1//===- RegionInfoImpl.h - SESE region detection analysis --------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8// Detects single entry single exit regions in the control flow graph.
9//===----------------------------------------------------------------------===//
10
11#ifndef LLVM_ANALYSIS_REGIONINFOIMPL_H
12#define LLVM_ANALYSIS_REGIONINFOIMPL_H
13
14#include "llvm/ADT/GraphTraits.h"
15#include "llvm/ADT/PostOrderIterator.h"
16#include "llvm/ADT/STLExtras.h"
17#include "llvm/ADT/SmallVector.h"
18#include "llvm/Analysis/LoopInfo.h"
19#include "llvm/Analysis/PostDominators.h"
20#include "llvm/Analysis/RegionInfo.h"
21#include "llvm/Analysis/RegionIterator.h"
22#include "llvm/Config/llvm-config.h"
23#include "llvm/Support/Debug.h"
24#include "llvm/Support/ErrorHandling.h"
25#include <algorithm>
26#include <cassert>
27#include <iterator>
28#include <memory>
29#include <set>
30#include <string>
31#include <type_traits>
32#include <vector>
33
34#define DEBUG_TYPE "region"
35
36namespace llvm {
37class raw_ostream;
38
39//===----------------------------------------------------------------------===//
40/// RegionBase Implementation
41template <class Tr>
42RegionBase<Tr>::RegionBase(BlockT *Entry, BlockT *Exit,
43                           typename Tr::RegionInfoT *RInfo, DomTreeT *dt,
44                           RegionT *Parent)
45    : RegionNodeBase<Tr>(Parent, Entry, 1), RI(RInfo), DT(dt), exit(Exit) {}
46
47template <class Tr>
48RegionBase<Tr>::~RegionBase() {
49  // Only clean the cache for this Region. Caches of child Regions will be
50  // cleaned when the child Regions are deleted.
51  BBNodeMap.clear();
52}
53
54template <class Tr>
55void RegionBase<Tr>::replaceEntry(BlockT *BB) {
56  this->entry.setPointer(BB);
57}
58
59template <class Tr>
60void RegionBase<Tr>::replaceExit(BlockT *BB) {
61  assert(exit && "No exit to replace!");
62  exit = BB;
63}
64
65template <class Tr>
66void RegionBase<Tr>::replaceEntryRecursive(BlockT *NewEntry) {
67  std::vector<RegionT *> RegionQueue;
68  BlockT *OldEntry = getEntry();
69
70  RegionQueue.push_back(static_cast<RegionT *>(this));
71  while (!RegionQueue.empty()) {
72    RegionT *R = RegionQueue.back();
73    RegionQueue.pop_back();
74
75    R->replaceEntry(NewEntry);
76    for (std::unique_ptr<RegionT> &Child : *R) {
77      if (Child->getEntry() == OldEntry)
78        RegionQueue.push_back(Child.get());
79    }
80  }
81}
82
83template <class Tr>
84void RegionBase<Tr>::replaceExitRecursive(BlockT *NewExit) {
85  std::vector<RegionT *> RegionQueue;
86  BlockT *OldExit = getExit();
87
88  RegionQueue.push_back(static_cast<RegionT *>(this));
89  while (!RegionQueue.empty()) {
90    RegionT *R = RegionQueue.back();
91    RegionQueue.pop_back();
92
93    R->replaceExit(NewExit);
94    for (std::unique_ptr<RegionT> &Child : *R) {
95      if (Child->getExit() == OldExit)
96        RegionQueue.push_back(Child.get());
97    }
98  }
99}
100
101template <class Tr>
102bool RegionBase<Tr>::contains(const BlockT *B) const {
103  BlockT *BB = const_cast<BlockT *>(B);
104
105  if (!DT->getNode(BB))
106    return false;
107
108  BlockT *entry = getEntry(), *exit = getExit();
109
110  // Toplevel region.
