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 /* A list of all the noreturn calls passed to modify_stmt.
2056 cleanup_control_flow uses it to detect cases where a mid-block
2057 indirect call has been turned into a noreturn call. When this
2058 happens, all the instructions after the call are no longer
2059 reachable and must be deleted as dead. */
2061 VEC(tree
) *modified_noreturn_calls
;
2063 /* Try to remove superfluous control structures. */
2066 cleanup_control_flow (void)
2069 block_stmt_iterator bsi
;
2070 bool retval
= false;
2073 /* Detect cases where a mid-block call is now known not to return. */
2074 while (VEC_length (tree
, modified_noreturn_calls
))
2076 stmt
= VEC_pop (tree
, modified_noreturn_calls
);
2077 bb
= bb_for_stmt (stmt
);
2078 if (bb
!= NULL
&& last_stmt (bb
) != stmt
&& noreturn_call_p (stmt
))
2079 split_block (bb
, stmt
);
2084 bsi
= bsi_last (bb
);
2086 if (bsi_end_p (bsi
))
2089 stmt
= bsi_stmt (bsi
);
2090 if (TREE_CODE (stmt
) == COND_EXPR
2091 || TREE_CODE (stmt
) == SWITCH_EXPR
)
2092 retval
|= cleanup_control_expr_graph (bb
, bsi
);
2094 /* Check for indirect calls that have been turned into
2096 if (noreturn_call_p (stmt
) && remove_fallthru_edge (bb
->succs
))
2098 free_dominance_info (CDI_DOMINATORS
);
2106 /* Disconnect an unreachable block in the control expression starting
2110 cleanup_control_expr_graph (basic_block bb
, block_stmt_iterator bsi
)
2113 bool retval
= false;
2114 tree expr
= bsi_stmt (bsi
), val
;
2116 if (EDGE_COUNT (bb
->succs
) > 1)
2121 switch (TREE_CODE (expr
))
2124 val
= COND_EXPR_COND (expr
);
2128 val
= SWITCH_COND (expr
);
2129 if (TREE_CODE (val
) != INTEGER_CST
)
2137 taken_edge
= find_taken_edge (bb
, val
);
2141 /* Remove all the edges except the one that is always executed. */
2142 for (ei
= ei_start (bb
->succs
); (e
= ei_safe_edge (ei
)); )
2144 if (e
!= taken_edge
)
2146 taken_edge
->probability
+= e
->probability
;
2147 taken_edge
->count
+= e
->count
;
2154 if (taken_edge
->probability
> REG_BR_PROB_BASE
)
2155 taken_edge
->probability
= REG_BR_PROB_BASE
;
2158 taken_edge
= EDGE_SUCC (bb
, 0);
2161 taken_edge
->flags
= EDGE_FALLTHRU
;
2163 /* We removed some paths from the cfg. */
2164 free_dominance_info (CDI_DOMINATORS
);
2169 /* Remove any fallthru edge from EV. Return true if an edge was removed. */
2172 remove_fallthru_edge (VEC(edge
) *ev
)
2177 FOR_EACH_EDGE (e
, ei
, ev
)
2178 if ((e
->flags
& EDGE_FALLTHRU
) != 0)
2186 /* Given a basic block BB ending with COND_EXPR or SWITCH_EXPR, and a
2187 predicate VAL, return the edge that will be taken out of the block.
2188 If VAL does not match a unique edge, NULL is returned. */
2191 find_taken_edge (basic_block bb
, tree val
)
2195 stmt
= last_stmt (bb
);
2198 gcc_assert (is_ctrl_stmt (stmt
));
2201 /* If VAL is a predicate of the form N RELOP N, where N is an
2202 SSA_NAME, we can usually determine its truth value. */
2203 if (COMPARISON_CLASS_P (val
))
2206 /* If VAL is not a constant, we can't determine which edge might
2208 if (!really_constant_p (val
))
2211 if (TREE_CODE (stmt
) == COND_EXPR
)
2212 return find_taken_edge_cond_expr (bb
, val
);
2214 if (TREE_CODE (stmt
) == SWITCH_EXPR
)
2215 return find_taken_edge_switch_expr (bb
, val
);
2221 /* Given a constant value VAL and the entry block BB to a COND_EXPR
2222 statement, determine which of the two edges will be taken out of the
2223 block. Return NULL if either edge may be taken. */
2226 find_taken_edge_cond_expr (basic_block bb
, tree val
)
2228 edge true_edge
, false_edge
;
2230 extract_true_false_edges_from_block (bb
, &true_edge
, &false_edge
);
2232 /* Otherwise, try to determine which branch of the if() will be taken.
2233 If VAL is a constant but it can't be reduced to a 0 or a 1, then
2234 we don't really know which edge will be taken at runtime. This
2235 may happen when comparing addresses (e.g., if (&var1 == 4)). */
2236 if (integer_nonzerop (val
))
2238 else if (integer_zerop (val
))
2245 /* Given a constant value VAL and the entry block BB to a SWITCH_EXPR
2246 statement, determine which edge will be taken out of the block. Return
2247 NULL if any edge may be taken. */
2250 find_taken_edge_switch_expr (basic_block bb
, tree val
)
2252 tree switch_expr
, taken_case
;
2253 basic_block dest_bb
;
2256 if (TREE_CODE (val
) != INTEGER_CST
)
2259 switch_expr
= last_stmt (bb
);
2260 taken_case
= find_case_label_for_value (switch_expr
, val
);
2261 dest_bb
= label_to_block (CASE_LABEL (taken_case
));
2263 e
= find_edge (bb
, dest_bb
);
2269 /* Return the CASE_LABEL_EXPR that SWITCH_EXPR will take for VAL.
2270 We can make optimal use here of the fact that the case labels are
2271 sorted: We can do a binary search for a case matching VAL. */
2274 find_case_label_for_value (tree switch_expr
, tree val
)
2276 tree vec
= SWITCH_LABELS (switch_expr
);
2277 size_t low
, high
, n
= TREE_VEC_LENGTH (vec
);
2278 tree default_case
= TREE_VEC_ELT (vec
, n
- 1);
2280 for (low
= -1, high
= n
- 1; high
- low
> 1; )
2282 size_t i
= (high
+ low
) / 2;
2283 tree t
= TREE_VEC_ELT (vec
, i
);
2286 /* Cache the result of comparing CASE_LOW and val. */
2287 cmp
= tree_int_cst_compare (CASE_LOW (t
), val
);
2294 if (CASE_HIGH (t
) == NULL
)
2296 /* A singe-valued case label. */
2302 /* A case range. We can only handle integer ranges. */
2303 if (cmp
<= 0 && tree_int_cst_compare (CASE_HIGH (t
), val
) >= 0)
2308 return default_case
;
2312 /* If all the PHI nodes in DEST have alternatives for E1 and E2 and
2313 those alternatives are equal in each of the PHI nodes, then return
2314 true, else return false. */
2317 phi_alternatives_equal (basic_block dest
, edge e1
, edge e2
)
2319 int n1
= e1
->dest_idx
;
2320 int n2
= e2
->dest_idx
;
2323 for (phi
= phi_nodes (dest
); phi
; phi
= PHI_CHAIN (phi
))
2325 tree val1
= PHI_ARG_DEF (phi
, n1
);
2326 tree val2
= PHI_ARG_DEF (phi
, n2
);
2328 gcc_assert (val1
!= NULL_TREE
);
2329 gcc_assert (val2
!= NULL_TREE
);
2331 if (!operand_equal_for_phi_arg_p (val1
, val2
))
2339 /*---------------------------------------------------------------------------
2341 ---------------------------------------------------------------------------*/
2343 /* Dump tree-specific information of block BB to file OUTF. */
2346 tree_dump_bb (basic_block bb
, FILE *outf
, int indent
)
2348 dump_generic_bb (outf
, bb
, indent
, TDF_VOPS
);
2352 /* Dump a basic block on stderr. */
2355 debug_tree_bb (basic_block bb
)
2357 dump_bb (bb
, stderr
, 0);
2361 /* Dump basic block with index N on stderr. */
2364 debug_tree_bb_n (int n
)
2366 debug_tree_bb (BASIC_BLOCK (n
));
2367 return BASIC_BLOCK (n
);
2371 /* Dump the CFG on stderr.
2373 FLAGS are the same used by the tree dumping functions
2374 (see TDF_* in tree.h). */
2377 debug_tree_cfg (int flags
)
2379 dump_tree_cfg (stderr
, flags
);
2383 /* Dump the program showing basic block boundaries on the given FILE.
2385 FLAGS are the same used by the tree dumping functions (see TDF_* in
2389 dump_tree_cfg (FILE *file
, int flags
)
2391 if (flags
& TDF_DETAILS
)
2393 const char *funcname
2394 = lang_hooks
.decl_printable_name (current_function_decl
, 2);
2397 fprintf (file
, ";; Function %s\n\n", funcname
);
2398 fprintf (file
, ";; \n%d basic blocks, %d edges, last basic block %d.\n\n",
2399 n_basic_blocks
, n_edges
, last_basic_block
);
2401 brief_dump_cfg (file
);
2402 fprintf (file
, "\n");
2405 if (flags
& TDF_STATS
)
2406 dump_cfg_stats (file
);
2408 dump_function_to_file (current_function_decl
, file
, flags
| TDF_BLOCKS
);
2412 /* Dump CFG statistics on FILE. */
2415 dump_cfg_stats (FILE *file
)
2417 static long max_num_merged_labels
= 0;
2418 unsigned long size
, total
= 0;
2421 const char * const fmt_str
= "%-30s%-13s%12s\n";
2422 const char * const fmt_str_1
= "%-30s%13d%11lu%c\n";
2423 const char * const fmt_str_3
= "%-43s%11lu%c\n";
2424 const char *funcname
2425 = lang_hooks
.decl_printable_name (current_function_decl
, 2);
2428 fprintf (file
, "\nCFG Statistics for %s\n\n", funcname
);
2430 fprintf (file
, "---------------------------------------------------------\n");
2431 fprintf (file
, fmt_str
, "", " Number of ", "Memory");
2432 fprintf (file
, fmt_str
, "", " instances ", "used ");
2433 fprintf (file
, "---------------------------------------------------------\n");
2435 size
= n_basic_blocks
* sizeof (struct basic_block_def
);
2437 fprintf (file
, fmt_str_1
, "Basic blocks", n_basic_blocks
,
2438 SCALE (size
), LABEL (size
));
2442 n_edges
+= EDGE_COUNT (bb
->succs
);
2443 size
= n_edges
* sizeof (struct edge_def
);
2445 fprintf (file
, fmt_str_1
, "Edges", n_edges
, SCALE (size
), LABEL (size
));
2447 size
= n_basic_blocks
* sizeof (struct bb_ann_d
);
2449 fprintf (file
, fmt_str_1
, "Basic block annotations", n_basic_blocks
,
2450 SCALE (size
), LABEL (size
));
2452 fprintf (file
, "---------------------------------------------------------\n");
2453 fprintf (file
, fmt_str_3
, "Total memory used by CFG data", SCALE (total
),
2455 fprintf (file
, "---------------------------------------------------------\n");
2456 fprintf (file
, "\n");
2458 if (cfg_stats
.num_merged_labels
> max_num_merged_labels
)
2459 max_num_merged_labels
= cfg_stats
.num_merged_labels
;
2461 fprintf (file
, "Coalesced label blocks: %ld (Max so far: %ld)\n",
2462 cfg_stats
.num_merged_labels
, max_num_merged_labels
);
2464 fprintf (file
, "\n");
2468 /* Dump CFG statistics on stderr. Keep extern so that it's always
2469 linked in the final executable. */
2472 debug_cfg_stats (void)
2474 dump_cfg_stats (stderr
);
2478 /* Dump the flowgraph to a .vcg FILE. */
2481 tree_cfg2vcg (FILE *file
)
2486 const char *funcname
2487 = lang_hooks
.decl_printable_name (current_function_decl
, 2);
2489 /* Write the file header. */
2490 fprintf (file
, "graph: { title: \"%s\"\n", funcname
);
2491 fprintf (file
, "node: { title: \"ENTRY\" label: \"ENTRY\" }\n");
2492 fprintf (file
, "node: { title: \"EXIT\" label: \"EXIT\" }\n");
2494 /* Write blocks and edges. */
2495 FOR_EACH_EDGE (e
, ei
, ENTRY_BLOCK_PTR
->succs
)
2497 fprintf (file
, "edge: { sourcename: \"ENTRY\" targetname: \"%d\"",
2500 if (e
->flags
& EDGE_FAKE
)
2501 fprintf (file
, " linestyle: dotted priority: 10");
2503 fprintf (file
, " linestyle: solid priority: 100");
2505 fprintf (file
, " }\n");
2511 enum tree_code head_code
, end_code
;
2512 const char *head_name
, *end_name
;
2515 tree first
= first_stmt (bb
);
2516 tree last
= last_stmt (bb
);
2520 head_code
= TREE_CODE (first
);
2521 head_name
= tree_code_name
[head_code
];
2522 head_line
= get_lineno (first
);
2525 head_name
= "no-statement";
2529 end_code
= TREE_CODE (last
);
2530 end_name
= tree_code_name
[end_code
];
2531 end_line
= get_lineno (last
);
2534 end_name
= "no-statement";
2536 fprintf (file
, "node: { title: \"%d\" label: \"#%d\\n%s (%d)\\n%s (%d)\"}\n",
2537 bb
->index
, bb
->index
, head_name
, head_line
, end_name
,
2540 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
2542 if (e
->dest
== EXIT_BLOCK_PTR
)
2543 fprintf (file
, "edge: { sourcename: \"%d\" targetname: \"EXIT\"", bb
->index
);
2545 fprintf (file
, "edge: { sourcename: \"%d\" targetname: \"%d\"", bb
->index
, e
->dest
->index
);
2547 if (e
->flags
& EDGE_FAKE
)
2548 fprintf (file
, " priority: 10 linestyle: dotted");
2550 fprintf (file
, " priority: 100 linestyle: solid");
2552 fprintf (file
, " }\n");
2555 if (bb
->next_bb
!= EXIT_BLOCK_PTR
)
2559 fputs ("}\n\n", file
);
2564 /*---------------------------------------------------------------------------
2565 Miscellaneous helpers
2566 ---------------------------------------------------------------------------*/
2568 /* Return true if T represents a stmt that always transfers control. */
2571 is_ctrl_stmt (tree t
)
2573 return (TREE_CODE (t
) == COND_EXPR
2574 || TREE_CODE (t
) == SWITCH_EXPR
2575 || TREE_CODE (t
) == GOTO_EXPR
2576 || TREE_CODE (t
) == RETURN_EXPR
2577 || TREE_CODE (t
) == RESX_EXPR
);
2581 /* Return true if T is a statement that may alter the flow of control
2582 (e.g., a call to a non-returning function). */
2585 is_ctrl_altering_stmt (tree t
)
2590 call
= get_call_expr_in (t
);
2593 /* A non-pure/const CALL_EXPR alters flow control if the current
2594 function has nonlocal labels. */
2595 if (TREE_SIDE_EFFECTS (call
) && current_function_has_nonlocal_label
)
2598 /* A CALL_EXPR also alters control flow if it does not return. */
2599 if (call_expr_flags (call
) & ECF_NORETURN
)
2603 /* If a statement can throw, it alters control flow. */
2604 return tree_can_throw_internal (t
);
2608 /* Return true if T is a computed goto. */
2611 computed_goto_p (tree t
)
2613 return (TREE_CODE (t
) == GOTO_EXPR
2614 && TREE_CODE (GOTO_DESTINATION (t
)) != LABEL_DECL
);
2618 /* Checks whether EXPR is a simple local goto. */
2621 simple_goto_p (tree expr
)
2623 return (TREE_CODE (expr
) == GOTO_EXPR
2624 && TREE_CODE (GOTO_DESTINATION (expr
)) == LABEL_DECL
);
2628 /* Return true if T should start a new basic block. PREV_T is the
2629 statement preceding T. It is used when T is a label or a case label.
