dead_labels. */
991 update_eh_label (struct eh_region *region)
993 tree old_label = get_eh_region_tree_label (region);
997 basic_block bb = label_to_block (old_label);
999 /* ??? After optimizing, there may be EH regions with labels
1000 that have already been removed from the function body, so
1001 there is no basic block for them. */
1005 new_label = label_for_bb[bb->index];
1006 set_eh_region_tree_label (region, new_label);
1010 /* Given LABEL return the first label in the same basic block. */
1012 main_block_label (tree label)
1014 basic_block bb = label_to_block (label);
1016 /* label_to_block possibly inserted undefined label into the chain. */
1017 if (!label_for_bb[bb->index])
1018 label_for_bb[bb->index] = label;
1019 return label_for_bb[bb->index];
1022 /* Cleanup redundant labels. This is a three-step process:
1023 1) Find the leading label for each block.
1024 2) Redirect all references to labels to the leading labels.
1025 3) Cleanup all useless labels. */
1028 cleanup_dead_labels (void)
1031 label_for_bb = xcalloc (last_basic_block, sizeof (tree));
1033 /* Find a suitable label for each block. We use the first user-defined
1034 label if there is one, or otherwise just the first label we see. */
1037 block_stmt_iterator i;
1039 for (i = bsi_start (bb); !bsi_end_p (i); bsi_next (&i))
1041 tree label, stmt = bsi_stmt (i);
1043 if (TREE_CODE (stmt) != LABEL_EXPR)
1046 label = LABEL_EXPR_LABEL (stmt);
1048 /* If we have not yet seen a label for the current block,
1049 remember this one and see if there are more labels. */
1050 if (! label_for_bb[bb->index])
1052 label_for_bb[bb->index] = label;
1056 /* If we did see a label for the current block already, but it
1057 is an artificially created label, replace it if the current
1058 label is a user defined label. */
1059 if (! DECL_ARTIFICIAL (label)
1060 && DECL_ARTIFICIAL (label_for_bb[bb->index]))
1062 label_for_bb[bb->index] = label;
1068 /* Now redirect all jumps/branches to the selected label.
1069 First do so for each block ending in a control statement. */
1072 tree stmt = last_stmt (bb);
1076 switch (TREE_CODE (stmt))
1080 tree true_branch, false_branch;
1082 true_branch = COND_EXPR_THEN (stmt);
1083 false_branch = COND_EXPR_ELSE (stmt);
1085 GOTO_DESTINATION (true_branch)
1086 = main_block_label (GOTO_DESTINATION (true_branch));
1087 GOTO_DESTINATION (false_branch)
1088 = main_block_label (GOTO_DESTINATION (false_branch));
1096 tree vec = SWITCH_LABELS (stmt);
1097 size_t n = TREE_VEC_LENGTH (vec);
1099 /* Replace all destination labels. */
1100 for (i = 0; i < n; ++i)
1102 tree elt = TREE_VEC_ELT (vec, i);
1103 tree label = main_block_label (CASE_LABEL (elt));
1104 CASE_LABEL (elt) = label;
1109 /* We have to handle GOTO_EXPRs until they're removed, and we don't
1110 remove them until after we've created the CFG edges. */
1112 if (! computed_goto_p (stmt))
1114 GOTO_DESTINATION (stmt)
1115 = main_block_label (GOTO_DESTINATION (stmt));
1124 for_each_eh_region (update_eh_label);
1126 /* Finally, purge dead labels. All user-defined labels and labels that
1127 can be the target of non-local gotos are preserved. */
1130 block_stmt_iterator i;
1131 tree label_for_this_bb = label_for_bb[bb->index];
1133 if (! label_for_this_bb)
1136 for (i = bsi_start (bb); !bsi_end_p (i); )
1138 tree label, stmt = bsi_stmt (i);
1140 if (TREE_CODE (stmt) != LABEL_EXPR)
1143 label = LABEL_EXPR_LABEL (stmt);
1145 if (label == label_for_this_bb
1146 || ! DECL_ARTIFICIAL (label)
1147 || DECL_NONLOCAL (label))
1154 free (label_for_bb);
1157 /* Look for blocks ending in a multiway branch (a SWITCH_EXPR in GIMPLE),
1158 and scan the sorted vector of cases. Combine the ones jumping to the
1160 Eg. three separate entries 1: 2: 3: become one entry 1..3: */
1163 group_case_labels (void)
1169 tree stmt = last_stmt (bb);
1170 if (stmt && TREE_CODE (stmt) == SWITCH_EXPR)
1172 tree labels = SWITCH_LABELS (stmt);
1173 int old_size = TREE_VEC_LENGTH (labels);
1174 int i, j, new_size = old_size;
1175 tree default_case = TREE_VEC_ELT (labels, old_size - 1);
1178 /* The default label is always the last case in a switch
1179 statement after gimplification. */
1180 default_label = CASE_LABEL (default_case);
1182 /* Look for possible opportunities to merge cases.
1183 Ignore the last element of the label vector because it
1184 must be the default case. */
1186 while (i < old_size - 1)
1188 tree base_case, base_label, base_high;
1189 base_case = TREE_VEC_ELT (labels, i);
1191 gcc_assert (base_case);
1192 base_label = CASE_LABEL (base_case);
1194 /* Discard cases that have the same destination as the
1196 if (base_label == default_label)
1198 TREE_VEC_ELT (labels, i) = NULL_TREE;
1204 base_high = CASE_HIGH (base_case) ?
1205 CASE_HIGH (base_case) : CASE_LOW (base_case);
1207 /* Try to merge case labels. Break out when we reach the end
1208 of the label vector or when we cannot merge the next case
1209 label with the current one. */
1210 while (i < old_size - 1)
1212 tree merge_case = TREE_VEC_ELT (labels, i);
1213 tree merge_label = CASE_LABEL (merge_case);
1214 tree t = int_const_binop (PLUS_EXPR, base_high,
1215 integer_one_node, 1);
1217 /* Merge the cases if they jump to the same place,
1218 and their ranges are consecutive. */
1219 if (merge_label == base_label
1220 && tree_int_cst_equal (CASE_LOW (merge_case), t))
1222 base_high = CASE_HIGH (merge_case) ?
1223 CASE_HIGH (merge_case) : CASE_LOW (merge_case);
1224 CASE_HIGH (base_case) = base_high;
1225 TREE_VEC_ELT (labels, i) = NULL_TREE;
1234 /* Compress the case labels in the label vector, and adjust the
1235 length of the vector. */
1236 for (i = 0, j = 0; i < new_size; i++)
1238 while (! TREE_VEC_ELT (labels, j))
1240 TREE_VEC_ELT (labels, i) = TREE_VEC_ELT (labels, j++);
1242 TREE_VEC_LENGTH (labels) = new_size;
1247 /* Checks whether we can merge block B into block A. */
1250 tree_can_merge_blocks_p (basic_block a, basic_block b)
1253 block_stmt_iterator bsi;
1255 if (!single_succ_p (a))
1258 if (single_succ_edge (a)->flags & EDGE_ABNORMAL)
1261 if (single_succ (a) != b)
1264 if (!single_pred_p (b))
1267 if (b == EXIT_BLOCK_PTR)
1270 /* If A ends by a statement causing exceptions or something similar, we
1271 cannot merge the blocks. */
1272 stmt = last_stmt (a);
1273 if (stmt && stmt_ends_bb_p (stmt))
1276 /* Do not allow a block with only a non-local label to be merged. */
1277 if (stmt && TREE_CODE (stmt) == LABEL_EXPR
1278 && DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)))
1281 /* There may be no PHI nodes at the start of B. */
1285 /* Do not remove user labels. */
1286 for (bsi = bsi_start (b); !bsi_end_p (bsi); bsi_next (&bsi))
1288 stmt = bsi_stmt (bsi);
1289 if (TREE_CODE (stmt) != LABEL_EXPR)
1291 if (!DECL_ARTIFICIAL (LABEL_EXPR_LABEL (stmt)))
1295 /* Protect the loop latches. */
1297 && b->loop_father->latch == b)
1304 /* Merge block B into block A. */
1307 tree_merge_blocks (basic_block a, basic_block b)
1309 block_stmt_iterator bsi;
1310 tree_stmt_iterator last;
1313 fprintf (dump_file, "Merging blocks %d and %d\n", a->index, b->index);
1315 /* Ensure that B follows A. */
1316 move_block_after (b, a);
1318 gcc_assert (single_succ_edge (a)->flags & EDGE_FALLTHRU);
1319 gcc_assert (!last_stmt (a) || !stmt_ends_bb_p (last_stmt (a)));
1321 /* Remove labels from B and set bb_for_stmt to A for other statements. */
1322 for (bsi = bsi_start (b); !bsi_end_p (bsi);)
1324 if (TREE_CODE (bsi_stmt (bsi)) == LABEL_EXPR)
1326 tree label = bsi_stmt (bsi);
1329 /* Now that we can thread computed gotos, we might have
1330 a situation where we have a forced label in block B
1331 However, the label at the start of block B might still be
1332 used in other ways (think about the runtime checking for
1333 Fortran assigned gotos). So we can not just delete the
1334 label. Instead we move the label to the start of block A. */
1335 if (FORCED_LABEL (LABEL_EXPR_LABEL (label)))
1337 block_stmt_iterator dest_bsi = bsi_start (a);
1338 bsi_insert_before (&dest_bsi, label, BSI_NEW_STMT);
1343 set_bb_for_stmt (bsi_stmt (bsi), a);
1348 /* Merge the chains. */
1349 last = tsi_last (a->stmt_list);
1350 tsi_link_after (&last, b->stmt_list, TSI_NEW_STMT);
1351 b->stmt_list = NULL;
1355 /* Walk the function tree removing unnecessary statements.
1357 * Empty statement nodes are removed
1359 * Unnecessary TRY_FINALLY and TRY_CATCH blocks are removed
1361 * Unnecessary COND_EXPRs are removed
1363 * Some unnecessary BIND_EXPRs are removed
1365 Clearly more work could be done. The trick is doing the analysis
1366 and removal fast enough to be a net improvement in compile times.
1368 Note that when we remove a control structure such as a COND_EXPR
1369 BIND_EXPR, or TRY block, we will need to repeat this optimization pass
1370 to ensure we eliminate all the useless code. */
1381 static void remove_useless_stmts_1 (tree *, struct rus_data *);
1384 remove_useless_stmts_warn_notreached (tree stmt)
1386 if (EXPR_HAS_LOCATION (stmt))
1388 location_t loc = EXPR_LOCATION (stmt);
1389 if (LOCATION_LINE (loc) > 0)
1391 warning (0, "%Hwill never be executed", &loc);
1396 switch (TREE_CODE (stmt))
1398 case STATEMENT_LIST:
1400 tree_stmt_iterator i;
1401 for (i = tsi_start (stmt); !tsi_end_p (i); tsi_next (&i))
1402 if (remove_useless_stmts_warn_notreached (tsi_stmt (i)))
1408 if (remove_useless_stmts_warn_notreached (COND_EXPR_COND (stmt)))
1410 if (remove_useless_stmts_warn_notreached (COND_EXPR_THEN (stmt)))
1412 if (remove_useless_stmts_warn_notreached (COND_EXPR_ELSE (stmt)))
1416 case TRY_FINALLY_EXPR:
1417 case TRY_CATCH_EXPR:
1418 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt, 0)))
1420 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt, 1)))
1425 return remove_useless_stmts_warn_notreached (CATCH_BODY (stmt));
1426 case EH_FILTER_EXPR:
1427 return remove_useless_stmts_warn_notreached (EH_FILTER_FAILURE (stmt));
1429 return remove_useless_stmts_warn_notreached (BIND_EXPR_BLOCK (stmt));
1432 /* Not a live container. */
1440 remove_useless_stmts_cond (tree *stmt_p, struct rus_data *data)
1442 tree then_clause, else_clause, cond;
1443 bool save_has_label, then_has_label, else_has_label;
1445 save_has_label = data->has_label;
1446 data->has_label = false;
1447 data->last_goto = NULL;
1449 remove_useless_stmts_1 (&COND_EXPR_THEN (*stmt_p), data);
1451 then_has_label = data->has_label;
1452 data->has_label = false;
1453 data->last_goto = NULL;
1455 remove_useless_stmts_1 (&COND_EXPR_ELSE (*stmt_p), data);
1457 else_has_label = data->has_label;
1458 data->has_label = save_has_label | then_has_label | else_has_label;
1460 then_clause = COND_EXPR_THEN (*stmt_p);
1461 else_clause = COND_EXPR_ELSE (*stmt_p);
1462 cond = fold (COND_EXPR_COND (*stmt_p));
1464 /* If neither arm does anything at all, we can remove the whole IF. */
1465 if (!TREE_SIDE_EFFECTS (then_clause) && !TREE_SIDE_EFFECTS (else_clause))
1467 *stmt_p = build_empty_stmt ();
1468 data->repeat = true;
1471 /* If there are no reachable statements in an arm, then we can
1472 zap the entire conditional. */
1473 else if (integer_nonzerop (cond) && !else_has_label)
1475 if (warn_notreached)
1476 remove_useless_stmts_warn_notreached (else_clause);
1477 *stmt_p = then_clause;
1478 data->repeat = true;
1480 else if (integer_zerop (cond) && !then_has_label)
1482 if (warn_notreached)
1483 remove_useless_stmts_warn_notreached (then_clause);
1484 *stmt_p = else_clause;
1485 data->repeat = true;
1488 /* Check a couple of simple things on then/else with single stmts. */
1491 tree then_stmt = expr_only (then_clause);
1492 tree else_stmt = expr_only (else_clause);
1494 /* Notice branches to a common destination. */
1495 if (then_stmt && else_stmt
1496 && TREE_CODE (then_stmt) == GOTO_EXPR
1497 && TREE_CODE (else_stmt) == GOTO_EXPR
1498 && (GOTO_DESTINATION (then_stmt) == GOTO_DESTINATION (else_stmt)))
1500 *stmt_p = then_stmt;
1501 data->repeat = true;
1504 /* If the THEN/ELSE clause merely assigns a value to a variable or
1505 parameter which is already known to contain that value, then
1506 remove the useless THEN/ELSE clause. */
1507 else if (TREE_CODE (cond) == VAR_DECL || TREE_CODE (cond) == PARM_DECL)
1510 && TREE_CODE (else_stmt) == MODIFY_EXPR
1511 && TREE_OPERAND (else_stmt, 0) == cond
1512 && integer_zerop (TREE_OPERAND (else_stmt, 1)))
1513 COND_EXPR_ELSE (*stmt_p) = alloc_stmt_list ();
1515 else if ((TREE_CODE (cond) == EQ_EXPR || TREE_CODE (cond) == NE_EXPR)
1516 && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL
1517 || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL)
1518 && TREE_CONSTANT (TREE_OPERAND (cond, 1)))
1520 tree stmt = (TREE_CODE (cond) == EQ_EXPR
1521 ? then_stmt : else_stmt);
1522 tree *location = (TREE_CODE (cond) == EQ_EXPR
1523 ? &COND_EXPR_THEN (*stmt_p)
1524 : &COND_EXPR_ELSE (*stmt_p));
1527 && TREE_CODE (stmt) == MODIFY_EXPR
1528 && TREE_OPERAND (stmt, 0) == TREE_OPERAND (cond, 0)
1529 && TREE_OPERAND (stmt, 1) == TREE_OPERAND (cond, 1))
1530 *location = alloc_stmt_list ();
1534 /* Protect GOTOs in the arm of COND_EXPRs from being removed. They
1535 would be re-introduced during lowering. */
1536 data->last_goto = NULL;
1541 remove_useless_stmts_tf (tree *stmt_p, struct rus_data *data)
1543 bool save_may_branch, save_may_throw;
1544 bool this_may_branch, this_may_throw;
1546 /* Collect may_branch and may_throw information for the body only. */
1547 save_may_branch = data->may_branch;
1548 save_may_throw = data->may_throw;
1549 data->may_branch = false;
1550 data->may_throw = false;
1551 data->last_goto = NULL;
1553 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 0), data);
1555 this_may_branch = data->may_branch;
1556 this_may_throw = data->may_throw;
1557 data->may_branch |= save_may_branch;
1558 data->may_throw |= save_may_throw;
1559 data->last_goto = NULL;
1561 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 1), data);
1563 /* If the body is empty, then we can emit the FINALLY block without
1564 the enclosing TRY_FINALLY_EXPR. */
1565 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 0)))
1567 *stmt_p = TREE_OPERAND (*stmt_p, 1);
1568 data->repeat = true;
1571 /* If the handler is empty, then we can emit the TRY block without
1572 the enclosing TRY_FINALLY_EXPR. */
1573 else if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 1)))
1575 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1576 data->repeat = true;
1579 /* If the body neither throws, nor branches, then we can safely
1580 string the TRY and FINALLY blocks together. */
1581 else if (!this_may_branch && !this_may_throw)
1583 tree stmt = *stmt_p;
1584 *stmt_p = TREE_OPERAND (stmt, 0);
1585 append_to_statement_list (TREE_OPERAND (stmt, 1), stmt_p);
1586 data->repeat = true;
1592 remove_useless_stmts_tc (tree *stmt_p, struct rus_data *data)
1594 bool save_may_throw, this_may_throw;
1595 tree_stmt_iterator i;
1598 /* Collect may_throw information for the body only. */
1599 save_may_throw = data->may_throw;
1600 data->may_throw = false;
1601 data->last_goto = NULL;
1603 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 0), data);
1605 this_may_throw = data->may_throw;
1606 data->may_throw = save_may_throw;
1608 /* If the body cannot throw, then we can drop the entire TRY_CATCH_EXPR. */
1609 if (!this_may_throw)
1611 if (warn_notreached)
1612 remove_useless_stmts_warn_notreached (TREE_OPERAND (*stmt_p, 1));
1613 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1614 data->repeat = true;
1618 /* Process the catch clause specially. We may be able to tell that
1619 no exceptions propagate past this point. */
1621 this_may_throw = true;
1622 i = tsi_start (TREE_OPERAND (*stmt_p, 1));
1623 stmt = tsi_stmt (i);
1624 data->last_goto = NULL;
1626 switch (TREE_CODE (stmt))
1629 for (; !tsi_end_p (i); tsi_next (&i))
1631 stmt = tsi_stmt (i);
1632 /* If we catch all exceptions, then the body does not
1633 propagate exceptions past this point. */
1634 if (CATCH_TYPES (stmt) == NULL)
1635 this_may_throw = false;
1636 data->last_goto = NULL;
1637 remove_useless_stmts_1 (&CATCH_BODY (stmt), data);
1641 case EH_FILTER_EXPR:
1642 if (EH_FILTER_MUST_NOT_THROW (stmt))
1643 this_may_throw = false;
1644 else if (EH_FILTER_TYPES (stmt) == NULL)
1645 this_may_throw = false;
1646 remove_useless_stmts_1 (&EH_FILTER_FAILURE (stmt), data);
1650 /* Otherwise this is a cleanup. */
1651 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 1), data);
1653 /* If the cleanup is empty, then we can emit the TRY block without
1654 the enclosing TRY_CATCH_EXPR. */
1655 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 1)))
1657 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1658 data->repeat = true;
1662 data->may_throw |= this_may_throw;
1667 remove_useless_stmts_bind (tree *stmt_p, struct rus_data *data)
1671 /* First remove anything underneath the BIND_EXPR. */
1672 remove_useless_stmts_1 (&BIND_EXPR_BODY (*stmt_p), data);
