1 /* Control flow graph manipulation code for GNU compiler.
2 Copyright (C) 1987-2013 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify it under
7 the terms of the GNU General Public License as published by the Free
8 Software Foundation; either version 3, or (at your option) any later
11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING3. If not see
18 <http://www.gnu.org/licenses/>. */
20 /* This file contains low level functions to manipulate the CFG and analyze it
21 that are aware of the RTL intermediate language.
23 Available functionality:
24 - Basic CFG/RTL manipulation API documented in cfghooks.h
25 - CFG-aware instruction chain manipulation
26 delete_insn, delete_insn_chain
27 - Edge splitting and committing to edges
28 insert_insn_on_edge, commit_edge_insertions
29 - CFG updating after insn simplification
30 purge_dead_edges, purge_all_dead_edges
31 - CFG fixing after coarse manipulation
34 Functions not supposed for generic use:
35 - Infrastructure to determine quickly basic block for insn
36 compute_bb_for_insn, update_bb_for_insn, set_block_for_insn,
37 - Edge redirection with updating and optimizing of insn chain
38 block_label, tidy_fallthru_edge, force_nonfallthru */
42 #include "coretypes.h"
45 #include "hard-reg-set.h"
46 #include "basic-block.h"
51 #include "rtl-error.h"
54 #include "insn-attr.h"
55 #include "insn-config.h"
58 #include "common/common-target.h"
61 #include "tree-pass.h"
64 /* Holds the interesting leading and trailing notes for the function.
65 Only applicable if the CFG is in cfglayout mode. */
66 static GTY(()) rtx cfg_layout_function_footer
;
67 static GTY(()) rtx cfg_layout_function_header
;
69 static rtx
skip_insns_after_block (basic_block
);
70 static void record_effective_endpoints (void);
71 static rtx
label_for_bb (basic_block
);
72 static void fixup_reorder_chain (void);
74 void verify_insn_chain (void);
75 static void fixup_fallthru_exit_predecessor (void);
76 static int can_delete_note_p (const_rtx
);
77 static int can_delete_label_p (const_rtx
);
78 static basic_block
rtl_split_edge (edge
);
79 static bool rtl_move_block_after (basic_block
, basic_block
);
80 static int rtl_verify_flow_info (void);
81 static basic_block
cfg_layout_split_block (basic_block
, void *);
82 static edge
cfg_layout_redirect_edge_and_branch (edge
, basic_block
);
83 static basic_block
cfg_layout_redirect_edge_and_branch_force (edge
, basic_block
);
84 static void cfg_layout_delete_block (basic_block
);
85 static void rtl_delete_block (basic_block
);
86 static basic_block
rtl_redirect_edge_and_branch_force (edge
, basic_block
);
87 static edge
rtl_redirect_edge_and_branch (edge
, basic_block
);
88 static basic_block
rtl_split_block (basic_block
, void *);
89 static void rtl_dump_bb (FILE *, basic_block
, int, int);
90 static int rtl_verify_flow_info_1 (void);
91 static void rtl_make_forwarder_block (edge
);
93 /* Return true if NOTE is not one of the ones that must be kept paired,
94 so that we may simply delete it. */
97 can_delete_note_p (const_rtx note
)
99 switch (NOTE_KIND (note
))
101 case NOTE_INSN_DELETED
:
102 case NOTE_INSN_BASIC_BLOCK
:
103 case NOTE_INSN_EPILOGUE_BEG
:
111 /* True if a given label can be deleted. */
114 can_delete_label_p (const_rtx label
)
116 return (!LABEL_PRESERVE_P (label
)
117 /* User declared labels must be preserved. */
118 && LABEL_NAME (label
) == 0
119 && !in_expr_list_p (forced_labels
, label
));
122 /* Delete INSN by patching it out. */
125 delete_insn (rtx insn
)
128 bool really_delete
= true;
132 /* Some labels can't be directly removed from the INSN chain, as they
133 might be references via variables, constant pool etc.
134 Convert them to the special NOTE_INSN_DELETED_LABEL note. */
135 if (! can_delete_label_p (insn
))
137 const char *name
= LABEL_NAME (insn
);
138 basic_block bb
= BLOCK_FOR_INSN (insn
);
139 rtx bb_note
= NEXT_INSN (insn
);
141 really_delete
= false;
142 PUT_CODE (insn
, NOTE
);
143 NOTE_KIND (insn
) = NOTE_INSN_DELETED_LABEL
;
144 NOTE_DELETED_LABEL_NAME (insn
) = name
;
146 /* If the note following the label starts a basic block, and the
147 label is a member of the same basic block, interchange the two. */
148 if (bb_note
!= NULL_RTX
149 && NOTE_INSN_BASIC_BLOCK_P (bb_note
)
151 && bb
== BLOCK_FOR_INSN (bb_note
))
153 reorder_insns_nobb (insn
, insn
, bb_note
);
154 BB_HEAD (bb
) = bb_note
;
155 if (BB_END (bb
) == bb_note
)
160 remove_node_from_expr_list (insn
, &nonlocal_goto_handler_labels
);
165 /* If this insn has already been deleted, something is very wrong. */
166 gcc_assert (!INSN_DELETED_P (insn
));
168 df_insn_delete (insn
);
170 INSN_DELETED_P (insn
) = 1;
173 /* If deleting a jump, decrement the use count of the label. Deleting
174 the label itself should happen in the normal course of block merging. */
177 if (JUMP_LABEL (insn
)
178 && LABEL_P (JUMP_LABEL (insn
)))
179 LABEL_NUSES (JUMP_LABEL (insn
))--;
181 /* If there are more targets, remove them too. */
183 = find_reg_note (insn
, REG_LABEL_TARGET
, NULL_RTX
)) != NULL_RTX
184 && LABEL_P (XEXP (note
, 0)))
186 LABEL_NUSES (XEXP (note
, 0))--;
187 remove_note (insn
, note
);
191 /* Also if deleting any insn that references a label as an operand. */
192 while ((note
= find_reg_note (insn
, REG_LABEL_OPERAND
, NULL_RTX
)) != NULL_RTX
193 && LABEL_P (XEXP (note
, 0)))
195 LABEL_NUSES (XEXP (note
, 0))--;
196 remove_note (insn
, note
);
199 if (JUMP_TABLE_DATA_P (insn
))
201 rtx pat
= PATTERN (insn
);
202 int diff_vec_p
= GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
;
203 int len
= XVECLEN (pat
, diff_vec_p
);
206 for (i
= 0; i
< len
; i
++)
208 rtx label
= XEXP (XVECEXP (pat
, diff_vec_p
, i
), 0);
210 /* When deleting code in bulk (e.g. removing many unreachable
211 blocks) we can delete a label that's a target of the vector
212 before deleting the vector itself. */
214 LABEL_NUSES (label
)--;
219 /* Like delete_insn but also purge dead edges from BB. */
222 delete_insn_and_edges (rtx insn
)
227 && BLOCK_FOR_INSN (insn
)
228 && BB_END (BLOCK_FOR_INSN (insn
)) == insn
)
232 purge_dead_edges (BLOCK_FOR_INSN (insn
));
235 /* Unlink a chain of insns between START and FINISH, leaving notes
236 that must be paired. If CLEAR_BB is true, we set bb field for
237 insns that cannot be removed to NULL. */
240 delete_insn_chain (rtx start
, rtx finish
, bool clear_bb
)
244 /* Unchain the insns one by one. It would be quicker to delete all of these
245 with a single unchaining, rather than one at a time, but we need to keep
250 prev
= PREV_INSN (current
);
251 if (NOTE_P (current
) && !can_delete_note_p (current
))
254 delete_insn (current
);
256 if (clear_bb
&& !INSN_DELETED_P (current
))
257 set_block_for_insn (current
, NULL
);
259 if (current
== start
)
265 /* Create a new basic block consisting of the instructions between HEAD and END
266 inclusive. This function is designed to allow fast BB construction - reuses
267 the note and basic block struct in BB_NOTE, if any and do not grow
268 BASIC_BLOCK chain and should be used directly only by CFG construction code.
269 END can be NULL in to create new empty basic block before HEAD. Both END
270 and HEAD can be NULL to create basic block at the end of INSN chain.
271 AFTER is the basic block we should be put after. */
274 create_basic_block_structure (rtx head
, rtx end
, rtx bb_note
, basic_block after
)
279 && (bb
= NOTE_BASIC_BLOCK (bb_note
)) != NULL
282 /* If we found an existing note, thread it back onto the chain. */
290 after
= PREV_INSN (head
);
294 if (after
!= bb_note
&& NEXT_INSN (after
) != bb_note
)
295 reorder_insns_nobb (bb_note
, bb_note
, after
);
299 /* Otherwise we must create a note and a basic block structure. */
303 init_rtl_bb_info (bb
);
306 = emit_note_after (NOTE_INSN_BASIC_BLOCK
, get_last_insn ());
307 else if (LABEL_P (head
) && end
)
309 bb_note
= emit_note_after (NOTE_INSN_BASIC_BLOCK
, head
);
315 bb_note
= emit_note_before (NOTE_INSN_BASIC_BLOCK
, head
);
321 NOTE_BASIC_BLOCK (bb_note
) = bb
;
324 /* Always include the bb note in the block. */
325 if (NEXT_INSN (end
) == bb_note
)
330 bb
->index
= last_basic_block
++;
331 bb
->flags
= BB_NEW
| BB_RTL
;
332 link_block (bb
, after
);
333 SET_BASIC_BLOCK (bb
->index
, bb
);
334 df_bb_refs_record (bb
->index
, false);
335 update_bb_for_insn (bb
);
336 BB_SET_PARTITION (bb
, BB_UNPARTITIONED
);
338 /* Tag the block so that we know it has been used when considering
339 other basic block notes. */
345 /* Create new basic block consisting of instructions in between HEAD and END
346 and place it to the BB chain after block AFTER. END can be NULL to
347 create a new empty basic block before HEAD. Both END and HEAD can be
348 NULL to create basic block at the end of INSN chain. */
351 rtl_create_basic_block (void *headp
, void *endp
, basic_block after
)
353 rtx head
= (rtx
) headp
, end
= (rtx
) endp
;
356 /* Grow the basic block array if needed. */
357 if ((size_t) last_basic_block
>= basic_block_info
->length ())
359 size_t new_size
= last_basic_block
+ (last_basic_block
+ 3) / 4;
360 vec_safe_grow_cleared (basic_block_info
, new_size
);
365 bb
= create_basic_block_structure (head
, end
, NULL
, after
);
371 cfg_layout_create_basic_block (void *head
, void *end
, basic_block after
)
373 basic_block newbb
= rtl_create_basic_block (head
, end
, after
);
378 /* Delete the insns in a (non-live) block. We physically delete every
379 non-deleted-note insn, and update the flow graph appropriately.
381 Return nonzero if we deleted an exception handler. */
383 /* ??? Preserving all such notes strikes me as wrong. It would be nice
384 to post-process the stream to remove empty blocks, loops, ranges, etc. */
387 rtl_delete_block (basic_block b
)
391 /* If the head of this block is a CODE_LABEL, then it might be the
392 label for an exception handler which can't be reached. We need
393 to remove the label from the exception_handler_label list. */
396 end
= get_last_bb_insn (b
);
398 /* Selectively delete the entire chain. */
400 delete_insn_chain (insn
, end
, true);
404 fprintf (dump_file
, "deleting block %d\n", b
->index
);
405 df_bb_delete (b
->index
);
408 /* Records the basic block struct in BLOCK_FOR_INSN for every insn. */
411 compute_bb_for_insn (void)
417 rtx end
= BB_END (bb
);
420 for (insn
= BB_HEAD (bb
); ; insn
= NEXT_INSN (insn
))
422 BLOCK_FOR_INSN (insn
) = bb
;
429 /* Release the basic_block_for_insn array. */
432 free_bb_for_insn (void)
435 for (insn
= get_insns (); insn
; insn
= NEXT_INSN (insn
))
436 if (!BARRIER_P (insn
))
437 BLOCK_FOR_INSN (insn
) = NULL
;
442 rest_of_pass_free_cfg (void)
445 /* The resource.c machinery uses DF but the CFG isn't guaranteed to be
446 valid at that point so it would be too late to call df_analyze. */
447 if (optimize
> 0 && flag_delayed_branch
)
449 df_note_add_problem ();
458 struct rtl_opt_pass pass_free_cfg
=
462 "*free_cfg", /* name */
463 OPTGROUP_NONE
, /* optinfo_flags */
465 rest_of_pass_free_cfg
, /* execute */
468 0, /* static_pass_number */
470 0, /* properties_required */
471 0, /* properties_provided */
472 PROP_cfg
, /* properties_destroyed */
473 0, /* todo_flags_start */
474 0, /* todo_flags_finish */
478 /* Return RTX to emit after when we want to emit code on the entry of function. */
480 entry_of_function (void)
482 return (n_basic_blocks
> NUM_FIXED_BLOCKS
?
483 BB_HEAD (ENTRY_BLOCK_PTR
->next_bb
) : get_insns ());
486 /* Emit INSN at the entry point of the function, ensuring that it is only
487 executed once per function. */
489 emit_insn_at_entry (rtx insn
)
491 edge_iterator ei
= ei_start (ENTRY_BLOCK_PTR
->succs
);
492 edge e
= ei_safe_edge (ei
);
493 gcc_assert (e
->flags
& EDGE_FALLTHRU
);
495 insert_insn_on_edge (insn
, e
);
496 commit_edge_insertions ();
499 /* Update BLOCK_FOR_INSN of insns between BEGIN and END
500 (or BARRIER if found) and notify df of the bb change.
