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 /* Mapping of labels to their associated blocks. This can greatly speed up
58 building of the CFG in code with lots of gotos. */
59 static GTY(()) varray_type label_to_block_map;
61 /* This hash table allows us to efficiently lookup all CASE_LABEL_EXPRs
62 which use a particular edge. The CASE_LABEL_EXPRs are chained together
63 via their TREE_CHAIN field, which we clear after we're done with the
64 hash table to prevent problems with duplication of SWITCH_EXPRs.
66 Access to this list of CASE_LABEL_EXPRs allows us to efficiently
67 update the case vector in response to edge redirections.
69 Right now this table is set up and torn down at key points in the
70 compilation process. It would be nice if we could make the table
71 more persistent. The key is getting notification of changes to
72 the CFG (particularly edge removal, creation and redirection). */
74 struct edge_to_cases_elt
76 /* The edge itself. Necessary for hashing and equality tests. */
79 /* The case labels associated with this edge. We link these up via
80 their TREE_CHAIN field, then we wipe out the TREE_CHAIN fields
81 when we destroy the hash table. This prevents problems when copying
86 static htab_t edge_to_cases;
91 long num_merged_labels;
94 static struct cfg_stats_d cfg_stats;
96 /* Nonzero if we found a computed goto while building basic blocks. */
97 static bool found_computed_goto;
99 /* Basic blocks and flowgraphs. */
100 static basic_block create_bb (void *, void *, basic_block);
101 static void create_block_annotation (basic_block);
102 static void free_blocks_annotations (void);
103 static void clear_blocks_annotations (void);
104 static void make_blocks (tree);
105 static void factor_computed_gotos (void);
108 static void make_edges (void);
109 static void make_ctrl_stmt_edges (basic_block);
110 static void make_exit_edges (basic_block);
111 static void make_cond_expr_edges (basic_block);
112 static void make_switch_expr_edges (basic_block);
113 static void make_goto_expr_edges (basic_block);
114 static edge tree_redirect_edge_and_branch (edge, basic_block);
115 static edge tree_try_redirect_by_replacing_jump (edge, basic_block);
116 static void split_critical_edges (void);
117 static bool remove_fallthru_edge (VEC(edge) *);
119 /* Various helpers. */
120 static inline bool stmt_starts_bb_p (tree, tree);
121 static int tree_verify_flow_info (void);
122 static void tree_make_forwarder_block (edge);
123 static bool tree_forwarder_block_p (basic_block, bool);
124 static void tree_cfg2vcg (FILE *);
126 /* Flowgraph optimization and cleanup. */
127 static void tree_merge_blocks (basic_block, basic_block);
128 static bool tree_can_merge_blocks_p (basic_block, basic_block);
129 static void remove_bb (basic_block);
130 static bool cleanup_control_flow (void);
131 static bool cleanup_control_expr_graph (basic_block, block_stmt_iterator);
132 static edge find_taken_edge_cond_expr (basic_block, tree);
133 static edge find_taken_edge_switch_expr (basic_block, tree);
134 static tree find_case_label_for_value (tree, tree);
135 static bool phi_alternatives_equal (basic_block, edge, edge);
136 static bool cleanup_forwarder_blocks (void);
139 /*---------------------------------------------------------------------------
141 ---------------------------------------------------------------------------*/
143 /* Entry point to the CFG builder for trees. TP points to the list of
144 statements to be added to the flowgraph. */
147 build_tree_cfg (tree *tp)
149 /* Register specific tree functions. */
150 tree_register_cfg_hooks ();
152 /* Initialize rbi_pool. */
155 /* Initialize the basic block array. */
157 profile_status = PROFILE_ABSENT;
159 last_basic_block = 0;
160 VARRAY_BB_INIT (basic_block_info, initial_cfg_capacity, "basic_block_info");
161 memset ((void *) &cfg_stats, 0, sizeof (cfg_stats));
163 /* Build a mapping of labels to their associated blocks. */
164 VARRAY_BB_INIT (label_to_block_map, initial_cfg_capacity,
165 "label to block map");
167 ENTRY_BLOCK_PTR->next_bb = EXIT_BLOCK_PTR;
168 EXIT_BLOCK_PTR->prev_bb = ENTRY_BLOCK_PTR;
170 found_computed_goto = 0;
173 /* Computed gotos are hell to deal with, especially if there are
174 lots of them with a large number of destinations. So we factor
175 them to a common computed goto location before we build the
176 edge list. After we convert back to normal form, we will un-factor
177 the computed gotos since factoring introduces an unwanted jump. */
178 if (found_computed_goto)
179 factor_computed_gotos ();
181 /* Make sure there is always at least one block, even if it's empty. */
182 if (n_basic_blocks == 0)
183 create_empty_bb (ENTRY_BLOCK_PTR);
185 create_block_annotation (ENTRY_BLOCK_PTR);
186 create_block_annotation (EXIT_BLOCK_PTR);
188 /* Adjust the size of the array. */
189 VARRAY_GROW (basic_block_info, n_basic_blocks);
191 /* To speed up statement iterator walks, we first purge dead labels. */
192 cleanup_dead_labels ();
194 /* Group case nodes to reduce the number of edges.
195 We do this after cleaning up dead labels because otherwise we miss
196 a lot of obvious case merging opportunities. */
197 group_case_labels ();
199 /* Create the edges of the flowgraph. */
202 /* Debugging dumps. */
204 /* Write the flowgraph to a VCG file. */
206 int local_dump_flags;
207 FILE *dump_file = dump_begin (TDI_vcg, &local_dump_flags);
210 tree_cfg2vcg (dump_file);
211 dump_end (TDI_vcg, dump_file);
215 /* Dump a textual representation of the flowgraph. */
217 dump_tree_cfg (dump_file, dump_flags);
221 execute_build_cfg (void)
223 build_tree_cfg (&DECL_SAVED_TREE (current_function_decl));
226 struct tree_opt_pass pass_build_cfg =
230 execute_build_cfg, /* execute */
233 0, /* static_pass_number */
234 TV_TREE_CFG, /* tv_id */
235 PROP_gimple_leh, /* properties_required */
236 PROP_cfg, /* properties_provided */
237 0, /* properties_destroyed */
238 0, /* todo_flags_start */
239 TODO_verify_stmts, /* todo_flags_finish */
243 /* Search the CFG for any computed gotos. If found, factor them to a
244 common computed goto site. Also record the location of that site so
245 that we can un-factor the gotos after we have converted back to
249 factor_computed_gotos (void)
252 tree factored_label_decl = NULL;
254 tree factored_computed_goto_label = NULL;
255 tree factored_computed_goto = NULL;
257 /* We know there are one or more computed gotos in this function.
258 Examine the last statement in each basic block to see if the block
259 ends with a computed goto. */
263 block_stmt_iterator bsi = bsi_last (bb);
268 last = bsi_stmt (bsi);
270 /* Ignore the computed goto we create when we factor the original
272 if (last == factored_computed_goto)
275 /* If the last statement is a computed goto, factor it. */
276 if (computed_goto_p (last))
280 /* The first time we find a computed goto we need to create
281 the factored goto block and the variable each original
282 computed goto will use for their goto destination. */
283 if (! factored_computed_goto)
285 basic_block new_bb = create_empty_bb (bb);
286 block_stmt_iterator new_bsi = bsi_start (new_bb);
288 /* Create the destination of the factored goto. Each original
289 computed goto will put its desired destination into this
290 variable and jump to the label we create immediately
292 var = create_tmp_var (ptr_type_node, "gotovar");
294 /* Build a label for the new block which will contain the
295 factored computed goto. */
296 factored_label_decl = create_artificial_label ();
297 factored_computed_goto_label
298 = build1 (LABEL_EXPR, void_type_node, factored_label_decl);
299 bsi_insert_after (&new_bsi, factored_computed_goto_label,
302 /* Build our new computed goto. */
303 factored_computed_goto = build1 (GOTO_EXPR, void_type_node, var);
304 bsi_insert_after (&new_bsi, factored_computed_goto,
308 /* Copy the original computed goto's destination into VAR. */
309 assignment = build (MODIFY_EXPR, ptr_type_node,
310 var, GOTO_DESTINATION (last));
311 bsi_insert_before (&bsi, assignment, BSI_SAME_STMT);
313 /* And re-vector the computed goto to the new destination. */
314 GOTO_DESTINATION (last) = factored_label_decl;
320 /* Create annotations for a single basic block. */
323 create_block_annotation (basic_block bb)
325 /* Verify that the tree_annotations field is clear. */
326 gcc_assert (!bb->tree_annotations);
327 bb->tree_annotations = ggc_alloc_cleared (sizeof (struct bb_ann_d));
331 /* Free the annotations for all the basic blocks. */
333 static void free_blocks_annotations (void)
335 clear_blocks_annotations ();
339 /* Clear the annotations for all the basic blocks. */
342 clear_blocks_annotations (void)
346 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb)
347 bb->tree_annotations = NULL;
351 /* Build a flowgraph for the statement_list STMT_LIST. */
354 make_blocks (tree stmt_list)
356 tree_stmt_iterator i = tsi_start (stmt_list);
358 bool start_new_block = true;
359 bool first_stmt_of_list = true;
360 basic_block bb = ENTRY_BLOCK_PTR;
362 while (!tsi_end_p (i))
369 /* If the statement starts a new basic block or if we have determined
370 in a previous pass that we need to create a new block for STMT, do
372 if (start_new_block || stmt_starts_bb_p (stmt, prev_stmt))
374 if (!first_stmt_of_list)
375 stmt_list = tsi_split_statement_list_before (&i);
376 bb = create_basic_block (stmt_list, NULL, bb);
377 start_new_block = false;
380 /* Now add STMT to BB and create the subgraphs for special statement
382 set_bb_for_stmt (stmt, bb);
384 if (computed_goto_p (stmt))
385 found_computed_goto = true;
387 /* If STMT is a basic block terminator, set START_NEW_BLOCK for the
389 if (stmt_ends_bb_p (stmt))
390 start_new_block = true;
393 first_stmt_of_list = false;
398 /* Create and return a new empty basic block after bb AFTER. */
401 create_bb (void *h, void *e, basic_block after)
407 /* Create and initialize a new basic block. Since alloc_block uses
408 ggc_alloc_cleared to allocate a basic block, we do not have to
409 clear the newly allocated basic block here. */
412 bb->index = last_basic_block;
414 bb->stmt_list = h ? h : alloc_stmt_list ();
416 /* Add the new block to the linked list of blocks. */
417 link_block (bb, after);
419 /* Grow the basic block array if needed. */
420 if ((size_t) last_basic_block == VARRAY_SIZE (basic_block_info))
422 size_t new_size = last_basic_block + (last_basic_block + 3) / 4;
423 VARRAY_GROW (basic_block_info, new_size);
426 /* Add the newly created block to the array. */
427 BASIC_BLOCK (last_basic_block) = bb;
429 create_block_annotation (bb);
434 initialize_bb_rbi (bb);
439 /*---------------------------------------------------------------------------
441 ---------------------------------------------------------------------------*/
443 /* Join all the blocks in the flowgraph. */
450 /* Create an edge from entry to the first block with executable
452 make_edge (ENTRY_BLOCK_PTR, BASIC_BLOCK (0), EDGE_FALLTHRU);
454 /* Traverse the basic block array placing edges. */
457 tree first = first_stmt (bb);
458 tree last = last_stmt (bb);
462 /* Edges for statements that always alter flow control. */
463 if (is_ctrl_stmt (last))
464 make_ctrl_stmt_edges (bb);
466 /* Edges for statements that sometimes alter flow control. */
467 if (is_ctrl_altering_stmt (last))
468 make_exit_edges (bb);
471 /* Finally, if no edges were created above, this is a regular
472 basic block that only needs a fallthru edge. */
473 if (EDGE_COUNT (bb->succs) == 0)
474 make_edge (bb, bb->next_bb, EDGE_FALLTHRU);
477 /* We do not care about fake edges, so remove any that the CFG
478 builder inserted for completeness. */
479 remove_fake_exit_edges ();
481 /* Clean up the graph and warn for unreachable code. */
486 /* Create edges for control statement at basic block BB. */
489 make_ctrl_stmt_edges (basic_block bb)
491 tree last = last_stmt (bb);
494 switch (TREE_CODE (last))
497 make_goto_expr_edges (bb);
501 make_edge (bb, EXIT_BLOCK_PTR, 0);
505 make_cond_expr_edges (bb);
509 make_switch_expr_edges (bb);
513 make_eh_edges (last);
514 /* Yet another NORETURN hack. */
515 if (EDGE_COUNT (bb->succs) == 0)
516 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
525 /* Create exit edges for statements in block BB that alter the flow of
526 control. Statements that alter the control flow are 'goto', 'return'
527 and calls to non-returning functions. */
530 make_exit_edges (basic_block bb)
532 tree last = last_stmt (bb), op;
535 switch (TREE_CODE (last))
538 /* If this function receives a nonlocal goto, then we need to
539 make edges from this call site to all the nonlocal goto
541 if (TREE_SIDE_EFFECTS (last)
542 && current_function_has_nonlocal_label)
543 make_goto_expr_edges (bb);
545 /* If this statement has reachable exception handlers, then
546 create abnormal edges to them. */
547 make_eh_edges (last);
549 /* Some calls are known not to return. For such calls we create
552 We really need to revamp how we build edges so that it's not
553 such a bloody pain to avoid creating edges for this case since
554 all we do is remove these edges when we're done building the
556 if (call_expr_flags (last) & ECF_NORETURN)
558 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
562 /* Don't forget the fall-thru edge. */
563 make_edge (bb, bb->next_bb, EDGE_FALLTHRU);
567 /* A MODIFY_EXPR may have a CALL_EXPR on its RHS and the CALL_EXPR
568 may have an abnormal edge. Search the RHS for this case and
569 create any required edges. */
570 op = get_call_expr_in (last);
571 if (op && TREE_SIDE_EFFECTS (op)
572 && current_function_has_nonlocal_label)
573 make_goto_expr_edges (bb);
575 make_eh_edges (last);
576 make_edge (bb, bb->next_bb, EDGE_FALLTHRU);
585 /* Create the edges for a COND_EXPR starting at block BB.
586 At this point, both clauses must contain only simple gotos. */
589 make_cond_expr_edges (basic_block bb)
591 tree entry = last_stmt (bb);
592 basic_block then_bb, else_bb;
593 tree then_label, else_label;
596 gcc_assert (TREE_CODE (entry) == COND_EXPR);
598 /* Entry basic blocks for each component. */
599 then_label = GOTO_DESTINATION (COND_EXPR_THEN (entry));
600 else_label = GOTO_DESTINATION (COND_EXPR_ELSE (entry));
601 then_bb = label_to_block (then_label);
602 else_bb = label_to_block (else_label);
604 make_edge (bb, then_bb, EDGE_TRUE_VALUE);
605 make_edge (bb, else_bb, EDGE_FALSE_VALUE);
608 /* Hashing routine for EDGE_TO_CASES. */
611 edge_to_cases_hash (const void *p)
613 edge e = ((struct edge_to_cases_elt *)p)->e;
615 /* Hash on the edge itself (which is a pointer). */
616 return htab_hash_pointer (e);
619 /* Equality routine for EDGE_TO_CASES, edges are unique, so testing
620 for equality is just a pointer comparison. */
623 edge_to_cases_eq (const void *p1, const void *p2)
625 edge e1 = ((struct edge_to_cases_elt *)p1)->e;
626 edge e2 = ((struct edge_to_cases_elt *)p2)->e;
631 /* Called for each element in the hash table (P) as we delete the
632 edge to cases hash table.
634 Clear all the TREE_CHAINs to prevent problems with copying of
635 SWITCH_EXPRs and structure sharing rules, then free the hash table
639 edge_to_cases_cleanup (void *p)
641 struct edge_to_cases_elt *elt = p;
644 for (t = elt->case_labels; t; t = next)
646 next = TREE_CHAIN (t);
647 TREE_CHAIN (t) = NULL;
652 /* Start recording information mapping edges to case labels. */
655 start_recording_case_labels (void)
657 gcc_assert (edge_to_cases == NULL);
659 edge_to_cases = htab_create (37,
662 edge_to_cases_cleanup);
665 /* Return nonzero if we are recording information for case labels. */
668 recording_case_labels_p (void)
670 return (edge_to_cases != NULL);
673 /* Stop recording information mapping edges to case labels and
674 remove any information we have recorded. */
676 end_recording_case_labels (void)
678 htab_delete (edge_to_cases);
679 edge_to_cases = NULL;
682 /* Record that CASE_LABEL (a CASE_LABEL_EXPR) references edge E. */
685 record_switch_edge (edge e, tree case_label)
687 struct edge_to_cases_elt *elt;
690 /* Build a hash table element so we can see if E is already
692 elt = xmalloc (sizeof (struct edge_to_cases_elt));
694 elt->case_labels = case_label;
696 slot = htab_find_slot (edge_to_cases, elt, INSERT);
700 /* E was not in the hash table. Install E into the hash table. */
705 /* E was already in the hash table. Free ELT as we do not need it
709 /* Get the entry stored in the hash table. */
710 elt = (struct edge_to_cases_elt *) *slot;
712 /* Add it to the chain of CASE_LABEL_EXPRs referencing E. */
713 TREE_CHAIN (case_label) = elt->case_labels;
714 elt->case_labels = case_label;
718 /* If we are inside a {start,end}_recording_cases block, then return
719 a chain of CASE_LABEL_EXPRs from T which reference E.
721 Otherwise return NULL. */
724 get_cases_for_edge (edge e, tree t)
726 struct edge_to_cases_elt elt, *elt_p;
731 /* If we are not recording cases, then we do not have CASE_LABEL_EXPR
732 chains available. Return NULL so the caller can detect this case. */
733 if (!recording_case_labels_p ())
738 elt.case_labels = NULL;
739 slot = htab_find_slot (edge_to_cases, &elt, NO_INSERT);
743 elt_p = (struct edge_to_cases_elt *)*slot;
744 return elt_p->case_labels;
747 /* If we did not find E in the hash table, then this must be the first
748 time we have been queried for information about E & T. Add all the
749 elements from T to the hash table then perform the query again. */
751 vec = SWITCH_LABELS (t);
752 n = TREE_VEC_LENGTH (vec);
753 for (i = 0; i < n; i++)
755 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
756 basic_block label_bb = label_to_block (lab);
757 record_switch_edge (find_edge (e->src, label_bb), TREE_VEC_ELT (vec, i));
762 /* Create the edges for a SWITCH_EXPR starting at block BB.