1674 /* If the BIND_EXPR has no variables, then we can pull everything
1675 up one level and remove the BIND_EXPR, unless this is the toplevel
1676 BIND_EXPR for the current function or an inlined function.
1678 When this situation occurs we will want to apply this
1679 optimization again. */
1680 block = BIND_EXPR_BLOCK (*stmt_p);
1681 if (BIND_EXPR_VARS (*stmt_p) == NULL_TREE
1682 && *stmt_p != DECL_SAVED_TREE (current_function_decl)
1684 || ! BLOCK_ABSTRACT_ORIGIN (block)
1685 || (TREE_CODE (BLOCK_ABSTRACT_ORIGIN (block))
1688 *stmt_p = BIND_EXPR_BODY (*stmt_p);
1689 data->repeat = true;
1695 remove_useless_stmts_goto (tree *stmt_p, struct rus_data *data)
1697 tree dest = GOTO_DESTINATION (*stmt_p);
1699 data->may_branch = true;
1700 data->last_goto = NULL;
1702 /* Record the last goto expr, so that we can delete it if unnecessary. */
1703 if (TREE_CODE (dest) == LABEL_DECL)
1704 data->last_goto = stmt_p;
1709 remove_useless_stmts_label (tree *stmt_p, struct rus_data *data)
1711 tree label = LABEL_EXPR_LABEL (*stmt_p);
1713 data->has_label = true;
1715 /* We do want to jump across non-local label receiver code. */
1716 if (DECL_NONLOCAL (label))
1717 data->last_goto = NULL;
1719 else if (data->last_goto && GOTO_DESTINATION (*data->last_goto) == label)
1721 *data->last_goto = build_empty_stmt ();
1722 data->repeat = true;
1725 /* ??? Add something here to delete unused labels. */
1729 /* If the function is "const" or "pure", then clear TREE_SIDE_EFFECTS on its
1730 decl. This allows us to eliminate redundant or useless
1731 calls to "const" functions.
1733 Gimplifier already does the same operation, but we may notice functions
1734 being const and pure once their calls has been gimplified, so we need
1735 to update the flag. */
1738 update_call_expr_flags (tree call)
1740 tree decl = get_callee_fndecl (call);
1743 if (call_expr_flags (call) & (ECF_CONST | ECF_PURE))
1744 TREE_SIDE_EFFECTS (call) = 0;
1745 if (TREE_NOTHROW (decl))
1746 TREE_NOTHROW (call) = 1;
1750 /* T is CALL_EXPR. Set current_function_calls_* flags. */
1753 notice_special_calls (tree t)
1755 int flags = call_expr_flags (t);
1757 if (flags & ECF_MAY_BE_ALLOCA)
1758 current_function_calls_alloca = true;
1759 if (flags & ECF_RETURNS_TWICE)
1760 current_function_calls_setjmp = true;
1764 /* Clear flags set by notice_special_calls. Used by dead code removal
1765 to update the flags. */
1768 clear_special_calls (void)
1770 current_function_calls_alloca = false;
1771 current_function_calls_setjmp = false;
1776 remove_useless_stmts_1 (tree *tp, struct rus_data *data)
1780 switch (TREE_CODE (t))
1783 remove_useless_stmts_cond (tp, data);
1786 case TRY_FINALLY_EXPR:
1787 remove_useless_stmts_tf (tp, data);
1790 case TRY_CATCH_EXPR:
1791 remove_useless_stmts_tc (tp, data);
1795 remove_useless_stmts_bind (tp, data);
1799 remove_useless_stmts_goto (tp, data);
1803 remove_useless_stmts_label (tp, data);
1808 data->last_goto = NULL;
1809 data->may_branch = true;
1814 data->last_goto = NULL;
1815 notice_special_calls (t);
1816 update_call_expr_flags (t);
1817 if (tree_could_throw_p (t))
1818 data->may_throw = true;
1822 data->last_goto = NULL;
1824 op = get_call_expr_in (t);
1827 update_call_expr_flags (op);
1828 notice_special_calls (op);
1830 if (tree_could_throw_p (t))
1831 data->may_throw = true;
1834 case STATEMENT_LIST:
1836 tree_stmt_iterator i = tsi_start (t);
1837 while (!tsi_end_p (i))
1840 if (IS_EMPTY_STMT (t))
1846 remove_useless_stmts_1 (tsi_stmt_ptr (i), data);
1849 if (TREE_CODE (t) == STATEMENT_LIST)
1851 tsi_link_before (&i, t, TSI_SAME_STMT);
1861 data->last_goto = NULL;
1865 data->last_goto = NULL;
1871 remove_useless_stmts (void)
1873 struct rus_data data;
1875 clear_special_calls ();
1879 memset (&data, 0, sizeof (data));
1880 remove_useless_stmts_1 (&DECL_SAVED_TREE (current_function_decl), &data);
1882 while (data.repeat);
1886 struct tree_opt_pass pass_remove_useless_stmts =
1888 "useless", /* name */
1890 remove_useless_stmts, /* execute */
1893 0, /* static_pass_number */
1895 PROP_gimple_any, /* properties_required */
1896 0, /* properties_provided */
1897 0, /* properties_destroyed */
1898 0, /* todo_flags_start */
1899 TODO_dump_func, /* todo_flags_finish */
1903 /* Remove PHI nodes associated with basic block BB and all edges out of BB. */
1906 remove_phi_nodes_and_edges_for_unreachable_block (basic_block bb)
1910 /* Since this block is no longer reachable, we can just delete all
1911 of its PHI nodes. */
1912 phi = phi_nodes (bb);
1915 tree next = PHI_CHAIN (phi);
1916 remove_phi_node (phi, NULL_TREE);
1920 /* Remove edges to BB's successors. */
1921 while (EDGE_COUNT (bb->succs) > 0)
1922 remove_edge (EDGE_SUCC (bb, 0));
1926 /* Remove statements of basic block BB. */
1929 remove_bb (basic_block bb)
1931 block_stmt_iterator i;
1932 #ifdef USE_MAPPED_LOCATION
1933 source_location loc = UNKNOWN_LOCATION;
1935 source_locus loc = 0;
1940 fprintf (dump_file, "Removing basic block %d\n", bb->index);
1941 if (dump_flags & TDF_DETAILS)
1943 dump_bb (bb, dump_file, 0);
1944 fprintf (dump_file, "\n");
1948 /* If we remove the header or the latch of a loop, mark the loop for
1949 removal by setting its header and latch to NULL. */
1952 struct loop *loop = bb->loop_father;
1954 if (loop->latch == bb
1955 || loop->header == bb)
1958 loop->header = NULL;
1962 /* Remove all the instructions in the block. */
1963 for (i = bsi_start (bb); !bsi_end_p (i);)
1965 tree stmt = bsi_stmt (i);
1966 if (TREE_CODE (stmt) == LABEL_EXPR
1967 && FORCED_LABEL (LABEL_EXPR_LABEL (stmt)))
1969 basic_block new_bb = bb->prev_bb;
1970 block_stmt_iterator new_bsi = bsi_start (new_bb);
1973 bsi_insert_before (&new_bsi, stmt, BSI_NEW_STMT);
1977 release_defs (stmt);
1982 /* Don't warn for removed gotos. Gotos are often removed due to
1983 jump threading, thus resulting in bogus warnings. Not great,
1984 since this way we lose warnings for gotos in the original
1985 program that are indeed unreachable. */
1986 if (TREE_CODE (stmt) != GOTO_EXPR && EXPR_HAS_LOCATION (stmt) && !loc)
1988 #ifdef USE_MAPPED_LOCATION
1989 if (EXPR_HAS_LOCATION (stmt))
1990 loc = EXPR_LOCATION (stmt);
1993 t = EXPR_LOCUS (stmt);
1994 if (t && LOCATION_LINE (*t) > 0)
2000 /* If requested, give a warning that the first statement in the
2001 block is unreachable. We walk statements backwards in the
2002 loop above, so the last statement we process is the first statement
2004 #ifdef USE_MAPPED_LOCATION
2005 if (warn_notreached && loc > BUILTINS_LOCATION)
2006 warning (0, "%Hwill never be executed", &loc);
2008 if (warn_notreached && loc)
2009 warning (0, "%Hwill never be executed", loc);
2012 remove_phi_nodes_and_edges_for_unreachable_block (bb);
2015 /* A list of all the noreturn calls passed to modify_stmt.
2016 cleanup_control_flow uses it to detect cases where a mid-block
2017 indirect call has been turned into a noreturn call. When this
2018 happens, all the instructions after the call are no longer
2019 reachable and must be deleted as dead. */
2021 VEC(tree,gc) *modified_noreturn_calls;
2023 /* Try to remove superfluous control structures. */
2026 cleanup_control_flow (void)
2029 block_stmt_iterator bsi;
2030 bool retval = false;
2033 /* Detect cases where a mid-block call is now known not to return. */
2034 while (VEC_length (tree, modified_noreturn_calls))
2036 stmt = VEC_pop (tree, modified_noreturn_calls);
2037 bb = bb_for_stmt (stmt);
2038 if (bb != NULL && last_stmt (bb) != stmt && noreturn_call_p (stmt))
2039 split_block (bb, stmt);
2044 bsi = bsi_last (bb);
2046 if (bsi_end_p (bsi))
2049 stmt = bsi_stmt (bsi);
2050 if (TREE_CODE (stmt) == COND_EXPR
2051 || TREE_CODE (stmt) == SWITCH_EXPR)
2052 retval |= cleanup_control_expr_graph (bb, bsi);
2054 /* If we had a computed goto which has a compile-time determinable
2055 destination, then we can eliminate the goto. */
2056 if (TREE_CODE (stmt) == GOTO_EXPR
2057 && TREE_CODE (GOTO_DESTINATION (stmt)) == ADDR_EXPR
2058 && TREE_CODE (TREE_OPERAND (GOTO_DESTINATION (stmt), 0)) == LABEL_DECL)
2063 basic_block target_block;
2064 bool removed_edge = false;
2066 /* First look at all the outgoing edges. Delete any outgoing
2067 edges which do not go to the right block. For the one
2068 edge which goes to the right block, fix up its flags. */
2069 label = TREE_OPERAND (GOTO_DESTINATION (stmt), 0);
2070 target_block = label_to_block (label);
2071 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2073 if (e->dest != target_block)
2075 removed_edge = true;
2080 /* Turn off the EDGE_ABNORMAL flag. */
2081 e->flags &= ~EDGE_ABNORMAL;
2083 /* And set EDGE_FALLTHRU. */
2084 e->flags |= EDGE_FALLTHRU;
2089 /* If we removed one or more edges, then we will need to fix the
2090 dominators. It may be possible to incrementally update them. */
2092 free_dominance_info (CDI_DOMINATORS);
2094 /* Remove the GOTO_EXPR as it is not needed. The CFG has all the
2095 relevant information we need. */
2100 /* Check for indirect calls that have been turned into
2102 if (noreturn_call_p (stmt) && remove_fallthru_edge (bb->succs))
2104 free_dominance_info (CDI_DOMINATORS);
2112 /* Disconnect an unreachable block in the control expression starting
2116 cleanup_control_expr_graph (basic_block bb, block_stmt_iterator bsi)
2119 bool retval = false;
2120 tree expr = bsi_stmt (bsi), val;
2122 if (!single_succ_p (bb))
2127 switch (TREE_CODE (expr))
2130 val = COND_EXPR_COND (expr);
2134 val = SWITCH_COND (expr);
2135 if (TREE_CODE (val) != INTEGER_CST)
2143 taken_edge = find_taken_edge (bb, val);
2147 /* Remove all the edges except the one that is always executed. */
2148 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2150 if (e != taken_edge)
2152 taken_edge->probability += e->probability;
2153 taken_edge->count += e->count;
2160 if (taken_edge->probability > REG_BR_PROB_BASE)
2161 taken_edge->probability = REG_BR_PROB_BASE;
2164 taken_edge = single_succ_edge (bb);
2167 taken_edge->flags = EDGE_FALLTHRU;
2169 /* We removed some paths from the cfg. */
2170 free_dominance_info (CDI_DOMINATORS);
2175 /* Remove any fallthru edge from EV. Return true if an edge was removed. */
2178 remove_fallthru_edge (VEC(edge,gc) *ev)
2183 FOR_EACH_EDGE (e, ei, ev)
2184 if ((e->flags & EDGE_FALLTHRU) != 0)
2192 /* Given a basic block BB ending with COND_EXPR or SWITCH_EXPR, and a
2193 predicate VAL, return the edge that will be taken out of the block.
