1 /* Control flow graph manipulation code for GNU compiler.
2 Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
3 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010,
4 2011, 2012 Free Software Foundation, Inc.
5
6 This file is part of GCC.
7
8 GCC is free software; you can redistribute it and/or modify it under
9 the terms of the GNU General Public License as published by the Free
10 Software Foundation; either version 3, or (at your option) any later
11 version.
12
13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
16 for more details.
17
18 You should have received a copy of the GNU General Public License
19 along with GCC; see the file COPYING3. If not see
20 <http://www.gnu.org/licenses/>. */
21
22 /* This file contains low level functions to manipulate the CFG and analyze it
23 that are aware of the RTL intermediate language.
24
25 Available functionality:
26 - Basic CFG/RTL manipulation API documented in cfghooks.h
27 - CFG-aware instruction chain manipulation
28 delete_insn, delete_insn_chain
29 - Edge splitting and committing to edges
30 insert_insn_on_edge, commit_edge_insertions
31 - CFG updating after insn simplification
32 purge_dead_edges, purge_all_dead_edges
33 - CFG fixing after coarse manipulation
34 fixup_abnormal_edges
35
36 Functions not supposed for generic use:
37 - Infrastructure to determine quickly basic block for insn
38 compute_bb_for_insn, update_bb_for_insn, set_block_for_insn,
39 - Edge redirection with updating and optimizing of insn chain
40 block_label, tidy_fallthru_edge, force_nonfallthru */
41
42 #include "config.h"
43 #include "system.h"
44 #include "coretypes.h"
45 #include "tm.h"
46 #include "tree.h"
47 #include "hard-reg-set.h"
48 #include "basic-block.h"
49 #include "regs.h"
50 #include "flags.h"
51 #include "output.h"
52 #include "function.h"
53 #include "except.h"
54 #include "rtl-error.h"
55 #include "tm_p.h"
56 #include "obstack.h"
57 #include "insn-attr.h"
58 #include "insn-config.h"
59 #include "cfglayout.h"
60 #include "expr.h"
61 #include "target.h"
62 #include "common/common-target.h"
63 #include "cfgloop.h"
64 #include "ggc.h"
65 #include "tree-pass.h"
66 #include "df.h"
67
68 static int can_delete_note_p (const_rtx);
69 static int can_delete_label_p (const_rtx);
70 static basic_block rtl_split_edge (edge);
71 static bool rtl_move_block_after (basic_block, basic_block);
72 static int rtl_verify_flow_info (void);
73 static basic_block cfg_layout_split_block (basic_block, void *);
74 static edge cfg_layout_redirect_edge_and_branch (edge, basic_block);
75 static basic_block cfg_layout_redirect_edge_and_branch_force (edge, basic_block);
76 static void cfg_layout_delete_block (basic_block);
77 static void rtl_delete_block (basic_block);
78 static basic_block rtl_redirect_edge_and_branch_force (edge, basic_block);
79 static edge rtl_redirect_edge_and_branch (edge, basic_block);
80 static basic_block rtl_split_block (basic_block, void *);
81 static void rtl_dump_bb (basic_block, FILE *, int, int);
82 static int rtl_verify_flow_info_1 (void);
83 static void rtl_make_forwarder_block (edge);
84
85 /* Return true if NOTE is not one of the ones that must be kept paired,
86 so that we may simply delete it. */
87
88 static int
can_delete_note_p(const_rtx note)89 can_delete_note_p (const_rtx note)
90 {
91 switch (NOTE_KIND (note))
92 {
93 case NOTE_INSN_DELETED:
94 case NOTE_INSN_BASIC_BLOCK:
95 case NOTE_INSN_EPILOGUE_BEG:
96 return true;
97
98 default:
99 return false;
100 }
101 }
102
103 /* True if a given label can be deleted. */
104
105 static int
can_delete_label_p(const_rtx label)106 can_delete_label_p (const_rtx label)
107 {
108 return (!LABEL_PRESERVE_P (label)
109 /* User declared labels must be preserved. */
110 && LABEL_NAME (label) == 0
111 && !in_expr_list_p (forced_labels, label));
112 }
113
114 /* Delete INSN by patching it out. Return the next insn. */
115
116 rtx
delete_insn(rtx insn)117 delete_insn (rtx insn)
118 {
119 rtx next = NEXT_INSN (insn);
120 rtx note;
121 bool really_delete = true;
122
123 if (LABEL_P (insn))
124 {
125 /* Some labels can't be directly removed from the INSN chain, as they
126 might be references via variables, constant pool etc.
127 Convert them to the special NOTE_INSN_DELETED_LABEL note. */
128 if (! can_delete_label_p (insn))
129 {
130 const char *name = LABEL_NAME (insn);
131
132 really_delete = false;
133 PUT_CODE (insn, NOTE);
134 NOTE_KIND (insn) = NOTE_INSN_DELETED_LABEL;
135 NOTE_DELETED_LABEL_NAME (insn) = name;
136 }
137
138 remove_node_from_expr_list (insn, &nonlocal_goto_handler_labels);
139 }
140
141 if (really_delete)
142 {
143 /* If this insn has already been deleted, something is very wrong. */
144 gcc_assert (!INSN_DELETED_P (insn));
145 remove_insn (insn);
146 INSN_DELETED_P (insn) = 1;
147 }
148
149 /* If deleting a jump, decrement the use count of the label. Deleting
150 the label itself should happen in the normal course of block merging. */
151 if (JUMP_P (insn))
152 {
153 if (JUMP_LABEL (insn)
154 && LABEL_P (JUMP_LABEL (insn)))
155 LABEL_NUSES (JUMP_LABEL (insn))--;
156
157 /* If there are more targets, remove them too. */
158 while ((note
159 = find_reg_note (insn, REG_LABEL_TARGET, NULL_RTX)) != NULL_RTX
160 && LABEL_P (XEXP (note, 0)))
161 {
162 LABEL_NUSES (XEXP (note, 0))--;
163 remove_note (insn, note);
164 }
165 }
166
167 /* Also if deleting any insn that references a label as an operand. */
168 while ((note = find_reg_note (insn, REG_LABEL_OPERAND, NULL_RTX)) != NULL_RTX
169 && LABEL_P (XEXP (note, 0)))
170 {
171 LABEL_NUSES (XEXP (note, 0))--;
172 remove_note (insn, note);
173 }
174
175 if (JUMP_TABLE_DATA_P (insn))
176 {
177 rtx pat = PATTERN (insn);
178 int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC;
179 int len = XVECLEN (pat, diff_vec_p);
180 int i;
181
182 for (i = 0; i < len; i++)
183 {
184 rtx label = XEXP (XVECEXP (pat, diff_vec_p, i), 0);
185
186 /* When deleting code in bulk (e.g. removing many unreachable
187 blocks) we can delete a label that's a target of the vector
188 before deleting the vector itself. */
189 if (!NOTE_P (label))
190 LABEL_NUSES (label)--;
191 }
192 }
193
194 return next;
195 }
196
197 /* Like delete_insn but also purge dead edges from BB. */
198
199 rtx
delete_insn_and_edges(rtx insn)200 delete_insn_and_edges (rtx insn)
201 {
202 rtx x;
203 bool purge = false;
204
205 if (INSN_P (insn)
206 && BLOCK_FOR_INSN (insn)
207 && BB_END (BLOCK_FOR_INSN (insn)) == insn)
208 purge = true;
209 x = delete_insn (insn);
210 if (purge)
211 purge_dead_edges (BLOCK_FOR_INSN (insn));
212 return x;
213 }
214
215 /* Unlink a chain of insns between START and FINISH, leaving notes
216 that must be paired. If CLEAR_BB is true, we set bb field for
217 insns that cannot be removed to NULL. */
218
219 void
delete_insn_chain(rtx start,rtx finish,bool clear_bb)220 delete_insn_chain (rtx start, rtx finish, bool clear_bb)
221 {
222 rtx next;
223
224 /* Unchain the insns one by one. It would be quicker to delete all of these
225 with a single unchaining, rather than one at a time, but we need to keep
226 the NOTE's. */
227 while (1)
228 {
229 next = NEXT_INSN (start);
230 if (NOTE_P (start) && !can_delete_note_p (start))
231 ;
232 else
233 next = delete_insn (start);
234
235 if (clear_bb && !INSN_DELETED_P (start))
236 set_block_for_insn (start, NULL);
237
238 if (start == finish)
239 break;
240 start = next;
241 }
242 }
243
244 /* Create a new basic block consisting of the instructions between HEAD and END
245 inclusive. This function is designed to allow fast BB construction - reuses
246 the note and basic block struct in BB_NOTE, if any and do not grow
247 BASIC_BLOCK chain and should be used directly only by CFG construction code.
248 END can be NULL in to create new empty basic block before HEAD. Both END
249 and HEAD can be NULL to create basic block at the end of INSN chain.
250 AFTER is the basic block we should be put after. */
251
252 basic_block
create_basic_block_structure(rtx head,rtx end,rtx bb_note,basic_block after)253 create_basic_block_structure (rtx head, rtx end, rtx bb_note, basic_block after)
254 {
255 basic_block bb;
256
257 if (bb_note
258 && (bb = NOTE_BASIC_BLOCK (bb_note)) != NULL
259 && bb->aux == NULL)
260 {
261 /* If we found an existing note, thread it back onto the chain. */
262
263 rtx after;
264
265 if (LABEL_P (head))
266 after = head;
267 else
268 {
269 after = PREV_INSN (head);
270 head = bb_note;
271 }
272
273 if (after != bb_note && NEXT_INSN (after) != bb_note)
274 reorder_insns_nobb (bb_note, bb_note, after);
275 }
276 else
277 {
278 /* Otherwise we must create a note and a basic block structure. */
279
280 bb = alloc_block ();
281
282 init_rtl_bb_info (bb);
283 if (!head && !end)
284 head = end = bb_note
285 = emit_note_after (NOTE_INSN_BASIC_BLOCK, get_last_insn ());
286 else if (LABEL_P (head) && end)
287 {
288 bb_note = emit_note_after (NOTE_INSN_BASIC_BLOCK, head);
289 if (head == end)
290 end = bb_note;
291 }
292 else
293 {
294 bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK, head);
295 head = bb_note;
296 if (!end)
297 end = head;
298 }
299
300 NOTE_BASIC_BLOCK (bb_note) = bb;
301 }
302
303 /* Always include the bb note in the block. */
304 if (NEXT_INSN (end) == bb_note)
305 end = bb_note;
306
307 BB_HEAD (bb) = head;
308 BB_END (bb) = end;
309 bb->index = last_basic_block++;
310 bb->flags = BB_NEW | BB_RTL;
311 link_block (bb, after);
312 SET_BASIC_BLOCK (bb->index, bb);
313 df_bb_refs_record (bb->index, false);
314 update_bb_for_insn (bb);
315 BB_SET_PARTITION (bb, BB_UNPARTITIONED);
316
317 /* Tag the block so that we know it has been used when considering
318 other basic block notes. */
319 bb->aux = bb;
320
321 return bb;
322 }
323
324 /* Create new basic block consisting of instructions in between HEAD and END
325 and place it to the BB chain after block AFTER. END can be NULL to
326 create a new empty basic block before HEAD. Both END and HEAD can be
327 NULL to create basic block at the end of INSN chain. */
328
329 static basic_block
rtl_create_basic_block(void * headp,void * endp,basic_block after)330 rtl_create_basic_block (void *headp, void *endp, basic_block after)
331 {
332 rtx head = (rtx) headp, end = (rtx) endp;
333 basic_block bb;
334
335 /* Grow the basic block array if needed. */
336 if ((size_t) last_basic_block >= VEC_length (basic_block, basic_block_info))
337 {
338 size_t new_size = last_basic_block + (last_basic_block + 3) / 4;
339 VEC_safe_grow_cleared (basic_block, gc, basic_block_info, new_size);
340 }
341
342 n_basic_blocks++;
343
344 bb = create_basic_block_structure (head, end, NULL, after);
345 bb->aux = NULL;
346 return bb;
347 }
348
349 static basic_block
cfg_layout_create_basic_block(void * head,void * end,basic_block after)350 cfg_layout_create_basic_block (void *head, void *end, basic_block after)
351 {
352 basic_block newbb = rtl_create_basic_block (head, end, after);
353
354 return newbb;
355 }
356
357 /* Delete the insns in a (non-live) block. We physically delete every
358 non-deleted-note insn, and update the flow graph appropriately.
359
360 Return nonzero if we deleted an exception handler. */
361
362 /* ??? Preserving all such notes strikes me as wrong. It would be nice
363 to post-process the stream to remove empty blocks, loops, ranges, etc. */
364
365 static void
rtl_delete_block(basic_block b)366 rtl_delete_block (basic_block b)
367 {
368 rtx insn, end;
369
370 /* If the head of this block is a CODE_LABEL, then it might be the
371 label for an exception handler which can't be reached. We need
372 to remove the label from the exception_handler_label list. */
373 insn = BB_HEAD (b);
374
375 end = get_last_bb_insn (b);
376
377 /* Selectively delete the entire chain. */
378 BB_HEAD (b) = NULL;
379 delete_insn_chain (insn, end, true);
380
381
382 if (dump_file)
383 fprintf (dump_file, "deleting block %d\n", b->index);
384 df_bb_delete (b->index);
385 }
386
387 /* Records the basic block struct in BLOCK_FOR_INSN for every insn. */
388
389 void
compute_bb_for_insn(void)390 compute_bb_for_insn (void)
391 {
392 basic_block bb;
393
394 FOR_EACH_BB (bb)
395 {
396 rtx end = BB_END (bb);
397 rtx insn;
398
399 for (insn = BB_HEAD (bb); ; insn = NEXT_INSN (insn))
400 {
401 BLOCK_FOR_INSN (insn) = bb;
402 if (insn == end)
403 break;
404 }
405 }
406 }
407
408 /* Release the basic_block_for_insn array. */
409
410 unsigned int
free_bb_for_insn(void)411 free_bb_for_insn (void)
412 {
413 rtx insn;
414 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
415 if (!BARRIER_P (insn))
416 BLOCK_FOR_INSN (insn) = NULL;
417 return 0;
418 }
419
420 static unsigned int
rest_of_pass_free_cfg(void)421 rest_of_pass_free_cfg (void)
422 {
423 #ifdef DELAY_SLOTS
424 /* The resource.c machinery uses DF but the CFG isn't guaranteed to be
425 valid at that point so it would be too late to call df_analyze. */
426 if (optimize > 0 && flag_delayed_branch)
427 {
428 df_note_add_problem ();
429 df_analyze ();
430 }
431 #endif
432
433 free_bb_for_insn ();
434 return 0;
435 }
436
437 struct rtl_opt_pass pass_free_cfg =
438 {
439 {
440 RTL_PASS,
441 "*free_cfg", /* name */
442 NULL, /* gate */
443 rest_of_pass_free_cfg, /* execute */
444 NULL, /* sub */
445 NULL, /* next */
446 0, /* static_pass_number */
447 TV_NONE, /* tv_id */
448 0, /* properties_required */
449 0, /* properties_provided */
450 PROP_cfg, /* properties_destroyed */
451 0, /* todo_flags_start */
452 0, /* todo_flags_finish */
453 }
454 };
455
456 /* Return RTX to emit after when we want to emit code on the entry of function. */
457 rtx
entry_of_function(void)458 entry_of_function (void)
459 {
460 return (n_basic_blocks > NUM_FIXED_BLOCKS ?