111  if (!exit)
112    return true;
113
114  return (DT->dominates(entry, BB) &&
115          !(DT->dominates(exit, BB) && DT->dominates(entry, exit)));
116}
117
118template <class Tr>
119bool RegionBase<Tr>::contains(const LoopT *L) const {
120  // BBs that are not part of any loop are element of the Loop
121  // described by the NULL pointer. This loop is not part of any region,
122  // except if the region describes the whole function.
123  if (!L)
124    return getExit() == nullptr;
125
126  if (!contains(L->getHeader()))
127    return false;
128
129  SmallVector<BlockT *, 8> ExitingBlocks;
130  L->getExitingBlocks(ExitingBlocks);
131
132  for (BlockT *BB : ExitingBlocks) {
133    if (!contains(BB))
134      return false;
135  }
136
137  return true;
138}
139
140template <class Tr>
141typename Tr::LoopT *RegionBase<Tr>::outermostLoopInRegion(LoopT *L) const {
142  if (!contains(L))
143    return nullptr;
144
145  while (L && contains(L->getParentLoop())) {
146    L = L->getParentLoop();
147  }
148
149  return L;
150}
151
152template <class Tr>
153typename Tr::LoopT *RegionBase<Tr>::outermostLoopInRegion(LoopInfoT *LI,
154                                                          BlockT *BB) const {
155  assert(LI && BB && "LI and BB cannot be null!");
156  LoopT *L = LI->getLoopFor(BB);
157  return outermostLoopInRegion(L);
158}
159
160template <class Tr>
161typename RegionBase<Tr>::BlockT *RegionBase<Tr>::getEnteringBlock() const {
162  auto isEnteringBlock = [&](BlockT *Pred, bool AllowRepeats) -> BlockT * {
163    assert(!AllowRepeats && "Unexpected parameter value.");
164    return DT->getNode(Pred) && !contains(Pred) ? Pred : nullptr;
165  };
166  return find_singleton<BlockT>(llvm::inverse_children<BlockT *>(getEntry()),
167                                isEnteringBlock);
168}
169
170template <class Tr>
171bool RegionBase<Tr>::getExitingBlocks(
172    SmallVectorImpl<BlockT *> &Exitings) const {
173  bool CoverAll = true;
174
175  if (!exit)
176    return CoverAll;
177
178  for (BlockT *Pred : llvm::inverse_children<BlockT *>(exit)) {
179    if (contains(Pred)) {
180      Exitings.push_back(Pred);
181      continue;
182    }
183
184    CoverAll = false;
185  }
186
187  return CoverAll;
188}
189
190template <class Tr>
191typename RegionBase<Tr>::BlockT *RegionBase<Tr>::getExitingBlock() const {
192  BlockT *exit = getExit();
193  if (!exit)
194    return nullptr;
195
196  auto isContained = [&](BlockT *Pred, bool AllowRepeats) -> BlockT * {
197    assert(!AllowRepeats && "Unexpected parameter value.");
198    return contains(Pred) ? Pred : nullptr;
199  };
200  return find_singleton<BlockT>(llvm::inverse_children<BlockT *>(exit),
201                                isContained);
202}
203
204template <class Tr>
205bool RegionBase<Tr>::isSimple() const {
206  return !isTopLevelRegion() && getEnteringBlock() && getExitingBlock();
207}
208
209template <class Tr>
210std::string RegionBase<Tr>::getNameStr() const {
211  std::string exitName;
212  std::string entryName;
213
214  if (getEntry()->getName().empty()) {
215    raw_string_ostream OS(entryName);
216
217    getEntry()->printAsOperand(OS, false);
218  } else
219    entryName = std::string(getEntry()->getName());
220
221  if (getExit()) {
222    if (getExit()->getName().empty()) {
223      raw_string_ostream OS(exitName);
224
225      getExit()->printAsOperand(OS, false);
226    } else
227      exitName = std::string(getExit()->getName());
228  } else
229    exitName = "<Function Return>";
230
231  return entryName + " => " + exitName;
232}
233
234template <class Tr>
235void RegionBase<Tr>::verifyBBInRegion(BlockT *BB) const {
236  if (!contains(BB))
237    report_fatal_error("Broken region found: enumerated BB not in region!");
238
239  BlockT *entry = getEntry(), *exit = getExit();
240
241  for (BlockT *Succ : llvm::children<BlockT *>(BB)) {
242    if (!contains(Succ) && exit != Succ)
243      report_fatal_error("Broken region found: edges leaving the region must go "
244                         "to the exit node!");
245  }
246
247  if (entry != BB) {
248    for (BlockT *Pred : llvm::inverse_children<BlockT *>(BB)) {
249      // Allow predecessors that are unreachable, as these are ignored during
250      // region analysis.