2194 If VAL does not match a unique edge, NULL is returned. */
2197 find_taken_edge (basic_block bb, tree val)
2201 stmt = last_stmt (bb);
2204 gcc_assert (is_ctrl_stmt (stmt));
2207 if (! is_gimple_min_invariant (val))
2210 if (TREE_CODE (stmt) == COND_EXPR)
2211 return find_taken_edge_cond_expr (bb, val);
2213 if (TREE_CODE (stmt) == SWITCH_EXPR)
2214 return find_taken_edge_switch_expr (bb, val);
2216 if (computed_goto_p (stmt))
2217 return find_taken_edge_computed_goto (bb, TREE_OPERAND( val, 0));
2222 /* Given a constant value VAL and the entry block BB to a GOTO_EXPR
2223 statement, determine which of the outgoing edges will be taken out of the
2224 block. Return NULL if either edge may be taken. */
2227 find_taken_edge_computed_goto (basic_block bb, tree val)
2232 dest = label_to_block (val);
2235 e = find_edge (bb, dest);
2236 gcc_assert (e != NULL);
2242 /* Given a constant value VAL and the entry block BB to a COND_EXPR
2243 statement, determine which of the two edges will be taken out of the
2244 block. Return NULL if either edge may be taken. */
2247 find_taken_edge_cond_expr (basic_block bb, tree val)
2249 edge true_edge, false_edge;
2251 extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
2253 gcc_assert (TREE_CODE (val) == INTEGER_CST);
2254 return (zero_p (val) ? false_edge : true_edge);
2257 /* Given an INTEGER_CST VAL and the entry block BB to a SWITCH_EXPR
2258 statement, determine which edge will be taken out of the block. Return
2259 NULL if any edge may be taken. */
2262 find_taken_edge_switch_expr (basic_block bb, tree val)
2264 tree switch_expr, taken_case;
2265 basic_block dest_bb;
2268 switch_expr = last_stmt (bb);
2269 taken_case = find_case_label_for_value (switch_expr, val);
2270 dest_bb = label_to_block (CASE_LABEL (taken_case));
2272 e = find_edge (bb, dest_bb);
2278 /* Return the CASE_LABEL_EXPR that SWITCH_EXPR will take for VAL.
2279 We can make optimal use here of the fact that the case labels are
2280 sorted: We can do a binary search for a case matching VAL. */
2283 find_case_label_for_value (tree switch_expr, tree val)
2285 tree vec = SWITCH_LABELS (switch_expr);
2286 size_t low, high, n = TREE_VEC_LENGTH (vec);
2287 tree default_case = TREE_VEC_ELT (vec, n - 1);
2289 for (low = -1, high = n - 1; high - low > 1; )
2291 size_t i = (high + low) / 2;
2292 tree t = TREE_VEC_ELT (vec, i);
2295 /* Cache the result of comparing CASE_LOW and val. */
2296 cmp = tree_int_cst_compare (CASE_LOW (t), val);
2303 if (CASE_HIGH (t) == NULL)
2305 /* A singe-valued case label. */
2311 /* A case range. We can only handle integer ranges. */
2312 if (cmp <= 0 && tree_int_cst_compare (CASE_HIGH (t), val) >= 0)
2317 return default_case;
2321 /* If all the PHI nodes in DEST have alternatives for E1 and E2 and
2322 those alternatives are equal in each of the PHI nodes, then return
2323 true, else return false. */
2326 phi_alternatives_equal (basic_block dest, edge e1, edge e2)
2328 int n1 = e1->dest_idx;
2329 int n2 = e2->dest_idx;
2332 for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi))
2334 tree val1 = PHI_ARG_DEF (phi, n1);
2335 tree val2 = PHI_ARG_DEF (phi, n2);
2337 gcc_assert (val1 != NULL_TREE);
2338 gcc_assert (val2 != NULL_TREE);
2340 if (!operand_equal_for_phi_arg_p (val1, val2))
2348 /*---------------------------------------------------------------------------
2350 ---------------------------------------------------------------------------*/
2352 /* Dump tree-specific information of block BB to file OUTF. */
2355 tree_dump_bb (basic_block bb, FILE *outf, int indent)
2357 dump_generic_bb (outf, bb, indent, TDF_VOPS);
2361 /* Dump a basic block on stderr. */
2364 debug_tree_bb (basic_block bb)
2366 dump_bb (bb, stderr, 0);
2370 /* Dump basic block with index N on stderr. */
2373 debug_tree_bb_n (int n)
2375 debug_tree_bb (BASIC_BLOCK (n));
2376 return BASIC_BLOCK (n);
2380 /* Dump the CFG on stderr.
2382 FLAGS are the same used by the tree dumping functions
2383 (see TDF_* in tree.h). */
2386 debug_tree_cfg (int flags)
2388 dump_tree_cfg (stderr, flags);
2392 /* Dump the program showing basic block boundaries on the given FILE.
2394 FLAGS are the same used by the tree dumping functions (see TDF_* in
2398 dump_tree_cfg (FILE *file, int flags)
2400 if (flags & TDF_DETAILS)
2402 const char *funcname
2403 = lang_hooks.decl_printable_name (current_function_decl, 2);
2406 fprintf (file, ";; Function %s\n\n", funcname);
2407 fprintf (file, ";; \n%d basic blocks, %d edges, last basic block %d.\n\n",
2408 n_basic_blocks, n_edges, last_basic_block);
2410 brief_dump_cfg (file);
2411 fprintf (file, "\n");
2414 if (flags & TDF_STATS)
2415 dump_cfg_stats (file);
2417 dump_function_to_file (current_function_decl, file, flags | TDF_BLOCKS);
2421 /* Dump CFG statistics on FILE. */
2424 dump_cfg_stats (FILE *file)
2426 static long max_num_merged_labels = 0;
2427 unsigned long size, total = 0;
2430 const char * const fmt_str = "%-30s%-13s%12s\n";
2431 const char * const fmt_str_1 = "%-30s%13d%11lu%c\n";
2432 const char * const fmt_str_3 = "%-43s%11lu%c\n";
2433 const char *funcname
2434 = lang_hooks.decl_printable_name (current_function_decl, 2);
2437 fprintf (file, "\nCFG Statistics for %s\n\n", funcname);
2439 fprintf (file, "---------------------------------------------------------\n");
2440 fprintf (file, fmt_str, "", " Number of ", "Memory");
2441 fprintf (file, fmt_str, "", " instances ", "used ");
2442 fprintf (file, "---------------------------------------------------------\n");
2444 size = n_basic_blocks * sizeof (struct basic_block_def);
2446 fprintf (file, fmt_str_1, "Basic blocks", n_basic_blocks,
2447 SCALE (size), LABEL (size));
2451 num_edges += EDGE_COUNT (bb->succs);
2452 size = num_edges * sizeof (struct edge_def);
2454 fprintf (file, fmt_str_1, "Edges", num_edges, SCALE (size), LABEL (size));
2456 size = n_basic_blocks * sizeof (struct bb_ann_d);
2458 fprintf (file, fmt_str_1, "Basic block annotations", n_basic_blocks,
2459 SCALE (size), LABEL (size));
2461 fprintf (file, "---------------------------------------------------------\n");
2462 fprintf (file, fmt_str_3, "Total memory used by CFG data", SCALE (total),
2464 fprintf (file, "---------------------------------------------------------\n");
2465 fprintf (file, "\n");
2467 if (cfg_stats.num_merged_labels > max_num_merged_labels)
2468 max_num_merged_labels = cfg_stats.num_merged_labels;
2470 fprintf (file, "Coalesced label blocks: %ld (Max so far: %ld)\n",
2471 cfg_stats.num_merged_labels, max_num_merged_labels);
2473 fprintf (file, "\n");
2477 /* Dump CFG statistics on stderr. Keep extern so that it's always
2478 linked in the final executable. */
2481 debug_cfg_stats (void)
2483 dump_cfg_stats (stderr);
2487 /* Dump the flowgraph to a .vcg FILE. */
2490 tree_cfg2vcg (FILE *file)
2495 const char *funcname
2496 = lang_hooks.decl_printable_name (current_function_decl, 2);
2498 /* Write the file header. */
2499 fprintf (file, "graph: { title: \"%s\"\n", funcname);
2500 fprintf (file, "node: { title: \"ENTRY\" label: \"ENTRY\" }\n");
2501 fprintf (file, "node: { title: \"EXIT\" label: \"EXIT\" }\n");
2503 /* Write blocks and edges. */
2504 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
2506 fprintf (file, "edge: { sourcename: \"ENTRY\" targetname: \"%d\"",
2509 if (e->flags & EDGE_FAKE)
2510 fprintf (file, " linestyle: dotted priority: 10");
2512 fprintf (file, " linestyle: solid priority: 100");
2514 fprintf (file, " }\n");
2520 enum tree_code head_code, end_code;
2521 const char *head_name, *end_name;
2524 tree first = first_stmt (bb);
2525 tree last = last_stmt (bb);
2529 head_code = TREE_CODE (first);
2530 head_name = tree_code_name[head_code];
2531 head_line = get_lineno (first);
2534 head_name = "no-statement";
2538 end_code = TREE_CODE (last);
2539 end_name = tree_code_name[end_code];
2540 end_line = get_lineno (last);
2543 end_name = "no-statement";
2545 fprintf (file, "node: { title: \"%d\" label: \"#%d\\n%s (%d)\\n%s (%d)\"}\n",
2546 bb->index, bb->index, head_name, head_line, end_name,
2549 FOR_EACH_EDGE (e, ei, bb->succs)
2551 if (e->dest == EXIT_BLOCK_PTR)
2552 fprintf (file, "edge: { sourcename: \"%d\" targetname: \"EXIT\"", bb->index);
2554 fprintf (file, "edge: { sourcename: \"%d\" targetname: \"%d\"", bb->index, e->dest->index);
2556 if (e->flags & EDGE_FAKE)
2557 fprintf (file, " priority: 10 linestyle: dotted");
2559 fprintf (file, " priority: 100 linestyle: solid");
2561 fprintf (file, " }\n");
2564 if (bb->next_bb != EXIT_BLOCK_PTR)
2568 fputs ("}\n\n", file);
2573 /*---------------------------------------------------------------------------
2574 Miscellaneous helpers
2575 ---------------------------------------------------------------------------*/
2577 /* Return true if T represents a stmt that always transfers control. */
2580 is_ctrl_stmt (tree t)
2582 return (TREE_CODE (t) == COND_EXPR
2583 || TREE_CODE (t) == SWITCH_EXPR
2584 || TREE_CODE (t) == GOTO_EXPR
2585 || TREE_CODE (t) == RETURN_EXPR
2586 || TREE_CODE (t) == RESX_EXPR);
2590 /* Return true if T is a statement that may alter the flow of control
2591 (e.g., a call to a non-returning function). */
2594 is_ctrl_altering_stmt (tree t)
2599 call = get_call_expr_in (t);
2602 /* A non-pure/const CALL_EXPR alters flow control if the current
2603 function has nonlocal labels. */
2604 if (TREE_SIDE_EFFECTS (call) && current_function_has_nonlocal_label)
2607 /* A CALL_EXPR also alters control flow if it does not return. */
2608 if (call_expr_flags (call) & ECF_NORETURN)
2612 /* If a statement can throw, it alters control flow. */
2613 return tree_can_throw_internal (t);
2617 /* Return true if T is a computed goto. */
2620 computed_goto_p (tree t)
2622 return (TREE_CODE (t) == GOTO_EXPR
2623 && TREE_CODE (GOTO_DESTINATION (t)) != LABEL_DECL);
2627 /* Checks whether EXPR is a simple local goto. */
2630 simple_goto_p (tree expr)
2632 return (TREE_CODE (expr) == GOTO_EXPR
2633 && TREE_CODE (GOTO_DESTINATION (expr)) == LABEL_DECL);
2637 /* Return true if T should start a new basic block. PREV_T is the
2638 statement preceding T. It is used when T is a label or a case label.
2639 Labels should only start a new basic block if their previous statement
2640 wasn't a label. Otherwise, sequence of labels would generate
2641 unnecessary basic blocks that only contain a single label. */
2644 stmt_starts_bb_p (tree t, tree prev_t)
2649 /* LABEL_EXPRs start a new basic block only if the preceding
2650 statement wasn't a label of the same type. This prevents the
2651 creation of consecutive blocks that have nothing but a single
2653 if (TREE_CODE (t) == LABEL_EXPR)
2655 /* Nonlocal and computed GOTO targets always start a new block. */
2656 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (t))
2657 || FORCED_LABEL (LABEL_EXPR_LABEL (t)))
2660 if (prev_t && TREE_CODE (prev_t) == LABEL_EXPR)
2662 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (prev_t)))
2665 cfg_stats.num_merged_labels++;
2676 /* Return true if T should end a basic block. */
2679 stmt_ends_bb_p (tree t)
2681 return is_ctrl_stmt (t) || is_ctrl_altering_stmt (t);
2685 /* Add gotos that used to be represented implicitly in the CFG. */
2688 disband_implicit_edges (void)
2691 block_stmt_iterator last;
2698 last = bsi_last (bb);
2699 stmt = last_stmt (bb);
2701 if (stmt && TREE_CODE (stmt) == COND_EXPR)
2703 /* Remove superfluous gotos from COND_EXPR branches. Moved
2704 from cfg_remove_useless_stmts here since it violates the
2705 invariants for tree--cfg correspondence and thus fits better
2706 here where we do it anyway. */
2707 e = find_edge (bb, bb->next_bb);
2710 if (e->flags & EDGE_TRUE_VALUE)
2711 COND_EXPR_THEN (stmt) = build_empty_stmt ();
2712 else if (e->flags & EDGE_FALSE_VALUE)
2713 COND_EXPR_ELSE (stmt) = build_empty_stmt ();
2716 e->flags |= EDGE_FALLTHRU;
2722 if (stmt && TREE_CODE (stmt) == RETURN_EXPR)
2724 /* Remove the RETURN_EXPR if we may fall though to the exit
2726 gcc_assert (single_succ_p (bb));
2727 gcc_assert (single_succ (bb) == EXIT_BLOCK_PTR);
2729 if (bb->next_bb == EXIT_BLOCK_PTR
2730 && !TREE_OPERAND (stmt, 0))
2733 single_succ_edge (bb)->flags |= EDGE_FALLTHRU;
2738 /* There can be no fallthru edge if the last statement is a control
2740 if (stmt && is_ctrl_stmt (stmt))
2743 /* Find a fallthru edge and emit the goto if necessary. */
2744 FOR_EACH_EDGE (e, ei, bb->succs)
2745 if (e->flags & EDGE_FALLTHRU)
2748 if (!e || e->dest == bb->next_bb)
2751 gcc_assert (e->dest != EXIT_BLOCK_PTR);
2752 label = tree_block_label (e->dest);
2754 stmt = build1 (GOTO_EXPR, void_type_node, label);
2755 #ifdef USE_MAPPED_LOCATION
2756 SET_EXPR_LOCATION (stmt, e->goto_locus);
2758 SET_EXPR_LOCUS (stmt, e->goto_locus);
2760 bsi_insert_after (&last, stmt, BSI_NEW_STMT);
2761 e->flags &= ~EDGE_FALLTHRU;
2765 /* Remove block annotations and other datastructures. */
2768 delete_tree_cfg_annotations (void)
2771 if (n_basic_blocks > 0)
2772 free_blocks_annotations ();
2774 label_to_block_map = NULL;
2780 /* Return the first statement in basic block BB. */
2783 first_stmt (basic_block bb)
2785 block_stmt_iterator i = bsi_start (bb);
2786 return !bsi_end_p (i) ? bsi_stmt (i) : NULL_TREE;
2790 /* Return the last statement in basic block BB. */
2793 last_stmt (basic_block bb)
2795 block_stmt_iterator b = bsi_last (bb);
2796 return !bsi_end_p (b) ? bsi_stmt (b) : NULL_TREE;
2800 /* Return a pointer to the last statement in block BB. */
2803 last_stmt_ptr (basic_block bb)
2805 block_stmt_iterator last = bsi_last (bb);
2806 return !bsi_end_p (last) ? bsi_stmt_ptr (last) : NULL;
2810 /* Return the last statement of an otherwise empty block. Return NULL
2811 if the block is totally empty, or if it contains more than one
2815 last_and_only_stmt (basic_block bb)
2817 block_stmt_iterator i = bsi_last (bb);
2823 last = bsi_stmt (i);
2828 /* Empty statements should no longer appear in the instruction stream.