2630 Labels should only start a new basic block if their previous statement
2631 wasn't a label. Otherwise, sequence of labels would generate
2632 unnecessary basic blocks that only contain a single label. */
2635 stmt_starts_bb_p (tree t
, tree prev_t
)
2637 enum tree_code code
;
2642 /* LABEL_EXPRs start a new basic block only if the preceding
2643 statement wasn't a label of the same type. This prevents the
2644 creation of consecutive blocks that have nothing but a single
2646 code
= TREE_CODE (t
);
2647 if (code
== LABEL_EXPR
)
2649 /* Nonlocal and computed GOTO targets always start a new block. */
2650 if (code
== LABEL_EXPR
2651 && (DECL_NONLOCAL (LABEL_EXPR_LABEL (t
))
2652 || FORCED_LABEL (LABEL_EXPR_LABEL (t
))))
2655 if (prev_t
&& TREE_CODE (prev_t
) == code
)
2657 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (prev_t
)))
2660 cfg_stats
.num_merged_labels
++;
2671 /* Return true if T should end a basic block. */
2674 stmt_ends_bb_p (tree t
)
2676 return is_ctrl_stmt (t
) || is_ctrl_altering_stmt (t
);
2680 /* Add gotos that used to be represented implicitly in the CFG. */
2683 disband_implicit_edges (void)
2686 block_stmt_iterator last
;
2693 last
= bsi_last (bb
);
2694 stmt
= last_stmt (bb
);
2696 if (stmt
&& TREE_CODE (stmt
) == COND_EXPR
)
2698 /* Remove superfluous gotos from COND_EXPR branches. Moved
2699 from cfg_remove_useless_stmts here since it violates the
2700 invariants for tree--cfg correspondence and thus fits better
2701 here where we do it anyway. */
2702 e
= find_edge (bb
, bb
->next_bb
);
2705 if (e
->flags
& EDGE_TRUE_VALUE
)
2706 COND_EXPR_THEN (stmt
) = build_empty_stmt ();
2707 else if (e
->flags
& EDGE_FALSE_VALUE
)
2708 COND_EXPR_ELSE (stmt
) = build_empty_stmt ();
2711 e
->flags
|= EDGE_FALLTHRU
;
2717 if (stmt
&& TREE_CODE (stmt
) == RETURN_EXPR
)
2719 /* Remove the RETURN_EXPR if we may fall though to the exit
2721 gcc_assert (EDGE_COUNT (bb
->succs
) == 1);
2722 gcc_assert (EDGE_SUCC (bb
, 0)->dest
== EXIT_BLOCK_PTR
);
2724 if (bb
->next_bb
== EXIT_BLOCK_PTR
2725 && !TREE_OPERAND (stmt
, 0))
2728 EDGE_SUCC (bb
, 0)->flags
|= EDGE_FALLTHRU
;
2733 /* There can be no fallthru edge if the last statement is a control
2735 if (stmt
&& is_ctrl_stmt (stmt
))
2738 /* Find a fallthru edge and emit the goto if necessary. */
2739 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
2740 if (e
->flags
& EDGE_FALLTHRU
)
2743 if (!e
|| e
->dest
== bb
->next_bb
)
2746 gcc_assert (e
->dest
!= EXIT_BLOCK_PTR
);
2747 label
= tree_block_label (e
->dest
);
2749 stmt
= build1 (GOTO_EXPR
, void_type_node
, label
);
2750 #ifdef USE_MAPPED_LOCATION
2751 SET_EXPR_LOCATION (stmt
, e
->goto_locus
);
2753 SET_EXPR_LOCUS (stmt
, e
->goto_locus
);
2755 bsi_insert_after (&last
, stmt
, BSI_NEW_STMT
);
2756 e
->flags
&= ~EDGE_FALLTHRU
;
2760 /* Remove block annotations and other datastructures. */
2763 delete_tree_cfg_annotations (void)
2766 if (n_basic_blocks
> 0)
2767 free_blocks_annotations ();
2769 label_to_block_map
= NULL
;
2776 /* Return the first statement in basic block BB. */
2779 first_stmt (basic_block bb
)
2781 block_stmt_iterator i
= bsi_start (bb
);
2782 return !bsi_end_p (i
) ? bsi_stmt (i
) : NULL_TREE
;
2786 /* Return the last statement in basic block BB. */
2789 last_stmt (basic_block bb
)
2791 block_stmt_iterator b
= bsi_last (bb
);
2792 return !bsi_end_p (b
) ? bsi_stmt (b
) : NULL_TREE
;
2796 /* Return a pointer to the last statement in block BB. */
2799 last_stmt_ptr (basic_block bb
)
2801 block_stmt_iterator last
= bsi_last (bb
);
2802 return !bsi_end_p (last
) ? bsi_stmt_ptr (last
) : NULL
;
2806 /* Return the last statement of an otherwise empty block. Return NULL
2807 if the block is totally empty, or if it contains more than one
2811 last_and_only_stmt (basic_block bb
)
2813 block_stmt_iterator i
= bsi_last (bb
);
2819 last
= bsi_stmt (i
);
2824 /* Empty statements should no longer appear in the instruction stream.
2825 Everything that might have appeared before should be deleted by
2826 remove_useless_stmts, and the optimizers should just bsi_remove
2827 instead of smashing with build_empty_stmt.
2829 Thus the only thing that should appear here in a block containing
2830 one executable statement is a label. */
2831 prev
= bsi_stmt (i
);
2832 if (TREE_CODE (prev
) == LABEL_EXPR
)
2839 /* Mark BB as the basic block holding statement T. */
2842 set_bb_for_stmt (tree t
, basic_block bb
)
2844 if (TREE_CODE (t
) == PHI_NODE
)
2846 else if (TREE_CODE (t
) == STATEMENT_LIST
)
2848 tree_stmt_iterator i
;
2849 for (i
= tsi_start (t
); !tsi_end_p (i
); tsi_next (&i
))
2850 set_bb_for_stmt (tsi_stmt (i
), bb
);
2854 stmt_ann_t ann
= get_stmt_ann (t
);
2857 /* If the statement is a label, add the label to block-to-labels map
2858 so that we can speed up edge creation for GOTO_EXPRs. */
2859 if (TREE_CODE (t
) == LABEL_EXPR
)
2863 t
= LABEL_EXPR_LABEL (t
);
2864 uid
= LABEL_DECL_UID (t
);
2867 LABEL_DECL_UID (t
) = uid
= cfun
->last_label_uid
++;
2868 if (VARRAY_SIZE (label_to_block_map
) <= (unsigned) uid
)
2869 VARRAY_GROW (label_to_block_map
, 3 * uid
/ 2);
2872 /* We're moving an existing label. Make sure that we've
2873 removed it from the old block. */
2874 gcc_assert (!bb
|| !VARRAY_BB (label_to_block_map
, uid
));
2875 VARRAY_BB (label_to_block_map
, uid
) = bb
;
2880 /* Finds iterator for STMT. */
2882 extern block_stmt_iterator
2883 bsi_for_stmt (tree stmt
)
2885 block_stmt_iterator bsi
;
2887 for (bsi
= bsi_start (bb_for_stmt (stmt
)); !bsi_end_p (bsi
); bsi_next (&bsi
))
2888 if (bsi_stmt (bsi
) == stmt
)
2894 /* Insert statement (or statement list) T before the statement
2895 pointed-to by iterator I. M specifies how to update iterator I
2896 after insertion (see enum bsi_iterator_update). */
2899 bsi_insert_before (block_stmt_iterator
*i
, tree t
, enum bsi_iterator_update m
)
2901 set_bb_for_stmt (t
, i
->bb
);
2902 tsi_link_before (&i
->tsi
, t
, m
);
2907 /* Insert statement (or statement list) T after the statement
2908 pointed-to by iterator I. M specifies how to update iterator I
2909 after insertion (see enum bsi_iterator_update). */
2912 bsi_insert_after (block_stmt_iterator
*i
, tree t
, enum bsi_iterator_update m
)
2914 set_bb_for_stmt (t
, i
->bb
);
2915 tsi_link_after (&i
->tsi
, t
, m
);
2920 /* Remove the statement pointed to by iterator I. The iterator is updated
2921 to the next statement. */
2924 bsi_remove (block_stmt_iterator
*i
)
2926 tree t
= bsi_stmt (*i
);
2927 set_bb_for_stmt (t
, NULL
);
2928 tsi_delink (&i
->tsi
);
2932 /* Move the statement at FROM so it comes right after the statement at TO. */
2935 bsi_move_after (block_stmt_iterator
*from
, block_stmt_iterator
*to
)
2937 tree stmt
= bsi_stmt (*from
);
2939 bsi_insert_after (to
, stmt
, BSI_SAME_STMT
);
2943 /* Move the statement at FROM so it comes right before the statement at TO. */
2946 bsi_move_before (block_stmt_iterator
*from
, block_stmt_iterator
*to
)
2948 tree stmt
= bsi_stmt (*from
);
2950 bsi_insert_before (to
, stmt
, BSI_SAME_STMT
);
2954 /* Move the statement at FROM to the end of basic block BB. */
2957 bsi_move_to_bb_end (block_stmt_iterator
*from
, basic_block bb
)
2959 block_stmt_iterator last
= bsi_last (bb
);
2961 /* Have to check bsi_end_p because it could be an empty block. */
2962 if (!bsi_end_p (last
) && is_ctrl_stmt (bsi_stmt (last
)))
2963 bsi_move_before (from
, &last
);
2965 bsi_move_after (from
, &last
);
2969 /* Replace the contents of the statement pointed to by iterator BSI
2970 with STMT. If PRESERVE_EH_INFO is true, the exception handling
2971 information of the original statement is preserved. */
2974 bsi_replace (const block_stmt_iterator
*bsi
, tree stmt
, bool preserve_eh_info
)
2977 tree orig_stmt
= bsi_stmt (*bsi
);
2979 SET_EXPR_LOCUS (stmt
, EXPR_LOCUS (orig_stmt
));
2980 set_bb_for_stmt (stmt
, bsi
->bb
);
2982 /* Preserve EH region information from the original statement, if
2983 requested by the caller. */
2984 if (preserve_eh_info
)
2986 eh_region
= lookup_stmt_eh_region (orig_stmt
);
2988 add_stmt_to_eh_region (stmt
, eh_region
);
2991 *bsi_stmt_ptr (*bsi
) = stmt
;
2996 /* Insert the statement pointed-to by BSI into edge E. Every attempt
2997 is made to place the statement in an existing basic block, but
2998 sometimes that isn't possible. When it isn't possible, the edge is
2999 split and the statement is added to the new block.
