This file is indexed.

/usr/include/llvm-3.9/llvm/Analysis/RegionInfoImpl.h is in llvm-3.9-dev 1:3.9.1-19ubuntu1.

This file is owned by root:root, with mode 0o644.

The actual contents of the file can be viewed below.

  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
//===- RegionInfoImpl.h - SESE region detection analysis --------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
// Detects single entry single exit regions in the control flow graph.
//===----------------------------------------------------------------------===//

#ifndef LLVM_ANALYSIS_REGIONINFOIMPL_H
#define LLVM_ANALYSIS_REGIONINFOIMPL_H

#include "llvm/ADT/PostOrderIterator.h"
#include "llvm/Analysis/DominanceFrontier.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Analysis/PostDominators.h"
#include "llvm/Analysis/RegionInfo.h"
#include "llvm/Analysis/RegionIterator.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include <algorithm>
#include <iterator>
#include <set>

namespace llvm {

#define DEBUG_TYPE "region"

//===----------------------------------------------------------------------===//
/// RegionBase Implementation
template <class Tr>
RegionBase<Tr>::RegionBase(BlockT *Entry, BlockT *Exit,
                           typename Tr::RegionInfoT *RInfo, DomTreeT *dt,
                           RegionT *Parent)
    : RegionNodeBase<Tr>(Parent, Entry, 1), RI(RInfo), DT(dt), exit(Exit) {}

template <class Tr>
RegionBase<Tr>::~RegionBase() {
  // Free the cached nodes.
  for (typename BBNodeMapT::iterator it = BBNodeMap.begin(),
                                     ie = BBNodeMap.end();
       it != ie; ++it)
    delete it->second;

  // Only clean the cache for this Region. Caches of child Regions will be
  // cleaned when the child Regions are deleted.
  BBNodeMap.clear();
}

template <class Tr>
void RegionBase<Tr>::replaceEntry(BlockT *BB) {
  this->entry.setPointer(BB);
}

template <class Tr>
void RegionBase<Tr>::replaceExit(BlockT *BB) {
  assert(exit && "No exit to replace!");
  exit = BB;
}

template <class Tr>
void RegionBase<Tr>::replaceEntryRecursive(BlockT *NewEntry) {
  std::vector<RegionT *> RegionQueue;
  BlockT *OldEntry = getEntry();

  RegionQueue.push_back(static_cast<RegionT *>(this));
  while (!RegionQueue.empty()) {
    RegionT *R = RegionQueue.back();
    RegionQueue.pop_back();

    R->replaceEntry(NewEntry);
    for (typename RegionT::const_iterator RI = R->begin(), RE = R->end();
         RI != RE; ++RI) {
      if ((*RI)->getEntry() == OldEntry)
        RegionQueue.push_back(RI->get());
    }
  }
}

template <class Tr>
void RegionBase<Tr>::replaceExitRecursive(BlockT *NewExit) {
  std::vector<RegionT *> RegionQueue;
  BlockT *OldExit = getExit();

  RegionQueue.push_back(static_cast<RegionT *>(this));
  while (!RegionQueue.empty()) {
    RegionT *R = RegionQueue.back();
    RegionQueue.pop_back();

    R->replaceExit(NewExit);
    for (typename RegionT::const_iterator RI = R->begin(), RE = R->end();
         RI != RE; ++RI) {
      if ((*RI)->getExit() == OldExit)
        RegionQueue.push_back(RI->get());
    }
  }
}

template <class Tr>
bool RegionBase<Tr>::contains(const BlockT *B) const {
  BlockT *BB = const_cast<BlockT *>(B);

  if (!DT->getNode(BB))
    return false;

  BlockT *entry = getEntry(), *exit = getExit();

  // Toplevel region.
  if (!exit)
    return true;

  return (DT->dominates(entry, BB) &&
          !(DT->dominates(exit, BB) && DT->dominates(entry, exit)));
}

template <class Tr>
bool RegionBase<Tr>::contains(const LoopT *L) const {
  // BBs that are not part of any loop are element of the Loop
  // described by the NULL pointer. This loop is not part of any region,
  // except if the region describes the whole function.
  if (!L)
    return getExit() == nullptr;

  if (!contains(L->getHeader()))
    return false;