2829 Everything that might have appeared before should be deleted by
2830 remove_useless_stmts, and the optimizers should just bsi_remove
2831 instead of smashing with build_empty_stmt.
2833 Thus the only thing that should appear here in a block containing
2834 one executable statement is a label. */
2835 prev = bsi_stmt (i);
2836 if (TREE_CODE (prev) == LABEL_EXPR)
2843 /* Mark BB as the basic block holding statement T. */
2846 set_bb_for_stmt (tree t, basic_block bb)
2848 if (TREE_CODE (t) == PHI_NODE)
2850 else if (TREE_CODE (t) == STATEMENT_LIST)
2852 tree_stmt_iterator i;
2853 for (i = tsi_start (t); !tsi_end_p (i); tsi_next (&i))
2854 set_bb_for_stmt (tsi_stmt (i), bb);
2858 stmt_ann_t ann = get_stmt_ann (t);
2861 /* If the statement is a label, add the label to block-to-labels map
2862 so that we can speed up edge creation for GOTO_EXPRs. */
2863 if (TREE_CODE (t) == LABEL_EXPR)
2867 t = LABEL_EXPR_LABEL (t);
2868 uid = LABEL_DECL_UID (t);
2871 LABEL_DECL_UID (t) = uid = cfun->last_label_uid++;
2872 if (VARRAY_SIZE (label_to_block_map) <= (unsigned) uid)
2873 VARRAY_GROW (label_to_block_map, 3 * uid / 2);
2876 /* We're moving an existing label. Make sure that we've
2877 removed it from the old block. */
2878 gcc_assert (!bb || !VARRAY_BB (label_to_block_map, uid));
2879 VARRAY_BB (label_to_block_map, uid) = bb;
2884 /* Finds iterator for STMT. */
2886 extern block_stmt_iterator
2887 bsi_for_stmt (tree stmt)
2889 block_stmt_iterator bsi;
2891 for (bsi = bsi_start (bb_for_stmt (stmt)); !bsi_end_p (bsi); bsi_next (&bsi))
2892 if (bsi_stmt (bsi) == stmt)
2898 /* Mark statement T as modified, and update it. */
2900 update_modified_stmts (tree t)
2902 if (TREE_CODE (t) == STATEMENT_LIST)
2904 tree_stmt_iterator i;
2906 for (i = tsi_start (t); !tsi_end_p (i); tsi_next (&i))
2908 stmt = tsi_stmt (i);
2909 update_stmt_if_modified (stmt);
2913 update_stmt_if_modified (t);
2916 /* Insert statement (or statement list) T before the statement
2917 pointed-to by iterator I. M specifies how to update iterator I
2918 after insertion (see enum bsi_iterator_update). */
2921 bsi_insert_before (block_stmt_iterator *i, tree t, enum bsi_iterator_update m)
2923 set_bb_for_stmt (t, i->bb);
2924 update_modified_stmts (t);
2925 tsi_link_before (&i->tsi, t, m);
2929 /* Insert statement (or statement list) T after the statement
2930 pointed-to by iterator I. M specifies how to update iterator I
2931 after insertion (see enum bsi_iterator_update). */
2934 bsi_insert_after (block_stmt_iterator *i, tree t, enum bsi_iterator_update m)
2936 set_bb_for_stmt (t, i->bb);
2937 update_modified_stmts (t);
2938 tsi_link_after (&i->tsi, t, m);
2942 /* Remove the statement pointed to by iterator I. The iterator is updated
2943 to the next statement. */
2946 bsi_remove (block_stmt_iterator *i)
2948 tree t = bsi_stmt (*i);
2949 set_bb_for_stmt (t, NULL);
2950 delink_stmt_imm_use (t);
2951 tsi_delink (&i->tsi);
2952 mark_stmt_modified (t);
2956 /* Move the statement at FROM so it comes right after the statement at TO. */
2959 bsi_move_after (block_stmt_iterator *from, block_stmt_iterator *to)
2961 tree stmt = bsi_stmt (*from);
2963 bsi_insert_after (to, stmt, BSI_SAME_STMT);
2967 /* Move the statement at FROM so it comes right before the statement at TO. */
2970 bsi_move_before (block_stmt_iterator *from, block_stmt_iterator *to)
2972 tree stmt = bsi_stmt (*from);
2974 bsi_insert_before (to, stmt, BSI_SAME_STMT);
2978 /* Move the statement at FROM to the end of basic block BB. */
2981 bsi_move_to_bb_end (block_stmt_iterator *from, basic_block bb)
2983 block_stmt_iterator last = bsi_last (bb);
2985 /* Have to check bsi_end_p because it could be an empty block. */
2986 if (!bsi_end_p (last) && is_ctrl_stmt (bsi_stmt (last)))
2987 bsi_move_before (from, &last);
2989 bsi_move_after (from, &last);
2993 /* Replace the contents of the statement pointed to by iterator BSI
2994 with STMT. If PRESERVE_EH_INFO is true, the exception handling
2995 information of the original statement is preserved. */
2998 bsi_replace (const block_stmt_iterator *bsi, tree stmt, bool preserve_eh_info)
3001 tree orig_stmt = bsi_stmt (*bsi);
3003 SET_EXPR_LOCUS (stmt, EXPR_LOCUS (orig_stmt));
3004 set_bb_for_stmt (stmt, bsi->bb);
3006 /* Preserve EH region information from the original statement, if
3007 requested by the caller. */
3008 if (preserve_eh_info)
3010 eh_region = lookup_stmt_eh_region (orig_stmt);
3012 add_stmt_to_eh_region (stmt, eh_region);
3015 delink_stmt_imm_use (orig_stmt);
3016 *bsi_stmt_ptr (*bsi) = stmt;
3017 mark_stmt_modified (stmt);
3018 update_modified_stmts (stmt);
3022 /* Insert the statement pointed-to by BSI into edge E. Every attempt
3023 is made to place the statement in an existing basic block, but
3024 sometimes that isn't possible. When it isn't possible, the edge is
3025 split and the statement is added to the new block.
3027 In all cases, the returned *BSI points to the correct location. The
3028 return value is true if insertion should be done after the location,
3029 or false if it should be done before the location. If new basic block
3030 has to be created, it is stored in *NEW_BB. */
3033 tree_find_edge_insert_loc (edge e, block_stmt_iterator *bsi,
3034 basic_block *new_bb)
3036 basic_block dest, src;
3042 /* If the destination has one predecessor which has no PHI nodes,
3043 insert there. Except for the exit block.
3045 The requirement for no PHI nodes could be relaxed. Basically we
3046 would have to examine the PHIs to prove that none of them used
3047 the value set by the statement we want to insert on E. That
3048 hardly seems worth the effort. */
3049 if (single_pred_p (dest)
3050 && ! phi_nodes (dest)
3051 && dest != EXIT_BLOCK_PTR)
3053 *bsi = bsi_start (dest);
3054 if (bsi_end_p (*bsi))
3057 /* Make sure we insert after any leading labels. */
3058 tmp = bsi_stmt (*bsi);
3059 while (TREE_CODE (tmp) == LABEL_EXPR)
3062 if (bsi_end_p (*bsi))
3064 tmp = bsi_stmt (*bsi);
3067 if (bsi_end_p (*bsi))
3069 *bsi = bsi_last (dest);
3076 /* If the source has one successor, the edge is not abnormal and
3077 the last statement does not end a basic block, insert there.
3078 Except for the entry block. */
3080 if ((e->flags & EDGE_ABNORMAL) == 0
3081 && single_succ_p (src)
3082 && src != ENTRY_BLOCK_PTR)
3084 *bsi = bsi_last (src);
3085 if (bsi_end_p (*bsi))
3088 tmp = bsi_stmt (*bsi);
3089 if (!stmt_ends_bb_p (tmp))
3092 /* Insert code just before returning the value. We may need to decompose
3093 the return in the case it contains non-trivial operand. */
3094 if (TREE_CODE (tmp) == RETURN_EXPR)
3096 tree op = TREE_OPERAND (tmp, 0);
3097 if (!is_gimple_val (op))
3099 gcc_assert (TREE_CODE (op) == MODIFY_EXPR);
3100 bsi_insert_before (bsi, op, BSI_NEW_STMT);
3101 TREE_OPERAND (tmp, 0) = TREE_OPERAND (op, 0);
3108 /* Otherwise, create a new basic block, and split this edge. */
3109 dest = split_edge (e);
3112 e = single_pred_edge (dest);
3117 /* This routine will commit all pending edge insertions, creating any new
3118 basic blocks which are necessary. */
3121 bsi_commit_edge_inserts (void)
3127 bsi_commit_one_edge_insert (single_succ_edge (ENTRY_BLOCK_PTR), NULL);
3130 FOR_EACH_EDGE (e, ei, bb->succs)
3131 bsi_commit_one_edge_insert (e, NULL);
3135 /* Commit insertions pending at edge E. If a new block is created, set NEW_BB
3136 to this block, otherwise set it to NULL. */
3139 bsi_commit_one_edge_insert (edge e, basic_block *new_bb)
3143 if (PENDING_STMT (e))
3145 block_stmt_iterator bsi;
3146 tree stmt = PENDING_STMT (e);
3148 PENDING_STMT (e) = NULL_TREE;
3150 if (tree_find_edge_insert_loc (e, &bsi, new_bb))
3151 bsi_insert_after (&bsi, stmt, BSI_NEW_STMT);
3153 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
3158 /* Add STMT to the pending list of edge E. No actual insertion is
3159 made until a call to bsi_commit_edge_inserts () is made. */
3162 bsi_insert_on_edge (edge e, tree stmt)
3164 append_to_statement_list (stmt, &PENDING_STMT (e));
3167 /* Similar to bsi_insert_on_edge+bsi_commit_edge_inserts. If a new
3168 block has to be created, it is returned. */
3171 bsi_insert_on_edge_immediate (edge e, tree stmt)
3173 block_stmt_iterator bsi;
3174 basic_block new_bb = NULL;
3176 gcc_assert (!PENDING_STMT (e));
3178 if (tree_find_edge_insert_loc (e, &bsi, &new_bb))
3179 bsi_insert_after (&bsi, stmt, BSI_NEW_STMT);
3181 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
3186 /*---------------------------------------------------------------------------
3187 Tree specific functions for CFG manipulation
3188 ---------------------------------------------------------------------------*/
3190 /* Reinstall those PHI arguments queued in OLD_EDGE to NEW_EDGE. */
3193 reinstall_phi_args (edge new_edge, edge old_edge)
3197 if (!PENDING_STMT (old_edge))
3200 for (var = PENDING_STMT (old_edge), phi = phi_nodes (new_edge->dest);
3202 var = TREE_CHAIN (var), phi = PHI_CHAIN (phi))
3204 tree result = TREE_PURPOSE (var);
3205 tree arg = TREE_VALUE (var);
3207 gcc_assert (result == PHI_RESULT (phi));
3209 add_phi_arg (phi, arg, new_edge);
3212 PENDING_STMT (old_edge) = NULL;
3215 /* Split a (typically critical) edge EDGE_IN. Return the new block.
3216 Abort on abnormal edges. */
3219 tree_split_edge (edge edge_in)
3221 basic_block new_bb, after_bb, dest, src;
3224 /* Abnormal edges cannot be split. */
3225 gcc_assert (!(edge_in->flags & EDGE_ABNORMAL));
3228 dest = edge_in->dest;
3230 /* Place the new block in the block list. Try to keep the new block
3231 near its "logical" location. This is of most help to humans looking
3232 at debugging dumps. */
3233 if (dest->prev_bb && find_edge (dest->prev_bb, dest))
3234 after_bb = edge_in->src;
3236 after_bb = dest->prev_bb;
3238 new_bb = create_empty_bb (after_bb);
3239 new_bb->frequency = EDGE_FREQUENCY (edge_in);
3240 new_bb->count = edge_in->count;
3241 new_edge = make_edge (new_bb, dest, EDGE_FALLTHRU);
3242 new_edge->probability = REG_BR_PROB_BASE;
3243 new_edge->count = edge_in->count;
3245 e = redirect_edge_and_branch (edge_in, new_bb);
3247 reinstall_phi_args (new_edge, e);
3253 /* Return true when BB has label LABEL in it. */
3256 has_label_p (basic_block bb, tree label)
3258 block_stmt_iterator bsi;
3260 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3262 tree stmt = bsi_stmt (bsi);
3264 if (TREE_CODE (stmt) != LABEL_EXPR)
3266 if (LABEL_EXPR_LABEL (stmt) == label)
3273 /* Callback for walk_tree, check that all elements with address taken are
3274 properly noticed as such. The DATA is an int* that is 1 if TP was seen
3275 inside a PHI node. */
3278 verify_expr (tree *tp, int *walk_subtrees, void *data ATTRIBUTE_UNUSED)
3281 bool in_phi = (data != NULL);
3286 /* Check operand N for being valid GIMPLE and give error MSG if not.