461 BB_HEAD (ENTRY_BLOCK_PTR->next_bb) : get_insns ());
462 }
463
464 /* Emit INSN at the entry point of the function, ensuring that it is only
465 executed once per function. */
466 void
emit_insn_at_entry(rtx insn)467 emit_insn_at_entry (rtx insn)
468 {
469 edge_iterator ei = ei_start (ENTRY_BLOCK_PTR->succs);
470 edge e = ei_safe_edge (ei);
471 gcc_assert (e->flags & EDGE_FALLTHRU);
472
473 insert_insn_on_edge (insn, e);
474 commit_edge_insertions ();
475 }
476
477 /* Update BLOCK_FOR_INSN of insns between BEGIN and END
478 (or BARRIER if found) and notify df of the bb change.
479 The insn chain range is inclusive
480 (i.e. both BEGIN and END will be updated. */
481
482 static void
update_bb_for_insn_chain(rtx begin,rtx end,basic_block bb)483 update_bb_for_insn_chain (rtx begin, rtx end, basic_block bb)
484 {
485 rtx insn;
486
487 end = NEXT_INSN (end);
488 for (insn = begin; insn != end; insn = NEXT_INSN (insn))
489 if (!BARRIER_P (insn))
490 df_insn_change_bb (insn, bb);
491 }
492
493 /* Update BLOCK_FOR_INSN of insns in BB to BB,
494 and notify df of the change. */
495
496 void
update_bb_for_insn(basic_block bb)497 update_bb_for_insn (basic_block bb)
498 {
499 update_bb_for_insn_chain (BB_HEAD (bb), BB_END (bb), bb);
500 }
501
502
503 /* Return the NOTE_INSN_BASIC_BLOCK of BB. */
504 rtx
bb_note(basic_block bb)505 bb_note (basic_block bb)
506 {
507 rtx note;
508
509 note = BB_HEAD (bb);
510 if (LABEL_P (note))
511 note = NEXT_INSN (note);
512
513 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (note));
514 return note;
515 }
516
517 /* Return the INSN immediately following the NOTE_INSN_BASIC_BLOCK
518 note associated with the BLOCK. */
519
520 static rtx
first_insn_after_basic_block_note(basic_block block)521 first_insn_after_basic_block_note (basic_block block)
522 {
523 rtx insn;
524
525 /* Get the first instruction in the block. */
526 insn = BB_HEAD (block);
527
528 if (insn == NULL_RTX)
529 return NULL_RTX;
530 if (LABEL_P (insn))
531 insn = NEXT_INSN (insn);
532 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (insn));
533
534 return NEXT_INSN (insn);
535 }
536
537 /* Creates a new basic block just after basic block B by splitting
538 everything after specified instruction I. */
539
540 static basic_block
rtl_split_block(basic_block bb,void * insnp)541 rtl_split_block (basic_block bb, void *insnp)
542 {
543 basic_block new_bb;
544 rtx insn = (rtx) insnp;
545 edge e;
546 edge_iterator ei;
547
548 if (!insn)
549 {
550 insn = first_insn_after_basic_block_note (bb);
551
552 if (insn)
553 {
554 rtx next = insn;
555
556 insn = PREV_INSN (insn);
557
558 /* If the block contains only debug insns, insn would have
559 been NULL in a non-debug compilation, and then we'd end
560 up emitting a DELETED note. For -fcompare-debug
561 stability, emit the note too. */
562 if (insn != BB_END (bb)
563 && DEBUG_INSN_P (next)
564 && DEBUG_INSN_P (BB_END (bb)))
565 {
566 while (next != BB_END (bb) && DEBUG_INSN_P (next))
567 next = NEXT_INSN (next);
568
569 if (next == BB_END (bb))
570 emit_note_after (NOTE_INSN_DELETED, next);
571 }
572 }
573 else
574 insn = get_last_insn ();
575 }
576
577 /* We probably should check type of the insn so that we do not create
578 inconsistent cfg. It is checked in verify_flow_info anyway, so do not
579 bother. */
580 if (insn == BB_END (bb))
581 emit_note_after (NOTE_INSN_DELETED, insn);
582
583 /* Create the new basic block. */
584 new_bb = create_basic_block (NEXT_INSN (insn), BB_END (bb), bb);
585 BB_COPY_PARTITION (new_bb, bb);
586 BB_END (bb) = insn;
587
588 /* Redirect the outgoing edges. */
589 new_bb->succs = bb->succs;
590 bb->succs = NULL;
591 FOR_EACH_EDGE (e, ei, new_bb->succs)
592 e->src = new_bb;
593
594 /* The new block starts off being dirty. */
595 df_set_bb_dirty (bb);
596 return new_bb;
597 }
598
599 /* Blocks A and B are to be merged into a single block A. The insns
600 are already contiguous. */
601
602 static void
rtl_merge_blocks(basic_block a,basic_block b)603 rtl_merge_blocks (basic_block a, basic_block b)
604 {
605 rtx b_head = BB_HEAD (b), b_end = BB_END (b), a_end = BB_END (a);
606 rtx del_first = NULL_RTX, del_last = NULL_RTX;
607 rtx b_debug_start = b_end, b_debug_end = b_end;
608 bool forwarder_p = (b->flags & BB_FORWARDER_BLOCK) != 0;
609 int b_empty = 0;
610
611 if (dump_file)
612 fprintf (dump_file, "Merging block %d into block %d...\n", b->index,
613 a->index);
614
615 while (DEBUG_INSN_P (b_end))
616 b_end = PREV_INSN (b_debug_start = b_end);
617
618 /* If there was a CODE_LABEL beginning B, delete it. */
619 if (LABEL_P (b_head))
620 {
621 /* Detect basic blocks with nothing but a label. This can happen
622 in particular at the end of a function. */
623 if (b_head == b_end)
624 b_empty = 1;
625
626 del_first = del_last = b_head;
627 b_head = NEXT_INSN (b_head);
628 }
629
630 /* Delete the basic block note and handle blocks containing just that
631 note. */
632 if (NOTE_INSN_BASIC_BLOCK_P (b_head))
633 {
634 if (b_head == b_end)
635 b_empty = 1;
636 if (! del_last)
637 del_first = b_head;
638
639 del_last = b_head;
640 b_head = NEXT_INSN (b_head);
641 }
642
643 /* If there was a jump out of A, delete it. */
644 if (JUMP_P (a_end))
645 {
646 rtx prev;
647
648 for (prev = PREV_INSN (a_end); ; prev = PREV_INSN (prev))
649 if (!NOTE_P (prev)
650 || NOTE_INSN_BASIC_BLOCK_P (prev)
651 || prev == BB_HEAD (a))
652 break;
653
654 del_first = a_end;
655
656 #ifdef HAVE_cc0
657 /* If this was a conditional jump, we need to also delete
658 the insn that set cc0. */
659 if (only_sets_cc0_p (prev))
660 {
661 rtx tmp = prev;
662
663 prev = prev_nonnote_insn (prev);
664 if (!prev)
665 prev = BB_HEAD (a);
666 del_first = tmp;
667 }
668 #endif
669
670 a_end = PREV_INSN (del_first);
671 }
672 else if (BARRIER_P (NEXT_INSN (a_end)))
673 del_first = NEXT_INSN (a_end);
674
675 /* Delete everything marked above as well as crap that might be
676 hanging out between the two blocks. */
677 BB_HEAD (b) = NULL;
678 delete_insn_chain (del_first, del_last, true);
679
680 /* Reassociate the insns of B with A. */
681 if (!b_empty)
682 {
683 update_bb_for_insn_chain (a_end, b_debug_end, a);
684
685 a_end = b_debug_end;
686 }
687 else if (b_end != b_debug_end)
688 {
689 /* Move any deleted labels and other notes between the end of A
690 and the debug insns that make up B after the debug insns,
691 bringing the debug insns into A while keeping the notes after
692 the end of A. */
693 if (NEXT_INSN (a_end) != b_debug_start)
694 reorder_insns_nobb (NEXT_INSN (a_end), PREV_INSN (b_debug_start),
695 b_debug_end);
696 update_bb_for_insn_chain (b_debug_start, b_debug_end, a);
697 a_end = b_debug_end;
698 }
699
700 df_bb_delete (b->index);
701 BB_END (a) = a_end;
702
703 /* If B was a forwarder block, propagate the locus on the edge. */
704 if (forwarder_p && !EDGE_SUCC (b, 0)->goto_locus)
705 EDGE_SUCC (b, 0)->goto_locus = EDGE_SUCC (a, 0)->goto_locus;
706
707 if (dump_file)
708 fprintf (dump_file, "Merged blocks %d and %d.\n", a->index, b->index);
709 }
710
711
712 /* Return true when block A and B can be merged. */
713
714 static bool
rtl_can_merge_blocks(basic_block a,basic_block b)715 rtl_can_merge_blocks (basic_block a, basic_block b)
716 {
717 /* If we are partitioning hot/cold basic blocks, we don't want to
718 mess up unconditional or indirect jumps that cross between hot
719 and cold sections.
720
721 Basic block partitioning may result in some jumps that appear to
722 be optimizable (or blocks that appear to be mergeable), but which really
723 must be left untouched (they are required to make it safely across
724 partition boundaries). See the comments at the top of
725 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
726
727 if (BB_PARTITION (a) != BB_PARTITION (b))
728 return false;
729
730 /* There must be exactly one edge in between the blocks. */
731 return (single_succ_p (a)
732 && single_succ (a) == b
733 && single_pred_p (b)
734 && a != b
735 /* Must be simple edge. */
736 && !(single_succ_edge (a)->flags & EDGE_COMPLEX)
737 && a->next_bb == b
738 && a != ENTRY_BLOCK_PTR && b != EXIT_BLOCK_PTR
739 /* If the jump insn has side effects,
740 we can't kill the edge. */
741 && (!JUMP_P (BB_END (a))
742 || (reload_completed
743 ? simplejump_p (BB_END (a)) : onlyjump_p (BB_END (a)))));
744 }
745
746 /* Return the label in the head of basic block BLOCK. Create one if it doesn't
747 exist. */
748
749 rtx
block_label(basic_block block)750 block_label (basic_block block)
751 {
752 if (block == EXIT_BLOCK_PTR)
753 return NULL_RTX;
754
755 if (!LABEL_P (BB_HEAD (block)))
756 {
757 BB_HEAD (block) = emit_label_before (gen_label_rtx (), BB_HEAD (block));
758 }
759
760 return BB_HEAD (block);
761 }
762
763 /* Attempt to perform edge redirection by replacing possibly complex jump
764 instruction by unconditional jump or removing jump completely. This can
765 apply only if all edges now point to the same block. The parameters and
766 return values are equivalent to redirect_edge_and_branch. */
767
768 edge
try_redirect_by_replacing_jump(edge e,basic_block target,bool in_cfglayout)769 try_redirect_by_replacing_jump (edge e, basic_block target, bool in_cfglayout)
770 {
771 basic_block src = e->src;
772 rtx insn = BB_END (src), kill_from;
773 rtx set;
774 int fallthru = 0;
775
776 /* If we are partitioning hot/cold basic blocks, we don't want to
777 mess up unconditional or indirect jumps that cross between hot
778 and cold sections.