763 At this point, the switch body has been lowered and the
764 SWITCH_LABELS filled in, so this is in effect a multi-way branch. */
767 make_switch_expr_edges (basic_block bb)
769 tree entry = last_stmt (bb);
773 vec = SWITCH_LABELS (entry);
774 n = TREE_VEC_LENGTH (vec);
776 for (i = 0; i < n; ++i)
778 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
779 basic_block label_bb = label_to_block (lab);
780 make_edge (bb, label_bb, 0);
785 /* Return the basic block holding label DEST. */
788 label_to_block (tree dest)
790 int uid = LABEL_DECL_UID (dest);
792 /* We would die hard when faced by an undefined label. Emit a label to
793 the very first basic block. This will hopefully make even the dataflow
794 and undefined variable warnings quite right. */
795 if ((errorcount || sorrycount) && uid < 0)
797 block_stmt_iterator bsi = bsi_start (BASIC_BLOCK (0));
800 stmt = build1 (LABEL_EXPR, void_type_node, dest);
801 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
802 uid = LABEL_DECL_UID (dest);
804 return VARRAY_BB (label_to_block_map, uid);
808 /* Create edges for a goto statement at block BB. */
811 make_goto_expr_edges (basic_block bb)
814 basic_block target_bb;
816 block_stmt_iterator last = bsi_last (bb);
818 goto_t = bsi_stmt (last);
820 /* If the last statement is not a GOTO (i.e., it is a RETURN_EXPR,
821 CALL_EXPR or MODIFY_EXPR), then the edge is an abnormal edge resulting
822 from a nonlocal goto. */
823 if (TREE_CODE (goto_t) != GOTO_EXPR)
825 dest = error_mark_node;
830 dest = GOTO_DESTINATION (goto_t);
833 /* A GOTO to a local label creates normal edges. */
834 if (simple_goto_p (goto_t))
836 edge e = make_edge (bb, label_to_block (dest), EDGE_FALLTHRU);
837 #ifdef USE_MAPPED_LOCATION
838 e->goto_locus = EXPR_LOCATION (goto_t);
840 e->goto_locus = EXPR_LOCUS (goto_t);
846 /* Nothing more to do for nonlocal gotos. */
847 if (TREE_CODE (dest) == LABEL_DECL)
850 /* Computed gotos remain. */
853 /* Look for the block starting with the destination label. In the
854 case of a computed goto, make an edge to any label block we find
856 FOR_EACH_BB (target_bb)
858 block_stmt_iterator bsi;
860 for (bsi = bsi_start (target_bb); !bsi_end_p (bsi); bsi_next (&bsi))
862 tree target = bsi_stmt (bsi);
864 if (TREE_CODE (target) != LABEL_EXPR)
868 /* Computed GOTOs. Make an edge to every label block that has
869 been marked as a potential target for a computed goto. */
870 (FORCED_LABEL (LABEL_EXPR_LABEL (target)) && for_call == 0)
871 /* Nonlocal GOTO target. Make an edge to every label block
872 that has been marked as a potential target for a nonlocal
874 || (DECL_NONLOCAL (LABEL_EXPR_LABEL (target)) && for_call == 1))
876 make_edge (bb, target_bb, EDGE_ABNORMAL);
882 /* Degenerate case of computed goto with no labels. */
883 if (!for_call && EDGE_COUNT (bb->succs) == 0)
884 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
888 /*---------------------------------------------------------------------------
890 ---------------------------------------------------------------------------*/
892 /* Remove unreachable blocks and other miscellaneous clean up work. */
895 cleanup_tree_cfg (void)
899 timevar_push (TV_TREE_CLEANUP_CFG);
901 retval = cleanup_control_flow ();
902 retval |= delete_unreachable_blocks ();
904 /* cleanup_forwarder_blocks can redirect edges out of SWITCH_EXPRs,
905 which can get expensive. So we want to enable recording of edge
906 to CASE_LABEL_EXPR mappings around the call to
907 cleanup_forwarder_blocks. */
908 start_recording_case_labels ();
909 retval |= cleanup_forwarder_blocks ();
910 end_recording_case_labels ();
912 #ifdef ENABLE_CHECKING
915 gcc_assert (!cleanup_control_flow ());
916 gcc_assert (!delete_unreachable_blocks ());
917 gcc_assert (!cleanup_forwarder_blocks ());
921 /* Merging the blocks creates no new opportunities for the other
922 optimizations, so do it here. */
923 retval |= merge_seq_blocks ();
927 #ifdef ENABLE_CHECKING
930 timevar_pop (TV_TREE_CLEANUP_CFG);
935 /* Cleanup useless labels in basic blocks. This is something we wish
936 to do early because it allows us to group case labels before creating
937 the edges for the CFG, and it speeds up block statement iterators in
939 We only run this pass once, running it more than once is probably not
942 /* A map from basic block index to the leading label of that block. */
943 static tree *label_for_bb;
945 /* Callback for for_each_eh_region. Helper for cleanup_dead_labels. */
947 update_eh_label (struct eh_region *region)
949 tree old_label = get_eh_region_tree_label (region);
953 basic_block bb = label_to_block (old_label);
955 /* ??? After optimizing, there may be EH regions with labels
956 that have already been removed from the function body, so
957 there is no basic block for them. */
961 new_label = label_for_bb[bb->index];
962 set_eh_region_tree_label (region, new_label);
966 /* Given LABEL return the first label in the same basic block. */
968 main_block_label (tree label)
970 basic_block bb = label_to_block (label);
972 /* label_to_block possibly inserted undefined label into the chain. */
973 if (!label_for_bb[bb->index])
974 label_for_bb[bb->index] = label;
975 return label_for_bb[bb->index];
978 /* Cleanup redundant labels. This is a three-step process:
979 1) Find the leading label for each block.
980 2) Redirect all references to labels to the leading labels.
981 3) Cleanup all useless labels. */
984 cleanup_dead_labels (void)
987 label_for_bb = xcalloc (last_basic_block, sizeof (tree));
989 /* Find a suitable label for each block. We use the first user-defined
990 label if there is one, or otherwise just the first label we see. */
993 block_stmt_iterator i;
995 for (i = bsi_start (bb); !bsi_end_p (i); bsi_next (&i))
997 tree label, stmt = bsi_stmt (i);
999 if (TREE_CODE (stmt) != LABEL_EXPR)
1002 label = LABEL_EXPR_LABEL (stmt);
1004 /* If we have not yet seen a label for the current block,
1005 remember this one and see if there are more labels. */
1006 if (! label_for_bb[bb->index])
1008 label_for_bb[bb->index] = label;
1012 /* If we did see a label for the current block already, but it
1013 is an artificially created label, replace it if the current
1014 label is a user defined label. */
1015 if (! DECL_ARTIFICIAL (label)
1016 && DECL_ARTIFICIAL (label_for_bb[bb->index]))
1018 label_for_bb[bb->index] = label;
1024 /* Now redirect all jumps/branches to the selected label.
1025 First do so for each block ending in a control statement. */
1028 tree stmt = last_stmt (bb);
1032 switch (TREE_CODE (stmt))
1036 tree true_branch, false_branch;
1038 true_branch = COND_EXPR_THEN (stmt);
1039 false_branch = COND_EXPR_ELSE (stmt);
1041 GOTO_DESTINATION (true_branch)
1042 = main_block_label (GOTO_DESTINATION (true_branch));
1043 GOTO_DESTINATION (false_branch)
1044 = main_block_label (GOTO_DESTINATION (false_branch));
1052 tree vec = SWITCH_LABELS (stmt);
1053 size_t n = TREE_VEC_LENGTH (vec);
1055 /* Replace all destination labels. */
1056 for (i = 0; i < n; ++i)
1058 tree elt = TREE_VEC_ELT (vec, i);
1059 tree label = main_block_label (CASE_LABEL (elt));
1060 CASE_LABEL (elt) = label;
1065 /* We have to handle GOTO_EXPRs until they're removed, and we don't
1066 remove them until after we've created the CFG edges. */
1068 if (! computed_goto_p (stmt))
1070 GOTO_DESTINATION (stmt)
1071 = main_block_label (GOTO_DESTINATION (stmt));
1080 for_each_eh_region (update_eh_label);
1082 /* Finally, purge dead labels. All user-defined labels and labels that
1083 can be the target of non-local gotos are preserved. */
1086 block_stmt_iterator i;
1087 tree label_for_this_bb = label_for_bb[bb->index];
1089 if (! label_for_this_bb)
1092 for (i = bsi_start (bb); !bsi_end_p (i); )
1094 tree label, stmt = bsi_stmt (i);
1096 if (TREE_CODE (stmt) != LABEL_EXPR)
1099 label = LABEL_EXPR_LABEL (stmt);
1101 if (label == label_for_this_bb
1102 || ! DECL_ARTIFICIAL (label)
1103 || DECL_NONLOCAL (label))
1110 free (label_for_bb);
1113 /* Look for blocks ending in a multiway branch (a SWITCH_EXPR in GIMPLE),
1114 and scan the sorted vector of cases. Combine the ones jumping to the
1116 Eg. three separate entries 1: 2: 3: become one entry 1..3: */
1119 group_case_labels (void)
1125 tree stmt = last_stmt (bb);
1126 if (stmt && TREE_CODE (stmt) == SWITCH_EXPR)
1128 tree labels = SWITCH_LABELS (stmt);
1129 int old_size = TREE_VEC_LENGTH (labels);
1130 int i, j, new_size = old_size;
1131 tree default_case = TREE_VEC_ELT (labels, old_size - 1);
1134 /* The default label is always the last case in a switch
1135 statement after gimplification. */
1136 default_label = CASE_LABEL (default_case);
1138 /* Look for possible opportunities to merge cases.
1139 Ignore the last element of the label vector because it
1140 must be the default case. */
1142 while (i < old_size - 1)
1144 tree base_case, base_label, base_high, type;
1145 base_case = TREE_VEC_ELT (labels, i);
1147 gcc_assert (base_case);
1148 base_label = CASE_LABEL (base_case);
1150 /* Discard cases that have the same destination as the
1152 if (base_label == default_label)
1154 TREE_VEC_ELT (labels, i) = NULL_TREE;
1160 type = TREE_TYPE (CASE_LOW (base_case));
1161 base_high = CASE_HIGH (base_case) ?
1162 CASE_HIGH (base_case) : CASE_LOW (base_case);
1164 /* Try to merge case labels. Break out when we reach the end
1165 of the label vector or when we cannot merge the next case
1166 label with the current one. */
1167 while (i < old_size - 1)
1169 tree merge_case = TREE_VEC_ELT (labels, i);
1170 tree merge_label = CASE_LABEL (merge_case);
1171 tree t = int_const_binop (PLUS_EXPR, base_high,
1172 integer_one_node, 1);
1174 /* Merge the cases if they jump to the same place,
1175 and their ranges are consecutive. */
1176 if (merge_label == base_label
1177 && tree_int_cst_equal (CASE_LOW (merge_case), t))
1179 base_high = CASE_HIGH (merge_case) ?
1180 CASE_HIGH (merge_case) : CASE_LOW (merge_case);
1181 CASE_HIGH (base_case) = base_high;
1182 TREE_VEC_ELT (labels, i) = NULL_TREE;
1191 /* Compress the case labels in the label vector, and adjust the
1192 length of the vector. */
1193 for (i = 0, j = 0; i < new_size; i++)
1195 while (! TREE_VEC_ELT (labels, j))
1197 TREE_VEC_ELT (labels, i) = TREE_VEC_ELT (labels, j++);
1199 TREE_VEC_LENGTH (labels) = new_size;
1204 /* Checks whether we can merge block B into block A. */
1207 tree_can_merge_blocks_p (basic_block a, basic_block b)
1210 block_stmt_iterator bsi;
1212 if (EDGE_COUNT (a->succs) != 1)
1215 if (EDGE_SUCC (a, 0)->flags & EDGE_ABNORMAL)
1218 if (EDGE_SUCC (a, 0)->dest != b)
1221 if (EDGE_COUNT (b->preds) > 1)
1224 if (b == EXIT_BLOCK_PTR)
1227 /* If A ends by a statement causing exceptions or something similar, we
1228 cannot merge the blocks. */
1229 stmt = last_stmt (a);
1230 if (stmt && stmt_ends_bb_p (stmt))
1233 /* Do not allow a block with only a non-local label to be merged. */
1234 if (stmt && TREE_CODE (stmt) == LABEL_EXPR
1235 && DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)))
1238 /* There may be no phi nodes at the start of b. Most of these degenerate
1239 phi nodes should be cleaned up by kill_redundant_phi_nodes. */
1243 /* Do not remove user labels. */
1244 for (bsi = bsi_start (b); !bsi_end_p (bsi); bsi_next (&bsi))
1246 stmt = bsi_stmt (bsi);
1247 if (TREE_CODE (stmt) != LABEL_EXPR)
1249 if (!DECL_ARTIFICIAL (LABEL_EXPR_LABEL (stmt)))
1257 /* Merge block B into block A. */
1260 tree_merge_blocks (basic_block a, basic_block b)
1262 block_stmt_iterator bsi;
1263 tree_stmt_iterator last;
1266 fprintf (dump_file, "Merging blocks %d and %d\n", a->index, b->index);
1268 /* Ensure that B follows A. */
1269 move_block_after (b, a);
1271 gcc_assert (EDGE_SUCC (a, 0)->flags & EDGE_FALLTHRU);
1272 gcc_assert (!last_stmt (a) || !stmt_ends_bb_p (last_stmt (a)));
1274 /* Remove labels from B and set bb_for_stmt to A for other statements. */
1275 for (bsi = bsi_start (b); !bsi_end_p (bsi);)
1277 if (TREE_CODE (bsi_stmt (bsi)) == LABEL_EXPR)
1281 set_bb_for_stmt (bsi_stmt (bsi), a);
1286 /* Merge the chains. */
1287 last = tsi_last (a->stmt_list);
1288 tsi_link_after (&last, b->stmt_list, TSI_NEW_STMT);
1289 b->stmt_list = NULL;
1293 /* Walk the function tree removing unnecessary statements.
1295 * Empty statement nodes are removed
1297 * Unnecessary TRY_FINALLY and TRY_CATCH blocks are removed
1299 * Unnecessary COND_EXPRs are removed
1301 * Some unnecessary BIND_EXPRs are removed
1303 Clearly more work could be done. The trick is doing the analysis
1304 and removal fast enough to be a net improvement in compile times.