3001 In all cases, the returned *BSI points to the correct location. The
3002 return value is true if insertion should be done after the location,
3003 or false if it should be done before the location. If new basic block
3004 has to be created, it is stored in *NEW_BB. */
3007 tree_find_edge_insert_loc (edge e
, block_stmt_iterator
*bsi
,
3008 basic_block
*new_bb
)
3010 basic_block dest
, src
;
3016 /* If the destination has one predecessor which has no PHI nodes,
3017 insert there. Except for the exit block.
3019 The requirement for no PHI nodes could be relaxed. Basically we
3020 would have to examine the PHIs to prove that none of them used
3021 the value set by the statement we want to insert on E. That
3022 hardly seems worth the effort. */
3023 if (EDGE_COUNT (dest
->preds
) == 1
3024 && ! phi_nodes (dest
)
3025 && dest
!= EXIT_BLOCK_PTR
)
3027 *bsi
= bsi_start (dest
);
3028 if (bsi_end_p (*bsi
))
3031 /* Make sure we insert after any leading labels. */
3032 tmp
= bsi_stmt (*bsi
);
3033 while (TREE_CODE (tmp
) == LABEL_EXPR
)
3036 if (bsi_end_p (*bsi
))
3038 tmp
= bsi_stmt (*bsi
);
3041 if (bsi_end_p (*bsi
))
3043 *bsi
= bsi_last (dest
);
3050 /* If the source has one successor, the edge is not abnormal and
3051 the last statement does not end a basic block, insert there.
3052 Except for the entry block. */
3054 if ((e
->flags
& EDGE_ABNORMAL
) == 0
3055 && EDGE_COUNT (src
->succs
) == 1
3056 && src
!= ENTRY_BLOCK_PTR
)
3058 *bsi
= bsi_last (src
);
3059 if (bsi_end_p (*bsi
))
3062 tmp
= bsi_stmt (*bsi
);
3063 if (!stmt_ends_bb_p (tmp
))
3066 /* Insert code just before returning the value. We may need to decompose
3067 the return in the case it contains non-trivial operand. */
3068 if (TREE_CODE (tmp
) == RETURN_EXPR
)
3070 tree op
= TREE_OPERAND (tmp
, 0);
3071 if (!is_gimple_val (op
))
3073 gcc_assert (TREE_CODE (op
) == MODIFY_EXPR
);
3074 bsi_insert_before (bsi
, op
, BSI_NEW_STMT
);
3075 TREE_OPERAND (tmp
, 0) = TREE_OPERAND (op
, 0);
3082 /* Otherwise, create a new basic block, and split this edge. */
3083 dest
= split_edge (e
);
3086 e
= EDGE_PRED (dest
, 0);
3091 /* This routine will commit all pending edge insertions, creating any new
3092 basic blocks which are necessary. */
3095 bsi_commit_edge_inserts (void)
3101 bsi_commit_one_edge_insert (EDGE_SUCC (ENTRY_BLOCK_PTR
, 0), NULL
);
3104 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
3105 bsi_commit_one_edge_insert (e
, NULL
);
3109 /* Commit insertions pending at edge E. If a new block is created, set NEW_BB
3110 to this block, otherwise set it to NULL. */
3113 bsi_commit_one_edge_insert (edge e
, basic_block
*new_bb
)
3117 if (PENDING_STMT (e
))
3119 block_stmt_iterator bsi
;
3120 tree stmt
= PENDING_STMT (e
);
3122 PENDING_STMT (e
) = NULL_TREE
;
3124 if (tree_find_edge_insert_loc (e
, &bsi
, new_bb
))
3125 bsi_insert_after (&bsi
, stmt
, BSI_NEW_STMT
);
3127 bsi_insert_before (&bsi
, stmt
, BSI_NEW_STMT
);
3132 /* Add STMT to the pending list of edge E. No actual insertion is
3133 made until a call to bsi_commit_edge_inserts () is made. */
3136 bsi_insert_on_edge (edge e
, tree stmt
)
3138 append_to_statement_list (stmt
, &PENDING_STMT (e
));
3141 /* Similar to bsi_insert_on_edge+bsi_commit_edge_inserts. If a new
3142 block has to be created, it is returned. */
3145 bsi_insert_on_edge_immediate (edge e
, tree stmt
)
3147 block_stmt_iterator bsi
;
3148 basic_block new_bb
= NULL
;
3150 gcc_assert (!PENDING_STMT (e
));
3152 if (tree_find_edge_insert_loc (e
, &bsi
, &new_bb
))
3153 bsi_insert_after (&bsi
, stmt
, BSI_NEW_STMT
);
3155 bsi_insert_before (&bsi
, stmt
, BSI_NEW_STMT
);
3160 /*---------------------------------------------------------------------------
3161 Tree specific functions for CFG manipulation
3162 ---------------------------------------------------------------------------*/
3164 /* Reinstall those PHI arguments queued in OLD_EDGE to NEW_EDGE. */
3167 reinstall_phi_args (edge new_edge
, edge old_edge
)
3171 if (!PENDING_STMT (old_edge
))
3174 for (var
= PENDING_STMT (old_edge
), phi
= phi_nodes (new_edge
->dest
);
3176 var
= TREE_CHAIN (var
), phi
= PHI_CHAIN (phi
))
3178 tree result
= TREE_PURPOSE (var
);
3179 tree arg
= TREE_VALUE (var
);
3181 gcc_assert (result
== PHI_RESULT (phi
));
3183 add_phi_arg (phi
, arg
, new_edge
);
3186 PENDING_STMT (old_edge
) = NULL
;
3189 /* Split a (typically critical) edge EDGE_IN. Return the new block.
3190 Abort on abnormal edges. */
3193 tree_split_edge (edge edge_in
)
3195 basic_block new_bb
, after_bb
, dest
, src
;
3198 /* Abnormal edges cannot be split. */
3199 gcc_assert (!(edge_in
->flags
& EDGE_ABNORMAL
));
3202 dest
= edge_in
->dest
;
3204 /* Place the new block in the block list. Try to keep the new block
3205 near its "logical" location. This is of most help to humans looking
3206 at debugging dumps. */
3207 if (dest
->prev_bb
&& find_edge (dest
->prev_bb
, dest
))
3208 after_bb
= edge_in
->src
;
3210 after_bb
= dest
->prev_bb
;
3212 new_bb
= create_empty_bb (after_bb
);
3213 new_bb
->frequency
= EDGE_FREQUENCY (edge_in
);
3214 new_bb
->count
= edge_in
->count
;
3215 new_edge
= make_edge (new_bb
, dest
, EDGE_FALLTHRU
);
3216 new_edge
->probability
= REG_BR_PROB_BASE
;
3217 new_edge
->count
= edge_in
->count
;
3219 e
= redirect_edge_and_branch (edge_in
, new_bb
);
3221 reinstall_phi_args (new_edge
, e
);
3227 /* Return true when BB has label LABEL in it. */
3230 has_label_p (basic_block bb
, tree label
)
3232 block_stmt_iterator bsi
;
3234 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
3236 tree stmt
= bsi_stmt (bsi
);
3238 if (TREE_CODE (stmt
) != LABEL_EXPR
)
3240 if (LABEL_EXPR_LABEL (stmt
) == label
)
3247 /* Callback for walk_tree, check that all elements with address taken are
3248 properly noticed as such. The DATA is an int* that is 1 if TP was seen
3249 inside a PHI node. */
3252 verify_expr (tree
*tp
, int *walk_subtrees
, void *data ATTRIBUTE_UNUSED
)
3255 bool in_phi
= (data
!= NULL
);
3260 /* Check operand N for being valid GIMPLE and give error MSG if not.
3261 We check for constants explicitly since they are not considered
3262 gimple invariants if they overflowed. */
3263 #define CHECK_OP(N, MSG) \
3264 do { if (!CONSTANT_CLASS_P (TREE_OPERAND (t, N)) \
3265 && !is_gimple_val (TREE_OPERAND (t, N))) \
3266 { error (MSG); return TREE_OPERAND (t, N); }} while (0)
3268 switch (TREE_CODE (t
))
3271 if (SSA_NAME_IN_FREE_LIST (t
))
3273 error ("SSA name in freelist but still referenced");
3279 x
= TREE_OPERAND (t
, 0);
3280 if (TREE_CODE (x
) == BIT_FIELD_REF
3281 && is_gimple_reg (TREE_OPERAND (x
, 0)))
3283 error ("GIMPLE register modified with BIT_FIELD_REF");
3289 /* ??? tree-ssa-alias.c may have overlooked dead PHI nodes, missing
3290 dead PHIs that take the address of something. But if the PHI
3291 result is dead, the fact that it takes the address of anything
3292 is irrelevant. Because we can not tell from here if a PHI result
3293 is dead, we just skip this check for PHIs altogether. This means
3294 we may be missing "valid" checks, but what can you do?
3295 This was PR19217. */
3299 /* Skip any references (they will be checked when we recurse down the
3300 tree) and ensure that any variable used as a prefix is marked
3302 for (x
= TREE_OPERAND (t
, 0);
3303 handled_component_p (x
);
3304 x
= TREE_OPERAND (x
, 0))
3307 if (TREE_CODE (x
) != VAR_DECL
&& TREE_CODE (x
) != PARM_DECL
)
3309 if (!TREE_ADDRESSABLE (x
))
3311 error ("address taken, but ADDRESSABLE bit not set");
3317 x
= COND_EXPR_COND (t
);
3318 if (TREE_CODE (TREE_TYPE (x
)) != BOOLEAN_TYPE
)
3320 error ("non-boolean used in condition");
3327 case FIX_TRUNC_EXPR
:
3329 case FIX_FLOOR_EXPR
:
3330 case FIX_ROUND_EXPR
:
3335 case NON_LVALUE_EXPR
:
3336 case TRUTH_NOT_EXPR
:
3337 CHECK_OP (0, "Invalid operand to unary operator");
3344 case ARRAY_RANGE_REF
:
3346 case VIEW_CONVERT_EXPR
:
3347 /* We have a nest of references. Verify that each of the operands
3348 that determine where to reference is either a constant or a variable,
3349 verify that the base is valid, and then show we've already checked
3351 while (handled_component_p (t
))
3353 if (TREE_CODE (t
) == COMPONENT_REF
&& TREE_OPERAND (t
, 2))
3354 CHECK_OP (2, "Invalid COMPONENT_REF offset operator");
3355 else if (TREE_CODE (t
) == ARRAY_REF
3356 || TREE_CODE (t
) == ARRAY_RANGE_REF
)
3358 CHECK_OP (1, "Invalid array index.");
3359 if (TREE_OPERAND (t
, 2))
3360 CHECK_OP (2, "Invalid array lower bound.");
3361 if (TREE_OPERAND (t
, 3))
3362 CHECK_OP (3, "Invalid array stride.");
3364 else if (TREE_CODE (t
) == BIT_FIELD_REF
)
3366 CHECK_OP (1, "Invalid operand to BIT_FIELD_REF");
3367 CHECK_OP (2, "Invalid operand to BIT_FIELD_REF");
3370 t
= TREE_OPERAND (t
, 0);
3373 if (!CONSTANT_CLASS_P (t
) && !is_gimple_lvalue (t
))
3375 error ("Invalid reference prefix.");
3387 case UNORDERED_EXPR
:
3398 case TRUNC_DIV_EXPR
:
3400 case FLOOR_DIV_EXPR
:
3401 case ROUND_DIV_EXPR
:
3402 case TRUNC_MOD_EXPR
:
3404 case FLOOR_MOD_EXPR
:
3405 case ROUND_MOD_EXPR
:
3407 case EXACT_DIV_EXPR
:
3417 CHECK_OP (0, "Invalid operand to binary operator");
3418 CHECK_OP (1, "Invalid operand to binary operator");
3430 /* Verify STMT, return true if STMT is not in GIMPLE form.