3287 We check for constants explicitly since they are not considered
3288 gimple invariants if they overflowed. */
3289 #define CHECK_OP(N, MSG) \
3290 do { if (!CONSTANT_CLASS_P (TREE_OPERAND (t, N)) \
3291 && !is_gimple_val (TREE_OPERAND (t, N))) \
3292 { error (MSG); return TREE_OPERAND (t, N); }} while (0)
3294 switch (TREE_CODE (t))
3297 if (SSA_NAME_IN_FREE_LIST (t))
3299 error ("SSA name in freelist but still referenced");
3305 x = fold (ASSERT_EXPR_COND (t));
3306 if (x == boolean_false_node)
3308 error ("ASSERT_EXPR with an always-false condition");
3314 x = TREE_OPERAND (t, 0);
3315 if (TREE_CODE (x) == BIT_FIELD_REF
3316 && is_gimple_reg (TREE_OPERAND (x, 0)))
3318 error ("GIMPLE register modified with BIT_FIELD_REF");
3324 /* ??? tree-ssa-alias.c may have overlooked dead PHI nodes, missing
3325 dead PHIs that take the address of something. But if the PHI
3326 result is dead, the fact that it takes the address of anything
3327 is irrelevant. Because we can not tell from here if a PHI result
3328 is dead, we just skip this check for PHIs altogether. This means
3329 we may be missing "valid" checks, but what can you do?
3330 This was PR19217. */
3334 /* Skip any references (they will be checked when we recurse down the
3335 tree) and ensure that any variable used as a prefix is marked
3337 for (x = TREE_OPERAND (t, 0);
3338 handled_component_p (x);
3339 x = TREE_OPERAND (x, 0))
3342 if (TREE_CODE (x) != VAR_DECL && TREE_CODE (x) != PARM_DECL)
3344 if (!TREE_ADDRESSABLE (x))
3346 error ("address taken, but ADDRESSABLE bit not set");
3352 x = COND_EXPR_COND (t);
3353 if (TREE_CODE (TREE_TYPE (x)) != BOOLEAN_TYPE)
3355 error ("non-boolean used in condition");
3362 case FIX_TRUNC_EXPR:
3364 case FIX_FLOOR_EXPR:
3365 case FIX_ROUND_EXPR:
3370 case NON_LVALUE_EXPR:
3371 case TRUTH_NOT_EXPR:
3372 CHECK_OP (0, "Invalid operand to unary operator");
3379 case ARRAY_RANGE_REF:
3381 case VIEW_CONVERT_EXPR:
3382 /* We have a nest of references. Verify that each of the operands
3383 that determine where to reference is either a constant or a variable,
3384 verify that the base is valid, and then show we've already checked
3386 while (handled_component_p (t))
3388 if (TREE_CODE (t) == COMPONENT_REF && TREE_OPERAND (t, 2))
3389 CHECK_OP (2, "Invalid COMPONENT_REF offset operator");
3390 else if (TREE_CODE (t) == ARRAY_REF
3391 || TREE_CODE (t) == ARRAY_RANGE_REF)
3393 CHECK_OP (1, "Invalid array index.");
3394 if (TREE_OPERAND (t, 2))
3395 CHECK_OP (2, "Invalid array lower bound.");
3396 if (TREE_OPERAND (t, 3))
3397 CHECK_OP (3, "Invalid array stride.");
3399 else if (TREE_CODE (t) == BIT_FIELD_REF)
3401 CHECK_OP (1, "Invalid operand to BIT_FIELD_REF");
3402 CHECK_OP (2, "Invalid operand to BIT_FIELD_REF");
3405 t = TREE_OPERAND (t, 0);
3408 if (!CONSTANT_CLASS_P (t) && !is_gimple_lvalue (t))
3410 error ("Invalid reference prefix.");
3422 case UNORDERED_EXPR:
3433 case TRUNC_DIV_EXPR:
3435 case FLOOR_DIV_EXPR:
3436 case ROUND_DIV_EXPR:
3437 case TRUNC_MOD_EXPR:
3439 case FLOOR_MOD_EXPR:
3440 case ROUND_MOD_EXPR:
3442 case EXACT_DIV_EXPR:
3452 CHECK_OP (0, "Invalid operand to binary operator");
3453 CHECK_OP (1, "Invalid operand to binary operator");
3465 /* Verify STMT, return true if STMT is not in GIMPLE form.
3466 TODO: Implement type checking. */
3469 verify_stmt (tree stmt, bool last_in_block)
3473 if (!is_gimple_stmt (stmt))
3475 error ("Is not a valid GIMPLE statement.");
3479 addr = walk_tree (&stmt, verify_expr, NULL, NULL);
3482 debug_generic_stmt (addr);
3486 /* If the statement is marked as part of an EH region, then it is
3487 expected that the statement could throw. Verify that when we
3488 have optimizations that simplify statements such that we prove
3489 that they cannot throw, that we update other data structures
3491 if (lookup_stmt_eh_region (stmt) >= 0)
3493 if (!tree_could_throw_p (stmt))
3495 error ("Statement marked for throw, but doesn%'t.");
3498 if (!last_in_block && tree_can_throw_internal (stmt))
3500 error ("Statement marked for throw in middle of block.");
3508 debug_generic_stmt (stmt);
3513 /* Return true when the T can be shared. */
3516 tree_node_can_be_shared (tree t)
3518 if (IS_TYPE_OR_DECL_P (t)
3519 /* We check for constants explicitly since they are not considered
3520 gimple invariants if they overflowed. */
3521 || CONSTANT_CLASS_P (t)
3522 || is_gimple_min_invariant (t)
3523 || TREE_CODE (t) == SSA_NAME
3524 || t == error_mark_node)
3527 if (TREE_CODE (t) == CASE_LABEL_EXPR)
3530 while (((TREE_CODE (t) == ARRAY_REF || TREE_CODE (t) == ARRAY_RANGE_REF)
3531 /* We check for constants explicitly since they are not considered
3532 gimple invariants if they overflowed. */
3533 && (CONSTANT_CLASS_P (TREE_OPERAND (t, 1))
3534 || is_gimple_min_invariant (TREE_OPERAND (t, 1))))
3535 || (TREE_CODE (t) == COMPONENT_REF
3536 || TREE_CODE (t) == REALPART_EXPR
3537 || TREE_CODE (t) == IMAGPART_EXPR))
3538 t = TREE_OPERAND (t, 0);
3547 /* Called via walk_trees. Verify tree sharing. */
3550 verify_node_sharing (tree * tp, int *walk_subtrees, void *data)
3552 htab_t htab = (htab_t) data;
3555 if (tree_node_can_be_shared (*tp))
3557 *walk_subtrees = false;
3561 slot = htab_find_slot (htab, *tp, INSERT);
3570 /* Verify the GIMPLE statement chain. */
3576 block_stmt_iterator bsi;
3581 timevar_push (TV_TREE_STMT_VERIFY);
3582 htab = htab_create (37, htab_hash_pointer, htab_eq_pointer, NULL);
3589 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
3591 int phi_num_args = PHI_NUM_ARGS (phi);
3593 if (bb_for_stmt (phi) != bb)
3595 error ("bb_for_stmt (phi) is set to a wrong basic block\n");
3599 for (i = 0; i < phi_num_args; i++)
3601 tree t = PHI_ARG_DEF (phi, i);
3604 /* Addressable variables do have SSA_NAMEs but they
3605 are not considered gimple values. */
3606 if (TREE_CODE (t) != SSA_NAME
3607 && TREE_CODE (t) != FUNCTION_DECL
3608 && !is_gimple_val (t))
3610 error ("PHI def is not a GIMPLE value");
3611 debug_generic_stmt (phi);
3612 debug_generic_stmt (t);
3616 addr = walk_tree (&t, verify_expr, (void *) 1, NULL);
3619 debug_generic_stmt (addr);
3623 addr = walk_tree (&t, verify_node_sharing, htab, NULL);
3626 error ("Incorrect sharing of tree nodes");
3627 debug_generic_stmt (phi);
3628 debug_generic_stmt (addr);
3634 for (bsi = bsi_start (bb); !bsi_end_p (bsi); )
3636 tree stmt = bsi_stmt (bsi);
3638 if (bb_for_stmt (stmt) != bb)
3640 error ("bb_for_stmt (stmt) is set to a wrong basic block\n");
3645 err |= verify_stmt (stmt, bsi_end_p (bsi));
3646 addr = walk_tree (&stmt, verify_node_sharing, htab, NULL);
3649 error ("Incorrect sharing of tree nodes");
3650 debug_generic_stmt (stmt);
3651 debug_generic_stmt (addr);
3658 internal_error ("verify_stmts failed.");
3661 timevar_pop (TV_TREE_STMT_VERIFY);
3665 /* Verifies that the flow information is OK. */
3668 tree_verify_flow_info (void)
3672 block_stmt_iterator bsi;
3677 if (ENTRY_BLOCK_PTR->stmt_list)
3679 error ("ENTRY_BLOCK has a statement list associated with it\n");
3683 if (EXIT_BLOCK_PTR->stmt_list)
3685 error ("EXIT_BLOCK has a statement list associated with it\n");
3689 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
3690 if (e->flags & EDGE_FALLTHRU)
3692 error ("Fallthru to exit from bb %d\n", e->src->index);
3698 bool found_ctrl_stmt = false;
3702 /* Skip labels on the start of basic block. */
3703 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3705 tree prev_stmt = stmt;
3707 stmt = bsi_stmt (bsi);
3709 if (TREE_CODE (stmt) != LABEL_EXPR)
3712 if (prev_stmt && DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)))
3714 error ("Nonlocal label %s is not first "
3715 "in a sequence of labels in bb %d",
3716 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt))),
3721 if (label_to_block (LABEL_EXPR_LABEL (stmt)) != bb)
3723 error ("Label %s to block does not match in bb %d\n",
3724 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt))),
3729 if (decl_function_context (LABEL_EXPR_LABEL (stmt))
3730 != current_function_decl)
3732 error ("Label %s has incorrect context in bb %d\n",
3733 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt))),
3739 /* Verify that body of basic block BB is free of control flow. */
3740 for (; !bsi_end_p (bsi); bsi_next (&bsi))
3742 tree stmt = bsi_stmt (bsi);
3744 if (found_ctrl_stmt)
3746 error ("Control flow in the middle of basic block %d\n",
3751 if (stmt_ends_bb_p (stmt))
3752 found_ctrl_stmt = true;
3754 if (TREE_CODE (stmt) == LABEL_EXPR)
3756 error ("Label %s in the middle of basic block %d\n",
3757 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt))),
3762 bsi = bsi_last (bb);
3763 if (bsi_end_p (bsi))
3766 stmt = bsi_stmt (bsi);
3768 err |= verify_eh_edges (stmt);
3770 if (is_ctrl_stmt (stmt))
3772 FOR_EACH_EDGE (e, ei, bb->succs)
3773 if (e->flags & EDGE_FALLTHRU)
3775 error ("Fallthru edge after a control statement in bb %d \n",
3781 switch (TREE_CODE (stmt))
3787 if (TREE_CODE (COND_EXPR_THEN (stmt)) != GOTO_EXPR
3788 || TREE_CODE (COND_EXPR_ELSE (stmt)) != GOTO_EXPR)
3790 error ("Structured COND_EXPR at the end of bb %d\n", bb->index);
3794 extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
3796 if (!true_edge || !false_edge
3797 || !(true_edge->flags & EDGE_TRUE_VALUE)
3798 || !(false_edge->flags & EDGE_FALSE_VALUE)
3799 || (true_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL))
3800 || (false_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL))
3801 || EDGE_COUNT (bb->succs) >= 3)
3803 error ("Wrong outgoing edge flags at end of bb %d\n",
3808 if (!has_label_p (true_edge->dest,
3809 GOTO_DESTINATION (COND_EXPR_THEN (stmt))))
3811 error ("%<then%> label does not match edge at end of bb %d\n",
3816 if (!has_label_p (false_edge->dest,
3817 GOTO_DESTINATION (COND_EXPR_ELSE (stmt))))
3819 error ("%<else%> label does not match edge at end of bb %d\n",
3827 if (simple_goto_p (stmt))
3829 error ("Explicit goto at end of bb %d\n", bb->index);
3834 /* FIXME. We should double check that the labels in the
3835 destination blocks have their address taken. */
3836 FOR_EACH_EDGE (e, ei, bb->succs)
3837 if ((e->flags & (EDGE_FALLTHRU | EDGE_TRUE_VALUE
3838 | EDGE_FALSE_VALUE))
3839 || !(e->flags & EDGE_ABNORMAL))
3841 error ("Wrong outgoing edge flags at end of bb %d\n",
3849 if (!single_succ_p (bb)
3850 || (single_succ_edge (bb)->flags
3851 & (EDGE_FALLTHRU | EDGE_ABNORMAL
3852 | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
3854 error ("Wrong outgoing edge flags at end of bb %d\n", bb->index);
3857 if (single_succ (bb) != EXIT_BLOCK_PTR)
3859 error ("Return edge does not point to exit in bb %d\n",
3872 vec = SWITCH_LABELS (stmt);
3873 n = TREE_VEC_LENGTH (vec);
3875 /* Mark all the destination basic blocks. */
3876 for (i = 0; i < n; ++i)
3878 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
3879 basic_block label_bb = label_to_block (lab);
3881 gcc_assert (!label_bb->aux || label_bb->aux == (void *)1);
3882 label_bb->aux = (void *)1;
3885 /* Verify that the case labels are sorted. */
3886 prev = TREE_VEC_ELT (vec, 0);
3887 for (i = 1; i < n - 1; ++i)
3889 tree c = TREE_VEC_ELT (vec, i);
3892 error ("Found default case not at end of case vector");
3896 if (! tree_int_cst_lt (CASE_LOW (prev), CASE_LOW (c)))
3898 error ("Case labels not sorted:\n ");
3899 print_generic_expr (stderr, prev, 0);
3900 fprintf (stderr," is greater than ");
3901 print_generic_expr (stderr, c, 0);
3902 fprintf (stderr," but comes before it.\n");
3907 if (CASE_LOW (TREE_VEC_ELT (vec, n - 1)))
3909 error ("No default case found at end of case vector");
3913 FOR_EACH_EDGE (e, ei, bb->succs)
3917 error ("Extra outgoing edge %d->%d\n",
3918 bb->index, e->dest->index);
3921 e->dest->aux = (void *)2;
3922 if ((e->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL
3923 | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
3925 error ("Wrong outgoing edge flags at end of bb %d\n",
3931 /* Check that we have all of them. */
3932 for (i = 0; i < n; ++i)
3934 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
3935 basic_block label_bb = label_to_block (lab);
3937 if (label_bb->aux != (void *)2)
3939 error ("Missing edge %i->%i",
3940 bb->index, label_bb->index);
3945 FOR_EACH_EDGE (e, ei, bb->succs)
3946 e->dest->aux = (void *)0;
3953 if (dom_computed[CDI_DOMINATORS] >= DOM_NO_FAST_QUERY)
3954 verify_dominators (CDI_DOMINATORS);
3960 /* Updates phi nodes after creating a forwarder block joined
3961 by edge FALLTHRU. */
3964 tree_make_forwarder_block (edge fallthru)
3968 basic_block dummy, bb;
3969 tree phi, new_phi, var;
3971 dummy = fallthru->src;
3972 bb = fallthru->dest;
3974 if (single_pred_p (bb))
3977 /* If we redirected a branch we must create new phi nodes at the
3979 for (phi = phi_nodes (dummy); phi; phi = PHI_CHAIN (phi))
3981 var = PHI_RESULT (phi);
3982 new_phi = create_phi_node (var, bb);
3983 SSA_NAME_DEF_STMT (var) = new_phi;
3984 SET_PHI_RESULT (phi, make_ssa_name (SSA_NAME_VAR (var), phi));
3985 add_phi_arg (new_phi, PHI_RESULT (phi), fallthru);
3988 /* Ensure that the PHI node chain is in the same order. */
3989 set_phi_nodes (bb, phi_reverse (phi_nodes (bb)));
3991 /* Add the arguments we have stored on edges. */
3992 FOR_EACH_EDGE (e, ei, bb->preds)
3997 flush_pending_stmts (e);
4002 /* Return true if basic block BB does nothing except pass control
4003 flow to another block and that we can safely insert a label at
4004 the start of the successor block.