1306 Note that when we remove a control structure such as a COND_EXPR
1307 BIND_EXPR, or TRY block, we will need to repeat this optimization pass
1308 to ensure we eliminate all the useless code. */
1319 static void remove_useless_stmts_1 (tree *, struct rus_data *);
1322 remove_useless_stmts_warn_notreached (tree stmt)
1324 if (EXPR_HAS_LOCATION (stmt))
1326 location_t loc = EXPR_LOCATION (stmt);
1327 if (LOCATION_LINE (loc) > 0)
1329 warning ("%Hwill never be executed", &loc);
1334 switch (TREE_CODE (stmt))
1336 case STATEMENT_LIST:
1338 tree_stmt_iterator i;
1339 for (i = tsi_start (stmt); !tsi_end_p (i); tsi_next (&i))
1340 if (remove_useless_stmts_warn_notreached (tsi_stmt (i)))
1346 if (remove_useless_stmts_warn_notreached (COND_EXPR_COND (stmt)))
1348 if (remove_useless_stmts_warn_notreached (COND_EXPR_THEN (stmt)))
1350 if (remove_useless_stmts_warn_notreached (COND_EXPR_ELSE (stmt)))
1354 case TRY_FINALLY_EXPR:
1355 case TRY_CATCH_EXPR:
1356 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt, 0)))
1358 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt, 1)))
1363 return remove_useless_stmts_warn_notreached (CATCH_BODY (stmt));
1364 case EH_FILTER_EXPR:
1365 return remove_useless_stmts_warn_notreached (EH_FILTER_FAILURE (stmt));
1367 return remove_useless_stmts_warn_notreached (BIND_EXPR_BLOCK (stmt));
1370 /* Not a live container. */
1378 remove_useless_stmts_cond (tree *stmt_p, struct rus_data *data)
1380 tree then_clause, else_clause, cond;
1381 bool save_has_label, then_has_label, else_has_label;
1383 save_has_label = data->has_label;
1384 data->has_label = false;
1385 data->last_goto = NULL;
1387 remove_useless_stmts_1 (&COND_EXPR_THEN (*stmt_p), data);
1389 then_has_label = data->has_label;
1390 data->has_label = false;
1391 data->last_goto = NULL;
1393 remove_useless_stmts_1 (&COND_EXPR_ELSE (*stmt_p), data);
1395 else_has_label = data->has_label;
1396 data->has_label = save_has_label | then_has_label | else_has_label;
1398 then_clause = COND_EXPR_THEN (*stmt_p);
1399 else_clause = COND_EXPR_ELSE (*stmt_p);
1400 cond = fold (COND_EXPR_COND (*stmt_p));
1402 /* If neither arm does anything at all, we can remove the whole IF. */
1403 if (!TREE_SIDE_EFFECTS (then_clause) && !TREE_SIDE_EFFECTS (else_clause))
1405 *stmt_p = build_empty_stmt ();
1406 data->repeat = true;
1409 /* If there are no reachable statements in an arm, then we can
1410 zap the entire conditional. */
1411 else if (integer_nonzerop (cond) && !else_has_label)
1413 if (warn_notreached)
1414 remove_useless_stmts_warn_notreached (else_clause);
1415 *stmt_p = then_clause;
1416 data->repeat = true;
1418 else if (integer_zerop (cond) && !then_has_label)
1420 if (warn_notreached)
1421 remove_useless_stmts_warn_notreached (then_clause);
1422 *stmt_p = else_clause;
1423 data->repeat = true;
1426 /* Check a couple of simple things on then/else with single stmts. */
1429 tree then_stmt = expr_only (then_clause);
1430 tree else_stmt = expr_only (else_clause);
1432 /* Notice branches to a common destination. */
1433 if (then_stmt && else_stmt
1434 && TREE_CODE (then_stmt) == GOTO_EXPR
1435 && TREE_CODE (else_stmt) == GOTO_EXPR
1436 && (GOTO_DESTINATION (then_stmt) == GOTO_DESTINATION (else_stmt)))
1438 *stmt_p = then_stmt;
1439 data->repeat = true;
1442 /* If the THEN/ELSE clause merely assigns a value to a variable or
1443 parameter which is already known to contain that value, then
1444 remove the useless THEN/ELSE clause. */
1445 else if (TREE_CODE (cond) == VAR_DECL || TREE_CODE (cond) == PARM_DECL)
1448 && TREE_CODE (else_stmt) == MODIFY_EXPR
1449 && TREE_OPERAND (else_stmt, 0) == cond
1450 && integer_zerop (TREE_OPERAND (else_stmt, 1)))
1451 COND_EXPR_ELSE (*stmt_p) = alloc_stmt_list ();
1453 else if ((TREE_CODE (cond) == EQ_EXPR || TREE_CODE (cond) == NE_EXPR)
1454 && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL
1455 || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL)
1456 && TREE_CONSTANT (TREE_OPERAND (cond, 1)))
1458 tree stmt = (TREE_CODE (cond) == EQ_EXPR
1459 ? then_stmt : else_stmt);
1460 tree *location = (TREE_CODE (cond) == EQ_EXPR
1461 ? &COND_EXPR_THEN (*stmt_p)
1462 : &COND_EXPR_ELSE (*stmt_p));
1465 && TREE_CODE (stmt) == MODIFY_EXPR
1466 && TREE_OPERAND (stmt, 0) == TREE_OPERAND (cond, 0)
1467 && TREE_OPERAND (stmt, 1) == TREE_OPERAND (cond, 1))
1468 *location = alloc_stmt_list ();
1472 /* Protect GOTOs in the arm of COND_EXPRs from being removed. They
1473 would be re-introduced during lowering. */
1474 data->last_goto = NULL;
1479 remove_useless_stmts_tf (tree *stmt_p, struct rus_data *data)
1481 bool save_may_branch, save_may_throw;
1482 bool this_may_branch, this_may_throw;
1484 /* Collect may_branch and may_throw information for the body only. */
1485 save_may_branch = data->may_branch;
1486 save_may_throw = data->may_throw;
1487 data->may_branch = false;
1488 data->may_throw = false;
1489 data->last_goto = NULL;
1491 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 0), data);
1493 this_may_branch = data->may_branch;
1494 this_may_throw = data->may_throw;
1495 data->may_branch |= save_may_branch;
1496 data->may_throw |= save_may_throw;
1497 data->last_goto = NULL;
1499 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 1), data);
1501 /* If the body is empty, then we can emit the FINALLY block without
1502 the enclosing TRY_FINALLY_EXPR. */
1503 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 0)))
1505 *stmt_p = TREE_OPERAND (*stmt_p, 1);
1506 data->repeat = true;
1509 /* If the handler is empty, then we can emit the TRY block without
1510 the enclosing TRY_FINALLY_EXPR. */
1511 else if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 1)))
1513 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1514 data->repeat = true;
1517 /* If the body neither throws, nor branches, then we can safely
1518 string the TRY and FINALLY blocks together. */
1519 else if (!this_may_branch && !this_may_throw)
1521 tree stmt = *stmt_p;
1522 *stmt_p = TREE_OPERAND (stmt, 0);
1523 append_to_statement_list (TREE_OPERAND (stmt, 1), stmt_p);
1524 data->repeat = true;
1530 remove_useless_stmts_tc (tree *stmt_p, struct rus_data *data)
1532 bool save_may_throw, this_may_throw;
1533 tree_stmt_iterator i;
1536 /* Collect may_throw information for the body only. */
1537 save_may_throw = data->may_throw;
1538 data->may_throw = false;
1539 data->last_goto = NULL;
1541 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 0), data);
1543 this_may_throw = data->may_throw;
1544 data->may_throw = save_may_throw;
1546 /* If the body cannot throw, then we can drop the entire TRY_CATCH_EXPR. */
1547 if (!this_may_throw)
1549 if (warn_notreached)
1550 remove_useless_stmts_warn_notreached (TREE_OPERAND (*stmt_p, 1));
1551 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1552 data->repeat = true;
1556 /* Process the catch clause specially. We may be able to tell that
1557 no exceptions propagate past this point. */
1559 this_may_throw = true;
1560 i = tsi_start (TREE_OPERAND (*stmt_p, 1));
1561 stmt = tsi_stmt (i);
1562 data->last_goto = NULL;
1564 switch (TREE_CODE (stmt))
1567 for (; !tsi_end_p (i); tsi_next (&i))
1569 stmt = tsi_stmt (i);
1570 /* If we catch all exceptions, then the body does not
1571 propagate exceptions past this point. */
1572 if (CATCH_TYPES (stmt) == NULL)
1573 this_may_throw = false;
1574 data->last_goto = NULL;
1575 remove_useless_stmts_1 (&CATCH_BODY (stmt), data);
1579 case EH_FILTER_EXPR:
1580 if (EH_FILTER_MUST_NOT_THROW (stmt))
1581 this_may_throw = false;
1582 else if (EH_FILTER_TYPES (stmt) == NULL)
1583 this_may_throw = false;
1584 remove_useless_stmts_1 (&EH_FILTER_FAILURE (stmt), data);
1588 /* Otherwise this is a cleanup. */
1589 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 1), data);
1591 /* If the cleanup is empty, then we can emit the TRY block without
1592 the enclosing TRY_CATCH_EXPR. */
1593 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 1)))
1595 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1596 data->repeat = true;
1600 data->may_throw |= this_may_throw;
1605 remove_useless_stmts_bind (tree *stmt_p, struct rus_data *data)
1609 /* First remove anything underneath the BIND_EXPR. */
1610 remove_useless_stmts_1 (&BIND_EXPR_BODY (*stmt_p), data);
1612 /* If the BIND_EXPR has no variables, then we can pull everything
1613 up one level and remove the BIND_EXPR, unless this is the toplevel
1614 BIND_EXPR for the current function or an inlined function.
1616 When this situation occurs we will want to apply this
1617 optimization again. */
1618 block = BIND_EXPR_BLOCK (*stmt_p);
1619 if (BIND_EXPR_VARS (*stmt_p) == NULL_TREE
1620 && *stmt_p != DECL_SAVED_TREE (current_function_decl)
1622 || ! BLOCK_ABSTRACT_ORIGIN (block)
1623 || (TREE_CODE (BLOCK_ABSTRACT_ORIGIN (block))
1626 *stmt_p = BIND_EXPR_BODY (*stmt_p);
1627 data->repeat = true;
1633 remove_useless_stmts_goto (tree *stmt_p, struct rus_data *data)
1635 tree dest = GOTO_DESTINATION (*stmt_p);
1637 data->may_branch = true;
1638 data->last_goto = NULL;
1640 /* Record the last goto expr, so that we can delete it if unnecessary. */
1641 if (TREE_CODE (dest) == LABEL_DECL)
1642 data->last_goto = stmt_p;
1647 remove_useless_stmts_label (tree *stmt_p, struct rus_data *data)
1649 tree label = LABEL_EXPR_LABEL (*stmt_p);
1651 data->has_label = true;
1653 /* We do want to jump across non-local label receiver code. */
1654 if (DECL_NONLOCAL (label))
1655 data->last_goto = NULL;
1657 else if (data->last_goto && GOTO_DESTINATION (*data->last_goto) == label)
1659 *data->last_goto = build_empty_stmt ();
1660 data->repeat = true;
1663 /* ??? Add something here to delete unused labels. */
1667 /* If the function is "const" or "pure", then clear TREE_SIDE_EFFECTS on its
1668 decl. This allows us to eliminate redundant or useless
1669 calls to "const" functions.
1671 Gimplifier already does the same operation, but we may notice functions
1672 being const and pure once their calls has been gimplified, so we need
1673 to update the flag. */
1676 update_call_expr_flags (tree call)
1678 tree decl = get_callee_fndecl (call);
1681 if (call_expr_flags (call) & (ECF_CONST | ECF_PURE))
1682 TREE_SIDE_EFFECTS (call) = 0;
1683 if (TREE_NOTHROW (decl))
1684 TREE_NOTHROW (call) = 1;
1688 /* T is CALL_EXPR. Set current_function_calls_* flags. */
1691 notice_special_calls (tree t)
1693 int flags = call_expr_flags (t);
1695 if (flags & ECF_MAY_BE_ALLOCA)
1696 current_function_calls_alloca = true;
1697 if (flags & ECF_RETURNS_TWICE)
1698 current_function_calls_setjmp = true;
1702 /* Clear flags set by notice_special_calls. Used by dead code removal
1703 to update the flags. */
1706 clear_special_calls (void)
1708 current_function_calls_alloca = false;
1709 current_function_calls_setjmp = false;
1714 remove_useless_stmts_1 (tree *tp, struct rus_data *data)
1718 switch (TREE_CODE (t))
1721 remove_useless_stmts_cond (tp, data);
1724 case TRY_FINALLY_EXPR:
1725 remove_useless_stmts_tf (tp, data);
1728 case TRY_CATCH_EXPR:
1729 remove_useless_stmts_tc (tp, data);
1733 remove_useless_stmts_bind (tp, data);
1737 remove_useless_stmts_goto (tp, data);
1741 remove_useless_stmts_label (tp, data);
1746 data->last_goto = NULL;
1747 data->may_branch = true;
1752 data->last_goto = NULL;
1753 notice_special_calls (t);
1754 update_call_expr_flags (t);
1755 if (tree_could_throw_p (t))
1756 data->may_throw = true;
1760 data->last_goto = NULL;
1762 op = get_call_expr_in (t);
1765 update_call_expr_flags (op);
1766 notice_special_calls (op);
1768 if (tree_could_throw_p (t))
1769 data->may_throw = true;
1772 case STATEMENT_LIST:
1774 tree_stmt_iterator i = tsi_start (t);
1775 while (!tsi_end_p (i))
1778 if (IS_EMPTY_STMT (t))
1784 remove_useless_stmts_1 (tsi_stmt_ptr (i), data);
1787 if (TREE_CODE (t) == STATEMENT_LIST)
1789 tsi_link_before (&i, t, TSI_SAME_STMT);
1799 data->last_goto = NULL;
1803 data->last_goto = NULL;
1809 remove_useless_stmts (void)
1811 struct rus_data data;
1813 clear_special_calls ();
1817 memset (&data, 0, sizeof (data));
1818 remove_useless_stmts_1 (&DECL_SAVED_TREE (current_function_decl), &data);
1820 while (data.repeat);
1824 struct tree_opt_pass pass_remove_useless_stmts =
1826 "useless", /* name */
1828 remove_useless_stmts, /* execute */
1831 0, /* static_pass_number */
1833 PROP_gimple_any, /* properties_required */
1834 0, /* properties_provided */
1835 0, /* properties_destroyed */
1836 0, /* todo_flags_start */
1837 TODO_dump_func, /* todo_flags_finish */
1842 /* Remove obviously useless statements in basic block BB. */
1845 cfg_remove_useless_stmts_bb (basic_block bb)
1847 block_stmt_iterator bsi;
1848 tree stmt = NULL_TREE;
1849 tree cond, var = NULL_TREE, val = NULL_TREE;
1850 struct var_ann_d *ann;
1852 /* Check whether we come here from a condition, and if so, get the
1854 if (EDGE_COUNT (bb->preds) != 1
1855 || !(EDGE_PRED (bb, 0)->flags & (EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
1858 cond = COND_EXPR_COND (last_stmt (EDGE_PRED (bb, 0)->src));
1860 if (TREE_CODE (cond) == VAR_DECL || TREE_CODE (cond) == PARM_DECL)
1863 val = (EDGE_PRED (bb, 0)->flags & EDGE_FALSE_VALUE
1864 ? boolean_false_node : boolean_true_node);
1866 else if (TREE_CODE (cond) == TRUTH_NOT_EXPR
1867 && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL
1868 || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL))
1870 var = TREE_OPERAND (cond, 0);
1871 val = (EDGE_PRED (bb, 0)->flags & EDGE_FALSE_VALUE
1872 ? boolean_true_node : boolean_false_node);
1876 if (EDGE_PRED (bb, 0)->flags & EDGE_FALSE_VALUE)
1877 cond = invert_truthvalue (cond);
1878 if (TREE_CODE (cond) == EQ_EXPR
1879 && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL
1880 || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL)
1881 && (TREE_CODE (TREE_OPERAND (cond, 1)) == VAR_DECL
1882 || TREE_CODE (TREE_OPERAND (cond, 1)) == PARM_DECL
1883 || TREE_CONSTANT (TREE_OPERAND (cond, 1))))
1885 var = TREE_OPERAND (cond, 0);
1886 val = TREE_OPERAND (cond, 1);
1892 /* Only work for normal local variables. */
1893 ann = var_ann (var);
1896 || TREE_ADDRESSABLE (var))
1899 if (! TREE_CONSTANT (val))
1901 ann = var_ann (val);
1904 || TREE_ADDRESSABLE (val))
1908 /* Ignore floating point variables, since comparison behaves weird for
1910 if (FLOAT_TYPE_P (TREE_TYPE (var)))
1913 for (bsi = bsi_start (bb); !bsi_end_p (bsi);)
1915 stmt = bsi_stmt (bsi);
1917 /* If the THEN/ELSE clause merely assigns a value to a variable/parameter
1918 which is already known to contain that value, then remove the useless
1919 THEN/ELSE clause. */
1920 if (TREE_CODE (stmt) == MODIFY_EXPR
1921 && TREE_OPERAND (stmt, 0) == var
1922 && operand_equal_p (val, TREE_OPERAND (stmt, 1), 0))
1928 /* Invalidate the var if we encounter something that could modify it.
1929 Likewise for the value it was previously set to. Note that we only
1930 consider values that are either a VAR_DECL or PARM_DECL so we
1931 can test for conflict very simply. */
1932 if (TREE_CODE (stmt) == ASM_EXPR
1933 || (TREE_CODE (stmt) == MODIFY_EXPR
1934 && (TREE_OPERAND (stmt, 0) == var
1935 || TREE_OPERAND (stmt, 0) == val)))
1943 /* A CFG-aware version of remove_useless_stmts. */
1946 cfg_remove_useless_stmts (void)
1950 #ifdef ENABLE_CHECKING
1951 verify_flow_info ();
1956 cfg_remove_useless_stmts_bb (bb);
1961 /* Remove PHI nodes associated with basic block BB and all edges out of BB. */
1964 remove_phi_nodes_and_edges_for_unreachable_block (basic_block bb)
1968 /* Since this block is no longer reachable, we can just delete all
1969 of its PHI nodes. */
1970 phi = phi_nodes (bb);
1973 tree next = PHI_CHAIN (phi);
1974 remove_phi_node (phi, NULL_TREE, bb);
1978 /* Remove edges to BB's successors. */
1979 while (EDGE_COUNT (bb->succs) > 0)
1980 remove_edge (EDGE_SUCC (bb, 0));
1984 /* Remove statements of basic block BB. */
1987 remove_bb (basic_block bb)
1989 block_stmt_iterator i;
1990 source_locus loc = 0;
1994 fprintf (dump_file, "Removing basic block %d\n", bb->index);
1995 if (dump_flags & TDF_DETAILS)
1997 dump_bb (bb, dump_file, 0);
1998 fprintf (dump_file, "\n");
2002 /* Remove all the instructions in the block. */
2003 for (i = bsi_start (bb); !bsi_end_p (i);)
2005 tree stmt = bsi_stmt (i);
2006 if (TREE_CODE (stmt) == LABEL_EXPR
2007 && FORCED_LABEL (LABEL_EXPR_LABEL (stmt)))
2009 basic_block new_bb = bb->prev_bb;
2010 block_stmt_iterator new_bsi = bsi_start (new_bb);
2013 bsi_insert_before (&new_bsi, stmt, BSI_NEW_STMT);
2017 release_defs (stmt);
2019 set_bb_for_stmt (stmt, NULL);
2023 /* Don't warn for removed gotos. Gotos are often removed due to
2024 jump threading, thus resulting in bogus warnings. Not great,
2025 since this way we lose warnings for gotos in the original
2026 program that are indeed unreachable. */
2027 if (TREE_CODE (stmt) != GOTO_EXPR && EXPR_HAS_LOCATION (stmt) && !loc)
2031 #ifdef USE_MAPPED_LOCATION
2032 t = EXPR_LOCATION (stmt);
2034 t = EXPR_LOCUS (stmt);
2036 if (t && LOCATION_LINE (*t) > 0)
2041 /* If requested, give a warning that the first statement in the
2042 block is unreachable. We walk statements backwards in the
2043 loop above, so the last statement we process is the first statement
2045 if (warn_notreached && loc)
2046 #ifdef USE_MAPPED_LOCATION
2047 warning ("%Hwill never be executed", &loc);
2049 warning ("%Hwill never be executed", loc);
2052 remove_phi_nodes_and_edges_for_unreachable_block (bb);
2055 /* Try to remove superfluous control structures. */
2058 cleanup_control_flow (void)
2061 block_stmt_iterator bsi;
2062 bool retval = false;
2067 bsi = bsi_last (bb);
2069 if (bsi_end_p (bsi))
2072 stmt = bsi_stmt (bsi);
2073 if (TREE_CODE (stmt) == COND_EXPR
2074 || TREE_CODE (stmt) == SWITCH_EXPR)
2075 retval |= cleanup_control_expr_graph (bb, bsi);
2077 /* Check for indirect calls that have been turned into
2079 call = get_call_expr_in (stmt);
2081 && (call_expr_flags (call) & ECF_NORETURN) != 0
2082 && remove_fallthru_edge (bb->succs))
2084 free_dominance_info (CDI_DOMINATORS);
2092 /* Disconnect an unreachable block in the control expression starting
2096 cleanup_control_expr_graph (basic_block bb, block_stmt_iterator bsi)
2099 bool retval = false;
2100 tree expr = bsi_stmt (bsi), val;
2102 if (EDGE_COUNT (bb->succs) > 1)
2107 switch (TREE_CODE (expr))
2110 val = COND_EXPR_COND (expr);
2114 val = SWITCH_COND (expr);
2115 if (TREE_CODE (val) != INTEGER_CST)
2123 taken_edge = find_taken_edge (bb, val);
2127 /* Remove all the edges except the one that is always executed. */
2128 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2130 if (e != taken_edge)
2132 taken_edge->probability += e->probability;
2133 taken_edge->count += e->count;
2140 if (taken_edge->probability > REG_BR_PROB_BASE)
2141 taken_edge->probability = REG_BR_PROB_BASE;
2144 taken_edge = EDGE_SUCC (bb, 0);
2147 taken_edge->flags = EDGE_FALLTHRU;
2149 /* We removed some paths from the cfg. */
2150 free_dominance_info (CDI_DOMINATORS);
2155 /* Remove any fallthru edge from EV. Return true if an edge was removed. */
2158 remove_fallthru_edge (VEC(edge) *ev)
2163 FOR_EACH_EDGE (e, ei, ev)
2164 if ((e->flags & EDGE_FALLTHRU) != 0)
2172 /* Given a basic block BB ending with COND_EXPR or SWITCH_EXPR, and a
2173 predicate VAL, return the edge that will be taken out of the block.