3431 TODO: Implement type checking. */
3434 verify_stmt (tree stmt
, bool last_in_block
)
3438 if (!is_gimple_stmt (stmt
))
3440 error ("Is not a valid GIMPLE statement.");
3444 addr
= walk_tree (&stmt
, verify_expr
, NULL
, NULL
);
3447 debug_generic_stmt (addr
);
3451 /* If the statement is marked as part of an EH region, then it is
3452 expected that the statement could throw. Verify that when we
3453 have optimizations that simplify statements such that we prove
3454 that they cannot throw, that we update other data structures
3456 if (lookup_stmt_eh_region (stmt
) >= 0)
3458 if (!tree_could_throw_p (stmt
))
3460 error ("Statement marked for throw, but doesn%'t.");
3463 if (!last_in_block
&& tree_can_throw_internal (stmt
))
3465 error ("Statement marked for throw in middle of block.");
3473 debug_generic_stmt (stmt
);
3478 /* Return true when the T can be shared. */
3481 tree_node_can_be_shared (tree t
)
3483 if (IS_TYPE_OR_DECL_P (t
)
3484 /* We check for constants explicitly since they are not considered
3485 gimple invariants if they overflowed. */
3486 || CONSTANT_CLASS_P (t
)
3487 || is_gimple_min_invariant (t
)
3488 || TREE_CODE (t
) == SSA_NAME
3489 || t
== error_mark_node
)
3492 if (TREE_CODE (t
) == CASE_LABEL_EXPR
)
3495 while (((TREE_CODE (t
) == ARRAY_REF
|| TREE_CODE (t
) == ARRAY_RANGE_REF
)
3496 /* We check for constants explicitly since they are not considered
3497 gimple invariants if they overflowed. */
3498 && (CONSTANT_CLASS_P (TREE_OPERAND (t
, 1))
3499 || is_gimple_min_invariant (TREE_OPERAND (t
, 1))))
3500 || (TREE_CODE (t
) == COMPONENT_REF
3501 || TREE_CODE (t
) == REALPART_EXPR
3502 || TREE_CODE (t
) == IMAGPART_EXPR
))
3503 t
= TREE_OPERAND (t
, 0);
3512 /* Called via walk_trees. Verify tree sharing. */
3515 verify_node_sharing (tree
* tp
, int *walk_subtrees
, void *data
)
3517 htab_t htab
= (htab_t
) data
;
3520 if (tree_node_can_be_shared (*tp
))
3522 *walk_subtrees
= false;
3526 slot
= htab_find_slot (htab
, *tp
, INSERT
);
3535 /* Verify the GIMPLE statement chain. */
3541 block_stmt_iterator bsi
;
3546 timevar_push (TV_TREE_STMT_VERIFY
);
3547 htab
= htab_create (37, htab_hash_pointer
, htab_eq_pointer
, NULL
);
3554 for (phi
= phi_nodes (bb
); phi
; phi
= PHI_CHAIN (phi
))
3556 int phi_num_args
= PHI_NUM_ARGS (phi
);
3558 for (i
= 0; i
< phi_num_args
; i
++)
3560 tree t
= PHI_ARG_DEF (phi
, i
);
3563 /* Addressable variables do have SSA_NAMEs but they
3564 are not considered gimple values. */
3565 if (TREE_CODE (t
) != SSA_NAME
3566 && TREE_CODE (t
) != FUNCTION_DECL
3567 && !is_gimple_val (t
))
3569 error ("PHI def is not a GIMPLE value");
3570 debug_generic_stmt (phi
);
3571 debug_generic_stmt (t
);
3575 addr
= walk_tree (&t
, verify_expr
, (void *) 1, NULL
);
3578 debug_generic_stmt (addr
);
3582 addr
= walk_tree (&t
, verify_node_sharing
, htab
, NULL
);
3585 error ("Incorrect sharing of tree nodes");
3586 debug_generic_stmt (phi
);
3587 debug_generic_stmt (addr
);
3593 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); )
3595 tree stmt
= bsi_stmt (bsi
);
3597 err
|= verify_stmt (stmt
, bsi_end_p (bsi
));
3598 addr
= walk_tree (&stmt
, verify_node_sharing
, htab
, NULL
);
3601 error ("Incorrect sharing of tree nodes");
3602 debug_generic_stmt (stmt
);
3603 debug_generic_stmt (addr
);
3610 internal_error ("verify_stmts failed.");
3613 timevar_pop (TV_TREE_STMT_VERIFY
);
3617 /* Verifies that the flow information is OK. */
3620 tree_verify_flow_info (void)
3624 block_stmt_iterator bsi
;
3629 if (ENTRY_BLOCK_PTR
->stmt_list
)
3631 error ("ENTRY_BLOCK has a statement list associated with it\n");
3635 if (EXIT_BLOCK_PTR
->stmt_list
)
3637 error ("EXIT_BLOCK has a statement list associated with it\n");
3641 FOR_EACH_EDGE (e
, ei
, EXIT_BLOCK_PTR
->preds
)
3642 if (e
->flags
& EDGE_FALLTHRU
)
3644 error ("Fallthru to exit from bb %d\n", e
->src
->index
);
3650 bool found_ctrl_stmt
= false;
3654 /* Skip labels on the start of basic block. */
3655 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
3657 tree prev_stmt
= stmt
;
3659 stmt
= bsi_stmt (bsi
);
3661 if (TREE_CODE (stmt
) != LABEL_EXPR
)
3664 if (prev_stmt
&& DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt
)))
3666 error ("Nonlocal label %s is not first "
3667 "in a sequence of labels in bb %d",
3668 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt
))),
3673 if (label_to_block (LABEL_EXPR_LABEL (stmt
)) != bb
)
3675 error ("Label %s to block does not match in bb %d\n",
3676 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt
))),
3681 if (decl_function_context (LABEL_EXPR_LABEL (stmt
))
3682 != current_function_decl
)
3684 error ("Label %s has incorrect context in bb %d\n",
3685 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt
))),
3691 /* Verify that body of basic block BB is free of control flow. */
3692 for (; !bsi_end_p (bsi
); bsi_next (&bsi
))
3694 tree stmt
= bsi_stmt (bsi
);
3696 if (found_ctrl_stmt
)
3698 error ("Control flow in the middle of basic block %d\n",
3703 if (stmt_ends_bb_p (stmt
))
3704 found_ctrl_stmt
= true;
3706 if (TREE_CODE (stmt
) == LABEL_EXPR
)
3708 error ("Label %s in the middle of basic block %d\n",
3709 IDENTIFIER_POINTER (DECL_NAME (stmt
)),
3714 bsi
= bsi_last (bb
);
3715 if (bsi_end_p (bsi
))
3718 stmt
= bsi_stmt (bsi
);
3720 if (is_ctrl_stmt (stmt
))
3722 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
3723 if (e
->flags
& EDGE_FALLTHRU
)
3725 error ("Fallthru edge after a control statement in bb %d \n",
3731 switch (TREE_CODE (stmt
))
3737 if (TREE_CODE (COND_EXPR_THEN (stmt
)) != GOTO_EXPR
3738 || TREE_CODE (COND_EXPR_ELSE (stmt
)) != GOTO_EXPR
)
3740 error ("Structured COND_EXPR at the end of bb %d\n", bb
->index
);
3744 extract_true_false_edges_from_block (bb
, &true_edge
, &false_edge
);
3746 if (!true_edge
|| !false_edge
3747 || !(true_edge
->flags
& EDGE_TRUE_VALUE
)
3748 || !(false_edge
->flags
& EDGE_FALSE_VALUE
)
3749 || (true_edge
->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
))
3750 || (false_edge
->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
))
3751 || EDGE_COUNT (bb
->succs
) >= 3)
3753 error ("Wrong outgoing edge flags at end of bb %d\n",
3758 if (!has_label_p (true_edge
->dest
,
3759 GOTO_DESTINATION (COND_EXPR_THEN (stmt
))))
3761 error ("%<then%> label does not match edge at end of bb %d\n",
3766 if (!has_label_p (false_edge
->dest
,
3767 GOTO_DESTINATION (COND_EXPR_ELSE (stmt
))))
3769 error ("%<else%> label does not match edge at end of bb %d\n",
3777 if (simple_goto_p (stmt
))
3779 error ("Explicit goto at end of bb %d\n", bb
->index
);
3784 /* FIXME. We should double check that the labels in the
3785 destination blocks have their address taken. */
3786 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
3787 if ((e
->flags
& (EDGE_FALLTHRU
| EDGE_TRUE_VALUE
3788 | EDGE_FALSE_VALUE
))
3789 || !(e
->flags
& EDGE_ABNORMAL
))
3791 error ("Wrong outgoing edge flags at end of bb %d\n",
3799 if (EDGE_COUNT (bb
->succs
) != 1
3800 || (EDGE_SUCC (bb
, 0)->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
3801 | EDGE_TRUE_VALUE
| EDGE_FALSE_VALUE
)))
3803 error ("Wrong outgoing edge flags at end of bb %d\n", bb
->index
);
3806 if (EDGE_SUCC (bb
, 0)->dest
!= EXIT_BLOCK_PTR
)
3808 error ("Return edge does not point to exit in bb %d\n",
3821 vec
= SWITCH_LABELS (stmt
);
3822 n
= TREE_VEC_LENGTH (vec
);
3824 /* Mark all the destination basic blocks. */
3825 for (i
= 0; i
< n
; ++i
)
3827 tree lab
= CASE_LABEL (TREE_VEC_ELT (vec
, i
));
3828 basic_block label_bb
= label_to_block (lab
);
3830 gcc_assert (!label_bb
->aux
|| label_bb
->aux
== (void *)1);
3831 label_bb
->aux
= (void *)1;
3834 /* Verify that the case labels are sorted. */
3835 prev
= TREE_VEC_ELT (vec
, 0);
3836 for (i
= 1; i
< n
- 1; ++i
)
3838 tree c
= TREE_VEC_ELT (vec
, i
);
3841 error ("Found default case not at end of case vector");
3845 if (! tree_int_cst_lt (CASE_LOW (prev
), CASE_LOW (c
)))
3847 error ("Case labels not sorted:\n ");
3848 print_generic_expr (stderr
, prev
, 0);
3849 fprintf (stderr
," is greater than ");
3850 print_generic_expr (stderr
, c
, 0);
3851 fprintf (stderr
," but comes before it.\n");
3856 if (CASE_LOW (TREE_VEC_ELT (vec
, n
- 1)))
3858 error ("No default case found at end of case vector");
3862 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
3866 error ("Extra outgoing edge %d->%d\n",
3867 bb
->index
, e
->dest
->index
);
3870 e
->dest
->aux
= (void *)2;
3871 if ((e
->flags
& (EDGE_FALLTHRU
| EDGE_ABNORMAL
3872 | EDGE_TRUE_VALUE
| EDGE_FALSE_VALUE
)))
3874 error ("Wrong outgoing edge flags at end of bb %d\n",
3880 /* Check that we have all of them. */
3881 for (i
= 0; i
< n
; ++i
)
3883 tree lab
= CASE_LABEL (TREE_VEC_ELT (vec
, i
));
3884 basic_block label_bb
= label_to_block (lab
);
3886 if (label_bb
->aux
!= (void *)2)
3888 error ("Missing edge %i->%i",
3889 bb
->index
, label_bb
->index
);
3894 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
3895 e
->dest
->aux
= (void *)0;
3902 if (dom_computed
[CDI_DOMINATORS
] >= DOM_NO_FAST_QUERY
)
3903 verify_dominators (CDI_DOMINATORS
);
3909 /* Updates phi nodes after creating a forwarder block joined
3910 by edge FALLTHRU. */
3913 tree_make_forwarder_block (edge fallthru
)
3917 basic_block dummy
, bb
;
3918 tree phi
, new_phi
, var
;
3920 dummy
= fallthru
->src
;
3921 bb
= fallthru
->dest
;
3923 if (EDGE_COUNT (bb
->preds
) == 1)
3926 /* If we redirected a branch we must create new phi nodes at the
3928 for (phi
= phi_nodes (dummy
); phi
; phi
= PHI_CHAIN (phi
))
3930 var
= PHI_RESULT (phi
);
3931 new_phi
= create_phi_node (var
, bb
);
3932 SSA_NAME_DEF_STMT (var
) = new_phi
;
3933 SET_PHI_RESULT (phi
, make_ssa_name (SSA_NAME_VAR (var
), phi
));
3934 add_phi_arg (new_phi
, PHI_RESULT (phi
), fallthru
);
3937 /* Ensure that the PHI node chain is in the same order. */
3938 set_phi_nodes (bb
, phi_reverse (phi_nodes (bb
)));
3940 /* Add the arguments we have stored on edges. */
3941 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
3946 flush_pending_stmts (e
);
3951 /* Return true if basic block BB does nothing except pass control
3952 flow to another block and that we can safely insert a label at
3953 the start of the successor block.
3955 As a precondition, we require that BB be not equal to
3959 tree_forwarder_block_p (basic_block bb
, bool phi_wanted
)
3961 block_stmt_iterator bsi
;
3963 /* BB must have a single outgoing edge. */
3964 if (EDGE_COUNT (bb
->succs
) != 1
3965 /* If PHI_WANTED is false, BB must not have any PHI nodes.