779
780 Basic block partitioning may result in some jumps that appear to
781 be optimizable (or blocks that appear to be mergeable), but which really
782 must be left untouched (they are required to make it safely across
783 partition boundaries). See the comments at the top of
784 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
785
786 if (find_reg_note (insn, REG_CROSSING_JUMP, NULL_RTX)
787 || BB_PARTITION (src) != BB_PARTITION (target))
788 return NULL;
789
790 /* We can replace or remove a complex jump only when we have exactly
791 two edges. Also, if we have exactly one outgoing edge, we can
792 redirect that. */
793 if (EDGE_COUNT (src->succs) >= 3
794 /* Verify that all targets will be TARGET. Specifically, the
795 edge that is not E must also go to TARGET. */
796 || (EDGE_COUNT (src->succs) == 2
797 && EDGE_SUCC (src, EDGE_SUCC (src, 0) == e)->dest != target))
798 return NULL;
799
800 if (!onlyjump_p (insn))
801 return NULL;
802 if ((!optimize || reload_completed) && tablejump_p (insn, NULL, NULL))
803 return NULL;
804
805 /* Avoid removing branch with side effects. */
806 set = single_set (insn);
807 if (!set || side_effects_p (set))
808 return NULL;
809
810 /* In case we zap a conditional jump, we'll need to kill
811 the cc0 setter too. */
812 kill_from = insn;
813 #ifdef HAVE_cc0
814 if (reg_mentioned_p (cc0_rtx, PATTERN (insn))
815 && only_sets_cc0_p (PREV_INSN (insn)))
816 kill_from = PREV_INSN (insn);
817 #endif
818
819 /* See if we can create the fallthru edge. */
820 if (in_cfglayout || can_fallthru (src, target))
821 {
822 if (dump_file)
823 fprintf (dump_file, "Removing jump %i.\n", INSN_UID (insn));
824 fallthru = 1;
825
826 /* Selectively unlink whole insn chain. */
827 if (in_cfglayout)
828 {
829 rtx insn = src->il.rtl->footer;
830
831 delete_insn_chain (kill_from, BB_END (src), false);
832
833 /* Remove barriers but keep jumptables. */
834 while (insn)
835 {
836 if (BARRIER_P (insn))
837 {
838 if (PREV_INSN (insn))
839 NEXT_INSN (PREV_INSN (insn)) = NEXT_INSN (insn);
840 else
841 src->il.rtl->footer = NEXT_INSN (insn);
842 if (NEXT_INSN (insn))
843 PREV_INSN (NEXT_INSN (insn)) = PREV_INSN (insn);
844 }
845 if (LABEL_P (insn))
846 break;
847 insn = NEXT_INSN (insn);
848 }
849 }
850 else
851 delete_insn_chain (kill_from, PREV_INSN (BB_HEAD (target)),
852 false);
853 }
854
855 /* If this already is simplejump, redirect it. */
856 else if (simplejump_p (insn))
857 {
858 if (e->dest == target)
859 return NULL;
860 if (dump_file)
861 fprintf (dump_file, "Redirecting jump %i from %i to %i.\n",
862 INSN_UID (insn), e->dest->index, target->index);
863 if (!redirect_jump (insn, block_label (target), 0))
864 {
865 gcc_assert (target == EXIT_BLOCK_PTR);
866 return NULL;
867 }
868 }
869
870 /* Cannot do anything for target exit block. */
871 else if (target == EXIT_BLOCK_PTR)
872 return NULL;
873
874 /* Or replace possibly complicated jump insn by simple jump insn. */
875 else
876 {
877 rtx target_label = block_label (target);
878 rtx barrier, label, table;
879
880 emit_jump_insn_after_noloc (gen_jump (target_label), insn);
881 JUMP_LABEL (BB_END (src)) = target_label;
882 LABEL_NUSES (target_label)++;
883 if (dump_file)
884 fprintf (dump_file, "Replacing insn %i by jump %i\n",
885 INSN_UID (insn), INSN_UID (BB_END (src)));
886
887
888 delete_insn_chain (kill_from, insn, false);
889
890 /* Recognize a tablejump that we are converting to a
891 simple jump and remove its associated CODE_LABEL
892 and ADDR_VEC or ADDR_DIFF_VEC. */
893 if (tablejump_p (insn, &label, &table))
894 delete_insn_chain (label, table, false);
895
896 barrier = next_nonnote_insn (BB_END (src));
897 if (!barrier || !BARRIER_P (barrier))
898 emit_barrier_after (BB_END (src));
899 else
900 {
901 if (barrier != NEXT_INSN (BB_END (src)))
902 {
903 /* Move the jump before barrier so that the notes
904 which originally were or were created before jump table are
905 inside the basic block. */
906 rtx new_insn = BB_END (src);
907
908 update_bb_for_insn_chain (NEXT_INSN (BB_END (src)),
909 PREV_INSN (barrier), src);
910
911 NEXT_INSN (PREV_INSN (new_insn)) = NEXT_INSN (new_insn);
912 PREV_INSN (NEXT_INSN (new_insn)) = PREV_INSN (new_insn);
913
914 NEXT_INSN (new_insn) = barrier;
915 NEXT_INSN (PREV_INSN (barrier)) = new_insn;
916
917 PREV_INSN (new_insn) = PREV_INSN (barrier);
918 PREV_INSN (barrier) = new_insn;
919 }
920 }
921 }
922
923 /* Keep only one edge out and set proper flags. */
924 if (!single_succ_p (src))
925 remove_edge (e);
926 gcc_assert (single_succ_p (src));
927
928 e = single_succ_edge (src);
929 if (fallthru)
930 e->flags = EDGE_FALLTHRU;
931 else
932 e->flags = 0;
933
934 e->probability = REG_BR_PROB_BASE;
935 e->count = src->count;
936
937 if (e->dest != target)
938 redirect_edge_succ (e, target);
939 return e;
940 }
941
942 /* Subroutine of redirect_branch_edge that tries to patch the jump
943 instruction INSN so that it reaches block NEW. Do this
944 only when it originally reached block OLD. Return true if this
945 worked or the original target wasn't OLD, return false if redirection
946 doesn't work. */
947
948 static bool
patch_jump_insn(rtx insn,rtx old_label,basic_block new_bb)949 patch_jump_insn (rtx insn, rtx old_label, basic_block new_bb)
950 {
951 rtx tmp;
952 /* Recognize a tablejump and adjust all matching cases. */
953 if (tablejump_p (insn, NULL, &tmp))
954 {
955 rtvec vec;
956 int j;
957 rtx new_label = block_label (new_bb);
958
959 if (new_bb == EXIT_BLOCK_PTR)
960 return false;
961 if (GET_CODE (PATTERN (tmp)) == ADDR_VEC)
962 vec = XVEC (PATTERN (tmp), 0);
963 else
964 vec = XVEC (PATTERN (tmp), 1);
965
966 for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j)
967 if (XEXP (RTVEC_ELT (vec, j), 0) == old_label)
968 {
969 RTVEC_ELT (vec, j) = gen_rtx_LABEL_REF (Pmode, new_label);
970 --LABEL_NUSES (old_label);
971 ++LABEL_NUSES (new_label);
972 }
973
974 /* Handle casesi dispatch insns. */
975 if ((tmp = single_set (insn)) != NULL
976 && SET_DEST (tmp) == pc_rtx
977 && GET_CODE (SET_SRC (tmp)) == IF_THEN_ELSE
978 && GET_CODE (XEXP (SET_SRC (tmp), 2)) == LABEL_REF
979 && XEXP (XEXP (SET_SRC (tmp), 2), 0) == old_label)
980 {
981 XEXP (SET_SRC (tmp), 2) = gen_rtx_LABEL_REF (Pmode,
982 new_label);
983 --LABEL_NUSES (old_label);
984 ++LABEL_NUSES (new_label);
985 }
986 }
987 else if ((tmp = extract_asm_operands (PATTERN (insn))) != NULL)
988 {
989 int i, n = ASM_OPERANDS_LABEL_LENGTH (tmp);
990 rtx new_label, note;
991
992 if (new_bb == EXIT_BLOCK_PTR)
993 return false;
994 new_label = block_label (new_bb);
995
996 for (i = 0; i < n; ++i)
997 {
998 rtx old_ref = ASM_OPERANDS_LABEL (tmp, i);
999 gcc_assert (GET_CODE (old_ref) == LABEL_REF);
1000 if (XEXP (old_ref, 0) == old_label)
1001 {
1002 ASM_OPERANDS_LABEL (tmp, i)
1003 = gen_rtx_LABEL_REF (Pmode, new_label);
1004 --LABEL_NUSES (old_label);
1005 ++LABEL_NUSES (new_label);
1006 }
1007 }
1008
1009 if (JUMP_LABEL (insn) == old_label)
1010 {
1011 JUMP_LABEL (insn) = new_label;
1012 note = find_reg_note (insn, REG_LABEL_TARGET, new_label);
1013 if (note)
1014 remove_note (insn, note);
1015 }
1016 else
1017 {
1018 note = find_reg_note (insn, REG_LABEL_TARGET, old_label);
1019 if (note)
1020 remove_note (insn, note);
1021 if (JUMP_LABEL (insn) != new_label
1022 && !find_reg_note (insn, REG_LABEL_TARGET, new_label))
1023 add_reg_note (insn, REG_LABEL_TARGET, new_label);
1024 }
1025 while ((note = find_reg_note (insn, REG_LABEL_OPERAND, old_label))
1026 != NULL_RTX)
1027 XEXP (note, 0) = new_label;
1028 }
1029 else
1030 {
1031 /* ?? We may play the games with moving the named labels from
1032 one basic block to the other in case only one computed_jump is
1033 available. */
1034 if (computed_jump_p (insn)
1035 /* A return instruction can't be redirected. */
1036 || returnjump_p (insn))
1037 return false;
1038
1039 if (!currently_expanding_to_rtl || JUMP_LABEL (insn) == old_label)
1040 {
1041 /* If the insn doesn't go where we think, we're confused. */
1042 gcc_assert (JUMP_LABEL (insn) == old_label);
1043
1044 /* If the substitution doesn't succeed, die. This can happen
1045 if the back end emitted unrecognizable instructions or if
1046 target is exit block on some arches. */
1047 if (!redirect_jump (insn, block_label (new_bb), 0))
1048 {
1049 gcc_assert (new_bb == EXIT_BLOCK_PTR);
1050 return false;
1051 }
1052 }
1053 }
1054 return true;
1055 }
1056
1057
1058 /* Redirect edge representing branch of (un)conditional jump or tablejump,
1059 NULL on failure */
1060 static edge
redirect_branch_edge(edge e,basic_block target)1061 redirect_branch_edge (edge e, basic_block target)
1062 {
1063 rtx old_label = BB_HEAD (e->dest);
1064 basic_block src = e->src;
1065 rtx insn = BB_END (src);
1066
1067 /* We can only redirect non-fallthru edges of jump insn. */
1068 if (e->flags & EDGE_FALLTHRU)
1069 return NULL;
1070 else if (!JUMP_P (insn) && !currently_expanding_to_rtl)
1071 return NULL;
1072
1073 if (!currently_expanding_to_rtl)
1074 {
1075 if (!patch_jump_insn (insn, old_label, target))
1076 return NULL;
1077 }
1078 else
1079 /* When expanding this BB might actually contain multiple
1080 jumps (i.e. not yet split by find_many_sub_basic_blocks).
1081 Redirect all of those that match our label. */
1082 FOR_BB_INSNS (src, insn)
1083 if (JUMP_P (insn) && !patch_jump_insn (insn, old_label, target))
1084 return NULL;
1085
1086 if (dump_file)
1087 fprintf (dump_file, "Edge %i->%i redirected to %i\n",
1088 e->src->index, e->dest->index, target->index);
1089
1090 if (e->dest != target)
1091 e = redirect_edge_succ_nodup (e, target);
1092
1093 return e;
1094 }
1095
1096 /* Attempt to change code to redirect edge E to TARGET. Don't do that on
1097 expense of adding new instructions or reordering basic blocks.
1098
1099 Function can be also called with edge destination equivalent to the TARGET.
1100 Then it should try the simplifications and do nothing if none is possible.
1101
1102 Return edge representing the branch if transformation succeeded. Return NULL
1103 on failure.
1104 We still return NULL in case E already destinated TARGET and we didn't
1105 managed to simplify instruction stream. */
1106
1107 static edge
rtl_redirect_edge_and_branch(edge e,basic_block target)1108 rtl_redirect_edge_and_branch (edge e, basic_block target)
1109 {
1110 edge ret;
1111 basic_block src = e->src;
1112
1113 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
1114 return NULL;
1115
1116 if (e->dest == target)
1117 return e;
1118
1119 if ((ret = try_redirect_by_replacing_jump (e, target, false)) != NULL)
1120 {
1121 df_set_bb_dirty (src);
1122 return ret;
1123 }
1124
1125 ret = redirect_branch_edge (e, target);
1126 if (!ret)
1127 return NULL;
1128
1129 df_set_bb_dirty (src);
1130 return ret;
1131 }
1132
1133 /* Like force_nonfallthru below, but additionally performs redirection
1134 Used by redirect_edge_and_branch_force. JUMP_LABEL is used only
1135 when redirecting to the EXIT_BLOCK, it is either ret_rtx or
1136 simple_return_rtx, indicating which kind of returnjump to create.
1137 It should be NULL otherwise. */
1138
1139 basic_block
force_nonfallthru_and_redirect(edge e,basic_block target,rtx jump_label)1140 force_nonfallthru_and_redirect (edge e, basic_block target, rtx jump_label)
1141 {
1142 basic_block jump_block, new_bb = NULL, src = e->src;
1143 rtx note;
1144 edge new_edge;
1145 int abnormal_edge_flags = 0;
1146 bool asm_goto_edge = false;
1147 int loc;
1148
1149 /* In the case the last instruction is conditional jump to the next
1150 instruction, first redirect the jump itself and then continue
1151 by creating a basic block afterwards to redirect fallthru edge. */
1152 if (e->src != ENTRY_BLOCK_PTR && e->dest != EXIT_BLOCK_PTR
1153 && any_condjump_p (BB_END (e->src))
1154 && JUMP_LABEL (BB_END (e->src)) == BB_HEAD (e->dest))
1155 {
1156 rtx note;
1157 edge b = unchecked_make_edge (e->src, target, 0);
1158 bool redirected;
1159
1160 redirected = redirect_jump (BB_END (e->src), block_label (target), 0);
1161 gcc_assert (redirected);
1162
1163 note = find_reg_note (BB_END (e->src), REG_BR_PROB, NULL_RTX);
1164 if (note)
1165 {
1166 int prob = INTVAL (XEXP (note, 0));
1167
1168 b->probability = prob;
1169 b->count = e->count * prob / REG_BR_PROB_BASE;
1170 e->probability -= e->probability;
1171 e->count -= b->count;
1172 if (e->probability < 0)
1173 e->probability = 0;
1174 if (e->count < 0)
1175 e->count = 0;
1176 }
1177 }
1178
1179 if (e->flags & EDGE_ABNORMAL)
1180 {
1181 /* Irritating special case - fallthru edge to the same block as abnormal
1182 edge.
1183 We can't redirect abnormal edge, but we still can split the fallthru
1184 one and create separate abnormal edge to original destination.
1185 This allows bb-reorder to make such edge non-fallthru. */
1186 gcc_assert (e->dest == target);
1187 abnormal_edge_flags = e->flags & ~(EDGE_FALLTHRU | EDGE_CAN_FALLTHRU);
1188 e->flags &= EDGE_FALLTHRU | EDGE_CAN_FALLTHRU;
1189 }
1190 else
1191 {
1192 gcc_assert (e->flags & EDGE_FALLTHRU);
1193 if (e->src == ENTRY_BLOCK_PTR)
1194 {
1195 /* We can't redirect the entry block. Create an empty block
1196 at the start of the function which we use to add the new
1197 jump. */
1198 edge tmp;
1199 edge_iterator ei;
1200 bool found = false;
1201
1202 basic_block bb = create_basic_block (BB_HEAD (e->dest), NULL, ENTRY_BLOCK_PTR);
1203
1204 /* Change the existing edge's source to be the new block, and add
1205 a new edge from the entry block to the new block. */
1206 e->src = bb;
1207 for (ei = ei_start (ENTRY_BLOCK_PTR->succs); (tmp = ei_safe_edge (ei)); )
1208 {
1209 if (tmp == e)
1210 {
1211 VEC_unordered_remove (edge, ENTRY_BLOCK_PTR->succs, ei.index);
1212 found = true;
1213 break;
1214 }
1215 else
1216 ei_next (&ei);
1217 }
1218
1219 gcc_assert (found);
1220
1221 VEC_safe_push (edge, gc, bb->succs, e);
1222 make_single_succ_edge (ENTRY_BLOCK_PTR, bb, EDGE_FALLTHRU);
1223 }
1224 }
1225
1226 /* If e->src ends with asm goto, see if any of the ASM_OPERANDS_LABELs
1227 don't point to the target or fallthru label. */
1228 if (JUMP_P (BB_END (e->src))
1229 && target != EXIT_BLOCK_PTR
1230 && (e->flags & EDGE_FALLTHRU)
1231 && (note = extract_asm_operands (PATTERN (BB_END (e->src)))))
1232 {
1233 int i, n = ASM_OPERANDS_LABEL_LENGTH (note);
1234 bool adjust_jump_target = false;
1235
1236 for (i = 0; i < n; ++i)
1237 {
1238 if (XEXP (ASM_OPERANDS_LABEL (note, i), 0) == BB_HEAD (e->dest))
1239 {
1240 LABEL_NUSES (XEXP (ASM_OPERANDS_LABEL (note, i), 0))--;
1241 XEXP (ASM_OPERANDS_LABEL (note, i), 0) = block_label (target);
1242 LABEL_NUSES (XEXP (ASM_OPERANDS_LABEL (note, i), 0))++;
1243 adjust_jump_target = true;
1244 }
1245 if (XEXP (ASM_OPERANDS_LABEL (note, i), 0) == BB_HEAD (target))
1246 asm_goto_edge = true;
1247 }
1248 if (adjust_jump_target)
1249 {
1250 rtx insn = BB_END (e->src), note;
1251 rtx old_label = BB_HEAD (e->dest);
1252 rtx new_label = BB_HEAD (target);
1253
1254 if (JUMP_LABEL (insn) == old_label)
1255 {
1256 JUMP_LABEL (insn) = new_label;
1257 note = find_reg_note (insn, REG_LABEL_TARGET, new_label);
1258 if (note)
1259 remove_note (insn, note);
1260 }
1261 else
1262 {
1263 note = find_reg_note (insn, REG_LABEL_TARGET, old_label);
1264 if (note)
1265 remove_note (insn, note);
1266 if (JUMP_LABEL (insn) != new_label
1267 && !find_reg_note (insn, REG_LABEL_TARGET, new_label))
1268 add_reg_note (insn, REG_LABEL_TARGET, new_label);
1269 }
1270 while ((note = find_reg_note (insn, REG_LABEL_OPERAND, old_label))
1271 != NULL_RTX)
1272 XEXP (note, 0) = new_label;
1273 }
1274 }
1275
1276 if (EDGE_COUNT (e->src->succs) >= 2 || abnormal_edge_flags || asm_goto_edge)
1277 {
1278 gcov_type count = e->count;
1279 int probability = e->probability;
1280 /* Create the new structures. */
1281
1282 /* If the old block ended with a tablejump, skip its table
1283 by searching forward from there. Otherwise start searching
1284 forward from the last instruction of the old block. */
1285 if (!tablejump_p (BB_END (e->src), NULL, ¬e))
1286 note = BB_END (e->src);
1287 note = NEXT_INSN (note);
1288
1289 jump_block = create_basic_block (note, NULL, e->src);
1290 jump_block->count = count;
1291 jump_block->frequency = EDGE_FREQUENCY (e);
1292 jump_block->loop_depth = target->loop_depth;
1293
1294 /* Make sure new block ends up in correct hot/cold section. */
1295
1296 BB_COPY_PARTITION (jump_block, e->src);
1297 if (flag_reorder_blocks_and_partition
1298 && targetm_common.have_named_sections
1299 && JUMP_P (BB_END (jump_block))
1300 && !any_condjump_p (BB_END (jump_block))
1301 && (EDGE_SUCC (jump_block, 0)->flags & EDGE_CROSSING))
1302 add_reg_note (BB_END (jump_block), REG_CROSSING_JUMP, NULL_RTX);
1303
1304 /* Wire edge in. */
1305 new_edge = make_edge (e->src, jump_block, EDGE_FALLTHRU);
1306 new_edge->probability = probability;
1307 new_edge->count = count;
1308
1309 /* Redirect old edge. */
1310 redirect_edge_pred (e, jump_block);
1311 e->probability = REG_BR_PROB_BASE;
1312
1313 /* If asm goto has any label refs to target's label,
1314 add also edge from asm goto bb to target. */
1315 if (asm_goto_edge)
1316 {
1317 new_edge->probability /= 2;
1318 new_edge->count /= 2;
1319 jump_block->count /= 2;
1320 jump_block->frequency /= 2;
1321 new_edge = make_edge (new_edge->src, target,
1322 e->flags & ~EDGE_FALLTHRU);
1323 new_edge->probability = probability - probability / 2;
1324 new_edge->count = count - count / 2;
1325 }
1326
1327 new_bb = jump_block;
1328 }
1329 else
1330 jump_block = e->src;
1331
1332 if (e->goto_locus && e->goto_block == NULL)
1333 loc = e->goto_locus;
1334 else
1335 loc = 0;
1336 e->flags &= ~EDGE_FALLTHRU;
1337 if (target == EXIT_BLOCK_PTR)
1338 {
1339 if (jump_label == ret_rtx)
1340 {
1341 #ifdef HAVE_return
1342 emit_jump_insn_after_setloc (gen_return (), BB_END (jump_block), loc);
1343 #else
1344 gcc_unreachable ();
1345 #endif
1346 }
1347 else
1348 {
1349 gcc_assert (jump_label == simple_return_rtx);
1350 #ifdef HAVE_simple_return
1351 emit_jump_insn_after_setloc (gen_simple_return (),
1352 BB_END (jump_block), loc);
1353 #else
1354 gcc_unreachable ();
1355 #endif
1356 }
1357 set_return_jump_label (BB_END (jump_block));
1358 }
1359 else
1360 {
1361 rtx label = block_label (target);
1362 emit_jump_insn_after_setloc (gen_jump (label), BB_END (jump_block), loc);
1363 JUMP_LABEL (BB_END (jump_block)) = label;
1364 LABEL_NUSES (label)++;
1365 }
1366
1367 emit_barrier_after (BB_END (jump_block));
1368 redirect_edge_succ_nodup (e, target);
1369
1370 if (abnormal_edge_flags)
1371 make_edge (src, target, abnormal_edge_flags);
1372
1373 df_mark_solutions_dirty ();
1374 return new_bb;
1375 }
1376
1377 /* Edge E is assumed to be fallthru edge. Emit needed jump instruction
1378 (and possibly create new basic block) to make edge non-fallthru.