2174 If VAL does not match a unique edge, NULL is returned. */
2177 find_taken_edge (basic_block bb, tree val)
2181 stmt = last_stmt (bb);
2184 gcc_assert (is_ctrl_stmt (stmt));
2187 /* If VAL is a predicate of the form N RELOP N, where N is an
2188 SSA_NAME, we can usually determine its truth value. */
2189 if (COMPARISON_CLASS_P (val))
2192 /* If VAL is not a constant, we can't determine which edge might
2194 if (!really_constant_p (val))
2197 if (TREE_CODE (stmt) == COND_EXPR)
2198 return find_taken_edge_cond_expr (bb, val);
2200 if (TREE_CODE (stmt) == SWITCH_EXPR)
2201 return find_taken_edge_switch_expr (bb, val);
2207 /* Given a constant value VAL and the entry block BB to a COND_EXPR
2208 statement, determine which of the two edges will be taken out of the
2209 block. Return NULL if either edge may be taken. */
2212 find_taken_edge_cond_expr (basic_block bb, tree val)
2214 edge true_edge, false_edge;
2216 extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
2218 /* Otherwise, try to determine which branch of the if() will be taken.
2219 If VAL is a constant but it can't be reduced to a 0 or a 1, then
2220 we don't really know which edge will be taken at runtime. This
2221 may happen when comparing addresses (e.g., if (&var1 == 4)). */
2222 if (integer_nonzerop (val))
2224 else if (integer_zerop (val))
2231 /* Given a constant value VAL and the entry block BB to a SWITCH_EXPR
2232 statement, determine which edge will be taken out of the block. Return
2233 NULL if any edge may be taken. */
2236 find_taken_edge_switch_expr (basic_block bb, tree val)
2238 tree switch_expr, taken_case;
2239 basic_block dest_bb;
2242 if (TREE_CODE (val) != INTEGER_CST)
2245 switch_expr = last_stmt (bb);
2246 taken_case = find_case_label_for_value (switch_expr, val);
2247 dest_bb = label_to_block (CASE_LABEL (taken_case));
2249 e = find_edge (bb, dest_bb);
2255 /* Return the CASE_LABEL_EXPR that SWITCH_EXPR will take for VAL.
2256 We can make optimal use here of the fact that the case labels are
2257 sorted: We can do a binary search for a case matching VAL. */
2260 find_case_label_for_value (tree switch_expr, tree val)
2262 tree vec = SWITCH_LABELS (switch_expr);
2263 size_t low, high, n = TREE_VEC_LENGTH (vec);
2264 tree default_case = TREE_VEC_ELT (vec, n - 1);
2266 for (low = -1, high = n - 1; high - low > 1; )
2268 size_t i = (high + low) / 2;
2269 tree t = TREE_VEC_ELT (vec, i);
2272 /* Cache the result of comparing CASE_LOW and val. */
2273 cmp = tree_int_cst_compare (CASE_LOW (t), val);
2280 if (CASE_HIGH (t) == NULL)
2282 /* A singe-valued case label. */
2288 /* A case range. We can only handle integer ranges. */
2289 if (cmp <= 0 && tree_int_cst_compare (CASE_HIGH (t), val) >= 0)
2294 return default_case;
2298 /* If all the PHI nodes in DEST have alternatives for E1 and E2 and
2299 those alternatives are equal in each of the PHI nodes, then return
2300 true, else return false. */
2303 phi_alternatives_equal (basic_block dest, edge e1, edge e2)
2305 int n1 = e1->dest_idx;
2306 int n2 = e2->dest_idx;
2309 for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi))
2311 tree val1 = PHI_ARG_DEF (phi, n1);
2312 tree val2 = PHI_ARG_DEF (phi, n2);
2314 gcc_assert (val1 != NULL_TREE);
2315 gcc_assert (val2 != NULL_TREE);
2317 if (!operand_equal_for_phi_arg_p (val1, val2))
2325 /*---------------------------------------------------------------------------
2327 ---------------------------------------------------------------------------*/
2329 /* Dump tree-specific information of block BB to file OUTF. */
2332 tree_dump_bb (basic_block bb, FILE *outf, int indent)
2334 dump_generic_bb (outf, bb, indent, TDF_VOPS);
2338 /* Dump a basic block on stderr. */
2341 debug_tree_bb (basic_block bb)
2343 dump_bb (bb, stderr, 0);
2347 /* Dump basic block with index N on stderr. */
2350 debug_tree_bb_n (int n)
2352 debug_tree_bb (BASIC_BLOCK (n));
2353 return BASIC_BLOCK (n);
2357 /* Dump the CFG on stderr.
2359 FLAGS are the same used by the tree dumping functions
2360 (see TDF_* in tree.h). */
2363 debug_tree_cfg (int flags)
2365 dump_tree_cfg (stderr, flags);
2369 /* Dump the program showing basic block boundaries on the given FILE.
2371 FLAGS are the same used by the tree dumping functions (see TDF_* in
2375 dump_tree_cfg (FILE *file, int flags)
2377 if (flags & TDF_DETAILS)
2379 const char *funcname
2380 = lang_hooks.decl_printable_name (current_function_decl, 2);
2383 fprintf (file, ";; Function %s\n\n", funcname);
2384 fprintf (file, ";; \n%d basic blocks, %d edges, last basic block %d.\n\n",
2385 n_basic_blocks, n_edges, last_basic_block);
2387 brief_dump_cfg (file);
2388 fprintf (file, "\n");
2391 if (flags & TDF_STATS)
2392 dump_cfg_stats (file);
2394 dump_function_to_file (current_function_decl, file, flags | TDF_BLOCKS);
2398 /* Dump CFG statistics on FILE. */
2401 dump_cfg_stats (FILE *file)
2403 static long max_num_merged_labels = 0;
2404 unsigned long size, total = 0;
2407 const char * const fmt_str = "%-30s%-13s%12s\n";
2408 const char * const fmt_str_1 = "%-30s%13d%11lu%c\n";
2409 const char * const fmt_str_3 = "%-43s%11lu%c\n";
2410 const char *funcname
2411 = lang_hooks.decl_printable_name (current_function_decl, 2);
2414 fprintf (file, "\nCFG Statistics for %s\n\n", funcname);
2416 fprintf (file, "---------------------------------------------------------\n");
2417 fprintf (file, fmt_str, "", " Number of ", "Memory");
2418 fprintf (file, fmt_str, "", " instances ", "used ");
2419 fprintf (file, "---------------------------------------------------------\n");
2421 size = n_basic_blocks * sizeof (struct basic_block_def);
2423 fprintf (file, fmt_str_1, "Basic blocks", n_basic_blocks,
2424 SCALE (size), LABEL (size));
2428 n_edges += EDGE_COUNT (bb->succs);
2429 size = n_edges * sizeof (struct edge_def);
2431 fprintf (file, fmt_str_1, "Edges", n_edges, SCALE (size), LABEL (size));
2433 size = n_basic_blocks * sizeof (struct bb_ann_d);
2435 fprintf (file, fmt_str_1, "Basic block annotations", n_basic_blocks,
2436 SCALE (size), LABEL (size));
2438 fprintf (file, "---------------------------------------------------------\n");
2439 fprintf (file, fmt_str_3, "Total memory used by CFG data", SCALE (total),
2441 fprintf (file, "---------------------------------------------------------\n");
2442 fprintf (file, "\n");
2444 if (cfg_stats.num_merged_labels > max_num_merged_labels)
2445 max_num_merged_labels = cfg_stats.num_merged_labels;
2447 fprintf (file, "Coalesced label blocks: %ld (Max so far: %ld)\n",
2448 cfg_stats.num_merged_labels, max_num_merged_labels);
2450 fprintf (file, "\n");
2454 /* Dump CFG statistics on stderr. Keep extern so that it's always
2455 linked in the final executable. */
2458 debug_cfg_stats (void)
2460 dump_cfg_stats (stderr);
2464 /* Dump the flowgraph to a .vcg FILE. */
2467 tree_cfg2vcg (FILE *file)
2472 const char *funcname
2473 = lang_hooks.decl_printable_name (current_function_decl, 2);
2475 /* Write the file header. */
2476 fprintf (file, "graph: { title: \"%s\"\n", funcname);
2477 fprintf (file, "node: { title: \"ENTRY\" label: \"ENTRY\" }\n");
2478 fprintf (file, "node: { title: \"EXIT\" label: \"EXIT\" }\n");
2480 /* Write blocks and edges. */
2481 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
2483 fprintf (file, "edge: { sourcename: \"ENTRY\" targetname: \"%d\"",
2486 if (e->flags & EDGE_FAKE)
2487 fprintf (file, " linestyle: dotted priority: 10");
2489 fprintf (file, " linestyle: solid priority: 100");
2491 fprintf (file, " }\n");
2497 enum tree_code head_code, end_code;
2498 const char *head_name, *end_name;
2501 tree first = first_stmt (bb);
2502 tree last = last_stmt (bb);
2506 head_code = TREE_CODE (first);
2507 head_name = tree_code_name[head_code];
2508 head_line = get_lineno (first);
2511 head_name = "no-statement";
2515 end_code = TREE_CODE (last);
2516 end_name = tree_code_name[end_code];
2517 end_line = get_lineno (last);
2520 end_name = "no-statement";
2522 fprintf (file, "node: { title: \"%d\" label: \"#%d\\n%s (%d)\\n%s (%d)\"}\n",
2523 bb->index, bb->index, head_name, head_line, end_name,
2526 FOR_EACH_EDGE (e, ei, bb->succs)
2528 if (e->dest == EXIT_BLOCK_PTR)
2529 fprintf (file, "edge: { sourcename: \"%d\" targetname: \"EXIT\"", bb->index);
2531 fprintf (file, "edge: { sourcename: \"%d\" targetname: \"%d\"", bb->index, e->dest->index);
2533 if (e->flags & EDGE_FAKE)
2534 fprintf (file, " priority: 10 linestyle: dotted");
2536 fprintf (file, " priority: 100 linestyle: solid");
2538 fprintf (file, " }\n");
2541 if (bb->next_bb != EXIT_BLOCK_PTR)
2545 fputs ("}\n\n", file);
2550 /*---------------------------------------------------------------------------
2551 Miscellaneous helpers
2552 ---------------------------------------------------------------------------*/
2554 /* Return true if T represents a stmt that always transfers control. */
2557 is_ctrl_stmt (tree t)
2559 return (TREE_CODE (t) == COND_EXPR
2560 || TREE_CODE (t) == SWITCH_EXPR
2561 || TREE_CODE (t) == GOTO_EXPR
2562 || TREE_CODE (t) == RETURN_EXPR
2563 || TREE_CODE (t) == RESX_EXPR);
2567 /* Return true if T is a statement that may alter the flow of control
2568 (e.g., a call to a non-returning function). */
2571 is_ctrl_altering_stmt (tree t)
2576 call = get_call_expr_in (t);
2579 /* A non-pure/const CALL_EXPR alters flow control if the current
2580 function has nonlocal labels. */
2581 if (TREE_SIDE_EFFECTS (call) && current_function_has_nonlocal_label)
2584 /* A CALL_EXPR also alters control flow if it does not return. */
2585 if (call_expr_flags (call) & ECF_NORETURN)
2589 /* If a statement can throw, it alters control flow. */
2590 return tree_can_throw_internal (t);
2594 /* Return true if T is a computed goto. */
2597 computed_goto_p (tree t)
2599 return (TREE_CODE (t) == GOTO_EXPR
2600 && TREE_CODE (GOTO_DESTINATION (t)) != LABEL_DECL);
2604 /* Checks whether EXPR is a simple local goto. */
2607 simple_goto_p (tree expr)
2609 return (TREE_CODE (expr) == GOTO_EXPR
2610 && TREE_CODE (GOTO_DESTINATION (expr)) == LABEL_DECL);
2614 /* Return true if T should start a new basic block. PREV_T is the
2615 statement preceding T. It is used when T is a label or a case label.
2616 Labels should only start a new basic block if their previous statement
2617 wasn't a label. Otherwise, sequence of labels would generate
2618 unnecessary basic blocks that only contain a single label. */
2621 stmt_starts_bb_p (tree t, tree prev_t)
2623 enum tree_code code;
2628 /* LABEL_EXPRs start a new basic block only if the preceding
2629 statement wasn't a label of the same type. This prevents the
2630 creation of consecutive blocks that have nothing but a single
2632 code = TREE_CODE (t);
2633 if (code == LABEL_EXPR)
2635 /* Nonlocal and computed GOTO targets always start a new block. */
2636 if (code == LABEL_EXPR
2637 && (DECL_NONLOCAL (LABEL_EXPR_LABEL (t))
2638 || FORCED_LABEL (LABEL_EXPR_LABEL (t))))
2641 if (prev_t && TREE_CODE (prev_t) == code)
2643 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (prev_t)))
2646 cfg_stats.num_merged_labels++;
2657 /* Return true if T should end a basic block. */
2660 stmt_ends_bb_p (tree t)
2662 return is_ctrl_stmt (t) || is_ctrl_altering_stmt (t);
2666 /* Add gotos that used to be represented implicitly in the CFG. */
2669 disband_implicit_edges (void)
2672 block_stmt_iterator last;
2679 last = bsi_last (bb);
2680 stmt = last_stmt (bb);
2682 if (stmt && TREE_CODE (stmt) == COND_EXPR)
2684 /* Remove superfluous gotos from COND_EXPR branches. Moved
2685 from cfg_remove_useless_stmts here since it violates the
2686 invariants for tree--cfg correspondence and thus fits better
2687 here where we do it anyway. */
2688 e = find_edge (bb, bb->next_bb);
2691 if (e->flags & EDGE_TRUE_VALUE)
2692 COND_EXPR_THEN (stmt) = build_empty_stmt ();
2693 else if (e->flags & EDGE_FALSE_VALUE)
2694 COND_EXPR_ELSE (stmt) = build_empty_stmt ();
2697 e->flags |= EDGE_FALLTHRU;
2703 if (stmt && TREE_CODE (stmt) == RETURN_EXPR)
2705 /* Remove the RETURN_EXPR if we may fall though to the exit
2707 gcc_assert (EDGE_COUNT (bb->succs) == 1);
2708 gcc_assert (EDGE_SUCC (bb, 0)->dest == EXIT_BLOCK_PTR);
2710 if (bb->next_bb == EXIT_BLOCK_PTR
2711 && !TREE_OPERAND (stmt, 0))
2714 EDGE_SUCC (bb, 0)->flags |= EDGE_FALLTHRU;
2719 /* There can be no fallthru edge if the last statement is a control
2721 if (stmt && is_ctrl_stmt (stmt))
2724 /* Find a fallthru edge and emit the goto if necessary. */
2725 FOR_EACH_EDGE (e, ei, bb->succs)
2726 if (e->flags & EDGE_FALLTHRU)
2729 if (!e || e->dest == bb->next_bb)
2732 gcc_assert (e->dest != EXIT_BLOCK_PTR);
2733 label = tree_block_label (e->dest);
2735 stmt = build1 (GOTO_EXPR, void_type_node, label);
2736 #ifdef USE_MAPPED_LOCATION
2737 SET_EXPR_LOCATION (stmt, e->goto_locus);
2739 SET_EXPR_LOCUS (stmt, e->goto_locus);
2741 bsi_insert_after (&last, stmt, BSI_NEW_STMT);
2742 e->flags &= ~EDGE_FALLTHRU;
2746 /* Remove block annotations and other datastructures. */
2749 delete_tree_cfg_annotations (void)
2752 if (n_basic_blocks > 0)
2753 free_blocks_annotations ();
2755 label_to_block_map = NULL;
2762 /* Return the first statement in basic block BB. */
2765 first_stmt (basic_block bb)
2767 block_stmt_iterator i = bsi_start (bb);
2768 return !bsi_end_p (i) ? bsi_stmt (i) : NULL_TREE;
2772 /* Return the last statement in basic block BB. */
2775 last_stmt (basic_block bb)
2777 block_stmt_iterator b = bsi_last (bb);
2778 return !bsi_end_p (b) ? bsi_stmt (b) : NULL_TREE;
2782 /* Return a pointer to the last statement in block BB. */
2785 last_stmt_ptr (basic_block bb)
2787 block_stmt_iterator last = bsi_last (bb);
2788 return !bsi_end_p (last) ? bsi_stmt_ptr (last) : NULL;
2792 /* Return the last statement of an otherwise empty block. Return NULL
2793 if the block is totally empty, or if it contains more than one
2797 last_and_only_stmt (basic_block bb)
2799 block_stmt_iterator i = bsi_last (bb);
2805 last = bsi_stmt (i);
2810 /* Empty statements should no longer appear in the instruction stream.
2811 Everything that might have appeared before should be deleted by
2812 remove_useless_stmts, and the optimizers should just bsi_remove
2813 instead of smashing with build_empty_stmt.