251      if (!contains(Pred) && DT->isReachableFromEntry(Pred))
252        report_fatal_error("Broken region found: edges entering the region must "
253                           "go to the entry node!");
254    }
255  }
256}
257
258template <class Tr>
259void RegionBase<Tr>::verifyWalk(BlockT *BB, std::set<BlockT *> *visited) const {
260  BlockT *exit = getExit();
261
262  visited->insert(BB);
263
264  verifyBBInRegion(BB);
265
266  for (BlockT *Succ : llvm::children<BlockT *>(BB)) {
267    if (Succ != exit && visited->find(Succ) == visited->end())
268      verifyWalk(Succ, visited);
269  }
270}
271
272template <class Tr>
273void RegionBase<Tr>::verifyRegion() const {
274  // Only do verification when user wants to, otherwise this expensive check
275  // will be invoked by PMDataManager::verifyPreservedAnalysis when
276  // a regionpass (marked PreservedAll) finish.
277  if (!RegionInfoBase<Tr>::VerifyRegionInfo)
278    return;
279
280  std::set<BlockT *> visited;
281  verifyWalk(getEntry(), &visited);
282}
283
284template <class Tr>
285void RegionBase<Tr>::verifyRegionNest() const {
286  for (const std::unique_ptr<RegionT> &R : *this)
287    R->verifyRegionNest();
288
289  verifyRegion();
290}
291
292template <class Tr>
293typename RegionBase<Tr>::element_iterator RegionBase<Tr>::element_begin() {
294  return GraphTraits<RegionT *>::nodes_begin(static_cast<RegionT *>(this));
295}
296
297template <class Tr>
298typename RegionBase<Tr>::element_iterator RegionBase<Tr>::element_end() {
299  return GraphTraits<RegionT *>::nodes_end(static_cast<RegionT *>(this));
300}
301
302template <class Tr>
303typename RegionBase<Tr>::const_element_iterator
304RegionBase<Tr>::element_begin() const {
305  return GraphTraits<const RegionT *>::nodes_begin(
306      static_cast<const RegionT *>(this));
307}
308
309template <class Tr>
310typename RegionBase<Tr>::const_element_iterator
311RegionBase<Tr>::element_end() const {
312  return GraphTraits<const RegionT *>::nodes_end(
313      static_cast<const RegionT *>(this));
314}
315
316template <class Tr>
317typename Tr::RegionT *RegionBase<Tr>::getSubRegionNode(BlockT *BB) const {
318  using RegionT = typename Tr::RegionT;
319
320  RegionT *R = RI->getRegionFor(BB);
321
322  if (!R || R == this)
323    return nullptr;
324
325  // If we pass the BB out of this region, that means our code is broken.