501 The insn chain range is inclusive
502 (i.e. both BEGIN and END will be updated. */
505 update_bb_for_insn_chain (rtx begin
, rtx end
, basic_block bb
)
509 end
= NEXT_INSN (end
);
510 for (insn
= begin
; insn
!= end
; insn
= NEXT_INSN (insn
))
511 if (!BARRIER_P (insn
))
512 df_insn_change_bb (insn
, bb
);
515 /* Update BLOCK_FOR_INSN of insns in BB to BB,
516 and notify df of the change. */
519 update_bb_for_insn (basic_block bb
)
521 update_bb_for_insn_chain (BB_HEAD (bb
), BB_END (bb
), bb
);
525 /* Like active_insn_p, except keep the return value clobber around
526 even after reload. */
529 flow_active_insn_p (const_rtx insn
)
531 if (active_insn_p (insn
))
534 /* A clobber of the function return value exists for buggy
535 programs that fail to return a value. Its effect is to
536 keep the return value from being live across the entire
537 function. If we allow it to be skipped, we introduce the
538 possibility for register lifetime confusion. */
539 if (GET_CODE (PATTERN (insn
)) == CLOBBER
540 && REG_P (XEXP (PATTERN (insn
), 0))
541 && REG_FUNCTION_VALUE_P (XEXP (PATTERN (insn
), 0)))
547 /* Return true if the block has no effect and only forwards control flow to
548 its single destination. */
551 contains_no_active_insn_p (const_basic_block bb
)
555 if (bb
== EXIT_BLOCK_PTR
|| bb
== ENTRY_BLOCK_PTR
556 || !single_succ_p (bb
))
559 for (insn
= BB_HEAD (bb
); insn
!= BB_END (bb
); insn
= NEXT_INSN (insn
))
560 if (INSN_P (insn
) && flow_active_insn_p (insn
))
563 return (!INSN_P (insn
)
564 || (JUMP_P (insn
) && simplejump_p (insn
))
565 || !flow_active_insn_p (insn
));
568 /* Likewise, but protect loop latches, headers and preheaders. */
569 /* FIXME: Make this a cfg hook. */
572 forwarder_block_p (const_basic_block bb
)
574 if (!contains_no_active_insn_p (bb
))
577 /* Protect loop latches, headers and preheaders. */
581 if (bb
->loop_father
->header
== bb
)
583 dest
= EDGE_SUCC (bb
, 0)->dest
;
584 if (dest
->loop_father
->header
== dest
)
591 /* Return nonzero if we can reach target from src by falling through. */
592 /* FIXME: Make this a cfg hook. */
595 can_fallthru (basic_block src
, basic_block target
)
597 rtx insn
= BB_END (src
);
602 if (target
== EXIT_BLOCK_PTR
)
604 if (src
->next_bb
!= target
)
606 FOR_EACH_EDGE (e
, ei
, src
->succs
)
607 if (e
->dest
== EXIT_BLOCK_PTR
608 && e
->flags
& EDGE_FALLTHRU
)
611 insn2
= BB_HEAD (target
);
612 if (insn2
&& !active_insn_p (insn2
))
613 insn2
= next_active_insn (insn2
);
615 /* ??? Later we may add code to move jump tables offline. */
616 return next_active_insn (insn
) == insn2
;
619 /* Return nonzero if we could reach target from src by falling through,
620 if the target was made adjacent. If we already have a fall-through
621 edge to the exit block, we can't do that. */
623 could_fall_through (basic_block src
, basic_block target
)
628 if (target
== EXIT_BLOCK_PTR
)
630 FOR_EACH_EDGE (e
, ei
, src
->succs
)
631 if (e
->dest
== EXIT_BLOCK_PTR
632 && e
->flags
& EDGE_FALLTHRU
)
637 /* Return the NOTE_INSN_BASIC_BLOCK of BB. */
639 bb_note (basic_block bb
)
645 note
= NEXT_INSN (note
);
647 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (note
));
651 /* Return the INSN immediately following the NOTE_INSN_BASIC_BLOCK
652 note associated with the BLOCK. */
655 first_insn_after_basic_block_note (basic_block block
)
659 /* Get the first instruction in the block. */
660 insn
= BB_HEAD (block
);
662 if (insn
== NULL_RTX
)
665 insn
= NEXT_INSN (insn
);
666 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (insn
));
668 return NEXT_INSN (insn
);
671 /* Creates a new basic block just after basic block B by splitting
672 everything after specified instruction I. */
675 rtl_split_block (basic_block bb
, void *insnp
)
678 rtx insn
= (rtx
) insnp
;
684 insn
= first_insn_after_basic_block_note (bb
);
690 insn
= PREV_INSN (insn
);
692 /* If the block contains only debug insns, insn would have
693 been NULL in a non-debug compilation, and then we'd end
694 up emitting a DELETED note. For -fcompare-debug
695 stability, emit the note too. */
696 if (insn
!= BB_END (bb
)
697 && DEBUG_INSN_P (next
)
698 && DEBUG_INSN_P (BB_END (bb
)))
700 while (next
!= BB_END (bb
) && DEBUG_INSN_P (next
))
701 next
= NEXT_INSN (next
);
703 if (next
== BB_END (bb
))
704 emit_note_after (NOTE_INSN_DELETED
, next
);
708 insn
= get_last_insn ();
711 /* We probably should check type of the insn so that we do not create
712 inconsistent cfg. It is checked in verify_flow_info anyway, so do not
714 if (insn
== BB_END (bb
))
715 emit_note_after (NOTE_INSN_DELETED
, insn
);
717 /* Create the new basic block. */
718 new_bb
= create_basic_block (NEXT_INSN (insn
), BB_END (bb
), bb
);
719 BB_COPY_PARTITION (new_bb
, bb
);
722 /* Redirect the outgoing edges. */
723 new_bb
->succs
= bb
->succs
;
725 FOR_EACH_EDGE (e
, ei
, new_bb
->succs
)
728 /* The new block starts off being dirty. */
729 df_set_bb_dirty (bb
);
733 /* Return true if the single edge between blocks A and B is the only place
734 in RTL which holds some unique locus. */
737 unique_locus_on_edge_between_p (basic_block a
, basic_block b
)
739 const location_t goto_locus
= EDGE_SUCC (a
, 0)->goto_locus
;
742 if (LOCATION_LOCUS (goto_locus
) == UNKNOWN_LOCATION
)
745 /* First scan block A backward. */
747 end
= PREV_INSN (BB_HEAD (a
));
748 while (insn
!= end
&& (!NONDEBUG_INSN_P (insn
) || !INSN_HAS_LOCATION (insn
)))
749 insn
= PREV_INSN (insn
);
751 if (insn
!= end
&& INSN_LOCATION (insn
) == goto_locus
)
754 /* Then scan block B forward. */
758 end
= NEXT_INSN (BB_END (b
));
759 while (insn
!= end
&& !NONDEBUG_INSN_P (insn
))
760 insn
= NEXT_INSN (insn
);
762 if (insn
!= end
&& INSN_HAS_LOCATION (insn
)
763 && INSN_LOCATION (insn
) == goto_locus
)
770 /* If the single edge between blocks A and B is the only place in RTL which
771 holds some unique locus, emit a nop with that locus between the blocks. */
774 emit_nop_for_unique_locus_between (basic_block a
, basic_block b
)
776 if (!unique_locus_on_edge_between_p (a
, b
))
779 BB_END (a
) = emit_insn_after_noloc (gen_nop (), BB_END (a
), a
);
780 INSN_LOCATION (BB_END (a
)) = EDGE_SUCC (a
, 0)->goto_locus
;
783 /* Blocks A and B are to be merged into a single block A. The insns
784 are already contiguous. */
787 rtl_merge_blocks (basic_block a
, basic_block b
)
789 rtx b_head
= BB_HEAD (b
), b_end
= BB_END (b
), a_end
= BB_END (a
);
790 rtx del_first
= NULL_RTX
, del_last
= NULL_RTX
;
791 rtx b_debug_start
= b_end
, b_debug_end
= b_end
;
792 bool forwarder_p
= (b
->flags
& BB_FORWARDER_BLOCK
) != 0;
796 fprintf (dump_file
, "Merging block %d into block %d...\n", b
->index
,
799 while (DEBUG_INSN_P (b_end
))
800 b_end
= PREV_INSN (b_debug_start
= b_end
);
802 /* If there was a CODE_LABEL beginning B, delete it. */
803 if (LABEL_P (b_head
))
805 /* Detect basic blocks with nothing but a label. This can happen
806 in particular at the end of a function. */
810 del_first
= del_last
= b_head
;
811 b_head
= NEXT_INSN (b_head
);
814 /* Delete the basic block note and handle blocks containing just that
816 if (NOTE_INSN_BASIC_BLOCK_P (b_head
))
824 b_head
= NEXT_INSN (b_head
);
827 /* If there was a jump out of A, delete it. */
832 for (prev
= PREV_INSN (a_end
); ; prev
= PREV_INSN (prev
))
834 || NOTE_INSN_BASIC_BLOCK_P (prev
)
835 || prev
== BB_HEAD (a
))
841 /* If this was a conditional jump, we need to also delete
842 the insn that set cc0. */
843 if (only_sets_cc0_p (prev
))
847 prev
= prev_nonnote_insn (prev
);
854 a_end
= PREV_INSN (del_first
);
856 else if (BARRIER_P (NEXT_INSN (a_end
)))
857 del_first
= NEXT_INSN (a_end
);
859 /* Delete everything marked above as well as crap that might be
860 hanging out between the two blocks. */
862 BB_HEAD (b
) = b_empty
? NULL_RTX
: b_head
;
863 delete_insn_chain (del_first
, del_last
, true);
865 /* When not optimizing CFG and the edge is the only place in RTL which holds
866 some unique locus, emit a nop with that locus in between. */
869 emit_nop_for_unique_locus_between (a
, b
);
873 /* Reassociate the insns of B with A. */
876 update_bb_for_insn_chain (a_end
, b_debug_end
, a
);
878 BB_END (a
) = b_debug_end
;
879 BB_HEAD (b
) = NULL_RTX
;
881 else if (b_end
!= b_debug_end
)
883 /* Move any deleted labels and other notes between the end of A
884 and the debug insns that make up B after the debug insns,
885 bringing the debug insns into A while keeping the notes after
887 if (NEXT_INSN (a_end
) != b_debug_start
)
888 reorder_insns_nobb (NEXT_INSN (a_end
), PREV_INSN (b_debug_start
),
890 update_bb_for_insn_chain (b_debug_start
, b_debug_end
, a
);
891 BB_END (a
) = b_debug_end
;
894 df_bb_delete (b
->index
);
896 /* If B was a forwarder block, propagate the locus on the edge. */
898 && LOCATION_LOCUS (EDGE_SUCC (b
, 0)->goto_locus
) == UNKNOWN_LOCATION
)
899 EDGE_SUCC (b
, 0)->goto_locus
= EDGE_SUCC (a
, 0)->goto_locus
;
902 fprintf (dump_file
, "Merged blocks %d and %d.\n", a
->index
, b
->index
);
906 /* Return true when block A and B can be merged. */
909 rtl_can_merge_blocks (basic_block a
, basic_block b
)
911 /* If we are partitioning hot/cold basic blocks, we don't want to
912 mess up unconditional or indirect jumps that cross between hot
915 Basic block partitioning may result in some jumps that appear to
916 be optimizable (or blocks that appear to be mergeable), but which really
917 must be left untouched (they are required to make it safely across
918 partition boundaries). See the comments at the top of
919 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
921 if (BB_PARTITION (a
) != BB_PARTITION (b
))
924 /* Protect the loop latches. */
925 if (current_loops
&& b
->loop_father
->latch
== b
)
928 /* There must be exactly one edge in between the blocks. */
929 return (single_succ_p (a
)
930 && single_succ (a
) == b
933 /* Must be simple edge. */
934 && !(single_succ_edge (a
)->flags
& EDGE_COMPLEX
)
936 && a
!= ENTRY_BLOCK_PTR
&& b
!= EXIT_BLOCK_PTR
937 /* If the jump insn has side effects,
938 we can't kill the edge. */
939 && (!JUMP_P (BB_END (a
))
941 ? simplejump_p (BB_END (a
)) : onlyjump_p (BB_END (a
)))));
944 /* Return the label in the head of basic block BLOCK. Create one if it doesn't
948 block_label (basic_block block
)
950 if (block
== EXIT_BLOCK_PTR
)
953 if (!LABEL_P (BB_HEAD (block
)))
955 BB_HEAD (block
) = emit_label_before (gen_label_rtx (), BB_HEAD (block
));
958 return BB_HEAD (block
);
961 /* Attempt to perform edge redirection by replacing possibly complex jump
962 instruction by unconditional jump or removing jump completely. This can
963 apply only if all edges now point to the same block. The parameters and
964 return values are equivalent to redirect_edge_and_branch. */
967 try_redirect_by_replacing_jump (edge e
, basic_block target
, bool in_cfglayout
)
969 basic_block src
= e
->src
;
970 rtx insn
= BB_END (src
), kill_from
;
974 /* If we are partitioning hot/cold basic blocks, we don't want to
975 mess up unconditional or indirect jumps that cross between hot
978 Basic block partitioning may result in some jumps that appear to
979 be optimizable (or blocks that appear to be mergeable), but which really
980 must be left untouched (they are required to make it safely across
981 partition boundaries). See the comments at the top of
982 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
984 if (find_reg_note (insn
, REG_CROSSING_JUMP
, NULL_RTX
)
985 || BB_PARTITION (src
) != BB_PARTITION (target
))
988 /* We can replace or remove a complex jump only when we have exactly
989 two edges. Also, if we have exactly one outgoing edge, we can
991 if (EDGE_COUNT (src
->succs
) >= 3
992 /* Verify that all targets will be TARGET. Specifically, the
993 edge that is not E must also go to TARGET. */
994 || (EDGE_COUNT (src
->succs
) == 2
995 && EDGE_SUCC (src
, EDGE_SUCC (src
, 0) == e
)->dest
!= target
))
998 if (!onlyjump_p (insn
))
1000 if ((!optimize
|| reload_completed
) && tablejump_p (insn
, NULL
, NULL
))
1003 /* Avoid removing branch with side effects. */
1004 set
= single_set (insn
);
1005 if (!set
|| side_effects_p (set
))
1008 /* In case we zap a conditional jump, we'll need to kill
1009 the cc0 setter too. */
1012 if (reg_mentioned_p (cc0_rtx
, PATTERN (insn
))
1013 && only_sets_cc0_p (PREV_INSN (insn
)))
1014 kill_from
= PREV_INSN (insn
);
1017 /* See if we can create the fallthru edge. */
1018 if (in_cfglayout
|| can_fallthru (src
, target
))
1021 fprintf (dump_file
, "Removing jump %i.\n", INSN_UID (insn
));
1024 /* Selectively unlink whole insn chain. */
1027 rtx insn
= BB_FOOTER (src
);
1029 delete_insn_chain (kill_from
, BB_END (src
), false);
1031 /* Remove barriers but keep jumptables. */
1034 if (BARRIER_P (insn
))
1036 if (PREV_INSN (insn
))
1037 NEXT_INSN (PREV_INSN (insn
)) = NEXT_INSN (insn
);
1039 BB_FOOTER (src
) = NEXT_INSN (insn
);
1040 if (NEXT_INSN (insn
))
1041 PREV_INSN (NEXT_INSN (insn
)) = PREV_INSN (insn
);
1045 insn
= NEXT_INSN (insn
);
1049 delete_insn_chain (kill_from
, PREV_INSN (BB_HEAD (target
)),
1053 /* If this already is simplejump, redirect it. */
1054 else if (simplejump_p (insn
))
1056 if (e
->dest
== target
)
1059 fprintf (dump_file
, "Redirecting jump %i from %i to %i.\n",
1060 INSN_UID (insn
), e
->dest
->index
, target
->index
);
1061 if (!redirect_jump (insn
, block_label (target
), 0))
1063 gcc_assert (target
== EXIT_BLOCK_PTR
);
1068 /* Cannot do anything for target exit block. */
1069 else if (target
== EXIT_BLOCK_PTR
)
1072 /* Or replace possibly complicated jump insn by simple jump insn. */
1075 rtx target_label
= block_label (target
);
1076 rtx barrier
, label
, table
;
1078 emit_jump_insn_after_noloc (gen_jump (target_label
), insn
);
1079 JUMP_LABEL (BB_END (src
)) = target_label
;
1080 LABEL_NUSES (target_label
)++;
1082 fprintf (dump_file
, "Replacing insn %i by jump %i\n",
1083 INSN_UID (insn
), INSN_UID (BB_END (src
)));
1086 delete_insn_chain (kill_from
, insn
, false);
1088 /* Recognize a tablejump that we are converting to a
1089 simple jump and remove its associated CODE_LABEL
1090 and ADDR_VEC or ADDR_DIFF_VEC. */
1091 if (tablejump_p (insn
, &label
, &table
))
1092 delete_insn_chain (label
, table
, false);
1094 barrier
= next_nonnote_insn (BB_END (src
));
1095 if (!barrier
|| !BARRIER_P (barrier
))
1096 emit_barrier_after (BB_END (src
));
1099 if (barrier
!= NEXT_INSN (BB_END (src
)))
1101 /* Move the jump before barrier so that the notes
1102 which originally were or were created before jump table are
1103 inside the basic block. */
1104 rtx new_insn
= BB_END (src
);
1106 update_bb_for_insn_chain (NEXT_INSN (BB_END (src
)),
1107 PREV_INSN (barrier
), src
);
1109 NEXT_INSN (PREV_INSN (new_insn
)) = NEXT_INSN (new_insn
);
1110 PREV_INSN (NEXT_INSN (new_insn
)) = PREV_INSN (new_insn
);
1112 NEXT_INSN (new_insn
) = barrier
;
1113 NEXT_INSN (PREV_INSN (barrier
)) = new_insn
;
1115 PREV_INSN (new_insn
) = PREV_INSN (barrier
);
1116 PREV_INSN (barrier
) = new_insn
;
1121 /* Keep only one edge out and set proper flags. */
1122 if (!single_succ_p (src
))
1124 gcc_assert (single_succ_p (src
));
1126 e
= single_succ_edge (src
);
1128 e
->flags
= EDGE_FALLTHRU
;
1132 e
->probability
= REG_BR_PROB_BASE
;
1133 e
->count
= src
->count
;
1135 if (e
->dest
!= target
)
1136 redirect_edge_succ (e
, target
);
1140 /* Subroutine of redirect_branch_edge that tries to patch the jump
1141 instruction INSN so that it reaches block NEW. Do this
1142 only when it originally reached block OLD. Return true if this
1143 worked or the original target wasn't OLD, return false if redirection
1147 patch_jump_insn (rtx insn
, rtx old_label
, basic_block new_bb
)
1150 /* Recognize a tablejump and adjust all matching cases. */
1151 if (tablejump_p (insn
, NULL
, &tmp
))
1155 rtx new_label
= block_label (new_bb
);
1157 if (new_bb
== EXIT_BLOCK_PTR
)
1159 if (GET_CODE (PATTERN (tmp
)) == ADDR_VEC
)
1160 vec
= XVEC (PATTERN (tmp
), 0);
1162 vec
= XVEC (PATTERN (tmp
), 1);
1164 for (j
= GET_NUM_ELEM (vec
) - 1; j
>= 0; --j
)
1165 if (XEXP (RTVEC_ELT (vec
, j
), 0) == old_label
)
1167 RTVEC_ELT (vec
, j
) = gen_rtx_LABEL_REF (Pmode
, new_label
);
1168 --LABEL_NUSES (old_label
);
1169 ++LABEL_NUSES (new_label
);
1172 /* Handle casesi dispatch insns. */
1173 if ((tmp
= single_set (insn
)) != NULL
1174 && SET_DEST (tmp
) == pc_rtx
1175 && GET_CODE (SET_SRC (tmp
)) == IF_THEN_ELSE
1176 && GET_CODE (XEXP (SET_SRC (tmp
), 2)) == LABEL_REF
1177 && XEXP (XEXP (SET_SRC (tmp
), 2), 0) == old_label
)
1179 XEXP (SET_SRC (tmp
), 2) = gen_rtx_LABEL_REF (Pmode
,
1181 --LABEL_NUSES (old_label
);
1182 ++LABEL_NUSES (new_label
);
1185 else if ((tmp
= extract_asm_operands (PATTERN (insn
))) != NULL
)
1187 int i
, n
= ASM_OPERANDS_LABEL_LENGTH (tmp
);
1188 rtx new_label
, note
;
1190 if (new_bb
== EXIT_BLOCK_PTR
)
1192 new_label
= block_label (new_bb
);
1194 for (i
= 0; i
< n
; ++i
)
1196 rtx old_ref
= ASM_OPERANDS_LABEL (tmp
, i
);
1197 gcc_assert (GET_CODE (old_ref
) == LABEL_REF
);
1198 if (XEXP (old_ref
, 0) == old_label
)
1200 ASM_OPERANDS_LABEL (tmp
, i
)
1201 = gen_rtx_LABEL_REF (Pmode
, new_label
);
1202 --LABEL_NUSES (old_label
);
1203 ++LABEL_NUSES (new_label
);
1207 if (JUMP_LABEL (insn
) == old_label
)
1209 JUMP_LABEL (insn
) = new_label
;
1210 note
= find_reg_note (insn
, REG_LABEL_TARGET
, new_label
);
1212 remove_note (insn
, note
);
1216 note
= find_reg_note (insn
, REG_LABEL_TARGET
, old_label
);
1218 remove_note (insn
, note
);
1219 if (JUMP_LABEL (insn
) != new_label
1220 && !find_reg_note (insn
, REG_LABEL_TARGET
, new_label
))
1221 add_reg_note (insn
, REG_LABEL_TARGET
, new_label
);
1223 while ((note
= find_reg_note (insn
, REG_LABEL_OPERAND
, old_label
))
1225 XEXP (note
, 0) = new_label
;
1229 /* ?? We may play the games with moving the named labels from
1230 one basic block to the other in case only one computed_jump is
1232 if (computed_jump_p (insn
)
1233 /* A return instruction can't be redirected. */
1234 || returnjump_p (insn
))
1237 if (!currently_expanding_to_rtl
|| JUMP_LABEL (insn
) == old_label
)
1239 /* If the insn doesn't go where we think, we're confused. */
1240 gcc_assert (JUMP_LABEL (insn
) == old_label
);
1242 /* If the substitution doesn't succeed, die. This can happen
1243 if the back end emitted unrecognizable instructions or if
1244 target is exit block on some arches. */
1245 if (!redirect_jump (insn
, block_label (new_bb
), 0))
1247 gcc_assert (new_bb
== EXIT_BLOCK_PTR
);
1256 /* Redirect edge representing branch of (un)conditional jump or tablejump,
1259 redirect_branch_edge (edge e
, basic_block target
)
1261 rtx old_label
= BB_HEAD (e
->dest
);
1262 basic_block src
= e
->src
;
1263 rtx insn
= BB_END (src
);
1265 /* We can only redirect non-fallthru edges of jump insn. */
1266 if (e
->flags
& EDGE_FALLTHRU
)
1268 else if (!JUMP_P (insn
) && !currently_expanding_to_rtl
)
1271 if (!currently_expanding_to_rtl
)
1273 if (!patch_jump_insn (insn
, old_label
, target
))
1277 /* When expanding this BB might actually contain multiple
1278 jumps (i.e. not yet split by find_many_sub_basic_blocks).