2815 Thus the only thing that should appear here in a block containing
2816 one executable statement is a label. */
2817 prev = bsi_stmt (i);
2818 if (TREE_CODE (prev) == LABEL_EXPR)
2825 /* Mark BB as the basic block holding statement T. */
2828 set_bb_for_stmt (tree t, basic_block bb)
2830 if (TREE_CODE (t) == PHI_NODE)
2832 else if (TREE_CODE (t) == STATEMENT_LIST)
2834 tree_stmt_iterator i;
2835 for (i = tsi_start (t); !tsi_end_p (i); tsi_next (&i))
2836 set_bb_for_stmt (tsi_stmt (i), bb);
2840 stmt_ann_t ann = get_stmt_ann (t);
2843 /* If the statement is a label, add the label to block-to-labels map
2844 so that we can speed up edge creation for GOTO_EXPRs. */
2845 if (TREE_CODE (t) == LABEL_EXPR)
2849 t = LABEL_EXPR_LABEL (t);
2850 uid = LABEL_DECL_UID (t);
2853 LABEL_DECL_UID (t) = uid = cfun->last_label_uid++;
2854 if (VARRAY_SIZE (label_to_block_map) <= (unsigned) uid)
2855 VARRAY_GROW (label_to_block_map, 3 * uid / 2);
2858 /* We're moving an existing label. Make sure that we've
2859 removed it from the old block. */
2860 gcc_assert (!bb || !VARRAY_BB (label_to_block_map, uid));
2861 VARRAY_BB (label_to_block_map, uid) = bb;
2866 /* Finds iterator for STMT. */
2868 extern block_stmt_iterator
2869 bsi_for_stmt (tree stmt)
2871 block_stmt_iterator bsi;
2873 for (bsi = bsi_start (bb_for_stmt (stmt)); !bsi_end_p (bsi); bsi_next (&bsi))
2874 if (bsi_stmt (bsi) == stmt)
2880 /* Insert statement (or statement list) T before the statement
2881 pointed-to by iterator I. M specifies how to update iterator I
2882 after insertion (see enum bsi_iterator_update). */
2885 bsi_insert_before (block_stmt_iterator *i, tree t, enum bsi_iterator_update m)
2887 set_bb_for_stmt (t, i->bb);
2888 tsi_link_before (&i->tsi, t, m);
2893 /* Insert statement (or statement list) T after the statement
2894 pointed-to by iterator I. M specifies how to update iterator I
2895 after insertion (see enum bsi_iterator_update). */
2898 bsi_insert_after (block_stmt_iterator *i, tree t, enum bsi_iterator_update m)
2900 set_bb_for_stmt (t, i->bb);
2901 tsi_link_after (&i->tsi, t, m);
2906 /* Remove the statement pointed to by iterator I. The iterator is updated
2907 to the next statement. */
2910 bsi_remove (block_stmt_iterator *i)
2912 tree t = bsi_stmt (*i);
2913 set_bb_for_stmt (t, NULL);
2914 tsi_delink (&i->tsi);
2918 /* Move the statement at FROM so it comes right after the statement at TO. */
2921 bsi_move_after (block_stmt_iterator *from, block_stmt_iterator *to)
2923 tree stmt = bsi_stmt (*from);
2925 bsi_insert_after (to, stmt, BSI_SAME_STMT);
2929 /* Move the statement at FROM so it comes right before the statement at TO. */
2932 bsi_move_before (block_stmt_iterator *from, block_stmt_iterator *to)
2934 tree stmt = bsi_stmt (*from);
2936 bsi_insert_before (to, stmt, BSI_SAME_STMT);
2940 /* Move the statement at FROM to the end of basic block BB. */
2943 bsi_move_to_bb_end (block_stmt_iterator *from, basic_block bb)
2945 block_stmt_iterator last = bsi_last (bb);
2947 /* Have to check bsi_end_p because it could be an empty block. */
2948 if (!bsi_end_p (last) && is_ctrl_stmt (bsi_stmt (last)))
2949 bsi_move_before (from, &last);
2951 bsi_move_after (from, &last);
2955 /* Replace the contents of the statement pointed to by iterator BSI
2956 with STMT. If PRESERVE_EH_INFO is true, the exception handling
2957 information of the original statement is preserved. */
2960 bsi_replace (const block_stmt_iterator *bsi, tree stmt, bool preserve_eh_info)
2963 tree orig_stmt = bsi_stmt (*bsi);
2965 SET_EXPR_LOCUS (stmt, EXPR_LOCUS (orig_stmt));
2966 set_bb_for_stmt (stmt, bsi->bb);
2968 /* Preserve EH region information from the original statement, if
2969 requested by the caller. */
2970 if (preserve_eh_info)
2972 eh_region = lookup_stmt_eh_region (orig_stmt);
2974 add_stmt_to_eh_region (stmt, eh_region);
2977 *bsi_stmt_ptr (*bsi) = stmt;
2982 /* Insert the statement pointed-to by BSI into edge E. Every attempt
2983 is made to place the statement in an existing basic block, but
2984 sometimes that isn't possible. When it isn't possible, the edge is
2985 split and the statement is added to the new block.
2987 In all cases, the returned *BSI points to the correct location. The
2988 return value is true if insertion should be done after the location,
2989 or false if it should be done before the location. If new basic block
2990 has to be created, it is stored in *NEW_BB. */
2993 tree_find_edge_insert_loc (edge e, block_stmt_iterator *bsi,
2994 basic_block *new_bb)
2996 basic_block dest, src;
3002 /* If the destination has one predecessor which has no PHI nodes,
3003 insert there. Except for the exit block.
3005 The requirement for no PHI nodes could be relaxed. Basically we
3006 would have to examine the PHIs to prove that none of them used
3007 the value set by the statement we want to insert on E. That
3008 hardly seems worth the effort. */
3009 if (EDGE_COUNT (dest->preds) == 1
3010 && ! phi_nodes (dest)
3011 && dest != EXIT_BLOCK_PTR)
3013 *bsi = bsi_start (dest);
3014 if (bsi_end_p (*bsi))
3017 /* Make sure we insert after any leading labels. */
3018 tmp = bsi_stmt (*bsi);
3019 while (TREE_CODE (tmp) == LABEL_EXPR)
3022 if (bsi_end_p (*bsi))
3024 tmp = bsi_stmt (*bsi);
3027 if (bsi_end_p (*bsi))
3029 *bsi = bsi_last (dest);
3036 /* If the source has one successor, the edge is not abnormal and
3037 the last statement does not end a basic block, insert there.
3038 Except for the entry block. */
3040 if ((e->flags & EDGE_ABNORMAL) == 0
3041 && EDGE_COUNT (src->succs) == 1
3042 && src != ENTRY_BLOCK_PTR)
3044 *bsi = bsi_last (src);
3045 if (bsi_end_p (*bsi))
3048 tmp = bsi_stmt (*bsi);
3049 if (!stmt_ends_bb_p (tmp))
3052 /* Insert code just before returning the value. We may need to decompose
3053 the return in the case it contains non-trivial operand. */
3054 if (TREE_CODE (tmp) == RETURN_EXPR)
3056 tree op = TREE_OPERAND (tmp, 0);
3057 if (!is_gimple_val (op))
3059 gcc_assert (TREE_CODE (op) == MODIFY_EXPR);
3060 bsi_insert_before (bsi, op, BSI_NEW_STMT);
3061 TREE_OPERAND (tmp, 0) = TREE_OPERAND (op, 0);
3068 /* Otherwise, create a new basic block, and split this edge. */
3069 dest = split_edge (e);
3072 e = EDGE_PRED (dest, 0);
3077 /* This routine will commit all pending edge insertions, creating any new
3078 basic blocks which are necessary. */
3081 bsi_commit_edge_inserts (void)
3087 bsi_commit_one_edge_insert (EDGE_SUCC (ENTRY_BLOCK_PTR, 0), NULL);
3090 FOR_EACH_EDGE (e, ei, bb->succs)
3091 bsi_commit_one_edge_insert (e, NULL);
3095 /* Commit insertions pending at edge E. If a new block is created, set NEW_BB
3096 to this block, otherwise set it to NULL. */
3099 bsi_commit_one_edge_insert (edge e, basic_block *new_bb)
3103 if (PENDING_STMT (e))
3105 block_stmt_iterator bsi;
3106 tree stmt = PENDING_STMT (e);
3108 PENDING_STMT (e) = NULL_TREE;
3110 if (tree_find_edge_insert_loc (e, &bsi, new_bb))
3111 bsi_insert_after (&bsi, stmt, BSI_NEW_STMT);
3113 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
3118 /* Add STMT to the pending list of edge E. No actual insertion is
3119 made until a call to bsi_commit_edge_inserts () is made. */
3122 bsi_insert_on_edge (edge e, tree stmt)
3124 append_to_statement_list (stmt, &PENDING_STMT (e));
3127 /* Similar to bsi_insert_on_edge+bsi_commit_edge_inserts. If a new
3128 block has to be created, it is returned. */
3131 bsi_insert_on_edge_immediate (edge e, tree stmt)
3133 block_stmt_iterator bsi;
3134 basic_block new_bb = NULL;
3136 gcc_assert (!PENDING_STMT (e));
3138 if (tree_find_edge_insert_loc (e, &bsi, &new_bb))
3139 bsi_insert_after (&bsi, stmt, BSI_NEW_STMT);
3141 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
3146 /*---------------------------------------------------------------------------
3147 Tree specific functions for CFG manipulation
3148 ---------------------------------------------------------------------------*/
3150 /* Reinstall those PHI arguments queued in OLD_EDGE to NEW_EDGE. */
3153 reinstall_phi_args (edge new_edge, edge old_edge)
3157 if (!PENDING_STMT (old_edge))
3160 for (var = PENDING_STMT (old_edge), phi = phi_nodes (new_edge->dest);
3162 var = TREE_CHAIN (var), phi = PHI_CHAIN (phi))
3164 tree result = TREE_PURPOSE (var);
3165 tree arg = TREE_VALUE (var);
3167 gcc_assert (result == PHI_RESULT (phi));
3169 add_phi_arg (phi, arg, new_edge);
3172 PENDING_STMT (old_edge) = NULL;
3175 /* Split a (typically critical) edge EDGE_IN. Return the new block.
3176 Abort on abnormal edges. */
3179 tree_split_edge (edge edge_in)
3181 basic_block new_bb, after_bb, dest, src;
3184 /* Abnormal edges cannot be split. */
3185 gcc_assert (!(edge_in->flags & EDGE_ABNORMAL));
3188 dest = edge_in->dest;
3190 /* Place the new block in the block list. Try to keep the new block
3191 near its "logical" location. This is of most help to humans looking
3192 at debugging dumps. */
3193 if (dest->prev_bb && find_edge (dest->prev_bb, dest))
3194 after_bb = edge_in->src;
3196 after_bb = dest->prev_bb;
3198 new_bb = create_empty_bb (after_bb);
3199 new_bb->frequency = EDGE_FREQUENCY (edge_in);
3200 new_bb->count = edge_in->count;
3201 new_edge = make_edge (new_bb, dest, EDGE_FALLTHRU);
3202 new_edge->probability = REG_BR_PROB_BASE;
3203 new_edge->count = edge_in->count;
3205 e = redirect_edge_and_branch (edge_in, new_bb);
3207 reinstall_phi_args (new_edge, e);
3213 /* Return true when BB has label LABEL in it. */
3216 has_label_p (basic_block bb, tree label)
3218 block_stmt_iterator bsi;
3220 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3222 tree stmt = bsi_stmt (bsi);
3224 if (TREE_CODE (stmt) != LABEL_EXPR)
3226 if (LABEL_EXPR_LABEL (stmt) == label)
3233 /* Callback for walk_tree, check that all elements with address taken are
3234 properly noticed as such. The DATA is an int* that is 1 if TP was seen
3235 inside a PHI node. */
3238 verify_expr (tree *tp, int *walk_subtrees, void *data ATTRIBUTE_UNUSED)
3241 bool in_phi = (data != NULL);
3246 /* Check operand N for being valid GIMPLE and give error MSG if not.
3247 We check for constants explicitly since they are not considered
3248 gimple invariants if they overflowed. */
3249 #define CHECK_OP(N, MSG) \
3250 do { if (!CONSTANT_CLASS_P (TREE_OPERAND (t, N)) \
3251 && !is_gimple_val (TREE_OPERAND (t, N))) \
3252 { error (MSG); return TREE_OPERAND (t, N); }} while (0)
3254 switch (TREE_CODE (t))
3257 if (SSA_NAME_IN_FREE_LIST (t))
3259 error ("SSA name in freelist but still referenced");
3265 x = TREE_OPERAND (t, 0);
3266 if (TREE_CODE (x) == BIT_FIELD_REF
3267 && is_gimple_reg (TREE_OPERAND (x, 0)))
3269 error ("GIMPLE register modified with BIT_FIELD_REF");
3275 /* ??? tree-ssa-alias.c may have overlooked dead PHI nodes, missing
3276 dead PHIs that take the address of something. But if the PHI
3277 result is dead, the fact that it takes the address of anything
3278 is irrelevant. Because we can not tell from here if a PHI result
3279 is dead, we just skip this check for PHIs altogether. This means
3280 we may be missing "valid" checks, but what can you do?
3281 This was PR19217. */
3285 /* Skip any references (they will be checked when we recurse down the
3286 tree) and ensure that any variable used as a prefix is marked
3288 for (x = TREE_OPERAND (t, 0);
3289 handled_component_p (x);
3290 x = TREE_OPERAND (x, 0))
3293 if (TREE_CODE (x) != VAR_DECL && TREE_CODE (x) != PARM_DECL)
3295 if (!TREE_ADDRESSABLE (x))
3297 error ("address taken, but ADDRESSABLE bit not set");
3303 x = COND_EXPR_COND (t);
3304 if (TREE_CODE (TREE_TYPE (x)) != BOOLEAN_TYPE)
3306 error ("non-boolean used in condition");
3313 case FIX_TRUNC_EXPR:
3315 case FIX_FLOOR_EXPR:
3316 case FIX_ROUND_EXPR:
3321 case NON_LVALUE_EXPR:
3322 case TRUTH_NOT_EXPR:
3323 CHECK_OP (0, "Invalid operand to unary operator");
3330 case ARRAY_RANGE_REF:
3332 case VIEW_CONVERT_EXPR:
3333 /* We have a nest of references. Verify that each of the operands
3334 that determine where to reference is either a constant or a variable,
3335 verify that the base is valid, and then show we've already checked
3337 while (handled_component_p (t))
3339 if (TREE_CODE (t) == COMPONENT_REF && TREE_OPERAND (t, 2))
3340 CHECK_OP (2, "Invalid COMPONENT_REF offset operator");
3341 else if (TREE_CODE (t) == ARRAY_REF
3342 || TREE_CODE (t) == ARRAY_RANGE_REF)
3344 CHECK_OP (1, "Invalid array index.");
3345 if (TREE_OPERAND (t, 2))
3346 CHECK_OP (2, "Invalid array lower bound.");
3347 if (TREE_OPERAND (t, 3))
3348 CHECK_OP (3, "Invalid array stride.");
3350 else if (TREE_CODE (t) == BIT_FIELD_REF)
3352 CHECK_OP (1, "Invalid operand to BIT_FIELD_REF");
3353 CHECK_OP (2, "Invalid operand to BIT_FIELD_REF");
3356 t = TREE_OPERAND (t, 0);
3359 if (!CONSTANT_CLASS_P (t) && !is_gimple_lvalue (t))
3361 error ("Invalid reference prefix.");
3373 case UNORDERED_EXPR:
3384 case TRUNC_DIV_EXPR:
3386 case FLOOR_DIV_EXPR:
3387 case ROUND_DIV_EXPR:
3388 case TRUNC_MOD_EXPR:
3390 case FLOOR_MOD_EXPR:
3391 case ROUND_MOD_EXPR:
3393 case EXACT_DIV_EXPR:
3403 CHECK_OP (0, "Invalid operand to binary operator");
3404 CHECK_OP (1, "Invalid operand to binary operator");
3416 /* Verify STMT, return true if STMT is not in GIMPLE form.