326  assert(contains(R) && "BB not in current region!");
327
328  while (contains(R->getParent()) && R->getParent() != this)
329    R = R->getParent();
330
331  if (R->getEntry() != BB)
332    return nullptr;
333
334  return R;
335}
336
337template <class Tr>
338typename Tr::RegionNodeT *RegionBase<Tr>::getBBNode(BlockT *BB) const {
339  assert(contains(BB) && "Can get BB node out of this region!");
340
341  typename BBNodeMapT::const_iterator at = BBNodeMap.find(BB);
342
343  if (at == BBNodeMap.end()) {
344    auto Deconst = const_cast<RegionBase<Tr> *>(this);
345    typename BBNodeMapT::value_type V = {
346        BB,
347        std::make_unique<RegionNodeT>(static_cast<RegionT *>(Deconst), BB)};
348    at = BBNodeMap.insert(std::move(V)).first;
349  }
350  return at->second.get();
351}
352
353template <class Tr>
354typename Tr::RegionNodeT *RegionBase<Tr>::getNode(BlockT *BB) const {
355  assert(contains(BB) && "Can get BB node out of this region!");
356  if (RegionT *Child = getSubRegionNode(BB))
357    return Child->getNode();
358
359  return getBBNode(BB);
360}
361
362template <class Tr>
363void RegionBase<Tr>::transferChildrenTo(RegionT *To) {
364  for (std::unique_ptr<RegionT> &R : *this) {
365    R->parent = To;
366    To->children.push_back(std::move(R));
367  }
368  children.clear();
369}
370
371template <class Tr>
372void RegionBase<Tr>::addSubRegion(RegionT *SubRegion, bool moveChildren) {
373  assert(!SubRegion->parent && "SubRegion already has a parent!");
374  assert(llvm::none_of(*this,
375                       [&](const std::unique_ptr<RegionT> &R) {
376                         return R.get() == SubRegion;
377                       }) &&
378         "Subregion already exists!");
379
380  SubRegion->parent = static_cast<RegionT *>(this);
381  children.push_back(std::unique_ptr<RegionT>(SubRegion));
382
383  if (!moveChildren)
384    return;
385
386  assert(SubRegion->children.empty() &&
387         "SubRegions that contain children are not supported");
388
389  for (RegionNodeT *Element : elements()) {
390    if (!Element->isSubRegion()) {
391      BlockT *BB = Element->template getNodeAs<BlockT>();
392
393      if (SubRegion->contains(BB))
394        RI->setRegionFor(BB, SubRegion);
395    }
396  }
397
398  std::vector<std::unique_ptr<RegionT>> Keep;
399  for (std::unique_ptr<RegionT> &R : *this) {
400    if (SubRegion->contains(R.get()) && R.get() != SubRegion) {
401      R->parent = SubRegion;
402      SubRegion->children.push_back(std::move(R));
403    } else
404      Keep.push_back(std::move(R));
405  }
406
407  children.clear();
408  children.insert(
409      children.begin(),
410      std::move_iterator<typename RegionSet::iterator>(Keep.begin()),
411      std::move_iterator<typename RegionSet::iterator>(Keep.end()));
412}
413
414template <class Tr>
415typename Tr::RegionT *RegionBase<Tr>::removeSubRegion(RegionT *Child) {
416  assert(Child->parent == this && "Child is not a child of this region!");
417  Child->parent = nullptr;
418  typename RegionSet::iterator I =
419      llvm::find_if(children, [&](const std::unique_ptr<RegionT> &R) {
420        return R.get() == Child;
421      });
422  assert(I != children.end() && "Region does not exit. Unable to remove.");
423  children.erase(children.begin() + (I - begin()));
424  return Child;
425}
426
427template <class Tr>
428unsigned RegionBase<Tr>::getDepth() const {
429  unsigned Depth = 0;
430
431  for (RegionT *R = getParent(); R != nullptr; R = R->getParent())
432    ++Depth;
433
434  return Depth;
435}
436
437template <class Tr>
438typename Tr::RegionT *RegionBase<Tr>::getExpandedRegion() const {
439  unsigned NumSuccessors = Tr::getNumSuccessors(exit);
440
441  if (NumSuccessors == 0)