1279 Redirect all of those that match our label. */
1280 FOR_BB_INSNS (src
, insn
)
1281 if (JUMP_P (insn
) && !patch_jump_insn (insn
, old_label
, target
))
1285 fprintf (dump_file
, "Edge %i->%i redirected to %i\n",
1286 e
->src
->index
, e
->dest
->index
, target
->index
);
1288 if (e
->dest
!= target
)
1289 e
= redirect_edge_succ_nodup (e
, target
);
1294 /* Attempt to change code to redirect edge E to TARGET. Don't do that on
1295 expense of adding new instructions or reordering basic blocks.
1297 Function can be also called with edge destination equivalent to the TARGET.
1298 Then it should try the simplifications and do nothing if none is possible.
1300 Return edge representing the branch if transformation succeeded. Return NULL
1302 We still return NULL in case E already destinated TARGET and we didn't
1303 managed to simplify instruction stream. */
1306 rtl_redirect_edge_and_branch (edge e
, basic_block target
)
1309 basic_block src
= e
->src
;
1311 if (e
->flags
& (EDGE_ABNORMAL_CALL
| EDGE_EH
))
1314 if (e
->dest
== target
)
1317 if ((ret
= try_redirect_by_replacing_jump (e
, target
, false)) != NULL
)
1319 df_set_bb_dirty (src
);
1323 ret
= redirect_branch_edge (e
, target
);
1327 df_set_bb_dirty (src
);
1331 /* Like force_nonfallthru below, but additionally performs redirection
1332 Used by redirect_edge_and_branch_force. JUMP_LABEL is used only
1333 when redirecting to the EXIT_BLOCK, it is either ret_rtx or
1334 simple_return_rtx, indicating which kind of returnjump to create.
1335 It should be NULL otherwise. */
1338 force_nonfallthru_and_redirect (edge e
, basic_block target
, rtx jump_label
)
1340 basic_block jump_block
, new_bb
= NULL
, src
= e
->src
;
1343 int abnormal_edge_flags
= 0;
1344 bool asm_goto_edge
= false;
1347 /* In the case the last instruction is conditional jump to the next
1348 instruction, first redirect the jump itself and then continue
1349 by creating a basic block afterwards to redirect fallthru edge. */
1350 if (e
->src
!= ENTRY_BLOCK_PTR
&& e
->dest
!= EXIT_BLOCK_PTR
1351 && any_condjump_p (BB_END (e
->src
))
1352 && JUMP_LABEL (BB_END (e
->src
)) == BB_HEAD (e
->dest
))
1355 edge b
= unchecked_make_edge (e
->src
, target
, 0);
1358 redirected
= redirect_jump (BB_END (e
->src
), block_label (target
), 0);
1359 gcc_assert (redirected
);
1361 note
= find_reg_note (BB_END (e
->src
), REG_BR_PROB
, NULL_RTX
);
1364 int prob
= INTVAL (XEXP (note
, 0));
1366 b
->probability
= prob
;
1367 /* Update this to use GCOV_COMPUTE_SCALE. */
1368 b
->count
= e
->count
* prob
/ REG_BR_PROB_BASE
;
1369 e
->probability
-= e
->probability
;
1370 e
->count
-= b
->count
;
1371 if (e
->probability
< 0)
1378 if (e
->flags
& EDGE_ABNORMAL
)
1380 /* Irritating special case - fallthru edge to the same block as abnormal
1382 We can't redirect abnormal edge, but we still can split the fallthru
1383 one and create separate abnormal edge to original destination.
1384 This allows bb-reorder to make such edge non-fallthru. */
1385 gcc_assert (e
->dest
== target
);
1386 abnormal_edge_flags
= e
->flags
& ~EDGE_FALLTHRU
;
1387 e
->flags
&= EDGE_FALLTHRU
;
1391 gcc_assert (e
->flags
& EDGE_FALLTHRU
);
1392 if (e
->src
== ENTRY_BLOCK_PTR
)
1394 /* We can't redirect the entry block. Create an empty block
1395 at the start of the function which we use to add the new
1401 basic_block bb
= create_basic_block (BB_HEAD (e
->dest
), NULL
, ENTRY_BLOCK_PTR
);
1403 /* Change the existing edge's source to be the new block, and add
1404 a new edge from the entry block to the new block. */
1406 for (ei
= ei_start (ENTRY_BLOCK_PTR
->succs
); (tmp
= ei_safe_edge (ei
)); )
1410 ENTRY_BLOCK_PTR
->succs
->unordered_remove (ei
.index
);
1420 vec_safe_push (bb
->succs
, e
);
1421 make_single_succ_edge (ENTRY_BLOCK_PTR
, bb
, EDGE_FALLTHRU
);
1425 /* If e->src ends with asm goto, see if any of the ASM_OPERANDS_LABELs
1426 don't point to the target or fallthru label. */
1427 if (JUMP_P (BB_END (e
->src
))
1428 && target
!= EXIT_BLOCK_PTR
1429 && (e
->flags
& EDGE_FALLTHRU
)
1430 && (note
= extract_asm_operands (PATTERN (BB_END (e
->src
)))))
1432 int i
, n
= ASM_OPERANDS_LABEL_LENGTH (note
);
1433 bool adjust_jump_target
= false;
1435 for (i
= 0; i
< n
; ++i
)
1437 if (XEXP (ASM_OPERANDS_LABEL (note
, i
), 0) == BB_HEAD (e
->dest
))
1439 LABEL_NUSES (XEXP (ASM_OPERANDS_LABEL (note
, i
), 0))--;
1440 XEXP (ASM_OPERANDS_LABEL (note
, i
), 0) = block_label (target
);
1441 LABEL_NUSES (XEXP (ASM_OPERANDS_LABEL (note
, i
), 0))++;
1442 adjust_jump_target
= true;
1444 if (XEXP (ASM_OPERANDS_LABEL (note
, i
), 0) == BB_HEAD (target
))
1445 asm_goto_edge
= true;
1447 if (adjust_jump_target
)
1449 rtx insn
= BB_END (e
->src
), note
;
1450 rtx old_label
= BB_HEAD (e
->dest
);
1451 rtx new_label
= BB_HEAD (target
);
1453 if (JUMP_LABEL (insn
) == old_label
)
1455 JUMP_LABEL (insn
) = new_label
;
1456 note
= find_reg_note (insn
, REG_LABEL_TARGET
, new_label
);
1458 remove_note (insn
, note
);
1462 note
= find_reg_note (insn
, REG_LABEL_TARGET
, old_label
);
1464 remove_note (insn
, note
);
1465 if (JUMP_LABEL (insn
) != new_label
1466 && !find_reg_note (insn
, REG_LABEL_TARGET
, new_label
))
1467 add_reg_note (insn
, REG_LABEL_TARGET
, new_label
);
1469 while ((note
= find_reg_note (insn
, REG_LABEL_OPERAND
, old_label
))
1471 XEXP (note
, 0) = new_label
;
1475 if (EDGE_COUNT (e
->src
->succs
) >= 2 || abnormal_edge_flags
|| asm_goto_edge
)
1477 gcov_type count
= e
->count
;
1478 int probability
= e
->probability
;
1479 /* Create the new structures. */
1481 /* If the old block ended with a tablejump, skip its table
1482 by searching forward from there. Otherwise start searching
1483 forward from the last instruction of the old block. */
1484 if (!tablejump_p (BB_END (e
->src
), NULL
, ¬e
))
1485 note
= BB_END (e
->src
);
1486 note
= NEXT_INSN (note
);
1488 jump_block
= create_basic_block (note
, NULL
, e
->src
);
1489 jump_block
->count
= count
;
1490 jump_block
->frequency
= EDGE_FREQUENCY (e
);
1492 /* Make sure new block ends up in correct hot/cold section. */
1494 BB_COPY_PARTITION (jump_block
, e
->src
);
1495 if (flag_reorder_blocks_and_partition
1496 && targetm_common
.have_named_sections
1497 && JUMP_P (BB_END (jump_block
))
1498 && !any_condjump_p (BB_END (jump_block
))
1499 && (EDGE_SUCC (jump_block
, 0)->flags
& EDGE_CROSSING
))
1500 add_reg_note (BB_END (jump_block
), REG_CROSSING_JUMP
, NULL_RTX
);
1503 new_edge
= make_edge (e
->src
, jump_block
, EDGE_FALLTHRU
);
1504 new_edge
->probability
= probability
;
1505 new_edge
->count
= count
;
1507 /* Redirect old edge. */
1508 redirect_edge_pred (e
, jump_block
);
1509 e
->probability
= REG_BR_PROB_BASE
;
1511 /* If asm goto has any label refs to target's label,
1512 add also edge from asm goto bb to target. */
1515 new_edge
->probability
/= 2;
1516 new_edge
->count
/= 2;
1517 jump_block
->count
/= 2;
1518 jump_block
->frequency
/= 2;
1519 new_edge
= make_edge (new_edge
->src
, target
,
1520 e
->flags
& ~EDGE_FALLTHRU
);
1521 new_edge
->probability
= probability
- probability
/ 2;
1522 new_edge
->count
= count
- count
/ 2;
1525 new_bb
= jump_block
;
1528 jump_block
= e
->src
;
1530 loc
= e
->goto_locus
;
1531 e
->flags
&= ~EDGE_FALLTHRU
;
1532 if (target
== EXIT_BLOCK_PTR
)
1534 if (jump_label
== ret_rtx
)
1537 emit_jump_insn_after_setloc (gen_return (), BB_END (jump_block
), loc
);
1544 gcc_assert (jump_label
== simple_return_rtx
);
1545 #ifdef HAVE_simple_return
1546 emit_jump_insn_after_setloc (gen_simple_return (),
1547 BB_END (jump_block
), loc
);
1552 set_return_jump_label (BB_END (jump_block
));
1556 rtx label
= block_label (target
);
1557 emit_jump_insn_after_setloc (gen_jump (label
), BB_END (jump_block
), loc
);
1558 JUMP_LABEL (BB_END (jump_block
)) = label
;
1559 LABEL_NUSES (label
)++;
1562 emit_barrier_after (BB_END (jump_block
));
1563 redirect_edge_succ_nodup (e
, target
);
1565 if (abnormal_edge_flags
)
1566 make_edge (src
, target
, abnormal_edge_flags
);
1568 df_mark_solutions_dirty ();
1572 /* Edge E is assumed to be fallthru edge. Emit needed jump instruction
1573 (and possibly create new basic block) to make edge non-fallthru.
1574 Return newly created BB or NULL if none. */
1577 rtl_force_nonfallthru (edge e
)
1579 return force_nonfallthru_and_redirect (e
, e
->dest
, NULL_RTX
);
1582 /* Redirect edge even at the expense of creating new jump insn or
1583 basic block. Return new basic block if created, NULL otherwise.
1584 Conversion must be possible. */
1587 rtl_redirect_edge_and_branch_force (edge e
, basic_block target
)
1589 if (redirect_edge_and_branch (e
, target
)
1590 || e
->dest
== target
)
1593 /* In case the edge redirection failed, try to force it to be non-fallthru
1594 and redirect newly created simplejump. */
1595 df_set_bb_dirty (e
->src
);
1596 return force_nonfallthru_and_redirect (e
, target
, NULL_RTX
);
1599 /* The given edge should potentially be a fallthru edge. If that is in
1600 fact true, delete the jump and barriers that are in the way. */
1603 rtl_tidy_fallthru_edge (edge e
)
1606 basic_block b
= e
->src
, c
= b
->next_bb
;
1608 /* ??? In a late-running flow pass, other folks may have deleted basic
1609 blocks by nopping out blocks, leaving multiple BARRIERs between here
1610 and the target label. They ought to be chastised and fixed.
1612 We can also wind up with a sequence of undeletable labels between
1613 one block and the next.
1615 So search through a sequence of barriers, labels, and notes for
1616 the head of block C and assert that we really do fall through. */
1618 for (q
= NEXT_INSN (BB_END (b
)); q
!= BB_HEAD (c
); q
= NEXT_INSN (q
))
1622 /* Remove what will soon cease being the jump insn from the source block.
1623 If block B consisted only of this single jump, turn it into a deleted
1628 && (any_uncondjump_p (q
)
1629 || single_succ_p (b
)))
1632 /* If this was a conditional jump, we need to also delete
1633 the insn that set cc0. */
1634 if (any_condjump_p (q
) && only_sets_cc0_p (PREV_INSN (q
)))
1641 /* Selectively unlink the sequence. */
1642 if (q
!= PREV_INSN (BB_HEAD (c
)))
1643 delete_insn_chain (NEXT_INSN (q
), PREV_INSN (BB_HEAD (c
)), false);
1645 e
->flags
|= EDGE_FALLTHRU
;
1648 /* Should move basic block BB after basic block AFTER. NIY. */
1651 rtl_move_block_after (basic_block bb ATTRIBUTE_UNUSED
,
1652 basic_block after ATTRIBUTE_UNUSED
)
1657 /* Split a (typically critical) edge. Return the new block.
1658 The edge must not be abnormal.
1660 ??? The code generally expects to be called on critical edges.
1661 The case of a block ending in an unconditional jump to a
1662 block with multiple predecessors is not handled optimally. */
1665 rtl_split_edge (edge edge_in
)
1670 /* Abnormal edges cannot be split. */
1671 gcc_assert (!(edge_in
->flags
& EDGE_ABNORMAL
));
1673 /* We are going to place the new block in front of edge destination.
1674 Avoid existence of fallthru predecessors. */
1675 if ((edge_in
->flags
& EDGE_FALLTHRU
) == 0)
1677 edge e
= find_fallthru_edge (edge_in
->dest
->preds
);
1680 force_nonfallthru (e
);
1683 /* Create the basic block note. */
1684 if (edge_in
->dest
!= EXIT_BLOCK_PTR
)
1685 before
= BB_HEAD (edge_in
->dest
);
1689 /* If this is a fall through edge to the exit block, the blocks might be
1690 not adjacent, and the right place is after the source. */
1691 if ((edge_in
->flags
& EDGE_FALLTHRU
) && edge_in
->dest
== EXIT_BLOCK_PTR
)
1693 before
= NEXT_INSN (BB_END (edge_in
->src
));
1694 bb
= create_basic_block (before
, NULL
, edge_in
->src
);
1695 BB_COPY_PARTITION (bb
, edge_in
->src
);
1699 bb
= create_basic_block (before
, NULL
, edge_in
->dest
->prev_bb
);
1700 /* ??? Why not edge_in->dest->prev_bb here? */
1701 BB_COPY_PARTITION (bb
, edge_in
->dest
);
1704 make_single_succ_edge (bb
, edge_in
->dest
, EDGE_FALLTHRU
);
1706 /* For non-fallthru edges, we must adjust the predecessor's
1707 jump instruction to target our new block. */
1708 if ((edge_in
->flags
& EDGE_FALLTHRU
) == 0)
1710 edge redirected
= redirect_edge_and_branch (edge_in
, bb
);
1711 gcc_assert (redirected
);
1715 if (edge_in
->src
!= ENTRY_BLOCK_PTR
)
1717 /* For asm goto even splitting of fallthru edge might
1718 need insn patching, as other labels might point to the
1720 rtx last
= BB_END (edge_in
->src
);
1723 && edge_in
->dest
!= EXIT_BLOCK_PTR
1724 && extract_asm_operands (PATTERN (last
)) != NULL_RTX
1725 && patch_jump_insn (last
, before
, bb
))
1726 df_set_bb_dirty (edge_in
->src
);
1728 redirect_edge_succ (edge_in
, bb
);
1734 /* Queue instructions for insertion on an edge between two basic blocks.