3417 TODO: Implement type checking. */
3420 verify_stmt (tree stmt, bool last_in_block)
3424 if (!is_gimple_stmt (stmt))
3426 error ("Is not a valid GIMPLE statement.");
3430 addr = walk_tree (&stmt, verify_expr, NULL, NULL);
3433 debug_generic_stmt (addr);
3437 /* If the statement is marked as part of an EH region, then it is
3438 expected that the statement could throw. Verify that when we
3439 have optimizations that simplify statements such that we prove
3440 that they cannot throw, that we update other data structures
3442 if (lookup_stmt_eh_region (stmt) >= 0)
3444 if (!tree_could_throw_p (stmt))
3446 error ("Statement marked for throw, but doesn%'t.");
3449 if (!last_in_block && tree_can_throw_internal (stmt))
3451 error ("Statement marked for throw in middle of block.");
3459 debug_generic_stmt (stmt);
3464 /* Return true when the T can be shared. */
3467 tree_node_can_be_shared (tree t)
3469 if (IS_TYPE_OR_DECL_P (t)
3470 /* We check for constants explicitly since they are not considered
3471 gimple invariants if they overflowed. */
3472 || CONSTANT_CLASS_P (t)
3473 || is_gimple_min_invariant (t)
3474 || TREE_CODE (t) == SSA_NAME
3475 || t == error_mark_node)
3478 if (TREE_CODE (t) == CASE_LABEL_EXPR)
3481 while (((TREE_CODE (t) == ARRAY_REF || TREE_CODE (t) == ARRAY_RANGE_REF)
3482 /* We check for constants explicitly since they are not considered
3483 gimple invariants if they overflowed. */
3484 && (CONSTANT_CLASS_P (TREE_OPERAND (t, 1))
3485 || is_gimple_min_invariant (TREE_OPERAND (t, 1))))
3486 || (TREE_CODE (t) == COMPONENT_REF
3487 || TREE_CODE (t) == REALPART_EXPR
3488 || TREE_CODE (t) == IMAGPART_EXPR))
3489 t = TREE_OPERAND (t, 0);
3498 /* Called via walk_trees. Verify tree sharing. */
3501 verify_node_sharing (tree * tp, int *walk_subtrees, void *data)
3503 htab_t htab = (htab_t) data;
3506 if (tree_node_can_be_shared (*tp))
3508 *walk_subtrees = false;
3512 slot = htab_find_slot (htab, *tp, INSERT);
3521 /* Verify the GIMPLE statement chain. */
3527 block_stmt_iterator bsi;
3532 timevar_push (TV_TREE_STMT_VERIFY);
3533 htab = htab_create (37, htab_hash_pointer, htab_eq_pointer, NULL);
3540 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
3542 int phi_num_args = PHI_NUM_ARGS (phi);
3544 for (i = 0; i < phi_num_args; i++)
3546 tree t = PHI_ARG_DEF (phi, i);
3549 /* Addressable variables do have SSA_NAMEs but they
3550 are not considered gimple values. */
3551 if (TREE_CODE (t) != SSA_NAME
3552 && TREE_CODE (t) != FUNCTION_DECL
3553 && !is_gimple_val (t))
3555 error ("PHI def is not a GIMPLE value");
3556 debug_generic_stmt (phi);
3557 debug_generic_stmt (t);
3561 addr = walk_tree (&t, verify_expr, (void *) 1, NULL);
3564 debug_generic_stmt (addr);
3568 addr = walk_tree (&t, verify_node_sharing, htab, NULL);
3571 error ("Incorrect sharing of tree nodes");
3572 debug_generic_stmt (phi);
3573 debug_generic_stmt (addr);
3579 for (bsi = bsi_start (bb); !bsi_end_p (bsi); )
3581 tree stmt = bsi_stmt (bsi);
3583 err |= verify_stmt (stmt, bsi_end_p (bsi));
3584 addr = walk_tree (&stmt, verify_node_sharing, htab, NULL);
3587 error ("Incorrect sharing of tree nodes");
3588 debug_generic_stmt (stmt);
3589 debug_generic_stmt (addr);
3596 internal_error ("verify_stmts failed.");
3599 timevar_pop (TV_TREE_STMT_VERIFY);
3603 /* Verifies that the flow information is OK. */
3606 tree_verify_flow_info (void)
3610 block_stmt_iterator bsi;
3615 if (ENTRY_BLOCK_PTR->stmt_list)
3617 error ("ENTRY_BLOCK has a statement list associated with it\n");
3621 if (EXIT_BLOCK_PTR->stmt_list)
3623 error ("EXIT_BLOCK has a statement list associated with it\n");
3627 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
3628 if (e->flags & EDGE_FALLTHRU)
3630 error ("Fallthru to exit from bb %d\n", e->src->index);
3636 bool found_ctrl_stmt = false;
3640 /* Skip labels on the start of basic block. */
3641 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3643 tree prev_stmt = stmt;
3645 stmt = bsi_stmt (bsi);
3647 if (TREE_CODE (stmt) != LABEL_EXPR)
3650 if (prev_stmt && DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)))
3652 error ("Nonlocal label %s is not first "
3653 "in a sequence of labels in bb %d",
3654 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt))),
3659 if (label_to_block (LABEL_EXPR_LABEL (stmt)) != bb)
3661 error ("Label %s to block does not match in bb %d\n",
3662 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt))),
3667 if (decl_function_context (LABEL_EXPR_LABEL (stmt))
3668 != current_function_decl)
3670 error ("Label %s has incorrect context in bb %d\n",
3671 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt))),
3677 /* Verify that body of basic block BB is free of control flow. */
3678 for (; !bsi_end_p (bsi); bsi_next (&bsi))
3680 tree stmt = bsi_stmt (bsi);
3682 if (found_ctrl_stmt)
3684 error ("Control flow in the middle of basic block %d\n",
3689 if (stmt_ends_bb_p (stmt))
3690 found_ctrl_stmt = true;
3692 if (TREE_CODE (stmt) == LABEL_EXPR)
3694 error ("Label %s in the middle of basic block %d\n",
3695 IDENTIFIER_POINTER (DECL_NAME (stmt)),
3700 bsi = bsi_last (bb);
3701 if (bsi_end_p (bsi))
3704 stmt = bsi_stmt (bsi);
3706 if (is_ctrl_stmt (stmt))
3708 FOR_EACH_EDGE (e, ei, bb->succs)
3709 if (e->flags & EDGE_FALLTHRU)
3711 error ("Fallthru edge after a control statement in bb %d \n",
3717 switch (TREE_CODE (stmt))
3723 if (TREE_CODE (COND_EXPR_THEN (stmt)) != GOTO_EXPR
3724 || TREE_CODE (COND_EXPR_ELSE (stmt)) != GOTO_EXPR)
3726 error ("Structured COND_EXPR at the end of bb %d\n", bb->index);
3730 extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
3732 if (!true_edge || !false_edge
3733 || !(true_edge->flags & EDGE_TRUE_VALUE)
3734 || !(false_edge->flags & EDGE_FALSE_VALUE)
3735 || (true_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL))
3736 || (false_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL))
3737 || EDGE_COUNT (bb->succs) >= 3)
3739 error ("Wrong outgoing edge flags at end of bb %d\n",
3744 if (!has_label_p (true_edge->dest,
3745 GOTO_DESTINATION (COND_EXPR_THEN (stmt))))
3747 error ("%<then%> label does not match edge at end of bb %d\n",
3752 if (!has_label_p (false_edge->dest,
3753 GOTO_DESTINATION (COND_EXPR_ELSE (stmt))))
3755 error ("%<else%> label does not match edge at end of bb %d\n",
3763 if (simple_goto_p (stmt))
3765 error ("Explicit goto at end of bb %d\n", bb->index);
3770 /* FIXME. We should double check that the labels in the
3771 destination blocks have their address taken. */
3772 FOR_EACH_EDGE (e, ei, bb->succs)
3773 if ((e->flags & (EDGE_FALLTHRU | EDGE_TRUE_VALUE
3774 | EDGE_FALSE_VALUE))
3775 || !(e->flags & EDGE_ABNORMAL))
3777 error ("Wrong outgoing edge flags at end of bb %d\n",
3785 if (EDGE_COUNT (bb->succs) != 1
3786 || (EDGE_SUCC (bb, 0)->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL
3787 | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
3789 error ("Wrong outgoing edge flags at end of bb %d\n", bb->index);
3792 if (EDGE_SUCC (bb, 0)->dest != EXIT_BLOCK_PTR)
3794 error ("Return edge does not point to exit in bb %d\n",
3807 vec = SWITCH_LABELS (stmt);
3808 n = TREE_VEC_LENGTH (vec);
3810 /* Mark all the destination basic blocks. */
3811 for (i = 0; i < n; ++i)
3813 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
3814 basic_block label_bb = label_to_block (lab);
3816 gcc_assert (!label_bb->aux || label_bb->aux == (void *)1);
3817 label_bb->aux = (void *)1;
3820 /* Verify that the case labels are sorted. */
3821 prev = TREE_VEC_ELT (vec, 0);
3822 for (i = 1; i < n - 1; ++i)
3824 tree c = TREE_VEC_ELT (vec, i);
3827 error ("Found default case not at end of case vector");
3831 if (! tree_int_cst_lt (CASE_LOW (prev), CASE_LOW (c)))
3833 error ("Case labels not sorted:\n ");
3834 print_generic_expr (stderr, prev, 0);
3835 fprintf (stderr," is greater than ");
3836 print_generic_expr (stderr, c, 0);
3837 fprintf (stderr," but comes before it.\n");
3842 if (CASE_LOW (TREE_VEC_ELT (vec, n - 1)))
3844 error ("No default case found at end of case vector");
3848 FOR_EACH_EDGE (e, ei, bb->succs)
3852 error ("Extra outgoing edge %d->%d\n",
3853 bb->index, e->dest->index);
3856 e->dest->aux = (void *)2;
3857 if ((e->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL
3858 | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
3860 error ("Wrong outgoing edge flags at end of bb %d\n",
3866 /* Check that we have all of them. */
3867 for (i = 0; i < n; ++i)
3869 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
3870 basic_block label_bb = label_to_block (lab);
3872 if (label_bb->aux != (void *)2)
3874 error ("Missing edge %i->%i",
3875 bb->index, label_bb->index);
3880 FOR_EACH_EDGE (e, ei, bb->succs)
3881 e->dest->aux = (void *)0;
3888 if (dom_computed[CDI_DOMINATORS] >= DOM_NO_FAST_QUERY)
3889 verify_dominators (CDI_DOMINATORS);
3895 /* Updates phi nodes after creating a forwarder block joined
3896 by edge FALLTHRU. */
3899 tree_make_forwarder_block (edge fallthru)
3903 basic_block dummy, bb;
3904 tree phi, new_phi, var;
3906 dummy = fallthru->src;
3907 bb = fallthru->dest;
3909 if (EDGE_COUNT (bb->preds) == 1)
3912 /* If we redirected a branch we must create new phi nodes at the
3914 for (phi = phi_nodes (dummy); phi; phi = PHI_CHAIN (phi))
3916 var = PHI_RESULT (phi);
3917 new_phi = create_phi_node (var, bb);
3918 SSA_NAME_DEF_STMT (var) = new_phi;
3919 SET_PHI_RESULT (phi, make_ssa_name (SSA_NAME_VAR (var), phi));
3920 add_phi_arg (new_phi, PHI_RESULT (phi), fallthru);
3923 /* Ensure that the PHI node chain is in the same order. */
3924 set_phi_nodes (bb, phi_reverse (phi_nodes (bb)));
3926 /* Add the arguments we have stored on edges. */
3927 FOR_EACH_EDGE (e, ei, bb->preds)
3932 flush_pending_stmts (e);
3937 /* Return true if basic block BB does nothing except pass control
3938 flow to another block and that we can safely insert a label at
3939 the start of the successor block.
3941 As a precondition, we require that BB be not equal to
3945 tree_forwarder_block_p (basic_block bb, bool phi_wanted)
3947 block_stmt_iterator bsi;
3949 /* BB must have a single outgoing edge. */
3950 if (EDGE_COUNT (bb->succs) != 1
3951 /* If PHI_WANTED is false, BB must not have any PHI nodes.
3952 Otherwise, BB must have PHI nodes. */
3953 || (phi_nodes (bb) != NULL_TREE) != phi_wanted
3954 /* BB may not be a predecessor of EXIT_BLOCK_PTR. */
3955 || EDGE_SUCC (bb, 0)->dest == EXIT_BLOCK_PTR
3956 /* Nor should this be an infinite loop. */
3957 || EDGE_SUCC (bb, 0)->dest == bb
3958 /* BB may not have an abnormal outgoing edge. */
3959 || (EDGE_SUCC (bb, 0)->flags & EDGE_ABNORMAL))
3963 gcc_assert (bb != ENTRY_BLOCK_PTR);
3966 /* Now walk through the statements backward. We can ignore labels,
3967 anything else means this is not a forwarder block. */
3968 for (bsi = bsi_last (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3970 tree stmt = bsi_stmt (bsi);
3972 switch (TREE_CODE (stmt))
3975 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)))
3984 if (find_edge (ENTRY_BLOCK_PTR, bb))
3990 /* Return true if BB has at least one abnormal incoming edge. */
3993 has_abnormal_incoming_edge_p (basic_block bb)
3998 FOR_EACH_EDGE (e, ei, bb->preds)
3999 if (e->flags & EDGE_ABNORMAL)
4005 /* Removes forwarder block BB. Returns false if this failed. If a new
4006 forwarder block is created due to redirection of edges, it is
4007 stored to worklist. */
4010 remove_forwarder_block (basic_block bb, basic_block **worklist)
4012 edge succ = EDGE_SUCC (bb, 0), e, s;
4013 basic_block dest = succ->dest;
4017 block_stmt_iterator bsi, bsi_to;
4018 bool seen_abnormal_edge = false;
4020 /* We check for infinite loops already in tree_forwarder_block_p.
4021 However it may happen that the infinite loop is created
4022 afterwards due to removal of forwarders. */
4026 /* If the destination block consists of a nonlocal label, do not merge
4028 label = first_stmt (dest);
4030 && TREE_CODE (label) == LABEL_EXPR
4031 && DECL_NONLOCAL (LABEL_EXPR_LABEL (label)))
4034 /* If there is an abnormal edge to basic block BB, but not into
4035 dest, problems might occur during removal of the phi node at out
4036 of ssa due to overlapping live ranges of registers.
4038 If there is an abnormal edge in DEST, the problems would occur
4039 anyway since cleanup_dead_labels would then merge the labels for
4040 two different eh regions, and rest of exception handling code
4043 So if there is an abnormal edge to BB, proceed only if there is
4044 no abnormal edge to DEST and there are no phi nodes in DEST. */
4045 if (has_abnormal_incoming_edge_p (bb))
4047 seen_abnormal_edge = true;
4049 if (has_abnormal_incoming_edge_p (dest)
4050 || phi_nodes (dest) != NULL_TREE)
4054 /* If there are phi nodes in DEST, and some of the blocks that are
4055 predecessors of BB are also predecessors of DEST, check that the
4056 phi node arguments match. */
4057 if (phi_nodes (dest))
4059 FOR_EACH_EDGE (e, ei, bb->preds)
4061 s = find_edge (e->src, dest);
4065 if (!phi_alternatives_equal (dest, succ, s))
4070 /* Redirect the edges. */
4071 for (ei = ei_start (bb->preds); (e = ei_safe_edge (ei)); )
4073 if (e->flags & EDGE_ABNORMAL)
4075 /* If there is an abnormal edge, redirect it anyway, and
4076 move the labels to the new block to make it legal. */
4077 s = redirect_edge_succ_nodup (e, dest);
4080 s = redirect_edge_and_branch (e, dest);
4084 /* Create arguments for the phi nodes, since the edge was not
4086 for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi))
4087 add_phi_arg (phi, PHI_ARG_DEF (phi, succ->dest_idx), s);
4091 /* The source basic block might become a forwarder. We know
4092 that it was not a forwarder before, since it used to have
4093 at least two outgoing edges, so we may just add it to
4095 if (tree_forwarder_block_p (s->src, false))
4096 *(*worklist)++ = s->src;
4100 if (seen_abnormal_edge)
4102 /* Move the labels to the new block, so that the redirection of
4103 the abnormal edges works. */
4105 bsi_to = bsi_start (dest);
4106 for (bsi = bsi_start (bb); !bsi_end_p (bsi); )
4108 label = bsi_stmt (bsi);
4109 gcc_assert (TREE_CODE (label) == LABEL_EXPR);
4111 bsi_insert_before (&bsi_to, label, BSI_CONTINUE_LINKING);
4115 /* Update the dominators. */
4116 if (dom_info_available_p (CDI_DOMINATORS))
4118 basic_block dom, dombb, domdest;
4120 dombb = get_immediate_dominator (CDI_DOMINATORS, bb);
4121 domdest = get_immediate_dominator (CDI_DOMINATORS, dest);
4124 /* Shortcut to avoid calling (relatively expensive)
4125 nearest_common_dominator unless necessary. */
4129 dom = nearest_common_dominator (CDI_DOMINATORS, domdest, dombb);
4131 set_immediate_dominator (CDI_DOMINATORS, dest, dom);
4134 /* And kill the forwarder block. */
4135 delete_basic_block (bb);
4140 /* Removes forwarder blocks. */
4143 cleanup_forwarder_blocks (void)
4146 bool changed = false;
4147 basic_block *worklist = xmalloc (sizeof (basic_block) * n_basic_blocks);
4148 basic_block *current = worklist;
4152 if (tree_forwarder_block_p (bb, false))
4156 while (current != worklist)
4159 changed |= remove_forwarder_block (bb, ¤t);
4166 /* Merge the PHI nodes at BB into those at BB's sole successor. */
4169 remove_forwarder_block_with_phi (basic_block bb)
4171 edge succ = EDGE_SUCC (bb, 0);
4172 basic_block dest = succ->dest;
4174 basic_block dombb, domdest, dom;
4176 /* We check for infinite loops already in tree_forwarder_block_p.
4177 However it may happen that the infinite loop is created
4178 afterwards due to removal of forwarders. */
4182 /* If the destination block consists of a nonlocal label, do not
4184 label = first_stmt (dest);
4186 && TREE_CODE (label) == LABEL_EXPR
4187 && DECL_NONLOCAL (LABEL_EXPR_LABEL (label)))
4190 /* Redirect each incoming edge to BB to DEST. */
4191 while (EDGE_COUNT (bb->preds) > 0)
4193 edge e = EDGE_PRED (bb, 0), s;
4196 s = find_edge (e->src, dest);
4199 /* We already have an edge S from E->src to DEST. If S and
4200 E->dest's sole successor edge have the same PHI arguments
4201 at DEST, redirect S to DEST. */
4202 if (phi_alternatives_equal (dest, s, succ))
4204 e = redirect_edge_and_branch (e, dest);
4205 PENDING_STMT (e) = NULL_TREE;
4209 /* PHI arguments are different. Create a forwarder block by
4210 splitting E so that we can merge PHI arguments on E to
4212 e = EDGE_SUCC (split_edge (e), 0);
4215 s = redirect_edge_and_branch (e, dest);
4217 /* redirect_edge_and_branch must not create a new edge. */
4218 gcc_assert (s == e);
4220 /* Add to the PHI nodes at DEST each PHI argument removed at the
4221 destination of E. */
4222 for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi))
4224 tree def = PHI_ARG_DEF (phi, succ->dest_idx);
4226 if (TREE_CODE (def) == SSA_NAME)
4230 /* If DEF is one of the results of PHI nodes removed during
4231 redirection, replace it with the PHI argument that used
4233 for (var = PENDING_STMT (e); var; var = TREE_CHAIN (var))
4235 tree old_arg = TREE_PURPOSE (var);
4236 tree new_arg = TREE_VALUE (var);
4246 add_phi_arg (phi, def, s);
4249 PENDING_STMT (e) = NULL;
4252 /* Update the dominators. */
4253 dombb = get_immediate_dominator (CDI_DOMINATORS, bb);
4254 domdest = get_immediate_dominator (CDI_DOMINATORS, dest);
4257 /* Shortcut to avoid calling (relatively expensive)
4258 nearest_common_dominator unless necessary. */
4262 dom = nearest_common_dominator (CDI_DOMINATORS, domdest, dombb);
4264 set_immediate_dominator (CDI_DOMINATORS, dest, dom);
4266 /* Remove BB since all of BB's incoming edges have been redirected
4268 delete_basic_block (bb);
4271 /* This pass merges PHI nodes if one feeds into another. For example,
4272 suppose we have the following:
4279 # tem_6 = PHI <tem_17(8), tem_23(7)>;
4282 # tem_3 = PHI <tem_6(9), tem_2(5)>;
4285 Then we merge the first PHI node into the second one like so:
4287 goto <bb 9> (<L10>);
4292 # tem_3 = PHI <tem_23(7), tem_2(5), tem_17(8)>;
4297 merge_phi_nodes (void)
4299 basic_block *worklist = xmalloc (sizeof (basic_block) * n_basic_blocks);
4300 basic_block *current = worklist;
4303 calculate_dominance_info (CDI_DOMINATORS);
4305 /* Find all PHI nodes that we may be able to merge. */
4310 /* Look for a forwarder block with PHI nodes. */
4311 if (!tree_forwarder_block_p (bb, true))
4314 dest = EDGE_SUCC (bb, 0)->dest;
4316 /* We have to feed into another basic block with PHI
4318 if (!phi_nodes (dest)
4319 /* We don't want to deal with a basic block with
4321 || has_abnormal_incoming_edge_p (bb))
4324 if (!dominated_by_p (CDI_DOMINATORS, dest, bb))
4326 /* If BB does not dominate DEST, then the PHI nodes at
4327 DEST must be the only users of the results of the PHI
4333 /* Now let's drain WORKLIST. */
4334 while (current != worklist)
4337 remove_forwarder_block_with_phi (bb);
4344 gate_merge_phi (void)
4349 struct tree_opt_pass pass_merge_phi = {
4350 "mergephi", /* name */
4351 gate_merge_phi, /* gate */
4352 merge_phi_nodes, /* execute */
4355 0, /* static_pass_number */
4356 TV_TREE_MERGE_PHI, /* tv_id */
4357 PROP_cfg | PROP_ssa, /* properties_required */
4358 0, /* properties_provided */
4359 0, /* properties_destroyed */
4360 0, /* todo_flags_start */
4361 TODO_dump_func | TODO_ggc_collect /* todo_flags_finish */
4366 /* Return a non-special label in the head of basic block BLOCK.