1379 Return newly created BB or NULL if none. */
1380
1381 static basic_block
rtl_force_nonfallthru(edge e)1382 rtl_force_nonfallthru (edge e)
1383 {
1384 return force_nonfallthru_and_redirect (e, e->dest, NULL_RTX);
1385 }
1386
1387 /* Redirect edge even at the expense of creating new jump insn or
1388 basic block. Return new basic block if created, NULL otherwise.
1389 Conversion must be possible. */
1390
1391 static basic_block
rtl_redirect_edge_and_branch_force(edge e,basic_block target)1392 rtl_redirect_edge_and_branch_force (edge e, basic_block target)
1393 {
1394 if (redirect_edge_and_branch (e, target)
1395 || e->dest == target)
1396 return NULL;
1397
1398 /* In case the edge redirection failed, try to force it to be non-fallthru
1399 and redirect newly created simplejump. */
1400 df_set_bb_dirty (e->src);
1401 return force_nonfallthru_and_redirect (e, target, NULL_RTX);
1402 }
1403
1404 /* The given edge should potentially be a fallthru edge. If that is in
1405 fact true, delete the jump and barriers that are in the way. */
1406
1407 static void
rtl_tidy_fallthru_edge(edge e)1408 rtl_tidy_fallthru_edge (edge e)
1409 {
1410 rtx q;
1411 basic_block b = e->src, c = b->next_bb;
1412
1413 /* ??? In a late-running flow pass, other folks may have deleted basic
1414 blocks by nopping out blocks, leaving multiple BARRIERs between here
1415 and the target label. They ought to be chastised and fixed.
1416
1417 We can also wind up with a sequence of undeletable labels between
1418 one block and the next.
1419
1420 So search through a sequence of barriers, labels, and notes for
1421 the head of block C and assert that we really do fall through. */
1422
1423 for (q = NEXT_INSN (BB_END (b)); q != BB_HEAD (c); q = NEXT_INSN (q))
1424 if (INSN_P (q))
1425 return;
1426
1427 /* Remove what will soon cease being the jump insn from the source block.
1428 If block B consisted only of this single jump, turn it into a deleted
1429 note. */
1430 q = BB_END (b);
1431 if (JUMP_P (q)
1432 && onlyjump_p (q)
1433 && (any_uncondjump_p (q)
1434 || single_succ_p (b)))
1435 {
1436 #ifdef HAVE_cc0
1437 /* If this was a conditional jump, we need to also delete
1438 the insn that set cc0. */
1439 if (any_condjump_p (q) && only_sets_cc0_p (PREV_INSN (q)))
1440 q = PREV_INSN (q);
1441 #endif
1442
1443 q = PREV_INSN (q);
1444 }
1445
1446 /* Selectively unlink the sequence. */
1447 if (q != PREV_INSN (BB_HEAD (c)))
1448 delete_insn_chain (NEXT_INSN (q), PREV_INSN (BB_HEAD (c)), false);
1449
1450 e->flags |= EDGE_FALLTHRU;
1451 }
1452
1453 /* Should move basic block BB after basic block AFTER. NIY. */
1454
1455 static bool
rtl_move_block_after(basic_block bb ATTRIBUTE_UNUSED,basic_block after ATTRIBUTE_UNUSED)1456 rtl_move_block_after (basic_block bb ATTRIBUTE_UNUSED,
1457 basic_block after ATTRIBUTE_UNUSED)
1458 {
1459 return false;
1460 }
1461
1462 /* Split a (typically critical) edge. Return the new block.
1463 The edge must not be abnormal.
1464
1465 ??? The code generally expects to be called on critical edges.
1466 The case of a block ending in an unconditional jump to a
1467 block with multiple predecessors is not handled optimally. */
1468
1469 static basic_block
rtl_split_edge(edge edge_in)1470 rtl_split_edge (edge edge_in)
1471 {
1472 basic_block bb;
1473 rtx before;
1474
1475 /* Abnormal edges cannot be split. */
1476 gcc_assert (!(edge_in->flags & EDGE_ABNORMAL));
1477
1478 /* We are going to place the new block in front of edge destination.
1479 Avoid existence of fallthru predecessors. */
1480 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
1481 {
1482 edge e = find_fallthru_edge (edge_in->dest->preds);
1483
1484 if (e)
1485 force_nonfallthru (e);
1486 }
1487
1488 /* Create the basic block note. */
1489 if (edge_in->dest != EXIT_BLOCK_PTR)
1490 before = BB_HEAD (edge_in->dest);
1491 else
1492 before = NULL_RTX;
1493
1494 /* If this is a fall through edge to the exit block, the blocks might be
1495 not adjacent, and the right place is after the source. */
1496 if ((edge_in->flags & EDGE_FALLTHRU) && edge_in->dest == EXIT_BLOCK_PTR)
1497 {
1498 before = NEXT_INSN (BB_END (edge_in->src));
1499 bb = create_basic_block (before, NULL, edge_in->src);
1500 BB_COPY_PARTITION (bb, edge_in->src);
1501 }
1502 else
1503 {
1504 bb = create_basic_block (before, NULL, edge_in->dest->prev_bb);
1505 /* ??? Why not edge_in->dest->prev_bb here? */
1506 BB_COPY_PARTITION (bb, edge_in->dest);
1507 }
1508
1509 make_single_succ_edge (bb, edge_in->dest, EDGE_FALLTHRU);
1510
1511 /* For non-fallthru edges, we must adjust the predecessor's
1512 jump instruction to target our new block. */
1513 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
1514 {
1515 edge redirected = redirect_edge_and_branch (edge_in, bb);
1516 gcc_assert (redirected);
1517 }
1518 else
1519 {
1520 if (edge_in->src != ENTRY_BLOCK_PTR)
1521 {
1522 /* For asm goto even splitting of fallthru edge might
1523 need insn patching, as other labels might point to the
1524 old label. */
1525 rtx last = BB_END (edge_in->src);
1526 if (last
1527 && JUMP_P (last)
1528 && edge_in->dest != EXIT_BLOCK_PTR
1529 && extract_asm_operands (PATTERN (last)) != NULL_RTX
1530 && patch_jump_insn (last, before, bb))
1531 df_set_bb_dirty (edge_in->src);
1532 }
1533 redirect_edge_succ (edge_in, bb);
1534 }
1535
1536 return bb;
1537 }
1538
1539 /* Queue instructions for insertion on an edge between two basic blocks.
1540 The new instructions and basic blocks (if any) will not appear in the
1541 CFG until commit_edge_insertions is called. */
1542
1543 void
insert_insn_on_edge(rtx pattern,edge e)1544 insert_insn_on_edge (rtx pattern, edge e)
1545 {
1546 /* We cannot insert instructions on an abnormal critical edge.
1547 It will be easier to find the culprit if we die now. */
1548 gcc_assert (!((e->flags & EDGE_ABNORMAL) && EDGE_CRITICAL_P (e)));
1549
1550 if (e->insns.r == NULL_RTX)
1551 start_sequence ();
1552 else
1553 push_to_sequence (e->insns.r);
1554
1555 emit_insn (pattern);
1556
1557 e->insns.r = get_insns ();
1558 end_sequence ();
1559 }
1560
1561 /* Update the CFG for the instructions queued on edge E. */
1562
1563 void
commit_one_edge_insertion(edge e)1564 commit_one_edge_insertion (edge e)
1565 {
1566 rtx before = NULL_RTX, after = NULL_RTX, insns, tmp, last;
1567 basic_block bb;
1568
1569 /* Pull the insns off the edge now since the edge might go away. */
1570 insns = e->insns.r;
1571 e->insns.r = NULL_RTX;
1572
1573 /* Figure out where to put these insns. If the destination has
1574 one predecessor, insert there. Except for the exit block. */
1575 if (single_pred_p (e->dest) && e->dest != EXIT_BLOCK_PTR)
1576 {
1577 bb = e->dest;
1578
1579 /* Get the location correct wrt a code label, and "nice" wrt
1580 a basic block note, and before everything else. */
1581 tmp = BB_HEAD (bb);
1582 if (LABEL_P (tmp))
1583 tmp = NEXT_INSN (tmp);
1584 if (NOTE_INSN_BASIC_BLOCK_P (tmp))
1585 tmp = NEXT_INSN (tmp);
1586 if (tmp == BB_HEAD (bb))
1587 before = tmp;
1588 else if (tmp)
1589 after = PREV_INSN (tmp);
1590 else
1591 after = get_last_insn ();
1592 }
1593
1594 /* If the source has one successor and the edge is not abnormal,
1595 insert there. Except for the entry block. */
1596 else if ((e->flags & EDGE_ABNORMAL) == 0
1597 && single_succ_p (e->src)
1598 && e->src != ENTRY_BLOCK_PTR)
1599 {
1600 bb = e->src;
1601
1602 /* It is possible to have a non-simple jump here. Consider a target
1603 where some forms of unconditional jumps clobber a register. This
1604 happens on the fr30 for example.
1605
1606 We know this block has a single successor, so we can just emit
1607 the queued insns before the jump. */
1608 if (JUMP_P (BB_END (bb)))
1609 before = BB_END (bb);
1610 else
1611 {
1612 /* We'd better be fallthru, or we've lost track of what's what. */
1613 gcc_assert (e->flags & EDGE_FALLTHRU);
1614
1615 after = BB_END (bb);
1616 }
1617 }
1618
1619 /* Otherwise we must split the edge. */
1620 else
1621 {
1622 bb = split_edge (e);
1623 after = BB_END (bb);
1624
1625 if (flag_reorder_blocks_and_partition
1626 && targetm_common.have_named_sections
1627 && e->src != ENTRY_BLOCK_PTR
1628 && BB_PARTITION (e->src) == BB_COLD_PARTITION
1629 && !(e->flags & EDGE_CROSSING)
1630 && JUMP_P (after)
1631 && !any_condjump_p (after)
1632 && (single_succ_edge (bb)->flags & EDGE_CROSSING))
1633 add_reg_note (after, REG_CROSSING_JUMP, NULL_RTX);
1634 }
1635
1636 /* Now that we've found the spot, do the insertion. */
1637 if (before)
1638 {
1639 emit_insn_before_noloc (insns, before, bb);
1640 last = prev_nonnote_insn (before);
1641 }
1642 else
1643 last = emit_insn_after_noloc (insns, after, bb);
1644
1645 if (returnjump_p (last))
1646 {
1647 /* ??? Remove all outgoing edges from BB and add one for EXIT.