1735 The new instructions and basic blocks (if any) will not appear in the
1736 CFG until commit_edge_insertions is called. */
1739 insert_insn_on_edge (rtx pattern
, edge e
)
1741 /* We cannot insert instructions on an abnormal critical edge.
1742 It will be easier to find the culprit if we die now. */
1743 gcc_assert (!((e
->flags
& EDGE_ABNORMAL
) && EDGE_CRITICAL_P (e
)));
1745 if (e
->insns
.r
== NULL_RTX
)
1748 push_to_sequence (e
->insns
.r
);
1750 emit_insn (pattern
);
1752 e
->insns
.r
= get_insns ();
1756 /* Update the CFG for the instructions queued on edge E. */
1759 commit_one_edge_insertion (edge e
)
1761 rtx before
= NULL_RTX
, after
= NULL_RTX
, insns
, tmp
, last
;
1764 /* Pull the insns off the edge now since the edge might go away. */
1766 e
->insns
.r
= NULL_RTX
;
1768 /* Figure out where to put these insns. If the destination has
1769 one predecessor, insert there. Except for the exit block. */
1770 if (single_pred_p (e
->dest
) && e
->dest
!= EXIT_BLOCK_PTR
)
1774 /* Get the location correct wrt a code label, and "nice" wrt
1775 a basic block note, and before everything else. */
1778 tmp
= NEXT_INSN (tmp
);
1779 if (NOTE_INSN_BASIC_BLOCK_P (tmp
))
1780 tmp
= NEXT_INSN (tmp
);
1781 if (tmp
== BB_HEAD (bb
))
1784 after
= PREV_INSN (tmp
);
1786 after
= get_last_insn ();
1789 /* If the source has one successor and the edge is not abnormal,
1790 insert there. Except for the entry block. */
1791 else if ((e
->flags
& EDGE_ABNORMAL
) == 0
1792 && single_succ_p (e
->src
)
1793 && e
->src
!= ENTRY_BLOCK_PTR
)
1797 /* It is possible to have a non-simple jump here. Consider a target
1798 where some forms of unconditional jumps clobber a register. This
1799 happens on the fr30 for example.
1801 We know this block has a single successor, so we can just emit
1802 the queued insns before the jump. */
1803 if (JUMP_P (BB_END (bb
)))
1804 before
= BB_END (bb
);
1807 /* We'd better be fallthru, or we've lost track of what's what. */
1808 gcc_assert (e
->flags
& EDGE_FALLTHRU
);
1810 after
= BB_END (bb
);
1814 /* Otherwise we must split the edge. */
1817 bb
= split_edge (e
);
1818 after
= BB_END (bb
);
1820 if (flag_reorder_blocks_and_partition
1821 && targetm_common
.have_named_sections
1822 && e
->src
!= ENTRY_BLOCK_PTR
1823 && BB_PARTITION (e
->src
) == BB_COLD_PARTITION
1824 && !(e
->flags
& EDGE_CROSSING
)
1826 && !any_condjump_p (after
)
1827 && (single_succ_edge (bb
)->flags
& EDGE_CROSSING
))
1828 add_reg_note (after
, REG_CROSSING_JUMP
, NULL_RTX
);
1831 /* Now that we've found the spot, do the insertion. */
1834 emit_insn_before_noloc (insns
, before
, bb
);
1835 last
= prev_nonnote_insn (before
);
1838 last
= emit_insn_after_noloc (insns
, after
, bb
);
1840 if (returnjump_p (last
))
1842 /* ??? Remove all outgoing edges from BB and add one for EXIT.
1843 This is not currently a problem because this only happens
1844 for the (single) epilogue, which already has a fallthru edge
1847 e
= single_succ_edge (bb
);
1848 gcc_assert (e
->dest
== EXIT_BLOCK_PTR
1849 && single_succ_p (bb
) && (e
->flags
& EDGE_FALLTHRU
));
1851 e
->flags
&= ~EDGE_FALLTHRU
;
1852 emit_barrier_after (last
);
1855 delete_insn (before
);
1858 gcc_assert (!JUMP_P (last
));
1861 /* Update the CFG for all queued instructions. */
1864 commit_edge_insertions (void)
1868 #ifdef ENABLE_CHECKING
1869 verify_flow_info ();
1872 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
, EXIT_BLOCK_PTR
, next_bb
)
1877 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
1879 commit_one_edge_insertion (e
);
1884 /* Print out RTL-specific basic block information (live information
1885 at start and end with TDF_DETAILS). FLAGS are the TDF_* masks
1886 documented in dumpfile.h. */
1889 rtl_dump_bb (FILE *outf
, basic_block bb
, int indent
, int flags
)
1895 s_indent
= (char *) alloca ((size_t) indent
+ 1);
1896 memset (s_indent
, ' ', (size_t) indent
);
1897 s_indent
[indent
] = '\0';
1899 if (df
&& (flags
& TDF_DETAILS
))
1901 df_dump_top (bb
, outf
);
1905 if (bb
->index
!= ENTRY_BLOCK
&& bb
->index
!= EXIT_BLOCK
)
1906 for (insn
= BB_HEAD (bb
), last
= NEXT_INSN (BB_END (bb
)); insn
!= last
;
1907 insn
= NEXT_INSN (insn
))
1909 if (flags
& TDF_DETAILS
)
1910 df_dump_insn_top (insn
, outf
);
1911 if (! (flags
& TDF_SLIM
))
1912 print_rtl_single (outf
, insn
);
1914 dump_insn_slim (outf
, insn
);
1915 if (flags
& TDF_DETAILS
)
1916 df_dump_insn_bottom (insn
, outf
);
1919 if (df
&& (flags
& TDF_DETAILS
))
1921 df_dump_bottom (bb
, outf
);
1927 /* Like dump_function_to_file, but for RTL. Print out dataflow information
1928 for the start of each basic block. FLAGS are the TDF_* masks documented
1932 print_rtl_with_bb (FILE *outf
, const_rtx rtx_first
, int flags
)
1936 fprintf (outf
, "(nil)\n");
1939 enum bb_state
{ NOT_IN_BB
, IN_ONE_BB
, IN_MULTIPLE_BB
};
1940 int max_uid
= get_max_uid ();
1941 basic_block
*start
= XCNEWVEC (basic_block
, max_uid
);
1942 basic_block
*end
= XCNEWVEC (basic_block
, max_uid
);
1943 enum bb_state
*in_bb_p
= XCNEWVEC (enum bb_state
, max_uid
);
1946 /* After freeing the CFG, we still have BLOCK_FOR_INSN set on most
1947 insns, but the CFG is not maintained so the basic block info
1948 is not reliable. Therefore it's omitted from the dumps. */
1949 if (! (cfun
->curr_properties
& PROP_cfg
))
1950 flags
&= ~TDF_BLOCKS
;
1953 df_dump_start (outf
);
1955 if (flags
& TDF_BLOCKS
)
1957 FOR_EACH_BB_REVERSE (bb
)
1961 start
[INSN_UID (BB_HEAD (bb
))] = bb
;
1962 end
[INSN_UID (BB_END (bb
))] = bb
;
1963 for (x
= BB_HEAD (bb
); x
!= NULL_RTX
; x
= NEXT_INSN (x
))
1965 enum bb_state state
= IN_MULTIPLE_BB
;
1967 if (in_bb_p
[INSN_UID (x
)] == NOT_IN_BB
)
1969 in_bb_p
[INSN_UID (x
)] = state
;
1971 if (x
== BB_END (bb
))
1977 for (tmp_rtx
= rtx_first
; NULL
!= tmp_rtx
; tmp_rtx
= NEXT_INSN (tmp_rtx
))
1979 if (flags
& TDF_BLOCKS
)
1981 bb
= start
[INSN_UID (tmp_rtx
)];
1984 dump_bb_info (outf
, bb
, 0, dump_flags
| TDF_COMMENT
, true, false);
1985 if (df
&& (flags
& TDF_DETAILS
))
1986 df_dump_top (bb
, outf
);
1989 if (in_bb_p
[INSN_UID (tmp_rtx
)] == NOT_IN_BB
1990 && !NOTE_P (tmp_rtx
)
1991 && !BARRIER_P (tmp_rtx
))
1992 fprintf (outf
, ";; Insn is not within a basic block\n");
1993 else if (in_bb_p
[INSN_UID (tmp_rtx
)] == IN_MULTIPLE_BB
)
1994 fprintf (outf
, ";; Insn is in multiple basic blocks\n");
1997 if (flags
& TDF_DETAILS
)
1998 df_dump_insn_top (tmp_rtx
, outf
);
1999 if (! (flags
& TDF_SLIM
))
2000 print_rtl_single (outf
, tmp_rtx
);
2002 dump_insn_slim (outf
, tmp_rtx
);
2003 if (flags
& TDF_DETAILS
)
2004 df_dump_insn_bottom (tmp_rtx
, outf
);
2006 if (flags
& TDF_BLOCKS
)
2008 bb
= end
[INSN_UID (tmp_rtx
)];
2011 dump_bb_info (outf
, bb
, 0, dump_flags
| TDF_COMMENT
, false, true);
2012 if (df
&& (flags
& TDF_DETAILS
))
2013 df_dump_bottom (bb
, outf
);
2025 /* Update the branch probability of BB if a REG_BR_PROB is present. */
2028 update_br_prob_note (basic_block bb
)
2031 if (!JUMP_P (BB_END (bb
)))
2033 note
= find_reg_note (BB_END (bb
), REG_BR_PROB
, NULL_RTX
);
2034 if (!note
|| INTVAL (XEXP (note
, 0)) == BRANCH_EDGE (bb
)->probability
)
2036 XEXP (note
, 0) = GEN_INT (BRANCH_EDGE (bb
)->probability
);
2039 /* Get the last insn associated with block BB (that includes barriers and
2040 tablejumps after BB). */
2042 get_last_bb_insn (basic_block bb
)
2045 rtx end
= BB_END (bb
);
2047 /* Include any jump table following the basic block. */
2048 if (tablejump_p (end
, NULL
, &tmp
))
2051 /* Include any barriers that may follow the basic block. */
2052 tmp
= next_nonnote_insn_bb (end
);
2053 while (tmp
&& BARRIER_P (tmp
))
2056 tmp
= next_nonnote_insn_bb (end
);
2062 /* Verify the CFG and RTL consistency common for both underlying RTL and
2065 Currently it does following checks:
2067 - overlapping of basic blocks
2068 - insns with wrong BLOCK_FOR_INSN pointers
2069 - headers of basic blocks (the NOTE_INSN_BASIC_BLOCK note)
2070 - tails of basic blocks (ensure that boundary is necessary)
2071 - scans body of the basic block for JUMP_INSN, CODE_LABEL
2072 and NOTE_INSN_BASIC_BLOCK
2073 - verify that no fall_thru edge crosses hot/cold partition boundaries
2074 - verify that there are no pending RTL branch predictions
2076 In future it can be extended check a lot of other stuff as well
2077 (reachability of basic blocks, life information, etc. etc.). */
2080 rtl_verify_flow_info_1 (void)
2086 /* Check the general integrity of the basic blocks. */
2087 FOR_EACH_BB_REVERSE (bb
)
2091 if (!(bb
->flags
& BB_RTL
))
2093 error ("BB_RTL flag not set for block %d", bb
->index
);
2097 FOR_BB_INSNS (bb
, insn
)
2098 if (BLOCK_FOR_INSN (insn
) != bb
)
2100 error ("insn %d basic block pointer is %d, should be %d",
2102 BLOCK_FOR_INSN (insn
) ? BLOCK_FOR_INSN (insn
)->index
: 0,
2107 for (insn
= BB_HEADER (bb
); insn
; insn
= NEXT_INSN (insn
))
2108 if (!BARRIER_P (insn
)
2109 && BLOCK_FOR_INSN (insn
) != NULL
)
2111 error ("insn %d in header of bb %d has non-NULL basic block",
2112 INSN_UID (insn
), bb
->index
);
2115 for (insn
= BB_FOOTER (bb
); insn
; insn
= NEXT_INSN (insn
))
2116 if (!BARRIER_P (insn
)
2117 && BLOCK_FOR_INSN (insn
) != NULL
)
2119 error ("insn %d in footer of bb %d has non-NULL basic block",
2120 INSN_UID (insn
), bb
->index
);
2125 /* Now check the basic blocks (boundaries etc.) */
2126 FOR_EACH_BB_REVERSE (bb
)
2128 int n_fallthru
= 0, n_branch
= 0, n_abnormal_call
= 0, n_sibcall
= 0;
2129 int n_eh
= 0, n_abnormal
= 0;
2130 edge e
, fallthru
= NULL
;
2134 if (JUMP_P (BB_END (bb
))
2135 && (note
= find_reg_note (BB_END (bb
), REG_BR_PROB
, NULL_RTX
))
2136 && EDGE_COUNT (bb
->succs
) >= 2
2137 && any_condjump_p (BB_END (bb
)))
2139 if (INTVAL (XEXP (note
, 0)) != BRANCH_EDGE (bb
)->probability
2140 && profile_status
!= PROFILE_ABSENT
)
2142 error ("verify_flow_info: REG_BR_PROB does not match cfg %wi %i",
2143 INTVAL (XEXP (note
, 0)), BRANCH_EDGE (bb
)->probability
);
2147 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
2151 if (e
->flags
& EDGE_FALLTHRU
)
2152 n_fallthru
++, fallthru
= e
;
2154 is_crossing
= (BB_PARTITION (e
->src
) != BB_PARTITION (e
->dest
)
2155 && e
->src
!= ENTRY_BLOCK_PTR
2156 && e
->dest
!= EXIT_BLOCK_PTR
);
2157 if (e
->flags
& EDGE_CROSSING
)
2161 error ("EDGE_CROSSING incorrectly set across same section");
2164 if (e
->flags
& EDGE_FALLTHRU
)
2166 error ("fallthru edge crosses section boundary in bb %i",
2170 if (e
->flags
& EDGE_EH
)
2172 error ("EH edge crosses section boundary in bb %i",
2177 else if (is_crossing
)
2179 error ("EDGE_CROSSING missing across section boundary");
2183 if ((e
->flags
& ~(EDGE_DFS_BACK
2185 | EDGE_IRREDUCIBLE_LOOP
2188 | EDGE_PRESERVE
)) == 0)
2191 if (e
->flags
& EDGE_ABNORMAL_CALL
)
2194 if (e
->flags
& EDGE_SIBCALL
)
2197 if (e
->flags
& EDGE_EH
)
2200 if (e
->flags
& EDGE_ABNORMAL
)
2204 if (n_eh
&& !find_reg_note (BB_END (bb
), REG_EH_REGION
, NULL_RTX
))
2206 error ("missing REG_EH_REGION note at the end of bb %i", bb
->index
);
2211 error ("too many exception handling edges in bb %i", bb
->index
);
2215 && (!JUMP_P (BB_END (bb
))
2216 || (n_branch
> 1 && (any_uncondjump_p (BB_END (bb
))
2217 || any_condjump_p (BB_END (bb
))))))
2219 error ("too many outgoing branch edges from bb %i", bb
->index
);
2222 if (n_fallthru
&& any_uncondjump_p (BB_END (bb
)))
2224 error ("fallthru edge after unconditional jump in bb %i", bb
->index
);
2227 if (n_branch
!= 1 && any_uncondjump_p (BB_END (bb
)))
2229 error ("wrong number of branch edges after unconditional jump"
2230 " in bb %i", bb
->index
);
2233 if (n_branch
!= 1 && any_condjump_p (BB_END (bb
))
2234 && JUMP_LABEL (BB_END (bb
)) != BB_HEAD (fallthru
->dest
))
2236 error ("wrong amount of branch edges after conditional jump"
2237 " in bb %i", bb
->index
);
2240 if (n_abnormal_call
&& !CALL_P (BB_END (bb
)))
2242 error ("abnormal call edges for non-call insn in bb %i", bb
->index
);
2245 if (n_sibcall
&& !CALL_P (BB_END (bb
)))
2247 error ("sibcall edges for non-call insn in bb %i", bb
->index
);
2250 if (n_abnormal
> n_eh
2251 && !(CALL_P (BB_END (bb
))
2252 && n_abnormal
== n_abnormal_call
+ n_sibcall
)
2253 && (!JUMP_P (BB_END (bb
))
2254 || any_condjump_p (BB_END (bb
))
2255 || any_uncondjump_p (BB_END (bb
))))
2257 error ("abnormal edges for no purpose in bb %i", bb
->index
);
2261 for (x
= BB_HEAD (bb
); x
!= NEXT_INSN (BB_END (bb
)); x
= NEXT_INSN (x
))
2262 /* We may have a barrier inside a basic block before dead code
2263 elimination. There is no BLOCK_FOR_INSN field in a barrier. */
2264 if (!BARRIER_P (x
) && BLOCK_FOR_INSN (x
) != bb
)