442    return nullptr;
443
444  RegionT *R = RI->getRegionFor(exit);
445
446  if (R->getEntry() != exit) {
447    for (BlockT *Pred : llvm::inverse_children<BlockT *>(getExit()))
448      if (!contains(Pred))
449        return nullptr;
450    if (Tr::getNumSuccessors(exit) == 1)
451      return new RegionT(getEntry(), *BlockTraits::child_begin(exit), RI, DT);
452    return nullptr;
453  }
454
455  while (R->getParent() && R->getParent()->getEntry() == exit)
456    R = R->getParent();
457
458  for (BlockT *Pred : llvm::inverse_children<BlockT *>(getExit())) {
459    if (!(contains(Pred) || R->contains(Pred)))
460      return nullptr;
461  }
462
463  return new RegionT(getEntry(), R->getExit(), RI, DT);
464}
465
466template <class Tr>
467void RegionBase<Tr>::print(raw_ostream &OS, bool print_tree, unsigned level,
468                           PrintStyle Style) const {
469  if (print_tree)
470    OS.indent(level * 2) << '[' << level << "] " << getNameStr();
471  else
472    OS.indent(level * 2) << getNameStr();
473
474  OS << '\n';
475
476  if (Style != PrintNone) {
477    OS.indent(level * 2) << "{\n";
478    OS.indent(level * 2 + 2);
479
480    if (Style == PrintBB) {
481      for (const auto *BB : blocks())
482        OS << BB->getName() << ", "; // TODO: remove the last ","
483    } else if (Style == PrintRN) {
484      for (const RegionNodeT *Element : elements()) {
485        OS << *Element << ", "; // TODO: remove the last ",
486      }
487    }
488
489    OS << '\n';
490  }
491
492  if (print_tree) {
493    for (const std::unique_ptr<RegionT> &R : *this)
494      R->print(OS, print_tree, level + 1, Style);
495  }
496
497  if (Style != PrintNone)
498    OS.indent(level * 2) << "} \n";
499}
500
501#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
502template <class Tr>
503void RegionBase<Tr>::dump() const {
504  print(dbgs(), true, getDepth(), RegionInfoBase<Tr>::printStyle);
505}
506#endif
507
508template <class Tr>
509void RegionBase<Tr>::clearNodeCache() {
510  BBNodeMap.clear();
511  for (std::unique_ptr<RegionT> &R : *this)
512    R->clearNodeCache();
513}
514
515//===----------------------------------------------------------------------===//
516// RegionInfoBase implementation
517//
518
519template <class Tr>
520RegionInfoBase<Tr>::RegionInfoBase() = default;
521
522template <class Tr>
523RegionInfoBase<Tr>::~RegionInfoBase() {
524  releaseMemory();
525}
526
527template <class Tr>
528void RegionInfoBase<Tr>::verifyBBMap(const RegionT *R) const {
529  assert(R && "Re must be non-null");
530  for (const typename Tr::RegionNodeT *Element : R->elements()) {
531    if (Element->isSubRegion()) {
532      const RegionT *SR = Element->template getNodeAs<RegionT>();
533      verifyBBMap(SR);
534    } else {
535      BlockT *BB = Element->template getNodeAs<BlockT>();
536      if (getRegionFor(BB) != R)
537        report_fatal_error("BB map does not match region nesting");
538    }
539  }
540}
541
542template <class Tr>
543bool RegionInfoBase<Tr>::isCommonDomFrontier(BlockT *BB, BlockT *entry,
544                                             BlockT *exit) const {
545  for (BlockT *P : llvm::inverse_children<BlockT *>(BB)) {
546    if (DT->dominates(entry, P) && !DT->dominates(exit, P))
547      return false;
548  }
549
550  return true;
551}
552
553template <class Tr>
554bool RegionInfoBase<Tr>::isRegion(BlockT *entry, BlockT *exit) const {
555  assert(entry && exit && "entry and exit must not be null!");
556
557  using DST = typename DomFrontierT::DomSetType;
558
559  DST *entrySuccs = &DF->find(entry)->second;
560
561  // Exit is the header of a loop that contains the entry. In this case,
562  // the dominance frontier must only contain the exit.