4006 As a precondition, we require that BB be not equal to
4010 tree_forwarder_block_p (basic_block bb, bool phi_wanted)
4012 block_stmt_iterator bsi;
4014 /* BB must have a single outgoing edge. */
4015 if (single_succ_p (bb) != 1
4016 /* If PHI_WANTED is false, BB must not have any PHI nodes.
4017 Otherwise, BB must have PHI nodes. */
4018 || (phi_nodes (bb) != NULL_TREE) != phi_wanted
4019 /* BB may not be a predecessor of EXIT_BLOCK_PTR. */
4020 || single_succ (bb) == EXIT_BLOCK_PTR
4021 /* Nor should this be an infinite loop. */
4022 || single_succ (bb) == bb
4023 /* BB may not have an abnormal outgoing edge. */
4024 || (single_succ_edge (bb)->flags & EDGE_ABNORMAL))
4028 gcc_assert (bb != ENTRY_BLOCK_PTR);
4031 /* Now walk through the statements backward. We can ignore labels,
4032 anything else means this is not a forwarder block. */
4033 for (bsi = bsi_last (bb); !bsi_end_p (bsi); bsi_prev (&bsi))
4035 tree stmt = bsi_stmt (bsi);
4037 switch (TREE_CODE (stmt))
4040 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)))
4049 if (find_edge (ENTRY_BLOCK_PTR, bb))
4055 /* Protect loop latches, headers and preheaders. */
4056 if (bb->loop_father->header == bb)
4058 dest = EDGE_SUCC (bb, 0)->dest;
4060 if (dest->loop_father->header == dest)
4067 /* Return true if BB has at least one abnormal incoming edge. */
4070 has_abnormal_incoming_edge_p (basic_block bb)
4075 FOR_EACH_EDGE (e, ei, bb->preds)
4076 if (e->flags & EDGE_ABNORMAL)
4082 /* Removes forwarder block BB. Returns false if this failed. If a new
4083 forwarder block is created due to redirection of edges, it is
4084 stored to worklist. */
4087 remove_forwarder_block (basic_block bb, basic_block **worklist)
4089 edge succ = single_succ_edge (bb), e, s;
4090 basic_block dest = succ->dest;
4094 block_stmt_iterator bsi, bsi_to;
4095 bool seen_abnormal_edge = false;
4097 /* We check for infinite loops already in tree_forwarder_block_p.
4098 However it may happen that the infinite loop is created
4099 afterwards due to removal of forwarders. */
4103 /* If the destination block consists of a nonlocal label, do not merge
4105 label = first_stmt (dest);
4107 && TREE_CODE (label) == LABEL_EXPR
4108 && DECL_NONLOCAL (LABEL_EXPR_LABEL (label)))
4111 /* If there is an abnormal edge to basic block BB, but not into
4112 dest, problems might occur during removal of the phi node at out
4113 of ssa due to overlapping live ranges of registers.
4115 If there is an abnormal edge in DEST, the problems would occur
4116 anyway since cleanup_dead_labels would then merge the labels for
4117 two different eh regions, and rest of exception handling code
4120 So if there is an abnormal edge to BB, proceed only if there is
4121 no abnormal edge to DEST and there are no phi nodes in DEST. */
4122 if (has_abnormal_incoming_edge_p (bb))
4124 seen_abnormal_edge = true;
4126 if (has_abnormal_incoming_edge_p (dest)
4127 || phi_nodes (dest) != NULL_TREE)
4131 /* If there are phi nodes in DEST, and some of the blocks that are
4132 predecessors of BB are also predecessors of DEST, check that the
4133 phi node arguments match. */
4134 if (phi_nodes (dest))
4136 FOR_EACH_EDGE (e, ei, bb->preds)
4138 s = find_edge (e->src, dest);
4142 if (!phi_alternatives_equal (dest, succ, s))
4147 /* Redirect the edges. */
4148 for (ei = ei_start (bb->preds); (e = ei_safe_edge (ei)); )
4150 if (e->flags & EDGE_ABNORMAL)
4152 /* If there is an abnormal edge, redirect it anyway, and
4153 move the labels to the new block to make it legal. */
4154 s = redirect_edge_succ_nodup (e, dest);
4157 s = redirect_edge_and_branch (e, dest);
4161 /* Create arguments for the phi nodes, since the edge was not
4163 for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi))
4164 add_phi_arg (phi, PHI_ARG_DEF (phi, succ->dest_idx), s);
4168 /* The source basic block might become a forwarder. We know
4169 that it was not a forwarder before, since it used to have
4170 at least two outgoing edges, so we may just add it to
4172 if (tree_forwarder_block_p (s->src, false))
4173 *(*worklist)++ = s->src;
4177 if (seen_abnormal_edge)
4179 /* Move the labels to the new block, so that the redirection of
4180 the abnormal edges works. */
4182 bsi_to = bsi_start (dest);
4183 for (bsi = bsi_start (bb); !bsi_end_p (bsi); )
4185 label = bsi_stmt (bsi);
4186 gcc_assert (TREE_CODE (label) == LABEL_EXPR);
4188 bsi_insert_before (&bsi_to, label, BSI_CONTINUE_LINKING);
4192 /* Update the dominators. */
4193 if (dom_info_available_p (CDI_DOMINATORS))
4195 basic_block dom, dombb, domdest;
4197 dombb = get_immediate_dominator (CDI_DOMINATORS, bb);
4198 domdest = get_immediate_dominator (CDI_DOMINATORS, dest);
4201 /* Shortcut to avoid calling (relatively expensive)
4202 nearest_common_dominator unless necessary. */
4206 dom = nearest_common_dominator (CDI_DOMINATORS, domdest, dombb);
4208 set_immediate_dominator (CDI_DOMINATORS, dest, dom);
4211 /* And kill the forwarder block. */
4212 delete_basic_block (bb);
4217 /* Removes forwarder blocks. */
4220 cleanup_forwarder_blocks (void)
4223 bool changed = false;
4224 basic_block *worklist = xmalloc (sizeof (basic_block) * n_basic_blocks);
4225 basic_block *current = worklist;
4229 if (tree_forwarder_block_p (bb, false))
4233 while (current != worklist)
4236 changed |= remove_forwarder_block (bb, ¤t);
4243 /* Merge the PHI nodes at BB into those at BB's sole successor. */
4246 remove_forwarder_block_with_phi (basic_block bb)
4248 edge succ = single_succ_edge (bb);
4249 basic_block dest = succ->dest;
4251 basic_block dombb, domdest, dom;
4253 /* We check for infinite loops already in tree_forwarder_block_p.
4254 However it may happen that the infinite loop is created
4255 afterwards due to removal of forwarders. */
4259 /* If the destination block consists of a nonlocal label, do not
4261 label = first_stmt (dest);
4263 && TREE_CODE (label) == LABEL_EXPR
4264 && DECL_NONLOCAL (LABEL_EXPR_LABEL (label)))
4267 /* Redirect each incoming edge to BB to DEST. */
4268 while (EDGE_COUNT (bb->preds) > 0)
4270 edge e = EDGE_PRED (bb, 0), s;
4273 s = find_edge (e->src, dest);
4276 /* We already have an edge S from E->src to DEST. If S and
4277 E->dest's sole successor edge have the same PHI arguments
4278 at DEST, redirect S to DEST. */
4279 if (phi_alternatives_equal (dest, s, succ))
4281 e = redirect_edge_and_branch (e, dest);
4282 PENDING_STMT (e) = NULL_TREE;
4286 /* PHI arguments are different. Create a forwarder block by
4287 splitting E so that we can merge PHI arguments on E to
4289 e = single_succ_edge (split_edge (e));
4292 s = redirect_edge_and_branch (e, dest);
4294 /* redirect_edge_and_branch must not create a new edge. */
4295 gcc_assert (s == e);
4297 /* Add to the PHI nodes at DEST each PHI argument removed at the
4298 destination of E. */
4299 for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi))
4301 tree def = PHI_ARG_DEF (phi, succ->dest_idx);
4303 if (TREE_CODE (def) == SSA_NAME)
4307 /* If DEF is one of the results of PHI nodes removed during
4308 redirection, replace it with the PHI argument that used
4310 for (var = PENDING_STMT (e); var; var = TREE_CHAIN (var))
4312 tree old_arg = TREE_PURPOSE (var);
4313 tree new_arg = TREE_VALUE (var);
4323 add_phi_arg (phi, def, s);
4326 PENDING_STMT (e) = NULL;
4329 /* Update the dominators. */
4330 dombb = get_immediate_dominator (CDI_DOMINATORS, bb);
4331 domdest = get_immediate_dominator (CDI_DOMINATORS, dest);
4334 /* Shortcut to avoid calling (relatively expensive)
4335 nearest_common_dominator unless necessary. */
4339 dom = nearest_common_dominator (CDI_DOMINATORS, domdest, dombb);
4341 set_immediate_dominator (CDI_DOMINATORS, dest, dom);
4343 /* Remove BB since all of BB's incoming edges have been redirected
4345 delete_basic_block (bb);
4348 /* This pass merges PHI nodes if one feeds into another. For example,
4349 suppose we have the following:
4356 # tem_6 = PHI <tem_17(8), tem_23(7)>;
4359 # tem_3 = PHI <tem_6(9), tem_2(5)>;
4362 Then we merge the first PHI node into the second one like so:
4364 goto <bb 9> (<L10>);
4369 # tem_3 = PHI <tem_23(7), tem_2(5), tem_17(8)>;
4374 merge_phi_nodes (void)
4376 basic_block *worklist = xmalloc (sizeof (basic_block) * n_basic_blocks);
4377 basic_block *current = worklist;
4380 calculate_dominance_info (CDI_DOMINATORS);
4382 /* Find all PHI nodes that we may be able to merge. */
4387 /* Look for a forwarder block with PHI nodes. */
4388 if (!tree_forwarder_block_p (bb, true))
4391 dest = single_succ (bb);
4393 /* We have to feed into another basic block with PHI
4395 if (!phi_nodes (dest)
4396 /* We don't want to deal with a basic block with
4398 || has_abnormal_incoming_edge_p (bb))
4401 if (!dominated_by_p (CDI_DOMINATORS, dest, bb))
4403 /* If BB does not dominate DEST, then the PHI nodes at
4404 DEST must be the only users of the results of the PHI
4410 /* Now let's drain WORKLIST. */
4411 while (current != worklist)
4414 remove_forwarder_block_with_phi (bb);
4421 gate_merge_phi (void)
4426 struct tree_opt_pass pass_merge_phi = {
4427 "mergephi", /* name */
4428 gate_merge_phi, /* gate */
4429 merge_phi_nodes, /* execute */
4432 0, /* static_pass_number */
4433 TV_TREE_MERGE_PHI, /* tv_id */
4434 PROP_cfg | PROP_ssa, /* properties_required */
4435 0, /* properties_provided */
4436 0, /* properties_destroyed */
4437 0, /* todo_flags_start */
4438 TODO_dump_func | TODO_ggc_collect /* todo_flags_finish */
4443 /* Return a non-special label in the head of basic block BLOCK.
4444 Create one if it doesn't exist. */
4447 tree_block_label (basic_block bb)
4449 block_stmt_iterator i, s = bsi_start (bb);
4453 for (i = s; !bsi_end_p (i); first = false, bsi_next (&i))
4455 stmt = bsi_stmt (i);
4456 if (TREE_CODE (stmt) != LABEL_EXPR)
4458 label = LABEL_EXPR_LABEL (stmt);
4459 if (!DECL_NONLOCAL (label))
4462 bsi_move_before (&i, &s);
4467 label = create_artificial_label ();
4468 stmt = build1 (LABEL_EXPR, void_type_node, label);
4469 bsi_insert_before (&s, stmt, BSI_NEW_STMT);
4474 /* Attempt to perform edge redirection by replacing a possibly complex
4475 jump instruction by a goto or by removing the jump completely.