  SmallVector<BlockT *, 8> ExitingBlocks;
  L->getExitingBlocks(ExitingBlocks);

  for (BlockT *BB : ExitingBlocks) {
    if (!contains(BB))
      return false;
  }

  return true;
}

template <class Tr>
typename Tr::LoopT *RegionBase<Tr>::outermostLoopInRegion(LoopT *L) const {
  if (!contains(L))
    return nullptr;

  while (L && contains(L->getParentLoop())) {
    L = L->getParentLoop();
  }

  return L;
}

template <class Tr>
typename Tr::LoopT *RegionBase<Tr>::outermostLoopInRegion(LoopInfoT *LI,
                                                          BlockT *BB) const {
  assert(LI && BB && "LI and BB cannot be null!");
  LoopT *L = LI->getLoopFor(BB);
  return outermostLoopInRegion(L);
}

template <class Tr>
typename RegionBase<Tr>::BlockT *RegionBase<Tr>::getEnteringBlock() const {
  BlockT *entry = getEntry();
  BlockT *Pred;
  BlockT *enteringBlock = nullptr;

  for (PredIterTy PI = InvBlockTraits::child_begin(entry),
                  PE = InvBlockTraits::child_end(entry);
       PI != PE; ++PI) {
    Pred = *PI;
    if (DT->getNode(Pred) && !contains(Pred)) {
      if (enteringBlock)
        return nullptr;

      enteringBlock = Pred;
    }
  }

  return enteringBlock;
}

template <class Tr>
typename RegionBase<Tr>::BlockT *RegionBase<Tr>::getExitingBlock() const {
  BlockT *exit = getExit();
  BlockT *Pred;
  BlockT *exitingBlock = nullptr;

  if (!exit)
    return nullptr;

  for (PredIterTy PI = InvBlockTraits::child_begin(exit),
                  PE = InvBlockTraits::child_end(exit);
       PI != PE; ++PI) {
    Pred = *PI;
    if (contains(Pred)) {
      if (exitingBlock)
        return nullptr;

      exitingBlock = Pred;
    }
  }

  return exitingBlock;
}

template <class Tr>
bool RegionBase<Tr>::isSimple() const {
  return !isTopLevelRegion() && getEnteringBlock() && getExitingBlock();
}

template <class Tr>
std::string RegionBase<Tr>::getNameStr() const {
  std::string exitName;
  std::string entryName;

  if (getEntry()->getName().empty()) {
    raw_string_ostream OS(entryName);

    getEntry()->printAsOperand(OS, false);
  } else
    entryName = getEntry()->getName();

  if (getExit()) {
    if (getExit()->getName().empty()) {
      raw_string_ostream OS(exitName);

      getExit()->printAsOperand(OS, false);
    } else
      exitName = getExit()->getName();
  } else
    exitName = "<Function Return>";

  return entryName + " => " + exitName;
}

template <class Tr>
void RegionBase<Tr>::verifyBBInRegion(BlockT *BB) const {
  if (!contains(BB))
    llvm_unreachable("Broken region found: enumerated BB not in region!");

  BlockT *entry = getEntry(), *exit = getExit();

  for (SuccIterTy SI = BlockTraits::child_begin(BB),
                  SE = BlockTraits::child_end(BB);
       SI != SE; ++SI) {
    if (!contains(*SI) && exit != *SI)
      llvm_unreachable("Broken region found: edges leaving the region must go "
                       "to the exit node!");
  }

  if (entry != BB) {
    for (PredIterTy SI = InvBlockTraits::child_begin(BB),
                    SE = InvBlockTraits::child_end(BB);
         SI != SE; ++SI) {
      if (!contains(*SI))
        llvm_unreachable("Broken region found: edges entering the region must "
                         "go to the entry node!");
    }
  }
}

template <class Tr>
void RegionBase<Tr>::verifyWalk(BlockT *BB, std::set<BlockT *> *visited) const {
  BlockT *exit = getExit();

  visited->insert(BB);

  verifyBBInRegion(BB);

  for (SuccIterTy SI = BlockTraits::child_begin(BB),
                  SE = BlockTraits::child_end(BB);
       SI != SE; ++SI) {
    if (*SI != exit && visited->find(*SI) == visited->end())
      verifyWalk(*SI, visited);
  }
}