3966 Otherwise, BB must have PHI nodes. */
3967 || (phi_nodes (bb
) != NULL_TREE
) != phi_wanted
3968 /* BB may not be a predecessor of EXIT_BLOCK_PTR. */
3969 || EDGE_SUCC (bb
, 0)->dest
== EXIT_BLOCK_PTR
3970 /* Nor should this be an infinite loop. */
3971 || EDGE_SUCC (bb
, 0)->dest
== bb
3972 /* BB may not have an abnormal outgoing edge. */
3973 || (EDGE_SUCC (bb
, 0)->flags
& EDGE_ABNORMAL
))
3977 gcc_assert (bb
!= ENTRY_BLOCK_PTR
);
3980 /* Now walk through the statements backward. We can ignore labels,
3981 anything else means this is not a forwarder block. */
3982 for (bsi
= bsi_last (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
3984 tree stmt
= bsi_stmt (bsi
);
3986 switch (TREE_CODE (stmt
))
3989 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt
)))
3998 if (find_edge (ENTRY_BLOCK_PTR
, bb
))
4004 /* Return true if BB has at least one abnormal incoming edge. */
4007 has_abnormal_incoming_edge_p (basic_block bb
)
4012 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
4013 if (e
->flags
& EDGE_ABNORMAL
)
4019 /* Removes forwarder block BB. Returns false if this failed. If a new
4020 forwarder block is created due to redirection of edges, it is
4021 stored to worklist. */
4024 remove_forwarder_block (basic_block bb
, basic_block
**worklist
)
4026 edge succ
= EDGE_SUCC (bb
, 0), e
, s
;
4027 basic_block dest
= succ
->dest
;
4031 block_stmt_iterator bsi
, bsi_to
;
4032 bool seen_abnormal_edge
= false;
4034 /* We check for infinite loops already in tree_forwarder_block_p.
4035 However it may happen that the infinite loop is created
4036 afterwards due to removal of forwarders. */
4040 /* If the destination block consists of a nonlocal label, do not merge
4042 label
= first_stmt (dest
);
4044 && TREE_CODE (label
) == LABEL_EXPR
4045 && DECL_NONLOCAL (LABEL_EXPR_LABEL (label
)))
4048 /* If there is an abnormal edge to basic block BB, but not into
4049 dest, problems might occur during removal of the phi node at out
4050 of ssa due to overlapping live ranges of registers.
4052 If there is an abnormal edge in DEST, the problems would occur
4053 anyway since cleanup_dead_labels would then merge the labels for
4054 two different eh regions, and rest of exception handling code
4057 So if there is an abnormal edge to BB, proceed only if there is
4058 no abnormal edge to DEST and there are no phi nodes in DEST. */
4059 if (has_abnormal_incoming_edge_p (bb
))
4061 seen_abnormal_edge
= true;
4063 if (has_abnormal_incoming_edge_p (dest
)
4064 || phi_nodes (dest
) != NULL_TREE
)
4068 /* If there are phi nodes in DEST, and some of the blocks that are
4069 predecessors of BB are also predecessors of DEST, check that the
4070 phi node arguments match. */
4071 if (phi_nodes (dest
))
4073 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
4075 s
= find_edge (e
->src
, dest
);
4079 if (!phi_alternatives_equal (dest
, succ
, s
))
4084 /* Redirect the edges. */
4085 for (ei
= ei_start (bb
->preds
); (e
= ei_safe_edge (ei
)); )
4087 if (e
->flags
& EDGE_ABNORMAL
)
4089 /* If there is an abnormal edge, redirect it anyway, and
4090 move the labels to the new block to make it legal. */
4091 s
= redirect_edge_succ_nodup (e
, dest
);
4094 s
= redirect_edge_and_branch (e
, dest
);
4098 /* Create arguments for the phi nodes, since the edge was not
4100 for (phi
= phi_nodes (dest
); phi
; phi
= PHI_CHAIN (phi
))
4101 add_phi_arg (phi
, PHI_ARG_DEF (phi
, succ
->dest_idx
), s
);
4105 /* The source basic block might become a forwarder. We know
4106 that it was not a forwarder before, since it used to have
4107 at least two outgoing edges, so we may just add it to
4109 if (tree_forwarder_block_p (s
->src
, false))
4110 *(*worklist
)++ = s
->src
;
4114 if (seen_abnormal_edge
)
4116 /* Move the labels to the new block, so that the redirection of
4117 the abnormal edges works. */
4119 bsi_to
= bsi_start (dest
);
4120 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); )
4122 label
= bsi_stmt (bsi
);
4123 gcc_assert (TREE_CODE (label
) == LABEL_EXPR
);
4125 bsi_insert_before (&bsi_to
, label
, BSI_CONTINUE_LINKING
);
4129 /* Update the dominators. */
4130 if (dom_info_available_p (CDI_DOMINATORS
))
4132 basic_block dom
, dombb
, domdest
;
4134 dombb
= get_immediate_dominator (CDI_DOMINATORS
, bb
);
4135 domdest
= get_immediate_dominator (CDI_DOMINATORS
, dest
);
4138 /* Shortcut to avoid calling (relatively expensive)
4139 nearest_common_dominator unless necessary. */
4143 dom
= nearest_common_dominator (CDI_DOMINATORS
, domdest
, dombb
);
4145 set_immediate_dominator (CDI_DOMINATORS
, dest
, dom
);
4148 /* And kill the forwarder block. */
4149 delete_basic_block (bb
);
4154 /* Removes forwarder blocks. */
4157 cleanup_forwarder_blocks (void)
4160 bool changed
= false;
4161 basic_block
*worklist
= xmalloc (sizeof (basic_block
) * n_basic_blocks
);
4162 basic_block
*current
= worklist
;
4166 if (tree_forwarder_block_p (bb
, false))
4170 while (current
!= worklist
)
4173 changed
|= remove_forwarder_block (bb
, ¤t
);
4180 /* Merge the PHI nodes at BB into those at BB's sole successor. */
4183 remove_forwarder_block_with_phi (basic_block bb
)
4185 edge succ
= EDGE_SUCC (bb
, 0);
4186 basic_block dest
= succ
->dest
;
4188 basic_block dombb
, domdest
, dom
;
4190 /* We check for infinite loops already in tree_forwarder_block_p.
4191 However it may happen that the infinite loop is created
4192 afterwards due to removal of forwarders. */
4196 /* If the destination block consists of a nonlocal label, do not
4198 label
= first_stmt (dest
);
4200 && TREE_CODE (label
) == LABEL_EXPR
4201 && DECL_NONLOCAL (LABEL_EXPR_LABEL (label
)))
4204 /* Redirect each incoming edge to BB to DEST. */
4205 while (EDGE_COUNT (bb
->preds
) > 0)
4207 edge e
= EDGE_PRED (bb
, 0), s
;
4210 s
= find_edge (e
->src
, dest
);
4213 /* We already have an edge S from E->src to DEST. If S and
4214 E->dest's sole successor edge have the same PHI arguments
4215 at DEST, redirect S to DEST. */
4216 if (phi_alternatives_equal (dest
, s
, succ
))
4218 e
= redirect_edge_and_branch (e
, dest
);
4219 PENDING_STMT (e
) = NULL_TREE
;
4223 /* PHI arguments are different. Create a forwarder block by
4224 splitting E so that we can merge PHI arguments on E to
4226 e
= EDGE_SUCC (split_edge (e
), 0);
4229 s
= redirect_edge_and_branch (e
, dest
);
4231 /* redirect_edge_and_branch must not create a new edge. */
4232 gcc_assert (s
== e
);
4234 /* Add to the PHI nodes at DEST each PHI argument removed at the
4235 destination of E. */
4236 for (phi
= phi_nodes (dest
); phi
; phi
= PHI_CHAIN (phi
))
4238 tree def
= PHI_ARG_DEF (phi
, succ
->dest_idx
);
4240 if (TREE_CODE (def
) == SSA_NAME
)
4244 /* If DEF is one of the results of PHI nodes removed during
4245 redirection, replace it with the PHI argument that used
4247 for (var
= PENDING_STMT (e
); var
; var
= TREE_CHAIN (var
))
4249 tree old_arg
= TREE_PURPOSE (var
);
4250 tree new_arg
= TREE_VALUE (var
);
4260 add_phi_arg (phi
, def
, s
);
4263 PENDING_STMT (e
) = NULL
;
4266 /* Update the dominators. */
4267 dombb
= get_immediate_dominator (CDI_DOMINATORS
, bb
);
4268 domdest
= get_immediate_dominator (CDI_DOMINATORS
, dest
);
4271 /* Shortcut to avoid calling (relatively expensive)
4272 nearest_common_dominator unless necessary. */
4276 dom
= nearest_common_dominator (CDI_DOMINATORS
, domdest
, dombb
);
4278 set_immediate_dominator (CDI_DOMINATORS
, dest
, dom
);
4280 /* Remove BB since all of BB's incoming edges have been redirected
4282 delete_basic_block (bb
);
4285 /* This pass merges PHI nodes if one feeds into another. For example,
4286 suppose we have the following:
4293 # tem_6 = PHI <tem_17(8), tem_23(7)>;
4296 # tem_3 = PHI <tem_6(9), tem_2(5)>;
4299 Then we merge the first PHI node into the second one like so:
4301 goto <bb 9> (<L10>);
4306 # tem_3 = PHI <tem_23(7), tem_2(5), tem_17(8)>;
4311 merge_phi_nodes (void)
4313 basic_block
*worklist
= xmalloc (sizeof (basic_block
) * n_basic_blocks
);
4314 basic_block
*current
= worklist
;
4317 calculate_dominance_info (CDI_DOMINATORS
);
4319 /* Find all PHI nodes that we may be able to merge. */
4324 /* Look for a forwarder block with PHI nodes. */
4325 if (!tree_forwarder_block_p (bb
, true))
4328 dest
= EDGE_SUCC (bb
, 0)->dest
;
4330 /* We have to feed into another basic block with PHI
4332 if (!phi_nodes (dest
)
4333 /* We don't want to deal with a basic block with
4335 || has_abnormal_incoming_edge_p (bb
))
4338 if (!dominated_by_p (CDI_DOMINATORS
, dest
, bb
))
4340 /* If BB does not dominate DEST, then the PHI nodes at
4341 DEST must be the only users of the results of the PHI
4347 /* Now let's drain WORKLIST. */
4348 while (current
!= worklist
)
4351 remove_forwarder_block_with_phi (bb
);
4358 gate_merge_phi (void)
4363 struct tree_opt_pass pass_merge_phi
= {
4364 "mergephi", /* name */
4365 gate_merge_phi
, /* gate */
4366 merge_phi_nodes
, /* execute */
4369 0, /* static_pass_number */
4370 TV_TREE_MERGE_PHI
, /* tv_id */
4371 PROP_cfg
| PROP_ssa
, /* properties_required */
4372 0, /* properties_provided */
4373 0, /* properties_destroyed */
4374 0, /* todo_flags_start */
4375 TODO_dump_func
| TODO_ggc_collect
/* todo_flags_finish */
4380 /* Return a non-special label in the head of basic block BLOCK.
4381 Create one if it doesn't exist. */
4384 tree_block_label (basic_block bb
)
4386 block_stmt_iterator i
, s
= bsi_start (bb
);
4390 for (i
= s
; !bsi_end_p (i
); first
= false, bsi_next (&i
))
4392 stmt
= bsi_stmt (i
);
4393 if (TREE_CODE (stmt
) != LABEL_EXPR
)
4395 label
= LABEL_EXPR_LABEL (stmt
);
4396 if (!DECL_NONLOCAL (label
))
4399 bsi_move_before (&i
, &s
);
4404 label
= create_artificial_label ();
4405 stmt
= build1 (LABEL_EXPR
, void_type_node
, label
);
4406 bsi_insert_before (&s
, stmt
, BSI_NEW_STMT
);
4411 /* Attempt to perform edge redirection by replacing a possibly complex
4412 jump instruction by a goto or by removing the jump completely.