563  if (!DT->dominates(entry, exit)) {
564    for (BlockT *successor : *entrySuccs) {
565      if (successor != exit && successor != entry)
566        return false;
567    }
568
569    return true;
570  }
571
572  DST *exitSuccs = &DF->find(exit)->second;
573
574  // Do not allow edges leaving the region.
575  for (BlockT *Succ : *entrySuccs) {
576    if (Succ == exit || Succ == entry)
577      continue;
578    if (!exitSuccs->contains(Succ))
579      return false;
580    if (!isCommonDomFrontier(Succ, entry, exit))
581      return false;
582  }
583
584  // Do not allow edges pointing into the region.
585  for (BlockT *Succ : *exitSuccs) {
586    if (DT->properlyDominates(entry, Succ) && Succ != exit)
587      return false;
588  }
589
590  return true;
591}
592
593template <class Tr>
594void RegionInfoBase<Tr>::insertShortCut(BlockT *entry, BlockT *exit,
595                                        BBtoBBMap *ShortCut) const {
596  assert(entry && exit && "entry and exit must not be null!");
597
598  typename BBtoBBMap::iterator e = ShortCut->find(exit);
599
600  if (e == ShortCut->end())
601    // No further region at exit available.
602    (*ShortCut)[entry] = exit;
603  else {
604    // We found a region e that starts at exit. Therefore (entry, e->second)
605    // is also a region, that is larger than (entry, exit). Insert the
606    // larger one.
607    BlockT *BB = e->second;
608    (*ShortCut)[entry] = BB;
609  }
610}
611
612template <class Tr>
613typename Tr::DomTreeNodeT *
614RegionInfoBase<Tr>::getNextPostDom(DomTreeNodeT *N, BBtoBBMap *ShortCut) const {
615  typename BBtoBBMap::iterator e = ShortCut->find(N->getBlock());
616
617  if (e == ShortCut->end())
618    return N->getIDom();
619
620  return PDT->getNode(e->second)->getIDom();
621}
622
623template <class Tr>
624bool RegionInfoBase<Tr>::isTrivialRegion(BlockT *entry, BlockT *exit) const {
625  assert(entry && exit && "entry and exit must not be null!");
626
627  unsigned num_successors =
628      BlockTraits::child_end(entry) - BlockTraits::child_begin(entry);
629
630  if (num_successors <= 1 && exit == *(BlockTraits::child_begin(entry)))
631    return true;
632
633  return false;
634}
635
636template <class Tr>
637typename Tr::RegionT *RegionInfoBase<Tr>::createRegion(BlockT *entry,
638                                                       BlockT *exit) {
639  assert(entry && exit && "entry and exit must not be null!");
640
641  if (isTrivialRegion(entry, exit))
642    return nullptr;
643
644  RegionT *region =
645      new RegionT(entry, exit, static_cast<RegionInfoT *>(this), DT);
646  BBtoRegion.insert({entry, region});
647
648  region->verifyRegion();
649
650  updateStatistics(region);
651  return region;
652}
653
654template <class Tr>
655void RegionInfoBase<Tr>::findRegionsWithEntry(BlockT *entry,
656                                              BBtoBBMap *ShortCut) {
657  assert(entry);
658
659  DomTreeNodeT *N = PDT->getNode(entry);
660  if (!N)
661    return;
662
663  RegionT *lastRegion = nullptr;
664  BlockT *lastExit = entry;
665
666  // As only a BasicBlock that postdominates entry can finish a region, walk the
667  // post dominance tree upwards.