template <class Tr>
void RegionBase<Tr>::verifyRegion() const {
  // Only do verification when user wants to, otherwise this expensive check
  // will be invoked by PMDataManager::verifyPreservedAnalysis when
  // a regionpass (marked PreservedAll) finish.
  if (!RegionInfoBase<Tr>::VerifyRegionInfo)
    return;

  std::set<BlockT *> visited;
  verifyWalk(getEntry(), &visited);
}

template <class Tr>
void RegionBase<Tr>::verifyRegionNest() const {
  for (typename RegionT::const_iterator RI = begin(), RE = end(); RI != RE;
       ++RI)
    (*RI)->verifyRegionNest();

  verifyRegion();
}

template <class Tr>
typename RegionBase<Tr>::element_iterator RegionBase<Tr>::element_begin() {
  return GraphTraits<RegionT *>::nodes_begin(static_cast<RegionT *>(this));
}

template <class Tr>
typename RegionBase<Tr>::element_iterator RegionBase<Tr>::element_end() {
  return GraphTraits<RegionT *>::nodes_end(static_cast<RegionT *>(this));
}

template <class Tr>
typename RegionBase<Tr>::const_element_iterator
RegionBase<Tr>::element_begin() const {
  return GraphTraits<const RegionT *>::nodes_begin(
      static_cast<const RegionT *>(this));
}

template <class Tr>
typename RegionBase<Tr>::const_element_iterator
RegionBase<Tr>::element_end() const {
  return GraphTraits<const RegionT *>::nodes_end(
      static_cast<const RegionT *>(this));
}

template <class Tr>
typename Tr::RegionT *RegionBase<Tr>::getSubRegionNode(BlockT *BB) const {
  typedef typename Tr::RegionT RegionT;
  RegionT *R = RI->getRegionFor(BB);

  if (!R || R == this)
    return nullptr;

  // If we pass the BB out of this region, that means our code is broken.
  assert(contains(R) && "BB not in current region!");

  while (contains(R->getParent()) && R->getParent() != this)
    R = R->getParent();

  if (R->getEntry() != BB)
    return nullptr;

  return R;
}

template <class Tr>
typename Tr::RegionNodeT *RegionBase<Tr>::getBBNode(BlockT *BB) const {
  assert(contains(BB) && "Can get BB node out of this region!");

  typename BBNodeMapT::const_iterator at = BBNodeMap.find(BB);

  if (at != BBNodeMap.end())
    return at->second;

  auto Deconst = const_cast<RegionBase<Tr> *>(this);
  RegionNodeT *NewNode = new RegionNodeT(static_cast<RegionT *>(Deconst), BB);
  BBNodeMap.insert(std::make_pair(BB, NewNode));
  return NewNode;
}

template <class Tr>
typename Tr::RegionNodeT *RegionBase<Tr>::getNode(BlockT *BB) const {
  assert(contains(BB) && "Can get BB node out of this region!");
  if (RegionT *Child = getSubRegionNode(BB))
    return Child->getNode();

  return getBBNode(BB);
}

template <class Tr>
void RegionBase<Tr>::transferChildrenTo(RegionT *To) {
  for (iterator I = begin(), E = end(); I != E; ++I) {
    (*I)->parent = To;
    To->children.push_back(std::move(*I));
  }
  children.clear();
}

template <class Tr>
void RegionBase<Tr>::addSubRegion(RegionT *SubRegion, bool moveChildren) {
  assert(!SubRegion->parent && "SubRegion already has a parent!");
  assert(std::find_if(begin(), end(), [&](const std::unique_ptr<RegionT> &R) {
           return R.get() == SubRegion;
         }) == children.end() &&
         "Subregion already exists!");