4476 This can apply only if all edges now point to the same block. The
4477 parameters and return values are equivalent to
4478 redirect_edge_and_branch. */
4481 tree_try_redirect_by_replacing_jump (edge e, basic_block target)
4483 basic_block src = e->src;
4484 block_stmt_iterator b;
4487 /* We can replace or remove a complex jump only when we have exactly
4489 if (EDGE_COUNT (src->succs) != 2
4490 /* Verify that all targets will be TARGET. Specifically, the
4491 edge that is not E must also go to TARGET. */
4492 || EDGE_SUCC (src, EDGE_SUCC (src, 0) == e)->dest != target)
4498 stmt = bsi_stmt (b);
4500 if (TREE_CODE (stmt) == COND_EXPR
4501 || TREE_CODE (stmt) == SWITCH_EXPR)
4504 e = ssa_redirect_edge (e, target);
4505 e->flags = EDGE_FALLTHRU;
4513 /* Redirect E to DEST. Return NULL on failure. Otherwise, return the
4514 edge representing the redirected branch. */
4517 tree_redirect_edge_and_branch (edge e, basic_block dest)
4519 basic_block bb = e->src;
4520 block_stmt_iterator bsi;
4524 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
4527 if (e->src != ENTRY_BLOCK_PTR
4528 && (ret = tree_try_redirect_by_replacing_jump (e, dest)))
4531 if (e->dest == dest)
4534 label = tree_block_label (dest);
4536 bsi = bsi_last (bb);
4537 stmt = bsi_end_p (bsi) ? NULL : bsi_stmt (bsi);
4539 switch (stmt ? TREE_CODE (stmt) : ERROR_MARK)
4542 stmt = (e->flags & EDGE_TRUE_VALUE
4543 ? COND_EXPR_THEN (stmt)
4544 : COND_EXPR_ELSE (stmt));
4545 GOTO_DESTINATION (stmt) = label;
4549 /* No non-abnormal edges should lead from a non-simple goto, and
4550 simple ones should be represented implicitly. */
4555 tree cases = get_cases_for_edge (e, stmt);
4557 /* If we have a list of cases associated with E, then use it
4558 as it's a lot faster than walking the entire case vector. */
4561 edge e2 = find_edge (e->src, dest);
4568 CASE_LABEL (cases) = label;
4569 cases = TREE_CHAIN (cases);
4572 /* If there was already an edge in the CFG, then we need
4573 to move all the cases associated with E to E2. */
4576 tree cases2 = get_cases_for_edge (e2, stmt);
4578 TREE_CHAIN (last) = TREE_CHAIN (cases2);
4579 TREE_CHAIN (cases2) = first;
4584 tree vec = SWITCH_LABELS (stmt);
4585 size_t i, n = TREE_VEC_LENGTH (vec);
4587 for (i = 0; i < n; i++)
4589 tree elt = TREE_VEC_ELT (vec, i);
4591 if (label_to_block (CASE_LABEL (elt)) == e->dest)
4592 CASE_LABEL (elt) = label;
4601 e->flags |= EDGE_FALLTHRU;
4605 /* Otherwise it must be a fallthru edge, and we don't need to
4606 do anything besides redirecting it. */
4607 gcc_assert (e->flags & EDGE_FALLTHRU);
4611 /* Update/insert PHI nodes as necessary. */
4613 /* Now update the edges in the CFG. */
4614 e = ssa_redirect_edge (e, dest);
4620 /* Simple wrapper, as we can always redirect fallthru edges. */
4623 tree_redirect_edge_and_branch_force (edge e, basic_block dest)
4625 e = tree_redirect_edge_and_branch (e, dest);
4632 /* Splits basic block BB after statement STMT (but at least after the
4633 labels). If STMT is NULL, BB is split just after the labels. */
4636 tree_split_block (basic_block bb, void *stmt)
4638 block_stmt_iterator bsi, bsi_tgt;
4644 new_bb = create_empty_bb (bb);
4646 /* Redirect the outgoing edges. */
4647 new_bb->succs = bb->succs;
4649 FOR_EACH_EDGE (e, ei, new_bb->succs)
4652 if (stmt && TREE_CODE ((tree) stmt) == LABEL_EXPR)
4655 /* Move everything from BSI to the new basic block. */
4656 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4658 act = bsi_stmt (bsi);
4659 if (TREE_CODE (act) == LABEL_EXPR)
4672 bsi_tgt = bsi_start (new_bb);
4673 while (!bsi_end_p (bsi))
4675 act = bsi_stmt (bsi);
4677 bsi_insert_after (&bsi_tgt, act, BSI_NEW_STMT);
4684 /* Moves basic block BB after block AFTER. */
4687 tree_move_block_after (basic_block bb, basic_block after)
4689 if (bb->prev_bb == after)
4693 link_block (bb, after);
4699 /* Return true if basic_block can be duplicated. */
4702 tree_can_duplicate_bb_p (basic_block bb ATTRIBUTE_UNUSED)
4708 /* Create a duplicate of the basic block BB. NOTE: This does not
4709 preserve SSA form. */
4712 tree_duplicate_bb (basic_block bb)
4715 block_stmt_iterator bsi, bsi_tgt;
4718 new_bb = create_empty_bb (EXIT_BLOCK_PTR->prev_bb);
4720 /* Copy the PHI nodes. We ignore PHI node arguments here because
4721 the incoming edges have not been setup yet. */
4722 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
4724 tree copy = create_phi_node (PHI_RESULT (phi), new_bb);
4725 create_new_def_for (PHI_RESULT (copy), copy, PHI_RESULT_PTR (copy));
4728 /* Keep the chain of PHI nodes in the same order so that they can be
4729 updated by ssa_redirect_edge. */
4730 set_phi_nodes (new_bb, phi_reverse (phi_nodes (new_bb)));
4732 bsi_tgt = bsi_start (new_bb);
4733 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4735 def_operand_p def_p;
4736 ssa_op_iter op_iter;
4740 stmt = bsi_stmt (bsi);
4741 if (TREE_CODE (stmt) == LABEL_EXPR)
4744 /* Create a new copy of STMT and duplicate STMT's virtual
4746 copy = unshare_expr (stmt);
4747 bsi_insert_after (&bsi_tgt, copy, BSI_NEW_STMT);
4748 copy_virtual_operands (copy, stmt);
4749 region = lookup_stmt_eh_region (stmt);
4751 add_stmt_to_eh_region (copy, region);
4753 /* Create new names for all the definitions created by COPY and
4754 add replacement mappings for each new name. */
4755 FOR_EACH_SSA_DEF_OPERAND (def_p, copy, op_iter, SSA_OP_ALL_DEFS)
4756 create_new_def_for (DEF_FROM_PTR (def_p), copy, def_p);
4763 /* Basic block BB_COPY was created by code duplication. Add phi node
4764 arguments for edges going out of BB_COPY. The blocks that were
4765 duplicated have rbi->duplicated set to one. */
4768 add_phi_args_after_copy_bb (basic_block bb_copy)
4770 basic_block bb, dest;
4773 tree phi, phi_copy, phi_next, def;
4775 bb = bb_copy->rbi->original;
4777 FOR_EACH_EDGE (e_copy, ei, bb_copy->succs)
4779 if (!phi_nodes (e_copy->dest))
4782 if (e_copy->dest->rbi->duplicated)
4783 dest = e_copy->dest->rbi->original;
4785 dest = e_copy->dest;
4787 e = find_edge (bb, dest);
4790 /* During loop unrolling the target of the latch edge is copied.
4791 In this case we are not looking for edge to dest, but to
4792 duplicated block whose original was dest. */
4793 FOR_EACH_EDGE (e, ei, bb->succs)
4794 if (e->dest->rbi->duplicated
4795 && e->dest->rbi->original == dest)
4798 gcc_assert (e != NULL);
4801 for (phi = phi_nodes (e->dest), phi_copy = phi_nodes (e_copy->dest);
4803 phi = phi_next, phi_copy = PHI_CHAIN (phi_copy))
4805 phi_next = PHI_CHAIN (phi);
4806 def = PHI_ARG_DEF_FROM_EDGE (phi, e);
4807 add_phi_arg (phi_copy, def, e_copy);
4812 /* Blocks in REGION_COPY array of length N_REGION were created by
4813 duplication of basic blocks. Add phi node arguments for edges
4814 going from these blocks. */
4817 add_phi_args_after_copy (basic_block *region_copy, unsigned n_region)
4821 for (i = 0; i < n_region; i++)
4822 region_copy[i]->rbi->duplicated = 1;
4824 for (i = 0; i < n_region; i++)
4825 add_phi_args_after_copy_bb (region_copy[i]);
4827 for (i = 0; i < n_region; i++)
4828 region_copy[i]->rbi->duplicated = 0;
4831 /* Duplicates a REGION (set of N_REGION basic blocks) with just a single
4832 important exit edge EXIT. By important we mean that no SSA name defined
4833 inside region is live over the other exit edges of the region. All entry
4834 edges to the region must go to ENTRY->dest. The edge ENTRY is redirected
4835 to the duplicate of the region. SSA form, dominance and loop information
4836 is updated. The new basic blocks are stored to REGION_COPY in the same
4837 order as they had in REGION, provided that REGION_COPY is not NULL.
4838 The function returns false if it is unable to copy the region,
4842 tree_duplicate_sese_region (edge entry, edge exit,
4843 basic_block *region, unsigned n_region,
4844 basic_block *region_copy)
4847 bool free_region_copy = false, copying_header = false;
4848 struct loop *loop = entry->dest->loop_father;
4852 int total_freq, entry_freq;
4854 if (!can_copy_bbs_p (region, n_region))
4857 /* Some sanity checking. Note that we do not check for all possible
4858 missuses of the functions. I.e. if you ask to copy something weird,
4859 it will work, but the state of structures probably will not be
4861 for (i = 0; i < n_region; i++)
4863 /* We do not handle subloops, i.e. all the blocks must belong to the
4865 if (region[i]->loop_father != loop)
4868 if (region[i] != entry->dest
4869 && region[i] == loop->header)
4875 /* In case the function is used for loop header copying (which is the primary
4876 use), ensure that EXIT and its copy will be new latch and entry edges. */
4877 if (loop->header == entry->dest)
4879 copying_header = true;
4880 loop->copy = loop->outer;
4882 if (!dominated_by_p (CDI_DOMINATORS, loop->latch, exit->src))
4885 for (i = 0; i < n_region; i++)
4886 if (region[i] != exit->src
4887 && dominated_by_p (CDI_DOMINATORS, region[i], exit->src))
4893 region_copy = xmalloc (sizeof (basic_block) * n_region);
4894 free_region_copy = true;
4897 gcc_assert (!need_ssa_update_p ());
4899 /* Record blocks outside the region that are dominated by something
4901 doms = xmalloc (sizeof (basic_block) * n_basic_blocks);
4902 n_doms = get_dominated_by_region (CDI_DOMINATORS, region, n_region, doms);
4904 total_freq = entry->dest->frequency;
4905 entry_freq = EDGE_FREQUENCY (entry);
4906 /* Fix up corner cases, to avoid division by zero or creation of negative
4908 if (total_freq == 0)
4910 else if (entry_freq > total_freq)
4911 entry_freq = total_freq;
4913 copy_bbs (region, n_region, region_copy, &exit, 1, &exit_copy, loop);
4914 scale_bbs_frequencies_int (region, n_region, total_freq - entry_freq,
4916 scale_bbs_frequencies_int (region_copy, n_region, entry_freq, total_freq);
4920 loop->header = exit->dest;
4921 loop->latch = exit->src;
4924 /* Redirect the entry and add the phi node arguments. */
4925 redirected = redirect_edge_and_branch (entry, entry->dest->rbi->copy);
4926 gcc_assert (redirected != NULL);
4927 flush_pending_stmts (entry);
4929 /* Concerning updating of dominators: We must recount dominators
4930 for entry block and its copy. Anything that is outside of the
4931 region, but was dominated by something inside needs recounting as
4933 set_immediate_dominator (CDI_DOMINATORS, entry->dest, entry->src);
4934 doms[n_doms++] = entry->dest->rbi->original;
4935 iterate_fix_dominators (CDI_DOMINATORS, doms, n_doms);
4938 /* Add the other PHI node arguments. */
4939 add_phi_args_after_copy (region_copy, n_region);
4941 /* Update the SSA web. */
4942 update_ssa (TODO_update_ssa);
4944 if (free_region_copy)
4951 /* Dump FUNCTION_DECL FN to file FILE using FLAGS (see TDF_* in tree.h) */
4954 dump_function_to_file (tree fn, FILE *file, int flags)
4956 tree arg, vars, var;
4957 bool ignore_topmost_bind = false, any_var = false;
4961 fprintf (file, "%s (", lang_hooks.decl_printable_name (fn, 2));
4963 arg = DECL_ARGUMENTS (fn);
4966 print_generic_expr (file, arg, dump_flags);
4967 if (TREE_CHAIN (arg))
4968 fprintf (file, ", ");
4969 arg = TREE_CHAIN (arg);
4971 fprintf (file, ")\n");
4973 if (flags & TDF_DETAILS)
4974 dump_eh_tree (file, DECL_STRUCT_FUNCTION (fn));
4975 if (flags & TDF_RAW)
4977 dump_node (fn, TDF_SLIM | flags, file);
4981 /* When GIMPLE is lowered, the variables are no longer available in
4982 BIND_EXPRs, so display them separately. */
4983 if (cfun && cfun->decl == fn && cfun->unexpanded_var_list)
4985 ignore_topmost_bind = true;
4987 fprintf (file, "{\n");
4988 for (vars = cfun->unexpanded_var_list; vars; vars = TREE_CHAIN (vars))
4990 var = TREE_VALUE (vars);
4992 print_generic_decl (file, var, flags);
4993 fprintf (file, "\n");
4999 if (cfun && cfun->decl == fn && cfun->cfg && basic_block_info)
5001 /* Make a CFG based dump. */
5002 check_bb_profile (ENTRY_BLOCK_PTR, file);
5003 if (!ignore_topmost_bind)
5004 fprintf (file, "{\n");
5006 if (any_var && n_basic_blocks)
5007 fprintf (file, "\n");
5010 dump_generic_bb (file, bb, 2, flags);
5012 fprintf (file, "}\n");
5013 check_bb_profile (EXIT_BLOCK_PTR, file);
5019 /* Make a tree based dump. */
5020 chain = DECL_SAVED_TREE (fn);
5022 if (TREE_CODE (chain) == BIND_EXPR)
5024 if (ignore_topmost_bind)
5026 chain = BIND_EXPR_BODY (chain);
5034 if (!ignore_topmost_bind)
5035 fprintf (file, "{\n");
5040 fprintf (file, "\n");
5042 print_generic_stmt_indented (file, chain, flags, indent);
5043 if (ignore_topmost_bind)
5044 fprintf (file, "}\n");
5047 fprintf (file, "\n\n");
5051 /* Pretty print of the loops intermediate representation. */
5052 static void print_loop (FILE *, struct loop *, int);
5053 static void print_pred_bbs (FILE *, basic_block bb);
5054 static void print_succ_bbs (FILE *, basic_block bb);
5057 /* Print the predecessors indexes of edge E on FILE. */
5060 print_pred_bbs (FILE *file, basic_block bb)
5065 FOR_EACH_EDGE (e, ei, bb->preds)
5066 fprintf (file, "bb_%d", e->src->index);
5070 /* Print the successors indexes of edge E on FILE. */
5073 print_succ_bbs (FILE *file, basic_block bb)
5078 FOR_EACH_EDGE (e, ei, bb->succs)
5079 fprintf (file, "bb_%d", e->src->index);
5083 /* Pretty print LOOP on FILE, indented INDENT spaces. */
5086 print_loop (FILE *file, struct loop *loop, int indent)
5094 s_indent = (char *) alloca ((size_t) indent + 1);
5095 memset ((void *) s_indent, ' ', (size_t) indent);
5096 s_indent[indent] = '\0';
5098 /* Print the loop's header. */
5099 fprintf (file, "%sloop_%d\n", s_indent, loop->num);
5101 /* Print the loop's body. */
5102 fprintf (file, "%s{\n", s_indent);
5104 if (bb->loop_father == loop)
5106 /* Print the basic_block's header. */
5107 fprintf (file, "%s bb_%d (preds = {", s_indent, bb->index);
5108 print_pred_bbs (file, bb);
5109 fprintf (file, "}, succs = {");
5110 print_succ_bbs (file, bb);
5111 fprintf (file, "})\n");
5113 /* Print the basic_block's body. */
5114 fprintf (file, "%s {\n", s_indent);
5115 tree_dump_bb (bb, file, indent + 4);
5116 fprintf (file, "%s }\n", s_indent);
5119 print_loop (file, loop->inner, indent + 2);
5120 fprintf (file, "%s}\n", s_indent);
5121 print_loop (file, loop->next, indent);
5125 /* Follow a CFG edge from the entry point of the program, and on entry
5126 of a loop, pretty print the loop structure on FILE. */
5129 print_loop_ir (FILE *file)
5133 bb = BASIC_BLOCK (0);
5134 if (bb && bb->loop_father)
5135 print_loop (file, bb->loop_father, 0);
5139 /* Debugging loops structure at tree level. */
5142 debug_loop_ir (void)
5144 print_loop_ir (stderr);
5148 /* Return true if BB ends with a call, possibly followed by some
5149 instructions that must stay with the call. Return false,
5153 tree_block_ends_with_call_p (basic_block bb)
5155 block_stmt_iterator bsi = bsi_last (bb);
5156 return get_call_expr_in (bsi_stmt (bsi)) != NULL;
5160 /* Return true if BB ends with a conditional branch. Return false,
5164 tree_block_ends_with_condjump_p (basic_block bb)
5166 tree stmt = last_stmt (bb);
5167 return (stmt && TREE_CODE (stmt) == COND_EXPR);
5171 /* Return true if we need to add fake edge to exit at statement T.
5172 Helper function for tree_flow_call_edges_add. */
5175 need_fake_edge_p (tree t)
5179 /* NORETURN and LONGJMP calls already have an edge to exit.