2267 if (! BLOCK_FOR_INSN (x
))
2269 ("insn %d inside basic block %d but block_for_insn is NULL",
2270 INSN_UID (x
), bb
->index
);
2273 ("insn %d inside basic block %d but block_for_insn is %i",
2274 INSN_UID (x
), bb
->index
, BLOCK_FOR_INSN (x
)->index
);
2279 /* OK pointers are correct. Now check the header of basic
2280 block. It ought to contain optional CODE_LABEL followed
2281 by NOTE_BASIC_BLOCK. */
2285 if (BB_END (bb
) == x
)
2287 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
2295 if (!NOTE_INSN_BASIC_BLOCK_P (x
) || NOTE_BASIC_BLOCK (x
) != bb
)
2297 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
2302 if (BB_END (bb
) == x
)
2303 /* Do checks for empty blocks here. */
2306 for (x
= NEXT_INSN (x
); x
; x
= NEXT_INSN (x
))
2308 if (NOTE_INSN_BASIC_BLOCK_P (x
))
2310 error ("NOTE_INSN_BASIC_BLOCK %d in middle of basic block %d",
2311 INSN_UID (x
), bb
->index
);
2315 if (x
== BB_END (bb
))
2318 if (control_flow_insn_p (x
))
2320 error ("in basic block %d:", bb
->index
);
2321 fatal_insn ("flow control insn inside a basic block", x
);
2330 /* Verify the CFG and RTL consistency common for both underlying RTL and
2333 Currently it does following checks:
2334 - all checks of rtl_verify_flow_info_1
2335 - test head/end pointers
2336 - check that all insns are in the basic blocks
2337 (except the switch handling code, barriers and notes)
2338 - check that all returns are followed by barriers
2339 - check that all fallthru edge points to the adjacent blocks. */
2342 rtl_verify_flow_info (void)
2345 int err
= rtl_verify_flow_info_1 ();
2347 rtx last_head
= get_last_insn ();
2348 basic_block
*bb_info
;
2350 const rtx rtx_first
= get_insns ();
2351 basic_block last_bb_seen
= ENTRY_BLOCK_PTR
, curr_bb
= NULL
;
2352 const int max_uid
= get_max_uid ();
2354 bb_info
= XCNEWVEC (basic_block
, max_uid
);
2356 FOR_EACH_BB_REVERSE (bb
)
2359 rtx head
= BB_HEAD (bb
);
2360 rtx end
= BB_END (bb
);
2362 for (x
= last_head
; x
!= NULL_RTX
; x
= PREV_INSN (x
))
2364 /* Verify the end of the basic block is in the INSN chain. */
2368 /* And that the code outside of basic blocks has NULL bb field. */
2370 && BLOCK_FOR_INSN (x
) != NULL
)
2372 error ("insn %d outside of basic blocks has non-NULL bb field",
2380 error ("end insn %d for block %d not found in the insn stream",
2381 INSN_UID (end
), bb
->index
);
2385 /* Work backwards from the end to the head of the basic block
2386 to verify the head is in the RTL chain. */
2387 for (; x
!= NULL_RTX
; x
= PREV_INSN (x
))
2389 /* While walking over the insn chain, verify insns appear
2390 in only one basic block. */
2391 if (bb_info
[INSN_UID (x
)] != NULL
)
2393 error ("insn %d is in multiple basic blocks (%d and %d)",
2394 INSN_UID (x
), bb
->index
, bb_info
[INSN_UID (x
)]->index
);
2398 bb_info
[INSN_UID (x
)] = bb
;
2405 error ("head insn %d for block %d not found in the insn stream",
2406 INSN_UID (head
), bb
->index
);
2410 last_head
= PREV_INSN (x
);
2412 e
= find_fallthru_edge (bb
->succs
);
2417 /* Ensure existence of barrier in BB with no fallthru edges. */
2418 for (insn
= NEXT_INSN (BB_END (bb
)); ; insn
= NEXT_INSN (insn
))
2420 if (!insn
|| NOTE_INSN_BASIC_BLOCK_P (insn
))
2422 error ("missing barrier after block %i", bb
->index
);
2426 if (BARRIER_P (insn
))
2430 else if (e
->src
!= ENTRY_BLOCK_PTR
2431 && e
->dest
!= EXIT_BLOCK_PTR
)
2435 if (e
->src
->next_bb
!= e
->dest
)
2438 ("verify_flow_info: Incorrect blocks for fallthru %i->%i",
2439 e
->src
->index
, e
->dest
->index
);
2443 for (insn
= NEXT_INSN (BB_END (e
->src
)); insn
!= BB_HEAD (e
->dest
);
2444 insn
= NEXT_INSN (insn
))
2445 if (BARRIER_P (insn
) || INSN_P (insn
))
2447 error ("verify_flow_info: Incorrect fallthru %i->%i",
2448 e
->src
->index
, e
->dest
->index
);
2449 fatal_insn ("wrong insn in the fallthru edge", insn
);
2455 for (x
= last_head
; x
!= NULL_RTX
; x
= PREV_INSN (x
))
2457 /* Check that the code before the first basic block has NULL
2460 && BLOCK_FOR_INSN (x
) != NULL
)
2462 error ("insn %d outside of basic blocks has non-NULL bb field",
2470 last_bb_seen
= ENTRY_BLOCK_PTR
;
2472 for (x
= rtx_first
; x
; x
= NEXT_INSN (x
))
2474 if (NOTE_INSN_BASIC_BLOCK_P (x
))
2476 bb
= NOTE_BASIC_BLOCK (x
);
2479 if (bb
!= last_bb_seen
->next_bb
)
2480 internal_error ("basic blocks not laid down consecutively");
2482 curr_bb
= last_bb_seen
= bb
;
2487 switch (GET_CODE (x
))
2494 /* An ADDR_VEC is placed outside any basic block. */
2496 && JUMP_TABLE_DATA_P (NEXT_INSN (x
)))
2499 /* But in any case, non-deletable labels can appear anywhere. */
2503 fatal_insn ("insn outside basic block", x
);
2508 && returnjump_p (x
) && ! condjump_p (x
)
2509 && ! (next_nonnote_insn (x
) && BARRIER_P (next_nonnote_insn (x
))))
2510 fatal_insn ("return not followed by barrier", x
);
2511 if (curr_bb
&& x
== BB_END (curr_bb
))
2515 if (num_bb_notes
!= n_basic_blocks
- NUM_FIXED_BLOCKS
)
2517 ("number of bb notes in insn chain (%d) != n_basic_blocks (%d)",
2518 num_bb_notes
, n_basic_blocks
);
2523 /* Assume that the preceding pass has possibly eliminated jump instructions
2524 or converted the unconditional jumps. Eliminate the edges from CFG.
2525 Return true if any edges are eliminated. */
2528 purge_dead_edges (basic_block bb
)
2531 rtx insn
= BB_END (bb
), note
;
2532 bool purged
= false;
2536 if (DEBUG_INSN_P (insn
) && insn
!= BB_HEAD (bb
))
2538 insn
= PREV_INSN (insn
);
2539 while ((DEBUG_INSN_P (insn
) || NOTE_P (insn
)) && insn
!= BB_HEAD (bb
));
2541 /* If this instruction cannot trap, remove REG_EH_REGION notes. */
2542 if (NONJUMP_INSN_P (insn
)
2543 && (note
= find_reg_note (insn
, REG_EH_REGION
, NULL
)))
2547 if (! may_trap_p (PATTERN (insn
))
2548 || ((eqnote
= find_reg_equal_equiv_note (insn
))
2549 && ! may_trap_p (XEXP (eqnote
, 0))))
2550 remove_note (insn
, note
);
2553 /* Cleanup abnormal edges caused by exceptions or non-local gotos. */
2554 for (ei
= ei_start (bb
->succs
); (e
= ei_safe_edge (ei
)); )
2556 bool remove
= false;
2558 /* There are three types of edges we need to handle correctly here: EH
2559 edges, abnormal call EH edges, and abnormal call non-EH edges. The
2560 latter can appear when nonlocal gotos are used. */
2561 if (e
->flags
& EDGE_ABNORMAL_CALL
)
2565 else if (can_nonlocal_goto (insn
))
2567 else if ((e
->flags
& EDGE_EH
) && can_throw_internal (insn
))
2569 else if (flag_tm
&& find_reg_note (insn
, REG_TM
, NULL
))
2574 else if (e
->flags
& EDGE_EH
)
2575 remove
= !can_throw_internal (insn
);
2580 df_set_bb_dirty (bb
);
2593 /* We do care only about conditional jumps and simplejumps. */
2594 if (!any_condjump_p (insn
)
2595 && !returnjump_p (insn
)
2596 && !simplejump_p (insn
))
2599 /* Branch probability/prediction notes are defined only for
2600 condjumps. We've possibly turned condjump into simplejump. */
2601 if (simplejump_p (insn
))
2603 note
= find_reg_note (insn
, REG_BR_PROB
, NULL
);
2605 remove_note (insn
, note
);
2606 while ((note
= find_reg_note (insn
, REG_BR_PRED
, NULL
)))
2607 remove_note (insn
, note
);
2610 for (ei
= ei_start (bb
->succs
); (e
= ei_safe_edge (ei
)); )
2612 /* Avoid abnormal flags to leak from computed jumps turned
2613 into simplejumps. */
2615 e
->flags
&= ~EDGE_ABNORMAL
;
2617 /* See if this edge is one we should keep. */
2618 if ((e
->flags
& EDGE_FALLTHRU
) && any_condjump_p (insn
))
2619 /* A conditional jump can fall through into the next
2620 block, so we should keep the edge. */
2625 else if (e
->dest
!= EXIT_BLOCK_PTR
2626 && BB_HEAD (e
->dest
) == JUMP_LABEL (insn
))
2627 /* If the destination block is the target of the jump,
2633 else if (e
->dest
== EXIT_BLOCK_PTR
&& returnjump_p (insn
))
2634 /* If the destination block is the exit block, and this
2635 instruction is a return, then keep the edge. */
2640 else if ((e
->flags
& EDGE_EH
) && can_throw_internal (insn
))
2641 /* Keep the edges that correspond to exceptions thrown by
2642 this instruction and rematerialize the EDGE_ABNORMAL
2643 flag we just cleared above. */
2645 e
->flags
|= EDGE_ABNORMAL
;
2650 /* We do not need this edge. */
2651 df_set_bb_dirty (bb
);
2656 if (EDGE_COUNT (bb
->succs
) == 0 || !purged
)
2660 fprintf (dump_file
, "Purged edges from bb %i\n", bb
->index
);
2665 /* Redistribute probabilities. */
2666 if (single_succ_p (bb
))
2668 single_succ_edge (bb
)->probability
= REG_BR_PROB_BASE
;
2669 single_succ_edge (bb
)->count
= bb
->count
;
2673 note
= find_reg_note (insn
, REG_BR_PROB
, NULL
);
2677 b
= BRANCH_EDGE (bb
);
2678 f
= FALLTHRU_EDGE (bb
);
2679 b
->probability
= INTVAL (XEXP (note
, 0));
2680 f
->probability
= REG_BR_PROB_BASE
- b
->probability
;
2681 /* Update these to use GCOV_COMPUTE_SCALE. */
2682 b
->count
= bb
->count
* b
->probability
/ REG_BR_PROB_BASE
;
2683 f
->count
= bb
->count
* f
->probability
/ REG_BR_PROB_BASE
;
2688 else if (CALL_P (insn
) && SIBLING_CALL_P (insn
))
2690 /* First, there should not be any EH or ABCALL edges resulting
2691 from non-local gotos and the like. If there were, we shouldn't
2692 have created the sibcall in the first place. Second, there
2693 should of course never have been a fallthru edge. */
2694 gcc_assert (single_succ_p (bb
));
2695 gcc_assert (single_succ_edge (bb
)->flags
2696 == (EDGE_SIBCALL
| EDGE_ABNORMAL
));
2701 /* If we don't see a jump insn, we don't know exactly why the block would
2702 have been broken at this point. Look for a simple, non-fallthru edge,
2703 as these are only created by conditional branches. If we find such an
2704 edge we know that there used to be a jump here and can then safely
2705 remove all non-fallthru edges. */
2707 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
2708 if (! (e
->flags
& (EDGE_COMPLEX
| EDGE_FALLTHRU
)))
2717 /* Remove all but the fake and fallthru edges. The fake edge may be
2718 the only successor for this block in the case of noreturn
2720 for (ei
= ei_start (bb
->succs
); (e
= ei_safe_edge (ei
)); )
2722 if (!(e
->flags
& (EDGE_FALLTHRU
| EDGE_FAKE
)))
2724 df_set_bb_dirty (bb
);
2732 gcc_assert (single_succ_p (bb
));
2734 single_succ_edge (bb
)->probability
= REG_BR_PROB_BASE
;
2735 single_succ_edge (bb
)->count
= bb
->count
;
2738 fprintf (dump_file
, "Purged non-fallthru edges from bb %i\n",
2743 /* Search all basic blocks for potentially dead edges and purge them. Return
2744 true if some edge has been eliminated. */
2747 purge_all_dead_edges (void)
2754 bool purged_here
= purge_dead_edges (bb
);
2756 purged
|= purged_here
;
2762 /* This is used by a few passes that emit some instructions after abnormal
2763 calls, moving the basic block's end, while they in fact do want to emit
2764 them on the fallthru edge. Look for abnormal call edges, find backward
2765 the call in the block and insert the instructions on the edge instead.
2767 Similarly, handle instructions throwing exceptions internally.
2769 Return true when instructions have been found and inserted on edges. */
2772 fixup_abnormal_edges (void)
2774 bool inserted
= false;
2782 /* Look for cases we are interested in - calls or instructions causing
2784 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
2785 if ((e
->flags
& EDGE_ABNORMAL_CALL
)
2786 || ((e
->flags
& (EDGE_ABNORMAL
| EDGE_EH
))
2787 == (EDGE_ABNORMAL
| EDGE_EH
)))
2790 if (e
&& !CALL_P (BB_END (bb
)) && !can_throw_internal (BB_END (bb
)))
2794 /* Get past the new insns generated. Allow notes, as the insns
2795 may be already deleted. */
2797 while ((NONJUMP_INSN_P (insn
) || NOTE_P (insn
))
2798 && !can_throw_internal (insn
)
2799 && insn
!= BB_HEAD (bb
))
2800 insn
= PREV_INSN (insn
);
2802 if (CALL_P (insn
) || can_throw_internal (insn
))
2806 e
= find_fallthru_edge (bb
->succs
);
2808 stop
= NEXT_INSN (BB_END (bb
));
2811 for (insn
= NEXT_INSN (insn
); insn
!= stop
; insn
= next
)
2813 next
= NEXT_INSN (insn
);
2818 /* Sometimes there's still the return value USE.
2819 If it's placed after a trapping call (i.e. that
2820 call is the last insn anyway), we have no fallthru
2821 edge. Simply delete this use and don't try to insert
2822 on the non-existent edge. */
2823 if (GET_CODE (PATTERN (insn
)) != USE
)
2825 /* We're not deleting it, we're moving it. */
2826 INSN_DELETED_P (insn
) = 0;
2827 PREV_INSN (insn
) = NULL_RTX
;
2828 NEXT_INSN (insn
) = NULL_RTX
;
2830 insert_insn_on_edge (insn
, e
);
2834 else if (!BARRIER_P (insn
))
2835 set_block_for_insn (insn
, NULL
);
2839 /* It may be that we don't find any trapping insn. In this
2840 case we discovered quite late that the insn that had been
2841 marked as can_throw_internal in fact couldn't trap at all.