  SubRegion->parent = static_cast<RegionT *>(this);
  children.push_back(std::unique_ptr<RegionT>(SubRegion));

  if (!moveChildren)
    return;

  assert(SubRegion->children.empty() &&
         "SubRegions that contain children are not supported");

  for (element_iterator I = element_begin(), E = element_end(); I != E; ++I) {
    if (!(*I)->isSubRegion()) {
      BlockT *BB = (*I)->template getNodeAs<BlockT>();

      if (SubRegion->contains(BB))
        RI->setRegionFor(BB, SubRegion);
    }
  }

  std::vector<std::unique_ptr<RegionT>> Keep;
  for (iterator I = begin(), E = end(); I != E; ++I) {
    if (SubRegion->contains(I->get()) && I->get() != SubRegion) {
      (*I)->parent = SubRegion;
      SubRegion->children.push_back(std::move(*I));
    } else
      Keep.push_back(std::move(*I));
  }

  children.clear();
  children.insert(
      children.begin(),
      std::move_iterator<typename RegionSet::iterator>(Keep.begin()),
      std::move_iterator<typename RegionSet::iterator>(Keep.end()));
}

template <class Tr>
typename Tr::RegionT *RegionBase<Tr>::removeSubRegion(RegionT *Child) {
  assert(Child->parent == this && "Child is not a child of this region!");
  Child->parent = nullptr;
  typename RegionSet::iterator I = std::find_if(
      children.begin(), children.end(),
      [&](const std::unique_ptr<RegionT> &R) { return R.get() == Child; });
  assert(I != children.end() && "Region does not exit. Unable to remove.");
  children.erase(children.begin() + (I - begin()));
  return Child;
}

template <class Tr>
unsigned RegionBase<Tr>::getDepth() const {
  unsigned Depth = 0;

  for (RegionT *R = getParent(); R != nullptr; R = R->getParent())
    ++Depth;

  return Depth;
}

template <class Tr>
typename Tr::RegionT *RegionBase<Tr>::getExpandedRegion() const {
  unsigned NumSuccessors = Tr::getNumSuccessors(exit);

  if (NumSuccessors == 0)
    return nullptr;

  RegionT *R = RI->getRegionFor(exit);

  if (R->getEntry() != exit) {
    for (PredIterTy PI = InvBlockTraits::child_begin(getExit()),
                    PE = InvBlockTraits::child_end(getExit());
         PI != PE; ++PI)
      if (!contains(*PI))
        return nullptr;
    if (Tr::getNumSuccessors(exit) == 1)
      return new RegionT(getEntry(), *BlockTraits::child_begin(exit), RI, DT);
    return nullptr;
  }

  while (R->getParent() && R->getParent()->getEntry() == exit)
    R = R->getParent();

  for (PredIterTy PI = InvBlockTraits::child_begin(getExit()),
                  PE = InvBlockTraits::child_end(getExit());
       PI != PE; ++PI) {
    if (!(contains(*PI) || R->contains(*PI)))
      return nullptr;
  }

  return new RegionT(getEntry(), R->getExit(), RI, DT);
}

template <class Tr>
void RegionBase<Tr>::print(raw_ostream &OS, bool print_tree, unsigned level,
                           PrintStyle Style) const {
  if (print_tree)
    OS.indent(level * 2) << '[' << level << "] " << getNameStr();
  else
    OS.indent(level * 2) << getNameStr();

  OS << '\n';

  if (Style != PrintNone) {
    OS.indent(level * 2) << "{\n";
    OS.indent(level * 2 + 2);

    if (Style == PrintBB) {
      for (const auto *BB : blocks())
        OS << BB->getName() << ", "; // TODO: remove the last ","
    } else if (Style == PrintRN) {
      for (const_element_iterator I = element_begin(), E = element_end();
           I != E; ++I) {
        OS << **I << ", "; // TODO: remove the last ",
      }
    }

    OS << '\n';
  }

  if (print_tree) {
    for (const_iterator RI = begin(), RE = end(); RI != RE; ++RI)
      (*RI)->print(OS, print_tree, level + 1, Style);
  }

  if (Style != PrintNone)
    OS.indent(level * 2) << "} \n";
}

#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
template <class Tr>
void RegionBase<Tr>::dump() const {
  print(dbgs(), true, getDepth(), RegionInfoBase<Tr>::printStyle);
}
#endif

template <class Tr>
void RegionBase<Tr>::clearNodeCache() {
  // Free the cached nodes.
  for (typename BBNodeMapT::iterator I = BBNodeMap.begin(),
                                     IE = BBNodeMap.end();
       I != IE; ++I)
    delete I->second;

  BBNodeMap.clear();
  for (typename RegionT::iterator RI = begin(), RE = end(); RI != RE; ++RI)
    (*RI)->clearNodeCache();
}