1648 This is not currently a problem because this only happens
1649 for the (single) epilogue, which already has a fallthru edge
1650 to EXIT. */
1651
1652 e = single_succ_edge (bb);
1653 gcc_assert (e->dest == EXIT_BLOCK_PTR
1654 && single_succ_p (bb) && (e->flags & EDGE_FALLTHRU));
1655
1656 e->flags &= ~EDGE_FALLTHRU;
1657 emit_barrier_after (last);
1658
1659 if (before)
1660 delete_insn (before);
1661 }
1662 else
1663 gcc_assert (!JUMP_P (last));
1664 }
1665
1666 /* Update the CFG for all queued instructions. */
1667
1668 void
commit_edge_insertions(void)1669 commit_edge_insertions (void)
1670 {
1671 basic_block bb;
1672
1673 #ifdef ENABLE_CHECKING
1674 verify_flow_info ();
1675 #endif
1676
1677 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb)
1678 {
1679 edge e;
1680 edge_iterator ei;
1681
1682 FOR_EACH_EDGE (e, ei, bb->succs)
1683 if (e->insns.r)
1684 commit_one_edge_insertion (e);
1685 }
1686 }
1687
1688
1689 /* Print out RTL-specific basic block information (live information
1690 at start and end). */
1691
1692 static void
rtl_dump_bb(basic_block bb,FILE * outf,int indent,int flags ATTRIBUTE_UNUSED)1693 rtl_dump_bb (basic_block bb, FILE *outf, int indent, int flags ATTRIBUTE_UNUSED)
1694 {
1695 rtx insn;
1696 rtx last;
1697 char *s_indent;
1698
1699 s_indent = (char *) alloca ((size_t) indent + 1);
1700 memset (s_indent, ' ', (size_t) indent);
1701 s_indent[indent] = '\0';
1702
1703 if (df)
1704 {
1705 df_dump_top (bb, outf);
1706 putc ('\n', outf);
1707 }
1708
1709 if (bb->index != ENTRY_BLOCK && bb->index != EXIT_BLOCK)
1710 for (insn = BB_HEAD (bb), last = NEXT_INSN (BB_END (bb)); insn != last;
1711 insn = NEXT_INSN (insn))
1712 print_rtl_single (outf, insn);
1713
1714 if (df)
1715 {
1716 df_dump_bottom (bb, outf);
1717 putc ('\n', outf);
1718 }
1719
1720 }
1721
1722 /* Like print_rtl, but also print out live information for the start of each
1723 basic block. */
1724
1725 void
print_rtl_with_bb(FILE * outf,const_rtx rtx_first)1726 print_rtl_with_bb (FILE *outf, const_rtx rtx_first)
1727 {
1728 const_rtx tmp_rtx;
1729 if (rtx_first == 0)
1730 fprintf (outf, "(nil)\n");
1731 else
1732 {
1733 enum bb_state { NOT_IN_BB, IN_ONE_BB, IN_MULTIPLE_BB };
1734 int max_uid = get_max_uid ();
1735 basic_block *start = XCNEWVEC (basic_block, max_uid);
1736 basic_block *end = XCNEWVEC (basic_block, max_uid);
1737 enum bb_state *in_bb_p = XCNEWVEC (enum bb_state, max_uid);
1738
1739 basic_block bb;
1740
1741 if (df)
1742 df_dump_start (outf);
1743
1744 FOR_EACH_BB_REVERSE (bb)
1745 {
1746 rtx x;
1747
1748 start[INSN_UID (BB_HEAD (bb))] = bb;
1749 end[INSN_UID (BB_END (bb))] = bb;
1750 for (x = BB_HEAD (bb); x != NULL_RTX; x = NEXT_INSN (x))
1751 {
1752 enum bb_state state = IN_MULTIPLE_BB;
1753
1754 if (in_bb_p[INSN_UID (x)] == NOT_IN_BB)
1755 state = IN_ONE_BB;
1756 in_bb_p[INSN_UID (x)] = state;
1757
1758 if (x == BB_END (bb))
1759 break;
1760 }
1761 }
1762
1763 for (tmp_rtx = rtx_first; NULL != tmp_rtx; tmp_rtx = NEXT_INSN (tmp_rtx))
1764 {
1765 int did_output;
1766
1767 bb = start[INSN_UID (tmp_rtx)];
1768 if (bb != NULL)
1769 dump_bb_info (bb, true, false, dump_flags, ";; ", outf);
1770
1771 if (in_bb_p[INSN_UID (tmp_rtx)] == NOT_IN_BB
1772 && !NOTE_P (tmp_rtx)
1773 && !BARRIER_P (tmp_rtx))
1774 fprintf (outf, ";; Insn is not within a basic block\n");
1775 else if (in_bb_p[INSN_UID (tmp_rtx)] == IN_MULTIPLE_BB)
1776 fprintf (outf, ";; Insn is in multiple basic blocks\n");
1777
1778 did_output = print_rtl_single (outf, tmp_rtx);
1779
1780 bb = end[INSN_UID (tmp_rtx)];
1781 if (bb != NULL)
1782 dump_bb_info (bb, false, true, dump_flags, ";; ", outf);
1783 if (did_output)
1784 putc ('\n', outf);
1785 }
1786
1787 free (start);
1788 free (end);
1789 free (in_bb_p);
1790 }
1791
1792 if (crtl->epilogue_delay_list != 0)
1793 {
1794 fprintf (outf, "\n;; Insns in epilogue delay list:\n\n");
1795 for (tmp_rtx = crtl->epilogue_delay_list; tmp_rtx != 0;
1796 tmp_rtx = XEXP (tmp_rtx, 1))
1797 print_rtl_single (outf, XEXP (tmp_rtx, 0));
1798 }
1799 }
1800
1801 void
update_br_prob_note(basic_block bb)1802 update_br_prob_note (basic_block bb)
1803 {
1804 rtx note;
1805 if (!JUMP_P (BB_END (bb)))
1806 return;
1807 note = find_reg_note (BB_END (bb), REG_BR_PROB, NULL_RTX);
1808 if (!note || INTVAL (XEXP (note, 0)) == BRANCH_EDGE (bb)->probability)
1809 return;
1810 XEXP (note, 0) = GEN_INT (BRANCH_EDGE (bb)->probability);
1811 }
1812
1813 /* Get the last insn associated with block BB (that includes barriers and
1814 tablejumps after BB). */
1815 rtx
get_last_bb_insn(basic_block bb)1816 get_last_bb_insn (basic_block bb)
1817 {
1818 rtx tmp;
1819 rtx end = BB_END (bb);
1820
1821 /* Include any jump table following the basic block. */
1822 if (tablejump_p (end, NULL, &tmp))
1823 end = tmp;
1824
1825 /* Include any barriers that may follow the basic block. */
1826 tmp = next_nonnote_insn_bb (end);
1827 while (tmp && BARRIER_P (tmp))
1828 {
1829 end = tmp;
1830 tmp = next_nonnote_insn_bb (end);
1831 }
1832
1833 return end;
1834 }
1835
1836 /* Verify the CFG and RTL consistency common for both underlying RTL and
1837 cfglayout RTL.
1838
1839 Currently it does following checks:
1840
1841 - overlapping of basic blocks
1842 - insns with wrong BLOCK_FOR_INSN pointers
1843 - headers of basic blocks (the NOTE_INSN_BASIC_BLOCK note)
1844 - tails of basic blocks (ensure that boundary is necessary)
1845 - scans body of the basic block for JUMP_INSN, CODE_LABEL
1846 and NOTE_INSN_BASIC_BLOCK
1847 - verify that no fall_thru edge crosses hot/cold partition boundaries
1848 - verify that there are no pending RTL branch predictions
1849
1850 In future it can be extended check a lot of other stuff as well
1851 (reachability of basic blocks, life information, etc. etc.). */
1852
1853 static int
rtl_verify_flow_info_1(void)1854 rtl_verify_flow_info_1 (void)
1855 {
1856 rtx x;
1857 int err = 0;
1858 basic_block bb;
1859
1860 /* Check the general integrity of the basic blocks. */
1861 FOR_EACH_BB_REVERSE (bb)
1862 {
1863 rtx insn;
1864
1865 if (!(bb->flags & BB_RTL))
1866 {
1867 error ("BB_RTL flag not set for block %d", bb->index);
1868 err = 1;
1869 }
1870
1871 FOR_BB_INSNS (bb, insn)
1872 if (BLOCK_FOR_INSN (insn) != bb)
1873 {
1874 error ("insn %d basic block pointer is %d, should be %d",
1875 INSN_UID (insn),
1876 BLOCK_FOR_INSN (insn) ? BLOCK_FOR_INSN (insn)->index : 0,
1877 bb->index);
1878 err = 1;
1879 }
1880
1881 for (insn = bb->il.rtl->header; insn; insn = NEXT_INSN (insn))
1882 if (!BARRIER_P (insn)
1883 && BLOCK_FOR_INSN (insn) != NULL)
1884 {
1885 error ("insn %d in header of bb %d has non-NULL basic block",
1886 INSN_UID (insn), bb->index);
1887 err = 1;
1888 }
1889 for (insn = bb->il.rtl->footer; insn; insn = NEXT_INSN (insn))
1890 if (!BARRIER_P (insn)
1891 && BLOCK_FOR_INSN (insn) != NULL)
1892 {
1893 error ("insn %d in footer of bb %d has non-NULL basic block",
1894 INSN_UID (insn), bb->index);
1895 err = 1;
1896 }
1897 }
1898
1899 /* Now check the basic blocks (boundaries etc.) */
1900 FOR_EACH_BB_REVERSE (bb)
1901 {
1902 int n_fallthru = 0, n_eh = 0, n_call = 0, n_abnormal = 0, n_branch = 0;
1903 edge e, fallthru = NULL;
1904 rtx note;
1905 edge_iterator ei;
1906
1907 if (JUMP_P (BB_END (bb))
1908 && (note = find_reg_note (BB_END (bb), REG_BR_PROB, NULL_RTX))
1909 && EDGE_COUNT (bb->succs) >= 2
1910 && any_condjump_p (BB_END (bb)))
1911 {
1912 if (INTVAL (XEXP (note, 0)) != BRANCH_EDGE (bb)->probability
1913 && profile_status != PROFILE_ABSENT)
1914 {
1915 error ("verify_flow_info: REG_BR_PROB does not match cfg %wi %i",
1916 INTVAL (XEXP (note, 0)), BRANCH_EDGE (bb)->probability);
1917 err = 1;
1918 }
1919 }
1920 FOR_EACH_EDGE (e, ei, bb->succs)
1921 {
1922 bool is_crossing;
1923
1924 if (e->flags & EDGE_FALLTHRU)
1925 n_fallthru++, fallthru = e;
1926
1927 is_crossing = (BB_PARTITION (e->src) != BB_PARTITION (e->dest)
1928 && e->src != ENTRY_BLOCK_PTR
1929 && e->dest != EXIT_BLOCK_PTR);
1930 if (e->flags & EDGE_CROSSING)
1931 {
1932 if (!is_crossing)
1933 {
1934 error ("EDGE_CROSSING incorrectly set across same section");
1935 err = 1;
1936 }
1937 if (e->flags & EDGE_FALLTHRU)
1938 {
1939 error ("fallthru edge crosses section boundary (bb %i)",
1940 e->src->index);
1941 err = 1;
1942 }
1943 if (e->flags & EDGE_EH)
1944 {
1945 error ("EH edge crosses section boundary (bb %i)",
1946 e->src->index);
1947 err = 1;
1948 }
1949 }
1950 else if (is_crossing)
1951 {
1952 error ("EDGE_CROSSING missing across section boundary");
1953 err = 1;
1954 }
1955
1956 if ((e->flags & ~(EDGE_DFS_BACK
1957 | EDGE_CAN_FALLTHRU
1958 | EDGE_IRREDUCIBLE_LOOP
1959 | EDGE_LOOP_EXIT
1960 | EDGE_CROSSING
1961 | EDGE_PRESERVE)) == 0)
1962 n_branch++;
1963
1964 if (e->flags & EDGE_ABNORMAL_CALL)
1965 n_call++;
1966
1967 if (e->flags & EDGE_EH)
1968 n_eh++;
1969 else if (e->flags & EDGE_ABNORMAL)
1970 n_abnormal++;
1971 }
1972
1973 if (n_eh && !find_reg_note (BB_END (bb), REG_EH_REGION, NULL_RTX))
1974 {
1975 error ("missing REG_EH_REGION note in the end of bb %i", bb->index);
1976 err = 1;
1977 }
1978 if (n_eh > 1)
1979 {
1980 error ("too many eh edges %i", bb->index);
1981 err = 1;
1982 }
1983 if (n_branch
1984 && (!JUMP_P (BB_END (bb))
1985 || (n_branch > 1 && (any_uncondjump_p (BB_END (bb))
1986 || any_condjump_p (BB_END (bb))))))
1987 {
1988 error ("too many outgoing branch edges from bb %i", bb->index);
1989 err = 1;
1990 }
1991 if (n_fallthru && any_uncondjump_p (BB_END (bb)))
1992 {
1993 error ("fallthru edge after unconditional jump %i", bb->index);
1994 err = 1;
1995 }
1996 if (n_branch != 1 && any_uncondjump_p (BB_END (bb)))
1997 {
1998 error ("wrong number of branch edges after unconditional jump %i",
1999 bb->index);
2000 err = 1;
2001 }
2002 if (n_branch != 1 && any_condjump_p (BB_END (bb))
2003 && JUMP_LABEL (BB_END (bb)) != BB_HEAD (fallthru->dest))
2004 {
2005 error ("wrong amount of branch edges after conditional jump %i",
2006 bb->index);
2007 err = 1;
2008 }
2009 if (n_call && !CALL_P (BB_END (bb)))
2010 {
2011 error ("call edges for non-call insn in bb %i", bb->index);
2012 err = 1;
2013 }
2014 if (n_abnormal
2015 && (!CALL_P (BB_END (bb)) && n_call != n_abnormal)
2016 && (!JUMP_P (BB_END (bb))
2017 || any_condjump_p (BB_END (bb))
2018 || any_uncondjump_p (BB_END (bb))))
2019 {
2020 error ("abnormal edges for no purpose in bb %i", bb->index);
2021 err = 1;
2022 }
2023
2024 for (x = BB_HEAD (bb); x != NEXT_INSN (BB_END (bb)); x = NEXT_INSN (x))
2025 /* We may have a barrier inside a basic block before dead code
2026 elimination. There is no BLOCK_FOR_INSN field in a barrier. */
2027 if (!BARRIER_P (x) && BLOCK_FOR_INSN (x) != bb)
2028 {
2029 debug_rtx (x);
2030 if (! BLOCK_FOR_INSN (x))
2031 error
2032 ("insn %d inside basic block %d but block_for_insn is NULL",
2033 INSN_UID (x), bb->index);
2034 else
2035 error
2036 ("insn %d inside basic block %d but block_for_insn is %i",
2037 INSN_UID (x), bb->index, BLOCK_FOR_INSN (x)->index);
2038
2039 err = 1;
2040 }
2041
2042 /* OK pointers are correct. Now check the header of basic
2043 block. It ought to contain optional CODE_LABEL followed
2044 by NOTE_BASIC_BLOCK. */
2045 x = BB_HEAD (bb);
2046 if (LABEL_P (x))
2047 {
2048 if (BB_END (bb) == x)
2049 {
2050 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
2051 bb->index);
2052 err = 1;
2053 }
2054
2055 x = NEXT_INSN (x);
2056 }
2057
2058 if (!NOTE_INSN_BASIC_BLOCK_P (x) || NOTE_BASIC_BLOCK (x) != bb)
2059 {
2060 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
2061 bb->index);
2062 err = 1;
2063 }
2064
2065 if (BB_END (bb) == x)
2066 /* Do checks for empty blocks here. */
2067 ;
2068 else
2069 for (x = NEXT_INSN (x); x; x = NEXT_INSN (x))
2070 {
2071 if (NOTE_INSN_BASIC_BLOCK_P (x))
2072 {
2073 error ("NOTE_INSN_BASIC_BLOCK %d in middle of basic block %d",
2074 INSN_UID (x), bb->index);
2075 err = 1;
2076 }
2077
2078 if (x == BB_END (bb))
2079 break;
2080
2081 if (control_flow_insn_p (x))
2082 {
2083 error ("in basic block %d:", bb->index);
2084 fatal_insn ("flow control insn inside a basic block", x);
2085 }
2086 }
2087 }
2088
2089 /* Clean up. */
2090 return err;
2091 }
2092
2093 /* Verify the CFG and RTL consistency common for both underlying RTL and
2094 cfglayout RTL.