4413 This can apply only if all edges now point to the same block. The
4414 parameters and return values are equivalent to
4415 redirect_edge_and_branch. */
4418 tree_try_redirect_by_replacing_jump (edge e
, basic_block target
)
4420 basic_block src
= e
->src
;
4421 block_stmt_iterator b
;
4424 /* We can replace or remove a complex jump only when we have exactly
4426 if (EDGE_COUNT (src
->succs
) != 2
4427 /* Verify that all targets will be TARGET. Specifically, the
4428 edge that is not E must also go to TARGET. */
4429 || EDGE_SUCC (src
, EDGE_SUCC (src
, 0) == e
)->dest
!= target
)
4435 stmt
= bsi_stmt (b
);
4437 if (TREE_CODE (stmt
) == COND_EXPR
4438 || TREE_CODE (stmt
) == SWITCH_EXPR
)
4441 e
= ssa_redirect_edge (e
, target
);
4442 e
->flags
= EDGE_FALLTHRU
;
4450 /* Redirect E to DEST. Return NULL on failure. Otherwise, return the
4451 edge representing the redirected branch. */
4454 tree_redirect_edge_and_branch (edge e
, basic_block dest
)
4456 basic_block bb
= e
->src
;
4457 block_stmt_iterator bsi
;
4461 if (e
->flags
& (EDGE_ABNORMAL_CALL
| EDGE_EH
))
4464 if (e
->src
!= ENTRY_BLOCK_PTR
4465 && (ret
= tree_try_redirect_by_replacing_jump (e
, dest
)))
4468 if (e
->dest
== dest
)
4471 label
= tree_block_label (dest
);
4473 bsi
= bsi_last (bb
);
4474 stmt
= bsi_end_p (bsi
) ? NULL
: bsi_stmt (bsi
);
4476 switch (stmt
? TREE_CODE (stmt
) : ERROR_MARK
)
4479 stmt
= (e
->flags
& EDGE_TRUE_VALUE
4480 ? COND_EXPR_THEN (stmt
)
4481 : COND_EXPR_ELSE (stmt
));
4482 GOTO_DESTINATION (stmt
) = label
;
4486 /* No non-abnormal edges should lead from a non-simple goto, and
4487 simple ones should be represented implicitly. */
4492 tree cases
= get_cases_for_edge (e
, stmt
);
4494 /* If we have a list of cases associated with E, then use it
4495 as it's a lot faster than walking the entire case vector. */
4498 edge e2
= find_edge (e
->src
, dest
);
4505 CASE_LABEL (cases
) = label
;
4506 cases
= TREE_CHAIN (cases
);
4509 /* If there was already an edge in the CFG, then we need
4510 to move all the cases associated with E to E2. */
4513 tree cases2
= get_cases_for_edge (e2
, stmt
);
4515 TREE_CHAIN (last
) = TREE_CHAIN (cases2
);
4516 TREE_CHAIN (cases2
) = first
;
4521 tree vec
= SWITCH_LABELS (stmt
);
4522 size_t i
, n
= TREE_VEC_LENGTH (vec
);
4524 for (i
= 0; i
< n
; i
++)
4526 tree elt
= TREE_VEC_ELT (vec
, i
);
4528 if (label_to_block (CASE_LABEL (elt
)) == e
->dest
)
4529 CASE_LABEL (elt
) = label
;
4538 e
->flags
|= EDGE_FALLTHRU
;
4542 /* Otherwise it must be a fallthru edge, and we don't need to
4543 do anything besides redirecting it. */
4544 gcc_assert (e
->flags
& EDGE_FALLTHRU
);
4548 /* Update/insert PHI nodes as necessary. */
4550 /* Now update the edges in the CFG. */
4551 e
= ssa_redirect_edge (e
, dest
);
4557 /* Simple wrapper, as we can always redirect fallthru edges. */
4560 tree_redirect_edge_and_branch_force (edge e
, basic_block dest
)
4562 e
= tree_redirect_edge_and_branch (e
, dest
);
4569 /* Splits basic block BB after statement STMT (but at least after the
4570 labels). If STMT is NULL, BB is split just after the labels. */
4573 tree_split_block (basic_block bb
, void *stmt
)
4575 block_stmt_iterator bsi
, bsi_tgt
;
4581 new_bb
= create_empty_bb (bb
);
4583 /* Redirect the outgoing edges. */
4584 new_bb
->succs
= bb
->succs
;
4586 FOR_EACH_EDGE (e
, ei
, new_bb
->succs
)
4589 if (stmt
&& TREE_CODE ((tree
) stmt
) == LABEL_EXPR
)
4592 /* Move everything from BSI to the new basic block. */
4593 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
4595 act
= bsi_stmt (bsi
);
4596 if (TREE_CODE (act
) == LABEL_EXPR
)
4609 bsi_tgt
= bsi_start (new_bb
);
4610 while (!bsi_end_p (bsi
))
4612 act
= bsi_stmt (bsi
);
4614 bsi_insert_after (&bsi_tgt
, act
, BSI_NEW_STMT
);
4621 /* Moves basic block BB after block AFTER. */
4624 tree_move_block_after (basic_block bb
, basic_block after
)
4626 if (bb
->prev_bb
== after
)
4630 link_block (bb
, after
);
4636 /* Return true if basic_block can be duplicated. */
4639 tree_can_duplicate_bb_p (basic_block bb ATTRIBUTE_UNUSED
)
4644 /* Create a duplicate of the basic block BB. NOTE: This does not
4645 preserve SSA form. */
4648 tree_duplicate_bb (basic_block bb
)
4651 block_stmt_iterator bsi
, bsi_tgt
;
4653 ssa_op_iter op_iter
;
4655 new_bb
= create_empty_bb (EXIT_BLOCK_PTR
->prev_bb
);
4657 /* First copy the phi nodes. We do not copy phi node arguments here,
4658 since the edges are not ready yet. Keep the chain of phi nodes in
4659 the same order, so that we can add them later. */
4660 for (phi
= phi_nodes (bb
); phi
; phi
= PHI_CHAIN (phi
))
4662 mark_for_rewrite (PHI_RESULT (phi
));
4663 create_phi_node (PHI_RESULT (phi
), new_bb
);
4665 set_phi_nodes (new_bb
, phi_reverse (phi_nodes (new_bb
)));
4667 bsi_tgt
= bsi_start (new_bb
);
4668 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
4670 tree stmt
= bsi_stmt (bsi
);
4673 if (TREE_CODE (stmt
) == LABEL_EXPR
)
4676 /* Record the definitions. */
4677 get_stmt_operands (stmt
);
4679 FOR_EACH_SSA_TREE_OPERAND (val
, stmt
, op_iter
, SSA_OP_ALL_DEFS
)
4680 mark_for_rewrite (val
);
4682 copy
= unshare_expr (stmt
);
4684 /* Copy also the virtual operands. */
4685 get_stmt_ann (copy
);
4686 copy_virtual_operands (copy
, stmt
);
4688 bsi_insert_after (&bsi_tgt
, copy
, BSI_NEW_STMT
);
4694 /* Basic block BB_COPY was created by code duplication. Add phi node
4695 arguments for edges going out of BB_COPY. The blocks that were
4696 duplicated have rbi->duplicated set to one. */
4699 add_phi_args_after_copy_bb (basic_block bb_copy
)
4701 basic_block bb
, dest
;
4704 tree phi
, phi_copy
, phi_next
, def
;
4706 bb
= bb_copy
->rbi
->original
;
4708 FOR_EACH_EDGE (e_copy
, ei
, bb_copy
->succs
)
4710 if (!phi_nodes (e_copy
->dest
))
4713 if (e_copy
->dest
->rbi
->duplicated
)
4714 dest
= e_copy
->dest
->rbi
->original
;
4716 dest
= e_copy
->dest
;
4718 e
= find_edge (bb
, dest
);
4721 /* During loop unrolling the target of the latch edge is copied.
4722 In this case we are not looking for edge to dest, but to
4723 duplicated block whose original was dest. */
4724 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
4725 if (e
->dest
->rbi
->duplicated
4726 && e
->dest
->rbi
->original
== dest
)
4729 gcc_assert (e
!= NULL
);
4732 for (phi
= phi_nodes (e
->dest
), phi_copy
= phi_nodes (e_copy
->dest
);
4734 phi
= phi_next
, phi_copy
= PHI_CHAIN (phi_copy
))
4736 phi_next
= PHI_CHAIN (phi
);
4738 gcc_assert (PHI_RESULT (phi
) == PHI_RESULT (phi_copy
));
4739 def
= PHI_ARG_DEF_FROM_EDGE (phi
, e
);
4740 add_phi_arg (phi_copy
, def
, e_copy
);
4745 /* Blocks in REGION_COPY array of length N_REGION were created by
4746 duplication of basic blocks. Add phi node arguments for edges
4747 going from these blocks. */
4750 add_phi_args_after_copy (basic_block
*region_copy
, unsigned n_region
)
4754 for (i
= 0; i
< n_region
; i
++)
4755 region_copy
[i
]->rbi
->duplicated
= 1;
4757 for (i
= 0; i
< n_region
; i
++)
4758 add_phi_args_after_copy_bb (region_copy
[i
]);
4760 for (i
= 0; i
< n_region
; i
++)
4761 region_copy
[i
]->rbi
->duplicated
= 0;
4764 /* Maps the old ssa name FROM_NAME to TO_NAME. */
4766 struct ssa_name_map_entry
4772 /* Hash function for ssa_name_map_entry. */
4775 ssa_name_map_entry_hash (const void *entry
)
4777 const struct ssa_name_map_entry
*en
= entry
;
4778 return SSA_NAME_VERSION (en
->from_name
);
4781 /* Equality function for ssa_name_map_entry. */
4784 ssa_name_map_entry_eq (const void *in_table
, const void *ssa_name
)
4786 const struct ssa_name_map_entry
*en
= in_table
;
4788 return en
->from_name
== ssa_name
;
4791 /* Allocate duplicates of ssa names in list DEFINITIONS and store the mapping
4795 allocate_ssa_names (bitmap definitions
, htab_t
*map
)
4798 struct ssa_name_map_entry
*entry
;
4804 *map
= htab_create (10, ssa_name_map_entry_hash
,
4805 ssa_name_map_entry_eq
, free
);
4806 EXECUTE_IF_SET_IN_BITMAP (definitions
, 0, ver
, bi
)
4808 name
= ssa_name (ver
);
4809 slot
= htab_find_slot_with_hash (*map
, name
, SSA_NAME_VERSION (name
),
4815 entry
= xmalloc (sizeof (struct ssa_name_map_entry
));
4816 entry
->from_name
= name
;
4819 entry
->to_name
= duplicate_ssa_name (name
, SSA_NAME_DEF_STMT (name
));
4823 /* Rewrite the definition DEF in statement STMT to new ssa name as specified
4824 by the mapping MAP. */
4827 rewrite_to_new_ssa_names_def (def_operand_p def
, tree stmt
, htab_t map
)
4829 tree name
= DEF_FROM_PTR (def
);
4830 struct ssa_name_map_entry
*entry
;
4832 gcc_assert (TREE_CODE (name
) == SSA_NAME
);
4834 entry
= htab_find_with_hash (map
, name
, SSA_NAME_VERSION (name
));
4838 SET_DEF (def
, entry
->to_name
);
4839 SSA_NAME_DEF_STMT (entry
->to_name
) = stmt
;
4842 /* Rewrite the USE to new ssa name as specified by the mapping MAP. */
4845 rewrite_to_new_ssa_names_use (use_operand_p use
, htab_t map
)
4847 tree name
= USE_FROM_PTR (use
);
4848 struct ssa_name_map_entry
*entry
;
4850 if (TREE_CODE (name
) != SSA_NAME
)
4853 entry
= htab_find_with_hash (map
, name
, SSA_NAME_VERSION (name
));
4857 SET_USE (use
, entry
->to_name
);
4860 /* Rewrite the ssa names in basic block BB to new ones as specified by the
4864 rewrite_to_new_ssa_names_bb (basic_block bb
, htab_t map
)
4870 block_stmt_iterator bsi
;
4874 v_may_def_optype v_may_defs
;
4875 v_must_def_optype v_must_defs
;
4878 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
4879 if (e
->flags
& EDGE_ABNORMAL
)
4882 for (phi
= phi_nodes (bb
); phi
; phi
= PHI_CHAIN (phi
))
4884 rewrite_to_new_ssa_names_def (PHI_RESULT_PTR (phi
), phi
, map
);
4886 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (PHI_RESULT (phi
)) = 1;
4889 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
4891 stmt
= bsi_stmt (bsi
);
4892 get_stmt_operands (stmt
);
4893 ann
= stmt_ann (stmt
);
4895 uses
= USE_OPS (ann
);
4896 for (i
= 0; i
< NUM_USES (uses
); i
++)
4897 rewrite_to_new_ssa_names_use (USE_OP_PTR (uses
, i
), map
);
4899 defs
= DEF_OPS (ann
);
4900 for (i
= 0; i
< NUM_DEFS (defs
); i
++)
4901 rewrite_to_new_ssa_names_def (DEF_OP_PTR (defs
, i
), stmt
, map
);
4903 vuses
= VUSE_OPS (ann
);
4904 for (i
= 0; i
< NUM_VUSES (vuses
); i
++)
4905 rewrite_to_new_ssa_names_use (VUSE_OP_PTR (vuses
, i
), map
);
4907 v_may_defs
= V_MAY_DEF_OPS (ann
);
4908 for (i
= 0; i
< NUM_V_MAY_DEFS (v_may_defs
); i
++)
4910 rewrite_to_new_ssa_names_use
4911 (V_MAY_DEF_OP_PTR (v_may_defs
, i
), map
);
4912 rewrite_to_new_ssa_names_def
4913 (V_MAY_DEF_RESULT_PTR (v_may_defs
, i
), stmt
, map
);
4916 v_must_defs
= V_MUST_DEF_OPS (ann
);
4917 for (i
= 0; i
< NUM_V_MUST_DEFS (v_must_defs
); i
++)
4919 rewrite_to_new_ssa_names_def
4920 (V_MUST_DEF_RESULT_PTR (v_must_defs
, i
), stmt
, map
);
4921 rewrite_to_new_ssa_names_use
4922 (V_MUST_DEF_KILL_PTR (v_must_defs
, i
), map
);
4926 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
4927 for (phi
= phi_nodes (e
->dest
); phi
; phi
= PHI_CHAIN (phi
))
4929 rewrite_to_new_ssa_names_use
4930 (PHI_ARG_DEF_PTR_FROM_EDGE (phi
, e
), map
);
4932 if (e
->flags
& EDGE_ABNORMAL
)
4934 tree op
= PHI_ARG_DEF_FROM_EDGE (phi
, e
);
4935 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op
) = 1;
4940 /* Rewrite the ssa names in N_REGION blocks REGION to the new ones as specified
4941 by the mapping MAP. */
4944 rewrite_to_new_ssa_names (basic_block
*region
, unsigned n_region
, htab_t map
)
4948 for (r
= 0; r
< n_region
; r
++)
4949 rewrite_to_new_ssa_names_bb (region
[r
], map
);
4952 /* Duplicates a REGION (set of N_REGION basic blocks) with just a single
4953 important exit edge EXIT. By important we mean that no SSA name defined
4954 inside region is live over the other exit edges of the region. All entry
4955 edges to the region must go to ENTRY->dest. The edge ENTRY is redirected
4956 to the duplicate of the region. SSA form, dominance and loop information
4957 is updated. The new basic blocks are stored to REGION_COPY in the same
4958 order as they had in REGION, provided that REGION_COPY is not NULL.