2842 So we should in fact delete the EH edges out of the block. */
2844 purge_dead_edges (bb
);
2851 /* Cut the insns from FIRST to LAST out of the insns stream. */
2854 unlink_insn_chain (rtx first
, rtx last
)
2856 rtx prevfirst
= PREV_INSN (first
);
2857 rtx nextlast
= NEXT_INSN (last
);
2859 PREV_INSN (first
) = NULL
;
2860 NEXT_INSN (last
) = NULL
;
2862 NEXT_INSN (prevfirst
) = nextlast
;
2864 PREV_INSN (nextlast
) = prevfirst
;
2866 set_last_insn (prevfirst
);
2868 set_first_insn (nextlast
);
2872 /* Skip over inter-block insns occurring after BB which are typically
2873 associated with BB (e.g., barriers). If there are any such insns,
2874 we return the last one. Otherwise, we return the end of BB. */
2877 skip_insns_after_block (basic_block bb
)
2879 rtx insn
, last_insn
, next_head
, prev
;
2881 next_head
= NULL_RTX
;
2882 if (bb
->next_bb
!= EXIT_BLOCK_PTR
)
2883 next_head
= BB_HEAD (bb
->next_bb
);
2885 for (last_insn
= insn
= BB_END (bb
); (insn
= NEXT_INSN (insn
)) != 0; )
2887 if (insn
== next_head
)
2890 switch (GET_CODE (insn
))
2897 switch (NOTE_KIND (insn
))
2899 case NOTE_INSN_BLOCK_END
:
2909 if (NEXT_INSN (insn
)
2910 && JUMP_TABLE_DATA_P (NEXT_INSN (insn
)))
2912 insn
= NEXT_INSN (insn
);
2925 /* It is possible to hit contradictory sequence. For instance:
2931 Where barrier belongs to jump_insn, but the note does not. This can be
2932 created by removing the basic block originally following
2933 NOTE_INSN_BLOCK_BEG. In such case reorder the notes. */
2935 for (insn
= last_insn
; insn
!= BB_END (bb
); insn
= prev
)
2937 prev
= PREV_INSN (insn
);
2939 switch (NOTE_KIND (insn
))
2941 case NOTE_INSN_BLOCK_END
:
2944 case NOTE_INSN_DELETED
:
2945 case NOTE_INSN_DELETED_LABEL
:
2946 case NOTE_INSN_DELETED_DEBUG_LABEL
:
2949 reorder_insns (insn
, insn
, last_insn
);
2956 /* Locate or create a label for a given basic block. */
2959 label_for_bb (basic_block bb
)
2961 rtx label
= BB_HEAD (bb
);
2963 if (!LABEL_P (label
))
2966 fprintf (dump_file
, "Emitting label for block %d\n", bb
->index
);
2968 label
= block_label (bb
);
2974 /* Locate the effective beginning and end of the insn chain for each
2975 block, as defined by skip_insns_after_block above. */
2978 record_effective_endpoints (void)
2984 for (insn
= get_insns ();
2987 && NOTE_KIND (insn
) != NOTE_INSN_BASIC_BLOCK
;
2988 insn
= NEXT_INSN (insn
))
2990 /* No basic blocks at all? */
2993 if (PREV_INSN (insn
))
2994 cfg_layout_function_header
=
2995 unlink_insn_chain (get_insns (), PREV_INSN (insn
));
2997 cfg_layout_function_header
= NULL_RTX
;
2999 next_insn
= get_insns ();
3004 if (PREV_INSN (BB_HEAD (bb
)) && next_insn
!= BB_HEAD (bb
))
3005 BB_HEADER (bb
) = unlink_insn_chain (next_insn
,
3006 PREV_INSN (BB_HEAD (bb
)));
3007 end
= skip_insns_after_block (bb
);
3008 if (NEXT_INSN (BB_END (bb
)) && BB_END (bb
) != end
)
3009 BB_FOOTER (bb
) = unlink_insn_chain (NEXT_INSN (BB_END (bb
)), end
);
3010 next_insn
= NEXT_INSN (BB_END (bb
));
3013 cfg_layout_function_footer
= next_insn
;
3014 if (cfg_layout_function_footer
)
3015 cfg_layout_function_footer
= unlink_insn_chain (cfg_layout_function_footer
, get_last_insn ());
3019 into_cfg_layout_mode (void)
3021 cfg_layout_initialize (0);
3026 outof_cfg_layout_mode (void)
3031 if (bb
->next_bb
!= EXIT_BLOCK_PTR
)
3032 bb
->aux
= bb
->next_bb
;
3034 cfg_layout_finalize ();
3039 struct rtl_opt_pass pass_into_cfg_layout_mode
=
3043 "into_cfglayout", /* name */
3044 OPTGROUP_NONE
, /* optinfo_flags */
3046 into_cfg_layout_mode
, /* execute */
3049 0, /* static_pass_number */
3051 0, /* properties_required */
3052 PROP_cfglayout
, /* properties_provided */
3053 0, /* properties_destroyed */
3054 0, /* todo_flags_start */
3055 0 /* todo_flags_finish */
3059 struct rtl_opt_pass pass_outof_cfg_layout_mode
=
3063 "outof_cfglayout", /* name */
3064 OPTGROUP_NONE
, /* optinfo_flags */
3066 outof_cfg_layout_mode
, /* execute */
3069 0, /* static_pass_number */
3071 0, /* properties_required */
3072 0, /* properties_provided */
3073 PROP_cfglayout
, /* properties_destroyed */
3074 0, /* todo_flags_start */
3075 0 /* todo_flags_finish */
3080 /* Link the basic blocks in the correct order, compacting the basic
3081 block queue while at it. If STAY_IN_CFGLAYOUT_MODE is false, this
3082 function also clears the basic block header and footer fields.
3084 This function is usually called after a pass (e.g. tracer) finishes
3085 some transformations while in cfglayout mode. The required sequence
3086 of the basic blocks is in a linked list along the bb->aux field.
3087 This functions re-links the basic block prev_bb and next_bb pointers
3088 accordingly, and it compacts and renumbers the blocks.
3090 FIXME: This currently works only for RTL, but the only RTL-specific
3091 bits are the STAY_IN_CFGLAYOUT_MODE bits. The tracer pass was moved
3092 to GIMPLE a long time ago, but it doesn't relink the basic block
3093 chain. It could do that (to give better initial RTL) if this function
3094 is made IR-agnostic (and moved to cfganal.c or cfg.c while at it). */
3097 relink_block_chain (bool stay_in_cfglayout_mode
)
3099 basic_block bb
, prev_bb
;
3102 /* Maybe dump the re-ordered sequence. */
3105 fprintf (dump_file
, "Reordered sequence:\n");
3106 for (bb
= ENTRY_BLOCK_PTR
->next_bb
, index
= NUM_FIXED_BLOCKS
;
3108 bb
= (basic_block
) bb
->aux
, index
++)
3110 fprintf (dump_file
, " %i ", index
);
3111 if (get_bb_original (bb
))
3112 fprintf (dump_file
, "duplicate of %i ",
3113 get_bb_original (bb
)->index
);
3114 else if (forwarder_block_p (bb
)
3115 && !LABEL_P (BB_HEAD (bb
)))
3116 fprintf (dump_file
, "compensation ");
3118 fprintf (dump_file
, "bb %i ", bb
->index
);
3119 fprintf (dump_file
, " [%i]\n", bb
->frequency
);
3123 /* Now reorder the blocks. */
3124 prev_bb
= ENTRY_BLOCK_PTR
;
3125 bb
= ENTRY_BLOCK_PTR
->next_bb
;
3126 for (; bb
; prev_bb
= bb
, bb
= (basic_block
) bb
->aux
)
3128 bb
->prev_bb
= prev_bb
;
3129 prev_bb
->next_bb
= bb
;
3131 prev_bb
->next_bb
= EXIT_BLOCK_PTR
;
3132 EXIT_BLOCK_PTR
->prev_bb
= prev_bb
;
3134 /* Then, clean up the aux fields. */
3138 if (!stay_in_cfglayout_mode
)
3139 BB_HEADER (bb
) = BB_FOOTER (bb
) = NULL
;
3142 /* Maybe reset the original copy tables, they are not valid anymore
3143 when we renumber the basic blocks in compact_blocks. If we are
3144 are going out of cfglayout mode, don't re-allocate the tables. */
3145 free_original_copy_tables ();
3146 if (stay_in_cfglayout_mode
)
3147 initialize_original_copy_tables ();
3149 /* Finally, put basic_block_info in the new order. */
3154 /* Given a reorder chain, rearrange the code to match. */
3157 fixup_reorder_chain (void)
3162 if (cfg_layout_function_header
)
3164 set_first_insn (cfg_layout_function_header
);
3165 insn
= cfg_layout_function_header
;
3166 while (NEXT_INSN (insn
))
3167 insn
= NEXT_INSN (insn
);
3170 /* First do the bulk reordering -- rechain the blocks without regard to
3171 the needed changes to jumps and labels. */
3173 for (bb
= ENTRY_BLOCK_PTR
->next_bb
; bb
; bb
= (basic_block
) bb
->aux
)
3178 NEXT_INSN (insn
) = BB_HEADER (bb
);
3180 set_first_insn (BB_HEADER (bb
));
3181 PREV_INSN (BB_HEADER (bb
)) = insn
;
3182 insn
= BB_HEADER (bb
);
3183 while (NEXT_INSN (insn
))
3184 insn
= NEXT_INSN (insn
);
3187 NEXT_INSN (insn
) = BB_HEAD (bb
);
3189 set_first_insn (BB_HEAD (bb
));
3190 PREV_INSN (BB_HEAD (bb
)) = insn
;
3194 NEXT_INSN (insn
) = BB_FOOTER (bb
);
3195 PREV_INSN (BB_FOOTER (bb
)) = insn
;
3196 while (NEXT_INSN (insn
))
3197 insn
= NEXT_INSN (insn
);
3201 NEXT_INSN (insn
) = cfg_layout_function_footer
;
3202 if (cfg_layout_function_footer
)
3203 PREV_INSN (cfg_layout_function_footer
) = insn
;
3205 while (NEXT_INSN (insn
))
3206 insn
= NEXT_INSN (insn
);
3208 set_last_insn (insn
);
3209 #ifdef ENABLE_CHECKING
3210 verify_insn_chain ();
3213 /* Now add jumps and labels as needed to match the blocks new
3216 for (bb
= ENTRY_BLOCK_PTR
->next_bb
; bb
; bb
= (basic_block
) bb
->aux
)
3218 edge e_fall
, e_taken
, e
;
3220 rtx ret_label
= NULL_RTX
;
3221 basic_block nb
, src_bb
;
3224 if (EDGE_COUNT (bb
->succs
) == 0)
3227 /* Find the old fallthru edge, and another non-EH edge for
3229 e_taken
= e_fall
= NULL
;
3231 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
3232 if (e
->flags
& EDGE_FALLTHRU
)
3234 else if (! (e
->flags
& EDGE_EH
))
3237 bb_end_insn
= BB_END (bb
);
3238 if (JUMP_P (bb_end_insn
))
3240 ret_label
= JUMP_LABEL (bb_end_insn
);
3241 if (any_condjump_p (bb_end_insn
))
3243 /* This might happen if the conditional jump has side
3244 effects and could therefore not be optimized away.
3245 Make the basic block to end with a barrier in order
3246 to prevent rtl_verify_flow_info from complaining. */
3249 gcc_assert (!onlyjump_p (bb_end_insn
)
3250 || returnjump_p (bb_end_insn
));
3251 emit_barrier_after (bb_end_insn
);
3255 /* If the old fallthru is still next, nothing to do. */
3256 if (bb
->aux
== e_fall
->dest
3257 || e_fall
->dest
== EXIT_BLOCK_PTR
)
3260 /* The degenerated case of conditional jump jumping to the next
3261 instruction can happen for jumps with side effects. We need
3262 to construct a forwarder block and this will be done just
3263 fine by force_nonfallthru below. */
3267 /* There is another special case: if *neither* block is next,
3268 such as happens at the very end of a function, then we'll
3269 need to add a new unconditional jump. Choose the taken
3270 edge based on known or assumed probability. */
3271 else if (bb
->aux
!= e_taken
->dest
)
3273 rtx note
= find_reg_note (bb_end_insn
, REG_BR_PROB
, 0);
3276 && INTVAL (XEXP (note
, 0)) < REG_BR_PROB_BASE
/ 2
3277 && invert_jump (bb_end_insn
,
3278 (e_fall
->dest
== EXIT_BLOCK_PTR
3280 : label_for_bb (e_fall
->dest
)), 0))
3282 e_fall
->flags
&= ~EDGE_FALLTHRU
;
3283 gcc_checking_assert (could_fall_through
3284 (e_taken
->src
, e_taken
->dest
));
3285 e_taken
->flags
|= EDGE_FALLTHRU
;
3286 update_br_prob_note (bb
);
3287 e
= e_fall
, e_fall
= e_taken
, e_taken
= e
;
3291 /* If the "jumping" edge is a crossing edge, and the fall
3292 through edge is non-crossing, leave things as they are. */
3293 else if ((e_taken
->flags
& EDGE_CROSSING
)
3294 && !(e_fall
->flags
& EDGE_CROSSING
))
3297 /* Otherwise we can try to invert the jump. This will
3298 basically never fail, however, keep up the pretense. */
3299 else if (invert_jump (bb_end_insn
,
3300 (e_fall
->dest
== EXIT_BLOCK_PTR
3302 : label_for_bb (e_fall
->dest
)), 0))
3304 e_fall
->flags
&= ~EDGE_FALLTHRU
;
3305 gcc_checking_assert (could_fall_through
3306 (e_taken
->src
, e_taken
->dest
));
3307 e_taken
->flags
|= EDGE_FALLTHRU
;
3308 update_br_prob_note (bb
);
3309 if (LABEL_NUSES (ret_label
) == 0
3310 && single_pred_p (e_taken
->dest
))
3311 delete_insn (ret_label
);
3315 else if (extract_asm_operands (PATTERN (bb_end_insn
)) != NULL
)
3317 /* If the old fallthru is still next or if
3318 asm goto doesn't have a fallthru (e.g. when followed by
3319 __builtin_unreachable ()), nothing to do. */
3321 || bb
->aux
== e_fall
->dest
3322 || e_fall
->dest
== EXIT_BLOCK_PTR
)
3325 /* Otherwise we'll have to use the fallthru fixup below. */
3329 /* Otherwise we have some return, switch or computed
3330 jump. In the 99% case, there should not have been a
3332 gcc_assert (returnjump_p (bb_end_insn
) || !e_fall
);
3338 /* No fallthru implies a noreturn function with EH edges, or
3339 something similarly bizarre. In any case, we don't need to
3344 /* If the fallthru block is still next, nothing to do. */
3345 if (bb
->aux
== e_fall
->dest
)
3348 /* A fallthru to exit block. */
3349 if (e_fall
->dest
== EXIT_BLOCK_PTR
)
3353 /* We got here if we need to add a new jump insn.
3354 Note force_nonfallthru can delete E_FALL and thus we have to
3355 save E_FALL->src prior to the call to force_nonfallthru. */
3356 src_bb
= e_fall
->src
;
3357 nb
= force_nonfallthru_and_redirect (e_fall
, e_fall
->dest
, ret_label
);
3362 /* Don't process this new block. */
3365 /* Make sure new bb is tagged for correct section (same as
3366 fall-thru source, since you cannot fall-thru across
3367 section boundaries). */
3368 BB_COPY_PARTITION (src_bb
, single_pred (bb
));
3369 if (flag_reorder_blocks_and_partition
3370 && targetm_common
.have_named_sections
3371 && JUMP_P (BB_END (bb
))
3372 && !any_condjump_p (BB_END (bb
))
3373 && (EDGE_SUCC (bb
, 0)->flags
& EDGE_CROSSING
))
3374 add_reg_note (BB_END (bb
), REG_CROSSING_JUMP
, NULL_RTX
);
3378 relink_block_chain (/*stay_in_cfglayout_mode=*/false);
3380 /* Annoying special case - jump around dead jumptables left in the code. */
3383 edge e
= find_fallthru_edge (bb
->succs
);
3385 if (e
&& !can_fallthru (e
->src
, e
->dest
))
3386 force_nonfallthru (e
);
3389 /* Ensure goto_locus from edges has some instructions with that locus
3397 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
3398 if (LOCATION_LOCUS (e
->goto_locus
) != UNKNOWN_LOCATION
3399 && !(e
->flags
& EDGE_ABNORMAL
))
3403 basic_block dest
, nb
;
3406 insn
= BB_END (e
->src
);
3407 end
= PREV_INSN (BB_HEAD (e
->src
));
3409 && (!NONDEBUG_INSN_P (insn
) || !INSN_HAS_LOCATION (insn
)))
3410 insn
= PREV_INSN (insn
);
3412 && INSN_LOCATION (insn
) == e
->goto_locus
)
3414 if (simplejump_p (BB_END (e
->src
))
3415 && !INSN_HAS_LOCATION (BB_END (e
->src
)))
3417 INSN_LOCATION (BB_END (e
->src
)) = e
->goto_locus
;
3421 if (dest
== EXIT_BLOCK_PTR
)
3423 /* Non-fallthru edges to the exit block cannot be split. */
3424 if (!(e
->flags
& EDGE_FALLTHRU
))
3429 insn
= BB_HEAD (dest
);
3430 end
= NEXT_INSN (BB_END (dest
));
3431 while (insn
!= end
&& !NONDEBUG_INSN_P (insn
))
3432 insn
= NEXT_INSN (insn
);
3433 if (insn
!= end
&& INSN_HAS_LOCATION (insn
)
3434 && INSN_LOCATION (insn
) == e
->goto_locus
)
3437 nb
= split_edge (e
);
3438 if (!INSN_P (BB_END (nb
)))
3439 BB_END (nb
) = emit_insn_after_noloc (gen_nop (), BB_END (nb
),
3441 INSN_LOCATION (BB_END (nb
)) = e
->goto_locus
;
3443 /* If there are other incoming edges to the destination block
3444 with the same goto locus, redirect them to the new block as
3445 well, this can prevent other such blocks from being created
3446 in subsequent iterations of the loop. */
3447 for (ei2
= ei_start (dest
->preds
); (e2
= ei_safe_edge (ei2
)); )
3448 if (LOCATION_LOCUS (e2
->goto_locus
) != UNKNOWN_LOCATION
3449 && !(e2
->flags
& (EDGE_ABNORMAL
| EDGE_FALLTHRU
))
3450 && e
->goto_locus
== e2
->goto_locus
)
3451 redirect_edge_and_branch (e2
, nb
);
3458 /* Perform sanity checks on the insn chain.
3459 1. Check that next/prev pointers are consistent in both the forward and
3461 2. Count insns in chain, going both directions, and check if equal.