2095
2096 Currently it does following checks:
2097 - all checks of rtl_verify_flow_info_1
2098 - test head/end pointers
2099 - check that all insns are in the basic blocks
2100 (except the switch handling code, barriers and notes)
2101 - check that all returns are followed by barriers
2102 - check that all fallthru edge points to the adjacent blocks. */
2103
2104 static int
rtl_verify_flow_info(void)2105 rtl_verify_flow_info (void)
2106 {
2107 basic_block bb;
2108 int err = rtl_verify_flow_info_1 ();
2109 rtx x;
2110 rtx last_head = get_last_insn ();
2111 basic_block *bb_info;
2112 int num_bb_notes;
2113 const rtx rtx_first = get_insns ();
2114 basic_block last_bb_seen = ENTRY_BLOCK_PTR, curr_bb = NULL;
2115 const int max_uid = get_max_uid ();
2116
2117 bb_info = XCNEWVEC (basic_block, max_uid);
2118
2119 FOR_EACH_BB_REVERSE (bb)
2120 {
2121 edge e;
2122 rtx head = BB_HEAD (bb);
2123 rtx end = BB_END (bb);
2124
2125 for (x = last_head; x != NULL_RTX; x = PREV_INSN (x))
2126 {
2127 /* Verify the end of the basic block is in the INSN chain. */
2128 if (x == end)
2129 break;
2130
2131 /* And that the code outside of basic blocks has NULL bb field. */
2132 if (!BARRIER_P (x)
2133 && BLOCK_FOR_INSN (x) != NULL)
2134 {
2135 error ("insn %d outside of basic blocks has non-NULL bb field",
2136 INSN_UID (x));
2137 err = 1;
2138 }
2139 }
2140
2141 if (!x)
2142 {
2143 error ("end insn %d for block %d not found in the insn stream",
2144 INSN_UID (end), bb->index);
2145 err = 1;
2146 }
2147
2148 /* Work backwards from the end to the head of the basic block
2149 to verify the head is in the RTL chain. */
2150 for (; x != NULL_RTX; x = PREV_INSN (x))
2151 {
2152 /* While walking over the insn chain, verify insns appear
2153 in only one basic block. */
2154 if (bb_info[INSN_UID (x)] != NULL)
2155 {
2156 error ("insn %d is in multiple basic blocks (%d and %d)",
2157 INSN_UID (x), bb->index, bb_info[INSN_UID (x)]->index);
2158 err = 1;
2159 }
2160
2161 bb_info[INSN_UID (x)] = bb;
2162
2163 if (x == head)
2164 break;
2165 }
2166 if (!x)
2167 {
2168 error ("head insn %d for block %d not found in the insn stream",
2169 INSN_UID (head), bb->index);
2170 err = 1;
2171 }
2172
2173 last_head = PREV_INSN (x);
2174
2175 e = find_fallthru_edge (bb->succs);
2176 if (!e)
2177 {
2178 rtx insn;
2179
2180 /* Ensure existence of barrier in BB with no fallthru edges. */
2181 for (insn = NEXT_INSN (BB_END (bb)); ; insn = NEXT_INSN (insn))
2182 {
2183 if (!insn || NOTE_INSN_BASIC_BLOCK_P (insn))
2184 {
2185 error ("missing barrier after block %i", bb->index);
2186 err = 1;
2187 break;
2188 }
2189 if (BARRIER_P (insn))
2190 break;
2191 }
2192 }
2193 else if (e->src != ENTRY_BLOCK_PTR
2194 && e->dest != EXIT_BLOCK_PTR)
2195 {
2196 rtx insn;
2197
2198 if (e->src->next_bb != e->dest)
2199 {
2200 error
2201 ("verify_flow_info: Incorrect blocks for fallthru %i->%i",
2202 e->src->index, e->dest->index);
2203 err = 1;
2204 }
2205 else
2206 for (insn = NEXT_INSN (BB_END (e->src)); insn != BB_HEAD (e->dest);
2207 insn = NEXT_INSN (insn))
2208 if (BARRIER_P (insn) || INSN_P (insn))
2209 {
2210 error ("verify_flow_info: Incorrect fallthru %i->%i",
2211 e->src->index, e->dest->index);
2212 fatal_insn ("wrong insn in the fallthru edge", insn);
2213 err = 1;
2214 }
2215 }
2216 }
2217
2218 for (x = last_head; x != NULL_RTX; x = PREV_INSN (x))
2219 {
2220 /* Check that the code before the first basic block has NULL
2221 bb field. */
2222 if (!BARRIER_P (x)
2223 && BLOCK_FOR_INSN (x) != NULL)
2224 {
2225 error ("insn %d outside of basic blocks has non-NULL bb field",
2226 INSN_UID (x));
2227 err = 1;
2228 }
2229 }
2230 free (bb_info);
2231
2232 num_bb_notes = 0;
2233 last_bb_seen = ENTRY_BLOCK_PTR;
2234
2235 for (x = rtx_first; x; x = NEXT_INSN (x))
2236 {
2237 if (NOTE_INSN_BASIC_BLOCK_P (x))
2238 {
2239 bb = NOTE_BASIC_BLOCK (x);
2240
2241 num_bb_notes++;
2242 if (bb != last_bb_seen->next_bb)
2243 internal_error ("basic blocks not laid down consecutively");
2244
2245 curr_bb = last_bb_seen = bb;
2246 }
2247
2248 if (!curr_bb)
2249 {
2250 switch (GET_CODE (x))
2251 {
2252 case BARRIER:
2253 case NOTE:
2254 break;
2255
2256 case CODE_LABEL:
2257 /* An addr_vec is placed outside any basic block. */
2258 if (NEXT_INSN (x)
2259 && JUMP_TABLE_DATA_P (NEXT_INSN (x)))
2260 x = NEXT_INSN (x);
2261
2262 /* But in any case, non-deletable labels can appear anywhere. */
2263 break;
2264
2265 default:
2266 fatal_insn ("insn outside basic block", x);
2267 }
2268 }
2269
2270 if (JUMP_P (x)
2271 && returnjump_p (x) && ! condjump_p (x)
2272 && ! (next_nonnote_insn (x) && BARRIER_P (next_nonnote_insn (x))))
2273 fatal_insn ("return not followed by barrier", x);
2274 if (curr_bb && x == BB_END (curr_bb))
2275 curr_bb = NULL;
2276 }
2277
2278 if (num_bb_notes != n_basic_blocks - NUM_FIXED_BLOCKS)
2279 internal_error
2280 ("number of bb notes in insn chain (%d) != n_basic_blocks (%d)",
2281 num_bb_notes, n_basic_blocks);
2282
2283 return err;
2284 }
2285
2286 /* Assume that the preceding pass has possibly eliminated jump instructions
2287 or converted the unconditional jumps. Eliminate the edges from CFG.
2288 Return true if any edges are eliminated. */
2289
2290 bool
purge_dead_edges(basic_block bb)2291 purge_dead_edges (basic_block bb)
2292 {
2293 edge e;
2294 rtx insn = BB_END (bb), note;
2295 bool purged = false;
2296 bool found;
2297 edge_iterator ei;
2298
2299 if (DEBUG_INSN_P (insn) && insn != BB_HEAD (bb))
2300 do
2301 insn = PREV_INSN (insn);
2302 while ((DEBUG_INSN_P (insn) || NOTE_P (insn)) && insn != BB_HEAD (bb));
2303
2304 /* If this instruction cannot trap, remove REG_EH_REGION notes. */
2305 if (NONJUMP_INSN_P (insn)
2306 && (note = find_reg_note (insn, REG_EH_REGION, NULL)))
2307 {
2308 rtx eqnote;
2309
2310 if (! may_trap_p (PATTERN (insn))
2311 || ((eqnote = find_reg_equal_equiv_note (insn))
2312 && ! may_trap_p (XEXP (eqnote, 0))))
2313 remove_note (insn, note);
2314 }
2315
2316 /* Cleanup abnormal edges caused by exceptions or non-local gotos. */
2317 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2318 {
2319 bool remove = false;
2320
2321 /* There are three types of edges we need to handle correctly here: EH
2322 edges, abnormal call EH edges, and abnormal call non-EH edges. The
2323 latter can appear when nonlocal gotos are used. */
2324 if (e->flags & EDGE_ABNORMAL_CALL)
2325 {
2326 if (!CALL_P (insn))
2327 remove = true;
2328 else if (can_nonlocal_goto (insn))
2329 ;
2330 else if ((e->flags & EDGE_EH) && can_throw_internal (insn))
2331 ;
2332 else if (flag_tm && find_reg_note (insn, REG_TM, NULL))
2333 ;
2334 else
2335 remove = true;
2336 }
2337 else if (e->flags & EDGE_EH)
2338 remove = !can_throw_internal (insn);
2339
2340 if (remove)
2341 {
2342 remove_edge (e);
2343 df_set_bb_dirty (bb);
2344 purged = true;
2345 }
2346 else
2347 ei_next (&ei);
2348 }
2349
2350 if (JUMP_P (insn))
2351 {
2352 rtx note;
2353 edge b,f;
2354 edge_iterator ei;
2355
2356 /* We do care only about conditional jumps and simplejumps. */
2357 if (!any_condjump_p (insn)
2358 && !returnjump_p (insn)
2359 && !simplejump_p (insn))
2360 return purged;
2361
2362 /* Branch probability/prediction notes are defined only for
2363 condjumps. We've possibly turned condjump into simplejump. */
2364 if (simplejump_p (insn))
2365 {
2366 note = find_reg_note (insn, REG_BR_PROB, NULL);
2367 if (note)
2368 remove_note (insn, note);
2369 while ((note = find_reg_note (insn, REG_BR_PRED, NULL)))
2370 remove_note (insn, note);
2371 }
2372
2373 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2374 {
2375 /* Avoid abnormal flags to leak from computed jumps turned
2376 into simplejumps. */
2377
2378 e->flags &= ~EDGE_ABNORMAL;
2379
2380 /* See if this edge is one we should keep. */
2381 if ((e->flags & EDGE_FALLTHRU) && any_condjump_p (insn))
2382 /* A conditional jump can fall through into the next
2383 block, so we should keep the edge. */
2384 {
2385 ei_next (&ei);
2386 continue;
2387 }
2388 else if (e->dest != EXIT_BLOCK_PTR
2389 && BB_HEAD (e->dest) == JUMP_LABEL (insn))
2390 /* If the destination block is the target of the jump,
2391 keep the edge. */
2392 {
2393 ei_next (&ei);
2394 continue;
2395 }
2396 else if (e->dest == EXIT_BLOCK_PTR && returnjump_p (insn))
2397 /* If the destination block is the exit block, and this
2398 instruction is a return, then keep the edge. */
2399 {
2400 ei_next (&ei);
2401 continue;
2402 }
2403 else if ((e->flags & EDGE_EH) && can_throw_internal (insn))
2404 /* Keep the edges that correspond to exceptions thrown by
2405 this instruction and rematerialize the EDGE_ABNORMAL
2406 flag we just cleared above. */
2407 {
2408 e->flags |= EDGE_ABNORMAL;
2409 ei_next (&ei);
2410 continue;
2411 }
2412
2413 /* We do not need this edge. */
2414 df_set_bb_dirty (bb);
2415 purged = true;
2416 remove_edge (e);
2417 }
2418
2419 if (EDGE_COUNT (bb->succs) == 0 || !purged)
2420 return purged;
2421
2422 if (dump_file)
2423 fprintf (dump_file, "Purged edges from bb %i\n", bb->index);
2424
2425 if (!optimize)
2426 return purged;
2427
2428 /* Redistribute probabilities. */
2429 if (single_succ_p (bb))
2430 {
2431 single_succ_edge (bb)->probability = REG_BR_PROB_BASE;
2432 single_succ_edge (bb)->count = bb->count;
2433 }
2434 else
2435 {
2436 note = find_reg_note (insn, REG_BR_PROB, NULL);
2437 if (!note)
2438 return purged;
2439
2440 b = BRANCH_EDGE (bb);
2441 f = FALLTHRU_EDGE (bb);
2442 b->probability = INTVAL (XEXP (note, 0));
2443 f->probability = REG_BR_PROB_BASE - b->probability;
2444 b->count = bb->count * b->probability / REG_BR_PROB_BASE;
2445 f->count = bb->count * f->probability / REG_BR_PROB_BASE;
2446 }
2447
2448 return purged;
2449 }
2450 else if (CALL_P (insn) && SIBLING_CALL_P (insn))
2451 {
2452 /* First, there should not be any EH or ABCALL edges resulting
2453 from non-local gotos and the like. If there were, we shouldn't
2454 have created the sibcall in the first place. Second, there
2455 should of course never have been a fallthru edge. */
2456 gcc_assert (single_succ_p (bb));
2457 gcc_assert (single_succ_edge (bb)->flags
2458 == (EDGE_SIBCALL | EDGE_ABNORMAL));
2459
2460 return 0;
2461 }
2462
2463 /* If we don't see a jump insn, we don't know exactly why the block would
2464 have been broken at this point. Look for a simple, non-fallthru edge,
2465 as these are only created by conditional branches. If we find such an
2466 edge we know that there used to be a jump here and can then safely
2467 remove all non-fallthru edges. */
2468 found = false;
2469 FOR_EACH_EDGE (e, ei, bb->succs)
2470 if (! (e->flags & (EDGE_COMPLEX | EDGE_FALLTHRU)))
2471 {
2472 found = true;
2473 break;
2474 }
2475
2476 if (!found)
2477 return purged;
2478
2479 /* Remove all but the fake and fallthru edges. The fake edge may be
2480 the only successor for this block in the case of noreturn
2481 calls. */
2482 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2483 {
2484 if (!(e->flags & (EDGE_FALLTHRU | EDGE_FAKE)))
2485 {
2486 df_set_bb_dirty (bb);
2487 remove_edge (e);
2488 purged = true;
2489 }
2490 else
2491 ei_next (&ei);
2492 }
2493
2494 gcc_assert (single_succ_p (bb));
2495
2496 single_succ_edge (bb)->probability = REG_BR_PROB_BASE;
2497 single_succ_edge (bb)->count = bb->count;
2498
2499 if (dump_file)
2500 fprintf (dump_file, "Purged non-fallthru edges from bb %i\n",
2501 bb->index);
2502 return purged;
2503 }
2504
2505 /* Search all basic blocks for potentially dead edges and purge them. Return
2506 true if some edge has been eliminated. */
2507
2508 bool
purge_all_dead_edges(void)2509 purge_all_dead_edges (void)
2510 {
2511 int purged = false;
2512 basic_block bb;
2513
2514 FOR_EACH_BB (bb)
2515 {
2516 bool purged_here = purge_dead_edges (bb);
2517
2518 purged |= purged_here;
2519 }
2520
2521 return purged;
2522 }
2523
2524 /* This is used by a few passes that emit some instructions after abnormal
2525 calls, moving the basic block's end, while they in fact do want to emit
2526 them on the fallthru edge. Look for abnormal call edges, find backward
2527 the call in the block and insert the instructions on the edge instead.
2528
2529 Similarly, handle instructions throwing exceptions internally.
2530
2531 Return true when instructions have been found and inserted on edges. */
2532
2533 bool
fixup_abnormal_edges(void)2534 fixup_abnormal_edges (void)
2535 {
2536 bool inserted = false;
2537 basic_block bb;
2538
2539 FOR_EACH_BB (bb)
2540 {
2541 edge e;
2542 edge_iterator ei;
2543
2544 /* Look for cases we are interested in - calls or instructions causing
2545 exceptions. */
2546 FOR_EACH_EDGE (e, ei, bb->succs)
2547 if ((e->flags & EDGE_ABNORMAL_CALL)
2548 || ((e->flags & (EDGE_ABNORMAL | EDGE_EH))
2549 == (EDGE_ABNORMAL | EDGE_EH)))
2550 break;
2551
2552 if (e && !CALL_P (BB_END (bb)) && !can_throw_internal (BB_END (bb)))
2553 {
2554 rtx insn;
2555
2556 /* Get past the new insns generated. Allow notes, as the insns
2557 may be already deleted. */
2558 insn = BB_END (bb);
2559 while ((NONJUMP_INSN_P (insn) || NOTE_P (insn))
2560 && !can_throw_internal (insn)
2561 && insn != BB_HEAD (bb))
2562 insn = PREV_INSN (insn);
2563
2564 if (CALL_P (insn) || can_throw_internal (insn))
2565 {
2566 rtx stop, next;
2567
2568 e = find_fallthru_edge (bb->succs);
2569
2570 stop = NEXT_INSN (BB_END (bb));
2571 BB_END (bb) = insn;
2572
2573 for (insn = NEXT_INSN (insn); insn != stop; insn = next)
2574 {
2575 next = NEXT_INSN (insn);
2576 if (INSN_P (insn))
2577 {
2578 delete_insn (insn);
2579
2580 /* Sometimes there's still the return value USE.