//===----------------------------------------------------------------------===//
// RegionInfoBase implementation
//

template <class Tr>
RegionInfoBase<Tr>::RegionInfoBase()
    : TopLevelRegion(nullptr) {}

template <class Tr>
RegionInfoBase<Tr>::~RegionInfoBase() {
  releaseMemory();
}

template <class Tr>
void RegionInfoBase<Tr>::verifyBBMap(const RegionT *R) const {
  assert(R && "Re must be non-null");
  for (auto I = R->element_begin(), E = R->element_end(); I != E; ++I) {
    if (I->isSubRegion()) {
      const RegionT *SR = I->template getNodeAs<RegionT>();
      verifyBBMap(SR);
    } else {
      BlockT *BB = I->template getNodeAs<BlockT>();
      if (getRegionFor(BB) != R)
        llvm_unreachable("BB map does not match region nesting");
    }
  }
}

template <class Tr>
bool RegionInfoBase<Tr>::isCommonDomFrontier(BlockT *BB, BlockT *entry,
                                             BlockT *exit) const {
  for (PredIterTy PI = InvBlockTraits::child_begin(BB),
                  PE = InvBlockTraits::child_end(BB);
       PI != PE; ++PI) {
    BlockT *P = *PI;
    if (DT->dominates(entry, P) && !DT->dominates(exit, P))
      return false;
  }

  return true;
}

template <class Tr>
bool RegionInfoBase<Tr>::isRegion(BlockT *entry, BlockT *exit) const {
  assert(entry && exit && "entry and exit must not be null!");
  typedef typename DomFrontierT::DomSetType DST;

  DST *entrySuccs = &DF->find(entry)->second;

  // Exit is the header of a loop that contains the entry. In this case,
  // the dominance frontier must only contain the exit.
  if (!DT->dominates(entry, exit)) {
    for (typename DST::iterator SI = entrySuccs->begin(),
                                SE = entrySuccs->end();
         SI != SE; ++SI) {
      if (*SI != exit && *SI != entry)
        return false;
    }

    return true;
  }

  DST *exitSuccs = &DF->find(exit)->second;

  // Do not allow edges leaving the region.
  for (typename DST::iterator SI = entrySuccs->begin(), SE = entrySuccs->end();
       SI != SE; ++SI) {
    if (*SI == exit || *SI == entry)
      continue;
    if (exitSuccs->find(*SI) == exitSuccs->end())
      return false;
    if (!isCommonDomFrontier(*SI, entry, exit))
      return false;
  }

  // Do not allow edges pointing into the region.
  for (typename DST::iterator SI = exitSuccs->begin(), SE = exitSuccs->end();
       SI != SE; ++SI) {
    if (DT->properlyDominates(entry, *SI) && *SI != exit)
      return false;
  }

  return true;
}

template <class Tr>
void RegionInfoBase<Tr>::insertShortCut(BlockT *entry, BlockT *exit,
                                        BBtoBBMap *ShortCut) const {
  assert(entry && exit && "entry and exit must not be null!");

  typename BBtoBBMap::iterator e = ShortCut->find(exit);

  if (e == ShortCut->end())
    // No further region at exit available.
    (*ShortCut)[entry] = exit;
  else {
    // We found a region e that starts at exit. Therefore (entry, e->second)
    // is also a region, that is larger than (entry, exit). Insert the
    // larger one.
    BlockT *BB = e->second;
    (*ShortCut)[entry] = BB;
  }
}

template <class Tr>
typename Tr::DomTreeNodeT *
RegionInfoBase<Tr>::getNextPostDom(DomTreeNodeT *N, BBtoBBMap *ShortCut) const {
  typename BBtoBBMap::iterator e = ShortCut->find(N->getBlock());

  if (e == ShortCut->end())
    return N->getIDom();

  return PDT->getNode(e->second)->getIDom();
}

template <class Tr>
bool RegionInfoBase<Tr>::isTrivialRegion(BlockT *entry, BlockT *exit) const {
  assert(entry && exit && "entry and exit must not be null!");

  unsigned num_successors =
      BlockTraits::child_end(entry) - BlockTraits::child_begin(entry);

  if (num_successors <= 1 && exit == *(BlockTraits::child_begin(entry)))
    return true;

  return false;
}

template <class Tr>
typename Tr::RegionT *RegionInfoBase<Tr>::createRegion(BlockT *entry,
                                                       BlockT *exit) {
  assert(entry && exit && "entry and exit must not be null!");

  if (isTrivialRegion(entry, exit))
    return nullptr;