668  while ((N = getNextPostDom(N, ShortCut))) {
669    BlockT *exit = N->getBlock();
670
671    if (!exit)
672      break;
673
674    if (isRegion(entry, exit)) {
675      RegionT *newRegion = createRegion(entry, exit);
676
677      if (lastRegion)
678        newRegion->addSubRegion(lastRegion);
679
680      lastRegion = newRegion;
681      lastExit = exit;
682    }
683
684    // This can never be a region, so stop the search.
685    if (!DT->dominates(entry, exit))
686      break;
687  }
688
689  // Tried to create regions from entry to lastExit.  Next time take a
690  // shortcut from entry to lastExit.
691  if (lastExit != entry)
692    insertShortCut(entry, lastExit, ShortCut);
693}
694
695template <class Tr>
696void RegionInfoBase<Tr>::scanForRegions(FuncT &F, BBtoBBMap *ShortCut) {
697  using FuncPtrT = std::add_pointer_t<FuncT>;
698
699  BlockT *entry = GraphTraits<FuncPtrT>::getEntryNode(&F);
700  DomTreeNodeT *N = DT->getNode(entry);
701
702  // Iterate over the dominance tree in post order to start with the small
703  // regions from the bottom of the dominance tree.  If the small regions are
704  // detected first, detection of bigger regions is faster, as we can jump
705  // over the small regions.
706  for (auto DomNode : post_order(N))
707    findRegionsWithEntry(DomNode->getBlock(), ShortCut);
708}
709
710template <class Tr>
711typename Tr::RegionT *RegionInfoBase<Tr>::getTopMostParent(RegionT *region) {
712  while (region->getParent())
713    region = region->getParent();
714
715  return region;
716}
717
718template <class Tr>
719void RegionInfoBase<Tr>::buildRegionsTree(DomTreeNodeT *N, RegionT *region) {
720  BlockT *BB = N->getBlock();
721
722  // Passed region exit
723  while (BB == region->getExit())
724    region = region->getParent();
725
726  typename BBtoRegionMap::iterator it = BBtoRegion.find(BB);
727
728  // This basic block is a start block of a region. It is already in the
729  // BBtoRegion relation. Only the child basic blocks have to be updated.
730  if (it != BBtoRegion.end()) {
731    RegionT *newRegion = it->second;
732    region->addSubRegion(getTopMostParent(newRegion));
733    region = newRegion;
734  } else {
735    BBtoRegion[BB] = region;
736  }
737
738  for (DomTreeNodeBase<BlockT> *C : *N) {
739    buildRegionsTree(C, region);
740  }
741}
742
743#ifdef EXPENSIVE_CHECKS
744template <class Tr>
745bool RegionInfoBase<Tr>::VerifyRegionInfo = true;
746#else
747template <class Tr>
748bool RegionInfoBase<Tr>::VerifyRegionInfo = false;
749#endif
750
751template <class Tr>
752typename Tr::RegionT::PrintStyle RegionInfoBase<Tr>::printStyle =
753    RegionBase<Tr>::PrintNone;
754
755template <class Tr>
756void RegionInfoBase<Tr>::print(raw_ostream &OS) const {
757  OS << "Region tree:\n";
758  TopLevelRegion->print(OS, true, 0, printStyle);
759  OS << "End region tree\n";
760}
761
762#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
763template <class Tr>
764void RegionInfoBase<Tr>::dump() const { print(dbgs()); }
765#endif
766
767template <class Tr> void RegionInfoBase<Tr>::releaseMemory() {
768  BBtoRegion.clear();
769  if (TopLevelRegion) {
770    delete TopLevelRegion;
771    TopLevelRegion = nullptr;
772  }
773}
774
775template <class Tr>
776void RegionInfoBase<Tr>::verifyAnalysis() const {
777  // Do only verify regions if explicitely activated using EXPENSIVE_CHECKS or
778  // -verify-region-info
779  if (!RegionInfoBase<Tr>::VerifyRegionInfo)
780    return;
781
782  TopLevelRegion->verifyRegionNest();
783
784  verifyBBMap(TopLevelRegion);
785}
786
787// Region pass manager support.