4367 Create one if it doesn't exist. */
4370 tree_block_label (basic_block bb)
4372 block_stmt_iterator i, s = bsi_start (bb);
4376 for (i = s; !bsi_end_p (i); first = false, bsi_next (&i))
4378 stmt = bsi_stmt (i);
4379 if (TREE_CODE (stmt) != LABEL_EXPR)
4381 label = LABEL_EXPR_LABEL (stmt);
4382 if (!DECL_NONLOCAL (label))
4385 bsi_move_before (&i, &s);
4390 label = create_artificial_label ();
4391 stmt = build1 (LABEL_EXPR, void_type_node, label);
4392 bsi_insert_before (&s, stmt, BSI_NEW_STMT);
4397 /* Attempt to perform edge redirection by replacing a possibly complex
4398 jump instruction by a goto or by removing the jump completely.
4399 This can apply only if all edges now point to the same block. The
4400 parameters and return values are equivalent to
4401 redirect_edge_and_branch. */
4404 tree_try_redirect_by_replacing_jump (edge e, basic_block target)
4406 basic_block src = e->src;
4407 block_stmt_iterator b;
4410 /* We can replace or remove a complex jump only when we have exactly
4412 if (EDGE_COUNT (src->succs) != 2
4413 /* Verify that all targets will be TARGET. Specifically, the
4414 edge that is not E must also go to TARGET. */
4415 || EDGE_SUCC (src, EDGE_SUCC (src, 0) == e)->dest != target)
4421 stmt = bsi_stmt (b);
4423 if (TREE_CODE (stmt) == COND_EXPR
4424 || TREE_CODE (stmt) == SWITCH_EXPR)
4427 e = ssa_redirect_edge (e, target);
4428 e->flags = EDGE_FALLTHRU;
4436 /* Redirect E to DEST. Return NULL on failure. Otherwise, return the
4437 edge representing the redirected branch. */
4440 tree_redirect_edge_and_branch (edge e, basic_block dest)
4442 basic_block bb = e->src;
4443 block_stmt_iterator bsi;
4447 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
4450 if (e->src != ENTRY_BLOCK_PTR
4451 && (ret = tree_try_redirect_by_replacing_jump (e, dest)))
4454 if (e->dest == dest)
4457 label = tree_block_label (dest);
4459 bsi = bsi_last (bb);
4460 stmt = bsi_end_p (bsi) ? NULL : bsi_stmt (bsi);
4462 switch (stmt ? TREE_CODE (stmt) : ERROR_MARK)
4465 stmt = (e->flags & EDGE_TRUE_VALUE
4466 ? COND_EXPR_THEN (stmt)
4467 : COND_EXPR_ELSE (stmt));
4468 GOTO_DESTINATION (stmt) = label;
4472 /* No non-abnormal edges should lead from a non-simple goto, and
4473 simple ones should be represented implicitly. */
4478 tree cases = get_cases_for_edge (e, stmt);
4480 /* If we have a list of cases associated with E, then use it
4481 as it's a lot faster than walking the entire case vector. */
4484 edge e2 = find_edge (e->src, dest);
4491 CASE_LABEL (cases) = label;
4492 cases = TREE_CHAIN (cases);
4495 /* If there was already an edge in the CFG, then we need
4496 to move all the cases associated with E to E2. */
4499 tree cases2 = get_cases_for_edge (e2, stmt);
4501 TREE_CHAIN (last) = TREE_CHAIN (cases2);
4502 TREE_CHAIN (cases2) = first;
4507 tree vec = SWITCH_LABELS (stmt);
4508 size_t i, n = TREE_VEC_LENGTH (vec);
4510 for (i = 0; i < n; i++)
4512 tree elt = TREE_VEC_ELT (vec, i);
4514 if (label_to_block (CASE_LABEL (elt)) == e->dest)
4515 CASE_LABEL (elt) = label;
4524 e->flags |= EDGE_FALLTHRU;
4528 /* Otherwise it must be a fallthru edge, and we don't need to
4529 do anything besides redirecting it. */
4530 gcc_assert (e->flags & EDGE_FALLTHRU);
4534 /* Update/insert PHI nodes as necessary. */
4536 /* Now update the edges in the CFG. */
4537 e = ssa_redirect_edge (e, dest);
4543 /* Simple wrapper, as we can always redirect fallthru edges. */
4546 tree_redirect_edge_and_branch_force (edge e, basic_block dest)
4548 e = tree_redirect_edge_and_branch (e, dest);
4555 /* Splits basic block BB after statement STMT (but at least after the
4556 labels). If STMT is NULL, BB is split just after the labels. */
4559 tree_split_block (basic_block bb, void *stmt)
4561 block_stmt_iterator bsi, bsi_tgt;
4567 new_bb = create_empty_bb (bb);
4569 /* Redirect the outgoing edges. */
4570 new_bb->succs = bb->succs;
4572 FOR_EACH_EDGE (e, ei, new_bb->succs)
4575 if (stmt && TREE_CODE ((tree) stmt) == LABEL_EXPR)
4578 /* Move everything from BSI to the new basic block. */
4579 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4581 act = bsi_stmt (bsi);
4582 if (TREE_CODE (act) == LABEL_EXPR)
4595 bsi_tgt = bsi_start (new_bb);
4596 while (!bsi_end_p (bsi))
4598 act = bsi_stmt (bsi);
4600 bsi_insert_after (&bsi_tgt, act, BSI_NEW_STMT);
4607 /* Moves basic block BB after block AFTER. */
4610 tree_move_block_after (basic_block bb, basic_block after)
4612 if (bb->prev_bb == after)
4616 link_block (bb, after);
4622 /* Return true if basic_block can be duplicated. */
4625 tree_can_duplicate_bb_p (basic_block bb ATTRIBUTE_UNUSED)
4630 /* Create a duplicate of the basic block BB. NOTE: This does not
4631 preserve SSA form. */
4634 tree_duplicate_bb (basic_block bb)
4637 block_stmt_iterator bsi, bsi_tgt;
4639 ssa_op_iter op_iter;
4641 new_bb = create_empty_bb (EXIT_BLOCK_PTR->prev_bb);
4643 /* First copy the phi nodes. We do not copy phi node arguments here,
4644 since the edges are not ready yet. Keep the chain of phi nodes in
4645 the same order, so that we can add them later. */
4646 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
4648 mark_for_rewrite (PHI_RESULT (phi));
4649 create_phi_node (PHI_RESULT (phi), new_bb);
4651 set_phi_nodes (new_bb, phi_reverse (phi_nodes (new_bb)));
4653 bsi_tgt = bsi_start (new_bb);
4654 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4656 tree stmt = bsi_stmt (bsi);
4659 if (TREE_CODE (stmt) == LABEL_EXPR)
4662 /* Record the definitions. */
4663 get_stmt_operands (stmt);
4665 FOR_EACH_SSA_TREE_OPERAND (val, stmt, op_iter, SSA_OP_ALL_DEFS)
4666 mark_for_rewrite (val);
4668 copy = unshare_expr (stmt);
4670 /* Copy also the virtual operands. */
4671 get_stmt_ann (copy);
4672 copy_virtual_operands (copy, stmt);
4674 bsi_insert_after (&bsi_tgt, copy, BSI_NEW_STMT);
4680 /* Basic block BB_COPY was created by code duplication. Add phi node
4681 arguments for edges going out of BB_COPY. The blocks that were
4682 duplicated have rbi->duplicated set to one. */
4685 add_phi_args_after_copy_bb (basic_block bb_copy)
4687 basic_block bb, dest;
4690 tree phi, phi_copy, phi_next, def;
4692 bb = bb_copy->rbi->original;
4694 FOR_EACH_EDGE (e_copy, ei, bb_copy->succs)
4696 if (!phi_nodes (e_copy->dest))
4699 if (e_copy->dest->rbi->duplicated)
4700 dest = e_copy->dest->rbi->original;
4702 dest = e_copy->dest;
4704 e = find_edge (bb, dest);
4707 /* During loop unrolling the target of the latch edge is copied.
4708 In this case we are not looking for edge to dest, but to
4709 duplicated block whose original was dest. */
4710 FOR_EACH_EDGE (e, ei, bb->succs)
4711 if (e->dest->rbi->duplicated
4712 && e->dest->rbi->original == dest)
4715 gcc_assert (e != NULL);
4718 for (phi = phi_nodes (e->dest), phi_copy = phi_nodes (e_copy->dest);
4720 phi = phi_next, phi_copy = PHI_CHAIN (phi_copy))
4722 phi_next = PHI_CHAIN (phi);
4724 gcc_assert (PHI_RESULT (phi) == PHI_RESULT (phi_copy));
4725 def = PHI_ARG_DEF_FROM_EDGE (phi, e);
4726 add_phi_arg (phi_copy, def, e_copy);
4731 /* Blocks in REGION_COPY array of length N_REGION were created by
4732 duplication of basic blocks. Add phi node arguments for edges
4733 going from these blocks. */
4736 add_phi_args_after_copy (basic_block *region_copy, unsigned n_region)
4740 for (i = 0; i < n_region; i++)
4741 region_copy[i]->rbi->duplicated = 1;
4743 for (i = 0; i < n_region; i++)
4744 add_phi_args_after_copy_bb (region_copy[i]);
4746 for (i = 0; i < n_region; i++)
4747 region_copy[i]->rbi->duplicated = 0;
4750 /* Maps the old ssa name FROM_NAME to TO_NAME. */
4752 struct ssa_name_map_entry
4758 /* Hash function for ssa_name_map_entry. */
4761 ssa_name_map_entry_hash (const void *entry)
4763 const struct ssa_name_map_entry *en = entry;
4764 return SSA_NAME_VERSION (en->from_name);
4767 /* Equality function for ssa_name_map_entry. */
4770 ssa_name_map_entry_eq (const void *in_table, const void *ssa_name)
4772 const struct ssa_name_map_entry *en = in_table;
4774 return en->from_name == ssa_name;
4777 /* Allocate duplicates of ssa names in list DEFINITIONS and store the mapping
4781 allocate_ssa_names (bitmap definitions, htab_t *map)
4784 struct ssa_name_map_entry *entry;
4790 *map = htab_create (10, ssa_name_map_entry_hash,
4791 ssa_name_map_entry_eq, free);
4792 EXECUTE_IF_SET_IN_BITMAP (definitions, 0, ver, bi)
4794 name = ssa_name (ver);
4795 slot = htab_find_slot_with_hash (*map, name, SSA_NAME_VERSION (name),
4801 entry = xmalloc (sizeof (struct ssa_name_map_entry));
4802 entry->from_name = name;
4805 entry->to_name = duplicate_ssa_name (name, SSA_NAME_DEF_STMT (name));
4809 /* Rewrite the definition DEF in statement STMT to new ssa name as specified
4810 by the mapping MAP. */
4813 rewrite_to_new_ssa_names_def (def_operand_p def, tree stmt, htab_t map)
4815 tree name = DEF_FROM_PTR (def);
4816 struct ssa_name_map_entry *entry;
4818 gcc_assert (TREE_CODE (name) == SSA_NAME);
4820 entry = htab_find_with_hash (map, name, SSA_NAME_VERSION (name));
4824 SET_DEF (def, entry->to_name);
4825 SSA_NAME_DEF_STMT (entry->to_name) = stmt;
4828 /* Rewrite the USE to new ssa name as specified by the mapping MAP. */
4831 rewrite_to_new_ssa_names_use (use_operand_p use, htab_t map)
4833 tree name = USE_FROM_PTR (use);
4834 struct ssa_name_map_entry *entry;
4836 if (TREE_CODE (name) != SSA_NAME)
4839 entry = htab_find_with_hash (map, name, SSA_NAME_VERSION (name));
4843 SET_USE (use, entry->to_name);
4846 /* Rewrite the ssa names in basic block BB to new ones as specified by the
4850 rewrite_to_new_ssa_names_bb (basic_block bb, htab_t map)
4856 block_stmt_iterator bsi;
4860 v_may_def_optype v_may_defs;
4861 v_must_def_optype v_must_defs;
4864 FOR_EACH_EDGE (e, ei, bb->preds)
4865 if (e->flags & EDGE_ABNORMAL)
4868 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
4870 rewrite_to_new_ssa_names_def (PHI_RESULT_PTR (phi), phi, map);
4872 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (PHI_RESULT (phi)) = 1;
4875 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4877 stmt = bsi_stmt (bsi);
4878 get_stmt_operands (stmt);
4879 ann = stmt_ann (stmt);
4881 uses = USE_OPS (ann);
4882 for (i = 0; i < NUM_USES (uses); i++)
4883 rewrite_to_new_ssa_names_use (USE_OP_PTR (uses, i), map);
4885 defs = DEF_OPS (ann);
4886 for (i = 0; i < NUM_DEFS (defs); i++)
4887 rewrite_to_new_ssa_names_def (DEF_OP_PTR (defs, i), stmt, map);
4889 vuses = VUSE_OPS (ann);
4890 for (i = 0; i < NUM_VUSES (vuses); i++)
4891 rewrite_to_new_ssa_names_use (VUSE_OP_PTR (vuses, i), map);
4893 v_may_defs = V_MAY_DEF_OPS (ann);
4894 for (i = 0; i < NUM_V_MAY_DEFS (v_may_defs); i++)
4896 rewrite_to_new_ssa_names_use
4897 (V_MAY_DEF_OP_PTR (v_may_defs, i), map);
4898 rewrite_to_new_ssa_names_def
4899 (V_MAY_DEF_RESULT_PTR (v_may_defs, i), stmt, map);
4902 v_must_defs = V_MUST_DEF_OPS (ann);
4903 for (i = 0; i < NUM_V_MUST_DEFS (v_must_defs); i++)
4905 rewrite_to_new_ssa_names_def
4906 (V_MUST_DEF_RESULT_PTR (v_must_defs, i), stmt, map);
4907 rewrite_to_new_ssa_names_use
4908 (V_MUST_DEF_KILL_PTR (v_must_defs, i), map);
4912 FOR_EACH_EDGE (e, ei, bb->succs)
4913 for (phi = phi_nodes (e->dest); phi; phi = PHI_CHAIN (phi))
4915 rewrite_to_new_ssa_names_use
4916 (PHI_ARG_DEF_PTR_FROM_EDGE (phi, e), map);
4918 if (e->flags & EDGE_ABNORMAL)
4920 tree op = PHI_ARG_DEF_FROM_EDGE (phi, e);
4921 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op) = 1;
4926 /* Rewrite the ssa names in N_REGION blocks REGION to the new ones as specified
4927 by the mapping MAP. */
4930 rewrite_to_new_ssa_names (basic_block *region, unsigned n_region, htab_t map)
4934 for (r = 0; r < n_region; r++)
4935 rewrite_to_new_ssa_names_bb (region[r], map);
4938 /* Duplicates a REGION (set of N_REGION basic blocks) with just a single
4939 important exit edge EXIT. By important we mean that no SSA name defined
4940 inside region is live over the other exit edges of the region. All entry
4941 edges to the region must go to ENTRY->dest. The edge ENTRY is redirected
4942 to the duplicate of the region. SSA form, dominance and loop information
4943 is updated. The new basic blocks are stored to REGION_COPY in the same
4944 order as they had in REGION, provided that REGION_COPY is not NULL.