3462 3. Check that get_last_insn () returns the actual end of chain. */
3465 verify_insn_chain (void)
3467 rtx x
, prevx
, nextx
;
3468 int insn_cnt1
, insn_cnt2
;
3470 for (prevx
= NULL
, insn_cnt1
= 1, x
= get_insns ();
3472 prevx
= x
, insn_cnt1
++, x
= NEXT_INSN (x
))
3473 gcc_assert (PREV_INSN (x
) == prevx
);
3475 gcc_assert (prevx
== get_last_insn ());
3477 for (nextx
= NULL
, insn_cnt2
= 1, x
= get_last_insn ();
3479 nextx
= x
, insn_cnt2
++, x
= PREV_INSN (x
))
3480 gcc_assert (NEXT_INSN (x
) == nextx
);
3482 gcc_assert (insn_cnt1
== insn_cnt2
);
3485 /* If we have assembler epilogues, the block falling through to exit must
3486 be the last one in the reordered chain when we reach final. Ensure
3487 that this condition is met. */
3489 fixup_fallthru_exit_predecessor (void)
3492 basic_block bb
= NULL
;
3494 /* This transformation is not valid before reload, because we might
3495 separate a call from the instruction that copies the return
3497 gcc_assert (reload_completed
);
3499 e
= find_fallthru_edge (EXIT_BLOCK_PTR
->preds
);
3505 basic_block c
= ENTRY_BLOCK_PTR
->next_bb
;
3507 /* If the very first block is the one with the fall-through exit
3508 edge, we have to split that block. */
3511 bb
= split_block (bb
, NULL
)->dest
;
3514 BB_FOOTER (bb
) = BB_FOOTER (c
);
3515 BB_FOOTER (c
) = NULL
;
3518 while (c
->aux
!= bb
)
3519 c
= (basic_block
) c
->aux
;
3523 c
= (basic_block
) c
->aux
;
3530 /* In case there are more than one fallthru predecessors of exit, force that
3531 there is only one. */
3534 force_one_exit_fallthru (void)
3536 edge e
, predecessor
= NULL
;
3539 basic_block forwarder
, bb
;
3541 FOR_EACH_EDGE (e
, ei
, EXIT_BLOCK_PTR
->preds
)
3542 if (e
->flags
& EDGE_FALLTHRU
)
3544 if (predecessor
== NULL
)
3556 /* Exit has several fallthru predecessors. Create a forwarder block for
3558 forwarder
= split_edge (predecessor
);
3559 for (ei
= ei_start (EXIT_BLOCK_PTR
->preds
); (e
= ei_safe_edge (ei
)); )
3561 if (e
->src
== forwarder
3562 || !(e
->flags
& EDGE_FALLTHRU
))
3565 redirect_edge_and_branch_force (e
, forwarder
);
3568 /* Fix up the chain of blocks -- make FORWARDER immediately precede the
3572 if (bb
->aux
== NULL
&& bb
!= forwarder
)
3574 bb
->aux
= forwarder
;
3580 /* Return true in case it is possible to duplicate the basic block BB. */
3583 cfg_layout_can_duplicate_bb_p (const_basic_block bb
)
3585 /* Do not attempt to duplicate tablejumps, as we need to unshare
3586 the dispatch table. This is difficult to do, as the instructions
3587 computing jump destination may be hoisted outside the basic block. */
3588 if (tablejump_p (BB_END (bb
), NULL
, NULL
))
3591 /* Do not duplicate blocks containing insns that can't be copied. */
3592 if (targetm
.cannot_copy_insn_p
)
3594 rtx insn
= BB_HEAD (bb
);
3597 if (INSN_P (insn
) && targetm
.cannot_copy_insn_p (insn
))
3599 if (insn
== BB_END (bb
))
3601 insn
= NEXT_INSN (insn
);
3609 duplicate_insn_chain (rtx from
, rtx to
)
3611 rtx insn
, next
, last
, copy
;
3613 /* Avoid updating of boundaries of previous basic block. The
3614 note will get removed from insn stream in fixup. */
3615 last
= emit_note (NOTE_INSN_DELETED
);
3617 /* Create copy at the end of INSN chain. The chain will
3618 be reordered later. */
3619 for (insn
= from
; insn
!= NEXT_INSN (to
); insn
= NEXT_INSN (insn
))
3621 switch (GET_CODE (insn
))
3624 /* Don't duplicate label debug insns. */
3625 if (TREE_CODE (INSN_VAR_LOCATION_DECL (insn
)) == LABEL_DECL
)
3631 copy
= emit_copy_of_insn_after (insn
, get_last_insn ());
3632 if (JUMP_P (insn
) && JUMP_LABEL (insn
) != NULL_RTX
3633 && ANY_RETURN_P (JUMP_LABEL (insn
)))
3634 JUMP_LABEL (copy
) = JUMP_LABEL (insn
);
3635 maybe_copy_prologue_epilogue_insn (insn
, copy
);
3638 case JUMP_TABLE_DATA
:
3639 /* Avoid copying of dispatch tables. We never duplicate
3640 tablejumps, so this can hit only in case the table got
3641 moved far from original jump.
3642 Avoid copying following barrier as well if any
3643 (and debug insns in between). */
3644 for (next
= NEXT_INSN (insn
);
3645 next
!= NEXT_INSN (to
);
3646 next
= NEXT_INSN (next
))
3647 if (!DEBUG_INSN_P (next
))
3649 if (next
!= NEXT_INSN (to
) && BARRIER_P (next
))
3661 switch (NOTE_KIND (insn
))
3663 /* In case prologue is empty and function contain label
3664 in first BB, we may want to copy the block. */
3665 case NOTE_INSN_PROLOGUE_END
:
3667 case NOTE_INSN_DELETED
:
3668 case NOTE_INSN_DELETED_LABEL
:
3669 case NOTE_INSN_DELETED_DEBUG_LABEL
:
3670 /* No problem to strip these. */
3671 case NOTE_INSN_FUNCTION_BEG
:
3672 /* There is always just single entry to function. */
3673 case NOTE_INSN_BASIC_BLOCK
:
3676 case NOTE_INSN_EPILOGUE_BEG
:
3677 case NOTE_INSN_SWITCH_TEXT_SECTIONS
:
3678 emit_note_copy (insn
);
3682 /* All other notes should have already been eliminated. */
3690 insn
= NEXT_INSN (last
);
3695 /* Create a duplicate of the basic block BB. */
3698 cfg_layout_duplicate_bb (basic_block bb
)
3703 insn
= duplicate_insn_chain (BB_HEAD (bb
), BB_END (bb
));
3704 new_bb
= create_basic_block (insn
,
3705 insn
? get_last_insn () : NULL
,
3706 EXIT_BLOCK_PTR
->prev_bb
);
3708 BB_COPY_PARTITION (new_bb
, bb
);
3711 insn
= BB_HEADER (bb
);
3712 while (NEXT_INSN (insn
))
3713 insn
= NEXT_INSN (insn
);
3714 insn
= duplicate_insn_chain (BB_HEADER (bb
), insn
);
3716 BB_HEADER (new_bb
) = unlink_insn_chain (insn
, get_last_insn ());
3721 insn
= BB_FOOTER (bb
);
3722 while (NEXT_INSN (insn
))
3723 insn
= NEXT_INSN (insn
);
3724 insn
= duplicate_insn_chain (BB_FOOTER (bb
), insn
);
3726 BB_FOOTER (new_bb
) = unlink_insn_chain (insn
, get_last_insn ());
3733 /* Main entry point to this module - initialize the datastructures for
3734 CFG layout changes. It keeps LOOPS up-to-date if not null.
3736 FLAGS is a set of additional flags to pass to cleanup_cfg(). */
3739 cfg_layout_initialize (unsigned int flags
)
3744 initialize_original_copy_tables ();
3746 cfg_layout_rtl_register_cfg_hooks ();
3748 record_effective_endpoints ();
3750 /* Make sure that the targets of non local gotos are marked. */
3751 for (x
= nonlocal_goto_handler_labels
; x
; x
= XEXP (x
, 1))
3753 bb
= BLOCK_FOR_INSN (XEXP (x
, 0));
3754 bb
->flags
|= BB_NON_LOCAL_GOTO_TARGET
;
3757 cleanup_cfg (CLEANUP_CFGLAYOUT
| flags
);
3760 /* Splits superblocks. */
3762 break_superblocks (void)
3764 sbitmap superblocks
;
3768 superblocks
= sbitmap_alloc (last_basic_block
);
3769 bitmap_clear (superblocks
);
3772 if (bb
->flags
& BB_SUPERBLOCK
)
3774 bb
->flags
&= ~BB_SUPERBLOCK
;
3775 bitmap_set_bit (superblocks
, bb
->index
);
3781 rebuild_jump_labels (get_insns ());
3782 find_many_sub_basic_blocks (superblocks
);
3788 /* Finalize the changes: reorder insn list according to the sequence specified
3789 by aux pointers, enter compensation code, rebuild scope forest. */
3792 cfg_layout_finalize (void)
3794 #ifdef ENABLE_CHECKING
3795 verify_flow_info ();
3797 force_one_exit_fallthru ();
3798 rtl_register_cfg_hooks ();
3799 if (reload_completed
3800 #ifdef HAVE_epilogue
3804 fixup_fallthru_exit_predecessor ();
3805 fixup_reorder_chain ();
3807 rebuild_jump_labels (get_insns ());
3808 delete_dead_jumptables ();
3810 #ifdef ENABLE_CHECKING
3811 verify_insn_chain ();
3812 verify_flow_info ();
3817 /* Same as split_block but update cfg_layout structures. */
3820 cfg_layout_split_block (basic_block bb
, void *insnp
)
3822 rtx insn
= (rtx
) insnp
;
3823 basic_block new_bb
= rtl_split_block (bb
, insn
);
3825 BB_FOOTER (new_bb
) = BB_FOOTER (bb
);
3826 BB_FOOTER (bb
) = NULL
;
3831 /* Redirect Edge to DEST. */
3833 cfg_layout_redirect_edge_and_branch (edge e
, basic_block dest
)
3835 basic_block src
= e
->src
;
3838 if (e
->flags
& (EDGE_ABNORMAL_CALL
| EDGE_EH
))
3841 if (e
->dest
== dest
)
3844 if (e
->src
!= ENTRY_BLOCK_PTR
3845 && (ret
= try_redirect_by_replacing_jump (e
, dest
, true)))
3847 df_set_bb_dirty (src
);
3851 if (e
->src
== ENTRY_BLOCK_PTR
3852 && (e
->flags
& EDGE_FALLTHRU
) && !(e
->flags
& EDGE_COMPLEX
))
3855 fprintf (dump_file
, "Redirecting entry edge from bb %i to %i\n",
3856 e
->src
->index
, dest
->index
);
3858 df_set_bb_dirty (e
->src
);
3859 redirect_edge_succ (e
, dest
);
3863 /* Redirect_edge_and_branch may decide to turn branch into fallthru edge
3864 in the case the basic block appears to be in sequence. Avoid this
3867 if (e
->flags
& EDGE_FALLTHRU
)
3869 /* Redirect any branch edges unified with the fallthru one. */
3870 if (JUMP_P (BB_END (src
))
3871 && label_is_jump_target_p (BB_HEAD (e
->dest
),
3877 fprintf (dump_file
, "Fallthru edge unified with branch "
3878 "%i->%i redirected to %i\n",
3879 e
->src
->index
, e
->dest
->index
, dest
->index
);
3880 e
->flags
&= ~EDGE_FALLTHRU
;
3881 redirected
= redirect_branch_edge (e
, dest
);
3882 gcc_assert (redirected
);
3883 redirected
->flags
|= EDGE_FALLTHRU
;
3884 df_set_bb_dirty (redirected
->src
);
3887 /* In case we are redirecting fallthru edge to the branch edge
3888 of conditional jump, remove it. */
3889 if (EDGE_COUNT (src
->succs
) == 2)
3891 /* Find the edge that is different from E. */
3892 edge s
= EDGE_SUCC (src
, EDGE_SUCC (src
, 0) == e
);
3895 && any_condjump_p (BB_END (src
))
3896 && onlyjump_p (BB_END (src
)))
3897 delete_insn (BB_END (src
));
3900 fprintf (dump_file
, "Redirecting fallthru edge %i->%i to %i\n",
3901 e
->src
->index
, e
->dest
->index
, dest
->index
);
3902 ret
= redirect_edge_succ_nodup (e
, dest
);
3905 ret
= redirect_branch_edge (e
, dest
);
3907 /* We don't want simplejumps in the insn stream during cfglayout. */
3908 gcc_assert (!simplejump_p (BB_END (src
)));
3910 df_set_bb_dirty (src
);
3914 /* Simple wrapper as we always can redirect fallthru edges. */
3916 cfg_layout_redirect_edge_and_branch_force (edge e
, basic_block dest
)
3918 edge redirected
= cfg_layout_redirect_edge_and_branch (e
, dest
);
3920 gcc_assert (redirected
);
3924 /* Same as delete_basic_block but update cfg_layout structures. */
3927 cfg_layout_delete_block (basic_block bb
)
3929 rtx insn
, next
, prev
= PREV_INSN (BB_HEAD (bb
)), *to
, remaints
;
3933 next
= BB_HEAD (bb
);
3935 NEXT_INSN (prev
) = BB_HEADER (bb
);
3937 set_first_insn (BB_HEADER (bb
));
3938 PREV_INSN (BB_HEADER (bb
)) = prev
;
3939 insn
= BB_HEADER (bb
);
3940 while (NEXT_INSN (insn
))
3941 insn
= NEXT_INSN (insn
);
3942 NEXT_INSN (insn
) = next
;
3943 PREV_INSN (next
) = insn
;
3945 next
= NEXT_INSN (BB_END (bb
));
3948 insn
= BB_FOOTER (bb
);
3951 if (BARRIER_P (insn
))
3953 if (PREV_INSN (insn
))
3954 NEXT_INSN (PREV_INSN (insn
)) = NEXT_INSN (insn
);
3956 BB_FOOTER (bb
) = NEXT_INSN (insn
);
3957 if (NEXT_INSN (insn
))
3958 PREV_INSN (NEXT_INSN (insn
)) = PREV_INSN (insn
);
3962 insn
= NEXT_INSN (insn
);
3967 NEXT_INSN (insn
) = BB_FOOTER (bb
);
3968 PREV_INSN (BB_FOOTER (bb
)) = insn
;
3969 while (NEXT_INSN (insn
))
3970 insn
= NEXT_INSN (insn
);
3971 NEXT_INSN (insn
) = next
;
3973 PREV_INSN (next
) = insn
;
3975 set_last_insn (insn
);
3978 if (bb
->next_bb
!= EXIT_BLOCK_PTR
)
3979 to
= &BB_HEADER (bb
->next_bb
);
3981 to
= &cfg_layout_function_footer
;
3983 rtl_delete_block (bb
);
3986 prev
= NEXT_INSN (prev
);
3988 prev
= get_insns ();
3990 next
= PREV_INSN (next
);
3992 next
= get_last_insn ();
3994 if (next
&& NEXT_INSN (next
) != prev
)
3996 remaints
= unlink_insn_chain (prev
, next
);
3998 while (NEXT_INSN (insn
))
3999 insn
= NEXT_INSN (insn
);
4000 NEXT_INSN (insn
) = *to
;
4002 PREV_INSN (*to
) = insn
;
4007 /* Return true when blocks A and B can be safely merged. */
4010 cfg_layout_can_merge_blocks_p (basic_block a
, basic_block b
)
4012 /* If we are partitioning hot/cold basic blocks, we don't want to
4013 mess up unconditional or indirect jumps that cross between hot
4016 Basic block partitioning may result in some jumps that appear to
4017 be optimizable (or blocks that appear to be mergeable), but which really
4018 must be left untouched (they are required to make it safely across
4019 partition boundaries). See the comments at the top of
4020 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
4022 if (BB_PARTITION (a
) != BB_PARTITION (b
))
4025 /* Protect the loop latches. */
4026 if (current_loops
&& b
->loop_father
->latch
== b
)
4029 /* If we would end up moving B's instructions, make sure it doesn't fall
4030 through into the exit block, since we cannot recover from a fallthrough
4031 edge into the exit block occurring in the middle of a function. */
4032 if (NEXT_INSN (BB_END (a
)) != BB_HEAD (b
))
4034 edge e
= find_fallthru_edge (b
->succs
);
4035 if (e
&& e
->dest
== EXIT_BLOCK_PTR
)
4039 /* There must be exactly one edge in between the blocks. */
4040 return (single_succ_p (a
)
4041 && single_succ (a
) == b
4042 && single_pred_p (b
) == 1
4044 /* Must be simple edge. */
4045 && !(single_succ_edge (a
)->flags
& EDGE_COMPLEX
)
4046 && a
!= ENTRY_BLOCK_PTR
&& b
!= EXIT_BLOCK_PTR
4047 /* If the jump insn has side effects, we can't kill the edge.
4048 When not optimizing, try_redirect_by_replacing_jump will
4049 not allow us to redirect an edge by replacing a table jump. */
4050 && (!JUMP_P (BB_END (a
))
4051 || ((!optimize
|| reload_completed
)
4052 ? simplejump_p (BB_END (a
)) : onlyjump_p (BB_END (a
)))));
4055 /* Merge block A and B. The blocks must be mergeable. */
4058 cfg_layout_merge_blocks (basic_block a
, basic_block b
)
4060 bool forwarder_p
= (b
->flags
& BB_FORWARDER_BLOCK
) != 0;
4063 gcc_checking_assert (cfg_layout_can_merge_blocks_p (a
, b
));
4066 fprintf (dump_file
, "Merging block %d into block %d...\n", b
->index
,
4069 /* If there was a CODE_LABEL beginning B, delete it. */
4070 if (LABEL_P (BB_HEAD (b
)))
4072 delete_insn (BB_HEAD (b
));
4075 /* We should have fallthru edge in a, or we can do dummy redirection to get
4077 if (JUMP_P (BB_END (a
)))
4078 try_redirect_by_replacing_jump (EDGE_SUCC (a
, 0), b
, true);
4079 gcc_assert (!JUMP_P (BB_END (a
)));
4081 /* When not optimizing CFG and the edge is the only place in RTL which holds
4082 some unique locus, emit a nop with that locus in between. */
4084 emit_nop_for_unique_locus_between (a
, b
);
4086 /* Move things from b->footer after a->footer. */
4090 BB_FOOTER (a
) = BB_FOOTER (b
);
4093 rtx last
= BB_FOOTER (a
);
4095 while (NEXT_INSN (last
))
4096 last
= NEXT_INSN (last
);
4097 NEXT_INSN (last
) = BB_FOOTER (b
);
4098 PREV_INSN (BB_FOOTER (b
)) = last
;
4100 BB_FOOTER (b
) = NULL
;
4103 /* Move things from b->header before a->footer.