  RegionT *region =
      new RegionT(entry, exit, static_cast<RegionInfoT *>(this), DT);
  BBtoRegion.insert(std::make_pair(entry, region));

#ifdef EXPENSIVE_CHECKS
  region->verifyRegion();
#else
  DEBUG(region->verifyRegion());
#endif

  updateStatistics(region);
  return region;
}

template <class Tr>
void RegionInfoBase<Tr>::findRegionsWithEntry(BlockT *entry,
                                              BBtoBBMap *ShortCut) {
  assert(entry);

  DomTreeNodeT *N = PDT->getNode(entry);
  if (!N)
    return;

  RegionT *lastRegion = nullptr;
  BlockT *lastExit = entry;

  // As only a BasicBlock that postdominates entry can finish a region, walk the
  // post dominance tree upwards.
  while ((N = getNextPostDom(N, ShortCut))) {
    BlockT *exit = N->getBlock();

    if (!exit)
      break;

    if (isRegion(entry, exit)) {
      RegionT *newRegion = createRegion(entry, exit);

      if (lastRegion)
        newRegion->addSubRegion(lastRegion);

      lastRegion = newRegion;
      lastExit = exit;
    }

    // This can never be a region, so stop the search.
    if (!DT->dominates(entry, exit))
      break;
  }

  // Tried to create regions from entry to lastExit.  Next time take a
  // shortcut from entry to lastExit.
  if (lastExit != entry)
    insertShortCut(entry, lastExit, ShortCut);
}

template <class Tr>
void RegionInfoBase<Tr>::scanForRegions(FuncT &F, BBtoBBMap *ShortCut) {
  typedef typename std::add_pointer<FuncT>::type FuncPtrT;
  BlockT *entry = GraphTraits<FuncPtrT>::getEntryNode(&F);
  DomTreeNodeT *N = DT->getNode(entry);

  // Iterate over the dominance tree in post order to start with the small
  // regions from the bottom of the dominance tree.  If the small regions are
  // detected first, detection of bigger regions is faster, as we can jump
  // over the small regions.
  for (auto DomNode : post_order(N))
    findRegionsWithEntry(DomNode->getBlock(), ShortCut);
}

template <class Tr>
typename Tr::RegionT *RegionInfoBase<Tr>::getTopMostParent(RegionT *region) {
  while (region->getParent())
    region = region->getParent();

  return region;
}

template <class Tr>
void RegionInfoBase<Tr>::buildRegionsTree(DomTreeNodeT *N, RegionT *region) {
  BlockT *BB = N->getBlock();

  // Passed region exit
  while (BB == region->getExit())
    region = region->getParent();

  typename BBtoRegionMap::iterator it = BBtoRegion.find(BB);

  // This basic block is a start block of a region. It is already in the
  // BBtoRegion relation. Only the child basic blocks have to be updated.
  if (it != BBtoRegion.end()) {
    RegionT *newRegion = it->second;
    region->addSubRegion(getTopMostParent(newRegion));
    region = newRegion;
  } else {
    BBtoRegion[BB] = region;
  }

  for (typename DomTreeNodeT::iterator CI = N->begin(), CE = N->end(); CI != CE;
       ++CI) {
    buildRegionsTree(*CI, region);
  }
}

#ifdef EXPENSIVE_CHECKS
template <class Tr>
bool RegionInfoBase<Tr>::VerifyRegionInfo = true;
#else
template <class Tr>
bool RegionInfoBase<Tr>::VerifyRegionInfo = false;
#endif

template <class Tr>
typename Tr::RegionT::PrintStyle RegionInfoBase<Tr>::printStyle =
    RegionBase<Tr>::PrintNone;

template <class Tr>
void RegionInfoBase<Tr>::print(raw_ostream &OS) const {
  OS << "Region tree:\n";
  TopLevelRegion->print(OS, true, 0, printStyle);
  OS << "End region tree\n";
}