4945 The function returns false if it is unable to copy the region,
4949 tree_duplicate_sese_region (edge entry, edge exit,
4950 basic_block *region, unsigned n_region,
4951 basic_block *region_copy)
4953 unsigned i, n_doms, ver;
4954 bool free_region_copy = false, copying_header = false;
4955 struct loop *loop = entry->dest->loop_father;
4960 htab_t ssa_name_map = NULL;
4964 if (!can_copy_bbs_p (region, n_region))
4967 /* Some sanity checking. Note that we do not check for all possible
4968 missuses of the functions. I.e. if you ask to copy something weird,
4969 it will work, but the state of structures probably will not be
4972 for (i = 0; i < n_region; i++)
4974 /* We do not handle subloops, i.e. all the blocks must belong to the
4976 if (region[i]->loop_father != loop)
4979 if (region[i] != entry->dest
4980 && region[i] == loop->header)
4986 /* In case the function is used for loop header copying (which is the primary
4987 use), ensure that EXIT and its copy will be new latch and entry edges. */
4988 if (loop->header == entry->dest)
4990 copying_header = true;
4991 loop->copy = loop->outer;
4993 if (!dominated_by_p (CDI_DOMINATORS, loop->latch, exit->src))
4996 for (i = 0; i < n_region; i++)
4997 if (region[i] != exit->src
4998 && dominated_by_p (CDI_DOMINATORS, region[i], exit->src))
5004 region_copy = xmalloc (sizeof (basic_block) * n_region);
5005 free_region_copy = true;
5008 gcc_assert (!any_marked_for_rewrite_p ());
5010 /* Record blocks outside the region that are duplicated by something
5012 doms = xmalloc (sizeof (basic_block) * n_basic_blocks);
5013 n_doms = get_dominated_by_region (CDI_DOMINATORS, region, n_region, doms);
5015 copy_bbs (region, n_region, region_copy, &exit, 1, &exit_copy, loop);
5016 definitions = marked_ssa_names ();
5020 loop->header = exit->dest;
5021 loop->latch = exit->src;
5024 /* Redirect the entry and add the phi node arguments. */
5025 redirected = redirect_edge_and_branch (entry, entry->dest->rbi->copy);
5026 gcc_assert (redirected != NULL);
5027 flush_pending_stmts (entry);
5029 /* Concerning updating of dominators: We must recount dominators
5030 for entry block and its copy. Anything that is outside of the region, but
5031 was dominated by something inside needs recounting as well. */
5032 set_immediate_dominator (CDI_DOMINATORS, entry->dest, entry->src);
5033 doms[n_doms++] = entry->dest->rbi->original;
5034 iterate_fix_dominators (CDI_DOMINATORS, doms, n_doms);
5037 /* Add the other phi node arguments. */
5038 add_phi_args_after_copy (region_copy, n_region);
5040 /* Add phi nodes for definitions at exit. TODO -- once we have immediate
5041 uses, it should be possible to emit phi nodes just for definitions that
5042 are used outside region. */
5043 EXECUTE_IF_SET_IN_BITMAP (definitions, 0, ver, bi)
5045 tree name = ssa_name (ver);
5047 phi = create_phi_node (name, exit->dest);
5048 add_phi_arg (phi, name, exit);
5049 add_phi_arg (phi, name, exit_copy);
5051 SSA_NAME_DEF_STMT (name) = phi;
5054 /* And create new definitions inside region and its copy. TODO -- once we
5055 have immediate uses, it might be better to leave definitions in region
5056 unchanged, create new ssa names for phi nodes on exit, and rewrite
5057 the uses, to avoid changing the copied region. */
5058 allocate_ssa_names (definitions, &ssa_name_map);
5059 rewrite_to_new_ssa_names (region, n_region, ssa_name_map);
5060 allocate_ssa_names (definitions, &ssa_name_map);
5061 rewrite_to_new_ssa_names (region_copy, n_region, ssa_name_map);
5062 htab_delete (ssa_name_map);
5064 if (free_region_copy)
5067 unmark_all_for_rewrite ();
5068 BITMAP_XFREE (definitions);
5073 /* Dump FUNCTION_DECL FN to file FILE using FLAGS (see TDF_* in tree.h) */
5076 dump_function_to_file (tree fn, FILE *file, int flags)
5078 tree arg, vars, var;
5079 bool ignore_topmost_bind = false, any_var = false;
5083 fprintf (file, "%s (", lang_hooks.decl_printable_name (fn, 2));
5085 arg = DECL_ARGUMENTS (fn);
5088 print_generic_expr (file, arg, dump_flags);
5089 if (TREE_CHAIN (arg))
5090 fprintf (file, ", ");
5091 arg = TREE_CHAIN (arg);
5093 fprintf (file, ")\n");
5095 if (flags & TDF_RAW)
5097 dump_node (fn, TDF_SLIM | flags, file);
5101 /* When GIMPLE is lowered, the variables are no longer available in
5102 BIND_EXPRs, so display them separately. */
5103 if (cfun && cfun->unexpanded_var_list)
5105 ignore_topmost_bind = true;
5107 fprintf (file, "{\n");
5108 for (vars = cfun->unexpanded_var_list; vars; vars = TREE_CHAIN (vars))
5110 var = TREE_VALUE (vars);
5112 print_generic_decl (file, var, flags);
5113 fprintf (file, "\n");
5119 if (basic_block_info)
5121 /* Make a CFG based dump. */
5122 check_bb_profile (ENTRY_BLOCK_PTR, file);
5123 if (!ignore_topmost_bind)
5124 fprintf (file, "{\n");
5126 if (any_var && n_basic_blocks)
5127 fprintf (file, "\n");
5130 dump_generic_bb (file, bb, 2, flags);
5132 fprintf (file, "}\n");
5133 check_bb_profile (EXIT_BLOCK_PTR, file);
5139 /* Make a tree based dump. */
5140 chain = DECL_SAVED_TREE (fn);
5142 if (TREE_CODE (chain) == BIND_EXPR)
5144 if (ignore_topmost_bind)
5146 chain = BIND_EXPR_BODY (chain);
5154 if (!ignore_topmost_bind)
5155 fprintf (file, "{\n");
5160 fprintf (file, "\n");
5162 print_generic_stmt_indented (file, chain, flags, indent);
5163 if (ignore_topmost_bind)
5164 fprintf (file, "}\n");
5167 fprintf (file, "\n\n");
5171 /* Pretty print of the loops intermediate representation. */
5172 static void print_loop (FILE *, struct loop *, int);
5173 static void print_pred_bbs (FILE *, basic_block bb);
5174 static void print_succ_bbs (FILE *, basic_block bb);
5177 /* Print the predecessors indexes of edge E on FILE. */
5180 print_pred_bbs (FILE *file, basic_block bb)
5185 FOR_EACH_EDGE (e, ei, bb->preds)
5186 fprintf (file, "bb_%d", e->src->index);
5190 /* Print the successors indexes of edge E on FILE. */
5193 print_succ_bbs (FILE *file, basic_block bb)
5198 FOR_EACH_EDGE (e, ei, bb->succs)
5199 fprintf (file, "bb_%d", e->src->index);
5203 /* Pretty print LOOP on FILE, indented INDENT spaces. */
5206 print_loop (FILE *file, struct loop *loop, int indent)
5214 s_indent = (char *) alloca ((size_t) indent + 1);
5215 memset ((void *) s_indent, ' ', (size_t) indent);
5216 s_indent[indent] = '\0';
5218 /* Print the loop's header. */
5219 fprintf (file, "%sloop_%d\n", s_indent, loop->num);
5221 /* Print the loop's body. */
5222 fprintf (file, "%s{\n", s_indent);
5224 if (bb->loop_father == loop)
5226 /* Print the basic_block's header. */
5227 fprintf (file, "%s bb_%d (preds = {", s_indent, bb->index);
5228 print_pred_bbs (file, bb);
5229 fprintf (file, "}, succs = {");
5230 print_succ_bbs (file, bb);
5231 fprintf (file, "})\n");
5233 /* Print the basic_block's body. */
5234 fprintf (file, "%s {\n", s_indent);
5235 tree_dump_bb (bb, file, indent + 4);
5236 fprintf (file, "%s }\n", s_indent);
5239 print_loop (file, loop->inner, indent + 2);
5240 fprintf (file, "%s}\n", s_indent);
5241 print_loop (file, loop->next, indent);
5245 /* Follow a CFG edge from the entry point of the program, and on entry
5246 of a loop, pretty print the loop structure on FILE. */
5249 print_loop_ir (FILE *file)
5253 bb = BASIC_BLOCK (0);
5254 if (bb && bb->loop_father)
5255 print_loop (file, bb->loop_father, 0);
5259 /* Debugging loops structure at tree level. */
5262 debug_loop_ir (void)
5264 print_loop_ir (stderr);
5268 /* Return true if BB ends with a call, possibly followed by some
5269 instructions that must stay with the call. Return false,
5273 tree_block_ends_with_call_p (basic_block bb)
5275 block_stmt_iterator bsi = bsi_last (bb);
5276 return get_call_expr_in (bsi_stmt (bsi)) != NULL;
5280 /* Return true if BB ends with a conditional branch. Return false,
5284 tree_block_ends_with_condjump_p (basic_block bb)
5286 tree stmt = tsi_stmt (bsi_last (bb).tsi);
5287 return (TREE_CODE (stmt) == COND_EXPR);
5291 /* Return true if we need to add fake edge to exit at statement T.
5292 Helper function for tree_flow_call_edges_add. */
5295 need_fake_edge_p (tree t)
5299 /* NORETURN and LONGJMP calls already have an edge to exit.
5300 CONST, PURE and ALWAYS_RETURN calls do not need one.
5301 We don't currently check for CONST and PURE here, although
5302 it would be a good idea, because those attributes are
5303 figured out from the RTL in mark_constant_function, and
5304 the counter incrementation code from -fprofile-arcs
5305 leads to different results from -fbranch-probabilities. */
5306 call = get_call_expr_in (t);
5308 && !(call_expr_flags (call) & (ECF_NORETURN | ECF_ALWAYS_RETURN)))
5311 if (TREE_CODE (t) == ASM_EXPR
5312 && (ASM_VOLATILE_P (t) || ASM_INPUT_P (t)))
5319 /* Add fake edges to the function exit for any non constant and non
5320 noreturn calls, volatile inline assembly in the bitmap of blocks
5321 specified by BLOCKS or to the whole CFG if BLOCKS is zero. Return
5322 the number of blocks that were split.
5324 The goal is to expose cases in which entering a basic block does
5325 not imply that all subsequent instructions must be executed. */
5328 tree_flow_call_edges_add (sbitmap blocks)
5331 int blocks_split = 0;
5332 int last_bb = last_basic_block;
5333 bool check_last_block = false;
5335 if (n_basic_blocks == 0)
5339 check_last_block = true;
5341 check_last_block = TEST_BIT (blocks, EXIT_BLOCK_PTR->prev_bb->index);
5343 /* In the last basic block, before epilogue generation, there will be
5344 a fallthru edge to EXIT. Special care is required if the last insn
5345 of the last basic block is a call because make_edge folds duplicate
5346 edges, which would result in the fallthru edge also being marked
5347 fake, which would result in the fallthru edge being removed by
5348 remove_fake_edges, which would result in an invalid CFG.
5350 Moreover, we can't elide the outgoing fake edge, since the block
5351 profiler needs to take this into account in order to solve the minimal
5352 spanning tree in the case that the call doesn't return.
5354 Handle this by adding a dummy instruction in a new last basic block. */
5355 if (check_last_block)
5357 basic_block bb = EXIT_BLOCK_PTR->prev_bb;
5358 block_stmt_iterator bsi = bsi_last (bb);
5360 if (!bsi_end_p (bsi))
5363 if (need_fake_edge_p (t))
5367 e = find_edge (bb, EXIT_BLOCK_PTR);
5370 bsi_insert_on_edge (e, build_empty_stmt ());
5371 bsi_commit_edge_inserts ();
5376 /* Now add fake edges to the function exit for any non constant
5377 calls since there is no way that we can determine if they will
5379 for (i = 0; i < last_bb; i++)
5381 basic_block bb = BASIC_BLOCK (i);
5382 block_stmt_iterator bsi;
5383 tree stmt, last_stmt;
5388 if (blocks && !TEST_BIT (blocks, i))
5391 bsi = bsi_last (bb);
5392 if (!bsi_end_p (bsi))
5394 last_stmt = bsi_stmt (bsi);
5397 stmt = bsi_stmt (bsi);
5398 if (need_fake_edge_p (stmt))
5401 /* The handling above of the final block before the
5402 epilogue should be enough to verify that there is
5403 no edge to the exit block in CFG already.
5404 Calling make_edge in such case would cause us to
5405 mark that edge as fake and remove it later. */
5406 #ifdef ENABLE_CHECKING
5407 if (stmt == last_stmt)
5409 e = find_edge (bb, EXIT_BLOCK_PTR);
5410 gcc_assert (e == NULL);
5414 /* Note that the following may create a new basic block
5415 and renumber the existing basic blocks. */
5416 if (stmt != last_stmt)
5418 e = split_block (bb, stmt);
5422 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
5426 while (!bsi_end_p (bsi));
5431 verify_flow_info ();
5433 return blocks_split;
5437 tree_purge_dead_eh_edges (basic_block bb)
5439 bool changed = false;
5442 tree stmt = last_stmt (bb);
5444 if (stmt && tree_can_throw_internal (stmt))
5447 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
5449 if (e->flags & EDGE_EH)
5458 /* Removal of dead EH edges might change dominators of not
5459 just immediate successors. E.g. when bb1 is changed so that
5460 it no longer can throw and bb1->bb3 and bb1->bb4 are dead
5461 eh edges purged by this function in:
5473 idom(bb5) must be recomputed. For now just free the dominance
5476 free_dominance_info (CDI_DOMINATORS);
5482 tree_purge_all_dead_eh_edges (bitmap blocks)
5484 bool changed = false;
5488 EXECUTE_IF_SET_IN_BITMAP (blocks, 0, i, bi)
5490 changed |= tree_purge_dead_eh_edges (BASIC_BLOCK (i));
5496 /* This function is called whenever a new edge is created or
5500 tree_execute_on_growing_pred (edge e)
5502 basic_block bb = e->dest;
5505 reserve_phi_args_for_new_edge (bb);
5508 /* This function is called immediately before edge E is removed from
5509 the edge vector E->dest->preds. */
5512 tree_execute_on_shrinking_pred (edge e)
5514 if (phi_nodes (e->dest))
5515 remove_phi_args (e);
5518 struct cfg_hooks tree_cfg_hooks = {
5520 tree_verify_flow_info,
5521 tree_dump_bb, /* dump_bb */
5522 create_bb, /* create_basic_block */
5523 tree_redirect_edge_and_branch,/* redirect_edge_and_branch */
5524 tree_redirect_edge_and_branch_force,/* redirect_edge_and_branch_force */
5525 remove_bb, /* delete_basic_block */
5526 tree_split_block, /* split_block */
5527 tree_move_block_after, /* move_block_after */
5528 tree_can_merge_blocks_p, /* can_merge_blocks_p */
5529 tree_merge_blocks, /* merge_blocks */
5530 tree_predict_edge, /* predict_edge */
5531 tree_predicted_by_p, /* predicted_by_p */
5532 tree_can_duplicate_bb_p, /* can_duplicate_block_p */
5533 tree_duplicate_bb, /* duplicate_block */
5534 tree_split_edge, /* split_edge */
5535 tree_make_forwarder_block, /* make_forward_block */
5536 NULL, /* tidy_fallthru_edge */
5537 tree_block_ends_with_call_p, /* block_ends_with_call_p */
5538 tree_block_ends_with_condjump_p, /* block_ends_with_condjump_p */
5539 tree_flow_call_edges_add, /* flow_call_edges_add */
5540 tree_execute_on_growing_pred, /* execute_on_growing_pred */
5541 tree_execute_on_shrinking_pred, /* execute_on_shrinking_pred */
5545 /* Split all critical edges. */
5548 split_critical_edges (void)
5554 /* split_edge can redirect edges out of SWITCH_EXPRs, which can get
5555 expensive. So we want to enable recording of edge to CASE_LABEL_EXPR
5556 mappings around the calls to split_edge. */
5557 start_recording_case_labels ();
5560 FOR_EACH_EDGE (e, ei, bb->succs)
5561 if (EDGE_CRITICAL_P (e) && !(e->flags & EDGE_ABNORMAL))
5566 end_recording_case_labels ();
5569 struct tree_opt_pass pass_split_crit_edges =
5571 "crited", /* name */
5573 split_critical_edges, /* execute */
5576 0, /* static_pass_number */
5577 TV_TREE_SPLIT_EDGES, /* tv_id */
5578 PROP_cfg, /* properties required */
5579 PROP_no_crit_edges, /* properties_provided */
5580 0, /* properties_destroyed */
5581 0, /* todo_flags_start */
5582 TODO_dump_func, /* todo_flags_finish */
5587 /* Return EXP if it is a valid GIMPLE rvalue, else gimplify it into
5588 a temporary, make sure and register it to be renamed if necessary,
5589 and finally return the temporary. Put the statements to compute
5590 EXP before the current statement in BSI. */
5593 gimplify_val (block_stmt_iterator *bsi, tree type, tree exp)
5595 tree t, new_stmt, orig_stmt;
5597 if (is_gimple_val (exp))
5600 t = make_rename_temp (type, NULL);
5601 new_stmt = build (MODIFY_EXPR, type, t, exp);
5603 orig_stmt = bsi_stmt (*bsi);
5604 SET_EXPR_LOCUS (new_stmt, EXPR_LOCUS (orig_stmt));
5605 TREE_BLOCK (new_stmt) = TREE_BLOCK (orig_stmt);
5607 bsi_insert_before (bsi, new_stmt, BSI_SAME_STMT);
5612 /* Build a ternary operation and gimplify it. Emit code before BSI.
5613 Return the gimple_val holding the result. */
5616 gimplify_build3 (block_stmt_iterator *bsi, enum tree_code code,
5617 tree type, tree a, tree b, tree c)
5621 ret = fold (build3 (code, type, a, b, c));
5624 return gimplify_val (bsi, type, ret);
5627 /* Build a binary operation and gimplify it. Emit code before BSI.
5628 Return the gimple_val holding the result. */
5631 gimplify_build2 (block_stmt_iterator *bsi, enum tree_code code,
5632 tree type, tree a, tree b)
5636 ret = fold (build2 (code, type, a, b));
5639 return gimplify_val (bsi, type, ret);
5642 /* Build a unary operation and gimplify it. Emit code before BSI.
5643 Return the gimple_val holding the result. */
5646 gimplify_build1 (block_stmt_iterator *bsi, enum tree_code code, tree type,
5651 ret = fold (build1 (code, type, a));
5654 return gimplify_val (bsi, type, ret);
5659 /* Emit return warnings. */
5662 execute_warn_function_return (void)
5664 #ifdef USE_MAPPED_LOCATION
5665 source_location location;
5673 if (warn_missing_noreturn
5674 && !TREE_THIS_VOLATILE (cfun->decl)
5675 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) == 0
5676 && !lang_hooks.function.missing_noreturn_ok_p (cfun->decl))
5677 warning ("%Jfunction might be possible candidate for "
5678 "attribute %<noreturn%>",
5681 /* If we have a path to EXIT, then we do return. */
5682 if (TREE_THIS_VOLATILE (cfun->decl)
5683 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) > 0)
5685 #ifdef USE_MAPPED_LOCATION
5686 location = UNKNOWN_LOCATION;
5690 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
5692 last = last_stmt (e->src);
5693 if (TREE_CODE (last) == RETURN_EXPR
5694 #ifdef USE_MAPPED_LOCATION
5695 && (location = EXPR_LOCATION (last)) != UNKNOWN_LOCATION)
5697 && (locus = EXPR_LOCUS (last)) != NULL)
5701 #ifdef USE_MAPPED_LOCATION
5702 if (location == UNKNOWN_LOCATION)
5703 location = cfun->function_end_locus;
5704 warning ("%H%<noreturn%> function does return", &location);
5707 locus = &cfun->function_end_locus;
5708 warning ("%H%<noreturn%> function does return", locus);
5712 /* If we see "return;" in some basic block, then we do reach the end
5713 without returning a value. */
5714 else if (warn_return_type
5715 && !TREE_NO_WARNING (cfun->decl)
5716 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) > 0
5717 && !VOID_TYPE_P (TREE_TYPE (TREE_TYPE (cfun->decl))))
5719 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
5721 tree last = last_stmt (e->src);
5722 if (TREE_CODE (last) == RETURN_EXPR
5723 && TREE_OPERAND (last, 0) == NULL)
5725 #ifdef USE_MAPPED_LOCATION
5726 location = EXPR_LOCATION (last);
5727 if (location == UNKNOWN_LOCATION)
5728 location = cfun->function_end_locus;
5729 warning ("%Hcontrol reaches end of non-void function", &location);
5731 locus = EXPR_LOCUS (last);
5733 locus = &cfun->function_end_locus;
5734 warning ("%Hcontrol reaches end of non-void function", locus);
5736 TREE_NO_WARNING (cfun->decl) = 1;
5744 /* Given a basic block B which ends with a conditional and has
5745 precisely two successors, determine which of the edges is taken if
5746 the conditional is true and which is taken if the conditional is
5747 false. Set TRUE_EDGE and FALSE_EDGE appropriately. */
5750 extract_true_false_edges_from_block (basic_block b,
5754 edge e = EDGE_SUCC (b, 0);
5756 if (e->flags & EDGE_TRUE_VALUE)
5759 *false_edge = EDGE_SUCC (b, 1);
5764 *true_edge = EDGE_SUCC (b, 1);
5768 struct tree_opt_pass pass_warn_function_return =
5772 execute_warn_function_return, /* execute */
5775 0, /* static_pass_number */
5777 PROP_cfg, /* properties_required */
5778 0, /* properties_provided */
5779 0, /* properties_destroyed */
5780 0, /* todo_flags_start */
5781 0, /* todo_flags_finish */
5785 #include "gt-tree-cfg.h"