2581 If it's placed after a trapping call (i.e. that
2582 call is the last insn anyway), we have no fallthru
2583 edge. Simply delete this use and don't try to insert
2584 on the non-existent edge. */
2585 if (GET_CODE (PATTERN (insn)) != USE)
2586 {
2587 /* We're not deleting it, we're moving it. */
2588 INSN_DELETED_P (insn) = 0;
2589 PREV_INSN (insn) = NULL_RTX;
2590 NEXT_INSN (insn) = NULL_RTX;
2591
2592 insert_insn_on_edge (insn, e);
2593 inserted = true;
2594 }
2595 }
2596 else if (!BARRIER_P (insn))
2597 set_block_for_insn (insn, NULL);
2598 }
2599 }
2600
2601 /* It may be that we don't find any trapping insn. In this
2602 case we discovered quite late that the insn that had been
2603 marked as can_throw_internal in fact couldn't trap at all.
2604 So we should in fact delete the EH edges out of the block. */
2605 else
2606 purge_dead_edges (bb);
2607 }
2608 }
2609
2610 return inserted;
2611 }
2612
2613 /* Same as split_block but update cfg_layout structures. */
2614
2615 static basic_block
cfg_layout_split_block(basic_block bb,void * insnp)2616 cfg_layout_split_block (basic_block bb, void *insnp)
2617 {
2618 rtx insn = (rtx) insnp;
2619 basic_block new_bb = rtl_split_block (bb, insn);
2620
2621 new_bb->il.rtl->footer = bb->il.rtl->footer;
2622 bb->il.rtl->footer = NULL;
2623
2624 return new_bb;
2625 }
2626
2627 /* Redirect Edge to DEST. */
2628 static edge
cfg_layout_redirect_edge_and_branch(edge e,basic_block dest)2629 cfg_layout_redirect_edge_and_branch (edge e, basic_block dest)
2630 {
2631 basic_block src = e->src;
2632 edge ret;
2633
2634 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
2635 return NULL;
2636
2637 if (e->dest == dest)
2638 return e;
2639
2640 if (e->src != ENTRY_BLOCK_PTR
2641 && (ret = try_redirect_by_replacing_jump (e, dest, true)))
2642 {
2643 df_set_bb_dirty (src);
2644 return ret;
2645 }
2646
2647 if (e->src == ENTRY_BLOCK_PTR
2648 && (e->flags & EDGE_FALLTHRU) && !(e->flags & EDGE_COMPLEX))
2649 {
2650 if (dump_file)
2651 fprintf (dump_file, "Redirecting entry edge from bb %i to %i\n",
2652 e->src->index, dest->index);
2653
2654 df_set_bb_dirty (e->src);
2655 redirect_edge_succ (e, dest);
2656 return e;
2657 }
2658
2659 /* Redirect_edge_and_branch may decide to turn branch into fallthru edge
2660 in the case the basic block appears to be in sequence. Avoid this
2661 transformation. */
2662
2663 if (e->flags & EDGE_FALLTHRU)
2664 {
2665 /* Redirect any branch edges unified with the fallthru one. */
2666 if (JUMP_P (BB_END (src))
2667 && label_is_jump_target_p (BB_HEAD (e->dest),
2668 BB_END (src)))
2669 {
2670 edge redirected;
2671
2672 if (dump_file)
2673 fprintf (dump_file, "Fallthru edge unified with branch "
2674 "%i->%i redirected to %i\n",
2675 e->src->index, e->dest->index, dest->index);
2676 e->flags &= ~EDGE_FALLTHRU;
2677 redirected = redirect_branch_edge (e, dest);
2678 gcc_assert (redirected);
2679 redirected->flags |= EDGE_FALLTHRU;
2680 df_set_bb_dirty (redirected->src);
2681 return redirected;
2682 }
2683 /* In case we are redirecting fallthru edge to the branch edge
2684 of conditional jump, remove it. */
2685 if (EDGE_COUNT (src->succs) == 2)
2686 {
2687 /* Find the edge that is different from E. */
2688 edge s = EDGE_SUCC (src, EDGE_SUCC (src, 0) == e);
2689
2690 if (s->dest == dest
2691 && any_condjump_p (BB_END (src))
2692 && onlyjump_p (BB_END (src)))
2693 delete_insn (BB_END (src));
2694 }
2695 if (dump_file)
2696 fprintf (dump_file, "Redirecting fallthru edge %i->%i to %i\n",
2697 e->src->index, e->dest->index, dest->index);
2698 ret = redirect_edge_succ_nodup (e, dest);
2699 }
2700 else
2701 ret = redirect_branch_edge (e, dest);
2702
2703 /* We don't want simplejumps in the insn stream during cfglayout. */
2704 gcc_assert (!simplejump_p (BB_END (src)));
2705
2706 df_set_bb_dirty (src);
2707 return ret;
2708 }
2709
2710 /* Simple wrapper as we always can redirect fallthru edges. */
2711 static basic_block
cfg_layout_redirect_edge_and_branch_force(edge e,basic_block dest)2712 cfg_layout_redirect_edge_and_branch_force (edge e, basic_block dest)
2713 {
2714 edge redirected = cfg_layout_redirect_edge_and_branch (e, dest);
2715
2716 gcc_assert (redirected);
2717 return NULL;
2718 }
2719
2720 /* Same as delete_basic_block but update cfg_layout structures. */
2721
2722 static void
cfg_layout_delete_block(basic_block bb)2723 cfg_layout_delete_block (basic_block bb)
2724 {
2725 rtx insn, next, prev = PREV_INSN (BB_HEAD (bb)), *to, remaints;
2726
2727 if (bb->il.rtl->header)
2728 {
2729 next = BB_HEAD (bb);
2730 if (prev)
2731 NEXT_INSN (prev) = bb->il.rtl->header;
2732 else
2733 set_first_insn (bb->il.rtl->header);
2734 PREV_INSN (bb->il.rtl->header) = prev;
2735 insn = bb->il.rtl->header;
2736 while (NEXT_INSN (insn))
2737 insn = NEXT_INSN (insn);
2738 NEXT_INSN (insn) = next;
2739 PREV_INSN (next) = insn;
2740 }
2741 next = NEXT_INSN (BB_END (bb));
2742 if (bb->il.rtl->footer)
2743 {
2744 insn = bb->il.rtl->footer;
2745 while (insn)
2746 {
2747 if (BARRIER_P (insn))
2748 {
2749 if (PREV_INSN (insn))
2750 NEXT_INSN (PREV_INSN (insn)) = NEXT_INSN (insn);
2751 else
2752 bb->il.rtl->footer = NEXT_INSN (insn);
2753 if (NEXT_INSN (insn))
2754 PREV_INSN (NEXT_INSN (insn)) = PREV_INSN (insn);
2755 }
2756 if (LABEL_P (insn))
2757 break;
2758 insn = NEXT_INSN (insn);
2759 }
2760 if (bb->il.rtl->footer)
2761 {
2762 insn = BB_END (bb);
2763 NEXT_INSN (insn) = bb->il.rtl->footer;
2764 PREV_INSN (bb->il.rtl->footer) = insn;
2765 while (NEXT_INSN (insn))
2766 insn = NEXT_INSN (insn);
2767 NEXT_INSN (insn) = next;
2768 if (next)
2769 PREV_INSN (next) = insn;
2770 else
2771 set_last_insn (insn);
2772 }
2773 }
2774 if (bb->next_bb != EXIT_BLOCK_PTR)
2775 to = &bb->next_bb->il.rtl->header;
2776 else
2777 to = &cfg_layout_function_footer;
2778
2779 rtl_delete_block (bb);
2780
2781 if (prev)
2782 prev = NEXT_INSN (prev);
2783 else
2784 prev = get_insns ();
2785 if (next)
2786 next = PREV_INSN (next);
2787 else
2788 next = get_last_insn ();
2789
2790 if (next && NEXT_INSN (next) != prev)
2791 {
2792 remaints = unlink_insn_chain (prev, next);
2793 insn = remaints;
2794 while (NEXT_INSN (insn))
2795 insn = NEXT_INSN (insn);
2796 NEXT_INSN (insn) = *to;
2797 if (*to)
2798 PREV_INSN (*to) = insn;
2799 *to = remaints;
2800 }
2801 }
2802
2803 /* Return true when blocks A and B can be safely merged. */
2804
2805 static bool
cfg_layout_can_merge_blocks_p(basic_block a,basic_block b)2806 cfg_layout_can_merge_blocks_p (basic_block a, basic_block b)
2807 {
2808 /* If we are partitioning hot/cold basic blocks, we don't want to
2809 mess up unconditional or indirect jumps that cross between hot
2810 and cold sections.
2811
2812 Basic block partitioning may result in some jumps that appear to
2813 be optimizable (or blocks that appear to be mergeable), but which really
2814 must be left untouched (they are required to make it safely across
2815 partition boundaries). See the comments at the top of
2816 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
2817
2818 if (BB_PARTITION (a) != BB_PARTITION (b))
2819 return false;
2820
2821 /* If we would end up moving B's instructions, make sure it doesn't fall
2822 through into the exit block, since we cannot recover from a fallthrough
2823 edge into the exit block occurring in the middle of a function. */
2824 if (NEXT_INSN (BB_END (a)) != BB_HEAD (b))
2825 {
2826 edge e = find_fallthru_edge (b->succs);
2827 if (e && e->dest == EXIT_BLOCK_PTR)
2828 return false;
2829 }
2830
2831 /* There must be exactly one edge in between the blocks. */
2832 return (single_succ_p (a)
2833 && single_succ (a) == b
2834 && single_pred_p (b) == 1
2835 && a != b
2836 /* Must be simple edge. */
2837 && !(single_succ_edge (a)->flags & EDGE_COMPLEX)
2838 && a != ENTRY_BLOCK_PTR && b != EXIT_BLOCK_PTR
2839 /* If the jump insn has side effects, we can't kill the edge.
2840 When not optimizing, try_redirect_by_replacing_jump will
2841 not allow us to redirect an edge by replacing a table jump. */
2842 && (!JUMP_P (BB_END (a))
2843 || ((!optimize || reload_completed)
2844 ? simplejump_p (BB_END (a)) : onlyjump_p (BB_END (a)))));
2845 }
2846
2847 /* Merge block A and B. The blocks must be mergeable. */
2848
2849 static void
cfg_layout_merge_blocks(basic_block a,basic_block b)2850 cfg_layout_merge_blocks (basic_block a, basic_block b)
2851 {
2852 bool forwarder_p = (b->flags & BB_FORWARDER_BLOCK) != 0;
2853
2854 gcc_checking_assert (cfg_layout_can_merge_blocks_p (a, b));
2855
2856 if (dump_file)
2857 fprintf (dump_file, "Merging block %d into block %d...\n", b->index,
2858 a->index);
2859
2860 /* If there was a CODE_LABEL beginning B, delete it. */
2861 if (LABEL_P (BB_HEAD (b)))
2862 {
2863 delete_insn (BB_HEAD (b));
2864 }
2865
2866 /* We should have fallthru edge in a, or we can do dummy redirection to get
2867 it cleaned up. */
2868 if (JUMP_P (BB_END (a)))
2869 try_redirect_by_replacing_jump (EDGE_SUCC (a, 0), b, true);
2870 gcc_assert (!JUMP_P (BB_END (a)));
2871
2872 /* When not optimizing and the edge is the only place in RTL which holds
2873 some unique locus, emit a nop with that locus in between. */
2874 if (!optimize && EDGE_SUCC (a, 0)->goto_locus)
2875 {
2876 rtx insn = BB_END (a), end = PREV_INSN (BB_HEAD (a));
2877 int goto_locus = EDGE_SUCC (a, 0)->goto_locus;
2878
2879 while (insn != end && (!INSN_P (insn) || INSN_LOCATOR (insn) == 0))
2880 insn = PREV_INSN (insn);
2881 if (insn != end && locator_eq (INSN_LOCATOR (insn), goto_locus))
2882 goto_locus = 0;
2883 else
2884 {
2885 insn = BB_HEAD (b);
2886 end = NEXT_INSN (BB_END (b));
2887 while (insn != end && !INSN_P (insn))
2888 insn = NEXT_INSN (insn);
2889 if (insn != end && INSN_LOCATOR (insn) != 0
2890 && locator_eq (INSN_LOCATOR (insn), goto_locus))
2891 goto_locus = 0;
2892 }
2893 if (goto_locus)
2894 {
2895 BB_END (a) = emit_insn_after_noloc (gen_nop (), BB_END (a), a);
2896 INSN_LOCATOR (BB_END (a)) = goto_locus;
2897 }
2898 }
2899
2900 /* Possible line number notes should appear in between. */
2901 if (b->il.rtl->header)
2902 {
2903 rtx first = BB_END (a), last;
2904
2905 last = emit_insn_after_noloc (b->il.rtl->header, BB_END (a), a);
2906 /* The above might add a BARRIER as BB_END, but as barriers
2907 aren't valid parts of a bb, remove_insn doesn't update
2908 BB_END if it is a barrier. So adjust BB_END here. */
2909 while (BB_END (a) != first && BARRIER_P (BB_END (a)))
2910 BB_END (a) = PREV_INSN (BB_END (a));
2911 delete_insn_chain (NEXT_INSN (first), last, false);
2912 b->il.rtl->header = NULL;
2913 }
2914
2915 /* In the case basic blocks are not adjacent, move them around. */
2916 if (NEXT_INSN (BB_END (a)) != BB_HEAD (b))
2917 {
2918 rtx first = unlink_insn_chain (BB_HEAD (b), BB_END (b));
2919
2920 emit_insn_after_noloc (first, BB_END (a), a);
2921 /* Skip possible DELETED_LABEL insn. */
2922 if (!NOTE_INSN_BASIC_BLOCK_P (first))
2923 first = NEXT_INSN (first);
2924 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (first));
2925 BB_HEAD (b) = NULL;
2926
2927 /* emit_insn_after_noloc doesn't call df_insn_change_bb.