4959 The function returns false if it is unable to copy the region,
4963 tree_duplicate_sese_region (edge entry
, edge exit
,
4964 basic_block
*region
, unsigned n_region
,
4965 basic_block
*region_copy
)
4967 unsigned i
, n_doms
, ver
;
4968 bool free_region_copy
= false, copying_header
= false;
4969 struct loop
*loop
= entry
->dest
->loop_father
;
4974 htab_t ssa_name_map
= NULL
;
4978 if (!can_copy_bbs_p (region
, n_region
))
4981 /* Some sanity checking. Note that we do not check for all possible
4982 missuses of the functions. I.e. if you ask to copy something weird,
4983 it will work, but the state of structures probably will not be
4986 for (i
= 0; i
< n_region
; i
++)
4988 /* We do not handle subloops, i.e. all the blocks must belong to the
4990 if (region
[i
]->loop_father
!= loop
)
4993 if (region
[i
] != entry
->dest
4994 && region
[i
] == loop
->header
)
5000 /* In case the function is used for loop header copying (which is the primary
5001 use), ensure that EXIT and its copy will be new latch and entry edges. */
5002 if (loop
->header
== entry
->dest
)
5004 copying_header
= true;
5005 loop
->copy
= loop
->outer
;
5007 if (!dominated_by_p (CDI_DOMINATORS
, loop
->latch
, exit
->src
))
5010 for (i
= 0; i
< n_region
; i
++)
5011 if (region
[i
] != exit
->src
5012 && dominated_by_p (CDI_DOMINATORS
, region
[i
], exit
->src
))
5018 region_copy
= xmalloc (sizeof (basic_block
) * n_region
);
5019 free_region_copy
= true;
5022 gcc_assert (!any_marked_for_rewrite_p ());
5024 /* Record blocks outside the region that are duplicated by something
5026 doms
= xmalloc (sizeof (basic_block
) * n_basic_blocks
);
5027 n_doms
= get_dominated_by_region (CDI_DOMINATORS
, region
, n_region
, doms
);
5029 copy_bbs (region
, n_region
, region_copy
, &exit
, 1, &exit_copy
, loop
);
5030 definitions
= marked_ssa_names ();
5034 loop
->header
= exit
->dest
;
5035 loop
->latch
= exit
->src
;
5038 /* Redirect the entry and add the phi node arguments. */
5039 redirected
= redirect_edge_and_branch (entry
, entry
->dest
->rbi
->copy
);
5040 gcc_assert (redirected
!= NULL
);
5041 flush_pending_stmts (entry
);
5043 /* Concerning updating of dominators: We must recount dominators
5044 for entry block and its copy. Anything that is outside of the region, but
5045 was dominated by something inside needs recounting as well. */
5046 set_immediate_dominator (CDI_DOMINATORS
, entry
->dest
, entry
->src
);
5047 doms
[n_doms
++] = entry
->dest
->rbi
->original
;
5048 iterate_fix_dominators (CDI_DOMINATORS
, doms
, n_doms
);
5051 /* Add the other phi node arguments. */
5052 add_phi_args_after_copy (region_copy
, n_region
);
5054 /* Add phi nodes for definitions at exit. TODO -- once we have immediate
5055 uses, it should be possible to emit phi nodes just for definitions that
5056 are used outside region. */
5057 EXECUTE_IF_SET_IN_BITMAP (definitions
, 0, ver
, bi
)
5059 tree name
= ssa_name (ver
);
5061 phi
= create_phi_node (name
, exit
->dest
);
5062 add_phi_arg (phi
, name
, exit
);
5063 add_phi_arg (phi
, name
, exit_copy
);
5065 SSA_NAME_DEF_STMT (name
) = phi
;
5068 /* And create new definitions inside region and its copy. TODO -- once we
5069 have immediate uses, it might be better to leave definitions in region
5070 unchanged, create new ssa names for phi nodes on exit, and rewrite
5071 the uses, to avoid changing the copied region. */
5072 allocate_ssa_names (definitions
, &ssa_name_map
);
5073 rewrite_to_new_ssa_names (region
, n_region
, ssa_name_map
);
5074 allocate_ssa_names (definitions
, &ssa_name_map
);
5075 rewrite_to_new_ssa_names (region_copy
, n_region
, ssa_name_map
);
5076 htab_delete (ssa_name_map
);
5078 if (free_region_copy
)
5081 unmark_all_for_rewrite ();
5082 BITMAP_XFREE (definitions
);
5087 /* Dump FUNCTION_DECL FN to file FILE using FLAGS (see TDF_* in tree.h) */
5090 dump_function_to_file (tree fn
, FILE *file
, int flags
)
5092 tree arg
, vars
, var
;
5093 bool ignore_topmost_bind
= false, any_var
= false;
5097 fprintf (file
, "%s (", lang_hooks
.decl_printable_name (fn
, 2));
5099 arg
= DECL_ARGUMENTS (fn
);
5102 print_generic_expr (file
, arg
, dump_flags
);
5103 if (TREE_CHAIN (arg
))
5104 fprintf (file
, ", ");
5105 arg
= TREE_CHAIN (arg
);
5107 fprintf (file
, ")\n");
5109 if (flags
& TDF_RAW
)
5111 dump_node (fn
, TDF_SLIM
| flags
, file
);
5115 /* When GIMPLE is lowered, the variables are no longer available in
5116 BIND_EXPRs, so display them separately. */
5117 if (cfun
&& cfun
->unexpanded_var_list
)
5119 ignore_topmost_bind
= true;
5121 fprintf (file
, "{\n");
5122 for (vars
= cfun
->unexpanded_var_list
; vars
; vars
= TREE_CHAIN (vars
))
5124 var
= TREE_VALUE (vars
);
5126 print_generic_decl (file
, var
, flags
);
5127 fprintf (file
, "\n");
5133 if (basic_block_info
)
5135 /* Make a CFG based dump. */
5136 check_bb_profile (ENTRY_BLOCK_PTR
, file
);
5137 if (!ignore_topmost_bind
)
5138 fprintf (file
, "{\n");
5140 if (any_var
&& n_basic_blocks
)
5141 fprintf (file
, "\n");
5144 dump_generic_bb (file
, bb
, 2, flags
);
5146 fprintf (file
, "}\n");
5147 check_bb_profile (EXIT_BLOCK_PTR
, file
);
5153 /* Make a tree based dump. */
5154 chain
= DECL_SAVED_TREE (fn
);
5156 if (TREE_CODE (chain
) == BIND_EXPR
)
5158 if (ignore_topmost_bind
)
5160 chain
= BIND_EXPR_BODY (chain
);
5168 if (!ignore_topmost_bind
)
5169 fprintf (file
, "{\n");
5174 fprintf (file
, "\n");
5176 print_generic_stmt_indented (file
, chain
, flags
, indent
);
5177 if (ignore_topmost_bind
)
5178 fprintf (file
, "}\n");
5181 fprintf (file
, "\n\n");
5185 /* Pretty print of the loops intermediate representation. */
5186 static void print_loop (FILE *, struct loop
*, int);
5187 static void print_pred_bbs (FILE *, basic_block bb
);
5188 static void print_succ_bbs (FILE *, basic_block bb
);
5191 /* Print the predecessors indexes of edge E on FILE. */
5194 print_pred_bbs (FILE *file
, basic_block bb
)
5199 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
5200 fprintf (file
, "bb_%d", e
->src
->index
);
5204 /* Print the successors indexes of edge E on FILE. */
5207 print_succ_bbs (FILE *file
, basic_block bb
)
5212 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
5213 fprintf (file
, "bb_%d", e
->src
->index
);
5217 /* Pretty print LOOP on FILE, indented INDENT spaces. */
5220 print_loop (FILE *file
, struct loop
*loop
, int indent
)
5228 s_indent
= (char *) alloca ((size_t) indent
+ 1);
5229 memset ((void *) s_indent
, ' ', (size_t) indent
);
5230 s_indent
[indent
] = '\0';
5232 /* Print the loop's header. */
5233 fprintf (file
, "%sloop_%d\n", s_indent
, loop
->num
);
5235 /* Print the loop's body. */
5236 fprintf (file
, "%s{\n", s_indent
);
5238 if (bb
->loop_father
== loop
)
5240 /* Print the basic_block's header. */
5241 fprintf (file
, "%s bb_%d (preds = {", s_indent
, bb
->index
);
5242 print_pred_bbs (file
, bb
);
5243 fprintf (file
, "}, succs = {");
5244 print_succ_bbs (file
, bb
);
5245 fprintf (file
, "})\n");
5247 /* Print the basic_block's body. */
5248 fprintf (file
, "%s {\n", s_indent
);
5249 tree_dump_bb (bb
, file
, indent
+ 4);
5250 fprintf (file
, "%s }\n", s_indent
);
5253 print_loop (file
, loop
->inner
, indent
+ 2);
5254 fprintf (file
, "%s}\n", s_indent
);
5255 print_loop (file
, loop
->next
, indent
);
5259 /* Follow a CFG edge from the entry point of the program, and on entry
5260 of a loop, pretty print the loop structure on FILE. */
5263 print_loop_ir (FILE *file
)
5267 bb
= BASIC_BLOCK (0);
5268 if (bb
&& bb
->loop_father
)
5269 print_loop (file
, bb
->loop_father
, 0);
5273 /* Debugging loops structure at tree level. */
5276 debug_loop_ir (void)
5278 print_loop_ir (stderr
);
5282 /* Return true if BB ends with a call, possibly followed by some
5283 instructions that must stay with the call. Return false,
5287 tree_block_ends_with_call_p (basic_block bb
)
5289 block_stmt_iterator bsi
= bsi_last (bb
);
5290 return get_call_expr_in (bsi_stmt (bsi
)) != NULL
;
5294 /* Return true if BB ends with a conditional branch. Return false,
5298 tree_block_ends_with_condjump_p (basic_block bb
)
5300 tree stmt
= tsi_stmt (bsi_last (bb
).tsi
);
5301 return (TREE_CODE (stmt
) == COND_EXPR
);
5305 /* Return true if we need to add fake edge to exit at statement T.
5306 Helper function for tree_flow_call_edges_add. */
5309 need_fake_edge_p (tree t
)
5313 /* NORETURN and LONGJMP calls already have an edge to exit.
5314 CONST, PURE and ALWAYS_RETURN calls do not need one.
5315 We don't currently check for CONST and PURE here, although
5316 it would be a good idea, because those attributes are
5317 figured out from the RTL in mark_constant_function, and
5318 the counter incrementation code from -fprofile-arcs
5319 leads to different results from -fbranch-probabilities. */
5320 call
= get_call_expr_in (t
);
5322 && !(call_expr_flags (call
) & (ECF_NORETURN
| ECF_ALWAYS_RETURN
)))
5325 if (TREE_CODE (t
) == ASM_EXPR
5326 && (ASM_VOLATILE_P (t
) || ASM_INPUT_P (t
)))
5333 /* Add fake edges to the function exit for any non constant and non
5334 noreturn calls, volatile inline assembly in the bitmap of blocks
5335 specified by BLOCKS or to the whole CFG if BLOCKS is zero. Return
5336 the number of blocks that were split.