4104 Note that this may include dead tablejump data, but we don't clean
4105 those up until we go out of cfglayout mode. */
4108 if (! BB_FOOTER (a
))
4109 BB_FOOTER (a
) = BB_HEADER (b
);
4112 rtx last
= BB_HEADER (b
);
4114 while (NEXT_INSN (last
))
4115 last
= NEXT_INSN (last
);
4116 NEXT_INSN (last
) = BB_FOOTER (a
);
4117 PREV_INSN (BB_FOOTER (a
)) = last
;
4118 BB_FOOTER (a
) = BB_HEADER (b
);
4120 BB_HEADER (b
) = NULL
;
4123 /* In the case basic blocks are not adjacent, move them around. */
4124 if (NEXT_INSN (BB_END (a
)) != BB_HEAD (b
))
4126 insn
= unlink_insn_chain (BB_HEAD (b
), BB_END (b
));
4128 emit_insn_after_noloc (insn
, BB_END (a
), a
);
4130 /* Otherwise just re-associate the instructions. */
4134 BB_END (a
) = BB_END (b
);
4137 /* emit_insn_after_noloc doesn't call df_insn_change_bb.
4138 We need to explicitly call. */
4139 update_bb_for_insn_chain (insn
, BB_END (b
), a
);
4141 /* Skip possible DELETED_LABEL insn. */
4142 if (!NOTE_INSN_BASIC_BLOCK_P (insn
))
4143 insn
= NEXT_INSN (insn
);
4144 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (insn
));
4145 BB_HEAD (b
) = BB_END (b
) = NULL
;
4148 df_bb_delete (b
->index
);
4150 /* If B was a forwarder block, propagate the locus on the edge. */
4152 && LOCATION_LOCUS (EDGE_SUCC (b
, 0)->goto_locus
) == UNKNOWN_LOCATION
)
4153 EDGE_SUCC (b
, 0)->goto_locus
= EDGE_SUCC (a
, 0)->goto_locus
;
4156 fprintf (dump_file
, "Merged blocks %d and %d.\n", a
->index
, b
->index
);
4162 cfg_layout_split_edge (edge e
)
4164 basic_block new_bb
=
4165 create_basic_block (e
->src
!= ENTRY_BLOCK_PTR
4166 ? NEXT_INSN (BB_END (e
->src
)) : get_insns (),
4169 if (e
->dest
== EXIT_BLOCK_PTR
)
4170 BB_COPY_PARTITION (new_bb
, e
->src
);
4172 BB_COPY_PARTITION (new_bb
, e
->dest
);
4173 make_edge (new_bb
, e
->dest
, EDGE_FALLTHRU
);
4174 redirect_edge_and_branch_force (e
, new_bb
);
4179 /* Do postprocessing after making a forwarder block joined by edge FALLTHRU. */
4182 rtl_make_forwarder_block (edge fallthru ATTRIBUTE_UNUSED
)
4186 /* Return true if BB contains only labels or non-executable
4190 rtl_block_empty_p (basic_block bb
)
4194 if (bb
== ENTRY_BLOCK_PTR
|| bb
== EXIT_BLOCK_PTR
)
4197 FOR_BB_INSNS (bb
, insn
)
4198 if (NONDEBUG_INSN_P (insn
) && !any_uncondjump_p (insn
))
4204 /* Split a basic block if it ends with a conditional branch and if
4205 the other part of the block is not empty. */
4208 rtl_split_block_before_cond_jump (basic_block bb
)
4211 rtx split_point
= NULL
;
4213 bool found_code
= false;
4215 FOR_BB_INSNS (bb
, insn
)
4217 if (any_condjump_p (insn
))
4219 else if (NONDEBUG_INSN_P (insn
))
4224 /* Did not find everything. */
4225 if (found_code
&& split_point
)
4226 return split_block (bb
, split_point
)->dest
;
4231 /* Return 1 if BB ends with a call, possibly followed by some
4232 instructions that must stay with the call, 0 otherwise. */
4235 rtl_block_ends_with_call_p (basic_block bb
)
4237 rtx insn
= BB_END (bb
);
4239 while (!CALL_P (insn
)
4240 && insn
!= BB_HEAD (bb
)
4241 && (keep_with_call_p (insn
)
4243 || DEBUG_INSN_P (insn
)))
4244 insn
= PREV_INSN (insn
);
4245 return (CALL_P (insn
));
4248 /* Return 1 if BB ends with a conditional branch, 0 otherwise. */
4251 rtl_block_ends_with_condjump_p (const_basic_block bb
)
4253 return any_condjump_p (BB_END (bb
));
4256 /* Return true if we need to add fake edge to exit.
4257 Helper function for rtl_flow_call_edges_add. */
4260 need_fake_edge_p (const_rtx insn
)
4266 && !SIBLING_CALL_P (insn
)
4267 && !find_reg_note (insn
, REG_NORETURN
, NULL
)
4268 && !(RTL_CONST_OR_PURE_CALL_P (insn
))))
4271 return ((GET_CODE (PATTERN (insn
)) == ASM_OPERANDS
4272 && MEM_VOLATILE_P (PATTERN (insn
)))
4273 || (GET_CODE (PATTERN (insn
)) == PARALLEL
4274 && asm_noperands (insn
) != -1
4275 && MEM_VOLATILE_P (XVECEXP (PATTERN (insn
), 0, 0)))
4276 || GET_CODE (PATTERN (insn
)) == ASM_INPUT
);
4279 /* Add fake edges to the function exit for any non constant and non noreturn
4280 calls, volatile inline assembly in the bitmap of blocks specified by
4281 BLOCKS or to the whole CFG if BLOCKS is zero. Return the number of blocks
4284 The goal is to expose cases in which entering a basic block does not imply
4285 that all subsequent instructions must be executed. */
4288 rtl_flow_call_edges_add (sbitmap blocks
)
4291 int blocks_split
= 0;
4292 int last_bb
= last_basic_block
;
4293 bool check_last_block
= false;
4295 if (n_basic_blocks
== NUM_FIXED_BLOCKS
)
4299 check_last_block
= true;
4301 check_last_block
= bitmap_bit_p (blocks
, EXIT_BLOCK_PTR
->prev_bb
->index
);
4303 /* In the last basic block, before epilogue generation, there will be
4304 a fallthru edge to EXIT. Special care is required if the last insn
4305 of the last basic block is a call because make_edge folds duplicate
4306 edges, which would result in the fallthru edge also being marked
4307 fake, which would result in the fallthru edge being removed by
4308 remove_fake_edges, which would result in an invalid CFG.
4310 Moreover, we can't elide the outgoing fake edge, since the block
4311 profiler needs to take this into account in order to solve the minimal
4312 spanning tree in the case that the call doesn't return.
4314 Handle this by adding a dummy instruction in a new last basic block. */
4315 if (check_last_block
)
4317 basic_block bb
= EXIT_BLOCK_PTR
->prev_bb
;
4318 rtx insn
= BB_END (bb
);
4320 /* Back up past insns that must be kept in the same block as a call. */
4321 while (insn
!= BB_HEAD (bb
)
4322 && keep_with_call_p (insn
))
4323 insn
= PREV_INSN (insn
);
4325 if (need_fake_edge_p (insn
))
4329 e
= find_edge (bb
, EXIT_BLOCK_PTR
);
4332 insert_insn_on_edge (gen_use (const0_rtx
), e
);
4333 commit_edge_insertions ();
4338 /* Now add fake edges to the function exit for any non constant
4339 calls since there is no way that we can determine if they will
4342 for (i
= NUM_FIXED_BLOCKS
; i
< last_bb
; i
++)
4344 basic_block bb
= BASIC_BLOCK (i
);
4351 if (blocks
&& !bitmap_bit_p (blocks
, i
))
4354 for (insn
= BB_END (bb
); ; insn
= prev_insn
)
4356 prev_insn
= PREV_INSN (insn
);
4357 if (need_fake_edge_p (insn
))
4360 rtx split_at_insn
= insn
;
4362 /* Don't split the block between a call and an insn that should
4363 remain in the same block as the call. */
4365 while (split_at_insn
!= BB_END (bb
)
4366 && keep_with_call_p (NEXT_INSN (split_at_insn
)))
4367 split_at_insn
= NEXT_INSN (split_at_insn
);
4369 /* The handling above of the final block before the epilogue
4370 should be enough to verify that there is no edge to the exit
4371 block in CFG already. Calling make_edge in such case would
4372 cause us to mark that edge as fake and remove it later. */
4374 #ifdef ENABLE_CHECKING
4375 if (split_at_insn
== BB_END (bb
))
4377 e
= find_edge (bb
, EXIT_BLOCK_PTR
);
4378 gcc_assert (e
== NULL
);
4382 /* Note that the following may create a new basic block
4383 and renumber the existing basic blocks. */
4384 if (split_at_insn
!= BB_END (bb
))
4386 e
= split_block (bb
, split_at_insn
);
4391 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
4394 if (insn
== BB_HEAD (bb
))
4400 verify_flow_info ();
4402 return blocks_split
;
4405 /* Add COMP_RTX as a condition at end of COND_BB. FIRST_HEAD is
4406 the conditional branch target, SECOND_HEAD should be the fall-thru
4407 there is no need to handle this here the loop versioning code handles
4408 this. the reason for SECON_HEAD is that it is needed for condition
4409 in trees, and this should be of the same type since it is a hook. */
4411 rtl_lv_add_condition_to_bb (basic_block first_head
,
4412 basic_block second_head ATTRIBUTE_UNUSED
,
4413 basic_block cond_bb
, void *comp_rtx
)
4415 rtx label
, seq
, jump
;
4416 rtx op0
= XEXP ((rtx
)comp_rtx
, 0);
4417 rtx op1
= XEXP ((rtx
)comp_rtx
, 1);
4418 enum rtx_code comp
= GET_CODE ((rtx
)comp_rtx
);
4419 enum machine_mode mode
;
4422 label
= block_label (first_head
);
4423 mode
= GET_MODE (op0
);
4424 if (mode
== VOIDmode
)
4425 mode
= GET_MODE (op1
);
4428 op0
= force_operand (op0
, NULL_RTX
);
4429 op1
= force_operand (op1
, NULL_RTX
);
4430 do_compare_rtx_and_jump (op0
, op1
, comp
, 0,
4431 mode
, NULL_RTX
, NULL_RTX
, label
, -1);
4432 jump
= get_last_insn ();
4433 JUMP_LABEL (jump
) = label
;
4434 LABEL_NUSES (label
)++;
4438 /* Add the new cond , in the new head. */
4439 emit_insn_after(seq
, BB_END(cond_bb
));
4443 /* Given a block B with unconditional branch at its end, get the
4444 store the return the branch edge and the fall-thru edge in
4445 BRANCH_EDGE and FALLTHRU_EDGE respectively. */
4447 rtl_extract_cond_bb_edges (basic_block b
, edge
*branch_edge
,
4448 edge
*fallthru_edge
)
4450 edge e
= EDGE_SUCC (b
, 0);
4452 if (e
->flags
& EDGE_FALLTHRU
)
4455 *branch_edge
= EDGE_SUCC (b
, 1);
4460 *fallthru_edge
= EDGE_SUCC (b
, 1);
4465 init_rtl_bb_info (basic_block bb
)
4467 gcc_assert (!bb
->il
.x
.rtl
);
4468 bb
->il
.x
.head_
= NULL
;
4469 bb
->il
.x
.rtl
= ggc_alloc_cleared_rtl_bb_info ();
4472 /* Returns true if it is possible to remove edge E by redirecting
4473 it to the destination of the other edge from E->src. */
4476 rtl_can_remove_branch_p (const_edge e
)
4478 const_basic_block src
= e
->src
;
4479 const_basic_block target
= EDGE_SUCC (src
, EDGE_SUCC (src
, 0) == e
)->dest
;
4480 const_rtx insn
= BB_END (src
), set
;
4482 /* The conditions are taken from try_redirect_by_replacing_jump. */
4483 if (target
== EXIT_BLOCK_PTR
)
4486 if (e
->flags
& (EDGE_ABNORMAL_CALL
| EDGE_EH
))
4489 if (find_reg_note (insn
, REG_CROSSING_JUMP
, NULL_RTX
)
4490 || BB_PARTITION (src
) != BB_PARTITION (target
))
4493 if (!onlyjump_p (insn
)
4494 || tablejump_p (insn
, NULL
, NULL
))
4497 set
= single_set (insn
);
4498 if (!set
|| side_effects_p (set
))
4505 rtl_duplicate_bb (basic_block bb
)
4507 bb
= cfg_layout_duplicate_bb (bb
);
4512 /* Do book-keeping of basic block BB for the profile consistency checker.
4513 If AFTER_PASS is 0, do pre-pass accounting, or if AFTER_PASS is 1
4514 then do post-pass accounting. Store the counting in RECORD. */
4516 rtl_account_profile_record (basic_block bb
, int after_pass
,
4517 struct profile_record
*record
)
4520 FOR_BB_INSNS (bb
, insn
)
4523 record
->size
[after_pass
]
4524 += insn_rtx_cost (PATTERN (insn
), false);
4525 if (profile_status
== PROFILE_READ
)
4526 record
->time
[after_pass
]
4527 += insn_rtx_cost (PATTERN (insn
), true) * bb
->count
;
4528 else if (profile_status
== PROFILE_GUESSED
)
4529 record
->time
[after_pass
]
4530 += insn_rtx_cost (PATTERN (insn
), true) * bb
->frequency
;
4534 /* Implementation of CFG manipulation for linearized RTL. */
4535 struct cfg_hooks rtl_cfg_hooks
= {
4537 rtl_verify_flow_info
,
4539 rtl_dump_bb_for_graph
,
4540 rtl_create_basic_block
,
4541 rtl_redirect_edge_and_branch
,
4542 rtl_redirect_edge_and_branch_force
,
4543 rtl_can_remove_branch_p
,
4546 rtl_move_block_after
,
4547 rtl_can_merge_blocks
, /* can_merge_blocks_p */
4551 cfg_layout_can_duplicate_bb_p
,
4554 rtl_make_forwarder_block
,
4555 rtl_tidy_fallthru_edge
,
4556 rtl_force_nonfallthru
,
4557 rtl_block_ends_with_call_p
,
4558 rtl_block_ends_with_condjump_p
,
4559 rtl_flow_call_edges_add
,
4560 NULL
, /* execute_on_growing_pred */
4561 NULL
, /* execute_on_shrinking_pred */
4562 NULL
, /* duplicate loop for trees */
4563 NULL
, /* lv_add_condition_to_bb */
4564 NULL
, /* lv_adjust_loop_header_phi*/
4565 NULL
, /* extract_cond_bb_edges */
4566 NULL
, /* flush_pending_stmts */
4567 rtl_block_empty_p
, /* block_empty_p */
4568 rtl_split_block_before_cond_jump
, /* split_block_before_cond_jump */
4569 rtl_account_profile_record
,
4572 /* Implementation of CFG manipulation for cfg layout RTL, where
4573 basic block connected via fallthru edges does not have to be adjacent.
4574 This representation will hopefully become the default one in future
4575 version of the compiler. */
4577 struct cfg_hooks cfg_layout_rtl_cfg_hooks
= {
4579 rtl_verify_flow_info_1
,
4581 rtl_dump_bb_for_graph
,
4582 cfg_layout_create_basic_block
,
4583 cfg_layout_redirect_edge_and_branch
,
4584 cfg_layout_redirect_edge_and_branch_force
,
4585 rtl_can_remove_branch_p
,
4586 cfg_layout_delete_block
,
4587 cfg_layout_split_block
,
4588 rtl_move_block_after
,
4589 cfg_layout_can_merge_blocks_p
,
4590 cfg_layout_merge_blocks
,
4593 cfg_layout_can_duplicate_bb_p
,
4594 cfg_layout_duplicate_bb
,
4595 cfg_layout_split_edge
,
4596 rtl_make_forwarder_block
,
4597 NULL
, /* tidy_fallthru_edge */
4598 rtl_force_nonfallthru
,
4599 rtl_block_ends_with_call_p
,
4600 rtl_block_ends_with_condjump_p
,
4601 rtl_flow_call_edges_add
,
4602 NULL
, /* execute_on_growing_pred */
4603 NULL
, /* execute_on_shrinking_pred */
4604 duplicate_loop_to_header_edge
, /* duplicate loop for trees */
4605 rtl_lv_add_condition_to_bb
, /* lv_add_condition_to_bb */
4606 NULL
, /* lv_adjust_loop_header_phi*/
4607 rtl_extract_cond_bb_edges
, /* extract_cond_bb_edges */
4608 NULL
, /* flush_pending_stmts */
4609 rtl_block_empty_p
, /* block_empty_p */
4610 rtl_split_block_before_cond_jump
, /* split_block_before_cond_jump */
4611 rtl_account_profile_record
,
4614 #include "gt-cfgrtl.h"