2928 We need to explicitly call. */
2929 update_bb_for_insn_chain (NEXT_INSN (first),
2930 BB_END (b),
2931 a);
2932
2933 delete_insn (first);
2934 }
2935 /* Otherwise just re-associate the instructions. */
2936 else
2937 {
2938 rtx insn;
2939
2940 update_bb_for_insn_chain (BB_HEAD (b), BB_END (b), a);
2941
2942 insn = BB_HEAD (b);
2943 /* Skip possible DELETED_LABEL insn. */
2944 if (!NOTE_INSN_BASIC_BLOCK_P (insn))
2945 insn = NEXT_INSN (insn);
2946 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (insn));
2947 BB_HEAD (b) = NULL;
2948 BB_END (a) = BB_END (b);
2949 delete_insn (insn);
2950 }
2951
2952 df_bb_delete (b->index);
2953
2954 /* Possible tablejumps and barriers should appear after the block. */
2955 if (b->il.rtl->footer)
2956 {
2957 if (!a->il.rtl->footer)
2958 a->il.rtl->footer = b->il.rtl->footer;
2959 else
2960 {
2961 rtx last = a->il.rtl->footer;
2962
2963 while (NEXT_INSN (last))
2964 last = NEXT_INSN (last);
2965 NEXT_INSN (last) = b->il.rtl->footer;
2966 PREV_INSN (b->il.rtl->footer) = last;
2967 }
2968 b->il.rtl->footer = NULL;
2969 }
2970
2971 /* If B was a forwarder block, propagate the locus on the edge. */
2972 if (forwarder_p && !EDGE_SUCC (b, 0)->goto_locus)
2973 EDGE_SUCC (b, 0)->goto_locus = EDGE_SUCC (a, 0)->goto_locus;
2974
2975 if (dump_file)
2976 fprintf (dump_file, "Merged blocks %d and %d.\n", a->index, b->index);
2977 }
2978
2979 /* Split edge E. */
2980
2981 static basic_block
cfg_layout_split_edge(edge e)2982 cfg_layout_split_edge (edge e)
2983 {
2984 basic_block new_bb =
2985 create_basic_block (e->src != ENTRY_BLOCK_PTR
2986 ? NEXT_INSN (BB_END (e->src)) : get_insns (),
2987 NULL_RTX, e->src);
2988
2989 if (e->dest == EXIT_BLOCK_PTR)
2990 BB_COPY_PARTITION (new_bb, e->src);
2991 else
2992 BB_COPY_PARTITION (new_bb, e->dest);
2993 make_edge (new_bb, e->dest, EDGE_FALLTHRU);
2994 redirect_edge_and_branch_force (e, new_bb);
2995
2996 return new_bb;
2997 }
2998
2999 /* Do postprocessing after making a forwarder block joined by edge FALLTHRU. */
3000
3001 static void
rtl_make_forwarder_block(edge fallthru ATTRIBUTE_UNUSED)3002 rtl_make_forwarder_block (edge fallthru ATTRIBUTE_UNUSED)
3003 {
3004 }
3005
3006 /* Return 1 if BB ends with a call, possibly followed by some
3007 instructions that must stay with the call, 0 otherwise. */
3008
3009 static bool
rtl_block_ends_with_call_p(basic_block bb)3010 rtl_block_ends_with_call_p (basic_block bb)
3011 {
3012 rtx insn = BB_END (bb);
3013
3014 while (!CALL_P (insn)
3015 && insn != BB_HEAD (bb)
3016 && (keep_with_call_p (insn)
3017 || NOTE_P (insn)
3018 || DEBUG_INSN_P (insn)))
3019 insn = PREV_INSN (insn);
3020 return (CALL_P (insn));
3021 }
3022
3023 /* Return 1 if BB ends with a conditional branch, 0 otherwise. */
3024
3025 static bool
rtl_block_ends_with_condjump_p(const_basic_block bb)3026 rtl_block_ends_with_condjump_p (const_basic_block bb)
3027 {
3028 return any_condjump_p (BB_END (bb));
3029 }
3030
3031 /* Return true if we need to add fake edge to exit.
3032 Helper function for rtl_flow_call_edges_add. */
3033
3034 static bool
need_fake_edge_p(const_rtx insn)3035 need_fake_edge_p (const_rtx insn)
3036 {
3037 if (!INSN_P (insn))
3038 return false;
3039
3040 if ((CALL_P (insn)
3041 && !SIBLING_CALL_P (insn)
3042 && !find_reg_note (insn, REG_NORETURN, NULL)
3043 && !(RTL_CONST_OR_PURE_CALL_P (insn))))
3044 return true;
3045
3046 return ((GET_CODE (PATTERN (insn)) == ASM_OPERANDS
3047 && MEM_VOLATILE_P (PATTERN (insn)))
3048 || (GET_CODE (PATTERN (insn)) == PARALLEL
3049 && asm_noperands (insn) != -1
3050 && MEM_VOLATILE_P (XVECEXP (PATTERN (insn), 0, 0)))
3051 || GET_CODE (PATTERN (insn)) == ASM_INPUT);
3052 }
3053
3054 /* Add fake edges to the function exit for any non constant and non noreturn
3055 calls, volatile inline assembly in the bitmap of blocks specified by
3056 BLOCKS or to the whole CFG if BLOCKS is zero. Return the number of blocks
3057 that were split.
3058
3059 The goal is to expose cases in which entering a basic block does not imply
3060 that all subsequent instructions must be executed. */
3061
3062 static int
rtl_flow_call_edges_add(sbitmap blocks)3063 rtl_flow_call_edges_add (sbitmap blocks)
3064 {
3065 int i;
3066 int blocks_split = 0;
3067 int last_bb = last_basic_block;
3068 bool check_last_block = false;
3069
3070 if (n_basic_blocks == NUM_FIXED_BLOCKS)
3071 return 0;
3072
3073 if (! blocks)
3074 check_last_block = true;
3075 else
3076 check_last_block = TEST_BIT (blocks, EXIT_BLOCK_PTR->prev_bb->index);
3077
3078 /* In the last basic block, before epilogue generation, there will be
3079 a fallthru edge to EXIT. Special care is required if the last insn
3080 of the last basic block is a call because make_edge folds duplicate
3081 edges, which would result in the fallthru edge also being marked
3082 fake, which would result in the fallthru edge being removed by
3083 remove_fake_edges, which would result in an invalid CFG.
3084
3085 Moreover, we can't elide the outgoing fake edge, since the block
3086 profiler needs to take this into account in order to solve the minimal
3087 spanning tree in the case that the call doesn't return.
3088
3089 Handle this by adding a dummy instruction in a new last basic block. */
3090 if (check_last_block)
3091 {
3092 basic_block bb = EXIT_BLOCK_PTR->prev_bb;
3093 rtx insn = BB_END (bb);
3094
3095 /* Back up past insns that must be kept in the same block as a call. */
3096 while (insn != BB_HEAD (bb)
3097 && keep_with_call_p (insn))
3098 insn = PREV_INSN (insn);
3099
3100 if (need_fake_edge_p (insn))
3101 {
3102 edge e;
3103
3104 e = find_edge (bb, EXIT_BLOCK_PTR);
3105 if (e)
3106 {
3107 insert_insn_on_edge (gen_use (const0_rtx), e);
3108 commit_edge_insertions ();
3109 }
3110 }
3111 }
3112
3113 /* Now add fake edges to the function exit for any non constant
3114 calls since there is no way that we can determine if they will
3115 return or not... */
3116
3117 for (i = NUM_FIXED_BLOCKS; i < last_bb; i++)
3118 {
3119 basic_block bb = BASIC_BLOCK (i);
3120 rtx insn;
3121 rtx prev_insn;
3122
3123 if (!bb)
3124 continue;
3125
3126 if (blocks && !TEST_BIT (blocks, i))
3127 continue;
3128
3129 for (insn = BB_END (bb); ; insn = prev_insn)
3130 {
3131 prev_insn = PREV_INSN (insn);
3132 if (need_fake_edge_p (insn))
3133 {
3134 edge e;
3135 rtx split_at_insn = insn;
3136
3137 /* Don't split the block between a call and an insn that should
3138 remain in the same block as the call. */
3139 if (CALL_P (insn))
3140 while (split_at_insn != BB_END (bb)
3141 && keep_with_call_p (NEXT_INSN (split_at_insn)))
3142 split_at_insn = NEXT_INSN (split_at_insn);
3143
3144 /* The handling above of the final block before the epilogue
3145 should be enough to verify that there is no edge to the exit
3146 block in CFG already. Calling make_edge in such case would
3147 cause us to mark that edge as fake and remove it later. */
3148
3149 #ifdef ENABLE_CHECKING
3150 if (split_at_insn == BB_END (bb))
3151 {
3152 e = find_edge (bb, EXIT_BLOCK_PTR);
3153 gcc_assert (e == NULL);
3154 }
3155 #endif
3156
3157 /* Note that the following may create a new basic block
3158 and renumber the existing basic blocks. */
3159 if (split_at_insn != BB_END (bb))
3160 {
3161 e = split_block (bb, split_at_insn);
3162 if (e)
3163 blocks_split++;
3164 }
3165
3166 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
3167 }
3168
3169 if (insn == BB_HEAD (bb))
3170 break;
3171 }
3172 }
3173
3174 if (blocks_split)
3175 verify_flow_info ();
3176
3177 return blocks_split;
3178 }
3179
3180 /* Add COMP_RTX as a condition at end of COND_BB. FIRST_HEAD is
3181 the conditional branch target, SECOND_HEAD should be the fall-thru
3182 there is no need to handle this here the loop versioning code handles
3183 this. the reason for SECON_HEAD is that it is needed for condition
3184 in trees, and this should be of the same type since it is a hook. */
3185 static void
rtl_lv_add_condition_to_bb(basic_block first_head,basic_block second_head ATTRIBUTE_UNUSED,basic_block cond_bb,void * comp_rtx)3186 rtl_lv_add_condition_to_bb (basic_block first_head ,
3187 basic_block second_head ATTRIBUTE_UNUSED,
3188 basic_block cond_bb, void *comp_rtx)
3189 {
3190 rtx label, seq, jump;
3191 rtx op0 = XEXP ((rtx)comp_rtx, 0);
3192 rtx op1 = XEXP ((rtx)comp_rtx, 1);
3193 enum rtx_code comp = GET_CODE ((rtx)comp_rtx);
3194 enum machine_mode mode;
3195
3196
3197 label = block_label (first_head);
3198 mode = GET_MODE (op0);
3199 if (mode == VOIDmode)
3200 mode = GET_MODE (op1);
3201
3202 start_sequence ();
3203 op0 = force_operand (op0, NULL_RTX);
3204 op1 = force_operand (op1, NULL_RTX);
3205 do_compare_rtx_and_jump (op0, op1, comp, 0,
3206 mode, NULL_RTX, NULL_RTX, label, -1);
3207 jump = get_last_insn ();
3208 JUMP_LABEL (jump) = label;
3209 LABEL_NUSES (label)++;
3210 seq = get_insns ();
3211 end_sequence ();
3212
3213 /* Add the new cond , in the new head. */
3214 emit_insn_after(seq, BB_END(cond_bb));
3215 }
3216
3217
3218 /* Given a block B with unconditional branch at its end, get the
3219 store the return the branch edge and the fall-thru edge in
3220 BRANCH_EDGE and FALLTHRU_EDGE respectively. */
3221 static void
rtl_extract_cond_bb_edges(basic_block b,edge * branch_edge,edge * fallthru_edge)3222 rtl_extract_cond_bb_edges (basic_block b, edge *branch_edge,
3223 edge *fallthru_edge)
3224 {
3225 edge e = EDGE_SUCC (b, 0);
3226
3227 if (e->flags & EDGE_FALLTHRU)
3228 {
3229 *fallthru_edge = e;
3230 *branch_edge = EDGE_SUCC (b, 1);
3231 }
3232 else
3233 {
3234 *branch_edge = e;
3235 *fallthru_edge = EDGE_SUCC (b, 1);
3236 }
3237 }
3238
3239 void
init_rtl_bb_info(basic_block bb)3240 init_rtl_bb_info (basic_block bb)
3241 {
3242 gcc_assert (!bb->il.rtl);
3243 bb->il.rtl = ggc_alloc_cleared_rtl_bb_info ();
3244 }
3245
3246 /* Returns true if it is possible to remove edge E by redirecting
3247 it to the destination of the other edge from E->src. */
3248
3249 static bool
rtl_can_remove_branch_p(const_edge e)3250 rtl_can_remove_branch_p (const_edge e)
3251 {
3252 const_basic_block src = e->src;
3253 const_basic_block target = EDGE_SUCC (src, EDGE_SUCC (src, 0) == e)->dest;
3254 const_rtx insn = BB_END (src), set;
3255
3256 /* The conditions are taken from try_redirect_by_replacing_jump. */
3257 if (target == EXIT_BLOCK_PTR)
3258 return false;
3259
3260 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
3261 return false;
3262
3263 if (find_reg_note (insn, REG_CROSSING_JUMP, NULL_RTX)
3264 || BB_PARTITION (src) != BB_PARTITION (target))
3265 return false;
3266
3267 if (!onlyjump_p (insn)
3268 || tablejump_p (insn, NULL, NULL))
3269 return false;
3270
3271 set = single_set (insn);
3272 if (!set || side_effects_p (set))
3273 return false;
3274
3275 return true;
3276 }
3277
3278 /* We do not want to declare these functions in a header file, since they
3279 should only be used through the cfghooks interface, and we do not want to
3280 move them here since it would require also moving quite a lot of related
3281 code. They are in cfglayout.c. */
3282 extern bool cfg_layout_can_duplicate_bb_p (const_basic_block);
3283 extern basic_block cfg_layout_duplicate_bb (basic_block);
3284
3285 static basic_block
rtl_duplicate_bb(basic_block bb)3286 rtl_duplicate_bb (basic_block bb)
3287 {
3288 bb = cfg_layout_duplicate_bb (bb);
3289 bb->aux = NULL;
3290 return bb;
3291 }
3292
3293 /* Implementation of CFG manipulation for linearized RTL. */
3294 struct cfg_hooks rtl_cfg_hooks = {
3295 "rtl",
3296 rtl_verify_flow_info,
3297 rtl_dump_bb,
3298 rtl_create_basic_block,
3299 rtl_redirect_edge_and_branch,
3300 rtl_redirect_edge_and_branch_force,
3301 rtl_can_remove_branch_p,
3302 rtl_delete_block,
3303 rtl_split_block,
3304 rtl_move_block_after,
3305 rtl_can_merge_blocks, /* can_merge_blocks_p */
3306 rtl_merge_blocks,
3307 rtl_predict_edge,
3308 rtl_predicted_by_p,
3309 cfg_layout_can_duplicate_bb_p,
3310 rtl_duplicate_bb,
3311 rtl_split_edge,
3312 rtl_make_forwarder_block,
3313 rtl_tidy_fallthru_edge,
3314 rtl_force_nonfallthru,
3315 rtl_block_ends_with_call_p,
3316 rtl_block_ends_with_condjump_p,
3317 rtl_flow_call_edges_add,
3318 NULL, /* execute_on_growing_pred */
3319 NULL, /* execute_on_shrinking_pred */
3320 NULL, /* duplicate loop for trees */
3321 NULL, /* lv_add_condition_to_bb */
3322 NULL, /* lv_adjust_loop_header_phi*/
3323 NULL, /* extract_cond_bb_edges */
3324 NULL /* flush_pending_stmts */
3325 };
3326
3327 /* Implementation of CFG manipulation for cfg layout RTL, where
3328 basic block connected via fallthru edges does not have to be adjacent.
3329 This representation will hopefully become the default one in future
3330 version of the compiler. */
3331
3332 struct cfg_hooks cfg_layout_rtl_cfg_hooks = {
3333 "cfglayout mode",
3334 rtl_verify_flow_info_1,
3335 rtl_dump_bb,
3336 cfg_layout_create_basic_block,
3337 cfg_layout_redirect_edge_and_branch,
3338 cfg_layout_redirect_edge_and_branch_force,
3339 rtl_can_remove_branch_p,
3340 cfg_layout_delete_block,
3341 cfg_layout_split_block,
3342 rtl_move_block_after,
3343 cfg_layout_can_merge_blocks_p,
3344 cfg_layout_merge_blocks,
3345 rtl_predict_edge,
3346 rtl_predicted_by_p,
3347 cfg_layout_can_duplicate_bb_p,
3348 cfg_layout_duplicate_bb,
3349 cfg_layout_split_edge,
3350 rtl_make_forwarder_block,
3351 NULL, /* tidy_fallthru_edge */
3352 rtl_force_nonfallthru,
3353 rtl_block_ends_with_call_p,
3354 rtl_block_ends_with_condjump_p,
3355 rtl_flow_call_edges_add,
3356 NULL, /* execute_on_growing_pred */
3357 NULL, /* execute_on_shrinking_pred */
3358 duplicate_loop_to_header_edge, /* duplicate loop for trees */
3359 rtl_lv_add_condition_to_bb, /* lv_add_condition_to_bb */
3360 NULL, /* lv_adjust_loop_header_phi*/
3361 rtl_extract_cond_bb_edges, /* extract_cond_bb_edges */
3362 NULL /* flush_pending_stmts */
3363 };
3364