5338 The goal is to expose cases in which entering a basic block does
5339 not imply that all subsequent instructions must be executed. */
5342 tree_flow_call_edges_add (sbitmap blocks
)
5345 int blocks_split
= 0;
5346 int last_bb
= last_basic_block
;
5347 bool check_last_block
= false;
5349 if (n_basic_blocks
== 0)
5353 check_last_block
= true;
5355 check_last_block
= TEST_BIT (blocks
, EXIT_BLOCK_PTR
->prev_bb
->index
);
5357 /* In the last basic block, before epilogue generation, there will be
5358 a fallthru edge to EXIT. Special care is required if the last insn
5359 of the last basic block is a call because make_edge folds duplicate
5360 edges, which would result in the fallthru edge also being marked
5361 fake, which would result in the fallthru edge being removed by
5362 remove_fake_edges, which would result in an invalid CFG.
5364 Moreover, we can't elide the outgoing fake edge, since the block
5365 profiler needs to take this into account in order to solve the minimal
5366 spanning tree in the case that the call doesn't return.
5368 Handle this by adding a dummy instruction in a new last basic block. */
5369 if (check_last_block
)
5371 basic_block bb
= EXIT_BLOCK_PTR
->prev_bb
;
5372 block_stmt_iterator bsi
= bsi_last (bb
);
5374 if (!bsi_end_p (bsi
))
5377 if (need_fake_edge_p (t
))
5381 e
= find_edge (bb
, EXIT_BLOCK_PTR
);
5384 bsi_insert_on_edge (e
, build_empty_stmt ());
5385 bsi_commit_edge_inserts ();
5390 /* Now add fake edges to the function exit for any non constant
5391 calls since there is no way that we can determine if they will
5393 for (i
= 0; i
< last_bb
; i
++)
5395 basic_block bb
= BASIC_BLOCK (i
);
5396 block_stmt_iterator bsi
;
5397 tree stmt
, last_stmt
;
5402 if (blocks
&& !TEST_BIT (blocks
, i
))
5405 bsi
= bsi_last (bb
);
5406 if (!bsi_end_p (bsi
))
5408 last_stmt
= bsi_stmt (bsi
);
5411 stmt
= bsi_stmt (bsi
);
5412 if (need_fake_edge_p (stmt
))
5415 /* The handling above of the final block before the
5416 epilogue should be enough to verify that there is
5417 no edge to the exit block in CFG already.
5418 Calling make_edge in such case would cause us to
5419 mark that edge as fake and remove it later. */
5420 #ifdef ENABLE_CHECKING
5421 if (stmt
== last_stmt
)
5423 e
= find_edge (bb
, EXIT_BLOCK_PTR
);
5424 gcc_assert (e
== NULL
);
5428 /* Note that the following may create a new basic block
5429 and renumber the existing basic blocks. */
5430 if (stmt
!= last_stmt
)
5432 e
= split_block (bb
, stmt
);
5436 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
5440 while (!bsi_end_p (bsi
));
5445 verify_flow_info ();
5447 return blocks_split
;
5451 tree_purge_dead_eh_edges (basic_block bb
)
5453 bool changed
= false;
5456 tree stmt
= last_stmt (bb
);
5458 if (stmt
&& tree_can_throw_internal (stmt
))
5461 for (ei
= ei_start (bb
->succs
); (e
= ei_safe_edge (ei
)); )
5463 if (e
->flags
& EDGE_EH
)
5472 /* Removal of dead EH edges might change dominators of not
5473 just immediate successors. E.g. when bb1 is changed so that
5474 it no longer can throw and bb1->bb3 and bb1->bb4 are dead
5475 eh edges purged by this function in:
5487 idom(bb5) must be recomputed. For now just free the dominance
5490 free_dominance_info (CDI_DOMINATORS
);
5496 tree_purge_all_dead_eh_edges (bitmap blocks
)
5498 bool changed
= false;
5502 EXECUTE_IF_SET_IN_BITMAP (blocks
, 0, i
, bi
)
5504 changed
|= tree_purge_dead_eh_edges (BASIC_BLOCK (i
));
5510 /* This function is called whenever a new edge is created or
5514 tree_execute_on_growing_pred (edge e
)
5516 basic_block bb
= e
->dest
;
5519 reserve_phi_args_for_new_edge (bb
);
5522 /* This function is called immediately before edge E is removed from
5523 the edge vector E->dest->preds. */
5526 tree_execute_on_shrinking_pred (edge e
)
5528 if (phi_nodes (e
->dest
))
5529 remove_phi_args (e
);
5532 struct cfg_hooks tree_cfg_hooks
= {
5534 tree_verify_flow_info
,
5535 tree_dump_bb
, /* dump_bb */
5536 create_bb
, /* create_basic_block */
5537 tree_redirect_edge_and_branch
,/* redirect_edge_and_branch */
5538 tree_redirect_edge_and_branch_force
,/* redirect_edge_and_branch_force */
5539 remove_bb
, /* delete_basic_block */
5540 tree_split_block
, /* split_block */
5541 tree_move_block_after
, /* move_block_after */
5542 tree_can_merge_blocks_p
, /* can_merge_blocks_p */
5543 tree_merge_blocks
, /* merge_blocks */
5544 tree_predict_edge
, /* predict_edge */
5545 tree_predicted_by_p
, /* predicted_by_p */
5546 tree_can_duplicate_bb_p
, /* can_duplicate_block_p */
5547 tree_duplicate_bb
, /* duplicate_block */
5548 tree_split_edge
, /* split_edge */
5549 tree_make_forwarder_block
, /* make_forward_block */
5550 NULL
, /* tidy_fallthru_edge */
5551 tree_block_ends_with_call_p
, /* block_ends_with_call_p */
5552 tree_block_ends_with_condjump_p
, /* block_ends_with_condjump_p */
5553 tree_flow_call_edges_add
, /* flow_call_edges_add */
5554 tree_execute_on_growing_pred
, /* execute_on_growing_pred */
5555 tree_execute_on_shrinking_pred
, /* execute_on_shrinking_pred */
5559 /* Split all critical edges. */
5562 split_critical_edges (void)
5568 /* split_edge can redirect edges out of SWITCH_EXPRs, which can get
5569 expensive. So we want to enable recording of edge to CASE_LABEL_EXPR
5570 mappings around the calls to split_edge. */
5571 start_recording_case_labels ();
5574 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
5575 if (EDGE_CRITICAL_P (e
) && !(e
->flags
& EDGE_ABNORMAL
))
5580 end_recording_case_labels ();
5583 struct tree_opt_pass pass_split_crit_edges
=
5585 "crited", /* name */
5587 split_critical_edges
, /* execute */
5590 0, /* static_pass_number */
5591 TV_TREE_SPLIT_EDGES
, /* tv_id */
5592 PROP_cfg
, /* properties required */
5593 PROP_no_crit_edges
, /* properties_provided */
5594 0, /* properties_destroyed */
5595 0, /* todo_flags_start */
5596 TODO_dump_func
, /* todo_flags_finish */
5601 /* Return EXP if it is a valid GIMPLE rvalue, else gimplify it into
5602 a temporary, make sure and register it to be renamed if necessary,
5603 and finally return the temporary. Put the statements to compute
5604 EXP before the current statement in BSI. */
5607 gimplify_val (block_stmt_iterator
*bsi
, tree type
, tree exp
)
5609 tree t
, new_stmt
, orig_stmt
;
5611 if (is_gimple_val (exp
))
5614 t
= make_rename_temp (type
, NULL
);
5615 new_stmt
= build (MODIFY_EXPR
, type
, t
, exp
);
5617 orig_stmt
= bsi_stmt (*bsi
);
5618 SET_EXPR_LOCUS (new_stmt
, EXPR_LOCUS (orig_stmt
));
5619 TREE_BLOCK (new_stmt
) = TREE_BLOCK (orig_stmt
);
5621 bsi_insert_before (bsi
, new_stmt
, BSI_SAME_STMT
);
5626 /* Build a ternary operation and gimplify it. Emit code before BSI.
5627 Return the gimple_val holding the result. */
5630 gimplify_build3 (block_stmt_iterator
*bsi
, enum tree_code code
,
5631 tree type
, tree a
, tree b
, tree c
)
5635 ret
= fold (build3 (code
, type
, a
, b
, c
));
5638 return gimplify_val (bsi
, type
, ret
);
5641 /* Build a binary operation and gimplify it. Emit code before BSI.
5642 Return the gimple_val holding the result. */
5645 gimplify_build2 (block_stmt_iterator
*bsi
, enum tree_code code
,
5646 tree type
, tree a
, tree b
)
5650 ret
= fold (build2 (code
, type
, a
, b
));
5653 return gimplify_val (bsi
, type
, ret
);
5656 /* Build a unary operation and gimplify it. Emit code before BSI.
5657 Return the gimple_val holding the result. */
5660 gimplify_build1 (block_stmt_iterator
*bsi
, enum tree_code code
, tree type
,
5665 ret
= fold (build1 (code
, type
, a
));
5668 return gimplify_val (bsi
, type
, ret
);
5673 /* Emit return warnings. */
5676 execute_warn_function_return (void)
5678 #ifdef USE_MAPPED_LOCATION
5679 source_location location
;
5687 if (warn_missing_noreturn
5688 && !TREE_THIS_VOLATILE (cfun
->decl
)
5689 && EDGE_COUNT (EXIT_BLOCK_PTR
->preds
) == 0
5690 && !lang_hooks
.function
.missing_noreturn_ok_p (cfun
->decl
))
5691 warning ("%Jfunction might be possible candidate for "
5692 "attribute %<noreturn%>",
5695 /* If we have a path to EXIT, then we do return. */
5696 if (TREE_THIS_VOLATILE (cfun
->decl
)
5697 && EDGE_COUNT (EXIT_BLOCK_PTR
->preds
) > 0)
5699 #ifdef USE_MAPPED_LOCATION
5700 location
= UNKNOWN_LOCATION
;
5704 FOR_EACH_EDGE (e
, ei
, EXIT_BLOCK_PTR
->preds
)
5706 last
= last_stmt (e
->src
);
5707 if (TREE_CODE (last
) == RETURN_EXPR
5708 #ifdef USE_MAPPED_LOCATION
5709 && (location
= EXPR_LOCATION (last
)) != UNKNOWN_LOCATION
)
5711 && (locus
= EXPR_LOCUS (last
)) != NULL
)
5715 #ifdef USE_MAPPED_LOCATION
5716 if (location
== UNKNOWN_LOCATION
)
5717 location
= cfun
->function_end_locus
;
5718 warning ("%H%<noreturn%> function does return", &location
);
5721 locus
= &cfun
->function_end_locus
;
5722 warning ("%H%<noreturn%> function does return", locus
);
5726 /* If we see "return;" in some basic block, then we do reach the end
5727 without returning a value. */
5728 else if (warn_return_type
5729 && !TREE_NO_WARNING (cfun
->decl
)
5730 && EDGE_COUNT (EXIT_BLOCK_PTR
->preds
) > 0
5731 && !VOID_TYPE_P (TREE_TYPE (TREE_TYPE (cfun
->decl
))))
5733 FOR_EACH_EDGE (e
, ei
, EXIT_BLOCK_PTR
->preds
)
5735 tree last
= last_stmt (e
->src
);
5736 if (TREE_CODE (last
) == RETURN_EXPR
5737 && TREE_OPERAND (last
, 0) == NULL
)
5739 #ifdef USE_MAPPED_LOCATION
5740 location
= EXPR_LOCATION (last
);
5741 if (location
== UNKNOWN_LOCATION
)
5742 location
= cfun
->function_end_locus
;
5743 warning ("%Hcontrol reaches end of non-void function", &location
);
5745 locus
= EXPR_LOCUS (last
);
5747 locus
= &cfun
->function_end_locus
;
5748 warning ("%Hcontrol reaches end of non-void function", locus
);
5750 TREE_NO_WARNING (cfun
->decl
) = 1;
5758 /* Given a basic block B which ends with a conditional and has
5759 precisely two successors, determine which of the edges is taken if
5760 the conditional is true and which is taken if the conditional is
5761 false. Set TRUE_EDGE and FALSE_EDGE appropriately. */
5764 extract_true_false_edges_from_block (basic_block b
,
5768 edge e
= EDGE_SUCC (b
, 0);
5770 if (e
->flags
& EDGE_TRUE_VALUE
)
5773 *false_edge
= EDGE_SUCC (b
, 1);
5778 *true_edge
= EDGE_SUCC (b
, 1);
5782 struct tree_opt_pass pass_warn_function_return
=
5786 execute_warn_function_return
, /* execute */
5789 0, /* static_pass_number */
5791 PROP_cfg
, /* properties_required */
5792 0, /* properties_provided */
5793 0, /* properties_destroyed */
5794 0, /* todo_flags_start */
5795 0, /* todo_flags_finish */
5799 #include "gt-tree-cfg.h"