788template <class Tr>
789typename Tr::RegionT *RegionInfoBase<Tr>::getRegionFor(BlockT *BB) const {
790  return BBtoRegion.lookup(BB);
791}
792
793template <class Tr>
794void RegionInfoBase<Tr>::setRegionFor(BlockT *BB, RegionT *R) {
795  BBtoRegion[BB] = R;
796}
797
798template <class Tr>
799typename Tr::RegionT *RegionInfoBase<Tr>::operator[](BlockT *BB) const {
800  return getRegionFor(BB);
801}
802
803template <class Tr>
804typename RegionInfoBase<Tr>::BlockT *
805RegionInfoBase<Tr>::getMaxRegionExit(BlockT *BB) const {
806  BlockT *Exit = nullptr;
807
808  while (true) {
809    // Get largest region that starts at BB.
810    RegionT *R = getRegionFor(BB);
811    while (R && R->getParent() && R->getParent()->getEntry() == BB)
812      R = R->getParent();
813
814    // Get the single exit of BB.
815    if (R && R->getEntry() == BB)
816      Exit = R->getExit();
817    else if (++BlockTraits::child_begin(BB) == BlockTraits::child_end(BB))
818      Exit = *BlockTraits::child_begin(BB);
819    else // No single exit exists.
820      return Exit;
821
822    // Get largest region that starts at Exit.
823    RegionT *ExitR = getRegionFor(Exit);
824    while (ExitR && ExitR->getParent() &&
825           ExitR->getParent()->getEntry() == Exit)
826      ExitR = ExitR->getParent();
827
828    for (BlockT *Pred : llvm::inverse_children<BlockT *>(Exit)) {
829      if (!R->contains(Pred) && !ExitR->contains(Pred))
830        break;
831    }
832
833    // This stops infinite cycles.
834    if (DT->dominates(Exit, BB))
835      break;
836
837    BB = Exit;
838  }
839
840  return Exit;
841}
842
843template <class Tr>
844typename Tr::RegionT *RegionInfoBase<Tr>::getCommonRegion(RegionT *A,
845                                                          RegionT *B) const {
846  assert(A && B && "One of the Regions is NULL");
847
848  if (A->contains(B))
849    return A;
850
851  while (!B->contains(A))
852    B = B->getParent();
853
854  return B;
855}
856
857template <class Tr>
858typename Tr::RegionT *
859RegionInfoBase<Tr>::getCommonRegion(SmallVectorImpl<RegionT *> &Regions) const {
860  RegionT *ret = Regions.pop_back_val();
861
862  for (RegionT *R : Regions)
863    ret = getCommonRegion(ret, R);
864
865  return ret;
866}
867
868template <class Tr>
869typename Tr::RegionT *
870RegionInfoBase<Tr>::getCommonRegion(SmallVectorImpl<BlockT *> &BBs) const {
871  RegionT *ret = getRegionFor(BBs.back());
872  BBs.pop_back();
873
874  for (BlockT *BB : BBs)
875    ret = getCommonRegion(ret, getRegionFor(BB));
876
877  return ret;
878}
879
880template <class Tr>
881void RegionInfoBase<Tr>::calculate(FuncT &F) {
882  using FuncPtrT = std::add_pointer_t<FuncT>;
883
884  // ShortCut a function where for every BB the exit of the largest region
885  // starting with BB is stored. These regions can be threated as single BBS.
886  // This improves performance on linear CFGs.
887  BBtoBBMap ShortCut;
888
889  scanForRegions(F, &ShortCut);
890  BlockT *BB = GraphTraits<FuncPtrT>::getEntryNode(&F);
891  buildRegionsTree(DT->getNode(BB), TopLevelRegion);
892}
893
894} // end namespace llvm
895
896#undef DEBUG_TYPE
897
898#endif // LLVM_ANALYSIS_REGIONINFOIMPL_H
899