#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
template <class Tr>
void RegionInfoBase<Tr>::dump() const { print(dbgs()); }
#endif

template <class Tr>
void RegionInfoBase<Tr>::releaseMemory() {
  BBtoRegion.clear();
  if (TopLevelRegion)
    delete TopLevelRegion;
  TopLevelRegion = nullptr;
}

template <class Tr>
void RegionInfoBase<Tr>::verifyAnalysis() const {
  // Do only verify regions if explicitely activated using EXPENSIVE_CHECKS or
  // -verify-region-info
  if (!RegionInfoBase<Tr>::VerifyRegionInfo)
    return;

  TopLevelRegion->verifyRegionNest();

  verifyBBMap(TopLevelRegion);
}

// Region pass manager support.
template <class Tr>
typename Tr::RegionT *RegionInfoBase<Tr>::getRegionFor(BlockT *BB) const {
  typename BBtoRegionMap::const_iterator I = BBtoRegion.find(BB);
  return I != BBtoRegion.end() ? I->second : nullptr;
}

template <class Tr>
void RegionInfoBase<Tr>::setRegionFor(BlockT *BB, RegionT *R) {
  BBtoRegion[BB] = R;
}

template <class Tr>
typename Tr::RegionT *RegionInfoBase<Tr>::operator[](BlockT *BB) const {
  return getRegionFor(BB);
}

template <class Tr>
typename RegionInfoBase<Tr>::BlockT *
RegionInfoBase<Tr>::getMaxRegionExit(BlockT *BB) const {
  BlockT *Exit = nullptr;

  while (true) {
    // Get largest region that starts at BB.
    RegionT *R = getRegionFor(BB);
    while (R && R->getParent() && R->getParent()->getEntry() == BB)
      R = R->getParent();

    // Get the single exit of BB.
    if (R && R->getEntry() == BB)
      Exit = R->getExit();
    else if (++BlockTraits::child_begin(BB) == BlockTraits::child_end(BB))
      Exit = *BlockTraits::child_begin(BB);
    else // No single exit exists.
      return Exit;

    // Get largest region that starts at Exit.
    RegionT *ExitR = getRegionFor(Exit);
    while (ExitR && ExitR->getParent() &&
           ExitR->getParent()->getEntry() == Exit)
      ExitR = ExitR->getParent();

    for (PredIterTy PI = InvBlockTraits::child_begin(Exit),
                    PE = InvBlockTraits::child_end(Exit);
         PI != PE; ++PI) {
      if (!R->contains(*PI) && !ExitR->contains(*PI))
        break;
    }

    // This stops infinite cycles.
    if (DT->dominates(Exit, BB))
      break;

    BB = Exit;
  }

  return Exit;
}

template <class Tr>
typename Tr::RegionT *RegionInfoBase<Tr>::getCommonRegion(RegionT *A,
                                                          RegionT *B) const {
  assert(A && B && "One of the Regions is NULL");

  if (A->contains(B))
    return A;

  while (!B->contains(A))
    B = B->getParent();

  return B;
}

template <class Tr>
typename Tr::RegionT *
RegionInfoBase<Tr>::getCommonRegion(SmallVectorImpl<RegionT *> &Regions) const {
  RegionT *ret = Regions.back();
  Regions.pop_back();

  for (RegionT *R : Regions)
    ret = getCommonRegion(ret, R);

  return ret;
}

template <class Tr>
typename Tr::RegionT *
RegionInfoBase<Tr>::getCommonRegion(SmallVectorImpl<BlockT *> &BBs) const {
  RegionT *ret = getRegionFor(BBs.back());
  BBs.pop_back();

  for (BlockT *BB : BBs)
    ret = getCommonRegion(ret, getRegionFor(BB));

  return ret;
}

template <class Tr>
void RegionInfoBase<Tr>::calculate(FuncT &F) {
  typedef typename std::add_pointer<FuncT>::type FuncPtrT;

  // ShortCut a function where for every BB the exit of the largest region
  // starting with BB is stored. These regions can be threated as single BBS.
  // This improves performance on linear CFGs.
  BBtoBBMap ShortCut;

  scanForRegions(F, &ShortCut);
  BlockT *BB = GraphTraits<FuncPtrT>::getEntryNode(&F);
  buildRegionsTree(DT->getNode(BB), TopLevelRegion);
}

#undef DEBUG_TYPE

} // end namespace llvm

#endif