5180 CONST and PURE calls do not need one.
5181 We don't currently check for CONST and PURE here, although
5182 it would be a good idea, because those attributes are
5183 figured out from the RTL in mark_constant_function, and
5184 the counter incrementation code from -fprofile-arcs
5185 leads to different results from -fbranch-probabilities. */
5186 call = get_call_expr_in (t);
5188 && !(call_expr_flags (call) & ECF_NORETURN))
5191 if (TREE_CODE (t) == ASM_EXPR
5192 && (ASM_VOLATILE_P (t) || ASM_INPUT_P (t)))
5199 /* Add fake edges to the function exit for any non constant and non
5200 noreturn calls, volatile inline assembly in the bitmap of blocks
5201 specified by BLOCKS or to the whole CFG if BLOCKS is zero. Return
5202 the number of blocks that were split.
5204 The goal is to expose cases in which entering a basic block does
5205 not imply that all subsequent instructions must be executed. */
5208 tree_flow_call_edges_add (sbitmap blocks)
5211 int blocks_split = 0;
5212 int last_bb = last_basic_block;
5213 bool check_last_block = false;
5215 if (n_basic_blocks == 0)
5219 check_last_block = true;
5221 check_last_block = TEST_BIT (blocks, EXIT_BLOCK_PTR->prev_bb->index);
5223 /* In the last basic block, before epilogue generation, there will be
5224 a fallthru edge to EXIT. Special care is required if the last insn
5225 of the last basic block is a call because make_edge folds duplicate
5226 edges, which would result in the fallthru edge also being marked
5227 fake, which would result in the fallthru edge being removed by
5228 remove_fake_edges, which would result in an invalid CFG.
5230 Moreover, we can't elide the outgoing fake edge, since the block
5231 profiler needs to take this into account in order to solve the minimal
5232 spanning tree in the case that the call doesn't return.
5234 Handle this by adding a dummy instruction in a new last basic block. */
5235 if (check_last_block)
5237 basic_block bb = EXIT_BLOCK_PTR->prev_bb;
5238 block_stmt_iterator bsi = bsi_last (bb);
5240 if (!bsi_end_p (bsi))
5243 if (need_fake_edge_p (t))
5247 e = find_edge (bb, EXIT_BLOCK_PTR);
5250 bsi_insert_on_edge (e, build_empty_stmt ());
5251 bsi_commit_edge_inserts ();
5256 /* Now add fake edges to the function exit for any non constant
5257 calls since there is no way that we can determine if they will
5259 for (i = 0; i < last_bb; i++)
5261 basic_block bb = BASIC_BLOCK (i);
5262 block_stmt_iterator bsi;
5263 tree stmt, last_stmt;
5268 if (blocks && !TEST_BIT (blocks, i))
5271 bsi = bsi_last (bb);
5272 if (!bsi_end_p (bsi))
5274 last_stmt = bsi_stmt (bsi);
5277 stmt = bsi_stmt (bsi);
5278 if (need_fake_edge_p (stmt))
5281 /* The handling above of the final block before the
5282 epilogue should be enough to verify that there is
5283 no edge to the exit block in CFG already.
5284 Calling make_edge in such case would cause us to
5285 mark that edge as fake and remove it later. */
5286 #ifdef ENABLE_CHECKING
5287 if (stmt == last_stmt)
5289 e = find_edge (bb, EXIT_BLOCK_PTR);
5290 gcc_assert (e == NULL);
5294 /* Note that the following may create a new basic block
5295 and renumber the existing basic blocks. */
5296 if (stmt != last_stmt)
5298 e = split_block (bb, stmt);
5302 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
5306 while (!bsi_end_p (bsi));
5311 verify_flow_info ();
5313 return blocks_split;
5317 tree_purge_dead_eh_edges (basic_block bb)
5319 bool changed = false;
5322 tree stmt = last_stmt (bb);
5324 if (stmt && tree_can_throw_internal (stmt))
5327 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
5329 if (e->flags & EDGE_EH)
5338 /* Removal of dead EH edges might change dominators of not
5339 just immediate successors. E.g. when bb1 is changed so that
5340 it no longer can throw and bb1->bb3 and bb1->bb4 are dead
5341 eh edges purged by this function in:
5353 idom(bb5) must be recomputed. For now just free the dominance
5356 free_dominance_info (CDI_DOMINATORS);
5362 tree_purge_all_dead_eh_edges (bitmap blocks)
5364 bool changed = false;
5368 EXECUTE_IF_SET_IN_BITMAP (blocks, 0, i, bi)
5370 changed |= tree_purge_dead_eh_edges (BASIC_BLOCK (i));
5376 /* This function is called whenever a new edge is created or
5380 tree_execute_on_growing_pred (edge e)
5382 basic_block bb = e->dest;
5385 reserve_phi_args_for_new_edge (bb);
5388 /* This function is called immediately before edge E is removed from
5389 the edge vector E->dest->preds. */
5392 tree_execute_on_shrinking_pred (edge e)
5394 if (phi_nodes (e->dest))
5395 remove_phi_args (e);
5398 /*---------------------------------------------------------------------------
5399 Helper functions for Loop versioning
5400 ---------------------------------------------------------------------------*/
5402 /* Adjust phi nodes for 'first' basic block. 'second' basic block is a copy
5403 of 'first'. Both of them are dominated by 'new_head' basic block. When
5404 'new_head' was created by 'second's incoming edge it received phi arguments
5405 on the edge by split_edge(). Later, additional edge 'e' was created to
5406 connect 'new_head' and 'first'. Now this routine adds phi args on this
5407 additional edge 'e' that new_head to second edge received as part of edge
5412 tree_lv_adjust_loop_header_phi (basic_block first, basic_block second,
5413 basic_block new_head, edge e)
5416 edge e2 = find_edge (new_head, second);
5418 /* Because NEW_HEAD has been created by splitting SECOND's incoming
5419 edge, we should always have an edge from NEW_HEAD to SECOND. */
5420 gcc_assert (e2 != NULL);
5422 /* Browse all 'second' basic block phi nodes and add phi args to
5423 edge 'e' for 'first' head. PHI args are always in correct order. */
5425 for (phi2 = phi_nodes (second), phi1 = phi_nodes (first);
5427 phi2 = PHI_CHAIN (phi2), phi1 = PHI_CHAIN (phi1))
5429 tree def = PHI_ARG_DEF (phi2, e2->dest_idx);
5430 add_phi_arg (phi1, def, e);
5434 /* Adds a if else statement to COND_BB with condition COND_EXPR.
5435 SECOND_HEAD is the destination of the THEN and FIRST_HEAD is
5436 the destination of the ELSE part. */
5438 tree_lv_add_condition_to_bb (basic_block first_head, basic_block second_head,
5439 basic_block cond_bb, void *cond_e)
5441 block_stmt_iterator bsi;
5442 tree goto1 = NULL_TREE;
5443 tree goto2 = NULL_TREE;
5444 tree new_cond_expr = NULL_TREE;
5445 tree cond_expr = (tree) cond_e;
5448 /* Build new conditional expr */
5449 goto1 = build1 (GOTO_EXPR, void_type_node, tree_block_label (first_head));
5450 goto2 = build1 (GOTO_EXPR, void_type_node, tree_block_label (second_head));
5451 new_cond_expr = build3 (COND_EXPR, void_type_node, cond_expr, goto1, goto2);
5453 /* Add new cond in cond_bb. */
5454 bsi = bsi_start (cond_bb);
5455 bsi_insert_after (&bsi, new_cond_expr, BSI_NEW_STMT);
5456 /* Adjust edges appropriately to connect new head with first head
5457 as well as second head. */
5458 e0 = single_succ_edge (cond_bb);
5459 e0->flags &= ~EDGE_FALLTHRU;
5460 e0->flags |= EDGE_FALSE_VALUE;
5463 struct cfg_hooks tree_cfg_hooks = {
5465 tree_verify_flow_info,
5466 tree_dump_bb, /* dump_bb */
5467 create_bb, /* create_basic_block */
5468 tree_redirect_edge_and_branch,/* redirect_edge_and_branch */
5469 tree_redirect_edge_and_branch_force,/* redirect_edge_and_branch_force */
5470 remove_bb, /* delete_basic_block */
5471 tree_split_block, /* split_block */
5472 tree_move_block_after, /* move_block_after */
5473 tree_can_merge_blocks_p, /* can_merge_blocks_p */
5474 tree_merge_blocks, /* merge_blocks */
5475 tree_predict_edge, /* predict_edge */
5476 tree_predicted_by_p, /* predicted_by_p */
5477 tree_can_duplicate_bb_p, /* can_duplicate_block_p */
5478 tree_duplicate_bb, /* duplicate_block */
5479 tree_split_edge, /* split_edge */
5480 tree_make_forwarder_block, /* make_forward_block */
5481 NULL, /* tidy_fallthru_edge */
5482 tree_block_ends_with_call_p, /* block_ends_with_call_p */
5483 tree_block_ends_with_condjump_p, /* block_ends_with_condjump_p */
5484 tree_flow_call_edges_add, /* flow_call_edges_add */
5485 tree_execute_on_growing_pred, /* execute_on_growing_pred */
5486 tree_execute_on_shrinking_pred, /* execute_on_shrinking_pred */
5487 tree_duplicate_loop_to_header_edge, /* duplicate loop for trees */
5488 tree_lv_add_condition_to_bb, /* lv_add_condition_to_bb */
5489 tree_lv_adjust_loop_header_phi, /* lv_adjust_loop_header_phi*/
5490 extract_true_false_edges_from_block, /* extract_cond_bb_edges */
5491 flush_pending_stmts /* flush_pending_stmts */
5495 /* Split all critical edges. */
5498 split_critical_edges (void)
5504 /* split_edge can redirect edges out of SWITCH_EXPRs, which can get
5505 expensive. So we want to enable recording of edge to CASE_LABEL_EXPR
5506 mappings around the calls to split_edge. */
5507 start_recording_case_labels ();
5510 FOR_EACH_EDGE (e, ei, bb->succs)
5511 if (EDGE_CRITICAL_P (e) && !(e->flags & EDGE_ABNORMAL))
5516 end_recording_case_labels ();
5519 struct tree_opt_pass pass_split_crit_edges =
5521 "crited", /* name */
5523 split_critical_edges, /* execute */
5526 0, /* static_pass_number */
5527 TV_TREE_SPLIT_EDGES, /* tv_id */
5528 PROP_cfg, /* properties required */
5529 PROP_no_crit_edges, /* properties_provided */
5530 0, /* properties_destroyed */
5531 0, /* todo_flags_start */
5532 TODO_dump_func, /* todo_flags_finish */
5537 /* Return EXP if it is a valid GIMPLE rvalue, else gimplify it into
5538 a temporary, make sure and register it to be renamed if necessary,
5539 and finally return the temporary. Put the statements to compute
5540 EXP before the current statement in BSI. */
5543 gimplify_val (block_stmt_iterator *bsi, tree type, tree exp)
5545 tree t, new_stmt, orig_stmt;
5547 if (is_gimple_val (exp))
5550 t = make_rename_temp (type, NULL);
5551 new_stmt = build (MODIFY_EXPR, type, t, exp);
5553 orig_stmt = bsi_stmt (*bsi);
5554 SET_EXPR_LOCUS (new_stmt, EXPR_LOCUS (orig_stmt));
5555 TREE_BLOCK (new_stmt) = TREE_BLOCK (orig_stmt);
5557 bsi_insert_before (bsi, new_stmt, BSI_SAME_STMT);
5562 /* Build a ternary operation and gimplify it. Emit code before BSI.
5563 Return the gimple_val holding the result. */
5566 gimplify_build3 (block_stmt_iterator *bsi, enum tree_code code,
5567 tree type, tree a, tree b, tree c)
5571 ret = fold (build3 (code, type, a, b, c));
5574 return gimplify_val (bsi, type, ret);
5577 /* Build a binary operation and gimplify it. Emit code before BSI.
5578 Return the gimple_val holding the result. */
5581 gimplify_build2 (block_stmt_iterator *bsi, enum tree_code code,
5582 tree type, tree a, tree b)
5586 ret = fold (build2 (code, type, a, b));
5589 return gimplify_val (bsi, type, ret);
5592 /* Build a unary operation and gimplify it. Emit code before BSI.
5593 Return the gimple_val holding the result. */
5596 gimplify_build1 (block_stmt_iterator *bsi, enum tree_code code, tree type,
5601 ret = fold (build1 (code, type, a));
5604 return gimplify_val (bsi, type, ret);
5609 /* Emit return warnings. */
5612 execute_warn_function_return (void)
5614 #ifdef USE_MAPPED_LOCATION
5615 source_location location;
5623 if (warn_missing_noreturn
5624 && !TREE_THIS_VOLATILE (cfun->decl)
5625 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) == 0
5626 && !lang_hooks.function.missing_noreturn_ok_p (cfun->decl))
5627 warning (0, "%Jfunction might be possible candidate for "
5628 "attribute %<noreturn%>",
5631 /* If we have a path to EXIT, then we do return. */
5632 if (TREE_THIS_VOLATILE (cfun->decl)
5633 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) > 0)
5635 #ifdef USE_MAPPED_LOCATION
5636 location = UNKNOWN_LOCATION;
5640 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
5642 last = last_stmt (e->src);
5643 if (TREE_CODE (last) == RETURN_EXPR
5644 #ifdef USE_MAPPED_LOCATION
5645 && (location = EXPR_LOCATION (last)) != UNKNOWN_LOCATION)
5647 && (locus = EXPR_LOCUS (last)) != NULL)
5651 #ifdef USE_MAPPED_LOCATION
5652 if (location == UNKNOWN_LOCATION)
5653 location = cfun->function_end_locus;
5654 warning (0, "%H%<noreturn%> function does return", &location);
5657 locus = &cfun->function_end_locus;
5658 warning (0, "%H%<noreturn%> function does return", locus);
5662 /* If we see "return;" in some basic block, then we do reach the end
5663 without returning a value. */
5664 else if (warn_return_type
5665 && !TREE_NO_WARNING (cfun->decl)
5666 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) > 0
5667 && !VOID_TYPE_P (TREE_TYPE (TREE_TYPE (cfun->decl))))
5669 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
5671 tree last = last_stmt (e->src);
5672 if (TREE_CODE (last) == RETURN_EXPR
5673 && TREE_OPERAND (last, 0) == NULL)
5675 #ifdef USE_MAPPED_LOCATION
5676 location = EXPR_LOCATION (last);
5677 if (location == UNKNOWN_LOCATION)
5678 location = cfun->function_end_locus;
5679 warning (0, "%Hcontrol reaches end of non-void function", &location);
5681 locus = EXPR_LOCUS (last);
5683 locus = &cfun->function_end_locus;
5684 warning (0, "%Hcontrol reaches end of non-void function", locus);
5686 TREE_NO_WARNING (cfun->decl) = 1;
5694 /* Given a basic block B which ends with a conditional and has
5695 precisely two successors, determine which of the edges is taken if
5696 the conditional is true and which is taken if the conditional is
5697 false. Set TRUE_EDGE and FALSE_EDGE appropriately. */
5700 extract_true_false_edges_from_block (basic_block b,
5704 edge e = EDGE_SUCC (b, 0);
5706 if (e->flags & EDGE_TRUE_VALUE)
5709 *false_edge = EDGE_SUCC (b, 1);
5714 *true_edge = EDGE_SUCC (b, 1);
5718 struct tree_opt_pass pass_warn_function_return =
5722 execute_warn_function_return, /* execute */
5725 0, /* static_pass_number */
5727 PROP_cfg, /* properties_required */
5728 0, /* properties_provided */
5729 0, /* properties_destroyed */
5730 0, /* todo_flags_start */
5731 0, /* todo_flags_finish */